bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and Characterization of a Cyclic Compound Consisting of Bis(diphenylphosphino)acetylene Joined Alkyne-Bridged Dicobalt Fragments
Authors: Hong Fung-E , Chang Hao , Chang Yu-Chang , Ko Bao-Tsan 
Published: April 2003

Abstract
A cyclic compound, [Co2(CO)4(µ2-HC≡CSiMe3)(PPh2C≡CPPh2)]2 2, was identified from the reaction of bis(diphenylphosphino)acetylene with an alkyne-bridged dicobalt complex, (µ2-HC≡CSiMe3)Co2(CO)6 1. Crystal structure of 2 shows that it is a twelve-membered ring complex comprised of two DPPA coordinated pseudo-tetrahedral Co2C2 units. Further reaction of 2 with two equivalents of Co2(CO)8 resulted in the conversion of 2 into [Co2(CO)6{µ-P, P-(µ-PPh2C≡CPPh2)}] [Co2(CO)4(µ-HC≡CSiMe3)] 3.
Cyclic Voltammetric Responses in Hybrid Formation of 2′-Anthraquinone-Modified Oligonucleotide with DNA
Authors: Yamana Kazushige , Kumamoto Satoshi , Nakano Hidehiko , Matsuo Yoshiaki , Sugie Yosohiro 
Published: April 2003

Abstract
Electrochemical properties of oligonucleotides possessing an anthraquinonylmethyl group at 2′-sugar residue have been investigated. The anthraquinone oligomers exhibited measurable changes in cyclic voltammeric responses upon hybridization with DNA.
Hydrolytic Activity of ZnIIZnII and ZnIIBaII Complexes toward Tri(p-nitrophenyl) Phosphate and Di(p-nitrophenyl) Phosphate: A Functional Model of Heterobimetallic Phosphodiesterase
Authors: Arimura Keisuke , Ohba Masaaki , Yokoyama Takushi , Okawa Hisashi 
Published: April 2003

Abstract
Dinuclear hydroxo ZnIIZnII and ZnIIBaII core complexes, derived from a macrocyclic compartmental ligand, are examined in their hydrolytic activity toward tri(p-nitrophenyl) phosphate (TNP) and sodium di(p-nitrophenyl) phosphate (NaDNP) in aqueous DMSO. TNP is hydrolyzed by both complexes. On the other hand, DNP− is hydrolyzed by the ZnBa complex but not by the ZnZn complex.
Effects of Molecular Association in the Radical-Cations of 1,8-Bis(ethylenedithiotetrathiafulvalenyl)naphthalene
Authors: Iyoda Masahiko , Hasegawa Masashi , Kuwatani Yoshiyuki , Nishikawa Hiroyuki , Fukami Kentaro , Nagase Shigeru , Yamamoto Gaku 
Published: April 2003

Abstract
The π–π interaction of the tetrathiafulvalenyl groups in 1,8-bis(ethylenedithiotetrathiafulvalenyl)naphthalene was investigated. The novel electronic properties of neutral and cationic tetrathiafulvalenes have been revealed on the basis of the X-ray analysis, spectral analyses, and DFT calculations.
Superoxide Anion Generation via Electron-Transfer Oxidation of Catechin Dianion by Molecular Oxygen in an Aprotic Medium
Authors: Nakanishi Ikuo , Fukuhara Kiyoshi , Ohkubo Kei , Shimada Tomokazu , Kansui Hisao , Kurihara Masaaki , Urano Shiro , Fukuzumi Shunichi , Miyata Naoki 
Published: April 2003

Abstract
Superoxide anion (O2•−) was generated via an electron-transfer oxidation of catechin dianion, which was produced in the reaction of catechin with two equivalents of methoxide anion, by molecular oxygen in acetonitrile. From the detailed spectroscopic and kinetic analyses was determined the rate constant for the formation of O2•− to be 5.8 × 10−2 mol−1 dm3 s−1.
Convenient Synthesis of (3S,5S)-5-Hydroxy- and (3R,5S)-5-Chloropiperazic Acids of a Peptide Antibiotic, Monamycin G3
Authors: Ushiyama Reiko , Yonezawa Yasuchika , Shin Chung-gi 
Published: April 2003

Abstract
Convenient synthesis of (3S,5S)-5-hydroxy- and (3R,5S)-5-chloropiperazic acids, which are the important constituting moieties of an antibiotic monamycin G3, and their possible stereoisomers constructing of similar antibiotics was achieved from d- and l-glutamic acids in short steps.
Fluorescence Responses on Ion Recognition with 2-(4-Dialkylaminophenyl)ethoxyantimony(V) Tetraphenylporphyrin
Authors: Andou Yoshito , Shima Kensuke , Shiragami Tsutomu , Yasuda Masahide 
Published: April 2003

Abstract
The effects of metal ions on the fluorescence spectra of 2-phenylethoxyhydroxyantimony(V) tetraphenylporphyrin hexa-fluorophosphate (1a–c) involving azacrown ether on axial ligands were investigated. Trivalent metal ions such as Al3+, In3+, Ga3+, and Lu3+ which undergo the complexation with the azacrown ether remarkably enhanced the fluorescence quantum yields.
Dynamics of Silylenes in Polysilylenes with Structural Defects by Excimer Laser Flash Photolysis
Authors: Seki Shu , Tsuji Shou , Matsui Yoshinori , Tagawa Seiichi 
Published: April 2003

Abstract
The dynamics of silylene extrusion reaction was observed in polysilylene with Si branchings by using KrF excimer laser flash photolysis technique. The initial yield of silyl radicals was seen to be dependent on the backbone structure of polysilylenes, whereas the yield of silylenes was almost proportional to the number of the linear Si units in their backbones.
UV Absorption and Fluorescence Properties of Pyrene Derivatives Having Trimethylsilyl, Trimethylgermyl, and Trimethylstannyl Groups
Authors: Maeda Hajime , Inoue Yohtaro , Ishida Hideki , Mizuno Kazuhiko 
Published: April 2003

Abstract
UV absorption maxima of trimethylsilyl-, trimethylgermyl-, and trimethylstannyl-substituted pyrenes shifted to longer wavelength than that of unsubstituted pyrene. Absorption maxima of mono-, bis-, tris-, and tetrakis(trimethylsilyl)pyrenes shifted to longer wavelength consecutively at intervals of 10 nm. Fluorescence intensities and lifetimes decreased in the order of Me3SiAr &gt; Me3GeAr &gt; Me3SnAr. Fluorescence intensity of 1,3,6,8-tetrakis(trimethylsilyl)pyrene was the largest among those of a series of pyrenes.
Dynamics of Water Molecules in Micropores of AlPO4-5 and SAPO-5 Studied by 1H NMR
Authors: Gotoh Kazuma , Ishimaru Shin’ichi , Ikeda Ryuichi 
Published: April 2003

Abstract
Dynamics of water molecules in one-dimensional micropores AlPO4-5 and SAPO-5 frameworks was studied by measuring 1H NMR spectra, second moment M2 of line-width and spin-lattice relaxation time T1. Although the presence of two kinds of water molecules free and bound on the capillary wall were reported in AlPO4-5, our NMR T1 results imply the absence of two kinds of H2O motions, but the motional rate distributes from slow to fast jumps in both AlPO4-5 and SAPO-5.
Synthesis, Structure, and Reactions of a Novel Triarylsilanol with a Bowl-Type Framework: A Silanol Extremely Resistant to Self-Condensation
Authors: Goto Kei , Okumura Tomoko , Kawashima Takayuki 
Published: April 2003

Abstract
A novel nano-scale triarylsilanol bearing a bowl-shaped framework was synthesized, the structure of which was established by X-ray crystallographic analysis. The silanol was found to be extremely resistant to self-condensation whereas it reacted easily with appropriate molecules to give the corresponding derivatives.
The First [5]Supercyclodextrin Whose Cyclopentameric Array Is Held Only by a Mechanical Bond
Authors: Kaneda Takahiro , Yamada Takashi , Fujimoto Tatsuhiko , Sakata Yoshiteru 
Published: April 2003

Abstract
The first [5]supercyclodextrin 1s whose nano-sized cyclopentameric array is held only by a mechanical bond was synthesized by the pentakis-azo coupling of a new hermaphrodite monomer 2 with 2-naphthol as a stopper, isolated by chromatography, and characterized by MS, 2D NMR, and vis spectral methods with the help of computer simulation.
Hydrothermal Synthesis and Characterization of SnS2 Nanocrystals
Authors: Wang Chunrui , Tang Kaibin , Yang Qing , Qian Yitai , Xu Cunyi 
Published: April 2003

Abstract
Nanocrystalline SnS2 was synthesized by a hydrothermal reaction between SnCl4·5H2O and thiourea (NH2CSNH2) at 140–200 °C. XRD pattern indicated that the as-prepared sample was β-phase SnS2. The as-prepared SnS2 mainly consisted of hexagon slices with average diameter of 30–200 nm. A Raman spectrum of the as-synthesized β-SnS2 was presented.
Synthesis and Properties of Tetrathiafulvalene-Substituted Ferrocenes
Authors: Iyoda Masahiko , Takano Takahiro , Otani Naoki , Ugawa Kohei , Yoshida Masato , Matsuyama Haruo , Kuwatani Yoshiyuki 
Published: April 2003

Abstract
1-Tetrathiafulvalenylferrocene and its derivatives have been synthesized in moderate to good yields employing palladium-catalyzed cross-coupling. The oxidation potentials of the title compounds revealed enhanced donor ability of the TTF unit, whereas the donor ability of the ferrocene moiety decreased markedly. The radical-cation salts derived from 1-tetrathiafulvalenylferrocenes are semiconductors.
Dehydrogenative Coupling of Monohydrosilanes Mediated by (2-Phosphinoethyl)silylrhodium(I) Complex
Authors: Okazaki Masaaki , Ohshitanai Shin , Tobita Hiromi , Ogino Hiroshi 
Published: April 2003

Abstract
Treatment of HSiMe2Ph with a square-planar rhodium(I) complex Rh[(κ2-Si,P)-Me2SiCH2CH2PPh2](Pme3)2 gave rise to selective dehydrogenative coupling of hydrosilanes to afford (SiMe2Ph)2 and RhH2[(κ2-Si,P)-Me2SiCH2CH2PPh2](Pme3)2.
Rh–Pt Heterobimetallic Complexes with Unsymmetrically Bridging Organosilyl Ligands: Crystal Structure and Dynamic Behavior in Solution
Authors: Tanabe Makoto , Osakada Kohtaro 
Published: April 2003

Abstract
Pt{SiH(C6H4F-4)2}2(Pme3)2 reacts with Rh (I) complexes to afford new Rh–Pt heterobimetallic complexes with bridging hydrido and diarylsilyl ligands. These complexes were characterized by X-ray crystallography. The NMR spectra exhibit dynamic behavior of hydrogen atoms and three Pme3 ligands bonded to Rh center in solution.
Dehydrogenative Silylation of Ketones Catalyzed by Diphosphinidenecyclobutene-Coordinated Platinum(II) Complexes
Authors: Ozawa Fumiyuki , Yamamoto Shogo , Kawagishi Seiji , Hiraoka Masatomi , Ikeda Shintaro , Minami Tatsuya , Ito Shigekazu , Yoshifuji Masaaki 
Published: April 2003

Abstract
Methylplatinum triflate coordinated with 1,2-diphenyl-3,4-bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobutene serves as a highly selective catalyst for dehydrogenative silylation of ketones with HSiMe2Ph in the presence of pyridine as a co-catalyst, giving silyl enol ethers in high yields.
Photochemical Cycloaddition of C78 with Disilirane
Authors: Han Aihong , Wakahara Takatsugu , Maeda Yutaka , Niino Yasuyuki , Akasaka Takeshi , Yamamoto Kazunori , Kako Masahiro , Nakadaira Yasuhiro , Kobayashi Kaoru , Nagase Shigeru 
Published: April 2003

Abstract
The photochemical cycloaddition of C78(C2v+D3) with disilirane 1 only gave the adducts of C78(C2v). The D3 isomer of C78 did give no adduct with 1. The two mono-adducts were firstly isolated by a multi-stage HPLC, and characterized on the basis of the spectroscopic data. The electrochemical properties were also investigated by means of differential pulse voltammetry.
Variation of Susceptibility as Observed by Magnetic Levitation of Liquid Droplets
Authors: Fujita Toma , Dushkin Ceco , Nawa Masayoshi , Nakabayashi Seiichiro 
Published: April 2003

Abstract
The magnetic force is applied for the precisely controlled levitation of salt-containing water droplets in oil phase. This levitation phenomena analyses were achieved by the analytical calculation of the inhomogeneous space distribution of the field and force in the bore of a vertical superconducting magnet. The tiny effects on the droplet position are explained as variation of the diamagnetic susceptibility in the course of levitation.
Separation of copper(II) and aluminium(III) from fresh waters by solid phase extraction on a complexing resin column
Authors: Pesavento Maria , Biesuz Raffaela , Alberti Giancarla , Sturini Michela 
Published: April 2003

AbstractThe solid‐phase extraction (SPE) of copper(II) and aluminium(III) from fresh waters on an ion‐exchange complexing resin containing iminodiacetic groups (Chelex 100) has been examined. Quantitative recovery of the metal ions was related to the breakthrough profile that, for some samples, could not be evaluated directly. A method is suggested for evaluation, instead, of the sorption curves, on the basis of passing different volumes of sample through the column. This enables evaluation of important properties, for instance the central point of the breakthrough curve, Vf. The column used was a small one, containing 0.10 g dry Chelex 100. The metal ion was eluted with a small volume of acid solution, 10 mL of 0.5 mol L–1 HNO3; this resulted in good preconcentration factors. For copper(II) it was found that fresh waters of similar composition could have different Vf in the same column. This was ascribed to different reaction coefficients (αM(I)) of copper(II) in the considered samples, which affects Vf. By use of the proposed SPE procedure it is possible to evaluate the reaction coefficient of copper(II). The values of αM(I) for two different drinking waters at pH 7.7 were found to be 3.70×1012 and less than 4.40×1011. Similar results were obtained for aluminium(III).
Isoelectric focusing in soil science
Authors: Alianiello Francesco 
Published: April 2003

AbstractApplications of isoelectric focusing (IEF) in soil science are illustrated. The materials studied, i. e. humic substances and organic fertilisers, and their behaviour when subjected to IEF are briefly described. Preliminary studies carried out on soil indicate a relation between the isoelectric point and molecular weight, and a connection with humification has been hypothesised; therefore, assessment of soil conditions could be an application of IEF. Another application is evaluation of the stabilisation of organic fertilisers. Finally, IEF can be used to distinguish different organic matrices, as such and in mixtures with mineral fertilisers.
Nitrated polynuclear aromatic hydrocarbons in ambient air in Italy. A brief overview
Authors: Cecinato Angelo 
Published: April 2003

AbstractWhen nitrated polynuclear aromatic hydrocarbons (NPAH) were recognised as long‐term toxic compounds and were also identified in several anthropogenic emissions and among the by‐products of photochemical smog they became objects of investigation in ambient air in both polluted and clean environments. In Italy the first investigations focussing on atmospheric NPAH were performed in the early eighties and encompassed both the canyon streets and dwelling areas of Rome. Because NPAH were indicated as markers of vehicle emission, new investigations were performed in other cities and also in rural and (nominally) unpolluted locations. In general, the first measurements of NPAH were episodic and could not be assumed to be strictly representative of the sites investigated. In contrast, nowadays consistent data bases on NPAH have been built up and are discussed in the technical literature, so that both neat concentrations and the yearly timed variation of the most important NPAH congeners have been measured in Italian air. Although concentrations of NPAH in air are usually much lower than those of PAH, owing to their very high potency in inducing mutations and tumours NPAH are regarded as having an important health impact on populations living in Italian urban areas. In this regard the genotoxicity of atmospheric aerosols is partly associated with nitrofluoranthenes and nitropyrenes whereas nitronaphthalenes and methylnitronaphthalenes seem to contribute to that of the gaseous organic fraction. Several civic and regional administrations are introducing control of atmospheric NPAH among ways of improving air quality in cities.
Preparation of Silk‐Like Fibers Designed by Self‐Assembled Ionic Polypeptides
Authors: Hachisu Masakazu , Ohkawa Kousaku , Yamamoto Hiroyuki 
Published: April 2003

AbstractNatural protein fibers, such as silk, having high‐performance characteristics have been important materials in biopolymer research. This article reports the development of a silk‐like extensible poly(α,L‐amino acid) fiber inspired by self‐assembly of polypeptides in living systems. Electrostatic interaction was employed as the driving force for building the fiber, and we succeeded in spinning the fiber from an aqueous solution interface between poly(α,L‐lysine) (PLL) and poly(α,L‐glutamic acid) (PLG). When the PLL/PLG fiber was formed, the conformations of PLL and PLG were changed from random to β‐structures. A remarkable feature of the PLL/PLG fiber is the high extensibility. Mechanical stretching of the PLL/PLG fiber resulted in a change from an extensible fiber to a rigid and strong fiber. These features depend on the molecular conformation and the deviation in the amino acid composition of the PLL/PLG fibers. This concept and the poly(α,L‐amino acid) fibers themselves allow the production of new protein fibers and aid the development of the science of protein folding as well as giving insight into the noncovalent interactions involved in self‐assembly.SEM micrograph showing that the surface of the stretched fiber is smooth.magnified imageSEM micrograph showing that the surface of the stretched fiber is smooth.
Lipschitz estimates for generalized commutators of fractional integrals with rough kernel
Authors: Lu Shanzhen , Zhang Pu 
Published: April 2003

AbstractLet $ T ^{A} _{\Omega, \alpha} $ (0 < α < n) be the generalized commutator generated by fractional integral with rough kernel and the m–th order remainder of the Taylor formula of a function A. In this paper, the (Lp, Lr) (r > 1) boundedness, the weak (L1, Ln/(n–α–β)) boundedness and the (Lp, Ḟβ, ∞p) boundedness of $ T ^{A} _{\Omega, \alpha} $ are discussed, when DγA belongs to the Lipschitz function spaces.
Synthesis, Characterization, and AC Impedance Properties of a Novel Ion‐Conducting Polymer
Authors: Pietschnig Rudolf , Langkau Tatjana , Neuser Rolf , Hipler Frank , Hambrock Julia , Schäfer Sven 
Published: April 2003

AbstractThis paper describes the preparation and characterization of a novel ion‐conducting polymeric material (2). The backbone consists of alternating alkenylidene and sulfanylidene units with adjacent hydroxy groups. Fitting of the experimental impedance data of 2 in a Bode plot reveals a conductivity of 6.6 × 10−2 S · cm−1 and a capacitance of 2.2 × 10−5 F at room temperature. The deuterated derivative of 2 shows significantly lower conductivity, suggesting that the conductivity of 2 can be attributed to proton migration.Bode plot of fresh 2; experimental vs simulated; equivalent circuit (R(RQ)).magnified imageBode plot of fresh 2; experimental vs simulated; equivalent circuit (R(RQ)).
Synthesis and Characterization of Long‐Chain‐Branched Polyolefins with Metallocene Catalysts: Copolymerization of Ethylene with Poly(ethylene‐co‐propylene) Macromonomer
Authors: Kolodka Edward , Wang Wen‐Jun , Zhu Shiping , Hamielec Archie 
Published: April 2003

AbstractPoly(ethylene‐co‐propylene) macromonomer (EPM) was synthesized in a high‐temperature continuous stirred tank reactor (CSTR) with [C5Me4(SiMe2NtBu)]TiMe2 (CGC‐Ti) as the catalyst system. PE samples with EPM long chain branching (LCB) were produced by semi‐batch copolymerization of ethylene and EPM with CGC‐Ti. The LCB frequencies were up to 21.8 EPM side chains per PE backbone. The effects of temperature and ethylene pressure on the degree of EPM grafting and catalyst activity were examined.
Incorporation of EPM into a growing PE chain forming an LCB polymer.magnified imageIncorporation of EPM into a growing PE chain forming an LCB polymer.
Synthesis and Characterization of α,ω‐Heterofunctional Poly(ethylene oxide) Macromonomers
Authors: Yilmaz Faruk , Cianga Ioan , Ito Koichi , Senyo Takamichi , Yagci Yusuf 
Published: April 2003

AbstractA novel α,ω‐heterofunctional poly(ethylene oxide) (PEO) macromonomer possessing methacryloyl and thienyl end groups was prepared by ring‐opening polymerization of ethylene oxide initiated by potassium thienylethoxide and termination of the living PEO ends with methacryloyl chloride. Incorporation of methacryloyl and thienyl groups was confirmed by free‐radical and oxidative polymerization processes, respectively, and by means of 1H NMR analysis.magnified image
The formation of metal clusters in solution and on biopolymers investigated by first‐principles molecular dynamics
Authors: Colombi Ciacchi L. , De Vita A. , Seidel R. , Mertig M. , Pompe W. 
Published: April 2003

AbstractWe investigate the molecular mechanisms of platinum cluster nucleation and growth in solution and on biopolymers by means of first‐principles molecular dynamics. In contrast with a classical picture where clusters nucleate by aggregation of metallic Pt(0) atoms, we find that Pt–Pt bonds can form between dissolved Pt(II) complexes already after a single reduction step. Furthermore, we observe that small clusters grow by addition of unreduced PtCl2(H2O)2complexes, consistently with an autocatalytic growth mechanism. Moreover Pt(II) ions covalently bound to biopolymers are found to act as preferred nucleation sites for the formation of clusters. This is a consequence of the strong donor character of the organic ligands which induce the formation of stronger metal‐metal bonds than those obtained in solution. In fact, in metallization experiments we obtain a clean and purely heterogeneous metallization of single DNA molecules leading to thin and uniform Pt cluster chains extended over several microns.
ℋ︁‐matrices for the convection‐diffusion equation
Authors: Le Borne S. 
Published: April 2003

AbstractHierarchical matrices (ℋ︁‐matrices) provide a technique for the sparse approximation of large, fully populated matrices. This technique has been shown to be applicable to stiffness matrices arising in boundary element method applications where the kernel function displays certain smoothness properties. The error estimates for an approximation of the kernel function by a separable function can be carried over directly to error estimates for an approximation of the stiffness matrix by an ℋ︁‐matrix, using a certain standard partitioning and admissibility condition for matrix blocks. Similarly, ℋ︁‐matrix techniques can be applied in the finite element context where it is the inverse of the stiffness matrix that is fully populated. Here one needs a separable approximation of Green's function of the underlying boundary value problem in order to prove approximability by matrix blocks of low rank. Unfortunately, Green's function for the convection‐diffusion equation does not satisfy the required smoothness properties, hence prohibiting a straightforward generalization of the separable approximation through Taylor polynomials. We will use Green's function to motivate a modification in the (hierarchical) partitioning of the index set and as a consequence the resulting hierarchy of block partitionings as well as the admissibility condition. We will illustrate the effect of the proposed modifications by numerical results.
A short overview of ℋ︁2‐matrices
Authors: Börm Steffen , Hackbusch Wolfgang 
Published: April 2003

Abstractℋ︁2‐matrices are a refined version of hierarchical matrices, which in turn are based on the panel‐clustering approach for approximating certain integral operators. Their main advantage, as compared with their predecessors, is that the associated algorithms are of significantly lower complexity while providing the same order of accuracy. Under certain conditions, it is even possible to reach optimal complexity.
ADOL‐C: Automatic Differentiation Using Operator Overloading in C++
Authors: Walther Andrea , Griewank Andreas , Vogel Olaf 
Published: April 2003

AbstractIn this paper, we present two strategies for the implementation of Automatic Differentiation (AD) based on the operator overloading facility in C++. Subsequently, we describe the capabilities of the AD‐tool ADOL‐C that applies operator overloading to differentiate C‐ and C++‐code. Finally, we discuss some applications of ADOL‐C.
Automatic Balancing of the Unsymmetrical Rigid Rotor
Authors: Ryzhik B. , Duckstein H. , Sperling L. 
Published: April 2003

AbstractThe paper is devoted to the investigation of an automatic balancing device for rigid rotors. It presents some new results concerning automatic balancing, namely the effect of partial unbalance compensation and reduction of vibrations in the region after the first critical speed.