bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nerve excitability properties in lower‐limb motor axons: Evidence for a length‐dependent gradient
Authors: Krishnan Arun V. , Lin Cindy S.‐Y. , Kiernan Matthew C. 
Published: April 2004

AbstractIn this study, nerve excitability protocols were adapted for lower‐limb recordings in 25 healthy subjects to enable comparison of excitability parameters between proximal and distal recording sites of the same nerve and between different nerves. Excitability parameters (stimulus–response curves, strength–duration properties, threshold electrotonus, a current–threshold relationship, and the recovery cycle) were recorded from tibialis anterior, extensor digitorum brevis, and abductor hallucis. Excitability recordings were technically possible from each site, and normative values were established for lower‐limb nerves. In this process, inter‐ and intranerve differences in excitability properties were demonstrated: stimulus intensity and rheobase were reduced in recordings from proximal sites; the relative refractory period and late subexcitability were increased; superexcitability was reduced; and a relative “fanning‐in” occurred for threshold electrotonus curves recorded from proximal sites. Such a length‐dependent gradient in nerve excitability may underlie the greater tendency for ectopic activity to arise from the proximal segments of motor axons and may contribute to the length‐dependent involvement of motor axons in the development of peripheral neuropathy. Muscle Nerve 29: 645–655, 2004
Effect of creatine supplementation on skeletal muscle of mdx mice
Authors: Louis Magali , Raymackers Jean Marc , Debaix Huguette , Lebacq Jean , Francaux Marc 
Published: April 2004

AbstractDystrophic mice (mdx) and their controls (C57/Bl10) were fed for 1 month with a diet with or without creatine (Cr) enrichment. Cr supplementation reduced mass (by 19%, P < 0.01) and mean fiber surface (by 25%, P < 0.05) of fast‐twitch mdx muscles. In both strains, tetanic tension increased slightly (9.2%) without reaching statistical significance (P = 0.08), and relaxation time increased by 16% (P < 0.001). However, Cr had no protective effect on the other hallmarks of dystrophy such as susceptibility to eccentric contractions; large numbers of centrally nucleated fibers in tibialis anterior; and elevated total calcium content, which increased by 85% (P = 0.008) in gastrocnemius mdx muscles. In conclusion, Cr may be a positive intervention for improving function of dystrophic muscle. Muscle Nerve 29: 687–692, 2004
The challenge of public sector reform in EC accession countries: reflections from the Baltics, especially Latvia
Authors: Jacobs Colin 
Published: April 2004

AbstractThis article considers some of the key issues in reforming the public sector in Central and Eastern Europe (CEE). Drawing on the experience of donor funded projects, some conclusions are drawn about the process of public sector reform with particular reference to Latvia. In particular, it is argued that the process will take time but strategic choices need to be made in the absence of obvious demands from within the country. Several constraints are noted which together constitute formidable barriers to progress. However, the results of work to date provide some optimism for pilot approaches to strategic budgeting in reformist ministries. A simple checklist is used as a yardstick for progress in the main areas of public administration reform. Copyright © 2004 John Wiley & Sons, Ltd.
Gastrointestinal stromal tumours (GISTs) negative for KIT (CD117 antigen) immunoreactivity
Authors: Debiec‐Rychter Maria , Wasag Bartosz , Stul Michel , De Wever Ivo , Van Oosterom Allan , Hagemeijer Anne , Sciot Raf 
Published: April 2004

AbstractGastrointestinal stromal tumours (GISTs) are currently defined as mesenchymal tumours of the gastrointestinal tract that express KIT receptor tyrosine kinase. However, a small subgroup of tumours that fulfil the clinical and morphological criteria for GISTs lack KIT expression. So far, the biological features of these tumours have rarely been addressed. The present study describes seven gastrointestinal stromal neoplasms that presented clinicopathological features typical of GISTs but showed absence of CD117 expression as detected by immunohistochemistry. The tumours originated from the stomach (n = 5), duodenum (n = 1), and colon (n = 1), showing histologically either predominantly epithelioid (n = 3), mixed spindled and epithelioid (n = 2), or anaplastic/spindle cell (n = 2) type features. CD34 and α‐smooth muscle actin (α‐SMA) positivity was present in four and three tumours, respectively. Chromosomal analysis was performed in two cases, both showing losses of chromosomes 14, 22, and 1p, which is the characteristic feature of GISTs. Dual‐colour interphase fluorescence in situ hybridization (FISH) analysis, utilizing chromosome 1p‐, 14‐, and 22‐specific probes, revealed a similar cytogenetic profile in the remaining five tumour specimens. Mutational analysis of exons 9, 11, 13, and 17 of KIT, and exons 12 and 18 of PDGFRA was performed in all cases by denaturing high‐pressure liquid chromatography (DHPLC) pre‐screening, followed by direct sequencing. None of the tumours showed KIT mutant isoforms. Three tumours harboured PDGFRA exon 18 activating mutations; two were Asp → Val842 missense substitutions and one was a DIM842–844 amino acid deletion. KIT and PKCθ (protein activated in interstitial cells of Cajal and GISTs) expression was determined by western immunoblotting of the total cell lysates from three tumour biopsies. None of these three tumours expressed KIT, while all specimens showed expression of PKCθ protein. These findings indicate that there is a subgroup of KIT‐negative GISTs that exhibit the same morphological, cytogenetic, and molecular features as KIT‐positive tumours. While intragenic PDGFRA activating mutations are present in some of these tumours, the oncogenic events underlying the pathogenesis of the others remain unknown. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Modification of recycled high‐density polyethylene by low‐density and linear‐low‐density polyethylenes
Authors: Kukaleva N. , Simon G. P. , Kosior E. 
Published: April 2004

AbstractThe present study investigated mixed polyolefin compositions with the major component being a post‐consumer, milk bottle grade high‐density polyethylene (HDPE) for use in large‐scale injection moldings. Both rheological and mechanical properties of the developed blends are benchmarked against those shown by a currently used HDPE injection molding grade, in order to find a potential composition for its replacement. Possibility of such replacement via modification of recycled high‐density polyethylene (reHDPE) by low‐density polyethylene (LDPE) and linear‐low‐density polyethylene (LLDPE) is discussed. Overall, mechanical and rheological data showed that LDPE is a better modifier for reHDPE than LLDPE. Mechanical properties of reHDPE/LLDPE blends were lower than additive, thus demonstrating the lack of compatibility between the blend components in the solid state. Mechanical properties of reHDPE/LDPE blends were either equal to or higher than calculated from linear additivity. Capillary rheological measurements showed that values of apparent viscosity for LLDPE blends were very similar to those of the more viscous parent in the blend, whereas apparent viscosities of reHDPE/LDPE blends depended neither on concentration nor on type (viscosity) of LDPE. Further rheological and thermal studies on reHDPE/LDPE blends indicated that the blend constituents were partially miscible in the melt and cocrystallized in the solid state.
The importance of timely polymer sintering while processing polypropylene foams in rotational molding
Authors: Pop‐Iliev Remon , Rizvi Ghaus M. , Park Chul B. 
Published: April 2004

AbstractProducing polypropylene (PP) foams with satisfactory cell morphologies in rotational foam molding is feasible. However, the narrow interval between the melting temperature of PP and the onset decomposition temperature of the applicable chemical blowing agent (CBA), and the relatively low melt strength of PP at elevated temperatures are considered the greatest obstacles in processing PP foams. The experimental results revealed that the morphology of the foams obtained by processing PP pellets that have been pre‐compounded with a CBA could be governed by either pellet sintering or cell coalescence. The viscosity of the basic PP resin and the processing temperature determine which of these two key factors will assume a predominating influence towards the foaming process. The desired volume expansion ratio (VER) of the foam also plays an important role since it determines the formulation of the foamable resin and the shot size. Desirable PP foam structures in compounding based rotational foam molding can be obtained only if pellet sintering takes place prior to the decomposition of the CBA and if the processing temperature during the foaming process is kept lower than the temperature of cell coalescence.
A study of the stick‐slip phenomenon in single‐screw extrusion of linear polyethylene
Authors: Kay D. , Carreau P. J. , Lafleur P. G. , Robert L. , Vergnes B. 
Published: April 2004

AbstractWe present results of a study on the stick‐slip phenomenon observed for two linear polyethylenes (HDPE and LLDPE). Experiments were carried out in a single screw extruder using dies of different diameters and L/D ratios. The pressure and the mass flow rate have been measured simultaneously and the instant mass flow rate was determined using laser Doppler velocimetry. Our results clearly confirm the hypothesis that the flow jumps from one stable branch to the other during oscillations as suggested in the literature. The role of the melt compressibility in the reservoir is also established. The effect of the average mass flow rate imposed by the extruder QIN on the respective compression and decompression phases is in good agreement with effect predicted by the mass balance in the reservoir. We also used different reservoir volumes to confirm that the period of oscillations increases with the compressed melt volume upstream of the die.
Primary structure and physical properties of poly(ethylene terephthalate)/poly(ethylene naphthalate) resin blends
Authors: Maruhashi Yoshitsugu 
Published: April 2004

AbstractThe morphology and properties of blends of poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) that were injection molded under various conditions were studied. Under injection molding conditions that make it possible to secure transparency, blends did not show clear crystallinity at blending ratios of more than 20 mol% in spite of the fact that crystallinity can be observed in the range of PEN content up to 30 mol%. Because both transparency and crystallinity could be secured with a PEN 12 mol% blend, this material was used in injection molding experiments with various injection molding cycles. Whitening occurred with a cycle of 20 sec, and transparency was obtained at 30 sec or more. This was attributed to the fact that transesterification between PET and PEN exceeded 5 mol% and phase solubility (compatibility) between the PET and PEN increased when the injection molding time was 30 sec or longer. However, when the transesterification content exceeded 8 mol%, molecularly oriented crystallization did not occur, even under stretching, and consequently, it was not possible to increase the strength of the material by stretching. PET/PEN blend resins are more easily crystallized by stretch heat‐setting than are PET/PEN copolymer resins. It was understood that this is because residual PET, which has not undergone transesterification, contributes to crystallization. However, because transesterification reduces crystallinity, the heat‐set density of blends did not increase as significantly as that of pure PET, even in high temperature heat‐setting. Gas permeability showed the same tendency as density. Namely, pure PET showed a substantial decrease in oxygen transmission after high temperature heat‐setting, but the decrease in gas permeability in the blend material was small at heat‐set temperatures of 140°C and higher.
Industrial solidification processes in polybutene‐1. Part II—influence of shear flow
Authors: Braun J. , Wippel H. , Eder G. , Janeschitz‐Kriegl H. 
Published: April 2004

AbstractFollowing some early rudimentary results on shear‐induced crystallization of polybutene‐1 (1, 2), the present paper contains more detailed results. In the course of this work the origins of the highly oriented crystalline surface layers, as well known from injection molded samples, are more closely investigated. For the purpose, a special extrusion experiment is used, in which melts of various degrees of undercooling are moved through a duct of large aspect ratio. When, after the release of the pressure at the die entry, a quench of the duct to a temperature far below the melting point is delayed, a relaxation phenomenon is observed, in accordance with the experiences with i‐PP. From these experiments one learns that the leading parameter of the process is something like the mechanical work done per unit volume, and that the relaxation time increases with decreasing temperature much faster than the viscosity of the melt. The results are qualitatively in excellent agreement with our previously obtained results for polypropylene.
Nylon 10 10–montmorillonite nanocomposite made by intercalating polymerization
Authors: Zhang Guosheng , Li Yongjin , Yan Deyue , Xu Youyong 
Published: April 2004

AbstractNylon 10 10–montmorillonite nanocomposite has been prepared successfully using intercalating polymerization. The nanocomposite was investigated by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), Atom force microscopy (AFM), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), Differential scanning calorimeter (DSC), and Dynamic mechanical analysis (DMA). The results show that there are uniformly dispersed silicate layers in the nylon 10 10 matrix. The resulting nanocomposites have higher onset decomposition temperature and dynamic storage moduli than those of pure nylon 10 10. In addition, it was found that montmorillonite plays an important role in heterophase nucleation of the crystallization of nylon 10 10 in composites. Mechanical testing shows that the tensile modulus of nanocomposites is superior to that of nylon 10 10, and the ultimate strain values of the nanocomposites remain at a level similar to nylon 10 10 if the content of montmorillonite is not more than 6 wt%.
Numerical simulation of the flow in an extensional flow mixer. Effect of fluid elasticity on the flow
Authors: Tanoue Shuichi , Iemoto Yoshiyuki 
Published: April 2004

AbstractWe discuss the viscoelastic flow of the matrix fluid in an Extensional Flow Mixer (EFM) obtained by a numerical simulation. The effect of the fluid viscoelasticity on the flow state in an EFM was considered by the comparison of the flow states of the purely viscous fluid and the viscoelastic fluid. The mixing performance of the EFM is also considered. The Phan‐Thien Tanner model was used as the constitutive equation of the viscoelastic fluid and the Carreau model was used as that of the purely viscous fluid. Results obtained are as follows: (1) Stagnation flows occur in the converging‐diverging plates (c‐d plates) in the case of viscoelastic fluid. The size of stagnation flow region becomes large when the fluid has a strain‐thickening elongational viscosity. (2) The absolute value of the extensional strain and the pressure drop in the c‐d region increase with fluid elasticity. Meanwhile, the residence time in the c‐d region decreases with that. (3) There is no stagnation region in the c‐d plates for a purely viscous fluid. The stagnation flow has an effect on the estimation value of EFM's performance. The prediction by the purely viscous fluid is not useful for the flow in an EFM because of extremely low accuracy.
Effect of ground fluororubber vulcanizate powder on the properties of fluororubber compound
Authors: Ghosh Arun , Bhattacharya A. K. , Bhowmick A. K. , De S. K. 
Published: April 2004

AbstractFluororubber vulcanizate powder (FVP) obtained from fluororubber based on tetrafluoroethylene/propylene/vinylidene fluoride terpolymer by mechanical grinding exists in a highly aggregated chain‐like structure. X‐ray photoelectron spectros‐copy (XPS) and infrared (IR) spectroscopy studies show that there are no chemical change on the rubber surface following mechanical grinding of the fluororubber vulcanizate after heat aging at 200°C for 10 days. The incorporation of FVP as a filler in the fluororubber compound results in a marginal increase of Mooney viscosity, Mooney scorch time and shear viscosity. While tensile strength, modulus and hardness marginally increase on addition of FVP into the fluororubber compound, tear strength decreases. Rhemetric studies show that FVP alone is susceptible to further crosslinking in the presence of a curing agent. Dynamic mechanical spectra reveal that the glass to rubber transition temperature shifts higher by the addition of FVP into the fluororubber compounds. Atomic force microscopy (AFM) images show uniform dispersion of FVP particles into the rubber matrix.
Recycling of silicone rubber waste: Effect of ground silicone rubber vulcanizate powder on the properties of silicone rubber
Authors: Ghosh Arun , Rajeev R. S. , Bhattacharya A. K. , Bhowmick A. K. , De S. K. 
Published: April 2004

AbstractThe silicone rubber vulcanizate powder (SVP) obtained from silicone rubber by mechanical grinding exists in a highly aggregated state. The particle size distribution of SVP is broad, ranging from 2 µm to 110 µm with an average particle size of 33 µm. X‐ray Photoelectron Spectroscopy (XPS) and Infrared (IR) Spectroscopy studies show that there is no chemical change on the rubber surface following mechanical grinding of the heat‐aged (200°C/10 days) silicone rubber vulcanizate. Addition of SVP in silicone rubber increases the Mooney viscosity, Mooney scorch time, shear viscosity and activation energy for viscous flow. Measurement of curing characteristics reveals that incorporation of SVP into the virgin silicone rubber causes an increase in minimum torque, but marginal decrease in maximum torque and rate constant of curing. However, the activation energy of curing shows an increasing trend with increasing loading of SVP. Expectedly, incorporation of SVP does not alter the glass‐rubber transition and cold crystallization temperatures of silicone rubber, as observed in the dynamic mechanical spectra. It is further observed that on incorporation of even a high loading of SVP (i.e., 60 phr), the tensile and tear strength of the silicone rubber are decreased by only about 20%, and modulus dropped by 15%, while the hardness, tension set and hysteresis loss undergo marginal changes and compression stress‐relaxation is not significantly changed. Atomic Force Microscopy studies reveal that incorporation of SVP into silicone rubber does not cause significant changes in the surface morphology.
Study of the different flow patterns in the melting section of a co‐rotating twin‐screw extruder
Authors: Yichong Guo , Fuhua Zhu 
Published: April 2004

AbstractUnderstanding the phenomena of twin‐screw extrusion (TSE) is the first step in investigating this process. Visualization technology incorporated in a co‐rotating twin‐screw extruder was developed for this purpose. This technology enabled the extrusion phenomena to be directly observed and analyzed. The present work focuses on the melting process. It is revealed and verified that there are different flow patterns in the melting section during extrusion, with different degrees of fill. A melting model for one type of flow pattern is established. The significance of the present work is to establish the variety conception for the flow patterns. According to this conception, corresponding models should be established for each flow pattern identified.
Study on composition and characteristics of maleated ethylene‐octene copolymer prepared by reactive extrusion on the morphology and properties of polyamide 6/ethylene‐octene copolymer blends
Authors: Premphet‐Sirisinha K. , Chalearmthitipa S. 
Published: April 2004

AbstractBlends of polyamide 6 (PA6) and elastomeric ethylene‐octene copolymer (EOR), with and without maleated EOR (EOR‐MA) were studied. EOR‐MA with various amounts of grafted MA and gel content were prepared by reactive extrusion. The effects of EOR‐MA characteristics and composition on the morphology, thermal and mechanical properties of the blends were investigated. EOR‐MA was found to promote the toughness efficiency of PA6 remarkably. High impact resistance was achieved by the use of EOR‐MA containing less than 2% gel. The content of MA grafted on EOR‐MA in the range of 0.5%–1.0% gave a similar effect on the blend properties. The blend containing 20% of EOR grafted with 1% MA exhibited twenty times higher impact strength (1000 J/m) than pure PA6 (55 J/m). The presence of EOR‐MA in the blends led not only to a drastic reduction in the dispersed particle size, but also to some changes in fracture mechanisms, thus enhancing the impact resistance of the blends.
Rheological properties of hyperbranched polymer/poly(ethylene terephthalate) reactive blends
Authors: Kil Seung Bum , Augros Yannick , Leterrier Yves , Månson Jan‐Anders E. , Christel Andreas , Borer Camille 
Published: April 2004

AbstractThe rheological properties in solution, in shear and in uniaxial elongation of poly(ethylene terephthalate) (PET) reacted together with hyperbranched polymers (HBPs) were investigated. Two different PET grades, of low and high molecular weights, were compounded with sub‐ to over‐stoichiometric concentrations of HBPs of second and fourth pseudo‐generation, and subsequently subjected to a solid‐state polycondensation (SSP). The formation of microgels, which occurs at high HBP concentration, gave rise to a large increase in melt elasticity and a related decrease in melt strength. At low HBP concentrations, the complex viscosity of the unreacted HBP/PET was considerably reduced, thus demonstrating a lubrication effect of the HBP molecules. During SSP, the intrinsic and shear viscosities exhibited a gradual increase, which was similar for both PET and HBP/PET blends, and was correlated to an increase in molecular weight, through linear‐chain extension and branching reactions. The elongational viscosity of the reactive blends was also increased as a function of reaction time, and this increase was much larger in the case of the HBP/PET blends. A 400% increase in melt strength of the PET was obtained by combining SSP and trace amounts of an HBP of second generation, without any decrease in drawability.