bluuebunny/crossref_metadata_2025_split huggingface dataset:
Significant decreased dielectric constant and loss of polystyrene–clay nanocomposite materials by using long‐chain intercalation agent
Authors: Wang Hong‐Wen , Chang Kung‐Chin , Chu Hsuan‐Chih , Liou Shir‐Joe , Yeh Jui‐Ming 
Published: April 2004

AbstractPolystyrene–clay nanocomposite (PsCN) materials have been prepared by a free radical polymerization process. Montmorillonite (MMT), modified by two different organics, was investigated: one contains a short chain and three benzyl groups on the ammonium ion (DAETPB), while the other contains a long chain (HTAC). The organic modification determines the extent of exfoliation or intercalation of the materials. Exfoliation is more likely to occur using HTAC, as then the gallery of clay has been opened more due to the long chain structure. Exfoliation of MMT in polystyrene (PS) matrix was revealed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were employed to confirm the increased thermal stability of these PsCN materials. Dielectric properties of polystyrene‐clay nanocomposites, in the form of film with clay loading from 1.0 to 5.0 wt %, were measured under frequencies of 100 Hz∼1 MHz at 25∼70°C. Decreased dielectric constant and low dielectric loss were observed for PsCN materials. Especially, the decrease of dielectric constant was found to be related to the extent of exfoliation of clay. It is recognized that the confinement effect of clay results in the suppression of the dielectric response of the nanocomposite materials at low frequency. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2402–2410, 2004
Influence of the comonomers (styrene and methyl acrylate) on the rate of photocrosslinking of 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}‐ phenyl acrylate
Authors: Arun A. , Reddy B. S. R. 
Published: April 2004

Abstract[2,6‐Bis(4‐hydroxybenzylidene)cyclohexanone] (HBC) was prepared by reacting cyclohexanone and p‐hydroxybenzaldehyde in the presence of acid catalyst. Acrylated derivative of HBC, 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}phenyl acrylate (HBA), was prepared by reacting HBC with acryloyl chloride in the presence of triethylamine. Copolymers of HBA with styrene (S) and methyl acrylate (MA) of different feed compositions were carried out by solution polymerization technique by using benzoyl peroxide (BPO) under nitrogen atmosphere. All monomers and polymers were characterized by using IR and NMR techniques. Reactivity ratios of the monomers present in the polymer chain were evolved by using Finnman–Ross (FR), Kelen–Tudos (KT), and extended Kelen–Tudos (ex‐KT) methods. Average values of reactivity were achieved by the following three methods: r1 (S) = 2.36 ± 0.45 and r2 (HBA) = 0.8 ± 0.31 for poly(S‐co‐HBA); r1 = 1.62 ± 0.06 (MA); and r2 = 0.12 ± 0.07 (HBA) for poly(MA‐co‐HBA). The photocrosslinking property of the polymers was done by using UV absorption spectroscopic technique. The rate of photocrosslinking was enhanced compared to that of the homopolymers, when the HBA was copolymerized with S and MA. Thermal stability and molecular weights (Mw and Mn) were determined for the polymer samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2494–2503, 2004
Radiation synthesis and characterization of poly(N‐vinyl‐2‐pyrrolidone/acrylic acid) and poly(N‐vinyl‐2‐pyrrolidone/acrylamide) hydrogels for some metal‐ion separation
Authors: Hegazy El‐Sayed A. , Abd El‐Aal S. E. , Abou Taleb M. F. , Dessouki A. M. 
Published: April 2004

AbstractTwo different hydrogels, prepared from N‐vinyl‐2‐pyrrolidone/acrylic acid (NVP/AAc) and N‐vinyl‐2‐pyrrolidone/acrylamide (NVP/AAm), were studied for the separation and extraction of some heavy‐metal ions from wastewater. The hydrogels were prepared by the γ‐radiation‐induced copolymerization of the aforementioned binary monomer mixtures. Further modification was carried out for the NVP/AAc copolymer through an alkaline treatment to improve the swelling behavior by the conversion of the carboxylic acid groups into its sodium salts. The thermal stability and swelling properties were also investigated as functions of the N‐vinyl‐2‐pyrrolidone content. The characterization and some selected properties of the prepared hydrogels were studied, and the possibility of their practical use in wastewater treatment for heavy metals such as Cu, Ni, Co, and Cr was investigated. The maximum uptake for a given metal was higher for a treated NVP/AAc hydrogel than for an untreated NVP/AAc hydrogel and was higher for an untreated NVP/AAc hydrogel than for an NVP/AAm hydrogel. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2642–2652, 2004
Effect of epolene E‐43 as a compatibilizer on the mechanical properties of palm fiber–poly(propylene) composites
Authors: Abu‐Sharkh B. F. , Kahraman R. , Abbasi S. H. , Hussein I. A. 
Published: April 2004

AbstractComposites of palm fibers and poly(propylene) (PP) were compounded in an extruder at 200°C. The composites were subsequently injection molded into standard tensile specimens for mechanical characterization. The fracture morphology of the specimens was analyzed by scanning electron microscopy. It was observed that the composite modulus increased with the increase of fiber content, indicating the existence of adhesion between PP and the much stiffer palm fibers. However, the adhesion was not satisfactory and resulted in a decrease in the composite tensile strength with fiber addition. The compatibilizer Epolene E‐43 was used to minimize this incompatibility between the wood fibers and the PP matrix. The maleated PP additive enhanced the fiber–matrix adhesion, resulting in an improvement in composite performance. Also, small fibers showed better mechanical properties than those of long fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2581–2592, 2004
Investigation on the kinetic mechanism of structure healing for block copolymer materials after large elongation
Authors: Wang You , Wang Binsong , Shen Jingshu 
Published: April 2004

AbstractThe kinetic mechanism of structure healing after unloading from large elongation for styrene–butadiene–styrene (SBS) block copolymer materials was investigated by following their residual deformation recovery behaviors upon annealing. A linear relationship was found to exist between the deformation recovery percentage and the logarithm of time at different temperatures, which shed light on the mechanism of structure healing. A modified activation energy model was proposed to describe the kinetics of the process. It was also found that the model agrees well with other SBS structure healing–related experimental data such as the recovery of hardness as well as dynamic mechanical property after large elongation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2593–2598, 2004
Preparation of narrowly distributed nanoparticles of poly(n‐butyl methacrylate‐co‐vinyl pyrrolidone) through microemulsion polymerization
Authors: He Wei‐Dong , Ye Fang‐Mao , Wang Yan‐Mei , Li Lin‐Feng 
Published: April 2004

AbstractNarrowly distributed nanoparticles of poly (n‐butyl methacrylate‐co‐vinyl pyrrolidone) were prepared through microemulsion polymerization with a nonionic surfactant of Tween‐80 as emulsifier (6 wt % of the latex) and n‐butanol as coemulsifier. The polymerizations were initiated with benzoylperoxide (BPO), potassium persulfate (KPS), KPS/ferric sulfate (FeSO4), and BPO/FeSO4, respectively, where the initiation in the case of BPO/FeSO4 took place mainly at the interphase between the oil phase and the reaction media. Namely, this interfacial‐initiated microemulsion polymerization resulted in larger particles with relatively narrower particle size distribution as well as higher limiting monomer conversion but lower polymerization rate compared with the polymerization initiated with KPS/FeSO4. In this article, the influences of initiation method, monomer ratio, and addition of water‐soluble components on microemulsion polymerization and latex particle size were studied to discuss the mechanism of interfacial‐initiated microemulsion polymerization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2334–2340, 2004
Analysis of stability of food emulsions by Eyring's theory: Influence of different biopolymers
Authors: Dolz M. , Hernández M. J. , Cabeza C. , Casanovas A. , Delegido J. 
Published: April 2004

AbstractEyring's kinetic theory of liquids was applied to the study of flow behavior of low oil content mayonnaises at different temperatures. These food emulsions were formulated with different biopolymers as stabilizers (polysaccharides such as modified starch, gellan gum, and pectin). The analysis of the values obtained for the parameters of the Eyring equation for viscosity determined the emulsion containing only starch as a stabilizer is the most unstable to stirring. Replacement of part of the starch with gellan gum or pectin enhances the stability of the emulsion. The results for activation energy are quite similar for high shear rates, which can be explained by the evolution of the average drop size distribution. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2653–2657, 2004
Evolution of electrooptical properties of epoxy–amine thermoset/liquid crystal blends during polymerization after the gel point of the polymer matrix
Authors: Sannier Lucas , Masood Siddiqi Humaira , Maschke Ulrich , Dumon Michel 
Published: April 2004

AbstractPolymer dispersed liquid crystals (PDLC) were obtained by polymerization‐induced phase separation of the nematic E7 liquid crystal in a reactive diepoxide–diamine thermosetting matrix prepared by polycondensation (in two thermal steps). The evolution of some important electrooptical characteristics (transmittance in the off‐state, threshold voltage, maximum transmittance of the on‐state, transmittance at maximum applied voltage) were studied at three different reaction conversions of the polymer matrix beyond the gel point. The electrooptical curves greatly depended on the reaction conversion, especially beyond the gel point of the polymer matrix. It was found that the transmission in both the off‐state and the on‐state decreased with the extent of cure. In addition, threshold and saturation voltages increased with the reaction conversion. The electrooptical curve showed unusual behavior at approximately 60% of reaction conversion (i.e., near the gel conversion). At higher conversions, the expected normal mode was recovered. We discussed these electrooptical characteristics in the light of the very significant evolution of some properties of the crosslinked polymer matrix (glass‐transition temperatures, concentration of crosslink points, molar mass, and weight fraction of the residual uncrosslinked oligomers), whereas the droplet morphology did not exhibit dramatic changes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2621–2628, 2004
Interaction of poly(maleic anhydride‐alt‐acrylic acid) with transition metal cations, Ni2+, Cu2+, and Cd2+: A study by UV–Vis spectroscopy and viscosimetry
Authors: Kavlak Serap , Kaplan Can Hatice , Güner Ali 
Published: April 2004

AbstractInteractions between poly(maleic anhydride‐alt‐acrylic acid), [poly(MA‐alt‐AA)] and Cu2+, Ni2+, and Cd2+ ions were studied by UV–vis spectroscopy and viscosimetry. Effects of nature and the concentrations of the metal ions on the complex formation were investigated and the formation constants of each complex were determined by the mole‐ratio method. UV–vis studies showed that the complex formation tendency increased in the followed order: Cd(II) < Ni(II) < Cu(II). This order was confirmed by the Irving–William series and the Pearson's classification. The influence of metal ions on the reduced viscosity of poly(MA‐alt‐AA) increased in the following order: Cu(II) < Ni(II) < Cd(II), and this result was explained by the concentration effect. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2698–2705, 2004
Surface treatments of subdenier monofilament polypropylene fibers to optimize their reinforcing efficiency in cementitious composites
Authors: Pei Meishan , Wang Dujin , Zhao Ying , Hu Xianbo , Xu Yizhuang , Wu Jingguang , Xu Duanfu 
Published: April 2004

AbstractThe surface properties of polypropylene (PP) fibers have an important effect on their reinforcing efficiency in cementitious composites. Two new methods of modifying the surface of subdenier monofilament polypropylene fibers were introduced, as well as the performances of the fiber‐reinforced mortar. The results show that the surface modification improved the mechanical performance of the fiber‐reinforced mortars, such as compressive strength and flexural strength, and the reinforcing efficiency depends on the adopted method. The enhanced interfacial bonding between treated fibers and the cementitious matrix, compared with that of unmodified fibers, was investigated using scanning electronic microscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2637–2641, 2004
Simultaneous multiple sample light scattering for analysis of polymer solutions
Authors: Drenski Michael F. , Reed Wayne F. 
Published: April 2004

AbstractAn instrument for performing Simultaneous Multiple Sample Light Scattering (SMSLS) is introduced, which allows multiple, independent polymer samples to be analyzed simultaneously. Three demonstrations of SMSLS capabilities are made; proof of the SMSLS ability to make absolute Rayleigh scattering ratio measurements on well‐defined standards, the monitoring of a biopolymeric degradation process (hyaluronate degradation using hyaluronidase), with subsequent determination of the Michaelis‐Menten constant, and an aggregation process (low concentration gelatin solutions). It is hoped that SMSLS will become a valuable tool for rapid screening and characterization of both equilibrium properties and nonequilibrium processes in polymer solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2724–2732, 2004
Interspecies scaling of the monoclonal anti‐EGF receptor ior EGF/r3 antibody disposition using allometric paradigm: is it really suitable?
Authors: Ducongé Jorge , Fernández‐Sánchez Eduardo , Alvarez Daniel 
Published: March 2004

AbstractThe pharmacokinetic regularity of the murine monoclonal antibody ior EGF/r3 across mammals was studied using allometry. The allometric relationship between the volume of distribution and body weight (W) across mammalian species was characterized by the power equation Vd=218.8 W0.84 (r=0.92), and that for clearance by CL=2.96 W0.76 (r=0.97, excluding the dog). The complex Dedrick plot of the ior EGF/r3 pharmacokinetic data produced a superimposable profile (r=0.73). However, a 4‐fold variation was observed between the expected human ior EGF/r3 clearance and the cancer patients' values, using apolysichron time units. The patients showed clearance values that overreached the prediction, and the neoteny phenomena cannot explain such a difference. The pharmacokinetic data from cancer patients, rather than healthy volunteers, suggested any tumour‐associated drug clearance process as a possible determinant of the mentioned underestimation. Finally, the results obtained in this study confirmed the potential use of allometric scaling to obtain more insight into the similarities and/or differenhyphences of the ior EGF/r3 disposition behaviour among mammals. Copyright © 2004 John Wiley & Sons, Ltd.
Weighting information from outside sources: a biased process
Authors: Luan Shenghua , Sorkin Robert D. , Itzkowitz Jesse 
Published: March 2004

AbstractHow do people utilize information from outside sources in their decisions? Participants observed a signal‐plus‐noise or noise‐alone event and then made a yes–no decision about whether a signal had occurred. Participants were provided with two information sources to aid decision making. Each source consisted of four components that provided estimates of signal likelihood. In Experiment 1, the two sources had equal overall accuracy but differed in the expertise and internal correlation of their components. A regression analysis indicated that participants overweighed the high‐expertise‐high‐correlation source. This bias occurred on trials when the aggregate opinions of the sources disagreed. In Experiment 2, both the overall accuracy of the source and its components were manipulated. Participants overweighed information from the higher accuracy source. These biases reflect people's sensitivity to across‐trial and within‐trial differences in the accuracy and internal consistency of information sources. Experiment 3 provided additional evidence supporting these conclusions. Copyright © 2004 John Wiley & Sons, Ltd.
Search strategies in decision making: the success of “success”
Authors: Newell Ben R. , Rakow Tim , Weston Nicola J. , Shanks David R. 
Published: March 2004

AbstractExamination of search strategies has tended to focus on choices determined by decision makers' personal preferences among relevant cues, and not on learning cue‐criterion relationships. We present an empirical and rational analysis of cue search for environments with objective criteria. In such environments, cues can be evaluated on the basis of three properties: validity (the probability that a cue identifies the correct choice if cue values differ between alternatives); discrimination rate (the proportion of occasions on which a cue has differing values); and success (the expected proportion of correct choices when only that cue can be used). Our experiments show that though there is a high degree of individual variability, success is a key determinant of search. Furthermore, a rational analysis demonstrates why success‐directed search is the most adaptive strategy in many circumstances. Copyright © 2004 John Wiley & Sons, Ltd.
Contingent application of the cancellation editing operation: the role of semantic relatedness between risky outcomes
Authors: Bonini Nicolao , Tentori Katya , Rumiati Rino 
Published: March 2004

AbstractThis article presents findings on the restructuring component of the decision process. Two experiments are described employing hypothetical vacation choice dilemmas. The aim was to explore the conditions under which outcomes common to two risky prospects with the same probabilities of occurrence are or are not cancelled and how consequent decisions are influenced. The design of the options presented to participants was based on pilot work to establish appropriate contexts. The key independent variable was the semantic relatedness between outcomes of the same risky prospect. The main finding was that the participants did not cancel the outcome shared by two prospects when it was semantically related to another outcome within the same prospect. In this case, the prospect with greater risk was chosen significantly more frequently in comparison to when the common outcome was unrelated to other outcomes. An interpretation of the findings is presented in terms of contingent editing processes. Copyright © 2004 John Wiley & Sons, Ltd.
Transient response of aerobic and anoxic activated sludge activities to sudden substrate concentration changes
Authors: Vanrolleghem Peter A. , Sin Gürkan , Gernaey Krist V. 
Published: April 2004

AbstractThe state‐of‐the‐art understanding of activated sludge processes as summarized in activated sludge models (ASMs) predicts an instantaneous increase in the biomass activity (which is measured, e.g., by the corresponding respiration rate OUR, NUR, etc.) under sudden substrate concentration changes. Experimental data (e.g., short‐term batch respiration experiments under aerobic or anoxic conditions) collected for the calibration of the dynamic models (ASMs) often exhibit a transient phenomenon while attaining maximum activity, which cannot be explained by the current understanding of the activated sludge process. That transient phenomenon exhibits itself immediately upon addition of a substrate source to an endogenously respiring activated sludge sample and it usually takes a few minutes until the activated sludge reaches its maximum possible rate under given environmental conditions. This discrepancy between the state‐of‐the‐art model and the experimental data is addressed in detail in this investigation. It is shown that the discrepancy is not caused by an error in the experimental set‐up/data but it is rather due to model inadequacy. Among the hypotheses proposed, it appears that this transient response of the activated sludge most likely results from the sequence of intracellular reactions involved in substrate degradation by the activated sludge. Results from studies performed elsewhere with pure cultures (S. cerevisae and E. coli) support the hypothesis. The transient phenomenon can be described by a dynamic metabolic network model or by a simple first‐order model, as adopted in this study. The transient phenomenon occurring in short‐term batch respiration experiments is shown to interfere severely with parameter estimation if not modeled properly (2.8%, 11.5%, and 16.8% relative errors [average of three experiments] on YH, μmaxH, and KS, respectively). Proper modeling of this transient phenomenon whose time constant is on the order of minutes (1 to 3 min) is expected to contribute fundamentally to a better understanding and modeling of Orbal, carousel, and SBR‐type treatment plants with fast‐alternating process conditions, although such studies are beyond the scope of this report. © 2004 Wiley Periodicals, Inc.
Kinetics and mechanism of a reaction catalyzed by PST‐01 protease from Pseudomonas aeruginosa PST‐01
Authors: Bobe Iulian M. , Abdelmoez Wael , Ogino Hiroyasu , Yasuda Masahiro , Ishimi Kosaku , Ishikawa Haruo 
Published: April 2004

AbstractThe initial rates of carboxybenzoyl‐alanyl‐l‐leucyl‐amide (Z‐l‐Ala‐l‐Leu‐NH2) synthesis from carboxybenzoyl‐l‐alanine (Z‐l‐Ala) and l‐leucineamide (l‐Leu‐NH2) and Z‐l‐Ala‐l‐Leu‐NH2 hydrolysis in a homogeneous dimethyl sulfoxide‐aqueous buffer solution [1:1 (v/v)] system catalyzed by PST‐01 protease from Pseudomonas aeruginosa were measured under a wide range of Z‐l‐Ala, l‐Leu‐NH2 and Z‐l‐Ala‐l‐Leu‐NH2 concentrations. The initial rates of the synthetic reaction, in which Z‐l‐Ala‐l‐Leu‐NH2 was produced from Z‐l‐Ala and l‐Leu‐NH2, were inhibited by the substrates. Furthermore, the initial rates of the synthetic reaction were not inhibited by the product Z‐l‐Ala‐l‐Leu‐NH2, and those of the hydrolytic reaction were inhibited by Z‐l‐Ala and l‐Leu‐NH2. All the initial rate data of the synthetic and hydrolytic reactions were well correlated with the rate equation derived based on the proposed reaction scheme. © 2004 Wiley Periodicals, Inc.
High‐performance liquid chromatography with ﬂuorescence detection for the simultaneous determination of 3,4‐methylenedioxymethamphetamine, methamphetamine and their metabolites in human hair using DIB‐Cl as a label
Authors: Kaddoumi Amal , Kikura‐Hanajiri Ruri , Nakashima Kenichiro 
Published: March 2004

AbstractThis paper describes a highly sensitive HPLC method for the simultaneous determination of 3,4‐methylenedioxymethamphetamine (MDMA), 3,4‐methylenedioxyamphetamine (MDA), amphetamine (AP) and methamphetamine (MP) in human hair samples. The amphetamines investigated were derivatized with the ﬂuorescent reagent, DIB‐Cl to yield highly ﬂuorescent DIB‐derivatives, which were then analyzed by HPLC with ﬂuorescence detection at excitation and emission wavelengths of 325 nm and 430 nm, respectively. The separation was achieved on an ODS column with an isocratic mobile phase composed of acetonitrile‐methanol‐water (30:40:30, v/v/v). The limits of detection for the four compounds obtained by the proposed method ranged from 11 to 200 pg/mg. The method was successfully applied to the determination of MDMA and MDA in hair samples obtained from MDMA abuser. Copyright © 2004 John Wiley & Sons, Ltd.