bluuebunny/crossref_metadata_2025_split huggingface dataset:
Environmental degradation of biodegradable polyesters. IV. The effects of pores and surface hydrophilicity on the biodegradation of poly(ϵ‐caprolactone) and poly[(R)‐3‐hydroxybutyrate] films in controlled seawater
Authors: Tsuji Hideto , Suzuyoshi Kaori 
Published: August 2003

AbstractPoly(ϵ‐caprolactone) (PCL) and poly[(R)‐3‐hydroxybutyrate] (R‐PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as‐cast blend films (1:1) and by the alkali treatment of as‐cast nonporous films, respectively. These films, as well as as‐cast nonporous PCL and R‐PHB films, were biodegraded in static seawater kept at 25°C, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R‐PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 587–593, 2003
A comparison of youngsters' use of CD‐ROM and the Internet as information resources
Authors: Shenton Andrew K. , Dixon Pat 
Published: August 2003

AbstractLittle research has compared youngsters' use of CD‐ROM and the Internet for information‐seeking purposes. Nevertheless, the area has recently been addressed within a largely qualitative project more generally devoted to young people's information universes. Home access to the Internet was seen to be more limited than that to CD‐ROM, although the former was consulted to tackle needs of a greater number of types. The strategies employed to exploit each form of information resource were essentially similar. No attempts were reported to check the credibility of any information retrieved from electronic sources. The Internet was, however, used more frequently beyond the informants' own homes than was CD‐ROM. There was also greater employment of the Internet by adults acting on the youngsters' behalf. As Internet use for school purposes rose in accordance with age, that of CD‐ROM declined. When youngsters themselves compared the two resources as information‐seeking tools, CD‐ROM software was criticized for its lack of detailed material and the Internet for the problems in locating what was desired. Project findings have implications in a range of areas, including the marketing of CD‐ROM packages, research and development and practices within schools.
Relevance data for language models using maximum likelihood
Authors: Bodoff David , Wu Bin , Wong K. Y. Michael 
Published: August 2003

AbstractWe present a preliminary empirical test of a maximum likelihood approach to using relevance data for training information retrieval (IR) parameters. Similar to language models, our method uses explicitly hypothesized distributions for documents and queries, but we add to this an explicitly hypothesized distribution for relevance judgments. The method unifies document‐oriented and query‐oriented views. Performance is better than the Rocchio heuristic for document and/or query modification. The maximum likelihood methodology also motivates a heuristic estimate of the MLE optimization. The method can be used to test competing hypotheses regarding the processes of authors' term selection, searchers' term selection, and assessors' relevancy judgments.
An IP‐level analysis of usage statistics for electronic journals in chemistry: Making inferences about user behavior
Authors: Davis Philip M. , Solla Leah R. 
Published: August 2003

AbstractThis study reports an analysis of American Chemical Society electronic journal downloads at Cornell University by individual IP addresses. While the majority of users (IPs) limited themselves to a small number of both journals and article downloads, a small minority of heavy users had a large effect on total journal downloads. There was a very strong relationship between the number of article downloads and the number of users, implying that a user‐population can be estimated by just knowing the total use of a journal. Aggregate users (i.e. Library Proxy Server and public library computers) can be regarded as a sub‐sample of the entire user population. Analysis of article downloads by format (PDF versus HTML) suggests that individuals are using the system like a networked photocopier, for the purposes of creating print‐on‐demand copies of articles.
Peripheral social awareness information in collaborative work
Authors: Spring Michael B. , Vathanophas Vichita 
Published: August 2003

AbstractPeople working in physical proximity have access to information about one another. Much of this information is unavailable when people collaborate remotely using groupware. Being aware of other members of a team in a collaborative environment involves knowing both what people are doing and what is happening to the shared information space or artifact. Increasing the amount of information about the group in a computer‐mediated system may increase the group's ability to complete the task. This article reports on a study that examined group performance on a task that was computer mediated with and without awareness information. In particular, the study examined how an awareness tool impacts the quality of the work effort and the communications between group members in the completion of a collaborative authoring task. The study found that the use of an awareness tool decreased the quality of the work effort. The number of communications also decreased when the tool was used. Although the results contradict some of the theoretical predictions, an examination of the data suggests theoretical support for a more complex interaction. There was evidence that the awareness tool may have reduced the users' need to communicate and this reduction in communications may have caused the reduction in the quality of the work effort. There is also data to suggest that the existence of the awareness tool may have negatively influenced the effort of some participants, and it was that effort reduction that caused the reduction in the quality of the product.
Greeklish: An experimental interface for automatic transliteration
Authors: Karakos Alexandros 
Published: August 2003

Abstract“Transliteration” in linguistics means the system of conveying as nearly as possible by means of one set of letters or characters the pronunciation of the words in languages written and printed in a totally different script. This term may be applied to a transcription in Latin letters of Greek, Hebrew, or the Slavonic languages written in the Cyrillic alphabet. We present in this article Greeklish, a Windows application that automatically produces English to Greek transliteration and back‐transliteration (retransliteration). This transliteration is based on an algorithm with a table of associations between the two character sets. This table can be modified by the user so that it can cover personal preferences or formal present and future rules. The novelty of this system is its speed of operation, its simplicity, and its ease of use. Our examples use a Greek to Latin (English) alphabet mapping, but the Greeklish application can easily use any X to Latin mapping, where X is any non‐Latin alphabet.
Clays as a Host Matrix in the Synthesis of Organic Macrocycles
Authors: Georgakilas Vasilios , Gournis Dimitrios , Bourlinos Athanasios B. , Karakassides Michael A. , Petridis Dimitrios 
Published: August 2003

AbstractA new approach for the synthesis of amide macrocycles, based on the use of organo‐clay derivatives as controlling template, is proposed as an alternative to the rotaxane method. Dications of p‐xylylene diamine inserted in the clay interlayer space act as molding pillars around which neutral diamine molecules are erected via hydrogen bonding and π–π interactions to form supramolecular arrays. Condensation of diamines in the supramolecular arrays with diacetyl dichlorides yields various tetramide macrocycles in good yields. Shape, aromaticity and dimensions of the reactants are factors affecting the condensation reaction.
Study on the Phase Behaviors, Viscosities, and Thermodynamic Properties of CO2/[C4mim][PF6]/Methanol System at Elevated Pressures
Authors: Liu Zhimin , Wu Weize , Han Buxing , Dong Zexuan , Zhao Guoying , Wang Jiaqiu , Jiang Tao , Yang Guanying 
Published: August 2003

AbstractAn apparatus to determine the vapor–liquid equilibria of CO2/ionic liquid (IL)/organic solvent multisystems and the viscosity of the liquid phase at elevated pressures has been constructed. The solubility of CO2 in 3‐butyl‐1‐methyl‐imidazolium hexafluorophosphate ([C4mim][PF6]) and the viscosity of CO2‐saturated [C4mim][PF6] have been studied at 313.15, 323.15, and 333.15 K and at pressures up to 12.5 MPa. The phase behavior of CO2/[C4mim][PF6]/methanol ternary mixture and the viscosity of the liquid phases at equilibrium condition have also been determined at 313.15 K and at 7.15 and 10.00 MPa. The partition coefficients of the components in the ternary system are calculated. Peng–Robinson equation of state and some thermodynamic functions are combined to calculate the fugacity coefficients of the components in the system. It demonstrates that the viscosity of the IL‐rich phase decreases significantly with increasing pressure of CO2, and the effect of temperature on the viscosity of CO2/IL mixture is not noticeable at high pressure, although the viscosity of the CO2‐free IL decreases dramatically with increasing temperature. Compressed CO2 may become an attractive reagent for reducing the viscosity of ILs in many applications. The mole fraction of methanol in the CO2‐rich phase is much lower than that in the IL‐rich phase; this indicates that the interaction between the IL and methanol is stronger than that between CO2 and methanol. The fugacity coefficient of CO2 in IL‐rich phase is larger than unity, while that of methanol is much small than unity, which further suggests that methanol–IL interaction is much stronger than CO2–IL interaction. However, the CO2–IL interaction is stronger than the CO2–methanol interaction.
Electrostatic Complexation and Photoinduced Electron Transfer between Zn‐Cytochrome c and Polyanionic Fullerene Dendrimers
Authors: Braun Martin , Atalick Stefan , Guldi Dirk M. , Lanig Harald , Brettreich Michael , Burghardt Stephan , Hatzimarinaki Maria , Ravanelli Elena , Prato Maurizio , van Eldik Rudi , Hirsch Andreas 
Published: August 2003

AbstractTwo dendritic fullerene (DF) monoadducts, 2 and 3, which can carry up to 9 and 18 negative charges, respectively, were examined with respect to electrostatic complexation with Cytochrome c (Cytc). To facilitate comprehensive photophysical investigations, the zinc analogue of Cytc (ZnCytc) was prepared according to a novel, modified procedure. The association of ZnCytc and DF, and consequential photoinduced electron transfer within ZnCytc‐DF from the photoexcited protein to the fullerene, was proven by fluorescence spectroscopy and transient absorption spectroscopy. These findings were also supported by circular dichroism as well as by extensive molecular dynamics (MD) simulations.
A Simplified and Convenient Laboratory‐Scale Preparation of 14N or 15N High Molecular Weight Poly(dichlorophosphazene) Directly from PCl5
Authors: Carriedo Gabino A. , García Alonso Francisco. J. , Gómez‐Elipe Paloma , Fidalgo J. Ignacio , García Álvarez J. L. , Presa‐Soto A. 
Published: August 2003

AbstractA simple and convenient one‐pot synthesis of THF solutions of high molecular weight poly(dichlorophosphazene) [NPCl2]n, or the 15N isotopomer [15NPCl2]n, starting directly from PCl5 and NH4Cl or 15NH4Cl in a solution of 1,2,4‐trichlorobenzene in the presence of sulfamic acid and calcium sulfate dihydrate, is described. The solutions of [NPCl2]n in THF, which are obtained free of poly(tetrahydrofuran) by preparing them in the presence of K2CO3, can be reacted directly with phenols, biphenols, or even HO‐CH2CF3 in the presence of K2CO3 or Cs2CO3 to obtain, after a very simple workup, the corresponding polyphosphazene derivatives almost free of chlorine.
Syntheses, Structures, Photoluminescence, and Theoretical Studies of a Novel Class of d10 Metal Complexes of 1H‐[1,10]phenanthrolin‐2‐one
Authors: Zheng Shao‐Liang , Zhang Jie‐Peng , Chen Xiao‐Ming , Huang Zhen‐Li , Lin Zhen‐Yang , Wong Wing‐Tak 
Published: August 2003

AbstractA novel asymmetric monosubstituted 1,10‐phenanthroline, Hophen⋅0.5 H2O (1, Hophen=1H‐[1,10]phenanthrolin‐2‐one), was generated by a facile route, and a novel class of crystalline, d10‐metal, monomeric or oligomeric complexes of this ligand, namely [Hg(ophen)2]⋅4 H2O⋅CH2Cl2 (2), [Cd3Cl(ophen)5]⋅1.5 H2O⋅2 CH2Cl2 (3), and [Zn4O(ophen)4(OAc)2]⋅4H2O⋅2 CH2Cl2 (4), were obtained by means of liquid diffusion, and were characterized by X‐ray crystallography and photoluminescence studies. Complex 1 exhibits a hydrogen‐bonded dimeric structure, 2 is a neutral monomeric complex, 3 has a trinuclear structure with the ophen ligand acting as a bridge through the ketone groups, and 4 features a tetranuclear Zn4O core that is consolidated further by bridging ophen and acetate ligands. All the complexes display photoluminescent properties in the blue/green region. The photoluminescent mechanisms were investigated by means of molecular orbital calculations, which showed that the photoluminescent properties are ligand‐based and can be tuned upon ligation to different metal ions.
Spectroelectrochemical Studies on Mixed‐Valence States in a Cyanide‐Bridged Molecular Square, [RuII2FeII2(μ‐CN)4(bpy)8](PF6)4⋅CHCl3⋅H2O
Authors: Oshio Hiroki , Onodera Hironori , Ito Tasuku 
Published: August 2003

AbstractA cyanide‐bridged molecular square of [RuII2FeII2(μ‐CN)4(bpy)8](PF6)4⋅CHCl3⋅H2O, abbreviated as [RuII2FeII2](PF6)4, has been synthesised and electrochemically generated mixed‐valence states have been studied by spectroelectrochemical methods. The complex cation of [RuII2FeII2]4+ is nearly a square and is composed of alternate RuII and FeII ions bridged by four cyanide ions. The cyclic voltammogram (CV) of [RuII2FeII2](PF6)4 in acetonitrile showed four quasireversible waves at 0.69, 0.94, 1.42 and 1.70 V (vs. SSCE), which correspond to the four one‐electron redox processes of [RuII2FeII2]4+ ⇄[RuII2FeIIFeIII] 5+⇄[RuII2FeIII2]6+⇄[RuIIRuIIIFeIII2]7+⇄[RuIII2FeIII2]8+. Electrochemically generated [RuII2FeIIFeIII]5+ and [RuII2FeIII2]6+ showed new absorption bands at 2350 nm (ε=5500 M−1 cm−1) and 1560 nm (ε=10 500 M−1 cm−1), respectively, which were assigned to the intramolecular IT (intervalence transfer) bands from FeII to FeIII and from RuII to FeIII ions, respectively. The electronic interaction matrix elements (HAB) and the degrees of electronic delocalisation (α2) were estimated to be 1090 cm−1 and 0.065 for the [RuII2FeIIFeIII2]5+ state and 1990 cm−1 and 0.065 for the [RuII2FeIII2]6+ states.
A Practical High‐Throughput Screening System for Enantioselectivity by Using FTIR Spectroscopy
Authors: Tielmann Patrick , Boese Matthias , Luft Martin , Reetz Manfred T. 
Published: August 2003

Abstract For the first time FTIR spectroscopy has been applied to the measurement of enantiomeric purity. The underlying concept is based on the use of pseudo‐enantiomers that are 13C‐labeled at appropriate positions. Upon applying Lambert–Beer's law in the determination of the concentrations of both enantiomers, the ee values are accessible, accuracy to within ±5 % of the true values being possible. The application of a commercially available high‐throughput FTIR system results in a slightly decreased accuracy (±7 % for the ee values), but this allows a throughput of up to 10 000 samples per day. The method is of interest in the area of combinatorial asymmetric catalysis and directed evolution of enantioselective enzymes.
Cation Sensors Based on Terpyridine‐Functionalized Boradiazaindacene
Authors: Goze Christine , Ulrich Gilles , Charbonnière Loïc , Cesario Michèle , Prangé Thierry , Ziessel Raymond 
Published: August 2003

AbstractA new class of highly luminescent dyes is reported. The characteristic feature of these compounds is that a terpyridine fragment is closely appended to a boradiazaindacene moiety in such a way that cation binding to the vacant terpyridine causes strong perturbations of the photophysical properties of the boradiazaindacene unit. In particular, these sensors are especially applicable to the fluorescence detection of trace quantities of zinc(II) ions in solution. The mechanism of the cation‐induced quenching process has been investigated by a combination of electrochemistry, UV/Vis absorption, emission, and NMR spectroscopy. Highly luminescent arrays can be formed by doping transparent polymers with low concentrations of these new dyes. In such materials, the change in photophysical properties upon cation binding is so marked that “cation writing” becomes feasible under routine conditions.
Temperature‐Dependent Behavior of Protein‐Chromophore Interactions: A Theoretical Study of a Blue Fluorescent Antibody
Authors: Salsbury Freddie R. , Han Wen‐Ge , Noodleman Louis , Brooks Charles L. 
Published: August 2003

AbstractThe unusual temperature‐dependent excited‐state dynamics of a stilbene–antibody complex reported by Simeonov et al. are explored using theoretical methods. The anomalous temperature‐dependent fluorescence emission and lifetime are shown to be the result of interplay among temperature‐modulated protein flexibility, the excited‐state potential surface for the stilbene central twist, and changes in the stilbene charge distribution upon excitation. Stilbene is found to possess a similar geometry and orientation within the antibody binding pocket at all temperatures in the ground state and at low temperatures (≈240 K) in the excited state. At higher temperatures (≈260 K), the excited‐state conformation twists around the central double bond and adopts an alternate orientation within the binding pocket. These changes result from protein side chain and loop motions that are frozen out at lower temperatures and account for the observed red shift of the fluorescence emission spectrum (a calculated shift of 3.8 kcal mol−1 compares favorably with the ≈5 kcal. mol−1 observed experimentally). Approximately 3.0 kcal mol−1 of this stabilization is global in nature and is not attributable to specific local interactions. Local interactions between stilbene and Tyr‐B39 contribute ≈0.8 kcal mol−1 to the fluorescence shift. The primary structural change in simulations of the high temperature excited state involves a decrease in the stilbene–tyrosine distance and a relative change in orientation of the aromatic rings. We identify several nearby charged residues that contribute to the fluorescence emission shift and provide targets for mutagenesis to probe the temperature‐dependent dynamics of protein–chromophore interactions.
Evaluation of one‐ and two‐equation low‐Re turbulence models. Part II—Vortex‐generator jet and diffusing S‐duct flows
Authors: Yaras M. I. , Grosvenor A. D. 
Published: August 2003

AbstractThis second segment of the two‐part paper systematically examines several turbulence models in the context of two flows, namely a vortex flow created by an inclined jet in crossflow, and the flow field in a diffusing S‐shaped duct. The test cases are chosen on the basis of availability of high‐quality and detailed experimental data. The tested turbulence models are integrated to solid surfaces and consist of: Rodi's two‐layer k–ε model, Wilcox's k–ω model, Menter's two‐equation shear–stress‐transport model, and the one‐equation model of Spalart and Allmaras. The objective of the study is to establish the prediction accuracy of these turbulence models with respect to three‐dimensional separated flows with streamline curvature. At the same time, the study establishes the minimum spatial resolution requirements for each of these turbulence closures, and identifies the proper low‐Mach‐number preconditioning and artificial diffusion settings of a Reynolds‐averaged Navier–Stokes algorithm for optimum rate of convergence and minimum adverse impact on prediction accuracy. Copyright © 2003 John Wiley & Sons, Ltd.
Isolation of volatile oil from thyme (Thymbra spicata) by steam distillation
Authors: Hancı Serap (Sonsuzer) , Sahin Serpil , Yılmaz Levent 
Published: August 2003

AbstractThe effects of steam flow rate (1.03 and 0.64 L/h( distillation time, and particle size (0.50, 1.00, 2.05 mm) of Thymbra spicata on essential oil yield and sequence of extraction of compounds were studied. A logarithmic model fitted well to experimental data. The composition of the essential oil obtained by steam distillation was investigated for whole leaves only since the grinding had an adverse effect on yield. The oil obtained was very rich with respect to its carvacrol content. For both steam flow rates, oxygenated monoterpenes were recovered the most rapidly. Using whole leaves (2.05 mm) and a higher steam flow rate (1.03 L/h) for 75 min of distillation was chosen as the optimum which gives the lowest amount of monoterpene hydrocarbons, the complete recovery of oxygenated compounds, and the highest yield in a shorter time. Yield was 1.57% at this optimum condition. The oil was composed of 53.1% oxygenated compounds, 25.7% monoterpene hydrocarbons, 4.4% sesquiterpenes, and 14.1% p‐cymene.
Assessment of protein nutritional quality and effects of traditional processes: A comparison between Ethiopian quality protein maize and five Ethiopian adapted normal maize cultivars
Authors: Fufa Habtamu , Akalu Girma , Wondimu Asrat , Taffesse Samson , Gebre Takele , Schlosser Karla , Noetzold Horst , Henle Thomas 
Published: August 2003

AbstractThe present study was designed to quantitatively measure and compare the levels and variations of total protein, individual amino acids, and computed protein efficiency ratio (C‐PER) in raw and traditionally processed products of one recently released quality protein maize (QPM BH542) with four high‐yield maize hybrids, namely flint BH660, semi‐dent BH140, Pioneer 30H83, and Pioneer 30G97, as well as one local maize cultivar. The total protein content was variable among the cultivars ranging from 7% for BH660 to 8.6% for Pioneer 30H83, 8.9% for BH140, 9.8% for QPM BH542, 10.1% for local maize cultivar, and 11.8% for Pioneer 30G97, respectively. However, the QPM BH542 maize protein proved to be higher in nutritional quality than common maize proteins because it contained 30% to 82% more lysine, higher levels of arginine, tryptophan, histidine, threonine, cysteine, and valine. As a result, the QPM BH542 amino acid profile gives a good balance of total essential amino acids, limited only in lysine, and has a C‐PER ratio of 2.2 compared to 1.14, 1.2, 1.4, 1.66, and 1.67 for Pioneer 30G97, local, BH‐140, BH660, and Pioneer 30H83, respectively. The various traditional processes of maize have no significant effect on the protein nutritional quality of the new quality protein maize. Hence, the widely dissemination of it in agricultural cultivation as well as consumption by the general population is recommended.