bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toward a viscoelastic modeling of anisotropic shrinkage in injection molding of amorphous polymers
Authors: Kwon Keehae , Isayev A. I. , Kim K. H. 
Published: September 2005

AbstractA novel approach to predict anisotropic shrinkage of amorphous polymers in injection moldings was proposed using the PVT equation of state, frozen‐in molecular orientation, and elastic recovery that was not frozen during the process. The anisotropic thermal expansion and compressibility affected by frozen‐in molecular orientation were introduced to determine the anisotropy of the length and width shrinkages. Molecular orientation calculations were based on the frozen‐in birefringence determined from frozen‐in stresses by using the stress‐optical rule. To model frozen‐in stresses during the molding process, a nonlinear viscoelastic constitutive equation was used with the temperature‐ and pressure‐dependent relaxation time and viscosity. Contribution of elastic recovery that was not frozen during the molding process and calculated from the constitutive equation was used to determine anisotropic shrinkage. Anisotropic shrinkages in moldings were measured at various packing pressures, packing times, melt temperatures, and injection speeds. The experimental results of frozen‐in birefringence and anisotropic shrinkage were compared with the simulated data. Experimental and calculated results indicate that shrinkage is highest in the thickness direction, lowest in the width direction, and intermediate in the flow direction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2300–2313, 2005
Reactive mixing of PET and PET/PP blends with glycidyl methacrylate–modified styrene‐b‐(ethylene‐co‐olefin) block copolymers
Authors: Pracella Mariano , Chionna Donatella , Pawlak Andrzej , Galeski Andrzej 
Published: September 2005

AbstractStyrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) and styrene‐b‐(ethylene‐co‐propylene) (SEP, SEPSEP) block copolymers with different styrene contents and different numbers of blocks in the copolymer chain were functionalized by melt radical grafting with glycidyl methacrylate (GMA) and employed as compatibilizers for PET‐based blends. Binary blends of PET with both functionalized (SEBS‐g‐GMA, SEP‐g‐GMA, SEPSEP‐g‐GMA) and neat (SEBS, SEP, SEPSEP) copolymers (75 : 25 w/w) and ternary blends of PET and PP (75 : 25 w/w) with various amounts (2.5–10 phr) of both modified and unmodified copolymers were prepared in an internal mixer, and their properties were evaluated by SEM, DSC, melt viscosimetry, and tensile and impact tests. The roles of the chemical structure, grafting degree, and concentration of the various copolymers on blend compatibilization was investigated. The blends with the grafted copolymers showed a neat improvement of phase dispersion and interfacial adhesion compared to the blends with nonfunctionalized copolymers. The addition of grafted copolymers resulted in a marked increase in melt viscosity, which was accounted for by the occurrence of chemical reactions between the epoxide groups of GMA and the carboxyl/hydroxyl end groups of PET during melt mixing. Blends with SEPSEP‐g‐GMA and SEBS‐g‐GMA, at concentrations of 5–10 phr, showed a higher compatibilizing effect with enhanced elongation at break and impact resistance. The effectiveness of GMA‐functionalized SEBS was then compared to that of maleic anhydride–grafted SEBS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2201–2211, 2005
Phase behaviors of polymer blend(PEO–PPO) electrolyte/LiCF3SO3 systems in lithium battery
Authors: Choi Yong Su , Bae Young Chan , Sun Yang Kook 
Published: September 2005

AbstractPolymer blend (poly(ethylene oxide) (PEO)–poly(propylene oxide) (PPO)) systems with two different mole ratios, complexed with LiCF3SO3 salt, have been characterized at various temperatures and compositions using a thermo‐optical analysis (TOA) technique. We also developed a new melting point depression theory based on the modified perturbed hard sphere chain model to interpret phase behavior of polymer blend electrolyte systems. The obtained results show that the eutectic points move toward higher Tm and lower weight fraction of salt with decreasing PEO mole ratio and also indicate that the mole ratio of PEO–PPO for each polymer blend plays an important role in determining the eutectic point of the polymer blend system. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2314–2319, 2005
The interrelation among network structures, molecular transport of solvent, and creep behaviors of TiB2 ceramic containing butyl rubber composites
Authors: El‐Tantawy Farid 
Published: September 2005

AbstractSwelling of polymer composites in solvents has become one of the major problems in the use of polymer composites exposed to petroleum products. As a possible solution to the problem, this experimental study was conducted to examine the potential application of TiB2 ceramic in butyl rubber (IIR) composites. The effect of TiB2 content on the curing kinetics of IIR composites was studied using a torque rheometer technique. The effect of TiB2 on the network structure was investigated in terms of the crosslinking density, interparticle distance between conducting particles, surface tension, glass transition temperature, degree of crystallinity, scanning electron microscopy, and X‐ray analysis. Moreover, the effect of TiB2 content on the molecular transport of solvent (kerosene) was examined by means of degree of swelling, solvent interaction parameters, volume fraction of rubber, interparticle distance after swelling, penetration rate of solvent, mean diffusion coefficient, cohesive energy density of polymer, standard entropy, standard enthalpy, and standard free energy of IIR composites. It was ascertained that with increasing TiB2 content the degree of swelling shifts to a lower value. The main reason was interpreted as the introduction of good interface adhesion of TiB2 with rubber matrix, which tends to block the diffusion of solvent molecules. The effect of TiB2 content on hardness, tensile strength, Young's modules, and elongation at break is discussed. An apparent steady‐state creep of butyl rubber IIR/TiB2 composites is evident under different constant stresses at room temperature. The strain rate of steady‐state creep showed a dependence on stress and TiB2 volume fraction. The stress sensitivity parameter, viscosity coefficient, and activation volume for samples loaded with different content of TiB2 were estimated. It is apparent that these new composites should be very useful for solvent permeation resistance at high TiB2 loading level with good mechanical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2226–2235, 2005
Effect of the reaction conditions on the photopolymerization of methyl methacrylate by diethyl dithiocarbamato‐(1,2)‐propane diol
Authors: Bhuyan P. K. , Kakati D. K. 
Published: September 2005

AbstractThe photopolymerization of methyl methacrylate (MMA) through the use of diethyl dithiocarbamato‐(1,2)‐propane diol (DCPD) was studied. The photoinitiator was synthesized from 3‐chloro‐1,2‐propane diol and sodium diethyl dithiocarbamate in a solvent mixture of acetone and anhydrous ethanol. The photopolymerization was carried out in a Heber multilamp photochemical reactor (COMPACT‐LP‐MP88) (Heber Scientific, Chennai, India) at 254 nm. The effects of the reaction conditions on the polymerization of MMA were studied. The conversion and molecular weight increased with an increase in the monomer concentration and reaction time. However, for the DCPD‐to‐MMA molar ratio, a critical value was found for maximum conversion. The results suggested the living radical nature of the photoinitiator, which was further investigated by the preparation of a block copolymer with styrene. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2320–2328, 2005
Preparation and properties of poly(methyl methacrylate)/iron carbonate(p) nanocomposites
Authors: Chou Yi‐Chun , Lin C. B. , Yeh Hsiao‐Yun 
Published: September 2005

AbstractThe mass transport of methanol mixed with ferric chloride hexahydrate (FeCl3 · 6H2O) in poly(methyl methacrylate) and poly(methyl methacrylate)/iron carbonate particulate(p) nanocomposites is prepared by chemical vapor crystallization and the resulting materials, which are subjected to characterization to evaluate thermal and optical properties, have been investigated. Mass transport is an anomalous and endothermic process and satisfies the van't Hoff plot. We have prepared successfully poly(methyl methacrylate)(PMMA)/iron carbonate particulates nanocomposites using CO2 gas slowly diffused into saturated solvent mixture‐treated poly(methyl methacrylate) for 48 h. After SEM observation, approximately 80 nm iron carbonate particulates were precipitated and evenly distributed in the poly(methyl methacrylate) matrix. In comparison with solvent mixture‐treated PMMA, the cut‐off wavelength of transmittance in nanocomposites shifts to the shorter wavelength side (red shift). The presence of nanoscale iron carbonate particulates increased the glass transition temperature of the nanocomposites as determined by differential scanning calorimeter, and the glass transition temperature increased with increasing content of nanoscale iron carbonate particulates. The FTIR spectra of solvent mixture‐treated poly(methyl methacrylate) and nanocomposites are also studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2329–2338, 2005
Synthesis and characterization of novel polyurethanes based on 1,3‐bis(hydroxymethyl) benzimidazolin‐2‐one and 1,3‐bis(hydroxymethyl) benzimidazolin‐2‐thione hard segments
Authors: Raghu A. V. , Gadaginamath G. S. , Aminabhavi Tejraj M. 
Published: September 2005

AbstractNovel polyurethanes (PUs) based on 1,3‐bis(hydroxymethyl) benzimidazolin‐2‐one and 1,3‐bis(hydroxymethyl) benzimidazolin‐2‐thione as hard segments with two aromatic diisocyanates, viz., 4,4′‐diphenylmethane diisocyanate and toluene 2,4‐diisocyanate, were prepared. Polymer structures were established by Fourier transform infrared and nuclear magnetic resonance spectroscopy. Morphology of the PUs was studied by differential scanning calorimetry and thermogravimetry. All PUs contain domains of crystalline and amorphous structures as indicated by X‐ray diffraction experiments. Furthermore, polymers were insoluble in the majority of organic solvents and, hence, their solution characterization was not possible. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2236–2244, 2005
Thermal characterization and thermal degradation of copolyimides containing fluorine and phosphine oxide
Authors: Tang Wanjun , Chen Donghua , Yang Zhilan , Zhang Aiqing , Peng Yuhua 
Published: September 2005

AbstractA series of copolyimides containing different ratios of fluorine and phosphine oxide were synthesized. The copolymers were characterized with Fourier transform infrared, differential scanning calorimetry, and thermogravimetric analysis measurements. The copolymers were thermally stable up to 700 K and exhibited glass‐transition temperatures in the range of 495–562 K. The glass‐transition temperatures of the copolymers decreased with an increase in the phosphine oxide content. The thermal decomposition behavior of the copolymers was investigated. The copolymers with higher phosphine oxide contents displayed lower onset decomposition temperatures and char yields. A new method involving the multiple‐rate isotemperature was used to define the most possible mechanism [G(α)] for the reactions. The overall kinetic model function of the thermal decomposition of these copolymers obeyed the Avrami–Erofeev model equation, G(α) = [−ln(1 − α)]1/m, where α is the conversion degree. The apparent kinetic parameters of the degradation processes were also obtained. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2139–2143, 2005
Proteome analysis to assess physiological changes in Escherichia coli grown under glucose‐limited fed‐batch conditions
Authors: Raman Babu , Nandakumar M.P. , Muthuvijayan Vignesh , Marten Mark R. 
Published: September 2005

AbstractProteome analysis was used to compare global protein expression changes in Escherichia coli fermentation between exponential and glucose‐limited fed‐batch phase. Two‐dimensional gel electrophoresis and MALDI‐TOF mass spectrometry were used to separate and identify 49 proteins showing >2‐fold difference in expression. Proteins upregulated during exponential phase include ribonucleotide biosynthesis enzymes and ribosomal recycling factor. Proteins upregulated during fed‐batch phase include those involved in high‐affinity glucose uptake, transport and degradation of alternate carbon sources and TCA cycle, suggesting an enhanced role of the cycle under glucose‐ and energy‐limited conditions. We report the upregulation of several putative proteins (ytfQ, ygiS, ynaF, yggX, yfeX), not identified in any previous study under carbon‐limited conditions. © 2005 Wiley Periodicals, Inc.
Novel quantitative tools for engineering analysis of hepatocyte cultures in bioartificial liver systems
Authors: Sharma N.S. , Ierapetritou M.G. , Yarmush M.L. 
Published: September 2005

AbstractExtracorporeal bioartificial liver devices (BAL) are perhaps among the most promising technologies for the treatment of liver failure, but significant technical challenges remain in order to develop systems with sufficient processing capacity and of manageable size. One key limitation is that during BAL operation, when the device is exposed to plasma from the patient, hepatocytes are prone to accumulate intracellular lipids and exhibit poor liver‐specific functions. Based on hepatic intermediary metabolism, we have utilized mathematical programming techniques to optimize the biochemical environment of hepatocyte cultures towards the desired effect of increased albumin and urea synthesis. To investigate the feasible range of optimal hepatic function, we have obtained a Pareto optimal set of solutions corresponding to liver‐specific functions of urea and albumin secretion in the metabolic framework using multiobjective optimization. The importance of amino acids in the supplementation and the criticality of the metabolic pathways have been investigated using logic‐based programming techniques. Since the metabolite measurements are bound to be patient specific, and hence subject to variability, uncertainty has to be integrated with system analysis to improve the prediction of hepatic function. We have used the concept of two stage stochastic programming to obtain robust solutions by considering extracellular variability. The proposed analysis represents a new systematic approach to analyze behavior of hepatocyte cultures and optimize different operating parameters for an extracorporeal device based on real‐time conditions. © 2005 Wiley Periodicals, Inc.
Strain stability in biological systems treating recalcitrant organic compounds
Authors: Emanuelsson E.A.C. , Baptista I.I.R. , Mantalaris A. , Livingston A.G. 
Published: September 2005

AbstractThe availability of molecular probing technology in recent years has facilitated investigation of microbial community composition during biotreatment of organic wastes. Particularly, it has allowed the study of microbial culture stability and correlation between stability and treatment performance. However, most studies to date have only addressed mixed cultures and there is limited information regarding single strain stability. Here we have investigated the microbial community dynamics in two bioreactors, each inoculated with a pure bacterial strain capable of degrading a recalcitrant substrate, namely Xanthobacter aut. GJ10 degrading 1,2‐dichloroethane (DCE) and Burkholderia sp. JS150 degrading monochlorobenzene (MCB). Universal and strain specific 16S rRNA oligonucleotide probes were designed and used to follow strain stability. The bioreactor fed with DCE was functionally stable and the percentage of GJ10 cells in the community remained high (around 95% of total cells) throughout, even after introduction of foreign microorganisms. The bioreactor fed with MCB was also functionally stable, but in contrast to the DCE bioreactor, probing results revealed the disappearance of strain JS150 from the bioreactor within a week. The difference in behavior between the two systems is attributed to the specific pathway required to degrade DCE. © 2005 Wiley Periodicals, Inc.
Cell cycle synchronization of Cupriavidus necator by continuous phasing measured via flow cytometry
Authors: Fritsch M. , Starruß J. , Loesche A. , Mueller S. , Bley Th. 
Published: September 2005

AbstractThe continuous phasing technique was successfully used to obtain a high degree of cell cycle synchrony in cultures of the model organism Ralstonia eutropha JMP 134 (today reclassified into Cupriavidus necator). The responses of the organism were evaluated with flow cytometric determinations of DNA contents and cell size (by fluorescence and forward scatter measurements, respectively, after staining with the DNA‐binding dye 4′,6‐diamidino‐2′‐phenylindole, DAPI), and cell concentration, after staining with the nucleic acid binding dye LDS‐751. The strain was cultivated on a mineral medium with pyruvic acid sodium salt as the limiting carbon and energy source. Famine conditions, and thus cell dormancy, were achieved in every cycle. The best synchronization, according to the determination of DNA contents, was induced with phasing cycle durations of at least 4 h. The method allows the induction of synchrony for an indefinite period if the medium is exchanged rapidly and precisely. The results show that the time required for a complete cell cycle of Cupriavidus necator JMP 134 is independent of the chosen phasing cycle duration, provided that each process cycle lasts at least 3 h which is much longer than the time needed for a single DNA replication cycle. With shorter cycling periods DNA‐synthesis is carried out in an uncoupled manner and only weak cell cycle synchrony can be attained. The results also show that DNA‐synthesis can only be undertaken by cells when they have exceeded a critical size. © 2005 Wiley Periodicals, Inc.
Stochastic and Relaxation Processes in Argon by Measurements of Dynamic Breakdown Voltages
Authors: Marković V. Lj. , Stamenković S. N. , Gocić S. R. , Petrović Z. Lj. 
Published: September 2005

AbstractStatistically based measurements of breakdown voltages U b and breakdown delay times td and their variations in transient regimes of establishment and relaxation of discharges are a convenient method to study stochastic processes of electrical breakdown of gases, as well as relaxation kinetics in afterglow. In this paper the measurements and statistical analysis of the dynamic breakdown voltages U b for linearly rising (ramp) pulses in argon at 1.33 mbar and the rates of voltage rise k up to 800 V s –1 are presented. It was found that electrical breakdowns by linearly rising (ramp) pulses is an inhomogeneous Poisson process caused by primary and secondary ionization coefficients α , γ and electron yield Y variations on the voltage (time). The experimental breakdown voltage distributions were fitted by theoretical distributions by applying approximate analytical and numerical models. The afterglow kinetics in argon was studied based on the dependence of the initial electron yield on the relaxation time Y 0 (τ ) derived from fitting of distributions. The space charge decay was explained by the surface recombination of nitrogen atoms present as impurities. The afterglow kinetics and the surface recombination coefficients on the gas tube and cathode were determined from a gas‐phase model. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessment of ATM phosphorylation on Ser‐1981 induced by DNA topoisomerase I and II inhibitors in relation to Ser‐139‐histone H2AX phosphorylation, cell cycle phase, and apoptosis
Authors: Kurose Akira , Tanaka Toshiki , Huang Xuan , Halicka H. Dorota , Traganos Frank , Dai Wei , Darzynkiewicz Zbigniew 
Published: September 2005

AbstractBackgroundThe ATM kinase regulates cell‐cycle checkpoints by phosphorylating multiple proteins, including histone H2AX, CHK1, and CHK2 kinases and p53. ATM is activated through auto‐ or trans‐ phosphorylation of Ser‐1981 in response to DNA damage, particularly induction of DNA double‐strand breaks (DSBs). The aim of the present study was to reveal a possible correlation between activation of ATM vis‐à‐vis H2AX phosphorylation, cell cycle phase, and apoptosis in cells treated with DNA topoisomerase (topo) I (topotecan; Tpt) or topo2 (mitoxantrone; Mtx) inhibitor.Materials and MethodsCultures of HL‐60 cells were treated with Tpt or Mtx for various time intervals. ATM or H2AX phosphorylation was detected immunocytochemically, using Ab specific for ATM phosphorylated on Ser‐1981 (ATM‐S1981P) or for H2AX (γH2AX) phosphorylated on Ser‐139, respectively, concurrent with the analysis of cellular DNA content. Cellular fluorescence was measured by flow cytometry.ResultsUntreated cells showed a modest but variable level of labeling with ATM‐S1981P Ab across the cell cycle, with exception of mitotic cells that were strongly labeled. Exposure of cells to 150 nM Tpt induced ATM phosphorylation concurrent with phosphorylation of H2AX within 10 min; phosphorylation of both proteins was essentially limited to S‐phase and was suppressed by caffeine and wortmannin, inhibitors of PI‐3‐like kinases. Exposure of cells to Mtx also led to ATM and H2AX phosphorylation, which, compared to Tpt, occurred later and was not cell‐cycle‐phase specific. Apoptosis of HL‐60 cells in Tpt or Mtx treated cultures was detected after 2 or 4 h, respectively, and was limited to S‐phase cells.ConclusionsThe data are consistent with the role of ATM as a mediator of H2AX phosphorylation in response to DNA damage by topo1 (Tpt) or topo 2 (Mtx) inhibitor. The observed cell‐cycle‐phase related differences in response to Tpt vs Mtx suggest that while the collisions of DNA replication forks with the “cleavable complexes” stabilized by topo1 inhibitor are the primary cause of DSBs induced by Tpt, the collisions of RNA polymerase molecules with the complexes stabilized by the topo2 inhibitor play a major role for induction of DSBs by Mtx. The present report is the first that (i) describes cytometric analysis of ATM activation and (ii) demonstrates activation of the enzyme (kinase) and its consequence (substrate phoshorylation), both in relation to cell‐cycle phase and onset of apoptosis within the same cells. © 2005 International Society for Analytical Cytology
Detection of various platelet‐associated immunoglobulins by flow cytometry in idiopathic thrombocytopenic purpura
Authors: Nishioka Takuya , Yamane Takahisa , Takubo Takayuki , Ohta Kensuke , Park Keunsik , Hino Masayuki 
Published: September 2005

AbstractBackgroundIn 1975, Dixson reported that anti‐platelet IgG on platelets from patients with idiopathic thrombocytopenic purpura (ITP) is greater than in normal people, by determining anti‐platelet antibodies directly on the platelet surface with a quantitative complement lysis–inhibition–assay. Since then, platelet‐associated IgG (PAIgG) has been thought of as evidence of ITP. Although platelets from ITP patients show significantly higher PAIgG values than from normal control individuals, PAIgG is not specific for autoantibody because it increases in other than immune ITP patients.MethodsWe analyzed positive platelet percentage with various platelet‐associated immunoglobulins: IgG, IgM, IgA, and total immunoglobulins, in the blood from 17 normal donors and 23 ITP patients.ResultsThe specificity for ITP disease was better in flow cytometry than in ELISA, because, other than ITP, only aplastic anemia was positive in flow cytometry; however, various disorders (aplastic anemia, chronic lymphocytic leukemia, acute myeloid leukemia, and myelodysplastic syndrome) showed positive in ELISA. Flow cytometry methods had the same sensitivity for ITP disease as ELISA. However, it is supposed that there was no nonimmune ITP in this study because the PAIgG negative patients (n = 1) showed positive results in flow cytometry.ConclusionFlow cytometry method was effective for ITP screening, especially for specificity. © 2005 Wiley‐Liss, Inc.