bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corticotropin-Releasing Hormone (CRH)-Induced Thyrotropin Release Is Directly Mediated through CRH Receptor Type 2 on Thyrotropes
Authors: De Groef Bert , Goris Nesya , Arckens Lutgarde , Kühn Eduard R. , Darras Veerle M. 
Published: September 2003

Abstract
CRH is known as the main stimulator of ACTH release. In representatives of all nonmammalian vertebrates, CRH has also been shown to induce TSH secretion, acting directly at the level of the pituitary. We have investigated which cell types and receptors are involved in CRH-induced TSH release in the chicken (Gallus gallus). Because a lack of CRH type 1 receptors (CRH-R1) on the chicken thyrotropes has been previously reported, two hypotheses were tested using in situ hybridization and perifusion studies: 1) TSH secretion might be induced in a paracrine way involving melanocortins from the corticotropes; and 2) thyrotropes might express another type of CRH-R. For the latter, we have cloned a partial cDNA encoding the chicken CRH-R2. Neither α-melanotropin (α-MSH) nor its powerful analog Nle4,d-Phe7-MSH could mimic the in vitro TSH-releasing effect of ovine CRH. The nonselective melanocortin receptor blocker SHU91199 did not influence CRH- or TRH-induced TSH secretion. On the other hand, we have found that thyrotropes express CRH-R2 mRNA. The involvement of this CRH receptor in the response of thyrotropes to CRH was further confirmed by the fact that TSH release was stimulated by human urocortin III, a CRH-R2-specific agonist, whereas the TSH response to CRH was completely blocked by the CRH-R blocker astressin and the CRH-R2-specific antagonist antisauvagine-30. We conclude that CRH-induced TSH secretion is mediated by CRH-R2 expressed on thyrotropes.
Reduced Intratesticular Testosterone Concentration Alters the Polymerization State of the Sertoli Cell Intermediate Filament Cytoskeleton by Degradation of Vimentin
Authors: Show Matthew D. , Anway Matthew D. , Folmer Janet S. , Zirkin Barry R. 
Published: September 2003

AbstractThe Sertoli cell intermediate filament cytoskeleton is composed of the type III family member vimentin. The distribution of Sertoli cell vimentin varies with the stage of spermatogenesis, with shortening of the filaments at stages VII–VIII, the stages of spermiation. Experimental reduction in intratesticular testosterone (T) concentration also results in the sloughing of advanced spermatids from the Sertoli cells, as well as in the apoptotic death of spermatocytes. We hypothesized that alteration of the distribution of Sertoli cell vimentin might play a role in the loss of germ cells that occurs in response to reduced intratesticular T. To test this hypothesis, intratesticular T was reduced by implanting LH-suppressive SILASTIC brand capsules containing T and estradiol into adult rats for 8 wk. Immunohistochemical analyses revealed that, in response to the implants, the vimentin cytoskeleton collapsed around the Sertoli cell nuclei at all stages of the cycle, losing the extensive branching and structure normally seen at most stages of the cycle. Western blots of isolated Sertoli cells revealed that protein levels did not differ significantly between control and T- and estradiol-treated rats. However, Sertoli cell fractions containing the vimentin monomer revealed that vimentin was cleaved into four to five fragments in Sertoli cells in response to the implants, suggestive of proteolysis. These results indicate that, in response to reduced intratesticular T, the vimentin cytoskeleton of the Sertoli cell collapses to a perinuclear localization, and suggest that this collapse is associated with, and perhaps caused by, the degradation of the vimentin monomer rather than by loss of its expression.
On computational fluid dynamics modelling of crosswind effects for high-speed rolling stock
Authors: Diedrichs B 
Published: September 2003

This work addresses crosswind stability exemplified for the German Railway Deutsche Bahn AG high-speed train ICE 2. The scope of the work is to describe the flow by means of computational fluid dynamics past the leading two cars of the train for yaw angles in the range 12.2–40.0°. Three track formations are utilized. The basic results are the set of independent aerodynamic coefficients for the lead and subsequent cars. The results are to some extent compared with experimental data for ICE 2 and also with data obtained for the Swedish high-speed train X2000. A numerical sensitivity study is undertaken to quantify differences in the above results dependent on the grid density and quality, turbulence model, numerical scheme, location of inlet and outlet boundaries, turbulence intensity and flow simulation software.
Effect of preparation parameters on performance of dense homogeneous polycarbonate gas separation membranes
Authors: Hacarlioglu P. , Toppare L. , Yilmaz L. 
Published: September 2003

AbstractThe aim of this study is to determine the effect of preparation parameters on the membrane permeation mechanism and separation performances of dense homogeneous poly(bisphenol A carbonate) (PC) membranes. Blade‐casting and drop‐casting techniques are used for casting films from solutions with varying concentrations. Chloroform and methylene chloride are used to determine the effect of the properties of the casting solvent. Permeation measurements are done with Ar, N2, O2, CH4, CO2, and H2 gases. The selectivity values of dense homogeneous membranes with a PC composition of 7% (w/v chloroform) are 1.7 for Ar/N2, 1.1. for CH4/N2, 18 for CO2/N2, 26 for H2/N2, and 9.7 for O2/N2. These values with a PC composition of 15% (w/v methylene chloride) are 2.7, 1.3, 25, 44, and 13 for the same gases, respectively. In addition to the importance of the solvent type and composition, the casting type and thermal history also affects the performance of the membrane. Increasing the annealing period enhances the selectivity while decreasing the permeability for both casting solvents, yet this thermal history effect strongly depends on the solvent type because of solvent–polymer interactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 776–785, 2003
Investigation of crystallization behavior in dynamically vulcanized EPDM–nylon copolymer blends
Authors: Huang Hua , Liu Xin , Ikehara Takayuki , Nishi Toshio 
Published: September 2003

AbstractA thermoplastic vulcanizate (TPV) of a ethylene–propylene–diene terpolymer (EPDM) and nylon copolymer (PA) was prepared by dynamic vulcanization. Maleic anhydride (MAH)–grafted EPDM (EPDM–g–MAH), MAH‐grafted EPR (EPR–g–MAH), and chlorinated polyethylene (CPE) were used as compatibilizers. The effect of dynamic vulcanization and compatibilizer on the crystallization behavior of PA was investigated. Differential scanning calorimeter measurement results showed no pronounced shift in the crystallization temperature for PA in EPDM–PA TPV compared to that for PA in the neat state, whereas the crystallization temperature increased after adding compatibilizer. The decrease in the crystallinity of TPVs was a result of the crystallization occurring in confined spaces between rubber particles. The equilibrium melting temperature (Tm0) of the PA copolymer was measured and was determined to be 157°C. The isothermal crystallization kinetics of PA in the neat and TPV states also was investigated. The crystallization rate was highest in the compatibilized TPV and lowest in the neat PA, whereas it was intermediate in the uncompatibilized TPV unvulcanized blends. Compared with unvulcanized EPDM–PA blends, the dynamic vulcanization process seemed to cause an obvious increase in the crystallization rate of the PA copolymer, especially when a suitable compatibilizer was used. This occurred because the dynamic vulcanization introduced fine crosslinked rubber particles that could act as heterogeneous nucleating centers. In addition, the use of a suitable compatibilizer permitted the formation of finely dispersed vulcanized rubber particles and therefore increased the density of the nucleating centers. The complex morphology of the blends was investigated by atomic force microscopy to evaluate the effect of compatibilizer on the size of the dispersed rubber particles. Compared with the morphology of TPVs with the same dosage of EPDM–g–MAH compatibilizer, the morphology of TPVs using EPR–g–MAH as compatibilizer showed much smaller dispersed rubber particles, which may have contributed to the higher crystallization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 824–829, 2003
Preparation and properties of nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites
Authors: Chen‐Yang Y. W. , Chen S. F. , Yuan C. Y. , Lee H. F. , Li J. L. , Li C. Y. , Chiu Y. S. 
Published: September 2003

AbstractNew novel fire‐resistant and heat‐resistant cyclotriphosphazene‐containing polyimide resins were prepared in situ by the polymerization of (p‐aminophenoxy)(phenoxy)cyclotriphosphazenes with 3,3′,4,4′‐benzophenonetetracarboxylic acid or 3,3′,4,4′‐diphenylsulfonetetracarboxylic acid and a crosslink agent, 5‐norbornene‐2,3‐dicarboxylic acid and were used as polymer matrix compositing with a woven carbon fiber to prepare nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites. The thermal stability, flame retardance, morphology of the surface fracture, and some physical properties of the composites were investigated by thermogravimetric analysis, scanning electron microscopy, and a material testing system, respectively. The composites had good thermal stability, flame retardance, and mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 810–818, 2003
Synthesis and characterization of silica nanocomposite in situ photopolymerization
Authors: Xu Guo Cai , Li Ai Yuan , Zhang Li De , Wu Guo Sheng , Yuan Xiao You , Xie Ting 
Published: September 2003

AbstractThis study was carried out on nanocomposites consisting of nanometer silica fillers embedded in thermoset polymers that were prepared via the in situ polymerization of ultraviolet (UV) curable systems containing different contents of nanometer silicas by irradiation of UV light. Because of the introduction of nanosilicas, the curing rates of the UV curing of dispersing systems were played down; that is, the curing times were prolonged, but the mechanical properties of the nanocomposites, such as tensile strength and Young's modulus, increased, and the thermostability of the nanocomposites at temperatures lower than 400 K improved. The dispersing states of nanometer silicas within the polymer matrix were characterized by transmission electron microscopy, and the results show that the nanometer silicas had good homogeneously dispersing states within nanocomposites containing less than 3 wt % nanometer silicas. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 837–840, 2003
Compatibility of low‐density polyethylene/poly(ethylene‐co‐vinyl acetate) binary blends prepared by melt mixing
Authors: Takidis G. , Bikiaris D. N. , Papageorgiou G. Z. , Achilias D. S. , Sideridou I. 
Published: September 2003

AbstractThe compatibility of low‐density polyethylene and poly(ethylene‐co‐vinyl acetate) containing 18 wt % vinyl acetate units (EVA‐18) was studied. For this purpose, a series of different blends containing 25, 50, or 75 wt % EVA‐18 were prepared by melt mixing with a single‐screw extruder. For each composition, three different sets of blends were prepared, which corresponded to the three different temperatures used in the metering section and the die of the extruder (140, 160, and 180°C), at a screw rotation speed of 42 rpm. Blends that contained 25 wt % EVA‐18 were also prepared through mixing at 140, 160, or 180°C but at a screw speed of 69 rpm. A study of the blends by differential scanning calorimetry showed that all the prepared blends were heterogeneous, except that containing 75 wt % EVA‐18 and prepared at 180°C. However, because of the high interfacial adhesion, a fine dispersion of the minor component in the polymer matrix was observed for all the studied blends with scanning electron microscopy. The tensile strengths and elongations at break of the blends lay between the corresponding values of the two polymers. The absence of any minimum in the mechanical properties was strong evidence that the two polymers were compatible over the whole range of composition. The thermal shrinkage of the blends at various temperatures depended mainly on the temperature and EVA‐18 content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 841–852, 2003
Determination of polymer–polymer interaction parameters using inverse gas chromatography
Authors: Huang Jan‐Chan 
Published: September 2003

AbstractA modified method is discussed that is based on Farooque and Deshpande's method to obtain polymer–polymer interaction parameters using inverse gas chromatography (IGC) data. In the Farooque and Deshpande method, the ratio of the difference of probe–polymer interaction parameters between two polymers and the probe volume [(χ12 − χ13)/V1] is used as the abscissa. In the modified method, the ratio [(ϕ2χ12 + ϕ3χ13)/V1] is used as the abscissa. Experimental data previously reported for a poly(ϵ‐caprolactone)‐polyepichlorohydrin (PCL/PECH) blend and a poly(ethyl acrylate)‐poly(vinyl propionate) (PEA/PVPr) blend are analyzed. It is found that the slopes obtained by the new method had smaller deviations from the theoretical values than the Farooque and Deshpande method. The standard deviations of both slopes and intercepts obtained from the new method are also smaller. Using the new method, the polymer–polymer interaction parameters obtained from the intercept are negative numbers for the PCL/PECH system and very small positive numbers for PEA/PVPr. Explanations are given for the probe and concentration dependency of the polymer–polymer interaction parameters that are generally observed in IGC studies. A new method for selecting the best probe for calculating the interaction parameter is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 671–680, 2003
Solution spinning and characterization of poly(vinyl alcohol)/soybean protein blend fibers
Authors: Zhang Xiefei , Min Byung G. , Kumar Satish 
Published: September 2003

AbstractSoybean protein/poly(vinyl alcohol) (PVA) blend fibers were processed using wet spinning, after modifying the protein solution by thermal denaturation without alkali. Dynamic mechanical properties as well as scanning electron microscopy studies suggest compatibility between PVA and soybean protein. The effect of crosslinking agent, crosslinking time, and heat‐treatment temperature on the mechanical properties of blend fibers was studied. The soybean protein fibers or the blend fibers containing less than 40% PVA were unoriented amorphous, whereas the blend fibers containing more than 40% PVA exhibited the crystalline structure of PVA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 716–721, 2003
Poly(dimethylsiloxane) coatings for controlled drug release. I. Preparation and characterization of pharmaceutically acceptable materials
Authors: Gao Zongming , Schulze Nahrup Julia , Mark James E. , Sakr Adel 
Published: September 2003

AbstractThe basic technology for forming crosslinked elastomers by the end linking of low molecular weight hydroxyl‐terminated poly(dimethylsiloxane) (PDMS) with tetraethoxysilane (TEOS) was modified to make it suitable for preparing coatings for controlled drug release. The requirements for this application included establishing conditions for the end linking that did not require the usual toxic tin or platinum catalysts; preparation of emulsions of small PDMS network particles that had extensive shelf‐lives and that could be coalesced into cohesive thin films or coatings; and the determination of the conditions to make such coatings pinhole free, mechanically robust, and of sufficient thermal stability for coating procedures at elevated temperatures. The approach taken consisted of preparing water‐based emulsions of the PDMS with sodium lauryl sulfate and restriction of the pH of the system to the acidic range with HCl. Evaporation of water from the emulsions resulted in elastomeric free‐standing films of the PDMS that were characterized using stress–strain isotherms in elongation and equilibrium swelling in toluene, both at room temperature. The mechanical properties of the films were found to improve with an increasing molar ratio of HCl/TEOS and an increase in the amount of TEOS (giving increased degrees of crosslinking). Conditions for the optimization of the thermal stabilities as gauged by thermogravimetic analysis were established, including beneficial effects from the introduction of the crosslinks. Scanning electron microscopy showed that the predominant morphology was void‐free films with very small, homogeneously dispersed silica particles from the hydrolysis of some of the TEOS. Additional work should be facilitated by the mechanisms for the crosslinking suggested by the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 658–666, 2003
Preparation and characterization of alginate hydrogel membranes crosslinked using a water‐soluble carbodiimide
Authors: Xu J. B. , Bartley J. P. , Johnson R. A. 
Published: September 2003

AbstractThe preparation of alginate hydrogel membranes by the film immersion method was optimized for maximum crosslinking using swelling measurements as an indicator of the degree of crosslinking. The variables investigated were the concentration of the nonsolvent (ethanol) for sodium alginate, water‐soluble carbodiimide (WSC) concentration, and pH of the crosslinking medium. Optimum conditions resulted when the crosslinking medium contained 60 vol % ethanol and 100 mM WSC at pH 4. Membranes prepared using different ethanol concentrations (100 mM WSC, pH 4) and different WSC concentrations (60 vol % ethanol, pH 4) were investigated using infrared spectroscopy. The spectra showed the characteristic ester linkage (crosslinking) band at 1698 cm−1 in cases where swelling measurements indicated that crosslinking had occurred. Differential scanning calorimetry of noncrosslinked and crosslinked membranes indicated that crosslinking increased the crystallinity of the membrane. Durability trials showed that membranes crosslinked using the optimum conditions determined in this work retained all weight when immersed in water for 32 days. Membranes prepared using these conditions possessed the characteristics required for use in the pervaporation separation of ethanol–water mixtures. These membranes also have potential as protective coatings for hydrophobic, microporous membranes in the membrane distillation and osmotic distillation concentration of feeds containing surface active components. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 747–753, 2003
Scanning tunnel microscopy study of rayon‐based carbon‐fiber surfaces
Authors: Wu Qi‐Lin , Pan Ding 
Published: September 2003

AbstractBecause of its atomic resolution, scanning tunnel microscopy (STM) was applied to the study of the surface topography, in air, of rayon‐based carbon fibers (RCF) that were not previously studied. By a variety of larger scales, RCF exhibits some rugosities with “peaks” and “valleys.” The surfaces are characterized by stripe‐form crystallite stackings with the diameter of about 10 nm aligned at an angle between 45 and 60° to the fiber axis. A graphitelike structure was first observed on the surface of RCF examined at an atomic resolution scale. Distances between two adjacent carbon atoms of RCF and that between the closest centers of hexagonal carbon rings were estimated. It was also concluded that the hexagonal structure of RCF is deformed graphene (graphitelike) compared with that of highly oriented pyrolytic graphite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 754–758, 2003
Synthesis and characterization of highly branched poly(anhydride‐co‐glycol) with glycerin as branching agent
Authors: Chan Cheng‐Kuang , Chu I‐Ming 
Published: September 2003

AbstractA novel branched poly(anhydride‐co‐glycerol) was synthesized by introducing glycerin into a poly(sebacic anhydride‐co‐ethylene glycol) system via melt condensation without catalyst. The nuclear magnetic resonance spectroscopy (NMR) analysis showed that the reaction between the hydroxyl group on glycerin and the sebacic anhydride pre‐polymer was completed without any hydroxyl group remaining. In addition, with more glycerin introduced, intramolecular chain reaction became more remarkable. This resulted in the production of more cyclic chains and lower molecular weight species that hinder the crystal growth of sebacic anhydride chain segments. This in turn decreases melting temperature of sebacic anhydride chain segments in these synthesized materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 886–893, 2003
Numerical investigation of kinetics of free‐radical polymerization on spinning disk reactor
Authors: Leveson P. , Dunk W. A. E. , Jachuck R. J. 
Published: September 2003

AbstractSpinning disk reactor (SDR) technology has been demonstrated to achieve significant enhancements in free radical polymerization rates. The effect on the rate may be attributed to the unique hydrodynamic environment experienced by the reacting polymer films. The rotating surface of a SDR promotes extension of the polymer chains, which may prevent the propagating chains from terminating through bimolecular reactions. In this article, a numerical simulation is performed to investigate how reduced rates of termination would affect time conversion behavior of free radical initiated styrene polymerization. Comparisons have been made between model predictions and SDR experimental results. The closeness between predicted and experimental results yields strong evidence that the hydrodynamic regime created on the surface of a SDR can lead to reduced rates of bimolecular termination. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 693–699, 2003
A highly selective inhibitor of IκB kinase, BMS‐345541, blocks both joint inflammation and destruction in collagen‐induced arthritis in mice
Authors: McIntyre Kim W. , Shuster David J. , Gillooly Kathleen M. , Dambach Donna M. , Pattoli Mark A. , Lu Pin , Zhou Xia‐Di , Qiu Yuping , Zusi F. Christopher , Burke James R. 
Published: September 2003

AbstractObjectiveThe transcription of several cytokines, cell adhesion molecules, and enzymes involved in the inflammatory and destructive mechanisms of rheumatoid arthritis is dependent on nuclear factor κB (NF‐κB). Because IκB kinase (IKK) is critical in transducing the signal‐inducible activation of NF‐κB, we examined whether the highly selective and orally bioavailable IKK inhibitor BMS‐345541 is efficacious against collagen‐induced arthritis (CIA) in mice.MethodsArthritis in DBA/1LacJ male mice was induced by subcutaneous immunization with bovine type II collagen on day 0 and day 21. BMS‐345541 was administered perorally daily, either prophylactically (before disease onset) or therapeutically (after disease onset). Clinical assessment of the incidence and severity of disease was conducted throughout the study, and histologic evaluation was performed at the time of study termination (day 42).ResultsWhen administered prophylactically, BMS‐345541 (in a dose range of 10–100 mg/kg) was effective, in a dose‐dependent manner, in reducing the incidence of disease and inhibiting clinical signs of disease. Histologic evaluation of the joints showed that both inflammation and joint destruction were blocked by the IKK inhibitor. Message levels of interleukin‐1β in the joints were also dose‐dependently inhibited in the mice that received BMS‐345541. Dose‐dependent efficacy in terms of both disease severity and histologic end points was observed with the therapeutic dosing regimen of BMS‐345541, with use of the 100‐mg/kg dose resulting in resolution of disease.ConclusionIKK plays a key role in CIA in mice, and inhibitors of this enzyme represent a promising target for the development of novel agents to treat rheumatoid arthritis and other inflammatory diseases. BMS‐345541 represents the first example of an inhibitor of IKK that has antiinflammatory activity in vivo.