bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impaired brain GABA in focal dystonia
Authors: Levy Lucien M. , Hallett Mark 
Published: October 2004

AbstractPatients with task‐specific dystonia (writer's cramp) have impaired cortical inhibition likely arising from striatal dysfunction. However, the levels of the inhibitory neurotransmitter gamma‐aminobutyric acid (GABA) in the brains of these patients are not known. In this study, we evaluated 7 patients with right‐sided focal, task‐specific dystonia and 17 normal control subjects. A novel method using two‐dimensional J‐resolved magnetic resonance spectroscopy revealed that brain GABA levels are decreased in specific brain regions of the focal dystonia patients compared to normal controls. A significant decrease in GABA level was observed in the sensorimotor cortex and lentiform nuclei contralateral to the affected hand, while there was only a small nonsignificant decrease in the ipsilateral sensorimotor cortex and lentiform nuclei. GABA changes in the posterior occipital region of patients were not significant. The impaired cortical GABA level correlates with prior physiologic studies showing reduced intracortical inhibition. Reduced GABA in the striatum is consistent with striatal dysfunction since GABA is a principal neurotransmitter in that region. The reduction of brain GABA in dystonia patients may explain the clinical symptomatology of focal dystonia. Magnetic resonance spectroscopy may be a useful noninvasive tool in the evaluation of regional brain GABA changes and in monitoring the effects of various therapies.
Studies of glycolysis of poly(ethylene terephthalate) recycled from postconsumer soft‐drink bottles. II. Factorial experimental design
Authors: Chen Cheng‐Ho , Chen Chuh‐Yean , Lo Yu‐Wen , Mao Ching‐Feng , Liao Wei‐Tung 
Published: October 2004

AbstractGlycolysis temperature, glycolysis time, and amount of catalyst are important factors affecting the glycolysis of recycled poly(ethylene terephthalate) (PET) flakes. A 23 factorial experimental design is applied to study the main, two‐factor interaction, and three‐factor interaction effects of glycolysis temperature, glycolysis time, and amount of catalyst on the glycolysis of recycled PET flakes. In this study cobalt acetate is used as the glycolysis catalyst. The sequence of the main effects on the glycolysis conversion of the recycled PET flakes in ascending order is glycolysis time < glycolysis temperature < amount of catalyst. The sequence of the two‐factor interaction effects on the glycolysis conversion of the recycled PET flakes in ascending order is glycolysis temperature versus the glycolysis time < glycolysis time versus the amount of catalyst < glycolysis temperature versus the amount of catalyst. The three‐factor interaction effect is significantly related to the glycolysis conversion of the recycled PET flakes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 956–962, 2001
Electromagnetic interference shielding effectiveness of ethylene vinyl acetate based conductive composites containing carbon fillers
Authors: Das N. C. , Chaki T. K. , Khastgir D. , Chakraborty A. 
Published: October 2004

AbstractConductive polymeric based composites were derived from ethylene vinyl acetate rubber filled with Vulcan XC‐72, short carbon fiber (SCF), and their blends. The electromagnetic interference (EMI) shielding effectiveness (SE), return loss, and reflection coefficient were studied. The measurements of the SE of the composites were carried out in two different frequency ranges of 100–2000 MHz and 8–12 GHz (X band). It was observed that the SE of the composites was frequency dependent and it increased with increasing frequency. The increasing of filler loading also enhanced the SE of the composites. The 100% SCF filled composites showed a higher SE compared to that of the filler blend or purely carbon black filled composites. The correlation between the SE and bulk conductivity of various composites was also discussed. The compromise between EMI SE, electrical conductivity, and mechanical properties was obtained when the composites contained both types of filler like particulate carbon black and SCF. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1601–1608, 2001
Preparation of poly(DL‐lactide‐co‐glycolide) nanoparticles without surfactant
Authors: Jeong Young‐Il , Cho Chong‐Su , Kim Sung‐Hyun , Ko Kyung‐Soo , Kim Sun‐Il , Shim Yong‐Ho , Nah Jae‐Woon 
Published: October 2004

AbstractThe preparation of poly(DL‐lactide‐co‐glycolide) (PLGA) nanoparticles was performed by a dialysis method without surfactant or emulsifiers. The size of the PLGA nanoparticles prepared from dimethylacetamide (DMAc) as an initial solvent was smaller than that from acetone. The sizes of the PLGA nanoparticles from DMAc and acetone were 200.4 ± 133.0 and 642.3 ± 131.1 nm, respectively. The effects of the initial solvent selected to dissolve the copolymer and the lactide:glycolide ratio were investigated. The PLGA nanoparticles were spherical as revealed by the results of scanning electron microscopy and transmission electron microscopy observations. From these results it was shown that PLGA nanoparticles could be formed by the dialysis method without surfactant. The drug‐loading contents and efficiency were also dependent on the lactide:glycolide ratio and initial feeding amount of the drug. A higher lactide ratio resulted in higher drug loading and higher loading efficiency. However, a higher initial feeding amount of the drug resulted in higher drug loading and lower loading efficiency. Clonazepam was released for at least 2 days and the release rate was slower with a higher lactide:glycolide ratio and a larger amount of drug‐loading nanoparticles than that with a lower lactide:glycolide ratio and a smaller amount of drug‐loading nanoparticles. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2228–2236, 2001
About the Lorentz correction used in the interpretation of small angle X‐ray scattering data of semicrystalline polymers
Authors: Cser F. 
Published: October 2004

AbstractLorentz correction is used to correct the intensities of X‐ray scattering of single crystal diffractometry in order to recalculate intensities to obtain structure factors. This correction reduces the intensities to zero at zero diffraction angle. Small angle scattering is used to study the dimensions of heterogeneities in polymeric materials. The scattering intensities near to zero scattering angle originate partly from periodic systems (reciprocal lattice) and partly from dispersed particle systems. Periodic systems should result in individual Gaussian or Lorentzian peaks with the position of a peak maximum depending on the length of the periodicity. Particle scattering results in a Gaussian peak centred at zero scattering angle. The effect of the Lorentz correction on the interpretation of small angle X‐ray scattering data is shown in the case of some semicrystalline polyethylenes (high density, linear low density, and low molecular weight waxy polyethylenes). The data are compared with those for amorphous block copolymers (styrene/butadiene) in which there is a periodic system with homogeneous lamellar thickness. Lorentz correction destroys the characteristics of the particle scattering and can be applied only for periodic systems. It should not be used to produce a peak on scattering data which does not show periodicity (peaks) without correction. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2300–2308, 2001
Indentation responses of a graded zirconium phosphate–filled epoxy resin
Authors: Low I. M. , Shi C. , Hussain M. , Yamaguch S. , Niihara K. 
Published: October 2004

AbstractThe effects of load and time on the Vickers indentation responses of a graded zirconium phosphate (ZP)–filled epoxy resin are described. The hardness of this material is dependent on the concentration of ZP dispersed within the epoxy matrix. In the region poor in ZP, the hardness response is independent of load. In contrast, the hardness response in the region rich in ZP is profoundly load‐dependent as a combined result of particle agglomeration and an indentation‐size effect. When compared with the ZP‐rich‐epoxy, the ZP‐poor epoxy exhibits a larger creep and a more pronounced elastic recovery in the Vickers impression. The nature and degree of deformation in the vicinity of Vickers contacts are also studied. During indentation the ZP‐rich epoxy exhibits no contact‐induced cracks but displays microscale plasticity, which can be associated with intergrain sliding, debonding, and grain push‐out. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 931–935, 2001
Synthesis of silicone–acrylic resins and their applications to superweatherable coatings
Authors: Park Hong‐Soo , Yang In‐Mo , Wu Jong‐Pyo , Kim Myung‐Soo , Hahm Hyun‐Sik , Kim Seong‐Kil , Rhee Hee‐Woo 
Published: October 2004

AbstractSilicone–acrylic resins were synthesized to prepare superweatherable paints for building materials. The raw materials used were n‐butyl acrylate, methyl methacrylate, and n‐butyl methacrylate as acrylic monomers and 3‐methacryloxypropyltrimethoxysilane (MPTS) as a silicone monomer reactive with the acrylic monomers. Acrylic copolymers were synthesized such that their glass‐transition temperatures were adjusted to 30°C and their MPTS contents were varied to 10, 20, and 30 wt %. As the content of silicone and MPTS increased, average molecular weight and viscosity increased, and thermal stability at high temperatures improved. When we tested the properties of coatings by blending the synthesized silicone–acrylic resins with a white pigment, adhesion was superior with various substrates, and their properties were suitable on the whole. Weatherability was tested by an outdoor exposure test with a weather‐ometer and an accelerated weathering tester, and their results showed that silicone–acrylic resin composed of 30 wt % MPTS was a superweatherable coating. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1614–1623, 2001
Measurement of water vapor transmission rate in highly permeable films
Authors: Hu Y. , Topolkaraev V. , Hiltner A. , Baer E. 
Published: October 2004

AbstractMeasurements of water vapor transmission rate (WVTR) are often based on the wet cup method described by ASTM E 96‐95. In attempting to compare the performance of thin polymer films with moderate to high water vapor permeability, it was observed experimentally that the ASTM method did not give reliable results for highly permeable films. In particular, the WVTR depended on film thickness and the ratio of film area to water surface area. It was determined that the high water vapor flux through the more permeable films caused a reduction in the driving force for water vapor transmission, that is, the relative humidity at the inner surface of the film. Consequently, the WVTR was underestimated. Comparisons based on a small area ratio and a constant small‐flux condition were considered as alternative approaches for evaluating performance using the wet cup method. The constant flux approach produced the best correlation with WVTR that was measured with a commercial instrument. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1624–1633, 2001
Preparation of PVDF hollow‐fiber membranes via immersion precipitation
Authors: Kong Jianfeng , Li K. 
Published: October 2004

AbstractPorous polyvinylidene fluoride (PVDF) hollow‐fiber membranes with high porosity were fabricated using the immersion precipitation method. Dimethylacetamide (DMAc) and N‐methyl‐2‐pyrrolidone (NMP) were used as solvent, respectively. In addition, polyvinylpyrrolidone (PVP), lithium chloride, and organic acids were employed as nonsolvent additives. The effects of the internal and external coagulation mediums on the resulting membrane properties were also investigated. The resulting hollow‐fiber membranes were characterized in terms of maximum pore radius, mean pore radius, effective surface porosity as well as wetting pressure. The structures of the prepared hollow fibers were examined using a scanning electron microscope. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1643–1653, 2001
Melamine salts as hardeners for urea formaldehyde resins
Authors: Weinstabl Andrea , Binder Wolfgang H. , Gruber Heinrich , Kantner Wolfgang 
Published: October 2004

AbstractVarious salts derived from melamine and organic acids were prepared and used as melamine substitutes for melamine urea formaldehyde (MUF) resins. The synthesis of these melamine salts and a detailed characterization of their stoichiometry are described. All salts form 1 : 1 or 1 : 2 stoichiometries in a homogeneous reaction. They crystallize during cooling of the hot and diluted reaction mixture. Both 13C–NMR and 15N–NMR data are reported and point toward the formation of real ionic structures. Most salts have higher water solubility than that of pure melamine and are tested for their ability to substitute melamine in MUF resins. The mechanical and chemical properties of plywood panels made up of traditional MUF resins and mixtures of UF resins with melamine salts are investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1654–1661, 2001
Chain orientation resulting from the crystallization under strain of poly(ϵ‐caprolactone) in miscible blends with poly(styrene‐co‐maleic anhydride)
Authors: Morin Dominique , Zhao Yue , Prud'Homme Robert E. 
Published: October 2004

AbstractAmorphous miscible blends of poly(ϵ‐caprolactone) (PCL) with a random copolymer of styrene–maleic anhydride (SMA) were stretched at room temperature and the crystallization of PCL was allowed to develop under strain. The crystallization of PCL, from oriented amorphous chains, leads to macroscopic crystalline chain orientation. Using infrared dichroism and wide‐angle X‐ray scattering techniques, it was found that the resultant crystalline orientation of PCL is always parallel to the strain direction, regardless of the experimental conditions, which is in contrast with the PCL/poly(vinyl chloride) blend, where both parallel and perpendicular chain orientations can be induced. Furthermore, the degree of crystalline orientation of PCL is influenced by the initial stretching‐induced amorphous chain orientation of the system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1683–1690, 2001
Impact fracture behavior of ethylene ionomer and structural change after stretching
Authors: Akimoto Hideo , Kanazawa Toshiaki , Yamada Masanobu , Matsuda Satoshi , Shonaike Gabriel O. , Murakami Atsushi 
Published: October 2004

AbstractWe carried out tensile impact test and very low speed tensile test on ethylene‐based Ionomers (E/15wt %MAA) to clarify the relation between impact toughness and high‐ordered structure. We also studied the changes in high‐ordered structure under deformation by observing Differential Scanning Calorimetory (DSC) and Small‐Angle X‐ray Scattering (SAXS) of fractured surface. Na Ionomers showed ductile fracture in both high speed tensile impact (3 m/s) and very low speed tensile (2 mm/min). The disappearance of secondary melting point (Ti) in Na Ionomers was due to the destruction of ordered structure surrounding the ionic aggregate. Similar behavior was observed in 60% (or less) neutralized Zn Ionomers. However, 80% neutralized Zn Ionomer showed brittle failure in high‐speed tensile impact, and Ti did not disappear. SAXS studies of Na and Zn Ionomers after fracture, show no change both after molding (no aging) and after aging. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1712–1720, 2001
Miniemulsion copolymerization of n‐butyl methacrylate with crosslinking monomers
Authors: Ghazaly H. Mohd. , Daniels E. S. , Dimonie V. L. , Klein A. , El‐Aasser M. S. 
Published: October 2004

AbstractMiniemulsion copolymerization of n‐butyl methacrylate and crosslinking monomers such as a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), or an aliphatic urethane acrylate macromonomer (AUA) was utilized to obtain crosslinked latex particles. The crosslinking monomers were added at 0.2 mol %, on the basis of the amount of n‐butyl methacrylate utilized in a polymerization. The development of the gel content during the copolymerization reaction differs depending on the type of the crosslinking monomer. In addition to the crosslinking reactions between the n‐butyl methacrylate and the crosslinking monomers, other kinetic events, such as microphase separation, may have occurred, giving rise to different particle morphologies, dependent on the type of initiator used (i.e., oil‐soluble or water‐soluble). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1721–1730, 2001
Development of graft copolymer flocculating agents based on hydroxypropyl guar gum and acrylamide
Authors: Nayak B. R. , Singh R. P. 
Published: October 2004

AbstractGraft copolymers of hydroxypropyl guar gum (HPG) with polyacrylamide (PAM) have been synthesized using a ceric ion‐induced solution polymerization technique at 28°C. Six graft copolymers have been synthesized with variation in the number and length of grafted PAM chains. The graft copolymers were characterized by viscometry, infrared (IR) spectroscopy, and thermal analysis studies. Flocculation jar tests were carried out in 0.25 wt % kaolin, iron ore, and silica suspensions. Among the series of graft copolymers, the one with fewest but longest PAM chains shows the better performance. The flocculation characteristics of this best performing graft copolymer are compared with various commercially available flocculants in the three suspensions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1776–1785, 2001
PP/clay nanocomposites: Effect of clay treatment on morphology and dynamic mechanical properties
Authors: Kodgire Pravin , Kalgaonkar Rajendra , Hambir Sangeeta , Bulakh Neelima , Jog J. P. 
Published: October 2004

AbstractThe morphology and properties of polypropylene (PP)/clay nanocomposites are described. The melt intercalation of organophilic clay was carried out with a single‐screw extruder. The effects of two kinds of treatments of clay are discussed. Maleic anhydride (MAH)‐grafted PP was used as a compatibilizer. The expansion of the intergallery distance of the clay was governed by the interaction between the clay treatment and the compatibilizer. In one case, the composites exhibited significantly reduced intensities of diffraction peaks, suggesting partial exfoliation of the clay layers, whereas for the second clay sample, expansion of the gallery height was noted. The mechanical properties of the PP/clay composites showed significant enhancement in their mechanical and thermal properties. About a 35% increase in the tensile modulus and about a 10% increase in the tensile strength were observed. The thermal degradation temperature increased from 270 to about 400°C as a result of the incorporation of clay, and the extent depended on the dispersion of clay in the composite. The most interesting outcome of this study was the changes in morphology for PP/clay composites, which are reported here for the first time. An optical microscopic study revealed that the PP/clay composites could be crystallized at higher temperatures than pure PP and that the morphology was remarkably altered because of the presence of layers of clay. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1786–1792, 2001
Synthesis, characterization, and adsorption properties of chitosan azacrown ethers bearing hydroxyl group
Authors: Yang Zhikuan , Yang Yuan 
Published: October 2004

AbstractTwo new chitosan azacrown ethers bearing hydroxyl groups (CTS‐DH and CTS‐DO) were synthesized by the reaction of 3‐hydroxyl‐1,5‐diaza‐cycloheptane and 3‐hydroxyl‐1,5‐diaza‐cyclooctane with epoxy‐activated chitosan. Their structures were characterized by elemental analysis, infrared spectra analysis, and X‐ray diffraction analysis. The adsorption and selectivity properties of the hydroxyl azacrown ethers chitosan derivatives for Ag+, Cr3+, Cd2+, and Pb2+ were also investigated. The experimental results showed that the two novel chitosan azacrown ethers have good adsorption capacity for Ag+, and also showed that the grafted chitosan azacrown ethers have high selectivity for the adsorption of Ag+ in the presence of Pb2+ and Cd2+. The selectivity coefficients of CTS‐DH and CTS‐DO were K = 21, K = 42, K = 20.5, K = 41, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1793–1798, 2001
Spontaneous spreading of emulsions on solid surfaces: Morphology and dynamics
Authors: Forester Jonathan E. , Sunkel Jorge M. , Berg John C. 
Published: October 2004

AbstractThe spontaneous spreading of emulsions of water dispersed in silicone oil onto glass surfaces is examined using differential interference contrast (DIC) microscopy. Spreading occurs via a precursor film from which the emulsion droplets are excluded. The radius of the interline of the bulk drop is found to vary as (time)1/10, as is commonly observed for the spontaneous spreading of pure liquids. The spreading rate constant decreases linearly with the volume percent of the dispersed phase, but drops suddenly to zero at approximately 73% dispersed phase. The width and spreading rate of the precursor film also is found to decrease with dispersed phase concentration. A fingering type of instability is evident at the leading edge of the precursor film, yet has little effect on the spreading rate of either the precursor film or the droplet interline. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1817–1825, 2001
Superabsorbent polymeric materials IX: Effect of cationic structure on swelling behavior of crosslinked poly(sodium acrylate‐co‐cationic monomers) in aqueous salt solutions
Authors: Lee Wen‐Fu , Huang Yu‐Lin 
Published: October 2004

AbstractTwo series of xerogels based on sodium acrylate (SA), trimethyl methacrylamidopropyl ammonium iodide (TMMAAI), trimethyl methacryloyloxyethyl ammonium iodide (TMMAI), and N,N′‐methylene‐bis‐acrylamide (NMBA) as a crosslinker were prepared by inverse suspension polymerization. The water absorbency and swelling kinetic behavior for these xerogels in water or various saline solutions were investigated. The results showed that the swelling behaviors of these absorbents are related to their chemical structures, their compositions, and the type of external salt solutions. There would be effective improvement in the water absorbency of these two gel series by copolymerizing SA with a small amount of cationic monomer (TMMAAI or TMMAI). The initial absorption rates in deionized water were found to be faster for TM series gels than for TA series gels. The two series of superabsorbents had a tendency to absorb water in dilute nitrate aqueous solutions in the order: Fe3+, Ni2+, Ca2+, Cu2+, and Na+ for Fe(NO3)3, Ni(NO3)2, Ca(NO3)2, Cu(NO3)2, and NaNO3 aqueous solution, respectively. The absorbency and initial absorption rate for these gels were related to the gel compositions and salt concentrations. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1827–1837, 2001