bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matrix metalloproteinases in neuromuscular disease
Authors: Renaud Susanne , Leppert David 
Published: April 2007

AbstractMatrix metalloproteinases (MMPs), a family of zinc‐dependent endoproteinases, are effector molecules in the breakdown of the blood–brain and blood–nerve barrier, and promote neural tissue invasion by leukocytes in inflammatory diseases of the central and peripheral nervous systems. Moreover, MMPs play an important role in synaptic remodeling, neuronal regeneration, and remyelination. Recent work concerning MMPs in patients with neuropathy, myopathy, spinal cord injury, and amyotrophic lateral sclerosis (ALS), and in corresponding animal models, is discussed in this review. Muscle Nerve, 2007
The H reflex from the abductor brevis hallucis muscle in healthy subjects
Authors: Versino Maurizio , Candeloro Elisa , Tavazzi Eleonora , Moglia Arrigo , Sandrini Giorgio , Alfonsi Enrico 
Published: April 2007

AbstractIn order to evaluate the clinical applicability of a neurophysiological technique, information is required about the effect of technical and subjective factors on the measured parameters, and whether these measures are reliable. The reliability of measurement of a given parameter is inversely related to the variability shown by a set of measurements of that parameter made on the same subject under similar conditions. Reliable measures are fundamental to the clinical utility of any technique. We evaluated the reliability using the intraclass correlation coefficient (ICC), and assessed both single‐point and test–retest normal limits for H‐reflex parameters of abductor brevis hallucis (ABH). The H reflex from the ABH muscle was recorded in 36 of 43 subjects, but could not be elicited in 7 of 11 subjects who were >60 years of age. The Hmax latency increased as height increased, whereas Hmax amplitude and Hmax/Mmax amplitude ratio decreased as age and height increased. The Hmax latency and Hmax/Mmax amplitude ratio, but not Hmax amplitude, proved to be reliable. The usefulness of the H reflex from ABH in the evaluation of S2 radiculopathies is described. Muscle Nerve, 2007
Autosomal‐recessive and X‐linked forms of hereditary motor and sensory neuropathy in childhood
Authors: Ouvrier Robert , Geevasingha Nimeshan , Ryan Monique M. 
Published: April 2007

AbstractThe hereditary motor and sensory neuropathies (HMSNs, Charcot–Marie–Tooth neuropathies) are the most common degenerative disorders of the peripheral nervous system. In recent years a dramatic expansion has occurred in our understanding of the molecular basis and cell biology of the recessively inherited demyelinating and axonal neuropathies, with delineation of a number of new neuropathies. Mutations in some genes cause a wide variety of clinical, neurophysiologic, and pathologic phenotypes, rendering diagnosis difficult. The X‐linked forms of HMSN represent at least 10%–15% of all HMSNs and have an expanded disease spectrum including demyelinating, intermediate, and axonal neuropathies, transient central nervous system (CNS) dysfunction, mental retardation, and hearing loss. This review presents an overview of the recessive and X‐linked forms of HMSN observed in childhood, with particular reference to disease phenotype and neurophysiologic and pathologic abnormalities suggestive of specific diagnoses. These findings can be used by the clinician to formulate a differential diagnosis and guide targeted genetic testing. Muscle Nerve, 2007
Intraoperative muscle measurements reveal a relationship between contracture formation and muscle remodeling
Authors: Pontén Eva , Gantelius Stefan , Lieber Richard L. 
Published: April 2007

AbstractChildren with cerebral palsy often have spasticity of both the extensors and flexors, but how and why a flexion contracture of the wrist will develop during growth is not thoroughly understood. In order to understand the muscle adaptations that occur during contracture formation, the relationship between intraoperative sarcomere length and the extent of contracture was measured in 23 children (average age, 14.3 ± 2.9 years) undergoing tendon transfers involving the flexor carpi ulnaris (FCU) or extensor carpi radialis brevis (ECRB) muscles. For both ECRB and FCU, sarcomere lengths measured intraoperatively were longer compared to sarcomere lengths predicted from a regression relationship obtained from “control” patients with radial nerve injury (P < 0.001). The most interesting aspect of the long FCU sarcomere lengths measured was that there was a highly significant correlation between the degree of contracture formation and intraoperative sarcomere length (r2 = 0.5, P < 0.005). These data clearly show that greater contracture severity is associated with longer intraoperative FCU sarcomere length. No such correlation was observed for the ECRB. The data suggest that the clinical presentation of the contracture is related to degree of FCU, but not ECRB adaptation, to the central nervous system lesion. Muscle Nerve, 2007
Properties of epoxy nanoclay system based on diaminodiphenyl sulfone and diglycidyl ether of bisphenol F: influence of post cure and structure of amine and epoxy
Authors: Ingram Sharon E , Liggat John J , Pethrick Richard A 
Published: April 2007

AbstractMaterials were prepared with Cloisite 30B, diglycidyl ether of bisphenol F and diaminodiphenyl sulfone (DDS) to investigate the relationship between exfoliation and property enhancement. A higher level of exfoliation was found with 4,4′‐DDS than in the material cured with 3,3′‐DDS. The material with 4,4′‐DDS that exhibited a higher degree of exfoliation also resulted in larger improvements in physical properties with nanoclay. Increasing the ratio of trifunctional to difunctional epoxy led to a significant decrease in the level of clay dispersion. Increasing the ratio of trifunctional epoxy in the nanocomposite also caused a decrease in Tg with the addition of nanoclay. However, an increase in Tg with increasing clay loadings was detected in samples with a higher degree of exfoliation, with only difunctional epoxy. Similar behaviour was found for samples with and without a post cure. Excessive post cure led to a decrease in thermal stability in Cloisite 30B‐containing samples. Copyright © 2007 Society of Chemical Industry
Polymerizable oil‐in‐oil emulsions: poly(vinyl pyrrolidone) dispersions in reactive PDMS medium
Authors: Hariri Kamal , Al Akhrass Samer , Delaite Christelle , Moireau Patrick , Riess Gérard 
Published: April 2007

AbstractThe system N‐vinyl‐2‐pyrrolidone (VP)/polydimethylsiloxane diglycidylether (PDMS‐DGE) is a typical example of an oil‐in‐oil emulsion formed by two non‐miscible liquids, where both phases are polymerizable in a ‘one‐pot’ procedure by two distinct reaction mechanisms. These oil‐in‐oil emulsions were characterized by their stability and by the particle size of the dispersed VP phase. Non‐aqueous dispersions (NADs) are obtained in a first step by free radical polymerization of the dispersed VP phase. The reaction kinetics, studied as a function of the initiator type and concentration, show that the polymerization rate is mainly influenced by the partition coefficient of the initiator between both phases. The NAD particle size could be tailored from a micrometer to a nanometer range by in situ formation of PVP‐PDMS graft copolymer. Hydrophilic–hydrophobic two‐phase materials can be obtained by polycondensation, in the presence of polyamines, of the epoxy‐functionalized PDMS continuous NAD phase. Copyright © 2007 Society of Chemical Industry
Bicyclo‐orthoester as a low‐shrinkage additive in cationic UV curing
Authors: Sangermano Marco , Malucelli Giulio , Delleani Gabriele , Priola Aldo 
Published: April 2007

AbstractA commercially available bicyclo‐orthoester (BOE) was used as low‐shrinkage additive for cationic UV curing of epoxy resins. A high reactivity of BOE by ring‐opening homopolymerization has been observed under cationic UV curing conditions. The BOE and trimethylolpropane triglycidyl ether monomers are compatible and give rise to a cured copolymeric network, under UV irradiation, with a flexibilization increase by increasing the BOE content in the photocurable formulation. Shrinkage after photopolymerization shows a linear reduction by increasing the BOE content in the photocurable formulation; a volume expansion upon polymerization is reached in the presence of 50 wt% of the additive. Copyright © 2007 Society of Chemical Industry
Fracture toughness evaluation of K resin® grafted with maleic anhydride‐ compatibilized polyamide 6/K resin® blends
Authors: Jing Bo , Dai Wenli , Liu Pengsheng , Zhang Ping 
Published: April 2007

AbstractThe mechanical behavior and fracture toughness of polyamide 6 (PA6)/K resin® (K) blends, with and without maleic anhydride‐grafted K resin® (K‐g‐MAH) incorporated, have been investigated. The results showed that the tensile strength, elongation at break and impact strength of PA6/K blends were improved considerably on incorporating K‐g‐MAH. This results from the improvement of compatibility between the PA6 and K phases. The essential work of fracture (EWF) method was employed to determine the fracture toughness of PA6/K blends with and without K‐g‐MAH incorporated. The effect of composition on the EWF parameters of the blends was particularly investigated. The results showed that a significant improvement in the specific EWF (we) of PA6/K blends occurred when K‐g‐MAH was incorporated. The effect of K‐g‐MAH content on the fracture toughness of the PA6/K/K‐g‐MAH blends was mainly achieved through its influence on the specific essential and nonessential work of fracture in the yielding process. Copyright © 2007 Society of Chemical Industry
Glass transition of poly(oxymethylene)
Authors: Suzuki Hidematsu , Grebowicz Janusz , Wunderlich Bernhard 
Published: April 2007

AbstractHeat capacity data of semicrystalline poly(oxymethylene) samples. Delrin and Celcon, are analysed in order to discuss the glass transition behaviour of this polymer. There are two types of non‐crystalline poly(oxymetheylene). the mobile and rigid amorphous parts. The glass transition of the former occurs in a rather wider range of temperature: it starts at 180 K and could end at 265 K. The latter, under restraint due to the crystallites, remains frozen up to the melting temperature.
1H n.m.r. spectra of ring‐opened polymers of 1‐methylbicyclo[2.2.1]hept‐2‐ene
Authors: Hamilton James G. , Ivin Kenneth J. , Rooney John J. 
Published: April 2007

Abstract1H n.m.r. spectra of the title polymers containing 0%, 57% and 100% cis double bonds and having various degrees of head‐tail (HT) bias have been analysed. The olefinic protons give distinct signals for HH, HT and TT trans dyads, also for HT and TT cis dyads, but HH cis dyads are not present in any polymer. The ring protons adjacent to the double bonds also give distinct cis and trans signals as do the methyl protons. The latter give four lines, assigned to cc, ct, tc and tt double bond pairs, and their intensities indicate a somewhat blocky cis/trans distribution for polymers having a high cis content. There is no fine structure which can be positively assigned to ring tacticity effects.
Structure and properties relationships of epoxy resins part 1: Crosslink density of cured resin: (I) model resins synthesis
Authors: Chung  , Lau H. , Hodd Kenneth A. , Wright William W. 
Published: April 2007

AbstractTwo model epoxy resin precursors based on the N‐glycidyl derivatives of 4.4'‐diaminodiphenylene methane (DDM) were prepared: N,N bis‐(2,3‐epoxypropyl)‐N′,N″‐dimethyl‐4.4'‐diaminodiphenylene methane (G2A); N.N′ bis‐(2,3‐epoxypropyl)‐N,N′‐dimethyl‐4,4'‐diaminodiphenylene methane (G2S). To prepare these, aniline or N‐methyl aniline was reacted with epichlorohydrin, using acetic acid as catalyst. The products were coupled via acid‐catalysed condensations in the presence of formaldehyde or with N,N‐dimethylaminobenzyl alcohol. The coupled chlorohydrins formed were then dehydrochlorinated to form the desired product. All reactions were monitored and purifications of the crude products were effected by high pressure liquid chromatographic techniques. The products were characterised by proton and carbon‐13 nuclear magnetic resonance, infrared and mass spectroscopy, elemental and titrametric analysis. Results were compared with those obtained for tetra‐N‐glycidyl‐4,4'‐diaminodiphenylene methane (TGDDM). All the data confirmed the structures of the model resins. These, together with TGDDM. will be used to prepare epoxy resin networks of controlled crosslink density and chemical homogeneity.
Comb‐branched poly(alkyl itaconates) containing pendant ethylene amine groups
Authors: Cowie John M. G. , Wadi Nabil M. A. 
Published: April 2007

AbstractComb‐branched copolymers containing ethylene amine side chains of the general structure ‐NH(CH2CH2NH)xH with x=1, 2, 3 and 4, were prepared by the reaction of poly(monoalkyl‐codialkyl itaconate)s, using an excess of the appropriate diamine in the presence of dicyclohexylcarbo‐diimide. Incorporation of ethylene amine units in the itaconate copolymers resulted in an increase in the glass transition temperature (Tg) and in the complex modulus of the modified copolymers above Tg. Both effects were proportional to the ethylene amine content of the copolymers. Chemical modification also occurred when samples were heated to about 450 K when imide formation was detected.
X‐ray scattering from directionally crystallised pentadecaethylene glycol di‐n‐heneicosyl ether
Authors: Swales Timothy G. E. , Yeates Stephen G. , Booth Colin 
Published: April 2007

AbstractX‐ray scattering from continuously rotated samples of directionally crystallised pentadecaethylene glycol di‐n‐heneicosyl ether falls on a pattern of layer lines which is readily interpreted. The unit cell is orthogonal with a=0.938nm. b=9.13nm and c=0.916nm. and with four molecules per unit cell.
Studies on chitin 3—effect of coagulants and annealing on the preparation and the properties of chitin membrane
Authors: Aiba Sei‐Ichi , Izume Masato , Minoura Norihiko , Fujiwara Yukihiko 
Published: April 2007

AbstractChitin membrane was prepared by casting a N,N‐dimethyl acetamide, N‐methyl 2‐pyrrolidone and lithium chloride (DMA‐NMP‐LiCl)solution of chitin and coagulating with several media. The effect of the coagulants on membrane formation was studied. 2‐Propanol was found to be more favourable than methanol, ethanol, acetone and mixtures of 2‐propanol and water. The membrane obtained in 2‐propanol was subjected to annealing. Annealing made the membrane dense and strong. The tensile strength of the membrane annealed at 145°C for 2hr was about twice that of an unannealed membrane. The solute permeability of the annealed membranes was lower than that of the original one. These phenomena could be clearly interpreted in terms of crystallinity.
The radiation crosslinking and scission of ethylene‐propylene copolymers studied by solid‐state nuclear magnetic resonance
Authors: O'Donnell James H. , Whittaker Andrew K. 
Published: April 2007

AbstractMethyl groups from chain scission and H‐crosslinks have been identified by solid‐state nuclear magnetic resonance in amorphous ethylene‐propylene copolymers containing 23 and 36 mole % propylene after γ‐irradiation to 10 MGy at 30°C. G (scission) and G (crosslink) values determined from the n.m.r. spectra and by extraction are in agreement, which suggests that the crosslinks are not clustered. This may differ from the situation in polyethylene where there is a substantial crystalline content. G(S). G(X) and the ratio G(S)/G(X) increase with increasing propylene content of the copolymers.
Bioactive polymers XXIX—immobilisation of α‐amylase on Biozan R
Authors: Dumitriu Severian , Popa Marcel 
Published: April 2007

AbstractThe immobilisation of α‐amylase (E.C.3.2.1.1) on Biozan R with dicyclohexyl carbodiimide as an activator has been studied. The reaction was proved to be influenced by the enzyme support and activator support ratios as well as by the reaction duration. The function correlating the coupled enzyme activity with process parameters was derived by processing the experimental results obtained by means of a second order, composite, centrate, rotatable experimental design, using the multiple regression method. The activity of the coupled enzyme was dependent on the temperature and pH of the incubation reaction. The Michaelis‐Menten constant is higher for the immobilised enzyme as compared with the free one.
Continuous alcohol production from whey permeate using immobilised cell reactor systems
Authors: Marwaha Satwinder S. , Kennedy John F. 
Published: April 2007

AbstractThe present paper reports the performance of a bioreactor packed with alginate‐entrapped Kluyveromyces marxianus NCYC179 for continuous fermentation of whey permeate to ethanol. A maximum ethanol productivity as 28.21 gl−1 h−1 was attained at D=0.42h−1 and 75% lactose consumption (substrate feed rate in the inflowing medium was 200 g lactose I−1). However, the higher dilution rates (0.6‐1.Oh−1) resulted in poor productivities and higher substrate washout in the effluent samples. The maximum specific ethanol production (qpi) and maximum specific lactose uptake (qsi) of the immobilised Kluyveromyces marxianus NCYC179 was found to be 3.88g ethanol/g immobilised cell/hx10−2 and 8.75g lactose consumed/g immobilised cell/hx10−2 respectively. A bead size of 2.5 mm in diameter and activation period of 24h of alginate beads in lactose solution (10%) prior to their packing in column reactor were found to support the efficient working of the bioreactor. The immobilised cell bioreactor system was operated continuously at a constant dilution rate of 0.15h−1 and 10% lactose for 562 h without any significant change in the efficiency (varied from 84 to 88% of theoretical) and viability of the entrapped yeast cells (dropped from 84 to 81%).
Differential scanning calorimetric investigation of polymerisation of epoxy resin based on phenolphthalein with phthalic anhydride
Authors: Shah Praful P. , Parsania Pursottam H. , Patel Shanti R. 
Published: April 2007

AbstractPolymerisation of phenolphthalein‐based epoxy resin with phthalic anhydride has been investigated by differential scanning calorimetry. The overall polymerisation kinetics were found to be independent of the concentration of phthalic anhydride and scan rate. The polymerisation was found to follow a simple Arrhenius‐type temperature dependence up to about 80% completion.
Effects of hydrolysis on the physical properties of short glass‐fibre reinforced poly(ethylene terephthalate)
Authors: Haworth Barry , Walsh Geraldine M. 
Published: April 2007

AbstractThe mechanical fracture strength and toughness of short‐fibre composites, injection moulded from compounds of poly(ethylene terephthalate) (PET) containing 10 and 30% (by weight) (w/o) glass, have been investigated and the dependence upon matrix hydrolytic stability determined. Mouldings have been characterised by several physical techniques to evaluate molecular weight, degradation rates, crystallinity and morphology, whilst time‐dependent gravimetric data were derived to quantify sorption kinetics and allow comparisons with theoretical reaction rates to be made. During melt processing, PET is hydrolysed extremely rapidly by traces of moisture (<0.02w/o). yet the inherent strength of moulded composites declines significantly only below an apparently critical molecular weight. However, on long‐term humid ageing in hot water, impact behaviour especially is rendered more complex by simultaneous crystallisation, molecular reorder and losses of interfacial bond strength.
Orientation‐strain behaviour of crosslinked rubbers
Authors: Mitchell Geoffrey R. 
Published: April 2007

AbstractProcedures for the evaluation of quantitative orientation parameters using wide‐angle x‐ray scattering data are outlined. Data are presented for crosslinked natural rubber. a copolymer of polyethylene and polyvinylacetate and for polymethylmethacrylate. These quantitative orientation data are compared to the predictions of models of rubber elasticity. Critical comparisons are made with affine and phantom chain models and the variable network constraint model recently introduced by Erman and Flory. The effects of entanglements and segmental interactions are also considered. An approach is introduced which allows the evaluation of the level of intersegmental interaction contribution to the orientation‐strain behaviour.
Molecular models of polymer networks and constitutive equations of rubber elasticity
Authors: Ziabicki Andrzej , Walasek Janusz 
Published: April 2007

AbstractEquilibrium elastic behaviour of crosslinked polymers (networks) is analysed both from the macroscopic (phenomenological) and microscopic (molecular) points of view. Molecular mechanisms possibly responsible for non‐linear rubber elasticity are discussed. They include: conformational entropy of network chains at small and large extensions, hindered rotation of such chains and intra‐chain point interactions, dipole‐dipole interactions between asymmetric chain segments, and topological constraints leading to chain entanglement.
Dynamical considerations of network properties
Authors: Edwards S. F. 
Published: April 2007

AbstractElasticity is discussed as an aspect of viscoelasticity, which is described by the tube model. The effects of both crosslinks and entanglements contribute to this model and a discussion of how these effects can be quantified is given. At high enough concentration, entanglements ensure the existence of elastic effects even without crosslinks, and a theory is presented on how this dynamical phase change comes about.
The continuous‐time random walk description of the non‐equilibrium mechanical response of crosslinked elastomers
Authors: Gaylord Richard J. , Joss Brian , Bendler John T. , Dimarzio Edmund A. 
Published: April 2007

AbstractThe application of the continuous‐time random walk model to the description of the non‐equilibrium stress response of a crosslinked network is discussed. Different versions of the continuous‐time random walk model lead to the prediction of a stress relaxation function having either a fractional‐power law form or a fractional‐exponential law form. Both forms are tested against experimental data on the stress relaxation and loss modulus behaviours of crosslinked natural rubber.
Non‐equilibrium mechanical properties of model networks
Authors: Kramer Ole 
Published: April 2007

AbstractA large number of specially prepared model networks with different types of network defects have been produced since de Gennes proposed the reptation motion for linear chains. The viscoelastic properties of these model networks show clearly that branched chains and dangling chains are the cause of the gradual and extremely slow relaxations in lightly crosslinked networks. These experimental results have been followed by theoretical developments that point towards a complete molecular theory for the non‐equilibrium properties of lightly crosslinked networks. It is proposed that the presence of dangling chains in endlinked networks may be revealed by measurements of the viscoelastic properties of such networks near the transition zone.
Thermoviscoelastic behaviour of EPDM elastomers in chemical and physical networks
Authors: Scholtens Boudewijn J. R. 
Published: April 2007

AbstractIn this study two aspects of the thermoviscoelasticity of EPDM elastomers are discussed, namely their complex behaviour as a result of the presence of (micropara)crystallinity, and the dependence of the time‐temperature shift functions on the crosslink density.