bluuebunny/crossref_metadata_2025_split huggingface dataset:
Progressive loss of cardiac sympathetic innervation in Parkinson's disease
Authors: Li Sheng‐Ting , Dendi Raghuveer , Holmes Courtney , Goldstein David S. 
Published: October 2002

AbstractThis study addressed whether cardiac sympathetic denervation progresses over time in Parkinson's disease. In 9 patients without orthostatic hypotension, 6‐[18F]fluorodopamine positron emission tomography scanning was repeated after a mean of 2 years from the first scan. 6‐[18F]fluorodopamine‐derived radioactivity was less in the second scan than in the first scan, by 31% in the left ventricular free wall and 16% in the septum. In Parkinson's disease, loss of cardiac sympathetic denervation progresses in a pattern of loss suggesting a dying‐back mechanism.
Minocycline markedly protects the neonatal brain against hypoxic‐ischemic injury
Authors: Arvin Kara L. , Han Byung H. , Du Yansheng , Lin Sui‐Zhen , Paul Steven M. , Holtzman David M. 
Published: October 2002

AbstractHypoxic‐ischemic brain injury in the perinatal period is a major cause of morbidity and mortality. Presently, there are no proven effective therapies with which to safeguard the human neonatal brain against this type of injury. Minocycline, a semisynthetic tetracycline, has been shown to be neuroprotective in certain adult ischemic injury/stroke and neurodegenerative disease models. However, minocycline's neuroprotective effects have not been assessed after insults to the neonatal brain. We now report that minocycline administered either immediately before or immediately after a hypoxic‐ischemic insult substantially blocks tissue damage in a rodent model of neonatal hypoxic‐ischemic brain injury. Minocycline treatment prevents the formation of activated caspase‐3, a known effector of apoptosis, as well as the appearance of a calpain cleaved substrate, a marker of excitotoxic/necrotic cell death. To our knowledge, this is the first report of a systemic treatment that can be administered after a hypoxic‐ischemic insult, which provides robust, nearly complete neuroprotection to the developing brain. Our data suggest that minocycline or a related neuroprotective tetracycline may be a candidate to consider in human clinical trials to protect the developing brain against hypoxic‐ischemic–induced damage.
Gene transfer of HSP72 protects cornu ammonis 1 region of the hippocampus neurons from global ischemia: Influence of Bcl‐2
Authors: Kelly Stephen , Zhang Zhijian J. , Zhao Heng , Xu Lijun , Giffard Rona G. , Sapolsky Robert M. , Yenari Midori A. , Steinberg Gary K. 
Published: October 2002

AbstractWe investigated whether HSV gene transfer of HSP72 in vivo and in vitro: (1) protected cornu ammonis 1 region of the hippocampus neurons from global cerebral ischemia; and (2) affected Bcl‐2 expression. HSV vectors expressing HSP72 and β‐galactosidase (reporter) or β‐galactosidase only (control vector) were injected into cornu ammonis 1 region of the hippocampus 15 hours before induction of global cerebral ischemia (n = 10) and sham‐operated rats (n = 8). HSP72 vector–treated rats displayed significantly more surviving transfected neurons (X‐gal‐positive, 31 ± 8) compared with control vector–treated rats (10 ± 4) after global cerebral ischemia. Sham‐operated rats displayed similar numbers of X‐gal–positive neurons (HSP72 vector 18 ± 8 vs control vector 20 ± 7). The percentage of β‐galactosidase and Bcl‐2 coexpressing neurons in HSP72‐treated rats after global cerebral ischemia (84 ± 4%) was greater than that in control vector–treated rats (58 ± 9%). The percentage of β‐galactosidase and Bcl‐2 coexpressing neurons in sham‐operated rats was similar in HSP72 (93 ± 7%) and in control vector–treated rats (88 ± 12%). HSP72 vector transfection led to 12 times as much Bcl‐2 expression as the control vector in uninjured hippocampal neuronal cultures. In injured (oxygen‐glucose deprivation) hippocampal neuron cultures, HSP72 vector transfection led to 2.8 times as much Bcl‐2 expression as control vector. We show that HSP72 overexpression protects cornu ammonis 1 region of the hippocampus neurons from global cerebral ischemia, and that this protection may be mediated in part by increased Bcl‐2 expression.
Premotor cortex is involved in restoration of gait in stroke
Authors: Miyai Ichiro , Yagura Hajime , Oda Ichiro , Konishi Ikuo , Eda Hideo , Suzuki Tsunehiko , Kubota Kisou 
Published: October 2002

AbstractCortical activation during hemiplegic gait was assessed in six nonambulatory patients with severe stroke (four men, two women; four with right and two with left hemiplegia; 57 years old and 3 months after stroke on average), using a near‐infrared spectroscopic imaging system. Each patient performed tasks of treadmill walking (0.2km/hr), alternated with rest every 30 seconds for four repetitions, under partial body weight support, either with mechanical assistance in swinging the paretic leg control (CON) or with a facilitation technique that enhanced swinging of the paretic leg (FT), provided by physical therapists. Gait performance was associated with increased oxygenated hemoglobin levels in the medial primary sensorimotor cortex in the unaffected hemisphere greater than in the affected hemisphere. Both cortical mappings and quantitative data showed that the premotor activation in the affected hemisphere was enhanced during hemiplegic gait. There was also a prominent activation in the presupplementary motor area. Overall cortical activations and gait performance were greater in walking with FT than with CON. These indicate that multiple motor areas including the premotor cortex and presupplementary motor area might play important roles in restoration of gait in patients with severe stroke.
Silica reinforcement of synthetic diene rubbers by sol–gel process in the latex
Authors: Yoshikai Kazumasa , Ohsaki Tetsuro , Furukawa Mutsuhisa 
Published: October 2002

AbstractStyrene–butadiene rubber (SBR) and nitrile rubber (NBR) were reinforced with silica by the sol–gel method of tetraethoxysilane (TEOS) in latex. The sol–gel reaction proceeded in the mixture of latex, TEOS, water, and a catalyst. The compound that involved silica was crosslinked with the curing agent at 150°C. The amount of TEOS added and the molar ratio of TEOS to water ([H2O]/[TEOS]) in the mixture were related to the silica content in the compounds, particle size, and reinforcing behavior of silica. The particle size and reinforcing behavior of the silica were greatly influenced by the amount of TEOS and [H2O]/[TEOS]. The diameter of the dispersed silica particles in cured rubbers was controlled by the amount of TEOS and [H2O]/[TEOS], which were smaller than 100 nm. By the dispersion of the fine silica in the nanometer‐order level, the tensile strength of the compound was drastically improved. The tensile strength of SBR was over 30 MPa, and of NBR, over 25 MPa. Compounds with a high tensile strength had a high bound rubber fraction and a very strong interaction of the fine silica with rubber. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2053–2063, 2002
Infrared spectroscopy and electrical properties of ternary poly(acrylic acid)–metal–poly(acrylamide) complexes
Authors: Moharram M. A. , El‐Gendy H. M. 
Published: October 2002

AbstractFourier transform infrared spectroscopy (FTIR) and electrical measurements were used for the characterization of the interpolymer complexation between poly(acrylic acid) (PAA) and poly(acrylamide) (PAAm) and also the ternary PAA–metal–PAAm complexes. The interpolymer complexes were prepared by adjusting the pH value of the mixture solutions at different PAA weight fractions (WPAA). The ternary complexes were prepared by mixing metal chloride solutions (such as ErCl3 and LaCl3) with different concentrations to PAA–PAAm mixtures and adjusting the pH value for different WPAA. It was found that the IR spectra of the interpolymer complexes showed absorption bands at shifted positions and of intensities different from those of the parent polymers. Also, the examination of the spectra of the ternary metal–polymer complexes revealed that they depend on the nature,
lency, ionic radius, and concentration of the added metal chlorides. Analysis of the electrical results showed that the electrical conductivity of the interpolymer complexes are always lower than those of PAA and PAAm, which was attributed to the decrease in the mobility of the polymer chains as a result of the complexation. Also, the conductivity of the ternary metal complexes showed a dependence on the properties of the additives and were found to decrease with increasing their concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2699–2705, 2002
Blends of natural rubber latex and methyl methacrylate‐grafted rubber latex
Authors: Lu Guang , Li Zhi‐Feng , Li Si‐Dong , Xie Jian 
Published: October 2002

AbstractBy mixing natural rubber latex uniformly with methyl methacrylate‐grafted natural rubber latex and then carrying out prevulcanization, we obtained blends with stable viscosities. Under certain blending ratios, the blends maintained good basic properties, and the heat stability time (THS) of the blend increased with the increment of percent content of MG49 latex (C). The relationship between THS and C was THS = 0.36C + 33.0, whereas, the mechanical stability time (TMS) was slightly decreased, and the relationship between TMS and C was TMS = −1.33C + 772.0; The modulus, antiaging properties, and tear strength of the films of the blends increased with the increment of C; the tensile strengths fluctuated on a small scope; the Shore A hardness (H) and breaking set (BS) both increased with the increment of C; their relationships were H = 0.66C + 40.0 and BS = 0.46C + 8.0, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1736–1741, 2002
Synthesis of polyaluminocarbosilane and reaction mechanism study
Authors: Cao Feng , Kim Dong‐Pyo , Li Xiao‐Dong , Feng Chun‐Xiang , Song Yong‐Cai 
Published: October 2002

AbstractPolyaluminocarbosilane (PACS) as the precursor of high‐temperature resistant SiC fibers was synthesized by reacting polycarbosilane (PCS) with aluminum(III)acetylacetonate [Al(AcAc)3] at 310°C in N2 under ambient pressure. The reaction mechanism and the structure of PACS were investigated in detail by FTIR, GPC, GC/MS, ESCA, and elemental analysis. The reaction was proven complex involving the formation of SiOAl and SiAlSi bonds, which were accompanied by the evolution of 3‐methoxy‐2,2‐dimethyl‐oxirane, 2,3‐dihydro‐[1,4]dioxine, pent‐3‐en‐2‐one, and 3‐ethyl‐but‐3‐en‐2‐one, and acetylacetone. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2787–2792, 2002
Study of the preparation and mechanism of formation of hollow monodisperse polystyrene microspheres by SPG (Shirasu Porous Glass) emulsification technique
Authors: Ma Guang‐Hui , Omi Shinzo , Dimonie Victoria L. , Sudol E. David , El‐Aasser Mohamed S. 
Published: October 2002

AbstractIn a previous study, it was found that monodisperse polystyrene (PSt) hollow particles can be prepared under special conditions by combining a Shirasu Porous Glass (SPG) emulsification technique and subsequent suspension polymerization process. That is, a mixture of styrene (St), N,N‐dimethylamino ethyl methacrylate (DMAEMA), hexadecane (HD), and initiator N, N′‐azobis(2,4‐dimethylvaleronitrile) (ADVN) was used as the dispersed phase in an aqueous phase containing poly(vinyl pyrrolidone) (PVP), sodium lauryl sulfate (SLS), and water‐soluble inhibitor. The dispersed phase was created by pushing the oil phase through the uniform pores of an SPG membrane into the continuous phase to form uniform droplets. Then, the droplets were polymerized at 70°C. It has been puzzling that hollow microspheres were obtained only when sodium nitrite (NaNO2) was used as a water‐soluble inhibitor, while one‐hole particles were formed when hydroquinone (HQ) or diaminophenylene (DAP) was used. In this study, the mechanism of formation of the hollow microspheres was verified by measuring the variation of diameter, molecular weight distribution, and monomer conversion, and by observing morphological changes during the polymerization, as well as by changing the type and amount of hydrophilic monomer, and initiator. It was found that the diameter of the oil droplets decreased, and a large amount of secondary new particles formed immediately after polymerization started in the case of NaNO2. However, there was no such apparent behavior to be observed when HQ or DAP was used. It was determined that the hollow particles formed due to the rapid phase separation between PSt and HD, and as a consequence, a large amount of monomer diffused into the aqueous phase to form the secondary particles. Rapid phase separation confined the HD inside the droplets, a nonequilibrium morphology. On the other hand, one‐hole particles, representing an equilibrium morphology, formed when the phase separation occurred slowly because a lot of monomer existed inside of the droplets to allow mobility of the PSt. The addition of DMAEMA allowed the hollow particles to be formed more easily by decreasing the interfacial tension between the copolymer and aqueous phase. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1530–1543, 2002
Bioerodible hydrogels based on 2‐hydroxyethyl methacrylate: Synthesis and characterization
Authors: Chiellini Federica , Petrucci Federica , Ranucci Elisabetta , Solaro Roberto 
Published: October 2002

AbstractBiocompatible polymers with specific shape and tailored hydrogel properties were obtained by polymerization of mixtures of 2‐hydroxyethyl methacrylate (HEMA) with 1–8 wt % ethylene glycol dimethacrylate (EGDMA) or tetra(ethylene glycol) diacrylate (TEGDA) as crosslinking agents, by using a redox initiator. Introduction of charged positive and negative groups was easily achieved by direct polymerization of appropriate monomer mixtures and by chemical transformation of preformed hydrogels. Investigation of the swelling behavior of the prepared hydrogels evidenced an appreciable dependence on both solvent type and polymer chemical structure. Additionally, the solvation process resulted in being controlled by solvent diffusion, according to a Fickian II mechanism. The presence of several types of water with different melting behavior was observed in fully swollen hydrogels. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2729–2741, 2002
Distribution coefficients and diffusivities in three polymers for nineteen aqueous nonvolatile solutes
Authors: Fornasiero F. , Olaya M. M. , Esprester B. , Nguyen V. , Prausnitz J. M. 
Published: October 2002

AbstractExperimental results at 25°C are reported for infinite‐dilution distribution coefficients for 19 nonvolatile solutes between aqueous solution and three kinds of polymer films, and for their diffusion coefficients in the polymer matrix. The experiments were performed by coupling UV spectroscopy and gravimetric measurements with mass balances. The solutes are aromatic nonvolatile compounds that are of interest in environmental technology and may serve as model compounds for drug‐delivery systems. The polymers are ethylene‐vinyl acetate copolymers with 33 (EVAc33) and 45 (EVAc45) weight percentage vinyl acetate, and poly(vinyl acetate) (PVAc) widely used in drug‐delivery devices. For PVAc, a long time is required to reach equilibrium. Because the required time is too long for reasonable experimental studies, equilibrium distribution coefficients were calculated from finite‐time data by using a diffusion model. The contribution of surface adsorption is shown to be negligible. Infinite‐dilution distribution coefficients Ks, defined as the volume fraction of solute in the polymer divided by that in water, tend to increase with vinyl acetate content; they range from near unity to several hundred. Diffusion coefficients, determined from time‐dependent sorption data, are significantly larger in EVAc copolymers (10−10 to 10−8 cm2/s) than in PVAc (10−12 cm2/s). These data may be useful for design of membrane processes, for controlled delivery of drugs, and for application in packaging and storage of food, chemicals, and pharmaceuticals. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2041–2052, 2002
Study on the effect of acid‐ or iodine‐doping on the properties of copolymer C1–4poly‐phenylene‐vinylene‐ether
Authors: Alimi K. , Ayachi S. , Mabrouk A. , Molinie P. , Zaidi B. , Bernede J. C. , Ghedira M. 
Published: October 2002

AbstractIn this article, the new red‐colored copolymer, referred to as C1–4poly‐phenylene‐vinylene‐ ether (C1–4PPV‐ether) is built as a PPV polymer with some conjugated links (CHCH) that are changed into ethylic‐ether links ( CH2OCH2) and whose modified phenyl ring is grafted, respectively, in two and five positions with methoxy and butoxy groups. The C1– 4PPV‐ether is doped with protonic acid or iodine. The infrared absorption (IR), optical density, X‐ray photoelectron spectroscopy (XPS), and electron spin resonance (ESR) show that there is a charge transfer complex formed between the copolymer and the doping species (iodine or acidic dopants). From IR, XPS, and ESR analysis, we deduced that the doping mechanism of the copolymer is, respectively, a protonation of the double links in PPV in the case of the protonic acid doping process and a grafting of the iodine to the ether links in the case of iodine‐doping process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1858–1866, 2002
Influences of trans‐polyoctylene rubber on the physical properties and phase morphology of natural rubber/acrylonitrile–butadiene rubber blends
Authors: Nah Changwoon , Han Seung‐Cheol , Jo Byung Wook , Kim Wan Doo , Chang Young‐Wook 
Published: October 2002

AbstractThe influence of trans‐polyoctylene rubber (TOR) on the mechanical properties, glass‐transition behavior, and phase morphology of natural rubber (NR)/acrylonitrile–butadiene rubber (NBR) blends was investigated. With an increased TOR level, hardness, tensile modulus, and resilience increased, whereas tensile strength and elongation at break tremendously decreased. According to differential scanning calorimetry and dynamic mechanical analysis, there were two distinct glass‐transition temperatures for a 50/50 NR/NBR blend, indicating the strongly incompatible nature of the blend. When the TOR level was increased, the glass transition of NBR was strongly suppressed. NBR droplets of a few micrometers were uniformly dispersed in the continuous NR phases in the NR/NBR blends. When TOR was added to a 50/50 NR/NBR blend, TOR tended to be located in the NR phase and in some cases was positioned at the interfaces between the NBR and NR phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 125–134, 2002
Properties of bioriented nylon 6 films related to film production technology
Authors: Bianchi F. , Cantagallo S. , Consolati G. , Laporta M. , Pegoraro M. , Tieghi G. , Zanderighi L. 
Published: October 2002

AbstractFour production steps, extrusion, blowing, stabilization, and finishing, are involved in the manufacture of biorented nylon 6 films. The films obtained after each step were studied by wide‐angle diffraction X‐rays, IR analysis, and density measurements. Orientation in the amorphous phase was evaluated by thermal retraction. Free volume was investigated by positron annihilation spectroscopy. Mechanical properties were tested by tensile tests, and permeability was tested with isopiestic permeameters. Quenching, after extrusion, generated an unstable γ crystalline phase and an amorphous phase. Blowing transformed the unstable γ phase into the thermodynamically stable α phase and increased the chain orientation; stabilization increased α phase crystals, favored hydrogen bond formation and, therefore, the mechanical properties, leaving unchanged the chain orientation; the final treatment increased the mechanical properties. The film permeabilities to O2, N2, and CO2 were practically unchanged after each production step; this result may be explained by considering that the nanoholes, present in the films and responsible for the diffusion inside the polymer, maintained practically constant their radius, whereas their number concentration decreased slowly after thermomechanical treatments. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 559–571, 2002
Recycling of acrylonitrile–butadiene–styrene and high‐impact polystyrene from waste computer equipment
Authors: Brennan L. B. , Isaac D. H. , Arnold J. C. 
Published: October 2002

AbstractAcrylonitrile–butadiene–styrene (ABS) and high‐impact polystyrene (HIPS) are two of the plastics most frequently used as outer casings for computer equipment such as monitors, keyboards, and other similar components. We assessed the effects of the recycling and blending of ABS and HIPS on mechanical properties. We found that the effects of recycling on ABS and HIPS were similar, in that changes in glass‐transition temperatures, tensile strengths, and tensile moduli were negligible, but strains to failure and impact strengths were reduced considerably. Blending proportions of ABS and HIPS caused no more deterioration in properties than occurred as a result of the recycling process, and the presence of small proportions of one material in the other actually restored significant amounts of ductility, as seen by increases in the strains to failure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 572–578, 2002
Oligolactate‐grafted dextran hydrogels: Detection of stereocomplex crosslinks by X‐ray diffraction
Authors: de Jong S. J. , van Nostrum C. F. , Kroon‐Batenburg L. M. J. , Kettenes‐van den Bosch J. J. , Hennink W. E. 
Published: October 2002

AbstractPhysically crosslinked hydrogels are formed upon mixing equal amounts of aqueous solutions of dextran grafted with L‐lactic acid oligomers and dextran grafted with D‐lactic acid oligomers. In this paper, the dex‐lactate hydrogels are analyzed by X‐ray diffraction to provide evidence that hydrogel formation occurred through stereocomplex formation. First, the stereocomplex formation of monodisperse lactic acid oligomers was studied and comparison with published results of poly(lactic acid) was made. It was clearly demonstrated that stereocomplexes were formed between oligomers of opposite chirality. The data for these monodisperse lactic acid oligomers were used to interpret the results obtained with the dex‐lactate hydrogels. X‐ray diffraction measurements demonstrated that in the hydrogels stereocomplexes were formed between the lactic acid oligomers of opposite chirality. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 289–293, 2002
Synthesis and photopolymerization of acrylic acrylate copolymers
Authors: Valette Ludovic , Massardier Valérie , Pascault Jean‐Pierre , Magny Benoit 
Published: October 2002

AbstractAcrylate‐functionalized copolymers were synthesized by the modification of poly(butyl acrylate‐co‐glycidyl methacrylate) (BA/GMA) and poly(butyl acrylate‐co‐methyl methacrylate‐co‐glycidyl methacrylate). 13C‐NMR analyses showed that no glycidyl methacrylate block longer than three monomer units was formed in the BA/GMA copolymer if the glycidyl methacrylate concentration was kept below 20 mol %. We chemically modified the copolymers by reacting the epoxy group with acrylic acid to yield polymers with various glass‐transition temperatures and functionalities. We studied the crosslinking reactions of these copolymers by differential scanning calorimetry to point out the effect of chain functionality on double‐bond reactivity. Films formed from acrylic acrylate copolymer precursors were finally cured under ultraviolet radiation. Network heterogeneities such as pendant chains and highly crosslinked microgel‐like regions greatly influenced the network structure and, therefore, its viscoelastic properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 753–763, 2002