bluuebunny/crossref_metadata_2025 huggingface dataset:
A Conjugate Addition of Arylboronic Acids to α,β-Unsaturated Carbonyl Compounds Catalyzed by 2β-CD-[Rh(OH)(cod)]2 or [RhCl(cod)]2 in a Single Aqueous Medium
Authors: Itooka Ryoh , Iguchi Yuki , Miyaura Norio
Published: March 2003

The rhodium-catalyzed conjugate addition of tolylboronic acid to α,β-unsaturated ketones, esters or amides was carried out in water. [RhCl(cod)]2 and 2β-cyclodextrin-[Rh(OH)(cod)]2 complexes were found to catalyze the reaction efficiently in a single aqueous medium.
l-Threoninol as a Chiral Linker of Azobenzene for the Effective Photo-regulation of DNA Triplex Formation
Authors: Takarada Tohru , Tamaru Daisuke , Liang Xingguo , Asanuma Hiroyuki , Komiyama Makoto
Published: March 2003

An azobenzene was enantioselectively attached to the 5′-end of oligo(T) through d- or l-threoninol. Photo-isomerization of azobenzene, tethered on l-threoninol, induced much larger change of melting temperature of triplex formation than did that on the d-form.
Adsorption-Induced Self-Organization of Calix[4]arene on Au(111) Surfaces
Authors: Sakai Takemitu , Ohira Akihiro , Sakata Masayo , Hirayama Chuichi , Kunitake Masashi
Published: March 2003

The construction and sub-molecular visualization of a self-organized adlayer of calix[4]arene on a Au(111) surface were achieved by potential-controlled adsorption and in situ STM. In situ STM images revealed that the self-organized molecular array consisted of a calix[4]arene dimer. The two molecules in a cone conformation with a sideways orientation were connected in a “head to head” orientation between the hydroxy groups.
Crystal Structure Analysis of a Hexatungstate by a High-Energy X-ray Diffraction Experiment Using an Imaging Plate Weissenberg Camera at the BL04B2 Beamline of SPring-8
Authors: Ozeki Tomoji , Kusaka Katsuhiro , Honma Noritaka , Nakamura Yuji , Nakamura Setsuko , Oike Shunsuke , Yasuda Nobuhiro , Imura Hiroyuki , Uekusa Hidehiro , Isshiki Maiko , Katayama Chuji , Ohashi Yuji
Published: March 2003

An imaging plate Weissenberg camera was installed in the BL04B2 beamline of SPring-8 aiming at automated crystal structure determinations of small molecules. Since this beamline is designed to provide X-rays with the energies higher than 37 keV (λ < 0.33 Å), this camera is advantageous in crystal structure analyses of heavily X-ray absorbing materials. The title crystal structure analysis led to precise positional parameters and well-behaved displacement parameters not only for heavy atoms but also for light atoms.
Sodium Perborate Catalyzed Selective Transesterification of β-Keto Esters under Neutral Conditions
Authors: Bandgar B P , Sadavarte V S , Uppalla L S
Published: March 2003

Transesterification of β-keto esters with various alcohols has been carried out using sodium perborate as an inexpensive catalyst under neutral conditions. The effectiveness of the protocol is manifested in its selectivity towards β-keto esters whereas other esters are found to be unreactive under these reaction conditions.
Fe-MCM-41 for Selective Epoxidation of Styrene with Hydrogen Peroxide
Authors: Zhang Qinghong , Wang Ye , Itsuki Satoko , Shishido Tetsuya , Takehira Katsuomi
Published: March 2003

Fe-MCM-41 prepared by direct hydrothermal synthesis catalyzes the epoxidation of styrene with diluted H2O2. The selectivity to styrene oxide reached 67% at styrene conversion of 17% over the catalyst with Si/Fe ratio of 86, which is better than that obtained over TS-1 or a titanium-incorporated silica.
Green High Energy Density Material, N2H2O
Authors: Ding Yi-hong , Inagaki Satoshi
Published: March 2003

We proposed a new concept “green high energy density material” (HEDM) and designed some N2H2O isomers, i.e. oxadiaziridines (1a, 1b), diimide N-oxides (2a, 2b), hydroxydiimides (4a, 4b) and nitrosoamide (5). These isomers satisfy the following conditions: (i) they have high energy densities; (ii) they have considerable kinetic stability; (iii) their green channels are favored more than non-green channels; and (iv) they have high possibility to be actually synthesized for practical use. The very high energy densities of oxadiaziridines (1a, 1b) and the outstanding kinetic stability of diimide N-oxides (2a, 2b) are strongly encouraging the first realization of green HEDM.
Highly Active Delaminated Ti-MWW for Epoxidation of Bulky Cycloalkenes with Hydrogen Peroxide
Authors: Nuntasri Duangamol , Wu Peng , Tatsumi Takashi
Published: March 2003

A novel titanosilicate, prepared by the partial delamination of acid-treated Ti-MWW, possesses an extremely high specific surface area and proves to be a selective and active liquid-phase oxidation catalyst for bulky alkenes.
Novel Sulfoalkoxylated Polyimide Membrane for Polymer Electrolyte Fuel Cells
Authors: Yin Yan , Fang Jianhua , Kita Hidetoshi , Okamoto Ken-ichi
Published: March 2003

A novel sulfoalkoxylated diamine, 2,2′-bis(3-sulfopropoxy)benzidine (2,2′-BSPB) was successfully synthesized and the sulfonated polyimide was prepared from this diamine and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). The resulting polyimide membrane displayed high proton conducting performance and excellent water stability, indicating potential application for polymer electrolyte fuel cells.
Diastereoselective Formation of Metallaphosphacyclo Iridium(III) Complexes from Phosphoranido Iridium(III) Complex
Authors: Kajiyama Kazumasa , Nakamoto Atsushi , Miyazawa Shunsuke , Miyamoto Takeshi Ken
Published: March 2003

A phosphoranido iridium(III) complex is prepared by the reaction of Cp*IrCl2(PMe3) with lithium phosphoranide generated from a P–H spirophosphorane bearing two 8-oxy-1-naphthyl groups. The complex is thermally converted into metallaphosphacyclo complexes with diastereoselectivity.
p-Doping of Poly(3-hexylthiophene-2,5-diyl) with Sulfonic Acids and Oxygen Related to Self-doping of Sulfonated Polythiophenes
Authors: Yamamoto Takakazu
Published: March 2003

Poly(3-hexylthiophene-2,5-diyl), P3HexTh, was p-doped by sulfonic acids such as CH3SO3H in the presence of O2. In the case of regioregular head-to-tail type P3HexTh, molecular assembly took place prior to the p-doping. Tetramer and pentamer of thiophene underwent similar oxidation.
Crossed Aldol Reaction Using Polymer-bound Lithium Amides
Authors: Seki Atsushi , Takizawa Youichi , Ishiwata Fusae , Asami Masatoshi
Published: March 2003

Polymer-bound lithium amides were used in an aldol reaction. The introduction of a spacer between the polymer backbone and the reactive site was important to enhance yields of the aldol products. The polymer-bound reagent was repeatedly used in the same reaction after the conversion to the lithium amide.
Phototransamidation as a Method for the Synthesis of N-Glycosyl Asparagines
Authors: Vízvárdi Kristóf , Kreutz Christian , Davis Alexander S , Lee Vincent P , Philmus Benjamin J , Simo Ondrej , Michael Katja
Published: March 2003

N-Glycosyl asparagines were synthesized by a mild photochemical coupling method in which a photoreactive amide of an aspartic acid’s β-carboxyl group is condensed with an aminosaccharide. Upon excitation, the γ-carbon becomes susceptible to nucleophilic attack and the obtained N-glycosyl asparagines, which may be useful building blocks for the synthesis of N-glycopeptides and neoglycopeptides, are generated in good yields.
Synthesis of a Core Trisaccharide as a Versatile Building Block for N‐Glycans and Glycoconjugates
Authors: Unverzagt Carlo
Published: March 2003

N‐Linked oligosaccharides from glycoproteins (N‐glycans) can be conveniently assembled with a building block approach. A protected form of the core trisaccharide (β‐mannosyl chitobiose) was identified as a key building block. The chitobiose part of the core trisaccharide was built from a glycosyl fluoride, which served as a precursor for the reducing GlcNAc azide and the inner GlcNAc moiety. β‐Mannosylation was accomplished at the trisaccharide stage by intramolecular inversion of a β‐glucosyl chitobiose. The benzylidene protection of the β‐mannoside and the azido group at the reducing end of the core trisaccharide allow modular synthesis of N‐glycans and their glycoconjugates.
Homogeneous Catalysts Supported on Soluble Polymers: Biphasic Sonogashira Coupling of Aryl Halides and Acetylenes Using MeOPEG‐Bound Phosphine–Palladium Catalysts for Efficient Catalyst Recycling
Authors: Köllhofer Axel , Plenio Herbert
Published: March 2003

The Sonogashira coupling of various aryl bromides and iodides with different acetylenes was studied under biphasic conditions with soluble, polymer‐modified catalysts to allow the efficient recycling of the homogeneous catalyst. For this purpose, several sterically demanding and electron‐rich phosphines of the type RPPR2 were synthesised. They are covalently linked to a monomethyl polyethylene glycol ether with a mass of 2000 Dalton (RP=MeOPEG2000) RPPR2: PR2=CH2C6H4CH2P(1‐Ad)2, C6H4‐P(1‐Ad)2, C6H4‐PPh2. To couple aryl iodides and acetylenes, the catalyst [(MeCN)2PdCl2]/2 RP‐C6H4‐PPh2 was used in CH3CN/Et3N/n‐heptane (5/2/5). The combined yields of coupling product over five reaction cycles are between 80–95 %. There is no apparent leaching of the catalyst into n‐heptane, as evidenced by 1H NMR spectroscopy. The new catalyst [(MeCN)2PdCl2]/2 (1‐Ad)2PBn can be used for room‐temperature coupling of various aryl bromides and acetylenes in THF with HNiPr2 as a base. A closely related catalyst Na2[PdCl4]/2 RP‐CH2C6H4CH2P(1‐Ad)2 linked to the polymer was used to couple aryl bromides and acetylenes in DMSO or DMSO/n‐heptane at 60 °C with 0.5 mol % Na2[PdCl4], 1 mol % RPPR2 and 0.33 mol % CuI. The combined yield of coupling products over five cycles is always greater than 90 %, except for sterically hindered aryl bromides. The determination of the turnover frequency (TOF) of the catalyst indicates only a small decrease in activity over five cycles. Leaching of the catalyst into the product containing n‐heptane solution could not be detected by means of 1H NMR and TXRF; this is indicative of >99.995 % catalyst retention in the DMSO solvent.
The Influence of σ and π Acceptors on Two‐Photon Absorption and Solvatochromism of Dipolar and Quadrupolar Unsaturated Organic Compounds
Authors: Strehmel Bernd , Sarker Ananda M. , Detert Heiner
Published: March 2003

Two‐photon absorption cross sections δ and solvatochromic properties were determined for a series of quadrupolar and dipolar compounds by using femtosecond excitation in the spectral range between 710 and 960 nm. The compounds investigated were distyrylbenzenes and polyenes bearing appropriate π or σ acceptors. The δ values for the centrosymmetric compounds trans,trans‐1,4‐bis[2‐(2′,5′‐dihexyloxy)phenylethenyl]‐2,3,5,6‐tetrafluorobenzene (6), trans,trans‐1,4‐bis[2‐(4′‐dibutylamino)phenylethenyl]‐2,3,5,6‐tetrafluorobenzene (2), trans,trans‐1,4‐bis[2‐(4′dimethylamino)phenylbutadienyl]‐2,3,5,6‐tetrafluorobenzene (7), trans,trans‐1,4‐bis[2‐(4′‐dimethylamino)phenylethenyl]‐2,5‐dicyanobenzene (4) and trans,trans‐1,4‐bis[2‐(4′‐dimethylamino)phenylethenyl]‐2‐propylsulfonyl‐5‐(2‐ethylhexyl)sulfonylbenzene (3) are on the order of 600, 1400, 1700, 3000, and 4100×10−50 cm4 s photon−1, respectively. The corresponding dipolar compounds trans‐2‐(4′‐dimethylaminophenyl)ethenyl‐2,3,4,5,6‐pentafluorobenzene (8), trans‐4‐(4′‐dimethylaminophenyl)butadienyl‐2,3,4,5,6‐pentafluorobenzene (9), trans‐6‐(4′‐dimethylaminophenyl)hexatrienyl‐2,3,4,5,6‐pentafluorobenzene (10) were additionally investigated. All centrosymmtric compounds are good fluorescent materials, while the dipolar chromophores 8–10 exhibit low fluorescence quantum yields. Solvatochromism was also observed for the fluorophores 2–10 as a result of intramolecular charge transfer (ICT). Furthermore, a reasonable correlation was obtained between measured and calculated δ. Quantum chemical calculations were performed by using the INDO Hamiltonian with a MRDCI scheme. The results show that the sum over states (SOS) expression for the second hyperpolarizability γ is appropriate to describe the mechanism of two‐photon absorption. Mechanistic investigations of quadrupolar compounds showed that the energy of the two‐photon excited state is higher than S1.
Photoluminescence Intensity Fluctuations and Electric‐Field‐Induced Photoluminescence Quenching in Individual Nanoclusters of Poly(phenylenevinylene)
Authors: Scheblykin Ivan , Zoriniants George , Hofkens Johan , De Feyter Steven , Van der Auweraer Mark , De Schryver Frans C.
Published: March 2003

Substantial fluctuations of the fluorescence intensity have been detected for single clusters of poly(phenylenevinylene) containing more than 75 polymer chains or 30 000 monomer units. To the best of our knowledge, this is the first time such fluctuations (which resemble the “blinking” effect in single‐molecule fluorescence) have been reported for such a large molecular ensemble containing several macromolecules. Together with the distinct jumps, smooth fluctuations of the fluorescence intensity, with characteristic times from milliseconds to seconds, were observed. This fact distinguishes the fluorescence behaviour of the polymer clusters from that of other multichromophoric systems such as the single chains of conjugated polymers reported in the literature. The consecutive or simultaneous switching of one or several emitting sites from the “on” to “off” state does not explain the character of the fluctuations observed. We suggest that the quenching of the light‐emitting exciton by a long‐lived species, such as, for example, polarons, plays an important role in these unusual fluctuations. Electric field induced fluorescence quenching differs significantly for different clusters. It is proposed that this fluorescence was mainly quenched by polarons injected from the electrodes in the presence of an electric field. The specific behaviour of each cluster is explained by suggesting a different position of the clusters with respect to the electrodes.
A miniaturized matrix‐assisted laser desorption/ionization time of flight mass spectrometer with mass‐correlated acceleration focusing
Authors: English Robert D. , Cotter Robert J.
Published: March 2003

Mass correlated acceleration (MCA) has now been integrated into a 4 in (10.2 cm) matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometer to achieve high resolving power across a broader mass range, without sacrificing detection of higher mass ions. The goal was to combine MCA with a custom‐built miniaturized instrument such as those that might be used for field‐portable applications. Unlike other pulsed extraction methods, MCA is not mass dependent and mass spectra can be achieved with a single tuning of instrument parameters. Additionally, the multi‐channel recording advantage is better realized because ions of all masses can be brought into focus simultaneously. The MCA dual‐stage ion source compensates dynamically for the mass dependence by incorporating an extraction pulse region followed by an acceleration region that contains a time‐dependent waveform correlated with mass. The technique was validated with applications in peptide mixtures and protein digestions. Diagnostic studies for the instrument include m/z range and limits of detection. Copyright © 2003 John Wiley & Sons, Ltd.
Toughness Optimization of SBR Elastomers – Use of Fracture Mechanics Methods for Characterization
Authors: Reincke Katrin , Grellmann Wolfgang , Lach Ralf , Heinrich Gert
Published: March 2003

Elastomer materials are used in a wide application range and subjected to different loading from which failure of the material results. Because this failure is caused by initiation and propagation of cracks, the application of fracture mechanics methods for the assessment of the material is obvious. A short summary of the methods of technical fracture mechanics including possibilities of determination of crack resistance curves is given. Vulcanizates on the basis of SBR 1500 with various sulfur and carbon black contents were investigated. For describing the crack initiation and crack propagation behavior, several fracture mechanics examination methods were applied. Tear‐analyzer results were used to assess the crack propagation behavior under fatigue‐like loading conditions. Furthermore, for the characterization of the crack resistance of the materials under impact‐like loading conditions, instrumented tensile‐impact tests were performed. To obtain information about the initiation and propagation of a stable crack, quasi‐static fracture mechanics tests were applied. The results of the several tests are discussed in dependence on sulfur and carbon black contents. We found a non‐monotonous behavior of the toughness as a function of carbon black loading. An explanation is given in connection with a percolation‐like transition in filler morphology on larger length scales.

Schematic crack propagation curve for characterizing the fatigue behavior of the vulcanizates recorded in a TFA test.

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Schematic crack propagation curve for characterizing the fatigue behavior of the vulcanizates recorded in a TFA test.
Insertion of Copper(II)/Schiff‐Base Complexes with NLO Properties into Commercial Polycarbonates by Thermal Processes
Authors: Scamporrino Emilio , Bazzano Sebastiano , Vitalini Daniele , Mineo Placido
Published: March 2003

The preparation of a bisphenol‐A carbonate copolymer, containing Cu‐diimine units with nonlinear optical (NLO) properties, and its MALDI‐TOF mass spectrometric characterization are reported. Contrary to the usual synthetic method, NLO groups were inserted directly into a commercial polycarbonate by prolonged heating at 250 °C. This innovative procedure allows to obtain a Cu/diimine‐containing polymer of high molecular weight.

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A time‐based reservation scheme for managing handovers in satellite systems
Authors: Boukhatem L. , Gaïti D. , Pujolle G.
Published: March 2003

This paper proposes a Time‐based Channel Reservation Algorithm (TCRA) suitable for managing handover and call admission control procedures in future mobile satellite systems. These systems are characterized by a high rate of handover attempts which can degrade significantly their performance. Therefore, we propose TCRA, a scheme which guarantees a null handover failure probability by managing the channel through a reservation strategy in the cells to be crossed by the user. Based on the feature that the satellite motion is predictable and deterministic, the scheme tries to maximize the channel utilization and enables the system to handle the most important number of users. The performance of the TCRA scheme has been examined by simulations and compared to the Guaranteed Handover (GH) scheme. The results show the behaviour of the algorithm and its performance. Copyright © 2003 John Wiley & Sons, Ltd.
Ligand‐based computer‐aided pesticide design. A review of applications of the CoMFA and CoMSIA methodologies
Authors: Bordás Barna , Kőmíves Tamás , Lopata Antal
Published: March 2003

An overview is given of the CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indices analysis) methodologies that are established ligand‐based molecular design tools widely used by medicinal and pesticide chemists. In the absence of a three‐dimensional structure of the target biopolymer, CoMFA and CoMSIA often provide a practical solution to an otherwise intractable problem of proper characterization of ligand–receptor interactions. These techniques are especially important in agrochemistry, where the number of known molecular structures of pesticide targets is limited. The use of CoMFA and CoMSIA in the agrochemical field for modelling the interactions of insecticides, fungicides, herbicides and herbicide safeners with their target binding sites is illustrated by using some selected published work. The CoMFA and CoMSIA models developed have been used successfully to map the properties of unknown receptors, construct hypotheses for ligand–receptor interactions, optimize lead structures, design novel active compounds, and predict biological activities. The application of CoMFA by the present authors for deriving a binding site hypothesis for dichloroacetamide‐type herbicide safeners is described in somewhat more detail.

© 2003 Society of Chemical Industry
Standard and Swedish variant types of the hybrid alder Phytophthora attacking alder in Hungary
Authors: Nagy Zoltán Á , Bakonyi József , Érsek Tibor
Published: March 2003

A new Phytophthora disease of common alder (Alnus glutinosa) similar to that previously reported in several countries in Europe has been observed in Hungary. Based on these earlier studies, the alder Phytophthora was considered likely to be a hybrid between P cambivora and a P fragariae‐like species: across Europe a range of new alder Phytophthora is spreading that comprise a range of heteroploid hybrids including a ‘standard’ hybrid type and several other hybrid types termed ‘variants’. Phenotypic and molecular features of the pathogen in Hungary were characterised and compared with isolates from elsewhere. The morphologies of five isolates from one region (Hévíz) resembled the common, ‘standard’ type, whereas the three isolates from another region (Hanság) exhibited traits similar to those of one of the ‘variant’ types, ie the Swedish ‘variant’. Molecular markers of these two groups of Hungarian isolates also represented a good fit to those of the standard type and the Swedish variant, respectively. Isozyme patterns and profiles of restriction fragments of the entire internal transcribed spacer (ITS) region or mitochondrial DNAs and of RAPD‐PCR products did not differ within a group, but distinct polymorphisms were exhibited between the two groups of isolates. Southern analysis of random amplified polymorphic DNA (RAPD) revealed the homologous nature of co‐migrating bands of P cambivora and the isolates of alder Phytophthora. Furthermore, restriction fragment profiles of the ITS region of ribosomal DNAs and the mtDNAs were consistent with reported biparental origin of alder Phytophthora. The hybrid status of these continuously evolving pathogens raises many issues and challenges concerning efficient control measures.

© 2003 Society of Chemical Industry
Application of Quantitative Analytical Electron Microscopy to the
Mineral Content of Insect Cuticle
Authors: Rasch Ron , Cribb Bronwen W. , Barry John , Palmer Christopher M.
Published: March 2003

Quantification of calcium in the cuticle of the fly larva
Exeretonevra angustifrons was undertaken at the micron scale
using wavelength dispersive X-ray microanalysis, analytical standards,
and a full matrix correction. Calcium and phosphorus were found to be
present in the exoskeleton in a ratio that indicates amorphous calcium
phosphate. This was confirmed through electron diffraction of the
calcium-containing tissue. Due to the pragmatic difficulties of
measuring light elements, it is not uncommon in the field of entomology
to neglect the use of matrix corrections when performing microanalysis
of bulk insect specimens. To determine, firstly, whether such a
strategy affects the outcome and secondly, which matrix correction is
preferable, phi-rho (z) and ZAF matrix corrections were contrasted with
each other and without matrix correction. The best estimate of the
mineral phase was found to be given by using the phi-rho (z)
correction. When no correction was made, the ratio of Ca to P fell
outside the range for amorphous calcium phosphate, possibly leading to
flawed interpretation of the mineral form when used on its own.
Scavenging of Reactive Oxygen Species and Inhibition of the Oxidation of Low Density Lipoprotein by the Aqueous Extraction ofAnoectochilus formosanus
Authors: Shih Chun-Ching , Wu Yueh-Wern , Lin Wen-Chuan
Published: March 2003

The ability of Anoectochilus formosanus extract (AFE) to react with relevant biological oxidants was evaluated in this study. In addition, its effect on oxidation of low density lipoprotein (LDL) was investigated in vitro and in vivo. AFE could scavenge reactive oxygen species, such as superoxide anion and hydroxyl radical. The study of human LDL oxidation showed that AFE delayed oxidation in a concentration-dependent manner. In vivo studies also showed that oral administration of AFE delayed the oxidation of LDL from hyperlipidemic hamsters. The ability of AFE to scavenge free radicals suggests that it may be a promising anti-atherogenic agent.
EDITORIAL
Authors: DAYA SAGAR B. S. , BABU RAO C.
Published: March 2003

Natural systems undergo several morphological changes with time. To study spatio-temporal dynamics of such natural systems, and to further understand the morphological dynamical behaviors, various images that show several macro- and micro-level phenomena, acquired by various types of sensors need to be analyzed in spatio-temporal scales. Such analyses, to facilitate the researcher to model the spatio-temporal organization of a desired phenomenon, evidently require the robust procedures to extract specific error-free features from multiscale-temporal images represented in discrete space. Geometry and topology based features, such as edges of unique type and general type, are the indicators to record the changes that occur temporally. Extraction of such information is essential prerequisite to develop cogent models to understand the spatio-temporal organization.
AUTOMATIC SELECTION OF STRUCTURING ELEMENT FOR BENGALI NUMERAL RECOGNITION
Authors: CHANDA BHABATOSH , CHAUDHURI BIDYUT B.
Published: March 2003

How to select a structuring element for a given task is one of the most frequently asked questions in morphology. The present work tries to find a solution for a restricted class of problems, in the domain of shape classification. In this work an algorithm that extracts distinctive structure of each of a given set of objects, which can be used as the structuring elements for object classification system employing the hit-and-miss transformation, is proposed. The proposed algorithm is based on a new measure of local shape property. The method is used to develop a system for Bengali numeral recognition.
MATHEMATICAL MORPHOLOGY APPLIED TO COMPUTER GO
Authors: BOUZY BRUNO
Published: March 2003

This paper shows how mathematical morphological operators can be applied to computer go. On the one hand, mathematical morphology is a very powerful tool within image processing community. On the other hand, the Zobrist's model is well known within the computer go community for its "influence" recognition. We present a model, derived from the closing operator of mathematical morphology and from the Zobrist's model, which yields very good results for "territory" recognition. Moreover, we give efficient implementations of the dilation operator and territory recognition for computer go. This model was found when developing Indigo, our go playing program, and is now used with success in GnuGo, the go playing program of the Free Software Foundation.
AXIOMATIC G1-VERTEX ALGEBRAS
Authors: LI HAISHENG
Published: March 2003

Inspired by Borcherds' work on "G-vertex algebras," we formulate and study an axiomatic counterpart of Borcherds' notion of G-vertex algebra for the simplest nontrivial elementary vertex group, which we denote by G1. Specifically, we formulate a notion of axiomatic G1-vertex algebra, prove certain basic properties and give certain examples, where the notion of axiomatic G1-vertex algebra is a nonlocal generalization of the notion of vertex algebra. We also show how to construct axiomatic G1-vertex algebras from a set of compatible G1-vertex operators.
Adiabatic Intramolecular Hydrogen Atom Transfer in 2-[2-(2-Pyrrolyl)ethenyl]pyridine
Authors: Obi Masaki , Sakuragi Hirochika , Arai Tatsuo
Published: March 2003

2-[2-(2-Pyrrolyl)ethenyl]pyridine (3) forms an intramolecular hydrogen bond between the pyridine and pyrrole ring and undergoes one-way trans→cis isomerization on direct irradiation. Furthermore, cis isomer undergoes intramolecular hydrogen atom transfer to give a tautomer in the excited singlet state. Based on the experimental findings, effects of intramolecular hydrogen bond and the solvent on the photochemical behaviors of 3 were discussed.
Ga2O3/Al2O3 Prepared by Sol-Gel Method as a Highly Active Metal Oxide-Based Catalyst for NO Reduction by Propene in the Presence of Oxygen, H2O and SO2
Authors: Haneda Masaaki , Kintaichi Yoshiaki , Shimada Hiromichi , Hamada Hideaki
Published: March 2003

Ga2O3/Al2O3 prepared by sol-gel method showed excellent activity for the selective reduction of NO with propene in the presence of H2O, compared with Al2O3, Ga2O3 and impregnated Ga2O3/Al2O3. Its high activity was hardly influenced by the presence of SO2. It was suggested from the results of XPS studies that the presence of gallium oxide interacting strongly with alumina is responsible for the catalytic performance of Ga2O3/Al2O3.
Novel Discrete Structure of Oxalate-bridged Heteronuclear Cr(III)-Nd(III) Complex
Authors: Sakagami Narumi , Okamoto Ken-ichi
Published: March 2003

A novel chromium(III)-neodymium(III) heteronuclear complex has been obtained by utilizing unsym-cis-[Cr(eddp)(ox)]− as a building block. From the X-ray analysis, it is revealed that this complex is tetranuclear in which the Nd(III) ion is bridged by three oxalates in the three Cr(III) units and three water molecules forming a nine-coordinate tricapped trigonal-prism geometry.
Conducting Salts Composed of Selenium Analogues of TMET-TTP
Authors: Mori Takehiko , Ashizawa Minoru , Aragaki Masanobu , Murata Kyoji , Misaki Yohji , Tanaka Kazuyoshi
Published: March 2003

Selenium analogues of TMET-TTP (2-(4,5-bisthiomethyl-1,3-dithiol-2-ylidene)-5-(4,5-ethylenedithio-1,3-dithiol-2-ylidene)-1,3,4,6-tetrathiapentalene) 1b-d have been synthesized. The iodine salt (1b)4I3 exhibits moderately high conductivity (σrt=13S cm−1) with semiconducting temperature dependence, and the donor arrangement is θ-type. The present θ-type salt as well as TMET-TTP salts is located at the insulating limit in the universal phase diagram of θ-phases.
Hydrogen Transfer in Pt-Mo Heterodinuclear Hydride Complexes Promoted by Alkynes
Authors: Yasuda Toshiyuki , Fukuoka Atsushi , Hirano Masafumi , Komiya Sanshiro
Published: March 2003

Reactions of a Pt-Mo heterodinuclear hydride complex, (dpe)HPt-MoCp(CO)3 with alkynes at room temperature lead to facile reductive elimination giving HMoCp(CO)3 accompanied by the formation of Pt(alkyne)(dpe). When terminal alkynes are employed, further Markovnikov addition of HMoCp(CO)3 to the coordinated alkyne takes place to give new heterodinuclear alkenyl complexes (dpe)(μ-H2C=CR)Pt-MoCp(μ-CO)(CO).
Self-Assembly and X-ray Structure Determination of the Novel 2-D Layered Organic–Inorganic Hybrid Pb–X Compound: [PbX2(4,4′-bipy)]n (X = I, Br)
Authors: Shi Yu-Jun , Xu Yan , Zhang Yong , Huang Bin , Zhu Dun-Ru , Jin Chuan-Ming , Zhu Hao-Guo , Yu Zhi , Chen Xue-Tai , You Xiao-Zeng
Published: March 2003

Two novel organic–inorganic hybrid compounds, [PbI2(4,4′-bipy)]n (1) and [PbBr2(4,4′-bipy)]n (2), are synthesized by self-assembly. X-ray crystallography analysis shows that the [PbI2]n chains in 1 are linked by 4,4′-bipyridine to form a layer, via Pb–N bonding along the direction of the ‘b’ axis.
Electrochemically Regulated Iron Uptake and Release for Ferritin Immobilized on Self-Assembled Monolayer-Modified Gold Electrodes
Authors: Tominaga Masato , Taniguchi Isao
Published: March 2003

Horse spleen ferritin was immobilized on self-assembled monolayers (SAMs)-modified gold electrodes by electrostatic interaction. Electrochemically regulated iron uptake and release for the ferritin immobilized on the electrode was demonstrated.
Chemoselective Reduction of α-Imino Carbonyl Compounds into α-Amino Carbonyl Compounds with Titanium Tetraiodide
Authors: Shimizu Makoto , Sahara Tetsuya , Hayakawa Ryuuichirou
Published: March 2003

α-Imino carbonyl compounds are chemoselectively reduced with titanium tetraiodide to give α-amino carbonyl compounds in good to excellent yields
Multiple Fabrications of Crystalline CdS Thin Films from a Single Bath by EICD in Acidic Aqueous Solution of Cd2+ and Thiourea Complex
Authors: Yamaguchi Koichi , Mukherjee Pragati , Yoshida Tsukasa , Minoura Hideki
Published: March 2003

Multiple fabrications of crystalline CdS thin films have been realized by electrochemically induced chemical deposition (EICD) from a single acidic aqueous bath of stable Cd2+–thiourea complexes. Repeated depositions up to five times from the same bath have been proven to yield CdS thin films with essentially the same quality and thickness, owing to the absence of chemical decomposition of the precursor.
Surface-Mediated Solid Phase Reactions: A Simple and New Method for the Synthesis of α-Aminophosphonates under Solvent-Free Conditions
Authors: Kaboudin Babak
Published: March 2003

Alumina-supported ammonium formate was found to be an efficient reagent for the synthesis of 1-aminophosphonates from aldehydes and diethyl phosphite. This method is an easy, rapid and high-yielding reaction for the synthesis of 1-aminophosphonates.
A TiO2-Suspended Continuous Flow Photoreactor System Combined with the Separation of TiO2 Particles by Coagulation for the Photocatalytic Degradation of Dibutyl Phthalate
Authors: Hasegawa Kiyoshi , Ito Tomonori , Maeda Miyoko , Kagaya Shigehiro
Published: March 2003

A TiO2-suspended continuous flow photoreactor system combined with the separation of TiO2 particles by coagulation was applied for the photocatalytic degradation of dibutyl phthalate (DBP). The system enabled the efficient degradation of DBP and the continuous discharge of transparent water.
Mechanistic Study of the Ru(H)2(CO)(PPh3)3-Catalyzed Addition of C–H Bonds in Aromatic Esters to Olefins
Authors: Kakiuchi Fumitoshi , Ohtaki Hisashi , Sonoda Motohiro , Chatani Naoto , Murai Shinji
Published: March 2003

The reaction mechanism of the Ru(H)2(CO)(PPh3)3-catalyzed addition of C–H bonds in aromatic esters to olefins was studied by means of deuterium-labeling experiments and measurement of the 13C kinetic isotope effect. The deuterium-labeling experiment revealed a rapid equilibrium among the intermediates prior to the reductive elimination, and the 13C NMR kinetic isotope effect indicated that C–C bond formation is the rate-determining step in this reaction.
Polynucleotide Can Stabilize Nucleobase-appended Cholesterol Gels
Authors: Numata Munenori , Shinkai Seiji
Published: March 2003

The influence of added poly(A) or poly(C) on the gelation ability of uracil-appended cholesterol gelator was investigated. It was found that RNA-gelator complexes were formed in n-butanol solution. In particular, complementary poly(A) not only stabilized the gel system but also created the helical structure in the original gel phase.
Substituent Effect in Amine-CO2 Interaction Investigated by NMR and IR Spectroscopies
Authors: Yoon Sang Jun , Lee Huen
Published: March 2003

The donor property changes of amines by methyl or hydroxyl substituents were studied by NMR and FT-IR spectroscopies. This fundamental investigation can contribute for identifying CO2 absorption capacity of amine solution mainly due to electron releasing and withdrawing effects of substituents.
Crystallographic report: Bis(O‐methoxyethyldithiocarbonato)(4,7‐dimethyl‐1,10‐phenanthroline)cadmium(II)
Authors: Chen Danlin , Lai Chian Sing , Tiekink Edward R. T.
Published: March 2003

The structure of mononuclear Cd(S2COCH2CH2OCH3)2(4,7‐Me2phen) shows an N2S4 donor set about cadmium that defines a coordination geometry intermediate between octahedral and trigonal prismatic. Copyright © 2003 John Wiley & Sons, Ltd.
Crystallographic report: (2,9‐Dimethyl‐1,10‐phenanthroline)bis‐(N,N‐pyrrolidinedithiocarbamato)zinc(II) chloroform hemihydrate
Authors: Sing Lai Chian , Tiekink Edward R. T.
Published: March 2003

The mononuclear structure of Zn(S2C(N(CH2)2)4)2(2,9‐Me2‐1,10‐phen) shows monodentate coordination by the dithiocarbamate ligands and a distorted tetrahedral geometry for zinc, defined by an N2S2 donor set, results. Copyright © 2003 John Wiley & Sons, Ltd.
A Stereoselective and Short Total Synthesis of the Polyhydroxylated γ‐Amino Acid (−)‐Detoxinine, Based on Stereoselective Preparation of Dihydropyrrole Derivatives from Lithiated Alkoxyallenes
Authors: Flögel Oliver , Okala Amombo Marlyse Ghislaine , Reißig Hans‐Ulrich , Zahn Gernot , Brüdgam Irene , Hartl Hans
Published: March 2003

Based on our earlier results employing lithiated methoxyallene 2 as C3 building block and imines 3 for the synthesis of dihydropyrrole derivatives 5, we have investigated chiral imines 6, 10, and 15 as electrophilic components. Combined with lithiated alkoxyallenes, these imines provide the corresponding primary adducts and finally the dihydropyrrole derivatives 8, 12, 17, 20, and 22 in good yields and with high to excellent syn selectivities. This stereochemical outcome is interpreted as a result of α‐chelate control. Treatment with hydrochloric acid converted syn‐8 and syn‐12 into bicyclic compounds 9 and 13, whereas under more mildly acidic conditions adduct syn‐17 was transformed into diol syn‐18. The total synthesis of the uncommon γ‐amino acid (−)‐detoxinine could be achieved by starting from (S)‐malic acid, which was converted into imine 15 in four steps. Lithiated benzyloxyallene added to imine 15 and efficiently furnished the crucial dihydropyrrole derivative syn‐22. The hydrogenolysis of this compound did not directly provide the protected triol 29 as anticipated, but a stepwise protocol made the triol available in a fairly satisfactory manner. A second crucial step of the synthesis was the selective oxidation of 29, which could be achieved by employing platinum dioxide and oxygen. The resulting bicyclic lactone 30 was smoothly transformed into enantiopure (−)‐detoxinine. Thus, a fairly short synthesis of this natural product based on a lithiated alkoxyallene could be performed, demonstrating the potential of these intermediates for syntheses of interesting functionalized heterocyclic compounds.
Cover Picture: Direct Observation of Charge‐Transfer Reactions in Nanoscopic Test Tubes: Self‐Ionization in HNO3 Clusters (ChemPhysChem 3/2003)
Authors: Gebhardt Christoph R. , Witte Thomas , Kompa Karl L.
Published: March 2003

The cover picture shows schematically the release of charge carriers from a molecular cluster via cluster fragmentation caused by a surface collision. In the incoming cluster, which is neutral as a whole, a charge‐transfer reaction has previously generated equal numbers of positive‐ and negative‐charge carriers. The subsequent fragmentation now breaks the cluster apart and forms mass‐spectrometrically observable free charge carriers, represented here by the blue and the red sphere. Thus, surface collisions of large molecular clusters allow the direct observation of bulk‐phase charge‐transfer processes by mass spectrometry. Find out more in the communication by Gebhardt et al. on pp. 308–312.
Palladium‐Catalyzed SN1 Reactions of Secondary Benzylic Alcohols: Etherification, Amination, and Thioetherification
Authors: Miller Kimberly J. , Abu‐Omar Mahdi M.
Published: March 2003

The reaction of various secondary benzylic alcohols in the presence of PdII catalysts provides ethers in good to high yields. Unsymmetric ethers could also be obtained with good selectivity by coupling two different alcohols. Direct amination is observed with electron‐deficient anilines, and thioethers are prepared conveniently in high yields by the direct action of thiols on sec‐phenylethyl alcohol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Transitivity, flexibility, conjunctive representations, and the hippocampus. II. A computational analysis
Authors: Frank Michael J. , Rudy Jerry W. , O'Reilly Randall C.
Published: March 2003

A computational neural network model is presented that explains how the hippocampus can contribute to transitive inference performance observed in rats (Dusek and Eichenbaum, 1997. Proc Natl Acad Sci U S A 94:7109–7114; Van Elzakker et al., 2003. Hippocampus 12:this issue). In contrast to existing theories that emphasize the idea that the hippocampus contributes by flexibly relating previously encoded memories, we find that the hippocampus contributes by altering the elemental associative weights of individual stimulus elements during learning. We use this model to account for a range of existing data and to make a number of distinctive predictions that clearly contrast these two views. Hippocampus 2003;13:341–354. © 2003 Wiley‐Liss, Inc.
Protective role of melatonin in domoic acid‐induced neuronal damage in the hippocampus of adult rats
Authors: Ananth C. , Gopalakrishnakone P. , Kaur C.
Published: March 2003

Domoic acid (DA), a kainite‐receptor agonist and potent inducer of neurotoxicity, has been administered intravenously in adult rats in the present study (0.75 mg/kg body weight) to demonstrate neuronal degeneration followed by glial activation and their involvement with inducible nitric oxide synthase (iNOS) in the hippocampus. An equal volume of normal saline was administered in control rats. The pineal hormone melatonin, which protects the neurons efficiently against excitotoxicity mediated by sensitive glutamate receptor, was administered intraperitoneally (10 mg/kg body weight), 20 min before, immediately after, and 1 h and 2 h after the DA administration, to demonstrate its role in therapeutic strategy. Histopathological analysis (Nissl staining) demonstrated extensive neuronal damage in the pyramidal neurons of CA1, CA3 subfields and hilus of the dentate gyrus (DG) in the hippocampus at 5 days after DA administration. Sparsely distributed glial fibrillary acidic protein (GFAP)‐immunoreactive astrocytes were observed in the hippocampus at 4–24 h after DA administration and in the control rats. Astrogliosis was evidenced by increased GFAP immunoreactivity in the areas of severe neuronal degeneration at 5 days after DA administration. Along with this, microglial cells exhibited an intense immunoreaction with OX‐42, indicating upregulation of complement type 3 receptors (CR3). Ultrastructural study revealed swollen or shrunken degenerating neurons in the CA1, CA3 subfields and hilus of the DG and hypertrophied astrocytes showing accumulation of intermediate filament bundles in the cytoplasm were observed after administration of DA. Although no significant change could be observed in the mRNA level of iNOS expression between the DA‐treated rats and controls at 4–24 h and at 5‐day time intervals, double immunofluorescense revealed co‐expression of induced iNOS with GFAP immunoreactive astrocytes, but not in the microglial cells, and iNOS expression in the neurons of the hippocampal subfields at 5 days after DA administration. Expression of iNOS was not observed in the hippocampus of control rats. DA‐induced neuronal death, glial activation, and iNOS protein expression were attenuated significantly by melatonin treatment and were comparable to the control groups. The results of the present study suggest that melatonin holds potential for the treatment of pathologies associated with DA‐induced brain damage. It is speculated that astrogliosis and induction of iNOS protein expression in the neurons and astrocytes of the hippocampus may be in response to DA‐induced neuronal degeneration. Hippocampus 2003;13:375–387. © 2003 Wiley‐Liss, Inc.
Multiple hypothalamic sites control the frequency of hippocampal theta rhythm
Authors: Woodnorth Mary‐Anne , Kyd Rachel J. , Logan Barbara J. , Long Mark A. , McNaughton Neil
Published: March 2003

Stimulation of a neural pathway originating in the brainstem reticular formation, with synapses in the medial hypothalamus, activates the hippocampal theta rhythm. The frequency of reticular‐elicited theta is determined in the medial supramammillary nucleus (mSuM) completely in anaesthetised rats, but only partially when the animal is awake. We tested other medial hypothalamic sites for their capacity to control theta frequency in awake rats. Blockade of sodium channels (1 μl fast infusion of the local anaesthetic procaine, experiment 1) or increased inhibition by GABA (Chlordiazepoxide [CDP], experiment 2) was found to reduce or increase the frequency of reticular‐elicited theta, depending on the precise site of injection, in the region of the dorsomedial hypothalamic nucleus (DMH) and the posterior hypothalamic nucleus (PH). A band of null sites for CDP was located in the region of the ventral border of PH and dorsal border of mSuM. Using 0.5 and 1 μl CDP, and slow infusions (experiment 3), it was found that effective PH sites were also separate from mSuM in the rostrocaudal direction. In experiment 4, the DMH/PH region was mapped with unilateral and bilateral slow infusions of 0.5 μl CDP. CDP significantly reduced frequency in medial (periventricular) and dorsal PH, but not DMH. Bilateral injections appeared to generally sum the usual effects of unilateral injection, producing effects of intermediate size. However, the absolute frequency change in any given site, or with any pair of sites, did not exceed 1 Hz, which is similar to what is seen with single injections in mSuM. Overall, it appears that at, any one time, theta frequency may be determined by a complex interplay between distinct but interacting modulatory regions in the medial hypothalamus. Hippocampus 2003;13:361–374. © 2003 Wiley‐Liss, Inc.
Improving hydrogen/deuterium exchange mass spectrometry by reduction of the back‐exchange effect
Authors: Kipping Marc , Schierhorn Angelika
Published: March 2003

The measurement of deuterium incorporation kinetics using hydrogen/deuterium (H/D) exchange experiments is a valuable tool for the investigation of the conformational dynamics of biomolecules in solution. Experiments consist of two parts when using H/D exchange mass spectrometry to analyse the deuterium incorporation. After deuterium incorporation at high D2O concentration, it is necessary to decrease the D2O concentration before the mass analysis to avoid deuterium incorporation under artificial conditions of mass spectrometric preparation and measurement. A low D2O concentration, however, leads to back‐exchange of incorporated deuterons during mass analysis. This back‐exchange is one of the major problems in H/D exchange mass spectrometry and must be reduced as much as possible. In the past, techniques using electrospray ionization (ESI) had the lowest back‐exchange values possible in H/D exchange mass spectrometry. Methods for the measurement of H/D exchange by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) that have been developed since 1998 have some significant advantages, but they could not achieve the back‐exchange minima of ESI methods. Here, we present a protocol for H/D exchange MALDI‐MS which allows for greater minimization of back‐exchange compared with H/D exchange ESI‐MS under similar conditions. Copyright © 2003 John Wiley & Sons, Ltd.
Macromolecular assembly of Helicobacter pylori urease investigated by mass spectrometry
Authors: Pinkse Martijn W. H. , Maier Claudia S. , Kim Jung‐In , Oh Byung‐Ha , Heck Albert J. R.
Published: March 2003

The supramolecular assembly of Helicobacter pylori urease was studied by nanoflow electrospray ionization orthogonal time‐of‐flight mass spectrometry. The measured molecular mass of the urease complex of 1.06 MDa corresponds to a dodecameric (αβ)12 assembly of urease α (26 kDa) and β (61 kDa) subunits. The dodecamer disassembles readily into (αβ)3 subunits in solution and under controlled collisional‐induced dissociation in the gas phase. This is in strong support of an ((αβ)3)4 architecture consistent with the recently published x‐ray structure. In vitro, the α and β subunits are capable of re‐assembling to (αβ)3, but not further to the dodecameric complex. Copyright © 2003 John Wiley & Sons, Ltd.