bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical and thermal properties of waste silk fiber‐reinforced poly(butylene succinate) biocomposites
Authors: Ok Han Seong , Muk Lee Sang , Ho Park Won , Cho Donghwan 
Published: March 2006

AbstractThis article reports the mechanical and thermal properties of poly(butylene succinate) (PBS) biocomposites reinforced with industrially available waste silk fibers, fabricated with varying fiber contents and lengths. The result indicates that use of waste silk fibers may be a potential as reinforcement for effectively improving the static and dynamic mechanical properties of a biodegradable polymer matrix resin, depending on the waste silk fiber content and length in the present biocomposite system. The “as‐separated” waste silk/PBS biocomposites showed the maximum tensile and flexural properties at a fiber loading of 40 wt %, and the “chopped” waste silk/PBS biocomposites showed the optimal strength and modulus with waste silk fibers of 12.7 mm length. The chopped waste silk fibers play a more contributing role in improving the mechanical properties of waste silk/PBS biocomposites than the as‐separated waste silk fibers at a fixed fiber loading. Above the glass transition temperature, the storage modulus of waste silk/PBS biocomposites was significantly greater than that of PBS resin, especially in the higher temperature region. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4972–4980, 2006
Preparation of polysulfone hollow fiber affinity membrane modified with mercapto and its recovery properties. II. Preparation of PSF‐SH hollow fiber affinity membrane for recovery of Hg2+
Authors: Wang Bing , Cheng Bowen , Cui Yongfang 
Published: March 2006

AbstractA high qualified polysulfone hollow fiber affinity membrane modified with mercapto as chelating groups was prepared by phase inversion technology using chlormethyl polysulfone (CMPSF) as membrane matrix materials, through the reaction between thiourea and CMPSF hollow fiber matrix membrane to afford the methyl isothiourium polysulfone and was then alkaline hydrolyzed. The adsorption isotherms of the hollow fiber affinity membrane chromatography for Hg2+ were determined, and the effects of mobile phase conditions and the operating parameters on removal performance of the hollow fiber affinity membrane chromatography for Hg2+ were also investigated. The experimental results showed that adsorption isotherms of Hg2+ could be described by the Langmuir isotherm. Addition of NaCl into feed solution for the increase of ionic strength was harmful for the removal of Hg2+. The recovery of Hg2+ decreased at low pH and the optimum range of pH was from 5.0 to 7.0. The feed concentration had a remote effect on recovery of Hg2+ at the specified loading amount of Hg2+, and the Hg2+ could be removed from different concentration feed solution by the hollow fiber affinity membrane chromatography. The increase of feed flow rate led to slight decrease of recovery of Hg2+ at the specified loading amount of Hg2+. The hollow fiber affinity membrane chromatography could be operated at height feed flow rate and a large scale removal of Hg2+ could be realized. With the increase of load amount, Hg2+ recovery decreased, but the saturation degree of hollow fiber affinity membrane chromatography increased. According to required recovery of Hg2+ and the saturation degree of membrane chromatography, the optimum loading amount of Hg2+ should be selected in the actual removal of Hg2+. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4795–4803, 2006
Reactions of trithiocyanuric acid with oxiranes. IV. Analysis of the initial stages of the synthesis of polyetherols
Authors: Chmiel‐Szukiewicz Elżbieta , Lubczak Jacek 
Published: March 2006

AbstractThe course of the reaction of trithiocyanuric acid (TTCA) with oxiranes, propylene oxide (PO), and epichlorohydrin in a dimethyl sulfoxide solution was monitored by the acid number and epoxy number. The involvement of one of the tautomers of TTCA was postulated on the basis of the studied reaction between TTCA and 3 equiv of oxirane. It was also evidenced that the use of a catalyst was necessary for the reaction between TTCA and an excess of PO. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4917–4920, 2006
Possibility for the light stabilization of polycaproamide for fiber production
Authors: Simeonov N. , Todorova S. 
Published: March 2006

AbstractA considerable setback of polyamide fibers, especially polycaproamidefibers (PCAFs), is their low light resistance. This leads to changes in their appearance and their physicomechanical parameters under ambient atmosphere conditions and as a result of the effect of sunlight. This setback could be compensated to a certain extent by the introduction of suitable light stabilizers in the fiber mass. Depending on its efficiency, each light stabilizer is added at a concentration of 0.2–5% with respect to the mass of the polymer. We have investigated two possibilities for introducing the light stabilizer into the fiber mass. In the first one, the composition was finished immediately after the fiber spinning, and in the second one, polycaproamide granules were processed with a solution of light stabilizers before their melting. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4921–4924, 2006
Synthesis and characterization of sPS/montmorillonite nanocomposites
Authors: Torre L. , Lelli G. , Kenny J. M. 
Published: March 2006

AbstractThe present work analyzed the possibility of obtaining and producing syndiotactic polystyrene (sPS)–based nanocomposites. The work first focused on possible technology to use for intercalation from solution and melt intercalation. Using a blend of sPS with atactic polystyrene (aPS) as the matrix was also considered. Thermal analysis techniques, such as differential scanning calorimetry (DSC) and thermogravimetry (TGA), were used to study the thermal properties and stability of the nanocomposites obtained and to select the most appropriate nanocharges. The effect of the introduction of nanofillers on these properties also was evaluated. X–ray diffraction was used to investigate the degree of clay exfoliation. Finally, mechanical characterization of the nanocomposites obtained was performed and compared to that of the pure material. The tests demonstrated that nanodispersion of phyllosilicate layers improved the mechanical behavior of the polymers analyzed, especially the annealed sPS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4957–4963, 2006
Radiation effect on the thermal conductivity and diffusivity of ramie fibers in a range of low temperatures by γ rays
Authors: Yamanaka Atsuhiko , Izumi Yoshinobu , Terada Takaya , Ema Kimiko , Tsutsumi Masayuki , Nakamura Muneatsu , Oohazama Takeshi , Kitagawa Tooru , Fujishiro Hiroyuki , Abe Shunzo , Nishijima Shigehiro 
Published: March 2006

AbstractTo understand the influence on the thermal conductivity by the length of the molecular chain in the polymer fiber, the thermal conductivity and thermal diffusivity of ramie fibers and those irradiated by γ rays, which induced molecular chain scission of cellulose, were investigated in a range of low temperatures. The degrees of polymerization, crystallinities, and orientation angles of ramie fibers and those irradiated by γ rays (γ‐ray treatment) were measured by the solution viscosity method, solid‐state NMR, and X‐ray diffraction. Only the degree of polymerization decreased with the γ‐ray treatment, and the crystallinities and orientation angles were almost independent of the γ‐ray treatment. The thermal conductivities of the ramie fibers with and without γ‐ray treatments decreased with decreasing temperature. The thermal diffusivities of the ramie fibers and those irradiated by γ rays were almost constant from 250 to 100 K, increased slightly with the temperature decreasing from 100 to 50 K, and increased rapidly with the temperature decreasing below 50 K. The thermal conductivity and thermal diffusivity of the ramie fibers decreased with the γ‐ray treatment. The mean free path of the phonon in the ramie fibers was reduced by the γ‐ray treatment. This decrease of the thermal diffusivity and thermal conductivity was explained by the reduction of the mean free path of the phonon by molecular chain scission with γ rays. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5007–5018, 2006
Relaxation time, activation energy, and reaction pathway determination of the poly(ethylene glycol dimethacrylate)–dopant (I2) interaction with the nuclear magnetic resonance technique
Authors: Ramelow Ulku S. , Braganza Samantha N. , Ramelow Gerald J. , Darbeau Ron W. 
Published: March 2006

AbstractConductive polymers were obtained with a new polymerization method in which UV light was used as a photochemical initiator. In a previous work, optimum irradiation times were determined to obtain high conversion percentages. The effect of dopants on the conductivity of the polymer poly(ethylene glycol dimethacrylate) (PEGDM) was studied with LiClO4 and I2 as a dopant. The most effective dopant concentration was determined by the measurement of conductivities. Through the tracing of the conductivity change at various temperatures during the reaction of PEGDM with the dopant, the activation energies of the interactions were calculated, and a method was developed to follow the kinetics of the polymerization reaction with a conductometric technique. This work presents a nuclear magnetic resonance (NMR) study of the same polymer prepared under the optimum conditions with the results obtained in a previous study. NMR spectroscopy was used to determine the relaxation time, rate constants, and activation energy of the polymer–dopant interactions. As a preliminary study, pyruvic acid was used, and for acid‐catalyzed pyruvic acid/water reactions, the relaxation time, activation energy, and enthalpy change values (ΔH) were determined. With the same NMR technique, the reaction mechanisms of the polymerization, relaxation times, and rate constants of the polymer–dopant interactions were determined. The polymerization pathway was determined with NMR spectra; the results were confirmed by the calculation of the activation energies and bond‐breaking energies. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:5087–5101, 2006
Development of bond strength model for FRP plates using back‐propagation algorithm
Authors: Park Do Kyong , Jang Hwasup , Ahn Namshik 
Published: March 2006

AbstractFor the flexural reinforcement of bridge and building structure, synthetic materials whose dynamic properties are superior and those containing the merit of corrosion‐proof are widely used as the substitute for a steel plate. Since FRP plate has improved bond strength owing to the fibers externally adhering to the plate, many researches regarding the bond strength improvement have been substantially performed. To search out such bond strength improvement, previous researchers had ever examined the bond strength of FRP plate through their experiment by setting up many variables. However, since the experiment for a research on the bond strength takes much of expenditure for setting up the equipment and is time‐consuming, also is difficult to be carried out, it is limitedly conducted. The purpose of this study was to develop the most suitable artificial neural network model by application of various neural network models and algorithm to the data of the bond strength experiment conducted by previous researchers. Many variables were used as input layers against bond strength: depth, width, modulus of elasticity, tensile strength of FRP plate and the compressive strength, tensile strength, and width of concrete. The developed artificial neural network model has been applied back‐propagation, and its error was learned to be converged within the range of 0.001. Besides, the process for the over‐fitting problem has been dissolved by Bayesian technique. The verification on the developed model was executed by comparison with the test results of bond strength made by other previous researchers, which was never been utilized to the learning as yet. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 5119–5127, 2006
Two‐dimensional and three‐dimensional resistivity imaging in archaeological site investigation
Authors: Papadopoulos N. G. , Tsourlos P. , Tsokas G. N. , Sarris A. 
Published: March 2006

AbstractIn this work, the application and the effectiveness of two‐ and three‐dimensional non‐linear inversion algorithms in processing and interpretation of electrical resistivity tomography (ERT) data collected from archaeological areas are investigated in the framework of a new field technique for gathering three‐dimensional pole–pole tomographic data in a relatively small amount of time using standard archaeological prospection equipment. The inversion routine, for both the two‐dimensional and the three‐dimensional case, is based on a smoothness constrained algorithm and the forward modelling calculations are carried out using two‐dimensional and three‐dimensional finite element solvers respectively. Results of combined two‐dimensional inversions (quasi‐three‐dimensional) are compared with the full three‐dimensional inversions. Comparisons are carried out in relation to the optimum survey direction of gathering the tomographic data using the pole–pole array for synthetic data arising from three‐dimensional structures commonly encountered in archaeological sites. The response of the algorithms in the presence of noisy data was also tested. The algorithms were also used in the processing of real data collected from the archaeological sites of Sikyon and Europos in Greece. The results from the synthetic and the real data indicate the superiority of the three‐dimensional inversion algorithms in processing tomographic data. The reconstructed three‐dimensional images do not suffer from the artefacts encountered in the quasi‐three‐dimensional approach, owing to the three‐dimensional nature of the archaeological features. Most importantly, both synthetic and real data results indicate that a single survey direction is adequate to produce a valid three‐dimensional subsurface image when full three‐dimensional inversion is used in contrast to the quasi‐three‐dimensional approach, which would require that two survey directions be used to obtain satisfactory results. Copyright © 2006 John Wiley & Sons, Ltd.
On Bayesian Inference for theKFunction
Authors: Bognar Matthew A. 
Published: March 2006

AbstractTheKfunction is a summary of spatial dependence in spatial point processes. In practice one observes a realization of the spatial point process, called a spatial point pattern. Although theKfunction of a spatial point process is typically unknown, several estimators of the processKfunction have been put forth. These estimators, however, are based upon empirical averages; the complicated distributional properties of the estimators unfortunately complicates interval estimation. In this paper, we propose a Bayesian inferential framework, allowing inference for theKfunction of the spatial point process (including interval estimation). Of particular interest is the unique use of the posterior predictive distribution to (efficiently) enable such inferences. To demonstrate our technique, the well known Swedish pine sapling data (Strand, 1972) is analyzed, including a discussion on evaluating model fit. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of membrane‐attached biofilms using surfactants
Authors: Splendiani Antonietta , Livingston Andrew G. , Nicolella Cristiano 
Published: March 2006

AbstractThe effect of surfactants on membrane‐attached biofilms (MABs) was studied in a lab‐scale extractive membrane bioreactor (EMB). Twenty‐two surfactants were screened for their potential of increasing the cell wall negative charge (i.e. the electrostatic repulsion between bacteria) of Burkholderia sp. JS150 bacterial strain. Surfactants resulting in increased bacterial negative charge were further investigated for their effects on MAB population morphology and MAB attachment behaviour. Microscopic investigation of the bacterial population in MABs showed that surfactants affect the development of flagella, suggesting changes in the attachment capability of the JS150 strain in the presence of different surfactants. Among the screened surfactants, teepol showed the best characteristics in relation to the reduction of MAB accumulation, and it was tested in an EMB system for the extraction of monochlorobenzene from a synthetic wastewater. Comparison with a control EMB, operated without surfactants under the same conditions, proved that teepol effectively reduces MAB accumulation on the membrane walls. As a result, the overall mass transfer coefficient in the presence of teepol was 53% higher than in the control EMB. © 2006 Wiley Periodicals, Inc.
A long‐term stable and adjustable osmotic pump for small volume flow based on principles of phloem loading
Authors: Ehwald M. , Adleff H. , Geggier P. , Ehwald R. 
Published: March 2006

AbstractAn adjustable pump for microfluidics employing principles of osmoregulation analogous to those of phloem loading in plant leaves has been constructed and tested. Volume flow arises in a hollow fibre with vapour‐permeable hydrophobic membrane. The fibre is connected to a source chamber filled with salt crystals and saturated salt solution. The source chamber takes up water through a relatively small membrane area and delivers saturated salt solution to one end of the capillary flow path within the hollow fibre. A stationary osmotic gradient is sustained in the hollow fibre lumen by constant input of saturated salt solution and radial osmotic water absorption. The strong temperature dependence of isothermal membrane distillation enables adjustment of the flow rate up to 20 nL/s. The pump provides pulse‐free flow of any liquid with constant rate for at least 26 days without recharging the source chamber. Backpressures up to 1 bar decrease the flow rate by less than 4%. The volume delivered at a constant rate is more than 40 times larger than the volume of the source chamber. Osmoregulatory pumps of the described type may be useful for microinfusion, microdialysis and analytical microsystems. © 2006 Wiley Periodicals, Inc.
Simultaneous expression and maturation of the iron‐sulfur protein ferredoxin in a cell‐free system
Authors: Boyer Marcus E. , Wang Chia‐Wei , Swartz James R. 
Published: March 2006

AbstractThe model iron‐sulfur (Fe‐S) protein ferredoxin (Fd) from Synechocystis sp. PCC 6803 has been simultaneously produced and matured in a cell‐free production system. After 6 h of incubation at 37°C, Fd accumulated to >450 µg/mL. Essentially all was soluble, and 85% was active. Production and maturation of the protein in the cell‐free system were found to be dependent in a coupled manner on the concentration of the supplemented iron and sulfur sources, ferrous ammonium sulfate and cysteine, respectively. The recombinant expression of ISC helper proteins during cell extract preparation did not increase cell‐free Fd accumulation or activity, although the efficiency of iron and cysteine utilization increased. Fd maturation was independent of protein production rate, and proceeded at a constant rate throughout the period of active translation. In addition, incubation of denatured apo Fd with cell‐free reaction components resulted in recovery of Fd activity, supporting the interpretation that maturation mechanisms did not act co‐translationally. Incubation at 28°C increased total and active protein accumulation, but decreased the ratio of active to total Fd produced. In summary, the high product yields and folding efficiency make the cell‐free system described here an attractive platform for the study of Fe‐S protein production and maturation. The system enables both small‐volume, high throughput investigations as well as larger scale production. To our knowledge, this is the first demonstration of directed, high‐yield production and maturation of an Fe‐S protein in a cell‐free system. © 2006 Wiley Periodicals, Inc.
Reactive oxygen species induced by shear stress mediate cell death in Bacillus subtilis
Authors: Sahoo Susmita , Rao K. Krishnamurthy , Suraishkumar G.K. 
Published: March 2006

AbstractExposure of Bacillus subtilis to a shear rate of 1,482/s leads to a rapid loss of cell viability after 10 h of growth. Biochemical and molecular evidences provided below strongly suggest that cell death under high shear results from an apoptosis‐like process similar to that described in eukaryotes, with activation of a caspase‐3‐like protease (C3LP) followed by DNA fragmentation. Shear stress leads to an increase in specific intracellular reactive oxygen species (siROS), possibly through activation of NADH oxidase (NOX). The formation of siROS precedes the activation of C3LP and DNA fragmentation, thus establishing siROS as the molecular link between shear stress and apoptosis‐like cell death. A model is proposed in which NOX is viewed as being strategically placed on the plasma membrane of B. subtilis that senses and converts a mechanical force arising from shear stress into a chemical signal leading to activation of C3LP, DNA fragmentation, and thus, apoptosis‐like cell death. © 2006 Wiley Periodicals, Inc.
Engineering of Pichia pastoris for improved production of antibody fragments
Authors: Gasser Brigitte , Maurer Michael , Gach Johannes , Kunert Renate , Mattanovich Diethard 
Published: March 2006

AbstractThe methylotrophic yeast Pichia pastoris has been used for the expression of many proteins, including antibody fragments. However, limitations became obvious especially when secreting heterodimeric Fab fragments. Up‐to‐date, antibody fragments have only been expressed under control of the strong inducible alcohol oxidase 1 (AOX1) promoter, which may stress the cells by excessive transcription. Here, we examined the secretion characteristics of single chain and Fab fragments of two different monoclonal anti‐HIV1 antibodies (2F5 and 2G12) with both the AOX1 and the glyceraldehyde‐3‐phosphate dehydrogenase (GAP) promoter. Also, the influences of different secretion leaders and strains were evaluated. Interestingly, secretion was only achieved when using the GAP promoter and the Saccharomyces cerevisiae mating factor α (MFα leader), whereas there was no difference between the two P. pastoris strains. During fed batch fermentation of a 2F5 Fab expressing strain, intracellular retention of Fab heavy chains was observed, while both intact Fab and single light chain molecules were only detected in the supernatants. This led to the conclusion that protein folding and heterodimer assembly in the ER are rate limiting steps in Fab secretion. To alleviate this limitation, S. cerevisiae protein disulfide isomerase (PDI) and the unfolded protein response (UPR) transcription factor HAC1 were constitutively overexpressed in P. pastoris. While the overexpression of HAC1 led to a moderate increase of Fab secretion of 1.3‐fold, PDI enabled an increase of the Fab level by 1.9‐fold. Hence, the formation of interchain disulfide bonds can be seen as a major rate limiting factor to Fab assembly and subsequent secretion. © 2006 Wiley Periodicals, Inc.
Broth conditions determining specific cake resistance during microfiltration of Bacillus subtilis
Authors: Graves Kevin , Rozeboom Glenn , Heng Meng , Glatz Charles 
Published: March 2006

AbstractThe effects of broth pH, pressure, temperature, and fermentation medium on specific cake resistance were studied for dead‐end microfiltration of Bacillus subtilis. Decreases in pH and transmembrane pressure decreased the specific cake resistance for cells grown in both complex and defined media. With the complex medium, the reduction in resistance with temperature decrease did not offset the flux decrease caused by the increase in viscosity. The greatest decrease in specific cake resistance occurred with adjustment of pH to 7.5 for cells grown in defined medium. For those cells the change in pH resulted in aggregation leading to a large increase in flux. © 2006 Wiley Periodicals, Inc.