WorldWideScience

Sample records for nacl structure compounds

  1. Phase transitions in antiferromagnets with a NaCl structure

    Energy Technology Data Exchange (ETDEWEB)

    Kassan-Ogly, F.A. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, ul. S.Kovalevskoi 18, Ekaterinburg 620219 (Russian Federation)]. E-mail: felix.kassan-ogly@imp.uran.ru; Filippov, B.N. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, ul. S.Kovalevskoi 18, Ekaterinburg 620219 (Russian Federation)

    2006-05-15

    A revised derivation scheme of possible magnetic structures in an FCC lattice with the nearest- and next-nearest-neighbor interactions taken into account is proposed. A model of simultaneous magnetic and structural phase transitions of the first order is developed for antiferromagnets with a NaCl structure and with a strong cubic magnetic anisotropy on the base of synthesis of magnetic modified 6-state Potts model and theoretical models of structural phase transitions in cubic crystals. It is shown that the high-temperature diffuse magnetic scattering of neutrons transforms into magnetic Bragg reflections below Neel point.

  2. Phase transitions in antiferromagnets with a NaCl structure

    Science.gov (United States)

    Kassan-Ogly, F. A.; Filippov, B. N.

    2006-05-01

    A revised derivation scheme of possible magnetic structures in an FCC lattice with the nearest- and next-nearest-neighbor interactions taken into account is proposed. A model of simultaneous magnetic and structural phase transitions of the first order is developed for antiferromagnets with a NaCl structure and with a strong cubic magnetic anisotropy on the base of synthesis of magnetic modified 6-state Potts model and theoretical models of structural phase transitions in cubic crystals. It is shown that the high-temperature diffuse magnetic scattering of neutrons transforms into magnetic Bragg reflections below Néel point.

  3. Fabrication of Large Binary Colloidal Crystals with a NaCl Structure

    National Research Council Canada - National Science Library

    E. C. M. Vermolen; A. Kuijk; L. C. Filion; M. Hermes; J. H. J. Thijssen; M. Dijkstra; A. van Blaaderen; Charles M. Lieber

    2009-01-01

    .... Here, we present methods for growing binary colloidal crystals with a NaCl structure from relatively heavy, hard-spherelike, micrometer-sized silica particles by exploring the following external fields...

  4. The Synthesis of Imidazoline Derivative Compounds as Corrosion Inhibitor towards Carbon Steel in 1% NaCl Solution

    Directory of Open Access Journals (Sweden)

    Deana Wahyuningrum

    2008-03-01

    Full Text Available Oleic imidazoline is one of the nitrogen containing heterocyclic compounds that has been widely used as commercial corrosion inhibitor, especially in minimizing the carbon dioxide induced corrosion process in oilfield mining. In this present work, some imidazoline derivative compounds have been synthesized utilizing both conventional and microwave assisted organic synthesis (MAOS methods, in order to determine their corrosion inhibition properties on carbon steel surface. The MAOS method is more effective in synthesizing these compounds than the conventional method regarding to the higher chemical yields of products (91% to 94% and the shorter reaction times (7 to 10 minutes. The characterization of corrosion inhibition activities of the synthesized products towards carbon steel in 1% NaCl solution was determined by the Tafel plot method. The corrosion inhibition activities of compound 1b ((Z-2-(2-(heptadec-8-enyl-4,5-dihydroimidazol-1-ylethanamine, 2b ((Z-2-(2-(heptadec-8-enyl-4,5-dihydroimidazol-1-ylethanol and 3b (2-(2-heptadecyl-4,5-dihydroimidazol-1-ylethanamine at 8 ppm concentration in 1% NaCl solution are, respectively, 32.18%, 39.59% and 12.73%. The heptadec-8-enyl and hydroxyethyl substituents at C(2 and N(1 position of imidazoline ring, respectively, gave the most effective corrosion inhibition activity towards carbon steel compared to the presence of other substituents. The increase in concentrations of compound 1b, 2b and 3b in 1% NaCl solution tends to improve their corrosion inhibition activities. Based on the analysis of the free Gibbs adsorption energy (DG0ads values of compound 1b, 2b and 3b (-32.97, -34.34 and -31.27 kJ/mol, respectively, these compounds have the potential to interact with carbon steel through semi-physiosorption or semi-chemisorption.

  5. Structural Stabilities of Ordered Arrays of Nb4 Clusters on NaCl(100) Surface

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Chun; ZHANG Jian-Hua; WEN Yu-Hua; ZHU Zi-Zhong

    2009-01-01

    Adsorption of ordered (2 × 2) arrays of Nb4 clusters on the insulating surface of NaCl(100) is studied by the first-principles calculations within the density functional theory. The calculations on the relaxed geometries and cohesive energies show that both the tetrahedron and quadrangle-Nb4 can be stably adsorbed on this substrate, which may have important applications. The adsorption of quadrangle-Nb4 on the NaCl(100) surface is more stable than that of tetrahedron-Nb4. Both the Nb4 clusters studied and a single Nb atom prefer the top site of the Cl atom in the NaCl(100) surface. Electronic structure analysis suggests that the interactions between the Nb4 dusters and the substrate are weak.

  6. Effects of inhibitors and NaCl on the oxidation of reduced inorganic sulfur compounds by a marine acidophilic, sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH.

    Science.gov (United States)

    Kamimura, Kazuo; Higashino, Emi; Kanao, Tadayoshi; Sugio, Tsuyoshi

    2005-02-01

    The effect of NaCl and the pathways of the oxidation of reduced inorganic sulfur compounds were studied using resting cells and cell-free extracts of Acidithiobacillus thiooxidans strain SH. This isolate specifically requires NaCl for growth. The oxidation of sulfur and sulfite by resting cells was strongly inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide. Carbonylcyanide m-chlorophenyl-hydrazone and monensin were also relatively strong inhibitors. Thiosulfate-oxidizing activity was not inhibited by these uncouplers. Valinomycin did not inhibit the oxidation of sulfur compounds. NaCl stimulated the sulfur- and sulfite-oxidizing activities in resting cells but not in cell-free extracts. The tetrathionate-oxidizing activity in resting cells was slightly stimulated by NaCl, whereas it did not influence the thiosulfate-oxidizing activity. Sulfide oxidation was biphasic, suggesting the formation of intermediate sulfur. The initial phase of sulfide oxidation was not affected by NaCl, whereas the subsequent oxidation of sulfur in the second phase was Na+-dependent. A model is proposed for the role of NaCl in the metabolism of reduced sulfur compounds in A. thiooxidans strain SH.

  7. Electrolytic reduction of Nantong coal and model compounds with oxygenic functional groups in an aqueous NaCl solution

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei; YAO Li-ping; LIN Juan; ZONG Zhi-min

    2008-01-01

    Electrolytic reductions of oxygenic functional groups (OFGs) on coal surface and coal model compounds with OFGs in an aqueous NaCl solution are studied by electrochemical methods combined with GC/MS, GC and FTIR analyses. Different elec-trode reactions, their corresponding potentials and dynamic equations during the processes are investigated. The results show that benzoic acid, benzaldehyde, benzalcohol and hypnone are reduced to benzaldehyde and benzalcohol, methoxybenzene and benzal-cohol, toluene and styrene, respectively, at the cathode. The corresponding electrode potentials and dynamic equations are deter-mined. The electrolytic reduction also leads to an increase in the contents of hydroxyl groups and aliphatic moieties and a corre-sponding decrease in those of carboxyl and carbonyl groups in Nantong coal, a high-sulfur coal, an enhancement in the flotation desulfurization of the coal. ER also reduces organic sulfur and FeS2 in the coal.

  8. Influence of partial replacement of NaCl with KCl on profiles of volatile compounds in dry-cured bacon during processing

    Science.gov (United States)

    This study investigated the influence of partial substitution of NaCl with KCl on the formation of volatile compounds in bacons during processing using a purge and trap dynamic headspace GC/MS system. Three substitutions were 0% KCl (I), 40% KCl (II), and 70% KCl (III). The profiles of the volatile ...

  9. Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Liscio, F; Maret, M; Doisneau-Cottignies, B [Science et Ingenierie des Materiaux et Procedes (SIMaP), INP-Grenoble/CNRS/UJF, BP 75, 38402 Saint-Martin d' Heres (France); Makarov, D; Albrecht, M [Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz (Germany); Roussel, H, E-mail: mireille.maret@simap.grenoble-inp.fr [Consortium des Moyens Technologiques Communs, INP-Grenoble, BP 75, 38402 Saint-Martin d' Heres (France)

    2010-02-10

    A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L1{sub 0} chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L1{sub 0} variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L1{sub 0} phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.

  10. Growth, structure and magnetic properties of FePt nanostructures on NaCl(001) and MgO(001)

    Science.gov (United States)

    Liscio, F.; Makarov, D.; Maret, M.; Doisneau-Cottignies, B.; Roussel, H.; Albrecht, M.

    2010-02-01

    A comparison of the structural and magnetic properties of FePt nanostructures grown at different temperatures on NaCl(001) and MgO(001) substrates is presented. A strong influence of the deposition temperature on the epitaxial growth as well as on the size distribution of FePt nanostructures grown on NaCl substrates is observed. In spite of a large lattice mismatch between FePt and NaCl, a 'cube-over-cube' growth of nanostructures with a narrow size distribution was achieved at 520 K. Moreover, the growth of FePt nanostructures on NaCl(001) is not preceded by the formation of a wetting layer as observed on MgO(001). The higher degree of L10 chemical ordering in FePt nanostructures grown on MgO(001) accompanied by the absence of L10 variants with an in-plane tetragonal c-axis indicates that the tensile epitaxial stress induced by the MgO substrate is a key factor in the formation of the L10 phase with an out-of-plane c-axis. Superparamagnetic behavior is revealed for the FePt nanostructures grown on NaCl(001) due to their small size and relatively poor chemical order.

  11. The structures of binary compounds

    CERN Document Server

    Hafner, J; Jensen, WB; Majewski, JA; Mathis, K; Villars, P; Vogl, P; de Boer, FR

    1990-01-01

    - Up-to-date compilation of the experimental data on the structures of binary compounds by Villars and colleagues. - Coloured structure maps which order the compounds into their respective structural domains and present for the first time the local co-ordination polyhedra for the 150 most frequently occurring structure types, pedagogically very helpful and useful in the search for new materials with a required crystal structure. - Crystal co-ordination formulas: a flexible notation for the interpretation of solid-state structures by chemist Bill Jensen. - Recent important advances in unders

  12. Morphological, Physiological, and Structural Responses of Two Species of Artemisia to NaCl Stress

    Directory of Open Access Journals (Sweden)

    Zhi-Yong Guan

    2013-01-01

    Full Text Available Effects of salt stress on Artemisia scoparia and A. vulgaris “Variegate” were examined. A. scoparia leaves became withered under NaCl treatment, whereas A. vulgaris “Variegate” leaves were not remarkably affected. Chlorophyll content decreased in both species, with a higher reduction in A. scoparia. Contents of proline, MDA, soluble carbohydrate, and Na+ increased in both species under salt stress, but A. vulgaris “Variegate” had higher level of proline and soluble carbohydrate and lower level of MDA and Na+. The ratios of K+/Na+, Ca2+/Na+, and Mg2+/Na+ in A. vulgaris “Variegate” under NaCl stress were higher. Moreover, A. vulgaris “Variegate” had higher transport selectivity of K+/Na+ from root to stem, stem to middle mature leaves, and upper newly developed leaves than A. scoparia under NaCl stress. A. vulgaris “Variegate” chloroplast maintained its morphological integrity under NaCl stress, whereas A. scoparia chloroplast lost integrity. The results indicated that A. scoparia is more sensitive to salt stress than A. vulgaris “Variegate.” Salt tolerance is mainly related to the ability of regulating osmotic pressure through the accumulation of soluble carbohydrates and proline, and the gradient distribution of K+ between roots and leaves was also contributed to osmotic pressure adjustment and improvement of plant salt tolerance.

  13. Magnetic and structural transitions in crystals with a structure of the NaCl type

    Science.gov (United States)

    Kassan-Ogly, F. A.; Filippov, B. N.

    2009-04-01

    A model of simultaneous magnetic and structural first-order transitions in antiferromagnets with a strong cubic magnetic anisotropy has been constructed on the basis of a synthesis of magnetic modified 6-state and 8-state Potts models and the theoretical model of structural phase transitions in cubic crystals. A revised scheme has been suggested for the derivation of possible magnetic structures in the fcc lattice with allowance for competing interactions between the nearest and next-nearest neighbors. A calculation of the temperature evolution of high-temperature diffuse magnetic scattering of neutrons has been carried out to show that the mechanism of a magnetic transition at the Néel point is caused by the transformation of diffuse magnetic scattering into magnetic Bragg peaks.

  14. Electrochemical behaviour of Cu-30Ni alloy in 3 per cent NaCl (pH = 9.25) solution in presence of triazole derivatives compounds

    Energy Technology Data Exchange (ETDEWEB)

    Es-Salah, K. [Ibno Tofai Univ., Laboratoire d' Electrochimie des Etudes de Corrosion et d' Environnement, Faculte des Sciences, Kenitra (Morocco)]|[Paris Univ., Paris (France). Laboratoire de Physique des Liquides et Electrochimie; Benmessoud, M.; Hajjaji, N.; Srhiri, A. [Ibno Tofai Univ., Laboratoire d' Electrochimie des Etudes de Corrosion et d' Environnement, Faculte des Sciences, Kenitra (Morocco); Takenouti, H. [Paris Univ., Paris (France). Laboratoire de Physique des Liquides et Electrochimie

    2006-07-01

    This study investigated the electrochemical behaviour of of a copper-nickel alloy solution without and with the addition of triazole derivatives compounds. In particular, the rotating disc electrode technique was used to examine a mixture of Cu-30Ni in aerated 3 per cent NaCl solution of pH 9.25 with 3 - amino - 1,2,4 triazole, bitriazole. The corrosion rate and the kenitic charge that control the interface process were determined by potentiodynamic measurements and electrochemical impedance spectroscopy. The results showed that all the compounds influenced the cathodic and anodic process, indicating corrosion inhibition for the alloy. Electrochemical testing showed that the inhibition efficiency increased with increasing concentration and increasing immersion time at open circuit potential. It was demonstrated that the inhibition mixture provided more protection than ATA and BiTA.

  15. Crystal structure analysis of intermetallic compounds

    Science.gov (United States)

    Conner, R. A., Jr.; Downey, J. W.; Dwight, A. E.

    1968-01-01

    Study concerns crystal structures and lattice parameters for a number of new intermetallic compounds. Crystal structure data have been collected on equiatomic compounds, formed between an element of the Sc, Ti, V, or Cr group and an element of the Co or Ni group. The data, obtained by conventional methods, are presented in an easily usable tabular form.

  16. Electronic structure and magnetism in actinide compounds

    Energy Technology Data Exchange (ETDEWEB)

    Durakiewicz, T. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)]. E-mail: tomasz@lanl.gov; Joyce, J.J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lander, G.H. [JRC, Institute of Transuranium Elements, Postfach 2340, 76125 Karlsruhe (Germany); Olson, C.G. [Ames Laboratory, Iowa State University, Ames, Iowa 5011 (United States); Butterfield, M.T. [Lawrence Livermoore National Laboratory, Livermoore, CA 94550 (United States); Guziewicz, E. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Batista, C.D. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Arko, A.J. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Morales, L. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Mattenberger, K. [Laboratorium fur Festkorperphysik, ETH, CH-8093, Zurich (Switzerland); Vogt, O. [Laboratorium fur Festkorperphysik, ETH, CH-8093, Zurich (Switzerland)

    2006-05-01

    A close relationship between electronic structure and magnetic properties is observed in actinide compounds. The exact nature of this relationship is under investigation. We present examples of a direct link between electronic structure and ordered magnetic moment and/or magnetization. Specifically, results obtained for cubic U, Np and Pu compounds and quasi-2D U compounds are be presented. In the case of cubic compounds, a direct relationship between binding energy of valence band features and magnetic moment will be discussed. A Stoner-like mechanism and simple mean-field explanation is proposed for ferromagnetic UTe.

  17. The structure of carbon monoxide adsorbed on the NaCl(100) surface—a combined LEED and DFT-D/vdW-DF study.

    Science.gov (United States)

    Vogt, Jochen; Vogt, Birgit

    2014-12-07

    The structure of the first layer CO adsorbed on NaCl(100) is investigated experimentally by means of quantitative low-energy electron diffraction at 25 K, and theoretically by means of density functional theory. Consistent with earlier helium atom diffraction results, the monolayer structure has p(2×1) symmetry with a glide-plane along the longer axis of the unit cell. The structure analysis confirms the binding of CO via the carbon end to the NaCl(100) surface. The vertical distance of carbon above Na(+) is 2.58 ± 0.08 Å, in good agreement with geometry optimizations based on dispersion-corrected density functional theory, and 0.15 Å lower than predicted in calculations based on the nonlocal van der Waals density functional.

  18. Pressure-induced phase transition and stability of EuO and EuS with NaCl structure

    Indian Academy of Sciences (India)

    Atul Gour; Sadhna Singh; R K Singh; M Singh

    2008-07-01

    We have predicted the phase transition pressures and corresponding relative volume changes of EuO and EuS having NaCl-type structure under high pressure using three-body interaction potential (TBIP) approach. In addition, the conditions for relative stability in terms of modified Born criterion has been checked. Our calculated results of phase transitions, volume collapses and elastic behaviour of these compounds are found to be close to the experimental results. This shows that the inclusion of three-body interaction effects makes the present model suitable for high pressure studies.

  19. Effects of Na2SO4 or NaCl on sonochemical degradation of phenolic compounds in an aqueous solution under Ar: Positive and negative effects induced by the presence of salts.

    Science.gov (United States)

    Uddin, Md Helal; Nanzai, Ben; Okitsu, Kenji

    2016-01-01

    Sonochemical degradation of 4-chlorophenol, phenol, catechol and resorcinol was studied under Ar at 200 kHz in the absence and presence of Na2SO4 or NaCl. The rates of sonochemical degradation in the absence of salts decreased in the order 4-chlorophenol>phenol>catechol>resorcinol and this order was in good agreement with the order of log P (partition coefficient) value of each phenolic compound. The effects of salts on the rates of sonochemical degradation consisted of no effect or slight negative or positive effects. We discussed these unclear results based on two viewpoints: one was based on the changes in pseudo hydrophobicity and/or diffusion behavior of phenolic compounds and the other was based on the changes in solubility of Ar gas. The measured log P value of each phenolic compound slightly increased with increasing salt concentration. In addition, the dynamic surface tension for 4-chlorophenol aqueous solution in the absence and presence of Na2SO4 or NaCl suggested that phenolic compounds more easily accumulated at the interface region of bubbles at higher salt concentration. These results indicated that the rates of sonochemical degradation should be enhanced by the addition of salts. On the other hand, the calculated Ar gas solubility was confirmed to decrease with increasing salt concentration. The yield of H2O2 formed in the presence of Na2SO4 or NaCl decreased with increasing salt concentration. These results suggested that sonochemical efficiency decreased with decreasing gas amount in aqueous solution: a negative effect of salts was observed. Because negative and positive effects were induced simultaneously, we concluded that the effects of salts on the rates of sonochemical degradation of phenolic compounds became unclear. The products formed from sonochemical degradation of 4-chlorophenol were also characterized by HPLC analysis. The formation of phenol and 4-chloro-1,3-dihydroxy benzene was confirmed and these concentrations were affected by the

  20. Theoretical study of the electron paramagnetic resonance parameters and local structure for the tetragonal Ir2+ centre in NaCl

    Indian Academy of Sciences (India)

    Y-X Hu; S-Y Wu; X-F Wang; P Xu

    2010-04-01

    The electron paramagnetic resonance (EPR) parameters (the factors, hyperfine structure constants and the superhyperfine parameters) for the tetragonal Ir2+ centre in NaCl are theoretically investigated from the perturbation formulas of these parameters for a 5d7 ion in tetragonally elongated octahedra. This impurity centre is attributed to the substitutional [IrCl6]4- cluster on host Na+ site, associated with the 4% relative elongation along the 4-axis due to the Jahn–Teller effect. Despite the ionicity of host NaCl, the [IrCl6]4- cluster still exhibits moderate covalency and then the ligand orbital and spin-orbit coupling contributions should be taken into account. In addition, the theoretical EPR parameters based on the Jahn–Teller elongation show good agreement with the observed values.

  1. Sub micrometric fibrillar structures of codoped poly aniline obtained by co-oxidation using the NaCl O/ammonium peroxydisulfate system: synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Osorio F, J. E.; Gomez Y, C.; Hernandez P, M. A.; Corea T, M. L., E-mail: josorio@ipn.mx [IPN, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, U. P. Adolfo Lopez Mateos, Av. Instituto Politecnico Nacional s/n, Col. San Pedro Zacatenco, 07738 Mexico D. F. (Mexico)

    2013-07-01

    A mixture of ammonium peroxydisulfate and sodium hypochlorite (NaCl O) (co-oxi dating system) were used to obtain poly aniline (PANi) doped with HCl and camphorsulfonic acid (CsA) (co-doping). The effect of HCl/CsA ratio added during polymerization structure, morphology and electrical conductivity of the conducting polymer was investigated. When NaCl O is used, the polymerization rate is substantially increased and the morphology changes from micrometric granular to nano metric fibrillar. CsA was used as complementary dopant but also to improve the solubility of PANi in common solvents. However, results suggest that quinone-like heterocycles containing carbonyl radicals as well as phenazine-type aromatic rings might be impeding an efficient doping in detriment of the conductivity. For the characterization X-Ray diffraction analysis, UV visible spectroscopy and scanning electron microscopy were used. (Author)

  2. Electrochemical preparation of NiAl intermetallic compound from solid oxides in molten CaCl{sub 2} and its corrosion behaviors in NaCl aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Yin Huayi; Yu Tang; Tang Diyong; Ruan Xuefeng; Zhu Hua [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Wang Dihua, E-mail: wangdh@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Stoichiometric NiAl powder was prepared by one-step electrolysis of solid NiO-NiAl{sub 2}O{sub 4} in molten CaCl{sub 2}. Black-Right-Pointing-Pointer The energy consumption was as low as 6.1 kWh (kg-NiAl){sup -1}. Black-Right-Pointing-Pointer Uniform distribution and co-reduction of Ni and Al oxide played key role for Al retaining. Black-Right-Pointing-Pointer Electrolytic NiAl powder was made into dense NiAl rod by spark plasma sintering (SPS). Black-Right-Pointing-Pointer Obtained NiAl rod was self-passivated in NaCl solution and show very high corrosion resistance. - Abstract: Nickel aluminide powders were prepared by direct electrochemical reduction of solid mixture of NiO-NiAl{sub 2}O{sub 4} (Ni:Al = 1:1 in mol) precursor in molten CaCl{sub 2} at 850 Degree-Sign C. The reduction process of the solid oxide cathode was investigated by analyzing the intermediate products using X-ray diffraction (XRD) and scanning electron microscopy (SEM). It reveals that nickel is preferentially reduced and it benefits to prevent aluminum leaving from the cathode. The products obtained at the constant cell voltage electrolysis of 3.0 V for more than 4 h were stoichiometric NiAl. The energy consumption could be as low as 6.1 kWh (kg-NiAl){sup -1} based on the applied cell voltage and the consumed electrolysis charge. Furthermore, the NiAl powders were made into a dense rod by spark plasma sintering (SPS) technique. The corrosion behaviors of the NiAl rod in 0.5 mol L{sup -1} NaCl aqueous solution at room temperature were investigated by polarization curve and ac impedance measurements. It was found that the NiAl rod had satisfactory anti-corrosion ability in the solution.

  3. The structure of N2 adsorbed on the rumpled NaCl(100) surface--a combined LEED and DFT-D study.

    Science.gov (United States)

    Vogt, Jochen

    2012-11-07

    The structure of N(2) physisorbed on the NaCl(100) single crystal surface is investigated by means of quantitative low-energy electron diffraction (LEED) in combination with dispersion corrected density functional theory (DFT-D). In the temperature range between 20 K and 45 K, a p(1 × 1) structure is observed in the LEED experiment. According to the structure analysis based on the measured diffraction spot intensity profiles, the N(2) molecules are adsorbed over the topmost Na(+) ions. The experimental distance of the lower nitrogen to the Na(+) ion underneath is (2.55 ± 0.07) Å; the corresponding DFT-D value is 2.65 Å. The axes of the molecules are tilted (26 ± 3)° with respect to the surface normal, while in the zero Kelvin optimum structure from DFT-D, the molecules have a perpendicular orientation. The experimental monolayer heat of adsorption, deduced from a Fowler-Guggenheim kinetic model of adsorption is -(13.6 ± 1.6) kJ mol(-1), including a lateral molecule-molecule interaction energy of -(2.0 ± 0.4) kJ mol(-1). The zero Kelvin adsorption energy from DFT-D, including zero point energy correction, is -15.6 kJ mol(-1); the molecule-molecule interaction is -2.4 kJ mol(-1). While the rumpling of the NaCl(100) surface is unchanged upon adsorption of nitrogen, the best-fit root mean square thermal displacements of the ions in the topmost substrate layer are significantly reduced.

  4. Tritium labeling of organic compounds deposited on porous structures

    Science.gov (United States)

    Ehrenkaufer, Richard L. E.; Wolf, Alfred P.; Hembree, Wylie C.

    1979-01-01

    An improved process for labeling organic compounds with tritium is carried out by depositing the selected compound on the extensive surface of a porous structure such as a membrane filter and exposing the membrane containing the compound to tritium gas activated by the microwave discharge technique. The labeled compound is then recovered from the porous structure.

  5. Structural studies of naturally occurring toxicogenic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Springer, J. P.

    1977-10-01

    The paralytic shellfish poison (PSP), saxitoxin, is a neurotoxin isolated from Alaska butter clams (Saxidomus giganteus), mussels (Mytilus californianus) and axenic cultures of the dinoflagellate Gonyaulax catenella. The structure of saxitoxin has been determined through the use of single crystal X-ray diffraction. It possesses a unique tricyclic arrangement of atoms containing two guanidinium moieties and also a hydrated ketone. The relative stereochemistry is presented as well as the absolute configuration. The chemical constitution of a tremorgenic metabolite, paxilline, isolated from extracts of the fungus Penicillium paxilli Bainier has been determined. Paxilline represents a previously unreported class of natural compounds formed by the combination of tryptophan and mevalonate subunits. The complete stereostructure of two other fungal metabolites, paspaline and paspalicine, closely related to paxilline but isolated from Claviceps paspali Stammes have also been determined and are presented. The stereochemistries of paxilline, paspaline and paspalicine are identical at corresponding chiral centers.

  6. Temperature-dependent solubility transition of Na₂SO₄ in water and the effect of NaCl therein: solution structures and salt water dynamics.

    Science.gov (United States)

    Bharmoria, Pankaj; Gehlot, Praveen Singh; Gupta, Hariom; Kumar, Arvind

    2014-11-06

    Dual, aqueous solubility behavior of Na2SO4 as a function of temperatures is still a natural enigma lying unresolved in the literature. The solubility of Na2SO4 increases up to 32.38 °C and decreases slightly thereafter at higher temperatures. We have thrown light on this phenomenon by analyzing the Na2SO4-water clusters (growth and stability) detected from temperature-dependent dynamic light scattering experiments, solution compressibility changes derived from the density and speed of sound measurements, and water structural changes/Na2SO4 (ion pair)-water interactions observed from the FT-IR and 2D DOSY (1)H NMR spectroscopic investigations. It has been observed that Na2SO4-water clusters grow with an increase in Na2SO4 concentration (until the solubility transition temperature) and then start decreasing afterward. An unusual decrease in cluster size and solution compressibility has been observed with the rise in temperature for the Na2SO4 saturated solutions below the solubility transition temperature, whereas an inverse pattern is followed thereafter. DOSY experiments have indicated different types of water cluster species in saturated solutions at different temperatures with varying self-diffusion coefficients. The effect of NaCl (5-15 wt %) on the solubility behavior of Na2SO4 at different temperatures has also been examined. The studies are important from both fundamental and industrial application points of view, for example, toward the clean separation of NaCl and Na2SO4 from the effluent streams of textile and tannery industries.

  7. Structure and bonding in some organotitanium and related compounds

    NARCIS (Netherlands)

    Zeinstra, Jabik Dominicus

    1981-01-01

    In this thesis investigations on the structure and chemical bonding in some organometallic compounds of transition metals with few d electrons are described. Structural studies involve the X-ray diffraction analyses of two titanium compounds. Theoretical studies deal with the electronic structure of

  8. Effects of ion concentration on the hydrogen bonded structure of water in the vicinity of ions in aqueous NaCl solutions

    Indian Academy of Sciences (India)

    A Nag; D Chakraborty; A Chandra

    2008-01-01

    Molecular dynamics simulations of dilute and concentrated aqueous NaCl solutions are carried out to investigate the changes of the hydrogen bonded structures in the vicinity of ions for different ion concentrations. An analysis of the hydrogen bond population in the first and second solvation shells of the ions and in the bulk water is done. Although essentially no effect of ions on the hydrogen bonding is observed beyond the first solvation shell of the ions for the dilute solutions, for the concentrated solutions a noticeable change in the average number of water-water hydrogen bonds is observed in the second solvation shells of the ions and even beyond. However, the changes in the average number of hydrogen bonds are found to be relatively less when both water-water and ion-water hydrogen bonds are counted. Thus, the changes in the total number of hydrogen bonds per water are not very dramatic beyond the first solvation shell even for concentrated solutions.

  9. Identification of Antioxidant Compounds Structure Large-Leafed Mangrove Fruit

    Directory of Open Access Journals (Sweden)

    Sabri Sudirman

    2016-08-01

    Full Text Available Antioxidants are compounds that can inhibit or prevent the oxidation of the easily oxidized substrate.One of the plants as a potential source of bioactive compounds and antioxidant activity is large-leafedmangrove (Bruguiera gymnorrhiza. This plant is commonly found in the Pacific region of Southeast Asia,Ryukyu Islands, Micronesia and Polynesia (Samoa to subtropical regions of Australia and has been usedby the society. This study aimed to determine the bioactive compounds structure of large-leafed mangrovehas the highest antioxidant activity. The compound structure prediction was done by Nuclear MagneticResonance (NMR. The compound structure in the selected antioxidant fractions are flavonol, glikosilfalvonand flavon. Those three compounds are flavonoid compound which has a great role as the one that hasantioxidant activity in large-leafed mangrove fruit.

  10. Magnetic structure of two- and three-dimensional supramolecular compounds

    Energy Technology Data Exchange (ETDEWEB)

    Decurtins, S.; Schmalle, H.W.; Pellaux, R. [Zurich Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

    1997-09-01

    Supramolecular chiral networks of oxalato-bridged transition metals show either two- or three-dimensional structural features. The magnetic structures of such compounds have been investigated by means of elastic neutron powder diffraction. (author) 2 figs., 2 refs.

  11. Magnetic structure of two- and three-dimensional supramolecular compounds

    Energy Technology Data Exchange (ETDEWEB)

    Decurtins, S.; Schmalle, H.W.; Pellaux, R. [Zurich Univ. (Switzerland); Fischer, P.; Fauth, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Ouladdiaf, B. [Institut Max von Laue - Paul Langevin, 75 - Paris (France)

    1997-09-01

    Supramolecular chiral networks of oxalato-bridged transition metals show either two- or three-dimensional structural features. The magnetic structures of such compounds have been investigated by means of elastic neutron powder diffraction. (author) 2 figs., 2 refs.

  12. Structure-Induced Covalent Bonding in Al-Li Compounds

    Science.gov (United States)

    Nozawa, Kazuki; Ishii, Yasushi

    2010-06-01

    Formation mechanism of a deep pseudogap in the electronic density of states of the Al-Li Bergman and Zintl compounds is discussed with an emphasis on the differences among isostructural Al-Mg compounds. Since Li scatters electrons very weakly in comparison with Al and Mg, the potential landscape for electrons in Al-Li compounds is not that of the entire close-packed structure but that of the Al sublattice, which is a rather porous network like the diamond lattice. The porous network structure realized by the chemical decoration of close-packed structures enhances the covalent nature of electronic structures, hence the deep pseudogap in the electronic density of states. A concept of structure-induced covalent bonding in a network realized by the chemical decoration of close-packed structures may provide a novel picture in the electronic structures of complex intermetallic compounds.

  13. Structure-Activity Relationships in Nitro-Aromatic Compounds

    Science.gov (United States)

    Vogt, R. A.; Rahman, S.; Crespo-Hernández, C. E.

    Many nitro-aromatic compounds show mutagenic and carcinogenic properties, posing a potential human health risk. Despite this potential health hazard, nitro-aromatic compounds continue to be emitted into ambient air from municipal incinerators, motor vehicles, and industrial power plants. As a result, understanding the structural and electronic factors that influence mutagenicity in nitro-aromatic compounds has been a long standing objective. Progress toward this goal has accelerated over the years, in large part due to the synergistic efforts among toxicology, computational chemistry, and statistical modeling of toxicological data. The concerted influence of several structural and electronic factors in nitro-aromatic compounds makes the development of structure-activity relationships (SARs) a paramount challenge. Mathematical models that include a regression analysis show promise in predicting the mutagenic activity of nitro-aromatic compounds as well as in prioritizing compounds for which experimental data should be pursued. A major challenge of the structure-activity models developed thus far is their failure to apply beyond a subset of nitro-aromatic compounds. Most quantitative structure-activity relationship papers point to statistics as the most important confirmation of the validity of a model. However, the experimental evidence shows the importance of the chemical knowledge in the process of generating models with reasonable applicability. This chapter will concisely summarize the structural and electronic factors that influence the mutagenicity in nitro-aromatic compounds and the recent efforts to use quantitative structure-activity relationships to predict those physicochemical properties.

  14. Predicting crystal structures of organic compounds.

    Science.gov (United States)

    Price, Sarah L

    2014-04-07

    Currently, organic crystal structure prediction (CSP) methods are based on searching for the most thermodynamically stable crystal structure, making various approximations in evaluating the crystal energy. The most stable (global minimum) structure provides a prediction of an experimental crystal structure. However, depending on the specific molecule, there may be other structures which are very close in energy. In this case, the other structures on the crystal energy landscape may be polymorphs, components of static or dynamic disorder in observed structures, or there may be no route to nucleating and growing these structures. A major reason for performing CSP studies is as a complement to solid form screening to see which alternative packings to the known polymorphs are thermodynamically feasible.

  15. Intercalation compounds involving inorganic layered structures

    Directory of Open Access Journals (Sweden)

    CONSTANTINO VERA R. L.

    2000-01-01

    Full Text Available Two-dimensional inorganic networks can shown intracrystalline reactivity, i.e., simple ions, large species as Keggin ions, organic species, coordination compounds or organometallics can be incorporated in the interlayer region. The host-guest interaction usually causes changes in their chemical, catalytic, electronic and optical properties. The isolation of materials with interesting properties and making use of soft chemistry routes have given rise the possibility of industrial and technological applications of these compounds. We have been using several synthetic approaches to intercalate porphyrins and phthalocyanines into inorganic materials: smectite clays, layered double hydroxides and layered niobates. The isolated materials have been characterized by elemental and thermal analysis, X-ray diffraction, surface area measurements, scanning electronic microscopy, electronic and resonance Raman spectroscopies and EPR. The degree of layer stacking and the charge density of the matrices as well their acid-base nature were considered in our studies on the interaction between the macrocycles and inorganic hosts.

  16. Stability regions of compounds with pyrochlore structure

    Energy Technology Data Exchange (ETDEWEB)

    Cherner, Ya.E.; Geguzina, G.A.; Fesenko, E.G. (Rostovskij-na-Donu Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Fiziki)

    1983-02-01

    Half-empirical regularities of pyrochlore type structure formation (Sm/sub 2/Zr/sub 2/O/sub 7/, Sc/sub 2/Hf/sub 2/O/sub 7/, Sm/sub 2/ScNbO/sub 7/, SrHoHfNbO/sub 7/, CdBiNbO/sub 7/ etc.) are determined and regions of its stability in terms of deformations of interatomic bonds are obtained. An analytical method of forecasting a possibility of pyrochlore type structure formation necessary for directed search of new oxides with this structure is developed using them.

  17. Diboron(4) Compounds: From Structural Curiosity to Synthetic Workhorse.

    Science.gov (United States)

    Neeve, Emily C; Geier, Stephen J; Mkhalid, Ibraheem A I; Westcott, Stephen A; Marder, Todd B

    2016-08-24

    Although known for over 90 years, only in the past two decades has the chemistry of diboron(4) compounds been extensively explored. Many interesting structural features and reaction patterns have emerged, and more importantly, these compounds now feature prominently in both metal-catalyzed and metal-free methodologies for the formation of B-C bonds and other processes.

  18. Molecular structure of diatomic lanthanide compounds

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The molecular constants of selected diatomic lanthanide compounds(LaH, LaO, LaF, EuH, EuO, EuF, EuS, GdO, GdF, GdH, YbH, YbO, YbF, YbS, LuH, LuO and LuF) have been calcu-lated by using relativistic small-core pseudopotentials and optimized(14s13p10d8f6g)/ [6s6p5d4f3g] valence basis sets. The results are in good agreement with available experimental data, with exception of YbO and LuF. The reasons for the discrepancies in case of YbO are due to a complicated mixing of configurations in the ground state, whereas in case of LuF the binding energy estimated by experimentalists appears to be too low.

  19. Molecular structure of diatomic lanthanide compounds

    Institute of Scientific and Technical Information of China (English)

    曹晓燕; 刘文剑; MichaelDolg

    2002-01-01

    The molecular constants of selected diatomic lanthanide compounds (LaH, LaO, LaF, EuH, EuO, EuF, EuS, GdO, GdF, GdH, YbH, YbO, YbF, YbS, LuH, LuO and LuF) have been calculated by using relativistic small-core pseudopotentials and optimized (14s13p10d8f6g)/ [6s6p5d4f3g] valence basis sets. The results are in good agreement with available experimental data, with exception of YbO and LuF. The reasons for the discrepancies in case of YbO are due to a complicated mixing of configurations in the ground state, whereas in case of LuF the binding energy estimated by experimentalists appears to be too low.

  20. Explosive phenomena in heavily irradiated NaCl

    NARCIS (Netherlands)

    denHartog, HW; Vainshtein, DI; Matthews, GE; Williams, RT

    1997-01-01

    In heavily irradiated NaCl crystals explosive phenomena can be initiated during irradiation or afterwards when samples are heated to temperatures between 100 and 250 degrees C. During irradiation of NaCl Na and Cl-2 precipitates and void structures are produced along with the accumulation of stored

  1. Structure and properties of intermetallic ternary rare earth compounds

    Energy Technology Data Exchange (ETDEWEB)

    Casper, Frederick

    2008-12-17

    The so called material science is an always growing field in modern research. For the development of new materials not only the experimental characterization but also theoretical calculation of the electronic structure plays an important role. A class of compounds that has attracted a great deal of attention in recent years is known as REME compounds. These compounds are often referred to with RE designating rare earth, actinide or an element from group 1-4, M representing a late transition metal from groups 8-12, and E belonging to groups 13-15. There are more than 2000 compounds with 1:1:1 stoichiometry belonging to this class of compounds and they offer a broad variety of different structure types. Although many REME compounds are know to exist, mainly only structure and magnetism has been determined for these compounds. In particular, in the field of electronic and transport properties relatively few efforts have been made. The main focus in this study is on compounds crystallizing in MgAgAs and LiGaGe structure. Both structures can only be found among 18 valence electron compounds. The f electrons are localized and therefor not count as valence electrons. A special focus here was also on the magnetoresistance effects and spintronic properties found among the REME compounds. An examination of the following compounds was made: GdAuE (E=In,Cd,Mg), GdPdSb, GdNiSb, REAuSn (RE=Gd,Er,Tm) and RENiBi (RE=Pr,Sm,Gd-Tm,Lu). The experimental results were compared with theoretic band structure calculations. The first half metallic ferromagnet with LiGaGe structure (GdPdSb) was found. All semiconducting REME compounds with MgAgAs structure show giant magnetoresistance (GMR) at low temperatures. The GMR is related to a metal-insulator transition, and the value of the GMR depends on the value of the spin-orbit coupling. Inhomogeneous DyNiBi samples show a small positive MR at low temperature that depends on the amount of metallic impurities. At higher fields the samples show a

  2. Structures and physical properties of R2TX3 compounds

    Institute of Scientific and Technical Information of China (English)

    Pan Zhi-Yan; Cao Chong-De; Bai Xiao-Jun; Song Rui-Bo; Zheng Jian-Bang; Duan Li-Bing

    2013-01-01

    Rare-earth compounds have been an attractive subject based on the unique electronic structures of the rare-earth elements.Novel ternary intermetallic compounds R2TX3 (R =rare-earth element or U,T =transition-metal element,X =Si,Ge,Ga,In) are a significant branch of this research field due to their complex and intriguing physical properties,such as magnetic order at low temperature,spin-glass behavior,Kondo effect,heavy fermion behavior,and so on.The unique physical properties of R2TX3 compounds are related to distinctive electronic structures,crystal structures,microinteraction,and external environment.Most R2TX3 compounds crystallize in AlB2-type or derived AlB2-type structures and exhibit many similar properties.This paper gives a concise review of the structures and physical properties of these compounds.Spin glass,magnetic susceptibility,resistivity,and specific heat of R2TX3 compounds are discussed.

  3. Proteoglycans: from structural compounds to signaling molecules.

    Science.gov (United States)

    Schaefer, Liliana; Schaefer, Roland M

    2010-01-01

    Our knowledge of proteoglycan biology has significantly expanded over the past decade with the discovery of a host of new members of this multifunctional family leading to their present classification into three major categories: (1) small leucine-rich proteoglycans, 2) modular proteoglycans, and 3) cell-surface proteoglycans. In addition to being structural proteins, proteoglycans play a major role in signal transduction with regulatory functions in various cellular processes. Being mostly extracellular, they are upstream of many signaling cascades and are capable of affecting intracellular phosphorylation events and modulating distinct pathways, including those driven by bone morphogenetic protein/transforming growth factor superfamily members, receptor tyrosine kinases, the insulin-like growth factor-I receptor, and Toll-like receptors. Mechanistic insights into the molecular and cellular functions of proteoglycans have revealed both the sophistication of these regulatory proteins and the challenges that remain in uncovering the entirety of their biological functions. This review aims to summarize the multiple functions of proteoglycans with special emphasis on their intricate composition and the newly described signaling events in which these molecules play a key role.

  4. Aspartate and glutamate mimetic structures in biologically active compounds.

    Science.gov (United States)

    Stefanic, Peter; Dolenc, Marija Sollner

    2004-04-01

    Glutamate and aspartate are frequently recognized as key structural elements for the biological activity of natural peptides and synthetic compounds. The acidic side-chain functionality of both the amino acids provides the basis for the ionic interaction and subsequent molecular recognition by specific receptor sites that results in the regulation of physiological or pathophysiological processes in the organism. In the development of new biologically active compounds that possess the ability to modulate these processes, compounds offering the same type of interactions are being designed. Thus, using a peptidomimetic design approach, glutamate and aspartate mimetics are incorporated into the structure of final biologically active compounds. This review covers different bioisosteric replacements of carboxylic acid alone, as well as mimetics of the whole amino acid structure. Amino acid analogs presented include those with different distances between anionic moieties, and analogs with additional functional groups that result in conformational restriction or alternative interaction sites. The article also provides an overview of different cyclic structures, including various cycloalkane, bicyclic and heterocyclic analogs, that lead to conformational restriction. Higher di- and tripeptide mimetics in which carboxylic acid functionality is incorporated into larger molecules are also reviewed. In addition to the mimetic structures presented, emphasis in this article is placed on their steric and electronic properties. These mimetics constitute a useful pool of fragments in the design of new biologically active compounds, particularly in the field of RGD mimetics and excitatory amino acid agonists and antagonists.

  5. Structural evolution of aqueous NaCl solutions dissolved in supercritical carbon dioxide under isobaric heating by mid and near infrared spectroscopy.

    Science.gov (United States)

    Oparin, R; Tassaing, T; Danten, Y; Besnard, M

    2005-03-01

    The local order in aqueous NaCl solutions diluted in supercritical carbon dioxide at constant pressure as a function of NaCl concentration and temperature has been investigated using near and mid infrared absorption spectroscopy. The near IR results have allowed us to estimate the water concentration in CO(2) rich phase, whereas the state of water aggregation in CO(2) phase was investigated using mid IR spectroscopy. The analysis of the band shape variations of the OD stretching mode of HOD led us to conclude that below 100 degrees C, water molecules dissolved in CO(2) exist only under their monomeric form, whatever the salt concentration is, whereas hydrogen-bonded species, namely, dimers start to appear at higher temperatures. Larger aggregates have a negligible concentration in the range of temperature-pressure investigated. Using near and mid infrared data, we have calculated the concentrations of water species in the CO(2) phase. Upon heating, it was found that the concentration of dimers considerably increases at the expense of the monomers and only dimers are detected in carbon dioxide at highest temperatures. Changing the salt concentration affects significantly the concentration of monomers and decreases strongly the dimers population as the solution becomes progressively saturated in salt. In the saturated solution, at 340 degrees C, the dimer concentration is at least two times smaller than in the binary water-CO(2) mixture. These findings are in qualitative agreement with existing thermodynamics data showing that addition of NaCl to the binary H(2)O-CO(2) system shifts the range of partial miscibility of water and CO(2) towards higher pressure and temperature.

  6. θ-structures of Mandarin Resultative Verb Compounds

    Directory of Open Access Journals (Sweden)

    Li, Fengqi

    2011-01-01

    Full Text Available Mandarin Resultative Verb Compounds, different from any simplex words, have complicated θ-structures, since both the verb (Vcaus and its complement (Cres have the capacity of assigning their own thematic roles. The thematic roles assigned by Vcaus form the θ-structure’s main structure, and those assigned by Cres form the embedded structure. Sometimes an entity plays a role in the main structure, and at the same time plays a role in the embedded structure. If the two roles are identical, they are “coindexed”; if they are different, they form a composite role. RVC’s θ-structure is further compounded when ambiguity occurs and when causation is taken into consideration. The ambiguity of RVCs can be attributed to the different combination of thematic roles. As for causation, the two causative roles, causer and cause, can be assigned to thematic roles according to certain constraints.

  7. Structure-Based Virtual Screening of Commercially Available Compound Libraries.

    Science.gov (United States)

    Kireev, Dmitri

    2016-01-01

    Virtual screening (VS) is an efficient hit-finding tool. Its distinctive strength is that it allows one to screen compound libraries that are not available in the lab. Moreover, structure-based (SB) VS also enables an understanding of how the hit compounds bind the protein target, thus laying ground work for the rational hit-to-lead progression. SBVS requires a very limited experimental effort and is particularly well suited for academic labs and small biotech companies that, unlike pharmaceutical companies, do not have physical access to quality small-molecule libraries. Here, we describe SBVS of commercial compound libraries for Mer kinase inhibitors. The screening protocol relies on the docking algorithm Glide complemented by a post-docking filter based on structural protein-ligand interaction fingerprints (SPLIF).

  8. Crystalline molecular complexes and compounds structures and principles

    CERN Document Server

    Herbstein, Frank H

    2005-01-01

    This book provides an account of the structure and properties of crystalline binary adducts. Such crystals are perhaps better known as molecular compounds and complexes and are estimated to make up one quarter of the world's crystals. More than 600 figures, 200 tables and 3500 references are included in the book.

  9. Exploiting structural information in patent specifications for key compound prediction.

    Science.gov (United States)

    Tyrchan, Christian; Boström, Jonas; Giordanetto, Fabrizio; Winter, Jon; Muresan, Sorel

    2012-06-25

    Patent specifications are one of many information sources needed to progress drug discovery projects. Understanding compound prior art and novelty checking, validation of biological assays, and identification of new starting points for chemical explorations are a few areas where patent analysis is an important component. Cheminformatics methods can be used to facilitate the identification of so-called key compounds in patent specifications. Such methods, relying on structural information extracted from documents by expert curation or text mining, can complement or in some cases replace the traditional manual approach of searching for clues in the text. This paper describes and compares three different methods for the automatic prediction of key compounds in patent specifications using structural information alone. For this data set, the cluster seed analysis described by Hattori et al. (Hattori, K.; Wakabayashi, H.; Tamaki, K. Predicting key example compounds in competitors' patent applications using structural information alone. J. Chem. Inf. Model.2008, 48, 135-142) is superior in terms of prediction accuracy with 26 out of 48 drugs (54%) correctly predicted from their corresponding patents. Nevertheless, the two new methods, based on frequency of R-groups (FOG) and maximum common substructure (MCS) similarity measures, show significant advantages due to their inherent ability to visualize relevant structural features. The results of the FOG method can be enhanced by manual selection of the scaffolds used in the analysis. Finally, a successful example of applying FOG analysis for designing potent ATP-competitive AXL kinase inhibitors with improved properties is described.

  10. Unusual Features of Crystal Structures of Some Simple Copper Compounds

    Science.gov (United States)

    Douglas, Bodie

    2009-01-01

    Some simple copper compounds have unusual crystal structures. Cu[subscript 3]N is cubic with N atoms at centers of octahedra formed by 6 Cu atoms. Cu[subscript 2]O (cuprite) is also cubic; O atoms are in tetrahedra formed by 4 Cu atoms. These tetrahedra are linked by sharing vertices forming two independent networks without linkages between them.…

  11. Note on Structure Parameters of Wurtzite Type Compounds

    OpenAIRE

    松原, 武生; "/マツバラ, タケオ"; "Totsuji,Chieko/Matsubara,Takeo"

    1990-01-01

    "Crystal parameters of wurtzite type crystals have been investigated based on the optimized bond orbital model which is known to give the crystal structures of some III-VI compounds as the minimum of bonding energy when bond lengths are fixed. In the case of wurtzite type structures, however, it has become clear that the effect of the change in bond lengths has to be taken into account when minimizing bonding energies."

  12. Structure Modification of an Active Azo-Compound as a Route to New Antimicrobial Compounds

    Directory of Open Access Journals (Sweden)

    Simona Concilio

    2017-05-01

    Full Text Available Some novel (phenyl-diazenylphenols 3a–g were designed and synthesized to be evaluated for their antimicrobial activity. A previously synthesized molecule, active against bacteria and fungi, was used as lead for modifications and optimization of the structure, by introduction/removal or displacement of hydroxyl groups on the azobenzene rings. The aim of this work was to evaluate the consequent changes of the antimicrobial activity and to validate the hypothesis that, for these compounds, a plausible mechanism could involve an interaction with protein receptors, rather than an interaction with membrane. All newly synthesized compounds were analyzed by 1H-NMR, DSC thermal analysis and UV-Vis spectroscopy. The in vitro minimal inhibitory concentrations (MIC of each compound was determined against Gram-positive and Gram-negative bacteria and Candida albicans. Compounds 3b and 3g showed the highest activity against S. aureus and C. albicans, with remarkable MIC values of 10 µg/mL and 3 µg/mL, respectively. Structure-activity relationship studies were capable to rationalize the effect of different substitutions on the phenyl ring of the azobenzene on antimicrobial activity.

  13. Spatial structure of compound dither in L/H transition

    Energy Technology Data Exchange (ETDEWEB)

    Toda, Shinichiro; Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Itoh, Sanae I.; Yagi, Masatoshi [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Fukuyama, Atsushi [Kyoto Univ. (Japan). Dept. of Nuclear Engineering

    2000-03-01

    To study the plasma evolution and spatial structure at the L/H transition, the double hysteresis is examined by use of the 1-dimensional transport model equations. Three mechanisms for the bipolar losses, i.e., the loss cone loss, collisional bulk viscosity loss of ions and the anomalous loss are simultaneously retained. Five-fold multiple bifurcations are found to exist at the plasma edge, similar to the previous 0-dimensional study. Double hysteresis causes a self-generated oscillation, which is attributed to the compound dither, a kind of ELMs. Spatio-temporal evolution of the compound dither is analyzed. (author)

  14. "JCE" Classroom Activity Connections: NaCl or CaCl[subscript 2], Smart Polymer Gel Tells More

    Science.gov (United States)

    Chen, Yueh-Huey; Lin, Jia-Ying; Wang, Yu-Chen; Yaung, Jing-Fun

    2010-01-01

    This classroom activity connection demonstrates the differences between the effects of NaCl (a salt of monovalent metal ions) and CaCl[subscript 2] (a salt of polyvalent metal ions) on swollen superabsorbent polymer gels. Being ionic compounds, NaCl and CaCl[subscript 2] both collapse the swollen polymer gels. The gel contracted by NaCl reswells…

  15. Crystal Structure of Three Compounds Related to Triphenylene and Tetracyanoquinodimethane

    DEFF Research Database (Denmark)

    Andresen, T.L.; Krebs, Frederik C; Larsen, M.

    1999-01-01

    The crystal structures of a charge-transfer complex of triphenylene with 1,3,5-tris(2,2-dicyanovinyl) benzene (1), a complex of 2,3,6,7,10,11-hexamethoxytriphenylene with 2,5-dichlorotetracyanoquinodimethane (2) and also 2,5-dichlorotetracyanoquinodimethane itself (3) have been determined. Compound...... 1 is triclinic, space group P (1) over bar, with a = 7.055(1), b = 11.026(2), c = 17.214(3) Angstrom. alpha = 96.59 (3), beta = 90.34(3), gamma = 91.61(3)degrees. Compound 2 is triclinic, space group P (1) over bar, with a = 12.228(2), b = 12.994(3), c = 13.702(3) Angstrom, alpha = 70.72(3), beta...... = 83.73(3), gamma = 66.06(3)degrees. Compound 3 is monoclinic, space group I2/a (C2/c), with a = 13.692(3), b = 7.7183(15), c = 16.391(3) Angstrom, beta = 99.47(3)degrees. The structures of 1 and 2 consist of mixed stacks of donors and accepters. The structures of 2 and 3 both include 1...

  16. Crystal Structures and Antimicrobial Activity of Two Phosphorus Compounds

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    One phosphorus heterocycle compound 1, C13H13N2OPS, was synthesized by the reaction of Lawesson's reagent (LR) with o-phenylene diamine. The crystal belongs to the orthorhombic system, space group P212121 with a = 5.5274(11), b = 8.1603(16), c = 28.830(6) (A), V =1300.4(4) (A)3, Z = 4, Mr= 276.28, Dc = 1.411 g/cm3, F(000) = 576,μ = 0.360 mm-1, R = 0.0259 and wR = 0.0652 for 1414 observed reflections with I > 2σ(I). While compound 2, C14H17N2O2PS, was obtained as a ring-cleavage product of compound 1. This crystal is of monoclinic system, space group P21/c with a = 9.5619(19), b = 21.879(4), c = 7.3618(15) (A), β= 103.03(3)°, V=1500.4(5) (A)3,Z = 4, Mr= 308.33, Dc = 1.365 g/cm3, F(000) = 648, μ = 0.325 mm-1, R = 0.0383 and wR =0.0742for 2283 observed reflections with I > 2σ(I). Phosphorus atom in each compound bonds with sulfur and carbon atoms using sp3 hybrid orbitals, and crystals of these two compounds are formed and stabilized by intermolecular hydrogen bonds and Van der Waals' forces. The special structure of compound 1 leads to its good antimicrobial activity against staphylococcus aureus.

  17. Structural and Electronic Investigations of Complex Intermetallic Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Hyunjin [Iowa State Univ., Ames, IA (United States)

    2008-01-01

    In solid state chemistry, numerous investigations have been attempted to address the relationships between chemical structure and physical properties. Such questions include: (1) How can we understand the driving forces of the atomic arrangements in complex solids that exhibit interesting chemical and physical properties? (2) How do different elements distribute themselves in a solid-state structure? (3) Can we develop a chemical understanding to predict the effects of valence electron concentration on the structures and magnetic ordering of systems by both experimental and theoretical means? Although these issues are relevant to various compound classes, intermetallic compounds are especially interesting and well suited for a joint experimental and theoretical effort. For intermetallic compounds, the questions listed above are difficult to answer since many of the constituent atoms simply do not crystallize in the same manner as in their separate, elemental structures. Also, theoretical studies suggest that the energy differences between various structural alternatives are small. For example, Al and Ga both belong in the same group on the Periodic Table of Elements and share many similar chemical properties. Al crystallizes in the fcc lattice with 4 atoms per unit cell and Ga crystallizes in an orthorhombic unit cell lattice with 8 atoms per unit cell, which are both fairly simple structures (Figure 1). However, when combined with Mn, which itself has a very complex cubic crystal structure with 58 atoms per unit cell, the resulting intermetallic compounds crystallize in a completely different fashion. At the 1:1 stoichiometry, MnAl forms a very simple tetragonal lattice with two atoms per primitive unit cell, while MnGa crystallizes in a complicated rhombohedral unit cell with 26 atoms within the primitive unit cell. The mechanisms influencing the arrangements of atoms in numerous crystal structures have been studied theoretically by calculating electronic

  18. Synthesis, structural and fungicidal studies of hydrazone based coordination compounds.

    Science.gov (United States)

    Sharma, Amit Kumar; Chandra, Sulekh

    2013-02-15

    The coordination compounds of the Co(II), Ni(II) and Cu(II) metal ions derived from imine based ligand, benzil bis(carbohydarzone) were structurally and pharmaceutically studied. The compounds have the general stoichiometry [M(L)]X(2) and [Co(L)X(2)], where M=Ni(II) and Cu(II), and X=NO(3)(-) and Cl(-) ions. The analytical techniques like elemental analyses, molar conductance measurements, magnetic susceptibility measurements, IR, UV/Visible, NMR, ESI mass and EPR were used to study the compounds. The key IR bands, i.e., amide I, amide II and amide III stretching vibrations accounts for the tetradentate metal binding nature of the ligand. The electronic and EPR spectral results suggest the square planar Ni(II) and Cu(II) complexes (g(iso)=2.11-2.22) and tetragonal geometry Co(II) complexes (g(iso)=2.10-2.17). To explore the compounds in the biological field, they were examined against the opportunistic pathogens, i.e., Alternaria brassicae, Aspergillus niger and Fusarium oxysporum. The partial covalent character of metal-ligand bond is supported by the orbital reduction factor k (0.62-0.92) and nephalauxetic parameter β (0.55-0.57).

  19. Crystal Structure of a Marine Natural Compound, Anhydrofusarubin

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    One marine natural compound, anhydrofusarubin, was isolated from the endophytic fungus No.B77 from the mangrove tree on the South China Sea coast.It was the first time that such a compound was isolated from marine fungus.The structure was identified by NMR data and mass spectrometry (MS).In addition, its structure was determined by single-crystal X-ray diffraction analysis.It crystallizes in triclinic, space group P1- with a = 8.3185(15), b = 12.397(2), c = 13.767(3)(A), α= 65.692(3), β= 79.266(3), γ= 75.692(3)°, C15H12O6, Mr= 288.24, V = 1248.0(4)(A)3, Z = 4, Dc = 1.534 g/cm3, F(000) = 600,/μ = 0.120 mm-1, the final R = 0.0459 and wR = 0.1184 for 5360 observed reflections (1>2σ(I)).In the primary bioassay, the title compound shows strong inhibitory activity against Gram-positive bacteria Staphyococcus aureus (ATCC27154) with the MIC value of 12.5μg/mL.

  20. New cubic structure compounds as actinide host phases

    Energy Technology Data Exchange (ETDEWEB)

    Stefanovsky, S V [SIA Radon, 7th Rostovskii lane 2/14, Moscow 119121 (Russian Federation); Yudintsev, S V; Livshits, T S, E-mail: profstef@mtu-net.ru [Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Staromonetny lane 35, Moscow 119017 (Russian Federation)

    2010-03-15

    Various compounds with fluorite (cubic zirconia) and fluorite-derived (pyrochlore, zirconolite) structures are considered as promising actinide host phases at immobilization of actinide-bearing nuclear wastes. Recently some new cubic compounds - stannate and stannate-zirconate pyrochlores, murataite and related phases, and actinide-bearing garnet structure compounds were proposed as perspective matrices for complex actinide wastes. Zirconate pyrochlore (ideally Gd{sub 2}Zr{sub 2}O{sub 7}) has excellent radiation resistance and high chemical durability but requires high temperatures (at least 1500 deg. C) to be produced by hot-pressing from sol-gel derived precursor. Partial Sn{sup 4+} substitution for Zr{sup 4+} reduces production temperature and the compounds REE{sub 2}ZrSnO{sub 7} may be hot-pressed or cold pressed and sintered at {approx}1400 deg. C. Pyrochlore, A{sub 2}B{sub 2}O{sub 7-x} (two-fold elementary fluorite unit cell), and murataite, A{sub 3}B{sub 6}C{sub 2}O{sub 20-y} (three-fold fluorite unit cell), are end-members of the polysomatic series consisting of the phases whose structures are built from alternating pyrochlore and murataite blocks (nano-sized modules) with seven- (2C/3C/2C), five- (2C/3C), eight- (3C/2C/3C) and three-fold (3C - murataite) fluorite unit cells. Actinide content in this series reduces in the row: 2C (pyrochlore) > 7C > 5C > 8C > 3C (murataite). Due to congruent melting murataite-based ceramics may be produced by melting and the firstly segregated phase at melt crystallization is that with the highest fraction of the pyrochlore modules in its structure. The melts containing up to 10 wt. % AnO{sub 2} (An = Th, U, Np, Pu) or REE/An fraction of HLW form at crystallization zoned grains composed sequentially of the 5C {yields} 8C {yields} 3C phases with the highest actinide concentration in the core and the lowest - in the rim of the grains. Radiation resistance of the 'murataite' is comparable to titanate pyrochlores. One

  1. Syntheses and Structures of Two Copper Compounds Supported by Octamolybdate

    Institute of Scientific and Technical Information of China (English)

    CHEN Shu-Mei; LU Can-Zhong; CHEN Li-Juan; MENG Ze-Rong; ZHAO Zhen-Guo

    2006-01-01

    [{Cu(phen)(DMF)2}2(β-Mo8O26)] 1 (C36H44Cu2Mo8N8O30, Mr = 1963.39, phen =1,10-phenanthroline) and [CuⅠ(phen)2]2[{CuⅠ(phen) } 2Mo8O26] 2 (C72H48Cu4Mo8N12O26, Mr = 2518.90)under solvothermal condition, respectively. Both compounds 1 and 2 are structurally characterized by elemental analyses, IR and single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system, space group P21/n, with a = 16.3347(13), b = 9.861(1), c = 17.2827(14) (A),β=99.099(4)°, V = 2748.8(3)(A)3, Z = 2, Dc = 2.372 g/cm3, F(000) = 1900 and μ = 2.614 mm-1. X-ray diffraction analysis reveals that compound 1 consists of discrete {[Cu(phen)(DMF)2]2(β-Mo8O26)}clusters constructed from β-[Mo8O26]4- subunits covalently bound to two [Cu(phen)(DMF)2]2-coordination groups. Compound 2 crystallizes in the monoclinic system, space group C2/c, with a =33.1401(9), b=16.4508(5), c=16.2622(4) (A), β=119.2460(10)°, V=7735.7(4)(A)3, Z=4, Dc=2.163 g/cm3, F(000)=4896 and μ=2.413 mm-1. X-ray diffraction analysis reveals that compound 2consists of a centrosymmetric β-octamolybdate-supported complex anion [{Cu(phen)}2Mo8O26] and two bis-phenanthroline Cu(Ⅰ) cations.

  2. NaCl Potentiates Human Fibrocyte Differentiation

    OpenAIRE

    Nehemiah Cox; Darrell Pilling; Gomer, Richard H.

    2012-01-01

    Excessive NaCl intake is associated with a variety of fibrosing diseases such as renal and cardiac fibrosis. This association has been attributed to increased blood pressure as the result of high NaCl intake. However, studies in patients with high NaCl intake and fibrosis reveal a connection between NaCl intake and fibrosis that is independent of blood pressure. We find that increasing the extracellular concentration of NaCl to levels that may occur in human blood after high-salt intake can p...

  3. Electronic Structure of Hydrogen Storage Compounds, LaNi5 and Its Micro-Hydrogenated Compounds

    Institute of Scientific and Technical Information of China (English)

    Lin Yufang; Zhao Dongliang; Wang Xinlin; Zhang Yanghuan

    2005-01-01

    The electronic structures of LaNi5 hydrogen storage alloys and its micro-hydrogenated compounds with two hydrogen atoms in the center of two octahedral interstices and two tetrahedral interstices, were investigated by the first principles discrete variational method(DVM). The results of density of states and the difference of charge distribution clearly show that the s electrons of H mainly interact with the s electrons of hydride-non-forming element Ni, despite there being a larger affinity of La for hydrogen than that of Ni in pure metal-hydrogen system. From the cohesive energy of systems, we also found two systems have almost same stability with occupation of H atoms.

  4. Investigations on organogermanium compounds XI. Preparation and structure of trialkylgermyl alkali metal compounds in hexamethylphosphoric triamide (HMPT)

    NARCIS (Netherlands)

    Bulten, E.J.; Noltes, J.G.

    1971-01-01

    In this paper a full report is given of our investigations into the preparation of trialkylgermyl alkali metal compounds. The most satisfactory route to these compounds involves the cleavage of hexaalkyldigermanes with alkali metals in HMPT at room temperature. The structure, thermal stability and

  5. Structural Characterization and Toxicity Prediction of Some Organic Compounds

    Institute of Scientific and Technical Information of China (English)

    LIAO Li-Mia; LI Jian-Feng; WANG Bi

    2011-01-01

    A new molecular structural characterization(MSC)method called molecular vertexes correlative index(MVCI)was constructed in this paper.The index was used to describe the structures of 45 compounds and a quantitative structure-activity relationship(QSAR)model of toxicity(–lgEC50)was obtained through multiple linear regression(MLR)and stepwise multiple regression(SMR).The correlation coefficient(R)of the model was 0.912,and the standard deviation(SD)of the model was 0.525.The estimation stability and prediction ability of the model were strictly analyzed by both internal and external validations.The Leave-One-Out(LOO)Cross-Validation(CV)correlation coefficient(RCV)was 0.816 and the standard deviation(SDCV)was 0.739,respectively.For the external validation,the correlation coefficient(Rtest)was 0.905 and the standard deviation(SDtest)was 0.520,respectively.The results showed that the index was superior in molecular structural representation.The stability and predictability of the model were good.

  6. Relationship structure-antioxidant activity of hindered phenolic compounds

    Directory of Open Access Journals (Sweden)

    Weng, X. C.

    2014-12-01

    Full Text Available The relationship between the structure and the antioxidant activity of 21 hindered phenolic compounds was investigated by Rancimat and DPPH· tests. 3-tert-butyl-5-methylbenzene-1,2-diol is the strongest antioxidant in the Rancimat test but not in the DPPH· test because its two hydroxyl groups have very strong steric synergy. 2,6-Ditert-butyl-4-hydroxy-methylphenol exhibits a strong antioxidant activity as 2,6-ditertbutyl- 4-methoxyphenol does in lard. 2,6-Ditert-butyl-4- hydroxy-methylphenol also exhibits stronger activity than 2-tert-butyl-4- methoxyphenol. The methylene of 2,6-ditert-butyl-4-hydroxy-methylphenol can provide a hydrogen atom to active free radicals like a phenolic hydroxyl group does because it is greatly activated by both the aromatic ring and hydroxyl group. Five factors affect the antioxidant activities of the phenolic compounds: how stable the phenolic compound free radicals are after providing hydrogen atoms; how many hy drogen atoms each of the phenolic compounds can provide; how fast the phenolic compounds provide hydrogen atoms; how easily the phenolic compound free radicals can combine with more active free radicals, and whether or not a new antioxidant can form after the phenolic compound provides hydrogen atoms.La relación entre estructura y la actividad antioxidante de 21 compuestos fenólicos con impedimentos estéricos fue investigado mediante ensayos con Rancimat y DPPH·. El 3-terc-butil-5-metilbenceno-1,2-diol es el antioxidante más potente en los ensayos mediante Rancimat pero no mediante ensayos con DPPH·, porque sus dos grupos hidroxilo tienen una fuerte sinergia estérica. El 2,6-Di-terc-butil-4-hidroxi-metil-fenol mostró una actividad antioxidante tan fuerte como el 2,6-di-ter-butil-4-metoxifenol en ensayos con manteca de cerdo. El 2,6-di-terc-butil-4-hidroxi-metilfenol también mostró una actividad más fuerte que el 2-terc-butil-4-metoxifenol. El grupo metileno del 2,6-di-ter-butil-4-hidroxi

  7. Structural and thermodynamic properties of AlB2 compound

    Institute of Scientific and Technical Information of China (English)

    Zhou Xiao-Lin; Liu Ke; Chen Xiang-Rong; Zhu Jun

    2006-01-01

    We employ a first-principles plane wave method with the relativistic analytic pseudopotential of Hartwigsen,Goedecker and Hutter (HGH) scheme in the frame of DFT to calculate the equilibrium lattice parameters and the thermodynamic properties of AlB2 compound with hcp structure. The obtained lattice parameters are in good agreement with the available experimental data and those calculated by others. Through the quasi-harmonic Dcbye model, obtained successfully are the dependences of the normalized lattice parameters a/a0 and c/c0 on pressure P, the normalized primitive cell volume V/Vo on pressure P, the variation of the thermal expansion α with pressure P and temperature T, as well as the Debye temperature θD and the heat capacity CV on pressure P and temperature T.

  8. Electronic structure and magnetism in half-Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, B R K; Dasgupta, I [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India)

    2003-11-05

    In this paper we have applied the full-potential linearized muffin tin orbital method and the tight-binding linearized muffin tin orbital method to investigate in detail the electronic structure and magnetism of a series of half-Heusler compounds XMZ with X = Fe,Co,Ni, M = Ti,V,Nb,Zr,Cr,Mo,Mn and Z Sb,Sn. Our detailed analysis of the electronic structure using various indicators of chemical bonding suggests that covalent hybridization of the higher-valent transition element X with the lower-valent transition element M is the key interaction responsible for the formation of the d-d gap in these systems. However, the presence of the sp-valent element is crucial to provide stability to these systems. The influence of the relative ordering of the atoms in the unit cell on the d-d gap is also investigated. We have also studied in detail some of these systems with more than 18 valence electrons which exhibit novel magnetic properties, namely half-metallic ferro- and ferrimagnetism. We show that the d-d gap in the paramagnetic state, the relatively large X-Sb hybridization and the large exchange splitting of the M atoms are responsible for the half-metallic property of some of these systems.

  9. Kinetics and Structure of Refractory Compounds and AlloysObtained by Mechanical Alloying

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Refractory compounds are material with interesting properties for structural applications. However, the processing of such material is a great challenge because of their high melting temperature and limited ductility. Mechanical alloying is a novel technique of producing refractory compounds with specific properties. Kinetical and structural peculiarities of refractory compounds and alloys obtained by mechanical alloying are discussed.

  10. High Pressure Strength Study on NaCl

    Science.gov (United States)

    Mi, Z.; Shieh, S. R.; High Pressure Mineral Physics Group

    2010-12-01

    Yield strength is regarded as one important property related to rheological characteristics of minerals in the Earth’s interior. The strength study of NaCl, a popular pressure medium in static high pressure experiments, has been carried out under non-hydrostatic conditions in a diamond anvil cell up to 43 GPa at room temperature using radial energy dispersive X-ray diffraction technique. Phase transformation from B1 (rock salt structure) to B2 (CsCl structure) starts at 29.4 GPa, and is complete at 32.1 GPa. Bulk modulus obtained by third order Birch-Manurgham equation of state is 25.5 GPa with pressure derivative 4.6 for B1 phase, and 30.78 GPa with pressure derivative 4.32 GPa for B2 phase, which are in a good agreement with previous studies. The differential stress of NaCl B1 phase shows very gentle increase with pressure, which indicates that NaCl is a very good pressure-transmitting medium at pressure below 30 GPa. However, the differential stress increases more abruptly for B2 phase and this may imply that NaCl can no longer be regarded as a “soft” pressure medium at very high pressures. For B1 phase, (111) is the strongest plane and (200) is the weakest plane, while (200) becomes the strongest plane in B2 phase. Pure NaCl is weaker than mixture MgO and NaCl, which indicates that soft material become stronger when mixed with hard material. The yield strength of B2 obtained through energy dispersive X-ray diffraction technique increase linearly, while the value derived by pressure gradient method shows jagged trend.

  11. Structural trends in off stoichiometric chalcopyrite type compound semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Christiane

    2011-03-15

    Energy supply is one of the most controversial topics that are currently discussed in our global community. Most of the energy delivered to the customer today has its origin in fossil and nuclear power plants. Indefinable risks and the radioactive waste repository problem of the latter as well as the global scarcity of fossil resources cause the renewable energies to grow more and more important for achieving sustainability. The main renewable energy sources are wind power, hydroelectric power and solar energy. On the photovoltaic (PV) market different materials are competing as part of different kinds of technologies, with the largest contribution still coming from wafer based crystalline silicon solar cells (95 %). Until now thin film solar cells only contribute a small portion to the whole PV market, but large capacities are under construction. Thin film photovoltaic shows a number of advantages in comparison to wafer based crystalline silicon PV. Among these material usage and production cost reduction are two prominent examples. The type of PV materials, which are analyzed in this work, are high potential compounds that are widely used as absorber layer in thin film solar cells. These are compound semiconductors of the type CuB{sup III}C{sup VI}{sub 2} (B{sup III} = In, Ga and C{sup VI} = Se, S). Several years of research have already gone into understanding the efficiency limiting factors for solar cell devices fabricated from this compound. Most of the studies concerning electronic defects are done by spectroscopic methods mostly performed using thin films from different kinds of synthesis, without any real knowledge regarding the structural origin of these defects. This work shows a systematic fundamental structural study of intrinsic point defects that are present within the material at various compositions in CuB{sup III}C{sup VI}{sub 2} compound semiconductors. The study is done on reference powder samples with well determined chemical composition and

  12. NaCl potentiates human fibrocyte differentiation.

    Science.gov (United States)

    Cox, Nehemiah; Pilling, Darrell; Gomer, Richard H

    2012-01-01

    Excessive NaCl intake is associated with a variety of fibrosing diseases such as renal and cardiac fibrosis. This association has been attributed to increased blood pressure as the result of high NaCl intake. However, studies in patients with high NaCl intake and fibrosis reveal a connection between NaCl intake and fibrosis that is independent of blood pressure. We find that increasing the extracellular concentration of NaCl to levels that may occur in human blood after high-salt intake can potentiate, in serum-free culture conditions, the differentiation of freshly-isolated human monocytes into fibroblast-like cells called fibrocytes. NaCl affects the monocytes directly during their adhesion. Potassium chloride and sodium nitrate also potentiate fibrocyte differentiation. The plasma protein Serum Amyloid P (SAP) inhibits fibrocyte differentiation. High levels of extracellular NaCl change the SAP Hill coefficient from 1.7 to 0.8, and cause a four-fold increase in the concentration of SAP needed to inhibit fibrocyte differentiation by 95%. Together, our data suggest that NaCl potentiates fibrocyte differentiation. NaCl-increased fibrocyte differentiation may thus contribute to NaCl-increased renal and cardiac fibrosis.

  13. NaCl potentiates human fibrocyte differentiation.

    Directory of Open Access Journals (Sweden)

    Nehemiah Cox

    Full Text Available Excessive NaCl intake is associated with a variety of fibrosing diseases such as renal and cardiac fibrosis. This association has been attributed to increased blood pressure as the result of high NaCl intake. However, studies in patients with high NaCl intake and fibrosis reveal a connection between NaCl intake and fibrosis that is independent of blood pressure. We find that increasing the extracellular concentration of NaCl to levels that may occur in human blood after high-salt intake can potentiate, in serum-free culture conditions, the differentiation of freshly-isolated human monocytes into fibroblast-like cells called fibrocytes. NaCl affects the monocytes directly during their adhesion. Potassium chloride and sodium nitrate also potentiate fibrocyte differentiation. The plasma protein Serum Amyloid P (SAP inhibits fibrocyte differentiation. High levels of extracellular NaCl change the SAP Hill coefficient from 1.7 to 0.8, and cause a four-fold increase in the concentration of SAP needed to inhibit fibrocyte differentiation by 95%. Together, our data suggest that NaCl potentiates fibrocyte differentiation. NaCl-increased fibrocyte differentiation may thus contribute to NaCl-increased renal and cardiac fibrosis.

  14. Kinetin Reversal of NaCl Effects

    Science.gov (United States)

    Katz, Adriana; Dehan, Klara; Itai, Chanan

    1978-01-01

    Leaf discs of Nicotiana rustica L. were floated on NaCl in the presence of kinetin or abscisic acid. On the 5th day 14CO2 fixation, [3H]leucine incorporation, stomatal conductance, and chlorophyll content were determined. Kinetin either partially or completely reversed the inhibitory effects of NaCl while ABA had no effect. PMID:16660618

  15. Dislocation structures and anomalous flow in L12 compounds

    Science.gov (United States)

    Dimiduk, D. M.

    1991-06-01

    The theory of the anomalous flow behavior of LI2 compounds has developed over the last 30 years. This theory has a foundation in the early estimates of the crystallographic anisotropy of antiphase boundary (APB) energy in these compounds. In spite of this critical aspect of the theory, it is only in the last five years that electron microscopy has been employed to quantify the APB energies and to determine the detailed nature of dislocation structures at each stage of deformation. The recent studies of several research groups have provided essentially consistent new details about the nature of dislocations in Ni3AI and a few other LI2 compounds which exhibit anomalous flow behavior. These studies have introduced several new concepts for the controlling dislocation mechanisms. Additionally, these studies have shown that in Ni3AI, the APB energies have only small variations in magnitude with change of the APB plane (they are nearly isotropic), are relatively insensitive to changes in solute content, and the anisotropy ratio does not correlate with alloy strength. The present manuscript provides a critical review of the new transmission electron microscopy (TEM) results along with the new concepts for the mechanism of anomalous flow. Inconsistencies and deficiencies within these new concepts are identified and discussed. The collective set of electron-microscopy results is discussed within the context of both the mechanical behavior of LI2 compounds and the Greenberg and Paidar, Pope and Vitek (PPV) models for anomalous flow. Conceptual consistency with these models can only be constructed if the Kear-Wilsdorf (K-W) configurations are treated as an irreversible work hardening or relaxation artifact and, specific details of these two models cannot be shown by electron microscopy. Alternatively, the structural features recently revealed by electron microscopy have not been assembled into a self-consistent model for yielding which fully addresses the mechanical behavior

  16. How do 2D fingerprints detect structurally diverse active compounds? Revealing compound subset-specific fingerprint features through systematic selection.

    Science.gov (United States)

    Heikamp, Kathrin; Bajorath, Jürgen

    2011-09-26

    In independent studies it has previously been demonstrated that two-dimensional (2D) fingerprints have scaffold hopping ability in virtual screening, although these descriptors primarily emphasize structural and/or topological resemblance of reference and database compounds. However, the mechanism by which such fingerprints enrich structurally diverse molecules in database selection sets is currently little understood. In order to address this question, similarity search calculations on 120 compound activity classes of varying structural diversity were carried out using atom environment fingerprints. Two feature selection methods, Kullback-Leibler divergence and gain ratio analysis, were applied to systematically reduce these fingerprints and generate alternative versions for searching. Gain ratio is a feature selection method from information theory that has thus far not been considered in fingerprint analysis. However, it is shown here to be an effective fingerprint feature selection approach. Following comparative feature selection and similarity searching, the compound recall characteristics of original and reduced fingerprint versions were analyzed in detail. Small sets of fingerprint features were found to distinguish subsets of active compounds from other database molecules. The compound recall of fingerprint similarity searching often resulted from a cumulative detection of distinct compound subsets by different fingerprint features, which provided a rationale for the scaffold hopping potential of these 2D fingerprints.

  17. Structure and antibacterial activity of new layered perovskite compounds

    Institute of Scientific and Technical Information of China (English)

    TAN Shao-zao; ZHANG Li-ling; XIA Liao-yuan; LIU Ying-liang; LI Du-xin

    2007-01-01

    New layered perovskite compounds, AgxNa2-xLa2Ti3O10 (x=0.2, 0.3 and 0.5) were synthesized by an ion-exchange reaction of Na2La2Ti3O10 with AgNO3 solution and characterized by energy dispersive X-ray analysis(EDX), X-ray diffractometry(XRD), scanning electron microscopy(SEM) and X-ray photoelectron spectroscopy(XPS). The ion-exchange processes were optimized, and the antibacterial activity, light permanency and water-resistance were evaluated. Surprisedly, no significant changes in crystal structure of Na2La2Ti3O10 are found by the exchange of silver ions. The Ag0.3Na1.7La2Ti3O10 particles conglomerate obviously with irregular shape and size. Ag0.3Na1.7La2Ti3O10, possessing the minimum inhibitory concentrations(MICs) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) of 180 mg/L and 240 mg/L, has high antibacterial activity, good light permanency and water-resistance. The ionic state silver in AgxNa2-xLa2Ti3O10 is the antibacterial active component.

  18. Structural Properties and Phonon dispertion of NACl

    Directory of Open Access Journals (Sweden)

    R. Khoda-Bakhsh

    2001-06-01

    Full Text Available   Although many phenomena in condensed matter Physics can be understood on the basis of a model, there are also considerable number of physical properties of solid which can not be explained except in the framework of lattice dynamics.   We have calculated the phonon frequencies of Na Cl, using an approach which is a combination of frozen phonon and force constants methods in the framework of density functional pseudopotential theory. The dispersion relation curves, were calculated along symmetry direction Δ,  Σ  and  Ù. We also calculated Grunesein parameters for all modes at X and L points in Brillion zone. The calcutions are made in the framework of density functional and pseudopotential theory, using super cell method, with the valence orbitals expanded in plane waves.

  19. Synthesis, structure and photoluminescent property of a novel potassic compound

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel 3D coordination compound of K(H2TDA)(H2O) (1) (H3TDA = 1H-1,2,3-triazole-4,5-dicarboxylic acid) has been prepared and characterized by IR spectroscopy, elemental analysis, ICP and single-crystal X-ray diffraction. Compound 1 displays strong fluorescent emission at room temperature.

  20. Constant enthalpy change value during pyrophosphate hydrolysis within the physiological limits of NaCl.

    Science.gov (United States)

    Wakai, Satoshi; Kidokoro, Shun-ichi; Masaki, Kazuo; Nakasone, Kaoru; Sambongi, Yoshihiro

    2013-10-11

    A decrease in water activity was thought to result in smaller enthalpy change values during PPi hydrolysis, indicating the importance of solvation for the reaction. However, the physiological significance of this phenomenon is unknown. Here, we combined biochemistry and calorimetry to solve this problem using NaCl, a physiologically occurring water activity-reducing reagent. The pyrophosphatase activities of extremely halophilic Haloarcula japonica, which can grow at ∼4 M NaCl, and non-halophilic Escherichia coli and Saccharomyces cerevisiae were maximal at 2.0 and 0.1 M NaCl, respectively. Thus, halophilic and non-halophilic pyrophosphatases exhibit distinct maximal activities at different NaCl concentration ranges. Upon calorimetry, the same exothermic enthalpy change of -35 kJ/mol was obtained for the halophile and non-halophiles at 1.5-4.0 and 0.1-2.0 M NaCl, respectively. These results show that solvation changes caused by up to 4.0 M NaCl (water activity of ∼0.84) do not affect the enthalpy change in PPi hydrolysis. It has been postulated that PPi is an ATP analog, having a so-called high energy phosphate bond, and that the hydrolysis of both compounds is enthalpically driven. Therefore, our results indicate that the hydrolysis of high energy phosphate compounds, which are responsible for biological energy conversion, is enthalpically driven within the physiological limits of NaCl.

  1. Constant Enthalpy Change Value during Pyrophosphate Hydrolysis within the Physiological Limits of NaCl*

    Science.gov (United States)

    Wakai, Satoshi; Kidokoro, Shun-ichi; Masaki, Kazuo; Nakasone, Kaoru; Sambongi, Yoshihiro

    2013-01-01

    A decrease in water activity was thought to result in smaller enthalpy change values during PPi hydrolysis, indicating the importance of solvation for the reaction. However, the physiological significance of this phenomenon is unknown. Here, we combined biochemistry and calorimetry to solve this problem using NaCl, a physiologically occurring water activity-reducing reagent. The pyrophosphatase activities of extremely halophilic Haloarcula japonica, which can grow at ∼4 m NaCl, and non-halophilic Escherichia coli and Saccharomyces cerevisiae were maximal at 2.0 and 0.1 m NaCl, respectively. Thus, halophilic and non-halophilic pyrophosphatases exhibit distinct maximal activities at different NaCl concentration ranges. Upon calorimetry, the same exothermic enthalpy change of −35 kJ/mol was obtained for the halophile and non-halophiles at 1.5–4.0 and 0.1–2.0 m NaCl, respectively. These results show that solvation changes caused by up to 4.0 m NaCl (water activity of ∼0.84) do not affect the enthalpy change in PPi hydrolysis. It has been postulated that PPi is an ATP analog, having a so-called high energy phosphate bond, and that the hydrolysis of both compounds is enthalpically driven. Therefore, our results indicate that the hydrolysis of high energy phosphate compounds, which are responsible for biological energy conversion, is enthalpically driven within the physiological limits of NaCl. PMID:23965994

  2. Study on the local atomic structure of germanium in organic germanium compounds by EXAFS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Organic germanium compounds have been extensively applied in medicine as tonics,In this paper,the local structures of two organic germanium compounds,carboxyethylgermanium sesquioxide and polymeric germanium glutamate,were determined by EXAFS.The structure parameters including coordination numbers and bond lengths were reported,and possible structure patterns were discussed.

  3. Structure map including off-stoichiometric and ternary sp-d-valent compounds

    Science.gov (United States)

    Hammerschmidt, T.; Bialon, A. F.; Drautz, R.

    2017-10-01

    Structure maps predict the crystal structure of a compound from the knowledge of constituent elements and chemical composition. We recently developed a highly predictive, three-dimensional structure map for stoichiometric binary sp- d-valent compounds. Here we show that the descriptors of this structure map are transferable to off-stoichiometric compounds with similar predictive power. We furthermore demonstrate that the descriptors are suitable for ternary prototypes. In particular, we construct a three-dimensional structure map for 129 prototypical crystal structures for ternary compounds. The crystal structure is predicted correctly with a probability of 78%. With a confidence of 95% the correct crystal structure is among the three most likely crystal structures predicted by the structure map.

  4. Isolation and structural elucidation of compounds from the non ...

    African Journals Online (AJOL)

    CARTA

    This study sought to isolate compounds from the non- alkaloidal extract of aerial parts of the plant and ... The material was air-dried and ground before use. Solvents, materials and reagents ... Germany) were used for recrystallization of.

  5. Systematic Assessment of Molecular Selectivity at the Level of Targets, Bioactive Compounds, and Structural Analogues.

    Science.gov (United States)

    Hu, Ye; Bajorath, Jürgen

    2016-06-20

    Through systematic mining of compound activity data, the target selectivity of bioactive compounds was systematically explored. The analysis was facilitated by applying, extending, and combining the concepts of target cliffs, selectivity cliffs, and matched molecular pairs. Selectivity relationships were explored at different levels including targets, individual bioactive compounds, and pairs of structural analogues. A variety of targets were identified for which active compounds were consistently nonselective or, by contrast, exclusively selective, making it possible to prioritize, or de-prioritize, targets for compound development. Furthermore, many chemical modifications were detected that altered compound selectivity in a well-defined manner including small structural changes that converted nonselective into target-selective compounds or inverted the target selectivity of active compounds. A large knowledge base of selectivity relationships across pharmaceutical targets and chemical modifications that alter selectivity was generated; this has been made freely available to the scientific community as a part of this investigation.

  6. Prediction of bioactive compound pathways using chemical interaction and structural information.

    Science.gov (United States)

    Cheng, Shiwen; Zhu, Changming; Chu, Chen; Huang, Tao; Kong, Xiangyin; Zhu, Liu Cun

    2016-01-01

    The functional screening of compounds is an important topic in chemistry and biomedicine that can uncover the essential properties of compounds and provide information concerning their correct use. In this study, we investigated the bioactive compounds reported in Selleckchem, which were assigned to 22 pathways. A computational method was proposed to identify the pathways of the bioactive compounds. Unlike most existing methods that only consider compound structural information, the proposed method adopted both the structural and interaction information from the compounds. The total accuracy achieved by our method was 61.79% based on jackknife analysis of a dataset of 1,832 bioactive compounds. Its performance was quite good compared with that of other machine learning algorithms (with total accuracies less than 46%). Finally, some of the false positives obtained by the method were analyzed to investigate the likelihood of compounds being annotated to new pathways.

  7. Compound library development guided by protein structure similarity clustering and natural product structure.

    Science.gov (United States)

    Koch, Marcus A; Wittenberg, Lars-Oliver; Basu, Sudipta; Jeyaraj, Duraiswamy A; Gourzoulidou, Eleni; Reinecke, Kerstin; Odermatt, Alex; Waldmann, Herbert

    2004-11-30

    To identify biologically relevant and drug-like protein ligands for medicinal chemistry and chemical biology research the grouping of proteins according to evolutionary relationships and conservation of molecular recognition is an established method. We propose to employ structure similarity clustering of the ligand-sensing cores of protein domains (PSSC) in conjunction with natural product guided compound library development as a synergistic approach for the identification of biologically prevalidated ligands with high fidelity. This is supported by the concepts that (i) in nature spatial structure is more conserved than amino acid sequence, (ii) the number of fold types characteristic for all protein domains is limited, and (iii) the underlying frameworks of natural product classes with multiple biological activities provide evolutionarily selected starting points in structural space. On the basis of domain core similarity considerations and irrespective of sequence similarity, Cdc25A phosphatase, acetylcholinesterase, and 11beta-hydroxysteroid dehydrogenases type 1 and type 2 were grouped into a similarity cluster. A 147-member compound collection derived from the naturally occurring Cdc25A inhibitor dysidiolide yielded potent and selective inhibitors of the other members of the similarity cluster with a hit rate of 2-3%. Protein structure similarity clustering may provide an experimental opportunity to identify supersites in proteins.

  8. Structural Representation of Organometallics and Coordination Compounds and a Recommended Representation by Use of Dashed Lines

    Directory of Open Access Journals (Sweden)

    Shu-Kun Lin

    2002-12-01

    Full Text Available By using broken lines to represent coordination interactions in organometallic and other coordinated compounds, we can draw structures satisfying the valencies of the atoms present. These broken lines should be used to replace many false single covalent bonds now used to depict organometallic and coordinated compounds. Chemical drawing software should not recognize such broken lines as single covalent bonds and they should be ignored. An example of confusing and erroneous structural representation of organometallics and coordination compounds is discussed.

  9. Inhibition of the compound action potentials of frog sciatic nerves by aroma oil compounds having various chemical structures.

    Science.gov (United States)

    Ohtsubo, Sena; Fujita, Tsugumi; Matsushita, Akitomo; Kumamoto, Eiichi

    2015-03-01

    Plant-derived chemicals including aroma oil compounds have an ability to inhibit nerve conduction and modulate transient receptor potential (TRP) channels. Although applying aroma oils to the skin produces a local anesthetic effect, this has not been yet examined throughly. The aim of the present study was to know how nerve conduction inhibitions by aroma oil compounds are related to their chemical structures and whether these activities are mediated by TRP activation. Compound action potentials (CAPs) were recorded from the frog sciatic nerve by using the air-gap method. Citral (aldehyde), which activates various types of TRP channels, attenuated the peak amplitude of CAP with the half-maximal inhibitory concentration (IC50) value of 0.46 mmol/L. Another aldehyde (citronellal), alcohol (citronellol, geraniol, (±)-linalool, (-)-linalool, (+)-borneol, (-)-borneol, α-terpineol), ester (geranyl acetate, linalyl acetate, bornyl acetate), and oxide (rose oxide) compounds also reduced CAP peak amplitudes (IC50: 0.50, 0.35, 0.53, 1.7, 2.0, 1.5, 2.3, 2.7, 0.51, 0.71, 0.44, and 2.6 mmol/L, respectively). On the other hand, the amplitudes were reduced by a small extent by hydrocarbons (myrcene and p-cymene) and ketone (camphor) at high concentrations (2-5 mmol/L). The activities of citral and other TRP agonists ((+)-borneol and camphor) were resistant to TRP antagonist ruthenium red. An efficacy sequence for the CAP inhibitions was generally aldehydes ≥ esters ≥ alcohols > oxides > hydrocarbons. The CAP inhibition by the aroma oil compound was not related to its octanol-water partition coefficient. It is suggested that aroma oil compounds inhibit nerve conduction in a manner specific to their chemical structures without TRP activation.

  10. Synthesis and Crystal Structure of a New Glycinato Copper Compound

    Institute of Scientific and Technical Information of China (English)

    XIANG Sheng-Chang; SHENG Tian-Lu; FU Rui-Biao; HU Sheng-Min; WU Xin-Tao

    2006-01-01

    A glycinato copper compound {Cu(NH2CH2COO)(H2O)ClO4} crystallizes in monoclinic, space group P21/n with a = 7.8299(9), b = 10.3807(10), c = 9.4775(12)(A), β = 109.659(6)°, V = 725.43(12)(A)3, Z = 4, Mr = 255.07, Dc = 2.335 g/cm3, F(000) = 508, μ = 3.381 mm-1, R = 0.0270 and wR = 0.0707 for 1677 observed reflections with I > 2σ(I). The title compound contains a chain in the syn-anti conformation, which is generated by the glide-plane operation. The adjacent layers made up of the chains through the connection of perchlorate are related by inversion center ope- ration, which links with each other through the hydrogen bonds.

  11. Low Temperature Structure and Properties of Graphite Lamellar Compounds.

    Science.gov (United States)

    1984-01-01

    macroscopic defects hinder crystallographic analyses : the lack of layer planeness (e.g., puckering of the layers) and the presence of twinned...between these two and it seams that at 300 K, the 2D melting process has already started for the three compounds. As concerns n, its value is much...free metal and that of graphite; for the others, this value is smaller than both of these. It seams then, a priori, difficult to interpret this expansion

  12. Crystal structure prediction and electronic properties of Li-based ternary compounds

    Energy Technology Data Exchange (ETDEWEB)

    Vergniory, Maia G.; Sanna, Antonio; Ernst, Arthur; Romero, Aldo H.; Gross, Eberhard K.U. [Max Planck Institute of Microstructure Physics, 06120 Halle (Germany); Marques, Miguel A.L.; Botti, Silvana; Valencia, Irais [Universite de Lyon, F-69000 Lyon, France and LPMCN, CNRS, UMR 5586, Universite Lyon 1, F-69622 Villeurbanne (France); Amsler, Max; Goedecker, Stefan [Department of Physics, Universitaet Basel, Klingelbergstr. 82, 4056 Basel (Switzerland); Chulkov, Evgueni V. [Donostia International Physics Center, 20018 Donostia-San Sebastian (Spain)

    2013-07-01

    On the basis of ab initio first principles and using the Minimal Hopping Algorithm we predict the crystal structure of non synthesized LiYZ (Y=Au,Ag, Z=Te,Se) based ternary compounds. We find that, as distinct from expectation, the crystal structure depends strongly on the composition, thus every compound belongs to a different symmetry group and has complexly different electronic properties. We analyze the fundamental physics below these features considering the calculated ground state structure.

  13. Spontaneous magnetization of aluminum nanowires deposited on the NaCl(100) surface

    OpenAIRE

    Ayuela, A.; Räbiger, H.; Puska, M. J.; Nieminen, R. M.

    2001-01-01

    We investigate electronic structures of Al quantum wires, both unsupported and supported on the (100) NaCl surface, using the density-functional theory. We confirm that unsupported nanowires, constrained to be linear, show magnetization when elongated beyond the equilibrium length. Allowing ions to relax, the wires deform to zig-zag structures with lower magnetization but no dimerization occurs. When an Al wire is deposited on the NaCl surface, a zig-zag geometry emerges again. The magnetizat...

  14. Systematically structural identification of nitric compounds in crude oil with chemometric resolution

    Institute of Scientific and Technical Information of China (English)

    HUANG Yi; ZHANG Tai-ming; LIANG Yi-zeng; CUI Hui

    2005-01-01

    Aimed at the problem of classification of non-hydrocarbons of crude oil, the theoretical standpoint that the polarity of a compound depends on the whole structure and composition of molecule instead of a kind of heteroatom or its functional group was presented. A method was established for the systematically structural identification of nitric compounds in crude oil. The pre-fractionation of a crude oil sample into 7 fractions was performed by djadsorption column chromatography with neutral aluminum oxide and silica gel. Subsequently, the individual components were obtained by using capillary column gas chromatography, and the types of compounds were detected by a mass spectrometer. In combination with a chemometric resolution, the compounds of fraction were further identified. This method can relieve the difficulty of classical analysis in identifying those species with very low contents or without being completely separated. The structures of 168 nitric compounds in a crude oil sample were determined by this method.

  15. Sodium-gold binaries: novel structures for ionic compounds from an ab initio structural search

    Science.gov (United States)

    Sarmiento-Pérez, Rafael; Cerqueira, Tiago F. T.; Valencia-Jaime, Irais; Amsler, Maximilian; Goedecker, Stefan; Botti, Silvana; Marques, Miguel A. L.; Romero, Aldo H.

    2013-11-01

    Intermetallic compounds made of alkali metals and gold have intriguing electronic and structural properties that have not been extensively explored. We perform a systematic study of the phase diagram of one binary system belonging to this family, namely NaxAu1-x, using the ab initio minima hopping structural prediction method. We discover that the most stable composition is NaAu2, in agreement with available experimental data. We also confirm the crystal structures of NaAu2 and Na2Au, that were fully characterized in experiments, and identify a candidate ground-state structure for the experimental stoichiometry NaAu. Moreover, we obtain three other stoichiometries, namely Na3Au2, Na3Au and Na5Au, that could be thermodynamically stable. We do not find any evidence for the existence of the experimentally proposed composition NaAu5. Finally, we perform phonon calculations to check the dynamical stability of all reported phases and we simulate x-ray diffraction spectra for comparison with future experimental data.

  16. Development of novel repellents using structure-activity modeling of compounds in the USDA archival database

    Science.gov (United States)

    The United States Department of Agriculture (USDA) has developed repellents and insecticides for the U.S. military since 1942. Repellency and toxicity data for over 30,000 compounds are contained within the USDA archive. Repellency data from subsets of similarly structured compounds were used to dev...

  17. Magnetic structure and phase formation of magnetocaloric Mn-Fe-P-X compounds

    NARCIS (Netherlands)

    Ou, Z.Q.

    2013-01-01

    This thesis presents a study of the crystal and magnetic structure, the magnetocaloric effect and related physical properties in Mn-Fe-P-X compounds. The influences of boron addition in (Mn,Fe)2(P,As) compounds have been studied. It is found that boron atoms occupy interstitial sites within the basa

  18. Magnetic structure and phase formation of magnetocaloric Mn-Fe-P-X compounds

    NARCIS (Netherlands)

    Ou, Z.Q.

    2013-01-01

    This thesis presents a study of the crystal and magnetic structure, the magnetocaloric effect and related physical properties in Mn-Fe-P-X compounds. The influences of boron addition in (Mn,Fe)2(P,As) compounds have been studied. It is found that boron atoms occupy interstitial sites within the

  19. Cross-Language Transfer of Insight into the Structure of Compound Words

    Science.gov (United States)

    Zhang, Jie; Anderson, Richard C.; Li, Hong; Dong, Qiong; Wu, Xinchun; Zhang, Yan

    2010-01-01

    Cross-language transfer of awareness of the structure of compound words was investigated among native speakers of Chinese who were learning English as a second language. Chinese fifth graders received instruction in the morphology of four types of compound words in either Chinese or English. They then completed both the Chinese and English…

  20. Isolation and Structure Elucidation of Autolytimycin, A New Compound Produced by Streptomyces Autolyticus JX-47

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Autolytimycin 1 was isolated from the culture filtrate ofStreptomyces autolyticus JX-47,together with two known compounds, lebstatin 2 and 17-O-demethyl-geldanamycin 3. These compounds showed the activities of anti-HSV-I. The structure of 1 was determined by spectral analysis.

  1. Cross-Language Transfer of Insight into the Structure of Compound Words

    Science.gov (United States)

    Zhang, Jie; Anderson, Richard C.; Li, Hong; Dong, Qiong; Wu, Xinchun; Zhang, Yan

    2010-01-01

    Cross-language transfer of awareness of the structure of compound words was investigated among native speakers of Chinese who were learning English as a second language. Chinese fifth graders received instruction in the morphology of four types of compound words in either Chinese or English. They then completed both the Chinese and English…

  2. Low-valent iron mono-diazadiene compounds: electronic structure and catalytic application

    NARCIS (Netherlands)

    Lichtenberg, C.; Adelhardt, M.; Gianetti, T.L.; Meyer, K.; de Bruin, B.; Grützmacher, H.

    2015-01-01

    A series of monodiazadiene diolefin iron compounds, [Fe(trop(2)dad)(L)] (4; L = neutral ligand), has been prepared by one-electron oxidation of the Fe-I species [NaFe-(trop(2)dad)(thf)(3)] (dad = diazadiene; trop = 5H-dibenzo[a,d]-cyclohepten-5-yl). The electronic structures of compounds 4 were inve

  3. Targeting apoptosis pathways by natural compounds in cancer: marine compounds as lead structures and chemical tools for cancer therapy.

    Science.gov (United States)

    von Schwarzenberg, Karin; Vollmar, Angelika M

    2013-05-28

    Natural compounds derived from marine organisms have shown a wide variety of anti-tumor effects and a lot of attention has been drawn to further development of the isolated compounds. A vast quantity of individual chemical structures from different organisms has shown a variety of apoptosis inducing mechanisms in a variety of tumor cells. The bis-steroidal cephalostatin 1 for example, induces apoptosis via activation of caspases whereas the polyketide discodermolide inhibits cell growth by binding to and stabilizing microtubule and salisporamide A, the product of an actinobacterial strain, is an inhibitor of the proteasome. This great variety of mechanisms of action can help to overcome the multitude of resistances exhibited by different tumor specimens. Products from marine organisms and their synthetic derivates are therefore an important source for new therapeutics for single agent or combined therapy with other chemotherapeutics to support the struggle against cancer.

  4. PREDICTION OF CHEMICAL REACTIVITY PARAMETERS AND PHYSICAL PROPERTIES OF ORGANIC COMPOUNDS FROM MOLECULAR STRUCTURE USING SPARC

    Science.gov (United States)

    The computer program SPARC (SPARC Performs Automated Reasoning in Chemistry) has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC uses computational algorithms...

  5. PREDICTION OF CHEMICAL REACTIVITY PARAMETERS AND PHYSICAL PROPERTIES OF ORGANIC COMPOUNDS FROM MOLECULAR STRUCTURE USING SPARC

    Science.gov (United States)

    The computer program SPARC (SPARC Performs Automated Reasoning in Chemistry) has been under development for several years to estimate physical properties and chemical reactivity parameters of organic compounds strictly from molecular structure. SPARC uses computational algorithms...

  6. Structure elucidation and antioxidant activity of the phenolic compounds from Rhynchosia suaveolens.

    Science.gov (United States)

    Rammohan, Aluru; Gunasekar, Duvvuru; Reddy, Netala Vasudeva; Vijaya, Tartte; Devillee, Alexandre; Bodo, Bernard

    2015-04-01

    A new benzophenone, 2-hydroxy-3,4-dimethoxybenzophenone (1), together with a known C-glycosylxanthone, mangiferin (2) and two known C-glycosylflavones, isovitexin (3) and isoorientin (4), were isolated from the flowers of Rhynchosia suaveolens DC. (Fabaceae). The structure of the new compound (1) and the known compounds (2-4) were elucidated by extensive 1D and 2D NMR spectral studies. The plant extracts, as well as the isolated compounds, were evaluated for their total phenolic content (TPC), total flavonoid content (TFC) and DPPH radical scavenging activity. Among the isolated compounds, mangiferin (2) and isoorientin (4) showed significant radical scavenging activity comparable with that of ascorbic acid.

  7. Rate of Homogeneous Crystal Nucleation in molten NaCl

    CERN Document Server

    Valeriani, C; Frenkel, D; 10.1063/1.1896348

    2009-01-01

    We report a numerical simulation of the rate of crystal nucleation of sodium chloride from its melt at moderate supercooling. In this regime nucleation is too slow to be studied with "brute-force" Molecular Dynamics simulations. The melting temperature of ("Tosi-Fumi") NaCl is $\\sim 1060$K. We studied crystal nucleation at $T$=800K and 825K. We observe that the critical nucleus formed during the nucleation process has the crystal structure of bulk NaCl. Interestingly, the critical nucleus is clearly faceted: the nuclei have a cubical shape. We have computed the crystal-nucleation rate using two completely different approaches, one based on an estimate of the rate of diffusive crossing of the nucleation barrier, the other based on the Forward Flux Sampling and Transition Interface Sampling (FFS-TIS) methods. We find that the two methods yield the same result to within an order of magnitude. However, when we compare the extrapolated simulation data with the only available experimental results for NaCl nucleatio...

  8. Electronic and crystal structures of thermoelectric CaMgSi intermetallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Hidetoshi, E-mail: miyazaki@nitech.ac.jp [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Inukai, Manabu [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan); Soda, Kazuo [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Miyazaki, Nobufumi; Adachi, Nozomu; Todaka, Yoshikazu [Department of Mechanical Engineering, Toyohashi University of Technology, Toyohashi 441-8580 (Japan); Nishino, Yoichi [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

    2016-01-15

    Highlights: • We report the electronic and crystal structures of the TiNiSi-type CaMgSi compound. • CaMgSi has a semiconductor-like electronic structure with a small band gap. • CaMgSi is a Mott-type insulator owing to strongly correlated electrons effect. - Abstract: We investigated the electronic and crystal structures of a new thermoelectric material, CaMgSi compound, by using synchrotron radiation photoemission spectroscopy (SR-PES), synchrotron radiation X-ray powder diffraction (SR-XRD) measurements, and electronic band structure calculation to understand the way leading to improvement in the thermoelectric properties of this material. Electronic band structure calculation of the CaMgSi compound using the crystal structure determined from SR-XRD measurement showed a semi-metallic electronic structure with a pseudo-gap at the Fermi level. In contrast to the predicted semi-metallic electronic structure, the SR-PES results showed a small semiconductor-like gap at the Fermi level. This result revealed that the CaMgSi compound is a Mott-type insulator owing to strongly correlated electrons effect in the Ca 3d and Mg 3p states being well hybridized with those in the Si 3p states. The observed electronic structure of the CaMgSi compound suggests that an optimal carrier doping exists to best control the n- and p-type thermoelectric properties and enhance the power factors.

  9. Crystal Structure and Electronic Structure of a Luminescent Compound 2-(2-Pyridyl) Benzimidazole

    Institute of Scientific and Technical Information of China (English)

    岳淑美; 苏忠民; 马建方; 廖奕; 阚玉和; 张恒君

    2003-01-01

    The crystal structure of 2-(2-pyridyl) benzimidazole was determined by singlecrystal X-ray diffraction at 193(2) K. It crystallizes in orthorhombic system, space group Pbca with unit cell constants a = 10.6204(7), b = 10.1407(4), c = 18.6327(8) A, Z= 8, V= 2006.7(2) A3, Dc. =1.292 g/cm3, F(000) = 816 andμ(MoKα) = 0.081 mm-1. The structure was refined to R = 0.0317 and wR = 0.0454 for 795 observed reflections with Ⅰ> 2σ(Ⅰ). In the solid state, it has an emission maximum at 369 nm, while in solution (DMSO), the maximum excitation is at 372 nm. Quantum chemistry calculation was performed by the method of density functional theory. Theoretical results show that atom N is the reactive site when coordinating with a metal, and the electronic structure of the title compound presents excellent carrier transport properties.

  10. Prediction of upper flammability limit percent of pure compounds from their molecular structures.

    Science.gov (United States)

    Gharagheizi, Farhad

    2009-08-15

    In this study, a quantitative structure-property relationship (QSPR) is presented to predict the upper flammability limit percent (UFLP) of pure compounds. The obtained model is a five parameters multi-linear equation. The parameters of the model are calculated only from chemical structure. The average absolute error and squared correlation coefficient of the obtained model over all 865 pure compounds used to develop the model are 9.7%, and 0.92, respectively.

  11. Synthesis and Crystal Structure of Metronidazole-derived Compound

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A MET-OH derivative, MET-OTs 1, was designed, prepared and structurally charac- terized by single-crystal X-ray diffraction. X-ray structure analysis reveals that 1 crystallizes in the monoclinic system, space group P21/c, with a = 16.1178(14), b = 7.5473(6), c = 13.4161(11) (A), V = 1520.3(2) (A)3, β = 111.3210(10)o, Z = 4, Dc = 1.421 g/cm3 and F(000) = 680.

  12. Quantitative Structure-Property Relationship Research of Main Group Compounds

    Institute of Scientific and Technical Information of China (English)

    LEI Kelin; WANG Zhendong

    2006-01-01

    New approaches were applied to improve the molecular connectivity indices mχv. The vertex valence is redefined and it was reasonable for hydrogen atom. The distances between vertices were used to propose novel connectivity topological indexes. The vertices and the distances in a molecular graph were taken into account in this definition. The linear regression was used to develop the structural property models. The results indicate that the novel connectivity topological indexes are useful model parameters for Quantitative Structure-Property Relationship(QSPR) analysis.

  13. A ring-distortion strategy to construct stereochemically complex and structurally diverse compounds from natural products

    Science.gov (United States)

    Huigens, Robert W., III; Morrison, Karen C.; Hicklin, Robert W.; Flood, Timothy A., Jr.; Richter, Michelle F.; Hergenrother, Paul J.

    2013-03-01

    High-throughput screening is the dominant method used to identify lead compounds in drug discovery. As such, the makeup of screening libraries largely dictates the biological targets that can be modulated and the therapeutics that can be developed. Unfortunately, most compound-screening collections consist principally of planar molecules with little structural or stereochemical complexity, compounds that do not offer the arrangement of chemical functionality necessary for the modulation of many drug targets. Here we describe a novel, general and facile strategy for the creation of diverse compounds with high structural and stereochemical complexity using readily available natural products as synthetic starting points. We show through the evaluation of chemical properties (which include fraction of sp3 carbons, ClogP and the number of stereogenic centres) that these compounds are significantly more complex and diverse than those in standard screening collections, and we give guidelines for the application of this strategy to any suitable natural product.

  14. Synthesis and Structure Characterization of Novel Triazole Compounds Containing 1,3-Dioxolane

    Institute of Scientific and Technical Information of China (English)

    XU Liang-zhong; JIAN Fang-fang; NIU Shu-yan; JIANG Zhi-guo

    2004-01-01

    Five novel triazole compounds containing group 1,3-dioxolane were designed and synthesized by taking difenoconazole as the start compound and changing diphenyl ether for benzyl phenyl ether. Their structures were confirmed by elemental analyses, 1H NMR and IR spectra. The single crystal structure of 2-[4-(2,4-dichlorophenylmethoxy]phenyl-2- (1,2,4-triazol-1-yl) methane-1, 3-dioxolane was determined by means of X-ray diffraction. The preliminary bioassays showed that the synthesized compounds exhibited some activities of fungicides and plant growth regulators.

  15. Solving the problem of structure determination in 3d transition metal based Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Balke, Benjamin; Fecher, Gerhard H.; Blum, Christian; Basit, Lubna; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg - University, Mainz (Germany)

    2008-07-01

    This work reports on the structural investigation of Fe-containing, Co{sub 2}-based Heusler compounds (Co{sub 2}FeZ with Z=Al, Si, Ga, Ge) using anomalous X-ray diffraction (XRD) and extended X-ray absorption fine structure spectroscopy (EXAFS). Using XRD, it was shown that Co{sub 2}FeAl crystallizes in the B2 structure whereas Co{sub 2}FeSi crystallizes in the L2{sub 1} structure. For compounds containing Ga or Ge, the XRD technique with regular laboratory sources for excitation can not be used easily to distinguish the two structures. For this reason, EXAFS was used to elucidate the structure of these two compounds. The absorption experiments close to the K-edges of Co, Fe, Ga, and Ge indicated that both compounds crystallize in the L2{sub 1} structure. Exciting the XRD at the K-edges of Co and Fe leads to anomalous X-ray scattering. The dependence of the scattering parameters on the energy close to the absorption edges was used to identify the L2{sub 1} structure of the Ga and Ge containing compounds unambiguously. The applicability of the techniques on nano-scaled materials is demonstrated for the example of Co{sub 2}FeGa nano-particles with sizes of below 25 nm.

  16. The effect of chalcogen atom on the structural, elastic, and high-pressure properties of XY compounds (X = La, Ce, Eu, and Y = S, Se, and Te): An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Charifi, Z.; Baaziz, H. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Saeed, Y. [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); Reshak, Ali Hussain [School of Complex Systems, FFWP-South Bohemia University, Nove Hrady 37333 (Czech Republic); School of Material Engineering, Malaysia University of Perlis, P.O. Box 77, d/a Pejabat Pos Besar, 01007 Kangar, Perlis (Malaysia); Soltani, F. [Physics Department, Faculty of Science, University of Batna, 05000 Batna (Algeria)

    2012-01-15

    The B1 (NaCl) and B2 (CsCl) structure of rare-earth monochalcogenides XY (X = La, Ce, Eu, and Y = S, Se, and Te) were investigated with the full-potential linearized-augmented plane wave (FP-LAPW) scheme in the frame of the generalized gradient approximation (GGA). The optimized lattice parameters, independent elastic constants (C{sub 11}, C{sub 12}, and C{sub 44}) at zero and high pressure, bulk modulus B, and its pressure derivative and the shear modulus G were evaluated. Further, the numerical estimates of a set of elastic parameters [Young's modulus E, Poisson's ratio ({nu}), Lame's coefficients ({mu}, {lambda})] of the polycrystalline XY (X = La, Ce, Eu, and Y = S, Se, and Te) compounds (in the framework of the Voigt-Reuss-Hill approximation) were performed. The pressures at which these compounds undergo structural phase transition from B1 (NaCl) to B2 (CsCl) phases were calculated. For rare-earth monochalcogenides XY, the Debye temperature is also estimated from the average sound velocity. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Electronic Structure and Geometries of Small Compound Metal Clusters

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-14

    During the tenure of the DOE grant DE-FG05-87EI145316 we have concentrated on equilibrium geometries, stability, and the electronic structure of transition metal-carbon clusters (met-cars), clusters designed to mimic the chemistry of atoms, and reactivity of homo-nuclear metal clusters and ions with various reactant molecules. It is difficult to describe all the research the authors have accomplished as they have published 38 papers. In this report, they outline briefly the salient features of their work on the following topics: (1) Designer Clusters: Building Blocks for a New Class of Solids; (2) Atomic Structure, Stability, and Electronic Properties of Metallo-Carbohedrenes; (3) Reactivity of Metal Clusters with H{sub 2} and NO; and (4) Anomalous Spectroscopy of Li{sub 4} Clusters.

  18. Electronic Structure and Geometries of Small Compound Metal Clusters

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-14

    During the tenure of the DOE grant DE-FG05-87EI145316 we have concentrated on equilibrium geometries, stability, and the electronic structure of transition metal-carbon clusters (met-cars), clusters designed to mimic the chemistry of atoms, and reactivity of homo-nuclear metal clusters and ions with various reactant molecules. It is difficult to describe all the research the authors have accomplished as they have published 38 papers. In this report, they outline briefly the salient features of their work on the following topics: (1) Designer Clusters: Building Blocks for a New Class of Solids; (2) Atomic Structure, Stability, and Electronic Properties of Metallo-Carbohedrenes; (3) Reactivity of Metal Clusters with H{sub 2} and NO; and (4) Anomalous Spectroscopy of Li{sub 4} Clusters.

  19. Vibrational spectroscopy for structural characterization of bioactive compounds

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, K.S.; Majik, M.S.; Tilvi, S.

    techniques can be taken into consideration as “green analytical technique” for the analysis of edible fats and oils [3]. Discovery of FTIR and Raman spectroscopy techniques with 4    recent innovation on Raman spectroscopy with laser as source of light... control purposed in food industries [6] and forensic sciences [7]. In the subsequent sections of the chapter, we will present the review on the basic principle of vibrational spectroscopy and their applications in the structure characterization...

  20. Alloying effect on the electronic structures of hydrogen storage compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yukawa, H.; Moringa, M.; Takahashi, Y. [Nagoya Univ. (Japan). Dept. of Mater. Sci. and Eng.

    1997-05-20

    The electronic structures of hydrogenated LaNi{sub 5} containing various 3d transition elements were investigated by the DV-X{alpha} molecular orbital method. The hydrogen atom was found to form a strong chemical bond with the Ni rather than the La atoms. The alloying modified the chemical bond strengths between atoms in a small metal octahedron containing a hydrogen atom at the center, resulting in the change in the hydrogen absorption and desorption characteristics of LaNi{sub 5} with alloying. (orig.) 7 refs.

  1. Synthesis of mesomeric betaine compounds with imidazolium-enolate structure

    Directory of Open Access Journals (Sweden)

    Nina Gonsior

    2012-03-01

    Full Text Available The synthesis of a heterocyclic mesomeric betaine by quaternization reaction of 1-butylimidazole and tetrabromo-1,4-benzoquinone is presented. The structure was verified by means of X-ray single-crystal analysis, NMR and IR spectroscopy. Inclusion complexes of the heterocyclic mesomeric betaine with randomly methylated (1.8 β-cyclodextrin were investigated by UV–vis spectroscopy. Furthermore, the reaction conditions were applied to poly(vinylimidazole and 1,4-bis(1H-imidazol-1-ylbutane to obtain functionalized polymer networks and condensate polymers, respectively.

  2. Allyl strontium compounds: synthesis, molecular structure and properties.

    Science.gov (United States)

    Jochmann, Phillip; Davin, Julien P; Maslek, Stefanie; Spaniol, Thomas P; Sarazin, Yann; Carpentier, Jean-Francois; Okuda, Jun

    2012-08-14

    The synthesis and attempted isolation of neutral bis(allyl)strontium [Sr(C(3)H(5))(2)] (1) resulted in the isolation of potassium tris(allyl)strontiate K[Sr(C(3)H(5))(3)] (2). In situ generated 1 shows a pronounced Brønsted basicity, inducing polymerisation of THF. Ate complex 2 crystallises as [K(THF)(2){Sr(C(3)H(5))(3)}(THF)](∞) (2·(THF)(3)). The salt-like solid state structure of 2·(THF)(3) comprises a two-dimensional network of (μ(2)-η(3):η(3)-C(3)H(5))(-) bridged potassium and strontium centres. Synthesis of allyl complexes 1 and 2 utilised SrI(2), [Sr(TMDS)(2)] (3) (TMDS = tetramethyldisilazanide), and [Sr(HMDS)(2)] (HMDS = hexamethyldisilazanide) as strontium precursors. The solid state structure of previously reported [Sr(TMDS)(2)] (3) was established by X-ray single crystal analysis as a dissymmetric dimer of [Sr(2)(TMDS)(4)(THF)(3)] (3·(THF)(3)) with multiple Si-HSr agostic interactions. The presence of ether ligands (THF, 18-crown-6) influenced the Si-HSr resonances in the NMR spectra of the amido complex 3.

  3. Molecular design chemical structure generation from the properties of pure organic compounds

    CERN Document Server

    Horvath, AL

    1992-01-01

    This book is a systematic presentation of the methods that have been developed for the interpretation of molecular modeling to the design of new chemicals. The main feature of the compilation is the co-ordination of the various scientific disciplines required for the generation of new compounds. The five chapters deal with such areas as structure and properties of organic compounds, relationships between structure and properties, and models for structure generation. The subject is covered in sufficient depth to provide readers with the necessary background to understand the modeling

  4. New Quantitative Structure-Activity Relationship Models Improve Predictability of Ames Mutagenicity for Aromatic Azo Compounds.

    Science.gov (United States)

    Manganelli, Serena; Benfenati, Emilio; Manganaro, Alberto; Kulkarni, Sunil; Barton-Maclaren, Tara S; Honma, Masamitsu

    2016-10-01

    Existing Quantitative Structure-Activity Relationship (QSAR) models have limited predictive capabilities for aromatic azo compounds. In this study, 2 new models were built to predict Ames mutagenicity of this class of compounds. The first one made use of descriptors based on simplified molecular input-line entry system (SMILES), calculated with the CORAL software. The second model was based on the k-nearest neighbors algorithm. The statistical quality of the predictions from single models was satisfactory. The performance further improved when the predictions from these models were combined. The prediction results from other QSAR models for mutagenicity were also evaluated. Most of the existing models were found to be good at finding toxic compounds but resulted in many false positive predictions. The 2 new models specific for this class of compounds avoid this problem thanks to a larger set of related compounds as training set and improved algorithms.

  5. Investigations on MnSb and related compounds with b8-type structures

    NARCIS (Netherlands)

    Bouwma, Jakob

    1972-01-01

    This thesis describes investigations on phases with hexagonal B8-type structures in the systems Mn-Sb-Sn, Mn-Sb-Te, Mn-Cr-Sb and Mn-V-Sb. In -chapter 1 some general remarks are made on compounds with B8-type structures. The preparation of the samples, and the X-ray crystallographic investigations

  6. Discovery of structurally diverse and bioactive compounds from plant resources in China

    Institute of Scientific and Technical Information of China (English)

    Sheng-ping YANG; Jian-min YUE

    2012-01-01

    This review describes the major discoveries of structurally diverse and/or biologically significant compounds from plant resources in China,mainly from the traditional Chinese medicines (TCMs) since the establishment of our research group in 1999.In the past decade,a large array of biologically significant and novel structures has been identified from plant resources (or TCM) in our laboratory.The structural modification of several biologically important compounds led to more than 400 derivatives,some of which exhibited significantly improved activities and provided opportunities to elucidate the structure-activity relationship of the related compound class.These findings are important for drug discovery and help us understand the biological basis for the traditional applications of these plants in TCM.

  7. High Curie temperature of Ce-Fe-Si compounds with ThMn12 structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, C; Pinkerton, FE; Herbst, JF

    2015-01-15

    We report the discovery of ternary CeFe(12-x)Si(x)compounds possessing the ThMn12 structure. The samples were prepared by melt spinning followed by annealing. In contrast to other known Ce Fe-based binary and ternary compounds, CeFe12-xSix compounds exhibit exceptionally high Curie temperatures whose values increase with added Si substitution. The highest T. = 583 K in CeFe10Si2 rivals that of the well-established Nd2Fe14B compound. We ascribe the T-c behavior to a combination of Si-induced 3d band structure changes and partial Ce3+ stabilization. (C) 2014 Published by Elsevier Ltd.

  8. ELECTRONIC STRUCTURE OF THE LaNi5-xGax INTERMETALLIC COMPOUNDS

    Institute of Scientific and Technical Information of China (English)

    D.Chen; G.X.Li; D.L.Zhang; T.Gao

    2008-01-01

    The equilibrium structures and electronic structure of LaNii5-xGax (x=0, 0.5, 1.0)compounds have been investigated by all-electron calculations. Based on the full geometry optimization, the densities of states and electron densities of LaNi5-x Gax are plotted and analyzed. It is clear that the substitution of Ga at the Ni site leads to a progressive filling of the Ni-d bands, the ionic interaction between Ni and Ni, with Ga plays a dominant role in the stability of LaNi5-x Gax compounds. The smaller the shift of EF toward higher energy region, the more stable the compounds will be.The increased contribution of the Ni-d-Ga-d interactions near EF and the low energy metal-gallium bonding bands indicate that the compounds become more stable. The results are compared with experimental data and discussed in light of previous studies.

  9. Synthesis, structural and electrochemical characterization of benzimidazole compounds exhibiting a smectic C liquid crystal phase

    Science.gov (United States)

    Wei, Bingzhuo; Tan, Shuai; Liang, Ting; Cao, Siyu; Wu, Yong

    2017-04-01

    Mesomorphic benzimidazole compounds were prepared from a biphenyl benzoate based precursor by substitution reaction of alkyl bromide with 2-mercaptobenzimidazole. Molecular structures of the benzimidazole compounds were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. Differential scanning calorimetry (DSC) measurements and polarizing optical microscopic (POM) observations revealed that the benzimidazole compounds exhibited a thermotropic smectic C (SC) phase. Temperature dependent X-ray diffraction (XRD) patterns suggested a tilted bilayer smectic structure in which intermolecular hydrogen bonds between benzimidazole moieties formed lamellar arrangement. Electrochemical impedance spectroscopy (EIS) characterization suggested that the SC phase favored anhydrous proton conduction of the benzimidazole compounds and the proton conductivities showed an Arrhenius temperature dependence.

  10. Synthesis and Structural Studies of Calcium and Magnesium Phosphinate and Phosphonate Compounds

    Science.gov (United States)

    Bampoh, Victoria Naa Kwale

    The work presented herein describes synthetic methodologies leading to the design of a wide array of magnesium and calcium based phosphinate and phosphonates with possible applications as bone scaffolding materials or additives to bone cements. The challenge to the chemistry of the alkaline earth phosphonate target compounds includes poor solubility of compounds, and poorly understood details on the control of the metal's coordination environment. Hence, less is known on phosphonate based alkaline earth metal organic frameworks as compared to transition metal phosphonates. Factors governing the challenges in obtaining crystalline, well-defined magnesium and calcium solids lie in the large metal diameters, the absence of energetically available d-orbitals to direct metal geometry, as well as the overall weakness of the metal-ligand bonds. A significant part of this project was concerned with the development of suitable reaction conditions to obtain X-ray quality crystals of the reaction products to allow for structural elucidation of the novel compounds. Various methodologies to aid in crystal growth including hydrothermal methods and gel crystallization were employed. We have used phosphinate and phosphonate ligands with different number of phosphorus oxygen atoms as well as diphosphonates with different linker lengths to determine their effects on the overall structural features. An interesting correlation is observed between the dimensionality of products and the increasing number of donor oxygen atoms in the ligands as we progress from phosphinic acid to the phosphorous acids. As an example, monophosphinate ligand only yielded one-dimensional compounds, whereas the phosphonates crystallize as one and two-dimensional compounds, and the di- and triphosphonate based compounds display two or three-dimensional geometries. This thesis provides a selection of calcium and magnesium compounds with one-dimensional geometry, as represented in a calcium phosphinate to novel

  11. Electronic Structures of Square Planar Coordinated Transition Metal Ions in Compounds with Gillespite Structure

    Institute of Scientific and Technical Information of China (English)

    林传易

    1990-01-01

    Electronic structures of square planar coordinated transition metal ions in BaCuSi4O10 and CaCrSi4O10 are investigated using the ligand-field theory(LFT),angular overlap model(AOM) and iterative extended Hueckel molecular orbital theory(IET).The electronic energy levels of the natural mineral dioptase are also investigated,in which the Cu2+ ions occupy the sites of pseudo D4h symmetry,Both LFT and AOM predict that the crystal-field levels of transition metal ions in these compounds follow such an order that E(2B1g)

  12. SARANEA: a freely available program to mine structure-activity and structure-selectivity relationship information in compound data sets.

    Science.gov (United States)

    Lounkine, Eugen; Wawer, Mathias; Wassermann, Anne Mai; Bajorath, Jürgen

    2010-01-01

    We introduce SARANEA, an open-source Java application for interactive exploration of structure-activity relationship (SAR) and structure-selectivity relationship (SSR) information in compound sets of any source. SARANEA integrates various SAR and SSR analysis functions and utilizes a network-like similarity graph data structure for visualization. The program enables the systematic detection of activity and selectivity cliffs and corresponding key compounds across multiple targets. Advanced SAR analysis functions implemented in SARANEA include, among others, layered chemical neighborhood graphs, cliff indices, selectivity trees, editing functions for molecular networks and pathways, bioactivity summaries of key compounds, and markers for bioactive compounds having potential side effects. We report the application of SARANEA to identify SAR and SSR determinants in different sets of serine protease inhibitors. It is found that key compounds can influence SARs and SSRs in rather different ways. Such compounds and their SAR/SSR characteristics can be systematically identified and explored using SARANEA. The program and source code are made freely available under the GNU General Public License.

  13. Structure-based Drug Screening and Ligand-Based Drug Screening Toward Protein-Compound Network

    Science.gov (United States)

    Fukunishi, Yoshifumi

    2007-12-01

    We developed two new methods to improve the accuracy of molecular interaction data using a protein-compound affinity matrix calculated by a protein-compound docking software. One method is a structure-based in silico drug screening method and another method is a ligand-based in silico drug screening method. These methods were applied to enhance the database enrichment of in silico drug screening and in silico target protein screening.

  14. A novel synthetic route to freely adjust the crystal structures of Ni-P compounds

    Science.gov (United States)

    Xu, Hanghui; Lu, Shaoxiang; Ren, Lili

    2016-10-01

    Crystal-structure-controllable Ni-P compounds were synthesized using nickel chloride, nontoxic red phosphorus and polyethylene glycol. The hexagonal Ni2P and tetragonal Ni12P5 could be freely transformed via adjusting the amount of polyethylene glycol, and the mechanism of phase transformation was discussed. The catalytic performances of Ni-P compounds were promoted markedly with moderate quantity of PEG. However, excessive PEG will cover the active sites of catalysts and decrease the catalytic activity.

  15. Electronic structure and magnetic properties of selected UTX compounds: LDA +U approach

    Energy Technology Data Exchange (ETDEWEB)

    Rusz, Jan; Divis, Martin [Department of Electronic Structures, Charles University, Ke Karlovu 5, 121 16 Prague 2 (Czech Republic)

    2004-09-22

    We present calculations of a set of UTX compounds (where T is a transition metal and X is a p element) in the framework of density functional theory applying the LSDA +U exchange-correlation energy functional. As the parameters U and J for these compounds are not known, we varied them in effort to reproduce experimental uranium magnetic moments. Using the obtained electronic structures we discuss the magnetism and the effects of hybridization. Our results are in improved agreement with experimental findings.

  16. Isolation, Purification, and Structural Identification of an Antifungal Compound from a Trichoderma Strain.

    Science.gov (United States)

    Li, Chong-Wei; Song, Rui-Qing; Yang, Li-Bin; Deng, Xun

    2015-08-01

    Trichoderma strain T-33 has been demonstrated to have inhibitory effect on the fungus species Cytospora chrysosperma. Here, an active antifungal compound was obtained from Trichoderma strain T-33 extract via combined separation technologies, including organic solvent extraction, liquid chromatography, and thin-layer chromatography. The purified compound was further characterized by advanced analytical technologies to elucidate its chemical structure. Results indicated that the active antifungal compound in Trichoderma strain T-33 extract is 2,5- cyclohexadiene-1,4-dione-2,6-bis (1,1-dimethylethyl).

  17. Comparative Study on the Structures of Chinese and Korean Compound Words

    Directory of Open Access Journals (Sweden)

    Zhai Xun

    2016-05-01

    Full Text Available The goal of the research was to compare the compound words in Chinese, an isolated language, and Korean, an agglutinative language. This research used library research. The researchers found that the main characteristics of the formation of Korean compound words were that the latter element was the central word. The method of word formation decided its lexical category. Moreover, most of the internal relationships of the compound words were connection and modification. While in Chinese, the endocentric compound noun decided the part of speech of the compound word, and could be the proceeding element or the latter element. Furthermore, Chinese contained no complicated morphological changes. It is concluded that Korean is a Subject–Object–Verb (SOV language, where verb elements demonstrate a central feature of the compound verb are always a trailing part. Thus, there is no exocentric compound verb in Korean. By contrast, Chinese is a typical SVO language. When constituting the compound verbs, nouns or adjectives can function as the structural elements. Therefore, there is no permanent position for head words.

  18. A structural and vibrational study of the chromyl chlorosulfate, fluorosulfate, and nitrate compounds

    CERN Document Server

    Brandán, Silvia A

    2014-01-01

    A Structural and Vibrational Study of the Chromyl Chlorosulfate, Fluorosulfate and Nitrate Compounds presents important studies related to the structural and vibrational properties on the chromyl compounds based on Ab-initio calculations. The synthesis and the study of such properties are of chemical importance because the stereo-chemistries and reactivities of these compounds are strongly dependent on the coordination modes that adopt the different ligands linked to the chromyl group. In this book, the geometries of all stable structures in gas phase for chromyl chlorosulfate, fluorosulfate, and nitrate are optimized by using Density functional Theory (DFT). Then, the complete assignments of all observed bands in the infrared and Raman spectra are performed combining DFT calculations with Pulay´s Scaled Quantum Mechanics Force Field (SQMFF) methodology and taking into account the type of coordination adopted by the chlorosulfate, fluorosulfate and nitrate ligands as monodentate and bidentate. Moreover, the ...

  19. Structure elucidation, DNA binding specificity and antiproliferative proficiency of isolated compounds from Garcinia nervosa.

    Science.gov (United States)

    Parveen, Mehtab; Azaz, Shaista; Zafar, Atif; Ahmad, Faheem; Silva, Manuela Ramos; Silva, Pedro Sidonio Pereira

    2017-02-01

    Garcinia nervosa is an abundant source of bioactive phytochemicals. The present paper deals with the isolation of a novel isoflavone 5,7-dihydroxy-3-(3'-hydroxy-4',5'-dimethoxyphenyl)-6-methoxy-4H-chromen-4-one (1) along with a known compound DL-Allantoin (2) from the ethanolic extract of the leaves of Garcinia nervosa (Family: Guttiferae). Their structures were elucidated on the basis of chemical and physical evidences viz. elemental analysis, UV, FT-IR, (1)H NMR, (13)C NMR and mass spectral analysis. Single-crystal X-ray analysis was further used for the authentication of structure of both compounds (1 and 2). Interaction studies of compound (1) and (2) with ctDNA were studied by UV-Visible spectroscopy, fluorescence, KI quenching studies, competitive displacement assay and circular dichroism studies, which showed groove binding interaction (non-intercalation) of both the compounds 1 and 2 with ctDNA. However, compound 1 (K=3.9×10(4)M(-1)) shows higher binding affinity to the ctDNA than compound 2 (K=1.44×10(4)M(-1)). The molecular modeling results also illustrated that compound 1 strongly binds to groove of DNA by relative binding energy of docked structure -6.82kcal/mol. In addition the antiproliferative activity also showed high potential of compound 1 against MCF-7 and MDA-MB 231 cell line with IC50 value 8.44±3.5μM and 6.94±2.6μM, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Ab initio determination of dark structures in radiationless transitions for aromatic carbonyl compounds.

    Science.gov (United States)

    Fang, Wei-Hai

    2008-03-01

    Mechanistic photodissociation of a polyatomic molecule has long been regarded as an intellectually challenging area of chemical physics, the results of which are relevant to atmospheric chemistry, biological systems, and many application fields. Carbonyl compounds play a unique role in the development of our understanding of the spectroscopy, photochemistry, and photophysics of polyatomic molecules and their photodissociation has been the subject of numerous studies over many decades. Upon irradiation, a molecule can undergo internal conversion (IC) and intersystem crossing (ISC) processes, besides photochemical and other photophysical processes. Transient intermediates formed in the IC and ISC radiationless processes, which are termed "dark", are not amenable to detection by conventional light absorption or emission. However, these dark intermediates play critical roles in IC and ISC processes and thus are essential to understanding mechanistic photochemistry of a polyatomic molecule. We have applied the multiconfiguration complete active space self-consistent field (CASSCF) method to determine the dark transient structures involved in radiationless processes for acetophenone and the related aromatic carbonyl compounds. The electronic and geometric structures predicted for the dark states are in a good agreement with those determined by ultrafast electron diffraction experiments. Intersection structure of different electronic states provides a very efficient "funnel" for the IC or ISC process. However, experimental determination of the intersection structure involved in radiationless transitions of a polyatomic molecule is impossible at present. We have discovered a minimum energy crossing point among the three potential energy surfaces (S1, T1, and T2) that appears to be common to a wide variety of aromatic carbonyl compounds with a constant structure. This new type of crossing point holds the key to understanding much about radiationless processes after

  1. Structural and magnetic properties of Dy2Co17-xMnx compounds

    Institute of Scientific and Technical Information of China (English)

    李云宝; 张立刚; 张绍英; 沈保根

    2002-01-01

    Using x-ray diffraction and magnetic measurements, we have studied the structural and magnetic properties ofDy2Co17-xMnx (x=0~5) compounds with a rhombohedral Th2Zn17-type structure. With an increasing Mn concen-tration x, the unit-cell volume V was found to increase linearly. The Curie temperature TC decreases linearly, andthe saturation magnetization Ms at 5K first increases slightly for x <1, then decreases rapidly for x >1 with a furtherincrease of Mn concentration x. In compounds for x=1~3, a spin reorientation was found. A magnetic diagram of thecompounds is given.

  2. A Structural Analysis of Spiropyran and Spirooxazine Compounds and Their Polymorphs

    Directory of Open Access Journals (Sweden)

    Vanessa Kristina Seiler

    2017-03-01

    Full Text Available In this work, crystal structures of commercially available photochromic compounds, i.e., spiropyrans and spirooxazines, were investigated by single-crystal X-ray diffraction. A total of five new structures were obtained via isothermal evaporation experiments under different conditions, namely 1,3,3-Trimethylindolino-benzopyrylospiran (I, 1,3,3-Trimethylindolinonaphtospirooxaxine (II, 1-(2-Hydroxyethyl-3,3-dimethylindolino-6′-nitrobenzopyrylospiran (III, and 1,3,3-Trimethylindolino-8′-methoxybenzopyrylospiran (IVa and IVb. Since the basic structure of a spiropyran/-oxazine does not present typical hydrogen bond accepting and donating groups, this study illustrates the importance of additional functional groups connected to this kind of molecules to induce specific intermolecular interactions. Our results show that possible hydrogen bonding interactions are rather weak due to the high steric demand of these compounds. These results are supported by a search of the Cambridge structural database focused on related structures.

  3. Structure elucidation and DNA binding specificity of natural compounds from Cassia siamea leaves: A biophysical approach.

    Science.gov (United States)

    Parveen, Mehtab; Ahmad, Faheem; Malla, Ali Mohammed; Khan, Mohd Sohrab; Rehman, Sayeed Ur; Tabish, Mohammad; Silva, Manuela Ramos; Silva, P S Pereira

    2016-06-01

    A novel isoflavone, 5,6,7-trimethoxy-3-(3',4',5'-trimethoxyphenyl)-4H-chromen-4-one (1) along with a known pyranocoumarin, Seselin (2) have been isolated from the ethanolic extract of the leaves of Cassia siamea (Family: Fabaceae). Compound 1 has been reported for the first time from any natural source and has not been synthesized so far. Their structures were elucidated on the basis of chemical and physical evidences viz. elemental analysis, UV, FT-IR, (1)H-NMR, (13)C-NMR and mass spectral analysis. Structure of compound (1) was further authenticated by single-crystal X-ray analysis and density functional theory (DFT) calculations. A multi-technique approach employing UV-Visible spectroscopy, fluorescence, KI quenching studies, competitive displacement assay, circular dichroism and viscosity studies have been utilized to probe the extent of interaction and possible binding modes of isolated compounds (1-2) with calf thymus DNA (CT-DNA). Both the compounds were found to interact with DNA via non-intercalative binding mode with moderate proficiencies. Groove binding was the major interaction mode in the case of compound 2 while compound 1 probably interacts with DNA through electrostatic interactions. These studies provide deeper insight in understanding of DNA-drug (natural products) interaction which could be helpful to improve their bioavailability for therapeutic purposes. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. MnFe(PGe) compounds: Preparation, structural evolution, and magnetocaloric effects

    Science.gov (United States)

    Yue, Ming; Zhang, Hong-Guo; Liu, Dan-Min; Zhang, Jiu-Xing

    2015-01-01

    The interdependences of preparation conditions, magnetic and crystal structures, and magnetocaloric effects (MCE) of the MnFePGe-based compounds are reviewed. Based upon those findings, a new method for the evaluation of the MCE in these compounds, based on differential scanning calorimetry (DSC), is proposed. The MnFePGe-based compounds are a group of magnetic refrigerants with giant magnetocaloric effect (GMCE), and as such, have drawn tremendous attention, especially due to their many advantages for practical applications. Structural evolution and phase transformation in the compounds as functions of temperature, pressure, and magnetic field are reported. Influences of preparation conditions upon the homogeneity of the compounds’ chemical composition and microstructure, both of which play a key role in the MCE and thermal hysteresis of the compounds, are introduced. Lastly, the origin of the “virgin effect” in the MnFePGe-based compounds is discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 51171003, 51071007, and 51401002).

  5. Preparation and structural characterization of corn starch-aroma compound inclusion complexes.

    Science.gov (United States)

    Zhang, Shu; Zhou, Yibin; Jin, Shanshan; Meng, Xin; Yang, Liping; Wang, Haisong

    2017-01-01

    Six corn starch inclusion complexes were synthesized using small nonpolar or weak polar aroma compounds (heptanolide, carvone and menthone) and small polar aroma compounds (linalool, heptanol and menthol). The objectives of this study were to (a) investigate the ability of corn starch to form inclusion complexes with these aroma compounds and (b) characterize the structure of the corn starch inclusion complexes. The resulting inclusion ratios were 75.6, 36.9, 43.8, 91.9, 67.2 and 54.7% for heptanolide, carvone, menthone, linalool, heptanol and menthol respectively. The inclusion complexes had laminated structures with a certain amount of holes or blocky constructions. Compared with gelatinized corn starch, the transition temperatures, peak temperatures and enthalpies of the inclusion complexes were significantly different. The major peak of CO at 1771 cm(-1) and significant peak shifts revealed the formation of inclusion complexes. X-ray diffractometry (XRD) analyses revealed that the crystallinity of corn starch-polar aroma compound inclusion complexes increased. Based on cross-polarization magic angle spinning (13) C nuclear magnetic resonance (CP-MAS (13) C NMR) results, novel peaks and chemical shifts were attributed to the presence of small aroma compounds, thereby confirming the formation of corn starch inclusion complexes. Small nonpolar and polar aroma compounds can be complexed to corn starch. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  6. Structural Elucidation and Molecular Docking of a Novel Antibiotic Compound from Cyanobacterium Nostoc sp. MGL001

    Science.gov (United States)

    Niveshika; Verma, Ekta; Mishra, Arun K.; Singh, Angad K.; Singh, Vinay K.

    2016-01-01

    Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Further characterization was done using electrospray ionization mass spectroscopy (ESIMS) and nuclear magnetic resonance (NMR) and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy) -5, 8, 13, 16–tetraaza–hexacene - 2, 3 dicarboxylic acid (EMTAHDCA). Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T, and 1LC4) and OmpF porin protein (4GCP, 4GCQ, and 4GCS) which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs. PMID:27965634

  7. Structural elucidation and molecular docking of a novel antibiotic compound from cyanobacterium Nostoc sp. MGL001

    Directory of Open Access Journals (Sweden)

    Niveshika No Name

    2016-11-01

    Full Text Available Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC and high performance liquid chromatography (HPLC. Further characterization was done using electrospray ionisation mass spectroscopy (ESIMS and nuclear magnetic resonance (NMR and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy -5, 8, 13, 16 – tetraaza – hexacene - 2, 3 dicarboxylic acid (EMTAHDCA. Structure of EMTAHDCA clearly indicated that it is a novel compound that was not reported in literature or natural product database. The compound exhibited growth inhibiting effects mainly against the gram negative bacterial strains and produced maximum zone of inhibition at 150 μg/mL concentration. The compound was evaluated through in silico studies for its ability to bind 30S ribosomal fragment (PDB ID: 1YRJ, 1MWL, 1J7T and 1LC4 and OmpF porin protein (4GCP, 4GCQ and 4GCS which are the common targets of various antibiotic drugs. Comparative molecular docking study revealed that EMTAHDCA has strong binding affinity for these selected targets in comparison to a number of most commonly used antibiotics. The ability of EMTAHDCA to bind the active sites on the proteins and 30S ribosomal fragments where the antibiotic drugs generally bind indicated that it is functionally similar to the commercially available drugs.

  8. Predicting reaction rate constants of ozone with organic compounds from radical structures

    Science.gov (United States)

    Yu, Xinliang; Yi, Bing; Wang, Xueye; Chen, Jianfang

    2012-05-01

    The reaction rate constants of ozone with organic compounds in the atmosphere were predicted by a quantitative structure-activity relationship (QSAR) model. Density functional theory (DFT) calculations, for the first time, were carried out on the radicals from organic compounds, at the UB3LYP level of theory with 6-31G(d) basis set. A set of quantum chemical descriptors calculated from the radicals, the energy of the highest occupied molecular orbital of beta spin states (EβHOMO), the molecular average polarizability (α), and the total energy (ET), were used to build the general QSAR model for aliphatic compounds, applying the genetic algorithm (GA) technique and support vector machine (SVM) regression. The root mean square errors (RMSE) are 0.680 for the training set (68 compounds), 0.777 for the validation set (36 compounds) and 0.709 for the test set (35 compounds). Investigated results indicate that the SVM model given here has good predictivity for aliphatic compounds.

  9. Structural instability and ground state of the U{sub 2}Mo compound

    Energy Technology Data Exchange (ETDEWEB)

    Losada, E.L., E-mail: losada@cab.cnea.gov.ar [SIM" 3, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (Argentina); Garcés, J.E. [Gerencia de Investigación y Aplicaciones Nucleares, Comisión Nacional de Energía Atómica (Argentina)

    2015-11-15

    This work reports on the structural instability at T = 0 °K of the U{sub 2}Mo compound in the C11{sub b} structure under the distortion related to the C{sub 66} elastic constant. The electronic properties of U{sub 2}Mo such as density of states (DOS), bands and Fermi surface (FS) are studied to understand the source of the instability. The C11{sub b} structure can be interpreted as formed by parallel linear chains along the z-directions each one composed of successive U–Mo–U blocks. Hybridization due to electronic interactions inside the U–Mo–U blocks is slightly modified under the D{sub 6} distortion. The change in distance between chains modifies the U–U interaction and produces a split of f-states. The distorted structure is stabilized by a decrease in energy of the hybridized states, mainly between d-Mo and f-U states, together with the f-band split. Consequently, an induced Peierls distortion is produced in U{sub 2}Mo due to the D{sub 6} distortion. It is important to note that the results of this work indicate that the structure of the ground state of the U{sub 2}Mo compound is not the assumed C11{sub b} structure. It is suggested for the ground state a structure with hexagonal symmetry (P6 #168), ∼0.1 mRy below the energy of the recently proposed Pmmn structure. - Highlights: • Structural instability of the C11b compound due to the D6 deformation. • Induced Peierls distortion due to the D6 deformation. • Distorted structure is stabilized by hybridization and split of f-Uranium state. • P6 (#168) suggested ground state for the U{sub 2}Mo compound.

  10. The phenolic compounds of olive oil: structure, biological activity and beneficial effects on human health.

    Science.gov (United States)

    Tripoli, Elisa; Giammanco, Marco; Tabacchi, Garden; Di Majo, Danila; Giammanco, Santo; La Guardia, Maurizio

    2005-06-01

    The Mediterranean diet is rich in vegetables, cereals, fruit, fish, milk, wine and olive oil and has salutary biological functions. Epidemiological studies have shown a lower incidence of atherosclerosis, cardiovascular diseases and certain kinds of cancer in the Mediterranean area. Olive oil is the main source of fat, and the Mediterranean diet's healthy effects can in particular be attributed not only to the high relationship between unsaturated and saturated fatty acids in olive oil but also to the antioxidant property of its phenolic compounds. The main phenolic compounds, hydroxytyrosol and oleuropein, which give extra-virgin olive oil its bitter, pungent taste, have powerful antioxidant activity both in vivo and in vitro. The present review focuses on recent works analysing the relationship between the structure of olive oil polyphenolic compounds and their antioxidant activity. These compounds' possible beneficial effects are due to their antioxidant activity, which is related to the development of atherosclerosis and cancer, and to anti-inflammatory and antimicrobial activity.

  11. Preparation and Structural Investigation of CuCl2 Graphite Intercalation Compounds

    Institute of Scientific and Technical Information of China (English)

    BIN Xiaopei; CHEN Jiazang; CAO Hong; MA Enbao; WANG Xuehua; YUAN Jizhu

    2008-01-01

    Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets.Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in thenano-scale CuCl2 graphite intercalation compounds are described. The results show that the contentof CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.

  12. Fragmentation pathways and structural characterization of 14 nerve agent compounds by electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Housman, Kathleen J; Swift, Austin T; Oyler, Jonathan M

    2015-03-01

    Organophosphate nerve agents (OPNAs) are some of the most widely used and proliferated chemical warfare agents. As evidenced by recent events in Syria, these compounds remain a serious military and terrorist threat to human health because of their toxicity and the ease with which they can be used, produced and stored. There are over 2,000 known, scheduled compounds derived from common parent structures with many more possible. To address medical, forensic, attribution, remediation and other requirements, laboratory systems have been established to provide the capability to analyze 'unknown' samples for the presence of these compounds. Liquid chromatography/mass spectrometric methods have been validated and are routinely used in the analysis of samples for a very limited number of these compounds, but limited data exist characterizing the electrospray ionization (ESI) and mass spectrometric fragmentation pathways of the compound families. This report describes results from direct infusion ESI/MS, ESI/MS(2) and ESI/MS(3) analysis of 14 G and V agents, the major OPNA families, using an AB Sciex 4000 QTrap. Using a range of conditions, spectra were acquired and characteristic fragments identified. The results demonstrated that the reproducible and predictable fragmentation of these compounds by ESI/MS, ESI/MS(2) and ESI/MS(3) can be used to describe systematic fragmentation pathways specific to compound structural class. These fragmentation pathways, in turn, may be useful as a predictive tool in the analysis of samples by screening and confirmatory laboratories to identify related compounds for which authentic standards are not readily available.

  13. NaCl胁迫对洋甘菊种子萌发与幼苗生长和生理指标及解剖结构的影响%Effects of NaCl stress on seed germination and seedling growth, physiological index and anatomical structure of Matricaria chamomilla

    Institute of Scientific and Technical Information of China (English)

    邰玉玲; 杨秀梅; 袁艺; 江玲; 余德强; 胡芳

    2013-01-01

    Status of seed germination,changes of seedling growth and some physiological indexes in leaf of Matricaria chamomilla Linn.under NaCl stress condition with mass ratios of 0.2%,0.4%,0.6%,0.8%,1.0%,1.2% and 1.4% were analyzed,and change of transection anatomical structure of its different organs after NaCl stress was also observed by paraffin method.The results show that with rising of NaCl mass ratio,relative germination rate,germination energy and germination rate of seeds gradually decrease,while relative salt injury rate gradually increases; root length,plant height,fresh and dry weights per plant of seedlings gradually decrease,but decreasing range of root length is larger than that of plant height and that of fresh weight is larger than that of dry weight; chlorophyll content in leaf appears a trend of firstly increasing and then decreasing,while soluble sugar content,proline content and POD activity appear a gradually increasing trend.Under NaCl stress condition,relative germination rate,germination energy and germination rate of seeds all are extremely significantly (P<0.01) or significantly (P<0.05) lower than those of the control (0.0% NaCl),except 0.2% NaCl treatment group,relative salt injury rate of other treatment groups is extremely significantly higher than that of the control,and under 1.4% NaCl stress condition,all seeds can not germinate normally.Under NaCl stress condition,root length,plant height,fresh and dry weights per plant of seedlings of all treatment groups are significantly or extremely significantly lower than those of the control,while soluble sugar content,proline content and POD activity in leaf are significantly or extremely significantly higher than those of the control; and except 1.2% NaCl treatment group,chlorophyll content of other treatment groups is also extremely significantly higher than that of the control.Under NaCl stress condition,there are obvious changes in plant morphology and transection

  14. Magnetic and structural properties of yellow europium oxide compound and Eu(OH){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dongwook, E-mail: dongwookleedl324@gmail.com [Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE (United Kingdom); Seo, Jiwon, E-mail: jiwonseo@yonsei.ac.kr [Department of Physics and IPAP, Yonsei University, Seoul 120-749 (Korea, Republic of); Valladares, Luis de los Santos [Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE (United Kingdom); Avalos Quispe, O. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima, Perú (Peru); Barnes, Crispin H.W. [Cavendish Laboratory, University of Cambridge, J. J Thomson Av., Cambridge CB3 0HE (United Kingdom)

    2015-08-15

    A new material based on a yellow europium oxide compound was prepared from europium oxide in a high vacuum environment. The structural and magnetic properties of the material were investigated. Owing to the absence of a crystal structure, the material exhibited a disordered magnetic behavior. In a reaction with deionized (DI) water without applied heat, the compound assumed a white color as soon as the DI water reached the powder, and the structure became polycrystalline Eu(OH){sub 3}. The magnetic properties, such as the thermal hysteresis, disappeared after the reaction with DI water, and the magnetic susceptibility of the yellow oxide compound weakened. The magnetic properties of Eu(OH){sub 3} were also examined. Although Eu{sup 3+} is present in Eu(OH){sub 3}, a high magnetic moment due to the crystal field effect was observed. - Graphical abstract: (top left) Optical image of the yellow europium oxide compound. (top right) Optical image of the product of DI water and yellow europium oxide. (bottom) Magnetization curves as a function of temperature measured in various magnetic field. - Highlights: • We prepared a new material based on a yellow europium oxide compound from europium oxide. • We characterized the magnetic properties of the material which exhibits a disordered magnetic behavior such as thermal hysteresis. • The compound turned white (Eu(OH){sub 3}) as soon as the DI water reached the powder. • The thermal hysteresis disappeared after the reaction with DI water and the magnetic susceptibility of the yellow oxide compound weakened.

  15. Structural characterisation of Tpx from Yersinia pseudotuberculosis reveals insights into the binding of salicylidene acylhydrazide compounds.

    Directory of Open Access Journals (Sweden)

    Mads Gabrielsen

    Full Text Available Thiol peroxidase, Tpx, has been shown to be a target protein of the salicylidene acylhydrazide class of antivirulence compounds. In this study we present the crystal structures of Tpx from Y. pseudotuberculosis (ypTpx in the oxidised and reduced states, together with the structure of the C61S mutant. The structures solved are consistent with previously solved atypical 2-Cys thiol peroxidases, including that for "forced" reduced states using the C61S mutant. In addition, by investigating the solution structure of ypTpx using small angle X-ray scattering (SAXS, we have confirmed that reduced state ypTpx in solution is a homodimer. The solution structure also reveals flexibility around the dimer interface. Notably, the conformational changes observed between the redox states at the catalytic triad and at the dimer interface have implications for substrate and inhibitor binding. The structural data were used to model the binding of two salicylidene acylhydrazide compounds to the oxidised structure of ypTpx. Overall, the study provides insights into the binding of the salicylidene acylhydrazides to ypTpx, aiding our long-term strategy to understand the mode of action of this class of compounds.

  16. Synthesis, Structure and Properties of Two Photochromic Compounds Containing A Pyrazolone-ring

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two photochromic compounds with the pyrazolone-ring as the photochromic functional structure, 2-(1'-phenyl-3'-methyl-4'-benzoformyl-pyrazolone-5')-thiosemicarbazone(PMBP-TSC) and 2-(1'-phenyl-3'-methyl-4'-benzoformyl-pyrazolone-5')-S-methylthiosemicarbazone(PMBP-MTSC), were synthesized and characterized by elemental analysis, MS, IR spectra, NMR spectra. The crystal structure of the photocolored product of PMBP-TSC was determined by single crystal XRD analysis. The results show that the photochromic phenomenon is due to the photoisomerization from enol form to keto form. Their photochromic properties were studied by powder-UV reflectance spectra under the irradiation of 200-380 nm light. The first-order rate constants of the photocoloring reaction were found to be 7.80×10-3 s-1 for compound 1A and 1.03×10-3 s-1 for compound 2A.

  17. New intermetallic compounds with the ErCuCd{sub 2} type of structure

    Energy Technology Data Exchange (ETDEWEB)

    Zelinska, O.Ya.; Solokha, P.G.; Pavlyuk, V.V

    2004-03-24

    The crystal structure of new RTZn{sub 2} intermetallic compounds (R=La, Ce, Tb; T=Co, Cu) was determined. The X-ray diffraction data showed that these compounds are isostructural to the new ternary compound ErCuCd{sub 2}, which was found to crystallize with a superstructure of the ErCd{sub 3} structure type (space group Cmcm, Pearson code oS16, a=0.7097(1) nm, b=1.0659(3) nm, c=0.4471(1) nm, V=0.3382(2) nm{sup 3}, Z=4). The obtained reliability factors are R{sub F}=0.0240 and R{sub w}=0.1127 for 235 unique reflections (vertical barF{sub 0} vertical bar>4.00{sigma}|F{sub 0}|)

  18. Synthesis and crystal structures of coordination compounds of pyridoxine with zinc and cadmium sulfates

    Science.gov (United States)

    Furmanova, N. G.; Berdalieva, Zh. I.; Chernaya, T. S.; Resnyanskiĭ, V. F.; Shiitieva, N. K.; Sulaĭmankulov, K. S.

    2009-03-01

    The pyridoxine complexes with zinc and cadmium sulfates are synthesized. The IR absorption spectra and thermal behavior of the synthesized compounds are described. Crystals of the [ M(C8H11O3N)2(H2O)2]SO4 · 3H2O ( M = Zn, Cd) compounds are investigated using X-ray diffraction. In the structures of both compounds, the M atoms are coordinated by the oxygen atoms of the deprotonated OH group and the CH2OH group retaining its own hydrogen atom, as well as by two H2O molecules, and have an octahedral coordination. The nitrogen atom of the heterocycle is protonated, so that the heterocycle acquires a pyridinium character. The cationic complexes form layers separated by the anions and crystallization water molecules located in between. The structural units of the crystals are joined together by a complex system of hydrogen bonds.

  19. Structural, electronic and elastic properties of REIr2 (RE=La and Ce) Laves phase compounds

    Science.gov (United States)

    Shrivastava, Deepika; Fatima, Bushra; Sanyal, Sankar P.

    2016-05-01

    REIr2 (RE = La and Ce) Laves phase intermetallic compounds were investigated with respect to their structural, electronic and elastic properties using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) as implemented in WIEN2k code. The ground state properties such as lattice constants (a0), bulk modulus (B), pressure derivative of bulk modulus (Bꞌ) and density of state at Fermi level N(EF) have been obtained by optimization method. The electronic structure (BS, TDOS and PDOS) reveals that these Laves phase compounds are metallic in nature. The calculated elastic constants indicate that these compounds are mechanically stable at ambient pressure and found to be ductile in nature.

  20. QSAR study on estrogenic activity of structurally diverse compounds using generalized regression neural network

    Institute of Scientific and Technical Information of China (English)

    JI Li; WANG XiaoDong; LUO Si; QIN Liang; YANG XvShu; LIU ShuShen; WANG LianSheng

    2008-01-01

    Computer-based quantitative structure-activity relationship (QSAR) model has been becoming a powerful tool in understanding the structural requirements for chemicals to bind the estrogen receptor (ER), designing drugs for human estrogen replacement therapy, and identifying potential estrogenic endocrine disruptors, in this study, a simple yet powerful neural network technique, generalized regression neural network (GRNN) was used to develop a QSAR model based on 131 structurally diverse estrogens (training set). Only nine descriptors calculated solely from the molecular structures of compounds selected by objective and subjective feature selections were used as inputs of the GRNN model. The predictive power of the built model was found to be comparable to that of the more traditional techniques but requiring significantly easy implementation and a shorter computation-time. The obtained result indicates that the proposed GRNN model is robust and satisfactory, and can provide a feasible and practical tool for the rapid screening of the estrogenic activity of organic compounds.

  1. Crystal Structure and Magnetic Studies of a New Nitronyl Nitroxide Compound

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Compound 1 was first synthesized and characterized. Its crystal structure and magnetic property were determined and investigated. Discussion about the molecule packing in crystal and the macroscopic magnetism was also presented, in combination with computing study of the spatial distribution over the molecule.

  2. Structure of metal-rich (001) surfaces of III-V compound semiconductors

    DEFF Research Database (Denmark)

    Kumpf, C.; Smilgies, D.; Landemark, E.

    2001-01-01

    feature of the structure is accompanied by linear arrays of atoms on nonbulklike sites at the surface which, depending on the compounds, exhibit a certain degree of disorder. A tendency to group-III-dimer formation within these chains increases when descending the periodic table. We propose that all the c...

  3. The Influence of Morphological Structure Information on the Memorization of Chinese Compound Words

    Science.gov (United States)

    Liu, Duo

    2017-01-01

    The present study investigated the influence of morphological structure information on the memorization of Chinese subordinate and coordinative compound words using the memory conjunction error paradigm. During the Study Phase, Hong Kong Chinese college students were asked to either judge the word class (Exp. 1, N = 25) or the orthographic…

  4. Crystal structure of ABPO5 and optical study of Pr3+ embedded in these compounds

    Science.gov (United States)

    Ben Ali, A.; Antic-Fidancev, E.; Viana, B.; Aschehoug, P.; Taibi, M.; Aride, J.; Boukhari, A.

    2001-10-01

    The crystal structure of borophosphates ABPO5 (A = alkaline earth or Pb) was resolved on a polycrystalline sample using the Rietveld method. The x-ray diffraction patterns data show that ABPO5 crystallize in a centrosymmetric space group P3121 and their structure is related to the borogermanates REBGeO5 with a stillwellite-type structure. Pr3+ ion was used as a local structural probe to corroborate the structural resolution results. Absorption and fluorescence spectra of A1-xPrxBP1-xGexO5 (A = alkaline earth or Pb; x = 0.05) have been investigated at different temperatures. At 9 K the 3H4 → 3P0 transition of trivalent praseodymium ion (4f2 configuration) is observed as a single line. This indicates a unique crystallographic site for the rare earth ion in these compounds replacing the divalent cation. Energy level schemes were deduced from the low-temperature spectroscopic measurements. Comparing the electronic level splittings of studied compounds with the already reported data on REBGeO5 doped with Pr3+ ion, it is possible to dispel the doubt existing about structural determination. Moreover, under 460 nm excitation, intense red emission of trivalent praseodymium is observed corresponding to 1D2 → 3H4 transition. The lifetime measurements of 1D2 level have been performed for all the title compounds.

  5. Crystal structure re-investigation in wide band gap CIGSe compounds

    Energy Technology Data Exchange (ETDEWEB)

    Souilah, M. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03 (France)], E-mail: marc.souilah@cnrs-imn.fr; Rocquefelte, X.; Lafond, A.; Guillot-Deudon, C. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03 (France); Morniroli, J.-P. [Laboratoire de Metallurgie Physique et Genie des Materiaux, UMR CNRS 8517, USTL and ENSCL, Bat C6, Cite Scientifique, 59655 Villeneuve d' Ascq Cedex (France); Kessler, J. [Institut des Materiaux Jean Rouxel, Universite de Nantes, CNRS, 2 rue de la Houssiniere, BP 32229, 44322 Nantes Cedex 03 (France)

    2009-02-02

    There is agreement in the literature that Cu(In{sub 1} {sub -} {sub x}Ga{sub x})Se{sub 2} (CIGSe) absorber used in solar cells has an optimum composition (x {approx} 0.3) corresponding to a band gap (1.1-1.2 eV) far below the theoretical value giving the maximum (1.4-1.5 eV). This paper presents a re-investigation of the crystal structure of bulk CIGSe compounds for both stoichiometric and Cu-poor compositions. Regardless of the gallium content, all the stoichiometric compounds are found to adopt the well-known chalcopyrite structure (space group I-42d) while a modification of the structure is evidenced for the high Ga-content Cu-poor compounds. The X-ray diffraction analyses demonstrate that the crystal structure of Cu{sub 0.743}In{sub 0.543} Ga{sub 0.543}Se{sub 2} is derived from that of the stannite structure (space-group I-42m). Ab-initio calculations show a strong dependence of the electronic structure near the Fermi level with the copper content. Such modifications are expected to significantly change the optical properties of Cu-poor CIGSe materials.

  6. Phase Changes of Monosulfoaluminate in NaCl Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Seyoon Yoon

    2016-05-01

    Full Text Available Monosulfoaluminate (Ca4Al2(SO4(OH12∙6H2O plays an important role in anion binding in Portland cement by exchanging its original interlayer ions (SO42− and OH− with chloride ions. In this study, scanning transmission X-ray microscope (STXM, X-ray absorption near edge structure (XANES spectroscopy, and X-ray diffraction (XRD were used to investigate the phase change of monosulfoaluminate due to its interaction with chloride ions. Pure monosulfoaluminate was synthesized and its powder samples were suspended in 0, 0.1, 1, 3, and 5 M NaCl solutions for seven days. At low chloride concentrations, a partial dissolution of monosulfoaluminate formed ettringite, while, with increasing chloride content, the dissolution process was suppressed. As the NaCl concentration increased, the dominant mechanism of the phase change became ion exchange, resulting in direct phase transformation from monosulfoaluminate to Kuzel’s salt or Friedel’s salt. The phase assemblages of the NaCl-reacted samples were explored using thermodynamic calculations and least-square linear combination (LC fitting of measured XANES spectra. A comprehensive description of the phase change and its dominant mechanism are discussed.

  7. Electronic structure and physical properties of Heusler compounds for thermoelectric and spintronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Ouardi, Siham

    2012-03-19

    This thesis focuses on synthesis as well as investigations of the electronic structure and properties of Heusler compounds for spintronic and thermoelectric applications. The first part reports on the electronic and crystal structure as well as the mechanical, magnetic, and transport properties of the polycrystalline Heusler compound Co{sub 2}MnGe. The crystalline structure was examined in detail by extended X-ray absorption fine structure spectroscopy and anomalous X-ray diffraction. The low-temperature magnetic moment agrees well with the Slater-Pauling rule and indicates a half-metallic ferromagnetic state of the compound, as is predicted by ab-initio calculations. Transport measurements and hard X-ray photoelectron spectroscopy (HAXPES) were performed to explain the electronic structure of the compound. A major part of the thesis deals with a systematical investigation of Heusler compounds for thermoelectric applications. This thesis focuses on the search for new p-type Heusler compounds with high thermoelectric efficiency. The substitutional series NiTi{sub 1-x}M{sub x}Sn (where M=Sc, V and 0structure and transport properties. The results show the possibility to create n-type and p-type thermoelectrics within one Heusler compound. The pure compounds showed n-type behavior, while under Sc substitution the system switched to p-type behavior. A maximum Seebeck coefficient of +230 {mu}V/K (350 K) was obtained for NiTi{sub 0.26}Sc{sub 0.04}Zr{sub 0.35}Hf{sub 0.35}Sn. HAXPES valence band measurement show massive in gap states for the parent compounds NiTiSn, CoTiSb and NiTi{sub 0.3}Zr{sub 0.35}Hf{sub 0.35}Sn. This proves that the electronic states close to the Fermi energy play a key role for the behavior of the transport properties. Furthermore, the electronic structure of the gapless Heusler compounds PtYSb, PtLaBi and PtLuSb were investigated by bulk

  8. Isolation and Structural Speculation of Herbicide-Active Compounds from the Metabolites of Pythium aphanidermatum

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-hui; ZHANG Jin-lin; LIU Ying-chao; CAO Zhi-yan; HAN Jian-min; YANG Juan; DONG Jin-gao

    2013-01-01

    Natural herbicides, or environment-friendly bioherbicides have been attracted more and more attentions. Isolation and structural identification of natural herbicide-active compounds from plant pathogens has been proved to be an effective approach for novel lead discovery of the pesticide development. In this study, the metabolites of the mutant strain PAM1, which obtained from PA1 of Pythium aphanidermatum (Eds.) Fitzp by ultraviolet radiation were separated and identified by HPLC, NMR, and IR. The results revealed that three active compounds including 4-hydroxy-3-methoxycinnamic acid and two indole derivatives, exhibited inhibition activity on the elongation of radical and coleoptile of Digtaria sanguinalis (L.) Scop.

  9. Electronic structure and transport properties of the Heusler compound Co{sub 2}TiAl

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Tanja; Fecher, Gerhard H; Barth, Joachim; Winterlik, Juergen; Felser, Claudia, E-mail: fecher@uni-mainz.d [Johannes Gutenberg Universitaet, Institut fuer Analytische und Anorganische Chemie, 55099 Mainz (Germany)

    2009-04-21

    The properties of the Heusler compound Co{sub 2}TiAl were investigated in detail by experimental techniques and theoretical methods. X-ray diffraction measurements indicate that as-cast samples of the compound exhibit the L2{sub 1} structure with a small amount of B2-type disorder. This leads to a reduced saturation magnetization per formula unit of 0.747 {mu}{sub B}. The Curie temperature is approximately 120 K. The transport properties are influenced by the change in the electronic structure at the Curie temperature, as revealed experimentally by conductivity, thermal transport and specific heat measurements. Different theoretical models based on ab initio calculations of the electronic structure are used to explain the experimental observations.

  10. Magnetic structure of ErT{sub x}Sn{sub 2} (T = Co, Ni) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Penc, B.; Wawrzynska, E.; Szytula, A.; Gil, A.; Hernandez-Velasco, J.; Zygmunt, A

    2004-07-28

    In this work, the magnetic properties and magnetic structure of the ErT{sub x}Sn{sub 2} (T=Co, Ni) stannides are reported. These compounds crystallize in the orthorhombic CeNiSi{sub 2}-type structure and are antiferromagnets with the Neel temperature equal to 4.7 K for ErCo{sub 0.24}Sn{sub 2} and 4 K for ErNi{sub 0.15}Sn{sub 2}. Neutron diffraction measurements indicate the presence of the collinear magnetic structure described by the propagation vector k=(0,0,1/2)

  11. Molecules and Models The molecular structures of main group element compounds

    CERN Document Server

    Haaland, Arne

    2008-01-01

    This book provides a systematic description of the molecular structures and bonding in simple compounds of the main group elements with particular emphasis on bond distances, bond energies and coordination geometries. The description includes the structures of hydrogen, halogen and methyl derivatives of the elements in each group, some of these molecules are ionic, some polar covalent. The survey of molecules whose structures conform to well-established trends is followed byrepresentative examples of molecules that do not conform. We also describe electron donor-acceptor and hydrogen bonded co

  12. Structural instability of the ground state of the U2Mo compound

    OpenAIRE

    Losada, Edith L.; Garcés, Jorge E.

    2015-01-01

    This work reports the structural instability at T=0 K of the U2Mo compound in the structure C11b under the distortion related to the C66 elastic constant. The electronic properties of U2Mo such density of states (DOS), bands and Fermi surface (FS) are studied to understand the source of the instability. The C11b structure can be interpreted as formed by parallel linear chains along the z-directions each one composed by successive U-Mo-U blocks. The hybridization due to electronic interactions...

  13. Determination of Monod kinetics of toxic compounds by respirometry for structure-biodegradability relationships

    Energy Technology Data Exchange (ETDEWEB)

    Govind, R.; Desai, S.; Tabak, H.H.

    1990-01-01

    The key to the evaluation of the fate of toxic organic chemicals in the environment is dependant on evaluating their susceptibility to biodegradation. Biodegradation is one of the most important mechanisms in controlling the concentration of chemicals in an aquatic system because toxic pollutants can be mineralized and rendered harmless. Experiments using an electrolytic respirometer have been conducted to collect oxygen consumption data of toxic compounds from the list of RCRA and RCRA land banned chemicals (phenols and phthalates). The estimation of Monod kinetic parameters were obtained for all the compounds by a graphical method. The first order kinetic constants for the substituted phenols were related to the structure of the compounds by the group contribution method.

  14. Synthesis, structure, and properties of a novel family of layered transition nitride compounds

    Science.gov (United States)

    Weil, Kenneth Scott

    The chemical properties of nitrogen present a number of difficulties in the synthesis of nitride compounds. Most of these compounds have small free energies of formation due in part to the strong triple bond of N2. Thus the standard solid state approach of synthesizing compounds from a mixture of their constituents at high reaction temperatures is generally precluded. A general alternative to solid state synthesis is the molecularly mixed precursor route. The primary advantage of this approach is the control of composition. This concept has been demonstrated in this study through the use of a nonaqueous, complexed co-precipitation technique to synthesize a number of new ternary nitride compounds, including the a new nitride phase, CrWN2, and four series of substitutional variations of this compound, as wen as twelve additional new compounds crystallizing in the layered dinitride, eta-nitride, and pi-nitride crystal structures. The layered nitride, CrWN2, is the focal point of this thesis. The details of its crystal and defect structure, synthesis, properties, and substitutional chemistry have been examined and discussed within. Briefly, this compound crystallizes in a trigonal structure and consists of alternating layers of chromium in octahedral coordination with nitrogen and tungsten in trigonal prismatic coordination with nitrogen. Microstructurally, the nitride frequently displays twinning and the formation of coherent rock salt structured intergrowth defects. As mentioned above, the layered nitride evolves from a co-precipitated precursor; a fine mixture of [Cr(NH3)6]Cl 2 and WOCl2·3NH3. Upon heat treatment in an ammonia atmosphere, the two transition metal complexes separately decompose into their non-complexed chloride state, i.e. CrCl2 and WOCl 2, before reacting with each other and the ambient ammonia atmosphere between 420°C and 570°C to form a glassy oxynitrochloride phase, CrWO 1.01N0.36Cl2.45. Around 600°C, this compound undergoes ammonolysis

  15. Molecular Descriptors Family on Structure Activity Relationships 4. Molar Refraction of Cyclic Organophosphorus Compounds

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2005-06-01

    Full Text Available The molecular descriptors family on structure activity relationships methodology was applied on ten cyclic organophosphorus compounds in order to predict theirs molar refraction. A number of 107692 significantly different MDF members enter into a multiple linear regression analysis. A pair of descriptors (lGDmSMt, lAmrfEt, which have the best performing ability in prediction of molar refraction of cyclic organophosphorus compounds, was found and a bi-varied MDF SAR model was built. After performing leave-one-out cross-validation, satisfactory result was obtained with cross-validation r2cv and r2 values of 0.9999 and 0.9999. The external validation of the bi-varied MDF SAR model and its ability in prediction of molar refraction of cyclic organophosphorus compounds is demonstrated by the results obtained in training vs. test experiment. The correlated correlation results proved us that the ability in prediction of molar refraction of cyclic organophosphorus compounds with bi-varied MDF SAR model is significantly better compared with the previous reported SAR (see pZ = 0.0 % from Steiger’s Z test. The results showed clearly that the molar refraction of cyclic organophosphorus compounds is almost of topological nature (99.99%, and is strongly dependent on atomic relative mass and atomic electronegativity.

  16. Prediction of heats of sublimation of nitroaromatic compounds via their molecular structure.

    Science.gov (United States)

    Keshavarz, Mohammad Hossein

    2008-03-01

    This work presents a new approach to predict heats of sublimation of nitroaromatic compounds derived from their molecular structure information. The number of carbon, hydrogen and nitrogen atoms as well as the contribution of some specific groups attached to aromatic ring would be needed in the new method. Predicted heats of sublimation for 40 nitroaromatic compounds are compared with experimental data. Calculated results for some nitroaromatic compounds are also compared with complicated quantum mechanical computations of Rice et al. [B. M. Rice, S. V. Pai, J. Hare, Combust. Flame 118 (1999) 445] where computed outputs were available. The root mean square deviation (rms) from experiment for the predicted heats of sublimation of 40 compounds by new method is 7.78 kJ/mol with a maximum deviation of 18.52 kJ/mol. The rms deviations of new procedure and reported quantum mechanical method for six nitroaromatic compounds are 9.19 and 10.18 kJ/mol, respectively.

  17. Crystal structures and luminescence of two cadmium-carboxylate cluster-based compounds with mixed ligands

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Hui-Fang; Lei, Qian; Wang, Yu-Ling; Yin, Shun-Gao; Liu, Qing-Yan [College of Chemistry and Chemical Engineering and Key Lab. of Functional Small Organic Molecule of Ministry of Education, Jiangxi Normal Univ., Nanchang (China)

    2017-04-04

    Reactions of Cd(NO{sub 3}){sub 2}.4H{sub 2}O with 2-quinolinecarboxylic acid (H-QLC) in the presence of 1,4-benzenedicarboxylic acid (H{sub 2}-BDC) or 1,3,5-benzenetricarboxylic acid (H-BTC) in DMF/H{sub 2}O solvent afforded two compounds, namely, [Cd(QLC)(BDC){sub 1/2}(H{sub 2}O)]{sub n} (1) and [Cd(QLC)(BTC){sub 1/3}]{sub n} (2). Both compounds are two-dimensional (2D) frameworks but feature different cadmium-carboxylate clusters as a result of the presence of the polycarboxylate ligands with different geometries and coordination preference. The dinuclear Cd{sub 2}(QLC){sub 2} units in 1 are bridged by the pairs of bridging water ligands to give a one-dimensional (1D) chain, which is further linked by the second ligand of BDC{sup 2-} to form a 2D structure. Compound 2 is constructed from unique hexanuclear macrometallacyclic Cd{sub 6}(QLC){sub 6} clusters, which are linked by the surrounding BTC{sup 3-} ligands to generate a 2D structure. Photoluminescence studies showed both compounds exhibit ligand-centered luminescent emissions with emission maxima at 405 and 401 nm, respectively. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Band Structure and Optical Properties of Kesterite Type Compounds: first principle calculations

    Science.gov (United States)

    Palaz, S.; Unver, H.; Ugur, G.; Mamedov, A. M.; Ozbay, E.

    2017-02-01

    In present work, our research is mainly focused on the electronic structures, optical and magnetic properties of Cu2FeSnZ4 (Z = S, Se) compounds by using ab initio calculations within the generalized gradient approximation (GGA). The calculations are performed by using the Vienna ab-initio simulation package (VASP) based on the density functional theory. The band structure of the Cu2FeSnZ4 ( Z = S, Se) compounds for majority spin (spin-up) and minority spin (spin-down) were calculated. It is seen that for these compounds, the majority spin states cross the Fermi level and thus have the metallic character, while the minority spin states open the band gaps around the Fermi level and thus have the narrow-band semiconducting nature. For better understanding of the electronic states, the total and partial density of states were calculated, too. The real and imaginary parts of dielectric functions and hence the optical functions such as energy-loss function, the effective number of valance electrons and the effective optical dielectric constant for Cu2FeSnZ4 (Z = S, Se) compounds were also calculated.

  19. Thorium Compounds with Bonds to Sulfur or Selenium: Synthesis, Structure, and Thermolysis.

    Science.gov (United States)

    Rehe, David; Kornienko, Anna Y; Emge, Thomas J; Brennan, John G

    2016-07-18

    Thorium chalcogenolates Th(ER)4 (E = S, Se; R = Ph, C6F5) form pyridine complexes with a variety of coordination numbers. Four compounds, (py)4Th(SPh)4, (py)3Th(SePh)4, (py)3Th(SC6F5)4, and (py)4Th(SeC6F5)4, have been isolated and characterized by spectroscopic methods and low-temperature single crystal X-ray diffraction. Two of the products, (py)4Th(SPh)4 and (py)4Th(SeC6F5)4, have classic eight coordinate A4B4 square-antiprism geometries. The SePh compound is the only seven coordinate (4Se, 3N) product, and the fluorinated thiolate is distinctive in that the structure contains two dative interactions between Th and fluoride, to give a nine coordinate (3N, 4S, 2F) structure. The EPh compounds decompose thermally to give ThE2 and EPh2, while the fluorinated compounds give primarily ThF4, E2(C6F5)2, and E(C6F5)2.

  20. Crystal Structure and Characterization of a Novel Neodymium Coordination Compound Based on Dawson Cluster

    Institute of Scientific and Technical Information of China (English)

    王敬平; 魏梅林; 牛景杨

    2004-01-01

    A new coordination compound, [{Nd(NMP)2(H2O)6Cl}{Nd(NMP)2(H2O)7}H (P2Mo18O62) (NMP=N-methyl-2-pyrrolidone) was synthesized and characterized by elemental analyses, IR spectrum, and X-ray single crystal structural analysis. The crystal structure indicates that the title compound belongs to monoclinic space group Cc, with unit cell dimensions a=2.4528(5) nm, b=1.9495(4) nm, c=2.4405(5) nm, β=109.94(3)°, Z=4, V=10.970 (4) nm3, Dc=2.262 g*cm-3, R1=0.0676, wR2=0.1441. The ESR spectrum of powder of the title compound at 110 K after being exposed to sunlight shows the signal of Mo5+, g=1.95. Cyclic voltammetry was measured in aqueous solution containing 0.1 mol*L-1 KCl as the supporting electrolyte and shows that the title compound undergoes two one-electron reversible reductions.

  1. Crystal Structure Effects on the Thermal Conductivity of Cu-Ge-Se Compounds

    Science.gov (United States)

    Skoug, Eric; Cain, Jeffrey; Morelli, Donald

    2010-03-01

    One approach to increasing the efficiency of a thermoelectric material is to decrease its thermal conductivity without degrading its electronic properties. Traditionally this has been accomplished, for instance, by forming solid solutions between compounds with similar crystal structures, or, more recently, by inducing nanostructure in the crystal lattice. These methods have proven effective in many cases; however discovering compounds with intrinsically low thermal conductivity provides a fundamental solution to the same problem. Here we describe our initial efforts in synthesis and characterization of compounds of the series Cu2Ge1+xSe3, in which we observe a transition from orthorhombic to cubic symmetry at x = 0.55. The lattice thermal conductivity of the cubic phase is significantly lower than that of the orthorhombic phase, which we discuss here in relation to vacancies and anti-site defects. A simple valence argument is presented suggesting a change in the nominal valence of Ge as x approaches 1.0, which we speculate contributes to increased bond anharmonicity in the cubic-structure compounds.

  2. Structure and properties of quarternary and tetragonal Heusler compounds for spintronics and spin transver torque applications

    Energy Technology Data Exchange (ETDEWEB)

    Zamani, Vajiheh Alijani

    2012-03-07

    This work is divided into two parts: part 1 is focused on the prediction of half-metallicity in quaternary Heusler compounds and their potential for spintronic applications and part 2 on the structural properties of Mn{sub 2}-based Heusler alloys and tuning the magnetism of them from soft to hard-magnetic for spin-transfer torque applications. In part 1, three different series of quaternary Heusler compounds are investigated, XX'MnGa (X=Cu, Ni and X'=Fe,Co), CoFeMnZ (Z=Al,Ga,Si,Ge), and Co{sub 2-x}Rh{sub x}MnZ (Z=Ga,Sn,Sb). All of these quaternary compounds except CuCoMnGa are predicted to be half-metallic ferromagnets by ab-initio electronic structure calculations. In the XX'MnGa class of compounds, NiFeMnGa has a low Curie temperature for technological applications but NiCoMnGa with a high spin polarization, magnetic moment, and Curie temperature is an interesting new material for spintronics applications. All CoFeMnZ compounds exhibit a cubic Heusler structur and their magnetic moments are in fair agreement with the Slater-Pauling rule indicating the halfmetallicity and high spin polarization required for spintronics applications. Their high Curie temperatures make them suitable for utilization at room temperature and above. The structural investigation revealed that the crystal structure of all Co{sub 2-x}Rh{sub x}MnZ compounds aside from CoRhMnSn exhibit different types of anti-site disorder. The magnetic moments of the disordered compounds deviate from the Slater-Pauling rule indicating that 100% spin polarization are not realized in CoRhMnGa, CoRhMnSb, and Co{sub 0.5}Rh{sub 1.5}MnSb. Exchange of one Co in Co{sub 2}MnSn by Rh results in the stable, well-ordered compound CoRhMnSn. This exchange of one of the magnetic Co atoms by a non-magnetic Rh atom keeps the magnetic properties and half-metallicity intact. In part 2, two series of Mn{sub 2}-based Heusler alloys are investigated, Mn{sub 3-x}Co{sub x}Ga and Mn{sub 2-x}Rh{sub 1+x}Sn. It has been

  3. Thermodynamic Optimization of DyCl3 -NaCl System

    Institute of Scientific and Technical Information of China (English)

    叶信宇; 孙益民; 张静; 谈君君

    2005-01-01

    In this paper, the phase diagram of the DyCl3 -NaCl system is optimized and calculated with CALPHAD ( calculation of phase diagram ) technology. A set of thermodynamic functions of compounds Na3 DyCl6, NaDyCl4, and NaDY2 Cl7 have been optimized and calculated based on an interactive computer-assisted analysis. The optimized thermodynamic parameters, calculated phase diagram and experimental phase diagram are thermodynamically serf-consistent.

  4. A QSPR model for estimation of lower flammability limit temperature of pure compounds based on molecular structure.

    Science.gov (United States)

    Gharagheizi, Farhad

    2009-09-30

    In this study, a quantitative structure-property relationship was presented to estimate lower flammability limit temperature (LFLT) of pure compounds. This relationship is a multi-linear equation and has six parameters. These chemical structure-based parameters were selected from 1664 molecular-based parameters by genetic algorithm multivariate linear regression (GA-MLR). Since 1171 compounds were used to develop this equation, the model can be used to estimate the LFLT of a wide range of pure compounds.

  5. Structural characterization of the ternary compound Cu{sub 3}TaSe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gerzon E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela)]. E-mail: gerzon@ula.ve; Mora, Asiloe J. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Duran, Sonia [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Munoz, Marcos [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Grima-Gallardo, Pedro [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela)

    2007-07-31

    The Cu{sub 3}TaSe{sub 4} compound crystallizes in the cubic P4bar 3m (No. 215) space group, Z=1, with a=5.6600(1)A, V=181.32(1)A{sup 3}. Its structure was refined from X-ray powder diffraction data using the Rietveld method. The refinement of 21 instrumental and structural variables led to R{sub p}=12.2%, R{sub wp}=14.7%, R{sub exp}=8.0%, R{sub B}=14.5% and S=1.8, for 4501 step intensities and 33 independent reflections. This compound is isostructural with the sulvanite mineral and is characterized for a three-dimensional arrangement of CuSe{sub 4} and TaSe{sub 4} tetrahedra connected by common edges, and the CuSe{sub 4} tetrahedra sharing vertexes among them.

  6. Magnetic structures of RCu{sub x}Ge{sub 2} (R=Ho, Er) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gil, A.; Kaczorowski, D.; Hernandez-Velasco, J.; Penc, B.; Wawrzynska, E.; Szytula, A

    2004-12-14

    Neutron powder diffraction and magnetic measurements have been carried out on RCu{sub x}Ge{sub 2} (R=Ho, Er) compounds. Both compounds crystallize in the orthorhombic CeNiSi{sub 2}-type structure (space group Cmcm) and they are antiferromagnets with the Neel temperature equal to 4.5 K for R=Er and 8.0 K for R=Ho. Neutron diffraction measurements indicate the presence of collinear magnetic structures of the G{sub z} mode in HoCu{sub 0.33}Ge{sub 2} and G{sub x} mode in ErCu{sub 0.25}Ge{sub 2}.

  7. Surface induces different crystal structures in a room temperature switchable spin crossover compound.

    Science.gov (United States)

    Gentili, Denis; Liscio, Fabiola; Demitri, Nicola; Schäfer, Bernhard; Borgatti, Francesco; Torelli, Piero; Gobaut, Benoit; Panaccione, Giancarlo; Rossi, Giorgio; Degli Esposti, Alessandra; Gazzano, Massimo; Milita, Silvia; Bergenti, Ilaria; Ruani, Giampiero; Šalitroš, Ivan; Ruben, Mario; Cavallini, Massimiliano

    2016-01-01

    We investigated the influence of surfaces in the formation of different crystal structures of a spin crossover compound, namely [Fe(L)2] (LH: (2-(pyrazol-1-yl)-6-(1H-tetrazol-5-yl)pyridine), which is a neutral compound thermally switchable around room temperature. We observed that the surface induces the formation of two different crystal structures, which exhibit opposite spin transitions, i.e. on heating them up to the transition temperature, one polymorph switches from high spin to low spin and the second polymorph switches irreversibly from low spin to high spin. We attributed this inversion to the presence of water molecules H-bonded to the complex tetrazolyl moieties in the crystals. Thin deposits were investigated by means of polarized optical microscopy, atomic force microscopy, X-ray diffraction, X-ray absorption spectroscopy and micro Raman spectroscopy; moreover the analysis of the Raman spectra and the interpretation of spin inversion were supported by DFT calculations.

  8. A new extended structural compound based on saturated Wells-Dawson polyoxoanions

    Institute of Scientific and Technical Information of China (English)

    Min Xu; Jia Liu; En Bo Wang

    2009-01-01

    A new 3D extended structural compound, (dpdo)_2H_2{[Cu(2,2'-bipy)_2]2(P_2W_(18)O_(62))}.5H_2O 1 (dpdo = 4,4'-bipyridine-N,N'-dioxide; 2,2'-bipy = 2,2'-bipyridine), has been hydrothermally synthesized and characterized by elemental analyses, IR, TG analyses, cyclic voltammetry, and single-crystal X-ray diffraction. Compound 1 is built up of [PEW_(18)O_(62)]~(6-) cluster as the structural motif covalently linked by [Cu(2,2'-bipy)_2]~(2+) coordination complexes to yield the 1D chains, which are further in close contact forming a 3D supramolecular framework via aromatic π-π stacking interactions and extensive hydrogen-bonding interactions among polyoxoaulons, coordinated 2,2'-bipy organic ligands, free dpdo organic molecules and lattice water molecules.

  9. STRUCTURE AND MAGNETIC PROPERTIES OF YFe12-xTix COMPOUNDS

    Institute of Scientific and Technical Information of China (English)

    B. Fuquan; J.L. Wang; N. Tang; W.Q. Wang; Z.Z. Guo; G.H. Wu; F.M. Yang

    2001-01-01

    Structure and magnetic properties of the YFe12-x Tix compounds with x=0.85, 1.00,1.10, 1.20 and 1.30 have been investigated. Both the therrnomagnetic analysis and X-ray diffraction patterns show that all compounds studied are almost single phase and crystallize in the ThMn12-type of structure. The lattice parameters a, c and unit cell volume V increase monotonously with increasing Ti content. Curie temperature TC is almost independent on Ti content while the spontaneous magnetization M0,the anisotropy field Ba and the anisotropy constant K1 decrease monotonously with increasing Ti content and increasing temperature from 1.5K to 293K.

  10. Synthesis and Crystal Structure of Compound [ZnS6 (C12H8N2)

    Institute of Scientific and Technical Information of China (English)

    陈之荣; 李健晖; 李鸿钧; 苏卫平; 曹荣

    2000-01-01

    The title compound ZnS6(C12H8N2) was obtained by reaction of zinic powder with sulfur and 1,10-phenathtroline in DMF solvent, and its structure has been determined by single crystal X-ray diffraction analysis. The crystal data for the compound: triclinic, P-1, Z = 2, a = 8. 159(2), b = 9. 485(2), c = 11. 997(2)A , α =110. 00(3)°,β = 99.22(3)°, γ = 100.57(3)°, V = 832A3, Dc =1. 748g/cm3, μ(MoKa)=0. 2219 cm-1, F(000)=440. The structure was refined to R = 0. 0723 and Rw = 0. 0865 for 1427 independent observed reflections. The tilte crystal consists of a discrete molecules, in which the core of ZnS2N2 shows a distorted tetrahedral geometry.

  11. Double-flat-spiral magnetic structures: Theory and application to the RMn6X6 compounds

    Science.gov (United States)

    Rosenfeld, E. V.; Mushnikov, N. V.

    2008-05-01

    We studied magnetic structure of a layered magnetic material, the lattice of which consists of magnetic layers separated by alternating non-magnetic layers (slabs) of two different types. For such structure, the exchange integrals between the nearest magnetic layers separated by different slabs may have different values, while the next-nearest neighbor exchange integral is the same for all magnetic layers. We developed a model based on three different interlayer exchange integrals. In the framework of this model we analyzed conditions of the appearance of a magnetic structure of the double-flat-spiral type and its distortion in external magnetic field. The results are most obtained in the analytical form. The model was applied to analyze the magnetic structure and magnetization process of the RMn6X6 ( R=Y, Sc, Lu; X=Sn, Ge) compounds with the layered crystal structure.

  12. Structural stability of intermetallic compounds of Mg-Al-Ca alloy

    Institute of Scientific and Technical Information of China (English)

    ZHOU Dian-wu; LIU Jin-shui; ZHANG Jian; PENG Ping

    2007-01-01

    A first-principles plane-wave pseudopotential method based on the density functional theory was used to investigate the energetic and electronic structures of intermetallic compounds of Mg-Al-Ca alloy, such as Al2Ca, Al4Ca and Mg2Ca. The negative formation heat, the cohesive energies and Gibbs energies of these compounds were estimated from the electronic structure calculations, and their structural stability was also analyzed. The results show that Al2Ca phase has the strongest alloying ability as well as the highest structural stability, next Al4Ca, finally Mg2Ca. After comparing the density of states of Al2Ca, Al4Ca and Mg2Ca phases, it is found that the highest structural stability of Al2Ca is attributed to an increase in the bonding electron numbers in lower energy range below Fermi level, which mainly originates from the contribution of valence electron numbers of Ca(s) and Ca(p) orbits, while the lowest structural stability of Mg2Ca is resulted from the least bonding electron numbers near Fermi level.

  13. Syntheses and Structural Characterization of Fırst Paraben Substituted Ferrocenyl Phosphazene Compounds

    Directory of Open Access Journals (Sweden)

    Yasemin Tümer

    2016-11-01

    Full Text Available Parabens have been regarded as a substitute group to increase DNA interactions as well as cytotoxic and antimicrobial activities of ferrocenylphosphazenes. For this reason, new ferrocenylphosphazenes compounds bearing paraben (ethyl-4-hydroxybenzoate have been synthesized for the first time (6-10 and their structures have been determined using elemental analysis, FTIR (Fourier transform, 1H (one-dimensional-1D, 31P NMR techniques and X-ray crystallography (for 9 and 10.

  14. Synthesis, Structure and Antitumour Properties of a New 1,2-Propylenediaminetetraacetate-Ruthenium(III) Compound.

    Science.gov (United States)

    Vilaplana, R; Romero, M A; Quirós, M; Salas, J M; González-Vílchez, F

    1995-01-01

    A novel complex formed by ruthenium (III) and the sequestering ligand 1,2-propylenediaminetetraacetic acid (PDTA) has been synthetized and characterized. The structure of the monomeric compound, studied by X-ray diffraction , shows an almost symmetric octahedral geometry around the metal ion, with two chlorine atoms in a cis conformation. The antitumour activity against a variety of murine and human cancers is reported.

  15. Analysis of the relationship between the structure and aromatic properties of chemical compounds.

    Science.gov (United States)

    Debska, Barbara; Guzowska-Swider, Barbara

    2003-04-01

    This paper presents the results of research on the relationship between the structure and odour properties of a selection of chemical compounds. The research concerns five groups of esters, each with a different smell: almond, apricot, apple, pineapple and rose. The supposed relationship between the smell and certain selected attributes of each molecule was examined by various pattern recognition techniques using programs developed in the Department of Computer Chemistry at Rzeszów University of Technology.

  16. Studies on the Synthesis and the Structure of Ferric Aluminum Magnesium Hydrotalcite-like Compounds

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The particles of ferric aluminum magnesium hydrotalcite-like compounds (Fe-Al-Mg_HTlc) were synthesized by co-precipitation method. It was found that when n(Fe)/n(Al+Mg+Fe)0.30, Al(OH)3 will emerge; when the molar ratio of Fe/(Fe+Al+Mg) >0.30, the amorphous composition will appear. Hence Fe3+ and Al3+ have no concentration superposition effect on the crystal structure of the samples.

  17. The release of stored energy in heavily irradiated NaCl explosive reactions

    NARCIS (Netherlands)

    Vainshtein, D.; Bemt, M. van den; Seinen, J.; Datema, H.C.; Hartog, H.W. den

    1995-01-01

    During irradiation of NaCl with ionizing radiation at moderate temperatures (50-150 degrees C) irregular structures of very fine Na and Cl nano-precipitates are formed. The increase of the temperature to a value between 50 and 250 degrees C might induce explosive reactions between radiolytic Na and

  18. Predicting physical-chemical properties of compounds from molecular structures by recursive neural networks.

    Science.gov (United States)

    Bernazzani, Luca; Duce, Celia; Micheli, Alessio; Mollica, Vincenzo; Sperduti, Alessandro; Starita, Antonina; Tiné, Maria Rosaria

    2006-01-01

    In this paper, we report on the potential of a recently developed neural network for structures applied to the prediction of physical chemical properties of compounds. The proposed recursive neural network (RecNN) model is able to directly take as input a structured representation of the molecule and to model a direct and adaptive relationship between the molecular structure and target property. Therefore, it combines in a learning system the flexibility and general advantages of a neural network model with the representational power of a structured domain. As a result, a completely new approach to quantitative structure-activity relationship/quantitative structure-property relationship (QSPR/QSAR) analysis is obtained. An original representation of the molecular structures has been developed accounting for both the occurrence of specific atoms/groups and the topological relationships among them. Gibbs free energy of solvation in water, Delta(solv)G degrees , has been chosen as a benchmark for the model. The different approaches proposed in the literature for the prediction of this property have been reconsidered from a general perspective. The advantages of RecNN as a suitable tool for the automatization of fundamental parts of the QSPR/QSAR analysis have been highlighted. The RecNN model has been applied to the analysis of the Delta(solv)G degrees in water of 138 monofunctional acyclic organic compounds and tested on an external data set of 33 compounds. As a result of the statistical analysis, we obtained, for the predictive accuracy estimated on the test set, correlation coefficient R = 0.9985, standard deviation S = 0.68 kJ mol(-1), and mean absolute error MAE = 0.46 kJ mol(-1). The inherent ability of RecNN to abstract chemical knowledge through the adaptive learning process has been investigated by principal components analysis of the internal representations computed by the network. It has been found that the model recognizes the chemical compounds on the

  19. Saccharin: a lead compound for structure-based drug design of carbonic anhydrase IX inhibitors.

    Science.gov (United States)

    Mahon, Brian P; Hendon, Alex M; Driscoll, Jenna M; Rankin, Gregory M; Poulsen, Sally-Ann; Supuran, Claudiu T; McKenna, Robert

    2015-02-15

    Carbonic anhydrase IX (CA IX) is a key modulator of aggressive tumor behavior and a prognostic marker and target for several cancers. Saccharin (SAC) based compounds may provide an avenue to overcome CA isoform specificity, as they display both nanomolar affinity and preferential binding, for CA IX compared to CA II (>50-fold for SAC and >1000-fold when SAC is conjugated to a carbohydrate moiety). The X-ray crystal structures of SAC and a SAC-carbohydrate conjugate bound to a CA IX-mimic are presented and compared to CA II. The structures provide substantial new insight into the mechanism of SAC selective CA isoform inhibition.

  20. Structural stability and masnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    CHE XingLai; LI diaHao; DAI Ye; LIU BaiXin

    2009-01-01

    The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crys-talline structures, i.e. A15, D019, D03 and L12 Ni3Pt and NiPt3, and α-NiAs, B1, B2, L28, and L10 NiPt. The calculations reveal that the L12 Ni3Pt, L10 NiPt and L12 NiPt3 are energetically more stable than their respective competitive structures, indicating that the three structures may be formed in some appro-priate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states, which may signifi-cantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds.

  1. Structural stability and magnetism of metastable Ni-Pt intermetallic compounds studied by ab initio calculation

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The self-consistent electronic structure calculations were carried out with the accurate frozen-core full-potential projector augmented-wave method on 13 Ni-Pt intermetallic compounds of simple crystalline structures,i.e. A15,D019,D03 and L12 Ni3Pt and NiPt3,and α-NiAs,B1,B2,L2a,and L10 NiPt. The calculations reveal that the L12 Ni3Pt,L10 NiPt and L12 NiPt3 are energetically more stable than their respective competitive structures,indicating that the three structures may be formed in some appropriate conditions. The obtained results match well with the experimental observation or other theory predictions. It is found that there is hybridization between Ni 3d and Pt 5d states,which may significantly affect the structural stability and magnetism of metastable Ni-Pt intermetallic compounds.

  2. Disorder-induced structural transitions in topological insulating Ge-Sb-Te compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeongwoo; Jhi, Seung-Hoon, E-mail: jhish@postech.ac.kr [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2015-05-21

    The mechanism for the fast switching between amorphous, metastable, and crystalline structures in chalcogenide phase-change materials has been a long-standing puzzle. Based on first-principles calculations, we study the atomic and electronic properties of metastable Ge{sub 2}Sb{sub 2}Te{sub 5} and investigate the atomic disorder to understand the transition between crystalline hexagonal and cubic structures. In addition, we study the topological insulating property embedded in these compounds and its evolution upon structural changes and atomic disorder. We also discuss the role of the surface-like states arising from the topological insulating property in the metal-insulator transition observed in the hexagonal structure.

  3. Magnetic structure and physical properties of the multiferroic compound PrMn2O5

    Science.gov (United States)

    Doubrovsky, C.; André, G.; Bouquet, F.; Elkaim, E.; Li, M.; Greenblatt, M.; Foury-Leylekian, P.

    2012-06-01

    RMn2O5 (R=lanthanide, Bi, Y) multiferroic compounds are intensively studied for their potential application in the spintronic field. In these systems, the key issue is to understand the origin of the strong coupling between the ferroelectric and magnetic orders and to investigate the influence of the nature of the R ions in this coupling. While the phase diagram of RMn2O5 compounds with small R size is well established, this of large R size compounds is missing due to the lack of samples originating with difficulties of synthesis. We present in this paper the first investigation of the thermodynamic, structural and magnetic properties of high quality polycrystalline PrMn2O5 samples. Our work shows that PrMn2O5 presents two magnetic transitions corresponding to commensurate magnetic orderings. We also evidence a weak lattice effect coupled to the magnetic order. Our results point out that the physical properties of PrMn2O5 differ from those of the parent compounds with magnetic R ions.

  4. Synthesis and structural characterization of new inorganic–organic hybrid: arsenomolybdate compound with cytosinium cations

    Indian Academy of Sciences (India)

    Meriem Ayed; Brahim Ayed; Amor Haddad

    2015-02-01

    New organic–inorganic hybrid compound, with formula (C4H6N3O)6 [(HAsO4)2Mo6O19].7H2O, was prepared and characterized by IR and UV–visible spectroscopies and X-ray diffraction techniques. Thermal analysis was performed to study their thermal stability. The crystal structure of the title compound (triclinic, space group $P − 1$, = 2) was determined by X-ray diffraction. The compound contains the polyanion [(HAsO4)2Mo6O19]6−, which consists of the six molybdenum octahedral grouped into two parts consisting of four edge-sharing octahedral and two face-sharing octahedral, respectively, these two parts are connected by two corner-sharing O atoms to form a bent Mo6 ring. The polyanion framework derives from the Strandberg type and it is a new isomer. The cytosinium cations (Cyt+) are embedded in the channels and interact with the inorganic framework by way of N-H $\\cdots$ O and O-H $\\cdots$ O hydrogen bonds. Furthermore, the electrochemical property of this compound has been studied.

  5. Predicting Flash Point of Organosilicon Compounds Using Quantitative Structure Activity Relationship Approach

    Directory of Open Access Journals (Sweden)

    Chen-Peng Chen

    2014-01-01

    Full Text Available The flash point (FP of a compound is the primary property used in the assessment of fire hazards for flammable liquids and is amongst the crucial information that people handling flammable liquids must possess as far as industrial safety is concerned. In this work, the FPs of 236 organosilicon compounds were collected and used to construct a quantitative structure activity relationship (QSAR model for predicting their FPs. The CODESSA PRO software was adopted to calculate the required molecular descriptors, and 350 molecular descriptors were developed for each compound. A modified stepwise regression algorithm was applied to choose descriptors that were highly correlated with the FP of organosilicon compounds. The proposed model was a linear regression model consisting of six descriptors. This 6-descriptor model gave an R2 value of 0.9174, QLOO2 value of 0.9106, and Q2 value of 0.8989. The average fitting error and the average predictive error were found to be of 10.34 K and 11.22 K, respectively, and the average fitting error in percentage and the average predictive error in percentage were found to be of 3.30 and 3.60%, respectively. Compared with the known reproducibility of FP measurement using standard test method, these predicted results were of a satisfactory precision.

  6. Structural Characterization of Mg/Al hydrotalcite-like Compounds and their Thermal Stability

    Science.gov (United States)

    Zhang, Shuhua; Yang, Siyuan; Wang, Cheng; Liu, Weijun; Gu, Xiaodan; Gan, Wenjun; Xue, Xiaoyu

    2014-03-01

    Hydrotalcite-like compounds, repersented by the formula [M1-x 2 + Mx3+ (OH)2]Xx/n n - . nH2O (M2+ = Ni2+, Mg2+, Cu2+,etc; M3+ = Al3+, Fe3+, etc; Xn- = CO32- , NO3-,etc) possess the brucite-like layers [Mg(OH)2] with positive charge and anionic compounds in the interlayer to form neutral materials. Catalytic effects to decompose NOx from automobile exhaust were highly related with the difference of M2+ and thermal stability because the catylists locate are about 200 ~ 500°. In this paper, Mg-Al-Cu and Mg-Al-Ni hydrotalcite-like compounds were characterized by XRD and FT-IR spectra and the thermal stability were analyzed by TGA and DTA. Even though they both have the typical diffraction peaks of hydrotalcites, but their interlayer spaces are different. Some weak chemical bonds were observed to be formed in Mg-Al-Ni hydrotalcites by FT-IR. Mg-Al-Ni hydrotalcite-like compound degraded at lower temperature, by contrast, Mg-Al-Cu hydrotalcite has the better structural stablilty and thermal stability.

  7. Compound-fluidic electrospray:An efficient method for the fabrication of microcapsules with multicompartment structure

    Institute of Scientific and Technical Information of China (English)

    CHEN HongYan; ZHAO Yong; JIANG Lei

    2009-01-01

    Microcapsules with multiple compartments are of significant importance in many applications such as smart drug delivery,microreactor,complicated sensor,end so on. Here we report a novel compound-fluidic electrospray method that could fabricate multicompartment microcapsules in a single step. The as-prepared microcapsules have multiple compartments inside. The compartments are separated from each other by inner walls made from shell materials,and different content can be independently loaded in each of them without any contact. We assemble a hierarchical compound nozzle by inserting certain numbers of metallic inner capillaries separately into a blunt metal needle. The particular configuration of the compound nozzle induces a completely and independently envelope of core fluids by shell fluid,as a result of which mulicomponent microcapsules with multicompartment structure can be obtained. And also,the number of inner compartments and the corresponding encapsulated components can be controlled by rationally designing the configuration of the compound nozzle.This general method can be readily extended to many other functional materials,especially for the effective encapsulation of active ingredients,such as sensitive and reactive materials.

  8. Strukturna analiza složenih planetarnih prenosnika snage / Structural analysis of compound planetary gear trains

    Directory of Open Access Journals (Sweden)

    Slavko Muždeka

    2005-03-01

    Full Text Available Određivanje osnovnih kinematičkih i dinamičkih karakteristika složenih planetarnih prenosnika je složen proces za koji je razvijeno više analitičkih, grafičkih i grafoanalitičkih metoda. U radu je prikazan način određivanja prenosnog odnosa, opterećenja elemenata i tokova snage za planetarni red sa spoljašnjim i unutrašnjim ozubljenjem preko polužne analogije i primene strukturnog (Wolfovog simbola. Polužna analogija definisana je i za planetarni red sa spoljašnjim ozubljenjem, za koji je, takođe, definisan strukturni simbol. Definisani strukturni simboli iskorišćeni su za definisanje strukture prenosnika tipa Ravigneaux. Primena strukturne šeme za analizu karakteristika složenih planetarnih prenosnika ilustrovana je kroz analizu određenih funkcionalnih stanja planetarnih menjačkih prenosnika. Posebno je definisana mogućnost analize blokiranih stanja planetarnih menjačkih prenosnika. / Determination of basic cinematic and dynamic characteristics of compound planetary gear trains is complex process. Therefore there are many analytical, graphical and graphic-analytical methods. This paper presents method of determination gear ratios, loads and power flows for planetary gear set with the sun and ring gear by lever analogy with the application of Wolfs structural symbol. The lever analogy and structural symbols are also defined for the planetary gear set with two sun gears. Defined structural symbols are employed for definition of Ravigneaux gear structure. Application of structural schemes for an analysis of compound planetary gear trains is illustrated through analysis of certain planetary gearboxes functional state. The possibility of analysis of blocked compound planetary gear train is defined too.

  9. [Effects of Organic and Inorganic Slow-Release Compound Fertilizer on Different Soils Microbial Community Structure].

    Science.gov (United States)

    Wang, Fei; Yuan, Ting; Gu, Shou-kuan; Wang, Zheng-yin

    2015-04-01

    As a new style fertilizer, slow-control release fertilizer had been an important subject in recent years, but few researches were about soil microbial community structure diversity. Phospholipid fatty acid method was used to determined the microbial community structure diversity of acid soil and slight alkaline soil applied with slow-release compound fertilizer (SRF), chemical fertilizer (CF) and common compound fertilizer (CCF) at the 10th, 30th, 60th and 90th day under the constant temperature incubation condition. Results indicated that various bacteria (i. e 13:0, i14:0,14:0, i15:0, a15:0, i16:0, 16:12OH, 16:1w5c,16:0, i17:0, a17:0, cy17:0, 17:02OH, i18:0, 18:0 and cy19:0w8c), two actinomycetes (10Me17:0 and 10Me18:0) and only one fungus (18:1 w9c) were detected in two soils after applying slow-release compound fertilizer and other fertilizers during the whole incubation period. SRF could significantly increase the fungi PLFA content by 8.3% and 6.8% at the early stage (the 10th day and 30th day) compared with CF, as well as significantly increase by 22.7% and 17.1% at the late stage (the 60th day and 90th day) compared with CCF in acid soil. SRF significantly increased bacteria, fungi and gram positive bacteria compared with CF and CCF in incubation period (except at the 30th day) in slight alkaline soil. SRF could significantly improve the ratio of normal saturated fatty acid and monounsaturated fatty acid at the 30th day and 90th days in acid soil compared with no fertilizer (CK), CF and CCF, while as to slight alkaline soil, SRF was significantly greater than that of CK, CF and CCF only at the 60th day. SRF could significantly decrease the ratio of iso PLFA and anteiso PLFA in acid soil (in 30-90 days) and slight alkaline soil (in 10-60 days). For two soils PLFA varieties, contents and ratios of microbial community, slow-release compound fertilizer increased soil microbial PLFA varieties and contents, and decreased the influence to microbial survival

  10. Structural Characterization and Evaluation of the Antioxidant Activity of Phenolic Compounds from Astragalus taipaishanensis and Their Structure-Activity Relationship

    Science.gov (United States)

    Pu, Wenjun; Wang, Dongmei; Zhou, Dan

    2015-09-01

    Eight phenolic compounds were isolated using bio-guided isolation and purified from the roots of Astragalus taipaishanensis Y. C. Ho et S. B. Ho (A. taipaishanensis) for the first time. Their structures were elucidated by ESI-MS, HR-ESI-MS, 1D-NMR and 2D-NMR as 7,2‧-dihydroxy-3‧,4‧-dimethoxy isoflavan (1), formononetin (2), isoliquiritigenin (3), quercetin (4), kaempferol (5), ononin (6), p-hydroxybenzoic acid (7) and vanillic acid (8). Six flavonoids (compounds 1-6) exhibited stronger antioxidant activities (determined by DPPH, ABTS, FRAP and lipid peroxidation inhibition assays) than those of BHA and TBHQ and also demonstrated noticeable protective effects (particularly quercetin and kaempferol) on Escherichia coli under oxidative stress. Additionally, the chemical constituents compared with those of Astragalus membranaceus and the structure-activity relationship of the isolated compounds were both analyzed. The results clearly demonstrated that A. taipaishanensis has the potential to be selected as an alternative medicinal and food plant that can be utilized in health food products, functional tea and pharmaceutical products.

  11. Effects of Manganese Substitution in the Nd2Co17-xMnx Compounds on Structural and Magnetic Properties

    Institute of Scientific and Technical Information of China (English)

    HAO Yan-Ming; LI Yang-Xian; SUN He-Xu; QU Jing-Ping; GAO Yan; WANG Bo-Wen

    2001-01-01

    The structural and magnetic properties of the Nd2 Co17-x Mnx (x ≤ 14) compounds have been investigated bymeans of x-ray diffraction and magnetization measurements. The Nd2Co17-xMnx (x ≤ 14) compounds have arhombohedral Th2Znl7-type structure. The unit-cell volume increases with increasing x. The Curie temperatureand the saturation magnetization of these compounds show a marvellous drop with increasing x. The spin reorientation is observed at about 190 K in the Nd2Co15Mn2 compound.

  12. Infrared properties of doped and irradiated NaCl crystals

    Energy Technology Data Exchange (ETDEWEB)

    Izvekov, V.P.; Pungor, E. (Budapesti Mueszaki Egyetem (Hungary). Altalanos es Analitikai Tanszek); Gyoergyi, T.; Pungor, E. (Orszagos Frederic Joliot-Curie Sugarbiologiai es Sugaregeszseguegyi Kutato Intezet, Budapest (Hungary))

    1982-06-01

    Infrared spectra of X-ray irradiated NaCl crystals doped with Ca/sup 2 +/ and Sr/sup 2 +/ ions are presented. The localized modes of the hydrogen impurities in doped NaCl crystals and their changes induced by radiation have been studied.

  13. Electronic band structure of LaCoO{sub 3}/Y/Mn compounds

    Energy Technology Data Exchange (ETDEWEB)

    Rahnamaye Aliabad, H.A., E-mail: rahnama@sttu.ac.ir [Department of Physics, Hakim Sabzevari University, Sabzevar (Iran, Islamic Republic of); Hesam, V. [Department of Physics, Khayyam Institute of Higher Education, Mashhad (Iran, Islamic Republic of); Ahmad, Iftikhar; Khan, Imad [Department of Physics, University of Malakand, Chakdara (Pakistan)

    2013-02-01

    Spin polarization effects on electronic properties of pure LaCoO{sub 3} and doped compounds (La{sub 0.5}Y{sub 0.5}CoO{sub 3}, LaCo{sub 0.5}Mn{sub 0.5}O{sub 3}) in the rhombohedral phase have been studied. We have employed the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA+U) under density functional theory (DFT). The calculated band structures along with total as well as partial densities of states reveal that Y and Mn impurities have a significant effect on the structural and electronic properties of LaCoO{sub 3}. It is found that Mn alters insulating behavior of this compound to the half metallic for spin up state. Obtained results show that the magnetic moment for the Co-3d state is near 3.12{mu}{sub B} in LaCoO{sub 3} compound which increases and decreases with addition of Y and Mn dopants respectively.

  14. Structural, electronic, mechanical, and thermoelectric properties of a novel half Heusler compound HfPtPb

    Science.gov (United States)

    Kaur, Kulwinder; Rai, D. P.; Thapa, R. K.; Srivastava, Sunita

    2017-07-01

    We explore the structural, electronic, mechanical, and thermoelectric properties of a new half Heusler compound HfPtPb, an all metallic heavy element, recently proposed to be stable [Gautier et al., Nat. Chem. 7, 308 (2015)]. In this work, we employ density functional theory and semi-classical Boltzmann transport equations with constant relaxation time approximation. The mechanical properties, such as shear modulus, Young's modulus, elastic constants, Poisson's ratio, and shear anisotropy factor, have been investigated. The elastic and phonon properties reveal that this compound is mechanically and dynamically stable. Pugh's ratio and Frantsevich's ratio demonstrate its ductile behavior, and the shear anisotropic factor reveals the anisotropic nature of HfPtPb. The band structure predicts this compound to be a semiconductor with a band gap of 0.86 eV. The thermoelectric transport parameters, such as Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and lattice thermal conductivity, have been calculated as a function of temperature. The highest value of Seebeck coefficient is obtained for n-type doping at an optimal carrier concentration of 1.0 × 1020 e/cm3. We predict the maximum value of figure of merit (0.25) at 1000 K. Our investigation suggests that this material is an n-type semiconductor.

  15. Biocidal Compounds from Mentha sp. Essential Oils and Their Structure-Activity Relationships.

    Science.gov (United States)

    Kimbaris, Athanasios C; González-Coloma, Azucena; Andrés, Maria Fe; Vidali, Veroniki P; Polissiou, Moschos G; Santana-Méridas, Omar

    2017-03-01

    Essential oils from Greek Mentha species showed different chemical compositions for two populations of M. pulegium, characterized by piperitone and pulegone. Mentha spicata essential oil was characterized by endocyclic piperitenone epoxide, piperitone epoxide, and carvone. The bioactivities of these essential oils and their components have been tested against insect pests (Leptinotarsa decemlineata, Spodoptera littoralis and Myzus persicae), root-knot nematodes (Meloydogine javanica) and plants (Lactuca sativa, Lolium perenne, Solanum lycopersicum). The structure-activity relationships of these compounds have been studied including semi-synthetic endocyclic trans-carvone epoxide, exocyclic carvone epoxide, a new exocyclic piperitenone epoxide and trans-pulegone epoxide. Leptinotarsa decemlineata feeding was affected by piperitenone and piperitone epoxide. Spodoptera littoralis was affected by piperitone epoxide and pulegone. The strongest nematicidal agent was piperitenone epoxide, followed by piperitone epoxide, piperitenone and carvone. Germination of S. lycopersicum and L. perenne was significantly affected by piperitenone epoxide. This compound and carvone epoxide inhibited L. perenne root and leaf growth. Piperitenone epoxide also inhibited the root growth of S. lycopersicum. The presence of a C(1) epoxide resulted in strong antifeedant, nematicidal and phytotoxic compounds regardless of the C(4) substituent. New natural crop protectants could be developed through appropriate structural modifications in the p-menthane skeleton. © 2017 Wiley-VHCA AG, Zurich, Switzerland.

  16. Effect of compound organification of montmorillonite on the structure and properties of polypropylene/montmorillonite nanocomposites

    Institute of Scientific and Technical Information of China (English)

    HONG Haoqun; JIA Demin; HE Hui

    2007-01-01

    In this paper,reactive organic montmorillonite (RMMT),prepared with compound alkylammoniums,were used in ternary-monomer solid phase graft copolymerization in order to enhance the melting intercalation of montmoril-lonite (MMT),stabilize the intercalated structure,and prepare the exfoliated polypropylene/montrnorillonite (PP/MMT) nanocomposites (PPMN).The structure and properties of PPMN were studied by X-ray diffraction (XRD),Fourier transform infrared spectroscopy (FTIR),transmission elec-tron microscope (TEM),etc.Results show that the compound organification,solid phase graft copolymerization really favored the melting intercalation.The compound organifica- tion and exothermic process of the solid phase copolymeriza-tion promoted the melting intercalation.The mechanical properties,melt flow rate and Vicat softening point of PPMN significantly had a preferable reinforced state at 6-8 phr PP/MMT graft copolymers (PPGM).The increase of the mechanical properties and thermal properties was owed to the reinforcement of the exfoliated MMT and the compatibiliza-tion of the oligomers built by the polar monomers during the solid phase graft copolymerization.The improvement of the fluidity of PPMN derived from the plasticization of the exfoliated MMT and oligomers.

  17. Synthesis, Structure and Biological Activities of Novel Triazole Compounds Containing Thioamide Group

    Institute of Scientific and Technical Information of China (English)

    刘法谦; 秦永其; 许良忠; 陆路德; 杨绪杰; 汪信

    2005-01-01

    Two compounds 2-benzoyl-N-phenyl-2-( 1,2,4-triazol- 1-yl)thioacetamide (1) and 2-(4-chlorobenzoyl)-N-phenyl-2-(1,2,4-triazol-1-yl)thioacetamide (2) were synthesized from substituted acetophenone, triazole and phenyl isothiocyanate by several step reactions. The structure of compound 1 was determined by single-crystal X-ray diffraction analysis. It crystallizes in monoclinic system with space group P21/c, a =0.8806(2) nm, b= 1.2097(2) nm, c= 1.4809(3) nm, β=105.88°, Z=4, V=1.5173(6) nm3, Dc= 1.411 Mg/m3, μ=0.22 mm-1, F(000)=672, final R1=0.040 and Rw=0.103. There is obvious potentially weak C—H…N intermolecular interaction in the crystal, which stabilizes the structure. The results of biological test show that the two compounds have antifungal and plant growth regulating activities.

  18. Electronic band structure of LaCoO3/Y/Mn compounds

    Science.gov (United States)

    Rahnamaye Aliabad, H. A.; Hesam, V.; Ahmad, Iftikhar; Khan, Imad

    2013-02-01

    Spin polarization effects on electronic properties of pure LaCoO3 and doped compounds (La0.5Y0.5CoO3, LaCo0.5Mn0.5O3) in the rhombohedral phase have been studied. We have employed the full potential linearized augmented plane wave (FP-LAPW) method with the generalized gradient approximation (GGA+U) under density functional theory (DFT). The calculated band structures along with total as well as partial densities of states reveal that Y and Mn impurities have a significant effect on the structural and electronic properties of LaCoO3. It is found that Mn alters insulating behavior of this compound to the half metallic for spin up state. Obtained results show that the magnetic moment for the Co-3d state is near 3.12μB in LaCoO3 compound which increases and decreases with addition of Y and Mn dopants respectively.

  19. Structural, electronic, and elastic properties of K-As compounds: a first principles study.

    Science.gov (United States)

    Ozisik, Havva Bogaz; Colakoglu, Kemal; Deligoz, Engin; Ozisik, Haci

    2012-07-01

    First-principle calculations are performed to investigate the structural, elastic and electronic properties of K-As compounds (KAs in NaP, LiAs and AuCu-type structures, KAs(2) in MgCu(2)-type structure, K(3)As in Na(3)As, Cu(3)P and Li(3)Bi-type structures, and K(5)As(4) in A(5)B(4)-type structure). The lattice parameters, cohesive energy, formation energy, bulk modulus, and the first derivative of bulk modulus (to fit to the Murnaghan's equation of state) of the considered structures are calculated and reasonable agreement is obtained, and the phase transition pressure is also predicted. The repeated calculations on the electronic band structures and the related partial density of states are also given. The calculated second-order elastic constants based on the stress-strain method and the other related quantities such as Young's modulus, shear modulus, Poisson's ratio, sound velocities, Debye temperature, and shear anisotropy factors for considered structures are presented, and trends are discussed.

  20. Spectral characteristics of heterocyclic compounds with a chain structure, cooled in an ultrasonic jet

    Science.gov (United States)

    Povedailo, V. A.; Yakovlev, D. L.

    2006-11-01

    We have recorded the fluorescence excitation spectra of three heterocyclic compounds with a chain structure [BPO (2-phenyl-5-(4-diphenylyl)oxazole), POPOP (1,4-di[2-(5-phenyloxazolyl)]benzene, and TOPOT (1,4-di[2-(5-n-tolyloxazolyl)]benzene] and the fluorescence spectra of POPOP, under conditions where the molecules were cooled in an ultrasonic helium jet. A line structure is observed in the spectra of POPOP and TOPOT; for the BPO molecules, whose configuration changes considerably during electronic excitation, vibrational structure is apparent only in the low-frequency region of the excitation spectrum, and a diffuse spectrum is recorded starting from ν 0 0 + 200 cm-1. For all the compounds, in the spectra we recorded vibrations with frequencies up to 100 cm-1, arising due to the flexibility of the molecular structure. The rotational contours of the lines for the electronic and vibronic transitions of the POPOP molecules (Trot = 10.5 K) and TOPOT molecules (Trot = 15 K) are structureless and bell-shaped. The degree of polarization of the fluorescence Pfl for the jet-cooled POPOP molecules for excitation of vibrations along the absorption band up to 2000 cm-1 above ν 0 0 is practically constant (˜8.4%) and matches Pfl for high-temperature vapors.

  1. Thermal and structural study on the lattice compound 1,4-diammoniumbutane bis(theophyllinate)

    Energy Technology Data Exchange (ETDEWEB)

    Ban, Margit; Madarasz, Janos; Bombicz, Petra; Pokol, Gyoergy; Gal, Sandor

    2004-10-01

    Crystalline title compound (1) prepared from aqueous solution of theophylline and 1,4-diaminobutane has been structurally and thermally characterized. Both the two-step TG decomposition curve and elemental analysis of the hexagonal crystals show that it consists of theophylline and 1,4-diaminobutane in 2:1 molar ratio. Actually, presence of one type of both theophyllinate anions and 1,4-diammoniumbutane dication have been indicated by FTIR spectroscopy. The molecular structure of lattice compound (1) has been determined by single crystal X-ray diffraction, where the hydrogen positions have been obtained from differential Fourier maps. It has confirmed that the crystal is really built up from these ionic constituents bound together with an extensive net of hydrogen bonds. The coupled TG-FTIR analysis of the evolved gases has revealed that the diamine is released as a whole molecule in the first decomposition step. Clathrate 1 and the proton migration in it might serve as a structural model of solid aminophylline whose crystal structure is still unknown.

  2. Synthesis, Structure and Biological Activities of Novel Triazole Compounds Containing N,N-Dialkyldithiocarbamate Moiety

    Institute of Scientific and Technical Information of China (English)

    XU,Liang-Zhong(许良忠); JIAN,Fang-Fang(建方方); SHI,Jian-Gang(时建刚); SUN,Ping-Ping(孙萍萍); JIAO,Kui(焦奎)

    2004-01-01

    The two compounds, 2,2-dimethyl-4-S-(N,N-dimethyldithiocarbamato)-5-(1,2,4-triazol-1-yl)-propione (1) and 2,2-dimethyl-4-S-(N,N-diethyldithiocarbamato)-5-(1,2,4-triazol-1-yl)-3-propione (2), were prepared by reacting N,N-dialkyldithiocarbamate sodium with 2,2-dimethyl-4-bromo-5-(1,2,4-triazol-1-yl)-propione. Their structures were identified by elemental analysis, IR and 1H NMR spectroscopy. The structure of 1 has been determined by X-ray single crystal structure analysis. It crystallizes in monoclinic system with space group P21/c, a= 1.2315(3)nm, b =1.2057(2) nm, c=1.2532(3) nm, β=118.55(3)° Z=4, V= 1.6345(6) nm3, Dc= 1.221 g/cm3, μ=0.324 mm -1, F(000)=640, final R1 =0.0449. There is obvious potentially weak C-H…N intermolecular interaction in the crystal, which stabilizes the crystal structure. The result of the biological test showed that the two compounds have fungistasis and plant growth regulating activities.

  3. Topological aspects of lanthanide-adipate-aqua compounds: Close packed and open framework structures

    Science.gov (United States)

    Chowdhuri, Durga Sankar; Kumar Jana, Swapan; Hazari, Debdoot; Zangrando, Ennio; Dalai, Sudipta

    2013-07-01

    A search in the Cambridge Structural Database (CSD) for lanthanide complexes with adipate [OOC(CH2)4COO]2- and aqua ligands retrieved a fair number of compounds. To this dataset a new lanthanum metal-organic framework, {[La2(adip)3(H2O)2] (1) (adipH2=adipic acid), synthesised and structurally characterized in these labs, was included. The crystal structures of these coordination polymers, of general formulation [Ln2(adip)3(H2O)x], exhibit a variety of topologies and dimensionality, which were clustered in different classes and described in detail. It was explored that the majority of these evidences the presence of metal chains or dinuclear Ln2 entities (separated in both cases by 4.0-4.8 Å), where lanthanide ions are differently connected by carboxylate groups with chelating or oxygen-bridging mode. The different amount of coordinated water molecules appear to affect the solid state networks. Moreover the crystal packing of these compounds shows peculiar aspects and examples were reported in the literature where the long alkyl chain of adipate connectors give rise to interpenetrated structures, or to porous material where lattice water or neutral larger molecules are clathrated.

  4. Syntheses, Crystal Structures and Fluorescent Properties of Two New Imidazolidino Schiff Base Compounds

    Institute of Scientific and Technical Information of China (English)

    FENG Yue; LIU Gang; TIAN Xiu-Mei; WANG Ji-De; WANG Wei

    2008-01-01

    Two new imidazolidino Schiff base compounds, (E)-N-((quinoxalin-2-yl)methylene)-2-(2-(quinoxalin-3-yl)imidazolidin-1-yl)ethanamine 1 and 2-(1-(2-(2-(quinoxalin-3-yl)imidazolidin-1-yl)ethyl)imidazolidin-2-yl)quinoxaline 2, have been synthesized and characterized by elemental analysis,1H NMR, IR, MS and single-crystal X-ray diffraction. Crystallographic data for 1: C22H21N7,Mr = 383.46, monoclinic, space group P21, a = 7.0036(14), b=6.9151(14), c=19.701(4)(A),β=96.57(3)°, Z = 2, V=947.9(3)(A)3, Dc = 1.344 g/cm3, F(000)=404, μ = 0.085 mm-1, Flack parameter =0(2), R = 0.0464 and wR = 0.1055; and those for 2: C24H26N8, Mr = 426.53, triclinic, space group P(1),a = 9.6680(19), b = 10.334(2), c = 11.389(2)(A),α= 104.12(3),β= 102.95(3),γ= 100.48(3)°, Z=2,V=1041.2(4)(A)3, Dc=1.361 g/cm3, F(000) = 452,μ = 0.086 mm-1, R = 0.0373 and wR = 0.1155. For the two compounds, the five-membered imidazolidine rings all adopt envelope conformation.Moreover, the title compounds show one-dimensional layered and three-dimensional supramolecular chainlike structures, respectively. Fluorescent properties of the two compounds have been investigated in the solid state at room temperature. Compound 1 exhibits strong fluorescence and thus may serve as excellent candidates of green fluorescent materials.

  5. Structural Feature and Solute Trapping of Rapidly Grown Ni3Sn Intermetallic Compound

    Institute of Scientific and Technical Information of China (English)

    QIN Hai-Yan; WANG Wei-Li; WEI Bing-Bo

    2009-01-01

    The rapid dendritic growth of primary Ni3Sn phase in undercooled Nio30.9%Sn-5%Ge alloy is investigated by using the glass fluxing technique. The dendritic growth velocity of Ni3Sn compound is measured as a function of undercooling, and a velocity of 2.47m/s is achieved at the maximum undercooling of 251 K (0.17TL). The addition of the Ge element reduces its growth velocity as compared with the binary Ni75Sn25 alloy. During rapid solidification, the Ni3Sn compound behaves like a normal sofid solution and it displays a morphological transition of "coarse dendrite-equiaxed grain-vermicular structure" with the increase of undercooling. Significant solute trapping of Ge atoms occurs in the whole undercooling range.

  6. Structural Characterization and Infrared and Electrical Properties of the New Inorganic-Organic Hybrid Compound

    Directory of Open Access Journals (Sweden)

    A. Oueslati

    2013-01-01

    Full Text Available New inorganic-organic hybrid [(C3H74N]2Hg2Cl6 compound was obtained and characterised by single-crystal X-ray diffraction, infrared, and impedance spectroscopy. The latter crystallizes in the monoclinic system (space group C 2/c, with the following unit cell dimensions: (1 Å, (6 Å, (2 Å, and (2. Besides, its structure was solved using 84860 independent reflections leading to . Electrical properties of the material were studied using impedance spectroscopic technique at different temperatures in the frequency range of 209 Hz to 5 MHz. Detailed analysis of the impedance spectrum suggested that the electrical properties of the material are strongly temperature-dependent. The Nyquist plots clearly showed the presence of bulk and grain boundary effect in the compound.

  7. Quantitative Structure Activity Relationship of Cinnamaldehyde Compounds against Wood-Decaying Fungi

    Directory of Open Access Journals (Sweden)

    Dongmei Yang

    2016-11-01

    Full Text Available Cinnamaldehyde, of the genius Cinnamomum, is a major constituent of the bark of the cinnamon tree and possesses broad-spectrum antimicrobial activity. In this study, we used best multiple linear regression (BMLR to develop quantitative structure activity relationship (QSAR models for cinnamaldehyde derivatives against wood-decaying fungi Trametes versicolor and Gloeophyllun trabeum. Based on the two optimal QSAR models, we then designed and synthesized two novel cinnamaldehyde compounds. The QSAR models exhibited good correlation coefficients: R2Tv = 0.910 for Trametes versicolor and R2Gt = 0.926 for Gloeophyllun trabeum. Small errors between the experimental and calculated values of two designed compounds indicated that these two QSAR models have strong predictability and stability.

  8. Electronic structure and electric field gradient calculations for the Zr{sub 2}Ni intermetallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Umicevic, A.; Belosevic-Cavor, J.; Koteski, V.; Cekic, B.; Ivanovski, V. [Inst. of Nuclear Sciences Vinca, Lab. for Nuclear and Plasma Physics, Belgrade (Yugoslavia)

    2009-09-15

    A detailed theoretical study of the structure and electric field gradients (EFG) of the Zr{sub 2}Ni compound is presented. Using all-electron augmented plane waves plus local orbitals formalism, the equilibrium volume, bulk modulus, and EFGs at both non-equivalent crystallographic positions, Zr and Ni, are calculated. The possible mechanism of formation of the EFGs at both sites are analyzed and discussed. We have also performed supercell calculations with Cd and Ta impurities. Through the comparison of theoretical and experimental EFGs in these cases, we elucidate the role played by the Cd and Ta probe atoms in the time-differential perturbed angular correlation measurements of this compound. (orig.)

  9. Structural, mechanical and thermodynamic properties of N-dope BBi compound under pressure

    Science.gov (United States)

    Yalcin, Battal G.

    2016-04-01

    The structural, mechanical and thermodynamic properties of N-dope BBi compound have been reported in the current study. The structural and mechanical results of the studied binary compounds (BN and BBi) and their ternary alloys BBi1- x N x structures are presented by means of density functional theory. The exchange and correlation effects are taken into account by using the generalized gradient approximation functional of Wu and Cohen which is an improved form of the most popular Perdew-Burke-Ernzerhof. The quasi-harmonic Debye model is used for the thermodynamic properties of studied materials. The basic physical properties of considered structures such as the equilibrium lattice parameter (a 0), bulk modulus (B 0), its pressure derivative (B'), elastic constants (C 11, C 12 and C 44), Kleinman's internal-strain parameter (ƺ), shear modulus anisotropy (A), the average shear modulus (G), Young's modulus (Y) and Poisson's ratio (v), B 0/ G ratio, microhardness parameter (H), Cauchy pressure (C″), and 1st and 2nd Lame constants (λ, μ), debye temperature (θ D), wave velocities (ν l, ν t and ν m), melting temperature (T m) and minimum thermal conductivity (κ min) have been calculated at zero pressure. In order to obtain more information, thermodynamic properties, such as internal energy (U), Helmoltz free energy (F), entropy (S), Debye temperature (θ D), thermal expansion (α), constant volume and pressure heat capacities (C V and C P ), are analyzed under the whole range from 0 to 20 GPa and temperature range from 0 to 1500 K. The obtained results of the studied binary compounds are in coincidence with experimental works.

  10. Synthesis, structure, and superconductivity in the new-structure-type compound: SrPt6P2.

    Science.gov (United States)

    Lv, Bing; Jawdat, BenMaan I; Wu, Zheng; Sorolla, Maurice; Gooch, Melissa; Zhao, Kui; Deng, Liangzi; Xue, Yu-Yi; Lorenz, Bernd; Guloy, Arnold M; Chu, Ching-Wu

    2015-02-02

    A metal-rich ternary phosphide, SrPt(6)P(2), with a unique structure type was synthesized at high temperatures. Its crystal structure was determined by single-crystal X-ray diffraction [cubic space group Pa3̅; Z = 4; a = 8.474(2) Å, and V = 608.51(2) Å(3)]. The structure features a unique three-dimensional anionic (Pt(6)P(2))(2-) network of vertex-shared Pt(6)P trigonal prisms. The Sr atoms occupy a 12-coordinate (Pt) cage site and form a cubic close-packed (face-centered-cubic) arrangement, and the P atoms formally occupy tetrahedral interstices. The metallic compound becomes superconducting at 0.6 K, as evidenced by magnetic and resistivity measurements.

  11. Structural, atomic Hirschfeld surface, magnetic and magnetocaloric properties of SmNi{sub 5} compound

    Energy Technology Data Exchange (ETDEWEB)

    Nouri, K., E-mail: nouri@icmpe.cnrs.fr [C.M.T.R, I.C.M.P.E, CNRS, Université Paris Est Créteil, UMR 7182, 2-8 rue Henri Dunant, F-94320 Thiais (France); Laboratoire des Sciences des Matériaux et de l' Environnement, Faculté des Sciences de Sfax- Université de Sfax, BP 1171, Sfax, 3018 (Tunisia); Jemmali, M. [Laboratoire des Sciences des Matériaux et de l' Environnement, Faculté des Sciences de Sfax- Université de Sfax, BP 1171, Sfax, 3018 (Tunisia); Chemistry Departement, College of Science and Arts at Ar-Rass, Qassim University, P.O. Box53 (Saudi Arabia); Walha, S. [Laboratoire des Sciences des Matériaux et de l' Environnement, Faculté des Sciences de Sfax- Université de Sfax, BP 1171, Sfax, 3018 (Tunisia); Zehani, K. [C.M.T.R, I.C.M.P.E, CNRS, Université Paris Est Créteil, UMR 7182, 2-8 rue Henri Dunant, F-94320 Thiais (France); Ben Salah, A. [Laboratoire des Sciences des Matériaux et de l' Environnement, Faculté des Sciences de Sfax- Université de Sfax, BP 1171, Sfax, 3018 (Tunisia); Bessais, L. [C.M.T.R, I.C.M.P.E, CNRS, Université Paris Est Créteil, UMR 7182, 2-8 rue Henri Dunant, F-94320 Thiais (France)

    2016-07-05

    The SmNi{sub 5} intermetallic compound has been investigated by arc-melting. Powder X-ray diffraction analysis and Rietveld refinement revealed that the sample crystallized in the hexagonal CaCu{sub 5}-type structure P6/mmm space group with the following lattice parameters: a = 4.9203 (1) Å, c = 3.9662 (1) Å. These lattice parameters for the compound are in good agreement with previous theoretical result and experimental data. The EDX analysis has been performed to confirm the composition of this compound. The chemical bonding in SmNi{sub 5} was analyzed using atomic Hirshfeld surfaces, and this analysis supports the presence of the structural elements and the coordination of Sm (1a), Ni (2c) and Ni (3 g). This study indicates the different types of interatomic interactions between the Sm and Ni atoms and the weak interactions between Sm–Sm atoms were also observed along the c axis. The magnetic properties and magnetocaloric effect (MCE) have been established by the magnetization and isothermal magnetization of different temperature measurements. The magnetization curve as a function of temperature shows a magnetic transition from ferromagnetic to paramagnetic state at the Curie temperature T{sub C} = 29 K. We have studied the MCE phenomena in the vicinity of magnetic phase transitions in terms of magnetic entropy change. The temperature dependence of the magnetization, the magnetic entropy changeΔS{sub M}, as well as the relative cooling power around the second-order magnetic transition and the Arrott plots for the alloys are reported. - Highlights: • The SmNi{sub 5} intermetallic compound has been investigated by arc-melting. • The chemical bonding in SmNi{sub 5} was analyzed using atomic Hirshfeld surfaces. • The second order magnetocaloric material SmNi{sub 5} is investigated.

  12. Synthesis, structural characterization, and anticancer activity of a monobenzyltin compound against MCF-7 breast cancer cells

    Directory of Open Access Journals (Sweden)

    Fani S

    2015-11-01

    Full Text Available Somayeh Fani,1 Behnam Kamalidehghan,1 Kong Mun Lo,2 Najihah Mohd Hashim,1 Kit May Chow,2 Fatemeh Ahmadipour1 1Department of Pharmacy, Faculty of Medicine, 2Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia Abstract: A new monoorganotin Schiff base compound, [N-(3,5-dichloro-2-oxidobenzylidene-4-chlorobenzyhydrazidato](o-methylbenzylaquatin(IV chloride, (compound C1, was synthesized, and its structural features were investigated by spectroscopic techniques and single-crystal X-ray diffractometry. Compound C1 was exposed to several human cancer cell lines, including breast adenocarcinoma cell lines MCF-7 and MDA-MB-231, ovarian adenocarcinoma cell lines Skov3 and Caov3, and prostate cancer cell line PC3, in order to examine its cytotoxic effect for different forms of cancer. Human hepatic cell line WRL-68 was used as a normal cell line. We concentrated on the MCF-7 cell line to detect possible underlying mechanism involvement of compound C1. 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay revealed the strongest cytotoxicity of compound C1 against MCF-7 cells, with a half maximal inhibitory concentration (IC50 value of 2.5±0.50 µg/mL after 48 hours treatment. The IC50 value was >30 µg/mL in WRL-68 cells. Induced antiproliferative activity of compound C1 for MCF-7 cells was further confirmed by lactate dehydrogenase, reactive oxygen species, acridine orange/propidium iodide staining, and DNA fragmentation assays. A significant increase of lactate dehydrogenase release in treated cells was observed via fluorescence analysis. Luminescent analysis showed significant growth in intracellular reactive oxygen species production after treatment. Morphological changes of necrosis and early and late apoptosis stages were observed in treated cells after staining with acridine orange/propidium iodide. DNA fragmentation was observed as a characteristic of apoptosis in treated cells. Results of the

  13. Electronic structure and thermodynamic properties of Cu3V2O8 compound

    Science.gov (United States)

    Jezierski, Andrzej; Kaczkowski, Jakub

    2015-10-01

    The electronic structure and thermodynamic properties of Cu3V2O8 compound for three structures (P-1, P21/c and Cmca) are reported. The calculations are performed by using full-potential local orbital minimum basis method. The total electronic densities of states for all structures have the similar shape but the details are different. The thermodynamic properties (the bulk modulus B, Gibbs free energy, Debye temperature ΘD) are calculated in quasiharmonic Debye-Grüneisen model using the equation of states in the form of Murnaghan, Birch-Murnaghan, Poirier-Tarantola and Vinet. Our ab initio results indicate that α(P-1) phase is stable below 839 K, β(P21/c) and γ(Cmca) phases can exist in the region of 839 K < T < 875 K, however above T = 875 K only γ(Cmca) phase is observed.

  14. Ab initio structure determination of new compound Ba 3(BO 3)(PO 4)

    Science.gov (United States)

    Ma, H. W.; Liang, J. K.; Wu, L.; Liu, G. Y.; Rao, G. H.; Chen, X. L.

    2004-10-01

    The crystal structure of new compound Ba3BPO7 was determined by ab initio method from high-resolution conventional X-ray powder diffraction data. The Rietveld refinement converged to Rp=5.92%, Rwp=8.87%, Rexp=5.00% with the following details: Hexagonal, space group P63mc, a=5.4898 (1) Å, c=14.7551(1) Å, Z=2. The basic unit of the structure is the [BaO10]-[BO3]-[PO4] polar polyhedra-chain composed of Ba1-B-P-O cluster. These chains, running along c-axis, stack in a HCP mode to build the whole structure with triangular prism channels. The channels are parallel to c-axis too, in which Ba2 and Ba3 are located.

  15. Structures of rare earth-transition metal rich compounds derived from CaCu5 type

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The properties of materials have a close connect ion to their crystal structures. Rare earth (R)-transition metal (T) rich compo und are the focus of investigation in the search for new hard magnetic materials . As the basis for the study of stabilized effect of the third component on the fo rmation of RT5 derivative and its influence of the occupied sites on magnetic properties, in this paper, the possible derivative compounds based on the RT5 primitive unit cell of the CaCu5 structure type formed through the ordered or disordered substitution of dumbbell pair 2T atoms for the R atoms at some sit es, and the structural relationship between the derivatives and the prototype ar e summarized.

  16. Formation, structure, and properties of "welded" h-BN/graphene compounds

    Science.gov (United States)

    Chernozatonskii, L. A.; Demin, V. A.; Artyukh, A. A.

    2016-07-01

    Structures of h-BN/graphene with holes where atoms at the edges are bonded to each other by sp 2 hybridized C-B and C-N bonds and form continuous junctions from layer to layer with topological defects inside holes have been considered. Their formation, as well as the moiré-type stable atomic structure of such compounds (with different rotation angles of graphene with respect to the hexagonal boron nitride monolayer) with closed hexagonal holes in the AA centers of packing of the moiré superlattice, has been studied. The stability, as well as the electronic and mechanical properties, of such bilayer BN/graphene nanomeshes has been analyzed within electron density functional theory. It has been shown that they have semiconducting properties. Their electronic band structures and mechanical characteristics differ from the respective properties of separate monolayer nanomeshes with the same geometry and arrangement of holes.

  17. Band structure of Heusler compounds studied by photoemission and tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arbelo Jorge, Elena

    2011-07-01

    Heusler compounds are key materials for spintronic applications. They have attracted a lot of interest due to their half-metallic properties predicted by band structure calculations. The aim of this work is to evaluate experimentally the validity of the predictions of half metallicity by band structure calculations for two specific Heusler compounds, Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa. Two different spectroscopy methods for the analysis of the electronic properties were used: Angular Resolved Ultraviolet Photoemission Spectroscopy (ARUPS) and Tunneling Spectroscopy. Heusler compounds are prepared as thin films by RF-sputtering in an ultra high vacuum system. For the characterization of the samples, bulk and surface crystallographic and magnetic properties of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa are studied. X-ray and electron diffraction reveal a bulk and surface crossover between two different types of sublattice order (from B2 to L2{sub 1}) with increasing annealing temperature. X-ray magnetic circular dichroism results show that the magnetic properties in the surface and bulk are identical, although the magnetic moments obtained are 5 % below from the theoretically predicted. By ARUPS evidence for the validity of the predicted total bulk density of states (DOS) was demonstrated for both Heusler compounds. Additional ARUPS intensity contributions close to the Fermi energy indicates the presence of a specific surface DOS. Moreover, it is demonstrated that the crystallographic order, controlled by annealing, plays an important role on broadening effects of DOS features. Improving order resulted in better defined ARUPS features. Tunneling magnetoresistance measurements of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa based MTJ's result in a Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} spin polarization of 44 %, which is the highest experimentally obtained value for this compound, although it is lower than the 100 % predicted. For Co

  18. PURY: a database of geometric restraints of hetero compounds for refinement in complexes with macromolecular structures.

    Science.gov (United States)

    Andrejasic, Miha; Praaenikar, Jure; Turk, Dusan

    2008-11-01

    The number and variety of macromolecular structures in complex with ;hetero' ligands is growing. The need for rapid delivery of correct geometric parameters for their refinement, which is often crucial for understanding the biological relevance of the structure, is growing correspondingly. The current standard for describing protein structures is the Engh-Huber parameter set. It is an expert data set resulting from selection and analysis of the crystal structures gathered in the Cambridge Structural Database (CSD). Clearly, such a manual approach cannot be applied to the vast and ever-growing number of chemical compounds. Therefore, a database, named PURY, of geometric parameters of chemical compounds has been developed, together with a server that accesses it. PURY is a compilation of the whole CSD. It contains lists of atom classes and bonds connecting them, as well as angle, chirality, planarity and conformation parameters. The current compilation is based on CSD 5.28 and contains 1978 atom classes and 32,702 bonding, 237,068 angle, 201,860 dihedral and 64,193 improper geometric restraints. Analysis has confirmed that the restraints from the PURY database are suitable for use in macromolecular crystal structure refinement and should be of value to the crystallographic community. The database can be accessed through the web server http://pury.ijs.si/, which creates topology and parameter files from deposited coordinates in suitable forms for the refinement programs MAIN, CNS and REFMAC. In the near future, the server will move to the CSD website http://pury.ccdc.cam.ac.uk/.

  19. Optical properties and electronic structure of BiTeCl and BiTeBr compounds

    Science.gov (United States)

    Makhnev, A. A.; Nomerovannaya, L. V.; Kuznetsova, T. V.; Tereshchenko, O. E.; Kokh, K. A.

    2016-09-01

    Optical properties of BiTeCl and BiTeBr compounds with a strong Rashba spin-orbit coupling are studied in the 0.08-5.0 eV range using the optical ellipsometry method. Fundamental characteristics of the electronic structure are obtained. Similarly to BiTeI, spectra of the imaginary part of dielectric permittivity constant ɛ2( E) in the energy interval between the plasma edge and the threshold of an intense interband absorption (0.7 eV in BiTeCl and 0.6 eV in BiTeBr) display a fine structure of electronic transitions at 0.25 and 0.55 eV in BiTeCl and 0.20 and 0.50 eV in BiTeBr. These features are assigned to electronic transitions between the bulk conduction zones split by the Rashba spin-orbit interaction. The parameters of the electronic structure of BiTeCl and BiTeBr are compared with the BiTeI compound that was studied earlier. In the BiTeCl-BiTeBr-BiTeI row, the absorption edge and main features of the fundamental absorption exhibit a shift to low energies.

  20. Pore structure modification of cement concretes by impregnation with sulfur-containing compounds

    Directory of Open Access Journals (Sweden)

    YANAKHMETOV Marat Rafisovich

    2015-02-01

    Full Text Available The authors study how the impregnation with sulfur-containing compounds changes the concrete pore structure and how it influences on the water absorption and watertightness. The results of this research indicate that impregnation of cement concrete with water-based solution of polysulphide modifies pore structure of cement concrete in such a way that it decreases total and effective porosity, reduces water absorption and increases watertightness. The proposed impregnation based on mineral helps to protect for a long time the most vulnerable parts of buildings – basements, foundations, as well as places on the facades of buildings exposed to rain, snow and groundwater. Application of the new product in the construction industry can increase the durability of materials, preventing the destruction processes caused by weathering, remove excess moisture in damp basements. The surfaces treated by protective compounds acquire antisoiling properties for a long time, and due to reduced thermal conductivity the cost of heating buildings is decreased. The effectiveness of the actions and the relatively low cost of proposed hydrophobizator makes it possible to spread widely the proposed protection method for building structures.

  1. Molecular structure of two gastrokinetic compounds, cisapride and R53757: comparison with dopaminergic D 2 antagonists

    Science.gov (United States)

    Collin, S.; Vercauteren, D. P.; Evrard, G.; Durant, F.; Tollenaere, J. P.; Moereels, H.

    1989-12-01

    The crystal structures of the title compounds have been solved by direct methods from single crystal X-ray diffraction. Cisapride: monoclinic, space group P2 1/ n with a=34.210(4), b=7.642(2), c=9.435(1) Å, β=90.93(1)°, Z=4, final R factor=0.044 for 1178 observed reflections. R53757: monoclinic, space group P2 1/ n with a=28.896(3), b=8.054(2), c=10.957(2) Å, β=91.79(1)°, Z=4, final R factor=0.032 for 933 observed reflections. Cisapride, a non-dopamine blocking gastrokinetic, and its closely related analog, R53757, are compared to two very potent D 2 antagonists, tropapride and R48788. The analysis of the X-ray determined structures completed by theoretical conformational studies suggests that the structural requirements for all compounds studied seem to be very similar. As shown by PCILO calculations, the presence of a methoxy group on the cisapride piperidine ring does not prevent an optimal orientation of the three putative pharmacophoric elements described for the D 2 receptor. Only the nature of the nitrogen lateral chain differs between the D 2 antagonists and cisapride.

  2. High-pressure structural stability of the ductile intermetallic compound, ErCu

    Indian Academy of Sciences (India)

    S Meenakshi

    2014-10-01

    High-pressure angle dispersive X-ray diffraction measurements up to 23.6 GPa have been carried out on the ductile intermetallic compound, ErCu. Our measurements show that the ambient CsCl structure (: -3) is stable up to the highest pressure of the present measurements. A second-order Birch–Murnaghan equation of state fit to the pressure, volume data yielded a bulk modulus of 67.6 GPa with the pressure derivative of bulk modulus fixed at 4.

  3. Influence of ligand structure on anticancer and antioxidant properties of rhenium cluster compounds

    Directory of Open Access Journals (Sweden)

    I. V. Leus

    2009-11-01

    Full Text Available Under the model growth of T8 Guerin’s carcinoma in rats we studied the anticancer activity of the system rhenium-platinum, which includes cis-dicarboxylates of rhenium (III with different alkyl ligands, erythrocytes number and its morphological structure, erythrocytic stability, blood haemoglobin concentration, catalase activity and concentration of TBA-active products in the rats blood plasma. The renium-platinum system had considerable antioxidat effect and prevented the growth of tumour, that was maximal for a compound with the pivalate ligand.

  4. SYNTHESIS AND CRYSTAL STRUCTURE OF A NEW COMPOUND Sr6Sn2Nb8O30

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    A new compound Sr6Sn2Nb8O30 was found in th e ternary system of SrO-SnO2-Nb2O5.The transparent colorless crystal wit h n eedle-like shape can be grown by flux method.The crystal structure of new compo un d was determined by X-ray diffraction, and its belongs to tungsten bronze struc ture.Sr6Sn2Nb8O30 crystallizes in orthorhombic system with unit cell parameters a=17.579(1),b=17.509(1),c=7.7880(5),Z=4 and space group Cmm2.

  5. X-RAY CRYSTAL-STRUCTURE DETERMINATION OF THE TRICLINIC MISFIT LAYER COMPOUND (SNS)1.20TIS2

    NARCIS (Netherlands)

    WIEGERS, GA; MEETSMA, A; DEBOER, JL; VANSMAALEN, S; HAANGE, RJ

    1991-01-01

    (SnS)1.20TiS2 is a misfit layer compound built of alternately double layers of SnS with distorted rocksalt-type structure and sandwiches of TiS2 slightly distorted compared with those of 1T-TiS2. For comparison with other misfit layer compounds the triclinic subsystems are described in centred unit

  6. A quantitative structure-activity relationship for the acute toxicity of some epoxy compounds to the guppy

    NARCIS (Netherlands)

    Deneer, J.W.; Sinnige, T.L.; Seinen, W.; Hermens, J.L.M.

    1988-01-01

    The 14 day LC50 values of various epoxy compounds to the guppy (Poecilia reticulata) were determined, and investigated through the construction of a quantitative structure-activity relationship (QSAR). Both hydrophobicity and alkylating potency of the compounds are found to be necessary parameters f

  7. Determination of biodegradability kinetics of RCRA compounds using respirometry for structure-activity relationships

    Energy Technology Data Exchange (ETDEWEB)

    Tabak, H.H.; Desai, S.; Govind, R.

    1990-01-01

    Electrolytic respirometry is attaining prominence in biodegradation studies and is becoming one of the more suitable experimental methods for measuring the biodegradability and the kinetics of biodegradation of toxic organic compounds by the sewage, sludge, and soil microbiota and for determining substrate inhibitory effects to microorganisms in wastewater treatment systems. The purpose of the study was to obtain information on biological treatability of the benzene, phenol, phthalate, ketone organics and of the Superfund CERCLA organics bearing wastes in wastewater treatment systems which will support the development of an EPA technical guidance document on the discharge of the above organics to POTWs. The paper discusses the experimental design and procedural steps for the respirometric biodegradation and toxicity testing approach for individual organics or specific industrial wastes at different concentration levels in a mineral salts medium. A developed multi-level protocol is presented for determination of the biodegradability, microbial acclimation to toxic substrates and first order kinetic parameters of biodegradation for estimation of the Monod kinetic parameter of toxic organic compounds, in order to correlate the extent and rate of biodegradation with a predictive model based on chemical properties and molecular structure of these compounds. Respirometric biodegradation/inhibition and biokinetic data are provided for representative RCRA alkyl benzene and ketone organics.

  8. Biofiltration kinetics for volatile organic compounds (VOCs) and development of a structure-biodegradability relationship

    Energy Technology Data Exchange (ETDEWEB)

    Govind, R.; Wang, Z. [Univ. of Cincinnati, OH (United States). Dept. of Chemical Engineering; Bishop, D.F. [Environmental Protection Agency, Cincinnati, OH (United States). National Risk Management Research Lab.

    1997-12-31

    In recent years, regulation of hazardous air pollutants under the Clean Air Act and its amendments, has emerged as a major environmental issue. Major sources of volatile organic compounds (VOCs) in air are chemical production plants, manufacturing sites using common solvents, combustion sources, and waste treatment operations, such as waste water treatment plants, vacuum extraction of contaminated soils, and ground water stripping operations. Biofiltration is an emerging technology for treatment of biodegradable volatile organic compounds (VOCs) present in air. In biofiltration, the contaminants are contacted with active microorganisms present either in naturally bioactive materials, such as soil, peat, compost, etc., or immobilized on an inactive support media. Design of biofilters requires information on biodegradation kinetics which controls biofilter size. In this paper, an experimental microbiofilter system is presented which can be used to measure biofiltration kinetics for any volatile organic compound. A mathematical model is used to derive the Monod biokinetic parameters from the experimental data. Finally, a structure-bioactivity relationship is derived for estimating the biofiltration biokinetic parameters for a variety of VOCs.

  9. Three coordination compounds based on benzene tetracarboxylate ligand: syntheses, structures, thermal behaviors and luminescence properties

    Indian Academy of Sciences (India)

    YUNLONG WU; CHANGKUN XIA; JUN QIAN; JIMIN XIE

    2017-08-01

    Using 1,2,3,5-benzenetetracarboxylic acid and different pyridyl ligands, three metalorganic coordination compounds, [Co(H ₃btec)(1,10-phen)(H ₂O) ₃][OH]·2H ₂O (1), [Co ₂ (btec)(2,2’-bipy) ₂-(H ₂O)]·H ₂O (2), {[Co ₁.₅ (H ₂btec)(4,4’-bipy)(H ₂O) ₂][Co ₀.₅ (4,4’-bipy)- (H ₂O) ₄][OH] ₂} · 2H ₂O (3), (H ₄btec = 1, 2, 3, 5-benzenetetracarboxylic acid, 1,10-phen = 1,10-phenanthroline, 2,2’-bipy = 2,2_-bipyridine, 4,4’-bipy= 4,4_ -bipyridine) were synthesized by hydrothermal method and characterized by elemental analysis, infrared spectroscopy, and single-crystal X-ray diffraction analysis. X-ray crystallographic studies reveal that 1 is a discrete 0D coordination compound, while 2 and 3 possess similar 2D network structures, which show a sql network with the point symbol of (4,4). Thermal analysis indicates that compounds 1 and 2 begin to collapse after 350◦C. Further, the UV-Vis DRS spectra and solid-state luminescent properties of 1–3 have also been studied.

  10. Electronic band structures of AV(2) (A = Ta, Ti, Hf and Nb) Laves phase compounds.

    Science.gov (United States)

    Charifi, Z; Reshak, Ali Hussain; Baaziz, H

    2009-01-14

    First-principles density functional calculations, using the all-electron full potential linearized augmented plane wave method, have been performed in order to investigate the structural and electronic properties for Laves phase AV(2) (A = Ta, Ti, Hf and Nb) compounds. The generalized gradient approximation and the Engel-Vosko-generalized gradient approximation were used. Our calculations show that these compounds are metallic with more bands cutting the Fermi energy (E(F)) as we move from Nb to Ta, Hf and Ti, consistent with the increase in the values of the density of states at the Fermi level N(E(F)). N(E(F)) is controlled by the overlapping of V-p/d, A-d and A-p states around the Fermi energy. The ground state properties of these compounds, such as equilibrium lattice constant, are calculated and compared with the available literature. There is a strong/weak hybridization between the states, V-s states are strongly hybridized with A-s states below and above E(F). Around the Fermi energy we notice that V-p shows strong hybridization with A-p states.

  11. Magnetic structures of R(Cu, Ni)2 compounds (R = heavy rare earth) studied by neutron diffraction

    Science.gov (United States)

    Smetana, Z.; Šíma, V.

    1985-11-01

    Magnetics structures of powdered orthorhombic R(Cu, Ni)2 compounds (R = heavy rare earth) determined by neutron diffraction are described. The influence of magnetocrystalline anisotropy and exchange interactions on the type of magnetic ordering is discussed.

  12. Crystal Structure and X-ray Powder Diffraction Data for Rare Earth Compound PrNiSn

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The compound PrNiSn was studied by X-ray powder diffraction technique. The crystal structure and the X-ray diffraction data for this compound at room temperature were reported. The compound PrNiSn is orthorhombic with lattice parameters a=0.74569(3) nm, b=0.76851(5) nm, c=0.45676(8) nm, V=0.26176 nm3, Z=4 and Dx=8.076 g·cm-3, space group Pna21(33). The figure of merit FN for the compound is F30=54 (0.0093, 60).

  13. Peculiarities of Crystal Structure of the Cubic System Compounds with T 4 and T 5 Space Groups

    Science.gov (United States)

    Zolotarev, M. L.; Poplavnoi, A. S.

    2016-09-01

    We study symmetry peculiarities of crystalline compounds of a cubic system with the space groups T 4 and T 5 caused by the absence of point Wyckoff-sets in the unit cells of these groups. Due to the high multiplicity of the available Wyckoff positions, such compounds possess unit cells of complex composition. In these compounds, pseudosymmetry is realized with high probability when some group of atoms is located in positions close to the positions of higher-symmetry groups. We provide examples of crystalline compounds showing predicted specific structural features.

  14. Structure transition of multiferroic hexagonal TmMnO3 compound under high pressure

    Science.gov (United States)

    Wang, L. J.; Feng, S. M.; Zhu, J. L.; Liu, Q. Q.; Li, Y. C.; Li, X. D.; Liu, J.; Jin, C. Q.

    2010-06-01

    The high-pressure-induced structure transition in multiferroic hexagonal TmMnO3 (h-TmMnO3) has been investigated using an in situ angle-dispersive synchrotron X-ray diffraction technique in a diamond anvil cell. The experimental results show that the phase transition from ambient hexagonal to orthorhombic structure with space group Pbnm begins around 10.2 GPa. The Rietveld refinement method was used to determine the lattice parameters and lattice compressibility of the h-TmMnO3 compound from 0.8 to 28.6 GPa. The pressure evolution of average bond distances and bond angles between the Mn and O atoms in the ab-plane was obtained. The magnetic properties under different pressures as well as their effect on multiferroic properties are discussed using extrapolations from the empirical relation of magnetic order versus rare-earth ionic radius.

  15. Momentum-resolved electronic structure of the superconductor parent compound BaBiO3

    Science.gov (United States)

    Plumb, N. C.; Ristic, Z.; Park, J.; Wang, Z.; Matt, C. E.; Xu, N.; Lv, B. Q.; Gawryluk, D.; Pomjakushina, E.; Conder, K.; Wang, Y.; Johnston, S.; Mesot, J.; Shi, M.; Radovic, M.

    We use in situ angle-resolved photoemission to study thin films of BaBiO3, a parent compound of bismuthate superconductors with Tc up to 30 K. By simple electron counting, BaBiO3 should be metallic. However, in analogy with many unconventional and high-Tc superconductor families, it is instead insulating, and superconductivity emerges with doping. Our experiments reveal a folded band structure consistent with known BiO6 breathing distortions. However, charge ordering often thought to accompany the distortions is virtually nonexistent. The data combined with DFT calculations indicate that states near EF are primarily oxygen-derived. Hence BaBiO3 appears to be characterized by negative charge transfer energy. This can account for the seeming discrepancy between the atomic structure and ''missing'' charge order. It should also be relevant for understanding the doping evolution and superconductivity in bismuthates.

  16. Surface structure and energy of B2 type intermetallic compound NiAl

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jianmin [College of Physics and Information Technology, Shaanxi Normal University, Xian 710062, Shaanxi (China)], E-mail: jianm_zhang@yahoo.com; Wang Doudou [College of Physics and Information Technology, Shaanxi Normal University, Xian 710062, Shaanxi (China); Institute of Telecommunication Engineering of the Air Force Engineering University (AFEU1), Xian 710077, Shaanxi (China); Chen Guoxiang [School of Science, Xian Shiyou University, Xian 710065, Shaanxi (China); Xu Kewei [State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xian 710049, Shaanxi (China)

    2008-02-15

    The surface structure and energies for 22 surfaces of NiAl, an ordered intermetallic compound of B2 structure, have been studied by using embedded atom method. The results show that, for alternating Ni and Al surfaces with odd numbers of the sum of their three Miller indices, the energy difference between the Ni terminated surface and Al terminated surface increase linearly with increasing the interlayer distance. So from surface energy minimization, the Al terminated surface is favorable for each alternating Ni and Al surface. This is in agreement with experimental results. However, the energy of the (1 1 0) surface belonged to the other kind of the surface consisted of stoichiometric atomic layers and with even numbers of the sum of their three Miller indices, is the lowest in all two kinds of the surfaces. Therefore the (1 1 0) texture of NiAl appears mostly in the experiments.

  17. Electronic structure of ionic PbFCl-type compounds under pressure

    CERN Document Server

    Kanchana, V; Rajagopalan, M

    2003-01-01

    The electronic structures of alkaline-earth fluoro-halides - SrFBr, SrFI, and CaFBr, which crystallize in the PbFCl-type structure - have been studied using the tight-binding linear muffin-tin orbital method within the local density approximation. The total energies were calculated using the atomic sphere approximation and were used to determine the ground state properties of these systems. The calculated ground state properties agree fairly well with the experimental results. These systems were found to be direct band gap insulators. The pressure dependence of the band gap was also studied. The band gap closes at high pressures leading to band overlap. A possible reason for the metallization in these compounds is discussed.

  18. STRUCTURE AND SUPERCONDUCTIVITY OF Mg(B1-xCx)2 COMPOUNDS

    Institute of Scientific and Technical Information of China (English)

    ZHANG SHAO-YING; CHENG ZHAO-HUA; SHEN BAO-GEN; RONG CHUAN-BING; ZHAO TONG-YUN; ZHANG JIAN

    2001-01-01

    In this paper, we report on the structural properties and superconductivity of Mg(B1-xCx)2 compounds. Powder X-ray diffraction results indicate that the samples crystallize in a hexagonal AlB2-type structure. Due to the chemical activity of Mg powders, a small amount of MgO impurity phase is detected by X-ray diffraction. The lattice parameters decrease slightly with the increasing carbon content. Magnetization measurements indicate that the non-stoichiometry of MgB2 has no influence on the superconducting transition temperature and the transition temperature width. The addition of carbon results in a decrease of Tc and an increase of the superconducting transition width, implying the loss of superconductivity.

  19. A first principle study of band structure of III-nitride compounds

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Rashid [Centre for High Energy Physics University of the Punjab, Lahore-54590 (Pakistan)]. E-mail: rasofi@hotmail.com; Akbarzadeh, H. [Department of Physics, Isfahan University of Technology, 841546 Isfahan (Iran, Islamic Republic of); Fazal-e-Aleem [Centre for High Energy Physics University of the Punjab, Lahore-54590 (Pakistan)

    2005-12-15

    The band structure of both phases, zinc-blende and wurtzite, of aluminum nitride, indium nitride and gallium nitride has been studied using computational methods. The study has been done using first principle full-potential linearized augmented plane wave (FP-LAPW) method, within the framework of density functional theory (DFT). For the exchange correlation potential, generalized gradient approximation (GGA) and an alternative form of GGA proposed by Engel and Vosko (GGA-EV) have been used. Results obtained for band structure of these compounds have been compared with experimental results as well as other first principle computations. Our results show a significant improvement over other theoretical work and are closer to the experimental data.

  20. Structural characterization and physicochemical features of new hybrid compound containing chlorate anions of cadmate (II)

    Science.gov (United States)

    Lassoued, Mohamed Saber; Abdelbaky, Mohammed S. M.; Lassoued, Abdelmajid; Gadri, Abdellatif; Ammar, Salah; Ben Salah, Abdelhamid; García-Granda, Santiago

    2017-08-01

    The present paper reports the synthesis of a single crystal of a new organic-inorganic hybrid compound, with the formula (C6H14N2) CdCl4·H2O, by slow evaporation method at room temperature. It was characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Hirshfeld surface, spectroscopy measurement, thermal study and photoluminescence (PL) properties. A preliminary SCXRD structural analysis revealed that it crystallized in the monoclinic system (space group P21/c) with the following unit cell parameters: a = 12.95823(16) Å, b = 14.92449(16) Å, c = 7.13838(9) Å and β = 103.2108(12)° with Z = 4. The refinement converged to R = 0.0164 and ωR = 0.0393. Its atomic arrangement can be described as an alternation of organic and inorganic layers along the a-axis. The crystal packing was governed by the N-H⋯Cl and O-H⋯Cl hydrogen bonding interaction between the 1.2-diammoniumcyclohexane cations, the [CdCl42n-]n anions and water molecule. The Hirshfeld surface analysis was conducted to investigate intermolecular interactions and associated 2D fingerprint plots, revealing the relative contribution of these interactions in the crystal structure quantitatively. Furthermore, the room temperature infrared (IR) spectrum of the title compound was recorded and analyzed on the basis of data found in the literature. Besides, the thermal analysis studies were performed, but no phase transition was found in the temperature range between 30 and 450 °C. The optical and PL properties of the compound were investigated in the solid state at room temperature and exhibited three bands at 225, 268 and 315 nm and a strong fluorescence at 443 nm.

  1. Structure-Function Elucidation of Antioxidative and Prooxidative Activities of the Polyphenolic Compound Curcumin

    Directory of Open Access Journals (Sweden)

    Parth Malik

    2014-01-01

    Full Text Available Phenolic compounds have been very well known for their antioxidant properties, owing to their unique ability to act as free radical scavengers which, in turn, is an outstanding attribute of their unique biochemical structure. Recent accumulating lines of evidence inculcate sustainable interest and curiosity towards the chemoprotective nature of the natural polyphenolic compound curcumin (diferuloylmethane against oxidative stress-mediated disorders. Curcumin is naturally found as a constituent of dietary spices called turmeric, extracted from the plant Curcuma longa. However, like every phenolic antioxidant, curcumin possesses a concentration and medium dependent anti- and pro-oxidant behaviour. A detailed study of the structure-function analysis and the understanding of the mode of action of curcumin as well as its chemical analogues is thus essential to understand the selective biochemical consequences of curcumin. Moreover, the presence of transition metal ions, route of administration, and localized tissue are also the vital decisive factors to determine curcumin behaviour. With this viewpoint, this paper sheds lights on the medium dependent prooxidative and antioxidative attributes of curcumin. Further, with respect to emergence of nanocarriers, a brief discussion focusing on the biochemical effect exertion of curcumin chiefly due to targeted and slow release has also been added towards the end.

  2. The structural diversity of ABS₃ compounds with d⁰ electronic configuration for the B-cation.

    Science.gov (United States)

    Brehm, John A; Bennett, Joseph W; Schoenberg, Michael Rutenberg; Grinberg, Ilya; Rappe, Andrew M

    2014-06-14

    We use first-principles density functional theory within the local density approximation to ascertain the ground state structure of real and theoretical compounds with the formula ABS3 (A = K, Rb, Cs, Ca, Sr, Ba, Tl, Sn, Pb, and Bi; and B = Sc, Y, Ti, Zr, V, and Nb) under the constraint that B must have a d(0) electronic configuration. Our findings indicate that none of these AB combinations prefer a perovskite ground state with corner-sharing BS6 octahedra, but that they prefer phases with either edge- or face-sharing motifs. Further, a simple two-dimensional structure field map created from A and B ionic radii provides a neat demarcation between combinations preferring face-sharing versus edge-sharing phases for most of these combinations. We then show that by modifying the common Goldschmidt tolerance factor with a multiplicative term based on the electronegativity difference between A and S, the demarcation between predicted edge-sharing and face-sharing ground state phases is enhanced. We also demonstrate that, by calculating the free energy contribution of phonons, some of these compounds may assume multiple phases as synthesis temperatures are altered, or as ambient temperatures rise or fall.

  3. Structural Elucidation of two Compounds from the Fruit of Medicinally Important Plant, Basella Rubra

    Directory of Open Access Journals (Sweden)

    Swarnali Nath Choudhury

    2016-03-01

    Full Text Available Basella rubra is a medicinal plant species found in India and other parts of Asia and tropical Africa. It improves the appetite, useful in biliousness, leprosy, dysentery, ulcers and it has antiviral and antipyretic activity. The red pigment from the fruit has good colouring ability. It is bright purple at pH 3-7. It is a good additive and a safe, non-poisonous colorant. At present, the dyestuff industry has grown rapidly because of the vital role played by small – scale sector, which is responsible for the production of azo, acids, basics and direct dyes. But such synthetic dyes have toxic effect and hence may not be useful in edible substances. Therefore keeping this in mind the structure of two separated compounds from the fruit pigment of medicinally important plant Besella rubra were elucidated. The structures of the compounds have been characterized on the basis of spectral data such as IR, 1H NMR, 13C NMR and Mass spectral studies.

  4. Electronic structure and magnetism in doped semiconducting half-Heusler compounds

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, B R K; Dasgupta, I [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2005-08-24

    We have studied in detail the electronic structure and magnetism in M (Mn and Cr)-doped semiconducting half-Heusler compounds FeVSb, CoTiSb and NiTiSn (XY{sub x}M{sub 1-x}Z) in a wide concentration range using the local-spin density functional method in the framework of the tight-binding linearized muffin tin orbital method (TB-LMTO) and supercell approach. Our calculations indicate that some of these compounds are not only ferromagnetic but also half-metallic and may be useful for spintronics applications. The electronic structure of the doped systems is analysed with the aid of a simple model where we have considered the interaction between the dopant transition metal (M) and the valence band X-Z hybrid. We have shown that the strong X-d-M-d interaction places the M-d states close to the Fermi level with the M-t{sub 2g} states lying higher in energy in comparison to the M-e{sub g} states. Depending on the number of available d electrons, ferromagnetism is realized provided that the d manifold is partially occupied. The tendencies toward ferromagnetic (FM) or antiferromagnetic (AFM) behaviour are discussed within Anderson-Hasegawa models of super-exchange and double-exchange. In our calculations for Mn-doped NiTiSn, the strong preference for FM over AFM ordering suggests a possible high Curie temperature for these systems.

  5. Structural and sensory characterization of key pungent and tingling compounds from black pepper (Piper nigrum L.).

    Science.gov (United States)

    Dawid, Corinna; Henze, Andrea; Frank, Oliver; Glabasnia, Anneke; Rupp, Mathias; Büning, Kirsten; Orlikowski, Diana; Bader, Matthias; Hofmann, Thomas

    2012-03-21

    To gain a more comprehensive knowledge on whether, besides the well-known piperine, other compounds are responsible for the pungent and tingling oral impression imparted by black pepper, an ethanol extract prepared from black pepper (Piper nigrum L.) was screened for its key sensory-active nonvolatiles by application of taste dilution analysis (TDA). Purification of the compounds perceived with the highest sensory impact, followed by LC-MS and 1D/2D NMR experiments as well as synthesis, led to the structure determination of 25 key pungent and tingling phytochemicals, among which the eight amides 1-(octadeca-2E,4E,13Z-trienyl)piperidine, 1-(octadeca-2E,4E,13Z-trienyl)pyrrolidine, (2E,4E,13Z)-N-isobutyl-octadeca-2,4,13-trienamide, 1-(octadeca-2E,4E,12Z-trienoyl)-pyrrolidine, 1-(eicosa-2E,4E,15Z-trienyl)piperidine, 1-(eicosa-2E,4E,15Z-trienyl)pyrrolidine, (2E,4E,15Z)-N-isobutyl-eicosa-2,4,15-trienamide, and 1-(eicosa-2E,4E,14Z-trienoyl)-pyrrolidine were not yet reported in literature. Sensory studies by means of a modified half-tongue test revealed recognition thresholds ranging from 3.0 to 1150.2 nmol/cm² for pungency and from 520.6 to 2162.1 nmol/cm² for the tingling orosensation depending on their chemical structure.

  6. Structure-Activity Relationship Analysis of the Thermal Stabilities of Nitroaromatic Compounds Following Different Decomposition Mechanisms.

    Science.gov (United States)

    Li, Jiazhong; Liu, Huanxiang; Huo, Xing; Gramatica, Paola

    2013-02-01

    The decomposition behavior of energetic materials is very important for the safety problems concerning their production, transportation, use and storage, because molecular decomposition is intimately connected to their explosive properties. Nitroaromatic compounds, particularly nitrobenzene derivatives, are often considered as prototypical energetic molecules, and some of them are commonly used as high explosives. Quantitative structure-activity relationship (QSAR) represents a potential tool for predicting the thermal stability properties of energetic materials. But it is reported that constructing general reliable models to predict their stability and their potential explosive properties is a very difficult task. In this work, we make our efforts to investigate the relationship between the molecular structures and corresponding thermal stabilities of 77 nitrobenzene derivatives with various substituent functional groups (in ortho, meta and/or para positions). The proposed best MLR model, developed by the new software QSARINS, based on Genetic Algorithm for variable selection and with various validation tools, is robust, stable and predictive with R(2) of 0.86, QLOO (2) of 0.79 and CCC of 0.90. The results indicated that, though difficult, it is possible to build predictive, externally validated QSAR models to estimate the thermal stability of nitroaromatic compounds. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. On the structure and normal modes of hydrogenated Ti-fullerene compounds

    Energy Technology Data Exchange (ETDEWEB)

    Tlahuice-Flores, Alfredo, E-mail: tlahuicef@yahoo.com [Universidad Nacional Autonoma de Mexico, Instituto de Fisica (Mexico); Mejia-Rosales, Sergio, E-mail: sergio.mejiars@uanl.edu.mx [Universidad Autonoma de Nuevo Leon, CICFIM-Facultad de Ciencias Fisico Matematicas, and Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia (Mexico); Galvan, Donald H., E-mail: donald@cnyn.unam.mx [Centro de Nanociencias y Nanotecnologia-Universidad Nacional Autonoma de Mexico (Mexico)

    2012-08-15

    When titanium covers a C{sub 60} core, the metal atoms may suppress the fullerene's capacity of storing hydrogen, depending on the number of Ti atoms covering the C{sub 60} framework, the Ti-C binding energy, and diffusion barriers. In this article, we study the structural and vibrational properties of the C{sub 60}TiH{sub n} (n = 2, 4, 6, and 8) and C{sub 60}Ti{sub 6}H{sub 48} compounds. The IR spectra of C{sub 60}TiH{sub n} compounds have a maximum attributable to the Ti-H stretching mode, which shifts to lower values in the structures with n = 4, 8, while their Raman spectra show two peaks corresponding to the stretching modes of H{sub 2} molecules at apical and azimuthal positions. On the other hand, the IR spectrum of C{sub 60}Ti{sub 6}H{sub 48} shows an intense peak due to the Ti-H in-phase stretching mode, while its Raman spectrum has a maximum attributed to the pentagonal pinch of the C{sub 60} core. Finally, we have found that the presence of one apical H{sub 2} molecule enhances the pentagonal pinch mode, becoming the maximum in the Raman spectrum.Graphical Abstract.

  8. Compound semiconductor alloys: From atomic-scale structure to bandgap bowing

    Energy Technology Data Exchange (ETDEWEB)

    Schnohr, C. S., E-mail: c.schnohr@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2015-09-15

    Compound semiconductor alloys such as In{sub x}Ga{sub 1−x}As, GaAs{sub x}P{sub 1−x}, or CuIn{sub x}Ga{sub 1−x}Se{sub 2} are increasingly employed in numerous electronic, optoelectronic, and photonic devices due to the possibility of tuning their properties over a wide parameter range simply by adjusting the alloy composition. Interestingly, the material properties are also determined by the atomic-scale structure of the alloys on the subnanometer scale. These local atomic arrangements exhibit a striking deviation from the average crystallographic structure featuring different element-specific bond lengths, pronounced bond angle relaxation and severe atomic displacements. The latter, in particular, have a strong influence on the bandgap energy and give rise to a significant contribution to the experimentally observed bandgap bowing. This article therefore reviews experimental and theoretical studies of the atomic-scale structure of III-V and II-VI zincblende alloys and I-III-VI{sub 2} chalcopyrite alloys and explains the characteristic findings in terms of bond length and bond angle relaxation. Different approaches to describe and predict the bandgap bowing are presented and the correlation with local structural parameters is discussed in detail. The article further highlights both similarities and differences between the cubic zincblende alloys and the more complex chalcopyrite alloys and demonstrates that similar effects can also be expected for other tetrahedrally coordinated semiconductors of the adamantine structural family.

  9. First-principles calculations of structural properties of Sc{sub 1-x}In{sub x}N compound

    Energy Technology Data Exchange (ETDEWEB)

    Perez, William Lopez [Departamento de Matematicas y Fisica, Universidad del Norte, A. A. 1569, Barranquilla (Colombia)]. E-mail: wlopez@uninorte.edu.co; Arbey Rodriguez M, Jairo [Departamento de Fisica, Universidad Nacional de Colombia, A. A. 5997, Bogota (Colombia); Moreno-Armenta, Maria G. [Centro de Ciencias de la Materia Condensada, Universidad Nacional Autonoma de Mexico, A. P. 2681, Ensenada Baja California 22800 (Mexico)

    2007-09-01

    We have applied the full-potential linearized augmented plane wave method (FP-LAPW) within the density functional theory to investigate the structural properties of Sc{sub 1-x}In{sub x}N compound in sodium chloride and wurtzite structures. We have found that the lattice parameter (a) increases with the increment of the In-composition in both structures, while the bulk modulus diminishes with the increase of the In-composition. The lattice constant and the bulk modulus present a small bowing in both structures. We have also analyzed the relative stability of this ternary compound in the two studied phases. We have found that sodium chloride structure is the ground state phase for a In-composition range 0=structure is most stable in the range 0.5=compounds are in good agreement with the experimental data.

  10. Synthesis, structures of four coordination compounds constructed from o-methacrylamidobenzoic acid and their relationship between structure and solid state luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong-Xia; Ma, Yong; Zhou, Feng; Wu, Bing [Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry, Chemical Engineering and Materials Science, Soochow University(DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Key Laboratory of Energy-Saving And Environmental Protection Materials Test and Technical Service Center of Jiangsu Province, Soochow University (DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Xu, Qing-Feng, E-mail: xuqingfeng@suda.edu.cn [Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry, Chemical Engineering and Materials Science, Soochow University(DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Key Laboratory of Energy-Saving And Environmental Protection Materials Test and Technical Service Center of Jiangsu Province, Soochow University (DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Lu, Jian-Mei, E-mail: lujm@suda.edu.cn [Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry, Chemical Engineering and Materials Science, Soochow University(DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Key Laboratory of Energy-Saving And Environmental Protection Materials Test and Technical Service Center of Jiangsu Province, Soochow University (DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Ge, Jian-Feng [Key Laboratory of Organic Synthesis of Jiangsu Province, School of Chemistry, Chemical Engineering and Materials Science, Soochow University(DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China); Key Laboratory of Energy-Saving And Environmental Protection Materials Test and Technical Service Center of Jiangsu Province, Soochow University (DuShuHu Campus), 199 Renai Road, Suzhou, 215123 (China)

    2013-07-15

    Four new coordination compounds, namely, Zn(o-MAABA){sub 2}(Phen) (1), [Cd(o-MAABA){sub 2}·2H{sub 2}O]{sub 2} (2), ([Pb{sub 2}Cl{sub 2}(o-MAABA){sub 2}(Phen){sub 4}])·2H{sub 2}O (3·2H{sub 2}O), [Pb(NO{sub 3})(o-MAABA)(Phen)]{sub n} (4), where o-MAABA=o-methacrylamidobenzoic acid and phen=1, 10-phenanthroline, have been synthesized. All compounds were fully confirmed by FT-IR, elemental analysis and TGA analysis. Their structures were determined by single crystal X-ray diffraction, in which compound 1 shows a mononuclear structure, compounds 2 and 3 have binuclear structures and compound 4 shows an infinite chain. In 2 and 4, the adjacent chains are extended into a 3D supramolecular architecture via π–π interactions. Solid-state room temperature luminescence spectra revealed that emission bands of compound 1 were located at 524 nm (λ{sub ex}=352 nm) and compound 4 at 479 and 584 nm (λ{sub ex}=390 nm) assigned to the excimer formation. The emission at 454 nm (λ{sub ex}=340 nm) of compound 2 was mainly ascribed to the Ligand–Metal Charge Transfer (LMCT). - Graphical abstract: Four coordination compounds constructed by o-methacrylamidobenzoic, phenanthroline and metal ions are reported. The photoluminescent properties is studied, which is affected by the molecular stacking and LMCT.

  11. Initial atmospheric corrosion of Zinc sprayed with NaCl

    Institute of Scientific and Technical Information of China (English)

    屈庆; 严川伟; 张蕾; 刘光恒; 曹楚南

    2003-01-01

    Regularities of the initial atmospheric corrosion of zinc sprayed with different amount of NaCl exposed to air at 80% relative humidity and 25 ℃ were investigated via quartz crystal microbalance in laboratory. The results show that NaCl can accelerate the corrosion of zinc. Mass gain of zinc increases with the exposure time increasing, which can be correlated by using exponential decay function. The relationship between mass gain and amount of NaCl sprayed at a certain exposure time follows a quadratic function. Meanwhile, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and electron dispersion X-ray analysis were used to characterize the corrosion surface and products. Zn5(OH)8Cl2*H2O and ZnO are the dominant corrosion products, which unevenly distribute on the surface of zinc in the presence of NaCl. A probable mechanism is simply presented to explain the experimental results.

  12. QSAR study on estrogenic activity of structurally diverse compounds using generalized regression neural network

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Computer-based quantitative structure-activity relationship (QSAR) model has been becoming a pow- erful tool in understanding the structural requirements for chemicals to bind the estrogen receptor (ER), designing drugs for human estrogen replacement therapy, and identifying potential estrogenic endo- crine disruptors. In this study, a simple yet powerful neural network technique, generalized regression neural network (GRNN) was used to develop a QSAR model based on 131 structurally diverse estro- gens (training set). Only nine descriptors calculated solely from the molecular structures of com- pounds selected by objective and subjective feature selections were used as inputs of the GRNN model. The predictive power of the built model was found to be comparable to that of the more traditional techniques but requiring significantly easy implementation and a shorter computation-time. The ob- tained result indicates that the proposed GRNN model is robust and satisfactory, and can provide a feasible and practical tool for the rapid screening of the estrogenic activity of organic compounds.

  13. Morphological and structural characterization of Sm–O–S compounds prepared by thermolysis of dithiocarbamate precursors

    Energy Technology Data Exchange (ETDEWEB)

    Signore, M.A. [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy); Taurino, A., E-mail: antonietta.taurino@cnr.it [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy); Catalano, M. [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy); Bellini, E., E-mail: Eleonora.Bellini@le.infn.it [Mathematical and Physics Department “E. De Giorgi”, University of Salento, via Arnesano, 73100 Lecce (Italy); Di Girolamo, G., E-mail: giovanni.digirolamo@enea.it [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy); Laera, A.M., E-mail: anna.laera@unisalento.it [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy); Quaranta, F. [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy); Vasanelli, L. [Dipartimento Ingegneria Innovazione, University of Lecce, Lecce (Italy); Siciliano, P. [Italian National Research Council, Institute for Microelectronics and Microsystems, Lecce (Italy)

    2014-04-01

    Deposition and structural characterization of Sm{sub x}S{sub y}O{sub z}-based thin films are reported. The chemical synthesis of the Sm{sub x}S{sub y}O{sub z} compounds is performed by thermolysis of dithiocarbamate precursors, followed by the drop casting deposition of the synthesized material, and by the thermal treatment at different temperatures (250 °C, 500 °C and 900 °C) and atmospheric conditions (nitrogen and air). Structural and morphological properties have been investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction, and were found to depend closely on the treatment conditions. In particular, the treatment at temperatures as high as 900 °C and in a nitrogen atmosphere enhances the crystalline nature of the films and increases the samarium content in comparison to the oxygen content. Therefore, the temperature of 900 °C and the nitrogen atmosphere represent the optimal treatment conditions, among the process parameters, to obtain a single phase of Sm{sub 2}SO{sub 2}. - Highlights: • Sm–O–S compounds have been synthesized by a simple and low cost chemical route. • The films were treated at different temperatures and different atmospheres. • The film structure and chemical composition were studied. • SmxOySz physical properties were tuned with temperature and atmosphere treatment. • At 900 °C in nitrogen atmosphere a single phase of Sm2O2S is obtained.

  14. Structural and Optoelectronic Properties of X3ZN (X = Ca, Sr, Ba; Z = As, Sb, Bi) Anti-Perovskite Compounds

    Science.gov (United States)

    Ullah, Imran; Murtaza, G.; Khenata, R.; Mahmood, Asif; Muzzamil, M.; Amin, N.; Saleh, M.

    2016-06-01

    We employed first-principles calculations to predict the structural and optoelectronic properties of X3ZN (X = Ca, Sr, Ba; Z = As, Sb, Bi) anti-perovskite compounds using an all-electron full-potential linearized augmented plane-wave method. Optimized structural parameters are found to be in good agreement with the available experimental measurements. The electronic band structure is calculated using different exchange-correlation potentials which reveal that the investigated compounds are narrow direct band gap semiconductors. A direct narrow band gap at the center of the Brillouin zone emphasises the optical activity of these compounds. Prediction of the optical properties, such as the real and imaginary parts of the dielectric function and refractive index along with reflectivity and optical conductivity, reveals the importance of these compounds in the visible and near UV optoelectronic devices industry.

  15. Study of structural, electronic and elastic properties of RPd{sub 3} (R = Lu and Sc) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Veena, E-mail: gita-pagare@yahoo.co.in; Pagare, Gitanjali, E-mail: gita-pagare@yahoo.co.in; Chouhan, S. S., E-mail: gita-pagare@yahoo.co.in [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal-462002 (India); Sanyal, S. P. [Department of Physics, Barkatullah University, Bhopal-462026 (India)

    2014-04-24

    The structural, electronic and elastic properties of nonmagnetic RPd{sub 3} (R = Lu and Sc) compounds, which crystallize in AuCu{sub 3}-type structure, are studied using first principles density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The calculations are carried out within the PBE-GGA and WC-GGA for the exchange correlation potential. Our calculated ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B’) are in good agreement with the experimental results. We first time predict the elastic constants for these compounds using different approximations of GGA. These RPd{sup 3} compounds are found to be ductile in nature in accordance with Pugh’s criteria. The computed electronic band structures and density of states show metallic character of these compounds.

  16. The effect of yeast extract addition on quality of fermented sausages at low NaCl content.

    Science.gov (United States)

    Campagnol, Paulo Cezar Bastianello; dos Santos, Bibiana Alves; Wagner, Roger; Terra, Nelcindo Nascimento; Pollonio, Marise Aparecida Rodrigues

    2011-03-01

    Fermented sausages with 25% or 50% of their NaCl replaced by KCl and supplemented with 1% or 2% concentrations of yeast extract were produced. The sausage production process was monitored with physical, chemical and microbiological analyses. After production, the sausage samples were submitted to a consumer study and their volatile compounds were extracted by solid-phase microextraction and analyzed by GC-MS. The replacement of NaCl by KCl did not significantly influence the physical, chemical or microbiological characteristics. The sensory quality of the fermented sausages with a 50% replacement was poor compared with the full-salt control samples. The use of yeast extract at a 2% concentration increased volatile compounds that arose from amino acids and carbohydrate catabolism. These compounds contributed to the suppression of the sensory-quality defects caused by the KCl introduction, thus enabling the production of safe fermented sausages that have acceptable sensory qualities with half as much sodium content.

  17. Structural and property studies on metal–organic compounds with 3-D supramolecular network

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qi-Ying; Ma, Ke-Fang; Xiao, Hong-Ping; Li, Xin-Hua; Shi, Qian, E-mail: shiq@wzu.edu.cn

    2014-07-01

    Two carboxylato-bridged allomeric compounds, ([Cu{sub 2}(dbsa){sub 2}(hmt) (H{sub 2}O){sub 4}]{sub 1/2}·2H{sub 2}O){sub n} (1), ([Ni(dbsa)(H{sub 2}O){sub 2}]{sub 1/2}[Ni(dbsa)(hmt)(H{sub 2}O){sub 2}]{sub 1/2}·2H{sub 2}O){sub n} (2) (H{sub 2}dbsa=meso-2,3-dibromosuccinic acid, hmt=hexamethylenetetramine) have been synthesized and characterized by X-ray structral analyses. The metal ions have two kinds of coordination fashion in one unit, and bridged by carboxylate and hmt ligands along with weak interactions existing in the solid structure, forming a 3-D supramolecular network. Variable-temperature magnetic property studies reveal the existence of antiferromagnetic interactions in 1 and 2 with g=2.2, J{sub 1}=−3.5 cm{sup −1}, J{sub 2}=−2.8 cm{sup −1} for 1, and g=2.1, J=−3.5 cm{sup −1} for 2. - Graphical abstract: Variable-temperature magnetic property studies of two 3-D supramolecular compounds reveal the existence of antiferromagnetic interactions between the metal ions, through the effective super-exchange media. - Highlights: • Two 3-D allomeric Cu(II) and Ni(II) metal–organic compounds have been prepared. • The 3-D networks were constructed by coordination bonds, weak interactions and hydrogen bond interactions. • There are antiferromagnetic super-exchange interactions between the metal ions.

  18. The effect of fatty acid surfactants on the uptake of nitric acid to deliquesced NaCl aerosol

    Directory of Open Access Journals (Sweden)

    M. Ammann

    2008-09-01

    Full Text Available Surface active organic compounds have been observed in marine boundary layer aerosol. Here, we investigate the effect such surfactants have on the uptake of nitric acid (HNO3, an important removal reaction of nitrogen oxides in the marine boundary layer. The uptake of gaseous HNO3 on deliquesced NaCl aerosol was measured in a flow reactor using HNO3 labelled with the short-lived radioactive isotope 13N. The uptake coefficient γ on pure deliquesced NaCl aerosol was γ=0.5±0.2 at 60% relative humidity and 30 ppb HNO3(g. The uptake coefficient was reduced by a factor of 5–50 when the aerosol was coated with saturated linear fatty acids with carbon chain lengths of 18 and 15 atoms in monolayer quantities. In contrast, neither shorter saturated linear fatty acids with 12 and 9 carbon atoms, nor coatings with the unsaturated oleic acid (C18, cis-double bond had a detectable effect on the rate of HNO3 uptake. It is concluded that it is the structure of the monolayers formed, which determines their resistance towards HNO3 uptake. Fatty acids (C18 and C15, which form a highly ordered film in the so-called liquid condensed state, represent a significant barrier towards HNO3 uptake, while monolayers of shorter-chain fatty acids (C9, C12 and of the unsaturated oleic acid form a less ordered film in the liquid expanded state and do not hinder the uptake. Similarly, high contents of humic acids in the aerosol, a structurally inhomogeneous, quite water soluble mixture of oxidised high molecular weight organic compounds did not affect HNO3 uptake. As surfactant films on naturally occurring aerosol are expected to be less structured due to their chemical inhomogeneity, it is likely that their inhibitory effect on HNO3 uptake is smaller than that observed here for the C15 and C18 fatty acid monolayers.

  19. Accurate thermoelastic tensor and acoustic velocities of NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Marcondes, Michel L., E-mail: michel@if.usp.br [Physics Institute, University of Sao Paulo, Sao Paulo, 05508-090 (Brazil); Chemical Engineering and Material Science, University of Minnesota, Minneapolis, 55455 (United States); Shukla, Gaurav, E-mail: shukla@physics.umn.edu [School of Physics and Astronomy, University of Minnesota, Minneapolis, 55455 (United States); Minnesota supercomputer Institute, University of Minnesota, Minneapolis, 55455 (United States); Silveira, Pedro da [Chemical Engineering and Material Science, University of Minnesota, Minneapolis, 55455 (United States); Wentzcovitch, Renata M., E-mail: wentz002@umn.edu [Chemical Engineering and Material Science, University of Minnesota, Minneapolis, 55455 (United States); Minnesota supercomputer Institute, University of Minnesota, Minneapolis, 55455 (United States)

    2015-12-15

    Despite the importance of thermoelastic properties of minerals in geology and geophysics, their measurement at high pressures and temperatures are still challenging. Thus, ab initio calculations are an essential tool for predicting these properties at extreme conditions. Owing to the approximate description of the exchange-correlation energy, approximations used in calculations of vibrational effects, and numerical/methodological approximations, these methods produce systematic deviations. Hybrid schemes combining experimental data and theoretical results have emerged as a way to reconcile available information and offer more reliable predictions at experimentally inaccessible thermodynamics conditions. Here we introduce a method to improve the calculated thermoelastic tensor by using highly accurate thermal equation of state (EoS). The corrective scheme is general, applicable to crystalline solids with any symmetry, and can produce accurate results at conditions where experimental data may not exist. We apply it to rock-salt-type NaCl, a material whose structural properties have been challenging to describe accurately by standard ab initio methods and whose acoustic/seismic properties are important for the gas and oil industry.

  20. Pressure induced structural phase transition in IB transition metal nitrides compounds

    Energy Technology Data Exchange (ETDEWEB)

    Soni, Shubhangi; Kaurav, Netram, E-mail: netramkaurav@yahoo.co.uk; Jain, A. [Department of Physics, Govt. Holkar Science college, A. B. Road, Indore-452001 India (India); Shah, S. [Department of Physics, P. M. B. Gujarati Science College, Indore-452001 (India); Choudhary, K. K. [Department of Physics, National Defence Academy, Khadakwasla, Pune-411 0231 India (India)

    2015-06-24

    Transition metal mononitrides are known as refractory compounds, and they have, relatively, high hardness, brittleness, melting point, and superconducting transition temperature, and they also have interesting optical, electronic, catalytic, and magnetic properties. Evolution of structural properties would be an important step towards realizing the potential technological scenario of this material of class. In the present study, an effective interionic interaction potential (EIOP) is developed to investigate the pressure induced phase transitions in IB transition metal nitrides TMN [TM = Cu, Ag, and Au] compounds. The long range Coulomb, van der Waals (vdW) interaction and the short-range repulsive interaction upto second-neighbor ions within the Hafemeister and Flygare approach with modified ionic charge are properly incorporated in the EIOP. The vdW coefficients are computed following the Slater-Kirkwood variational method, as both the ions are polarizable. The estimated value of the phase transition pressure (Pt) and the magnitude of the discontinuity in volume at the transition pressure are consistent as compared to the reported data.

  1. Structure-activity relationship study of novel anticancer aspirin-based compounds.

    Science.gov (United States)

    Joseph, Stancy; Nie, Ting; Huang, Liqun; Zhou, Hui; Atmakur, Krishnaiah; Gupta, Ramesh C; Johnson, Francis; Rigas, Basil

    2011-01-01

    We performed a structure-activity relationship (SAR) study of a novel aspirin (ASA) derivative, which shows strong anticancer activity in vitro and in vivo. A series of ASA-based benzyl esters (ABEs) were synthesized and their inhibitory activity against human colon (HT-29 and SW480) and pancreatic (BxPC-3 and MIA PaCa-2) cancer cell lines was evaluated. The ABEs that we studied largely comprise organic benzyl esters bearing an ASA or acyloxy group (X) at the meta or para position of the benzyl ring and one of four different leaving groups. The nature of the salicyloyl/acyloxy function, the leaving group, and the additional substituents affecting the electron density of the benzyl ring, all were influential determinants of the inhibitory activity on cancer cell growth for each ABE. Positional isomerism also played a significant role in this effect. The mechanism of action of these compounds appears consistent with the notion that they generate either a quinone methide or an m-oxybenzyl zwitterion (or an m-hydroxybenzyl cation), which then reacts with a nucleophile, mediating their biological effect. Our SAR study provides an insight into the biological properties of this novel class of compounds and underscores their potential as anticancer agents.

  2. 3D-quantitative structure-activity relationship study of organophosphate compounds

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jinsong; WANG Bin; DAI Zhaoxia; WANG Xiaodong; KONG Lingren; WANG Liansheng

    2004-01-01

    The biological effects of most organophosphate compounds (OP) are arising by inhibition of the enzyme acetylcholinesterase (AChE). The 3D-quantitative structure-activity relationship (3D-QSAR) on the acute toxicity to housefly (Musca nobulo L.) of 35 dialkyl phenyl phosphate compounds are studied by using comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) methods, and the reaction mechanism between the OP and the AChE are discussed. In contrast to classical QSAR methods, CoMFA and CoMSIA, especially the combination of both approaches, can give more comprehensive and accurate perspectives on the mechanism of the reaction between OP and AChE. The results show that the length of alkyl, and the electronegative of substituent on phenyl of OP have significant effects on the AChE activity, whereas, the hydrophobicity of OP has little influence. The steric and electronic properties of OP have a dominant influence on the reaction between OP and AChE.

  3. Quantitative structure-activity relationships for nasal pungency thresholds of volatile organic compounds.

    Science.gov (United States)

    Hau, K M; Connell, D W; Richardson, B J

    1999-01-01

    A model was developed for describing the triggering of nasal pungency in humans, based on the partition of volatile organic compounds (VOCs) between the air phase and the biophase. Two partition parameters are used in the model: the water-air partition coefficient and the octanol-water partition coefficient. The model was validated using data from the literature, principally on alcohols, acetates and ketones. The model suggests that all test compounds, regardless of their chemical functional groups, bind to a common receptor site within the hydrophobic interior of the bilayer membrane of the trigeminal nerve endings. There is probably only a slight, non-specific interaction between the VOC molecule and the receptor molecule, whereas this type of non-specific interaction for the detection of odor is much stronger. In practical terms, the suggestion that all VOCs share a common irritation receptor site implies that nasal-pungency thresholds of individual VOCs may be additive. Quantitative structure-activity relationships (QSARs) for nasal-pungency thresholds were also developed from the model, which can be used to predict nasal-pungency thresholds of common VOCs. Although the present model does not offer additional precision over that of M.H. Abraham et al., 1996, Fundam. Appl. Toxicol. 31, 71-76, it requires fewer descriptors and offers a physiological basis to the QSAR. Another advantage of the present model is that it also provides a basis for comparison between the olfactory process and nasal pungency.

  4. Organic compounds containing methoxy and cyanoacrylic acid: Synthesis, characterization, crystal structures, and theoretical studies

    Energy Technology Data Exchange (ETDEWEB)

    Khalaji, A. D., E-mail: alidkhalaji@yahoo.com [Golestan University, Department of Chemistry, Faculty of Science (Iran, Islamic Republic of); Maddahi, E. [Iran University of Science & Technology, Ms.C Educated, Department of Chemistry (Iran, Islamic Republic of); Dusek, M.; Fejfarova, K. [Institute of Physics of the ASCR, v.v.i. (Czech Republic); Chow, T. J. [Academia Sinica, Institute of Chemistry (China)

    2015-12-15

    Metal-free organic compounds 24-SC ((E)-2-cyano-3-(2,4-dimethoxyphenyl)acrylic acid) and 34-SC ((E)-2-cyano-3-(3,4-dimethoxyphenyl)acrylic acid), containing methoxy groups as a donor and the acrylic acid as an acceptor were synthesized and characterized by CHN, FT-IR, UV-Vis, {sup 1}H-NMR and single crystal X-ray diffraction and used as photosensitizers for the application of dye-sensitized solar cells (DSSC). The sensitizing characteristics of them were evaluated. Both compounds contain the natural molecule, its anionic form and the piperidinium cation and they differ by number of these molecules in the asymmetric unit. To get further insight into the effect of molecular structure on the performance of DSSC, their geometry and energies of HOMO and LUMO were optimized by density functional theory calculation at the B3LYP/6-31G(d) level with Gaussian 03. Overall conversion efficiencies of 0.78 under full sunlight irradiation are obtained for DSSCs based on the new metal-free organic dyes 24-SC and 34-SC.

  5. New 1,3,4-thiadiazole compounds including pyrazine moiety: Synthesis, structural properties and antimicrobial features

    Science.gov (United States)

    Gür, Mahmut; Şener, Nesrin; Muğlu, Halit; Çavuş, M. Serdar; Özkan, Osman Emre; Kandemirli, Fatma; Şener, İzzet

    2017-07-01

    In the study, some new 1,3,4-thiadiazole compounds were synthesized and we have reported identification of the structures by using UV-Vis, FT-IR, 1H NMR, 13C NMR and Mass spectroscopic methods. Antimicrobial activities of the compounds against three microorganisms, namely, Candida albicans ATCC 26555, Staphylococcus aureus ATCC 9144, and Escherichia coli ATCC 25922 were investigated by using disk diffusion method. These thiadiazoles exhibited an antimicrobial activity against Staphylococcus aureus and Candida albicans. The experimental data was supported by the quantum chemical calculations. Density functional theory (DFT) calculations were carried out to obtain the ground state optimized geometries of the molecules using the B3LYP, M06 and PBE1PBE methods with 3-21 g, 4-31 g, 6-311++g(2d,2p), cc-pvtz and cc-pvqz basis sets in the different combinations. Frontier molecular orbitals (FMOs) energies, band gap energies and some chemical reactivity parameters were calculated by using the aforementioned methods and basis sets, and the results were also compared with the experimental UV-Vis data.

  6. Dimers of nineteen-electron sandwich compounds: Crystal and electronic structures, and comparison of reducing strengths

    KAUST Repository

    Mohapatra, Swagat Kumar

    2014-10-03

    The dimers of some Group 8 metal cyclopentadienyl/ arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the Xray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central C-C σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these C-C bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2]2, rather similar (-1.97 to-2.15 V vs. FeCp2 +/0 in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.

  7. Synthesis, Structure, and Reactivity of Anionic sp(2) -sp(3) Diboron Compounds: Readily Accessible Boryl Nucleophiles.

    Science.gov (United States)

    Pietsch, Sabrina; Neeve, Emily C; Apperley, David C; Bertermann, Rüdiger; Mo, Fanyang; Qiu, Di; Cheung, Man Sing; Dang, Li; Wang, Jianbo; Radius, Udo; Lin, Zhenyang; Kleeberg, Christian; Marder, Todd B

    2015-05-04

    Lewis base adducts of tetra-alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2 pin2 ), have been proposed as the active source of nucleophilic boryl species in metal-free borylation reactions. We report the isolation and detailed structural characterization (by solid-state and solution NMR spectroscopy and X-ray crystallography) of a series of anionic adducts of B2 pin2 with hard Lewis bases, such as alkoxides and fluoride. The study was extended to alternative Lewis bases, such as acetate, and other diboron reagents. The B(sp(2) )-B(sp(3) ) adducts exhibit two distinct boron environments in the solid-state and solution NMR spectra, except for [(4-tBuC6 H4 O)B2 pin2 ](-) , which shows rapid site exchange in solution. DFT calculations were performed to analyze the stability of the adducts with respect to dissociation. Stoichiometric reaction of the isolated adducts with two representative series of organic electrophiles-namely, aryl halides and diazonium salts-demonstrate the relative reactivities of the anionic diboron compounds as nucleophilic boryl anion sources.

  8. Electronic structures of melatonin and related compounds studied by photoelectron spectroscopy

    CERN Document Server

    Kubota, M

    2003-01-01

    Melatonin is a hormone structurally regarded as being composed of a 5-methoxyindole group and an N-ethylacetamide group; its various physiological activities have attracted a great deal of attention recently. The gas phase He(I) photoelectron spectra of melatonin (M) and its related compounds including N-acetylserotonin have been studied with the aid of molecular orbital calculations. The first photoelectron spectral band group of compound M is ascribed to ionizations from the two pi orbitals localized on the methoxyindole group. The second band group is quite complicated and is regarded as being composed of several bands. The lower energy part of the second band group is ascribed to the three orbitals relevant to the third highest occupied pi orbital of 5-methoxyindole and the highest occupied pi and the n sub C sub = sub 0 orbitals of N-ethylacetamide. The interactions among the three orbitals have been found to operate on the basis of the molecular orbital calculations; these interactions depend strongly o...

  9. Magnetic properties and interfacial characteristics of all-epitaxial Heusler-compound stacking structures

    Science.gov (United States)

    Yamada, S.; Honda, S.; Hirayama, J.; Kawano, M.; Santo, K.; Tanikawa, K.; Kanashima, T.; Itoh, H.; Hamaya, K.

    2016-09-01

    We study magnetic properties and interfacial characteristics of all-epitaxial D 03-Fe3Si /L 21 - Fe3 -xMnxSi /L 21-Co2FeSi Heusler-compound trilayers grown on Ge(111) by room-temperature molecular beam epitaxy. We find that the magnetization reversal processes can be intentionally designed by changing the chemical composition of the intermediate Fe3 -xMnxSi layers because of their tunable ferromagnetic-paramagnetic phase-transition temperature. From first-principles calculations, interfacial half metallicity in the Co2FeSi layer is nearly expected when the sequence of stacking layers along of the Fe2MnSi /Co2FeSi interface includes the atomic row of L 21 - or B 2 -ordered structures. We believe that Co2FeSi /Fe2MnSi /Co2FeSi trilayer systems stacked along will open a new avenue for high-performance current-perpendicular-to-plane giant magnetoresistive devices with Heusler compounds.

  10. Ab initio structure determination of new compound Li 4CaB 2O 6

    Science.gov (United States)

    Wu, L.; Wang, C.; Chen, X. L.; Li, X. Z.; Xu, Y. P.; Cao, Y. G.

    2004-06-01

    A new compound, Li 4CaB 2O 6, has been synthesized by solid-state reaction and its structure has been determined from powder X-ray diffraction data by direct methods. The refinement was carried out using the Rietveld methods and the final refinement converged with Rp=10.4%, Rwp=14.2%, Rexp=4.97%. This compound belongs to the orthorhombic space group Pnnm, with lattice parameters a=9.24036(9) Å, b=8.09482(7) Å, and c=3.48162(4) Å. Fundamental building units are isolated [BO 3] 3- anionic groups, which are all parallel to the a- b plane stacked along the c-axis. The Ca atoms are six-coordinated by the O atoms to form octahedral coordination polyhedra, which are joined together through edges along the c-axis, forming infinitely long three-dimensional chains. The Li atoms have a four-fold and a five-fold coordination with O atoms that lead to complex Li-O-Li chains that also extend along the c-axis. The infrared spectrum of Li 4CaB 2O 6 was also studied, which is consistent with the crystallographic study.

  11. Electronic structures of melatonin and related compounds studied by photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, Mari. E-mail: marik@hc.cc.keio.ac.jp; Kobayashi, Tsunetoshi

    2003-02-01

    Melatonin is a hormone structurally regarded as being composed of a 5-methoxyindole group and an N-ethylacetamide group; its various physiological activities have attracted a great deal of attention recently. The gas phase He(I) photoelectron spectra of melatonin (M) and its related compounds including N-acetylserotonin have been studied with the aid of molecular orbital calculations. The first photoelectron spectral band group of compound M is ascribed to ionizations from the two {pi} orbitals localized on the methoxyindole group. The second band group is quite complicated and is regarded as being composed of several bands. The lower energy part of the second band group is ascribed to the three orbitals relevant to the third highest occupied {pi} orbital of 5-methoxyindole and the highest occupied {pi} and the n{sub C=0} orbitals of N-ethylacetamide. The interactions among the three orbitals have been found to operate on the basis of the molecular orbital calculations; these interactions depend strongly on the conformations. The high energy end of the second band group is relevant to the {pi} orbital mainly localized on the 5-methoxyindole group and is ascribed to the fourth highest occupied {pi} orbital of 5-methoxyindole.

  12. Crystal structure of a new hybrid compound based on an iodido-plumbate(II) anionic motif.

    Science.gov (United States)

    Mokhnache, Oualid; Boughzala, Habib

    2016-01-01

    Crystals of the one-dimensional organic-inorganic lead iodide-based compound catena-poly[bis-(piperazine-1,4-diium) [[tetra-iodido-plumbate(II)]-μ-iodido] iodide monohydrate], (C4N2H12)2[PbI5]I·H2O, were obtained by slow evaporation at room temperature of a solution containing lead iodide and piperazine in a 1:2 molar ratio. Inorganic lead iodide chains, organic (C4N2H12)(2+) cations, water mol-ecules of crystallization and isolated I(-) anions are connected through N-H⋯·I, N-H⋯OW and OW-H⋯I hydrogen-bond inter-actions. Zigzag chains of corner-sharing [PbI6](4-) octa-hedra with composition [PbI4/1I2/2](3-) running parallel to the a axis are present in the structure packing.

  13. Exploring the structural requirements for jasmonates and related compounds as novel plant growth regulators

    Science.gov (United States)

    Chen, Ke-Xian

    2009-01-01

    Jasmonates and related compounds have been highlighted recently in the field of plant physiology and plant molecular biology due to their significant regulatory roles in the signaling pathway for the diverse aspects of plant development and survival. Though a considerable amount of studies concerning their biological effects in different plants have been widely reported, the molecular details of the signaling mechanism are still poorly understood. This review sheds new light on the structural requirements for the bioactivity/property of jasmonic acid derivatives in current computational perspective, which differs from previous research that mainly focus on their biological evaluation, gene and metabolic regulation and the enzymes in their biosynthesis. The computational results may contribute to further understanding the mechanism of drug-receptor interactions in their signaling pathway and designing novel plant growth regulators as high effective ecological pesticides. PMID:20009552

  14. Low dimentional magnetic properties of compounds belonging to the CrVO{sub 4}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Law, Joseph M. [Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Department of Physics Loughborough University, Loughborough, Leics, LE11 3TU (United Kingdom); Kremer, Reinhard K. [Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)

    2011-07-01

    Compounds with the ABX{sub 4} composition exhibit a range of different magnetic properties. In recent years we have concentrated on only those adopting the CrVO{sub 4}-type structure, where we have a magnetic atom occupying the A position and a diamagnetic only atom within the B position. The A atom is housed within a distorted octahedral environment, the AO{sub 6} units are edge sharing and form buckled ribbon chains along the c-axis. The B atoms are contained within tetrahedral Oxygen environments which bridge the ribbon chains. We are present first results on the magnetic properties of some selected of this series which show, multiferroic behavior, spin-Peierls transitions and conventional long-range magnetic ordering.

  15. Compound grating structures in photonic crystals for resonant excitation of azobenzene

    DEFF Research Database (Denmark)

    Jahns, Sabrina; Kallweit, Christine; Adam, Jost

    -difference time-domain (FDTD) calculations for determination of resonance positions and electric field strengths in compound grating structures. By superimposing two single-period gratings a photonic crystal can be designed supporting multiple guided mode resonances suitable to switch azobenzenes between...... is small and thus a high excitation light intensity is required. We investigate the enhancement of the local energy density using periodically nanostructured surfaces in a high refractive index material. Such photonic crystals support quasi-guided modes visible as resonances in the reflection as well...... as in the transmission light spectrum. These guided modes have field contributions decaying exponentially in the near field of the photonic crystal. Azobenzene immobilized on the photonic crystal surface will experience a significantly increased light intensity compared to non-resonant surfaces. We performed finite...

  16. Crystal structure of a new hybrid compound based on an iodidoplumbate(II anionic motif

    Directory of Open Access Journals (Sweden)

    Oualid Mokhnache

    2016-01-01

    Full Text Available Crystals of the one-dimensional organic–inorganic lead iodide-based compound catena-poly[bis(piperazine-1,4-diium [[tetraiodidoplumbate(II]-μ-iodido] iodide monohydrate], (C4N2H122[PbI5]I·H2O, were obtained by slow evaporation at room temperature of a solution containing lead iodide and piperazine in a 1:2 molar ratio. Inorganic lead iodide chains, organic (C4N2H122+ cations, water molecules of crystallization and isolated I− anions are connected through N—H...·I, N—H...OW and OW—H...I hydrogen-bond interactions. Zigzag chains of corner-sharing [PbI6]4− octahedra with composition [PbI4/1I2/2]3− running parallel to the a axis are present in the structure packing.

  17. Structure elucidation of organic compounds from natural sources using 1D and 2D NMR techniques

    Science.gov (United States)

    Topcu, Gulacti; Ulubelen, Ayhan

    2007-05-01

    In our continuing studies on Lamiaceae family plants including Salvia, Teucrium, Ajuga, Sideritis, Nepeta and Lavandula growing in Anatolia, many terpenoids, consisting of over 50 distinct triterpenoids and steroids, and over 200 diterpenoids, several sesterterpenoids and sesquiterpenoids along with many flavonoids and other phenolic compounds have been isolated. For Salvia species abietanes, for Teucrium and Ajuga species neo-clerodanes for Sideritis species ent-kaurane diterpenes are characteristic while nepetalactones are specific for Nepeta species. In this review article, only some interesting and different type of skeleton having constituents, namely rearranged, nor- or rare diterpenes, isolated from these species will be presented. For structure elucidation of these natural diterpenoids intensive one- and two-dimensional NMR techniques ( 1H, 13C, APT, DEPT, NOE/NOESY, 1H- 1H COSY, HETCOR, COLOC, HMQC/HSQC, HMBC, SINEPT) were used besides mass and some other spectroscopic methods.

  18. Structure and heat capacity of the NaCeF4 compound

    Institute of Scientific and Technical Information of China (English)

    Virgil Constantin; Ana-Maria Popescu

    2013-01-01

    This work continued our general research program on obtaining metallic cerium by electrodeposition from NaCeF4 dis-solved in different molten fluorides. The structure of NaCeF4 (cubic or hexagonal depending on the way of preparation) was estab-lished by DTA analysis, IR spectra and X-ray diffraction. The heat capacity (Cp) of NaCeF4 was measured by differential scanning calorimetry in the temperature range of 300-1093 K using the“step-method”. The Cp was fitted by an equation with a satisfactory re-sult. Heat capacity was compared with that calculated from the Neumann-Kopp rule (NKR) and the deviations observed were consis-tent with the stability of the NaCeF4 compound.

  19. Structure elucidation of new compounds from acidic treatment of the progestins gestodene and drospirenone.

    Science.gov (United States)

    Colombo, Diego; Bombieri, Gabriella; Lenna, Roberto; Marchini, Nicoletta; Modica, Emilia; Scala, Antonio

    2006-08-01

    Gestodene acidic treatment afforded a single rearrangement product, namely 13-beta-ethyl-18,19-dinorpregna-4,14,16-trien-3,20-dione 3, which was originated through HCl-catalyzed Rupe rearrangement. Drospirenone acidic treatment yielded two epimeric lactones by addition of HCl to the 6beta,7beta-cyclopropane ring, namely 7beta-(chloromethyl)-15beta,16beta-methylene-3-oxo-17beta-pregn-4-ene-21,17-carbolactone 4 and 7beta-(chloromethyl)-15beta,16beta-methylene-3-oxo-17alpha-pregn-4-ene-21,17-carbolactone 5. The structure of the compounds was assessed by spectroscopic and crystallographic methods.

  20. Compound grating structures in photonic crystals for resonant excitation of azobenzene

    DEFF Research Database (Denmark)

    Jahns, Sabrina; Kallweit, Christine; Adam, Jost;

    -difference time-domain (FDTD) calculations for determination of resonance positions and electric field strengths in compound grating structures. By superimposing two single-period gratings a photonic crystal can be designed supporting multiple guided mode resonances suitable to switch azobenzenes between...... is small and thus a high excitation light intensity is required. We investigate the enhancement of the local energy density using periodically nanostructured surfaces in a high refractive index material. Such photonic crystals support quasi-guided modes visible as resonances in the reflection as well...... as in the transmission light spectrum. These guided modes have field contributions decaying exponentially in the near field of the photonic crystal. Azobenzene immobilized on the photonic crystal surface will experience a significantly increased light intensity compared to non-resonant surfaces. We performed finite...

  1. The crystal structure of the LiAg 2In compound

    Science.gov (United States)

    Pavlyuk, V. V.; Dmytriv, G. S.; Chumak, I. V.; Ehrenberg, H.; Pauly, H.

    2005-11-01

    The newly established intermetallic compound LiAg 2In crystallizes in the MnCu 2Al-type structure ( Fm-3 m, Heusler phase) with a=6.5681(5) Å. The homogeneity range of this phase in the ternary Li-Ag-In phase diagram along the adjacent quasibinary cut Li 0.25(Ag 1-xIn x) 0.75 was determined by X-ray powder diffraction and extends from x˜0.33, Li 0.25Ag 0.50In 0.25, up to x˜0.44, Li 0.25Ag 0.42In 0.33. The homogeneity ranges of Heusler- and Zintl-type phases in the Li-Ag-In system are separated from each other by a broad heterogeneous region.

  2. Structural and property studies on metal-organic compounds with 3-D supramolecular network

    Science.gov (United States)

    Zhang, Qi-Ying; Ma, Ke-Fang; Xiao, Hong-Ping; Li, Xin-Hua; Shi, Qian

    2014-07-01

    Two carboxylato-bridged allomeric compounds, {[Cu2(dbsa)2(hmt) (H2O)4]1/2·2H2O}n (1), {[Ni(dbsa)(H2O)2]1/2[Ni(dbsa)(hmt)(H2O)2]1/2·2H2O}n (2) (H2dbsa=meso-2,3-dibromosuccinic acid, hmt=hexamethylenetetramine) have been synthesized and characterized by X-ray structral analyses. The metal ions have two kinds of coordination fashion in one unit, and bridged by carboxylate and hmt ligands along with weak interactions existing in the solid structure, forming a 3-D supramolecular network. Variable-temperature magnetic property studies reveal the existence of antiferromagnetic interactions in 1 and 2 with g=2.2, J1=-3.5 cm-1, J2=-2.8 cm-1 for 1, and g=2.1, J=-3.5 cm-1 for 2.

  3. Crystal structure of the ternary semiconductor compound thallium gallium sulfide, TlGaS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela)]. E-mail: gerzon@ula.ve; Mora, A.J. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Perez, F.V. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela); Departamento de Fisica, Facultad de Ciencias, Universidad del Zulia, Zulia (Venezuela); Gonzalez, J. [Centro de Estudios de Semiconductores, Departamento de Fisica, Facultad de Ciencias, Universidad de Los Andes, Merida 5101 (Venezuela)

    2007-04-01

    Thallium gallium sulfide, TlGaS{sub 2}, a semiconductor compound, was prepared by solid-state reaction technique. Its crystal structure was determined by single-crystal X-ray diffraction. This material crystallizes in the monoclinic system with space group C2/c (No. 15), Z=16 and unit cell parameters a=10.2990(8)A, b=10.2840(8)A, c=15.1750(18)A, {beta}=99.603(4){sup o}. The structural refinement converged to R(F)=0.0999, R(F{sup 2})=0.0764 and S=1.067. The structure consists of a three-dimensional arrangement of distorted TlS{sub 8} and GaS{sub 4} polyhedrons. Four GaS{sub 4} tetrahedra form adamantine-like units of the type Ga{sub 4}S{sub 10}, which in turn connect through the corners forming layers that run along the [100] direction.

  4. Optical absorption spectrum and electronic structure of multiferroic hexagonal YMnO3 compound

    Science.gov (United States)

    Lima, A. F.; Lalic, M. V.

    2017-02-01

    Optical absorption (OA) spectrum and electronic structure of the hexagonal YMnO3 compound have been investigated by employment of the first-principles calculations based on density functional theory. The calculations were performed upon the ferroelectric structure of the YMnO3, by testing various approximations of the exchange-correlation effects between the Mn d-electrons and considering two types of magnetic ordering of the Mn sub-lattice: (1) collinear anti-ferromagnetic order of the G-type and (2) non-collinear antiferromagnetic order that correspond to magnetic space group P63. The results demonstrate that satisfactory agreement between the theoretical and the experimental OA spectrum can be achieved only if both non-collinear anti-ferromagnetic order of the Mn spins and strong correlations between the Mn d-electrons are taken into account. The latter is found to be best described by effective Hubbard parameter Ueff = 2.55 eV. The principal features of the OA spectrum are interpreted in terms of calculated electronic structure. It is found that the most important, threshold 1.6 eV OA peak is generated by electron transitions from strongly hybridized occupied Mn d- and its neighboring in-plane O p-states to unoccupied Mn d-states. It is also concluded that the electronic gap (calculated as ∼1.1 eV) should be smaller than the optical one (∼1.6 eV).

  5. Constraints on Stress Components at the Internal Singular Point of an Elastic Compound Structure

    Science.gov (United States)

    Pestrenin, V. M.; Pestrenina, I. V.

    2017-03-01

    The classical analytical and numerical methods for investigating the stress-strain state (SSS) in the vicinity of a singular point consider the point as a mathematical one (having no linear dimensions). The reliability of the solution obtained by such methods is valid only outside a small vicinity of the singular point, because the macroscopic equations become incorrect and microscopic ones have to be used to describe the SSS in this vicinity. Also, it is impossible to set constraint or to formulate solutions in stress-strain terms for a mathematical point. These problems do not arise if the singular point is identified with the representative volume of material of the structure studied. In authors' opinion, this approach is consistent with the postulates of continuum mechanics. In this case, the formulation of constraints at a singular point and their investigation becomes an independent problem of mechanics for bodies with singularities. This method was used to explore constraints at an internal singular point (representative volume) of a compound wedge and a compound rib. It is shown that, in addition to the constraints given in the classical approach, there are also constraints depending on the macroscopic parameters of constituent materials. These constraints turn the problems of deformable bodies with an internal singular point into nonclassical ones. Combinations of material parameters determine the number of additional constraints and the critical stress state at the singular point. Results of this research can be used in the mechanics of composite materials and fracture mechanics and in studying stress concentrations in composite structural elements.

  6. Synthesis, Characterization, Crystal Structure and Quantum Chemical Calculation of Novel Compound 1,3-Dimethyl-2-ferrocenylmethylbenzimidazolium Iodide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jing; YANG Bing-Qin; ZHU Hai-Yan; LI Tao; WEN Zhen-Yi

    2006-01-01

    A novel benzimidazole derivative, 1,3-dimethyl-2-ferrocenylmethylbenzimidazolium iodide (1) was synthesized and characterized by elemental analysis, MS, 1H NMR and IR spectra. Its crystal structure was determined by X-ray single crystal diffraction, and the title compound belongs to monoclinic system with space group P2(1)/c.According to the crystal structure, the quantum chemistry calculation was performed by Gaussian 03 program, and full geometry optimizations of the title compound were carried out with DFT method at B3LYP/6-31G level. Its structure, stability, frontier molecular orbital components and net charge distribution were discussed.

  7. Toxic effects on and structure-toxicity relationships of phenylpropanoids, terpenes, and related compounds in Aedes aegypti larvae.

    Science.gov (United States)

    Santos, Sandra R L; Silva, Viviane B; Melo, Manuela A; Barbosa, Juliana D F; Santos, Roseli L C; de Sousa, Damião P; Cavalcanti, Sócrates C H

    2010-12-01

    In the search for toxic compounds against Aedes aegypti L. (Diptera: Culicidae) larvae, a collection of commercially available aromatic and aliphatic diversely substituted compounds were selected and evaluated. p-Cymene exhibited the highest larvicidal potency LC₅₀ = 51 ppm, whereas 1,8-cineole exhibited the lowest activity value LC₅₀ = 1419 ppm. To aid future work on the search for larvicidal compounds, the structure-toxicity relationships of this collection have been evaluated. The presence of lipophilic groups results in an overall increase in potency. In general, the presence of hydroxyl groups resulted in less potent compounds. However, methylation of such hydroxyls led to an overall increase in potency. The most potent compounds showed comparably good larvicidal activity in A. aegypti larvae as other terpenes, which we assume to be the result of the increased lipophilicity.

  8. Go/No-Go Procedure with Compound Stimuli: Effects of Training Structure on the Emergence of Equivalence Classes

    Science.gov (United States)

    Grisante, Priscila C.; Galesi, Fernanda L.; Sabino, Nathali M.; Debert, Paula; Arntzen, Erik; McIlvane, William J.

    2013-01-01

    When the matching-to-sample (MTS) procedure is used, different training structures imply differences in the successive discriminations required in training and test conditions. When the go/no-go procedure with compound stimuli is used, however, differences in training structures do not imply such differences. This study assessed whether the…

  9. SUPERSPACE-GROUP APPROACH TO THE MODULATED STRUCTURE OF THE INORGANIC MISFIT LAYER COMPOUND (LAS)1.14NBS2

    NARCIS (Netherlands)

    VANSMAALEN, S

    1991-01-01

    The structure of the inorganic misfit layer compound (LaS)1.14NbS2 is reanalysed in the superspace-group formalism, using the recent single-crystal x-ray diffraction data obtained by Meerschaut, Rabu and Rouxel. Structure refinements make it possible to determine the values of the modulation functio

  10. Structural, electronic and elastic properties of REIr2 (RE = Sc, Y and La) Laves phase compounds under pressure

    Science.gov (United States)

    Shrivastava, D.; Sanyal, S. P.

    2017-02-01

    The structural, electronic and elastic properties of REIr2 (RE = Sc, Y and La) type Laves phase compounds in C15 structure have been studied using full-potential linearized augmented plane wave method with generalized gradient approximation based on density functional theory. The ground state properties such as lattice constants are in good agreement with the experimental results. The electronic properties such as band structures, total and partial density of states confirm their metallic character. The pressure dependent behavior of density of states are also calculated and found that they are structurally stable. The elastic constants calculated as a function of pressure for all REIr2 (RE = Sc, Y and La) type compounds. The others secondary elasticity parameters are also reported. The results show that all REIr2 (RE = Sc, Y and La) compounds are ductile according to the analysis of B0/ G H and Cauchy's pressure.

  11. Interionic pair potentials and partial structure factors of compound-forming quaternary NaSn liquid alloy: First principle approach

    Indian Academy of Sciences (India)

    Anil Thakur; P K Ahluwalia

    2007-10-01

    In this paper formulae for partial structure factors have been used to study partial structure factors of compound-forming quaternary liquid alloys by considering Hoshino's m-component hard-sphere mixture, which is based on Percus-Yevic equation of Hiroike. Formulae are applied to NaSn (Na, Sn, NaSn, Na3Sn) which is considered as a quaternary liquid mixture with the formation of two compounds simultaneously. We have compared the total structure factors for ternary and quaternary alloys with experimental total structure factors which are found to be in good agreement. This suggests that, for suitable stoichiometric composition, two compounds are formed simultaneously. The hard-sphere diameters needed have been calculated using Troullier and Martins ab-initio pseudopotentials.

  12. EFFECTS OF Al CONTENT ON STRUCTURAL STABILITY AND MAGNETIC PROPERTIES OF Sm2 (Fe, Al) 17 COMPOUNDS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    Themagneticproperties of Sm2Fe17-xAlx(x=0,1,2,3)compoundsandtheirhydridesare systematically investigated. The results reveal that all compounds have the Th2Zn17-type structure. As the content of Al increases, the Curie temperature of Sm2(Fe, Al)17 compounds increases, and their saturation magnetization decreases. It is first discovered that the Curie temperatures of the hydrides of Sm2 (Fe, Al)17compounds measured from heating process are higher than those measured from cooling process, and their difference is denoted as △Tc* . The correlation between △Tc* and the structural stability of Sm2(Fe, Al)17 compounds as well as their corresponding hydrides is discussed.

  13. Branched peptide amphiphiles, related epitope compounds and self assembled structures thereof

    Science.gov (United States)

    Stupp, Samuel I.; Guler, Mustafa O.

    2008-11-18

    Branched peptide amphiphilic compounds incorporating one or residues providing a pendant amino group for coupling one or more epitope sequences thereto, such compounds and related compositions for enhanced epitope presentation.

  14. Synthesis, Crystal and Electronic Structure of the Quaternary Magnetic EuTAl4Si2 (T = Rh and Ir) Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Maurya, Arvind [Tata Institute of Fundamental Research; Thamizhavel, Arumugam [Tata Institute of Fundamental Research; Provino, Alessia [University of Genova; Pani, Marcella [University of Genova; Manfrinetti, Pietro [University of Genova; Paudyal, Durga [Ames Laboratory; Dhar, Sudesh Kumar [Tata Institute of Fundamental Research

    2014-01-22

    Single crystals of the quaternary europium compounds EuRhAl4Si2 and EuIrAl4Si2 were synthesized by using the Al–Si binary eutectic as a flux. The structure of the two quaternary compounds has been refined by single crystal X-ray diffraction. Both compounds are stoichiometric and adopt an ordered derivative of the ternary KCu4S3 structure type (tetragonal tP8, P4/mmm). The two compounds reported here represent the first example of a quaternary and truly stoichiometric 1:1:4:2 phase crystallizing with this structure type. In light of our present results, the structure of the BaMg4Si3 compound given in literature as representing a new prototype is actually isotypic with the KCu4S3 structure. Local spin density approximation including the Hubbard U parameter (LSDA + U) calculations show that Eu ions are in the divalent state, with a significant hybridization between the Eu 5d, Rh (Ir) 4d (5d), Si 3p and Al 3p states. Magnetic susceptibility measured along the [001] direction confirms the divalent nature of the Eu ions in EuRhAl4Si2 and EuIrAl4Si2, which order magnetically near 11 and 15 K, respectively.

  15. Synthesis, crystal structure and antibacterial activity of new highly functionalized ionic compounds based on the imidazole nucleus.

    Science.gov (United States)

    Bahnous, Mebarek; Bouraiou, Abdelmalek; Chelghoum, Meryem; Bouacida, Sofiane; Roisnel, Thierry; Smati, Farida; Bentchouala, Chafia; Gros, Philippe C; Belfaitah, Ali

    2013-03-01

    Several new highly functionalized imidazolium derivatives were synthesized, via appropriate synthetic routes, using imidazole, 1-methylimidazole and 2-phenyl-1-methylimidazole as key intermediates. The antibacterial activity of the prepared compounds was evaluated against: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella thipymurium using disk-diffusion and MIC methods. Crystal X-ray structures are reported for six compounds. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Weighted Feature Significance: A Simple, Interpretable Model of Compound Toxicity Based on the Statistical Enrichment of Structural Features

    OpenAIRE

    Huang, Ruili; Southall, Noel; Xia, Menghang; Cho, Ming-Hsuang; Jadhav, Ajit; Nguyen, Dac-Trung; Inglese, James; Tice, Raymond R.; Austin, Christopher P.

    2009-01-01

    In support of the U.S. Tox21 program, we have developed a simple and chemically intuitive model we call weighted feature significance (WFS) to predict the toxicological activity of compounds, based on the statistical enrichment of structural features in toxic compounds. We trained and tested the model on the following: (1) data from quantitative high–throughput screening cytotoxicity and caspase activation assays conducted at the National Institutes of Health Chemical Genomics Center, (2) dat...

  17. Synthesis and crystal structure of new K and Rb selenido/tellurido ferrate cluster compounds

    Energy Technology Data Exchange (ETDEWEB)

    Stueble, Pirmin; Berroth, Angela; Roehr, Caroline [Freiburg Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2016-08-01

    In the course of a systematic study of alkali iron chalcogenido salts containing clusters [Fe{sub 4}Q{sub 8}] a series of new mixed-valent potassium and rubidium selenido and tellurido ferrates(II/III) was synthesized by carefully heating the pure elements enclosed in sample tubes under an argon atmosphere up to maximum temperatures of 800-900 C. Their crystal structures have been determined by means of single crystal X-ray diffraction. The mixed-valent Fe{sup II/III} tellurido ferrates A{sub 7}[Fe{sub 4}Te{sub 8}] form three different structure types. All structures contain tetramers of four edge sharing [FeTe{sub 4}] tetrahedra, which are connected by common edges to form only slightly distorted tetrahedral [Fe{sub 4}Te{sub 8}]{sup 7-} anions ('stella quadrangula') with a [Fe{sub 4}Te{sub 4}] cubane core. In all cases, these anions are surrounded by 26 alkali cations, which are located at the eight corners and the midpoints of the six faces and 12 edges of a cube. The three crystal structures can thus be described by three different packings of cuboid moieties: The monoclinic rubidium compound Rb{sub 7}[Fe{sub 4}Te{sub 8}] (space group C2/c, a = 2000.16(7), b = 897.79(3), c = 1768.12(6) pm, β = 117.4995(10) , Z = 4, R1 = 0.0296) is isotypic to the known cesium tellurido and sulfido ferrates Cs{sub 7}[Fe{sub 4}(S/Te){sub 8}]. Depending on the temperature, K{sub 7}[Fe{sub 4}Te{sub 8}] forms two different but closely related new structure types: The tetragonal r.t. modification (space group P4{sub 2}/nmc, a = 1222.25(14), c = 872.1(2) pm, Z = 2, R1 = 0.0583) crystallizes in a supergroup of the orthorhombic l.t. (100 K) form (space group Pbcn, a = 1715.5, b = 866.76(3), c = 1715.50(7) pm, Z = 4, R1 = 0.0160). In all structures, the cluster centered cubes are stacked to form columns along the short (∼ 870 pm) axis. These columns are themselves densely packed with 4 (both K compounds) and 6 (A = Rb) adjacent face-sharing columns. According to these

  18. First-principles study of Al2Sm intermetallic compound on structural, mechanical properties and electronic structure

    Science.gov (United States)

    Lin, Jingwu; Wang, Lei; Hu, Zhi; Li, Xiao; Yan, Hong

    2017-02-01

    The structural, thermodynamic, mechanical and electronic properties of cubic Al2Sm intermetallic compound are investigated by the first-principles method on the basis of density functional theory. In light of the strong on-site Coulomb repulsion between the highly localized 4f electrons of Sm atoms, the local spin density approximation approach paired with additional Hubbard terms is employed to achieve appropriate results. Moreover, to examine the reliability of this study, the experimental value of lattice parameter is procured from the analysis of the TEM image and diffraction pattern of Al2Sm phase in the AZ31 alloy to verify the authenticity of the results originated from the computational method. The value of cohesive energy reveals Al2Sm to be a stable in absolute zero Kelvin. According to the stability criteria, the subject of this work is mechanically stable. Afterward, elastic moduli are deduced by performing Voigt-Reuss-Hill approximation. Furthermore, elastic anisotropy and anisotropy of sound velocity are discussed. Finally, the calculation of electronic density of states is implemented to explore the underlying mechanism of structural stability.

  19. Spectroscopic and structural investigation on intermediates species structurally associated to the tricyclic bisguanidine compound and to the toxic agent, saxitoxin

    Science.gov (United States)

    Romani, Davide; Tsuchiya, Shigeki; Yotsu-Yamashita, Mari; Brandán, Silvia Antonia

    2016-09-01

    In the present work, we have studied the structural, topological and spectroscopic properties of five cyclic and of open chain species derived from tricyclic bisguanidine compound in gas and aqueous phases combining the DFT calculations with the experimental infrared and 1H NMR, 13C NMR and UV-visible spectra. These species are members of the saxitoxin family and they were recently synthesized by Tsuchiya et al. (Chemistry. A European Journal, 21 (2015) 7835-7840). Here, the self consistent reaction force (SCRF) calculations were employed in aqueous medium to study the solvation energies by using the polarized continuum (PCM) and solvation (SM) models. All the calculations were performed with the 6-31G* and 6-311++G** basis sets. The atomic charges, electrostatic potentials, bond order, stabilization energy, topological properties suggest the structural connection between the cyclic cationic and saxitoxin species while the electrophilicity and nucleophilicity indexes could be one of the explanations for the Nav blocking activities of these species. The complete vibrational assignments for all the species are reported. The predicted spectra present a reasonable concordance with the corresponding experimental ones.

  20. On the crystal structure and physical properties of the UFeSb{sub 2} compound

    Energy Technology Data Exchange (ETDEWEB)

    Gonçalves, A.P., E-mail: apg@ctn.ist.utl.pt [C2TN, Instituto Superior Técnico, Universidade de Lisboa, CFMC-UL, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Henriques, M.S.; Waerenborgh, J.C. [C2TN, Instituto Superior Técnico, Universidade de Lisboa, CFMC-UL, Campus Tecnológico e Nuclear, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal); Curlik, I.; Il’kovič, S.; Reiffers, M. [Faculty of Humanities and Natural Sciences, Prešov University, 081 16 Prešov (Slovakia)

    2014-12-15

    Highlights: • Polycrystalline UFeSb{sub 2} was prepared by conventional arc-melting route. • An accurate crystal structure characterization of UFeSb{sub 2} was made. • UFeSb{sub 2} has a ferromagnetic-type transition at 31(1) K. • The ferromagnetic-like properties of UFeSb{sub 2} are determined by the U-sublattice. • Specific heat shows that UFeSb{sub 2} is a medium correlated electron system. - Abstract: The UFeSb{sub 2} ternary uranium antimonide has been prepared by arc-melting, followed by annealing at 750 °C for 1 week, and was characterized by means of powder X-ray diffraction, electrical resistivity, magnetization, Mössbauer spectroscopy and specific heat measurements. UFeSb{sub 2} crystallizes in the tetragonal HfCuSi{sub 2}-type structure (space group P4/nmm, a = 0.43249(3) nm, c = 0.90962(7) nm), with the U, Fe and Sb atoms at the positions of Hf (2c), Cu (2b) and Si (2a and 2c), respectively. The nearest neighbor atoms of U are at distances close to or higher than the metallic radii sum, pointing to the possibility of a non negligible U magnetic moment, which contrasts with the very short Fe–Sb1 distances that indicate a probable collapse of Fe magnetic moments. The UFeSb{sub 2} undergoes a ferromagnetic-type transition at 31(1) K with a small saturation magnetization, suggesting for this compound a non-negligible U hybridization, itinerant magnetism and/or a complex magnetic structure. Mössbauer spectroscopy confirms that the magnetism is ruled by the U sub-lattice, with neither long-range magnetic ordering nor standard spin-glass behavior of the iron sub-lattice. The Sommerfeld coefficient of the electronic specific heat is γ = 51(1) mJ/mol K{sup 2}, which classifies this compound as a medium correlated system.

  1. Structure of a cation-bound multidrug and toxic compound extrusion transporter

    Energy Technology Data Exchange (ETDEWEB)

    He, Xiao; Szewczyk, Paul; Karyakin, Andrey; Evin, Mariah; Hong, Wen-Xu; Zhang, Qinghai; Chang, Geoffrey (Scripps)

    2010-10-26

    Transporter proteins from the MATE (multidrug and toxic compound extrusion) family are vital in metabolite transport in plants, directly affecting crop yields worldwide. MATE transporters also mediate multiple-drug resistance (MDR) in bacteria and mammals, modulating the efficacy of many pharmaceutical drugs used in the treatment of a variety of diseases. MATE transporters couple substrate transport to electrochemical gradients and are the only remaining class of MDR transporters whose structure has not been determined. Here we report the X-ray structure of the MATE transporter NorM from Vibrio cholerae determined to 3.65 {angstrom}, revealing an outward-facing conformation with two portals open to the outer leaflet of the membrane and a unique topology of the predicted 12 transmembrane helices distinct from any other known MDR transporter. We also report a cation-binding site in close proximity to residues previously deemed critical for transport. This conformation probably represents a stage of the transport cycle with high affinity for monovalent cations and low affinity for substrates.

  2. Forming method of micro heat pipe with compound structure of sintered wick on grooved substrate

    Science.gov (United States)

    Li, Xibing; Li, Mingjian; Li, Ming; Wu, Ruchen; Wan, Yingsi; Cheng, Tian

    2016-03-01

    Micro heat pipes (MHPs) with excellent heat transfer performance have been the ideal radiating components to meet increasingly higher requirements posed by high heat-flux products. Based on MHPs' working principle, this study deduced capillary limit of a novel MHP with compound structure of sintered wick on grooved substrate, and probed into its forming mechanism: first, high-speed oil-filled spinning was applied to fabricating micro grooves, with optimal spinning and drawing speeds determined; then a mini-type vibration machine was used to help fill copper powders fast and uniformly, with appropriate sintering temperature and time fixed; the manufacturing method that integrates vacuum-pumping-cold-welding with secondary-degassing-cold-welding to increase vacuumizing efficiency. The results of experiments on its heat transfer performance show that the MHPs with sintered-wick-on-grooved-substrate structure fabricated through the proposed forming method can not only acquire much better heat transfer performance, but have advantages such as higher productivity and lower cost.

  3. Crystal structure and superconductivity in the Th-doped LaPtSi compounds

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.Y.; Sung, H.H.; Syu, K.J. [Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan (China); Lee, W.H., E-mail: whlee@phy.ccu.edu.t [Department of Physics, National Chung Cheng University, Ming-Hsiung, Chia-Yi, Taiwan (China)

    2010-12-15

    As observed with X-ray powder diffraction, the tetragonal structure of the parent compound LaPtSi, which crystallizes in the LaPtSi-type structure with space group I4{sub 1}md, is retained in (La{sub 1-x}Th{sub x})PtSi up to the solubility limit near x = 0.5. By considering the size factor of Hume-Rothery theory of alloy phase formation, it is not marvelous that the extensive solid solutions cannot be fully completed in (La{sub 1-x}Th{sub x})PtSi. We present the room temperature powder X-ray diffraction patterns, the room temperature lattice parameters and the dc magnetic susceptibility between 1.8 and 4.0 K for three single phase polycrystalline samples in (La{sub 1-x}Th{sub x})PtSi with x 0, 0.25 and 0.50. The refined lattice parameters show that both the a-axis and the volume of the unit cell v contract clearly, though the c-axis gives a less percentage expansion due to doping with thorium. It is found that the change in T{sub c} with x is similar to the change in the lattice parameter a or v, which indicates that the stiffening of the lattice under pressure has a dominant effect on the decrease in T{sub c} in this system.

  4. Retinular fine structure in compound eyes of diurnal and nocturnal sphingid moths.

    Science.gov (United States)

    Eguchi, E

    1982-01-01

    Retinular fine structure has been compared in the superposition compound eyes of three sphingid moths, one nocturnal, Cechenena, and two diurnal, Cephonodes and Macroglossum. Cechenena and Cephonodes have tiered retinas with three kinds of retinular cells: two distal, six regular and one basal. The distal retinular cells in Cechenena are special in having a complex partially intracellular rhabdomere not present in Cephonodes. Macroglossum lacks the distal retinular cell. In Cephonodes a unique rhabdom type, formed by the six regular retinular cells in the middle region of the retinula, is divided into three separate longitudinal plates arranged closely parallel to one another. Their constituent microvilli are consequently all nearly unidirectional. The ratio of rhabdom volume to retinular cell volume in the two diurnal sphingids is 10-27%; this is about the same as that (25%) of skipper butterflies, but significantly smaller than in the nocturnal Cechenena (60%). In the diurnal sphingids retinular cell membranes show elongate meandering profiles with septate junctions between adjacent retinular cells. From the comparative fine structure of their eyes the diurnal sphingids and the skippers would appear to be phylogenetically closely related.

  5. Synthesis and crystal structure of the coordination compound of pyridoxine with manganese sulfate

    Science.gov (United States)

    Furmanova, N. G.; Verin, I. A.; Shyityeva, N.; Sulaimankulov, K. S.; Berdalieva, Zh.; Resnyanskii, V. F.; Duishenbaeva, A. T.

    2011-11-01

    The reaction of pyridoxine with manganese sulfate in an aqueous solution gave the coordination compound MnSO4 · 2C8H11O3N · 2H2O ( I). The structure of I was determined from single-crystal X-ray diffraction data. In the centrosymmetric complex (sp. gr. Pbar 1, Z = 1), the Mn atom is coordinated by two pyridoxine molecules and two water molecules, thus adopting an octahedral coordination. The sulfate anion is also at a center of symmetry and, consequently, is disordered. The pyridoxine molecules are coordinated to the metal atom through the oxygen atoms of the deprotonated hydroxyl group and the CH2OH group that retains the hydrogen atom. The nitrogen atom is protonated in such a way that the heterocycle assumes a pyridinium character. The crystal structure also contains six water molecules of crystallization. A thermogravimetric study showed that the decomposition of I occurs in several successive steps, such as dehydration, the combustion of organic ligands, and the formation of an inorganic residue.

  6. Structure-activity relations in binding of perfluoroalkyl compounds to human thyroid hormone T3 receptor.

    Science.gov (United States)

    Ren, Xiao-Min; Zhang, Yin-Feng; Guo, Liang-Hong; Qin, Zhan-Fen; Lv, Qi-Yan; Zhang, Lian-Ying

    2015-02-01

    Perfluoroalkyl compounds (PFCs) have been shown to disrupt thyroid functions through thyroid hormone receptor (TR)-mediated pathways, but direct binding of PFCs with TR has not been demonstrated. We investigated the binding interactions of 16 structurally diverse PFCs with human TR, their activities on TR in cells, and the activity of perfluorooctane sulfonate (PFOS) in vivo. In fluorescence competitive binding assays, most of the 16 PFCs were found to bind to TR with relative binding potency in the range of 0.0003-0.05 compared with triiodothyronine (T3). A structure-binding relationship for PFCs was observed, where fluorinated alkyl chain length longer than ten, and an acid end group were optimal for TR binding. In thyroid hormone (TH)-responsive cell proliferation assays, PFOS, perfluorohexadecanoic acid, and perfluorooctadecanoic acid exhibited agonistic activity by promoting cell growth. Furthermore, similar to T3, PFOS exposure promoted expression of three TH upregulated genes and inhibited three TH downregulated genes in amphibians. Molecular docking analysis revealed that most of the tested PFCs efficiently fit into the T3-binding pocket in TR and formed a hydrogen bond with arginine 228 in a manner similar to T3. The combined in vitro, in vivo, and computational data strongly suggest that some PFCs disrupt the normal activity of TR pathways by directly binding to TR.

  7. Growth and Electronic Structure of Heusler Compounds for Use in Electron Spin Based Devices

    Science.gov (United States)

    Patel, Sahil Jaykumar

    Spintronic devices, where information is carried by the quantum spin state of the electron instead of purely its charge, have gained considerable interest for their use in future computing technologies. For optimal performance, a pure spin current, where all electrons have aligned spins, must be generated and transmitted across many interfaces and through many types of materials. While conventional spin sources have historically been elemental ferromagnets, like Fe or Co, these materials pro duce only partially spin polarized currents. To increase the spin polarization of the current, materials like half-metallic ferromagnets, where there is a gap in the minority spin density of states around the Fermi level, or topological insulators, where the current transport is dominated by spin-locked surface states, show promise. A class of materials called Heusler compounds, with electronic structures that range from normal metals, to half metallic ferromagnets, semiconductors, superconductors and even topological insulators, interfaces well with existing device technologies, and through the use of molecular beam epitaxy (MBE) high quality heterostructures and films can be grown. This dissertation examines the electronic structure of surfaces and interfaces of both topological insulator (PtLuSb-- and PtLuBi--) and half-metallic ferromagnet (Co2MnSi-- and Co2FeSi--) III-V semiconductor heterostructures. PtLuSb and PtLuBi growth by MBE was demonstrated on Alx In1--xSb (001) ternaries. PtLuSb (001) surfaces were observed to reconstruct with either (1x3) or c(2x2) unit cells depending on Sb overpressure and substrate temperature. viii The electronic structure of these films was studied by scanning tunneling microscopy/spectroscopy (STM/STS) and photoemission spectroscopy. STS measurements as well as angle resolved photoemission spectropscopy (ARPES) suggest that PtLuSb has a zero-gap or semimetallic band structure. Additionally, the observation of linearly dispersing surface

  8. Patterson-function direct methods for structure determination of organic compounds from powder diffraction data. XVI.

    Science.gov (United States)

    Rius, Jordi

    2011-01-01

    A new type of direct methods (DM) called Patterson-function DM are presented that directly explore the Patterson instead of the modulus function. Since they work with the experimental intensities, they are particularly well suited for handling powder diffraction data. These methods are based on the maximization of the sum function S(P) ∝ ∑H(I(H)-)G(-H)(Φ) in terms of the Φ phases of the structure factors. The quantity accessible from the experiment is I(H), the equidistributed multiplet intensity of reflection H, and is the average intensity taken over all non-systematically absent reflections. G(-H)(Φ) is the calculated structure-factor amplitude of the squared structure that includes the positivity and the atomicity of the density function in its definition. The S(P) sum function can be optimized with the Patterson-function tangent formula (TF) using a variant of the S-FFT algorithm [Rius et al. (2007), Acta Cryst. A63, 131-134]. It is important that overlapped reflections also participate in the phase refinement, so that not only the resolved reflections but the whole pattern contribute decisively to the refinement. The increase in effective data resolution minimizes Fourier series termination effects and improves the accuracy of G(Φ). The Patterson-function TF has been applied to synchrotron powder data of various organic compounds. In all cases the molecules were easily identified in the respective Fourier maps. By way of illustration the method is applied to synchrotron powder data of a dimer formed by 30 symmetry-independent non-H atoms. Since single-crystal data may be regarded as overlap-free powder data, it is clear that Patterson-function DM can cope with powder and single-crystal data.

  9. The atomic structure of low-index surfaces of the intermetallic compound InPd

    Energy Technology Data Exchange (ETDEWEB)

    McGuirk, G. M.; Ledieu, J.; Gaudry, É.; Weerd, M.-C.; Fournée, V. de, E-mail: vincent.fournee@univ-lorraine.fr [Institut Jean Lamour (UMR 7198 CNRS-Université de Lorraine), Parc de Saurupt, F-54011 Nancy Cedex (France); Hahne, M.; Gille, P. [Department of Earth and Environmental Sciences, Crystallography Section, Ludwig-Maximilians-Universität München, Theresienstrasse 41, D-80333 München (Germany); Ivarsson, D. C. A.; Armbrüster, M. [Faculty of Natural Sciences, Institute of Chemistry, Materials for Innovative Energy Concepts, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Ardini, J.; Held, G. [Department of Chemistry, University of Reading, Reading RG6 6AD (United Kingdom); Diamond Light Source Ltd, Didcot OX11 0DE (United Kingdom); Maccherozzi, F. [Diamond Light Source Ltd, Didcot OX11 0DE (United Kingdom); Bayer, A. [Lehrstuhl für Physikalische Chemie II, Universität Erlangen-Nürnberg, Egerlandstraße 3, D-91058 Erlangen (Germany); Lowe, M. [Surface Science Research Centre and Department of Physics, The University of Liverpool, Liverpool L69 3BX (United Kingdom); Pussi, K. [Department of Mathematics and Physics, Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland); Diehl, R. D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States)

    2015-08-21

    The intermetallic compound InPd (CsCl type of crystal structure with a broad compositional range) is considered as a candidate catalyst for the steam reforming of methanol. Single crystals of this phase have been grown to study the structure of its three low-index surfaces under ultra-high vacuum conditions, using low energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). During surface preparation, preferential sputtering leads to a depletion of In within the top few layers for all three surfaces. The near-surface regions remain slightly Pd-rich until annealing to ∼580 K. A transition occurs between 580 and 660 K where In segregates towards the surface and the near-surface regions become slightly In-rich above ∼660 K. This transition is accompanied by a sharpening of LEED patterns and formation of flat step-terrace morphology, as observed by STM. Several superstructures have been identified for the different surfaces associated with this process. Annealing to higher temperatures (≥750 K) leads to faceting via thermal etching as shown for the (110) surface, with a bulk In composition close to the In-rich limit of the existence domain of the cubic phase. The Pd-rich InPd(111) is found to be consistent with a Pd-terminated bulk truncation model as shown by dynamical LEED analysis while, after annealing at higher temperature, the In-rich InPd(111) is consistent with an In-terminated bulk truncation, in agreement with density functional theory (DFT) calculations of the relative surface energies. More complex surface structures are observed for the (100) surface. Additionally, individual grains of a polycrystalline sample are characterized by micro-spot XPS and LEED as well as low-energy electron microscopy. Results from both individual grains and “global” measurements are interpreted based on comparison to our single crystals findings, DFT calculations and previous literature.

  10. Effects of dilute aqueous NaCl solution on caffeine aggregation

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Bhanita; Paul, Sandip, E-mail: sandipp@iitg.ernet.in [Department of Chemistry, Indian Institute of Technology, Guwahati 781039, Assam (India)

    2013-11-21

    The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

  11. Effects of dilute aqueous NaCl solution on caffeine aggregation

    Science.gov (United States)

    Sharma, Bhanita; Paul, Sandip

    2013-11-01

    The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

  12. Structure and Potential Cellular Targets of HAMLET-like Anti-Cancer Compounds made from Milk Components.

    Science.gov (United States)

    Rath, Emma M; Duff, Anthony P; Håkansson, Anders P; Vacher, Catherine S; Liu, Guo Jun; Knott, Robert B; Church, William Bret

    2015-01-01

    The HAMLET family of compounds (Human Alpha-lactalbumin Made Lethal to Tumours) was discovered during studies on the properties of human milk, and is a class of protein-lipid complexes having broad spectrum anti-cancer, and some specific anti-bacterial properties. The structure of HAMLET-like compounds consists of an aggregation of partially unfolded protein making up the majority of the compound's mass, with fatty acid molecules bound in the hydrophobic core. This is a novel protein-lipid structure and has only recently been derived by small-angle X-ray scattering analysis. The structure is the basis of a novel cytotoxicity mechanism responsible for anti-cancer activity to all of the around 50 different cancer cell types for which the HAMLET family has been trialled. Multiple cytotoxic mechanisms have been hypothesised for the HAMLET-like compounds, but it is not yet clear which of those are the initiating cytotoxic mechanism(s) and which are subsequent activities triggered by the initiating mechanism(s). In addition to the studies into the structure of these compounds, this review presents the state of knowledge of the anti-cancer aspects of HAMLET-like compounds, the HAMLET-induced cytotoxic activities to cancer and non-cancer cells, and the several prospective cell membrane and intracellular targets of the HAMLET family. The emerging picture is that HAMLET-like compounds initiate their cytotoxic effects on what may be a cancer-specific target in the cell membrane that has yet to be identified. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

  13. Of Chains and Rings: Synthetic Strategies and Theoretical Investigations for Tuning the Structure of Silver Coordination Compounds and Their Applications

    Directory of Open Access Journals (Sweden)

    Tünde Vig Slenters

    2010-05-01

    Full Text Available Varying the polyethyleneglycol spacer between two (iso-nicotinic groups of the ligand systems, a large structural variety of silver coordination compounds was obtained, starting with zero-dimensional ring systems, via one-dimensional chains, helices and double-helices to two-dimensional polycatenanes. Theoretical calculations help to understand their formation and allow predictions in some cases. These structures can be tuned by careful design of the ligand, the use of solvent and the counter ions, influencing also other important properties such as light stability and solubility. The latter is important in the context of biomedical applications, using silver compounds as antimicrobial agents.

  14. Electronic structure and optical properties of the HoCoSi and ErNiSi compounds

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, Yu. V.; Lukoyanov, A. V., E-mail: lukoyanov@imp.uran.ru; Kuz’min, Yu. I. [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Gupta, S.; Suresh, K. G. [Indian Institute of Technology, Department of Physics (India)

    2016-10-15

    The electronic structure and the optical properties of the HoCoSi and ErNiSi compounds are studied. Spin-polarized band calculations are performed in the local electron density approximation corrected for the strong electron–electron interactions in the 4f shell of a rare-earth ion (LSDA + U method [11]). The optical constants are measured by ellipsometry in a wide wavelength range, and the frequency dependences of a number of spectral parameters are determined. The calculated densities of states are used to interpret the structural features of the interband optical conductivities of the intermetallic compounds.

  15. Thermolysis preparation of ZnS nanoparticles from a nano-structure bithiazole zinc(II) coordination compound

    Science.gov (United States)

    Hosseinian, Akram; Rahimipour, Hamid Reza; Haddadi, Hedayat; Ashkarran, Ali Akbar; Mahjoub, Ali Reza

    2014-09-01

    Nano-scale and single crystals of a new tris-chelate Zn(II) compound, {[Zn(DADMBTZ)3](SCN)2ṡ4H2O}n, (1), {DADMBTZ = 2,2‧-diamino-5,5‧-dimethyl-4,4‧-bithiazole} have been synthesized by the reaction of zinc(II) sulfate, ammonium thiocyanate and DADMBTZ using sonochemical and branched tube methods, respectively. The new nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and FT-IR spectroscopy. Compound (1) was structurally characterized by single crystal X-ray diffraction. Compound (1) form a tris-chelate complex with nearly C3 symmetry. The coordination number of zinc atom in the compound is six with coordinated environments of distorted octahedral, ZnN6. In reaction with DADMBTZ, the ligand DADMBTZ acts as bidentate in compound to form five-membered chelate rings with the same internal angles in coordination polyhedron. The crystal packing is mainly stabilized by N-H- - - -N hydrogen bonding interactions. The thermal stability of compound (1) was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). ZnS nanostructures were obtained by direct thermolyses of compound (1) at 400 °C under argon atmosphere. The ZnS nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy.

  16. Effect of the partial NaCl substitution by other chloride salts on the volatile profile during the ripening of dry-cured lacón

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, R.; Munekata, P.E.; Cittadini, A.; Lorenzo, J.M.

    2016-07-01

    The influence of three salting treatments (treatment II: 50% NaCl-50% KCl; III: 45% NaCl-25% KCl-20% CaCl2-10% MgCl2; IV: 30% NaCl-50% KCl-15% CaCl2-5% MgCl2) on the formation of volatile compounds throughout the process was studied and compared to those of a control “lacón” (treatment I: 100% NaCl). There was an intense formation of volatile compounds throughout the processing, particularly during the dry-ripening stage. The most abundant chemical family in all the formulations, in the final product was hydrocarbons followed by aldehydes. The total volatile compound release was more intense in the control “lacóns” (1164 AU×106 ·g–1dry matter) than in “lacóns” from formulations II, III and IV (817–891 AU×106 ·g−1dry matter). The “lacóns” from formulation I showed the highest amounts of aldehydes. The “lacóns” from formulations I and II presented the highest amounts of hydrocarbons. The main conclusion is that the replacement of NaCl produces changes in the volatile profile and could be affect the aroma of “lacón”. (Author)

  17. Topological phase, structural, electronic, thermodynamic and optical properties of XPtSb (X=Lu, Sc) compounds

    Science.gov (United States)

    Narimani, Mitra; Nourbakhsh, Zahra

    2017-03-01

    The electronic, thermodynamic and optical properties of XPtSb (X=Lu, Sc) half Heusler compounds are studied based on density functional theory. The calculations are carried out in the presence of spin orbit interaction. The exchange correlation part of total energy is calculated within local density approximation, generalized gradient approximation, Engel-Vosco generalized gradient approximation and modified Becke and Johnson exchange potential with the correlation potential of the generalized gradient approximation. The effect of pressure on the electron density of states and linear coefficient of the electronic specific heat is studied. Using the band structure calculations at different pressures, the band inversion strength and topological phase transition of these compounds are investigated. Some thermodynamic properties of XPtSb compounds by different thermal models using the non-equilibrium Gibbs function are studied and compared with experiment. Furthermore the effect of pressure on dielectric function of XPtSb (X=Lu, Sc) compounds is investigated.

  18. Structure-based interpretation of biotransformation pathways of amide-containing compounds in sludge-seeded bioreactors.

    Science.gov (United States)

    Helbling, Damian E; Hollender, Juliane; Kohler, Hans-Peter E; Fenner, Kathrin

    2010-09-01

    Partial microbial degradation of xenobiotic compounds in wastewater treatment plants (WWTPs) results in the formation of transformation products, which have been shown to be released and detectable in surface waters. Rule-based systems to predict the structures of microbial transformation products often fail to discriminate between alternate transformation pathways because structural influences on enzyme-catalyzed reactions in complex environmental systems are not well understood. The amide functional group is one such common substructure of xenobiotic compounds that may be transformed through alternate transformation pathways. The objective of this work was to generate a self-consistent set of biotransformation data for amide-containing compounds and to develop a metabolic logic that describes the preferred biotransformation pathways of these compounds as a function of structural and electronic descriptors. We generated transformation products of 30 amide-containing compounds in sludge-seeded bioreactors and identified them by means of HPLC-linear ion trap-orbitrap mass spectrometry. Observed biotransformation reactions included amide hydrolysis and N-dealkylation, hydroxylation, oxidation, ester hydrolysis, dehalogenation, nitro reduction, and glutathione conjugation. Structure-based interpretation of the results allowed for identification of preferences in biotransformation pathways of amides: primary amides hydrolyzed rapidly; secondary amides hydrolyzed at rates influenced by steric effects; tertiary amides were N-dealkylated unless specific structural moieties were present that supported other more readily enzyme-catalyzed reactions. The results allowed for the derivation of a metabolic logic that could be used to refine rule-based biotransformation pathway prediction systems to more specifically predict biotransformations of amide-containing compounds.

  19. Enzymes useful for chiral compound synthesis: structural biology, directed evolution, and protein engineering for industrial use.

    Science.gov (United States)

    Kataoka, Michihiko; Miyakawa, Takuya; Shimizu, Sakayu; Tanokura, Masaru

    2016-07-01

    Biocatalysts (enzymes) have many advantages as catalysts for the production of useful compounds as compared to chemical catalysts. The stereoselectivity of the enzymes is one advantage, and thus the stereoselective production of chiral compounds using enzymes is a promising approach. Importantly, industrial application of the enzymes for chiral compound production requires the discovery of a novel useful enzyme or enzyme function; furthermore, improving the enzyme properties through protein engineering and directed evolution approaches is significant. In this review, the significance of several enzymes showing stereoselectivity (quinuclidinone reductase, aminoalcohol dehydrogenase, old yellow enzyme, and threonine aldolase) in chiral compound production is described, and the improvement of these enzymes using protein engineering and directed evolution approaches for further usability is discussed. Currently, enzymes are widely used as catalysts for the production of chiral compounds; however, for further use of enzymes in chiral compound production, improvement of enzymes should be more essential, as well as discovery of novel enzymes and enzyme functions.

  20. Structure and Biological Activities of Novel Triazole Compounds Containing 1,3,4-Oxadiazole Ring

    Institute of Scientific and Technical Information of China (English)

    XU Liang-zhong; BI Wen-zhao; SHANG Yu-qing; ZHAI Zhi-wei; YI Xu

    2008-01-01

    Eighteen novel triazole compounds containing 1,3,4-oxadiazole groups were synthesized from 2-(1H-1,2,4-triazol-1-y1)acetohydrazide and carbon disulfide by several step reactions. The target compounds were characterized by elemental analysis, 1H NMR, 13C NMR, IR, MS, and X-ray crystallography. The results of preliminary biological tests show that all the compounds exhibit certain fungicidal activities.

  1. Correlation between the structure and biological activity studies of supramolecular coordination azodye compounds

    Directory of Open Access Journals (Sweden)

    M.I. Abou-Dobara

    2017-02-01

    Full Text Available A series of novel bidentate azodye quinoline ligands were synthesized with various p-aromatic amines like p-(OCH3, CH3, H, Cl and NO2. Novel azodye (HLn and complexes [Cu(II/Ni(II] of these ligands have been characterized on the basis of elemental analysis, molar conductance and magnetic measurements, infrared and electronic spectral studies. Suitable structures have been proposed for these complexes. The synthesized ligands and their metal complexes were screened for their antimicrobial activity against four local bacterial species, two Gram positive bacteria (Bacillus cereus and Staphylococcus aureus and two Gram negative bacteria (Escherichia coli and Klebsiella pneumoniae as well as against four local fungal species; namely Aspergillus niger, Alternaria alternata, Penicillium italicum and Fusarium oxysporium. The tested compounds have good antibacterial activity against B. cereus, E. coli and K. pneumoniae. Very low effect was detected against S. aureus and F. oxysporium. We found that the results of antifungal activity of HLn revealed that the complexes are more toxic than ligands against fungi due to the transition metal involved in the coordination. Also Cu2+ complexes are more active than Ni2+ complexes against B. cereus, E. coli and K. pneumoniae. The size of the clear zone was in the following order p-(OCH3 < CH3 < H < Cl < NO2 as expected from Hammett’s constants σR.

  2. A Study on Magnetic Decoupling of Compound-Structure Permanent-Magnet Motor for HEVs Application

    Directory of Open Access Journals (Sweden)

    Qiwei Xu

    2016-10-01

    Full Text Available The compound-structure permanent-magnet (CSPM motor is used for an electrical continuously-variable transmission (E-CVT in a hybrid electric vehicle (HEV. It can make the internal combustion engine (ICE independent of the road loads and run in the high efficiency area to improve the fuel economy and reduce the emissions. This paper studies the magnetic coupling of a new type of CSPM motor used in HEVs. Firstly, through the analysis of the parameter matching with CSPM in the HEV, we receive the same dynamic properties’ design parameters between the CSPM motor and the THS (Toyota Hybrid System of the Toyota Prius. Next, we establish the equivalent magnetic circuit model of the overall and the secondary model considering the tangential and radial flux distribution in the outer rotor of the CSPM motor. Based on these two models, we explore the internal magnetic coupling rule of the CSPM motor. Finally, finite element method analysis in 2D-ansoft is used to analyze the magnetic field distribution of the CSPM motor in different operation modes. By the result of the finite element method analysis, the internal magnetic decoupling scheme is put forward, laying the theoretical foundation for the further application of the CSPM motor in HEVs.

  3. Multivariate analysis of chromatographic retention data as a supplementary means for grouping structurally related compounds.

    Science.gov (United States)

    Fasoula, S; Zisi, Ch; Sampsonidis, I; Virgiliou, Ch; Theodoridis, G; Gika, H; Nikitas, P; Pappa-Louisi, A

    2015-03-27

    In the present study a series of 45 metabolite standards belonging to four chemically similar metabolite classes (sugars, amino acids, nucleosides and nucleobases, and amines) was subjected to LC analysis on three HILIC columns under 21 different gradient conditions with the aim to explore whether the retention properties of these analytes are determined from the chemical group they belong. Two multivariate techniques, principal component analysis (PCA) and discriminant analysis (DA), were used for statistical evaluation of the chromatographic data and extraction similarities between chemically related compounds. The total variance explained by the first two principal components of PCA was found to be about 98%, whereas both statistical analyses indicated that all analytes are successfully grouped in four clusters of chemical structure based on the retention obtained in four or at least three chromatographic runs, which, however should be performed on two different HILIC columns. Moreover, leave-one-out cross-validation of the above retention data set showed that the chemical group in which an analyte belongs can be 95.6% correctly predicted when the analyte is subjected to LC analysis under the same four or three experimental conditions as the all set of analytes was run beforehand. That, in turn, may assist with disambiguation of analyte identification in complex biological extracts.

  4. Synthesis and structures of two cobalt compounds of 2-amino-2-methyl-1-propanol

    Indian Academy of Sciences (India)

    YONGJIE QIN; SHANSHAN YANG; LONG LIU; YUNING LIANG; ZILU CHEN

    2017-01-01

    The reactions of 2-amino-2-methyl-1-propanol (MepH) with Co(ClO₄) ₂•6H₂O in the presence of acetic acid gave [Co₂ (Mep) ₃ (OAc)(MepH)](ClO₄) ₂•MepH (1) and [CoIII ₄ CoII ₂ (Mep)8(μ₃-OH) ₂ (OAc) ₄](ClO₄) ₂• 2EtOH•2H₂O (2). They were characterized by elemental analysis, IR and single crystal X-ray diffraction analysis. Compound 1 presents a dinuclear structure with its two Co atoms linked by two Mep⁻ ligands and one acetate ligand. The two Co(II) and four Co(III) centers in 2 are held together by eight Mep⁻ ligands, two μ₃-OH⁻ ions and four acetate ligands to form a hexanuclear skeleton which contains a defected face-shared dicubane core. Their discrete polynuclear units are further linked into double-layered and mono-layered two-dimensional H-bonded framework, respectively.

  5. CORAL: quantitative structure-activity relationship models for estimating toxicity of organic compounds in rats.

    Science.gov (United States)

    Toropova, A P; Toropov, A A; Benfenati, E; Gini, G; Leszczynska, D; Leszczynski, J

    2011-09-01

    For six random splits, one-variable models of rat toxicity (minus decimal logarithm of the 50% lethal dose [pLD50], oral exposure) have been calculated with CORAL software (http://www.insilico.eu/coral/). The total number of considered compounds is 689. New additional global attributes of the simplified molecular input line entry system (SMILES) have been examined for improvement of the optimal SMILES-based descriptors. These global SMILES attributes are representing the presence of some chemical elements and different kinds of chemical bonds (double, triple, and stereochemical). The "classic" scheme of building up quantitative structure-property/activity relationships and the balance of correlations (BC) with the ideal slopes were compared. For all six random splits, best prediction takes place if the aforementioned BC along with the global SMILES attributes are included in the modeling process. The average statistical characteristics for the external test set are the following: n = 119 ± 6.4, R(2) = 0.7371 ± 0.013, and root mean square error = 0.360 ± 0.037. Copyright © 2011 Wiley Periodicals, Inc.

  6. Electronic magnetic structure of intermetallic compounds RNi2Mn studied by XMCD

    Science.gov (United States)

    Kuznetsova, Tatyana V.; Grebennikov, Vladimir I.; Gerasimov, E. G.; Mushnikov, N. V.

    2017-10-01

    The x-ray absorption near edge structure (XANES) and the x-ray magnetic circular dichroism (XMCD) measurements in the hard X-ray range at the Ni and Mn K edges and Tb, Dy L2, 3 edges were carried out in TbNi2Mn and DyNi2Mn in magnetic field up to 6 T at 10 K. XMCD on the Dy and Tb L-edges reaches 3.2%. The spin and orbital d-projected density of states on Tb and Dy atoms were obtained from the XMCD spectra. The Ni and Mn K-edges absorptions are practically identical in both compounds, as well as the dichroism spectra. The magnitude of dichroism is less than 0.5% and its length of about 50 eV. Scattering of outgoing p-wave on magnetic atoms environment is the main source of the K-edge dichroism. Element-specific magnetic hysteresis-loops measurements on TbNi2Mn and DyNi2Mn were performed by X-ray magnetic circular dichroism.

  7. 15N NMR study of nitrate ion structure and dynamics in hydrotalcite-like compounds

    Science.gov (United States)

    Hou, X.; James, Kirkpatrick R.; Yu, P.; Moore, D.; Kim, Y.

    2000-01-01

    We report here the first nuclear magnetic resonance (NMR) spectroscopic study of the dynamical and structural behavior of nitrate on the surface and in the interlayer of hydrotalcite-like compounds (15NO3--HT). Spectroscopically resolvable surface-absorbed and interlayer NO3- have dramatically different dynamical characteristics. The interlayer nitrate shows a well defined, temperature independent uniaxial chemical shift anisotropy (CS A) powder pattern. It is rigidly held or perhaps undergoes rotation about its threefold axis at all temperatures between -100 ??C and +80 ??C and relative humidities (R.H.) from 0 to 100% at room temperature. For surface nitrate, however, the dynamical behavior depends substantially on temperature and relative humidity. Analysis of the temperature and R.H. dependences of the peak width yields reorieritational frequencies which increase from essentially 0 at -100 ??C to 2.6 ?? 105 Hz at 60 ??C and an activation energy of 12.6 kJ/mol. For example, for samples at R.H. = 33%, the surface nitrate is isotropically mobile at frequencies greater than 105 Hz at room temperature, but it becomes rigid or only rotates on its threefold axis at -100 ??C. For dry samples and samples heated at 200 ??C (R.H. near 0%), the surface nitrate is not isotropically averaged at room temperature. In contrast to our previous results for 35Cl--containing hydrotalcite (35Cl--HT), no NMR detectable structural phase transition is observed for 15NO3--HT. The mobility of interlayer nitrate in HT is intermediate between that of carbonate and chloride.

  8. Exploration of stable compounds, crystal structures, and superconductivity in the Be-H system

    Directory of Open Access Journals (Sweden)

    Shuyin Yu

    2014-10-01

    Full Text Available Using first-principles variable-composition evolutionary methodology, we explored the high-pressure structures of beryllium hydrides between 0 and 400 GPa. We found that BeH2 remains the only stable compound in this pressure range. The pressure-induced transformations are predicted as I b a m → P 3 ̄ m 1 → R 3 ̄ m → C m c m → P 4 / n m m , which occur at 24, 139, 204 and 349 GPa, respectively. P 3 ̄ m 1 and R 3 ̄ m structures are layered polytypes based on close packings of H atoms with Be atoms filling all octahedral voids in alternating layers. Cmcm and P4/nmm contain two-dimensional triangular networks with each layer forming a kinked slab in the ab-plane. P 3 ̄ m 1 and R 3 ̄ m are semiconductors while Cmcm and P4/nmm are metallic. We have explored superconductivity of both metal phases, and found large electron-phonon coupling parameters of λ = 0.63 for Cmcm with a Tc of 32.1-44.1 K at 250 GPa and λ = 0.65 for P4/nmm with a Tc of 46.1-62.4 K at 400 GPa. The dependence of Tc on pressure indicates that Tc initially increases to a maximum of 45.1 K for Cmcm at 275 GPa and 97.0 K for P4/nmm at 365 GPa, and then decreases with increasing pressure for both phases.

  9. Structural basis for the enhanced stability of protein model compounds and peptide backbone unit in ammonium ionic liquids.

    Science.gov (United States)

    Vasantha, T; Attri, Pankaj; Venkatesu, Pannuru; Devi, R S Rama

    2012-10-04

    Protein folding/unfolding is a fascinating study in the presence of cosolvents, which protect/disrupt the native structure of protein, respectively. The structure and stability of proteins and their functional groups may be modulated by the addition of cosolvents. Ionic liquids (ILs) are finding a vast array of applications as novel cosolvents for a wide variety of biochemical processes that include protein folding. Here, the systematic and quantitative apparent transfer free energies (ΔG'(tr)) of protein model compounds from water to ILs through solubility measurements as a function of IL concentration at 25 °C have been exploited to quantify and interpret biomolecular interactions between model compounds of glycine peptides (GPs) with ammonium based ILs. The investigated aqueous systems consist of zwitterionic glycine peptides: glycine (Gly), diglycine (Gly(2)), triglycine (Gly(3)), tetraglycine (Gly(4)), and cyclic glycylglycine (c(GG)) in the presence of six ILs such as diethylammonium acetate (DEAA), diethylammonium hydrogen sulfate (DEAS), triethylammonium acetate (TEAA), triethylammonium hydrogen sulfate (TEAS), triethylammonium dihydrogen phosphate (TEAP), and trimethylammonium acetate (TMAA). We have observed positive values of ΔG'(tr) for GPs from water to ILs, indicating that interactions between ILs and GPs are unfavorable, which leads to stabilization of the structure of model protein compounds. Moreover, our experimental data ΔG'(tr) is used to obtain transfer free energies (Δg'(tr)) of the peptide backbone unit (or glycyl unit) (-CH(2)C═ONH-), which is the most numerous group in globular proteins, from water to IL solutions. To obtain the mechanism events of the ILs' role in enhancing the stability of the model compounds, we have further obtained m-values for GPs from solubility limits. These results explicitly elucidate that all alkyl ammonium ILs act as stabilizers for model compounds through the exclusion of ILs from model compounds of

  10. Swelling/deswelling of polyacrylamide gels in aqueous NaCl solution: Light scattering and macroscopic swelling study

    Indian Academy of Sciences (India)

    M Sivanantham; B V R Tata

    2012-09-01

    Swelling kinetics of water-swollen polyacrylamide (PAAm) hydrogels (WSG) was investigated in various concentrations of aqueous NaCl by macroscopic swelling measurements. For lower concentration of NaCl, WSG showed exponential swelling whereas at higher concentration of NaCl it underwent deswelling at short times and exponential swelling at long times. From these studies, collective diffusion coefficient, , of the polymer network and polymer–solvent interaction parameter, , were calculated and found to decrease with increase in [NaCl]. Collective diffusion coefficients measured from dynamic light scattering (DLS) and that obtained from macroscopic swelling measurements are found to agree well. Measured ensemble-averaged dynamic structure factor (, ) for WSG and salt-swollen gels (SSG) showed an initial decay followed by a plateau at long times and it can be described by harmonically bound Brownian particle (HBBP) model. Enhanced scattering intensity at low scattering angles using static light scattering (SLS) measurements revealed the presence of inhomogeneities in PAAm gels. The reasons for increased scattering intensity of SSG over WSG gel and the linear decrease of with increase in NaCl concentration are explained.

  11. Structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds

    Science.gov (United States)

    Liu, Yangzhen; Xing, Jiandong; Fu, Hanguang; Li, Yefei; Sun, Liang; Lv, Zheng

    2017-08-01

    The properties of sulfides are important in the design of new iron-steel materials. In this study, first-principles calculations were used to estimate the structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds. The results reveal that these XS binary compounds are thermodynamically stable, because their formation enthalpy is negative. The elastic constants, Cij, and moduli (B, G, E) were investigated using stress-strain and Voigt-Reuss-Hill approximation, respectively. The sulfide anisotropy was discussed from an anisotropic index and three-dimensional surface contours. The electronic structures reveal that the bonding characteristics of the XS compounds are a mixture of metallic and covalent bonds. Using a quasi-harmonic Debye approximation, the heat capacity at constant pressure and constant volume was estimated. NiS possesses the largest CP and CV of the sulfides.

  12. Effects of Ga substitution on the structural and magnetic properties of half metallic Fe2MnSi Heusler compound

    Science.gov (United States)

    Pedro, S. S.; Caraballo Vivas, R. J.; Andrade, V. M.; Cruz, C.; Paixão, L. S.; Contreras, C.; Costa-Soares, T.; Caldeira, L.; Coelho, A. A.; Carvalho, A. Magnus G.; Rocco, D. L.; Reis, M. S.

    2015-01-01

    The so-called half-metallic magnets have been proposed as good candidates for spintronic applications due to the feature of exhibiting a hundred percent spin polarization at the Fermi level. Such materials follow the Slater-Pauling rule, which relates the magnetic moment with the valence electrons in the system. In this paper, we study the bulk polycrystalline half-metallic Fe2MnSi Heusler compound replacing Si by Ga to determine how the Ga addition changes the magnetic, the structural, and the half-metal properties of this compound. The material does not follow the Slater-Pauling rule, probably due to a minor structural disorder degree in the system, but a linear dependence on the magnetic transition temperature with the valence electron number points to the half-metallic behavior of this compound.

  13. Structural, electronic and elastic properties of REIr{sub 2} (RE=La and Ce) Laves phase compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Deepika, E-mail: deepika89shrivastava@gmail.com; Fatima, Bushra; Sanyal, Sankar P. [Department of Physics, Barkatullah University, Bhopal, 462026 (India)

    2016-05-23

    REIr{sub 2} (RE = La and Ce) Laves phase intermetallic compounds were investigated with respect to their structural, electronic and elastic properties using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) as implemented in WIEN2k code. The ground state properties such as lattice constants (a{sub 0}), bulk modulus (B), pressure derivative of bulk modulus (B′) and density of state at Fermi level N(E{sub F}) have been obtained by optimization method. The electronic structure (BS, TDOS and PDOS) reveals that these Laves phase compounds are metallic in nature. The calculated elastic constants indicate that these compounds are mechanically stable at ambient pressure and found to be ductile in nature.

  14. Electronic and magnetic properties of Cr-Mn-Ni-Al compound with LiMgPdSb-type structure

    Science.gov (United States)

    Wang, L. Y.; Wang, X. T.; Guo, R. K.; Lin, T. T.; Liu, G. D.

    2016-10-01

    We investigate the electronic and magnetic properties of Cr-Mn-Ni-Al compound with a LiMgPdSn-type structure in three different atomic arrangement configurations (AAC) by using the first-principles calculations. It was found that Cr-Mn-Ni-Al compound with type I AAC exhibits a spin-gapless semiconductive characteristic. The type II AAC is the most stable one and exhibits an especial band structure where the Fermi level slightly crosses the top of the valence bands in spin-up channel and the bottom of conductive bands in spin-down channel, which leads to the electronic transport with the spin-resolved carrier type. The Cr-Mn-Ni-Al compound shows an ordinary metallic behavior in type III AAC. The three nonequivalent atomic arrangement configurations of Cr-Mn-Ni-Al are all in ferromagnetic ground state under their equilibrium lattice parameters.

  15. Tolerance of soil flagellates to increased NaCl levels

    DEFF Research Database (Denmark)

    Ekelund, Flemming

    2002-01-01

    on a freshwater medium from a non-exposed soil were unable to thrive at salinities above 15 ppt, and showed reduced growth rates even at low salt salinities (1-5 ppt). The findings suggest that heterotrophic soil flagellates are less tolerant to NaCl than their aquatic relatives, possibly due to their long...

  16. Melting of sodium clusters in electron irradiated NaCl

    NARCIS (Netherlands)

    Sugonyako, AV; Vainshtein, DI; Turkin, AA; den Hartog, HW; Bukharaev, AA

    2004-01-01

    In this paper we present the results of the first systematic investigation of the geometrical properties of sodium nanoclusters in NaCl using the combined results of differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The melting behaviour of the sodium nanoclusters which had

  17. Acrylamide Mitigation in Potato Chips by Using NaCl

    DEFF Research Database (Denmark)

    Pedreschi, Franco; Granby, Kit; Risum, Jørgen

    2010-01-01

    slices in a NaCl solution over the acrylamide formation in the resultant potato chips. Potato slices (Verdi variety, diameter 40 mm, width 2.0 mm) were fried at 170 °C for 5 min (final moisture content of ∼2.0%). Prior to frying, the potato slices were treated in one of the following ways: (1) control...

  18. Nano-sized precipitated formations in irradiated NaCl

    NARCIS (Netherlands)

    Sugonyako, Anton V.

    2007-01-01

    The interest in the formation of radiation damage in alkali halides and in particular, in NaCl, is stimulated by the fact that rock-salt in stable geological formations is a prominent candidate medium for storage of high-level waste (HLW) of nuclear power plants. Since the 1950s, scientists and engi

  19. Analysis of the structural, electronic and optic properties of Ni doped MgSiP2 semiconductor chalcopyrite compound

    Science.gov (United States)

    Kocak, Belgin; Ciftci, Yasemin Oztekin

    2016-03-01

    The structural, electronic band structure and optic properties of the Ni doped MgSiP2 chalcopyrite compound have been performed by using first-principles method in the density functional theory (DFT) as implemented in Vienna Ab-initio Simulation Package (VASP). The generalized gradient approximation (GGA) in the scheme of Perdew, Burke and Ernzerhof (PBE) is used for the exchange and correlation functional. The present lattice constant (a) follows generally the Vegard's law. The electronic band structure, total and partial density of states (DOS and PDOS) are calculated. We present data for the frequency dependence of imaginary and real parts of dielectric functions of Ni doped MgSiP2. For further investigation of the optical properties the reflectivity, refractive index, extinction coefficient and electron energy loss function are also predicted. Our obtained results indicate that the lattice constants, electronic band structure and optical properties of this compound are dependent on the substitution concentration of Ni.

  20. The cytotoxicity of organobismuth compounds with certain molecular structures can be diminished by replacing the bismuth atom with an antimony atom in the molecules.

    Science.gov (United States)

    Kohri, Kumiko; Yoshida, Eiko; Yasuike, Shuji; Fujie, Tomoya; Yamamoto, Chika; Kaji, Toshiyuki

    2015-06-01

    Organic-inorganic hybrid molecules, which are composed of an organic structure and metal(s), are indispensable for synthetic chemical reactions; however, their toxicity has been incompletely understood. In the present study, we discovered two cytotoxic organobismuth compounds whose cytotoxicity diminished upon replacement of the intramolecular bismuth atom with an antimony atom. The intracellular accumulation of the organobismuth compounds was much higher than that of the organoantimony compounds with the corresponding organic structures. We also showed that both the organic structure and bismuth atom are required for certain organobismuth compounds to exert their cytotoxic effect, suggesting that the cytotoxicity of such a compound is a result of an interaction between the organic structure and the bismuth atom. The present data suggest that organobismuth compounds with certain molecular structures exhibit cytotoxicity via an interaction between the molecular structure and the bismuth atom, and this cytotoxicity can be diminished by replacing the bismuth atom with an antimony atom, resulting in lower intracellular accumulation.

  1. The structure-activity relationship of fire retardant phosphorus compounds in wood

    NARCIS (Netherlands)

    Stevens, R.S.A.; Es, van D.S.; Bezemer, R.C.; Kranenbarg, A.

    2006-01-01

    Sawdust of Scots Pine sapwood was chemically modified with various alkyl- and phenylchlorophosphorus compounds. The formation of covalent bonds was confirmed with solid state CP-MAS 13C NMR. According to thermogravimetric analysis (TGA), all phosphorus compounds decreased the temperature for the max

  2. A review on how Lanthanide impurity levels change with chemistry and structure of inorganic compounds

    NARCIS (Netherlands)

    Dorenbos, P.

    2012-01-01

    The energy of the 4f-5d transitions of divalent and trivalent lanthanide impurities in compounds depends strongly on the type of lanthanide, its valence, and the type of compound. Despite this large variability there is much systematic in 4f-5d transition energy. Once it is known for one lanthanide

  3. Synthesis of two-dimensional TlxBi1−x compounds and Archimedean encoding of their atomic structure

    Science.gov (United States)

    Gruznev, Dimitry V.; Bondarenko, Leonid V.; Matetskiy, Andrey V.; Mihalyuk, Alexey N.; Tupchaya, Alexandra Y.; Utas, Oleg A.; Eremeev, Sergey V.; Hsing, Cheng-Rong; Chou, Jyh-Pin; Wei, Ching-Ming; Zotov, Andrey V.; Saranin, Alexander A.

    2016-01-01

    Crystalline atomic layers on solid surfaces are composed of a single building block, unit cell, that is copied and stacked together to form the entire two-dimensional crystal structure. However, it appears that this is not an unique possibility. We report here on synthesis and characterization of the one-atomic-layer-thick TlxBi1−x compounds which display quite a different arrangement. It represents a quasi-periodic tiling structures that are built by a set of tiling elements as building blocks. Though the layer is lacking strict periodicity, it shows up as an ideally-packed tiling of basic elements without any skips or halting. The two-dimensional TlxBi1−x compounds were formed by depositing Bi onto the Tl-covered Si(111) surface where Bi atoms substitute appropriate amount of Tl atoms. Atomic structure of each tiling element as well as arrangement of TlxBi1−x compounds were established in a detail. Electronic properties and spin texture of the selected compounds having periodic structures were characterized. The shown example demonstrates possibility for the formation of the exotic low-dimensional materials via unusual growth mechanisms. PMID:26781340

  4. Synthesis of two-dimensional TlxBi1-x compounds and Archimedean encoding of their atomic structure

    Science.gov (United States)

    Gruznev, Dimitry V.; Bondarenko, Leonid V.; Matetskiy, Andrey V.; Mihalyuk, Alexey N.; Tupchaya, Alexandra Y.; Utas, Oleg A.; Eremeev, Sergey V.; Hsing, Cheng-Rong; Chou, Jyh-Pin; Wei, Ching-Ming; Zotov, Andrey V.; Saranin, Alexander A.

    2016-01-01

    Crystalline atomic layers on solid surfaces are composed of a single building block, unit cell, that is copied and stacked together to form the entire two-dimensional crystal structure. However, it appears that this is not an unique possibility. We report here on synthesis and characterization of the one-atomic-layer-thick TlxBi1-x compounds which display quite a different arrangement. It represents a quasi-periodic tiling structures that are built by a set of tiling elements as building blocks. Though the layer is lacking strict periodicity, it shows up as an ideally-packed tiling of basic elements without any skips or halting. The two-dimensional TlxBi1-x compounds were formed by depositing Bi onto the Tl-covered Si(111) surface where Bi atoms substitute appropriate amount of Tl atoms. Atomic structure of each tiling element as well as arrangement of TlxBi1-x compounds were established in a detail. Electronic properties and spin texture of the selected compounds having periodic structures were characterized. The shown example demonstrates possibility for the formation of the exotic low-dimensional materials via unusual growth mechanisms.

  5. Synthesis of two-dimensional Tl(x)Bi(1-x) compounds and Archimedean encoding of their atomic structure.

    Science.gov (United States)

    Gruznev, Dimitry V; Bondarenko, Leonid V; Matetskiy, Andrey V; Mihalyuk, Alexey N; Tupchaya, Alexandra Y; Utas, Oleg A; Eremeev, Sergey V; Hsing, Cheng-Rong; Chou, Jyh-Pin; Wei, Ching-Ming; Zotov, Andrey V; Saranin, Alexander A

    2016-01-19

    Crystalline atomic layers on solid surfaces are composed of a single building block, unit cell, that is copied and stacked together to form the entire two-dimensional crystal structure. However, it appears that this is not an unique possibility. We report here on synthesis and characterization of the one-atomic-layer-thick Tl(x)Bi(1-x) compounds which display quite a different arrangement. It represents a quasi-periodic tiling structures that are built by a set of tiling elements as building blocks. Though the layer is lacking strict periodicity, it shows up as an ideally-packed tiling of basic elements without any skips or halting. The two-dimensional Tl(x)Bi(1-x) compounds were formed by depositing Bi onto the Tl-covered Si(111) surface where Bi atoms substitute appropriate amount of Tl atoms. Atomic structure of each tiling element as well as arrangement of Tl(x)Bi(1-x) compounds were established in a detail. Electronic properties and spin texture of the selected compounds having periodic structures were characterized. The shown example demonstrates possibility for the formation of the exotic low-dimensional materials via unusual growth mechanisms.

  6. (3+2)-Dimensional superspace approach to the structure of the incommensurate intergrowth compound - (sbs)(1.15)tis2

    NARCIS (Netherlands)

    Ren, Y; Meetsma, A.; Petricek, V.; van Smaalen, Sander; Wiegers, G.A

    1995-01-01

    The inorganic misfit-layer compound (SbS)(1.15)TiS2 was prepared by high-temperature reaction of the elements. The structure, determined by single-crystal X-ray diffraction, is described by two interpenetrating incommensurately modulated subsystems. The first subsystem comprises TiS2 sandwiches, wit

  7. The crystal structure and phase transitions of the magnetic shape memory compound Ni{sub 2}MnGa

    Energy Technology Data Exchange (ETDEWEB)

    Brown, P J [Physics Department, Loughborough University, Leicestershire (United Kingdom); Crangle, J [Department of Physics, University of Sheffield, Sheffield (United Kingdom); Kanomata, T [Faculty of Engineering, Tohuku Gakuin University, Tadajo 985-8537 (Japan); Matsumoto, M [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577 (Japan); Neumann, K-U [Physics Department, Loughborough University, Leicestershire (United Kingdom); Ouladdiaf, B [Institut Laue-Langevin, BP 156, 38042 Grenoble (France); Ziebeck, K R A [Physics Department, Loughborough University, Leicestershire (United Kingdom)

    2002-11-04

    High resolution neutron powder diffraction and single crystal measurements on the ferromagnetic shape memory compound Ni{sub 2}MnGa have been carried out. They enabled the sequence of transformations which take place when the unstressed, stoichiometric compound is cooled from 400 to 20 K to be established. For the first time the crystallographic structure of each of the phases which occur has been determined. At 400 K the compound has the cubic L2{sub 1} structure, and orders ferromagnetically at T{sub C} {approx} 365 K. On cooling below {approx} 260 K a super-structure, characterized by tripling of the repeat in one of the (110){sub cubic} directions, forms. This phase, known as the pre-martensitic phase, persists down to the structural phase transition at T{sub M} {approx} 200 K and can be described by an orthorhombic unit cell with lattice parameters a{sub ortho} = 1/{radical}2a{sub cubic}, b{sub ortho} = 3/{radical}2a{sub cubic}, c{sub ortho} = a{sub cubic} and space group Pnnm. Below T{sub M} the compound has a related orthorhombic super-cell with b{sub ortho} {approx} 7/{radical}2a{sub cubic}, which can be described within the same space group. The new modulation appears abruptly at T{sub M} and remains stable down to at least 20 K.

  8. The crystal structure and phase transitions of the magnetic shape memory compound Ni2MnGa

    Science.gov (United States)

    Brown, P. J.; Crangle, J.; Kanomata, T.; Matsumoto, M.; Neumann, K.-U.; Ouladdiaf, B.; Ziebeck, K. R. A.

    2002-11-01

    High resolution neutron powder diffraction and single crystal measurements on the ferromagnetic shape memory compound Ni2MnGa have been carried out. They enabled the sequence of transformations which take place when the unstressed, stoichiometric compound is cooled from 400 to 20 K to be established. For the first time the crystallographic structure of each of the phases which occur has been determined. At 400 K the compound has the cubic L21 structure, and orders ferromagnetically at TC ≈ 365 K. On cooling below ~ 260 K a super-structure, characterized by tripling of the repeat in one of the cubic directions, forms. This phase, known as the pre-martensitic phase, persists down to the structural phase transition at TM ≈ 200 K and can be described by an orthorhombic unit cell with lattice parameters aortho = 1/√2acubic, bortho = 3/√2acubic, cortho = acubic and space group Pnnm. Below TM the compound has a related orthorhombic super-cell with bortho ≈ 7/√2acubic, which can be described within the same space group. The new modulation appears abruptly at TM and remains stable down to at least 20 K.

  9. Neutron Powder Diffraction Study on Structure of LaNi3.8AlMn0.2 Compound

    Institute of Scientific and Technical Information of China (English)

    HAN; Wen-ze; GUO; Hao; SUN; Kai; CHEN; De-min; LIU; Shi; WU; Er-dong; LIU; Yun-tao; CHEN; Dong-feng

    2015-01-01

    The structures of original LaNi3.8AlMn0.2alloy and subsequent compounds by means of annealing at different temperatures(850,900,950,1 000℃)were examined by using neutron diffraction and X-ray diffraction,as shown in Figure 1.Based on the Rietveld method,the diffraction

  10. Overcoming Chloroquine Resistance in Malaria: Design, Synthesis, and Structure-Activity Relationships of Novel Hybrid Compounds.

    Science.gov (United States)

    Boudhar, Aicha; Ng, Xiao Wei; Loh, Chiew Yee; Chia, Wan Ni; Tan, Zhi Ming; Nosten, Francois; Dymock, Brian W; Tan, Kevin S W

    2016-05-01

    Resistance to antimalarial therapies, including artemisinin, has emerged as a significant challenge. Reversal of acquired resistance can be achieved using agents that resensitize resistant parasites to a previously efficacious therapy. Building on our initial work describing novel chemoreversal agents (CRAs) that resensitize resistant parasites to chloroquine (CQ), we herein report new hybrid single agents as an innovative strategy in the battle against resistant malaria. Synthetically linking a CRA scaffold to chloroquine produces hybrid compounds with restored potency toward a range of resistant malaria parasites. A preferred compound, compound 35, showed broad activity and good potency against seven strains resistant to chloroquine and artemisinin. Assessment of aqueous solubility, membrane permeability, and in vitro toxicity in a hepatocyte line and a cardiomyocyte line indicates that compound 35 has a good therapeutic window and favorable drug-like properties. This study provides initial support for CQ-CRA hybrid compounds as a potential treatment for resistant malaria.

  11. Effect of Structure on the Interactions between Five Natural Antimicrobial Compounds and Phospholipids of Bacterial Cell Membrane on Model Monolayers

    Directory of Open Access Journals (Sweden)

    Stella W. Nowotarska

    2014-06-01

    Full Text Available Monolayers composed of bacterial phospholipids were used as model membranes to study interactions of the naturally occurring phenolic compounds 2,5-dihydroxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde, and the plant essential oil compounds carvacrol, cinnamaldehyde, and geraniol, previously found to be active against both Gram-positive and Gram-negative pathogenic microorganisms. The lipid monolayers consist of 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE, 1,2-dihexa- decanoyl-sn-glycero-3-phospho-(1'-rac-glycerol (DPPG, and 1,1',2,2'-tetratetradecanoyl cardiolipin (cardiolipin. Surface pressure–area (π-A and surface potential–area (Δψ-A isotherms were measured to monitor changes in the thermodynamic and physical properties of the lipid monolayers. Results of the study indicated that the five compounds modified the three lipid monolayer structures by integrating into the monolayer, forming aggregates of antimicrobial –lipid complexes, reducing the packing effectiveness of the lipids, increasing the membrane fluidity, and altering the total dipole moment in the monolayer membrane model. The interactions of the five antimicrobial compounds with bacterial phospholipids depended on both the structure of the antimicrobials and the composition of the monolayers. The observed experimental results provide insight into the mechanism of the molecular interactions between naturally-occurring antimicrobial compounds and phospholipids of the bacterial cell membrane that govern activities.

  12. Three interesting coordination compounds based on metalloligand and alkaline-earth ions: Syntheses, structures, thermal behaviors and magnetic property

    Science.gov (United States)

    Zhou, Qiang; Qian, Jun; Zhang, Chi

    2016-09-01

    Based on metalloligand LCu ([Cu(2,4-pydca)2]2-, 2,4-pydca2- = pyridine-2,4-dicarboxylate) and alkaline-earth ions (Ca2+, Sr2+, and Ba2+), three interesting coordination compounds, [Ca(H2O)7][LCu·H2O]·H2O (1), {Sr[LCu·H2O]·4H2O}n (2), and {Ba[LCu·H2O]·8H2O}n (3), have been synthesized and well-characterized by elemental analysis, infrared spectroscopy, thermogravimetric and single-crystal X-ray diffraction analysis. X-ray crystallographic studies reveal that 1 features a discrete 0D coordination compound, while 2 and 3 exhibit the 2D network and 1D chain structures, respectively. Compound 2 is constructed from {LCu}2 dimers connected with {Sr2} units, which is fabricated by two Sr2+ ions bridged via two μ2-O bridges, while compound 3 is formed by 1D {Ba}n chain linked with metalloligands LCu and exhibits an interesting sandwich like chain structure. It is noted that the coordination numbers of alkaline-earth ions are in positive correlation with their radiuses. Moreover, the magnetic property of compound 2 has been studied.

  13. Creating the New from the Old: Combinatorial Libraries Generation with Machine-Learning-Based Compound Structure Optimization.

    Science.gov (United States)

    Podlewska, Sabina; Czarnecki, Wojciech M; Kafel, Rafał; Bojarski, Andrzej J

    2017-02-15

    The growing computational abilities of various tools that are applied in the broadly understood field of computer-aided drug design have led to the extreme popularity of virtual screening in the search for new biologically active compounds. Most often, the source of such molecules consists of commercially available compound databases, but they can also be searched for within the libraries of structures generated in silico from existing ligands. Various computational combinatorial approaches are based solely on the chemical structure of compounds, using different types of substitutions for new molecules formation. In this study, the starting point for combinatorial library generation was the fingerprint referring to the optimal substructural composition in terms of the activity toward a considered target, which was obtained using a machine learning-based optimization procedure. The systematic enumeration of all possible connections between preferred substructures resulted in the formation of target-focused libraries of new potential ligands. The compounds were initially assessed by machine learning methods using a hashed fingerprint to represent molecules; the distribution of their physicochemical properties was also investigated, as well as their synthetic accessibility. The examination of various fingerprints and machine learning algorithms indicated that the Klekota-Roth fingerprint and support vector machine were an optimal combination for such experiments. This study was performed for 8 protein targets, and the obtained compound sets and their characterization are publically available at http://skandal.if-pan.krakow.pl/comb_lib/ .

  14. 2D Tl-Pb compounds on Ge(1 1 1) surface: atomic arrangement and electronic band structure.

    Science.gov (United States)

    Gruznev, D V; Bondarenko, L V; Tupchaya, A Y; Eremeev, S V; Mihalyuk, A N; Chou, J P; Wei, C M; Zotov, A V; Saranin, A A

    2017-01-25

    Structural transformations and evolution of the electron band structure in the (Tl, Pb)/Ge(1 1 1) system have been studied using low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoelectron spectroscopy and density functional theory calculations. The two 2D Tl-Pb compounds on Ge(1 1 1), [Formula: see text]-(Tl, Pb) and [Formula: see text]-(Tl, Pb), have been found and their composition, atomic arrangement and electron properties has been characterized. The (Tl, Pb)/Ge(1 1 1)[Formula: see text] compound is almost identical to the alike (Tl, Pb)/Si(1 1 1)[Formula: see text] system from the viewpoint of its atomic structure and electronic properties. They contain 1.0 ML of Tl atoms arranged into a honeycomb network of chained trimers and 1/3 ML of Pb atoms occupying the centers of the honeycomb units. The (Tl, Pb)/Ge(1 1 1)[Formula: see text] compound contains six Tl atoms and seven Pb atoms per [Formula: see text] unit cell (i.e.  ∼0.67 ML Tl and  ∼0.78 ML Pb). Its atomic structure can be visualized as consisting of Pb hexagons surrounded by Tl trimers. The (Tl, Pb)/Ge(1 1 1)[Formula: see text] and (Tl, Pb)/Ge(1 1 1)[Formula: see text] compounds are metallic and their band structures contain spin-split surface-state bands. By analogy with the (Tl, Pb)/Si(1 1 1)[Formula: see text], these (Tl, Pb)/Ge(1 1 1) compounds are believed to be promising objects for prospective studies of superconductivity in one-atom-layer systems.

  15. 2D Tl-Pb compounds on Ge(1 1 1) surface: atomic arrangement and electronic band structure

    Science.gov (United States)

    Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Eremeev, S. V.; Mihalyuk, A. N.; Chou, J. P.; Wei, C. M.; Zotov, A. V.; Saranin, A. A.

    2017-01-01

    Structural transformations and evolution of the electron band structure in the (Tl, Pb)/Ge(1 1 1) system have been studied using low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoelectron spectroscopy and density functional theory calculations. The two 2D Tl-Pb compounds on Ge(1 1 1), \\sqrt{3}× \\sqrt{3} -(Tl, Pb) and 3× 3 -(Tl, Pb), have been found and their composition, atomic arrangement and electron properties has been characterized. The (Tl, Pb)/Ge(1 1 1)\\sqrt{3}× \\sqrt{3} compound is almost identical to the alike (Tl, Pb)/Si(1 1 1)\\sqrt{3}× \\sqrt{3} system from the viewpoint of its atomic structure and electronic properties. They contain 1.0 ML of Tl atoms arranged into a honeycomb network of chained trimers and 1/3 ML of Pb atoms occupying the centers of the honeycomb units. The (Tl, Pb)/Ge(1 1 1)3× 3 compound contains six Tl atoms and seven Pb atoms per 3× 3 unit cell (i.e.  ˜0.67 ML Tl and  ˜0.78 ML Pb). Its atomic structure can be visualized as consisting of Pb hexagons surrounded by Tl trimers. The (Tl, Pb)/Ge(1 1 1)\\sqrt{3}× \\sqrt{3} and (Tl, Pb)/Ge(1 1 1)3× 3 compounds are metallic and their band structures contain spin-split surface-state bands. By analogy with the (Tl, Pb)/Si(1 1 1)\\sqrt{3}× \\sqrt{3} , these (Tl, Pb)/Ge(1 1 1) compounds are believed to be promising objects for prospective studies of superconductivity in one-atom-layer systems.

  16. Structural characterization of some Schiff base compounds: Investigation of their electrochemical, photoluminescence, thermal and anticancer activity properties

    Energy Technology Data Exchange (ETDEWEB)

    Ceyhan, Gökhan; Köse, Muhammet [Chemistry Department, Kahramanmaraş Sütcü Imam University, 46100 Kahramanmaraş (Turkey); Tümer, Mehmet, E-mail: mtumer@ksu.edu.tr [Chemistry Department, Kahramanmaraş Sütcü Imam University, 46100 Kahramanmaraş (Turkey); Demirtaş, İbrahim; Şahin Yağlioğlu, Ayse [Chemistry Department, Çankırı Karatekin University, 18100 Çankırı (Turkey); McKee, Vickie [Chemistry Department, Loughborough University, LE11 3TU Leics (United Kingdom)

    2013-11-15

    Three Schiff base compounds, N,N′-bis(2,4-dimethoxy benzaldiimine)-1,4-diamino cyclohexane (IGA{sup 1}), N,N′-bis(2,3,4-trimethoxy benzaldiimine)-1,4-diamino cyclohexane (IGA{sup 2}) and N,N′-bis(3,4,5-trimethoxy benzaldiimine)-1,4-diamino cyclohexane (IGA{sup 3}) were synthesized and characterized by the spectroscopic and analytical methods. The electrochemical and photoluminescence properties of the compounds IGA{sup 1}–IGA{sup 3} have been investigated in the different conditions. All the synthesized Schiff base compounds IGA{sup 1}, IGA{sup 2} and IGA{sup 3} were screened for their cytotoxicity (HeLa and Vera cells). The structural characterization of the Schiff base compounds was determined by single crystal X-ray diffraction studies. The molecules IGA{sup 1} and IGA{sup 3} both lie on centers of symmetry but in IGA{sup 2} the molecule has no crystallographically imposed symmetry. In the compound IGA{sup 1}, Schiff base molecules are linked by π stacking interactions. There is no evidence of π stacking in both IGA{sup 2} and IGA{sup 3}, however there are some C–H⋯π and C–H…O interactions in these compounds. The thermal stabilities of the compounds were investigated in the nitrogen atmosphere. -- Highlights: • Schiff base ligands were prepared and fully characterized. • X-ray crystal structures of Schiff base ligands were reported. • Electrochemical properties of Schiff base ligands were investigated. • Absorption and photoluminescence properties of the Schiff bases were examined.

  17. Molecular dynamics simulations of the formation for NaCl cluster at the interface between the supersaturated solution and the substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yamanaka, Shinya, E-mail: eth1503@mail4.doshisha.ac.jp; Shimosaka, Atsuko; Shirakawa, Yoshiyuki, E-mail: yshiraka@mail.doshisha.ac.jp; Hidaka, Jusuke [Doshisha University, Department of Chemical Engineering and Materials Science (Japan)

    2010-03-15

    Molecular dynamics simulations of supersaturated aqueous NaCl solution including the Pt(100) or NaCl(100) crystal surfaces have been performed at an average temperature of 298 K. The behavior of the NaCl cluster produced in the solution have been studied through the consideration of the water dielectric property near the crystalline surfaces for understanding the role of crystal growth on the surface. The surfaces in the solutions greatly influence heterogeneous nucleation in crystallization process. Density profile of the supersaturated solution and polarization of water molecules was calculated in order to describe the effect of the surfaces on the solution structure at the solid-liquid interfaces. The formation levels of NaCl clusters heavily depended on the water orientation at the interfaces. NaCl clusters were easily formed near the Pt(100) surface compared with the NaCl(100) surface owing to a different construction of water molecules between the platinum and NaCl surface.

  18. Estimation of the volume of distribution of some pharmacologically important compounds from their structural descriptor

    Directory of Open Access Journals (Sweden)

    MOHAMMAD H. FATEMI

    2011-07-01

    Full Text Available Quantitative structure–activity relationship (QSAR approaches were used to estimate the volume of distribution (Vd using an artificial neural network (ANN. The data set consisted of the volume of distribution of 129 pharmacologically important compounds, i.e., benzodiazepines, barbiturates, nonsteroidal anti-inflammatory drugs (NSAIDs, tricyclic anti-depressants and some antibiotics, such as betalactams, tetracyclines and quinolones. The descriptors, which were selected by stepwise variable selection methods, were: the Moriguchi octanol–water partition coefficient; the 3D-MoRSE-signal 30, weighted by atomic van der Waals volumes; the fragment-based polar surface area; the d COMMA2 value, weighted by atomic masses; the Geary autocorrelation, weighted by the atomic Sanderson electronegativities; the 3D-MoRSE – signal 02, weighted by atomic masses, and the Geary autocorrelation – lag 5, weighted by the atomic van der Waals volumes. These descriptors were used as inputs for developing multiple linear regressions (MLR and artificial neural network models as linear and non-linear feature mapping techniques, respectively. The standard errors in the estimation of Vd by the MLR model were: 0.104, 0.103 and 0.076 and for the ANN model: 0.029, 0.087 and 0.082 for the training, internal and external validation test, respectively. The robustness of these models were also evaluated by the leave-5-out cross validation procedure, that gives the statistics Q2 = 0.72 for the MLR model and Q2 = 0.82 for the ANN model. Moreover, the results of the Y-randomization test revealed that there were no chance correlations among the data matrix. In conclusion, the results of this study indicate the applicability of the estimation of the Vd value of drugs from their structural molecular descriptors. Furthermore, the statistics of the developed models indicate the superiority of the ANN over the MLR model.

  19. Synthesis and solid state structures of Chalcogenide compounds of Imidazolin-2-ylidene-1,1-Diphenyl-phosphinamine

    Indian Academy of Sciences (India)

    Naktode Kishor; Suman Das; Abhinanda Kundu; Hari Pada Nayek; Tarun K Panda

    2016-03-01

    We report the synthesis and solid state structures of 1,3-di-aryl-imidazolin-2-ylidine-1,1-diphenylphosphinamine [(aryl=mesityl (1a) and aryl=2,6-diisopripyl (1b)] and their chalcogenide compounds 3-di-aryl-imidazolin-2-ylidine-P, P-diphenylphosphinicamide (2a,b), 1,3-di-aryl-imidazolin-2-ylidine-P,P diphenyl-phosphinothioicamide (3a,b) and 1,3-diaryl-imidazolin-2-ylidine-P,P -diphenyl-phosphinoselenoicamide (4a,b).The compounds 1a,b were prepared in good yield by the reaction of 1,3-di-aryl-imidazolin-2-imine and chlorodiphenylphosphine in the presence of triethylamine in toluene. The reactions of 1a,b with elemental sulphur and selenium afforded the corresponding chalcogenide compounds 3a,b and 4a,b respectively.The corresponding oxo- derivative (2a,b) was obtained by reacting compound 1a,b with 30% aqueous hydrogen peroxide in THF. The molecular structures of 1a, 2a, 3a and 4a,b have been established by single crystal X-ray diffraction analyses. The molecular structures reveal that even C1–N1–P1 angle (124.62o) in compound 1a is less obtuse compared to the corresponding C1–N1–Si1 angles (157.8o) observed in related N-silylated 2-iminoimidazolines and trimethylsilyl iminophosphoranes. C1–N1–P1 angles are further widened in compounds 2a, 3a, and 4a,b due to the attachment of chalcogen atoms onto phosphorus atom.

  20. Quinoxaline-2-carboxamide as a carrier ligand in two new platinum(ii) compounds: Synthesis, crystal structure, cytotoxic activity and DNA interaction

    NARCIS (Netherlands)

    Marques Gallego, P.; Amparo Gamiz-Gonzalez, M.; Fortea-Pérez, F. R.; Lutz, M.; Spek, A.L.; Pevec, A.; Kozlevar, B.; Reedijk, J.

    2010-01-01

    The search for platinum compounds structurally different from cisplatin has led to two new platinum(II) compounds containing quinoxaline-2-carboxamide as a carrier ligand, i.e. cis-[Pt(qnxca)(MeCN)Cl2] (1) and the [Pt(qnxca−H)(dmso)Cl] (2). Both compounds have been synthesized and characterized usin

  1. Synthesis and structure of bis(-dibenzoyl methanato -O,O′) (aquo-O) dioxouranium (VI) compound

    Indian Academy of Sciences (India)

    S Kannan; M G B Drew

    2014-09-01

    The compound [UO2(C6H5COCHCOC6H5)2.H2O] was synthesized and characterized by IR, 1H NMR and CHN analysis. Structure of the compound shows that the uranium atom is surrounded by seven oxygen atoms in a pentagonal bi-pyramidal geometry. The water molecule is hydrogen bonded to another molecule via the uranyl and -diketonate oxygen atoms to give a linear zig-zag arrangement along the `a' axis. The whole molecule is stabilized in solid state by various intermolecular hydrogen bonding interactions.

  2. Interactions of the Calcite {10.4} Surface with Organic Compounds: Structure and Behaviour at Mineral – Organic Interfaces

    DEFF Research Database (Denmark)

    Hakim, S. S.; Olsson, M. H. M.; Sørensen, H. O.

    2017-01-01

    The structure and the strength of organic compound adsorption on mineral surfaces are of interest for a number of industrial and environmental applications, oil recovery, CO2 storage and contamination remediation. Biomineralised calcite plays an essential role in the function of many organisms...... that control crystal growth with organic macromolecules. Carbonate rocks, composed almost exclusively of calcite, host drinking water aquifers and oil reservoirs. In this study, we examined the ordering behaviour of several organic compounds and the thickness of the adsorbed layers formed on calcite {10...

  3. Crystal structures of multidrug-resistant HIV-1 protease in complex with two potent anti-malarial compounds

    Energy Technology Data Exchange (ETDEWEB)

    Yedidi, Ravikiran S.; Liu, Zhigang; Wang, Yong; Brunzelle, Joseph S.; Kovari, Iulia A.; Woster, Patrick M.; Kovari, Ladislau C.; Gupta, Deepak (LECOM); (WSI); (NWU); (MUSC); (WSU)

    2012-06-19

    Two potent inhibitors (compounds 1 and 2) of malarial aspartyl protease, plasmepsin-II, were evaluated against wild type (NL4-3) and multidrug-resistant clinical isolate 769 (MDR) variants of human immunodeficiency virus type-1 (HIV-1) aspartyl protease. Enzyme inhibition assays showed that both 1 and 2 have better potency against NL4-3 than against MDR protease. Crystal structures of MDR protease in complex with 1 and 2 were solved and analyzed. Crystallographic analysis revealed that the MDR protease exhibits a typical wide-open conformation of the flaps (Gly48 to Gly52) causing an overall expansion in the active site cavity, which, in turn caused unstable binding of the inhibitors. Due to the expansion of the active site cavity, both compounds showed loss of direct contacts with the MDR protease compared to the docking models of NL4-3. Multiple water molecules showed a rich network of hydrogen bonds contributing to the stability of the ligand binding in the distorted binding pockets of the MDR protease in both crystal structures. Docking analysis of 1 and 2 showed a decrease in the binding affinity for both compounds against MDR supporting our structure-function studies. Thus, compounds 1 and 2 show promising inhibitory activity against HIV-1 protease variants and hence are good candidates for further development to enhance their potency against NL4-3 as well as MDR HIV-1 protease variants.

  4. Magnetic structures of R{sub 2}RhSi{sub 3} (R=Ho, Er) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bazela, W.; Wawrzynska, E.; Penc, B.; Stuesser, N.; Szytula, A.; Zygmunt, A

    2003-10-06

    Powder X-ray and neutron diffraction and magnetic measurements have been performed on R{sub 2}RhSi{sub 3} (R=Ho and Er) compounds at low temperatures. The compounds crystallize in a derivative of the hexagonal AlB{sub 2}-type structure. The crystal structure parameters have been refined on the basis of the X-ray and neutron diffraction patterns collected in the paramagnetic region. These compounds are antiferromagnets with Neel temperatures of 5.2 K for Ho{sub 2}RhSi{sub 3} and 5 K for Er{sub 2}RhSi{sub 3}. Both compounds exhibit collinear magnetic structures, described by the propagation vector k=(1/2,0,0) for Ho{sub 2}RhSi{sub 3} and k=(0,0,0) for Er{sub 2}RhSi{sub 3}. This magnetic order is stable in the temperature ranges between 1.5 K and the Neel temperature.

  5. Fumigant toxicity of cassia and cinnamon oils and cinnamaldehyde and structurally related compounds to Dermanyssus gallinae (Acari: Dermanyssidae).

    Science.gov (United States)

    Na, Young Eun; Kim, Soon-Il; Bang, Hea-Son; Kim, Byung-Seok; Ahn, Young-Joon

    2011-06-10

    The toxicity of two cassia oils, four cinnamon oils and (E)-cinnamaldehyde and (E)-cinnamic acid and 34 structurally related compounds to adult Dermanyssus gallinae (De Geer) collected from a poultry house was examined using a vapour-phase mortality bioassay. Results were compared with those of dichlorvos, a conventional acaricide. The cassia and cinnamon oils (cinnamon technical, cinnamon #500, cassia especial, cassia true, cinnamon bark and cinnamon green leaf) exhibited good fumigant toxicity (LD(50), 11.79-26.40 μg cm(-3)). α-Methyl-(E)-cinnamaldehyde (LD(50), 0.45 μg cm(-3)) and (E)-cinnamaldehyde (0.54 μg cm(-3)) were the most toxic compounds and the toxicity of these compounds was comparable to that of dichlorvos (0.30 μg cm(-3)). Potent fumigant toxicity was also observed in allyl cinnamate, ethyl-α-cyanocinnamate, (E)-2-methoxylcinnamic acid and (Z)-2-methoxylcinnamic acid (LD(50), 0.81-0.92 μg cm(-3)). Structure-activity relationships indicate that structural characteristics, such as types of functional groups and carbon skeleton rather than vapour pressure parameter, appear to play a role in determining toxicity. The essential oils and compounds described merit further study as potential acaricides for the control of D. gallinae populations as fumigants with contact action due to global efforts to reduce the level of highly toxic synthetic acaricides in the agricultural environment.

  6. Densities of L-Glutamic Acid HCl Drug in Aqueous NaCl and KCl Solutions at Different Temperatures

    Science.gov (United States)

    Ryshetti, Suresh; Raghuram, Noothi; Rani, Emmadi Jayanthi; Tangeda, Savitha Jyostna

    2016-04-01

    Densities (ρ ) of (0.01 to 0.07) {mol}{\\cdot } {kg}^{-1} L-Glutamic acid HCl (L-HCl) drug in water, and in aqueous NaCl and KCl (0.5 and 1.0) {mol}{\\cdot } {kg}^{-1} solutions have been reported as a function of temperature at T = (298.15, 303.15, 308.15, and 313.15) K and atmospheric pressure. The accurate density (ρ ) values are used to estimate the various parameters such as the apparent molar volume (V_{2,{\\upphi }}), the partial molar volume (V2^{∞}), the isobaric thermal expansion coefficient (α 2), the partial molar expansion (E2^{∞}), and Hepler's constant (partial 2V2^{∞}/partial T2)P. The Cosphere overlap model is used to understand the solute-solvent interactions in a ternary mixture (L-HCl drug + NaCl or KCl + water). Hepler's constant (partial 2V2^{∞}/partial T2)_P is utilized to interpret the structure-making or -breaking ability of L-HCl drug in aqueous NaCl and KCl solutions, and the results are inferred that L-HCl drug acts as a structure maker, i.e., kosmotrope in aqueous NaCl solutions and performs as a structure breaker, i.e., chaotrope in aqueous KCl solutions.

  7. Synthesis and crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, Gerzon E., E-mail: gerzon@ula.ve [Laboratorio de Cristalografía, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Quintero, Eugenio; Tovar, Rafael; Grima-Gallardo, Pedro; Quintero, Miguel [Centro de Estudio de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of)

    2014-11-15

    Highlights: • New quaternary compound. • Synthesis from solid state reaction. • Crystal structure. • Rietveld refinement. - Abstract: The crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}, belonging to the system I–II{sub 2}–III–VI{sub 4}, was characterized by Rietveld refinement using X-ray powder diffraction data. The powder pattern was composed by 84.5% of the principal phase AgFe{sub 2}GaTe{sub 4} and 15.5% of the secondary phase FeTe. This material crystallizes with stannite structure in the tetragonal space group I-42m (N° 121), Z = 2, unit cell parameters a = 6.3409(2) Å, c = 12.0233(4) Å, V = 483.42(3) Å{sup 3}, and is isostructural with CuFe{sub 2}InSe{sub 4}.

  8. Crystal structure of caesium hydrogen (L)-aspartate and an overview of crystalline compounds of aspartic acid with inorganic constituents

    Energy Technology Data Exchange (ETDEWEB)

    Fleck, M. [Universitaet Wien (Austria). Institut fuer Mineralogie und Kristallographie; Emmerich, R.; Bohaty, L. [Universitaet zu Koeln (Austria). Institut fuer Kristallographie

    2010-08-15

    The crystal structure of the new polar compound caesium hydrogen (L)-aspartate, Cs(C{sub 4}H{sub 6}NO{sub 4}), (abbreviated: Cs(L -AspH)) was determined from single crystal X-ray diffraction data; it comprises two crystallographically different L -AspH anions that are connected via caesium cations to form a three dimensional framework. The Cs ions are irregularly sevenfold[Cs1O{sub 7}] respectively eightfold[Cs2O{sub 8}] coordinated to all {alpha}- and {beta}- carboxylate oxygen atoms. Cs(L -AspH) represents a novel structure type of its own, as do most compounds of (L)-aspartic acid with inorganic constituents. A brief summary of such structurally known aspartates is given. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Structural, electronic and elastic properties of RERu2 (RE=Pr and Nd) Laves phase intermetallic compounds

    Science.gov (United States)

    Shrivastava, Deepika; Sanyal, Sankar P.

    2016-05-01

    We have performed the first-principles calculations to study the structural, electronic and elastic properties of RERu2 (RE = Pr and Nd) Laves phase intermetallic compounds using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA) for exchange and correlation potential. The optimized lattices constant are in reasonable agreement with available experimental data. The electronic properties are analyzed in terms of band structures, total and partial density of states, which confirm their metallic character. The calculated elastic constants infer that these compounds are mechanically stable in C15 (MgCu2 type) structure and found to be ductile in nature.

  10. Structural, electronic and elastic properties of RERu{sub 2} (RE=Pr and Nd) Laves phase intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Deepika, E-mail: deepika89shrivastava@gmail.com; Sanyal, Sankar P. [Department of Physics, Barkatullah university, Bhopal, 462026 (India)

    2016-05-06

    We have performed the first-principles calculations to study the structural, electronic and elastic properties of RERu{sub 2} (RE = Pr and Nd) Laves phase intermetallic compounds using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA) for exchange and correlation potential. The optimized lattices constant are in reasonable agreement with available experimental data. The electronic properties are analyzed in terms of band structures, total and partial density of states, which confirm their metallic character. The calculated elastic constants infer that these compounds are mechanically stable in C15 (MgCu{sub 2} type) structure and found to be ductile in nature.

  11. Atomic structure and electronic properties of the two-dimensional (Au ,Al )/Si (111 )2 ×2 compound

    Science.gov (United States)

    Gruznev, D. V.; Bondarenko, L. V.; Matetskiy, A. V.; Tupchaya, A. Y.; Chukurov, E. N.; Hsing, C. R.; Wei, C. M.; Eremeev, S. V.; Zotov, A. V.; Saranin, A. A.

    2015-12-01

    A combination of scanning tunneling microscopy, angle-resolved photoelectron spectroscopy, ab initio random structure searching, and density functional theory electronic structure calculations was applied to elucidate the atomic arrangement and electron band structure of the (Au ,Al )/Si (111 )2 ×2 two-dimensional compound formed upon Al deposition onto the mixed 5 ×2 /√{3 }×√{3 } Au/Si(111) surface. It was found that the most stable 2 ×2 -(Au, Al) compound incorporates four Au atoms, three Al atoms, and two Si atoms per 2 ×2 unit cell. Its atomic arrangement can be visualized as an array of meandering Au atomic chains with two-thirds of the Al atoms incorporated into the chains and one-third of the Al atoms interconnecting the chains. The compound is metallic and its electronic properties can be controlled by appropriate Al dosing since energetic location of the bands varies by ˜0.5 eV during increasing of Al contents. The 2 ×2 -(Au, Al) structure appears to be lacking the C3 v symmetry typical for the hexagonal lattices. The consequence of the peculiar atomic structure of the two-dimensional alloy is spin splitting of the metallic states, which should lead to anisotropy of the current-induced in-plane spin polarization.

  12. ToxAlerts: a Web server of structural alerts for toxic chemicals and compounds with potential adverse reactions.

    Science.gov (United States)

    Sushko, Iurii; Salmina, Elena; Potemkin, Vladimir A; Poda, Gennadiy; Tetko, Igor V

    2012-08-27

    The article presents a Web-based platform for collecting and storing toxicological structural alerts from literature and for virtual screening of chemical libraries to flag potentially toxic chemicals and compounds that can cause adverse side effects. An alert is uniquely identified by a SMARTS template, a toxicological endpoint, and a publication where the alert was described. Additionally, the system allows storing complementary information such as name, comments, and mechanism of action, as well as other data. Most importantly, the platform can be easily used for fast virtual screening of large chemical datasets, focused libraries, or newly designed compounds against the toxicological alerts, providing a detailed profile of the chemicals grouped by structural alerts and endpoints. Such a facility can be used for decision making regarding whether a compound should be tested experimentally, validated with available QSAR models, or eliminated from consideration altogether. The alert-based screening can also be helpful for an easier interpretation of more complex QSAR models. The system is publicly accessible and tightly integrated with the Online Chemical Modeling Environment (OCHEM, http://ochem.eu). The system is open and expandable: any registered OCHEM user can introduce new alerts, browse, edit alerts introduced by other users, and virtually screen his/her data sets against all or selected alerts. The user sets being passed through the structural alerts can be used at OCHEM for other typical tasks: exporting in a wide variety of formats, development of QSAR models, additional filtering by other criteria, etc. The database already contains almost 600 structural alerts for such endpoints as mutagenicity, carcinogenicity, skin sensitization, compounds that undergo metabolic activation, and compounds that form reactive metabolites and, thus, can cause adverse reactions. The ToxAlerts platform is accessible on the Web at http://ochem.eu/alerts, and it is constantly

  13. SYNTHESES AND STRUCTURES OF AGLNS2 (LN=SM-YB) COMPOUNDS

    NARCIS (Netherlands)

    VANDERLEE, A; VANDEBELT, R; WIEGERS, GA

    1992-01-01

    The ternary compounds AgLnS2 (Ln = Sm-Yb) have been synthesized and characterized. It has been found, in accordance with a previous study, that all compounds, except AgYbS2, are monoclinic with a almost-equal-to b almost-equal-to 7.7 angstrom, c almost-equal-to 12 angstrom and 90-degrees

  14. Interrelation between electronic structure and interatomic distances for RMn2X2 compounds

    Science.gov (United States)

    Gerasimov, E. G.; Kanomata, T.; Gaviko, V. S.

    2007-03-01

    The heat capacity was studied for LaMn2Si2, La0.75Y0.25Mn2Si2, La0.7Y0.3Mn2Si2, YMn2Si2 and LaFe2Si2 isostructural intermetallic compounds in the temperature range 1.8-360 K. The electronic, magnetic and lattice contributions to the heat capacity of the compounds were determined and analyzed. The interrelation was found between values of the electronic contribution to the heat capacity (density of states at the Fermi level) and crystal lattice parameters of R(Mn,Fe,Ni)2Si2 compounds. The electronic contribution and the density of states at Fermi level increase with increasing lattice parameters of the compounds. The change of interlayer Mn-Mn exchange interactions with change of Y concentration in La1-xYxMn2Si2 compounds is not accompanied by considerable changes in the electronic contribution to the heat capacity and density of states at the Fermi level. The performed analysis of the magnetic contribution shows that no essential differences exist between the behavior of the heat capacity of the compounds with d⩾dc and with d

  15. Quick estimation of heats of detonation of aromatic energetic compounds from structural parameters.

    Science.gov (United States)

    Keshavarz, Mohammad Hossein

    2007-05-08

    In this paper, a simple procedure is introduced for a quick and reliable estimation of detonation heats of aromatic energetic compounds without considering heats of formation of energetic compounds. This method does not use any experimental or computed data of energetic materials. The methodology assumes that the heat of detonation of an energetic compound with composition of C(a)H(b)N(c)O(d) can be obtained from the number of nitrogens, ratios of oxygen to carbon and hydrogen to oxygen as well as the contribution of some specific functional groups. There is no need to use any assumed decomposition products to calculate heats of detonation for energetic compounds. Predicted heats of detonation of pure energetic compounds with the product H(2)O in the liquid state for 31 aromatic energetic compounds have a root mean square (rms) of deviation of 0.32 kJ/g from experiment. The new method gives good results with respect to two empirical methods which use measured heats of formation of explosives with two sets of decomposition gases.

  16. Synthesis, Structures and Properties of Cobalt Thiocyanate Coordination Compounds with 4-(hydroxymethylpyridine as Co-ligand

    Directory of Open Access Journals (Sweden)

    Stefan Suckert

    2016-04-01

    Full Text Available Reaction of Co(NCS2 with 4-(hydroxymethylpyridine (hmpy leads to the formation of six new coordination compounds with the composition [Co(NCS2(hmpy4] (1, [Co(NCS2(hmpy4] × H2O (1-H2O, [Co(NCS2(hmpy2(EtOH2] (2, [Co(NCS2(hmpy2(H2O2] (3, [Co(NCS2(hmpy2]n∙4 H2O (4 and [Co(NCS2(hmpy2]n (5. They were characterized by single crystal and powder X-ray diffraction experiments, thermal and elemental analysis, IR and magnetic measurements. Compound 1 and 1-H2O form discrete complexes, in which the Co(II cations are octahedrally coordinated by two terminal thiocyanato anions and four 4-(hydroxymethylpyridine ligands. Discrete complexes were also observed for compounds 2 and 3 where two of the hmpy ligands were substituted by solvent, either water (3 or ethanol (2. In contrast, in compounds 4 and 5, the Co(II cations are linked into chains by bridging 4-(hydroxymethylpyridine ligands. The phase purity was checked with X-ray powder diffraction. Thermogravimetric measurements showed that compound 3 transforms into 5 upon heating, whereas the back transformation occurs upon resolvation. Magnetic measurements did not show any magnetic exchange via the hmpy ligand for compound 5.

  17. Three new bismuth(III) pyridine-2,6-dicarboxylate compounds: Synthesis, characterization and crystal structures

    Science.gov (United States)

    Hakimi, Mohammad; Motieiyan, Elham; Bertolotti, Federica; Marabello, Domenica; Nunes Rodrigues, Vitor Hugo

    2015-11-01

    Three new metal-organic compounds containing bismuth and pyridine-2,6-dicarboxylate (pydc) formulated as (2-apyH)2[Bi(pydc)2(pydcH)]·2H2O, 1, (4-apyH)[Bi(pydc) (pydcH)2].4H2O, 2 and (pipzeaH)[Bi2(pydc)3(pydcH) (H2O)2]·5H2O, 3, (2-apy = 2-aminopyridine, 4-apy = 4-aminopyridine, pipzea = 2-piperazin-1-ylethanamine), have been synthesized in deionized water and characterized by elemental analysis (C, H and N), spectral (UV-Vis, IR), 1H NMR spectroscopy, TGA and single crystal X-ray diffraction. These compounds were obtained via proton transfer methodology. Compounds 1 and 2 have similar monomeric bismuth coordination units, whereas compound 3 has a dimeric bismuth coordination unit. The compounds are anionic in 1 and 2 and they are connected non-covalently to 2-apyH and 4-apyH, respectively. In 3, two molecules are present, one neutral and one anionic, and both are connected non-covalently to pipzeaH cations. Five different coordination modes of Bi-pydc exist in 1, 2 and 3. These compounds are stabilized in the solid state by a complex network of hydrogen bonds between crystallization water molecules, anionic, cationic and neutral fragments, forming 3D-supramolecular arrays.

  18. Structure-Triggered High Quantum Yield Luminescence and Switchable Dielectric Properties in Manganese(II) Based Hybrid Compounds.

    Science.gov (United States)

    Wang, Zhong-Xia; Li, Peng-Fei; Liao, Wei-Qiang; Tang, Yuanyuan; Ye, Heng-Yun; Zhang, Yi

    2016-04-01

    Two new manganese(II) based organic-inorganic hybrid compounds, C11H21Cl3MnN2 (1) and C11H22Cl4MnN2 (2), with prominent photoluminescence and dielectric properties were synthesized by solvent modulation. Compound 1 with novel trigonal bipyramidal geometry exhibits bright red luminescence with a lifetime of 2.47 ms and high quantum yield of 35.8 %. Compound 2 with tetrahedral geometry displays intense long-lived (1.54 ms) green light emission with higher quantum yield of 92.3 %, accompanied by reversible solid-state phase transition at 170 K and a distinct switchable dielectric property. The better performance of 2 results from the structure, including a discrete organic cation moiety and inorganic metal anion framework, which gives the cations large freedom of motion.

  19. Isolation, structure elucidation and enzyme inhibition studies of a new hydroxy ester and other compounds from Berberis jaeschkeana Schneid stem.

    Science.gov (United States)

    Alamzeb, Muhammad; Khan, M Rafiullah; Mamoon-Ur-Rashid; Ali, Saqib; Khan, Ashfaq Ahmad

    2015-01-01

    Bioassay-guided isolation and fractionation of Berberis jaeschkeana Schneid var. jaeschkeana stem resulted in the isolation and characterisation of a new long chain hydroxy ester named as berberinol (1) along with six known compounds (2-7). All the structures were established from 1D and 2D spectroscopic data. Crude extract, sub-fractions and all the isolated compounds were evaluated for their anti-fungal and urease enzyme inhibition properties. All of the sub-fractions and compounds showed good anti-fungal and urease enzyme inhibition properties. Minimum inhibitory concentrations (MICs) were calculated for all active samples in case of urease enzyme inhibition. MICs values were found to be in the range of 39.03-49.78 μg/mL for urease enzyme inhibition.

  20. Anti-inflammatory effects and structure elucidation of two new compounds from Astragalus membranaceus (Fisch) Bge. var. mongholicus (Bge) Hsiao

    Science.gov (United States)

    Wang, Qing-Hu; Han, Na-Ren-Chao-Ke-Tu; Dai, Na-Yin-Tai; Wang, Xiu-Lan; Ao, Wu-Li-Ji

    2014-09-01

    Phytochemical study of the ethanol extract of Astragalus membranaceus (Fisch) Bge. var. mongholicus (Bge) Hsiao resulted to the isolation of two new compounds, 1-hydroxy-5-methylolbenzol-2-O-β-D-glucoside (1) and (3R, 4R)-4,7-hydroxy-2‧,3‧-dimethoxyisoflavane-4‧-O-β-D-glucoside (2). The structure of the isolated compounds were elucidated on the basis of the spectroscopic methods including UV, IR, ESI-MS, 1D NMR and 2D NMR techniques, and by comparison with those reported in the literature. The new compounds were investigated for its effect against inflammation induced by egg-albumin and carrageenan in rats.

  1. Organic compounds as corrosion inhibitors for mild steel in acidic media: correlation between inhibition efficiency and chemical structure

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Elizandra C.S.; Chrisman, Erika C.A.N. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Escola de Quimica

    2009-12-19

    The use of inhibitors for mild steels corrosion control which are in contact with aggressive environment is an accepted practice in acid treatment of oil-wells. Organic compounds have been studied to evaluate their corrosion inhibition potential. Film-forming corrosion inhibitors, commonly used to protect oil-field equipment, can be absorbed on the steel surface to give structurally ordered layers. Therefore, the electrons should act as an important role for this adsorption. Studies reveal that organic compounds show significant inhibition efficiency. For this purpose, their molecules should contain N, O and S heteroatoms in various functional groups, long hydrocarbon linear or branched radical and anion and cation active components. However, most of these compounds are not only expensive but also toxic to living beings. According to the 'Green Chemistry' rules, corrosion inhibitors based on organic compounds should be cheap, with low toxicity and have high inhibition efficiency. In this study, the effects of some organic compounds with different groups such as amide, ether, phenyldiamine, anime and aminophenol on the corrosion behavior of mild steel in acidic media have been investigated. The experimental data were obtained by gravimetric measurements. The results show that these compounds reveal a promising corrosion inhibition where phenyldiamine is the most efficient. The effect of molecular structure on the corrosion inhibition efficiency was investigated by semi-empirical quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, and LUMO-HOMO energy gap orbital density were calculated. The relations between the inhibition efficiency and some quantum parameters are discussed and correlations are proposed. The highest values for the HOMO densities were found in the vicinity nitrogen atom, indicating that it is the most probable adsorption center

  2. Isolation and structural elucidation of cytotoxic compounds from the root bark of Diospyros quercina (Baill.) endemic to Madagascar

    Institute of Scientific and Technical Information of China (English)

    Fatiany Pierre Ruphin; Robijaona Baholy; Randrianarivo Emmanuel; Raharisololalao Amelie; Marie-Therese Martin; Ngbolua Kotote-Nyiwa

    2014-01-01

    Objective:To isolate and characterize the cytotoxic compounds from Diospyros quercina (Baill.) G.E. Schatz&Lowry (Ebenaceae). Methods: An ethno-botanical survey was conducted in the south of Madagascar from July to August 2010. Bio-guided fractionation assay was carried out on the root bark of Diospyros quercina, using cytotoxicity bioassay on murine P388 leukemia cell lines as model. The structures of the cytotoxic compounds were elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. Results: Biological experiments resulted in the isolation of three bioactive pure compounds (named TR-21, TR-22, and TR-23) which exhibited very good in vitro cytotoxic activities with the IC50 values of (0.017 5±0.0060) µg/mL, (0.089±0.005) µg/mL and (1.027±0.070) µg/mL respectively. Thus, they support the claims of traditional healers and suggest the possible correlation between the chemical composition of this plant and its wide use in Malagasy folk medicine to treat cancer. Conclusions:The ability of isolated compounds in this study to inhibit cell growth may represent a rational explanation for the use of Diospyros quercina root bark in treating cancer by Malagasy traditional healers. Further studies are, therefore, necessary to evaluate the in vivo anti-neoplastic activity of these cytotoxic compounds as effective anticancer drugs.

  3. FP-LAPW based investigation of structural, electronic and mechanical properties of CePb{sub 3} intermetallic compound

    Energy Technology Data Exchange (ETDEWEB)

    Pagare, Gitanjali, E-mail: gita-pagare@yahoo.co.in; Jain, Ekta, E-mail: jainekta05@gmail.com [Department of Physics, Government M. L. B. Girls P. G. Autonomous College, Bhopal 462002 (India); Abraham, Jisha Annie, E-mail: disisjisha@yahoo.com [Department of Physics, National Defence Academy, Pune 411023 (India); Sanyal, Sankar P., E-mail: sps.physicsbu@gmail.com [Department of Physics, Barkatullah University, Bhopal 462026 (India)

    2015-08-28

    A theoretical study of structural, electronic, elastic and mechanical properties of CePb{sub 3} intermetallic compound has been investigated systematically using first principles density functional theory. The calculations are carried out within the three different forms of generalized gradient approximation (GGA) and LSDA for the exchange correlation potential. The ground state properties such as lattice parameter (a{sub 0}), bulk modulus (B) and its pressure derivative (B′) are calculated and obtained lattice parameter of this compound shows well agreement with the experimental results. We have calculated three independent second order elastic constants (C{sub 11}, C{sub 12} and C{sub 44}), which has not been calculated and measured yet. From energy dispersion curves, it is found that the studied compound is metallic in nature. Ductility of this compound is analyzed using Pugh’s criteria and Cauchy's pressure (C{sub 11}-C{sub 12}). The mechanical properties such as Young's modulus, shear modulus, anisotropic ratio, Poison's ratio have been calculated for the first time using the Voigt–Reuss–Hill (VRH) averaging scheme. The average sound velocities (v{sub m}), density (ρ) and Debye temperature (θ{sub D}) of this compound are also estimated from the elastic constants.

  4. Two new CuI compounds with zwitterionic tetrazolate ligand: In situ synthesis, crystal structures, luminescence and photocatalytic properties

    Science.gov (United States)

    Zhang, Jian-Yong; Xing, Yuan-Yuan; Wang, Qing-Wei; Zhang, Na; Deng, Wei; Gao, En-Qing

    2015-12-01

    Two 2D new Cu(I) coordination polymers, namely [Cu2(mpTZ)2Br2]·H2O (1), and [Cu2(mpTZ)2N3]ClO4 (2) (mpTZ=N-methyl-4-pyridinium tetrazolate) have been synthesized under solvothermal conditions, in which the mpTZ ligands and CuI ions were obtained through in situ [2+3] cycloaddition reaction and reduction reaction of CuII salts, respectively. Both compounds have been structural characterized by single crystal X-ray diffraction, FT-IR, PXRD and EA. Compound 1 exhibits a 2D neutral coordination network, in which the CuI ions are bridged by η3-1, 2, 4-tetrazolate into 2D sheet. In compound 2, the CuI ions are linked by azide (in μ3-1, 1, 3 bridging mode) and tetrazolate (in η3-1, 2, 3 bridging mode) anions into 2D positively charged sheet, extended along the bc plane. Both compounds 1 and 2 exhibit intense bluish green luminescence in the solid state. Photocatalytic performances of the two compounds for the degradation of methylene blue (MB) under visible light were also investigated and the MB degradation in the presence of 1 was nearly complete (99%) after 150 min.

  5. Correlation between structural studies and third order NLO properties of selected new quinolinium semi-organic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bouchouit, K., E-mail: karim.bouchouit@laposte.net [Departement de Chimie, Faculte des Sciences, Universite de Jijel (Algeria); Bendeif, E.E. [Laboratoire de Cristallographie, Resonance Magnetique et Modelisation CRM2 CNRS UMR 7036, Institut Jean Barriol, Nancy Universite, Faculte des Sciences, BP 239, 54506 Vandoeuvre-les-Nancy, CEDEX (France); EL Ouazzani, H. [Institut des Sciences et Technologies Moleculaires d' Angers UMR CNRS 6200 MOLTECH ANJOU, Universite d' Angers 2, Boulevard Lavoisier, 49045 Angers (France); Dahaoui, S.; Lecomte, C. [Laboratoire de Cristallographie, Resonance Magnetique et Modelisation CRM2 CNRS UMR 7036, Institut Jean Barriol, Nancy Universite, Faculte des Sciences, BP 239, 54506 Vandoeuvre-les-Nancy, CEDEX (France); Benali-cherif, N. [Laboratoire des Structures, Proprietes et Interactions Inter Atomiques (LASPI2A), Centre Universitaire de Khenchela, 40000 Khenchela (Algeria); Sahraoui, B. [Institut des Sciences et Technologies Moleculaires d' Angers UMR CNRS 6200 MOLTECH ANJOU, Universite d' Angers 2, Boulevard Lavoisier, 49045 Angers (France)

    2010-09-14

    Graphical abstract: Organic quinolinium moieties build a zigzag layers in compounds (II) - Abstract: New quinolinium semi-organic compounds of formula (C{sub 9}H{sub 8}N){sub 2}{sup +}.SO{sub 4}{sup 2-},H{sub 2}O (I) (bis-quinolinium sulphate monohydrate) and (C{sub 9}H{sub 8}N){sup +}.NO{sub 3}{sup -} (II) (quinolinium nitrate) have been synthesized and characterized by UV-Vis absorption spectroscopy, nonlinear optical (NLO) measurements and by single crystal X-ray diffraction. The third order nonlinear optical properties of (I) and (II) were investigated using two methods: the degenerate four wave mixing technique (DFWM) performed in solution at {lambda} = 532 nm and the third-harmonic generation (THG) measurements carried out on thin films at {lambda} = 1064 nm. The NLO measurements showed that compound (I) presents better nonlinear optical properties compared to compound (II). To understand further the optical behaviour of (I) and (II), the crystal structures of both compounds were determined from accurate single crystal X-ray diffraction measurements performed at 100 K. The crystallographic studies revealed the key role of the intermolecular interactions and the molecular arrangements in the enhancement of the NLO properties.

  6. Inorganic-organic hybrid compounds based on octamolybdates and multidentate N-donor ligand: syntheses, structures, photoluminescence and photocatalysis.

    Science.gov (United States)

    Kan, Wei-Qiu; Yang, Jin; Liu, Ying-Ying; Ma, Jian-Fang

    2012-08-28

    Six inorganic-organic hybrid compounds, namely, [Cu(2)(2,4'-tmbpt)(2)(β-Mo(8)O(26))(H(2)O)(2)]·7H(2)O (1), [Cu(2,4'-tmbpt)(γ-Mo(8)O(26))(0.5)(H(2)O)]·H(2)O (2), [Co(2,4'-Htmbpt)(2)(γ-Mo(8)O(26))(H(2)O)(2)] (3), [Zn(2,4'-Htmbpt)(2)(γ-Mo(8)O(26))(H(2)O)(2)] (4), [Ni(2,4'-tmbpt)(α-Mo(8)O(26))(0.5)(H(2)O)]·2.5H(2)O (5) and [Ag(2,4'-Htmbpt)(β-Mo(8)O(26))(0.5)] (6), have been synthesized under hydrothermal conditions (2,4'-tmbpt = 1-((1H-1,2,4-triazol-1-yl)methyl)-3-(2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole). The structures of compounds 1-6 have been determined by single-crystal X-ray diffraction analyses and characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) analyses and thermogravimetric analyses (TGA). Compound 1 shows a 3D (3,4)-connected framework constructed by the 2D Cu(II)-organic fragments and [β-Mo(8)O(26)](4-) anions. Compound 2 exhibits a 2D layer structure based on Cu(II)-organic chains and [γ-Mo(8)O(26)] chains. The layers are extended into a 3D supramolecular framework by hydrogen-bonding interactions. Compounds 3 and 4 are isostructural, and display 1D chain structures. The chains are further interlinked by hydrogen-bonding interactions to form 3D supramolecular architectures. Compound 5 shows a 3D framework based on the 2D Ni(II)-organic fragments and [α-Mo(8)O(26)](4-) anions. In compound 6, the 1D chains constructed by the Ag(I) ions, 2,4'-Htmbpt ligands and [β-Mo(8)O(26)](4-) anions are extended by hydrogen-bonding interactions into a 2D supramolecular layer. Each layer threads into the adjacent layers, yielding a 2D → 3D interdigitated structure. Moreover, the photoluminescent properties of 4 and 6, the optical band gaps of 1-6, and the photocatalytic properties of 1-6 have also been investigated.

  7. Synthesis, crystal structures and magnetic properties of fluorite-related compounds Ce3MO7 (M = Nb, Ta)

    Science.gov (United States)

    Inabayashi, Masaki; Doi, Yoshihiro; Wakeshima, Makoto; Hinatsu, Yukio

    2017-10-01

    Ternary oxides Ce3NbO7 and Ce3TaO7 were successfully synthesized by the solid state reaction under flowing hydrogen atmosphere. The structures were determined by the powder X-ray diffraction. Both the compounds were crystallized in the orthorhombic space groups Pnma (for Ce3NbO7) and Cmcm (for Ce3TaO7). Both the structures have similar features: two kinds of infinite chains formed by corner-sharing NbO6 (TaO6) octahedra and edge-sharing Ce(1)O8 cubes, the slabs consisting of alternate chains, and 7-coordinated Ce(2) ions existing between the slabs. In the structure of Ce3NbO7, the NbO6 octahedra running along the a-axis are titled towards the 0 0 1 direction, while in the Ce3TaO7 structure, the TaO6 octahedra running along the c-axis are titled towards the 0 1 0 direction. Magnetic susceptibility measurements for Ce3NbO7 and Ce3TaO7 show that both compounds are paramagnetic down to 1.8 K, and confirm that the Ce ion is in the trivalent state. From specific heat (Cp) measurements, a rapid increase of Cp/T has been observed below 3 K for both the compounds, indicating the onset of magnetic ordering between Ce3+ ions at further lower temperatures.

  8. Void-induced dissolution in molecular dynamics simulations of NaCl and water.

    Science.gov (United States)

    Bahadur, Ranjit; Russell, Lynn M; Alavi, Saman; Martin, Scot T; Buseck, Peter R

    2006-04-21

    To gain a better understanding of the interaction of water and NaCl at the surface during dissolution, we have used molecular dynamics to simulate the interface with two equal-sized slabs of solid NaCl and liquid water in contact. The introduction of voids in the bulk of the salt, as well as steps or pits on the surface of the NaCl slab results in a qualitative change of system structure, as defined by radial distribution functions (RDFs). As an example, the characteristic Na-Na RDF for the system changes from regularly spaced narrow peaks (corresponding to an ordered crystalline structure), to a broad primary and smaller secondary peak (corresponding to a disordered structure). The change is observed at computationally short time scales of 100 ps, in contrast with a much longer time scale of 1 mus expected for complete mixing in the absence of defects. The void fraction (which combines both bulk and surface defects) required to trigger dissolution varies between 15%-20% at 300 K and 1 atm, and has distinct characteristics for the physical breakdown of the crystal lattice. The void fraction required decreases with temperature. Sensitivity studies show a strong dependence of the critical void fraction on the quantity and distribution of voids on the surface, with systems containing a balanced number of surface defects and a rough surface showing a maximum tendency to dissolve. There is a moderate dependence on temperature, with a 5% decrease in required void fraction with a 100 K increase in temperature, and a weak dependence on water potential model used, with the SPC, SPC/E, TIP4P, and RPOL models giving qualitatively identical results. The results were insensitive to the total quantity of water available for dissolution and the duration of the simulation.

  9. Void-induced dissolution in molecular dynamics simulations of NaCl and water

    Science.gov (United States)

    Bahadur, Ranjit; Russell, Lynn M.; Alavi, Saman; Martin, Scot T.; Buseck, Peter R.

    2006-04-01

    To gain a better understanding of the interaction of water and NaCl at the surface during dissolution, we have used molecular dynamics to simulate the interface with two equal-sized slabs of solid NaCl and liquid water in contact. The introduction of voids in the bulk of the salt, as well as steps or pits on the surface of the NaCl slab results in a qualitative change of system structure, as defined by radial distribution functions (RDFs). As an example, the characteristic Na-Na RDF for the system changes from regularly spaced narrow peaks (corresponding to an ordered crystalline structure), to a broad primary and smaller secondary peak (corresponding to a disordered structure). The change is observed at computationally short time scales of 100ps, in contrast with a much longer time scale of 1μs expected for complete mixing in the absence of defects. The void fraction (which combines both bulk and surface defects) required to trigger dissolution varies between 15%-20% at 300K and 1atm, and has distinct characteristics for the physical breakdown of the crystal lattice. The void fraction required decreases with temperature. Sensitivity studies show a strong dependence of the critical void fraction on the quantity and distribution of voids on the surface, with systems containing a balanced number of surface defects and a rough surface showing a maximum tendency to dissolve. There is a moderate dependence on temperature, with a 5% decrease in required void fraction with a 100K increase in temperature, and a weak dependance on water potential model used, with the SPC, SPC/E, TIP4P, and RPOL models giving qualitatively identical results. The results were insensitive to the total quantity of water available for dissolution and the duration of the simulation.

  10. Multiple plant-wax compounds record differential sources and ecosystem structure in large river catchments

    Science.gov (United States)

    Hemingway, Jordon D.; Schefuß, Enno; Dinga, Bienvenu Jean; Pryer, Helena; Galy, Valier V.

    2016-07-01

    The concentrations, distributions, and stable carbon isotopes (δ13C) of plant waxes carried by fluvial suspended sediments contain valuable information about terrestrial ecosystem characteristics. To properly interpret past changes recorded in sedimentary archives it is crucial to understand the sources and variability of exported plant waxes in modern systems on seasonal to inter-annual timescales. To determine such variability, we present concentrations and δ13C compositions of three compound classes (n-alkanes, n-alcohols, n-alkanoic acids) in a 34-month time series of suspended sediments from the outflow of the Congo River. We show that exported plant-dominated n-alkanes (C25-C35) represent a mixture of C3 and C4 end members, each with distinct molecular distributions, as evidenced by an 8.1 ± 0.7‰ (±1σ standard deviation) spread in δ13C values across chain-lengths, and weak correlations between individual homologue concentrations (r = 0.52-0.94). In contrast, plant-dominated n-alcohols (C26-C36) and n-alkanoic acids (C26-C36) exhibit stronger positive correlations (r = 0.70-0.99) between homologue concentrations and depleted δ13C values (individual homologues average ⩽-31.3‰ and -30.8‰, respectively), with lower δ13C variability across chain-lengths (2.6 ± 0.6‰ and 2.0 ± 1.1‰, respectively). All individual plant-wax lipids show little temporal δ13C variability throughout the time-series (1σ ⩽ 0.9‰), indicating that their stable carbon isotopes are not a sensitive tracer for temporal changes in plant-wax source in the Congo basin on seasonal to inter-annual timescales. Carbon-normalized concentrations and relative abundances of n-alcohols (19-58% of total plant-wax lipids) and n-alkanoic acids (26-76%) respond rapidly to seasonal changes in runoff, indicating that they are mostly derived from a recently entrained local source. In contrast, a lack of correlation with discharge and low, stable relative abundances (5-16%) indicate that

  11. Novel molecular variants of the Na-Cl cotransporter gene are responsible for Gitelman syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Mastroianni, N.; De Fusco, M.; Casari, G. [Univsersita` di Milano (Italy)] [and others

    1996-11-01

    A hereditary defect of the distal tubule accounts for the clinical features of Gitelman syndrome (GS), an autosomal recessive disease characterized by hypokalemia, hypomagnesemia, metabolic alkalosis, and hypocalciuria. Recently, we cloned the cDNA coding for the human Na-Cl thiazide-sensitive cotransporter (TSC; also known as {open_quotes}NCCT{close_quotes} or {open_quotes}SLC12A3{close_quotes}) as a possible candidate for GS, and Simon et al., independently, described rotation in patients with GS. Now, we show 12 additional mutations consistent with a loss of function of the Na-Cl cotransporter in GS. Two missense replacements, R09W and P349L, are common to both studies and could represent ancient mutations. The other mutations include three deletions, two insertions, and six missense mutations. When all mutations from both studies are considered, missense mutations seem to be more frequently localized within the intracellular domains of the molecule, rather than in transmembrane or extracellular domains. One family, previously reported as a GS form with dominant inheritance, has proved to be recessive, with the affected child being a compound heterozygote. A highly informative intragenic tetranucleotide marker, useful for molecular diagnostic studies, has been identified at the acceptor splice site of exon 9. 12 refs., 3 figs., 2 tabs.

  12. Syntheses and Supramolecular Structures of Two Nickel(Ⅱ) Compounds Based on Two Thiosemicarbazone Ligands

    Institute of Scientific and Technical Information of China (English)

    LI Cheng-juan; FENG Ze-jing; ZHAO Xiao-juan; WANG Su-na; DOU Jian-min

    2013-01-01

    Two new compounds,[Ni2(L1)(Py)6]Py·CH3OH(1) and [Ni3(L2)2(Py)4]·2DMF(2)(H4L1=N,N'-bisalicylbisthiocarbamide; H3L2=3-hydroxyl-2-naphthalene thiosemicarbazide; Py=pyridine; DMF=dimethyl fumarate),based upon two thiosemicarbazone ligands have been obtained and characterized by elemental analysis,Fourier transform infrared(FTIR) and X-ray diffraction(XRD).Compound 1 possesses a binuclear cluster,in which the bisalicylbisthiocarbamide acts as a hexadentate bridge.Compound 2 exhibits a linear trinuclear cluster with the triply-deprotonated ligand acting as pentadentate bridge.C—H…O,C—H…π and C—H…S weak interactions further link these molecules to form interesting supramolecular networks.

  13. Synthesis and biological activity of sulfur compounds showing structural analogy with combretastatin A-4

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Edson dos A. dos; Prado, Paulo C.; Carvalho, Wanderley R. de; Lima, Ricardo V. de; Beatriz, Adilson; Lima, Denis P. de, E-mail: denis.lima@ufms.br [Universidade Federal de Mato Grosso do Sul (UFMS), Campo Grande, MS (Brazil). Departamento de Quimica; Hamel, Ernest [Screening Technologies Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, National Cancer Institute at Frederick, National Institutes of Health, Frederick, MD (United States); Dyba, Marzena A. [Basic Science Program , SAIC-Frederick, Inc., Structural Biophysics Laboratory National Cancer Institute, Frederick, MD (United States); Albuquerque, Sergio [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Faculdade de Ciencias Farmaceuticas

    2013-09-01

    We extended our previous exploration of sulfur bridges as bioisosteric replacements for atoms forming the bridge between the aromatic rings of combretastatin A-4. Employing coupling reactions between 5-iodo-1,2,3-trimethoxybenzene and substituted thiols, followed by oxidation to sulfones with m-CPBA, different locations for attaching the sulfur atom to ring A through the synthesis of nine compounds were examined. Antitubulin activity was performed with electrophoretically homogenous bovine brain tubulin, and activity occurred with the 1,2,3-trimethoxy-4-[(4-methoxyphenyl)thio]benzene (12), while the other compounds were inactive. The compounds were also tested for leishmanicidal activity using promastigote forms of Leishmania braziliensis (MHOM/BR175/M2904),and the greatest activity was observed with 1,2,3-trimethoxy-4-(phenylthio)benzene (10) and 1,2,3-trimethoxy-4-[(4-methoxyphenyl) sulfinyl]benzene (15). (author)

  14. Structurally defined allyl compounds of main group metals: coordination and reactivity.

    Science.gov (United States)

    Lichtenberg, Crispin; Okuda, Jun

    2013-05-10

    Organometallic allyl compounds are important as allylation reagents in organic synthesis, as polymerization catalysts, and as volatile metal precursors in material science. Whereas the allyl chemistry of synthetically relevant transition metals such as palladium and of the lanthanoids is well-established, that of main group metals has been lagging behind. Recent progress on allyl complexes of Groups 1, 2, and 12-16 now provides a more complete picture. This is based on a fundamental understanding of metal-allyl bonding interactions in solution and in the solid state. Furthermore, reactivity trends have been rationalized and new types of allyl-specific reactivity patterns have been uncovered. Key features include 1) the exploitation of the different types of metal-allyl bonding (highly ionic to predominantly covalent), 2) the use of synergistic effects in heterobimetallic compounds, and 3) the adjustment of Lewis acidity by variation of the charge of allyl compounds.

  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. The true structural periodicities and superspace group descriptions of the prototypical incommensurate composite materials: Alkane/urea inclusion compounds

    Science.gov (United States)

    Couzi, Michel; Guillaume, François; Harris, Kenneth D. M.; Palmer, Benjamin A.; Christensen, Kirsten; Collins, Stephen P.

    2016-12-01

    The prototypical family of incommensurate composite materials are the n-alkane/urea inclusion compounds, in which n-alkane guest molecules are arranged in a periodic manner along one-dimensional tunnels in a urea host structure, with an incommensurate relationship between the periodicities of the host and guest substructures along the tunnel. We develop interpretations of the structural periodicities, superspace group descriptions and symmetry properties of the low-temperature phases of n-alkane/urea inclusion compounds, based in part on a high-resolution synchrotron single-crystal X-ray diffraction study of n-nonadecane/urea. Specifically, we prove that, on passing from phase I to phase II, the C-centering of the orthohexagonal unit cell is lost for both the host and guest substructures, and that the symmetries of all phases I, II and III are described completely by (3 + 1)-dimensional superspace groups.

  17. Theoretical investigations of electronic structure and magnetism in Zr{sub 2}CoSn full-Heusler compound

    Energy Technology Data Exchange (ETDEWEB)

    Birsan, A. [National Institute of Materials Physics, Atomistilor Str., No. 105 bis PO Box MG-7, 077125 Magurele (Romania); University of Bucharest, Faculty of Physics, Atomistilor Str., No. 105 PO Box MG-11, 077125 Magurele (Romania); Kuncser, V. [National Institute of Materials Physics, Atomistilor Str., No. 105 bis PO Box MG-7, 077125 Magurele (Romania)

    2015-08-15

    The half-metallic properties of a new and promising full-Heusler compound, Zr{sub 2}CoSn, are investigated by means of ab initio calculations within the Density Functional Theory framework. It was shown that the ferromagnetic ordered Hg{sub 2}CuTi-type crystal structure is energetically the most favorable for this compound. The total magnetic moment is 3 μ{sub B}/f.u. and follows a typical Slater–Pauling dependence. The half metallicity disappears if the unit cell volume is contracted by more than 5%. - Highlights: • Electronic structure and magnetic properties of Zr{sub 2}CoSn were investigated. • The calculated equilibrium lattice parameter is a=6.76 Å • The total magnetic moment of Zr{sub 2}CoSn is 3 μ{sub B}/f.u. • Full spin polarization is at the ground state.

  18. Structural, spectroscopic characterization of (E)-4-chloro-2-((4-methoxybenzylidene)amino)phenol as potential antioxidant compound

    Science.gov (United States)

    Şen, Fatih; Efil, Kürşat; Bekdemir, Yunus; Dinçer, Muharrem

    2017-01-01

    A new imine derivative, (E)-4-chloro-2-((4-methoxybenzylidene)amino)phenol has been synthesized from the reaction of 4-Anisaldehyde with benzoyl 2-Amino-4-chlorophenol. The results of a combined experimental and DFT investigations of the structural and spectroscopic properties of the title compound are given. The crystal and molecular investigations are performed by X-ray diffraction and spectral results obtained by IR, NMR and UV-Vis spectrometers. The structural geometry, vibration frequencies, 1H and 13C NMR chemical shifts, UV-Vis spectral analysis and HOMO-LUMO of molecule in the ground state have been also calculated using the density functional theory (DFT) employing B3LYP exchange correlation with the 6-311G+(d, p) basis set, and check aganist the experimental data. The stability of antioxidant at different concentrations of compound are evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method and determined its specific absorbance properties.

  19. Quaternary equiatomic compounds LnZnSbO(Ln=La-Nd, Sm) with ZrCuSiAs-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Wollesen, P.; Kaiser, J.W.; Jeitschko, W. [Muenster Univ. (Germany). Anorganisch-Chemisches Inst.

    1997-12-01

    The five compounds LnZnSbO (Ln = La - Nd, Sm) were prepared by annealing cold-pressed pellets of the lanthanoids, zinc oxide, and antimony, or by reacting these components in a NaCl/KCl flux. They crystallize with the tetragonal ZrCuSiAs type structure, which was refined from single-crystal X-ray data of CeZnSbO : P 4/nmm, a = 419.76(4), c = 947.4(1) pm, Z = 2, R = 0.022 for 165 structure factors and 12 variable parameters. Chemical bonding in this and the formally isotypic compound CeZn{sub 1-x}Sb{sub 2} is briefly discussed. (orig.) 36 refs.

  20. Structural stability and bonding in TMOs2 (TM=Sc and Y) C14 Laves phase compounds

    Science.gov (United States)

    Acharya, Nikita; Shrivastava, Deepika; Sanyal, Sankar P.

    2017-05-01

    The structural, electronic as well as bonding nature of TMOs2 (TM=Sc and Y) Laves phase compounds are studied using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA). These compounds are crystallize in MgZn2-type hexagonal structure. The total energy are calculated using Birch Murnaghan's equation of state to find the equilibrium lattice parameter (a0), Bulk modulus (B0) and pressure derivative of bulk modulus (B0) and are in good agreement with experimental results. The electronic properties reveal that ScOs2 and YOs2 are highly metallic. The charge density difference plots represent ionic as well as metallic bonding, with weak covalent character.

  1. Electronic structure and magnetic properties of PuMGa5 compounds within the LDA + U + SO method

    Science.gov (United States)

    Lukoyanov, A. V.; Shorikov, A. O.; Anisimov, V. I.; Dremov, V. V.

    2012-12-01

    The electronic structure and magnetic properties of PuMGa5 compounds (M = Co, Fe, Ni, Rh, Ir) have been calculated within the LDA + U + SO method taking into account the strong electron-electron correlations and the spin-orbit coupling in the 5 f shell of the actinide metal. The features of the electronic structure, coupling type, electron configuration, and magnetic state of the plutonium ion have been considered depending on the type of transition metal in PuMGa5. The estimates of the effective magnetic moment of the plutonium ion agree well with the known experimental values. It has been shown that the occupancy of d states of the transition metal correlates with the appearance of superconductivity in the compounds of this class, providing the optimum doping regime in the electronic subsystem.

  2. Magnetic structure and bonding of rare-earth diboride compounds RB{sub 2}: First-principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Kacimi, S.; Zazoua, F.; Djermouni, M.; Zaoui, A. [Modelling and Simulation in Materials Science Laboratory, Djillali Liabes University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria); Bekkouche, B. [Signals and Systems Laboratory, Abdelhamid Ibn Badis University of Mostaganem, Mostaganem 27000 (Algeria); Boukortt, A. [Elaboration Characterization Physico-Mechanics of Materials and Metallurgical Laboratory ECP3M, Faculty of Sciences and Technology, Abdelhamid Ibn Badis University of Mostaganem, Mostaganem 27000 (Algeria)

    2012-07-15

    The electronic structure and magnetic behavior of hexagonal rare-earth diboride RB{sub 2} are studied using ab initio density-functional theory in the DFT + U approach. The effect of the spin-orbit coupling is also investigated and it is found to be a necessary requirement for the accurate description of the magnetic moment. In this paper, we study the magnetic phase stability of RB{sub 2} compounds; the band structure and the density of state (DOS) results prove that the coulomb potential and the spin-orbit interaction are keys factors to understand the magnetic properties of these series of materials. In addition, we also explain the behavior of a chemical bond of RB{sub 2} compounds through the analysis of the DOS and of the charge density. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Crystal and magnetic structure of the R{sub 15}Si{sub 9}C compounds (R = Ho, Er, Tb)

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, C [Institut Laue-Langevin, BP 156, F-38042 Grenoble (France); Wrubl, F; Pani, M; Manfrinetti, P [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, I-16146 Genova (Italy); Hill, A H, E-mail: ritter@ill.fr, E-mail: chimfis@chimica.unige.it [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France)

    2011-07-27

    The synthesis of the new compounds R{sub 15}Si{sub 9}C with R = Sm, Gd-Er, Y and R{sub 15}Ge{sub 9}C with R = Ce, Pr and Nd has been recently reported; these compounds crystallize in the hexagonal La{sub 15}Ge{sub 9}Fe structure type, hP50-P6{sub 3}mc, Z = 2 (ordered superstructure of La{sub 5}Ge{sub 3} (Mn{sub 5}Si{sub 3}-type, hP 16-P6{sub 3}/mcm, Z = 2)). Here we report the results of a neutron diffraction investigation that we have performed to study the crystal and magnetic structures of the R{sub 15}Si{sub 9}C compounds with R = Tb, Ho and Er. All three compounds see the establishment of commensurate magnetic order with a predominantly ferromagnetic interaction. Details of mixed antiferro-ferromagnetic spin arrangements ({kappa} = [000]) (for Tb{sub 15}Si{sub 9}C and Ho{sub 15}Si{sub 9}C) or of purely ferromagnetic ordering (Er{sub 15}Si{sub 9}C), and of their temperature dependence, are given and linked to the different coordination of the four dissimilar rare earth sites. In the Tb and Ho compounds the thermal evolution of the magnetic moment values strongly differs between the different R sites. The position occupied by the principal carbon has been determined (Wyckoff site 2b) and the existence of a second position available for the interstitial carbon (Wyckoff site 2a) has been revealed for R = Ho, Tb. Moreover, in the Tb and Ho compounds the magnetic moment value of the rare earth site R4, surrounding the second interstitial carbon site, is strongly reduced if compared to the value on the other rare earth sites. The magnetic transition temperatures of all three compounds, i.e. T{sub C} = 130, 43 and 45 K for Tb{sub 15}Si{sub 9}C, Ho{sub 15}Si{sub 9}C and Er{sub 15}Si{sub 9}C, are remarkably high compared to those of the parent R{sub 5}Si{sub 3} compounds. The magnetic behaviour of the partly filled Tb{sub 5}Si{sub 3}C{sub 0.25} is reported.

  4. Crystal Structure and Photochromism of a Novel Organic Compound Condensed by Pyrazolone with Thiosemicarbazide

    Institute of Scientific and Technical Information of China (English)

    LIU, Guang-Fei; LIU, Lang; JlA, Dian-Zeng; ZHANG, Li

    2006-01-01

    A new photochromic organic compound of thiosemicarbazone, 4-(p-bromo-α-methylaminothiocarbonyl hydrazonobenzal)-2,5-dihydro-3-methyl-5-oxo-l-phenyl pyrazole, was synthesized and characterized by elemental analyses, IR, 1H NMR spectra, and X-ray single-crystal diffraction analysis. The compound exhibited an interesting photochromism in the solid state when irradiated by ultraviolet light at 365 nm. The photochromic kinetics was studied by the time-dependent powder UV-Vis reflectance spectra. The intermolecular and intramolecular hydrogen-bonding interactions may be responsible for the photochromic phenomenon.

  5. CORRELATION OF THE STRUCTURAL PECULIARITIES OF BIOACTIVE COMPOUNDS OF HERBAL REMEDY AND ITS PHARMACOLOGICAL VALUE

    Directory of Open Access Journals (Sweden)

    Shulga L.I.

    2012-06-01

    Full Text Available Fatty acids in lipophilic fractions of the herbal composition as well as of the tincture obtained from it were detected and identified by the method of gas chromatography. The presence of this group of biologically active compounds supplements the biological value of the herbal medicine since fatty acids are responsible for the manifestation of antimicrobial properties along with flavonoids and volatile compounds. An antimicrobial activity of extraction agents was experimentally determined in regard to gram-positive and gram-negative microorganisms.

  6. Electronic structure studies of ferro-pnictide superconductors and their parent compounds using angle-resolved photoemission spectroscopy (ARPES)

    Energy Technology Data Exchange (ETDEWEB)

    Setti, Thirupathaiah

    2011-07-14

    The discovery of high temperature superconductivity in the iron pnictide compound LaO{sub 1-x}F{sub x}FeAs with T{sub c} = 26 K as created enormous interest in the high-T{sub c} superconductor community. So far, four prototypes of crystal structures have been found in the Fe-pnictide family. All four show a structural deformation followed or accompanied by a magnetic transition from a high temperature paramagnetic conductor to a low temperature antiferromagnetic metal whose transition temperature T{sub N} varies between the compounds. Charge carrier doping, isovalent substitution of the As atoms or the application of pressure suppresses the antiferromagnetic spin density wave (SDW) order and leads to a superconducting phase. More recently high Tc superconductivity has been also detected in iron chalchogenides with similar normal state properties. Since superconductivity is instability of the normal state, the study of normal state electronic structure in comparison with superconducting state could reveal important information on the pairing mechanism. Therefore, it is most important to study the electronic structure of these new superconductors, i.e., to determine Fermi surfaces and band dispersions near the Fermi level at the high symmetry points in order to obtain a microscopic understanding of the superconducting properties. Using the technique angle-resolved photoemission spectroscopy (ARPES) one measures the electrons ejected from a sample when photons impinge on it. In this way one can map the Fermi surface which provides useful information regarding the physics behind the Fermi surface topology of high T{sub c} superconductors. Furthermore, this technique provides information on the band dispersion, the orbital character of the bands, the effective mass, the coupling to bosonic excitations, and the superconducting gap. This emphasizes the importance of studying the electronic structure of the newly discovered Fe-pnictides using ARPES. In this work we have

  7. Quinoxaline N,N'-dioxide derivatives and related compounds as growth inhibitors of Trypanosoma cruzi. Structure-activity relationships.

    Science.gov (United States)

    Aguirre, Gabriela; Cerecetto, Hugo; Di Maio, Rossanna; González, Mercedes; Alfaro, María Elena Montoya; Jaso, Andrés; Zarranz, Belén; Ortega, Miguel Angel; Aldana, Ignacio; Monge-Vega, Antonio

    2004-07-16

    Quinoxaline derivatives presented good inhibitor activity of growth of Trypanosoma cruzi in in vitro assays. The 50% inhibitory doses were of the same order of that of Nifurtimox. Derivative 13, a quinoxaline N,N'-dioxide derivative, and the reduced derivatives 19 and 20 were the most cytotoxic compounds against the protozoan. Structural requirements for optimal activity were studied by computational methods. From statistical analysis we could establish a multiple correlation between activity and lipophilic properties and LUMO energy.

  8. Structure determination of a novel metal-organic compound synthesized from aluminum and 2,5-pyridinedicarboxylic acid

    DEFF Research Database (Denmark)

    Ståhl, Kenny; Brink, Bastian; Andersen, Jonas

    2011-01-01

    The structure of [Al2(pydc)2(μ2-OH)2(H2O)2]n(pydc=2,5-pyridinedicarboxylate) was successfully determined from powder X-ray diffraction data. The compound crystallizes in the triclinic system (space group P -1) with a=6.7813(1) A° , b=7.4944(1) A°, c=8.5013(1) A° , α=95.256(1)°, β=102.478(1)°, γ=1...

  9. A set of triple-resonance nuclear magnetic resonance experiments for structural characterization of organophosphorus compounds in mixture samples

    Energy Technology Data Exchange (ETDEWEB)

    Koskela, Harri, E-mail: Harri.T.Koskela@helsinki.fi [VERIFIN, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)

    2012-11-02

    Highlights: Black-Right-Pointing-Pointer New {sup 1}H, {sup 13}C, {sup 31}P triple-resonance NMR pulse experiments. Black-Right-Pointing-Pointer Analysis of organophosphorus (OP) compounds in complex matrix. Black-Right-Pointing-Pointer Selective extraction of {sup 1}H, {sup 31}P, and {sup 13}C chemical shifts and connectivities. Black-Right-Pointing-Pointer More precise NMR identification of OP nerve agents and their degradation products. - Abstract: The {sup 1}H, {sup 13}C correlation NMR spectroscopy utilizes J{sub CH} couplings in molecules, and provides important structural information from small organic molecules in the form of carbon chemical shifts and carbon-proton connectivities. The full potential of the {sup 1}H, {sup 13}C correlation NMR spectroscopy has not been realized in the Chemical Weapons Convention (CWC) related verification analyses due to the sample matrix, which usually contains a high amount of non-related compounds obscuring the correlations of the relevant compounds. Here, the results of the application of {sup 1}H, {sup 13}C, {sup 31}P triple-resonance NMR spectroscopy in characterization of OP compounds related to the CWC are presented. With a set of two-dimensional triple-resonance experiments the J{sub HP}, J{sub CH} and J{sub PC} couplings are utilized to map the connectivities of the atoms in OP compounds and to extract the carbon chemical shift information. With the use of the proposed pulse sequences the correlations from the OP compounds can be recorded without significant artifacts from the non-OP compound impurities in the sample. Further selectivity of the observed correlations is achieved with the application of phosphorus band-selective pulse in the pulse sequences to assist the analysis of multiple OP compounds in mixture samples. The use of the triple-resonance experiments in the analysis of a complex sample is shown with a test mixture containing typical scheduled OP compounds, including the characteristic degradation

  10. Prediction of Setschenow constants of N-heteroaromatics in NaCl solutions based on the partial charge on the heterocyclic nitrogen atom.

    Science.gov (United States)

    Yang, Bin; Li, Zhongjian; Lei, Lecheng; Sun, Feifei; Zhu, Jingke

    2016-02-01

    The solubilities of 19 different kinds of N-heteroaromatic compounds in aqueous solutions with different concentrations of NaCl were determined at 298.15 K with a UV-vis spectrophotometry and titration method, respectively. Setschenow constants, Ks, were employed to describe the solubility behavior, and it is found that the higher ring numbers of N-heteroaromatics gave rise to the lower values of Ks. Moreover, Ks showed a good linear relationship with the partial charge on the nitrogen atom (QN) for either QN > 0 or QN coefficient (Kow). The heterocyclic N in N-heteroaromatics may interact with Na(+) ions in NaCl solution for QN 0.

  11. Modeling skills of pre-service chemistry teachers in predicting the structure and properties of inorganic chemistry compounds

    Science.gov (United States)

    Nursa'adah, Euis; Liliasari, Mudzakir, Ahmad

    2016-02-01

    The focus of chemistry is learning about the composition, properties, and transformations of matters. Modeling skills are required to comprehend structure and chemical composition in submicroscopic size. Modeling skills are abilities to produce chemical structure and to explain it into the macroscopic phenomenon and submicroscopic representations. Inorganic chemistry is a study of whole elements in the periodic table and their compounds, except carbon compounds and their derivatives. Knowledge about the structure and properties of chemical substances is a basic model for students in studying inorganic chemistry. Furthermore, students can design and produce to utilize materials needed in their life. This research aimed to describes modeling skills of pre-service chemistry teachers. In order, they are able to determine and synthesize useful materials. The results show that students' modeling skills were in a low level and unable connecting skill categories, even the models of inorganic compounds common. These phenomena indicated that students only describe each element when they learn inorganic chemistry. So that it will make modeling skills of students low. Later, another researches are necessary to develop learning design of inorganic chemistry based on good modeling skills of students.

  12. Crystal and magnetic structure of TbFe{sub 0.25}Ge{sub 2} compound

    Energy Technology Data Exchange (ETDEWEB)

    Gil, A., E-mail: a.gil@ajd.czest.pl [Faculty of Mathematics and Natural Sciences, Jan Długosz University in Częstochowa, Armii Krajowej 13/15, 42-200 Częstochowa (Poland); Hoser, A. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14-109 Berlin (Germany); Penc, B.; Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków (Poland)

    2013-10-15

    The crystal and magnetic structure of polycrystalline TbFe{sub 0.25}Ge{sub 2} sample have been determined. X-ray and neutron diffraction studies indicate that this compound has the orthorhombic CeNiSi{sub 2}-type crystal structure (space group Cmcm). The magnetic ordering, based on the neutron diffraction data in low temperature, is described by two components: a collinear antiferromagnetic G-type and a cosine-wave modulated one. In the collinear G-type structure the Tb magnetic moment is equal to 3.81(5) µ{sub B} and it is parallel to the c-axis. The modulated structure is described by the propagation vector k=(0.460(8), 0, 0.305(1)), the Tb magnetic moment equals 7.75(8) µ{sub B,} lies in b–c and forms an angle 23(2)° with the c-axis. The collinear component decreases to zero at 22.6 K while the modulated one at 190.8 K. - Highlights: • We determine crystal and magnetic structure of TbFe{sub 0.25}Ge{sub 2} compound. • We compare the results with other TbT{sub x}Ge{sub 2} compounds. • We observe the complex magnetic structure in TbFe{sub 0.25}Ge{sub 2} with two components: collinear and cosine-wave modulated. • T (3d) element have got significant influence on the interactions in Tb sublattice.

  13. Ab initio study on structures and stabilities of OLi_nhyperlithiated compounds

    Institute of Scientific and Technical Information of China (English)

    郑祥娥; 王志中; 唐敖庆

    1999-01-01

    The geometries of hyperlithiated compounds OLin were optimized by means of HF, MP2 and DFT methods with 6-31G basis set. The dissociation energies of those optimized stable geometries of OLin were calculated, the results are in good agreement with experimental values; and moreover, the dissociation energy of OLi6 is predicted. In addition, the fundamental vibrational frequencies were also predicted.

  14. Vibrational spectra and structural considerations of compounds NaLnTiO4

    NARCIS (Netherlands)

    Blasse, G.; Heuvel, G.P.M. van den

    1974-01-01

    The Raman and infrared spectra of compounds NaLnTiO4 (Ln = lanthanide, including yttrium) are reported and discussed. Their most striking feature is a strong band in both spectra at about 900 cm−1. This band is ascribed to a vibration localized in the Ti---O bond directed towards the Na---O layers.

  15. Synthesis, Structure and Properties of Melamine-Based pTHF-Urethane Supramolecular Compounds

    NARCIS (Netherlands)

    Öjelund, Karin; Loontjens, Ton; Steeman, Paul; Palmans, Anja; Maurer, Frans

    2003-01-01

    The properties of melamine based supramolecular compounds have been studied with rheological, thermal, mechanical, dielectric and scattering techniques and compared with similar covalently bonded materials. The complexes are based on a linear pTHF-diol (M¯n=1 000) connected via a diisocyanate with m

  16. Antimutagenic Compounds of White Shrimp (Litopenaeus vannamei): Isolation and Structural Elucidation

    Science.gov (United States)

    López-Saiz, Carmen-María; Hernández, Javier; Cinco-Moroyoqui, Francisco-Javier; Velázquez, Carlos; Ocaño-Higuera, Víctor-Manuel; Plascencia-Jatomea, Maribel; Robles-Sánchez, Maribel; Machi-Lara, Lorena; Burgos-Hernández, Armando

    2016-01-01

    According to the World Health Organization, cancer is the main cause of mortality worldwide; thus, the search of chemopreventive compounds to prevent the disease has become a priority. White shrimp (Litopenaeus vannamei) has been reported as a source of compounds with chemopreventive activities. In this study, shrimp lipids were extracted and then fractionated in order to isolate those compounds responsible for the antimutagenic activity. The antimutagenic activity was assessed by the inhibition of the mutagenic effect of aflatoxin B1 on TA98 and TA100 Salmonella tester strains using the Ames test. Methanolic fraction was responsible for the highest antimutagenic activity (95.6 and 95.9% for TA98 and TA100, resp.) and was further separated into fifteen different subfractions (M1–M15). Fraction M8 exerted the highest inhibition of AFB1 mutation (96.5 and 101.6% for TA98 and TA100, resp.) and, after further fractionation, four subfractions M8a, M8b, M8c, and M8d were obtained. Data from 1H and 13C NMR, and mass spectrometry analysis of fraction M8a (the one with the highest antimutagenic activity), suggest that the compound responsible for its antimutagenicity is an apocarotenoid. PMID:27006678

  17. Sulfated phenolic compounds from Limonium caspium: Isolation, structural elucidation, and biological evaluation

    Science.gov (United States)

    Three new compounds, 5-methyldihydromyricetin (1), 5-methyldihydromyricetin-3'-O-sulfate (2) and ß-D-glucopyranoside, 3-methyl, but-3-en-1-yl 4-O-a-L-rhamnopyranosyl (3) have been isolated from the Limonium caspium, together with dihydromyricetin (4), dihydromyricetin-3'-O-sulfate (5), myricetin-3'-...

  18. Antimutagenic Compounds of White Shrimp (Litopenaeus vannamei: Isolation and Structural Elucidation

    Directory of Open Access Journals (Sweden)

    Carmen-María López-Saiz

    2016-01-01

    Full Text Available According to the World Health Organization, cancer is the main cause of mortality worldwide; thus, the search of chemopreventive compounds to prevent the disease has become a priority. White shrimp (Litopenaeus vannamei has been reported as a source of compounds with chemopreventive activities. In this study, shrimp lipids were extracted and then fractionated in order to isolate those compounds responsible for the antimutagenic activity. The antimutagenic activity was assessed by the inhibition of the mutagenic effect of aflatoxin B1 on TA98 and TA100 Salmonella tester strains using the Ames test. Methanolic fraction was responsible for the highest antimutagenic activity (95.6 and 95.9% for TA98 and TA100, resp. and was further separated into fifteen different subfractions (M1–M15. Fraction M8 exerted the highest inhibition of AFB1 mutation (96.5 and 101.6% for TA98 and TA100, resp. and, after further fractionation, four subfractions M8a, M8b, M8c, and M8d were obtained. Data from 1H and 13C NMR, and mass spectrometry analysis of fraction M8a (the one with the highest antimutagenic activity, suggest that the compound responsible for its antimutagenicity is an apocarotenoid.

  19. Self-assembled structures in diblock copolymers with hydrogen-bonded amphiphilic plasticizing compounds

    NARCIS (Netherlands)

    Valkama, Sami; Ruotsalainen, Teemu; Nykanen, Antti; Laiho, Ari; Kosonen, Harri; ten Brinke, Gerrit; Ikkala, Olli; Ruokolainen, Janne; Nykänen, Antti

    2006-01-01

    Hydrogen-bonding amphiphilic low molecular weight plasticizing compounds to one block of diblock copolymers to form supramolecular comblike blocks leads to hierarchical self-assembly at the block copolymer (long) and amphiphile (short) length scales, in which lamellar-in-lamellar order and the

  20. Structure and physical properties of RE{sub 2}AgGe{sub 3} (RE=Ce, Pr, Nd) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Sumanta; Mumbaraddi, Dundappa; Halappa, Pramod; Kalsi, Deepti [New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India); Rayaprol, Sudhindra [UGC-DAE Consortium for Scientific Research, Mumbai Centre, R-5 Shed, BARC Campus, Mumbai 400085 (India); Peter, Sebastian C., E-mail: sebastiancp@jncasr.ac.in [New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India)

    2015-09-15

    We have synthesized the compounds RE{sub 2}AgGe{sub 3} (RE =Ce, Pr, Nd) by arc melting. The crystal structure obtained from single crystal and powder X-ray diffraction suggests that these compounds crystallize in the α-ThSi{sub 2} structure type. The magnetic susceptibility data of Ce{sub 2}AgGe{sub 3} follows Curie–Weiss (CW) law above 25 K without any magnetic ordering down to 2 K. The effective magnetic moment (μ{sub eff}) was calculated as 2.53 μ{sub B}/Ce and negative Curie paramagnetic temperature (θ{sub p})=−2.4 K hint weak antiferromagnetic coupling among the adjacent spins. Pr{sub 2}AgGe{sub 3} shows a complex magnetic behavior wherein the magnetic susceptibility at field cooled and zero field cooled modes bifurcates at 11.5 K with the latter undergoing a cusp like maxima, probably due to weak ferromagnetic interaction. The θ{sub p} and μ{sub eff} obtained are 4 K and 4.33 μ{sub B}/Pr, respectively. Nd{sub 2}AgGe{sub 3} undergoes multiple magnetic transitions. Temperature dependent resistivity data reveals that three compounds are metallic in nature. - Graphical abstract: The compounds Ce{sub 2}AgGe{sub 3}, Pr{sub 2}AgGe{sub 3} and Nd{sub 2}AgGe{sub 3} have been synthesized by arc melting. X-ray diffraction suggests tetragonal α-ThSi{sub 2} type structure and diverse magnetic properties exhibited in the magnetic measurements. - Highlights: • Two new compounds Ce{sub 2}AgGe{sub 3}, Nd{sub 2}AgGe{sub 3} and known Pr{sub 2}AgGe{sub 3} synthesized by arc melting. • Crystal structure of the compounds derived from X-ray diffraction. • Ce{sub 2}AgGe{sub 3} and Pr{sub 2}AgGe{sub 3} exhibit antiferromagnetic ordering. • Nd{sub 2}AgGe{sub 3} shows multiple magnetic transition with ferrimagnetic like behavior.

  1. Two spin-peierls-like compounds exhibiting divergent structural features, lattice compression, and expansion in the low- temperature phase.

    Science.gov (United States)

    Tian, Zhengfang; Duan, Haibao; Ren, Xiaoming; Lu, Changsheng; Li, Yizhi; Song, You; Zhu, Huizhen; Meng, Qingjin

    2009-06-18

    Two quasi-one-dimensional (quasi-1D) compounds, [4'-CH(3)Bz-4-RPy][Ni(mnt)(2)] (mnt(2-) = maleonitriledithiolate), where 4'-CH(3)Bz-4-RPy(+) = 1-(4'-methylbenzyl)pyridinium (denoted as compound 1) and 1-(4'-methylbenzyl)-4-aminopyridinium (denoted as compound 2), show a spin-Peierls-like transition with T(C) approximately 182 K for 1 and T(C) approximately 155 K for 2. The enthalpy changes for the transition are estimated to be DeltaH = 316.6 J.mol(-1) for 1 and 1082.1 J.mol(-1) for 2. From fits to the magnetic susceptibility, the magnetic exchange constants in the gapless state are calculated to be J = 166(2) K with g = 2.020(23) for 1 versus J = 42(0) K with g = 2.056(5) for 2. In the high-temperature (HT) phase, 1 and 2 are isostructural and crystallize in the monoclinic space group P2(1)/c. The nonmagnetic cations and paramagnetic anions form segregated columns with regular anionic and cationic stacks. In the low-temperature (LT) phase, the crystals of the two compounds undergo a transformation to the triclinic space group P-1, and both anionic and cationic stacks dimerize. In the transformation from the HT to LT phases, the two compounds exhibit divergent structural features, with lattice compression for 1 but lattice expansion for 2, due to intermolecular slippage. Combined with our previous studies, it is also noted that the transition temperature, T(C), is qualitatively related to the cell volume in the HT phase for the series of compounds [1-(4'-R-benzylpyridinium][Ni(mnt)(2)] (where R represents the substituent). When there is a single substituent in the para position of benzene, giving a larger cell volume, the transition temperature increases.

  2. Tissue-binding and toxicity of compounds structurally related to the herbicide dichlobenil in the mouse olfactory mucosa.

    Science.gov (United States)

    Eriksson, C; Brandt, I; Brittebo, E

    1992-10-01

    The herbicides dichlobenil (2,6-dichlorobenzonitrile), chlorthiamid (2,6-dichlorothiobenzamide) and their environmental degradation product 2,6-dichlorobenzamide are irreversibly bound and toxic to the olfactory mucosa following single injections in mice (Brandt et al., Toxicology and Applied Pharmacology 1990, 103, 491-501; Brittebo et al., Fundamental and Applied Toxicology 1991, 17, 92-102). In the present study, autoradiography showed an irreversible binding of radioactivity in the olfactory mucosa (preferentially in the Bowman's glands) in C57Bl/6 mice treated with the 14C-labelled analogues [14C]2,6-difluorobenzonitrile ([14C]DFBN) and [14C]2,6-difluorobenzamide ([14C]DFBA). Therefore the toxicity of DFBN, DFBA and of some structurally related compounds including benzonitrile (BN) and the herbicides bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) and ioxynil (3,5-diiodo-4-hydroxybenzonitrile) in the mouse olfactory mucosa was examined. No histopathological changes in the olfactory mucosa or in the liver were observed following a single ip dose of any of these compounds [0.145 mmol/kg (all compounds); 0.58 mmol/kg (DFBN, DFBA and BN)]. Also in mice treated with the glutathione-depleting agent phorone, none of these compounds induced any histopathological changes in the olfactory mucosa. The covalent binding of [14C]DFBN in the olfactory mucosa was 16 times lower than an equimolar toxic dose of [14C]dichlobenil, suggesting a low rate of metabolic activation of DFBN in the olfactory mucosa or a low reactivity of the DFBN metabolites formed. The results of this study thus show that single doses of DFBN, DFBA, BN, IX and BX, compounds structurally related to the potent olfactory toxicant dichlobenil, do not elicit acute toxicity in the olfactory mucosa of mice.

  3. Three-dimensional flow structure and patterns of bed shear stress in an evolving compound meander bend

    Science.gov (United States)

    Engel, Frank; Rhoads, Bruce L.

    2016-01-01

    Compound meander bends with multiple lobes of maximum curvature are common in actively evolving lowland rivers. Interaction among spatial patterns of mean flow, turbulence, bed morphology, bank failures and channel migration in compound bends is poorly understood. In this paper, acoustic Doppler current profiler (ADCP) measurements of the three-dimensional (3D) flow velocities in a compound bend are examined to evaluate the influence of channel curvature and hydrologic variability on the structure of flow within the bend. Flow structure at various flow stages is related to changes in bed morphology over the study timeframe. Increases in local curvature within the upstream lobe of the bend reduce outer bank velocities at morphologically significant flows, creating a region that protects the bank from high momentum flow and high bed shear stresses. The dimensionless radius of curvature in the upstream lobe is one-third less than that of the downstream lobe, with average bank erosion rates less than half of the erosion rates for the downstream lobe. Higher bank erosion rates within the downstream lobe correspond to the shift in a core of high velocity and bed shear stresses toward the outer bank as flow moves through the two lobes. These erosion patterns provide a mechanism for continued migration of the downstream lobe in the near future. Bed material size distributions within the bend correspond to spatial patterns of bed shear stress magnitudes, indicating that bed material sorting within the bend is governed by bed shear stress. Results suggest that patterns of flow, sediment entrainment, and planform evolution in compound meander bends are more complex than in simple meander bends. Moreover, interactions among local influences on the flow, such as woody debris, local topographic steering, and locally high curvature, tend to cause compound bends to evolve toward increasing planform complexity over time rather than stable configurations.

  4. Electronic structure and magnetism of Nd/sub 2/Fe/sub 14/B and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Sellmyer, D.J.; Engelhardt, M.A.; Jaswal, S.S.; Arko, A.J.

    1988-05-16

    The electronic and magnetic structures of Nd/sub 2/Fe/sub 14/B and related compounds have been studied with photoemission spectroscopy and self-consistent spin-polarized electronic structure calculations. The positions of the exchange-split Fe 3d bands and the localized 4f levels were determined. The densities of states in the ferromagnetic and paramagnetic states are essentially identical which provides strong evidence for considerable magnetic short-range order above T/sub c/, as in the fluctuating-band model of itinerant-electron magnetism

  5. Electronic structure of the layer compounds GaSe and InSe in a tight-binding approach

    Science.gov (United States)

    Camara, M. O.; Mauger, A.; Devos, I.

    2002-03-01

    The three-dimensional band structure of the III-VI layer compounds GaSe and InSe has been investigated in the tight-binding approach. The pseudo-Hamiltonian matrix elements in the sp3s* basis are fit in order to reproduce the nonlocal pseudopotential band structure, in the framework of constrained optimization techniques using the conjugate gradient method. The results are in good agreement with the optical and photoemission experimental data. The scaling laws appropriate to the covalent bonding are violated by a fraction of eV only, which suggests that the interlayer interactions are not solely of the van der Waals type.

  6. Interactions between radionuclides and organic colloids. Structure and reactivity of humic compounds; Interactions entre radionucleides et colloides organiques. Structure et reactivite des substances humiques

    Energy Technology Data Exchange (ETDEWEB)

    Plancque, G

    2001-09-01

    Humic compounds are the main organic colloids present in natural waters. These compounds can significantly modify the speciation of metals and control their properties, like migration, toxicity or bio-availability. It is thus important to study their speciation in conditions representative to those encountered in the natural environment. The aim of this work is to analyze the reactivity of these humic compounds. Two spectroscopic techniques have been used: the time-resolution laser spectro-fluorimetry, limited to the study of fluorescent elements, and the electro-spray source mass spectroscopy which requires the development of specific protocols for all elements of the periodic classification system. Europium, a fluorescent element analogue to trivalent actinides, has been chosen as test-metal for the intercomparison of both spectroscopic techniques. The first technique has permitted to determine the inorganic and organic speciation (spectra and lifetime of europium hydroxides and carbonates, and constants of interaction with humic acids, respectively). The limitations of this technique in the study of inorganic speciation has been evidenced. Humic compounds have a badly defined structure. The use of high-resolution mass spectroscopy has permitted to propose in a direct and experimental way, a molecular structure of aquatic fulvic acids in agreement with their known physico-chemical properties. (J.S.)

  7. Structural studies on meiosis-activating sterols and structurally related compounds : potential ligands of the FF-MAS receptor

    NARCIS (Netherlands)

    Boer, D.R.

    2001-01-01

    Meiosis Activating Sterols (MAS) are key regulatory factors in the meiotic cell cycle. Two compounds in this family, Follicular Fluid-MAS (FF-MAS or 4,4-dimethyl-5a-cholest-8,14,24-triene-3b-ol) and Testicular-MAS (T-MAS or 4,4-dimethyl-5a-cholest-8,14-diene-3b-ol), have been isolated and

  8. Structural and magnetic properties of tetragonal Heusler compounds Mn{sub 2-x}Fe{sub 1+x}Ga

    Energy Technology Data Exchange (ETDEWEB)

    Gasi, Teuta; Winterlik, Juergen; Balke, Benjamin; Fecher, Gerhard H.; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes-Gutenberg-University, 55099 Mainz (Germany)

    2011-07-01

    Heusler compounds such as tetragonal phase of Mn{sub 3-x}Ga are currently receiving increased interest. These materials play an important role due to their multifunctional properties and high potential for applications in STT-MRAM technology. STT-MRAMs require high Curie temperatures, low Gilbert damping constants, and low magnetic moments. This contribution focuses on the structural and magnetic properties of tetragonal Heusler compounds Mn{sub 2-x}Fe{sub 1+x}Ga. These compounds are of exceptional importance due to their large diversity of adaptive magnetic properties and their tunability by variation of several physical parameters such as temperature, magnetic field, or electron-doping. The series of samples was successfully synthesized by arc-melting and characterized. The magnetic measurements show that all these materials show high T{sub C}s above 600 K and diverse magnetic hardness. Additionally, we found that the compound Fe{sub 2}MnGa shows magnetic shape memory behavior.

  9. Crystal structure and magnetic properties of Nd(Mn_(1-x)Fe_x)_2Si_2 compounds

    Institute of Scientific and Technical Information of China (English)

    Chen Ye-Qing; Luo Jun; Liang Jing-Kui; Li Jing-Bo; Rao Guang-Hui

    2009-01-01

    X-ray powder diffraction, resistivity and magnetization studies have been performed on polyerystalline Nd(Fe_xMn_(1-x))_2Si_2(0≤x≤1) compounds which crystallize in a ThCr_2Si_2-type structure with the space group 14/mmm. The field-cooled temperature dependence of the magnetization curves shows that, at low temperatures, NdFe_2Si_2 is antiferromagnetic, while the other compounds show ferromagnetic behaviour. The substitution of Fe for Mn leads to a decrease in lattice parameters a, c and unit-cell volume V. The Curie temperature of the compounds first increases, reaches a maximum around x = 0.7, then decreases with Fe content. However, the saturation magnetization decreases monotonically with increasing Fe content. This Fe concentration dependent magnetization of Nd(Fe_xMn_(1-x))_2Si_2 compounds can be well explained by taking into account the complex effect on magnetic properties due to the substitution of Mn by Fe. The temperature's square dependence on electrical resistivity indicates that the curve of Nd(Fe_(0.6)Mn_(0.4))_2Si_2 has a quasi-linear character above its Curie temperature, which is typical of simple metals.

  10. Spectroscopic, structural characterizations and antioxidant capacity of the chromium (III) niacinamide compound as a diabetes mellitus drug model.

    Science.gov (United States)

    Refat, Moamen S; El-Megharbel, Samy M; Hussien, M A; Hamza, Reham Z; Al-Omar, Mohamed A; Naglah, Ahmed M; Afifi, Walid M; Kobeasy, Mohamed I

    2017-02-15

    New binuclear chromium (III) niacinamide compound with chemical formula [Cr2(Nic)(Cl)6(H2O)4]·H2O was obtained upon the reaction of chromium (III) chloride with niacinamide (Nic) in methanol solvent at 60°C. The proposed structure was discussed with the help of microanalytical analyses, conductivity, spectroscopic (FT-IR and UV-vis.), magnetic calculations, thermogravimetric analyses (TG/TGA), and morphological studies (X-ray of solid powder and scan electron microscopy. The infrared spectrum of free niacinamide in comparison with its chromium (III) compound indicated that the chelation mode occurs via both nitrogen atoms of pyridine ring and primary -NH2 group. The efficiency of chromium (III) niacinamide compound in decreasing of glucose level of blood and HbA1c in case of diabetic rats was checked. The ameliorating gluconeogenic enzymes, lipid profile and antioxidant defense capacities are considered as an indicator of the efficiency of new chromium (III) compound as antidiabetic drug model.

  11. Spectroscopic, structural characterizations and antioxidant capacity of the chromium (III) niacinamide compound as a diabetes mellitus drug model

    Science.gov (United States)

    Refat, Moamen S.; El-Megharbel, Samy M.; Hussien, M. A.; Hamza, Reham Z.; Al-Omar, Mohamed A.; Naglah, Ahmed M.; Afifi, Walid M.; Kobeasy, Mohamed I.

    2017-02-01

    New binuclear chromium (III) niacinamide compound with chemical formula [Cr2(Nic)(Cl)6(H2O)4]·H2O was obtained upon the reaction of chromium (III) chloride with niacinamide (Nic) in methanol solvent at 60 °C. The proposed structure was discussed with the help of microanalytical analyses, conductivity, spectroscopic (FT-IR and UV-vis.), magnetic calculations, thermogravimetric analyses (TG/TGA), and morphological studies (X-ray of solid powder and scan electron microscopy. The infrared spectrum of free niacinamide in comparison with its chromium (III) compound indicated that the chelation mode occurs via both nitrogen atoms of pyridine ring and primary -NH2 group. The efficiency of chromium (III) niacinamide compound in decreasing of glucose level of blood and HbA1c in case of diabetic rats was checked. The ameliorating gluconeogenic enzymes, lipid profile and antioxidant defense capacities are considered as an indicator of the efficiency of new chromium (III) compound as antidiabetic drug model.

  12. Identification and structure elucidation of a novel antifungal compound produced by Pseudomonas aeruginosa PGPR2 against Macrophomina phaseolina.

    Science.gov (United States)

    Illakkiam, Devaraj; Ponraj, Paramasivan; Shankar, Manoharan; Muthusubramanian, Shanmugam; Rajendhran, Jeyaprakash; Gunasekaran, Paramasamy

    2013-12-01

    Pseudomonas aeruginosa PGPR2 was found to protect mungbean plants from charcoal rot disease caused by Macrophomina phaseolina. Secondary metabolites from the culture supernatant of P. aeruginosa PGPR2 were extracted with ethyl acetate and the antifungal compound was purified by preparative HPLC using reverse phase chromatography. The purified compound showed antifungal activity against M. phaseolina and other phytopathogenic fungi (Fusarium sp., Rhizoctonia sp. Alternaria sp., and Aspergillus sp.). The structure of the purified compound was determined using (1)H, (13)C, 2D NMR spectra and liquid chromatography-mass spectrometry (LC-MS). Spectral data suggest that the antifungal compound is 3,4-dihydroxy-N-methyl-4-(4-oxochroman-2-yl)butanamide, with the chemical formula C14H17NO5 and a molecular mass of 279. Though chemically synthesized chromanone derivatives have been shown to have antifungal activity, we report for the first time, the microbial production of a chromanone derivative with antifungal activity. This ability of P. aeruginosa PGPR2 makes it a suitable strain for biocontrol.

  13. Synthesis, crystal structure and electrical properties of the new organic-inorganic hybrid compound bis(1-chlorido-4-aminopyridinium) octachlorodiantimoinate

    Science.gov (United States)

    Fersi, Mohamed Amine; Hajji, Rachid; Chaabane, Iskandar; Gargouri, Mohamed

    2017-10-01

    Bis(1-chlorido-4-aminopyridinium) octachlorodiantimoinate has been synthesized and characterized by a single-crystal X-ray diffraction at 296 K and impedance spectroscopy. At room temperature, the title compound is crystallized in the triclinic system (P 1 ̅ space group) with Z = 2 and the following unit cell dimensions: a = 7.919 (1) Å, b = 9.624 (1) Å, c = 17.692 (3) Å, α = 101.81 (1)°, β = 95.12 (1)°and γ = 112.48 (1)°. The crystal structure of the [C10H12Cl2N4]Sb2Cl8 compound is built of two un-equivalent monoprotonated cations [C5H6N2Cl] + and two un-equivalent tetrachloroantimonate (III) anions noted which are [Sb(1)Cl4]- and [Sb(2)Cl4]-. The arrangement of this compound can be described by an alternation of organic and inorganic layers stacked along [010] direction. The cohesion of compound entities is ensured by hydrogen bonding (N-H…. Cl) and Van Der Waals interaction (C-H…. Cl). The temperature dependence of the σdc conductivity exhibits an Arrhenius type behavior described by the following expression σdc T = Aexp(-Ea/kβT). The Ac conductivity and the dielectric loss suggest that the correlated barrier hopping is the appropriate model for the conduction mechanism.

  14. Characterization and structure elucidation of antibacterial compound of Streptomyces sp. ECR77 isolated from east coast of India.

    Science.gov (United States)

    Thirumurugan, D; Vijayakumar, R

    2015-05-01

    Forty marine actinobacteria were isolated from the sediments of east coast (Bay of Bengal) region of Tamilnadu, India. Morphologically distinct colonies were primarily tested against fish pathogenic bacteria such as Vibrio cholerae, V. parahaemolyticus, V. alginolyticus, Pseudomonas fluorescens and Aeromonas hydrophila by cross-streak plate method. The secondary metabolites produced by the highly potential strain cultured on starch casein broth were extracted separately with various solvents such as alcohol, ethyl acetate, methanol, petroleum ether and chloroform. The antibacterial assay of the bioactive compounds was tested against the fish pathogenic bacteria by well diffusion method. Of the various solvents used, the ethyl acetate extract of the isolate had good antibacterial activity. The potential strain was identified as Streptomyces labedae by phenotypic, 16S rRNA gene sequence and phylogenetic analysis. Purification of the biologically active compounds by column chromatography led to isolation of 27 fractions. The biologically active fraction was re-chromatographed on a silica gel column to obtain a single active compound, namely N-isopentyltridecanamide. The structure of the compounds was elucidated on the basis of ultra violet, Fourier transform infrared and nuclear magnetic resonance spectra.

  15. Structure identification for compound I separated and purified from taxoids-produced endophytic fungi (Alternaria. alternata var. taxi 1011)

    Institute of Scientific and Technical Information of China (English)

    XIANG Yong; LIU Jun; LU An-guo; CUI Jing-xia

    2003-01-01

    Endophytic fungi are widely found in almost all kinds of plants. Many endophytic fungi can produce some physiological active compounds, which are same to or analog to those isolated from their hosts. Producing physiological active compounds through microbial fermentation can give a new way to resolve resource limitation and to find out alternative source. Through the methods of organic solvent extraction, thin layer chromatography (TLC) and column chromatography, compound I was isolated, purified from the liquid fermentation metabolites of the taxoids-produced endophytic fungi (Alternaria. alternata var. taxi 1011 Y. Xiang et LU An-guo) that was screened from the bark of Taxus. cuspidata Sieb.et Zucc.. Compound I was identified as one kind of taxoids type III, based on the analyzing results by using the methods of ultraviolet spectroscopy (UV), infrared spectroscopy (IR), mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR). This study provides a completed method for separation and purification of the endophytic fungi as well as structure identification of its fermentation metabolite

  16. Antileishmanial Activity and Structure-Activity Relationship of Triazolic Compounds Derived from the Neolignans Grandisin, Veraguensin, and Machilin G

    Directory of Open Access Journals (Sweden)

    Eduarda C. Costa

    2016-06-01

    Full Text Available Sixteen 1,4-diaryl-1,2,3-triazole compounds 4–19 derived from the tetrahydrofuran neolignans veraguensin 1, grandisin 2, and machilin G 3 were tested against Leishmania (Leishmania amazonensis intracellular amastigotes. Triazole compounds 4–19 were synthetized via Click Chemistry strategy by 1,3-dipolar cycloaddition between terminal acetylenes and aryl azides containing methoxy and methylenedioxy groups as substituents. Our results suggest that most derivatives were active against intracellular amastigotes, with IC50 values ranging from 4.4 to 32.7 µM. The index of molecular hydrophobicity (ClogP ranged from 2.8 to 3.4, reflecting a lipophilicity/hydrosolubility rate suitable for transport across membranes, which may have resulted in the potent antileishmanial activity observed. Regarding structure-activity relationship (SAR, compounds 14 and 19, containing a trimethoxy group, were the most active (IC50 values of 5.6 and 4.4 µM, respectively, with low cytotoxicity on mammalian cells (SI = 14.1 and 10.6. These compounds induced nitric oxide production by the host macrophage cells, which could be suggested as the mechanism involved in the intracellular killing of parasites. These results would be useful for the planning of new derivatives with higher antileishmanial activities.

  17. Filtering and counting of extended connectivity fingerprint features maximizes compound recall and the structural diversity of hits.

    Science.gov (United States)

    Hu, Ye; Lounkine, Eugen; Bajorath, Jürgen

    2009-07-01

    Extended connectivity fingerprints produce variable numbers of structural features for molecules and quantitative comparison of feature ensembles is typically carried out as a measure of molecular similarity. As an alternative way to utilize the information content of extended connectivity fingerprint features, we have introduced a compound class-directed feature filtering technique. In combination with a simple feature counting protocol, feature filtering significantly improves the performance of extended connectivity fingerprint similarity searching compared with state-of-the-art fingerprint search methods. Subsets of extended connectivity fingerprint features that are unique to active compounds are found to be responsible for high compound recall. Moreover, feature filtering and counting is shown to result in significantly higher scaffold hopping potential than data fusion or fingerprint averaging methods. Extended connectivity fingerprint feature filtering and counting represents one of the simplest similarity search methods introduced to date, yet it produces top compound recall and maximizes the scaffold diversity of hits, which is a longstanding goal of similarity searching.

  18. Assessing exchange-correlation functional performance for structure and property predictions of oxyfluoride compounds from first principles

    Science.gov (United States)

    Charles, Nenian; Rondinelli, James M.

    2016-11-01

    Motivated by the resurgence of electronic and optical property design in ordered fluoride and oxyfluoride compounds, we present a density functional theory (DFT) study of 19 materials with structures, ranging from simple to complex, and variable oxygen-to-fluorine ratios. We focus on understanding the accuracy of the exchange-correlation potentials (Vx c) to DFT for the prediction of structural, electronic, and lattice dynamical properties at four different levels of theory, i.e., the local density approximation (LDA), generalized gradient approximation (GGA), metaGGA, and hybrid functional level which includes fractions of exact exchange. We investigate in detail the metaGGA functionals MS2 [Sun et al., Phys. Rev. Lett. 111, 106401 (2013), 10.1103/PhysRevLett.111.106401] and SCAN [Sun et al., Phys. Rev. Lett. 115, 036402 (2015), 10.1103/PhysRevLett.115.036402], and show that although the metaGGAs show improvements over the LDA and GGA functionals in describing the electronic structure and phonon frequencies, the static structural properties of fluorides and oxyfluorides are often more accurately predicted by the GGA-level Perdew-Burke-Ernzerhof functional for solids, PBEsol. Results from LDA calculations are unsatisfactory for any compound, regardless of oxygen concentration. The PBEsol and Heyd-Scuseria-Ernzerhof (HSE06) functionals give good performance in all-oxide or all-fluoride compounds. For the oxyfluorides, PBEsol is consistently more accurate for structural properties across all oxygen concentrations; however, we stress the need for detailed property assessment with various functionals for oxyfluorides with variable composition. The "best" functional is anticipated to be more strongly dependent on the property of interest. Our study provides useful insights in selecting an Vx c that achieves optimal performance compromises, enabling more accurate predictive design of functional fluoride-based materials with density functional theory.

  19. NaCl salinity affects lateral root development in Plantago maritima

    NARCIS (Netherlands)

    Rubinigg, M; Wenisch, J; Elzenga, JTM; Stulen, [No Value

    2004-01-01

    Root growth and morphology were assessed weekly in hydroponically-grown seedlings of the halophyte Plantago maritima L. during exposure to 0, 50, 100 and 200 mM NaCl for 21 d. Relative growth rate was reduced by 25% at 200 mM NaCl. The lower NaCl treatments did not affect relative growth rates. Prim

  20. STEEL CORD WITH A COMPLETE PENETRATION OF COMPOUND INTO THE STRUCTURE

    Directory of Open Access Journals (Sweden)

    A. V. Vedeneev

    2011-01-01

    Full Text Available It is shown that one of the perspective types of metal cord for breaker layer of automobile tires are the constructions with maximal degree of rubber compound penetration at vulcanization. the constructions and technologies of metal cord productions with full rubber penetration (FrP already in the process of treatment into rubber-cord cloth are developed at RUP “BMZ”.

  1. Multiplet effects in the electronic structure of {delta}-Pu, Am and their compounds

    Energy Technology Data Exchange (ETDEWEB)

    Shick, A.; Kolorenc, J.; Drchal, V. [Institut of Physics, ASCR, Prague (Czech Republic); Kolorenc, J. [North Carolina State Univ., Dept. of Physics, Raleigh, NC (United States); Havela, L. [Charles Univ. Dept. of Condensed Matter Physics, Faculty of Mathematics and Physics, Prague (Czech Republic); Gouder, T. [Joint Research Centre, Institute for Transuranium Elements, European Commission, Karlsruhe (Germany)

    2007-01-15

    We propose a straightforward and efficient procedure to perform dynamical mean-field (DMFT) calculations on the top of the static mean-field LDA+U (local density approximation) approximation. Starting from self-consistent LDA+U ground state we included multiplet transitions using the Hubbard-I approximation, which yields a very good agreement with experimental photoelectron spectra of {delta}-Pu, Am, and their selected compounds. (authors)

  2. CRYSTAL-STRUCTURE DETERMINATION OF THE MISFIT LAYER COMPOUND (HOS)1.23NBS2

    NARCIS (Netherlands)

    WIEGERS, GA; MEETSMA, A; HAANGE, RJ; DEBOER, JL

    1992-01-01

    Single-crystal X-ray diffraction has shown that (HoS)1.23NbS2 is a misfit layer compound built of alternate double layers of HoS, approximately a {001} slice of NaCl-type HoS, and sandwiches of NbS2 with niobium in trigonal prisms of sulphur like niobium in 2H-NbS2. The unit cell dimensions of the H

  3. Quantitative Structure Property Relations (QSPR) for Predicting Molar Diamagnetic Susceptibilities, χm, of Inorganic Compounds

    Institute of Scientific and Technical Information of China (English)

    MU,Lai-Long; HE,Hong-Mei; FENG,Chang-Jun

    2007-01-01

    For predicting the molar diamagnetic susceptibilities of inorganic compounds, a novel connectivity index mG based on adjacency matrix of molecular graphs and ionic parameter gi was proposed. The gi is defined as gi= (ni0.5-0.91)4·xi0.5/Zi0.5, where Zi, ni, xi are the valence, the outer electronic shell primary quantum number, and the electronegativity of atom I respectively. The good QSPR models for the molar diamagnetic susceptibilities can be constructed from 0G and 1G by using multivariate linear regression (MLR) method and artificial neural network (NN) method. The correlation coefficient r, standard error, and average absolute deviation of the MLR model and NN model are 0.9868, 5.47 cgs, 4.33 cgs, 0.9885, 5.09 cgs and 4.06 cgs, respectively, for the 144 inorganic compounds. The cross-validation by using the leave-one-out method demonstrates that the MLR model is highly reliable from the point of view of statistics. The average absolute deviations of predicted values of the molar diamagnetic susceptibility of other 62 inorganic compounds (test set) are 4.72 cgs and 4.06 cgs for the MLR model and NN model. The results show that the current method is more effective than literature methods for estimating the molar diamagnetic susceptibility of an inorganic compound. Both MLR and NN methods can provide acceptable models for the prediction of the molar diamagnetic susceptibilities. The NN model for the molar diamagnetic susceptibilities appears more reliable than the MLR model.

  4. Insights into structure and activity of natural compound inhibitors of pneumolysin

    Science.gov (United States)

    Li, Hongen; Zhao, Xiaoran; Deng, Xuming; Wang, Jianfeng; Song, Meng; Niu, Xiaodi; Peng, Liping

    2017-01-01

    Pneumolysin is the one of the major virulence factor of the bacterium Streptococcus pneumoniae. In previous report, it is shown that β-sitosterol, a natural compound without antimicrobial activity, is a potent antagonist of pneumolysin. Here, two new pneumolysin natural compound inhibitors, with differential activity, were discovered via haemolysis assay. To explore the key factor of the conformation for the inhibition activity, the interactions between five natural compound inhibitors with differential activity and pneumolysin were reported using molecular modelling, the potential of mean force profiles. Interestingly, it is found that incorporation of the single bond (C22-C23-C24-C25) to replace the double bond (hydrocarbon sidechain) improved the anti-haemolytic activity. In view of the molecular modelling, binding of the five inhibitors to the conserved loop region (Val372, Leu460, and Tyr461) of the cholesterol binding sites led to stable complex systems, which was consistent with the result of β-sitosterol. Owing to the single bond (C22-C23-C24-C25), campesterol and brassicasterol could form strong interactions with Val372 and show higher anti-haemolytic activity, which indicated that the single bond (C22-C23-C24-C25) in inhibitors was required for the anti-haemolytic activity. Overall, the current molecular modelling work provides a starting point for the development of rational design and higher activity pneumolysin inhibitors. PMID:28165051

  5. Synthesis and Antiplatelet Activity of Antithrombotic Thiourea Compounds: Biological and Structure-Activity Relationship Studies

    Directory of Open Access Journals (Sweden)

    André Luiz Lourenço

    2015-04-01

    Full Text Available The incidence of hematological disorders has increased steadily in Western countries despite the advances in drug development. The high expression of the multi-resistance protein 4 in patients with transitory aspirin resistance, points to the importance of finding new molecules, including those that are not affected by these proteins. In this work, we describe the synthesis and biological evaluation of a series of N,N'-disubstituted thioureas derivatives using in vitro and in silico approaches. New designed compounds inhibit the arachidonic acid pathway in human platelets. The most active thioureas (compounds 3d, 3i, 3m and 3p displayed IC50 values ranging from 29 to 84 µM with direct influence over in vitro PGE2 and TXA2 formation. In silico evaluation of these compounds suggests that direct blockage of the tyrosyl-radical at the COX-1 active site is achieved by strong hydrophobic contacts as well as electrostatic interactions. A low toxicity profile of this series was observed through hemolytic, genotoxic and mutagenic assays. The most active thioureas were able to reduce both PGE2 and TXB2 production in human platelets, suggesting a direct inhibition of COX-1. These results reinforce their promising profile as lead antiplatelet agents for further in vivo experimental investigations.

  6. Electronic structure of RCo{sub x}Ge{sub 2} (R=Ce,Pr,Gd) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Penc, B.; Szytula, A.; Wawrzynska, E. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Winiarski, A. [A. Chelkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland)

    2006-01-01

    The electronic structure of the RCo{sub x}Ge{sub 2} (R=Ce,Pr,Gd) compounds with the orthorhombic crystal structure of CeNiSi{sub 2}-type was studied by X-ray photoemission spectroscopy. The valence bands of CeCo{sub 0.86}Ge{sub 2} and PrCo{sub 0.85}Ge{sub 2} compounds have the similar character. Near the Fermi level the broad peak corresponding to the Co 3d and R 4f and 5d6s states is observed. In the case of GdCo{sub 0.64}Ge{sub 2}, the strong intensity peak at 8.7 eV corresponding to Gd 4f states is observed. The analysis of the XPS spectra of Ce and Pr 3d{sub 5/2} and 3d{sub 3/2} in the Gunnarson-Schoenhammer model give the information on the hybridization of the f orbital with the conduction band. The hybridization energy equal 93 eV for R=Ce and 143 eV for R=Pr, respectively indicate stability of the shell in these compounds. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Magnetic structures and related properties of some rare-earth intermetallic compounds, RCu 2

    Science.gov (United States)

    Lebech, B.; Smetana, Z.; S̆íma, V.

    1987-12-01

    The magnetic structures and some relevant bulk magnetic properties of R(Cu, Ni) 2 (R = Tb, Tb zY 1- z, Dy, Ho, Er and Tm) are summarized. Basically, the magnetic structures are antiferromagnetically modulated with propagation vector {1}/{3}a∗. For R = Tb, Dy, Ho the a-axis anisotropy dominates and the structures are longitudinally modulated. For R = Tm, Er (probably) the b-axis anisotropy dominates and this results in transversely modulated structures. For R = Tb, Dy the structures are collinear, For R = Ho, Er, Tm (probably) an incommensurate modulation coexists with the commensurate a∗-axis modulation at the lowest temperature.

  8. Numerical Study on Flow and Heat Transfer Performance of Rectangular Heat Sink with Compound Heat Transfer Enhancement Structures

    Directory of Open Access Journals (Sweden)

    Di Zhang

    2014-04-01

    Full Text Available Modern gas turbine blade is operating at high temperature which requires abundant cooling. Considering both heat transfer rate and pumping power for internal passages, developing efficient cooling passages is of great importance. Ribbed channel has been proved as effective heat transfer enhancement technology for considerable heat transfer characteristics; however, the pressure loss is impressive. Dimple and protrusion are frequently considered as new heat transfer augmentation tools for their low friction loss in recent years. Numerical simulations are adopted to investigate the thermal performance of rectangular channel with compound heat transfer enhancement structures with ribs, dimples, and protrusions. Among all configurations, the nondimensional dimple/protrusion depths are 0.2. The results present the flow structures of all channel configurations. The Nu/Nu0 distributions of channel section are discussed for each case. The pressure penalty f/f0 and the thermal performance TP are also considered as important parameters for heat transfer enhancement. It can be concluded that the optimal structure of the compound heat transfer enhancement structure is rib + protrusion (D = 6 mm + dimple (D = 15 mm.

  9. Quantum mechanical treatment of As(3+)-thiol model compounds: implication for the core structure of As(III)-metallothionein.

    Science.gov (United States)

    Garla, Roobee; Kaur, Narinder; Bansal, Mohinder Pal; Garg, Mohan Lal; Mohanty, Biraja Prasad

    2017-03-01

    Exposure to inorganic arsenic (As) is one of the major health concerns in several regions around the world. Binding of As(III) with thiols is central to the mechanisms related to its toxicity, detoxification, and therapeutic effects. Due to its high thiol content, metallothionein (MT) is presumed to play an important role in case of arsenic toxicity. Consequences of these As-thiol interactions are not yet clear due to various difficulties in the characterization of arsenic bound proteins by spectroscopic techniques. Computational modeling can be a reliable approach in predicting the molecular structures of such complexes. This paper presents the results of a systematic study on different As(III)-thiol model compounds conducted by both ab initio and DFT methods with different Gaussian type basis sets. Proficiency of these theoretical methods has been evaluated in terms of bond lengths, bond angles, free energy, partial atomic charges, computational cost, and comparison with the experimental data. It has been demonstrated that the DFT-B3LYP/6-311+G(3df) functional offers better accuracy in predicting the structure and the UV absorption spectra of As(III)-thiol complexes. The results of the present study also helps in defining the boundaries for the core of arsenic bound MT so that quantum mechanical/molecular mechanical (QM/MM) methods can be employed to predict the structural and functional aspects of the protein. Graphical Abstract Optimized structural parameters of As(3+)-thiol model compounds.

  10. Inhibition of Human Transthyretin Aggregation by Non-Steroidal Anti-Inflammatory Compounds: A Structural and Thermodynamic Analysis

    Directory of Open Access Journals (Sweden)

    Luis Mauricio T. R. Lima

    2013-03-01

    Full Text Available Transthyretin (TTR is a homotetrameric protein that circulates in plasma and cerebral spinal fluid (CSF whose aggregation into amyloid fibrils has been associated with at least two different amyloid diseases: senile systemic amyloidosis (SSA and familial amyloid polyneuropathy (FAP. In SSA aggregates are composed of WT-TTR, while in FAP more than 100 already-described variants have been found in deposits. Until now, TTR-related diseases have been untreatable, although a new drug called Tafamidis has been approved only in Europe to specifically treat V30M patients. Thus, new strategies are still necessary to treat FAP caused by other variants of TTR. TTR has two channels in the dimer interface that bind to the hormone thyroxin and that have been used to accommodate anti-amyloidogenic compounds. These compounds stabilize the tetramers, rendering TTR less amyloidogenic. Here, we investigated the effects of three non-steroidal anti-inflammatory compounds—sulindac (SUL, indomethacin (IND and lumiracoxib (LUM—as tetramer stabilizers and aggregation inhibitors. WT-TTR and the very aggressive TTR variant L55P were used as models. These compounds were able to stabilize TTR against high hydrostatic pressure (HHP, increasing the ΔGf by several kcal. They were also effective in inhibiting WT-TTR and L55P acid- or HHP-induced aggregation; in particular, LUM and IND were very effective, inhibiting almost 100% of the aggregation of both proteins under certain conditions. The species formed when aggregation was performed in the presence of these compounds were much less toxic to cells in culture. The crystal structures of WT-TTR bound to the three compounds were solved at high resolution, allowing the identification of the relevant protein:drug interactions. We discuss here the ligand-binding features of LUM, IND and SUL to TTR, emphasizing the critical interactions that render the protein more stable and less amyloidogenic.

  11. Electronic band structure and specific features of Sm{sub 2}NiMnO{sub 6} compound: DFT calculation

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A.H. [Institute of complex systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Azam, Sikander, E-mail: sikander.physicst@gmail.com [Institute of complex systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic)

    2013-09-15

    The band structure, density of states, electronic charge density, Fermi surface and optical properties of Sm{sub 2}NiMnO{sub 6} compound have been investigated with the support of density functional theory (DFT). The atomic positions of Sm{sub 2}NiMnO{sub 6} compound were optimized by minimizing the forces acting on the atoms, using the full potential linear augmented plane wave method. We employed the local density approximation (LDA), generalized gradient approximation (GGA) and Engel–Vosko GGA (EVGGA) to treat the exchange correlation potential by solving Kohn–Sham equations. The calculation shows that the compound is metallic with strong hybridization near the Fermi energy level (E{sub F}). The calculated density of states at the E{sub F} is about 21.60, 24.52 and 26.21 states/eV, and the bare linear low-temperature electronic specific heat coefficient (γ) is found to be 3.74, 4.25 and 4.54 mJ/mol K{sup 2} for EVGGA, GGA and LDA, respectively. The Fermi surface is composed of two sheets. The bonding features of the compounds are analyzed using the electronic charge density in the (011) crystallographic plane. The dispersion of the optical constants was calculated and discussed. - Highlights: • The compound is metallic with strong hybridization near the Fermi energy. • The density of states at the Fermi energy is calculated. • The bare linear low-temperature electronic specific heat coefficient is obtained. • Fermi surface is composed of two sheets. • The bonding features are analyzed using the electronic charge density.

  12. Synthesis and Structures of [LCu(I)(SSi(i)Pr3)] (L = triphos, carbene) and Related Compounds.

    Science.gov (United States)

    Ferrara, Skylar J; Wang, Bo; Haas, Elaine; Wright LeBlanc, Karry; Mague, Joel T; Donahue, James P

    2016-09-19

    The mononuclear Cu(I) complexes [LCu(I)(SSi(i)Pr3)] (L = 1,1,1-tris(diphenylphosphinomethyl)ethane (triphos), 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes)) have been prepared by ligand displacement from [LCu(I)Cl] with (i)Pr3SiS(-). Both compounds are colorless, diamagnetic species and have been characterized structurally by X-ray crystallography. The compounds [(IMes)Cu(η(1)κ(S)-SC(O)CH3)] and [(triphos)Cu(η(1)κ(S)-SC(S)OCH3)] have been prepared in the context of synthesis aimed at [LCu(η(1)κ(S)-SCOS)] and [LCu(η(1)κ(S)-SCS2)] complexes, which are intended as synthons toward an analogue of the Mo(μ-OSCO)Cu intermediate proposed as occurring in the catalytic cycle of carbon monoxide dehydrogenase (CODH).

  13. Synthesis, Structural, and Antimicrobial Studies of Some New Coordination Compounds of Palladium(II with Azomethines Derived from Amino Acids

    Directory of Open Access Journals (Sweden)

    Monika Gupta

    2013-01-01

    Full Text Available Some new coordination compounds of palladium(II have been synthesized by the reaction of palladium(II acetate with azomethines in a 1 : 2 molar ratio using acetonitrile as a reaction medium. Azomethines used in these studies have been prepared by the condensation of 2-acetyl fluorene and 4-acetyl biphenyl with glycine, alanine, valine, and leucine in methanol. An attempt has been made to probe their bonding and structures on the basis of elemental analyses and IR, 1H, and 13C NMR spectral studies. Pd(II compounds have been found to be more active than their uncomplexed ligands as both of them were screened for antibacterial, antifungal, and insecticidal activities.

  14. Synthesis and crystal structure of a new organic compound: Bis(4,4'-diaminodiphenylmethane) (4,4'-diammoniodiphenylmethane) dichloride monohydrate

    Science.gov (United States)

    Wamani, W.; Belhouchet, M.; Mhiri, T.

    2013-01-01

    A new organic compound with the formula C39H46Cl2N6O was synthesized from aqueous solution of 4,4'-diaminodiphenylmethane and hydrochloric acid at room temperature. This compound crystallizes in the monoclinic space group C2: a = 25.6525(16), b = 5.7107(3), c = 13.7777(8) Å, β = 118.862(2)°, V = 1767.64(22) Å3 and Z = 2, giving D x = 1.288 g cm-3. The refinement converged to R 1 = 0.027 and wR 2 = 0.0649. The structural arrangement can be described as infinite layers parallel to bc plane. In these layers cations and non protonated molecules are linked with N-H...N hydrogen bonds building [C39H44N6]2+ organic clusters. These clusters, in turn, are linked by N-H...Cl and O-H...Cl hydrogen bonds.

  15. Structural, electronic and optical properties of hexagonal TaN compound

    Science.gov (United States)

    Chen, Zhongjun; Yan, Jungan; Kuang, Zhong; Chen, Taihong; Li, Dehua

    2016-01-01

    Structural and electronic properties of hexagonal Tantalum nitride (TaN) in CoSn and WC structures are studied using the first-principle calculations. Lattice constants and electronic band structures are in an excellent agreement with the available experimental and other theoretical values. TaN in both structures studied has a metallic nature and a strong hybridization of Ta 5d and N 2p are found from the spin density of states (DOS). Meanwhile, our LSDA+U calculations predicted a strong ferromagnetic state for CoSn-type structure and an obvious paramagnetic nature for WC-type structure. No phase transition are observed within cubic and hexagonal CoSn and WC structures under high pressures. Our results show WC-type TaN is the calculated ground-state structure among the three crystallographic structures studied under 120 GPa. Optical properties show that TaN in CoSn-type structure is a better dielectric material.

  16. Ionothermal synthesis and structural transformation targeted by ion exchange in metal-1,3,5-benzenetricarboxylate compounds

    Science.gov (United States)

    Xu, Qing-Qing; Liu, Bing; Xu, Ling; Jiao, Huan

    2017-03-01

    Ionothermal reactions of 1,3,5-benzenetricarboxylate acid (H3BTC) and Ni(NO3)2, Co(NO3)2 and Cu(NO3)2 gave two discrete 32-membered ring-like allomers, [M2(HBTC)2(NH2CONH2)2(H2O)4]·3H2O (M=Ni(1), Co(2)) and one layered [Cu2(BTC)Cl(H2O)4] (3). The weak interactions in 1 can be deconstructed to some degree in ion exchange by exploring the factors of divalent and trivalent metal species, metal concentration and soaking time, which are demonstrated by PXRD and N2 absorption. Cu2+ has the highest N2 adsorbance when soaking with 1, and 1 can keep structure stable when Cu2+ below 0.16 mol L-1 and the soaking time within 24d. As Cu2+ beyond 0.16 mol L-1 and the soaking time beyond 24d, the structure of compound 1 starts to transform with the crystal morphology from clear pale green to opaque blue. Ionothermal reactions of compound 1 with different Cu2+ amounts obtained Ni2+-Cu2+ hetero complexes, whose PXRD patterns are similar to that of 3 and EDS indicates Cu2+% increases with Cu2+ additions and close to 100% as Cu2+ being 1.6 mmol. It suggests that 3 is a controlled product and Cu2+ can transform discrete compound 1 into 2D compound 3.

  17. 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.

  18. Structural, electronic, optical and thermodynamic properties of cubic REGa{sub 3} (RE = Sc or Lu) compounds: Ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Murtaza, G., E-mail: murtaza@icp.edu.pk [Materials Modeling Laboratory, Department of Physics, Islamia College Peshawar (Pakistan); Gupta, S.K. [Department of Physics, Michigan Technological University, Houghton, MI 49931 (United States); Seddik, T. [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 Mascara (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique, Université de Mascara, 29000 Mascara (Algeria); Alahmed, Z.A. [Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia); Ahmed, R. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, UTM Skudai, 81310 Johor (Malaysia); Khachai, H. [Physics Department, Djillali Liabes University of Sidi Bel-Abbes (Algeria); Jha, P.K. [Department of Physics, Maharaja Krishnakumarsinhji Bhavnagar University, Bhavnagar 364001 (India); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

    2014-06-01

    Highlights: • REGa{sub 3} (RE = Sc or Lu) compounds are mechanical stabile. • Both ScGa{sub 3} and LuGa{sub 3} exhibit metallic behavior just like other REGa{sub 3} compounds. • Melting temperature T{sub m} (K) for ScGa{sub 3} and LuGa{sub 3} are 1244.2 and 1143.8. • High absorption observed in the visible energy region. • The present study would be helpful for future experimental/theoretical explorations. - Abstract: Structural, elastic, optoelectronic and thermodynamic properties of REGa{sub 3} (RE = Sc and Lu) compounds have been studied self consistently by employing state of the art full potential (FP) linearized (L) approach of augmented plane wave (APW) plus local orbitals method. Calculations were executed at the level of Perdew–Burke and Ernzerhof (PBE) parameterized generalized gradient approximation (GGA) for exchange correlation functional in addition to modified Becke–Johnson (mBJ) potential. Our obtained results of lattice parameters show reasonable agreement to the previously reported experimental and other theoretical studies. Analysis of the calculated band structure of ScGa{sub 3} and LuGa{sub 3} compounds demonstrates their metallic character. Moreover, a positive value of calculated Cauchy pressure, in addition to reflecting their ductile nature, endorses their metallic character as well. To understand optical behavior calculations related to the important optical parameters; real and imaginary parts of the dielectric function, reflectivity R(ω), refractive index n(ω) and electron energy-loss function L(ω) have also been performed. In the present work, thermodynamically properties are also investigated by employing lattice vibrations integrated in quasi harmonic Debye model. Obtained results of volume, heat capacity and Debye temperature as a function of temperature for both compounds, at different values of pressure, are found to be consistent. The calculated value of melting temperature for both compounds (ScGa{sub 3} and Lu

  19. Two new Cu{sup I} compounds with zwitterionic tetrazolate ligand: In situ synthesis, crystal structures, luminescence and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian-Yong; Xing, Yuan-Yuan; Wang, Qing-Wei [Shanghai Institute of Technology, Shanghai 200235 (China); Zhang, Na, E-mail: nzhang@sit.edu.cn [Shanghai Institute of Technology, Shanghai 200235 (China); Deng, Wei [Shanghai Institute of Technology, Shanghai 200235 (China); Gao, En-Qing [Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, Shanghai 200062 (China)

    2015-12-15

    Two 2D new Cu(I) coordination polymers, namely [Cu{sub 2}(mpTZ){sub 2}Br{sub 2}]·H{sub 2}O (1), and [Cu{sub 2}(mpTZ){sub 2}N{sub 3}]ClO{sub 4} (2) (mpTZ=N-methyl-4-pyridinium tetrazolate) have been synthesized under solvothermal conditions, in which the mpTZ ligands and Cu{sup I} ions were obtained through in situ [2+3] cycloaddition reaction and reduction reaction of Cu{sup II} salts, respectively. Both compounds have been structural characterized by single crystal X-ray diffraction, FT-IR, PXRD and EA. Compound 1 exhibits a 2D neutral coordination network, in which the Cu{sup I} ions are bridged by η{sub 3}−1, 2, 4-tetrazolate into 2D sheet. In compound 2, the Cu{sup I} ions are linked by azide (in µ{sub 3}−1, 1, 3 bridging mode) and tetrazolate (in η{sub 3}−1, 2, 3 bridging mode) anions into 2D positively charged sheet, extended along the bc plane. Both compounds 1 and 2 exhibit intense bluish green luminescence in the solid state. Photocatalytic performances of the two compounds for the degradation of methylene blue (MB) under visible light were also investigated and the MB degradation in the presence of 1 was nearly complete (99%) after 150 min. - Graphical abstract: Two Cu{sup I}CPs have been solvothermally synthesized through the in situ [2+3] cycloaddition and metal reduction reaction. Both compounds exhibit intense luminescence and high photocatalytic degradation under visible light. - Highlights: • Two new Cu{sup I}-based CPs are solvothermally synthesized through in situ [2+3] cycloaddition reaction and metal reduction reaction. • Both compounds exhibit strong luminescence and photocatalytic degradation of methylene blue (MB) under visible light. • The MB degradation in the presence of 1 is nearly complete (99%) after 150 min.

  20. Quantitative Structure – Antioxidant Activity Relationships of Flavonoid Compounds

    Directory of Open Access Journals (Sweden)

    Károly Héberger

    2004-12-01

    Full Text Available A quantitative structure – antioxidant activity relationship (QSAR study of 36 flavonoids was performed using the partial least squares projection of latent structures (PLS method. The chemical structures of the flavonoids have been characterized by constitutional descriptors, two-dimensional topological and connectivity indices. Our PLS model gave a proper description and a suitable prediction of the antioxidant activities of a diverse set of flavonoids having clustering tendency.

  1. Isolation and Structural Elucidation of Antiproliferative Compounds of Lipidic Fractions from White Shrimp Muscle (Litopenaeus vannamei)

    Science.gov (United States)

    López-Saiz, Carmen-María; Velázquez, Carlos; Hernández, Javier; Cinco-Moroyoqui, Francisco-Javier; Plascencia-Jatomea, Maribel; Robles-Sánchez, Maribel; Machi-Lara, Lorena; Burgos-Hernández, Armando

    2014-01-01

    Shrimp is one of the most popular seafood items worldwide, and has been reported as a source of chemopreventive compounds. In this study, shrimp lipids were separated by solvent partition and further fractionated by semi-preparative RP-HPLC and finally by open column chromatography in order to obtain isolated antiproliferative compounds. Antiproliferative activity was assessed by inhibition of M12.C3.F6 murine cell growth using the MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide) assay. The methanolic fraction showed the highest antiproliferative activity; this fraction was separated into 15 different sub-fractions (M1–M15). Fractions M8, M9, M10, M12, and M13 were antiproliferative at 100 µg/mL and they were further tested at lower concentrations. Fractions M12 and M13 exerted the highest growth inhibition with an IC50 of 19.5 ± 8.6 and 34.9 ± 7.3 µg/mL, respectively. Fraction M12 was further fractionated in three sub-fractions M12a, M12b, and M12c. Fraction M12a was identified as di-ethyl-hexyl-phthalate, fraction M12b as a triglyceride substituted by at least two fatty acids (predominantly oleic acid accompanied with eicosapentaenoic acid) and fraction M12c as another triglyceride substituted with eicosapentaenoic acid and saturated fatty acids. Bioactive triglyceride contained in M12c exerted the highest antiproliferative activity with an IC50 of 11.33 ± 5.6 µg/mL. Biological activity in shrimp had been previously attributed to astaxanthin; this study demonstrated that polyunsaturated fatty acids are the main compounds responsible for antiproliferative activity. PMID:25526568

  2. Phase equilibria and crystal structures of the compounds in the Pr-Ni-Sb system at 870 K

    Energy Technology Data Exchange (ETDEWEB)

    Chykhrij, S.I. [Department of Analytical Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodiya Str. 6, L' viv 79005 (Ukraine)]. E-mail: chykhrij@yahoo.com; Smetana, V.B. [Department of Analytical Chemistry, Ivan Franko National University of Lviv, Kyryla and Mefodiya Str. 6, L' viv 79005 (Ukraine)

    2005-09-01

    The isothermal section of the Pr-Ni-Sb system at 870 K over the whole concentration region has been built using X-ray analysis. At the temperature of the investigation three already known ternary antimonides PrNiSb, {approx}PrNiSb{sub 2} and {approx}PrNi{sub 2}Sb{sub 2} have been confirmed and three compounds {approx}Pr{sub 5}NiSb{sub 2}, PrNiSb{sub 3}, and PrNi{sub 2+x}Sb{sub 2-y} have been synthesized for the first time. The crystal structures of the obtained compounds belong to the following structure types: PrNiSb-ZrBeSi type, space group P6{sub 3}/mmc, a = 0.43838(2) nm, c = 0.81068(6) nm; PrNiSb{sub 3}-CeNiSb{sub 3} type, space group Pbcm, a = 1.2579(2) nm, b = 0.62051(8) nm, c = 1.8371(2) nm; {approx}Pr{sub 5}NiSb{sub 2}-structure related to Y{sub 5}Ni {sub x}Sb{sub 3-x}-type, space group Pnma, a = 1.2457(1) nm, b = 0.9159(1) nm, c = 0.8118(1) nm. The PrNi{sub 2}Sb{sub 2} compound crystallizes with an orthorhombic or monoclinic unit cell and a structure related to the tetragonal CaBe{sub 2}Ge{sub 2} type. The PrNi{sub 2+x}Sb{sub 2-y} antimonide has a small homogeneity region and crystallizes with a tetragonal unit cell (space group P4/nmm) and lattice parameters a = 0.431256(9) - 0.4319(1) nm, c = 0.99830(2) - 1.0092(3) nm. The existence of a considerable homogeneity region of the PrNi{sub 0.62-1.35}Sb{sub 2} compound is caused by a deficiency of Ni atoms or their excess compared to the initial structure of stoichiometric composition and a corresponding transition from the HfCuSi{sub 2} type to the CaBe{sub 2}Ge{sub 2} type with preservation of the unit cell symmetry (a 0.43539(4) - 0.44130(2) nm, c = 0.9653(1) - 0.97643(5) nm)

  3. Synthesis and structural analysis of a regular Cu-Mg-Al hydrotalcite-like compound

    OpenAIRE

    WU, Jian-Song; XIAO, Ying-Kai; Liu, Yu-ping; XU, Wan-Bang

    2011-01-01

    A fine-quality, regular Cu-Mg-Al hydrotalcite-like compound was synthesized via the glycothermal method using CuCl2 \\cdot 2H2O, MgCl2 \\cdot 6H2O, AlCl3 \\cdot 6H2O, and Na2CO3 as raw materials and sodium hydroxide as the precipitant. Hydrotalcite samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric-differential thermal analysis, and Brunauer-Emmett-Teller N2 surface ar...

  4. Ultrafast structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2.

    Science.gov (United States)

    Rettig, L; Mariager, S O; Ferrer, A; Grübel, S; Johnson, J A; Rittmann, J; Wolf, T; Johnson, S L; Ingold, G; Beaud, P; Staub, U

    2016-03-01

    Using femtosecond time-resolved hard x-ray diffraction, we investigate the structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2. The orthorhombic distortion analyzed by the transient splitting of the (1 0 3) Bragg reflection is suppressed on an initial timescale of 35 ps, which is much slower than the suppression of magnetic and nematic order. This observation demonstrates a transient state with persistent structural distortion and suppressed magnetic/nematic order which are strongly linked in thermal equilibrium. We suggest a way of quantifying the coupling between structural and nematic degrees of freedom based on the dynamics of the respective order parameters.

  5. Ultrafast structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2

    Directory of Open Access Journals (Sweden)

    L. Rettig

    2016-03-01

    Full Text Available Using femtosecond time-resolved hard x-ray diffraction, we investigate the structural dynamics of the orthorhombic distortion in the Fe-pnictide parent compound BaFe2As2. The orthorhombic distortion analyzed by the transient splitting of the (1 0 3 Bragg reflection is suppressed on an initial timescale of 35 ps, which is much slower than the suppression of magnetic and nematic order. This observation demonstrates a transient state with persistent structural distortion and suppressed magnetic/nematic order which are strongly linked in thermal equilibrium. We suggest a way of quantifying the coupling between structural and nematic degrees of freedom based on the dynamics of the respective order parameters.

  6. A theoretical study of molecular structure, optical properties and bond activation of energetic compound FOX-7 under intense electric fields

    Science.gov (United States)

    Tao, Zhiqiang; Wang, Xin; Wei, Yuan; Lv, Li; Wu, Deyin; Yang, Mingli

    2017-02-01

    Molecular structure, vibrational and electronic absorption spectra, chemical reactivity of energetic compound FOX-7, one of the most widely used explosives, were studied computationally in presence of an electrostatic field of 0.01-0.05 a.u. The Csbnd N bond, which usually triggers the decomposition of FOX-7, is shortened/elongated under a parallel/antiparallel field. The Csbnd N bond activation energy varies with the external electric field, decreasing remarkably with the field strength in regardless of the field direction. This is attributed to two aspects: the bond weakening by the field parallel to the Csbnd N bond and the stabilization effect on the transition-state structure by the field antiparallel to the bond. The variations in the structure and property of FOX-7 under the electric fields were further analyzed with its distributional polarizability, which is dependent on the charge transfer characteristics through the Csbnd N bond.

  7. Thermoluminescence and F centers of manganese doped NaCl and NaCl-CKl crystals exposed to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Somera, L.; Cruz Z, E.; Roman L, J. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Hernandez A, J. M.; Murrieta S, H., E-mail: ecruz@nucleares.unam.mx [UNAM, Instituto de Fisica, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2015-10-15

    Alkali halides crystals doped with rare earths or transition metals have been widely studied due to the luminescence properties. In particular, NaCl and KCl single crystals present thermally stimulated luminescence (Tl) after gamma irradiation. The NaCl and the NaCl KCl mixed crystal doped with manganese (MnCl{sub 2}) impurity were grown by using the Czochralski method. The emission characteristic of Mn{sup 2+} was observed at 543 nm. The crystals were exposed between 0.02 and 10 kGy gamma dose from {sup 60}Co irradiator. Optical absorption at room temperature shows the peaked band at 452 nm corresponding to the manganese impurity. The F bands, was ascribed to the electron trapped in the anion vacancy in the lattice, were obtained at 452 nm and 455 nm belonging to NaCl:Mn and NaCl KCl:Mn, respectively. The F band increases as the doses increase and it was bleaching by the UV light at 470 nm. The glow curves of the samples show the first glow peak between 92-103 degrees C, while the second main peak was observed at 183 degrees C for the undoped NaCl and at 148 and 165 degrees C for the NaCl:Mn and NaCl-KCl:Mn, respectively. The main peak was slowly bleaching when the irradiated sample was illuminated with F (470 nm) light. Optical bleaching confirms that the F center has an important participation in the thermoluminescent response. The glow curves structure from the thermal bleaching suggests the participation of different kind of traps. Also, the kinetics parameters such as activation energy (E), frequency factor (s) and the kinetic order (b) were investigated. (Author)

  8. EVALUATION OF STRUCTURAL AND BIOCHEMICAL ALTERATIONS IN ASPERGILLUS TERREUS BY THE ACTION OF ANTIFUNGAL ANTIBIOTIC COMPOUND FROM STREPTOMYCES SP. JF714876

    Directory of Open Access Journals (Sweden)

    Babanagare Shankaravva S.

    2011-11-01

    Full Text Available Antifungal compound obtained by Streptomyces sp. JF714876 was examined for its effect on morphological and biochemical alteration in Aspergillus terreus. Microscopic observation revealed swelling of hyphae with deformation and distortion in mycelial structure in presence of moderate concentration of antifungal compound. At high concentration, the compound exhibited fungicidal action. Antifungal treated Aspergillus terreus showed changes in its biochemical content such as, protein, carbohydrates, peroxidase, catalase and amylase as compared to untreated.

  9. WNK kinases regulate thiazide-sensitive Na-Cl cotransport.

    Science.gov (United States)

    Yang, Chao-Ling; Angell, Jordan; Mitchell, Rose; Ellison, David H

    2003-04-01

    Pseudohypoaldosteronism type II (PHAII) is an autosomal dominant disorder of hyperkalemia and hypertension. Mutations in two members of the WNK kinase family, WNK1 and WNK4, cause the disease. WNK1 mutations are believed to increase WNK1 expression; the effect of WNK4 mutations remains unknown. The clinical phenotype of PHAII is opposite to Gitelman syndrome, a disease caused by dysfunction of the thiazide-sensitive Na-Cl cotransporter. We tested the hypothesis that WNK kinases regulate the mammalian thiazide-sensitive Na-Cl cotransporter (NCC). Mouse WNK4 was cloned and expressed in Xenopus oocytes with or without NCC. Coexpression with WNK4 suppressed NCC activity by more than 85%. This effect did not result from defects in NCC synthesis or processing, but was associated with an 85% reduction in NCC abundance at the plasma membrane. Unlike WNK4, WNK1 did not affect NCC activity directly. WNK1, however, completely prevented WNK4 inhibition of NCC. Some WNK4 mutations that cause PHAII retained NCC-inhibiting activity, but the Q562E WNK4 demonstrated diminished activity, suggesting that some PHAII mutations lead to loss of NCC inhibition. Gain-of-function WNK1 mutations would be expected to inhibit WNK4 activity, thereby activating NCC, contributing to the PHAII phenotype. Together, these results identify WNK kinases as a previously unrecognized sodium regulatory pathway of the distal nephron. This pathway likely contributes to normal and pathological blood pressure homeostasis.

  10. Paleothermometry of NaCl as evidenced from thermoluminescence data

    Energy Technology Data Exchange (ETDEWEB)

    Gartia, R.K. [Physics Department, Manipur University, Imphal 795003 (India)], E-mail: rkgartia02@yahoo.in

    2009-09-01

    The firing temperature of ancient ceramic artifacts, i.e. the paleothermometry of these materials has been estimated by various techniques including thermoluminescence (TL) and, more recently, Optically Stimulated Luminescence (OSL) where the OSL response of quartz to firing temperature is used. In this work we report the paleothermometry of sodium chloride (NaCl) by studying the TL response of the material as a function of annealing temperatures in the range of 100-500 deg. C. Annealing/measurement has been done in a commercial TL/OSL reader (Model No. Riso TL/OSL reader TL-DA-15) in a nitrogen atmosphere. Sodium chloride (NaCl) has been selected as the candidate to test the feasibility of the technique since in this system TL peaks are correlated with the thermal annealing of F-centers unlike the case of quartz where a one to one correlation with all the glow peaks and thermal annealing of defects has not been possible.

  11. Sodium reduction in margarine using NaCl substitutes

    Directory of Open Access Journals (Sweden)

    CARLA GONÇALVES

    2017-08-01

    Full Text Available ABSTRACT Sodium chloride is traditionally used as a food additive in food processing. However, because of its high sodium content, NaCl has been associated with chronic diseases. Margarine is a popular product that is used in several preparations, but it includes high sodium content; therefore, it is among the products whose sodium content should be reduced. Thus, the objective of this study was to produce margarines with reduced sodium content prepared using a salt mixture. The following 4 margarine formulations were prepared: Formulation A (control - 0% sodium reduction, Formulation B (20.8% less sodium, Formulation C (33.0% less sodium and Formulation D (47.4% less sodium. The low sodium formulations were produced using a salt mixture consisting of NaCl, KCl, and monosodium glutamate at different concentrations. The margarines were evaluated using an acceptance test and descriptive tests: time-intensity and temporal dominance of sensations. The mixture used is a good alternative for preparing low sodium margarine because the low sodium formulations feature equal salinity and do not produce a strange or bad taste. Furthermore, it may be possible to prepare margarines with up to 47.4% less sodium and that are acceptable to consumers.

  12. Sodium reduction in margarine using NaCl substitutes.

    Science.gov (United States)

    Gonçalves, Carla; Rodrigues, Jéssica; Júnior, Heraldo; Carneiro, João; Freire, Tassyana; Freire, Luísa

    2017-08-17

    Sodium chloride is traditionally used as a food additive in food processing. However, because of its high sodium content, NaCl has been associated with chronic diseases. Margarine is a popular product that is used in several preparations, but it includes high sodium content; therefore, it is among the products whose sodium content should be reduced. Thus, the objective of this study was to produce margarines with reduced sodium content prepared using a salt mixture. The following 4 margarine formulations were prepared: Formulation A (control - 0% sodium reduction), Formulation B (20.8% less sodium), Formulation C (33.0% less sodium) and Formulation D (47.4% less sodium). The low sodium formulations were produced using a salt mixture consisting of NaCl, KCl, and monosodium glutamate at different concentrations. The margarines were evaluated using an acceptance test and descriptive tests: time-intensity and temporal dominance of sensations. The mixture used is a good alternative for preparing low sodium margarine because the low sodium formulations feature equal salinity and do not produce a strange or bad taste. Furthermore, it may be possible to prepare margarines with up to 47.4% less sodium and that are acceptable to consumers.

  13. Two 8-Hydroxyquinolinate Based Supramolecular Coordination Compounds: Synthesis, Structures and Spectral Properties

    Directory of Open Access Journals (Sweden)

    Chengfeng Zhu

    2017-03-01

    Full Text Available Two new Cr(III complexes based on 2-substituted 8-hydroxyquinoline ligands, namely [Cr(L13] (1, (HL1=(E-2-[2-(4-nitro-phenyl-vinyl]-8-hydroxy-quinoline and [Cr(L23] (2, (HL2=(E-2-[2-(4-chloro-phenylvinyl]-8-hydroxy-quinoline, were prepared by a facile hydrothermal method and characterized thoroughly by single crystal X-ray diffraction, powder X-ray diffraction, FTIR, TGA, ESI-MS, UV-Visible absorption spectra and fluorescence emission spectra. Single crystal X-ray diffraction analyses showed that the two compounds featured 3D supramolecular architectures constructed from noncovalent interactions, such as π···π stacking, C-H···π, C-H···O, C-Cl···π, C-H···Cl interactions. The thermogravimetric analysis and ESI-MS study of compounds 1 and 2 suggested that the Cr(III complexes possessed good stability both in solid and solution. In addition, the ultraviolet and fluorescence response of the HL1 and HL2 shown marked changes upon their complexation with Cr(III ion, which indicated that the two 8-hydroxyquinolinate based ligand are promising heavy metal chelating agent for Cr3+.

  14. Structural, magnetic and electronic transport studies of RAgSn2 compounds (R = Y, Tb, Dy, Ho and Er) with Cu3Au-type

    Indian Academy of Sciences (India)

    L Romaka; V V Romaka; I Lototska; A Szytula; B Kuzhel; A Zarzycki; E K Hlil; D Fruchart

    2013-12-01

    RAgSn2 compounds, where R = Y, Tb, Dy, Ho and Er, were synthesized by arc-melting and subsequent annealing at 870 K. The formation of cubic phases with Cu3Au-type structure (space group $\\bar{3}$) was studied. Magnetic property measurements showed that in paramagnetic state, the compounds with magnetic rareearth atoms are Curie–Weiss paramagnets and order antiferromagnetically at low temperatures. YAgSn2 is a Pauli paramagnet in 100–300 K temperature range. The electrical properties of RAgSn2 compounds were investigated by means of electrical resistivity and Seebeck coefficient measurements in 4.2–300 K temperature range. All investigated compounds exhibit metallic type of conductivity. Electronic structure calculations based on full potential linearized augmented plane wave (FLAPW)method is also carried out to probe themagnetic and electronic structures of RAgSn2 compounds. Comparisons between experimental data and calculations are discussed.

  15. Geometrically frustrated magnetic structures of the heavy-fermion compound CePdAl studied by powder neutron diffraction

    Science.gov (United States)

    Dönni, A.; Ehlers, G.; Maletta, H.; Fischer, P.; Kitazawa, H.; Zolliker, M.

    1996-12-01

    The heavy-fermion compound CePdAl with ZrNiAl-type crystal structure (hexagonal space group 0953-8984/8/50/043/img8) was investigated by powder neutron diffraction. The triangular coordination symmetry of magnetic Ce atoms on site 3f gives rise to geometrical frustration. CePdAl orders below 0953-8984/8/50/043/img9 with an incommensurate antiferromagnetic propagation vector 0953-8984/8/50/043/img10, and a longitudinal sine-wave (LSW) modulated spin arrangement. Magnetically ordered moments at Ce(1) and Ce(3) coexist with frustrated disordered moments at Ce(2). The experimentally determined magnetic structure is in agreement with group theoretical symmetry analysis considerations, calculated by the program MODY, which confirm that for Ce(2) an ordered magnetic moment parallel to the magnetically easy c-axis is forbidden by symmetry. Further low-temperature experiments give evidence for a second magnetic phase transition in CePdAl between 0.6 and 1.3 K. Magnetic structures of CePdAl are compared with those of the isostructural compound TbNiAl, where a non-zero ordered magnetic moment for the geometrically frustrated Tb(2) atoms is allowed by symmetry.

  16. Magnetic properties and magnetic structures of RCo{sub x}Sn{sub 2} (R=Gd-Er) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gil, A.; Penc, B.; Wawrzynska, E.; Hernandez-Velasco, J.; Szytula, A.; Zygmunt, A

    2004-02-25

    Magnetic properties of RCo{sub x}Sn{sub 2} (R=Gd-Er) stannides, determined on the basis of magnetic and powder diffraction data, are reported. The compounds crystallize in the orthorhombic CeNiSn{sub 2}-type structure. Magnetic and neutron diffraction measurements (the latter for R=Tb and Ho) show that all the compounds are antiferromagnets with Neel temperatures of 16.5 K (R=Gd), 18.8 K (R=Tb), 7 K (R=Dy), 5.6 K (R=Ho) and 4.5 K (R=Er). The neutron diffraction data indicate the presence of collinear magnetic structures described by the propagation vector k=(0, 0, ((1)/(2))) for R=Tb and k=(((1)/(2)), ((1)/(2)), 0) for R=Ho. The determined magnetic structures of RCo{sub x}Sn{sub 2} (R=Tb, Ho) are similar to those observed in the isostructural RNi{sub x}Sn{sub 2}.

  17. Synthesis, Structure and Biological Activities of Novel Triazole Compounds Containing 4,6-Dimethyl-pyrimidin-2-ylthio Group

    Institute of Scientific and Technical Information of China (English)

    XU, Liang-Zhong(许良忠); JIAN, Fang-Fang(建方方); SHI, Jian-Gang(时建刚); LI, Lin(李琳)

    2004-01-01

    Four compounds were prepared by reacting 4,6-dimethyl-2-mercaptopyrimidine with α-bromo-α-(1,2,4-triazol-1-yl)-substituted acetylbenzene. Their structures were identified by means of elemental analysis, IR, and 1H NMR spectra. The single crystal structure of 2- [ 1 -(1,2,4-triazol- 1-yl)- 1-p-methoxyphenylcarbonylmethylthio] -4,6-dimethyl-pyrimidine was also determined. It crystallizes in monoclinic system, space group P21/c, a=0.8016(2) nm, b=1.2462(3) nm, c= 1.7824(4) nm,β=99.89(3)°, Z=4, V=1.7540(7) nm3, Dc=1.346 g/cm3, μ=0.205 mm-1, F(000)=744, final R1=0.0452. There is obviously potentially weak C-H…N intermolecular interaction between the molecules in the crystal lattice, which stabilizes the crystal structure. The result of the biological test showed that the four compounds all have some fungicidal and plant growth regulating activities.

  18. Correlation between magnetostriction and magnetic structure in pseudobinary compounds Tb(Co1-xFex)2

    Science.gov (United States)

    Wang, Yue; Ma, Tianyu; Wu, Chen; Yan, Mi; Zhang, Changsheng; Chen, Xiping; Sun, Guangai; Yang, Sen; Wang, Yu; Chang, Tieyan; Zhou, Chao; Liao, Xiaoqi; Zheng, Xinqi

    2017-07-01

    Giant low-field magnetostriction has been achieved in pseudobinary Laves phase compounds RR'T2 (R and R': rare earth elements; T: transition metal elements) around the ferromagnetic - ferromagnetic (ferro.-ferro.) transition temperature. Evolution of the magnetic structure across such transition requires comprehensive investigation. In this work, pseudobinary system Tb(Co1-xFex)2 is selected to investigate the evolution of local magnetic moment, for which two end terminals TbCo2 and TbFe2 possess the rhombohedral (R) structure at the ferromagnetic state but with different magnetic ordering temperatures (TC). Magnetometry measurements reveal that a composition independent ferromagnetic - ferromagnetic transition occurs at ˜100 K despite the increased Curie temperature TC with raised Fe concentration in the Tb(Co1-xFex)2. Synchrotron XRD data reveal that both the lattice parameter and the lattice strain along the direction are abnormally temperature dependent, accompanied with experimentally observed magnetostriction abnormality at 100 K. In-situ neutron powder diffraction (NPD) results show that the local magnetic moments of T2 (9e site) atoms are also abnormally temperature dependent, which is larger at 100 K than that at a lower temperature 50 K. Such findings indicate close correlations between the magnetic structure and the magnetostrictive effect in the pseudobinary RT2 compounds.

  19. Correlation between magnetostriction and magnetic structure in pseudobinary compounds Tb(Co1-xFex2

    Directory of Open Access Journals (Sweden)

    Yue Wang

    2017-07-01

    Full Text Available Giant low-field magnetostriction has been achieved in pseudobinary Laves phase compounds RR’T2 (R and R’: rare earth elements; T: transition metal elements around the ferromagnetic - ferromagnetic (ferro.-ferro. transition temperature. Evolution of the magnetic structure across such transition requires comprehensive investigation. In this work, pseudobinary system Tb(Co1-xFex2 is selected to investigate the evolution of local magnetic moment, for which two end terminals TbCo2 and TbFe2 possess the rhombohedral (R structure at the ferromagnetic state but with different magnetic ordering temperatures (TC. Magnetometry measurements reveal that a composition independent ferromagnetic - ferromagnetic transition occurs at ∼100 K despite the increased Curie temperature TC with raised Fe concentration in the Tb(Co1-xFex2. Synchrotron XRD data reveal that both the lattice parameter and the lattice strain along the direction are abnormally temperature dependent, accompanied with experimentally observed magnetostriction abnormality at 100 K. In-situ neutron powder diffraction (NPD results show that the local magnetic moments of T2 (9e site atoms are also abnormally temperature dependent, which is larger at 100 K than that at a lower temperature 50 K. Such findings indicate close correlations between the magnetic structure and the magnetostrictive effect in the pseudobinary RT2 compounds.

  20. Crystal structure and physical properties of the new ternary compound MgNi{sub 7}B{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Liao, C.Z. [Key Laboratory of Nonferrous Metals and New Processing Technology of Materials, Ministry of Education, Guangxi University, Nanning Guangxi 530004 (China); National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China); Dong, C., E-mail: chengdon@iphy.ac.c [National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China); Zeng, L.M. [Key Laboratory of Nonferrous Metals and New Processing Technology of Materials, Ministry of Education, Guangxi University, Nanning Guangxi 530004 (China); He, B. [National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China); Luzhou Medical College, Luzhou, Sichuan 646000 (China); Cao, W.H. [Key Laboratory of Nonferrous Metals and New Processing Technology of Materials, Ministry of Education, Guangxi University, Nanning Guangxi 530004 (China); National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China); Yang, L.H. [National Laboratory for Superconductivity, Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2010-03-18

    A new compound MgNi{sub 7}B{sub 3} in the Mg-Ni-B ternary system was prepared by solid state reaction and its crystal structure was determined using X-ray powder diffraction data. The MgNi{sub 7}B{sub 3} compound crystallizes with ErNi{sub 7}B{sub 3} structure type (space group I4{sub 1}/amd, a = 7.4877(2) A, c = 15.4879(4) A, Z = 8.), and the Rietveld refinement of the crystal structure was performed which gave R{sub wp} = 7.02%, R{sub p} = 4.96%. The MgNi{sub 7}B{sub 3} sample was characterized by magnetization and electric resistivity measurements. MgNi{sub 7}B{sub 3} exhibits metallic behavior in the temperature range from 5 to 300 K and shows spin-glass-like behavior at low temperature with the spin freezing temperature (T{sub f}) around 13 K.