bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of branching on the thermal behavior of poly(butylene isophthalate)
Authors: Finelli Lara , Lotti Nadia , Munari Andrea 
Published: August 2002

AbstractThe thermal behavior of linear and randomly branched poly(butylene isophthalate) samples was investigated by thermogravimetric analysis and differential scanning calorimetry. As to the thermal stability, it was found to be good and similar for all the samples. The thermal analysis carried out using DSC technique showed that the melting temperature of the polymers decreased with increasing branching unit content, although the glass‐transition temperature was practically not affected by ramifications. The multiple endotherms typical of linear PBI were also observed in branched samples and were found to be influenced both by temperature and degree of branching. By applying the Hoffman‐Weeks' method, the equilibrium melting temperatures of the polymers were obtained. The presence of a crystal‐amorphous interphase was evidenced only for the branched samples and the interphase amount was found to increase as the branching unit content was increased. Isothermal melt crystallization kinetics was analyzed according to Avrami's treatment. The introduction of branching points was found to decrease the overall crystallization rate of poly(butylene isophthalate). Values of Avrami's exponent n close to 3 were obtained for all the samples, in agreement with a crystallization process originating from predetermined nuclei and characterized by three dimensional spherulitic growth. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2001–2010, 2002; DOI 10.1002/app.10517
Novel synthesis of diketocarboxymethyl‐celluose as bipolymer precursors
Authors: Khairou K. S. , Hassan R. M. , Shaker A. M. 
Published: August 2002

Abstract2,3‐Diketocarboxymethylcellulose was prepared by the oxidation of carboxymethylcellulose (CMC) with potassium permanganate in alkaline solutions (pH ≥ 12) with a yield of 98.1%. IR spectroscopy and microanalysis have elucidated the chemical structure of the synthesized macromolecule (CMCK). A tentative reaction mechanism for oxidation is suggested. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1019–1023, 2002
Highly efficient nucleating additive for isotactic polypropylene studied by differential scanning calorimetry
Authors: Marco C. , Gómez M. A. , Ellis G. , Arribas J. M. 
Published: August 2002

AbstractThe influence of an organic phosphate derivative in the crystallization of the monoclinic phase of isotactic polypropylene was studied by differential scanning calorimetry. To analyze the nucleation activity of the additive, the self‐nucleation process of the pure polymer was also studied by thermal techniques. A large increase in crystallization temperatures was obtained even for the lowest concentration of the additive, and its nucleating efficiency is the highest observed for α‐nucleating agents in isotactic polypropylene. The nucleating agent was also observed to increase the stability of the crystals formed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1669–1679, 2002; DOI 10.1002/app.10546
Effects of the crosslinking agent and diluents on bead properties of styrene–divinylbenzene copolymers
Authors: Kangwansupamonkon W. , Damronglerd S. , Kiatkamjornwong S. 
Published: August 2002

AbstractStyrene–divinylbenzene copolymer beads were synthesized by radical suspension polymerization. Effects of the divinylbenzene concentration and composition of the toluene/heptane diluent were studied regarding the polymer bead formation, surface morphology, solvent swelling ratio, and glass transition temperature. The crosslinking density and diluent composition were responsible for solvent swelling. Interaction between the polymer and the diluents is attributed to phase separation, which controls the formation of a network‐type or pore‐type polymer, or a combination. For an optimum bead swelling in toluene, a combined morphology of more flexible polymer networks and a small amount of pores is essential for the desired absorption–desorption behavior. This article also combines several current findings with work presented elsewhere to explain the bead formation phenomenon. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 654–669, 2002
Dicyanate ester–polyetherimide semi‐interpenetrating polymer networks. II. Effects of morphology on the fracture toughness and mechanical properties
Authors: Harismendy I. , Del Río M. , Marieta C. , Gavalda J. , Mondragon I. 
Published: August 2002

AbstractA high temperature thermosetting bisphenol‐A dicyanate (BADCy) was modified with polyetherimide (PEI) at various compositions. The effects of the morphology of the blends on the fracture toughness and mechanical properties were investigated. For this purpose, fracture, flexural, and compression tests were carried out. The fracture surfaces of the broken specimens were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The morphology was controlled by changing the curing conditions and PEI content. A good correlation between fracture properties and microstructural features of the mixtures has been observed. The phase‐inverted morphologies showed the highest fracture toughness, which was further increased by increasing the cure temperature. The mechanical properties of the matrix (modulus, yield strength) were not affected by the addition of the thermoplastic. Fracture energy values show similar trends for the different mechanical tests performed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2759–2767, 2001
UV photopolymerization behavior of dimethacrylate oligomers with camphorquinone/amine initiator system
Authors: Yu Q. , Nauman S. , Santerre J. P. , Zhu S. 
Published: August 2002

AbstractUltraviolet (UV)‐initiated polymerization of dimethacrylate oligomers with camphorquinone (CQ) and a tertiary amine as a radical photoinitiator system was studied using differential scanning calorimetry. Polymerization behavior of two curing systems, one glass‐forming and the other elastomer‐forming, were compared, based on the rate of polymerization and the double bond conversion. The radical termination in the glass‐forming system (E‐bis‐A DMA‐1) became diffusion controlled immediately upon exposure to UV radiation, with the reaction rate quickly reaching its maximum. The elastomer‐forming system (E‐bis‐A DMA‐2) polymerized at a much lower rate than E‐bis‐A DMA‐1 because of its lower methacrylate group content. The two systems introduced a different temperature dependence on the rate of polymerization. Increasing the temperature reduced the viscosity and enhanced chain segmental mobility. This delayed the autoacceleration in the glass‐forming system. Polymerization rates for both the curing systems increased with initiator concentration, but the dependence on CQ was only characterized by an exponential factor of <0.5. Presumably, this was due to primary radical recombination. The vinyl group conversion and gel fraction of E‐bis‐A DMA‐1 increased with the increase in CQ concentration and/or curing temperature, while the extent of reaction for E‐bis‐A DMA‐2 was relatively insensitive to the latter two factors. A large number of radicals were trapped inside the network of E‐bis‐A DMA‐1 after photocuring and they decayed slowly. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1107–1117, 2001
Influence of temperature, molecular weight, and molecular weight dispersity on the surface tension of PS, PP, and PE. I. Experimental
Authors: Moreira José Carlos , Demarquette Nicole Raymonde 
Published: August 2002

AbstractIn this work, the influence of temperature, molecular weight (M̄n), and molecular weight dispersity (MWD) on the surface tension of polystyrene (PS) was evaluated using the pendant drop method. The influence of temperature on the surface tension of isotatic polypropylene (i‐PP) and of linear low‐density polyethylene (LLDPE) was also studied here. It was shown that surface tension decreases linearly with increasing temperature for all the polymers studied. The temperature coefficient −dγ/dT (where γ is the surface tension, and T, the temperature) was shown to decrease with increasing molecular weight and to increase with increasing MWD. The surface tension of PS increased when the molecular weight was varied from 3400 to 41,200 g/mol. When the molecular weight of PS was further increased, the surface tension was shown to level off. The surface tension was shown to decrease with increasing molecular weight distribution. Contact angles formed by drops of diiomethane and water on films of PS with different molecular weights were measured at 20°C. The surface energies of those polymers were then evaluated using the values of the different pairs of contact angles obtained here using two different models: the harmonic mean equation and the geometric mean equation. It was shown that the values of the surface energy obtained are slightly less than are the ones extrapolated from surface‐tension measurements in the rubbery state. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1907–1920, 2001
Additive diffusion coefficients in polyolefins. II. Effect of swelling and temperature on the D = f(M) correlation
Authors: Reynier Alain , Dole Patrice , Feigenbaum Alexandre 
Published: August 2002

AbstractDiffusion coefficients of a large panel of molecules were experimentally measured in virgin polypropylene at 40 and 70°C and in swollen polypropylene at 40°C. The influence of mobility increase brought out by temperature or swelling are compared. The effects are more important for high molecular weight compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2434–2443, 2001
Study of the mechanical properties of mica‐filled polypropylene‐based GMT composite
Authors: Zhao Ruofei , Huang Jin , Sun Bin , Dai Gance 
Published: August 2002

AbstractMica‐filled polypropylene (PP)‐based GMT (PP–mica–GMT) was prepared by a double‐belt press and its mechanical properties were tested. The effect of the mica content on the mechanical properties of PP–mica–GMT was investigated. It was found that with a lower mica content in matrix the tensile and flexural properties were improved; however, at a high mica content level, the tensile and flexural properties decreased. With respect to the impact strength, there is a maximum value at an approximate 20 wt % mica content level. These results were attributed to the influence of mica on fiber–matrix adhesion. It is most likely that low mica content enhances fiber–matrix adhesion; however, high mica content is unfavorable to fiber–matrix adhesion. Maleic anhydride‐grafted PP (MPP) was used to enhance the fiber–matrix adhesion at a higher mica loading level for PP–mica–GMT. With increasing MPP content in the matrix, the tensile properties were significantly improved, whereas the Izod impact strength decreased. In addition, with 5 wt % MPP and 40 wt % mica in the PP matrix formulation, the effect of the mica particle size and glass fiber content on the mechanical properties of PP–mica–GMT was investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2719–2728, 2001
Laboratory instruction in histology at the University at Buffalo: Recent replacement of microscope exercises with computer applications
Authors: Cotter John R. 
Published: August 2002

AbstractHistology is a morphologic science in which the structure of the cells, tissues, and organs of the body are examined with a microscope. In the laboratory courses in histology at the School of Medicine of the University at Buffalo, histologic specimens had been used since the late 19th century to teach the principles of cell, tissue, and organ structure. Students also had to learn how to analyze or “read” slides with a microscope. Learning histology in this way, i.e., by direct examination of actual specimens, is time consuming and viewed by some as unnecessary. As a result of recent curricular reform at the School of Medicine that reduced contact time in histology, half of all laboratory exercises that would have been performed with a microscope were performed instead with interactive computer applications. By replacing some microscope exercises with more efficient computer applications, the histology course accommodated curricular change by both reducing contact time and continuing to offer valuable microscope laboratories for most of the organ systems of the body. To provide a basis for comparing traditional microscope exercises with computer‐assisted instruction in histology, the nature of the laboratory experience between 1846 and 1998 is briefly reviewed. The instructional strategy behind the use of computers is presented, along with the nature of the computer applications and the means by which the computer applications were incorporated into the school's laboratory course in histology. Anat Rec (New Anat) 265:212–221, 2001. © 2001 Wiley‐Liss, Inc.
It's ethical, but is it legal? Teaching ethics and law in the medical school curriculum
Authors: Olick Robert S. 
Published: August 2002

AbstractWhile Western medical ethics has ancient roots in the teachings of Hippocrates, its standing in the undergraduate medical curriculum is a distinctly modern development. Today, all of the 127 accredited U.S. medical schools offer formal biomedical ethics instruction, and nearly all offer instruction in the related discipline of health law. This article describes how biomedical ethics and health law are taught at the University of Iowa College of Medicine, one of 12 medical schools that offers separate required courses in both ethics and law. Often ethics and law overlap; often, to act ethically is to act legally. But medical students and practicing physicians also regularly confront dilemmas that pose the question, “It's ethical, but is it legal?” This article discusses the goals, methods, and core themes of teaching issues at the intersection of medicine, ethics, and law, and how the approach to this instruction is designed to offer students a tool kit to begin to deal effectively with these complex issues in professional life. Anat Rec (New Anat) 265:5–9, 2001. © 2001 Wiley‐Liss, Inc.
Hormonal activation of phosphorylase in cockroach fat body trophocytes: A correlation with trans‐membrane calcium flux
Authors: Steele J. E. , Ireland R. 
Published: August 2002

AbstractThis study is an investigation of the temporal relationship between transmembrane Ca2+ fluxes, and glycogen phosphorylase activation in dispersed trophocytes from the fat body of the cockroach, Periplaneta americana. Phosphorylase is maximally activated within 5 min after treating the trophocytes with either of the hypertrehalosemic hormones, Pea‐HTH‐I and Pea‐HTH‐II. Activation caused by Pea‐HTH‐II is sustained for a longer period than that produced by Pea‐HTH‐I. Chelation of extracellular Ca2+ with EGTA blocks the activation of phosphorylase by HTH. Similarly, chelation of intracellular Ca2+ with Quin 2 greatly diminishes the phosphorylase activating effect of both HTHs. The data support the view that an increase in the intracellular Ca2+ concentration is required for the activation of phosphorylase and that extracellular Ca2+ is an essential, although not necessarily sole, source of Ca2+ for this purpose. Using 45Ca2+ to trace the movement of Ca2+ following a challenge with either Pea‐HTH‐I or ‐II, it was shown that 45Ca2+influx nearly doubled during the first 30 s. At this time, the trophocytes begin to expel Ca2+ at a rate higher than that of untreated cells and this state persists for approximately 4 min. The Ca2+ fluxes are consistent with its postulated role in the activation of phosphorylase. Arch. Insect Biochem. Physiol. 42:233–244, 1999. © 1999 Wiley‐Liss, Inc.
Increased ribonucleotide reductase activity in hydroxyurea‐resistant mosquito cells
Authors: Gerenday Anna , Shih Karen M. , Herman Carter C. , Fallon Ann M. 
Published: August 2002

AbstractHydroxyurea‐resistant Aedes albopictus mosquito cells were selected by incremental exposure of unmutagenized cells to hydroxyurea concentrations ranging from 0.1 to 8 mM. Clonal populations that had become 40‐fold more resistant to hydroxyurea than wild‐type cells varied in morphology, and their growth rate decreased to a ˜45 h doubling time, relative to an 18 h doubling time in unselected cells. At this level of resistance, the cells remained diploid, with a modal chromosome number of 6. When labelled with 35S[methionine/cysteine], clone HU1062, which grew in the presence of 8 mM hydroxyurea, overproduced a labeled protein with the approximate size of the 45,000 dalton M2 subunit of ribonucleotide reductase. Consistent with this observation, ribonucleotide reductase activity in HU‐1062 cells was approximately 10‐fold higher than in wild‐type control cells. This is the first example of an hydroxyurea‐resistant insect cell line. Arch. Insect Biochem. Physiol. 34:31–41, 1997. © 1997 Wiley‐Liss, Inc.
Expression of neuroparsin cDNA in insect cells using baculovirus vectors
Authors: Girardie J. , Chaabihi H. , Fournier B. , Lagueux M. , Girardie A. 
Published: August 2002

AbstractThe cDNA encoding neuroparsin A, a polytropic neurohormone of the locust, Locusta migratoria, was inserted into the genome of Autographa californica nuclear polyhedrosis virus such that transcription was under control of the p10 promoter. A polypeptide having the same charge and the same apparent molecular weight as the authentic neuroparsin A and that was reactive against neuroparsin immune serum was produced in recombinant virus‐infected lepidopteran cell lines but not in control virus‐infected cells. The baculovirus‐expressed polypeptide was purified by two steps of liquid chromatography (anion exchange and reversed phase) which were previously used to purify the natural neuroparsin. The purified baculovirus‐expressed polypeptide enhanced fluid reabsorption of everted rectum preparations, as did the natural neuroparsin. Thus, this gene expression system produced a polypeptide identical to authentic neuroparsin. Arch. Insect Biochem. Physiol. 36:11–23, 1997. © 1997 Wiley‐Liss, Inc.
Magnetic resonance imaging of normal and osteoarthritic trabecular bone structure in the human knee
Authors: Beuf Olivier , Ghosh Srinka , Newitt David C. , Link Thomas M. , Steinbach Lynne , Ries Michael , Lane Nancy , Majumdar Sharmila 
Published: August 2002

AbstractObjectiveTo use high‐resolution magnetic resonance imaging (MRI) to evaluate the trabecular bone structure in the distal femur and the proximal tibia and its to correlate the findings with different stages of osteoarthritis (OA) of the human knee.MethodsAxial images of the distal femur and proximal tibia were obtained at 1.5 T in patients without and with mild OA and with severe OA. The spatial resolution was 195 × 195 μm2 with a 1‐mm slice thickness. Apparent measures of trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), trabecular separation (Tb.Sp), and trabecular thickness (Tb.Th) were calculated.ResultsSignificant differences existed in the trabecular bone structure of the femur and tibia. Differences in trabecular bone structure between the tibia and the femur decreased with the degree of OA. The apparent BV/TV, Tb.N, and Tb.Sp in the femoral condyles could be used to differentiate healthy patients or patients with mild OA from patients with severe OA (P < 0.05). Among individuals, the structural variation of the lateral and medial femoral condyle was indicative of the extent of the disease.ConclusionHigh‐resolution MRI of the knee joint can provide a noninvasive assessment of trabecular bone structure. Trabecular bone structure, determined by high‐resolution MRI, shows significant variation in patients with varying degrees of OA. The impact of OA on trabecular bone is different in the tibia than in the femur, and this difference depends on the extent of the disease.
Disposition and receptor‐site binding of 125I‐EGF after topical administration to skin wounds
Authors: Prats P.A. , Duconge J. , Valenzuela C. , Berlanga J. , Edrosa C.R. , Fernández‐Sánchez E. 
Published: August 2002

AbstractThe rhEGF topical delivery systems have been hindered by a number of shortcomings which have led to the search of new development strategies. In this study we report the evaluation of cumulative profiles of 10, 5 and 1 µg/ml solutions of 125I‐rhEGF, in a rat full‐thickness skin wound model, as well as the drug‐induced modulation in the expression of the EGF receptor after lesion. The tissue‐associated radioactivity, expressed as the percentage of the dose administered per grams of tissue (%D/g), peaks at 2 h after administration of all doses. 125I‐rhEGF degraded species were detected chromatographically, but no diffusion of the peptide to the surrounding skin was documented. Despite the dose, the EGF receptor expression was increased within 2 h after wounding, followed by a slow decline up to 12 h below baseline. Twelve hours after punch, differences were evident between all treated groups and control. These results demonstrate that 125I‐rhEGF saline solutions are rapidly cleared from application sites, probably by protease‐driven cleavage and receptor‐mediated endocytosis. Finally, we must be aware that the results herein discussed should be taken into account during the drug delivery system design in order to guarantee the necessary steady‐state rhEGF levels upon wound healing process. Copyright © 2002 John Wiley & Sons, Ltd.
50 Hz magnetic fields of varying flux intensity affect cell shape changes in invertebrate immunocytes: The role of potassium ion channels
Authors: Ottaviani Enzo , Malagoli Davide , Ferrari Alex , Tagliazucchi Davide , Conte Angela , Gobba Fabriziomaria 
Published: August 2002

AbstractThe effect induced by exposure to 50 Hz magnetic fields (MFs) in immunocytes from the mussel Mytilus galloprovincialis is evaluated. The whole animal was exposed for 15 and 30 min to MF intensities ranging from 200 to 1,000 μT. The changes in the cellular shape of immunocytes, expressed as shape factor (SF), were studied at different times after addition of the chemotacting substance N‐formyl‐Meth‐Leu‐Phe (fMLP). Results show that MFs provoke differing delays in fMLP‐induced cellular shape changes: 200 μT are ineffective, while levels from 300 μT upwards cause a significant increase in immunocyte SF values compared to controls. Reactivation of the cells is possible up to an intensity of 600 μT. The use of PCO 400, an opener of ATP‐sensitive K+ channels, shows that potassium channels are involved in the effect of MFs on M. galloprovincialis immunocytes. Bioelectromagnetics 23:292–297, 2002. © 2002 Wiley‐Liss, Inc.
Mammalian DNA single‐strand break repair: an X‐ra(y)ted affair
Authors: Caldecott Keith W. 
Published: August 2002

AbstractThe genetic stability of living cells is continuously threatened by the presence of endogenous reactive oxygen species and other genotoxic molecules. Of particular threat are the thousands of DNA single‐strand breaks that arise in each cell, each day, both directly from disintegration of damaged sugars and indirectly from the excision repair of damaged bases. If un‐repaired, single‐strand breaks can be converted into double‐strand breaks during DNA replication, potentially resulting in chromosomal rearrangement and genetic deletion. Consequently, cells have adopted multiple pathways to ensure the rapid and efficient removal of single‐strand breaks. A general feature of these pathways appears to be the extensive employment of protein–protein interactions to stimulate both the individual component steps and the overall repair reaction. Our current understanding of DNA single‐strand break repair is discussed, and testable models for the architectural coordination of this important process are presented. BioEssays 23:447–455, 2001. © 2001 John Wiley & Sons, Inc.