bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental study of fuel decomposition and hydrocarbon growth processes for practical fuel components in nonpremixed flames: MTBE and related alkyl ethers
Authors: McEnally Charles S. , Pfefferle Lisa D. 
Published: April 2004

AbstractFuel decomposition and hydrocarbon growth processes of methyl tert‐butyl ether (MTBE) and related alkyl ethers have been studied experimentally in soot‐producing nonpremixed flames. Temperature, C1–C12 hydrocarbons, and major species were measured in coflowing methane/air flames whose fuel was separately doped with 5000 ppm of MTBE, n‐butyl methyl ether (NBME), sec‐butyl methyl ether (SBME), ethyl tert‐butyl ether (ETBE), and tert‐amyl methyl ether (TAME; =1,1‐dimethylpropyl methyl ether). The consumption rates of the dopants, several simple kinetic calculations, and the dependence of the observed products on fuel composition indicate that the dominant decomposition process was unimolecular dissociation, not H‐atom abstraction. The dominant dissociations were four‐center elimination of alcohols for the doubly branched ethers (MTBE, ETBE, and TAME) and CO fission for the linear ether (NBME), while four‐center elimination and CO fission were comparably important for the singly branched ether (SBME). These dissociations produced alkenes which further reacted to produce alkadienes/alkynes, alkenynes, acetylenic compounds, and aromatics. The dependence of the maximum benzene mole fractions on fuel composition was consistent with benzene formation through reactions of highly‐unsaturated C3 and/or C4 hydrocarbons (C3H3, n‐C4H3, C4H4, n‐C4H5, etc.). © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 345–358, 2004
Peptide/Protein Hybrid Materials: Enhanced Control of Structure and Improved Performance through Conjugation of Biological and Synthetic Polymers
Authors: Vandermeulen Guido W. M. , Klok Harm‐Anton 
Published: April 2004

AbstractSummary: The conjugation of peptides/proteins and synthetic polymers is a useful strategy to overcome some of the limitations related to the use of the individual components. This review will highlight two aspects: enhanced structural control at the nanometer level and improved performance, in particular with respect to biomedical applications. In the former case, peptide sequences are mainly used to mediate self‐assembly of synthetic polymers. In the latter case, conjugation of an appropriate synthetic polymer to a pharmaceutically active peptide/protein can, for example, prevent premature enzymatic degradation and enhance blood circulation times, which is therapeutically advantageous.image
Monitoring of the Gelation Process on a Radical Chain Cross‐Linking Reaction Based onN‐Vinylcaprolactam by Using Dynamic Light Scattering
Authors: Boyko Volodymyr , Richter Sven 
Published: April 2004

AbstractSummary:The sol‐gel transition of radical chain cross‐linking copolymerization system [N‐vinylcaprolactam (monomer)/3,3′‐(ethane‐1,1‐diyl)bis(1‐vinyl‐2‐pyrrolidone) (cross‐linker)] has been studied using in situ by time‐resolved dynamic light scattering (DLS). A critical dynamical behavior was observed near the sol‐gel transition, which is characterized by the presence of power‐law spectra over three decades in the time‐intensity correlation functiong2(t) − 1 ∼ t−μ. It was found, that the critical exponentμis dependent on the amount of the cross‐linker: higher the amount of the cross‐linker, higher is the value of the exponentμ. The occurrence of speckle patterns in the scattered intensity profile and of a power law behavior in the time‐intensity correlation function appeared at the same time. At the lowest concentration of 0.25% cross‐linker, no power law was observed. The estimated values forμwere in the range of 0.39 ≤ μ ≤ 0.577. It can be concluded, that the amount of branching in the critical gel determines the value ofμ.magnified image
Photoreversible Chain Extension of Poly(ethylene glycol)
Authors: Trenor Scott R. , Long Timothy E. , Love Brian J. 
Published: April 2004

AbstractSummary: Coumarin containing poly(ethylene glycol) monols and diols were prepared in a telechelic fashion using quantitative end group esterification. The coumarin modified poly(ethylene glycol) monols and diols were solution cast into films (1 to 15 μm) and chain extended via the dimerization of the coumarin derivatives with UVA (>300 nm) light irradiation. The coumarin‐modified PEG diol doubled in molecular weight, and the molecular weight distribution increased from 1.17 to 2.75 upon exposure to 110 J · cm−2 of UVA light. The chain extended poly(ethylene glycol)s were subsequently converted to their original molecular weight via the photocleavage reaction of the coumarin dimer at 254 nm with less than 2 J · cm−2. The photoreversible chain length modulation was monitored utilizing GPC, DSC and UV‐Vis spectroscopy.Molecular weight modulation of COU‐PEG‐COU.magnified imageMolecular weight modulation of COU‐PEG‐COU.
Evidence of Intramolecular Cyclization in Copolymerization of Ethylene with 1,3‐Butadiene: Thermal Properties of the Resulting Copolymers
Authors: Monteil Vincent , Spitz Roger , Barbotin Fanny , Boisson Christophe 
Published: April 2004

AbstractSummary: Ethylene and butadiene were copolymerized with a silylene‐bridged bis(fluorenyl) complex {[Me2Si(C13H8)2]NdCl} (1) in combination with various alkylating agents (BuLi/AlH(iBu)2, (Bu)MgCl, Mg(Bu)(Oct)). Copolymers have a unique microstructure since they contain 1,2‐cyclohexane rings and unsaturations along the polymer chain. An intramolecular mechanism was proposed for the formation of six‐membered rings. The influence of these cyclic structures on thermal properties of the copolymers has been investigated.Proposed mechanism for formation of 1,2‐cyclohexane rings.magnified imageProposed mechanism for formation of 1,2‐cyclohexane rings.
Lattice embeddings and array noncomputable degrees
Authors: Walk Stephen M. 
Published: April 2004

AbstractWe focus on a particular class of computably enumerable (c. e.) degrees, the array noncomputable degrees defined by Downey, Jockusch, and Stob, to answer questions related to lattice embeddings and definability in the partial ordering (ℜ︁, ≤) of c. e. degrees under Turing reducibility. We demonstrate that the latticeM5 cannot be embedded into the c. e. degrees below every array noncomputable degree, or even below every nonlow array noncomputable degree. As Downey and Shore have proved that M5 can be embedded below every nonlow2 degree, our result is the best possible in terms of array noncomputable degrees and jump classes. Further, this result shows that the array noncomputable degrees are definably different from the nonlow2 degrees. We note also that there are embeddings of M5 in which all five degrees are array noncomputable, and in which the bottom degree is the computable degree 0 but the other four are array noncomputable. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Boolean algebras of definable sets in weakly o‐minimal theories
Authors: Leonesi Stefano , Toffalori Carlo 
Published: April 2004

AbstractWe consider the sets definable in the countable models of a weakly o‐minimal theory T of totally ordered structures. We investigate under which conditions their Boolean algebras are isomorphic (hence T is p‐ω‐categorical), in other words when each of these definable sets admits, if infinite, an infinite coinfinite definable subset. We show that this is true if and only if T has no infinite definable discrete (convex) subset. We examine the same problem among arbitrary theories of mere linear orders. Finally we prove that, within expansions of Boolean lattices, every weakly o‐minimal theory is p‐ω‐categorical. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An infinitary variant of Metric Temporal Logic over dense time domains
Authors: Baratella Stefano , Masini Andrea 
Published: April 2004

AbstractWe introduce a complete and cut‐free proof system for a sufficiently expressive fragment of Metric Temporal Logic over dense time domains in which a schema of induction is provable. So doing we extend results previously obtained by Montagna et al. to unbounded temporal operators. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A general approach to fuzzy concepts
Authors: Popescu Andrei 
Published: April 2004

AbstractThe paper proposes a flexible way to build concepts within fuzzy logic and set theory. The framework is general enough to capture some important particular cases, with their own independent interpretations, like “antitone” or “isotone” concepts constructed from fuzzy binary relations, but also to allow the two universes (of objects and attributes) to be equipped each with its own truth structure. Perhaps the most important feature of our approach is that we do not commit ourselves to any kind of logical connector, covering thus the case of a possibly non‐commutative conjunction too. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constructive complements of unions of two closed sets
Authors: Bridges Douglas S. 
Published: April 2004

AbstractIt is well known that in Bishop‐style constructive mathematics, the closure of the union of two subsets of ℝ is ‘not’ the union of their closures. The dual situation, involving the complement of the closure of the union, is investigated constructively, using completeness of the ambient space in order to avoid any application of Markov's Principle. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fragments of Martin's Maximum in generic extensions
Authors: König Bernhard , Yoshinobu Yasuo 
Published: April 2004

AbstractWe show that large fragments of MM, e. g. the tree property and stationary reflection, are preserved by strongly (ω1 + 1)‐game‐closed forcings. PFA can be destroyed by a strongly (ω1 + 1)‐game‐closed forcing but not by an ω2‐closed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of Processing Additives on Adhesive Properties of Surface‐Modified Low‐Density Polyethylene
Authors: Novák Igor , Florián Štěpán 
Published: April 2004

AbstractSummary: The paper deals with the surface and adhesive properties of low‐density polyethylene modified by corona discharge, which appear during the long‐term hydrophobic recovery of the modified polymer. The study was aimed at the change in polarity during aging of low‐density polyethylene modified by corona discharge reducing the surface free energy, its polar component and the mechanical work of adhesion. During the long‐term hydrophobization of low‐density polyethylene the main decrease of the surface properties appeared within the first 30 d after modification. In the course of further aging the hydrophobic recovery of the polymer proceeded more slowly. It has been found that the value of the surface and adhesive properties of low‐density polyethylene after modification with corona discharge as well as the dynamics of their decrease during the aging is to a great extent dependent on the presence of the processing additives in the polymer.Mechanical work of adhesion of LDPE modified by corona discharge to poly(vinyl acetate) during hydrophobic recovery: a) additive‐free LDPE, b) LDPE with additives.imageMechanical work of adhesion of LDPE modified by corona discharge to poly(vinyl acetate) during hydrophobic recovery: a) additive‐free LDPE, b) LDPE with additives.
The Relationship between Microstructure and Properties in PP/Rubber Powder/nano‐CaCO3 Ternary Blends
Authors: Su Xinqing , Hua Youqing , Qiao Jinliang , Liu Yiqun , Zhang Xiaohong , Gao Jianming , Song Zhihai , Huang Fan , Zhang Manli 
Published: April 2004

AbstractSummary: A new kind of rubber powder with “salami” structure (RPS) was prepared by spray drying the mixture of styrene‐butadiene rubber latex and nano‐CaCO3 slurry. It was found that RPS is an effective toughener with synergistic toughening effect on poly(propylene) (PP). The Izod impact strength of PP/RPS blend is not only higher than that of PP/rubber powder or PP/nano‐CaCO3 blends, but also higher than that of a PP/rubber powder/CaCO3 blend. TEM images show that the microstructure of the PP/RPS blend is an “island‐sea” structure with “salami” structure in RPS, in which nano‐CaCO3 particles are embedded in styrene‐butadiene rubber particles. The relationship between properties and microstructure has been studied by using TEM, SEM, DSC, etc.image
Nitroxide‐Controlled Grafting by an Insertion Mechanism using a Polymerizable N‐Oxyl
Authors: Appelt Mathias , Schmidt‐Naake Gudrun 
Published: April 2004

AbstractSummary: The polymerizable nitroxide 4‐acryloyloxy‐2,2,6,6‐tetramethylpiperidine‐N‐oxyl (AOTEMPO) was utilized in a two step polymerization to prepare alkoxyamine‐functionalized backbone polymers. These backbones were then used as initiators for stable free‐radical graft polymerizations in bulk at 125 °C. The products were cleaved into their linear components by reaction with L‐(+)‐ascorbic acid allowing a reproducible analysis of the molecular weights. The influences of the backbone concentration and the graft density on the polymerization were investigated. Graft polymers purely consisting of styrene were produced as well as polymers with a backbone based on 2‐ethoxyethyl acrylate (EOEA). In addition a graft polymer with block copolymer side chains was prepared by extending a preformed graft polymer. In all cases the controlled course of the reaction was confirmed by the linear increase of the molecular weights over conversion and the low polydispersities of the products.Structure of an extended graft copolymer.imageStructure of an extended graft copolymer.
Hydrogenation of Styrene‐Butadiene Rubber Catalyzed by Ru(CHCHPh)Cl(CO)(PCy3)2
Authors: Pan Qinmin , Rempel Garry L. 
Published: April 2004

AbstractSummary: The hydrogenation of a copolymer of styrene and butadiene (SBR) catalyzed by Ru(CHCHPh)Cl(CO)(PCy3)2 was experimentally investigated within the temperature range of 120–160 °C, at P of 300–1 200 psi, and a catalyst concentration of 10–78 × 10−6 M. Special attention was paid to minimizing the catalyst metal residue and crosslinking in the product. The results indicated that high‐quality hydrogenated SBR was achieved without crosslinking and the metal residue was less than 7 ppm without a post‐treatment.IR spectra of the styrene–butadiene rubber before (a) and after (b) hydrogenation with the Ru(CHCHPh)Cl(CO)(PCy3)2 catalyst were observed as reported here. The disappearance of all characteristic absorbencies of CC (724, 910, 967, and 994 cm−1) suggests nearly quantitative hydrogenation of the CC bonds.imageIR spectra of the styrene–butadiene rubber before (a) and after (b) hydrogenation with the Ru(CHCHPh)Cl(CO)(PCy3)2 catalyst were observed as reported here. The disappearance of all characteristic absorbencies of CC (724, 910, 967, and 994 cm−1) suggests nearly quantitative hydrogenation of the CC bonds.
Negative Electrorheological Effect of Silicone Gels Containing Barium Titanate
Authors: Mitsumata Tetsu , Sugitani Kousuke 
Published: April 2004

AbstractSummary: We observed the negative electrorheological phenomenon on swollen silicone gels containing barium titanate. Contrary, no negative electrorheological effect was observed in unswollen silicone gels containing barium titanate and silicon gels without barium titanate. The change in storage modulus increased with increasing DC electric field strength. The effects of frequency, degree of swelling, and the field strength have been investigated.Electric‐field dependence of the change in storage modulus at f = 0.1 Hz for swollen silicone/BaTiO3 gels with varying CAT content; (○): CAT 0.1, (□): CAT 0.2, (⋄): CAT 0.3, (×): SG.imageElectric‐field dependence of the change in storage modulus at f = 0.1 Hz for swollen silicone/BaTiO3 gels with varying CAT content; (○): CAT 0.1, (□): CAT 0.2, (⋄): CAT 0.3, (×): SG.
Synthesis and Characterization of a Novel, Mesoporous Organosilica with Additional Cyclodextrin‐Based Micropores
Authors: Liu Chunqing , Wang Jinfeng , Economy James 
Published: April 2004

AbstractSummary: A novel mesoporous organosilica with additional cyclodextrin‐based micropores has been synthesized from tetraethoxysilane (TEOS) and cyclodextrin‐based silane monomer precursors and triblock PEO‐PPO‐PEO (poly(ethylene oxide)‐poly(propylene oxide)‐ poly(ethylene oxide)) copolymer P123 as the structure‐directing template with the aid of sodium chloride and the supramolecular assembly of cyclodextrins with P123.The synthesis of CD‐Si‐2%.imageThe synthesis of CD‐Si‐2%.
Synthesis and Cyclohexene Oxide/Carbon Dioxide Copolymerizations of Zinc Acetate Complexes Bearing Bidentate Pyridine‐Alkoxide Ligands
Authors: Kim Il , Kim Sang Mook , Ha Chang‐Sik , Park Dae‐Won 
Published: April 2004

AbstractSummary: The reaction of 2‐lithio‐6‐methylpyridine or 2‐lithiopyridine and the appropriate diaryl ketone followed by hydrolysis yields 6‐Me‐pyCAr2OH pyridine alcohols or pyCAr2OH pyridine alcohols. The reactions of zinc acetate with 1 equiv. of the lithiated products of the ligands proceed rapidly to afford LiOAc salt and mono‐ligand complexes (6‐Me‐pyCAr2O)Zn(OAc) and (pyCAr2O)Zn(OAc), respectively, in high yield. The copolymerizations of carbon dioxide with cyclohexene oxide were investigated. The (6‐Me‐pyCAr2O)Zn(OAc) showed moderate yield and CO2 incorporation. The [6‐Me‐pyC(4‐Cl‐C6H4)2O]Zn(OAc) complex gave large polymers with high proportions of carbonate linkage (>60%) and narrow polydispersity, indicating single active sites.The monoligated Zn complexes synthesized and used here as catalysts for the copolymerization of cyclohexene oxide and carbon dioxide.imageThe monoligated Zn complexes synthesized and used here as catalysts for the copolymerization of cyclohexene oxide and carbon dioxide.
Diffusion‐Controlled Particle Growth and its Effects on Nucleation in Stirred Emulsion Polymerisation Reactors
Authors: Sajjadi Shahriar 
Published: April 2004

AbstractSummary: Particle formation and growth in the batch emulsion homo‐polymerisation of styrene and methyl methacrylate monomers under diffusion‐controlled conditions were studied. The polymerisations started with two stratified layers of a monomer and water containing an initiator and a surfactant, with the water layer being gently stirred. Because of limitations in monomer transport, the rate of particle growth was substantially reduced and as a result a large number of polymer particles formed.Schematic presentation of the highly diffusion‐controlled polymerisation.imageSchematic presentation of the highly diffusion‐controlled polymerisation.
Polymer‐Bound, Amphiphilic Hoveyda‐Grubbs‐Type Catalyst for Ring‐Closing Metathesis in Water
Authors: Zarka M. Tobias , Nuyken Oskar , Weberskirch Ralf 
Published: April 2004

AbstractSummary: We report on the synthesis of a new amphiphilic, polymer‐bound variant of the Hoveyda‐Grubbs catalyst via the coupling reaction of a carboxylic acid‐functionalized poly(2‐oxazoline) block copolymer with 2‐isopropoxy‐5‐hydroxystyrene and subsequent reaction of the resulting macroligand with a second generation Grubbs catalyst. For the benchmark, the substrate diethyl diallylmalonate was studied in the ring‐closing metathesis (RCM) reaction and a turn‐over number (TON) of up to 390 in water was achieved. To the best of our knowledge, this is the highest value for any aqueous RCM reaction to date. For the first time, recycling of a ruthenium initiator in an aqueous RCM reaction has been successful to some extent. In addition, the micellar conditions accelerate the conversion of the hydrophobic diene and at the same time stabilize the active alkylidene species, although competing decomposition of the catalyst in water still impairs the catalyst performance. Residual ruthenium content was determined to be below 1 ppm in the product suggesting a very low leaching of the polymeric catalyst system.Simplified chemical structure of the amphiphilic, polymer‐bound Grubbs‐Hoveyda catalyst.imageSimplified chemical structure of the amphiphilic, polymer‐bound Grubbs‐Hoveyda catalyst.
Selective human enterovirus and rhinovirus inhibitors: An overview of capsid‐binding and protease‐inhibiting molecules
Authors: Shih Shin‐Ru , Chen Shu‐Jen , Hakimelahi Gholam Hossein , Liu Hsing‐Jang , Tseng Chen‐Tso , Shia Kak‐Shan 
Published: April 2004

AbstractThe absence of effective vaccines for most viral infections highlights an urgent necessity for the design and development of effective antiviral drugs. Due to the advancement in virology since the late 1980s, several key events in the viral life cycle have been well delineated and a number of molecular targets have been validated, culminating in the emergence of many new antiviral drugs in recent years. Inhibitors against enteroviruses and rhinoviruses, responsible for about half of the human common colds, are currently under active investigation. Agents targeted at either viral protein 1 (VP1), a relatively conserved capsid structure mediating viral adsorption/uncoating process, or 3C protease, which is highly conserved among different serotypes and essential for viral replication, are of great potential to become antipicornavirus drugs. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 4, 449–474, 2004
DNA minor groove binders as potential antitumor and antimicrobial agents
Authors: Baraldi Pier Giovanni , Bovero Andrea , Fruttarolo Francesca , Preti Delia , Tabrizi Mojgan Aghazadeh , Pavani Maria Giovanna , Romagnoli Romeo 
Published: April 2004

AbstractDNA minor groove binders constitute an important class of derivatives in anticancer therapy. Some of these compounds form noncovalent complexes with DNA (e.g., distamycin A, Hoechst 33258, and pentamidine) while others DNA‐binding compounds (such as CC‐1065) cause cleavages in the DNA backbone. In this article, we have reviewed the minor groove binders currently in preclinical evaluation in the last years. Diarylamidines such as DAPI, berenil, and pentamidine; bis‐benzimidazoles such as Hoechst 33258; ecteinascidins, pyrrololo [2,1‐c]‐[1,4]‐benzodiazepines (PBDs), CC‐1065, and distamycins are the classes discussed in this review article. A special section has been dedicated to hybrid molecules resulted by the combination of two minor groove binders, especially for derivatives of naturally occurring antitumor agents, such as anthramycin or the alkylating unit of the antibiotic CC‐1065, and distamycin frames. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 4, 475–528, 2004
On the evolution of thin viscous jets: filament formation
Authors: Fontelos Marco A. 
Published: April 2004

AbstractIn this paper, we have studied the evolution of thin fluid jets, paying special attention on the limit of very large viscosity. Local well‐posedness of the one‐dimensional system describing this evolution as well as the existence of break‐up (at least as t → ∞) under quite general conditions is proved. In addition, we have proved the well‐known experimental fact that in the limits of very large viscosities the solutions develop very long and thin filaments previous to break‐up and a complete detailed description of their structure is given. Copyright © 2004 John Wiley & Sons, Ltd.