bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron‐Beam Irradiation in TEM of Hard‐Segment Homopolymers and Polyurethanes with Different Hard‐Segment Content
Authors: Janik Helena 
Published: June 2004

AbstractSummary: A hard‐segment homopolymer (HSH) and segmented poly(ester urethanes) (PESU) were studied by TEM to estimate their stability against electron‐beam irradiation. The bright‐field image and electron‐diffraction modes in TEM and optical polarised microscopy were used. It is shown that both soft and hard segments are sensitive to the electron beam. None of the films was stable enough to register an electron‐diffraction pattern without damage.Electron‐diffraction pattern taken from the film of hard‐segment homopolymer crystallised at 100 °C from DMF: (a) the pattern registered immediately; (b) the pattern registered after 5 s of exposure in the TEM at the same place.imageElectron‐diffraction pattern taken from the film of hard‐segment homopolymer crystallised at 100 °C from DMF: (a) the pattern registered immediately; (b) the pattern registered after 5 s of exposure in the TEM at the same place.
Photo‐Rheometry/NIR Spectrometry: An in situ Technique for Monitoring Conversion and Viscoelastic Properties during Photopolymerization
Authors: Botella Aurélie , Dupuy Jérôme , Roche Alain‐André , Sautereau Henry , Verney Vincent 
Published: June 2004

AbstractSummary: A suitable rheometer for simultaneous dynamic mechanical analysis (DMA) and NIR (Near Infra‐Red) in situ analysis during UV curing was developed. The conversion and viscoelastic properties of a dimethacrylate/styrene‐based system were investigated. The results were plotted against both irradiation time and total average conversion. For the same conversion, a lower intensity delays the reaction but does not affect the viscoelastic properties.A device for simultaneous photo‐rheology and NIR spectroscopy experiments.imageA device for simultaneous photo‐rheology and NIR spectroscopy experiments.
Complex Formation between Polyisoprene and Cyclodextrins
Authors: Michishita Takeshi , Takashima Yoshinori , Harada Akira 
Published: June 2004

AbstractSummary: Polyisoprenes were found to form inclusion complexes with cyclodextrins with high selectivity to give crystalline compounds. β‐Cyclodextrin formed complexes only with polyisoprene of low molecular weight, whereas γ‐cyclodextrin formed complexes with polyisoprenes of high molecular weight. α‐Cyclodextrin did not form complexes with polyisoprene of any molecular weight. The yields of γ‐cyclodextrin complexes increased with increasing molecular weights of the polyisoprenes and reached a maximum of around several thousands, and then decreased.Theoretical depiction of the complex formed between polyisoprene and γ‐CD, as determined by molecular modelling studies. The PIP chain is shown penetrating the γ‐CD cavity, which, in turn, accommodates one to 1.5 monomer units of PIP.imageTheoretical depiction of the complex formed between polyisoprene and γ‐CD, as determined by molecular modelling studies. The PIP chain is shown penetrating the γ‐CD cavity, which, in turn, accommodates one to 1.5 monomer units of PIP.
Synthesis and Characterization of Star‐Shaped Diblock Poly(ε‐caprolactone)/Poly(ethylene oxide) Copolymers
Authors: Maglio Giovanni , Nese Giuseppe , Nuzzo Margherita , Palumbo Rosario 
Published: June 2004

AbstractSummary: Star‐shaped hydroxy‐terminated poly(ε‐caprolactone)s (ssPCL), with arms of different lengths, were obtained by ring‐opening polymerization (ROP) of ε‐caprolactone initiated by pentaerythritol, and were condensed with α‐methyl‐ω‐(3‐carboxypropionyloxy)‐poly(ethylene oxide)s ($\overline M _{\rm n}$ = 550–5 000) to afford four‐armed PCL‐PEO star diblock copolymers (ssPCL‐PEO). The polymers were characterized by 1H and 13C NMR spectroscopy and size‐exclusion chromatography (SEC). The melting behavior of ssPCLs was studied by differential scanning calorimetry (DSC). X‐ray diffraction and DSC techniques were used to investigate the crystalline phases of ssPCL‐PEOs.The part of the synthesis of four‐armed star‐shaped diblock poly(ε‐caprolactone)‐poly(ethylene oxide) copolymers as described.imageThe part of the synthesis of four‐armed star‐shaped diblock poly(ε‐caprolactone)‐poly(ethylene oxide) copolymers as described.
CASK and Dlg form a PDZ protein complex at the mammalian neuromuscular junction
Authors: Sanford Jamie L. , Mays Tessily A. , Rafael‐Fortney Jill A. 
Published: June 2004

AbstractMembrane‐associated guanylate kinases (MAGUKs) are modular adapter proteins that serve as scaffolding molecules and anchor channels and receptors via their PDZ (PSD‐95, Dlg, Zo‐1) domains. Calcium, calmodulin‐associated serine/threonine kinase (CASK) is a MAGUK that is critical at synapses in the central nervous system and at cell–cell junctions because of its interactions with channels, receptors, and structural proteins. We show via confocal microscopy that CASK and another MAGUK, Discs Large (Dlg), are present at the mammalian neuromuscular junction in skeletal muscle. Immunoprecipitation data from mouse muscle show that CASK associates with Dlg, providing evidence of a MAGUK protein complex at this synapse. These data indicate that CASK and Dlg may act as a scaffold for organizing receptors and channels at the postsynaptic membrane of the neuromuscular junction. Muscle Nerve 30: 164–171, 2004
Target‐derived and locally derived neurotrophins support retinal ganglion cell survival in the neonatal rat retina
Authors: Spalding Kirsty L. , Rush Robert A. , Harvey Alan R. 
Published: June 2004

AbstractBrain‐derived neurotrophic factor (BDNF) and neurotrophin‐4/5 (NT‐4/5) protein and mRNA are found in the neonatal rat retina and also in target sites such as the superficial layers of the superior colliculus. Both neurotrophins support neonatal retinal ganglion cell survival in vitro. In vivo, injections of recombinant BDNF and NT‐4/5 reduce naturally occurring cell death as well as death induced by removal of the contralateral superior colliculus. In the latter case, the peak of retinal ganglion cell death occurs about 24 h postlesion. We wished to determine: whether a similar time‐course of degeneration occurs after selective removal of target cells or depletion of target‐derived trophic factors, and whether ganglion cell viability also depends on intraretinally derived neurotrophins. Retinal ganglion cell death was measured 24 and 48 h following injections of kainic acid or a mixture of BDNF and NT‐4/5 blocking antibodies into the superior colliculus and 24 h after intraocular injection of the same antibodies. Retinotectally projecting ganglion cells were identified by retrograde labeling with the nucleophilic dye diamidino yellow. We show that collicular injections of either kainic acid or BDNF and NT‐4/5 blocking antibodies significantly increased retinal ganglion cell death in the neonatal rat 24 h postinjection, death rates returning to normal by 48 h. This increase in death was greatest following collicular injections; however, death was also significantly increased 24 h following intravitreal antibody injection. Thus retinal ganglion cell survival during postnatal development is not only dependent upon trophic factors produced by central targets but may also be influenced by local intraretinal neurotrophin release. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 319–327, 2004
Crystallization and melting behaviour of polypropylene/barium sulfate composites
Authors: Wang Ke , Wu Jingshen , Zeng Han‐Min 
Published: June 2004

AbstractThe effects of polypropylene (PP)–barium sulfate (BaSO4) interfacial interaction on the crystallization and melting behaviour of PP/BaSO4 composites were investigated by means of differential scanning calorimetry. The results show that BaSO4 can act as nucleating agent and the nucleation activity increases when the PP–BaSO4 interface is modified. Neat PP exhibits a single fusion endotherm after being non‐isothermally crystallized, whereas the PP/BaSO4 composites show dual endotherms or a broad endotherm with a shoulder at the low temperature side, indicating that there are more crystallites with less perfection formed in the composite samples. It is shown that the hindrance of BaSO4 particles on the transport of PP chains to the crystallization zone is responsible for the formation of the less perfect crystallites. Moreover, the melting patterns of the composites are different from sample to sample, which can be attributed to the different extents of deviation from equilibrium at which the crystallization processes proceeded. Copyright © 2004 Society of Chemical Industry
Cationic electron‐beam curing of a high‐functionality epoxy: effect of post‐curing on glass transition and conversion
Authors: Rath SK , Boey FYC , Abadie MJM 
Published: June 2004

AbstractThis paper reports on the cationic electron‐beam curing of a high‐functionality SU8 epoxy resin, which is extensively used as a UV‐curing negative photoresist for micro‐electronics machine systems (MEMS) applications. Results show that elevated post‐curing treatment significantly increased both the conversion and the glass transition. The degree of conversion and the glass transition temperature were measured by using Fourier‐transform infrared (FTIR) spectroscopy and modulated differential scanning calorimetry (MDSC®), respectively. The glass transition temperature (Tg), which has been observed to be dependent on the degree of conversion, reaches a maximum of 162 °C at 50 Mrad and post‐curing at 90 °C. The degradation pattern of the cured resin does not show much variation for exposure at 5 Mrad, but does show significant variation for 50 Mrad exposure at various post‐curing temperatures. A degree of conversion of more than 0.8 was achieved at a dosage of 30 Mrad with post curing at 80 °C, for the epoxy resin with an average functionality of 8 a feature simply not achievable when using UV‐curing. Copyright © 2004 Society of Chemical Industry
Space‐charge limited conduction in polyaniline films
Authors: Nazeer K Prem , Jacob Sheeba Anu , Thamilselvan M , Mangalaraj D , Narayandass Sa K , Yi Junsin 
Published: June 2004

AbstractPolyaniline emeraldine base (PANI‐EB) powder was synthesized by oxidative polymerization of aniline. The PANI‐EB films were prepared by the solution‐casting technique. The temperature‐dependent dc conductivity measured in the range 173–303 K suggests that the PANI‐EB is a quasi‐one‐dimensional disordered conductor. The current‐voltage characteristics of the PANI‐EB films measured in the range 333–383 K showed the SCLC mechanism. The SCLC parameters such as free carrier density (p0), trap density (pt), the ratio between free carrier density to the total carrier density (θ), mobility (µ) and the effective hole mobility (µeff) were calculated. The activation energy (Ea = 0.32 eV) and the Fermi level (EF = 0.42 eV) were estimated. As well as these, the trap parameters such as the trap filled limit voltage (VTFL), the shallow trap density (Nt), the depth of the dominant trap level (Et − Ev), the density of states within the hole mobility edge (Nv) and the characteristic energy (Ec) were also calculated and presented. The exponential type of traps distribution with large number of traps was found to be due to the disorder and moisture in the polymer films. Copyright © 2004 Society of Chemical Industry
Comparative study of PHBV/TBP and PHBV/BPA blends
Authors: Fei Bin , Chen Cheng , Wu Hang , Peng Shuwen , Wang Xiuyan , Dong Lisong 
Published: June 2004

AbstractIn order to clarify the effects of phenols on properties of polyesters, the blends of poly[(3‐hydroxybutyrate)‐co‐(3‐hydroxyvalerate)] (PHBV) with 4,4′‐dihydroxydiphenylpropane (BPA) and p‐tert‐butylphenol (TBP) were studied. The FTIR spectra revealed that there was strong hydrogen‐bond (H‐bond) interaction between PHBV and both phenols. By evaluating the fraction of H‐bonded CO in the blend, it was concluded that BPA showed a stronger tendency than TBP to form H‐bonds with PHBV. Accordingly, BPA formed a stronger suppression than TBP on the crystallization of PHBV. When 30 wt% BPA or 50 wt% TBP were added into PHBV, the crystallization of PHBV was completely suppressed in the DSC cooling scan. As the phenol content was increased, the Tg of PHBV/TBP blend decreased while the Tg of PHBV/BPA blend increased. This difference indicated that TBP and BPA acted as plasticizer and physical crosslinking agent, respectively. Copyright © 2004 Society of Chemical Industry
Heterogeneous blends of recycled poly(ethylene terephthalate) with impact modifiers: phase structure and tensile creep
Authors: Pegoretti Alessandro , Kolarík Jan , Gottardi Gianluca , Penati Amabile 
Published: June 2004

AbstractSeveral types of photomicrographs have concurrently shown that impact modifiers (IMs) form particles (on a micrometre scale) which are evenly dispersed in a recycled poly(ethylene terephthalate) (PET) matrix; their adhesion to the latter is high enough that fracture surfaces (produced in liquid nitrogen) do not follow the interface. An essential part of the tensile creep of PET corresponds to the elastic time‐independent component; the time‐dependent component is rather limited, even if relatively high stresses are applied. Thus, the tensile compliance of PET is virtually independent of the applied stress, which indicates linear viscoelastic behaviour. The compliance of PET/IM blends (93/7, 90/10, 85/15 (by weight)) grows with the IM content and its time‐dependence becomes more visible. The effects of the two types of IM used in this study seem to be practically identical from the viewpoint of dimensional stability of the blends. The logarithm of compliance grows with the logarithm of time faster than linearly, and this tendency becomes more apparent with increasing fraction of IM. Even if the strain‐induced free volume is taken into account, a noticeable upswing of the compliance for longer creep periods (t > 1000 min) is evident. This cannot be interpreted as a consequence of the flow, because the recovery following the creep has proved the complete reversibility of the previous deformation. A simple empirical equation is proposed, which provides a plausible prediction of the creep behaviour of PET with dispersed impact modifiers. Copyright © 2004 Society of Chemical Industry
Rapid living free‐radical polymerization of methyl acrylate under 60Co γ‐ray irradiation at room temperature
Authors: Hua Daoben , Cheng Kun , Bai Ruke , Lu Weiqi , Pan Caiyuan 
Published: June 2004

AbstractRapid living free‐radical polymerization of methyl acrylate under 60Co γ‐ray irradiation in the presence of benzyl 1H‐imidazole‐1‐carbodithioate at room temperature is reported. The results showed that the polymerization is a fast living process, and that the molecular weight of the polymer is as high as 39 600 g mol−1 at 68 % conversion with Mw/Mn = 1.09 within 68 min. The polymerization rate was markedly influenced by the structures of thiocarbonylthio compounds. Copyright © 2004 Society of Chemical Industry
New antigenic candidates in multiple sclerosis: Identification by serological proteome analysis
Authors: Almeras Lionel , Lefranc Didier , Drobecq Hervé , de Seze Jérome , Dubucquoi Sylvain , Vermersch Patrick , Prin Lionel 
Published: June 2004

AbstractMyelin antigen targets that are clearly associated with pathogenic events in multiple sclerosis (M.S.) patients remain to be defined. We recently demonstrated that the analysis of global IgG antibody response against human brain antigens using one‐dimensional (1‐D) immunoblotting, allowed us to discriminate M.S. patients from controls (both healthy subjects and patients with Sjögren's syndrome). Additionally, this approach also differentiated the three clinical forms of M.S. Indeed, 42 brain antigenic bands (26 from healthy brain and 16 from the M.S. brain) showed the discriminant IgG immune responses. The aim of our study was to characterize the 26 discriminant antigenic bands detected in healthy brain. Protein identification was successively performed by 1‐D and two‐dimensional (2‐D) immunoblottings using sera from 18 M.S. patients, followed by mass spectrometry (MS) analysis and a database search. One hundred and two antigenic spots were then detected on 2‐D immunoblots, with M.S. sera against healthy brains. Sixty‐four spots were successfully matched with 2‐D Coomassie brillant blue stained gels, which were further selected for MS analysis and annotated leading to the identification of 14 of the 26 discriminant antigens. Thus, serological proteome analysis may provide a useful tool for the identification of potentially new M.S.‐associated antigens, whose relevance to physiopathological events remains to be defined.
Synthesis of azobenzene‐containing polythiophenes and photoinduced anisotropy
Authors: Aubertin Francois , Zhao Yue 
Published: June 2004

AbstractThree new polythiophenes containing an azobenzene moiety in the side‐chain were synthesized and characterized. Two of them, which are slightly soluble in tetrahydrofuran to allow the preparation of thin films from solution casting, were used to investigate the photoinduced anisotropy arising from the photoisomerization of azobenzene in this type of polymer. The results show that, unlike other amorphous azobenzene polymers, only an extremely small anisotropy can be induced on excitation with an Ar+ laser at 488 nm in these azobenzene‐containing polythiophenes, and that this photoinduced anisotropy is observable only by heating the polymer to some temperatures below glass transition temperature. It is suggested that the inability for azobenzene polythiophenes to display a significant photoinduced anisotropy may be caused by some structural constraints and/or a severe interference from conjugated thiophene chains that absorb strongly in the visible region. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3445–3455, 2004
Synthesis, characterization, and emulsion polymerization of polymerizable coumarin derivatives
Authors: Oh Jung Kwon , Stöeva Valentina , Rademacher Jude , Farwaha Rajeev , Winnik Mitchell A. 
Published: June 2004

AbstractWe describe the synthesis of a new polymerizable coumarin derivative, [6‐(β‐acryloxyethoxy)‐7‐isopropoxy‐4‐methyl coumarin (3)], whose UV absorption spectrum significantly overlaps the emission spectrum of 9‐alkyl phenanthrene chromophore. This dye can serve several purposes in latex films. It can be a tracer for fluorescence microscopy experiments, or it can act as a donor or acceptor dye in nonradiative energy transfer experiments. Here we emphasize its role as an energy transfer acceptor in experiments with phenanthrene as the corresponding donor. Coumarin‐labeled poly(butyl methacrylate) latex dispersions could be synthesized by conventional batch emulsion polymerization with complete monomer conversion, complete dye incorporation, and uniform dye distribution. Attempts to extend this reaction to poly(vinyl acetate) copolymers failed because the dye inhibited monomer conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3479–3489, 2004
Preparation and thermomechanical properties of epoxy resins modified by octafunctional cubic silsesquioxane epoxides
Authors: Mya Khine Yi , He Chaobin , Huang Junchao , Xiao Yang , Dai Jie , Siow Yeen‐Ping 
Published: June 2004

AbstractThe thermomechanical properties of octafunctional cubic silsesquioxane‐modified epoxy resins associated with dicycloaliphatic hardener (4,4′‐dimethyldiaminodicyclo hexyl methane) were studied using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The structures of epoxy resin containing cubic silsesquioxane epoxides were characterized by Fourier transform infrared spectroscopy and wide‐angle X‐ray scattering techniques. In this work, octa(dimethylsiloxybutylepoxide) octasilsesquioxane (OB), and octa(glycidyldimethyl‐siloxyepoxide) octasilsesquioxane (OG), were synthesized and used as additives to improve the properties of a commercial epoxy resin by exploring the effects of varying the ratio of OB or OG. The commercial Ciba epoxy resin (Araldite LY5210/HY2954) was used as a standard. It was found, by thermogravimetric analysis and dynamic mechanical analysis, that the highest thermal stability was observed atN= 0.5 (N= number of amine groups/number of epoxy rings). No glass transition temperature was observed by adding 20 mol % OB to the Ciba epoxy resin, indicating the reduction of chain motion in the presence of octafunctional cubic silsesquioxane epoxide. The storage modulus of the OB‐modified epoxy resin also increased, especially at higher temperatures, compared with the Ciba epoxy resin under identical curing conditions. Fourier transform infrared data elucidated the preservation of cubic silsesquioxane structure after curing at high temperature. In contrast, the OG/Araldite LY5210/HY2954 systems gave poorer thermomechanical properties. The low viscosity of OB at room temperature (∼ 350 cPs) makes it suitable for composite processing and, when used in conjunction with the Ciba epoxy, lowers the viscosity of this system as well. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3490–3503, 2004
Physicochemical characterization of α‐chitin, β‐chitin, and γ‐chitin separated from natural resources
Authors: Jang Mi‐Kyeong , Kong Byeong‐Gi , Jeong Young‐Il , Lee Chang Hyung , Nah Jae‐Woon 
Published: June 2004

AbstractWe isolated α‐chitin, β‐chitin, and γ‐chitin from natural resources by a chemical method to investigate the crystalline structure of chitin. Its characteristics were identified with Fourier transform infrared (FTIR) and solid‐state cross‐polarization/magic‐angle‐spinning (CP–MAS) 13C NMR spectrophotometers. The average molecular weights of α‐chitin, β‐chitin, and γ‐chitin, calculated with the relative viscosity, were about 701, 612, and 524 kDa, respectively. In the FTIR spectra, α‐chitin, β‐chitin, and γ‐chitin showed a doublet, a singlet, and a semidoublet at the amide I band, respectively. The solid‐state CP–MAS 13C NMR spectra revealed that α‐chitin was sharply resolved around 73 and 75 ppm and that β‐chitin had a singlet around 74 ppm. For γ‐chitin, two signals appeared around 73 and 75 ppm. From the X‐ray diffraction results, α‐chitin was observed to have four crystalline reflections at 9.6, 19.6, 21.1, and 23.7 by the crystalline structure. Also, β‐chitin was observed to have two crystalline reflections at 9.1 and 20.3 by the crystalline structure. γ‐Chitin, having an antiparallel and parallel structure, was similar in its X‐ray diffraction patterns to α‐chitin. The exothermic peaks of α‐chitin, β‐chitin, and γ‐chitin appeared at 330, 230, and 310, respectively. The thermal decomposition activation energies of α‐chitin, β‐chitin, and γ‐chitin, calculated by thermogravimetric analysis, were 60.56, 58.16, and 59.26 kJ mol−1, respectively. With the Arrhenius law, ln β was plotted against the reciprocal of the maximum decomposition temperature as a straight line; there was a large slope for large activation energies and a small slope for small activation energies. α‐Chitin with high activation energies was very temperature‐sensitive; β‐Chitin with low activation energies was relatively temperature‐insensitive. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3423–3432, 2004
Synthesis and nuclear magnetic resonance analysis of starch‐g‐poly(1,4‐dioxan‐2‐one) copolymers
Authors: Wang Xiu‐Li , Yang Ke‐Ke , Wang Yu‐Zhong , Zhou Zhi‐Xuan , Jin Yong‐Dong 
Published: June 2004

AbstractA new biodegradable starch graft copolymer, starch‐g‐poly(1,4‐dioxan‐2‐one), was synthesized through the ring‐opening graft polymerization of 1,4‐dioxan‐2‐one onto a starch backbone. The grafting reactions were conducted with various 1,4‐dioxan‐2‐one/starch feed ratios to obtain starch‐g‐poly(1,4‐dioxan‐2‐one) copolymers with various poly(1,4‐dioxan‐2‐one) graft structures. The microstructure of starch‐g‐poly(1,4‐dioxan‐2‐one) was characterized in detail with one‐ and two‐dimensional NMR spectroscopy. The effect of the feed composition on the resulting microstructure of starch‐g‐poly(1,4‐dioxan‐2‐one) was investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3417–3422, 2004