bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microporous membranes prepared from blends of polysulfone and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide)
Authors: Schauer Jan , Albrecht Wolfgang , Weigel Thomas , Kůdela Vlastimil , Pientka Zbynek 
Published: August 2002

AbstractMembranes were prepared from solutions containing Udel‐type polysulfone (PSf) and sulfonated poly(2,6‐dimethyl‐1,4‐phenylene oxide) (SPPO). Polymer solutions in 1‐methyl‐2‐pyrrolidone were cast on a nonwoven textile and precipitated in a water bath. The permeabilities and selectivities of the prepared membranes depended on the concentrations of both polymers in the casting solution. The higher the concentration of PSf, the lower were the permeabilities to water and average pore sizes of the membranes. On the other hand, a very small amount of SPPO in the casting solution (about 1–4 wt % relative to the casting solution weight) brought about a considerable increase in water permeabilities and had a small influence on the average pore sizes. The effects were most pronounced if SPPO with a degree of sulfonation of 20–40% was used. The considerable increase in water permeabilities was explained by separation of the PSf and SPPO phases during precipitation in water and by the concentration of hydrophilic SPPO on the surface of the membrane and its pores. The determinations of the oriented concentration potentials proved the presence of a negative surface charge in the membranes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 134–142, 2001
Orientational effect of mica in fumed silica reinforced composites
Authors: Bokobza L. , Nugay N. 
Published: August 2002

AbstractInfrared and birefringence measurements are used to characterize the orientational behavior of fumed silica and mica hybrid‐reinforced poly(dimethylsiloxane) composites. Results of equilibrium stress–strain and swelling experiments are also reported and correlated with the orientational data. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 215–222, 2001
Nanoparticles carrying hydroxyl groups produced by microemulsion
Authors: Özer F. , Beşkardeş M. O. , Zareie H. , Pi̇şki̇n E. 
Published: August 2002

AbstractMethylmethacrylate and 2‐hydroxyethylmethacrylate were polymerized in oil‐in‐water microemulsions that were stabilized by cetyltrimetylammonium bromide (CTAB). Microemulsions that prepared changed continuously from transparent microemulsions to turbid emulsions by increasing the HEMA weight percentage as a comonomer. Polymerization was initiated with an oil‐soluble initiator, azobisizobutyronitrile (AIBN). Stable P(MMA‐HEMA) latexes were obtained about 40 nm in diameter. Molecular weights of the copolymers were in the range of 1.89–2.03 × 106. The glass transition temperatures of these copolymers, which were obtained by differential scanning calorimeter, were in the range of 95–99°C. The comonomer ratio in the final copolymers were obtained from the nuclear magnetic resonance spectra, which were smaller than the comonomer ratios used in the original recipes. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 237–242, 2001
Polymerization of benzoguanamine and pyromellitic dianhydride under microwave radiation and its third‐order optical nonlinearities
Authors: Lu Jianmei , Chen Naiyong , Ji Shunjun , Sun Zhenrong , Ding Meixiang , Zhu Xinlin 
Published: August 2002

AbstractPolycondensation and imidization of benzoguanamine and pyromellitic dianhydride under microwave radiation were studied. The effects of the microwave radiation time (power), the composition of the monomer on the imidization, and the polymer yield were discussed. The polycondensates' third‐order optical nonlinearities and time responses were measured by a phase conjugate forward, 3‐dimensional degenerate, four‐wave mixing technique. At the same time they were compared with relevant conventional thermopolymerization. The results showed that the polycondensates had high third‐order nonlinear optical coefficients [polyimide (PI) χ(3) = 1.181 × 10−13 esu] and fast time responses (22 ps). The third‐order nonlinear optical coefficients under microwave radiation were higher than that of conventional thermopolymerization (microwave radiation PI χ(3) = 1.181 × 10−13 esu: thermopolymerization PI χ(3) = 0.686 × 10−13 esu). The experimental results also showed that the third‐order optical nonlinearities were not only affected by the length of the polycondensate chain, but also the polycondensate π‐electron density distribution, which was explained and confirmed by computation with the semiempirical Austin method. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1356–1363, 2001
Photolysis of poly(benzyl methacrylate)s and poly(benzyl acrylate)s in solution and films
Authors: Itoh Yoshihiro , Goshima Toshiyuki , Shirai Hirofusa 
Published: August 2002

AbstractMethacrylate and acrylate copolymers containing benzyl or 1‐phenylethyl groups and their monomeric model compounds were irradiated with a 254‐nm light in CH2Cl2 and solid films. Low molecular weight and polymeric products were analyzed by gas chromatography (GC) and NMR spectroscopy, respectively, and main‐chain scission efficiencies were determined by gel permeation chromatography (GPC). The results indicate that the ester bond cleavage in the side chain produces alkyl radicals in the main chain, leading to main‐chain scission and crosslinking. The higher stability of tertiary alkyl radicals formed in methacrylate polymers lead to the predominant main‐chain scission in solution. On the other hand, acrylate polymers were less susceptible to photodegradation. The degradabilities of the polymer films reflected those of the polymer solutions, although crosslinking preferentially occurred. The distinct effect of oxygen on the degradation was also observed in solution and films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2227–2236, 2001
Polymer–inorganic nanocomposites prepared by hydrothermal method: Preparation and characterization of PVA–transition‐metal sulfides
Authors: Qian X. F. , Yin J. , Yang Y. F. , Lu Q. H. , Zhu Z. K. , Lu J. 
Published: August 2002

AbstractNanocomposites of poly(vinyl alcohol) (PVA) with iron, cobalt, or nickel sulfides were successfully prepared using a hydrothermal process by an in situ reaction with CS2 at 140°C for 8 h. XRD results showed that pure phases of FeS2, CoS2, and NiS were obtained in the as‐prepared nanocomposites. They also showed that the crystallinity of PVA was largely decreased after incorporation of the nano‐sized sulfides. This was also confirmed by IR spectroscopy. SEM photographs showed that the sulfide particles were homogeneously dispersed in the PVA matrix. UV‐visible spectroscopy was also used to characterize the as‐prepared nanocomposites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2744–2749, 2001
Flow behavior of polyacrylamide solution. III. Mathematical treatment
Authors: Yang Mu‐Hoe 
Published: August 2002

AbstractThe flow behavior of polyacrylamide solutions was systematically determined over a wide range of temperatures (20–50°C) and concentrations (20–50 ppm) by using a coaxial cylinder viscometer. The results indicated that the rheological behavior of low‐concentration polyacrylamide solution behaves similar to non‐Newtonian fluids at all these concentrations. The effect of temperature on the consistency coefficient and flow behavior index of polyacrylamide solution of the different concentrations followed an Arrhenius‐type relationship. Moreover, the effect of concentration on consistency coefficient and flow behavior index followed an exponential‐law relationship at the temperatures used. The rheological constants for the Arrhenius and exponential‐law models were determined. The combined effect of temperature and concentration on the coefficient of dynamic shear stress can be represented by a single equation: shear stress = 2.446 × 10−7exp(0.0639C + 3613/RT)(shear rate)2.337 exp(−0.00707C−245/RT). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2784–2789, 2001
The dynamic adsorption of benzene vapor on the ACF activated by phosphoric acid
Authors: Fu Ruowen , Liu Ling , Zeng Hanmin 
Published: August 2002

AbstractThe dynamic adsorption behaviors of benzene vapor on phosphoric acid‐activated carbon fiber (ACF‐P) were investigated by gas chromatography. The experimental results showed that ACF‐P that was activated at >350°C, like steam‐activated carbon fiber (ACF‐W), has good dynamic adsorption properties for benzene vapor. However, the saturation adsorption capacities of ACF‐P and ACF‐W are different. The dynamic adsorption conditions apparently do not affect the effluent concentration before the breakthrough point, but do change the operation loading and usage efficiency. The adsorbed ACF‐P can be regenerated, and good dynamic adsorbability can be recovered by heating treatment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1841–1847, 2002
A review of littoral tourism, sport and leisure activities: consequences on marine flora and fauna
Authors: Bellan Gerard L. , Bellan‐Santini Denise R. 
Published: August 2002

Abstract1. A report on the scientific aspects of the consequences of tourism and other leisure activities on the marine flora and fauna has been prepared on behalf of the French Ministry of the Environment. This involved an exhaustive bibliographical review resulting in a series of proposals to address some of the issues highlighted.2. Our knowledge is too often based on observations of the deeds and misdeeds of tourism along with only a small amount of experimental study.3. The main proposals are that there should be: (1) a compilation of all studies ordered by and for the State and its decentralized services, local communities and private companies; (2) definition of priority species and ecosystems; (3) observations on the direct and indirect impacts by tourists and sportsmen on the natural environment for each one of the large biotopes; (4) quantification of the impact of recreational fishing; (5) an integration of biological, sociological, economic and judicial disciplines in the management of the marine environment. Copyright © 2001 John Wiley & Sons, Ltd.
Calnexin is associated with and induced by overexpressed human complement protein C2
Authors: Tsukamoto Hiroshi , Tousson Albert , Circolo Antonella , Marchase Richard B. , Volanakis John E. 
Published: August 2002

AbstractC2 is a serum glycoprotein that is essential for activation of the classical and lectin pathways of the complement system. We reported previously that in transiently transfected COS cells, C2 accumulates in the endoplasmic reticulum‐Golgi intermediate compartment (ERGIC). Transfection with a cDNA corresponding to a variant C2 mRNA in which exon 17 is spliced out, C2Δ(17), resulted in retention of the mutant polypeptide in the ER. We now show that calnexin, a lectin‐like chaperone, colocalizes with wild‐type (wt) C2 and C2Δ(17). Biosynthetic labeling and sequential immunoprecipitation experiments indicated that colocalization is due to a physical association between calnexin and C2. Immunofluorescence analysis indicated that calnexin was upregulated in cells transfected with either C2 species. Upregulation of calnexin was not affected by castanospermine, which inhibits glucosidases I and II. However, castanospermine inhibited translocation of calnexin to the ERGIC in wt C2 transfected cells. Upregulation of calnexin was also observed in cells transfected with the complement protein factor B, a glycoprotein with extensive structural and functional similarities to C2, but not in cells transfected with complement proteins C3 or factor D, which have no structural similarity to C2, and low or no glycan content, respectively. Calnexin upregulation by transfection with C2 or factor B, but not factor D, was also demonstrated by quantitative analysis of calnexin immunoprecipitates from biosynthetically labeled cells. Increased calnexin expression by overexpressed C2 and factor B appears to be triggered either by the high glycan content of these proteins or, since it also occurs in the presence of castanospermine, by shared features of the structure of these two proteins. Anat Rec 267:7–16, 2002. © 2002 Wiley‐Liss, Inc.
Cholinergic and noncholinergic innervation of the smooth muscle layers in the bovine abomasum
Authors: Pfannkuche Helga , Reiche Dania , Hoppe Susanne , Schemann Michael 
Published: August 2002

AbstractThe intrinsic innervation of muscle layers in the mammalian gastrointestinal tract has been mainly studied in nonruminants. The aim of this study was to identify intrinsic motor neurones in the bovine abomasum that innervate the circular and longitudinal muscles. Circular (CMN) and longitudinal muscle motor neurones (LMN) were selectively labeled by application of the retrograde tracer 1,1′‐didodecyl‐3,3,3′,3′‐tetramethyl indocarbocyanine perchlorate (DiI) onto the muscle layers. The transmitter phenotype was determined by immunohistochemical detection of choline acetyltransferase (ChAT), nitric oxide synthase (NOS), and neurone‐specific enolase (NSE). On average, the myenteric ganglia contained 61 ± 19 NSE‐positive cell bodies, of which 89% were ChAT‐positive and 10% were NOS‐positive. Only 0.7% of NSE‐positive neurones (41 of 5,777) contained both ChAT and NOS. Application of DiI onto the circular and longitudinal muscles revealed on average 60 ± 27 (n = 4) and 68 ± 36 (n = 4), respectively, labeled cell bodies in the myenteric plexus. For the circular and longitudinal muscles the proportions of ascending to descending neurones were 76 : 24% and 54 : 46%, respectively. While most ascending CMN were ChAT‐positive (96%), 51% of the descending CMN were ChAT‐negative. All ascending and 95% of descending LMN were ChAT‐positive. It was concluded that cholinergic excitatory innervation is predominant in both muscle layers of the abomasum. Whereas the circular muscle receives cholinergic excitatory and nitrergic inhibitory innervation, the longitudinal muscle is only innervated by cholinergic pathways. This innervation pattern is different from that in gastric muscle layers in monogastric animals. Anat Rec 267:70–77, 2002. © 2002 Wiley‐Liss, Inc.
Substituent‐dependent, positive and negative modulation of Bombyx mori adenylate cyclase by synthetic octopamine/tyramine analogues
Authors: Aoyama Masato , Nakane Toshiya , Ono Takako , Khan Md. Anwar Arfien , Ohta Hiroto , Ozoe Yoshihisa 
Published: August 2002

AbstractOctopamine (OCT)/tyramine (TYR) analogues, mainly including p‐ and β‐substituted phenylethylamines, were prepared as probes for the ligand‐binding site(s) of adenylate cyclase‐coupled OCT or TYR receptors, and were examined for their effects on cAMP production in the head membranes of Bombyx mori larvae. Small structural changes in OCT and TYR proved to lead to three types of OCT/TYR analogues: (1) compounds that increase the cAMP level by themselves and also depress OCT‐stimulated cAMP production, (2) compounds that do not stimulate cAMP production by themselves but inhibit OCT‐stimulated cAMP production, and (3) compounds that are not active in either the stimulation of cAMP production or the inhibition of OCT‐stimulated cAMP production. Tyramine, which belongs to the second group, also inhibited the basal level of cAMP production at high concentrations. The data indicate that two biogenic amine systems that positively and negatively regulate the level of the second messenger cAMP are present in the head part of B. mori larvae. This finding points to the necessity of separately evaluating the positive and negative regulatory effects in order to quantitatively understand the structure‐activity relationships of OCT receptor ligands. Arch. Insect Biochem. Physiol. 47:1–7, 2001. © 2001 Wiley‐Liss, Inc.
Sampling and concentration values of incomplete bibliographies
Authors: Egghe L. 
Published: August 2002

AbstractThis article studies concentration aspects of bibliographies. More, in particular, we study the impact of incompleteness of such a bibliography on its concentration values (i.e., its degree of inequality of production of its sources). Incompleteness is modeled by sampling in the complete bibliography. The model is general enough to comprise truncation of a bibliography as well as a systematic sample on sources or items. In all cases we prove that the sampled bibliography (or incomplete one) has a higher concentration value than the complete one. These models, hence, shed some light on the measurement of production inequality in incomplete bibliographies.
An analysis of Taguchi's on‐line quality monitoring procedure for attributes with diagnosis errors
Authors: Borges Wagner , Ho Linda Lee , Turnes Osiris 
Published: August 2002

AbstractThe on‐line quality monitoring procedure for attributes proposed by Taguchi, Elsayed and Hsiang for processes in which the fraction defective shifts from 0 at some point are examined under the assumption of diagnosis errors. The renewal reward (economic) approach of Nayebpour and Woodall is used to develop a mathematical expression for the long‐run expected cost per item produced and assessment of the optimum inspection interval is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Stereoselective metabolism and pharmacokinetics of tegafur
Authors: Damle Bharat D. , Narasimhan Narayana I. , Kaul Sanjeev 
Published: August 2002

AbstractObjectives. UFT is composed of racemic tegafur (FT), a prodrug of 5‐fluorouracil (5‐FU), and uracil in a fixed molar combination (1:4). FT contains a chiral center and has two stereoisomers, R‐FT and S‐FT. The objectives of this study were to assess the stereoselectivity in the metabolism of FT to 5‐FU in vitro and to determine stereoselective differences in the disposition of FT in vivo.Methodology. R‐FT, S‐FT, and racemic FT were incubated with pooled human liver microsomes and S‐9 fraction for a period of up to 30 min for in vitro studies. For pharmacokinetics, plasma samples were obtained from fasted cancer patients over a period of 24 h after oral administration of 200 mg UFT. Samples from in vitro studies and patient plasma samples were analyzed for FT using a validated achiral and a chiral assay, and for 5‐FU using a validated GC/MS assay.Results. R‐FT was metabolized at a rate 5.6‐times faster than S‐FT by human liver microsomes. Similarly, stereoselective metabolism of R‐FT was also seen in the S‐9 incubations. In cancer patients, the peak plasma concentrations (Cmax) and the time to reach Cmax (Tmax) were similar for the two isomers after the administration of UFT suggesting no apparent differences in their absorption kinetics. However, the area under the curve from zero to infinity [AUC(INF)] and the terminal elimination half‐life (T‐HALF) values for R‐FT were about 4.6‐ and 4.4‐fold lower compared to S‐FT, respectively, suggesting the preferential elimination of R‐FT. The T‐HALF of racemic FT (8.3 h) was comparable to the T‐HALF of S‐FT (10.3 h) which indicated that the kinetics of the racemate are governed by S‐FT. The active cytotoxic moiety, 5‐FU, exhibited formation rate limited kinetics from R‐FT because the T‐HALF of 5‐FU (3.4 h) was similar to that of R‐FT (2.4 h).Conclusions. The R‐isomer of FT is preferentially metabolized to 5‐FU compared to the S‐isomer in vitro. The distinct kinetic profiles of the stereoisomers of FT following the administration of UFT is apparently due to the stereoselective disposition of the R‐isomer relative to the S‐isomer. These data suggest that the R‐isomer of FT is worthy of further preclinical and clinical evaluation for safety, efficacy, and pharmacokinetics. Copyright © 2001 John Wiley & Sons, Ltd.
The pharmacokinetics of ethosuximide enantiomers in the rat
Authors: Mifsud J. , Collier P.S. , Millership J.S. 
Published: August 2002

AbstractA chiral gas chromatographic assay previously developed for quantitative analysis of ethosuximide and its major metabolites in rat urine has been adapted for the analysis of the drug in plasma. Ethosuximide, both as a racemic mixture and as the individual enantiomers, was administered to conscious rats by the intravenous (i.v.) and intraperitoneal (i.p.) routes. Pharmacokinetic parameters were estimated using standard non‐compartmental methods. Comparison of the pharmacokinetic parameters of (S)‐ethosuximide and (R)‐ethosuximide showed that total body clearance of (R)‐ethosuximide was significantly larger than that of (S)‐ethosuximide and that elimination half‐life was significantly shorter following administration of both 40 mg i.v. and i.p. doses, indicating that there is stereoselective elimination of ethosuximide. However, no significant differences were found between apparent volumes of distribution. In addition, no significant differences were found for either enantiomer between the estimates of the pharmacokinetic parameters obtained following administration as the individual enantiomer and as a constituent of the racemic mixture. This indicates that, at the doses studied, the preferential faster elimination of (R)‐ethosuximide is not dependent upon the presence of the (S)‐enantiomer. Also, for each enantiomer, the lack of any significant difference between estimates of clearance when administered as part of a racemic mixture and when administered separately indicates that neither enantiomer affects the clearance of the other. Copyright © 2001 John Wiley & Sons, Ltd.
Why biologists should support the exploration of Mars
Authors: Maurel Marie‐Christine , Zaccai Giuseppe 
Published: August 2002

AbstractPhysicists, chemists and geologists in the USA and Europe propose that the search for extraterrestrial life is an important justification for the exploration of Mars. Biologists, however, much more excited by the advent of the postgenome sequencing era, in general display little enthusiasm for planetary exploration. We argue that the search for traces of life on Mars represents a major thought‐provoking challenge for the life sciences that should be taken up by the biological community. BioEssays 23:977–978, 2001. © 2001 John Wiley & Sons, Inc.
Quantitative analysis of the regulation scheme of invertase expression in Saccharomyces cerevisiae
Authors: Herwig Christoph , Doerries Christos , Marison Ian , von Stockar Urs 
Published: August 2002

AbstractIn Saccharomyces cerevisiae, the expression of invertase, which is the hydrolyzing enzyme of sucrose, is controlled by the presence of monosaccharides, such as glucose and fructose, and referred to as carbon catabolite repression. To date, efforts have been made to identify the mechanism by which cells sense extracellular monosaccharide concentrations and trigger the genes involved in the repression pathway. The aim of the present work was to quantitatively investigate the cellular regulation of invertase expression in the wild‐type strain S. cerevisiae CEN.PK113‐7D during batch growth containing mixed sugar substrates under different initial conditions.Because of the high frequency and accurate online analysis of multiple components, a tight control of invertase expression could be observed, and threshold concentrations of the monosaccharides for derepression could be determined to 0.5 gl−1 for glucose and 2 gl−1 for fructose. Also, the existence of a hitherto undescribed regulatory state, in which cells regulate invertase expression very precisely and operate over long periods at monosaccharide concentrations lower than the above thresholds, could be demonstrated. All experimental observations could be summarized in a formulation of the cellular regulation scheme of invertase expression. A simple kinetic model could show that the regulation scheme explains the observed behavior very well. Additionally, the model was able to explain consequences of the regulation on the global metabolism. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 247–258, 2001.