Microstructural and compositional Evolution of Compound Layers during Gaseous Nitrocarburizing

DEFF Research Database (Denmark)

Du, Hong; Somers, Marcel A.J.; Ågren, John

2000-01-01

Compound layers developed at 848 K during gaseous nitrocarburizing of iron and iron-carbon specimens were investigated for several combinations of N and C activities imposed at the specimen surface by gas mixtures of NH3, N2, CO2 and CO. The microstructural evolution of the compound layer was stu...

Growth, spectral, optical, laser damage threshold and DFT investigations on 2-amino 4-methyl pyridinium 4-methoxy benzoate (2A4MP4MB): A potential organic third order nonlinear optical material for optoelectronic applications

Science.gov (United States)

Krishnakumar, M.; Karthick, S.; Thirupugalmani, K.; Babu, B.; Vinitha, G.

2018-05-01

In present investigation, single crystals of organic charge transfer complex, 2-amino-4-methyl pyridinium-4-methoxy benzoate (2A4MP4MB) was grown by controlled slow evaporation solution growth technique using methanol as a solvent at room temperature. Single crystal XRD analysis confirmed the crystal system and lattice parameters of 2A4MP4MB. The crystalline nature, presence of various vibrational modes and other chemical bonds in the compound have been recognized and confirmed by powder X-ray diffraction, FT-IR and FT-Raman spectroscopic techniques respectively. The presence of various proton and carbon positions in title compound was confirmed using 1H NMR and 13C NMR spectral studies. The wide optical operating window and cut-off wavelength were identified and band gap value of the title compound was calculated using UV-vis-NIR study. The specific heat capacity (cp) values of the title compound, 1.712 J g-1·K-1 at 300 K and 13.6 J g-1 K-1 at 433 K (melting point) were measured using Modulated Differential Scanning Calorimetric studies (MDSC). From Z-scan study, nonlinear refractive index (n2), nonlinear absorption (β) and third order nonlinear susceptibility (χ(3)) values were determined. The self-defocusing effect and saturable absorption behavior of the material were utilized to exhibit the optical limiting action at λ = 532 nm by employing the same continuous wave (cw) Nd: YAG laser source. The laser damage threshold (LDT) study of title compound was carried out using Nd: YAG laser of 532 nm wavelength. The Vickers' micro hardness test was carried out at room temperature and obtained results were investigated using classical Meyer's law. In addition, DFT calculations were carried out for the first time for this compound. These characterization studies performed on the title compound planned to probe the valuable and safe region of optical, thermal and mechanical properties to improve efficacy of 2A4MP4MB single crystals in optoelectronic device

New metal-organic frameworks of [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La, Ce) and [Ce2(C2O4)(C6H6O7)2] . 4H2O

International Nuclear Information System (INIS)

Weng Shengfeng; Wang, Yun-Hsin; Lee, Chi-Shen

2012-01-01

Two novel materials, [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2), with a metal-organic framework (MOF) were prepared with hydrothermal reactions and characterized with photoluminescence, magnetic susceptibility, thermogravimetric analysis and X-ray powder diffraction in situ. The crystal structures were determined by single-crystal X-ray diffraction. Compound 1 crystallized in triclinic space group P1-bar (No. 2); compound 2 crystallized in monoclinic space group P2 1 /c (No. 14). The structure of 1 is built from a 1D MOF, composed of deprotonated citric ligands of three kinds. Compound 2 contains a 2D MOF structure consisting of citrate and oxalate ligands; the oxalate ligand arose from the decomposition in situ of citric acid in the presence of Cu II ions. Photoluminescence spectra of compounds 1b and 2 revealed transitions between the 5d 1 excited state and two levels of the 4f 1 ground state ( 2 F 5/2 and 2 F 7/2 ). Compounds 1b and 2 containing Ce III ion exhibit a paramagnetic property with weak antiferromagnetic interactions between the two adjacent magnetic centers. - Graphical Abstract: [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2)—with 1D and 2D structures were synthesized and characterized. Highlights: ► Two MOF – [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2) – with 1D and 2D structures. ► The adjacent chains of the 1D framework were correlated with each other through an oxalate ligand to form a 2D layer structure. ► The source of the oxalate ligand was the decomposition in situ of citric acid oxidized in the presence of Cu II ions.

Characterization, electrical transport and magnetic properties of the rare earth misfit layer compounds (TbS)(1.21)NbS2, (TbS)(1.20)TaS2, (DyS)(1.22)NbS2 and (DyS)(1.21)TaS2

NARCIS (Netherlands)

Zhou, W.Y.; Meetsma, A.; deBoer, J.L.; Wiegers, G.A

1996-01-01

X-ray powder and single-crystal X-ray diffraction of the title compounds showed that they are planar intergrowth compounds, built of alternating sandwiches TS2 (T=Nb, Ta) and double layers LnS (Ln=Tb, Dy), present in three orientational variants related by rotations of 120 degrees around the c axis

Novel 2D or 3D alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand

Science.gov (United States)

Du, Zi-Yi; Wen, He-Rui; Xie, Yong-Rong

2008-11-01

Three novel alkaline-earth metal sulfonate-phosphonates based on [O 3S-C 2H 4-PO 3H] 2- ligand, namely, [Ca(O 3SC 2H 4PO 3H)(H 2O) 2] ( 1), [Sr(O 3SC 2H 4PO 3H)] ( 2) and [Ba 2(O 3SC 2H 4PO 3H) 2] ( 3), have been synthesized by hydrothermal reactions. They represent the first structurally characterized alkaline-earth metal complexes of phosphonic acid attached with a sulfonate group. The structure of compound 1 features a 2D layer based on 1D chains of [Ca 2(PO 3) 2] bridged by -CH 2-CH 2-SO 3- groups. Compounds 2 and 3 show pillar-layer architecture based on two different inorganic layers linked by -CH 2-CH 2- groups. The inorganic layer in compound 2 features a 1D chain of edge-sharing SrO 8 polyhedra whereas that in compound 3 features an edge-sharing Ba 2O 14 di-polyhedral unit which is further corner-shared with four neighboring ones. The [O 3S-C 2H 4-PO 3H] 2- ligand shows diverse coordination modes in the three alkaline-earth metal sulfonate-phosphonates.

Structure of superhard tungsten tetraboride: A missing link between MB2 and MB12 higher borides

Science.gov (United States)

Lech, Andrew T.; Turner, Christopher L.; Mohammadi, Reza; Tolbert, Sarah H.; Kaner, Richard B.

2015-01-01

Superhard metals are of interest as possible replacements with enhanced properties over the metal carbides commonly used in cutting, drilling, and wear-resistant tooling. Of the superhard metals, the highest boride of tungsten—often referred to as WB4 and sometimes as W1–xB3—is one of the most promising candidates. The structure of this boride, however, has never been fully resolved, despite the fact that it was discovered in 1961—a fact that severely limits our understanding of its structure–property relationships and has generated increasing controversy in the literature. Here, we present a new crystallographic model of this compound based on refinement against time-of-flight neutron diffraction data. Contrary to previous X-ray–only structural refinements, there is strong evidence for the presence of interstitial arrangements of boron atoms and polyhedral bonding. The formation of these polyhedra—slightly distorted boron cuboctahedra—appears to be dependent upon the defective nature of the tungsten-deficient metal sublattice. This previously unidentified structure type has an intermediary relationship between MB2 and MB12 type boride polymorphs. Manipulation of the fractionally occupied metal and boron sites may provide insight for the rational design of new superhard metals. PMID:25733870

Syntheses, structures, photoluminescence and photocatalysis of 2D layered lanthanide-carboxylates with 2, 2′-dithiodibenzoic acid

Energy Technology Data Exchange (ETDEWEB)

Ding, Ling; Zhong, Jie-Cen; Qiu, Xing-Tai; Sun, Yan-Qiong, E-mail: sunyq@fzu.edu.cn; Chen, Yi-Ping

2017-02-15

Two series of lanthanide-carboxylates, [Ln(2,2′-dtba)(2,2′-Hdtba)(EtOH)]{sub n} (I:Ln=Eu(1a), Dy(1b)) and [Ln(2,2′-dtba)(2,2′-Hdtba)(4,4′-bpy){sub 0.5}]{sub n} (II:Ln=Eu(2a), Dy(2b), Tb(2c) 2,2′-H{sub 2}dtba=2,2′-dithiodibenzoic acid, 4,4′-bpy=4,4′-bipyridine) have been synthesized under hydrothermal conditions. Interestingly, the H{sub 2}dtba organic ligand was generated by in situ S–S reaction of 2-mercaptobenzoic acid. Compounds I and II possess different 2D layered structures based on similar 1D [Ln(2,2′-dtba)]{sup +} chains. Photoluminescence studies reveal that compounds I and II exhibit strong lanthanide characteristic emission bands. Remarkably, Compounds 1b and 2a both exhibit good photocatalytic activity for degradation of Rhodamine-B (Rh-B) under the simulated sunlight irradiation. - Graphical abstract: Two series of lanthanide-carboxylates have been in situ synthesized under hydrothermal conditions. The lanthanide-carboxylates exhibit strong lanthanide characteristic emission bands and good photocatalytic activity for degradation of Rhodamine-B. - Highlights: • 2D layered lanthanide-carboxylates with 2,2′-dithiodibenzoic acid. • In situ S–S reaction of 2-mercaptobenzoic acid under hydrothermal condition. • The Emission spectra of I and II exhibit the characteristic transition of lanthanide ions. • Compounds 1b and 2a exhibit good photocatalytic activity for degradation of Rhodamine-B.

Decolorization of methylene blue in layered manganese oxide suspension with H2O2

International Nuclear Information System (INIS)

Zhang Lili; Nie Yulun; Hu Chun; Hu Xuexiang

2011-01-01

Highlights: → Layered birnessite-type manganese oxides exhibited a well-crystallized octahedral layer (OL) structure with β-MnOOH, α-MnOOH and γ-Mn 3 O 4 . → The catalyst was highly effective for the decolorization and degradation of methylene blue in the presence of H 2 O 2 at neutral pH. → The 1 O 2 and O 2 · - were the main reactive oxygen species in the reaction. - Abstract: Layered birnessite-type manganese oxides (Na-OL-1) were prepared via a redox reaction involving MnO 4 - and Mn 2+ under markedly alkaline conditions. According to the XRD analysis, the resulting material exhibited a well-crystallized octahedral layer (OL) structure with several different phases, including β-MnOOH, α-MnOOH and γ-Mn 3 O 4 . The catalyst was highly effective for the decolorization and degradation of methylene blue (MB) in the presence of H 2 O 2 at neutral pH. The tested MB was completely decolorized in Na-OL-1 suspension by the fraction dosing of H 2 O 2 (556.5 mM at the beginning and then 183.8 mM at 40 min). Based on the studies of electron spin resonance and the effect of radical scavengers, the 1 O 2 and O 2 · - were the main reactive oxygen species (ROS) in the reaction. It was found that both oxygen and ROS were generated from the decomposition of H 2 O 2 in Na-OL-1 suspension, wherein the decomposition pathways were proposed. The generation of H 2 O 2 in Na-OL-1 suspension at air atmosphere indicated that the existence of multivalent manganese oxides greatly enhanced the interfacial electron transfer, leading to the high activity of Na-OL-1.

Nd2(SeO3)2(SeO4) . 2H2O - a mixed-valence compound containing selenium in the oxidation states +IV and +VI

International Nuclear Information System (INIS)

Berdonosov, P.S.; Dityat'yev, O.A.; Dolgikh, V.A.; Schmidt, P.; Ruck, Michael; Lightfoot, P.

2004-01-01

Pale pink crystals of Nd 2 (SeO 3 ) 2 (SeO 4 ) . 2H 2 O were synthesized under hydrothermal conditions from H 2 SeO 3 and Nd 2 O 3 at about 200 C. X-ray diffraction on powder and single-crystals revealed that the compound crystallizes with the monoclinic space group C 2/c (a = 12.276(1) A, b = 7.0783(5) A, c = 13.329(1) A, β = 104.276(7) ). The crystal structure of Nd 2 (SeO 3 ) 2 (SeO 4 ) . 2H 2 O is an ordered variant of the corresponding erbium compound. Eight oxygen atoms coordinate the Nd III atom in the shape of a bi-capped trigonal prism. The oxygen atoms are part of pyramidal (Se IV O 3 ) 2- groups, (Se VI O 4 ) 2- tetrahedra and water molecules. The [NdO 8 ] polyhedra share edges to form chains oriented along [010]. The selenate ions link these chains into layers parallel to (001). The layers are interconnected by the selenite ions into a three-dimensional framework. The dehydration of Nd 2 (SeO 3 ) 2 (SeO 4 ) . 2H 2 O starts at 260 C. The thermal decomposition into Nd 2 SeO 5 , SeO 2 and O 2 at 680 C is followed by further loss of SeO 2 leaving cubic Nd 2 O 3 . (Abstract Copyright [2004], Wiley Periodicals, Inc.) [de

Model Research On Synthesis Of Al2O3-C Layers By MOCVD

Directory of Open Access Journals (Sweden)

Sawka A.

2015-06-01

Full Text Available These are model studies whose aim is to obtain information that would allow development of new technology for synthesizing monolayers of Al2O3-C with adjusted microstructure on cemented carbides. The Al2O3-C layer will constitute an intermediate layer on which the outer layer of Al2O3 without carbon is synthesized. The purpose of the intermediate layer is to block the cobalt diffusion to the synthesized outer layer of Al2O3 and to stop the diffusion of air oxygen to the substrate during the synthesis of the outer layer. This layer should be thin, continuous, dense and uniform in thickness.

In-situ fabrication of MoSi2/SiC–Mo2C gradient anti-oxidation coating on Mo substrate and the crucial effect of Mo2C barrier layer at high temperature

International Nuclear Information System (INIS)

Liu, Jun; Gong, Qianming; Shao, Yang; Zhuang, Daming; Liang, Ji

2014-01-01

MoSi 2 /SiC–Mo 2 C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo 2 C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi 2 /SiC layer on the upper part of Mo 2 C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500 °C, 1200 °C, 1400 °C and 1600 °C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60 min at 1600 °C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo 2 C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi 2 /SiC composite layer.

Adsorption, hydrogenation and dehydrogenation of C2H on a CoCu bimetallic layer

Science.gov (United States)

Wu, Donghai; Yuan, Jinyun; Yang, Baocheng; Chen, Houyang

2018-05-01

In this paper, adsorption, hydrogenation and dehydrogenation of C2H on a single atomic layer of bimetallic CoCu were investigated using first-principles calculations. The CoCu bimetallic layer is formed by Cu replacement of partial Co atoms on the top layer of a Co(111) surface. Our adsorption and reaction results showed those sites, which have stronger adsorption energy of C2H, possess higher reactivity. The bimetallic layer possesses higher reactivity than either of the pure monometallic layer. A mechanism of higher reactivity of the bimetallic layer is proposed and identified, i.e. in the bimetallic catalyst, the catalytic performance of one component is promoted by the second component, and in our work, the catalytic performance of Co atoms in the bimetallic layer are improved by introducing Cu atoms, lowing the activation barrier of the reaction of C2H. The bimetallic layer could tune adsorption and reaction of C2H by modulating the ratio of Co and Cu. Results of adsorption energies and adsorption configurations reveal that C2H prefers to be adsorbed in parallel on both the pure Co metallic and CoCu bimetallic layers, and Co atoms in subsurface which support the metallic or bimetallic layer have little effect on C2H adsorption. For hydrogenation reactions, the products greatly depend on the concentration and initial positions of hydrogen atoms, and the C2H hydrogenation forming acetylene is more favorable than forming vinylidene in both thermodynamics and kinetics. This study would provide fundamental guidance for hydrocarbon reactions on Co-based and/or Cu-based bimetallic surface chemistry and for development of new bimetallic catalysts.

Synthesis and magnetic properties of layered MnPSxSe3-x (0 < x < 3) and corresponding intercalation compounds of 2,2'-bipyridine

International Nuclear Information System (INIS)

Yan, Xiaobing; Chen, Xingguo; Qin, Jingui

2011-01-01

Graphical abstract: A series of new layered MnPS x Se 3-x (0 x Se 3-x exhibited antiferromagnetism similar to MnPS 3 or MnPSe 3 , but the intercalation of 2,2'-bipyridine can dramatically change the properties of MnPS x Se 3-x slab. Research highlights: → A series of new MnPS x Se 3-x are designed and synthesized for the first time and their layered structure has been determined. → The intercalation chemistry has been initially studied via the intercalation of 2,2'-bipyridine with MnPS x Se 3-x . → The magnetic properties of the series MnPS x Se 3-x and the corresponding intercalation compounds of 2,2'-bipydine have been studied. And the relationship between the structure and the magnetic propertied has been primarily explored. -- Abstract: In this work, we synthesize a series of new MnPS x Se 3-x (0 1-y PS x Se 3-x (bipy) 4y , x = 1.2, 1.8 and 2.4) via the intercalation of 2,2'-bipyridine with MnPS x Se 3-x . XRD results confirm that MnPS x Se 3-x compounds show the layered structure and can be regarded as the solid solution of MnPS 3 and MnPSe 3 . Magnetic measurements indicate that MnPS x Se 3-x compounds exhibit paramagnetism with negative Weiss constant in the paramagnetic temperature region, and an antiferromagnetic phase transition occurs at the Neel temperature. It is found that the magnetic properties of MnPS x Se 3-x slab are dramatically changed after the intercalation of 2,2'-bipyridine, which is close related to the relative ratio of S and Se atom as well as the intralayered Mn 2+ vacancies of MnPS x Se 3-x slab.

Cu2+ in layered compounds: origin of the compressed geometry in the model system K2ZnF4:Cu2+.

Science.gov (United States)

Aramburu, J A; García-Lastra, J M; García-Fernández, P; Barriuso, M T; Moreno, M

2013-06-17

Many relevant properties (including superconductivity and colossal magnetoresistance) of layered materials containing Cu(2+), Ag(2+), or Mn(3+) ions are commonly related to the Jahn-Teller instability. Along this line, the properties of the CuF6(4-) complex in the K2ZnF4 layered perovskite have recently been analyzed using a parametrized Jahn-Teller model with an imposed strain [Reinen, D. Inorg. Chem.2012, 51, 4458]. Here, we present results of ab initio periodic supercell and cluster calculations on K2ZnF4:Cu(2+), showing unequivocally that the actual origin of the unusual compressed geometry of the CuF6(4-) complex along the crystal c axis in that tetragonal lattice is due to the presence of an electric field due to the crystal surrounding the impurity. Our calculations closely reproduce the experimental optical spectrum. The calculated values of the equilibrium equatorial and axial Cu(2+)-F(-) distances are, respectively, R(ax) = 193 pm and R(eq) = 204 pm, and so the calculated distortion R(ax) - R(eq) = 11 pm is three times smaller than the estimated through the parametrized Jahn-Teller model. As a salient feature, we find that if the CuF6(4-) complex would assume a perfect octahedral geometry (R(ax) = R(eq) = 203 pm) the antibonding a(1g)*(∼3z(2) - r(2)) orbital is placed above b(1g)*(∼x(2) - y(2)) with a transition energy E((2)A(1g) → (2)B(1g)) = 0.34 eV. This surprising fact stresses that about half the experimental value E((2)A(1g) → (2)B(1g)) = 0.70 eV is not due to the small shortening of the axial Cu(2+)-F(-) distance, but it comes from the electric field, E(R)(r), created by the rest of the lattice ions on the CuF6(4-) complex. This internal field, displaying tetragonal symmetry, is thus responsible for the compressed geometry in K2ZnF4:Cu(2+) and the lack of symmetry breaking behind the ligand relaxation. Moreover, we show that the electronic energy gain in this process comes from bonding orbitals and not from antibonding ones. The present

Plasma nitriding of CA-6NM steel: effect of H2 + N2 gas mixtures in nitride layer formation for low N2 contents at 500 ºC

Directory of Open Access Journals (Sweden)

Angela Nardelli Allenstein

2010-12-01

Full Text Available This work aims to characterize the phases, thickness, hardness and hardness profiles of the nitride layers formed on the CA-6NM martensitic stainless steel which was plasma nitrided in gas mixtures containing different nitrogen amounts. Nitriding was performed at 500 ºC temperature, and 532 Pa (4 Torr pressure, for gas mixtures of 5% N2 + 95% H2, 10% N2 + 90% H2, and 20% N2 + 80% H2, and 2 hours nitriding time. A 6 hours nitriding time condition for gas mixture of 5% N2 + 95% H2 was also studied. Nitrided samples results were compared with non-nitrided condition. Thickness and microstructure of the nitrided layers were characterized by optical microscopy (OM, using Villela and Nital etchants, and the phases were identified by X-ray diffraction. Hardness profiles and hardness measured on surface steel were determined using Vickers hardness and nanoindentation tester, respectively. It was verified that nitrided layer produced in CA-6NM martensitc stainless steel is constituted of compound layer, being that formation of the diffusion zone was not observed for the studied conditions. The higher the nitrogen amounts in gas mixture the higher is the thickness of the nitrided layer and the probability to form different nitride phases, in the case γ'-Fe4N, ε-Fe2-3N and CrN phases. Intrinsic hardness of the nitrided layers produced in the CA-6NM stainless steel is about 12-14 GPa (~1200-1400 HV.

The synthesis of the 2H, 3H, and 14C-isotopomers of 2'-deoxy-2',2'-difluorocytidine hydrochloride, an anti-tumor compound

International Nuclear Information System (INIS)

Wheeler, W.J.; Mabry, T.E.; Jones, C.D.

1991-01-01

The 2 H, 3 H, and 14 C-isotopomers of 2'-deoxy-2', 2'-difluorocytidine hydrochloride (gemcitabine hydrochloride) have been synthesized in two radiochemical steps from the reaction of bis-trimethylsilylcytosine-[2- 14 C] and 3,5-O-bis-benzoyl-1-O-methanesulfonyl-2-deoxy-2,2-difluororibose. A mixture of anomers of 3',5'-dibenzoyl-2'-deoxy-2',2'-difluorocytidine or its 14 C-isotopomer were obtained which were readily separated by crystallization from ethyl acetate. Deprotection using methanolic ammonia yielded the target compound. The 2 H and 3 H-isotopomers were prepared by deuterium (or tritium) gas hydrogenolysis of 5-iodo-2'-deoxy-2',2'-difluorocytidine. (author)

A Layered Solution Crystal Growth Technique and the Crystal Structure of (C 6H 5C 2H 4NH 3) 2PbCl 4

Science.gov (United States)

Mitzi, D. B.

1999-07-01

Single crystals of the organic-inorganic perovskite (C6H5C2H4NH3)2PbCl4 have been grown at room temperature using a layered solution approach. The bottom solution layer, contained within a long straight tube, consists of PbCl2 dissolved in concentrated aqueous HCl. A less dense layer of methanol is carefully placed on top of the HCl/PbCl2 solution using a syringe. Finally, a stoichiometric quantity of C6H5C2H4NH2 (relative to the PbCl2) is added to the top of the column. As the layers slowly diffuse together, well-formed crystals of (C6H5C2H4NH3)2PbCl4 appear near the interface between the HCl/PbCl2 and C6H5C2H4NH2 solutions. The thick, plate-like crystals are well suited for X-ray crystallography studies. Room temperature intensity data were refined using a triclinic (Poverline1) cell (a=11.1463(3) Å, b=11.2181(3) Å, c=17.6966(5) Å, α= 99.173(1)°, β=104.634(1)°, γ=89.999(1)°, V=2111.8(1) Å3, Z=4, Rf/Rw=0.031/0.044). The organic-inorganic layered perovskite structure features well-ordered sheets of corner-sharing distorted PbCl6 octahedra separated by bilayers of phenethylammonium cations. Tilting and rotation of the PbCl6 octahedra within the perovskite sheets, coupled with organic cation ordering, leads to the unusual in-sheet 2ap×2ap superstructure, where ap is the lattice constant for the ideal cubic perovskite.

Quadruple-layered perovskite (CuCl)Ca2NaNb4O13

International Nuclear Information System (INIS)

Kitada, A.; Tsujimoto, Y.; Yamamoto, T.; Kobayashi, Y.; Narumi, Y.; Kindo, K.; Aczel, A.A.; Luke, G.M.; Uemura, Y.J.; Kiuchi, Y.; Ueda, Y.; Yoshimura, K.; Ajiro, Y.; Kageyama, H.

2012-01-01

We will present the synthesis, structure and magnetic properties of a new quadruple-layered perovskite (CuCl)Ca 2 NaNb 4 O 13 . Through a topotactic ion-exchange reaction with CuCl 2 , the precursor RbCa 2 NaNb 4 O 13 presumably having an incoherent octahederal tliting changes into (CuCl)Ca 2 NaNb 4 O 13 with a 2a p ×2a p ×2c p superstructure (tetragonal; a=7.73232(5) Å, c=39.2156(4) Å). The well-defined superstructure for the ion-exchanged product should be stabilized by the inserted CuCl 4 O 2 octahedral layers that firmly connect with neighboring perovskite layers. Magnetic studies show the absence of long-range magnetic ordering down to 2 K despite strong in-plane interactions. Aleksandrov′s group theory and Rietveld refinement of synchrotron X-ray diffraction data suggest the structure to be of I4/mmm space group with in-phase tilting along the a and b axes, a two-tilt system (++0). - Graphical Abstract: We present a quadruple-layered copper oxyhalide (CuCl)Ca 2 NaNb 4 O 13 synthesized through a topotactic ion-exchange reaction of RbCa 2 NaNb 4 O 13 with CuCl 2 . The compound has a well-defined superstructure. Magnetic studies suggest the absence of magnetic order even at 2 K. Highlights: ► (CuCl)Ca 2 NaNb 4 O 13 was prepared by ion-exchange reaction of RbCa 2 NaNb 4 O 13 with CuCl 2 . ► Compound has a 2a p ×2a p ×2c p superstructure (tetragonal; a=7.73 Å, c=39.21 Å). ► Such a well-defined superstructure was not observed in the precursor compound. ► Aleksandrov′s theory and Rietveld study suggest a (++0) octahedral tilting (I4/mmm). ► Magnetic studies revealed the absence of magnetic order down to 2 K.

Characterization of trace gases measured over Alberta oil sands mining operations: 76 speciated C2-C10 volatile organic compounds (VOCs), CO2, CH4, CO, NO, NO2, NOy, O3 and SO2

Science.gov (United States)

Simpson, I. J.; Blake, N. J.; Barletta, B.; Diskin, G. S.; Fuelberg, H. E.; Gorham, K.; Huey, L. G.; Meinardi, S.; Rowland, F. S.; Vay, S. A.; Weinheimer, A. J.; Yang, M.; Blake, D. R.

2010-12-01

Oil sands comprise 30% of the world's oil reserves and the crude oil reserves in Canada's oil sands deposits are second only to Saudi Arabia. The extraction and processing of oil sands is much more challenging than for light sweet crude oils because of the high viscosity of the bitumen contained within the oil sands and because the bitumen is mixed with sand and contains chemical impurities such as sulphur. Despite these challenges, the importance of oil sands is increasing in the energy market. To our best knowledge this is the first peer-reviewed study to characterize volatile organic compounds (VOCs) emitted from Alberta's oil sands mining sites. We present high-precision gas chromatography measurements of 76 speciated C2-C10 VOCs (alkanes, alkenes, alkynes, cycloalkanes, aromatics, monoterpenes, oxygenated hydrocarbons, halocarbons and sulphur compounds) in 17 boundary layer air samples collected over surface mining operations in northeast Alberta on 10 July 2008, using the NASA DC-8 airborne laboratory as a research platform. In addition to the VOCs, we present simultaneous measurements of CO2, CH4, CO, NO, NO2, NOy, O3 and SO2, which were measured in situ aboard the DC-8. Carbon dioxide, CH4, CO, NO, NO2, NOy, SO2 and 53 VOCs (e.g., non-methane hydrocarbons, halocarbons, sulphur species) showed clear statistical enhancements (1.1-397×) over the oil sands compared to local background values and, with the exception of CO, were greater over the oil sands than at any other time during the flight. Twenty halocarbons (e.g., CFCs, HFCs, halons, brominated species) either were not enhanced or were minimally enhanced (industry fell into two groups: (1) evaporative emissions from the oil sands and its products and/or from the diluent used to lower the viscosity of the extracted bitumen (i.e., C4-C9 alkanes, C5-C6 cycloalkanes, C6-C8 aromatics), together with CO; and (2) emissions associated with the mining effort, such as upgraders (i.e., CO2, CO, CH4, NO, NO2, NOy

CHARGE-TRANSFER BETWEEN LAYERS IN MISFIT LAYER COMPOUNDS

NARCIS (Netherlands)

WIEGERS, GA

1995-01-01

Electron donation from MX double layers to TX(2) sandwiches, the interlayer bonding and the localization of conduction electrons in misfit layer compounds (MX)(p)(TX(2))(n) (M=Sn, Pb, Sb, Bi, rare earth metals; T=Ti, V, Cr, Nb, Ta; X=S, Se; 1.08

2) are discussed.

In-situ fabrication of MoSi{sub 2}/SiC–Mo{sub 2}C gradient anti-oxidation coating on Mo substrate and the crucial effect of Mo{sub 2}C barrier layer at high temperature

Energy Technology Data Exchange (ETDEWEB)

Liu, Jun [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); State Key Laboratory of New Ceramics and Fine Processing, Beijing 100084 (China); Gong, Qianming, E-mail: gongqianming@mail.tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); State Key Laboratory of New Ceramics and Fine Processing, Beijing 100084 (China); Shao, Yang; Zhuang, Daming [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); State Key Laboratory of New Ceramics and Fine Processing, Beijing 100084 (China); Liang, Ji [Key Laboratory for Advanced Materials Processing Technology, Ministry of Education, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

2014-07-01

MoSi{sub 2}/SiC–Mo{sub 2}C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo{sub 2}C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi{sub 2}/SiC layer on the upper part of Mo{sub 2}C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), backscattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500 °C, 1200 °C, 1400 °C and 1600 °C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60 min at 1600 °C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo{sub 2}C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi{sub 2}/SiC composite layer.

Crystal structure, thermochromic and magnetic properties of organic-inorganic hybrid compound: (C7H7N2S)2CuCl4

Science.gov (United States)

Vishwakarma, Ashok K.; Kumari, Reema; Ghalsasi, Prasanna S.; Arulsamy, Navamoney

2017-08-01

The synthesis, thermal analysis, crystal structure and magnetic properties of (2-aminobenzothiazolium)2CuCl4, organic-inorganic hybrid compound, have been described. The compound crystallizes in the monoclinic space group P21/c with two formula units in a unit cell of dimensions a = 6.9522(4) Å, b = 9.6979(4) Å, c = 13.9633(6) Å, β = 97.849(3)° and volume 930.83(8) Å3 at 150(2) K. The structure consists of isolated nearly square planer [CuC14]2- units, with somewhat longer than normal Cusbnd Cl bond lengths [Cusbnd Cl (average) = 2.2711 Å]. The magnetic measurements of (2-aminobenzothiazolium)2CuCl4 using SQUID magnetometer show paramagnetic nature of the compound. Thermal measurements (TG-DTA and DSC) on this compound showed reversible phase transition at 83 °C. This transition is accompanied by the reversible change in colour of the prismatic crystal from green to dark brown, thermochromic behaviour. Temperature dependent EPR measurements on powdered sample ascertain change in coordination sphere around Cu(II) with shift in g|| = 2.150 and g⊥ = 2.071 at room temperature, typical of square planar, to g|| = 2.201 and g⊥ = 2.182 at 170 °C, typical of distorted tetrahedral geometry.

Identification of possible factors impacting dental students' ability to locate MB2 canals in maxillary molars.

Science.gov (United States)

Park, Ellen; Chehroudi, Babak; Coil, Jeffrey M

2014-05-01

This study examined the effect of the access size and straight-line path of access on third-year dental students' ability to locate a second mesiobuccal (MB2) canal in maxillary first and second molars. One hundred and six third-year dental students at one Faculty of Dentistry performed simulated root canal treatment with the aid of 2x magnification loupes on extracted teeth. A postgraduate endodontic student subsequently made a reasonable search for an untreated MB2 canal with the aid of a dental operating microscope. The mesiobuccal roots were then sectioned horizontally for determination of the canal configuration. The dental students were able to treat an MB2 canal in 15.8 percent of the teeth, but this was not associated with satisfactory access criteria. The postgraduate endodontic student identified an MB2 canal in 54.7 percent of the remaining tooth samples excluding those where the MB2 canal was found by the dental students; this represented 94.3 percent of those teeth confirmed by horizontal sectioning of the root to have an MB2 canal. The postgraduate student troughed, on average, 2.6 mm before negotiating the MB2 canal. As satisfactory access criteria and straight-line path of access did not correlate with the dental students' ability to find a second mesiobuccal canal, this result has important implications for educational goals with respect to endodontic treatment of maxillary molar teeth.

ELECTRONIC-STRUCTURE OF THE MISFIT-LAYER COMPOUND (SNS)(1.17)NBS2 DEDUCED FROM BAND-STRUCTURE CALCULATIONS AND PHOTOELECTRON-SPECTRA

NARCIS (Netherlands)

FANG, CM; ETTEMA, ARHF; HAAS, C; WIEGERS, GA; VANLEUKEN, H; DEGROOT, RA

1995-01-01

In order to understand the electronic structure of the misfit-layer compound (SnS)(1.17)NbS2 we carried out an ab initio band-structure calculation of the closely related commensurate compound (SnS)(1.20)NbS2. The band structure is compared with calculations for NbS2 and for hypothetical SnS with

Raman spectroscopy of few-layer graphene prepared by C2–C6 cluster ion implantation

International Nuclear Information System (INIS)

Wang, Z.S.; Zhang, R.; Zhang, Z.D.; Huang, Z.H.; Liu, C.S.; Fu, D.J.; Liu, J.R.

2013-01-01

Few-layer graphene has been prepared on 300 nm-thick Ni films by C 2 –C 6 cluster ion implantation at 20 keV/cluster. Raman spectroscopy reveals significant influence of the number of atoms in the cluster, the implantation dose, and thermal treatment on the structure of the graphene layers. In particular, the graphene samples exhibit a sharp G peak at 1584 cm −1 and 2D peaks at 2711–2717 cm −1 . The I G /I 2D ratios higher than 1.70 and I G /I D ratio as high as 1.95 confirm that graphene sheets with low density of defects have been synthesized with much improved quality by ion implantation with larger clusters of C 4 –C 6

The electronic structure of the metastable layer compound 1T-CrSe2

NARCIS (Netherlands)

Fang, C.M.; Groot, R.A. de; Wiegers, G.A.; Haas, C.; vanBruggen, C.F.; deGroot, R.A.

1997-01-01

The electronic structure of the metastable compound 1T-CrSe2 (a = 3.399 Å, c = 5.911 Å, space group P_3m1) was calculated with and without spin polarization using the LSW method. The energy is 0.29 eV/mol CrSe2 lower for the spin-polarized calculation. The total magnetic moment of +2.44 μB on Cr

PEALD grown high-k ZrO{sub 2} thin films on SiC group IV compound semiconductor

Energy Technology Data Exchange (ETDEWEB)

Khairnar, A. G., E-mail: agkhairnar@gmail.com; Patil, V. S.; Agrawal, K. S.; Salunke, R. S.; Mahajan, A. M., E-mail: ammahajan@nmu.ac.in [North Maharashtra University, Department of Electronics, School of Physical Sciences (India)

2017-01-15

The study of ZrO{sub 2} thin films on SiC group IV compound semiconductor has been studied as a high mobility substrates. The ZrO{sub 2} thin films were deposited using the Plasma Enhanced Atomic Layer Deposition System. The thickness of the thin films were measured using ellipsometer and found to be 5.47 nm. The deposited ZrO{sub 2} thin films were post deposition annealed in rapid thermal annealing chamber at temperature of 400°Ð¡. The atomic force microscopy and X-гау photoelectron spectroscopy has been carried out to study the surface topography, roughness and chemical composition of thin film, respectively.

Direct electrochemistry of myoglobin in a layer-by-layer film on an ionic liquid modified electrode containing CeO2 nanoparticles and hyaluronic acid

International Nuclear Information System (INIS)

Gao, R.; Zheng, J.; Zheng, X.

2011-01-01

We describe an ionic liquid modified electrode (CPE-IL) for sensing hydrogen peroxide (HP) that was modified by the layer-by-layer technique with myoglobin (Mb). In addition, the surface of the electrode was modified with CeO 2 nanoparticles (nano-CeO 2 ) and hyaluronic acid. UV-vis and FTIR spectroscopy confirmed that Mb retains its native structure in the composite film. Scanning electron microscopy showed that the nano-CeO 2 closely interact with Mb to form an inhomogeneously distributed film. Cyclic voltammetry reveals a pair of quasi-reversible redox peaks of Mb, with the cathodic peak at -0. 357 V and the anodic peak at -0. 269 V. The peak separation (ΔE p ) and the formal potential (E σ ) are 88 mV and -0. 313 V (vs. Ag/AgCl), respectively. The Mb immobilized in the modified electrode displays an excellent electrocatalytic activity towards HP in the 0. 6 to 78. 0 μM concentration range. The limit of detection is 50 nM (S/N = 3), and then the Michaelis-Menten constant is 71. 8 μM. We believe that such a composite film has potential to further investigate other redox proteins and in the fabrication of third-generation biosensors. (author)

Synthesis of Pt@TiO2@CNTs Hierarchical Structure Catalyst by Atomic Layer Deposition and Their Photocatalytic and Photoelectrochemical Activity.

Science.gov (United States)

Liao, Shih-Yun; Yang, Ya-Chu; Huang, Sheng-Hsin; Gan, Jon-Yiew

2017-04-29

Pt@TiO2@CNTs hierarchical structures were prepared by first functionalizing carbon nanotubes (CNTs) with nitric acid at 140 °C. Coating of TiO2 particles on the CNTs at 300 °C was then conducted by atomic layer deposition (ALD). After the TiO2@CNTs structure was fabricated, Pt particles were deposited on the TiO2 surface as co-catalyst by plasma-enhanced ALD. The saturated deposition rates of TiO2 on a-CNTs were 1.5 Å/cycle and 0.4 Å/cycle for substrate-enhanced process and linear process, respectively. The saturated deposition rate of Pt on TiO2 was 0.39 Å/cycle. The photocatalytic activities of Pt@TiO2@CNTs hierarchical structures were higher than those without Pt co-catalyst. The particle size of Pt on TiO2@CNTs was a key factor to determine the efficiency of methylene blue (MB) degradation. The Pt@TiO2@CNTs of 2.41 ± 0.27 nm exhibited the best efficiency of MB degradation.

Synthesis, structure and properties of layered iron-oxychalcogenides Nd2Fe2Se2−xSxO3

International Nuclear Information System (INIS)

Liu, Y.; Zhang, S.B.; Tan, S.G.; Yuan, B.; Kan, X.C.; Zu, L.; Sun, Y.P.

2015-01-01

A new series of sulfur-substituted iron-oxychalcogenides Nd 2 Fe 2 Se 2−x S x O 3 (0≤x≤0.4) was synthesized by solid state reaction method, and investigated by structure, transport, magnetic and specific heat measurements. The compounds crystallize in the layered tetragonal structure with I4/mmm space group, and show semiconducting behavior. The large discrepancy between the activation energies for conductivity, E ρ (152–202 meV), and thermopower, E S (15.6–39.8 meV), indicates the polaronic transport mechanism of the carrier. The parent compound Nd 2 Fe 2 Se 2 O 3 exhibits a frustrated antiferromagnetic (AFM) ground state, and the S-substitution induces an enhanced ferromagnetic (FM) component and possible increased degree of frustration. - Graphical abstract: The crystal structure of Nd 2 Nd 2 Fe 2 Se 2−x S x O 3 is built up by stacking fluorite-like Nd 2 O 2 layers and anti-CuO 2 -type Fe 2 O(Se/S) 2 layers with Fe 2+ cations coordinated by two in-plane O 2- and four Se 2- above and below the square Fe 2 O plane. - Highlights: • We have synthesized a new series of layered iron-oxychalcogenides Nd 2 Fe 2 Se 2−x S x O 3 . • They crystallize in layered tetragonal structure and show semiconducting behavior. • The transport analysis indicates the polaronic transport mechanism of the carrier. • The parent compound shows a frustrated antiferromagnetic (AFM) ground state. • The S-substitution induces an enhanced ferromagnetic (FM) component

The new carbodiimide Li_2Gd_2Sr(CN_2)_5 having a crystal structure related to that of Gd_2(CN_2)_3

International Nuclear Information System (INIS)

Unverfehrt, Leonid; Stroebele, Markus; Meyer, H. Juergen

2013-01-01

The new carbodiimide compounds Li_2RE_2Sr(CN_2)_5 (RE = Sm, Gd, Eu, Tb) were prepared by a straight forward solid state metathesis reaction of REF_3, SrF_2, and Li_2(CN_2) at around 600 C. The crystal structure of Li_2Gd_2Sr(CN_2)_5 was solved based on X-ray single-crystal diffraction data. Corresponding Li_2RE_2Sr(CN_2)_5 compounds were analyzed by isotypic indexing of their powder patterns. The crystal structure of Li_2Gd_2Sr(CN_2)_5 can be well related to that of Gd_2(CN_2)_3, because both structures are based on layered structures composed of close packed layers of [N=C=N]"2"- sticks, alternating with layers of metal ions. The crystal structure of Li_2Gd_2Sr(CN_2)_5 can be considered to contain an ABC layer sequence of [N = C=N]"2"- layers with the interlayer voids being occupied by (three) distinct types of cations. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

IN SITU MEASUREMENTS OF C2-C10 VOLATILE ORGANIC COMPOUNDS ABOVE A SIERRA NEVADA PONDEROSA PINE PLANTATION

Science.gov (United States)

A fully automated GC-FID system was designed and built to measure ambient concentrations of C2-C10 volatile organic compounds, including many oxygenated compounds, without using liquid cryogen. It was deployed at Blodgett Forest Research Station in Georgetown, CA USA, 38 deg 53' ...

Raman evidence of the formation of LT-LiCoO 2 thin layers on NiO in molten carbonate at 650°C

Science.gov (United States)

Mendoza, L.; Baddour-Hadjean, R.; Cassir, M.; Pereira-Ramos, J. P.

2004-03-01

The structural evolution of thin layers of Co 3O 4 elaborated on nickel-based substrates in the Li 2CO 3-Na 2CO 3 carbonate eutectic at 650 °C as a function of time immersion is reported. Raman microspectrometry has been applied in order to provide more information on the nature of the protective cobalt oxide layers. The typical Raman fingerprint of the LT-LiCoO 2 compound has been obtained, with four well defined bands at 449, 484, 590 and 605 cm -1, while XRD data are unable to distinguish the layered phase (HT) from the spinel one (LT). The mechanical stability of such films does not exceed 10 h in direct contact with the molten carbonate bulk at 650 °C; nevertheless, these conditions are much more corrosive than in a molten carbonate fuel cell (MCFC).

Sterically crowded monomeric neutral bis(benzamidinato) compounds of aluminium, [PhC(NSiMe(3))(2)](2)AlX (X=Cl, H); X-ray crystal structure of [PhC(NSiMe(3))(2)]2AlH

NARCIS (Netherlands)

Duchateau, R; Meetsma, A; Teuben, JH

1996-01-01

AlCl3 reacts with [PhC(NSiMe(3))(2)]Li(OEt(2)) to afford the bis(N,N'-bis(trimethylsilyl)benzamidinato)aluminium chloro compound which, on treatment with KBEt(3)H, yields the structurally characterized monomeric hydride derivative, [PhC(NSiMe(3))(2)]2AlH, whose reactivity towards unsaturated

2. Intermetallic compounds with lanthanides

International Nuclear Information System (INIS)

Elemans, J.B.A.A.

1975-01-01

Theoretical considerations are given concerning the structures of intermetallic compounds of the lanthanides and thorium (R) on the one hand, and with Fe, Co or Ni (M) on the other. They all derive from the parent composition RM 5 with the CaCu 5 hexagonal structure. This consists of alternate layers in which the M atoms are distinguished as M 1 and M 2 . The other compounds whose structures are studied are obtained by systematic replacement of R by M, or vice versa. In the first type, every third R is replaced by two M's yielding R 2 M 17 compounds. The substitution may be truly random or structured in two ways: so that either the hexagonal structure is maintained or that it is converted into a rhombihedral one. In the second type, one M (in a M 1 position) out of every five is replaced by one R, giving rise to RM 2 compounds which form Laves phases. In the third type, the M 1 's are replaced by R's, resulting in compounds RM 3 . In the fourth type, every third M is replaced by R, yielding R 2 M 7 compounds. With M = Co and R a light lanthanide, the compounds are ferromagnets; with R yttrium, thorium, or a heavy lanthanide, they are ferrimagnets. The preparation of the compounds in an arc-melting apparatus under an Ar-atmosphere followed by annealing is described

Improved tribological properties of TiC with porous nanostructured TiO2 intermediate layer

International Nuclear Information System (INIS)

Shanaghi, Ali; Ahangarani, Shahrokh; Sabour Rouhaghdam, Ali Reza; Chu, Paul K.

2011-01-01

Highlights: ► The porous TiO 2 nanoparticle coating is deposited as an intermediate layer on steel. ► A homogenous and low friction TiC nanostructure coating is deposited by plasma CVD. ► Intermediate layer can be determined the nucleation and growth of the TiC coating. ► The porous interlayer improves the friction and wear of the TiC nanostructure coating. - Abstract: The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO 2 coating is deposited as an intermediate layer on hot-work steel (H 11 ) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO 2 interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Curcumin induces down-regulation of EZH2 expression through the MAPK pathway in MDA-MB-435 human breast cancer cells.

Science.gov (United States)

Hua, Wen-Feng; Fu, Yong-Shui; Liao, Yi-Ji; Xia, Wen-Jie; Chen, Yang-Chao; Zeng, Yi-Xin; Kung, Hsiang-Fu; Xie, Dan

2010-07-10

Curcumin, a natural compound isolated from turmeric, may inhibit cell proliferation in various tumor cells through a mechanism that is not fully understood. The enhancer of zeste homolog 2 (EZH2) gene is overexpressed in human breast cancers with poor prognosis. In this study, we observed a dose- and time-dependent down-regulation of expression of EZH2 by curcumin that correlates with decreased proliferation in the MDA-MB-435 breast cancer cell line. The curcumin treatment resulted in an accumulation of cells in the G(1) phase of the cell cycle. Further investigation revealed that curcumin-induced down-regulation of EZH2 through stimulation of three major members of the mitogen-activated protein kinase (MAPK) pathway: c-Jun NH2-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 kinase. These data suggest that an underlying mechanism of the MAPK pathway mediates the down-regulation of EZH2, thus contributing to the anti-proliferative effects of curcumin against breast cancer. Copyright 2010 Elsevier B.V. All rights reserved.

Partial exchange of the Li+, Na+ and K+ alkaline cations in the HNi(PO4).H2O layered compound

International Nuclear Information System (INIS)

Escobal, Jaione; Mesa, Jose; Pizarro, Jose; Bazan, Begona; Arriortua, Maria; Rojo, Teofilo

2006-01-01

The exchange of the Li + (1), Na + (2) and K + (3) alkaline cations in the layered HNi(PO 4 ).H 2 O was carried out starting from a methanolic solution containing the Li(OH).H 2 O hydroxide for (1) and the M(OH) (M=Na and K) hydroxides together with the (C 6 H 13 NH 2 ) 0.75 HNiPO 4 .H 2 O phases for (2) and (3). The compounds are stable until, approximately, 280 o C for (1) and 400 deg. C for phases (2) and (3), respectively. The IR spectra show the bands belonging to the water molecule and the (PO 4 ) 3- oxoanion. The diffuse reflectance spectra indicate the existence of Ni(II), d 8 , cations in slightly distorted octahedral geometry. The calculated Dq and Racah (B and C) parameters have a mean value of Dq=765, B=905 and C=3895cm -1 , respectively, in accordance with the values obtained habitually for this octahedral Ni(II) cation. The study of the exchange process performed by X-ray powder diffraction indicates that the exchange of the Li + cation in the lamellar HNi(PO 4 ).H 2 O phase is the minor rapid reaction, whereas the exchange of the Na + and K + cations needs the presence of the intermediate (C 6 H 13 NH 2 ) 0.75 HNiPO 4 .H 2 O intercalate in order to obtain the required product with the sodium and potassium ions. The Scanning electronic microscopy (SEM) images show a mean size of particle of 5μm. The Li + exchanged compound exhibits small ionic conductivity (Ωcm -1 is in the 10 -8 -10 -9 range) probably restrained by the methanol solvent. Magnetic measurements carried out from 5K to room temperature indicate antiferromagnetic coupling as the major interaction in the three phases. Notwithstanding the Li and K phases show a weak ferromagnetism at low temperatures

Electrocatalytic Production of C3-C4 Compounds by Conversion of CO2 on a Chloride-Induced Bi-Phasic Cu2O-Cu Catalyst.

Science.gov (United States)

Lee, Seunghwa; Kim, Dahee; Lee, Jaeyoung

2015-12-01

Electrocatalytic conversion of carbon dioxide (CO2) has recently received considerable attention as one of the most feasible CO2 utilization techniques. In particular, copper and copper-derived catalysts have exhibited the ability to produce a number of organic molecules from CO2. Herein, we report a chloride (Cl)-induced bi-phasic cuprous oxide (Cu2O) and metallic copper (Cu) electrode (Cu2OCl) as an efficient catalyst for the formation of high-carbon organic molecules by CO2 conversion, and identify the origin of electroselectivity toward the formation of high-carbon organic compounds. The Cu2OCl electrocatalyst results in the preferential formation of multi-carbon fuels, including n-propanol and n-butane C3-C4 compounds. We propose that the remarkable electrocatalytic conversion behavior is due to the favorable affinity between the reaction intermediates and the catalytic surface. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual-Layer Oxidation-Protective Plasma-Sprayed SiC-ZrB2/Al2O3-Carbon Nanotube Coating on Graphite

Science.gov (United States)

Ariharan, S.; Sengupta, Pradyut; Nisar, Ambreen; Agnihotri, Ankur; Balaji, N.; Aruna, S. T.; Balani, Kantesh

2017-02-01

Graphite is used in high-temperature gas-cooled reactors because of its outstanding irradiation performance and corrosion resistance. To restrict its high-temperature (>873 K) oxidation, atmospheric-plasma-sprayed SiC-ZrB2-Al2O3-carbon nanotube (CNT) dual-layer coating was deposited on graphite substrate in this work. The effect of each layer was isolated by processing each component of the coating via spark plasma sintering followed by isothermal kinetic studies. Based on isothermal analysis and the presence of high residual thermal stress in the oxide scale, degradation appeared to be more severe in composites reinforced with CNTs. To avoid the complexity of analysis of composites, the high-temperature activation energy for oxidation was calculated for the single-phase materials only, yielding values of 11.8, 20.5, 43.5, and 4.5 kJ/mol for graphite, SiC, ZrB2, and CNT, respectively, with increased thermal stability for ZrB2 and SiC. These results were then used to evaluate the oxidation rate for the composites analytically. This study has broad implications for wider use of dual-layer (SiC-ZrB2/Al2O3) coatings for protecting graphite crucibles even at temperatures above 1073 K.

Inherent Electrochemistry and Charge Transfer Properties of Few-Layer Two Dimensional Ti3C2Tx MXene

KAUST Repository

Nayak, Pranati

2018-05-25

We report the effect of Ti3C2Tx MXene flake thickness on its inherent electrochemistry and heterogeneous charge transfer characteristics. It is shown that the Ti3C2Tx undergoes irreversible oxidation in the positive potential window, which strongly depends on the flake thickness and pH of the electrolyte. Few-layer Ti3C2Tx exhibits faster electron transfer kinetics (k0=0.09533 cm/s) with Fe(CN)64−/3− redox mediator compared to multi-layer Ti3C2Tx (k0= 0.00503 cm/s). In addition, few-layer free standing Ti3C2Tx film electrode remains intact after enduring irreversible oxidation.

Inherent Electrochemistry and Charge Transfer Properties of Few-Layer Two Dimensional Ti3C2Tx MXene

KAUST Repository

Nayak, Pranati; Jiang, Qiu; Mohanraman, Rajeshkumar; Anjum, Dalaver H.; Hedhili, Mohamed N.; Alshareef, Husam N.

2018-01-01

We report the effect of Ti3C2Tx MXene flake thickness on its inherent electrochemistry and heterogeneous charge transfer characteristics. It is shown that the Ti3C2Tx undergoes irreversible oxidation in the positive potential window, which strongly depends on the flake thickness and pH of the electrolyte. Few-layer Ti3C2Tx exhibits faster electron transfer kinetics (k0=0.09533 cm/s) with Fe(CN)64−/3− redox mediator compared to multi-layer Ti3C2Tx (k0= 0.00503 cm/s). In addition, few-layer free standing Ti3C2Tx film electrode remains intact after enduring irreversible oxidation.

Design and syntheses of hybrid metal-organic materials based on K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] metallotectons

Science.gov (United States)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao; Wang, Wenqiang; Wang, Lei

2016-05-01

By using K3[M(C2O4)3]·3H2O [M(III)=Fe, Al, Cr] (C2O42-=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C2O4)2(H2O)2}2]·(H-L1)2·H2O 1, [Fe(C2O4)Cl2]·(H2-L2)0.5·(L2)0.5·H2O 2, [{Fe(C2O4)1.5Cl2}2]·(H-L3)43, [Fe2(C2O4)Cl8]·(H2-L4)2·2H2O 4, K[Al(C2O4)3]·(H2-L5)·2H2O 5, K[Al(C2O4)3]·(H-L6)2·2H2O 6, K[Cr(C2O4)3]·2H2O 7, Na[Fe(C2O4)3]·(H-L6)2·2H2O 8 (with L1=4-dimethylaminopyridine, L2=2,3,5,6-tetramethylpyrazine, L3=2-aminobenzimidazole, L4=1,4-bis-(1H-imidazol-1-yl)benzene, L5=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L6=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C2O4)2(H2O)2]- unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C2O4)Cl2]- anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe2(C2O4)3Cl4]4- unit. Compound 4 features distinct [Fe2(C2O4)Cl8]4- units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C2O4)3]3- units and K+ cations. The 1D chains are further extended into 3D antionic H-bonded framework through O-H···O H-bonds. Compounds 6-8 show 2D [KAl(C2O4)3]2- layer, [KCr(C2O4)3]2- layer and [NaFe(C2O4)3]2- layer, respectively.

A study on heterogeneous photocatalytic degradation of various organic compounds using N-Tio2 under Uv-light irradiation

Science.gov (United States)

Srujana, Dhegam; Sailu, Chinta

2018-04-01

The aim of this work is to determine the photocatalytic degradation of mixture of four selected organic compounds are Congo Red (CR), Methylene Blue (MB), Diclofenaec (DC), 4-Chlorophenol (4-CP) have been subjected to Photo catalytic degradation by Ultraviolet (λ=254nm) radiation in presence of Nitrogen-doped Titanium dioxide (N-TiO2) catalyst. This paper focused on the enhancement of photo catalysis by modification of TiO2 employing non-metal ion (Nitrogen) doping. Experiments are conducted with a mixture of equal proportions of organic compounds (CR, MB, DC, and 4-CP) with combined concentrations of 10, 20, 30, 40 and 50 mg/l in water in a batch reactor in presence of N-TiO2catalyst with UV light (λ=254nm). The rate of degradation of each compound is determined by using spectrophotometer. The kinetics of degradation of the selected organic compounds is followed first order rate.

Structural studies of five layer Aurivillius oxides: A2Bi4Ti5O18 (A=Ca, Sr, Ba and Pb)

International Nuclear Information System (INIS)

Ismunandar; Kamiyama, T.; Hoshikawa, A.; Zhou, Q.; Kennedy, B.J.; Kubota, Y.; Kato, K.

2004-01-01

The room temperature structures of the five layer Aurivillius phases A 2 Bi 4 Ti 5 O 18 , (A=Ca, Sr, Ba and Pb) have been refined from powder neutron diffraction data using the Rietveld method. The structures consist of [Bi 2 O 2 ] 2+ layers interleaved with perovskite-like [A 2 Bi 2 Ti 5 O 16 ] 2- blocks. The structures were refined in the orthorhombic space group B2eb (SG. No. 41), Z=4, and the unit cell parameters of the oxides are a=5.4251(2), b=5.4034(1), c=48.486(1); a=5.4650(2), b=5.4625(3), c=48.852(1); a=5.4988(3), b=5.4980(4), c=50.352(1); a=5.4701(2), b=5.4577(2), c=49.643(1) for A=Ca, Sr, Ba and Pb, respectively. The structural features of the compounds were found similar to n=2-4 layers bismuth oxides. The strain caused by mismatch of cell parameter requirements for the [Bi 2 O 2 ] 2+ layers and perovskite-like [A 2 Bi 2 Ti 5 O 16 ] 2- blocks were relieved by tilting of the TiO 6 octahedra. Variable temperature synchrotron X-ray studies for Ca and Pb compounds showed that the orthorhombic structure persisted up to 675 and 475K, respectively. Raman spectra of the compounds are also presented

Electronic structure of the misfit-layer compound (SnS)1.17NbS2 deduced from band-structure calculations and photoelectron spectra

NARCIS (Netherlands)

Fang, C.M.; Ettema, A.R.H.F.; Haas, C.; Wiegers, G.A.; Leuken, H. van; Groot, R.A. de

1995-01-01

In order to understand the electronic structure of the misfit-layer compound (SnS)1.17NbS2 we carried out an ab initio band-structure calculation of the closely related commensurate compound (SnS)1.20NbS2. The band structure is compared with calculations for NbS2 and for hypothetical SnS with

Low-temperature structural transition in the quasi-one-dimensional spin-1/2 compound L i2C u2O (SO4) 2

Science.gov (United States)

Rousse, G.; Rodríguez-Carvajal, J.; Giacobbe, C.; Sun, M.; Vaccarelli, O.; Radtke, G.

2017-04-01

A thorough structural exploration has been made on the quasi-one-dimensional S =1 /2 compound L i2C u2O (SO4) 2 by neutron and synchrotron x-ray diffraction. It reveals the occurrence of a structural transition at 125 K, characterized by a lowering of symmetry from P 42/m to P 1 ¯ , which is possibly driven by an exchange striction mechanism. This transition involves a dimerization of some Cu in the edge-sharing tetrahedral Cu chains. A symmetry mode analysis indicates that one representation, Γ3+Γ4+ , dominates the structural transition. Interestingly, no intermediate structure with P 112 /m symmetry is observed experimentally. Lastly, temperature dependent magnetic susceptibility measurements and neutron diffraction reveal that the magnetic ground state of this compound is a spin-singlet with a spin gap, characterized by the absence of long-range magnetic order down to 1.7 K.

A Double Layer Sensing Electrode “BaTi(1-XRhxO3/Al-Doped TiO2” for NO2 Detection above 600 °C

Directory of Open Access Journals (Sweden)

Bilge Saruhan

2016-04-01

Full Text Available NO2 emission is mostly related to combustion processes, where gas temperatures exceed far beyond 500 °C. The detection of NO2 in combustion and exhaust gases at elevated temperatures requires sensors with high NO2 selectivity. The thermodynamic equilibrium for NO2/NO ≥ 500 °C lies on the NO side. High temperature stability of TiO2 makes it a promising material for elevated temperature towards CO, H2, and NO2. The doping of TiO2 with Al3+ (Al:TiO2 increases the sensitivity and selectivity of sensors to NO2 and results in a relatively low cross-sensitivity towards CO. The results indicate that NO2 exposure results in a resistance decrease of the sensors with the single Al:TiO2 layers at 600 °C, with a resistance increase at 800 °C. This alteration in the sensor response in the temperature range of 600 °C and 800 °C may be due to the mentioned thermodynamic equilibrium changes between NO and NO2. This work investigates the NO2-sensing behavior of duplex layers consisting of Al:TiO2 and BaTi(1-xRhxO3 catalysts in the temperature range of 600 °C and 900 °C. Al:TiO2 layers were deposited by reactive magnetron sputtering on interdigitated sensor platforms, while a catalytic layer, which was synthesized by wet chemistry in the form of BaTi(1-xRhxO3 powders, were screen-printed as thick layers on the Al:TiO2-layers. The use of Rh-incorporated BaTiO3 perovskite (BaTi(1-xRhxO3 as a catalytic filter stabilizes the sensor response of Al-doped TiO2 layers yielding more reliable sensor signal throughout the temperature range.

A thin layer fiber-coupled luminescence dosimeter based on Al2O3:C

DEFF Research Database (Denmark)

Klein, F.A.; Greilich, Steffen; Andersen, Claus Erik

2011-01-01

In this paper we present a fiber-coupled luminescent Al2O3:C dosimeter probe with high spatial resolution (0.1 mm). It is based on thin layers of Al2O3:C crystal powder and a UV-cured acrylate monomer composition. The fabrication of the thin layers is described in detail. No influence of the intr......In this paper we present a fiber-coupled luminescent Al2O3:C dosimeter probe with high spatial resolution (0.1 mm). It is based on thin layers of Al2O3:C crystal powder and a UV-cured acrylate monomer composition. The fabrication of the thin layers is described in detail. No influence...... of the introduced polymer host matrix on the dosimetric properties was observed. Depth-dose measurements with the new detectors in a 142.66 MeV proton and 270.55 MeV/u carbon ion beam are presented as example applications. We used an RL protocol with saturated crystals allowing for time-effective measurements...... without sensitivity corrections. For protons, a relative luminescence efficiency hHCP of 0.715 0.014 was found in the Bragg peak. For carbon ions, a value of 0.498 0.001 was found in the entrance channel, 0.205 0.015 in the Bragg peak, and a mean of 0.413 0.050 in the tail region. The mean range...

Structural variability in neptunium(V) oxalate compounds: synthesis and structural characterization of Na2NpO2(C2O4)OH.H2O.

Science.gov (United States)

Bean, Amanda C; Garcia, Eduardo; Scott, Brian L; Runde, Wolfgang

2004-10-04

Reaction of a (237)Np(V) stock solution in the presence of oxalic acid, calcium chloride, and sodium hydroxide under hydrothermal conditions produces single crystals of a neptunium(V) oxalate, Na(2)NpO(2)(C(2)O(4))OH.H(2)O. The structure consists of one-dimensional chains running down the a axis and is the first example of a neptunium(V) oxalate compound containing hydroxide anions.

High-pressure polymorphism of As2S3 and new AsS2 modification with layered structure

Science.gov (United States)

Bolotina, N. B.; Brazhkin, V. V.; Dyuzheva, T. I.; Katayama, Y.; Kulikova, L. F.; Lityagina, L. V.; Nikolaev, N. A.

2014-01-01

At normal pressure, the As2S3 compound is the most stable equilibrium modification with unique layered structure. The possibility of high-pressure polymorphism of this substance remains questionable. Our research showed that the As2S3 substance was metastable under pressures P > 6 GPa decomposing into two high-pressure phases: As2S3 → AsS2 + AsS. New AsS2 phase can be conserved in the single crystalline form in metastable state at room pressure up to its melting temperature (470 K). This modification has the layered structure with P1211 monoclinic symmetry group; the unit-cell values are a = 7.916(2) Å, b = 9.937(2) Å, c = 7.118(1) Å, β = 106.41° ( Z = 8, density 3.44 g/cm3). Along with the recently studied AsS high-pressure modification, the new AsS2 phase suggests that high pressure polymorphism is a very powerful tool to create new layered-structure phases with "wrong" stoichiometry.

Electrical properties and conduction mechanism of [C2H5NH3]2CuCl4 compound

Science.gov (United States)

Mohamed, C. Ben; Karoui, K.; Jomni, F.; Guidara, K.; Rhaiem, A. Ben

2015-02-01

The [(C2H5)NH3]2CuCl4 compound was prepared and characterized by several technique: the X-ray powder diffraction confirms the purity of the synthetized compound, the differential scanning calorimetric show several phase transitions at 236 K, 330 K, 357 K and 371 K, the dialectical properties confirms the ferroelectric-paraelectric phase transition at 238 K, which is reported by V. Kapustianyk et al. (2007) [1]. The two semi-circles observed in the complex impedance identify the presence of the grain interior and grain boundary contributions to the electrical response in this material. The equivalent circuit is modeled by a combination series of two parallel RP-CPE circuits. The temperature dependence of the alternative current conductivity (σg) and direct current conductivity (σdc) confirm the observed transitions in the calorimetric study. The (AC) electrical conduction in [(C2H5)NH3]2CuCl4 was studied by two processes that can be attributed to a hopping transport mechanism: the non-overlapping small polaron tunneling (NSPT) model in phase III and the correlated barrier hopping (CBH) model in phases I, II, IV, V and VI.

Local structure and defect chemistry of [(SnSe)1.15]m(TaSe2) ferecrystals – A new type of layered intergrowth compound

International Nuclear Information System (INIS)

Grosse, Corinna; Atkins, Ryan; Kirmse, Holm; Mogilatenko, Anna; Neumann, Wolfgang; Johnson, David C.

2013-01-01

Highlights: •The crystal structure of [(SnSe) 1.15 ] m (TaSe 2 ) ferecrystals was analyzed by TEM. •The layers exhibit turbostratic disorder, but we also observed a local ordering. •The structures of the SnSe and TaSe 2 layers are similar to binary SnSe and 2H-TaSe 2 . •An increasing in-plane SnSe grain size with increasing m was observed. •Defect areas with missing, substituted or additional layers were found. -- Abstract: The atomic structure of the family of ferecrystals [(SnSe) 1.15 ] m (TaSe 2 ) (m = 1, 3, and 6) was investigated by means of transmission electron microscopy. The tantalum in the TaSe 2 layers was observed to have trigonal prismatic coordination similar to that found in the 2H polytype of bulk TaSe 2 . The structure of the SnSe constituent was found to be similar to that of orthorhombic α-SnSe. In the compounds with m = 1 and m = 3, regions with a local ordering of the layers along a commensurate axis, similar to the ordering in conventional misfit layer compounds, were observed. However, on a longer range the ferecrystals were found to exhibit a turbostratically disordered structure. Stacking defects were occasionally found in the samples in which a layer is interrupted and the surrounding layers are bent around these defects, while maintaining abrupt interfaces instead of interdiffusing. Volume defects were found in one sample of [(SnSe) 1.15 ] 1 (TaSe 2 ) 1 in which a SnSe layer locally substitutes a part of a TaSe 2 layer without interrupting the surrounding layers

Colossal magnetoresistance in layered manganite Nd2−2xSr1+ ...

Indian Academy of Sciences (India)

starting compounds, have been obtained. Except for x=0.4, which is found to be an antiferromagnetic insulator, all other x values yielded metal–insulator transition and ferromagnetic ordering. Keywords. Colossal magnetoresistance; layered manganites; Nd2−2x Sr1+2x Mn2O7. PACS Nos 75.30.Vn; 71.30.+h. 1. Introduction.

Semiconducting perovskites (2-XC6H4C2H4NH3)2SnI4 (X = F, Cl, Br): steric interaction between the organic and inorganic layers.

Science.gov (United States)

Xu, Zhengtao; Mitzi, David B; Dimitrakopoulos, Christos D; Maxcy, Karen R

2003-03-24

Two new semiconducting hybrid perovskites based on 2-substituted phenethylammonium cations, (2-XC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) (X = Br, Cl), are characterized and compared with the previously reported X = F compound, with a focus on the steric interaction between the organic and inorganic components. The crystal structure of (2-ClC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) is solved in a disordered subcell [C2/m, a = 33.781(7) A, b = 6.178(1) A, c = 6.190(1) A, beta = 90.42(3)(o), and Z = 2]. The structure is similar to the known (2-FC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) structure with regard to both the conformation of the organic cations and the bonding features of the inorganic sheet. The (2-BrC(6)H(4)C(2)H(4)NH(3))(2)SnI(4) system adopts a fully ordered monoclinic cell [P2(1)/c, a = 18.540(2) A, b = 8.3443(7) A, c = 8.7795(7) A, beta = 93.039(1)(o), and Z = 2]. The organic cation adopts the anti conformation, instead of the gauche conformation observed in the X = F and Cl compounds, apparently because of the need to accommodate the additional volume of the bromo group. The steric effect of the bromo group also impacts the perovskite sheet, causing notable distortions, such as a compressed Sn-I-Sn bond angle (148.7(o), as compared with the average values of 153.3 and 154.8(o) for the fluoro and chloro compounds, respectively). The optical absorption features a substantial blue shift (lowest exciton peak: 557 nm, 2.23 eV) relative to the spectra of the fluoro and chloro compounds (588 and 586 nm, respectively). Also presented are transport properties for thin-film field-effect transistors (TFTs) based on spin-coated films of the two hybrid semiconductors.

Optical spectroscopy of two-dimensional layered (C(6)H(5)C(2)H(4)-NH(3))(2)-PbI(4) perovskite.

Science.gov (United States)

Gauthron, K; Lauret, J-S; Doyennette, L; Lanty, G; Al Choueiry, A; Zhang, S J; Brehier, A; Largeau, L; Mauguin, O; Bloch, J; Deleporte, E

2010-03-15

We report on optical spectroscopy (photoluminescence and photoluminescence excitation) on two-dimensional self-organized layers of (C(6)H(5)C(2)H(4)-NH(3))(2)-PbI(4) perovskite. Temperature and excitation power dependance of the optical spectra gives a new insight into the excitonic and the phononic properties of this hybrid organic/inorganic semiconductor. In particular, exciton-phonon interaction is found to be more than one order of magnitude higher than in GaAs QWs. As a result, photoluminescence emission lines have to be interpreted in the framework of a polaron model.

Surfactant-induced layered growth in homoepitaxy of Fe on Fe(100)-c(2 x 2)O reconstruction surface

International Nuclear Information System (INIS)

Kamiko, Masao; Mizuno, Hiroyuki; Chihaya, Hiroaki; Xu, Junhua; Kojima, Isao; Yamamoto, Ryoichi

2007-01-01

In this study, the effects of several surfactants (Pb, Bi, and Ag) on the homoepitaxial growth of Fe(100) were studied and compared. The reflection high-energy electron diffraction measurements clearly reveal that these surfactants enhance the layer-by-layer growth of Fe on an Fe(100)-c(2 x 2)O reconstruction surface. The dependence of growth on the surfactant layer thickness suggests that there exists a suitable amount of surfactant layer that induces a smoother layer-by-layer growth. Comparisons between the atomic force microscopy images reveal that the root-mean-square surface roughness of Fe films mediated by Pb and Bi surfactants are considerably smaller than those of the films mediated by Ag surfactant. The Auger electron spectra show that Pb and Bi segregate at the top of the surface. It has been concluded that Pb and Bi are effective surfactants for enhancing layer-by-layer growth in Fe homoepitaxy. Ag has the same effect, but it is less efficient due to the weak surface segregation of Ag

Hydrothermal synthesis and crystal structure of the Ni2(C4H4N2)(V4O12)(H2O)2 and Ni3(C4H4N2)3(V8O23) inorganic-organic hybrid compounds. Thermal, spectroscopic and magnetic studies of the hydrated phase

International Nuclear Information System (INIS)

Larrea, Edurne S.; Mesa, Jose L.; Pizarro, Jose L.; Arriortua, Maria I.; Rojo, Teofilo

2007-01-01

Ni 2 (C 4 H 4 N 2 )(V 4 O 12 )(H 2 O) 2 , 1, and Ni 3 (C 4 H 4 N 2 ) 3 (V 8 O 23 ), 2, have been synthesized using mild hydrothermal conditions at 170 deg. C under autogenous pressure. Both phases crystallize in the P-1 triclinic space group, with the unit-cell parameters, a=7.437(7), b=7.571(3), c=7.564(4) A, α=65.64(4), β=76.09(4), γ=86.25(3) o for 1 and a=8.566(2), b=9.117(2), c=12.619(3) A, α=71.05(2), β=83.48(4), γ=61.32(3) o for 2, being Z=2 for both compounds. The crystal structure of the three-dimensional 1 is constructed from layers linked between them through the pyrazine molecules. The sheets are formed by edge-shared [Ni 2 O 6 (H 2 O) 2 N 2 ] nickel(II) dimers octahedra and rings composed by four [V 4 O 12 ] vanadium(V) tetrahedra linked through vertices. The crystal structure of 2 is formed from vertex shared [VO 4 ] tetrahedra that give rise to twelve member rings. [NiO 4 (C 4 H 4 N 2 ) 2 ] ∞ chains, resulting from [NiO 4 N 2 ] octahedra and pyrazine molecules, give rise to a 3D skeleton when connecting to [VO 4 ] tetrahedra. Diffuse reflectance measurements of 1 indicate a slightly distorted octahedral geometry with values of Dq=880, B=980 and C=2700 cm -1 . Magnetic measurements of 1, carried out in the 5.0-300 K range, indicate the existence of antiferromagnetic couplings with a Neel temperature near to 38 K. - Graphical abstract: Crystal structure of a sheet of Ni 2 (C 4 H 4 N 2 )(V 4 O 12 )(H 2 O) 2

Synthesis and spectroscopic and structural characterization of the monomeric diborylphosphine and diphosphinoborane compounds PhP(BMes2)2 and MesB(PPh2)2 (Mes = 2,4,6-Me3C6H2)

International Nuclear Information System (INIS)

Bartlett, R.A.; Dias, H.V.R.; Power, P.P.

1988-01-01

The synthesis and spectroscopic and first x-ray structural characterization of a diborylphosphine, PhP(BMes 2 ) 2 (1), and a diphosphinoborane, MesB(PPh 2 ) 2 (2), are described. The structure of 1 has a planar core that involves the phosphorus and two boron atoms and also the five substituent carbons. In addition, the B-P bond lengths are shortened, which suggests a close structural analogy between 1 and the allyl cation. In the case of 2, although the boron remains planar, both phosphorus centers are pyramidal with slightly longer B-P bonds than in 1. Both 1 and 2 are the first examples of their respective classes of compound to be well characterized. Crystal data with Mo Kα radiation (λ = 0.71069 /angstrom/) at 130 K are as follows. 1: a = 14.302 (4) /angstrom/, b = 15.701 (3) /angstrom/, c = 16.601 (6) /angstrom/, β = 109.61 (2)/degrees/; monoclinic, space group C2/c, Z = 4, R = 0.059. 2: a = 7.815 (2) /angstrom/, b = 8.723 (2) /angstrom/, c = 40.147 (10) /angstrom/, β = 94.90 (2)/degrees/; monoclinic, space group P2 1 /n, Z = 4, R = 0.041. A listing of available 11 B and 31 P NMR data on compounds involving triply connected boron and phosphorus centers is also provided and discussed in the context of the data for 1 and 2. 25 references, 2 figures, 4 tables

Design and Discovery of Functionally Selective Serotonin 2C (5-HT2C) Receptor Agonists.

Science.gov (United States)

Cheng, Jianjun; McCorvy, John D; Giguere, Patrick M; Zhu, Hu; Kenakin, Terry; Roth, Bryan L; Kozikowski, Alan P

2016-11-10

On the basis of the structural similarity of our previous 5-HT 2C agonists with the melatonin receptor agonist tasimelteon and the putative biological cross-talk between serotonergic and melatonergic systems, a series of new (2,3-dihydro)benzofuran-based compounds were designed and synthesized. The compounds were evaluated for their selectivity toward 5-HT 2A , 5-HT 2B , and 5-HT 2C receptors in the calcium flux assay with the ultimate goal to generate selective 5-HT 2C agonists. Selected compounds were studied for their functional selectivity by comparing their transduction efficiency at the G protein signaling pathway versus β-arrestin recruitment. The most functionally selective compound (+)-7e produced weak β-arrestin recruitment and also demonstrated less receptor desensitization compared to serotonin in both calcium flux and phosphoinositide (PI) hydrolysis assays. We report for the first time that selective 5-HT 2C agonists possessing weak β-arrestin recruitment can produce distinct receptor desensitization properties.

Synthesis and characteristics of a novel 3-D organic amine oxalate: (enH2)1.5[Bi3(C2O4)6(CO2CONHCH2CH2NH3)].6.5H2O

International Nuclear Information System (INIS)

Yu Xiaohong; Zhang Hanhui; Cao Yanning; Chen Yiping; Wang Zhen

2006-01-01

A novel 3-D compound of (enH 2 ) 1.5 [Bi 3 (C 2 O 4 ) 6 (CO 2 CONHCH 2 CH 2 NH 3 )].6.5H 2 O has been hydrothermally synthesized and characterized by IR, ultraviolet-visible diffuse reflection integral spectrum (UV-Vis DRIS), fluorescence spectra, TGA and single crystal X-ray diffraction. It crystallizes in the monoclinic system, space group C2/c with a=31.110(8)A, b=11.544(3)A, c=22.583(6)A, β=112.419(3) o , V=7497(3)A 3 , Z=8, R 1 =0.0463 and wR 2 =0.1393 for unique 7686 reflections I>2σ(I). In the title compound, the Bi atoms have eight-fold and nine-fold coordination with respect to the oxygen atoms, with the Bi atoms in distorted dodecahedron and monocapped square antiprism, respectively. The 3-D framework of the title compound contains channels and is composed of linkages between Bi atoms and oxalate units, forming honeycomb-like layers with two kinds of 6+6 membered aperture, and pillared by oxalate ligands and monamide groups. The channels have N-ethylamine oxalate monamide group - CO 2 CONHCH 2 CH 2 NH 3 + , which is formed by the in situ reaction of en and oxalate acid. At room temperature, the complex exhibits intense blue luminescence with an emission peak at 445nm

Dependences of microstructure on electromagnetic interference shielding properties of nano-layered Ti3AlC2 ceramics.

Science.gov (United States)

Tan, Yongqiang; Luo, Heng; Zhou, Xiaosong; Peng, Shuming; Zhang, Haibin

2018-05-21

The microstructure dependent electromagnetic interference (EMI) shielding properties of nano-layered Ti 3 AlC 2 ceramics were presented in this study by comparing the shielding properties of various Ti 3 AlC 2 ceramics with distinct microstructures. Results indicate that Ti 3 AlC 2 ceramics with dense microstructure and coarse grains are more favourable for superior EMI shielding efficiency. High EMI shielding effectiveness over 40 dB at the whole Ku-band frequency range was achieved in Ti 3 AlC 2 ceramics by microstructure optimization, and the high shielding effectiveness were well maintained up to 600 °C. A further investigation reveals that only the absorption loss displays variations upon modifying microstructure by allowing more extensive multiple reflections in coarse layered grains. Moreover, the absorption loss of Ti 3 AlC 2 was found to be much higher than those of highly conductive TiC ceramics without layered structure. These results demonstrate that nano-layered MAX phase ceramics are promising candidates of high-temperature structural EMI shielding materials and provide insightful suggestions for achieving high EMI shielding efficiency in other ceramic-based shielding materials.

Recent Advances in Layered Ti3 C2 Tx MXene for Electrochemical Energy Storage.

Science.gov (United States)

Xiong, Dongbin; Li, Xifei; Bai, Zhimin; Lu, Shigang

2018-04-01

Ti 3 C 2 T x , a typical representative among the emerging family of 2D layered transition metal carbides and/or nitrides referred to as MXenes, has exhibited multiple advantages including metallic conductivity, a plastic layer structure, small band gaps, and the hydrophilic nature of its functionalized surface. As a result, this 2D material is intensively investigated for application in the energy storage field. The composition, morphology and texture, surface chemistry, and structural configuration of Ti 3 C 2 T x directly influence its electrochemical performance, e.g., the use of a well-designed 2D Ti 3 C 2 T x as a rechargeable battery anode has significantly enhanced battery performance by providing more chemically active interfaces, shortened ion-diffusion lengths, and improved in-plane carrier/charge-transport kinetics. Some recent progresses of Ti 3 C 2 T x MXene are achieved in energy storage. This Review summarizes recent advances in the synthesis and electrochemical energy storage applications of Ti 3 C 2 T x MXene including supercapacitors, lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries. The current opportunities and future challenges of Ti 3 C 2 T x MXene are addressed for energy-storage devices. This Review seeks to provide a rational and in-depth understanding of the relation between the electrochemical performance and the nanostructural/chemical composition of Ti 3 C 2 T x , which will promote the further development of 2D MXenes in energy-storage applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improved tribological properties of TiC with porous nanostructured TiO{sub 2} intermediate layer

Energy Technology Data Exchange (ETDEWEB)

Shanaghi, Ali, E-mail: alishanaghi@gmail.com [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Ahangarani, Shahrokh, E-mail: sh.ahangarani@gmail.com [Advanced Materials and Renewable Energies Department, Iranian Research Organization for Science and Technology, P.O. Box 15815-3538, Tehran (Iran, Islamic Republic of); Sabour Rouhaghdam, Ali Reza, E-mail: sabour01@modares.ac.ir [Surface Engineering Laboratory, Materials Engineering Department, Faculty of Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran (Iran, Islamic Republic of); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2011-12-15

Highlights: Black-Right-Pointing-Pointer The porous TiO{sub 2} nanoparticle coating is deposited as an intermediate layer on steel. Black-Right-Pointing-Pointer A homogenous and low friction TiC nanostructure coating is deposited by plasma CVD. Black-Right-Pointing-Pointer Intermediate layer can be determined the nucleation and growth of the TiC coating. Black-Right-Pointing-Pointer The porous interlayer improves the friction and wear of the TiC nanostructure coating. - Abstract: The mismatch in the thermal expansion coefficients between TiC coatings and steel substrates and residual stress in the TiC degrade the tribological properties. In this work, a porous nanostructured TiO{sub 2} coating is deposited as an intermediate layer on hot-work steel (H{sub 11}) before final deposition of the TiC film. This intermediate layer is expected to reduce the interfacial energy, decreases the thermal mismatch between TiC and steel, and improves the tribological properties. Grazing incidence X-ray diffraction (GIXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and pin-on-disk are used to study the structure as well as tribological properties such as friction, wear, and hardness. Our results reveal that the porous TiO{sub 2} interlayer improves the friction, wear, hardness, and elastic modulus of the system.

Dehydration of a layered double hydroxide-C2AH8

International Nuclear Information System (INIS)

Ukrainczyk, N.; Matusinovic, T.; Kurajica, S.; Zimmermann, B.; Sipusic, J.

2007-01-01

Thermal dehydration of dicalcium aluminate hydrate, C 2 AH 8 , has been investigated by simultaneous differential thermal and thermo gravimetric analysis (DTA/TGA), powder X-ray diffraction (XRD), temperature-dependent infrared spectroscopy (FT-IR), and BET method of surface area measurement. The temperature-dependent infrared measurements were studied by two-dimensional infrared (2D-IR) correlation spectroscopy. The structure of aluminum-oxide polyhedron, characterized by 27 Al solid state NMR spectrum method and FT-IR, shows tetrahedron and octahedron as the main forms of aluminum-oxide polyhedrons in C 2 AH 8 sample. From the results obtained a variety of structural transformations observed are explained as a consequence of the removal of loosely held interlayer water molecules at lower temperatures, followed by grafting process of the interlayer [Al(OH) 4 ] - anion. Structural model of a grafting process of the interlayer [Al(OH) 4 ] - tetrahedron onto hydroxylated octahedrons of [Ca 2 Al(OH) 6 ] + layers has been proposed in order to explain observed loss of one water molecule, shrinkage of interlayer spacing and qualitative changes of FT-IR spectra. At higher temperatures the dehydroxylation of the lattice and decomposition of the interlayer species occurs, yielding amorphous material that crystallizes into C 3 A and C 12 A 7 at 885 deg. C. Those findings provide improvement in the interpretation of thermo-analytical results of calcium aluminate cements (CAC) hydration products, and better understanding of CAC conversion process

Crystal structures of two 1:2 dihydrate compounds of chloranilic acid with 2-carboxypyridine and 2-carboxyquinoline

Directory of Open Access Journals (Sweden)

Kazuma Gotoh

2017-12-01

Full Text Available The crystal structure of the 1:2 dihydrate compound of chloranilic acid (systematic name: 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone with 2-carboxypyridine (another common name: picolinic acid; systematic name: pyridine-2-carboxylic acid, namely, 2C6H5.5NO20.5+·C6HCl2O4−·2H2O, (I, has been determined at 180 K, and the structure of the 1:2 dihydrate compound of chloranilic acid with 2-carboxyquinoline (another common name: quinaldic acid; systematic name: quinoline-2-carboxylic acid, namely, 2C10H7NO2·C6H2Cl2O4·2H2O, (II, has been redetermined at 200 K. This determination presents a higher precision crystal structure than the previously published structure [Marfo-Owusu & Thompson (2014. X-ray Struct. Anal. Online, 30, 55–56]. Compound (I was analysed as a disordered structure over two states, viz. salt and co-crystal. The salt is bis(2-carboxypyridinium chloranilate dihydrate, 2C6H6NO2+·C6Cl2O42−·2H2O, and the co-crystal is bis(pyridinium-2-carboxylate chloranilic acid dihydrate, 2C6H5NO2·C6H2Cl2O4·2H2O, including zwitterionic 2-carboxypyridine. In both salt and co-crystal, the water molecule links the chloranilic acid and 2-carboxypyridine molecules through O—H...O and N—H...O hydrogen bonds. The 2-carboxypyridine molecules are connected into a head-to-head inversion dimer by a short O—H...O hydrogen bond, in which the H atom is disordered over two positions. Compound (II is a 1:2 dihydrate co-crystal of chloranilic acid and zwitterionic 2-carboxyquinoline. The water molecule links the chloranilic acid and 2-carboxyquinoline molecules through O—H...O hydrogen bonds. The 2-carboxyquinoline molecules are connected into a head-to-tail inversion dimer by a pair of N—H...O hydrogen bonds.

Wear Behavior of Cold Pressed and Sintered Al2O3/TiC/CaF2Al2O3/TiC Laminated Ceramic Composite

Institute of Scientific and Technical Information of China (English)

Xuefeng YANG; Jian CHENG; Peilong SONG; Shouren WANG; Liying YANG; Yanjun WANG; Ken MAO

2013-01-01

A novel laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance,such as low friction coefficient and low wear rate.Al2O3/TiC/CaF2 and Al2O3/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure.Solid lubricant CaF2 was added evenly into the Al2O3/TiC/CaF2 layer to reduce the friction and wear.Al2O3/TiC ceramic was also cold pressed and sintered for comparison.Friction analysis of the two ceramics was then conducted via a wear-and-tear machine.Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum,respectively.Results showed that the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al2O3/TiC ceramic alone because of the addition of CaF2 into the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite.Under the friction load,the tiny CaF2 particles were scraped from the Al2O3/TiC/CaF2 layer and spread on friction pairs before falling off into micropits.This process formed a smooth,self-lubricating film,which led to better anti-wear properties.Adhesive wear is the main wear mechanism of Al2O3/TiC/CaF2 layer and abrasive wear is the main wear mechanism of Al2O3/TiC layer.

Pressure effects on the magnetic behaviour of copper (II) compounds: magnetic ordering of layered organic/inorganic magnets

International Nuclear Information System (INIS)

Levchenko, G; Varyukhin, V N; Berezhnaya, L V; Rusakov, V F

2012-01-01

The high hydrostatic pressure effect on the magnetic properties of the layered hybrid compounds Cu 2 (OH) 3 (C n H 2n+1 CO 2 )⋅mH 2 O with distance between magnetic layers of up to 40 Å is studied. It is shown that the temperature of the ferromagnetic ordering decreases linearly with pressure increase. From measurements of susceptibility in the paramagnetic region, using both quantum Heisenberg and Ising exchange coupling models in layers and dipole interaction between layers, the in- and interlayer interactions are deduced. The dipole interactions are calculated and are shown to coincide with the model of Ising interactions in the layers. The value and decrease of T c under pressure are mainly driven by the value and decrease of the in-plane interactions. The formation of the long range ordering in the layered sample with dipolar interaction between layers is analysed. As a conclusion it is suggested that for designing high temperature ferromagnetism in layer compounds it is enough to have large in-plane interactions of ions with specific symmetry in layers and weak dipole interactions between layers. (paper)

[H3N(CH2)4NH3]2[Al4(C2O4)(H2PO4)2(PO4)4].4[H2O]: A new layered aluminum phosphate-oxalate

International Nuclear Information System (INIS)

Peng Li; Li Jiyang; Yu Jihong; Li Guanghua; Fang Qianrong; Xu Ruren

2005-01-01

A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H 3 N(CH 2 ) 4 NH 3 ] 2 [Al 4 (C 2 O 4 )(H 2 PO 4 ) 2 (PO 4 ) 4 ].4[H 2 O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, 31 P MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a=8.0484(7) A, b=8.8608(8) A, c=13.2224(11) A, α=80.830(6) deg. , β=74.965(5) deg. , γ=78.782(6) deg. , Z=2, R 1[ I >2 σ ( I )] =0.0511 and wR 2(alldata) =0.1423. The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. -- Graphical abstract: The alternation of AlO 4 tetrahedra and PO 4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO 6 octahedra to form the layered structure with 4,6-net sheet. Oxalate ions are bis-bidentately boned by participating in the coordination of AlO 6 , and bridging the adjacent AlO 6 octahedra

The coloring problem in the solid-state metal boride carbide ScB{sub 2}C{sub 2}. A theoretical analysis

Energy Technology Data Exchange (ETDEWEB)

Lassoued, Souheila [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Boucher, Benoit [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques; Max-Planck-Institut fuer Chemische Physik Fester Stoffe, Dresden (Germany); Boutarfaia, Ahmed [Universite Kasdi Merbah-Ouargla (Algeria). Faculte des Mathematiques et des Sciences de la Matiere; Gautier, Regis; Halet, Jean-Francois [Universite de Rennes, Ecole Nationale Superieure de Chimie, UMR 6226 CNRS (France). Inst. des Sciences Chimiques

2016-08-01

The electronic properties of the layered ternary metal boride carbide ScB{sub 2}C{sub 2}, the structure of which consists of B/C layers made of fused five- and seven-membered rings alternating with scandium sheets, are analyzed. In particular, the respective positions of the B and C atoms (the so-called coloring problem) are tackled using density functional theory, quantum theory of atoms in molecules, and electron localizability indicator calculations. Results reveal that (i) the most stable coloring minimizes the number of B-B and C-C contacts and maximizes the number of boron atoms in the heptagons, (ii) the compound is metallic in character, and (iii) rather important covalent bonding occurs between the metallic sheets and the boron-carbon network.

Synthesis and biological evaluation of 4-(2-fluorophenoxy)-3,3'-bipyridine derivatives as potential c-met inhibitors.

Science.gov (United States)

Zhao, Sijia; Zhang, Yu; Zhou, Hongyang; Xi, Shuancheng; Zou, Bin; Bao, Guanglong; Wang, Limei; Wang, Jiao; Zeng, Tianfang; Gong, Ping; Zhai, Xin

2016-09-14

Six series of novel 4-(2-fluorophenoxy)-3,3'-bipyridine derivatives conjugated with aza-aryl formamide/amine scaffords were designed and synthesized through a structure-based molecular hybridization approach. The target compounds were evaluated for c-Met kinase inhibitory activities and cytotoxicity against four cancer cell lines (HT-29, A549, MKN-45 and MDA-MB-231) in vitro. Most compounds exhibited moderate to excellent potency, and the most promising candidate 26c (c-Met kinase IC50 = 8.2 nM) showed a 4.7-fold increase in cytotoxicity against c-Met-addicted MKN-45 cell line in vitro (IC50 = 3 nM), superior to that of Foretinib (IC50 = 23 nM). The preliminary structure-activity relationship indicated that a 1H-benzo [e] [1,3,4]thiadiazine-3-carboxamide-4,4-dioxide moiety as linker contributed to the antitumor potency. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Electronic structure of the misfit layer compound (SnS)(1.20)TiS2 : Band structure calculations and photoelectron spectra

NARCIS (Netherlands)

Fang, CM; deGroot, RA; Wiegers, GA; Haas, C

1996-01-01

In order to understand the electronic structure of the incommensurate misfit layer compound (SnS)(1.20)TiS2 we carried out an ab initio band structure calculation in the supercell approximation. The band structure is compared with that of the components 1T-TiS2 and hypothetical SnS with a similar

Electronic structure of the misfit layer compound (SnS)1.20TiS2 : band structure calculations and photoelectron spectra

NARCIS (Netherlands)

Fang, C.M.; Groot, R.A. de; Wiegers, G.A.; Haas, C.

1996-01-01

In order to understand the electronic structure of the incommensurate misfit layer compound (SnS)1.20TiS2 we carried out an ab initio band structure calculation in the supercell approximation. The band structure is compared with that of the components 1T-TiS2 and hypothetical SnS with a similar

New Approaches for the Synthesis, Cytotoxicity and Toxicity of Heterocyclic Compounds Derived from 2-Cyanomethylbenzo[c]imidazole.

Science.gov (United States)

Mohareb, Rafat M; Mohamed, Abeer A; Abdallah, Amira E M

2016-01-01

The reaction of ethyl cyanoacetate with o-phenylenediamine gave the 2-cyanomethylbenzo[c]imidazole (1). The latter compound was used as the key starting material to synthesise biologically active heterocyclic derivatives. Thus, the reaction of 1 with cyclohexanone and either of benzaldehyde, 4-methoxybenzaldehyde or 4-chlorobenzaldehyde gave the annulated derivatives 2a-c, respectively. The antitumor evaluations of the newly synthesized products against the three cancer cell lines MCF-7 (breast adeno-carcinoma), NCI-H460 (non-small cell lung cancer) and SF-268 (CNS cancer) showed that compounds 2b, 6, 11b, 11c, 12b, 16a, 16b and 18a exhibited optimal cytotoxic effect against cancer cell lines, with IC50 values in the nM range. Bioactive compounds are often toxic to shrimp larvae. Thus, in order to monitor these chemicals in vivo lethality to shrimp larvae (Artemia salina), Brine-Shrimp Lethality Assay was used. Compounds 11b, 12b and 16b showed no toxicity against the tested organisms.

Fused Heterocyclic Compounds as Potent Indoleamine-2,3-dioxygenase 1 Inhibitors.

Science.gov (United States)

Panda, Subhankar; Roy, Ashalata; Deka, Suman Jyoti; Trivedi, Vishal; Manna, Debasis

2016-12-08

Uncontrolled metabolism of l-tryptophan (l-Trp) in the immune system has been recognized as a critical cellular process in immune tolerance. Indoleamine 2,3-dioxygenase 1 (IDO1) enzyme plays an important role in the metabolism of a local l-Trp through the kynurenine pathway in the immune systems. In this regard, IDO1 has emerged as a therapeutic target for the treatment of diseases that are associated with immune suppression like chronic infections, cancer, and others. In this study, we synthesized a series of pyridopyrimidine, pyrazolopyranopyrimidine, and dipyrazolopyran derivatives. Further lead optimizations directed to the identification of potent compounds, 4j and 4l (IC 50 = 260 and 151 nM, respectively). These compounds also exhibited IDO1 inhibitory activities in the low nanomolar range in MDA-MB-231 cells with very low cytotoxicity. Stronger selectivity for the IDO1 enzyme (>300-fold) over tryptophan 2,3-dioxygenase (TDO) enzyme was also observed for these compounds. Hence, these fused heterocyclic compounds are attractive candidates for the advanced study of IDO1-dependent cellular function and immunotherapeutic applications.

Pressure induced magneto-structural phase transitions in layered RMn2X2 compounds (invited)

International Nuclear Information System (INIS)

Kennedy, Shane; Wang, Jianli; Campbell, Stewart; Hofmann, Michael; Dou, Shixue

2014-01-01

We have studied a range of pseudo-ternaries derived from the parent compound PrMn 2 Ge 2 , substituting for each constituent element with a smaller one to contract the lattice. This enables us to observe the magneto-elastic transitions that occur as the Mn-Mn nearest neighbour distance is reduced and to assess the role of Pr on the magnetism. Here, we report on the PrMn 2 Ge 2−x Si x , Pr 1−x Y x Mn 2 Ge 2 , and PrMn 2−x Fe x Ge 2 systems. The pressure produced by chemical substitution in these pseudo-ternaries is inherently non-uniform, with local pressure variations dependent on the local atomic distribution. We find that concentrated chemical substitution on the R or X site (e.g., in Pr 0.5 Y 0.5 Mn 2 Ge 2 and PrMn 2 Ge 0.8 Si 1.2 ) can produce a separation into two distinct magnetic phases, canted ferromagnetic and canted antiferromagnetic, with a commensurate phase gap in the crystalline lattice. This phase gap is a consequence of the combination of phase separation and spontaneous magnetostriction, which is positive on transition to the canted ferromagnetic phase and negative on transition to the canted antiferromagnetic phase. Our results show that co-existence of canted ferromagnetic and antiferromagnetic phases depends on chemical pressure from the rare earth and metalloid sites, on local lattice strain distributions and on applied magnetic field. We demonstrate that the effects of chemical pressure bear close resemblance to those of mechanical pressure on the parent compound

Crystal structure of the Ce2Ni2Zn15 compound

International Nuclear Information System (INIS)

Opainich, I.M.; Pavlyuk, V.V.; Bodak, O.I.; Cherny, R.; Yvon, K.

1996-01-01

A structure of a new ternary compound of the composition Ce2Ni2Zn15 (sp.gr.R3-barm,a=0.9080(3) nm, c=1.3294(3) nm) was determined on single-crystal and powder specimens. The study was performed on a Philips PW1100 automatic diffractometer and a DRON-4.07 powder diffractometer. The Ce2Ni2Zn15 compound is crystallized in the Ce2Al2Co15 structure type with the aluminum positions being occupied by nickel and cobalt positions being occupied by zinc

Polyethers containing 4-(carbazol-2-yl)-7-arylbenzo[c]-1,2,5-thiadiazole chromophores as solution processed materials for hole transporting layers of OLEDs

Science.gov (United States)

Krucaite, G.; Tavgeniene, D.; Xie, Z.; Lin, X.; Zhang, B.; Grigalevicius, S.

2018-02-01

Two polyethers containing electroactive pendent 4-(carbazol-2-yl)-7-arylbenzo[c]-1,2,5-thiadiazole moieties have been synthesized by the multi-step synthetic route. Full characterization of their structures is presented. The polymers represent derivatives of very high thermal stability with initial thermal degradation temperatures of 425 °C and 431 °C. Glass transition temperatures of the amorphous materials were also very high and reached values of 154 °C and 163 °C. The electron photoemission spectra of thin layers of the polymers showed ionization potentials of 5.84 eV and 5.93 eV. Hole-transporting properties of the polymeric materials were tested in the structures of organic light emitting diodes with Alq3 as the green emitter and electron transporting material. An electroluminescent device containing hole-transporting layer (HTL) of the polymer with electroactive 4-carbazolyl-7-phenylbenzo[c]-1,2,5-thiadiazole moieties exhibited turn on voltage of 6.2 V, maximum photometric efficiency of 2.5 cd/A and maximum brightness exceeding 300 cd/m2. The device containing HTL of the polymer with 4-carbazolyl-7-(1-naphtyl)benzo[c]-1,2,5-thiadiazole moieties demonstrated turn on voltage of 5.2 V, maximum photometric efficiency of 1.6 cd/A and maximum brightness exceeding 1500 cd/m2. The efficiencies were about 30-90% higher than that of the device containing widely used hole transporting layers of poly(9-vinylcarbazole).

Low temperature (100 °C) atomic layer deposited-ZrO2 for recessed gate GaN HEMTs on Si

Science.gov (United States)

Byun, Young-Chul; Lee, Jae-Gil; Meng, Xin; Lee, Joy S.; Lucero, Antonio T.; Kim, Si Joon; Young, Chadwin D.; Kim, Moon J.; Kim, Jiyoung

2017-08-01

In this paper, the effect of atomic layer deposited ZrO2 gate dielectrics, deposited at low temperature (100 °C), on the characteristics of recessed-gate High Electron Mobility Transistors (HEMTs) on Al0.25Ga0.75N/GaN/Si is investigated and compared with the characteristics of those with ZrO2 films deposited at typical atomic layer deposited (ALD) process temperatures (250 °C). Negligible hysteresis (ΔVth 4 V), and low interfacial state density (Dit = 3.69 × 1011 eV-1 cm-2) were observed on recessed gate HEMTs with ˜5 nm ALD-ZrO2 films grown at 100 °C. The excellent properties of recessed gate HEMTs are due to the absence of an interfacial layer and an amorphous phase of the film. An interfacial layer between 250 °C-ZrO2 and GaN is observed via high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. However, 100 °C-ZrO2 and GaN shows no significant interfacial layer formation. Moreover, while 100 °C-ZrO2 films maintain an amorphous phase on either substrate (GaN and Si), 250 °C-ZrO2 films exhibit a polycrystalline-phase when deposited on GaN and an amorphous phase when deposited on Si. Contrary to popular belief, the low-temperature ALD process for ZrO2 results in excellent HEMT performance.

Requirement of carbon dioxide for initial growth of facultative methylotroph, Acidomonas methanolica MB58.

Science.gov (United States)

Mitsui, Ryoji; Katayama, Hiroko; Tanaka, Mitsuo

2015-07-01

The facultative methylotrophic bacterium Acidomonas methanolica MB58 can utilize C1 compounds via the ribulose monophosphate pathway. A large gene cluster comprising three components related to C1 metabolism was found in the genome. From upstream, the first was an mxa cluster encoding proteins for oxidation of methanol to formaldehyde; the second was the rmp cluster encoding enzymes for formaldehyde fixation; and the third was the cbb gene cluster encoding proteins for carbon dioxide (CO2) fixation. Examination of CO2 requirements for growth of A. methanolica MB58 cells demonstrated that it did not grow on any carbon source under CO2-free conditions. Measurement of ribulose-1,5-bisphosphate carboxylase activity and RT-PCR analysis demonstrated enzymatic activity was detected in A. methanolica MB58 at growth phase, regardless of carbon sources. However, methanol dehydrogenase and 3-hexlose-6-phosphate synthase expression was regulated by methanol or formaldehyde; it were detected during growth and apparently differed from ribulose-1,5-bisphosphate carboxylase expression. These results suggested that A. methanolica MB58 may be initially dependent on autotrophic growth and that carbon assimilation was subsequently coupled with the ribulose monophosphate pathway at early- to mid-log phases during methylotrophic growth. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Aspects of transmetallation reactions of 2-Me2NCH2C6H4- and 2,6-(Me2NCH2)-C6H3-metal (Pd,Pt,Hg,Tl) complexes with metal carboxylates and low-valent metal (Pd,Pt) complexes

NARCIS (Netherlands)

Koten, G. van; Ploeg, A.F.M.J. van der; Vrieze, K.

1981-01-01

A study has been made of reactions involving organometallic compounds containing ortho-Me{2}NCH{2} substituted aryl ligands. The single step syntheses of the new compounds [(2-Me{2}NCH{2}C{6}H{4}){2}TlCl], [ [{(S)-2-Me{2}NCH(Me)C{6}H{4}}{2}TlCl], [{(S)-2-Me{2}NCH(Me)C{6}H{4}}TlCl{2}], [{2,

Neutron scattering investigation of layer-bending modes in alkali-metal--graphite intercalation compounds

International Nuclear Information System (INIS)

Zabel, H.; Kamitakahara, W.A.; Nicklow, R.M.

1982-01-01

Phonon dispersion curves for low-frequency transverse modes propagating in the basal plane have been measured in the alkali-metal--graphite intercalation compounds KC 8 , CsC 8 , KC 24 , and RbC 24 by means of neutron spectroscopy. The acoustic branches show an almost quadratic dispersion relation at small q, characteristic of strongly layered materials. The optical branches of stage-1 compounds can be classified as either graphitelike branches showing dispersion, or as almost dispersionless alkali-metal-like modes. Macroscopic shear constants C 44 and layer-bending moduli have been obtained for the intercalation compounds by analyzing the data in terms of a simple semicontinuum model. In stage-2 compounds, a dramatic softening of the shear constant by about a factor of 8 compared with pure graphite has been observed. Low-temperature results on KC 24 indicate the opening of a frequency gap near the alkali-metal Brillouin-zone boundary, possibly due to the formation of the alkali-metal superstructure

The MB2 gene family of Plasmodium species has a unique combination of S1 and GTP-binding domains

Directory of Open Access Journals (Sweden)

Ogunjumo Oluwasanmi

2004-06-01

Full Text Available Abstract Background Identification and characterization of novel Plasmodium gene families is necessary for developing new anti-malarial therapeutics. The products of the Plasmodium falciparum gene, MB2, were shown previously to have a stage-specific pattern of subcellular localization and proteolytic processing. Results Genes homologous to MB2 were identified in five additional parasite species, P. knowlesi, P. gallinaceum, P. berghei, P. yoelii, and P. chabaudi. Sequence comparisons among the MB2 gene products reveal amino acid conservation of structural features, including putative S1 and GTP-binding domains, and putative signal peptides and nuclear localization signals. Conclusions The combination of domains is unique to this gene family and indicates that MB2 genes comprise a novel family and therefore may be a good target for drug development.

The MB2 gene family of Plasmodium species has a unique combination of S1 and GTP-binding domains

Science.gov (United States)

Romero, Lisa C; Nguyen, Thanh V; Deville, Benoit; Ogunjumo, Oluwasanmi; James, Anthony A

2004-01-01

Background Identification and characterization of novel Plasmodium gene families is necessary for developing new anti-malarial therapeutics. The products of the Plasmodium falciparum gene, MB2, were shown previously to have a stage-specific pattern of subcellular localization and proteolytic processing. Results Genes homologous to MB2 were identified in five additional parasite species, P. knowlesi, P. gallinaceum, P. berghei, P. yoelii, and P. chabaudi. Sequence comparisons among the MB2 gene products reveal amino acid conservation of structural features, including putative S1 and GTP-binding domains, and putative signal peptides and nuclear localization signals. Conclusions The combination of domains is unique to this gene family and indicates that MB2 genes comprise a novel family and therefore may be a good target for drug development. PMID:15222903

CREATINE PHOSPHOKINASE ISOENZYME-MB MASS (CK-MB MASS AND TROPONIN I (cTnI IN DOGS (Canis familiaris

Directory of Open Access Journals (Sweden)

Millena Vidal Freitas

2015-07-01

Full Text Available Cardiac markers, especially CK-MB mass and cTnI, have an essential role in both human and veterinary clinical and surgical cardiology, allowing a more precise and accurate diagnosis in myocardial lesions. The goal of this work was to measure these cardiac markers in veterinary medicine, improve their use and provide information about these laboratory methods that allow non-invasive health monitoring of the myocardial cell. Parameters quantification was obtained from sera of healthy dogs examined during routine procedures at the Small Animal Veterinary Hospital of Universidade Estadual do Norte Fluminense Darcy Ribeiro. The human chemiluminescence essay turbo kit (IMMULITE Turbo, Siemens ® test proved to be effective in canine species for both CK-MB mass and cTnI. In addition, the values found for CK-MB will significantly contribute to clinical routine or experimental work with dogs.

A novel inorganic-organic compound: Synthesis and structural characterization of tin(II) phenylbis(phosphonate), Sn2(PO3C6H4PO3)

International Nuclear Information System (INIS)

Subbiah, Ayyappan; Bhuvanesh, Nattamai; Clearfield, Abraham

2005-01-01

A novel tin(II) phenylbis(phosphonate) compound has been synthesized hydrothermally and its structure has been determined by single crystal X-ray diffraction. The structure is monoclinic, space group P2 1 /c (no. 14), a=4.8094(4), b=16.2871(13), c=6.9107(6)A; β=106.292(6) o , V=519.59(7)A 3 , Z=2. The three-dimensional structure consists of 3-coordinated tin and 4-coordinated phosphorus double layers separated (pillared) by phenyl rings. These phenyl rings are placed 4.8A apart along the a-axis in the structure resulting in lower surface area (∼14m 2 /g). The porosity has been increased by replacing phenyl groups by methyl groups (∼31m 2 /g)

Electronic and electrochemical properties of platinum(II) and platinum-mercury-carboxylato complexes containing 2-Me2NCH2C6H4, 2,6-(Me2NCH2)2C6H3- and 2-Me2NC6H4CH2 - ligands

NARCIS (Netherlands)

Koten, G. van; Ploeg, A.F.M.J. van der; Schmitz, J.E.J.; Linden, J.G.M. van der

1982-01-01

The organoplatinum(II) compounds [{2, 6-(Me{2}NCH{2}){2}C{6}H{3}}PtBr] and cis-[(C-N){2}Pt] (C-N = 2-Me{2}NCH{2}C{6}H{4}, 2-Me{2}NC{6}H{4}CH{2}) can be chemically irreversibly oxidized in the potential range 1.00 to 1.35 V vs. an Ag/AgCl electrode, whereas the organoplatinum@?mercury complexes

Photoluminescence enhancement in porous SiC passivated by atomic layer deposited Al2O3 films

DEFF Research Database (Denmark)

Lu, Weifang; Iwasa, Yoshimi; Ou, Yiyu

2016-01-01

Porous SiC co-doped with B and N was passivated by atomic layer deposited (ALD) Al2O3 films to enhance the photoluminescence. After optimizing the deposition conditions, as high as 14.9 times photoluminescence enhancement has been achieved.......Porous SiC co-doped with B and N was passivated by atomic layer deposited (ALD) Al2O3 films to enhance the photoluminescence. After optimizing the deposition conditions, as high as 14.9 times photoluminescence enhancement has been achieved....

Synthesis by two methods and crystal structure determination of a new pyrochlore-related compound Sm{sub 2}FeTaO{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Torres-Martinez, Leticia M., E-mail: lettorresg@yahoo.com [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Ruiz-Gomez, Miguel A. [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P. 78290 (Mexico); Figueroa-Torres, M.Z.; Juarez-Ramirez, Isaias [Departamento de Ecomateriales y Energia, Facultad de Ingenieria Civil, Universidad Autonoma de Nuevo Leon, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Moctezuma, Edgar [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P. 78290 (Mexico); and others

2012-04-16

Graphical abstract: The monoclinic (space group C2/c) structure of a new compound, Sm{sub 2}FeTaO{sub 7} shows an alternating Sm-O and Fe/Ta-O layers. In the Fe/Ta-O layer, Fe/Ta1 and Fe/Ta3 cations are coordinated by six oxygen atoms, forming irregular octahedral interconnected into a hexagonal tungsten bronze (HTB) type network. The HTB layer is a fundamental framework in the pyrohlore-related structure. Highlights: Black-Right-Pointing-Pointer Pyrochlore-related compound Sm{sub 2}FeTaO{sub 7} prepared by solid state reaction and sol-gel. Black-Right-Pointing-Pointer Sm{sub 2}FeTaO{sub 7} crystallizes with a monoclinic crystal structure and space group C2/c. Black-Right-Pointing-Pointer The compound is synthesized by sol-gel at lower temperature and time than solid state. Black-Right-Pointing-Pointer Surface area of sol-gel Sm{sub 2}FeTaO{sub 7} is 10 times higher than that prepared by solid state. - Abstract: This paper reports on the synthesis of a new pyrochlore-related compound Sm{sub 2}FeTaO{sub 7} by both solid state reaction and sol-gel synthesis routes. Structural features were determined by X-ray powder diffraction and Rietveld refinement and were corroborated using Transmission Electron Microscopy (TEM). The results revealed that Sm{sub 2}FeTaO{sub 7} crystallized in the monoclinic system with space group C2/c and the following cell parameters: a = 13.1307(5) Angstrom-Sign , b = 7.5854(3) Angstrom-Sign , c = 11.6425(4) Angstrom-Sign and {beta} = 100.971(2) Degree-Sign . The monoclinic structure of Sm{sub 2}FeTaO{sub 7} showed an arrangement of alternating Sm-O and Fe/Ta-O layers and two types of irregular octahedra of Fe/Ta-O, which are interconnected into a hexagonal tungsten bronze (HTB)-type network. On the other hand, Sm{sub 2}FeTaO{sub 7} prepared by sol-gel was obtained with lower particle sizes than the solid state produced compound. The difference in particle size causes a difference of one order of magnitude in the specific surface area. In

Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB_2 powders

International Nuclear Information System (INIS)

Diao, Yunhua; Zhang, Kemin

2015-01-01

Highlights: • A TiC/TiB_2 composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB_2 powders. • A maximum hardness of 1100 HV was achieved in the laser clad TiC/TiB_2 composite layer. • Corrosion resistance of the TC2 alloy in NaCl (3.5 wt%) aqueous solution can be improved after laser cladding. - Abstract: In the present work, a TiC/TiB_2 composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB_2 powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB_2. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB_2 intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens’ corrosion property is clearly becoming better than that of the substrate.

Crystal structure and spectroscopic analysis of a new oxalate-bridged MnII compound: catena-poly[guanidinium [[aquachloridomanganese(II]-μ2-oxalato-κ4O1,O2:O1′,O2′] monohydrate

Directory of Open Access Journals (Sweden)

Hiba Sehimi

2016-05-01

Full Text Available As part of our studies on the synthesis and the characterization of oxalate-bridged compounds M–ox–M (ox = oxalate dianion and M = transition metal ion, we report the crystal structure of a new oxalate-bridged MnII phase, {(CH6N3[Mn(C2O4Cl(H2O]·H2O}n. In the compound, a succession of MnII ions (situated on inversion centers adopting a distorted octahedral coordination and bridged by oxalate ligands forms parallel zigzag chains running along the c axis. These chains are interconnected through O—H...O hydrogen-bonding interactions to form anionic layers parallel to (010. Individual layers are held together via strong hydrogen bonds involving the guanidinium cations (N—H...O and N—H...Cl and the disordered non-coordinating water molecule (O—H...O and O—H...Cl, as well as by guanidinium π–π stacking. The structural data were confirmed by IR and UV–Visible spectroscopic analysis.

An ab initio investigation of vibrational, thermodynamic, and optical properties of Sc2AlC MAX compound

International Nuclear Information System (INIS)

Ali, M A; Nasir, M T; Khatun, M R; Naqib, S H; Islam, A K M A

2016-01-01

The structural vibrational, thermodynamical, and optical properties of potentially technologically important, weakly coupled MAX compound, Sc 2 AlC are calculated using density functional theory (DFT). The structural properties of Sc 2 AlC are compared with the results reported earlier. The vibrational, thermodynamical, and optical properties are theoretically estimated for the first time. The phonon dispersion curve is calculated and the dynamical stability of this compound is investigated. The optical and acoustic modes are observed clearly. We calculate the Helmholtz free energy ( F ), internal energy ( E ), entropy ( S ), and specific heat capacity ( C v ) from the phonon density of states. Various optical parameters are also calculated. The reflectance spectrum shows that this compound has the potential to be used as an efficient solar reflector. (paper)

Oxyfluoride Chemistry of Layered Perovskite Compounds

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Yoshihiro Tsujimoto

2012-03-01

Full Text Available In this paper, we review recent progress and new challenges in the area of oxyfluoride perovskite, especially layered systems including Ruddlesden-Popper (RP, Dion-Jacobson (DJ and Aurivillius (AV type perovskite families. It is difficult to synthesize oxyfluoride perovskite using a conventional solid-state reaction because of the high chemical stability of the simple fluoride starting materials. Nevertheless, persistent efforts made by solid-state chemists have led to a major breakthrough in stabilizing such a mixed anion system. In particular, it is known that layered perovskite compounds exhibit a rich variety of O/F site occupation according to the synthesis used. We also present the synthetic strategies to further extend RP type perovskite compounds, with particular reference to newly synthesized oxyfluorides, Sr2CoO3F and Sr3Fe2O5+xF2−x (x ~ 0.44.

Slow relaxation of the magnetization observed in an antiferromagnetically ordered phase for SCM-based two-dimensional layered compounds.

Science.gov (United States)

Kagesawa, Koichi; Nishimura, Yuki; Yoshida, Hiroki; Breedlove, Brian K; Yamashita, Masahiro; Miyasaka, Hitoshi

2017-03-07

Two-dimensional layered compounds with different counteranions, [{Mn(salen)} 4 C6](BF 4 ) 2 ·2(CH 3 OH) (1) and [{Mn(salen)} 4 C6](PF 6 ) 2 ·2(CH 3 OH) (2) (salen 2- = N,N'-bis(salicylideneiminato), C6 2- = C 6 H 12 (COO) 2 2- ), were synthesized by assembling [Mn(salen)(H 2 O)]X (X - = BF 4 - and PF 6 - ) and C 6 H 12 (CO 2 - ) 2 (C6 2- ) in a methanol/2-propanol medium. The compounds have similar structures, which are composed of Mn(salen) out-of-plane dimers bridged by μ 4 -type C6 2- ions, forming a brick-wall-type network of [-{Mn 2 }-OCO-] chains alternately connected via C 6 H 12 linkers of C6 2- moieties. The counteranions for 1 and 2, i.e., BF 4 - and PF 6 - , respectively, are located between layers. Since the size of BF 4 - is smaller than that of PF 6 - , intra-layer inter-chain and inter-plane nearest-neighbor MnMn distances are shorter in 1 than in 2. The zigzag chain moiety of [-{Mn 2 }-OCO-] leads to a canted S = 2 spin arrangement with ferromagnetic coupling in the Mn III out-of-plane dimer moiety and antiferromagnetic coupling through -OCO- bridges. Due to strong uniaxial anisotropy of the Mn III ion, the [-{Mn 2 }-OCO-] chains could behave as a single-chain magnet (SCM), which exhibits slow relaxation of magnetization at low temperatures. Nevertheless, these compounds fall into an antiferromagnetic ground state at higher temperatures of T N = 4.6 and 3.8 K for 1 and 2, respectively, than active temperatures for SCM behavior. The spin flip field at 1.8 K is 2.7 and 1.8 kOe for 1 and 2, respectively, which is attributed to the inter-chain interactions tuned by the size of the counteranions. The relaxation times of magnetization become longer at the boundary between the antiferromagnetic phase and the paramagnetic phase.

Magnetic and Electrical Transport Properties of Dirac Compound BaMnSb2*

Science.gov (United States)

Huang, Silu; Kim, Jisun; Shelton, William. A.; Plummer, Ward; Jin, Rongying

BaMnSb2 is a layered compound containing Sb square nets that is theoretically predicted to host Dirac fermions. We have carried out experimental investigations on electrical transport and magnetic properties of BaMnSb2 single crystals. Both in-plane (ρab) and c-axis (ρc) resistivities show metallic behavior with a small bump in ρc located near 40 K, while there is large anisotropy ρc / ρab ( 100 at 300 K) that increases with decreasing temperature to 1500 at 2 K. Interestingly, Shubnikov-de Hass (SdH) oscillations are observed for both ρab and ρc over a wide temperature and magnetic field range. Quantitative analysis indicates that large amplitude SdH oscillations result from nearly massless Dirac Fermions. Furthermore, our magnetic measurements indicate an A-type antiferromagnetic magnetic ordering below 286 K where ferromagnetic ordering is observed in the ab plane with antiferromagnetic coupling along the c direction. These results indicate that BaMnSb2 is a 2D magnetic Dirac material. This work is supported by NSF through Grant Number DMR-1504226.

Microporous TiO2-WO3/TiO2 films with visible-light photocatalytic activity synthesized by micro arc oxidation and DC magnetron sputtering

International Nuclear Information System (INIS)

Wu, Kee-Rong; Hung, Chung-Hsuang; Yeh, Chung-Wei; Wu, Jiing-Kae

2012-01-01

Highlights: ► A simple MAO is used to prepare porous WO 3 /TiO 2 layer on Ti sheet as a visible-light enabled catalyst. ► The photocatalytic activity of the WO 3 /TiO 2 is enhanced by sputtering over an N,C-TiO 2 layer. ► This is ascribed to the synergetic effect of hybrid sample prepared by two-step method. - Abstract: This study reports the preparation of microporous TiO 2 -WO 3 /TiO 2 films with a high surface area using a two-step approach. A porous WO 3 /TiO 2 template was synthesized by oxidizing a titanium sheet using a micro arc oxidation (MAO) process. This sheet was subsequently overlaid with a visible light (Vis)-enabled TiO 2 (N,C-TiO 2 ) film, which was deposited by codoping nitrogen (N) and carbon (C) ions into a TiO 2 lattice using direct current magnetron sputtering. The resulting microporous TiO 2 -WO 3 /TiO 2 film with a 0.38-μm-thick N,C-TiO 2 top-layer exhibited high photocatalytic activity in methylene blue (MB) degradation among samples under ultraviolet (UV) and Vis irradiation. This is attributable to the synergetic effect of two-step preparation method, which provides a highly porous microstructure and the well-crystallized N,C-TiO 2 top-layer. This is because a higher surface area with high crystallinity favors the adsorption of more MB molecules and more photocatalytic active areas. Thus, the microporous TiO 2 -WO 3 /TiO 2 film has promising applications in the photocatalytic degradation of dye solution under UV and Vis irradiation. These results imply that the microporous WO 3 /TiO 2 can be used as a template of hybrid electrode because it enables rapid fabrication.

Synthesis and structural characterization of (H4APPIP)[V3(C2O4)2(HPO4)3(PO4)(H2O)]·6H2O (APPIP=1,4-bis(3-aminopropyl)piperazine), a layered vanadium oxalatophosphate containing double 6-ring units

International Nuclear Information System (INIS)

Tang, M.-F.; Lii, K.-H.

2004-01-01

A new vanadium(III) oxalatophosphate has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction and thermogravimetric analysis. It crystallizes in the triclinic space group P1-bar with a=11.604(2) A, b=12.391(2) A, c=15.220(3) A, α=71.090(3) deg., β=82.630(3) deg., γ=62.979(3) deg., V=1843.8(5) A 3 and Z=2. The structure consists of V 6 (HPO 4 ) 6 double 6-ring (D6R) units connected by coordinating C 2 O 4 2- and PO 4 3- anions to form anionic sheets in the ab plane with charge-compensating quadruply protonated 1,4-bis(3-aminopropyl)piperazinium cations and water molecules between the sheets. It is one of the few compounds with 2D layer structures and the second example containing D6R units in the system of metal oxalatophosphates. The iron analogue was also synthesized

Design Of A Bi-Functional α-Fe2O3/Zn2SiO4:Mn2+ By Layer-By-Layer Assembly Method

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Yu Ri

2015-06-01

Full Text Available This work describes the design of bi-functional α-Fe2O3/Zn2SiO4:Mn2+ using a two-step coating process. We propose a combination of pigments (α-Fe2O3 and phosphor (Zn2SiO4:Mn2+ glaze which is assembled using a layer-by-layer method. A silica-coated α-Fe2O3 pigment was obtained by a sol-gel method and a Zn2+ precursor was then added to the silica-coated α-Fe2O3 to create a ZnO layer. Finally, the Zn2SiO4:Mn2+ layer was prepared with the addition of Mn2+ ions to serve as a phosphor precursor in the multi-coated α-Fe2O3, followed by annealing at a temperature above 1000°C. Details of the phase structure, color and optical properties of the multi-functional α-Fe2O3/Zn2SiO4:Mn2+ were characterized by transmission electron microscopy and X-ray diffraction analyses.

Low temperature synthesis of layered NaxCoO2 and KxCoO2 from ...

Indian Academy of Sciences (India)

Unknown

Layered oxides have interesting chemical and physical properties. .... composition of these crystalline phases were obtained from scanning electron microscopy ... 2.2a Cobalt estimation: About 50 mg of the compound was dissolved in 10 ml of 6 M ... images of the parent Na0⋅2CoO2 and those ion exchanged with H+, Li+ ...

Structural and electronic properties of the transition layer at the SiO2/4H-SiC interface

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Wenbo Li

2015-01-01

Full Text Available Using first-principles methods, we generate an amorphous SiO2/4H-SiC interface with a transition layer. Based this interface model, we investigate the structural and electronic properties of the interfacial transition layer. The calculated Si 2p core-level shifts for this interface are comparable to the experimental data, indicating that various SiCxOy species should be present in this interface transition layer. The analysis of the electronic structures reveals that the tetrahedral SiCxOy structures cannot introduce any of the defect states at the interface. Interestingly, our transition layer also includes a C-C=C trimer and SiO5 configurations, which lead to the generation of interface states. The accurate positions of Kohn-Sham energy levels associated with these defects are further calculated within the hybrid functional scheme. The Kohn-Sham energy levels of the carbon trimer and SiO5 configurations are located near the conduction and valence band of bulk 4H-SiC, respectively. The result indicates that the carbon trimer occurred in the transition layer may be a possible origin of near interface traps. These findings provide novel insight into the structural and electronic properties of the realistic SiO2/SiC interface.

Copper(II) perrhenate Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2}: Synthesis from isopropanol and CuReO{sub 4}, structure and properties

Energy Technology Data Exchange (ETDEWEB)

Mikhailova, D., E-mail: d.mikhailova@ifw-dresden.de [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, D-76434 Eggenstein-Leopoldshafen (Germany); Institute for Complex Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany); Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden (Germany); Engel, J.M. [Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, D-64287 Darmstadt (Germany); Schmidt, M. [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, D-01187 Dresden (Germany); Tsirlin, A.A. [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Ehrenberg, H. [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials (IAM), Hermann-von-Helmholtz-Platz 1, D-76434 Eggenstein-Leopoldshafen (Germany); Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 2, D-64287 Darmstadt (Germany)

2015-12-15

The crystal structure of Cu{sup +}Re{sup 7+}O{sub 4} is capable of a quasi-reversible incorporation of C{sub 3}H{sub 7}OH molecules. A room-temperature reaction between CuReO{sub 4} and C{sub 3}H{sub 7}OH under oxidizing conditions leads to the formation of a novel metal-organic hybrid compound Cu{sup 2+}(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2}. Upon heating under reducing conditions, this compound transforms back into CuReO{sub 4}, albeit with ReO{sub 2} and metallic Cu as by-products. The crystal structure of Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} solved from single-crystal X-ray diffraction (Pbca, a=10.005(3) Å, b=7.833(2) Å, and c=19.180(5) Å) reveals layers of corner-sharing CuO{sub 6}-octahedra and ReO{sub 4}-tetrahedra, whereas isopropyl groups are attached to both sides of these layers, thus providing additional connections within the layers through hydrogen bonds. Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} is paramagnetic down to 4 K because the spatial arrangement of the Cu{sup 2+} half-filled orbitals prevents magnetic superexchange. The paramagnetic effective moment of 2.0(1) μ{sub B} is slightly above the spin-only value and typical for Cu{sup 2+} ions. - Highlights: • Novel Cu(C{sub 3}H{sub 7}OH){sub 2}(ReO{sub 4}){sub 2} compound has a sequence of inorganic and organic layers. • Hydrogen bonds provide an additional bonding Isopropanol molecules serve as a reducing agent during decomposition. • No direct Cu-O-Re-O-Cu connections via d{sub x2-y2} orbital of Cu{sup 2+} explain paramagnetism. • Hydrogen bonds provide an additional bonding. • Isopropanol molecules serve as a reducing agent during decomposition.

Electronic configuration of the c(2 x 2)MnCu two-dimensional alloy in layered structures supported on Cu(100)

International Nuclear Information System (INIS)

Gallego, S; Munoz, M C; Huttel, Y; Avila, J; Asensio, M C

2003-01-01

The c(2 x 2)MnCu surface alloy on Cu(100) can be considered as a purely two-dimensional magnetic system where the Mn atoms exhibit a large corrugation closely related to their high spin moment. In this paper we investigate the influence of the atomic environment on the electronic and magnetic properties of the two-dimensional alloyed layer, extending our study to the less known multilayered system made of MnCu two-dimensional alloy layers embedded in a Cu crystal. The analysis is based on angle-resolved photoelectron spectroscopy measurements and calculations using the Green function matching method, which allows us to treat exactly the projection of the three-dimensional lattice on the c(2 x 2) plane. A complete study of the valence band is performed along the two-dimensional Brillouin zone in a wide energy range. We show that the presence of Mn results in an important redistribution of the spin-polarized electronic states of the neighbouring Cu atoms. This redistribution is not accompanied by a net charge transfer between different atoms, and also the spin moment of Cu remains small. Most of the new features induced by Mn in the surface alloy are also present in the multilayered system, evidencing that they are specific to the two-dimensional alloyed layer and not surface effects

Inorganic-organic hybrid structure: Synthesis, structure and magnetic properties of a cobalt phosphite-oxalate, [C4N2H12][Co4(HPO3)2(C2O4)3

International Nuclear Information System (INIS)

Mandal, Sukhendu; Natarajan, Srinivasan

2005-01-01

A hydrothermal reaction of a mixture of cobalt (II) oxalate, phosphorous acid, piperazine and water at 150 o C for 96h followed by heating at 180 o C for 24h gave rise to a new inorganic-organic hybrid solid, [C 4 N 2 H 12 ][Co 4 (HPO 3 ) 2 (C 2 O 4 ) 3 ], I. The structure consists of edge-shared CoO 6 octahedra forming a [Co 2 O 10 ] dimers that are connected by HPO 3 and C 2 O 4 units forming a three-dimensional structure with one-dimensional channels. The amine molecules are positioned within these channels. The oxalate units have a dual role of connecting within the plane of the layer as well as out of the plane. Magnetic susceptibility measurement shows the compound orders antiferromagnetically at low temperature (T N =22K). Crystal data: I, monoclinic, space group=P2 1 /c (No. 14). a=7.614(15), b=7.514(14), c=17.750(3)A, β=97.351(3) o , V=1007.30(3)A 3 , Z=2, ρ calc =2.466g/cm 3 , μ (MoKα) =3.496mm -1 , R 1 =0.0310 and wR 2 =0.0807 data [I>2σ(I)

Electronic structure of magnesium diboride and related compounds

International Nuclear Information System (INIS)

Paduani, C.

2003-01-01

The electronic structure of AlB 2 -type diborides and related compounds has been investigated in first-principles calculations with the molecular cluster discrete variational method. For MgB 2 was studied the effect of the lattice relaxation on the total density of states at the Fermi energy (N(ε F )). The results indicated that a contraction of about 2% in the lattice spacings a and c can lead to a slight increase of N(ε F ) for boron. In the MB 2 diborides, M=Al, Ti, V, Cr, Zr, Nb, Mo and Ta, the largest contributions to N(ε F ) is observed for Cr, Mo and Nb. TiB 2 possess the highest chemical stability in the series. The electronic specific heat coefficient γ also is calculated for the diborides. The method is employed to obtain the partial B2p contribution to the total DOS at the Fermi level with the introduction of a monolayer of solute atoms as a substitution for Mg atoms of Na, Al, Ca, Ti, V, Cr, Zr, Nb, Mo and Ta in layered superstructures.. /M/B 2 /Mg/B 2 /.. A stronger covalent bonding between boron atoms is identified in these cases. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Identification and bioactivity of compounds from the fungus Penicillium sp. CYE-87 isolated from a marine tunicate.

Science.gov (United States)

Shaala, Lamiaa A; Youssef, Diaa T A

2015-03-25

In the course of our continuous interest in identifying bioactive compounds from marine microbes, we have investigated a tunicate-derived fungus, Penicillium sp. CYE-87. A new compound with the 1,4-diazepane skeleton, terretrione D (2), together with the known compounds, methyl-2-([2-(1H-indol-3-yl)ethyl]carbamoyl)acetate (1), tryptamine (3), indole-3-carbaldehyde (4), 3,6-diisobutylpyrazin-2(1H)-one (5) and terretrione C (6), were isolated from Penicillium sp. CYE-87. The structures of the isolated compounds were established by spectral analysis, including 1D (1H, 13C) and 2D (COSY, multiplicity edited-HSQC and HMBC) NMR and HRESIMS, as well as comparison of their NMR data with those in the literature. The compounds were evaluated for their antimigratory activity against the human breast cancer cell line (MDA-MB-231) and their antiproliferation activity against HeLa cells. Compounds 2 and 6 showed significant antimigratory activity against MDA-MB-231, as well as antifungal activity against C. albicans.

Development and application of graphite-SiO2/Al2O3/Nb2O5-methylene blue (GRP-SiAlNb-MB composite for electrochemical determination of dopamine

Directory of Open Access Journals (Sweden)

Juliana de Fátima Giarola

2017-03-01

Full Text Available In the present paper an amperometric sensor based on graphite-SiO2/Al2O3/Nb2O5-methylene blue (GRP-SiAlNb-MB composite has been successfully prepared for dopamine (DA determination in real samples. The electrochemical behavior of DA at the GRP-SiAlNb-MB has been evaluated by employing cyclic voltammetry. The best ratio (m/m of GRP-SiAlNb-MB composite was found to be 1:0.54. Under optimized conditions (pH 7.5 in 0.15 mol L−1 phosphate buffer the amperometry method responds linearly to DA from 5.0 up to 500.0 μmol L−1 (r = 0.995 with limits of detection and quantification of 1.49 and 4.97 μmol L−1, respectively. The developed method was successfully applied for DA determination in real samples of pharmaceutical formulations and can be used for routine quality control analysis of pharmaceutical formulations containing DA. The use of inorganic matrix SiAlNb was found to be very useful to adsorb MB in the composite material with further improvement of the anodic peak current of DA.

Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

OpenAIRE

Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

2015-01-01

A new BiS2-based superconductor Bi2(O,F)S2 was discovered. This is a layered compound consisting of alternate stacking structure of rock-salt-type BiS2 superconducting layer and fluorite-type Bi(O,F) blocking layer. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2, which is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis length increased and decreased, respe...

Improved interface and electrical properties of atomic layer deposited Al2O3/4H-SiC

Science.gov (United States)

Suvanam, Sethu Saveda; Usman, Muhammed; Martin, David; Yazdi, Milad. G.; Linnarsson, Margareta; Tempez, Agnès; Götelid, Mats; Hallén, Anders

2018-03-01

In this paper we demonstrate a process optimization of atomic layer deposited Al2O3 on 4H-SiC resulting in an improved interface and electrical properties. For this purpose the samples have been treated with two pre deposition surface cleaning processes, namely CP1 and CP2. The former is a typical surface cleaning procedure used in SiC processing while the latter have an additional weak RCA1 cleaning step. In addition to the cleaning and deposition, the effects of post dielectric annealing (PDA) at various temperatures in N2O ambient have been investigated. Analyses by scanning electron microscopy show the presence of structural defects on the Al2O3 surface after annealing at 500 and 800 °C. These defects disappear after annealing at 1100 °C, possibly due to densification of the Al2O3 film. Interface analyses have been performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight medium energy ion scattering (ToF MEIS). Both these measurements show the formation of an interfacial SiOx (0 < x < 2) layer for both the CP1 and CP2, displaying an increased thickness for higher temperatures. Furthermore, the quality of the sub-oxide interfacial layer was found to depend on the pre deposition cleaning. In conclusion, an improved interface with better electrical properties is shown for the CP2 sample annealed at 1100 °C, resulting in lower oxide charges, strongly reduced flatband voltage and leakage current, as well as higher breakdown voltage.

[KDy(Hptc3(H3ptc]n·2n(Hbipy·5n(H2O, a Layered Coordination Polymer Containing DyO6N3 Tri-Capped Trigonal Prisms (H3ptc = Pyridine 2,4,6-Tricarboxylic Acid, C8H5NO6; Bipy = 2,2'-Bipyridine, C10H8N2

Directory of Open Access Journals (Sweden)

Shoaib Anwar

2012-08-01

Full Text Available The synthesis, structure and properties of the bimetallic layered coordination polymer, [KDy(C8H3NO63(C8H5NO6]n·2n(C10H9N2·5n(H2O = [KDy(Hptc3(H3ptc]n·2n(Hbipy·5n(H2O, are described. The Dy3+ ion is coordinated by three O,N,O-tridentate doubly-deprotonated pyridine tri-carboxylate (Hptc ligands to generate a fairly regular DyO6N3 tri-capped trigonal prism, with the N atoms acting as the caps. The potassium ion is coordinated by an O,N,O-tridentate H3ptc molecule as well as monodentate and bidentate Hptc ligands to result in an irregular KNO9 coordination geometry. The ligands bridge the metal-atom nodes into a bimetallic, layered, coordination polymer, which extends as corrugated layers in the (010 plane, with the mono-protonated bipyridine cations and water molecules occupying the inter-layer regions: Unlike related structures, there are no dysprosium–water bonds. Many O–HLO and N–HLO hydrogen bonds consolidate the structure. Characterization and bioactivity data are described. Crystal data: C52H42DyKN8O29, Mr = 1444.54, triclinic,  (No. 2, Z = 2, a = 9.188(2 Å, b = 15.7332(17 Å, c = 19.1664(19 Å, α = 92.797(6°, β = 92.319(7°, γ = 91.273(9°, V = 2764.3(7 Å3, R(F = 0.029, wR(F2 = 0.084.

Gold-Catalyzed Formal C-C Bond Insertion Reaction of 2-Aryl-2-diazoesters with 1,3-Diketones.

Science.gov (United States)

Ren, Yuan-Yuan; Chen, Mo; Li, Ke; Zhu, Shou-Fei

2018-06-29

The transition-metal-catalyzed formal C-C bond insertion reaction of diazo compounds with monocarbonyl compounds is well established, but the related reaction of 1,3-diketones instead gives C-H bond insertion products. Herein, we report a protocol for a gold-catalyzed formal C-C bond insertion reaction of 2-aryl-2-diazoesters with 1,3-diketones, which provides efficient access to polycarbonyl compounds with an all-carbon quaternary center. The aryl ester moiety plays a crucial role in the unusual chemoselectivity, and the addition of a Brønsted acid to the reaction mixture improves the yield of the C-C bond insertion product. A reaction mechanism involving cyclopropanation of a gold carbenoid with an enolate and ring-opening of the resulting donor-acceptor-type cyclopropane intermediate is proposed. This mechanism differs from that of the traditional Lewis-acid-catalyzed C-C bond insertion reaction of diazo compounds with monocarbonyl compounds, which involves a rearrangement of a zwitterion intermediate as a key step. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

X-ray structure study of boron chelates with N-(pyridyl-2)- and N-(thiazolyl-2)urea derivatives

International Nuclear Information System (INIS)

Teslya, I.A.; Starikova, Z.A.; Boldyreva, O.G.; AN SSSR, Moscow. Inst. Organicheskoj Khimii)

1987-01-01

Spectral (IR, Raman) and X-ray structural investigations of CdBr 2 xMB (MB-2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo(3.3.0)-octadione-3.7 m, mebicar) (λMo, 634 reflections, R=0.045) are performed. Rhombic crystals: a=3.9921(7), b=10.6938(25), c=14.9947(62)A,L=2, sp. gr. F nmm . The structure is polymerically laminated. Mebicar molecules play the role of bidentate-bridge ligands. O atoms of both carbonyl groups bind Cd atoms of the neighbouring complexes in chains directed along y axis. In the direction of x axis such chains are connected by bridge Br atoms in layers parallel to (xy0) plane. the coordination polyhedron of Cd atoms is a distorted octahedron. Bond lengths Cd-Br 2.738, Cd-O 2.37 A Bond lengths Cd-Br 2.738, Cd-O 2.37 A

trans-(2-Benzoylpyridine-κ2N,Odichlorido[2-(2-pyridylcarbonylphenyl-κ2C1,N]iridium(III dichloromethane solvate

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available The title compound, [Ir(C12H8NOCl2(C12H9NO]·CH2Cl2, which was obtained from the reaction of iridium(III chloride trihydrate and 2-benzoylpyridine, contains an IrIII atom coordinated by two N, one O, one C and two Cl atoms in trans positions, forming a distorted octahedral environment. The solvent molecule CH2Cl2 is disordered over two positions with an occupancy of 0.8:0.2.

Crystal structure of fac-[2-(4-methyl-5-phenylpyridin-2-ylphenyl-κ2C1,N]bis[2-(pyridin-2-ylphenyl-κ2C1,N]iridium(III

Directory of Open Access Journals (Sweden)

Chi-Heon Lee

2016-12-01

Full Text Available In the title compound, [Ir(C11H8N2(C18H14N], the IrIII ion adopts a distorted octahedral coordination environment defined by three C,N-chelating ligands, one stemming from a 2-(4-phenyl-5-methylpyridin-2-ylphenyl ligand and two from 2-(pyridin-2-ylphenyl ligands, arranged in a facial manner. The IrIII ion lies almost in the equatorial plane [deviation = 0.0069 (15 Å]. In the crystal, intermolecular π–π stacking interactions, as well as intermolecular C—H...π interactions, are present, leading to a three-dimensional network.

Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders

Energy Technology Data Exchange (ETDEWEB)

Diao, Yunhua, E-mail: 990722012@qq.com; Zhang, Kemin, E-mail: zhangkm@sues.edu.cn

2015-10-15

Highlights: • A TiC/TiB{sub 2} composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders. • A maximum hardness of 1100 HV was achieved in the laser clad TiC/TiB{sub 2} composite layer. • Corrosion resistance of the TC2 alloy in NaCl (3.5 wt%) aqueous solution can be improved after laser cladding. - Abstract: In the present work, a TiC/TiB{sub 2} composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB{sub 2}. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB{sub 2} intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens’ corrosion property is clearly becoming better than that of the substrate.

Compounds Containing Tetragonal Cu2+ Complexes: Is the dx2–y2–d3z2–r2 Gap a Direct Reflection of the Distortion?

DEFF Research Database (Denmark)

García-Fernández, Pablo; Barriuso, María Teresa; García Lastra, Juan Maria

2013-01-01

– complex. This internal field, especially important for layered compounds, is shown to explain all puzzling experimental facts on the d–d transitions of the studied systems and is of interest in the search of new Cu2+ and Ag2+ superconducting materials where a strong correlation between Δ...... to be not correct through the study of pure K2CuF4-, KCuF3-, and Cu2+-doped KZnF3 and K2ZnF4 model compounds. Indeed, ab initio calculations prove that Δ in these insulating materials also depends on the internal electric field created by the rest of lattice ions on active electrons confined in a given CuF64...

Impact of hydrogen absorption on crystal structure and magnetic properties of RE{sub 2}T{sub 2}X compounds

Energy Technology Data Exchange (ETDEWEB)

Mašková, S., E-mail: maskova@mag.mff.cuni.cz [Department of Condensed Matter Physics, Charles University, Prague 2 (Czech Republic); Kolomiets, A. [Department of Condensed Matter Physics, Charles University, Prague 2 (Czech Republic); Department of Physics, Lviv Polytechnic National University, Lviv (Ukraine); Havela, L. [Department of Condensed Matter Physics, Charles University, Prague 2 (Czech Republic); Andreev, A.V. [Institute of Physics, AVCR, Prague 8 (Czech Republic); Svoboda, P. [Department of Condensed Matter Physics, Charles University, Prague 2 (Czech Republic)

2015-10-05

Highlights: • RE{sub 2}Pd{sub 2}In(Sn) compounds absorb, depending on RE, different amounts of hydrogen. • Compounds with the light rare earths become amorphous upon the hydrogenation. • Compounds with the heavy rare earths preserve the original tetragonal structure. • Magnetic ordering temperatures of RE{sub 2}Pd{sub 2}In compounds are reduced by the hydrogenation. - Abstract: RE{sub 2}Pd{sub 2}In, RE{sub 2}Pd{sub 2}Sn compounds (RE = rare earth) absorb, depending on the rare earth (RE) element, different amounts of hydrogen. The parent compounds RE{sub 2}Pd{sub 2}In show the linear decrease of both lattice parameters and the unit cell volume with the increasing atomic number of RE, attributed to the lanthanide contraction. All the compounds absorb at least 2 H/f.u.; the tetragonal structure is merely expanded. The expansion is anisotropic (Δc/c > Δa/a), and for RE = Tb, Dy, Ho, and Er the lattice even contracts along the a-axis (Δa/a < 0), whereas Δc/c still weakly increases. A higher H concentration can be achieved in the compounds with light rare earths (La, Nd, both for In and Sn), which then become amorphous. The magnetic ordering temperatures of all studied RE{sub 2}Pd{sub 2}In compounds are dramatically reduced by the hydrogenation, typically to the temperature range below 1.8 K.

Positron lifetimes and distributions in the infinite-layer compound SrCuO2 and related materials

International Nuclear Information System (INIS)

Ishibashi, Shoji; Terada, Norio; Hirabayashi, Masayuki; Ihara, Hideo

1994-01-01

We have calculated distributions and lifetimes of positrons in the infinite-layer compound SrCuO 2 and those trapped at possible point defects therein. In the delocalized state, positrons show their density maxima at interstitial sites in the Sr planes and have a significant overlap also with Cu and O atoms. The corresponding positron lifetime is 149 ps. It has been revealed that the Sr vacancy strongly localizes positrons with the binding energy of 2.8 eV and the lifetime of 238 ps, while the O vacancy does not trap positrons. Calculations are also performed on related materials Sr 2 Cu 4 O 6 and Sr 4 Cu 6 O 10 , which are characterized by one-dimensional networks of edge-sharing CuO 4 squares. Positrons are predominantly distributed between these networks in these materials and their corresponding lifetimes are 170-171 ps. (orig.)

Synthesis and magnetic structure of the layered manganese oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Blandy, Jack N. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Boskovic, Jelena C. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Clarke, Simon J., E-mail: simon.clarke@chem.ox.ac.uk [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom)

2017-01-15

The synthesis of a high-purity sample of the layered oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} is reported. At ambient temperature it crystallises in the space group I4/mmm with two formula units in the unit cell and lattice parameters a=4.08771(1) Å, c=19.13087(8) Å. The compound displays mixed-valent manganese in a formal oxidation state close to +2.5 and powder neutron diffraction measurements reveal that below the Néel temperature of 63(1) K this results in an antiferromagnetic structure which may be described as A-type, modelled in the magnetic space group P{sub I}4/mnc (128.410 in the Belov, Neronova and Smirnova (BNS) scheme) in which localised Mn moments of 3.99(2) μ{sub B} are arranged in ferromagnetic layers which are coupled antiferromagnetically. In contrast to the isostructural compound Sr{sub 2}MnO{sub 2}Cu{sub 1.5}S{sub 2}, Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} does not display long range ordering of coinage metal ions and vacancies, nor may significant amounts of the coinage metal readily be deintercalated using soft chemical methods. - Graphical abstract: Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} containing mixed valent Mn ions undergoes magnetic ordering with ferromagnetic coupling within MnO{sub 2} sheets and antiferromagnetic coupling between MnO{sub 2} sheets. - Highlights: • High purity sample of Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} obtained. • Magnetic structure determined. • Compared with related mixed-valent manganite oxide chalcogenides.

Ruthenium(II) carbonyl compounds with the 4'-chloro-2,2':6',2''-terpyridine ligand.

Science.gov (United States)

Tatikonda, Rajendhraprasad; Haukka, Matti

2017-04-01

Two ruthenium carbonyl complexes with the 4'-chloro-2,2':6',2''-terpyridine ligand (tpy-Cl, C 15 H 10 ClN 3 ), i.e. [RuCl(tpy-Cl)(CO) 2 ][RuCl 3 (CO) 3 ] (I) [systematic name: cis -di-carbonyl-chlorido(4'-chloro-2,2':6',2''-terpyridine-κ 3 N )ruthenium(II) fac -tricarbonyltri-chlorido-ruthenate(II)], and [RuCl 2 (tpy-Cl)(CO) 2 ] (II) [ cis -dicarbonyl- trans -di-chlorido(4'-chloro-2,2':6',2''-terpyridine-κ 2 N 1 , N 1' )ruthenium(II)], were synthesized and characterized by single-crystal X-ray diffraction. The Ru II atoms in both centrosymmetric structures (I) and (II) display similar, slightly distorted octa-hedral coordination spheres. The coordination sphere in the complex cation in compound (I) is defined by three N atoms of the tridentate tpy-Cl ligand, two carbonyl carbon atoms and one chlorido ligand; the charge is balanced by an octa-hedral [Ru(CO) 3 Cl 3 ] - counter-anion. In the neutral compound (II), the tpy-Cl ligand coordinates to the metal only through two of its N atoms. The coordination sphere of the Ru II atom is completed by two carbonyl and two chlorido ligands. In the crystal structures of both (I) and (II), weak C-H⋯Cl inter-actions are observed.

Synthesis of [5,6-13C2, 1-14C]olivetolic acid, methyl [1'-13C]olivetolate and [5,6-13C2, 1-14C]cannabigerolic acid

International Nuclear Information System (INIS)

Porwoll, J.P.; Leete, E.

1985-01-01

Potential advanced intermediates in the biosynthesis of delta 9 -tetrahydrocannabinol, the major psychoactive principle of marijuana, have been synthesized labeled with two contiguous 13 C atoms and 14 C. Methyl [5,6- 13 C 2 , 1- 14 C]olivetolate was prepared from lithium [ 13 C 2 ]acetylide and dimethyl [2- 14 C]malonate. Reaction with geranyl bromide afforded methyl [5,6- 13 C 2 , 1- 14 C]cannabigerolate, and hydrolysis of these methyl esters with lithium propyl mercaptide yielded the corresponding labeled acids. The 13 C- 13 C couplings observable in the 13 C NMR spectra of these 13 C-enriched compounds and their synthetic precursors are recorded. Methyl [1'- 14 C]olivetolate was prepared from 13 CO 2 to confirm assignments of the 13 C chemical shifts in the pentyl side chain of these compounds. (author)

Topotactic synthesis of a new BiS2-based superconductor Bi2(O,F)S2

Science.gov (United States)

Okada, Tomoyuki; Ogino, Hiraku; Shimoyama, Jun-ichi; Kishio, Kohji

2015-02-01

A new BiS2-based superconductor, Bi2(O,F)S2, was discovered. It is a layered compound consisting of alternately stacked structure of rock-salt-type BiS2 superconducting layers and fluorite-type Bi(O,F) blocking layers. Bi2(O,F)S2 was obtained as the main phase by topotactic fluorination of undoped Bi2OS2 using XeF2. This is the first topotactic synthesis of an electron-doped superconductor via reductive fluorination. With increasing F-content, a- and c-axis lengths increased and decreased, respectively, and Tc increased to 5.1 K.

Preparation of Ferroelectric Thin Films of Bismuth Layer Structured Compounds

Science.gov (United States)

Watanabe, Hitoshi; Mihara, Takashi; Yoshimori, Hiroyuki; Araujo, Carlos

1995-09-01

Ferroelectric thin films of bismuth layer structured compounds, SrBi2Ta2O9, SrBi2Nb2O9, SrBi4Ti4O15 and their solid solutions, were formed onto a sputtered platinum layer on a silicon substrate using spin-on technique and metal-organic decomposition (MOD) method. X-ray diffraction (XRD) analysis and some electrical measurements were performed on the prepared thin films. XRD results of SrBi2(Ta1- x, Nb x)2O9 films (0≤x≤1) showed that niobium ions substitute for tantalum ions in an arbitrary ratio without any change of the layer structure and lattice constants. Furthermore, XRD results of SrBi2 xTa2O9 films (0≤x≤1.5) indicated that the formation of the bismuth layer structure does not always require an accurate bismuth content. The layer structure was formed above 50% of the stoichiometric bismuth content in the general formula. SrBi2(Ta1- x, Nb x)2O9 films with various Ta/Nb ratios have large enough remanent polarization for nonvolatile memory application and have shown high fatigue resistance against 1011 cycles of full switching of the remanent polarization. Mixture films of the three compounds were also investigated.

Bis(tetramethylcyclopentadienyl)titanium chemistry. Molecular structures of [(C(5)HMe(4))(mu-eta(1) : eta(5)-C(5)Me(4))Ti](2) and [(C(5)HMe(4))(2)Ti]N-2(2)

NARCIS (Netherlands)

deWolf, JM; Blaauw, R; Meetsma, A; Teuben, JH; Gyepes, R; Varga, [No Value; Mach, K; Veldman, N; Spek, AL

1996-01-01

Thermolysis of bis(tetramethylcyclopentadienyl)-stabilized titanium(III) compounds (C(5)HMe(4))(2)TiR (R = Me (2), Ph (3)) yields, in marked contrast with the bis(pentamethylcyclopentadienyl) analog, the dimeric product [(C(5)HMe(4))(mu-eta(1):eta(5)-C(5)Me(4))Ti](2) (4), With a bridging metalated

Antiphase Boundaries in the Turbostratically Disordered Misfit Compound (BiSe)(1+δ)NbSe2.

Science.gov (United States)

Mitchson, Gavin; Falmbigl, Matthias; Ditto, Jeffrey; Johnson, David C

2015-11-02

(BiSe)(1+δ)NbSe2 ferecrystals were synthesized in order to determine whether structural modulation in BiSe layers, characterized by periodic antiphase boundaries and Bi-Bi bonding, occurs. Specular X-ray diffraction revealed the formation of the desired compound with a c-axis lattice parameter of 1.21 nm from precursors with a range of initial compositions and initial periodicities. In-plane X-ray diffraction scans could be indexed as hk0 reflections of the constituents, with a rectangular basal BiSe lattice and a trigonal basal NbSe2 lattice. Electron micrographs showed extensive turbostratic disorder in the samples and the presence of periodic antiphase boundaries (approximately 1.5 nm periodicity) in BiSe layers oriented with the [110] direction parallel to the zone axis of the microscope. This indicates that the structural modulation in the BiSe layers is not due to coherency strain resulting from commensurate in-plane lattices. Electrical transport measurements indicate that holes are the dominant charge carrying species, that there is a weak decrease in resistivity as temperature decreases, and that minimal charge transfer occurs from the BiSe to NbSe2 layers. This is consistent with the lack of charge transfer from the BiX to the TX2 layers reported in misfit layer compounds where antiphase boundaries were observed. This suggests that electronic considerations, i.e., localization of electrons in the Bi-Bi pairs at the antiphase boundaries, play a dominant role in stabilizing the structural modulation.

The cation-deficient Ruddlesden-Popper oxysulfide Y2Ti2O5S2 as a layered sulfide: topotactic potassium intercalation to form KY2Ti2O5S2.

Science.gov (United States)

Rutt, Oliver J; Hill, Timothy L; Gál, Zoltán A; Hayward, Michael A; Clarke, Simon J

2003-12-01

Potassium intercalation into the cation-deficient n = 2 Ruddlesden-Popper oxysulfide Y(2)Ti(2)O(5)S(2) to form KY(2)Ti(2)O(5)S(2) has been carried out by reaction of the oxysulfide with potassium vapor in sealed metal tubes at 400 degrees C, potassium naphthalide in THF at 50 degrees C, or potassium in liquid ammonia at temperatures as low as -78 degrees C. Insertion of potassium is topotactic, and although a site 12-coordinate by oxide ions is vacant in the perovskite-type oxide slabs of the structure, potassium is too large to enter this site via the 4-coordinate window, and instead enters the rock-salt-type sulfide layers of the structure which necessitates a 30% increase in the lattice parameter c normal to the layers. In contrast with one of the sodium intercalates of Y(2)Ti(2)O(5)S(2) (beta-NaY(2)Ti(2)O(5)S(2)) in which sodium occupies a tetrahedral site in the sulfide layers, potassium favors an 8-coordinate site which necessitates a relative translation of adjacent oxide slabs. KY(2)Ti(2)O(5)S(2) is tetragonal: P4/mmm, a = 3.71563(4) A, c = 14.8682(2) A (at 298 K), Z = 1. Although the resistivity (3.4(1) x 10(3) Omega cm) is larger than would be expected for a metal, temperature independent paramagnetism dominates the magnetic susceptibility, and the material is electronically very similar to the analogous sodium intercalate beta-NaY(2)Ti(2)O(5)S(2) which features reduced-titanium-containing oxide layers of very similar geometry and electron count.

X-Ray Diffraction and μ-Raman Investigation of the Monoclinic-Orthorhombic Phase Transition in Th1-xUx(C2O4)2. 2H2O Solid Solutions

International Nuclear Information System (INIS)

Clavier, N.; Dacheux, N.; Clavier, N.; Hingant, N.; Dacheux, N.; Barre, N.; Rivenet, M.; Obbade, S.; Abraham, F.

2010-01-01

A complete Th 1-x U x (C 2 O 4 ) 2 . 2H 2 O solid solution was prepared by mild hydrothermal synthesis from a mixture of hydrochloric solutions containing cations and oxalic acid. The crystal structure has been solved from twinned single crystals for x=0, 0. 5, and 1 with monoclinic symmetry, space group C2/c, leading to unit cell parameters of a ≅ to 10. 5 Angstroms, b ≅ 8. 5 Angstrom, and c ≅ 9. 6 Angstrom. The crystal structure consists of a two-dimensional arrangement of actinide centers connected through bis-bidentate oxalate ions forming squares. The actinide metal is coordinated by eight oxygen atoms from four oxalate entities and two water oxygen atoms forming a bi-capped square anti-prism. The connection between the layers is assumed by hydrogen bonds between the water molecules and the oxygen of oxalate of an adjacent layer. Under these conditions, the unit cell contains two independent oxalate ions. From high-temperature μ-Raman and X-ray diffraction studies, the compounds were found to undergo a transition to an orthorhombic form (space group Ccca). The major differences in the structural arrangement concern the symmetry of uranium, which decreases from C2 to D2, leading to a unique oxalate group. Consequently, the ν s (C-O) double band observed in the Raman spectra recorded at room temperature turned into a singlet. This transformation was then used to make the phase transition temperature more precise as a function of the uranium content of the sample. (authors)

Effect of TiN-ZrO{sub 2} intermediate layer on the microstructure and magnetic properties of FePt and FePt-SiO{sub 2}-C thin films

Energy Technology Data Exchange (ETDEWEB)

Dong, K.F., E-mail: dongkf1981@163.com; Mo, W.Q.; Jin, F.; Song, J.L.

2017-06-15

Highlights: • The TiN-ZrO{sub 2} consisted of solid solution of Ti(Zr)ON segregated by amorphous ZrO{sub 2}. • With doping ZrO{sub 2} into TiN layer, grain size of FePt films significantly decreased. • By introducing TiN-ZrO{sub 2}/TiN combined layer, the magnetic properties were improved. - Abstract: The microstructures and magnetic properties of FePt based thin films grown on TiN-ZrO{sub 2} and TiN-ZrO{sub 2}/TiN intermediate layers were systematically investigated. The TiN-ZrO{sub 2} intermediate layer was granular consisting of grains of solid solution of Ti(Zr)ON segregated by amorphous ZrO{sub 2}. It was found with doping ZrO{sub 2} into TiN intermediate layer, grain size of FePt-SiO{sub 2}-C films significantly decreased. Simultaneously, the isolation was obviously improved and grain size distribution became more uniform. However, the magnetic properties of the FePt-SiO{sub 2}-C films grown on TiN-ZrO{sub 2} intermediate layers were slowly deteriorated, which was due to the disturbance of the epitaxial growth of FePt by amorphous ZrO{sub 2} in TiN-ZrO{sub 2} intermediate layer. In order to improve the TiN-ZrO{sub 2} (0 0 2) texture and the crystallinity of TiN-ZrO{sub 2}, TiN-ZrO{sub 2}/TiN combined intermediate layer was introduced. And the magnetic properties were improved, simultaneously, achieving the benefit of grain size reduction. For the FePt 4 nm-SiO{sub 2} 40 vol%-C 20 vol% film grown on TiN/TiN-ZrO{sub 2} 30 vol% combined intermediate layer, well isolated FePt (0 0 1) granular films with coercivity higher than 17.6 kOe and an average size as small as 6.5 nm were achieved.

2-(2-Pyridylpyridinium (2,2′-bipyridine-κ2N,N′tetrakis(nitrato-κ2O,O′bismuthate(III

Directory of Open Access Journals (Sweden)

Shu-Shen Zhang

2011-10-01

Full Text Available The structure of the title compound, (C10H9N2[Bi(NO34(C10H8N2], consists of 2-(2-pyridylpyridinium cations and anions [Bi(NO34(C10H8N2]−. The Bi3+ ion lies on the twofold axis. It is coordinated by two nitrogen atoms from one 2,2′-bipyridine ligand and eight oxygen atoms from four NO3− anions. The disordered cation is positioned at the inversion centre. The [Bi(NO34(C10H8N2]− anions and 2-(2-pyridylpyridinium cations are connected via N—H...O hydrogen bonds into chains. Moreover, these chains are further linked into a two-dimensional layered structure through π–π stacking interactions between bipyridine ligands along the c axis [centroid–centroid distance = 2.868 (4 Å].

Vortex pinning in artificially layered Ba(Fe,Co)2As2 film

Science.gov (United States)

Oh, M. J.; Lee, Jongmin; Seo, Sehun; Yoon, Sejun; Seo, M. S.; Park, S. Y.; Kim, Ho-Sup; Ha, Dong-Woo; Lee, Sanghan; Jo, Youn Jung

2018-06-01

Static high critical current densities (Jc) > 1 MA/cm2 with magnetic field parallel or perpendicular to c-axis were realized in Co-doped/undoped multilayerd BaFe2As2 films. We made a current bridge by FIB to allow precise measurements, and confirmed that the boundary quality using FIB was considerably better than the quality achieved using a laser. The presence of a high in-plane Jc suggested the existence of c-axis correlated vortex pinning centers. To clarify the relationship between the Jc performance and superstructures, we investigated the magnetic flux pinning mechanism using scaling theory of the volume pinning force Fp(H). The Jc(H) curves, Fp/Fp,max vs. h = H/Hirr curves, and parameters p and q depended on the characteristics of the flux pinning mechanism. It was found that the dominant pinning mechanism of Co-doped/undoped multilayerd BaFe2As2 films was Δl-pinning and the inserted undoped BaFe2As2 layers remained non-superconducting. The dominant pin geometry varied when the magnetic field direction changed. It was concluded that the artificially layered BaFe2As2 film is a 3-D superconductor due to its long correlation length compared to the thickness of the non-superconducting layer.

Evaluation of 89 compounds for identification of substrates for cynomolgus monkey CYP2C76, a new bupropion/nifedipine oxidase.

Science.gov (United States)

Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Shimizu, Makiko; Uehara, Shotaro; Fujino, Hideki; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

2015-01-01

Cynomolgus monkeys are widely used in preclinical studies during drug development because of their evolutionary closeness to humans, including their cytochrome P450s (P450s). Most cynomolgus monkey P450s are almost identical (≥90%) to human P450s; however, CYP2C76 has low sequence identity (approximately 80%) to any human CYP2Cs. Although CYP2C76 has no ortholog in humans and is partly responsible for species differences in drug metabolism between cynomolgus monkeys and humans, a broad evaluation of potential substrates for CYP2C76 has not yet been conducted. In this study, a screening of 89 marketed compounds, including human CYP2C and non-CYP2C substrates or inhibitors, was conducted to find potential CYP2C76 substrates. Among the compounds screened, 19 chemicals were identified as substrates for CYP2C76, including substrates for human CYP1A2 (7-ethoxyresorufin), CYP2B6 (bupropion), CYP2D6 (dextromethorphan), and CYP3A4/5 (dextromethorphan and nifedipine), and inhibitors for CYP2B6 (sertraline, clopidogrel, and ticlopidine), CYP2C8 (quercetin), CYP2C19 (ticlopidine and nootkatone), and CYP3A4/5 (troleandomycin). CYP2C76 metabolized a wide variety of the compounds with diverse structures. Among them, bupropion and nifedipine showed high selectivity to CYP2C76. As for nifedipine, CYP2C76 formed methylhydroxylated nifedipine, which was not produced by monkey CYP2C9, CYP2C19, or CYP3A4, as identified by mass spectrometry and estimated by a molecular docking simulation. This unique oxidative metabolite formation of nifedipine could be one of the selective marker reactions of CYP2C76 among the major CYP2Cs and CYP3As tested. These results suggest that monkey CYP2C76 contributes to bupropion hydroxylation and formation of different nifedipine oxidative metabolites as a result of its relatively large substrate cavity. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Diffusion Monte Carlo studies of MB-pol (H{sub 2}O){sub 2−6} and (D{sub 2}O){sub 2−6} clusters: Structures and binding energies

Energy Technology Data Exchange (ETDEWEB)

Mallory, Joel D.; Mandelshtam, Vladimir A. [Department of Chemistry, University of California, Irvine, California 92697 (United States)

2016-08-14

We employ the diffusion Monte Carlo (DMC) method in conjunction with the recently developed, ab initio-based MB-pol potential energy surface to characterize the ground states of small (H{sub 2}O){sub 2−6} clusters and their deuterated isotopomers. Observables, other than the ground state energies, are computed using the descendant weighting approach. Among those are various spatial correlation functions and relative isomer fractions. Interestingly, the ground states of all clusters considered in this study, except for the dimer, are delocalized over at least two conformations that differ by the orientation of one or more water monomers with the relative isomer populations being sensitive to the isotope substitution. Most remarkably, the ground state of the (H{sub 2}O){sub 6} hexamer is represented by four distinct cage structures, while that of (D{sub 2}O){sub 6} is dominated by the prism, i.e., the global minimum geometry, with a very small contribution from a prism-book geometry. In addition, for (H{sub 2}O){sub 6} and (D{sub 2}O){sub 6}, we performed DMC calculations to compute the ground states constrained to the cage and prism geometries. These calculations compared results for three different potentials, MB-pol, TTM3/F, and q-TIP4P/F.

Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

International Nuclear Information System (INIS)

Pachmayr, Ursula Elisabeth

2017-01-01

This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe_1_-_xS_x was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li_0_._8Fe_0_._2)OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li_0_._8Fe_0_._2)OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe_4 tetrahedra were found via this synthesis method. The iron selenides A_2Fe_4Se_6 (A = K, Rb, Cs) consist of double chains of [Fe_2Se_3]"1"-, whereas a new compound Na_6(H_2O)_1_8Fe_4Se_8 exhibits [Fe_4Se_8]"6"- 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard to iron-chalcogenide based superconductors this synthesis strategy is encouraging. It seems probable

Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

Energy Technology Data Exchange (ETDEWEB)

Pachmayr, Ursula Elisabeth

2017-04-06

This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe{sub 1-x}S{sub x} was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li{sub 0.8}Fe{sub 0.2})OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li{sub 0.8}Fe{sub 0.2})OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe{sub 4} tetrahedra were found via this synthesis method. The iron selenides A{sub 2}Fe{sub 4}Se{sub 6} (A = K, Rb, Cs) consist of double chains of [Fe{sub 2}Se{sub 3}]{sup 1-}, whereas a new compound Na{sub 6}(H{sub 2}O){sub 18}Fe{sub 4}Se{sub 8} exhibits [Fe{sub 4}Se{sub 8}]{sup 6-} 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard

Plasma-assisted atomic layer deposition of Al(2)O(3) and parylene C bi-layer encapsulation for chronic implantable electronics.

Science.gov (United States)

Xie, Xianzong; Rieth, Loren; Merugu, Srinivas; Tathireddy, Prashant; Solzbacher, Florian

2012-08-27

Encapsulation of biomedical implants with complex three dimensional geometries is one of the greatest challenges achieving long-term functionality and stability. This report presents an encapsulation scheme that combines Al(2)O(3) by atomic layer deposition with parylene C for implantable electronic systems. The Al(2)O(3)-parylene C bi-layer was used to encapsulate interdigitated electrodes, which were tested invitro by soak testing in phosphate buffered saline solution at body temperature (37 °C) and elevated temperatures (57 °C and 67 °C) for accelerated lifetime testing up to 5 months. Leakage current and electrochemical impedance spectroscopy were measured for evaluating the integrity and insulation performance of the coating. Leakage current was stably about 15 pA at 5 V dc, and impedance was constantly about 3.5 MΩ at 1 kHz by using electrochemical impedance spectroscopy for samples under 67 °C about 5 months (approximately equivalent to 40 months at 37 °C). Alumina and parylene coating lasted at least 3 times longer than parylene coated samples tested at 80 °C. The excellent insulation performance of the encapsulation shows its potential usefulness for chronic implants.

Magnetic anisotropy of YNi2B2C single crystals

International Nuclear Information System (INIS)

Baran, M.; Gladczuk, L.; Gorecka, J.; Szymczak, H.; Szymczak, R.; Drzazga, Z.; Winiarska, H.

1994-01-01

Reversible and irreversible magnetization processes in YNi 2 B 2 C single crystal have been measured and analysed in terms of existing theories. Performed measurements suggest that anisotropy of the effective mass in YNi 2 B 2 C superconductor is rather small and similar to that observed in conventional superconductors. Effect of hydrostatic pressure on T c is shown to be typical of low-temperature superconductors. It is suggested that the layered structure of YNi 2 B 2 C has some effect on the irreversible magnetization processes observed in this superconductor. ((orig.))

Design and syntheses of hybrid metal–organic materials based on K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] metallotectons

Energy Technology Data Exchange (ETDEWEB)

Sun, Yayong; Zong, Yingxia; Ma, Haoran; Zhang, Ao; Liu, Kang; Wang, Debao, E-mail: dbwang@qust.edu.cn; Wang, Wenqiang; Wang, Lei, E-mail: inorchemwl@126.com

2016-05-15

By using K{sub 3}[M(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O [M(III)=Fe, Al, Cr] (C{sub 2}O{sub 4}{sup 2−}=oxalate) metallotectons as the starting material, we have synthesized eight novel complexes with formulas [{Fe(C_2O_4)_2(H_2O)_2}{sub 2}]·(H–L{sub 1}){sub 2}·H{sub 2}O 1, [Fe(C{sub 2}O{sub 4})Cl{sub 2}]·(H{sub 2}–L{sub 2}){sub 0.5}·(L{sub 2}){sub 0.5}·H{sub 2}O 2, [{Fe(C_2O_4)_1_._5Cl_2}{sub 2}]·(H–L{sub 3}){sub 4}3, [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]·(H{sub 2}–L{sub 4}){sub 2}·2H{sub 2}O 4, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H{sub 2}–L{sub 5})·2H{sub 2}O 5, K[Al(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 6, K[Cr(C{sub 2}O{sub 4}){sub 3}]·2H{sub 2}O 7, Na[Fe(C{sub 2}O{sub 4}){sub 3}]·(H–L{sub 6}){sub 2}·2H{sub 2}O 8 (with L{sub 1}=4-dimethylaminopyridine, L{sub 2}=2,3,5,6-tetramethylpyrazine, L{sub 3}=2-aminobenzimidazole, L{sub 4}=1,4-bis-(1H-imidazol-1-yl)benzene, L{sub 5}=1,4-bis((2-methylimidazol-1-yl)methyl)benzene, L{sub 6}=2-methylbenzimidazole). Their structures have been determined by single-crystal X-ray diffraction analyses, elemental analyses, IR spectra and thermogravimetric analyses. Compound 3 is a 2D H-bonded supramolecular architecture. Others are 3D supramolecular structures. Compound 1 shows a [Fe(C{sub 2}O{sub 4}){sub 2}(H{sub 2}O){sub 2}]{sup −} unit and 3D antionic H-bonded framework. Compound 2 features a [Fe(C{sub 2}O{sub 4})Cl{sub 2}]{sup -} anion and 1D iron-oxalate-iron chain. Compound 3 features a [Fe{sub 2}(C{sub 2}O{sub 4}){sub 3}Cl{sub 4}]{sup 4−} unit. Compound 4 features distinct [Fe{sub 2}(C{sub 2}O{sub 4})Cl{sub 8}]{sup 4−} units, which are mutual linked by water molecules to generated a 2D H-bonded network. Compound 5 features infinite ladder-like chains constructed by [Al(C{sub 2}O{sub 4}){sub 3}]{sup 3−} units and K{sup +} cations. The 1D chains are further extended into 3D antionic H-bonded framework through O–H···O H-bonds. Compounds 6–8 show 2D [KAl(C{sub 2}O

Single step hydrothermal based synthesis of M(II)Sb2O6 (M = Cd ...

Indian Academy of Sciences (India)

characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive .... SEM images and EDAX analysis of (a) and (b) CdSb2O6 and (c) and (d) ZnSb2O6. ... The parent compound, ilmenite (NaSbO3) could degrade MB.

Insight into π-hole interactions containing the inorganic heterocyclic compounds S2N2/SN2P2.

Science.gov (United States)

Lu, Bo; Zhang, Xueying; Meng, Lingpeng; Zeng, Yanli

2017-08-01

Similar to σ-hole interactions, the π-hole interaction has attracted much attention in recent years. According to the positive electrostatic potentials above and below the surface of inorganic heterocyclic compounds S 2 N 2 and three SN 2 P 2 isomers (heterocyclic compounds 1-4), and the negative electrostatic potential outside the X atom of XH 3 (X = N, P, As), S 2 N 2 /SN 2 P 2 ⋯XH 3 (X = N, P, As) complexes were constructed and optimized at the MP2/aug-cc-pVTZ level. The X atom of XH 3 (X = N, P, As) is almost perpendicular to the ring of the heterocyclic compounds. The π-hole interaction energy becomes greater as the trend goes from 1⋯XH 3 to 4⋯XH 3 . These π-hole interactions are weak and belong to "closed-shell" noncovalent interactions. According to the energy decomposition analysis, of the three attractive terms, the dispersion energy contributes more than the electrostatic energy. The polarization effect also plays an important role in the formation of π-hole complexes, with the contrasting phenomena of decreasing electronic density in the π-hole region and increasing electric density outside the X atom of XH 3 (X = N, P, As). Graphical abstract Computed density difference plots for the complexes 3⋯NH 3 (a 1 ), 3⋯PH 3 (b 1 ), 3⋯AsH 3 (c 1 ) and electron density shifts for the complexes 3⋯NH 3 (a 2 ), 3⋯PH 3 (b 2 ),3⋯AsH 3 (c 2 ) on the 0.001 a.u. contour.

Stability, Reactivity, and Constituent Interaction in TiSe2-Based Metastable Misfit Layer Compounds Synthesized from Designed Amorphous Precursors

Science.gov (United States)

Merrill, Devin R.

A series of intergrowth compounds with the basic formula [(MSe) 1+delta]m(TiSe2)n are reported. The compounds are prepared from modulated elemental reactants and display interesting structural and electronic behavior. Section 1 of this dissertation outlines initial attempts to characterize constituent interaction. The first member of the SnSe based subclass is reported and displays the highest Seebeck coefficient of any m = n = 1 compound reported to date, and a surprising amount of order is observed, compared to previously reported compounds. With properly established deposition parameters, the synthesis was extended to included the m = 2-4 compounds. These compounds display interesting electronic behavior that suggests the band structure shifts considerably as the SnSe block is expanded, affecting the interaction between the constituent layers. The first compound based on BiSe is then reported, suggesting that the Bi structure donates more conduction electrons to the band structure. Targeted substitution through kinetic control is the focus of Section 2, and a family of (PbxSn1-xSe)1+deltaTiSe 2 is reported over the entire range of x, even though a miscibility gap exists in the bulk PbxSn1-xSe system. The resulting alloyed intergrowth compounds also display equal or higher mobility than the end members, suggesting modulation doping could be used to affect transport properties. As a proof of principle, the analogous system based on a Bi xSn1-xSe constituent was prepared to attempt to systematically affect carrier concentration. It was found that while carrier concentration can be controlled, the evolving structure affects the doping efficiency of the Bi atoms and mobility in the structure. Section 3 outlines attempts to form higher order TiSe2-based heterostructures and the important chemical considerations observed during the preparation of these materials. The 3 component systems in the Pb-Sn-Ti-Se system can be formed at low temperature, with SnSe2 rather than

Bulk Kosterlitz-Thouless Type Molecular Superconductor β″-(BEDT-TTF)2[(H2O)(NH4)2Cr(C2O4)3]·18-crown-6.

Science.gov (United States)

Martin, Lee; Lopez, Jordan R; Akutsu, Hiroki; Nakazawa, Yasuhiro; Imajo, Shusaku

2017-11-20

A new molecular superconductor, β″-(BEDT-TTF) 2 [(H 2 O)(NH 4 ) 2 Cr(C 2 O 4 ) 3 ]·18-crown-6, has been synthesized from the organic donor molecule BEDT-TTF with the anion Cr(C 2 O 4 ) 3 3- . The crystal structure consists of conducting organic layers of BEDT-TTF molecules which adopt the β″ packing motif (layer A), layers of NH 4 + and Λ-Cr(C 2 O 4 ) 3 3- (layer B), layers of (H 2 O)(NH 4 )18-crown-6 (layer C), and layers of NH 4 + and Δ-Cr(C 2 O 4 ) 3 3- (layer D) which produce a superstructure with a repeating pattern of ABCDABCDA. As a result of this packing arrangement, this is the 2D superconductor with the widest gap between conducting layers where only a single donor packing motif is present (β″). Superconducting critical temperatures at ambient pressure observed by electrical transport and magnetic measurements are 4.0-4.9 and 2.5 K, respectively. The strong 2D nature of this system, the broad transition to T zero at 1.8K, and the transition of α of V ∝ I α from 1 to 3 on I-V curves strongly suggest that the superconducting transition is very close to a Kosterlitz-Thouless transition. The magnetic field dependence of the superconducting critical temperature parallel to the conducting plane gives an upper critical field μ 0 H c2∥ > 8 T, which is over the calculated Pauli-Clogston limit for this material.

X-Ray diffraction and mu-Raman investigation of the monoclinic-orthorhombic phase transition in Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solutions.

Science.gov (United States)

Clavier, Nicolas; Hingant, Nina; Rivenet, Murielle; Obbade, Saïd; Dacheux, Nicolas; Barré, Nicole; Abraham, Francis

2010-02-15

A complete Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solution was prepared by mild hydrothermal synthesis from a mixture of hydrochloric solutions containing cations and oxalic acid. The crystal structure has been solved from twinned single crystals for x = 0, 0.5, and 1 with monoclinic symmetry, space group C2/c, leading to unit cell parameters of a approximately 10.5 A, b approximately 8.5 A, and c approximately 9.6 A. The crystal structure consists of a two-dimensional arrangement of actinide centers connected through bis-bidentate oxalate ions forming squares. The actinide metal is coordinated by eight oxygen atoms from four oxalate entities and two water oxygen atoms forming a bicapped square antiprism. The connection between the layers is assumed by hydrogen bonds between the water molecules and the oxygen of oxalate of an adjacent layer. Under these conditions, the unit cell contains two independent oxalate ions. From high-temperature mu-Raman and X-ray diffraction studies, the compounds were found to undergo a transition to an orthorhombic form (space group Ccca). The major differences in the structural arrangement concern the symmetry of uranium, which decreases from C2 to D2, leading to a unique oxalate group. Consequently, the nu(s)(C-O) double band observed in the Raman spectra recorded at room temperature turned into a singlet. This transformation was then used to make the phase transition temperature more precise as a function of the uranium content of the sample.

Poly[(μ3-benzene-1,3,5-tricarboxylato-κ3O1:O3:O5(μ2-2-methylimidazolato-κ2N:N′tris(2-methylimidazole-κNdizinc(II

Directory of Open Access Journals (Sweden)

Palanikumar Maniam

2011-06-01

Full Text Available Hydrothermal reaction involving zinc nitrate hexahydrate, trisodium benzene-1,3,5-tricarboxylate (Na3BTC and 2-methylimidazole (2-MeImH yielded the title compound, [Zn2(C9H3O6(C4H5N2(C4H6N23]. In this mixed-ligand metal-organic compound, Zn2+ ions are coordinated by N atoms from 2-MeImH molecules and (2-MeIm− ions, as well as by O atoms from (BTC3− ions. This results in two different distorted tetrahedra, viz. ZnN3O and ZnN2O2. These tetrahedra are interconnected via (BTC3− ions and N:N′-bridging (2-MeIm− ions, thus forming a layered structure in the bc plane. Hydrogen bonds between the O atoms of carboxylate ions and NH groups of 2-MeImH ligands link the layers into a three-dimensional structure.

Temperature stability of c-axis oriented LiNbO3/SiO2/Si thin film layered structures

International Nuclear Information System (INIS)

Tomar, Monika; Gupta, Vinay; Mansingh, Abhai; Sreenivas, K.

2001-01-01

Theoretical calculations have been performed for the temperature stability of the c-axis oriented LiNbO 3 thin film layered structures on passivated silicon (SiO 2 /Si) substrate with and without a non-piezoelectric SiO 2 overlayer. The phase velocity, electromechanical coupling coefficient and temperature coefficient of delay (TCD) have been calculated. The thicknesses of various layers have been determined for optimum SAW performance with zero TCD. The presence of a non-piezoelectric SiO 2 overlayer on LiNbO 3 film is found to significantly enhance the coupling coefficient. The optimized results reveal that a high coupling coefficient of K 2 =3.45% and a zero TCD can be obtained in the SiO 2 /LiNbO 3 /SiO 2 /Si structure with a 0.235λ thick LiNbO 3 layer sandwiched between 0.1λ thick SiO 2 layers. (author)

Homoleptic Diphosphacyclobutadiene Complexes [M(η4-P2C2R2)2]x- (M=Fe, Co; x=0, 1)

NARCIS (Netherlands)

Wolf, Robert; Ehlers, A.W.; Khusniyarov, M.M.; Hartl, F.; de Bruin, B.; Long, G.J.; Grandjean, F.; Schappacher, F.M.; Pöttgen, R.; Slootweg, J.C.; Lutz, M.; Spek, A.L.; Lammertsma, K.

2011-01-01

The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)ACHTUNGTRENUNG(thf)2][Fe(η4- P2C2tBu2)2] (K1), [K([18]crown-6)- ACHTUNGTRENUNG(thf)2][Co(h4-P2C2tBu2)2] (K2), and

Homoleptic Diphosphacyclobutadiene Complexes [M(η(4)-P2C2R2)(2]x- (M = Fe, Co; x=0, 1)

NARCIS (Netherlands)

Wolf, R.; Ehlers, A.W.; Khusniyarov, M.M.; Hartl, F.; de Bruin, B.; Long, G.J.; Grandjean, F.; Schappacher, F.M.; Pöttgen, R.; Slootweg, J.C.; Lutz, M.; Spek, A.L.; Lammertsma, K.

2010-01-01

The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)(thf)(2)[Fe(η(4)-P(2)C(2)tBu(2))(2)] (K1), [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)tBu(2))(2)] (K2), and

A possibility of enhancing Jc in MgB2 film grown on metallic hastelloy tape with the use of SiC buffer layer

International Nuclear Information System (INIS)

Putri, W. B. K.; Kang, B.; Ranot, M.; Lee, J. H.; Kang, W. N.

2014-01-01

We have grown MgB 2 on SiC buffer layer by using metallic Hastelloy tape as the substrate. Hastelloy tape was chosen for its potential practical applications, mainly in the power cable industry. SiC buffer layers were deposited on Hastelloy tapes at 400, 500, and 600 degrees C by using a pulsed laser deposition method, and then by using a hybrid physical-chemical vapor deposition technique, MgB 2 films were grown on the three different SiC buffer layers. An enhancement of critical current density values were noticed in the MgB 2 films on SiC/Hastelloy deposited at 500 and 600 degrees C. From the surface analysis, smaller and denser grains of MgB 2 tapes are likely to cause this enhancement. This result infers that the addition of SiC buffer layers may contribute to the improvement of superconducting properties of MgB 2 tapes.

Human Sulfatase 2 inhibits in vivo tumor growth of MDA-MB-231 human breast cancer xenografts

International Nuclear Information System (INIS)

Peterson, Sarah M; Concino, Michael F; Liaw, Lucy; Martini, Paolo GV; Iskenderian, Andrea; Cook, Lynette; Romashko, Alla; Tobin, Kristen; Jones, Michael; Norton, Angela; Gómez-Yafal, Alicia; Heartlein, Michael W

2010-01-01

Extracellular human sulfatases modulate growth factor signaling by alteration of the heparin/heparan sulfate proteoglycan (HSPG) 6-O-sulfation state. HSPGs bind to numerous growth factor ligands including fibroblast growth factors (FGF), epidermal growth factors (EGF), and vascular endothelial growth factors (VEGF), and are critically important in the context of cancer cell growth, invasion, and metastasis. We hypothesized that sulfatase activity in the tumor microenvironment would regulate tumor growth in vivo. We established a model of stable expression of sulfatases in the human breast cancer cell line MDA-MB-231 and purified recombinant human Sulfatase 2 (rhSulf2) for exogenous administration. In vitro studies were performed to measure effects on breast cancer cell invasion and proliferation, and groups were statistically compared using Student's t-test. The effects of hSulf2 on tumor progression were tested using in vivo xenografts with two methods. First, MDA-MB-231 cells stably expressing hSulf1, hSulf2, or both hSulf1/hSulf2 were grown as xenografts and the resulting tumor growth and vascularization was compared to controls. Secondly, wild type MDA-MB-231 xenografts were treated by short-term intratumoral injection with rhSulf2 or vehicle during tumor growth. Ultrasound analysis was also used to complement caliper measurement to monitor tumor growth. In vivo studies were statistically analyzed using Student's t test. In vitro, stable expression of hSulf2 or administration of rhSulf2 in breast cancer cells decreased cell proliferation and invasion, corresponding to an inhibition of ERK activation. Stable expression of the sulfatases in xenografts significantly suppressed tumor growth, with complete regression of tumors expressing both hSulf1 and hSulf2 and significantly smaller tumor volumes in groups expressing hSulf1 or hSulf2 compared to control xenografts. Despite significant suppression of tumor volume, sulfatases did not affect vascular

Monoclinic MB phase and phase instability in [110] field cooled Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 single crystals

Science.gov (United States)

Yao, Jianjun; Cao, Hu; Ge, Wenwei; Li, Jiefang; Viehland, D.

2009-08-01

We report the finding of a monoclinic MB phase in Pb(Zn1/3Nb2/3)O3-4.5%PbTiO3 single crystals. High precision x-ray diffraction investigations of [110] field cooled crystals have shown a transformation sequence of cubic(C)→tetragonal(T)→orthorhombic(O)→monoclinic(MB), which is different from that previously reported [A.-E. Renault et al., J. Appl. Phys. 97, 044105 (2005)]. Beginning in the zero-field-cooled condition at 383 K, a rhombohedral (R)→MB→O sequence was observed with increasing field. Coexisting MB and O phases were then found upon removal of field, which fully transformed to MB on cooling to room temperature.

Draft Genome Sequence of the Antagonistic Rhizosphere Bacterium Serratia plymuthica Strain PRI-2C

NARCIS (Netherlands)

Garbeva, P.; van Elsas, J.D.; de Boer, W.

Serratia plymuthica strain PRI-2C is a rhizosphere bacterial strain with antagonistic activity against different plant pathogens. Here we present the 5.39-Mb (G+C content, 55.67%) draft genome sequence of S. plymuthica strain PRI-2C with the aim of providing insight into the genomic basis of its

A new nonlinear optical silicate carbonate K2Ca[Si2O5](CO3) with a hybrid structure of kalsilite and soda-like layered fragments

Science.gov (United States)

Belokoneva, Elena L.; Stefanovich, Sergey Yu.; Volkov, Anatoly S.; Dimitrova, Olga V.

2016-10-01

Single crystals of a new silicate carbonate, K2Ca[Si2O5](CO3), have been synthesized in a multi-components hydrothermal solution with a pH value close to neutral and a high concentration of a carbonate mineralizer. The new compound has an axial structure (s.g. P6322) with unit cell parameters a = 5.04789 (15), c = 17.8668 (6) Å. Pseudosymmetry of the structure corresponds to s.g. P63/mmc which is broken only by one oxygen position. The structure consists of two layered fragments: one of the type of the mineral kalsilite (KAlSiO4) and the other of the high-temperature soda-like α-Na2CO3, Ca substituting for Na. The electro-neutral layer K2[Si2O5] (denoted K) as well as the layer Ca(CO3) (denoted S) may separately correspond to individual structures. In K2Ca[Si2O5](CO3) the S-K layers are connected together via Ca-O interactions between Ca atoms from the carbonate layer and apical O atoms from the silicate one, and also via K-O interlayer interactions. A hypothetical acentric structure, sp.gr. P-62c, is predicted on the basis of the order-disorder theory. It presents another symmetrical option for the arrangement of K-layers relative to S-layers. The K,Ca-silicate-carbonate powder produces a moderate SHG signal that is two times larger that of the α-quartz powder standard and close to other silicates with acentric structures and low electronic polarizability.

Role of field-effect on c-Si surface passivation by ultrathin (2-20 nm) atomic layer deposited Al2O3

NARCIS (Netherlands)

Terlinden, N.M.; Dingemans, G.; Sanden, van de M.C.M.; Kessels, W.M.M.

2010-01-01

Al2O3 synthesized by plasma-assisted atomic layer deposition yields excellent surface passivation of crystalline silicon (c-Si) for films down to ~ 5 nm in thickness. Optical second-harmonic generation was employed to distinguish between the influence of field-effect passivation and chemical

Photocatalytic Degradation of 4-Nitrophenol by C, N-TiO2: Degradation Efficiency vs. Embryonic Toxicity of the Resulting Compounds

Science.gov (United States)

Osin, Oluwatomiwa A.; Yu, Tianyu; Cai, Xiaoming; Jiang, Yue; Peng, Guotao; Cheng, Xiaomei; Li, Ruibin; Qin, Yao; Lin, Sijie

2018-06-01

The photocatalytic activity of TiO2 based photocatalysts can be improved by structural modification and elemental doping. In this study, through rational design, one type of carbon and nitrogen co-doped TiO2 (C, N-TiO2) photocatalyst with mesoporous structure was synthesized with improved photocatalytic activity in degrading 4-nitrophenol under simulated sunlight irradiation. The photocatalytic degradation efficiency of the C, N-TiO2 was much higher than the anatase TiO2 (A-TiO2) based on absorbance and HPLC analyses. Moreover, using zebrafish embryos, we showed that the intermediate degradation compounds generated by photocatalytic degradation of 4-nitrophenol had higher toxicity than the parent compound. A repeated degradation process was necessary to render complete degradation and non-toxicity to the zebrafish embryos. Our results demonstrated the importance of evaluating the photocatalytic degradation efficiency in conjunction with the toxicity assessment of the degradation compounds.

Anchoring a uniform TiO{sub 2} layer on graphene oxide sheets as an efficient visible light photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Cong, Ye, E-mail: congye626@126.com [Hubei Province Key Laboratory of Coal Conversion and New Carbon Materials, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Long, Mei; Cui, Zhengwei [Hubei Province Key Laboratory of Coal Conversion and New Carbon Materials, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Xuanke [Hubei Province Key Laboratory of Coal Conversion and New Carbon Materials, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Hubei Province Key Laboratory of High Temperature Ceramic and Refractory, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Dong, Zhijun; Yuan, Guanming; Zhang, Jiang [Hubei Province Key Laboratory of Coal Conversion and New Carbon Materials, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

2013-10-01

TiO{sub 2}–graphene oxide (GO) was successfully prepared by a two-step approach including the in situ growth of a uniform TiC layer on graphene oxide sheets and subsequently oxidation conversion of TiC to anatase TiO{sub 2}. The as-prepared composites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The photocatalytic activity was evaluated by degradation of methylene blue (MB) under visible light irradiation. The results suggest that TiO{sub 2}–GO keep the similar morphology with the pristine GO sheets and the nanosize anatase TiO{sub 2} particles distribute uniformly and densely on the surface of GO sheets. TiO{sub 2} particles contact closely with GO via Ti-O-C bonds. The presence of GO provides a good support substrate and enhances the adsorption capacity and photo-degradation ability of the composite photocatalyst. And by adjusting the molar ratio of GO and titanium powder in the molten salt process, TiO{sub 2}–GO nanocomposites with controllable contents of GO and TiO{sub 2}, good adsorption capacity and excellent photo-degradation ability can be obtained.

Influence of face-centered-cubic texturing of Co2Fe6B2 pinned layer on tunneling magnetoresistance ratio decrease in Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd](n)-SyAF layer.

Science.gov (United States)

Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Chae, Kyo-Suk; Shim, Tae-Hun; Lian, Guoda; Kim, Moon; Park, Jea-Gun

2015-05-15

The TMR ratio of Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd]n-SyAF layer decreased rapidly when the ex situ magnetic annealing temperature (Tex) was increased from 275 to 325 °C, and this decrease was associated with degradation of the Co2Fe6B2 pinned layer rather than the Co2Fe6B2 free layer. At a Tex above 325 °C the amorphous Co2Fe6B2 pinned layer was transformed into a face-centered-cubic (fcc) crystalline layer textured from [Co/Pd]n-SyAF, abruptly reducing the Δ1 coherence tunneling of perpendicular-spin-torque electrons between the (100) MgO tunneling barrier and the fcc Co2Fe6B2 pinned layer.

A de novo 1.58 Mb deletion, including MAP2K6 and mapping 1.28 Mb upstream to SOX9, identified in a patient with Pierre Robin sequence and osteopenia with multiple fractures.

Science.gov (United States)

Smyk, Marta; Roeder, Elizabeth; Cheung, Sau Wai; Szafranski, Przemyslaw; Stankiewicz, Paweł

2015-08-01

Defects of long-range regulatory elements of dosage-sensitive genes represent an under-recognized mechanism underlying genetic diseases. Haploinsufficiency of SOX9, the gene essential for development of testes and differentiation of chondrocytes, results in campomelic dysplasia, a skeletal malformation syndrome often associated with sex reversal. Chromosomal rearrangements with breakpoints mapping up to 1.6 Mb up- and downstream to SOX9, and disrupting its distant cis-regulatory elements, have been described in patients with milder forms of campomelic dysplasia, Pierre Robin sequence, and sex reversal. We present an ∼1.58 Mb deletion mapping ∼1.28 Mb upstream to SOX9 that encompasses its putative long-range cis-regulatory element(s) and MAP2K6 in a patient with Pierre Robin sequence and osteopenia with multiple fractures. Low bone mass panel testing using massively parallel sequencing of 23 nuclear genes, including COL1A1 and COL1A2 was negative. Based on the previous mouse model of Map2k6, suggesting that Sox9 is likely a downstream target of the p38 MAPK pathway, and our previous chromosome conformation capture-on-chip (4C) data showing potential interactions between SOX9 promoter and MAP2K6, we hypothesize that deletion of MAP2K6 might have affected SOX9 expression and contributed to our patient's phenotype. © 2015 Wiley Periodicals, Inc.

PHOTOELECTRON-SPECTROSCOPY STUDY OF THE ELECTRONIC-STRUCTURE OF THE INCOMMENSURATE INTERGROWTH COMPOUNDS (SBS)(1.15)(TIS2)(N) WITH N=1, 2

NARCIS (Netherlands)

REN, Y; HAAS, C; WIEGERS, GA

1995-01-01

The electronic structure of the inorganic misfit-layer compounds (SbS)(1.15)(TiS2)(n) (n = 1,2) has been investigated using x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS) and x-ray absorption spectroscopy (XAS). These compounds are built of alternating modulated

Synthesis and crystal structure of Na6[(UO2)3O(OH)3(SeO4)2]2·10H2O

International Nuclear Information System (INIS)

Baeva, E.Eh.; Serezhkina, L.B.; Virovets, A.V.; Peresypkina, E.V.

2006-01-01

The complex Na 6 [(UO 2 ) 3 O(OH) 3 (SeO 4 ) 2 ] 2 ·10H 2 O (I) is synthesized and studied by monocrystal X-ray diffraction. The compound crystallizes in the orthorhombic crystal system with the unit cell parameters: a=14.2225(7) A, b=18.3601(7) A, c=16.5406(6) A, V=4319.2(3) A 3, Z=4, space group Cmcm, R 1 =0.0406. Compound I is found to be a representative of the crystal-chemical group A 3 M 3 M 3 2 T 2 3 (A=UO 2 2+ , M 3 =O 2- , M 2 =OH - , T 3 =SeO 4 2- ) of the uranyl complexes; it contains layer uranium-containing groups [(UO 2 ) 3 O(OH) 3 (SeO 4 ) 2 ] 3- . These layers are linked to form a three-dimensional cage through bonds formed by the sodium atoms with the oxygen atoms of the uranyl ions and SeO 4 groups that belong to different layers [ru

μ-Oxalato-κ4O1,O2:O1′,O2′-bis[aqua(2,2′-bipyridine-κN(nitrato-κ2O,O′lead(II

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Gang-Hong Pan

2012-10-01

Full Text Available The title compound, [Pb2(C2O4(NO32(C10H8N22(H2O2], was synthesized hydrothermally. The binuclear complex molecule is centrosymmetric, the inversion centre being located at the mid-point of the oxalate C—C bond. The PbII ion is heptacoordinated by the O atom of one water molecule, two oxalate O atoms, two nitrate O atoms and two 2,2′-bipyridine N atoms, forming an irregular coordination environemnt. Intermolecular O—H...O hydrogen bonds between water molecules and oxalate and nitrate ions result in the formation of layers parallel to (010. π–π interactions between pyridine rings in adjacent layers, with centroid–centroid distances of 3.584 (2 Å, stabilize the structural set-up.

Variation in the Optical Properties of the SiC-SiO2 Composite Antireflection Layer in Crystalline Silicon Solar Cells by Annealing

Science.gov (United States)

Jannat, Azmira; Li, Zhen Yu; Akhter, M. Shaheer; Yang, O.-Bong

2017-11-01

This study showed the effects of annealing on a sol-gel-derived SiC-SiO2 composite antireflection (AR) layer and investigated the optical and photovoltaic properties of crystalline silicon (Si) solar cells. The SiC-SiO2 composite AR coating showed a considerable decrease in reflectance from 7.18% to 3.23% at varying annealing temperatures of 450-800°C. The refractive indices of the SiC-SiO2 composite AR layer were tuned from 2.06 to 2.45 with the increase in annealing temperature. The analysis of the current density-voltage characteristics indicated that the energy conversion efficiencies of the fabricated Si solar cells gradually increased from 16.99% to 17.73% with increasing annealing temperatures of 450-800°C. The annealing of the SiC-SiO2 composite AR layer in Si solar cells was crucial to improving the optical, morphological, and photovoltaic properties.

EPR of CU+2:Mb single crystal

International Nuclear Information System (INIS)

Nascimento, O.R.; Ribeiro, S.C.; Bemski, G.

1976-01-01

Copper introduced into met-myoglobin crystals occupies various sites as indicated by EPR parameters. CU 2+ (A) is probably liganded to histidine A10, lysine A14 and asparagine GH4 (Banaszak, 1965) and shows super-hyperfine interaction with a single (imidazole) nitrogen. Cu 2+ (B) and Cu 2+ (C) correspond to other anisotropic sites described with lesser details. Cu 2+ (A) exhibits a transition to an isotropic form with a transition temperature of 40.5 0 C. This transition is indicative of a conformational change in myoglobin and could correspond to a motion of A helix away from the GH section. The transition temperature is 7 0 C higher than the previously reported (Atanasov, 1971) one for myoglobin in solution

Two new two-dimensional organically templated phosphite compounds: (C6H16N2)0.5[M(HPO3)F], M=Fe(II) and Co(II): Solvothermal synthesis, crystal structures, thermal, spectroscopic, and magnetic properties

International Nuclear Information System (INIS)

Fernandez-Armas, Sergio; Mesa, Jose L.; Pizarro, Jose L.; Chung, U-Chan; Arriortua, Maria I.; Rojo, Teofilo

2005-01-01

The organically templated (C 6 H 16 N 2 ) 0.5 [M(HPO 3 )F] [M(II)=Fe (1) and Co (2)] compounds have been synthesized by using mild hydrothermal conditions under autogeneous pressure. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds are isostructural and crystallize in the C2/c monoclinic space group. The unit-cell parameters are a=5.607(1), b=21.276(4), c=11.652(1)A, β=93.74(1) deg. for the iron phase and a=5.5822(7), b=21.325(3), c=11.4910(1)A, β=93.464(9) o for the cobalt compound with Z=4. The crystal structure of these compounds consists of [M(HPO 3 )F] - anionic sheets. The layers are constructed from chains which contain [M 2 O 6 F 3 ] dimeric units linked by fluoride ions. The trans-1,4-diaminocyclohexane cations are placed in the interlayer space. The IR and Raman spectra show the bands corresponding to the phosphite oxoanion and organic dication. The Dq and Racah (B and C) parameters have been calculated from the diffuse reflectance spectra in the visible region. Dq parameter is 790cm -1 for compound (1). For phase (2) the Dq value is 725cm -1 and B and C are 930 and 4100cm -1 , respectively. The thermal evolution of the molar magnetic susceptibilities of these compounds show maxima at 20.0 and 6.0K for the iron(II) and cobalt(II) phases, respectively. These results indicate the existence of antiferromagnetic interactions in both compounds

Poly[diaqua(μ-4,4′-bipyridine-κ2N:N′[μ-2,2′-(p-phenylenedioxydiacetato-κ2O:O′]cadmium

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Guang-Yin Wang

2011-09-01

Full Text Available In the title compound, [Cd(C10H8O6(C10H8N2(H2O2]n, the CdII ion has inversion symmetry and is coordinated by O atoms from two water molecules and two bridging 2,2′-(μ-p-phenylenedioxydiacetate ligands and two N atoms from two 4,4′-bipyridine ligands, giving a slightly distorted octahedral geometry. The diacetate and 4,4′-bipyridine ligands also lie across inversion centers. The bridging ligands form layers parallel to (11overline{1}, with adjacent layers interconnected via O—H...O hydrogen bonds between the coordinated water molecules and the carboxylate O atoms, giving a three-dimensional supramolecular architecture.

A common behaviour of thermoelectric layered cobaltites: incommensurate spin density wave states in [Ca2Co4/3Cu2/3O4]0.62[CoO2] and [Ca2CoO3]0.62[CoO2

International Nuclear Information System (INIS)

Sugiyama, J; Brewer, J H; Ansaldo, E J; Itahara, H; Dohmae, K; Xia, C; Seno, Y; Hitti, B; Tani, T

2003-01-01

Magnetism of a misfit layered cobaltite [Ca 2 Co 4/3 Cu 2/3 O 4 ] x RS [CoO 2 ] (x ∼ 0.62, RS denotes a rocksalt-type block) was investigated by a positive muon spin rotation and relaxation (μ + SR) experiment. A transition to an incommensurate (IC) spin density wave (SDW) state was found below 180 K (= T C on ); and a clear oscillation due to a static internal magnetic field was observed below 140 K(= T C ). Furthermore, an anisotropic behaviour of the zero-field μ + SR experiment indicated that the IC-SDW lies in the a-b plane, with oscillating moments directed along the c axis. These results were quite similar to those for the related compound [Ca 2 CoO 3 ] 0.62 RS [CoO 2 ], i.e., Ca 3 Co 4 O 9 . Since the IC-SDW field in [Ca 2 Co 4/3 Cu 2/3 O 4 ] 0.62 RS [CoO 2 ] was approximately the same as those in pure and doped [Ca 2 CoO 3 ] 0.62 RS [CoO 2 ], it was concluded that the IC-SDW exists in the [CoO 2 ] planes

Low-dimensional compounds containing cyanide groups. XXV. Synthesis, spectroscopic properties and crystal structures of two ionic iron(II) complexes with tricyanomethanide: tris(1,10-phenanthroline-κ(2)N,N')iron(II) bis(tricyanomethanide) and tris(2,2'-bipyridine-κ(2)N,N')iron(II) bis(tricyanomethanide) sesquihydrate.

Science.gov (United States)

Potočňák, Ivan; Váhovská, Lucia; Herich, Peter

2014-05-01

Two new diamagnetic coordination compounds, [Fe(phen)3][C(CN)3]2, (I), and [Fe(bpy)3][C(CN)3]2·1.5H2O, (II), have been synthesized and characterized by single-crystal X-ray diffraction analysis, and IR and UV-Vis spectroscopy (phen is 1,10-phenanthroline, C12H8N2, and bpy is 2,2'-bipyridine, C10H8N2). Both compounds are ionic with distorted octahedral [Fe(phen)3](2+) or [Fe(bpy)3](2+) complex cations, with average Fe-N distances of 1.977 (2) and 1.971 (3) Å, respectively, and two uncoordinated planar tricyanomethanide, or [C(CN)3](-), counter-anions balancing the positive charges of the cations. Solvent water molecules and tcm anions in (II) are linked via O-H...N hydrogen bonds into negatively charged layers and the interlayer space is filled by [Fe(bpy)3](2+) cations. The structures of (I) and (II) are stabilized by π-π interactions between the stacked aromatic rings of the phen ligands of two adjacent cations and by O-H...N hydrogen bonds, respectively, and also by π-π stacking interactions between phen and tcm units in (I).

Crystal structure of a Ce2Fe2Mg15 compound

International Nuclear Information System (INIS)

Opainich, I.M.; Pavlyuk, V.V.; Bodak, O.I.

1996-01-01

A structure of a new Ce2Fe2Mg15 ternary compound (P63/mmc sp.gr., a=1.0324(5) nm, c=1.02080(4) nm) was determined by powder methods on a DRON-4.07 automatic diffractometer. The structure of a Ce2Fe2Mg15 crystal is a new variant of the ordered Th2Ni17 type superstructure, in which cerium atoms occupy the thorium positions; magnesium atoms occupy the nickel position 6g, 12k, and 12j; and iron atoms occupy the 4f position

Comparative genomic mapping of the bovine Fragile Histidine Triad (FHIT tumour suppressor gene: characterization of a 2 Mb BAC contig covering the locus, complete annotation of the gene, analysis of cDNA and of physiological expression profiles

Directory of Open Access Journals (Sweden)

Boussaha Mekki

2006-05-01

Full Text Available Abstract Background The Fragile Histidine Triad gene (FHIT is an oncosuppressor implicated in many human cancers, including vesical tumors. FHIT is frequently hit by deletions caused by fragility at FRA3B, the most active of human common fragile sites, where FHIT lays. Vesical tumors affect also cattle, including animals grazing in the wild on bracken fern; compounds released by the fern are known to induce chromosome fragility and may trigger cancer with the interplay of latent Papilloma virus. Results The bovine FHIT was characterized by assembling a contig of 78 BACs. Sequence tags were designed on human exons and introns and used directly to select bovine BACs, or compared with sequence data in the bovine genome database or in the trace archive of the bovine genome sequencing project, and adapted before use. FHIT is split in ten exons like in man, with exons 5 to 9 coding for a 149 amino acids protein. VISTA global alignments between bovine genomic contigs retrieved from the bovine genome database and the human FHIT region were performed. Conservation was extremely high over a 2 Mb region spanning the whole FHIT locus, including the size of introns. Thus, the bovine FHIT covers about 1.6 Mb compared to 1.5 Mb in man. Expression was analyzed by RT-PCR and Northern blot, and was found to be ubiquitous. Four cDNA isoforms were isolated and sequenced, that originate from an alternative usage of three variants of exon 4, revealing a size very close to the major human FHIT cDNAs. Conclusion A comparative genomic approach allowed to assemble a contig of 78 BACs and to completely annotate a 1.6 Mb region spanning the bovine FHIT gene. The findings confirmed the very high level of conservation between human and bovine genomes and the importance of comparative mapping to speed the annotation process of the recently sequenced bovine genome. The detailed knowledge of the genomic FHIT region will allow to study the role of FHIT in bovine cancerogenesis

Comparative genomic mapping of the bovine Fragile Histidine Triad (FHIT) tumour suppressor gene: characterization of a 2 Mb BAC contig covering the locus, complete annotation of the gene, analysis of cDNA and of physiological expression profiles.

Science.gov (United States)

Uboldi, Cristina; Guidi, Elena; Roperto, Sante; Russo, Valeria; Roperto, Franco; Di Meo, Giulia Pia; Iannuzzi, Leopoldo; Floriot, Sandrine; Boussaha, Mekki; Eggen, André; Ferretti, Luca

2006-05-23

The Fragile Histidine Triad gene (FHIT) is an oncosuppressor implicated in many human cancers, including vesical tumors. FHIT is frequently hit by deletions caused by fragility at FRA3B, the most active of human common fragile sites, where FHIT lays. Vesical tumors affect also cattle, including animals grazing in the wild on bracken fern; compounds released by the fern are known to induce chromosome fragility and may trigger cancer with the interplay of latent Papilloma virus. The bovine FHIT was characterized by assembling a contig of 78 BACs. Sequence tags were designed on human exons and introns and used directly to select bovine BACs, or compared with sequence data in the bovine genome database or in the trace archive of the bovine genome sequencing project, and adapted before use. FHIT is split in ten exons like in man, with exons 5 to 9 coding for a 149 amino acids protein. VISTA global alignments between bovine genomic contigs retrieved from the bovine genome database and the human FHIT region were performed. Conservation was extremely high over a 2 Mb region spanning the whole FHIT locus, including the size of introns. Thus, the bovine FHIT covers about 1.6 Mb compared to 1.5 Mb in man. Expression was analyzed by RT-PCR and Northern blot, and was found to be ubiquitous. Four cDNA isoforms were isolated and sequenced, that originate from an alternative usage of three variants of exon 4, revealing a size very close to the major human FHIT cDNAs. A comparative genomic approach allowed to assemble a contig of 78 BACs and to completely annotate a 1.6 Mb region spanning the bovine FHIT gene. The findings confirmed the very high level of conservation between human and bovine genomes and the importance of comparative mapping to speed the annotation process of the recently sequenced bovine genome. The detailed knowledge of the genomic FHIT region will allow to study the role of FHIT in bovine cancerogenesis, especially of vesical papillomavirus-associated cancers of

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

Science.gov (United States)

Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

2014-07-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O (α-, β-RbUAs) and the anhydrous phase Rb[UO2(AsO3OH)(AsO2(OH)2)] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions.

A Novel Oxidation-Reduction Route for Layer-by-Layer Synthesis of TiO2 Nanolayers and Investigation of Its Photocatalytical Properties

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Konstantin Semishchenko

2014-01-01

Full Text Available Layer-by-layer (LbL synthesis of titanium dioxide was performed by an oxidation-reduction route using a Ti(OH3 colloid and NaNO2 solutions. A model of chemical reactions was proposed based on the results of an investigation of synthesized nanolayers by scanning electron microscopy, electron microprobe analysis and X-ray photoelectron spectroscopy, and studying colloidal solution of Ti(OH3 with laser Doppler microelectrophoresis. At each cycle, negatively charged colloidal particles of [Ti(OH3]HSO4- adsorbed onto the surface of substrate. During the next stage of treatment in NaNO2 solution, the particles were oxidized to Ti(OH4. Photocatalytic activity was studied by following decomposition of methylene blue (MB under UV irradiation. Sensitivity of the measurements was increased using a diffuse transmittance (DT method. The investigation revealed strong photocatalytical properties of the synthesized layers, caused by their high area per unit volume and uniform globular structure.

Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)1.14NbS2 misfit layered compound with aberration-corrected HRTEM

International Nuclear Information System (INIS)

Garbrecht, M.; Spiecker, E.; Tillmann, K.; Jaeger, W.

2011-01-01

Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS) 1.14 NbS 2 misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6 pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice. -- Research Highlights: → Quantitative aberration-corrected HRTEM analysis of atomic column positions in (PbS) 1.14 NbS 2 misfit layered compound reveals tetragonal distortion of the PbS subsystem. → Detailed comparison of multi-slice simulations with the experimental NCSI contrast condition imaging results lead to a high precision (better than 10 pm) for determining the positions of atoms. → Precision in gaining information of local structure at atomic scale is demonstrated, which may not be accessible by means of X-ray and neutron diffraction analysis.

P(O)R2-Directed Enantioselective C-H Olefination toward Chiral Atropoisomeric Phosphine-Olefin Compounds.

Science.gov (United States)

Li, Shi-Xia; Ma, Yan-Na; Yang, Shang-Dong

2017-04-07

An effective synthesis of chiral atropoisomeric biaryl phosphine-olefin compounds via palladium-catalyzed enantioselective C-H olefination has been developed for the first time. The reactions are operationally simple, tolerate wide functional groups, and have a good ee value. Notably, P(O)R 2 not only acts as the directing group to direct C-H activation in order to make a useful ligand but also serves to facilitate composition of the product in a useful manner in this transformation.

MBE growth of few-layer 2H-MoTe2 on 3D substrates

Science.gov (United States)

Vishwanath, Suresh; Sundar, Aditya; Liu, Xinyu; Azcatl, Angelica; Lochocki, Edward; Woll, Arthur R.; Rouvimov, Sergei; Hwang, Wan Sik; Lu, Ning; Peng, Xin; Lien, Huai-Hsun; Weisenberger, John; McDonnell, Stephen; Kim, Moon J.; Dobrowolska, Margaret; Furdyna, Jacek K.; Shen, Kyle; Wallace, Robert M.; Jena, Debdeep; Xing, Huili Grace

2018-01-01

MoTe2 is the least explored material in the Molybdenum-chalcogen family. Molecular beam epitaxy (MBE) provides a unique opportunity to tackle the small electronegativity difference between Mo and Te while growing layer by layer away from thermodynamic equilibrium. We find that for a few-layer MoTe2 grown at a moderate rate of ∼6 min per monolayer, a narrow window in temperature (above Te cell temperature) and Te:Mo ratio exists, where we can obtain pure phase 2H-MoTe2. This is confirmed using reflection high-energy electron diffraction (RHEED), Raman spectroscopy and X-ray photoemission spectroscopy (XPS). For growth on CaF2, Grazing incidence X-ray diffraction (GI-XRD) reveals a grain size of ∼90 Å and presence of twinned grains. In this work, we hypothesis the presence of excess Te incorporation in MBE grown few layer 2H-MoTe2. For film on CaF2, it is based on >2 Te:Mo stoichiometry using XPS as well as 'a' and 'c' lattice spacing greater than bulk 2H-MoTe2. On GaAs, its based on observations of Te crystallite formation on film surface, 2 × 2 superstructure observed in RHEED and low energy electron diffraction, larger than bulk c-lattice spacing as well as the lack of electrical conductivity modulation by field effect. Finally, thermal stability and air sensitivity of MBE 2H-MoTe2 is investigated by temperature dependent XRD and XPS, respectively.

Synthesis, structure and chemical bonding of CaFe2−xRhxSi2 (x=0, 1.32, and 2) and SrCo2Si2

International Nuclear Information System (INIS)

Hlukhyy, Viktor; Hoffmann, Andrea V.; Fässler, Thomas F.

2013-01-01

The finding of superconductivity in Ba 0.6 K 0.4 Fe 2 As 2 put the attention on the investigation of compounds that crystallize with ThCr 2 Si 2 structure type such as AT 2 X 2 (A=alkali/alkaline earth/rare earth element; T=transition metal and X=element of the 13–15th group). In this context the silicides CaFe 2 Si 2 , CaFe 0.68(6) Rh 1.32(6) Si 2 , CaRh 2 Si 2 and SrCo 2 Si 2 have been synthesized by reaction of the elements under an argon atmosphere. Single crystals were obtained by special heat treatment in welded niobium/tantalum ampoules. The compounds were investigated by means of powder and single crystal X-ray diffraction. All compounds crystallize in the ThCr 2 Si 2 -type structure with space group I4/mmm (No. 139): a=3.939(1) Å, c=10.185(1) Å, R 1 =0.045, 85 F 2 values, 8 variable parameters for CaFe 2 Si 2 ; a=4.0590(2) Å, c=9.9390(8) Å, R 1 =0.030, 90 F 2 values, 10 variable parameters for CaFe 0.68(6) Rh 1.32(6) Si 2 ; a=4.0695(1) Å, c=9.9841(3) Å, R 1 =0.031, 114 F 2 values, 9 variable parameters for CaRh 2 Si 2 ; and a=3.974(1) Å, c=10.395(1) Å, R 1 =0.036, 95 F 2 values, 8 variable parameters for SrCo 2 Si 2 . The structure of SrCo 2 Si 2 contains isolated [Co 2 Si 2 ] 2− 2D-layers in the ab-plane whereas in CaFe 2−x Rh x Si 2 the [T 2 Si 2 ] layers (T=Fe and Rh) are interconnected along the c-axis via Si3Si bonds resulting in a three-dimentional (3D) [T 2 Si 2 ] 2− polyanions and therefore belong to the so-called collapsed form of the ThCr 2 Si 2 -type structure. The SrCo 2 Si 2 and CaRh 2 Si 2 are isoelectronic to the parent 122 iron–pnictide superconductors AeFe 2 As 2 (Ae=alkaline earth elements), whereas CaFe 2 Si 2 is a full substituted variant (As/Si) of CaFe 2 As 2 . The crystal chemistry and chemical bonding in the title compounds are discussed in terms of LMTO band structure calculations and a topological analysis using the Electron Localization Function (ELF). - Graphical abstract: The SrCo 2 Si 2 and CaFe 2−x Rh x Si

Synthesis and investigation of aluminium uranium-containing compounds of Al[B5UO6]2[OH]·nH2O (B5=P, As) composition

International Nuclear Information System (INIS)

Chernorukov, N.G.; Sulejmanov, E.V.; Barch, S.V.

2001-01-01

The technique of synthesis of hydroxyuranophosphate and hydroxyuranoarsenate of aluminium is developed. Hydroxyuranophosphates and hydroxyuranoarsenates of aluminium are prepared by reaction of interaction of aqueous solutions of orthophosphoric (orthoarsenic) acid (0.05 mol/l), uranyl nitrate (0.05 mol/l) and aluminium nitrate (0.1 mol/l) at 20 Deg C. Peculiarities of the structure and thermal degradation reactions are studied by the methods of x-ray diffraction, IR spectroscopy, thermography. It is shown that in dependence on outer conditions in the systems Al[PUO 6 ] 2 ·[OH]·nH 2 O and Al[AsUO 6 ] 2 ·[OH]·nH 2 O crystal hydrates with hydrate numbers n=3-11(13) and anhydrous compounds form. The compounds have laminated type of lattice. Two-dimensional layers of [P(As)UO 6 ] ∞ n- are the basis of anion sublattice of these compounds. Aluminium in coordination surrounding of hydroxy groups and water molecules forms cationic sublattice [ru

Surface passivation of nano-textured fluorescent SiC by atomic layer deposited TiO2

DEFF Research Database (Denmark)

Lu, Weifang; Ou, Yiyu; Jokubavicius, Valdas

2016-01-01

Nano-textured surfaces have played a key role in optoelectronic materials to enhance the light extraction efficiency. In this work, morphology and optical properties of nano-textured SiC covered with atomic layer deposited (ALD) TiO2 were investigated. In order to obtain a high quality surface fo...

Structural investigation of the ZnSe(001)-c(2×2) surface

DEFF Research Database (Denmark)

Weigand, W.; Müller, A.; Kilian, L.

2003-01-01

Zinc selenide is a model system for II-VI compound semiconductors. The geometric structure of the clean (001)-c(2x2) surface has recently been the subject of intense debate. We report here a surface x-ray-diffraction study on the ZnSe(001)-c(2x2) surface performed under ultrahigh vacuum using...

Improved conductivity of infinite-layer LaNiO2 thin films by metal organic decomposition

International Nuclear Information System (INIS)

Ikeda, Ai; Manabe, Takaaki; Naito, Michio

2013-01-01

Highlights: •LaNiO 2 films were synthesized by metal organic decomposition and topotactic reduction. •Room-temperature resistivity as low as 0.6 mΩ cm was achieved for infinite-layer LaNiO 2 . •Lattice matched substrates are important in obtaining high conductivity. -- Abstract: Infinite-layer LaNiO 2 thin films were synthesized by metal organic decomposition and subsequent topotactic reduction in hydrogen, and their transport properties were investigated. LaNiO 2 is isostructural to SrCuO 2 , the parent compound of high-T c Sr 0.9 La 0.1 CuO 2 with T c = 44 K, and has 3d 9 configuration, which is very rare in oxides but common to high-T c copper oxides. The bulk synthesis of LaNiO 2 is not easy, but we demonstrate in this article that the thin-film synthesis of LaNiO 2 is rather easy, thanks to a large-surface-to-volume ratio, which makes oxygen diffusion prompt. Our refined synthesis conditions produced highly conducting films of LaNiO 2 . The resistivity of the best film is as low as 640 μΩ cm at 295 K and decreases with temperature down to 230 K but it shows a gradual upturn at lower temperatures

Comparative neuropharmacology of N-(2-methoxybenzyl)-2,5-dimethoxyphenethylamine (NBOMe) hallucinogens and their 2C counterparts in male rats.

Science.gov (United States)

Elmore, Joshua S; Decker, Ann M; Sulima, Agnieszka; Rice, Kenner C; Partilla, John S; Blough, Bruce E; Baumann, Michael H

2018-03-01

2,5-Dimethoxyphenethylamines (2C compounds) are 5-HT 2A/2C receptor agonists that induce hallucinogenic effects. N-methoxybenzylation of 2C compounds markedly increases their affinity for 5-HT 2A receptors, and two such analogs, 2-(4-chloro-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25C-NBOMe) and 2-(4-iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOMe), have emerged in recreational drug markets. Here, we investigated the neuropharmacology of 25C-NBOMe and 25I-NBOMe in rats, as compared to their 2C analogs and the prototypical 5-HT 2A/2C agonist 1-(4-iodo-2,5-dimethoxyphenyl)propan-2-amine (DOI). Compounds were tested in vitro using 5-HT 2A receptor binding and calcium mobilization assays. For in vivo experiments, 25C-NBOMe (0.01-0.3 mg/kg), 25I-NBOMe (0.01-0.3 mg/kg), 2-(4-chloro-2,5-dimethoxyphenyl)ethanamine (2C-C) (0.1-3.0 mg/kg), 2-(4-iodo-2,5-dimethoxyphenyl)ethanamine (2C-I) (0.1-3.0 mg/kg) and DOI (0.03-1.0 mg/kg) were administered subcutaneously (sc) to male rats, and 5-HT 2A -mediated behaviors were assessed. NBOMes displayed higher affinity for 5-HT 2A receptors than their 2C counterparts but were substantially weaker in functional assays. 25C-NBOMe and 25I-NBOMe were much more potent at inducing wet dog shakes (WDS) and back muscle contractions (BMC) when compared to 2C-C and 2C-I. Pretreatment with the selective 5-HT 2A antagonist (R)-(2,3-dimethoxyphenyl){1-[2-(4-fluorophenyl)ethyl]-4-piperidinyl}methanol (M100907) reversed behaviors produced by all agonists. Interestingly, binding affinities at the 5-HT 2A receptor were significantly correlated with potencies to induce BMC but not WDS. Our findings show that NBOMes are highly potent 5-HT 2A agonists in rats, similar to effects in mice, and consistent with the reported hallucinogenic effects in human users. Copyright © 2018. Published by Elsevier Ltd.

Facial One-Pot Synthesis of D 3h Symmetric Bicyclocalix[2]arene[2]triazines and Their Layered Comb Self-Assembly

KAUST Repository

Chen, Yin

2017-11-23

A number of D3h symmetric bicyclocalix[2]arene[2]triazine core compounds were synthesized via a general and good-yielding (43-48% yield) facile protocol starting from cyanuric halides, phloroglucinol and K2CO3 under very mild reaction conditions. These cage-like compounds are tolerate with different reaction conditions and can be derived with other functional groups in high yield. The X-ray crystal structures show these compounds have slightly distorted D3h symmetric structures. Due to the unique molecular topological structure, bicyclocalix[2]arene[2]triazine molecules form unique layered comb networks when hydrogen bond groups exist (such as CO2H, B(OH)2), which represent a new kind of building block unit for supramolecular architectures.

Clostridium botulinum C2 toxin. Identification of the binding site for chloroquine and related compounds and influence of the binding site on properties of the C2II channel.

Science.gov (United States)

Neumeyer, Tobias; Schiffler, Bettina; Maier, Elke; Lang, Alexander E; Aktories, Klaus; Benz, Roland

2008-02-15

Clostridium botulinum C2 toxin belongs to the family of binary AB type toxins that are structurally organized into distinct enzyme (A, C2I) and binding (B, C2II) components. The proteolytically activated 60-kDa C2II binding component is essential for C2I transport into target cells. It oligomerizes into heptamers and forms channels in lipid bilayer membranes. The C2II channel is cation-selective and can be blocked by chloroquine and related compounds. Residues 303-330 of C2II contain a conserved pattern of alternating hydrophobic and hydrophilic residues, which has been implicated in the formation of two amphipathic beta-strands involved in membrane insertion and channel formation. In the present study, C2II mutants created by substitution of different negatively charged amino acids by alanine-scanning mutagenesis were analyzed in artificial lipid bilayer membranes. The results suggested that most of the C2II mutants formed SDS-resistant oligomers (heptamers) similar to wild type. The mutated negatively charged amino acids did not influence channel properties with the exception of Glu(399) and Asp(426), which are probably localized in the vestibule near the channel entrance. These mutants show a dramatic decrease in their affinity for binding of chloroquine and its analogues. Similarly, F428A, which represents the Phi-clamp in anthrax protective antigen, was mutated in C2II in several other amino acids. The C2II mutants F428A, F428D, F428Y, and F428W not only showed altered chloroquine binding but also had drastically changed single channel properties. The results suggest that amino acids Glu(399), Asp(426), and Phe(428) have a major impact on the function of C2II as a binding protein for C2I delivery into target cells.

Synthesis and crystal structure of Mg0.5NbO2: An ion-exchange reaction with Mg2+ between trigonal [NbO2]- layers

Science.gov (United States)

Miura, Akira; Takei, Takahiro; Kumada, Nobuhiro

2013-01-01

A new layered niobate, Mg0.5NbO2, was synthesized from LiNbO2 through a cation-exchange reaction with Mg2+ at 450-550 °C. This is the first example of a topotactic reaction with an aliovalent cation between trigonal [NbO2]- layers. It is proposed to be isostructural with LiNbO2 (space group; P63/mmc) with lattice parameters of a=2.9052(6) Å, c=10.625(15) Å. The lattice parameters and formation energy of Mg0.5NbO2 crystallized in LiNbO2 form and other layered CaNb2O4 one were calculated by density functional theory.

Interdiffusion studies on high-Tc superconducting YBa2Cu3O7-δ thin films on Si(111) with a NiSi2/ZrO2 buffer layer

DEFF Research Database (Denmark)

Aarnink, W.A.M.; Blank, D.H.A.; Adelerhof, D.J.

1991-01-01

Interdiffusion studies on high-T(c) superconducting YBa2Cu3O7-delta thin films with thickness in the range of 2000-3000 angstrom, on a Si(111) substrate with a buffer layer have been performed. The buffer layer consists of a 400 angstrom thick epitaxial NiSi2 layer covered with 1200 angstrom...... of polycrystalline ZrO2. YBa2Cu3O7-delta films were prepared using laser ablation. The YBa2Cu3O7-delta films on the Si/NiSi2/ZrO2 substrates are of good quality; their critical temperatures T(c,zero) and T(c,onset) have typical values of 85 and 89 K, respectively. The critical current density j(c) at 77 K equaled 4...... x 10(4) A/cm2. With X-ray analysis (XRD), only c-axis orientation has been observed. The interdiffusion studies, using Rutherford backscattering spectrometry (RBS) and scanning Auger microscopy (SAM) show that the ZrO2 buffer layer prevents severe Si diffusion to the YBa2Cu3O7-delta layer, the Si...

(3-Benzoyl-1,7,7-trimethylbicyclo[2.2.1]heptan-2-olato-κ2O,Obis[2-(2-pyridylphenyl-κ2C1,N]iridium(III

Directory of Open Access Journals (Sweden)

Kaijun Luo

2011-11-01

Full Text Available The title compound, [Ir(C11H8N2(C17H19O2], has an octahedral coordination geometry around the IrIII atom, retaining the cis-C,C,trans–N,N chelate disposition of the two 2-phenylpyridine ligands. The chelate rings are nearly mutually perpendicular [the interplanar angles range from 85.48 (17 to 89.17 (19°]. The two 2-(2-pyridylphenyl ligands are approximately planar, with the plane of the phenyl ring being inclined to that of the pyridine ring by 2.3 (3 and 5.1 (3° in the two ligands. The interplanar angle between the phenyl ring in 3-benzoyl-camphor and the IrO2C3 chelate ring is 35.5 (2°.

Zn2(TeO3Br2

Directory of Open Access Journals (Sweden)

Mats Johnsson

2008-05-01

Full Text Available Single crystals of dizinc tellurium dibromide trioxide, Zn2(TeO3Br2, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound has a layered crystal structure in which the building units are [ZnO4Br] distorted square pyramids, [ZnO2Br2] distorted tetrahedra, and [TeO3E] tetrahedra (E being the 5s2 lone pair of Te4+ joined through sharing of edges and corners to form layers of no net charge. Bromine atoms and tellurium lone pairs protrude from the surfaces of each layer towards adjacent layers. This new compound Zn2(TeO3Br2 is isostructural with the synthetic compounds Zn2(TeO3Cl2, CuZn(TeO32, Co2(TeO3Br2 and the mineral sophiite, Zn2(SeO3Cl2.

Crystal structures of [Ln(NO33(μ2-bpydo2], where Ln = Ce, Pr or Nd, and bpydo = 4,4′-bipyridine N,N′-dioxide: layered coordination networks containing 44 grids

Directory of Open Access Journals (Sweden)

Michael L. Stromyer

2016-01-01

Full Text Available Three isostructural coordination networks of Ce, Pr, and Nd nitrate with 4,4′-bipyridine N,N′-dioxide (bpydo are reported, namely poly[[tris(nitrato-κ2O,O′cerium(III]-bis(μ2-4,4′-bipyridine N,N′-dioxide-κ2N:N′], [Ce(NO33(C10H8N2O22], poly[[tris(nitrato-κ2O,O′praeseodymium(III]-bis(μ2-4,4′-bipyridine N,N′-dioxide-κ2N:N′], [Pr(NO33(C10H8N2O22], and poly[[tris(nitrato-κ2O,O′neodymium(III]-bis(μ2-4,4′-bipyridine N,N′-dioxide-κ2N:N′], [Nd(NO33(C10H8N2O22]. All three compounds are isostructural to the previously reported La analogue. The asymmetric unit of [Ln(NO33(μ2-bpydo2] contains one lanthanide cation, two bpydo ligands, and three nitrate anions. Both bpydo ligands act as end-to-end μ2-bridges and display nearly ideal cis and gauche conformations, respectively. The bpydo ligands link the ten-coordinate LnIII cations, forming interdigitating 44 grid-like layers extending parallel to (-101, where interdigitation of layers is promoted by C—H...O interactions between nitrate anions and bpydo ligands. The interdigitated layers are linked to sets of neighboring layers via further C—H...O and π–π interactions.

Synthesis of [PtCl2(4,4'-dialkoxy-2,2'-bipyridine)] complexes and their in vitro anticancer properties.

Science.gov (United States)

Vo, Van; Tanthmanatham, Ontida; Han, Haesook; Bhowmik, Pradip K; Spangelo, Bryan L

2013-08-01

A series of [Pt(II)Cl2(4,4'-dialkoxy-2,2'-bipyridine)] complexes of the general formula of [Pt(II)Cl2(4,4'-bis(RO)-2,2'-bipyridine)] (where R = -(CH2)n-1CH3, n = 2-6, 8) were synthesized and characterized using (1)H NMR, (13)C NMR spectroscopy, elemental analysis, mass spectroscopy, and differential scanning calorimetry measurements. The in vitro anti-proliferative activities of these compounds were evaluated against human cancer cell lines A549 (lung adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), and MDA-MB-435 (melanoma) using the MTS cell proliferation assay. Several Pt(II) coordination compounds were found to have greatly enhanced activity compared to cisplatin after a one hour treatment in all cell lines tested. A structure-activity relationship was observed, that is, the activity increases as the carbon chain length of the alkyl group increases. The activity was maximum when the carbon chain length reached four or five carbons and decreased with the longer carbon chain length. Fluorescence microscopy and flow cytometry data indicate that the main mode of cell death is through apoptosis with some necrotic responses.

Fabrication of hierarchical flower-like porous ZnO nanostructures from layered ZnC2O4·3Zn(OH)2 and gas sensing properties

International Nuclear Information System (INIS)

Cui, Jiashan; Sun, Jianbo; Liu, Xin; Li, Jinwei; Ma, Xinzhi; Chen, Tingting

2014-01-01

ZnO materials with porous and hierarchical flower-like structure were synthesized through mild hydrothermal and simple calcination approach, in which the flower-like layered zinc oxalate hydroxide (ZnC 2 O 4 ·3Zn(OH) 2 ) precursor was first synthesized and then calcined at 600 °C. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopic (TEM), Brunauer–Emmett–Teller (BET) and thermogravimetric (TG) analysis. We proposed the possible growth mechanism of the material via studying the time evolution experiment results. In the process of reaction, oxalic acid as a structure-directing agent hydrolyzed and then formed primarily sheets-like intermediate ZnC 2 O 4 ·2H 2 O. Hexamethylenetetramine (HMT) as surfactant, with directional adsorption, leads to the formation of layered zinc oxalate hydroxide precursor. Furthermore, the gas sensitivity also can be characterized, whose results indicated that the synthesized materials had a preferable selectivity to ethanol gas. The fast response rate and reversible performance can be attributed to the produced greater specific surface area produced, which was caused by the porous and hierarchical flower-like structure.

Fabrication of hierarchical flower-like porous ZnO nanostructures from layered ZnC2O4·3Zn(OH)2 and gas sensing properties

Science.gov (United States)

Cui, Jiashan; Sun, Jianbo; Liu, Xin; Li, Jinwei; Ma, Xinzhi; Chen, Tingting

2014-07-01

ZnO materials with porous and hierarchical flower-like structure were synthesized through mild hydrothermal and simple calcination approach, in which the flower-like layered zinc oxalate hydroxide (ZnC2O4·3Zn(OH)2) precursor was first synthesized and then calcined at 600 °C. The obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopic (TEM), Brunauer-Emmett-Teller (BET) and thermogravimetric (TG) analysis. We proposed the possible growth mechanism of the material via studying the time evolution experiment results. In the process of reaction, oxalic acid as a structure-directing agent hydrolyzed and then formed primarily sheets-like intermediate ZnC2O4·2H2O. Hexamethylenetetramine (HMT) as surfactant, with directional adsorption, leads to the formation of layered zinc oxalate hydroxide precursor. Furthermore, the gas sensitivity also can be characterized, whose results indicated that the synthesized materials had a preferable selectivity to ethanol gas. The fast response rate and reversible performance can be attributed to the produced greater specific surface area produced, which was caused by the porous and hierarchical flower-like structure.

Cu-O network dependence of optical charge-transfer gaps and spin-pair excitations in single-CuO2-layer compounds

International Nuclear Information System (INIS)

Tokura, Y.; Koshihara, S.; Arima, T.; Takagi, H.; Ishibashi, S.; Ido, T.; Uchida, S.

1990-01-01

Spectra of optical conductivity and magnon Raman scattering have been investigated in single crystals of a parent family of cuprate superconductors with various types of Cu-O single-layer networks. The analysis of the spectra shows the systematic dependence of the charge-transfer gaps and covalent character of Cu-O bonds on the pattern of the Cu-O network, while the spin-exchange energy is rather convergent for all the single-CuO 2 -sheet compounds

Crystal Structure and Antiferromagnetic Ordering of Quasi-2D [Cu(HF2)(pyz)2]TaF6 (pyz=pyrazine)

Science.gov (United States)

Manson, J. L.; Schlueter, J. A.; McDonald, R. D.; Singleton, J.

2010-04-01

The crystal structure of the title compound was determined by X-ray diffraction at 90 and 295 K. Copper(II) ions are coordinated to four bridging pyz ligands to form square layers in the ab-plane. Bridging HF2- ligands join the layers together along the c-axis to afford a tetragonal, three-dimensional (3D) framework that contains TaF6- anions in every cavity. At 295 K, the pyz rings lie exactly perpendicular to the layers and cooling to 90 K induces a canting of those rings. Magnetically, the compound exhibits 2D antiferromagnetic correlations within the 2D layers with an exchange interaction of -13.1(1) K. Weak interlayer interactions, as mediated by Cu-F-H-F-Cu, leads to long-range magnetic order below 4.2 K. Pulsed-field magnetization data at 0.5 K show a concave curvature with increasing B and reveal a saturation magnetization at 35.4 T.

Search for compounds contributing to onion-like off-flavor in beer and investigation of the cause of the flavor.

Science.gov (United States)

Noba, Shigekuni; Yako, Nana; Kobayashi, Minoru; Masuda, Susumu; Watanabe, Tetsuya

2017-10-01

Onion-like off-flavor is a highly undesirable property in beer. Although several compounds that impart onion-like odors have been identified, the individual contribution of these compounds to the onion-like off-flavor in beer is not clear. In the present study, we searched for compounds that impart an onion-like odor by gas chromatography (GC)-olfactometry. The analysis of several types of beer revealed that 2-mercapto-3-methyl-1-butanol (2M3MB) and 3-mercapto-3-methyl-1-butanol (3M3MB) were possible causative compounds. Based on the difference threshold values in beer (0.13 ng/mL for 2M3MB and 17.5 ng/mL for 3M3MB) and the quantification values of these compounds in beer samples, only 2M3MB was considered to contribute to the onion-like off-flavor in beer. A further formation factor analysis of 2M3MB revealed that 2M3MB was formed in hopped wort after fermentation, and that the concentration of 2M3MB increased following the hot aeration treatment of wort. These results suggest that preventing the hot aeration of wort is a key factor for reducing 2M3MB levels in beer. In a previous report, 3-methyl-2-buten-1-ol (3MBol) was speculated to be the precursor of 2M3MB and 3M3MB; however, the results of the present quantification analysis and wort addition tests indicate that 3MBol did not contribute to the formation of 2M3MB in the brewing process and that unknown precursors of 2M3MB originated in wort. Identifying the precursor of 2M3MB may facilitate elucidation of the mechanism of 2M3MB formation. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Growth and magnetotransport properties of epitaxial films of the layered perovskite La2-2xSr1+2xMn2O7

International Nuclear Information System (INIS)

Philipp, J.B.; Alff, L.; Gross, R.; Klein, J.; Recher, C.

2002-01-01

Epitaxial thin films of the bilayered perovskite La 2-2x Sr 1+2x Mn 2 O 7 (x=0.3, 0.4) have been grown by laser molecular beam epitaxy on NdGaO 3 substrates. Magnetotransport measurements with the current in the ab-plane and along the c-axis direction showed an intrinsic c-axis tunneling magnetoresistance effect associated with nonlinear current-voltage-characteristics for the x=0.3 compound. Besides the colossal magnetoresistance effect around the Curie temperature T C , at temperatures below about 40 K an additional high-field magnetoresistance was found most likely due to a strain and disorder induced re-entrant spin glass state in both the x=0.3 and 0.4 compounds. Our experiments show that the substrate induced coherency strain in the high quality epitaxial films results in magnetotransport properties that show markedly different behavior from those of single crystals. (orig.)

(C6H16N2)Zn3(HPO3)4H2O: a new layered zinc phosphite templated by diprotonated trans-1,4-diaminocyclohexane

International Nuclear Information System (INIS)

Wang Yu; Yu Jihong; Li Yi; Du Yu; Xu Ruren; Ye Ling

2003-01-01

Employing trans-1,4-diaminocyclohexane (trans-1,4-DACH) as a template, a new two-dimensional layered zinc phosphite (C 6 H 16 N 2 )Zn 3 (HPO 3 ) 4 H 2 O (1) has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group P2 1 /n with a=10.458(2) A, b=14.720(3) A, c=13.079(3) A, β=97.93(3) deg. , V=1994.1(7) A 3 , Z=4, R 1 =0.0349 (I>2σ(I)) and wR 2 =0.0605 (all data). The inorganic layer is built up by alternation of ZnO 4 tetrahedra and HPO 3 pseudo pyramids forming a 4.6.8-net. The sheet is featured by a series of capped six-membered rings. The diprotonated trans-1,4-DACH molecules reside in the interlayer region and interact with the inorganic network through H-bonds

Magnetic studies on Layered solid solution Lix(Ni0.4Mn0.6)2-xO2

Science.gov (United States)

Nakao, K.; Nakamura, T.; Yamada, Y.; Koshiba, N.

2011-05-01

Lix(Ni0.4Mn0.6)2-xO2 (1.09hydroxide as raw materials. All the compounds have a layered rock-salt structure, and the cation mixing degree (Ni2+ occupancy in the Li-layer) decreases with an increase in x. From the low-temperature magnetic measurement, they all have negative Weiss temperature and spontaneous magnetization, that is, they are ferromagnetic materials. Both the Curie temperature and the spontaneous magnetization at 4.2K decrease with an increase in x. These magnetic variations are attributed to the lowering of the cation mixing degree: the magnetic interaction network turns to two-dimensional one with the loss of the inert-layer coupling. These situations may be considered semi-quantitatively using the ferromagnetic cluster model. Additionally, the cation mixing degree has an influence on their electrochemical properties such as cycle fading and rate capability.

Influence of boron vacancies on phase stability, bonding and structure of MB2 (M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) with AlB2 type structure

International Nuclear Information System (INIS)

Dahlqvist, Martin; Rosen, Johanna; Jansson, Ulf

2015-01-01

Transition metal diborides in hexagonal AlB 2 type structure typically form stable MB 2 phases for group IV elements (M  =  Ti, Zr, Hf). For group V (M  =  V, Nb, Ta) and group VI (M  =  Cr, Mo, W) the stability is reduced and an alternative hexagonal rhombohedral MB 2 structure becomes more stable. In this work we investigate the effect of vacancies on the B-site in hexagonal MB 2 and its influence on the phase stability and the structure for TiB 2 , ZrB 2 , HfB 2 , VB 2 , NbB 2 , TaB 2 , CrB 2 , MoB 2 , and WB 2 using first-principles calculations. Selected phases are also analyzed with respect to electronic and bonding properties. We identify trends showing that MB 2 with M from group V and IV are stabilized when introducing B-vacancies, consistent with a decrease in the number of states at the Fermi level and by strengthening of the B–M interaction. The stabilization upon vacancy formation also increases when going from M in period 4 to period 6. For TiB 2 , ZrB 2 , and HfB 2 , introduction of B-vacancies have a destabilizing effect due to occupation of B–B antibonding orbitals close to the Fermi level and an increase in states at the Fermi level. (paper)

Zn2(TeO3)Br2

Science.gov (United States)

Zhang, Dong; Johnsson, Mats

2008-01-01

Single crystals of dizinc tellurium dibromide trioxide, Zn2(TeO3)Br2, were synthesized via a transport reaction in sealed evacuated silica tubes. The compound has a layered crystal structure in which the building units are [ZnO4Br] distorted square pyramids, [ZnO2Br2] distorted tetra­hedra, and [TeO3 E] tetra­hedra (E being the 5s 2 lone pair of Te4+) joined through sharing of edges and corners to form layers of no net charge. Bromine atoms and tellurium lone pairs protrude from the surfaces of each layer towards adjacent layers. This new compound Zn2(TeO3)Br2 is isostructural with the synthetic compounds Zn2(TeO3)Cl2, CuZn(TeO3)2, Co2(TeO3)Br2 and the mineral sophiite, Zn2(SeO3)Cl2. PMID:21202162

Atomic layer-deposited Al–HfO{sub 2}/SiO{sub 2} bi-layers towards 3D charge trapping non-volatile memory

Energy Technology Data Exchange (ETDEWEB)

Congedo, Gabriele, E-mail: gabriele.congedo@mdm.imm.cnr.it; Wiemer, Claudia; Lamperti, Alessio; Cianci, Elena; Molle, Alessandro; Volpe, Flavio G.; Spiga, Sabina, E-mail: sabina.spiga@mdm.imm.cnr

2013-04-30

A metal/oxide/high-κ dielectric/oxide/silicon (MOHOS) planar charge trapping memory capacitor including SiO{sub 2} as tunnel oxide, Al–HfO{sub 2} as charge trapping layer, SiO{sub 2} as blocking oxide and TaN metal gate was fabricated and characterized as test vehicle in the view of integration into 3D cells. The thin charge trapping layer and blocking oxide were grown by atomic layer deposition, the technique of choice for the implementation of these stacks into 3D structures. The oxide stack shows a good thermal stability for annealing temperature of 900 °C in N{sub 2}, as required for standard complementary metal–oxide–semiconductor processes. MOHOS capacitors can be efficiently programmed and erased under the applied voltages of ± 20 V to ± 12 V. When compared to a benchmark structure including thin Si{sub 3}N{sub 4} as charge trapping layer, the MOHOS cell shows comparable program characteristics, with the further advantage of the equivalent oxide thickness scalability due to the high dielectric constant (κ) value of 32, and an excellent retention even for strong testing conditions. Our results proved that high-κ based oxide structures grown by atomic layer deposition can be of interest for the integration into three dimensionally stacked charge trapping devices. - Highlights: ► Charge trapping device with Al–HfO{sub 2} storage layer is fabricated and characterized. ► Al–HfO{sub 2} and SiO{sub 2} blocking oxides are deposited by atomic layer deposition. ► The oxide stack shows a good thermal stability after annealing at 900 °C. ► The device can be efficiently programmed/erased and retention is excellent. ► The oxide stack could be used for 3D-stacked Flash non-volatile memories.

Structural characterization of AgGaTe{sub 2} layers grown on a- and c-sapphire substrates by a closed space sublimation method

Energy Technology Data Exchange (ETDEWEB)

Uruno, Aya; Usui, Ayaka [Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051 (Japan)

2014-07-15

AgGaTe{sub 2} layers were grown on a- and c-plane sapphire substrates by a closed space sublimation method with varying the source temperature. Grown films were evaluated by θ -2θ and pole figure measurements of X-ray diffraction. AgGaTe{sub 2} layers were grown to have strong preference for the (103) orientation. However, it was cleared the Ag{sub 5}Te{sub 3} was formed along with the AgGaTe{sub 2} when the layer was grown on c-plane sapphire. The orientation of the film was analyzed by using the pole figure, and resulted in AgGaTe{sub 2} without Ag{sub 5}Te{sub 3} layers could be grown on a-plane sapphire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Nido-Carborane building-block reagents. 2. Bulky-substituent (alkyl)2C2B4H6 derivatives and (C6H5)2C2B4H6: synthesis and properties

International Nuclear Information System (INIS)

Boyter, H.A. Jr.; Grimes, R.N.

1988-01-01

The preparation and chemistry of nido-2,3-R 2 C 2 C 2 B 4 H 6 carboranes in which R is n-butyl, isopentyl, n-hexyl, and phenyl was investigated in order to further assess the steric and electronic influence of the R groups on the properties of the nido-C 2 B 4 cage, especially with respect to metal complexation at the C 2 B 3 face and metal-promoted oxidative fusion. The three dialkyl derivatives were prepared from the corresponding dialkylacetylenes via reaction with B 5 H 9 and triethylamine, but the diphenyl compound could not be prepared in this manner and was obtained instead in a thermal reaction of B 5 H 9 with diphenylacetylene in the absence of amine. All four carboranes are readily bridge-deprotonated by NaH in THF, and the anions of the dialkyl species, on treatment with FeCl 2 and air oxidation, generate the respective R 4 C 4 B 8 H 8 carborane fusion products were R = n-C 4 H 9 , i-C 5 H 11 or n-C 6 H 13 . The diphenylcarborane anion Ph 2 C 2 B 4 H 5 - did not form detectable metal complexes with Fe 2+ , Co 2+ , or Ni 2+ , and no evidence of a Ph 4 C 4 B 8 H 8 fusion product has been found. Treatment of Ph 2 C 2 B 4 H 6 with Cr(CO) 6 did not lead to metal coordination of the phenyl rings, unlike (PhCH 2 ) 2 C 2 B 4 H 6 , which had previously been shown to form mono- and bis(tricarbonylchromium) complexes. However, the reaction of Ph 2 C 2 B 4 H 5 - , CoCl 2 , and (PhPCH 2 ) 2 did give 1,1-(Ph 2 PCH 2 ) 2 -1-Cl-1,2,3-Co(Ph 2 C 2 B 4 H 4 ), the only case in which metal complexation of the diphenylcarborane was observed. 14 references, 3 figures, 3 tables

Phase equilibria and crystal chemistry in the ternary system BaO-TiO 2-Nb 2O 5. II. New barium polytitanates with <5 mole% Nb 2O 5

Science.gov (United States)

Roth, R. S.; Ettlinger, L. D.; Parker, H. S.

1987-06-01

Four new compounds were found in the BaO-TiO 2-Nb 2O 5 system, each containing orth ≈ 9.9A˚, b mon ≈ a orth ≈ 17A˚). Ba 14Ti 40Nb 2O 99 is a 20-layer orthorhombic phase, Cmc*, withc ≈ 46.86A˚. Ba 10Ti 28Nb 2O 72 is a 7-layer monoclinic phase, C2m, c ≈ 16.72A˚, β ≈ 101.2°. Ba 18Ti 54Nb 2O 132 is a 13-layer monoclinic phase, C2m, c ≈ 30.65A˚, β ≈ 96°. The compositions were derived by analogy to the layers in Ba 4Ti 13 O 30 and Ba 6Ti 17O 40 and are consistent with limited phase equilibria data.

Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis.

Science.gov (United States)

Yu, Bang-Wei; Li, Jin-Long; Guo, Bin-Bin; Fan, Hui-Min; Zhao, Wei-Min; Wang, He-Yao

2016-11-01

Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1-9) isolated from the leaves of Gynura nepalensis for their protective effect against H 2 O 2 -induced H9c2 cardiomyoblast damage and explored the underlying mechanisms. H9c2 cardiomyoblasts were exposed to H 2 O 2 (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H 2 DCFDA. The expression levels of relevant proteins were detected using Western blot analysis. Exposure to H 2 O 2 markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H 2 O 2 -induced cell death. Pretreatment with compound 6 (1.56-100 μmol/L) dose-dependently alleviated all the H 2 O 2 -induced detrimental effects. Moreover, exposure to H 2 O 2 significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H 2 O 2 also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H 2 O 2 -induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H 2 O 2 -induced phosphorylation of JNK and ERK but not that of p38. Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2

Zintl-phases with layer anions: preparation and crystal structures of the isotypic compounds SrSn sub 2 As sub 2 and Sr sub 0. 87 Ba sub 0. 13 Sn sub 2 As sub 2 and a single crystal structure determination of KSnSb. Zintl-Phasen mit Schichtanionen: Darstellung und Kristallstrukturen der isotypen Verbindungen SrSn sub 2 As sub 2 und Sr sub 0,87 Ba sub 0,13 Sn sub 2 As sub 2 sowie eine Einkristallstrukturbestimmung von KSnSb

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, B; Klein, J [Abt. 2 fuer Anorganische Chemie, Technische Hochschule Darmstadt (Germany)

1991-06-01

The metallic reflecting compounds SrSn{sub 2}As{sub 2} and Sr{sub 0.87}Ba{sub 0.13}Sn{sub 2}As{sub 2} were prepared from the melt, they crystallize in the trigonal rhombohedral system (space group R3m, Z = 3) with lattice constants see ''Inhaltsuebersicht''. In the crystal structure of the isotypic compounds threebonded Sn atoms and threebonded As atoms together form puckered layers which are isostructural to grey As. The mean values of the bond lengths Sn -- As are 277.6 pm (SrSn{sub 2}As{sub 2}) and 279.1 pm (Sr{sub 0.87}Ba{sub 0.13}Sn{sub 2}As{sub 2}) resp. Along (001) the alkaline earth atoms occupy the octahedral interstices of As atoms between each second SnAs layer. The single crystal structure determination of KSnSb confirms the results of the X-ray powder analysis, but leads to slightly different values for the bond lengths.

Crystalline electric fields and magnetic properties of single-crystalline RNiC2 compounds R=Ho, Er and Tm

International Nuclear Information System (INIS)

Koshikawa, Y.; Onodera, H.; Kosaka, M.; Yamauchi, H.; Ohashi, M.; Yamaguchi, Y.

1997-01-01

Magnetometric investigations were performed on single-crystalline HoNiC 2 , ErNiC 2 and TmNiC 2 compounds. Susceptibility of HoNiC 2 shows no anomaly around T N , but a clear cusp appears at T t =2.9 K. Magnetization curves reveal that the anisotropy is relatively weak and that the Ho moments align not along any crystallographic axis. In addition to T N =8.5 K of ErNiC 2 , a new order-order transition at T t =3.6 K has been found. Although the Er moments align along the a-axis between T t and T N , it seems certain that the small moment-components along the b- and c-axes come into existence below T t . TmNiC 2 with T N =5.5 K has a strong uniaxial anisotropy along the a-axis. These results are discussed on the basis of competitions between the magnetic interactions and the crystal field effect which changes anomalously by the replacement of rare earth element. It has been found that the drastic change of crystal field occurs between HoNiC 2 and ErNiC 2 without any corresponding structural change. (orig.)

2-[({2-[(2-Hydroxy-5-methoxybenzylideneamino]ethyl}iminomethyl]-4-methoxyphenol

Directory of Open Access Journals (Sweden)

Ali Ourari

2012-06-01

Full Text Available The asymmetric unit of the title compound, C18H20N2O4, contains one-half molecule with an inversion center located at the centroid of the molecule. In the crystal, molecules are linked by C—H...π interactions, forming layers parallel to (101. An intramolecular O—H...N hydrogen bond also occurs.

Elastic constants of the C15 laves phase compound NbCr2

International Nuclear Information System (INIS)

Chu, F.; He, Y.; Thoma, D.J.; Mitchell, T.E.

1995-01-01

Elastic properties of a solid are important because they relate to various fundamental solid-state phenomena such as interatomic potentials, equations of state, and phonon spectra. Elastic properties are also linked thermodynamically with specific heat, thermal expansion, Debye temperature, and Gruneisen parameter. Most important, knowledge of elastic constants is essential for many practical applications related to the mechanical properties of a solid as well: load-deflection, thermoelastic stress, internal strain (residual stress), sound velocities, dislocation core structure, and fracture toughness. In order to understand better the physical properties and deformation behavior of the C15 compound NbCr 2 , the authors have studied its elastic properties in this paper. In Section 2, the experimental methods are described, including the preparation of the sample and the measurement of the elastic constants. In Section 3, the experimental results are presented and the implications of these experimental results are discussed. Conclusions are drawn in Section 4

Improved conductivity of infinite-layer LaNiO{sub 2} thin films by metal organic decomposition

Energy Technology Data Exchange (ETDEWEB)

Ikeda, Ai [Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan); Research Fellow of the Japan Society for the Promotion of Science (Japan); Manabe, Takaaki [National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan); Naito, Michio, E-mail: minaito@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan)

2013-12-15

Highlights: •LaNiO{sub 2} films were synthesized by metal organic decomposition and topotactic reduction. •Room-temperature resistivity as low as 0.6 mΩ cm was achieved for infinite-layer LaNiO{sub 2}. •Lattice matched substrates are important in obtaining high conductivity. -- Abstract: Infinite-layer LaNiO{sub 2} thin films were synthesized by metal organic decomposition and subsequent topotactic reduction in hydrogen, and their transport properties were investigated. LaNiO{sub 2} is isostructural to SrCuO{sub 2}, the parent compound of high-T{sub c} Sr{sub 0.9}La{sub 0.1}CuO{sub 2} with T{sub c} = 44 K, and has 3d{sup 9} configuration, which is very rare in oxides but common to high-T{sub c} copper oxides. The bulk synthesis of LaNiO{sub 2} is not easy, but we demonstrate in this article that the thin-film synthesis of LaNiO{sub 2} is rather easy, thanks to a large-surface-to-volume ratio, which makes oxygen diffusion prompt. Our refined synthesis conditions produced highly conducting films of LaNiO{sub 2}. The resistivity of the best film is as low as 640 μΩ cm at 295 K and decreases with temperature down to 230 K but it shows a gradual upturn at lower temperatures.

Magnetic studies on Layered solid solution Lix(Ni0.4Mn0.6)2-xO2

International Nuclear Information System (INIS)

Nakao, K; Nakamura, T; Yamada, Y; Koshiba, N

2011-01-01

Li x (Ni 0.4 Mn 0.6 ) 2-x O 2 (1.09≤x≤1.23) were prepared by the solid-state reaction using LiOH and coprecipitated mixed hydroxide as raw materials. All the compounds have a layered rock-salt structure, and the cation mixing degree (Ni 2+ occupancy in the Li-layer) decreases with an increase in x. From the low-temperature magnetic measurement, they all have negative Weiss temperature and spontaneous magnetization, that is, they are ferromagnetic materials. Both the Curie temperature and the spontaneous magnetization at 4.2K decrease with an increase in x. These magnetic variations are attributed to the lowering of the cation mixing degree: the magnetic interaction network turns to two-dimensional one with the loss of the inert-layer coupling. These situations may be considered semi-quantitatively using the ferromagnetic cluster model. Additionally, the cation mixing degree has an influence on their electrochemical properties such as cycle fading and rate capability.

(4-Chloroacetanilido-κ2N,Obis[2-(pyridin-2-ylphenyl-κ2C1,N]iridium(III

Directory of Open Access Journals (Sweden)

Lijun Sun

2013-02-01

Full Text Available In the neutral mononuclear iridium(III title compound, [Ir(C8H7ClNO(C11H8N2], the IrIII atom adopts an octahedral geometry, and is coordinated by two 2-phenylpyridyl ligands and one anionic 4-chloroacetanilide ligand. The 2-phenylpyridyl ligands are arranged in a cis-C,C′ and cis-N,N′ fashion. Each 2-phenylpyridyl ligand forms a five-membered ring with the IrIII atom. The 2-phenylpyridyl planes are perpendicular to each other [dihedral angle = 89.9 (1°]. The Ir—C and Ir—N bond lengths are comparable to those reported for related iridium(III 2-phenylpyridyl complexes. The remaining two coordination sites are occupied by the amidate N and O atoms, which form a four-membered ring with the iridium atom (Ir—N—C—O. The amidate plane is nearly perpendicular to both 2-phenylpyridyl ligands [dihedral angles = 87.8 (2 and 88.3 (2°].

Topologically identical, but geometrically isomeric layers in hydrous α-, β-Rb[UO2(AsO3OH)(AsO2(OH)2)]·H2O and anhydrous Rb[UO2(AsO3OH)(AsO2(OH)2)

International Nuclear Information System (INIS)

Yu, Na; Klepov, Vladislav V.; Villa, Eric M.; Bosbach, Dirk; Suleimanov, Evgeny V.; Depmeier, Wulf; Albrecht-Schmitt, Thomas E.; Alekseev, Evgeny V.

2014-01-01

The hydrothermal reaction of uranyl nitrate with rubidium nitrate and arsenic (III) oxide results in the formation of polymorphic α- and β-Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )]·H 2 O (α-, β-RbUAs) and the anhydrous phase Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )] (RbUAs). These phases were structurally, chemically and spectroscopically characterized. The structures of all three compounds are based upon topologically identical, but geometrically isomeric layers. The layers are linked with each other by means of the Rb cations and hydrogen bonding. Dehydration experiments demonstrate that water deintercalation from hydrous α- and β-RbUAs yields anhydrous RbUAs via topotactic reactions. - Graphical abstract: Three different layer geometries observed in the structures of Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )] and α- and β- Rb[UO 2 (AsO 3 OH)(AsO 2 (OH) 2 )]·H 2 O. Two different coordination environments of uranium polyhedra (types I and II) are shown schematically on the top of the figure. - Highlights: • Three new uranyl arsenates were synthesized from the hydrothermal reactions. • The phases consist of the topologically identical but geometrically different layers. • Topotactic transitions were observed in the processes of mono-hyrates dehydration

K2Ln2As2Se9 (Ln = Sm, Gd): the first quaternary rare-earth selenoarsenate compounds with a 3D framework containing chairlike As2Se4 units.

Science.gov (United States)

Wu, Yuandong; Bensch, Wolfgang

2009-04-06

The new compounds K(2)Ln(2)As(2)Se(9) (Ln = Sm, Gd) were obtained by applying the reactive flux method. The structure consists of a three-dimensional (3D) [Ln(2)As(2)Se(9)](2-) framework with K(+) ion-filling tunnels running along the b axis. The two unique Ln(3+) cations are coordinated by two Se(2)(2-) dumbbells, two AsSe(3)(3-) pyramids, and one chairlike As(2)Se(4)(2-) unit in a bicapped trigonal-prismatic geometry. The Ln(3+)-centered trigonal prisms share triangular faces with neighboring prisms, forming one-dimensional chains along the b axis. These chains are linked to each other to form layers by sharing Se(2-) anions on the capped sites of the trigonal prisms. The As(2)Se(4) units connect these layers to form the 3D framework.

Synthesis of [PtCl2(4,4′-dialkoxy-2,2′-bipyridine)] complexes and their in vitro anticancer properties

Science.gov (United States)

Vo, Van; Tanthmanatham, Ontida; Han, Haesook; Bhowmik, Pradip K.; Spangelo, Bryan L.

2013-01-01

A series of [Pt(II)Cl2(4,4′-dialkoxy-2,2′-bipyridine)] complexes of the general formula of[Pt(II)Cl2(4,4′-bis(RO)-2,2′-bipyridine)] (where R = −(CH2)n−1CH3, n = 2–6,8) were synthesized and characterized using 1H NMR, 13C NMR spectroscopy, elemental analysis, mass spectroscopy, and differential scanning calorimetry measurements. The in vitro anti-proliferative activities of these compounds were evaluated against human cancer cell lines A549 (lung adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), and MDA-MB-435 (melanoma) using the MTS cell proliferation assay. Several Pt(II) coordination compounds were found to have greatly enhanced activity compared to cisplatin after a one hour treatment in all cell lines tested. A structure-activity relationship was observed, that is, the activity increases as the carbon chain length of the alkyl group increases. The activity was maximum when the carbon chain length reaches four or five carbons and decreased with the longer carbon chain length. Fluorescence microscopy and flow cytometry data indicate that the main mode of cell death is through apoptosis with some necrotic responses. PMID:23817622

Long-term corrosion tests of Ti{sub 3}SiC{sub 2} and Ti{sub 2}AlC in oxygen containing LBE at temperatures up to 700 °C

Energy Technology Data Exchange (ETDEWEB)

Heinzel, A., E-mail: Annette.heinzel@kit.edu; Weisenburger, A.; Müller, G.

2016-12-15

Two MAX-phase materials, Ti{sub 3}SiC and Ti{sub 2}AlC, were tested at 550 °C, 650 °C and 700 °C up to 10 000 h in LBE (lead-bismuth-eutectic) containing of 10{sup −6} and 10{sup −8} wt% oxygen. It was found that secondary phases have a strong influence on corrosion effects. Ti{sub 3}SiC showed a surface disintegration at 550°C/10{sup −6} wt% oxygen after longer exposure, while a 4–7 μm thick TiO{sub 2} layer with Pb-Bi inclusions was detected on Ti{sub 2}AlC. However, Ti{sub 3}SiC is protected by a double layered oxide with an outer part of TiO{sub 2} and a mixed inner layer of SiO{sub 2} and TiO{sub 2} at the higher temperatures. Ti{sub 2}AlC formed a TiO{sub 2} surface layer containing Al{sub 2}O{sub 3}. Some defects could be observed on the Ti{sub 3}SiC surface in LBE containing 10{sup −8} wt% oxygen at 550 °C and 650 °C. The secondary phases between the Ti{sub 3}SiC grains showed strong oxidation at 700 °C. Due to the high Al solubility in LBE, Ti{sub 2}AlC experienced strong dissolution attack after longer exposure times at 650 and 700 °C.

Structure-Activity Relationships of Truncated C2- or C8-Substituted Adenosine Derivatives as Dual Acting A2A and A3 Adenosine Receptor Ligands

Science.gov (United States)

Hou, Xiyan; Majik, Mahesh S.; Kim, Kyunglim; Pyee, Yuna; Lee, Yoonji; Alexander, Varughese; Chung, Hwa-Jin; Lee, Hyuk Woo; Chandra, Girish; Lee, Jin Hee; Park, Seul-gi; Choi, Won Jun; Kim, Hea Ok; Phan, Khai; Gao, Zhan-Guo; Jacobson, Kenneth A.; Choi, Sun; Lee, Sang Kook; Jeong, Lak Shin

2011-01-01

Truncated N6-substituted-4′-oxo- and 4′-thioadenosine derivatives with C2 or C8 substitution were studied as dual acting A2A and A3 adenosine receptor (AR) ligands. The lithiation-mediated stannyl transfer and palladium-catalyzed cross coupling reactions were utilized for functionalization of the C2 position of 6-chloropurine nucleosides. An unsubstituted 6-amino group and a hydrophobic C2 substituent were required for high affinity at the hA2AAR, but hydrophobic C8 substitution abolished binding at the hA2AAR. However, most of synthesized compounds displayed medium to high binding affinity at the hA3AR, regardless of C2 or C8 substitution, and low efficacy in a functional cAMP assay. Several compounds tended to be full hA2AAR agonists. C2 substitution probed geometrically through hA2AAR-docking, was important for binding in order of hexynyl > hexenyl > hexanyl. Compound 4g was the most potent ligand acting dually as hA2AAR agonist and hA3AR antagonist, which might be useful for treatment of asthma or other inflammatory diseases. PMID:22142423

Temperature stability of c-axis oriented LiNbO{sub 3}/SiO{sub 2}/Si thin film layered structures

Energy Technology Data Exchange (ETDEWEB)

Tomar, Monika [Department of Physics and Astrophysics, University of Delhi, Delhi (India)]. E-mail: mtomar@physics.du.ac.in; monikatomar@rediffmail.com; Gupta, Vinay; Mansingh, Abhai; Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, Delhi (India)

2001-08-07

Theoretical calculations have been performed for the temperature stability of the c-axis oriented LiNbO{sub 3} thin film layered structures on passivated silicon (SiO{sub 2}/Si) substrate with and without a non-piezoelectric SiO{sub 2} overlayer. The phase velocity, electromechanical coupling coefficient and temperature coefficient of delay (TCD) have been calculated. The thicknesses of various layers have been determined for optimum SAW performance with zero TCD. The presence of a non-piezoelectric SiO{sub 2} overlayer on LiNbO{sub 3} film is found to significantly enhance the coupling coefficient. The optimized results reveal that a high coupling coefficient of K{sup 2}=3.45% and a zero TCD can be obtained in the SiO{sub 2}/LiNbO{sub 3}/SiO{sub 2}/Si structure with a 0.235{lambda} thick LiNbO{sub 3} layer sandwiched between 0.1{lambda} thick SiO{sub 2} layers. (author)

Comment on 'Pressure-induced changes in transport properties of layered La1.2Ca1.8Mn2O7'

International Nuclear Information System (INIS)

Ganguly, R.; Siruguri, V.; Gopalakrishnan, I.K.; Yakhmi, J.V.

2000-01-01

We show that the compound La 1.2 Ca 1.8 Mn 2 O 7 does not form with layered Sr 3 Ti 2 O 7 -type structure as reported by Kamenev et al. [Phys. Rev. B 56, R12 688 (1997)]. Detailed analysis of the powder x-ray diffraction pattern of this compound (synthesized by using the solid-state method) by Rietveld method shows that it forms a multiphase mixture comprising hole-doped perovskite manganates (La 1-x Ca x MnO 3 ) as the majority phases and CaO as the minority phase

3D spin-flop transition in enhanced 2D layered structure single crystalline TlCo2Se2

Science.gov (United States)

Jin, Z.; Xia, Z.-C.; Wei, M.; Yang, J.-H.; Chen, B.; Huang, S.; Shang, C.; Wu, H.; Zhang, X.-X.; Huang, J.-W.; Ouyang, Z.-W.

2016-10-01

The enhanced 2D layered structure single crystalline TlCo2Se2 has been successfully fabricated, which exhibits field-induced 3D spin-flop phase transitions. In the case of the magnetic field parallel to the c-axis (B//c), the applied magnetic field induces the evolution of the noncollinear helical magnetic coupling into a ferromagnetic (FM) state with all the magnetization of the Co ion parallel to the c-axis. A striking variation of the field-induced strain within the ab-plane is noticed in the magnetic field region of 20-30 T. In the case of the magnetic field perpendicular to the c-axis (B  ⊥  c), the inter-layer helical antiferromagnetic (AFM) coupling may transform to an initial canted AFM coupling, and then part of it transforms to an intermediate metamagnetic phase with the alignment of two-up-one-down Co magnetic moments and finally to an ultimate FM coupling in higher magnetic fields. The robust noncollinear AFM magnetic coupling is completely destroyed above 30 T. In combination with the measurements of magnetization, magnetoresistance and field-induced strain, a complete magnetic phase diagram of the TlCo2Se2 single crystal has been depicted, demonstrating complex magnetic structures even though the crystal geometry itself gives no indication of the magnetic frustration.

Synthesis, structure, optical, photoluminescence and magnetic properties of K2[Co(C2O4)2(H2O)2]·4H2O

Science.gov (United States)

Narsimhulu, M.; Hussain, K. A.

2018-06-01

The synthesis, crystal structure, optical, photoluminescence and magnetic behaviour of potassium bis(oxalato)cobaltate(II)tertrahydrate{K2[Co(C2O4)2(H2O)2]·4H2O} are described. The compound was grown at room temperature from mixture of aqueous solutions by slow evaporation method. The X-ray crystallographic data showed that the compound belongs to the monoclinic crystal system with P21/n space group and Z = 4. The UV-visible diffuse absorbance spectra exhibited bands at 253, 285 and 541 nm in the visible and ultraviolet regions. The optical band gap of the compound was estimated as 3.4 eV. At room temperature, an intense photoluminescence was observed from this material around 392 nm when it excited at 254 nm. The variable temperature dc magnetic susceptibility measurements exposed paramagnetic behaviour at high temperatures and antiferromagnetic ordering at low temperatures.

Hydrothermal synthesis, structural elucidation, spectroscopic studies, thermal behavior and luminescence properties of a new 3-d compound: FeAlF2(C10H8N2)(HPO4)2(H2O)

Science.gov (United States)

Bouzidia, Nabaa; Salah, Najet; Hamdi, Besma; Ben Salah, Abdelhamid

2017-04-01

The study of metal phosphate has been a proactive field of research thanks to its applied and scientific importance, especially in terms of the development of optical devices such as solid state lasers as well as optical fibers. The present paper seeks to investigate the synthesis, crystal structure, elemental analysis and properties of FeAlF2(C10H8N2)(HPO4)2(H2O) compound investigated by spectroscopic studies (FT-IR and FT-Raman), thermal behavior and luminescence. The Hirshfeld surface analysis and 2-D fingerprint plot have been performed to explore the behavior of these weak interactions and crystal cohesion. This investigation shows that the molecules are connected by hydrogen bonds of the type Osbnd H⋯O and Osbnd H⋯F. In addition, the 2,2'‒bipyridine ligand plays a significant role in the construction of 3-D supramolecular framework via π‒π stacking. FT‒IR and FT‒Raman spectra were used so as to ease the responsibilities of the vibration modes of the title compound. The thermal analysis (TGA) study shows a mass loss evolution as a temperature function. Finally, the optical properties were evaluated by photoluminescence spectroscopy.

Synthesis and characterization of an energetic compound Cu(Mtta)2(NO3)2 and effect on thermal decomposition of ammonium perchlorate

International Nuclear Information System (INIS)

Yang, Qi; Chen, Sanping; Xie, Gang; Gao, Shengli

2011-01-01

Highlights: ► A new energetic compound Cu(Mtta) 2 (NO 3 ) 2 has been synthesized and structural characterized. ► Sensitivity tests reveal that the compound is insensitive to mechanical stimuli. ► Cu(Mtta) 2 (NO 3 ) 2 accelerates the decomposition of Ammonium perchlorate (AP), which is the key component of composite solid propellant. - Abstract: An energetic coordination compound Cu(Mtta) 2 (NO 3 ) 2 has been synthesized by using 1-methyltetrazole (Mtta) as ligand and its structure has been characterized by X-ray single crystal diffraction. The central copper (II) cation was coordinated by four O atoms from two Mtta ligands and two N atoms from two NO 3 − anions to form a six-coordinated and distorted octahedral structure. 2D superamolecular layer structure was formed by the extensive intermolecular hydrogen bonds between Mtta ligands and NO 3 − anions. Thermal decomposition process of the compound was predicted based on DSC and TG-DTG analyses results. The kinetic parameters of the first exothermic process of the compound were studied by the Kissinger's and Ozawa–Doyle's methods. Sensitivity tests revealed that the compound was insensitive to mechanical stimuli. In addition, compound was explored as additive to promote the thermal decomposition of ammonium perchlorate (AP) by differential scanning calorimetry.

Group IB Organometallic Chemistry XXXIV: Thermal behavior and chemical reactivity of tetranuclear Me2N-substituted diarylpropenylcopper-copper anion (Vi2Cu4X2) and mixed diarylpropenyl/organocopper (Vi2Cu4R2) compounds

NARCIS (Netherlands)

Koten, G. van; Hoedt, R.W.M. ten; Noltes, J.G.

1980-01-01

Thermal decomposition of configurationally pure 1, 2-diarylpropenylcopper compounds Z-Vi{2}CU{4}Br{2} and Z-Vi{2}Cu{4}R{2} [Vi @? (2-Me{2}NC{6}H{4})C@?C(Me)-(C{6}H{4}Me-4), R @? 2-Me{2}NC{6}H{4} or 4-MeC{6}H{4}C@?C] predominantly results in the formation of ViH. In contrast, only dimers (ViVi) were

Direct observation of effective temperature of Ta atom in layer compound TaS2 by neutron resonance absorption spectrometer

International Nuclear Information System (INIS)

Tokuda, Koji; Kamiyama, Takashi; Kiyanagi, Yoshiaki; Moreh, R.; Ikeda, Susumu

2001-01-01

A neutron resonance absorption spectrometer, DOG has been installed at KENS, High Energy Accelerator Research Organization Neutron Source, which enables us to investigate the motions of a particular element by analyzing the line width of resonance absorption spectrum. We measured the temperature dependence of the effective temperature of Ta motion in TaS 2 as well as in Ta metal using DOG. The effective temperatures extracted from the observed absorption spectrum agree well with the calculated values from the phonon density of states of Ta metal over a wide temperature range of 10 to 300 K. We also succeeded in measuring both the angular dependence and the temperature dependence of effective temperatures of Ta in a layer compound TaS 2 . Based on the temperature dependence of the effective temperature, the partial phonon density of states of Ta in TaS 2 was discussed. (author)

Expression of paired-like homeodomain transcription factor 2c (PITX2c) in epidermal keratinocytes

International Nuclear Information System (INIS)

Shi, Ge; Sohn, Kyung-Cheol; Choi, Tae-Young; Choi, Dae-Kyoung; Lee, Sang-Sin; Ou, Bai-sheng; Kim, Sooil; Lee, Young Ho; Yoon, Tae-Jin; Kim, Seong-Jin; Lee, Young; Seo, Young-Joon; Lee, Jeung-Hoon; Kim, Chang Deok

2010-01-01

Paired-like homeodomain transcription factor 2 (PITX2) has been implicated as one of the genes responsible for Rieger syndrome. It has been also shown to play a central role during development. In this study, we investigated the functional role of PITX2 in keratinocyte differentiation. RT-PCR analysis showed that PITX2c isoform was predominantly expressed in a differentiation-dependent manner. Consistent with, immunohistochemical staining showed that PITX2 expression was increased in the upper layer of epidermis. When PITX2c was overexpressed in cultured keratinocytes by a recombinant adenovirus, the differentiation markers such as involucrin and loricrin were significantly increased at both mRNA and protein levels. In addition, PITX2c overexpression led to the decrease of cell growth, concomitantly with the upregulation of cell cycle-related genes p21. To investigate the effect of PITX2c in vivo, we microinjected PITX2c expression vector into zebrafish embryo. Interestingly, overexpression of PITX2c in zebrafish embryo led to the formation of horn-like structure and thickening of epidermis, together with the increase of keratin 8 (K8) expression. These results suggest that PITX2c has a role in proliferation and differentiation of epidermal keratinocytes.

Expression of paired-like homeodomain transcription factor 2c (PITX2c) in epidermal keratinocytes

Energy Technology Data Exchange (ETDEWEB)

Shi, Ge [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Department of Dermatology, The First Affiliated Hospital, Guangxi Traditional Chinese Medical University, Guangxi, Nanning, 530023 (China); Sohn, Kyung-Cheol; Choi, Tae-Young; Choi, Dae-Kyoung; Lee, Sang-Sin [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Ou, Bai-sheng [Department of Dermatology, The First Affiliated Hospital, Guangxi Traditional Chinese Medical University, Guangxi, Nanning, 530023 (China); Kim, Sooil; Lee, Young Ho [Department of Anatomy, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Yoon, Tae-Jin [Department of Dermatology, School of Medicine, Gyeongsang National University, Jinju, 660-702 (Korea, Republic of); Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju, 660-702 (Korea, Republic of); Kim, Seong-Jin [Department of Dermatology, Chonnam National University Medical School, Gwangju, 501-757 (Korea, Republic of); Lee, Young; Seo, Young-Joon; Lee, Jeung-Hoon [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Kim, Chang Deok, E-mail: cdkimd@cnu.ac.kr [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of)

2010-11-15

Paired-like homeodomain transcription factor 2 (PITX2) has been implicated as one of the genes responsible for Rieger syndrome. It has been also shown to play a central role during development. In this study, we investigated the functional role of PITX2 in keratinocyte differentiation. RT-PCR analysis showed that PITX2c isoform was predominantly expressed in a differentiation-dependent manner. Consistent with, immunohistochemical staining showed that PITX2 expression was increased in the upper layer of epidermis. When PITX2c was overexpressed in cultured keratinocytes by a recombinant adenovirus, the differentiation markers such as involucrin and loricrin were significantly increased at both mRNA and protein levels. In addition, PITX2c overexpression led to the decrease of cell growth, concomitantly with the upregulation of cell cycle-related genes p21. To investigate the effect of PITX2c in vivo, we microinjected PITX2c expression vector into zebrafish embryo. Interestingly, overexpression of PITX2c in zebrafish embryo led to the formation of horn-like structure and thickening of epidermis, together with the increase of keratin 8 (K8) expression. These results suggest that PITX2c has a role in proliferation and differentiation of epidermal keratinocytes.

Stability Criteria of Fullerene-like Nanoparticles: Comparing V2O5 to Layered Metal Dichalcogenides and Dihalides

Directory of Open Access Journals (Sweden)

Yehiam Prior

2010-08-01

Full Text Available Numerous examples of closed-cage nanostructures, such as nested fullerene-like nanoparticles and nanotubes, formed by the folding of materials with layered structure are known. These compounds include WS2, NiCl2, CdCl2, Cs2O, and recently V2O5. Layered materials, whose chemical bonds are highly ionic in character, possess relatively stiff layers, which cannot be evenly folded. Thus, stress-relief generally results in faceted nanostructures seamed by edge-defects. V2O5, is a metal oxide compound with a layered structure. The study of the seams in nearly perfect inorganic "fullerene-like" hollow V2O5 nanoparticles (NIF-V2O5 synthesized by pulsed laser ablation (PLA, is discussed in the present work. The relation between the formation mechanism and the seams between facets is examined. The formation mechanism of the NIF-V2O5 is discussed in comparison to fullerene-like structures of other layered materials, like IF structures of MoS2, CdCl2, and Cs2O. The criteria for the perfect seaming of such hollow closed structures are highlighted.

Synthesis, characterization, electrochemical investigation and antioxidant activities of a new hybrid cyclohexaphosphate: Cu1.5Li(C2H10N2)P6O18·7H2O

Science.gov (United States)

Sleymi, Samira; Lahbib, Karima; Rahmouni, Nihed; Rzaigui, Mohamed; Besbes-Hentati, Salma; Abid, Sonia

2017-09-01

A new organic-inorganic hybrid transition metal phosphate, Cu1.5Li(C2H10N2)P6O18·7H2O, has been prepared and characterized by X-ray diffraction, spectroscopy (infrared, Raman, diffuse reflectance and UV-Vis) and thermal analysis (TG). In addition, its electrochemical behaviors, as well as its antioxidant and antibacterial activities, have been investigated. Its structure is built up by the alternate linkages between copper and phosphate polyhedra, forming puckered layers with intersecting 12-membered rings, in which the ethylenediammonium cations reside. This compound is the first framework structure constructed from cyclohexaphosphates and three distinct copper cations. Cyclic voltammetry study in an acetonitrile solution reveals the facile anodic oxidation of its organic part on a platinum disk and a progressive growing of a thin film, though the repetitive cycling of potential. The title compound was tested for its in vitro antioxidant activities by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), Ferrous chelating ability (FIC) and Ferric Reducing Power (FRP) methods. The antioxidant activity of Cu1.5Li(C2H10N2)P6O18·7H2O was analyzed simultaneously with its antibacterial capacity against Escherichia coli, Salmonella typhimurium, Staphylococus aureus, Enterococcus feacium, Streptococcus agalactiae and Candida albicans. The tested compound showed significant antioxidant activities with low antibacterial properties.

Synthesis and crystal structures of new complexes of Np(V) glycolate with 2,2'-bipyridine, [NpO2(C10H8N2)(OOC2H2OH)].1.5H2O and [NpO2(C10H8N2)(OOC2H2OH)].2.5H2O

International Nuclear Information System (INIS)

Charushnikova, I.A.; Krot, N.N.; Starikova, Z.A.

2009-01-01

Single crystals were prepared, and the structures of two complexes of Np(V) glycolate with 2,2'-bipyridine of the compositions [NpO 2 (C 10 H 8 N 2 )(OOC 2 H 2 OH)].1.5H 2 O (I) and [NpO 2 (C 10 H 8 N 2 )(OOC 2 H 2 OH)]2.5H 2 O (II) were studied. The structures of the compounds are based on neptunyl-glycolate chains in which the glycolate anion manifests its complexation ability in different manner. In structure I, the bidentate-bridging anion links the adjacent NpO 2 - cations through the oxygen atoms of the carboxylate group. The neptunyl-glycolate chains of I exhibits the mutual coordination of the NpO 2 - cations acting toward each other simultaneously as ligands and coordinating centers. In compound II, the glycolate anion is bidentately coordinated to one neptunium atom to form a planar five-membered metallocycle [NpOCCO]. The O atom external with respect to the metallocycle is in the coordination environment of the adjacent neptunyl. The nitrogen-containing molecular ligand Bipy is included into the coordination environment of Np. The coordination polyhedron of the Np atoms in both structures is a pentagonal bipyramid in which the average Np-N bond length is 2.666 Aa (I) and 2.596 Aa (II). (orig.)

Crystal structures of N-(4-chlorophenyl-2-[(4,6-diaminopyrimidin-2-ylsulfanyl]acetamide and N-(3-chlorophenyl-2-[(4,6-diaminopyrimidin-2-ylsulfanyl]acetamide

Directory of Open Access Journals (Sweden)

S. Subasri

2017-04-01

Full Text Available The title compounds, C12H12ClN5OS, (I, and C12H12ClN5OS, (II, are 2-[(diaminopyrimidin-2-ylsulfanyl]acetamides. Compound (II, crystallizes with two independent molecules (A and B in the asymmetric unit. In each of the molecules, in both (I and (II, an intramolecular N—H...N hydrogen bond forms an S(7 ring motif. The pyrimidine ring is inclined to the benzene ring by 42.25 (14° in (I, and by 59.70 (16 and 62.18 (15° in molecules A and B, respectively, of compound (II. In the crystal of (I, molecules are linked by pairs of N—H...N hydrogen bonds, forming inversion dimers with an R22(8 ring motif. The dimers are linked via bifurcated N—H...O and C—H...O hydrogen bonds, forming corrugated layers parallel to the ac plane. In the crystal of (II, the A molecules are linked through N—H...O and N—H...Cl hydrogen bonds, forming layers parallel to (100. The B molecules are also linked by N—H...O and N—H...Cl hydrogen bonds, also forming layers parallel to (100. The parallel layers of A and B molecules are linked via N—H...N hydrogen bonds, forming a three-dimensional structure.

Vortex lattice structures in YNi2B2C

International Nuclear Information System (INIS)

Yethiraj, M.; Paul, D.M.; Tomy, C.V.; Forgan, E.M.

1997-01-01

The authors observe a flux lattice with square symmetry in the superconductor YNi 2 B 2 C when the applied field is parallel to the c-axis of the crystal. A square lattice observed previously in the isostructural magnetic analog ErNi 2 B 2 C was attributed to the interaction between magnetic order in that system and the flux lattice. Since the Y-based compound does not order magnetically, it is clear that the structure of the flux lattice is unrelated to magnetic order. In fact, they show that the flux lines have a square cross-section when the applied field is parallel to the c-axis of the crystal, since the measured penetration depth along the 100 crystal direction is larger than the penetration depth along the 110 by approximately 60%. This is the likely reason for the square symmetry of the lattice. Although they find considerable disorder in the arrangement of the flux lines at 2.5T, no melting of the vortex lattice was observed

Solution-Processed Ultrathin TiO2 Compact Layer Hybridized with Mesoporous TiO2 for High-Performance Perovskite Solar Cells.

Science.gov (United States)

Jeong, Inyoung; Park, Yun Hee; Bae, Seunghwan; Park, Minwoo; Jeong, Hansol; Lee, Phillip; Ko, Min Jae

2017-10-25

The electron transport layer (ETL) is a key component of perovskite solar cells (PSCs) and must provide efficient electron extraction and collection while minimizing the charge recombination at interfaces in order to ensure high performance. Conventional bilayered TiO 2 ETLs fabricated by depositing compact TiO 2 (c-TiO 2 ) and mesoporous TiO 2 (mp-TiO 2 ) in sequence exhibit resistive losses due to the contact resistance at the c-TiO 2 /mp-TiO 2 interface and the series resistance arising from the intrinsically low conductivity of TiO 2 . Herein, to minimize such resistive losses, we developed a novel ETL consisting of an ultrathin c-TiO 2 layer hybridized with mp-TiO 2 , which is fabricated by performing one-step spin-coating of a mp-TiO 2 solution containing a small amount of titanium diisopropoxide bis(acetylacetonate) (TAA). By using electron microscopies and elemental mapping analysis, we establish that the optimal concentration of TAA produces an ultrathin blocking layer with a thickness of ∼3 nm and ensures that the mp-TiO 2 layer has a suitable porosity for efficient perovskite infiltration. We compare PSCs based on mesoscopic ETLs with and without compact layers to determine the role of the hole-blocking layer in their performances. The hybrid ETLs exhibit enhanced electron extraction and reduced charge recombination, resulting in better photovoltaic performances and reduced hysteresis of PSCs compared to those with conventional bilayered ETLs.

Similar substrate specificity of cynomolgus monkey cytochrome P450 2C19 to reported human P450 2C counterpart enzymes by evaluation of 89 drug clearances.

Science.gov (United States)

Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

2015-12-01

Cynomolgus monkeys are used widely in preclinical studies as non-human primate species. The amino acid sequence of cynomolgus monkey cytochrome P450 (P450 or CYP) 2C19 is reportedly highly correlated to that of human CYP2C19 (92%) and CYP2C9 (93%). In the present study, 89 commercially available compounds were screened to find potential substrates for cynomolgus monkey CYP2C19. Of 89 drugs, 34 were metabolically depleted by cynomolgus monkey CYP2C19 with relatively high rates. Among them, 30 compounds have been reported as substrates or inhibitors of, either or both, human CYP2C19 and CYP2C9. Several compounds, including loratadine, showed high selectivity to cynomolgus monkey CYP2C19, and all of these have been reported as human CYP2C19 and/or CYP2C9 substrates. In addition, cynomolgus monkey CYP2C19 formed the same loratadine metabolite as human CYP2C19, descarboethoxyloratadine. These results suggest that cynomolgus monkey CYP2C19 is generally similar to human CYP2C19 and CYP2C9 in its substrate recognition functionality. Copyright © 2015 John Wiley & Sons, Ltd.

Synthesis of (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)olivetolic acid, methyl (1'-/sup 13/C)olivetolate and (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)cannabigerolic acid

Energy Technology Data Exchange (ETDEWEB)

Porwoll, J P; Leete, E [Minnesota Univ., Minneapolis (USA). Dept. of Chemistry

1985-03-01

Potential advanced intermediates in the biosynthesis of delta/sup 9/-tetrahydrocannabinol, the major psychoactive principle of marijuana, have been synthesized labeled with two contiguous /sup 13/C atoms and /sup 14/C. Methyl (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)olivetolate was prepared from lithium (/sup 13/C/sub 2/)acetylide and dimethyl (2-/sup 14/C)malonate. Reaction with geranyl bromide afforded methyl (5,6-/sup 13/C/sub 2/, 1-/sup 14/C)cannabigerolate, and hydrolysis of these methyl esters with lithium propyl mercaptide yielded the corresponding labeled acids. The /sup 13/C-/sup 13/C couplings observable in the /sup 13/C NMR spectra of these /sup 13/C-enriched compounds and their synthetic precursors are recorded. Methyl (1'-/sup 14/C)olivetolate was prepared from /sup 13/CO/sub 2/ to confirm assignments of the /sup 13/C chemical shifts in the pentyl side chain of these compounds.

Control of electronic properties of 2D carbides (MXenes) by manipulating their transition metal layers

KAUST Repository

Anasori, Babak

2016-02-24

In this study, a transition from metallic to semiconducting-like behavior has been demonstrated in two-dimensional (2D) transition metal carbides by replacing titanium with molybdenum in the outer transition metal (M) layers of M3C2 and M4C3 MXenes. The MXene structure consists of n + 1 layers of near-close packed M layers with C or N occupying the octahedral site between them in an [MX]nM arrangement. Recently, two new families of ordered 2D double transition metal carbides MXenes were discovered, M′2M′′C2 and M′2M′′2C3 – where M′ and M′′ are two different early transition metals, such as Mo, Cr, Ta, Nb, V, and Ti. The M′ atoms only occupy the outer layers and the M′′ atoms fill the middle layers. In other words, M′ atomic layers sandwich the middle M′′–C layers. Using X-ray atomic pair distribution function (PDF) analysis on Mo2TiC2 and Mo2Ti2C3 MXenes, we present the first quantitative analysis of structures of these novel materials and experimentally confirm that Mo atoms are in the outer layers of the [MC]nM structures. The electronic properties of these Mo-containing MXenes are compared with their Ti3C2 counterparts, and are found to be no longer metallic-like conductors; instead the resistance increases mildly with decreasing temperatures. Density functional theory (DFT) calculations suggest that OH terminated Mo–Ti MXenes are semiconductors with narrow band gaps. Measurements of the temperature dependencies of conductivities and magnetoresistances have confirmed that Mo2TiC2Tx exhibits semiconductor-like transport behavior, while Ti3C2Tx is a metal. This finding opens new avenues for the control of the electronic and optical applications of MXenes and for exploring new applications, in which semiconducting properties are required.

Layered distributed simulation architecture to support the C2 enterprise

CSIR Research Space (South Africa)

Duvenhage, A

2009-09-01

Full Text Available between these systems and that a capability is required to demonstrate, support and evaluate interoperability. This paper discusses the layered software architecture of a C++ software application framework for developing applications that support...

High-pressure X-ray diffraction, Raman, and computational studies of MgCl2 up to 1 Mbar: Extensive pressure stability of the β-MgCl2 layered structure.

Science.gov (United States)

Stavrou, Elissaios; Yao, Yansun; Zaug, Joseph M; Bastea, Sorin; Kalkan, Bora; Konôpková, Zuzana; Kunz, Martin

2016-08-12

Magnesium chloride (MgCl2) with the rhombohedral layered CdCl2-type structure (α-MgCl2) has been studied experimentally using synchrotron angle-dispersive powder x-ray diffraction and Raman spectroscopy using a diamond-anvil cell up to 100 GPa at room temperature and theoretically using first-principles density functional calculations. The results reveal a pressure-induced second-order structural phase transition to a hexagonal layered CdI2-type structure (β-MgCl2) at 0.7 GPa: the stacking sequence of the Cl anions are altered resulting in a reduction of the c-axis length. Theoretical calculations confirm this phase transition sequence and the calculated transition pressure is in excellent agreement with the experiment. Lattice dynamics calculations also reproduce the experimental Raman spectra measured for the ambient and high-pressure phase. According to our experimental results MgCl2 remains in a 2D layered phase up to 100 GPa and further, the 6-fold coordination of Mg cations is retained. Theoretical calculations of relative enthalpy suggest that this extensive pressure stability is due to a low enthalpy of the layered structure ruling out kinetic barrier effects. This observation is unusual, as it contradicts with the general structural behavior of highly compressed AB2 compounds.

Et2NH2C6H3(CO23SnBr2.4H2O: SYNTHESIS AND INFRARED STUDY

Directory of Open Access Journals (Sweden)

DAOUDA NDOYE

2014-01-01

Full Text Available The title compound has been obtained on allowing [C6H3(CO23(Et2NH23] to react with SnBr4. The molecular structure of Et2NH2C6H3(CO23SnBr2.4H2O has been determined on the basis of the infrared data. The suggested structure is a dimer in which each tin atom is hexacoordinated by two chelating C6H3(CO233- anions and two Br atoms. Cy2NH2+cations are involved through hydrogen bonds with non-coordinating CO2 groups. The suggested structure is a cage.

Atomic layer deposition of W - based layers on SiO2

NARCIS (Netherlands)

van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; Holleman, J.; Wolters, Robertus A.M.; Aarnink, Antonius A.I.

2003-01-01

W and W1-xNx , where x= 15- 22 at%, thin films were grown using the ALD (Atomic Layer Deposition) principle. Growth rate of W films is about 4- 5 monolayers/ cycle at 300- 350 ºC. Growth rate of W1-xNx is 0.5 monolayer/cycle at 325- 350 ºC. Standard Deviation (STDV) of thickness is about 2%

Enthalpies of formation of layered LiNixMnxCo1-2xO2 (0 ≤ x ≤ 0.5) compounds as lithium ion battery cathode materials

International Nuclear Information System (INIS)

Masoumi, Maryam; Cupid, Damian M.; Reichmann, Thomas L.; Seifert, Hans J.; Chang, Keke; Music, Denis; Schneider, Jochen M.

2017-01-01

Layer-structured mixed transition metal oxides with the formula LiNi x Mn x Co 1-2x O 2 (0 ≤ x ≤ 0.5) are considered as important cathode materials for lithium-ion batteries. In an effort to evaluate the relative thermodynamic stabilities of individual compositions in this series, the enthalpies of formation of selected stoichiometries are determined by high temperature oxide melt drop solution calorimetry and verified by ab-initio calculations. The measured and calculated data are in good agreement with each other, and the results show that LiCoO 2 -LiNi 0.5 Mn 0.5 O 2 solid solution approaches ideal behavior. By increasing x, i.e. by equimolar substitution of Mn 4+ and Ni 2+ for Co 3+ , the enthalpy of formation of LiNi x Mn x Co 1-2x O 2 from the elements becomes more exothermic, implying increased energetic stability. This conclusion is in agreement with the literature results showing improved structural stability and cycling performance of Ni/Mn-rich LiNi x Mn x Co 1-2x O 2 compounds cycled to higher cut-off voltages.

Vacancies and electron localization in the incommensurate intergrowth compound (La0.95Se)(1.21)VSe2

NARCIS (Netherlands)

Ren, Y; Baas, J.; Meetsma, A.; deBoer, J.L.; Wiegers, G.A

1996-01-01

The structure of the inorganic misfit layer compound (La0.95Se)(1.21)VSe2 has been determined on the basis of a four-dimensional superspace group. The crystal is composed of an alternate stacking of VSe2 sandwiches and two-atom-thick LaSe layers. The first subsystem VSe2 has a distorted CdI2-type

Design and Synthesis of 11C-Labelled Compound Libraries for the Molecular Imaging of EGFr, VEGFr-2, AT1 and AT2 Receptors: Transition-Metal Mediated Carbonylations Using [11C]Carbon Monoxide

International Nuclear Information System (INIS)

Aaberg, Ola

2009-01-01

This work deals with radiochemistry and new approaches to develop novel PET tracers labelled with the radionuclide 11 C. Two methods for the synthesis of 11 C-labelled acrylamides have been explored. First, [1- 11 C]-acrylic acid was obtained from a palladium(0)-mediated 11 C-carboxylation of acetylene with [ 11 C]carbon monoxide; this could be converted to the corresponding acyl chloride and then combined with benzylamine to form N-benzyl[carbonyl- 11 C]acrylamide. In the second method, the palladium(0)-mediated carbonylation of vinyl halides with [ 11 C]carbon monoxide was explored. This latter method, yielded labelled acrylamides in a single step with retention of configuration at the C=C double bond, and required less amine compared to the acetylene method. The vinyl halide method was used to synthesize a library of 11 C-labelled EGFr-inhibitors in 7-61% decay corrected radiochemical yield via a combinatorial approach. The compounds were designed to target either the active or the inactive form of EGFr, following computational docking studies. The rhodium(I)-mediated carbonylative cross-coupling of an azide and an amine was shown to be a very general reaction and was used to synthesize a library of dual VEGFr-2/PDGFrβ inhibitors that were 11 C-labelled at the urea position in 38-78% dc rcy. The angiotensin II AT 1 receptor antagonist eprosartan was 11 C-labelled at one of the carboxyl groups in one step using a palladium(0)-mediated carboxylation. Autoradiography shows specific binding in rat kidney, lung and adrenal cortex, and organ distribution shows a high accumulation in the intestines, kidneys and liver. Specific binding in frozen sections of human adrenal incidentalomas warrants further investigations of this tracer. Three angiotensin II AT 2 ligands were 11 C-labelled at the amide group in a palladium(0)-mediated aminocarbonylation in 16-36% dc rcy. One of the compounds was evaluated using in vitro using autoradiography, and in vivo using organ

Bis{2-hydroxyimino-N′-[1-(2-pyridylethylidene]propanohydrazidato}zinc(II dihydrate

Directory of Open Access Journals (Sweden)

Yurii S. Moroz

2010-02-01

Full Text Available The title compound, [Zn(C10H11N4O22]·2H2O, was prepared by the reaction between Zn(CH3COO2·2H2O and 2-hydroxyimino-N′-[1-(2-pyridylethylidene]propanohydrazide (Hpop. The central ZnII atom has a distorted tetragonal-bipyramidal coordination geometry formed by two amide O atoms and four N atoms of two azomethine and two pyridine groups. In the crystal, complex molecules form layers parallel to the crystallographic b direction. The layers are connected by O—H...N and O—H...O hydrogen bonds involving the solvent water molecules.