bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interaction of cognitive aging and memory deficits related to epilepsy surgery
Authors: Helmstaedter Christoph , Reuber Markus , Elger Christian C. E. 
Published: October 2002

AbstractTemporal lobe epilepsy surgery can cause significant memory impairment. This study was intended to examine whether surgery also could affect prognosis of memory in older age. Age regression of verbal memory was examined in 187 patients (before and 1 year after left temporal lobe surgery) and 264 healthy controls. Eighty patients underwent selective amygdalohippocampectomy, and 107 patients underwent anterior two‐thirds temporal lobectomy. Amygdalohippocampectomy patients had mesiotemporal epilepsy; anterior two‐thirds temporal lobectomy patients had more extramesial or diffuse seizure onset zones. Memory was assessed by word list learning for its more mesial (consolidation/retrieval) and more neocortical (learning) aspects. Patients showed significant preoperative memory impairment. Independent of seizure outcome and surgical approach, surgery had significant negative effects on learning and consolidation/retrieval. In the amygdalohippocampectomy group, preoperative and postoperative age regressions of learning and consolidation/retrieval were not different from those of controls. In the anterior two‐thirds temporal lobectomy group, age regression of verbal learning became steeper after surgery, and consolidation/retrieval was negatively correlated with older age and later onset of epilepsy even before surgery. The data confirm that age regression of verbal memory in left temporal lobe epilepsy is similar to that in healthy controls. Both left anterior two‐thirds temporal lobectomy and amygdalohippocampectomy worsen verbal learning and memory and bring patients closer to cognitive disability. Particularly in anterior two‐thirds temporal lobectomy patients, surgery and reduced capacities for compensation cause acceleration of lifetime memory decline. The results support earlier and tailored epilepsy surgery and suggest that memory prognosis in older age should be considered if more extensive temporal resections would be inevitable.
The effects of alkaline earth dehydroabietate on the crystallization process of polypropylene
Authors: Li Chun‐Cheng , Zhang Dong , Li Zhen‐Yi 
Published: October 2002

AbstractIn this article, the influence of alkaline earth dehydroabietates, which were prepared from Na‐dehydroabietate, on crystallization of polypropylene (PP) from the melt state was studied by differential scanning calorimetry and polarization microscopy. It was found that magnesium dehydroabietate could improve mechanical properties and crystallization temperatures of PP and also decrease the size of spherulites. Kinetic analysis of PP isothermal crystallization showed that magnesium dehydroabietate decreased the fold surface energy of the developing crystals of PP and promoted the nucleation and crystallization of PP. However, calcium dehydroabietate increased the fold surface energy of the developing crystals of PP, but had no nucleation effect on PP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2644–2651, 2002
Investigation of loading and release in PVA‐based hydrogels
Authors: Ruiz J. , Mantecón A. , Cádiz V. 
Published: October 2002

AbstractWe used Methylene Blue (MB) and Methyl Orange (MO) as model drugs to investigate the controlled release behavior of hydrogels from poly(vinyl alcohol) crosslinked with ethylenediaminetetraacetic dianhydride. The cationic or anionic character of these compounds and the molecular weight between crosslinks of the hydrogel and the concentration of ionizable groups in the hydrogel greatly affected the loading and release of the drugs. MB loading was favored, therefore, by a higher content of negative charges in the hydrogel, although this implied a greater degree of crosslinking and, therefore, a lower mesh size. On the other hand, the overall loading of negative MO, favored by a higher mesh size, was very low because of unfavorable interactions with the electrolyte charges. Release studies showed that one of the parameters that most affected the drug release behavior of these hydrogels was the pH of the solution. MB and MO were not completely released, even at pH 1. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1644– 1651, 2002.
The leaching kinetics of acetone in an acetone‐polyurethane adhesive waste
Authors: Font R. , Sabater M. C. , Martínez M. A. 
Published: October 2002

AbstractThis work consists of the study of the extraction of solvent (acetone) from a polymeric (polyurethane) substrate during a leaching process. Total organic carbon (T.O.C.) is the main contaminant parameter in the leaching of these systems due to the solution of the acetone which is practically totally extracted from the polymeric system. During the leaching process, the water (polar) diffuses across the holes formed between the chains of polyurethane reacting at the same time with the isocyanate groups at the end of the chains, causing the reticulation or crosslinking of the polymer. On the basis of the experimental results, the amount of acetone diffused versus time in plane sheet systems was studied. A diffusion model based on the Fickian law was developed considering two stages. In the first stage, the water diffuses into the system across the polyurethane chains causing the reticulation of the polymer and dissolving the acetone. In the second stage, the diffusion of acetone in water, which occupies the holes or spaces between the reticulated polymer, takes place. The diffusion kinetics in these kinds of systems are similar to the diffusion kinetics in a rigid solid, considering an effective diffusivity of the acetone through the system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1945–1955, 2002
Curing and combustion properties of a PU‐coating system with UV‐reactive phosphazene
Authors: Huang Woei‐Kae , Chen Kwei‐Ju , Yeh Jen‐Taut , Chen Kan‐Nan 
Published: October 2002

AbstractA UV‐curable polyurethane (PU)‐coating system containing phosphorus is formulated by the combination of photoinitiator, PU acrylate oligomer, and UV‐reactive phosphazene monomer. PU acrylate oligomer is prepared by the addition of 2‐hydroxyethylmethacrylate (HEMA) to NCO‐terminated PU prepolymer. UV‐reactive phosphazene monomer is derived from the HEMA substitution reaction to hexachlorocyclotriphosphazene (NPCl2)3. The curing reaction of this PU‐coating system is carried out by UV irradiation. The resultant UV‐cured PU‐coated films demonstrated better performance properties than those of original UV‐cured PU acrylate (UV‐PU) without UV‐reactive phosphazene monomer. Furthermore, their thermal properties are investigated by a thermogravimetric analyzer and a dynamic mechanical thermal analyzer, respectively. The combustion behaviors of these UV‐cured PU‐coated films are evaluated by the measurements of a limiting oxygen index and a cone calorimeter. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1980–1991, 2002
Surface modification of poly‐L‐lactide by photografting of hydrophilic polymers towards improving its hydrophilicity
Authors: Ma Zuwei , Gao Changyou , Yuan Jun , Ji Jian , Gong Yihong , Shen Jiacong 
Published: October 2002

AbstractPoly‐L‐lactide (PLLA) has been used to prepare scaffolds to guide tissue regeneration in tissue engineering research. However, one of the limitations to the use of PLLA as an ideal biomaterial is its high hydrophobicity. To improve the hydrophilicity of PLLA, hydrophilic polymers were grafted onto PLLA membrane surfaces through the combination of photooxidization in hydrogen peroxide and subsequent ultraviolet (UV)‐induced grafting copolymerization in the monomer solution. Three kinds of modified PLLA membranes (i.e., PLLA‐g‐polyhydroxyethyl methacrylate, PLLA‐g‐polyacrylamide, and PLLA‐g‐polymethacrylic acid) were obtained, resulting in the more wettable PLLA membranes. The occurrence of the grafting polymerization was confirmed by attenuated total reflectance infrared spectroscopy (ATR‐IR) and X‐ray photoelectron spectroscopy (XPS) analysis. Surface morphology of the modified PLLA membranes was studied by scan electronic microscopy (SEM). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2163–2171, 2002
The conductivity behavior of multi‐component epoxy, metal particle, carbon black, carbon fibril composites
Authors: Jia W. , Tchoudakov R. , Joseph R. , Narkis M. , Siegmann A. 
Published: October 2002

AbstractFollowing the previous studies of epoxy/silver conductive composites, a detailed investigation of the influence of ethylene glycol on the resulting resistivity of various composites was carried out. Ethylene glycol was found to have a catalytic effect on the curing process of the epoxy resin, verified by differential scanning calorimetry studies. The accelerated curing process diminishes settling of the metal particles and therefore results in better and more uniform conductivities. High temperature curing of the composites was found to have a similar effect on the conductivity. The conductivity behavior of some other composites, such as epoxy/nickel, epoxy/nickel/carbon fibrils, and epoxy/carbon black/carbon fibrils, were also studied. The structure–property relations were better understood through scanning electron microscopy observations. Silver and nickel particles were found to perform differently in the cured epoxy, showing different percolation concentrations and conductivity levels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1706–1713, 2002
On the thermal degradation of poly(styrene sulfones). VII. Evaluations of poly(styrene sulfone) thermal stability using invariant kinetic parameters
Authors: Yang Mu‐Hoe 
Published: October 2002

AbstractThe thermal degradation behavior of poly(styrene sulfone) was investigated by thermogravimetric analysis (TGA) measurement. This study described its thermal stability by applying the invariant kinetic parameter (IKP) method. The thermogravimetric and differential thermogravimetric analyses of different compositions of poly(styrene sulfones) were carried out over the temperature range 100–500°C under nitrogen. The kinetic parameters (preexponential factor and activation energy) of thermal decomposition of poly(styrene sulfone) can be obtained by dynamic measurement of TGA. The IKP method assumes that the kinetic parameters are independent of the experimental conditions. These parameters are computed without any hypothesis on the form of the kinetic degradation function. Invariant activation energies of the degradation of poly(styrene sulfone) show that the thermal stability decreases as the SO2 content of poly(styrene sulfone) increases due to the thermal instability of the CS bond. The relation equation, Eainv = 237.0 − 290.5XSO2, where XSO2 is the molecular fraction of SO2, was obtained to describe the effect of sulfur dioxide on the thermal stability of poly(styrene sulfone). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1698–1705, 2002
Radiation effects on HDPE/EVA blends
Authors: Dalai Siqin , Wenxiu Chen 
Published: October 2002

AbstractIn this article, we discuss the radiation effects of high‐density polyethylene (HDPE)/ethylene–vinyl acetate (EVA) copolymer blends. In comparison with the low‐density polyethylene/EVA blends, the EVA content in the HDPE/EVA blends had a lower enhancement effect on radiation crosslinking by γ‐ray irradiation in air. The phenomenon is discussed with the compatibility, morphology, and thermal properties of HDPE/EVA blends. The HDPE/EVA blends were partly compatible in the amorphous region, and radiation crosslinking of the HDPE/EVA blend was less significant, although increasing the amorphous region's content of the HDPE/EVA blends and the vinyl acetate content of EVA were beneficial to radiation crosslinking. The good compatibility was a prerequisite for the enhancement effect of EVA on the radiation crosslinking of the polyethylene/EVA copolymer. The radiation crosslinking and the degradation mechanism of HDPE/EVA blends were examined quantitatively by a novel method, the step analysis process of irradiated HDPE/EVA blends with a thermal gravimetric analysis technique. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 553–558, 2002
Kinetics of polymerization and particle stabilization mechanism on dispersion copolymerization of styrene and divinylbenzene
Authors: Zhang Hong Tao , Huang Jin Xia , Jiang Bing Bing 
Published: October 2002

AbstractMonodisperse highly crosslinked microspheres were prepared by dispersion copolymerization of styrene and divinylbenzene in an ethanol/water medium using poly(N‐vinylpyrrolidone) (PVP) as the stabilizer. The locus of polymerization and growth of particles were investigated. The polymerization kinetics, average particle diameter (Dn), polydispersity index (PDI), and numbers of particles (Np) were presented. When the initial styrene concentration is below 20%, the results indicate that the polymerization occurs in the particles, and the particles grow to their final size by the diffusion of monomer and oligomer into the existing particles. The polymerization rate can be described by the equation Rp = k[l]0.87 ([St]1.91 + [DVB]0.09) (1 + [PVP]0.01) exp(− 45.35/RT). The data from infrared spectroscopy demonstrated that the graft stabilizer was present. The dissolution experiments show that the crosslinking reaction occurred irregularly in batch dispersion polymerization. Using the postaddition approach, up to 3% divenylbenzene (DVB) was successfully incorporated in the synthesis of coagulum‐free substance, and monodisperse crosslinked 5 μ m microspheres with a superior resistance to solvents have been prepared. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2230–2238, 2002
Influence of synergists: The influence of hydroperoxide decomposers on phenolic inhibitors consumption in oxidized polypropylene
Authors: Shanina E. L. , Zaikov G. E. , Fazlieva L. K. , Bukharov S. V. , Mukmeneva N. A. 
Published: October 2002

AbstractThe influence of sulphur‐ and phosphorum‐containing substances (hydroperoxide decomposers) on the kinetics of the consumption of two phenolic antioxidants in polypropylene (PP) was studied. The induction periods of PP autoxidation at 130°C were measured in the presence of inhibiting compositions that consisted of phenolic inhibitors and decomposers of hydroperoxide. Obtained results indicated that the influence of the hydroperoxide decomposer became significant when the concentration of the phenolic antioxidant became close to critical value. It also was shown that the efficiency of the hydroperoxide decomposer significantly depended on the mechanism of the transformation of the phenolic inhibitor; and first of all on the nature of its transformation products. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2239–2243, 2002
Synthesis and investigation of oligosiloxanes containing γ‐trimethylsiloxy‐propyl or γ‐hydroxy‐propyl groups
Authors: Zhu Qingzeng , Feng Shengyu , Chen Jianhua 
Published: October 2002

AbstractOligosiloxanes having different distributions of SiH groups were prepared, and the addition of SiH bonds to CC double bounds of trimethyl(2‐propenyloxy)silane was utilized to obtain oligosiloxanes having different distributions of γ‐trimethylsiloxy‐propyl or γ‐hydroxy‐propyl groups as substituents. The oligosiloxanes were characterized by IR and 1H‐NMR spectroscopy. Viscosity was studied to investigate the effects of the substituents. Differential scanning calorimetry (DSC) was used to investigate the thermal behaviour of these oligosiloxanes. It was found that they are completely amorphous materials and, hence, show only a glass transition. We found that the viscosities and glass transition temperatures of these materials increased with the increasing of the number of substituents. Hydrogen bonds have a considerable influence on the increase of the viscosities and glass transition temperatures of oligosiloxanes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2431–2435, 2002
Controlled release of biocides in solid wood. II. Efficacy against Trametes versicolor and Gloeophyllum trabeum wood decay fungi
Authors: Liu Y. , Laks P. , Heiden P. 
Published: October 2002

AbstractBiocide‐containing nanoparticles were suspended in water to prepare wood treating suspensions able to deliver up to 0.8 kg biocide/m3 of wood. The nanoparticle preparation method was versatile, and three fungicides (tebuconazole, chlorothalonil, and KATHON 930) and one insecticide (chlorpyrifos) were incorporated into the nanoparticles with little customization of the preparative method. Greater customization was required when the polymer matrix was changed, but the method was generally robust; nanoparticles could be prepared from several different polymers, copolymers, and polymer blends. The median nanoparticle size increased as the matrix hydrophobicity increased. Nanoparticles were quantitatively delivered into birch and southern yellow pine (SYP) at low suspension loadings, but the delivery efficiency decreased with increased suspension loading and with increased matrix hydrophobicity. The delivery efficiency was also less for birch than for SYP. Undelivered nanoparticles were found to have undergone aggregation. Greater aggregation occurred in the more hydrophobic formulations than in the hydrophilic formulations. High biological efficacy was found for all the biocides tested. Nanoparticle‐treated birch was exposed to Trametes versicolor for 55 days and some protection was afforded, even at biocide loading levels of only 0.1 kg/m3. At the highest loadings (∼0.6 kg/m3) the weight loss after exposure to T. versicolor was generally ∼10% for most formulations. The SYP was treated with KATHON 930 in polyvinylpyridine. At levels of 0.1 kg of biocide/m3 of wood less than 5% of the SYP mass was lost after 50 days of exposure to Gloeophyllum trabeum. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 608–614, 2002
Diffusion behavior of hexane in diamine chain‐extended hydroxyterminated polybutadiene based polyurethanes
Authors: Gupta Tarakranjan , Adhikari Basudam 
Published: October 2002

AbstractA new method of edge correction has been formulated to calculate the near true diffusion coefficient of hexane in thin polyurethane and polyurethaneurea sheets. The method involves the calculation of time‐average thickness during the diffusion of hexane in hydroxyterminated polybutadiene‐based polyurethane and polyurethaneurea sheets. The precision of the method has been tested by the iteration of data. The diffusion coefficient increases with the increase of diamine chain extender in polyurethaneureas. The variation of activation parameters and enthalpy of diffusion of hexane with diamine chain extender in polyurethaneurea also have been studied. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 90–97, 2002
Characterization and properties of sPS/PET/SsPS‐K engineering plastic alloys
Authors: Wang Jin , Zhu Fangming , Li Huaming , Lin Shang'an 
Published: October 2002

AbstractThe compatibility, crystallization behavior, and mechanical properties of syndiotactic polystyrene (sPS)/polyester (PET)/potassium salt of sulfonated syndiotactic polystyrene (SsPS‐K) were investigated. DMA results showed that all the alloys showed one Tg and the half‐peak width of the sPS/PET/SsPS‐K alloys became narrower compared with that of sPS/PET alloys, which decreased with an increasing content of the SsPS‐K ionomer. The results of DSC showed that the Tm of sPS and PET of the alloys was similar to those of the pure materials and did not change with the content of the SsPS‐K ionomer, while the initial crystallization temperature (T0) and crystallization temperature at peak (Tp) increased. The crystallization velocity of PET increased with an increasing content of SsPS‐K. The TMA results showed that the alloys could retain the perfect heat proof property of sPS. SEM micrographs showed that the addition of SsPS‐K could reduce the PET domain dimension and enhance the adhesion between the PET domains and the matrix. With an increasing content of SsPS‐K, the PET domain dimension was reduced continuously and dispersed more evenly. The ternary alloys had better mechanical properties and significantly higher unnotched Izod impact strength than those of the alloys without SsPS‐K. When the weight ratio of sPS/PET/SsPS‐K was 85/15/4, the impact strength reached a maximum of 11.5 kJ/m2, which was about three times that of pure sPS, and still had a higher tensile strength, flexural strength, and storage modulus, which were 38.8, 54.2, and 1.55 × 104 MPa, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 656–661, 2002
Development of a poly(N‐vinyl‐2‐pyrrolidone)/poly (ethylene glycol) hydrogel membrane reinforced with methyl methacrylate‐grafted polypropylene fibers for possible use as wound dressing
Authors: Lopérgolo L. C. , Lugão A. B. , Catalaini L. H. 
Published: October 2002

AbstractA hydrogel is a polymeric material that exhibits the ability to swell in water and retains a significant fraction of water within its structure, but does not dissolve in water. One of the major problems in the application of these materials is their relatively poor mechanical strength, attributed to the high degree of hydration of the gel. This work was directed to the study of the interactions between hydrophobic and hydrophilized fibers, with the objective of optimization of the mechanical properties of poly(N‐vinyl‐2‐pyrrolidone) membranes. The membranes were prepared by electron‐beam irradiation of an aqueous polymer solution. A nonwoven cloth made of polypropylene matted fiber, grafted with methyl methacrylate, was employed as a reinforcement. The changes in the main properties of the membranes, such as the gel content, swelling characteristics, cytotoxicity, and mechanical behavior, were investigated. The results showed an increase of 800% in tensile strength, without changes in the swelling and cytotoxicity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 662–666, 2002
Synthesis and characterization of polyacrylamide‐grafted sodium alginate copolymeric membranes and their use in pervaporation separation of water and tetrahydrofuran mixtures
Authors: Kurkuri Mahaveer D. , Kumbar Sangamesh G. , Aminabhavi Tejraj M. 
Published: October 2002

AbstractPolyacrylamide‐grafted sodium alginate (PAAm‐g‐Na‐Alg) copolymeric membranes have been prepared, characterized, and used in the pervaporation separation of 10–80 mass % water‐containing tetrahydrofuran mixtures. Totally three membranes were prepared: (1) neat Na‐Alg with 10 mass % of polyethylene glycol (PEG) and 5 mass % of polyvinyl alcohol (PVA), (2) 46 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA, and (3) 93 % grafted PAAm‐g‐Na‐Alg membrane containing 10 mass % of PEG and 5 mass % of PVA. Using the transport data, important parameters like permeation flux, selectivity, pervaporation separation index, swelling index, and diffusion coefficient have been calculated at 30°C. Diffusion coefficients were also calculated from sorption gravimetric data of water–tetrahydrofuran mixtures using Fick's equation. Arrhenius activation parameters for the transport processes were calculated for 10 mass % of water in the feed mixture using flux and diffusion data obtained at 30, 35, and 40°C. The separation selectivity of the membranes ranged between 216 and 591. The highest permeation flux of 0.677 kg/m2 h was observed for 93% grafted membrane at 80 mass % of water in the feed mixture. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 272–281, 2002