bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxygen‐carrying plasma hemoprotein “albumin‐heme”: nitric oxide binding and physiological responses after administration in vivo
Authors: Tsuchida Eishun , Komatsu Teruyuki 
Published: December 2003

AbstractRecombinant human serum albumin complexed with tetraphenylporphinatoiron(II) derivative, “albumin‐heme (rHSA‐FeP)”, is a synthetic oxygen (O2)‐carrying plasma hemoprotein, which becomes a new class of red blood cell substitute. The UV‐vis. absorption and ESR spectroscopy revealed that rHSA‐FeP formed six‐coordinate nitrosyl complex after exposure of nitric oxide (NO) gas. Although the NO‐binding affinity of rHSA‐FeP (P1/2NO: 1.7 × 10−6 Torr, pH 7.3, 25°C) is 9‐fold higher compared to that of hemoglobin (Hb), the administration of this artificial hemoprotein solution into anesthetized rat does not induce an acute increase in blood pressure (hypertension), which is often observed in Hb‐based O2‐carriers due to the depletion of NO (endothelial derived relaxing factor).
Molecularly controlled blending of metals and organic metals with polyolefins for the preparation of materials with modulated optical properties
Authors: Pucci Andrea , Elvati Paolo , Ruggeri Giacomo , Liuzzo Vincenzo , Tirelli Nicola , Isola Mauro , Ciardelli Francesco 
Published: December 2003

AbstractIn this paper, after revisiting previous data on terthiophene molecules, several attempts are described to use metal containing species such as nanoclusters and molecular complexes as dispersed chromophores in the same ethylene polymer matrix in order to extend an approach to new classes of molecules and improve some specific optical responses including fluorescence dichroism and behaviour as linear optical polarizers is evaluated. Comparison with typical linear polarizers from the same polymer and terthiophenes of innovative gold clusters is discussed as well as transition metal complexes.
Proton‐conducting polymer membranes for direct methanol fuel cells
Authors: Won Jongok , Kang Yong Soo 
Published: December 2003

AbstractThree methods to block the methanol transport through proton‐conducting polymer membranes while maintaining the proton conductivity unchanged have been conducted; 1) selective layer formation on the surface of the membrane, 2) prearation of nanoclay composite membrane providing tortuous pathway of methanol, 3) control and fixation of the proton transport channels. The methanol permeability through the membranes decreased significantly at the expense of the small decrease in the proton conductivity. It is thus concluded that both the structure and the fixation of the proton transport channels are crucial in optimizinging proton conducting membranes for direct methanol fuel cells.
Synthesis of azo‐conjugated catecholate complexes and their photo‐ and proton‐responses
Authors: Nagashima Sayoko , Nihei Masayuki , Yamada Teppei , Murata Masaki , Kurihara Masato , Nishihara Hiroshi 
Published: December 2003

AbstractA new azo‐conjugated catecholate ligand, azocat, and its nickel complexes were synthesized, and their physical and chemical properties were investigated. The complex with one azocat shows no obvious photo‐response, whereas the compound with two azocat's causes a little photoisomerization. Both of these novel azo‐conjugated catecholate complexes show remarkable proton responses.
Effect of supercritical CO2 on bulk hydrogenation of nitrile butadiene rubber catalyzed by RhCl(PPh3)3
Authors: Li Guanghui , Pan Qinmin , Rempel Garry L. , Ng Flora T.T. 
Published: December 2003

AbstractThe effect of supercritical (SC) CO2 on the bulk hydrogenation of NBR entrapped with the catalyst (RhCl(PPh3)3) was investigated under various reaction times, reaction temperatures, hydrogen pressures and loadings of the catalyst and the thicknesses of the polymer films. CO2 helps in improving the transport behaviour of catalyst in polymer matrices, as well as helping to move catalyst into or out of the polymer. A method for the measurement of the dissolution extent or the apparent solubility of the Rh based catalyst in SC‐CO2 was developed. It is found that high temperatures and high SC‐CO2 densities would enhance the apparent solubility. Cosolvents, such as acetone, are also found to increase the apparent solubility. Details on the hydrogenation process are also presented.
Electrochemical reduction of carbon dioxide catalyzed by cofacial dinuclear metalloporphyrin
Authors: Enoki Osamu , Imaoka Takane , Yamamoto Kimihisa 
Published: December 2003

AbstractCofacial dinuclear metalloporphyrins exhibited a catalytic activity for the electrochemical reduction of carbon dioxide. The cofacial dinuclear porphyrin was automatically generated by mixing a cationic cobalt porphyrin (CoTMPyP) and an anionic metalloporphyrin (MTPPS) in solution. The redox system of this complex was examined by electrochemical methods. According to the cyclic voltammogram, the catalytic active species was generated at −1.8V vs. Ag/Ag+, which was considered to be a monovalent cobalt porphyrin, Co(I)TMPyP. The catalytic activity of the dinuclear complex was two times greater than that of the mononuclear one because the anionic porphyrin acted as an electron mediator.
Supramolecular catalytic systems based on calixarenes and cyclodextrins
Authors: Karakhanov Edward E. , Maksimov Anton L. , Runova Elena A. , Kardasheva Yulia S. , Terenina Maria F. , Buchneva Tatyana S. , Guchkova Anna Ya. 
Published: December 2003

AbstractA number of supramolecular metal complex catalitic system based on cyclodextrins and calixarenes have been developed. Particular attention has been given to design of new metal complexes with molecular recognition abilities. Data on application catalytic systems based on receptor molecules capable to formation of inclusion “host‐guest” complexes in hydroformylation and Wacker‐oxidation are given. Influence of different factors on activity, stability, selectivity of metal complex supramolecular catalytic systems is discussed.
Polyfunctional activity of metal complexes containing 2,6‐Di‐tert‐butylphenol in catalytic oxidation
Authors: Milaeva Elena R. , Shpakovsky Dmitry B. , Petrosyan Valery S. 
Published: December 2003

AbstractThe results of the investigations of metal complexes containing 2,6‐di‐tert‐butilphenol in the ligand environment in catalytic homogeneous oxidation of organic compounds are reviewed. The liquid‐phase oxidation of hydrocarbons, olefins, aminophenol and unsaturated fatty acids by molecular oxygen in the presence of phthalocyanines, porphyrins, σ‐aryl and π‐allyl transition metal complexes is described. The change of the reactivity of organometallic and coordination compounds by oxidation of the redox active phenolic group opens up the possibility to use them as polyfunctional catalytic systems showing positive and/or negative catalytic effects.
Oxidation of catecholamines on chitosan‐immobilized Co(II) salen complexes
Authors: Finashina E.D. , Kramareva N.V. , Kustov L.M. 
Published: December 2003

AbstractL‐Adrenaline and 3,4‐dihydroxyphenylalanine (dopa) oxidation by molecular oxygen in the presence of the Co(II) complex of bis(salicylideneethylene diamine) (CoSalen) immobilized on unmodified chitosan and chitosan modified by 4‐pyridinecarboxaldehyde is studied in aqueous solutions under mild conditions. The catalysts prepared are selective with respect to oxidation of the chosen substrates. Preparation of binary composite egg‐shell systems, with a thin film of low‐loaded CoSalen‐chitosan supported on macroporous SiO2 makes it possible to increase sufficiently the specific surface area and the efficiency of the catalyst.
Recent progress in applications of ligand‐stabilized metal nanoclusters
Authors: Toshima Naoki 
Published: December 2003

AbstractDue to a nanotechnology boom in science and technology, the metal nanoclusters or nanoparticles stabilized by polymers and organic ligands have achieved much attention recently all over the world. We have studied on the preparation of polymer‐stabilized metal nanoclusters by chemical methods, and applied them mainly to catalyses. Here the recent progresses in our group are presented in the structure control of bimetallic and trimetallic nanoclusters and in the applications of metal nanoclusters not only to the catalyses but also to the sensing responsive to pH and molecular recognition, and to the electro‐optic properties of liquid‐crystalline display rapidly responsive to frequency modulation. Preparation of trimetallic nanoclusters with a triple core/shell structure is especially emphasized to serve as a very active catalyst at a special atomic ratio of three elements.
Metal catalysis to improve compatibility at PO/PET blends interfaces
Authors: Coltelli Maria‐Beatrice , Bianchi Sabrina , Savi Stefania , Liuzzo Vincenzo , Aglietto Mauro 
Published: December 2003

AbstractReactive blending of 70/30 by weight PET/polyolefin (PO) mixtures was carried out in a discontinuous mixer using a polyolefin functionalized with dialkyl maleates and potential transesterification catalysts to improve the formation of graft PO‐PET copolymers. The yield of this reaction was evaluated by the analysis of FT‐IR spectra of blends residual fraction after selective extractions of unreacted polyester. The building of a calibration curve and the analysis of the spectra by deconvolution was performed to evaluate the percentage of grafted PET. The results are discussed in terms of influence of the different catalysts and of polyolefin structure on the blends morphology.
The complexes of macromolecules and metal nanoparticles: pseudo‐template synthesis and behavior
Authors: Papisov I.M. 
Published: December 2003

AbstractMetal sols composed of metal nanoparticles (1 ‐ 10 nm in diameter) protected with polymer molecules may be regarded as dispersions of polymer‐metal complexes formed due to cooperative non‐covalent (e.g., hydrophobic, coulombic) interaction of polymer chains with the surface of metal nanoparticles. The sols are commonly prepared by reducing of metal ions in solutions of appropriate polymers.The interactions between macromolecules and nanoparticles are reversible. In the case of long polymer chains and minute particles, the equilibrium constant of the reaction exponentially depends on the surface area of the particle. The probability of mutual “recognition” (complex formation) of growing particle and a macromolecule rapidly increases from practically zero to practically unity in narrow interval of the particle's diameters. The recognition is followed with the shadowing of the particles and the stop of their growths. Such kind of processes was termed “pseudo‐template”. In frame of the concept of pseudo‐template processes can be estimated: (1) the conditions at which sol particles of desirable size can be prepared, (2) the influence of temperature, polymer concentration, nanoparticles size, and other conditions on the stability of polymer ‐ particle complex having been prepared, and (3) the conditions at which stable sol does not exist and can not be prepared at all.The interactions between metal nanoparticles and macromolecules are highly selective regard to the structure of polymer chains. The property can be effectively used for the control the size characteristics of metal nanoparticles (in course of their formation) and the stability of metal sols.The selectivity provides high conversions in catalytic chemical modification reactions in which a macromolecule is the substrate and a component of the catalyst in the same time. As an example, the hydrolysis of lactame groups in monomer unites of poly(N‐vinyl pyrrolidone) catalyzed with copper sols is discussed.
Combined XPS and AFM study of cluster‐containing polymers based on Rh
Authors: Lyakhovich Alevtina M. , Mikhailova Sophia S. , Pomogailo Svetlana I. , Dzhardimalieva Gulzhian I. , Pomogailo Anatolii D. 
Published: December 2003

AbstractRh6‐ monomer and polymer‐immobilized complexes have been characterized using XPS and AFM. Polymer‐immobilized clusters were obtained by the reaction of Rh6(CO)15CH3CN with copolymer of allyldiphenylphosphine and styrene. AFM study shows the change of surface morphology of the above copolymers. XPS data demonstrated the change of charge state of Rh atoms under monosubstitution of the CO‐group for Rh6‐ monomer complexes as well as in copolymer cluster complexe after the catalysis process of hydrogenation.
Magnetic properties of polymer matrix nanocomposites on a basis of metal carboxylates
Authors: Leonowicz Martin K. , Lawecka Marta , Ślawska‐Waniewska A. , Dzhardimalieva Gulzhian I. , Rozenberg Aleksander S. , Pomogailo Anatolii D. 
Published: December 2003

AbstractMetallopolymer nanocomposites on the bases of cobalt and iron acrylates as well as their cocrystallites have been obtained and characterized. Microstructure of the materials consists of both agglomerated and individual nanocrystallites which are homogeneously distributed in the polymer matrix. Mean crystallite size is 7‐14 nm. All the composite materials exhibit soft magnetic properties at room temperature. The magnetic parameters are controlled by the intrinsic magnetic properties of the constituents and agglomeration of the particles.
Conformational switching between carboxylic acid and carboxylate anion states by NH‐O hydrogen bonding
Authors: Ueyama Norikazu , Takahashi Kazuyuki , Onoda Akira , Okamura Takaaki , Yamamoto Hitoshi 
Published: December 2003

AbstractBiologically important Ca‐proteins and Ca‐biominerals as metal‐polymer complexes are often regulated by the complexation and demetalation with the biopolymers. Metal‐oxygen bond is supported by NH···O hydrogen bonds between coordinating oxyanion and neighboring amide NH and by the successive hydrogen bonding networks. Carboxylate anion under hydrophobic conditions has a high basicity that leads to a covalent Ca‐O bond character that is significantly affected by the NH···O hydrogen bond. The hydrogen bonds in Asp‐containing tripeptide fragments in Ca‐proteins presumably control coordination/dissociation of metal‐oxygen bonds. Our systematic studies of carboxylate, sulfonate and phosphate Ca(II) complexes demonstrate a relationship between the basicity of oxyanion in carboxylate and hydrogen bonds as cooperating with the oligopeptide conformation in Asp‐containing Ca(II) complexes. Hydrogen bonds between carboxylate oxyanion and amide NH, controlled by a conformational switching of oligopeptide fragments, seem to be one of essential factors for the regulatory formation of Ca‐proteins and nano‐architectures in connection with the interface structure of inorganic and organic phases in biominerals.
Transverse Stark effect of electrons in a semiconducting quantum wire
Authors: Vázquez G. J. , del Castillo‐Mussot M. , Spector Harold N. 
Published: December 2003

AbstractWe investigate the effect of an electric field applied tranversely to the axis of cylindrical symmetry of a cylindrical quantum wire on the ground‐state energy of the electrons in the wire using an infinite confining potential well model. For low electric fields, we find a quadratic shift of the energy levels with the electric field; while for strong fields, the Stark shift of the ground‐state energy increases almost linearly with the electric field. This increase is greater for wide wires, but for narrow wires, the Stark shift of the ground‐state energy does not change much with the electric field. Also, at higher electric fields, the Stark shift of the ground‐state energy increases with increasing wire radius. This will lead to the decrease of the effective bandgap of a semiconducting quantum wire with electric field. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impurity breakdown under transverse runaway of hot electrons
Authors: Metreveli N. K. , Kachlishvili Z. S. , Chumburidze F. G. , Tskipuri L. T. 
Published: December 2003

AbstractIn the transverse electric and magnetic field, in Hall regime the low‐temperature impurity breakdown (IB) under transverse runway (TR) conditions is considered. The effect of the increase in the compensation degree on the IB and TR applied electric field ratio is studied at different values of the magnetic field. It is shown, that with the increase in the magnetic field critical electric fields relevant to IB and TR must tend to each other, while at the fixed magnetic field the IB critical field approaches the TR threshold field with the increase in the compensation degree. The obtained results are at variance with the well‐known fact that the applied breakdown field tends to infinity at C0 → 1, that is to say when the concentration of free charge cariers tends to zero; in asymptotics the applied breakdown and threshold fields merge. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of in‐plane anisotropy on specific heat jump of MgB2
Authors: Udomsamuthirun P. , Rakpanich S. , Yoksan S. 
Published: December 2003

AbstractAn analytical result for the normalized jump of the heat capacity ΔC/CN is derived for in‐plane anisotropic s‐wave superconductors within the framework of the weak‐coupling BCS approach. Our results show that within the anisotropy gap model the value of ΔC/CN must be less than the BCS value and the effect of in‐plane asymmetry will reduce or increase the value of ΔC/CN of in‐plane symmetry depending on its parameters. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Out‐of‐plane transport in Bi2−xPbxSr2Co2Oy single crystals
Authors: Li H. L. , Ruan K. Q. , Wang Q. , Chen Y. , Qian S. , Yu Y. , Huang S. L. , Zheng Z. , Wang C. Y. , Cao L. Z. 
Published: December 2003

AbstractThe transport properties of Bi2−xPbxSr2Co2Oy single crystals with various Pb contents are studied. The in‐plane resistivity ρab always shows metallic behavior from room temperature (290 K) to 80 K with various Pb contents, while the out‐of‐plane resistivity ρc shows rather complex behavior. For Pb‐free samples, ρc shows semiconductive behavior in the measured temperature range. With increasing Pb content, the temperature dependence of ρc shows an evolution from semiconductive through crossover to metallic behavior. According to the formula for ρc proposed previously, the evolution of ρc behavior is fitted well. Using the small polaron theory, the complex behavior of ρc is interpreted. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure calculationsof magnesium chalcogenides MgS and MgSe
Authors: Rached D. , Benkhettou N. , Soudini B. , Abbar B. , Sekkal N. , Driz M. 
Published: December 2003

AbstractTheoretical results on the structural and the electronic properties of MgS and MgSe are presented. The calculations were made using the full‐potential linear muffin‐tin orbitals (FP‐LMTO) method augmented by a plane wave (PLW) basis. It was found that the electronic properties in the B1, B3 and B4 structures of these magnesium chalcogenides show good agreement compared to other works. Through these results the power of these calculation methods applied to the magnesium chalcogenides was confirmed. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐temperature properties of a mixed spin Heisenberg ferrimagnetic system on a honeycomb lattice
Authors: Li Jun , Du An , Wei Guozhu 
Published: December 2003

AbstractThe low‐temperature properties of a mixed spin‐2 and spin‐5/2 Heisenberg ferrimagnetic system on a honeycomb lattice are studied using a linear spin‐wave theory. The magnetizations and the internal energy at zero and low temperature, the spin‐wave spectrum, and the specific heat are calculated. The effects of the interlayer interaction and the anisotropy are discussed. It is found that the spin‐wave spectrum breaks into two optical branches from the effects of the anisotropy and there is no expected acoustical branch when there is single‐ion anisotropy. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermodynamic properties of a spin‐1 antiferromagnetic chain with an anisotropy at a finite temperature
Authors: Li Jia‐Liang , Zhu Su‐Hua 
Published: December 2003

AbstractIn this paper a self‐consistent mean‐field approximation is used to study the thermodynamic properties of a spin‐1 antiferromagnetic Heisenberg chain with an anisotropy in the presence of an external magnetic field at a finite temperature. The temperature dependences of the internal energy, Haldane gap, and correlation length are presented. It is found that the internal energy and Haldane gap increase with increasing temperature, while the correlation length decreases for a fixed magnetic field and single‐ion anisotropy. The magnetic field splits the Haldane gap into two branches: the upper branch increases with increasing magnetic field while the other branch decreases. The numerical results are consistent with those of other theoretical methods. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure of magnesium diboride and related compounds
Authors: Paduani C. 
Published: December 2003

AbstractThe electronic structure of AlB2‐type diborides and related compounds has been investigated in first‐principles calculations with the molecular cluster discrete variational method. For MgB2 was studied the effect of the lattice relaxation on the total density of states at the Fermi energy (N(ϵF)). The results indicated that a contraction of about 2% in the lattice spacings a and c can lead to a slight increase of N(ϵF) for boron. In the MB2 diborides, M = Al, Ti, V, Cr, Zr, Nb, Mo and Ta, the largest contributions to N(ϵF) is observed for Cr, Mo and Nb. TiB2 possess the highest chemical stability in the series. The electronic specific heat coefficient γ also is calculated for the diborides. The method is employed to obtain the partial B2p contribution to the total DOS at the Fermi level with the introduction of a monolayer of solute atoms as a substitution for Mg atoms of Na, Al, Ca, Ti, V, Cr, Zr, Nb, Mo and Ta in layered superstructures … /M/B2/Mg/B2/ … . A stronger covalent bonding between boron atoms is identified in these cases. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental and analytical study of defect structures in nonstoichiometric lithium tantalate and lithium niobate
Authors: Masaif N. , Jebbari S. , Bennani F. , Hafid M. , Jennane A. 
Published: December 2003

AbstractFrom the experimental measurements of Curie temperature using a theory of ferroelectric transition, LiTaO3 and LiNbO3 solid solutions have been investigated. A comparison between the lithium tantalate and lithium niobate is given. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure and magnetic properties of bcc Fe–Ni alloys
Authors: Paduani C. 
Published: December 2003

AbstractIn this work we present first‐principles electronic structure calculations with the molecular cluster discrete variational method to study Fe–Ni alloys in the bcc phase. The spin‐polarized calculations are based on a local‐density approximation of the density‐functional theory. The local moments are obtained for several configurations in 51‐atoms clusters, which include four shells of neighbors to study the behavior of the magnetic moments upon alloying iron–nickel. The calculations indicate that the local Fe moment increases slightly at lower concentrations, but decreases at higher Ni contents, whereas the Ni moment is practically constant. The calculated hyperfine field (Fermi contact term) decreases by increasing the nickel concentration in the alloys. In layered systems a first investigation indicates that the Ni atoms at the inner layers show an enhanced moment relative to surface layers, as verified by experiment. In the source is a populational effect, which arises from a depleted occupation in the minority spin channel. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resonant tunnelling in the presence of intense laser fields
Authors: Saczuk E. , Kamiński J. Z. 
Published: December 2003

AbstractIt is shown, by solving numerically the time‐dependent Schrödinger equation, that the resonant transmission of electrons through double barrier structures can significantly be modified and controlled by intense laser fields. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)