bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystallite size and shape in Twaron fibers heat treated at different temperatures using WAXS
Authors: Jain Anjana , Abhishek S. , Sangappa  , Mahesh S. S. , Somashekar R. 
Published: March 2006

AbstractWe have determined the crystallite size of Twaron fibers heat treated at various temperatures by analyzing the wide angle X‐ray scattering (WAXS) data employing a profile analysis technique developed by us. This study indicates that the differential change of size with temperature is less than 1% of the mean value along both (110) and (200) directions. Hence, these fibers are thermally stable and thermal aging is negligible. We have also observed that the lattice strain variation with temperature is negligible. These studies demonstrate the thermal stability of fibers in terms of the changes in the microcrystalline parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4910–2916, 2006
Analysis of the epoxy polymerization process with piperidine as the initiator
Authors: Aitken Edward A. 
Published: March 2006

AbstractMeasurements of the rate of heating from a polymerization reaction of a popular Epoxy compound, EPON 828, with piperidine as the initiator were made until no further heat output was detectable. The results were obtained using a microcalorimeter at a temperature of 27.5°C. Three experiments were run where the amine equivalents relative to the epoxy equivalents were 0.034, 0.100, and 0.170. At these ratios, the amine was insufficient to bond with all the epoxide rings. Each amine bond produces an oxide ion, which in turn reacts with other epoxide rings creating another oxide ion. This propagation reaction continues until all the epoxy groups are opened and bonded. The heat rate from the epoxy reaction started at a value proportional to the amine content but then it accelerated rapidly by over an order of magnitude and then decelerated after about 50% completion. The heat rate profiles were found to fit a combination of three mechanisms operating during the polymerization. The first stage is generation of an oxide ion by amine reaction and by a hydrogen ion exchange between the unreacted amine and a hydroxyl group present in the EPON 828 molecule. The second stage is the rapid acceleration in heat rate due to a build up of an ether bond from the reaction of the oxide ion with an epoxy group. The peak heating rate occurred when the epoxy rings and ether bonds were equal. The last stage is a classic diffusion process, which is the only mechanism left to allow reaction after the other mechanisms have dissipated. The paper generates rate equations and discusses specific issues arising from the heat rate database. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5066–5086, 2006
Synthesis of Fe3O4/PMMA composite latex particles: Kinetic modeling
Authors: Wang Ping‐Chieh , Chiu Wen‐Yen , Young Tai‐Horng 
Published: March 2006

AbstractIn this work, a generalized mathematical model was developed to estimate the variation of particle concentration during the entire course of soapless emulsion polymerization of methyl methacrylate with ferrofluid. Two mechanisms for the nucleation and growth of particles throughout the polymerization reaction were discussed: Mechanism I – seeded polymerization; and Mechanism II – self‐nucleation polymerization. Here, the self‐nucleation included homogeneous nucleation and micelle nucleation. Coagulation between particles, which came from different nucleation mechanisms during the course of polymerization, was considered and included in this model. When appropriate parameters were selected, this model could be successfully used to interpret the variation of particle concentration during the entire reaction. Under different conditions, rate of polymerization, number of radicals in each particle, average molecular weight of polymers, and rate constant of termination were also calculated. All of them explained the experimental results quite well. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4925–4934, 2006
Superparamagnetic flexible substrates based on submicron electrospun Estane® fibers containing MnZnFeNi nanoparticles
Authors: Gupta Pankaj , Asmatulu Ramazan , Claus Rick , Wilkes Garth 
Published: March 2006

AbstractFlexible, elastomeric, and superparamagnetic substrates were prepared by electrospinning a solution of elastomeric polyurethane containing ferrite nanoparticles (∼14 nm) of MnZnNi. The flexible mats were characterized in terms of fiber morphology and magnetic properties. Field emission scanning electron microscopy (FESEM) indicated that the diameter of these composite fibers was ∼300–500 nm. Furthermore, the back‐scattered electron FESEM images indicated agglomeration of the nanoparticles at higher wt % (ca. 17–26 wt %) loading in the electrospun fibers. The induced specific magnetic saturation and the relative permeability were found to increase linearly with increasing wt % loading of the ferrite nanoparticles on the submicron electrospun fibers. A specific magnetic saturation of 1.7–6.3 emu/g at ambient conditions indicated superparamagnetic behavior of these composite electrospun substrates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4935–4942, 2006
BIMS/filler interactions. I. Effects of filler structure
Authors: Tse M. F. 
Published: March 2006

AbstractPolymer/filler interactions have been found to affect the performance of tire tread, sidewall, innerliner, or carcass and other industrial rubber products that are all based on filled elastomers. Identification of types of various polymer/filler interactions and ranking of their impacts have been elusive. Isobutylene‐based polymers have relatively saturated structures and contain very low concentrations of functional group. Examples are BIMS (a brominated isobutylene/p‐methylstyrene copolymer) containing p‐bromomethylstyrene and p‐methylstyrene; bromobutyl rubber containing Br and olefin; chlorobutyl rubber containing Cl and olefin; and butyl rubber containing olefin. On the other hand, high diene rubbers, such as polybutadiene rubber, polyisoprene rubber, and styrene/butadiene rubber, have unsaturated backbones and high olefin contents. Hence, different types and extents of interaction with reinforcing fillers, such as carbon black (CB) or silica, are expected in these two classes of elastomer. This work employs bound rubber (solvent extraction), viscoelasticity, stress–strain measurements, and solid state NMR to identify, differentiate, and scale polymer/filler interactions in unvulcanized BIMS/CB, BIMS/silica, SBR/CB, and SBR/silica composites, where SBR denotes a styrene/butadiene rubber. Four different types of CB and one type of silica have been studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4943–4956, 2006
A nanofoaming process and dielectric properties of polymethylphenylsilsesquioxane‐based nanofoams
Authors: Hong Soo Man , Hwang Seung Sang 
Published: March 2006

AbstractWe prepared polymethylphenylsilsesquioxane (PMPSQ) as an inorganic, thermally stable, matrix and poly‐D,L‐lactide‐1,6‐hexanediol (PDLLA‐1,6‐hexanediol) as a porogen material. PMPSQ was initially designed to obtain synergistic effects from polyphenylsilsesquioxane and polymethylsilsesquioxane. The PDLLA‐1,6‐hexanediol was chosen as a porogen since it has a much lower thermal stability when compared with PMPSQ. The initial decomposition temperature of the PMPSQ (458°C) was higher than the terminal decomposition temperature of PDLLA‐1,6‐hexanediol by 148°C, resulting in a broad processing window for the nanofoaming process. The broad window was utilized not only for optimization of the foaming condition, but for preparation of the nanofoamed PMPSQ without disruption in the structural stability of the matrix. Furthermore, hydroxyl end groups on PMPSQ and PDLLA‐1,6‐hexanediol played a role in the uniform and well‐distributed phase separation behavior. PMPSQ and PDLLA‐1,6‐hexanediol were investigated by 1H NMR, GPC, and thermogravimetric analysis to characterize the properties of polymers and optimize the foaming condition. The inorganic/organic hybrids based on the PMPSQ and PDLLA‐1,6‐hexanediol were prepared and measured in terms of phase separation behavior and dielectric properties. In these hybrid systems, PMPSQ/PDLLA‐1,6‐hexanediol (85/15) exhibited the most uniform and the smallest nanofoam distribution in the continuous PMPSQ matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4964–4971, 2006
Molecular characteristics of room‐temperature soluble fractions of low‐density polyethylene film resins
Authors: Yu Youlu , Tso Chung C. , DesLauriers Paul J. 
Published: March 2006

AbstractThe molecular characteristics of the room‐temperature soluble fractions (RT solubles) of three low‐density polyethylene film resins were characterized by size‐exclusion chromatography (SEC), SEC combined with FTIR (SEC–FTIR), and nuclear magnetic resonance spectroscopy (NMR). The high‐molecular‐weight components of the RT solubles were found to be highly branched components with uniform short‐chain branching (SCB) profiles. For the low‐molecular‐weight components, however, SCB content was a function of molecular weight (MW), increasing with an increase in MW. When the chain ends were considered as SCB equivalents, the distribution of the sum of SCB and chain ends across the molecular weight distribution was practically flat, suggesting that the driving force for polymer chains remaining in solution at RT was the length of the undisrupted methylene sequence in the backbone, or methylene run length, which was too short to form crystal lamellae with a melting temperature above RT, regardless of the molecular weight of the polymer. Moreover, the NMR results revealed that the polymer components of the RT solubles had “superrandom” SCB distributions, that is, the fraction of comonomer clusters in the polymer chains of the RT solubles was lower than that predicted by Bernoullian statistical analysis, indicating that the probability of adding a comonomer to a comonomer‐ended propagating chain was lower than that of adding a comonomer to an ethylene‐ended one, presumably because of an unfavorable steric effect. Furthermore, contrary to the common belief that RT solubles are mainly low‐molecular‐weight polymers, high‐molecular‐weight components were found in high concentrations in the RT solubles, with a cutoff MW as high as 1,000,000 g/mol. The proportion of RT solubles in the film resins was found to depend on the type of resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4992–5006, 2006
Optimization of the hot alkali treatment of polyester/cotton fabric with sodium hydrosulfite
Authors: Montazer M. , Sadighi A. 
Published: March 2006

AbstractThe treatment of cotton or polyester fabric in alkali media is a common modification process for producing a fabric with desirable qualities. Alkali treatment of polyester/cotton fabric could produce a fabric with better performance. In this research, polyester/cotton fabric was treated with NaOH at different temperatures and times. The results show that alkali treatment at the optimum temperature and time with NaOH could hydrolyze the polyester fiber surface and remove some of the impurities from the cotton fiber at the same time and may also improve some of the fabric properties, such as fabric regain, water drop absorbency, and fabric pilling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5049–5055, 2006
Porous dye affinity beads for nickel adsorption from aqueous solutions: A kinetic study
Authors: Akgöl Sinan , Kuşvuran Erdal , Kara Ali , Şenel Serap , Denizli Adil 
Published: March 2006

AbstractWe investigated a new adsorbent system, Reactive Red 120 attached poly(2‐hydroxyethyl methacrylate ethylene dimethacrylate) [poly(HEMA–EDMA)] beads, for the removal of Ni2+ ions from aqueous solutions. Poly(HEMA–EDMA) beads were prepared by the modified suspension copolymerization of 2‐hydroxyethyl methacrylate and ethylene dimethacrylate. Reactive Red 120 molecules were covalently attached to the beads. The beads (150–250 μm), having a swelling ratio of 55% and carrying 25.5 μmol of Reactive Red 120/g of polymer, were used in the removal of Ni2+ ions. The adsorption rate and capacity of the Reactive Red 120 attached poly(HEMA–EDMA) beads for Ni2+ ions was investigated in aqueous media containing different amounts of Ni2+ ions (5–35 mg/L) and having different pH values (2.0–7.0). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 60 min. The maximum adsorption of Ni2+ ions onto the Reactive Red 120 attached poly(HEMA–EDMA) beads was 2.83 mg/g at pH 6.0. The nonspecific adsorption of Ni2+ ions onto poly(HEMA–EDMA) beads was negligible (0.1 mg/g). The desorption of Ni2+ ions was studied with 0.1M HNO3. High desorption ratios (>90%) were achieved. The intraparticle diffusion rate constants at various temperatures were calculated as k20°C = 0.565 mg/g min0.5, k30°C = 0.560 mg/g min0.5, and k40°C = 0.385 mg/g min0.5. Adsorption–desorption cycles showed the feasibility of repeated use of this novel adsorbent system. The equilibrium data fitted very well both Langmuir and Freundlich adsorption models. The pseudo‐first‐order kinetic model was used to describe the kinetic data. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5056–5065, 2006
Bayesian Inference for a Correlated 2 × 2 Table with a Structural Zero
Authors: Stamey James D. , Seaman John W. , Young Dean M. 
Published: March 2006

AbstractWe develop a new Bayesian approach to interval estimation for both the risk difference and the risk ratio for a 2 × 2 table with a structural zero using Markov chain Monte Carlo (MCMC) methods. We also derive a normal approximation for the risk difference and a gamma approximation for the risk ratio. We then compare the coverage and interval width of our new intervals to the score‐based intervals over various parameter and sample‐size configurations. Finally, we consider a Bayesian method for sample‐size determination. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Regression as a Method to Predict Copy Numbers in Comparative Genomic Hybridization Studies on Bacteria
Authors: Feten Guri , Almøy Trygve , Snipen Lars , Aakra Ågot , Aastveit Are H. 
Published: March 2006

AbstractComparative genomic hybridizations (CGH) using microarrays are performed with bacteria in order to determine the level of genomic similarity between various strains. The microarrays applied in CGH experiments are constructed on the basis of the genome sequence of one strain, which is used as a control, or reference, in each experiment. A strain being compared with the known strain is called the unknown strain. The ratios of fluorescent intensities obtained from the spots on the microarrays can be used to determine which genes are divergent in the unknown strain, as well as to predict the copy number of actual genes in the unknown strain. In this paper, we focus on the prediction of gene copy number based on data from CGH experiments.We assumed a linear connection between the log2 of the copy number and the observed log2‐ratios, then predictors based on the factor analysis model and the linear random model were proposed in an attempt to identify the copy numbers. These predictors were compared to using the ratio of the intensities directly.Simulations indicated that the proposed predictors improved the prediction of the copy number in most situations. The predictors were applied on CGH data obtained from experiments with Enterococcus faecalis strains in order to determine copy number of relevant genes in five different strains. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling the utilization of starch by activated sludge for simultaneous substrate storage and microbial growth
Authors: Karahan Özlem , van Loosdrecht Mark C. M. , Orhon Derin 
Published: March 2006

AbstractThis paper presents a mechanistic model incorporating microbial growth on external substrate with simultaneous formation of storage biopolymers (activated sludge model for growth and storage‐ASMGS) for the utilization of starch by activated sludge. Model description and calibration utilized experimental data of an SBR fed with particulate native potato starch (NPS) and soluble starch (SolS) selected as model substrates. The fate of starch was monitored in a cycle together with glycogen and oxygen uptake rate (OUR) profiles. In the experiments, glycogen formation was significantly lower than predicted by total conversion of starch to glycogen, justifying the need to account for primary growth on starch. The proposed model basically modified Activated Sludge Model No.3 (ASM3), to include adsorption of starch, its hydrolysis and simultaneous growth and glycogen formation using the hydrolysis products, which was mainly maltose. Model simulations indicated hydrolysis of the adsorbed starch as the rate limiting process. The proposed model calibrated well the fate of all major model components, namely, starch, glycogen, and OUR. Particulate NPS and SolS were hydrolyzed with similar rates; however, primary and secondary growth processes on SolS were more efficient, with higher yields, due to the more easily utilizable products of SolS, both in terms of extracellular hydrolysis and of stored poly‐glucose. Modeling with ASM3, assuming starch as either readily or slowly biodegradable, did not provide an equally acceptable fit for the glycogen and OUR curves; supporting the need to consider primary growth together with storage as defined in the proposed model. © 2006 Wiley Periodicals, Inc.
Chromate reduction by immobilized palladized sulfate‐reducing bacteria
Authors: Humphries A.C. , Mikheenko I.P. , Macaskie L.E. 
Published: March 2006

AbstractResting cells of Desulfovibrio vulgaris NCIMB 8303 and Desulfovibrio desulfuricans NCIMB 8307 were used for the hydrogenase‐mediated reduction of Pd(II) to Pd(0). The resulting hybrid palladium bionanocatalyst (Bio‐Pd(0)) was used in the reduction of Cr(VI) to the less environmentally problematic Cr(III) species. The reduction of Cr(VI) by free and agar‐immobilized Bio‐Pd(0) was evaluated. Investigations using catalyst suspensions showed that Cr(VI) reduction was similar (∼170 nmol Cr(VI)/h/mg Bio‐Pd(0)) when Bio‐Pd(0) was produced using D. vulgaris or D. desulfuricans. Continuous‐flow studies using D. vulgaris Bio‐Pd(0) with agar as the immobilization matrix investigated the effect of Bio‐Pd(0) loading, inlet Cr(VI) concentration, and flow rate on the efficiency of Cr(VI) reduction. Reduction of Cr(VI) was highest at a D. vulgaris Bio‐Pd(0) loading of 7.5 mg Bio‐Pd(0)/mL agar (3:1 dry cell wt: Pd(0)), an input [Cr(VI)] of 100 µM, and a flow rate of 1.75 mL/h (approx. 3.5 column volumes/h). A mathematical interpretation predicted the activity of the immobilized Bio‐Pd(0) for a given set of conditions within 5% of the value found by experiment. Considering the system as an ‘artificial enzyme’ analog and application of applied enzyme kinetics gave an apparent Km value (Km app) of 430 µM Cr(VI) and a determined value of flow‐through reactor activity which differed by 11% from that predicted mathematically. © 2006 Wiley Periodicals, Inc.
Kinetics and equilibria of lysozyme precipitation and crystallization in concentrated ammonium sulfate solutions
Authors: Cheng Yu‐Chia , Lobo Raul F. , Sandler Stanley I. , Lenhoff Abraham M. 
Published: March 2006

AbstractThe kinetics and thermodynamics of lysozyme precipitation in ammonium sulfate solutions at pH 4 and 8 and room temperature were studied. X‐ray powder diffraction (XRD) was used to characterize the structure of lysozyme precipitates. It was found that, if sufficient time was allowed, microcrystals developed following an induction period after initial lysozyme precipitation, even up to ionic strengths of 8 m and at acidic pH, where lysozyme is refractory to crystallization in ammonium sulfate. The full set of precipitation and crystallization data allowed construction of a phase diagram of lysozyme, showing the ammonium sulfate dependence. It suggests that precipitation may reflect a frustrated metastable liquid‐liquid phase separation, which would allow this process to be understood within the framework of the generic phase diagram for proteins. The results also demonstrate that XRD, more frequently used for characterizing inorganic and organic polycrystalline materials, is useful both in characterizing the presence of crystals in the dense phase and in verifying the crystal form of proteins. © 2006 Wiley Periodicals, Inc.
Kinetic modeling to optimize pentose fermentation in Zymomonas mobilis
Authors: Altintas Mehmet M. , Eddy Christina K. , Zhang Min , McMillan James D. , Kompala Dhinakar S. 
Published: March 2006

AbstractZymomonas mobilis engineered to express four heterologous enzymes required for xylose utilization ferments xylose along with glucose. A network of pentose phosphate (PP) pathway enzymatic reactions interacting with the native glycolytic Entner Doudoroff (ED) pathway has been hypothesized. We have investigated this putative reaction network by developing a kinetic model incorporating all of the enzymatic reactions of the PP and ED pathways, including those catalyzed by the heterologous enzymes. Starting with the experimental literature on in vitro characterization of each enzymatic reaction, we have developed a kinetic model to enable dynamic simulation of intracellular metabolite concentrations along the network of interacting PP and ED metabolic pathways. This kinetic model is useful for performing in silico simulations to predict how varying the different enzyme concentrations will affect intracellular metabolite concentrations and ethanol production rate during continuous fermentation of glucose and xylose mixtures. Among the five enzymes whose concentrations were varied as inputs to the model, ethanol production in the continuous fermentor was optimized when xylose isomerase (XI) was present at the highest level, followed by transaldolase (TAL). Predictions of the model that the interconnecting enzyme phosphoglucose isomerase (PGI) does not need to be overexpressed were recently confirmed through experimental investigations. Through such systematic analysis, we can develop efficient strategies for maximizing the fermentation of both glucose and xylose, while minimizing the expression of heterologous enzymes. © 2006 Wiley Periodicals, Inc.
Biohydrogen production in granular up‐flow anaerobic sludge blanket (UASB) reactors with mixed cultures under hyper‐thermophilic temperature (70°C)
Authors: Kotsopoulos Thomas A. , Zeng Raymond J. , Angelidaki Irini 
Published: March 2006

AbstractHyper‐thermophilic hydrogen production without methane was demonstrated for the first time in granular up‐flow anaerobic sludge blanket (UASB) system fed with glucose using mixed cultures. The maximum hydrogen yield in this study was 2.47 ± 0.15 mol H2/mol glucose. This high yield has never been previously reported in mixed culture systems and it was likely due to more favorable thermodynamic conditions at hyper‐thermophilic temperatures. Different start‐up strategies (bromoethanosulfonate (BES) addition and flow recycle) were evaluated. BES addition during start‐up prevented the establishment of methanogenic cultures in granules. Flow recycle was important to achieve higher hydrogen yield through enriching better hydrogen‐producing organisms and reduced the start‐up period as well. This study indicated UASB system was a promising system for hydrogen production. © 2006 Wiley Periodicals, Inc.