bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and antimicrobial activity of Konjac Glucomannan modified with quaternary ammonium compound
Authors: Lei Wanxue , Yang Qinhuan , Jia Xingang , Zhang Tingyou 
Published: July 2010

AbstractSeven kind of graft copolymerization Konjac Glucomannan with quaternary ammonium group have been prepared, using Konjac Glucomannan (KGM) and methacryloxylethyl alkyl dimethyl ammonium bromide with c8–c18 alkyl and benzyl in water, ceric ammonium nitrate as initiator, the reaction temperature of 348 K, and the reaction period of 3 h. The structures were confirmed by FTIR. The 15 min inhibitory rates of all the graft copolymerization KGM against Escherichia coli and Staphylococcus aureus reached 99.99%, against Candida albicans somewhat lower, but 30 min inhibitory rate still reached 99.02% for graft copolymerization KGM with quaternary ammonium group having 14 alkyl. The antibacterial mechanism of the graft copolymerization KGM has been investigated by adsorption ability to E. coli, measure of 260 nm absorbing materials and SEM micrographs. Firstly, the bacteria were fastly adsorbed by graft copolymerization KGM. Interactions between bacterial membranes and antibacterial product cause fundamental changes in both membrane structure and function, induced leakage of cytoplasmic contents is a classic indication of damage to the bacterial cytoplasmic membrane. The loss of the connection between the outer membrane and the underlying peptidoglycan induces the abnormality of nodular structures and bleb formation of the cell envelope of E. coli. The antibacterial mechanism is in accordance with microbiologic findings identifying surface blebbing as the first morphologic change occurring in the permeability barrier of gram‐negative bacteria under mild heat stress and laser irradiation, etc. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Properties of compression‐molded plates made from wood powders impregnated with liquefied wood‐based novolak‐type phenol‐formaldehyde resins
Authors: Lee Wen‐Jau , Wu Yun‐Hsuan , Wu Chiou‐Chang , Chang Kuo‐Chun , Tseng I‐Min 
Published: July 2010

AbstractNovolak‐type phenol‐formaldehyde (PF) resins with solution form were prepared by reacting phenol‐liquefied Cryptomeria japonica (Japanese cedar) wood with formalin in the presence of methanol. Wood powders of Albizzia falcate (Malacca albizzia) impregnated with these resins were air dried followed by an oven‐dried at 60°C. DSC analysis showed the PF resin existing in wood powders could be melted, and could be cured if hexamine was mixed and heated at high temperature. Compression‐molded plates made with PF resin impregnated woods had a high degree of curing reaction. However, compression‐molded plates hot‐pressed at 180°C for 8 min or 200°C for 5 min had better internal bonding strength and dimensional stability than others. Premixing hexamine with PF resin and impregnating into wood powders simultaneously could enhance the reactivity of PF resin, but it was not useful for improving the properties of compression‐molded plates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Highly purified natural rubber by saponificaion of latex: Analysis of green and cured properties
Authors: Amnuaypornsri Sureerut , Sakdapipanich Jitladda , Tanaka Yasuyuki 
Published: July 2010

AbstractNatural rubber (NR) was purified by saponification of fresh latex from Hevea brasiliensis and soaking process of the coagulum with aqueous NaOH solution. This treatment resulted in the decrease of nitrogen content to the same level as enzymatic deproteinized NR. The saponification of NR latex and soaking of the coagulum gave the rubber having good processability with easy to cure. The saponified rubber showed outstanding physical and dynamic mechanical properties such as high tensile properties, high storage modulus, low tan δ, low heat build‐up and low dynamic compression set. The saponified rubber blend with styrene butadiene rubber (SBR) according to the recipe of rubber tire showed also a good performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Radiation processing and characterization of poly(vinyl alcohol) nano‐composites, Part 1: Nano‐particulate filler tuned crosslinking behavior
Authors: Dubey Kumar A. , Chaudhari Chandrasekhar V. , Rao Rekha , Bhardwaj Yatender K. , Goel Narender K. , Sabharwal Sunil 
Published: July 2010

AbstractNano‐composites of poly vinyl alcohol containing different nano‐fillers namely multiple walled carbon nanotubes (MWNT), single walled carbon nanotubes (SWNT), silica nanoparticles, and silver nanoparticles were prepared by sonication‐assisted solution mixing and subjected to different doses of gamma radiation. The efficacy of radiation crosslinking was analyzed by sol–gel analysis, Charlesby‐Pinner parameter estimation and crosslinking density measurements. Crosslinking of nano‐composites was found to increase with radiation dose and markedly affected with the type of nano‐particulate filler in the matrix (po/qo in the range: 0.40–0.83). The results have been explained on the basis of Raman spectroscopy, hydrodynamic volume measurements, contact angle measurements, and scanning electron microscopy (SEM). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Evaluation effects of biobased plasticizer on the thermal, mechanical, dynamical mechanical properties, and permanence of plasticized PVC
Authors: Benaniba Mohamed Tahar , Massardier‐Nageotte Valérie 
Published: July 2010

AbstractSunflower oil (SO) is a renewable resource that can be epoxidized, and the epoxidized SO has potential uses as an environmentally friendly in polymeric formulations, especially for poly (vinyl chloride) (PVC). Epoxidized sunflower oil (ESO) was prepared by treating the oil with peracetic acid generated in situ by reacting glacial acetic acid with hydrogen peroxide. Epoxidation was confirmed using spectroscopic and titration methods. ESO was used as a coplasticizer in PVC for the partial replacement of di‐(2‐ethyl hexyl) phthalate (DEHP). The effect of ESO on the thermal stability of plasticized PVC was evaluated by using synmero scale for the sheets. In presence of ESO plasticized PVC samples showed a reduction in discoloration and the number of conjugated double bonds. By using thermogravimetry, the incorporation of 15/45 of ESO/DEHP in PVC presents the lowest weight loss. The results of the shore hardness and mechanical properties showed that a proportion of DEHP could be substituted by ESO. By use of DMA, the formulation which contains 25 % wt of ESO in plasticizer system shifts the glass transition temperature (Tg) to ambient temperature. The migration phenomenon was studied on PVC based samples plasticized with DEHP and ESO in varying amounts. The migration was monitored by the weight loss percentage of the samples immersed into n‐hexane or heated in an oven. The amount of extracted or volatilized DEHP is proportional to the added ratio of ESO in plasticizer system. All of this favored the partial replacement of DEHP by ESO as biobased plasticizer for flexible PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Novel polymeric flocculants based on polyacrylamide grafted dextran in kaolin suspension
Authors: Krishnamoorthi S. , Adhikary P. , Mal D. , Singh R. P. 
Published: July 2010

AbstractA study is done on ceric‐ammonium‐nitrate (CAN) initiated graft copolymerization of polyacrylamide (PAM) on to dextran (Dx) by solution polymerization technique. The average molecular weight of dextran is 7.0 × 10−6 g/mole. By changing the concentrations of the initiator in the reaction feed, a series of graft copolymer (Dx‐g‐PAM1 to Dx‐g‐PAM4) with variation in the number and length of the grafted PAM chains are obtained. The flocculation characteristics of various polymers are investigated by the use of settling tests in 2 wt % using kaolin suspensions. Among the series of graft copolymers, the one with highest molecular weight shows superior performance. The flocculation characteristics of the best‐performing graft copolymer (Dx‐g‐PAM3) are compared with those of various commercially available flocculants and PAM in the kaolin suspension. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Amphiphilic PEG‐based ether‐anhydride terpolymers: Synthesis, characterization, and micellization
Authors: Zhao Aijun , Zhou Qi , Chen Tao , Weng Jie , Zhou Shaobing 
Published: July 2010

AbstractA series of amphiphilic poly(ether‐anhydrides) terpolymers composed of sebacic acid, 1,3‐bis(carboxyphenoxy) propane, and poly(ethylene glycol) (PEG) were synthesized via melt‐condensation polymerization. The resultant terpolymers were characterized by 1H‐nuclear magnetic resonance spectroscopy (1H‐NMR), Fourier transform infrared spectroscopy, gel permeation chromatography, X‐ray diffraction, polarization optical microscope, differential scanning calorimeter, and water contact angle. Biodegradable micelles were prepared via a precipitation method through self‐emulsification. The shape of these micelles was uniform and spheric according to the atomic force microscopy and transmission electron microscopy images. The dynamic light scattering measurements indicated that the diameters of micelles were typically in the range of 118–359 nm. The results displayed the PEG‐based ether‐anhydride terpolymers may be of great potential as nanoscaled carriers for drug delivery system. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Isothermal crystallization kinetics and crystal structure of poly(lactic acid): Effect of triphenyl phosphate and talc
Authors: Xiao H. W. , Li Peng , Ren Xiaomin , Jiang Tao , Yeh Jen‐Taut 
Published: July 2010

AbstractIn this article, kinetics of neat poly(lactic acid) (PLA) and its blends with triphenyl phosphate (TPP) and/or talc crystallized isothermally in the temperature range of 113–128°C was analyzed by differential scanning calorimetry (DSC) and described by the Avrami equation. The results showed that the average value of Avrami exponents n is around 2.0 for neat PLA and the PLA/15TPP blend, and around 3.0 for the PLA/1.2Talc blend and the PLA/15TPP/1.2Talc blend. The crystallization rate constants k for neat PLA and its blends were increased in the following order: the PLA/15TPP blend, neat PLA, the PLA/15TPP/1.2Talc blend, and PLA/1.2Talc blend. The half‐time of crystallization t1/2 was increased with an increase of crystallization temperature Tc and the presence of TPP, and was decreased sharply with the incorporation of talc. Further investigation into crystallization activation energy ΔEa of neat PLA and its blends with 15 wt % TPP and/or 1.2 wt % talc showed that the values of ΔEa were increased with the incorporation of TPP and/or talc compared to that of neat PLA. It was verified by wide angle X‐ray diffraction (WAXD) that neat PLA and its blends with TPP and/or talc crystallized isothermally in the temperature range of 113–128°C, and all formed the α‐form crystal after enough annealing time. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Retrieval effectiveness of machine translated queries
Authors: Dolamic Ljiljana , Savoy Jacques 
Published: July 2010

AbstractThis article describes and evaluates various information retrieval models used to search document collections written in English through submitting queries written in various other languages, either members of the Indo‐European family (English, French, German, and Spanish) or radically different language groups such as Chinese. This evaluation method involves searching a rather large number of topics (around 300) and using two commercial machine translation systems to translate across the language barriers. In this study, mean average precision is used to measure variances in retrieval effectiveness when a query language differs from the document language. Although performance differences are rather large for certain languages pairs, this does not mean that bilingual search methods are not commercially viable. Causes of the difficulties incurred when searching or during translation are analyzed and the results of concrete examples are explained.
Active disturbance rejection control for power plant with a single loop
Authors: Xia Yuanqing , Liu Bo , Fu Mengyin 
Published: July 2010

AbstractThe cascade proportional‐integral‐derivative (PID) control method is widely used in power plant control field. In this paper, an active disturbance rejection control (ADRC) for a power plant with a single loop is introduced for eliminating the shortcomings of the cascade PID control method. The proposed controller based on the ADRC method consists of a tracking differentiator (TD), an extended state observer (ESO) and a nonlinear combination of errors. In this approach, the processes with higher orders, uncertainties and unmodeled dynamics are viewed as lower‐ordered systems with general disturbances, and the general disturbances are estimated by ESO, and then actively compensated. Besides, only one measured output is needed in the proposed method instead of two or three in the cascade PID control method. Some simulation studies compared with the regular cascade PID control method show the proposed method has better performance beyond the regular cascade PID control method.Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Peroxidase activity of bacterial cytochrome P450 enzymes: Modulation by fatty acids and organic solvents
Authors: Rabe Kersten S. , Erkelenz Michael , Kiko Kathrin , Niemeyer Christof M. 
Published: July 2010

AbstractThe modulation of peroxidase activity by fatty acid additives and organic cosolvents was determined and compared for four bacterial cytochrome P450 enzymes, thermostable P450 CYP119A1, the P450 domain of CYP102A1 (BMP), CYP152A1 (P450bsβ), and CYP101A1 (P450cam). Utilizing a high‐throughput microplate assay, we were able to readily screen more than 100 combinations of enzymes, additives and cosolvents in a convenient and highly reproducible assay format. We found that, in general, CYP119A1 and BMP showed an increase in peroxidative activity in the presence of fatty acids, whereas CYP152A1 revealed a decrease in activity and CYP101A1 was only slightly affected. In particular, we observed that the conversion of the fluorogenic peroxidase substrate Amplex Red by CYP119A1 and BMP was increased by a factor of 38 or 11, respectively, when isopropanol and lauric acid were present in the reaction mixture. The activity of CYP119A1 could thus be modulated to reach more than 90% of the activity of CYP152A1 without effectors, which is the system with the highest peroxidative activity. For all P450s investigated we found distinctive reactivity patterns, which suggest similarities in the binding site of CYP119A1 and BMP in contrast with the other two proteins studied. Therefore, this study points towards a role of fatty acids as activators for CYP enzymes in addition to being mere substrates. In general, our detailed description of fatty acid‐ and organic solvent‐effects is of practical interest because it illustrates that optimization of modulators and cosolvents can lead to significantly increased yields in biocatalysis.
Ensembles of signal transduction models using Pareto Optimal Ensemble Techniques (POETs)
Authors: Song Sang Ok , Chakrabarti Anirikh , Varner Jeffrey D. 
Published: July 2010

AbstractMathematical modeling of complex gene expression programs is an emerging tool for understanding disease mechanisms. However, identification of large models sometimes requires training using qualitative, conflicting or even contradictory data sets. One strategy to address this challenge is to estimate experimentally constrained model ensembles using multiobjective optimization. In this study, we used Pareto Optimal Ensemble Techniques (POETs) to identify a family of proof‐of‐concept signal transduction models. POETs integrate Simulated Annealing (SA) with Pareto optimality to identify models near the optimal tradeoff surface between competing training objectives. We modeled a prototypical‐signaling network using mass‐action kinetics within an ordinary differential equation (ODE) framework (64 ODEs in total). The true model was used to generate synthetic immunoblots from which the POET algorithm identified the 117 unknown model parameters. POET generated an ensemble of signaling models, which collectively exhibited population‐like behavior. For example, scaled gene expression levels were approximately normally distributed over the ensemble following the addition of extracellular ligand. Also, the ensemble recovered robust and fragile features of the true model, despite significant parameter uncertainty. Taken together, these results suggest that experimentally constrained model ensembles could capture qualitatively important network features without exact parameter information.
Lipase‐catalyzed dimethyl adipate synthesis: Response surface modeling and kinetics
Authors: Chaibakhsh Naz , Rahman Mohd Basyaruddin Abdul , Basri Mahiran , Salleh Abu Bakar , Abd‐Aziz Suraini 
Published: July 2010

AbstractDimethyl adipate (DMA) was synthesized by immobilized Candida antarctica lipase B‐catalyzed esterification of adipic acid and methanol. To optimize the reaction conditions of ester production, response surface methodology was applied, and the effects of four factors namely, time, temperature, enzyme concentration, and molar ratio of substrates on product synthesis were determined. A statistical model predicted that the maximum conversion yield would be 97.6%, at the optimal conditions of 58.5°C, 54.0 mg enzyme, 358.0 min, and 12:1 molar ratio of methanol to adipic acid. The R2 (0.9769) shows a high correlation between predicted and experimental values. The kinetics of the reaction was also investigated in this study. The reaction was found to obey the ping‐pong bi‐bi mechanism with methanol inhibition. The kinetic parameters were determined and used to simulate the experimental results. A good quality of fit was observed between the simulated and experimental initial rates.
Microbial 1‐butanol production: Identification of non‐native production routes and in silico engineering interventions
Authors: Ranganathan Sridhar , Maranas Costas D. 
Published: July 2010

AbstractThe potential of engineering microorganisms with non‐native pathways for the synthesis of long‐chain alcohols has been identified as a promising route to biofuels. We describe computationally derived predictions for assembling pathways for the production of biofuel candidate molecules and subsequent metabolic engineering modifications that optimize product yield. A graph‐based algorithm illustrates that, by culling information from BRENDA and KEGG databases, all possible pathways that link the target product with metabolites present in the production host are identified. Subsequently, we apply our recent OptForce procedure to pinpoint reaction modifications that force the imposed product yield in Escherichia coli. We demonstrate this procedure by suggesting new pathways and genetic interventions for the overproduction of 1‐butanol using the metabolic model for Escherichia coli. The graph‐based search method recapitulates all recent discoveries based on the 2‐ketovaline intermediate and hydroxybutyryl‐CoA but also pinpointes one novel pathway through thiobutanoate intermediate that to the best of our knowledge has not been explored before.
Lentivirus‐mediated knockdown of aggrecanase‐1 and ‐2 promotes chondrocyte‐engineered cartilage formation in vitro
Authors: Wang Zheng‐Hui , Yang Zhuang‐Qun , He Xi‐Jing , Kamal B. Elnour , Xing Zhe 
Published: July 2010

AbstractChondrocyte‐based tissue engineering has emerged as a promising approach for repair of injured cartilage tissues that have a poor self‐healing capacity. However, this technique faces a major limitation: dedifferentiation of chondrocytes occurs following several passages in culture. Aggrecan, a major component of cartilage extracellular matrix, plays an essential role in chondrocyte differentiation. The aim of this study is to determine whether inhibition of chondrocyte aggrecanases, key degradative enzymes for aggrecan in cartilage, could benefit chondrocyte differentiation and the preservation of chondrocyte phenotype within a long‐term period. Lentivirus‐mediated RNA interference (RNAi) was employed to target both aggrecanase‐1 and ‐2 in primary rat chondrocytes, and the transduced cells were seeded into chitosan–gelatin three‐dimensional scaffolds. Histological, morphological, and biochemical analyses were performed at 1–8 weeks post‐implantation to study chondrocyte survival, differentiation, and function. We found that lentivirus‐mediated RNAi notably decreased the abundance of aggrecanase transcripts in chondrocytes but did not affect cell viability. Most importantly, compared to the control constructs seeded with untransduced chondrocytes, the aggrecanase inhibition increased chondrocyte proliferation and reinforced the production of glycosaminoglycans and total collagen, indicative of chondrocyte differentiation. The mRNA expression of chondrocyte marker genes (collagen II and aggrecan) was enhanced by aggrecanase silencing relative to the control. Together our data demonstrate that inhibition of endogenous aggrecanases facilitates chondrocyte differentiation and chondrocyte‐engineered cartilage formation in vitro. The combination of lentiviral delivery system and genetic manipulation techniques provides a useful tool for modulation of chondrocyte phenotype in cartilage engineering. Biotechnol. Bioeng. 2010;107:730–736. © 2010 Wiley Periodicals, Inc.
Improved specific productivity in cephalexin synthesis by immobilized PGA in silica magnetic micro‐particles
Authors: Bernardino Susana M.S.A. , Fernandes Pedro , Fonseca Luís P. 
Published: July 2010

AbstractThere is a marked trend in pharmaceutical industry towards the replacement of classical organic methods by “green” alternatives that minimize or eliminate the generation of waste and avoid, where possible, the use of toxic and/or hazardous reagents and solvents. In this work the kinetically controlled synthesis of cephalexin by soluble and penicillin G acylase immobilized in sol–gel micro‐particles with magnetic properties was performed in aqueous media with PGME and 7‐ADCA as substrates, at different concentrations of substrate, temperature, pH, enzyme to substrate ratio and acyl donor to nucleophile ratio. Excess acyl donor had a strong effect on cephalexin productivity. A PGME/7‐ADCA ratio of 3 was considered optimum. A maximum specific productivity of $5.9\,{\rm mmol}\,{\rm h}^{ - 1} \,{\rm g}_{{\rm biocatalyst}}^{ - 1} $ at 160 mM 7‐ADCA, 480 mM PGME and low enzyme to substrate ratio at 32.5 U mmol−1 7‐ADCA was obtained with immobilized PGA in full aqueous medium, suggesting that diffusional limitations were minimized when compared with other commercial biocatalysts. A half‐life of 133 h for the immobilized biocatalyst was estimated during cephalexin synthesis in the presence of 100 mM 7‐ADCA and 300 mM PGME, in 50 mM Tris/HCl at pH 7.2 and 14°C. These results compare quite favorably with those previously reported for the kinetically controlled synthesis of cephalexin. Biotechnol. Bioeng. 2010;107: 753–762. © 2010 Wiley Periodicals, Inc.