bluuebunny/crossref_metadata_2025_split huggingface dataset:
Opposite Contribution of Two Ligand-Selective Determinants in the N-Terminal Hormone-Binding Exodomain of Human Gonadotropin Receptors
Authors: Vischer Henry F. , Granneman Joke C. M. , Bogerd Jan 
Published: July 2003

AbstractThe nine leucine-rich repeat-containing exodomains of the human FSH receptor (hFSH-R) and the human LH/chorionic gonadotropin receptor (hLH-R) harbor molecular determinants that allow the mutually exclusive binding of human FSH (hFSH) and human LH (hLH)/human chorionic gonadotropin (hCG) when these hormones are present in physiological concentrations. Previously, we have shown that the β-strands of hLH-R leucine-rich repeats 3 and 6 can confer full hCG/hLH responsiveness and binding when simultaneously introduced into a hFSH-R background without affecting the receptor’s responsiveness to hFSH. In the present study, we have determined the nature of contribution of each of these two β-strands in conferring hCG/hLH responsiveness to this mutant hFSH-R. Human LH-R β-strand 3 appeared to function as a positive hCG/hLH determinant by increasing the hCG/hLH responsiveness of the hFSH-R. In contrast, mutagenesis of hFSH-R β-strand 6, rather than the introduction of its corresponding hLH-R β-strand, appeared to allow the interaction of hCG/hLH with the hFSH-R. Hence, hFSH-R β-strand 6 functions as a negative determinant and, as such, restrains binding of hCG/hLH to the hFSH-R. Detailed mutagenic analysis revealed that the ability of the hFSH-R to interact with hCG/hLH depends primarily on the identity of two amino acids (Asn104, a positive LH-R determinant, and Lys179 a negative FSH-R determinant) that are situated on the C-terminal ends of β-strands 3 and 6, respectively.
Creating aesthetics and functional values in cotton fabrics through the introduction of thermobonding amorphous polyester fibers into blends
Authors: Ghosh Subhas , Villarreal Lila 
Published: July 2003

AbstractLow‐melting thermobonding PET (copolymer) fibers were used to produce heather effects in fabrics blended with cotton, which could be classified as natural 100% cotton fabrics. PET (copolymer) fibers produced at relatively low molecular weights with intrinsic viscosities of 0.57 and 0.47 were used in this investigation. These were mostly amorphous fibers that showed a low specific gravity at 1.27 g cm−3. The fibers were blended with cotton to produce open‐ended spun yarns without the PET component being melted. These yarns were knit into fabrics and cured. The curing was based on the thermal behavior of these fibers as observed in differential scanning calorimetry thermograms. The amount of pigmented PET copolymer needed to achieve the required heather effect was optimized by variations of the blend ratios. This approach provided another avenue for introducing additional functional properties, such as antibacterial and soil‐resistance properties, to the fabric. Both the fibers and resultant fabric properties were studied extensively, along with the finishing of these fabrics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3747–3756, 2003
Preparation and characterization of siliconized epoxy‐1,2‐bis(maleimido)ethane intercrosslinked matrix materials
Authors: Kumar A. Ashok , Dinakaran K. , Alagar M. 
Published: July 2003

AbstractNovel intercrosslinked networks of siliconized epoxy‐1,2‐bis(maleimido)ethane matrix systems are developed. The siliconization of epoxy resin is carried out by using 5–15% hydroxyl‐terminated poly(dimethylsiloxane) with γ‐aminopropyltriethoxysilane as a crosslinking agent and dibutyltin dilaurate as a catalyst. The siliconized epoxy systems are further modified with 5–15% 1,2‐bis(maleimido)ethane and cured by using diaminodiphenylmethane. The prepared neat resin castings are characterized for their mechanical properties. Mechanical studies indicate that the introduction of siloxane into these epoxy resins improves the toughness with a reduction in the stress–strain values, whereas incorporation of bismaleimide (BMI) into the epoxy resin improves the stress–strain properties with a lowering of the toughness. The introduction of both siloxane and BMI into the epoxy resin influences the mechanical properties according to their content percentages. Differential scanning calorimetry (DSC), thermogravimetry, and heat distortion temperature analyses are also carried out to assess the thermal behavior of the matrix materials that are developed. DSC thermograms of the BMI modified epoxy systems show unimodal reaction exotherms. The glass‐transition temperature, thermal degradation temperature, and heat distortion temperature of the cured BMI modified epoxy and siliconized epoxy systems increase with increasing BMI content. The water absorption behavior of the matrix materials is also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3808–3817, 2003
Preparation of molecularly imprinted Fe3O4/P(St‐DVB) composite beads with magnetic susceptibility and their characteristics of molecular recognition for amino acid
Authors: Lu Shulai , Cheng Guoxiang , Pang Xingshou 
Published: July 2003

AbstractTyrosine and phenylalanine imprinted Fe3O4/P(St‐DVB) composite beads with magnetic susceptibility were prepared by suspension polymerization using Fe3O4 as the magnetically susceptible component, methacrylic acid and acrylamide as functional monomers, styrene and divinylbenzene as polymeric matrix components, stearic acid as porogen, and poly(ethylene glycol) 4000 as dispersant. Scanning electron microscopy examination of the composite beads showed macropores on the surface of spherical beads. The diameters of the composite beads and the macropores were in the ranges ∼ 400–450 and 4–20 μm, respectively. The average content of Fe3O4 inside the composite beads was 3.78%, and Fe3O4 was unevenly distributed. The mechanism of macropore formation and the concept of “intellectual cavity” of molecularly imprinted composite beads were proposed. The recognition selectivity of the composite beads was investigated using tyrosine and phenylalanine as both templates and comparative molecules. Tyrosine‐imprinted composite beads exhibited a good recognition selectivity for tyrosine, and the separation factor was up to 3.67. In contrast, phenylalanine‐imprinted composite beads had little recognition selectivity for phenylalanine and the separation factor was only 1.12. It was confirmed that the three‐site interaction between tyrosine and functional monomers was stronger than the two‐site interaction between phenylalanine and functional monomers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3790–3796, 2003
Effect of fillers on curing of wood surfaces with polyester oligomers by ultraviolet radiation
Authors: Beg M. D. H. , Khan Mubarak A. , Abedin M. Z. 
Published: July 2003

AbstractA set of formulations was prepared with polyester acrylate (oligoester M‐9050) oligomers in combination with reactive diluents of different functionalities such as ethylhexyl acrylate, tripropylene glycol diacrylate , and trimethylol propane triacrylate (TMPTA). The thin films were prepared with these formulated solutions under UV radiation on a glass plate, and their physical properties such as pendulum hardness and gel content were studied. The formulation containing TMPTA showed the greatest pendulum hardness and gel content. The polished wood surfaces were cured with these formulated solutions. Physical properties such as pendulum hardness gloss at 20° and 60° angles, adhesion, abrasion resistance, and scratch hardness of UV‐cured surfaces of the wood were characterized. The formulation containing TMPTA had the best physical properties. Two types of filler, sand and talc, were used in the base coat to obtain these better properties. Both fillers improved the properties; however, the 1% sand– and 4% talc–containing formulations performed better. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3826–3834, 2003
Lifetime prediction of the epoxy system DGEBA (n = 0)/1,2‐DCH modified with an epoxy reactive diluent by thermogravimetric analysis
Authors: Núñez Lisardo , Villanueva M. , Núñez M. R. , Rial B. 
Published: July 2003

AbstractThermogravimetric analysis was used to predict the lifetime of two three‐component systems of diglycidyl ether of bisphenol A (n = 0)/1,2‐diamine cyclohexane [DGEBA (n = 0)/1,2‐DCH] modified with different concentrations of an epoxy reactive diluent, vinylcyclohexene dioxide (VCHD). Experimental results were treated using two methods. The first method was independent of the degradation mechanism, and the second was based on the thermodegradation kinetic mechanism. The activation energies of the reaction were determined using the Flynn–Wall–Ozawa method. These values were compared with those obtained using Kissinger's method. From experimental results it was found that the optimum temperature of service for these materials were different, so one or the other must be selected, depending on the application temperature considered. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3835–3839, 2003
Structure and properties of nitrile rubber (NBR)–clay nanocomposites by co‐coagulating NBR latex and clay aqueous suspension
Authors: Wu You‐Ping , Jia Qing‐Xiu , Yu Ding‐Sheng , Zhang Li‐Qun 
Published: July 2003

AbstractNitrile rubber (NBR)–clay nanocomposites were prepared by co‐coagulating the NBR latex and clay aqueous suspension. Transmission electron microscopy showed that the silicate layers of clay were dispersed in the NBR matrix at the nano level and had a planar orientation. X‐ray diffraction indicated that there were some nonexfoliated silicate layers in the NBR–clay nanocomposites. Stress–strain curves showed that the silicate layers generated evident reinforcement, modulus, and tensile strength of the NBR–clay nanocomposites, which were significantly improved with an increase in the amount of clay, and strain‐at‐break was higher than that of the gum NBR vulcanizate when the amount of clay was more than 5 phr. The NBR–clay nanocomposites exhibited an excellent gas barrier property; the reduction in gas permeability in the NBR–clay nanocomposites can be described by Nielsen's model. Compared with gum NBR vulcanizate, the oxygen index of the NBR–clay nanocomposites increased slightly. The feasibility of controlling rubber flammability via the nanocomposite approach needs to be evaluated further. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3855–3858, 2003
Dimensional stability of oriented, rigid poly(vinyl chloride)
Authors: Hitt David J. , Gilbert Marianne 
Published: July 2003

AbstractOriented PVC has enhanced properties, but on heating it begins to shrink and eventually reverts to its original dimensions. Thermomechanical analysis was used to study the effects of orientation variables and subsequent annealing or aging on the shrinkage of rigid PVC. The thermal history of the oriented PVC affected its crystallinity and the free volume in the oriented structure. These changes modified the temperature at which the oriented samples began to shrink (i.e., their dimensional stability.) Higher draw and annealing temperatures can be used to improve dimensional stability; however, their effective use is limited because PVC has a peak elongation at 90°C. Increased annealing time also increases dimensional stability. Aging greatly improves the dimensional stability of the material; this process can be accelerated at temperatures up to 60°C. The shrinkage onset temperature can be increased without compromising the enhancement of mechanical properties achieved by orientation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3859–3867, 2003
Modeling of moisture sorption isotherms of poly(vinyl alcohol)/starch films
Authors: Raj Baldev , Eugene Raj A. , Madan P. , Siddaramaiah  
Published: July 2003

AbstractStudies on the moisture sorption characteristics of poly(vinyl alcohol)/starch blends for water activity (aw) values of 0.1–0.9 were performed at 27°C. The equilibrium moisture content at different aw values was used to fit different sorption isotherm models proposed in the literature. The ranges of aw applicable for the different sorption isotherms were reported. The model constants of the sorption equations were determined by linear fitting. The value of the coefficient of determination (0.98 ± 0.01) confirmed the goodness of fit of the equations studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3874–3881, 2003
Fe2+ and Fe3+ adsorption on 2‐vinylpyridine–divinylbenzene copolymers and acrylonitrile–methyl methacrylate–divinylbenzene terpolymers
Authors: Rabelo D. , Silva V. J. , Alcântara E. F. C. , Faria L. C. , Martins G. A. V. , Garg V. K. , Oliveira A. C. , Morais P. C. 
Published: July 2003

AbstractThe adsorption of Fe2+ and Fe3+ ions on 2‐vinylpyridine–divinylbenzene copolymer and acrylonitrile–methyl methacrylate–divinylbenzene terpolymer was investigated. In general, the adsorption of Fe2+ and Fe3+ in both resins increased with the enhancement of hydrochloric acid and metal concentration. The metal adsorption on the terpolymer increased sharply with the addition of small portions of ethanol, whereas the adsorption on the copolymer practically was not affected by the presence of the alcohol. An increase in temperature produced a small increase in iron adsorption for both resins. Fourier transform infrared spectra showed that nitrile and ester groups of the terpolymer did not suffer hydrolysis during metal adsorption, even for the highest HCl concentration and the highest temperature applied. A mechanism of iron adsorption through the ion exchange of chloride anions by tetrahedral [FeCl4]2− or [FeCl4]− anions is proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3905–3912, 2003
Preparation and the properties of PMR‐type polyimide composites with aluminum nitride
Authors: Wang Jiajun , Yi Xiao‐Su 
Published: July 2003

AbstractA new polyimide composite was developed relying on the concept of in situ polymerization of monomer reactants polyimide. High thermal conductive, low dielectric constant and dielectric loss, and thermal‐stable composites were successfully demonstrated by incorporating aluminum nitride powder into the polyimide. The weight percent of aluminum nitride was up to 80%. The thermal and dielectric properties follow the classic composite theories. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3913–3917, 2003
The study of polymerization kinetics of methacrylamide by oxidation: Reduction system using potassium permanganate/glycine in aqueous medium
Authors: Mirzaei A. A. , Shaterian H. R. , Habibi S. M. 
Published: July 2003

AbstractThe polymerization kinetic of methacrylamide with the KMnO4/glycine redox system has been investigated volumetrically at 35±0.1°C under nitrogen atmosphere in aqueous sulfuric acid medium in a dimethylsulfoxide/H2O mixture (5% v/v). The rates of polymerization were found to obey the following equation: Rp ∝ [Methacrylamide]1.08[Glycine]0.44[KMnO]0.46. A glycine end group containing polymethacrylamide was prepared by the MnO/glycine redox system under mild conditions. The reaction proceeded with radical mechanism and the overall energy of activation (Ea) was calculated to be 29.87 kJ/mol from the Arrhenius plot in the temperature range 25–50°C. Molecular weight of the polymer was determined by viscometry. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3918–3924, 2003
Theoretical evaluation and the effect of thermal degradation on the Time–Temperature–Transformation (TTT) diagram of bisphenol A epoxies
Authors: Stutz Herbert 
Published: July 2003

AbstractA brief discussion about the Time–Temperature–Transformation (TTT) diagram is presented. Using diamino diphenylsulfone‐cured diglycidyl bisphenol A as a representative example, its TTT diagram is completed by including the thermal degradation. The theoretical diagram as obtained from the kinetics of curing and thermal degradation is compared with experimental data. The agreement is good, slight deviations are observed only in the time to vitrify above 150°C and the maximum available glass temperature, which is due to side reactions and onset of thermal degradation during curing. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3894–3896, 2003
Studies on acrylic acid–grafted polyester fabrics by electron beam preirradiation method. II. Novel intelligent immersion‐resistant and moisture‐permeable fabrics
Authors: He Changcheng , Gu Zhenya , Tian Junying 
Published: July 2003

AbstractMoisture regain, water vapor permeability, and water‐impermeable ability of polyester fabrics before and after grafting by acrylic acid (AA) were investigated. The results showed that the AA‐grafted fabric presents novel properties. When it is dry it possesses a higher water vapor transmission rate. Once it comes into contact with water, the grafted poly(acrylic acid) layer on the fibers' surface begins to swell and seals the intervals between fibers and yarns to prevent water from penetrating, a phenomenon known as immersion resistance. This kind of immersion‐resistant and moisture‐permeable fabrics might be a suitable candidate for the immersion‐resistant layer fabrics of Type B immersion‐resistant suits. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3939–3943, 2003
Porous cellulose acetate membrane prepared by thermally induced phase separation
Authors: Matsuyama Hideto , Ohga Kazuhiro , Maki Taisuke , Tearamoto Masaaki , Nakatsuka Shuji 
Published: July 2003

AbstractMicroporous cellulose acetate membranes were prepared by a thermally induced phase separation (TIPS) process. Two kinds of cellulose acetate with acetyl content of 51 and 55 mol % and two kinds of diluents, such as 2‐methyl‐2,4‐pentandiol and 2‐ethyl‐1,3‐hexanediol, were used. In all polymer‐diluent systems, cloud points were observed, which indicated that liquid–liquid phase separation occurred during the TIPS process. The growth of droplets formed after the phase separation was followed using three cooling conditions. The obtained pore structure was isotropic, that is, the pore size did not vary across the membrane. In addition, no macrovoids were formed. These pore structures were in contrast with those usually obtained by the immersion precipitation method. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3951–3955, 2003
Socioeconomic effects on the risk of having a recognized pregnancy with Down syndrome
Authors: Torfs Claudine P. , Christianson Roberta E. 
Published: July 2003

AbstractBACKGROUNDAppoximately 95% of Down syndrome (DS) cases are caused by an error in germ cell division (meiosis), resulting in an extra chromosome 21. The meiotic error, predominantly of maternal origin, occurs either during the mother's fetal life (meiosis I) or at ovulation (meiosis II). Because maternal‐age‐specific DS prevalence rates vary between and within populations, it has been hypothesized that environmental factors can affect the risk for a DS pregnancy.METHODSIn a population‐based case‐control study of 997 clinically recognized DS cases (including fetal losses) and 1007 controls without a birth defect, we examined the mother's socioeconomic status (SES) from the time of her fetal life to the time of conception. SES variables were considered as proxies for environmental factors. We used multiple logistic regression for the analyses.RESULTSWe found associations with low levels of each SES variable examined: mother's education less than high school (OR, 1.29; 95% CI, 1.01–1.65), father's low occupation (OR, 1.23; 95% CI, 0.95–1.60), father's low education (OR, 1.28; 95% CI, 0.99–1.64), mother's father's low occupation (OR, 1.35; 95% CI, 1.06–1.71), and family income $820,000 (OR, 1.31; 95% CI, 1.02–1.68). The risk for DS increased as the number of low socioeconomic factors present throughout the mother's life increased. With four factors present, the risk (adjusted for confounders) almost doubled (OR, 1.98; 95% CI, 1.30–3.01). Those associations persisted among young (<30) and old (≥30) maternal age groups.CONCLUSIONSA mother's low SES during any period before conception increases her risk for a recognized pregnancy with DS. Because of the high birth prevalence of DS, the public health impact of maternal SES may be considerable. Birth Defects Research (Part A) 67:522–528, 2003. © 2003 Wiley‐Liss, Inc.
Trichloroethylene effects on gene expression during cardiac development
Authors: Collier J. Michael , Selmin Ornella , Johnson Paula D. , Runyan Raymond B. 
Published: July 2003

AbstractBACKGROUNDHalogenated hydrocarbon exposure is associated with changes in gene expression in adult and embryonic tissue. Our study was undertaken to identify differentially expressed mRNA transcripts in embryonic hearts from Sprague‐Dawley rats exposed to trichloroethylene (TCE) or potential bio‐transformation products dichloroethylene (DCE) and trichloroacetic acid (TCAA).METHODScDNA subtractive hybridization was used to selectively amplify expressed mRNA obtained from control or halogenated hydrocarbon exposed rat embryos. The doses used were 1100 and 110 ppm (8300 and 830 μM) TCE, 110 and 11 ppm (1100 and 110 μM) DCE, and 27.3 and 2.75 mg/ml (100 and 10 mM) TCAA. Control animals were given distilled drinking water throughout the period of experiments.RESULTSSequencing of over 100 clones derived from halogenated hydrocarbon exposed groups resulted in identification of numerous differentially regulated gene sequences. Up‐regulated transcripts identified include genes associated with stress response (Hsp 70) and homeostasis (several ribosomal proteins). Down‐regulated transcripts include extracellular matrix components (GPI‐p137 and vimentin) and Ca2+ responsive proteins (Serca‐2 Ca2+‐ATPase and β‐catenin). Two possible markers for fetal TCE exposure were identified: Serca‐2 Ca2+‐ATPase and GPI‐p137, a GPI‐linked protein of unknown function. Differential regulation of expression of both markers by TCE was confirmed by dot blot analysis and semi‐quantitative RT‐PCR with levels of TCE exposure between 100 and 250 ppb (0.76 and 1.9 μM) sufficient to decrease expression.CONCLUSIONSSequences down‐regulated with TCE exposure appear to be those associated with cellular housekeeping, cell adhesion, and developmental processes, while TCE exposure up‐regulates expression of numerous stress response and homeostatic genes. Birth Defects Research (Part A) 67488–495, 2003. © 2003 Wiley‐Liss, Inc.