Isolation of a new two-dimensional honeycomb carbonato-bridged copper(II) complex exhibiting long-range ferromagnetic ordering.

Science.gov (United States)

Majumder, Arpi; Choudhury, Chirantan Roy; Mitra, Samiran; Rosair, Georgina M; El Fallah, M Salah; Ribas, Joan

2005-04-28

Atmospheric CO2 fixation by an aqueous solution containing Cu(ClO4)2.6H2O and 4-aminopyridine (4-apy) yields a novel example of a two-dimensional mu3-CO3 bridged copper(II) complex {[Cu(4-apy)2]3(mu3-CO3)2(ClO4)2.(1/2)CH3OH}n that has been characterized by IR, UV and X-ray crystallography; preliminary magnetic measurements show that complex exhibits long-range ordered ferromagnetic coupling.

Ligand-bridged dinuclear cyclometalated Ir(III) complexes: from metallamacrocycles to discrete dimers.

Science.gov (United States)

Chandrasekhar, Vadapalli; Hajra, Tanima; Bera, Jitendra K; Rahaman, S M Wahidur; Satumtira, Nisa; Elbjeirami, Oussama; Omary, Mohammad A

2012-02-06

Metallamacrocycles 1, 2, and 3 of the general formula [{Ir(ppy)(2)}(2)(μ-BL)(2)](OTf)(2) (ppyH = 2-phenyl pyridine; BL = 1,2-bis(4-pyridyl)ethane (bpa) (1), 1,3-bis(4-pyridyl)propane (bpp) (2), and trans-1,2-bis(4-pyridyl)ethylene (bpe) (3)) have been synthesized by the reaction of [{(ppy)(2)Ir}(2)(μ-Cl)(2)], first with AgOTf to effect dechlorination and later with various bridging ligands. Open-frame dimers [{Ir(ppy)(2)}(2)(μ-BL)](OTf)(2) were obtained in a similar manner by utilizing N,N'-bis(2-pyridyl)methylene-hydrazine (abp) and N,N'-(bis(2-pyridyl)formylidene)ethane-1,2-diamine (bpfd) (for compounds 4 and 5, respectively) as bridging ligands. Molecular structures of 1, 3, 4, and 5 were established by X-ray crystallography. Cyclic voltammetry experiments reveal weakly interacting "Ir(ppy)(2)" units bridged by ethylene-linked bpe ligand in 3; on the contrary the metal centers are electronically isolated in 1 and 2 where the bridging ligands are based on ethane and propane linkers. The dimer 4 exhibits two accessible reversible reduction couples separated by 570 mV indicating the stability of the one-electron reduced species located on the diimine-based bridge abp. The "Ir(ppy)(2)" units in compound 5 are noninteracting as the electronic conduit is truncated by the ethane spacer in the bpfd bridge. The dinuclear compounds 1-5 show ligand centered (LC) transitions involving ppy ligands and mixed metal to ligand/ligand to ligand charge transfer (MLCT/LLCT) transitions involving both the cyclometalating ppy and bridging ligands (BL) in the UV-vis spectra. For the conjugated bridge bpe in compound 3 and abp in compound 4, the lowest-energy charge-transfer absorptions are red-shifted with enhanced intensity. In accordance with their similar electronic structures, compounds 1 and 2 exhibit identical emissions. The presence of vibronic structures in these compounds indicates a predominantly (3)LC excited states. On the contrary, broad and unstructured

Dinuclear ditertiary phosphite derivatives of rhodium

International Nuclear Information System (INIS)

Meintjies, E.

1981-08-01

The overall objective of the research described in this thesis was the design, synthesis, characterization and chemistry of dinuclear complexes of rhodium in which the metal atoms are held in close proximity to each other. Complexes of this nature are of considerable interest owing, in part, to their potential as models for multicentred metal catalysts, as well as to the highly novel and unusual chemistry already discovered for a number of them. A survey of dinuclear complexes of rhodium containing carbonyl and group V donor ligands has been presented as a background introduction to the research reported in this thesis. The coordination behaviour of the diphosphazane ligands, (RO) 2 PN(R')P(OR) 2 (R=Ph or Me, R' = Et; R = Et or Pr/i, R' = Me), and the ditertiary phosphite ligand, (EtO) 2 POP(OEt) 2 , towards certain rhodium precursors has been investigated. A number of highly unusual neutral dinuclear complexes of rhodium, in which these ligands bridge-bond the two rhodium atoms, have been synthesized. Two types of monocarbonyl decarbonylation products are observed for compounds of the type, [Rh 2 Cl 2 (CO) 2 (μ-diphosphazane) 2 ]. 1 H and 31 P[ 1 H] n.m.r. spectral studies have been carried out with the object of establishing the nature of the bridging halogen ligands in the tricarbonyl species. Asymetric zerovalent dinuclear species of the type, [Rh 2 (CO) 3 -[μ-(RO) 2 PN(R')P(OR) 2 ] 2 ] (R = Ph or Me, R' = Et; R = Pr/i, R' = Me), are obtained. A single crystal X-ray analysis has been carried out. Homoleptic cationic species are obtained by reaction of the alkoxydiphosphazane ligands with [Rh(C 8 H 12 )(solvent)(n)] + under the appropriate reaction conditions. The solution and solid-state infrared spectra and the 31 P[ 1 H] n.m.r. spectra of all new compounds synthesized in this study are discussed in terms of possible structures for these compounds. Where appropriate, the n.m.r. spectral data are also discussed in terms of fluxional behaviour

Chlorodiethylaluminum supported on silica: A dinuclear aluminum surface species with bridging μ2-Cl-ligand as a highly efficient co-catalyst for the Ni-catalyzed dimerization of ethene

KAUST Repository

Kermagoret, Anthony; Kerber, Rachel Nathaniel; Conley, Matthew P.; Callens, Emmanuel; Florian, Pierre; Massiot, Dominique; Delbecq, Franç oise; Rozanska, Xavier; Copé ret, Christophe; Sautet, Philippe

2014-01-01

-grafted structures was possible by comparison of the experimental NMR signatures with these calculated by DFT on a wide range of models for the aluminum species (mono- versus di-nuclear, mono- versus bis-grafted with bridging Cl or ethyl). Most of the sites were

Three phenoxo-bridged dinuclear lanthanide complexes. Syntheses, crystal structures, and magnetic properties

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhi-Chao; Dai, Rui-Peng; Yang, En-Cui [College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Tianjin Normal University (China); Dong, Hui-Ming; Zhao, Xiao-Jun [College of Chemistry, Key Laboratory of Inorganic-Organic Hybrid Functional Material Chemistry, Tianjin Normal University (China); Department of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin (China)

2018-03-15

Three dinuclear lanthanide complexes [Ln{sub 2}(H{sub 2}L){sub 2}(NO{sub 3}){sub 4}] [Ln = Dy (1), Tb (2), and Gd (3)] [H{sub 3}L = 2-hydroxyimino-N'-[(2-hydroxy-3-methoxyphenyl)methylidene]- propanohydrazone] were solvothermally synthesized by varying differently anisotropic rare earth ions. Single-crystal structural analyses demonstrate that all the three complexes are crystallographically isostructural with two centrosymmetric Ln{sup III} ions aggregated by a pair of monodeprotonated H{sub 2}L{sup -} anions. Weak intramolecular antiferromagnetic interactions with different strength were mediated by a pair of phenoxo bridges due to superexchange and/or single-ion anisotropy. Additionally, the Dy{sup III}-based entity shows the strongest anisotropy exhibits field-induced single-molecule magnetic behavior with two thermally activated relaxation processes. In contrast, 3 with isotropic Gd{sup III} ion has a significant cryogenic magnetocaloric effect with the maximum entropy change of 25.7 J.kg{sup -1}.K{sup -1} at 2.0 K and 70.0 kOe. (copyright 2018 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N4-methyl-3-thiosemicarbazone: Crystal structure of a novel sulfur bridged copper(II) box-dimer

Science.gov (United States)

Jayakumar, K.; Sithambaresan, M.; Aiswarya, N.; Kurup, M. R. Prathapachandra

2015-03-01

Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N4-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ = 0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)sbnd I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g|| > g⊥ > 2.0023 and the g values in frozen DMF are consistent with the dx2-y2 ground state. The thermal stabilities of some of the complexes were also determined.

Synthesis and spectral characterization of mono- and binuclear copper(II) complexes derived from 2-benzoylpyridine-N⁴-methyl-3-thiosemicarbazone: crystal structure of a novel sulfur bridged copper(II) box-dimer.

Science.gov (United States)

Jayakumar, K; Sithambaresan, M; Aiswarya, N; Kurup, M R Prathapachandra

2015-03-15

Mononuclear and binuclear copper(II) complexes of 2-benzoylpyridine-N(4)-methyl thiosemicarbazone (HL) were prepared and characterized by a variety of spectroscopic techniques. Structural evidence for the novel sulfur bridged copper(II) iodo binuclear complex is obtained by single crystal X-ray diffraction analysis. The complex [Cu2L2I2], a non-centrosymmetric box dimer, crystallizes in monoclinic C2/c space group and it was found to have distorted square pyramidal geometry (Addison parameter, τ=0.238) with the square basal plane occupied by the thiosemicarbazone moiety and iodine atom whereas the sulfur atom from the other coordinated thiosemicarbazone moiety occupies the apical position. This is the first crystallographically studied system having non-centrosymmetrical entities bridged via thiolate S atoms with Cu(II)I bond. The tridentate thiosemicarbazone coordinates in mono deprotonated thionic tautomeric form in all complexes except in sulfato complex, [Cu(HL)(SO4)]·H2O (1) where it binds to the metal centre in neutral form. The magnetic moment values and the EPR spectral studies reflect the binuclearity of some of the complexes. The spin Hamiltonian and bonding parameters are calculated based on EPR studies. In all the complexes g||>g⊥>2.0023 and the g values in frozen DMF are consistent with the d(x2-y2) ground state. The thermal stabilities of some of the complexes were also determined. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and crystal structures of dinuclear trichloro(tetramethylcyclopentadienyl) titanium complexes

Czech Academy of Sciences Publication Activity Database

Lukešová, Lenka; Gyepes, R.; Varga, V.; Pinkas, Jiří; Horáček, Michal; Kubišta, Jiří; Mach, Karel

2006-01-01

Roč. 71, č. 2 (2006), s. 164-178 ISSN 0010-0765 R&D Projects: GA AV ČR KJB400400602 Institutional research plan: CEZ:AV0Z40400503 Keywords : titanium * dinuclear complexes * half-sandwich titanocene * silicon bridge Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.881, year: 2006

Dinuclear Silver(I) and Copper(II) Complexes of Hexadentate Macrocyclic Ligands Containing p-Xylyl Spacers

DEFF Research Database (Denmark)

McKenzie, Christine J.; Nielsen, Lars Preuss; Søtofte, Inger

1998-01-01

The cyclocondensation of terephthalic aldehyde with N,N-bis(3-aminopropyl)-methylamine in the presence of silver(I) gives the dinuclear tetramine Schiff base macrocyclic complex, [Ag2L1](NO3)2 (L1=7,22-N,N'-dimethyl-3,7,11,18, 22,26-hexaazatricyclo[26.2.21.18.213.16]-tetratricosa-2,11,13,15,1 7...

Comparative analysis of electron-density and electron-localization function for dinuclear manganese complexes with bridging boron- and carbon-centered ligands.

Science.gov (United States)

Götz, Kathrin; Kaupp, Martin; Braunschweig, Holger; Stalke, Dietmar

2009-01-01

Bonding in borylene-, carbene-, and vinylidene-bridged dinuclear manganese complexes [MnCp(CO)(2)](2)X (X = B-tBu, B = NMe(2), CH(2), C=CH(2)) has been compared by analyses based on quantum theory of atoms in molecules (QTAIM), on the electron-localization function (ELF), and by natural-population analyses. All of the density functional theory based analyses agree on the absence of a significant direct Mn-Mn bond in these complexes and confirm a dominance of delocalized bonding via the bridging ligand. Interestingly, however, the topology of both charge density and ELF related to the Mn-bridge-Mn bonding depend qualitatively on the chosen density functional (except for the methylene-bridged complex, which exhibits only one three-center-bonding attractor both in -nabla(2)rho and in ELF). While gradient-corrected functionals provide a picture with localized two-center X-Mn bonding, increasing exact-exchange admixture in hybrid functionals concentrates charge below the bridging atom and suggests a three-center bonding situation. For example, the bridging boron ligands may be described either as substituted boranes (e.g., at BLYP or BP86 levels) or as true bridging borylenes (e.g., at BHLYP level). This dependence on the theoretical level appears to derive from a bifurcation between two different bonding situations and is discussed in terms of charge transfer between X and Mn, and in the context of self-interaction errors exhibited by popular functionals.

Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, 57Fe Moessbauer spectroscopy and thermal studies

International Nuclear Information System (INIS)

Travnicek, Zdenek; Herchel, Radovan; Mikulik, Jiri; Zboril, Radek

2010-01-01

Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN) 5 NO].H 2 O (1), where tet=N,N'-bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN) 5 NO].2H 2 O (2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9 ]octadecane and [Cu(nme) 2 Fe(CN) 5 NO].H 2 O (3), where nme=N-methylethylenediamine, were synthesized and characterized by elemental analyses, 57 Fe Moessbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, 57 Fe Moessbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe 2 O 4 and CuO. - Three heterobimetallic cyano-bridged copper(II) nitroprusside-based complexes of the general compositions of [Cu(L)Fe(CN) 5 NO].xH 2 O, where L=N,N'-bis(3-aminopropyl)ethylenediamine (complex 1), 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9 ]-octadecane (complex 2) and N-methylethylenediamine (complex 3), were synthesized, and fully structurally and magnetically characterized. SEM, EDS, XRD and 57 Fe Moessbauer experiments were used for characterization of thermal decomposition products of complexes 2 and 3.

Self assembly of dialkoxo bridged dinuclear Fe(III) complex of pyridoxal Schiff base with C-C bond formation - structure, spectral and magnetic properties

Czech Academy of Sciences Publication Activity Database

Murašková, V.; Szabó, N.; Pižl, M.; Hoskovcová, I.; Dušek, Michal; Huber, Š.; Sedmidubský, D.

2017-01-01

Roč. 461, May (2017), s. 111-119 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GA15-12653S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : iron(III) dinuclear complex * dialkoxo bridged pyridoxal Schiff base * C-C bond * crystal structure * magnetic properties Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.002, year: 2016

Tetranuclear copper(II) complexes bridged by alpha-D-glucose-1-phosphate and incorporation of sugar acids through the Cu4 core structural changes.

Science.gov (United States)

Kato, Merii; Sah, Ajay Kumar; Tanase, Tomoaki; Mikuriya, Masahiro

2006-08-21

Tetranuclear copper(II) complexes containing alpha-D-glucose-1-phosphate (alpha-D-Glc-1P), [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(bpy)4(H2O)2]X3 [X = NO3 (1a), Cl (1b), Br (1c)], and [Cu4(mu-OH){mu-(alpha-D-Glc-1P)}2(phen)4(H2O)2](NO3)3 (2) were prepared by reacting the copper(II) salt with Na2[alpha-D-Glc-1P] in the presence of diimine ancillary ligands, and the structure of 2 was characterized by X-ray crystallography to comprise four {Cu(phen)}2+ fragments connected by the two sugar phosphate dianions in 1,3-O,O' and 1,1-O mu4-bridging fashion as well as a mu-hydroxo anion. The crystal structure of 2 involves two chemically independent complex cations in which the C2 enantiomeric structure for the trapezoidal tetracopper(II) framework is switched according to the orientation of the alpha-D-glucopyranosyl moieties. Temperature-dependent magnetic susceptibility data of 1a indicated that antiferromagnetic spin coupling is operative between the two metal ions joined by the hydroxo bridge (J = -52 cm(-1)) while antiferromagnetic interaction through the Cu-O-Cu sugar phosphate bridges is weak (J = -13 cm(-1)). Complex 1a readily reacted with carboxylic acids to afford the tetranuclear copper(II) complexes, [Cu4{mu-(alpha-D-Glc-1P)}2(mu-CA)2(bpy)4](NO3)2 [CA = CH3COO (3), o-C6H4(COO)(COOH) (4)]. Reactions with m-phenylenediacetic acid [m-C6H4(CH2COOH)2] also gave the discrete tetracopper(II) cationic complex [Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)(CH2COOH))2(bpy)4](NO3)2 (5a) as well as the cluster polymer formulated as {[Cu4{mu-(alpha-D-Glc-1P)}2(mu-m-C6H4(CH2COO)2)(bpy)4](NO3)2}n (5b). The tetracopper structure of 1a is converted into a symmetrical rectangular core in complexes 3, 4, and 5b, where the hydroxo bridge is dissociated and, instead, two carboxylate anions bridge another pair of Cu(II) ions in a 1,1-O monodentate fashion. The similar reactions were applied to incorporate sugar acids onto the tetranuclear copper(II) centers. Reactions of 1a with delta

Calculation of exchange coupling constants in triply-bridged dinuclear Cu(II) compounds based on spin-flip constricted variational density functional theory.

Science.gov (United States)

Seidu, Issaka; Zhekova, Hristina R; Seth, Michael; Ziegler, Tom

2012-03-08

The performance of the second-order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) for the calculation of the exchange coupling constant (J) is assessed by application to a series of triply bridged Cu(II) dinuclear complexes. A comparison of the J values based on SF-CV(2)-DFT with those obtained by the broken symmetry (BS) DFT method and experiment is provided. It is demonstrated that our methodology constitutes a viable alternative to the BS-DFT method. The strong dependence of the calculated exchange coupling constants on the applied functionals is demonstrated. Both SF-CV(2)-DFT and BS-DFT affords the best agreement with experiment for hybrid functionals.

mu(2)-Oxido bridged dinuclear vanadium(V) complex: synthesis and characterization

Czech Academy of Sciences Publication Activity Database

Ghorbani, M.; Khalaji, A.D.; Feizi, N.; Akbari, A.; Eigner, Václav; Dušek, Michal

2017-01-01

Roč. 1130, Feb (2017), s. 442-446 ISSN 0022-2860 R&D Projects: GA ČR(CZ) GA15-12653S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : vanadium(V) complex * Schiff base * dinuclear * octahedral Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 1.753, year: 2016

Reactivity of uranium(IV) bridged chalcogenido complexes UIV–E–UIV (E = S, Se) with elemental sulfur and selenium: synthesis of polychalcogenido-bridged uranium complexes

OpenAIRE

Franke, Sebastian M.; Heinemann, Frank W.; Meyer, Karsten

2014-01-01

We report the syntheses, electronic properties, and molecular structures of a series of polychalcogenido-bridged dinuclear uranium species. These complexes are supported by the sterically encumbering but highly flexible, single N-anchored tris(aryloxide) chelator (AdArO)3N3−. Reaction of an appropriate uranium precursor, either the U(III) starting material, [((AdArO)3N)U(DME)], or the dinuclear mono-chalcogenido-bridged uranium(IV/IV) compounds [{((AdArO)3N)U(DME)}2(μ-E)] (E = S, Se), with el...

Two-dimensional structure of poly[[[μ2-1,4-bis(pyridin-4-ylbutane]bis(μ4-pentanedioatodicopper(II] acetonitrile disolvate

Directory of Open Access Journals (Sweden)

Do Nam Lee

2017-10-01

Full Text Available In the title compound, {[Cu2(μ4-C5H6O42(μ2-C14H16N2]·2CH3CN}n, the Cu2 dinuclear units are connected by glutartate ligands, forming one-dimensional double chains. These chains, are in turn bridged by 1,4-bis(pyridin-4-ylbutane ligands to form a two-dimensional layer structure parallel to (112. The carboxylate groups of the glutarate ligand bridge two copper(II ions, forming a paddle-wheel-type Cu2(CO24 dinuclear secondary building unit. A crystallographic inversion centre is located midway between two CuII ions, with a Cu...Cu distance of 2.639 (3 Å. The coordination geometry of the unique CuII ion is slightly disorted square pyramidal, formed by four equatorial carboxylate O atoms and an axial pyridyl N atom.

Template Syntheses, Crystal Structures and Supramolecular Assembly of Hexaaza Macrocyclic Copper(II) Complexes

International Nuclear Information System (INIS)

Kim, Taehyung; Kim, Ju Chang; Lough, Alan J.

2013-01-01

Two new hexaaza macrocyclic copper(II) complexes were prepared by a template method and structurally characterized. In the solid state, they were self-assembled by intermolecular interactions to form the corresponding supramolecules 1 and 2, respectively. In the structure of 1, the copper(II) macrocycles are bridged by a tp ligand to form a macrocyclic copper(II) dimer. The dimer extends its structure by intermolecular forces such as hydrogen bonds and C-H···π interactions, resulting in the formation of a double stranded 1D supramolecule. In 2, the basic structure is a monomeric copper(II) macrocycle with deprotonated imidazole pendants. An undulated 1D hydrogen bonded array is achieved through hydrogen bonds between imidazole pendants and secondary amines, where the imidazole pendants act as a hydrogen bond acceptor. The 1D hydrogen bonded supramolecular chain is supported by C-H···π interactions between the methyl groups of acetonitrile ligands and imidazole pendants of the copper(II) macrocycles. In both complexes, the introduction of imidazoles to the macrocycle as a pendant plays an important role for the formation of supramolecules, where they act as intermolecular hydrogen bond donors and/or acceptors, C-H···π and π-π interactions

Synthesis and properties of a trinuclear copper(II) complex with trithiocyanurate bridge

Czech Academy of Sciences Publication Activity Database

Kopel, P.; Čermáková, Š.; Doležal, Karel; Kalińska, B.; Bieńko, A.; Mroziński, J.

2007-01-01

Roč. 81, č. 3 (2007), s. 327-335 ISSN 0137- 5083 Institutional research plan: CEZ:AV0Z50380511 Keywords : copper(II) * trithiocyanuric acid complexes * magnetic properties Subject RIV: CA - Inorganic Chemistry Impact factor: 0.483, year: 2007 http://ichf.edu.pl/pjch/pj-2007/pj-2007-03a.pdf

SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF A Zn(II COORDINATION POLYMER BASED ON 4,4’-BIPYRIDINE AND ACETATO

Directory of Open Access Journals (Sweden)

LI-HUA WANG

2015-05-01

Full Text Available A novel Zn(II coordination polymer, [Zn(bpy(acetato2]n (bpy = 4,4’-bipyridine, has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Zn(II coordination polymer is triclinic, space group P-1 with a = 8.046(3 Å, b = 9.161(3 Å, c = 10.663(3 Å, α = 109.769(4º, β = 99.966(5º, γ = 101.666(5º, V= 699.1(4 Å3, Z = 2, Dc = 1.614 mg·m-3, μ = 1.774 mm-1, F(000 = 348, and final R1 = 0.0541, ωR2 = 0.1605. X-ray diffraction analysis reveals that the Zn(II center is six-coordination with a N2O4 distorted octahedral coordination environment. The Zn(II complex forms 1D chain structure by the bridge of 4,4’-bipyridine and acetato.

EPR studies on binuclear copper(II) complexes with N,N',N'',N'''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraaza-cyclotetradecane in solutions

International Nuclear Information System (INIS)

Jezierska, J.; Ozarowski, A.; Vuckovic, G.

1997-01-01

Binuclear copper(II) complexes of macrocyclic ligand TMPC (tetraazamacrocycle with four pendant 2-pirydylmethyl groups attached to the ring nitrogen atoms) with various anions forming bridge between copper ions, or coordinating to copper(II) ions at the apex, were prepared and their frozen solutions in DMF and NMF were investigated by EPR. The spectroscopic results have been interpreted in terms of molecular structure of investigated complexes

Changes in magnetic properties from solid state to solution in a trinuclear linear copper(II) complex

NARCIS (Netherlands)

Koval, I.A.; Akhideno, H.; Tanase, S.; Belle, C.; Duboc, C.; Saint-Aman, E.; Gamez, P.; Tooke, D.M.; Spek, A.L.; Pierre, J.-L.; Reedijk, J.

2007-01-01

A linear trinuclear copper(II) complex containing phenoxido- and alkoxido-bridges between the metal centers has been isolated and structurally characterized. The complex cation consists of a linear array of three copper ions, assembled by means of two doubly deprotonated ligands. The octahedral

COMPARTIMENTACIÓN INTRACELULAR DEL ACETATO EN ASTROCITOS DURANTE LA PRELACTANCIA

Directory of Open Access Journals (Sweden)

A. Salazar-Amado

2005-12-01

Full Text Available El gasto energético es tan grande en el momento del nacimiento, que las neuronas no podrían sobrevivir sin el soporte metabólico de los astrocitos. Adicionalmente, la necesidad de neurotransmisores es tan alta en la prelactancia, que sin la colaboración metabólica de los astrocitos sería imposible mantener los niveles de intermediarios del ciclo de los ácidos tricarboxílicos para mantener su síntesis.Este trabajo se enfocó en el estudio de los procesos metabólicos intracelulares de los astrocitos donde está involucrado el acetato para establecer su importancia en el metabolismo oxidativo y lipogénico durante la prelactancia. Se incubaron cultivos quiescentes de astrocitos neonatales de rata con acetato (5 mM, [1-14C]-acetato, [2-14C]-acetato y [U-14C]-acetato (1 µ Ci (200-300 dpm/nmol. Adicionalmente, se utilizaron inhibidores enzimáticos como el dicloroacetato (1 mM y el aminooxiacetato (5 mM, e inhibidores del transporte como el α-ciano-4-hidroxicinnamato (2 mM, butilmalonato (5 mM y 1,2,3-bencenotricarboxílato (5 mM. Los resultados en su conjunto indican que los astrocitos pueden metabolizar acetato más como sustrato energético que lipogénico, lo que nos permite pensar que este sustrato puede llegar a ser más importante para ayudar a mantener el metabolismo oxidativo, favoreciendo el reciclaje de carbonos en la prelactancia. Adicionalmente, se evidenció con el uso de [1-14C]-acetato una alta actividad anaplerótica sobre todo cuando los astrocitos requieren mantener los reservorios de oxalacetato y acetil-CoA para mantener la respiración. Estos resultados señalan a la acetil-CoA sintetasa mitocondrial (AceCS2, la piruvato carboxilasa (PC y la enzima málica citosólica (cME, como enzimas claves para mantener el funcionamiento de los astrocitos en la prelactancia. Con el uso de [2-14C]-acetato, los resultados sugieren que los astrocitos in vitro tienen un alto requerimiento de carbonos, principalmente para la s

COMPARTIMENTACIÓN INTRACELULAR DEL ACETATO EN NEURONAS DURANTE LA PRELACTANCIA

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B. Barrios-Socha

2006-06-01

Full Text Available En la transición a la vida extrauterina, el recién nacido sufre un período de ayuno (prelactancia que transcurre entre el cese de la nutrición placentaria y la instauración de la lactancia. El gasto de energía por las neuronas es tan alto en estas circunstancias, que la glucogenólisis es incapaz de restablecer los niveles de glucosa en la sangre. En consecuencia, durante la prelactancia debe haber otros sustratos energéticos y lipogénicos, que adicionalmente ayuden a mantener la síntesis de neurotransmisores.Este trabajo establece la importancia de acetato en el metabolismo oxidativo y del lipogénico en neuronas durante la prelactancia. Se determinaron las velocidades de oxidación y lipogénesis en cultivos quiescentes de neuronas fetales de rata incubadas con acetato (5 mM, [1- 14C]-acetato, [2- 14C]-acetato y [U- 14C]-acetato(200-300dpm/nmol Adicionalmente, se utilizaron inhibidores enzimáticos como el dicloroacetato(1 mM y el aminooxiacetato (5 mM, e inhibidores del transporte como el α-ciano-4-hidroxicinnamato(2 mM, butilmalonato (5 mM y 1,2,3-bencenotricarboxilato (5 mM.Los resultados en su conjunto indican que las neuronas pueden metabolizar acetato más como sustrato energético que lipogénico, lo que nos permite pensar que este sustrato puede llegar a ser más importante para ayudar a mantener el metabolismo oxidativo, favoreciendo el reciclaje de carbonos en la prelactancia.Adicionalmente, se evidenció con el uso de [1-14C]-acetato una alta actividad anaplerótica sobre todo cuando las neuronas requieren mantener los reservorios de oxalacetato y acetil-CoA para mantener la respiración. Estos resultados señalan a la acetil-CoA sintetasa (AceCS2 y la enzima málica (mME mitocondriales, como enzimas claves para mantener el funcionamiento de las neuronas en la prelactancia.Con el uso de [2-14C]-acetato, los resultados sugieren que las neuronas tienen un alto requerimiento de carbonos, principalmente para la síntesis de

Tuning affinity and reversibility for O₂ binding in dinuclear Co(II) complexes

DEFF Research Database (Denmark)

Vad, Mads Sørensen; Johansson, Frank Bartnik; Seidler-Egdal, Rune Kirk

2013-01-01

The O2 binding affinity of a series of dicobalt(II) complexes can be tuned between p(O2)50% = 2.3 × 10−3 and 700 × 10−3 atm at 40 °C by varying the number of H and Cl atoms in the bridging acetato ligands of [Co2(bpbp)(CH(3−n)ClnCO2)(CH3CN)2]2+, where bpbp− = 2,6-bis(N,N-bis(2-pyridylmethyl)amino...

Dihydroxo-bridged dimeric Cu(II) system containing sandwiched non-coordinating phenylacetate anion: Crystal structure, spectroscopic, anti-bacterial, anti-fungal and DNA-binding studies of [(phen)(H2O)Cu(OH)2Cu(H2O)(phen)]2L.6H2O: (HL = phenylacetic acid; phen = 1,10-phenanthroline)

Science.gov (United States)

Iqbal, Muhammad; Ali, Saqib; Tahir, Muhammad Nawaz; Shah, Naseer Ali

2017-09-01

This paper reports the synthesis, X-ray crystal structure, DNA-binding, antibacterial and antifungal studies of a rare dihydroxo-bridged dinuclear copper(II) complex including 1,10-phenanthroline (Phen) ligands and phenylacetate (L) anions, [Cu2(Phen)2(OH)2(H2O)2].2L.6H2O. Structural data revealed distorted square-pyramidal geometry for each copper(II) atom with the basal plane formed by the two nitrogen atoms of the phenantroline ligand and the oxygen atoms of two bridging hydroxyl groups. The apical positions are filled by the oxygen atom from a water molecule. This forms a centrosymmetric cationic dimer where the uncoordinated phenylacetate ligands serve to balance the electrical charge. The dimers interact by means of hydrogen bonds aided by the coordinated as well as uncoordinated water molecules and phenyl-acetate moieties in the crystal lattice. The binding ability of the complex with salmon sperm DNA was determined using cyclic voltammetry and absorption spectroscopy yielding binding constants 2.426 × 104 M-1 and 1.399 × 104 M-1, respectively. The complex was screened against two Gram-positive (Micrococcus luteus and Bacillus subtilis) and one Gram-negative (Escherichia coli) bacterial strains exhibiting significant activity against all the three strains. The complex exhibited significant, moderate and no activity against fungal strains Mucor piriformis, Helminthosporium solani and Aspergillus Niger, respectively. These preliminary tests indicate the competence of the complex towards the development of a potent biological drug.

Mono- and dinuclear bioxazoline-palladium complexes for the stereocontrolled synthesis of CO/styrene polyketones.

Science.gov (United States)

Scarel, Alessandro; Durand, Jérôme; Franchi, Davide; Zangrando, Ennio; Mestroni, Giovanni; Carfagna, Carla; Mosca, Luca; Seraglia, Roberta; Consiglio, Giambattista; Milani, Barbara

2005-10-07

The coordination chemistry of the chiral bioxazoline ligand (4S,4'S)-2,2'-bis(4-isopropyl-4,5-dihydrooxazole) to Pd(II) provides evidence that the ligand bonding can occur either through chelation of one Pd(II) ion leading to a mononuclear species with the expected cis geometry, or by double bridging of two Pd(II) ions giving a dinuclear complex with trans geometry. The species in solution are identified by 1H NMR spectroscopy. Both the mononuclear and the dinuclear complexes promote the CO/styrene copolymerization, yielding the corresponding polyketone with a fully or a predominantly isotactic microstructure, depending on the reaction medium. The nature of the anion present in the palladium precatalysts affects the polyketone stereochemistry. MALDI-TOF analysis of the copolymers synthesized reveals the presence of p-hydroxyphenolic end-groups, thus confirming and explaining the role of 1,4-hydroquinone as a molecular weight regulator.

Synthesis, crystal structure and DFT studies of a novel dinuclear copper(I) complex with triphenylphosphine and 2-mercaptonicotinic acid

Science.gov (United States)

Ahmad, Tayyaba; Mahmood, Rashid; Georgieva, Ivelina; Zahariev, Tsvetan; Tahir, Muhammad Nawaz; Shaheen, Muhammad Ashraf; Gilani, Mazhar Amjad; Ahmad, Saeed

2018-02-01

A novel dinuclear copper(I) complex, {[Cu2(Mnt)2(PPh3)2Cl2].2H2O.CH3CN}2 (1) (Mnt = Mercaptonicotinic acid, PPh3 = triphenylphosphine) was prepared and its structure was determined by X-ray crystallography. The complex 1 consists of two dinuclear molecules and in each molecule, the two copper atoms are bridged by S atoms of N-protonated mercaptonicotinic acid forming a four-membered ring. The planar Cu2S2 core is characterized by significant cuprophilic interactions (Cusbnd Cu distance = 2.7671(8), 2.8471(8) Å). Each copper atom in 1 is coordinated by two sulfur atoms of Mnt, one phosphorus atom of PPh3 and a chloride ion adopting a tetrahedral geometry. The calculated Gibbs energies for reaction in CH3CN supported the experimental structure and predicted more favorable formation of dinuclear Cu(I) complex as compared to the mononuclear Cu(I) complex. The dinuclear complex is stabilized by 65.98 kJ mol-1 by coupling of two mononuclear Cu(I) complexes. The IR spectra of 1 and Mnt ligand were reliably interpreted and the Mnt vibrations, which are sensitive to the ligand coordination to Cu(I) ion in 1 were selected with the help of DFT/ωB97XD calculations.

Synthesis and Crystal Structure of Dinuclear Cadmium(II) Complex with Dipodal Ligand

International Nuclear Information System (INIS)

Kang, Young Jin; Moon, Suk Hee; Byun, Jong Chul; Park, Ki Min

2010-01-01

the preparation and structural characterization of the discrete dinuclear cadmium(II) complex with the formula [Cd(μ 2 -Cl) 2 Cl 2 ]· 2 (H 2 O)·0.5(CH 3 OH)·0.5(CH 3 CN) obtained from the reaction of CdCl 2 ·2.5H 2 O and podal ligand with quinoline end-groups has been reported. In two cadmium ions are triply bridged by two chloride and one donor atoms of ligand L and adopt distorted pentagonal bipyramidal geometries with seven coordinations. It is notable that example of discrete dinuclear complex which one podal ligand accommodates simultaneously two metal ions is very rare. During the last four decades, the chemistry of macrocyclic and non-cyclic polyethers has attracted an increasing attention because of their selective complexation, cation transport and enzyme chemistry. In the field of coordination chemistry, generally, non-cyclic, crown-type polyether affords the low complexation ability because of its conformational freedom while macrocyclic polyethers such as 18-crown-6 show the excellent complexing ability

Evidence of desulfurization in the oxidative cyclization of thiosemicarbazones. Conversion to 1,3,4-oxadiazole derivatives.

Science.gov (United States)

Gómez-Saiz, Patricia; García-Tojal, Javier; Maestro, Miguel A; Arnaiz, Francisco J; Rojo, Teófilo

2002-03-25

The addition of pyridine-2-carbaldehyde 4N-methylthiosemicarbazone (C8H10N4S) to an aqueous solution of copper(II) nitrate yields [[Cu(C8H9N4S)(NO3)]2] (1). This complex consists of centrosymmetric dinuclear entities containing square-pyramidal copper(II) ions bridged through the sulfur thioamide atoms. The oxidation of 1 with KBrO3 or KIO3 gives rise to a compound with formula [[Cu(C8H8N4O)(H2O)2(SO4)]2]*2H2O (2) (C8H8N4O = 2-methylamino-5-pyridin-2-yl-1,3,4-oxadiazole). The structure of 2 is made up of centrosymmetric dimers where the copper(II) ions exhibit a distorted octahedral coordination and are connected by the oxadiazole moiety. The metal ions in 2 can be removed by addition of K4[Fe(CN)6], and then the oxadiazole ligand can be isolated and recrystallized as (C8H8N4O)*3H2O (3).

Mechanistic insights into toxic effects of a benzotriazolate-bridged dinuclear platinum(II) compound in tumor cells

Czech Academy of Sciences Publication Activity Database

Olivová, R.; Štěpánková, Jana; Muchová, T.; Novohradský, V.; Nováková, Olga; Vrána, Oldřich; Kašpárková, Jana; Brabec, Viktor

2012-01-01

Roč. 393, DEC (2012), s. 204-211 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GAP301/10/0598 Institutional research plan: CEZ:AV0Z50040702 Institutional support: RVO:68081707 Keywords : Dinuclear platinum * Antitumor * DNA binding Subject RIV: BO - Biophysics Impact factor: 1.687, year: 2012

Exchange interactions in a dinuclear manganese (II) complex with cyanopyridine-N-oxide bridging ligands

Energy Technology Data Exchange (ETDEWEB)

Markosyan, A.S. [Faculty of Physics, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Department of Applied Physics, Stanford University (United States); Gaidukova, I.Yu.; Ruchkin, A.V. [Faculty of Physics, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Anokhin, A.O. [Institute of Metal Physics, Ural Division of the Russian, Ekaterinburg (Russian Federation); Irkhin, V.Yu., E-mail: valentin.irkhin@imp.uran.ru [Institute of Metal Physics, Ural Division of the Russian, Ekaterinburg (Russian Federation); Ryazanov, M.V.; Kuz’mina, N.P. [Faculty of Chemistry, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation); Nikiforov, V.N. [Faculty of Physics, M.V. Lomonosov Moscow State University, 119992 Moscow (Russian Federation)

2014-01-01

The magnetic properties of dinuclear manganese(II) complex [Mn(hfa){sub 2}cpo]{sub 2} (where hfa is hexafluoroacetylacetonate anion and cpo is 4-cyanopyridine-N-oxide) are presented. The non-monotonous dependence of magnetic susceptibility is explained in terms of the hierarchy of exchange parameters by using exact diagonalization. The thermodynamic behavior of pure cpo and [Mn(hfa){sub 2}(cpo)]{sub 2} is simulated numerically by an extrapolation to spin S=5/2. The Mn–Mn exchange integral is evaluated.

Synthesis, characterization, crystal structure and antibacterial activity of new sulfur-bridged dinuclear silver(I) thiosemicarbazone complex [Ag.sub.2./sub.(PPh.sub.3./sub.).sub.2./sub.(μ-S-Brcatsc).sub.2./sub.(η.sup.1./sup.-S-Brcatsc).sub.2./sub.](NO.sub.3./sub.).sub.2./sub..

Czech Academy of Sciences Publication Activity Database

Shahsavani, E.; Khalaji, A.D.; Feizi, N.; Kučeráková, Monika; Dušek, Michal

2015-01-01

Roč. 429, Apr (2015), 61-66 ISSN 0020-1693 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : sulfur-bridged dinuclear silver(I) * thiosemicarbazone complex * single-crystal * distorted tetrahedron * antibacterial activity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.918, year: 2015

Chlorodiethylaluminum supported on silica: A dinuclear aluminum surface species with bridging μ2-Cl-ligand as a highly efficient co-catalyst for the Ni-catalyzed dimerization of ethene

KAUST Repository

Kermagoret, Anthony

2014-05-01

Silica-supported chloro alkyl aluminum co-catalysts (DEAC@support) were prepared via Surface Organometallic Chemistry by contacting diethylaluminum chloride (DEAC) and high specific surface silica materials, i.e. SBA-15, MCM-41, and Aerosil SiO2. Such systems efficiently activate NiCl 2(PBu3)2 for catalytic ethene dimerization, with turnover frequency (TOF) reaching up to 498,000 molC2H4/ (molNi h) for DEAC@MCM-41. A detailed analysis of the DEAC@SBA-15 co-catalyst structure by solid-state aluminum-27 NMR at high-field (17.6 T and 20.0 T) and ultrafast spinning rates allows to detect six sites, characterized by a distribution of quadrupolar interaction principal values CQ and isotropic chemical shifts δiso. Identification of the corresponding Al-grafted structures was possible by comparison of the experimental NMR signatures with these calculated by DFT on a wide range of models for the aluminum species (mono- versus di-nuclear, mono- versus bis-grafted with bridging Cl or ethyl). Most of the sites were identified as dinuclear species with retention of the structure of DEAC, namely with the presence of μ2-Cl-ligands between two aluminum, and this probably explains the high catalytic performance of this silica-supported co-catalysts. © 2014 Elsevier Inc. All rights reserved.

Structural and magnetic characterization of a tetranuclear copper(II) cubane stabilized by intramolecular metal cation-π interactions.

Science.gov (United States)

Papadakis, Raffaello; Rivière, Eric; Giorgi, Michel; Jamet, Hélène; Rousselot-Pailley, Pierre; Réglier, Marius; Simaan, A Jalila; Tron, Thierry

2013-05-20

A novel tetranuclear copper(II) complex (1) was synthesized from the self-assembly of copper(II) perchlorate and the ligand N-benzyl-1-(2-pyridyl)methaneimine (L(1)). Single-crystal X-ray diffraction studies revealed that complex 1 consists of a Cu4(OH)4 cubane core, where the four copper(II) centers are linked by μ3-hydroxo bridges. Each copper(II) ion is in a distorted square-pyramidal geometry. X-ray analysis also evidenced an unusual metal cation-π interaction between the copper ions and phenyl substituents of the ligand. Calculations based on the density functional theory method were used to quantify the strength of this metal-π interaction, which appears as an important stabilizing parameter of the cubane core, possibly acting as a driving parameter in the self-aggregation process. In contrast, using the ligand N-phenethyl-1-(2-pyridyl)methaneimine (L(2)), which only differs from L(1) by one methylene group, the same synthetic procedure led to a binuclear bis(μ-hydroxo)copper(II) complex (2) displaying intermolecular π-π interactions or, by a slight variation of the experimental conditions, to a mononuclear complex (3). These complexes were studied by X-ray diffraction techniques. The magnetic properties of complexes 1 and 2 are reported and discussed.

EPR interpretation, magnetism and biological study of a Cu(II) dinuclear complex assisted by a schiff base precursor.

Science.gov (United States)

Das, Kuheli; Patra, Chiranjit; Sen, Chandana; Datta, Amitabha; Massera, Chiara; Garribba, Eugenio; El Fallah, Mohamed Salah; Beyene, Belete B; Hung, Chen-Hsiung; Sinha, Chittaranjan; Askun, Tulin; Celikboyun, Pinar; Escudero, Daniel; Frontera, Antonio

2017-06-01

A new Cu(II) dinuclear complex, Cu 2 L 2 (1) was afforded employing the potentially pentatentate Schiff base precursor H 2 L, a refluxed product of o-vanillin and diethylenetriamine in methanol. Complex 1 was systematically characterized by FTIR, UV-Vis, emission and EPR spectrometry. The single crystal X-ray diffraction analysis of 1 reveals that the copper atom exhibits a distorted square planar geometry, comprising two pairs of phenolato-O and imine-N donors from two different H 2 L ligands. The temperature dependent magnetic interpretation agrees with the existence of weak antiferromagnetic interactions between the bridging dinuclear Cu(II) ions. A considerable body of experimental evidence has been accumulated to elucidate the magneto-structural relationship in this dinuclear Cu(II) complex by DFT computation. Both the ligand and complex 1 exhibit anti-mycobacterial activity and considerable efficacy on M. tuberculosis H 37 Ra (ATCC 25177) and M. tuberculosis H 37 Rv (ATCC 25618) strains. The practical applicability of the ligand and complex 1 has been examined in living cells (African Monkey Vero Cells). The MTT assay proves the non-toxicity of the probe up to 100 mg mL -1 . A new homometallic dinuclear Cu(II) complex is afforded with a tetradentate Schiff base precursor. EPR interpretation and temperature dependent magnetic studies show that complex 1 has weak antiferromagnetic coupling and DFT computation is governed to explain the magneto-structural correlation.

Dinuclear Silver(I) and Copper(II) Complexes of Hexadentate Macrocyclic Ligands Containing p-Xylyl Spacers

DEFF Research Database (Denmark)

McKenzie, Christine J.; Nielsen, Lars Preuss; Søtofte, Inger

1998-01-01

The cyclocondensation of terephthalic aldehyde with N,N-bis(3-aminopropyl)-methylamine in the presence of silver(I) gives the dinuclear tetramine Schiff base macrocyclic complex, [Ag2L1](NO3)2 (L1=7,22-N,N'-dimethyl-3,7,11,18, 22,26-hexaazatricyclo[26.2.21.18.213.16]-tetratricosa-2,11,13,15,1 7......,26,28,30,31,33-decaene). [Ag2L1](NO3)2 crystallizes in the monoclinic space group P21/c, with a=14.153(6), b=12.263(4), c=9.220(2) Å, beta=97.52(3) Å and Z=2. The silver ions are strongly coordinated at each end of the macrocycle by the two imine nitrogen atoms [2.177(3) and 2.182(3) Å] with close interatomic...... interactions to an oxygen atom of a nitrate ion and an amine nitrogen atom [2.580(2) and 2.690(2) Å]. The Ag...Ag distance is 6.892(3) Å. The free tetraimine macrocycle, L1, was obtained by treatment of [Ag2L1](NO3)2 with an excess of iodide, and the reduced derivative 7,22-N,N'-dimethyl-3...

Dinuclear NHC-palladium complexes containing phosphine spacers: synthesis, X-ray structures and their catalytic activities towards the Hiyama coupling reaction.

Science.gov (United States)

Yang, Jin; Li, Pinhua; Zhang, Yicheng; Wang, Lei

2014-05-21

Six dinuclear N-heterocyclic carbene (NHC) palladium complexes, [PdCl2(IMes)]2(μ-dppe) (1), [PdCl2(IPr)]2(μ-dppe) (2), [PdCl2(IMes)]2(μ-dppb) (3), [PdCl2(IPr)]2(μ-dppb) (4), [PdCl2(IMes)]2(μ-dpph) (5), and [PdCl2(IPr)]2(μ-dpph) (6) [IMes = N,N'-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene; IPr = N,N'-bis-(2,6-di(iso-propyl)phenyl)imidazol-2-ylidene; dppe = 1,2-bis(diphenylphosphino)ethane, dppb = 1,4-bis(diphenylphosphino)butane; and dpph = 1,6-bis(diphenylphosphino)hexane], have been synthesized through bridge-cleavage reactions of chloro-bridged dimeric compounds, [Pd(μ-Cl)(Cl)(NHC)]2, with the corresponding diphosphine ligands. The obtained compounds were fully characterized by (1)H NMR, (13)C NMR and (31)P NMR spectroscopy, FT-IR, elemental analysis and single-crystal X-ray crystallography. Moreover, further explorations of the catalytic potential of the dinuclear carbene palladium complexes as catalysts for the Pd-catalyzed transformations have been performed under microwave irradiation conditions, and the complexes exhibited moderate to good catalytic activity in the Hiyama coupling reaction of trimethoxyphenylsilane with aryl chlorides.

COMPARTIMENTACIÓN INTERCELULAR DEL ACETATO EN NEURONAS Y ASTROCITOS DURANTE LA PRELACTANCIA

Directory of Open Access Journals (Sweden)

J. Tovar-Franco

2005-12-01

Full Text Available Durante el período perinatal el cerebro utiliza sustratos alternativos a la glucosa para mantener su desarrollo, pues en este momento sus niveles están disminuidos. El acetato es metabolizado por las neuronas y los astrocitos durante la prelactancia. La utilización del acetato por estas células puede verse mejorada por lasreacciones fijadoras de CO2, algunas de las cuales participan en el mantenimiento de los intermediarios del TCA, que son reducidos por la producción y liberación de aminoácidos, suministrando los recursos para la producción de energía y sustratos que son compartimentados intercelularmente.Se estudió el efecto de la fijación de CO2 en procesos metabólicos intercelulares donde está involucrado el acetato. En incubaciones con neuronas y astrocitos de 7 y 14 días de cultivo, utilizando acetato (5 mM y [14C]-bicarbonato de sodio (10 µ Ci (500-1000 dpm/nmol, se determinó la incorporación en metabolitos marcados en células y en sustratos estables liberados al medio. Adicionalmente, se realizaron experimentos similares utilizando inhibidores como el aminooxiacetato (AOA, dicloroacetato (DCA, α-ciano-4-hidroxicinnamato (α-CN, butilmalonato (BM y bencenotricarboxílato (BT, cuantificando porcromatografía de capa delgada la concentración en el medio de incubación de alanina, aspartato, glutamato y glutamina.Los resultados indican que las neuronas tienen una menor capacidad para fijar carbonos en estructuras celulares, durante la prelactancia, pero utilizan mejor el acetato vía acetil-CoA mitocondrial (AceCS2 para la producción de energía y aminoácidos. En los astrocitos, estas reacciones favorecen la utilización del acetato vía citrato liasa y Acetil-CoA citosólica (AceCS1 para la producción de estructuras y sustratos utilizados por las neuronas, que para la producción de aminoácidos.

A comparative study of the structure and luminescence of mono- and dinuclear crown-ether lanthanide complexes

Energy Technology Data Exchange (ETDEWEB)

Souza, Keyla M.N. de [Departamento de Química, Universidade Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, S/N – Dois Irmãos, 52171-900 Recife, Pernambuco (Brazil); Batista, Hélcio J., E-mail: helciojb@gmail.com [Departamento de Química, Universidade Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, S/N – Dois Irmãos, 52171-900 Recife, Pernambuco (Brazil); Belian, Mônica F. [Departamento de Química, Universidade Federal Rural de Pernambuco, Rua Dom Manoel de Medeiros, S/N – Dois Irmãos, 52171-900 Recife, Pernambuco (Brazil); Silva, Wagner E. [Unidade Acadêmica do Cabo de Santo Agostinho, Universidade Federal Rural de Pernambuco, 54510-000 Cabo de Santo Agostinho, Pernambuco (Brazil); Silva, Juliana A.B. da [Centro Acadêmico do Agreste, Universidade Federal de Pernambuco, 55002-970 Caruaru, Pernambuco (Brazil)

2016-02-15

peculiar electronic properties of the siloxane group, which has a partial character of (p–d)π hyperconjugation. Results of quantum chemical theoretical calculations of molecular and electronic structures, using DFT methods, reinforce such special properties of the siloxane and also show that its presence is responsible for considerable differences in the coordination sphere between the mono- and dinuclear species, such as in the coordination number, which decreases from nine to seven. Furthermore, particularly in the dinuclear [Eu{sub 2}SW{sub 8}]{sup 6+} complex, one water molecule per coordination center suffers a hydrolysis, donating a proton to the near NH{sub 2} of an amino–propyl function, present in the siloxane group bridging the two mononuclear moieties, and this event could also be related with the observed enhanced luminescence. - Highlights: • Dinuclear Ln(III) complexes (Ln=Eu; Gd; Tb) based on silacrown ether. • The Eu{sub 2}SW{sub 8} dinuclear complex is much more luminescent than its mononuclear analog. • DFT calculations confirm some peculiar electronic properties of siloxane group. • DFT results suggest coordination changes from mono- to dinuclear case.

X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

Energy Technology Data Exchange (ETDEWEB)

DeWitt, J.G.

1992-12-01

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 [Angstrom]. The Fe-Fe distance was determined to be 3.4 [Angstrom]. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

X-ray absorption spectroscopic studies of the dinuclear iron center in methane monooxygenase and the sulfure and chlorine centers in photographic materials

Energy Technology Data Exchange (ETDEWEB)

DeWitt, Jane G. [Stanford Univ., CA (United States)

1992-12-01

The dinuclear iron center of the hydroxylase component of soluble methane monooxygenase (MMO) from Methylococcus capsulatus and Methylosinus trichosporiwn has been studied by X-ray absorption spectroscopy. Analysis of the Fe K-edge EXAFS revealed that the first shell coordination of the Fe(HI)Fe(IH) oxidized state of the hydroxylase from M. capsulatus consists of approximately 6 N and 0 atoms at an average distance of 2.04 Å. The Fe-Fe distance was determined to be 3.4 Å. No evidence for the presence of a short oxo bridge in the iron center of the oxidized hydroxylase was found, suggesting that the active site of MMO is significantly different from the active sites of the dinuclear iron proteins hemery and ribonucleotide reductase. In addition, the results of the first shell fits suggest that there are more oxygen than nitrogen donor ligands.

Supramolecular architecture of metal-organic frameworks involving dinuclear copper paddle-wheel complexes.

Science.gov (United States)

Gomathi, Sundaramoorthy; Muthiah, Packianathan Thomas

2013-12-15

The two centrosymmetric dinuclear copper paddle-wheel complexes tetrakis(μ-4-hydroxybenzoato-κ(2)O:O')bis[aquacopper(II)] dimethylformamide disolvate dihydrate, [Cu2(C7H5O3)4(H2O)2]·2C3H7NO·2H2O, (I), and tetrakis(μ-4-methoxybenzoato-κ(2)O:O')bis[(dimethylformamide-κO)copper(II)], [Cu2(C8H7O3)4(C3H7NO)2], (II), crystallize with half of the dinuclear paddle-wheel cage unit in the asymmetric unit and, in addition, complex (I) has one dimethylformamide (DMF) and one water solvent molecule in the asymmetric unit. In both (I) and (II), two Cu(II) ions are bridged by four syn,syn-η(1):η(1):μ carboxylate groups, showing a paddle-wheel cage-type structure with a square-pyramidal coordination geometry. The equatorial positions of (I) and (II) are occupied by the carboxylate groups of 4-hydroxy- and 4-methoxybenzoate ligands, and the axial positions are occupied by aqua and DMF ligands, respectively. The three-dimensional supramolecular metal-organic framework of (I) consists of three different R2(2)(20) and an R4(4)(36) ring motif formed via O-H···O and OW-HW···O hydrogen bonds. Complex (II) simply packs as molecular species.

Photocleavage of DNA by copper(II) complexes

Indian Academy of Sciences (India)

The chemistry of ternary and binary copper(II) complexes showing efficient visible lightinduced DNA cleavage activity is summarized in this article. The role of the metal in photo-induced DNA cleavage reactions is explored by designing complex molecules having a variety of ligands. Ternary copper(II) complexes with amino ...

Highly Luminescent Dinuclear Platinum(II) Complexes Incorporating Bis-Cyclometallating Pyrazine-Based Ligands: A Versatile Approach to Efficient Red Phosphors

OpenAIRE

Culham, Stacey; Lanoe, Pierre-Henri; Whittle, Victoria; Durrant, Marcus; Williams, Gareth; Kozhevnikov, Valery

2013-01-01

A series of luminescent dinuclear platinum(II) complexes incorporating diphenylpyrazine-based bridging ligands ((LH2)-H-n) has been prepared. Both 2,5-diphenylpyrazine ((LH2)-H-2) and 2,3-diphenylpyrazine ((LH2)-H-3) are able to undergo cyclometalation of the two phenyl rings, with each metal ion binding to the two nitrogen atoms of the central heterocycle, giving, after treatment with the anion of dipivaloyl methane (dpm), complexes of formula \\{Pt(dpm)\\}(2)L-n. These compounds are isomers o...

DFT description of the magnetic properties and electron localization in dinuclear di-mu-oxo-bridged manganese complexes.

Science.gov (United States)

Barone, Vincenzo; Bencini, Alessandro; Gatteschi, Dante; Totti, Federico

2002-11-04

Density functional theory (DFT) was applied to describe the magnetic and electron-transfer properties of dinuclear systems containing the [MnO2Mn]n+ core, with n=0,1,2,3,4. The calculation of the potential energy surfaces (PESs) of the mixed-valence species (n=1,3) allowed the classification of these systems according to the extent of valence localization as Class II compounds, in the Robin-Day classification scheme. The fundamental frequencies corresponding to the asymmetric breathing vibration were also computed.

When two are better than one: bright phosphorescence from non-stereogenic dinuclear iridium(III) complexes.

Science.gov (United States)

Daniels, Ruth E; Culham, Stacey; Hunter, Michael; Durrant, Marcus C; Probert, Michael R; Clegg, William; Williams, J A Gareth; Kozhevnikov, Valery N

2016-04-28

A new family of eight dinuclear iridium(iii) complexes has been prepared, featuring 4,6-diarylpyrimidines L(y) as bis-N^C-coordinating bridging ligands. The metal ions are also coordinated by a terminal N^C^N-cyclometallating ligand L(X) based on 1,3-di(2-pyridyl)benzene, and by a monodentate chloride or cyanide. The general formula of the compounds is {IrL(X)Z}2L(y) (Z = Cl or CN). The family comprises examples with three different L(X) ligands and five different diarylpyrimidines L(y), of which four are diphenylpyrimidines and one is a dithienylpyrimidine. The requisite proligands have been synthesised via standard cross-coupling methodology. The synthesis of the complexes involves a two-step procedure, in which L(X)H is reacted with IrCl3·3H2O to form dinuclear complexes of the form [IrL(X)Cl(μ-Cl)]2, followed by treatment with the diarylpyrimidine L(y)H2. Crucially, each complex is formed as a single compound only: the strong trans influence of the metallated rings dictates the relative disposition of the ligands, whilst the use of symmetrically substituted tridentate ligands eliminates the possibility of Λ and Δ enantiomers that are obtained when bis-bidentate units are linked through bridging ligands. The crystal structure of one member of the family has been obtained using a synchrotron X-ray source. All of the complexes are very brightly luminescent, with emission maxima in solution varying over the range 517-572 nm, according to the identity of the ligands. The highest-energy emitter is the cyanide derivative whilst the lowest is the complex with the dithienylpyrimidine. The trends in both the absorption and emission energies as a function of ligand substituent have been rationalised accurately with the aid of TD-DFT calculations. The lowest-excited singlet and triplet levels correlate with the trend in the HOMO-LUMO gap. All the complexes have quantum yields that are close to unity and phosphorescence lifetimes - of the order of 500 ns - that are

Centrifugal fragmentation of a dinuclear system in the process of its evolution toward a compound nucleus

International Nuclear Information System (INIS)

Volkov, V. V.

2007-01-01

The centrifugal fragmentation of a dinuclear system in the process of evolution toward a compound nucleus is examined. If the angular momentum in the collision of primary nuclei is quite high, centrifugal forces become dominant at the final stage of the evolution of the dinuclear system formed, causing the decay of this dinuclear system to two strongly asymmetric nuclear fragments. Experimental data in which this specific nuclear process manifests itself are presented. Centrifugal fragmentation makes it possible to reveal the cluster facet of the evolution of a dinuclear system toward a compound nucleus. The possibility of this fragmentation process is a logical consequence of the concept of a dinuclear system for the complete fusion of nuclei

Synthesis of 2D polymeric dicyanamide bridged hexa-coordinated Cu(II) complex: Structural characterization, spectral studies and TDDFT calculation

Science.gov (United States)

Konar, Saugata; Saha, Urmila; Dolai, Malay; Chatterjee, Sudipta

2014-10-01

A rare 2D polymeric dicyanamide bridged hexa-coordinated copper(II) complex [Cu(L1‧)(μ1,5-dca)2]n (1) (L1‧ = 2-carboxypyrazine) has been synthesized from the reaction of Cu(NO3)2ṡ6H2O, 2-pyrazinecarbonitrile (L1) and sodium dicyanamide (Nadca) in methanolic medium. Single crystal X-ray analysis reveals that the complex has a 2D infinite zigzag chain structure in which copper(II) ions are bridged by single dicyanamide ligand in an end-to-end fashion. Such 2-carboxypyrazine can be obtained on the way of metal-assisted nitrile hydrolysis which well connected with Cu(NO3)2ṡ6H2O and dicyanamide (dca) to give rare 2D Cu(II) polymeric complex due to the flexibility in the coordination ability of the copper(II) ions within the polymeric chain. The geometry of the asymmetric unit of the complex was optimized in singlet state by DFT method with multilayer ONIOM model at doublet spin state accordance with repeating asymmetric unit only. The electronic spectrum of the complex is explained using TDDFT calculation.

μ-Oxalato-bis[(2,2′-bipyridylcopper(II] bis(perchlorate dimethylformamide disolvate monohydrate

Directory of Open Access Journals (Sweden)

Alexander N. Boyko

2010-09-01

Full Text Available The title compound, [Cu2(C2O4(C10H8N24](ClO42·2C3H7NO·H2O, contains doubly charged centrosymmetric dinuclear oxalato-bridged copper(II complex cations, perchlorate anions, and DMF and water solvate molecules. In the complex cation, the oxalate ligand is coordinated in a bis-bidentate bridging mode to the Cu atoms. Each Cu atom has a distorted tetragonal-bipyramidal environment, being coordinated by two N atoms of the two chelating bipy ligands and two O atoms of the doubly deprotonated oxalate anion. Pairs of perchlorate anions and water molecules are linked into rectangles by O—H...O bonds in which the perchlorate O atoms act as acceptors and the water molecules as donors. Methyl groups of the DMF solvent molecule are disordered over two sites with occupancies of 0.453 (7:0.547 (7, and the water molecule is half-occupied.

Magneto-structural correlations in trinuclear Cu(II) complexes: a density functional study

CERN Document Server

Rodríguez-Forteá, A; Alvarez, S; Centre-De Recera-En-Quimica-Teorica; Alemany, P A; Centre-De Recera-En-Quimica-Teorica

2003-01-01

Density functional theoretical methods have been used to study magneto-structural correlations for linear trinuclear hydroxo-bridged copper(II) complexes. The nearest-neighbor exchange coupling constant shows very similar trends to those found earlier for dinuclear compounds for which the Cu-O-Cu angle and the out of plane displacement of the hydrogen atoms at the bridge are the two key structural factors that determine the nature of their magnetic behavior. Changes in these two parameters can induce variations of over 1000 cm sup - sup 1 in the value of the nearest-neighbor coupling constant. On the contrary, coupling between next-nearest neighbors is found to be practically independent of structural changes with a value for the coupling constant of about -60 cm sup - sup 1. The magnitude calculated for this coupling constant indicates that considering its value to be negligible, as usually done in experimental studies, can lead to considerable errors, especially for compounds in which the nearest-neighbor c...

Multiple-decker phthalocyaninato dinuclear lanthanoid(III) single-molecule magnets with dual-magnetic relaxation processes.

Science.gov (United States)

Katoh, Keiichi; Horii, Yoji; Yasuda, Nobuhiro; Wernsdorfer, Wolfgang; Toriumi, Koshiro; Breedlove, Brian K; Yamashita, Masahiro

2012-11-28

The SMM behaviour of dinuclear Ln(III)-Pc multiple-decker complexes (Ln = Tb(3+) and Dy(3+)) with energy barriers and slow-relaxation behaviour were explained by using X-ray crystallography and static and dynamic susceptibility measurements. In particular, interactions among the 4f electrons of several dinuclear Ln(III)-Pc type SMMs have never been discussed on the basis of the crystal structure. For dinuclear Tb(III)-Pc complexes, a dual magnetic relaxation process was observed. The relaxation processes are due to the anisotropic centres. Our results clearly show that the two Tb(3+) ion sites are equivalent and are consistent with the crystal structure. On the other hand, the mononuclear Tb(III)-Pc complex exhibited only a single magnetic relaxation process. This is clear evidence that the magnetic relaxation mechanism depends heavily on the dipole-dipole (f-f) interactions between the Tb(3+) ions in the dinuclear systems. Furthermore, the SMM behaviour of dinuclear Dy(III)-Pc type SMMs with smaller energy barriers compared with that of Tb(III)-Pc and slow-relaxation behaviour was explained. Dinuclear Dy(III)-Pc SMMs exhibited single-component magnetic relaxation behaviour. The results indicate that the magnetic relaxation properties of dinuclear Ln(III)-Pc multiple-decker complexes are affected by the local molecular symmetry and are extremely sensitive to tiny distortions in the coordination geometry. In other words, the spatial arrangement of the Ln(3+) ions (f-f interactions) in the crystal is important. Our work shows that the SMM properties can be fine-tuned by introducing weak intermolecular magnetic interactions in a controlled SMM spatial arrangement.

Magnetic exchange couplings from noncollinear perturbation theory: dinuclear CuII complexes.

Science.gov (United States)

Phillips, Jordan J; Peralta, Juan E

2014-08-07

To benchmark the performance of a new method based on noncollinear coupled-perturbed density functional theory [J. Chem. Phys. 138, 174115 (2013)], we calculate the magnetic exchange couplings in a series of triply bridged ferromagnetic dinuclear Cu(II) complexes that have been recently synthesized [Phys. Chem. Chem. Phys. 15, 1966 (2013)]. We find that for any basis-set the couplings from our noncollinear coupled-perturbed methodology are practically identical to those of spin-projected energy-differences when a hybrid density functional approximation is employed. This demonstrates that our methodology properly recovers a Heisenberg description for these systems, and is robust in its predictive power of magnetic couplings. Furthermore, this indicates that the failure of density functional theory to capture the subtle variation of the exchange couplings in these complexes is not simply an artifact of broken-symmetry methods, but rather a fundamental weakness of current approximate density functionals for the description of magnetic couplings.

DENSIDAD, VELOCIDAD DEL SONIDO Y VISCOSIDAD DEL SISTEMA BINARIO ACETATO DE METILO + ACETATO DE BUTILO ENTRE 288,15 Y 318,15 K

Directory of Open Access Journals (Sweden)

Alejandra Mariano

2010-01-01

Full Text Available Fueron determinadas las densidades, velocidades del sonido y viscosidades de la mezcla binaria acetato de metilo + acetato de butilo a 288,15; 293,15; 298,15; 303,15; 308,15; 313,15 y 318,15 K y a presión atmosférica. A partir de la información experimental se calculó el volumen molar de exceso, VE, la desviación de la velocidad del sonido, Δu, la desviación de la viscosidad, Δη, y el exceso de energía de activación por flujo viscoso, ΔG*E, ajustando estos resultados con la ecuación polinomial de Redlich y Kister. La mezcla binaria presentó valores positivos de VE y de ΔG*E, mientras que Δu y Δη resultaron negativos. Se realizó la predicción de la velocidad del sonido con los modelos propuestos por Nomoto, Van Dael y Ernst et al. Las viscosidades de la mezcla se correlacionaron con las ecuaciones de Mc Allister y Katti-Chaudrhi y se aplicaron modelos de contribución de grupos. Se puede concluir que los resultados obtenidos son aceptables.

Determining the Amount of Copper(II) Ions in a Solution Using a Smartphone

Science.gov (United States)

Montangero, Marc

2015-01-01

When dissolving copper in nitric acid, copper(II) ions produce a blue-colored solution. It is possible to determine the concentration of copper(II) ions, focusing on the hue of the color, using a smartphone camera. A free app can be used to measure the hue of the solution, and with the help of standard copper(II) solutions, one can graph a…

Investigation of the interaction of copper(II) oxide and electron beam irradiation crosslinkable polyethylene

International Nuclear Information System (INIS)

Bee, Soo-Tueen; Sin, Lee Tin; Ratnam, C.T.; Haraveen, K.J.S.; Tee, Tiam-Ting; Rahmat, A.R.

2015-01-01

In this study, the effects of electron beam irradiation on the properties of copper(II) oxide when added to low-density polyethylene (LDPE) blends were investigated. It was found that the addition of low loading level of copper(II) oxide (⩽2 phr) to LDPE results in significantly poorer gel content and hot set results. However, the incorporation of higher loading level of copper(II) oxide (⩾3 phr) could slightly increase the degree of crosslinking in all irradiated LDPE composites. This is due to the fact that higher amounts of copper(II) oxide could slightly induce the formation of free radicals in LDPE matrix. Besides, increasing irradiation doses was also found to gradually increase the gel content of LDPE composites by generating higher amounts of free radicals. As a consequence, these higher amounts of free radicals released in the LDPE matrix could significantly increase the degree of crosslinking. The addition of copper(II) oxide could reduce the tensile strength and fracture strain (elongation at break) of LDPE composites because of poorer interfacial adhesion effect between copper(II) oxide particles and LDPE matrix. Meanwhile, increasing irradiation doses on all copper(II) oxide added LDPE composites could marginally increase the tensile strength. In addition, increasing irradiation dose could enhance the thermal stability of LDPE composites by increasing the decomposition temperature. The oxidation induction time (OIT) analysis showed that, because of the crosslinking network in the copper(II) oxide added LDPE composites, oxidation reaction is much delayed.

Investigation of the interaction of copper(II) oxide and electron beam irradiation crosslinkable polyethylene

Energy Technology Data Exchange (ETDEWEB)

Bee, Soo-Tueen, E-mail: direct.beest@gmail.com [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Sin, Lee Tin, E-mail: direct.tinsin@gmail.com [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Ratnam, C.T. [Radiation Processing Technology Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor (Malaysia); Haraveen, K.J.S.; Tee, Tiam-Ting [Department of Chemical Engineering, Lee Kong Chian Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Sungai Long, Bandar Sungai Long, Cheras, 43000 Kajang, Selangor (Malaysia); Rahmat, A.R. [Department of Polymer Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia)

2015-10-01

In this study, the effects of electron beam irradiation on the properties of copper(II) oxide when added to low-density polyethylene (LDPE) blends were investigated. It was found that the addition of low loading level of copper(II) oxide (⩽2 phr) to LDPE results in significantly poorer gel content and hot set results. However, the incorporation of higher loading level of copper(II) oxide (⩾3 phr) could slightly increase the degree of crosslinking in all irradiated LDPE composites. This is due to the fact that higher amounts of copper(II) oxide could slightly induce the formation of free radicals in LDPE matrix. Besides, increasing irradiation doses was also found to gradually increase the gel content of LDPE composites by generating higher amounts of free radicals. As a consequence, these higher amounts of free radicals released in the LDPE matrix could significantly increase the degree of crosslinking. The addition of copper(II) oxide could reduce the tensile strength and fracture strain (elongation at break) of LDPE composites because of poorer interfacial adhesion effect between copper(II) oxide particles and LDPE matrix. Meanwhile, increasing irradiation doses on all copper(II) oxide added LDPE composites could marginally increase the tensile strength. In addition, increasing irradiation dose could enhance the thermal stability of LDPE composites by increasing the decomposition temperature. The oxidation induction time (OIT) analysis showed that, because of the crosslinking network in the copper(II) oxide added LDPE composites, oxidation reaction is much delayed.

Multiple Bistability in Quinonoid-Bridged Diiron(II) Complexes: Influence of Bridge Symmetry on Bistable Properties.

Science.gov (United States)

van der Meer, Margarethe; Rechkemmer, Yvonne; Breitgoff, Frauke D; Marx, Raphael; Neugebauer, Petr; Frank, Uta; van Slageren, Joris; Sarkar, Biprajit

2016-11-21

Quinonoid bridges are well-suited for generating dinuclear assemblies that might display various bistable properties. In this contribution we present two diiron(II) complexes where the iron(II) centers are either bridged by the doubly deprotonated form of a symmetrically substituted quinonoid bridge, 2,5-bis[4-(isopropyl)anilino]-1,4-benzoquinone (H 2 L2') with a [O,N,O,N] donor set, or with the doubly deprotonated form of an unsymmetrically substituted quinonoid bridge, 2-[4-(isopropyl)anilino]-5-hydroxy-1,4-benzoquinone (H 2 L5') with a [O,O,O,N] donor set. Both complexes display temperature-induced spin crossover (SCO). The nature of the SCO is strongly dependent on the bridging ligand, with only the complex with the [O,O,O,N] donor set displaying a prominent hysteresis loop of about 55 K. Importantly, only the latter complex also shows a pronounced light-induced spin state change. Furthermore, both complexes can be oxidized to the mixed-valent iron(II)-iron(III) form, and the nature of the bridge determines the Robin and Day classification of these forms. Both complexes have been probed by a battery of electrochemical, spectroscopic, and magnetic methods, and this combined approach is used to shed light on the electronic structures of the complexes and on bistability. The results presented here thus show the potential of using the relatively new class of unsymmetrically substituted bridging quinonoid ligands for generating intriguing bistable properties and for performing site-specific magnetic switching.

Bifunctional Zn(II)Ln(III) dinuclear complexes combining field induced SMM behavior and luminescence: enhanced NIR lanthanide emission by 9-anthracene carboxylate bridging ligands.

Science.gov (United States)

Palacios, María A; Titos-Padilla, Silvia; Ruiz, José; Herrera, Juan Manuel; Pope, Simon J A; Brechin, Euan K; Colacio, Enrique

2014-02-03

There were new dinuclear Zn(II)-Ln(III) complexes of general formulas [Zn(μ-L)(μ-OAc)Ln(NO3)2] (Ln(III) = Tb (1), Dy (2), Er (3), and Yb (4)), [Zn(μ-L)(μ-NO3)Er(NO3)2] (5), [Zn(H2O)(μ-L)Nd(NO3)3]·2CH3OH (6), [Zn(μ-L)(μ-9-An)Ln(NO3)2]·2CH3CN (Ln(III) = Tb (7), Dy (8), Er (9), Yb(10)), [Zn(μ-L)(μ-9-An)Yb(9-An)(NO3)3]·3CH3CN (11), [Zn(μ-L)(μ-9-An)Nd(9-An)(NO3)3]·2CH3CN·3H2O (12), and [Zn(μ-L)(μ-9-An)Nd(CH3OH)2(NO3)]ClO4·2CH3OH (13) prepared from the reaction of the compartmental ligand N,N',N″-trimethyl-N,N″-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L), with ZnX2·nH2O (X = NO3(-) or OAc(-)) salts, Ln(NO3)3·nH2O, and, in some instances, 9-anthracenecarboxylate anion (9-An). In all these complexes, the Zn(II) ions invariably occupy the internal N3O2 site whereas the Ln(III) ions show preference for the O4 external site, giving rise to a Zn(μ-diphenoxo)Ln bridging fragment. Depending on the Zn(II) salt and solvent used in the reaction, a third bridge can connect the Zn(II) and Ln(III) metal ions, giving rise to triple-bridged diphenoxoacetate in complexes 1-4, diphenoxonitrate in complex 5, and diphenoxo(9-anthracenecarboxylate) in complexes 8-13. Dy(III) and Er(III) complexes 2, 8 and 3, 5, respectively, exhibit field induced single molecule magnet (SMM) behavior, with Ueff values ranging from 11.7 (3) to 41(2) K. Additionally, the solid-state photophysical properties of these complexes are presented showing that ligand L(2-) is able to sensitize Tb(III)- and Dy(III)-based luminescence in the visible region through an energy transfer process (antenna effect). The efficiency of this process is much lower when NIR emitters such as Er(III), Nd(III), and Yb(III) are considered. When the luminophore 9-anthracene carboxylate is incorporated into these complexes, the NIR luminescence is enhanced which proves the efficiency of this bridging ligand to act as antenna group. Complexes 2, 3, 5, and 8 can be considered as dual materials

Two hybrids based on Keggin polyoxometalates and dinuclear ...

Indian Academy of Sciences (India)

YAN HOU

2017-10-13

Oct 13, 2017 ... obtained in identical hydrothermal conditions and further characterized by elemental analyses, ... oxalate-bipyridine cationic complexes and copper(II)- ... ethylenediamine and ox = oxalic acid anion) have been obtained.

Magnetic interactions in oxide-bridged dichromium(III) complexes. Computational determination of the importance of non-bridging ligands

DEFF Research Database (Denmark)

Morsing, Thorbjørn Juul; Sauer, Stephan P. A.; Weihe, Høgni

2013-01-01

The magnetic susceptibility of the dinuclear chromium(III) complex [(CH3CN)5CrOCr(NCCH3)5](BF4)4 · 2 CH3CN has been measured and analyzed. With a fitted value of the triplet energy J = 650 cm-1, the antiferromagnetic coupling is the strongest hitherto determined for an unsupported linear oxide-br...... relative errors typically of less than 10 % ranging from the strongest coupled systems to systems with moderately strong couplings. A significant influence (>20%) of the chemical nature of the peripheral, non-bridging ligands on the exchange coupling was found and rationalized....

XAFS Study of the Ferro- and Antiferromagnetic Binuclear Copper(II) Complexes of Azomethine Based Tridentate Ligands

International Nuclear Information System (INIS)

Vlasenko, Valery G.; Vasilchenko, Igor S.; Shestakova, Tatiana E.; Uraev, Ali I.; Burlov, Anatolii S.; Garnovskii, Alexander D.; Pirog, Irina V.

2007-01-01

Binuclear copper complexes are known to be models for metalloenzymes containing copper active sites, and some of them are of considerable interest due to their magnetic and charge transfer properties. The reactions of the complex formation of bibasic tridentate heterocyclic imines with copper acetate leads to two types of chelates with mono deprotonated ligands and with totally deprotonated ligands. Cu K-edge EXAFS has been applied to determine the local structure around the metal center in copper(II) azomethine complexes with five tridentate ligands: 1-(salycilideneimino)- or 1-(2-tosylaminobenzilideneimino)-2-amino(oxo, thio)benzimidazoles. It has been found that some of the chelates studied are bridged binuclear copper complexes, and others are mononuclear complexes. The copper-copper interatomic distances in the bridged binuclear copper complexes were found to be 2.85-3.01 A. Variable temperature magnetic susceptibility data indicate the presence of both ferromagnetic and antiferromagnetic interactions within the dimer, the former is dominating at low temperatures and the latter at high temperatures

Formation of a dinuclear complex in collisions between light nuclei and entrance channel limitations to fusion

International Nuclear Information System (INIS)

Shapira, D.; Shivakumar, B.; Ayik, S.; Harmon, B.A.

1986-01-01

A model for fusion of light nuclei has been proposed recently wherein fusion progresses through nucleus-nucleus capture via a dinuclear stage which acts as a doorway to fusion. While this model accounts for the fusion cross sections, it makes no attempt at predicting observables associated with the non-fusion part of the captured flux. A study of products from the decay of the dinuclear complex into non-fusion channels can provide a stringent test for such a model. In this contribution a model which addresses both the binary decay and the fusion of a dinuclear complex formed in the collision is described and model predictions are compared with data. Accompanying contributions discuss the formalism which is used to describe the evolution of the dinuclear complex and present new data which provide information that helps justify the approximations made in applying this model

Electrochemical chiral recognition by microparticle coatings of Pd complexes with bridging cyclometalated phosphines

Energy Technology Data Exchange (ETDEWEB)

Domenech, Antonio [Departament de Quimica Analitica, Facultat de Quimica, Universitat de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia (Spain)], E-mail: antonio.domenech@uv.es; Koshevoy, Igor O.; Penno, Dirk; Ubeda, Maria Angeles [Departament de Quimica Inorganica, Facultat de Quimica, Universitat de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia (Spain)

2008-03-10

The palladium(II) dinuclear complex with bridging cyclometalated phosphines, {l_brace}Pd{sub 2}[{mu}-(C{sub 6}H{sub 4})PPh{sub 2}]{sub 2}({mu}-O{sub 2}CCH{sub 3}){sub 2}{r_brace} (Pd{sub 2}L{sub 2}), having a paddlewheel structure, is reversibly oxidized in CH{sub 2}Cl{sub 2} to a dinuclear palladium(III) analogue via two successive one-electron steps. Solid state voltammetry of Pd{sub 2}L{sub 2} in contact with aqueous electrolytes produce as one-electron oxidation with two competing mechanisms involving anion intercalation/anion binding between/to metal centres, chloride ions acting as inhibitors for the first pathway. R- and S-Pd{sub 2}L{sub 2} produces a significant stereoselective electrocatalytic activity with respect to the oxidation of L- and D-glutamic acid in alkaline media.

Synthesis, crystal structure and luminescent properties of lanthanide extended structure with asymmetrical dinuclear units based on 2-(methylthio)benzoic acid

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Cristiane K.; Souza, Viviane P. de; Luz, Leonis L. da [Departamento de Química Fundamental, UFPE, 50.740-560 Recife, PE (Brazil); Menezes Vicenti, Juliano R. de [Escola de Química e Alimento, FURG, 96203-900 Rio Grande, RS (Brazil); Burrow, Robert A. [Departamento de Química, UFSM, 97105-900 Santa Maria, RS (Brazil); Severino Alves; Longo, Ricardo L. [Departamento de Química Fundamental, UFPE, 50.740-560 Recife, PE (Brazil); Malvestiti, Ivani, E-mail: ivani@ufpe.br [Departamento de Química Fundamental, UFPE, 50.740-560 Recife, PE (Brazil)

2016-02-15

The extended structures [Ln{sub 2}(L){sub 6}(OH{sub 2}){sub 4}] with L=2-(methylthio)benzoato (2-CH{sub 3}S–C{sub 6}H{sub 4}COO{sup −}) and Ln=Tb (1), Eu (2) and Gd (3) were successfully synthesized and characterized. The single crystal structure of compound 1 was determined and showed an extended structure made up of asymmetrical dinuclear units with the formula catena-poly[{Tb(H_2O)_4}-(μ-L-1κO:2κO'){sub 2}-{Tb(L-κO,O')_2}-(μ-L-1κO:2κO'){sub 2}]. In the molecule of 1, there are two distinct metal sites. The Tb atom in site 1 is bound to four coordinated water molecules and four oxygen atoms from four different benzoate ligands, two of which bridge to site 2 Tb atoms on one side and two to site 2 Tb atoms on the other side. The site 2 Tb atom is bound to four oxygen atoms from two chelating benzoate ligands and four oxygen atoms from four different benzoate ligands, two of which bridge to site 1 Tb atoms on one side and two to site 1 Tb atoms on the other side. The bridging benzoate ligands extend the framework in one-dimension with alternating site 1/site 2 Tb atoms. The luminescent properties of these asymmetric dinuclear extended structures are quite peculiar and showed a single emitting lanthanide center. The quantum yields of 1 (ca. 50–55%) is practically independent of the excitation energy, whereas those of 2 are vanishing small (<1%) when excited at the ligand states and become sizable (ca. 10–20%) upon excitation at the intra-4f manifold. To reconcile these experimental observations in conjunction with the spectral data for compounds 1 and 3, a strong interaction between the lanthanide emitting states at sites 1 and 2 was proposed. For compound 1, the numerical solutions of the rate equations provided evidences that when the transition rates between the emitting states at both sites are larger than the highest decaying rate of these states, the system becomes an effective single emitter. This establishes, for the first time

Mechanism of Water Oxidation Catalyzed by a Dinuclear Ruthenium Complex Bridged by Anthraquinone

Directory of Open Access Journals (Sweden)

Tohru Wada

2017-02-01

Full Text Available We synthesized 1,8-bis(2,2′:6′,2″-terpyrid-4′-ylanthraquinone (btpyaq as a new dimerizing ligand and determined its single crystal structure by X-ray analysis. The dinuclear Ruthenium complex [Ru2(µ-Cl(bpy2(btpyaq](BF43 ([3](BF43, bpy = 2,2′-bipyridine was used as a catalyst for water oxidation to oxygen with (NH42[Ce(NO36] as the oxidant (turnover numbers = 248. The initial reaction rate of oxygen evolution was directly proportional to the concentration of the catalyst and independent of the oxidant concentration. The cyclic voltammogram of [3](BF43 in water at pH 1.3 showed an irreversible catalytic current above +1.6 V (vs. SCE, with two quasi-reversible waves and one irreversible wave at E1/2 = +0.62, +0.82 V, and Epa = +1.13 V, respectively. UV-vis and Raman spectra of [3](BF43 with controlled-potential electrolysis at +1.40 V revealed that [Ru(IV=O O=Ru(IV]4+ is stable under electrolysis conditions. [Ru(III, Ru(II] species are recovered after dissociation of an oxygen molecule from the active species in the catalytic cycle. These results clearly indicate that an O–O bond is formed via [Ru(V=O O=Ru(IV]5+.

Interpretation of the mechanism of spontaneous fission of heavy nuclei in the framework of dinuclear system conception

International Nuclear Information System (INIS)

Volkov, V.V.; Cherepanov, E.A.; Kalandarov, Sh.A.

2016-01-01

A new approach to the interpretation of the process of spontaneous fission of heavy nuclei is suggested. It is based on nuclear physics data which are obtained in heavy ion collisions. The process of spontaneous fission consists of three sequential stages: clusterization of the valent nucleons of a heavy nucleus into a light nucleus-cluster, which leads to the formation of a dinuclear system; evolution of the dinuclear system which proceeds by nucleon transfer from the heavy to light nucleus; and decay of the dinuclear system from the equilibrium configuration into two fragments. [ru

Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

KAUST Repository

Anderson, Carly E.; Vagin, Sergei I.; Hammann, Markus; Zimmermann, Leander; Rieger, Bernhard

2013-01-01

Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Copolymerisation of Propylene Oxide and Carbon Dioxide by Dinuclear Cobalt Porphyrins

KAUST Repository

Anderson, Carly E.

2013-09-18

Two dinuclear cobalt porphyrins comprising different structural tethering motifs at the porphyrin periphery were synthesised, along with a representative mononuclear cobalt porphyrin, and their catalytic activities tested towards carbon dioxide-propylene oxide copolymerisation in the presence of bis(triphenylphosphoranyl)ammonium chloride cocatalyst. The catalytic activities of the mononuclear and the bis-para-tethered dinuclear cobalt porphyrin with selective formation of poly(propylene carbonate) are largely comparable, showing no benefit of dinuclearity in contrast to the case of cobalt salen complexes and suggesting that polymer growth proceeds exclusively from one metal centre. The alternative bis-ortho-tethered porphyrin demonstrated considerably reduced activity, with dominant formation of cyclic propylene carbonate, as a result of hindered substrate approach at the metal centre. Time-resolved UV/Vis spectroscopic studies suggested a general intolerance of the cobalt(III) porphyrin catalysts towards the copolymerisation conditions in the absence of carbon dioxide pressure, leading to catalytically inactive cobalt(II) species. In the presence of carbon dioxide, the bis-ortho-tethered catalyst showed the fastest deactivation, which is related to an unfavourable steric arrangement of the linker fragment, as was also confirmed by NMR spectroscopic measurements. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Syntheses, structures, and properties of imidazolate-bridged Cu(II)-Cu(II) and Cu(II)-Zn(II) dinuclear complexes of a single macrocyclic ligand with two hydroxyethyl pendants.

Science.gov (United States)

Li, Dongfeng; Li, Shuan; Yang, Dexi; Yu, Jiuhong; Huang, Jin; Li, Yizhi; Tang, Wenxia

2003-09-22

The imidazolate-bridged homodinuclear Cu(II)-Cu(II) complex, [(CuimCu)L]ClO(4).0.5H(2)O (1), and heterodinuclear Cu(II)-Zn(II) complex, [(CuimZnL(-)(2H))(CuimZnL(-)(H))](ClO(4))(3) (2), of a single macrocyclic ligand with two hydroxyethyl pendants, L (L = 3,6,9,16,19,22-hexaaza-6,19-bis(2-hydroxyethyl)tricyclo[22,2,2,2(11,14)]triaconta-1,11,13,24,27,29-hexaene), have been synthesized as possible models for copper-zinc superoxide dismutase (Cu(2),Zn(2)-SOD). Their crystal structures analyzed by X-ray diffraction methods have shown that the structures of the two complexes are markedly different. Complex 1 crystallizes in the orthorhombic system, containing an imidazolate-bridged dicopper(II) [Cu-im-Cu](3+) core, in which the two copper(II) ions are pentacoordinated by virtue of an N4O environment with a Cu.Cu distance of 5.999(2) A, adopting the geometry of distorted trigonal bipyramid and tetragonal pyramid, respectively. Complex 2 crystallizes in the triclinic system, containing two similar Cu-im-Zn cores in the asymmetric unit, in which both the Cu(II) and Zn(II) ions are pentacoordinated in a distorted trigonal bipyramid geometry, with the Cu.Zn distance of 5.950(1)/5.939(1) A, respectively. Interestingly, the macrocyclic ligand with two arms possesses a chairlike (anti) conformation in complex 1, but a boatlike (syn) conformation in complex 2. Magnetic measurements and ESR spectroscopy of complex 1 have revealed the presence of an antiferromagnetic exchange interaction between the two Cu(II) ions. The ESR spectrum of the Cu(II)-Zn(II) heterodinuclear complex 2 displayed a typical signal for mononuclear trigonal bipyramidal Cu(II) complexes. From pH-dependent ESR and electronic spectroscopic studies, the imidazolate bridges in the two complexes have been found to be stable over broad pH ranges. The cyclic voltammograms of the two complexes have been investigated. Both of the two complexes can catalyze the dismutation of superoxide and show rather high activity.

The controlled formation and cleavage of an intramolecular d8-d8 Pt-Pt interaction in a dinuclear cycloplatinated molecular "pivot-hinge".

Science.gov (United States)

Koo, Chi-Kin; Wong, Ka-Leung; Lau, Kai-Cheung; Wong, Wai-Yeung; Lam, Michael Hon-Wah

2009-08-03

The bis(diphenylphosphino)methane (dppm)-bridged dinuclear cycloplatinated complex {[Pt(L)](2)(mu-dppm)}(2+) (Pt(2)dppm; HL: 2-phenyl-6-(1H-pyrazol-3-yl)-pyridine) demonstrates interesting reversible "pivot-hinge"-like intramolecular motions in response to the protonation/deprotonation of L. In its protonated "closed" configuration, the two platinum(II) centers are held in position by intramolecular d(8)-d(8) Pt-Pt interaction. In its deprotonated "open" configuration, such Pt-Pt interaction is cleaved. To further understand the mechanism behind this hingelike motion, an analogous dinuclear cycloplatinated complex, {[Pt(L)](2)(mu-dchpm)}(2+) (Pt(2)dchpm) with bis(dicyclohexylphosphino)methane (dchpm) as the bridging ligand, was synthesized. From its protonation/deprotonation responses, it was revealed that aromatic pi-pi interactions between the phenyl moieties of the mu-dppm and the deprotonated pyrazolyl rings of L was essential to the reversible cleavage of the intramolecular Pt-Pt interaction in Pt(2)dppm. In the case of Pt(2)dchpm, spectroscopic and spectrofluorometric titrations as well as X-ray crystallography indicated that the distance between the two platinum(II) centers shrank upon deprotonation, thus causing a redshift in its room-temperature triplet metal-metal-to-ligand charge-transfer emission from 614 to 625 nm. Ab initio calculations revealed the presence of intramolecular hydrogen bonding between the deprotonated and negatively charged 1-pyrazolyl-N moiety and the methylene CH and phenyl C-H of the mu-dppm. The "open" configuration of the deprotonated Pt(2)dppm was estimated to be 19 kcal mol(-1) more stable than its alternative "closed" configuration. On the other hand, the open configuration of the deprotonated Pt(2)dchpm was 6 kcal mol(-1) less stable than its alternative closed configuration.

PREDICCIÓN DE LA ESTRUCTURA Y CARACTERÍSTICAS BIOQUÍMICAS DE LA ACETATO TIOQUINASA

Directory of Open Access Journals (Sweden)

Jairo A. Tovart

2001-12-01

Full Text Available Las actividades de las enzimas implicadas en el metabolismo de los cuerpos cetónicos están presentes tanto en neuronas, como en astrocitos y en oligodendroglía. La utilización de cultivos primarios ha puesto de manifiesto que estos cuerpos cetónicos pueden ser metabolizados en estas células.La· acetato tioquinasa reportada en tejido neural total es una enzima que reduce significativamente el costo energético de la utilización del acetato y por lo tanto se propone como una ruta de elección en metabolismo de esta sustancia.Los datos de predicción para propiedades bioquímicas y estructurales de la enzima muestran una estructura estable, con segmentos conservados entre todas las secuencias existentes y una alta flexibilidad estructural, propia de la mayoría de la enzimas.

Biosorption of copper(II) and lead(II) onto potassium hydroxide treated pine cone powder.

Science.gov (United States)

Ofomaja, A E; Naidoo, E B; Modise, S J

2010-08-01

Pine cone powder surface was treated with potassium hydroxide and applied for copper(II) and lead(II) removal from solution. Isotherm experiments and desorption tests were conducted and kinetic analysis was performed with increasing temperatures. As solution pH increased, the biosorption capacity and the change in hydrogen ion concentration in solution increased. The change in hydrogen ion concentration for lead(II) biosorption was slightly higher than for copper(II) biosorption. The results revealed that ion-exchange is the main mechanism for biosorption for both metal ions. The pseudo-first order kinetic model was unable to describe the biosorption process throughout the effective biosorption period while the modified pseudo-first order kinetics gave a better fit but could not predict the experimentally observed equilibrium capacities. The pseudo-second order kinetics gave a better fit to the experimental data over the temperature range from 291 to 347 K and the equilibrium capacity increased from 15.73 to 19.22 mg g(-1) for copper(II) and from 23.74 to 26.27 for lead(II). Activation energy was higher for lead(II) (22.40 kJ mol(-1)) than for copper(II) (20.36 kJ mol(-1)). The free energy of activation was higher for lead(II) than for copper(II) and the values of DeltaH* and DeltaS* indicate that the contribution of reorientation to the activation stage is higher for lead(II) than copper(II). This implies that lead(II) biosorption is more spontaneous than copper(II) biosorption. Equilibrium studies showed that the Langmuir isotherm gave a better fit for the equilibrium data indicating monolayer coverage of the biosorbent surface. There was only a small interaction between metal ions when simultaneously biosorbed and cation competition was higher for the Cu-Pb system than for the Pb-Cu system. Desorption studies and the Dubinin-Radushkevich isotherm and energy parameter, E, also support the ion-exchange mechanism. Copyright 2010 Elsevier Ltd. All rights reserved.

Enhanced reactivity of dinuclear Copper(I) acetylides in dipolar cycloadditions

DEFF Research Database (Denmark)

Ahlquist, Mårten Sten Gösta; Fokin, V.V.

2007-01-01

Dinuclear alkynyl copper(I) complexes exhibit superior reactivity toward organic azides compared to their monomeric analogues. DFT studies indicate that the second copper center facilitates the formation of the cupracycle in the rate-determining step and stabilizes the metallacycle intermediate i...

Synthesis, Characterization and DNA Cleavage of Copper(II ...

African Journals Online (AJOL)

Keywords: DNA shearing, Copper(II) complex, Dithiothreitol, Attenuated total reflectance-Fourier transform .... confirm the fragmentation of DNA by the newly .... sperm. Biochem Biophys Acta 1986; 884: 124-134. 7. Cornell NW, Crivaro KE.

Dinuclear Cu(II) complexes of isomeric bis-(3-acetylacetonate)benzene ligands: synthesis, structure, and magnetic properties.

Science.gov (United States)

Rancan, Marzio; Dolmella, Alessandro; Seraglia, Roberta; Orlandi, Simonetta; Quici, Silvio; Sorace, Lorenzo; Gatteschi, Dante; Armelao, Lidia

2012-05-07

Highly versatile coordinating ligands are designed and synthesized with two β-diketonate groups linked at the carbon 3 through a phenyl ring. The rigid aromatic spacer is introduced in the molecules to orient the two acetylacetone units along different angles and coordination vectors. The resulting para, meta, and ortho bis-(3-acetylacetonate)benzene ligands show efficient chelating properties toward Cu(II) ions. In the presence of 2,2'-bipyridine, they promptly react and yield three dimers, 1, 2, and 3, with the bis-acetylacetonate unit in bridging position between two metal centers. X-ray single crystal diffraction shows that the compounds form supramolecular chains in the solid state because of intermolecular interactions. Each of the dinuclear complexes shows a magnetic behavior which is determined by the combination of structural parameters and spin polarization effects. Notably, the para derivative (1) displays a moderate antiferromagnetic coupling (J = -3.3 cm(-1)) along a remarkably long Cu···Cu distance (12.30 Å).

The ligational behavior of an isatinic quinolyl hydrazone towards copper(II- ions

Directory of Open Access Journals (Sweden)

Mousa Marwa A

2011-04-01

Full Text Available Abstract Background The importance of the isatinic quinolyl hydrazones arises from incorporating the quinoline ring with the indole ring. Quinoline ring has therapeutic and biological activities whereas, the indole ring occurs in Jasmine flowers and Orange blossoms. As a ligand, the isatin moiety is potentially ambidentate and can coordinate the metal ions either through its lactam or lactim forms. In a previous study, the ligational behavior of a phenolic quinolyl hydrazone towards copper(II- ions has been studied. As continuation of our interest, the present study is planned to check the ligational behavior of an isatinic quinolyl hydrazone. Results New homo- and heteroleptic copper(II- complexes were obtained from the reaction of an isatinic quinolyl hydrazone (HL with several copper(II- salts viz. Clˉ, Brˉ, NO3ˉ, ClO4-, SO42- and AcO-. The obtained complexes have Oh, Td and D4h- symmetry and fulfill the strong coordinating ability of Clˉ, Brˉ, NO3ˉ and SO42- anions. Depending on the type of the anion, the ligand coordinates the copper(II- ions either through its lactam (NO3ˉ and ClO4- or lactim (the others forms. Conclusion The effect of anion for the same metal ion is obvious from either the geometry of the isolated complexes (Oh, Td and D4h or the various modes of bonding. Also, the obtained complexes fulfill the strong coordinating ability of Clˉ, Brˉ, NO3ˉ and SO42- anions in consistency with the donor ability of the anions. In case of copper(II- acetate, a unique homoleptic complex (5 was obtained in which the AcO- anion acts as a base enough to quantitatively deprotonate the hydrazone. The isatinic hydrazone uses its lactim form in most complexes.

Solvothermal synthesis of uranium(VI) phases with aromatic carboxylate ligands: A dinuclear complex with 4-hydroxybenzoic acid and a 3D framework with terephthalic acid

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yingjie, E-mail: yzx@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Karatchevtseva, Inna [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Bhadbhade, Mohan [Mark Wainwright Analytical Centre, University of New South Wales, Kensington, NSW 2052 (Australia); Tran, Toan Trong; Aharonovich, Igor [School of Physics and Advanced Materials, University of Technology Sydney, Ultimo, NSW 2007 (Australia); Fanna, Daniel J.; Shepherd, Nicholas D. [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lu, Kim [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Li, Feng [School of Science and Health, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751 (Australia); Lumpkin, Gregory R. [Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

2016-02-15

With the coordination of dimethylformamide (DMF), two new uranium(VI) complexes with either 4-hydroxybenzoic acid (H{sub 2}phb) or terephthalic acid (H{sub 2}tph) have been synthesized under solvothermal conditions and structurally characterized. [(UO{sub 2}){sub 2}(Hphb){sub 2}(phb)(DMF)(H{sub 2}O){sub 3}]·4H{sub 2}O (1) has a dinuclear structure constructed with both pentagonal and hexagonal bipyramidal uranium polyhedra linked through a µ{sub 2}-bridging ligand via both chelating carboxylate arm and alcohol oxygen bonding, first observation of such a coordination mode of 4-hydroxybenzoate for 5 f ions. [(UO{sub 2})(tph)(DMF)] (2) has a three-dimensional (3D) framework built with pentagonal bipyramidal uranium polyhedra linked with µ{sub 4}-terephthalate ligands. The 3D channeled structure is facilitated by the unique carboxylate bonding with nearly linear C–O–U angles and the coordination of DMF molecules. The presence of phb ligands in different coordination modes, uranyl ions in diverse environments and DMF in complex 1, and tph ligand, DMF and uranyl ion in complex 2 has been confirmed by Raman spectroscopy. In addition, their thermal stability and photoluminescence properties have been investigated. - Graphical abstract: With the coordination of dimethylformamide, two new uranyl complexes with either 4-hydroxybenzoate or terephthalate have been synthesized under solvothermal conditions and structurally characterized. - Highlights: • Solvent facilitates the synthesis of two new uranium(VI) complexes. • A dinuclear complex with both penta- and hexagonal bipyramidal uranium polyhedral. • A unique µ{sub 2}-bridging mode of 4-hydroxybenzoate via alcohol oxygen for 5 f ions. • A 3D framework with uranium polyhedra and µ{sub 4}-terephthalate ligands. • Vibration modes and photoluminescence properties are reported.

Filme ativo de acetato de celulose incorporado com nanosuspensão de curcumina

Directory of Open Access Journals (Sweden)

Deivis de Moraes Carvalho

Full Text Available Resumo As embalagens ativas podem liberar substâncias para inibir a microbiota e as reações na superfície dos alimentos. Dentre essas substâncias a curcumina pode ser usada pois apresenta atividade antimicrobiana e antioxidante. A difusão de compostos ativos em filmes de acetato de celulose pode ser estendida por longos períodos a taxa controlada. Sua adição pode afetar as propriedades mecânicas e de barreira dos filmes, tornando-se necessário mensurar estas alterações. Assim, objetivou-se preparar filmes ativos de acetato de celulose e tween 80 incorporados com mistura simples de curcumina e nanosuspensão de curcumina e avaliar cor, propriedades mecânicas, permeabilidade ao CO2 e migração do componente ativo. A curcumina influenciou as características mecânicas, ópticas e não afetou a permeabilidade dos filmes. O tween 80 favoreceu a migração da curcumina e a redução do tamanho das partículas não aumentou a migração de curcumina.

Evaluación del efecto tóxico del acetato plomo y el cloruro de cromo sobre el metabolismo bacterial anaerobio

Directory of Open Access Journals (Sweden)

Beatriz Wills

2004-01-01

Full Text Available Se presentan los resultados del estudio de toxicidad del cloruro de cromo (CrCl3 y el acetato de plomo (CH3COO2Pb del lodo de un reactor anaerobio de flujo ascendente y manto de lodos (UASB, aclimatado y estabilizado en el laboratorio con una solución de suero en polvo sintético; los ensayos de toxicidad se realizaron en botellas serológicas de 60 mL, se utilizaron como sustratos soluciones de ácido fórmico y suero en polvo sintético y se ensayaron concentraciones de cloruro de cromo en el rango de 1.000 a 5.000 mg/L, y de 1.000 a 10.000 mg/L para el acetato de plomo. Durante 72 horas se valoró la producción de metano en mL y el comportamiento del potencial redox en mV.Se presentaron reducciones del 50% en la producción de metano a concentraciones de 3.322 mg/L para cloruro de cromo y 1.415 mg/L para el acetato de plomo cuando el sustrato fue ácido fórmico, y a 2.291 mg/L para el cloruro de cromo y 1.982 mg/L para el acetato de plomo cuando el sustrato fue suero en polvo sintético.En síntesis, el artículo demuestra que las bacterias metanogénicas tienen un grado de resistencia cuantificable con respecto a las diferentes concentraciones de metales aplicados

Interactions between copper(II) and DOM in the urban stormwater runoff: modeling and characterizations.

Science.gov (United States)

Zhao, Chen; Wang, Chong-Chen; Li, Jun-Qi; Wang, Peng; Ou, Jia-Qi; Cui, Jing-Rui

2018-01-01

Dissolved organic matter (DOM) can strongly interact with both organic and inorganic contaminants to influence their transportation, transformation, bioavailability, toxicity and even their ultimate fate. Within this work, DOM was extracted from urban stormwater runoff samples collected from a regular sampling site of a typical residential area in Beijing, China. Copper(II) ions were selected as model to investigate the interactions between DOM and typical heavy metals. Both ultraviolet (UV) absorbance and fluorescence titration methods were introduced to determine the complex capacities (C L ) and conditional stability constants (log K M ) of bonding between DOM and copper (II) ions, which revealed that the values of C L were 85.62 and 87.23 μmol mg -1 and the log K M values were 5.37 and 5.48, respectively. The results suggested the successful complexation between DOM and copper(II) ions. Furthermore, morphology of the DOM binding to copper(II) ions was confirmed by both energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS), which can facilitate to clarify the corresponding mechanism. The Cu 2p 3/2 peak at 933.7 eV and the characteristic shake-up peaks of Cu-O were found in the XPS spectra, implying that copper(II) ions might coordinate with hydroxyl (aliphatic or phenolic) or carboxyl groups. With these profitable results, it can be concluded that DOM in urban stormwater runoff has a strong binding affinity with copper(II) ions, which may further lead to potentially significant influence on their migration and transformation.

Syntheses and a Solid State Structure of a Dinuclear Molybdenum(V Complex with Pyridine

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Jon Zubieta

2010-01-01

Full Text Available A mononuclear complex [MoOCl4(H2O]− readily forms a metal−metal bonded {Mo2O4}2+ core. A high content of pyridine in the reaction mixture prevents further aggregation of dinuclear cores into larger clusters and a neutral, dinuclear complex with the [Mo2O4Cl2(Py4] composition is isolated as a product. Solid state structures of two compounds containing this complex, [Mo2O4Cl2(Py4]·2.25Py (1 and [Mo2O4Cl2(Py4]·1.5PyHCl (2, were investigated by X-ray crystallography.

Centrifugal Fragmentation of a Dinuclear System in the Process of Its Evolution to the Compound Nucleus

CERN Document Server

Volkov, V V

2005-01-01

The physical content of centrifugal fragmentation is discussed. It is a specific nuclear process which is realized in the evolution of a dinuclear system into a compound nucleus at large angular momenta and large mass asymmetry of the system. The dinuclear system concept which describes the process of the compound nucleus formation in heavy ion reactions predicts the possibility of centrifugal fragmentation. Experimental data giving evidence of the realization of this nuclear process are given. A possible scheme of the centrifugal fragmentation model is discussed.

Centrifugal fragmentation of a dinuclear system in the process of its evolution to the compound nucleus

International Nuclear Information System (INIS)

Volkov, V.V.

2005-01-01

The physical content of centrifugal fragmentation is discussed. It is a specific nuclear process which is realized in the evolution of a dinuclear system into a compound nucleus at large angular momenta and large mass asymmetry of the system. The dinuclear system concept which describes the process of the compound nucleus formation in heavy ion reactions predicts the possibility of centrifugal fragmentation. Experimental data giving evidence of the realization of this nuclear process are given. A possible scheme of the centrifugal fragmentation model is discussed

Preconcentration and extraction of copper(II) on activated carbon ...

African Journals Online (AJOL)

Activated carbon modified method was used for the preconcentration and ... in real samples such as tap water, wastewater and a synthetic water sample by flame ... KEY WORDS: Copper(II), Solid phase extraction, Activated carbon, Flame ...

Study of the interaction mechanism in the biosorption of copper(II) ions onto posidonia oceanica and peat

Energy Technology Data Exchange (ETDEWEB)

Izquierdo, Marta; Marzal, Paula; Gabaldon, Carmen [Departamento de Ingenieria Quimica, Escuela Tecnica Superior de Ingenieria, Universitat de Valencia, Valencia (Spain); Silvetti, Margherita; Castaldi, Paola [Dipartimento di Scienze Ambientali e Agrarie e Biotecnologie Agro-Alimentari, Sez. Chimica Agraria ed Ambientale, University of Sassari, Sassari (Italy)

2012-04-15

A systematic approach was used to characterize the biosorption of copper(II) onto two biosorbents, Posidonia oceanica and peat, focusing on the interaction mechanisms, the copper(II) sorption-desorption process and the thermal behavior of the biosorbents. Sorption isotherms at pH 4-6 were obtained and the experimental data were fitted to the Langmuir model with a maximum uptake (q{sub max}) at pH 6 of 85.78 and 49.69 mg g{sup -1}, for P. oceanica and peat, respectively. A sequential desorption (SD) with water, Ca(NO{sub 3}){sub 2}, and EDTA was applied to copper-saturated biosorbents. Around 65-70% copper(II) were desorbed with EDTA, indicating that this heavy metal was strongly bound. The reversibility of copper(II) sorption was obtained by desorption with HCl and SD. Fourier transform IR spectroscopy (FTIR) analysis detected the presence of peaks associated with OH groups in aromatic and aliphatic structures, CH, CH{sub 2}, and CH{sub 3} in aliphatic structures, COO{sup -} and COOH groups and unsaturated aromatic structures on the surface of both biosorbents, as well as peaks corresponding to Si-O groups on the surface of peat. The results of SEM-EDX and FTIR analysis of copper-saturated samples demonstrated that ion exchange was one of the mechanisms involved in copper(II) retention. Thermal analysis of biosorbent samples showed that copper(II) sorption-desorption processes affected the thermal stability of the biosorbents. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Tratamiento de la anorexia urémica con acetato de megestrol

OpenAIRE

Fernández Lucas, M.; Teruel, J.L.; Burguera, V.; Sosa, H.; Rivera, M.; Rodríguez Palomares, J.R.; Marcén, R.; Quereda, C.

2010-01-01

Introducción: La anorexia es un trastorno frecuente en el enfermo tratado con hemodiálisis periódica, y factor contribuyente de la malnutrición. El objetivo del presente trabajo es comprobar la eficacia del acetato de megestrol, un estimulador del apetito utilizado en enfermos con cáncer, como tratamiento de la anorexia del enfermo sometido a diálisis. Material y métodos: En el año 2009, 16 enfermos de nuestra unidad de hemodiálisis, tres de ellos con diabetes mellitus, fueron tratados con ac...

Synthesis and magnetic Properties of dinuclear oxovanadium(IV) complexes bridged by tetracarboxylato groups

International Nuclear Information System (INIS)

Li, Y.-T.; Guan, H.-S.; Yan, C.-W.

2004-01-01

Three novel μ-tetracarboxylato-bridged oxovanadium(IV) complexes described by the overall formula [(VO) 2 (PMTA)L 2 ] where PMTA stands for the tetraanion of pyromellitic acid, and L denotes 2,2'-bipyridine(bpy), 4,4'-dimethyl-2,2'-bipyridine (Me 2 bpy) or 1,10-phenanthroline (phen), respectively, have been synthesized and characterized by elemental analyses, molar conductivity and room-temperature magnetic moment measurements, IR, ESR, and electronic spectral studies. It is proposed that these complexes have PMTA-bridged structures and consist of two oxovanadium(IV) ions, each in the square-pyramidal environment. The [(VO) 2 (PMTA)(bpy) 2 ] (1) and [(VO) 2 (PMTA)(phen) 2 ] (2) complexes were further characterized by variable temperature (4.2 - 300 K) magnetic susceptibility measurements and the observed data were fitted to the modified Bleaney-Bowers equation by the least-squares, giving the exchange integral J = -2.75 cm -1 for (1) and J -3.91 cm -1 for (2). This results indicates that there is a weak antiferromagnetic spin-exchange interaction between the two VO 2+ ions within each molecule. (author)

Spectroscopic studies of Eu(III) Keggin's and Dawson's polyoxotungstates substituted by acetato and oxalato ligands

International Nuclear Information System (INIS)

But, Slawomir; Lis, Stefan

2008-01-01

Eu(III) Keggin's and Dawson's type of polyoxometalates (POM) complexes were synthesized and spectroscopically characterized. This work presents results obtained for chosen hybrids of acetato K 12 [{Eu(SiMo x W 11-x O 39 )(H 2 O)} 2 (CH 3 COO) 2 ].nH 2 O, K 16 [{Eu(CH 3 COO)(H 2 O) 2 (P 2 W 17 O 61 )} 2 ].nH 2 O and oxalato (NH 4 ) 29 K 5 [{Eu(P 2 W 17 O 61 )} 4 (C 2 O 4 ) 3 (H 2 O) 4 ].nH 2 O, where x = 0, 1. The solid state compositions of the hybrids were characterized by using elemental and ICP-AES analysis, derivatography and FTIR spectroscopy. Luminescence characteristics (intensity, quantum yields, luminescence lifetimes and excitation spectra in the range of the 5 D 0 7 F 0 transition) of the synthesized Eu(III) acetato and oxalato complexes were determined in the solid phase and in solution, and they were compared to their parent Eu(III):POM complexes of 1:1 stoichiometry (ML)

The crystal structure of paramagnetic copper(ii) oxalate (CuC2O4):

DEFF Research Database (Denmark)

Christensen, Axel Nørlund; Lebech, Bente; Andersen, Niels Hessel

2014-01-01

Synthetic copper(ii) oxalate, CuC2O4, was obtained in a precipitation reaction between a copper(ii) solution and an aqueous solution of oxalic acid. The product was identified from its conventional X-ray powder patterns which match that of the copper mineral Moolooite reported to have...... the composition CuC2O4·0.44H2O. Time resolved in situ investigations of the thermal decomposition of copper(ii) oxalate using synchrotron X-ray powder diffraction showed that in air the compound converts to Cu2O at 215 °C and oxidizes to CuO at 345 °C. Thermo gravimetric analysis performed in an inert Ar....... The crystal structure consists of a random stacking of CuC2O4 micro-crystallites where half the Cu-atoms are placed at (2a) and the other half at (2b) positions with the corresponding oxalate molecules centred around the corresponding (2b) and (2a) site positions, respectively. The diffraction patterns...

Dinuclear copper(II) complexes with {Cu2(mu-hydroxo)bis(mu-carboxylato)}+ cores and their reactions with sugar phosphate esters: A substrate binding model of fructose-1,6-bisphosphatase.

Science.gov (United States)

Kato, Merii; Tanase, Tomoaki; Mikuriya, Masahiro

2006-04-03

Reactions of CuX2.nH2O with the biscarboxylate ligand XDK (H2XDK = m-xylenediamine bis(Kemp's triacid imide)) in the presence of N-donor auxiliary ligands yielded a series of dicopper(II) complexes, [Cu2(mu-OH)(XDK)(L)2]X (L = N,N,N',N'-tetramethylethylenediamine (tetmen), X = NO3 (1a), Cl (1b); L = N,N,N'-trimethylethylenediamine (tmen), X = NO3 (2a), Cl (2b); L =2,2'-bipyridine (bpy), X = NO3 (3); L = 1,10-phenanthroline (phen), X = NO3 (4); L = 4,4'-dimethyl-2,2'-bipyridine (Me2bpy), X = NO3 (5); L = 4-methyl-1,10-phenanthroline (Mephen), X = NO3 (6)). Complexes 1-6 were characterized by X-ray crystallography (Cu...Cu = 3.1624(6)-3.2910(4) A), and the electrochemical and magnetic properties were also examined. Complexes 3 and 4 readily reacted with diphenyl phosphoric acid (HDPP) or bis(4-nitrophenyl) phosphoric acid (HBNPP) to give [Cu2(mu-phosphate)(XDK)(L)2]NO3 (L = bpy, phosphate = DPP (11); L = phen, phosphate = DPP (12), BNPP (13)), where the phsophate diester bridges the two copper ions in a mu-1,3-O,O' bidentate fashion (Cu...Cu = 4.268(3)-4.315(1) A). Complexes 4 and 6 with phen and Mephen have proven to be good precursors to accommodate a series of sugar monophosphate esters (Sugar-P) onto the biscarboxylate-bridged dicopper centers, yielding [Cu2(mu-Sugar-P)(XDK)(L)2] (Sugar-P = alpha-D-Glc-1-P (23a and b), D-Glc-6-P (24a and b), D-Man-6-P (25a), D-Fru-6-P (26a and b); L = phen (a), Mephen (b)) and [Cu2(mu-Gly-n-P)(XDK)(Mephen)2] (Gly-n-P = glycerol n-phosphate; n = 2 (21), 3 (22)), where Glc, Man, and Fru are glucose, mannose, and fructose, respectively. The structure of [Cu2(mu-MNPP)(XDK)(phen)2(CH3OH)] (20) was characterized as a reference compound (H2MNPP = 4-nitrophenyl phosphoric acid). Complexes 4 and 6 also reacted with d-fructose 1,6-bisphosphate (D-Fru-1,6-P2) to afford the tetranuclear copper(II) complexes formulated as [Cu4(mu-D-Fru-1,6-P2)(XDK)2(L)4] (L = phen (27a), Mephen (27b)). The detailed structure of 27a was determined by X

FEATURES OF INITIATION OF STYRENE POLYMERIZATION BY CUMENE HYDROPEROXIDE IN PRESENCE OF ACETULACETONATE OF COPPER(II

Directory of Open Access Journals (Sweden)

A. V. Grekova

2016-04-01

Full Text Available Kinetics of sectional styrene polymerization initiated by cumene hydroperoxide, acetylacetonate of copper(II and by the system of cumene hydroperoxide — acetylacetonate of copper(II in a temperature range 333-363 K is studied. Kinetic parameters of polymerization process are determined. It is shown, that system of cumene hydroperoxide — acetylacetonate of copper(II is in 5-6 times more effective on the initiating ability comparatively to application of its individual components. From findings ensues that decline of energy of activating of initiation from 110 kdzh/mol’ to 87 kdzh/mol’ for cumene hydroperoxide at the use of the studied system is caused with participating of monomer in preliminary complexation facilitating formation of free radicals.

Surface Structures Formed by a Copper(II Complex of Alkyl-Derivatized Indigo

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Akinori Honda

2016-10-01

Full Text Available Assembled structures of dyes have great influence on their coloring function. For example, metal ions added in the dyeing process are known to prevent fading of color. Thus, we have investigated the influence of an addition of copper(II ion on the surface structure of alkyl-derivatized indigo. Scanning tunneling microscope (STM analysis revealed that the copper(II complexes of indigo formed orderly lamellar structures on a HOPG substrate. These lamellar structures of the complexes are found to be more stable than those of alkyl-derivatized indigos alone. Furthermore, 2D chirality was observed.

Synthesis, spectroscopic and thermal studies of the copper(II) aspartame chloride complex

Science.gov (United States)

Çakır, S.; Coşkun, E.; Naumov, P.; Biçer, E.; Bulut, İ.; İçbudak, H.; Çakır, O.

2002-08-01

Aspartame adduct of copper(II) chloride Cu(Asp) 2Cl 2·2H 2O (Asp=aspartame) is synthesized and characterized by elemental analysis, FT IR, UV/vis, ESR spectroscopies, TG, DTG, DTA measurements and molecular mechanics calculations. Aqueous solution of the green solid absorbs strongly at 774 and 367 nm. According to the FT IR spectra, the aspartame moiety coordinates to the copper(II) ion via its carboxylate ends, whereas the ammonium terminal groups give rise to hydrogen bonding network with the water, the chloride ions or neighboring carboxylate groups. The results suggest tetragonally distorted octahedral environment of the copper ions.

Crystal structure of a mixed-ligand silver(I complex of the non-steroidal anti-inflammatory drug diclofenac and pyrimidine

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Sevim Hamamci Alisir

2016-10-01

Full Text Available In the title mixed-ligand silver(I coordination polymeric complex with the non-steroidal anti-inflammatory drug diclofenac (C14H11Cl2NO2 (diclH and pyrimidine (pym, namely poly[{μ2-2-[2-(2,6-dichloroanilinophenyl]acetato-κ2O:O′}(μ2-pyrimidine-κ2N1:N3silver(I], [Ag(C14H10Cl2NO2(C4H4N2]n or [Ag(μ-dicl(μ-pym]n, the very distorted tetrahedral AgN2O2 coordination centres comprise two N-atom donors from bridging pym ligands [Ag—N = 2.381 (3 and 2.412 (3 Å] and two carboxylate O-atom donors from dicl ligands [Ag—O = 2.279 (2 and 2.280 (2 Å], which bridge Ag atoms, giving a centrosymmetric dinuclear units with a short Ag...Ag separation [2.8931 (5 Å]. Within the units are short intraligand C—Cl...π(pym interactions [3.6409 (15 Å]. The units are linked through the bridging N atoms of the pym ligand into a two-dimensional sheet–polymer structure lying parallel to (100 and stabilized by inter-ring π–π interactions between the pym ligands [Cg...Cg = 3.4199 (17 Å]. Additional inter-unit C—H...O and C—H...Cg hydrogen-bonding interactions between the sheets give an overall three-dimensional structure.

RECOVERY OF COPPER(II) AND CHROMIUM(III) FROM NITRATE ...

African Journals Online (AJOL)

Guerdouh A and Barkat D

2016-05-01

May 1, 2016 ... The ionic strength of the aqueous medium was ... phases were separated completely, concentrations of the copper(II) and chromium(III) ..... [18] Huff M M, Otu E O. Solvent Extraction and Ion Exchange, 2004, 22(4), 695-712.

COPPER(II) COMPLEXES OF o -VANILLIN ACETYLHYDRAZONE ...

African Journals Online (AJOL)

A hydrazonic ligand, o-vanillin acetylhydrazone (H2L) has been prepared and used as chelating agent towards copper(II) ion. The ligand acts like a tridentate ligand in the monodeprotonated (HL-) and dideprotonated (L2-) states. Monoanionic complexes [{Cu(HL)(H2O)}2]•2BF4 and [{Cu(HL)(Hpz)(H2O)}]•NO3 have been ...

Interaction of dinuclear cadmium(II) 5-Cl-salicylaldehyde complexes with calf-thymus DNA

Energy Technology Data Exchange (ETDEWEB)

Ristovic, Maja Sumar [Department of General and Inorganic Chemistry, Faculty of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Faculty of Chemistry, University of Belgrade, Studenski Trg 12-16, Belgrade (Serbia); Zianna, Ariadni; Psomas, George; Hatzidimitriou, Antonios G. [Department of General and Inorganic Chemistry, Faculty of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Coutouli-Argyropoulou, Evdoxia [Department of Organic Chemistry and Biochemistry, Faculty of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Lalia-Kantouri, Maria, E-mail: lalia@chem.auth.gr [Department of General and Inorganic Chemistry, Faculty of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece)

2016-04-01

Five dinuclear Cd(II) complexes with the anion of 5-Cl-salicylaldehyde (5-Cl-saloH) were synthesized in the absence or presence of the α-diimines: 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (neoc) or 2,2′-dipyridylamine (dpamH) and characterized as [Cd(5-Cl-salo){sub 2}(CH{sub 3}OH)]{sub 2} (1), [Cd(5-Cl-salo){sub 2}(bipy)]{sub 2} (2), [Cd(5-Cl-salo){sub 2}(phen)]{sub 2} (3), [Cd(5-Cl-salo)(neoc)(ONO{sub 2})]{sub 2} (4) and [Cd(5-Cl-salo)(dpamΗ)(ONO{sub 2})]{sub 2} (5). The complexes were characterized by spectroscopic techniques (IR, UV‐vis, {sup 1}H-NMR and {sup 13}C–NMR), elemental analysis and molar conductivity measurements. The structures of four complexes (1–3 and 5) were determined by X-ray crystallography, providing all three possible coordination modes of the ligand 5-Cl-salicylaldehyde, i.e. bidentate or tridentate chelating and/or bridging mode. The complexes bind to calf-thymus (CT) DNA mainly by intercalation, as concluded by the viscosity measurements and present relatively high DNA-binding constants. The complexes exhibit significant ability to displace ethidium bromide (EB) from the EB-DNA complex, thus indirectly proving the intercalation as the most possible binding mode to CT DNA. - Graphical abstract: Cadmium complexes of the formulae [Cd(5-Cl-salo){sub 2}(CH{sub 3}OH)]{sub 2} and [Cd(5-Cl-salo){sub 2}(α-diimine)]{sub 2} or [Cd(5-Cl-salo)(α-diimine)(ONO{sub 2})]{sub 2} have been synthesized and characterized. The complexes bind tightly to CT DNA probably by intercalation competing with ethidium bromide for the intercalation site of DNA. - Highlights: • Synthesis of a series of dinuclear Cd complexes • The complexes characterized by diverse techniques. • The crystal structures of four complexes have been determined. • Intercalation is the most possible binding mode of the complexes to DNA. • The complexes compete with ethidium bromide for the DNA-intercalating sites.

Methylene-bis[(aminomethyl)phosphinic acids]: synthesis, acid-base and coordination properties.

Science.gov (United States)

David, Tomáš; Procházková, Soňa; Havlíčková, Jana; Kotek, Jan; Kubíček, Vojtěch; Hermann, Petr; Lukeš, Ivan

2013-02-21

Three symmetrical methylene-bis[(aminomethyl)phosphinic acids] bearing different substituents on the central carbon atom, (NH(2)CH(2))PO(2)H-C(R(1))(R(2))-PO(2)H(CH(2)NH(2)) where R(1) = OH, R(2) = Me (H(2)L(1)), R(1) = OH, R(2) = Ph (H(2)L(2)) and R(1),R(2) = H (H(2)L(3)), were synthesized. Acid-base and complexing properties of the ligands were studied in solution as well as in the solid state. The ligands show unusually high basicity of the nitrogen atoms (log K(1) = 9.5-10, log K(2) = 8.5-9) if compared with simple (aminomethyl)phosphinic acids and, consequently, high stability constants of the complexes with studied divalent metal ions. The study showed the important role of the hydroxo group attached to the central carbon atom of the geminal bis(phosphinate) moiety. Deprotonation of the hydroxo group yields the alcoholate anion which tends to play the role of a bridging ligand and induces formation of polynuclear complexes. Solid-state structures of complexes [H(2)N=C(NH(2))(2)][Cu(2)(H(-1)L(2))(2)]CO(3)·10H(2)O and Li(2)[Co(4)(H(-1)L(1))(3)(OH)]·17.5H(2)O were determined by X-ray diffraction. The complexes show unexpected geometries forming dinuclear and cubane-like structures, respectively. The dinuclear copper(II) complex contains a bridging μ(2)-alcoholate group with the (-)O-P(=O)-CH(2)-NH(2) fragments of each ligand molecule chelated to the different central ion. In the cubane cobalt(II) complex, one μ(3)-hydroxide and three μ(3)-alcoholate anions are located in the cube vertices and both phosphinate groups of one ligand molecule are chelating the same cobalt(II) ion while each of its amino groups are bound to different neighbouring metal ions. All such three metal ions are bridged by the alcoholate group of a given ligand.

Synthesis, Characterization and DNA Cleavage of Copper(II ...

African Journals Online (AJOL)

Purpose: To study deoxyribonucleic acid (DNA) shearing capability of copper(II) complex of dithiothreitol (DTT) and to fevaluate its potential application in cancer therapy. Methods: A parrot green complex was synthesized by grinding copper acetate monohydrate and DTT in 1:2 molar ratio in a mortar until no fumes of acetic ...

Parent di-nuclear quasimolecular states as exotic resonant states

International Nuclear Information System (INIS)

Grama, N.

2002-01-01

It in shown that the parent di-nuclear quasimolecular state is an exotic resonant state that corresponds to a S-matrix pole in the neighbourhood of an attractor in the k-plane. The properties of the parent quasimolecular states i.e. energy, widths, deviation from the linear dependence of the energy on l(l + 1) doorway character and criteria for observability, result naturally from the general properties of the exotic resonant states. (author)

Standard molar enthalpies of formation of copper(II) β-diketonates and monothio-β-diketonates

International Nuclear Information System (INIS)

Ribeiro da Silva, Manuel A.V.; Santos, Luis M.N.B.F.

2006-01-01

The standard (p o =0.1MPa) molar enthalpies of formation of the crystalline complexes of dibenzoylmethane (Hdbm), thenoyltrifluoroacetone (Httfa), monothiodibenzoylmethane (HdbmS), and monothiothenoyltrifluoroacetone (HttfaS) of copper(II) were determined, at T=298.15K, by high precision solution-reaction calorimetry. The standard molar enthalpies of sublimation of the copper(II) β-diketonate complexes were measured by high-temperature Calvet microcalorimetry. From the standard molar enthalpies of formation of the complexes in the gaseous state, the mean molar dissociation enthalpies copper(II)-ligand, m >(Cu-L), were derived. Δ f H m o (cr)Δ cr g H m o kJ.mol -1 kJ.mol -1 Bis(dibenzoylmethanate)copper(II), Cu(dbm) 2 -364.0+/-3.9230.7+/-8.2Bis(thenoyltrifluoroacetonate)copper(II), Cu(ttfa) 2 -1824.3+/-8.3167.9+/-7.4Bis(monothiodibenzoylmethanate)copper(II), Cu(dbmS) 2 35.6+/-7.7[241+/-15]Bis(monothiothenoyltrifluoroacetonate) copper(II), Cu(ttfaS) 2 -1405.7+/-8.3[177+/-15

Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

KAUST Repository

Dehury, Niranjan; Maity, Niladri; Tripathy, Suman Kumar; Basset, Jean-Marie; Patra, Srikanta

2016-01-01

Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction

Oligo-m-phenyleneoxalamide copper(II) mesocates as electro-switchable ferromagnetic metal-organic wires.

Science.gov (United States)

Pardo, Emilio; Ferrando-Soria, Jesús; Dul, Marie-Claire; Lescouëzec, Rodrigue; Journaux, Yves; Ruiz-García, Rafael; Cano, Joan; Julve, Miguel; Lloret, Francesc; Cañadillas-Delgado, Laura; Pasán, Jorge; Ruiz-Pérez, Catalina

2010-11-15

Double-stranded copper(II) string complexes of varying nuclearity, from di- to tetranuclear species, have been prepared by the Cu(II)-mediated self-assembly of a novel family of linear homo- and heteropolytopic ligands that contain two outer oxamato and either zero (1 b), one (2 b), or two (3 b) inner oxamidato donor groups separated by rigid 2-methyl-1,3-phenylene spacers. The X-ray crystal structures of these Cu(II) (n) complexes (n=2 (1 d), 3 (2 d), and 4 (3 d)) show a linear array of metal atoms with an overall twisted coordination geometry for both the outer CuN(2)O(2) and inner CuN(4) chromophores. Two such nonplanar all-syn bridging ligands 1 b-3 b in an anti arrangement clamp around the metal centers with alternating M and P helical chiralities to afford an overall double meso-helicate-type architecture for 1 d-3 d. Variable-temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 d-3 d show the occurrence of S=nS(Cu) (n=2-4) high-spin ground states that arise from the moderate ferromagnetic coupling between the unpaired electrons of the linearly disposed Cu(II) ions (S(Cu)=1/2) through the two anti m-phenylenediamidate-type bridges (J values in the range of +15.0 to 16.8 cm(-1)). Density functional theory (DFT) calculations for 1 d-3 d evidence a sign alternation of the spin density in the meta-substituted phenylene spacers in agreement with a spin polarization exchange mechanism along the linear metal array with overall intermetallic distances between terminal metal centers in the range of 0.7-2.2 nm. Cyclic voltammetry (CV) and rotating-disk electrode (RDE) electrochemical measurements for 1 d-3 d show several reversible or quasireversible one- or two-electron steps that involve the consecutive metal-centered oxidation of the inner and outer Cu(II) ions (S(Cu)=1/2) to diamagnetic Cu(III) ones (S(Cu)=0) at relatively low formal potentials (E values in the range of

Síntese de acetato de celulose a partir da palha de feijão utilizando N-bromossuccinimida (NBS como catalisador

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Sarah S. Brum

2012-01-01

Full Text Available Neste estudo a celulose obtida da palha de feijão foi utilizada para produzir um material hidrofóbico (acetato de celulose para ser avaliado como absorvente de óleo. Nas reações de acetilação foram utilizados anidrido acético e dois catalisadores, a piridina (PY e N-bromossuccinimida (NBS. Os materiais produzidos foram caracterizados por espectroscopia na região do infravermelho médio, microscopia eletrônica de varredura, difratometria de raios-X e análise elementar. O NBS mostrou-se mais eficiente que a PY e, seu uso resultou em materiais com maiores quantidades de grupos acetatos, mais hidrofóbicos e com maiores capacidades de absorção de óleo de soja.

Experimental evidence for the involvement of dinuclear alkynylcopper(I) complexes in alkyne-azide chemistry.

Science.gov (United States)

Buckley, Benjamin R; Dann, Sandra E; Heaney, Harry

2010-06-01

Dinuclear alkynylcopper(I) ladderane complexes are prepared by a robust and simple protocol involving the reduction of Cu(2)(OH)(3)OAc or Cu(OAc)(2) by easily oxidised alcohols in the presence of terminal alkynes; they function as efficient catalysts in copper-catalysed alkyne-azide cycloaddition reactions as predicted by the Ahlquist-Fokin calculations. The same copper(I) catalysts are formed during reactions by using the Sharpless-Fokin protocol. The experimental results also provide evidence that sodium ascorbate functions as a base to deprotonate terminal alkynes and additionally give a convincing alternative explanation for the fact that the Cu(I)-catalysed reactions of certain 1,3-diazides with phenylacetylene give bis(triazoles) as the major products. The same dinuclear alkynylcopper(I) complexes also function as catalysts in cycloaddition reactions of azides with 1-iodoalkynes.

The DFT Calculations of Structures and EPR Parameters for the Dinuclear Paddle-Wheel Copper(II) Complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3) as Powder or Single Crystal

Science.gov (United States)

Ding, Chang-Chun; Wu, Shao-Yi; Xu, Yong-Qiang; Zhang, Li-Juan; Zhang, Zhi-Hong; Zhu, Qin-Sheng; Wu, Ming-He; Teng, Bao-Hua

2017-10-01

Density functional theory (DFT) calculations of the structures and the Cu2+ g factors (gx, gy and gz ) and hyperfine coupling tensor A (Ax , Ay and Az ) were performed for the paddle-wheel (PW)-type binuclear copper(II) complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3) powder and single crystal. Calculations were carried out with the ORCA software using the functionals BHandHlyp, B3P86 and B3LYP with five different basis sets: 6-311g, 6-311g(d,p), VTZ, def-2 and def2-TZVP. Results were tested by the MPAD analysis to find the most suitable functional and basis sets. The electronic structure and covalency between copper and oxygen were investigated by the electron localisation function and the localised orbital locator as well as the Mayer bond order for the [CuO5] group. The optical spectra were theoretically calculated by the time-dependent DFT module and plotted by the Multiwfn program for the [CuO5] group and reasonably associated with the local structure in the vicinity of the central ion copper. In addition, the interactions between the OCNH2CH3, NH3 and H2O molecules and the uncoordinated PW copper(II) complex were studied, and the corresponding adsorption energies, the frequency shifts with respect to the free molecules and the changes of the Cu-Cu distances were calculated and compared with the relevant systems.

CFD simulation of copper(II) extraction with TFA in non-dispersive hollow fiber membrane contactors.

Science.gov (United States)

Muhammad, Amir; Younas, Mohammad; Rezakazemi, Mashallah

2018-04-01

This study presents computational fluid dynamics (CFD) simulation of dispersion-free liquid-liquid extraction of copper(II) with trifluoroacetylacetone (TFA) in hollow fiber membrane contactor (HFMC). Mass and momentum balance Navier-Stokes equations were coupled to address the transport of copper(II) solute across membrane contactor. Model equations were simulated using COMSOL Multiphysics™. The simulation was run to study the detailed concentration distribution of copper(II) and to investigate the effects of various parameters like membrane characteristics, partition coefficient, and flow configuration on extraction efficiency. Once-through extraction was found to be increased from 10 to 100% when partition coefficient was raised from 1 to 10. Similarly, the extraction efficiency was almost doubled when porosity to tortuosity ratio of membrane was increased from 0.05 to 0.81. Furthermore, the study revealed that CFD can be used as an effective optimization tool for the development of economical membrane-based dispersion-free extraction processes.

Standard molar enthalpies of formation of copper(II) {beta}-diketonates and monothio-{beta}-diketonates

Energy Technology Data Exchange (ETDEWEB)

Ribeiro da Silva, Manuel A.V. [Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)]. E-mail: risilva@fc.up.pt; Santos, Luis M.N.B.F. [Centro de Investigacao em Quimica, Departamento de Quimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 687, P-4169-007 Porto (Portugal)

2006-07-15

The standard (p{sup o}=0.1MPa) molar enthalpies of formation of the crystalline complexes of dibenzoylmethane (Hdbm), thenoyltrifluoroacetone (Httfa), monothiodibenzoylmethane (HdbmS), and monothiothenoyltrifluoroacetone (HttfaS) of copper(II) were determined, at T=298.15K, by high precision solution-reaction calorimetry. The standard molar enthalpies of sublimation of the copper(II) {beta}-diketonate complexes were measured by high-temperature Calvet microcalorimetry. From the standard molar enthalpies of formation of the complexes in the gaseous state, the mean molar dissociation enthalpies copper(II)-ligand, (Cu-L), were derived. {delta}{sub f}H{sub m}{sup o} (cr){delta}{sub cr}{sup g}H{sub m}{sup o} kJ.mol{sup -1}kJ.mol{sup -1}Bis(dibenzoylmethanate)copper(II), Cu(dbm){sub 2}-364.0+/-3.9230.7+/-8.2Bis(thenoyltrifluoroacetonate)copper(II), Cu(ttfa){sub 2}-1824.3+/-8.3167.9+/-7.4Bis(monothiodibenzoylmethanate)copper(II), Cu(dbmS){sub 2}35.6+/-7.7[241+/-15]Bis(monothiothenoyltrifluoroacetonate) copper(II), Cu(ttfaS){sub 2}-1405.7+/-8.3[177+/-15].

Performance Evaluation of Monolith Based Immobilized Acetylcholinesterase Flow-Through Reactor for Copper(II Determination with Spectrophotometric Detection

Directory of Open Access Journals (Sweden)

Parawee Rattanakit

2014-01-01

Full Text Available A monolith based immobilized acetylcholinesterase (AChE flow-through reactor has been developed for the determination of copper(II using flow injection spectrophotometric system. The bioreactor was prepared inside a microcapillary column by in situ polymerization of butyl methacrylate, ethylene dimethacrylate, and 2,2-dimethoxy-1,2-diphynyletane-1-one in the presence of 1-decanol, followed by vinyl azlactone functionalization and AChE immobilization. The behavior of AChE before and after being immobilized on the monolith was evaluated by kinetic parameters from Lineweaver and Burk equation. The detection was based on measuring inhibition effect on the enzymatic activity of AChE by copper(II using Ellman’s reaction with spectrophotometric detection at 410 nm. The linear range of the calibration graph was obtained over the range of 0.02–3.00 mg L−1. The detection limit, defined as 10% inhibition (I10, was found to be 0.04 mg L−1. The repeatability was 3.35 % (n=5 for 1.00 mg L−1 of copper(II. The proposed method was applied to the determination of copper(II in natural water samples with sampling rate of 4 h−1.

Immobilized copper(II) macrocyclic complex on MWCNTs with antibacterial activity

Energy Technology Data Exchange (ETDEWEB)

Tarlani, Aliakbar, E-mail: Tarlani@ccerci.ac.ir [Inorganic Nanostructures and Catalysts Research Lab., Chemistry & Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj Hwy, Tehran 14968-13151 (Iran, Islamic Republic of); Narimani, Khashayar [Inorganic Nanostructures and Catalysts Research Lab., Chemistry & Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj Hwy, Tehran 14968-13151 (Iran, Islamic Republic of); Mohammadipanah, Fatemeh; Hamedi, Javad [Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran 14155-6455 (Iran, Islamic Republic of); University of Tehran Biocompound Collection (UTBC), Microbial Technology and Products Research Center, University of Tehran, Tehran (Iran, Islamic Republic of); Tahermansouri, Hasan [Department of Chemistry, Ayatollah Amoli Branch, Islamic Azad University, Amol (Iran, Islamic Republic of); Amini, Mostafa M. [Department of Chemistry, Shahid Behshti University, 1983963113, Tehran (Iran, Islamic Republic of)

2015-06-30

Graphical abstract: In an antibacterial test, grafted copper(II) macrocyclic complex on the surface of MWCNT showed higher antibacterial activity against Bacillus subtilis compared to the individual MWCNT-COOH and the complex. - Highlights: • Copper(II) tetraaza macrocyclic complex covalently bonded to modified MWCNT. • Grafting of the complex carried out via an interaction between −C(=O)Cl group and NH of the ligand. • The samples were subjected in an antibacterial assessment to compare their activity. • Immobilized complex showed higher antibacterial activity against Bacillus subtilis ATCC 6633 compared to separately MWCNT-C(C=O)-OH and CuTAM. - Abstract: In a new approach, a copper(II) tetraaza macrocyclic complex (CuTAM) was covalently bonded on modified multi-walled carbon nanotubes (MWCNTs). To achieve this purpose, MWCNTs were converted to MWCNT-COCl and then reacted to NH groups of TAM ligand. The prepared material was characterized by Fourier Transform Infrared (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, thermal gravimetric analysis (TGA), and FESEM (field emission scanning electron microscopy). FT-IR and TGA demonstrated the presence of the organic moieties, and XRD proved that the structure of MWCNTs remained intact during the three modification steps. An increase in the I{sub D}/I{sub G} ratio in Raman spectra confirmed the surface modifications. Finally, the samples were subjected to an antibacterial assessment to compare their biological activity. The antibacterial test showed that the grafted complex on the surface of the nanotube (MWCNT-CO-CuTAM) has higher antibacterial activity against Bacillus subtilis ATCC 6633 than the MWCNT-COOH and CuTAM with 1000 and 2000 μg/mL.

Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II oxalate precursor layers

Directory of Open Access Journals (Sweden)

Kai Rückriem

2016-06-01

Full Text Available Copper(II oxalate grown on carboxy-terminated self-assembled monolayers (SAM using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS. Helium ion microscopy (HIM reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor.

Slow magnetic relaxation in carbonato-bridged dinuclear lanthanide(III) complexes with 2,3-quinoxalinediolate ligands.

Science.gov (United States)

Vallejo, Julia; Cano, Joan; Castro, Isabel; Julve, Miguel; Lloret, Francesc; Fabelo, Oscar; Cañadillas-Delgado, Laura; Pardo, Emilio

2012-08-11

The coordination chemistry of the 2,3-quinoxalinediolate ligand with different lanthanide(III) ions in basic media in air affords a new family of carbonato-bridged M(2)(III) compounds (M = Pr, Gd and Dy), the Dy(2)(III) analogue exhibiting slow magnetic relaxation behaviour typical of single-molecule magnets.

Gasto energético e medidas antropométricas de novas usuárias do contraceptivo injetável trimestral de acetato de medroxiprogesterona de depósito

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Priscilla de Nazaré Silva dos SANTOS

2015-10-01

Full Text Available Objetivo:Avaliar o gasto energético e as medidas antropométricas de mulheres durante o primeiro ano de uso do método contraceptivo de acetato de medroxiprogesterona de depósito.Métodos:Estudo prospectivo com grupo de comparação. Foram incluídas mulheres saudáveis, não obesas, nunca usuárias de acetato de medroxiprogesterona de depósito e sem antecedentes que pudessem contribuir para a variação do peso corporal; foram distribuídas em dois grupos, 28 usuárias de acetato de medroxiprogesterona e 24 usuárias de dispositivo intrauterino de cobre, pareadas por idade (±1 ano e índice de massa corporal (kg/m2. As variáveis estudadas foram sociodemográficas (idade, etnia, tabagismo, etilismo, atividade física, classe econômica e escolaridade, peso (kg, índice de massa corporal, gasto energético basal e total, medidas de circunferência de cintura e quadril (cm e relação cintura-quadril.Resultados:A idade das mulheres variou de 20-39 anos. As médias de idade/índice de massa corporal foram 29,6 (DP=±5,2 anos/23,9 (±3,6 kg/m2, no grupo de acetato de medroxiprogesterona de depósito, e de 28,6 (DP=±5,2 anos/ 24,5 (±2,7 kg/m2, no grupo de dispositivo intrauterino de cobre. Após análise de variância para medidas repetidas, as usuárias de acetato de medroxiprogesterona de depósito apresentaram ganho de 2,2 kg no peso corporal e de -0,2 kg no grupo do dispositivo intrauterino de cobre, sem diferença estatisticamente significativa entre eles. Não houve discrepância nas demais variáveis estudadas.Conclusão:Mulheres saudáveis e jovens não apresentaram mudança no peso, nas medidas e nos gastos energéticos durante o primeiro ano de uso do contraceptivo acetato de medroxiprogesterona. A orientação em relação aos hábitos saudáveis de vida e o monitoramento de medidas são importantes para o controle do peso corporal em usuárias de métodos contraceptivos.

A novel asymmetric chair-like hydroxyl-bridged tetra-copper compound: Synthesis, supramolecular structure and magnetic property

Science.gov (United States)

Wang, Xiao-Feng; Du, Ke-Jie; Wang, Hong-Qing; Zhang, Xue-Li; Nie, Chang-Ming

2017-06-01

A new polynuclear Cu(II) compound, [Cu4(bpy)4(OH)4(H2O)(BTC)]NO3·8H2O (1), was prepared by self-assembly from the solution of copper(II) nitrate and two kinds of ligands, 2,2‧-bipyridine (bpy) and benzene-tricarboxylic acid (H3BTC). Single crystal structure analysis reveals that 1 features a rare asymmetric chair-like hydroxyl-bridged tetra-copper cluster: [Cu4(OH)4] core along with one H2O and one BTC3- occupied each terminal coordinated site. In addition, the magnetic property has been investigated.

Mixed-ligand copper(II) complexes of dipicolylamine and 1,10 ...

Indian Academy of Sciences (India)

Unknown

DNA repair mechanism.13,14 Copper(II) complexes containing heterocyclic bases have received consid- erable current interest in nucleic acid chemistry due to their diverse applications following the discovery of the “chemical nuclease” activity of the [Cu. (phen)2]+ (phen = 1,10-phenanthroline) complex in the presence of ...

Synthesis, characterization and biological activity of symmetric dinuclear complexes derived from a novel macrocyclic compartmental ligand

Energy Technology Data Exchange (ETDEWEB)

Mruthyunjayaswamy, B.H.M.; Ijare, Omkar B.; Jadegoud, Y. [Gulbarga University (India). Dept. of Chemistry]. E-mail: bhmmswamy53@rediffmail.com

2005-07-15

A phenol based novel macrocyclic binucleating compartmental ligand N,N-bis(2,6-diiminomethyl-4-methyl-1-hydroxyphenyl)malonoyldicarboxamide was prepared. The complexes were prepared by template method by reacting 2,6-diformyl-4-methylphenol, malonoyl dihydrazide and the metal chlorides of Cu(II), Ni(II), Co(II), Cd(II), Zn(II) and Hg(II) in methanol to get a series of dinuclear complexes. The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility data, IR, UV-Vis, ESR, NMR and FAB mass spectral data. The dinuclear nature of the complexes was confirmed on the basis of elemental analyses, magnetic susceptibility, ESR and FAB mass spectral data. The ligand as well as Cu(II), Ni(II), Co(II) and Zn(II) complexes were tested for their antibacterial and antifungal properties against Escherichia coli, Staphyloccocus aureus, Aspergillus niger and Fusarium oxysporum. Magnetic susceptibility measurements of Cu(II), Ni(II) and Co(II) complexes reveal that these complexes exhibit antiferromagnetic coupling behavior due to the presence of two metal ions in close proximity. FAB mass spectrum of the Cu(II) complex gave a clear evidence for the dinuclear nature. The ligand and the complexes were found to be less active against the tested bacteria, but the ligand alone was found active against the fungus Fusarium oxysporum. (author)

Synthesis, characterization and biological activity of symmetric dinuclear complexes derived from a novel macrocyclic compartmental ligand

International Nuclear Information System (INIS)

Mruthyunjayaswamy, B.H.M.; Ijare, Omkar B.; Jadegoud, Y.

2005-01-01

A phenol based novel macrocyclic binucleating compartmental ligand N,N-bis(2,6-diiminomethyl-4-methyl-1-hydroxyphenyl)malonoyldicarboxamide was prepared. The complexes were prepared by template method by reacting 2,6-diformyl-4-methylphenol, malonoyl dihydrazide and the metal chlorides of Cu(II), Ni(II), Co(II), Cd(II), Zn(II) and Hg(II) in methanol to get a series of dinuclear complexes. The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility data, IR, UV-Vis, ESR, NMR and FAB mass spectral data. The dinuclear nature of the complexes was confirmed on the basis of elemental analyses, magnetic susceptibility, ESR and FAB mass spectral data. The ligand as well as Cu(II), Ni(II), Co(II) and Zn(II) complexes were tested for their antibacterial and antifungal properties against Escherichia coli, Staphyloccocus aureus, Aspergillus niger and Fusarium oxysporum. Magnetic susceptibility measurements of Cu(II), Ni(II) and Co(II) complexes reveal that these complexes exhibit antiferromagnetic coupling behavior due to the presence of two metal ions in close proximity. FAB mass spectrum of the Cu(II) complex gave a clear evidence for the dinuclear nature. The ligand and the complexes were found to be less active against the tested bacteria, but the ligand alone was found active against the fungus Fusarium oxysporum. (author)

Obtención de mapas de curvas residuales para la síntesis de acetato de butilo

Directory of Open Access Journals (Sweden)

Álvaro Orjuela Londoño

2006-09-01

Full Text Available Es este trabajo se adelantó un estudio en la escala de laboratorio de la síntesis acetato de n-butilo en fase líquida (P atm = 560 mmHg, en operación simultánea de reacción y destilación (destilación reactiva batch, utilizando una resina de intercambio catiónico (Lewatit K-2431 como catalizador. Por medio de la construcción experimental de curvas residuales, utilizando diferentes cargas de catalizador, se determinaron las condiciones para las cuales la operación esta limitada por el equilibrio químico de la reacción (régimen de equilibrio y no por efectos cinéticos (régimen cinético. Finalmente, se estableció la factibilidad de implementación del proceso de esterificación a través de un arreglo de reacción-separación simultanea. En dicho proceso se podrIa obtener el acetato de n-butilo puro como producto de fondos de una columna de destilación reactiva, sobrepasando las limitantes de conversión del sistema reactivo.

Synthesis and magnetism of μ-oxamido-bridged Cu2IILnIII - type heterotrinuclear complexes (Ln = Ce, Nd, Sm, Eu, Gd, Tb, Dy, Er)

International Nuclear Information System (INIS)

Li, Y.T.; Yan, C.W.

2001-01-01

Eight new Cu 2 II Ln III - type (Ln = Ce, Nd, Sm, Eu, Gd, Tb, Dy, Er) heterotrinuclear complexes bridged by N,N'-bis (2-aminopropyl)oxamidocopper(II) [Cu(oxdn)], namely Cu 2 (oxdn)Ln(NO 3 ) 3 , have been synthesized and characterized by elemental analyses, molar conductivity measurements and spectroscopic (IR, UV, ESR) studies. Magnetic susceptibility measurements (4.2 ∼300 K) and studies of Cu 2 (oxdn)Gd(NO 3 ) 3 complex have revealed that the central gadolinium(III) and terminal copper(II) ions are ferromagnetically coupled with the exchange integral J (Cu-Gd) = +2.98 cm -1 , while an antiferromagnetic coupling is detected between the terminal copper(II) metal ions with the exchange integral J' (Cu-Gd) = -0.75 cm -1 , on the basis of the spin Hamiltonian operator [H -2J(S Cu1 -S Gd +S Cu2 +S Gd )-2J'(S Cu1 S Cu2 )]. (author)

The thermal decomposition of copper(II) oxalate revisited

International Nuclear Information System (INIS)

Lamprecht, Emmanuel; Watkins, Gareth M.; Brown, Michael E.

2006-01-01

DSC, TG and TG-FT-IR, and XRPD have been used to examine the effects of supposedly inert atmospheres of argon and nitrogen on the mechanism of the thermal decomposition of copper(II) oxalate. The DSC curves in pure argon at 10 deg. C min -1 show a broad endotherm with onset at about 280 deg. C and maximum at about 295 deg. C. In mixtures of argon and nitrogen, as the proportion of argon gas is decreased, the endothermic character of the decomposition decreases until, when nitrogen is the main component, the decomposition exhibits a complex broad exothermic character. XRPD studies showed that, regardless of the proportions of nitrogen and argon, the DSC residues consisted of mainly copper metal with small amounts of copper(I) oxide (cuprite) and, under some conditions, traces of copper(II) oxide (tenorite). Various explanations for this behaviour are discussed and a possible answer lies in the disproportionation of CO 2 (g) to form small quantities of O 2 (g) or monatomic oxygen. The possibility exists that the exothermicity in nitrogen could be explained by reaction of the nitrogen with atomic oxygen to form N 2 O(g), but this product could not be detected using TG-FT-IR

The thermal decomposition of copper(II) oxalate revisited

Energy Technology Data Exchange (ETDEWEB)

Lamprecht, Emmanuel [Chemistry Department, Rhodes University, Grahamstown 6140 (South Africa); Watkins, Gareth M. [Chemistry Department, Rhodes University, Grahamstown 6140 (South Africa); Brown, Michael E. [Chemistry Department, Rhodes University, Grahamstown 6140 (South Africa)]. E-mail: m.brown@ru.ac.za

2006-07-01

DSC, TG and TG-FT-IR, and XRPD have been used to examine the effects of supposedly inert atmospheres of argon and nitrogen on the mechanism of the thermal decomposition of copper(II) oxalate. The DSC curves in pure argon at 10 deg. C min{sup -1} show a broad endotherm with onset at about 280 deg. C and maximum at about 295 deg. C. In mixtures of argon and nitrogen, as the proportion of argon gas is decreased, the endothermic character of the decomposition decreases until, when nitrogen is the main component, the decomposition exhibits a complex broad exothermic character. XRPD studies showed that, regardless of the proportions of nitrogen and argon, the DSC residues consisted of mainly copper metal with small amounts of copper(I) oxide (cuprite) and, under some conditions, traces of copper(II) oxide (tenorite). Various explanations for this behaviour are discussed and a possible answer lies in the disproportionation of CO{sub 2}(g) to form small quantities of O{sub 2}(g) or monatomic oxygen. The possibility exists that the exothermicity in nitrogen could be explained by reaction of the nitrogen with atomic oxygen to form N{sub 2}O(g), but this product could not be detected using TG-FT-IR.

Dinuclear 1,4,7-triazacyclononane (tacn) complexes of cobalt(III) with amido and tacn bridges. Synthesis, characterization and reversible acid-accelerated bridge cleavage

DEFF Research Database (Denmark)

Andersen, Peter; Glerup, Jørgen; Gumm, Andreas

2004-01-01

-tacn(-H)]Co(NH3)]3+, were isolated as perchlorates, and the crystal structure of the perrhenate of the latter complex was determined by X-ray diffraction. In this compound a nitrogen atom (deprotonated) from one of the tacn ligands forms a third bridge together with two amido bridges. In 1.0 M (Na,H)ClO4 ([H+] 0......)]4+. An isolated perchlorate of this complex appeared to be the salt of the trans-ammineaqua isomer as determined by X-ray diffraction. Equilibration from both sides fits the first-order rate constant dependence k(obs)=6.2(3) x 10(-5)[H+] + 2.1(2) x 10(-5)(s(-1)) at 40 degrees C. Prolonged treatment of the two...

Bis{(E-3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropan-1-aminium} bis[μ-(E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamido(2−]bis{[(E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamide]copper(II} bis((E-{3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropyl}carbamate acetonitrile disolvate

Directory of Open Access Journals (Sweden)

Andrii I. Buvailo

2012-12-01

Full Text Available The reaction between copper(II nitrate and (E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamide led to the formation of the dinuclear centrosymmetric copper(II title complex, (C8H18N3O22[Cu2(C8H15N3O22(C8H17N3O22](C9H16N3O42·2CH3CN, in which an inversion center is located at the midpoint of the Cu2 unit in the center of the neutral [Cu2(C8H15N3O22(C8H17N3O22] complex fragment. The Cu2+ ions are connected by two N—O bridging groups [Cu...Cu separation = 4.0608 (5 Å] while the CuII ions are five-coordinated in a square-pyramidal N4O coordination environment. The complex molecule co-crystallizes with two molecules of acetonitrile, two molecules of the protonated ligand (E-3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropan-1-aminium and two negatively charged (E-{3-[2-(hydroxyiminopropanamido]-2,2-dimethylpropyl}carbamate anions, which were probably formed as a result of condensation between (E-N-(3-amino-2,2-dimethylpropyl-2-(hydroxyiminopropanamide and hydrogencarbonate anions. In the crystal, the complex fragment [Cu2(C8H15N3O22(C8H17N3O22] and the ion pair C8H18N3O2+.C9H16N3O4− are connected via an extended system of hydrogen bonds.

A family of acetato-diphenoxo triply bridged dimetallic Zn(II)Ln(III) complexes: SMM behavior and luminescent properties.

Science.gov (United States)

Oyarzabal, Itziar; Artetxe, Beñat; Rodríguez-Diéguez, Antonio; García, JoséÁngel; Seco, José Manuel; Colacio, Enrique

2016-06-21

Eleven dimetallic Zn(II)-Ln(III) complexes of the general formula [Zn(µ-L)(µ-OAc)Ln(NO3)2]·CH3CN (Ln(III) = Pr (1), Nd (2), Sm (3), Eu (4), Gd (5), Tb (6), Dy (7), Ho (8), Er (9), Tm (10), Yb (11)) have been prepared in a one-pot reaction from the compartmental ligand N,N'-dimethyl-N,N'-bis(2-hydroxy-3-formyl-5-bromo-benzyl)ethylenediamine (H2L). In all these complexes, the Zn(II) ions occupy the internal N2O2 site whereas the Ln(III) ions show preference for the O4 external site. Both metallic ions are bridged by an acetate bridge, giving rise to triple mixed diphenoxido/acetate bridged Zn(II)Ln(III) compounds. The Nd, Dy, Er and Yb complexes exhibit field induced single-ion magnet (SIM) behaviour, with Ueff values ranging from 14.12 to 41.55 K. The Er complex shows two relaxation processes, but only the second relaxation process with an energy barrier of 21.0 K has been characterized. The chromophoric L(2-) ligand is able to act as an "antenna" group, sensitizing the near-infrared (NIR) Nd(III) and Yb(III)-based luminescence in complexes 2 and 11 and therefore, both compounds can be considered as magneto-luminescent materials. In addition, the Sm(III), Eu(III) and Tb(III) derivatives exhibit characteristic emissions in the visible region.

Copper(II) complexes of methimazole, an anti Grave's disease drug. Synthesis, characterization and its potential biological behavior as alkaline phosphatase inhibitor.

Science.gov (United States)

Urquiza, Nora M; Manca, Silvia G; Moyano, María A; Dellmans, Raquel Arrieta; Lezama, Luis; Rojo, Teófilo; Naso, Luciana G; Williams, Patricia A M; Ferrer, Evelina G

2010-04-01

Methimazole (MeimzH) is an anti-thyroid drug and the first choice for patients with Grave's disease. Two new copper(II) complexes of this drug: [Cu(MeimzH)(2)(NO(3))(2)]*0.5H(2)O and [Cu(MeimzH)(2)(H(2)O)(2)](NO(3))(2)*H(2)O were synthesized and characterized by elemental analysis, dissolution behavior, thermogravimetric analysis and UV-vis, diffuse reflectance, FTIR and EPR spectroscopies. As it is known that copper(II) cation can act as an inhibitor of alkaline phosphatase (ALP), the inhibitory effect of methimazole and its copper(II) complexes on ALP activity has also been investigated.

Potential energy surfaces for nucleon exchanging in dinuclear systems

International Nuclear Information System (INIS)

Li Jianfeng; Xu Hushan; Li Wenfei; Zuo Wei; Li Junqing; Wang Nan; Zhao Enguang

2003-01-01

The experimental measurements have provided the evidence that the suppression of fusion cross-section caused by quasi-fission is very important for the synthesis of super-heavy nuclei by heavy ion collisions. The potential energy surface due to the nucleon transfer in the collision process is the driven potential, which governs the nucleon transfer, so that governs the competition between the fusion and quasi-fission. The dinuclear system potential energy surface also gives the information about the optimum projectile-target combination, as well as the optimum excitation energy for the synthesis of super-heavy nuclei by heavy ion collisions

Spectroscopic and molecular docking studies on the interaction of human serum albumin with copper(II) complexes

Science.gov (United States)

Guhathakurta, Bhargab; Pradhan, Ankur Bikash; Das, Suman; Bandyopadhyay, Nirmalya; Lu, Liping; Zhu, Miaoli; Naskar, Jnan Prakash

2017-02-01

Two osazone based ligands, butane-2,3-dione bis(2‧-pyridylhydrazone) (BDBPH) and hexane-3,4-dione bis(2‧-pyridylhydrazone) (HDBPH), were synthesized out of the 2:1 M Schiff base condensation of 2-hydrazino pyridine respectively with 2,3-butanedione and 3,4-hexanedione. The X-ray crystal structures of both the ligands have been determined. The copper(II) complex of HDBPH has also been synthesized and structurally characterized. HDBPH and its copper(II) complex have thoroughly been characterized through various spectroscopic and analytical techniques. The X-ray crystal structure of the copper complex of HDBPH shows that it is a monomeric Cu(II) complex having 'N4O2' co-ordination chromophore. Interaction of human serum albumin (HSA) with these ligands and their monomeric copper(II) complexes have been studied by various spectroscopic means. The experimental findings show that the ligands as well as their copper complexes are good HSA binders. Molecular docking investigations have also been done to unravel the mode of binding of the species with HSA.

Bis[μ-(E-N-(pyridin-3-ylmethylidenehydroxyamine]-κ2N1:N3;κ2N3:N1-bis{[(E-N-(pyridin-3-ylmethylidene-κNhydroxyamine]silver(I} dinitrate

Directory of Open Access Journals (Sweden)

Shan Gao

2012-12-01

Full Text Available In the centrosymmetric dinuclear title AgI compound, [Ag2(C6H6N2O4](NO32, the aromatic amine-coordinated AgI atom is further bridged by two hydroxylamine molecules that use aromatic and oxime N atoms for bridging, and it exists in a distorted trigonal-planar geometry. In the crystal, the nitrate anions link to the dinuclear compound molecules via O—H...O hydrogen bonds, generating a chain running along the a-axis direction.

Recovery of copper(II) and chromium(III) from nitrate medium with ...

African Journals Online (AJOL)

The solvent extraction of copper(II) and chromium(III) from nitrate medium with salicylideneaniline (HL) is studied as a function of various parameters: pH, concentration of salicylideneaniline, contact time and the nature of anoin (nitrate and sulfate) in aqueous phase. Chromium(III) is not extracted by salicylideneaniline ...

1,5-Diamido-9,10-anthraquinone, a Centrosymmetric Redox-Active Bridge with Two Coupled β-Ketiminato Chelate Functions: Symmetric and Asymmetric Diruthenium Complexes.

Science.gov (United States)

Ansari, Mohd Asif; Mandal, Abhishek; Paretzki, Alexa; Beyer, Katharina; Fiedler, Jan; Kaim, Wolfgang; Lahiri, Goutam Kumar

2016-06-06

The dinuclear complexes {(μ-H2L)[Ru(bpy)2]2}(ClO4)2 ([3](ClO4)2), {(μ-H2L)[Ru(pap)2]2}(ClO4)2 ([4](ClO4)2), and the asymmetric [(bpy)2Ru(μ-H2L)Ru(pap)2](ClO4)2 ([5](ClO4)2) were synthesized via the mononuclear species [Ru(H3L)(bpy)2]ClO4 ([1]ClO4) and [Ru(H3L)(pap)2]ClO4 ([2]ClO4), where H4L is the centrosymmetric 1,5-diamino-9,10-anthraquinone, bpy is 2,2'-bipyridine, and pap is 2-phenylazopyridine. Electrochemistry of the structurally characterized [1]ClO4, [2]ClO4, [3](ClO4)2, [4](ClO4)2, and [5](ClO4)2 reveals multistep oxidation and reduction processes, which were analyzed by electron paramagnetic resonance (EPR) of paramagnetic intermediates and by UV-vis-NIR spectro-electrochemistry. With support by time-dependent density functional theory (DFT) calculations the redox processes could be assigned. Significant results include the dimetal/bridging ligand mixed spin distribution in 3(3+) versus largely bridge-centered spin in 4(3+)-a result of the presence of Ru(II)-stabilizig pap coligands. In addition to the metal/ligand alternative for electron transfer and spin location, the dinuclear systems allow for the observation of ligand/ligand and metal/metal site differentiation within the multistep redox series. DFT-supported EPR and NIR absorption spectroscopy of the latter case revealed class II mixed-valence behavior of the oxidized asymmetric system 5(3+) with about equal contributions from a radical bridge formulation. In comparison to the analogues with the deprotonated 1,4-diaminoanthraquinone isomer the centrosymmetric H2L(2-) bridge shows anodically shifted redox potentials and weaker electronic coupling between the chelate sites.

The DFT calculations of structures and EPR parameters for the dinuclear paddle-wheel copper(II) complex {Cu_2(μ_2-O_2CCH_3)_4}(OCNH{sub 2}CH{sub 3}) as powder or single crystal

Energy Technology Data Exchange (ETDEWEB)

Ding, Chang-Chun; Wu, Shao-Yi; Xu, Yong-Qiang; Zhang, Li-Juan; Zhang, Zhi-Hong; Zhu, Qin-Sheng; Wu, Ming-He; Teng, Bao-Hua [Univ. of Electronic Science and Technology of China, Chengdu (China). School of Physical Electronics

2017-07-01

Density functional theory (DFT) calculations of the structures and the Cu{sup 2+} g factors (g{sub x}, g{sub y} and g{sub z}) and hyperfine coupling tensor A (A{sub x}, A{sub y} and A{sub z}) were performed for the paddle-wheel (PW)-type binuclear copper(II) complex {Cu_2(μ_2-O_2CCH_3)_4}(OCNH{sub 2}CH{sub 3}) powder and single crystal. Calculations were carried out with the ORCA software using the functionals BHandHlyp, B3P86 and B3LYP with five different basis sets: 6-311g, 6-311g(d,p), VTZ, def-2 and def2-TZVP. Results were tested by the MPAD analysis to find the most suitable functional and basis sets. The electronic structure and covalency between copper and oxygen were investigated by the electron localisation function and the localised orbital locator as well as the Mayer bond order for the [CuO{sub 5}] group. The optical spectra were theoretically calculated by the time-dependent DFT module and plotted by the Multiwfn program for the [CuO{sub 5}] group and reasonably associated with the local structure in the vicinity of the central ion copper. In addition, the interactions between the OCNH{sub 2}CH{sub 3}, NH{sub 3} and H{sub 2}O molecules and the uncoordinated PW copper(II) complex were studied, and the corresponding adsorption energies, the frequency shifts with respect to the free molecules and the changes of the Cu-Cu distances were calculated and compared with the relevant systems.

Interesting properties of some iron(II), copper(I) and copper(II ...

Indian Academy of Sciences (India)

Administrator

Tridendate ligands with nitrogen centers, generally well-known as the tripod ligands, have been of considerable interest to inorganic chemists dealing with the preparation of model compounds for hemocyanin, tyrosinase etc. We have found that such ligands when complexed with iron(II) and copper(II) and copper(I) ions ...

Multistep Oxidation of Diethynyl Oligophenylamine-Bridged Diruthenium and Diiron Complexes.

Science.gov (United States)

Zhang, Jing; Guo, Shen-Zhen; Dong, Yu-Bao; Rao, Li; Yin, Jun; Yu, Guang-Ao; Hartl, František; Liu, Sheng Hua

2017-01-17

Homo-dinuclear nonlinear complexes [{M(dppe)Cp*} 2 {μ-(-C≡C) 2 X}] (dppe = 1,2-bis(diphenylphosphino)ethane; Cp* = η 5 -C 5 Me 5 ; X = triphenylamine (TPA), M = Ru (1a) and Fe (1b); X = N,N,N',N'-tetraphenylphenylene-1,4-diamine (TPPD), M = Ru (2a)) were prepared and characterized by 1 H, 13 C, and 31 P NMR spectroscopy and single-crystal X-ray diffraction (1a, 2a). Attempts to prepare the diiron analogue of 2a were not successful. Experimental data obtained from cyclic voltammetry, square wave voltammetry, UV-vis-NIR (NIR = near-infrared) spectro-electrochemistry, and very informative IR spectro-electrochemistry in the C≡C stretching region, combined with density functional theory calculations, afford to make an emphasizing assessment of the close association between the metal-ethynyl termini and the oligophenylamine bridge core as well as their respective involvement in sequential one-electron oxidations of these complexes. The anodic behavior of the homo-bimetallic complexes depends strongly both on the metal center and the length of the oligophenylamine bridge core. The poorly separated first two oxidations of diiron complex 1b are localized on the electronically nearly independent Fe termini. In contrast, diruthenium complex 1a exhibits a significantly delocalized character and a marked electronic communication between the ruthenium centers through the diethynyl-TPA bridge. The ruthenium-ethynyl halves in 2a, separated by the doubly extended and more flexible TPPD bridge core, show a lower degree of electronic coupling, resulting in close-lying first two anodic waves and the NIR electronic absorption of [2a] + with an indistinctive intervalence charge transfer character. Finally, the third anodic waves in the voltammetric responses of the homo-bimetallic complexes are associated with the concurrent exclusive oxidation of the TPA or TPPD bridge cores.

A highly efficient dinuclear Cu(II) chemosensor for colorimetric and fluorescent detection of cyanide in water

Science.gov (United States)

Rhaman, Md. Mhahabubur; Alamgir, Azmain; Wong, Bryan M.; Powell, Douglas R.

2017-01-01

A novel dinuclear copper chemosensor selectively binds cyanide over a wide range of inorganic anions, enabling it to detect cyanide in water up to 0.02 ppm which is 10 times lower than the EPA standard for drinking water. PMID:28217299

Metal-metal bonds involving the f elements. 4. Molecular orbital studies of metal-metal and metal-ligand interactions in dinuclear uranium(V) systems

International Nuclear Information System (INIS)

Cayton, R.H.; Novo-Gradac, K.J.; Bursten, B.E.

1991-01-01

The electronic structures of a series of dinuclear uranium(V) complexes have been investigated using Xα-SW molecular orbital calculations including quasirelativistic corrections. Complexes of the formula U 2 H 10 and U 2 (OH) 10 were used to model the metal-ligand σ and π interactions, respectively, in the known species U 2 (O-i-Pr) 10 . Two basic geometries were investigated: a vertex-sharing bioctahedron with only terminal ligands (D 4h symmetry) and an edge-sharing bioctahedron containing two bridging ligands (D 2h symmetry). The latter geometry, which is that of U 2 (O-i-Pr) 10 , was also examined at U-U bonding and nonbonding distances. The calculations indicate that the U-U interactions are significantly perturbed when H is replaced by OH, owing to strong donation from the OH pπ orbitals into selected U 5f orbitals. The result is a lack of any appreciable U-U interaction for U 2 (OH) 10 in either the D 4h or D 2h geometry. In addition, the overall OH π donation to the U 5f levels is enhanced in the D 2h geometry. The electronic structure of a hypothetical U(V) dimer, Cp 2 U 2 O 4 , was also examined in both bridged and unsupported geometries. The unbridged geometry, like that for U 2 (OH) 10 , suffered from a destabilization of the U-U σ orbital due to ligand π donation and revealed no net U-U bonding. However, the geometry exhibiting two bridging oxo ligands maintains the U-U σ-bonding MO as its lowest energy U 5f orbital. 21 refs., 8 figs., 8 tabs

Quantum transport behavior of Ni-based dinuclear complexes in presence of zigzag graphene nanoribbon as electrode

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Sunandan; Pramanik, Anup; Sarkar, Pranab, E-mail: pranab.sarkar@visva-bharati.ac.in

2016-10-20

Highlights: • Quantum transport properties of some Ni-based dinuclear complexes are investigated. • The materials show various spin dependent properties like NDR, spin filtering, etc. • These are occurred by the influence of edge states of zGNR. • Proper tuning of these materials can alter these phenomena. - Abstract: Quantum transport properties of some Ni-based dinuclear complexes with different polydentate organic ligands have been studied by applying abinitio density functional theory along with nonequilibrium Green’s function formulations. It is demonstrated that these materials are capable of showing multifunctional spin dependent properties by the influence of edge states of zigzag edged graphene nanoribbons. The current–voltage characteristics of these materials show spin dependent negative differential resistance behavior, spin filtering effect, and also voltage rectifying property. Proper tuning of these materials can alter these effects which may be utilized in various spintronic devices.

Effect of Phosphorylation and Copper(II or Iron(II Ions Enrichment on Some Physicochemical Properties of Spelt Starch

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Jacek Rożnowski

Full Text Available ABSTRACT: This paper provides an assessment of the effect of saturation of spelt starch and monostarch phosphate with copper or iron ions on selected physicochemical properties of the resulting modified starches. Native and modified spelt starch samples were analyzed for selected mineral element content using Atomic Absorption Spectroscopy (AAS. Thermodynamic properties were measured using DSC, and pasting properties by RVA. Flow curves of 5% pastes were plotted and described using the Herschel-Bulkley model. The structure recovery ratio was measured. AAS analysis established the presence of iron(II and copper(II ions in the samples of modified starches and that potassium and magnesium ions had leached from them. In comparison to unfortified samples, enriching native starch with copper(II ions decreases value of all temperatures of phase transformation about 1.3-2.7 °C, but in case of monostarch phosphates bigger changes (2.8-3.7 °C were observed. Fortified native spelt starch with copper(II ions caused increasing the final viscosity of paste from 362 to 429 mPa·s. However, presence iron(II ions in samples caused reduced its final viscosity by 170 (spelt starch and 103 mPa·s (monostarch phosphate. Furthermore, enriching monostarch phosphate contributed to reduce degree of structure recovery of pastes from 70.9% to 66.6% in case of copper(II ions and to 59.9% in case of iron(II ions.

Determination of formal redox potentials in aqueous solution of copper(II) complexes with ligands having nitrogen and oxygen donor atoms and comparison with their EPR and UV-Vis spectral features.

Science.gov (United States)

Tabbì, Giovanni; Giuffrida, Alessandro; Bonomo, Raffaele P

2013-11-01

Formal redox potentials in aqueous solution were determined for copper(II) complexes with ligands having oxygen and nitrogen as donor atoms. All the chosen copper(II) complexes have well-known stereochemistries (pseudo-octahedral, square planar, square-based pyramidal, trigonal bipyramidal or tetrahedral) as witnessed by their reported spectroscopic, EPR and UV-visible (UV-Vis) features, so that a rough correlation between the measured redox potential and the typical geometrical arrangement of the copper(II) complex could be established. Negative values have been obtained for copper(II) complexes in tetragonally elongated pseudo-octahedral geometries, when measured against Ag/AgCl reference electrode. Copper(II) complexes in tetrahedral environments (or flattened tetrahedral geometries) show positive redox potential values. There is a region, always in the field of negative redox potentials which groups the copper(II) complexes exhibiting square-based pyramidal arrangements. Therefore, it is suggested that a measurement of the formal redox potential could be of great help, when some ambiguities might appear in the interpretation of spectroscopic (EPR and UV-Vis) data. Unfortunately, when the comparison is made between copper(II) complexes in square-based pyramidal geometries and those in square planar environments (or a pseudo-octahedral) a little perturbed by an equatorial tetrahedral distortion, their redox potentials could fall in the same intermediate region. In this case spectroscopic data have to be handled with great care in order to have an answer about a copper complex geometrical characteristics. © 2013.

Strong copper(II) species in estuarine and sea waters investigated by a method with high detection window.

Science.gov (United States)

Alberti, Giancarla; Biesuz, Raffaela; D'Agostino, Girolamo; Scarponi, Giuseppe; Pesavento, Maria

2007-02-15

The distribution of copper(II) in species of different stability in some estuarine and sea water samples (Adriatic Sea) was investigated by a method based on the sorption of the metal ion on a strongly sorbing resin, Chelex 100, whose sorbing properties have been previously characterized. From them, it is possible to predict very high values of detection windows at the considered conditions, for example side reaction coefficient as high as 10(10) at pH 7.5. Strong copper(II) species in equilibrium with Chelex 100 were detected, at concentration 2-20nM, with a reaction coefficient approximately 10(10.6) at pH 7.45 in sea water, strictly depending on the acidity. They represent 50-70% of the total metal ion and are the strongest copper(II) complexes found in sea water. Weak complexes too were detected in all the samples, with reaction coefficient lower than ca. 10(9) at the same pH. The method applied, named resin titration (RT), was described in a previous investigation, and is here modified in order to be carried out on oceanographic boat during a cruise in the Adriatic Sea.

Unexpected ferromagnetic interaction in a new tetranuclear copper(II) complex: synthesis, crystal structure, magnetic properties, and theoretical studies.

Science.gov (United States)

Fondo, Matilde; García-Deibe, Ana M; Corbella, Monstserrat; Ruiz, Eliseo; Tercero, Javier; Sanmartín, Jesús; Bermejo, Manuel R

2005-07-11

The new tetranuclear carbonate complex [Cu2L)2(CO3)] x 8H2O (1 x 8H2O) (H3L = (2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) has been obtained by two different synthetic routes and fully characterized. Recrystallization of 1 x 8H2O in methanol yields single crystals of {[(Cu2L)2(CO3)]}2 x 12H2O (1 x 6H2O), suitable for X-ray diffraction studies. The crystal structure of 1 x 6H2O shows two crystallographically different tetranuclear molecules in the asymmetric unit, 1a and 1b. Both molecules can be understood as self-assembled from two dinuclear [Cu2L]+ cations, joined by a mu4-eta(2):eta(1):eta(1) carbonate ligand. The copper atoms of each crystallographically different [(Cu2L)2(CO3)] molecule present miscellaneous coordination polyhedra: in both 1a and 1b, two metal centers are in square pyramidal environments, one displays a square planar chromophore and the other one has a geometry that can be considered as an intermediate between square pyramid and trigonal bipyramid. Magnetic studies reveal net intramolecular ferromagnetic coupling between the metal atoms. Density functional calculations allow the assignment of the different magnetic coupling constants and explain the unexpected ferromagnetic behavior, because of the presence of an unusual NCN bridging moiety and countercomplementarity of the phenoxo (or carbonate) and NCN bridges.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a .... Two new hexacoordinated coordination polymers of cadmium(II) containing bridging units only: Syntheses, structures and molecular properties.

Preconcentration and extraction of copper(II) on activated carbon using ethyl-2-quinolyl-β (p-carboxyphenyl hydrazone)dioxo propionate

OpenAIRE

Mehrorang Ghaedi; Farshid Ahmadi; M.R. Baezat; J. Safari

2008-01-01

Activated carbon modified method was used for the preconcentration and determination of copper content in real samples such as tap water, wastewater and a synthetic water sample by flame atomic absorption spectrometry. The copper(II) was adsorbed quantitatively on activated carbon due to its complexation with ethyl-2-quinolyl-β(p-carboxyphenyl hydrazone)dioxo propionate (EQCPDP). The adsorbed copper(II) ion on solid phase was eluted quantitatively by using nitric acid. The important parameter...

Copper(II tetrafluoroborate as mild and versatile catalyst for the

Directory of Open Access Journals (Sweden)

Jihillu. S. Yadav

2008-12-01

Full Text Available A variety of -acetamido ketones and ketoesters are readily prepared in high yields under extremelymild conditions via a three component coupling of aromatic aldehydes, enolizable ketones or -ketoesters andnitriles in the presence of 10 mol% of copper(II tetrafluoroborate and a stoichiometric amount of acetylchloride. A solution of 10 mol% of Cu(BF42 in acetonitrile provides a convenient reaction medium to carry out athree component reaction under mild conditions

Halogen-bonded network of trinuclear copper(II 4-iodopyrazolate complexes formed by mutual breakdown of chloroform and nanojars

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Stuart A. Surmann

2016-11-01

Full Text Available Crystals of bis(tetrabutylammonium di-μ3-chlorido-tris(μ2-4-iodopyrazolato-κ2N:N′tris[chloridocuprate(II] 1,4-dioxane hemisolvate, (C16H36N2[Cu3(C3H2IN23Cl5]·0.5C4H8O or (Bu4N2[CuII3(μ3-Cl2(μ-4-I-pz3Cl3]·0.5C4H8O, were obtained by evaporating a solution of (Bu4N2[{CuII(μ-OH(μ-4-I-pz}nCO3] (n = 27–31 nanojars in chloroform/1,4-dioxane. The decomposition of chloroform in the presence of oxygen and moisture provides HCl, which leads to the breakdown of nanojars to the title trinuclear copper(II pyrazolate complex, and possibly CuII ions and free 4-iodopyrazole. CuII ions, in turn, act as catalyst for the accelerated decomposition of chloroform, ultimately leading to the complete breakdown of nanojars. The crystal structure presented here provides the first structural description of a trinuclear copper(II pyrazolate complex with iodine-substituted pyrazoles. In contrast to related trinuclear complexes based on differently substituted 4-R-pyrazoles (R = H, Cl, Br, Me, the [Cu3(μ-4-I-pz3Cl3] core in the title complex is nearly planar. This difference is likely a result of the presence of the iodine substituent, which provides a unique, novel feature in copper pyrazolate chemistry. Thus, the iodine atoms form halogen bonds with the terminal chlorido ligands of the surrounding complexes [mean length of I...Cl contacts = 3.48 (1 Å], leading to an extended two-dimensional, halogen-bonded network along (-110. The cavities within this framework are filled by centrosymmetric 1,4-dioxane solvent molecules, which create further bridges via C—H...Cl hydrogen bonds with terminal chlorido ligands of the trinuclear complex not involved in halogen bonding.

Synthesis and structure of dinuclear dimethylene- or 1,4-phenylene-linked bis(decamethyltitanoceneoxide) (Ti-III) complexes

Czech Academy of Sciences Publication Activity Database

Horáček, Michal; Gyepes, R.; Císařová, I.; Kubišta, Jiří; Pinkas, Jiří; Mach, Karel

2010-01-01

Roč. 695, č. 21 (2010), s. 2338-2344 ISSN 0022-328X R&D Projects: GA AV ČR KAN100400701; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : titanium * titanocene * dinuclear complexes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.205, year: 2010

Synthesis, Crystal Structure and DFT Studies of a New Dinuclear Ag(I-Malonamide Complex

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Saied M. Soliman

2018-04-01

Full Text Available The synthesis and structural aspects of a new dinuclear silver (I complex with malonamide type ligand (L is reported. Each Ag ion in the [Ag2L2(NO32]·H2O complex is coordinated to two ligands, L, each acting as a bridged ligand via its two pyridine arms; Ag(I acts as a connector between them. Two types of Ag-ligands close contacts were detected: Ag–N1, Ag–N4 from the two L units, and Ag–O5, Ag—O6 from the two nitrate anions, wherein both the nitrate ions are inside the cage formed by the [Ag2L2] unit. The coordination geometry around each Ag(I is a distorted tetrahedron. The [Ag2L2(NO32] complex units are connected by weak intermolecular C—H…O interactions. The different intermolecular interactions were quantified using Hirshfeld surface analysis. Using two DFT methods (B3LYP and WB97XD, the nature and strength of the Ag–N and Ag–O interactions were described using atoms in molecules (AIM and natural bond orbital (NBO analyses. Topological parameters indicated that the strength of the two Ag–N bonds was similar, while that of the two Ag–O interactions were significantly different. Moreover, the Ag–N interactions have a predominant covalent character, while the Ag–O interactions are mainly ionic. The NBO analysis indicated that the most important anti-bonding Ag-orbital in these interactions has an s-orbital character.

Synthesis and characterization of mononuclear copper(II complex of tetradentate N2S2 donor set and the study of DNA and bovine serum albumin binding

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Sandipan Sarkar

2014-12-01

Full Text Available One mononuclear copper(II complex, containing neutral tetradentate NSSN-type ligands, of formulation [Cu II(L 1Cl]ClO 4 (1, was synthesized and isolated in pure form [where L 1˭ 1,3-bis(3-pyridylmethylthiopropane]. Green-colored copper(II complex was characterized by physicochemical, spectroscopic methods and conductivity measurement. These experimental data matched well with the proposed structure of the complex. Biological activity of the complex (1 toward calf thymus DNA and bovine serum albumin has been examined systematically and groove-binding behavior of the Copper(II complex 1 with calf thymus DNA has been observed from the spectral study.

DNA interactions of dinuclear RuII arene antitumor complexes in cell-free media

Czech Academy of Sciences Publication Activity Database

Nováková, Olga; Nazarov, A.A.; Hartinger, Ch.G.; Keppler, B.K.; Brabec, Viktor

2009-01-01

Roč. 77, č. 3 (2009), s. 364-374 ISSN 0006-2952 R&D Projects: GA MŠk(CZ) LC06030; GA MŠk(CZ) ME08017; GA MŠk(CZ) OC08003; GA AV ČR(CZ) 1QS500040581; GA AV ČR(CZ) KAN200200651 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : dinuclear ruthenium complex * DNA * cross-links Subject RIV: BO - Biophysics Impact factor: 4.254, year: 2009

Preconcentration and extraction of copper(II on activated carbon using ethyl-2-quinolyl-β (p-carboxyphenyl hydrazonedioxo propionate

Directory of Open Access Journals (Sweden)

Mehrorang Ghaedi

2008-12-01

Full Text Available Activated carbon modified method was used for the preconcentration and determination of copper content in real samples such as tap water, wastewater and a synthetic water sample by flame atomic absorption spectrometry. The copper(II was adsorbed quantitatively on activated carbon due to its complexation with ethyl-2-quinolyl-β(p-carboxyphenyl hydrazonedioxo propionate (EQCPDP. The adsorbed copper(II ion on solid phase was eluted quantitatively by using nitric acid. The important parameters such as pH, amount of carrier, flow rate, amount of activated carbon and type and concentration of eluting agent for obtaining maximum recovery were optimized. The method at optimum conditions gives linear concentration range of 0.05-1.0 μg mL-1 of copper(II with correlation coefficient of 0.9994 and the detection limit of 0.99 ng mL-1. The preconcentration leads to enrichment factor of 175 and break through volume of 1750 mL. The method has good tolerance limit of interfering ions and selectivity and it has been successfully applied for determination of copper content in real sample such as blood, wastewater and river sample.

Obtención de mapas de curvas residuales para la síntesis de acetato de butilo

OpenAIRE

Orjuela Londoño, Álvaro; Leiva Lenis, Fernando; Boyacá Mendivelso, Luis Alejandro; Rodríguez Niño, Gerardo; Carballo Suárez, Luis María

2010-01-01

Es este trabajo se adelantó un estudio en la escala de laboratorio de la síntesis acetato de n-butilo en fase líquida (P atm = 560 mmHg), en operación simultánea de reacción y destilación (destilación reactiva batch), utilizando una resina de intercambio catiónico (Lewatit K-2431) como catalizador. Por medio de la construcción experimental de curvas residuales, utilizando diferentes cargas de catalizador, se determinaron las condiciones para las cuales la operación esta limita...

Synchronicity of mononuclear and dinuclear events in homogeneous catalysis. Hydroformylation of cyclopentene using Rh4(CO)12 and HRe(CO)5 as precursors.

Science.gov (United States)

Li, Chuanzhao; Chen, Li; Garland, Marc

2007-10-31

The combined application of two or more metals in homogeneous catalysis can lead to synergistic effects; however, the phenomenological basis for these observations often goes undetermined. The hetero-bimetallic catalytic binuclear elimination reaction, a system involving both mononuclear and dinuclear intermediates, has been repeatedly suggested as a possible mechanism. In the present contribution, the simultaneous application of Rh4(CO)12 and HRe(CO)5 as precursors in the hydroformylation reaction leads to a very strong synergistic rate effect. In situ spectroscopic measurements confirm the presence of both mononuclear and dinuclear intermediates such as RCORh(CO)4 and RhRe(CO)9 in the active system. Moreover, kinetic analysis confirms interconversion of these intermediates as well as their statistical correlation with organic product formation. Specifically, the rate of hydrogen activation by RhRe(CO)9 is exactly equal to the rate of aldehyde formation from binuclear elimination between HRe(CO)5 and RCORh(CO)4 at all reaction conditions studied. Thus the catalytic events involving mononuclear species and those involving dinuclear species are synchronized. In the present experiments, the new topology is orders of magnitude more efficient than the corresponding unicyclic rhodium system.

Copper(II) complexes with 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid: Syntheses, crystal structures and antifungal activities

International Nuclear Information System (INIS)

Xiong, Pingping; Li, Jie; Bu, Huaiyu; Wei, Qing; Zhang, Ruolin; Chen, Sanping

2014-01-01

Reaction of Cu(II) with an asymmetric semi-rigid organic ligand 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid (HL), yielded five compounds, [Cu 0.5 L] n (1), [Cu(HL) 2 Cl 2 ] n (2), [Cu(HL) 2 Cl 2 (H 2 O)] (3), [Cu(L) 2 (H 2 O)] n (4) and [Cu(L)(phen)(HCO 2 )] n (5), which have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. As for compounds 1, 2 and 5, Cu(II) is bridged through HL, Cl - , and formic acid, respectively, featuring 1D chain-structure. In compound 3, Cu(II) with hexahedral coordination sphere is assembled through hydrogen-bonding into 3D supramolecular framework. In compound 4, 1D chain units –Cu–O–Cu–O– are ligand-bridged into a 3D network. All compounds were tested on fungi (Fusarium graminearum, Altemaria solani, Macrophoma kawatsukai, Alternaria alternata and Colletotrichum gloeosporioides). Compound 1 exhibits a better antifungal effect compared to other compounds. An effect of structure on the antifungal activity has also been correlated. - Graphical abstract: Copper(II) compounds with 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid, were prepared, structurally characterized and investigated for antifungal activity. - Highlights: • The title compounds formed by thermodynamics and thermokinetics. • The five compounds show higher inhibition percentage than reactants. • The structure effect on the antifungal activity

Single-molecule magnet behavior in 2,2’-bipyrimidine-bridged dilanthanide complexes

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Wen Yu

2016-01-01

Full Text Available A series of 2,2’-bipyrimidine-bridged dinuclear lanthanide complexes with the general formula [Ln(tmhd3]2bpm (tmhd = 2,2,6,6-tetramethyl-3,5-heptanedionate, bpm = 2,2’-bipyrimidine, Ln = Gd(III, 1; Tb(III, 2; Dy(III, 3; Ho(III, 4 and Er(III, 5 has been synthesized and characterized. Sublimation of [Tb(tmhd3]2bpm onto a Au(111 surface leads to the formation of a homogeneous film with hexagonal pattern, which was studied by scanning tunneling microscopy (STM. The bulk magnetic properties of all complexes have been studied comprehensively. The dynamic magnetic behavior of the Dy(III and Er(III compounds clearly exhibits single molecule magnet (SMM characteristics with an energy barrier of 97 and 25 K, respectively. Moreover, micro-SQUID measurements on single crystals confirm their SMM behavior with the presence of hysteresis loops.

Equilibrios de precipitación. Influencia del pH sobre la solubilidad del acetato de plata. Problema interactivo.

OpenAIRE

Milla González, Miguel

2015-01-01

Se estudia como influye la variación del pH en la solubilidad de una sal cuya parte aniónica es una base débil. Es el caso del acetato de plata. Mediante una animación se muestra el desplazamiento del equilibrio hacia una mayor solubilización. El paso siguiente es encontrar una expresión sencilla que relaciona la solubilidad con el pH y se representa gráficamente dicha función mediante una hoja de cálculo.

Distinctive EPR signals provide an understanding of the affinity of bis-(3-hydroxy-4-pyridinonato) copper(II) complexes for hydrophobic environments.

Science.gov (United States)

Rangel, Maria; Leite, Andreia; Silva, André M N; Moniz, Tânia; Nunes, Ana; Amorim, M João; Queirós, Carla; Cunha-Silva, Luís; Gameiro, Paula; Burgess, John

2014-07-07

In this work we report the synthesis and characterization of a set of 3-hydroxy-4-pyridinone copper(ii) complexes with variable lipophilicity. EPR spectroscopy was used to characterize the structure of copper(ii) complexes in solution, and as a tool to gain insight into solvent interactions. EPR spectra of solutions of the [CuL2] complexes recorded in different solvents reveal the presence of two copper species whose ratio depends on the nature of the solvent. Investigation of EPR spectra in the pure solvents methanol, dimethylsulfoxide, dichloromethane and their 50% (v/v) mixtures with toluene allowed the characterization of two types of copper signals (gzz = 2.30 and gzz = 2.26) whose spin-Hamiltonian parameters are consistent with solvated and non-solvated square-planar copper(ii) complexes. Regarding the potential biological application of ligands and complexes and to get insight into the partition properties in water-membrane interfaces, EPR spectra were also obtained in water-saturated octanol, an aqueous solution buffered at pH = 7.4 and liposome suspensions, for three compounds representative of different hydro-lipophilic balances. Analysis of the EPR spectra obtained in liposomes allowed establishment of the location of the complexes in the water and lipid phases. In view of the results of this work we put forward the use of EPR spectroscopy to assess the affinity of copper(ii) complexes for a hydrophobic environment and also to obtain indirect information about the lipophilicity of the ligands and similar EPR silent complexes.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples.

Science.gov (United States)

Barache, Umesh B; Shaikh, Abdul B; Lokhande, Tukaram N; Kamble, Ganesh S; Anuse, Mansing A; Gaikwad, Shashikant H

2018-01-15

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414nm which remains stable for >48h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5μgmL -1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5μgmL -1 to 17.5μgmL -1 . The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813×10 4 Lmol -1 cm -1 , 0.01996μgcm -2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4'-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples, leafy

RECOVERY OF COPPER(II AND CHROMIUM(III FROM NITRATE MEDIUM WITH SALICYLIDENEANILINE DISSOLVED IN 1-OCTANOL

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A. Guerdouh

2016-05-01

Full Text Available The solvent extraction of copper(II and chromium(III from nitrate medium with salicylideneaniline (HL is studied as a function of various parameters: pH, concentration of salicylideneaniline, contact time and the nature of anoin (nitrate and sulfate in aqueous phase. Chromium(III is not extracted by salicylideneaniline  diluted in 1-octanol. Copper(II is only extracted by salicylideneaniline and it was found that the highest extractability achieved to 95% at pH 4.9, The stoichiometry of the extracted species was determined by using the method of slope analysis. Elemental analysis, UV–vis and IR-spectra were used to confirm the structure. It is found that the copper (II is extracted as CuL2.2H2O Their equilibrium constant, distribution coefficient, percentage extraction (%E and free energy are also calculated.

An efficient, cost effective, sensing behaviour liquid-liquid extraction and spectrophotometric determination of copper(II) incorporated with 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole: Analysis of food samples, leafy vegetables, fertilizers and environmental samples

Science.gov (United States)

Barache, Umesh B.; Shaikh, Abdul B.; Lokhande, Tukaram N.; Kamble, Ganesh S.; Anuse, Mansing A.; Gaikwad, Shashikant H.

2018-01-01

The aim of the present work is to develop an efficient, simple and selective moreover cost-effective method for the extractive spectrophotometric determination of copper(II) by using the Schiff base 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole [CBIMMT]. This chromogenic reagent forms a yellow coloured complex with copper(II) in acetate buffer at pH 4.2. The copper(II) complex with ligand is instantly extracted into chloroform and shows a maximum absorbance at 414 nm which remains stable for > 48 h. The composition of extracted complex is found to be 1:2 [copper(II): reagent] which was ascertained using Job's method of continuous variation, mole ratio method and slope ratio method. Under optimal conditions, the copper(II) complex in chloroform adheres to Beer's law up to 17.5 μg mL- 1 of copper(II). The optimum concentration range obtained from Ringbom's plot is from 5 μg mL- 1 to 17.5 μg mL- 1. The molar absorptivity, Sandell's sensitivity and enrichment factor of the extracted copper(II) chelate are 0.33813 × 104 L mol- 1 cm- 1, 0.01996 μg cm- 2 and 2.49 respectively. In the extraction of copper(II), several affecting factors including the solution pH, ligand concentration, equilibrium time, effect of foreign ions are optimized. The interfering effects of various cations and anions were also studied and use of masking agents enhances the selectivity of the method. The chromogenic sulphur containing reagent, 4-(4‧-chlorobenzylideneimino)-3-methyl-5-mercapto-1, 2, 4-triazole has been synthesized in a single step with high purity and yield. The synthesized reagent has been successfully applied first time for determination of copper(II). The reagent forms stable chelate with copper(II) in buffer medium instantly and quantitatively extracted in chloroform within a minute. The method is successfully applied for the determination of copper(II) in various synthetic mixtures, complexes, fertilizers, environmental samples such as food samples

Synthesis, structure, and magnetic properties of two 1-D helical coordination polymeric Cu(II) complexes

Science.gov (United States)

Bian, He-Dong; Yang, Xiao-E.; Yu, Qing; Chen, Zi-Lu; Liang, Hong; Yan, Shi-Ping; Liao, Dai-Zheng

2008-01-01

Two helical coordination polymeric copper(II) complexes bearing amino acid Schiff bases HL or HL', which are condensed from 2-hydroxy-1-naphthaldehyde with 2-aminobenzoic acid or L-valine, respectively, have been prepared and characterised by X-ray crystallography. In [CuL] n ( 1) the copper(II) atoms are bridged by syn- anti carboxylate groups giving infinite 1-D right-handed helical chains which are further connected by weak C-H⋯Cu interactions to build a 2-D network. While in [CuL'] n ( 2) the carboxylate group acts as a rare monatomic bridge to connect the adjacent copper(II) atoms leading to the formation of a left-handed helical chain. Magnetic susceptibility measurements indicate that 1 exhibits weak ferromagnetic interactions whereas an antiferromagnetic coupling is established for 2. The magnetic behavior can be satisfactorily explained on the basis of the structural data.

Glaucoma persistente secundário à injeção subtenoniana posterior de acetato de triancinolona (Kenalog®: relato de casos

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Finamor Luciana Peixoto

2003-01-01

Full Text Available OBJETIVO: Descrever 3 casos de crianças submetidas à injeção subtenoniana posterior de acetato de triancinolona (Kenalog® 40mg para tratamento de uveíte intermediária, com desenvolvimento de glaucoma secundário refratário. MÉTODOS: Relato de caso. RESULTADOS: Três crianças com diagnóstico de uveíte intermediária, submetidas à injeção subtenoniana posterior de acetato de triancinolona para tratamento de inflamação vítrea crônica e/ou edema macular cistóide, desenvolveram glaucoma refratário e foram submetidos à excisão cirúrgica do corticóide de depósito e/ou cirurgia filtrante para controle da pressão intra-ocular (PIO. CONCLUSÃO: Corticóide de depósito periocular pode representar alto risco para desenvolvimento de glaucoma secundário, de difícil controle em crianças. Excisão cirúrgica do corticóide de depósito pode resultar em controle da PIO, porém, em alguns casos, a realização de cirurgia filtrante é necessária.

Mono and dinuclear iridium, rhodium and ruthenium complexes containing chelating carboxylato pyrazine ligands: Synthesis, molecular structure and electrochemistry

Czech Academy of Sciences Publication Activity Database

Govindaswamy, P.; Therrien, B.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

2007-01-01

Roč. 692, č. 8 (2007), s. 1661-1671 ISSN 0022-328X R&D Projects: GA MŠk LC510; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : dinuclear complexes * iridium * rhodium * ruthenium * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 2.168, year: 2007

Synthesis, X-ray crystal structures, and phosphate ester cleavage properties of bis(2-pyridylmethyl)amine copper(II) complexes with guanidinium pendant groups.

Science.gov (United States)

Belousoff, Matthew J; Tjioe, Linda; Graham, Bim; Spiccia, Leone

2008-10-06

Three new derivatives of bis(2-pyridylmethyl)amine (DPA) featuring ethylguanidinium (L (1)), propylguanidinium (L (2)), or butylguanidinium (L (3)) pendant groups have been prepared by the reaction of N, N- bis(2-pyridylmethyl)alkane-alpha,omega-diamines with 1 H-pyrazole-1-carboxamidine hydrochloride. The corresponding mononuclear copper(II) complexes were prepared by reacting the ligands with copper(II) nitrate and were isolated as [Cu(LH (+))(OH 2)](ClO 4) 3. xNaClO 4. yH 2O ( C1: L = L (1), x = 2, y = 3; C2: L = L (2), x = 2, y = 4; C3: L = L (3), x = 1, y = 0) following cation exchange purification. Recrystallization yielded crystals of composition [Cu(LH (+))(X)](ClO 4) 3.X ( C1': L = L (1), X = MeOH; C2': L = L (2), X = H 2O; C3': L = L (3), X = H 2O), which were suitable for X-ray crystallography. The crystal structures of C1', C2', and C3' indicate that the DPA moieties of the ligands coordinate to the copper(II) centers in a meridional fashion, with a water or methanol molecule occupying the fourth basal position. Weakly bound perchlorate anions located in the axial positions complete the distorted octahedral coordination spheres. The noncoordinating, monoprotonated guanidinium groups project away from the Cu(II)-DPA units and are involved in extensive charge-assisted hydrogen-bonding interactions with cocrystallized water/methanol molecules and perchlorate anions within the crystal lattices. The copper(II) complexes were tested for their ability to promote the cleavage of two model phosphodiesters, bis( p-nitrophenyl)phosphate (BNPP) and uridine-3'- p-nitrophenylphosphate (UpNP), as well as supercoiled plasmid DNA (pBR 322). While the presence of the guanidine pendants was found to be detrimental to BNPP cleavage efficiency, the functionalized complexes were found to cleave plasmid DNA and, in some cases, the model ribose phosphate diester, UpNP, at a faster rate than the parent copper(II) complex of DPA.

Influência do desenvolvimento etário e da suplementação com vitamina E (acetato de DL-alfa-tocoferol no metabolismo oxidativo dos neutrófilos de bovinos da raça Holandesa (Bos taurus

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Joselito Nunes Costa

2004-10-01

Full Text Available O presente trabalho teve por objetivo analisar a influência do desenvolvimento etário e da suplementação com acetato de DL-alfa-tocoferol sobre o metabolismo oxidativo de neutrófilos, em bovinos da raça holandesa, no período do nascimento até os 150 dias de idade. Foram utilizados 20 bezerros divididos em dois grupos de dez animais. Os animais do grupo Tratamento receberam 2000UI de acetato de DL-alfa-tocoferol, por via intramuscular, ao nascimento, aos 15, 30, 60, 90 e 120 dias de idade, sendo o outro o grupo Controle, que não recebeu qualquer suplementação. Em ambos os grupos, o metabolismo oxidativo dos neutrófilos demonstrou pouca atividade durante os primeiros 60 dias de vida, sendo indicativo da ineficiência deste importante mecanismo bactericida. Não foi observado efeito significativo da administração do acetato de DL-alfa-tocoferol sobre o metabolismo oxidativo de neutrófilos.

New cobalt-mediated radical polymerization (CMRP of methyl methacrylate initiated by two single-component dinuclear β-diketone cobalt (II catalysts.

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Feng Bao

Full Text Available Two dinuclear cobalt complexes based on bis-diketonate ligands (ligand 1: 3,3'-(1,3-phenylenebis(1-phenylpropane-1,3-dione; ligand 2: 3,3'-(1,4-phenylenebis(1-phenylpropane-1,3-dione were successfully synthesized. The two neutral catalysts all showed satisfactory activities in the cobalt-mediated radical polymerization (CMRP of methyl methacrylate (MMA with the common initiator of azodiisobutyronitrile (AIBN. The resulting polymerizations have all of the characteristics of a living polymerization and displayed linear semilogarithmic kinetic plots, a linear correlation between the number-average molecular weight and the monomer conversion, and low polydispersities. Mono- or dicomponent low polydispersity polymers could be obtained by using the two dinuclear catalysts under proper reaction conditions. All these improvements facilitate the implementation of the acrylate CMRP and open the door to the scale-up of the syntheses and applications of the multicomponent low polydispersity polymers.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

... two indole thiohydrazide arms forming SNONS coordinating sites. NMR and IR spectral studies show that the ligand exists in thioketo form. Each Zn ion in the dinuclear core is in tetrahedral environment with endogenous phenolate bridging and exogenous acetate bridging. The zinc complex in DMF exhibits fluorescence.

Copper(II) complexes with 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid: Syntheses, crystal structures and antifungal activities

Energy Technology Data Exchange (ETDEWEB)

Xiong, Pingping [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi' an 710069 (China); Li, Jie [Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), Shaanxi Provincial Key Laboratory of Biotechnology, Xi' an 710069 (China); Bu, Huaiyu, E-mail: 7213792@qq.com [Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), Shaanxi Provincial Key Laboratory of Biotechnology, Xi' an 710069 (China); Wei, Qing [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi' an 710069 (China); Zhang, Ruolin [Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), Shaanxi Provincial Key Laboratory of Biotechnology, Xi' an 710069 (China); Chen, Sanping, E-mail: sanpingchen@126.com [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi' an 710069 (China)

2014-07-01

Reaction of Cu(II) with an asymmetric semi-rigid organic ligand 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid (HL), yielded five compounds, [Cu{sub 0.5}L]{sub n} (1), [Cu(HL){sub 2}Cl{sub 2}]{sub n} (2), [Cu(HL){sub 2}Cl{sub 2}(H{sub 2}O)] (3), [Cu(L){sub 2}(H{sub 2}O)]{sub n} (4) and [Cu(L)(phen)(HCO{sub 2})]{sub n} (5), which have been fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. As for compounds 1, 2 and 5, Cu(II) is bridged through HL, Cl{sup -}, and formic acid, respectively, featuring 1D chain-structure. In compound 3, Cu(II) with hexahedral coordination sphere is assembled through hydrogen-bonding into 3D supramolecular framework. In compound 4, 1D chain units –Cu–O–Cu–O– are ligand-bridged into a 3D network. All compounds were tested on fungi (Fusarium graminearum, Altemaria solani, Macrophoma kawatsukai, Alternaria alternata and Colletotrichum gloeosporioides). Compound 1 exhibits a better antifungal effect compared to other compounds. An effect of structure on the antifungal activity has also been correlated. - Graphical abstract: Copper(II) compounds with 4-(1H-1, 2, 4-trizol-1-ylmethyl) benzoic acid, were prepared, structurally characterized and investigated for antifungal activity. - Highlights: • The title compounds formed by thermodynamics and thermokinetics. • The five compounds show higher inhibition percentage than reactants. • The structure effect on the antifungal activity.

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

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Christian Benkhäuser

2015-05-01

Full Text Available A Tröger's base-derived racemic bis(1,10-phenanthroline ligand (rac-1 and a bis(2,2'-bipyridine ligand with a central 1,3-diethynylbenzene unit 2 were synthesized. Each of these ligands acts as a multivalent entity for the binding of two copper(I ions. Upon coordination to the metal ions these two ligands undergo selective self-assembly into heteroleptic dinuclear metallosupramolecular kites in a high-fidelity social self-sorting manner as evidenced by NMR spectroscopy and mass spectrometry.

A novel aggregation induced emission active cyclometalated Ir(III) complex as a luminescent probe for detection of copper(II) ion in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Shen, Wei; Yan, Liqiang; Tian, Wenwen; Cui, Xia; Qi, Zhengjian, E-mail: qizhengjian@seu.edu.cn; Sun, Yueming, E-mail: sun@seu.edu.cn

2016-09-15

We report the synthesis and characterization of a novel aggregation induced emission (AIE) active cyclometalated Ir(III) complex, namely [Ir(dfppy){sub 2}(phen-DPA)]PF{sub 6}, where dfppy and phen-DPA represent 2-(2,4-difluorophenyl)pyridine and 2-(bis(pyridin-2-ylmethyl)amino)-N-(1,10-phenanthrolin-5-yl)acetamide, respectively. The complex showed remarkable selectivity for copper(II) in aqueous solution over other competitive ions. Furthermore, this sensor showed a rapid and reversible response to copper(II) in aqueous solution with a detection limit of 65 nM.

Synthesis of superheavy elements and dinuclear-system concept of compound-nucleus formation

Energy Technology Data Exchange (ETDEWEB)

Antonenko, N.V.; Adamian, G.G.; Cherepanov, E.A. [Joint Institute for Nuclear Research, Dubna (Russian Federation)] [and others

1996-12-31

Dinuclear system concept is applied to the analysis of reactions used for the synthesis of elements with Z = 110, 112, 114, and 116. The inner fusion barriers obtained for these reactions are in good agreement with the experimental estimations resulted from the excitation energies of compound nuclei. A model is suggested for the calculation of the competition between complete fusion and quasifission in reactions with heavy nuclei. The fusion rate through the inner fusion barrier in mass asymmetry is found by using the multidimensional Kramers-type stationary solution of the Fokker-Planck equation. The influence of dissipative effects on the dynamics of nuclear fusion is considered.

Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy.

Science.gov (United States)

Hayes, Dugan; Kohler, Lars; Hadt, Ryan G; Zhang, Xiaoyi; Liu, Cunming; Mulfort, Karen L; Chen, Lin X

2018-01-28

The kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(i) bis(phenanthroline)/ruthenium(ii) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(i)-Ru(ii) analogs of the homodinuclear Cu(i)-Cu(i) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These results suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations.

Strong exchange and magnetic blocking in N₂³⁻-radical-bridged lanthanide complexes.

Science.gov (United States)

Rinehart, Jeffrey D; Fang, Ming; Evans, William J; Long, Jeffrey R

2011-05-22

Single-molecule magnets approach the ultimate size limit for spin-based devices. These complexes can retain spin information over long periods of time at low temperature, suggesting possible applications in high-density information storage, quantum computing and spintronics. Notably, the success of most such applications hinges upon raising the inherent molecular spin-inversion barrier. Although recent advances have shown the viability of lanthanide-containing complexes in generating large barriers, weak or non-existent magnetic exchange coupling allows fast relaxation pathways that mitigate the full potential of these species. Here, we show that the diffuse spin of an N(2)(3-) radical bridge can lead to exceptionally strong magnetic exchange in dinuclear Ln(III) (Ln = Gd, Dy) complexes. The Gd(III) congener exhibits the strongest magnetic coupling yet observed for that ion, while incorporation of the high-anisotropy Dy(III) ion gives rise to a molecule with a record magnetic blocking temperature of 8.3 K at a sweep rate of 0.08 T s(-1).

Ferromagnetic dinuclear mixed-valence Mn(II)/Mn(III) complexes: building blocks for the higher nuclearity complexes. structure, magnetic properties, and density functional theory calculations.

Science.gov (United States)

Hänninen, Mikko M; Välivaara, Juha; Mota, Antonio J; Colacio, Enrique; Lloret, Francesc; Sillanpää, Reijo

2013-02-18

A series of six mixed-valence Mn(II)/Mn(III) dinuclear complexes were synthesized and characterized by X-ray diffraction. The reactivity of the complexes was surveyed, and structures of three additional trinuclear mixed-valence Mn(III)/Mn(II)/Mn(III) species were resolved. The magnetic properties of the complexes were studied in detail both experimentally and theoretically. All dinuclear complexes show ferromagnetic intramolecular interactions, which were justified on the basis of the electronic structures of the Mn(II) and Mn(III) ions. The large Mn(II)-O-Mn(III) bond angle and small distortion of the Mn(II) cation from the ideal square pyramidal geometry were shown to enhance the ferromagnetic interactions since these geometrical conditions seem to favor the orthogonal arrangement of the magnetic orbitals.

Atribuição dos deslocamentos químicos dos átomos de ¹H e 13C do acetato de acantoaustralida

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Lúcia R. Rocha Martins

Full Text Available Do extrato hidroetanólico das partes aéreas de Acanthospermum australe (Asteraceae foram identificados uma lactona diterpênica, o acetato de acantoaustralida (1 e dois flavonoides: quercetina (2 e crisosplenol D (3. As estruturas foram identificadas através de técnicas espectroscópicas de RMN de ¹H e 13C, gHSQC, gHMBC, TOCSY, gNOESY, EM e pela comparação com dados da literatura.

Bis[μ-2-(aminosulfanylpyridine(1−]bis[(η5-pentamethylcyclopentadienyliridium(III] diiodide

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Yusuke Sekioka

2009-10-01

Full Text Available In the title dinuclear iridium(III complex, [Ir2(C10H152(C5H5N2S2]I2, the iridium(III atoms are bridged by 2-(aminosulfanylpyridine(1− [(2-pySNH] ligands in a μ-(2-pySNH-κ2N(py,N(NH:κN(NH mode. The dinuclear complex cation lies on a crystallographic inversion center, resulting in a planar Ir2N2 ring with an Ir—N(py bond length of 2.085 (9 Å and bridging Ir—N(NH bonds of 2.110 (9 and 2.113 (9 Å. The two (2-pyS units have mutually anti configurations with respect to the Ir2N2 ring

Crystal structure of di-μ-chlorido-bis[chloridobis(1,2-dimethyl-5-nitro-1H-imidazole-κN3copper(II] acetonitrile disolvate

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Patrick J. Quinlivan

2016-11-01

Full Text Available 1,2-Dimethyl-5-nitroimidazole (dimetridazole, dimet is a compound that belongs to a class of nitroimidazole drugs that are effective at inhibiting the activity of certain parasites and bacteria. However, there are few reports that describe structures of compounds that feature metals complexed by dimet. Therefore, we report here that dimet reacts with CuCl2·H2O to yield a chloride-bridged copper(II dimer, [Cu2Cl4(C5H7N3O24] or [Cu(μ-ClCl(dimet2]2. In this molecule, the CuII ions are coordinated in an approximately trigonal–bipyramidal manner, and the molecule lies across an inversion center. The dihedral angle between the imidazole rings in the asymmetric unit is 4.28 (7°. Compared to metronidazole, dimetridazole lacks the hydroxyethyl group, and thus cannot form intermolecular O...H hydrogen-bonding interactions. Instead, [Cu(μ-ClCl(dimet2]2 exhibits weak intermolecular interactions between the hydrogen atoms of C—H groups and (i oxygen in the nitro groups, and (ii the terminal and bridging chloride ligands. The unit cell contains four disordered acetonitrile molecules. These were modeled as providing a diffuse contribution to the overall scattering by SQUEEZE [Spek (2015. Acta Cryst. C71, 9–18], which identified two voids, each with a volume of 163 Å3 and a count of 46 electrons, indicative of a total of four acetonitrile molecules. These acetonitrile molecules are included in the chemical formula to give the expected calculated density and F(000.

Metal-Organic Framework of Lanthanoid Dinuclear Clusters Undergoes Slow Magnetic Relaxation

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Hikaru Iwami

2017-01-01

Full Text Available Lanthanoid metal-organic frameworks (Ln-MOFs can adopt a variety of new structures due to the large coordination numbers of Ln metal ions, and Ln-MOFs are expected to show new luminescence and magnetic properties due to the localized f electrons. In particular, some Ln metal ions, such as Dy(III and Tb(III ions, work as isolated quantum magnets when they have magnetic anisotropy. In this work, using 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid (H3TATB as a ligand, two new Ln-MOFs, [Dy(TATB(DMF2] (1 and [Tb(TATB(DMF2] (2, were obtained. The Ln-MOFs contain Ln dinuclear clusters as secondary building units, and 1 underwent slow magnetic relaxation similar to single-molecule magnets.

Electronic and magnetic properties of infinite 1D chains of paddlewheel carboxylates M2(COOR)4 (M = Mo, W, Ru, Rh, Ir, Cu)

KAUST Repository

Peskov, Maxim; Miao, Xiaohe; Heryadi, Dodi; Eppinger, Jö rg; Schwingenschlö gl, Udo

2013-01-01

Dinuclear complexes of transition metals bridged by four carboxylate-groups are examples of stable atomic configurations serving as fundamental building blocks of catalysts and prototypical molecular electronic devices. The electronic structure

High stability and biological activity of the copper(II) complexes of alloferon 1 analogues containing tryptophan.

Science.gov (United States)

Kadej, Agnieszka; Kuczer, Mariola; Czarniewska, Elżbieta; Urbański, Arkadiusz; Rosiński, Grzegorz; Kowalik-Jankowska, Teresa

2016-10-01

Copper(II) complex formation processes between the alloferon 1 (Allo1) (HGVSGHGQHGVHG) analogues where the tryptophan residue is introducing in the place His residue H1W, H6W, H9W and H12W have been studied by potentiometric, UV-visible, CD and EPR spectroscopic, and MS methods. For all analogues of alloferon 1 complex speciation have been obtained for a 1:1 metal-to-ligand molar ratio and 2:1 of H1W because of precipitation at higher (2:1, 3:1 and 4:1) ratios. At physiological pH7.4 and a 1:1 metal-to-ligand molar ratio the tryptophan analogues of alloferon 1 form the CuH -1 L and/or CuH -2 L complexes with the 4N binding mode. The introduction of tryptophan in place of histidine residues changes the distribution diagram of the complexes formed with the change of pH and their stability constants compared to the respective substituted alanine analogues of alloferon 1. The CuH -1 L, CuH -2 L and CuH -3 L complexes of the tryptophan analogues are more stable from 1 to 5 log units in comparison to those of the alanine analogues. This stabilization of the complexes may result from cation(Cu(II))-π and indole/imidazole ring interactions. The induction of apoptosis in vivo, in Tenebrio molitor cells by the ligands and their copper(II) complexes at pH7.4 was studied. The biological results show that copper(II) ions in vivo did not cause any apparent apoptotic features. The most active were the H12W peptide and Cu(II)-H12W complex formed at pH7.4. Copyright © 2016 Elsevier Inc. All rights reserved.

Improving the Response of Copper(II) Selective PVC Membrane Electrode by Modification of N2S2 Donor Ligand.

Science.gov (United States)

Brinić, Slobodan; Buzuk, Marijo; Generalić, Eni; Bralić, Marija

2010-06-01

S,S'-bis(2-aminophenyl)ethanebis(thioate), (APhET), is reported as N2S2 ligand which form chelate with copper of high stability as compared to the other metals. Two modification of APhET, simpler 1,2-di-(o-aminophenylthio)ethane (DAPhTE), and the complex one 1,2-di-(o-salicylaldiminophenylthio)ethane (SAPhTE), were examined as the active material for copper(II) ion selective PVC membrane electrodes, and observed results are correlated. The obtained results with DAPhTE based electrodes show that only coordination abilities of ligand are insufficient for preparing the efficient membrane material. On the other hand, the results that are achieved with electrodes based on SAPhTE actuate interaction of ligand with polymer membrane matrix and necessity of ionophore immobilization in membrane. Optimized SAPhTE based membrane electrode has a linear range down to 10-6 mol L-1, with slope of 27.0 mV per decade, very rapid response time (under 5 seconds) and detection limit of 5.1 × 10-7 mol L-1. Such electrode is suitable for determination of copper(II) in analytical measurements by direct potentiometry and in potentiometric titrations, within pH between 2 and 7. The electrode is selective for copper(II) ions over a large number of metal ions, with the exception on Hg2+ ion when is present in concentrations above 2 × 10-5 mol L-1.

Synthesis, characterization and catalytic oxidation properties of multi-wall carbon nanotubes with a covalently attached copper(II) salen complex

Science.gov (United States)

Salavati-Niasari, Masoud; Bazarganipour, Mehdi

2009-06-01

Hydroxyl functionalized copper(II) Schiff-base, N,N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diaminecopper(II), [Cu((OH) 2-salen)], has been covalently anchored on modified MWCNTs. The new modified MWCNTs ([Cu((OH) 2-salen)]-MWCNTs) have been characterized by TEM, thermal analysis, XRD, XPS, UV-vis, DRS, FT-IR spectroscopy and elemental analysis. The modified copper(II) MWCNTs solid was used to affect the catalytic oxidation of ethylbenzene with tert-butylhydroperoxide as the oxidant at 333 K. The system is truly heterogeneous (no leaching observed) and reusable (no decrease in activity) in three consecutive runs. Acetophenone was the major product though small amounts of o- and p-hydroxyacetophenones were also formed revealing that C-H bond activation takes place both at benzylic and aromatic ring carbon atoms. Ring hydroxylation was more over the "neat" complexes than over the encapsulated complexes.

Flotation of traces of silver and copper(II) ions with a methyl cellosolve solution of dithizone.

Science.gov (United States)

Hiraide, M; Mizuike, A

1975-06-01

Microgram quantities of silver and copper(II) ions in aqueous solutions are collected on dithizone precipitates, which are then floated with the aid of small nitrogen bubbles. This separation technique has been successfully applied to the atomic-absorption spectrophotometric determination of down to a tenth ppm of silver and copper in high-purity lead and zinc metals.

Mono and dinuclear rhodium, iridium and ruthenium complexes containing chelating 2,2´-bipyrimidine ligands: Synthesis, molecular structure, electrochemistry and catalytic properties

Czech Academy of Sciences Publication Activity Database

Govindaswamy, P.; Canivet, J.; Therrien, B.; Süss-Fink, G.; Štěpnička, P.; Ludvík, Jiří

2007-01-01

Roč. 692, č. 17 (2007), s. 3664-3675 ISSN 0022-328X R&D Projects: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503 Keywords : arene ligands * electrochemistry * dinuclear complexes * transfer hydrogenation Subject RIV: CG - Electrochemistry Impact factor: 2.168, year: 2007

Cyanide-limited complexation of molybdenum(III): synthesis of octahedral [Mo(CN)(6)](3-) and cyano-bridged [Mo(2)(CN)(11)](5-).

Science.gov (United States)

Beauvais, Laurance G; Long, Jeffrey R

2002-03-13

Octahedral coordination of molybdenum(III) is achieved by limiting the amount of cyanide available upon complex formation. Reaction of Mo(CF(3)SO(3))(3) with LiCN in DMF affords Li(3)[Mo(CN)(6)] x 6DMF (1), featuring the previously unknown octahedral complex [Mo(CN)(6)](3-). The complex exhibits a room-temperature moment of mu(eff) = 3.80 mu(B), and assignment of its absorption bands leads to the ligand field parameters Delta(o) = 24800 cm(-1) and B = 247 cm(-1). Further restricting the available cyanide in a reaction between Mo(CF(3)SO(3))(3) and (Et(4)N)CN in DMF, followed by recrystallization from DMF/MeOH, yields (Et(4)N)(5)[Mo(2)(CN)(11)] x 2DMF x 2MeOH (2). The dinuclear [Mo(2)(CN)(11)](5-) complex featured therein contains two octahedrally coordinated Mo(III) centers spanned by a bridging cyanide ligand. A fit to the magnetic susceptibility data for 2, gives J = -113 cm(-1) and g = 2.33, representing the strongest antiferromagnetic coupling yet observed through a cyanide bridge. Efforts to incorporate these new complexes in magnetic Prussian blue-type solids are ongoing.

Gold chloride clusters with Au(III) and Au(I) probed by FT-ICR mass spectrometry and MP2 theory.

Science.gov (United States)

Lemke, Kono H

2014-05-07

Microsolvated clusters of gold chloride are probed by electrospray ionization mass spectrometry (ESI-MS) and scalar relativistic electronic structure calculations. Electrospray ionization of aqueous AuCl3 leads to mononuclear clusters of types [AuCl2](+)(H2O)n (n = 0-4), [AuOHCl](+)(H2O)n (n = 0-1) and [AuCl2](+)(HCl)2(H2O)n (n = 0-4). In addition, strong ion signals due to dinuclear [Au2Cl5-xOHx](+)(H2O)n (x = 0-1) are present in ESI mass spectra of aqueous AuCl3, with the abundance of individual dinuclear species controlled by the concentration-dependent variation of the precursor complexes [AuCl2-xOHx](+)(H2O)n and AuCl3. Equilibrium structures, energies and thermodynamic properties of mono- and dinuclear gold clusters have been predicted using MP2 and CCSD(T) theory, and these data have been applied to examine the influence of microsolvation on cluster stability. Specifically, results from CCSD(T) calculations indicate that non-covalently bound ion-neutral complexes Au(+)(Cl2)(H2O)n, with formal Au(I), are the dominant forms of mononuclear gold with n = 0-2, while higher hydrates (n > 2) are covalently bound [AuCl2](+)(H2O)n complexes in which gold exists as Au(III). MP2 calculations show that the lowest energy structure of dinuclear gold is an ion-molecule cluster [Au2Cl(Cl2)2](+) consisting of a single-bridged digold-chloronium ion bound end-on to two dichlorine ligands, with two higher energy isomers, single-bridged [Au2Cl3(Cl2)](+) and double-bridged [Au2Cl5](+) clusters. Finally, AuAu interactions in the singly-bridged clusters [Au2Cl(Cl2)2](+)(H2O)n and [Au2Cl3(Cl2)](+)(H2O)n are examined employing a wide range of computational tools, including natural bond order (NBO) analysis and localized orbital locator (LOL) profiles.

Synthesis, catalytic and biological activity of novel dinuclear copper complex with Schiff base

Institute of Scientific and Technical Information of China (English)

WEI Danyi; LI Ning; LU Gui; YAO Kemin

2006-01-01

A novel dinuclear copper complex with tetraglycol aldehyde-phenylalanine Schiff base has been synthesized. It was characterized and formulated as [Cu2L(NO3)]NO3 by elemental analysis,magnetic susceptibility, TG-DTA, IR, EPR and 1H NMR spectra. The obtained complex can be used as a good catalyst for the polymerization of methyl methacrylate (MMA). The optimum polymerization conditions are: MMNcatalyst = 500 (molar ratio); [catalyst] = 7.5×10-3 mol. L-1; dioxane as solvent;80℃; 6 h. Polymethyl methacrylate (PMMA) with 80% conversion, 7.2×105 viscosity-average molecular weight and 60.5% syndiotacticity was obtained. This complex has also been shown to play an important role in scavenging O-·2.

Synthesis and antimalarial activity of metal complexes of cross-bridged tetraazamacrocyclic ligands.

Science.gov (United States)

Hubin, Timothy J; Amoyaw, Prince N-A; Roewe, Kimberly D; Simpson, Natalie C; Maples, Randall D; Carder Freeman, TaRynn N; Cain, Amy N; Le, Justin G; Archibald, Stephen J; Khan, Shabana I; Tekwani, Babu L; Khan, M O Faruk

2014-07-01

Using transition metals such as manganese(II), iron(II), cobalt(II), nickel(II), copper(II), and zinc(II), several new metal complexes of cross-bridged tetraazamacrocyclic chelators namely, cyclen- and cyclam-analogs with benzyl groups, were synthesized and screened for in vitro antimalarial activity against chloroquine-resistant (W2) and chloroquine-sensitive (D6) strains of Plasmodium falciparum. The metal-free chelators tested showed little or no antimalarial activity. All the metal complexes of the dibenzyl cross-bridged cyclam ligand exhibited potent antimalarial activity. The Mn(2+) complex of this ligand was the most potent with IC50s of 0.127 and 0.157μM against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) P. falciparum strains, respectively. In general, the dibenzyl hydrophobic ligands showed better anti-malarial activity compared to the activity of monobenzyl ligands, potentially because of their higher lipophilicity and thus better cell penetration ability. The higher antimalarial activity displayed by the manganese complex for the cyclam ligand in comparison to that of the cyclen, correlates with the larger pocket of cyclam compared to that of cyclen which produces a more stable complex with the Mn(2+). Few of the Cu(2+) and Fe(2+) complexes also showed improvement in activity but Ni(2+), Co(2+) and Zn(2+) complexes did not show any improvement in activity upon the metal-free ligands for anti-malarial development. Published by Elsevier Ltd.

Synthesis, characterization, and antimicrobial activity of silver(I) and copper(II) complexes of phosphate derivatives of pyridine and benzimidazole.

Science.gov (United States)

Kalinowska-Lis, Urszula; Szewczyk, Eligia M; Chęcińska, Lilianna; Wojciechowski, Jakub M; Wolf, Wojciech M; Ochocki, Justyn

2014-01-01

Two silver(I) complexes--[Ag(4-pmOpe)]NO₃}(n) and [Ag(2-bimOpe)₂]NO₃--and three copper(II) complexes--[Cu₄Cl₆O(2-bimOpe)₄], [CuCl₂(4-pmOpe)₂], and [CuCl₂(2-bis(pm)Ope]--were synthesized by reaction of silver(I) nitrate or copper(II) chloride with phosphate derivatives of pyridine and benzimidazole, namely diethyl (pyridin-4-ylmethyl)phosphate (4-pmOpe), 1H-benzimidazol-2-ylmethyl diethyl phosphate (2-bimOpe), and ethyl bis(pyridin-2-ylmethyl)phosphate (2-bis(pm)Ope). These compounds were characterized by ¹H, ¹³C, and ³¹P NMR as well as IR spectroscopy, elemental analysis, and ESIMS spectrometry. Additionally, molecular and crystal structures of {[Ag(4-pmOpe)]NO₃}n and [Cu₄Cl₆O(2-bimOpe)₄] were determined by single-crystal X-ray diffraction analysis. The antimicrobial profiles of synthesized complexes and free ligands against test organisms from the ATCC and clinical sources were determined. Silver(I) complexes showed good antimicrobial activities against Candida albicans strains (MIC values of ∼19 μM). [Ag(2-bimOpe)₂]NO₃ was particularly active against Pseudomonas aeruginosa and methicillin-resistant Staphylococcus epidermidis, with MIC values of ∼5 and ∼10 μM, respectively. Neither copper(II) complexes nor the free ligands inhibited the growth of test organisms at concentrations below 500 μg mL⁻¹. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterisation of spin-waves in copper(II) deuteroformate tetradeuterate: A square ¤S¤=1/2 Heisenberg antiferromagnet

DEFF Research Database (Denmark)

Clarke, S.J.; Harrison, A.; Mason, T.E.

1999-01-01

Copper(II) formate tetrahydrate (CFTH) is a model square S = 1/2 Heisenberg antiferromagnet with T-N = 16.54 +/- 0.05 K. The dispersion of spin-waves in the magnetic layers of a fully deuterated sample of this material has been mapped at 4.3 K by inelastic neutron scattering from the zone centre ...

Synthesis and characterization of iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes of salicylidene-N-anilinoacetohydrazone (H2L1) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H2L2).

Science.gov (United States)

AbouEl-Enein, S A; El-Saied, F A; Kasher, T I; El-Wardany, A H

2007-07-01

Salicylidene-N-anilinoacetohydrazone (H(2)L(1)) and 2-hydroxy-1-naphthylidene-N-anilinoacetohydrazone (H(2)L(2)) and their iron(III), manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) complexes have been synthesized and characterized by IR, electronic spectra, molar conductivities, magnetic susceptibilities and ESR. Mononuclear complexes are formed with molar ratios of 1:1, 1:2 and 1:3 (M:L). The IR studies reveal various modes of chelation. The electronic absorption spectra and magnetic susceptibility measurements show that the iron(III), nickel(II) and cobalt(II) complexes of H(2)L(1) have octahedral geometry. While the cobalt(II) complexes of H(2)L(2) were separated as tetrahedral structure. The copper(II) complexes have square planar stereochemistry. The ESR parameters of the copper(II) complexes at room temperature were calculated. The g values for copper(II) complexes proved that the Cu-O and Cu-N bonds are of high covalency.

Template synthesis of poly aza macrocyclic copper(II) and nickel(II) complexes: Spectral characterization and antimicrobial studies

Energy Technology Data Exchange (ETDEWEB)

Gurumoorthy, P.; Ravichandran, J.; Kaliur Rahiman, A. [The New College, Chennai (India); Karthikeyan, N.; Palani, P. [Univ. of Madras, Chennai (India)

2012-07-15

The template synthesis of copper(II) and nickel(II) complexes derived from 2,6-diformyl-4-methylphenol with diethylenetriamine or 1,2-bis(3-amino propylamino)ethane produce the 12-membered N{sub 3}O and 17-membered N{sub 4}O macrocyclic complexes, respectively. The geometry of the complexes has been determined with the help of electronic and EPR spectroscopic values and found to be five coordinated square pyramidal and, six coordinated distorted tetragonal for 12-membered and 17-membered macrocyclic complexes, respectively. Electrochemical studies of the mononuclear N{sub 3}O and N{sub 4}O copper(II) complexes show one irreversible one electron reduction wave at E{sup pc} = .1.35 and .1.15 V respectively, and the corresponding nickel(II) complexes show irreversible one-electron reduction wave at E{sup pc} = .1.25 and .1.22 V, respectively. The nickel(II) complexes show irreversible one-electron oxidation wave at Epa = +0.84 and +0.82 V, respectively. All the complexes were evaluated for in vitro antimicrobial activity against the human pathogenic bacteria and fungi.

High-Temperature Wide Thermal Hysteresis of an Iron(II Dinuclear Double Helicate

Directory of Open Access Journals (Sweden)

Shiori Hora

2017-07-01

Full Text Available Two new dinuclear iron(II complexes (1·PF6 and 1·AsF6 of the general formula [FeII2(L2C32](X4·nH2O·mMeCN (X = PF6, n = m = 1.5 for 1·PF6 and X = AsF6, n = 3, m = 1 for 1·AsF6 have been prepared and structurally characterized, where L2C3 is a bis-1,2,3-triazolimine type Schiff-base ligand, 1,1′-[propane-1,3-diylbis(1H-1,2,3-triazole-1,4-diyl]bis{N-[2-(pyridin-2-ylethyl]methanimine}. Single crystal X-ray structure analyses revealed that 1·PF6 and 1·AsF6 are isostructural. The complex-cation [FeII2(L2C32]4+ of both has the same dinuclear double helicate architecture, in which each iron(II center has an N6 octahedral coordination environment. Neighboring helicates are connected by intermolecular π–π interactions to give a chiral one-dimensional (1D structure, and cationic 1D chains with the opposite chirality exist in the crystal lattice to give a heterochiral crystal. Magnetic and differential scanning calorimetry (DSC studies were performed only for 1·AsF6, since the thermal stability in a high-temperature spin crossover (SCO region of 1·PF6 is poorer than that of 1·AsF6. 1·AsF6 shows an unsymmetrical hysteretic SCO between the low-spin–low-spin (LS–LS and high-spin–high-spin (HS–HS states at above room temperature. The critical temperatures of warming (Tc↑ and cooling (Tc↓ modes in the abrupt spin transition area are 485 and 401 K, respectively, indicating the occurrence of 84 K-wide thermal hysteresis in the first thermal cycle.

Bonding coordination requirements induce antiferromagnetic coupling between m-phenylene bridged o-iminosemiquinonato diradicals.

Science.gov (United States)

Dei, Andrea; Gatteschi, Dante; Sangregorio, Claudio; Sorace, Lorenzo; Vaz, Maria G F

2003-03-10

Triply bridged bis-iminodioxolene dinuclear metal complexes of general formula M(2)(diox-diox)(3), with M = Co, Fe, have been synthesized using the bis-bidentate ligand N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,3-phenylenediamine. These complexes were characterized by means of X-ray, HF-EPR, and magnetic measurements. X-ray structures clearly show that both complexes can be described as containing three bis-iminosemiquinonato ligands acting in a bis-bidentate manner toward tripositive metal ions. The magnetic data show that both of these complexes have singlet ground states. The observed experimental behavior indicates the existence of intraligand antiferromagnetic interactions between the three pairs of m-phenylene units linked iminosemiquinonato radicals (J = 21 cm(-)(1) for the cobalt complex and J = 11 cm(-)(1) for the iron one). It is here suggested that the conditions for the ferromagnetic coupling that is expected to characterize the free diradical ligand are no longer satisfied because of the severe torsional distortion induced by the metal coordination.

Syntheses, molecular and crystalline architectures, and ...

Indian Academy of Sciences (India)

Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a pentadentate N-donor Schiff base. SUBHASIS ROYa, SOMNATH CHOUBEYa, SUMITAVA KHANa, KISHALAY BHARa,. PARTHA MITRAb and BARINDRA ...

Green and selective synthesis of N-substituted amides using water soluble porphyrazinato copper(II) catalyst

International Nuclear Information System (INIS)

Ghodsinia, Sara S.E.; Akhlaghinia, Batool; Eshghi, Hossein; Safaei, Elham

2013-01-01

N, N',N , N ' -Tetramethyl tetra-2,3-pyridinoporphyrazinato copper(II) methyl sulfate ([Cu(2,3-tmtppa)](MeSO 4 ) 4 ) efficiently catalyzed the direct conversion of nitriles to N-substituted amides. The one pot selective synthesis of the N-substituted amides from nitriles and primary amines was performed in refluxing H 2 O. The catalyst was recovered and reused at least four times, maintaining its efficiency. (author)

Design, synthesis and physico-chemical investigation of a dinuclear ...

Indian Academy of Sciences (India)

Unknown

Department of Chemistry, Karnatak University, Dharwad 580 003, India e-mail: ... bridge 1. Zinc-containing, carboxylate-bridged bimetallic centres are widespread .... The free ligand shows an enhanced fluorescent intensity on complexation.

Deprotonation induced ligand-to-metal electron transfer: Synthesis of a mixed-valence Rh(-I,I) dinuclear compound and its reaction with dioxygen

NARCIS (Netherlands)

Tejel, C.; Ciriano, M.A.; del Río, M.P.; van den Bruele, F.J.; Hetterscheid, D.G.H.; Tsichlis i Spithas, N.; de Bruin, B.

2008-01-01

Treatment of bis(2-picolyl)amine (bpa) with [{Rh(nbd)(mu-OMe))(2)] leads to unexpected and unique redox asymmetric dinuclear Rh-I, Rh+I complex [{Rh(ndb)}(2)(bpa-2H)] (2) with a pi-coordinating imine bound to a tetrahedral low valent rhodate(-I). Mono-oxygenation of the deprotonated bpa ligand in 2

trans-Bis(perchlorato-κOtetrakis(1H-pyrazole-κN2copper(II

Directory of Open Access Journals (Sweden)

Viktor Zapol'skii

2008-10-01

Full Text Available The title compound, [Cu(ClO42(C3H4N24], was obtained unexpectedly by the reaction of copper(II perchlorate hexahydrate with equimolar amounts of 1-chloro-1-nitro-2,2,2-tripyrazolylethane in methanol solution. The crystal structure comprises octahedrally coordinated Cu2+ ions, located on an inversion centre, with four pyrazole ligands in the equatorial plane. The average Cu—N distance is 2.000 (1 Å. Two perchlorate ions are coordinated to copper in trans positions [Cu—O = 2.4163 (11 Å].

Green and selective synthesis of N-substituted amides using water soluble porphyrazinato copper(II) catalyst

Energy Technology Data Exchange (ETDEWEB)

Ghodsinia, Sara S.E.; Akhlaghinia, Batool; Eshghi, Hossein, E-mail: akhlaghinia@um.ac.ir [Ferdowsi University of Mashhad (Iran, Islamic Republic of). Faculty of Sciences. Department of Chemistry; Safaei, Elham [Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan (Iran, Islamic Republic of). Department of Chemistry

2013-06-15

N, N',N{sup ,} N{sup '}-Tetramethyl tetra-2,3-pyridinoporphyrazinato copper(II) methyl sulfate ([Cu(2,3-tmtppa)](MeSO{sub 4}){sub 4}) efficiently catalyzed the direct conversion of nitriles to N-substituted amides. The one pot selective synthesis of the N-substituted amides from nitriles and primary amines was performed in refluxing H{sub 2}O. The catalyst was recovered and reused at least four times, maintaining its efficiency. (author)

Magnetic, catalytic, EPR and electrochemical studies on binuclear ...

Indian Academy of Sciences (India)

Unknown

binuclear copper(II) complexes derived from 3,4-disubstituted phenol ... M. Avanta G.B.C., Australia atomic absorption spectrophotometer. .... hydroxide. ... in OH bridged complexes may give rise to poor ligand–metal orbital overlap. The.

Thermoelectrical and thermal analyses of copper(II) acetate monohydrate ZnO-matrix composite powder obtained by freeze-drying

International Nuclear Information System (INIS)

Bellini, Jusmar Valentin; Pineda, Edgardo Alfonso Gomez; Rocha, Raquel de Almeida; Ponzoni, Andre Luis de Lima; Paesano, Andrea

2006-01-01

The thermal history of freeze-dried mixtures of composite powders containing ZnO-matrix and (CH 3 COO) 2 Cu.H 2 O (copper(II) acetate monohydrate) was undertaken by thermal analysis (TA) coupled to thermoelectrical analysis (TEA). Experiments were carried out on compacted samples, under non-isothermal conditions, in air, up to 350 deg. C, by measuring the electrical resistance during heating, called thermoelectrical resistometry (TER), and by differential scanning calorimetry (DSC). Activation energy (E a ) for exothermal events related to the decomposition of (CH 3 COO) 2 Cu (copper(II) acetate, CuAc 2 ), observed within the range 225-325 deg. C, was estimated according to ASTM E 698 method. Values of E a equal to 154 and 155 kJ/mol were obtained by TER and DSC, respectively. TER showed that the thermal decomposition of CuAc 2 involves the liberation of electrons. Results also indicated that TER may be used as an alternative or complementary method for the study of the thermal decomposition mechanisms of transition metal(II) acetates

Complejos de halógeno acetatos de uranio (IV y torio (IV con sulfoxidos y fosfinoxidos

Directory of Open Access Journals (Sweden)

Omar Velasquez

2010-09-01

Full Text Available En este trabajo se ha Investigado el efecto sterico sobre los modos de coordinación del grupo carboxilato (unidentado, bidentado y puente, en complejos de halógeno acetato con fosfinóxidos y sulfóxidos y la correlación de los resultadoscon el modelo "Cone Angle" e\\ cual ha sido descrito en otra publicación previa' Los complejos preparados son: M(RCO ^ .nL donde n = 4, M = Th ó U, L = Me^SO (dmso, R = CF,3 y L = Me3P0 (tmpo; n = 3, M = Th, L = tmpo, R = CF3 y L = ppo o dmso, R OCCI3; M = U, L = t p p o , R =CF3 y L =dmso, dpso, R = C C l 3 ; n = 2 , M = T h , L = tppo, R = CF3, CHCI^On^ 1, M = Th ó U, L =dmso.

The role of the dinuclear system in the processes of nuclear fusion, quasi-fission, fission and cluster formation

International Nuclear Information System (INIS)

Volkov, V.V.

1999-01-01

The nuclear fusion, quasi-fission, fission and cluster formation in an excited nucleus are considered as the processes of the formation and evolution of the dinuclear system. This approach allows one to reveal new aspects of nuclear fusion, to show that quasi-fission plays an important role in nuclear reactions used to synthesise superheavy elements. A qualitative picture is given of the fission process of an excited nucleus and an important role of cluster formation in this process is shown

Iodometric determination of peroxydiphosphate in the presence of copper(II) or iron(II) as catalyst.

Science.gov (United States)

Kapoor, S; Sharma, P D; Gupta, Y K

1975-09-01

Peroxydiphosphate can be determined iodometrically in the presence of a large excess of potassium iodide with copper(II) or iron(II) as catalyst through the operation of the Cu(II)/Cu(I) or Fe(II)/Fe(III) cycle. The method is applicable in HClO(4), H(2)SO(4), HCl and CH(3)COOH acid media in the range 0.1-1.0M studied. Nickel, manganese(II), cobalt(II), silver, chloride and phosphate are without effect.

Evaluación de diferentes concentraciones de etanol rectificado en la producción del “bioaroma” acetato de etilo y proteína unicelular por Candida utilis var. major C.E.C.T. 1430

Directory of Open Access Journals (Sweden)

Carlos León Torres

2010-01-01

Full Text Available El trabajo tuvo como objetivo evaluar diferentes concentraciones de etanol rectificado en la producción del “bioaroma” acetato de etilo y proteína unicelular por Candida utilis var.major . Se construyó un biorreactor de 16 cm de altura tipo tanque agitado con turbina Rushton. La preparación del inóculo fue realizada a partir de la cepa Candida utilis var.major C.E.C.T. 1430. El medio de cultivo fue formulado a partir de diluciones de etanol rectificado desde 10 hasta 35 g /L en intervalos de cada 5 unidades. El bioproceso se llevó a cabo a 25 ºC, pH de 4.5 – 5.5 y durante 60 horas. Se encontró que la biomasa y la productividad aumentan progresivamente, de 4.82 a 7.90 g/L y de 0.082 a 0.108 g/L - h respectivamente. Así mismo se determinó que a medida que aumenta la concentración (g/L de etanol rectificado, la producción y la productividad disminuyen. El rendimiento de acetato de etilo, fue máximo a la concentración de 15 g/L de etanol rectificado (5.7% y mínimo a 35 g/L y ( 1.97% respectivamente. Se concluye que el incremento de la concentración de etanol rectificado no influye aumentando la producción y rendimiento del “bioaroma” acetato de etilo y de la proteína unicelular de Candida utilis var. major .

Synthesis and SMM behaviour of trinuclear versus dinuclear 3d-5f uranyl(v)-cobalt(ii) cation-cation complexes.

Science.gov (United States)

Chatelain, Lucile; Tuna, Floriana; Pécaut, Jacques; Mazzanti, Marinella

2017-05-02

Trinuclear versus dinuclear heterodimetallic U V O 2 + Co 2+ complexes were selectively assembled via a cation-cation interaction by tuning the ligand. The trimeric complex 2, with a linear [Co-O[double bond, length as m-dash]U[double bond, length as m-dash]O-Co] core, exhibits magnetic exchange and slow relaxation with a reversal barrier of 30.5 ± 0.9 K providing the first example of a U-Co exchange-coupled SMM.

Preparation and testing of a tetra-amine copper(II) chitosan bead system for enhanced phosphate remediation.

Science.gov (United States)

Kumar, Ilango Aswin; Viswanathan, Natrayasamy

2018-03-01

A tetra-amine copper(II) chitosan bead system (TAC@CS composite beads) was developed by grafting tetra-amine copper(II) (TAC) with chitosan (CS) and utilized for phosphate removal. The prepared TAC@CS composite beads possess enhanced phosphate sorption capacity (SC) of 41.42 ± 0.071 mg/g than copper grafted chitosan (Cu@CS) composite, TAC and chitosan which were found to be 37.01 ± 0.803, 33.20 ± 0.650 and 7.24 ± 0.059 mg/g respectively. In batch mode, various adsorption influencing parameters like contact time, initial phosphate concentration, solution pH, co-anions and temperature were optimized for maximum phosphate sorption. The prepared adsorbents were characterized by FTIR, XRD, UV-Visible, SEM and EDAX analysis. The adsorption isotherms and thermodynamic parameters of the adsorbent were studied. The feasible phosphate uptake mechanism of TAC@CS biocomposite beads was reported. The reusability studies of TAC@CS composite beads were carried out using NaOH as elutant. The suitability of TAC@CS composite beads at field conditions was tested with phosphate contaminated field water samples collected from nearby areas of Dindigul district. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis, spectroscopy, magnetic and redox behaviors of copper(II) complexes with tert-butylated salen type ligands bearing bis(4-aminophenyl)ethane and bis(4-aminophenyl)amide backbones.

Science.gov (United States)

Kasumov, Veli T; Yerli, Yusuf; Kutluay, Aysegul; Aslanoglu, Mehmet

2013-03-01

New salen type ligands, N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-ethylenedianiline [(X=H (1), 5-tert-butyl (2)] and N,N'-bis(X-3-tert-butylsalicylidene)-4,4'-amidedianiline [X=H (3), 5-tert (4)] and their copper(II) complexes 5-8, have been synthesized. Their spectroscopic (IR, (1)H NMR, UV/vis, ESR) properties, as well as magnetic and redox-reactivity behavior are reported. IR spectra of 7 and 8 indicate the coordination of amide oxygen atoms of 3 and 4 ligands to Cu(II). The solid state ESR spectra of 5-8 exhibits less informative exchange narrowed isotropic or anisotropic signals with weak unresolved low field patterns. The magnetic moments of 5 (2.92 μ(B) per Cu(II)) and 6 (2.79 μ(B) per Cu(II)) are unusual for copper(II) complexes and considerably higher than those for complexes 7 and 8. Cryogenic measurements (300-10 K) show weak antiferromagnetic exchange interactions between the copper(II) centers in complexes 6 and 8. The results of electrochemical and chemical redox-reactivity studies are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

Fluorescence-based detection of nitric oxide in aqueous and methanol media using a copper(II) complex.

Science.gov (United States)

Mondal, Biplab; Kumar, Pankaj; Ghosh, Pokhraj; Kalita, Apurba

2011-03-14

The quenched fluorescent intensity of a copper(II) complex, 1, of a fluorescent ligand, in degassed methanol or aqueous (buffered at pH 7.2) solution, was found to reappear on exposure to nitric oxide. Thus, it can function as a fluorescence based nitric oxide sensor. It has been found that the present complex can be used to sense nanomolar quantities of nitric oxide in both methanol and pH 7.2 buffered-water medium.

Modulating p-hydroxycinnamate behavior as a ditopic linker or photoacid in copper(ii) complexes with an auxiliary pyridine ligand.

Science.gov (United States)

Soldevila-Sanmartín, Joan; Calvet, Teresa; Font-Bardia, Merce; Domingo, Concepción; Ayllón, José A; Pons, Josefina

2018-05-08

The reaction of copper(ii) acetate monohydrate with p-hydroxycinnamic acid (HpOHcinn) and different pyridine derivatives (4-tert-butylpyridine, 4-tBupy; 4-acetylpyridine, 4-Acpy; 3-phenylpyridine, 3-Phpy; 4-phenylpyridine, 4-Phpy) was essayed in methanol solvent at room temperature. The crystal structures of the resulting compounds were elucidated. Their analysis shows that the choice of pyridine ligands determines different coordination modes of the pOHcinn ligand and the Cu(ii) coordination, nuclearity and geometry. The pOHcinn acts as a monodentate carboxylate ligand in combination with 4-tBupy or 4-Phpy, yielding monomers and dimers, associated by hydrogen bonds into supramolecular networks in which the phenol group plays a key role. Conversely, in combination with 4-Acpy or 3-Phpy, the phenol group coordinates directly to the Cu(ii), acting as a ditopic ligand and yielding 2D coordination polymers. The compound containing 3-Phpy shows interesting MeOH-H2O reversible exchange behavior. Not only has the pyridine auxiliary ligand had a tremendous effect on the coordination mode of pOHcinn, but also its reactivity is influenced. Particularly, in the case of the compound containing 4-Phpy, it undergoes a photoinduced process, in which the phenol group deprotonates and coordinates to Cu(ii) as a phenoxy ligand. This yields a coordination polymer in which two different dimers alternate, bridged by the resulting pOcinn ligand. The magneto-structural correlation of this compound is also discussed.

New μ-OAC bridged dinuclear copper(II) complex with tridentate Schiff base ligand: synthesis, characterization, crystal structure, and CuO nano-particles formation

Czech Academy of Sciences Publication Activity Database

Grivani, G.; Eigner, Václav; Dušek, Michal; Sadeghi, B.; Khalaji, A.D.

2015-01-01

Roč. 41, č. 7 (2015), s. 456-461 ISSN 1070-3284 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : Schiff base * complex structure * x-ray crystallography * Jana2006 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.516, year: 2015

Scalable room-temperature conversion of copper(II) hydroxide into HKUST-1 (Cu3 (btc)2).

Science.gov (United States)

Majano, Gerardo; Pérez-Ramírez, Javier

2013-02-20

Copper(II) hydroxide is converted directly to HKUST-1 (Cu(3) (btc)(2) ) after only 5 min at room-temperature in aqueous ethanolic solution without the need of additional solvents. Scale up to the kilogram scale does not influence porous properties yielding pure-phase product with a remarkable total surface area exceeding 1700 m(2) g(-1) featuring aggregates of nanometer-sized crystals (<600 nm) and extremely high space-time yields. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two Zn coordination polymers with meso-helical chains based on mononuclear or dinuclear cluster units

Energy Technology Data Exchange (ETDEWEB)

Qin, Ling, E-mail: qinling@hfut.edu.cn [Department of Chemical Engineering and Food Processing, Xuancheng Campus, Hefei University of Technology, Xuancheng 242000, Anhui (China); Jiangsu Engineering Technology Research Center of Environmental Cleaning Materials (CEM), School of Environmental Sciences and Engineering, Nanjing University of Information Science and Technology (China); State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093 (China); Qiao, Wen-Cheng; Zuo, Wei-Juan; Zeng, Si-Ying; Mei, Cao; Liu, Chang-Jiang [Department of Chemical Engineering and Food Processing, Xuancheng Campus, Hefei University of Technology, Xuancheng 242000, Anhui (China)

2016-07-15

Two zinc coordination polymers {[Zn_2(TPPBDA)(oba)_2]·DMF·1.5H_2O}{sub n} (1), {[Zn(TPPBDA)_1_/_2(tpdc)]·DMF}{sub n} (2) have been synthesized by zinc metal salt, nanosized tetradentate pyridine ligand with flexible or rigid V-shaped carboxylate co-ligands. These complexes were characterized by elemental analyses and X-ray single-crystal diffraction analyses. Compound 1 is a 2-fold interpenetrated 3D framework with [Zn{sub 2}(CO{sub 2}){sub 4}] clusters. Compound 2 can be defined as a five folded interpenetrating bbf topology with mononuclear Zn{sup 2+}. These mononuclear or dinuclear cluster units are linked by mix-ligands, resulting in various degrees of interpenetration. In addition, the photoluminescent properties for TPPBDA ligand under different state and coordination polymers have been investigated in detail. - Graphical abstract: Two zinc coordination polymers have been synthesized by zinc metal salt, nanosized tetradentate pyridine ligand with flexible or rigid V-shaped carboxylate co-ligands. Compound 1 is a 2-fold interpenetrated 3D framework with [Zn{sub 2}(CO{sub 2}){sub 4}] clusters. Compound 2 can be defined as a five folded interpenetrating bbf topology with mononuclear Zn{sup 2+}. In addition, the photoluminescent properties for TPPBDA ligand under different status and coordination polymers have been investigated in detail. Display Omitted - Highlights: • Two Zn coordination polymers based on mononuclear or dinuclear cluster units have been synthesized. • Compound 1 is a 2-fold interpenetrated 3D framework with [Zn{sub 2}(CO{sub 2}){sub 4}] clusters. • Compound 2 is a five folded interpenetrating bbf topology with mononuclear Zn{sup 2+}. • The photoluminescent properties for TPPBDA with different state and two coordination polymers have been investigated.

μ-Oxalato-bis[bis(triphenylphosphinecopper(I] dichloromethane disolvateATR dedicates this paper to the honor of Professor S. Peter Tanner for rekindling a love of inorganic chemistry.

Directory of Open Access Journals (Sweden)

Andrew D. Royappa

2013-02-01

Full Text Available The dinuclear molecule of the title compound, [Cu2(C2O4(C18H15P4]·2CH2Cl2, lies across an inversion center with a strictly planar bridging oxalate ligand coordinating two CuI ions via two pairs of O atoms. Two triphenylphosphine ligands also coordinate each symmetry-related CuI ion, resulting in a distorted tetrahedral geometry [O—Cu—O = 80.57 (5° and P—Cu—P = 125.72 (2°]. In the crystal, there are two dichloromethane solvent molecules for each dinuclear complex.

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences. Kishalay Bhar. Articles written in Journal of Chemical Sciences. Volume 125 Issue 4 July 2013 pp 715-721. Syntheses, molecular and crystalline architectures, and luminescence behaviour of terephthalate bridged heptacoordinated dinuclear lead(II) complexes containing a ...

Systematic Introduction of Aromatic Rings to Diphosphine Ligands for Emission Color Tuning of Dinuclear Copper(I) Iodide Complexes.

Science.gov (United States)

Okano, Yuka; Ohara, Hiroki; Kobayashi, Atsushi; Yoshida, Masaki; Kato, Masako

2016-06-06

We have newly synthesized two solution-stable luminescent dinuclear copper(I) complexes, [Cu2(μ-I)2(dpppy)2] (Cu-py) and [Cu2(μ-I)2(dpppyz)2] (Cu-pyz), where dpppy = 2,3-bis(diphenylphosphino)pyridine and dpppyz = 2,3-bis(diphenylphosphino)pyrazine, using chelating diphosphine ligands composed of N-heteroaromatic rings. X-ray analysis clearly indicates that the molecular structures of Cu-py and Cu-pyz are almost identical with that of the parent complex, [Cu2(μ-I)2(dppb)2] [Cu-bz; dppb = 2,3-bis(diphenylphosphino)benzene]. Complexes Cu-py and Cu-pyz exhibit luminescence [emission quantum yield (Φem) = 0.48 and 0.02, respectively] in the solid state at 298 K. A wide emission color tuning, from 497 to 638 nm (energy = 0.55 eV, with an emission color ranging from green to reddish-orange), was achieved in the solid state by the introduction of pyridinic N atoms into the bridging phenyl group between the two diphenylphosphine groups. Density functional theory calculations suggest that the emission could originate from the effective combination of the metal-to-ligand charge-transfer excited state with the halide-to-ligand charge-transfer excited state. Thus, the emission color change is due to stabilization of the π* levels of the central aryl group in the diphosphine ligand. Furthermore, these copper(I) complexes exhibit thermally activated delayed fluorescence at 298 K because of the small singlet-triplet energy difference (ΔE = 523 and 564 cm(-1) for Cu-py and Cu-pyz, respectively). The stability of these complexes in chloroform, due to the rigid bonds between the diphosphine ligands and the Cu(I) ions, enables the preparation of emissive poly(methyl methacrylate) films by the solution-doping technique.

Electrical conductivity of solutions of copper(II) nitrate crystalohydrate in dimethyl sulfoxide

Science.gov (United States)

Mamyrbekova, Aigul K.; Mamitova, A. D.; Mamyrbekova, Aizhan K.

2016-06-01

Conductometry is used to investigate the electric conductivity of Cu(NO3)2 ṡ 3H2O solutions in dimethyl sulfoxide in the 0.01-2.82 M range of concentrations and at temperatures of 288-318 K. The limiting molar conductivity of the electrolyte and the mobility of Cu2+ and NO 3 - ions, the effective coefficients of diffusion of copper(II) ions and nitrate ions, and the degree and constant of electrolytic dissociation are calculated for different temperatures from the experimental results. It is established that solutions containing 0.1-0.6 M copper nitrate trihydrate in DMSO having low viscosity and high electrical conductivity can be used in electrochemical deposition.

Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study.

Science.gov (United States)

Hricovíni, Michal; Mazúr, Milan; Sîrbu, Angela; Palamarciuc, Oleg; Arion, Vladimir B; Brezová, Vlasta

2018-03-21

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.

Copper(II) Complexes of Phenanthroline and Histidine Containing Ligands: Synthesis, Characterization and Evaluation of their DNA Cleavage and Cytotoxic Activity.

Science.gov (United States)

Leite, Sílvia M G; Lima, Luís M P; Gama, Sofia; Mendes, Filipa; Orio, Maylis; Bento, Isabel; Paulo, António; Delgado, Rita; Iranzo, Olga

2016-11-21

Copper(II) complexes have been intensely investigated in a variety of diseases and pathological conditions due to their therapeutic potential. The development of these complexes requires a good knowledge of metal coordination chemistry and ligand design to control species distribution in solution and tailor the copper(II) centers in the right environment for the desired biological activity. Herein we present the synthesis and characterization of two ligands HL1 and H 2 L2 containing a phenanthroline unit (phen) attached to the amino group of histidine (His). Their copper(II) coordination properties were studied using potentiometry, spectroscopy techniques (UV-vis and EPR), mass spectrometry (ESI-MS) and DFT calculations. The data showed the formation of single copper complexes, [CuL1] + and [CuL2], with high stability within a large pH range (from 3.0 to 9.0 for [CuL1] + and from 4.5 to 10.0 for [CuL2]). In both complexes the Cu 2+ ion is bound to the phen unit, the imidazole ring and the deprotonated amide group, and displays a distorted square pyramidal geometry as confirmed by single crystal X-ray crystallography. Interestingly, despite having similar structures, these copper complexes show different redox potentials, DNA cleavage properties and cytotoxic activity against different cancer cell lines (human ovarian (A2780), its cisplatin-resistant variant (A2780cisR) and human breast (MCF7) cancer cell lines). The [CuL2] complex has lower reduction potential (E pc = -0.722 V vs -0.452 V for [CuL1] + ) but higher biological activity. These results highlight the effect of different pendant functional groups (carboxylate vs amide), placed out of the coordination sphere, in the properties of these copper complexes.

Coumarin-Based Fluorescent Probes for Dual Recognition of Copper(II and Iron(III Ions and Their Application in Bio-Imaging

Directory of Open Access Journals (Sweden)

Olimpo García-Beltrán

2014-01-01

Full Text Available Two new coumarin-based “turn-off” fluorescent probes, (E-3-((3,4-dihydroxybenzylideneamino-7-hydroxy-2H-chromen-2-one (BS1 and (E-3-((2,4-dihydroxybenzylideneamino-7-hydroxy-2H-chromen-2-one (BS2, were synthesized and their detection of copper(II and iron(III ions was studied. Results show that both compounds are highly selective for Cu2+ and Fe3+ ions over other metal ions. However, BS2 is detected directly, while detection of BS1 involves a hydrolysis reaction to regenerate 3-amino-7-hydroxycoumarin (3 and 3,4-dihydroxybenzaldehyde, of which 3 is able to react with copper(II or iron(III ions. The interaction between the tested compounds and copper or iron ions is associated with a large fluorescence decrease, showing detection limits of ca. 10−5 M. Preliminary studies employing epifluorescence microscopy demonstrate that Cu2+ and Fe3+ ions can be imaged in human neuroblastoma SH-SY5Y cells treated with the tested probes.

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Indian Academy of Sciences (India)

Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India e-mail: lahiri@chem.iitb.ac.in. Abstract. Electronic structural forms of selected mononuclear and dinuclear ruthenium complexes encom- passing redox non-innocent terminal as well as bridging ligands have been addressed.

1D polymeric copper(I) and dinuclear silver(I) complexes of a bidentate Schiff base ligand: synthesis, spectroscopic characterization and thermal studies

Czech Academy of Sciences Publication Activity Database

Khalaji, A.D.; Peyghoun, S.J.; Akbari, A.; Feizi, N.; Dušek, Michal; Eigner, Václav

2016-01-01

Roč. 119, Sep (2016), s. 429-433 ISSN 0277-5387 R&D Projects: GA ČR GA15-12653S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : one-dimensional polymer * copper(I) * di-nuclear complex * silver(I) * crystal structure analysis Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.926, year: 2016

Crystal structure of bis[μ-methoxy(pyridin-2-ylmethanolato-κ3N,O:O]bis[chloridocopper(II

Directory of Open Access Journals (Sweden)

Sujirat Boonlue

2015-02-01

Full Text Available The racemic title compound, [Cu2(C7H8NO22Cl2], is composed of dinuclear molecules in which methoxy(pyridin-2-ylmethanolate ligands bridge two symmetry-related CuII ions. Each CuII ion is coordinated in a square-planar geometry by one Cl atom, the N and O atoms of the bidentate ligand and the bridging O atom of the centrosymmetrically related bidentate ligand. The separation between the two CuII atoms is 3.005 (1 Å. In the crystal, non-classical C—H...O hydrogen bonds, weak π–π stacking [centroid–centroid distance = 4.073 (1 Å] and weak electrostatic Cu...Cl interactions [3.023 (1 Å] link the dinuclear molecules into chains running parallel to the b axis. These chains are further connected by weak C—H...Cl hydrogen bonds directed approximately along the a axis, forming a three-dimensional supramolecular network.

Copper(II) and molybdenum(VI) complexes of a tridentate ONN donor isothiosemicarbazone: synthesis, characterization, X-ray, TGA and DFT

Czech Academy of Sciences Publication Activity Database

Fasihizad, A.; Akbari, A.; Ahmadi, M.; Dušek, Michal; Henriques, Margarida Isabel Sousa; Pojarová, Michaela

2016-01-01

Roč. 115, Sep (2016), s. 297-305 ISSN 0277-5387 R&D Projects: GA ČR(CZ) GA14-03276S; GA MŠk LO1603 EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : isothiosemicarbazone * Copper(II) complex * molybdenum(VI) complex * crystal structure * DFT Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.926, year: 2016

47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section 80.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Bridge-to-Bridge Act § 80.1007 Bridge-to-bridge radiotelephone installation. Use of the bridge-to-bridge...

μ-4,4′-Bipyridine-κ2N:N′-bis[aqua(4,4′-bipyridine-κN(l-valinato-κ2N,Ocopper(II] dinitrate dihydrate

Directory of Open Access Journals (Sweden)

Mao-Chun Hong

2008-02-01

Full Text Available In the title dinuclear complex, [Cu2(C5H10NO22(C10H8N23(H2O2](NO32·2H2O, each of the two l-valinate anions chelates a CuII center through the amino N and carboxylate O atom, forming a five-membered ring. A 4,4′-bipyridine molecule bridges two water-coordinated Cu atoms, each of which is connected to another 4,4′-bipyridine, giving rise to a square-pyramidal coordination geometry for the CuII centers. The dinuclear dications, nitrate anions and uncoordinated water molecules are linked into a two-dimensional structure.

Catalytic bleaching of cotton: molecular and macroscopic aspects

NARCIS (Netherlands)

Topalovic, T.

2007-01-01

The scope of this thesis was to investigate the possibility of low-temperature cotton bleaching employing dinuclear tri- -oxo bridged manganese(IV) complex of the ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (MnTACN) as the catalyst in the system with hydrogen peroxide. With this objective in

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Dicopper(II/II) complex displays weak - transition bands in the visible region, while dicopper(I/I) complex displays strong MLCT band in the same region. Both the dinuclear complexes are of non-intimate nature and show interesting solution electrochemical behaviour. EPR spectral study of -bis(imidazolidino) bridged ...

Non-covalent interactions in 2-methylimidazolium copper(II) complex (MeImH)2[Cu(pfbz)4]: Synthesis, characterization, single crystal X-ray structure and packing analysis

Science.gov (United States)

Sharma, Raj Pal; Saini, Anju; Kumar, Santosh; Kumar, Jitendra; Sathishkumar, Ranganathan; Venugopalan, Paloth

2017-01-01

A new anionic copper(II) complex, (MeImH)2 [Cu(pfbz)4] (1) where, MeImH = 2-methylimidazolium and pfbz = pentafluorobenzoate has been isolated by reacting copper(II) sulfate pentahydrate, pentafluorobenzoic acid and 2-methylimidazole in ethanol: water mixture in 1:2:2 molar ratio. This complex 1 has been characterized by elemental analysis, thermogravimetric analysis, spectroscopic techniques (UV-Vis, FT-IR) and conductance measurements. The complex salt crystallizes in monoclinic crystal system with space group C2/c. Single crystal X-ray structure determination revealed the presence of discrete ions: [Cu(pfbz)4]2- anion and two 2-methylimidazolium cation (C4H7N2)+. The crystal lattice is stabilized by strong hydrogen bonding and F⋯F interactions between cationic-anionic and the anionic-anionic moieties respectively, besides π-π interactions.

A comparison of DNA binding profiles of dinuclear platinum compounds with polyamine linkers and the trinuclear platinum phase II clinical agent BBR3464

Czech Academy of Sciences Publication Activity Database

McGregor, T. D.; Hegmans, A.; Kašpárková, Jana; Neplechová, Kamila; Nováková, Olga; Peňázová, Hana; Vrána, Oldřich; Brabec, Viktor; Farrel, N.

2002-01-01

Roč. 7, 4/5 (2002), s. 397-404 ISSN 0949-8257 R&D Projects: GA ČR GA305/99/0695; GA ČR GA301/00/0556; GA ČR GA301/98/P231; GA AV ČR IAA5004101; GA AV ČR IAA7004805 Institutional research plan: CEZ:AV0Z5004920 Keywords : unwinding * dinuclear platinum * hydrogen bonding Subject RIV: BO - Biophysics Impact factor: 3.911, year: 2002

Synthesis, characterisation and modelling of a ferromagnetically coupled chromium(III) Dimer

DEFF Research Database (Denmark)

Morsing, Thorbjørn Juul; Weihe, Høgni; Bendix, Jesper

2014-01-01

A rare example of a ferromagnetically coupled dinuclear chromium(III) complex, the di-μ-hydroxobis[tetrakis(isothiocyanato)chromate(III)] anion, is reported. This complex has been synthesised from the oxo-bridged acetonitrile complex [(CH3CN)5CrOCr(NCCH3)5](BF4)4 and isolated as the solvated...

Fulltext PDF

Indian Academy of Sciences (India)

Administrator

Tridentate Schiff bases are excellent ligands in forming dinuclear complexes of metal ions which prefer square-planar geometry. Deprotonated monobasic arylhydrazones of 2- pyridine-carboxaldehyde can coordinate a metal ion via the pyridine-N, the imine-N and the amide-O atoms. We are interested in amide-O bridged ...

47 CFR 80.331 - Bridge-to-bridge communication procedure.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures § 80.331 Bridge-to-bridge communication procedure. (a) Vessels subject to the Bridge-to-Bridge Act transmitting on the designated navigational frequency must conduct...

Coordination of different ligands to copper(II) and cobalt(III) metal centers enhances Zika virus and dengue virus loads in both arthropod cells and human keratinocytes.

Science.gov (United States)

Dutta, Shovan; Celestine, Michael J; Khanal, Supreet; Huddleston, Alexis; Simms, Colin; Arca, Jessa Faye; Mitra, Amlan; Heller, Loree; Kraj, Piotr J; Ledizet, Michel; Anderson, John F; Neelakanta, Girish; Holder, Alvin A; Sultana, Hameeda

2018-01-01

Trace elements such as copper and cobalt have been associated with virus-host interactions. However, studies to show the effect of conjugation of copper(II) or cobalt(III) metal centers to thiosemicarbazone ligand(s) derived from either food additives or mosquito repellent such as 2-acetylethiazole or citral, respectively, on Zika virus (ZIKV) or dengue virus (serotype 2; DENV2) infections have not been explored. In this study, we show that four compounds comprising of thiosemicarbazone ligand derived from 2-acetylethiazole viz., (E)-N-ethyl-2-[1-(thiazol-2-yl)ethylidene]hydrazinecarbothioamide (acetylethTSC) (compound 1), a copper(II) complex with acetylethTSC as a ligand (compound 2), a thiosemicarbazone ligand-derived from citral (compound 3) and a cobalt(III) complex with a citral-thiosemicarbazone ligand (compound 4) increased DENV2 and ZIKV replication in both mosquito C6/36 cells and human keratinocytes (HaCaT cells). Treatment of both cell lines with compounds 2 or 4 showed increased dengue viral titers at all three tested doses. Enhanced dengue viral plaque formation was also noted at the tested dose of 100μM, suggesting higher production of infectious viral particles. Treatment with the compounds 2 or 4 enhanced ZIKV and DENV2 RNA levels in HeLa cell line and primary cultures of mouse bone marrow derived dendritic cells. Also, pre- or post treatments with conjugated compounds 2 or 4 showed higher loads of ZIKV or DENV2 envelope (E) protein in HaCaT cells. No changes in loads of E-protein were found in ZIKV-infected C6/36 cells, when compounds were treated after infection. In addition, we tested bis(1,10-phenanthroline)copper(II) chloride ([Cu(phen) 2 ]Cl 2 , (compound 5) and tris(1,10-phenanthroline)cobalt(III) chloride ([Co(phen) 3 ]Cl 3 , (compound 6) that also showed enhanced DENV2 loads. Also, we found that copper(II) chloride dehydrate (CuCl 2 ·2H 2 O) or cobalt(II) chloride hexahydrate (CoCl 2 ·6H 2 O) alone had no effects as "free" cations

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Each manganese(II) centre adopts a rare distorted trigonal prismatic geometry with an MnN4O2 chromophore.Chelation of the tetradentate Schiff base (L) along with bis(bidentate) bridging of two O atoms of tp complete hexacoordination around each manganese(II) centre. The dinuclear units of 1 are associated through ...

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

Complexes 1 and 2 react with dioxygen at ambient condition to form the corresponding hydroxo- or oxo-bridged dinuclear cobalt(III) or iron(III) complexes. On the other hand, the iron(III)-catecholate complex (3) activate dioxygen to undergo oxidative C-C bond cleavage of catechol. The selective formation of extradiol ...

MEDICIÓN DEL EQUILIBRIO LIQUIDO-VAPOR DEL SISTEMA METANOL-ACETATO DE METILO A 580 mmHg

Directory of Open Access Journals (Sweden)

Carlos Ariel Cardona

2008-03-01

Full Text Available En este trabajo se midió experimentalmente el equilibrio líquido-vapor para el sistema binario metanol–acetato de Metilo a 580 mmHg. Las mediciones experimentales fueron realizadas utilizando un equipo con recirculación tipo Cottrell. Los datos obtenidos fueron comparados con los resultados adquiridos de la simulación del equilibrio líquido-vapor del sistema bajo estudio. En la simulación se empleó el modelo de actividad NRTL para representar la no idealidad de la fase líquida (con parámetros encontrados en la literatura, y la ecuación de estado de Hayden O´Connel para la no idealidad de la fase vapor. De igual manera, se correlacionaron los datos para encontrar nuevos parámetros del modelo de actividad en NRTL. Además, a partir de datos experimentales medidos a 760 mmHg encontrados en la literatura para el sistema estudiado, se verificó la Ley de Vresky, la cual permite, sin necesidad de cálculos rigurosos, predecir la dirección de desplazamiento de un azeótropo binario cunado se varía la presión del sistema.

Tri-μ-oxido-bis[(5,10,15,20-tetraphenylporphyrinato-κ4Nniobium(V

Directory of Open Access Journals (Sweden)

Raoudha Soury

2011-07-01

Full Text Available In the title dinuclear NbV compound, [Nb2(C44H28N42O3], each Nb atom is seven-coordinated with three bridging O atoms and four N atoms from a chelating tetraphenylporphyrinate anion. The Nb—O bond lengths range from 1.757 (6 to 2.331 (6 Å, and the average (niobium–pyrrole N atom distance is 2.239 Å. In the dinuclear molecule, the Nb...Nb separation is 2.8200 (8 Å, and the dihedral angle between the two porphyrinate mean planes is 5.4 (1°. Weak intermolecular C—H...π interactions are present in the crystal structure.

Copper(II) complexes with aroylhydrazones

Indian Academy of Sciences (India)

Unknown

2JS1⋅S2⋅(S1 = S2 = 1/2) provided a value of –186(5) cm–1 for the coupling ..... Cu(pamh)Cl exists as polymeric chain species via equatorial-apical chloride bridges ..... Folgado J V, Henke W, Allman R, Stratemeier H, Beltran-Porter D, Rojo T ...

Kinetics of the oxidative hydroxylation of tetraphosphorus in the presence of copper(II) chloride modified by humic (fulvo-) acid

OpenAIRE

Zhaksyntay Kairbekov; Dina Akbayeva; Zh. Eshova

2012-01-01

It was established that in mild conditions (50-70 oC, РО2= 1 atm) white phosphorus effectively is oxidized by oxygen in water-toluene solutions of copper(II) chloride modified by humic (fulvo-) acid to give mainly phosphoric acid. Humic (fulvo-) acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, intermediate and final ...

Efeito da idade e da suplementação oral com o acetato de DL-alfa-tocoferol sobre os níveis séricos de vitamina E e sobre o metabolismo oxidativo dos neutrófilos em bezerros

Directory of Open Access Journals (Sweden)

J. N. Costa

2006-03-01

Full Text Available Este trabalho teve por objetivo avaliar o efeito da idade e da suplementação oral com acetato de DL-alfa-tocoferol sobre os níveis séricos de vitamina E e sobre o metabolismo oxidativo dos neutrófilos de bezerros da raça Jersey do nascimento aos 45 dias de idade. Foram utilizados 14 bezerros divididos em dois grupos de sete animais cada. O grupo tratamento recebeu 2g de acetato de DL-alfa-tocoferol, por via oral, diariamente, até os 45 dias de vida e o controle não recebeu nenhum tipo de suplementação para esta vitamina. Foram colhidas amostras de soro sanguíneo ao nascimento, aos cinco, 10, 20, 30 e 45 dias de idade, para: determinação sérica da vitamina E e para a avaliação da função dos neutrófilos. Concluímos que a suplementação oral com acetato de DL-alfa-tocoferol, na dose de 2 g/dia/VO, do nascimento aos 45 dias de idade aumentou significativamente (p≤ 0,05 os níveis séricos de vitamina E em bezerros. Os menores percentuais de neutrófilos redutores foram detectados logo após o nascimento e os maiores aos 45 dias de idade. A suplementação com vitamina E não alterou significativamente a função oxidativa dos neutrófilos, mas os valores superiores obtidos para os animais do grupo tratado, para o teste estimulado, sugerem uma ação neutrófilica mais potente diante uma infecção natural nesses animais.

Hydrolytic activity of μ-alkoxide/acetato-bridged binuclear Cu(II ...

Indian Academy of Sciences (India)

philic attack of the metal-bound hydroxide on the carboxyl of PNPP in the ... oping artificial enzymes with high efficiency under near neutral conditions is a big .... CH–OH); IR(KBr, film)νmax: 3394, 3055, 2896, 1633,. 1579, 1496, 1459, 1277, ...

Myocardial Bridge

Science.gov (United States)

... Center > Myocardial Bridge Menu Topics Topics FAQs Myocardial Bridge En español Your heart is made of muscle, ... surface of the heart. What is a myocardial bridge? A myocardial bridge is a band of heart ...

Electrochemical Water Oxidation and Stereoselective Oxygen Atom Transfer Mediated by a Copper Complex.

Science.gov (United States)

Kafentzi, Maria-Chrysanthi; Papadakis, Raffaello; Gennarini, Federica; Kochem, Amélie; Iranzo, Olga; Le Mest, Yves; Le Poul, Nicolas; Tron, Thierry; Faure, Bruno; Simaan, A Jalila; Réglier, Marius

2018-04-06

Water oxidation by copper-based complexes to form dioxygen has attracted attention in recent years, with the aim of developing efficient and cheap catalysts for chemical energy storage. In addition, high-valent metal-oxo species produced by the oxidation of metal complexes in the presence of water can be used to achieve substrate oxygenation with the use of H 2 O as an oxygen source. To date, this strategy has not been reported for copper complexes. Herein, a copper(II) complex, [(RPY2)Cu(OTf) 2 ] (RPY2=N-substituted bis[2-pyridyl(ethylamine)] ligands; R=indane; OTf=triflate), is used. This complex, which contains an oxidizable substrate moiety (indane), is used as a tool to monitor an intramolecular oxygen atom transfer reaction. Electrochemical properties were investigated and, upon electrolysis at 1.30 V versus a normal hydrogen electrode (NHE), both dioxygen production and oxygenation of the indane moiety were observed. The ligand was oxidized in a highly diastereoselective manner, which indicated that the observed reactivity was mediated by metal-centered reactive species. The pH dependence of the reactivity was monitored and correlated with speciation deduced from different techniques, ranging from potentiometric titrations to spectroscopic studies and DFT calculations. Water oxidation for dioxygen production occurs at neutral pH and is probably mediated by the oxidation of a mononuclear copper(II) precursor. It is achieved with a rather low overpotential (280 mV at pH 7), although with limited efficiency. On the other hand, oxygenation is maximum at pH 8-8.5 and is probably mediated by the electrochemical oxidation of an antiferromagnetically coupled dinuclear bis(μ-hydroxo) copper(II) precursor. This constitutes the first example of copper-centered oxidative water activation for a selective oxygenation reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coordination chemistry with phosphine and phosphine oxide-substituted hydroxyferrocenes.

Science.gov (United States)

Atkinson, Robert C J; Gibson, Vernon C; Long, Nicholas J; White, Andrew J P

2010-08-28

New unsymmetrical hydroxyferrocenes were synthesised from dibromoferrocene. The oxygen heteroatom was introduced via lithiation and quenching with bis-trimethylsilylperoxide followed by hydrolysis to unmask the hydroxyl functionality. The coordination chemistry of 1'-(diphenylphosphino)-1-hydroxyferrocene 2 was explored with palladium and rhodium precursors. A dinuclear palladium methyl complex with bridging ferrocenyloxo groups was obtained from the reaction between 2 and (cyclooctadiene)methylchloropalladium(II). With tetracarbonyldichlorodirhodium(I), two complexes were isolated. The major product was a bis ligand cis phosphine ligated complex with one ligand bound in a chelating mode and one with a pendant hydroxyl group. A minor product was crystallographically characterised as a dinuclear ferrocenyloxo-bridged rhodium carbonyl complex. The coordination chemistry of 2 and the corresponding phosphine oxide 3 was examined with group 4 metals and the resulting complexes examined as ethylene polymerisation catalysts. The ligands were found to bind in either a chelating fashion or with pendant phosphine donors. In all cases, low to moderately active ethylene polymerisation catalysts were found. The catalysts were very unstable and catalyst residues were observed in the isolated polymer indicating a short catalyst lifetime.

Cyclam Derivatives with a Bis(phosphinate) or a Phosphinato-Phosphonate Pendant Arm: Ligands for Fast and Efficient Copper(II) Complexation for Nuclear Medical Applications

Czech Academy of Sciences Publication Activity Database

David, T.; Kubíček, V.; Gutten, Ondrej; Lubal, P.; Kotek, J.; Pietzsch, H.-J.; Rulíšek, Lubomír; Hermann, P.

2015-01-01

Roč. 54, č. 24 (2015), s. 11751-11766 ISSN 0020-1669 R&D Projects: GA ČR(CZ) GA14-31419S Grant - others:COST(XE) TD1004 Institutional support: RVO:61388963 Keywords : cyclam derivatives * radiolabelling * quantum chemical calculations * copper(II) chelation Subject RIV: CA - Inorganic Chemistry Impact factor: 4.820, year: 2015

Surface characteristics, copper release, and toxicity of nano- and micrometer-sized copper and copper(II) oxide particles: a cross-disciplinary study.

OpenAIRE

Midander, Klara; Cronholm, Pontus; Karlsson, Hanna L.; Elihn, Karine; Moller, Lennart; Leygraf, Christofer; Wallinder, Inger Odnevall

2009-01-01

An interdisciplinary and multianalytical research effort is undertaken to assess the toxic aspects of thoroughly characterized nano- and micrometer-sized particles of oxidized metallic copper and copper(II) oxide in contact with cultivated lung cells, as well as copper release in relevant media. All particles, except micrometer-sized Cu, release more copper in serum-containing cell medium (supplemented Dulbecco's minimal essential medium) compared to identical exposures in phosphate-buffered ...

Estudo evolutivo da anatomia das artérias coronárias em espécies de vertebrados com técnica de moldagem em acetato de vinil (vinilite

Directory of Open Access Journals (Sweden)

RODRIGUES Tânia Maria de Andrade

1999-01-01

Full Text Available No presente trabalho foram produzidos 30 moldes anatômicos de corações de vertebrados, visando contribuir para o estudo das artérias coronárias direita e esquerda de diferentes espécies: peixes, anfíbios, répteis, aves e mamíferos. Os corações foram injetados com acetato de vinil, submetidos a corrosão e semicorrosão pelo ácido clorídrico, a fim de evidenciar o padrão anatômico apresentado pelas artérias coronárias no tocante à evolução das espécies e adaptações morfológicas (estrutura e arquitetura. Com base na morfologia das peças estudadas foram obtidas as seguintes conclusões: a técnica utilizando acetato de vinil, associada à corrosão, mostrou-se eficaz na produção de modelos de coração de diferentes espécies, apresentando detalhamento capaz de permitir visibilização dos ramos colaterais, quando existentes; o número de estruturas e a complexidade vascular cardíaca aumenta na medida em que os seres evoluem na escala zoológica. No réptil iguana iguana foi encontrado ventrículo duplo com tríplice via de saída, como único padrão evolutivo da anatomia dos ventrículos e grandes vasos da base ainda não descrito como cardiopatia congênita em humanos.

Síntese de acetato de celulose a partir da palha de feijão utilizando N-bromossuccinimida (NBS como catalisador Synthesis of cellulose acetate from the bean straw using N-bromosuccinimide (NBS as catalyst

Directory of Open Access Journals (Sweden)

Sarah S. Brum

2012-01-01

Full Text Available Neste estudo a celulose obtida da palha de feijão foi utilizada para produzir um material hidrofóbico (acetato de celulose para ser avaliado como absorvente de óleo. Nas reações de acetilação foram utilizados anidrido acético e dois catalisadores, a piridina (PY e N-bromossuccinimida (NBS. Os materiais produzidos foram caracterizados por espectroscopia na região do infravermelho médio, microscopia eletrônica de varredura, difratometria de raios-X e análise elementar. O NBS mostrou-se mais eficiente que a PY e, seu uso resultou em materiais com maiores quantidades de grupos acetatos, mais hidrofóbicos e com maiores capacidades de absorção de óleo de soja.In this work, cellulose from beans straw was used to produce a more hydrophobic material (cellulose acetate for use as oil absorbent. Acetic anhydride was used in the reactions with two catalysts, pyridine (PY and N-bromosuccinimide (NBS. The materials produced were characterized by infrared spectroscopy, scanning electron microscopy, X-ray diffraction and elemental analysis. NBS proved more efficient than PY, with the resulting materials containing higher number of acetate groups, being more hydrophobic and with higher capacity to absorb soybean oil.

Determination of HCl and VOC Emission from Thermal Degradation of PVC in the Absence and Presence of Copper, Copper(II Oxide and Copper(II Chloride

Directory of Open Access Journals (Sweden)

Ahamad J. Jafari

2009-01-01

Full Text Available Polyvinyl chloride (PVC has played a key role in the development of the plastic industry over the past 40 years. Thermal degradation of PVC leads to formation of many toxic pollutants such as HCl, aromatic and volatile organic carbon vapors. Thermal degradation of PVC and PVC in the present of copper, cupric oxide and copper(II chloride were investigated in this study using a laboratory scale electrical furnace. HCl and Cl- ion were analyzed by a Dionex ion chromatograph and VOCs compounds were analyzed using GC or GC-MS. The results showed that HCl plus Cl- ion and benzene formed about 99% and 80% respectively in the first step of thermal degradation under air atmosphere. The presence of cupric oxide increases the percentage of short chain hydrocarbons more than 184% and decreases the amount of the major aromatic hydrocarbon and HCl plus Cl- ion to 90% and 65% respectively. The total aromatic hydrocarbon emitted less than when atmosphere was air and difference was statistically significant (Pvalue<0.000

Caracterização de acetato de celulose obtido a partir do bagaço de cana-de-açúcar por ¹H-RMN 1H-NMR characterization of cellulose acetate obtained from sugarcane bagasse

Directory of Open Access Journals (Sweden)

Daniel A. Cerqueira

2010-06-01

Full Text Available A celulose do bagaço de cana-de-açúcar foi usada para sintetizar acetato de celulose com diferentes graus de substituição, os quais foram caracterizados por ¹H-RMN através da relação entre as áreas dos picos dos átomos de hidrogênio presentes nos grupos acetato (-(C=OOCH3 e os picos dos hidrogênios ligados aos átomos de carbono dos anéis glicosídicos. A supressão de alguns sinais foi feita para remover sinais de ressonância da água residual nos materiais e também para remover sinais de impurezas no triacetato de celulose. Um método de deconvolução para o cálculo computacional do grau de substituição foi proposto. Os graus de substituição das amostras de acetato de celulose foram 2,94 e 2,60, o que está de acordo com os resultados por determinação química através de uma titulação ácido base.Cellulose from sugarcane bagasse was used for synthesizing cellulose acetate with different degrees of substitution, which were characterized by ¹H-NMR through the relationship between the peak areas of the hydrogen atoms of the acetate groups (-(C=OOCH3 and the peaks of the hydrogen bonded to the carbon atoms of the glucosidic rings. Suppression of some signals was carried out in order to remove the residual water resonance in the materials and those related to impurities in cellulose triacetate as well. A deconvolution method for the computation of the degree of substitution of acetylation is proposed. The degrees of substitution for the cellulose samples were 2.94 and 2.60, in good agreement with those obtained by chemical determination through an acid-base titration.

A bipyridine-ligated zinc(II) complex with bridging flavonolate ligation: synthesis, characterization, and visible-light-induced CO release reactivity.

Science.gov (United States)

Sorenson, Shayne; Popova, Marina; Arif, Atta M; Berreau, Lisa M

2017-09-01

Metal-flavonolate compounds are of significant current interest as synthetic models for quercetinase enzymes and as bioactive compounds of importance to human health. Zinc-3-hydroxyflavonolate compounds, including those of quercetin, kampferol, and morin, generally exhibit bidentate coordination to a single Zn II center. The bipyridine-ligated zinc-flavonolate compound reported herein, namely bis(μ-4-oxo-2-phenyl-4H-chromen-3-olato)-κ 3 O 3 :O 3 ,O 4 ;κ 3 O 3 ,O 4 :O 3 -bis[(2,2'-bipyridine-κ 2 N,N')zinc(II)] bis(perchlorate), {[Zn 2 (C 15 H 9 O 3 ) 2 (C 10 H 8 N 2 ) 2 ](ClO 4 ) 2 } n , (1), provides an unusual example of bridging 3-hydroxyflavonolate ligation in a dinuclear metal complex. The symmetry-related Zn II centers of (1) exhibit a distorted octahedral geometry, with weak coordination of a perchlorate anion trans to the bridging deprotonated O atom of the flavonolate ligand. Variable-concentration conductivity measurements provide evidence that, when (1) is dissolved in CH 3 CN, the complex dissociates into monomers. 1 H NMR resonances for (1) dissolved in d 6 -DMSO were assigned via HMQC to the H atoms of the flavonolate and bipyridine ligands. In CH 3 CN, (1) undergoes quantitative visible-light-induced CO release with a quantum yield [0.004 (1)] similar to that exhibited by other mononuclear zinc-3-hydroxyflavonolate complexes. Mass spectroscopic identification of the [(bpy) 2 Zn(O-benzoylsalicylate)] + ion provides evidence of CO release from the flavonol and of ligand exchange at the Zn II center.

Synthesis, thermogravimetric study and crystal structure of an N-rich copper(II) compound with tren ligands and nitrate counter-anions

Energy Technology Data Exchange (ETDEWEB)

Pérez-Toro, Inmaculada; Domínguez-Martín, Alicia [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, 18071 Granada (Spain); Choquesillo-Lazarte, Duane [Laboratorio de Estudios Cristalográficos, IACT, CSIC-Universidad de Granada, Av. de las Palmeras 4, E-18100 Armilla, Granada (Spain); Vílchez-Rodríguez, Esther [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, 18071 Granada (Spain); Department of Inorganic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Castiñeiras, Alfonso [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, 15782 Santiago de Compostela (Spain); Niclós-Gutiérrez, Juan, E-mail: jniclos@ugr.es [Department of Inorganic Chemistry, Faculty of Pharmacy, University of Granada, 18071 Granada (Spain)

2014-10-10

The N-rich salt [{Cu(tren)}{sub 3}(μ{sub 3}-tren)]{sub 2}(NO{sub 3}){sub 12}·3H{sub 2}O has been studied by XRD and by coupled TG and FT-IR spectroscopy of the evolved gases. After water loss, thermal decomposition of the nitrate ions and some tren ligands in the salt are overlapped. - Highlights: • A novel N-rich copper(II)-tren complex has been crystallized as a 3-hydrated nitrate salt. • Tren acts both as tripodal tetradentate and as μ{sub 3}-tren bridging ligand. • Copper(II) centers exhibit distorted trigonal bipyramidal coordination. • Coupled thermogravimetry and FT-IR spectra of evolved gases have been used. • Decomposition of nitrate anions and tren ligands occurs in an overlapped step. - Abstract: The compound [{Cu(tren)}{sub 3}(μ3-tren)]{sub 2}(NO{sub 3}){sub 12}·3H{sub 2}O has been synthesized, crystallized and characterized by single crystal X-ray diffraction, thermogravimetry (TG) coupled to FT-IR spectroscopy of the evolved gases, TG–differential scanning calorimetry (DSC) and electronic (diffuse reflectance) and FT-IR spectroscopies. The sample loses the crystallization water between room temperature and 200 °C. The decomposition of the salt begins with an overlapped decomposition of nitrate anions and some tren ligands where CO{sub 2}, H{sub 2}O, CO, NH{sub 3}, N{sub 2}O, NO and NO{sub 2} are evolved (205–235 °C). Then decomposition of additional tren ligands takes place (235–725 °C). Finally a non-pure CuO residue is obtained at 725 °C.

Efeitos do Implante Subdérmico de Acetato de Nomegestrol sobre o Metabolismo de Carboidratos, Lipoproteínas Séricas e Função Hepática

OpenAIRE

Barbosa, Ione Cristina; Coutinho, Elsimar Metzker; Athayde, Celia; Ladipo, Oladapo; Olsson, Sven-Eric; Ulmsten, Ulf

1998-01-01

Objetivos: avaliar variações de peso corporal, pressão arterial, glicemia em jejum, HbA1C, insulina, colesterol total, HDL-C, LDL-C, triglicérides, TGO, TGP, GGT e bilirrubina em mulheres usuárias de um implante único, subdérmico, de Silástico, contendo 55 mg (±10%) de acetato de nomegestrol, durante dois anos. Métodos: dezoito voluntárias saudáveis e em idade reprodutiva, que desejavam fazer uso de anticoncepcionais e não apresentavam contra-indicações para o uso de contracepção hormonal,...

Adsorption of lead(II) and copper(II) on activated carbon by complexation with surface functional groups

International Nuclear Information System (INIS)

Pesavento, Maria; Profumo, Antonella; Alberti, Giancarla; Conti, Fabio

2003-01-01

The adsorption of lead(II) and copper(II) on an activated carbon (Filtrasorb 300, Chemviron) was characterized assuming that it takes place by formation of complexes with functional groups, present in the activated carbon. Their concentration and conditional adsorption coefficients were determined for each metal by titration of the carbon in suspension in aqueous phase, at constant acidity, with the metal itself. For each titration point, the concentration of the metal in the solution phase after equilibration was determined, and the data were processed by the Ruzic linearization method, to obtain the concentration of the active sites involved in the sorption, and the conditional constant. The effect of the pH was also examined, in the range 4-6, obtaining that the adsorption increases at increasing pH. The protonation and adsorption constants were determined from the conditional adsorption coefficients obtained at the different acidities. The concentration of the active sites is 0.023 and 0.042 mmol g -1 , and the protonation constants are 1.0x10 6 and 4.6x10 4 M -1 for Pb(II) and Cu(II). The corresponding adsorption constants are respectively 1.4x10 5 and 6.3x10 3 M -1 . All the parameters are affected by a large uncertainty, probably due to the heterogeneity of the active groups in the activated carbon. Even if so, these parameters make it possible a good prediction of the adsorption in a wide range of conditions. Other sorption mechanism can be set up at different conditions, in particular at different pH, as it has been demonstrated in the case of copper(II)

Adsorption of lead(II) and copper(II) on activated carbon by complexation with surface functional groups

Energy Technology Data Exchange (ETDEWEB)

Pesavento, Maria; Profumo, Antonella; Alberti, Giancarla; Conti, Fabio

2003-03-17

The adsorption of lead(II) and copper(II) on an activated carbon (Filtrasorb 300, Chemviron) was characterized assuming that it takes place by formation of complexes with functional groups, present in the activated carbon. Their concentration and conditional adsorption coefficients were determined for each metal by titration of the carbon in suspension in aqueous phase, at constant acidity, with the metal itself. For each titration point, the concentration of the metal in the solution phase after equilibration was determined, and the data were processed by the Ruzic linearization method, to obtain the concentration of the active sites involved in the sorption, and the conditional constant. The effect of the pH was also examined, in the range 4-6, obtaining that the adsorption increases at increasing pH. The protonation and adsorption constants were determined from the conditional adsorption coefficients obtained at the different acidities. The concentration of the active sites is 0.023 and 0.042 mmol g{sup -1}, and the protonation constants are 1.0x10{sup 6} and 4.6x10{sup 4} M{sup -1} for Pb(II) and Cu(II). The corresponding adsorption constants are respectively 1.4x10{sup 5} and 6.3x10{sup 3} M{sup -1}. All the parameters are affected by a large uncertainty, probably due to the heterogeneity of the active groups in the activated carbon. Even if so, these parameters make it possible a good prediction of the adsorption in a wide range of conditions. Other sorption mechanism can be set up at different conditions, in particular at different pH, as it has been demonstrated in the case of copper(II)

Treatment of model and galvanic waste solutions of copper(II) ions using a lignin/inorganic oxide hybrid as an effective sorbent.

Science.gov (United States)

Ciesielczyk, Filip; Bartczak, Przemysław; Klapiszewski, Łukasz; Jesionowski, Teofil

2017-04-15

A study was made concerning the removal of copper(II) ions from model and galvanic waste solutions using a new sorption material consisting of lignin in combination with an inorganic oxide system. Specific physicochemical properties of the material resulted from combining the activity of the functional groups present in the structure of lignin with the high surface area of the synthesized oxide system (585m 2 /g). Analysis of the porous structure parameters, particle size and morphology, elemental composition and characteristic functional groups confirmed the effective synthesis of the new type of sorbent. A key element of the study was a series of tests of adsorption of copper(II) ions from model solutions. It was determined how the efficiency of the adsorption process was affected by the process time, mass of sorbent, concentration of adsorbate, pH and temperature. Potential regeneration of adsorbent, which provides the possibility of its reusing and recovering the adsorbed copper, was also analyzed. The sorption capacity of the material was measured (83.98mg/g), and the entire process was described using appropriate kinetic models. The results were applied to the design of a further series of adsorption tests, carried out on solutions of real sewage from a galvanizing plant. Copyright © 2017 Elsevier B.V. All rights reserved.

The Akashi Kaikyo Bridge and the Storebælt Bridge

DEFF Research Database (Denmark)

Gimsing, Niels Jørgen

1999-01-01

With the completion of the Akashi Kaikyo Bridge and the Storebælt East Bridge the development of the suspension bridge technology in the 20th century has manifested itself in two impressive structures. With the present echnology may bridges of similar (and also more modest) dimensions...... will undoubtedly be built far into the next century. For bridges going beyond the spans of existing bridges it is, however, likely that new concepts will be developed....

Antioxidant, DNA interaction, VEGFR2 kinase, topoisomerase I and in vitro cytotoxic activities of heteroleptic copper(II) complexes of tetrazolo[1,5-a]pyrimidines and diimines

Energy Technology Data Exchange (ETDEWEB)

Haleel, A.; Mahendiran, D. [Post-Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai 600 014 (India); Veena, V.; Sakthivel, N. [Department of Biotechnology, Pondicherry University, Pondicherry 605 014 (India); Rahiman, A. Kalilur, E-mail: akrahmanjkr@gmail.com [Post-Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai 600 014 (India)

2016-11-01

A series of heteroleptic mononuclear copper(II) complexes of the type [Cu(L{sup 1–3})(diimine)]ClO{sub 4} (1–6) containing three tetrazolo[1,5-a]pyrimidine core ligands, ethyl 5-methyl-7-(2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a] pyrimidine-6-carboxylate (HL{sup 1}), ethyl 5-methyl-7-(4-diethylamino-2-hydroxyphenyl)-4,7-dihydrotetrazolo[1,5-a] pyrimidine-6-carboxylate (HL{sup 2}) or ethyl 5-methyl-7-(2-hydroxy-4-nitrophenyl)-4,7-dihydrotetrazolo[1,5-a] pyrimidine-6-carboxylate (HL{sup 3}), and two diimine coligands, 2,2′-bipyridyl (bpy) or 1,10-phenanthroline (phen) have been synthesized and characterized by spectral methods. The geometry of complexes have been determined with the help of electronic absorption and EPR splitting patterns, which suggest four coordinated square planar geometry around copper(II) ion. The lowering of HOMO–LUMO band gap value of complex 4 implies its higher biological activity compared to other complexes. Antioxidant studies revealed that the complexes possess considerable radical scavenging potency against DPPH. The binding studies of the complexes with calf thymus DNA (CT–DNA) revealed groove mode of binding, which was further supported by docking simulation. The complexes 3 and 4 strongly inhibit the topoisomerase I, and also strongly interact with VEGFR2 kinase receptor via π–π, σ–π and hydrogen bonding interaction. Gel electrophoresis experiments demonstrated the ability of the complexes to cleave plasmid DNA in the absence of activators. In vitro cytotoxic activities of the complexes were examined on three cancerous cell lines such as human lung (A549), cervical (HeLa) and colon (HCT-15), and two normal cells such as human embryonic kidney (HEK) and peripheral blood mononuclear cells (PBMCs). The live cell and fluorescent imaging of cancer cells were observed with acridine orange/ethidium bromide staining assay. All encouraging chemical and biological findings indicate that the complex 4 is a suitable candidate

Bridge Management Systems

DEFF Research Database (Denmark)

Thoft-Christensen, Palle

In this paper bridge management systems are discussed with special emphasis on management systems for reinforced concrete bridges. Management systems for prestressed concrete bridges, steel bridges, or composite bridges can be developed in a similar way....

Magnetic interactions through fluoride

DEFF Research Database (Denmark)

Pedersen, Kasper Steen; Sigrist, Marc; Weihe, Høgni

2014-01-01

support the parameter values and resolve |E| ≈ 0.04 cm(-1). The exchange coupling constant (J) is 1 order of magnitude smaller than that found in comparable systems with linear oxide bridging but comparable to typical magnitudes through cyanide, thus underlining the potential of fluoride complexes......The nature of the magnetic interaction through fluoride in a simple, dinuclear manganese(III) complex (1), bridged by a single fluoride ion in a perfectly linear fashion, is established by experiment and density functional theory. The magnitude of the antiferromagnetic exchange interaction...

A [Mo{sub 2}O{sub 2}S{sub 2}]-based ring system incorporating tartrate as the bridging ligand. Synthesis, structure and catalytic activity of Cs{sub 4}[Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sub 2}(μ{sub 4}-tart){sub 2} (tart=[C{sub 4}H{sub 2}O{sub 6}]{sup 4-})

Energy Technology Data Exchange (ETDEWEB)

Qian, Ting-Ting; Cui, Yu-Jie; Xin, Zhifeng; Jia, Ai-Quan; Zhang, Qian-Feng [Anhui Univ. of Technology, Anhui (China). Inst. of Molecular Engineering and Applied Chemistry and Anhui Province Key Lab. of Metallurgy Engineering and Resources Recycling

2017-08-01

Treatment of [Mo{sub 2}S{sub 2}O{sub 2}(H{sub 2}O){sub 6}]{sup 2+} with racemic tartaric acid (tartH{sub 4}) in the presence of sodium hydroxide and cesium chloride in aqueous solution led to the isolation of a new tetra-molybdenum ring cluster Cs{sub 4}[Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sub 2}(μ{sub 4}-tart){sub 2}. The cyclic cluster polyanion consists of two dinuclear [Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sup 2+} moieties and two bridging tart{sup 4-} ligands. The cyclic polyoxothiomolybdate cluster, supported on the mesoporous silica SBA-15, was tested for heterogenerous catalysis in thiophene hydrodesulfurization.

Blue-emitting dinuclear N-heterocyclic dicarbene gold(I) complex featuring a nearly unit quantum yield

KAUST Repository

Baron, Marco

2012-02-06

Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au 2(RIm-Y-ImR) 2](PF 6) 2 (R = Me, Cy; Y = (CH 2) 1-4, o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH 2) 3 exhibit an intense blue emission (λ max = 450 nm) with a high quantum yield (Φ em = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au•••Au distance (3.272 Ǻ). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au•••Au distance. © 2012 American Chemical Society.

Blue-emitting dinuclear N-heterocyclic dicarbene gold(I) complex featuring a nearly unit quantum yield

KAUST Repository

Baron, Marco; Tubaro, Cristina; Biffis, Andrea; Basato, Marino; Graiff, Claudia; Poater, Albert; Cavallo, Luigi; Armaroli, Nicola; Accorsi, Gianluca

2012-01-01

Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au 2(RIm-Y-ImR) 2](PF 6) 2 (R = Me, Cy; Y = (CH 2) 1-4, o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH 2) 3 exhibit an intense blue emission (λ max = 450 nm) with a high quantum yield (Φ em = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au•••Au distance (3.272 Ǻ). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au•••Au distance. © 2012 American Chemical Society.

Synthesis, crystal structure and magnetic properties of [Cu(mal)(abpt ...

African Journals Online (AJOL)

Complex 1 consist of a neutral mononuclear [Cu(mal)(abpt)(H2O)] unit and water molecule of crystallization in a distorted square pyramidal coordination sphere, while complex 2 is viewed as being made up of [Cu(sq)(abpt)2] units with the squarato ligand bridging the two copper(II) cations. Variable temperature magnetic ...

Efeitos do implante subdérmico de acetato de nomegestrol sobre o metabolismo de carboidratos, lipoproteínas séricas e função hepática

OpenAIRE

Barbosa,Ione; Coutinho,Elsimar; Athayde,Célia; Ladipo,Oladapo; Olsson,Sven-Eric; Ulmsten,Ulf

1998-01-01

Objetivos: avaliar variações de peso corporal, pressão arterial, glicemia em jejum, HbA1C, insulina, colesterol total, HDL-C, LDL-C, triglicérides, TGO, TGP, GGT e bilirrubina em mulheres usuárias de um implante único, subdérmico, de Silástico, contendo 55 mg (±10%) de acetato de nomegestrol, durante dois anos. Métodos: dezoito voluntárias saudáveis e em idade reprodutiva, que desejavam fazer uso de anticoncepcionais e não apresentavam contra-indicações para o uso de contracepção hormonal, pa...

Railroad Bridges

Data.gov (United States)

Department of Homeland Security — Bridges-Rail in the United States According to The National Bridge Inspection Standards published in the Code of Federal Regulations (23 CFR 650.3), a bridge isA...

Copper(II) complexes of alloferon 1 with point mutations (H1A) and (H9A) stability structure and biological activity.

Science.gov (United States)

Matusiak, Agnieszka; Kuczer, Mariola; Czarniewska, Elżbieta; Rosiński, Grzegorz; Kowalik-Jankowska, Teresa

2014-09-01

Mono- and polynuclear copper(II) complexes of the alloferon 1 with point mutations (H1A) A(1)GVSGH(6)GQH(9)GVH(12)G (Allo1A) and (H9A) H(1)GVSGH(6)GQA(9)GVH(12)G (Allo9A) have been studied by potentiometric, UV-visible, CD, EPR spectroscopic and mass spectrometry (MS) methods. To obtain a complete complex speciation different metal-to-ligand molar ratios ranging from 1:1 to 4:1 for Allo1A and to 3:1 for Allo9A were studied. The presence of the His residue in first position of the peptide chain changes the coordination abilities of the Allo9A peptide in comparison to that of the Allo1A. Imidazole-N3 atom of N-terminal His residue of the Allo9A peptide forms stable 6-membered chelate with the terminal amino group. Furthermore, the presence of two additional histidine residues in the Allo9A peptide (H(6),H(12)) leads to the formation of the CuL complex with 4N {NH2,NIm-H(1),NIm-H(6),NIm-H(12)} binding site in wide pH range (5-8). For the Cu(II)-Allo1A system, the results demonstrated that at physiological pH7.4 the predominant complex the CuH-1L consists of the 3N {NH2,N(-),CO,NIm} coordination mode. The inductions of phenoloxidase activity and apoptosis in vivo in Tenebrio molitor cells by the ligands and their copper(II) complexes at pH7.4 were studied. The Allo1A, Allo1K peptides and their copper(II) complexes displayed the lowest hemocytotoxic activity while the most active was the Cu(II)-Allo9A complex formed at pH7.4. The results may suggest that the N-terminal-His(1) and His(6) residues may be more important for their proapoptotic properties in insects than those at positions 9 and 12 in the peptide chain. Copyright © 2014 Elsevier Inc. All rights reserved.

Implementation of Bridge Management System on Interurban Bridge in Maluku Province

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Erwin Marasabessy

2015-05-01

Full Text Available Bridges as transport infrastructures play a vital role in smoothing traffic flows. The success of a bridge in playing its role and serving its function depends on its management. The Directorate General of Highways of the Ministry of Public Work has used a system to manage bridges known as the Bridge Management System (BMS. The system allows a systematic plan and provides a uniform procedure for all bridge operation activities on the national and provincial level. Data from Implementation Agency of National Inter-Urban Roads of Area IX, Northern Maluku in 2011 indicates that the total length of national roads in Maluku Province is 15,238.01 M, with a total of 562 bridges. In Ambon Island, especially, there are 52 bridges totaling 1,176.25 m in length. The study was conducted at several inter-urban bridges in Maluku Province of Ambon Island: Wai Batu Merah, Wai Ruhu, Wai Lawa, Wai Yari and Wai Tua bridges. Assessment of bridge structure conditions was conducted visually to determine the conditions of the existing bridges comprehensively by referring to the Bridge Management System (BMS complemented with a computer-based Bridge Management Information System (BMIS. Condition scores for the five bridges—Wai Batu Merah, Wai Ruhu, Wai Lawa, Wai Yari, and Wai Tua, according to Bridge Management System, are 2, 1, 2, 1, and 2 respectively. The scores of the five bridges indicate that their physical condition can be categorized as good or with minor defects. Based on technical screening, the proposed treatment for Wai Batu Merah, Wai Ruhu, Wai Lawa, dan Wai Tua bridges is the rehabilitation of their sub-elements. As for the Wai Yari Bridge, the treatment will be maintained regularly. The defect repair costs are IDR 149,138,238.00, IDR 81,048,000.00, IDR 174,579,106.10, IDR 79,233,324.01 and IDR 238,323,258.60 for Wai Batu, Wai Ruhu, Wai Lawa, Wai Yari, and Wai Tua Bridges, respectively.

Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

KAUST Repository

Dehury, Niranjan

2016-07-18

Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction involving transfer hydrogenation of fluoroarylketone to the corresponding alcohol and Suzuki-Miyaura cross coupling reaction of the resulting fluoroarylalcohol under moderate reaction conditions, to biaryl alcohol. The complex with the shortest Pd-Pd distance exhibits the highest tandem activity among its di-metallic analogues, and exceeds in terms of activity and selectivity the analogous mononuclear compound. The kinetics of the reaction indicates clearly that reductive transformation of haloarylketone into haloaryalcohol is the rate determining step in the tandem reaction. Interestingly while fluoroarylketone undergoes the multistep tandem catalysis, the chloro- and bromo-arylketones undergo only a single step C-C coupling reaction resulting in biarylketone as the final product. Unlike the pyrazole based Pd compounds, the precursor PdCl2 and the phosphine based relevant complexes (PPh3)2PdCl2 and (PPh3)4Pd are found to be unable to exhibit the tandem catalysis.

Multitarget trehalose-carnosine conjugates inhibit Aβ aggregation, tune copper(II) activity and decrease acrolein toxicity.

Science.gov (United States)

Grasso, Giuseppa Ida; Bellia, Francesco; Arena, Giuseppe; Satriano, Cristina; Vecchio, Graziella; Rizzarelli, Enrico

2017-07-28

Increasing evidence is accumulating, showing that neurodegenerative disorders are somehow associated with the toxicity of amyloid aggregates, metal ion dyshomeostasis as well as with products generated by oxidative stress. Within the biological oxidation products, acrolein does have a prominent role. A promising strategy to deal with the above neurogenerative disorders is to use multi-functions bio-molecules. Herein, we show how a class of bio-conjugates takes advantage of the antiaggregating, antioxidant and antiglycating properties of trehalose and carnosine. Their ability to sequester acrolein and to inhibit both self- and metal-induced aggregation is here reported. The copper(II) coordination properties of a new trehalose-carnosine conjugate and the relative antioxidant effects have also been investigated. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Desempeño del método cromatográfico para el estudio de estabilidad del aceite de hígado de tiburón microencapsulado empleando acetato de quitosana

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Caridad García

Full Text Available Objetivo: Evaluar el desempeño del método para la cuantificación de la vitamina A en el aceite microencapsulado, empleando acetato de quitosana y maltodextrina como agentes encapsulantes, así como estudiar la estabilidad del aceite microencapsulado. Materiales y métodos: Los parámetros evaluados se correspondieron con lo establecido internacionalmente para este estudio: especificidad, exactitud y precisión. El estudio de estabilidad se realizó durante 12 meses a temperatura ambiente (30 ± 2ºC y 70 ± 5 % de humedad relativa, evaluándose en el tiempo la eficiencia de encapsulación, aceite superficial, pérdidas por desecación, contenido de vitamina A y conteo microbiológico. Resultados: Se demostró que el método evaluado fue específico, preciso y exacto para la determinación del contenido de vitamina A en la mezcla de aceite microencapsulado. Los resultados demuestran que el aceite microencapsulado tiene un comportamiento estable en cuanto a los indicadores evaluados, evidenciándose la protección ofrecida por los componentes de la pared de las microcápsulas. Conclusiones: El método empleado en la cuantificación de la vitamina A en el aceite microencapsulado resultó específico, exacto y preciso, demostrándose su aplicabilidad para el control de calidad y estudio de estabilidad. El aceite microencapsulado con acetato de quitosana y maltodextrina como agentes encapsulantes, es estable física, química y microbiológicamente, durante 12 meses.

Synthesis, Hirshfeld surface analyses and magnetism of a 1D Mn(II ...

African Journals Online (AJOL)

A new Mn-based complex of {[Mn(L)2(mi)]·H2O}n (1) (HL = p-hydroxy phenylacetic acid; mi = 1,1'-(1,4-butanediyl)bis(imidazole)), has been synthesized and structurally characterized. Single-crystal X-ray analyses reveal that compound 1 has a dinuclear Mn(II) unit linking by four carboxylate groups. The bridging N-donor ...

Long-term bridge performance high priority bridge performance issues.

Science.gov (United States)

2014-10-01

Bridge performance is a multifaceted issue involving performance of materials and protective systems, : performance of individual components of the bridge, and performance of the structural system as a whole. The : Long-Term Bridge Performance (LTBP)...

Complexes cobalt(II, zinc(II and copper(II with some newly synthesized benzimidazole derivatives and their antibacterial activity

Directory of Open Access Journals (Sweden)

S. O. PODUNAVAC-KUZMANOVIC

1999-05-01

Full Text Available The preparation and properties of some complexes of cobalt(II, zinc(II and copper(II with several newly synthesized benzimidazole derivatives (L are reported. The complexes, of the general formula [MCl2L2] (M=Co(II, Zn(II and [CuCl2L(H2O], have a tetrahedral structure. The complexes were characterized by elemental analysis, molar conductivity, magnetic susceptibility measurements, IR and absorption electronic spectra. The antibacterial activitiy of the benzimidazoles and their complexes was evaluated against Erwinia carotovora subsp. carotovora and Erwinia amylovora. The complexes were found to be more toxic than the ligands.

MÉTODO EXTENDIDO DE HILDEBRAND EN LA ESTIMACIÓN DE LA SOLUBILIDAD DE LA INDOMETACINA EN MEZCLAS ACETATO DE ETILO + ETANOL

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Miller Ruidiaz

2010-03-01

Full Text Available La indometacina (IMC es un anti-inflamatorio no esteroidal de amplio uso en la actualidad, sin embargo, sus propiedades fisicoquímicas aún no han sido estudiadas en su totalidad. En la presente investigación, se aplicó el método extendido de solubilidad de Hildebrand (MESH al estudio de la solubilidad de la IMC en mezclas binarias acetato de etilo + etanol a 298,15 K. Se obtuvo una adecuada capacidad predictiva del MESH al utilizar un modelo polinómico regular de quinto orden, relacionando el parámetro de interacciónWcon el parámetro de solubilidad de las mezclas solventes. Sin embargo, las desviaciones obtenidas en la solubilidad estimada, fueron de magnitud semejante a las obtenidas al calcular esta propiedad directamente, utilizando una regresión empírica regular del mismo orden, de la solubilidad experimental del fármaco en función del parámetro de solubilidad de las mezclas disolventes.

Chemistry of the uranyl group

International Nuclear Information System (INIS)

Zarli, B.; Dall'olio, G.; Sindellari, L.

1976-01-01

Some uranyl complexes with hexamethylphosphoramide (HMPA) and urea were prepared and characterized. The compounds with the former ligand have the general formula UO 2 X 2 .HMPA (where X = (C 2 H 5 ) 2 NCSe 2 - , (C 2 H 5 ) 2 NCS 2 - or CH 3 COO - ). For the acetato derivatives a dimeric acetato-bridged structure is suggested. Some properties of UO 2 (NO 3 ) 2 .2(HMPA) are also described. With the latter ligand, in addition to the complexes UO 2 (NO 3 ) 2 .2urea and [UO 2 (urea) 4 (H 2 0)](NO 3 ) 2 already known, the novel complexes UO 2 (pycrate) 2 .4urea and [UO 2 (CH 3 COO) 2 .urea]sub(n) (where n is probably 2) have been prepared. All attempts to obtain urea complexes of uranyl diethyldithio- or diethyldiselenocarbamate failed and only adducts of unsatisfactory stoichiometry were isolated. (author)

A Nanostructured Lipid System as a Strategy to Improve the in Vitro Antibacterial Activity of Copper(II Complexes

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Patricia B. da Silva

2015-12-01

Full Text Available The aim of this study was to construct a nanostructured lipid system as a strategy to improve the in vitro antibacterial activity of copper(II complexes. New compounds with the general formulae [CuX2(INH2]·nH2O (X = Cl− and n = 1 (1; X = NCS− and n = 5 (2; X = NCO− and n = 4 (3; INH = isoniazid, a drug widely used to treat tuberculosis derived from the reaction between the copper(II chloride and isoniazid in the presence or absence of pseudohalide ions (NCS− or NCO− were synthesized and characterized by infrared spectrometry, electronic absorption spectroscopy, electron paramagnetic resonance (EPR spectroscopy, elemental analysis, melting points and complexometry with 2,2′,2′′,2′′′-(Ethane-1,2-diyldinitrilotetraacetic acid (EDTA. The characterization techniques allowed us to confirm the formation of the copper(II complexes. The Cu(II complexes were loaded into microemulsion (MEs composed of 10% phase oil (cholesterol, 10% surfactant [soy oleate and Brij® 58 (1:2] and 80% aqueous phase (phosphate buffer pH = 7.4 prepared by sonication. The Cu(II complex-loaded MEs displayed sizes ranging from 158.0 ± 1.060 to 212.6 ± 1.539 nm, whereas the polydispersity index (PDI ranged from 0.218 ± 0.007 to 0.284 ± 0.034. The antibacterial activity of the free compounds and those that were loaded into the MEs against Staphylococcus aureus ATCC® 25923 and Escherichia coli ATCC® 25922, as evaluated by a microdilution technique, and the cytotoxicity index (IC50 against the Vero cell line (ATCC® CCL-81TM were used to calculate the selectivity index (SI. Among the free compounds, only compound 2 (MIC 500 μg/mL showed activity for S. aureus. After loading the compounds into the MEs, the antibacterial activity of compounds 1, 2 and 3 was significantly increased against E. coli (MIC’s 125, 125 and 500 μg/mL, respectively and S. aureus (MICs 250, 500 and 125 μg/mL, respectively. The loaded compounds were less toxic against the Vero

Copper(II) and palladium(II) complexes with tridentate NSO donor Schiff base ligand: Synthesis, characterization and structures

Science.gov (United States)

Kumar, Sujit Baran; Solanki, Ankita; Kundu, Suman

2017-09-01

Mononuclear copper(II) complex [CuL2] and palladium(II) complexes [Pd(X)L] where X = benzoate(bz) or salicylate(sal) and HL = 2-(methylthio)phenylimino)methyl)phenol, a Schiff base ligand with NSO coordination sites have been synthesized and characterized by microanalyses, IR, UV-Visible spectra, conductivity measurement and magnetic studies. Crystal structures of all the complexes have been solved by single crystal X-ray diffraction studies and showed that there are two molecules in a unit cell in the [CuL2] complex - one molecule has square planar geometry whereas second molecule has distorted square pyramidal geometry and palladium(II) complexes have distorted square planar geometry.

A serials of sandwich-like trinuclear and one-dimensional chain cyanide-bridged iron(III)-copper(II) complexes: Syntheses, crystal structures and magnetic properties

Science.gov (United States)

Shi, Jingwen; Lan, Wenlong; Ren, Yanjie; Liu, Qingyun; Liu, Hui; Dong, Yunhui; Zhang, Daopeng

2018-04-01

Four pyridinecarboxamide trans-dicyanideiron(III) building blocks and one macrocyclic copper(II) compound have been employed to assemble cyanide-bridged heterometallic complexes, resulting in a serials of cyanide-bridged FeIII-CuII complexes with different structure types. The series of complexes can be formulated as: {[Cu(Cyclam)][Fe(bpb)(CN)2]2}·4H2O (1), {{[Cu(Cyclam)][Fe(bpb)(CN)2]}ClO4}n·nH2O (2), and {[Cu(Cyclam)][Fe(bpmb)(CN)2]2}·4H2O (3), {[Cu(Cyclam)][Fe(bpClb)(CN)2]2}·4H2O (4) and {{[Cu(Cyclam)][Fe(bpdmb)(CN)2]}ClO4}n·2nCH3OH (5) (bpb2- = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb2- = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpClb2- = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate, bpdmb2- = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, Cyclam = 1,4,8,11-tetraazacyclotetradecane). All the complexes have been characterized by elemental analysis, IR spectra and structural determination. Single X-ray diffraction analysis shows the similar neutral sandwich-like structures for complexes 1, 3 and 4, in which the two cyano precursors acting as monodentate ligand through one of their two cyanide groups were coordinated face to face to central Cu(II) ion. The complexes 2 and 5 can be structurally characterized as one-dimensional cationic single chain consisting of alternating units of [Cu(Cyclam)]2+ and [Fe(bpb/bpdmb)(CN)2]- with free ClO4- as balanced anion. Investigation over magnetic properties of the whole serials of complexes reveals the antiferromagnetic magnetic coupling between the neighboring cyanide-bridged Fe(III) and Cu(II) ions in complexes 3 and 4 and the ferromagnetic interaction in complexes 1, 2 and 5, respectively.

47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Operator requirements of the Bridge-to-Bridge... Requirements § 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the Bridge-to-Bridge Act must have on board a radio operator who holds a restricted radiotelephone operator permit or...

Bridge health monitoring metrics : updating the bridge deficiency algorithm.

Science.gov (United States)

2009-10-01

As part of its bridge management system, the Alabama Department of Transportation (ALDOT) must decide how best to spend its bridge replacement funds. In making these decisions, ALDOT managers currently use a deficiency algorithm to rank bridges that ...

47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.

Science.gov (United States)

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Watch required by the Bridge-to-Bridge Act. 80... Safety Watches § 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch requirement contained in § 80.148, all vessels subject to the Bridge-to-Bridge Act must keep a watch on the designated...

Field performance of timber bridges. 7, Connell Lake stress-laminated deck bridge

Science.gov (United States)

L. E. Hislop; M. A. Ritter

The Connell Lake bridge was constructed in early 1991 on the Tongass National Forest, Alaska, as a demonstration bridge under the Timber Bridge Initiative. The bridge is a stress-laminated deck structure with an approximate 36-ft length and 18-ft width and is the first known stress-laminated timber bridge constructed in Alaska. Performance of the bridge was monitored...

Track-Bridge Longitudinal Interaction of Continuous Welded Rails on Arch Bridge

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Rong Chen

2013-01-01

Full Text Available Taking arch bridges, including deck, half-through, and through arch bridges (short for DAB, HTAB, and TAB as examples, mechanics analysis models of longitudinal interaction between continuously welded rails (short for CWRs and arch bridges are established. Based on the finite element method (FEM, the longitudinal interaction calculation software of CWR on arch bridges has been developed. Focusing on an HTAB, the tension, compression, and deflection conditions are calculated and analyzed. The results show that the mechanics analysis models of three types of arch bridges can truly reflect the real state of the structure; the calculation software can be used for systematic research of the CWR on arch bridge; as for HTAB, temperature difference of arch rib has a small effect on rail tension/compression, and arch bridge can be simplified as a continuous beam for rail tension/compression additional force calculation; in calculation of deflection conditions of HTAB, it is suggested that train loads are arranged on half span and full span and take the direction of load entering bridge into account. Additionally, the deflection additional force variation of CFST basket handle arch bridge is different from that of ordinary bridge.

Modificação do acetato de celulose em meio homogêneo via reações de condensação com diferentes isocianatos Homogeneous chemical modification of cellulose acetate using different isocyanates

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Vagner R. Botaro

1998-01-01

Full Text Available Este estudo descreve uma série de reações envolvendo os grupos isocianatos (NCO e os grupos hidroxílicos do acetato de celulose com grau de substituição (DS igual a 2,4. As reações foram realizadas em meio homogêneo e utilizaram dois isocianatos estruturalmente diferentes: o 3-isopropenil-,'-dimetilbenzil isocianato (TMI e o 2-isocianato-etil metacrilato (IEM. Um acompanhamento cinético das reações foi realizado por espectroscopia na região do infravermelho, onde acompanhou-se o desaparecimento da banda típica de isocianato a aproximadamente 2260 cm-1. Filmes de acetato de celulose modificados foram obtidos após as reações, sendo posteriormente caracterizados por análises de ângulos de contato, espectroscopia na região do infravermelho e ensaios de tração.This investigation describes a series of homogeneous reactions involving the OH groups of cellulose acetate with a DS of 2.4 and two alkenyl isocyanates, viz. 3-isopropyl a,a-dimethylbenzyl isocyanate (TMI and 2-isocyanato-ethyl methacrylate (IEM. The kinetics of these reactions were followed by FTIR spectroscopy by monitoring the decrease in intensity with time of the band around 2260 cm-1. The product of these condensations were isolated as thin films which were characterized by FTIR spectroscopy, surface hydrophilic-hydrophobic evaluation through contact angle measurements and tensile strength.

Synthesis of mononuclear copper(II) complexes of N3O2 and N4O2 donors containing Schiff base ligands: Theoretical and biological observations

Science.gov (United States)

Mancha Madha, K.; Gurumoorthy, P.; Arul Antony, S.; Ramalakshmi, N.

2017-09-01

A new series of six mononuclear copper(II) complexes were synthesized from N3O2 and N4O2 donors containing Schiff base ligands, and characterized by various spectral methods. The geometry of the complexes was determined using UV-Vis, EPR and DFT calculations. The complexes of N3O2 donors (1-3) adopted square pyramidal geometry and the remaining complexes of N4O2 donors (4-6) show distorted octahedral geometry around copper(II) nuclei. Redox properties of the complexes show a one-electron irreversible reduction process in the cathodic potential (Epc) region from -0.74 to -0.98 V. The complexes show potent antioxidant activity against DPPH radicals. Molecular docking studies of complexes showed σ-π interaction, hydrogen bonding, electrostatic and van der Waals interactions with VEGFR2 kinase receptor. In vitro cytotoxicity of the complexes was tested against human breast cancer (MDA-MB-231) cell lines and one normal human dermal fibroblasts (NHDF) cell line through MTT assay. The morphological assessment data obtained by Hoechst 33258 and AO/EB staining revealed that the complexes induce apoptosis pathway of cell death.

Unusual saccharin-N,O (carbonyl) coordination in mixed-ligand copper(II) complexes: Synthesis, X-ray crystallography and biological activity

Science.gov (United States)

Mokhtaruddin, Nur Shuhada Mohd; Yusof, Enis Nadia Md; Ravoof, Thahira B. S. A.; Tiekink, Edward R. T.; Veerakumarasivam, Abhi; Tahir, Mohamed Ibrahim Mohamed

2017-07-01

Three tridentate Schiff bases containing N and S donor atoms were synthesized via the condensation reaction between S-2-methylbenzyldithiocarbazate with 2-acetyl-4-methylpyridine (S2APH); 4-methyl-3-thiosemicarbazide with 2-acetylpyridine (MT2APH) and 4-ethyl-3-thiosemicarbazide with 2-acetylpyridine (ET2APH). Three new, binuclear and mixed-ligand copper(II) complexes with the general formula, [Cu(sac)(L)]2 (sac = saccharinate anion; L = anion of the Schiff base) were then synthesized, and subsequently characterized by IR and UV/Vis spectroscopy as well as by molar conductivity and magnetic susceptibility measurements. The Schiff bases were also spectroscopically characterized using NMR and MS to further confirm their structures. The spectroscopic data indicated that the Schiff bases behaved as a tridentate NNS donor ligands coordinating via the pyridyl-nitrogen, azomethine-nitrogen and thiolate-sulphur atoms. Magnetic data indicated a square pyramidal environment for the complexes and the conductivity values showed that the complexes were essentially non-electrolytes in DMSO. The X-ray crystallographic analysis of one complex, [Cu(sac)(S2AP)]2 showed that the Cu(II) atom was coordinated to the thiolate-S, azomethine-N and pyridyl-N donors of the S2AP Schiff base and to the saccharinate-N from one anion, as well as to the carbonyl-O atom from a symmetry related saccharinate anion yielding a centrosymmetric binuclear complex with a penta-coordinate, square pyramidal geometry. All the copper(II) saccharinate complexes were found to display strong cytotoxic activity against the MCF-7 and MDA-MB-231 human breast cancer cell lines.

New dinuclear palladium(II) complexes: Studies of the nucleophilic substitution reactions, DNA/BSA interactions and cytotoxic activity.

Science.gov (United States)

Ćoćić, Dušan; Jovanović, Snežana; Nišavić, Marija; Baskić, Dejan; Todorović, Danijela; Popović, Suzana; Bugarčić, Živadin D; Petrović, Biljana

2017-10-01

Six new dinuclear Pd(II) complexes, [{Pd(2,2'-bipy)Cl} 2 (μ-pz)](ClO 4 ) 2 (Pd1), [{Pd(dach)Cl} 2 (μ-pz)](ClO 4 ) 2 (Pd2), [{Pd(en)Cl} 2 (μ-pz)](ClO 4 ) 2 (Pd3), [{Pd(2,2'-bipy)Cl} 2 (μ-4,4'-bipy)](ClO 4 ) 2 (Pd4), [{Pd(dach)Cl} 2 (μ-4,4'-bipy)](ClO 4 ) 2 (Pd5) and [{Pd(en)Cl} 2 (μ-4,4'-bipy)](ClO 4 ) 2 (Pd6) (where 2,2'-bipy=2,2'-bipyridyl, pz=pyrazine, dach=trans-(±)-1,2-diaminocyclohexane, en=ethylenediamine, 4,4'-bipy=4,4'-bipyridyl) have been synthesized and characterized by elemental microanalysis, IR, 1 H NMR and MALDI-TOF mass spectrometry. The pK a values of corresponding diaqua complexes were determined by spectrophotometric pH titration. Substitution reactions with thiourea (Tu), l-methionine (l-Met), l-cysteine (l-Cys), l-histidine (l-His) and guanosine-5'-monophosphate (5'-GMP) were studied under the pseudo-first order conditions at pH7.2. Reactions of Pd1 with Tu, l-Met and l-Cys were followed by decomposition of complexes, while structures of dinuclear complexes were preserved during the substitution with nitrogen donors. Interactions with calf-thymus DNA (CT-DNA) were followed by absorption spectroscopy and fluorescence quenching measurements. All complexes can bind to CT-DNA exhibiting high intrinsic binding constants (K b =10 4 -10 5 M -1 ). Competitive studies with ethidium bromide (EB) have shown that complexes can displace DNA-bound EB. High values of binding constants towards bovine serum albumin protein (BSA) indicate good binding affinity. Finally, all complexes showed moderate to high cytotoxic activity against HeLa (human cervical epithelial carcinoma cell lines) and MDA-MB-231 (human breast epithelial carcinoma cell lines) tumor cell lines inducing apoptotic type cell death, whereas normal fibroblasts were significantly less sensitive. The impact on cell cycle of these cells was distinctive, where Pd4, Pd5 and Pd6 showed the most prominent effect arresting MDA-MB-231 (human lung fibroblast cell lines) cell in G1/S phase of cell

Thermodynamics of axial substitution and kinetics of reactions with amino acids for the paddlewheel complex tetrakis(acetato)chloridodiruthenium(II,III).

Science.gov (United States)

Santos, Rodrigo L S R; van Eldik, Rudi; de Oliveira Silva, Denise

2012-06-18

The known paddlewheel, tetrakis(acetato)chloridodiruthenium(II,III), offers a versatile synthetic route to a novel class of antitumor diruthenium(II,III) metallo drugs, where the equatorial ligands are nonsteroidal anti-inflammatory carboxylates. This complex was studied here as a soluble starting prototype model for antitumor analogues to elucidate the reactivity of the [Ru(2)(CH(3)COO)(4)](+) framework. Thermodynamic studies on equilibration reactions for axial substitution of water by chloride and kinetic studies on reactions of the diaqua complexes with the amino acids glycine, cysteine, histidine, and tryptophan were performed. The standard thermodynamic reaction parameters ΔH°, ΔS°, and ΔV° were determined and showed that both of the sequential axial substitution reactions are enthalpy driven. Kinetic rate laws and rate constants were determined for the axial substitution reactions of coordinated water by the amino acids that gave the corresponding aqua(amino acid)-Ru(2) substituted species. The results revealed that the [Ru(2)(CH(3)COO)(4)](+) paddlewheel framework remained stable during the axial ligand substitution reactions and was also mostly preserved in the presence of the amino acids.

Homoleptic mono- and dinuclear cationic alkoxydiphosphazane derivatives of rhodium

International Nuclear Information System (INIS)

Edwards, K.J.; Haines, R.J.; Meintjies, E.; Sigwarth, B.

1990-01-01

Treatment of the solvento species [Rh(C 8 H 12 )(solvent) 2 ][SbF 6 ] (solvent = methanol, ethanol, or tetrahydrofuran) with a twice-molar amount of the diphosphazane ligands (RO) 2 PN(R') P(OR) 2 (R' = Me or Et; R = Me, Et, or Pr i ) in the appropriate solvent leads to the ready formation of monocationic [Rh{(RO) 2 PN(R')P(OR) 2 } 2 ] + and/or dicationic [Rh 2 {μ-(RO) 2 PN(R')P(OR) 2 } 2 {(RO) 2 PN(R')P(OR) 2 } 2 ] 2+ hexafluoroantimonate salts, with the tendency to afford dinuclear derivatives decreasing along the series Me>Et>Pr i . Carbon monoxide readily forms addition products with these ionic species, giving rise to five-coordinate derivatives of the type [Rh(CO){(RO) 2 PN(R')P (OR) 2 } 2 ][SbF 6 ] in the case of the mononuclear derivatives, and inserting across the two rhodium atoms to afford [Rh 2 (μ-CO){μ-(MeO) 2 PN(Et)P(OMe) 2 } 2 {(MeO) 2 PN(Et)P(OMe) 2 } 2 ][SbF 6 ] 2 in the case of [Rh 2 {μ-(MeO) 2 PN (Et)P(OMe) 2 } 2 {(MeO) 2 PN(Et)P(OMe) 2 } 2 ][SbF 6 ] 2 . These mono- and dicationic derivatives also react readily with iodine affording [RhI 2 {(RO) 2 PN(R')P(OR) 2 } 2 ][SbF 6 ] and [Rh 2 (μ-I){μ-(MeO) 2 PN(Et)P(OMe) 2 } 2 {(MeO) 2 PN(Et)P(OMe) 2 } 2 ][SbF 6 ] n (n = 2 or 3) respectively. The coordination behaviour of the diphosphorus ligands (MeO) 2 PCH 2 P(OMe) 2 and Me 2 PCH 2 PMe 2 towards [Rh(C 8 H 12 )(solvent) 2 ][SbF 6 ] has also been investigated. 1 fig., 1 tab., 19 refs

A new approach for crystallization of copper(ii) oxide hollow nanostructures with superior catalytic and magnetic response

Science.gov (United States)

Singh, Inderjeet; Landfester, Katharina; Chandra, Amreesh; Muñoz-Espí, Rafael

2015-11-01

We report the synthesis of copper(ii) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism.We report the synthesis of copper(ii) oxide hollow nanostructures at ambient pressure and close to room temperature by applying the soft templating effect provided by the confinement of droplets in miniemulsion systems. Particle growth can be explained by considering a mechanism that involves both diffusion and reaction control. The catalytic reduction of p-nitrophenol in aqueous media is used as a model reaction to prove the catalytic activity of the materials: the synthesized hollow structures show nearly 100 times higher rate constants than solid CuO microspheres. The kinetic behavior and the order of the reduction reaction change due to the increase of the surface area of the hollow structures. The synthesis also leads to modification of physical properties such as magnetism. Electronic supplementary information (ESI) available: Associated structural and morphological analysis, XPS characterization, BET surface area, catalytic measurements, recycle tests of the catalyst, and magnetic characterizations. See DOI: 10.1039/c5nr05579b

Electronic communication in phosphine substituted bridged dirhenium complexes - clarifying ambiguities raised by the redox non-innocence of the C4H2- and C4-bridges.

Science.gov (United States)

Li, Yan; Blacque, Olivier; Fox, Thomas; Luber, Sandra; Polit, Walther; Winter, Rainer F; Venkatesan, Koushik; Berke, Heinz

2016-04-07

The mononuclear rhenium carbyne complex trans-[Re(C[triple bond, length as m-dash]CSiMe3)([triple bond, length as m-dash]C-Me)(PMe3)4][PF6] (2) was prepared in 90% yield by heating a mixture of the dinitrogen complex trans-[ReCl(N2)(PMe3)4] (1), TlPF6, and an excess of HC[triple bond, length as m-dash]CSiMe3. 2 could be deprotonated with KOtBu to the vinylidene complex trans-[Re(C[triple bond, length as m-dash]CSiMe3)([double bond, length as m-dash]C[double bond, length as m-dash]CH2)(PMe3)4] (3) in 98% yield. Oxidation of 3 with 1.2 equiv. of [Cp2Fe][PF6] at -78 °C gave the Cβ-C'β coupled dinuclear rhenium biscarbyne complex trans-[(Me3SiC[triple bond, length as m-dash]C)(PMe3)4Re[triple bond, length as m-dash]C-CH2-CH2-C[triple bond, length as m-dash]Re(PMe3)4(C[triple bond, length as m-dash]CSiMe3)][PF6]2 (5) in 92% yield. Deprotonation of 5 with an excess of KOtBu in THF produced the diamagnetic trans-[(Me3SiC[triple bond, length as m-dash]C)(PMe3)4Re[double bond, length as m-dash]C[double bond, length as m-dash]CH-CH[double bond, length as m-dash]C[double bond, length as m-dash]Re(PMe3)4(C[triple bond, length as m-dash]CSiMe3)] complex (E-6(S)) in 87% yield with an E-butadienediylidene bridge. Density functional theory (DFT) calculations of E-6(S) confirmed its singlet ground state. The Z-form of 6 (Z-6(S)) could not be observed, which is in accord with its DFT calculated 17.8 kJ mol(-1) higher energy. Oxidation of E-6 with 2 equiv. of [Cp2Fe][PF6] resulted in the stable diamagnetic dicationic trans-[(Me3SiC[triple bond, length as m-dash]C)(PMe3)4Re[triple bond, length as m-dash]C-CH[double bond, length as m-dash]CH-C[triple bond, length as m-dash]Re(PMe3)4(C[triple bond, length as m-dash]CSiMe3)][PF6]2 complex (E-6[PF6]2) with an ethylenylidene dicarbyne structure of the bridge. The paramagnetic mixed-valence (MV) complex E-6[PF6] was obtained by comproportionation of E-6(S) and E-6[PF6]2 or by oxidation of E-6(S) with 1 equiv. of [Cp2Fe][PF6]. The

Synthesis and properties of ansa-titano- and ansa-zirconocenes

Energy Technology Data Exchange (ETDEWEB)

Churakov, A.V.; Nifant`ev, I.E. [M.V. Lomonosov Moscow State Univ. (Russian Federation); Urazovskii, I.F. [Institute of Chemical Physics, Chernogolovka (Russian Federation); Nikonov, G.I.; Yufit, D.S.; Struchkov, Yu.T. [A.N. Nesmeyanov Institute of Organoelement Compounds, Moscow (Russian Federation)

1993-11-01

A series of methyl and allyl derivatives of ansa-titano- and ansa-zirconocenes with isopropylidene or dimethylsilyl bridging groups were synthesized. A dinuclear complex, [Me{sub 2}C(C{sub 5}H{sub 4}){sub 2}]{sub 2}Ti{sub 2}P{sub 2}, resulting from the thermal decomposition of the corresponding dimethyl derivative of ansa-titanocene in the air, was characterized by X-ray diffraction analysis.

COMPOSITIONS BASED ON PALLADIUM(II AND COPPER(II COMPOUNDS, HALIDE IONS, AND BENTONITE FOR OZONE DECOMPOSITION

Directory of Open Access Journals (Sweden)

T. L. Rakitskaya

2017-05-01

bromide ion. For Cu(II-KBr/N-Bent composition, kinetic and calculation data show that, in the presence of bromide ions, copper(II inhibits the ozone decomposition. For Pd(II-KBr/NBent composition, it has been found that the maximum activity is attained at СPd(II = 1.02·10-5 mol/g. For bimetallic Pd(II- Cu(II-KBr/N-Bent composition, changes in τ0, τ1/2, k1/2, and Q1/2 parameters depending on a Pd(II content are similar to those for monometallic Pd(II-KBr/NBent composition; however, values of the parameters are higher for the monometallic system. Thus, the inhibiting effect of Cu(II is observed even in the presence of palladium(II.

Copper(II) oxide solubility behavior in aqueous sodium phosphate solutions at elevated temperatures

International Nuclear Information System (INIS)

Ziemniak, S.E.; Jones, M.E.; Combs, K.E.S.

1990-02-01

A platinum-lined, flowing autoclave facility is used to investigate the solubility behavior of copper(II) oxide (CuO) in aqueous sodium phosphate solutions at temperatures between 292 and 535 K. Copper solubilities are observed to increase continuously with temperature and phosphate concentration. The measured solubility is examined via a Cu(II) ion hydrolysis/complexing model and thermodynamic functions for the hydrolysis/complexing reactions are obtained from a least- squares analysis of the data. Altogether, thermochemical properties are established for five anionic complexes: Cu(OH) 3 - , Cu(OH) 4 = , Cu(OH) 2 (HPO 4 ) = , Cu(OH) 3 (H 2 PO 4 ) = , and Cu(OH) 2 (PO 4 ) ≡ . Precise thermochemical parameters are also derived for the Cu(OH) + hydroxocomplex based on CuO solubility behavior previously observed in pure water (*) at elevated temperatures. The relative ease of Cu(II) ion hydrolysis is such that Cu(OH) 3 - species become the preferred hydroxocomplex for pH ≥ 9.4. 20 refs., 8 figs., 6 tabs

Bridges

NARCIS (Netherlands)

Zant, W.

2017-01-01

We estimate to what extent bridges in Mozambique lead to transport cost reductions and attribute these reductions to key determinants, in particular road distance, road quality and crossing borders. For identification we exploit the introduction of a road bridge over the Zambezi river, in August

Field performance of timber bridges. 4, Graves Crossing stress-laminated deck bridge

Science.gov (United States)

J. P. Wacker; M. A. Ritter

The Graves Crossing bridge was constructed October 1991 in Antrim County, Michigan, as part of the demonstration timber bridge program sponsored by the USDA Forest Service. The bridge is a two-span continuous, stress-laminated deck superstructure and it is 36-ft long and 26-ft wide. The bridge is one of the first stress-laminated deck bridges to be built of sawn lumber...

Myocardial Bridging

Directory of Open Access Journals (Sweden)

Shi-Min Yuan

2016-02-01

Full Text Available Abstract Myocardial bridging is rare. Myocardial bridges are most commonly localized in the middle segment of the left anterior descending coronary artery. The anatomic features of the bridges vary significantly. Alterations of the endothelial morphology and the vasoactive agents impact on the progression of atherosclerosis of myocardial bridging. Patients may present with chest pain, myocardial infarction, arrhythmia and even sudden death. Patients who respond poorly to the medical treatment with β-blockers warrant a surgical intervention. Myotomy is a preferred surgical procedure for the symptomatic patients. Coronary stent deployment has been in limited use due to the unsatisfactory long-term results.

The hepatic bridge.

Science.gov (United States)

Sugarbaker, Paul H

2018-07-01

The hepatic bridge forms a tunnel of liver parenchyma that may obscure peritoneal metastases associated with the round ligament. Visualization and then resection of nodules associated with this structure is necessary. The incidence of a hepatic bridge and the extent that it covered the round ligament was determined in consecutive patients. Extent of coverage of the round ligament by the hepatic bridge was determined: Class 1 indicates up to one-third of the round ligament obscured, Class 2 up to two-thirds and Class 3 more than two-thirds. In 102 patients in whom the round ligament of the liver could be completely visualized, 50 had a hepatic bridge. Class 1 was 22 (44%) of the bridges, Class 2 was 16 (32%) and Class 3 was 12 (24%). A hepatic bridge was more frequently present in 28 of 45 male patients (62%) vs. 22 of 57 female patients (38%). Approximately one-half of our patients having cytoreductive surgery for peritoneal metastases were observed to have a hepatic bridge. Up to 56% of these patients have Class 2 or 3 hepatic bridge and may require division of the hepatic bridge to completely visualize the contents of the tunnel created by this structure. Copyright © 2018 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

Antimalarial, antimicrobial, cytotoxic, DNA interaction and SOD like activities of tetrahedral copper(II) complexes

Science.gov (United States)

Mehta, Jugal V.; Gajera, Sanjay B.; Patel, Mohan N.

2015-02-01

The mononuclear copper(II) complexes with P, O-donor ligand and different fluoroquinolones have been synthesized and characterized by elemental analysis, electronic spectra, TGA, EPR, FT-IR and LC-MS spectroscopy. An antimicrobial efficiency of the complexes has been tested against five different microorganisms in terms of minimum inhibitory concentration (MIC) and displays very good antimicrobial activity. The binding strength and binding mode of the complexes with Herring Sperm DNA (HS DNA) have been investigated by absorption titration and viscosity measurement studies. The studies suggest the classical intercalative mode of DNA binding. Gel electrophoresis assay determines the ability of the complexes to cleave the supercoiled form of pUC19 DNA. Synthesized complexes have been tested for their SOD mimic activity using nonenzymatic NBT/NADH/PMS system and found to have good antioxidant activity. All the complexes show good cytotoxic and in vitro antimalarial activities.

Bridge resource program.

Science.gov (United States)

2013-09-01

The mission of Rutgers Universitys Center for Advanced Infrastructure and Transportation (CAIT) Bridge Resource Program (BRP) is to provide bridge engineering support to the New Jersey Department of Transportation (NJDOT)s Bridge Engineering an...

Bridged graphite oxide materials

Science.gov (United States)

Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

2010-01-01

Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

Laboratory and field testing of an accelerated bridge construction demonstration bridge : US Highway 6 bridge over Keg Creek.

Science.gov (United States)

2013-04-01

The US Highway 6 Bridge over Keg Creek outside of Council Bluffs, Iowa is a demonstration bridge site chosen to put into practice : newly-developed Accelerated Bridge Construction (ABC) concepts. One of these new concepts is the use of prefabricated ...

Guardrails for Use on Historic Bridges: Volume 2—Bridge Deck Overhang Design

OpenAIRE

Frosch, Robert J.; Morel, Adam J.

2016-01-01

Bridges that are designated historic present a special challenge to bridge engineers whenever rehabilitation work or improvements are made to the bridges. Federal and state laws protect historically significant bridges, and railings on these bridges can be subject to protection because of the role they play in aesthetics. Unfortunately, original railings on historic bridges do not typically meet current crash-test requirements and typically do not meet current standards for railing height and...

Condensed, solution and gas phase behaviour of mono- and dinuclear 2,6-diacetylpyridine (dap) hydrazone copper complexes probed by X-ray, mass spectrometry and theoretical calculations.

Science.gov (United States)

Neto, Brenno A D; Viana, Barbara F L; Rodrigues, Thyago S; Lalli, Priscila M; Eberlin, Marcos N; da Silva, Wender A; de Oliveira, Heibbe C B; Gatto, Claudia C

2013-08-28

We describe the synthesis of novel mononuclear and dinuclear copper complexes and an investigation of their behaviour in solution using mass spectrometry (ESI-MS and ESI-MS/MS) and in the solid state using X-ray crystallography. The complexes were synthesized from two widely used diacetylpryridine (dap) ligands, i.e. 2,6-diacetylpyridinebis(benzoic acid hydrazone) and 2,6-diacetylpyridinebis(2-aminobenzoic acid hydrazone). Theoretical calculations (DFT) were used to predict the complex geometries of these new structures, their equilibrium in solution and energies associated with the transformations.

Dynamic assessment of bridge deck performance considering realistic bridge-traffic interaction

Science.gov (United States)

2017-09-01

Concrete bridge decks are directly exposed to daily traffic loads and may experience some surface cracking caused by excessive stress or fatigue accumulation, which requires repair or replacement. Among typical bridges in North America, bridge decks ...

Estudio de propiedades térmicas y mecánicas en espumas de mezclas poliméricas entre copolímero de etileno-acetato de vinilo (EAV y caucho natural (CN

Directory of Open Access Journals (Sweden)

Daniel Alberto Morales Rivera

2006-01-01

Full Text Available Se estudiaron algunas propiedades de espumas poliméricas, preparadas con mezclas de copolímeros de etileno-acetato de vinilo (EAV y caucho natural (CN: comportamiento térmico, por análisis térmico diferencial (DSC, y análisis termogravimétrico (TGA, resistencia a la tracción, compresión set y contenido de gel. Se establecieron relaciones entre la composición de las mezclas y las propiedades medidas en función de la reticulación y el espumado, teniendo en cuenta estudios previos realizados en espumas poliolefínicas con densidades similares.

Cable Supported Bridges

DEFF Research Database (Denmark)

Gimsing, Niels Jørgen

Cable supported bridges in the form of suspension bridges and cable-stayed bridges are distinguished by their ability to overcome large spans.The book concentrates on the synthesis of cable supported bridges, covering both design and construction aspects. The analytical part covers simple methods...... to quantify the different structural configurations and allows a preliminary optimization of the main structure.Included are the most recent advances in structural design, corrosion protection of cables, aerodynamic safety, and erection procedures....

Hydride Reactivity of Ni-II-X-Ni-II Entities : Mixed-Valent Hydrido Complexes and Reversible Metal Reduction

NARCIS (Netherlands)

Gehring, Henrike; Metzinger, Ramona; Herwig, Christian; Intemann, Julia; Harder, Sjoerd; Limberg, Christian

After the lithiation of PYR-H2 (PYR2-=[{NC(Me)C(H)C(Me)NC6H3(iPr)2}2(C5H3N)]2-), which is the precursor of an expanded beta-diketiminato ligand system with two binding pockets, its reaction with [NiBr2(dme)] led to a dinuclear nickel(II)bromide complex, [(PYR)Ni(mu-Br)NiBr] (1). The bridging bromide

Facile synthesis of gold coated copper(II) hydroxide pine-needle-like micro/nanostructures for surface-enhanced Raman scattering

Science.gov (United States)

Long, Kailin; Du, Deyang; Luo, Xiaoguang; Zhao, Weiwei; Wu, Zhangting; Si, Lifang; Qiu, Teng

2014-08-01

This work reports a facile method to fabricate gold coated copper(II) hydroxide pine-needle-like micro/nanostructures for surface-enhanced Raman scattering (SERS) application. The effects of reaction parameters on the shape, size and surface morphology of the products are systematically investigated. The as-prepared 3D hierarchical structures have the advantage of a large surface area available for the formation of hot spots and the adsorption of target analytes, thus dramatically improving the Raman signals. The finite difference time domain calculations indicate that the pine-needle-like model pattern may demonstrate a high quality SERS property owing to the high density and abundant hot spot characteristic in closely spaced needle-like arms.

A dinuclear copper complex: bis(μ-4-aminobenzoatobis[aqua(1,10-phenanthrolinecopper(II] dichloride bis(4-aminobenzoic acid dihydrate

Directory of Open Access Journals (Sweden)

Miao-Ling Huang

2008-08-01

Full Text Available The title complex, [Cu2(C7H6NO22(C12H8N22(H2O2]·2C7H7NO2·2H2O, consists of a dinuclear [Cu2(C7H6NO22(C12H8N22(H2O2]2+ cation, two Cl− anions, two 4-aminobenzoic acid molecules and two disordered water molecules (site occupancy factors 0.5. The Cu(II ion adopts a distorted square-pyramidal geometry formed by two N atoms from the 1,10-phenanthroline ligand and two O atoms of the two 4-aminobenzoic acid ligands and one water O atom. The Cu...Cu separation is 3.109 (2 Å. A twofold axis passes through the mid-point of the Cu...Cu vector.

Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

Science.gov (United States)

Chumakov, Yu. M.; Tsapkov, V. I.; Jeanneau, E.; Bairac, N. N.; Bocelli, G.; Poirier, D.; Roy, J.; Gulea, A. P.

2008-09-01

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate ( I), bromo-(2-formylpyridinethiosemicarbazono)copper ( II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate ( III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I III at a concentration of 10-5 mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

International Nuclear Information System (INIS)

Chumakov, Yu. M.; Tsapkov, V. I.; Jeanneau, E.; Bairac, N. N.; Bocelli, G.; Poirier, D.; Roy, J.; Gulea, A. P.

2008-01-01

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate (I), bromo-(2-formylpyridinethiosemicarbazono)copper (II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate (III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I-III at a concentration of 10 -5 mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

Crystal structures of copper(II) chloride, copper(II) bromide, and copper(II) nitrate complexes with pyridine-2-carbaldehyde thiosemicarbazone

Energy Technology Data Exchange (ETDEWEB)

Chumakov, Yu. M., E-mail: chumakov.xray@phys.asm.md [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of); Tsapkov, V. I. [State University of Moldova (Moldova, Republic of); Jeanneau, E. [Universite Claude Bernard, Laboratoire des Multimateriaux et Interfaces (France); Bairac, N. N. [State University of Moldova (Moldova, Republic of); Bocelli, G. [National Research Council (IMEM-CNR), Institute of Materials for Electronics and Magnetism (Italy); Poirier, D.; Roy, J. [Centre Hospitalier Universitaire de Quebec (CHUQ) (Canada); Gulea, A. P. [State University of Moldova (Moldova, Republic of)

2008-09-15

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate (I), bromo-(2-formylpyridinethiosemicarbazono)copper (II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate (III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I-III at a concentration of 10{sup -5} mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

SYNTHESIS, CRYSTAL STRUCTURE AND LUMINESCENT PROPERTY OF A DINUCLEAR Tb(II COMPLEX WITH HOMOPHTHALIC ACID AND 2,2’-BIPYRIDYL

Directory of Open Access Journals (Sweden)

LI-HUA WANG

2015-07-01

Full Text Available A novel dinuclear Tb(III complex, [Tb(bpy2L2] (bpy = 2,2’-bipyridine, H2L = homophthalic acid, has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. The Tb(III complex is monoclinic, space group P21/c with a = 9.368(2 Å, b = 15.948(4 Å, c = 12.216(3 Å, β = 103.023(4º, V= 1778.2(7 Å3, Z = 2, Dc = 1.910 mg·m-3, μ = 4.011 mm-1, F(000 = 996, and final R1 = 0.0602, ωR2 = 0.2192. The result shows that the Tb(III center is seven-coordination with a N2O5 distorted pengonal bipyramidal geometry. The luminescent property of Tb(III complex was investigated.

Bridge Programs in Illinois: Results of the 2010 Illinois Bridge Status Survey

Science.gov (United States)

Taylor, J. L.; Harmon, T.

2010-01-01

This report provides a summary of major results of the Illinois Bridge Status Survey, administered online between April and June 2010. The purpose of the survey was to understand the extent to which bridge programs are being implemented in Illinois, as well as to build an online directory of bridge programs. Bridge programs are an emerging…

Field performance of timber bridges. 6, Hoffman Run stress-laminated deck bridge

Science.gov (United States)

M. A. Ritter; P. D. Hilbrich Lee; G. J. Porter

The Hoffman Run bridge, located just outside Dahoga, Pennsylvania, was constructed in October 1990. The bridge is a simple-span, single-lane, stress-laminated deck superstructure that is approximately 26 ft long and 16 ft wide. It is the second stress-laminated timber bridge to be constructed of hardwood lumber in Pennsylvania. The performance of the bridge was...

Drill pipe bridge plug

International Nuclear Information System (INIS)

Winslow, D.W.; Brisco, D.P.

1991-01-01

This patent describes a method of stopping flow of fluid up through a pipe bore of a pipe string in a well. It comprises: lowering a bridge plug apparatus on a work string into the pipe string to a position where the pipe bore is to be closed; communicating the pipe bore below a packer of the bridge plug apparatus through the bridge plug apparatus with a low pressure zone above the packer to permit the fluid to flow up through the bridge plug apparatus; engaging the bridge plug apparatus with an internal upset of the pipe string; while the fluid is flowing up through the bridge plug apparatus, pulling upward on the work string and the bridge plug apparatus and thereby sealing the packer against the pipe bore; isolating the pipe bore below the packer from the low pressure zone above the packer and thereby stopping flow of the fluid up through the pipe bore; disconnecting the work string from the bridge plug apparatus; and maintaining the bridge plug apparatus in engagement with the internal upset and sealed against the pipe bore due to an upward pressure differential applied to the bridge plug apparatus by the fluid contained therebelow

Two luminescent frameworks constructed from lead(II) salts with carboxylate ligands containing dinuclear lead(II) units

International Nuclear Information System (INIS)

Zhu Xiandong; Li Xiaoju; Liu Qingyan; Lue Jian; Guo Zhengang; He Jinrun; Li Yafeng; Cao Rong

2007-01-01

Two luminescent Pb(II) coordination frameworks containing dinuclear lead(II) units, [Pb(PYDC)(H 2 O)] n (1) and [Pb(HPHT)] n (2) have been prepared by the self-assembly of lead(II) salts with pyridinecarboxylate and benzenecarboxylate. Single-crystal X-ray diffraction analyses reveal that compound 1 is a three-dimensional architecture consisting of Pb 2 O 2 dimeric building units, whereas compound 2 is a two-dimensional layer structure containing one-dimensional lead-oxide chains. The luminescent properties of 1 and 2 have been investigated in the solid state at room temperature, indicating structure-dependent photoluminescent properties of the coordination frameworks. - Graphical abstract: Two luminescent Pb(II) coordination frameworks, [Pb(PYDC)(H 2 O)] n (1) and [Pb(HPHT)] n (2) have been prepared. Single-crystal analyses reveal that compound 1 is a three-dimensional architecture consisting of Pb 2 O 2 dimeric building units, whereas compound 2 is a two-dimensional layer structure containing one-dimensional lead-oxide chains. The luminescent properties have been investigated, indicating structure-dependent photoluminescent properties of the coordination frameworks

MEDICIÓN Y MODELADO: DENSIDAD, VELOCIDAD DEL SONIDO Y VISCOSIDAD DEL SISTEMA BINARIO TOLUENO + ACETATO DE METILO A DISTINTAS TEMPERATURAS

Directory of Open Access Journals (Sweden)

Alberto Camacho

2012-01-01

Full Text Available Se estudió el efecto de la temperatura sobre el volumen molar, la velocidad del sonido, la viscosidad y las propiedades derivadas para el sistema binario tolueno + acetato de metilo a 15, 20, 25, 30, 35, 40, y 45 oC y a presión atmosférica. De las propiedades medidas se calculó, el volumen molar de exceso, la desviación de la velocidad del sonido, la desviación de la viscosidad y el exceso de energía de activación por flujo viscoso. El volumen molar de exceso y la desviación de la velocidad del sonido presentaron valores positivos, mientras que la desviación de la viscosidad resultó negativa. Se aplicaron ecuaciones empíricas a las propiedades derivadas para determinar sus parámetros de ajuste, obteniéndose buenos resultados. Se realizó la predicción de la velocidad del sonido con modelos disponibles en la literatura y la predicción de la viscosidad con modelos de contribución de grupos; en ambos casos los resultados obtenidos fueron aceptables.

Bridging Anticoagulation

Science.gov (United States)

... clinical centers in the United States, Canada, and Brazil. A more detailed description of the study is ... Your Personal Message Send Message Share on Social Media Bridging Anticoagulation The BRIDGE Study Investigators Circulation. 2012; ...

Nonlinear optical and G-Quadruplex DNA stabilization properties of novel mixed ligand copper(II) complexes and coordination polymers: Synthesis, structural characterization and computational studies

Science.gov (United States)

Rajasekhar, Bathula; Bodavarapu, Navya; Sridevi, M.; Thamizhselvi, G.; RizhaNazar, K.; Padmanaban, R.; Swu, Toka

2018-03-01

The present study reports the synthesis and evaluation of nonlinear optical property and G-Quadruplex DNA Stabilization of five novel copper(II) mixed ligand complexes. They were synthesized from copper(II) salt, 2,5- and 2,3- pyridinedicarboxylic acid, diethylenetriamine and amide based ligand (AL). The crystal structure of these complexes were determined through X-ray diffraction and supported by ESI-MAS, NMR, UV-Vis and FT-IR spectroscopic methods. Their nonlinear optical property was studied using Gaussian09 computer program. For structural optimization and nonlinear optical property, density functional theory (DFT) based B3LYP method was used with LANL2DZ basis set for metal ion and 6-31G∗ for C,H,N,O and Cl atoms. The present work reveals that pre-polarized Complex-2 showed higher β value (29.59 × 10-30e.s.u) as compared to that of neutral complex-1 (β = 0.276 × 10-30e.s.u.) which may be due to greater advantage of polarizability. Complex-2 is expected to be a potential material for optoelectronic and photonic technologies. Docking studies using AutodockVina revealed that complex-2 has higher binding energy for both G-Quadruplex DNA (-8.7 kcal/mol) and duplex DNA (-10.1 kcal/mol). It was also observed that structure plays an important role in binding efficiency.

Bridging the Gap

DEFF Research Database (Denmark)

Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska

Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

Long Span Bridges in Scandinavia

DEFF Research Database (Denmark)

Gimsing, Niels Jørgen

1998-01-01

The first Scandinavian bridge with a span of more than 500 m was the Lillebælt Suspension Bridge opened to traffic in 1970.Art the end of the 20th century the longest span of any European bridge is found in the Storebælt East Bridge with a main span of 1624 m. Also the third longest span in Europe...... is found in Scandinavia - the 1210 m span of the Höga Kusten Bridge in Sweden.The Kvarnsund Bridge in Norway was at the completion in 1991 the longest cable-stayed bridge in the world, and the span of 530 m is still thge longest for cable-stayed bridges in concrete. The Øresund Bridge with its sapn of 490...

Determination of catechin in green tea using a catechol oxidase biomimetic sensor

International Nuclear Information System (INIS)

Fernandes, Suellen C.; Osorio, Renata El-Hage M. de Barros; Anjos, Ademir dos; Neves, Ademir; Micke, Gustavo Amadeu; Vieira, Iolanda C.

2008-01-01

A catechol oxidase biomimetic sensor, based on a novel copper(II) complex, was developed for the determination of catechin in green tea and the results were compared with those obtained by capillary electrophoresis. The dinuclear copper(II) complex, [Cu 2 (HL)(μ-CH 3 COO)](ClO 4 ), containing the ligand N,N-[bis-(2-pyridylmethyl)]-N',N'-[(2-hydroxybenzyl)(2-hydroxy-3,5-di-tert - butylbenzyl)]-1,3-propanediamine-2-ol (H 3 L), was synthesized and characterized by IR, 1 H NMR and elemental analysis. The best conditions for the optimization of the biomimetic sensor were established by square wave voltammetry. The best performance for this sensor was obtained in 75:15:10% (m/m/m) of the graphite powder:nujol:copper(II) complex, 0.05 mol L -1 phosphate buffer solution (pH 7.5) and frequency, pulse amplitude, scan increment at 30 Hz, 80 mV, 3.3 mV, respectively. The analytical curve was linear in the concentration range 4.95 x 10 -6 to 3.27 x 10 -5 mol L -1 (r = 0.9993) with a detection limit of 2.8 x 10 -7 mol L -1 . This biomimetic sensor demonstrated long-term stability (9 months; 800 determinations) and reproducibility with a relative standard deviation of 3.5%. The recovery of catechin from green tea samples ranged from 93.8 to 106.9% and the determination, compared with that obtained using capillary electrophoresis, was found to be acceptable at the 95% confidence level. (author)

Acetato de celulosa del bagazo de la caña de azúcar: plastificación y evaluación de propiedades

Directory of Open Access Journals (Sweden)

Angel Tomás Pérez - Rodríguez

2013-01-01

Full Text Available En el trabajo se realizó la plastificación del acetato de celulosa (AC obtenido a partir del bagazo de la caña de azúcar. Se utilizaron como plastificantes el dietilftalato (DEF y el trifenilfosfato (TFP en diferentes proporciones, empleando acetona para mejorar el mezclado. A partir de un diseño experimental factorial 2 3 , se evalu aron los posibles efectos que provocan las variaciones de la composición en las propiedades físicas y mecánicas del plástico obtenido. Los ensayos se realizaron con películas obtenidas por prensado en caliente, preparando las probetas por troquelado. Se ob servaron efectos estadísticamente significativos para la tensión máxima, el alargamiento a la rotura, la absorción de agua, la dureza Rockwell y la temperatura de ablandamiento Vicat. Los resultados obtenidos demuestran que es posible la plastificación del AC obtenido a partir de la celulosa de bajo grado de polimerización.

Acetato de celulosa del bagazo de la caña de azúcar: plastificación y evaluación de propiedades

Directory of Open Access Journals (Sweden)

Ángel Tomás Pérez-Rodríguez

2014-01-01

Full Text Available En el trabajo se realizó la plastificación del acetato de celulosa (AC obtenido a partir del bagazo de la caña de azúcar. Se utilizaron como plastificantes el dietilftalato (DEF y el trifenilfosfato (TFP en diferentes proporciones, empleando acetona para mejorar el mezclado. A partir de un diseño experimental factorial 23, se evaluaron los posibles efectos que provocan las variaciones de la composición en las propiedades físicas y mecánicas del plástico obtenido. Los ensayos se realizaron con películas obtenidas por prensado en caliente, preparando las probetas por troquelado. Se observaron efectos estadísticamente significativos para la tensión máxima, el alargamiento a la rotura, la absorción de agua, la dureza Rockwell y la temperatura de ablandamiento Vicat. Los resultados obtenidos demuestran que es posible la plastificación del AC obtenido a partir de la celulosa de bajo grado de polimerización.

Crystal structures of two erbium(III complexes with 4-aminobenzoic acid and 4-chloro-3-nitrobenzoic acid

Directory of Open Access Journals (Sweden)

Graham Smith

2015-12-01

Full Text Available The crystal structures of two erbium(III complexes with 4-aminobenzoic acid (4-ABAH, namely bis(μ2-4-aminobenzoato-κ2O:O′bis[bis(4-aminobenzoato-κ2O,O′diaquaerbium(III] dihydrate, [Er2(C7H6NO26(H2O4]·2H2O, (I, and 4-chloro-3-nitrobenzoic acid (CLNBAH, namely poly[hexakis(μ2-4-chloro-3-nitrobenzoato-κ2O:O′bis(dimethyl sulfoxide-κOdierbium(III], [Er2(C7H3ClNO46(C2H6OS2]n, (II, have been determined. In the structure of solvatomorphic compound (I, the symmetry-related irregular ErO8 coordination polyhedra in the discrete centrosymmetric dinuclear complex comprise two monodentate water molecules and six carboxylate O-atom donors, four from two bidentate carboxylate O,O′-chelate groups and two from the bis-monodentate O:O′-bridging group of the third 4-ABA anion. The Er—O bond-length range is 2.232 (3–2.478 (3 Å and the Er...Er separation in the dinuclear complex unit is 4.7527 (4 Å. One of the coordinating water molecules is involved in an intra-unit O—H...O hydrogen-bonding association with an inversion-related carboxylate O-atom acceptor. In contrast, the anhydrous compound (II is polymeric, based on centrosymmetric dinuclear repeat units comprising ErO7 coordination polyhedra which involve four O-atom donors from two bidentate O:O′-bridging carboxylate groups, one O-atom donor from the monodentate dimethyl sulfoxide ligand and two O-atom donors from the third bridging CLNBA anion. The latter provides the inter-unit link in the one-dimensional coordination polymer extending along [100]. The Er—O bond-length range in (II is 2.239 (6–2.348 (6 Å and the Er...Er separation within the dinuclear unit is 4.4620 (6 Å. In the crystal of (I, extensive inter-dimer O—H...O and N—H...O hydrogen-bonding interactions involving both the coordinating water molecules and the solvent water molecules, as well as the amine groups of the 4-ABA anions, give an overall three-dimensional network structure. Within

Integral Abutment and Jointless Bridges

Directory of Open Access Journals (Sweden)

Cristian-Claudiu Comisu

2005-01-01

Full Text Available Integral bridges, or integral abutment and jointless bridges, as they are more commonly known in the USA, are constructed without any movement joints between spans or between spans and abutments. Typically these bridges have stub-type abutments supported on piles and continuous bridge deck from one embankment to the other. Foundations are usually designed to be small and flexible to facilitate horizontal movement or rocking of the support. Integrally bridges are simple or multiple span ones that have their superstructure cast integrally with their substructure. The jointless bridges cost less to construct and require less maintenance then equivalent bridges with expansion joints. Integral bridges present a challenge for load distribution calculations because the bridge deck, piers, abutments, embankments and soil must all be considered as single compliant system. This paper presents some of the important features of integral abutment and jointless bridge design and some guidelines to achieve improved design. The goal of this paper is to enhance the awareness among the engineering community to use integral abutment and jointless bridges in Romania.

Bridge deterioration models to support Indiana's bridge management system.

Science.gov (United States)

2016-02-01

An effective bridge management system that is equipped with reliable deterioration models enables agency engineers to carry out : monitoring and long-term programming of bridge repair actions. At the project level, deterioration models help the agenc...

Automatic Bridge Control System

OpenAIRE

M. Niraimathi; S.Sivakumar; R.Vigneshwaran; R.Vinothkumar; P.Babu

2012-01-01

Bridge vibration control is an important issue whose purpose is to extend the structural service life of bridges. Normally, the bridge is modeled as an elastic beam or plate subject to a moving vehicle. However, the moving truck on a bridge is a complicated problem that must still be researched. In this paper, wepropose a new method, to overcome the huge load in the bridge a load cell is used at the entry which will monitor the load continuously at both ends. To escape from the heavy water fl...

Synthesis, physico-chemical characterization and biological activity of copper(ii and nickel(ii complexes with l-benzoyl-2-methylbenzimidazole derivatives

Directory of Open Access Journals (Sweden)

Podunavac-Kuzmanović Sanja O.

2002-01-01

Full Text Available Chlorides of copper(II and nickel(ll react with 1-benzoyl-2-methylbenzimidazole or 1-(4-chlorobenzoyl-2-methylbenzimidazole to give complexes of the type [M(LnCln(H20∙Cln (M = Cu or Ni; L = (1-benzoyl-2-methylbenzimidazole or 1-(4-chlorobenzoyl-2-methylbenzimidazole; n=O, 1 or 2. The complexes were synthesized and characterized by elemental analysis, molar conductivity magnetic susceptibility measurements and IR spectra. These studies suggest that all the complexes possess an octahedral stereochemistry. The antibacterial activity of (1-benzoyl-2-methylbenzimidazole or 1-(4-chlorobenzoyl-2-methylbenzimidazole and their complexes was evaluated against Escherichia coli and Bacillus sp.

[μ-N,N′-Bis(2-aminoethylethane-1,2-diamine-κ4N1,N1′:N2,N2′]bis{[N,N′-bis(2-aminoethylethane-1,2-diamine-κ4N,N′,N′′,N′′′]cadmium} tetrakis(perchlorate

Directory of Open Access Journals (Sweden)

Hamid Goudarziafshar

2012-09-01

Full Text Available The centrosymmetric dinuclear cadmium title complex, [Cd2(C6H18N43](ClO44, was obtained by the reaction of N,N′-bis(2-aminoethylethane-1,2-diamine (trien with Cd(NO32·4H2O and sodium perchlorate in methanol. The CdII cation is coordinated by four N atoms of a non-bridging trien ligand and by two N atoms of a bridging trien ligand in a slightly distorted octahedral coordination geometry. The bridging ligand shares another two N atoms with a neighboring symmetry-equivalent CdII cation. The structure displays C—H...O and N—H...O hydrogen bonding. The perchlorate anion is disordered over two sets of sites in a 0.854 (7: 0.146 (7 ratio.

Kinetics of the oxidative hydroxylation of tetraphosphorus in the presence of copper(II chloride modified by humic (fulvo- acid

Directory of Open Access Journals (Sweden)

Zhaksyntay Kairbekov

2012-12-01

Full Text Available It was established that in mild conditions (50-70 oC, РО2= 1 atm white phosphorus effectively is oxidized by oxygen in water-toluene solutions of copper(II chloride modified by humic (fulvo- acid to give mainly phosphoric acid. Humic (fulvo- acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, intermediate and final products, optimum conditions of new catalytic reaction of P4 oxidation by oxygen in water medium were defined by kinetics, volumometry, redox-potentiometry, 31Р{1Н} NMR spectroscopy and  titration. 

Di-μ-chlorido-bis[bis(η2-cycloocteneiridium(I

Directory of Open Access Journals (Sweden)

Kazuhide Tani

2008-04-01

Full Text Available The title complex, [Ir2(μ-Cl2(C8H144], has a dinuclear structure with bridging Cl atoms, a hinge angle of 179.44 (7° between the two IrCl2 planes, and an Ir...Ir distance of 3.7254 (3 Å. Regarding the coordinating C=C bonds as occupying a single coordination site each, the geometry around each Ir atom is square-planar.

Existing Steel Railway Bridges Evaluation

Science.gov (United States)

Vičan, Josef; Gocál, Jozef; Odrobiňák, Jaroslav; Koteš, Peter

2016-12-01

The article describes general principles and basis of evaluation of existing railway bridges based on the concept of load-carrying capacity determination. Compared to the design of a new bridge, the modified reliability level for existing bridges evaluation should be considered due to implementation of the additional data related to bridge condition and behaviour obtained from regular inspections. Based on those data respecting the bridge remaining lifetime, a modification of partial safety factors for actions and materials could be respected in the bridge evaluation process. A great attention is also paid to the specific problems of determination of load-caring capacity of steel railway bridges in service. Recommendation for global analysis and methodology for existing steel bridge superstructure load-carrying capacity determination are described too.

Field performance of timber bridges. 5, Little Salmon Creek stress-laminated deck bridge

Science.gov (United States)

M. A. Ritter; J. A. Kainz; G. J. Porter

The Little Salmon Creek bridge was constructed in November 1988 on the Allegheny National Forest in Pennsylvania. The bridge is a simple span, single-lane, stress-laminated deck superstructure that is approximately 26-ft long and 16-ft wide. The bridge is unique in that it is the first known stress-laminated timber bridge to be constructed of hardwood lumber. The...

Field performance of timber bridges. 9, Big Erick`s stress-laminated deck bridge

Science.gov (United States)

J. A. Kainz; J. P. Wacker; M. Nelson

The Big Erickas bridge was constructed during September 1992 in Baraga County, Michigan. The bridge is 72 ft long, 16 ft wide, and consists of three simple spans: two stress-laminated deck approach spans and a stress-laminated box center span. The bridge is unique in that it is one of the first known stress-laminated timber bridge applications to use Eastern Hemlock...

Hydraulic modeling of flow impact on bridge structures: a case study on Citarum bridge

Science.gov (United States)

Siregar, R. I.

2018-02-01

Flood waves because of the rapid catchment response to high intense rainfall, breaches of flood defenses may induce huge impact forces on structures, causing structural damage or even failures. Overflowing stream that passes over the bridge, it means to discharge flood water level is smaller than the capacity of the river flow. In this study, the researches present the methodological approach of flood modeling on bridge structures. The amount of force that obtained because of the hydrostatic pressure received by the bridge at the time of the flood caused the bridge structure disrupted. This paper presents simulation of flow impact on bridge structures with some event flood conditions. Estimating the hydrostatic pressure developed new model components, to quantify the flow impact on structures. Flow parameters applied the model for analyzing, such as discharge, velocity, and water level or head that effect of bridge structures. The simulation will illustrate the capability of bridge structures with some event flood river and observe the behavior of the flow that occurred during the flood. Hydraulic flood modeling use HEC-RAS for simulation. This modeling will describe the impact on bridge structures. Based on the above modelling resulted, in 2008 has flood effect more than other years on the Citarum Bridge, because its flow overflow on the bridge.

Existing Steel Railway Bridges Evaluation

Directory of Open Access Journals (Sweden)

Vičan Josef

2016-12-01

Full Text Available The article describes general principles and basis of evaluation of existing railway bridges based on the concept of load-carrying capacity determination. Compared to the design of a new bridge, the modified reliability level for existing bridges evaluation should be considered due to implementation of the additional data related to bridge condition and behaviour obtained from regular inspections. Based on those data respecting the bridge remaining lifetime, a modification of partial safety factors for actions and materials could be respected in the bridge evaluation process. A great attention is also paid to the specific problems of determination of load-caring capacity of steel railway bridges in service. Recommendation for global analysis and methodology for existing steel bridge superstructure load-carrying capacity determination are described too.

Light-weight aluminium bridges and bridge decks. An overview of recent applications

NARCIS (Netherlands)

Maljaars, J.; Soetens, F.; Kluyver, D. de

2008-01-01

The last decades have shown a large increase in the application of aluminium alloys for light-weight bridges. For bridge construction, aluminium alloys have some specific advantages, but also some points of attention. This paper deals with some recent projects of aluminium bridges, and for these

Development of bridge girder movement criteria for accelerated bridge construction.

Science.gov (United States)

2014-06-01

End diaphragms connect multiple girders to form a bridge superstructure system for effective resistance to earthquake loads. Concrete : girder bridges that include end diaphragms consistently proved to perform well during previous earthquake events. ...

Synthesis, thermogravimetric, spectroscopic and theoretical characterization of copper(II) complex with 4-chloro-2-nitrobenzenosulfonamide

Science.gov (United States)

Camí, G.; Chacón Villalba, E.; Di Santi, Y.; Colinas, P.; Estiu, G.; Soria, D. B.

2011-05-01

4-Chloro-2-nitrobenzenesulfonamide (ClNbsa) was purified and characterized. A new copper(II) complex, [Cu(ClNbsa) 2(NH 3) 2], has been prepared using the sulfonamide as ligand. The thermal behavior of both, the ligand and the Cu(II) complex, was investigated by thermogravimetric analyses (TG) and differential thermal analysis (DT), and the electronic characteristics analyzed by UV-VIS, FTIR, Raman and 1H NMR spectroscopies. The experimental IR, Raman and UV-VIS spectra have been assigned on the basis of DFT calculations at the B3LYP level of theory using the standard (6-31 + G ∗∗) basis set. The geometries have been fully optimized in vacuum and in modeled dimethylsulfoxide (DMSO) solvent, using for the latter a continuum solvation model that reproduced the experimental conditions of the UV-VIS spectroscopy. The theoretical results converged to stable conformations for the free sulfonamide and for the complex, suggesting for the latter a distorted square planar geometry in both environments.

Líquido dializante con citrato frente a acetato en pacientes en hemodiafiltración on-line de alta eficacia: parámetros a estudio

Directory of Open Access Journals (Sweden)

Sonia Aznar Barbero

2014-09-01

Full Text Available Introducción: El líquido dializante con acetato se reporta menos biocompatible, generando estrés oxidativo e inflamación. Entre los beneficios asociados al citrato destacan sus propiedades antiinflamatorias y antioxidantes, poder anticoagulante, quelante del calcio iónico, efecto tampón y mejora la tolerancia a la sesión. Objetivo: Comparar parámetros nutricionales e inflamatorios, eficacia dialítica, estatus ácido-base, tolerancia y balance de calcio en hemodiafiltración en línea empleando líquido dializante con citrato frente a líquido dializante con acetato. Material y métodos: Estudio prospectivo cruzado sobre población en hemodiafiltración en línea de 24 semanas. Inician 35 pacientes (finalizan 33, con 57,4 años, 55% hombres, 54,1 meses de permanencia. 79% portadores de fistula arteriovenosa. Se analizan 2376 sesiones. El estudio tiene dos fases. Variables: albúmina, PCR, Beta 2 microglobulinas (B2MCG, ángulo de fase (AF, masa celular corporal (BCM, Kt, volumen de reinfusión, PTTA, tiempo de hemostasia, estado de cámaras y dializador, pH, bicarbonato, calcio iónico, sesiones con hipotensión y calambres. Análisis estadístico SPSS 13.0. Contraste de hipótesis mediante T-Student y W de Wilcoxon para variables cuantitativas. Chi-cuadrado cualitativas. Significación estadística p<0,05. Resultados: Diferencias significativas (p<0,001 en albúmina, PCR, y B2MCG. BCM (p=0,001, AF (p=0,002 y Kt (p< 0,001 mayores con líquido de diálisis con citrato. Bicarbonato postdiálisis menor (p<0,001 con líquido de diálisis con citrato. Calcio iónico pre y postdiálisis (p=0,007 y p<0,001 respectivamente menores con líquido de diálisis con citrato. Conclusiones: La diálisis con citrato se muestra en nuestra serie más biocompatible y con menor inflamación, mejora los parámetros nutricionales analíticos y por impedancia e incrementa la eficacia dialítica. Reduce el bicarbonato postdiálisis. Tanto pre como postdi

Active Control of Suspension Bridges

DEFF Research Database (Denmark)

Thoft-Christensen, Palle

In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

Morphological aspects of myocardial bridges.

Science.gov (United States)

Lujinović, Almira; Kulenović, Amela; Kapur, Eldan; Gojak, Refet

2013-11-01

Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the "tunnel" segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64 ± 9.03 mm and the mean thickness was 1.23 ± 1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel.

Synthesis, molecular docking and DNA binding studies of phthalimide-based copper(II) complex: In vitro antibacterial, hemolytic and antioxidant assessment

Science.gov (United States)

Arif, Rizwan; Nayab, Pattan Sirajuddin; Ansari, Istikhar A.; Shahid, M.; Irfan, Mohammad; Alam, Shadab; Abid, Mohammad; Rahisuddin

2018-05-01

In the present research work, we prepared N-substituted phthalimide, 2-(-(2-(2-(2-(1,3-dioxoisoindoline-2-yl-ethylamino)ethylamino)ethyl)isoindoline-1,3-dione (DEEI) and its copper(II) complex. The ligand (DEEI) and its Cu(II) complex were structurally identified using absorption, FTIR, NMR, electron spin resonance, X-ray diffraction spectral studies, thermogravimetric and elemental analyses. The electronic spectrum and magnetic moment value proposed that Cu(II) complex has square planar geometry. The DNA interaction ability of the ligand (DEEI) and Cu(II) complex was studied by means of absorption and fluorescence spectrophotometer, viscosity measurements, cyclic voltammetery, and circular dichroism methods. The extent of DNA binding (Kb) with Calf thymus (Ct-DNA) follows the order of Cu(II) complex (1.11 × 106 M-1) > DEEI (1.0 × 105 M-1), indicating that Cu(II) complex interact with Ct-DNA through groove binding mode and more sturdily than ligand (DEEI). Interestingly, in silico predictions were corroborated with in vitro DNA binding studies. The antibacterial evaluation of these compounds was screened against a panel of bacterial strains Pseudomonas aeruginosa (MTCC 2453), Salmonella enterica (MTCC 3224), Streptococcus pneumoniae (MTCC 655), Enterococcus faecalis (MTCC 439), Klebsiella pneumonia and Escherichia coli (ATCC 25922). The results showed that the copper(II) complex has significant antibacterial potential (IC50 = 0.0019 μg/mL) against Salmonella enteric comparable with ligand (DEEI) and standard drug ciprofloxacin. Growth curve study of Cu(II) complex against only three bacterial strains S. enterica, E. faecalis and S. pneumoniae showed its bactericidal nature. Cu(II) complex showed less than 2% hemolysis on human RBCs indicating its non toxic nature. The results of antioxidant assay demonstrated that scavenging activity of Cu(II) complex is higher as compared to ligand and ascorbic acid as standard.

Field performance of timber bridges. 17, Ciphers stress-laminated deck bridge

Science.gov (United States)

James P. Wacker; James A. Kainz; Michael A. Ritter

In September 1989, the Ciphers bridge was constructed within the Beltrami Island State Forest in Roseau County, Minnesota. The bridge superstructure is a two-span continuous stress-laminated deck that is approximately 12.19 m long, 5.49 m wide, and 305 mm deep (40 ft long, 18 ft wide, and 12 in. deep). The bridge is one of the first to utilize red pine sawn lumber for...

Efeito do extrato acetato de etila de Trichilia pallida Swartz (Meliaceae no desenvolvimento e sobrevivência da lagarta-do-cartucho

Directory of Open Access Journals (Sweden)

ROEL ANTONIA RAILDA

2000-01-01

Full Text Available O efeito de diferentes concentrações (massa/volume do extrato acetato de etila de folhas e ramos de Trichilia pallida, em relação à lagarta-do-cartucho Spodoptera frugiperda (J.E. Smith, foi avaliado em condições de laboratório. As folhas de milho foram imersas em diferentes concentrações (0,0001%; 0,0008%; 0,006%; 0,05%; 0,4% e 3% desse extrato e oferecidas a lagartas recém-eclodidas e com dez dias de idade, avaliando-se a duração e viabilidade das fases larval e pupal e a massa de pupas. A concentração letal 50 (CL50 estimada para lagartas com sete dias de idade foi de 0,048%. Verificou-se que o extrato causou mortalidade larval de 100% (em concentração igual ou superior a 0,05%, afetou a sobrevivência e o desenvolvimento do inseto (na concentração de 0,006% e não provocou qualquer efeito no mesmo, em concentração igual ou inferior a 0,0008%. Lagartas alimentadas desde a eclosão foram mais afetadas do que as alimentadas a partir dos dez dias.

Chemistry of the uranyl group. VI. Complexes of uranyl with hexamethylphosphoramide and urea

Energy Technology Data Exchange (ETDEWEB)

Zarli, B; Dall' olio, G; Sindellari, L [Consiglio Nazionale delle Ricerche, Padua (Italy). Lab. di Chimica e Tecnologia dei Radioelementi

1976-01-01

Some uranyl complexes with hexamethylphosphoramide (HMPA) and urea were prepared and characterized. The compounds with the former ligand have the general formula UO/sub 2/X/sub 2/.HMPA (where X = (C/sub 2/H/sub 5/)/sub 2/NCSe/sub 2//sup -/, (C/sub 2/H/sub 5/)/sub 2/NCS/sub 2//sup -/ or CH/sub 3/COO/sup -/). For the acetato derivatives a dimeric acetato-bridged structure is suggested. Some properties of UO/sub 2/(NO/sub 3/)/sub 2/.2(HMPA) are also described. With the latter ligand, in addition to the complexes UO/sub 2/(NO/sub 3/)/sub 2/.2urea and (UO/sub 2/(urea)/sub 4/(H/sub 2/0))(NO/sub 3/)/sub 2/ already known, the novel complexes UO/sub 2/(pycrate)/sub 2/.4urea and (UO/sub 2/(CH/sub 3/COO)/sub 2/.urea)sub(n) (where n is probably 2) have been prepared. All attempts to obtain urea complexes of uranyl diethyldithio- or diethyldiselenocarbamate failed and only adducts of unsatisfactory stoichiometry were isolated.

Remarks on crack-bridging concepts

International Nuclear Information System (INIS)

Bao, G.; Suo, Z.

1992-01-01

The article draws upon recent work by us and our colleagues on metal and ceramic matrix composites for high temperature engines. The central theme here is to deduce mechanical properties, such as toughness, strength and notch-ductility, from bridging laws that characterize inelastic processes associated with fracture. A particular set of normalization is introduced to present the design charts, segregating the roles played by the shape, and the scale, of a bridging law. A single material length, γ 0 E/σ 0 , emerges, where γ 0 is the limiting-separation, σ 0 the bridging-strength, and E the Young's modulus of the solid. It is the huge variation of this length-from a few manometers for atomic bond, to a meter for cross-over fibers - that underlies the richness in material behaviors. Under small-scale bridging conditions, γ 0 E/σ 0 is the only basic length scale in the mechanics problem and represents, with a pre-factor about 0.4, the bridging zone size. A catalog of small-scale bridging solutions is compiled for idealized bridging laws. Large-scale bridging introduces a dimensionless group, a/(γ 0 E/σ 0 ), where a is a length characterizing the component. The group plays a major role in all phenomena associated with bridging, and provides a focus of discussion in this article. For example, it quantifies the bridging scale when a is the unbridged crack length, and notch-sensitivity when a is hole radius. The difference and the connection between Irwin's fracture mechanics and crack bridging concepts are discussed. It is demonstrated that fracture toughness and resistance curve are meaningful only when small-scale bridging conditions prevail, and therefore of limited use in design with composites. Many other mechanical properties of composites, such as strength and notch-sensitivity, can be simulated by invoking large-scale bridging concepts. 37 refs., 21 figs., 3 tabs

Copper(II) catalysis in cyanide conversion into ethyl carbamate in spirits and relevant reactions.

Science.gov (United States)

Aresta, M; Boscolo, M; Franco, D W

2001-06-01

The role of copper(II) species in the oxidation of inorganic cyanide to cyanate and in the conversion of cyanate or urea into ethyl carbamate was investigated. The oxidation process has been shown to be independent from the dissolved oxygen. Elemental analysis and infrared spectroscopy have shown the formation of a mixed copper carbonate/hydroxide in the process of oxidation of cyanide to cyanate in water/ethanol. The complexation to Cu(II) of cyanate formed upon cyanide oxidation makes the former more susceptible to nucleophilic attack from ethanol, with conversion into ethyl carbamate. Comparatively, urea has a minor role with respect to cyanide in the formation of ethyl carbamate. Therefore, the urea present in some samples of Brazilian sugar cane spirit (cachaça) has been shown to have almost no influence on the ethyl carbamate content of cachaças, which comes essentially from cyanide. Fe(II,III) affords results similar to those found with Cu(II). Some suggestions are presented to avoid ethyl carbamate formation in spirits during distillation.

Interaction between metals and nucleic acids. Part 3. Synthesis and structural studies of copper(II) complexes with Schiff base ligands derived from barbituric acid

Energy Technology Data Exchange (ETDEWEB)

Sasaki, I.; Gaudemer, A.; Chiaroni, A.; Riche, C.

1986-02-17

Schiff bases have been prepared from 5-formylbarbituric acid and 5-formyl-1,3-dimethyl-barbituric acid and various di- or tri-amines. The structure of the corresponding copper(II) complexes have been established by elemental analysis and spectroscopic methods. The molecular structure of one of the complexes, Cu(DiMeBardpt), was determined by X-ray diffraction. Electrochemical study shows that these complexes are reduced at slightly more negative potentials than the corresponding complexes obtained from uracil, which suggests that these new ligands are better electron-donors.

49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Interlocking Standards § 236.312 Movable bridge, interlocking of signal...

Synthesis and properties of complexes of copper(II), nickel(II), cobalt(II) and uranyl ions with 3-(p-tolylsulphonamido)rhodamine

International Nuclear Information System (INIS)

El-Bindary, A.A.; El-Sonbati, A.Z.

2000-01-01

Metal complexes of copper(II), nickel(II), cobalt(II) and uranyl ions with 3-(p-tolylsulphonamido)rhodamine (HL) have been prepared and characterized by chemical and thermal analyses, molar conductivity , magnetic susceptibility measurements, and infrared, electronic and EPR spectra. The visible and EPR spectra indicated that the Cu(II) complex has a tetragonal geometry. From EPR spectrum of the Cu(II) complex,various parameters were calculated. The crystal field parameters of Ni(II) complex were calculated and were found to agree fairly well with the values reported for known square pyramidal complexes. The infrared spectral studies showed a monobasic bidentate behaviour with the oxygen and nitrogen donor system. Thermal stabilities of the complexes are also reported. (author)

Cooperativity of complex salt bridges

OpenAIRE

Gvritishvili, Anzor G.; Gribenko, Alexey V.; Makhatadze, George I.

2008-01-01

The energetic contribution of complex salt bridges, in which one charged residue (anchor residue) forms salt bridges with two or more residues simultaneously, has been suggested to have importance for protein stability. Detailed analysis of the net energetics of complex salt bridge formation using double- and triple-mutant cycle analysis revealed conflicting results. In two cases, it was shown that complex salt bridge formation is cooperative, i.e., the net strength of the complex salt bridge...

Comprehensive evaluation of fracture critical bridges.

Science.gov (United States)

2014-02-01

Two-girder steel bridges are classified as fracture critical bridges based on the definition given in the AASHTO LRFD Bridge Design Specifications. In a fracture critical bridge a failure of a tension member leads to collapse of the bridge. However, ...

Stability constants of glutarate complexes of copper(II), zinc(II), cobalt(II) and uranyl(II) by paper electrophoresis

International Nuclear Information System (INIS)

Singh, R.K.P.; Yadava, J.R.; Yadava, K.L.

1981-01-01

Stability constants of Copper(II), Zinc(II), Cobalt(II) and Uranyl(II) glutarates have been determined by paper electrophoresis. Glutaric acid (0.005 mol dmsup(-3)) was added to the background electrolyte : 0.1 mol dmsup(-3) HClO 4 . The proportions of (CH 2 ) 3 COOH COO - and (CH 2 ) 3 C 2 O 4 2- were varied by changing the pH of the electrolyte. These anions yielded the complexes Cu(CH 2 ) 3 C 2 O 4 , [Zn(CH 2 ) 3 COOH COO] + [Co(CH 2 ) 3 COOH COO] + and UO 2 (CH 2 ) 3 C 2 O 4 whose stability constants are found to be 10sup(3.9), 10sup(2.9), 10sup(2.7) and 10sup(13.5) respectively. (author)

Timber in Bridge Structures

OpenAIRE

Detkin, Viktoria

2016-01-01

The purpose of this final year project was to study the properties of timber as a structural material and the suitability of wood in load bearing members for bridge structures. For a case study, an existing timber bridge was selected. Due to its condition the bridge should be replaced. The design of a new bridge with steel beams holding a glulam deck was made. During the case study the replacement of steel beams by glulam timber ones was discussed. Some calculations were made in order to ...

Field performance of timber bridges. 16, North Siwell Road stress-laminated bridge

Science.gov (United States)

J. A. Kainz

The North Siwell Road bridge was constructed during December 1994 in Hinds County, Mississippi. The bridge is a single-span, stress-laminated T-beam structure that measures 9.1 m (30 ft) long and 8.7 m (28.5 ft) wide. Performance of the bridge was monitored for 24 months, beginning at the time of installation. Monitoring involved gathering and evaluating data relative...

Field performance of timber bridges. 10, Sanborn Brook stress-laminated deck bridge

Science.gov (United States)

P. D. Hilbrich Lee; J. P. Wacker; M. A. Ritter

The Sanborn Brook bridge was constructed in August 1991, 10 miles northeast of Concord, New Hampshire, as part of the demonstration timber bridge program of the USDA Forest Service. The bridge is a simple-span, double-lane, stress-laminated deck superstructure constructed from Southern Pine lumber and is approximately 25 ft long and 28 ft wide with a skew of 14 degrees...

Simulation of multivariate diffusion bridges

DEFF Research Database (Denmark)

Bladt, Mogens; Finch, Samuel; Sørensen, Michael

We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously...... proposed simulation method for one-dimensional bridges to the mulit-variate setting. First a method of simulating approzimate, but often very accurate, diffusion bridges is proposed. These approximate bridges are used as proposal for easily implementable MCMC algorithms that produce exact diffusion bridges...

Steel-soil composite bridge

DEFF Research Database (Denmark)

Du, Guangli; Pettersson, Lars; Karoumi, Raid

2017-01-01

viability, while their environmental performance is overlooked. Today’s designers are urged to seek new design options to reduce the environmental burdens. Sweden owns more than 24574 bridges and most of them are short spans. Among them, the slab frame bridge (CFB) is a common solution. Soil steel composite...... bridge (SSCB), alternatively, is a functionally equivalent solution to CFB and shows advantages in low cost and easy construction. This paper compares the environmental performance between these two bridge types based on life cycle assessment (LCA). The analysis and result shows that, the SSCB...

Building water bridges in air: Electrohydrodynamics of the floating water bridge

Science.gov (United States)

Marín, Álvaro G.; Lohse, Detlef

2010-12-01

The interaction of electrical fields and liquids can lead to a phenomenon that defies intuition. Some famous examples can be found in electrohydrodynamics as Taylor cones, whipping jets, or noncoalescing drops. A less famous example is the floating water bridge: a slender thread of water held between two glass beakers in which a high voltage difference is applied. Surprisingly, the water bridge defies gravity even when the beakers are separated at distances up to 2 cm. In this paper, experimental measurements and simple models are proposed and discussed for the stability of the bridge and the source of the flow, revealing an important role of polarization forces on the stability of the water bridge. On the other hand, the observed flow can only be explained due to the non-negligible free charge present in the surface. In this sense, the floating water bridge can be considered as an extreme case of a leaky dielectric liquid [J. R. Melcher and G. I. Taylor, Annu. Rev. Fluid Mech. 1, 111 (1969)].

National Bridge Inventory (NBI) Bridges

Data.gov (United States)

Department of Homeland Security — The NBI is a collection of information (database) describing the more than 600,000 of the Nation's bridges located on public roads, including Interstate Highways,...

Electronic and magnetic properties of infinite 1D chains of paddlewheel carboxylates M2(COOR)4 (M = Mo, W, Ru, Rh, Ir, Cu)

KAUST Repository

Peskov, Maxim

2013-03-14

Dinuclear complexes of transition metals bridged by four carboxylate-groups are examples of stable atomic configurations serving as fundamental building blocks of catalysts and prototypical molecular electronic devices. The electronic structure and magnetic properties of many molecular tetracarboxylate complexes were meticulously studied; however, the properties of the one-dimensional (1D) polymeric chain of associated tetracarboxylates have so far evaded much attention. Using periodic density-functional theory calculations, we analyze the electronic structure of condensed tetracarboxylates Mo(II), W(II), Ru(II), Rh(II), Ir(II), and Cu(II). The relationship between crystal structure of the polymerized tetracarboxylates and the electronic properties of the metal-metal bond in the M24+ core is studied. The electronic effects emanating from the association of dinuclear transition metal tetracarboxylates are important for designing molecular electronic devices. In this study, its influence on both direct and indirect metal-metal interactions, and the electronic structure, in particular transport properties, is discussed. © 2013 American Chemical Society.

Wright-Fisher diffusion bridges.

Science.gov (United States)

Griffiths, Robert C; Jenkins, Paul A; Spanò, Dario

2017-10-06

The trajectory of the frequency of an allele which begins at x at time 0 and is known to have frequency z at time T can be modelled by the bridge process of the Wright-Fisher diffusion. Bridges when x=z=0 are particularly interesting because they model the trajectory of the frequency of an allele which appears at a time, then is lost by random drift or mutation after a time T. The coalescent genealogy back in time of a population in a neutral Wright-Fisher diffusion process is well understood. In this paper we obtain a new interpretation of the coalescent genealogy of the population in a bridge from a time t∈(0,T). In a bridge with allele frequencies of 0 at times 0 and T the coalescence structure is that the population coalesces in two directions from t to 0 and t to T such that there is just one lineage of the allele under consideration at times 0 and T. The genealogy in Wright-Fisher diffusion bridges with selection is more complex than in the neutral model, but still with the property of the population branching and coalescing in two directions from time t∈(0,T). The density of the frequency of an allele at time t is expressed in a way that shows coalescence in the two directions. A new algorithm for exact simulation of a neutral Wright-Fisher bridge is derived. This follows from knowing the density of the frequency in a bridge and exact simulation from the Wright-Fisher diffusion. The genealogy of the neutral Wright-Fisher bridge is also modelled by branching Pólya urns, extending a representation in a Wright-Fisher diffusion. This is a new very interesting representation that relates Wright-Fisher bridges to classical urn models in a Bayesian setting. Copyright © 2017 Elsevier Inc. All rights reserved.

National Bridge Inventory System (NBI)

Data.gov (United States)

Department of Transportation — The NBI System is the collection of bridge inspection information and costs associated with bridge replacements of structurally deficient bridges on and off the NHS....

Extracorporeal Life Support Bridge to Ventricular Assist Device: The Double Bridge Strategy.

Science.gov (United States)

Marasco, Silvana F; Lo, Casey; Murphy, Deirdre; Summerhayes, Robyn; Quayle, Margaret; Zimmet, Adam; Bailey, Michael

2016-01-01

In patients requiring left ventricular assist device (LVAD) support, it can be difficult to ascertain suitability for long-term mechanical support with LVAD and eventual transplantation. LVAD implantation in a shocked patient is associated with increased morbidity and mortality. Interest is growing in the utilization of extracorporeal life support (ECLS) as a bridge-to-bridge support for these critically unwell patients. Here, we reviewed our experience with ECLS double bridging. We hypothesized that ECLS double bridging would stabilize end-organ dysfunction and reduce ventricular assist device (VAD) implant perioperative mortality. We conducted a retrospective review of prospectively collected data for 58 consecutive patients implanted with a continuous-flow LVAD between January 2010 and December 2013 at The Alfred Hospital, Melbourne, Victoria, Australia. Twenty-three patients required ECLS support pre-LVAD while 35 patients underwent LVAD implantation without an ECLS bridge. Preoperative morbidity in the ECLS bridge group was reflected by increased postoperative intensive care duration, blood loss, blood product use, and postoperative renal failure, but without negative impact upon survival when compared with the no ECLS group. ECLS stabilization improved end-organ function pre-VAD implant with significant improvements in hepatic and renal dysfunction. This series demonstrates that the use of ECLS bridge to VAD stabilizes end-organ dysfunction and reduces VAD implant perioperative mortality from that traditionally reported in these "crash and burn" patients. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Estudo da densidade de ligações Cruzadas em géis superabsorventes obtidos do acetato de celulose Study of the crosslinking density in superabsorbent gels obtained from cellulose acetate

Directory of Open Access Journals (Sweden)

André M. Senna

2013-01-01

Full Text Available Neste trabalho foram realizadas sínteses de géis derivados de acetato de celulose (AC com grau de substituição (GS 2,5 por intermédio de reações de reticulação via esterificação. Os grupos hidroxílicos livres do AC foram reagidos com o dianidrido do ácido 1, 2, 4, 5 benzenotetracarboxílico (PMDA em meio homogêneo. As caracterizações foram realizadas por TGA (Análise termogravimétrica, espectroscopia na região do infravermelho (FTIR, retro titulação para determinar o grau de substituição do AC e microscopia de força atômica (AFM. Os géis foram sintetizados com as seguintes razões estequiométricas: [1:1], [1:2/3], [1:3] e [3:1] mol de PMDA/mol de OH livre respectivamente. A base da teoria de Flory-Rehner foi empregada para determinar ligações cruzadas nos géis. Os resultados de AFM mostram topografias distintas quando são comparados os géis entre si e quando os géis são comparados ao polímero de acetato de celulose. Este trabalho foi motivado pela importância tecnológica de polímeros de fontes renováveis como a celulose, em que um derivado de celulose foi usado para obter um polímero promissor para liberação controlada de medicamentos e adsorção de metais pesados em meio aquoso. Uma das vantagens deste polímero derivado do acetato de celulose é o emprego de poucas etapas na sua síntese.This work reports the synthesis of gels derived from cellulose acetate (CA with degree of substitution (DS 2.5 through esterification and crosslinking reactions. The free hydroxyl groups were reacted by using dianhydride of acid 1,2,4,5 benzenotetracarboxylic (PMDA as modifier in a homogeneous media. Characterization was performed with Thermogravimetric Analysis (TGA, Fourier Transform Infrared Spectroscopy (FTIR, retrotitration (known as back titration to determine the degree of substitution of AC and atomic force microscopy (AFM. The gels were synthesized with the following stoichiometric ratios: [1:1], [1:2/3], [1

Estudo da densidade de ligações Cruzadas em géis superabsorventes obtidos do acetato de celulose Study of the crosslinking density in superabsorbent gels obtained from cellulose acetate

Directory of Open Access Journals (Sweden)

André M. Senna

2012-01-01

Full Text Available Neste trabalho foram realizadas sínteses de géis derivados de acetato de celulose (AC com grau de substituição (GS 2,5 por intermédio de reações de reticulação via esterificação. Os grupos hidroxílicos livres do AC foram reagidos com o dianidrido do ácido 1, 2, 4, 5 benzenotetracarboxílico (PMDA em meio homogêneo. As caracterizações foram realizadas por TGA (Análise termogravimétrica, espectroscopia na região do infravermelho (FTIR, retro titulação para determinar o grau de substituição do AC e microscopia de força atômica (AFM. Os géis foram sintetizados com as seguintes razões estequiométricas: [1:1], [1:2/3], [1:3] e [3:1] mol de PMDA/mol de OH livre respectivamente. A base da teoria de Flory-Rehner foi empregada para determinar ligações cruzadas nos géis. Os resultados de AFM mostram topografias distintas quando são comparados os géis entre si e quando os géis são comparados ao polímero de acetato de celulose. Este trabalho foi motivado pela importância tecnológica de polímeros de fontes renováveis como a celulose, em que um derivado de celulose foi usado para obter um polímero promissor para liberação controlada de medicamentos e adsorção de metais pesados em meio aquoso. Uma das vantagens deste polímero derivado do acetato de celulose é o emprego de poucas etapas na sua síntese.This work reports the synthesis of gels derived from cellulose acetate (CA with degree of substitution (DS 2.5 through esterification and crosslinking reactions. The free hydroxyl groups were reacted by using dianhydride of acid 1,2,4,5 benzenotetracarboxylic (PMDA as modifier in a homogeneous media. Characterization was performed with Thermogravimetric Analysis (TGA, Fourier Transform Infrared Spectroscopy (FTIR, retrotitration (known as back titration to determine the degree of substitution of AC and atomic force microscopy (AFM. The gels were synthesized with the following stoichiometric ratios: [1:1], [1:2/3], [1

Bridge maintenance to enhance corrosion resistance and performance of steel girder bridges

Science.gov (United States)

Moran Yanez, Luis M.

The integrity and efficiency of any national highway system relies on the condition of the various components. Bridges are fundamental elements of a highway system, representing an important investment and a strategic link that facilitates the transport of persons and goods. The cost to rehabilitate or replace a highway bridge represents an important expenditure to the owner, who needs to evaluate the correct time to assume that cost. Among the several factors that affect the condition of steel highway bridges, corrosion is identified as the main problem. In the USA corrosion is the primary cause of structurally deficient steel bridges. The benefit of regular high-pressure superstructure washing and spot painting were evaluated as effective maintenance activities to reduce the corrosion process. The effectiveness of steel girder washing was assessed by developing models of corrosion deterioration of composite steel girders and analyzing steel coupons at the laboratory under atmospheric corrosion for two alternatives: when high-pressure washing was performed and when washing was not considered. The effectiveness of spot painting was assessed by analyzing the corrosion on steel coupons, with small damages, unprotected and protected by spot painting. A parametric analysis of corroded steel girder bridges was considered. The emphasis was focused on the parametric analyses of corroded steel girder bridges under two alternatives: (a) when steel bridge girder washing is performed according to a particular frequency, and (b) when no bridge washing is performed to the girders. The reduction of structural capacity was observed for both alternatives along the structure service life, estimated at 100 years. An economic analysis, using the Life-Cycle Cost Analysis method, demonstrated that it is more cost-effective to perform steel girder washing as a scheduled maintenance activity in contrast to the no washing alternative.

Strength monitoring of bridge constructions and features of its application. Part 2. Continuous monitoring of bridge construction status

Directory of Open Access Journals (Sweden)

Ovchinnikov Igor Georgievich

2014-06-01

Full Text Available The article describes a system of continuous monitoring of bridge constructions — a system of observation over the operating conditions and behavior of the bridge structure, which is aimed at ensuring the preservation of its functional application properties within the specified limits, realized on the continuous, long-term basis with the use of instrumentation and ensures on-line presentation of information on the status of structure. To illustrate, one may consider the existing systems of continuous monitoring for a number of bridge constructions in the United States, Japan, Europe, South Korea, Greece and Russia. The article suggests to examine the systems of continuous monitoring of «Commodore John Barry» truss bridge, «Akashi-Kaikyo» suspension bridge, «Siggenthal» reinforced-concrete arch bridge, «Nimhe» suspension bridge, «Jindo»cable-stayed bridge, «Yandzhon» suspension bridge, «Banghwa» bridge, «Seohae» bridge and «Rio-Antirrio» bridge. In addition one may consider monitoring of the longitudinal launching of the bridge superstructures over the Volga River near the village Pristannoye in Saratov region. Finally, it was drawn the conclusion that monitoring of bridge constructions from the standpoint of their consumers is aimed at solving such important problems as preservation of bridge structures, increase in service life of bridge structures through timely detection of faults and their elimination, as well as preservation of bridge structure carrying capacity by controlling their behavior during the operation and improving the efficiency of expenditure of monetary resources for repair activities by correct determination of time and type of the necessary repair.

Field performance of timber bridges. 15, Pueblo County, Colorado, stress-laminated deck bridge

Science.gov (United States)

L. E. Hislop

The Pueblo County 204B bridge was constructed in March 1990 in Pueblo, Colorado, as a demonstration bridge under the USDA Forest Service Timber Bridge Initiative. The stress-laminated deck superstructure is approximately 10 m long, 9 m wide, and 406 mm deep, with a skew of 10 degrees. Performance monitoring was conducted for 3 years, beginning at...

Principles of Bridge Reliability

DEFF Research Database (Denmark)

Thoft-Christensen, Palle; Nowak, Andrzej S.

The paper gives a brief introduction to the basic principles of structural reliability theory and its application to bridge engineering. Fundamental concepts like failure probability and reliability index are introduced. Ultimate as well as serviceability limit states for bridges are formulated......, and as an example the reliability profile and a sensitivity analyses for a corroded reinforced concrete bridge is shown....

Design and construction of superstructure in prestressed concrete cable-stayed bridge. ; Aomori Bay Bridge. PC shachokyo jobuko no sekkei to seko. ; Aomori Bay Bridge

Energy Technology Data Exchange (ETDEWEB)

Ishibashi, T.; Fujimori, S.; Oba, M.; Tsuyoshi, T. (East Japan Railway Co., Tokyo (Japan))

1991-12-01

Aomori Bay Bridge is a 1,219m long elevated bridge, a part of No.2 Bay Highway of 1,993m in total length crossing over Aomori railway station which was planned in ordecr to integrate the port facilities of Aomori Harbor and expedite cargo traffic smoothly. Of this Bay Bridge, its main bridge portion crossing over Aomori railway station and the sea area was planned as a continuous prestressed concrete cable-stayed bridge of 498m in total length and consisting of three portions including the central portion in which the main span between the central bridge piers was 240m. It is scheduled to open in the summer of 1992. With regard to the design of this bridge, special care for the view of the bridge has been taken covering from the structure style to the accessories. For this bridge, a large scale underground continuous wall solid base with a box-shaped section consisting of 6 chambers was adopted for the base of a main tower. It has the cantilever suspension structure of the wide girder with the inverted Y-shaped pylons. For its stav cable, was adopted a large capacity stay cable with standard tensile strength of 1,942 fabricated on the site and for its covering tube, a FRP tube was adopted. In this article, the construction of the main girder and stay cables, and the construction control during their installation by projection are reported. 7 refs., 14 figs., 9 tabs.

Impact Coefficient Analysis of Long-Span Railway Cable-Stayed Bridge Based on Coupled Vehicle-Bridge Vibration

Directory of Open Access Journals (Sweden)

Yongle Li

2015-01-01

Full Text Available Compared with medium and small span bridges, very limited attention has been paid on the research of the impact coefficient of long-span railway bridges. To estimate the impact effects of long-span railway bridges subjected to moving vehicles, a real long-span railway cable-stayed bridge is regarded as the research object in this study, and a coupled model of vehicle-bridge system is established. The track irregularities are taken as the system excitation and the dynamic responses of the vehicle-bridge system are calculated. The impact effects on main girder, stayed cable, bearings, and bridge tower are discussed at various vehicle speeds. The results show that different components of the long-span railway cable-stayed bridge have different impact coefficients. Even for each part, the impact coefficient is also different at different local positions. It reveals that the impact coefficients in the actual situation may have significant differences with the related code clauses in the present design codes.

Field performance of timber bridges. 8, Lynches Woods Park stress-laminated deck bridge

Science.gov (United States)

J. P. Wacker; M. A. Ritter; D. Conger

The Lynches Woods Park bridge was constructed during the summer of 1990 in Newberry, South Carolina. It is a single-span, single-lane, stress-laminated deck superstructure that measures approximately 30 ft long, 16 ft wide, and 14 in. deep. The bridge is unique in that is one of the first known stress-laminated deck bridges to be constructed of Southern Pine lumber...

Salt-bridge energetics in halophilic proteins.

Science.gov (United States)

Nayek, Arnab; Sen Gupta, Parth Sarthi; Banerjee, Shyamashree; Mondal, Buddhadev; Bandyopadhyay, Amal K

2014-01-01

Halophilic proteins have greater abundance of acidic over basic and very low bulky hydrophobic residues. Classical electrostatic stabilization was suggested as the key determinant for halophilic adaptation of protein. However, contribution of specific electrostatic interactions (i.e. salt-bridges) to overall stability of halophilic proteins is yet to be understood. To understand this, we use Adaptive-Poison-Boltzmann-Solver Methods along with our home-built automation to workout net as well as associated component energy terms such as desolvation energy, bridge energy and background energy for 275 salt-bridges from 20 extremely halophilic proteins. We then perform extensive statistical analysis on general and energetic attributes on these salt-bridges. On average, 8 salt-bridges per 150 residues protein were observed which is almost twice than earlier report. Overall contributions of salt-bridges are -3.0 kcal mol-1. Majority (78%) of salt-bridges in our dataset are stable and conserved in nature. Although, average contributions of component energy terms are equal, their individual details vary greatly from one another indicating their sensitivity to local micro-environment. Notably, 35% of salt-bridges in our database are buried and stable. Greater desolvation penalty of these buried salt-bridges are counteracted by stable network salt-bridges apart from favorable equal contributions of bridge and background terms. Recruitment of extensive network salt-bridges (46%) with a net contribution of -5.0 kcal mol-1 per salt-bridge, seems to be a halophilic design wherein favorable average contribution of background term (-10 kcal mol-1) exceeds than that of bridge term (-7 kcal mol-1). Interiors of proteins from halophiles are seen to possess relatively higher abundance of charge and polar side chains than that of mesophiles which seems to be satisfied by cooperative network salt-bridges. Overall, our theoretical analyses provide insight into halophilic signature in its

Syntheses, crystal structures and properties of novel copper(II) complexes obtained by reactions of copper(II) sulfate pentahydrate with tripodal ligands.

Science.gov (United States)

Zhao, Wei; Fan, Jian; Song, You; Kawaguchi, Hiroyuki; Okamura, Taka-aki; Sun, Wei-Yin; Ueyama, Norikazu

2005-04-21

Three novel metal-organic frameworks (MOFs), [Cu(1)SO4].H2O (4), [Cu2(2)2(SO4)2].4H2O (5) and [Cu(3)(H2O)]SO4.5.5H2O (6), were obtained by hydrothermal reactions of CuSO4.5H2O with the corresponding ligands, which have different flexibility. The structures of the synthesized complexes were determined by single-crystal X-ray diffraction analyses. Complex 4 has a 2D network structure with two types of metallacycles. Complex 5 also has a 2D network structure in which each independent 2D sheet contains two sub-layers bridged by oxygen atoms of the sulfate anions. Complex 6 has a 2D puckered structure in which the sulfate anions serve as counter anions, which are different from those in complexes 4 (terminators) and 5 (bridges). The different structures of complexes 4, 5 and 6 indicate that the nature of organic ligands affected the structures of the assemblies greatly. The magnetic behavior of complex 5 and anion-exchange properties of complex 6 were investigated.

Bridge the Gap

DEFF Research Database (Denmark)

Marselis, Randi

2017-01-01

This article focuses on photo projects organised for teenage refugees by the Society for Humanistic Photography (Berlin, Germany). These projects, named Bridge the Gap I (2015), and Bridge the Gap II (2016), were carried out in Berlin and brought together teenagers with refugee and German...

Bridge technology report

CERN Document Server

2013-01-01

Please note this is a Short Discount publication. As LANs have proliferated, new technologies and system concepts have come to the fore. One of the key issues is how to interconnect networks. One means of interconnection is to use a 'bridge'. Other competing technologies are repeaters, routers, and gateways. Bridges permit traffic isolation, connect network segments together and operate at the MAC layer. Further, because they operate at the MAC layer, they can handle a variety of protocols such as TCP/IP, SNA, and X.25. This report focuses on the specific technology of bridging two netw

Field performance of timber bridges. 12, Christian Hollow stress-laminated box-beam bridge

Science.gov (United States)

J. P. Wacker; S. C. Catherman; R. G. Winnett

In January 1992, the Christian Hollow bridge was constructed in Steuben County, New York. The bridge is a single-span, stress-laminated box-beam superstructure that is 9.1 m long, 9.8 m wide, and 502 mm deep (30 ft long, 32 ft wide, and 19-3/4 in. deep). The performance of the bridge was continuously monitored for 28 months, beginning shortly after installation....

Road Bridges and Culverts, Bridge dataset only includes bridges maintained by Johnson County Public Works in the unincorporated areas, Published in Not Provided, Johnson County Government.

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — Road Bridges and Culverts dataset current as of unknown. Bridge dataset only includes bridges maintained by Johnson County Public Works in the unincorporated areas.

Laboratory Testing of Precast Bridge Beck Panel Transverse Connections for Use in Accelerated Bridge Construction

OpenAIRE

Porter, Scott D.

2009-01-01

Precast concrete bridge deck panels have been used for decades to accelerate bridge construction. Cracking of the transverse connection between panels is a common problem that can damage deck overlays and cause connection leaking leading to corrosion of lower bridge elements. To better understand the behavior of bridge deck transverse female-to-female connections, shear and moment lab testing were performed at Utah State University for the Utah Department of Transportation. Two existing UDOT ...

Human Errors and Bridge Management Systems

DEFF Research Database (Denmark)

Thoft-Christensen, Palle; Nowak, A. S.

on basis of reliability profiles for bridges without human errors are extended to include bridges with human errors. The first rehabilitation distributions for bridges without and with human errors are combined into a joint first rehabilitation distribution. The methodology presented is illustrated...... for reinforced concrete bridges....

A bridge with a view, a view with a bridge : Identifying design considerations for bridges to strengthen regional identity

NARCIS (Netherlands)

Smits, J.E.P.; van der Hoeven, F.D.

2015-01-01

This paper discusses design considerations for creating high quality infrastructural artefacts with an emphasis on bridges. The authors pursue a design study and analysis approach to highlight the specifics of infrastructure design for regional identity, based on their own work on a bridge

Precast concrete elements for accelerated bridge construction : laboratory testing, field testing, evaluation of a precast concrete bridge, Madison County bridge.

Science.gov (United States)

2009-01-01

The importance of rapid construction technologies has been recognized by the Federal Highway Administration (FHWA) and the Iowa : DOT Office of Bridges and Structures. Recognizing this a two-lane single-span precast box girder bridge was constructed ...

BUILDING A BETTER GLUTEAL BRIDGE: ELECTROMYOGRAPHIC ANALYSIS OF HIP MUSCLE ACTIVITY DURING MODIFIED SINGLE-LEG BRIDGES.

Science.gov (United States)

Lehecka, B J; Edwards, Michael; Haverkamp, Ryan; Martin, Lani; Porter, Kambry; Thach, Kailey; Sack, Richard J; Hakansson, Nils A

2017-08-01

Gluteal strength plays a role in injury prevention, normal gait patterns, eliminating pain, and enhancing athletic performance. Research shows high gluteal muscle activity during a single-leg bridge compared to other gluteal strengthening exercises; however, prior studies have primarily measured muscle activity with the active lower extremity starting in 90 ° of knee flexion with an extended contralateral knee. This standard position has caused reports of hamstring cramping, which may impede optimal gluteal strengthening. The purpose of this study was to determine which modified position for the single-leg bridge is best for preferentially activating the gluteus maximus and medius. Cross-Sectional. Twenty-eight healthy males and females aged 18-30 years were tested in five different, randomized single-leg bridge positions. Electromyography (EMG) electrodes were placed on subjects' gluteus maximus, gluteus medius, rectus femoris, and biceps femoris of their bridge leg (i.e., dominant or kicking leg), as well as the rectus femoris of their contralateral leg. Subjects performed a maximal voluntary isometric contraction (MVIC) for each tested muscle prior to performing five different bridge positions in randomized order. All bridge EMG data were normalized to the corresponding muscle MVIC data. A modified bridge position with the knee of the bridge leg flexed to 135 ° versus the traditional 90 ° of knee flexion demonstrated preferential activation of the gluteus maximus and gluteus medius compared to the traditional single-leg bridge. Hamstring activation significantly decreased (p bridge by flexing the active knee to 135 ° instead of 90 ° minimizes hamstring activity while maintaining high levels of gluteal activation, effectively building a bridge better suited for preferential gluteal activation. 3.

The violin bridge as filter.

Science.gov (United States)

Bissinger, George

2006-07-01

The violin bridge filter role was investigated using modal and acoustic measurements on 12 quality-rated violins combined with systematic bridge rocking frequency f(rock) and wing mass decrements deltam on four bridges for two other violins. No isolated bridge resonances were observed; bridge motions were complex (including a "squat" mode near 0.8 kHz) except for low frequency rigid body pivot motions, all more or less resembling rocking motion at higher frequencies. A conspicuous broad peak near 2.3 kHz in bridge driving point mobility (labeled BH) was seen for good and bad violins. Similar structure was seen in averaged bridge, bridge feet, corpus mobilities and averaged radiativity. No correlation between violin quality and BH driving point, averaged corpus mobility magnitude, or radiativity was found. Increasing averaged-over-f(rock) deltam(g) from 0 to 0.12 generally increased radiativity across the spectrum. Decreasing averaged-over-deltam f(rock) from 3.6 to 2.6 kHz produced consistent decreases in radiativity between 3 and 4.2 kHz, but only few-percent decreases in BH frequency. The lowest f(rock) values were accompanied by significantly reduced radiation from the Helmholtz A0 mode near 280 Hz; this, combined with reduced high frequency output, created overall radiativity profiles quite similar to "bad" violins among the quality-rated violins.

Crystal structure of a dinuclear CoII complex with bridging fluoride ligands: di-μ-fluorido-bis{tris[(6-methylpyridin-2-ylmethyl]amine}dicobalt(II bis(tetrafluoridoborate

Directory of Open Access Journals (Sweden)

Masataka Inomata

2014-11-01

Full Text Available Reaction of Co(BF42·6H2O with tris[(6-methylpyridin-2-ylmethyl]amiine in methanol results in a fluoride abstraction from BF4−, yielding the unexpected title compound, [Co2F2(C21H24N42](BF42. The complex cation consists of two inversion-related [Co(C21H24N4]2+ moieties bridged by a pair of fluoride ligands. The CoII cation is six-coordinated in a distorted octahedral geometry and forms a +II high-spin state. In the crystal, the complex cation and the BF4− anion are connected by C—H...F hydrogen bonds, forming a three-dimensional network. An intramolecular C—H...F hydrogen bond is also observed.

μ-(2,6-Bis{[3-(dimethylaminopropyl]iminomethyl}-4-methylphenolato-μ-hydroxido-bis[(thiocyanato-κNcopper(II

Directory of Open Access Journals (Sweden)

M. G. Meera

2013-10-01

Full Text Available In the title compound, [Cu2(C19H31N4O(OH(NCS2], the molecular structure of the dinuclear complex reveals two pentacoordinated CuII ions, which are bridged by the phenolate O atom of the ligand and by an exogenous hydroxide ion. The bridging atoms occupy equatorial positions in the coordination sphere of the metal atoms and complete the equatorial coordination planes with two ligand N atoms, the apical positions being occupied by thiocyanate N atoms. The crystal structure also features π–π stacking interactions involving the benzene rings with a centroid–centroid distance of 3.764 (4Å. The crystal studied was a non-merohedral twin, with a refined BASF value of 0.203 (2

Role of multiprotein bridging factor 1 in archaea: bridging the domains?

NARCIS (Netherlands)

Koning, de B.; Blombach, F.; Wu Hao,; Brouns, S.J.J.; Oost, van der J.

2009-01-01

MBF1 (multiprotein bridging factor 1) is a highly conserved protein in archaea and eukaryotes. It was originally identified as a mediator of the eukaryotic transcription regulator BmFTZ-F1 (Bombyx mori regulator of fushi tarazu). MBF1 was demonstrated to enhance transcription by forming a bridge

23 CFR 650.809 - Movable span bridges.

Science.gov (United States)

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Movable span bridges. 650.809 Section 650.809 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed bridge...

Sustainable Bridge Infrastructure Procurement

DEFF Research Database (Denmark)

Safi, Mohammed; Du, Guangli; Simonsson, Peter

2016-01-01

The lack of a flexible but systematic approach for integrating lifecycle aspects into bridge investment decisions is a major obstacle hindering the procurement of sustainable bridge infrastructures. This paper addresses this obstacle by introducing a holistic approach that agencies could use...... to procure the most “sustainable” (lifecycle-efficient) bridge through a fair design-build (D-B) tendering process, considering all the main aspects: life-cycle cost (LCC), service life-span, aesthetic demands and environmental impacts (LCA)....

Metal-containing radiation-sensitive polymers

International Nuclear Information System (INIS)

Lee, A.Y.

1986-01-01

The copolymers of methyl methacrylate with alkali metal salts (Na, K, and Cs) of methacrylic acid have been prepared by saponification K, and Cs) of methylacrylic acid have been prepared by saponification of the homopolymer poly(methyl methacrylate), PMMA. Low degrees of hydrolysis have been achieved by a heterogeneous system, and from the infrared spectra it has been confirmed that the ester groups of the methyl methacrylates are directly converted to the metal salts of methacrylic acid. These ionomers exhibit pseudo high molecular weights in gel permeation chromatogram, but no appreciable increase in intrinsic viscosities is observed in comparison to PMMA. The coordinated inorganic polymers poly[(dithio-2,2'-diacetato)bis(dimethylsulfoxide)dioxouranium(VI)] and poly[{methylenebis(thio)-2,2'-bis(acetato)}bis(dimethylsulfoxide)dioxouranium(VI)]have been synthesized in dimethyl sulfoxide solution with about 90% yield. The degree of polymerization and the number of average molecular weights of these polymers have been assessed by high resolution nuclear magnetic resonance, with which the acetato end group to the bridging ligand group ratios have been determined. The polymers bridging ligand group ratios have been determined. The polymers have been characterized by employing various techniques: infrared spectra, thermal gravimetric analysis, 13 C solid state nuclear magnetic resonance, and gel permeation chromatography. The prepared polymer samples have been subjected to various doses of 137 Cs gamma radiation under which the polymers predominantly undergo chain scission. The radiation sensitivities of the polymers are assessed by G values which are obtained from gel permeation chromatograms. These uranyl polymers exhibit unusually high G values

Nonlinearity in oscillating bridges

Directory of Open Access Journals (Sweden)

Filippo Gazzola

2013-09-01

Full Text Available We first recall several historical oscillating bridges that, in some cases, led to collapses. Some of them are quite recent and show that, nowadays, oscillations in suspension bridges are not yet well understood. Next, we survey some attempts to model bridges with differential equations. Although these equations arise from quite different scientific communities, they display some common features. One of them, which we believe to be incorrect, is the acceptance of the linear Hooke law in elasticity. This law should be used only in presence of small deviations from equilibrium, a situation which does not occur in widely oscillating bridges. Then we discuss a couple of recent models whose solutions exhibit self-excited oscillations, the phenomenon visible in real bridges. This suggests a different point of view in modeling equations and gives a strong hint how to modify the existing models in order to obtain a reliable theory. The purpose of this paper is precisely to highlight the necessity of revisiting the classical models, to introduce reliable models, and to indicate the steps we believe necessary to reach this target.

Coupling vibration research on Vehicle-bridge system

Science.gov (United States)

Zhou, Jiguo; Wang, Guihua

2018-01-01

The vehicle-bridge coupling system forms when vehicle running on a bridge. It will generate a relatively large influence on the driving comfort and driving safe when the vibration of the vehicle is bigger. A three-dimensional vehicle-bridge system with biaxial seven degrees of freedom has been establish in this paper based on finite numerical simulation. Adopting the finite element transient numerical simulation to realize the numerical simulation of vehicle-bridge system coupling vibration. Then, analyze the dynamic response of vehicle and bridge while different numbers of vehicles running on the bridge. Got the variation rule of vertical vibration of car body and bridge, and that of the contact force between the wheel and bridge deck. The research results have a reference value for the analysis about the vehicle running on a large-span cabled bridge.

Nondestructive testing for bridge diagnosis

International Nuclear Information System (INIS)

Oshima, Toshiyuki; Mikami, Shuichi; Yamazaki, Tomoyuki

1997-01-01

There are many motivations for bridge diagnosis using Nondestructive testing (NDT) to monitor its integrity. The measured frequency and damping on real bridge are compared in one figure as a function of span length and general aspects are explained. These date were measured in every construction of bridges and applied to design new bridges. Ultrasonic testing is also well used for concrete and steel members mainly to detect internal damages or delaminations. Detail analysis on reflected waves gives us more accurate information about the defect. Experimental results are shown as examples in this paper.

Salt bridges: geometrically specific, designable interactions.

Science.gov (United States)

Donald, Jason E; Kulp, Daniel W; DeGrado, William F

2011-03-01

Salt bridges occur frequently in proteins, providing conformational specificity and contributing to molecular recognition and catalysis. We present a comprehensive analysis of these interactions in protein structures by surveying a large database of protein structures. Salt bridges between Asp or Glu and His, Arg, or Lys display extremely well-defined geometric preferences. Several previously observed preferences are confirmed, and others that were previously unrecognized are discovered. Salt bridges are explored for their preferences for different separations in sequence and in space, geometric preferences within proteins and at protein-protein interfaces, co-operativity in networked salt bridges, inclusion within metal-binding sites, preference for acidic electrons, apparent conformational side chain entropy reduction on formation, and degree of burial. Salt bridges occur far more frequently between residues at close than distant sequence separations, but, at close distances, there remain strong preferences for salt bridges at specific separations. Specific types of complex salt bridges, involving three or more members, are also discovered. As we observe a strong relationship between the propensity to form a salt bridge and the placement of salt-bridging residues in protein sequences, we discuss the role that salt bridges might play in kinetically influencing protein folding and thermodynamically stabilizing the native conformation. We also develop a quantitative method to select appropriate crystal structure resolution and B-factor cutoffs. Detailed knowledge of these geometric and sequence dependences should aid de novo design and prediction algorithms. Copyright © 2010 Wiley-Liss, Inc.

An Expert System for Concrete Bridge Management

DEFF Research Database (Denmark)

Brito, J. de; Branco, F. A.; Thoft-Christensen, Palle

1997-01-01

The importance of bridge repair versus new bridge construction has risen in recent decades due to high deterioration rates that have been observed in these structures. Budgets both for building new bridges and keeping the existing ones are always limited. To help rational decision-making, bridge...... management systems are presently being implemented by bridge authorities in several countries. The prototype of an expert system for concrete bridge management is presented in this paper, with its functionality relying on two modules. The inspection module relies on a periodic acquisition of field...... information complemented by a knowledge-based interactive system, BRIDGE-1. To optimize management strategies at the headquarters, the BRIDGE-2 module was implemented, including three submodules: inspection strategy, maintenance and repair....

Model predictive control for a dual active bridge inverter with a floating bridge

OpenAIRE

Chowdhury, Shajjad; Wheeler, Patrick W.; Gerada, C.; Patel, Chintan

2016-01-01

This paper presents a Model Predictive Control technique applied to a dual active bridge inverter where one of the bridges is floating. The proposed floating bridge topology eliminates the need for isolation transformer in a dual inverter system and therefore reduces the size, weight and losses in the system. To achieve multilevel output voltage waveforms the floating inverter DC link capacitor is charged to the half of the main DC link voltage. A finite-set Model Predictive Control technique...

Bridge over troubled water?

DEFF Research Database (Denmark)

Svendsen, Gunnar Lind Haase; Nannestad, Peter; Svendsen, Gert Tinggaard

2008-01-01

The problem of integrating non-Western immigrants into Western welfare states is the focus of this paper. To address this issue, we suggest a social capital approach in which we apply the conceptual pair of bridging social capital (BR), which connects an individual to the broader social structure...... relationship between the levels of bridging and bonding capital, suggesting that bonding social capital in the immigrant group does not seem to impede the establishment of the bridging social capital needed for integration....

The dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase from Haemophilus influenzae is a dinuclear metallohydrolase.

Science.gov (United States)

Cosper, Nathaniel J; Bienvenue, David L; Shokes, Jacob E; Gilner, Danuta M; Tsukamoto, Takashi; Scott, Robert A; Holz, Richard C

2003-12-03

The Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra, of the dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) from Haemophilus influenzae have been recorded in the presence of one or two equivalents of Zn(II) (i.e. [Zn_(DapE)] and [ZnZn(DapE)]). The Fourier transforms of the Zn EXAFS are dominated by a peak at ca. 2.0 A, which can be fit for both [Zn_(DapE)] and [ZnZn(DapE)], assuming ca. 5 (N,O) scatterers at 1.96 and 1.98 A, respectively. A second-shell feature at ca. 3.34 A appears in the [ZnZn(DapE)] EXAFS spectrum but is significantly diminished in [Zn_(DapE)]. These data show that DapE contains a dinuclear Zn(II) active site. Since no X-ray crystallographic data are available for any DapE enzyme, these data provide the first glimpse at the active site of DapE enzymes. In addition, the EXAFS data for DapE incubated with two competitive inhibitors, 2-carboxyethylphosphonic acid and 5-mercaptopentanoic acid, are also presented.

Bridge and steel structures. History and vision on bridge erection; Kyoryo kokozobutsu. Kasetsu gijutsu no shorai

Energy Technology Data Exchange (ETDEWEB)

Mukai, S.; Hayashi, T. [Sumitomo Heavy Industries, Ltd., Tokyo (Japan)

1998-08-20

This paper describes the progress of bridge erection technology. It introduces the results of cable erection, rotated/extruded erection, and cantilever erection. The cable erection is a multi point suspension erection using cables. For the rotated/extruded erection, the monolithic construction is conducted on a working yard set in a right angle to the construction position, and the horizontal beams of the bridge piers (corbel girders) are constructed by the rotated method using a slewing base incorporated around the bridge piers at one side. For the construction of stiffening girders of Innoshima-ohashi Bridge of Honshu-Shikoku Joint Bridge in 1978, trussed face bar blocks were extruded from the main tower in order using a travel crane. For the suspension bridges and cable stayed bridges, main towers were erected using various types of cranes. The erection of Tamashima-ohashi Bridge with a weight of 500 ton using an offshore floating crane is introduced as a large block method. Analysis methods and measurement techniques at the site are used in order to analyze the shape in each step under the erection and to ensure the accurate final complete shape. Reduction of the construction cost, improvement of erection technology, and technology development for large-scale projects are subjects in the future. 22 refs., 8 figs., 1 tab.

Theoretical study of the magnetic behavior of hexanuclear Cu(II) and Ni(II) polysiloxanolato complexes.

Science.gov (United States)

Ruiz, Eliseo; Cano, Joan; Alvarez, Santiago; Caneschi, Andrea; Gatteschi, Dante

2003-06-04

A theoretical density functional study of the exchange coupling in hexanuclear polysiloxanolato-bridged complexes of Cu(II) and Ni(II) is presented. By calculating the energies of three different spin configurations, we can obtain estimates of the first-, second-, and third-neighbor exchange coupling constants. The study has been carried out for the complete structures of the Cu pristine cluster and of the chloroenclathrated Ni complex as well as for the hypotethical pristine Ni compound and for magnetically dinuclear analogues M(2)Zn(4) (M = Cu, Ni).

Dragon bridge - the world largest dragon-shaped (ARCH steel bridge as element of smart city

Directory of Open Access Journals (Sweden)

Chinh Luong Minh

2016-01-01

Full Text Available Dragon Bridge - The world’s largest dragon-shaped steel bridge, with an installation cost of $85 million USD, features 6 lanes for two separate directions, 666 meters of undulating steel in the shape of a dragon in the Ly Dynasty, the symbol of prosperity in Vietnamese culture. This unique and beautifully lit bridge, which also breathes fire and sprays water. It’s the purposeful integration of the lighting hardware articulates the dragon’s form, and the fire-breathing dragon head. This project transcends the notion of monumental bridge with dynamic colour-changing lighting, creating an iconic sculpture in the skyline that is both reverent and whimsical. The signature feature of the bridge was the massive undulating support structure resembling a dragon flying over the river. The dragon is prominent in Vietnamese culture as a symbol of power and nobility. Dragon Bridge stands out as a model of innovation. It has received worldwide attention in the design community and from the global media for its unique arch support system. Dragon Bridge serves as an example of how aesthetic quality of a design can serve cultural, economic and functional purposes. The article presents design solutions of the object and the evaluation of the technical condition before putting the facility into service.

Experimental investigation of different fill materials in arch bridges with particular focus on Pearl-Chain Bridges

DEFF Research Database (Denmark)

Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Hertz, Kristian Dahl

2016-01-01

Pearl-Chain Bridge technology is a recently developed prefabricated arch solution for road and railway bridges allowing faster, more environmentally friendly, and cheaper bridge construction. This study compared the strength and durability properties of three different types of fill material...

Bridge element deterioration rates.

Science.gov (United States)

2008-10-01

This report describes the development of bridge element deterioration rates using the NYSDOT : bridge inspection database using Markov chains and Weibull-based approaches. It is observed : that Weibull-based approach is more reliable for developing b...

Bridge-Vehicle Impact Assessment

Science.gov (United States)

2011-08-01

Bridges in New York State have been experiencing close to 200 bridge hits a year. These : accidents are attributed to numerous factors including: improperly stored equipment on trucks; : violation of vehicle posting signs; illegal commercial vehicles...

Bridge vehicle impact assessment.

Science.gov (United States)

2011-12-01

Bridges in New York State have been experiencing close to 200 bridge hits a year. These : accidents are attributed to numerous factors including: improperly stored equipment on trucks; : violation of vehicle posting signs; illegal commercial vehicles...

Wireless Smart Sensor Network System Using SmartBridge Sensor Nodes for Structural Health Monitoring of Existing Concrete Bridges

Science.gov (United States)

Gaviña, J. R.; Uy, F. A.; Carreon, J. D.

2017-06-01

There are over 8000 bridges in the Philippines today according to the Department of Public Works and Highways (DPWH). Currently, visual inspection is the most common practice in monitoring the structural integrity of bridges. However, visual inspections have proven to be insufficient in determining the actual health or condition of a bridge. Structural Health Monitoring (SHM) aims to give, in real-time, a diagnosis of the actual condition of the bridge. In this study, SmartBridge Sensor Nodes were installed on an existing concrete bridge with American Association of State Highway and Transportation Officials (AASHTO) Type IV Girders to gather vibration of the elements of the bridge. Also, standards on the effective installation of SmartBridge Sensor Nodes, such as location and orientation was determined. Acceleration readings from the sensor were then uploaded to a server, wherein they are monitored against certain thresholds, from which, the health of the bridge will be derived. Final output will be a portal or webpage wherein the information, health, and acceleration readings of the bridge will be available for viewing. With levels of access set for different types of users, the main users will have access to download data and reports. Data transmission and webpage access are available online, making the SHM system wireless.

Horizontal bridges in polar dielectric liquids

Science.gov (United States)

Woisetschläger, Jakob; Wexler, Adam D.; Holler, Gert; Eisenhut, Mathias; Gatterer, Karl; Fuchs, Elmar C.

2012-01-01

When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol, a horizontal bridge forms between the two beakers. By repeating a version of Pellat's experiment, it is shown that a horizontal bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon called a `floating water bridge' can be explained by the gradient of Maxwell pressure, replenishing the liquid within the bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges. The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds in the vicinity of the electrodes, is also discussed by two further experiments.

Highly selective and sensitive macrocycle-based dinuclear foldamer for fluorometric and colorimetric sensing of citrate in water.

Science.gov (United States)

Rhaman, Md Mhahabubur; Hasan, Mohammad H; Alamgir, Azmain; Xu, Lihua; Powell, Douglas R; Wong, Bryan M; Tandon, Ritesh; Hossain, Md Alamgir

2018-01-10

The selective detection of citrate anions is essential for various biological functions in living systems. A quantitative assessment of citrate is required for the diagnosis of various diseases in the human body; however, it is extremely challenging to develop efficient fluorescence and color-detecting molecular probes for sensing citrate in water. Herein, we report a macrocycle-based dinuclear foldamer (1) assembled with eosin Y (EY) that has been studied for anion binding by fluorescence and colorimetric techniques in water at neutral pH. Results from the fluorescence titrations reveal that the 1·EY ensemble strongly binds citrate anions, showing remarkable selectivity over a wide range of inorganic and carboxylate anions. The addition of citrate anions to the 1·EY adduct led to a large fluorescence enhancement, displaying a detectable color change under both visible and UV light in water up to 2 μmol. The biocompatibility of 1·EY as an intracellular carrier in a biological system was evaluated on primary human foreskin fibroblast (HF) cells, showing an excellent cell viability. The strong binding properties of the ensemble allow it to be used as a highly sensitive, detective probe for biologically relevant citrate anions in various applications.

LTBP bridge performance primer.

Science.gov (United States)

2013-12-01

"The performance of bridges is critical to the overall performance of the highway transportation system in the United States. However, many critical aspects of bridge performance are not well understood. The reasons for this include the extreme diver...

33 CFR 115.70 - Advance approval of bridges.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Advance approval of bridges. 115... BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES § 115.70 Advance approval of bridges. (a) The General Bridge Act of 1946 requires the approval of the location and plans of bridges prior...

Numerical analysis of dynamic response of vehicle–bridge coupled system on long-span continuous girder bridge

Directory of Open Access Journals (Sweden)

Lipeng An

2016-07-01

Full Text Available To systematically study the vehicle–bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle–bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the “set-in-right-position” rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long-span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the “general code for design of highway bridges and culverts (China”. The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle–bridge system.

Bridge Scour Technology Transfer

Science.gov (United States)

2018-01-24

Scour and flooding are the leading causes of bridge failures in the United States and therefore should be monitored. New applications of tools and technologies are being developed, tested, and implemented to reduce bridge scour risk. The National Coo...

Revised Rules for Concrete Bridges

DEFF Research Database (Denmark)

Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.

This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

Synthesis and characterization of nickel(II), cobalt(II), copper(II), manganese(II), zinc(II), zirconium(IV), dioxouranium(VI) and dioxomolybdenum(VI) complexes of a new Schiff base derived from salicylaldehyde and 5-methylpyrazole-3-carbohydrazide

International Nuclear Information System (INIS)

Syamal, A.; Maurya, M.R.

1986-01-01

Synthesis of a new Schiff base derived from salicylaldehyde and 5-methylpyrazole-3-carbohydrazide, and its coordination compounds with nickel(II), cobalt(II), copper(II), manganese(II), zinc(II), zirconium(IV), dioxouranium(VI) and dioxomolybdenum(VI) are described. The ligand and the complexes have been characterized on the basis of analytical, conductance, molecular weight, i.r., electronic and n.m.r. spectra and magnetic susceptibility measurements. The stoichiometries of the complexes are represented as NiL . 3H 2 O, CoL . 2H 2 O, CuL, MnL . 2H 2 O, ZnL . H 2 O, Zr(OH) 2 (LH) 2 , Zr(OH) 2 L . 2MeOH, UO 2 L . MeOH and MoO 2 L . MeOH (where LH 2 =Schiff base). The copper(II) complex shows a subnormal magnetic moment due to antiferromagnetic exchange interaction while the nickel(II), cobalt(II) and manganese(II) complexes show normal magnetic moments at room temperature. The i.r. and n.m.r. spectral studies show that the Schiff base behaves as a dibasic and tridentate ligand coordinating through the deprotonated phenolic oxygen, enolic oxygen and azomethine nitrogen. (orig.)

The stories of two bridges in Ghana

DEFF Research Database (Denmark)

Andreasen, Jørgen

2004-01-01

Public participation in bridge building was promoted by un habitat in the village of Mankrong. The neighbouring village did not participate in the construction of their bridge. The first flooding washed the second bridge down while the "participative bridge" stood up....

Bridging the Gap

DEFF Research Database (Denmark)

Dahlberg, Rasmus

2016-01-01

The fixed link between Denmark and Sweden connects two busy cities and a large international airport with many of its travelers and employees. 18,000 vehicles and 160 passenger trains transport each day more than 70,000 people across the combined road and rail Øresund Bridge and through the Øresu...... in its final report to the Danish and Swedish transport authorities while drawing upon experiences from two recent comparable cases of infrastructure disruptions: The Champlain Bridge (2009) and the Forth Road Bridge (2015).......The fixed link between Denmark and Sweden connects two busy cities and a large international airport with many of its travelers and employees. 18,000 vehicles and 160 passenger trains transport each day more than 70,000 people across the combined road and rail Øresund Bridge and through the Øresund...... Tunnel, approximately 25,000 of them critical to the regional work market. Even though the risk analysis states that the likelihood of a long-term closure (100C days) is very low Danish and Swedish transport authorities have demanded that the infrastructure operator conducts a survey of the preparedness...

49 CFR 236.766 - Locking, movable bridge.

Science.gov (United States)

2010-10-01

... 49 Transportation 4 2010-10-01 2010-10-01 false Locking, movable bridge. 236.766 Section 236.766... Locking, movable bridge. The rail locks, bridge locks, bolt locks, circuit controllers, and electric locks used in providing interlocking protection at a movable bridge. ...

Dynamic assessment of bridge deck performance considering realistic bridge-traffic interaction : research brief

Science.gov (United States)

2017-09-01

This study is to develop simulation methodology to conduct the dynamic assessment of bridge deck performance subjected to traffic. Concrete bridge decks are exposed to daily traffic loads and may experience some surface cracking caused by excessive s...

Development of a precast bridge deck overhang system for the rock creek bridge.

Science.gov (United States)

2008-12-01

Precast, prestressed panels are commonly used at interior beams for bridges in Texas. The use of these : panels provides ease of construction, sufficient capacity, and good economy for the construction of : bridges in Texas. Current practice for the ...

Field performance of timber bridges. 13, Mohawk Canal stress-laminated bridge

Science.gov (United States)

P. D. Hilbrich Lee; X. Lauderdale

The Mohawk Canal bridge was constructed in August 1994, just outside Roll, Arizona. It is a simple-span, double-lane, stress-laminated deck superstructure, approximately 6.4 m (21 ft) long and 10.4 m (34 ft) wide and constructed with Combination 16F-V3 Douglas Fir glued-laminated timber beam laminations. The performance of the bridge was monitored continuously for 2...

Development of inspection robots for bridge cables.

Science.gov (United States)

Yun, Hae-Bum; Kim, Se-Hoon; Wu, Liuliu; Lee, Jong-Jae

2013-01-01

This paper presents the bridge cable inspection robot developed in Korea. Two types of the cable inspection robots were developed for cable-suspension bridges and cable-stayed bridge. The design of the robot system and performance of the NDT techniques associated with the cable inspection robot are discussed. A review on recent advances in emerging robot-based inspection technologies for bridge cables and current bridge cable inspection methods is also presented.

Horizontal bridges in polar dielectric liquids

Energy Technology Data Exchange (ETDEWEB)

Woisetschlaeger, Jakob [Graz University of Technology, Experimental Turbomachinery Research and Optical Measurement Group, Institute for Thermal Turbomachinery and Machine Dynamics, Graz (Austria); Wexler, Adam D.; Fuchs, Elmar C. [Wetsus, Center of Excellence for Sustainable Water Technology, Leeuwarden (Netherlands); Holler, Gert [Graz University of Technology, Institute of Electrical Measurement and Measurement Signal Processing, Graz (Austria); Eisenhut, Mathias [Graz University of Technology, Institute of Analytical Chemistry and Food Chemistry, Graz (Austria); Gatterer, Karl [Graz University of Technology, Institute of Physical and Theoretical Chemistry, Graz (Austria)

2012-01-15

When a high-voltage direct-current is applied to two beakers filled with polar liquid dielectrica like water or methanol, a horizontal bridge forms between the two beakers. By repeating a version of Pellat's experiment, it is shown that a horizontal bridge is stable by the action of electrohydrodynamic pressure. Thus, the static and dynamic properties of the phenomenon called a 'floating water bridge' can be explained by the gradient of Maxwell pressure, replenishing the liquid within the bridge against any drainage mechanism. It is also shown that a number of liquids can form stable and long horizontal bridges. The stability of such a connection, and the asymmetry in mass flow through such bridges caused by the formation of ion clouds in the vicinity of the electrodes, is also discussed by two further experiments. (orig.)

Lean Construction Applications for Bridge Inspection

Science.gov (United States)

2017-10-01

Lean philosophy was used to analyze the efficiency of bridge inspection. Emphasis was put on identifying activities that add value to the final output, an owner approved bridge inspection report. 26 bridge inspections were shadowed. Time spent on bri...

Spread prestressed concrete slab beam bridges.

Science.gov (United States)

2015-04-01

TxDOT uses prestressed slab beam bridges for short-span bridges ranging from approximately 3050 ft in : length. These bridges have precast, pretensioned slab beams placed immediately adjacent to one another : with a cast-in-place slab made composi...

Crystal structure of di-μ-aqua-μ-(pyrazine N,N′-dioxide-κ2O:O-bis(diaquasodium tetraphenylborate dihydrate pyrazine N,N′-dioxide monosolvate

Directory of Open Access Journals (Sweden)

Elaine P. Boron

2015-12-01

Full Text Available The search for novel lanthanide coordination networks using pyrazine N,N′-dioxide (pzdo, C4H4N2O2 as a structure-directing unit, led to the synthesis and the structure determination of the title compound, [Na2(C4H4N2O2(H2O6][B(C6H54]2·C4H4N2O2·2H2O. The crystal structure is comprised of discrete [{Na(H2O2}2(μ-H2O2(μ-pzdo]2+ cations and tetraphenylborate anions, as well as pzdo and H2O solvent molecules. The dinuclear cation is located about a twofold rotation axis, and the symmetry-related NaI atoms display a distorted square-pyramidal coordination sphere defined by two O atoms of terminal water ligands, two O atoms of bridging water ligands and one O atom of a bridging pzdo ligand. In the crystal, O—H...O hydrogen bonds link the dinuclear cation and solvent pzdo molecules (point-group symmetry -1 into rectangular grid-like layers parallel to the bc plane. Additional C—H...O, O—H...O, C—H...π and O—H...π interactions link the anion and solvent water molecules to the layers. The layers are further linked into a three-dimensional network through a combination of C—H...π and O—H...π hydrogen bonds involving the tetraphenylborate anion.

Hydrodynamic forces on inundated bridge decks

Science.gov (United States)

2009-05-01

The hydrodynamic forces experienced by an inundated bridge deck have great importance in the design of bridges. Specifically, the drag force, lift force, and the moment acting on the bridge deck under various levels of inundation and a range of flow ...

Development of Inspection Robots for Bridge Cables

Directory of Open Access Journals (Sweden)

Hae-Bum Yun

2013-01-01

Full Text Available This paper presents the bridge cable inspection robot developed in Korea. Two types of the cable inspection robots were developed for cable-suspension bridges and cable-stayed bridge. The design of the robot system and performance of the NDT techniques associated with the cable inspection robot are discussed. A review on recent advances in emerging robot-based inspection technologies for bridge cables and current bridge cable inspection methods is also presented.

Design and construction of Chiburiko Bridge (stress ribbon bridge). Chiburiko bashi (tsurishoban kyo) no sekkei to seko

Energy Technology Data Exchange (ETDEWEB)

Kamisakoda, K; Tokuyama, S; Sano, K; Onuma, K [Kashima Corp., Tokyo (Japan)

1992-07-30

Chiburiko Bridge lies across Chiburiko which is a lake for agricultural water, and is used by people, carts and cars for administration. It is a stressed-ribbon bridge with the road surface made with concrete covered bands of cables stretched between abutments, and is the first highway bridge in Japan. A report is made on the plan and construction of the bridge. Integration of the precast slab with the cast-in-place concrete as well as mutual integration of the precast slabs are validated by the use of a reproduced model of a part of the bridge. Floor slabs are suspended by cables, and can be constructed with no form nor support by integrating cast-in-place concrete with the precast slabs on mutually joined precast slabs. It has been said that the stressed-ribbon bridge has a structure suitable for long span bridges because it has a simple structure. Studies, however, seems to be necessary on the impact caused by running of vehicles and on the wind resisting stability. 3 refs., 17 figs., 2 tabs.

The South Carolina bridge-scour envelope curves

Science.gov (United States)

Benedict, Stephen T.; Feaster, Toby D.; Caldwell, Andral W.

2016-09-30

The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, conducted a series of three field investigations to evaluate historical, riverine bridge scour in the Piedmont and Coastal Plain regions of South Carolina. These investigations included data collected at 231 riverine bridges, which lead to the development of bridge-scour envelope curves for clear-water and live-bed components of scour. The application and limitations of the South Carolina bridge-scour envelope curves were documented in four reports, each report addressing selected components of bridge scour. The current investigation (2016) synthesizes the findings of these previous reports into a guidance manual providing an integrated procedure for applying the envelope curves. Additionally, the investigation provides limited verification for selected bridge-scour envelope curves by comparing them to field data collected outside of South Carolina from previously published sources. Although the bridge-scour envelope curves have limitations, they are useful supplementary tools for assessing the potential for scour at riverine bridges in South Carolina.

Assessment of structural condition of Libeň Bridge

Directory of Open Access Journals (Sweden)

Kněž Petr

2017-01-01

Full Text Available The paper presents diagnostic and load tests of the Inundation bridge which is part of a group of bridges called The Libeň bridge group in Prague. The Libeň bridge group consists of two arched and several framed bridges spanning the Vltava river. One of the vaulted bridges consists of 5 arches and the other vaulted bridge (called Inundation bridge consists of only one arch. Arched bridges are extraordinary structures with both technical and historical value. Since the inundation bridge has the largest arch of whole group, it was selected for testing purposes. The bridge is assembled with three-hinged arch made of concrete. The hinges are made of reinforced concrete and lead contact slabs. Detailed measurements of geometry and material properties were made on the bridge. Based on these measurements a computer model was created to verify the behavior of the structure. Both static and dynamic calculations were performed. Measurements of dynamic characteristics were made during normal operation and with hydraulic vibration exciter. This article will focus on comparing the results of dynamic calculation of the modeled structure and properties measured on real structure excited by hydraulic vibration exciter.

Students design composite bridges

NARCIS (Netherlands)

Stark, J.W.B.; Galjaard, J.C.; Brekelmans, J.W.P.M.

1999-01-01

The paper gives an overview of recent research on steel-concrete composite bridge design by students of Delft University of Technology doing their master's thesis. Primary objective of this research was to find possibilities for application of steel-concrete composite bridges in the Netherlands,

33 CFR 118.140 - Painting bridge piers.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Painting bridge piers. 118.140 Section 118.140 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.140 Painting bridge piers. The District Commander may require...

Superconductivity in small metal bridges

International Nuclear Information System (INIS)

Hannah, E.C.

1975-01-01

Josephson effects in weaklinks are discussed for low and high frequency regimes using simple perturbation techniques. It is proven that no measurement of the supercurrent dependence upon frequency above the Riedel peak frequency can be made using rf sources whose frequencies are below the Riedel peak. Thus the bulk of work done in the field on the high frequency structure of the Josephson current is shown to be invalid. Metal bridges shorter than a newly defined temperature independent length for superconductors, l/sub PHONON/, are proven to be identical in their Josephson current behavior to tunneling junctions. The BCS gap equation is generalized to include voltage gradient effects on pairs within the bridge. The oscillation frequency for long bridges (l/sub BRIDGE/ greater than l/sub PHONON/) is shown to be limited to less than 10'' Hz. An experimental test of the new voltage dependent gap is made as well as tests of the pair reforming time of bridges

Bridge scour monitoring technologies : development of evaluation and selection protocols for application on river bridges in Minnesota.

Science.gov (United States)

2010-03-01

Bridge failure or loss of structural integrity can result from scour of riverbed sediment near bridge abutments or : piers during high-flow events in rivers. In the past 20 years, several methods of monitoring bridge scour have been : developed spann...

Synthesis, Characterization and Antimicrobial Studies of a New Mannich Base N-[Morpholino(phenylmethyl]acetamide and Its Cobalt(II, Nickel(II and Copper(II Metal Complexes

Directory of Open Access Journals (Sweden)

L. Muruganandam

2012-01-01

Full Text Available A new Mannich base N-[morpholino(phenylmethyl]acetamide (MBA, was synthesized and characterized by spectral studies. Chelates of MBA with cobalt(II, nickel(II and copper(II ions were prepared and characterized by elemental analyses, IR and UV spectral studies. MBA was found to act as a bidentate ligand, bonding through the carbonyl oxygen of acetamide group and CNC nitrogen of morpholine moiety in all the complexes. Based on the magnetic moment values and UV-Visible spectral data, tetracoordinate geometry for nitrato complexes and hexacoordinate geometry for sulphato complexes were assigned. The antimicrobial studies show that the Co(II nitrato complex is more active than the other complexes.

33 CFR 118.90 - Bridges crossing channel obliquely.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bridges crossing channel obliquely. 118.90 Section 118.90 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.90 Bridges crossing channel obliquely. Bridges...

Cambios esqueléticos, faciales y dentoalveolares producidos por el tratamiento con placas de acetato y elásticos de clase III en pacientes con mesiorrelación esquelética y dental en dentición decidua o mixta temprana

OpenAIRE

Espinal Botero, Gabriel Emilio; Betancur Pérez, John Jairo; Blandón Uribe, Ana María; Ortiz Burgos, Paola Alejandra

2011-01-01

Introducción: el propósito fue establecer los cambios clínicos y radiográficos con el uso durante un año de placas de acetato bimaxilares con elásticos de clase III para el tratamiento de la clase III esquelética en pacientes con dentición decidua o mixta temprana. Métodos: se hizo un estudio clínico prospectivo cuasi-experimental en 26 sujetos entre tres y nueve años. Se tomaron radiografías cefálicas laterales y modelos de estudio al inicio, a los seis meses y al año de tratamiento, se eval...

33 CFR 118.100 - Retroreflective panels on bridge piers.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Retroreflective panels on bridge... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.100 Retroreflective panels on bridge piers. The... 12 inches square. (c) To mark bridge piers or channel sides on bridges not required to have bridge...

Concrete-Filled Steel Tube Arch Bridges in China

Directory of Open Access Journals (Sweden)

Jielian Zheng

2018-02-01

Full Text Available In the past 20 years, great progress has been achieved in China in the construction of concrete-filled steel tube (CFST arch bridges and concrete arch bridges with a CFST skeleton. The span of these bridges has been increasing rapidly, which is rare in the history of bridge development. The large-scale construction of expressways and high-speed railways demands the development of long-span arch bridges, and advances in design and construction techniques have made it possible to construct such bridges. In the present study, the current status, development, and major innovative technologies of CFST arch bridges and concrete arch bridges with a CFST skeleton in China are elaborated. This paper covers the key construction technologies of CFST arch bridges, such as the design, manufacture, and installation of steel tube arch trusses, the preparation and pouring of in-tube concrete, and the construction of the world’s longest CFST arch bridge—the First Hejiang Yangtze River Bridge. The main construction technologies of reinforced concrete arch bridges are also presented, which include cable-stayed fastening-hanging cantilever assembly, adjusting the load by means of stay cables, surrounding the concrete for arch rib pouring, and so forth. In addition, the construction of two CFST skeleton concrete arch bridges—the Guangxi Yongning Yong River Bridge and the Yunnan–Guangxi Railway Nanpan River Bridge—is discussed. CFST arch bridges in China have already gained a world-leading position; with the continuous innovation of key technologies, China will become the new leader in promoting the development of arch bridges. Keywords: Concrete-filled steel tube (CFST arch bridge, Steel-reinforced concrete arch bridge, Cable-stayed fastening-hanging cantilever assembly, Vacuum-assisted pouring in-tube concrete, Adjusting load by stay cables

Reliability Modeling of Double Beam Bridge Crane

Science.gov (United States)

Han, Zhu; Tong, Yifei; Luan, Jiahui; Xiangdong, Li

2018-05-01

This paper briefly described the structure of double beam bridge crane and the basic parameters of double beam bridge crane are defined. According to the structure and system division of double beam bridge crane, the reliability architecture of double beam bridge crane system is proposed, and the reliability mathematical model is constructed.

LIGHT BRIDGE IN A DEVELOPING ACTIVE REGION. I. OBSERVATION OF LIGHT BRIDGE AND ITS DYNAMIC ACTIVITY PHENOMENA

International Nuclear Information System (INIS)

Toriumi, Shin; Katsukawa, Yukio; Cheung, Mark C. M.

2015-01-01

Light bridges, the bright structures that divide the umbra of sunspots and pores into smaller pieces, are known to produce a wide variety of activity events in solar active regions (ARs). It is also known that the light bridges appear in the assembling process of nascent sunspots. The ultimate goal of this series of papers is to reveal the nature of light bridges in developing ARs and the occurrence of activity events associated with the light bridge structures from both observational and numerical approaches. In this first paper, exploiting the observational data obtained by Hinode, the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory, we investigate the detailed structure of the light bridge in NOAA AR 11974 and its dynamic activity phenomena. As a result, we find that the light bridge has a weak, horizontal magnetic field, which is transported from the interior by a large-scale convective upflow and is surrounded by strong, vertical fields of adjacent pores. In the chromosphere above the bridge, a transient brightening occurs repeatedly and intermittently, followed by a recurrent dark surge ejection into higher altitudes. Our analysis indicates that the brightening is the plasma heating due to magnetic reconnection at lower altitudes, while the dark surge is the cool, dense plasma ejected from the reconnection region. From the observational results, we conclude that the dynamic activity observed in a light bridge structure such as chromospheric brightenings and dark surge ejections are driven by magnetoconvective evolution within the light bridge and its interaction with the surrounding magnetic fields

LIGHT BRIDGE IN A DEVELOPING ACTIVE REGION. I. OBSERVATION OF LIGHT BRIDGE AND ITS DYNAMIC ACTIVITY PHENOMENA

Energy Technology Data Exchange (ETDEWEB)

Toriumi, Shin; Katsukawa, Yukio [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Cheung, Mark C. M., E-mail: shin.toriumi@nao.ac.jp [Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover Street, Building/252, Palo Alto, CA 94304 (United States)

2015-10-01

Light bridges, the bright structures that divide the umbra of sunspots and pores into smaller pieces, are known to produce a wide variety of activity events in solar active regions (ARs). It is also known that the light bridges appear in the assembling process of nascent sunspots. The ultimate goal of this series of papers is to reveal the nature of light bridges in developing ARs and the occurrence of activity events associated with the light bridge structures from both observational and numerical approaches. In this first paper, exploiting the observational data obtained by Hinode, the Interface Region Imaging Spectrograph, and the Solar Dynamics Observatory, we investigate the detailed structure of the light bridge in NOAA AR 11974 and its dynamic activity phenomena. As a result, we find that the light bridge has a weak, horizontal magnetic field, which is transported from the interior by a large-scale convective upflow and is surrounded by strong, vertical fields of adjacent pores. In the chromosphere above the bridge, a transient brightening occurs repeatedly and intermittently, followed by a recurrent dark surge ejection into higher altitudes. Our analysis indicates that the brightening is the plasma heating due to magnetic reconnection at lower altitudes, while the dark surge is the cool, dense plasma ejected from the reconnection region. From the observational results, we conclude that the dynamic activity observed in a light bridge structure such as chromospheric brightenings and dark surge ejections are driven by magnetoconvective evolution within the light bridge and its interaction with the surrounding magnetic fields.

[Mo2(CN)11]:5- A detailed description of ligand-field spectra and magnetic properties by first-principles calculations.

Science.gov (United States)

Hendrickx, Marc F A; Clima, S; Chibotaru, L F; Ceulemans, A

2005-10-06

An ab initio multiconfigurational approach has been used to calculate the ligand-field spectrum and magnetic properties of the title cyano-bridged dinuclear molybdenum complex. The rather large magnetic coupling parameter J for a single cyano bridge, as derived experimentally for this complex by susceptibility measurements, is confirmed to a high degree of accuracy by our CASPT2 calculations. Its electronic structure is rationalized in terms of spin-spin coupling between the two constituent hexacyano-monomolybdate complexes. An in-depth analysis on the basis of Anderson's kinetic exchange theory provides a qualitative picture of the calculated CASSCF antiferromagnetic ground-state eigenvector in the Mo dimer. Dynamic electron correlations as incorporated into our first-principles calculations by means of the CASPT2 method are essential to obtain quantitative agreement between theory and experiment.

Bridge Aesthetics and Structural Honesty

DEFF Research Database (Denmark)

Gimsing, Niels Jørgen

1999-01-01

In bridges the overall form must be chosen with due respect to the transmission of forces if efficient structures shall be created, The design must therefore be governed by experienced structural engineers - in some cases assisted by aesthetic advisers on specific issues. Some basic requirements...... decisive for choosing the form of trusses, arches and cable-stayed bridges are outlined, and several examples show bridges designed without giving priority to the structural aspects....

Strategies For The Replacement Of Historic Bridge Guardrails

OpenAIRE

Clauss, Adam J.

2014-01-01

Bridges that are designated historic present a special challenge to bridge engineers whenever rehabilitation work or improvements are made to the bridges. Federal and state laws protect historically significant bridges, and railings on these bridges can be subject to protection because of the role they play in aesthetics. Unfortunately, original railings on historic bridges do not typically meet current crash-test requirements and typically do not meet current standards for railing height and...

When, where and how the bridge breaks: anaphase bridge breakage plays a crucial role in gene amplification and HSR generation

International Nuclear Information System (INIS)

Shimizu, Noriaki; Shingaki, Kenta; Kaneko-Sasaguri, Yukiko; Hashizume, Toshihiko; Kanda, Teru

2005-01-01

Amplified genes are frequently localized on extrachromosomal double minutes (DMs) or in chromosomal homogenously staining regions (HSRs). We previously showed that a plasmid bearing a mammalian replication initiation region could efficiently generate DMs and HSRs after transfection into human tumor cell lines. The Breakage-Fusion-Bridge (BFB) cycle model, a classical model that explains how HSRs form, could also be used to explain how the transfected plasmids generate HSRs. The BFB cycle model involves anaphase bridge formation due to the presence of dicentric chromosomes, followed by the breakage of the bridge. In this study, we used our plasmid-based model system to analyze how anaphase bridges break during mitosis. Dual-color fluorescence in situ hybridization analyses revealed that anaphase bridges were most frequently severed in their middle irrespective of their lengths, which suggests that a structurally fragile site exists in the middle of the anaphase bridge. Breakage of the chromosomal bridges occurred prior to nuclear membrane reformation and the completion of cytokinesis, which indicates that mechanical tension rather than cytokinesis is primarily responsible for severing anaphase bridges. Time-lapse observation of living cells revealed that the bridges rapidly shrink after being severed. If HSR length was extended too far, the bridge could no longer be resolved and became tangled depending on the tension. The unbroken bridge appeared to inhibit the completion of cytokinesis. These observations strongly suggest that anaphase bridges are highly elastic and that the length of the spindle axis determines the maximal HSR length

A novel dumbbell-like polyoxometalate assembled of copper(II)-disubstituted monovacant keggin polyoxoanions with a tetranuclear copper cluster.

Science.gov (United States)

Miao, Hao; Xu, Xiao; Ju, Wei-Wei; Wan, Hong-Xiang; Zhang, Yu; Zhu, Dun-Ru; Xu, Yan

2014-03-17

A dimeric Keggin polyoxometalate, [Cu(bpy)(μ2-OH)]4[(H2O)(bpy)2HPW11Cu2O39]2·2CH3CH2OH·10H2O (1), constructed from two dicopper(II)-substituted monovacant Keggin polyoxoanions bridged by a Cu4 cluster, has been hydrothermally synthesized. Magnetic analysis indicates predominantly an antiferromagnetic interaction between copper(II) centers. Compound 1 also shows very high catalytic activity for the esterification of phosphoric acid with equimolar lauryl alcohol to monoalkyl phosphate ester.

33 CFR 118.70 - Lights on swing bridges.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on swing bridges. 118.70 Section 118.70 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.70 Lights on swing bridges. (a) Swing span lights on through bridges. Each...

33 CFR 118.65 - Lights on fixed bridges.

Science.gov (United States)

2010-07-01

... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on fixed bridges. 118.65 Section 118.65 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.65 Lights on fixed bridges. (a) Each fixed bridge span over a navigable...

23 CFR 650.409 - Evaluation of bridge inventory.

Science.gov (United States)

2010-04-01

... 23 Highways 1 2010-04-01 2010-04-01 false Evaluation of bridge inventory. 650.409 Section 650.409... Evaluation of bridge inventory. (a) Sufficiency rating of bridges. Upon receipt and evaluation of the bridge inventory, a sufficiency rating will be assigned to each bridge by the Secretary in accordance with the...

ACÚMULO DE CÁDMIO POR Saccharomyces cerevisiae EM CALDO DE CANA-DE-AÇÚCAR CONTAMINADO COM ACETATO DE CÁDMIO

Directory of Open Access Journals (Sweden)

Mariano-da-Silva Samuel

1999-01-01

Full Text Available O presente trabalho visou estudar o acúmulo de cádmio (Cd por Saccharomyces cerevisiae, fermentando mosto de caldo de cana-de-açúcar com contaminações controladas, em níveis sub-tóxicos do citado metal. As condições de fermentação foram similares às reinantes na produção industrial de etanol. O mosto, não esterelizado, continha 12% de açúcares redutores totais (ART e pH 4,5. Para a contaminação controlada empregou-se acetato de cádmio em quatro níveis de contaminações (0,5; 1,0; 2,0 e 5,0 mg Cd kg-1 mosto. A inoculação do mosto foi executada com fermento de panificação (10% p/p. Após a fermentação (4 horas foram determinados, porcentagem de fermento no vinho centrifugado e teor alcoólico do mesmo. Na levedura separada foram determinados peso úmido, matéria seca, proteína bruta e teores de cádmio por espectrofotometria de absorção atômica. Em todos os níveis de contaminação estudados houve acúmulo de Cd pela levedura.

Effects of Electrolyte on Floating Water Bridge

OpenAIRE

Hideo Nishiumi; Fumitaka Honda

2009-01-01

Fuchs found phenomena that when high voltage is applied to deionized water filled in two contacted beakers, a floating water bridge forms spontaneously. In this paper, we examined flow direction of water bridge and what effects the addition of electrolytes such as NaCl, NaOH, and N H 4 C l to the floating water bridge would give. We found that ionization degree reduced the length of water bridge though insoluble electrolyte A l 2 O 3 had no effect on the length of water bridge.

A data management infrastructure for bridge monitoring

Science.gov (United States)

Jeong, Seongwoon; Byun, Jaewook; Kim, Daeyoung; Sohn, Hoon; Bae, In Hwan; Law, Kincho H.

2015-04-01

This paper discusses a data management infrastructure framework for bridge monitoring applications. As sensor technologies mature and become economically affordable, their deployment for bridge monitoring will continue to grow. Data management becomes a critical issue not only for storing the sensor data but also for integrating with the bridge model to support other functions, such as management, maintenance and inspection. The focus of this study is on the effective data management of bridge information and sensor data, which is crucial to structural health monitoring and life cycle management of bridge structures. We review the state-of-the-art of bridge information modeling and sensor data management, and propose a data management framework for bridge monitoring based on NoSQL database technologies that have been shown useful in handling high volume, time-series data and to flexibly deal with unstructured data schema. Specifically, Apache Cassandra and Mongo DB are deployed for the prototype implementation of the framework. This paper describes the database design for an XML-based Bridge Information Modeling (BrIM) schema, and the representation of sensor data using Sensor Model Language (SensorML). The proposed prototype data management framework is validated using data collected from the Yeongjong Bridge in Incheon, Korea.

Railway bridge monitoring during construction and sliding

Science.gov (United States)

Inaudi, Daniele; Casanova, Nicoletta; Kronenberg, Pascal; Vurpillot, Samuel

1997-05-01

The Moesa railway bridge is a composite steel concrete bridge on three spans of 30 m each. The 50 cm thick concrete deck is supported on the lower flanges of two continuous, 2.7 m high I-beams. The bridge has been constructed alongside an old metallic bridge. After demolishing this one, the new bridge has been slid for 5 m by 4 hydraulic jacks and positioned on the refurbished piles of the old bridge. About 30 fiber optic, low-coherence sensors were imbedded in the concrete deck to monitor its deformations during concrete setting and shrinkage, as well as during the bridge sliding phase. In the days following concrete pour it was possible to follow its thermal expansion due to the exothermic setting reaction and the following thermal and during shrinkage. The deformations induced by the additional load produced by the successive concreting phases were also observed. During the bridge push, which extended over six hours, the embedded and surface mounted sensors allowed the monitoring of the curvature variations in the horizontal plane due to the slightly uneven progression of the jacks. Excessive curvature and the resulting cracking of concrete could be ruled out by these measurements. It was also possible to observe the bridge elongation under the heating action of the sun.

On the effect of nuclear bridge modes on donor-acceptor electronic coupling in donor-bridge-acceptor molecules

International Nuclear Information System (INIS)

Davis, Daly; Toroker, Maytal Caspary; Speiser, Shammai; Peskin, Uri

2009-01-01

We report a theoretical study of intra-molecular electronic coupling in a symmetric DBA (donor-bridge-acceptor) complex, in which a donor electronic site is coupled to an acceptor site by way of intervening orbitals of a molecular bridge unit. In the off-resonant (deep tunneling) regime of electronic transport, the lowest unoccupied molecular orbitals (MO's) of the DBA system are split into distinguishable donor/acceptor and bridge orbitals. The effect of geometrical changes at the bridge on the donor/acceptor electronic energy manifold is studied for local stretching and bending modes. It is demonstrated that the energy splitting in the manifold of donor/acceptor unoccupied MOs changes in response to such changes, as assumed in simple McConnell-type models. Limitations of the simple models are revealed where the electronic charging of the bridge orbitals correlates with increasing donor/acceptor orbital energy splitting only for stretching but not for bending bridge modes.

IceBridge Mission Flight Reports

Data.gov (United States)

National Aeronautics and Space Administration — The IceBridge Mission Flight Reports data set contains flight reports from NASA Operation IceBridge Greenland, Arctic, Antarctic, and Alaska missions. Flight reports...

Bridges analysis, design, structural health monitoring, and rehabilitation

CERN Document Server

Bakht, Baidar

2015-01-01

This book offers a valuable guide for practicing bridge engineers and graduate students in structural engineering; its main purpose is to present the latest concepts in bridge engineering in fairly easy-to-follow terms. The book provides details of easy-to-use computer programs for: ·      Analysing slab-on-girder bridges for live load distribution. ·      Analysing slab and other solid bridge components for live load distribution. ·      Analysing and designing concrete deck slab overhangs of girder bridges under vehicular loads. ·      Determining the failure loads of concrete deck slabs of girder bridges under concentrated wheel loads. In addition, the book includes extensive chapters dealing with the design of wood bridges and soil-steel bridges. Further, a unique chapter on structural health monitoring (SHM) will help bridge engineers determine the actual load carrying capacities of bridges, as opposed to their perceived analytical capacities. The chapter addressing structures...

Virtual Bridge Design Challenge

Science.gov (United States)

Mitts, Charles R.

2013-01-01

This design/problem-solving activity challenges students to design a replacement bridge for one that has been designated as either structurally deficient or functionally obsolete. The Aycock MS Technology/STEM Magnet Program Virtual Bridge Design Challenge is an authentic introduction to the engineering design process. It is a socially relevant…

The floating water bridge

International Nuclear Information System (INIS)

Fuchs, Elmar C; Woisetschlaeger, Jakob; Gatterer, Karl; Maier, Eugen; Pecnik, Rene; Holler, Gert; Eisenkoelbl, Helmut

2007-01-01

When high voltage is applied to distilled water filled in two glass beakers which are in contact, a stable water connection forms spontaneously, giving the impression of a floating water bridge. A detailed experimental analysis reveals static and dynamic structures as well as heat and mass transfer through this bridge

MODERN ASPECTS OF BRIDGES MONITORING

Directory of Open Access Journals (Sweden)

M. I. Kazakevych

2007-12-01

Full Text Available The major concepts of the elaboration and realization of the bridge construction monitoring systemic approach are presented in this paper. The main peculiarity of the bridge monitoring modern aspect is pointed out here, namely, the transition from the demands of providing the reliability to the demands of providing the whole complex of the structure consumer qualities. The criteria of diagnostics of the bridge exploitation reliability as the fundamental aim of monitoring are formulated here.

75 FR 62181 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation

Science.gov (United States)

2010-10-07

... INFORMATION CONTACT: Ms. Ann Shemaka, Office of Bridge Technology, HIBT-30, (202) 366-1575, or Mr. Thomas Everett, Office of Bridge Technology, HIBT-30, (202) 366-4675, Federal Highway Administration, 1200 New... is categorized by the following material types, which are identified in the NBI: steel, concrete, pre...

77 FR 53251 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation

Science.gov (United States)

2012-08-31

... INFORMATION CONTACT: Ms. Ann Shemaka, Office of Bridge Technology, (202) 366-1575, or via email at [email protected] or Mr. Thomas Everett, Office of Bridge Technology, (202) 366-4675, or via email at thomas... the NBI: steel, concrete, pre-stressed concrete, and other. The category ``other'' includes wood...

76 FR 55160 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation

Science.gov (United States)

2011-09-06

... INFORMATION CONTACT: Ms. Ann Shemaka, Office of Bridge Technology, HIBT-30, (202) 366-1575, or Mr. Thomas Everett, Office of Bridge Technology, HIBT-30, (202) 366-4675, Federal Highway Administration, 1200 New... is categorized by the following material types, which are identified in the NBI: steel, concrete, pre...

Comparison of the Magnetic Anisotropy and Spin Relaxation Phenomenon of Dinuclear Terbium(III) Phthalocyaninato Single-Molecule Magnets Using the Geometric Spin Arrangement.

Science.gov (United States)

Morita, Takaumi; Damjanović, Marko; Katoh, Keiichi; Kitagawa, Yasutaka; Yasuda, Nobuhiro; Lan, Yanhua; Wernsdorfer, Wolfgang; Breedlove, Brian K; Enders, Markus; Yamashita, Masahiro

2018-02-28

Herein we report the synthesis and characterization of a dinuclear Tb III single-molecule magnet (SMM) with two [TbPc 2 ] 0 units connected via a fused-phthalocyaninato ligand. The stable and robust complex [(obPc)Tb(Fused-Pc)Tb(obPc)] (1) was characterized by using synchrotron radiation measurements and other spectroscopic techniques (ESI-MS, FT-IR, UV). The magnetic couplings between the Tb III ions and the two π radicals present in 1 were explored by means of density functional theory (DFT). Direct and alternating current magnetic susceptibility measurements were conducted on magnetically diluted and nondiluted samples of 1, indicating this compound to be an SMM with improved properties compared to those of the well-known [TbPc 2 ] -/0/+ and the axially symmetric dinuclear Tb III phthalocyaninato triple-decker complex (Tb 2 (obPc) 3 ). Assuming that the probability of quantum tunneling of the magnetization (QTM) occurring in one TbPc 2 unit is P QTM , the probability of QTM simultaneously occurring in 1 is P QTM 2 , meaning that QTM is effectively suppressed. Furthermore, nondiluted samples of 1 underwent slow magnetic relaxation times (τ ≈ 1000 s at 0.1 K), and the blocking temperature (T B ) was determined to be ca. 16 K with an energy barrier for spin reversal (U eff ) of 588 cm -1 (847 K) due to D 4d geometry and weak inter- and intramolecular magnetic interactions as an exchange bias (H bias ), reducing QTM. Four hyperfine steps were observed by micro-SQUID measurement. Furthermore, solution NMR measurements (one-dimensional, two-dimensional, and dynamic) were done on 1, which led to the determination of the high rotation barrier (83 ± 10 kJ/mol) of the obPc ligand. A comparison with previously reported Tb III triple-decker compounds shows that ambient temperature NMR measurements can indicate improvements in the design of coordination environments for SMMs. A large U eff causes strong uniaxial magnetic anisotropy in 1, leading to a χ ax value (1.39 �

Prosthetic rehabilitation using adhesive bridge and fixed-fixed bridge on the maxilla and telescopic crown overdenture on mandible

Directory of Open Access Journals (Sweden)

Indah Sulistiawaty

2016-12-01

Full Text Available Prosthetic rehabilitation is the rehabilitation process of masticatory and esthetics function for patients missing teeth and alveolar bone by means of manufacture and installation of dentures. The prosthetic rehabilitation commonly used include denture adhesive bridge, fixed-fixed bridge, as well as telescopic overdenture. Adhesive bridge is bridge denture consisting of single pontic and two retainer wings attached to the abutment using cement or resin. Fixed-fixed bridge is a bridge denture with rigid connectors on both ends of the pontics, whereas the telescopic crown Overdenture is a removable denture that uses linked precision on the original tooth in the form of primary coping on abutment and secondary coping on the denture. To expose the procedures of prosthetic rehabilitation using adhesive bridge and fixed-fixed bridge on the maxilla and telescopic crown Overdenture on mandible. Male patients aged 32 years came with complaints of difficulty to chew food because he had lost some teeth behind. In the maxilla, teeth are lost in the region of 15 and 16 performed by making the fixed-fixed bridge with abutment teeth 14 and 17. Loss of teeth in the region of 26, performed the manufacture of adhesive bridge with a box preparation on the occlusal 25 and 27. In the mandible, tooth loss in the region of 36,37,46, and 47 performed manufacture of telescopic crown Overdenture with primer coping on the teeth 35.38, 45, and 48 and the secondary coping on a metal frame. Prosthetic rehabilitation especially in the case of loss of back teeth is very important because with the denture patients can chew properly and maintain the stomatognathic system.

Remediation: Higher Education's Bridge to Nowhere

Science.gov (United States)

Complete College America, 2012

2012-01-01

The intentions were noble. It was hoped that remediation programs would be an academic bridge from poor high school preparation to college readiness. Sadly, remediation has become instead higher education's "Bridge to Nowhere." This broken remedial bridge is travelled by some 1.7 million beginning students each year, most of whom will…

Effects of Electrolyte on Floating Water Bridge

Directory of Open Access Journals (Sweden)

Hideo Nishiumi

2009-01-01

spontaneously. In this paper, we examined flow direction of water bridge and what effects the addition of electrolytes such as NaCl, NaOH, and NH4Cl to the floating water bridge would give. We found that ionization degree reduced the length of water bridge though insoluble electrolyte Al2O3 had no effect on the length of water bridge.

Elisa de captura com IgY para quantificação de acetato de lupeol em Vernonia scorpioides lam. Pers (asteraceae Capture IgY-elisa to quantify lupeol acetate in Vernonia scorpioides lam. Pers (asteraceae

Directory of Open Access Journals (Sweden)

Ronald Bastos Freire

2004-08-01

Full Text Available O presente experimento descreve, pela primeira vez, a elaboração de um ensaio imunoenzimático (ELISA de captura com anticorpos IgY para a detecção e quantificação de acetato de lupeol (LAc em Vernonia scorpioides Lam. Pers (Asteraceae. Anticorpos anti-LAc, obtidos partir do soro das aves e gemas de seus ovos, após imunização com o conjugado acetato de lupeol-cBSA, foram concentrados em coluna contendo LAc-BSA acoplado a sepharose. A eficácia da metodologia de detecção imunológica foi de 97%, com índices de sensibilidade e especificidade de 99% e 95%, respectivamente com limites de detecção do ensaio entre 0,02µg.g-1 (inferior e 10 µg.g-1 (superior. A robustez do método foi atestada pela sua elevada reprodutibilidade (entre 94,75% e 96,81%, e pelo baixo coeficiente de variação interna (4,22 ± 1,03% nas condições de execução descritas.For the first time, a yolk immunoglobulins-based immunenzymatic assay (capture IgY-ELISA was carried out to detect Lupeol acetate (LAc from Vernonia scorpioides Lam. Pers (Asteraceae. Antibodies (IgY against lupeol acetate (anti-LAc antibodies were raised in White Leghorn hens immunized with LAc conjugated to the bovine serum albumin (LAc-BSA. The anti-LAc antibodies were recovered by cleanup columns containing LAc-BSA coupled to sepharose. The capture IgY-ELISA efficacy was of 97% when the predictive indices of sensitivity and specificity were 99.0% and 95%, respectively. The lowest and highest detection limits were of 0.02µg g-1 and 10µg.g-1 of plant extract, respectively. The strength of this method was attested by its high reproducibility (between 94.75% and 96.81%, and a low internal variation (4.22 ± 1.03%, under the described conditions.

LIGHT BRIDGE IN A DEVELOPING ACTIVE REGION. II. NUMERICAL SIMULATION OF FLUX EMERGENCE AND LIGHT BRIDGE FORMATION

International Nuclear Information System (INIS)

Toriumi, Shin; Katsukawa, Yukio; Cheung, Mark C. M.

2015-01-01

Light bridges, the bright structure dividing umbrae in sunspot regions, show various activity events. In Paper I, we reported on an analysis of multi-wavelength observations of a light bridge in a developing active region (AR) and concluded that the activity events are caused by magnetic reconnection driven by magnetconvective evolution. The aim of this second paper is to investigate the detailed magnetic and velocity structures and the formation mechanism of light bridges. For this purpose, we analyze numerical simulation data from a radiative magnetohydrodynamics model of an emerging AR. We find that a weakly magnetized plasma upflow in the near-surface layers of the convection zone is entrained between the emerging magnetic bundles that appear as pores at the solar surface. This convective upflow continuously transports horizontal fields to the surface layer and creates a light bridge structure. Due to the magnetic shear between the horizontal fields of the bridge and the vertical fields of the ambient pores, an elongated cusp-shaped current layer is formed above the bridge, which may be favorable for magnetic reconnection. The striking correspondence between the observational results of Paper I and the numerical results of this paper provides a consistent physical picture of light bridges. The dynamic activity phenomena occur as a natural result of the bridge formation and its convective nature, which has much in common with those of umbral dots and penumbral filaments

Optimum Maintenance Strategies for Highway Bridges

DEFF Research Database (Denmark)

Frangopol, Dan M.; Thoft-Christensen, Palle; Das, Parag C.

As bridges become older and maintenance costs become higher, transportation agencies are facing challenges related to implementation of optimal bridge management programs based on life cycle cost considerations. A reliability-based approach is necessary to find optimal solutions based on minimum...... expected life-cycle costs or maximum life-cycle benefits. This is because many maintenance activities can be associated with significant costs, but their effects on bridge safety can be minor. In this paper, the program of an investigation on optimum maintenance strategies for different bridge types...... is described. The end result of this investigation will be a general reliability-based framework to be used by the UK Highways Agency in order to plan optimal strategies for the maintenance of its bridge network so as to optimize whole-life costs....

Investigation of Aerodynamic Interference between Twin Deck Bridges

Energy Technology Data Exchange (ETDEWEB)

Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC)

2016-05-01

Construction of a twin bridge can be a cost effective and minimally disruptive way to increase capacity when an existing bridge is not near the end of its service life. With ever growing vehicular traffic, when demand approaches the capacity of many existing roads and bridges. Remodeling a structure with an insufficient number of lanes can be a good solution in case of smaller and less busy bridges. Closing down or reducing traffic on crossings of greater importance for the construction period, however, can result in major delays and revenue loss for commerce and transportation as well as increasing the traffic load on alternate route bridges. Multiple-deck bridges may be the answer to this issue. A parallel deck can be built next to the existing one, without reducing the flow. Additionally, a new bridge can be designed as a twin or multi-deck structure. Several such structures have been built throughout the United States, among them: - The New NY Bridge Project - the Tappan Zee Hudson River Crossing, - SR-182 Columbia River Bridge, - The Thaddeus Kosciusko Bridge (I-87), - The Allegheny River Bridge, Pennsylvania, which carries I76, - Fred Hartman Bridge, TX, see Figure 1.2. With a growing number of double deck bridges, additional, more detailed, studies on the interaction of such bridge pairs in windy conditions appears appropriate. Aerodynamic interference effects should be examined to assure the aerodynamic stability of both bridges. There are many studies on aerodynamic response of single deck bridges, but the literature on double-deck structures is not extensive. The experimental results from wind tunnels are still limited in number, as a parametric study is required, they can be very time consuming. Literature review shows that some investigation of the effects of gap-width and angle of wind incidence has been done. Most of the CFD computational studies that have been done were limited to 2D simulations. Therefore, it is desirable to investigate twin decks

Efeitos do implante subdérmico de acetato de nomegestrol sobre o metabolismo de carboidratos, lipoproteínas séricas e função hepática The effects of nomegestrol acetate subdermal implant on carbohydrate metabolism, serum lipoproteins and on hepatic function

OpenAIRE

Ione Barbosa; Elsimar Coutinho; Célia Athayde; Oladapo Ladipo; Sven-Eric Olsson; Ulf Ulmsten

1998-01-01

Objetivos: avaliar variações de peso corporal, pressão arterial, glicemia em jejum, HbA1C, insulina, colesterol total, HDL-C, LDL-C, triglicérides, TGO, TGP, GGT e bilirrubina em mulheres usuárias de um implante único, subdérmico, de Silástico, contendo 55 mg (±10%) de acetato de nomegestrol, durante dois anos. Métodos: dezoito voluntárias saudáveis e em idade reprodutiva, que desejavam fazer uso de anticoncepcionais e não apresentavam contra-indicações para o uso de contracepção hormonal, pa...

Review of Energy Harvesters Utilizing Bridge Vibrations

Directory of Open Access Journals (Sweden)

Farid Ullah Khan

2016-01-01

Full Text Available For health monitoring of bridges, wireless acceleration sensor nodes (WASNs are normally used. In bridge environment, several forms of energy are available for operating WASNs that include wind, solar, acoustic, and vibration energy. However, only bridge vibration has the tendency to be utilized for embedded WASNs application in bridge structures. This paper reports on the recent advancements in the area of vibration energy harvesters (VEHs utilizing bridge oscillations. The bridge vibration is narrowband (1 to 40 Hz with low acceleration levels (0.01 to 3.8 g. For utilization of bridge vibration, electromagnetic based vibration energy harvesters (EM-VEHs and piezoelectric based vibration energy harvesters (PE-VEHs have been developed. The power generation of the reported EM-VEHs is in the range from 0.7 to 1450000 μW. However, the power production by the developed PE-VEHs ranges from 0.6 to 7700 μW. The overall size of most of the bridge VEHs is quite comparable and is in mesoscale. The resonant frequencies of EM-VEHs are on the lower side (0.13 to 27 Hz in comparison to PE-VEHs (1 to 120 Hz. The power densities reported for these bridge VEHs range from 0.01 to 9539.5 μW/cm3 and are quite enough to operate most of the commercial WASNs.