bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous interpenetrating networks consisting of polyurethane and graft vinyl ester resin: Effect of different radical initiators
Authors: Wang Gui You , Hu Chun Pu 
Published: October 2004

AbstractA series of well‐defined graft vinyl ester resins (graft VER), composed of butanol side chain (BO) or poly(oxypropylene) side chains with different molecular weights (200 or 390), were synthesized and characterized. The simultaneous interpenetrating networks (SINs) of graft VER and polyurethane (PU) were prepared. The effect of initiators for graft VER on the morphologies and mechanical properties of PU/graft VER SINs was studied through DSC, SEM, and FTIR observations. For PU/graft VER SIN formed with AIBN as initiator, the morphology and structure of these SINs are mainly controlled by the PU network formed first, and the structure of graft VER has almost no influence on the long‐range order structure of hard segments in SIN. For PU/graft VER SIN prepared with BPO/DMA as initiator (redox system), the side‐chain structure of graft VER greatly affects the morphologies of these SINs, although the PU network and graft VER network formed almost simultaneously. The reinforcement effect of the graft VER network on the PU network is significantly different by using these two different initiators for graft VER, which could be related with the morphologies of SINs and the formation rate of the two networks. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1629–1636, 2002; DOI 10.1002/app.10502
Nitroxide‐terminated poly(styrene‐co‐diethyl fumarates) and derived block copolymers
Authors: Lokaj J. , Holler P. , Kovár̆ová J. 
Published: October 2004

AbstractCopolymerization of styrene (S) and diethyl fumarate (DEF) at 125°C in the presence of 2,2,6,6‐ tetramethylpiperidin‐1‐yloxyl radical (TEMPO) and initiated with a thermal initiator, 2,2′‐azobisisobutyronitrile (AIBN), was studied. The molar fraction of DEF in the feed, FDEF, varied within 0.1–0.9. An azeotropic composition, (FDEF)A = 0.38, was found for the copolymerization under study. At FDEF = 0.1–0.4, a quasi‐living process was observed, transforming to a retarded conventional radical copolymerization at a higher content of DEF in the initial mixtures. The obtained TEMPO‐terminated S‐DEF copolymers were used to initiate polymerization of styrene. Poly(styrene‐ co‐diethyl fumarate)‐block‐polystyrene copolymers were prepared with molecular weight distributions depending on the amount of inactive polymer chains in macroinitiators, as indicated by size‐exclusion chromatography. A limited miscibility of the blocks in the synthesized block copolymers was revealed by using differential scanning calorimetry. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2432–2439, 2002
Comparative study of the nucleation activity of third‐generation sorbitol‐based nucleating agents for isotactic polypropylene
Authors: Marco C. , Ellis G. , Gómez M. A. , Arribas J. M. 
Published: October 2004

AbstractThe nucleation activity of the sorbitol derivatives 1,2,3,4‐bis(3,4‐dimethylbenzylidene sorbitol) and methyldibenzylidene sorbitol are compared with that of talc, a conventional nucleating agent for the monoclinic crystalline phase of isotactic polypropylene. The thermal parameters associated with the dynamic crystallization process are studied as a function of the cooling rate by differential scanning calorimetry, and the nucleating efficiency is assessed by comparison with self‐nucleation, the highest values being observed for 1,2,3,4‐bis(3,4‐dimethylbenzylidene sorbitol) over the whole concentration range. The nature of the polymer crystals formed in the nucleated polymer was studied by X‐ray diffraction, and the data show an increase in a preferred orientation of the polymer crystallites with increasing concentration of nucleating agent. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2440–2450, 2002
Sulfonation of polysulfones: Suitability of the sulfonated materials for asymmetric membrane preparation
Authors: Blanco J. F. , Nguyen Q. T. , Schaetzel P. 
Published: October 2004

AbstractThe effect of the starting polymer on the reaction of sulfonation of polysulfones was investigated. When concentrated sulfuric acid is used as the sulfonation reagent in an organic solvent‐free reaction, a polymer degradation equally occurs, leading to a decrease in the yield of product recovery. Poly(ether sulfone) Cardo appears to be the most resistant to chain scission in the medium and a control of the sulfonation degree can be performed via the reaction condition control. The reaction can be monitored by UV–Visible spectrophotometry. Phase inversion by immersion of a N‐methyl‐2‐pyrrolidone–polymer dope in water led to asymmetric membranes with an average pore size in the range of that of ultrafiltration and that of nanofiltration membranes. The latter membranes can only be obtained at high polymer concentrations and at moderate sulfonation degrees. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2461– 2473, 2002
Sorption properties of the composite fibers made of PAN and chitosan
Authors: Min Byung Ghyl , Kim Chang Whan 
Published: October 2004

AbstractA composite fiber of polyacrylonitrile (PAN) and chitosan was obtained by spinning the mixture of PAN/chitosan with a certain amount of diluted acetic acid as a plasticizer. Water plasticizes the PAN and acetic acid plasticizes the chitosan. The fiber showed a porous and fibrillar structure, which could be converted easily into pulplike short fiber by pulping. PAN/chitosan pulp showed a much higher amount of uptake for acid dye than that of either powdery chitosan or activated carbon. It is considered that this better sorption capacity of the composite fiber results from the relatively large surface area attributed to its pulplike shape. The adsorption behavior of the composite fiber was considerably affected by temperature and pH because the adsorption is exothermic and proceeds by an acid–base reaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2505–2511, 2002
Studies on microwave shielding materials based on ferrite‐ and carbon black‐filled EPDM rubber in the X‐band frequency
Authors: Annadurai P. , Mallick A. K. , Tripathy D. K. 
Published: October 2004

AbstractThe preparation and characterization of ferrite‐ and carbon black‐filled ethylene‐propylene‐ethylidene norborene terpolymer rubber composites were studied for microwave applications. Both the insertion loss and return loss were measured in a high‐frequency range (X‐band) with a network analyzer. The results indicated a relatively low frequency dependence. The difference in the insertion losses measured for all samples, except for one containing 100 phr ferrite and 75 phr carbon black (B75), was ±3 dB. Sample B75 showed broadband absorption in the aforementioned frequency band. Furthermore, the incorporation of both ferrite and carbon black powder into the rubber matrix altered the electrical and microwave properties, that is, the insertion loss and return loss; this could be helpful in the design of suitable absorbing materials for microwave applications at high frequencies. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 145–150, 2002
Adhesive and anticorrosive properties of poly(vinylidene fluoride) powders blended with phosphonated copolymers on galvanized steel plates
Authors: Bressy‐Brondino Christine , Boutevin Bernard , Hervaud Yves , Gaboyard Manuel 
Published: October 2004

AbstractFluoropolymers with adhesive and anticorrosive properties were investigated by blending statistical phosphonated copolymers with poly(vinylidene fluoride) (PVDF). In a first part, methacrylic monomers bearing dialkyl phosphonate and phosphonic acid groups were synthesized. Dimethyl(2‐methacryloyloxyethyl)phosphonate was obtained by carrying out a one‐step methacrylation of a commercial phosphonated alcohol. Then, a chemical conversion of the dimethyl phosphonate group to phosphonic acid groups was accomplished by two routes, including on the one hand a trimethylhalosilane and on the other hand an inorganic halide as dealkylation reagents. The resulting monomers were analyzed by nuclear magnetic resonance (NMR) spectroscopy and results were discussed. In a second part, the phosphonated monomers were copolymerized with methyl methacrylate in the presence of 2,2'‐azobis(isobutyronitrile) (AIBN) to give statistical copolymers in high yields. In a third and last part, copolymers were introduced into PVDF as adhesion promoters and anticorrosion inhibitors. Good dry and wet adhesion properties onto galvanized steel plates were obtained with blends containing mainly phosphonic acid groups. Results of corrosion tests show that the phosphonic acid groups maintain some level of adhesion, thereby preventing the spread of corrosion. However, the number of acid groups and their neighbors influence the adhesive and anticorrosive properties of the PVDF coatings. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2277–2287, 2002
Adipogenic healing in adult mice by implantation of hollow devices in muscle
Authors: Xaymardan Munira , Gibbins John R. , Zoellner Hans 
Published: October 2004

AbstractIn mammals, wound healing is thought to result in the formation of scar tissue, with the exception of bony healing after fractures. Here we describe a previously unknown pattern of wound healing in which adipose rather than scar tissue is formed. Adipogenesis is normally confined to the embryo, although there are several experimental models for adipogenesis with highly specific dietary, cytokine, matrix, sex, or age requirements. The adipogenic healing described in this work provides a simple and reproducible experimental mouse model for adipogenesis without these limitations. Mice received intramuscular implants of nylon mesh material. Fibrinous material impregnated implants and within 4 weeks was replaced with highly vascular granulation tissue, typical of wound healing. Also consistent with wound healing was a reduction in vascularity of the newly formed tissue over time (P < 0.05). Lipoblasts were prevalent in granulation tissue, reaching a maximum in week 2 (P < 0.001) but falling to very low levels by week 9. These cells matured to adipocytes, with intermediate forms being seen. The identity of lipoblasts and adipocytes was confirmed by Oil Red O staining and electron microscopy. Control experiments confirmed that adipogenesis was independent of the materials used as well as of the sex and age of the animals. Rather, adipogenesis appeared to be due to replacement of fibrinous material in a space created within muscle. It is possible that adipogenic healing represents an adaptation for limiting the formation of restrictive scar tissues within muscle, and that this is the basis for the formation of traumatic lipomas in humans. Also, muscle tissue is replaced by adipose cells, seemingly derived from pluripotential satellite cells, in several degenerative muscle conditions, suggesting a role for adipogenic healing in these conditions. Anat Rec 267:28–36, 2002. © 2002 Wiley‐Liss, Inc.
Approaches to studying cellular signaling: A primer for morphologists
Authors: Hartford Svoboda Kathy Kay , Reenstra Wende R. 
Published: October 2004

AbstractMany research projects will lead to understanding tissue and/or cell responses to extracellular influences either from soluble factors or the surrounding extracellular matrix. These types of investigations will require the understanding of signal transduction. This particular cell biological field has literally exploded with information and new technical approaches in the past 10 years. This article is directed toward investigators interested in using these new approaches to study their systems. An overview of the general principles of signal transduction events including the types of receptors and intracellular signaling events is followed by an introduction to methods for visualizing signal transduction. This is followed by an introduction to biochemical analysis and an example of combining several approaches to understanding a tissue response to extracellular matrix stimulus. Anat Rec (New Anat) 269:123–139, 2002. © 2002 Wiley‐Liss, Inc.
Integrated approach to teaching and testing in histology with real and virtual imaging
Authors: Heidger Paul M. , Dee Fred , Consoer Daniel , Leaven Timothy , Duncan James , Kreiter Clarence 
Published: October 2004

AbstractThe University of Iowa College of Medicine histology teaching laboratory incorporates extensive Web‐ and computer‐based teaching modalities, including the Virtual Microscope (VM), as emerging learning aids in histology and pathology laboratory instruction. We report here our experience in offering a multiple resource‐based approach to laboratory instruction while retaining the opportunity and requirement of examining actual microscopic slide preparations with the microscope. Acceptance of this approach has been high among our students and faculty, and performance levels established over years of teaching histology by traditional means have been maintained. Anat Rec (New Anat) 269:107–112, 2002. © 2002 Wiley‐Liss, Inc.
Morphological effects in the mouse myocardium after methylenedioxymethamphetamine administration combined with loud noise exposure
Authors: Gesi Marco , Lenzi Paola , Soldani Paola , Ferrucci Michela , Giusiani Alberto , Fornai Francesco , Paparelli Antonio 
Published: October 2004

AbstractEarly toxicity occurring during or immediately after 3,4‐methylenedioxymethamphetamine (MDMA, or “ecstasy”) administration has not been investigated in detail, although in humans it is responsible for marked side effects, and even death. Acute toxicity induced by MDMA produces rhabdomyolysis involving the myocardium (myocytolysis). Cardiac symptoms, such as tachycardia, hypertension, and arrhythmia, are present to a variable extent in humans abusing ecstasy. In most cases, this substance is abused in the presence of loud noise, which may affect the myocardium. Despite the frequency of the concomitant exposure to ecstasy and loud noise, and the similarities between the early side effects of these two agents, to our knowledge no study has investigated the role of loud noise in modulating MDMA toxicity. Therefore, in the present study, we evaluated whether cardiac effects of MDMA administration following a typical “binging” pattern are enhanced by concomitant exposure to loud noise. We selected low doses of MDMA in order to avoid gross morphological alterations, or lesions detectable under light microscopy. The myocardial alterations observed were visible only at the ultrastructural level. We found a dramatic enhancement of alterations in the mouse heart upon MDMA administration during loud noise exposure. Remarkably, this enhancement was evident both as a decrease in the threshold dose of MDMA necessary to alter the myocardial ultrastructure, and as an increase in myocardial alterations produced by a higher dose of MDMA. Anat Rec 267:37–46, 2002. © 2002 Wiley‐Liss, Inc.
Scanning electron microscopy study of the tongue and lingual papillae of the california sea lion (Zalophus californianus californianus)
Authors: Yoshimura Ken , Shindoh Junji , Kobayashi Kan 
Published: October 2004

AbstractWe observed the three‐dimensional structures on the external surface and the connective tissue cores (CTCs) of the California sea lion (Zalophus californianus californianus), after exfoliation of the epithelium of the lingual papillae (filiform, fungiform, and vallate papillae), using scanning electron microscopy (SEM) and conventional light microscopy. Macroscopically, the tongue was V‐shaped and its apex was rounded. At the posterior area of the tongue, five vallate papillae were arranged in a V shape. In the epithelium, numerous taste buds were distributed on the top of the vallate papillae. On the dorsal surface from the apex to the boundary between the anterior and posterior tongue, filiform papillae were densely distributed. The CTCs of the filiform papillae consisted of a main protrusion (primary core) and many small cores (secondary cores). From the apex to the anterior one‐third of the tongue, dome‐like fungiform papillae were densely distributed, whereas fewer were located at the posterior two‐thirds of the tongue. Several taste buds were found in the epithelium on the fungiform papillae. The size of the filiform papillae gradually increased from the apex to the boundary between the anterior and posterior tongue. At the lingual radix, the conical papillae, which were bigger than any filiform papillae, were densely distributed. The morphological characteristics of the tongue of the California sea lion appear to have been transformed to adapt to an aquatic environment; however, they possess some structures similar to those of land mammals. Anat Rec 267:146–153, 2002. © 2002 Wiley‐Liss, Inc.
Branching, segmentation and the metapterygial axis: pattern versus process in the vertebrate limb
Authors: Cohn M.J. , Lovejoy C.O. , Wolpert L. , Coates M.I. 
Published: October 2004

AbstractExplanations of the patterns of vertebrate fin and limb evolution are improving as specific hypotheses based on molecular and developmental data are proposed and tested. Comparative analyses of gene expression patterns and functions in developing limbs, and morphological patterns in embryonic, adult and fossil limbs point to digit specification as a key developmental innovation associated with the origin of tetrapods. Digit development during the fin‐to‐limb transition involved sustained proximodistal outgrowth and a new phase of Hox gene expression in the distal fin bud. These patterning changes in the distal limb have been explained by the linked concepts of the metapterygial axis and the digital arch. These have been proposed to account for the generation of limb pattern by sequential branching and segmentation of precartilagenous elements along the proximodistal axis of the limb. While these ideas have been very fruitful, they have become increasingly difficult to reconcile with experimental and comparative studies of fin and limb development. Here we argue that limb development does not involve a branching mechanism, and reassess the concept of a metapterygial axis in limb development and evolution. BioEssays 24:460–465, 2002. © 2002 Wiley Periodicals, Inc.
The role of DNA replication in chromosome condensation
Authors: Pflumm Michelle F. 
Published: October 2004

AbstractAt metaphase, DNA in a human chromosome is estimated to be compacted at least 10,000 fold in length.1,2 However, the higher order mechanisms by which the chromosomes are organized in interphase and subsequently further condensed in mitosis have largely remained elusive. One generally overlooked participant in chromosome condensation is DNA replication. Many early studies of eukaryotic chromosome organization and cell fusions have suggested that DNA replication plays a role in chromosome compaction. Recent phenotypic analysis of Drosophila DNA replication mutants has revitalized this old idea. In this review, the role of DNA replication in chromosome condensation will be examined. BioEssays 24:411–418, 2002. © 2002 Wiley Periodicals, Inc.
Effect of molecular confinement on internal enzyme dynamics: Frequency domain fluorometry and molecular dynamics simulation studies
Authors: Bismuto Ettore , Martelli Pier Luigi , De Maio Anna , Mita Damiano Gustavo , Irace Gaetano , Casadio Rita 
Published: October 2004

AbstractThe tryptophanylemission decay of the mesophilic β‐galactosidase from Aspergillus oryzae free in buffer and entrapped in agarose gel is investigated as a function of temperature and compared to that of the hyperthermophilic enzyme from Sulfolobus solfataricus. Both enzymes are tetrameric proteins with a large number of tryptophanyl residues, so the fluorescence emission can provide information on the conformational dynamics of the overall protein structure rather than that of the local environment. The tryptophanyl emission decays are best fitted by bimodal Lorentzian distributions. The long‐lived component is ascribed to close, deeply buried tryptophanyl residues with reduced mobility; the short‐lived one arises from tryptophanyl residues located in more flexible external regions of each subunit, some of which are involved in forming the catalytic site. The center of both lifetime distribution components at each temperature increases when going from the free in solution mesophilic enzyme to the gel‐entrapped and hyperthermophilic enzyme, thus indicating that confinement of the mesophilic enzyme in the agarose gel limits the freedom of the polypeptide chain. A more complex dependence is observed for the distribution widths. Computer modeling techniques are used to recognize that the catalytic sites are similar for the mesophilic and hyperthermophilic β‐galactosidases. The effect due to gel entrapment is considered in dynamic simulations by imposing harmonic restraints to solvent‐exposed atoms of the protein with the exclusion of those around the active site. The temperature dependence of the tryptophanyl fluorescence emission decay and the dynamic simulation confirm that more rigid structures, as in the case of the immobilized and/or hyperthermophilic enzyme, require higher temperatures to achieve the requisite conformational dynamics for an effective catalytic action and strongly suggest a link between conformational rigidity and enhanced thermal stability. © 2002 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 67: 85–95, 2002
Aggregation characteristics of ovalbumin in β‐sheet conformation determined by spectroscopy
Authors: Sabaté Raimon , Estelrich Joan 
Published: October 2004

AbstractProtein misfolding and aggregation are involved in a number of the so‐called “conformational” diseases (e.g., transmissible spongiform encephalopathies and Alzheimer disease). The development of rational strategies to interfere with aggregation is a potential therapeutic approach that requires complete knowledge of the aggregation process. We studied the aggregation of ovalbumin in β‐sheet conformation using mainly the spectral changes in the spectra of two dyes (Congo Red and pinacyanol) caused by the aggregates. We assumed a linear model of polymerization that fit to the experimental data. The critical aggregation constant, concentration of half‐aggregation, nucleation parameter, growth parameter, and number of aggregation and free energy changes (total and per residue) were determined as aggregation‐related parameters. β‐Ovalbumin aggregates in a cooperative way. Moreover, the differences between such parameters obtained with Congo Red and pinacyanol suggest that each dye interacts with the protein in its own way. © 2002 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 67: 113–120, 2002
New cross‐linked and sulfated derivatives of partially deacetylated hyaluronan: Synthesis and preliminary characterization ;
Authors: Crescenzi Vittorio , Francescangeli Andrea , Renier Davide , Bellini Davide 
Published: October 2004

AbstractPartial chemical deacetylation of hyaluronan (HA) has been carried out using known procedures and carefully controlled experimental conditions in order to minimize chain degradation. The sample described herein (deHA) has a degree of deacetylation of about 17%, which corresponds to what required for its further use, but a molecular weight of about 1/25 with respect to the native, starting material. Chemical gels have been prepared with different degrees of cross‐linking by means of a Ugi multicomponent condensation reaction involving aqueous deHA, formaldehyde, and cyclohexylisocyanide: the gels are mechanically stable and exhibit good water uptake strongly dependent on the extent of cross‐linking, as expected. deHA samples have also been selectively N‐sulfated or O‐sulfated: the former exhibit anticoagulant properties well exceeding those of the latter and not too inferior to heparin. © 2002 Wiley Periodicals, Inc. Biopolymers 64: 86–94, 2002