bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure‐stability correlations for imine formation in aqueous solution
Authors: Godoy‐Alcántar C. , Yatsimirsky Anatoly K. , Lehn J.‐M. 
Published: May 2005

AbstractImine formation between 25 aldehydes and 13 amines in aqueous solution in the pH range 7–11 was studied by 1H NMR spectroscopy. A three‐parameter linear equation correlating logarithms of imine formation constants with pKa and HOMO energies of amines and LUMO energies of aldehydes is proposed. In view of the widespread occurrence of imine‐forming processes in both chemistry and biology, the data presented are of significance for physical organic chemistry and of particular interest for dynamic combinatorial chemistry. Copyright © 2005 John Wiley & Sons, Ltd.
Greenish‐yellow‐, yellow‐, and orange‐light‐emitting iridium(III) polypyridyl complexes with poly(ε‐caprolactone)–bipyridine macroligands
Authors: Holder Elisabeth , Marin Veronica , Alexeev Alexander , Schubert Ulrich S. 
Published: May 2005

AbstractA set of novel greenish‐yellow‐, yellow‐, and orange‐light‐emitting polymeric iridium(III) complexes were synthesized with the bridge‐splitting method. The respective dimeric precursor complexes, [Ir(ppy)2‐μ‐Cl]2 (ppy = 2‐phenylpyridine) and [Ir(ppyCHO)2‐μ‐Cl]2 [ppyCHO = 4‐(2‐pyridyl)benzaldehyde], were coordinated to 2,2′‐bipyridine carrying poly(ε‐caprolactone) tails. The resulting emissive polymers were characterized with one‐dimensional (1H) and two‐dimensional (1H1H correlation spectroscopy) nuclear magnetic resonance and infrared spectroscopy, gel permeation chromatography, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, and the successful coordination of the iridium(III) centers to the 2,2′‐bipyridine macroligand was revealed. The thermal behavior was studied with differential scanning calorimetry and correlated with atomic force microscopy. Furthermore, the quantitative coordination was verified by both the photophysical and electrochemical properties of the mononuclear iridium(III) compounds. The photoluminescence spectra showed strong emissions at 535 and 570 nm. The color shifts depended on the substituents of the cyclometallating ligands. Cyclic voltammetry gave oxidation potentials of 1.23 V and 1.46 V. Upon the excitation of the films at 365 nm, yellow light was observed, and this could allow potential applications in light‐emitting devices. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2765–2776, 2005
Polymerization of (L,L)‐lactide and copolymerization with ϵ‐caprolactone initiated by dibutyltin dimethoxide in supercritical carbon dioxide
Authors: Stassin Fabrice , Jérôme Robert 
Published: May 2005

AbstractRing‐opening polymerization (ROP) of (L,L)‐lactide (LA) has been initiated by dibutyltin dimethoxide in supercritical carbon dioxide (sc CO2). Polymerization is controlled and proceeds at quasi the same rate as in toluene, which indicates that the reactivity of the propagating species is not impaired by parasitic carbonation reaction. Random copolymerization of LA with ϵ‐caprolactone (CL) has also been studied in sc CO2, and the reactivity ratios have been determined as 5.8 ± 0.5 for LA and 0.7 ± 0.25 for CL. These values have to be compared to 0.7 ± 0.25 for LA and 0.15 ± 0.05 for CL in toluene. Good control on ROP of CL and LA in sc CO2 has been confirmed by the successful synthesis of diblock copolymers by sequential polymerization of CL and LA. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2777‐2789, 2005
Effects of methylaluminoxane immobilization on silica on the performance of zirconocene catalysts in propylene polymerization
Authors: Smit Madri , Zheng Xuejing , Loos Joachim , Chadwick John C. , Koning Cor E. 
Published: May 2005

AbstractInvestigation of the characteristics and performance in propylene polymerization of silica‐immobilized methylaluminoxane (MAO), in combination with a moderately and a highly isospecific zirconocene catalyst, has revealed that a simple impregnation of silica with MAO at ambient temperature is insufficient to obtain uniform distribution of MAO throughout the support particle. Homogeneous Al distribution throughout the support, giving increased catalyst activity, was achieved by a more rigorous impregnation of silica with MAO at elevated temperatures. The highest catalyst activities were obtained by precontacting the MAO with the zirconocene to generate the activated species before immobilization on silica. Polymer particle morphology was strongly dependent on the characteristics of the silica used for catalyst immobilization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2734‐2748, 2005
Influence of organic solvents on cutinase stability and accessibility to polyamide fibers
Authors: Silva Carla , Matamá Teresa , Guebitz Georg M. , Cavaco‐Paulo Artur 
Published: May 2005

AbstractThe stability of cutinase was measured in the presence of dimethylacetamide (DMA) and benzyl alcohol (BA). These solvents are known swelling agents of polyamide fibers. We found that cutinase retains some stability (half‐life of 14 h), enough for an enzymatic treatment with a solvent composition of 1.5% DMA + 10% BA. Enzymatic treatment in the presence of these solvent compositions yields more soluble amino groups as well as more amino end groups at the fiber level. We have shown evidence that the presence of minor quantities of solvent can increase the accessibility of the enzyme towards the polyamide fiber. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2749‐2753, 2005
Quinone transfer radical polymerization (QTRP) of styrene: Catalysis by different metal complexes
Authors: Caille Jean‐Raphaël , Debuigne Antoine , Jérôme Robert 
Published: May 2005

AbstractStyrene has been polymerized by a Quinone Transfer Radical Polymerization (QTRP) based on the redox reaction of an ortho‐quinone and a metal catalyst. Several metal acetylacetonates have been tested in this work. The radical polymerization of styrene is largely controlled when phenanthrenequinone (PhQ) is used with catalytic amounts of Co(acac)2, Ni(acac)2, Mn(acac)2 or 3, and Al(acac)3. As a rule, in the presence of all these metallic complexes, the polystyrene molar mass increases with the monomer conversion, and polydispersity (Mw/Mn) is in the 1.3–1.6 range (at least until 40% monomer conversion). Styrene polymerization has also been resumed by polystyrene chains prepared by QTRP. In the specific case of manganese acetylacetonates, an amine or phosphine ligand has to be added for the control to be effective. Finally, two mechanistic hypotheses have been proposed, depending on whether the oxidation state of the metal can be easily changed or not. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2723‐2733, 2005
Preparation and characterization of biodegradable poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone) copolymers
Authors: Hong J.‐T. , Cho N.‐S. , Yoon H.‐S. , Kim T.‐H. , Lee D.‐H. , Kim W.‐G. 
Published: May 2005

AbstractA series of poly(trimethylenecarbonate‐ε‐caprolactone)‐block‐poly(p‐dioxanone) copolymers were prepared with varying feed rations by using two step polymerization reactions. Poly(trimethylenecarbonate)(ε‐caprolactone) random copolymer was synthesized with stannous‐2‐ethylhexanoate and followed by adding p‐dioxanone monomer as the other block. The ring opening polymerization was carried out at high temperature and long reaction time to get high molecular weight polymers. The monofilament fibers were obtained using conventional melting spun methods. The copolymers were identified by 1H and 13C NMR spectroscopy and gel permeation chromatography (GPC). The physicochemical properties, such as viscosity, molecular weight, melting point, glass transition temperature, and crystallinity, were studied. The hydrolytic degradation of copolymers was studied in a phosphate buffer solution, pH = 7.2, 37 °C, and a biological absorbable test was performed in rats. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2790–2799, 2005
Anionic polymerization of N,N‐dialkylacrylamides containing alkoxysilyl groups in the presence of Lewis acids
Authors: Kobayashi Motoyasu , Chiba Takashi , Tsuda Karin , Takeishi Makoto 
Published: May 2005

AbstractWith Ph2CHK as an initiator, the anionic polymerization of N‐propyl‐N‐(3‐triisopropoxysilylpropyl)acrylamide (4) and N‐propyl‐N‐(3‐triethoxysilylpropyl)acryl‐amide generated polymers with predicted molecular weights and narrow molecular weight distributions (MWDs) in the presence of Et2Zn or Et3B; however, the resulting polymers obtained in the absence of such Lewis acids had very broad MWDs. The results were ascribed to the coordination of the propagating anionic end to a relatively weak Lewis acid, in which the activity of the end anion was appropriately controlled for moderate polymerization without side reactions. A well‐defined diblock copolymer of 4 and N,N‐diethylacrylamide was also prepared with the binary initiating system of Ph2CHK and Et2Zn, whereas no such block copolymer was prepared by polymerization initiated with 1,1‐diphenyl‐3‐methylpentyllithium, as the propagating anion together with the lithium ion reacted with alkoxysilyl side groups on the poly(4) backbone to produce grafted polymers with high molecular weights. The hydrolysis of the alkoxysilyl side groups of poly(4) in acidic water yielded an insoluble gel. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2754‐2764, 2005
Thermal and X‐ray analysis of polymorphic crystals, melting, and crystalline transformation in poly(butylene adipate)
Authors: Woo E. M. , Wu Ming Chien 
Published: May 2005

AbstractPolymorphic crystals and complex multiple melting behavior in an aliphatic biodegradable polyester, poly(butylene adipate) (PBA), were thoroughly examined by wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). Further clarification on mechanisms of multiple melting peaks related to polymorphic crystal forms in PBA was attempted. More stable α‐form crystal is normally favored for crystallization from melt at higher temperatures (31–35 °C), or upon slow cooling from the melt; while the β‐form is the favored species for crystallization at low temperatures (25–28 °C). We further proved that PBA crystallization could also result in all α‐form even at low temperatures (25–28 °C) if it crystallized with the presence of prior α‐form nuclei. PBA packed with both crystal forms could display as many as four melting peaks (P1 ˜ P4, in ascending temperature order). However, PBA initially containing only the α‐crystal exhibited dual melting peaks of P1 and P3, which are attributed to dual lamellar distributions of the α‐crystal. By contrast, PBA initially containing only the β‐crystal could also exhibit dual melting peaks (P2 and P4) upon scanning. While P2 is clearly associated with melting of the initial β‐crystal, the fourth melting peak (P4), appearing rather broad, was determined to be associated with superimposed thermal events of crystal transformation from β‐ to α‐crystal and final re‐melting of the new re‐organized α‐crystal. Crystal transformation from one to the other or vice versa, lamellae thickening, annealing at molten state, and influence on crystal polymorphism in PBA were analyzed. Relationships and mechanisms of dual peaks for isolate α‐ or β‐crystals in PBA are discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1662–1672, 2005
Statistical analysis and prediction of protein–protein interfaces
Authors: Bordner Andrew J. , Abagyan Ruben 
Published: May 2005

AbstractPredicting protein–protein interfaces from a three‐dimensional structure is a key task of computational structural proteomics. In contrast to geometrically distinct small molecule binding sites, protein–protein interface are notoriously difficult to predict. We generated a large nonredundant data set of 1494 true protein–protein interfaces using biological symmetry annotation where necessary. The data set was carefully analyzed and a Support Vector Machine was trained on a combination of a new robust evolutionary conservation signal with the local surface properties to predict protein–protein interfaces. Fivefold cross validation verifies the high sensitivity and selectivity of the model. As much as 97% of the predicted patches had an overlap with the true interface patch while only 22% of the surface residues were included in an average predicted patch. The model allowed the identification of potential new interfaces and the correction of mislabeled oligomeric states. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Transport mechanism in mica and SiO2 dielectrics
Authors: Pipinys P. , Lapeika V. , Rimeika A. 
Published: May 2005

AbstractThe current–voltage (I–V) characteristics in mica have been measured at different temperatures. The I–V characteristics possessed a temperature dependence, which was more clearly evident at lower fields. A comparison of the experimental results with the Frenkel thermo‐emission theory and the theory of multiphonon‐assisted tunnelling of charge carriers from the impurity centers, has been performed. It is shown that the experimental data better agree with the phonon‐stimulated tunnelling theory than the Frenkel emission theory. Temperature‐dependent I–V characteristics of M–SiO2–Si structures measured by Waters and Van Zeghbroeck [Appl. Phys. Lett. 76(8), 1039 (2000)] are also reinterpreted in terms of the phonon‐assisted tunnelling processes. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Correlation between the metal–insulator transition and the electronic density of states near the Fermi level in oxygen‐deficient perovskite‐type NdBaCo2O5.5
Authors: Hidaka M. , Soejima M. , Soda M. , Sato M. , Choi Sun‐Hee , Sung Nark Eon , Kim Min Gyu , Lee Jay Min 
Published: May 2005

AbstractX‐ray absorption spectra near the absorption edges of Nd, Ba, and Co ions have been taken to study the metal–insulator (M–I) transition occurring at about 360 K (TMI) in NdBaCo2O5.5. In the metallic and insulating phases, the electronic density of states (DOS) just above the Fermi level (EF) consists of the high‐density unoccupied bands of Nd–5dσ and Ba–5dσ. The narrow charge‐transfer Co–3d7(eg)L band and the broad charge‐transfer Co–3d(t2g)nLm bands occupy positions just below and near EF, respectively, where L represent a hole in the O–2p valence band. The negative charge‐transfer Nd–4dnL′m and Ba–4dnL′m hybridized bands are also just below EF, where L′ represent a hole in the fully occupied 4d band of the Nd and Ba ions. It is suggested that the metallic conductivity above TMI arises from the itinerant (p–d) hybridized holes having an 3d(eg)‐symmetry in the top of the O–2p valence band. The structural deformation localized around the Ba ions but not the Nd and Co ions affects the crystal‐field splitting of the Co–3d orbitals in the CoO polyhedra and the hybridization between the outer orbitals of the cations (Nd, Ba, Co ions) and the O–2p orbitals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
ESR study of Sr‐doped LaCoO3 cobaltites
Authors: Phan T. L. , Bau L. V. , Khiem N. V. , Phuc N. X. , Yu S. C. 
Published: May 2005

AbstractThe electron spin resonance (ESR) method was used to investigate the internal spin dynamics of La1–xSrxCoO3 (x = 0.1, 0.2, 0.3) compounds in the temperature range 170 to ∼500 K. ESR spectra of the samples over the whole temperature range studied could be divided into three regions corresponding to different linewidths. This is due to the presence of an anisotropic field arising from ferromagnetic clusters. This is similar to manganite perovskites. The peak‐to‐peak ESR linewidth vs. temperature, ΔHpp(T), for the samples has a minimum value at a temperature Tmin (in this case Tmin ≈ 1.7TC, whereas Tmin ≈ 1.1TC for manganites). Asymmetric Lorentzian ESR spectra at temperatures T < Tmin become Gaussian at T > Tmin. ESR signals of La1–xSrxCoO3 cobaltites are thermally damped out at ∼460 K, this value being much lower than that for manganite compounds. The explanation of the experimental ΔHpp(T) data in the T > Tmin regime is based on the one‐phonon process and adiabatic hopping motion of small polarons. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Confined and interface polar optical phonon‐limited electron mobility in quantum wires
Authors: Vartanian Arshak L. 
Published: May 2005

AbstractThe electron mobility conditioned by confined and interface polar optical phonons for a quasi‐one‐dimensional cylindrical quantum wire embedded in a dielectric medium is investigated analytically. It is shown that the inclusion of the polar optical phonon confinement effects is crucial for accurate calculation of the low‐field electron mobility in the quantum wire. Taking into account the inelasticity of the electron–polar optical phonon interaction, the electron mobility is derived by a method that was successfully applied in three‐ and quasi‐two‐dimensional cases. The contribution of intersubband transitions to electron mobility for the GaAs quantum wire embedded in the AlxGa1–xAs medium is estimated. The extremums of the mobility dependences on wire radius and Al concentration are obtained. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Examining a square to triangular lattice interpolation: bound states in two dimensional t–J models
Authors: Basu Saurabh , Gooding R. J. 
Published: May 2005

AbstractFormation of bound pairs in two dimensional t–J models is investigated. Previous studies have examined the square and rectangular lattices, and here we extend such work to include the triangular lattice. In particular, we calculate the threshold exchange coupling needed for pairing, and the corresponding binding energy for an isotropic triangular lattice. Finally, to track how a frustrated environment affects pairing we have considered an anisotropic t–J model with two exchange couplings J1 and J2 which smoothly interpolates between the isotropic square to triangular lattices. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antiferro–ferromagnetic transformation in LaMnO3 under neutron irradiation
Authors: Chukalkin Yurii , Teplykh Alexander , Goshchitskii Boris 
Published: May 2005

AbstractUsing the methods of neutron and X‐ray diffraction analysis and magnetic measurements, polycrystalline samples of LaMnO3 were studied before and after irradiation with fast neutrons (En ≥ 1 MeV) at a fluence Φ = 5.5 × 1023 m–2. It was established that irradiation leads to the partial (∼5%) mutual disordering of the “lanthanum” and “manganese” sublattices. Ion displacements emerging at such radiation‐induced disordering lead to the destruction of the Jahn–Teller mode Q2 responsible for A‐type antiferromagnetism development in the initial sample. As a result, the antiferromagnet → canted ferromagnet magnetic transformation is observed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessment of various density functionals and basis sets for the calculation of molecular anharmonic force fields
Authors: Boese A. Daniel , Klopper Wim , Martin Jan M. L. 
Published: May 2005

AbstractIn a previous contribution, we established the suitability of density functional theory (DFT) for the calculation of molecular anharmonic force fields. In the present work, we have assessed a wide variety of basis sets and exchange‐correlation functionals for harmonic and fundamental frequencies, equilibrium, and ground‐state rotational constants, and thermodynamic functions beyond the rigid rotor‐harmonic oscillator (RRHO) approximation. The fairly good performance of double‐zeta plus polarization basis sets for frequencies results from an error compensation between basis set incompleteness and the intrinsic error of exchange‐correlation functionals. Triple‐zeta plus polarization basis sets are recommended, with an additional high‐exponent d function on second‐row atoms. All conventional hybrid generalized gradient approximation (GGA) functionals perform about equally well: high‐exchange hybrid GGA and meta‐GGA functionals designed for kinetics yield poor results, with the exception of of the very recently developed BMK functional, which takes a middle position along with the HCTH/407 (second‐generation GGA) and TPSS (meta‐GGA) functionals. Second‐order Møller–Plesset perturbation theory (MP2) performs similarly to these functionals but is inferior to hybrid GGAs such as B3LYP and B97‐1. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Relativistic LCGTO‐FF calculations of quantum‐size effects in plutonium films
Authors: Boettger Jonathan C. , Ray Asok K. 
Published: May 2005

AbstractLinear combinations of Gaussian‐type orbital–fitting function (LCGTO‐FF) calculations have been used to study quantum size effects in the work function and surface energy of unrelaxed ultra‐thin (001) films of fcc (δ) plutonium (Pu), up to five layers thick. Relativistic effects are included in the calculations using the second‐order Douglas–Kroll–Hess transformation, at the fully‐ and scalar relativistic levels of approximation, i.e., with and without spin‐orbit coupling terms included. In both approximations, the surface energy is found to be rapidly convergent, while the work function exhibits a significant quantum size effect up to the largest thickness considered. The (001) surface energies predicted are notably larger than the (111) surface energies found in similar calculations. The predicted work functions for the (001) and (111) surfaces agree to within the computational uncertainty due to the residual quantum size effect. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Simple Synthesis of Hierarchically Ordered Mesocellular Mesoporous Silica Materials Hosting Crosslinked Enzyme Aggregates
Authors: Lee Jinwoo , Kim Jungbae , Kim Jaeyun , Jia Hongfei , Kim Moon Il , Kwak Ja Hun , Jin Sunmi , Dohnalkova Alice , Park Hyun Gyu , Chang Ho Nam , Wang Ping , Grate Jay W. , Hyeon Taeghwan 
Published: May 2005

AbstractHierarchically ordered mesocellular mesoporous silica materials (HMMS) were synthesized using a single structure‐directing agent. The mesocellular pores are synthesized without adding any pore expander; the pore walls are composed of SBA‐15 type mesopores. Small‐angle X‐ray scattering revealed the presence of uniform pore structures with two different sizes. Using HMMS as a nanoscopic template, hierarchically ordered mesocellular mesoporous carbon (HMMC) and polymer (HMMP) materials were synthesized. HMMS was used as a host for enzyme immobilization. To improve the retention of enzymes in HMMS, we adsorbed enzymes, and then employed crosslinking using glutaraldehyde (GA). The resulting crosslinked enzyme aggregates (CLEAs) show an impressive stability with extremely high enzyme loadings. For example, 0.5 g α‐chymotrypsin (CT) could be loaded in 1 g of silica with no activity decrease observed with rigorous shaking over one month. In contrast, adsorbed CT without GA treatment resulted in a lower loading, which further decreased due to continuous leaching of adsorbed CT under shaking. The activity of crosslinked CT aggregates in HMMS was ≈10 times higher than that of the adsorbed CT, which represents a 74‐fold increase in activity per unit weight of HMMS due to higher CT loading.
The European Convention Method in Hindsight
Authors: Sap John W. 
Published: May 2005

PETER NORMAN, The Accidental Constitution, the story of the European Convention. Brussels: EuroComment, 2003, 406 p. ISBN 9077110054KLEMENS H. FISCHER, Konvent zur Zukunft Europas. Texte und Kommentar. Baden-Baden: Nomos Verlagsgesellschaft, 2003, 542 p. ISBN 383290171XETIENNE DE PONCINS, Vers une Constitution européenne. Texte commenté du projet de traité constitutionnel établi par la Convention européenne. Paris: Editions 10/18, 2003, 528 p. ISBN 2264038179VALÉRY GISCARD D'ESTAING, La Constitution pour l'Europe. Paris: Editions Albin Michel, 2003, 396 p. ISBN 2226142010JEAN-LUC DEHAENE, De Europese uitdaging. Van uitbreiding tot integratie. Leuven: Van Halewyck, 2004, 237 p. ISBN 9056175645