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Sample records for intraatomic ru interactions

  1. Mechanisms of anomalous interaction between the intraatomic excitations and conduction electrons in rare-earth intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Kikoin, K.A. (AN SSSR, Moscow USSR. Kurchatov Inst. (USSR)); Khomskii, D.I. (AN SSSR, Moscow USSR. Lebedev Physical Inst. (USSR))

    1988-12-01

    Essentially atomic electron-polaron mechanism reducing the magnetic moments of rare-earth and actinide elements in intermetallic compounds is proposed. This mechanism is effective for the atoms possessing soft intraatomic excitations in f- and d-channels (Ce,U,Eu,Yb).

  2. Atomic hydrogen interaction with Ru(1010).

    Science.gov (United States)

    Vesselli, E; Comelli, G; Rosei, R

    2004-05-01

    The interaction of atomic hydrogen with clean and deuterium precovered Ru(1010) was studied by means of temperature-programmed desorption (TPD) spectroscopy. Compared to molecular hydrogen experiments, after exposure of the clean surface to gas-phase atomic hydrogen at 90 K, two additional peaks grow in the desorption spectra at 115 and 150 K. The surface saturation coverage, determined by equilibrium between abstraction and adsorption reactions, is 2.5 monolayers. Preadsorbed deuterium abstraction experiments with gas-phase atomic hydrogen show that a pure Eley-Rideal mechanism is not involved in the process, while a hot atom (HA) kinetics describes well the reaction. By least-squares fitting of the experimental data, a simplified HA kinetic model yields an abstraction cross section value of 0.5 +/- 0.2 angstroms2. The atomic hydrogen interaction with an oxygen precovered surface was also studied by means of both TPD and x-ray photoelectron spectroscopy: oxygen hydrogenation and water production take place already at very low temperature (90 K).

  3. Potassium-oxygen interactions on a Ru(001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Hrbek, J.; Shek, M.L.; Xu, G.Q. (Brookhaven National Lab., Upton, NY (United States)); Sham, T.K. (Univ. of Western Ontario, London, Ontario (Canada))

    1992-10-01

    The interaction of potassium with oxygen has been examined using synchrotron-based photoemission and NEXAFS, thermal desorption, work function measurements, and isotope exchange. Potassium coverages on Ru(001) surface ranging from monolayer to multilayer were investigated. Oxygen coadsorbed with potassium at 80 K forms a potassium-dioxygen complex, where both peroxide and superoxide ions were identified. The complex has high thermal stability on the Ru(001) surface, decomposing and desorbing at T > 900 K. 52 refs., 14 figs., 2 tabs.

  4. A model system for carbohydrates interactions on single-crystalline Ru surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Thanh Nam

    2015-07-01

    In this thesis, I present a model system for carbohydrate interactions with single-crystalline Ru surfaces. Geometric and electronic properties of copper phthalocyanine (CuPc) on top of graphene on hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10) surfaces have been studied. First, the Fermi surfaces and band structures of the three Ru surfaces were investigated by high-resolution angle-resolved photoemission spectroscopy. The experimental data and theoretical calculations allow to derive detailed information about the momentum-resolved electronic structure. The results can be used as a reference to understand the chemical and catalytic properties of Ru surfaces. Second, graphene layers were prepared on the three different Ru surfaces. Using low-energy electron diffraction and scanning tunneling microscopy, it was found that graphene can be grown in well-ordered structures on all three surfaces, hexagonal Ru(0001), rectangular Ru(10 anti 10) and vicinal Ru(1,1, anti 2,10), although they have different surface symmetries. Evidence for a strong interaction between graphene and Ru surfaces is a 1.3-1.7 eV increase in the graphene π-bands binding energy with respect to free-standing graphene sheets. This energy variation is due to the hybridization between the graphene pi bands and the Ru 4d electrons, while the lattice mismatch does not play an important role in the bonding between graphene and Ru surfaces. Finally, the geometric and electronic structures of CuPc on Ru(10 anti 10), graphene/Ru(10 anti 10), and graphene/Ru(0001) have been studied in detail. CuPc molecules can be grown well-ordered on Ru(10 anti 10) but not on Ru(0001). The growth of CuPc on graphene/Ru(10 anti 10) and Ru(0001) is dominated by the Moire pattern of graphene. CuPc molecules form well-ordered structures with rectangular unit cells on graphene/Ru(10 anti 10) and Ru(0001). The distance of adjacent CuPc molecules is 15±0.5 Aa and 13±0.5 Aa on graphene/Ru(0001

  5. Investigation of Even-Even Ru Isotopes in Interacting Boson Model-2

    Institute of Scientific and Technical Information of China (English)

    A.H. Yilmaz; M. Kuruoglu

    2006-01-01

    The interacting boson model of Arima, Iachello, and co-workers is applied to the even ruthenium isotopes,96 Ru ~ 116Ru. Excitation energies, electromagnetic transition strengths, quadrupole and magnetic dipole moments, and △(E2/M1) mixing ratios have been described systematically. Mixed symmetry states are investigated. It is seen that the properties of low-lying levels in these isotopes, for which the comparison between experiment and theory is possible,can be satisfactorily characterized by the Interacting Boson Model-2.

  6. Increasing the bioavailability of Ru(III) anticancer complexes through hydrophobic albumin interactions.

    Science.gov (United States)

    Webb, Michael I; Wu, Boris; Jang, Thalia; Chard, Ryan A; Wong, Edwin W Y; Wong, May Q; Yapp, Donald T T; Walsby, Charles J

    2013-12-09

    A series of pyridine-based derivatives of the clinically successful Ru(III)-based complexes indazolium [trans-RuCl4(1H-indazole)2] (KP1019) and sodium [trans-RuCl4(1H-indazole)2] (KP1339) have been synthesized to probe the effect of hydrophobic interactions with human serum albumin (hsA) on anticancer activity. The solution behavior and protein interactions of the new compounds were characterized by using electron paramagnetic resonance (EPR) and UV/Vis spectroscopy. These studies have revealed that incorporation of hydrophobic substituents at the 4'-position of the axial pyridine ligand stabilizes non-coordinate interactions with hsA. As a consequence, direct coordination to the protein is inhibited, which is expected to increase the bioavailability of the complexes, thus potentially leading to improved anticancer activity. By using this approach, the lifetimes of hydrophobic protein interactions were extended from 2 h for the unsubstituted pyridine complex, to more than 24 h for several derivatives. Free complexes were tested for their anticancer activity against the SW480 human colon carcinoma cell line, exhibiting low cytotoxicity. Pre-treatment with hsA improved the solubility of every compound and led to some changes in activity. Particularly notable was the difference in activity between the methyl- and dibenzyl-functionalized complexes. The former shows reduced activity after incubation with hsA, indicating reduced bioavailability due to protein coordination. The latter exhibits little activity on its own but, following treatment with hsA, exhibited significant cytotoxicity, which is consistent with its ability to form non-coordinate interactions with the protein. Overall, our studies demonstrate that non-coordinate interactions with hsA are a viable target for enhancing the activity of Ru(III)-based complexes in vivo.

  7. Evolution of magnetic properties and exchange interactions in Ru doped YbCrO3

    Science.gov (United States)

    Dalal, Biswajit; Sarkar, Babusona; Ashok, Vishal Dev; De, S. K.

    2016-10-01

    Magnetic properties of YbCr1-x Ru x O3 as a function of temperature and magnetic field have been investigated to explore the intriguing magnetic phenomena in rare-earth orthochromites. A quantitative analysis of x-ray photoelectron spectroscopy confirms the mixed valence state (Yb3+ and Yb2+) of Yb ions for the highest doped sample. Field-cooled magnetization reveals a broad peak around 75 K and then becomes zero at about 20-24 K, due to the antiparallel coupling between Cr3+ and Yb3+ moments. An increase of the Ru4+ ion concentration leads to a slight increase of compensation temperature T comp from 20 to 24 K, but the Néel temperature remains constant. A larger value of the magnetic moment of Yb ions gives rise to negative magnetization at low temperature. An external magnetic field significantly modifies the temperature dependent magnetization. Simulation of temperature dependent magnetization data, below T N, based on the three (two) magnetic sub-lattice model predicts stronger intra-sublattice exchange interaction than that of inter-sublattice. Thermal hysteresis and Arrot plots suggest first order magnetic phase transition. Random substitution of Ru4+ ion reduces the magnetic relaxation time. Weak ferromagnetic component in canted antiferromagnetic system and negative internal magnetic field cause zero-field-cooled exchange bias effect. Large magnetocrystalline anisotropy associated with Ru creates high coercivity in the Ru doped sample. A maximum value of magnetocaloric effect is found around the antiferromagnetic ordering of Yb3+ ions. Antiferromagnetic transition at about 120 K and temperature induced magnetization reversal lead to normal and inverse magnetocaloric effects in the same material.

  8. EXAFS Peaks and TPR Characterizing Bimetallic Interactions: Effects of Impregnation Methods on the Structure of Pt-Ru/C Catalysts

    Directory of Open Access Journals (Sweden)

    Nan-Yu Chen

    2014-01-01

    Full Text Available To investigate bimetallic interactions, Pt-Ru/C catalysts were prepared by coimpregnation (Pt-Ruco/C and successive impregnation (Ru-Ptse/C, while Pt/C, Ru/C, and reduced Pt-Rublack were used as reference. Those samples were characterized by XAS and TPR. When Pt(absorber-Ru(backscatter phase-and-amplitude correction is applied to Fourier transformed (FT EXAFS of Pt-Rublack at Pt edge, the characteristic peak of Pt-Ru interactions appears at 2.70 Å´, whereas, when Pt-Pt correction is applied, the peak appears at about 2.5 Å´. Detailed EXAFS analysis for Pt-Ruco/C and Pt-Ruse/C confirms the nature of the characteristic peak and further indicates that the interactions can semiquantitatively be determined by the relative intensity between Pt-Ru and Pt-Pt characteristic peaks. This simple method in determining bimetallic interaction can be extended to characterize Pt-Pd/γ-Al2O3. However, for Pt-Re/γ-Al2O3, Pt-Re interactions cannot be determined by the method because of the overlap of Pt-Pt and Pt-Re characteristic peaks due to similar phase functions.

  9. First-principle investigation of the interactions between PtxRu55-x (x = 0, 13, 42, 55) nanoparticles and [BMIM][PF6] ionic liquid

    Science.gov (United States)

    Cheng, Ping; Liu, Chuan; Yang, Yongpeng; Huang, Shiping

    2015-05-01

    Density functional theory calculations have been performed to characterize the interactions between [BMIM][PF6] ionic liquid and icosahedral PtxRu55-x (x = 0, 13, 42, 55) nanoparticles. In Ru13Pt42-[BMIM][PF6], only one F atom of the anion form the bond with nanoparticle, resulting in the smallest interaction energy (-0.56 eV). While in Pt13Ru42-[BMIM][PF6], two F atoms of the anion together with two C atoms of cation form the bonds with nanoparticle, resulting in the biggest interaction energy (-10.65 eV). The interaction between [BMIM][PF6] and Pt13Ru42 is so strong that it induces a significant distortion in the original core-shell structure of Pt13Ru42. Moreover, after interacting with [BMIM][PF6], the Pt55, Pt13Ru42 and Ru55 nanoparticles become more stable based on the negative relaxation energy. The d-band centers of Pt13Ru42 and Ru55 shift from -1.90, -1.78 eV up to -1.78, -1.56 eV, suggesting that the catalytic activities of Pt13Ru42 and Ru55 are enhanced.

  10. A theoretical study of adsorbate-adsorbate interactions on Ru(0001)

    DEFF Research Database (Denmark)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Using density functional theory we study the effect of pre-adsorbed atoms on the dissociation of N(2) and the adsorption of N, N(2), and CO on Ru(0001). We have done calculations for pre-adsorbed Na, Cs, and S, and find that alkali atoms adsorbed close to a dissociating N(2) molecule will lower...... the barrier for dissociation, whereas S will increase it. The interaction with alkali atoms is mainly of an electrostatic nature. The poisoning by S is due to two kinds of repulsive interactions: a Pauli repulsion and a reduced covalent bond strength between the adsorbate and the surface d-electrons. In order...... to investigate these different interactions in more detail, we look at three different species (N atoms, and terminally bonded N(2) and CO) and use them as probes to study their interaction with two modifier atoms (Na and S). The two modifier atoms have very different properties, which allows us to decouple...

  11. Thermodynamic investigations of [(phen)2Ru(tatpp)Ru(phen)2](4+) interactions with B-DNA.

    Science.gov (United States)

    Le, Vu H; McGuire, Matthew R; Ahuja, Pooja; MacDonnell, Frederick M; Lewis, Edwin A

    2015-01-08

    While the antitumor activity of P(4+) is relatively well understood, the binding mechanism and thermodynamics for formation of (P(4+)·DNA) complexes remain in question. The thermodynamic parameters (Ka, ΔG, ΔH, and -TΔS) for formation of DNA complexes of the ruthenium dimer, [(phen)2Ru(tatpp)Ru(phen)2](4+) (abbreviated as P(4+)), where phen is 1,10-phenanthroline and tatpp is 9,11,20,22-tetraazatetrapyrido[3,2-a:2',3'-c:3″,2″-1:2‴,3‴-n]-pentacene, were determined using isothermal titration calorimetry. Calorimetric and spectroscopic titration experiments were performed in which P(4+) was added to three duplex DNAs of different lengths. We determined that P(4+) binds to duplex DNA at 298 K with modest affinity (Ka ≈ 3.8 × 10(5) M(-1), ΔG ≈ -7.6 kcal/mol), that the enthalpy change is unfavorable (ΔH ≈ +2.1 kcal/mol), and that complex formation is driven by a large favorable change in entropy (-TΔS ≈ -9.7 kcal/mol). These thermodynamic values were found to be approximately independent of the length of the DNA, and the stoichiometry of the (P(4+)·DNA) complexes was determined to be 1 P(4+)/2 DNA bp, at least for the two shorter DNAs. On the basis of the thermodynamic parameters, and the binding stoichiometry (verified in ESI-MS experiments), we conclude that P(4+) is intercalating between two adjacent DNA base pairs and that the neighbor sites on either side of the bound ligand are excluded from binding additional P(4+).

  12. Ru(bipy)2(dppz)2+与DNA相互作用的光谱研究%Spectral Studies on the Interaction of DNA and Ru(bipy)2(dppz)2+

    Institute of Scientific and Technical Information of China (English)

    凌连生; 杨洗; 何治柯; 曾云鹗

    2001-01-01

    The interaction between Ru(bipy)2(dppz)2+(bipy=2,2-bipyridine,dppz=dipyrido[3,2-a:2′,3′-c]phenazine) and the calfthymus DNA was studied with fluorescence and ultraviolet visible absorption spectroscopy. The ultraviolet visible absorption spectra of Ru(bipy)2(dppz)2+, calfthymus DNA, and their interaction indicated that Ru(bipy)2(dppz)2+ intercalated into the double helix of DNA via the ligand dppz. The results of fluorescence quenching and salt effect also supported the intercalated binding mode.%利用荧光和紫外可见吸收光谱研究了Ru(bipy)2(dppz)2+与DNA之间的插入键合作用。结果表明,Ru(bipy)2(dppz)2+是通过dppz配体插入到DNA的双螺旋结构中。而且,一定浓度的Fe(CN)4-6和NaCl对Ru(bipy)2(dppz)2+-DNA复合物的荧光无猝灭作用,这一结果也证实了Ru(bipy)2(dppz)2+和DNA之间的插入键合作用。

  13. Interband coulomb interaction and horizontal line nodes in triplet superconductor Sr sub 2 RuO sub 4

    CERN Document Server

    Hasegawa, Y

    2003-01-01

    A possible mechanism for appearance of the horizontal line nodes in triplet superconductor, Sr sub 2 RuO sub 4 , is proposed. We consider the interlayer Coulomb interaction, as well as the on-site Coulomb repulsion, between electrons in different bands. In the second order perturbation of the interband interaction, the effective interaction becomes dependent on cos q sub z /2, resulting in horizontal line nodes. (author)

  14. Selective CO Methanation on Ru/TiO2 Catalysts: Role and Influence of Metal-Support Interactions

    DEFF Research Database (Denmark)

    Abdel-Mageed, Ali M.; Widmann, D.; Olesen, Sine Ellemann

    2015-01-01

    Aiming at a detailed understanding of the role of metal-support interactions in the selective methanation of CO in CO2-rich reformate gases, we have investigated the catalytic performance of a set of Ru/TiO2 catalysts with comparable Ru loading, Ru particle size, and TiO2 phase composition but very...... different surface areas (ranging from 20 to 235 m2 g-1) in this reaction. The activity for CO methanation, under steady-state conditions, was found to strongly depend on the TiO2 support surface area, increasing first with increasing surface area up to a maximum activity for the Ru/TiO2 catalyst...... with a surface area of 121 m2 g-1 and then decreasing for an even higher surface area; however, the selectivity is mainly determined by the Ru particle size, which slightly decreases with increasing support surface area. This goes along with an increase in selectivity for CO methanation, in agreement...

  15. Interaction between active ruthenium complex [RuCl3(dppb)(VPy)] and phospholipid Langmuir monolayers: Effects on membrane electrical properties

    Science.gov (United States)

    Sandrino, B.; Wrobel, E. C.; Nobre, T. M.; Caseli, L.; Lazaro, S. R.; Júnior, A. C.; Garcia, J. R.; Oliveira, O. N.; Wohnrath, K.

    2016-04-01

    We report on the interaction between mer-[RuCl3(dppb)(VPy)] (dppb = 1,4-bis(diphenylphosphine)butane and VPy = 4-vinylpyridine) (RuVPy) and dipalmitoyl phosphatidyl serine (DPPS), in Langmuir and Langmuir-Blodgett (LB) films. Interaction of RuVPy with DPPS, which predominates in cancer cell membranes, should be weaker than for other phospholipids since RuVPy is less toxic to cancer cells than to healthy cells. Incorporation of RuVPy induced smaller changes in electrochemical properties of LB films of DPPS than for other phospholipids, but the same did not apply to surface pressure isotherms. This calls for caution in establishing correlations between effects from a single property and phenomena on cell membranes.

  16. U(5) symmetry of even {sup 96,98}Ru isotopes under the framework of interacting Boson model (IBM-1)

    Energy Technology Data Exchange (ETDEWEB)

    Sharrad, Fadhil I.; Ahmed, A.S. [Department of Physics, College of Science, Kerbala University, Karbala (Iraq); Hossain, I., E-mail: mihossain@kau.edu.sa [Department of Physics, Rabigh College of Science and Arts, King Abdulaziz University, Rabigh (Saudi Arabia); Ahmed, I.M. [Department of Physics, College of Education, Mosul University, Mosul (Iraq); Abdullah, Hewa Y. [Department of Physics, College of Science Education, Salahaddin University, Erbil, KRG (Iraq); Ahmad, S.T. [Department of Physics, Faculty of Science, Koya University, Koya, KRG (Iraq)

    2015-06-15

    In this paper, the yrast bands of the even {sup 96,98}Ru isotopes are studied within the framework of the interacting boson model-1 (IBM-1), using the MATLAB computer code (IBM-1.Mat). The theoretical energy levels are obtained for the {sup 96,98}Ru isotopes, with neutron numbers 52 and 54, up to spin-parity 16{sup +} and 12{sup +}, respectively. The ratio of the excitation energies of the first 4{sup +} to the first 2{sup +} excited states (R{sub 4/2}), the backbending curves and the potential energy surfaces are also calculated. The calculated and experimental R{sub 4/2} values show that the {sup 96,98}Ru nuclei have U(5) dynamic symmetry. The calculated energies of the yrast states are compared with experimental results and they are shown to be in good agreement with the data. The contour plots of the potential energy surfaces show two interesting nuclei having a slightly oblate but almost spherical vibrator-like character. (author)

  17. Cytotoxicity of Ru(II) piano-stool complexes with chloroquine and chelating ligands against breast and lung tumor cells: Interactions with DNA and BSA.

    Science.gov (United States)

    Colina-Vegas, Legna; Villarreal, Wilmer; Navarro, Maribel; de Oliveira, Clayton Rodrigues; Graminha, Angélica E; Maia, Pedro Ivo da S; Deflon, Victor M; Ferreira, Antonio G; Cominetti, Marcia Regina; Batista, Alzir A

    2015-12-01

    The synthesis and spectroscopic characterization of nine π-arene piano-stool ruthenium (II) complexes with aromatic dinitrogen chelating ligands or containing chloroquine (CQ), are described in this study: [Ru(η(6)-C10H14)(phen)Cl]PF6 (1), [Ru(η(6)-C10H14)(dphphen)Cl]PF6 (2), [Ru(η(6)-C10H14)(bipy)Cl]PF6 (3), [Ru(η(6)-C10H14)(dmebipy)Cl]PF6 (4) and [Ru(η(6)-C10H14)(bdutbipy)Cl]PF6 (5), [Ru(η(6)-C10H14)(phen)CQ](PF6)2 (6), [Ru(η(6)-C10H14)(dphphen)CQ](PF6)2 (7), [Ru(η(6)-C10H14)(bipy)CQ](PF6)2 (8), [Ru(η(6)-C10H14)(dmebipy)CQ](PF6)2 (9): [1,10-phenanthroline (phen), 4,7-diphenyl-1,10-phenanthroline (dphphen), 2,2'-bipyridine (bipy), 5,5'-dimethyl-2,2'-bipyridine (dmebipy), and 4,4'-di-t-butyl-2,2'-bipyridine (dbutbipy)]. The solid state structures of five ruthenium complexes (1-5) were determined by X-ray crystallography. Electrochemical experiments were performed by cyclic voltammetry to estimate the redox potential of the Ru(II)/Ru(III) couple in each case. Their interactions with DNA and BSA, and activity against four cell lines (L929, A549, MDA-MB-231 and MCF-7) were evaluated. Compounds 2, 6 through 9, interact with DNA which was comparable to the one observed for free chloroquine. The results of fluorescence titration revealed that these complexes strongly quenched the intrinsic fluorescence of BSA following a static quenching procedure. Binding constants (Kb) and the number of binding sites (n~1) were calculated using modified Stern-Volmer equations. The thermodynamic parameters ΔG at different temperatures were calculated and subsequently the values of ΔH and ΔS were also calculated, which revealed that hydrophobic and electrostatic interactions play a major role in the BSA-complex association. The MTT assay results indicated that complexes 2, 5 and 7 showed cytostatic effects at appreciably lower concentrations than those needed for cisplatin, chloroquine and doxorubicin.

  18. Intermolecular vs molecule–substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001

    Directory of Open Access Journals (Sweden)

    Michael Roos

    2011-07-01

    Full Text Available The competition between intermolecular interactions and long-range lateral variations in the substrate–adsorbate interaction was studied by scanning tunnelling microscopy (STM and force field based calculations, by comparing the phase formation of (sub- monolayers of the organic molecules (i 2-phenyl-4,6-bis(6-(pyridin-3-yl-4-(pyridin-3-ylpyridin-2-ylpyrimidine (3,3'-BTP and (ii 3,4,9,10-perylene tetracarboxylic-dianhydride (PTCDA on graphene/Ru(0001. For PTCDA adsorption, a 2D adlayer phase was formed, which extended over large areas, while for 3,3'-BTP adsorption linear or ring like structures were formed, which exclusively populated the areas between the maxima of the moiré structure of the buckled graphene layer. The consequences for the competing intermolecular interactions and corrugation in the adsorption potential are discussed and compared with the theoretical results.

  19. Intermolecular vs molecule-substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001).

    Science.gov (United States)

    Roos, Michael; Uhl, Benedikt; Künzel, Daniela; Hoster, Harry E; Groß, Axel; Behm, R Jürgen

    2011-01-01

    The competition between intermolecular interactions and long-range lateral variations in the substrate-adsorbate interaction was studied by scanning tunnelling microscopy (STM) and force field based calculations, by comparing the phase formation of (sub-) monolayers of the organic molecules (i) 2-phenyl-4,6-bis(6-(pyridin-3-yl)-4-(pyridin-3-yl)pyridin-2-yl)pyrimidine (3,3'-BTP) and (ii) 3,4,9,10-perylene tetracarboxylic-dianhydride (PTCDA) on graphene/Ru(0001). For PTCDA adsorption, a 2D adlayer phase was formed, which extended over large areas, while for 3,3'-BTP adsorption linear or ring like structures were formed, which exclusively populated the areas between the maxima of the moiré structure of the buckled graphene layer. The consequences for the competing intermolecular interactions and corrugation in the adsorption potential are discussed and compared with the theoretical results.

  20. Intermolecular vs molecule–substrate interactions: A combined STM and theoretical study of supramolecular phases on graphene/Ru(0001)

    Science.gov (United States)

    Roos, Michael; Uhl, Benedikt; Künzel, Daniela; Hoster, Harry E; Groß, Axel

    2011-01-01

    Summary The competition between intermolecular interactions and long-range lateral variations in the substrate–adsorbate interaction was studied by scanning tunnelling microscopy (STM) and force field based calculations, by comparing the phase formation of (sub-) monolayers of the organic molecules (i) 2-phenyl-4,6-bis(6-(pyridin-3-yl)-4-(pyridin-3-yl)pyridin-2-yl)pyrimidine (3,3'-BTP) and (ii) 3,4,9,10-perylene tetracarboxylic-dianhydride (PTCDA) on graphene/Ru(0001). For PTCDA adsorption, a 2D adlayer phase was formed, which extended over large areas, while for 3,3'-BTP adsorption linear or ring like structures were formed, which exclusively populated the areas between the maxima of the moiré structure of the buckled graphene layer. The consequences for the competing intermolecular interactions and corrugation in the adsorption potential are discussed and compared with the theoretical results. PMID:22003444

  1. Fermi Surface of Sr_{2}RuO_{4}: Spin-Orbit and Anisotropic Coulomb Interaction Effects.

    Science.gov (United States)

    Zhang, Guoren; Gorelov, Evgeny; Sarvestani, Esmaeel; Pavarini, Eva

    2016-03-11

    The topology of the Fermi surface of Sr_{2}RuO_{4} is well described by local-density approximation calculations with spin-orbit interaction, but the relative size of its different sheets is not. By accounting for many-body effects via dynamical mean-field theory, we show that the standard isotropic Coulomb interaction alone worsens or does not correct this discrepancy. In order to reproduce experiments, it is essential to account for the Coulomb anisotropy. The latter is small but has strong effects; it competes with the Coulomb-enhanced spin-orbit coupling and the isotropic Coulomb term in determining the Fermi surface shape. Its effects are likely sizable in other correlated multiorbital systems. In addition, we find that the low-energy self-energy matrix-responsible for the reshaping of the Fermi surface-sizably differs from the static Hartree-Fock limit. Finally, we find a strong spin-orbital entanglement; this supports the view that the conventional description of Cooper pairs via factorized spin and orbital part might not apply to Sr_{2}RuO_{4}.

  2. Strong influence of coadsorbate interaction on CO desorption dynamics on Ru(0001) probed by ultrafast x-ray spectroscopy and ab initio simulations

    Energy Technology Data Exchange (ETDEWEB)

    Xin, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); LaRue, J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Oberg, H. [Stockholm Univ., Stockholm (Sweden); Beye, M. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Dell' Angela, M. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Turner, J. J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Gladh, J. [Stockholm Univ., Stockholm (Sweden); Ng, M. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Sellberg, J. A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Kaya, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Mercurio, G. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Hieke, F. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); Nordlund, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Schlotter, W. F. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Dakovski, G. L. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Minitti, M. P. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Fohlisch, A. [Helmholtz Zentrum Berlin fur Materialien und Energie GmbH, Berlin (Germany); Univ. Potsdam, Potsdam (Germany); Wolf, M. [Fritz-Haber Institute of the Max-Planck-Society, Berlin (Germany); Wurth, W. [Univ. of Hamburg and Center for Free Electron Laser Science, Hamburg (Germany); DESY Photon Science, Hamburg (Germany); Ogasawara, H. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Norskov, J. K. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States); Ostrom, H. [Stockholm Univ., Stockholm (Sweden); Pettersson, L. G. M. [Stockholm Univ., Stockholm (Sweden); Nilsson, A. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stockholm Univ., Stockholm (Sweden); Ablid-Pedersen, F. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-04-16

    We show that coadsorbed oxygen atoms have a dramatic influence on the CO desorption dynamics from Ru(0001). In contrast to the precursor-mediated desorption mechanism on Ru(0001), the presence of surface oxygen modifies the electronic structure of Ru atoms such that CO desorption occurs predominantly via the direct pathway. This phenomenon is directly observed in an ultrafast pump-probe experiment using a soft x-ray free-electron laser to monitor the dynamic evolution of the valence electronic structure of the surface species. This is supported with the potential of mean force along the CO desorption path obtained from density-functional theory calculations. Charge density distribution and frozen-orbital analysis suggest that the oxygen-induced reduction of the Pauli repulsion, and consequent increase of the dative interaction between the CO 5σ and the charged Ru atom, is the electronic origin of the distinct desorption dynamics. Ab initio molecular dynamics simulations of CO desorption from Ru(0001) and oxygen-coadsorbed Ru(0001) provide further insights into the surface bond-breaking process.

  3. First-principle investigation of the interactions between Pt{sub x}Ru{sub 55−x} (x = 0, 13, 42, 55) nanoparticles and [BMIM][PF{sub 6}] ionic liquid

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Ping; Liu, Chuan; Yang, Yongpeng; Huang, Shiping, E-mail: huangsp@mail.buct.edu.cn

    2015-05-01

    Highlights: • Interaction between PtRu nanoparticle and [BMIM][PF{sub 6}] is performed by DFT calculations. • The structure of Pt{sub 13}Ru{sub 42} nanoparticle is distorted induced by [BMIM][PF{sub 6}]. • The d-band center show that catalytic activities of Pt{sub 13}Ru{sub 42} and Ru{sub 55} are enhanced. • Two C atoms of [BMIM][PF{sub 6}] form the bond with Pt{sub 13}Ru{sub 42} nanoparticles. - Abstract: Density functional theory calculations have been performed to characterize the interactions between [BMIM][PF{sub 6}] ionic liquid and icosahedral Pt{sub x}Ru{sub 55−x} (x = 0, 13, 42, 55) nanoparticles. In Ru{sub 13}Pt{sub 42}–[BMIM][PF{sub 6}], only one F atom of the anion form the bond with nanoparticle, resulting in the smallest interaction energy (−0.56 eV). While in Pt{sub 13}Ru{sub 42}–[BMIM][PF{sub 6}], two F atoms of the anion together with two C atoms of cation form the bonds with nanoparticle, resulting in the biggest interaction energy (−10.65 eV). The interaction between [BMIM][PF{sub 6}] and Pt{sub 13}Ru{sub 42} is so strong that it induces a significant distortion in the original core–shell structure of Pt{sub 13}Ru{sub 42}. Moreover, after interacting with [BMIM][PF{sub 6}], the Pt{sub 55}, Pt{sub 13}Ru{sub 42} and Ru{sub 55} nanoparticles become more stable based on the negative relaxation energy. The d-band centers of Pt{sub 13}Ru{sub 42} and Ru{sub 55} shift from −1.90, −1.78 eV up to −1.78, −1.56 eV, suggesting that the catalytic activities of Pt{sub 13}Ru{sub 42} and Ru{sub 55} are enhanced.

  4. Electrochemical behavior of Ru(H2bpp)2(PF6)2 and its interaction with bovine serum albumin (BSA)

    Institute of Scientific and Technical Information of China (English)

    Qiao Hua Wei; Li Jing Han; Jing Hua Chen; Fang Nan Xiao; Shen Liang Zeng; Guo Nan Chen

    2011-01-01

    In this paper, it was found that Ru(H2bpp)2(PF6)2 (H2bpp = 2,6-bis(pyrazol-3-yl)pyridine) complex had excellent electrochemical activity at the carbon paste electrode in the buffer solution of Tris-HCl (pH 7.0) with a couple reversible redox peaks at 0.296 V and 0.348 V, respectively. Voltammetry was used to investigate the electrochemical behavior of Ru(H2bpp)2(PF6)2 and the interaction between Ru(H2bpp)2(PF6)2 and bovine serum albumin (BSA). In the present of BSA, the oxidation peak current of Ru(H2bpp)2(PF6)2 complex was decreased linearly and the decrease of oxidation peak current of Ru(H2bpp)2(PF6)2 is proportional to BSA concentration from 0.1 to 2.5 mg/L with a detection limit 0.02 mg/L.

  5. Initial DNA interactions of the binuclear threading intercalator Λ,Λ-[μ-bidppz(bipy)4Ru2]4+: an NMR study with [d(CGCGAATTCGCG)]2.

    Science.gov (United States)

    Wu, Lisha; Reymer, Anna; Persson, Cecilia; Kazimierczuk, Krzysztof; Brown, Tom; Lincoln, Per; Nordén, Bengt; Billeter, Martin

    2013-04-22

    Binuclear polypyridine ruthenium compounds have been shown to slowly intercalate into DNA, following a fast initial binding on the DNA surface. For these compounds, intercalation requires threading of a bulky substituent, containing one Ru(II), through the DNA base-pair stack, and the accompanying DNA duplex distortions are much more severe than with intercalation of mononuclear compounds. Structural understanding of the process of intercalation may greatly gain from a characterisation of the initial interactions between binuclear Ru(II) compounds and DNA. We report a structural NMR study on the binuclear Ru(II) intercalator Λ,Λ-B (Λ,Λ-[μ-bidppz(bipy)4Ru2](4+); bidppz = 11,11'-bis(dipyrido[3,2-a:2',3'-c]phenazinyl, bipy = 2,2'-bipyridine) mixed with the palindromic DNA [d(CGCGAATTCGCG)]2. Threading of Λ,Λ-B depends on the presence and length of AT stretches in the DNA. Therefore, the latter was selected to promote initial binding, but due to the short stretch of AT base pairs, final intercalation is prevented. Structural calculations provide a model for the interaction: Λ,Λ-B is trapped in a well-defined surface-bound state consisting of an eccentric minor-groove binding. Most of the interaction enthalpy originates from electrostatic and van der Waals contacts, whereas intermolecular hydrogen bonds may help to define a unique position of Λ,Λ-B. Molecular dynamics simulations show that this minor-groove binding mode is stable on a nanosecond scale. To the best of our knowledge, this is the first structural study by NMR spectroscopy on a binuclear Ru compound bound to DNA. In the calculated structure, one of the positively charged Ru(2+) moieties is near the central AATT region; this is favourable in view of potential intercalation as observed by optical methods for DNA with longer AT stretches. Circular dichroism (CD) spectroscopy suggests that a similar binding geometry is formed in mixtures of Λ,Λ-B with natural calf thymus DNA. The present minor

  6. Interactions between interfacial water and CO adsorbed on Pt and Pt-Ru alloy surfaces under electrochemical conditions: Density-functional theory study

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Juan A. [Department of Chemistry, University of Puerto Rico, San Juan, PR 00931-3346 (Puerto Rico); Ishikawa, Yasuyuki, E-mail: yishikawa@uprrp.ed [Department of Chemistry, University of Puerto Rico, San Juan, PR 00931-3346 (Puerto Rico)

    2010-12-30

    The structural and electronic properties of interfacial water and adsorbed CO on platinum and platinum/ruthenium alloy have been studied via density-functional theory calculations to gain insight into the water-adsorbate interaction under electrochemical conditions. The computational simulations reveal a new interpretation for the interaction of adsorbed CO and water at the electrochemical interfaces. The new interaction model rationalizes the observed quantitative relationship between infrared intensities for adsorbed bridging CO and water molecules that impart a high-frequency O-H stretch, ca. 3630-3660 cm{sup -1} on pure Pt and 3600-3620 cm{sup -1} on PtRu alloy. The theoretical modeling indicates that the observed feature common to both pure Pt and PtRu alloy surfaces is due to interfacial water molecules firmly hydrogen-bonded to bridging CO.

  7. Correlation effects and spin-orbit interaction in Sr{sub 3}Ru{sub 2}O{sub 7}: LDA+DMFT study

    Energy Technology Data Exchange (ETDEWEB)

    Gorelov, Evgeny; Zhang, Guoren; Pavarini, Eva [IAS-3, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2013-07-01

    The layered ruthenates of the Ruddlesden-Popper family Sr{sub n+1}Ru{sub n}O{sub 3n+1} are interesting examples of strongly correlated transition metal compounds. Due to competing kinetic and Coulomb energies, that are of the same order for Ru 4d electrons, these compounds have very rich phase diagram, including Mott-insulator, ferro- and meta-magnetic phases. Among layered ruthenates the bilayered compound Sr{sub 3}Ru{sub 2}O{sub 7} is particularly interesting. It is known to be a paramagnetic metal close to ferro-magnetism and exhibits a metamagnetic behavior in external magnetic field. By using the LDA+DMFT (local-density approximation + dynamical mean-field theory) approach, we study magnetic properties and electron mass renormalization due to correlation effects. In our LDA+DMFT scheme we use maximally-localized Wannier orbitals obtained from Linearized Augmented Plane Wave (LAPW) calculations to build a low-energy Hubbard model for the Ru d bands; we use the weak-coupling CT-quantum Monte Carlo method to solve the quantum impurity problem. We take into account the full rotationally-invariant Coulomb interaction, as well as full on-site self-energy matrix in orbital space with spin-orbit coupling.

  8. Attractive Noncovalent Interactions in the Mechanism of Grubbs Second-Generation Ru Catalysts for Olefin Metathesis.

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yan; Truhlar, Donald G.

    2007-05-10

    Second-generation ruthenium carbenoid catalysts for olefin metathesis are a hundred to a thousand times more active than first-generation catalysts, despite a slower initiation step. A new density functional capable of treating medium-range correlation energy shows that the relative rates of generation of the catalyst are determined by attractive noncovalent interactions.

  9. Quenching of the long-lived Ru(II)bathophenanthroline luminescence for the detection of supramolecular interactions.

    Science.gov (United States)

    Kramer, Rolf A; Kainmüller, Eva K; Flehr, Roman; Kumke, Michael U; Bannwarth, Willi

    2008-07-07

    A feasibility study based on tailor-made peptide sequences for a new robust luminescence probe-system using the long-lived luminescence of a Ru(II)-bathophenanthroline complex in combination with an efficient anthraquinone-type quencher is presented. Due do their high chemical stability, both dyes can be introduced during solid-phase peptide synthesis avoiding post-synthetic labelling. Photophysical measurements revealed an intense quenching of the luminescence of the Ru-complex (65-68%) which was also confirmed by calculations resulting from decay time measurements. The long-lived luminescence allows for a time-gated detection scheme, which can reduce any luminescence contribution from matrix components.

  10. Agostic interaction in the methylidene metal dihydride complexes H2MCH2 (M=Y, Zr, Nb, Mo, Ru, Th, or U).

    Science.gov (United States)

    Roos, Björn O; Lindh, Roland; Cho, Han-Gook; Andrews, Lester

    2007-07-19

    Multiconfigurational quantum chemical methods (complete active space self-consistent field (CASSCF)/second-order perturbation theory (CASPT2)) have been used to study the agostic interaction between the metal atom and H(C) in the methylidene metal dihydride complexes H2MCH2, where M is a second row transition metal or the actinide atoms Th or U. The geometry of some of these complexes is highly irregular due to the formation of a three center bond CH...M, where the electrons in the CH bond are delocalized onto empty or half empty orbitals of d- or f-type on the metal. No agostic interaction is expected when M=Y, where only a single bond with methylene can be formed, or when M=Ru, because of the lack of empty electron accepting metal valence orbitals. The largest agostic interaction is found in the Zr and U complexes.

  11. Interaction of Lambda- and Delta-[Ru(bpy)2(pbmz)](PF6)2 with the oligonucleotide duplex d(CGCGAATTCGCG)2.

    Science.gov (United States)

    Papakyriakou, Athanasios; Malandrinos, Gerasimos; Garoufis, Achilleas

    2006-11-01

    The interaction of the enantiomeric complexes Lambda- and Delta-[Ru(bpy)(2)(pbmz)](PF(6))(2) (bpy=2,2'-bipyridine, pbmz=2-(2'-pyridyl)benzimidazole) with the DNA duplex d(CGCGAATTCGCG)(2) was investigated by means of 2D NMR techniques. The synthesis of the enantiomers was based on the optically pure complexes Lambda- and Delta-[Ru(bpy)(2)(py)(2)](2+) and were characterized by CD and NMR spectroscopy. NMR data indicate that both enantiomers bind weakly to the oligonucleotide, approaching from the minor groove at the centre of the helix. The perturbation of the B-DNA conformation is minor with an apparent absence of enantioselectivity. Molecular modelling calculations in conjunction with the NOE data support the suggestion that more than one binding modes are present. The imidazole amine group of the pbmz ligand is probably hydrogen bonded to the DNA phosphodiesteric backbone at the AATT step, and this may provide an explanation for the diminished enantioselectivity observed.

  12. Convergent study of Ru-ligand interactions through QTAIM, ELF, NBO molecular descriptors and TDDFT analysis of organometallic dyes

    Science.gov (United States)

    Sánchez-Coronilla, Antonio; Sánchez-Márquez, Jesús; Zorrilla, David; Martín, Elisa I.; de los Santos, Desireé M.; Navas, Javier; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Martín-Calleja, Joaquín

    2014-08-01

    We report a theoretical study of a series of Ru complexes of interest in dye-sensitised solar cells, in organic light-emitting diodes, and in the war against cancer. Other metal centres, such as Cr, Co, Ni, Rh, Pd, and Pt, have been included for comparison purposes. The metal-ligand trends in organometallic chemistry for those compounds are shown synergistically by using three molecular descriptors: quantum theory of atoms in molecules (QTAIM), electron localisation function (ELF) and second-order perturbation theory analysis of the natural bond orbital (NBO). The metal-ligand bond order is addressed through both delocalisation index (DI) of QTAIM and fluctuation index (λ) of ELF. Correlation between DI and λ for Ru-N bond in those complexes is introduced for the first time. Electron transfer and stability was also assessed by the second-order perturbation theory analysis of the NBO. Electron transfer from the lone pair NBO of the ligands toward the antibonding lone pair NBO of the metal plays a relevant role in stabilising the complexes, providing useful insights into understanding the effect of the 'expanded ligand' principle in supramolecular chemistry. Finally, absorption wavelengths associated to the metal-to-ligand charge transfer transitions and the highest occupied molecular orbital (HOMO)--lowest unoccupied molecular orbital (LUMO) characteristics were studied by time-dependent density functional theory.

  13. LDA+DMFT study of Ca{sub 2}RuO{sub 4} and Sr{sub 2}RuO{sub 4} using the full on-site Coulomb interaction

    Energy Technology Data Exchange (ETDEWEB)

    Gorelov, Evgeny; Pavarini, Eva [Forschungszentrum Juelich, IFF, 52425 Juelich (Germany); Lichtenstein, Alexander I. [Institute of Theoretical Physics, University Hamburg, 20355 Hamburg (Germany)

    2009-07-01

    The Ca{sub 2-x}Sr{sub x}RuO{sub 4} layered ruthenates display a complex phase diagram. Whereas Sr{sub 2}RuO{sub 4} is a correlated metal, the progressive substitution Sr with Ca leads to a number of structural phase changes. Finally, Ca{sub 2}RuO{sub 4} exhibits Mott transition at T{approx}350 K. In this work we calculate the photoemission spectra of Sr{sub 2}RuO{sub 4} and study the temperature-induced Mott transition in Ca{sub 2}RuO{sub 4}. As a method we use the LDA+DMFT technique. First we construct a material-specific NMTO Wannier basis for the partially filled 4d t{sub 2g} bands and the corresponding three-band t{sub 2g} Hubbard Hamiltonian. Then we solve this model within the DMFT approximation retaining the full self-energy matrix and using the Continuous Time QMC impurity solver. This solver allow us to analyze the role played by the spin-flip terms of the on-site Coulomb vertex.

  14. Al 2O 3 supported Ru catalysts prepared by thermolysis of Ru 3(CO) 12 for catalytic wet air oxidation

    Science.gov (United States)

    Yu, Chaoying; Zhao, Peiqing; Chen, Gexin; Hu, Bin

    2011-06-01

    Low loading catalysts Ru/γ-Al 2O 3 and Ru-Ce/γ-Al 2O 3 were prepared by thermolysis of Ru 3(CO) 12 on γ-Al 2O 3. The catalysts were characterized by XPS, XRD and SEM. Two new Ru species (Ru A and Ru B) were detected during the Ru 3(CO) 12 decomposition process due to chemical interaction with the active OH groups on the surface of Al 2O 3 support, and the reduction of them can lead to more dispersed metallic phases. The sample was completely decomposed at 673 K in H 2, and RuO 2 was formed with minor amounts of Ru 0. When the temperature was increased to 773 K to heat the sample, the ratio of Ru 0 to RuO 2 increased. However, after the addition of CeO 2, only RuO 2 was detected on surface. The catalysts exhibited high activities in Catalytic Wet Air Oxidation (CWAO) of different organic compounds at high concentration such as isopropyl alcohol, phenol, acetic acids and N,N-dimethylformamide, which is attributed to the better dispersion of Ru particles and the addition of CeO 2 further enhanced number of effectively active sites on the cluster-derived catalyst surface.

  15. Combination of ICP-MS, capillary electrophoresis, and their hyphenation for probing Ru(III) metallodrug-DNA interactions.

    Science.gov (United States)

    Foteeva, Lidia S; Matczuk, Magdalena; Pawlak, Katarzyna; Aleksenko, Svetlana S; Nosenko, Sergey V; Karandashev, Vasily K; Jarosz, Maciej; Timerbaev, Andrei R

    2017-03-01

    Determination of the DNA-binding reactivity and affinity is an important part of a successful program for the selection of metallodrug candidates. For such assaying, a range of complementary analytical techniques was proposed and tested here using one of few anticancer metal-based drugs that are currently in clinical trials, indazolium trans-[tetrachloridobis(1H-indazole)ruthenate(III), and a DNA oligonucleotide. A high reactivity of the Ru drug was confirmed in affinity capillary electrophoresis (CE) mode, where adduct formation takes place in situ (i.e., in the capillary filled with an oligonucleotide-containing electrolyte). To further characterize the binding kinetics, a drug-oligonucleotide mixture was incubated for a different period of time, followed by ultrafiltration separation into two different in molecular weight fractions (>3 and ICP-MS), revealing that at least two DNA adducts exist at equilibrium conditions. Using standalone ICP-MS, dominant equilibrium amount of the bound ruthenium was found to occur in a fraction of 5-10 kDa, which includes the oligonucleotide (ca. 6 kDa). Importantly, in all three assays, the drug was used for the first time in in-vitro studies, not in the intact form but as its active species released from the transferrin adduct at simulated cancer cytosolic conditions. This circumstance makes the established analytical platform promising to provide a detailed view on metallodrug targeting, including other possible biomolecules and ex vivo samples.

  16. Comparison of halogen bonding networks with Ru(ii) complexes and analysis of the influence of the XB interactions on their reactivity.

    Science.gov (United States)

    Mosquera, Marta E G; Egido, Irene; Hortelano, Carlos; López-López, María; Gómez-Sal, Pilar

    2017-07-20

    Coordination compounds of formula [Ru(Cl)2(CNR)4] are interesting building blocks for the preparation of halogen bonding supramolecular networks, since the chloride ligand is a good XB acceptor. When using I2 as the XB donor, an unexpected reaction on the ruthenium coordination sphere happens where the chloride ligands are substituted by iodides. The isolation of several intermediates with different substitution degrees and showing XB interactions in a solid state network evidenced the clear influence of the XB species in this unusual reaction process. The extension of the studies to bromine gave the analogous result, i.e. the substitution of the chloride ligands by bromides. Furthermore, changing the organic substituent in the isocyanide ligands from alkyl to aryl does not affect the outcome of the reaction; however the process is faster when the alkyl substituents are present. In the course of the study of these reactions we have isolated a whole range of XB-based networks were interactions such as ClI-I, BrBr-Br, II-I and IBr-Br are present, a systematic comparison of the XB structural features for the different networks isolated and the influence in their reactivity has been performed.

  17. Adsorption of formaldehyde and formyl intermediates on Pt, PtRu-, and PtRuMo-alloy surfaces: A density functional study

    Science.gov (United States)

    Cahyanto, Wahyu Tri; Shukri, Ganes; Agusta, Mohammad Kemal; Kasai, Hideaki

    2013-02-01

    Stable binding configuration for formaldehyde (H2CO) and formyl (HCO) adsorption on Pt, PtRu, and PtRuMo are studied within the frame of density functional theory (DFT). We address this study to investigate the role of Ru and Mo on the binding characteristic of formaldehyde and formyl adsorption with respect to interaction strength and charge analysis. Several binding conformation on all possible surface adsorption sites are considered in determining the most stable adsorption geometry on three surfaces. Our results show that the presence of Ru in PtRu and Mo in PtRuMo stabilize the formaldehyde and formyl, which are indicated by stronger bond strength. Further electronic structure analysis shows that the addition of Ru in PtRu and Mo in PtRuMo modifies the electronic structure of Pt's surface significantly. The presence of both impurities shifted the derived anti-bonding state - which is originally located below the fermi level in pure Pt surface - to be above the fermi level in PtRu and PtRuMo systems. This fact explains the stronger adsorption found on PtRu & PtRuMo as compared to pure Pt surface.

  18. Charge transfer interactions of a Ru(II) dye complex and related ligand molecules adsorbed on Au(111)

    Energy Technology Data Exchange (ETDEWEB)

    Britton, Andrew J.; Weston, Matthew; O' Shea, James N. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Nottingham Nanotechnology and Nanoscience Centre (NNNC), University of Nottingham, Nottingham NG7 2RD (United Kingdom); Taylor, J. Ben; Rienzo, Anna; Mayor, Louise C. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2011-10-28

    The interaction of the dye molecule, N3 (cis-bis(isothiocyanato)bis(2,2{sup '}-bipyridyl-4,4{sup '}-dicarboxylato) -ruthenium(II)), and related ligand molecules with a Au(111) surface has been studied using synchrotron radiation-based electron spectroscopy. Resonant photoemission spectroscopy (RPES) and autoionization of the adsorbed molecules have been used to probe the coupling between the molecules and the substrate. Evidence of charge transfer from the states near the Fermi level of the gold substrate into the lowest unoccupied molecular orbital (LUMO) of the molecules is found in the monolayer RPES spectra of both isonicotinic acid and bi-isonicotinic acid (a ligand of N3), but not for the N3 molecule itself. Calibrated x-ray absorption spectroscopy and valence band spectra of the monolayers reveals that the LUMO crosses the Fermi level of the surface in all cases, showing that charge transfer is energetically possible both from and to the molecule. A core-hole clock analysis of the resonant photoemission reveals a charge transfer time of around 4 fs from the LUMO of the N3 dye molecule to the surface. The lack of charge transfer in the opposite direction is understood in terms of the lack of spatial overlap between the {pi}*-orbitals in the aromatic rings of the bi-isonicotinic acid ligands of N3 and the gold surface.

  19. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Chao [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Yang, Xu [Key Laboratory of Renewable Energy, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou (China); Yang, Hui; Huang, Peiyan; Song, Huiyu [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China); Liao, Shijun, E-mail: chsjliao@scut.edu.cn [The Key Laboratory of Fuel Cell Technology of Guangdong Province and The Key Laboratory for New Energy of Guangdong Universities, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou (China)

    2014-10-01

    Graphical abstract: The addition of Ru could significantly improve the performance of the mesoporous silica nanoparticles supported PdRu/MSN catalyst, which showed over 5 times higher mass activity than the mono-Pd/MSN towards the liquid-phase hydrogenation of phenol. The improved dispersion and the electronic interaction contributed to the enhanced catalytic activity for the catalyst towards phenol hydrogenation. - Highlights: • PdRu bimetal catalyst supported on mesoporous silica nanoparticles was prepared. • The average sizeof PdRu alloy is smaller than that of mono-Pd. • The addition of Ru to Pd modulates the electronic properties between Pd and Ru. • PdRu/MSN catalyst shows superior activity on phenol hydrogenation than Pd/MSN. • PdRu/MSN catalyst shows good selectivity for cyclohexanol to some extent. - Abstract: A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation–hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  20. The Nanostructuring of Atomically Flat Ru(0001) upon Oxidation and Reduction

    Science.gov (United States)

    Goriachko, A.; Over, H.

    2016-12-01

    The O/Ru(0001) system is widely studied due to its rich phase variety of various stoichiometry and atomic arrangements, including the formation of a RuO2/Ru(0001) oxide layer. Apart from homogeneous ruthenium surfaces in certain oxidation states, also strongly heterogeneous surfaces can exist due to oxidation state's variation at the nanoscale. We report on a scanning tunneling microscopy (STM) study of the nanostructuring of the oxidized Ru(0001) surface as a result of its interaction with molecular oxygen at elevated temperatures and subsequent reduction of a resulting RuO2 film by CO or HCl molecules from the gas phase in high-vacuum environment.

  1. $\\it{Ab-initio}$ calculations of electric field gradient in Ru compounds and their implication on the nuclear quadrupole moments of $^{99}$Ru and $^{101}$Ru

    Indian Academy of Sciences (India)

    S N MISHRA

    2017-08-01

    The nuclear quadrupole moments, $\\mathcal{Q}$, for the ground and first excited states in $^{99}$Ru and ground state of $^{101}$Ru have been determined by comparing the experimentally observed quadrupole interaction frequencies $\\mathcal{ν_{Q}}$ with calculated electric field gradient (EFG) for a large number of Ru-based compounds. The $\\it{ab-initio}$ calculations of EFG were performed using the all-electron augmented plane wave + local orbital (APW + lo) method of the density functional theory (DFT). From the slope of the linear correlation between theoretically calculated EFGs and experimentally observed $\\mathcal{ν_{Q}}$, we obtain the quadrupole moment for the $(5/2^{+})$ ground state in $^{99}$Ru and $^{101}$Ru as 0.0734(17) b and 0.431(14) b respectively, showing excellent agreement with the values reported in literature. For $3/2^{+}$, the quadrupole moment of the first excited state in $^{99}$Ru is obtained as +0.203(3) b, which is considerably lower than the commonly accepted literature value of +0.231(12) b. The results presented in this paper would be useful for the precise determination of quadrupole moment of high spin states in other Ru isotopes and is likely to stimulate further shell model calculations for an improved understanding of nuclear shape in these nuclei.

  2. Ab-initio calculations of electric field gradient in Ru compounds and their implication on the nuclear quadrupole moments of ^{99}Ru and ^{101}Ru

    Science.gov (United States)

    Mishra, S. N.

    2017-08-01

    The nuclear quadrupole moments, Q, for the ground and first excited states in ^{99}Ru and ground state of ^{101}Ru have been determined by comparing the experimentally observed quadrupole interaction frequencies ν _Q with calculated electric field gradient (EFG) for a large number of Ru-based compounds. The ab-initio calculations of EFG were performed using the all-electron augmented plane wave + local orbital (APW + lo) method of the density functional theory (DFT). From the slope of the linear correlation between theoretically calculated EFGs and experimentally observed ν _Q, we obtain the quadrupole moment for the (5/2^+) ground state in ^{99}Ru and ^{101}Ru as 0.0734(17) b and 0.431(14) b respectively, showing excellent agreement with the values reported in literature. For 3/2^+, the quadrupole moment of the first excited state in ^{99}Ru is obtained as +0.203(3) b, which is considerably lower than the commonly accepted literature value of +0.231(12) b. The results presented in this paper would be useful for the precise determination of quadrupole moment of high spin states in other Ru isotopes and is likely to stimulate further shell model calculations for an improved understanding of nuclear shape in these nuclei.

  3. Substrate-mediated enhanced activity of Ru nanoparticles in catalytic hydrogenation of benzene

    KAUST Repository

    Liu, Xin

    2012-01-01

    The impact of carbon substrate-Ru nanoparticle interactions on benzene and hydrogen adsorption that is directly related to the performance in catalytic hydrogenation of benzene has been investigated by first-principles based calculations. The stability of Ru 13 nanoparticles is enhanced by the defective graphene substrate due to the hybridization between the dsp states of the Ru 13 particle with the sp 2 dangling bonds at the defect sites. The local curvature formed at the interface will also raise the Ru atomic diffusion barrier, and prohibit the particle sintering. The strong interfacial interaction results in the shift of averaged d-band center of the deposited Ru nanoparticle, from -1.41 eV for a freestanding Ru 13 particle, to -1.17 eV for the Ru/Graphene composites, and to -1.54 eV on mesocellular foam carbon. Accordingly, the adsorption energies of benzene are increased from -2.53 eV for the Ru/mesocellular foam carbon composites, to -2.62 eV on freestanding Ru 13 particles, to -2.74 eV on Ru/graphene composites. A similar change in hydrogen adsorption is also observed, and all these can be correlated to the shift of the d-band center of the nanoparticle. Thus, Ru nanoparticles graphene composites are expected to exhibit both high stability and superior catalytic performance in hydrogenation of arenes. © 2012 The Royal Society of Chemistry.

  4. Oxidation of Mg adsorbed on Ru(001): A photoemission study

    Energy Technology Data Exchange (ETDEWEB)

    Malik, I.J.; Hrbek, J. (Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)); Shek, M. (National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)); Bzowski, A.; Kristof, P.; Sham, T.K. (Department of Chemistry, University of Western Ontario, London, Ontario NA6 5B7 (Canada))

    1992-07-01

    We studied the interaction of oxygen with Mg overlayers adsorbed on Ru(001). Soft x-ray synchrotron radiation was used to explore photoemission from the valence band, the O 2{ital p}, O 2{ital s}, and Mg 2{ital p} levels, as well as intra- and interatomic Auger processes. The photoemission results are complemented by thermal desorption data. The O/Mg/Ru system shows photoemission features characteristic of molecular orbitals of a dioxygen species.

  5. Electronic structures and vibrational properties of coronene on Ru(0001): first-principles study

    Institute of Scientific and Technical Information of China (English)

    Zhang Yu-Yang; Du Shi-Xuan; Gao Hong-Jun

    2012-01-01

    We calculate the configurations,electronic structures,vibrational properties at the coronene/Ru(0001) interface,and adsorption of a single Pt atom on coronene/Ru(0001) based on density functional theory calculations.The geometric structures and electronic structures of the coronene on Ru(0001) are compared with those of the graphene/Ru(0001).The results show that the coronene/Ru(0001) can be a simplified model system used to describe the interaction between graphene and ruthenium.Further calculations of the vibrational properties of coronene molecule adsorbed on Ru(0001)suggest that the phonon properties of differently corrugated regions of graphene on Ru(0001) are different.This model system is also used to investigate the selective adsorption of Pt atoms on graphene/Ru(0001).The configurations of Pt on coronene/Ru(0001) with the lowest binding energy give clues to explain the experimental observation that a Pt cluster selectively adsorbs on the second highest regions of graphene/Ru(0001).This work provides a simple model for understanding the adsorption properties and vibrational properties of graphene on Ru(0001) substrate.

  6. Full optimized reaction space model for quantum chemical reaction calculations. Definition, applications, and the IntraAtomic correlation correction extension. [H/sub 2/ exchange between ethane and ethylene; gas-phase ozonolysis

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, M.W.

    1982-12-01

    The Full Optimized Reaction Space (FORS) model is used for the theoretical calculation of molecular potential energy surfaces involved in chemical reactions. The FORS model is applied to two polyatomic reactions: the dihydrogen exchange between ethane and etylene, and the formation and dissolution of dioxirane and dioxymethane. The former reaction is found to possess a high barrier, in spite of its symmetry allowed nature. The latter reaction involves significant configuration mixing as methylene and oxygen react to form, successively, dioxirane, dioxymethane, and hydrogen and carbon dioxide. Finally, FORS wavefunctions can be expressed in terms of a basis of antisymmetrized products of atomic state functions, using the predominantly atomic projected localized orbitals. The atoms in molecules analysis permits the incorporation of data from atomic spectra into the molecular Hamiltonian to achieve the IntraAtomic Correlation Correction (IACC). The IACC scheme is illustrated for a few small diatomics (H/sub 2/, NH, F/sub 2/), and is shown to yield more accurate results than the uncorrected FORS wavefunctions.

  7. Nitrogen Scattering at Ru Surfaces

    NARCIS (Netherlands)

    Zaharia, T.; Ueta, H.; Kleyn, A.W.; Gleeson, M.A.

    2013-01-01

    Results on the scattering of hyperthermal N2 molecules from bare and N-covered Ru(0001) surfaces are presented. These are compared with Ar scattering from the same surfaces as a reference nonreactive system. In the case of bare Ru(0001) the measured angular distributions are consistent with scatteri

  8. Nitrogen Scattering at Ru Surfaces

    NARCIS (Netherlands)

    Zaharia, T.; Ueta, H.; Kleyn, A. W.; Gleeson, M. A.

    2013-01-01

    Results on the scattering of hyperthermal N2 molecules from bare and N-covered Ru(0001) surfaces are presented. These are compared with Ar scattering from the same surfaces as a reference non-reactive system. In the case of bare Ru(0001) the measured angular distributions are consistent with scatter

  9. Nitrogen Scattering at Ru Surfaces

    NARCIS (Netherlands)

    Zaharia, T.; Ueta, H.; Kleyn, A.W.; Gleeson, M.A.

    2013-01-01

    Results on the scattering of hyperthermal N-2 molecules from bare and N-covered Ru(0001) surfaces are presented. These are compared with Ar scattering from the same surfaces as a reference non-reactive system. In the case of bare Ru(0001) the measured angular distributions are consistent with scatte

  10. Reactions of ethanol on Ru

    NARCIS (Netherlands)

    Sturm, Jacobus Marinus; Liu, Feng; Lee, Christopher James; Bijkerk, Frederik

    2012-01-01

    The adsorption and reactions of ethanol on Ru(0001) were studied with temperatureprogrammed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS). Ethanol was found to adsorb intact onto Ru(0001) below 100 K. Heating to 250 K resulted in formation of ethoxy groups, which undergo

  11. A Renewable and Ultrasensitive Electrochemiluminescence Immunosenor Based on Magnetic RuL@SiO2-Au~RuL-Ab2 Sandwich-Type Nano-Immunocomplexes

    Directory of Open Access Journals (Sweden)

    Ning Gan

    2011-08-01

    Full Text Available An ultrasensitive and renewable electrochemiluminescence (ECL immunosensor was developed for the detection of tumor markers by combining a newly designed trace tag and streptavidin-coated magnetic particles (SCMPs. The trace tag (RuL@SiO2-Au~RuL-Ab2 was prepared by loading Ru(bpy32+(RuL-conjuged secondary antibodies (RuL-Ab2 on RuL@SiO2 (RuL-doped SiO2 doped Au (RuL@SiO2-Au. To fabricate the immunosensor, SCMPs were mixed with biotinylated AFP primary antibody (Biotin-Ab1, AFP, and RuL@SiO2-Au~RuL-Ab2 complexes, then the resulting SCMP/Biotin-Ab1/AFP/RuL@SiO2-Au~RuL-Ab2 (SBAR sandwich-type immunocomplexes were absorbed on screen printed carbon electrode (SPCE for detection. The immunocomplexes can be easily washed away from the surface of the SPCE when the magnetic field was removed, which made the immunosensor reusable. The present immunosensor showed a wide linear range of 0.05–100 ng mL–1 for detecting AFP, with a low detection limit of 0.02 ng mL–1 (defined as S/N = 3. The method takes advantage of three properties of the immunosensor: firstly, the RuL@SiO2-Au~RuL-Ab2 composite exhibited dual amplification since SiO2 could load large amount of reporter molecules (RuL for signal amplification. Gold particles could provide a large active surface to load more reporter molecules (RuL-Ab2. Accordingly, through the ECL response of RuL and tripropylamine (TPA, a strong ECL signal was obtained and an amplification analysis of protein interaction was achieved. Secondly, the sensor is renewable because the sandwich-type immunocomplexes can be readily absorbed or removed on the SPCE’s surface in a magnetic field. Thirdly, the SCMP modified probes can perform the rapid separation and purification of signal antibodies in a magnetic field. Thus, the present immunosensor can simultaneously realize separation, enrichment and determination. It showed potential application for the detection of AFP in human sera.

  12. Methanol Electro-Oxidation on Pt-Ru Alloy Nanoparticles Supported on Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yangchuan Xing

    2009-09-01

    Full Text Available Carbon nanotubes (CNTs have been investigated in recent years as a catalyst support for proton exchange membrane fuel cells. Improved catalyst activities were observed and attributed to metal-support interactions. We report a study on the kinetics of methanol electro-oxidation on CNT supported Pt-Ru alloy nanoparticles. Alloy catalysts with different compositions, Pt53Ru47/CNT, Pt69Ru31/CNT and Pt77Ru23/CNT, were prepared and investigated in detail. Experiments were conducted at various temperatures, electrode potentials, and methanol concentrations. It was found that the reaction order of methanol electro-oxidation on the PtRu/CNT catalysts was consistent with what has been reported for PtRu alloys with a value of 0.5 in methanol concentrations. However, the electro-oxidation reaction on the PtRu/CNT catalysts displayed much lower activation energies than that on the Pt-Ru alloy catalysts unsupported or supported on carbon black (PtRu/CB. This study provides an overall kinetic evaluation of the PtRu/CNT catalysts and further demonstrates the beneficial role of CNTs.

  13. Kinetic study of methanol oxidation on Pt2Ru3/C catalyst in the alkaline media

    Directory of Open Access Journals (Sweden)

    A. V. TRIPKOVIC

    2007-11-01

    Full Text Available The interaction of acridine orange (AO with double-stranded (ds The electrochemical oxidation of methanol in NaOH solution was examined on a thin film Pt2Ru3/C electrode. The XRD pattern revealed that the Pt2Ru3 alloy consisted of a solid solution of Ru in Pt and a small amount of Ru or a solid solution of Pt in Ru. It was shown that in alkaline solution, the difference in activity between Pt/C and Pt2Ru3/C is significantly smaller than in acid solution. It is proposed that the reaction follows a quasi bifunctional mechanism. The kinetic parameters indicated that the chemical reaction between adsorbed COad and OHad species could be the rate limiting step.

  14. Communication between remote moieties in linear Ru-Ru-Ru trimetallic cyanide-bridged complexes.

    Science.gov (United States)

    Pieslinger, German E; Albores, Pablo; Slep, Leonardo D; Coe, Benjamin J; Timpson, Cliff J; Baraldo, Luis M

    2013-03-18

    In this article, we report the structural, spectroscopic, and electrochemical properties of the cyanide-bridged complex salts trans-[(NC)Ru(II)(L)4(μ-CN)Ru(II)(py)4Cl]PF6 and trans-[Ru(II)(L)4{(μ-CN)Ru(II)(py)4Cl}2](PF6)2 (L = pyridine or 4-methoxypyridine). The mixed-valence forms of these compounds show a variety of metal-to-metal charge-transfer bands, including one arising from charge transfer between the remote ruthenium units. The latter is more intense when L = 4-methoxypyridine and points to the role of the bridging ruthenium unit in promoting mixing between the dπ orbitals of the terminal fragments.

  15. Hydrogen mediated transport of Sn to Ru film surface

    NARCIS (Netherlands)

    Faradzhev, N.; Sidorkin, V.

    2009-01-01

    The authors report on the interaction of atomic hydrogen with Sn and thin Ru film at room temperature. The study is done using a combination of photoelectron and low energy ion scattering spectroscopies as well as scanning electron microscopy. The adsorption of hydrogen on a Sn surface leads to the

  16. Hydrogen mediated transport of Sn to Ru film surface

    NARCIS (Netherlands)

    Faradzhev, N.; Sidorkin, V.

    2009-01-01

    The authors report on the interaction of atomic hydrogen with Sn and thin Ru film at room temperature. The study is done using a combination of photoelectron and low energy ion scattering spectroscopies as well as scanning electron microscopy. The adsorption of hydrogen on a Sn surface leads to the

  17. Bottom-up fabrication of graphene nanostructures on Ru(1010).

    Science.gov (United States)

    Song, Junjie; Zhang, Han-jie; Cai, Yiliang; Zhang, Yuxi; Bao, Shining; He, Pimo

    2016-02-01

    Investigations on the bottom-up fabrication of graphene nanostructures with 10, 10'-dibromo-9, 9'-bianthryl (DBBA) as a precursor on Ru(1010) were carried out using scanning tunnelling microscopy (STM) and density functional theory (DFT) calculations. Upon annealing the sample at submonolayer DBBA coverage, N = 7 graphene nanoribbons (GNRs) aligned along the [1210] direction form. Higher DBBA coverage and higher annealing temperature lead to the merging of GNRs into ribbon-like graphene nanoflakes with multiple orientations. These nanoflakes show different Moiré patterns, and their structures were determined by DFT simulations. The results showed that GNRs possess growth preference on the Ru(1010) substrate with a rectangular unit cell, and GNRs with armchair and zigzag boundaries are obtainable. Further DFT calculations suggest that the interaction between graphene and the substrate controls the orientations of the graphene overlayer and the growth of graphene on Ru(1010).

  18. Insights into the Intramolecular Properties of η6-Arene-Ru-Based Anticancer Complexes Using Quantum Calculations

    Directory of Open Access Journals (Sweden)

    Adebayo A. Adeniyi

    2013-01-01

    Full Text Available The factors that determine the stability and the effects of noncovalent interaction on the η6-arene ruthenium anticancer complexes are determined using DFT method. The intramolecular and intra-atomic properties were computed for two models of these half-sandwich ruthenium anticancer complexes and their respective hydrated forms. The results showed that the stability of these complexes depends largely on the network of hydrogen bonds (HB, strong nature of charge transfer, polarizability, and electrostatic energies that exist within the complexes. The hydrogen bonds strength was found to be related to the reported anticancer activities and the activation of the complexes by hydration. The metal–ligand bonds were found to be closed shell systems that are characterised by high positive Laplacian values of electron density. Two of the complexes are found to be predominantly characterised by LMCT while the other two are predominately characterised by MLCT.

  19. Ternary Pt-Ru-Ni catalytic layers for methanol electrooxidation prepared by electrodeposition and galvanic replacement

    Directory of Open Access Journals (Sweden)

    Athanasios ePapaderakis

    2014-06-01

    Full Text Available Ternary Pt-Ru-Ni deposits on glassy carbon substrates, Pt-Ru(Ni/GC, have been formed by initial electrodeposition of Ni layers onto glassy carbon electrodes, followed by their partial exchange for Pt and Ru, upon their immersion into equimolar solutions containing complex ions of the precious metals. The overall morphology and composition of the deposits has been studied by SEM microscopy and EDS spectroscopy. Continuous but nodular films have been confirmed, with a Pt÷Ru÷Ni % bulk atomic composition ratio of 37÷12÷51 (and for binary Pt-Ni control systems of 47÷53. Fine topographical details as well as film thickness have been directly recorded using AFM microscopy. The composition of the outer layers as well as the interactions of the three metals present have been studied by XPS spectroscopy and a Pt÷Ru÷Ni % surface atomic composition ratio of 61÷12÷27 (and for binary Pt-Ni control systems of 85÷15 has been found, indicating the enrichment of the outer layers in Pt; a shift of the Pt binding energy peaks to higher values was only observed in the presence of Ru and points to an electronic effect of Ru on Pt. The surface electrochemistry of the thus prepared Pt-Ru(Ni/GC and Pt(Ni/GC electrodes in deaerated acid solutions (studied by cyclic voltammetry proves the existence of a shell consisting exclusively of Pt-Ru or Pt. The activity of the Pt-Ru(Ni deposits towards methanol oxidation (studied by slow potential sweep voltammetry is higher from that of the Pt(Ni deposit and of pure Pt; this enhancement is attributed both to the well-known Ru synergistic effect due to the presence of its oxides but also (based on the XPS findings to a modification effect of Pt electronic properties.

  20. Round table on RU486.

    Science.gov (United States)

    Shallat, L

    1993-01-01

    As a non-invasive means of early abortion, RU-486 has the potential to increase women's reproductive options; at the same time, the "abortion pill" has stimulated debate about the ethics and safety of new medical technologies. When combined with a prostaglandin (PG), the success rate for RU-486 is 96% for pregnancies of up to 9 weeks' gestation. In France, over 120,000 women have used RU-486/PG to terminate pregnancy, and this regimen is now used in about 25% of abortions. Clinical trials of RU-486 are underway in Cuba, China, India, Singapore, and Zambia. The Program for Appropriate Technology has identified four considerations for introducing RU-486 to developing countries: whether abortion or menstrual regulation is legal; whether women find the method acceptable and can comply with the multiple visit treatment regimen; whether the health infrastructure can support safe method use, including prevention of misuse and provision of appropriate medical backup personnel and facilities; and whether the cost of the regimen is affordable to individuals and/or programs --conditions unlikely to be met in most such countries. Ideal would be development of a medical abortifacient that is single dose and the lowest possible dose of each drug, provokes miscarriage within a more predictable time frame with less acute and prolonged bleeding, is safe and effective beyond two months, has minimal side effects, and maximizes short-term safety and minimizes long-term effects. Technological advances are being undermined, however, by political and religious attacks on the method. Even some feminists have expressed concerns about potential long-term effects of RU-486 use.

  1. High-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles for phenol hydrogenation

    Science.gov (United States)

    Huang, Chao; Yang, Xu; Yang, Hui; Huang, Peiyan; Song, Huiyu; Liao, Shijun

    2014-10-01

    A high-performance PdRu bimetallic catalyst supported on mesoporous silica nanoparticles (MSN), PdRu/MSN, was prepared by a facile impregnation-hydrogen reduction method. It was found that PdRu/MSN showed 5 times higher activity than that of Pd/MSN towards the liquid-phase hydrogenation of phenol. The catalysts were characterized comprehensively by multiple techniques, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature program reduction (TPR). It was revealed that adding Ru could effectively improve the Pd dispersion and promote the electronic interaction between the Pd and Ru, both of which contribute to enhancing the catalytic activity.

  2. Effect of Ru thickness on spin pumping in Ru/Py bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Behera, Nilamani; Singh, M. Sanjoy; Chaudhary, Sujeet; Pandya, Dinesh K., E-mail: dkpandya@physics.iitd.ac.in; Muduli, P. K. [Department of Physics, Thin Film Laboratory, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2015-05-07

    We report the effect of Ru thickness (t{sub Ru}) on ferromagnetic resonance (FMR) line-width of Ru(t{sub Ru})/Py(23 nm) bilayer samples grown on Si(100)/SiO{sub 2} substrates at room temperature by magnetron sputtering. The FMR line-width is found to vary linearly with frequency for all thicknesses of Ru, indicating intrinsic origin of damping. For Ru thicknesses below 15 nm, Gilbert-damping parameter, α is almost constant. We ascribe this behavior to spin back flow that is operative for Ru thicknesses lower than the spin diffusion length in Ru, λ{sub sd}. For thicknesses >15 nm (>λ{sub sd}), the damping constant increases with Ru thickness, indicating spin pumping from Py into Ru.

  3. DFT Simulation of Structural and Optical Properties of 9-Aminoacridine Half-Sandwich Ru(II), Rh(III), and Ir(III) Antitumoral Complexes and Their Interaction with DNA.

    Science.gov (United States)

    Cerón-Carrasco, José Pedro; Ruiz, José; Vicente, Consuelo; de Haro, Concepción; Bautista, Delia; Zúñiga, José; Requena, Alberto

    2017-08-08

    In this work, we use DFT-based methods to simulate the chemical structures, optical properties, and interaction with DNA of a recently synthesized chelated C^N 9-aminoacridine arene Ru(II) anticancer agent and two new closely related Rh(III) and Ir(III) complexes using DFT-based methods. Four chemical models and a number of theoretical approaches, which representatively include the PBE0, B97D, ωB97X, ωB97X-D, M06, and M06-L density functionals and the LANL2DZ, def2-SVP, and def2-TZVP basis sets, are tested. The best overall accuracy/cost performance for the optimization process is reached at the ωB97X-D/def2-SVP and M06/def2-SVP levels of theory. Inclusion of explicit solvent molecules (CHCl3) further refines the geometry, while taking into account the crystal network gives no significant improvements of the computed bond distances and angles. The analysis of the excited states reveals that the M06 level matches better the experimental absorption spectra, compared to ωB97X-D. The use of the M06/def2-SVP approach is therefore a well-balanced method to study theoretically the bioactivity of this type of antitumoral complexes, so we couple this TD-DFT approach to molecular dynamics simulations in order to assess their reactivity with DNA. The reported results demonstrate that these drugs could be used to inject electrons into DNA, which might broaden their applications in photoactivated chemotherapy and as new materials for DNA-based electrochemical nanodevices.

  4. Efeitos auditivos da exposição combinada: interação entre monóxido de carbono, ruído e tabagismo Auditory effects of combined exposure: interaction between carbon monoxide, noise and smoking

    Directory of Open Access Journals (Sweden)

    Débora Gonçalves Ferreira

    2012-12-01

    Full Text Available OBJETIVO: Analisar os efeitos auditivos da exposição combinada ao monóxido de carbono (CO e ao ruído, e o impacto do tabagismo. MÉTODOS: Participaram da pesquisa 80 trabalhadores fumantes e não fumantes, do gênero masculino, oriundos de uma empresa siderúrgica, sendo que 40 estavam expostos ao CO e ao ruído e 40 somente ao ruído. Realizou-se análise retrospectiva dos dados referentes aos riscos ambientais (CO e ruído e das informações contidas nos prontuários médicos relacionadas à saúde auditiva e às concentrações biológicas do CO no sangue (COHb. Analisou-se a audiometria tonal de referência e a última, e os limiares auditivos em função do tabagismo, do tipo de exposição (CO e ruído ou somente ao ruído, do tempo de exposição, do nível de ruído e da idade. RESULTADOS: Tanto a concentração de CO como os níveis de ruído encontraram-se acima do limite de tolerância previsto na norma regulamentadora de número 15 do Ministério do Trabalho. O grupo exposto ao CO e ao ruído apresentou mais casos de PAIR (22,5%, comparativamente ao grupo exposto somente ao ruído (7,5% e também apresentou piora significativa nos limiares auditivos de 3, 4 e 6 kHz. Foram encontradas diferenças significativas entre a idade, o tempo de serviço, o tipo de exposição, o nível de ruído e o hábito de fumar influenciando nos limiares auditivos dos participantes. O hábito de fumar potencializou o efeito tanto do CO quanto do ruído no sistema auditivo. CONCLUSÃO: Efeitos auditivos significativos foram identificados na audição dos trabalhadores de uma siderúrgica expostos ao CO.PURPOSE: To analyze the auditory effects of the combined exposure to carbon monoxide (CO and noise, and the impact of smoking. METHODS: Participants were 80 male workers, smokers and non-smokers, from a steel industry - 40 exposed to CO and noise simultaneously, and 40 exposed only to noise. A retrospective data analysis was conducted regarding the

  5. Study of transient luminescence of three kinds of Ru complexes bound to DNA

    Institute of Scientific and Technical Information of China (English)

    ZHU WeiLing; LIU XueWen; WANG Hui; YU HuiJuan; LI AiZheng; CHAO Hui; ZHENG KangCheng; JI LiangNian

    2008-01-01

    The transient luminescence of three kinds of ruthenium complexes [Ru(bpy)2(7-CH3-dppz)]2+, [Ru(bpy)2(7-F-dppz)]2+ and [Ru(phen)2(7-F-dppz)]2+ bound to calf thy-mus DNA (ctDNA) has been studied by using the time-resolved spectroscopy. The results show that the luminescence is due to the radiative decay from the charge-transfer states to the ground state. By the Interaction with DNA, the radla-tiveless rate of the photoexcited Ru complex molecules decreases, which results In the increase of luminescence lifetime and efficiency. The structure of the Ru com-plex has an important impact on the interaction with DNA. The [Ru(bpy)2(7-CH3-dppz)]2+shows the longest luminescence lifetime (about 382 ns), while the [Ru(bpy)2(7-F-dppz)]2+ shows the shortest lifetime (about 65 ns). The possible origin of the luminescence dynamics is discussed.

  6. Study of transient luminescence of three kinds of Ru complexes bound to DNA

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The transient luminescence of three kinds of ruthenium complexes [Ru(bpy)2(7-CH3-dppz)]2+, [Ru(bpy)2(7-F-dppz)]2+ and [Ru(phen)2(7-F-dppz)]2+ bound to calf thy-mus DNA (ctDNA) has been studied by using the time-resolved spectroscopy. The results show that the luminescence is due to the radiative decay from the charge-transfer states to the ground state. By the interaction with DNA, the radia-tiveless rate of the photoexcited Ru complex molecules decreases, which results in the increase of luminescence lifetime and efficiency. The structure of the Ru com-plex has an important impact on the interaction with DNA. The [Ru(bpy)2(7-CH3-dppz)]2+ shows the longest luminescence lifetime (about 382 ns), while the [Ru(bpy)2(7-F-dppz)]2+ shows the shortest lifetime (about 65 ns). The possible origin of the luminescence dynamics is discussed.

  7. Laser-Induced Fluorescence Spectroscopy of Two Ruthenium-Bearing Molecules: RuF and RuCl

    Science.gov (United States)

    Zarringhalam, Hanif; Adam, Allan G.; Linton, Colan; Tokaryk, Dennis W.

    2017-06-01

    This work extends the electronic spectroscopy of RuF, and reports on what we believe is the first observation of RuCl. Both molecules have been created in a laser-ablation molecular beam apparatus at UNB, and their spectra have been detected by laser-induced fluorescence. In the low-resolution survey of RuF from 400 to 770 nm, five bands were detected in the blue, green and infrared regions of the electromagnetic spectrum. Four of them were rotationally analyzed from high-resolution data. The three bands in the green region are associated with the ^4Γ_{11/2}-X^4Φ_{9/2} system first observed by Steimle et al. A new ^4Δ_{7/2}-X^4Φ_{9/2} transition in the blue region was also detected. Two high-resolution bands of RuCl were rotationally analyzed, and the ground state was also found to be X^4Φ_{9/2}. The data provide detailed structural information about the molecules, such as bond lengths, vibrational frequencies, isotopic structure, spin-orbit interactions and hyperfine interactions. T. C. Steimle, W. Virgo and T. Ma, J. Chem. Phys. 124 024309 (2006).

  8. CO chemisorption and dissociation at high coverages during CO hydrogenation on Ru catalysts.

    Science.gov (United States)

    Loveless, Brett T; Buda, Corneliu; Neurock, Matthew; Iglesia, Enrique

    2013-04-24

    Density functional theory (DFT) and infrared spectroscopy results are combined with mechanism-based rate equations to assess the structure and thermodynamics of chemisorbed CO (CO*) and its activation during Fischer-Tropsch synthesis (FTS). CO* binding becomes weaker with increasing coverage on Ru(0001) and Ru201 clusters, but such decreases in binding energy occur at higher coverages on Ru201 clusters than on Ru(0001) surfaces (CO*/Ru = 1.55 to 0.75); such differences appear to reflect weaker repulsive interactions on the curved surfaces prevalent on small Ru201 clusters. Ru201 clusters achieve stable supramonolayer coverages (CO*/Ru > 1) by forming geminal dicarbonyls at low-coordination corner/edge atoms. CO* infrared spectra on Ru/SiO2 (~7 nm diameter) detect mobile adlayers that anneal into denser structures at saturation. Mechanism-based FTS rate equations give activation energies that reflect the CO*-saturated surfaces prevalent during catalysis. DFT-derived barriers show that CO* predominantly reacts at (111) terraces via H-assisted reactions, consistent with measured effects of H2 and CO pressures and cluster size effects on rates and O-rejection selectivities. Barriers are much higher for unassisted CO* dissociation on (111) terraces and low-coordination atoms, including step-edge sites previously proposed as active sites for CO* dissociation during FTS. DFT-derived barriers indicate that unassisted CO* dissociation is irreversible, making such steps inconsistent with measured rates. The modest activation barriers of H-assisted CO* dissociation paths remove a requirement for special low-coordination sites for unassisted CO* activation, which is inconsistent with higher rates on larger clusters. These conclusions seem generally applicable to Co, Fe, and Ru catalysts, which show similar FTS rate equations and cluster size effects. This study also demonstrates the feasibility and relevance of DFT treatments on the curved and crowded cluster surfaces where

  9. Comparative angle-resolved photoemission spectroscopy study of CaRuO3 and SrRuO3 thin films: Pronounced spectral weight transfer and possible precursor of lower Hubbard band

    Science.gov (United States)

    Yang, H. F.; Fan, C. C.; Liu, Z. T.; Yao, Q.; Li, M. Y.; Liu, J. S.; Jiang, M. H.; Shen, D. W.

    2016-09-01

    In the prototypical 4 d system (Sr ,Ca ) RuO3 , the degree and origin of electron correlations, and how they correlate with physical properties, still remain elusive, though extensive studies have been performed. In this work we present a comparative electronic structure study of high-quality epitaxial CaRuO3 and SrRuO3 thin films, by means of reactive molecular beam epitaxy and in situ angle-resolved photoemission spectroscopy. We found that while SrRuO3 possesses sharp features signaling the Fermi liquid state, the isostructural CaRuO3 exhibits broad features and its spectral weight is markedly transferred from the Fermi level to -1.2 eV forming a "hump" structure which resembles the Mott-Hubbard system (Sr ,Ca ) VO3 . We suggest that this hump is the precursor of the lower Hubbard band, and the U /W (U and W represent the on-site Coulomb interactions and bandwidth, respectively) of our CaRuO3 thin film is much larger than that of SrRuO3. In addition, we discuss the origin of electron correlations as well as the ferromagnetism in SrRuO3 which is absent in CaRuO3. Our findings put constraints on future studies, and also show that perovskite ruthenates are indeed an experimentally tunable system for the study of electron correlations.

  10. Production of ultrapure hydrogen in a Pd-Ag membrane reactor using Ru/La{sub 2}O{sub 3} catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Faroldi, B.; Carrara, C.; Lombardo, E.A.; Cornaglia, L.M. [Instituto de Investigaciones en Catalisis y Petroquimica (FIQ, UNL-CONICET), Santiago del Estero, 2829-3000 Santa Fe (Argentina)

    2007-03-01

    Ru catalysts supported on lanthanum oxide with different loadings were prepared by wet impregnation. These solids were characterized by laser Raman spectroscopy (LSR), XPS, XRD and TPR. The catalytic activity toward hydrogen production through the dry reforming of methane was determined in a fixed-bed reactor and a membrane reactor. The reaction rate expressed per gram of Ru decreased when the metal loading increased. In the Pd-Ag membrane reactor, when the sweep gas flow rate (SG) increased, the conversions overcame the equilibrium values and the difference between CH{sub 4} and CO{sub 2} conversions decreased. Both Ru(0.6) and Ru(1.2) catalysts were able to restore the equilibrium for the dry reforming reaction up to values of SG = 30 ml min{sup -1}; Ru(0.6) was the most effective catalyst. By employing a CO{sub 2}/CH{sub 4} 1 and a SG of 0.05 mmol s{sup -1}, both a high H{sub 2} permeation flux of 5.68 x 10{sup -7} mol s{sup -1} m{sup -2} and a hydrogen recovery of 80% were obtained. Both the TPR and the Raman spectroscopy data indicated the presence of Ru(III) strongly interacting with La. Significantly, this observation was further confirmed by the appearance of Ru(III) on the surface. When the Ru content increased, the higher Ru 3d binding energy component was proposed as arising from Ru(IV). Concerning the Ru(1.2) solid, the presence of Ru(IV) was detected by means of TPR experiments, in agreement with the high proportion of Ru(IV) on the surface. Therefore, a fraction of Ru loading was present in this solid as species with weaker metal-support interaction leading to the slight deactivation of this catalyst in the membrane reactor. (author)

  11. Non-Fermi-liquid behaviour in La4Ru6O19.

    Science.gov (United States)

    Khalifah, P; Nelson, K D; Jin, R; Mao, Z Q; Liu, Y; Huang, Q; Gao, X P; Ramirez, A P; Cava, R J

    2001-06-07

    Understanding the complexities of electronic and magnetic ground states in solids is one of the main goals of solid-state physics. Transition-metal oxides have proved to be particularly fruitful in this regard, especially for those materials with the perovskite structure, where the special characteristics of transition-metal-oxygen orbital hybridization determine their properties. Ruthenates have recently emerged as an important family of perovskites because of the unexpected evolution from high-temperature ferromagnetism in SrRuO3 to low-temperature superconductivity in Sr2RuO4 (refs 1, 2). Here we show that a ruthenate in a different structural family, La4Ru6O19, displays a number of highly unusual properties, most notably non-Fermi-liquid behaviour. The properties of La4Ru6O19 have no analogy among the thousands of previously characterized transition-metal oxides. Instead, they resemble those of CeCu6-xAux-a widely studied f-electron-based heavy fermion intermetallic compound that is often considered as providing the best example of non-Fermi-liquid behaviour. In the ruthenate, non-Fermi-liquid behaviour appears to arise from just the right balance between the interactions of localized electronic states derived from Ru-Ru bonding and delocalized states derived from Ru-O hybridization.

  12. Topology and electronic structure of flexible (Nb,Ru)O2 thermoelectrics.

    Science.gov (United States)

    Music, Denis; Schnabel, Volker; Bednarcik, Jozef

    2017-03-01

    Using combinatorial reactive sputtering, we have synthesised Nb-Ru-O thin films on Kapton (polyimide) with the Ru/Nb ratio from 0.5 to 1.1 in a dioxide type of environment. Based on correlative analysis, including synchrotron diffraction experiments and density functional theory, the topology of these amorphous samples is characterised by short metal-oxygen bonds and very pronounced metal-metal interactions within the second coordination shell. We suggest that the role of Nb is within bond length reduction and promotion of quantum confinement, giving rise to an increase in the Seebeck coefficient. Furthermore, these Nb-Ru-O thin films are mechanically flexible as there are no crack formation and delamination upon bending or rolling. This may be rationalised as follows. Nb-Ru-O appears ductile due to low topological connectivity and forms strong bonds with Kapton.

  13. Topology and electronic structure of flexible (Nb,Ru)O2 thermoelectrics

    Science.gov (United States)

    Music, Denis; Schnabel, Volker; Bednarcik, Jozef

    2017-03-01

    Using combinatorial reactive sputtering, we have synthesised Nb-Ru-O thin films on Kapton (polyimide) with the Ru/Nb ratio from 0.5 to 1.1 in a dioxide type of environment. Based on correlative analysis, including synchrotron diffraction experiments and density functional theory, the topology of these amorphous samples is characterised by short metal-oxygen bonds and very pronounced metal-metal interactions within the second coordination shell. We suggest that the role of Nb is within bond length reduction and promotion of quantum confinement, giving rise to an increase in the Seebeck coefficient. Furthermore, these Nb-Ru-O thin films are mechanically flexible as there are no crack formation and delamination upon bending or rolling. This may be rationalised as follows. Nb-Ru-O appears ductile due to low topological connectivity and forms strong bonds with Kapton.

  14. Conversion of biomass-derived sorbitol to glycols over carbon-materials supported Ru-based catalysts

    Science.gov (United States)

    Guo, Xingcui; Guan, Jing; Li, Bin; Wang, Xicheng; Mu, Xindong; Liu, Huizhou

    2015-11-01

    Ruthenium (Ru) supported on activated carbon (AC) and carbon nanotubes (CNTs) was carried out in the hydrogenolysis of sorbitol to ethylene glycol (EG) and 1,2-propanediol (1,2-PD) under the promotion of tungsten (WOx) species and different bases. Their catalytic activities and glycols selectivities strongly depended on the support properties and location of Ru on CNTs, owning to the altered metal-support interactions and electronic state of ruthenium. Ru located outside of the tubes showed excellent catalytic performance than those encapsulated inside the nanotubes. Additionally, the introduction of WOx into Ru/CNTs significantly improved the hydrogenolysis activities, and a complete conversion of sorbitol with up to 60.2% 1,2-PD and EG yields was obtained on RuWOx/CNTs catalyst upon addition of Ca(OH)2. Stability study showed that this catalyst was highly stable against leaching and poisoning and could be recycled several times.

  15. Formation of graphene on Ru(0001) surface

    Institute of Scientific and Technical Information of China (English)

    Pan Yi; Shi Dong-Xia; Gao Hong-Jun

    2007-01-01

    We report on the formation of a graphene monolayer on a Ru(0001) surface by annealing the Ru(0001) crystal.The samples are characterized by scanning tunnelling microscopy (STM) and Auger electron spectroscopy (AES). STM images show that the Moiré pattern is caused by the graphene layer mismatched with the underlying Ru(0001) surface and has an N × N superlattice. It is further found that the graphene monolayer on a Ru(0001) surface is very stable at high temperatures. Our results provide a simple and convenient method to produce a graphene monolayer on the Ru(0001) surface, which is used as a template for fabricating functional nanostructures needed in future nano devices and catalysis.

  16. Preparation of highly dispersed Ru-Sn bimetallic supported catalysts from the single source precursors Cp(PPh32Ru-SnX3 (X = Cl or Br

    Directory of Open Access Journals (Sweden)

    Ana Cláudia Bernardes Silva

    2003-06-01

    Full Text Available In this work highly dispersed Ru-Sn bimetallic catalysts have been prepared from organobimetallic Cp(PPh32Ru-SnX3 (X = Cl or Br complexes. These single source precursors can be easily impregnated in high surface area supports, such as activated carbon and sol-gel SiO2, and upon controlled thermal treatment the ligands are released as volatile products resulting in the formation of the bimetallic system Ru-Sn. Catalytic reactions, such as hydrodechlorination of CCl4 and chlorobenzene and TPR (Temperature Programmed Reduction experiments carried out with these RuSn catalysts suggested a strong interaction between Ruthenium and Tin. Mössbauer measurements showed that these materials when exposed to air are immediately oxidized to form Sn (IV. It was shown that upon controlled reduction conditions with H2 it is possible to reduce selectively Sn to different oxidation states and different phases. The Sn oxidation state showed significant effect on the catalytic hydrogenation of 1,5-cyclooctadiene. The use of these single source precursors with a controlled decomposition/reduction procedure allows the preparation of unique catalysts with an intimate interaction between the components ruthenium and tin and the possibility of varying the Sn oxidation state around the Ru metal.

  17. CO selective methanation in hydrogen-rich gas mixtures over carbon nanotube supported Ru-based catalysts

    Institute of Scientific and Technical Information of China (English)

    Jun Xiong; Xinfa Dong; Lingling Li

    2012-01-01

    Series of carbon nanotube supported Ru-based catalysts were prepared by impregnation method and applied successfully for complete removal of CO by CO selective methanation from H2-rich gas stream conducted in a fixed-bed quartz tubular reactor at ambient pressure.It was found that the metal promoter,reduction temperature and metal loading affected the catalytic properties significantly.The most excellent performance was presented by 30 wt% Ru-Zr/CNTs catalyst reduced at 350 ℃.Since it decreased CO concentration to below 10 ppm from 12000 ppm by CO selective methanation at the temperature range of 180-240 ℃,and kept CO selectivity higher than 85% at the temperature below 200 ℃.Characterization using XRD,TEM,H2-TPR and XPS suggests that Zr modification of Ru/CNTs results in the weakening of the interaction between Ru and CNTs,a higher Ru dispersion and the oxidization of surface Ru.Amorphous and high dispersed Ru particles with small size were obtained for 30 wt% Ru-Zr/CNTs catalyst reduced at 350 ℃,leading to excellent catalytic performance in CO selective methanation.

  18. Scanning tunnelling microscope studies of growth of RuO2(110) thin layer on Ru(0001)

    Institute of Scientific and Technical Information of China (English)

    Zhang Han-Jie; Lü Bin; Lu Yun-Hao; Huang Han; Li Hai-Yang; Bao Shi-Ning; He Pei-Mo

    2006-01-01

    This paper reports that the growth of RuO2(110) thin layer growth on Ru(0001) has been investigated by means of scanning tunnelling microscope (STM). The STM images showed a domain structure with three rotational domains of RuO2(110) rotated by an angle of 120°. The as-grown RuO2(110) thin layer is expanded from the bulk-truncated RuCO2(110) due to the large mismatch between RuCO2(110) and the Ru(0001) substrate. The results also indicate that growth of RuO2(110) thin layer on the Ru(0001) substrate by oxidation tends first to formation of the Ru-O (oxygen) chains in the [001] direction of RuO2(110).

  19. Thermodynamic assessment of the Al-Ru system

    CSIR Research Space (South Africa)

    Prins, SN

    2003-03-01

    Full Text Available describes the order disorder transformation with one Gibbs energy function. The RuAl6 phase was described as a stoichiometric phase and the remaining intermetallic phases (Ru4Al13, RuAl2 and Ru2Al3) were modelled with the sublattice model. The solubility...

  20. Metal- and ligand-assisted CO2 insertion into Ru-C, Ru-N, and Ru-O bonds of ruthenium(II) phosphine complexes: a density functional theory study.

    Science.gov (United States)

    Vadivelu, Prabha; Suresh, Cherumuttathu H

    2015-01-20

    The CO2 insertion reactions of [L4Ru(η(2)-CH2C6H4)] (1), [L4Ru(η(2)-OC6H3Me)] (2), and [L4Ru(η(2)-NHC6H4)] (3), where L = PH3 and PMe3, are modeled using density functional theory methods. In 1 and 2, the metal-assisted CO2 insertion occurs because of the favorable initial axial phosphine dissociation mechanism, whereas in 3, the ligand (NHC6H4)-assisted mechanism operates (ΔG(⧧) = +19.0 kcal/mol), wherein the nucleophilic affinity of the -NHC6H4 moiety aids the CO2 insertion process. The modeled mechanisms are consistent with the experimental findings by Hartwig et al. (J. Am. Chem. Soc, 1991, 113, 6499), in which the rate of the reactions of 1 and 2 depends on the added phosphine concentration, whereas the rate of the reaction of 3 is independent of the added phosphine concentration. In 1 and 2, CO2 is preferably inserted into the Ru-Caryl bond rather than the competitive Ru-CH2 and Ru-O bonds, respectively. In 1, the π-type orbital interaction of the aryl ring with the metal center is found to stabilize the transition state for Ru-Caryl bond insertion (ΔG(⧧) = +25.7 kcal/mol). In 2, the Ru-Caryl insertion (ΔG(⧧) = +23.0 kcal/mol) is thermodynamically preferred, while the kinetically preferred Ru-O bond insertion (ΔG(⧧) = +17.4 kcal/mol) is highly reversible. The more electron-donating and sterically bulky PMe3 facilitates the CO2 insertion of 1 and 2 because the initial dissociation of axial PMe3 is easier than that of PH3 by ca. +11.0 kcal/mol, whereas in the case of 3, the effect of PMe3 slightly increases the ΔG(⧧) value of 3. The increase in the nucleophilic affinity of amido nitrogen in 3 and the increase in the polarity of the solvent decrease the ΔG(⧧) value of 3 by 48%. The inclusion of the chelating dimethylphosphinoethane ligand in 3 along with the electron-donating substituent at the -NHC6H4 moiety and the polar solvent further reduces the ΔG(⧧) value of 3 by 62%, which demonstrates the role of the chelating ligand, electron

  1. Selective oxidation of methylamine over zirconia supported Pt-Ru, Pt and Ru catalysts

    Institute of Scientific and Technical Information of China (English)

    Aiying Song; Gongxuan Lu

    2015-01-01

    Pt–Ru, Pt and Ru catalysts supported on zirconia were prepared by impregnation method and were tested in se-lective oxidation of methylamine (MA) in aqueous media. Among three catalysts, Ru/ZrO2 was more active than Pt/ZrO2 while Pt–Ru/ZrO2 demonstrated the best catalytic activity due to the fact that Pt addition efficiently pro-moted the dispersion of active species in bimetallic catalyst. Therefore, the~100%TOC conversion and N2 selec-tivity were achieved over Pt–Ru/ZrO2, Pt/ZrO2 and Ru/ZrO2 catalysts at 190, 220 and 250 °C, respectively.

  2. Moessbauer Studies of Dilute {sup 119}Sn and {sup 57}Fe in SrRuO{sub 3} and Sr{sub 2}FeRuO{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Nowik, I.; Felner, I. [Hebrew University, Racah Institute of Physics (Israel)

    2004-12-15

    In both compounds the {sup 57}Fe{sup 3+} reveals no magnetic hyperfine structure at 90 K, yet large hyperfine fields at 4.2 K. {sup 119}Sn{sup 4+} in SrRuO{sub 3} reveals hyperfine fields starting from T{sub c}=165 K. In Sr{sub 2}Fe{sup 3+}Ru{sup 5+}O{sub 6} the iron and tin exhibit at 4.2 K wide distributions of hyperfine interactions, typical to Fe/Ru disorder and spin glass structure.

  3. Modeling the electro-oxidation of CO and H2/CO on Pt, Ru, PtRu and Pt3Sn

    DEFF Research Database (Denmark)

    Liu, Ping; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2003-01-01

    is developed to describe the electro-oxidation of CO and H-2 at conditions relevant to the anode of a PEM fuel cell. The model is very simple and allows us to express the kinetics of a promoted anode surface relative to the activity of pure Pt directly from the calculated adsorption energy differences...... geometry is the same. This ligand effect is ascribed to changes in the electronic structure of the surface atoms due to interactions with the surroundings, and the physical origin of the effect is discussed. The calculated adsorption energetics is used as input into a simple kinetic model, which....... In agreement with experiments, the model shows Ru, PtRu and Pt3Sn to start oxidizing CO at lower potentials than Pt. In addition, the model shows PtRu to have a considerably lower overpotential for H-2 oxidation in the presence of CO than Pt. Pt3Sn is even better than PtRu, while Ru is found to be considerably...

  4. Nanoscale decomposition of Nb-Ru-O

    Science.gov (United States)

    Music, Denis; Geyer, Richard W.; Chen, Yen-Ting

    2016-11-01

    A correlative theoretical and experimental methodology has been employed to explore the decomposition of amorphous Nb-Ru-O at elevated temperatures. Density functional theory based molecular dynamics simulations reveal that amorphous Nb-Ru-O is structurally modified within 10 ps at 800 K giving rise to an increase in the planar metal - oxygen and metal - metal population and hence formation of large clusters, which signifies atomic segregation. The driving force for this atomic segregation process is 0.5 eV/atom. This is validated by diffraction experiments and transmission electron microscopy of sputter-synthesized Nb-Ru-O thin films. Room temperature samples are amorphous, while at 800 K nanoscale rutile RuO2 grains, self-organized in an amorphous Nb-O matrix, are observed, which is consistent with our theoretical predictions. This amorphous/crystalline interplay may be of importance for next generation of thermoelectric devices.

  5. PHARMACOKINETICS OF RU486 IN RABBITS

    Institute of Scientific and Technical Information of China (English)

    ZHANGMing-Hua; CHUYun-Hong; LIQui; CHANGLi-Min; FANGZhen; JINGZuao-Ying

    1989-01-01

    Intravaginal release of contraceptive steroid by avoiding the first-pass effect may provide a suitable route of administration, thus leading to higher bioavailabilities. RU486 is significantly metabolizlcd by the first-pass metabolism. We have studied its pharmacokinetics

  6. Helium, neon and argon diffraction from Ru(0001).

    Science.gov (United States)

    Minniti, M; Díaz, C; Fernández Cuñado, J L; Politano, A; Maccariello, D; Martín, F; Farías, D; Miranda, R

    2012-09-05

    We present an experimental and theoretical study of He, Ne and Ar diffraction from the Ru(0001) surface. Close-coupling calculations were performed to estimate the corrugation function and the potential well depth in the atom-surface interaction in all three cases. DFT (density functional theory) calculations, including van der Waals dispersion forces, were used to validate the close-coupling results and to further analyze the experimental results. Our DFT calculations indicate that, in the incident energy range 20-150 meV, anticorrugating effects are present in the case of He and Ar diffraction, whereas normal corrugation is observed with Ne beams.

  7. Reactivity of diaminogermylenes with ruthenium carbonyl: Ru3Ge3 and RuGe2 derivatives.

    Science.gov (United States)

    Cabeza, Javier A; García-Álvarez, Pablo; Polo, Diego

    2011-07-04

    The nature of the products of the reactions of [Ru(3)(CO)(12)] with diaminogermylenes depends upon the volume and the cyclic or acyclic structure of the latter. Thus, the triruthenium cluster [Ru(3){μ-Ge(NCH(2)CMe(3))(2)C(6)H(4)}(3)(CO)(9)], which has a planar Ru(3)Ge(3) core and an overall C(3h) symmetry, has been prepared in quantitative yield by treating [Ru(3)(CO)(12)] with an excess of the cyclic 1,3-bis(neo-pentyl)-2-germabenzimidazol-2-ylidene in toluene at 100 °C, but under analogous reaction conditions, the acyclic and bulkier Ge(HMDS)(2) (HMDS = N(SiMe(3))(2)) quantitatively leads to the mononuclear ruthenium(0) derivative [Ru{Ge(HMDS)(2)}(2)(CO)(3)]. Mixtures of products have been obtained from the reactions of [Ru(3)(CO)(12)] with the cyclic and very bulky 1,3-bis(tert-butyl)-2-germaimidazol-2-ylidene under various reaction conditions. The Ru(3)Ge(3) and RuGe(2) products reported in this paper are the first ruthenium complexes containing diaminogermylene ligands.

  8. Ru-NQR Study for Novel Phase Transition in CeRu2Al10

    Science.gov (United States)

    Matsumura, Masahiro; Tomita, Naoya; Matsuoka, Junichirou; Kishimoto, Yasuki; Kato, Harukazu; Kitagawa, Kentaro; Nishioka, Takashi; Tanida, Hiroshi; Sera, Masafumi

    2014-10-01

    We have performed Ru-NQR measurements on CeRu2Al10 exhibiting novel phase transition at an abnormally high temperature T0 = 27.3 K and on NdRu2Al10 with a magnetic transition temperature Tm = 2.4 K as a reference RKKY system. The splitting of the NQR line due to internal fields below T0 shows a mean-field-like monotonic increase, indicating no change in the magnetic structure below T0. The internal field strength is one order larger than those at Al sites in CeRu2Al10, and is comparable to that at the Ru site in NdRu2Al10 despite the sevenfold smaller magnitude of the 4f moment, being indicative of an enhanced conduction electron polarization at the Ru site. One of the causes of the high T0 might be the enhanced exchange coupling through the Ce-Ru-Ce path mediated by the enhanced conduction electron polarization. Being similar to that in the Al site, the nuclear spin-lattice relaxation rate 1/T1 shows a gap-like decrease below T0 without enhancement owing to a critical slowing down at T0, in contrast to the mean field 2nd-order transition.

  9. Metal-insulator transition in Ba3Fe1 -xRu2 +xO9 : Interplay between site disorder, chemical percolation, and electronic structure

    Science.gov (United States)

    Middey, S.; Aich, Payel; Meneghini, C.; Mukherjee, K.; Sampathkumaran, E. V.; Siruguri, V.; Mahadevan, P.; Ray, Sugata

    2016-11-01

    Perovskites containing barium metal at the A site often take up unusual hexagonal structures having more than one type of possible sites for the B cation to occupy. This opens up various different B -B - or B -O-B -type connectivities and consequent physical properties which are naturally missing in cubic perovskites. BaRuO3 is one such system where doping of Ru (4 d4 ) by other transition metals (Mn +) creates similar conditions, giving rise to various M -Ru interactions. Interestingly, the 6 H hexagonal structure of doped barium ruthenate triple perovskite (Ba3M Ru2O9 ) seems to possess some internal checks because within the structure M ion always occupies the 2 a site and Ru goes to the 4 f site, allowing only M -O-Ru 180∘ and Ru-O-Ru 90∘ interactions to occur. The only exception is observed in the case of the Fe dopant, which allows us to study almost the full Ba3Fe1 -xRu2 +xO9 series of compounds with wide ranges of x because here Fe ions have the ability to freely go to the 4 f sites and Ru readily takes up the 2 a positions. Therefore, here one has the opportunity to probe the evolution of electronic and magnetic properties as a function of doping by going from BaRuO3 (paramagnetic metal) to BaFeO3 (ferromagnetic insulator). Our detailed experimental and theoretical results show that the series does exhibit a percolative metal-insulator transition with an accompanying but not coincidental magnetic transition as a function of x .

  10. Ru(0) and Ru(II) nitrosyl pincer complexes: structure, reactivity, and catalytic activity.

    Science.gov (United States)

    Fogler, Eran; Iron, Mark A; Zhang, Jing; Ben-David, Yehoshoa; Diskin-Posner, Yael; Leitus, Gregory; Shimon, Linda J W; Milstein, David

    2013-10-07

    Despite considerable interest in ruthenium carbonyl pincer complexes and their substantial catalytic activity, there has been relatively little study of the isoelectronic ruthenium nitrosyl complexes. Here we describe the synthesis and reactivity of several complexes of this type as well as the catalytic activity of complex 6. Reaction of the PNP ligand (PNP = 2,6-bis((t)Bu2PCH2)pyridine) with RuCl3(NO)(PPh3)2 yielded the Ru(II) complex 3. Chloride displacement by BAr(F-) (BAr(F-) = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) gave the crystallographicaly characterized, linear NO Ru(II) complex 4, which upon treatment with NaBEt3H yielded the Ru(0) complexes 5. The crystallographically characterized Ru(0) square planar complex 5·BF4 bears a linear NO ligand located trans to the pyridilic nitrogen. Further treatment of 5·BF4 with excess LiOH gave the crystallographicaly characterized Ru(0) square planar, linear NO complex 6. Complex 6 catalyzes the dehydrogenative coupling of alcohols to esters, reaching full conversion under air or under argon. Reaction of the PNN ligand (PNN = 2-((t)Bu2PCH2)-6-(Et2NCH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave an equilibrium mixture of isomers 7a and 7b. Further treatment of 7a + 7b with 2 equivalent of sodium isopropoxide gave the crystallographicaly characterized, bent-nitrosyl, square pyramidal Ru(II) complex 8. Complex 8 was also synthesized by reaction of PNN with RuCl3(NO)(H2O)2 and Et3N in ethanol. Reaction of the "long arm" PN(2)N ligand (PN(2)N = 2-((t)Bu2PCH2-)-6-(Et2NCH2CH2)pyridine) with RuCl3(NO)(H2O)2 in ethanol gave complex 9, which upon treatment with 2 equiv of sodium isopropoxide gave complex 10. Complex 10 was also synthesized directly by reaction of PN(2)N with RuCl3(NO)(H2O)2 and a base in ethanol. A noteworthy aspect of these nitrosyl complexes is their preference for the Ru(0) oxidization state over Ru(II). This preference is observed with both aromatized and dearomatized pincer ligands, in

  11. Effects of BaRuO{sub 3} addition on hydrogen desorption in MgH{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Baricco, M., E-mail: marcello.baricco@unito.it [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P. Giuria 9, 10125 Torino (Italy); Rahman, M.W.; Livraghi, S.; Castellero, A. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P. Giuria 9, 10125 Torino (Italy); Enzo, S. [Dipartimento di Chimica, Universita di Sassari, Via Vienna, 2, 07100 Sassari (Italy); Giamello, E. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Via P. Giuria 9, 10125 Torino (Italy)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Interaction of BaRuO{sub 3} with hydrogen studied. Black-Right-Pointing-Pointer BaRuO{sub 3} is able to release hydrogen after absorption. Black-Right-Pointing-Pointer A distorted rhomohedral phase is formed in BaRuO{sub 3} after hydrogen absorption. Black-Right-Pointing-Pointer A mixture of BaRuO{sub 3} with MgH{sub 2} is able to desorb hydrogen much faster than the parent materials. The interaction of hydrogen with the oxide additive is a crucial aspect for improving the hydrogen desorption rate. - Abstract: Hydrogen storage in MgH{sub 2} is strongly limited by kinetic constraints, so that several additives have been considered in order to improve the rate of hydrogen desorption. The present work is devoted to investigate the effect of BaRuO{sub 3} addition on hydrogen absorption and desorption properties of MgH{sub 2}. BaRuO{sub 3} was prepared by solid-state synthesis of BaO and Ru in oxidizing environment. The interaction of as-prepared BaRuO{sub 3} with hydrogen at room temperature was examined by thermal desorption and X-ray diffraction experiments, showing that BaRuO{sub 3} has the ability to uptake hydrogen in the bulk. The hydrogen interaction is discussed with respect to octahedral ruthenium local environment present in the oxide structure. Addition of 1 mol.% BaRuO{sub 3} to MgH{sub 2} was performed by ball milling. Hydrogen desorption properties were investigated by Sievert and DSC, connected with a H{sub 2} detector. The H{sub 2} desorbed from of the nano-structured materials is lower than the theoretical content in MgH{sub 2}, due to the presence of a non-reactive MgO layer. A remarkable increase of the H{sub 2} desorption kinetics in nano-structured MgH{sub 2} was observed with respect to bare MgH{sub 2}. The activation energy for hydrogen desorption from MgH{sub 2}/BaRuO{sub 3} mixture was estimated by Arrhenius and Kissinger methods and a value around 130 kJ mol{sup -1} and 90 kJ mol{sup -1} was obtained

  12. Carbon supported nanoparticles Pt Ru (Pt Ru/C electrocatalysts) prepared using electron beam irradiation; Preparacao de nanoparticulas de PtRu suportadas em carbono (eletrocatalisadores PtRu/C) utilizando feixe de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F. da; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Programa de Celulas a Combustivel], e-mail: espinace@ipen.br, e-mail: dfsilva@ipen.br

    2006-07-01

    Carbon-supported Pt Ru (electrocatalysts PtRu/C nanoparticles) were prepared submitting a water/ethylene glycol mixture containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The PtRu/C electrocatalysts were characterized by EDX, XRD and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C ETEK electrocatalyst at ambient temperature. (author)

  13. Carbon supported nanoparticles Pt Ru (Pt Ru/C electrocatalysts) prepared using electron beam irradiation; Preparacao de nanoparticulas de PtRu suportadas em carbono (eletrocatalisadores PtRu/C) utilizando feixe de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F. da; Oliveira Neto, Almir; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Programa de Celulas a Combustivel], e-mail: espinace@ipen.br, e-mail: dfsilva@ipen.br

    2006-07-01

    Carbon-supported Pt Ru (electrocatalysts PtRu/C nanoparticles) were prepared submitting a water/ethylene glycol mixture containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The PtRu/C electrocatalysts were characterized by EDX, XRD and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C ETEK electrocatalyst at ambient temperature. (author)

  14. Fundamental studies of hydrogen interaction with supported meta and bimetallic catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, S.

    1993-12-07

    The thesis is divided into 3 parts: interaction of H with silica supported Ru catalysts (high pressure in situ NMR), in situ NMR study of H interaction with supported Ru-group IB bimetallic catalysts, and in-situ NMR study of H effects on silica-supported Pt, Rh and Ru catalysts.

  15. Graphene substrate-mediated catalytic performance enhancement of Ru nanoparticles: A first-principles study

    KAUST Repository

    Liu, Xin

    2012-01-01

    The structural, energetic and magnetic properties of Ru nanoparticles deposited on pristine and defective graphene have been thoroughly studied by first-principles based calculations. The calculated binding energy of a Ru 13 nanoparticle on a single vacancy graphene is as high as -7.41 eV, owing to the hybridization between the dsp states of the Ru particles with the sp 2 dangling bonds at the defect sites. Doping the defective graphene with boron would further increase the binding energy to -7.52 eV. The strong interaction results in the averaged d-band center of the deposited Ru nanoparticle being upshifted toward the Fermi level from -1.41 eV to -1.10 eV. Further study reveals that the performance of the nanocomposites against hydrogen, oxygen and carbon monoxide adsorption is correlated to the shift of the d-band center of the nanoparticle. Thus, Ru nanoparticles deposited on defective graphene are expected to exhibit both high stability against sintering and superior catalytic performance in hydrogenation, oxygen reduction reaction and hydrogen evolution reaction. © 2012 The Royal Society of Chemistry.

  16. Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3 Nanosheets.

    Science.gov (United States)

    Weber, Daniel; Schoop, Leslie M; Duppel, Viola; Lippmann, Judith M; Nuss, Jürgen; Lotsch, Bettina V

    2016-06-01

    Spin 1/2 honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still in demand. Here, we report the exfoliation of the magnetic semiconductor α-RuCl3 into the first halide monolayers and the magnetic characterization of the spin 1/2 honeycomb arrangement of turbostratically stacked RuCl3 monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin 1/2 state by electron injection into the layers. The restacked, macroscopic pellets of RuCl3 layers lack symmetry along the stacking direction. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at TN = 7 K if the field is aligned parallel to the ab-plane, while the magnetic properties differ from bulk α-RuCl3 if the field is aligned perpendicular to the ab-plane. The deliberate introduction of turbostratic disorder to manipulate the magnetic properties of RuCl3 is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model.

  17. Simulating Ru L 3 -Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  18. Description of mixed symmetry states in 96Ru using IBM-2

    Science.gov (United States)

    Zhang, DaLi; Mu, ChengFu

    2017-04-01

    We have investigated the properties of low-lying states in 96Ru within the framework of the neutron-proton interacting boson model (IBM-2), with special attention paid to the characteristics of the mixed symmetry states. By considering the relative energy of d proton boson to be different from that of neutron boson, the level energies and M1, E2 transition strengths have been calculated. The IBM-2 calculation is consistent with the experimental data of 96Ru both quantitatively and qualitatively. Particularly, the strong M1 transition between the 42 + and 41 + states has been reproduced nicely. The calculated results show that the M1 transition strength of B( M1; 42 + → 41 +) in 96Ru can be described successfully by the IBM-2.

  19. Description of mixed symmetry states in 96Ru using IBM-2

    Science.gov (United States)

    Zhang, DaLi; Mu, ChengFu

    2017-04-01

    We have investigated the properties of low-lying states in 96Ru within the framework of the neutron-proton interacting boson model (IBM-2), with special attention paid to the characteristics of the mixed symmetry states. By considering the relative energy of d proton boson to be different from that of neutron boson, the level energies and M1, E2 transition strengths have been calculated. The IBM-2 calculation is consistent with the experimental data of 96Ru both quantitatively and qualitatively. Particularly, the strong M1 transition between the 42 + and 41 + states has been reproduced nicely. The calculated results show that the M1 transition strength of B( M1; 42 + → 41 +) in 96Ru can be described successfully by the IBM-2.

  20. Investigation of superhalogen behaviour of RuF ( = 1–7) clusters: density functional theory (DFT) study

    Indian Academy of Sciences (India)

    Shamoon Ahmad Siddiqui; Tabish Rasheed; Nadir Bouarissa

    2013-08-01

    In the present investigation, interaction of ruthenium (Ru) atoms with fluorine (F) atoms was studied using the density functional theory utilizing B3LYP method. It was found that up to seven F atoms can bind to a single Ru atom which results in increase of electron affinities successively, reaching a peak value of 6.95 eV for RuF6. Its stability and reactivity were also examined by using HOMO–LUMO gap, molecular orbital analysis and binding energy of these clusters. It is found that energy required for dissociation of F2 molecules are higher than energy required for dissociation of F atoms. The unusual properties are attributed to the involvement of inner shell 4-electrons, which not only allow RuF clusters to belong to the class of superhalogens but also show that its valence can exceed the nominal value of 1. The interaction of RuF4 superhalogen with an alkali atom lithium (Li) were also studied which suggests that a new class of salt can be synthesized by reacting RuF4 with Li.

  1. Electronic Structure of the Kitaev Material α-RuCl3 Probed by Photoemission and Inverse Photoemission Spectroscopies.

    Science.gov (United States)

    Sinn, Soobin; Kim, Choong Hyun; Kim, Beom Hyun; Lee, Kyung Dong; Won, Choong Jae; Oh, Ji Seop; Han, Moonsup; Chang, Young Jun; Hur, Namjung; Sato, Hitoshi; Park, Byeong-Gyu; Kim, Changyoung; Kim, Hyeong-Do; Noh, Tae Won

    2016-12-21

    Recently, α-RuCl3 has attracted much attention as a possible material to realize the honeycomb Kitaev model of a quantum-spin-liquid state. Although the magnetic properties of α-RuCl3 have been extensively studied, its electronic structure, which is strongly related to its Kitaev physics, is poorly understood. Here, the electronic structure of α-RuCl3 was investigated by photoemission (PE) and inverse-photoemission (IPE) spectroscopies. The band gap was directly measured from the PE and IPE spectra and was found to be 1.9 eV, much larger than previously estimated values. Local density approximation (LDA) calculations showed that the on-site Coulomb interaction U could open the band gap without spin-orbit coupling (SOC). However, the SOC should also be incorporated to reproduce the proper gap size, indicating that the interplay between U and SOC plays an essential role. Several features of the PE and IPE spectra could not be explained by the results of LDA calculations. To explain such discrepancies, we performed configuration-interaction calculations for a RuCl6(3-) cluster. The experimental data and calculations demonstrated that the 4d compound α-RuCl3 is a Jeff = 1/2 Mott insulator rather than a quasimolecular-orbital insulator. Our study also provides important physical parameters required for verifying the proposed Kitaev physics in α-RuCl3.

  2. Shape transitions in neutron-rich Ru isotopes: spectroscopy of 109,110,111,112Ru

    Energy Technology Data Exchange (ETDEWEB)

    Hua, H; Cline, D; Hayes, A B; Teng, R; Riley, D; Clark, R M; Fallon, P; Goergen, A; Macchiavelli, A O; Vetter, K

    2005-06-29

    The spectroscopy of neutron-rich {sup 109,110,111,112}Ru nuclei was studied by measuring the prompt {gamma} rays originated from fission fragments, produced by the {sup 238}U({alpha},f) fusion-fission reaction, in coincidence with the detection of both fragments. For {sup 109,111}Ru, both the negative-parity (h{sub 11/2} orbitals) and positive-parity (g{sub 7/2} and/or d{sub 5/2} orbitals) bands were extended to substantially higher spin and excitation energy than known previously. The ground-state and {gamma}-vibrational bands of {sup 110,112}Ru also were extended to higher spin, allowing observation of the second band crossing at the rotational frequency of {approx}450 keV in {sup 112}Ru, which is {approx}50 keV above the first band crossing. At a similar rotational frequency, the first band crossing for the h{sub 11/2} band in {sup 111}Ru was observed, which is absent in {sup 109}Ru. These band crossings most likely are caused by the alignment of the g{sub 9/2} proton pair. This early onset of the band crossing for the aligned {pi}g{sub 9/2} orbitals may be evidence of a triaxial shape transition from prolate to oblate occurring in {sup 111}Ru. The data together with a comparison of cranked shell model predictions are presented.

  3. The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing.

    Science.gov (United States)

    Luo, Jiaojiao; Zhou, Cuisong; Shi, Yalin; Zhang, Lei; Xiao, Dan

    2013-10-21

    Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.

  4. Ru-indoloquinoline complex as a selective and effective human telomeric G-quadruplex binder

    Science.gov (United States)

    Yu, Hui-juan; Zhao, Ying; Mo, Wei-jie; Hao, Zhi-feng; Yu, Lin

    2014-11-01

    Indoloquinoline and its derivatives have been reported to be a kind of efficient G-quadruplex binder and have been found to interact preferentially to intramolecular G-quadruplex and inhibit telomerase activity in human K562 cells and SW620 cells. In contrast to indoloquinoline derivatives, much less is known about the metal complex based on indoloquinoline or its derivative. In this report, we studied the interaction of ruthenium complex [Ru(bpy)2(itatp)]2+ containing indoloquinoline moiety with human telomeric G-quadruplex DNA (Telo22) and c-myc G-quadruplex DNA (Pu27) by UV-visible (UV-Vis), fluorescence spectroscopy, fluorescent intercalator displacement (FID), thermal denaturation studies and CD spectroscopy. The results suggest that [Ru(bpy)2(itatp)]2+ displays a strong π-π stacking interaction with human telomeric G-quadruplex with a high binding constant (∼107 M-1), but just exhibits moderate binding affinity to c-myc G-quadruplex, thus showing significant selectivity to human telomeric G-quadruplex. The CD titration results indicate that [Ru(bpy)2(itatp)]2+ could effectively convert Telo22 into antiparallel G-quadruplex conformation, while in the c-myc G-quadruplex case, instead of promoting Pu27 to fold into G-quadruplex, [Ru(bpy)2(itatp)]2+ destroys the parallel G-quadruplex structure of Pu27.

  5. Interaction of the carbon monoxide-releasing molecule Ru(CO)3Cl(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of carbon monoxide binding by integrating cavity dual-beam spectrophotometry.

    Science.gov (United States)

    Rana, Namrata; McLean, Samantha; Mann, Brian E; Poole, Robert K

    2014-12-01

    Carbon monoxide (CO) is a toxic gas that binds to haems, but also plays critical signalling and cytoprotective roles in mammalian systems; despite problems associated with systemic delivery by inhalation of the gas, it may be employed therapeutically. CO delivered to cells and tissues by CO-releasing molecules (CO-RMs) has beneficial and toxic effects not mimicked by CO gas; CO-RMs are also attractive candidates as novel antimicrobial agents. Salmonella enterica serovar Typhimurium is an enteropathogen causing gastroenteritis in humans. Recent studies have implicated haem oxygenase-1 (HO-1), the protein that catalyses the degradation of haem into biliverdin, free iron and CO, in the host immune response to Salmonella infection. In several studies, CO administration via CO-RMs elicited many of the protective roles of HO-1 induction and so we investigated the effects of a well-characterized water-soluble CO-RM, Ru(CO)3Cl(glycinate) (CORM-3), on Salmonella. CORM-3 exhibits toxic effects at concentrations significantly lower than those reported to cause toxicity to RAW 264.7 macrophages. We demonstrated here, through oxyhaemoglobin assays, that CORM-3 did not release CO spontaneously in phosphate buffer, buffered minimal medium or very rich medium. CORM-3 was, however, accumulated to high levels intracellularly (as shown by inductively coupled plasma MS) and released CO inside cells. Using growing Salmonella cultures without prior concentration, we showed for the first time that sensitive dual-beam integrating cavity absorption spectrophotometry can detect directly the CO released from CORM-3 binding in real-time to haems of the bacterial electron transport chain. The toxic effects of CO-RMs suggested potential applications as adjuvants to antibiotics in antimicrobial therapy.

  6. A new Kaempferol-based Ru(II) coordination complex, Ru(kaem)Cl(DMSO){sub 3}: Structure and absorption-emission spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Shao, Ming Wei; Gang, Jong Back; Kim, Sang Ho; Yoon, Min Young [Gachon University, Sungnam (Korea, Republic of)

    2016-10-15

    Recent interest in developing a new anticancer drug with low side effects has led to the study of the combination of two new anticancer drugs. Although both kaempferol (kaem) and Ru-based metal complexes have not been proven as effective drugs, their unique anticancer activities with reduced side effects have drawn our attention to the need for further studies on their potential in anticancer application. Herein, we report the synthesis, characterization, structure, and spectroscopic properties of a kaem-based Ru (II) complex, RuCl(kaem)(DMSO){sub 3} (1). Because of the presence of a catechol-like functional group in its dihydropyran ring, kaem can strongly bind to the Ru(II) metal center in a basic medium. The molecular structure of the complex was characterized by spectroscopic studies and X-ray crystal structure analysis. In addition, the complex forms a molecular dimer as a result of the cooperative effect of H-bonding and π–π stacking interactions. Moreover, the molecular dimer forms a ladder-like one-dimensional network structure by water mediated H-bonding that further extended into a three-dimensional packing structure. UV–Vis spectroscopy studies of the complex demonstrated the appearance of a strong metal to ligand charge transfer (MLCT) band in the visible region with strong fluorescence emission derived from the MLCT. Further studies are now in progress to demonstrate synergetic anticancer activity.

  7. Temperature-induced transformation of electrochemically formed hydrous RuO2 layers over Ru(0001) model electrodes

    Science.gov (United States)

    Krause, Philipp P. T.; Camuka, Hava; Leichtweiss, Thomas; Over, Herbert

    2016-07-01

    Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001).Hydrous RuO2 reveals excellent performance both as a supercapacitor and as a heterogeneous oxidation catalyst. Molecular understanding of these processes needs, however, a model system with preferably low structural and morphological complexity. This goal is partly accomplished here by using single crystalline Ru(0001) as a template on which hydrous RuO2 is electrochemically formed. The hydrous RuO2 layers on Ru(0001) and their temperature induced transformation under ultra high vacuum (UHV) conditions are comprehensively characterized by scanning electron microscopy and X-ray photoemission spectroscopy. The hydrous RuO2 layer grows with an intricate morphology governed by the presence of step bunching regions of the Ru(0001) surface. Upon annealing to 200 °C in UHV the hydrous RuO2 layer transforms mostly into flat metallic Ru islands and occasionally into (100) and (111) oriented RuO2 particles aligned along the high symmetry direction of Ru(0001). Electronic supplementary information (ESI) available. See DOI: 10

  8. A general route for RuO2 deposition on metal oxides from RuO4

    DEFF Research Database (Denmark)

    Kleiman-Shwarsctein, Alan; Laursen, Anders Bo; Cavalca, Filippo;

    2012-01-01

    A novel method for the deposition of RuO2 from RuO4(g) on diverse metal oxides has been developed by grafting dopamine onto the otherwise un-reactive metal oxide surface. Oxygen evolution reaction on TiO2 and the photoelectrochemical improvement of WO3 by deposition of RuO2 are just a few examples...

  9. Magnetic behavior of metallic kagome lattices, Tb3Ru4Al12 and Er3Ru4Al12

    Science.gov (United States)

    Upadhyay, Sanjay Kumar; Iyer, Kartik K.; Sampathkumaran, E. V.

    2017-08-01

    We report the magnetic behavior of two intermetallic-based kagome lattices, Tb3Ru4Al12 and Er3Ru4Al12, crystallizing in the Gd3Ru4Al2-type hexagonal crystal structure, by measurements in the range 1.8-300 K with bulk experimental techniques (ac and dc magnetization, heat capacity, and magnetoresistance). The main finding is that the Tb compound, known to order antiferromagnetically below (T N =) 22 K, shows glassy characteristics at lower temperatures (\\ll 15 K), thus characterizing this compound as a re-entrant spin-glass. The data reveal that the glassy phase is quite complex and is of a cluster type. Since glassy behavior was not seen for the Gd analog in the past literature, this finding on the Tb compound emphasizes that this kagome family could provide an opportunity to explore the role of higher-order interactions (such as quadrupole) in bringing out magnetic frustration. Additional findings reported here for this compound are: (i) The plots of temperature dependence of magnetic susceptibility and electrical resistivity data in the range 12-20 K, just below T N , are found to be hysteretic leading to a magnetic phase in this intermediate temperature range, mimicking disorder-broadened first-order magnetic phase transitions; (ii) features attributable to an interesting magnetic phase co-existence phenomenon in the isothermal magnetoresistance in zero field, after travelling across metamagnetic transition fields, are observed. With respect to the Er compound, we do not find any evidence for long-range magnetic ordering down to 2 K, but this compound appears to be on the verge of magnetic order at 2 K.

  10. Electrooxidation of CO on Ru(0001) and RuO2(100) Electrode Surfaces

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The electrooxidation of CO on Ru (0001) and RuO2 (100) electrode surfaces were characterized by cyclic voltammetry, AES and RHEED. The CO adlayer was first partially oxidized at 0.8 V, which is controlled by the attack of oxygen species toward the Ru(0001) surface. The remaining CO adlayer oxidation at 0.55 V is related to the combination of CO molecules with oxygen species already located on the surface. In contrast, successive peaks on RuO2(100) at 0.4 V and 0.72 V are observed, which shows that CO molecules can directly react with two different lattice-oxygen on the surface to carbon dioxide.

  11. High-Density Stacked Ru Nanocrystals for Nonvolatile Memory Application

    Institute of Scientific and Technical Information of China (English)

    MAO Ping; ZHANG Zhi-Gang; PAN Li-Yang; XU Jun; CHEN Pei-Yi

    2009-01-01

    @@ Stacked ruthenium (Ru) nanocrystals (NCs) are formed by rapid thermal annealing for the whole gate stacks and embedded in memory structure, which is compatible with conventional CMOS technology. Ru NCs with high density (3×1012 cm-2 ), small size (2-4 nm) and good uniformity both in aerial distribution and morphology are formed. Attributed to the higher surface trap density, a memory window of 5.2 V is obtained with stacked Ru NCs in comparison to that of 3.5 V with single-layer samples. The stacked Ru NCs device also exhibits much better retention performance because of Coulomb blockade and vertical uniformity between stacked Ru NCs.

  12. Carbon coated face-centered cubic Ru-C nanoalloys.

    Science.gov (United States)

    Zhao, Zhisheng; Meng, Chuanmin; Li, Peifang; Zhu, Wenjun; Wang, Qianqian; Ma, Yanming; Shen, Guoyin; Bai, Ligang; He, Hongliang; He, Duanwei; Yu, Dongli; He, Julong; Xu, Bo; Tian, Yongjun

    2014-09-07

    Carbon-encapsulated ruthenium-carbon (Ru-C) nanoalloys were synthesized by dynamic shocks. The Ru-C alloy shows a new fcc structure different from the original hcp structure of metal Ru. This fcc phase is assigned to a Ru32C4 solid solution with a lattice parameter of 3.868(2) Å and a bulk modulus KT0 of 272(12) GPa. The small amount of carbon in the solid solution enhances the thermodynamic and chemical stabilities with respect to pure Ru, as well as induces changes in the electronic properties, which have direct applications in improving the material's catalytic activity and selectivity.

  13. CO oxidation on fully oxygen covered Ru(0001)

    DEFF Research Database (Denmark)

    Sljivancanin, Zeljko; Hammer, Bjørk

    2010-01-01

    We present a reaction mechanism for CO oxidation at the Ru(0001)-(1×1) surface. By means of density-functional theory studies, we compare the reactivity of flat and stepped regions of the Ru(0001). We find that at saturation oxygen coverage, where the flat parts are unreactive toward CO adsorption...... an intricate reaction pathway for CO adsorption and CO2 formation exists at the monatomic Ru step. By suggesting an efficient mechanism for CO oxidation on nonoxidic Ru, our results offer an explanation for the controversy in the experimental literature regarding how nonoxidic Ru may be as active in CO...

  14. Pt Ru/C electrocatalysts prepared using electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio Furtunato da; Oliveira Neto, Almir; Pino, Eddy Segura; Brandalise, Michele; Linardi, Marcelo; Spinace, Estevam Vitorio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mail: espinace@ipen.br

    2007-10-15

    Pt Ru/C electrocatalysts (carbon-supported Pt Ru nanoparticles) were prepared submitting water/ethylene glycol mixtures containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The electrocatalysts were characterized by energy dispersive X ray analysis (EDX), X ray diffraction (XRD) and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained Pt Ru/C electrocatalysts showed superior performance for methanol electro-oxidation at room temperature compared to commercial Pt Ru/C electrocatalyst. (author)

  15. Valence modulations in CeRuSn

    NARCIS (Netherlands)

    Feyerherm, R.; Dudzik, E.; Prokeš, K.; Mydosh, J.A.; Huang, Y.K.; Pöttgen, R.

    2014-01-01

    CeRuSn exhibits an extraordinary room temperature structure at 300 K with the coexistence of two types of Ce ions, namely trivalent Ce3+ and intermediate-valent Ce(4−δ)+, in a metallic environment. The ordered arrangement of these two Ce types on specific crystallographic sites results in a doubling

  16. Electroreflectance study of RuSe 2

    Science.gov (United States)

    Huang, Y. S.; Lin, S. S.; Sheu, J. S.; Shen, W. M.; Pollak, Fred H.

    1990-12-01

    We report the first electrolyte-electroreflectance (EER) study of a RuSe 2 single crystal in the photon energy region of 0.9-5.5 eV. The EER spectrum exhibits differential like structure in the vicinity of interband transitions. The transition energies are determined accurately. A probable energy-band structure is constructed.

  17. A study of thermodynamic properties of dilute Fe-Ru alloys by 57Fe Mössbauer spectroscopy

    Science.gov (United States)

    Idczak, R.; Konieczny, R.; Chojcan, J.

    2016-12-01

    The room temperature Mössbauer spectra of 57Fe were measured for Fe1- x Ru x solid solutions with x in the range 0.01 ≤ x ≤ 0.08. The obtained data were analysed in terms of short-range order parameter (SRO) and the binding energy E b between two ruthenium atoms in the studied materials using the extended Hrynkiewicz-Królas idea. The extrapolated value of E b for x = 0 was used to compute the enthalpy of solution H FeRu of Ru in Fe matrix. The result was compared with corresponding values given in the literature which were derived from experimental calorimetric data as well as with the value resulting from the cellular atomic model of alloys by Miedema. It was found that all the H FeRu values are negative or Ru atoms interact repulsively. At the same time, the Mössbauer data were used to determine values of the short-range order parameter α 1. For the as-obtained samples in which atoms are frozen-in high temperature state, close to the melting point, the negative α 1 values were found. The findings indicates ordering tendencies in such specimens. On the other hand, in the case of the annealed samples where the observed distributions of atoms should be frozen-in state corresponding to the temperature 700 K, the Fe1- x Ru x alloys with x ≥ 0.05 exhibit clustering tendencies (a predominance of Fe-Fe and Ru-Ru bonds), which manifest themselves by positive values of the calculated SRO parameter. The clustering process leads to a local increase in ruthenium concentration and nucleation of a new ruthenium-rich phase with the hcp structure.

  18. A study of thermodynamic properties of dilute Fe-Ru alloys by {sup 57}Fe Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Idczak, R., E-mail: ridczak@ifd.uni.wroc.pl; Konieczny, R.; Chojcan, J. [University of Wroclaw, Institute of Experimental Physics (Poland)

    2016-12-15

    The room temperature Mössbauer spectra of {sup 57}Fe were measured for Fe{sub 1−x}Ru{sub x} solid solutions with x in the range 0.01 ≤ x ≤ 0.08. The obtained data were analysed in terms of short-range order parameter (SRO) and the binding energy E{sub b} between two ruthenium atoms in the studied materials using the extended Hrynkiewicz-Królas idea. The extrapolated value of E{sub b} for x = 0 was used to compute the enthalpy of solution H{sub FeRu} of Ru in Fe matrix. The result was compared with corresponding values given in the literature which were derived from experimental calorimetric data as well as with the value resulting from the cellular atomic model of alloys by Miedema. It was found that all the H{sub FeRu} values are negative or Ru atoms interact repulsively. At the same time, the Mössbauer data were used to determine values of the short-range order parameter α{sub 1}. For the as-obtained samples in which atoms are frozen-in high temperature state, close to the melting point, the negative α{sub 1} values were found. The findings indicates ordering tendencies in such specimens. On the other hand, in the case of the annealed samples where the observed distributions of atoms should be frozen-in state corresponding to the temperature 700 K, the Fe{sub 1−x}Ru{sub x} alloys with x ≥ 0.05 exhibit clustering tendencies (a predominance of Fe-Fe and Ru-Ru bonds), which manifest themselves by positive values of the calculated SRO parameter. The clustering process leads to a local increase in ruthenium concentration and nucleation of a new ruthenium-rich phase with the hcp structure.

  19. Ruthenium redox equilibria: 1. Thermodynamic stability of Ru(III and Ru(IV hydroxides

    Directory of Open Access Journals (Sweden)

    Igor Povar

    2016-04-01

    Full Text Available On the basis of the selected thermodynamic data for Ru(III and Ru(IV compounds in addition to original thermodynamic and graphical approach used in this paper, the thermodynamic stability areas of sparingly soluble hydroxides as well as the repartition of their soluble and insoluble chemical species towards the solution pH and initial concentrations of ruthenium in heterogeneous mixture solid phase–saturated solution have been investigated. By means of the ΔG–pH diagrams, the areas of thermodynamic stability of Ru(III and Ru(IV hydroxides have been established for a number of analytical concentrations in heterogeneous mixtures. The diagrams of heterogeneous and homogeneous chemical equilibria have been used for graphical representation of complex equilibria in aqueous solutions containing Ru(III and Ru(IV. The obtained results, based on the thermodynamic analysis and graphic design of the calculated data in the form of the diagrams of heterogeneous chemical equilibria, are in good agre­ement with the available experimental data.

  20. Synthesis, characterization, DNA binding, DNA cleavage, protein binding and cytotoxic activities of Ru(II) complexes.

    Science.gov (United States)

    Thota, Sreekanth; Vallala, Srujana; Yerra, Rajeshwar; Rodrigues, Daniel Alencar; Raghavendra, Nulgumnalli Manjunathaiah; Barreiro, Eliezer J

    2016-01-01

    We report on the synthesis of novel Ru(II) compounds (Ru-1 to Ru-8) bearing R-pdc, 4-Cl-pbinh ligands (where R=4-CF3, 4-F, 4-OH pdc=3-phenyl-5-(1H-pyrrol-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide, pbinh=phenoxybenzylidene isonicotinyl hydrazides) and their in vitro antitumor activity toward the cell lines murine leukemia L1210, human lymphocyte CEM, human epithelial cervical carcinoma HeLa, BEL-7402 and Molt4/C8. Some of the complexes exhibited more potent antiproliferative activity against cell lines than the standard drug cisplatin. Ruthenium complex Ru-2 displayed potent cytotoxicity with than that of cisplatin. DNA-binding, DNA cleavage and protein binding properties of ruthenium complexes with these ligands are reported. Interactions of these ruthenium complexes with DNA revealed an intercalative mode of binding between them. Synchronous fluorescence spectra proved that the interaction of ruthenium complexes with bovine serum albumin (BSA) resulted in a conformational change of the latter.

  1. Binding of Ru(terpyridine)(pyridine)dipyridophenazine to DNA studied with polarized spectroscopy and calorimetry.

    Science.gov (United States)

    Mårtensson, Anna K F; Lincoln, Per

    2015-02-28

    Linear and circular dichroism (LD and CD) spectroscopy as well as isothermal titration calorimetry (ITC) have been used to investigate the interaction of Ru(tpy)(py)dppz(2+) (tpy = 2,2':6',2''-terpyridyl; py = pyridine; dppz = dipyrido[3,2-a:2'3'-c]phenazine) with DNA, providing detailed information about the DNA binding thermodynamics and binding geometry of the metal complex. Flow LD, CD and isotropic absorption indicate that Ru(tpy)(py)dppz(2+) bind to DNA from the minor groove with the dppz ligand intercalated between base pairs, very similar to its chiral structural isomers Δ- and Λ-Ru(bpy)2dppz(2+) (bpy = 2,2'-bipyridine). A simple cooperative binding model with one binding geometry provide an excellent fit for calorimetric and absorption titration data. The values of the neighbor interaction thermodynamic parameters for Ru(tpy)(py)dppz(2+) suggest that complexes bound contiguously prefer to have their tpy ligands oriented towards the same strand.

  2. Lubiprostone: RU 0211, SPI 0211.

    Science.gov (United States)

    2005-01-01

    Lubiprostone [RU 0211, SPI 0211] is a bicyclic fatty acid that acts as a chloride channel opener, increasing intestinal water secretion. Lubiprostone, an orally-administered formulation, is one of a series of functional fatty acid compounds discovered by Dr Ryuji Ueno, and is currently undergoing development for the treatment of constipation, constipation-predominant irritable bowel syndrome (IBS-C) and postoperative ileus with Sucampo Pharmaceutical's. Lubiprostone activates a specific chloride channel (CLC2) on cells lining the gut, thereby naturally increasing intestinal fluid secretion. The increased fluid level softens the stool, promotes spontaneous bowel movements, and reduces abdominal discomfort/pain and bloating. The chloride channel is a protein that controls cell membrane transport of chloride ion. Lubiprostone acts on the ClC-2 chloride channel, which is located in the apical intestinal membrane. In November 2004, Takeda Pharmaceuticals entered into a collaboration and licensing agreement for Lubiprostone with Sucampo Pharmaceuticals for the treatment of chronic constipation and constipation-predominant Irritable Bowel Syndrome (c-IBS). Under the terms of the agreement, Takeda received the right to market the product in the US and Canada, while Sucampo reserved the co-promotion rights for these countries. Takeda's wholly-owned US subsidiary, Takeda Pharmaceuticals North America Inc., will sell lubiprostone once the product is approved by the US FDA. Takeda will also receive an option for marketing rights in other territories, including Japan and Europe. Takeda and Sucampo agreed on the exclusive manufacturing and supply of Lubiprostone by R-Tech Ueno, Ltd, a member of the Sucampo Group. Sucampo has the potential to receive up to dollar US 210 million in initial and milestone payments, some of which are contingent upon the successful achievement of several milestones. Takeda will fund a major part of development costs not only for chronic constipation

  3. Intervalence charge transfer transition in mixed valence complexes synthesised from RuIII(edta)- and FeII(CN)5-cores

    Indian Academy of Sciences (India)

    H C Bajaj; Atindra D Shukla; Amitava Das

    2002-08-01

    Intervalence charge transfer properties were studied for a set of mixed valence complexes incorporating Ru(III) and Fe(II)-centres linked by various saturated and unsaturated bridging ligands (BL). Studies reveal that degree of ground state electronic interaction and coupling between Ru(III) and Fe(II)-centres can be attenuated by changing the nature of the bridging ligand. Further, inclusion of the bridging ligand with interrupted -electron system in a -CD cavity initiate an optical electron transfer from Fe(II) to Ru(III) which is otherwise not observed.

  4. The degradation of Isophorone by catalytic wet air oxidation on Ru/TiZrO4.

    Science.gov (United States)

    Wei, Huangzhao; Yan, Xiaomiao; Li, Xianru; He, Songbo; Sun, Chenglin

    2013-01-15

    The catalyst Ru/TiZrO(4) was applied in the degradation of Isophorone by catalytic wet air oxidation. Mathematical models for the effects of reaction conditions on the Isophorone degradation by catalytic wet air oxidation were developed using a response surface methodology. A model was obtained for each response with multiple regression analysis and then was refined. Analysis of variance revealed that the models developed were adequate. The validity of the models was also verified by experimental data. Analysis of response surface showed that total organic carbon removal and Isophorone conversion were significantly affected (P≤0.01) by reaction time, temperature and their interactions, and affected (P≤0.05) by the square of reaction time. The point of zero charge of Ru/TiZrO(4) catalyst was about 1.72. The total organic carbon removal and Isophorone conversion had a great association with the zeta potential of Ru/TiZrO(4) catalyst. Finally, the degradation pathway of Isophorone in catalytic wet air oxidation was proposed. Within 410 h, the total organic carbon removal remained above 95%, indicating that the Ru/TiZrO(4) catalyst had a good stability.

  5. Liquid-Phase Catalytic Transfer Hydrogenation of Furfural over Homogeneous Lewis Acid-Ru/C Catalysts.

    Science.gov (United States)

    Panagiotopoulou, Paraskevi; Martin, Nickolas; Vlachos, Dionisios G

    2015-06-22

    The catalytic performance of homogeneous Lewis acid catalysts and their interaction with Ru/C catalyst are studied in the catalytic transfer hydrogenation of furfural by using 2-propanol as a solvent and hydrogen donor. We find that Lewis acid catalysts hydrogenate the furfural to furfuryl alcohol, which is then etherified with 2-propanol. The catalytic activity is correlated with an empirical scale of Lewis acid strength and exhibits a volcano behavior. Lanthanides are the most active, with DyCl3 giving complete furfural conversion and a 97 % yield of furfuryl alcohol at 180 °C after 3 h. The combination of Lewis acid and Ru/C catalysts results in synergy for the stronger Lewis acid catalysts, with a significant increase in the furfural conversion and methyl furan yield. Optimum results are obtained by using Ru/C combined with VCl3 , AlCl3 , SnCl4 , YbCl3 , and RuCl3 . Our results indicate that the combination of Lewis acid/metal catalysts is a general strategy for performing tandem reactions in the upgrade of furans.

  6. Pressure Induced Enhancement of Superconductivity in LaRu2P2

    Science.gov (United States)

    Li, Baoxuan; Lu, Pengchao; Liu, Jianzhong; Sun, Jian; Li, Sheng; Zhu, Xiyu; Wen, Hai-Hu

    2016-04-01

    To explore new superconductors beyond the copper-based and iron-based systems is very important. The Ru element locates just below the Fe in the periodic table and behaves like the Fe in many ways. One of the common thread to induce high temperature superconductivity is to introduce moderate correlation into the system. In this paper, we report the significant enhancement of superconducting transition temperature from 3.8 K to 5.8 K by using a pressure only of 1.74 ± 0.05 GPa in LaRu2P2 which has an iso-structure of the iron-based 122 superconductors. The ab-initio calculation shows that the superconductivity in LaRu2P2 at ambient pressure can be explained by the McMillan’s theory with strong electron-phonon coupling. However, it is difficult to interpret the enhancement of Tc versus pressure within this picture. Detailed analysis of the pressure induced evolution of resistivity and upper critical field Hc2(T) reveals that the increase of Tc with pressure may be accompanied by the involvement of extra electron-boson interaction. This suggests that the Ru-based system has some commonality as the Fe-based superconductors.

  7. Ru nanostructure fabrication using an anodic aluminum oxide nanotemplate and highly conformal Ru atomic layer deposition.

    Science.gov (United States)

    Kim, Woo-Hee; Park, Sang-Joon; Son, Jong-Yeog; Kim, Hyungjun

    2008-01-30

    We fabricated metallic nanostructures directly on Si substrates through a hybrid nanoprocess combining atomic layer deposition (ALD) and a self-assembled anodic aluminum oxide (AAO) nanotemplate. ALD Ru films with Ru(DMPD)(EtCp) as a precursor and O(2) as a reactant exhibited high purity and low resistivity with negligible nucleation delay and low roughness. These good growth characteristics resulted in the excellent conformality for nanometer-scale vias and trenches. Additionally, AAO nanotemplates were fabricated directly on Si and Ti/Si substrates through a multiple anodization process. AAO nanotemplates with various hole sizes (30-100 nm) and aspect ratios (2:1-20:1) were fabricated by controlling the anodizing process parameters. The barrier layers between AAO nanotemplates and Si substrates were completely removed by reactive ion etching (RIE) using BCl(3) plasma. By combining the ALD Ru and the AAO nanotemplate, Ru nanostructures with controllable sizes and shapes were prepared on Si and Ti/Si substrates. The Ru nanowire array devices as a platform for sensor devices exhibited befitting properties of good ohmic contact and high surface/volume ratio.

  8. Laser Spectroscopy of Ruthenium Containing Diatomic Molecules: RuH/D and RuP.

    Science.gov (United States)

    Adam, Allan G.; Konder, Ricarda M.; Nickerson, Nicole M.; Linton, Colan; Tokaryk, D. W.

    2015-06-01

    In the last few years, the Cheung group in Hong Kong and the Steimle group in Arizona have successfully studied several ruthenium containing diatomic molecules, RuX (X =C, O, N, B, using the laser-ablation molecular jet technique. Based on this success, the UNB spectroscopy group decided to try and find the optical signatures of other RuX molecules. Using CH_3OH and PH_3 as reactant gases, the RuH and RuP diatomic molecules have been detected in surveys of the 420 - 675 nm spectral region. RuD has also been made using fully deuterated methanol as a reactant. Dispersed fluorescence experiments have been performed to determine ground state vibrational frequencies and the presence of any low-lying electronic states. Rotationally resolved spectra for these molecules have also been taken and the analysis is proceeding. The most recent results will be presented. F. Wang et al., Journal of Chemical Physics 139, 174318 (2013). N. Wang et al., Journal of Physical Chemistry A 117, 13279 (2013). T. Steimle et al., Journal of Chemical Physics 119, 12965 (2003). N. Wang et al., Chemical Physics Letters 547, 21 (2012).

  9. Mifepristone (RU 486) treatment of meningiomas.

    OpenAIRE

    Lamberts, S.W.; Tanghe, H L; Avezaat, C J; Braakman, R; Wijngaarde, R.; Koper, J. W.; de Jong, H

    1992-01-01

    Meningiomas are common brain tumours which are generally benign, well circumscribed and slow growing. In a minority of patients complete surgical removal is not possible and re-growth of tumour tissue is a major clinical problem. Most meningiomas contain progesterone receptors. The anti-progestational drug mifepristone (RU 486) binds to these receptors. Ten patients were treated with 12 recurrent or primary "inoperable" meningiomas, all of whom had shown recent neuroradiological and/or ophtha...

  10. LDA+DMFT study of (Sr, Ca){sub n+1}Ru{sub n}O{sub 3n+1} ruthenates

    Energy Technology Data Exchange (ETDEWEB)

    Gorelov, Evgeny; Pavarini, Eva [IFF, IAS, Forschungszentrum Juelich, 52425 Juelich (Germany)

    2011-07-01

    The ruthenates of the Ruddelsen-Popper series (Sr, Ca){sub n+1}Ru{sub n}O{sub 3n+1} are unique among transition-metal oxides: changes in the number of RuO{sub 2} layers, Sr/Ca content and temperature lead to a variety of different properties, ranging from Mott insulating behavior and orbital order to metallic ferro- and meta- magnetism. In order to understand how structural changes affect the properties, we perform and LDA+DMFT calculations for material-specific Hubbard models describing the partially filled Ru4d{sup 4} shells. Since the e{sub g} Ru bands are well above the Fermi level, we consider only the t{sub 2g} bands. For n=3 the unit cell contains two inequivalent Ru atoms, thus for this system we perform six-orbital LDA+cDMFT calculations. The LDA+cDMFT scheme used is based on the ab-initio NMTO downfolding procedure and a weak-coupling CT-QMC impurity solver with full rotationally-invariant Coulomb interaction. We use a self-energy matrix in orbital space - {sigma}{sub ij}. We identify the main difference among the materials in a substantial rearrangement of Ru t{sub 2g} occupations, controlled by the interplay between Coulomb repulsion, number of RuO{sub 2} layers n, which reflects effective dimensionality, and changes in the t{sub 2g} crystal field.

  11. Pt Ru/C electrocatalysts prepared using electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F.; Oliveira Neto, Almir; Pino, Eddy S.; Brandalise, Michele; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)]. E-mails: dfsilva@ipen.br; espinace@ipen.br

    2007-07-01

    Pt Ru/C electrocatalysts (carbon-supported Pt Ru nanoparticles) were prepared submitting water/ethylene glycol solutions containing Pt(IV) and Ru(III) ions and the carbon support to electron beam irradiation. The water/ethylene glycol ratio (v/v) was evaluated as synthesis parameters. The Pt Ru/C electrocatalysts were prepared with a nominal Pt:Ru atomic ratio of 50:50 and were characterized by energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) and tested for methanol electro-oxidation using cyclic voltammetry and chronoamperometry. The obtained Pt Ru/C electrocatalysts showed the typical fcc structure of platinum-ruthenium alloys and the electrocatalytic activity depends on the water/ethylene glycol ratio used in the preparation.

  12. Reaction mechanism of Ru(II) piano-stool complexes: umbrella sampling QM/MM MD study.

    Science.gov (United States)

    Futera, Zdeněk; Burda, Jaroslav V

    2014-07-15

    Biologically relevant interactions of piano-stool ruthenium(II) complexes with ds-DNA are studied in this article by hybrid quantum mechanics-molecular mechanics (QM/MM) computational technique. The whole reaction mechanism is divided into three phases: (i) hydration of the [Ru(II) (η(6) -benzene)(en)Cl](+) complex, (ii) monoadduct formation between the resulting aqua-Ru(II) complex and N7 position of one of the guanines in the ds-DNA oligomer, and (iii) formation of the intrastrand Ru(II) bridge (cross-link) between two adjacent guanines. Free energy profiles of all the reactions are explored by QM/MM MD umbrella sampling approach where the Ru(II) complex and two guanines represent a quantum core, which is described by density functional theory methods. The combined QM/MM scheme is realized by our own software, which was developed to couple several quantum chemical programs (in this study Gaussian 09) and Amber 11 package. Calculated free energy barriers of the both ruthenium hydration and Ru(II)-N7(G) DNA binding process are in good agreement with experimentally measured rate constants. Then, this method was used to study the possibility of cross-link formation. One feasible pathway leading to Ru(II) guanine-guanine cross-link with synchronous releasing of the benzene ligand is predicted. The cross-linking is an exergonic process with the energy barrier lower than for the monoadduct reaction of Ru(II) complex with ds-DNA. Copyright © 2014 Wiley Periodicals, Inc.

  13. Ruthenium redox equilibria 1. Thermodynamic stability of Ru(III) and Ru(IV) hydroxides

    OpenAIRE

    Igor Povar; Oxana Spinu

    2016-01-01

    On the basis of the selected thermodynamic data for Ru(III) and Ru(IV) compounds in addition to original thermodynamic and graphical approach used in this paper, the thermodynamic stability areas of sparingly soluble hydroxides as well as the repartition of their soluble and insoluble chemical species towards the solution pH and initial concentrations of ruthenium in heterogeneous mixture solid phase–saturated solution have been investigated. By means of the ΔG–pH diagrams, the areas of therm...

  14. Sideward flow of $K^{+}$ mesons in Ru+Ru and Ni+Ni reactions near threshold

    CERN Document Server

    Crochet, Philippe; Wisniewski, K; Leifels, Y; Andronic, A; Averbeck, R; Devismes, A; Finck, C; Gobbi, A; Hartmann, O; Hildenbrand, K D; Koczón, P; Kress, T; Kutsche, R; Reisdorf, W; Schull, D; Alard, J P; Barret, V; Basrak, Z; Bastid, N; Belyaev, I; Bendarag, A; Berek, G; Caplar, R; Cindro, N; Dupieux, P; Dzelalija, M; Eskef, M; Fodor, Z; Grishkin, Yu L; Hong, B; Kecskeméti, J; Kim, Y J; Kirejczyk, M; Korolija, M; Kotte, R; Kowalczyk, M; Lebedev, A; Lee, K S; Man'ko, V I; Merlitz, H; Mohren, S; Moisa, D; Neubert, W; Nyanin, A; Pelte, D; Petrovici, M; Plettner, C; Rami, F; De Schauenburg, B; Seres, Z; Sikora, B; Sim, K S; Simion, V; Siwek-Wilczynska, K; Smolyankin, V T; Somov, A; Stockmeier, M R; Stoicea, G; Vasilev, M A; Wagner, P; Wohlfarth, D; Yang, J T; Yushmanov, I E; Zhilin, A V

    2000-01-01

    Experimental data on K+ meson and proton sideward flow measured with the FOPI detector at SIS/GSI in the reactions Ru+Ru at 1.69 AGeV and Ni+Ni at 1.93 AGeV are presented. The K+ sideward flow is found to be anti-correlated (correlated) with the one of protons at low (high) transverse momenta. When compared to the predictions of a transport model, the data favour the existence of an in-medium repulsive K+ nucleon potential.

  15. Lanthanum-Promoted Ru/Sepiolite in Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    Le Zhiping; Lin Jianxin; Yu Xiujin; Huang Yueyu; Wei Kemei

    2005-01-01

    A new kind of Ru supported on sepiolite catalyst with La as promoter for ammonia synthesis was prepared. The effects of reaction conditions on catalytic activity were discussed. The result shows that La is an effective promoter for sepiolite-supported Ru based catalyst. When the load of Ru is 5% (mass fraction), and the molar ratio of La/Ru is 1.5, under the condition of 10 MPa 450 ℃ 20000 h-1, the ammonia synthesis rate is 38.5 mmol NH3·g-1·h-1.

  16. Hyperfine specific heats of PrX 2 ( X = Ir, Pt, Rh, Ru) laves phase compounds

    Science.gov (United States)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1980-01-01

    Specific heat data below 1 K for the C-15 compounds PrX 2 (X = Ir, Pt, Rh, Ru) reveal Schottky-type anomalies, ascribed to hyperfine interactions. Apparently the 4f-moments are magnetically ordered. The values deduced for these moments are only ≈ 70% of that for J = 4, indicating that the Pr 3+ moment is partially quenched by the crystal field.

  17. Thermodynamic assessment of the Pd−Rh−Ru system using calphad and first-principles methods

    Energy Technology Data Exchange (ETDEWEB)

    Gossé, S., E-mail: stephane.gosse@cea.fr [DEN-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Dupin, N. [Calcul Thermodynamique, Rue de l' avenir, 63670, Orcet (France); Guéneau, C. [DEN-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME), CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Crivello, J.-C.; Joubert, J.-M. [Chimie Métallurgique des Terres Rares, Université Paris Est, ICMPE (UMR 7182), CNRS, UPEC, F-94320, Thiais (France)

    2016-06-15

    Palladium, rhodium and ruthenium are abundant fission products that form in oxide fuels in nuclear reactors. Under operating conditions, these Platinum-Group Metal (PGM) fission products accumulate in high concentration at the rim of the oxide fuel and mainly precipitate into metallic solid solutions. Their thermochemistry is of significant interest to predict the high temperature chemical interactions between the fuel and the cladding or the possible precipitation of PGM phases in high level nuclear waste glasses. To predict the thermodynamic properties of these PGM fission products, a thermodynamic modeling is being developed on the ternary Pd−Rh−Ru system using the Calphad method. Because experimental thermodynamic data are scarce, Special Quasirandom Structures coupled with Density Functional Theory methods were used to calculate mixing enthalpy data in the solid solutions. The resulting thermodynamic description based on only binary interaction parameters is in good agreement with the few data on the ternary system. - Highlights: • The mixing enthalpy of solid solutions in the Pd−Rh−Ru system was calculated using the DFT and SQS methods. • A thermodynamic assessment of the Pd−Rh−Ru ternary system was performed using the Calphad method. • The extrapolation based on only binary interaction parameters leads to a good agreement with the data on the ternary.

  18. Formation of metastable, heterolytic H-pairs on the RuO2(110) surface

    DEFF Research Database (Denmark)

    Wei, Yinying; Martinez, Umberto; Lammich, Lutz;

    2014-01-01

    The interaction of molecular hydrogen (H-2) with the stoichiometric RuO2(110) surface was studied at various temperatures and coverages by high-resolution scanning tunneling microscopy (STM) and temperature-programmed reaction (TPR). Metastable, heterolytic H-pairs of dissociated H-2 consisting...

  19. Large exchange bias effect in LaCr0.9Ru0.1O3

    Science.gov (United States)

    Sarkar, Babusona; Dalal, Biswajit; De, S. K.

    2016-11-01

    The incorporation of tetravalent Ru (10%) into antiferromagnetic spin structure of LaCrO3 leads to mixed valence states of Cr (Cr2+ and Cr3+). Highly delocalized 4d orbital of Ru induces prominent ferromagnetic (FM) component in antiferromagnetic (AFM) matrix of parent compound. The complex magnetic interaction across the interface of FM and AFM regions gives rise to large exchange bias field (HEB) of about 10 kOe. The inverse and normal magnetocaloric effect for magnetic field up to 50 kOe coexists in a single material due to multiple magnetic phase transitions with temperature.

  20. Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon

    Energy Technology Data Exchange (ETDEWEB)

    Wu Gang [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: wugang@lanl.gov; Swaidan, Raja [Department of Chemical Engineering, Cooper Union, New York, NY 10003 (United States); Li Deyu; Li Ning [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

    2008-11-01

    A typical heteroatom (nitrogen)-doped carbon materials were successfully synthesized through the carbonization of a hybrid containing traditional carbon black covered by in situ polymerized polyaniline. The nitrogen content onto carbon can be adjusted up to 5.1 at.% by changing the coverage of polyaniline. The effects of nitrogen doping on the surface physical and electrochemical properties of carbon were studied using XPS, XRD and HRTEM, as well as CV and EIS techniques. With increasing nitrogen doping, the carbon structure became more compact, showing curvatures and dislocations in the graphene stacking. The nitrogen-doped carbon also exhibited a higher accessible surface area in electrochemical reactions, and a lower charge transfer resistance at the carbon/electrolyte interface. Moreover, to investigate the influence of nitrogen doping on the electrocatalytic activity of the PtRu/C catalyst, comparisons in CO stripping and methanol oxidation were carried out on PtRu catalysts supported by non-doped and nitrogen-doped carbon. Since the promotional roles of nitrogen doping, including the high electrochemically accessible surface area, the richness of the disordered nanostructures and defects, and the high electron density on N-doped carbon supports, contribute to the synthesis of well-dispersed PtRu particles with high Pt utilization and stronger metal-support interactions, an enhanced catalytic activity for methanol oxidation was obtained in the case of the PtRu/N-C catalyst in comparison with the traditional PtRu/C catalyst.

  1. Enhanced methanol electro-oxidation activity of PtRu catalysts supported on heteroatom-doped carbon

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Gang; Li, Deyu; Li, Ning [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Swaidan, Raja [Department of Chemical Engineering, Cooper Union, New York, NY 10003 (United States)

    2008-11-01

    A typical heteroatom (nitrogen)-doped carbon materials were successfully synthesized through the carbonization of a hybrid containing traditional carbon black covered by in situ polymerized polyaniline. The nitrogen content onto carbon can be adjusted up to 5.1 at.% by changing the coverage of polyaniline. The effects of nitrogen doping on the surface physical and electrochemical properties of carbon were studied using XPS, XRD and HRTEM, as well as CV and EIS techniques. With increasing nitrogen doping, the carbon structure became more compact, showing curvatures and dislocations in the graphene stacking. The nitrogen-doped carbon also exhibited a higher accessible surface area in electrochemical reactions, and a lower charge transfer resistance at the carbon/electrolyte interface. Moreover, to investigate the influence of nitrogen doping on the electrocatalytic activity of the PtRu/C catalyst, comparisons in CO stripping and methanol oxidation were carried out on PtRu catalysts supported by non-doped and nitrogen-doped carbon. Since the promotional roles of nitrogen doping, including the high electrochemically accessible surface area, the richness of the disordered nanostructures and defects, and the high electron density on N-doped carbon supports, contribute to the synthesis of well-dispersed PtRu particles with high Pt utilization and stronger metal-support interactions, an enhanced catalytic activity for methanol oxidation was obtained in the case of the PtRu/N-C catalyst in comparison with the traditional PtRu/C catalyst. (author)

  2. Tuning of interlayer exchange coupling in Ni80Fe20/Ru/Ni80Fe20 nanowires

    Science.gov (United States)

    Liu, X. M.; Lupo, P.; Cottam, M. G.; Adeyeye, A. O.

    2015-09-01

    In this work, we demonstrate how the static and dynamic properties of Ni80Fe20/Ru/Ni80Fe20 nanowires can be tuned by varying the Ru spacer layer thickness. Specifically, changing the Ru thickness we have tuned the Ruderman-Kittel-Kasuya-Yosida exchange interaction, and thus the antiferromagnetic (AFM) strength between the Ni80Fe20 layers. We show that there is a strong correlation between the interlayer coupling and features in ferromagnetic resonance (FMR) modes. We found different mode-softening degree of the FMR curves as function of the strength of AFM coupling, together with a clear frequency gap at around zero field. These experimental results are in qualitative agreement with presented micromagnetic simulations that also include biquadratic interface exchange. Understanding these characteristics may offer insights for reconfigurable vertical magnetic logic devices and microwave filters.

  3. Study of the Pt/Ru(0001) Interface

    DEFF Research Database (Denmark)

    Godowski, Jan P; Li, Zhe Shen; Bork, Jakob

    2007-01-01

    The growth process of platinum on Ru(0001) near room temperature was characterized using photoelectron spectroscopy of high resolution. The binding energy position and intensity of the Pt 4f7/2 and Ru 3d5/2 core levels as well as the shape and structure of the valence band spectra corresponding t...

  4. Ru Nanoframes with an fcc Structure and Enhanced Catalytic Properties.

    Science.gov (United States)

    Ye, Haihang; Wang, Qingxiao; Catalano, Massimo; Lu, Ning; Vermeylen, Joseph; Kim, Moon J; Liu, Yuzi; Sun, Yugang; Xia, Xiaohu

    2016-04-13

    Noble-metal nanoframes are of great interest to many applications due to their unique open structures. Among various noble metals, Ru has never been made into nanoframes. In this study, we report for the first time an effective method based on seeded growth and chemical etching for the facile synthesis of Ru nanoframes with high purity. The essence of this approach is to induce the preferential growth of Ru on the corners and edges of Pd truncated octahedra as the seeds by kinetic control. The resultant Pd-Ru core-frame octahedra could be easily converted to Ru octahedral nanoframes of ∼2 nm in thickness by selectively removing the Pd cores through chemical etching. Most importantly, in this approach the face-centered cubic (fcc) crystal structure of Pd seeds was faithfully replicated by Ru that usually takes an hcp structure. The fcc Ru nanoframes showed higher catalytic activities toward the reduction of p-nitrophenol by NaBH4 and the dehydrogenation of ammonia borane compared with hcp Ru nanowires with roughly the same thickness.

  5. Dramatic destabilization of the Ru(0001) surface upon oxygen adsorption

    Science.gov (United States)

    Reuter, K.; Ganduglia-Pirovano, M. V.; Scheffler, M.; Stampfl, C.

    2000-03-01

    Under high oxygen pressures, where most other transition metal surfaces typically form inert surface oxides, Ru(0001) displays the highest rates for oxidation reactions. This unusual behavior has been attributed to the fact that Ru can exist in different oxidation states and to the ease with which its surface can be loaded with high concentrations of subsurface oxygen. Yet, recent experiments have also indicated that high oxygen loads in the subsurface region destabilize Ru(0001) and lead to the emission of RuOx (xA. Böttcher, H. Conrad and H. Niehus, J. Chem. Phys. (submitted).). We perform density functional theory calculations to gain a fundamental understanding of the O-Ru bond in on-surface as well as subsurface oxygen phases. After completion of a full monolayer coverage on the surface, Ru(0001) is found to strongly bind even up to another full monolayer in the sites directly below the first substrate layer. In agreement with the experimental findings, this highly loaded O-Ru-O fringe is then relatively instable against lift-off, which might lead to either RuOx fragmentation or restructuring. The relation between charge transfer towards the oxygen and bond formation, as well as substrate destabilization is discussed.

  6. Electronic structure of Fe- vs. Ru-based dye molecules

    DEFF Research Database (Denmark)

    Johnson, Phillip S.; Cook, Peter L.; Zegkinoglou, Ioannis;

    2013-01-01

    In order to explore whether Ru can be replaced by inexpensive Fe in dye molecules for solar cells, the differences in the electronic structure of Fe- and Ru-based dyes are investigated by X-ray absorption spectroscopy and first-principles calculations. Molecules with the metal in a sixfold...

  7. Ru isotope heterogeneity in the solar protoplanetary disk

    Science.gov (United States)

    Fischer-Gödde, Mario; Burkhardt, Christoph; Kruijer, Thomas S.; Kleine, Thorsten

    2015-11-01

    Nucleosynthetic isotope anomalies in bulk chondrites and differentiated meteorites reflect variable proportions of isotopically diverse presolar components in bulk planetary bodies, but the origin of these heterogeneities is not well understood. Here, the Ru isotope composition of a comprehensive suite of iron meteorites and bulk samples of ordinary, enstatite and carbonaceous chondrites, as well as acid leachates and an insoluble residue of the Allende chondrite are examined using newly developed multi-collector inductively coupled plasma mass spectrometry techniques. Except for IAB iron meteorites and enstatite chondrites, all investigated meteorites show well-resolved Ru isotope anomalies. Of these, within-group Ru isotopic variations observed for samples from a given chemical group of iron meteorites reflect secondary neutron capture induced Ru isotope shifts during prolonged cosmic ray-exposure. After correction of these cosmogenic effects using Pt isotopes as a neutron-dose monitor, the remaining Ru isotope anomalies are nucleosynthetic in nature and are consistent with a deficit in s-process Ru in iron meteorite parent bodies. Similarly, Ru isotope anomalies in bulk ordinary and carbonaceous chondrites also reflect a deficiency in s-process Ru. The sequential dissolution of Allende reveals the presence of an HF-soluble s-process carrier, which is either an unidentified presolar phase or a component that incorporated s-process Ru liberated from SiC grains during nebular or parent body processes. We show that varying proportions of the s-process carrier identified in Allende resulted in the correlated Ru isotope anomalies observed for bulk meteorites, and that all meteorites (except possibly IAB irons and enstatite chondrites) are depleted in this s-process component relative to Ru from the Earth's mantle. Bulk meteorites exhibit correlated Ru and Mo isotope anomalies, reflecting variable deficits of a common s-process component, but some iron meteorites and

  8. Bifunctional electrocatalysis in pt-ru nanoparticle systems.

    Science.gov (United States)

    Roth, C; Benker, N; Theissmann, R; Nichols, R J; Schiffrin, D J

    2008-03-04

    Pt-Ru alloys are prominent electrocatalysts in fuel cell anodes as they feature a very high activity for the oxidation of reformate and methanol. The improved CO tolerance of these alloys has been discussed in relation to the so-called ligand and bifunctional mechanisms. Although these effects have been known for many years, they are still not completely understood. A new approach that bridges the gap between single crystals and practical catalysts is presented in this paper. Nanoparticulate model systems attached to an oxidized glassy carbon electrode were prepared by combining both ligand-stabilized and spontaneously deposited Pt and Ru nanoparticles. These electrodes showed very different voltammetric responses for CO and methanol oxidation. The cyclic voltammograms were deconvoluted into contributions attributed to Pt, Ru, and Pt-Ru contact regions to quantify the contribution of the latter to the bifunctional mechanism. Scanning transmission electron microscopy confirmed the proximity of Pt and Ru nanoparticles in the different samples.

  9. EFFECT OF MIFEPRISTONE (RU486) ON MARKERS OF ENDOMETRIAL RECEPTIVITY

    Institute of Scientific and Technical Information of China (English)

    武捷; 王龙生; 程捷; 王介东

    2003-01-01

    Objective To study the effect of single and low dose of RU486 on endometrial receptivity of healthy women. Methods A total of 5 healthy women were followed for one control and one treatment cycle. In the treatment cycle, a dose of 10 mg RU486 was administered on day luteinizing hormone (LH)-2. In both the control and treatment cycle, an endometrial biopsy was obtained on LH+7. These biopsies were assessed by immunohistochemical analysis to find the difference in expression of integrins and progesterone receptor (PR) between the control and treatment cycle. Results The treatment with RU486 increased the expression of α1 and α4 subunits of integrin in glandular epithelial cells, but did not influence β3 subunit. Moreover, the normal down-regulation of PR in epitherial cell nuclei was inhibited by 10 mg RU486. Conclusion Single dose of 10 mg RU486 impairs the establishment of endometrial receptivity on time.

  10. PtRu/C electrocatalysts prepared using {gamma}-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Dionisio F.; Neto, Almir Oliveira; Pino, Eddy S.; Linardi, Marcelo; Spinace, Estevam V. [Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP, Av. Professor Lineu Prestes, 2242, Cidade Universitaria, 05508-000 Sao Paulo, SP (Brazil)

    2007-07-10

    PtRu/C electrocatalysts (carbon-supported PtRu nanoparticles) were prepared submitting water/ethylene glycol solutions containing Pt(IV) and Ru(III) ions and the carbon support to {gamma}-irradiation. The water/ethylene glycol ratio (v/v) and the total dose (kGy) were evaluated as synthesis parameters. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and cyclic voltammetry and tested for methanol electro-oxidation aiming fuel cell application. The obtained PtRu/C electrocatalysts were more active for methanol electro-oxidation than the commercial PtRu/C electrocatalyst at ambient temperature and the electrocatalytic activity depends on the water/ethylene glycol ratio used in the preparation. (author)

  11. Pressure effect on elastic properties in SmRu{sub 4}P{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Sun, P. [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan)]. E-mail: psun@iwate-u.ac.jp; Nakanishi, Y. [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Nakamura, M. [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan); Ohashi, M. [Department of Physics, Kyushu University, Fukuoka 810-8560 (Japan); Oomi, G. [Department of Physics, Kyushu University, Fukuoka 810-8560 (Japan); Sekine, C. [Faculty of Engineering, Muroran Institute of Technology, Muroran 050-8585 (Japan); Shirotani, I. [Faculty of Engineering, Muroran Institute of Technology, Muroran 050-8585 (Japan); Yoshizawa, M. [Graduate School of Engineering, Iwate University, Morioka 020-8551 (Japan)

    2007-03-15

    We investigated the elastic properties of the filled skutterudite compound SmRu{sub 4}P{sub 12} under hydrostatic pressures. Elastic softening above the metal-insulator transition T{sub MI} is enhanced by applying pressures, especially in the transverse elastic constant C{sub T}. The enhanced elastic softening suggests quadrupole moment may be one of the possible ordering parameters below T{sub MI}. Strangely, the softening is not a monotonic evolution with respect to pressure; the strongest softening is observed under pressure of 0.6GPa in C{sub T}. Jahn-Teller energy E{sub JT} and quadrupolar interaction T{sub Q} also display anomalies around this pressure. This experimental fact suggests a strong interplay between the metal-insulator transition and the subsequent magnetic phase transition in SmRu{sub 4}P{sub 12}.

  12. Vibrational contributions to phase stability in the Mo-Ru system

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, Sean H.; Abrecht, David G.; Clark, Richard A.; Schwantes, Jon M.

    2016-12-01

    Density functional theory using the Perdew-Burke-Ernzerhof functional and the small displacement method was used to calculate the quasiharmonic phonon density of states (DOS) for 69 ordered structures in the Mo-Ru substitutional alloy system to estimate the effect of vibrational contributions to the free energy of formation. These structures were used to determine interaction parameters in the cluster expansion approximation up to triplet sets to incorporate the vibrational contribution into the configurational energy of formation for the randomly mixed system. The free energies calculated using this approximation are shown to resolve lingering disagreement between reported theoretical and experimental results, and the stabilizing effect of vibrational entropy is observed to improve theoretical predictions of the Mo-Ru phase diagram.

  13. Fischer–Tropsch Synthesis: Effect of Reducing Agent for Aqueous-Phase Synthesis Over Ru Nanoparticle and Supported Ru Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pendyala, Venkat Ramana Rao [Univ. of Kentucky, Lexington, KY (United States); Shafer, Wilson D. [Univ. of Kentucky, Lexington, KY (United States); Jacobs, Gary [Univ. of Kentucky, Lexington, KY (United States); Graham, Uschi M. [Univ. of Kentucky, Lexington, KY (United States); Khalid, Syed [Brookhaven National Lab. (BNL), Upton, NY (United States); Davis, Burtron H. [Univ. of Kentucky, Lexington, KY (United States)

    2014-12-27

    The effect of the reducing agent on the performance of a ruthenium nanoparticle catalyst was investigated during aqueous-phase Fischer–Tropsch synthesis using a 1 L stirred tank reactor in the batch mode of operation. For the purpose of comparison, the activity and selectivity of NaY zeolite supported Ru catalyst were also studied. NaBH4 and hydrogen were used as reducing agents in our study, and hydrogen reduced catalysts exhibited higher activities than the NaBH4 reduced catalysts, because of higher extent of reduction and a relatively lower tendency toward agglomeration of Ru particles. The Ru nanoparticle catalyst displayed higher activities than the NaY zeolite supported Ru catalyst for both reducing agents. NaBH4 reduced catalysts are less active and the carbon dioxide selectivity is higher than the hydrogen reduced catalysts. The activity of the supported Ru catalyst (Ru/NaY) was 75 % of that of the Ru nanoparticle catalyst, and has the benefit of easy wax/catalyst slurry separation by filtration. Finally, the hydrogen reduced supported Ru catalyst exhibited superior selectivity towards hydrocarbons (higher C5+ selectivity and lower selectivity to methane) than all other catalysts tested.

  14. Electronic structure of the pure and Ti-doped Sr2RuO4 superconductor obtained by the embedded cluster method

    Science.gov (United States)

    Kaplan, Ilya G.; Soullard, Jacques

    2007-11-01

    Electronic structure of the pure and Ti-doped Sr2RuO4 superconductor is studied by the embedded cluster method at the Hartree-Fock (HF) and the second-order Møller-Plesset perturbation theory (MP2) electron correlation levels. The representative cluster was embedded into the Madelung potential that mimics a real crystal. The interatomic interaction leads to an effective electron transfer from O to Ru at both the HF and MP2 levels. At the MP2 level, we obtained the Ru charge equal to +1.57 , instead of +4 in the formal valence (ionic) model. The eg level, which was assumed empty in most of the previous studies, was found partly populated. The Ti substitution almost does not change the atomic charges, but induces the essential charge redistribution between d orbitals of Ru that leads to an increase of the eg population. A drastic effect of the Ti impurity on the spin density distribution was revealed; it strongly depends on the electron correlation. In undoped crystals, the MP2 spin density is located only on the Ru and Sr atoms. In the Ti-substituted crystals, the local spin density near an impurity disappears on Sr and localizes on Ru and four O atoms, surrounding it, on orbitals directed along the z axis. The latter are in complete agreement with experiments by Maeno and co-workers [Phys. Rev. B 63, 180504(R) (2001); Phys. Rev. Lett. 88, 197002 (2002)].

  15. Photophysical properties of [Ru(2,2‧-bipyridine)3]2+ encapsulated within the Uio-66 zirconium based metal organic framework

    Science.gov (United States)

    Larsen, Randy W.; Wojtas, Lukasz

    2017-03-01

    The ability to encapsulate photo-active guest molecules within the pores of metal organic frameworks (MOFs) affords the opportunity to develop robust photocatalysts as well as solar energy conversion systems. An important criteria for such systems is stability of the new materials towards moisture, high temperatures, etc which preclude the use of many MOF frameworks. Here, the ability to encapsulate [Ru(II)(2,2‧-bipyridine)3]2+([Ru(bpy)3]2+) into the cavities of the zirconium based MOF Uio-66 as well as the photophysical properties of the complex are reported. The X-ray powder diffraction data of the orange Uio-66 powder are consistent with the formation of Uio-66 in the presence of [Ru(bpy)3]2+. The steady state emission exhibits a significant bathochromic shift from 603 nm in ethanol to 610 nm in Uio-66. The corresponding emission decay of the encapsulated [Ru(bpy)3]2+ complex is biexponential with a fast component of 128 ns and a slower component of 1176 ns (20 deg C). The slow component is consistent with encapsulation of [Ru(bpy)3]2+ into cavities with restricted volume that prevents the population of a triplet ligand field transition that is anti-bonding with respect to the Ru-N bonds. The origin of the fast component is unclear but may involve interactions of the [Ru(bpy)3]2+ encapsulated within large cavities formed through missing ligand defect sites within the Uio-66 materials. Co-encapsulated quenchers contained within these larger cavities gives rise to the reduced lifetimes of the [Ru(bpy)3]2+ complexes.

  16. Bandgap renormalization and work function tuning in MoSe2/hBN/Ru(0001) heterostructures

    Science.gov (United States)

    Zhang, Qiang; Chen, Yuxuan; Zhang, Chendong; Pan, Chi-Ruei; Chou, Mei-Yin; Zeng, Changgan; Shih, Chih-Kang

    2016-12-01

    The van der Waals interaction in vertical heterostructures made of two-dimensional (2D) materials relaxes the requirement of lattice matching, therefore enabling great design flexibility to tailor novel 2D electronic systems. Here we report the successful growth of MoSe2 on single-layer hexagonal boron nitride (hBN) on the Ru(0001) substrate using molecular beam epitaxy. Using scanning tunnelling microscopy and spectroscopy, we found that the quasi-particle bandgap of MoSe2 on hBN/Ru is about 0.25 eV smaller than those on graphene or graphite substrates. We attribute this result to the strong interaction between hBN/Ru, which causes residual metallic screening from the substrate. In addition, the electronic structure and the work function of MoSe2 are modulated electrostatically with an amplitude of ~0.13 eV. Most interestingly, this electrostatic modulation is spatially in phase with the Moiré pattern of hBN on Ru(0001) whose surface also exhibits a work function modulation of the same amplitude.

  17. Compatibility of RuO2 electrodes with PZT ceramics

    Indian Academy of Sciences (India)

    K T Jacob; G Rajitha; V S Saji

    2009-06-01

    Because of its high electrical conductivity and good diffusion barrier properties ruthenium dioxide (RuO2) is a good electrode material for use with ferroelectric lead zirconate–titanate (PZT) solid solutions. Under certain conditions, RuO2 can react with PZT to form lead ruthenate (Pb2Ru2O6.5) during processing at elevated temperatures resulting in lead depletion from PZT. The standard Gibbs energies of formation of RuO2 and Pb2Ru2O6.5 and activities of components of the PZT solid solution have been determined recently. Using this data along with older thermodynamic information on PbZrO3 and PbTiO3, the stability domain of Pb2Ru2O6.5 is computed as a function of PZT composition, temperature and oxygen partial pressure in the gas phase. The results show PbZrO3-rich compositions are more prone to react with RuO2 at all temperatures. Increasing temperature and decreasing oxygen partial pressure suppress the reaction. Graphically displayed are the reaction zones as a function of oxygen partial pressure and PZT composition at temperatures 973, 1173 and 1373 K.

  18. Fabrication of metal nanoclusters on graphene grown on Ru(0001)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; FU Qiang; CUI Yi; TAN DaLi; BAO XinHe

    2009-01-01

    Monolayer graphene was epitaxially grown on Ru(0001) through exposure of the Ru(0001) to ethylene at room temperature followed by annealing in ultrahigh vacuum at elevated temperatures. The resulting graphene structures were studied by scanning tunneling microscopy (STM), X-ray photoelectron spec-troscopy (XPS), and ultraviolet photoelectron spectroscopy (UPS). The graphene/Ru(0001) surface was used as a periodic template for growth of metal nanoclusters. Highly dispersed Pt clusters with well controlled size and spatial distribution were fabricated on the surface.

  19. Ordered Porous Pd Octahedra Covered with Monolayer Ru Atoms.

    Science.gov (United States)

    Ge, Jingjie; He, Dongsheng; Bai, Lei; You, Rui; Lu, Haiyuan; Lin, Yue; Tan, Chaoliang; Kang, Yan-Biao; Xiao, Bin; Wu, Yuen; Deng, Zhaoxiang; Huang, Weixin; Zhang, Hua; Hong, Xun; Li, Yadong

    2015-11-25

    Monolayer Ru atoms covered highly ordered porous Pd octahedra have been synthesized via the underpotential deposition and thermodynamic control. Shape evolution from concave nanocube to octahedron with six hollow cavities was observed. Using aberration-corrected high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy, we provide quantitative evidence to prove that only a monolayer of Ru atoms was deposited on the surface of porous Pd octahedra. The as-prepared monolayer Ru atoms covered Pd nanostructures exhibited excellent catalytic property in terms of semihydrogenation of alkynes.

  20. Hydrogen bonding and proton transfer to ruthenium hydride complex CpRuH(dppe): metal and hydride dichotomy.

    Science.gov (United States)

    Silantyev, Gleb A; Filippov, Oleg A; Tolstoy, Peter M; Belkova, Natalia V; Epstein, Lina M; Weisz, Klaus; Shubina, Elena S

    2013-02-18

    The combination of variable temperature (190-297 K) IR and NMR spectroscopy studies with quantum-chemical calculations at the DFT/B3PW91 and AIM level had the aim to determine the mechanism of proton transfer to CpRuH(dppe) (1, dppe = Ph(2)P(CH(2))(2)PPh(2)) and the structures of intermediates. Dihydrogen bond (DHB) formation was established in the case of interaction with weak proton donors like CF(3)CH(2)OH. Low-temperature protonation (at about 200 K) by stronger proton donors leads via DHB complex to the cationic nonclassical complex [CpRu(η(2)-H(2))(dppe)](+) (2). Thermodynamic parameters of DHB formation (for CF(3)CH(2)OH: ΔH°(HB) = -4.9 ± 0.2 kcal·mol(-1), ΔS°(HB) = -17.8 ± 0.7 cal·mol(-1)·K(-1)) and proton transfer (for (CF(3))(2)CHOH: ΔH°(PT) = -5.2 ± 0.3 kcal·mol(-1), ΔS°(PT) = -23 ± 1 cal·mol(-1)·K(-1)) were determined. Above 240 K 2 transforms into trans-[CpRu(H)(2)(dppe)](+) (3) yielding a mixture of 2 and 3 in 1:2 ratio. Kinetic analysis and activation parameters for the "[Ru(η(2)-H(2))](+) → trans-[Ru(H)(2)](+)" transformation indicate reversibility of this process in contrast to irreversible intramolecular isomerization of the Cp* analogue. Calculations show that the driving force of this process is greater stability (by 1.5 kcal·mol(-1) in ΔE scale) of the dihydride cation in comparison with the dihydrogen complex. The calculations of the potential energy profile indicate the low barrier for deprotonation of 2 suggesting that the formation of trans-[CpRu(H)(2)(dppe)](+) proceeds via deprotonation of [Ru(η(2)-H(2))](+) to DHB complex, formation of hydrogen bond with Ru atom and subsequent proton transfer to the metal site.

  1. Preparation of Sm–Ru bimetallic alloy films on Ru(0001) surface by vapour-deposition and annealing

    Indian Academy of Sciences (India)

    G Ranga Rao; H Nozoye

    2001-12-01

    Sm–Ru intermetallic surface alloy films were prepared by vacuum deposition and annealing of rare earth Sm on single crystal Ru(0001) surface. The Ru 3 and Sm 3 core level spectra clearly show the formation of surface alloy layers. XPS measurements on surface alloy film revealed an induced peak in the Ru3 region at lower binding energy by 1 eV compared to the bulk Ru (elemental) suggesting an electronic effect of alloying and Sm–Ru bond formation. The Sm 35/2 photoemission peak of Sm film consists of strong features characteristic of Sm(II) with electron configuration 46 (5\\ 6)2 and Sm(III) with electron configuration 46 (5\\ 6)3. It is observed that the Sm(II) feature decreases in intensity upon alloy formation with surface Ru atoms. Oxidation of these films with carbon monoxide indicates alloy breakdown due to the oxidation of Sm atoms selectively. Alloy oxidation also shows a clear shift of Sm 35/2 feature.

  2. Submonolayered Ru Deposited on Ultrathin Pd Nanosheets used for Enhanced Catalytic Applications.

    Science.gov (United States)

    Zhang, Zhicheng; Liu, Ye; Chen, Bo; Gong, Yue; Gu, Lin; Fan, Zhanxi; Yang, Nailiang; Lai, Zhuangchai; Chen, Ye; Wang, Jie; Huang, Ying; Sindoro, Melinda; Niu, Wenxin; Li, Bing; Zong, Yun; Yang, Yanhui; Huang, Xiao; Huo, Fengwei; Huang, Wei; Zhang, Hua

    2016-12-01

    Ultrathin Pd nanosheets (NSs) coated with submonolayered Ru, referred to as Pd@Ru NSs, are synthesized via a seed-mediated growth method. The underpotential deposition can be the driving force for the formation of Pd@Ru NSs. The Pd@Ru NSs exhibit superior catalytic properties in the reduction of 4-nitrophenol and the semihydrogenation of 1-octyne, compared to the pure Pd NSs and Ru NSs.

  3. Methanol Electrooxidation on Smooth Platinum Modified with Ru: the Influence of Ru Coverage and Potentials on Oxidative Current and Products

    Institute of Scientific and Technical Information of China (English)

    WANG, Hong-Sen

    2003-01-01

    Methanol oxidation on smooth Pt electrode modified with different coverage of Ru was studied using cyclic voltammetry and potential step combined with differential electrochemical mass spectroscopy. The current efficiency of formed CO2 was calculated from faraday current and ion current of m/z = 44. The results show that Ru modified Pt electrode with the coverage of ca. 0.3 has the highest catalytic activity for methanol electrooxidation, I.e. Faraday current and the current efficiency of CO2at the low potentials reach to the maximum. In addition, Ru loses its co-catalytic properties at the high potentials.

  4. Surface studies by low energy ion beams: Cu/Ru(0001) and Cu/O/Ru(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y.G.; O`Connor, D.J.; MacDonald, R.J. [Newcastle Univ., NSW (Australia). Dept. of Physics; Wandelt, H. [Institut fur Physikalische und Theoretische Chemie der Universitat Bonn, Bonn (Germany).; Zee, H. van [Eindhoven University of Technology, Eindhoven (Netherlands) Dept. of Physics

    1993-12-31

    The surface structure of Cu on Ru(OOO1) has been studied by low energy Li{sup +} ion scattering. It was found that Cu forms pseudomorphic islands for two layers. The effects of Cu on an O-precovered RU(OOO1) surface has also been investigated using keV He{sup +} ions. The results show that during the deposition of Cu, O is displaced from the Ru surface and migrated onto the top of the surface of the growing overlayer. The floated out O has been tested, showing a disordered overlayer. 5 refs., 3 figs.

  5. Partial phase diagram of Pd-Ag-Ru-Gd quaternary system

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd(Gd<25% atom fraction) quaternary system has been studied by means of X-ray diffraction analysis, differential thermal analysis, electron probe microanalysis and optical microscopy.The 700℃ isothermal sections of the Ag-Pd-5Ru-Gd, Ag-Pd-20Ru-Gd and Ag-Pd-50Ru-Gd (Gd≤25%atom fraction) phase diagrams were determined respectively. And the 700℃ isothermal section of the PdAg-Ru-Gd (Gd≤25% atom fraction) quaternary system phase diagram was finally irferred. The section consists of four single-phase regions: solid solution Pd(Ag), (Ru), Pd3Gd and Ag51 Gd14; five two-phase regions: Pd(Ag) + (Ru), Pd(Ag) + Ag51 Gd14 , (Ru) + Ag51 Gd14 , Pd(Ag) + Pd3Gd and (Ru) +Pd3Gd; three three-phase regions: Pd(Ag) + Pd3Gd+ (Ru), Pd(Ag) + Ag51Gd14 + (Ru) and (Ru) +Ag51Gd14 + Pd3Gd; one four-phase region Pd(Ag) + (Ru) + Ag51Gd14 + Pd3Gd. No new quaternary intermetallic phase is found.

  6. Uranium ferromagnet with negligible magnetocrystalline anisotropy: U4Ru7Ge6

    Science.gov (United States)

    Vališka, Michal; Diviš, Martin; Sechovský, Vladimír

    2017-02-01

    Strong magnetocrystalline anisotropy (MA) is a well-known property of uranium compounds. The almost isotropic ferromagnetism in U4Ru7Ge6 reported in this paper represents a striking exception. We present results for magnetization, ac susceptibility, thermal expansion, specific heat, and electrical resistivity measurements performed on a U4Ru7Ge6 single crystal at various temperatures and magnetic fields; we discuss the results in relation to first-principles electronic structure calculations. U4Ru7Ge6 behaves as an itinerant 5 f -electron ferromagnet (TC=10.7 K , μS=0.85 μB/f .u . at 1.9 K ). The ground-state easy magnetization direction is along the [111] axis of the cubic lattice. The anisotropy field μ0Ha along the [001] direction is only about 0.3 T , which is at least three orders of magnitude smaller than for other U ferromagnets. At Tr=5.9 K the easy magnetization direction changes to [001], and remains [001] up to TC. This transition is due to a change in magnetic symmetry, and is quite apparent in the low-field magnetization, ac susceptibility, and thermal expansion data, whereas only weak anomalies are observed at Tr in the temperature dependence of the specific heat and electrical resistivity. The magnetoelastic interaction induces a rhombohedral (tetragonal) distortion of the paramagnetic cubic crystal lattice in the case of the [111] ([001]) easy magnetization direction. The rhombohedral distortion is connected with two crystallographically inequivalent U sites. Our density functional theory calculations, including spin-orbit interaction (SOI) of the U 5 f electrons, also produces two inequivalent U sites, because SOI leads to a reduction of the symmetry of the former cubic structure. The calculated ground state is in agreement with the experimentally observed [111] easy magnetization direction. The first excited state has moments along the [001] direction, which agrees with the moment orientation for T >Tr . The energy of the first excited state is

  7. Annealing of RuO 2 and Ru Bottom Electrodes and Its Effects on the Electrical Properties of (Ba,Sr)TiO 3 Thin Films

    Science.gov (United States)

    Ahn, Joon-Hyung; Choi, Won-Youl; Lee, Won-Jae; Kim, Ho-Gi

    1998-01-01

    Crystalline structures and surface morphologies of annealed RuO2 and Ru thin films were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The annealing was performed in oxygen and argon ambient and high vacuum in the temperature range of 400 800° C. In oxygen ambient annealing, the surface morphology was drastically changed due to the evaporation of ruthenium dioxides in the form of RuO3 and RuO4. Annealed RuO2 thin film in vacuum was reduced to the Ru metal phase. The actual variation of RuO2 bottom electrodes during the deposition of (Ba,Sr)TiO3 (BST) thin films and the effects of the thermal stability of bottom electrodes on electrical properties of BST thin films deposited on RuO2/SiO2/Si were also investigated.

  8. Study of Ru{sub 2}VGe and Ru{sub 2}VSb: High-spin polarized and half-metallic Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, Idris Hamid; Gupta, Dinesh C. [Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior – 474011 (India)

    2015-06-24

    Electronic and magnetic properties of Ru{sub 2}VGe and Ru{sub 2}VSb have been investigated by ab-initio. The optimized equilibrium lattice parameters were found to be 6.032 Å for Ru{sub 2}VGe and 6.272 Å for Ru{sub 2}VSb. Both the materials have ferromagnetic ground states and V mainly contributes to the magnetic properties in these materials. The highly spin-polarized half-metallic materials have integral magnetic moments of 1.0 µ{sub B} for Ru{sub 2}VGe and 2.0 µ{sub B} for Ru{sub 2}VSb with an energy gap of 0.095 eV for Ru2VGe and 0.186 eV for Ru{sub 2}VSb in the spin-down channel.

  9. Beta decay of Tc-111 to Ru-111

    NARCIS (Netherlands)

    Pfeiffer, B; Lhersonneau, G; Dendooven, P; Honkanen, A; Huhta, M; Klockl, [No Value; Oinonen, M; Penttila, H; Persson, B.L.; Perajarvi, K; Wang, JC; Kratz, KL; Aysto, J

    1998-01-01

    The beta-decay of the very neutron-rich Tc-111 nucleus has been observed. A partial decay scheme of Ru-111 is presented, complementing the high-spin levels earlier reported in spontaneous fission work.

  10. β-delayed proton decay of 89Ru

    Institute of Scientific and Technical Information of China (English)

    李占奎; 徐树威; 于涌; 谢元祥; 王春芳; 邢建萍; 潘强岩; 胡青元; 李世红; 陈红艳; 张天梅

    2000-01-01

    89Ru was synthesized in the reaction of 58Ni (36Ar, 2p3n) on the basis of a "p-γ" coincidence measurement by using a He-jet tape transport system, and its p-delayed proton emission with a half-life of (1.1 ±0.2) s was investigated. The p-delayed proton spectrum of 89Ru populating the low-lying states in 88Mo was obtained, and the final state proton branching ratios to the low-lying 2+ and 4 + states in88Mo were estimated to be 100:6. Based on the statistical model calculations, the ground state spin of 89Ru was preliminarily assigned to be 5/2+ or 7/2±, and the mass excess of 89Ru was deduced to be -59.5 MeV.

  11. Dissociation of CH4 on Ni(111) and Ru(0001)

    DEFF Research Database (Denmark)

    Egeberg, Rasmus; Ullmann, S.; Alstrup, I.

    2002-01-01

    to clarify to what extent a similar effect is present in these systems. The apparent activation energies found were 74 +/- 10 and 51 +/- 6 kJ/mol on Ni(1 1 1) and Ru(0 0 0 1) respectively. On neither Ru(0 0 0 1) nor Ni(1 1 1) did we observe a significant decrease of the overall sticking coefficient when...... the terraces, Finally we have observed a large promotion of the sticking probability of CH4 on Ru(0 0 0 1) by increasing the surface temperature at a fixed gas temperature thus lending support to a mechanism where the dissociation of methane takes place over Ru atoms displaced normal to the surface....

  12. β-delayed proton decay of 89Ru

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    89Ru was synthesized in the reaction of 58Ni (36Ar, 2p3n) on the basis of a "p-γ" coincidence measurement by using a He-jet tape transport system, and its β-delayed proton emission with a half-life of (1.1±0.2) s was investigated. The β-delayed proton spectrum of 89Ru populating the low-lying states in 88Mo was obtained, and the final state proton branching ratios to the low-lying 2+ and 4+ states in 88Mo were estimated to be 100:6. Based on the statistical model calculations, the ground state spin of 89Ru was preliminarily assigned to be 5/2+ or 7/2±, and the mass excess of 89Ru was deduced to be -59.5 MeV.

  13. Isospin Distribution of Fragments in Reaction 96Ru+96Ru, 96Ru+96Zr, 96Zr+96Ru, and 96Zr+96Zr at Beam Energy 400 AMeV

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The isospin distribution of particles and fragments in collisions 96Ru+96Ru, 96Ru+96Zr, 96Zr+96Ru, and 96Zr+96Zr at beam energy 400 AMeV is studied with isospin dependent QMD model. We find the rapidity distribution of difference between neutron-proton number in neutron rich nucleus-nucleus collisions at intermediate energies is sensitive to the isospin dependent part of nuclear potential. The study of the N/Z ratio of nucleons, light charged particles (LCP) and intermediate mass fragments (IMF) shows that the isospin dependent part of nuclear potential drives IMF to be more isospin symmetric and emitted nucleons to be more neutron rich. We also study the time evolution of the isospin distribution

  14. Alkali promotion of N-2 dissociation over Ru(0001)

    DEFF Research Database (Denmark)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Using self-consistent density functional calculations, we show that adsorbed Na and Cs lower the barrier for dissociation of N2 on Ru(0001). Since N2 dissociation is a crucial step in the ammonia synthesis reaction, we explain in this way the experimental observation that alkali metals promote th...... the ammonia synthesis reaction over Ru catalysts. We also show that the origin of this effect is predominantly a direct electrostatic attraction between the adsorbed alkali atoms and the dissociating molecule....

  15. Low-temperature properties of Ce(Ru 1- xM x) 2Ge 2, M  Fe, Au

    Science.gov (United States)

    Fontes, M. B.; Elmassalami, M.; Aliaga-Guerra, D.; Giordanengo, B.; Bud'ko, S. L.; Guimaraes, A. P.; Gavilano, J. L.; Baggio-Saitovitch, E. M.

    1995-02-01

    We have performed measurements of electrical resistivity, AC susceptibility, magnetization, Mössbauer effect and NMR on the series of intermetallic compounds Ce(Ru 1- xM x) 2Ge 2, M  Fe, Au for 0 ⩽ x ⩽ 0.1. The parent compound CeRu 2Ge 2 orders ferromagnetically below 7.5 K, with f-electrons showing only a small mass-enhancement at low temperatures. However, its crystal structure and Fermi surface are closely related to the heavy-electron superconductor CeRu 2Si 2. Analysis of X-ray diffraction patterns confirmed the structure to be of thCr 2Si 2-type, with no foreign phases detected. The results of our Mössbauer studies indicate that Fe goes into the Ru sites with no magnetic moment. NMR signals were observed in the Fe-doped samples with quadrupolar interaction that can be related to 73Ge nucleus ( I = 9/2).

  16. Structures and magnetic properties of double perovskites A sub 2 LnMO sub 6 and 6H-perovskites Ba sub 3 LnRu sub 2 O sub 9 (A=Sr, Ba; Ln=Y, lanthanides; M=Nb, Ta, Ru)

    CERN Document Server

    Hinatsu, Y

    2003-01-01

    This account describes the synthesis, crystal structures and magnetic properties of double perovskites A sub 2 LnMO sub 6 and 6H-perovskites Ba sub 3 LnRu sub 2 O sub 9 (A=Sr, Ba; Ln=Y, lanthanides; M=Nb, Ta, Ru). The double perovskites A sub 2 LnMO sub 6 have two kinds of cations, Ln and M, in the B site of the perovskite ABO sub 3. These cations adopt the alternative ordered arrangement. Measurements of the magnetic susceptibility, specific heat, and powder neutron diffraction showed that all of the A sub 2 LnRuO sub 6 compounds exhibited an antiferromagnetic transition at low temperatures and a complex temperature dependence of the magnetic susceptibility below their transition temperatures. In these compounds, the magnetic interaction between the Ln (4f electrons) and Ru (4d electrons) ions via the Ln-O-Ru pathway contributes greatly to their magnetic cooperative phenomena. The structural and magnetic studies for the 6H-perovskites Ba sub 3 LnRu sub 2 O sub 9 show that the Ln cations occupy the corner-sha...

  17. Enantioselective Michael reaction catalyzed by well-defined chiral ru amido complexes: isolation and characterization of the catalyst intermediate, ru malonato complex having a metal-carbon bond.

    Science.gov (United States)

    Watanabe, Masahito; Murata, Kunihiko; Ikariya, Takao

    2003-06-25

    Chiral Ru amido complexes promote asymmetric Michael addition of malonates to cyclic enones, leading to Michael adducts with excellent ee's, in which the chiral Ru amido complexes react with malonates to give isolable catalyst intermediates, chiral Ru malonato complexes bearing a metal bound C-nucleophile.

  18. Enhancement of Solar Fuel Production Schemes by Using a Ru,Rh,Ru Supramolecular Photocatalyst Containing Hydroxide Labile Ligands.

    Science.gov (United States)

    Rogers, Hannah Mallalieu; Arachchige, Shamindri M; Brewer, Karen J

    2015-11-16

    Polyazine-bridged Ru(II)Rh(III)Ru(II) complexes with two halide ligands, Cl(-) or Br(-), bound to the catalytically active Rh center are efficient single-component photocatalysts for H2O reduction to H2 fuel, with the coordination environment on Rh impacting photocatalysis. Herein reported is a new, halide-free Ru(II)Rh(III)Ru(II) photocatalyst with OH(-) ligands bound to Rh, further enhancing the photocatalytic reactivity of the structural motif. H2 production experiments using the photocatalyst bearing OH(-) ligands at Rh relative to the analogues bearing halides at Rh in solvents of varying polarity (DMF, CH3CN, and H2O) suggest that ion pairing with halides deactivates photocatalyst function, representing an exciting phenomenon to exploit in the development of catalysts for solar H2 production schemes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Kinetics of reduction of a RuO2(110) film on Ru by atomic hydrogen

    NARCIS (Netherlands)

    Ugur, D.; Storm, A.J.; Verberk, R.; Brouwer, J.C.; Sloof, W.G.

    2013-01-01

    The kinetics and the mechanism of reduction of a RuO2(110) film, grown thermally on a Ru(0001) surface, has been studied in the temperature range of 60-200 °C by using an atomic hydrogen flux of 2 × 1019 at. H m-2 s-1. The reduction kinetics is dominated by the creation of oxygen vacancies at the su

  20. Enhancement of perpendicular magnetic anisotropy and coercivity in ultrathin Ru/Co/Ru films through the buffer layer engineering

    Science.gov (United States)

    Kolesnikov, Alexander G.; Stebliy, Maxim E.; Ognev, Alexey V.; Samardak, Alexander S.; Fedorets, Aleksandr N.; Plotnikov, Vladimir S.; Han, Xiufeng; Chebotkevich, Ludmila A.

    2016-10-01

    We present results on a study of the interplay between microstructure and the magnetic properties of ultrathin Ru/Co/Ru films with perpendicular magnetic anisotropy (PMA). To induce PMA in the Co layer, we experimentally determined thicknesses of the buffer and capping layers of Ru. The maximum value of PMA was observed for the Co thickness of 0.9 nm with the 3 nm thick capping layer. The effective anisotropy field (H eff) and coercive force (H c) of the Co layer are very sensitive to the Ru buffer layer thickness (t b). The values of H eff and H c increase approximately by two and ten times, correspondingly, when t b changes from 6 to 20 nm, owing to an increase in volume fraction of the crystalline phase as a result of the grains’ growth. PMA is found to be mainly enhanced by elastic strains induced by the lattice mismatch on the Ru/Co and Co/Ru interfaces, leading to the deformation of the Co lattice. The surface impact is determined to be less than 10% of the magneto-elastic contribution to the effective anisotropy. Observation of the magnetic domain structure by means of polar Kerr microscopy reveals that out-of-plane magnetization reversal occurs through the nucleation, growth, and annihilation of domains, where the average size drastically rises with the increasing t b.

  1. Structure and Reactions of Carbon and Hydrogen on Ru(0001): A Scanning Tunneling Microscopy Study

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, Tomoko K.; Mugarza, Aitor; Cerda, Jorge; Salmeron, Miquel

    2008-09-09

    The interaction between carbon and hydrogen atoms on a Ru(0001) surface was studied using scanning tunneling microscopy (STM), Density Functional Theory (DFT) and STM image calculations. Formation of CH species by reaction between adsorbed H and C was observed to occur readily at 100 K. When the coverage of H increased new complexes of the form CH+nH (n = 1, 2 and 3) were observed. These complexes, never observed before, might be precursors for further hydrogenation reactions. DFT analysis reveals that a considerable energy barrier exists for the CH+H {yields} CH{sub 2} reaction.

  2. Study on Chemisorption and Desorption of Hydrogen and Nitrogen on Ru-based Ammonia Synthesis Catalyst

    Institute of Scientific and Technical Information of China (English)

    祝一锋; 李小年

    2003-01-01

    The effects of promoters K,Ba,Sm,on the chemisorption and desorption of hydrogen and nitrogen,dispersion of metallic Ru and catalytic activity of active carbon(AC) supported ruthenium catalyst for ammonia synthesis have been studied by means of pulse chromatography,temperature-programmed desorption,and activity test,Promoters K,Ba and Sm increased the activity of Ru/AC catalysts for ammonia synthesis significantly,and particularly,potassium exhibited the best promotion on the activity because of the strong electronic donation to metallic Ru.Much higher activity can be obtained for Ru/AC catalyst with binary or triple promoters.The activity of Ru/AC catalyst is dependent on the adsorption of hydrogen and nitrogen.The high activity of catalyst could be ascribed to strong dissociation of nitrogen on the catalyst surface.Strong adsorption of hydrogen would inhibit the adsorption of nitrogen,resulted in decrease of the catalytic activity.Ru/AC catalyst promoted by Sm2O3 shows the best dispersion of metallic Ru,since the partly reduced SmO2 on the surface modifies the morphology of active sites and favors the dispersion of metallic Ru.The activity of Ru/AC catalysts is in accordance to the corresponding amount of nitrogen chemisorption and the desorption activation enery of nitrogen.The desorption activation energy for nitrogen decreases in the order of Ru>Ru-Ba>Ru-Sm>Ru-Bs-Sm>Ru-K>Ru-K-Bm>Ru-K-Ba>Ru-K-Ba-Sm,just opposite to the order or catalytic activity,suggesting that the ammonia synthesis over Ru-based catalyst is controlled by the step of dissociation of nitrogen.

  3. Face to phase with RU Lupi

    CERN Document Server

    Gahm, Gösta F; Walter, Frederick M; Petrov, Peter P; Herczeg, Gregory J

    2013-01-01

    We present new results on the classical T Tauri star RU Lupi based on three observing runs collecting high-resolution spectra, complementary NIR spectra, multicolour photometric data, and X-ray observations. The photospheric absorption lines are weakened. This veiling becomes extremely strong on occasion, and we show that this effect is due to narrow emission lines that fill in the photospheric lines. The blue-shifted wings in the optical emission lines of He I, attributed to a stellar wind, are remarkably stable in equivalent width. In contrast, the red-shifted wings change dramatically in strength depending on rotational phase. From the pattern of variability we infer that these wings originate in accreting gas close to the star, and that the accretion funnels are bent and trail the hot spot. Forbidden emission lines are very stable over the entire observing period and originate in the disk wind. A system of narrow blue-shifted absorption features seen in lines of Ca II and Na I can be traced to a disk wind...

  4. A redox-active porous coordination network film based on a Ru complex as a building block on an ITO electrode.

    Science.gov (United States)

    Shinomiya, Takuya; Ozawa, Hiroaki; Mutoh, Yuichiro; Haga, Masa-Aki

    2013-12-01

    The combination of self-assembled monolayer (SAM) and layer-by-layer (LbL) growth methods for the construction of a surface porous film has the potential to incorporate a wide range of chemical functionalities on a solid surface. A novel redox-active Ru complex with 2,6-bis(N-pyridylbenzimidazolyl)-pyridine ligands (Ru complex 1), in which four peripheral pyridine groups act as coordination sites, was used as a building block for a porous coordination network film. By using (4-pyridyl)phenylphosphonic acid as a SAM primer layer on an ITO surface, the Ru complex 1 was immobilized by the successive reaction of PdCl2 on the ITO electrode in the LbL growth method. Multilayer growth was monitored by UV-vis spectra and cyclic voltammetry, in which the linear increases of both absorbance and the peak current were observed. This result indicated that the regular accumulation of Ru complex 1 onto the ITO surface took place. The permselectivity of the present porous coordination network structure was examined using redox-active molecular probes with different sizes and charges such as ferrocene, trimethylaminomethylferrocene, the Os bis(2,6-bis(N-methylbenzimidazolyl)-pyridine) complex, and tetrathiofulvarene (TTF). With the Os complex and cationic ferrocene, only the catalytic peak was observed as a prewave of the adsorbed Ru(II/III) peak at +0.73 V. On the other hand, the oxidation peak of ferrocene was observed around 0 V vs. Fc(+)/Fc even for nine-layered films in addition to the adsorbed Ru(II/III) peak. From these results, not only molecular size but also electrostatic interaction plays an important role in the permeation into the Ru complex 1 porous network film.

  5. Standard enthalpies of formation of selected Ru{sub 2}YZ Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ming, E-mail: myin1@hawk.iit.edu; Nash, Philip

    2015-06-15

    Highlights: • Standard enthalpies of formation of Ru{sub 2}YZ were measured using a drop calorimeter. • Result of L2{sub 1} structured compounds agrees with first principles data. • Lattice parameters and related phase relationships were consistent with literature data. • Ru{sub 2}HfSn, Ru{sub 2}TiSn, Ru{sub 2}VGa, Ru{sub 2}VSi, Ru{sub 2}VSn of L2{sub 1} structure were reported for the first time. - Abstract: The standard enthalpies of formation of selected ternary Ru-based Heusler compounds Ru{sub 2}YZ (Y = Fe, Hf, Mn, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) were measured using high temperature direct reaction calorimetry. The measured enthalpies of formation (in kJ/mole of atoms) of the Heusler compounds are, Ru{sub 2}FeGe (−19.7 ± 3.3); Ru{sub 2}HfSn (−24.9 ± 3.6); Ru{sub 2}MnSi (−46.0 ± 2.6); Ru{sub 2}MnGe (−29.7 ± 1.0); Ru{sub 2}MnSn (−20.6 ± 2.4); Ru{sub 2}TiSi (−94.9 ± 4.0); Ru{sub 2}TiGe (−79.1 ± 3.2); Ru{sub 2}TiSn (−60.6 ± 1.8); Ru{sub 2}VSi (−55.9 ± 1.7);for the B2-structured compounds, Ru{sub 2}FeSi (−28.5 ± 0.8); Ru{sub 2}HfAl (−70.8 ± 1.9); Ru{sub 2}MnAl (−32.3 ± 1.9); Ru{sub 2}MnGa (−25.3 ± 3.0); Ru{sub 2}TiAl (−62.7 ± 3.5); Ru{sub 2}VAl (−30.9 ± 1.6); Ru{sub 2}ZrAl (−64.5 ± 1.5). Values were compared with those from published first principles calculations and the OQMD (Open Quantum Materials Database). Lattice parameters of these compounds were determined using X-ray diffraction analysis (XRD). Microstructures were identified using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS)

  6. Design, synthesis, DNA-binding affinity, cytotoxicity, apoptosis, and cell cycle arrest of Ru(II) polypyridyl complexes.

    Science.gov (United States)

    Venkat Reddy, Putta; Reddy, Mallepally Rajender; Avudoddi, Srishailam; Praveen Kumar, Yata; Nagamani, Chintakuntla; Deepika, Nancherla; Nagasuryaprasad, K; Singh, Surya Satyanarayana; Satyanarayana, Sirasani

    2015-09-15

    A novel polypyridyl ligand CNPFIP (CNPFIP=2-(5(4-chloro-2-nitrophenyl)furan-2-yl)-1H-imidazo[4,5f][1,10]phenanthroline) and its mononuclear Ru(II) polypyridyl complexes of [Ru(phen)2CNPFIP](2+)(1) (phen=1,10-phenanthroline), [Ru(bpy)2CNPFIP](2+)(2) (bpy=2,2'-bipyridine), and [Ru(dmb)2CNPFIP](2+)(3) (dmb=4,4'-dimethyl-2,2'-bipyridine) have been synthesized successfully and characterized thoroughly by elemental analysis, UV/Vis, IR, NMR, and ESI-MS. The interaction of the Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by absorption titration, fluorescence, viscosity measurements. The experimental results suggest that three complexes bind to CT-DNA through an intercalative mode and the DNA-binding affinity of complex 1 is greater than that of complexes 2 and 3. The photocleavage of plasmid pBR322 DNA by ruthenium complexes 1, 2, and 3 was investigated. We have also tested three complexes for their antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. The in vitro cytotoxicity of these complexes was evaluated by MTT assay, and complex 1 shows higher cytotoxicity than 2 and 3 on HeLa cells. The induced apoptosis and cell cycle arrest of HeLa cells were investigated by flow cytometry for 24h. The molecular docking of ruthenium complexes 1, 2, and 3 with the active site pocket residues of human DNA TOP1 was performed using LibDock.

  7. Preparation and characterization of ultrathin [Ru(CO)3Cl2]2 and [BMIM][Tf2N] films on Al2O3/NiAl(110) under UHV conditions.

    Science.gov (United States)

    Sobota, Marek; Schernich, Stefan; Schulz, Hannes; Hieringer, Wolfgang; Paape, Natalia; Wasserscheid, Peter; Görling, Andreas; Laurin, Mathias; Libuda, Jörg

    2012-08-14

    Towards a better understanding of the interface chemistry of ionic liquid (IL) thin film catalytic systems we have applied a rigorous surface science model approach. For the first time, a model homogeneous catalyst has been prepared under ultrahigh vacuum conditions. The catalyst, di-μ-chlorobis(chlorotricarbonylruthenium) [Ru(CO)(3)Cl(2)](2), and the solvent, the IL 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [BMIM][Tf(2)N], have been deposited by physical vapor deposition onto an alumina model support [Al(2)O(3)/NiAl(110)]. First, the interaction between thin films of [Ru(CO)(3)Cl(2)](2) and the support is investigated. Then, the ruthenium complex is co-deposited with the IL and the influence of the solvent on the catalyst is discussed. D(2)O, which is a model reactant, is further added. Growth, surface interactions, and mutual interactions in the thin films are studied with IRAS in combination with density functional (DFT) calculations. At 105 K, molecular adsorption of [Ru(CO)(3)Cl(2)](2) is observed on Al(2)O(3)/NiAl(110). The IRAS spectra of the binary [Ru(CO)(3)Cl(2)](2) + [BMIM][Tf(2)N] and ternary [Ru(CO)(3)Cl(2)](2) + [BMIM][Tf(2)N] + D(2)O show every characteristic band of the individual components. Above 223 K, partial decomposition of the ruthenium complex leads to species of molecular nature attributed to Ru(CO) and Ru(CO)(2) surface species. Formation of metallic ruthenium clusters occurs above 300 K and the model catalyst decomposes further at higher temperatures. Neither the presence of the IL nor of D(2)O prevents this partial decomposition of [Ru(CO)(3)Cl(2)](2) on alumina.

  8. Ferromagnetic resonance study of interface coupling for spin waves in narrow NiFe/Ru/NiFe multilayer nanowires

    Science.gov (United States)

    Lupo, P.; Haghshenasfard, Z.; Cottam, M. G.; Adeyeye, A. O.

    2016-12-01

    A systematic investigation is presented for the magnetization dynamics in trilayer nanowires, consisting of two permalloy (Ni80Fe20 ) layers separated by a nonmagnetic Ru spacer layer. The width of the wires ranges from 90 to 190 nm. By varying the Ru thickness between 0.7 and 2.0 nm, the interlayer coupling can be effectively controlled, modifying the corresponding magnetic ground state and the spin-wave dynamics. By contrast with previous work on coupled trilayer nanowires with larger widths (270 nm and more), the focus here is on nanowire arrays where the strong shape anisotropy competes with the Ruderman-Kittel-Kasuya-Yosida interactions and biquadratic exchange interactions across the Ru interface, as well as dipolar interactions and Zeeman energy. As a result, the spin-wave spectrum is found to be drastically modified. Ferromagnetic resonance and hysteresis loop measurements are reported over a wide range of applied magnetic fields, showing that the overall magnetization alignment between the permalloy layers may be parallel, antiparallel, or in a spin-flop state, depending on the overall interlayer coupling. The experimental results for different stripe widths are successfully analyzed using a microscopic dipole-dipole theory and micromagnetic simulations.

  9. Structure, synthesis, and thermal properties of trans-[Ru(NO)(NH{sub 3}){sub 4}(SO{sub 4})]NO{sub 3}.H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Makhinya, A.N.; Il' in, M.A.; Plyusnin, P.E. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Nikolaev Inst. of Inorganic Chemistry; Novosibirsk State Univ. (Russian Federation); Baidina, I.A.; Alferova, N.I.; Pishchur, D.P. [Russian Academy of Sciences, Novosibirsk (Russian Federation). Nikolaev Inst. of Inorganic Chemistry

    2014-07-01

    In treatment of trans-[Ru(NO)(NH{sub 3}){sub 4}(OH)]Cl{sub 2} with concentrated sulfuric acid on heating trans-[Ru(NO)(NH{sub 3}){sub 4}(SO{sub 4})](HSO{sub 4}).H{sub 2}O (I) is obtained with a yield close to quantitative. In the interaction of the saturated solution of I with a saturated NaNO{sub 3} solution a trans-[Ru(NO)(NH{sub 3}){sub 4}(SO{sub 4})]NO{sub 3}.H{sub 2}O (II) precipitate forms whose structure is determined by single crystal XRD: space group P2{sub 1}2{sub 1}2{sub 1}, a = 6.8406(3) Aa, b = 12.6581(5) Aa, c = 13.3291(5) Aa. A monodentately coordinated sulfate ion is in the trans-position to the nitroso group. Compound II is characterized by IR spectroscopy, powder XRD, and diffuse reflectance spectroscopy. The process of its thermolysis is studied; by differential scanning calorimetry the thermal effect of the dehydration reaction occurring on heating to 120 C (ΔH = 58.9 ± 1.5 kJ/mol) is estimated. The final product of the thermolysis of II is a mixture of Ru and RuO{sub 2}.

  10. Large exchange bias effect in LaCr{sub 0.9}Ru{sub 0.1}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Babusona; Dalal, Biswajit; De, S.K., E-mail: msskd@iacs.res.in

    2016-11-01

    The incorporation of tetravalent Ru (10%) into antiferromagnetic spin structure of LaCrO{sub 3} leads to mixed valence states of Cr (Cr{sup 2+} and Cr{sup 3+}). Highly delocalized 4d orbital of Ru induces prominent ferromagnetic (FM) component in antiferromagnetic (AFM) matrix of parent compound. The complex magnetic interaction across the interface of FM and AFM regions gives rise to large exchange bias field (H{sub EB}) of about 10 kOe. The inverse and normal magnetocaloric effect for magnetic field up to 50 kOe coexists in a single material due to multiple magnetic phase transitions with temperature. - Graphical abstract: Highly delocalized 4d orbital of Ru induces prominent ferromagnetic (FM) component in antiferromagnetic (AFM) matrix of parent compound. - Highlights: • Incorporation of Ru{sup 4+} into the antiferromagnetic spin structure of LaCrO{sub 3}. • Large exchange bias has been observed for 10% Ru doped LaCrO{sub 3}. • Coexistence of normal and inverse magnetocaloric effect.

  11. Low-temperature properties of the S =1/2 spin system Yb3Ru4Al12 with a distorted kagome lattice structure

    Science.gov (United States)

    Nakamura, S.; Toyoshima, S.; Kabeya, N.; Katoh, K.; Nojima, T.; Ochiai, A.

    2015-06-01

    We have synthesized single crystals of ternary intermetallic Yb3Ru4Al12 with a distorted kagome lattice structure, and investigated the low-temperature resistivity, specific heat, magnetization, and magnetic phase transitions. Yb3Ru4Al12 is the first 4 f system that has a Gd3Ru4Al12 -type crystal structure where antiferromagnetic interaction acts on the spin. The crystal electric field (CEF) ground state of this compound is determined as a well isolated twofold degenerate state that is subjected to a strong easy-plane-type magnetic anisotropy. In the present study, the spin system of Yb3Ru4Al12 is regarded as an AFM X Y model of S =1 /2 . This compound undergoes successive magnetic phase transitions at 1.5 and 1.6 K, and the resistivity exhibits T2 behavior below 1 K. The ratio of the coefficient of the T2 term in the resistivity A , and that of the electronic specific heat coefficient γ0, deviates from the Kadowaki-Woods (KW) law. The successive phase transitions and low-temperature properties of Yb3Ru4Al12 where geometrical frustration and heavy fermion behavior occur are discussed.

  12. Photocatalytic hydrogen evolution from CdS-ZnO-CdO systems under visible light irradiation: Effect of thermal treatment and presence of Pt and Ru cocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, R.M.; del Valle, F.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, Cantoblanco, 28049 Madrid (Spain)

    2008-08-15

    A CdS-CdO-ZnO mixture annealed at different temperatures and loaded with Ru or Pt cocatalysts has been investigated in the production of hydrogen from aqueous solutions containing SO{sub 3}{sup 2-}+S{sup 2-} as sacrificial reagents under visible light. The physicochemical characterization of the CdS-CdO-ZnO catalyst revealed significant changes in the crystalline structure and visible light absorption capacity as a result of thermal treatments. Catalytic activity was found to be strongly dependent on physicochemical changes associated with thermal annealing. Hydrogen evolution over the CdS-CdO-ZnO catalyst was enhanced in the sample annealed at 773 K by the better contact between the CdS and CdO-ZnO phases, which improved physical charge separation. CdS-CdO-ZnO catalyst activity was significantly improved by the addition of Pt or Ru cocatalysts. Among the noble metals studied, activity promotion was higher for the sample loaded with Ru. The enhancement of activity associated with Ru loading is linked to a good interaction between Ru oxide particles and CdS, which reduces the possibility of electron-hole recombination, thus resulting in more efficient water splitting. (author)

  13. High density plasma reactive ion etching of Ru thin films using non-corrosive gas mixture

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Su Min; Garay, Adrian Adalberto; Lee, Wan In; Chung, Chee Won, E-mail: cwchung@inha.ac.kr

    2015-07-31

    Inductively coupled plasma reactive ion etching (ICPRIE) of Ru thin films patterned with TiN hard masks was investigated using a CH{sub 3}OH/Ar gas mixture. As the CH{sub 3}OH concentration in CH{sub 3}OH/Ar increased, the etch rates of Ru thin films and TiN hard masks decreased. However, the etch selectivity of Ru films on TiN hard masks increased and the etch slope of Ru film improved at 25% CH{sub 3}OH/Ar. With increasing ICP radiofrequency power and direct current bias voltage and decreasing process pressure, the etch rates of Ru films increased, and the etch profiles were enhanced without redeposition on the sidewall. Optical emission spectroscopy and X-ray photoelectron spectroscopy were employed to analyze the plasma and surface chemistry. Based on these results, Ru thin films were oxidized to RuO{sub 2} and RuO{sub 3} compounds that were removed by sputtering of ions and the etching of Ru thin films followed a physical sputtering with the assistance of chemical reaction. - Highlights: • Etching of Ru films in CH{sub 3}OH/Ar was investigated. • High selectivity and etch profile with high degree of anisotropy were obtained. • XPS analysis was examined to identify the etch chemistry. • During etching Ru was oxidized to RuO{sub 2} and RuO{sub 3} can be easily sputtered off.

  14. Exotic magnetism on the quasi-fcc lattices of the d3 double Perovskites La2NaB'O6 (B'=Ru, Os).

    Science.gov (United States)

    Aczel, A A; Baker, P J; Bugaris, D E; Yeon, J; Zur Loye, H-C; Guidi, T; Adroja, D T

    2014-03-21

    We find evidence for long-range and short-range (ζ=70 Å at 4 K) incommensurate magnetic order on the quasi-face-centered-cubic (fcc) lattices of the monoclinic double perovskites La2NaRuO6 and La2NaOsO6, respectively. Incommensurate magnetic order on the fcc lattice has not been predicted by mean field theory, but may arise via a delicate balance of inequivalent nearest neighbor and next nearest neighbor exchange interactions. In the Ru system with long-range order, inelastic neutron scattering also reveals a spin gap Δ ∼ 2.75 meV. Magnetic anisotropy is generally minimized in the more familiar octahedrally coordinated 3d3 systems, so the large gap observed for La2NaRuO6 may result from the significantly enhanced value of spin-orbit coupling in this 4d(3) material.

  15. Rahasäru veeretas viisimünti / Inna Grünfeldt

    Index Scriptorium Estoniae

    Grünfeldt, Inna, 1961-

    2008-01-01

    Folkloorifestival Viru Säru, mille teemaks seekord "Raha, rikkus ja vaesus", katsus Kadrinas kavasid. Žüriisse kuulusid Viru Säru kunstiline juht Igor Tõnurist, rahvamuusik Margus Veenre ja rahvatantsujuht Angela Arraste. Ka nende arvamused kavade kohta

  16. Atomic states and properties of Ru-electrocatalyst

    Institute of Scientific and Technical Information of China (English)

    PENG Hong-jian; XIE You-qing; WEI De-liang

    2006-01-01

    Using the one-atom theory(OA), the atomic states of Ru-electrocatalyst with hcp structure was determined as [Kr](4dn)3.78(4dc)2.22(5sc)1.77(5sf)0.23. The potential curve, elasticity and the temperature dependence of linear thermal expansion coefficient and bulk modulus of hcp-Ru were calculated quantitatively. The atomic states of this metal with fcc and bcc structure and liquid state were also studied. According to its atomic states, the relationship between the atomic states and catalytic performance was explained qualitatively and these supplied Ru-metal and electrocatalyst with complete data for optimum designation in accordance with metal material systematic sicence.

  17. CATALYTIC AND ELECTROCATALYTIC ACTIVITY OF Pt-Ru/C ELECTRODE FOR HYDROGEN OXIDATION IN ALKALINE

    Directory of Open Access Journals (Sweden)

    D. LABOU

    2008-07-01

    Full Text Available The kinetics of the oxidation of H2 on PtRu/C gas-diffusion electrode was studied by interfacing the electrode with aqueous electrolytes at different pH values. The conducting electrolytes were KOH and HClO4 aqueous solutions with different concentrations. It is shown that the nature of the aqueous electrolyte plays the role of an active catalyst support for the PtRu/C electrode which drastically affects its catalytic properties. During the aforementioned interaction, termed electrochemical metal support interaction (EMSI, the electrochemical potential of the electrons at the catalyst Fermi level is equalised with the electrochemical potential of the solvated electron in the aqueous electrolyte. The electrochemical experiments carried out at various pH values showed that the electrochemical promotion catalysis (EPOC is more intense when the catalyst-electrode is interfaced with electrolytes with high pH values where the OH– ionic conduction prevails. It was concluded that similar to the solid state electrochemical systems EPOC proceeds through the formation of a polar adsorbed promoting layer of , electrochemically supplied by the OH- species, at the three phase boundaries of the gas exposed gas diffusion catalyst-electrode surface.

  18. Crystal growth and characterization of CeFe{sub 1-x}Ru{sub x} PO

    Energy Technology Data Exchange (ETDEWEB)

    Balle, Tanita; Kliemt, Kristin; Krellner, Cornelius [Goethe Universitaet Frankfurt, Kristall- und Materiallabor (Germany)

    2016-07-01

    CeRuPO is a one of the few heavy fermion systems, which order ferromagnetically at low temperatures (T{sub C} = 15 K), because of dominant RKKY-interaction. CeFePO on the other hand shows no long-range magnetic order even at low temperatures because of dominant Kondo effect (T{sub K} = 10 K). By substituting CeFePO with ruthenium we can reach a quantum critical point, at which the RKKY-interaction and the Kondo effect are equally strong. To study the quantum critical point, and to enlighten the question if the order stays ferromagnetically down to lowest temperatures, high quality crystals are needed. Here, the growth and characterization of the single crystals will be discussed. We obtained mm-sized single crystals of the unsubstituted CeRuPO and CeFePO by a modified Bridgeman method using tin as a flux. The quality of the crystals was verified by Powder-X-Ray-Diffraction, energy dispersive X-ray spectroscopy and Laue backscattering.

  19. Ternary Pt-Ru-Ni catalytic layers for methanol electrooxidation prepared by electrodeposition and galvanic replacement

    OpenAIRE

    Athanasios ePapaderakis; Nikolaos ePliatsikas; Chara eProchaska; Kalliopi M. Papazisi; Balomenou, Stella P.; Dimitrios eTsiplakides; Panagiotis ePatsalas; Sotiris eSotiropoulos

    2014-01-01

    Ternary Pt-Ru-Ni deposits on glassy carbon substrates, Pt-Ru(Ni)/GC, have been formed by initial electrodeposition of Ni layers onto glassy carbon electrodes, followed by their partial exchange for Pt and Ru, upon their immersion into equimolar solutions containing complex ions of the precious metals. The overall morphology and composition of the deposits has been studied by SEM microscopy and EDS spectroscopy. Continuous but nodular films have been confirmed, with a Pt ÷ Ru ÷ Ni % bulk atomi...

  20. Molecularly imprinted Ru complex catalysts integrated on oxide surfaces.

    Science.gov (United States)

    Muratsugu, Satoshi; Tada, Mizuki

    2013-02-19

    Selective catalysis is critical for the development of green chemical processes, and natural enzymes that possess specialized three-dimensional reaction pockets with catalytically active sites represent the most sophisticated systems for selective catalysis. A reaction space in an enzyme consists of an active metal center, functional groups for molecular recognition (such as amino acids), and a surrounding protein matrix to prepare the reaction pocket. The artificial design of such an integrated catalytic unit in a non-enzymatic system remains challenging. Molecular imprinting of a supported metal complex provides a promising approach for shape-selective catalysis. In this process, an imprinted cavity with a shape matched to a template molecule is created in a polymer matrix with a catalytically active metal site. In this Account, we review our studies on molecularly imprinted metal complex catalysts, focusing on Ru complexes, on oxide surfaces for shape-selective catalysis. Oxide surface-attached transition metal complex catalysts not only improve thermal stability and catalyst dispersion but also provide unique catalytic performance not observed in homogeneous precursors. We designed molecularly imprinted Ru complexes by using surface-attached Ru complexes with template ligands and inorganic/organic surface matrix overlayers to control the chemical environment around the active metal complex catalysts on oxide surfaces. We prepared the designed, molecularly imprinted Ru complexes on SiO(2) surfaces in a step-by-step manner and characterized them with solid-state (SS) NMR, diffuse-reflectance (DR) UV-vis, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller isotherm (BET), X-ray fluorescence (XRF), and Ru K-edge extended X-ray absorption fine structure (EXAFS). The catalytic performances of these Ru complexes suggest that this process of molecular imprinting facilitates the artificial integration of catalytic functions at surfaces. Further advances such

  1. Specific heat, resistivity, and AC susceptibility of the cubic PrX 2 compounds (X = Pt, Ru, Ir, Rh)

    Science.gov (United States)

    Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; de Jongh, L. J.; Huiskamp, W. J.; Capel, H. W.; Buschow, K. H. J.

    1983-04-01

    Specific-heat, differential-susceptibility and electrical-resistivity measurements on PrX 2 (X = Ir, Pt, Rh, Ru) compounds reveal phase transitions at Tc = 11.2±0.5 K, 7.7±0.5 K, 7.9±0.5 Kand 33.9±0.5 K for X = Ir, Pt, Rh, and Ru, respective ly. From earlier neutron inelastic scattering experiments, the crystalline electric field levels of these compounds have been determined. The specific-heat results are compared with the results of a mean-field calculation, assuming bilinear exchange interactions. The presence of broad secondary maxima in the temperature dependence of the specific heat of PrRh 2, PrRu 2 and especially PrIr 2 can qualitatively be explained by the presence of biquadratic (quadrupolar) interactions. The behaviour of the susceptibility is in agreement with ferromagnetic ordering. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  2. Fuel management simulation for CANFLEX-RU in CANDU 6

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Chang Joon; Suk, Ho Chun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    Fuel management simulations have been performed for CANFLEX-09% RU fuel in the CANDU 6 reactor. In this study, the bi-directional 4-bundle shift fuelling scheme was assumed. The lattice cell and time-average calculation were carried out. The refuelling simulation calculations were performed for 600 full power days. Time-averaged results show good axial power profile with the CANFLEX-RU fuel. During the simulation period, the maximum channel and bundle power were maintained below the licensing limit of CANDU 6 reactor. 7 refs., 4 figs. (Author)

  3. Role of steps in N-2 activation on Ru(0001)

    DEFF Research Database (Denmark)

    Dahl, Søren; Logadottir, Ashildur; Egeberg, Rasmus

    1999-01-01

    Using adsorption experiments and density functional calculations we show that N-2 dissociation on the Ru(0001) surface is totally dominated by steps. The measured adsorption rate at the steps is at least 9 orders of magnitude higher than on the terraces at 500 K, and the corresponding calculated ...... difference in activation energy is 1.5 eV. The low barrier at the step is shown to be due to a combination of electronic and geometrical effects. The consequences for Ru as a catalyst for ammonia synthesis are discussed....

  4. Oxidation resistance of Ru-capped EUV multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bajt, S; Dai, Z; Nelson, E J; Wall, M A; Alameda, J; Nguyen, N; Baker, S; Robinson, J C; Taylor, J S; Clift, M; Aquila, A; Gullikson, E M; Edwards, N G

    2005-02-23

    Differently prepared Ru-capping layers, deposited on Mo/Si EUV multilayers, have been characterized using a suite of metrologies to establish their baseline structural, optical, and surface properties in as-deposited state. Same capping layer structures were tested for their thermal stability and oxidation resistance. Post-mortem characterization identified changes due to accelerated tests. The best performing Ru-capping layer structure was studied in detail with transmission electron microscopy to identify the grain microstructure and texture. This information is essential for modeling and performance optimization of EUVL multilayers.

  5. Symmetry-protected Majorana fermions in topological crystalline superconductors: theory and application to Sr2RuO4.

    Science.gov (United States)

    Ueno, Yuji; Yamakage, Ai; Tanaka, Yukio; Sato, Masatoshi

    2013-08-23

    Crystal point group symmetry is shown to protect Majorana fermions (MFs) in spinfull superconductors (SCs). We elucidate the condition necessary to obtain MFs protected by the point group symmetry. We argue that superconductivity in Sr2RuO4 hosts a topological phase transition to a topological crystalline SC, which accompanies a d-vector rotation under a magnetic field along the c axis. Taking all three bands and spin-orbit interactions into account, symmetry-protected MFs in the topological crystalline SC are identified. Detection of such MFs provides evidence of the d-vector rotation in Sr2RuO4 expected from Knight shift measurements but not yet verified.

  6. RuBee and RFID A confidential summary,May 2009

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The letters"RFID"have become a negative to many of our end-customers,so we have had to distance RuBee from the entire category and discourage any attempt to characterize RuBee as just another RFID technology.We never engage in pilots or trials where RFID is seen as a competing technology to RuBee.Most

  7. New Ru(II) pincer complexes: synthesis, characterization and biological evaluation for photodynamic therapy.

    Science.gov (United States)

    Tabrizi, Leila; Chiniforoshan, Hossein

    2016-11-15

    Three new ruthenium(ii) complexes of NCN pincer and phenylcyanamide derivative ligands of the formula [Ru(L)(Ph2phen)(3,5-(NO2)2pcyd)], 1, [Ru(L)(Me2phen)(3,5-(NO2)2pcyd)], 2, and [Ru(L)(Cl2phen)(3,5-(NO2)2pcyd)], 3 (HL: 5-methoxy-1,3-bis(1-methyl-1H-benzo[d]imidazol-2-yl)benzene, 3,5-(NO2)2pcyd: 3,5-(NO2)2pcyd, Ph2phen: 4,7-diphenyl-1,10-phenanthroline, Me2phen: 4,7-dimethyl-1,10-phenanthroline, Cl2phen: 4,7-dichloro-1,10-phenanthroline) have been synthesized and studied as potential photosensitizers (PSs) in photodynamic therapy (PDT). The complexes exhibited promising (1)O2 production quantum yields comparable with PSs available on the market. The DNA-binding interactions of the complexes with calf thymus DNA have been studied by absorption, emission, and viscosity measurements. All complexes cleave SC-DNA efficiently on photoactivation at 350 nm with the formation of singlet oxygen ((1)O2) and hydroxyl radicals (˙OH) in type-II and photoredox pathways. Complexes 1-3 showed very good uptake in cervical cancer cells (HeLa). The compounds studied were found to exhibit low toxicity against HeLa cells (IC50 > 300 μM) and, remarkably, on non-cancerous MRC-5 cells (IC50 > 100 μM) in the dark. However, 1 showed very promising behavior with an increment of about 90 times, in its cytotoxicity upon light illumination at 420 nm in addition to very good human plasma stability.

  8. Ultrafast Magnetization Dynamics of SrRuO3 Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Langner, Matthew C. [Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2009-05-19

    Itinerant ferromagnet SrRuO3 has drawn interest from physicists due to its unusual transport and magnetic properties as well as from engineers due to its low resistivity and good lattice-matching to other oxide materials. The exact electronic structure remains a mystery, as well as details of the interactions between magnetic and electron transport properties. This thesis describes the use of time-resolved magneto-optical Kerr spectroscopy to study the ferromagnetic resonance of SrRuO3 thin films, where the ferromagnetic resonance is initiated by a sudden change in the easy axis direction in response to a pump pulse. The rotation of the easy axis is induced by laser heating, taking advantage of a temperature-dependent easy axis direction in SrRuO3 thin films. By measuring the change in temperature of the magnetic system in response to the laser pulse, we find that the specific heat is dominated by magnons up to unusually high temperature, ~100 K, and thermal diffusion is limited by a boundary resistance between the film and the substrate that is not consistent with standard phonon reflection and scattering models. We observe a high FMR frequency, 250 GHz, and large Gilbert damping parameter, α ≈1, consistent with strong spin-orbit coupling. We observe a time-dependent change in the easy axis direction on a ps time-scale, and we find that parameters associated with the change in easy axis, as well as the damping parameter, have a non-monotonic temperature dependence similar to that observed in anomalous Hall measurements.

  9. Interface-driven topological Hall effect in SrRuO3-SrIrO3 bilayer.

    Science.gov (United States)

    Matsuno, Jobu; Ogawa, Naoki; Yasuda, Kenji; Kagawa, Fumitaka; Koshibae, Wataru; Nagaosa, Naoto; Tokura, Yoshinori; Kawasaki, Masashi

    2016-07-01

    Electron transport coupled with magnetism has attracted attention over the years. Among them, recently discovered is topological Hall effect (THE), originating from scalar spin chirality, that is, the solid angle subtended by the spins. THE is found to be a promising tool for probing the Dzyaloshinskii-Moriya (DM) interaction and consequent magnetic skyrmions. This interaction arises from broken inversion symmetry and hence can be artificially introduced at interface; this concept is lately verified in metal multilayers. However, there are few attempts to investigate such DM interaction at interface through electron transport. We clarified how the transport properties couple with interface DM interaction by fabricating the epitaxial oxide interface. We observed THE in epitaxial bilayers consisting of ferromagnetic SrRuO3 and paramagnetic SrIrO3 over a wide region of both temperature and magnetic field. The magnitude of THE rapidly decreases with the thickness of SrRuO3, suggesting that the interface DM interaction plays a significant role. Such interaction is expected to realize a 10-nm-sized Néel-type magnetic skyrmion. The present results established that the high-quality oxide interface enables us to tune the effective DM interaction; this can be a step toward future topological electronics.

  10. INTERACT

    DEFF Research Database (Denmark)

    Jochum, Elizabeth; Borggreen, Gunhild; Murphey, TD

    This paper considers the impact of visual art and performance on robotics and human-computer interaction and outlines a research project that combines puppetry and live performance with robotics. Kinesics—communication through movement—is the foundation of many theatre and performance traditions...... interaction between a human operator and an artificial actor or agent. We can apply insights from puppetry to develop culturally-aware robots. Here we describe the development of a robotic marionette theatre wherein robotic controllers assume the role of human puppeteers. The system has been built, tested...

  11. Thermodynamic assessment of the Pdsbnd Rhsbnd Ru system using calphad and first-principles methods

    Science.gov (United States)

    Gossé, S.; Dupin, N.; Guéneau, C.; Crivello, J.-C.; Joubert, J.-M.

    2016-06-01

    Palladium, rhodium and ruthenium are abundant fission products that form in oxide fuels in nuclear reactors. Under operating conditions, these Platinum-Group Metal (PGM) fission products accumulate in high concentration at the rim of the oxide fuel and mainly precipitate into metallic solid solutions. Their thermochemistry is of significant interest to predict the high temperature chemical interactions between the fuel and the cladding or the possible precipitation of PGM phases in high level nuclear waste glasses. To predict the thermodynamic properties of these PGM fission products, a thermodynamic modeling is being developed on the ternary Pdsbnd Rhsbnd Ru system using the Calphad method. Because experimental thermodynamic data are scarce, Special Quasirandom Structures coupled with Density Functional Theory methods were used to calculate mixing enthalpy data in the solid solutions. The resulting thermodynamic description based on only binary interaction parameters is in good agreement with the few data on the ternary system.

  12. Optical probe of Heisenberg-Kitaev magnetism in α -RuCl3

    Science.gov (United States)

    Sandilands, Luke J.; Sohn, C. H.; Park, H. J.; Kim, So Yeun; Kim, K. W.; Sears, Jennifer A.; Kim, Young-June; Noh, Tae Won

    2016-11-01

    We report a temperature-dependent optical spectroscopic study of the Heisenberg-Kitaev magnet α -RuCl3 . Our measurements reveal anomalies in the optical response near the magnetic ordering temperature. At higher temperatures, we observe a redistribution of spectral weight over a broad energy range that is associated with nearest-neighbor spin-spin correlations. This finding is consistent with highly frustrated magnetic interactions and in agreement with theoretical expectations for this class of material. The optical data also reveal significant electron-hole interaction effects, including a bound excitonic state. These results demonstrate a clear coupling between charge and spin degrees of freedom and provide insight into the properties of thermally disordered Heisenberg-Kitaev magnets.

  13. Structure and Physical Properties of SrNiRu5O11 Single Crystals: A New Frustrated R-type Ferrite Based on Ordered Kagome Nets

    Science.gov (United States)

    de Long, Lance; Shlyk, Larysa; Niewa, Rainer

    Single crystals of the R-type ferrite SrNiRu5O11 were grown from a chloride flux. The hexagonal crystal structure contains ruthenium located on Kagome nets, distorted due to formation of Ru-Ru dumbbells via metal-metal bonding. SrNiRu5O11 does not show long-range magnetic order down to 4.5 K. The low-temperature magnetic susceptibilities, χ⊥ and χ/ / c-axis, diverge as T-0.3, and the electric resistivity varies as T1.6 below 40 K, which is typical of non-Fermi liquid materials. This anomalous behavior might originate from the competition between residual magnetic interactions among Ni2+ (S = 1) spins and geometrical frustration on the two-dimensional Kagome lattice of Ru3+ (S = 1/2) spins. The transverse magnetoresistivity ρxy, of a SrNiRu5OSUB11 single crystal at constant temperature T = 5 K for current-magnetic-field configurations, J ⊥H || c-axis and J || H ⊥ c-axis, reveals no anomalous contribution, which is typical for non-magnetic materials. Fits of the heat capacity data below 10 K require a dominant, but unusual electronic term of the form Cel = γT1.2, which is expected for massless Dirac fermion states in topological insulators or spin liquid phases. Research at University of Kentucky supported by U.S. Department of Energy Grant No. DE-FG02-97ER-45653.

  14. STUDY ON POLYMER- Ru- Co BIMETALLIC COMPLEXES CATALYSTS Ⅱ. X-RAY PHOTOELECTRON SPECTROSCOPIC ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    ZONG Huijuan; TANG Qi; CHEN Zonghan; JIANG Yingyan

    1991-01-01

    Polymer-Ru-Co bimetallic complexes have been examined by X-ray photoelectron spectroscopy.The catalyst is highly active only when the mole ratio of Co/Ru is 4:3. The activity of catalysts does not depend on the total Co/Ru ratio, but on the surface stoichiometry of Co and Ru. When the relative intensities of Co2p and Ru3d of XP S peaks are close to each other and both are high, the catalyst exhibits its maximum activity.The mechanism of catalytic hydroformylation has been discussed.

  15. Beta decay of {sup 111}Tc to {sup 111}Ru

    Energy Technology Data Exchange (ETDEWEB)

    Pfeiffer, B.; Kloeckl, I.; Kratz, K.L. [Mainz Univ. (Germany). Inst. fuer Kernchemie; Lhersonneauc, G.; Dendooven, P.; Honkanen, A.; Huhta, M.; Oinonen, M.; Penttilae, H.; Peraejaervi, K.; Wang, J.C.; Aeystoe, J. [Department of Physics, University of Jyvaeskylae, P.O.Box 35, FIN-40351 Jyvaeskylae (Finland); Persson, J.R. [School of Physics and Space Research, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    1998-05-01

    The {beta}-decay of the very neutron-rich {sup 111}Tc nucleus has been observed. A partial decay scheme of {sup 111}Ru is presented, complementing the high-spin levels earlier reported in spontaneous fission work. (orig.) With 1 fig., 2 tabs., 20 refs.

  16. Väike Hüüru ja suur Laagri

    Index Scriptorium Estoniae

    Nirk, Lia

    2016-01-01

    Laagri keskuses asuva Saue vallaraamatukogu ning Hüüru külaseltsi vahel sõlmiti 2014. a. raamleping, mille alusel vallaraamatukogu maksab külaseltsile raamatukoguteenuse osutamise eest ja raamatukoguhoidjaks on MTÜ palgatud kultuuritöötaja

  17. Registration of 'RU9101001'/'Katy' recombinant inbred lines of rice

    Science.gov (United States)

    The cross of RU9101001/'Katy' rice (Oryza sativa L.) was used to develop a mapping population consisting of 238 F9 generation recombinant inbred lines of rice (Oryza sativa L.) (GSOR100361 to GSOR100600). This population has been used to map major genes that provide resistance to the rice blast pat...

  18. Photoacoustic characterization of n-RuSe2 semiconductor pellets

    Science.gov (United States)

    Bernal-Alvarado, J.; Vargas-Luna, M.; Solorza-Feria, O.; Mondragón, R.; Alonso-Vante, N.

    2000-09-01

    Using the open photoacoustic cell technique, a set of physical properties for a semiconductor (n-RuSe2) in powder form was measured. According to the Dramicanin theoretical model, charge carriers transport parameters (bulk and surface) and the effective thermal diffusivity were obtained.

  19. Dissociation of CH4 on Ni(111) and Ru(0001)

    DEFF Research Database (Denmark)

    Egeberg, Rasmus; Ullmann, S.; Alstrup, I.;

    2002-01-01

    the steps were passivated with Au. On Ni(111) sputtering the surface at 500 K with no subsequent annealing increased the initial sticking but at higher coverages this effect vanished. We interpret these results as due to the steps on both surfaces being blocked by carbon species leaving them inaccessible...... to impinging CH4 molecules. We conclude that in these types of experiments steps play a minor role for CH4 dissociation on Ru(0 0 0 1) and Ni(l 1 1). In a temperature programmed oxidation reaction we observe that carbon from the steps of Ru(0 0 0 1) leaves the surface at lower temperatures than carbon from...... the terraces, Finally we have observed a large promotion of the sticking probability of CH4 on Ru(0 0 0 1) by increasing the surface temperature at a fixed gas temperature thus lending support to a mechanism where the dissociation of methane takes place over Ru atoms displaced normal to the surface....

  20. Chemical fingerprinting of algaenans using RuO4 degradation

    NARCIS (Netherlands)

    Blokker, P.; Ende, H. van den; Leeuw, J.W. de; Versteegh, G.J.M.; Sinninghe Damsté, J.S.

    2006-01-01

    The freshwater green microalgae, Oocystus solitaria Wittrock f. maior Wille, Pediastrum braunii Wartmann, Pediastrum kawraiskyi Schmidle, Sorastrum spinulosum Na¨geli and Coelastrum reticulatum (Dangeard) Senn were investigated with respect to the presence of algaenan and the corresponding RuO4 chem

  1. Bonding Characteristics and Magnetic Coupling Interactions in One-dimensional a'-NaV2O5

    Institute of Scientific and Technical Information of China (English)

    FAN Hou-gang; MING Xing; HU Fang; WANG Chun-zhong; HUANG Zu-fei; CHEN Gang

    2009-01-01

    The spin-polarized generalized gradient approximation(GGA)+U approach was employed to study the bonding characteristics and magnetic coupling interactions in room-temperature phase α'-NaV2O5.The calculated results indicate that the Vdxy orbital is split off from other 3d orbitals in the VO5 pyramidal ligand field.The Vdxy orbitads are hybridized strongly with the Opx/py orbitals,forming a V-O-V π bond in the ab plane.The ligand field effect together with the intra-atomic exchange splitting results in the insulating behavior.With the aid of Noodleman's broken symmetry methods,the magnetic exchange constant was derived from mapping the relative energies onto the Heisenberg model.The antiferromagnetic(AFM) exchange energy,J,along the chain was calculated to be-593 K in good agreement with the experimental data.

  2. Photoinduced energy- and electron-transfer processes in dinuclear Ru(II)-Os(II), Ru(II)-Os(III), and Ru(III)-Os(II) trisbipyridine complexes containing a shape-persistent macrocyclic spacer.

    Science.gov (United States)

    Venturi, Margherita; Marchioni, Filippo; Ferrer Ribera, Belén; Balzani, Vincenzo; Opris, Dorina M; Schlüter, A Dieter

    2006-01-16

    The PF6- salt of the dinuclear [(bpy)2Ru(1)Os(bpy)2]4+ complex, where 1 is a phenylacetylene macrocycle which incorporates two 2,2'-bipyridine (bpy) chelating units in opposite sites of its shape-persistent structure, was prepared. In acetonitrile solution, the Ru- and Os-based units display their characteristic absorption spectra and electrochemical properties as in the parent homodinuclear compounds. The luminescence spectrum, however, shows that the emission band of the Ru(II) unit is almost completely quenched with concomitant sensitization of the emission of the Os(II) unit. Electronic energy transfer from the Ru(II) to the Os(II) unit takes place by two distinct processes (k(en) = 2.0x10(8) and 2.2x10(7) s(-1) at 298 K). Oxidation of the Os(II) unit of [(bpy)2Ru(1)Os(bpy)2]4+ by Ce(IV) or nitric acid leads quantitatively to the [(bpy)2Ru(II)(1)Os(III)(bpy)2]5+ complex which exhibits a bpy-to-Os(III) charge-transfer band at 720 nm (epsilon(max) = 250 M(-1) cm(-1)). Light excitation of the Ru(II) unit of [(bpy)2Ru(II)(1)Os(III)(bpy)2]5+ is followed by electron transfer from the Ru(II) to the Os(III) unit (k(el,f) = 1.6x10(8) and 2.7x10(7) s(-1)), resulting in the transient formation of the [(bpy)2Ru(III)(1)Os(II)(bpy)2]5+ complex. The latter species relaxes to the [(bpy)2Ru(II)(1)Os(III)(bpy)2]5+ one by back electron transfer (k(el,b) = 9.1x10(7) and 1.2x10(7) s(-1)). The biexponential decays of the [(bpy)2*Ru(II)(1)Os(II)(bpy)2]4+, [(bpy)2*Ru(II)(1)Os(III)(bpy)2]5+, and [(bpy)2Ru(III)(1)Os(II)(bpy)2]5+ species are related to the presence of two conformers, as expected because of the steric hindrance between hydrogen atoms of the pyridine and phenyl rings. Comparison of the results obtained with those previously reported for other Ru-Os polypyridine complexes shows that the macrocyclic ligand 1 is a relatively poor conducting bridge.

  3. Dark-bright soliton interactions beyond the integrable limit

    Science.gov (United States)

    Katsimiga, G. C.; Stockhofe, J.; Kevrekidis, P. G.; Schmelcher, P.

    2017-01-01

    In this work we present a systematic theoretical analysis regarding dark-bright solitons and their interactions, motivated by recent advances in atomic two-component repulsively interacting Bose-Einstein condensates. In particular, we study analytically via a two-soliton ansatz adopted within a variational formulation the interaction between two dark-bright solitons in a homogeneous environment beyond the integrable regime, by considering general inter- and intra-atomic interaction coefficients. We retrieve the possibility of a fixed point in the case where the bright solitons are out of phase. As the intercomponent interaction is increased, we also identify an exponential instability of the two-soliton state, associated with a subcritical pitchfork bifurcation. The latter gives rise to an asymmetric partition of the bright soliton mass and dynamically leads to spontaneous splitting of the bound pair. In the case of the in-phase bright solitons, we explain via parsing the analytical approximations and monitoring the direct dynamics why no such pair is identified, despite its prediction by the variational analysis.

  4. Spectroscopic, Electrochemical and Computational Characterisation of Ru Species Involved in Catalytic Water Oxidation: Evidence for a [RuV(O)(Py2Metacn)] Intermediate

    OpenAIRE

    Casadevall, Carla; Codolà Duch, Zoel; Costas Salgueiro, Miquel; Lloret Fillol, Julio

    2016-01-01

    A new family of ruthenium complexes based on the N-pentadentate ligand Py2Metacn (N-methyl-N′,N′′-bis(2-picolyl)-1,4,7-triazacyclononane) has been synthesised and its catalytic activity has been studied in the water-oxidation (WO) reaction. We have used chemical oxidants (ceric ammonium nitrate and NaIO4) to generate the WO intermediates [RuII(OH2)(Py2Metacn)]2+, [RuIII(OH2)(Py2Metacn)]3+, [RuIII(OH)(Py2Metacn)]2+ and [RuIV(O)(Py2Metacn)]2+, which have been characterised spectroscopically. Th...

  5. Mechanism of -O-O- bond activation and catalysis by RuIII-pac complexes (pac = polyaminocarboxylate)

    Indian Academy of Sciences (India)

    Debabrata Chatterjee

    2012-11-01

    This paper presents the mechanistic aspects of the -O-O- bond activation by the Ru-pac (pac = polyaminocarboxylate) complex leading to the formation of various catalytic active species, viz. [RuIII(pac)(OOH)]2−, [RuIV(pac)(OH)]− and [RuV(pac)(O)]−, and their reactivity towards oxidation of a few organic compounds.

  6. Mechanism of RuO2 crystallization in borosilicate glass: an original in situ ESEM approach.

    Science.gov (United States)

    Boucetta, Hassiba; Podor, Renaud; Stievano, Lorenzo; Ravaux, Johann; Carrier, Xavier; Casale, Sandra; Gossé, Stéphane; Monteiro, Amélie; Schuller, Sophie

    2012-03-19

    Ruthenium, a fission product arising from the reprocessing of spent uranium oxide (UOX) fuel, crystallizes in the form of acicular RuO(2) particles in high-level waste containment glass matrices. These particles are responsible for significant modifications in the physicochemical behavior of the glass in the liquid state, and their formation mechanisms are a subject of investigation. The chemical reactions responsible for the crystallization of RuO(2) particles with acicular or polyhedral shape in simplified radioactive waste containment glass are described. In situ high-temperature environmental scanning electron microscopy (ESEM) is used to follow changes in morphology and composition of the ruthenium compounds formed by reactions at high temperature between a simplified RuO(2)-NaNO(3) precursor and a sodium borosilicate glass (SiO(2)-B(2)O(3)-Na(2)O). The key parameter in the formation of acicular or polyhedral RuO(2) crystals is the chemistry of the ruthenium compound under oxidized conditions (Ru(IV), Ru(V)). The precipitation of needle-shaped RuO(2) crystals in the melt might be associated with the formation of an intermediate Ru compound (Na(3)Ru(V)O(4)) before dissolution in the melt, allowing Ru concentration gradients. The formation of polyhedral crystals is the result of the direct incorporation of RuO(2) crystals in the melt followed by an Ostwald ripening mechanism.

  7. Enhancement of ferromagnetism by oxygen isotope substitution in strontium ruthenate SrRuO3

    Science.gov (United States)

    Kawanaka, Hirofumi; Aiura, Yoshihiro; Hasebe, Takayuki; Yokoyama, Makoto; Masui, Takahiko; Nishihara, Yoshikazu; Yanagisawa, Takashi

    2016-10-01

    The oxygen isotope effect of the ferromagnetic transition in itinerant ferromagnet strontium ruthenate SrRuO3 with a Curie temperature Tc of 160 K is studied. We observed for the first time a shift of ∆Tc ~ 1 K by oxygen isotope substitution of 16O → 18O in SrRuO3 by precise measurements of DC and AC magnetizations. The results surprisingly lead to the noteworthy inverse isotope effect with negative coefficient α = -∂ lnTc/∂ lnM. The Raman spectra indicate that the main vibration frequency of 16O at 363 cm-1 shifts to 341 cm-1 following oxygen isotope substitution 18O. This shift is remarkably consistent with the Debye frequency being proportional to ∝ 1√M where M is the mass of an oxygen atom. The positive isotope shift of ∆Tc can be understood by taking account of the electron-phonon interaction.

  8. Atomic layer deposition of Ru from CpRu(CO)(2)Et using O-2 gas and O-2 plasma

    NARCIS (Netherlands)

    Leick, N.; Verkuijlen, R. O. F.; Lamagna, L.; Langereis, E.; Rushworth, S.; Roozeboom, F.; M. C. M. van de Sanden,; Kessels, W. M. M.

    2011-01-01

    The metalorganic precursor cyclopentadienylethyl(dicarbonyl)ruthenium (CpRu(CO)(2)Et) was used to develop an atomic layer deposition (ALD) process for ruthenium. O-2 gas and O-2 plasma were employed as reactants. For both processes, thermal and plasma-assisted ALD, a relatively high growth-per-cycle

  9. Methanol electro-oxidation on Pt-Ru-P/C and Pt-Ru-P/MWCNT in acidic medium

    CSIR Research Space (South Africa)

    Modibedi, M

    2009-06-01

    Full Text Available Pt-Ru-P was prepared by the chemical reduction method using sodium hypophoshite as a reducing agent on Vulcan XC 72 and multi-walled carbon nano-tubes (MWCNTs). Sodium citrate was added as the stabilizer during electro-catalyst preparation...

  10. Structural investigations in BaFe(2-x)Ru(x)As2 as a function of Ru and temperature.

    Science.gov (United States)

    Sharma, Shilpam; Bharathi, A; Vinod, K; Sundar, C S; Srihari, V; Sen, Smritijit; Ghosh, Haranath; Sinha, Anil K; Deb, S K

    2015-02-01

    We present the results of synchrotron X-ray diffraction (XRD) measurements on powdered single-crystal samples of BaFe(2-x)Ru(x)As2, as a function of Ru content, and as a function of temperature, across the spin-density wave transition in BaFe(1.9)Ru(0.1)As2. The Rietveld refinements reveal that with Ru substitution, while the a-axis increases, the c-axis decreases. In addition, the variation of positional coordinates of As (z(As)), the Fe-As bond length and the As-Fe-As bond angles have also been determined. In the sample with x = 0.1, temperature-dependent XRD measurements indicate that the orthorhombicity shows the characteristic increase with a decrease in temperature, below the magnetic transition. It is seen that the c-axis, the As-Fe-As bond angles, Fe-As bond length and positional coordinates of the As show definite anomalies close to the structural transition. The observed anomalies in structural parameters are analysed in conjunction with restricted geometric optimization of the structure using ab initio electronic structure calculations.

  11. Automated direct assay system for RU38486, an antiprogesterone-antiglucocorticoid agent, and its metabolites using high performance liquid chromatography.

    Directory of Open Access Journals (Sweden)

    Nagoshi,Kazusuke

    1991-04-01

    Full Text Available An automated direct assay system using high performance liquid chromatography was developed for the measurement of RU38486 and its three metabolites (RU42698, RU42848, RU42633 in human serum. Serum concentrations of these compounds were measured up to 144 h following single oral administration of 200 (200 mg group, n = 3 or 400 mg (400 mg group, n = 3 of RU38486 to healthy female volunteers. The serum half-lives (200 mg group-400 mg group of RU38486, RU42698, RU42848 and RU42633 were 31.8-33.1 h, 41.2-39.3 h, 33.9-36.6 h and 29.2-36.6 h, respectively. Our system could quantify them easily and simultaneously, and was considered to be valuable in studies on the relationship between the pharmacokinetics and the clinical effects of RU38486.

  12. Interactions

    DEFF Research Database (Denmark)

    The main theme of this anthology is the unique interaction between mathematics, physics and philosophy during the beginning of the 20th century. Seminal theories of modern physics and new fundamental mathematical structures were discovered or formed in this period. Significant physicists...... such as Lorentz and Einstein as well as mathematicians such as Poincare, Minkowski, Hilbert and Weyl contributed to this development. They created the new physical theories and the mathematical disciplines that play such paramount roles in their mathematical formulations. These physicists and mathematicians were...

  13. Impact of IrRu oxygen evolution reaction catalysts on Pt nanostructured thin films under start-up/shutdown cycling

    Science.gov (United States)

    Cullen, David A.; More, Karren L.; Atanasoska, Ljiljana L.; Atanasoski, Radoslav T.

    2014-12-01

    Electron microscopy and X-ray photoelectron spectroscopy (XPS) were utilized to study the role of oxygen evolution reaction (OER) catalysts in mitigating degradation arising from start-up/shutdown events. Pt nanostructured thin films (NSTF) were coated with a Ru0.1Ir0.9 OER catalyst at loadings ranging from 1 to 10 μg cm-2 and submitted to 5000 potential cycles within a membrane electrode assembly. Analysis of the as-deposited catalyst showed that the Ir and Ru coating is primarily metallic, and further evidence is provided to support the previously reported interaction between Ru and the perylene-red support. Aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy were used to observe the impact of the OER catalysts on Pt dissolution and migration into the membrane. Elemental mapping showed a high percentage of the Ir catalyst was maintained on the NSTF whisker surfaces following testing. The presence of the OER catalysts greatly reduced the smoothing of the Pt NSTF whiskers, which has been correlated with Pt dissolution and losses in electrochemically active surface area. The dissolution of both Ir and Pt led to the formation of IrPt nanoparticle clusters in the membrane close to the cathode, as well as the formation of a Pt band deeper in the membrane.

  14. Magnetic, electronic, high-spin polarization and half-metallic properties of Ru2VGe and Ru2VSb Heusler alloys: An FP-LAPW study

    Science.gov (United States)

    Gupta, Dinesh C.; Bhat, Idris H.

    2015-01-01

    Electronic and magnetic properties of Ru2VGe and Ru2VSb have been calculated using full potential linearized augmented plane wane method. The optimized equilibrium lattice constants in stable Fm-3m configuration were found to be 6.032 Å for Ru2VGe and 6.272 Å for Ru2VSb. Spin-resolved calculations show that V mainly contributes to the magnetic properties in these materials. The materials follow the Slater-Pauling rule and hence have integral magnetic moments which is due to 100% spin polarization at Fermi energy. The calculated total magnetic moments per unit cell were found to be 1.0 μB for Ru2VGe and 2.0 μB for Ru2VSb. Both the materials having ferromagnetic ground state, exhibit half-metallicity with an energy gap in the spin-down channel of 0.095 eV for Ru2VGe and 0.186 eV for Ru2VSb.

  15. Crystal structure of the Nd(Ru{sub 0.6}Ge{sub 0.4}){sub 2} and ErRuGe compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rizzoli, C.; Sologub, O.; Salamakha, P

    2003-02-17

    Using X-ray powder and single crystal diffraction, the crystal structures of the Nd(Ru{sub 0.6}Ge{sub 0.4}){sub 2} and ErRuGe compounds were investigated. The compounds belong to the KHg{sub 2} and TiNiSi type structure, respectively.

  16. Indole cyanation via C-H bond activation under catalysis of Ru(Ⅲ)-exchanged NaY zeolite (RuY) as a recyclable catalyst

    Institute of Scientific and Technical Information of China (English)

    Alireza Khorshidi

    2012-01-01

    Selective 3-cyanation of indoles was achieved under heterogeneous catalysis of Ru(Ⅲ)-exchanged NaY zeolite (RuY) as a recyclable catalyst,in combination with K4[Fe(CN)6] as a nontoxic,slow cyanide releasing agent.Under the aforementioned conditions,good yields of the desired products were obtained.

  17. Self-assembly of Ru4 and Ru8 assemblies by coordination using organometallic Ru(II2 precursors: Synthesis, characterization and properties

    Directory of Open Access Journals (Sweden)

    Sankarasekaran Shanmugaraju

    2012-02-01

    Full Text Available Coordination-driven self-assembly of binuclear half-sandwich p-cymene ruthenium(II complexes [Ru2(μ-η4-C2O4(MeOH2(η6-p-cymene2](O3SCF32 (1a or [Ru2(μ-η4-N,N'-diphenyloxamidato(MeOH2(η6-p-cymene2](O3SCF32 (1b separately with an imidazole-based tetratopic donor L in methanol affords two tetranuclear metallamacrocycles 2a and 2b, respectively. Conversely, the similar combination of L with 2,5-dihydroxy-1,4-benzoquinonato (dhbq bridged binuclear complex [Ru2(μ-η4-C6H2O4(MeOH2(η6-p-cymene2](O3SCF32 (1c in 1:2 molar ratio resulted in an octanuclear macrocyclic cage 2c. All the self-assembled macrocycles 2a–2c were isolated as their triflate salts in high yields and were characterized fully by multinuclear (1H, 13C and 19F NMR, infrared (IR and electrospray ionization mass spectrometry (ESIMS. In addition, the molecular structure of macrocycle 2a was established unequivocally by single-crystal X-ray diffraction analysis and adopts a tetranuclear rectangular geometry with the dimensions of 5.53 Å × 12.39 Å. Furthermore, the photo- and electrochemical properties of these newly synthesized assemblies have been studied by using UV–vis absorption and cyclic voltammetry analysis.

  18. First Measurement of the $^{96}$Ru(p,$\\gamma$)$^{97}$Rh Cross Section for the p-Process with a Storage Ring

    CERN Document Server

    Mei, Bo; Bishop, Shawn; Blaum, Klaus; Boretzky, Konstanze; Bosch, Fritz; Brandau, Carsten; Bräuning, Harald; Davinson, Thomas; Dillmann, Iris; Dimopoulou, Christina; Ershova, Olga; Fülöp, Zsolt; Geissel, Hans; Glorius, Jan; Gyürky, György; Heil, Michael; Käppeler, Franz; Kelic-Heil, Aleksandra; Kozhuharov, Christophor; Langer, Christoph; Bleis, Tudi Le; Litvinov, Yuri; Lotay, Gavin; Marganiec, Justyna; Münzenberg, Gottfried; Nolden, Fritz; Petridis, Nikolaos; Plag, Ralf; Popp, Ulrich; Rastrepina, Ganna; Reifarth, René; Riese, Björn; Rigollet, Catherine; Scheidenberger, Christoph; Simon, Haik; Sonnabend, Kerstin; Steck, Markus; Stöhlke, Thomas; Szücs, Tamás; Sümmerer, Klaus; Weber, Günter; Weick, Helmut; Winters, Danyal; Winters, Natalya; Woods, Philip; Zhong, Qiping

    2015-01-01

    This work presents a direct measurement of the $^{96}$Ru($p, \\gamma$)$^{97}$Rh cross section via a novel technique using a storage ring, which opens opportunities for reaction measurements on unstable nuclei. A proof-of-principle experiment was performed at the storage ring ESR at GSI in Darmstadt, where circulating $^{96}$Ru ions interacted repeatedly with a hydrogen target. The $^{96}$Ru($p, \\gamma$)$^{97}$Rh cross section between 9 and 11 MeV has been determined using two independent normalization methods. As key ingredients in Hauser-Feshbach calculations, the $\\gamma$-ray strength function as well as the level density model can be pinned down with the measured ($p, \\gamma$) cross section. Furthermore, the proton optical potential can be optimized after the uncertainties from the $\\gamma$-ray strength function and the level density have been removed. As a result, a constrained $^{96}$Ru($p, \\gamma$)$^{97}$Rh reaction rate over a wide temperature range is recommended for $p$-process network calculations.

  19. Low-temperature properties of Ce(Ru{sub 1-x} M{sub x}){sub 2} Ge{sub 2}, M = Fe,Au

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, M.B.; El-Massalami, M.; Aliaga-Guerra, D.; Giordanengo, B.; Bud ko, S.L.; Guimaraes, A.P.; Baggio-Saitovitch, E.M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Gavilano, J.L. [Eidgenoessische Technische Hochschule, Zurich (Switzerland). Lab. fuer Festkoerperphysik

    1994-10-01

    Measurements were performed of electrical resistivity, AC susceptibility, magnetization, Moessbauer effect and NMR on the series of intermetallic compounds Ce(Ru{sub 1-x} M{sub x}) Ge{sub 2}, M = Fe, Au for 0 {<=} x {<=} 0.1. The parent compound Ce Ru{sub 2} Ge{sub 2} orders ferromagnetically below 7.5 K, with f-electron showing only a small mass-enhancement at low temperatures. However, its crystal structure and Fermi surface are closely related to the heavy-electron superconductor Ce Ru{sub 2} Si{sub 2}. Analysis of X-ray diffraction patterns confirmed the structure to be of the Th Cr{sub 2} Si{sub 2}-type, with no foreign phases detected. The results of our Moessbauer studies indicate that Fe goes into the Ru sites with no magnetic moment. NMR signals were observed in the Fe-doped samples with quadrupolar interaction that can be related to {sup 73} Ge nucleus (I=9/2). (author). 8 refs, 3 figs.

  20. Low-temperature properties of Ce(Ru{sub 1-x}M{sub x}){sub 2}Ge{sub 2}, M=Fe, Au

    Energy Technology Data Exchange (ETDEWEB)

    Fontes, M.B. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Elmassalami, M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Aliaga-Guerra, D. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Giordanengo, B. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Budko, S.L. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Guimaraes, A.P. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Gavilano, J.L. [Laboratorium fuer Festkoerperphysik, ETH-Hoenggerberg, 8093 Zuerich (Switzerland); Baggio-Saitovitch, E.M. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    1995-03-01

    We have performed measurements of electrical resistivity, AC susceptibility, magnetization, Moessbauer effect and NMR on the series of intermetallic compounds Ce(Ru{sub 1-x}M{sub x}){sub 2}Ge{sub 2}, M=Fe, Au for 0{<=}x{<=}0.1. The parent compound CeRu{sub 2}Ge{sub 2} orders ferromagnetically below 7.5 K, with f-electrons showing only a small mass-enhancement at low temperatures. However, its crystal structure and Fermi surface are closely related to the heavy-electron superconductor CeRu{sub 2}Si{sub 2}. Analysis of X-ray diffraction patterns confirmed the structure to be of the ThCr{sub 2}Si{sub 2}-type, with no foreign phases detected. The results of our Moessbauer studies indicate that Fe goes into the Ru sites with no magnetic moment. NMR signals were observed in the Fe-doped samples with quadrupolar interaction that can be related to {sup 73}Ge nucleus (I=9/2). ((orig.)).

  1. Electrical transport and magnetic behaviors of La0.67Sr0.33Mn1-xBxO3 (B = Cr, Ru)

    Science.gov (United States)

    Acharya, Deepshikha; Bhargav, Abhinav; Tank, Tejas M.; Sanyal, Sankar P.

    2016-05-01

    Polycrystalline samples of La0.67Sr0.33Mn1-xCrxO3 (with x=0, 0.05 and 0.1) and La0.67Sr0.33Mn1-xRuxO3 (with x = 0.05 and 0.1) were synthesized using the conventional solid state reaction route and found single phase in nature. Electrical resistivity measurements as a function of temperature in range 5 K-400 K and as a function of magnetic field up to 5 Tesla were performed using d.c. four-probe method. Magnetization data were acquired as a function of temperature in a range 10 K-400 K with an applied magnetic field of 500 Oe. When Mn is partially substituted by Cr and Ru the system displays dramatic changes in the electrical transport behavior and shows double-peaked feature in resistivity curve. Both Cr and Ru substitutions effectively reduce insulator-metal transition (TP) and paramagnetic-ferromagnetic transition (TC) temperatures implying that there might exist FM interaction between Mn+3 and Cr+3 as well Mn+3 and Ru+4. The largest low-temperature magnetoresistance (MR%) is attributed to grain boundary effects and difference in size disorder for Cr and Ru substituted compounds.

  2. Electrochemiluminescent biosensor of ATP using tetrahedron structured DNA and a functional oligonucleotide for Ru(phen)3(2+) intercalation and target identification.

    Science.gov (United States)

    Bu, Nan-Nan; Gao, Ai; He, Xi-Wen; Yin, Xue-Bo

    2013-05-15

    Restricted target accessibility and surface-induced perturbation of the aptamer structure are the main limitations in single-stranded DNA aptamer-based electrochemical sensors. Chemical labeling of the aptamer with a probe at the end of aptamer is inefficient and time-consuming. In this work, tetrahedron-structured DNA (ts-DNA) and a functionalized oligonucleotide (FO) were used to develop an electrochemiluminescence (ECL) aptasensor with adenosine triphosphate (ATP) as a model target. The ts-DNA was formed with three thiolated oligonucleotides and one oligonucleotide containing anti-ATP aptamer. The FO contained a complementary strand to the anti-ATP aptamer and an intermolecular duplex for Ru(phen)3(2+) intercalation. After the ts-DNA was immobilized on the electrode surface through gold-thiol interactions, hybridization between the anti-ATP aptamer and its complementary strand introduced the intercalated Ru(phen)3(2+) to the electrode. ECL emission from Ru(phen)3(2+) was observed with tripropylamine as a co-reactant. Once ATP reacted with its aptamer, the aptamer-complimentary strand duplex dissociated and the intermolecular duplex containing Ru(phen)3(2+) was released. The difference in emission before and after reaction with ATP was used to quantify ATP with a detection limit of 0.2nM. The ts-DNA increased the sensitivity compared to conventional methods, and the intercalation strategy avoided a complex chemical labeling procedure.

  3. Was photosynthetic RuBisCO recruited by acquisitive evolution from RuBisCO-like proteins involved in sulfur metabolism?

    Science.gov (United States)

    Ashida, Hiroki; Danchin, Antoine; Yokota, Akiho

    2005-01-01

    Genome analyses have revealed that the genomes of non-photosynthetic bacteria including Bacillus subtilis code for proteins similar to the large subunit of RuBisCO (called RuBisCO-like protein (RLP)). This raises a fundamental question as to their functional relationship to photosynthetic RuBisCO. Recently, we identified the RLP of B. subtilis as the 2,3-diketo-5-methylthiopentyl-1-phosphate enolase in the methionine salvage pathway. In this mini-review, we suggest functional and evolutionary links between B. subtilis RLP and photosynthetic RuBisCO. Furthermore, we propose that photosynthetic RuBisCOs evolved from RLPs similar to that found in B. subtilis.

  4. A rechargeable hydrogen battery based on Ru catalysis.

    Science.gov (United States)

    Hsu, Shih-Fan; Rommel, Susanne; Eversfield, Philipp; Muller, Keven; Klemm, Elias; Thiel, Werner R; Plietker, Bernd

    2014-07-01

    Apart from energy generation, the storage and liberation of energy are among the major problems in establishing a sustainable energy supply chain. Herein we report the development of a rechargeable H2 battery which is based on the principle of the Ru-catalyzed hydrogenation of CO2 to formic acid (charging process) and the Ru-catalyzed decomposition of formic acid to CO2 and H2 (discharging process). Both processes are driven by the same catalyst at elevated temperature either under pressure (charging process) or pressure-free conditions (discharging process). Up to five charging-discharging cycles were performed without decrease of storage capacity. The resulting CO2/H2 mixture is free of CO and can be employed directly in fuel-cell technology.

  5. Metamagnetic domains in [Co/Pt]/Ru multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, N.S. [IFW Dresden (Germany); Donetsk Inst. for Physics and Technology (Russian Federation); Bran, C.; Wolff, U.; Schultz, L.; Bogdanov, A.N.; Neu, V.; Roessler, U.K. [IFW Dresden (Germany); Hellwig, O. [Hitachi GST, San Jose (United States)

    2009-07-01

    In antiferromagnetically coupled superlattices with perpendicular anisotropy, a magnetic field induces a cascade of reorientation transitions accompanied by metamagnetic multidomain states. For a micromagnetic model, we derive equilibrium sizes of stripe and bubble metamagnetic domains as functions of the antiferromagnetic exchange, magnetic field, and geometrical parameters of the multilayers. Magnetic phase diagrams display three different types of metamagnetic domains which separate the ferrimagnetic state from the antiferromagnetic and the saturated ferromagnetic state, and from ferrostripe phases. Experimental investigations have been carried out for an antiferromagnetically coupled [(Co/Pt){sub 8}Co/Ru]{sub 18} superlattice. Magnetic force microscopy (MFM) imaging in a magnetic fields reveals peculiarities of the nucleation and evolution of metamagnetic domains. Theoretical analysis of MFM data and the magnetization curves gives a consistent description of the magnetization processes in [Co/Pt]/Ru multilayers. Demagnetization processes starting from the multidomain metamagnetic states lead to specific remanents states, namely metamagnetic band and bubble topological defects.

  6. Novel Ru - K/Carbon Nanotubes Catalyst for Ammonia Synthesis

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel ammonia synthesis catalyst, potassium-promoted ruthenium supported on carbon nanotubes, was developed. It was found that the Ru-K/carbon nanotubes catalyst had higher activity for ammonia synthesis ( 20.85 ml NH 3 /h/g-cat ) than the Ru-K/fullerenes ( 13.3 ml NH 3 /h/g-cat ) at atmospheric ressure and 623 K. The catalyst had activity even at 473 K, and had the highest activity ( 23.46 ml NH 3 /h/g-cat ) at 643 K. It was suggested that the multi-walled structure favored the electron transfer, the hydrogen-storage and the hydrogen-spill which were favorable to ammonia synthesis.

  7. Nature of the Excited States of the Even-Even 98-108 Ru Isotopes

    Directory of Open Access Journals (Sweden)

    Eid S. A.

    2008-10-01

    Full Text Available The positive and negative parity states of the even-even 98-108 Ru isotopes are studied within the frame work of the interacting boson approximation model (IBA-1. The calculated levels energy, potential energy surfaces, $V(eta,gamma$, and the electromagnetic transition probabilities, B(E1 and B(E2, show that ruthenium isotopes are transitional nuclei. Staggering effectle, $Delta I = 1$, has been observed between the positive and negative parity states in some of ruthenium isotopes. The electric monopole strength, X(E0/E2, has been calculated. All calculated values are compared with the available experimental and theoretical data wher reasonable agreement has obtained.

  8. Weyl fermions and spin dynamics of metallic ferromagnet SrRuO3

    Science.gov (United States)

    Itoh, Shinichi; Endoh, Yasuo; Yokoo, Tetsuya; Ibuka, Soshi; Park, Je-Geun; Kaneko, Yoshio; Takahashi, Kei S.; Tokura, Yoshinori; Nagaosa, Naoto

    2016-06-01

    Weyl fermions that emerge at band crossings in momentum space caused by the spin-orbit interaction act as magnetic monopoles of the Berry curvature and contribute to a variety of novel transport phenomena such as anomalous Hall effect and magnetoresistance. However, their roles in other physical properties remain mostly unexplored. Here, we provide evidence by neutron Brillouin scattering that the spin dynamics of the metallic ferromagnet SrRuO3 in the very low energy range of milli-electron volts is closely relevant to Weyl fermions near Fermi energy. Although the observed spin wave dispersion is well described by the quadratic momentum dependence, the temperature dependence of the spin wave gap shows a nonmonotonous behaviour, which can be related to that of the anomalous Hall conductivity. This shows that the spin dynamics directly reflects the crucial role of Weyl fermions in the metallic ferromagnet.

  9. Olefin hydroformylation catalysis with RuCl2(DMSO4.

    Directory of Open Access Journals (Sweden)

    Marisela Reyes*

    2008-05-01

    Full Text Available The RuCl2(DMSO4 complex was used as catalytic precursor in olefin hydroformylation reactions, giving good percent yield and better selectivity for linear aldehydes. The reactions were tested in homogeneous medium and biphasic organic solvent/ water systems. The substrates tried were 1-hexene, cyclohexene, 2-methyl-2-pentene, 2,3-dimethyl-2-butene; binary mixtures and synthetic naphtha and real naphtha. The activity is better for linear olefins compared with substituted olefins.

  10. Comparing Ru and Fe-catalyzed olefin metathesis.

    Science.gov (United States)

    Poater, Albert; Chaitanya Vummaleti, Sai Vikrama; Pump, Eva; Cavallo, Luigi

    2014-08-01

    Density functional theory calculations have been used to explore the potential of Fe-based complexes with an N-heterocyclic carbene ligand, as olefin metathesis catalysts. Apart from a less endothermic reaction energy profile, a small reduction in the predicted upper energy barriers (≈ 2 kcal mol(-1)) is calculated in the Fe catalyzed profile with respect to the Ru catalysed profile. Overall, this study indicates that Fe-based catalysts have the potential to be very effective olefin metathesis catalysts.

  11. Core-level photoemission from alkali metals on Ru(001)

    Energy Technology Data Exchange (ETDEWEB)

    Shek, M. (Department of Physics, Hunter College of The City University of New York, New York, New York 10021 (USA)); Hrbek, J. (Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000 (USA)); Sham, T.K. (Department of Chemistry, University of Western Ontario, London, Ontario, Canada NA65B7 (Canada)); Xu, G. (Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000 (USA))

    1990-02-15

    We report soft-x-ray photoemission results on the core-level binding energies of Li, Na, K, and Cs adsorbed on Ru(001). For all four alkali metals, the saturated alkali-metal--Ru interface core level and the second- (surface-) layer core-level binding energies differ by as much as 0.85--1.25 eV. Surface versus bulklike core-level shifts are reported for Li, K, and Cs, which are 0.55 eV for Li and {similar to}0.25 eV for the other two. For increasing coverages of Li, Na, and K in direct contact with Ru, there are significant decreases in the core-level binding energies, the total shift ranging from {similar to}{minus}1.25 eV for Li to {similar to}{minus}0.80 eV for K; the shift for Cs is small and the reasons for the deviation are discussed. A comparison between our observations and the prediction from the thermodynamic model of Johannson and Martensson is also given.

  12. Aluminum thin film growth on a Ru(0001) surface

    Science.gov (United States)

    Ceballos, G.; Theis, M.; Pelzer, Th.; Schick, M.; Rangelov, G.; Wandelt, K.

    1995-07-01

    The growth of thin Al films on a Ru(0001) substrate has been investigated by means of AES, LEED, TDS, and PAX measurements. A plot of the Ru and Al AES intensities versus evaporation time for a deposition temperature of 300 K reveals a distinct break at θAl = 1, while for higher coverages the Ru intensity decays exponentially indicating a three-dimensional growth of Al clusters. From this behavior we deduce a Stranski-Krastanov growth mechanism. This behavior persists up to 650 K. For higher deposition temperatures a diffusion of Al into the substrate and a partial desorption of the Al film is found. At low Al coverage the LEED pattern reveals an initial film growth with Al(111) structure and an expansion of the interatomic spacing of 2% compared to the Al(111) bulk plane. This superstructure persisted up to ˜ 2.5 ML. In the submonolayer regime CO and Xe TD-spectra as well as Xe 4d PAX-spectra suggest together with LEED an island growth.

  13. Low-spin excitations in {sup 98}Ru

    Energy Technology Data Exchange (ETDEWEB)

    Radeck, Desiree; Albers, Michael; Bernards, Christian; Fransen, Christoph; Jolie, Jan; Muecher, Dennis [Institut fuer Kernphysik, Universitaet Koeln (Germany)

    2009-07-01

    In the context of collectivity in the A=100 mass region N=52 isotones were investigated in detail and phonon excitations - especially the mixed-symmetry (MS) states - were identified. In order to investigate how states with this MS character evolve with increasing valence neutron number N=54 isotones were studied. While in {sup 96}Mo the one-phonon MS state 2{sup +}{sub 1,ms} was identified, {sup 98}Ru shows a breakdown of vibrational structure above the two-phonon triplet and no candidate for the 2{sup +}{sub 1,ms} state was assigned. The recently investigated N=54 isotone {sup 100}Pd was explained well with an U{sub {pi}}{sub {nu}}(5) fit within the IBM-2. Furthermore, a candidate for the one-phonon MS2{sup +}{sub 1,ms} state was determined. To do further investigations on the N=54 isotone {sup 98}Ru - in particular regarding the breakdown of vibrational symmetry and the one-phonon MS excitation - an experiment was performed at the Cologne Tandem Accelerator using the HORUS spectrometer. The nuclei were populated by the reaction {sup 97}Mo({sup 3}He,2n){sup 98}Ru. By analysing the coincidence and {gamma}{gamma} angular correlation data the level scheme was extended and clarified by determining spins, multipole mixing ratios and branching ratios. The low-energy excitations of positive parity are discussed and compared to theoretical expectations. The results are compared with those for other N=54 isotones.

  14. Optical spectroscopy of RU Cam, a pulsating carbon star

    CERN Document Server

    Kipper, Tonu

    2007-01-01

    We analysed the high resolution spectra of a RU Cam, classified as W Vir type star. The atmospheric parameters of RU Cam were estimated Teff=5250K and log g=1.0. The hydrogen deficiency of RU Cam was not confirmed. The iron abundance, [Fe/H]=-0.37, is close to the solar one. Abundances of most other elements are also close to normal. We found considerable excesses of carbon and nitrogen: [C/Fe]=+0.98, [N/Fe]=+0.60. The carbon to oxygen ratio is C/O$\\ge$1. The carbon isotopic abundance ratio is equal to C^12/C^13=4.5. For sodium a moderate overabundance Na/Fe=+0.55 was obtained. For two moments of observations we found close heliocentric velocity values, Vr=-21.7+/-0.8 and -23.1+/-1.0 km/s. Both spectra contain a peculiar feature - an emission component of NaI doublet which location agrees with the radial velocity from the bulk of metallic lines. For our two observing moments we found no dependence of radial velocities on the formation depth or on excitation energy for metallic lines.

  15. Reactivity of periodically rippled graphene grown on Ru(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Borca, B; Calleja, F; Hinarejos, J J; Vazquez de Parga, A L; Miranda, R [Departamento de Fisica de la Materia Condensada, Universidad Autonoma de Madrid, Cantoblanco, E-28049 Madrid (Spain)

    2009-04-01

    We report here the reactivity of epitaxial graphene islands and complete monolayers on Ru(0001) towards molecular oxygen and air. The graphene is prepared by thermal decomposition of ethylene molecules pre-adsorbed on an Ru(0001) surface in an ultra-high vacuum chamber. The graphene layer presents a periodically rippled structure that is dictated by the misfit between graphene and Ru(0001) lattice parameters. The periodic ripples produce spatial charge redistribution in the graphene and modifies its electronic structure around the Fermi level. In order to investigate the reactivity of graphene we expose graphene islands to a partial pressure of oxygen and following the evolution of the surface by STM during the exposure. For the exposure to air we removed the sample from the UHV chamber and we re-introduce it after several hours, taking STM images before and after. The surface areas not covered by the graphene islands present a dramatic change but the graphene structure, even the borders of the islands, remain intact. In the case of a complete graphene monolayer the exposure to oxygen or to air does not affect or destroy the rippled structure of the graphene monolayer.

  16. Ruthenocuprates RuSr2(Eu,Ce)2Cu2O10-y: Intrinsic magnetic multilayers

    Science.gov (United States)

    Živković, I.; Hirai, Y.; Frazer, B. H.; Prester, M.; Drobac, D.; Ariosa, D.; Berger, H.; Pavuna, D.; Margaritondo, G.; Felner, I.; Onellion, M.

    2002-04-01

    We report ac susceptibility data on RuSr2(Eu,Ce)2Cu2O10-y (Ru-1222, Ce content x=0.5 and 1.0), RuSr2GdCu2O8 (Ru-1212), and SrRuO3. Both Ru-1222 (x=0.5, 1.0) sample types exhibit unexpected magnetic dynamics in low magnetic fields: logarithmic time relaxation, switching behavior, and ``inverted'' hysteresis loops. Neither Ru-1212 nor SrRuO3 exhibit such magnetic dynamics. The results are interpreted as evidence of the complex magnetic order in Ru-1222. We propose a specific multilayer model to explain the data, and note that superconductivity in the ruthenocuprate is compatible with both the presence and absence of the magnetic dynamics.

  17. A Spatially Detailed Model of Isometric Contraction Based on Competitive Binding of Troponin I Explains Cooperative Interactions between Tropomyosin and Crossbridges.

    Directory of Open Access Journals (Sweden)

    Sander Land

    2015-08-01

    Full Text Available Biophysical models of cardiac tension development provide a succinct representation of our understanding of force generation in the heart. The link between protein kinetics and interactions that gives rise to high cooperativity is not yet fully explained from experiments or previous biophysical models. We propose a biophysical ODE-based representation of cross-bridge (XB, tropomyosin and troponin within a contractile regulatory unit (RU to investigate the mechanisms behind cooperative activation, as well as the role of cooperativity in dynamic tension generation across different species. The model includes cooperative interactions between regulatory units (RU-RU, between crossbridges (XB-XB, as well more complex interactions between crossbridges and regulatory units (XB-RU interactions. For the steady-state force-calcium relationship, our framework predicts that: (1 XB-RU effects are key in shifting the half-activation value of the force-calcium relationship towards lower [Ca(2+], but have only small effects on cooperativity. (2 XB-XB effects approximately double the duty ratio of myosin, but do not significantly affect cooperativity. (3 RU-RU effects derived from the long-range action of tropomyosin are a major factor in cooperative activation, with each additional unblocked RU increasing the rate of additional RU's unblocking. (4 Myosin affinity for short (1-4 RU unblocked stretches of actin of is very low, and the resulting suppression of force at low [Ca(2+] is a major contributor in the biphasic force-calcium relationship. We also reproduce isometric tension development across mouse, rat and human at physiological temperature and pacing rate, and conclude that species differences require only changes in myosin affinity and troponin I/troponin C affinity. Furthermore, we show that the calcium dependence of the rate of tension redevelopment k(tr is explained by transient blocking of RU's by a temporary decrease in XB-RU effects.

  18. Orientation-Dependent Oxygen Evolution on RuO2 without Lattice Exchange

    DEFF Research Database (Denmark)

    Stoerzinger, Kelsey A.; Diaz-Morales, Oscar; Kolb, Manuel

    2017-01-01

    RuO2 catalysts exhibit record activities toward the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the poten......RuO2 catalysts exhibit record activities toward the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess...... work, suggesting lattice oxygen is not exchanged in catalyzing OER on crystalline RuO2 surfaces. This hypothesis is supported by the correlation of activity with the number of active Ru-sites calculated by density functional theory, where more active facets bind oxygen more weakly. This new...

  19. Pt-Ru Catalysts Prepared by a Modified Polyol Process for Direct Methanol Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Junmin; ZHU Fangfang; ZHANG Kunhua; LIU Weiping; GUAN Weiming

    2012-01-01

    Supported PtRu/C catalysts used in direct methanol fuel cells (DMFCs) were prepared by a new modified polyol method.Transmission electron microscopy (TEM),X-ray diffraction (XRD) and cyclic voltammograms (CVs) were carried out to characterize the morphology,composition and the electrochemical properties of the PtRu/C catalyst.The results revealed that the PtRu nanoparticles with small average particle size (≈2.5 nm),and highly dispersed on the carbon support.The PtRu/C catalyst exhibited high catalytic activity and anti-poisoned performance than that of the JM PtRu/C.It is imply that the modified polyol method is efficient for PtRu/C catalyst preparation.

  20. Observation of vortex coalescence in the anisotropic spin-triplet superconductor Sr2RuO4.

    Science.gov (United States)

    Dolocan, V O; Veauvy, C; Servant, F; Lejay, P; Hasselbach, K; Liu, Y; Mailly, D

    2005-08-26

    We present direct imaging of magnetic flux structures over the ab face of the anisotropic, spin-triplet superconductor Sr2RuO4 using a scanning microSQUID force microscope. Individual vortices with a single flux quantum were observed at low magnetic fields applied along the out-of-pane direction. At intermediate fields, the direct imaging revealed coalescing of vortices and the formation of flux domains. Our observations imply the existence of a mechanism in this material for bringing vortices together overcoming the conventional repulsive vortex-vortex interaction.

  1. Comparison of Two Preparation Methods on Catalytic Activity and Selectivity of Ru-Mo/HZSM5 for Methane Dehydroaromatization

    Directory of Open Access Journals (Sweden)

    Lucia M. Petkovic

    2014-01-01

    Full Text Available Catalytic performance of Mo/HZSM5 and Ru-Mo/HZSM5 catalysts prepared by vaporization-deposition of molybdenum trioxide and impregnation with ammonium heptamolybdate was analyzed in terms of catalyst activity and selectivity, nitrogen physisorption analyses, temperature-programmed oxidation of carbonaceous residues, and temperature-programmed reduction. Vaporization-deposition rendered the catalyst more selective to ethylene and coke than the catalyst prepared by impregnation. This result was assigned to lower interaction of molybdenum carbide with the zeolite acidic sites.

  2. Study of electronic structures of CeRu{sub 2}Si{sub 2} by LDA+U method

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Michi-To [Department of Condensed Matter Physics, Kobe University, 1-1, Rokkodai, Nada, Kobe 657-8501 (Japan)]. E-mail: michi@kobe-u.ac.jp; Harima, Hisatomo [Department of Condensed Matter Physics, Kobe University, 1-1, Rokkodai, Nada, Kobe 657-8501 (Japan)

    2007-03-15

    Electronic structures of CeRu{sub 2}Si{sub 2} are calculated by LDA+U method extended for magnetic system with strong spin-orbit interaction. The LDA+U method significantly improves the character of the ground state in the nonmagnetic state. The calculated electronic structures explain change of physical properties associated with metamagnetic transition. The Fermi surfaces after metamagnetic transition were reproduced well in this method, although the continuous change of electronic structure by metamagnetic transition is not described.

  3. RuPd, RuCo, PdCo and RuPdCo materials as candidates for cathode catalyzers in PEM fuel cells; Materiales RuPd, RuCo, PdCo y RuPdCo como candidatos a catalizadores catodicos en celdas de combustible tipo PEM

    Energy Technology Data Exchange (ETDEWEB)

    Leyva Noyola, Fatima; Solorza Feria, Omar [Centro de Investigacion y Estudios Superiores del IPN, Mexico, D.F. (Mexico)]. E-mail: fleyva@cinvestav.mx

    2009-09-15

    This work reports on the catalytic activity of RuPd, RuCo, PdCo and RuPdCo material for oxygen reduction reaction (ORR). These materials were synthesized using chemical reduction with NaBH{sub 4} as a reducing agent in THF, in ambient temperature and pressure conditions. The evaluation of the catalytic activity was done using cyclic voltamperometry (CV) and rotary disc electrode (RDE) in H{sub 2}SO{sub 4} 0.5 M. The kinetic results showed that the electrochemical reaction involves 4 electrons and the transfer of the first electron is the determinant stage. The values of {alpha}, i0 and the Tafel slope were very similar for the four materials studied, around 0.4, 5x10{sup -6} mA cm{sup -2} and 60 mV dec-1, respectively. Although these values are less than those reported for nanostructured platinum, they are better than those reported for other materials such as pure Pd, which enables them to be considered as cathode catalysts for a proton exchange membrane fuel cell. [Spanish] En este trabajo se reporta la actividad catalitica de los materiales RuPd, RuCo, PdCo y RuPdCo para la reaccion de reduccion de oxigeno (RRO). Estos materiales fueron sintetizados por el metodo de reduccion quimica, usando NaBH{sub 4} como agente reductor en THF, en condiciones de temperatura y presion ambiental. La evaluacion de la actividad catalitica fue realizada usando Voltamperometria Ciclica (VC) y Electrodo Disco Rotatorio (EDR) en H{sub 2}SO{sub 4} 0.5 M. Los resultados cineticos mostraron que la reaccion electroquimica procede por la via de 4 electrones y la etapa determinante es la transferencia del primer electron. Los valores de {alpha}, i0 y pendiente de Tafel fueron muy similares para los 4 materiales estudiados, siendo estos de alrededor de 0.4, 5x10{sup -6} mA cm{sup -2} y 60 mV dec{sup -1}, respectivamente. Sin embargo, aun cuando estos valores son menores que los reportados para platino nanoestructurado, son mejores que los reportados para otros materiales como el Pd puro

  4. Effects of Promoters on a Ru/Sepiolite Catalyst for Carbon Dioxide Methanation

    Institute of Scientific and Technical Information of China (English)

    Laitao Luo; Songjun Li; Yan Ouyang

    2003-01-01

    In this work, CO2 methanation has been investigated over Ru-based catalysts. The effects of promoters on the activity, selectivity and reduction properties of the Ru/sepiolite catalyst were analyzed by kinetic and thermodynamic methods. The catalysts were characterized by means of TPD, and the results revealed that the addition of Mo, Mn or Co improved the properties of the Ru/sepiolite catalyst.The effects of promoters could affect the change of enthalpy, entropy and chemical potential.

  5. Stability, structural, elastic and electronic properties of RuN polymorphs from first-principles calculations

    Science.gov (United States)

    Bannikov, V. V.; Shein, I. R.; Ivanovskii, A. L.

    2010-05-01

    First-principles FLAPW-GGA calculations for six possible polymorphs of ruthenium mononitride RuN indicate that the most stable structure is that of zinc blende rather than the rock salt structure recently reported for synthesized RuN samples. The elastic, electronic properties and the features of chemical bonds of zinc-blende RuN polymorph were investigated and discussed in detail.

  6. Phototoxicity of strained Ru(ii) complexes: is it the metal complex or the dissociating ligand?

    Science.gov (United States)

    Azar, Daniel F; Audi, Hassib; Farhat, Stephanie; El-Sibai, Mirvat; Abi-Habib, Ralph J; Khnayzer, Rony S

    2017-07-27

    A photochemically dissociating ligand in Ru(bpy)2(dmphen)Cl2 [bpy = 2,2'-bipyridine; dmphen = 2,9-dimethyl-1,10-phenanthroline] was found to be more cytotoxic on the ML-2 Acute Myeloid Leukemia cell line than Ru(bpy)2(H2O)2(2+) and prototypical cisplatin. Our findings illustrate the potential potency of diimine ligands in photoactivatable Ru(ii) complexes.

  7. A Novel Ultrafine Ru-B Amorphous Alloy Catalyst for Glucose Hydrogenation to Sorbitol

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An ultrafine Ru-B amorphous alloy catalyst was prepared by chemical reduction with KBH4 in aqueous solution, which exhibited perfect selectivity to sorbitol (~100%) and very high activity during the liquid phase glucose hydrogenation, much higher than the corresponding crystallized Ru-B, the pure Ru powder, and Raney Ni catalysts. The correlation of the catalytic activity to both the structural and surface electronic characteristics was discussed briefly.

  8. Enantioselective light switch effect of Δ- and Λ-[Ru(phenanthroline)2 dipyrido[3,2-a:2', 3'-c]phenazine](2+) bound to G-quadruplex DNA.

    Science.gov (United States)

    Park, Jin Ha; Lee, Hyun Suk; Jang, Myung Duk; Han, Sung Wook; Kim, Seog K; Lee, Young-Ae

    2017-07-04

    The interaction of Δ- and Λ-[Ru(phen)2DPPZ](2+) (DPPZ = dipyrido[3,2-a:2', 3'-c]phenazine, phen = phenanthroline) with a G-quadruplex formed from 5'-G2T2G2TGTG2T2G2-3'(15-mer) was investigated. The well-known enhancement of luminescence intensity (the 'light-switch' effect) was observed for the [Ru(phen)2DPPZ](2+) complexes upon formation of an adduct with the G-quadruplex. The emission intensity of the G-quadruplex-bound Λ-isomer was 3-fold larger than that of the Δ-isomer when bound to the G-quadruplex, which is opposite of the result observed in the case of double stranded DNA (dsDNA); the light switch effect is larger for the dsDNA-bound Δ-isomer. In the job plot of the G-quadruplex with Δ- and Λ-[Ru(phen)2DPPZ](2+), a major inflection point for the two isomers was observed at x ≈ .65, which suggests a binding stoichiometry of 2:1 for both enantiomers. When the G base at the 8th position was replaced with 6-methyl isoxanthopterin (6MI), a fluorescent guanine analog, the excited energy of 6-MI transferred to bound Δ- or Λ-[Ru(phen)2DPPZ](2+), which suggests that at least a part of both Ru(II) enantiomers is close to or in contact with the diagonal loop of the G-quadruplex. A luminescence quenching experiment using [Fe(CN)6](4-) for the G-quadruplex-bound Ru(II) complex revealed downward bending curves for both enantiomers in the Stern-Volmer plot, which suggests the presence of Ru(II) complexes that are both accessible and inaccessible to the quencher and may be related to the 2:1 binding stoichiometry.

  9. Spontaneous deposition of Ru on Pt (100: morphological and electrochemical studies. Preliminary results of ethanol oxidation at Pt(100/Ru

    Directory of Open Access Journals (Sweden)

    Colle Vinicius D.

    2003-01-01

    Full Text Available In the present work ruthenium was deposited in submonolayer amounts on Pt(100 by spontaneous deposition at several deposition times. The Pt (100/Ru surfaces were analyzed using ex-situ STM to image the deposits characteristic of ruthenium on Pt (100. It was observed the formation of ruthenium islands with diameters between 1.0 and 4.5 nm with bi-atomic thickness in the center of the islands. A homogeneous distribution of the ruthenium islands on the platinum terraces was found, with no preferential deposition on steps or surface defect sites. The ruthenium coverage degree had been calculated by the decrease of charge of the hydrogen adsorption-desorption peaks in the cyclic voltammograms of the Pt(100/Ru electrodes. The Pt(100/Ru electrodes with a ruthenium coverage degree of ca. 0.3 showed a high activity for the ethanol electrooxidation. The electrochemical experimental results support strongly the bifunctional mechanism for the enhanced ethanol oxidation.

  10. Anomalous magnetic fluctuations in superconducting Sr2RuO4 revealed by 101Ru nuclear spin-spin relaxation

    Science.gov (United States)

    Manago, Masahiro; Yamanaka, Takayoshi; Ishida, Kenji; Mao, Zhiqiang; Maeno, Yoshiteru

    2016-10-01

    We carried out 101Ru nuclear quadrupole resonance (NQR) measurement on superconducting (SC) Sr2RuO4 under zero magnetic field (H =0 ) and found that the nuclear spin-spin relaxation rate 1 /T2 is enhanced in the SC state. The 1 /T2 measurement in the SC state under H =0 is effective for detecting slow magnetic fluctuations parallel to the quantized axis of the nuclear spin. Our results indicate that low-energy magnetic fluctuations perpendicular to the RuO2 plane emerge when the superconductivity sets in, which is consistent with the previous 17O-NQR result that the nuclear spin-lattice relaxation rate 1 /T1 of the in-plane O site exhibits anomalous behavior in the SC state. The enhancement of the magnetic fluctuations in the SC state is unusual and suggests that the fluctuations are related to the unconventional SC pairing. We suggest that this phenomenon is a consequence of the spin degrees of freedom of the spin-triplet pairing.

  11. Triaxial shapes in the ground states of even-even neutron-rich Ru isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    Partial level schemes for {sup 108,110,112}Ru, and {sup 114}Ru about which nothing was previously known, were determined from the measurement of prompt, triple-gamma coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 249}Cm source, mixed with 65-mg KCl and pressed in the form of a 7-mm diameter pellet, was used for the experiment. Prompt {gamma} rays emitted from the fission fragments were detected with the Eurogam array at Daresbury, which at that time consisted of 45 Compton suppressed Ge detectors and 5 LEPS spectrometers. Transitions in Ru were identified by gating on {gamma} rays in the complementary Te fragments. Figure I-25 shows the technique used to identify the previously unknown transitions in {sup 114}Ru and its partial level scheme. High spin states up to spin 10 h were observed and the {gamma}-ray branching ratios were determined. The ratios of electric quadrupole transition probabilities deduced from the experimental branching ratios were found to be in good agreement with the predictions of a simple model of rigid triaxial rotor. Our analysis shows that gamma deformation in Ru isotopes is increasing with the neutron number and the gamma value for {sup 112}Ru and {sup 114}Ru is {approximately} 25 degrees. This is one of the highest gamma values encountered in nuclei, suggesting soft triaxial shapes for {sup 112}Ru and {sup 114}Ru. The results of this investigation were published.

  12. Thermal stability of RuO sub 2 -based bottom electrodes during various ambient annealings

    CERN Document Server

    Ahn, J H; Choi, G P; Choi, W Y; Kim, H G; Lee, W J; Yoon, S G

    1999-01-01

    RuO sub 2 thin films were prepared on SiO sub 2 /Si, TiN/SiO sub 2 /Si and Ru/poly-Si by using DC magnetron sputtering. The annealing of the RuO sub 2 -based bottom electrodes was performed in oxygen and argon ambients and in high vacuum in the temperature range of 400 .deg. C approx 800 .deg. C. In oxygen-ambient annealing, the surface morphology was drastically changed due to the evaporation of ruthenium dioxides in the form of RuO sub 3 and RuO sub 4. The RuO sub 2 thin film annealed in high vacuum was reduced to the Ru metal phase. Evaporation and reduction of the RuO sub 2 thin films could actually be observed during the deposition of (Ba,Sr)TiO sub 3 thin films. oxygen diffusion through the RuO sub 2 /diffusion barrier/poly-Si structures is also discussed

  13. Magnetic properties and spin polarization of Ru doped half metallic CrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    West, Kevin G.; Dao, Nam N. H.; Lu, Jiwei, E-mail: jl5tk@virginia.edu [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Osofsky, Michael; Mazin, I. I. [Naval Research Laboratory, Washington, DC 20375 (United States); Wolf, Stuart A. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Department of Physics, University of Virginia, Charlottesville, Virginia 22904 (United States)

    2015-07-06

    Chromium dioxide (CrO{sub 2}) is a half metal that is of interest for spintronic devices. It has not been synthesized through traditional physical vapor deposition (PVD) techniques because of its thermodynamic instability in low oxygen pressures. Epitaxial thin films of Ru doped tetragonal rutile CrO{sub 2} were synthesized by a PVD technique. The as-deposited Ru{sub x}Cr{sub 1−x}O{sub 2} was ferrimagnetic with the saturation magnetization moment showing a strong dependence on the Ru concentration. Curie temperature as high as 241 K has been obtained for ∼23 at. % Ru. The Ru substitution increased the electrical conductivity by increasing the minority spin concentration. The spin polarization was found to be as high as 70% for 9 at. % Ru and decreased to ∼60% with Ru concentrations up to ∼44 at. %, which is determined by the Fermi velocities of the majority and minority spins. First principle calculations were performed to understand the effect of Ru content on the properties of CrO{sub 2}. The PVD processes of Ru doped CrO{sub 2} could lead to the practical applications of the high spin polarization of CrO{sub 2} in spintronic devices.

  14. Phase diagrams of Ca(Fe,Ru){sub 2}As{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Kan; Gegenwart, Philipp [Experimentalphysik VI, Elektronische Korrelationen und Magnetismus, Institut fuer Physik, Universitaet Augsburg, D-86135 Augsburg (Germany)

    2015-07-01

    Single crystalline Ca(Fe,Ru){sub 2}As{sub 2} series have been grown and characterized by structural, magnetic, and transport measurements. These measurement shows Ca(Fe,Ru){sub 2}As{sub 2} undergoes successive phase transitions with increasing Ru element doping. The antiferromagnetic phase with orthorhombic structure at x<0.023 (x means the doping concentration of Ru element) is directly driven to a Fermi-liquid type collapsed tetragonal (cT) phase at 0.023

  15. Characterization of a trinuclear ruthenium species in catalytic water oxidation by Ru(bda)(pic)2 in neutral media.

    Science.gov (United States)

    Zhang, Biaobiao; Li, Fei; Zhang, Rong; Ma, Chengbing; Chen, Lin; Sun, Licheng

    2016-06-30

    A Ru(III)-O-Ru(IV)-O-Ru(III) type trinuclear species was crystallographically characterized in water oxidation by Ru(bda)(pic)2 (H2bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; pic = 4-picoline) under neutral conditions. The formation of a ruthenium trimer due to the reaction of Ru(IV)[double bond, length as m-dash]O with Ru(II)-OH2 was fully confirmed by chemical, electrochemical and photochemical methods. Since the oxidation of the trimer was proposed to lead to catalyst decomposition, the photocatalytic water oxidation activity was rationally improved by the suppression of the formation of the trimer.

  16. Magnetic, thermal and transport properties of Tb{sub 3}Ru{sub 4}Al{sub 12} with a distorted kagome lattice

    Energy Technology Data Exchange (ETDEWEB)

    Gorbunov, D.I., E-mail: gorbunov@fzu.cz [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Henriques, M.S. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); CCTN, IST/CFMCUL, University of Lisbon, Nuclear and Technological Campus, P-2695-066 Bobadela (Portugal); Andreev, A.V. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Skourski, Y. [Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden (Germany); Dušek, M. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic)

    2015-06-15

    Highlights: • In hexagonal Tb{sub 3}Ru{sub 4}Al{sub 12} the Tb atoms reside in distorted kagome nets. • Tb{sub 3}Ru{sub 4}Al{sub 12} has an antiferromagnetic ground state. • Tb{sub 3}Ru{sub 4}Al{sub 12} displays field-induced phase transitions along all crystallographic axes. • The transitions are accompanied by large negative magnetoresistance. - Abstract: The Tb{sub 3}Ru{sub 4}Al{sub 12} compound (hexagonal crystal structure) having a distorted kagome net of the Tb atoms is studied on a single crystal by measurements of magnetization, specific heat and electrical resistivity. The system is an antiferromagnet with the Néel temperature T{sub N} = 22 K. A substantial magnetic anisotropy is observed that persists at least up to 60 T. Tb{sub 3}Ru{sub 4}Al{sub 12} displays field-induced magnetic phase transitions: one along [1 0 0] and [1 2 0] and two along the [0 0 1] axis. The transitions are accompanied by sharp peaks in magnetoresistance and subsequently lead to a large negative effect in it, −20% in the longitudinal and −40% in the transverse geometry. The peaks are explained by changes in conduction electron spectra at the transitions due to the interaction between the conduction electrons and localized magnetic moments. The large negative effect suggests field-induced magnetic phases with a reduced period as compared to zero field.

  17. Transport properties of Heusler compounds Ru{sub 2}CrGe and Ru{sub 2}CrSn under high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Okada, H; Koyama, K; Watanabe, K [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Sendai (Japan); Kusakari, Y; Kanomata, T [Faculty of Engineering, Tohoku Gakuin University, Tagajo (Japan); Matsuoka, E; Onodera, H, E-mail: hironari@imr.tohoku.ac.j [Department of Physics, Graduate School of Science, Sendai (Japan)

    2009-03-01

    We have performed the specific heat and the electrical resistivity measurements under high magnetic fields for Heusler compounds Ru{sub 2}CrGe and Ru{sub 2}CrSn. We found that the electrical resistivity for Ru{sub 2}CrGe shows an upturn in the vicinity of 130 K and changes a metallic to a semiconducting-like behavior with decreasing temperature. By applying magnetic field, a negative magnetoresistance was observed below 200 K. On the other hand, the electrical resistivity for Ru{sub 2}CrSn shows a semimetallic-like behavior. The results of the electrical resistivity in Ru{sub 2}CrGe suggest that the compound has a gap-like structure in the electronic structure at the Fermi level. Moreover, it was found that another phase transition occurs in Ru{sub 2}CrGe and Ru{sub 2}CrSn, in addition to the magnetic transition.

  18. Targeting human telomeric G-quadruplex DNA and inhibition of telomerase activity with [(dmb2Ru(obipRu(dmb2](4+.

    Directory of Open Access Journals (Sweden)

    Shuo Shi

    Full Text Available Inhibition of telomerase by inducing/stabilizing G-quadruplex formation is a promising strategy to design new anticancer drugs. We synthesized and characterized a new dinuclear complex [(dmb2Ru(obipRu(dmb2](4+ (dmb = 4,4'-dimethyl-2,2'-bipyridine, obip = (2-(2-pyridylimidazo[4,5-f][1,10]phenanthroline with high affinity for both antiparallel and mixed parallel / antiparallel G-quadruplex DNA. This complex can promote the formation and stabilize G-quadruplex DNA. Dialysis and TRAP experiments indicated that [(dmb2Ru(obipRu(dmb2](4+ acted as an excellent telomerase inhibitor due to its obvious selectivity for G-quadruplex DNA rather than double stranded DNA. In vitro co-culture experiments implied that [(dmb2Ru(obipRu(dmb2](4+ inhibited telomerase activity and hindered cancer cell proliferation without side effects to normal fibroblast cells. TUNEL assay indicated that inhibition of telomerase activity induced DNA cleavage further apoptosis in cancer cells. Therefore, Ru(II complex represents an exciting opportunity for anticancer drug design by specifically targeting cancer cell G-quadruplexes DNA.

  19. Ne2 encodes protein(s) and the altered RuBisCO could be the proteomics leader of hybrid necrosis in wheat (Triticum aestivum L.)

    Indian Academy of Sciences (India)

    SI RUI PAN; XING LAI PAN; QIANYING PAN; YIN HONG SHI; LI ZHANG; YUN FAN; YAN RUI XUE

    2017-06-01

    Wheat hybrid necrosis is caused by the interaction of two dominant complementary genes, Ne1 and Ne2, located on chromosome arms 5BL and 2BS, respectively. The sequences of Ne1 or Ne2 have not yet been identified. It is also not known whether Ne1 and Ne2 are structural or regulatory genes. Understanding the proteomic pathways may provide a knowledge base for protecting or maximizing the photosynthesis capacity of wheat. Using DIGE and MALDITOF-TOF MS, the flag leaf protein patterns of the two unique F14 near-isogenic line siblings (NILs), the necrotic ShunMai 12Ah (Ne1Ne1Ne2Ne2) and the normal ShunMai 12Af (Ne1Ne1ne2ne2) were compared. Due to the presence or absence of Ne2, (i) three protein spots were expressed or disappeared, (ii) seven RuBisCO-related proteins were altered significantly, and (iii) 21 photosynthesis/glucose related proteins were changed significantly. Three hypotheses were deduced, (i) Ne1 may also encode protein(s), (ii) genetic maladjustment of RuBisCO could lead to early leaf death, and (iii) interactions between nuclear genes and chloroplast genes could determine photosynthetic traits. Our hypothetical model presents the RuBisCO pathway of hybrid necrosis in wheat and explains how Ne1 and Ne2 interact at molecular level.

  20. Fabrication of ultra-thin cerium oxide layers on Ru(0001) single crystal surfaces. Scanning tunneling microscopic and photoelectron spectroscopic studies on growth, structure and properties; Herstellung ultraduenner Ceroxidschichten auf Ru(0001)-Einkristallflaechen. Rastertunnelmikroskopische und photoelektronenspektroskopische Untersuchungen zu Wachstum, Struktur und Eigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Bouchtaoui, Mustapha

    2016-12-07

    The thesis at hand aims at a study of structure and properties of well-defined ultrathin CeO{sub 2} films supported on Ru(0001). Such systems may serve as model systems in heterogenous catalysis. The epitaxial growth of ceria films on Ru(0001) surface has been achieved by electron beam evaporation of metal Cer at low background oxygen pressure of 10{sup -6} mbar under ultrahigh-vacuum conditions at room temperature. Cerium oxide qualifies for proper oxygen-storage in oxidation reactions, and hence it widely used in heterogenous catalysis. The oxidation begins with the adsorption of CO on the CeO{sub 2}(111) surface, and it ends with participation of lattice oxygen leading to vacancy formation and CO{sub 2} desorption. We investigate the geometric structure by means of scanning tunneling microscopy and low energy electron diffraction. The coverage of 2.5 monolayers (ML) was sufficient to cover the substrate almost completely. We further analysed the interaction of CO with the CeO{sub 2}/Ru(0001) and the Pt/CeO{sub 2}/Ru(0001) systems. During the interaction process the ratio of Ce{sup 4+} and Ce{sup 3+} changes significantly. This ratio change as well as the effect of Pt evaporated onto the surface with respect to the reducibility of CeO{sub 2}/Ru(0001) in CO environment has been studied by X-ray photoemission spectroscopy and it has been confirmed with thermal desorption spectroscopy. It is revealed that the Pt-Nanoparticles with a height from 7.15 Aa to 9.73 Aa clearly enhances the reducibility of CeO{sub 2}.

  1. Synthesis and unexpected reactivity of [Ru(6 -cymene)Cl2 (PPh2 Cl)], leading to [Ru(6 -cymene)Cl2 (PPh2H)] and [Ru(6-cymene)Cl2 (PPh2OH)] complexes

    Indian Academy of Sciences (India)

    Arun Kumar Pandiakumar; Ashoka G Samuelson

    2015-08-01

    The reaction of [Ru(6-cymene)Cl2]2 and PPh2Cl in the ratio 1:2 gives a stable [Ru(6-cymene) Cl2(PPh2Cl)] complex. Attempts to make the cationic [Ru(6-cymene)Cl(PPh2Cl)2]Cl with excess PPh2Cl and higher temperatures led to adventitious hydrolysis and formation of [Ru(6-cymene)Cl2 (PPh2OH)]. Attempts to make a phosphinite complex by reacting [Ru(6-cymene)Cl2]2 with PPh2Cl in the presence of an alcohol results in the reduction of PPh2Cl to give [Ru(6-cymene)Cl2(PPh2H)] and the expected phosphinite. The yield of the hydride complex is highest when the alcohol is 1-phenyl-ethane-1,2-diol. All three half-sandwich complexes are characterized by X-ray crystallography. Surprisingly, the conversion of chlorodiphenylphosphine to diphenylphosphine is mediated by 1-phenyl-ethane-1,2-diol even in the absence of the ruthenium half-sandwich precursor.

  2. Dissociative sticking of CH4 on Ru(0001)

    DEFF Research Database (Denmark)

    Nielsen, Jane Hvolbæk; Holmblad, Peter Mikal; Chorkendorff, Ib

    1999-01-01

    In this study the CH4 dissociation probability on Ru(0001) is found for various translational and vibrational energies. The absolute sticking values are determined from King and Wells experiments and carbon uptake curves. The carbon amount is determined from the recombination signal of carbon...... with oxygen obtained after the beam exposure when heating in an oxygen atmosphere. The measured sticking coefficient of CH4 is strongly enhanced both by increasing the translational and the vibrational energy of the CH4 molecule. A model is applied to the data and an estimate of the thermal activation energy...

  3. Triaxiality near the 110Ru ground state from Coulomb excitation

    Science.gov (United States)

    Doherty, D. T.; Allmond, J. M.; Janssens, R. V. F.; Korten, W.; Zhu, S.; Zielińska, M.; Radford, D. C.; Ayangeakaa, A. D.; Bucher, B.; Batchelder, J. C.; Beausang, C. W.; Campbell, C.; Carpenter, M. P.; Cline, D.; Crawford, H. L.; David, H. M.; Delaroche, J. P.; Dickerson, C.; Fallon, P.; Galindo-Uribarri, A.; Kondev, F. G.; Harker, J. L.; Hayes, A. B.; Hendricks, M.; Humby, P.; Girod, M.; Gross, C. J.; Klintefjord, M.; Kolos, K.; Lane, G. J.; Lauritsen, T.; Libert, J.; Macchiavelli, A. O.; Napiorkowski, P. J.; Padilla-Rodal, E.; Pardo, R. C.; Reviol, W.; Sarantites, D. G.; Savard, G.; Seweryniak, D.; Srebrny, J.; Varner, R.; Vondrasek, R.; Wiens, A.; Wilson, E.; Wood, J. L.; Wu, C. Y.

    2017-03-01

    A multi-step Coulomb excitation measurement with the GRETINA and CHICO2 detector arrays was carried out with a 430-MeV beam of the neutron-rich 110Ru (t1/2 = 12 s) isotope produced at the CARIBU facility. This represents the first successful measurement following the post-acceleration of an unstable isotope of a refractory element. The reduced transition probabilities obtained for levels near the ground state provide strong evidence for a triaxial shape; a conclusion confirmed by comparisons with the results of beyond-mean-field and triaxial rotor model calculations.

  4. Comparing Ru and Fe-catalyzed olefin metathesis

    KAUST Repository

    Poater, Albert

    2014-01-01

    Density functional theory calculations have been used to explore the potential of Fe-based complexes with an N-heterocyclic carbene ligand, as olefin metathesis catalysts. Apart from a less endothermic reaction energy profile, a small reduction in the predicted upper energy barriers (≈ 2 kcal mol -1) is calculated in the Fe catalyzed profile with respect to the Ru catalysed profile. Overall, this study indicates that Fe-based catalysts have the potential to be very effective olefin metathesis catalysts. This journal is © the Partner Organisations 2014.

  5. Is the methanation reaction over Ru single crystals structure dependent?

    DEFF Research Database (Denmark)

    Vendelbo, Søren Bastholm; Johansson, Martin; Nielsen, Jane Hvolbæk;

    2011-01-01

    The influence of monoatomic steps and defects on the methanation reaction over ruthenium has been investigated. The experiments are performed on a Ru(0 1 54) ruthenium single crystal, which contains one monoatomic step atom for each 27 terrace atoms. The methanation activity is measured at one ba...... front-side of the crystal is poisoned faster than the entire crystal containing more defects. We also observe that additional sputtering of the well-defined front-side increases the reactivity measured on the surface. Based on this, we conclude that the methanation reaction takes place...

  6. Extended collective bands in neutron-rich 109Ru

    Institute of Scientific and Technical Information of China (English)

    DING Huai-Bo; ZHU Sheng-Jiang; J.H. Hamilton; A.V. Ramayya; J. K. Hwang; K. Li; S.H. Liu; Y.X. Luo; J.O. Rasmussen; C.T. Goodin; I. Y. Lee; WANG Jian-Guo; CHE Xing-Lai; GU Long

    2009-01-01

    Levels in the neutron-rich 109Ru have been studied by observing the prompt γ-rays following the spontaneous fission fragments of 252Cf. The ground state band and the negative parity bands have been confirmed and extended. A positive parity band with the band head level at 332.5 keV is newly identified and suggested as a single-neutron excitation band built on the 7/2+ [404] Nilsson orbital. Some structural characteristics of these bands are discussed.

  7. THz-Pulse-Induced Selective Catalytic CO Oxidation on Ru

    Science.gov (United States)

    LaRue, Jerry L.; Katayama, Tetsuo; Lindenberg, Aaron; Fisher, Alan S.; Ã-ström, Henrik; Nilsson, Anders; Ogasawara, Hirohito

    2015-07-01

    We demonstrate the use of intense, quasi-half-cycle THz pulses, with an associated electric field component comparable to intramolecular electric fields, to direct the reaction coordinate of a chemical reaction by stimulating the nuclear motions of the reactants. Using a strong electric field from a THz pulse generated via coherent transition radiation from an ultrashort electron bunch, we present evidence that CO oxidation on Ru(0001) is selectively induced, while not promoting the thermally induced CO desorption process. The reaction is initiated by the motion of the O atoms on the surface driven by the electric field component of the THz pulse, rather than thermal heating of the surface.

  8. Investigation of Novel Electrocatalysts for Metal Supported Solid Oxide Fuel Cells - Ru:GDC

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Nielsen, Jimmy; Thydén, Karl Tor Sune

    2015-01-01

    The electrochemical performance and stability of the planar metal supported solid oxide fuel cells (MS-SOFC) with two different electrocatalytically active materials, namely, Ni:GDC and Ru:GDC were investigated. Ru:GDC with an ASR of 0.322 Ωcm2 performed better than Ni:GDC with an ASR of 0.453 Ωc...

  9. Lutidine-derived Ru-CNC hydrogenation pincer catalysts with versatile coordination properties

    NARCIS (Netherlands)

    Filonenko, Georgy A.; Cosimi, Elena; Lefort, Laurent; Conley, Matthew P.; Copéret, Christophe; Lutz, Martin|info:eu-repo/dai/nl/304828971; Hensen, Emiel J M; Pidko, Evgeny A.

    2014-01-01

    Lutidine-derived bis-N-heterocyclic carbene (NHC) ruthenium CNC-pincer complexes (Ru-CNC's) were prepared. Depending on the synthetic procedure, normal (1, 2) or mixed normal/abnormal NHC-complexes (3) are formed. In the presence of phosphazene base, Ru-CNC complexes activate nitriles to give ketimi

  10. A PHARMACOKINETIC STUDY ON RU 486 AND ITS METABOLITES AFTER ORAL ADMINISTRATION AT VARIOUS DOSES

    Institute of Scientific and Technical Information of China (English)

    SHIYong-En; YEZhi-Hou; HEChang-Hai; ZHANGGuo-Qin; XUJian-Qiu; BAJXiu-Mei

    1989-01-01

    The purpose of the present study is to obtain pharmacokinetic parameters of RU486 and its metabolites and then to find out an optimal regimen of the compound for termination of human early pregnancy. Plasma levels of RU486 and its metabolites,

  11. Lutidine-derived Ru-CNC hydrogenation pincer catalysts with versatile coordination properties

    NARCIS (Netherlands)

    Filonenko, Georgy A.; Cosimi, Elena; Lefort, Laurent; Conley, Matthew P.; Copéret, Christophe; Lutz, Martin; Hensen, Emiel J M; Pidko, Evgeny A.

    2014-01-01

    Lutidine-derived bis-N-heterocyclic carbene (NHC) ruthenium CNC-pincer complexes (Ru-CNC's) were prepared. Depending on the synthetic procedure, normal (1, 2) or mixed normal/abnormal NHC-complexes (3) are formed. In the presence of phosphazene base, Ru-CNC complexes activate nitriles to give ketimi

  12. Hydrothermal Synthesis of Co-Ru Alloy Particle Catalysts for Hydrogen Generation from Sodium Borohydride

    Directory of Open Access Journals (Sweden)

    Marija Kurtinaitienė

    2013-01-01

    Full Text Available We report the synthesis of μm and sub-μm-sized Co, Ru, and Co-Ru alloy species by hydrothermal approach in the aqueous alkaline solutions (pH ≥ 13 containing CoCl2 and/or RuCl3, sodium citrate, and hydrazine hydrate and a study of their catalytic properties for hydrogen generation by hydrolysis of sodium borohydride solution. This way provides a simple platform for fabrication of the ball-shaped Co-Ru alloy catalysts containing up to 12 wt% Ru. Note that bimetallic Co-Ru alloy bowls containing even 7 at.% Ru have demonstrated catalytic properties that are comparable with the ones of pure Ru particles fabricated by the same method. This result is of great importance in view of the preparation of cost-efficient catalysts for hydrogen generation from borohydrides. The morphology and composition of fabricated catalyst particles have been characterized using scanning electron microscopy, energy dispersive X-ray diffraction, and inductively coupled plasma optical emission spectrometry.

  13. Adsorption properties of CoPc molecule on epitaxial graphene/Ru(0 0 0 1)

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Yiliang; Zhang, Hanjie; Song, Junjie; Zhang, Yuxi; Bao, Shining; He, Pimo, E-mail: phypmhe@zju.edu.cn

    2015-02-01

    Graphical abstract: - Highlights: • The adsorption behavior of CoPc on MG/Ru(0 0 0 1) was investigated by STM and DFT. • The impact of the defect in MG/Ru(0 0 0 1) on the adsorption properties was studied. • A central contrast was found for CoPcs adsorbed on intact and defective graphene. - Abstract: Combining the scanning tunneling microscopy (STM) and density functional theory (DFT), the adsorption properties of cobalt phthalocyanine (CoPc) on monolayer graphene/Ru(0 0 0 1) [MG/Ru(0 0 0 1)] have been investigated. At monolayer coverage, CoPc forms an ordered Kagome lattice, and a slight deformation for one lobe of CoPc and charge transfer from CoPc to Ru(0 0 0 1) substrate take place. The existence of the defect (vacancy) in graphene on Ru(0 0 0 1) increases the coupling between the Ru substrate and the epitaxial graphene. Such an increase of the coupling brings about an overall CoPc molecular energy level shift toward the low binding energy, which subsequently results in a central topographical contrast between the CoPc molecules on the intact and defective MG/Ru(0 0 0 1)

  14. Superconductivity at 3.1 K in the orthorhombic ternary silicide ScRuSi

    Science.gov (United States)

    Ruan, Bin-Bin; Wang, Xiao-Chuan; Yu, Jia; Pan, Bo-Jin; Mu, Qing-Ge; Liu, Tong; Chen, Gen-Fu; Ren, Zhi-An

    2017-02-01

    We report the synthesis, crystal structure, superconductivity and physical property characterizations of the ternary equiatomic compound ScRuSi. Polycrystalline samples of ScRuSi were prepared by an arc-melting method. The as-prepared samples were identified as the orthorhombic Co2P-type o-ScRuSi by powder x-ray diffraction analysis. Electrical resistivity measurements show o-ScRuSi to be a metal which superconducts below a T c of 3.1 K; the upper critical field μ 0 H c2(0) is estimated to be 0.87 T. The magnetization and specific heat measurements confirm the bulk type-II superconductivity in o-ScRuSi, with a specific heat jump within the BCS weak coupling limit. o-ScRuSi is the first Co2P-type superconductor to contain scandium. After annealing at 1273 K for a week, o-ScRuSi transforms into hexagonal Fe2P-type h-ScRuSi, which is a Pauli-paramagnetic metal with no superconductivity observed above 1.8 K.

  15. PtRu colloid nanoparticles for CO oxidation in microfabricated reactors

    DEFF Research Database (Denmark)

    Klerke, Asbjørn; Saadi, Souheil; Toftegaard, Maja Bøg

    2006-01-01

    The catalytic activity of PtRu colloid nanoparticles for CO oxidation is investigated in microfabricated reactors. The measured catalytic performance describes a volcano curve as a function of the Pt/Ru ratio. The apparent activation energies for the different alloy catalysts are between 21 and 117...

  16. Ru alkylidene compounds bearing tridentate, dianionic ligands: Lewis acid activation and olefin metathesis.

    Science.gov (United States)

    McKinty, Adam M; Stephan, Douglas W

    2016-03-01

    The series of tridentate complexes of Ru-alkylidenes (L)Ru(CHPh)(SCH2CH2)2E (E = O, L = SIMes 1, PCy3 2, E = S, L = SIMes 3, PCy3 4; E = PPh 7, L = PCy3), (L)Ru(CHPh)(SC6H4)2S (L = SIMes 5, PCy3 6), (L)Ru(CHPh) (OCH2CH2)2O (L = SIMes 8, PCy3 9) were prepared and shown to react with one equivalent of BCl3 to give the complexes (L)Ru(CHPh)Cl[E(CH2CH2S)2BCl2] (E = O, L = SIMes 10, PCy3 11, E = S, L = SIMes 12a/b, PCy3 13, E = PPh, L = PCy3 16) and (L)Ru(CHPh)(SC6H4)2O (L = SIMes 14, PCy3 15). In the case of 1 and 2 reaction with two equivalents of BCl3 affording the corresponding cation via chloride abstraction. These cations coordinate MeCN to give the six coordinate Ru cation salts [(L)Ru(CHPh)- (NCMe)(O(CH2CH2S)2BCl2)][BCl4] L = SIMes 17, PCy3 18). The generated five coordinate cations derived from 2-9 via addition of two equivalents of BCl3 were evaluated in standard preliminary tests for olefin metathesis catalysis.

  17. The formation mechanism of bimetallic PtRu alloy nanoparticles in solvothermal synthesis.

    Science.gov (United States)

    Mi, Jian-Li; Nørby, Peter; Bremholm, Martin; Becker, Jacob; Iversen, Bo B

    2015-10-21

    An understanding of the nucleation and growth mechanism of bimetallic nanoparticles in solvothermal synthesis is important for further development of nanoparticles with tailored nanostructures and properties. Here the formation of PtRu alloy nanoparticles in a solvothermal synthesis using metal acetylacetonate salts as precursors and ethanol as both the solvent and reducing agent has been studied by in situ synchrotron radiation powder X-ray diffraction (SR-PXRD). Unlike the classical mechanism for the synthesis of monodisperse sols, the nucleation and growth processes of bimetallic PtRu nanoparticles occur simultaneously under solvothermal conditions. In the literature co-reduction of Pt and Ru is often assumed to be required to form PtRu bimetallic nanocrystals, but it is shown that monometallic Pt nanocrystals nucleate first and rapidly grow to an average size of 5 nm. Subsequently, the PtRu bimetallic alloy is formed in the second nucleation stage through a surface nucleation mechanism related to the reduction of Ru. The calculated average crystallite size of the resulting PtRu nanocrystals is smaller than that of the primary Pt nanocrystals due to the large disorder in the PtRu alloyed structure.

  18. Lutidine-derived Ru-CNC hydrogenation pincer catalysts with versatile coordination properties

    NARCIS (Netherlands)

    Filonenko, Georgy A.; Cosimi, Elena; Lefort, Laurent; Conley, Matthew P.; Copéret, Christophe; Lutz, Martin|info:eu-repo/dai/nl/304828971; Hensen, Emiel J M; Pidko, Evgeny A.

    2014-01-01

    Lutidine-derived bis-N-heterocyclic carbene (NHC) ruthenium CNC-pincer complexes (Ru-CNC's) were prepared. Depending on the synthetic procedure, normal (1, 2) or mixed normal/abnormal NHC-complexes (3) are formed. In the presence of phosphazene base, Ru-CNC complexes activate nitriles to give

  19. Electrocatalytic activity of atomic layer deposited Pt–Ru catalysts onto N-doped carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Anne-Charlotte Elisabeth Birgitta; Larsen, Jackie Vincent; Verheijen, Marcel A.

    2014-01-01

    (ethylcyclopentadienyl)ruthenium (Ru(EtCp)2), respectively. O2 was used as the reactant in both processes. The composition of the catalysts was easily tuned by varying the Pt-to-Ru ALD cycle ratio. The catalysts were tested toward the CO oxidation and methanol oxidation reaction (MOR) in a three-electrode electrochemical set...

  20. EFFECT OF RU486 ON THE LUTEAL FUNCTION IN THE PREGNANT MOUSE

    Institute of Scientific and Technical Information of China (English)

    LIShu-Xiang; GUDun-Yu; WUXiao-Yun; ZHUJian-Yu; JIANGWen-Jue; SUNPei-Long; YANGYi-Qian

    1989-01-01

    The effect of RU486, an antiprogestin, on luteal functions in the post-implantation mouse was studied. (1) In vivo experiment: Female adult mice were treated with RU486 at an oral dose of 100 mg/kg on day 1 and day 2 of pregnancy. Autopsy was performed

  1. RuO2 pH Sensor with Super-Glue-Inspired Reference Electrode

    National Research Council Canada - National Science Library

    Wade Lonsdale; Magdalena Wajrak; Kamal Alameh

    2017-01-01

    A pH-sensitive RuO2 electrode coated in a commercial cyanoacrylate adhesive typically exhibits very low pH sensitivity, and could be paired with a RuO2 working electrode as a differential type pH sensor...

  2. Photoluminescence quenching of [Ru(bpy)2(atatp)](2+) bound to a condensed DNA matrix.

    Science.gov (United States)

    Chen, Linlin; Chao, Hui; Zhao, Qianwen; Zheng, Xuling; Li, Hong

    2016-01-01

    A novel [Ru(bpy)2(atatp)](2+) (bpy=2,2'-bipyridine and atatp=acenaphtheno[1,2-b]-1,4,8,9-tetraazatriphenylene) can induce the condensation of herring sperm DNA to form an orange-red cast film via intercalation and electrostatic attraction. The thus-prepared cast film shows microsecond emission lifetimes and reversible luminescence tuning characteristics by oxygen and nitrogen with an on-off emission intensity ratio of 4.3. The photoluminescence of [Ru(bpy)2(atatp)](2+) bound to a DNA condensed matrix can be quenched by water, dissolved oxygen, copper(II) and ferrocyanide ions. The DNA binding is found to hardly alter the dynamic quenching of [Ru(bpy)2(atatp)](2+) by oxygen at a low DNA-to-Ru(II) molar ratio (r=0.83), allowing [Ru(bpy)2(atatp)](2+) to keep a basically unchanged oxygen quenching constant, as well as endow the photo-induced electron transfer between [Ru(bpy)2(atatp)](2+) and copper(II) cations, and weaken the electrostatic attraction of [Ru(bpy)2(atatp)](2+) with ferrocyanide anions. In addition, the DNA condensation induced by [Ru(bpy)2(atatp)](2+) can protect the DNA oxidative damage against superoxide anion and hydroxyl radical toxicity. The present results could provide a versatile platform for better fabrication of optoelectronic devices.

  3. Anisotropic Ru3 + 4 d5 magnetism in the α -RuCl3 honeycomb system: Susceptibility, specific heat, and zero-field NMR

    Science.gov (United States)

    Majumder, M.; Schmidt, M.; Rosner, H.; Tsirlin, A. A.; Yasuoka, H.; Baenitz, M.

    2015-05-01

    Hexagonal α -Ru trichloride single crystals exhibit a strong magnetic anisotropy and we show that upon applying fields up to 14 T in the honeycomb plane the successive magnetic order at T1=14 K and T2=8 K could be completely suppressed, whereas in the perpendicular direction the magnetic order is robust. Furthermore, the field dependence of χ (T ) implies coexisting ferro- and antiferromagnetic exchange between in-plane components of Ru3+ spins, whereas for out-of-plane components a strong antiferromagnetic exchange becomes evident. 101Ru zero-field nuclear magnetic resonance in the ordered state evidence a complex (probably noncoplanar chiral) long-range magnetic structure. The large orbital moment on Ru3 + is found in density-functional calculations.

  4. Low leakage Ru-strontium titanate-Ru metal-insulator-metal capacitors for sub-20 nm technology node in dynamic random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Popovici, M., E-mail: Mihaela.Ioana.Popovici@imec.be; Swerts, J.; Redolfi, A.; Kaczer, B.; Aoulaiche, M.; Radu, I.; Clima, S.; Everaert, J.-L.; Van Elshocht, S.; Jurczak, M. [Imec, Leuven 3001 (Belgium)

    2014-02-24

    Improved metal-insulator-metal capacitor (MIMCAP) stacks with strontium titanate (STO) as dielectric sandwiched between Ru as top and bottom electrode are shown. The Ru/STO/Ru stack demonstrates clearly its potential to reach sub-20 nm technology nodes for dynamic random access memory. Downscaling of the equivalent oxide thickness, leakage current density (J{sub g}) of the MIMCAPs, and physical thickness of the STO have been realized by control of the Sr/Ti ratio and grain size using a heterogeneous TiO{sub 2}/STO based nanolaminate stack deposition and a two-step crystallization anneal. Replacement of TiN with Ru as both top and bottom electrodes reduces the amount of electrically active defects and is essential to achieve a low leakage current in the MIM capacitor.

  5. Highly (110)- and (111)-oriented BiFeO3 films on BaPbO3 electrode with Ru or Pt /Ru barrier layers

    Science.gov (United States)

    Lee, Chia-Ching; Wu, Jenn-Ming; Hsiung, Chang-Po

    2007-04-01

    Highly (110)- and (111)-oriented BiFeO3 (BFO) films were fabricated with BaPbO3 (BPO )/Ru and BPO /Pt/Ru as electrode/barrier on Si substrates by rf-magnetron sputtering. The BPO /Ru and BPO /Pt/Ru stacks both induce oriented BFO films and act as diffusion barriers. The (110)- and (111)-oriented BFO films possess excellent ferroelectric properties with only minor leakage. The values of remnant polarization are almost the same, about 42μC/cm2, for (110)- and (111)-oriented BFO films. However, polarization measured under varying pulse widths demonstrates that the switching polarization in (111)-oriented BFO films is higher than in (110)-oriented films. Additionally, (111)-oriented BFO films exhibit better retention properties than (110)-oriented films.

  6. RuO2/Ru/TiO2光催化剂制备及模拟太阳光催化产氢

    Institute of Scientific and Technical Information of China (English)

    刘海波; 阎建辉

    2009-01-01

    采用浸渍-氢气还原法制备了RuO2/Ru/TiO2光催化剂,并采用XRD、SEM、UV-vis漫反射光谱和荧光光谱(FS)等手段对样品进行了表征,以草酸为电子给体,研究了RuO2的负载量对P25-TiO2光催化产氢活性的影响。结果表明,P25-TiO2表面负载RuO2大大地提高了其光催化产氢速度,模拟太阳光下2wt%负载量下达到最佳产氢活性,6h内的产氢量达到45mmol。

  7. Angle-integrated photoemission studies of ruthocuprate Eu_2-xCe_xRuSr_2Cu_2O_10, Gd_2RuSr_2Cu_2O_10 and Eu_1.5Nb_1-xRu_xCu_2O_10 systems

    Science.gov (United States)

    Frazer, B.; Hirai, Y.; Rast, Simon; Felner, I.; Asaf, U.; Onellion, M.

    2000-03-01

    We report on both resonant photoemission and fixed photon energy studies of the conduction band and core levels for several ruthocuprate systems. The pure Ru-containing compounds exhibit ferromagnetic order, with metallic behavior and superconductivity depending on the rare earth and oxygen content. We report on as-prepared, hydrogen loaded, and oxygen-annealed polycrystalline samples. The Nb-Ru series changes from purely superconducting to both ferromagnetic and superconducting (Ru). The resonant photoemission measurements of the conduction band across the Ru4p, Cu3p, and Eu4d core levels allow us to determine the location and contribution of Ru, Cu and rare earth related states in the conduction band. The O1s, Cu2p, Ru3p, Ce4d, and Gd4d and several Nb core levels allow us to determine the valence of Ru and Nb, and the metallicity of the Ru/Nb, rare earth, and CuO2 planes.

  8. Particle Size Effect of Ru-Zn Catalysts on Selective Hydrogenation of Benzene to Cyclohexene†%Ru-Zn 催化剂在苯选择加氢制环己烯反应中的粒径效应

    Institute of Scientific and Technical Information of China (English)

    孙海杰; 陈凌霞; 黄振旭; 刘寿长; 刘仲毅

    2015-01-01

    Ru-Zn catalysts modified by water soluble polymers were prepared by a precipitation method. The catalysts after hydrogenation were characterized by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy and N2 physisorption. It was found that the type of water-soluble polymers and the dosage of PEG-20000 imposed a remarkable effect on the particle size of Ru. With the Ru particle size in Ru-Zn catalysts increasing, benzene conversion decreased, and the maximum cyclohexene yield showed a volcanic-type variation tendency. When the Ru particle size of the Ru-Zn catalyst modified by 0. 4 g PEG[ m( PEG-20000) : m( Ru) = 0. 2] was 4. 8 nm, a maximum cyclohexene yield of 62. 2% was obtained on this catalyst. The Ru particle size could produce an effect on the Zn / Ru atomic ratio on the catalyst surface, which was the primary reason why the Ru particle size could affect the performance of Ru-Zn catalysts.%采用共沉淀法制备了水溶性聚合物修饰的苯选择加氢制环己烯 Ru-Zn 催化剂,并用 X 射线衍射、透射电镜、 X 射线能量色散谱、 X 射线光电子能谱和氮气物理吸附等对加氢后催化剂进行了表征.结果表明,水溶性聚合物的种类和聚乙二醇-20000(PEG-20000)的用量对 Ru-Zn 催化剂微晶尺寸有显著影响.在 ZnSO4存在下,随着 Ru-Zn 催化剂 Ru 微晶尺寸增加,苯转化率降低,环己烯最高收率则呈火山型变化趋势.用0.4 g PEG-20000修饰的 Ru-Zn 催化剂[m(PEG-20000): m(Ru)=0.2]Ru 的微晶尺寸为4.8 nm,环己烯最高收率为62.2%. Ru 微晶尺寸影响催化剂表面的 Zn/ Ru 原子比,进而影响 Ru-Zn 催化剂性能.

  9. The influence of anionic ligands on stereoisomerism of Ru carbenes and their importance to efficiency and selectivity of catalytic olefin metathesis reactions.

    Science.gov (United States)

    Torker, Sebastian; Khan, R Kashif M; Hoveyda, Amir H

    2014-03-01

    Investigations detailed herein provide insight regarding the mechanism of stereochemical inversion of stereogenic-at-Ru carbene complexes through a nonolefin metathesis-based polytopal rearrangement pathway. Computational analyses (DFT) reveal that there are two key factors that generate sufficient energy barriers that are responsible for the possibility of isolation and characterization of high-energy, but kinetically stable, intermediates: (1) donor-donor interactions that involve the anionic ligands and the strongly electron donating carbene groups and (2) dipolar effects arising from the syn relationship between the anionic groups (iodide and phenoxide). We demonstrate that a Brønsted acid lowers barriers to facilitate isomerization, and that the positive influence of a proton source is the result of its ability to diminish the repulsive electronic interactions originating from the anionic ligands. The implications of the present studies regarding a more sophisticated knowledge of the role of anionic units on the efficiency of Ru-catalyzed olefin metathesis reactions are discussed. The electronic basis for the increased facility with which allylic alcohols participate in olefin metathesis processes will be presented as well. Finally, we illustrate how a better understanding of the role of anionic ligands has served as the basis for successful design of Ru-based Z-selective catalysts for alkene metathesis.

  10. Characterisation and catalytic properties of Ni, Co, Ce and Ru nanoparticles in mesoporous carbon spheres

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Francisco A. A. [Universidade Federal do Ceara, Departamento de Quimica Analitica e Fisico-Quimica, Langmuir Lab de Adsorcao e Catalise (Brazil); Castro, Antonio J. R.; Filho, Josue M. [Universidade Federal do Ceara, Departamento de Fisica (Brazil); Viana, Bartolomeu C. [Universidade Federal do Piaui, Departamento de Fisica (Brazil); Campos, Adriana [CETENE Av. Prof. Luiz Freire, Cidade Universitaria (Brazil); Oliveira, Alcineia C., E-mail: alcineia@ufc.br [Universidade Federal do Ceara, Departamento de Quimica Analitica e Fisico-Quimica, Langmuir Lab de Adsorcao e Catalise (Brazil)

    2012-09-15

    Ni, Co, Ce and Ru nanoparticles were inserted into templated carbon using a nanocasting technique and evaluated for the dehydration of glycerol. NiO and CeO{sub 2} preferentially yielded 5 nm uniformly sized particles that filled the mesoporous carbon via a geometric confinement effect. Ru generated Ru{sup o} and RuO{sub 2} nanoparticles that selectively migrated towards the carbon surface and did not undergo sintering, whereas Co nanoparticles containing CoO and Co{sub 3}O{sub 4} showed the opposite behaviour. The stabilising effects of the Ce and Ru nanoparticles on the carbon matrix effectively prevented the aggregation of small particles, resulting in superior catalytic performance in glycerol dehydration.

  11. Enhanced thermoelectric power and electronic correlations in RuSe2

    Science.gov (United States)

    Wang, Kefeng; Wang, Aifeng; Tomic, A.; Wang, Limin; Abeykoon, A. M. Milinda; Dooryhee, E.; Billinge, S. J. L.; Petrovic, C.

    2015-04-01

    We report the electronic structure, electric and thermal transport properties of Ru1-xIrxSe2 (x ≤ 0.2). RuSe2 is a semiconductor that crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe2 exceeds -200 μV/K around 730 K. Ir substitution results in the suppression of the resistivity and the Seebeck coefficient, suggesting the removal of the peaks in density of states near the Fermi level. Ru0.8Ir0.2Se2 shows a semiconductor-metal crossover at about 30 K. The magnetic field restores the semiconducting behavior. Our results indicate the importance of the electronic correlations in enhanced thermoelectricity of RuSb2.

  12. Halide-promoted reactions of alkynes with Ru sub 3 (CO) sub 12

    Energy Technology Data Exchange (ETDEWEB)

    Rivomanana, S.; Lavigne, G.; Lugan, N.; Bonnet, J.; Yanez, R.; Mathieu, R. (Universite Paul Sabatier, Toulouse (France))

    1989-11-22

    The promoter effect of anionic nucleophiles on reactions of metal carbonyl complexes is of high current interest. In particular, several novel catalytic processes of potential industrial relevance are based on Ru{sub 3}(CO){sub 12}/halide systems as catalyst precursors. The authors have found that the activated complex (PPN)(Ru{sub 3}({mu}-Cl)(CO){sub 10}) ((PPN)(3)), which is readily obtained from the initial halide adduct (PPN)(Ru{sub 3}({eta}{sup 1}-Cl)(CO){sub 11}) ((PPN)(2)) (PPN = bis(triphenylphosphine)iminium), reacts with alkynes at 25{degree}C in THF (reaction 1) to produce a labile species (PPN)(Ru{sub 3}({mu}-Cl)({mu}-{eta}{sup 2}-RCCR{prime})(CO){sub 9}) ((PPN)(4)) that serves as a convenient precursor to new and known alkyne-substituted derivatives of Ru{sub 3}(CO){sub 12}.

  13. A density functional theory study of propylene epoxidation on RuO2(110) surface

    Science.gov (United States)

    Atmaca, Deniz Onay; Düzenli, Derya; Ozbek, M. Olus; Onal, Isik

    2016-11-01

    Propylene epoxidation is investigated on RuO2(110) and oxygen added RuO2-Oot(110) surfaces by periodic DFT computational method. The desired product propylene oxide (PO) as well as the undesired products acetone (AC) or propionaldehyde (PA) form on both surfaces through either surface intermediate oxometallopropylene (OMMP) or direct oxygen insertion mechanisms. On RuO2(110) surface, nucleophilic lattice oxygen at bridge position (Obr) favors the stable surface intermediate mechanism where high energy requirements for forward reactions are demonstrated in our calculations. On RuO2-Oot(110) surface, however, higher reactivity of the electrophilic oxygen (Oot) species lowers the reaction barriers and enables an exothermic reaction path to the direct oxygen insertion for PO production. Therefore, RuO2-Oot surface is expected to show a higher PO rate.

  14. Characterization of Bimetallic Fe-Ru Oxide Nanoparticles Prepared by Liquid-Phase Plasma Method

    Science.gov (United States)

    Lee, Sung-Jin; Lee, Heon; Jeon, Ki-Joon; Park, Hyunwoong; Park, Young-Kwon; Jung, Sang-Chul

    2016-07-01

    The bimetallic Fe-Ru oxide nanoparticles were synthesized in the liquid-phase plasma (LPP) method which employed iron chloride and ruthenium chloride as precursors. The active species (OH·, Hα, Hβ, and OI) and the iron and ruthenium ions were observed in the plasma field created by the LPP process. The spherical-shaped bimetallic Fe-Ru oxide nanoparticles were synthesized by the LPP reaction, and the size of the particles was growing along with the progression of the LPP reaction. The synthesized bimetallic Fe-Ru oxide nanoparticles were comprised of Fe2O3, Fe3O4, RuO, and RuO2. Ruthenium had a higher reduction potential than iron and resulted in higher ruthenium composition in the synthesized bimetallic nanoparticles. The control of the molar ratio of the precursors in the reactant solution was found to be employed as a means to control the composition of the elements in bimetallic nanoparticles.

  15. Enhanced thermoelectric power and electronic correlations in RuSe2

    Directory of Open Access Journals (Sweden)

    Kefeng Wang

    2015-04-01

    Full Text Available We report the electronic structure, electric and thermal transport properties of Ru1−xIrxSe2 (x ≤ 0.2. RuSe2 is a semiconductor that crystallizes in a cubic pyrite unit cell. The Seebeck coefficient of RuSe2 exceeds −200 μV/K around 730 K. Ir substitution results in the suppression of the resistivity and the Seebeck coefficient, suggesting the removal of the peaks in density of states near the Fermi level. Ru0.8Ir0.2Se2 shows a semiconductor-metal crossover at about 30 K. The magnetic field restores the semiconducting behavior. Our results indicate the importance of the electronic correlations in enhanced thermoelectricity of RuSb2.

  16. Effect of Ln3+ on Inhibition of Tobacco RuBPcase

    Institute of Scientific and Technical Information of China (English)

    陈为钧; 陶冶; 胡天斗; 赵贵文

    2002-01-01

    The tobacco RuBPcase was purified by the method of (NH4)2SO4 precipitation and Sephadex G-200 column chromatography. The effects of Ln3+ on inhibition of RuBPcase activity were studied. The results show that the vmax (maximum velocity) of RuBPcase does not change, but its km (Michaelis constant) increases with a ki (inhibitor constant) when increasing the concentration of Ln3+ in enzymatic reaction. It indicates that the inhibitory action of Ln3+ on tobacco RuBPcase is a model of competitive inhibition with Mg2+. The ki of La3+, Ce3+ and Gd3+ is 26.3, 34.3 and 200 μmol*L-1, respectively. Their inhibitory action on the RuBPcase is in the order of La3+>Ce3+Gd3+.

  17. Preparation and characterization oF Ru-Sn/Al2O3 catalysts for the hydrogenation of fatty acid methyl esters

    Directory of Open Access Journals (Sweden)

    Vanina A. Mazzieri

    2010-01-01

    Full Text Available Ru-Sn/Al2O3 catalysts with different Sn loadings were prepared by the coimpregnation method. Several characterization techniques such as TPR, pyridine TPD and catalytic tests for dehydrogenation and hydrogenolysis were used to evaluate and compare such catalysts. TPR results indicate that Sn is deposited both onto the support and as species strongly interacting with Ru. Such non selective deposition modifies the acid and metallic functions of the catalysts. Both total acidity and acid strength distribution are affected: total acidity decreases and new sites of lower acid strength are created. Both dehydrogenating and hydrogenolytic activities are strongly diminished by the addition of Sn. Results of catalytic tests for methyl oleate hydrogenation indicate that methyl stearate is the main product, with only minute amounts of oleyl alcohol produced, and that the addition of Sn diminishes the hydrogenation activity.

  18. Moessbauer effect and magnetization studies of Nd{sub 16}Fe{sub 76-x}Ru {sub x}B{sub 8} alloys

    Energy Technology Data Exchange (ETDEWEB)

    Valcanover, J.A. [DF-UFSC, Florianopolis, CEP 88040-900, SC (Brazil); Paduani, C. [DF-UFSC, Florianopolis, CEP 88040-900, SC (Brazil)]. E-mail: paduani@fisica.ufsc.br; Ardisson, J.D. [CDTN, Belo Horizonte, CEP 30123-970, MG (Brazil); Samudio Perez, C.A. [FEA-UPF, Passo Fundo, CEP 99001-970, RS (Brazil); Yoshida, M.I. [DQ-UFMG, Belo Horizonte, CEP 31270-901, MG (Brazil)

    2005-05-15

    The intrinsic magnetic properties of Nd{sub 16}Fe{sub 76-x}Ru {sub x}B{sub 8} alloys are investigated by means of Moessbauer spectroscopy and magnetization measurements. The Moessbauer parameters derived from fitting the six sextets assigned to the six different iron sites provide information about preferential site occupation of solute atoms. The cell volume decreases with the Ru substitution for Fe and the shrinkage of the lattice is greater in the c direction than in the a direction of the tetragonal unit cell. The decrease of the spectral area for the subpatterns corresponding to k{sub 1} and k{sub 2} sites with the substitution indicates that the ruthenium atoms enter preferentially in these sites, whereas the Fe atoms prefer the j-sites. The behavior of the Moessbauer parameters with changes in composition indicates that the ruthenium interactions have long range order character in this compound.

  19. Magneto-elastic coupling across the first-order transition in the distorted kagome lattice antiferromagnet Dy3Ru4Al12

    Science.gov (United States)

    Henriques, M. S.; Gorbunov, D. I.; Kriegner, D.; Vališka, M.; Andreev, A. V.; Matěj, Z.

    2016-02-01

    Structural changes through the first-order paramagnetic-antiferromagnetic phase transition of Dy3Ru4Al12 at 7 K have been studied by means of X-ray diffraction and thermal expansion measurements. The compound crystallizes in a hexagonal crystal structure of Gd3Ru4Al12 type (P63/mmc space group), and no structural phase transition has been found in the temperature interval between 2.5 and 300 K. Nevertheless, due to the spin-lattice coupling the crystal volume undergoes a small orthorhombic distortion of the order of 2×10-5 as the compound enters the antiferromagnetic state. We propose that the first-order phase transition is not driven by the structural changes but rather by the exchange interactions present in the system.

  20. Energy deposition by a {sup 106}Ru/{sup 106}Rh eye applicator simulated using LEPTS, a low-energy particle track simulation

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, M.C. [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Munoz, A.; Oller, J.C. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avenida Complutense 22, 28040 Madrid (Spain); Blanco, F. [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid, Avenida Complutense, 28040 Madrid (Spain); Williart, A. [Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey 9, 28040 Madrid (Spain); Limao-Vieira, P. [Laboratorio de Colisoes Atomicas e Moleculares, Departamento de Fisica, CEFITEC, FCT-Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica (Portugal); Borge, M.J.G.; Tengblad, O. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Huerga, C.; Tellez, M. [Hospital Universitario La Paz, Paseo de la Castellana 261, 28046 Madrid (Spain); Garcia, G., E-mail: g.garcia@iff.csic.es [Instituto de Fisica Fundamental, Consejo Superior de Investigaciones Cientificas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Departamento de Fisica de los Materiales, Universidad Nacional de Educacion a Distancia, Senda del Rey 9, 28040 Madrid (Spain)

    2011-09-15

    The present study introduces LEPTS, an event-by-event Monte Carlo programme, for simulating an ophthalmic {sup 106}Ru/{sup 106}Rh applicator relevant in brachytherapy of ocular tumours. The distinctive characteristics of this code are the underlying radiation-matter interaction models that distinguish elastic and several kinds of inelastic collisions, as well as the use of mostly experimental input data. Special emphasis is placed on the treatment of low-energy electrons for generally being responsible for the deposition of a large portion of the total energy imparted to matter. - Highlights: > We present the Monte Carlo code LEPTS, a low-energy particle track simulation. > Carefully selected input data from 10 keV to 1 eV. > Application to an electron emitting Ru-106/Rh-106 plaque used in brachytherapy.

  1. Preparation and characterization of Ru-Sn/Al{sub 2}O{sub 3} catalysts for the hydrogenation of fatty acid methyl esters

    Energy Technology Data Exchange (ETDEWEB)

    Mazzieri, Vanina A.; Sad, Mario R.; Vera, Carlos R.; Pieck, Carlos L. [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Investigaciones en Catalisis y Petroquimica; Grau, Ricardo [Consejo Nacional de Investigaciones Cientificas y Tecnicas, Santa Fe (Argentina). Universidad Nacional del Litoral. Inst. de Desarrollo Tecnologico para la Industria Quimica

    2010-07-01

    Ru-Sn/Al{sub 2}O{sub 3} catalysts with different Sn loadings were prepared by the coimpregnation method. Several characterization techniques such as TPR, pyridine TPD and catalytic tests for dehydrogenation and hydrogenolysis were used to evaluate and compare such catalysts. TPR results indicate that Sn is deposited both onto the support and as species strongly interacting with Ru. Such non selective deposition modifies the acid and metallic functions of the catalysts. Both total acidity and acid strength distribution are affected: total acidity decreases and new sites of lower acid strength are created. Both dehydrogenating and hydrogenolytic activities are strongly diminished by the addition of Sn. Results of catalytic tests for methyl oleate hydrogenation indicate that methyl stearate is the main product, with only minute amounts of oleyl alcohol produced, and that the addition of Sn diminishes the hydrogenation activity. (author)

  2. Ru-N-C Hybrid Nanocomposite for Ammonia Dehydrogenation: Influence of N-doping on Catalytic Activity

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Bich Hien

    2015-06-01

    Full Text Available For application to ammonia dehydrogenation, novel Ru-based heterogeneous catalysts, Ru-N-C and Ru-C, were synthesized via simple pyrolysis of a mixture of RuCl3·6H2O and carbon black with or without dicyandiamide as a nitrogen-containing precursor at 550 °C. Characterization of the prepared Ru-N-C and Ru-C catalysts via scanning transmission electron microscopy, in conjunction with energy dispersive X-ray spectroscopy, indicated the formation of hollow nanocomposites in which the average sizes of the Ru nanoparticles were 1.3 nm and 5.1 nm, respectively. Compared to Ru-C, the Ru-N-C nanocomposites not only proved to be highly active for ammonia dehydrogenation, giving rise to a NH3 conversion of >99% at 550 °C, but also exhibited high durability. X-ray photoelectron spectroscopy revealed that the Ru active sites in Ru-N-C were electronically perturbed by the incorporated nitrogen atoms, which increased the Ru electron density and ultimately enhanced the catalyst activity.

  3. The mouse ruby-eye 2(d) (ru2(d) /Hps5(ru2-d) ) allele inhibits eumelanin but not pheomelanin synthesis.

    Science.gov (United States)

    Hirobe, Tomohisa; Ito, Shosuke; Wakamatsu, Kazumasa

    2013-09-01

    The novel mutation named ru2(d) /Hps5(ru2-d) , characterized by light-colored coats and ruby-eyes, prohibits differentiation of melanocytes by inhibiting tyrosinase (Tyr) activity, expression of Tyr, Tyr-related protein 1 (Tyrp1), Tyrp2, and Kit. However, it is not known whether the ru2(d) allele affects pheomelanin synthesis in recessive yellow (e/Mc1r(e) ) or in pheomelanic stage in agouti (A) mice. In this study, effects of the ru2(d) allele on pheomelanin synthesis were investigated by chemical analysis of melanin present in dorsal hairs of 5-week-old mice from F2 generation between C57BL/10JHir (B10)-co-isogenic ruby-eye 2(d) and B10-congenic recessive yellow or agouti. Eumelanin content was decreased in ruby-eye 2(d) and ruby-eye 2(d) agouti mice, whereas pheomelanin content in ruby-eye 2(d) recessive yellow and ruby-eye 2(d) agouti mice did not differ from the corresponding Ru2(d) /- mice, suggesting that the ru2(d) allele inhibits eumelanin but not pheomelanin synthesis. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Fused donor-acceptor ligands in RuII chemistry: synthesis, electrochemistry and spectroscopy of [Ru(bpy)3-n(TTF-dppz)n](PF6)2.

    Science.gov (United States)

    Goze, Christine; Leiggener, Claudia; Liu, Shi-Xia; Sanguinet, Lionel; Levillain, Eric; Hauser, Andreas; Decurtins, Silvio

    2007-07-16

    Three ruthenium(II) polypyridine complexes of general formula [Ru(bpy)(3-n)(TTF-dppz)n](PF6)2 (n=1-3, bpy=2,2'-bipyridine), with one, two or three redox-active TTF-dppz (4',5'-bis(propylthio)tetrathiafulvenyl[i]dipyrido[3,2-a:2',3'-c]phenazine) ligands, were synthesised and fully characterised. Their electrochemical and photophysical properties are reported together with those of the reference compounds [Ru(bpy)3](PF6)2, [Ru(dppz)3](PF6)2 and [Ru(bpy)2(dppz)](PF6)2 and the free TTF-dppz ligand. All three complexes show intraligand charge-transfer (ILCT) fluorescence of the TTF-dppz ligand. Remarkably, the complex with n=1 exhibits luminescence from the Ru(2+)-->dppz metal-to-ligand charge-transfer ((3)MLCT) state, whereas for the other two complexes, a radiationless pathway via electron transfer from a second TTF-dppz ligand quenches the (3)MLCT luminescence. The TTF fragments as electron donors thus induce a ligand-to-ligand charge-separated (LLCS) state of the form TTF-dppz- -Ru(2+)-dppz-TTF(+). The lifetime of this LLCS state is approximately 2.3 micros, which is four orders of magnitude longer than that of 0.4 ns for the ILCT state, because recombination of charges on two different ligands is substantially slower.

  5. Synthesis, characterization, and DNA-binding studies of ruthenium complexes [Ru(tpy)(ptn)]2+ and Ru(dmtpy)(ptn)]2+.

    Science.gov (United States)

    Li, Lü-Ying; Jia, Hai-Na; Yu, Hui-Juan; Du, Ke-Jie; Lin, Qi-Tian; Qiu, Kang-Qiang; Chao, Hui; Ji, Liang-Nian

    2012-08-01

    Two ruthenium(II) polypyridyl complexes [Ru(tpy)(ptn)](2+) (1) and Ru(dmtpy)(ptn)](2+) (2) (ptn=3-(1,10-phenanthrolin-2-yl)-as-triazino[5,6-f]naphthalene, tpy=2,2':6',2"-terpyridine, dmtpy=5,5'-dimethyl-2,2':6',2"-terpyridine) have been synthesized and characterized by elemental analysis, (1)H NMR, mass spectrometry and crystal structure analysis. Spectroscopic studies together with isothermal titration calorimetry (ITC) and viscosity measurements prove that two complexes bind to DNA in an intercalative mode. ITC experiments show that the binding mode for complex 2 is entropically driven, while an entropy-driven initial binding of complex 1 is followed by an entropically and enthalpically favorable process. This difference may be attributed to the ancillary ligand effects on the DNA binding of Ru(II) complexes. Circular dichroism titrations of calf thymus DNA (CT-DNA) with Ru(II) complexes show that complexes 1 and 2 induce B to Z conformational transition of calf thymus DNA at low ionic strength (0.05 M NaCl). The induced Z-DNA conformation can revert to B form when Ru(II) complexes are displaced by ethidium bromide or at high ionic strengths ([NaCl]=0.4 M), but keeps intact with temperature ranged from 25 to 90 °C. The unique structure and characteristics of Ru(II) complexes designed in this investigation will be useful for the study of Z-DNA.

  6. Moessbauer effect studies of disordered Fe-Ru alloys

    Energy Technology Data Exchange (ETDEWEB)

    Poettker, W.E.; Paduani, C. [Departamento de Fisica, Universidade Federal de Santa Catarina, UFSC, Florianopolis, CEP 88040-900, SC (Brazil); Ardisson, J.D. [Centro de Desenvolvimento da Tecnologia Nuclear, CDTN, Belo Horizonte, CEP 30123-970, MG (Brazil); Ioshida, M.I. [Departamento de Quimica, Universidade Federal de Minas Gerais, ICEX-UFMG, Belo Horizonte, Caixa Postal 702, CEP 31270-901, MG (Brazil)

    2004-09-01

    The bcc and hcp phases of disordered Fe{sub 100-x}Ru{sub x} alloys are investigated with several experimental techniques to study the composition dependence of the magnetic properties in these structures. With an appropriate annealing the prepared samples are single phase. The iron rich alloys are ferromagnetic at room temperature with the bcc structure. However, an antiferromagnetic coupling is introduced with the addition of ruthenium. Above 30 at% Ru a paramagnetic behavior is observed at 300 K and 77 K, where the alloys have the hcp structure. In the ferromagnetic phase the Curie temperature decreases steadily with the increase of the ruthenium concentration. In the paramagnetic hcp phase the mean volume per atom is al-most triplicated as compared to the bcc phase, which brings out the breakdown of the magnetization and the collapse of the hyperfine field at the iron sites simultaneously with the crystallographic phase transition. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Distance dependence of intrahelix Ru(II)* to Os(II) polypyridyl excited-state energy transfer in oligoproline assemblies.

    Science.gov (United States)

    Brennaman, M Kyle; Fleming, Cavan N; Slate, Cheryl A; Serron, Scafford A; Bettis, Stephanie E; Erickson, Bruce W; Papanikolas, John M; Meyer, Thomas J

    2013-05-30

    Energy transfer between the metal-to-ligand charge transfer (MLCT) excited states of [Pra [M(II)(bpy)2(4-Me-4'(-N(H)CO)bpy)](PF6)2 units ([Pra(M(II)bpy2(mbpy)](2+): M(II) = Ru(II) or Os(II), bpy = 2,2'-bipyridine, mbpy = 4'-methyl-2,2'-bipyridine-4-carboxamido, Pra = 4-M(II)-L-proline) linked covalently to oligoproline assemblies in room temperature acetonitrile occurs on the picosecond-nanosecond time scale and has been time-resolved by transient emission measurements. Three derivatized oligoprolines, [CH3-CO-Pro6-Pra[Os(II)(bpy)2(mbpy)](2+)-Pro2-Pra[Ru(II)(bpy)2(mbpy)](2+)-Pro2-Pra[Ru(II)(bpy)2(mbpy)](2+)-Pro6-Glu-NH2](6+) (ORR-2, Pro = L-proline and Glu = glutamic acid); [CH3-CO-Pro6-Pra[Os(II)(bpy)2(mbpy)](2+)-Pro3-Pra[Ru(II)(bpy)2(mbpy)](2+)-Pro3-Pra[Ru(II)(bpy)2(mbpy)](2+)-Pro6-Glu-NH2](6+) (ORR-3); and CH3-CO-Pro6-Pra[Os(II)(bpy)2(mbpy)](2+)-Pro5-Pra[Ru(II)(bpy)2(mbpy)](2+)-Pro5-Pra[Ru(II)(bpy)2(mbpy)](2+)Pro6-Glu2-NH2](6+) (ORR-5), were prepared by using solid-phase peptide synthesis. Given the helical nature of the resulting assemblies and the nature of the synthesis, composition, length, and loading pattern are precisely controlled in the assemblies. In acetonitrile, they adopt a proline I helical secondary structure, confirmed by circular dichroism, in which the appended chromophores are ordered in well-defined orientations and internuclear separation distances although helix formation for ORR-2 is incomplete. Quantitative comparison of oligoproline ground-state absorption and steady-state emission spectra to those for the constituents, [Boc-Pra[M(II)(bpy)2(mbpy)](2+)-OH](PF6)2 (Boc = N(α)-(1,1-dimethylethoxycarbonyl), shows that following Ru(II) light absorption, Ru(II)* undergoes facile energy transfer resulting in sensitization of Os(II). Sensitization efficiencies are 93% for ORR-2, 77% for ORR-3, and 73% for ORR-5. Picosecond-resolved emission measurements reveal complex, coupled dynamics that arise from excited-state decay and kinetically

  8. Methanol oxidation at carbon paste electrodes modified with (Pt–Ru)/carbon aerogels nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Fort, Carmen I., E-mail: iladiu@chem.ubbcluj.ro [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Cotet, Liviu C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania); Vasiliu, Florin [The National Institute of Materials Physics, Atomistilor str. 105 bis, PO Box MG. 7, Magurele, RO 077125, Bucharest (Romania); Marginean, Petre [National Institute for Research and Development of Isotopic and Molecular Technologies, RO 400293, Cluj-Napoca (Romania); Danciu, Virginia; Popescu, Ionel C. [Laboratory of Electrochemical Research and Nonconventional Materials, Babes-Bolyai University, Arany Janos 11, RO-400028, Cluj-Napoca (Romania)

    2016-04-01

    Mesoporous carbon aerogels (CAs) impregnated with (Pt–Ru) nanoparticles were prepared, incorporated into carbon paste electrodes (CPEs) and investigated as electrocatalysts for CH{sub 3}OH electro-oxidation. The sol–gel method, followed by supercritical drying with liquid CO{sub 2} and thermal pyrolysis in an inert atmosphere, was used to obtain high mesoporous CAs. (Pt–Ru)/CAs nanocomposites with various (Pt–Ru) loading were prepared by using Ru(AcAc){sub 3} and H{sub 2}PtCl{sub 6} as metal precursors and the impregnation method. The morpho-structural peculiarities of the so prepared (Pt–Ru)/CAs electrocatalysts were examined by using elemental analysis, N{sub 2} adsorption-desorption isotherms, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (EDX) and selected area electron diffraction (SAED). Cyclic voltammetry measurements, carried out at (Pt–Ru)/CA-CPEs incorporating nanocomposites with various Pt–Ru loading and different specific surface areas, showed that CA with the highest specific surface area (843 m{sup 2}/g) and impregnated with 6% (w/w) (Pt–Ru) nanoparticles exhibit the best CH{sub 3}OH electro-oxidation efficiency. The Michaelis–Menten formalism was used to describe the dependence of the oxidation peak current on the CH{sub 3}OH concentration, allowing the estimation of the modified electrodes sensitivities. Thus, for (Pt–Ru, 10%)/CA{sub 535}-CPE was observed the highest sensitivity (12.5 ± 0.8 mA/M) and, at the same time, the highest maximum current density ever reported (153.1 mA/cm{sup 2} for 2 M CH{sub 3}OH and an applied potential of 600 mV vs. SHE). - Highlights: • (Pt–Ru) nanoparticles were deposited on high mesoporous carbon aerogels (CAs). • (Pt–Ru)/CAs were characterized by TEM, EDX, SAED and N{sub 2} adsorption-desorption. • Carbon paste electrodes modified with (Pt–Ru)/CA were used for CH{sub 3}OH oxidation. • (Pt–Ru, 10

  9. Synthesis and Isomeric Analysis of Ru(II) Complexes Bearing Pentadentate Scaffolds.

    Science.gov (United States)

    Gil-Sepulcre, Marcos; Axelson, Jordan C; Aguiló, Joan; Solà-Hernández, Lluís; Francàs, Laia; Poater, Albert; Blancafort, Lluís; Benet-Buchholz, Jordi; Guirado, Gonzalo; Escriche, Lluís; Llobet, Antoni; Bofill, Roger; Sala, Xavier

    2016-11-07

    A Ru(II)-pentadentate polypyridyl complex [Ru(II)(κ-N(5)-bpy2PYMe)Cl](+) (1(+), bpy2PYMe = 1-(2-pyridyl)-1,1-bis(6-2,2'-bipyridyl)ethane) and its aqua derivative [Ru(II)(κ-N(5)-bpy2PYMe)(H2O)](2+) (2(2+)) were synthesized and characterized by experimental and computational methods. In MeOH, 1(+) exists as two isomers in different proportions, cis (70%) and trans (30%), which are interconverted under thermal and photochemical conditions by a sequence of processes: chlorido decoordination, decoordination/recoordination of a pyridyl group, and chlorido recoordination. Under oxidative conditions in dichloromethane, trans-1(2+) generates a [Ru(III)(κ-N(4)-bpy2PYMe)Cl2](+) intermediate after the exchange of a pyridyl ligand by a Cl(-) counterion, which explains the trans/cis isomerization observed when the system is taken back to Ru(II). On the contrary, cis-1(2+) is in direct equilibrium with trans-1(2+), with absence of the κ-N(4)-bis-chlorido Ru(III)-intermediate. All these equilibria were modeled by density functional theory calculations. Interestingly, the aqua derivative is obtained as a pure trans-[Ru(II)(κ-N(5)-bpy2PYMe)(H2O)](2+) isomer (trans-2(2+)), while the addition of a methyl substituent to a single bpy of the pentadentate ligand leads to the formation of a single cis isomer for both chlorido and aqua derivatives [Ru(II)(κ-N(5)-bpy(bpyMe)PYMe)Cl](+) (3(+)) and [Ru(II)(κ-N(5)-bpy(bpyMe)PYMe)(H2O)](2+) (4(2+)) due to the steric constraints imposed by the modified ligand. This system was also structurally and electrochemically compared to the previously reported [Ru(II)(PY5Me2)X](n+) system (X = Cl, n = 1 (5(+)); X = H2O, n = 2 (6(2+))), which also contains a κ-N(5)-Ru(II) coordination environment, and to the newly synthesized [Ru(II)(PY4Im)X](n+) complexes (X = Cl, n = 1 (7(+)); X = H2O, n = 2 (8(2+))), which possess an electron-rich κ-N(4)C-Ru(II) site due to the replacement of a pyridyl group by an imidazolic carbene.

  10. An Insight into the Anticancer Activities of Ru(II-Based Metallocompounds Using Docking Methods

    Directory of Open Access Journals (Sweden)

    Peter A. Ajibade

    2013-09-01

    Full Text Available Unlike organic molecules, reports on docking of metal complexes are very few; mainly due to the inadequacy of force fields in docking packages to appropriately characterize the metal atoms that consequentially hinder the rational design of metal-based drug complexes. In this study we have made used Molegro and Autodock to predict the anticancer activities of selected Ru(II complexes against twelve anticancer targets. We observed that introducing the quantum calculated atomic charges of the optimized geometries significantly improved the docking predictions of these anticancer metallocompounds. Despite several limitations in the docking of metal-based complexes, we obtained results that are highly correlated with the available experimental results. Most of our newly proposed metallocompounds are found theoretically to be better anticancer metallocompounds than all the experimentally proposed RAPTA complexes. An interesting features of a strong interactions of new modeled of metallocompounds against the two base edges of DNA strands suggest similar mechanisms of anticancer activities similar to that of cisplatin. There is possibility of covalent bonding between the metal center of the metallocompounds and the residues of the receptors DNA-1, DNA-2, HDAC7, HIS and RNR. However, the general results suggest the possibility of metals positioning the coordinated ligands in the right position for optimal receptor interactions and synergistic effects, rather than forming covalent bonds.

  11. Anelastic characterization and superconducting properties of RuSr2GdCu2O8+δ

    Directory of Open Access Journals (Sweden)

    Jurelo, A. R.

    2008-08-01

    Full Text Available Since the discovery of the high Tc superconductors, many researches have been carried out on the different properties of these materials, especially on the transition temperature into the superconducting state. The rutheno-cuprates belong to a new class of composites, which were synthesized for the first time by Bauernfeind in 1995. Bernhard and collaborators discovered, in 1999, the coexistence of the ferromagnetism and the superconductivity in this phase, which is known as antagonistic phenomenon in the electromagnetism due to spin-charge interactions established in these states. However, the physical nature of the superconducting and magnetic states is still very obscure. The non-stoichiometric (interstitial oxygen is considered as a possible cause for the non-uniformity of the sample properties. In this paper, results of mechanical spectroscopy in Ru-1212 samples are presented showing complex anelastic spectra, which were attributed to the mobility of the interstitial oxygen atoms in the Ru-1212 lattice.Desde el descubrimiento de los superconductores de alta Tc, muchas investigaciones han sido realizadas sobre las diferentes propiedades de estos materiales, especialmente sobre la temperatura de transición dentro del estado superconductor. Los cupratos de rutenio pertenecen a una nueva clase de compositos, los cuales fueron sintetizados por primera vez por Bauernfeind en 1995. Bernhard y colaboradores descubrieron, en 1999, la coexistencia del ferromagnetismo y la superconductividad en esta fase, lo cual es conocido como un fenómeno antagonistico en el electromagnetismo debido a las interacciones spin-carga establecidas en estos estados. Sin embargo, la naturaleza física de los estados superconductores y magnéticos aun no son muy claros. El oxigeno no-estequiométrico (intersticial es considerado como una causa de la no-uniformidad de las propiedades de la muestra. En este articulo, los resultados de espectroscopia mecánica en muestras

  12. Photoluminescence quenching/recovery kinetics of [Ru(bpy)2(tatp)]2+ and [Ru(bpy)2(dmtatp)]2+ intercalated within DNA by copper(II) ions and EDTA.

    Science.gov (United States)

    Ji, Shibo; Chen, Miaojing; Gan, Guilian; Li, Hong; Li, Weishan

    2012-03-01

    The quenching and recovery kinetics of photoluminescence of [Ru(bpy)(2)(tatp)](2+) (Ru1) and [Ru(bpy)(2)(dmtatp)](2+) (Ru2) intercalated within DNA (where bpy=2,2'-bipyridine, tatp=1,4,8,9-tetra-aza-triphenylene and dmtatp=2,3-dimethyl-1,4,8,9-tetra-aza-triphenylene) have been investigated by steady-state and time-resolved methods performed at various temperatures (293-333K). Two complexes Ru1 and Ru2 show a single-exponential luminescence decay with τ(Ru1)=246.0 ns and τ(Ru2)=513.5 ns, whose luminescence upon intercalating into DNA exhibits very consistent bi-exponential decay changes. The addition of Cu(2+) ions is found to dynamically quench the luminescence of both DNA-bound Ru(II) complexes, involving a spontaneous exothermic process. The sequential addition of EDTA can partially recover the luminescence quenched by Cu(2+), however depending on methyl substituents of the intercalative ligand. The chemical conversion and luminescence control mechanism of the two DNA-bound Ru(II) complexes is discussed in detail. The present results should be of value for better understanding chemical modulation of DNA-bound Ru(II) complexes as luminescence probes. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. The electrical and magnetic properties of ferromagnetic-superconducting compound Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ

    Directory of Open Access Journals (Sweden)

    A Khajehnezhad

    2009-08-01

    Full Text Available   Coexistence of superconductivity and magnetic ordering or their mutually exclusive existence in solids is one of the fundamental problems of solid state physics. To determine the effect of Pr substitution for Gd on electrical and magnetic properties of RuGd1.5Ce0.5Sr2Cu2O10-δ (Ru-1222, Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ with x=0.0, 0.01, 0.03, 0.03 3 , 0.04, 0.05, 0.06, 0.1 have been prepared by the standard solid-state reaction technique. The XRD patterns for various x have been obtained to show their phase purity. The resistivity and magnetoresistivity of samples have been measured at various temperatures and different magnetic fields up to 1.5T . Superconductivity and magnetic parameters such as superconducting transition temperature Tc and magnetic transition Tirr, have been obtained through resistivity curves. The sharp decrease in Tc with x in Ru(Gd1.5-xPrxCe0.5Sr2Cu2O10-δ shows competition between pair breaking by magnetic impurity, hole doping because of different valance of ions, difference in ionic radii and oxygen stoichiometry, which affect on superconducting transition. In Pr substitution for Gd, the small difference between Gd3+ and Pr3+,4+ ionic radii decreases the mean Ru-Ru distance, and as a result, the magnetic exchange interaction can become stronger with increasing x. Both Tc and Tirr decrease with external magnetic field .

  14. Preparation of a DNA-bound [Ru(bpy)2(mbpibH2)]2+ film and its two-mode luminescence tuning by copper(II) ions and EDTA

    Science.gov (United States)

    Gan, Gui-Lian; Chao, Hui; Ji, Shi-Bo; Chen, Lin-Lin; Li, Hong

    2012-11-01

    An imidazophenanthroline-containing ruthenium(II) complex [Ru(bpy)2(mbpibH2)]2+ (bpy = 2,2'-bipyridine, mbpibH2 = 1,3-bis([1,10]phenanthroline[5,6-d]imidazol-2-yl)benzene) can bind DNA through groove-binding and/or non-classical intercalation modes, revealed by spectrophotometric methods, viscosity measurements and variable ionic strength experiments. On the basis of binding interactions between cationic [Ru(bpy)2(mbpibH2)]2+ and anionic DNA at a molar ratio of 1:1, a yellow transparent cast film has been assembled on an indium-tin oxide (ITO) surface using a solution-based self-standing method. The prepared DNA-[Ru(bpy)2(mbpibH2)]2+ film shows a bi-exponential luminescence decay with τ1 = 62.1 ns (8.0%) and τ2 = 594.5 ns (92.0%), whose lifetimes become much shorter than those of DNA-bound [Ru(bpy)2(mbpibH2)]2+ in buffer solutions. The Ru(II) complex with a free bi-dentate coordination site in the DNA cast film shows tunable luminescence, quenched dynamically by Cu2+ and restored by using EDTA to eliminate two modes of Cu2+-binding. The results from this study provide a significant foundation for better understanding the fabrication and modulation of a DNA-based solid luminescence device using the Ru(II) complexes as DNA-concentrating and signal-sensing agents.

  15. Formation of a series of chimney-ladder compounds in the Ru-Re-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Simkin, B.A. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Ishida, A. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Okamoto, N.L. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Kishida, K. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)]. E-mail: k.kishida@materials.mbox.media.kyoto-u.ac.jp; Tanaka, K. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan); Inui, H. [Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)

    2006-06-15

    Rhenium-alloyed ruthenium sesquisilicide alloys have been prepared over the wide composition range Ru{sub 1-{delta}}Re {sub {delta}}Si{sub 1.5}, 0 {<=} {delta} {<=} 0.85. The phase relationships of these alloys have been investigated using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Alloys with {delta} {>=} 0.03 are multi-phase, composed of a series of (Ru,Re)Si {sub y} chimney-ladder phases with compositions of Ru{sub 1-x}Re {sub x}Si{sub 1.5386+0.1783x} (0.14 {<=} x {<=} 0.76) and B20-type monosilicide (Ru,Re)Si as a secondary phase. These chimney-ladder structures are considered to form to stabilize the high-temperature Ru{sub 2}Si{sub 3} chimney-ladder phase through the substitution of Ru with Re. The solubility limit of Re in a series of chimney-ladder phases is as large as 76% Re (x = 0.76) and the Si/(Ru + Re) ratio of the chimney-ladder phases increases with increasing Re content. The observed deviation of the chimney-ladder structure from the idealized composition and the possibility of adjusting the semiconducting properties of these chimney-ladder structures are discussed in terms of the valence electron concentration per metal atom.

  16. Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6.

    Science.gov (United States)

    Okamoto, Satoshi; Ochi, Masayuki; Arita, Ryotaro; Yan, Jiaqiang; Trivedi, Nandini

    2017-09-13

    Electron correlations tend to generate local magnetic moments that usually order if the lattices are not too frustrated. The hexagonal compound SrRu2O6 has a relatively high Neel temperature but small local moments, which seem to be at odds with the nominal valence of Ru(5+) in the [Formula: see text] configuration. Here, we investigate the electronic property of SrRu2O6 using density functional theory (DFT) combined with dynamical-mean-field theory (DMFT). We find that the strong hybridization between Ru d and O p states results in a Ru valence that is closer to +4, leading to the small ordered moment ~1.2 μ B . While this is consistent with a DFT prediction, correlation effects are found to play a significant role. The local moment per Ru site remains finite ~2.3 μ B in the whole temperature range investigated. Due to the lower symmetry, the t 2g manifold is split and the quasiparticle weight is renormalized significantly in the a 1g state, while the renormalization in [Formula: see text] states is about a factor of 2-3 weaker. Our theoretical Neel temperature ~700 K is in reasonable agreement with experimental observations. SrRu2O6 is a unique system in which localized and itinerant electrons coexist with the proximity to an orbitally-selective Mott transition within the t 2g sector.

  17. Is the semi-regular variable RU Vulpeculae undergoing a helium-shell flash?

    CERN Document Server

    Uttenthaler, S; Templeton, M

    2015-01-01

    The semi-regular variable star RU Vulpeculae (RU Vul) is being observed visually since 1935. Its pulsation period and amplitude are declining since $\\sim1954$. A leading hypothesis to explain the period decrease in asymptotic giant branch (AGB) stars such as RU Vul is an ongoing flash of the He-burning shell, also called a thermal pulse (TP), inside the star. In this paper, we present a CCD photometric light curve of RU Vul, derive its fundamental parameters, and test if the TP hypothesis can describe the observed period decline. We use CCD photometry to determine the present-day pulsation period and amplitude in three photometric bands, and high-resolution optical spectroscopy to derive the fundamental parameters. The period evolution of RU Vul is compared to predictions by evolutionary models of the AGB phase. We find that RU Vul is a metal-poor star with a metallicity $[{\\rm M}/{\\rm H}]=-1.59\\pm0.05$ and an effective surface temperature of $T_{\\rm eff}=3634\\pm20$ K. The low metallicity of RU Vul and its ki...

  18. Stable monolayer honeycomb-like structures of RuX2 (X =S,Se)

    Science.gov (United States)

    Ersan, Fatih; Cahangirov, Seymur; Gökoǧlu, Gökhan; Rubio, Angel; Aktürk, Ethem

    2016-10-01

    Recent studies show that several metal oxides and dichalcogenides (M X2) , which exist in nature, can be stable in two-dimensional (2D) form and each year several new M X2 structures are explored. The unstable structures in H (hexagonal) or T (octahedral) forms can be stabilized through Peierls distortion. In this paper, we propose new 2D forms of RuS2 and RuSe2 materials. We investigate in detail the stability, electronic, magnetic, optical, and thermodynamic properties of 2D Ru X2 (X =S,Se) structures from first principles. While their H and T structures are unstable, the distorted T structures (T'-Ru X2) are stable and have a nonmagnetic semiconducting ground state. The molecular dynamic simulations also confirm that T'-Ru X2 systems are stable even at 500 K without any structural deformation. T'-RuS2 and T'-RuSe2 have indirect band gaps with 0.745 eV (1.694 eV with HSE) and 0.798 eV (1.675 eV with HSE) gap values, respectively. We also examine their bilayer and trilayer forms and find direct and smaller band gaps. We find that AA stacking is more favorable than the AB configuration. The new 2D materials obtained can be good candidates with striking properties for applications in semiconductor electronic, optoelectronic devices, and sensor technology.

  19. Transformation,Deformation and Microstructure Characteristics of Ru50Ta50 High Temperature Shape Memory Alloy

    Institute of Scientific and Technical Information of China (English)

    Zhirong HE; Fang WANG; Jing'en ZHOU

    2006-01-01

    The basic martensitic transformation(MT)properties of Ru50Ta50 alloy, i.e. MT temperature(MTT), temperature hysteresis(△T), and MT heat(△H)were investigated in this paper. The effects of heat treatment and thermal cycling on MT behavior of Ru50Ta50 alloy, the deformation and microstructure characteristics of Ru50Ta50 alloy were also studied for its engineering application as high temperature actuator/sensor materials by means of differential scanning calorimetry, X-ray diffraction, transmission electron microscope, optical microscope, and hardness test. The results showed that a two-stage reversible MT takes place in Ru50Ta50 alloy.The two-stage MT starting temperatures(M1s, M2s)and the temperature hysteresis(△T1, △T2)are 1047,784 and 11, 14℃, respectively. No significant effect of aging treatment and thermal cycling on MTT and △T of Ru50Ta50 alloy were observed, but △H decreases slowly with increasing thermal cycles. The hardness and brittleness of Ru50Ta50 alloy are high. The deformation mode of RuTa alloys is twinning.

  20. Comment on magnetism and superconductivity in rutheno cuprates: RuSr2GdCu2O8 and RuSr2Gd1.5Ce0.5Cu2O10

    Indian Academy of Sciences (India)

    V P S Awana; M Karppinen; H Yamauchi

    2002-05-01

    Both RuSr2GdCu2O8- (Ru-1212) and RuSr2Gd1.5Ce0.5Cu2O10- (Ru-1222) exhibits magnetism and superconductivity, as seen by magnetization vs. temperature behavior measured in 5 Oe field. Zero-field-cooled (ZFC) and field-cooled (FC) magnetization data show branching at around 140 K and 100 K with a cusp at 135 K and 80 K and a diamagnetic transition around 20 K and 30 K in the ZFC part, for Ru-1212 and Ru-1222, respectively. The isothermal magnetization possesses a non-linear contribution due to a ferromagnetic component at low temperatures below 50 K for both samples. The resistance vs. temperature behavior of the samples in applied fields of 0, 3 and 7 T confirmed superconductivity, with a different type of broadening of the superconductivity transition under magnetic fields for Ru-1212 from that known for conventional high-c superconductors. The magnetoresistance (MR) is negative above the Ru magnetic ordering temperature at 135 K. Below the Ru magnetic ordering temperature, MR displays a positive peak at low fields and becomes negative at higher fields for Ru-1212. For Ru-1222, MR remains negative both above and below the ordering temperature. A maximum of 2% is observed for the negative MR value at the Ru magnetic ordering temperature. An electron diffraction pattern obtained for the Ru-1212 sample shows two types of superstructure: one has a weak spot at the centre of the - rectangle, and the other only along the direction. Interestingly, Ru-1222 shows only clean - and - planes, without any superstructures.

  1. 基于 RU-SMOTE-SVM 的金融市场极端风险预警研究%Research on Extreme Risk Warning for Financial Market Based on RU-SMOTE-SVM

    Institute of Scientific and Technical Information of China (English)

    林宇; 黄迅; 徐凯

    2013-01-01

      本文以上证综指和深证成指为研究对象,将随机欠采样(RU)、合成少数类过采样(SMOTE)与传统支持向量机(SVM)相结合,提出了一种改进的 SVM 模型---RU-SMOTE-SVM 模型来预测我国金融市场极端风险,并与传统 SVM、SMOTE-SVM、RU-SMOTE-NN 和 RU-SMOTE-DT 进行比较。实证结果表明,RU-SMOTE-SVM 既优于传统 SVM 模型,又比 SMOTE-SVM 具有更高的预测精度,同时还展示出比 RU-SMOTE-NN 和 RU-SMOTE-DT 更为优越的预测性能。%Taking the Shanghai Stock Exchange Composite Index and Shenzhen Stock Exchange Component Index as the objects of research, this paper combines Random Under-Sampling(RU), Synthetic Minority Over-Sampling Technique (SMOTE) with Support Vector Machine ( SVM) to establish an improvement SVM---RU-SMOTE-SVM, which is applied to predict the extreme risk in Chinese financial market and compared with conventional SVM, SMOTE-SVM, RU-SMOTE-NN and RU-SMOTE-DT. The result of investigation illustrates that RU-SMOTE-SVM not only outperforms conventional SVM, but also has a higher predictive accuracy than SMOTE-SVM, simultaneously, has a more excellent predictive performance than RU-SMOTE-NN and RU-SMOTE-DT.

  2. Magnetic and magnetocaloric properties of Ba and Ti co-doped SrRuO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal; De, S. K., E-mail: msskd@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2014-12-28

    Temperature evolution of magnetic properties in Ba and Ti doped SrRuO{sub 3} has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161 K to 149 K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak which shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d{sup 0} orbitals for Ru with more delocalized 4d{sup 4} orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160 K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO{sub 3} makes the system more interesting.

  3. Weak-coupling analysis of quasiparticle excitations in Sr2RuO4 along the Γ -M cut

    Science.gov (United States)

    Deisz, J. J.; Kidd, T. E.

    2017-01-01

    We examine normal-state quasiparticle excitations along the Γ -M cut in momentum space for the putative p -wave superconductor Sr2RuO4 on the basis of fluctuation exchange approximation calculations. We take as input first-principles derived parameters for the band structure and spin-orbit and electron-electron interactions. The numerical results are in excellent agreement with data from photoemission experiments and provide insight into the underlying quasiparticle properties. We find that, despite the correlation-induced effective mass increase near the Fermi surface, the full β and γ bandwidths are, if anything, increased by correlations. Furthermore, for the γ band we find anomalous lifetime broadening and a significant temperature of variation of unoccupied state quasiparticle energies for temperatures between 25 and 100 K, both of which are accounted for by the momentum dependence of the electron self-energy. In addition to aiding our understanding of experimental data, these results point to the challenge of assigning appropriate Fermi-liquid parameters or momentum-independent self-energies for schemes that require such approximations in order to model Sr2RuO4 .

  4. Surface noble metal modified PdM/C (M = Ru, Pt, Au) as anode catalysts for direct ethanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Han; Huang, Tao, E-mail: huangt@fudan.edu.cn; Yu, Aishui, E-mail: asyu@fudan.edu.cn

    2016-08-15

    In this article, we studied the surface noble metal modification on Pd nanoparticles, other than the homogeneous or core-shell structure. The surface modification will lead to the uneven constitution within the nanoparticles and thus more obvious optimization effect toward the catalyst brought by the lattice deformation. The surface of the as-prepared Pd nanoparticles was modified with Ru, Pt or Au by a moderate and green approach, respectively. XPS results confirm the interactive electron effects between Pd and the modified noble metal. Electrochemical measurements show that the surface noble metal modified catalysts not only show higher catalytic activity, but also better stability and durability. The PdM/C catalysts all exhibit good dispersion and very little agglomeration after long-term potential cycles toward ethanol oxidation. With only 10% metallic atomic ratio of Au, PdAu/C catalyst shows extraordinary catalytic activity and stability, the peak current reaches 1700 mA mg{sup −1} Pd, about 2.5 times that of Pd/C. Moreover, the PdAu/C maintains 40% of the catalytic activity after 4500 potential cycles. - Highlights: • Pd-based catalysts with complicated exposed facets. • Much enhanced electrocatalytic activity and stability with about 10% noble metal M (M = Ru, Pt, Au) on Pd nanoparticles. • The outstanding electrocatalytic performance of PdAu/C towards ethanol oxidation after the Au modification.

  5. Magnetic dichroism and magnetization studies of Eu_2-xCe_xRuSr_2Cu_2O_10, Gd_2RuSr_2Cu_2O_10 and Eu_1.5Ce_0.5Nb_1-xRu_xCu_2O_10 systems

    Science.gov (United States)

    Hirai, Y.; Frazer, B. H.; Rast, S.; Felner, I.; Asaf, U.; Schmauder, T.; Onellion, M.

    2000-03-01

    We report on photoabsorption and magnetic dichroism measurements of several polycrystalline ruthocuprate samples. The pure Ru-containing compounds exhibit ferromagnetic order, with metallic behavior and superconductivity depending on the rare earth and the oxygen content. We report on as-prepared, hydrogen-loaded, and oxygen-annealed polycrystalline samples. The Nb-Ru series changes from purely supersonducting (Nb) to both ferromagnetic and superconducting (Ru). The photoabsorption and magnetic dichroism data are compared to reference SrRuO3 samples. We obtain information on the O1s pre-edge feature, and the magnetic moment carried by the Ru and Nb atoms under the various conditions studied.

  6. Is the semi-regular variable RU Vulpeculae undergoing a helium-shell flash?

    Science.gov (United States)

    Uttenthaler, S.; Greimel, R.; Templeton, M.

    2016-03-01

    The semi-regular variable star RU Vulpeculae (RU Vul) is being observed visually since 1935. Its pulsation period and amplitude are declining since ˜ 1954. A leading hypothesis to explain the period decrease in asymptotic giant branch (AGB) stars such as RU Vul is an ongoing flash of the He-burning shell, also called a thermal pulse (TP), inside the star. In this paper, we present a CCD photometric light curve of RU Vul, derive its fundamental parameters, and test if the TP hypothesis can describe the observed period decline. We use CCD photometry to determine the present-day pulsation period and amplitude in three photometric bands, and high-resolution optical spectroscopy to derive the fundamental parameters. The period evolution of RU Vul is compared to predictions by evolutionary models of the AGB phase. We find that RU Vul is a metal-poor star with a metallicity [M/H]=-1.59±0.05 and an effective surface temperature of T_eff=3634±20 K. The low metallicity of RU Vul and its kinematics indicate that it is an old, low-mass member of the thick disc or the halo population. The present day pulsation period determined from our photometry is ˜ 108 d, the semi-amplitude in the V-band is 0.39±0.03 mag. The observed period decline is found to be well matched by an evolutionary AGB model with stellar parameters comparable to those of RU Vul. We conclude that the TP hypothesis is in good agreement with the observed period evolution of RU Vul. Based on observations made with the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.

  7. Critical Behaviour of Sintered SrRuO3

    Institute of Scientific and Technical Information of China (English)

    侯登录; 姜恩永; 李凤舞; 白海力; 周学志; Henry KUNKEL; Gwyn WILLIAMS

    2002-01-01

    From the measurements of the ac susceptibility of SrRuO3, we determine the critical temperature Tc = 159.7 ±0.2 K and critical exponents δ= 2.50 + 0.15 (from the critical isotherm) or δ= 3.17 ± 0.20 (from magnetization versus magnetic field at Curie temperature), γ + β= 1.50 ± 0.05 (from the temperature dependence of the internal field of the crossover line), and γ= 0.96 ± 0.05 (from the temperature dependence of the susceptibility along the same line). These exponent values are very close to those predicted by the mean field model.

  8. Aqueous Synthesis of Ru Doped Hematite Nanostructures: A Morphological, Structural, Optical, and Magnetic Study

    Directory of Open Access Journals (Sweden)

    Ceboliyozakha Leonard Ndlangamandla

    2015-01-01

    Full Text Available Hematite nanorods doped with ruthenium were successfully deposited on fluorine doped tin oxide (FTO glass substrates using aqueous chemical growth. Using complementary surface/interface investigation techniques, the Ru incorporation in the Ru-α-Fe2O3 nanorods was evidenced. The optical band gap was found to be Ru doping concentration dependent: varying from 2.32 (2 to 2.47 (2 eV. These band gap values are well suited for the targeted water splitting process without application of an external bias.

  9. Controle ativo de ruído em dutos utilizando processadores digitais de sinais

    OpenAIRE

    Delfino, Leandro César

    2005-01-01

    Ruídos acústicos são conhecidos como fontes de poluição sonora que podem causar efeitos adversos na vida humana. Para solucionar estes problemas, interesse considerável tem sido mostrado em Controle Ativo de Ruído. O intuito deste trabalho é estudar e analisar os principais algoritmos de Controle Ativo de Ruído presentes na literatura, incluindo algoritmos de malha aberta (Feedfoward) e de malha fechada (Feedback), bem como um sistema híbrido que utilize os dois conceitos. O...

  10. Controle ativo de ruído em dutos utilizando processadores digitais de sinais

    OpenAIRE

    Delfino, Leandro César

    2005-01-01

    Ruídos acústicos são conhecidos como fontes de poluição sonora que podem causar efeitos adversos na vida humana. Para solucionar estes problemas, interesse considerável tem sido mostrado em Controle Ativo de Ruído. O intuito deste trabalho é estudar e analisar os principais algoritmos de Controle Ativo de Ruído presentes na literatura, incluindo algoritmos de malha aberta (Feedfoward) e de malha fechada (Feedback), bem como um sistema híbrido que utilize os dois conceitos. O...

  11. All-trans-[ClRu(II)(py)4(NC)Ru(II)(py)4(CN)Ru(II)(py)4(NO)](PF6)4: a redox-active 2-donor/1-acceptor system based on the electrophilic {RuNO}6 motif.

    Science.gov (United States)

    De Candia, Ariel G; Singh, Priti; Kaim, Wolfgang; Slep, Leonardo D

    2009-01-19

    The new linear homotrinuclear compound trans-[ClRu(II)(py)(4)(NC)Ru(II)(py)(4)(CN)Ru(II)(py)(4)(NO)](PF(6))(4) was prepared by reaction between the nitro complex trans-[(NC)Ru(II)(py)(4)(CN)Ru(II)(py)(4)(NO(2))](+) and the solvento complex obtained by reaction between [ClRu(II)(py)(4)(NO)](3+) and N(3)(-) in acetone. The trans-[ClRu(II)(py)(4) (NC)Ru(II)(py)(4)(CN)Ru(II)(py)(4)(NO)](4+) ion (I) has been characterized by (1)H NMR and IR spectroscopy (nu(NO) = 1919 cm(-1)). This species displays intense electronic absorptions in the visible region which can be assigned to donor-acceptor charge-transfer transitions (DACT) involving {RuNO}(6)-centered acceptor orbitals and donor orbitals located on the two different neighboring metal centers at ca. 6.7 and 12.6 A distance from the metal in the {RuNO}(6) fragment. Addition of OH(-) to I generated the nitro complex with a second-order rate constant of (12.5 +/- 0.2) x 10(3) M(-1) s(-1) (25 degrees C). Cyclic voltammetry experiments complemented by spectroelectrochemistry in the UV-vis-NIR region reveal that I can be reversibly reduced at 0.49 or 0.20 V vs AgCl/Ag for acetonitrile and water, respectively, and oxidized at 0.71 or 0.57 V vs AgCl/Ag. The spectroscopic and spectroelectrochemical information (UV-vis-NIR, X-band EPR) supplemented with electronic structure computation (DFT) reveals that the one-electron reduction is centered on the nitrosyl moiety to yield a {RuNO}(7) species, while oxidation occurs on the chlororuthenium side of the molecule. Both processes yield significant changes of the electronic spectra which are discussed in parallel with the electronic structure picture as obtained by DFT.

  12. Oxidation resistance and microstructure of Ru-capped extreme ultraviolet lithography multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bajt, S; Dai, Z; Nelson, E J; Wall, M A; Alameda, J B; Nguyen, N; Baker, S L; Robinson, J C; Taylor, J S; Aquila, A; Edwards, N V

    2005-06-15

    The oxidation resistance of protective capping layers for extreme ultraviolet lithography (EUVL) multilayers depends on their microstructure. Differently prepared Ru-capping layers, deposited on Mo/Si EUVL multilayers, were investigated to establish their baseline structural, optical, and surface properties in as-deposited state. The same capping layer structures were then tested for their thermal stability and oxidation resistance. The best performing Ru-capping layer structure was analyzed in detail with transmission electron microscopy (TEM). As compared to other Ru capping layers preparations studied here it is the only one that shows grains with preferential orientation. This information is essential for modeling and performance optimization of EUVL multilayers.

  13. Optical Properties of Ru(bipy)2(dppx)2 + in Different Environments

    Institute of Scientific and Technical Information of China (English)

    CHEN Fang; Al Xin-ping; HE Zhi-ke

    2005-01-01

    The emission spectra of Ru(bipy)2 (dppx)2+ in different environments has been studied. It was found that the solvent polarity and the ability of donating and transferring proton are the important factors in predicting luminescence intensity in different systems. The increasing content of water in the organic solutions of Ru(bipy)2 (dppx)2+ leads to decrease in emission intensity that follows the Perrin sphere of quenching model. The effect of base content of DNA on the fluorescence spectra of Ru (bipy)2 (dppx)2+ has also been studied.

  14. Neutron activation analysis and Mossbauer spectroscopy research on coloring mechanism of Chinese Ru porcelain

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The characteristic spectrum and its main wavelength of Ru porcelain glaze are measured by color difference instrument to determine the relations between glaze color and its main wavelength. The content of the 30 coloring elements in Ru porcelain is determined by neutron activation analysis (NAA), which showed that iron is the major coloring element. M?ssbauer spectroscopy analysis shows that the iron element in the glaze exists in the form of structural iron (Fe2+, Fe3+). The quantitative relationship between the main wavelength of glaze in various colors and the relative content of structural iron (Fe2+/Fe3+) is determined. Thus the coloring mechanism of Ru porcelain is investigated entirely.

  15. Strong anisotropy within a Heisenberg model in the Jeff=1/2 insulating state of Sr2Ir0.8Ru0.2O4

    Science.gov (United States)

    Calder, S.; Kim, J. W.; Taylor, A. E.; Upton, M. H.; Casa, D.; Cao, Guixin; Mandrus, D.; Lumsden, M. D.; Christianson, A. D.

    2016-12-01

    The dispersive magnetic excitations in Sr2IrO4 have previously been well described within an isospin-1/2 Heisenberg model on a square lattice that revealed parallels with La2CuO4 . Here we investigate the inelastic spectra of Sr2Ir0.8Ru0.2O4 with resonant inelastic x-ray scattering (RIXS) at the Ir L3 edge. The results are well described using linear spin-wave theory within a similar Heisenberg model applicable to Sr2IrO4 ; however, the disorder induced by the substitution of 20 %Ir4 + ions for Ru4 + removes longer range exchange interactions. A large spin gap (40 meV) is measured indicating strong anisotropy from spin-orbit coupling that is manifest due to the altered magnetic structure in Sr2Ir0.8Ru0.2O4 with c -axis aligned moments compared to the basal plane moments in the parent. Collectively the results indicate the robustness of a Heisenberg model description even when the magnetic structure is altered and the Jeff=1 /2 moments are diluted.

  16. Structural and chelation behaviors of new Ru(II), Pt(IV) and Ir(III) gatifloxacin drug complexes: Spectroscopic characterizations

    Science.gov (United States)

    Alghamdi, Mohammed T.; Alsibaai, A. A.; El-Shahawi, M. S.; Refat, Moamen S.

    2017-02-01

    The interaction between gatifloxacin drug (GAT) with some transition metals (Ru(III), Pt(IV) and Ir(III)) yield the complexes of formulas [Ru(GAT-NH4)(Cl)3(H2O)2], [Pt(GAT-NH4)2(Cl)4]·3H2O and [Ir(GAT-NH4)2(Cl)2(H2O)2]·Cl·2H2O at pH = 7-8. The composition of the GAT complexes was confirmed by elemental data. The IR frequencies reveal the coordination of the GAT with metal ions and the coordination mode of the sbnd N atom of 3-methylpiperazinyl moiety to metal. XRD pattern show isomorphism among the complexes with similar chelation behavior. Scanning electron microscope (SEM) and transmission electron microscopy (TEM) were used to identify the particle size of GAT complexes. The thermal data reveals that various steps of decomposition of the complexes to form their metal oxide as final product. The electronic spectra and the magnetic susceptibility values reveal that the coordination and geometry of Ru3+, Pt4+ and Ir3+ complexes possess distorted octahedral geometry with six number of coordination. Thermodynamic parameters (E*, ΔS*, ΔH* and ΔG*) were calculated from TG curves dependent on Coats-Redfern and Horowitz-Metzeger non-isothermal methods.

  17. A Novel Electrochemical Sensor Based on [Ru(NH3)6]Cl3 as a Redox Indicator for the Detection of G-G Mismatched DNA.

    Science.gov (United States)

    Zhu, Xiaoqian; Huang, Min; Li, Jiao; He, Hanping; Zhang, Xiuhua; Wang, Shengfu

    2017-01-01

    In this paper, a novel electrochemical sensor was developed for the rapid detection of G-G mismatched DNA based on hexaammineruthenium(III) chloride ([Ru(NH3)6]Cl3) as a redox indicator. The sensor platform was constructed by immobilizing small molecules (NC-linker) on the gold electrode via amide bonds. The as-prepared NC-linker as the nucleic acids recognition molecule can interact with the G base of DNA. After the sensor was incubated with G-G mismatched DNA, the double-stranded DNA (dsDNA) acted as carriers of the signal tags-[Ru(NH3)6]Cl3, which resulted in a remarkable electrochemical signal. More binding of [Ru(NH3)6]Cl3 led to increases of the electrochemical signal. Other mismatched DNA produced only a low response, as well as complementary DNA. Thus G-G mismatched DNA can be easily discriminated from other mismatched and complementary DNA based on the sensor. Furthermore, the method was simple, rapid and repeatable for the detection of G-G mismatched DNA. The selective detection of target dsDNA was achieved by a relative current ratio of the target and control DNA. These results demonstrated that this strategy could provide great promise for the rapid and specific detection of other sequence-specific DNA.

  18. Insights into dehydrogenative coupling of alcohols and amines catalyzed by a (PNN)-Ru(II) hydride complex: unusual metal-ligand cooperation.

    Science.gov (United States)

    Zeng, Guixiang; Li, Shuhua

    2011-11-07

    Density functional theory calculations were performed to elucidate the mechanism of dehydrogenative coupling of primary alcohols and amines mediated by a PNN-Ru(II) hydride complex (PNN = (2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)pyridine)). A plausible reaction pathway was proposed which contains three stages: (1) The alcohol dehydrogenation reaction to generate the aldehyde and H(2); (2) The aldehyde-amine condensation reaction to form the hemiaminal intermediate; (3) The dehydrogenation process of the hemiaminal intermediate to yield the final amide product with the liberation of H(2). The first and third stages occur via a similar pathway: (a) Proton transfer from the substrate to the PNN ligand; (b) Intramolecular rearrangement of the deprotonated substrate to form an anagostic complex; (c) Hydride transfer from the deprotonated substrate to the Ru center to yield the trans-dihydride intermediate and the aldehyde (or amide); (d) Benzylic proton migration from the PNN ligand to the metal center forming a dihydrogen complex and subsequent H(2) liberation to regenerate the catalyst. In all these steps, the metal-ligand cooperation plays an essential role. In proton transfer steps (a) and (d), the metal-ligand cooperation is achieved through the aromatization/dearomatization processes of the PNN ligand. While in steps (b) and (c), their collaboration are demonstrated by the formation of an anagostic interaction between Ru and the C-H bond and two ionic hydrogen bonds supported by the PNN ligand.

  19. Approximative treatment of 5f-systems with partial localization due to intra-atomic correlations

    NARCIS (Netherlands)

    Runge, E; Fulde, P; Efremov, DV; Hasselmann, N; Zwicknagl, G

    2004-01-01

    Increasing experimental and theoretical evidence points towards a dual nature of the 5f electrons in actinide-based strongly correlated metallic compounds, with some 5f electrons being localized and others delocalized. In a recent paper [Phys. Rev. B 69, 115114 (2004)], we suggested the interplay of

  20. Half metallicity and magnetic properties of CrO{sub 2} doped with Ti, Sn or Ru

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, C. [The State Key Laboratory of Refractories and Metallurgy, School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Lu, Z., E-mail: zludavid@live.com [The State Key Laboratory of Refractories and Metallurgy, School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Liu, S. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Gan, Z.; Guo, F. [The State Key Laboratory of Refractories and Metallurgy, School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Xiong, R., E-mail: xiongrui@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Mei, X. [School of Science, Wuhan University of Technology, Wuhan 430070 (China); Liu, H. [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Shi, J., E-mail: jshi@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072 (China)

    2016-11-01

    It is possible to stabilize CrO{sub 2} internally by doping with element such as Ti, Sn or Ru which has stable rutile structured oxide. However, the half metallicity and magnetic properties of CrO{sub 2} may also change when doped with different elements. In this study, by using first principle method, the electronic structure and magnetic properties of CrO{sub 2} doped with different amounts and different types (Ti, Sn or Ru) of dopants were studied. It was found that when doped with Ti or Sn, the half metallicity of CrO{sub 2} will keep intact even at very high dopant concentration, while for Ru-doped CrO{sub 2}, the half metallicity will only be maintained at low Ru concentration. Besides, the half metallicity of Ru-doped CrO{sub 2} also depends on the relative positions of Ru atoms – the half metallicity may be destroyed even at low Ru concentration if two Ru ions are very close to each other. The magnetic properties of doped CrO{sub 2} also show dependence on dopant concentration and dopant type. The magnetocrystalline anisotropy (MAC) of Ru-doped is found to be very sensitive to both Ru concentration and relative positions of Ru atoms. Large MAC may be induced by Ru doping. - Highlights: • First principle study of Ti, Sn or Ru doped CrO{sub 2} found that the half metallic nature of CrO{sub 2} will keep intact when doped with Ti or Sn, while it may be destroyed when doped with Ru. • The half metallicity of Ru-doped CrO{sub 2} depends on Ru concentration as well as the relative positions of Ru ions. • The magentic properties of doped CrO{sub 2} show dependence on both dopant concentration and dopant type. • Large magnetocrystalline anisotropy may be induced in Ru-doped CrO{sub 2}.

  1. Studies of quadrupole collectivity in the {gamma}-soft {sup 106}Ru

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Vega, M.; Taylor, R.B.E.; Fogelberg, B.; Lindroth, A. [Uppsala University, Department of Nuclear and Particle Physics, P.O. Box 535, Uppsala (Sweden); Mach, H. [Uppsala University, Department of Nuclear and Particle Physics, P.O. Box 535, Uppsala (Sweden); University of Notre Dame, Institute for Structure and Nuclear Astrophysics, Notre Dame, IN (United States); Aas, A.J. [University of Oslo, Department of Chemistry, P.O. Box 1033, Blindern (Norway); Dendooven, P.; Honkanen, A.; Huhta, M.; Lhersonneau, G.; Oinonen, M.; Parmonen, J.M.; Penttilae, H.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics, P.O. Box 35, Jyvaeskylae (Finland); Persson, J.R. [University of Birmingham, School of Physics and Space Research, Birmingham (United Kingdom); Kurpeta, J. [University of Warsaw, Faculty of Physics, Warsaw (Poland)

    2008-02-15

    Various alternative models were used to describe the structure of {sup 106}Ru. For example, the General Collective Model (GCM) predicts shape-coexistence for {sup 106}Ru with a spherical and a triaxial minimum and strongly mixed structures, while in the IBA-2 calculations, where {sup 106}Ru was considered as transitional from vibrational U(5) to {gamma}-soft O(6), no need was found to include the shape-coexisting configurations. In order to provide additional constraints on the model interpretations, we have applied the Advanced Time-Delayed (ATD) {beta}{gamma}{gamma}(t) method to measure the level lifetimes of the excited levels in {sup 106}Ru. The new results include the half-lives of T{sub 1/2}=183(3) ps and 7.5(30) ps for the 2{sup +}{sub 1} and 2{sup +}{sub 2} states, respectively. (orig.)

  2. Mesoporous Pt and Pt/Ru alloy electrocatalysts for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Planes, Gabriel A. [Departamento de Quimica, Facultad de Ciencias Exactas, Fisicoquimicas y Naturales, Universidad Nacional de Rio Cuarto, Agencia Postal No 3, 5800, Rio Cuarto (Argentina); Williams, Federico J. [Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina); Soler-Illia, Galo J.A.A. [Gerencia de Quimica, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Corti, Horacio R. [Grupo de Celdas de Combustible, Departamento de Fisica de la Materia Condensada, Centro Atomico Constituyentes, CNEA. Av. General Paz 1499 (1650), San Martin, Buenos Aires (Argentina); Departamento de Quimica Inorganica, Analitica y Quimica-Fisica, INQUIMAE CONICET, Facultad Ciencias Exactas y Naturales, Pabellon 2, Ciudad Universitaria, Buenos Aires (Argentina)

    2011-02-15

    Mesoporous Pt and Pt/Ru catalysts with 2D-hexagonal mesostructure were synthesized using a triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (Pluronic F127 {sup registered}) template, on a gold support. Large electrochemical surface areas were observed for the catalysts prepared at high overpotentials. Compared to the Pt catalyst, the Pt/Ru alloy containing 3 at% of Ru exhibited lower onset potential and more than three times the limit mass activity for methanol oxidation. This behavior is assigned to the larger pore size of the mesoporous Pt and Pt/Ru catalysts obtained with this template that seems to improve the methanol accessibility to the active sites compared to those obtained using lyotropic liquid crystals. (author)

  3. Elastic properties of Re-Ru{sub 4}Sb{sub 12} (Re; La, Pr)

    Energy Technology Data Exchange (ETDEWEB)

    Kumagai, T.; Nakanishi, Y.; Sugawara, H.; Sato, H.; Yoshizawa, M

    2003-05-01

    We have investigated elastic properties of the filled skutterudite compounds LaRu{sub 4}Sb{sub 12} and PrRu{sub 4}Sb{sub 12} by means of ultrasonic measurement. No elastic softening towards low temperature in both (C{sub 11}-C{sub 12})/2 and C{sub 44}, has been observed in PrRu{sub 4}Sb{sub 12}. The obtained result suggests that Pr{sup 3+} {gamma}{sub 1} singlet ground state is realized in PrRu{sub 4}Sb{sub 12} under the crystalline electric field (CEF). It also indicates that {gamma}{sub 1} singlet ground state is possible in other Pr-based filled skutterudite compounds.

  4. Comparative antibacterial activity of the aminothiazolyl cephalosporin RU 29,246.

    Science.gov (United States)

    Qadri, S M; Ueno, Y; Saldin, H; Tullo, D D; Lee, G C

    1993-01-01

    A total of 1,007 clinical isolates from a tertiary care center were tested against RU 29,246, ampicillin, cephalothin, cefoxitin, ceftazidime, Augmentin, oxacillin, piperacillin, gentamicin, amikacin and vancomycin. Bacteria tested consisted of 479 strains of Enterobacteriaceae, 64 pseudomonads, 18 Xanthomonas, 42 other gram-negative bacilli, 56 enterococci and 348 isolates of staphylococci. RU 29,246 showed excellent in vitro activity inhibiting > 90% of Escherichia coli, Klebsiella pneumoniae, K. oxytoca, Enterobacter, Proteus mirabilis, Providencia, Morganella, Salmonella, Shigella, Aeromonas hydrophila, and methicillin-susceptible Staphylococcus aureus at an MIC of 0.5-1.0 mg/l. Seventy-seven percent coagulase-negative staphylococci had an MIC of 1.0-4.0 mg/l. All strains of Pseudomonas aeruginosa and X. maltophilia were resistant to RU 29,246. Fifty-six percent of the enterococcal isolates were inhibited by 1.0-16.0 mg/l of RU 29,246.

  5. Hydrogenation of coumarin to octahydrocoumarin over a Ru/C catalyst

    Institute of Scientific and Technical Information of China (English)

    Dana Bílková; Petr Jansa; Iva Paterová; Libor Červený

    2015-01-01

    The production of octahydrocoumarin, which can serve as a replacement for toxic coumarin, was investigated using 5% Ru on active carbon (Ru/C) as the catalyst for the hydrogenation of couma-rin. The hydrogenation was studied by optimizing the reaction conditions (pressure, solvent and coumarin concentration). The activity and selectivity of the Ru/C catalyst were compared for dif-ferent solvents. The mechanism of coumarin hydrogenation was deduced. The formation of side products was explained. The optimal hydrogenation reaction conditions were: 130 °C, 10 MPa, 60 wt% coumarin in methanol, and 0.5 wt% (based on coumarin) of Ru/C catalyst. At the complete conversion of coumarin, the selectivity to the desired product was 90%.

  6. Cyclic-Oxidation Behavior of Multilayered Pt/Ru-Modified Aluminide Coating

    Institute of Scientific and Technical Information of China (English)

    Yingxue Song; Hideyuki Murakami; Chungen Zhou

    2011-01-01

    Multilayered Pt/Ru modified aluminide coating for thermal barrier coating (TBC) systems has been investigated. 2 μm Pt+2μm Ru+2 μm Pt was first deposited on nickel-base superalloy DZ125 by electrodeposition, and then the coating was treated by annealing and a conventional pack-cementation aluminizing process. The cyclic oxidation tests were carried out at 1423 K in air. It was found that the thermal cyclic oxidation resistance of Pt/Ru-modified aluminide coating was comparable to that of Pt-modified aluminide coating, which was much better than simply aluminized DZ125. The addition of Ru to Pt-modified aluminide coating increased the resistance to rumpling. The microstructures and phase constitutions of the coating before and after oxidation were investigated.

  7. Electronic, thermodynamic and elastic properties of pyrite RuO_2

    Institute of Scientific and Technical Information of China (English)

    Yang Ze-Jin; Guo Yun-Dong; Wang Guang-Chang; Li Jin; Dai Wei; Liu Jin-Chao; Cheng Xin-Lu; Yang Xiang-Dong

    2009-01-01

    This paper calculates the elastic, thermodynamic and electronic properties of pyrite (Pa3) RuO_2 by the plane-wave pseudopotential density functional theory (DFT) method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle-ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO_2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO_2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO_2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.

  8. PtRu/C Electrocatalysts Prepared Using Gamma and Electron Beam Irradiation for Methanol Electrooxidation

    Directory of Open Access Journals (Sweden)

    Dionisio F. Silva

    2012-01-01

    Full Text Available PtRu/C electrocatalysts (carbon-supported PtRu nanoparticles were prepared in a single step submitting water/2-propanol mixtures containing Pt(IV and Ru(III ions and the carbon support to gamma and electron beam irradiation. The electrocatalysts were characterized by energy dispersive X-ray analysis (EDX, X-ray diffraction (XRD, transmission electron microscopy (TEM, and cyclic voltammetry and tested for methanol electrooxidation. PtRu/C electrocatalyst can be prepared in few minutes using high dose rate electron beam irradiation while using low dose rate gamma irradiation some hours were necessary to prepare it. The obtained materials showed the face-centered cubic (fcc structure of Pt and Pt alloys with average nanoparticle sizes of around 3 nm. The material prepared using electron beam irradiation was more active for methanol electrooxidation than the material prepared using gamma irradiation.

  9. CANDU RU fuel manufacturing basic technology development and advanced fuel verification tests

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hwan; Chang, S.K.; Hong, S.D. [and others

    1999-04-01

    A PHWR advanced fuel named the CANFLEX fuel has been developed through a KAERI/AECL joint Program. The KAERI made fuel bundle was tested at the KAERI Hot Test Loop for the performance verification of the bundle design. The major test activities were the fuel bundle cross-flow test, the endurance fretting/vibration test, the freon CHF test, and the fuel bundle heat-up test. KAERI also has developing a more advanced PHWR fuel, the CANFLEX-RU fuel, using recovered uranium to extend fuel burn-up in the CANDU reactors. For the purpose of proving safety of the RU handling techniques and appraising feasibility of the CANFLEX-RU fuel fabrication in near future, a physical, chemical and radiological characterization of the RU powder and pellets was performed. (author). 54 refs., 46 tabs., 62 figs.

  10. Structure, physical properties, and applications of SrRuO3 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Siemons, Wolter [ORNL; Koster, Gertjan [University of Twente, Enschede, Netherlands; Rijnders, Guus [MESA+ University of Twente, Enschede, Netherlands; Klein, Lior [Institute of Nanotechnology Bar-Ilan University, Ramat-Gan, Israel; Dodge, J. Steven [Simon Fraser University, Canada; Eom, Professor Chang-Beom [University of Wisconsin, Madison; Blank, Dave H. A. [University of Twente, Enschede, Netherlands; Beasley, Malcolm R [Stanford University

    2012-01-01

    SrRuO{sub 3} is endowed with three remarkable features. First, it is a moderately correlated material that exhibits several novel physical properties; second, it permits the epitaxial growth of essentially single-crystal films; and third, because it is a good conductor, it has attracted interest as a conducting layer in epitaxial heterostructures with a variety of functional oxides. In this review, the present state of knowledge of SrRuO{sub 3} thin films is summarized. Their role as a model system for studying magnetism and electron transport characterized by intermediate electron correlation and large magnetocrystalline anisotropy is demonstrated. The materials science of SrRuO{sub 3} thin film growth is reviewed, and its relationship to electronic, magnetic, and other physical properties is discussed. Finally, it is argued that, despite all that has been learned, a comprehensive understanding of SrRuO{sub 3} is still lacking and challenges remain.

  11. Search for 2\\beta\\ decays of 96Ru and 104Ru by ultra-low background HPGe gamma spectrometry at LNGS: final results

    CERN Document Server

    Belli, P; Cappella, F; Cerulli, R; Danevich, F A; d'Angelo, S; Incicchitti, A; Kovtun, G P; Kovtun, N G; Laubenstein, M; Poda, D V; Polischuk, O G; Shcherban, A P; Solopikhin, D A; Suhonen, J; Tretyak, V I

    2013-01-01

    An experiment to search for double beta decay processes in 96Ru and 104Ru, which are accompanied by gamma rays, has been realized in the underground Gran Sasso National Laboratories of the I.N.F.N. (Italy). Ruthenium samples with masses of about (0.5-0.7) kg were measured with the help of ultra-low background high purity Ge gamma ray spectrometry. After 2162 h of data taking the samples were deeply purified to reduce the internal contamination of 40K. The last part of the data has been accumulated over 5479 h. New improved half life limits on 2\\beta+/\\epsilon \\beta+/2\\epsilon\\ processes in 96Ru have been established on the level of 10^{20} yr, in particular for decays to the ground state of 96Mo: T1/2(2\

  12. Two-step hydrothermal synthesis of Ru-Sn oxide composites for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Chi-Chang; Chang, Kuo-Hsin; Wang, Chen-Ching [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China)

    2007-03-20

    A two-step hydrothermal process was developed to synthesize hydrous 30RuO{sub 2}-70SnO{sub 2} composites with much better capacitive performances than those fabricated through the normal hydrothermal process, co-annealing method, or modified sol-gel procedure. A very high specific capacitance of RuO{sub 2} (C{sub S,Ru}), ca. 1150 F g{sup -1}, was obtained when this composite was synthesized via this two-step hydrothermal process with annealing in air at 150 C for 2 h. The voltammetric currents of this annealed composite were found to be quasi-linearly proportional to the scan rate of CV (up to 500 mV s{sup -1}), demonstrating its excellent power property. From Raman, UV-vis spectroscopic and TEM analyses, the reduction in mean particulate size is clearly found for this two-step oxide composite, attributable to the co-precipitation of (Ru{sub {delta}}Sn{sub 1-{delta}})O{sub 2}.xH{sub 2}O onto partially dissolved SnO{sub 2}.xH{sub 2}O and the formation of (Ru{sub {delta}}Sn{sub 1-{delta}})O{sub 2}.xH{sub 2}O crystallites in the second step. This effect significantly promotes the utilization of RuO{sub 2} (i.e., very high C{sub S,Ru}). The excellent capacitive performances, very similar to that of RuO{sub 2}.xH{sub 2}O, suggest the deposition of RuO{sub 2}-enriched (Ru{sub {delta}}Sn{sub 1-{delta}})O{sub 2}.xH{sub 2}O onto SnO{sub 2}.xH{sub 2}O seeds as well as the individual formation of (Ru{sub {delta}}Sn{sub 1-{delta}})O{sub 2}.xH{sub 2}O crystallites in the second hydrothermal step. (author)

  13. Atomic force spectroscopy and density-functional study of graphene corrugation on Ru(0001)

    Science.gov (United States)

    Voloshina, Elena; Dedkov, Yuriy

    2016-06-01

    Graphene, the thinnest material in the world, can form moiré structures on different substrates, including graphite, h -BN, or metal surfaces. In such systems, the structure of graphene, i.e., its corrugation, as well as its electronic and elastic properties, are defined by the combination of the system geometry and local interaction strength at the interface. The corrugation in such structures on metals is heavily extracted from diffraction or local probe microscopy experiments, and it can be obtained only via comparison with theoretical data, which usually simulate the experimental findings. Here we show that graphene corrugation on metals can be measured directly employing atomic force spectroscopy, and the obtained value coincides with state-of-the-art theoretical results. The presented results demonstrate an unexpected space selectivity for the Δ f (z ) signal in the atomic force spectroscopy in the moiré graphene lattice on Ru(0001), which is explained by the different response of the graphene layer on the indentation process. We also address the elastic reaction of the formed graphene nanodoms on the indentation process by the scanning tip that is important for the modeling and fabrication of graphene-based nanoresonators on the nanoscale.

  14. Adsorption stages of O on Ru(0001) studied by means of scanning tunnelling microscopy

    CERN Document Server

    Meinel, K; Ammer, C; Beckmann, A; Neddermeyer, H

    1997-01-01

    The adsorption of O on Ru(0001) at a temperature of 400 K is studied in detail by means of scanning tunnelling microscopy (STM). With increasing O coverage, an ordered p(2x2) structure develops, followed by a p(2x1) structure. While the p(2x2) structure grows via island formation, the p(2x1) structure is abruptly formed by a disorder - order phase transition. After completion of the p(2x2) structure at a coverage of 0.25 ML, the surface develops a rough structure where the (2x2) units remain visible but appear with different heights. As the origin of this phenomenon, we propose additional O-O interactions and/or subsurface O due to the increase in O coverage. At coverages between 0.3 monolayer (ML) and 0.35 ML, different preformations of the p(2x1) structure are observed. First, small fragments of p(2x1) rows develop, which are randomly distributed over the surface and rotated by 120 deg. with respect to each other. They grow in one dimension and induce a criss-cross arrangement of linear chains of O atoms. T...

  15. Formation and nitrile hydrogenation performance of Ru nanoparticles on a K-doped Al2O3 surface.

    Science.gov (United States)

    Muratsugu, Satoshi; Kityakarn, Sutasinee; Wang, Fei; Ishiguro, Nozomu; Kamachi, Takashi; Yoshizawa, Kazunari; Sekizawa, Oki; Uruga, Tomoya; Tada, Mizuki

    2015-10-14

    Decarbonylation-promoted Ru nanoparticle formation from Ru3(CO)12 on a basic K-doped Al2O3 surface was investigated by in situ FT-IR and in situ XAFS. Supported Ru3(CO)12 clusters on K-doped Al2O3 were converted stepwise to Ru nanoparticles, which catalyzed the selective hydrogenation of nitriles to the corresponding primary amines via initial decarbonylation, the nucleation of the Ru cluster core, and the growth of metallic Ru nanoparticles on the surface. As a result, small Ru nanoparticles, with an average diameter of less than 2 nm, were formed on the support and acted as efficient catalysts for nitrile hydrogenation at 343 K under hydrogen at atmospheric pressure. The structure and catalytic performance of Ru catalysts depended strongly on the type of oxide support, and the K-doped Al2O3 support acted as a good oxide for the selective nitrile hydrogenation without basic additives like ammonia. The activation of nitriles on the modelled Ru catalyst was also investigated by DFT calculations, and the adsorption structure of a nitrene-like intermediate, which was favourable for high primary amine selectivity, was the most stable structure on Ru compared with other intermediate structures.

  16. RU28318, an Aldosterone Antagonist, in Combination with an ACE Inhibitor and Angiotensin Receptor Blocker Attenuates Cardiac Dysfunction in Diabetes

    Directory of Open Access Journals (Sweden)

    Ibrahim F. Benter

    2013-01-01

    Full Text Available Aims. We evaluated the effects of RU28318 (RU, a selective mineralocorticoid receptor (MR antagonist, Captopril (Capt, an angiotensin converting enzyme inhibitor, and Losartan (Los, an angiotensin receptor blocker, alone or in combination with ischemia/reperfusion- (I/R- induced cardiac dysfunction in hearts obtained from normal and diabetic rats. Methods. Isolated hearts were perfused for 30 min and then subjected to 30 min of global ischemia (I followed by a period of 30 min of reperfusion (R. Drugs were administered for 30 min either before or after ischemia. Drug regimens tested were RU, Capt, Los, RU + Capt, RU + Los, Capt + Los, and RU + Capt + Los (Triple. Recovery of cardiac hemodynamics was evaluated. Results. Recovery of cardiac function was up to 5-fold worse in hearts obtained from diabetic animals compared to controls. Treatment with RU was generally better in preventing or reversing ischemia-induced cardiac dysfunction in normal hearts compared to treatment with Capt or Los alone. In diabetic hearts, RU was generally similarly effective as Capt or Los treatment. Conclusions. RU treatment locally might be considered as an effective therapy or preventative measure in cardiac I/R injury. Importantly, RU was the most effective at improving -dP/dt (a measure of diastolic function when administered to diabetic hearts after ischemia.

  17. Catalytic Ammonia Decomposition over High-Performance Ru/Graphene Nanocomposites for Efficient COx-Free Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Gang Li

    2017-01-01

    Full Text Available Highly-dispersed Ru nanoparticles were grown on graphene nanosheets by simultaneously reducing graphene oxide and Ru ions using ethylene glycol (EG, and the resultant Ru/graphene nanocomposites were applied as a catalyst to ammonia decomposition for COx-free hydrogen production. Tuning the microstructures of Ru/graphene nanocomposites was easily accomplished in terms of Ru particle size, morphology, and loading by adjusting the preparation conditions. This was the key to excellent catalytic activity, because ammonia decomposition over Ru catalysts is structure-sensitive. Our results demonstrated that Ru/graphene prepared using water as a co-solvent greatly enhanced the catalytic performance for ammonia decomposition, due to the significantly improved nano architectures of the composites. The long-term stability of Ru/graphene catalysts was evaluated for COx-free hydrogen production from ammonia at high temperatures, and the structural evolution of the catalysts was investigated during the catalytic reactions. Although there were no obvious changes in the catalytic activities at 450 °C over a duration of 80 h, an aggregation of the Ru nanoparticles was still observed in the nanocomposites, which was ascribed mainly to a sintering effect. However, the performance of the Ru/graphene catalyst was decreased gradually at 500 °C within 20 h, which was ascribed mainly to both the effect of the methanation of the graphene nanosheet under a H2 atmosphere and to enhanced sintering under high temperatures.

  18. Investigation of the site preference in Mn{sub 2}RuSn using KKR-CPA-LDA calculation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ling; Liu, Bohua [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Luo, Hongzhi, E-mail: luo_hongzhi@163.com [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Meng, Fanbin; Liu, Heyan [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Liu, Enke; Wang, Wenhong; Wu, Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-05-15

    We investigated the site preference and atomic disorder between the A and C sites in Heusler alloy Mn{sub 2}RuSn by using the KKR-CPA-LDA method. It is found that, at ground state 0 K, the Hg{sub 2}CuTi-type (XA) structure is energetically favored, in which one Mn and one Ru occupy the A and C sites, respectively. The ground state energy of Mn{sub 2}RuSn increases with increasing degree of Mn (A)–Ru (C) atomic disorder. The equilibrium lattice constants also show a similar tendency. The Mn (A)–Ru (C) disorder lower the total spin moment effectively, which is 1.87 μ{sub B} in the XA structure and only 0.98 μ{sub B} in the L2{sub 1}B structure. In Mn{sub 2}RuSn with different degree of Mn (A)–Ru (C) atomic disorder, the total moments are always determined by the antiparallel aligned Mn (A, C) and Mn (B) spin moments. The saturated moment of Mn{sub 2}RuSn at 5 K is 1.68 μ{sub B}, which corresponds to ∼11% antisite Mn entering the C site. This Mn (A)–Ru (C) disorder in samples can be related to the contributions from entropy of mixing at elevated temperatures, especially when this sample is quenched from high temperatures. - Highlights: • Atomic disorder in Heusler alloy Mn{sub 2}RuSn has been investigated by the KKR-CPA method. • Hg{sub 2}CuTi-type structure is energetically favored in Mn{sub 2}RuSn. • Mn (A)–Ru (C) disorder obviously influence the magnetic properties of Mn{sub 2}RuSn.

  19. Magnetic properties of ultrathin Ni81Fe19 films with Ta and Ru capping layers.

    Science.gov (United States)

    Kezilebieke, S; Ali, M; Shadeke, B; Gunnella, R

    2013-11-27

    Magnetic properties of Ni81Fe19 (permalloy) ultrathin films with Ru and Ta capping layers (CLs) were investigated for applications to magnetic random access memory units (MRAM). The sample structure, which simulated an MRAM free layer, is Si- sub./SiO2/Ni81Fe19/Ru(Ta). The Ni81Fe19 thin films less than 3 nm thick with Ru CL show low coercive fields compared with the Ta capping layer. Both systems showed loss of momentum equivalent to magnetically dead layers of thickness (δ) ~0.6 nm for Ru cap layer and ~1.4 nm for Ta cap layer, respectively. Moreover, after annealing the thicknesses are slightly increased to an equivalent magnetic dead layer thickness of δ ~0:84 nm and ~1.80 nm for Ru and Ta CL, respectively. Our calculations showed that the presence of only 11% Ta concentration at the interface reduced the Ni momentum to zero, with the Ni–Ta coupling being anti-ferromagnetic; while 50% Ru intermixing at the interface reduced the Ni momentum to zero with the coupling between Ru and Ni being ferromagnetic. To find out more about the intermixing at the interface, the composition and chemical states were characterized by the x-ray photoelectron spectroscopy and peak decomposition technique. The result showed that the peak positions were different from the pure metallic case at the interface region, mainly because of the intermixing between two layers. In conclusion, the Ru capping layer might be important for MRAM use in terms of low coercive field and small δ layer thickness if compared with the Ta capping layer.

  20. Mixed phase Pt-Ru catalyst for direct methanol fuel cell anode by flame aerosol synthesis

    DEFF Research Database (Denmark)

    Chakraborty, Debasish; Bischoff, H.; Chorkendorff, Ib

    2005-01-01

    A spray-flame aerosol catalyzation technique was studied for producing Pt-Ru anode electrodes for the direct methanol fuel cell. Catalysts were produced as aerosol nanoparticles in a spray-flame reactor and deposited directly as a thin layer on the gas diffusion layer. The as-prepared catalyst......Ru1/Vulcan carbon. The kinetics of methanol oxidation on the mixed phase catalyst was also explored by electrochemical impedance spectroscopy. (c) 2005 The Electrochemical Society....

  1. Methane Direct Conversion on Mo/ZSM-5 Catalysts Modified by Pd and Ru

    Institute of Scientific and Technical Information of China (English)

    Priscila Dias Sily; Fabio Bellot Noronha; Fabio Barboza Passos

    2006-01-01

    The effect of addition of Ru and Pd to Mo/HZSM-5 catalysts used in the dehydroaromatization of methane was investigated. Catalytic tests and temperature-programmed oxidation results showed that Pd-based catalysts were more selective to naphthalene and suffered strong deactivation. The presence of Ru improved the activity and stability, with a decrease in the carbonaceous deposit probably because of a mechanism of protection of the Mo2C surface.

  2. Magnetic properties of ultrathin Ni81Fe19 films with Ta and Ru capping layers

    Science.gov (United States)

    Kezilebieke, S.; Ali, M.; Shadeke, B.; Gunnella, R.

    2013-11-01

    Magnetic properties of Ni81Fe19 (permalloy) ultrathin films with Ru and Ta capping layers (CLs) were investigated for applications to magnetic random access memory units (MRAM). The sample structure, which simulated an MRAM free layer, is Si- sub./SiO2/Ni81Fe19/Ru(Ta). The Ni81Fe19 thin films less than 3 nm thick with Ru CL show low coercive fields compared with the Ta capping layer. Both systems showed loss of momentum equivalent to magnetically dead layers of thickness (δ) ˜0.6 nm for Ru cap layer and ˜1.4 nm for Ta cap layer, respectively. Moreover, after annealing the thicknesses are slightly increased to an equivalent magnetic dead layer thickness of δ ˜ 0.84 nm and ˜1.80 nm for Ru and Ta CL, respectively. Our calculations showed that the presence of only 11% Ta concentration at the interface reduced the Ni momentum to zero, with the Ni-Ta coupling being anti-ferromagnetic; while 50% Ru intermixing at the interface reduced the Ni momentum to zero with the coupling between Ru and Ni being ferromagnetic. To find out more about the intermixing at the interface, the composition and chemical states were characterized by the x-ray photoelectron spectroscopy and peak decomposition technique. The result showed that the peak positions were different from the pure metallic case at the interface region, mainly because of the intermixing between two layers. In conclusion, the Ru capping layer might be important for MRAM use in terms of low coercive field and small δ layer thickness if compared with the Ta capping layer.

  3. Solar water disinfection by singlet oxygen photogenerated with polymer-supported Ru(II) sensitizers

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Hernandez, M. Emilia; Manjon, Francisco; Garcia-Fresnadillo, David; Orellana, Guillermo [Laboratory of Applied Photochemistry, Department of Organic Chemistry, Faculty of Chemistry, Universidad Complutense de Madrid, 28040 Madrid (Spain)

    2006-10-15

    Using Escherichia coli and Enterococcus faecalis as model microorganisms, water disinfection has been demonstrated with singlet molecular oxygen (a reactive oxygen species) photogenerated by polymer-supported Ru(II) sensitizers and solar light. Both laboratory and sunlight tests were performed. The Ru(II) polypyridyl complex and its insoluble support have been optimized to provide maximum efficiency of singlet oxygen production and contact with the microorganism. (author)

  4. Localized-itinerant dichotomy and unconventional magnetism in SrRu2O6

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masayuki [Osaka University, Japan; Trivedi, Nandini [Ohio State University; Arita, Ryotaro [RIKEN Center for Emergent Matter Science (CEMS), Japan; Okamoto, Satoshi [ORNL; Yan, Jiaqiang [ORNL

    2017-09-01

    Electron correlations tend to generate local magnetic moments that usually order if the lattices are not too frustrated. The hexagonal compound SrRu$_2$O$_6$ has a relatively high N{\\'e}el temperature but small local moments, which seem to be at odds with the nominal valence of Ru$^{5+}$ in the $t_{2g}^3$ configuration. Here, we investigate the electronic and magnetic properties of SrRu$_2$O$_6$ using density functional theory (DFT) combined with dynamical mean field theory (DMFT). We find that the strong hybridization between Ru $d$ and O $p$ states results in a Ru valence that is closer to $+4$, leading to the small ordered moment, consistent with a DFT prediction. While the agreement with DFT might indicate that SrRu$_2$O$_6$ is in the weak coupling regime, our DMFT studies provide evidence from the mass enhancement and local moment formation that indicate correlation effects play a significant role. The local moment per Ru site is about a factor 2 larger than the ordered moment at low temperatures and remains finite in the whole temperature range investigated. Our theoretical N{\\'e}el temperature $\\sim 700$~K is in reasonable agreement with experimental observations. Due to a small lattice distortion, the degenerate $t_{2g}$ manifold is split and the quasiparticle weight is renormalized significantly in the $a_{1g}$ state, while correlation effects in $e_g'$ states are about a factor of 2--3 weaker. SrRu$_2$O$_6$ is a unique system in which localized and itinerant electrons coexist with the proximity to an orbitally-selective Mott transition within the $t_{2g}$ sector.

  5. Inter-taxa differences in root uptake of {sup 103/106}Ru by plants

    Energy Technology Data Exchange (ETDEWEB)

    Willey, N.J. [Centre for Research in Plant Science, Faculty of Applied Sciences, University of the West of England, Frenchay, Bristol BS16 1QY (United Kingdom)]. E-mail: neil.willey@uwe.ac.uk; Fawcett, K. [Centre for Research in Plant Science, Faculty of Applied Sciences, University of the West of England, Frenchay, Bristol BS16 1QY (United Kingdom)

    2006-07-01

    Ruthenium-106 is of potential radioecological importance but soil-to-plant Transfer Factors for it are available only for few plant species. A Residual Maximum Likelihood (REML) procedure was used to construct a database of relative {sup 103/106}Ru concentrations in 114 species of flowering plants including 106 species from experiments and 12 species from the literature (with 4 species in both). An Analysis of Variance (ANOVA), coded using a recent phylogeny for flowering plants, was used to identify a significant phylogenetic effect on relative mean {sup 103/106}Ru concentrations in flowering plants. There were differences of 2465-fold in the concentration to which plant species took up {sup 103/106}Ru. Thirty-nine percent of the variance in inter-species differences could be ascribed to the taxonomic level of Order or above. Plants in the Orders Geraniales and Asterales had notably high uptake of {sup 103/106}Ru compared to other plant groups. Plants on the Commelinoid monocot clades, and especially the Poaceae, had notably low uptake of {sup 103/106}Ru. These data demonstrate that plant species are not independent units for {sup 103/106}Ru concentrations but are linked through phylogeny. It is concluded that models of soil-to-plant transfer of {sup 103/106}Ru should assume that; neither soil variables alone affect transfer nor plant species are independent units, and taking account of plant phylogeny might aid predictions of soil-to-plant transfer of {sup 103/106}Ru, especially for species for which Transfer Factors are not available.

  6. Anchoring hydrous RuO{sub 2} on graphene sheets for high-performance electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zhong-Shuai; Ren, Wencai; Zhao, Jinping; Zhou, Guangmin; Li, Feng; Cheng, Hui-Ming [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang (China); Wang, Da-Wei [ARC Centre of Excellence for Functional Nanomaterials, AIBN, University of Queensland, Brisbane (Australia)

    2010-10-22

    Hydrous ruthenium oxide (RuO{sub 2})/graphene sheet composites (ROGSCs) with different loadings of Ru are prepared by combining sol-gel and low-temperature annealing processes. The graphene sheets (GSs) are well-separated by fine RuO{sub 2} particles (5-20 nm) and, simultaneously, the RuO{sub 2} particles are anchored by the richly oxygen-containing functional groups of reduced, chemically exfoliated GSs onto their surface. Benefits from the combined advantages of GSs and RuO{sub 2} in such a unique structure are that the ROGSC-based supercapacitors exhibit high specific capacitance ({proportional_to}570 F g{sup -1} for 38.3 wt% Ru loading), enhanced rate capability, excellent electrochemical stability ({proportional_to}97.9% retention after 1000 cycles), and high energy density (20.1 Wh kg{sup -1}) at low operation rate (100 mA g{sup -1}) or high power density (10000 W kg{sup -1}) at a reasonable energy density (4.3 Wh kg{sup -1}). Interestingly, the total specific capacitance of ROGSCs is higher than the sum of specific capacitances of pure GSs and pure RuO{sub 2} in their relative ratios, which is indicative of a positive synergistic effect of GSs and RuO{sub 2} on the improvement of electrochemical performance. These findings demonstrate the importance and great potential of graphene-based composites in the development of high-performance energy-storage systems. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Characterization of an innovative method for RuO2 deposition using Electron Microscopy

    DEFF Research Database (Denmark)

    Cavalca, Filippo

    Many photocatalysts work better or exclusively when a suitable cocatalyst, such as RuO2, is deposited on their surface. An innovative method of RuO2 deposition has been found to improve the performance of photocatalysts such as (Ga1-xZnx)(N1-xOx), WO3, SrTiO3 and TiO2. Here we use high angle annu...

  8. H2-splitting on Pt/Ru alloys supported on sputtered HOPG

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Dahl, Søren; Chorkendorff, Ib

    2011-01-01

    that alloying Pt with Ru improves significantly the resistance toward CO poisoning with respect to pure Pt, and the resistance increases with an increasing amount of Ru in the bulk alloys. The faster hydrogen exchange rate with respect to the pure metals and the higher CO tolerance of the alloys are attributed......, and it is attributed to geometrical ensemble effects. © 2011 American Chemical Society....

  9. Promotional effect of upper Ru oxides as methanol tolerant electrocatalyst for the oxygen reduction reaction

    Energy Technology Data Exchange (ETDEWEB)

    Montiel, M.; Hernandez-Fernandez, P.; Ocon, P. [Departamento de Quimica-Fisica Aplicada C-II, Campus UAM, 28049 Madrid (Spain); Fierro, J.L.G.; Rojas, S. [Instituto de Catalisis y Petroleoquimica (CSIC), C/Marie Curie 2, 28049 Madrid (Spain)

    2009-06-15

    The role of Ru on the oxygen reduction reaction in the presence of methanol has been investigated. To this end a series of carbon supported Pt based electrocatalysts containing Ru and Co have been prepared and thoroughly characterized. The catalytic performance on the oxygen reduction reaction (ORR) both in the presence and in the absence of methanol by linear sweep voltammetry on rotating disk electrode has been studied. In spite of its documented ability towards methanol and CO oxidation, when Ru-containing catalysts are subjected to excursions to potentials more positive than 0.8 V vs. NHE they develop a certain tolerance to the presence of methanol. This feature is attributed to the formation of upper oxide Ru species that impede the methanol oxidation reaction to occur under the typical reaction conditions of the oxygen reduction process, i.e. potentials more positive than 0.7 V vs. NHE and oxygen saturated atmospheres. The evolution of Ru species with the applied potential has been investigated by XPS, identifying the presence of upper oxidized Ru phases. (author)

  10. Site dilution in SrRuO3: effects on structural and magnetic properties

    Science.gov (United States)

    Gupta, Renu; Pramanik, A. K.

    2017-03-01

    We have investigated the effect of site dilution with substitution of nonmagnetic element in SrRu1‑x Ti x O3 (x  ⩽  0.7). The nature of ferromagnetic state in SrRuO3 is believed to be of itinerant type with transition temperature {{T}\\text{c}}∼ 162 K. Crystallographically, SrRuO3 has a distorted orthorhombic structure. Substitution of \\text{T}{{\\text{i}}+4} (3d 0) for Ru+4 (4d 4), however, does not introduce significant structural modification due to their matching ionic radii. This substitution, on the other hand, is expected to tune the electronic correlation effect and the d electron density in the system. With Ti substitution, we find that magnetic moment and Curie temperature decreases but T c remains unchanged which has been attributed to opposite tuning of electron correlation effect and density of states within the framework of itinerant ferromagnetism. The estimated critical exponent (β) related to magnetization implies a mean-field type of magnetic nature in SrRuO3. The value of β further increases with x which is understood from the dilution effect of magnetic lattice. The system evolves to exhibit Griffiths phase like behavior above T c which is usually realized in diluted ferromagnet following local moment model of magnetism. Our detail analysis of magnetization data indicates that magnetic state in SrRuO3 has contribution from both itinerant and local moment model of magnetism.

  11. Pattern Growth and Field Emission Characteristics of Flower-Like RuO2 Nanostructures

    Science.gov (United States)

    Lee, Kuei-Yi; Chen, Ching-An; Lian, Huan-Bin; Chen, Yi-Min; Huang, Ying-Sheng; Keiser, Gerd

    2010-10-01

    A flower-like RuO2 nanostructure was selectively synthesized on a Si substrate by metal organic chemical vapor deposition (MOCVD). Bis(ethylcyclopentadienyl) ruthenium(II), Ru[(C2H5)C5H4]2, was shower sprayed onto the Si substrate with oxygen gas. Prior to the growth of the flower-like RuO2 nanostructure, patterns of Al and Fe films were deposited on the Si substrate by photolithography and electron beam (e-beam) evaporation deposition. The synthesized flower-like RuO2 nanostructures were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and micro-Raman spectroscopy. The results indicated that the flower-like nanostructures were RuO2 rutile structures with high crystallinity. For the particular synthesized morphology and design pattern, the current density and long-term stability characteristics of electron field-emission characteristics demonstrated that the flower-like RuO2 nanostructure has the potential to be used in a practical field-emission display.

  12. Interfacial electron transfer dynamics of ru(II)-polypy6ridine sensitized TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Jakubikova, Elena [Los Alamos National Laboratory; Martin, Richard L [Los Alamos National Laboratory; Batista, Enrique R [Los Alamos National Laboratory; Snoeberger, Robert C [YALE UNIV.; Batista, Victor S [YALE UNIV.

    2009-01-01

    Quantum dynamics simulations combined with density functional theory calculations are applied to study interfacial electron transfer (IET) from pyridine-4-phosphonic acid, [Ru(tpy)(tpy(PO{sub 3}H{sub 2}))]{sup 2+} and [Ru(tpy)(bpy)(H{sub 2}O)-Ru(tpy)(tpy(PO{sub 3}H{sub 2}))]{sup 4+} into the (101) surface of anatase TiO{sub 2}. IET rate from pyridine-4-phosphonic acid attached to the nanoparticle in bidentate mode ({tau} {approx} 100 fs) is an order of magnitude faster than the IET rate of the adsorbate attached in the monodentate mode ({tau} {approx} 1 ps). Upon excitation with visible light, [Ru(tpy)(tpy(PO{sub 3}H{sub 2}))]{sup 2+} attached to TiO{sub 2} in bidentate binding mode will undergo IET with the rate of {approx} 1-10 ps, which is competitive with the excited state decay into the ground state. The probability of electron injection from [Ru(tpy)(bpy)(H{sub 2}O)-Ru(tpy)(tpy(PO{sub 3}H{sub 2}))]{sup 4+} is rather low, as the excitation with visible light localizes the excited electron in the tpy-tpy bridge, which does not have favorable coupling with the TiO{sub 2} nanoparticle. The results are relevant to better understanding of the adsorbate features important for promoting efficient interfacial electron transfer into the semiconductor.

  13. Novel Poly-Dopamine Adhesive for a Halloysite Nanotube-Ru(bpy)32+ Electrochemiluminescent Sensor

    Science.gov (United States)

    Xing, Bo; Yin, Xue-Bo

    2009-01-01

    Herein, for the first time, the electrochemiluminescent sensor based on Ru(bpy)32+-modified electrode using dopamine as an adhesive was successfully developed. After halloysite nanotube slurry was cast on a glassy carbon electrode and dried, an alkaline dopamine solution was added on the electrode surface. Initially, polydopamine belts with dimensions of tens to hundreds of nanometers formed via oxidization of the dopamine by ambient oxygen. As the incubation time increased, the nanobelts became broader and then united with each other to form a polydopamine film. The halloysite nanotubes were embedded within the polydopamine film. The above electrode was soaked in Ru(bpy)32+ aqueous solution to adsorb Ru(bpy)32+ into the active sites of the halloysite nanotubes via cation-exchange procedure. Through this simple procedure, a Ru(bpy)32+-modified electrode was obtained using only 6.25 µg Ru(bpy)32+, 15.0 µg dopamine, and 9.0 µg halloysite nanotubes. The electrochemistry and electrochemiluminescence (ECL) of the modified electrode was investigated using tripropylamine (TPA) and nitrilotriacetic acid (NTA) as co-reactants. The different ECL behaviors of the modified electrode using NTA and TPA as well as the contact angle measurements reflected the hydrophilic character of the electrode. The results indicate that halloysite nanotubes have a high loading capacity for Ru(bpy)32+ and that dopamine is suitable for the preparation of modified electrodes. PMID:19649294

  14. Co oxidation on spontaneous Pt-Ru deposits on composite polymeric electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Bavio, M.A.; Kessler, T. [Departamento de Ingenieria Quimica, Facultad de Ingenieria, Universidad Nacional del Centro de la Provincia de Buenos Aires, Av. del Valle 5737, B7400JWI, Olavarria (Argentina); Castro Luna, A.M. [Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas, INIFTA, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Diagonal 113 y 64, 1900, La Plata (Argentina)

    2010-06-15

    Composite polyaniline electrodes containing carbon nanotubes incorporated in the film and spontaneous Pt-Ru deposits as catalytic material for CO oxidation are reported. PANI films were electrosynthesized from a monomer acid solution with the addition of carbon nanotubes. Then, Pt-Ru deposits were obtained by immersing the polymeric film in H{sub 2}PtCl{sub 6} and/or RuCl{sub 3} in HCl. Three series of deposits were prepared by either immersion in a solution containing both metallic ions during a fixed time or successive immersion in different solutions containing only one of the metallic ions during half of the established time and varying the sequence as follows: (i) first in H{sub 2}PtCl{sub 6} and then in RuCl{sub 3} or (ii) first in RuCl{sub 3} and then in H{sub 2}PtCl{sub 6}. Adsorbed CO oxidation was studied by cyclic voltammetry in H{sub 2}SO{sub 4} solution. The electrodes were characterized through SEM and EDX. The different ways to obtain spontaneous Pt-Ru deposits are analyzed and their influence on CO oxidation is discussed. (author)

  15. Research on atomic states, physical properties and catalytic performance of Ru metal

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Using the one-atom theory (OA) of pure metals, the atomic states of Ru metal with hcp structure, fcc structure, bcc structure and liquid state were determined as fol- lows: [Kr](4dn)3.78(4dc)2.22(5sc)1.77(5sf)0.23,Ψa(fcc-Ru)=[Kr](4dn)3.70(4dc)2.44 (5sc)1.42(5sf)0.44, Ψ a(bcc-Ru)=[Kr](4dn)4.00(4dc)2.22(5sc)1.56(5sf)0.22, Ψ a(L-Ru)=[Kr](4dn)4.00(4dc)2.00(5sc)1.52 (5sf)0.48. The potential curve and physical properties as a function of temperature for hcp-Ru such as lattice constant, cohesive energy, linear thermal expansion coeffi- cient, specific heat and Gibbs energy and so on were calculated quantitatively. The theoretical results are in excellent agreement with experimental value. The rela- tionship between the atomic states and catalytic performance was explained qualitatively and these supplied the designation of Ru metal and relative materials with theoretical instruction and complete data.

  16. Electrochemical activation of nanostructured carbon-supported PtRuMo electrocatalyst for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Huerta, M.V., E-mail: mmartinez@icp.csic.e [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Tsiouvaras, N.; Pena, M.A.; Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica, CSIC, Marie Curie 2, 28049 Madrid (Spain); Rodriguez, J.L.; Pastor, E. [Departamento de Quimica Fisica, Universidad de La Laguna, Astrofisico Francisco Sanchez s/n, 38071 Tenerife (Spain)

    2010-11-01

    The factors controlling the behavior and the stability of electrocatalysts based on Pt, Ru and Mo nanoparticles during exhaustive electrochemical treatment are examined. Along this treatment, it has been observed that in the case of ternary catalysts there are pronounced changes in the structure of their surface resulting in electrode activation for methanol and CO electrooxidation, whereas the activity of binary PtRu/C and PtMo/C catalysts decreases. Therefore, the role of both Ru and Mo is crucial for the electrochemical activation of the catalyst, though metal losses do occur during electrochemical process. For the first time a detailed study of this phenomenon is presented, including characterization by HRTEM, TXRF, XRD, electrochemical measurements and in situ Fourier transform infrared spectroscopy (FTIR). In order to get a deeper insight into the surface structure, chemical state, and stability of the electrocatalyst under reaction conditions, a combination of cyclic voltammetry, chronoamperometry and X-ray photoelectron spectroscopy (XPS) has been used. By comparing bulk and surface composition, our results point out to the key role of the geometric effect enhanced by previous reduction of the nanoparticles. At the end of the electrochemical treatment, Mo-PtRu/C catalysts surface was restructured with substantial enrichment in Pt and a less pronounced Mo surface enrichment, while Ru is incorporated into the Pt-Mo overlayer. These results underline the possibility of further optimization of the surface structure and composition producing PtRuMo nanoparticles with high methanol and CO oxidation activity.

  17. Enhanced thermal stability of RuO2/polyimide interface for flexible device applications

    Science.gov (United States)

    Music, Denis; Schmidt, Paul; Chang, Keke

    2017-09-01

    We have studied the thermal stability of RuO2/polyimide (Kapton) interface using experimental and theoretical methods. Based on calorimetric and spectroscopic analyses, this inorganic–organic system does not exhibit any enthalpic peaks as well as all bonds in RuO2 and Kapton are preserved up to 500 °C. In addition, large-scale density functional theory based molecular dynamics, carried out in the same temperature range, validates the electronic structure and points out that numerous Ru–C and a few Ru–O covalent/ionic bonds form across the RuO2/Kapton interface. This indicates strong adhesion, but there is no evidence of Kapton degradation upon thermal excitation. Furthermore, RuO2 does not exhibit any interfacial bonds with N and H in Kapton, providing additional evidence for the thermal stability notion. It is suggested that the RuO2/Kapton interface is stable due to aromatic architecture of Kapton. This enhanced thermal stability renders Kapton an appropriate polymeric substrate for RuO2 containing systems in various applications, especially for flexible microelectronic and energy devices.

  18. Orientation-Dependent Oxygen Evolution on RuO 2 without Lattice Exchange

    Energy Technology Data Exchange (ETDEWEB)

    Stoerzinger, Kelsey A.; Diaz-Morales, Oscar; Kolb, Manuel; Rao, Reshma R.; Frydendal, Rasmus; Qiao, Liang; Wang, Xiao Renshaw; Halck, Niels Bendtsen; Rossmeisl, Jan; Hansen, Heine A.; Vegge, Tejs; Stephens, Ifan E. L.; Koper, Marc T. M.; Shao-Horn, Yang

    2017-03-15

    RuO2 catalysts exhibit record activities towards the oxygen evolution reaction (OER), which is crucial to enable efficient and sustainable energy storage. Here we examine the RuO2 OER kinetics on rutile (110), (100), (101), and (111) orientations, finding (100) the most active. We assess the potential involvement of lattice oxygen in the OER mechanism with online 3 electrochemical mass spectrometry, which showed no evidence of oxygen exchange on these oriented facets in acidic or basic electrolytes. Similar results were obtained for polyoriented RuO2 films and particles, in contrast to previous work, suggesting lattice oxygen is not exchanged in catalyzing OER on crystalline RuO2 surfaces. This hypothesis is supported by the correlation of activity with the number of active Ru-sites calculated by DFT, where more active facets bind oxygen more weakly. This new understanding of the active sites provides a design strategy to enhance the OER activity of RuO2 nanoparticles by facet engineering.

  19. Novel poly-dopamine adhesive for a halloysite nanotube-Ru(bpy(32+ electrochemiluminescent sensor.

    Directory of Open Access Journals (Sweden)

    Bo Xing

    Full Text Available Herein, for the first time, the electrochemiluminescent sensor based on Ru(bpy(3 (2+-modified electrode using dopamine as an adhesive was successfully developed. After halloysite nanotube slurry was cast on a glassy carbon electrode and dried, an alkaline dopamine solution was added on the electrode surface. Initially, polydopamine belts with dimensions of tens to hundreds of nanometers formed via oxidization of the dopamine by ambient oxygen. As the incubation time increased, the nanobelts became broader and then united with each other to form a polydopamine film. The halloysite nanotubes were embedded within the polydopamine film. The above electrode was soaked in Ru(bpy(3 (2+ aqueous solution to adsorb Ru(bpy(3 (2+ into the active sites of the halloysite nanotubes via cation-exchange procedure. Through this simple procedure, a Ru(bpy(3 (2+-modified electrode was obtained using only 6.25 microg Ru(bpy(3 (2+, 15.0 microg dopamine, and 9.0 microg halloysite nanotubes. The electrochemistry and electrochemiluminescence (ECL of the modified electrode was investigated using tripropylamine (TPA and nitrilotriacetic acid (NTA as co-reactants. The different ECL behaviors of the modified electrode using NTA and TPA as well as the contact angle measurements reflected the hydrophilic character of the electrode. The results indicate that halloysite nanotubes have a high loading capacity for Ru(bpy(3 (2+ and that dopamine is suitable for the preparation of modified electrodes.

  20. All Electron ab initio Investigations of the Three Lowest Lying Electronic States of the RuC Molecule

    DEFF Research Database (Denmark)

    Shim, Irene; Gingerich, K. A.

    2000-01-01

    The three lowest-lying electronic states of RuC, (1)Sigma(+), (3)Delta, and (1)Delta, have been investigated by performing all-electron ab initio multi-configuration self-consistent-field (CASSCF) and multi-reference configuration interaction (MRCI) calculations including relativistic corrections....... The electronic ground state is derived as (1)Sigma(+) with the spectroscopic constants r(e) = 1.616 Angstrom and omega(e) = 1085 cm(-1). The lowest-lying excited state, (3)Delta, has r(e) = 1.632 Angstrom, omega(e) = 1063 cm(-1), and T-e = 912 cm(-1). These results are consistent with recent spectroscopic values....... The chemical bonds in all three lowest-lying states are triple bonds composed of one sigma and two pi bonds. (C) 2000 Elsevier Science B.V. All rights reserved....

  1. Selective conversion of polyenes to monoenes by RuCl(3) -catalyzed transfer hydrogenation: the case of cashew nutshell liquid.

    Science.gov (United States)

    Perdriau, Sébastien; Harder, Sjoerd; Heeres, Hero J; de Vries, Johannes G

    2012-12-01

    Cardanol, a constituent of cashew nutshell liquid (CNSL), was subjected to transfer hydrogenation catalyzed by RuCl(3) using isopropanol as a reductant. The side chain of cardanol, which is a mixture of a triene, a diene, and a monoene, was selectively reduced to the monoene. Surprisingly, it is the C8-C9 double bond that is retained with high selectivity. A similar transfer hydrogenation of linoleic acid derivatives succeeded only if the substrate contained an aromatic ring, such as a benzyl ester. TEM and a negative mercury test showed that the catalyst was homogeneous. By using ESI-MS, ruthenium complexes were identified that contained one, two, or even three molecules of substrate, most likely as allyl complexes. The interaction between ruthenium and the aromatic ring determines selectivity in the hydrogenation reaction.

  2. Synthesis of the monooxoruthenium(V) complexes containing the amino polycarboxylic acid ligands EDTA and PDTA and their reactivities in the oxidation of organic substrates. X-ray crystal structures of K[Ru[sup III](EDTA-H)Cl][center dot]2H[sub 2]O and K[Ru[sup III](PDTA-H)Cl][center dot]0. 5H[sub 2]O

    Energy Technology Data Exchange (ETDEWEB)

    Khan, M.M.T.; Chatterjee, D.; Merchant, R.R.; Paul, P.; Abdi, S.H.R.; Srinivas, D.; Siddiqui, M.R.H.; Moiz, M.A.; Bhadbhade, M.M.; Venkatasubramanian, K. (Central Salt and Marine Chemicals Research Institute, Bhavnagar (India))

    1992-06-24

    The syntheses and characterization of K[Ru[sup V][double bond]O(EDTA)] (3) and K[Ru[sup V][double bond]O(PDTA)] (4) are described. The kinetics of the formation of 3 and 4 by the interaction of the corresponding chloro complexes K[Ru[sup III](EDTA-H)Cl] (1) and K[Ru[sup III](PDTA-H)Cl] (2) with the oxygen atom donor NaOCl was investigated in the temperature range 30-50C. The activation parameters of the oxygenation reaction of 1 and 2 to 3 and 4, respectively, are consistent with an associatively activated process. The O atom transfer reaction from 3 and 4 to the unsaturated and saturated hydrocarbons were studied spectrophotometrically in the temperature range 30-50C by following the disappearance of the characteristic oxo peak of the complexes at 393 nm and by product analysis. The activation parameters for the oxidation of the substrates corresponding to the rate-determining oxygen atom transfer step were determined, and a suitable mechanism was proposed. The crystal and molecular structures of the precursor complexes 1 and 2 were determined using single-crystal X-ray diffraction technique.

  3. Structure refinement and magnetic properties of Ce{sub 2}RuAl{sub 3} and a group-subgroup scheme for Ce{sub 5}Ru{sub 3}Al{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Trinath; Hoffmann, Rolf-Dieter; Schwickert, Christian; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2011-08-15

    The hexagonal Laves phase Ce{sub 2}RuAl{sub 3} ({identical_to} CeRu{sub 0.5}Al{sub 1.5}) was synthesized by high-frequence-melting of the elements in a sealed tantalum tube and subsequent annealing. The structure was refined from single-crystal X-ray diffraction data: MgZn{sub 2} type, P6{sub 3}/mmc, Z = 2, a = 565.38(9), c = 888.3(1) pm, wR2 = 0.0231, 193 F{sup 2} values and 13 parameters. The 2a (0.824 Ru + 0.176 Al) and 6h (0.956 Al + 0.044 Ru) Wyckoff positions show mixed occupancies leading to the composition CeRu{sub 0.48}Al{sub 1.52} for the investigated crystal. The aluminum atoms build up Kagome networks at z = 1/4 and z = 3/4 which are connected to a three-dimensional network by the ruthenium atoms. The cerium atoms fill cavities of coordination number 16 (3 Ru + 9 Al + 4 Ce) within the [RuAl{sub 3}] network. The Ce{sub 2}RuAl{sub 3} sample orders ferromagnetically at T{sub C} = 8.0(1) K. The cerium-rich aluminide Ce{sub 5}Ru{sub 3}Al{sub 2} shows unusually short Ce-Ru distances of 253 and 260 pm for the Ce1 position as a result of intermediate cerium valence. The structural distortions are discussed on the basis of a group-subgroup scheme for Pr{sub 5}Ru{sub 3}Al{sub 2} (space group I2{sub 1}3) and the superstructure variant Ce{sub 5}Ru{sub 3}Al{sub 2} (space group R3). (orig.)

  4. Influence of filled d pi-manifold and L/L' ligands on the structure, basicity, and bond rotations of the octahedral and d(6) amido complexes TpRu(L)(L')(NHPh) (Tp = hydridotris(pyrazolyl)borate; L = L' = PMe(3) or P(OMe)(3), or L = CO and L' = PPh(3)): solid-state structures of [TpRu(PMe(3))(2)(NH(2)Ph)][OTf], [TpRu[P(OMe)(3)](2)(NH(2)Ph)][OTf], and TpRu[P(OMe)(3)](2)(NHPh).

    Science.gov (United States)

    Conner, David; Jayaprakash, K N; Gunnoe, T Brent; Boyle, Paul D

    2002-06-03

    It has been suggested that the reactivity of pi-donating ligands bound to late-transition-metal complexes is heightened due to high d-electron counts. Herein, the synthesis and characterization of the Ru(II) amine and Ru(II) amido complexes [TpRuL(2)(NH(2)Ph)][OTf] (OTf = trifluoromethanesulfonate) and TpRuL(2)(NHPh) (L = PMe(3) or P(OMe)(3)) are presented, including solid-state X-ray diffraction studies of [TpRu(PMe(3))(2)(NH(2)Ph)][OTf], [TpRu[P(OMe)(3)](2)(NH(2)Ph)][OTf], and TpRu[P(OMe)(3)](2)(NHPh). The pK(a)'s of the Ru(II) amine complexes and the previously reported [TpRu(CO)(PPh(3))(NH(2)Ph)](+) have been estimated to be comparable to that of malononitrile in methylene chloride. In addition, the impact of the filled dpi-manifold (i.e., Ru(II) and d(6) octahedral systems) on barriers to rotation of the Ru-NHPh moieties has been studied. For TpRu(PMe(3))(2)(NHPh) and TpRu[P(OMe)(3)](2)(NHPh), evidence for hindered rotation about the amido nitrogen and phenyl ipso carbon has been observed, and the relative N-C and Ru-N bond rotational barriers for the series of three amido complexes are discussed in terms of the pi-conflict.

  5. Insight into the mechanical, thermodynamics and superconductor properties of NbRuB via first-principles calculation.

    Science.gov (United States)

    Tian, Wenyan; Chen, Haichuan

    2016-01-01

    Using the first-principles calculations, the electronic structure, chemical bonding, mechanical, thermodynamics and superconductor properties of NbRuB are investigated. The optimized lattice parameters were in good agreement with the experimental data. The analysis of the density of states and chemical bonding implies that the metallic behavior of NbRuB originates from the Ru and Nb, and the bonding behaviors are a mixture of covalent-ionic bonds. The bulk modulus, shear modulus, Young's modulus, Poisson's ratio and hardness of NbRuB were calculated. The results reveal that the NbRuB is ductility and the Vickers hardness is 15.06 GPa. Moreover, the 3D dependences of reciprocals of Young's modulus is also calculated and discussed, showing strong anisotropic character for NbRuB. Finally, the Debye temperature and superconducting transition temperature are obtained.

  6. High-Performance Ru1 /CeO2 Single-Atom Catalyst for CO Oxidation: A Computational Exploration.

    Science.gov (United States)

    Li, Fengyu; Li, Lei; Liu, Xinying; Zeng, Xiao Cheng; Chen, Zhongfang

    2016-10-18

    By means of density functional theory computations, we examine the stability and CO oxidation activity of single Ru on CeO2 (111), TiO2 (110) and Al2 O3 (001) surfaces. The heterogeneous system Ru1 /CeO2 has very high stability, as indicated by the strong binding energies and high diffusion barriers of a single Ru atom on the ceria support, while the Ru atom is rather mobile on TiO2 (110) and Al2 O3 (001) surfaces and tends to form clusters, excluding these systems from having a high efficiency per Ru atom. The Ru1 /CeO2 exhibits good catalytic activity for CO oxidation via the Langmuir-Hinshelwood mechanism, thus is a promising single-atom catalyst.

  7. Bioleaching of Zn, Ni and Fe from contaminated sediments of water reservoir Ružín I with using heterotrophic bacterial strains

    Directory of Open Access Journals (Sweden)

    Katarína Jablonovská

    2012-12-01

    Full Text Available This study investigates the bioleaching of the zinc polluted sediment from water reservoir Ružín I using heterotrophic bacterialstrains ubiquitous in sediment environment. The effect of bacterial activity, pH, iron solubilization and precipitation and bioleachingmedium were evaluated. The pH value controls the bacterial activity during the leaching process. Addition of glucose to the bioleachingmedium accelerated the bioleaching rate. The results indicates, that the leachibility of zinc depend on the geochemical formsand surface interaction between metal and sediment fraction. Sequential chemical extraction confirm, that Zn was predominantly boundto the iron-manganese oxides.

  8. Interference removals on Pd, Ru and Au with ICP-QQQ-MS in PGE RM

    Science.gov (United States)

    Nadeem Hussain Bokhari, Syed; Meisel, Thomas; Walkner, Christoph

    2015-04-01

    Gold and platinum group elements (PGE) are essential industrial precious metals with high world demand due to their unique properties. Struggle for natural exploration of PGE is on great pace and recycling from industrial wastes, electronics and catalytic convertor is on the rise for PGE supply chain. Along with these developments it is becoming more challenging for analytical chemists to determine gold and PGE out of complex matrix which causes severe interferences. The current state of art is online analysis coupled with chromatographic separation of interferences. The ICP-QQQ-MS Agilent 8800 has the capability of using multi tunes and mass shifts. We aim to remove interferences on Pd+ (for direct and isotope dilution analysis) Au+ and Ru+ in lieu of chemical separations. YO+, SrOH+, ZnAr+, NiAr+, ZrO+, CuAr+, MoO+ , Ru+and Cd+ are expected interferences on Pd+ while Au+ is interfered by TaO+, HfOH+, GdAr+ and 102Ru+ ,104Ru+ by 102Pd+ ,104Pd+ etc. Initial test were performed on pure solutions of 1mg/l (interfering elements): 1 ng/l (Pd, Ru & Au) respectively. The outcomes of initial tests were applied on PGE reference material (RM) WMG-1 and SARM-7 (digested with Na2O2 sintering). The results obtained show that YO+, SrOH+ interfere (104Pd,105Pd), 104 Ru+ on (104Pd), ZnAr+ has slight interference on (104Pd and106Pd), ZrO+, NiAr+, CuAr+ interferences are negligible, MoO+ has severe interference on (108Pd, 110Pd) and that Cd+ has severe isobaric interference on (106Pd,108Pd, 110Pd). These interference have been removed by formation of Pd(NH3)3+complex. The TaO+, HfOH+ and GdAr+ interferences on Au+ are best removed by formation of Au(NH3)+ and Au(NH3)2+ complexes. 102Pd+,104Pd+interference on 102Ru+ ,104Ru+ can be removed by formation of Ru(NH3)4+ and RuO+ compounds. The results obtained comply with certified values of RM. The developed method is being tested on low concentration PGE reference materials. References: Sugiyama, N. " Removal of complex spectral

  9. Pt promotion and spill-over processes during deposition and desorption of upd-H(ad) and OH(ad) on Pt(x)Ru(1-x)/Ru(0001) surface alloys.

    Science.gov (United States)

    Hoster, Harry E; Janik, Michael J; Neurock, Matthew; Behm, R Jürgen

    2010-09-21

    The electrochemical adsorption of underpotential deposited hydrogen (upd-H(ad)) and OH(ad) on structurally well-defined Pt(x)Ru(1-x)/Ru(0001) surface alloys was investigated by cyclic voltammetry and density functional theory (DFT) calculations. The adsorption energies of both upd-H(ad) and OH(ad) decrease with increasing Pt content in the adsorption ensemble, shifting the onset of upd-H(ad) and OH(ad) formation to increasingly cathodic and anodic potentials, respectively. For bare Ru(0001) and for Ru(3) sites in the surface alloy, the stability regions of these two species overlap or almost overlap, respectively. Similar to previous findings for upd-H(ad) adsorption/desorption on partly Pt monolayer island covered Ru(0001) surfaces (J. Phys. Chem. B 2004, 108, 14780), we find a sharp peak at approximately 100 mV vs. RHE in each scan direction, which is attributed to a Pt catalyzed OH(ad) upd-H(ad) replacement on Ru(3) sites, via adsorption on Pt rich sites and spill-over to Ru(3) sites. The decrease of the integrated charge in these peaks with the third power of the Ru surface concentration, which for a random distribution of surface atoms reflects the availability of Ru(3) sites, supports the above assignment.

  10. Origins of enantioselectivity in asymmetric ketone hydrogenation catalyzed by a RuH2(binap)(cydn) complex: insights from a computational study.

    Science.gov (United States)

    Feng, Ran; Xiao, Ang; Zhang, Xin; Tang, Yanhui; Lei, Ming

    2013-02-14

    In this paper, the origins of enantioselectivity in asymmetric ketone hydrogenation catalyzed by RuH(2)(binap)(cydn) (cydn = trans-1,2-diaminocyclohexane) were discussed. Fifteen substrates involving aromatic, heteroaromatic, olefinic and dialkyl prochiral ketones were used to probe the catalytic mechanism and find an effective way to predict the chirality of the products. The calculated results demonstrate that the hydrogen transfer (HT) step from the Ru complex to the ketone substrate is the chirality-determining step in the H(2)-hydrogenation of ketones. The hydrogenation of aromatic-alkyl ketones can give higher enantiomeric excess (ee) values than that of dialkyl ketones. An interesting intermediate (denoted as ) could be formed if there is an α-hydrogen for R/R' groups of the ketone due to the H(2)-H(α) interaction. Two substituent groups of the ketone could rotate around the C=O axis in two directions, clockwise or counter-clockwise. This rotation, with the big or conjugative substituent group away from/toward the closer binap ligand of the Ru catalyst, will form favorable/unfavorable chiral products with an Re-/Si- intermediate structure. On the contrary, if there is no such α-hydrogen in any substituent group of the ketone, ABS and another intermediate (denoted as INT) would not exist. This study indicates that the conjugative effect of the substituent groups of the ketone play an important role in differentiating the R/R' groups of the ketone, while steric and electrostatic effects contribute to a minor extent. Furthermore, the disparity of the R and R' groups of the ketone is of importance in the enantioselectivity and the favorable chiral alcohol is formed when the structure of the conjugative/big substituent group is away from the closer binap ligand of the RuH(2)(binap)(cydn) catalyst. According to the three factors of the substituent group and the fourth quadrant theory, the enantioselectivity of 91 prochiral ketones catalyzed by a series of Ru

  11. Synthesis and Evaluation of In Vitro DNA/Protein Binding Affinity, Antimicrobial, Antioxidant and Antitumor Activity of Mononuclear Ru(II) Mixed Polypyridyl Complexes.

    Science.gov (United States)

    Putta, Venkat Reddy; Chintakuntla, Nagamani; Mallepally, Rajender Reddy; Avudoddi, Srishailam; K, Nagasuryaprasad; Nancherla, Deepika; V V N, Yaswanth; R S, Prakasham; Surya, Satyanarayana Singh; Sirasani, Satyanarayana

    2016-01-01

    The four novel Ru(II) complexes [Ru(phen)2MAFIP](2+) (1) [MAFIP = 2-(5-(methylacetate)furan-2-yl)-1 H-imidazo[4,5-f] [1, 10]phenanthroline, phen = 1,10-Phenanthroline], [Ru(bpy)2MAFIP](2+) (2) (bpy = 2,2'-bipyridine) and [Ru(dmb)2MAFIP](2+) (3) (dmb = 4,4'-dimethyl-2,2'-bipyridine) and [Ru(hdpa)2MAFIP](2+) (4) (hdpa = 2,2-dipyridylamine) have been synthesized and fully characterized via elemental analysis, NMR spectroscopy, EI-MS and FT-IR spectroscopy. In addition, the DNA-binding behaviors of the complexes 1-4 with calf thymus DNA were investigated by UV-Vis absorption, fluorescence studies and viscosity measurement. The DNA-binding experiments showed that the complexes 1-4 interact with CT-DNA through an intercalative mode. BSA protein binding affinity of synthesized complexes was determined by UV/Vis absorption and fluorescence emission titrations. The binding affinity of ruthenium complexes was supported by molecular docking. The photoactivated cleavage of plasmid pBR322 DNA by ruthenium complexes 1-4 was investigated. All the synthesized compounds were tested for antimicrobial activity by using three Gram-negative (Escherichia coli, Salmonella typhi and Pseudomonas aeruginosa) and three Gram-positive (Micrococcus luteus, Bacillus subtilis and Bacillus megaterium) organisms, these results indicated that complex 3 was more activity compared to other complexes against all tested microbial strains while moderate antimicrobial activity profile was noticed for complex 4. The antioxidant activity experiments show that the complexes exhibit moderate antioxidant activity. The cytotoxicity of synthesized complexes on HeLa cell lines has been examined by MTT assay. The apoptosis assay was carried out with Acridine Orange (AO) staining methods and the results indicate that complexes can induce the apoptosis of HeLa cells. The cell cycle arrest investigated by flow cytometry and these results indicate that complexes 1-4 induce the cell cycle arrest at G0/G1

  12. Induction of Cytotoxicity in Pyridine Analogues of the Anti-metastatic Ru(III) Complex NAMI-A by Ferrocene Functionalization.

    Science.gov (United States)

    Mu, Changhua; Chang, Stephanie W; Prosser, Kathleen E; Leung, Ada W Y; Santacruz, Stephanie; Jang, Thalia; Thompson, John R; Yapp, Donald T T; Warren, Jeffrey J; Bally, Marcel B; Beischlag, Timothy V; Walsby, Charles J

    2016-01-04

    A series of novel ferrocene (Fc) functionalized Ru(III) complexes was synthesized and characterized. These compounds are derivatives of the anti-metastatic Ru(III) complex imidazolium [trans-RuCl4(1H-imidazole) (DMSO-S)] (NAMI-A) and are derived from its pyridine analogue (NAMI-Pyr), with direct coupling of Fc to pyridine at the 4 or 3 positions, or at the 4 position via a two-carbon linker, which is either unsaturated (vinyl) or saturated (ethyl). Electron paramagnetic resonance (EPR) and UV-vis spectroscopic studies of the ligand exchange processes of the compounds in phosphate buffered saline (PBS) report similar solution behavior to NAMI-Pyr. However, the complex with Fc substitution at the 3 position of the coordinated pyridine shows greater solution stability, through resistance to the formation of oligomeric species. Further EPR studies of the complexes with human serum albumin (hsA) indicate that the Fc groups enhance noncoordinate interactions with the protein and help to inhibit the formation of protein-coordinated species, suggesting the potential for enhanced bioavailability. Cyclic voltammetry measurements demonstrate that the Fc groups modestly reduce the reduction potential of the Ru(III) center as compared to NAMI-Pyr, while the reduction potentials of the Fc moieties of the four compounds vary by 217 mV, with the longer linkers giving significantly lower values of E1/2. EPR spectra of the compounds with 2-carbon linkers show the formation of a high-spin Fe(III) species (S = 5/2) in PBS with a distinctive signal at g = 4.3, demonstrating oxidation of the Fe(II) ferrocene center and likely reflecting degradation products. Density functional theory calculations and paramagnetic (1)H NMR describe delocalization of spin density onto the ligands and indicate that the vinyl linker could be a potential pathway for electron transfer between the Ru and Fe centers. In the case of the ethyl linker, electron transfer is suggested to occur via an indirect

  13. Oxidation and growth of Mg thin films on Ru(001)

    Science.gov (United States)

    Huang, H. H.; Jiang, X.; Siew, H. L.; Chin, W. S.; Sim, W. S.; Xu, G. Q.

    1999-08-01

    The oxidation and growth of ultra-thin Mg films on a Ru(001) substrate have been studied using X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS) in the temperature range of 300-1500 K. Our results suggest that the growth of Mg thin films follows a layer-by-layer mode. Upon oxygen adsorption at 300 K, two O 1s peaks were detected on the Mg film. The peak at 532.2-532.6 eV could be attributed to either dioxygen or partially reduced species (O δ-, δfilm to 800 K causes the conversion of the dioxygen or partially reduced species to the oxide state. Thermal desorption peaks of MgO were directly detected at 1000-1127 and 1350-1380 K, respectively. However, initial evaporation of Mg atoms onto an oxygen pre-adsorbed surface yields a fully oxidized MgO. Further Mg deposition results in the formation of a partially oxidized film with the observation of an O 1s peak at 532.2 eV.

  14. Quantum effects in the diffusion of hydrogen on Ru(0001)

    CERN Document Server

    McIntosh, Eliza M; Ellis, John; Michaelides, Angelos; Allison, William

    2014-01-01

    An understanding of hydrogen diffusion on metal surfaces is important, not just for its role in heterogeneous catalysis and hydrogen fuel cell technology, but also because it provides model systems where tunneling can be studied under well-defined conditions. Here we report helium spin-echo measurements of the atomic-scale motion of hydrogen on the Ru(0001) surface between 75 and 250 K. Quantum effects are evident at temperatures as high as 200 K, while below 120 K we observe a tunneling-dominated temperature independent jump rate of 1.9$\\times$10$^9$ s$^{-1}$, many orders of magnitude faster than previously seen. Quantum transition state theory calculations based on ab initio path-integral simulations reproduce the temperature dependence of the rate at higher temperatures and predict a crossover to tunneling-dominated diffusion at low temperatures, although the tunneling rate is under-estimated, highlighting the need for future experimental and theoretical studies of hydrogen diffusion on well-defined surfac...

  15. Vibrating Reed Study of CeRu_2

    Science.gov (United States)

    Olinger, A., Jr.; Childers, J. G.; Zhang, Junqing; Metlushko, V.; Delong, L. E.

    1996-03-01

    DC magnetization, AC magnetic susceptibility, vibrating reed (VR) and magnetoresistance measurements were performed on CeRux (x 2.0) samples. CeRu2 has been proposed as an unconventional superconductor based on heat capacity data (Sereni et al., 1989). A small interval of reversible, positive DC magnetization just below the upper critical field H_c2 followed by a region of giant magnetic hysteresis (GMH) at lower temperature (Roy, 1992; Yagasaki et al., 1993) suggest the existence of a "Fulde-Farrell" state (Huxley et al., 1993). We find a dip in the VR dissipation 1/Q that implies a peak effect in the critical current density exists at the lower boundary of the GMH region. VR hysteresis extends from this boundary to well below the GMH region, within which a large 1/Q peak is found to exhibit no hysteresis. We infer the magnetic response is drive and frequency dependent nearly everywhere below H_c2. The field dependence of 1/Q implies that a plastically deformed vortex lattice or glass phase exists well below the GMH region. * Funded by NSF Grant #EHR-9108764

  16. Phototriggered sulfoxide isomerization in [Ru(pic)2(dmso)2].

    Science.gov (United States)

    Rachford, Aaron A; Petersen, Jeffrey L; Rack, Jeffrey J

    2007-08-14

    We report the characterization and photochemistry of a simple ruthenium coordination complex containing only picolinate (pic) and dmso, which exhibits a large isomerization quantum yield (Phi(SS-->OO) = 0.50) in various solvents. The picolinate ligands of [Ru(pic)(2)(dmso)(2)] are in a cis arrangement so that the carboxylate oxygen of one pic ligand (O1) is trans to the pyridine of the second picolinate (N2). One dmso ligand (S1) is trans to a pyridine nitrogen (N1), while the second dmso (S2) is trans to a carboxylate oxygen (O3). The cyclic voltammetry, (1)H NMR, IR, and UV-vis spectroscopy data suggest that while both dmso ligands isomerize photochemically, only one dmso ligand isomerizes electrochemically. Isomerization quantum yields for each dmso ligand differ by an order of magnitude (Phi(SS-->SO) = 0.46 and Phi(SO-->OO) = 0.036). In agreement with previous results, the isomerization quantum yield for each dmso is dependent on the ligand that is trans to the dmso.

  17. Infrared vibrational spectroscopy of [Ru(bpy)2(bpm)]2+ and [Ru(bpy)3]2+ in the excited triplet state.

    Science.gov (United States)

    Mukuta, Tatsuhiko; Fukazawa, Naoto; Murata, Kei; Inagaki, Akiko; Akita, Munetaka; Tanaka, Sei'ichi; Koshihara, Shin-ya; Onda, Ken

    2014-03-03

    This work involved a detailed investigation into the infrared vibrational spectra of ruthenium polypyridyl complexes, specifically heteroleptic [Ru(bpy)2(bpm)](2+) (bpy = 2,2'-bipyridine and bpm = 2,2'-bipyrimidine) and homoleptic [Ru(bpy)3](2+), in the excited triplet state. Transient spectra were acquired 500 ps after photoexcitation, corresponding to the vibrational ground state of the excited triplet state, using time-resolved infrared spectroscopy. We assigned the observed bands to specific ligands in [Ru(bpy)2(bpm)](2+) based on the results of deuterium substitution and identified the corresponding normal vibrational modes using quantum-chemical calculations. Through this process, the more complex vibrational bands of [Ru(bpy)3](2+) were assigned to normal vibrational modes. The results are in good agreement with the model in which excited electrons are localized on a single ligand. We also found that the vibrational bands of both complexes associated with the ligands on which electrons are little localized appear at approximately 1317 and 1608 cm(-1). These assignments should allow the study of the reaction dynamics of various photofunctional systems including ruthenium polypyridyl complexes.

  18. Pärnu Vallikääru park = Vallikääru park, Pärnu / Kersti Lootus ; intervjueerinud Margit Mutso

    Index Scriptorium Estoniae

    Lootus, Kersti, 1953-

    2012-01-01

    Pärnu Vallikääru pargi arhitektid Kersti Lootus, Kiur Lootus, Heidi Viilop ja Siim Lootus ning maastikuarhitekt Katri Soonberg (Lootusprojekt) pälvisid EK arhitektuuri sihtkapitali 2011. a. maastikuarhitektuuri preemia nüüdisaegse linnapargi lahenduse eest ajaloolises linnakindlustusvööndis. Metallikunstnik Harvi Varkki

  19. Pärnu Vallikääru park = Vallikääru park, Pärnu / Kersti Lootus ; intervjueerinud Margit Mutso

    Index Scriptorium Estoniae

    Lootus, Kersti, 1953-

    2012-01-01

    Pärnu Vallikääru pargi arhitektid Kersti Lootus, Kiur Lootus, Heidi Viilop ja Siim Lootus ning maastikuarhitekt Katri Soonberg (Lootusprojekt) pälvisid EK arhitektuuri sihtkapitali 2011. a. maastikuarhitektuuri preemia nüüdisaegse linnapargi lahenduse eest ajaloolises linnakindlustusvööndis. Metallikunstnik Harvi Varkki

  20. Synthesis and Electrocatalytic Performance of Multi-Component Nanoporous PtRuCuW Alloy for Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Xiaoting Chen

    2015-06-01

    Full Text Available We have prepared a multi-component nanoporous PtRuCuW (np-PtRuCuW electrocatalyst via a combined chemical dealloying and mechanical alloying process. The X-ray diffraction (XRD, transmission electron microscopy (TEM and electrochemical measurements have been applied to characterize the microstructure and electrocatalytic activities of the np-PtRuCuW. The np-PtRuCuW catalyst has a unique three-dimensional bi-continuous ligament structure and the length scale is 2.0 ± 0.3 nm. The np-PtRuCuW catalyst shows a relatively high level of activity normalized to mass (467.1 mA mgPt−1 and electrochemically active surface area (1.8 mA cm−2 compared to the state-of-the-art commercial PtC and PtRu catalyst at anode. Although the CO stripping peak of np-PtRuCuW 0.47 V (vs. saturated calomel electrode, SCE is more positive than PtRu, there is a 200 mV negative shift compared to PtC (0.67 V vs. SCE. In addition, the half-wave potential and specific activity towards oxygen reduction of np-PtRuCuW are 0.877 V (vs. reversible hydrogen electrode, RHE and 0.26 mA cm−2, indicating a great enhancement towards oxygen reduction than the commercial PtC.

  1. Selective CO methanation over amorphous Ni-Ru-B/ZrO2 catalyst for hydrogen-rich gas purification

    Institute of Scientific and Technical Information of China (English)

    Qihai Liu; Zili Liu; LieWen Liao; Xinfa Dong

    2010-01-01

    Amorphous Ni-Ru-B/ZrO2 catalysts were prepared by chemical reduction method.The effects of Ni-Ru-B loading and Ru/Ni mole ratio on the catalytic performance for selective CO methanation from reformed fuel were studied,and the catalysts were characterized by BET,ICE XRD and TPD.The results showed that Ru strongly affected the catalytic activity and selectivity by increasing the thermal stability of amorphous structure,promoting the dispersion of the catalyst particle,and intensifying the CO adsorption.For the catalysts with Ru/Ni mole ratio under 0.15,the CO methanation conversion and selectivity increased significantly with the increasing Ru/Ni mole ratio.Among all the catalysts investigated,the 30 wt% Ni-Ru-B loading amorphous Ni61Ru9B30/ZrO2 catalyst with 0.15 Ru/Ni mole ratio presented the best catalytic performance,over which higher than 99.9% of CO conversion was obtained in the temperature range of 230℃~250℃,and the CO2 conversion was kept under the level of 0.9%.

  2. Copper-incorporated mono- and di-TeRu5 metal carbonyl complexes: syntheses, structures, and an unusual skeletal arrangement.

    Science.gov (United States)

    Shieh, Minghuey; Miu, Chia-Yeh; Hsing, Kai-Jieah; Jang, Li-Fing; Lin, Chien-Nan

    2015-04-14

    Two sandwich-type Cu3Cl- or Cu2{Te2Ru4(CO)10}-bridging di-TeRu5 clusters, [{TeRu5(CO)14}2Cu3Cl](2-) () and [{TeRu5(CO)14}2Cu2{Te2Ru4(CO)10}](4-) (), were obtained from the reaction of [TeRu5(CO)14](2-) with 1 equiv. of [Cu(MeCN)4][BF4] in CH2Cl2 or THF at 0 °C, respectively, depending on the solvents. The chloride-abstracted was structurally characterized to have two TeRu5 cores that were linked by a Cu3Cl moiety with two Cu-Cu bonds. If the reaction was carried out in a molar ratio of 1 : 2 at 0 or 30 °C in CH2Cl2, the structural isomers [TeRu5(μ-CO)2(CO)12(CuMeCN)2] () and [TeRu5(μ-CO)3(CO)11Cu2(MeCN)2] () were produced, respectively, as the major product. Cluster displayed a TeRu5 core with two adjacent Ru3 triangles each capped by a μ3-Cu(MeCN) fragment, while contained a TeRu5 core with one triangle Ru3 plane capped by a Cu2(MeCN)2 fragment with two Cu atoms covalently bonded. Upon heating, the isomerization of into proceeded to undergo an unusual skeletal arrangement of Cu(MeCN) and migration of CO, with the TeRu5 core remaining intact. An electrochemical study revealed that and each exhibited only one oxidation while cluster had two consecutive oxidations, suggesting significant electronic communication between the two TeRu5 metal cores in via the Cu3 moiety. This work describes the facile synthesis of a series of semiconducting Cux-bridging Te-Ru carbonyl clusters, in which the incorporation of the Cux fragments has significantly influenced their resulting structures, rearrangements, and electronic properties, which was further elucidated by DFT calculations.

  3. Synthesis of PtRu nanoparticles from the hydrosilylation reaction and application as catalyst for direct methanol fuel cell.

    Science.gov (United States)

    Huang, Junchao; Liu, Zhaolin; He, Chaobin; Gan, Leong Ming

    2005-09-08

    Nanosized Pt, PtRu, and Ru particles were prepared by a novel process, the hydrosilylation reaction. The hydrosilylation reaction is an effective method of preparation not only for Pt particles but also for other metal colloids, such as Ru. Vulcan XC-72 was selected as catalyst support for Pt, PtRu, and Ru colloids, and TEM investigations showed nanoscale particles and narrow size distribution for both supported and unsupported metals. All Pt and Pt-rich catalysts showed the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure, whereas the Ru and Ru-rich alloys were more typical of a hexagonal close-packed (hcp) structure. As evidenced by XPS, most Pt and Ru atoms in the nanoparticles were zerovalent, except a trace of oxidation-state metals. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results concluded that some alloy catalysts showed higher catalytic activities and better CO tolerance than the Pt-only catalyst; Pt56Ru44/C have displayed the best electrocatalytic performance among all carbon-supported catalysts.

  4. Microwave-assisted synthesis and characterization of bimetallic PtRu alloy nanoparticles supported on carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Rahsepar, Mansour, E-mail: rahsepar@shirazu.ac.ir [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Zand Boulevard, Shiraz, 7134851154 (Iran, Islamic Republic of); Kim, Hasuck, E-mail: hasuckim@snu.ac.kr [Department of Chemistry, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-747 (Korea, Republic of); Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science & Technology, Daegu, 711-873 (Korea, Republic of)

    2015-11-15

    Multiwalled carbon nanotube (MWCNT) supported PtRu nanoparticles were synthesized by using a microwave-assisted improved impregnation technique. X-ray diffraction, transmission electron microscopy and X-ray photo electron spectroscopy were used to characterize the prepared PtRu/MWCNT nanoparticles. The PtRu nanoparticles with a satisfactory dispersion were formed on the external surface of MWCNTs. The CO stripping experiment was performed to evaluate the poisoning resistance of the prepared PtRu/MWCNT nanoparticles. Results of electrochemical measurements indicate that the prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning. The results of characterization revealed that microwave-assisted improved impregnation technique have a high yield of alloy phase formation and could be effectively used as a simple, quick and efficient technique for preparation of bimetallic PtRu/MWCNT nanoparticles. - Highlights: • Highly dispersed PtRu/MWCNTs were formed without use of any stabilizing agent. • Microwave irradiation enhances the uniform dispersion of the PtRu nanoparticles. • Microwave-assisted improved impregnation have a high yield of alloy phase formation. • The prepared PtRu/MWCNTs shows an enhanced performance toward CO poisoning.

  5. Astrophysical S-Factors and Reaction Rates of Threshold (p, n)-Reactions on 99-102Ru

    Science.gov (United States)

    Skakun, Ye.; Rauscher, T.

    2010-08-01

    Astrophysical S-factors of (p, n) reactions on 99Ru, 100Ru, 101Ru, and 102Ru were derived from the sum of experimental isomeric and ground states cross sections measured in the incident proton energy range of 5-9 MeV. They were compared with Hauser-Feshbach statistical model predictions of the NON-SMOKER code. Good agreement was found in the majority of cases. Reaction rates were derived up to 8.7 GK stellar temperature by combining experiment and theory.

  6. X-ray and Raman spectroscopic studies on Ru substituted LiMn{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kalavathi, S.; Ravindran, T. R.; Sahu, P. Ch. [Condensed Matter Physics Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam -603102 (India); Kalaivani, D., E-mail: kala@igcar.gov.in [Department of Physics, Rajiv Gandhi College of Engineering Technology, Pondicherry-607403 (India)

    2015-06-24

    Phase pure Ru substituted LiMn{sub 2}O{sub 4} charge frustrated spinel compounds have been synthesized. Ru substitution for Mn is possible only up to 7.5%. Powder diffraction measurements confirm sustenance of charge frustrated cubic phase with space group Fd3m upon substitution of Ru for Mn. An increase in lattice parameter has been observed indicating replacement of Mn as Ru{sup 3+} or Ru{sup 4+} rather than Ru{sup 5+}. Raman spectroscopic measurements show that the crystal structure is robust against an increase of laser power and the observed bands show an expected red shift. In the case of Ru substituted LiMn{sub 2}O{sub 4}, the A{sub 1g} symmetric stretching mode, the F{sup (1)}{sub 2g} and the F{sup (2)}{sub 2g} symmetric bending modes identified with the Mn-O octahedra show a red shift up to Ru 0.075 and at higher Ru concentrations, revert back to the frequency corresponding to the pristine LiMn{sub 2}O{sub 4}.

  7. Investigation of the site preference in Mn2RuSn using KKR-CPA-LDA calculation

    Science.gov (United States)

    Yang, Ling; Liu, Bohua; Luo, Hongzhi; Meng, Fanbin; Liu, Heyan; Liu, Enke; Wang, Wenhong; Wu, Guangheng

    2015-05-01

    We investigated the site preference and atomic disorder between the A and C sites in Heusler alloy Mn2RuSn by using the KKR-CPA-LDA method. It is found that, at ground state 0 K, the Hg2CuTi-type (XA) structure is energetically favored, in which one Mn and one Ru occupy the A and C sites, respectively. The ground state energy of Mn2RuSn increases with increasing degree of Mn (A)-Ru (C) atomic disorder. The equilibrium lattice constants also show a similar tendency. The Mn (A)-Ru (C) disorder lower the total spin moment effectively, which is 1.87 μB in the XA structure and only 0.98 μB in the L21B structure. In Mn2RuSn with different degree of Mn (A)-Ru (C) atomic disorder, the total moments are always determined by the antiparallel aligned Mn (A, C) and Mn (B) spin moments. The saturated moment of Mn2RuSn at 5 K is 1.68 μB, which corresponds to ∼11% antisite Mn entering the C site. This Mn (A)-Ru (C) disorder in samples can be related to the contributions from entropy of mixing at elevated temperatures, especially when this sample is quenched from high temperatures.

  8. Supercapacitive Properties of 3D-Arrayed Polyaniline Hollow Nanospheres Encaging RuO2 Nanoparticles.

    Science.gov (United States)

    Kwon, Hyemin; Hong, Dajung; Ryu, Ilhwan; Yim, Sanggyu

    2017-03-01

    A major limitation of polyaniline (PANi) electrodes for supercapacitors is the slow rate of ion transport during redox reactions and the resultant easy saturation of areal capacitance with film thickness. In this study, three-dimensionally (3D)-arrayed PANi nanospheres with highly roughened surface nanomorphology were fabricated to overcome this limitation. A hierarchical nanostructure was obtained by polymerizing aniline monomers on a template of 3D-arrayed polystyrene (PS) nanospheres and appropriate oxidative acid doping. The structure provided dramatically increased surface area and porosity that led to the efficient diffusion of ions. Thus, the specific capacitance (Csp) reached 1570 F g(-1), thereby approaching a theoretical capacitance of PANi. In addition, the retention at a high scan rate of 100 mV s(-1) was 77.6% of the Csp at a scan rate of 10 mV s(-1). Furthermore, 3D-arrayed hollow PANi (H-PANi) nanospheres could be obtained by dissolving the inner PS part of the PS/PANi core/shell nanospheres with tetrahydrofuran. The ruthenium oxide (RuO2) nanoparticles (NPs) were also encaged in the H-PANi nanospheres by embedding RuO2 NPs on the PS nanospheres prior to polymerization of PANi. The combination of the two active electrode materials indicated synergetic effects. The areal capacitance of the RuO2-encaged PANi electrode was significantly larger than that of the RuO2-free PANi electrode and could be controlled by varying the amount of encaged RuO2 nanoparticles. The encagement could also solve the problem of detachment of RuO2 electrodes from the current collector. The effects of the nanostructuring and RuO2 encagement were also quantitatively analyzed by deconvoluting the total capacitance into the surface capacitive and insertion elements.

  9. Synthesis, Characterization, Anticancer, and Antioxidant Studies of Ru(III) Complexes of Monobasic Tridentate Schiff Bases

    Science.gov (United States)

    Ejidike, Ikechukwu P.

    2016-01-01

    Mononuclear Ru(III) complexes of the type [Ru(LL)Cl2(H2O)] (LL = monobasic tridentate Schiff base anion: (1Z)-N′-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)-N-phenylethanimidamide [DAE], 4-[(1E)-N-{2-[(Z)-(4-hydroxy-3-methoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [HME], 4-[(1E)-N-{2-[(Z)-(3,4-dimethoxybenzylidene)amino]ethyl}ethanimidoyl]benzene-1,3-diol [MBE], and N-(2-{(E)-[1-(2,4-dihydroxyphenyl)ethylidene]amino}ethyl)benzenecarboximidoyl chloride [DEE]) were synthesized and characterized using the microanalytical, conductivity measurements, electronic spectra, and FTIR spectroscopy. IR spectral studies confirmed that the ligands act as tridentate chelate coordinating the metal ion through the azomethine nitrogen and phenolic oxygen atom. An octahedral geometry has been proposed for all Ru(III)-Schiff base complexes. In vitro anticancer studies of the synthesized complexes against renal cancer cells (TK-10), melanoma cancer cells (UACC-62), and breast cancer cells (MCF-7) was investigated using the Sulforhodamine B assay. [Ru(DAE)Cl2(H2O)] showed the highest activity with IC50 valves of 3.57 ± 1.09, 6.44 ± 0.38, and 9.06 ± 1.18 μM against MCF-7, UACC-62, and TK-10, respectively, order of activity being TK-10 [Ru(HME)Cl2(H2O)] > [Ru(DAE)Cl2(H2O)] > [Ru(MBE)Cl2(H2O)]. PMID:27597814

  10. Anomalous perovskite PbRuO3 stabilized under high pressure.

    Science.gov (United States)

    Cheng, J-G; Kweon, K E; Zhou, J-S; Alonso, J A; Kong, P-P; Liu, Y; Jin, Changqing; Wu, Junjie; Lin, Jung-Fu; Larregola, S A; Yang, Wenge; Shen, Guoyin; MacDonald, A H; Manthiram, Arumugam; Hwang, G S; Goodenough, John B

    2013-12-10

    Perovskite oxides ABO3 are important materials used as components in electronic devices. The highly compact crystal structure consists of a framework of corner-shared BO6 octahedra enclosing the A-site cations. Because of these structural features, forming a strong bond between A and B cations is highly unlikely and has not been reported in the literature. Here we report a pressure-induced first-order transition in PbRuO3 from a common orthorhombic phase (Pbnm) to an orthorhombic phase (Pbn21) at 32 GPa by using synchrotron X-ray diffraction. This transition has been further verified with resistivity measurements and Raman spectra under high pressure. In contrast to most well-studied perovskites under high pressure, the Pbn21 phase of PbRuO3 stabilized at high pressure is a polar perovskite. More interestingly, the Pbn21 phase has the most distorted octahedra and a shortest Pb-Ru bond length relative to the average Pb-Ru bond length that has ever been reported in a perovskite structure. We have also simulated the behavior of the PbRuO3 perovskite under high pressure by first principles calculations. The calculated critical pressure for the phase transition and evolution of lattice parameters under pressure match the experimental results quantitatively. Our calculations also reveal that the hybridization between a Ru:t2g orbital and an sp hybrid on Pb increases dramatically in the Pbnm phase under pressure. This pressure-induced change destabilizes the Pbnm phase to give a phase transition to the Pbn21 phase where electrons in the overlapping orbitals form bonding and antibonding states along the shortest Ru-Pb direction at P > Pc.

  11. Synthesis, characterization, and electronic structures of a series of two-dimensional trimetallic cluster complexes, Ru3(CO)9(mu-SnPh2)3[Pt(PBu(t)3)]x, x = 0-3.

    Science.gov (United States)

    Adams, Richard D; Captain, Burjor; Hall, Michael B; Trufan, Eszter; Yang, Xinzheng

    2007-10-10

    The triruthenium-tritin cluster complex, Ru3(CO)9(mu-SnPh2)3, 13 was obtained from the reaction of Ru3(CO)12 with Ph3SnH. Compound 13 reacts with Pt(PBut3)2 to yield three new Pt(PBut3) adducts of 13 Ru3(CO)9(mu-SnPh2)3[Pt(PBut3)]x, 14-16 x = 1 - 3 formed by the addition of Pt(PBut3) groups to the Ru-Sn bonds. The new complexes form a novel series of trimetallic complexes having planar arrangements of the metal atoms. The UV-vis absorptions of the four complexes shift progressively to longer wavelengths as the number of platinum atoms is added to the cluster. The electronic structures of these complexes have been investigated in the ground and excited states by density functional theory and time-dependent density functional theory, and this has provided a detailed understanding of the metal-metal bonding and electronic transitions that are responsible for their UV-vis absorption properties. The predicted absorption maximum for the model structures for 13, 14, 15, and 16 at 465, 508, 556, and 585 nm differ only 4-18 nm from the experimental values of 474, 490, 552, and 576 nm. The shift of principal UV-vis absorption can be explained by a lowering of the HOMO-LUMO energy gap due to interactions of the platinum atoms with the HOMO and LUMO of the Ru3Sn3 core.

  12. Electrochemical surface characterization and O2 reduction kinetics of Se surface-modified ru nanoparticle-based RuSe(y)/C catalysts.

    Science.gov (United States)

    Colmenares, L; Jusys, Z; Behm, R J

    2006-12-05

    The electrochemical properties of Se surface-modified Ru/C catalysts (RuSey/C with y = 0 to 1) and their O2 reduction characteristics were determined in model studies under well-defined mass transport conditions, combining quantitative differential electrochemical mass spectrometry and double-disk electrode thin-layer flow-cell measurements. Surface characterization of the catalysts including the quantitative evaluation of the active surface area was performed by electrochemical/mass spectrometric (combined H-upd adsorption, preadsorbed CO monolayer oxidation, Cu-upd adsorption/stripping, and RuOx formation) methods. The suitability of these methods for the determination of the active surface area in the high and low Se coverage regime are discussed, and COad stripping is found to be the most relevant method for the present catalysts. The kinetic parameters for the ORR (activity and selectivity) under quasi-steady-state conditions and their variation with Se modification were evaluated in potentiostatic flow-cell measurements. Modification of Ru/C catalyst by Se improves the O2 reduction activity and reduces the tendency for H2O2 formation in the technically relevant potential region of 0.6-0.8 VRHE, but even for the best catalyst compositions a significant ( approximately 0.2 VRHE) overpotential for O2 reduction on the RuSey/C catalysts remains compared to that for the Pt/C catalyst, and we find H2O2 yields of at least 1% at typical cathode operation potentials. Consequences of the relatively high H2O2 yields for membrane/electrode stability in practical applications are discussed.

  13. Investigation of high spin-polarization, magnetic, electronic and half-metallic properties in RuMn{sub 2}Ge and RuMn{sub 2}Sb Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Dinesh C.; Bhat, Idris Hamid, E-mail: idu.idris@gmail.com

    2015-03-15

    Highlights: • The present materials show magnetism and are ferromagnetic. • The materials show high spin-polarization and follow Slater–Pauling rule. • The materials are half-metallic and can be used as spintronic materials. - Abstract: Half-metallic ferromagnets RuMn{sub 2}Ge and RuMn{sub 2}Sb have been studied in stable F-43m phase. The optimized equilibrium lattice constants in F-43m phase were found to be 5.90 Å and 6.10 Å for RuMn{sub 2}Ge and RuMn{sub 2}Sb, respectively. The materials exhibit half-metallic city with an energy gap in the spin-down channel of 0.38 eV for RuMn{sub 2}Ge and 0.4 eV for RuMn{sub 2}Sb. The calculated total magnetic moments of 2.0 μ{sub B} per unit cell for RuMn{sub 2}Ge and 3.0 μ{sub B} per unit cell for RuMn{sub 2}Sb are in good agreement with Slater–Pauling rule. The magnetic moments of Mn-I and Mn-II mainly contribute to the total magnetic moment of the materials and are antiparallel to each other, hence predicting the signature of ferrimagnetism in RuMn{sub 2}Z alloys. The shifting of bands towards lower energies in spin-down channel for RuMn{sub 2}Sb may be due to the strong covalent character of bonding than RuMn{sub 2}Ge.

  14. Synthesis and Some Reactions of the Heterometallic C[subscript 7] Complex {Cp*(dppe)Ru}CCCCCCC{Co[subscript 3]([mu]-dppm)(CO)[subscript 7]}

    Energy Technology Data Exchange (ETDEWEB)

    Bruce, Michael I.; Cole, Marcus L.; Parker, Christian R.; Skelton, Brian W.; White, Allan H. (UWA); (Adelaide)

    2008-10-02

    The heterometallic carbon-chain complex {l_brace}Cp*(dppe)Ru{r_brace}CCCCCCC{l_brace}Co{sub 3}({mu}-dppm)(CO){sub 7}{r_brace} (1) has been obtained by three routes that involve assembly of the C{sub 7} chain by combination of appropriate C{sub 1} + C{sub 6}, C{sub 2} + C{sub 5}, or C{sub 3} + C{sub 4} precursors. The Cp analogue 2 and Co{sub 3}(CO){sub 9} cluster analogue 3 were obtained via the C{sub 2} + C{sub 5} and C{sub 1} + C{sub 6} routes, respectively. Reaction of 1 with PPh{sub 3} gave 4 via substitution of a Co{sub 3} cluster-bonded CO group. Addition of MeOTf to the second carbon from the Ru center in 1 afforded the vinylidene [{l_brace}Cp*(dppe)Ru{r_brace}CCMeCCCCC{l_brace}Co{sub 3}({mu}-dppm)(CO){sub 7}{r_brace}]OTf (5), while addition of tcne or tcnq across the central CC bond gave {l_brace}Cp*(dppe)Ru{r_brace}CCC[C(CN){sub 2}]C[C(CN){sub 2}]CCC{l_brace}Co{sub 3}({mu}-dppm)(CO){sub 7}{r_brace} (6) and {l_brace}Cp*(dppe)Ru{r_brace}CCC[C{sub 6}H{sub 4}C(CN){sub 2}]C[C(CN){sub 2}]CCC{l_brace}Co{sub 3}({mu}-dppm)(CO){sub 7}{r_brace} (7), respectively. The reaction between 1 and Fe 2(CO){sub 9} was more complex, the major product being {l_brace}Cp*(dppe)Ru{r_brace}CCC{l_brace}Fe{sub 3}(CO){sub 9}{r_brace}CCCC{l_brace}Co{sub 3}({mu}-dppm)(CO){sub 7}{r_brace} (8), accompanied by an Fe{sub 2}(CO){sub 6} derivative (9) of as yet undetermined structure. {l_brace}Cp*(dppe)Ru{r_brace}CCCCCCC{l_brace}Co{sub 2}Ni({mu}-dppm)(CO){sub 4}Cp{r_brace} (10) was obtained from the reaction with NiCp{sub 2}. An unstable adduct containing two Co{sub 2}(CO){sub 6} groups attached to the C{sub 7} chain was formed in reactions between 1 and Co{sub 2}(CO){sub 8}. XRD structural studies of 1, 2, 6-8, and 10 are reported. Electrochemical measurements suggest that there is some interaction between the two end groups, although this cannot presently be quantified. It is concluded that the C{sub 7} chain is long enough for the properties of the individual end caps to be preserved

  15. Frist-principles study of magnetic shape memory effect of new Heusler alloy RuMn2Sn%新型Heusler合金RuMn2Sn的磁性形状记忆的第一性原理研究

    Institute of Scientific and Technical Information of China (English)

    杨丽娟; 张加宏; 顾芳; 刘清倦; 张兆慧; 崔磊

    2013-01-01

    The crystal structure, electronic structure, magnetism and tetragonal distortions of new Heu-sler alloy RuMn2 Sn are calculated by the first-principles method based on the density functional theory. The calculated results show that: 1) in austenite, Mn atoms are the main contribuors to the magnetism in RuMn2Sn, and RuMn2 Sn alloys show ferrimagnetism due to antiparallel but unbalanced magnetic moments of Mn(A) atom and Mn(B) atom; 2) in the process of transforrm from XA-type cubic to a tetrgo-nal, RuMn2 Sn alloys exhibit a stable martensitic phase at c/a≈1. 23 and show the anti-ferromagnetic properties; 3)in austenite and martensite, the weak direct d-d exchange interaction between Mn(A) atom and Mn(B) atom is the main reason to maintain ferrimagnetic and antiferromagnetic coupling effect between Mn(A) atom and Mn(B) atom. Based on the results of calculation above, we can predict the well magnetic shape memory effect in RuMn2Sn.%采用基于密度泛函理论的第一性原理方法,对新型Heusler合金RuMn2Sn的晶体结构、电子结构、磁性、四方变形等性质进行了系统的研究.研究结果表明:1)在奥氏体态下,磁性原子Mn对体系总磁矩的贡献最大,其中Mn(A)和Mn(B)原子磁矩的值不等并且呈反平行耦合,导致RuMn2Sn具有稳定的亚铁磁基态,该结果与实验一致;2)由XA型立方结构至四方结构的四方变形中,发现c/a约为1.23处存在一个能量更低的稳定的马氏体相,其呈现反铁磁的特性;3)在奥氏体态和马氏体态下,Mn(A)和Mn(B)原子之间弱的d-d直接交换作用是维持它们之间亚铁磁和反铁磁耦合的主要原因.根据上述计算结果,预测RuMn2Sn具有良好的磁性形状记忆效应.

  16. Size dependence of structural parameters in fcc and hcp Ru nanoparticles, revealed by Rietveld refinement analysis of high-energy X-ray diffraction data.

    Science.gov (United States)

    Song, Chulho; Sakata, Osami; Kumara, Loku Singgappulige Rosantha; Kohara, Shinji; Yang, Anli; Kusada, Kohei; Kobayashi, Hirokazu; Kitagawa, Hiroshi

    2016-08-10

    To reveal the origin of the CO oxidation activity of Ruthenium nanoparticles (Ru NPs), we structurally characterized Ru NPs through Rietveld refinement analysis of high-energy X-ray diffraction data. For hexagonal close-packed (hcp) Ru NPs, the CO oxidation activity decreased with decreasing domain surface area. However, for face-centered cubic (fcc) Ru NPs, the CO oxidation activity became stronger with decreasing domain surface area. In comparing fcc Ru NPs with hcp Ru NPs, we found that the hcp Ru NPs of approximately 2 nm, which had a smaller domain surface area and smaller atomic displacement, showed a higher catalytic activity than that of fcc Ru NPs of the same size. In contrast, fcc Ru NPs larger than 3.5 nm, which had a larger domain surface area, lattice distortion, and larger atomic displacement, exhibited higher catalytic activity than that of hcp Ru NPs of the same size. In addition, the fcc Ru NPs had larger atomic displacements than hcp Ru NPs for diameters ranging from 2.2 to 5.4 nm. Enhancement of the CO oxidation activity in fcc Ru NPs may be caused by an increase in imperfections due to lattice distortions of close-packed planes and static atomic displacements.

  17. Soft Landing of Bare PtRu Nanoparticles for Electrochemical Reduction of Oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Grant E.; Colby, Robert J.; Engelhard, Mark H.; Moon, DaeWon; Laskin, Julia

    2015-08-07

    Magnetron sputtering of two independent Pt and Ru targets coupled with inert gas aggregation in a modified commercial source has been combined with soft landing of mass-selected ions to prepare bare 4.5 nm diameter PtRu alloy nanoparticles on glassy carbon electrodes with controlled size and morphology for electrochemical reduction of oxygen in solution. Employing atomic force microscopy (AFM) it is shown that the nanoparticles bind randomly to the glassy carbon electrode at a relatively low coverage of 7 x 104 ions µm-2 and that their average height is centered at 4 nm. Scanning transmission electron microscopy images obtained in the high-angle annular dark field mode (STEM-HAADF) further confirm that the soft-landed PtRu alloy nanoparticles are uniform in size and have a Ru core decorated with small regions of Pt on the surface. Wide-area scans of the electrodes using X-ray photoelectron spectroscopy (XPS) reveal the presence of both Pt and Ru in relative atomic concentrations of ~9% and ~33%, respectively. Deconvolution of the high energy resolution XPS spectra in the Pt4f and Ru3d regions indicates the presence of both oxidized Pt and Ru. The substantially higher loading of Ru compared to Pt and enrichment of Pt at the surface of the alloy nanoparticles is confirmed by wide-area analysis of the electrodes using time-of-flight medium energy ion scattering (TOF-MEIS) employing both 80 keV He+ and O+ ions. The activity of electrodes containing 7 x 104 ions µm-2 of bare 4.5 nm PtRu nanoparticles toward the electrochemical reduction of oxygen was evaluated employing cyclic voltammetry (CV) in 0.1 M HClO4 and 0.5 M H2SO4 solutions. In both electrolytes a pronounced reduction peak was observed during O2 purging of the solution that was not evident during purging with Ar. Repeated electrochemical cycling of the electrodes revealed little evolution in the shape or position of the voltammograms indicating high stability of the alloy nanoparticles supported on glassy

  18. A RuBisCO-mediated carbon metabolic pathway in methanogenic archaea

    Science.gov (United States)

    Kono, Takunari; Mehrotra, Sandhya; Endo, Chikako; Kizu, Natsuko; Matusda, Mami; Kimura, Hiroyuki; Mizohata, Eiichi; Inoue, Tsuyoshi; Hasunuma, Tomohisa; Yokota, Akiho; Matsumura, Hiroyoshi; Ashida, Hiroki

    2017-01-01

    Two enzymes are considered to be unique to the photosynthetic Calvin–Benson cycle: ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), responsible for CO2 fixation, and phosphoribulokinase (PRK). Some archaea possess bona fide RuBisCOs, despite not being photosynthetic organisms, but are thought to lack PRK. Here we demonstrate the existence in methanogenic archaea of a carbon metabolic pathway involving RuBisCO and PRK, which we term ‘reductive hexulose-phosphate' (RHP) pathway. These archaea possess both RuBisCO and a catalytically active PRK whose crystal structure resembles that of photosynthetic bacterial PRK. Capillary electrophoresis-mass spectrometric analysis of metabolites reveals that the RHP pathway, which differs from the Calvin–Benson cycle only in a few steps, is active in vivo. Our work highlights evolutionary and functional links between RuBisCO-mediated carbon metabolic pathways in methanogenic archaea and photosynthetic organisms. Whether the RHP pathway allows for autotrophy (that is, growth exclusively with CO2 as carbon source) remains unknown. PMID:28082747

  19. Catalytic water oxidation by mononuclear Ru complexes with an anionic ancillary ligand.

    Science.gov (United States)

    Tong, Lianpeng; Inge, A Ken; Duan, Lele; Wang, Lei; Zou, Xiaodong; Sun, Licheng

    2013-03-04

    Mononuclear Ru-based water oxidation catalysts containing anionic ancillary ligands have shown promising catalytic efficiency and intriguing properties. However, their insolubility in water restricts a detailed mechanism investigation. In order to overcome this disadvantage, complexes [Ru(II)(bpc)(bpy)OH2](+) (1(+), bpc = 2,2'-bipyridine-6-carboxylate, bpy = 2,2'-bipyridine) and [Ru(II)(bpc)(pic)3](+) (2(+), pic = 4-picoline) were prepared and fully characterized, which features an anionic tridentate ligand and has enough solubility for spectroscopic study in water. Using Ce(IV) as an electron acceptor, both complexes are able to catalyze O2-evolving reaction with an impressive rate constant. On the basis of the electrochemical and kinetic studies, a water nucleophilic attack pathway was proposed as the dominant catalytic cycle of the catalytic water oxidation by 1(+), within which several intermediates were detected by MS. Meanwhile, an auxiliary pathway that is related to the concentration of Ce(IV) was also revealed. The effect of anionic ligand regarding catalytic water oxidation was discussed explicitly in comparison with previously reported mononuclear Ru catalysts carrying neutral tridentate ligands, for example, 2,2':6',2″-terpyridine (tpy). When 2(+) was oxidized to the trivalent state, one of its picoline ligands dissociated from the Ru center. The rate constant of picoline dissociation was evaluated from time-resolved UV-vis spectra.

  20. Chemical doping effect in the LaRu3Si2 superconductor with a kagome lattice

    Science.gov (United States)

    Li, Baoxuan; Li, Sheng; Wen, Hai-Hu

    2016-09-01

    LaRu3Si2 is a superconductor with a kagome lattice and transition temperature of 7 K. By doping different rare-earth and transition-metal elements on the La and Ru sites, the evolution of superconductivity has been extensively investigated. It is found that, except for doping Fe to Ru sites, all other dopants with rare-earth (Y, Lu, and Ce) or transition metals (Ni, Cr, and Cu) seem to suppress superconducting transition temperature in LaRu3Si2 very slowly. The quick suppression of superconductivity by Fe doping can be described by the Abrikosov-Gorkov relation. By fitting and analyzing the magnetic susceptibility data under a high magnetic field with the Curie-Weiss law, we find that the effective magnetic moments for Ni and Cr doped samples are very small, indicating that these ions actually do not behave like strong magnetic scattering centers as Fe ions do in the present environment. Our experiments on systematically doped samples and related analysis indicate that the superconducting gap in LaRu3Si2 has no sign change.

  1. DNA-binding, cytotoxicity, cellular uptake, apoptosis and photocleavage studies of Ru(II) complexes.

    Science.gov (United States)

    N Deepika; C Shobha Devi; Y Praveen Kumar; K Laxma Reddy; P Venkat Reddy; D Anil Kumar; Surya S Singh; S Satyanarayana

    2016-07-01

    Two Ru(II) complexes [Ru(phen)2bppp](ClO4)2 (1) and [Ru(phen)27-Br-dppz](ClO4)2 (2) [phen=1,10 phenanthroline, 7-Br-dppz=7-fluorodipyrido[3,2-a:2',3'-c]phenazine, bppp=11-bromo-pyrido[2',3':5,6]pyrazino[2,3-f] [1,10]phenanthroline] have been synthesized and characterized by elemental analysis, ES-MS, (1)H-NMR, (13)C-NMR and IR. The in vitro cytotoxicity of the complexes examined against a panel of cancer cell lines (HeLa, Du145 and A549) by MTT method, both complexes show prominent anticancer activity against various cancer cells. Live cell imaging study and flow cytometric analysis demonstrate that both the complexes 1 and 2 could cross the cell membrane accumulating in the nucleus. Further, flow cytometry experiments showed that the cytotoxic Ru(II) complexes 1 and 2 induced apoptosis of HeLa tumor cell lines. Photo induced DNA cleavage studies have been performed and results indicate that both the complexes efficiently photo cleave pBR322 DNA. The binding properties of two complexes toward CT-DNA were investigated by various optical methods and viscosity measurements. The experimental results suggested that both Ru(II) complexes can intercalate into DNA base pairs. The complexes were docked into DNA-base pairs using the GOLD docking program.

  2. "Job-Sharing" Storage of Hydrogen in Ru/Li₂O Nanocomposites.

    Science.gov (United States)

    Fu, Lijun; Tang, Kun; Oh, Hyunchul; Manickam, Kandavel; Bräuniger, Thomas; Chandran, C Vinod; Menzel, Alexander; Hirscher, Michael; Samuelis, Dominik; Maier, Joachim

    2015-06-10

    A "job-sharing" hydrogen storage mechanism is proposed and experimentally investigated in Ru/Li2O nanocomposites in which H(+) is accommodated on the Li2O side, while H(-) or e(-) is stored on the side of Ru. Thermal desorption-mass spectroscopy results show that after loading with D2, Ru/Li2O exhibits an extra desorption peak, which is in contrast to Ru nanoparticles or ball-milled Li2O alone, indicating a synergistic hydrogen storage effect due to the presence of both phases. By varying the ratio of the two phases, it is shown that the effect increases monotonically with the area of the heterojunctions, indicating interface related hydrogen storage. X-ray diffraction, Fourier transform infrared spectroscopy, and nuclear magnetic resonance results show that a weak LiO···D bond is formed after loading in Ru/Li2O nanocomposites with D2. The storage-pressure curve seems to favor H(+)/H(-) over H(+)/e(-) mechanism.

  3. Conversion of isopropyl alcohol over Ru and Pd loaded N-doped carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Anas Benyounes; Mohamed Kacimi; Mahfoud Ziyad; Philippe Serp

    2014-01-01

    Ru and Pd (2 wt%) loaded on pure and on N-doped carbon nanotubes (N-CNTs) were prepared and tested using the isopropyl alcohol decomposition reaction as probe reaction. The presence of nitro-gen functionalities (pyridinic, pyrrolic, and quaternary nitrogen) on the nitrogen doped support induced a higher metal dispersion:Pd/N-CNT (1.8 nm)Ru/N-CNT (2.4 nm)<Ru/CNT (3.0 nm). The catalytic activity of the supports was determined first. Isopropyl alcohol conversion produces acetone on CNTs while on N-CNTs it led to both dehydration and dehydro-genation products. At 210 °C and in the presence of air, the isopropyl alcohol conversion was higher on the N-CNTs (25%) than on the CNTs (11%). The Pd loaded catalysts were more active and more selective than the Ru ones. At 115 °C, the Pd catalysts were 100%selective towards acetone for a conversion of 100%, whereas the Ru catalysts led to dehydration and dehydrogenation products. The nitrogen doping induced the appearance of redox properties when oxygen is present in the reaction mixture.

  4. Ru/Al Multilayers Integrate Maximum Energy Density and Ductility for Reactive Materials.

    Science.gov (United States)

    Woll, K; Bergamaschi, A; Avchachov, K; Djurabekova, F; Gier, S; Pauly, C; Leibenguth, P; Wagner, C; Nordlund, K; Mücklich, F

    2016-01-01

    Established and already commercialized energetic materials, such as those based on Ni/Al for joining, lack the adequate combination of high energy density and ductile reaction products. To join components, this combination is required for mechanically reliable bonds. In addition to the improvement of existing technologies, expansion into new fields of application can also be anticipated which triggers the search for improved materials. Here, we present a comprehensive characterization of the key parameters that enables us to classify the Ru/Al system as new reactive material among other energetic systems. We finally found that Ru/Al exhibits the unusual integration of high energy density and ductility. For example, we measured reaction front velocities up to 10.9 (± 0.33) ms(-1) and peak reaction temperatures of about 2000 °C indicating the elevated energy density. To our knowledge, such high temperatures have never been reported in experiments for metallic multilayers. In situ experiments show the synthesis of a single-phase B2-RuAl microstructure ensuring improved ductility. Molecular dynamics simulations corroborate the transformation behavior to RuAl. This study fundamentally characterizes a Ru/Al system and demonstrates its enhanced properties fulfilling the identification requirements of a novel nanoscaled energetic material.

  5. Effect of Lanthanum on RuBPCase Activity of Tobacco Seedlings

    Institute of Scientific and Technical Information of China (English)

    陈为钧; 顾月华; 王圣兵; 赵贵文

    2001-01-01

    The effects of La3+ on total activity and initial activity of RuBPCase (ribulose 1,5-bisphosphate carboxylase) in tobacco seedlings were studied. When treated with 20~80 μmol.L-1 LaCl3 in Hoagland solution by water culture, the activities of RuBPCase were raised, and the activation action of LaCl3 on initial activity was higher than that on total activity. But when the concentration of LaCl3 surpassed 80 μmol.L-1, the activities of RuBPCase were inhibited. It was also found that La3+ and Ce3+ can replace Mg2+ to activate the activity of RuBPCase in the enzymatic reaction, and the activation actions of La3+ and Ce3+ on the purified enzyme are higher than those on crude enzyme. The results indicate that La3+ activates the activity of RuBPCase in vivo as well as in vitro.

  6. Substituted tertiary phosphine Ru(II) organometallics: catalytic utility on the hydrolysis of etofibrate in pharmaceuticals.

    Science.gov (United States)

    Reddy, P Muralidhar; Shanker, Kanne; Rohini, Rondla; Sarangapani, M; Ravinder, Vadde

    2008-10-01

    Some new organometallics of ruthenium(II) of the type [RuCl2(COD)(CO)L] (1a-f) and [RuCl2(COD)L2] (2a-f) (where L is substituted tertiary phosphines), have been synthesized by using precursors [RuCl2(COD)(CO)(CH3CN)] (1) and [RuCl2(COD)(CH3CN)2] (2) with the substituted tertiary phosphine ligands in 1:1 and 1:2 molar ratio. The organometallics (2a-f) have been further reacted with carbonmonoxide to produce compounds of the type [RuCl2(CO)L2] (3a-f). These compounds were characterized by elemental analysis, IR, NMR (1H, 13C and 31P), mass and electronic spectral data. The catalytic activity of all these organometallics were studied and found that they are efficient catalysts for hydrolysis of etofibrate. The hydrolyzed product was separated by column chromatography and the percent yields are found in the range of 98.6-99.1%.

  7. Supported PtRu on mesoporous carbons for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Arbizzani, Catia; Beninati, Sabina; Soavi, Francesca; Varzi, Alberto; Mastragostino, Marina [University of Bologna, Department of Metal Science, Electrochemistry and Chemical Techniques, via San Donato 15, 40127 Bologna (Italy)

    2008-12-01

    We prepared and characterized several cryogel mesoporous carbons of different pore size distribution and report the catalytic activity of PtRu supported on mesoporous carbons of pore size >15 nm in passive and in active direct methanol fuel cells (DMFCs). At room temperature (RT), the specific maximum power of the passive DMFCs with mesoporous carbon/PtRu systems as anode was in the range 3-5 W g{sup -1}. Passive DMFC assembly and RT tests limit the performance of the electrocatalytic systems and the anodes were thus tested in active DMFCs at 30, 60 and 80 C. Their responses were also compared to those of commercial Vulcan carbon/PtRu. At 80 C, the specific maximum power of the active DMFC with C656/PtRu was 37 W g{sup -1} and the required amount of Pt per kW estimated at 0.4 V cell voltage was 31 g kW{sup -1}, a value less than half that of Vulcan carbon/PtRu. (author)

  8. The Corrosion Behaviour of WC-Co-Ru Alloys in Aggressive Chloride Media

    Directory of Open Access Journals (Sweden)

    J. H. Potgieter

    2014-01-01

    Full Text Available Hardmetals possess excellent wear resistance, making them suitable alloys in several industrial applications. Mine waters with both dissolved chloride and sulphate salts can be severely corrosive and can limit the application of hardmetal tools in the mining industry. Ru additions to these alloys can refine and improve selected mechanical properties, but its influence on the corrosion resistance is unknown. A series of WC-Co-Ru alloys was evaluated in different chloride containing media to investigate their corrosion resistance. Standard electrochemical corrosion tests, chronoamperometric measurements, and surface analyses with Raman spectroscopy were conducted. An increasing amount of Ru improves the corrosion resistance of all the alloys. The effect is not as dramatic as that observed with stainless steels containing Ru in corrosive media. In both corrosive media Ru decreased the cathodic Tafel constant and has a retarding influence on the cathodic part of the corrosion reaction. Raman analyses indicated the presence of tungsten oxide, hydrated tungsten oxide compounds, and CoO and Co3O4 formed on the alloy surfaces during the corrosion process.

  9. Electrochemical characterization of SnO{sub 2} electrodes doped with Ru and Pt

    Energy Technology Data Exchange (ETDEWEB)

    Berenguer, R. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Quijada, C. [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, 1, E-03801 Alcoy (Alicante) (Spain); Morallon, E. [Departamento de Quimica Fisica e Instituto Universitario de Materiales, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: morallon@ua.es

    2009-09-01

    Antimony-platinum doped tin dioxide electrodes supported on titanium have been prepared by thermal decomposition. The effect of the progressive replacement of Sb with Ru (x = 0.00; 3.25; 6.50; 13.00 at.%) on their electrochemical response in acid medium has been analysed by cyclic voltammetry. The morphology of the coatings was observed by scanning electron microscopy. Ti/SnO{sub 2}-Sb-Pt electrodes without Ru presented a cracked-mud structure, typical of oxide electrodes prepared by thermal decomposition. The introduction of Ru in the oxide layer modified the coating morphology. The roughness increased and passed through a maximum with the increase of Ru content. A relation between the surface morphology, the roughness factor, voltammetric charge and the electrochemical activity has been established. The mechanism and electrocatalytic activity towards the oxygen evolution reaction has been studied from Tafel measurements. The progressive introduction of Ru in the electrodes increased their electrocatalytic activity for the oxygen evolution reaction with a change on the mechanism from non-active to active electrodes. The electrocatalytic activity mainly depends on electronic factors.

  10. Classification of novel thiazole compounds for sensitizing Ru-polypyridine complexes for artificial light harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Johann [Institute of Photonic Technology (IPHT) Jena e.V., Albert-Einstein-Strasse 9, 07745 Jena (Germany); Menzel, Roberto; Weiss, Dieter [Institute for Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University Jena, Humboldtstr. 10, 07743 Jena (Germany); Dietzek, Benjamin, E-mail: benjamin.dietzek@uni-jena.d [Institute of Photonic Technology (IPHT) Jena e.V., Albert-Einstein-Strasse 9, 07745 Jena (Germany); Institute for Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena (Germany); Beckert, Rainer [Institute for Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University Jena, Humboldtstr. 10, 07743 Jena (Germany); Popp, Juergen [Institute of Photonic Technology (IPHT) Jena e.V., Albert-Einstein-Strasse 9, 07745 Jena (Germany); Institute for Physical Chemistry and Abbe Center of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, 07743 Jena (Germany)

    2011-06-15

    A systematic study of the Foerster resonance energy transfer (FRET) efficiency between thiazole dyes and a ruthenium-polypyridine complex is presented. While ruthenium-polypyridines are conventionally used in artificial light harvesting systems as primary electron donors, their application suffers from rather low extinction coefficients in the visible spectral range and an absorption gap between the {pi}{pi}{sup *} transitions of the ligands and the MLCT transitions. In this paper it is shown how thiazoles might help to circumvent theses issues. The absorption and emission spectra of the thiazole can be synthetically adjusted to fall into the absorption gap of the Ru dye and to efficiently overlap with the {sup 1}MLCT absorption of the complex, respectively. Thereby, the thiazoles might serve as antenna structures to funnel energy to the Ru-polypyridine unit, which finally can act as a photoactivated primary electron donor. Systematic investigations of the Foerster radii of representative thiazole Ru-polypyridine dye pairs corroborate this potential quantitatively. - Research highlights: {yields} First systematic study of Foerster radii in thiazole (donor)-Ru-polypyridine (acceptor) pairs. {yields} Large Foerster radii are observed (up to 40 A) comparable to systems optimized for FRET microscopy. {yields} Ru-polypyridine complexes dressed by thiazole-antennas as primary electron donors in artificial photosynthetic systems.

  11. On-line measurements of RuO{sub 4} during a PWR severe accident

    Energy Technology Data Exchange (ETDEWEB)

    Reymond-Laruinaz, S.; Doizi, D. [CEA, DEN, Departement de Physico-chimie, CEA/Saclay, 91191 Gif sur Yvette Cedex, (France); Manceron, L. [Societe Civile Synchrotron SOLEIL, L' Orme des Merisiers, St-Aubin BP48, 91192 Gif-sur-Yvette Cedex, (France); MONARIS, UMR 8233, Universite Pierre et Marie Curie, 4 Place Jussieu, case 49, F-75252 Paris Cedex 05, (France); Boudon, V. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Universite de Bourgogne, 9 avenue Alain Savary, BP 47870, F-21078 Dijon Cedex, (France); Ducros, G. [CEA, DEN, Departement d' Etudes des Combustibles, CEA/Cadarache, 13108 Saint-Paul-lez-Durance cedex, (France)

    2015-07-01

    After the Fukushima accident, it became essential to have a way to monitor in real time the evolution of a nuclear reactor during a severe accident, in order to react efficiently and minimize the industrial, ecological and health consequences of the accident. Among gaseous fission products, the tetroxide of ruthenium RuO{sub 4} is of prime importance since it has a significant radiological impact. Ruthenium is a low volatile fission product but in case of the rupture of the vessel lower head by the molten corium, the air entering into the vessel oxidizes Ru into gaseous RuO{sub 4}, which is not trapped by the Filtered Containment Venting Systems. To monitor the presence of RuO{sub 4} allows making a diagnosis of the core degradation and quantifying the release into the atmosphere. To determine the presence of RuO{sub 4}, FTIR spectrometry was selected. To study the feasibility of the monitoring, high-resolution IR measurements were realized at the French synchrotron facility SOLEIL on the infrared beam line AILES. Thereafter, theoretical calculations were done to simulate the FTIR spectrum to describe the specific IR fingerprint of the molecule for each isotope and based on its partial pressure in the air. (authors)

  12. Understanding RuO{sub 2}.xH{sub 2}O/carbon nanofibre composites as supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pico, F.; Rojas, R.M.; Amarilla, J.M.; Rojo, J.M. [Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Cientificas (CSIC), Cantoblanco, Sor Juana Ines de la Cruz 3, E-28049 Madrid (Spain); Ibanez, J. [Centro Nacional de Investigaciones Metalurgicas, CSIC, Avda Gregorio del Amo 8, E-28040 Madrid (Spain); Lillo-Rodenas, M.A.; Linares-Solano, A. [MCMA, Departamento de Quimica Inorganica, Universidad de Alicante, P.O. Box 99, E-03080 Alicante (Spain)

    2008-01-21

    Composites made from RuO{sub 2}.xH{sub 2}O particles supported on carbon nanofibres (CNF) have been prepared for supercapacitor electrodes. CNF, produced by Grupo Antolin Ing. SA. using a floating catalyst procedure was treated either in HCl or in HNO{sub 3}. Then the composites were obtained by impregnation of CNF with an aqueous RuCl{sub 3}.0.5H{sub 2}O solution followed by filtering and alkali solution treatment. Heat treatment at 150 C for 2 h was done. Specific capacitance of the composites has been measured and discussed on the basis of their RuO{sub 2}.xH{sub 2}O content and RuO{sub 2}.xH{sub 2}O particle size. The composites having RuO{sub 2}.xH{sub 2}O contents below 11 wt% show RuO{sub 2}.xH{sub 2}O particles, which grow from 2 to 4 nm as the RuO{sub 2}.xH{sub 2}O content increases. The specific capacitance of supported RuO{sub 2}.xH{sub 2}O, which can be very high (up to 840 F g{sup -1}), decreases as the RuO{sub 2}.xH{sub 2}O content increases and RuO{sub 2}.xH{sub 2}O particles grow. The composites having RuO{sub 2}.xH{sub 2}O contents above 11 wt% show RuO{sub 2}.xH{sub 2}O particles of nearly constant size (4 nm); the effect of increasing the RuO{sub 2}.xH{sub 2}O content is to increase the amount of particles but not the size of the particles. In these composites the specific capacitance of supported RuO{sub 2}.xH{sub 2}O is nearly constant (440 F g{sup -1}) and close to bare RuO{sub 2}.xH{sub 2}O (460 F g{sup -1}). (author)

  13. Increased Back-Bonding Explains Step-Edge Reactivity and Particle Size Effect for CO Activation on Ru Nanoparticles.

    Science.gov (United States)

    Foppa, Lucas; Copéret, Christophe; Comas-Vives, Aleix

    2016-12-28

    Carbon monoxide is a ubiquitous molecule, a key feedstock and intermediate in chemical processes. Its adsorption and activation, typically carried out on metallic nanoparticles (NPs), are strongly dependent on the particle size. In particular, small NPs, which in principle contain more corner and step-edge atoms, are surprisingly less reactive than larger ones. Hereby, first-principles calculations on explicit Ru NP models (1-2 nm) show that both small and large NPs can present step-edge sites (e.g., B5 and B6 sites). However, such sites display strong particle-size-dependent reactivity because of very subtle differences in local chemical bonding. State-of-the-art crystal orbital Hamilton population analysis allows a detailed molecular orbital picture of adsorbed CO on step-edges, which can be classified as flat (η(1) coordination) and concave (η(2) coordination) sites. Our analysis shows that the CO π-metal dπ hybrid band responsible for the electron back-donation is better represented by an oxygen lone pair on flat sites, whereas it is delocalized on both C and O atoms on concave sites, increasing the back-bonding on these sites compared to flat step-edges or low-index surface sites. The bonding analysis also rationalizes why CO cleavage is easier on step-edge sites of large NPs compared to small ones irrespective of the site geometry. The lower reactivity of small NPs is due to the smaller extent of the Ru-O interaction in the η(2) adsorption mode, which destabilizes the η(2) transition-state structure for CO direct cleavage. Our findings provide a molecular understanding of the reactivity of CO on NPs, which is consistent with the observed particle size effect.

  14. Unfavorable regions in the ramachandran plot: Is it really steric hindrance? The interacting quantum atoms perspective.

    Science.gov (United States)

    Maxwell, Peter I; Popelier, Paul L A

    2017-11-05

    Accurate description of the intrinsic preferences of amino acids is important to consider when developing a biomolecular force field. In this study, we use a modern energy partitioning approach called Interacting Quantum Atoms to inspect the cause of the φ and ψ torsional preferences of three dipeptides (Gly, Val, and Ile). Repeating energy trends at each of the molecular, functional group, and atomic levels are observed across both (1) the three amino acids and (2) the φ/ψ scans in Ramachandran plots. At the molecular level, it is surprisingly electrostatic destabilization that causes the high-energy regions in the Ramachandran plot, not molecular steric hindrance (related to the intra-atomic energy). At the functional group and atomic levels, the importance of key peptide atoms (Oi-1 , Ci , Ni , Ni+1 ) and some sidechain hydrogen atoms (Hγ ) are identified as responsible for the destabilization seen in the energetically disfavored Ramachandran regions. Consistently, the Oi-1 atoms are particularly important for the explanation of dipeptide intrinsic behavior, where electrostatic and steric destabilization unusually complement one another. The findings suggest that, at least for these dipeptides, it is the peptide group atoms that dominate the intrinsic behavior, more so than the sidechain atoms. © 2017 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. © 2017 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc.

  15. Topochemical reduction of the Ruddlesden-Popper phases Sr2Fe(0.5)Ru(0.5)O4 and Sr3(Fe(0.5)Ru(0.5))2O7.

    Science.gov (United States)

    Denis Romero, Fabio; Gianolio, Diego; Cibin, Giannantonio; Bingham, Paul A; d'Hollander, Jeanne-Clotilde; Forder, Susan D; Hayward, Michael A

    2013-10-01

    Reaction of the Ruddlesden-Popper phases Sr2Fe(0.5)Ru(0.5)O4 and Sr3(Fe(0.5)Ru(0.5))2O7 with CaH2 results in the topochemical deintercalation of oxide ions from these materials and the formation of samples with average compositions of Sr2Fe(0.5)Ru(0.5)O(3.35) and Sr3(Fe(0.5)Ru(0.5))2O(5.68), respectively. Diffraction data reveal that both the n = 1 and n = 2 samples consist of two-phase mixtures of reduced phases with subtly different oxygen contents. The separation of samples into two phases upon reduction is discussed on the basis of a short-range inhomogeneous distribution of iron and ruthenium in the starting materials. X-ray absorption data and Mössbauer spectra reveal the reduced samples contain an Fe(3+) and Ru(2+/3+) oxidation state combination, which is unexpected considering the Fe(3+)/Fe(2+) and Ru(3+)/Ru(2+) redox potentials, suggesting that the local coordination geometry of the transition metal sites helps to stabilize the Ru(2+) centers. Fitted Mössbauer spectra of both the n = 1 and n = 2 samples are consistent with the presence of Fe(3+) cations in square planar coordination sites. Magnetization data of both materials are consistent with spin glass-like behavior.

  16. Low-Energy Electronic Properties of Clean CaRuO3: Elusive Landau Quasiparticles

    Science.gov (United States)

    Schneider, M.; Geiger, D.; Esser, S.; Pracht, U. S.; Stingl, C.; Tokiwa, Y.; Moshnyaga, V.; Sheikin, I.; Mravlje, J.; Scheffler, M.; Gegenwart, P.

    2014-05-01

    We have prepared high-quality epitaxial thin films of CaRuO3 with residual resistivity ratios up to 55. Shubnikov-de Haas oscillations in the magnetoresistance and a T2 temperature dependence in the electrical resistivity only below 1.5 K, the coefficient of which is substantially suppressed in large magnetic fields, establish CaRuO3 as a Fermi liquid (FL) with an anomalously low coherence scale. At T >1.5 K non-Fermi-liquid (NFL) behavior is found in the electrical resistivity. The high sample quality allows access to the intrinsic electronic properties via THz spectroscopy. For frequencies below 0.6 THz, the conductivity is Drude-like and can be modeled by FL concepts; for higher frequencies, non-Drude behavior is found, which is inconsistent with FL predictions. This establishes CaRuO3 as a prime example of optical NFL behavior in the THz range.

  17. Photo-physical characterization of fluorophore Ru(bpy32+ for optical biosensing applications

    Directory of Open Access Journals (Sweden)

    E.L. Sciuto

    2015-12-01

    Full Text Available We studied absorption, emission and lifetime of the coordination compound tris(2,2′-bipyridylruthenium(II fluorophore (Ru(bpy32+ both dissolved in water solutions and dried. Lifetime measurements were carried out using a new detector, the Silicon Photomultiplier (SiPM, which is more sensitive and physically much smaller than conventional optical detectors, such as imager and scanner. Through these analyses and a morphological characterization with transmission electron microscopy, revealed its usability for sensor applications, in particular, as dye in optical DNA-chip technology, a viable alternative to the conventional CY5 fluorophore. The use of Ru(bpy32+ would solve some of the typical disadvantages related to Cy5’s application, such as self-absorption of fluorescence and photobleaching. In addition, the Ru(bpy32+ longer lifetime may play a key role in the definition of new optical DNA-chip.

  18. The Effect of PtRuIr Nanoparticle Crystallinity in Electrocatalytic Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Vladimir Linkov

    2013-04-01

    Full Text Available Two structural forms of a ternary alloy PtRuIr/C catalyst, one amorphous and one highly crystalline, were synthesized and compared to determine the effect of their respective structures on their activity and stability as anodic catalysts in methanol oxidation. Characterization techniques included TEM, XRD, and EDX. Electrochemical analysis using a glassy carbon disk electrode for cyclic voltammogram and chronoamperometry were tested in a solution of 0.5 mol L−1 CH3OH and 0.5 mol L−1 H2SO4. Amorphous PtRuIr/C catalyst was found to have a larger electrochemical surface area, while the crystalline PtRuIr/C catalyst had both a higher activity in methanol oxidation and increased CO poisoning rate. Crystallinity of the active alloy nanoparticles has a big impact on both methanol oxidation activity and in the CO poisoning rate.

  19. Models of spin structures in Sr sub 2 RuO sub 4

    CERN Document Server

    Ovchinnikov, A A

    2002-01-01

    The calculation of zones, the Fermi surfaces and spin susceptibilities of the RuO sub 4 three zone model of Sr sub 2 RuO sub 4 ruthenate plane for the states with different spin structures is carried out within the frames of the mean-field method. In particular, the spiral state with incommensurable vector Q 2 pi(1/3, 1/3) is studied. It proves to be the lower one by energy among other (para-, ferro-, antiferromagnetic and periodical) solutions. Besides, the Fermi shadow boundaries are revealed and explained in the spiral state apart from the alpha, beta, gamma basic sheets of the Fermi surface. The hypothesis on presence of the spiral structures with q = Q in the Sr sub 2 RuO sub 4 normal state and methods for its verification are discussed

  20. DMSO molecule as ancillary ligand in Ru-based catalysts for ring opening metathesis polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Santana, Sirlane A.A.; Carvalho Junior, Valdemiro P.; Lima-Neto, Benedito S. [Universidade de Sao Paulo, Sao Carlos (USP), SP (Brazil). Inst. de Quimica

    2010-07-01

    The ring-opening metathesis polymerization (ROMP) of norbornene (NBE) occurs in the presence of the fac-[RuCl{sub 2}(S-DMSO){sub 3}(O-DMSO)] complex and ethyldiazoacetate (5 {mu}L), where DMSO is S- or O-bonded dimethylsulfoxide. The yield is 62% (PDI = 1.64) at room temperature for 5 min and 88% (PDI 1.93) at 50 deg C for 30 min, with [NBE]/[Ru] = 516 in CHCl{sub 3}. The yield is 90% (PDI = 1.64) in the presence of NBu{sub 4}ClO{sub 4} at room temperature for 5 min. The complex is practically inactive when one or two molecules of DMSO are replaced by pyridine, imidazole, 2-methyl-imidazole or benzimidazole. The in situ formation of the catalytic species and the behavior of the DMSO molecules as ancillary ligands in the reactivity of the RuII complexes are discussed. (author)

  1. The activation mechanism of Ru-indenylidene complexes in olefin metathesis

    KAUST Repository

    Urbina-Blanco, César A.

    2013-05-08

    Olefin metathesis is a powerful tool for the formation of carbon-carbon double bonds. Several families of well-defined ruthenium (Ru) catalysts have been developed during the past 20 years; however, the reaction mechanism for all such complexes was assumed to be the same. In the present study, the initiation mechanism of Ru-indenylidene complexes was examined and compared with that of benzylidene counterparts. It was discovered that not all indenylidene complexes followed the same mechanism, highlighting the importance of steric and electronic properties of so-called spectator ligands, and that there is no single mechanism for the Ru-based olefin metathesis reaction. The experimental findings are supported quantitatively by DFT calculations. © 2013 American Chemical Society.

  2. Evolution of magnetism in Ru doped Na2IrO3

    Science.gov (United States)

    Mehlawat, Kavita; Singh, Yogesh

    2016-05-01

    We synthesized Ru doped single crystalline samples of the honeycomb iridate material Na2IrO3 and studied their magnetic properties using AC and DC magnetic susceptibility. The parent compound Na2IrO3 is a spin orbit driven Mott insulator with long range order below TN = 15 K. We find that even smallest substitution of Ru changes the antiferromagnetic long range order state to a spin glass like state indicating the fragile nature of magnetism in Na2IrO3. We track the freezing temperature Tg as a function of Ru concentration and the shift of Tg with frequency f of the ac modulation in AC susceptibility which is found to be very different from canonical spin-glasses like Cu-Mn.

  3. Stacking-dependent electronic property of trilayer graphene epitaxially grown on Ru(0001)

    Energy Technology Data Exchange (ETDEWEB)

    Que, Yande; Xiao, Wende, E-mail: wdxiao@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn; Chen, Hui; Wang, Dongfei; Du, Shixuan; Gao, Hong-Jun, E-mail: wdxiao@iphy.ac.cn, E-mail: hjgao@iphy.ac.cn [Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-12-28

    The growth, atomic structure, and electronic property of trilayer graphene (TLG) on Ru(0001) were studied by low temperature scanning tunneling microscopy and spectroscopy in combined with tight-binding approximation (TBA) calculations. TLG on Ru(0001) shows a flat surface with a hexagonal lattice due to the screening effect of the bottom two layers and the AB-stacking in the top two layers. The coexistence of AA- and AB-stacking in the bottom two layers leads to three different stacking orders of TLG, namely, ABA-, ABC-, and ABB-stacking. STS measurements combined with TBA calculations reveal that the density of states of TLG with ABC- and ABB-stacking is characterized by one and two sharp peaks near to the Fermi level, respectively, in contrast to the V-shaped feature of TLG with ABA-stacking. Our work demonstrates that TLG on Ru(0001) might be an ideal platform for exploring stacking-dependent electronic properties of graphene.

  4. Thermal stability of SrRuO{sub 3} epitaxial layers under forming-gas anneal

    Energy Technology Data Exchange (ETDEWEB)

    Halley, D.; Rossel, C.; Widmer, D.; Wolf, H.; Gariglio, S

    2004-06-15

    Perovskite SrRuO{sub 3} films are promising candidates as metallic electrodes in high-permittivity (high k) capacitors and possibly in fully epitaxial CMOS stacks. The thermal stability of SrRuO{sub 3} during forming-gas (FG) anneal is an important requirement and is investigated here by in situ X-ray diffraction (XRD) and electrical resistivity measurements. A weak and smooth increase of the resistivity is observed above 300 deg. C and is attributed to the effect of hydrogen diffusion. It is followed by a sharp transition at 500 deg. C into a highly resistive state due to the decomposition of the SrRuO{sub 3}. We found that the addition of about 1% O{sub 2} in the FG prevents both the onset of resistivity at 300 deg. C and the decomposition of the oxide.

  5. Promoted Ru on high-surface area graphite for efficient miniaturized production of hydrogen from ammonia

    DEFF Research Database (Denmark)

    Sørensen, Rasmus Zink; Klerke, Asbjørn; Quaade, Ulrich

    2006-01-01

    Promoted Ru/C catalysts for decomposition of ammonia are incorporated into micro-fabricated reactors for the first time. With the reported preparation technique, the performance is increased more than two orders of magnitude compared to previously known micro-fabricated reactors for ammonia decom...... studies of both ammonia synthesis and decomposition, and it is shown how proper promotion can facilitate ammonia decomposition at temperatures below 500 K.......Promoted Ru/C catalysts for decomposition of ammonia are incorporated into micro-fabricated reactors for the first time. With the reported preparation technique, the performance is increased more than two orders of magnitude compared to previously known micro-fabricated reactors for ammonia...... decomposition. The catalytic activities for production of hydrogen from ammonia are determined for different promoters and promoter levels on graphite supported ruthenium catalysts. The reactivity trends of the Ru/C catalysts promoted with Cs and Ba are in excellent agreement with those known from earlier...

  6. Study on hydrogen evolution performance of the carbon supported PtRu alloy film electrodes

    Institute of Scientific and Technical Information of China (English)

    YANG; Bin; LI; Yang; ZAN; Lin-han

    2005-01-01

    The carbon supported PtRu alloy film electrodes having Pt about 0.10 mg/cm2 or even less were prepared by ion beam sputtering method (IBSM). It was valued on the hydrogen analyse performance, the temperature influence factor and the stability by electroanalysis hydrogen analyse method. It was found that the carbon supported PtRu alloy film electrodes had higher hydrogen evolution performance and stability, such as the hydrogen evolution exchange current density (j0) was increase as the temperature (T) rised, and it overrun 150 mA/cm2 as the trough voltage in about 0.68V, and it only had about 2.8% decline in 500 h electrolytic process. The results demonstrated that the carbon supported PtRu alloy film electrodes kept highly catalytic activity and stability, and it were successfully used in pilot plant for producing H2 on electrolysis of H2S.

  7. The activation mechanism of Ru-indenylidene complexes in olefin metathesis.

    Science.gov (United States)

    Urbina-Blanco, César A; Poater, Albert; Lebl, Tomas; Manzini, Simone; Slawin, Alexandra M Z; Cavallo, Luigi; Nolan, Steven P

    2013-05-01

    Olefin metathesis is a powerful tool for the formation of carbon-carbon double bonds. Several families of well-defined ruthenium (Ru) catalysts have been developed during the past 20 years; however, the reaction mechanism for all such complexes was assumed to be the same. In the present study, the initiation mechanism of Ru-indenylidene complexes was examined and compared with that of benzylidene counterparts. It was discovered that not all indenylidene complexes followed the same mechanism, highlighting the importance of steric and electronic properties of so-called spectator ligands, and that there is no single mechanism for the Ru-based olefin metathesis reaction. The experimental findings are supported quantitatively by DFT calculations.

  8. H2 splitting on Pt, Ru and Rh nanoparticles supported on sputtered HOPG

    DEFF Research Database (Denmark)

    Fiordaliso, Elisabetta Maria; Murphy, Shane; Nielsen, R.M.;

    2012-01-01

    nm. The rate of hydrogen exchange is measured in the temperature range 40–200°C at 1bar, by utilization of the H–D exchange reaction. We find that the rate of hydrogen exchange increases with the particle diameter for all the metals, and that the rate for Ru and Rh is higher than for Pt. In the case...... adlayers on the terraces of the larger particles. Experiments are also carried out in the presence of 10ppm CO. Pt is found to be very sensitive to CO poisoning and the H–D exchange rate drops below the detection limit when CO is added to the gas mixture. In the case of Ru and Rh nanoparticles, CO...... decreases the splitting rate significantly, also at 200°C. The variation of the sensitivity to CO poisoning with particle diameter for Ru and Rh is found to be weak....

  9. Impurity-induced transition to a Mott insulator in Sr3 Ru2 O7

    Science.gov (United States)

    Mathieu, R.; Asamitsu, A.; Kaneko, Y.; He, J. P.; Yu, X. Z.; Kumai, R.; Onose, Y.; Takeshita, N.; Arima, T.; Takagi, H.; Tokura, Y.

    2005-09-01

    The electrical, magnetic, and structural properties of Sr3(Ru1-xMnx)2O7(0⩽x⩽0.2) are investigated. The parent compound Sr3Ru2O7 is a paramagnetic metal, critically close to magnetic order. We have found that, with a Ru-site doping by only a few percent of Mn, the ground state is switched from a paramagnetic metal to an antiferromagnetic insulator. Optical conductivity measurements show the opening of a gap as large as 0.1 eV, indicating that the metal-to-insulator transition is driven by the electron correlation. The complex low-temperature antiferromagnetic spin arrangement, reminiscent of those observed in some nickelates and manganites, suggests a long-range orbital order.

  10. Penning trap assisted decay spectroscopy of neutron-rich {sup 115}Ru

    Energy Technology Data Exchange (ETDEWEB)

    Kurpeta, J.; Plochocki, A.; Urban, W. [Warsaw University, Faculty of Physics, Warsaw (Poland); Elomaa, V.V.; Eronen, T.; Hakala, J.; Jokinen, A.; Karvonen, P.; Moore, I.; Penttilae, H.; Rahaman, S.; Rinta-Antila, S.; Rissanen, J.; Ronkainen, J.; Saastamoinen, A.; Sonoda, T.; Weber, C.; Aeystoe, J. [University of Jyvaeskylae, Department of Physics (Finland)

    2007-03-15

    Exotic, neutron-rich {sup 111}Mo and {sup 115}Ru nuclei, produced in proton-induced fission of {sup 238}U target, were separated with the IGISOL mass separator. The separator was coupled to the JYFLTRAP Penning trap to select the ions of a single, desired element out of the isobaric IGISOL beam. Monoisotopic samples of {sup 115}Ru and {sup 111}Mo ions were observed with a microchannel plate detector after the trap or were implanted on a catcher foil for gamma- and beta-ray coincidence spectroscopy. In spite of short data taking time new gamma transitions were identified in the beta decay of very neutron-rich {sup 115}Ru. (orig.)

  11. Supercritical water gasification of microalga Nannochloropsis over supported Ni and Ru catalysts

    Science.gov (United States)

    Wijenayake, A. G. B. S. P.; Hassan, M.; Komiyama, M.

    2016-11-01

    Supercritical water gasification (SCWG) of a marine microalga Nannochloropsis was performed in the presence and the absence of supported Ru and Ni catalysts at 385 °C and 26 MPa using a batch reactor. The product gas of the non-catalytic reaction mainly comprised of CO2 while that of catalytic reaction produced CH4, CO2, H2 and some C2-C4 compounds. The addition of catalysts enhanced the decomposition and conversion (water-gas shift and methanation) reactions, consequently increasing the total gasification efficiency up to 92% for 60 min reaction time. Between the supported Ru and Ni catalysts, Ru resulted in higher gasification efficiency than Ni. Catalyst deactivation during SCWG of Nannochloropsis was also examined.

  12. Magneto-structural study of a Cr-doped CaRuO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Ranjan, Rajeev; Garg, Rohini [Department of Materials Science, Indian Institute of Science, Bangalore 560012 (India); Senyshyn, Anatoliy [Institute for Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany); Hegde, M S [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Ehrenberg, Helmut [Institute for Complex Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Boysen, Hans, E-mail: rajeev@materials.iisc.ernet.i [Department fur Geo- und Umweltwissenschaften, Sektion Kristallographie, Ludwig Maximilians Universitaet, Am Coulombwall 1, D-85748 Garching, Muenchen (Germany)

    2009-08-12

    Temperature-dependent neutron powder diffraction, magnetization and XPS studies were carried out on an optimally Cr-doped CaRuO{sub 3}, i.e. CaRu{sub 0.85}Cr{sub 0.15}O{sub 3} (CRC-15). XPS data revealed that Cr exist in 3+ and 6+ oxidation states. The charge dissociation preserves the overall 4+ nominal charge of the Ru site. Although ferromagnetic correlations develop around 100 K, the system exhibits a large coercive field below 50 K. The unit cell volume exhibits negative thermal expansion below 50 K since the lattice expansion due to the magnetostrictive effect outweighs the thermal contraction due to the phonon-driven mechanism.

  13. Magneto-structural study of a Cr-doped CaRuO3

    Science.gov (United States)

    Ranjan, Rajeev; Garg, Rohini; Senyshyn, Anatoliy; Hegde, M. S.; Ehrenberg, Helmut; Boysen, Hans

    2009-08-01

    Temperature-dependent neutron powder diffraction, magnetization and XPS studies were carried out on an optimally Cr-doped CaRuO3, i.e. CaRu0.85Cr0.15O3 (CRC-15). XPS data revealed that Cr exist in 3+ and 6+ oxidation states. The charge dissociation preserves the overall 4+ nominal charge of the Ru site. Although ferromagnetic correlations develop around 100 K, the system exhibits a large coercive field below 50 K. The unit cell volume exhibits negative thermal expansion below 50 K since the lattice expansion due to the magnetostrictive effect outweighs the thermal contraction due to the phonon-driven mechanism.

  14. Magnetic and thermodynamic characterisation of α-RuCl{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Geyer, Maximilian; Corredor Bohorquez, Laura Theresa; Gass, Sebastian; Schottenhamel, Wolf; Wolter-Giraud, Anja [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden, IFW Dresden (Germany); Isaeva, Anna; Nowak, Domenic; Doert, Thomas [Technische Univ. Dresden (Germany); Buechner, Bernd [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung Dresden, IFW Dresden (Germany); Technische Univ. Dresden (Germany)

    2016-07-01

    The interplay between electronic correlations and spin-orbit coupling in heavy transition metal compounds has been intensively studied in the last years due to their interesting properties and unusual ground states like quantum spin liquids. Particularly α-RuCl{sub 3} seems to be a suitable candidate for the experimental realisation of the Kitaev-Model due to its J{sub eff} = 1/2 state and its layered honeycomb lattice of Ru{sup 3+} ions in the 4d{sup 5} configuration. This leads to highly anisotropic magnetic properties in this compound. We report on specific heat and magnetisation measurements for α-RuCl{sub 3} single crystals grown by means of chemical transport reactions. Furthermore magnetisation experiments under high pressure were conducted on this compound.

  15. Preparation and characterisation of Ru doped MgB2

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Holte, Olfert Joakim

    2013-01-01

    Samples with Mg1−xRuxB2 nominal stoichiometry were prepared by sintering at 800°C. The critical transition temperature decreases up to a substitution level of x≈0.015. A maximum solubility limit slightly in excess of 1at.% Ru for Mg is confirmed by energy dispersive spectroscopy measurements. From...... and beyond this limit, an unidentified phase appears in the X-ray diffraction patterns. Interestingly, the lattice parameters of the MgB2 phase are constant up to x=0.015, but start to decrease for higher Ru contents. This feature could be related to the fact that a Mg–Ru impurity phase results in a Mg...

  16. Magnetic phase diagrams based on static and dynamic magnetic behaviour in Ru-based superconducting ferromagnets.

    Science.gov (United States)

    Nigam, R; Pan, A V; Dou, S X

    2011-11-02

    In this work, we present magnetic phase diagrams of a RuSr(2)Eu(1.5)Ce(0.5)Cu(2)O(10-δ) (Ru-1222) superconducting ferromagnet derived from its static and dynamic magnetic responses, measured by temperature and field dependences of dc magnetization and nonlinear ac susceptibility in both low and high magnetic fields. Comparison of magnetic phase diagrams of phase pure and impure samples singles out the intrinsic and extrinsic magnetic features, naturally proposing a unified model of Ru-1222 magnetic behaviour. The results considered within the proposed interpretation indicate full agreement between static and dynamic properties which, if measured in combination, effectively complement each other, uncovering existing ambiguities.

  17. Spin-Glass-Like Behavior and Topological Hall Effect in SrRuO3/SrIrO3 Superlattices for Oxide Spintronics Applications.

    Science.gov (United States)

    Pang, Bin; Zhang, Lunyong; Chen, Y B; Zhou, Jian; Yao, Shuhua; Zhang, Shantao; Chen, Yanfeng

    2017-01-25

    The heterostructure interface provides a powerful platform for exploring rich emergent phenomena, such as interfacial superconductivity and nontrivial topological surface states. Here, SrRuO3/SrIrO3 superlattices were epitaxially synthesized. The magnetic and magneto-transport properties of these superlattices were characterized. A broad cusp-type splitting in the zero-field-cooling/field-cooling temperature-dependent magnetization and magnetization relaxation, which follows the modified stretched function model, accompanied by double hysteresis magnetization loops were demonstrated. These physical effects were modulated by the SrIrO3 layer thickness, which confirms the coexistence of interfacial spin glass and ferromagnetic ordering in the superlattices. In addition, the topological Hall effect was observed at low temperatures, and it is weakened with the increase of the SrIrO3 layer thickness. These results suggest that a noncoplanar spin texture is generated at the SrRuO3/SrIrO3 interfaces because of the interfacial Dzyaloshinskii-Moriya interaction. This work demonstrates that SrIrO3 can effectively induce interfacial Dzyaloshinskii-Moriya interactions in superlattices, which would serve as a mechanism to develop spintronic devices with perovskite oxides.

  18. LDA + slave-boson approach to the correlated electronic structure of the metamagnetic bilayer ruthenate Sr{sub 3}Ru{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Piefke, Christoph; Lechermann, Frank [Institut fuer Theoretische Physik, Universitaet Hamburg, 20355 Hamburg (Germany)

    2011-10-15

    The combination of the local-density approximation (LDA) with the rotationally invariant slave-boson theory (RISB) is used to investigate the realistic correlated electronic structure of Sr{sub 3}Ru{sub 2}O{sub 7}. From Wannier-downfolding the low-energy band structure to a three-band model for the Ru(t{sub 2g}) states, the interacting problem is solved including intra- and inter-orbital Hubbard terms as well as spin-flip and pair-hopping interactions. Therewith it is possible to obtain valuable insight into the orbital occupations, relevant local spin multiplets, and the fermiology with increasing correlation strength. Besides generic correlation-induced band-narrowing and -shifting, an intriguing quasiparticle structure close to the Fermi level is found in the neighborhood of the notorious {gamma}{sub 2} pocket in the Brillouin zone. Along the {gamma}-X direction in k-space, that structure appears very sensitive to electronic self-energy effects. The subtle sensitivity, connected also to its manifest multi-orbital character, may put this very low-energy structure in context with the puzzling metamagnetic properties of the compound. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Theoretical Insights into the Impact of Ru Catalyst Anchors on the Efficiency of Photocatalytic CO2 Reduction on Ta2O5.

    Science.gov (United States)

    Akimov, Alexey V; Jinnouchi, R; Shirai, S; Asahi, R; Prezhdo, Oleg V

    2015-06-18

    We present a computational study of the dynamical and electronic structure origins of the impact of anchoring groups, PO3H2, COOH, and OH, on the efficiency of photochemical CO2 reduction in Ru(di-X-bpy)(CO)2Cl2/Ta2O5 systems. Recent experimental studies indicate that the efficiency may not directly correlate with the driving force for electron transfer (ET) in these systems, prompting the need for further investigation of the role of anchor groups. Our analysis shows that there are at least two key roles of the anchor in determining the efficiency of CO2 reduction by the Ru complex. First, depending on local steric interactions, different tilting angles and their fluctuations may emerge for different anchors, affecting the magnitude of the donor-acceptor coupling. Second, depending on localization of acceptor states on the anchor, determined by the anchor's tendency to form conjugate subsystems, the yields of ET to the catalytic center may vary, directly affecting the photocatalytic efficiency. Finally, our calculations indicate that surface modeling with N-doping and many-body effects are needed to describe the ET process in the systems properly. N-doping imparts the Ta2O5 surface with a dipole moment, while Coulomb and exchange contributions to the electron-hole interaction can produce excitons that should be taken into account.

  20. Mechanistic Pathway in the Electrochemical Reduction of CO2 on RuO2

    DEFF Research Database (Denmark)

    Karamad, Mohammadreza; Hansen, Heine Anton; Rossmeisl, Jan

    2015-01-01

    RuO2 has been reported to reduce CO2 electrochemically to methanol at low overpotential. Herein, we have used density functional theory (DFT) to gain insight into the mechanism for CO2 reduction on RuO2(110). We have investigated the thermodynamic stability of various surface terminations in the ...

  1. Pt–Ru decorated self-assembled TiO2–carbon hybrid nanostructure for enhanced methanol electrooxidation

    Indian Academy of Sciences (India)

    K G Nishanth; P Sridhar; S Pitchumani; A K Shukla

    2013-06-01

    Porous titanium oxide–carbon hybrid nanostructure (TiO2–C) with a specific surface area of 350 m2/g and an average pore-radius of 21.8 Å is synthesized via supramolecular self-assembly with an in situ crystallization process. Subsequently, TiO2–C supported Pt–Ru electro-catalyst (Pt–Ru/TiO2–C) is obtained and investigated as an anode catalyst for direct methanol fuel cells (DMFCs). X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM) have been employed to evaluate the crystalline nature and the structural properties of TiO2–C. TEM images reveal uniform distribution of Pt–Ru nanoparticles (Pt−Ru = 1.5–3.5 nm) on TiO2–C. Methanol oxidation and accelerated durability studies on Pt–Ru/TiO2–C exhibit enhanced catalytic activity and durability compared to carbon-supported Pt–Ru. DMFC employing Pt–Ru/TiO2–C as an anode catalyst delivers a peak-power density of 91 mW/cm2 at 65 °C as compared to the peak-power density of 60 mW/cm2 obtained for the DMFC with carbon-supported Pt–Ru anode catalyst operating under similar conditions.

  2. Carbon supported Pd-Sn and Pd-Ru-Sn nanocatalysts for ethanol electro-oxidation in alkaline medium

    CSIR Research Space (South Africa)

    Modibedi, RM

    2011-04-01

    Full Text Available the coverage of the adsorbed ethoxy (CH3COads) species on the nanocatalyst surface, thus yielding an increase in current density. Pd-Sn/C displayed better electrocatalytic activity and stability towards poisoning than Pd-Ru-Sn/C and Pt-Ru/C (E-TEK Inc...

  3. Ni2P Makes Application of the PtRu Catalyst Much Stronger in Direct Methanol Fuel Cells.

    Science.gov (United States)

    Chang, Jinfa; Feng, Ligang; Liu, Changpeng; Xing, Wei

    2015-10-12

    PtRu is regarded as the best catalyst for direct methanol fuel cells, but the performance decay resulting from the loss of Ru seriously hinders commercial applications. Herein, we demonstrated that the presence of Ni2 P largely reduces Ru loss, which thus makes the application of PtRu much stronger in direct methanol fuel cells. Outstanding catalytic activity and stability were observed by cyclic voltammetry. Upon integrating the catalyst material into a practical direct methanol fuel cell, the highest maximum power density was achieved on the PtRu-Ni2P/C catalyst among the reference catalysts at different temperatures. A maximum power density of 69.9 mW cm(-2) at 30 °C was obtained on PtRu-Ni2P/C, which is even higher than the power density of the state-of-the-art commercial PtRu catalyst at 70 °C (63.1 mW cm(-2)). Moreover, decay in the performance resulting from Ru loss was greatly reduced owing to the presence of Ni2 P, which is indicative of very promising applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Synthesis, thermal properties and photoisomerization of trans-[Ru(NO)Py₂Cl₂(H₂O)]H₂PO₄·H₂O

    Indian Academy of Sciences (India)

    ALEXANDER N MAKHINYA; ILYA V KOROLKOV; MAXIM A IL’IN; IRAIDA A BAIDINA; PAVEL E PLUSNIN; EUGENI A MAXIMOVSKI; ELIZAVETA A BELETSKAYA; NINA I ALFEROVA

    2017-04-01

    The reaction of trans-[Ru(NO)Py₂Cl₂ (OH)] with concentrated o-phosphoric acid, after washing the mixture with diethyl ether, gave trans-[Ru(NO)Py₂Cl₂(H₂O)]H₂PO₄•2H₃PO₄•H₂O (I) in nearly quantitative yield. The structure of this compound was determined by X-ray diffraction analysis: space group P-1. Washing of I with ethanol afforded the dihydrophosphate salt trans-[Ru(NO)Py₂Cl₂ (H₂O)]H₂PO₄•H₂O (II) (yield 97%). The thermal decomposition of I and II in a helium atmosphere resulted in the formation of ruthenium phosphide RuP as a predominant component along with Ru₂P or RuP₂. Preliminary photoisomerization experiments for trans-[Ru(NO)Py₂Cl₂ (OH)] and trans-[Ru(NO)Py₂Cl₂ (H₂O)]H₂PO₄•H₂O suggested the presenceof metastable states. DSC experiments have been carried out for both compounds. The measured kinetic parameters for the metastable decay for trans-[Ru(NO)Py₂Cl₂ (H₂O)]H₂PO₄•H₂Owere Ea = 90.7± 2.4 kJ/mol, log10(k0/sec−1) = 18.9±0.6, and Td = 217 K.

  5. Selective Oxidation of CO in Excess H2 over Ru/Al2O3 Catalysts Modified with Metal Oxide

    Institute of Scientific and Technical Information of China (English)

    Xirong Chen; Hanbo Zou; Shengzhou Chen; Xinfa Dong; Weiming Lin

    2007-01-01

    The RU/Al2O3 catalysts modified with metal oxide (K2O and La2Os) were prepared via incipient wetness impregnation method from RUCl3.nH2O mixed with nitrate loading on Al2O3 support. The activity of catalysts was evaluated under simulative conditions for the preferential oxidation of CO (CO-PROX) from the hydrogen-rich gas streams produced by reforming gas, and the performances of catalysts were investigated by XRD and TPR. The results showed that the activity temperature of the modified catalysts RU-K2O/Al2O3 and Ru-La2Oa/Al2O3 were lowered approximately 30 ℃ compared with pure RU/AI2O3, and the activity temperature range was widened. The conversion of CO on RU-K2O/Al2O3 and Ru-La2O3/Al2O3 was above 99% at 140-160 ℃, suitable to remove CO in a hydrogen-rich gas and the selectivity of Ru-La2O3/Al2O3 was higher than that of RU-K2O/AI2O3 in the active temperature range. Slight methanation reaction was detected at 220 ℃ and above.

  6. Derivation of the liquidus surface projection for the Al-Pt-Ru system from as-cast samples

    CSIR Research Space (South Africa)

    Prins, SN

    2005-11-10

    Full Text Available .% platinum. Most of the other phases showed more limited solubilities for the ternary element: similar to RuAl2, similar to Pt2Al3 and similar to PtAl contained only about 2at.% of the third component similar to Ru 4Al13 has less than 1at.% solubility...

  7. The effect of peripheral bipyridine ligands on the photocatalytic hydrogen production activity of Ru/Pd catalysts

    NARCIS (Netherlands)

    Bindra, Gurmeet Singh; Schulz, Martin; Paul, Avishek; Soman, Suraj; Groarke, Robert; Inglis, Jane; Pryce, Mary T.; Browne, Wesley R.; Rau, Sven; Maclean, Brian J.; Vos, Johannes G.

    2011-01-01

    A pyrazine bridged ruthenium/palladium bimetallic photocatalyst with peripheral 4,4'-dicarboxyethyl-2,2'-bipyridine ligands, EtOOC-RuPd, is reported, together with its 2,2'-bipyridine analogue. Upon irradiation with visible light, EtOOC-RuPd catalyses the production of hydrogen gas whereas the compl

  8. Peroxydisulfate activation by [RuII(tpy)(pic)(H2O)]+. Kinetic, mechanistic and anti-microbial activity studies.

    Science.gov (United States)

    Chatterjee, Debabrata; Banerjee, Priyabrata; Bose, Jagadeesh C K; Mukhopadhyay, Sudit

    2012-03-07

    The oxidation of [Ru(II)(tpy)(pic)H(2)O](+) (tpy = 2,2',6',2''-terpyridine; pic(-) = picolinate) by peroxidisulfate (S(2)O(8)(2-)) as precursor oxidant has been investigated kinetically by UV-VIS, IR and EPR spectroscopy. The overall oxidation of Ru(II)- to Ru(IV)-species takes place in a consecutive manner involving oxidation of [Ru(II)(tpy)(pic)H(2)O](+) to [Ru(III)(tpy)(pic)(OH)](+), and its further oxidation of to the ultimate product [Ru(IV)(tpy)(pic)(O)](+) complex. The time course of the reaction was followed as a function of [S(2)O(8)(2-)], ionic strength (I) and temperature. Kinetic data and activation parameters are interpreted in terms of an outer-sphere electron transfer mechanism. Anti-microbial activity of Ru(II)(tpy)(pic)H(2)O](+) complex by inhibiting the growth of Escherichia coli DH5α in presence of peroxydisulfate has been explored, and the results of the biological studies have been discussed in terms of the [Ru(IV)(tpy)(pic)(O)](+) mediated cleavage of chromosomal DNA of the bacteria.

  9. Simulating Ru L3-edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, N.; Schoenlein, R. W.; Govind, Niranjan; Khalil, Munira

    2013-05-01

    Ruthenium L2,3-edge X-ray absorption (XA) spectroscopy probes transitions from core 2p orbitals to the 4d levels of the atom and is a powerful tool for interrogating the local electronic and molecular structure around the metal atom. However, a molecular-level interpretation of the Ru L2,3-edge spectral lineshapes is often complicated by spin–orbit coupling (SOC) and multiplet effects. In this study, we develop spin-free time-dependent density functional theory (TDDFT) as a viable and predictive tool to simulate the Ru L3-edge spectra. We successfully simulate and analyze the ground state Ru L3-edge XA spectra of a series of RuII and RuIII complexes: [Ru(NH3)6]2+/3+, [Ru(CN)6]4-/3-, [RuCl6]4-/3-, and the ground (1A1) and photoexcited (3MLCT) transient states of [Ru(bpy)3]2+ and Ru(dcbpy)2(NCS)2 (termed N3). The TDDFT simulations reproduce all the experimentally observed features in Ru L3-edge XA spectra. The advantage of using TDDFT to assign complicated Ru L3-edge spectra is illustrated by its ability to identify ligand specific charge transfer features in complex molecules. We conclude that the B3LYP functional is the most reliable functional for accurately predicting the location of charge transfer features in these spectra. Experimental and simulated Ru L3-edge XA spectra are presented for the transition metal mixed-valence dimers [(NC)5MII-CN-RuIII(NH3)5]- (where M = Fe or Ru) dissolved in water. We explore the spectral signatures of electron delocalization in Ru L3-edge XA spectroscopy and our simulations reveal that the inclusion of explicit solvent molecules is crucial for reproducing the experimentally determined valencies, highlighting the importance of the role of the solvent in transition metal charge transfer chemistry.

  10. Stopping the growth of particles to silica-supported mono-nuclear Ru hydride surface species by tuning silica with surface silanes

    Energy Technology Data Exchange (ETDEWEB)

    Berthoud, Romain; Fenet, Bernard; Lukens, Wayne; Pelzer, Katrin; Basset, Jean-Marie; Candy, Jean-Pierre; Coperet, Christophe

    2007-07-11

    Tuning silica by replacing surface silanols with silanes allows chemical grafting of Ru(COD)(COT) through a covalent Ru-Si bond, as evidenced by elemental analysis, IR spectroscopy and EXAFS. Treatment of these surface species under H2 at 300 oC yields a mononuclear Ru hydride species, without any sintering of the metal according to TEM and EXAFS analyses. This supported system displays catalytic properties different from those of supported Ru particles (2 nm), selectively hydrogenating olefins over aromatics.

  11. Evaluation of nanostructured Pt-Ru catalyst for application in DMFC

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo, A.L.; Gamboa, S.A. [Centro de Investigacion en Energia-UNAM, Morelos (Mexico); Sebastien, P.J. [Centro de Investigacion en Energia-UNAM, Morelos (Mexico)]|[Chiapas Politecnica Univ., Chiapas (Mexico); Morgado, J.; Montoya, J.A. [IMP, Eje Central Lazaro Cardenas, (Mexico); Savadogo, O. [Ecole Polytechnique, Montreal, PQ (Canada). Laboratoire d' electrochimie et de materiaux energetiques

    2006-07-01

    Slow methanol oxidation kinetics and the poisoning of the anode catalyst are the major factors that limit the performance of the direct methanol fuel cell (DMFC). Catalysts with higher catalytic activity are needed in order to overcome these challenges. Although platinum (Pt) is a good catalyst for methanol oxidation, it can be highly affected by carbon monoxide (CO) reaction intermediates. Superior catalytic activity occurs in Pt based alloys, such as platinum ruthenium (Pt-Ru), platinum molybdenum (Pt-Mo), platinum tin (Pt-Sn), and platinum osmium (Pt-Os). This is due to the bifunctional mechanism and/or by the electronic effect, which indicates a promotional effect of the alloyed metal on Pt. The most studied binary system is the Pt-Ru (ruthenium), which has shown the best catalytic activity. There are many factors that influence the physical properties and the electrochemical performance of the Pt-Ru catalyst. These include the preparation method; the atomic ratio between platinum and ruthenium; the nature of the catalyst support; and, an optional heat treatment. Other important factors such as the particle size, the morphology, the electrochemically active area, and the crystalline phase influence the physical properties. In this study, nanostructured Pt-Ru catalysts were fabricated and evaluated physicochemically and electrochemically for its use in direct methanol fuel cell (DMFC). The catalysts were synthesized from the carbonyl compounds of Pt and Ru via a pyrolysis-condensation reaction. The high resolution results showed a homogenous distribution of the nanostructured catalysts on Vulcan support. The catalyst was evaluated by XRD, HRTEM, electrochemical impedance spectroscopy and the methanol oxidation on the catalyst was studied using volt-amperometry. The performance of the catalyst was found to be similar or better than the commercial one. It was concluded that it is possible to synthesize Pt-Ru/C with good morphological characteristics and improve it

  12. 2,5-Dioxido-1,4-benzoquinonediimine (H2L2-), a hydrogen-bonding noninnocent bridging ligand related to aminated topaquinone: different oxidation state distributions in complexes [{(bpy)2Ru}2(mu-H2L)]n (n=0,+,2+,3+,4+) and [{(acac)2Ru}2(mu-H2L)]m (m=2-,-,0,+,2+).

    Science.gov (United States)

    Kar, Sanjib; Sarkar, Biprajit; Ghumaan, Sandeep; Janardanan, Deepa; van Slageren, Joris; Fiedler, Jan; Puranik, Vedavati G; Sunoj, Raghavan B; Kaim, Wolfgang; Lahiri, Goutam Kumar

    2005-08-19

    The symmetrically dinuclear title compounds were isolated as diamagnetic [(bpy)2Ru(mu-H2L)Ru(bpy)2](ClO4)2 (1-(ClO4)2) and as paramagnetic [(acac)2Ru(mu-H2L)Ru(acac)2] (2) complexes (bpy=2,2'-bipyridine; acac- = acetylacetonate = 2,4-pentanedionato; H2L = 2,5-dioxido-1,4-benzoquinonediimine). The crystal structure of 22 H2O reveals an intricate hydrogen-bonding network: Two symmetry-related molecules 2 are closely connected through two NH(H2L2-)O(acac-) interactions, while the oxygen atoms of H2L2- of two such pairs are bridged by an (H2O)8 cluster at half-occupancy. The cluster consists of cyclic (H2O)6 arrangements with the remaining two exo-H2O molecules connecting two opposite sides of the cyclo-(H2O)6 cluster, and oxido oxygen atoms forming hydrogen bonds with the molecules of 2. Weak antiferromagnetic coupling of the two ruthenium(III) centers in 2 was established by using SQUID magnetometry and EPR spectroscopy. Geometry optimization by means of DFT calculations was carried out for 1(2+) and 2 in their singlet and triplet ground states, respectively. The nature of low-energy electronic transitions was explored by using time-dependent DFT methods. Five redox states were reversibly accessible for each of the complexes; all odd-electron intermediates exhibit comproportionation constants K(c)>10(8). UV-visible-NIR spectroelectrochemistry and EPR spectroscopy of the electrogenerated paramagnetic intermediates were used to ascertain the oxidation-state distribution. In general, the complexes 1n+ prefer the ruthenium(II) configuration with electron transfer occurring largely at the bridging ligand (mu-H2Ln-), as evident from radical-type EPR spectra for 13+ and (+. Higher metal oxidation states (iii, iv) appear to be favored by the complexes 2m; intense long-wavelength absorption bands and RuIII-type EPR signals suggest mixed-valent dimetal configurations of the paramagnetic intermediates 2+ and 2-.

  13. Synthesis and Electronic Structure of Ru2(Xap)4(Y-gem-DEE) Type Compounds: Effect of Cross-Conjugation.

    Science.gov (United States)

    Forrest, William P; Choudhuri, Mohommad M R; Kilyanek, Stefan M; Natoli, Sean N; Prentice, Boone M; Fanwick, Phillip E; Crutchley, Robert J; Ren, Tong

    2015-08-03

    Reported in this Article are the preparation and characterization of a series of new Ru2(II,III) compounds bearing one cross-conjugated σ-geminal-diethynylethene ligand (gem-DEE), namely, Ru2(Xap)4(Y-gem-DEE) (Xap = N,N'-anilinopyridinate (ap) or 2-(3,5-dimethoxy)anilinopyridinate (DiMeOap), and Y = Si(i)Pr3 (1) or H (2)) and [Ru2(ap)4]2(μ-gem-DEE) (3). Compounds 1-3 were characterized by spectroscopic and voltammetric techniques as well as the single crystal X-ray diffraction study of 2a. The X-ray structural data of 2a and the spectroscopic/voltammetric data of compounds 1 and 2 indicate that the gem-DEE ligands are similar to simple alkynyls in their effects on the molecular and electronic structures of the Ru2(Xap)4 moiety. Similar to the previously studied [Ru2(ap)4]2(μ-C2n) type compounds, dimer 3 exhibits pairwise 1e(-) oxidations and reductions, albeit the potential splits within the pair (ΔE1/2) are significantly smaller than those of [Ru2(ap)4]2(μ-C4). The electronic absorption spectra of the reduced and oxidized derivatives of 1a and 3 were determined using spectroelectrochemistry methods. No discernible intervalence charge transfer transition (IVCT) was detected in the near-IR spectrum for either 3(-) or 3(+), suggesting that the Ru2-Ru2 coupling in these mixed-valence states is weak. DFT calculations on a model compound of 3 yielded six singly occupied molecular orbitals (SOMOs), which have Ru2 contributions similar to those previously calculated for the [Ru2(ap)4]2(μ-C2n) type compounds. Among six SOMOs, SOMO-2 is the only one containing substantial dπ-π(gem-DEE) character across the entire Ru2-μ-gem-DEE-Ru2 linkage, which explains the weakened Ru2-Ru2 coupling.

  14. Electronic and optical response of functionalized Ru(II) complexes: joint theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Kilina, Svetlana [Los Alamos National Laboratory; Tretiak, Sergei [Los Alamos National Laboratory; Sykora, Milan [Los Alamos National Laboratory; Albert, Victor [UNIV OF FLORIDA; Badaeva, Ekaterina [UNIV OF WASHINGTON; Koposov, Alexey [UNIV OF WASHINGTON

    2008-01-01

    New photovoltaic and photocatalysis applications have been recently proposed based on the hybrid Ru(II)-bipyridine-complex/semiconductor quantum dot systems. In order to attach the Ru(II) complex to the surface of a semiconductor, a linking bridge -- a carboxyl group -- needs to be added to one or two of the 2,2'-bipyridine (bpy) ligands. Such changes in the ligand structure affect electronic and optical properties and, consequently, the charge transfer reactivity of Ru(II)-systems. In this study, we analyze the effects brought by functionalization of bipyridine ligands with the methyl, carboxyl, and carboxilate groups on the electronic structure and optical response of the [Ru(bpy){sub 3}]{sup 2+} complex. First principle calculations based on density functional theory (DFT) and time dependent DFT (TDDFT) are used to simulate the ground and excited-state properties, respectively, of functionalized Ru-complexes in the gas phase and acetonitrile solution. In addition, an effective Frenkel exciton model is used to explain the optical activity and splitting patterns of the low-energy excited states in all molecules. All theoretical results nicely complement and allow for detailed interpretation of experimental absorption spectra of Ru-complexes that have been done in parallel with our theoretical investigations. We found that the carboxyl group breaks the degeneracy of two low-energy optically bright excited states and red-shifts the absorption spectrum, while leaves ionization and affinity energies of complexes almost unchanged. Experimental studies show that deprotonation of the carboxyl group in the Ru-complexes results in a slight blue shift and decrease of oscillator strengths of the low energy absorption peaks. Comparison of experimental and theoretical linear response spectra of deprotonated complexes demonstrate strong agreement if the theoretical calculations are performed with the addition of a dielectric continuum model. A polar solvent is found to

  15. Noise and structural properties of reactively sputtered RuO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jevtic, Milan M. [Institute of Physics, Beograd, 11080 Zemun, Pregrevica 118 (Serbia and Montenegro); Jelenkovic, Emil V. [Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong (China)]. E-mail: enemil@inet.polyu.edu.hk; Tong, K.Y. [Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong (China); Pang, G.K.H. [Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong (China)

    2006-02-21

    Ruthenium dioxide thin films were reactively rf sputtered on SiO{sub 2}/Si substrates and annealed in the temperature range from 150 to 500 deg. C. The structural and morphological properties of the films were investigated using Raman spectroscopy, transmission electron microscopy and atomic force microscopy. The increase of grain size was improved with annealing temperature. After annealing at 500 deg. C, the roughening of the RuO{sub 2}/SiO{sub 2} interface was observed. The electrical behaviour was analysed by resistivity, thermal coefficient of resistance and low frequency noise. Good correlation between structural and electrical properties of RuO{sub 2} films was established.

  16. Highly selective CO methanation over amorphous Ni-Ru-B/ZrO2 catalyst

    Institute of Scientific and Technical Information of China (English)

    Qi Hai Liu; Xin Fa Dong; Wei Ming Lin

    2009-01-01

    Amorphous Ni-Ru-B/ZrO2 catalyst was prepared by the means of chemical reduction, and selective CO methanation as a strategy for CO removal in fuel processing applications was investigated over the amorphous Ni-Ru-B/ZrO2 catalyst. The result showed that, at the temperature of 210-230 ℃, the catalyst was shown to be capable of reducing CO in a hydrogen-rich reformate to less than 10 ppm, while keeping the CO2 conversion below 1.55% and the hydrogen consumption below 6.50%.

  17. Ammonia synthesis over a Ru(0001) surface studied by density functional calculations

    DEFF Research Database (Denmark)

    Logadottir, Ashildur; Nørskov, Jens Kehlet

    2003-01-01

    In this paper we present DFT studies of all the elementary steps in the synthesis of ammonia from gaseous hydrogen and nitrogen over a ruthenium crystal. The stability and configurations of intermediates in the ammonia synthesis over a Ru(0001) surface have been investigated, both over a flat...... surface and over a stepped surface. The calculations show that the step sites on the surface are much more reactive than the terrace sites. The DFT results are then used to study the mechanism of promotion by alkalies over the Ru(0001) and to determine the rate-determining step in the synthesis of ammonia...

  18. Imaging of vortex chains in Sr{sub 2}RuO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Dolocan, V.O.; Veauvy, C.; Liu, Y.; Servant, F.; Lejay, P.; Mailly, D.; Hasselbach, K

    2004-05-01

    Sr{sub 2}RuO{sub 4} is an unconventional superconductor with a superconducting transition temperature of {approx}1.5 K. The formation of vortex chains in Sr{sub 2}RuO{sub 4} is observed, they have been directly imaged by {mu}SQUID force microscopy at low temperature. Ginzburg-Landau theory for anisotropic superconductors is in qualitative agreement with the observed dependencies of the vortex chains on the variation of the tilting angle or the amplitude of the external magnetic field.

  19. Solvolysis of the Tumor-Inhibiting Ru(III)-Complex trans-Tetrachlorobis(Indazole)Ruthenate(III)

    OpenAIRE

    Pieper, Thomas; Peti, Wolfgang; Keppler, Bernhard K.

    2000-01-01

    The ruthenium(III) complex Hlnd trans-[RuCl4,(ind)2], with two trans-standing indazole (ind) ligands bound to ruthenium via nitrogen, shows remarkable activity in different tumor models in vitro and in vivo. The solvolysis of the complex trans-[RuCl4,(ind)2]- has been investigated by means of spectroscopic techniques (UV/vis, NMR)in different solvents. We investigated the indazolium as well as the sodium salt, the latter showing improved solubility in water. In aqueous acetonitrile and ethano...

  20. Photocatalytic Reduction of Carbon Dioxide with Modify Pd, Ru on TiO2 Surface

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Photocatalytic reduction of CO2 to organic compounds was reduction in semiconductor suspension system under simulated solar in laboratory. TiO2 load catalysts were prepared in different ways, and they were used in photocatalytic reduction of CO2 . Experimental results show that the photocatalytic activity can be improve by dressing Pd, Ru on TiO2 Surface and is obvious different when catalysts were prepared in different ways. The photocatalytic mechanism of dressing Pd on TiO2 Surface; dressing Pd and Ru on TiO2 Surface were also discussed in this paper.