bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cibacron Blue F3GA incorporated magnetic poly(2‐hydroxyethyl methacrylate) beads for lysozyme adsorption
Authors: Odabaşı Mehmet , Denizli Adil 
Published: April 2004

AbstractLysozyme adsorption onto Cibacron Blue F3GA incorporated magnetic poly(2‐hydroxyethyl methacrylate) (mag‐PHEMA) beads was investigated. Mag‐PHEMA beads (80–120 μm) were produced by dispersion polymerization. The triazine dye Cibacron Blue F3GA was incorporated covalently as a dye ligand. These dye‐incorporated beads, having a swelling ratio of 34% (w/w) and carrying different amounts of Cibacron Blue F3GA (12.2–42.8 μmol/g) were used in lysozyme adsorption studies. The effects of the initial concentration, pH, ionic strength, and temperature on the adsorption efficiency of dye‐incorporated beads were studied in a batch reactor. The effects of the Cibacron Blue F3GA loading on the lysozyme adsorption were also studied. The nonspecific adsorption of lysozyme on the mag‐PHEMA beads was 0.8 mg/g. Cibacron Blue F3GA attachment significantly increased the lysozyme adsorption up to 295 mg/g. More than 90% of the adsorbed lysozyme was desorbed in 1 h in a desorption medium containing 1.0M KSCN at pH 8.0. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 719–725, 2004
Effect of the amorphous segment on the nonisothermal crystallization and morphology of oxyethylene–oxybutylene block copolymers
Authors: Xu Jun‐Ting , Xue Liang , Mai Shao‐Min , Ryan A. J. 
Published: April 2004

AbstractThe nonisothermal crystallization and morphology of three oxyethylene–oxybutylene block copolymers with different architectures (E50B70, B65E75B65, and E35B114E35) were compared with those of three blends (E56B27/B14, B37E77B37/B14, and E38B38E38/B14) with the same composition and morphology (E and B represent oxyethylene and oxybutylene units, respectively, and the subscripts denote the degree of polymerization), and the effect of the amorphous block was examined. The neat block copolymers had larger d‐spacings and higher melting temperatures than the corresponding blends. In nonisothermal crystallization, the neat block copolymers had lower crystallization temperatures at high cooling rates. The difference in the crystallization temperatures became smaller at low cooling rates, and some of the neat block copolymers could have higher crystallization temperatures. Polarized optical microscopy showed that the neat block copolymers had smaller dimensions of crystal growth and smaller size of spherulites than the blends. The lower crystallization temperatures and less perfect morphology were attributed to the slower rate of conformational rearrangement of the amorphous block, which was required by the chain folding of the crystallizable block. This effect was more evident in the E35B114E35 triblock copolymer, in which both ends of the amorphous B block were immobilized at the interface. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 870–876, 2004
Isothermal crystallization behavior of polypropylene catalloys
Authors: Lin Zhonghua , Peng Mao , Zheng Qiang 
Published: April 2004

AbstractThe isothermal crystallization behavior of polypropylene (PP) catalloys and neat PP were studied with differential scanning calorimetry and polarized optical microscopy (POM). The crystallization kinetics of the samples were described with the well‐known Avrami equation. The crystallization rate depended remarkably on the content of the ethylene component in the PP catalloys. The crystallization half‐time increased obviously with the increase of the ethylene component in the PP catalloys. We also observed by POM that in isothermal crystallization, there were many more nuclei in the PP catalloys than that in neat PP and with an increase of the ethylene component, the average size of the spherulites decreased obviously. Even when ethylene content was as high as 27%, the crystallization rate still increased apparently, and this was quite different from common PP melting blends, in which the crystallization rate decreased when the ethylene content was relatively high because of the obstruction effect of dispersed droplets to the spherulite growth of the PP matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 877–882, 2004
Hot compaction of polyethylene naphthalate
Authors: Hine P. J. , Astruc A. , Ward I. M. 
Published: April 2004

AbstractIn this article, we describe the production of single polymer composites from polyethylene naphthalate (PEN) multifilaments by using the hot compaction process. In this process, developed at Leeds University, highly oriented tapes or fibers are processed at a critical temperature such that a small fraction of the surface of each oriented element is melted, which on cooling recrystallizes to form the matrix of the composite. This process is, therefore, a way to produce novel high‐volume fraction polymer/polymer composites where the two phases are chemically the same material. A variety of experimental techniques, including mechanical tests and differential scanning calorimetry, were used to examine the mechanical properties and morphology of the compacted PEN sheets. Bidirectional (0/90) samples were made at a range of compaction temperatures chosen to span the melting range of the PEN multifilaments (268–276°C). Measurement of the mechanical properties of these samples, specifically the in‐plane modulus and strength, allowed the optimum compaction temperature to be ascertained (∼ 271°C), and hence, the optimum mechanical properties. The optimum compacted PEN sheets were found to have an initial modulus close to 10 GPa and a strength of just over 200 MPa. The glass transition temperature of the optimum compacted sheets was measured to be 150°C, nearly 40°C higher than compacted poly(ethylene terephthalate) (PET) sheets. In previous work on polypropylene and PET hot compacted materials, it proved instructive to envisage these materials as a composite where the original oriented multifilaments are regarded as the reinforcing phase, and the melted and recrystallized material are regarded as the matrix phase. Dynamic mechanical bending tests (DMTA) were used here to confirm this for PEN. DMTA tests were carried out on the original fibers and on a sample of completely melted material to determine the fiber and matrix properties, respectively. The composite properties were then predicted by using a simple rule of mixtures and this was found to be in excellent agreement with the magnitude and measured temperature dependence of the hot compacted PEN material. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 796–802, 2004
Synthesis and dynamic mechanical behavior of glucose‐mediated poly(ethylene glycol/chitosan) membrane
Authors: Wang Jian‐Wen , Hon Min‐Hsiung 
Published: April 2004

AbstractThe pH‐dependent chitosan/PEG membrane was prepared by a surface‐mediated process with glucose as a source. Swelling study shows that the glucose‐mediated membrane is more stable in a neutral environment than an acidic one and the stability in all soaking environments generally increases with increasing glucose concentration because of an increase in Schiff's reaction product as demonstrated by a mediated degree analysis. DMA analysis shows that as the glucose concentration increases, the rubber plateau of the glucose‐mediated membrane is prolonged and keeps a higher storage modulus, and the tangent δ peak shifts to a high temperature as the temperature increases. In an isothermal mode, as the glucose concentration increases to 10 wt %, the storage modulus shows a small change in frequency dependence, indicating that the mediating effect is obviously affected by glucose addition. It can also be found that surface‐mediated membrane has a higher complex viscosity than chitosan/PEG membrane at high frequencies. Thus, a new way was found to use glucose to produce stable biomaterial. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 809–820, 2004
Blends of polymers with similar glass transition temperatures: A DMTA and DSC study
Authors: Bikiaris D. , Prinos J. , Botev M. , Betchev C. , Panayiotou C. 
Published: April 2004

AbstractThe miscibility of different polymer blends was studied with dynamic mechanical thermal analysis (DMTA) in conjunction with differential scanning calorimetry (DSC). The blends were prepared by melt mixing polymers having similar glass transitions such as polyglutarimide (PGI), styrene‐co‐maleic anhydride random copolymers (SMA), and polystyrene (PS). In PGI/SMA blends, there is only one glass transition detected with DMTA. In the case of PGI/SMA14 blends, the single glass transition temperature is due to their full miscibility. However, PGI/SMA8 blends are immiscible throughout the whole composition range as was verified by optical observation (opaque appearance), DSC, and scanning electron microscopy. The observation of only one glass transition by DMTA was attributed to weak interactions that take place between the two polymers, leading to partial mutual solubility and bringing the slightly different Tg temperatures of the pure polymers even closer. In SMA8/SMA14 blends, there are two glass transitions detected with DSC as well as with DMTA, indicating that the two copolymers are immiscible. However, in all compositions, shifts of the glass transitions were observed with DMTA, which is evidence of partial miscibility. The observation of immiscibility was easiest in PS/SMA blends by both techniques, because of the bigger difference in glass transition temperatures of the initial polymers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 726–735, 2004
Flexible and conducting composites of polypyrrole and polydimethylsiloxane
Authors: Çakmak Güliz , Küçükyavuz Zuhal , Küçükyavuz Savaş 
Published: April 2004

AbstractConductive and flexible polydimethylsiloxane (PDMS)/polypyrrole (PPy) composites were synthesized electrochemically. Electrochemical syntheses were performed at +1.10 V by using p‐toluene sulfonic acid (PTSA) as supporting electrolyte and water as solvent. Composites were characterized by cyclic voltammetry, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy. Conductivity measurements and mechanical tests were also performed. The observed conductivities were in the range of 3.5–7.6 S/cm, indicating that the conductivities of PDMS/PPy composites and that of pure PPy were in the same order of magnitude. Tensile tests revealed that higher percent elongation was obtained by the addition of PDMS. Highly flexible and foldable PDMS/PPy composites were successfully synthesized, which have high conductivities and improved mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 736–741, 2004
Preparation and properties of ethylene propylene rubber (EPR)–clay nanocomposites based on maleic anhydride‐modified EPR and organophilic clay
Authors: Hasegawa Naoki , Okamoto Hirotaka , Usuki Arimitsu 
Published: April 2004

AbstractEthylene propylene rubber–clay nanocomposites (EPR–CNs) were prepared by melt‐compounding maleic anhydride modified EPR (EPR‐MA) with organophilic clay, and their properties were examined. Silicate layers of organophilic clay were found to exfoliate and homogeneously disperse into the nanometer level in the nanocomposites by transmission electron microscopy observation. EPR–CNs exhibited higher tensile moduli compared to EPR‐MA and composites containing conventional fillers such as carbon black, talc. The storage moduli of EPR–CNs were also higher than those of EPR‐MA and the conventional composites. Creep resistances of EPR–CNs were much improved compared for EPR‐MA. Degree of swelling in hexadecane was remarkably restricted. Improvement of these properties is caused because dispersed silicate layers have much large interface with the EPR matrix and are thought to strongly restrain the EPR polymer chains. Nanocomposite technology using small amount of silicate layers is useful to improve properties of thermoplastic elastomer. Various kinds of thermoplastic elastomers are expected to be produced by loading of silicate layers with or without conventional fillers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 758–764, 2004
Gel permeation chromatography calibration based on fractal geometry
Authors: Boborodea A. G. , Clemens M. , Daoust D. , Bailly C. 
Published: April 2004

AbstractThe previously developed model [Polym Bull 2000, 44, 525] used to characterize the porous gel inside a gel permeation chromatography (GPC) column, has been extended to also include the interstitial space between the macroscopic gel particles. The hydrodynamic dimensions for 12 polystyrene (PS) standards, measured by GPC with differential refractive index (DRI), differential viscometry (VISCO), and multiangle laser light scattering (MALLS) detectors, have been used to determine the fractal parameters of the polystyrene–divinylbenzene gel corresponding to four commercial columns. The new developed model enables to predict the calibration curve for the sets of coupled columns based on the parameters of each column. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 771–777, 2004
Information grounds and the use of need‐based services by immigrants in Queens, New York: A context‐based, outcome evaluation approach
Authors: Fisher Karen E. , Durrance Joan C. , Hinton Marian Bouch 
Published: April 2004

AbstractWe elaborate on Pettigrew's (1998,1999) theory of information grounds while using an outcome evaluation approach enriched by its focus on context to explore the use of need‐based services by immigrants in New York City. Immigrants have substantial information and practical needs for help with adjusting to life in a new country. Because of differences in language, culture, and other factors such as access, new immigrants are a difficult population to study. As a result, little research has examined their predilections from an information behavior perspective. We report findings from a qualitative study of how literacy and coping skills programs are used by and benefit the immigrant customers of the Queens Borough Public Library (QBPL). From our interviews and observation of 45 program users, staff, and other stakeholders, we derived a grand context (in Pettigrew's terms) woven from three subcontexts: the immigrants of Queens, New York; the QBPL, its service model, and activities for immigrants; and professional contributions of QBPL staff. Our findings are discussed along two dimensions: (a) building blocks toward information literacy, and (b) personal gains achieved by immigrants for themselves and their families. We conclude that successful introduction to the QBPL—as per its mission, programming, and staff—can lead immigrants to a synergistic information ground that can help in meeting broad psychological, social, and practical needs.
A new approach to random mutagenesis in vitro
Authors: Lai Yu‐Ping , Huang Jing , Wang Lin‐Fa , Li Jun , Wu Zi‐Rong 
Published: April 2004

AbstractRandom mutagenesis is a powerful tool for studying the effects of a large number of permutations of a particular DNA sequence and its encoded products. Here we describe a new strategy of conducting in vitro random mutagenesis using ethyl methane sulfonate (EMS). The Bacillus aprN18 gene, coding for a serine protease with fibrinolytic activity, was used as a target gene. To study the mutations of the coding region, rather than the whole plasmid, the 1.4 kb gene fragment was cut out from an expression plasmid and treated with 10 mM EMS at 37°C for 1 h. The treated fragment was then ligated back into the original expression vector and a library of random mutants was constructed in a protease‐deficient Bacillus subtilis strain. A plate assay‐based screening method was used to select for mutant clones with altered enzyme activity, and the change of activity was then confirmed by a semi‐quantitative enzyme assay using liquid culture supernatant. The inserts of five clones with altered enzyme activity were randomly chosen for sequencing analysis. Among the point mutations detected, GC → AT transition accounts for 42.1%, AT → GC transition 34.2% and GC/CG transversion 23.7%, respectively. To our knowledge this is the first application of EMS for in vitro mutagenesis of a defined DNA sequence. © 2004 Wiley Periodicals, Inc.
Fed‐batch optimization of α‐amylase and protease‐producing Bacillus subtilis using Markov chain methods
Authors: Skolpap Wanwisa , Scharer J.M. , Douglas P.L. , Moo‐Young M. 
Published: April 2004

AbstractA stoichiometry‐based model for the fed‐batch culture of the recombinant bacterium Bacillus subtilis ATCC 6051a, producing extracellular α‐amylase as a desirable product and proteases as undesirable products, was developed and verified. The model was then used for optimizing the feeding schedule in fed‐batch culture. To handle higher‐order model equations (14 state variables), an optimization methodology for the dual‐enzyme system is proposed by integrating Pontryagin's optimum principle with fermentation measurements. Markov chain Monte Carlo (MCMC) procedures were appropriate for model parameter and decision variable estimation by using a priori parameter distributions reflecting the experimental results. Using a simplified Metropolis‐Hastings algorithm, the specific productivity of α‐amylase was maximized and the optimum path was confirmed by experimentation. The optimization process predicted a further 14% improvement of α‐amylase productivity that could not be realized because of the onset of sporulation. Among the decision variables, the switching time from batch to fed‐batch operation (ts) was the most sensitive decision variable. © 2004 Wiley Periodicals, Inc.
Modeling mass transfer in hepatocyte spheroids via cell viability, spheroid size, and hepatocellular functions
Authors: Glicklis Rachel , Merchuk Jose C. , Cohen Smadar 
Published: April 2004

AbstractHepatocyte aggregation into spheroids attributes to their increased activity, but in the absence of a vascular network the cells in large spheroids experience mass transfer limitations. Thus, there is a need to define the spheroid size which enables maximal cell viability and productivity. We developed a combined theoretical and experimental approach to define this optimal spheroid size. Hepatocyte spheroids were formed in alginate scaffolds having a pore diameter of 100 μm, in rotating T‐flasks or spinners, to yield a maximal size of 100, 200, and 600 μm, respectively. Cell viability was found to decrease with increasing spheroid size. A mathematical model was constructed to describe the relationship between spheroid size and cell viability via the oxygen mass balance equation. This enabled the prediction of oxygen distribution profiles and distribution of viable cells in spheroids with varying size. The model describes that no oxygen limitation will take place in spheroids up to 100 μm in diameter. Spheroid size affected the specific rate of albumin secretion as well; it reached a maximal level, i.e., 60 μg/million cells/day in 100‐μm diameter spheroids. This behavior was depicted in an equation relating the specific albumin secretion rate to spheroid size. The calculated results fitted with the experimental data, predicting the need for a critical number of viable hepatocytes to gain a maximal albumin secretion. Taken together, the results on mass transport in spheroids and its effects on cell viability and productivity provide a useful tool for the design of 3D scaffolds with pore diameters of 100 μm. © 2004 Wiley Periodicals, Inc.
Enhancing bioplastic–substrate interaction via pore induction and directed migration of enzyme location
Authors: Lele Bhalchandra S. , Papworth Glenn , Katsemi Vicky , Rüterjans Heinz , Martyano Igor , Klabunde Kenneth J. , Russell Alan J. 
Published: April 2004

AbstractWe demonstrate two novel approaches to enhance interactions of polymer‐immobilized biomolecules with their substrates. In the first approach, diisopropylfluorophosphatase (DFPase) containing poly(urethane) (PU) coatings were made microporous by incorporating, then extracting, poly(ethylene glycol)‐based diesters as porogens. Incorporation of 2% w/w porogen increased the effective diffusion coefficient of diisopropylfluorophosphate (DFP) through the coatings by 30% and increased the apparent turnover number of immobilized DFPase 3‐fold. In the second approach, prior to immobilization, hydrophobic modification of DFPase was achieved through its conjugation with a dimer/trimer mixture of a uretdione based on 1,6‐diisocyanatohexane. When the hydrophobically modified DFPase was immobilized in coatings, catalytic activity was 4‐fold higher than that of the equivalent, immobilized, native DFPase. This activity enhancement was independent of the presence or absence of pores. Confocal microscopy images of coatings containing fluorescently labeled lysozyme show that the native enzyme is distributed uniformly over the entire thickness of the coatings. Hydrophobically modified and fluorescently labeled lysozyme is accumulated only in the upper 10 μm cross‐sectional layer of a 100 μm‐thick coating. Interactions of bioplastics with their substrates are tunable either by pore induction in a polymer or by directed migration of the hydrophobically modified biomolecule to the desired location. The latter approach has broad implications, including overcoming mass transfer limitations experienced by immobilized biocatalysts. © 2004 Wiley Periodicals, Inc.
CFD Sinflow Library: A framework to develop engineering educational codes in CFD and thermal sciences
Authors: Pieritz Romeu André , Mendes Rafael , da Silva Rodrigo F. A. F. , Maliska Clovis R. 
Published: April 2004

AbstractThis work introduces the educational code development library “CFD Sinflow Library” specialized in 2D numerical methods in computational fluid dynamics (CFD) and termal science. This library is for research, educational, and engineering purposes like an open and platform independent architecture. The library was developed with C++ standard programming language using an object‐oriented approach allowing educators and graduation/undergraduation students to access the numerical methods in a simplified way. The numerical capabilities and results quality are evaluated, where comparisons are made with benchmark and analytical solutions. © 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 12: 31–43, 2004; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10056
Development and implementation of a MATLAB simulation project for a multidisciplinary graduate course in autonomous robotics
Authors: Joshi Sanjay S. 
Published: April 2004

AbstractIn this paper, we describe a MATLAB computer simulation course project implemented as part of an introductory graduate course in autonomous robotics at the University of California, Davis. The course consisted of students from Mechanical and Aeronautical Engineering, Psychology and Neuroscience, Electrical Engineering, and Computer Science. Creating a valuable class computer project experience for graduate students with greatly varying backgrounds is a challenging undertaking. Graduate students in different majors may have widely different educational backgrounds, field‐specific language and culture, and computer background. It is a main result of this paper that a meaningful autonomous robotics computer project can be developed that allows students to be individually unique and creative, but at the same time allows each student to understand and share ideas, tools, and methods from all the other students. Simulation project conception, teamwork, implementation, results, and lessons learned are described. © 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 12: 54–64, 2004; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20001