bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polylactide/nano‐ and micro‐scale silica composite films. II. Melting behavior and cold crystallization
Authors: Huang Jiann‐Wen , Chang Hung Yung , Wen Ya‐Lan , Kang Chiun‐Chia , Yeh Mou‐Yung 
Published: February 2009

AbstractNonisothermal crystallization of polylactide (PLA)/silica composites prepared by (i) directly blending the PLA with nanoscale colloidal silica sol and by (ii) a sol–gel process are studied by differential scanning calorimeter (DSC) at various heating rates. Samples quenched from the molten state exhibited two melting endotherms (Tml and Tmh) due to melt‐recrystallization during the DSC scans. Lower heating rate and the presence of silica particles generate a lower peak intensity ratio of Tml /Tmh. The nonisothermal crystallization kinetics is analyzed by modified Avrami model, Ozawa model, and Liu‐Mo models. The modified Avrami and Liu‐Mo models successfully described the nonisothermal cold crystallization processes, but Ozawa is inapplicable. The nucleation constant (Kg) is calculated by modified Lauritzen‐Hoffman equation and the activation energy by Augis‐Bennett, Kissinger, and Takhor models. These calculated parameters indicate consistently that the nanoscale silica particles seem to form more heterogeneous nucleation to increase crystallization, but microscale one form hindrance to retard crystallization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of polyurethane elastomers based on chitosan and poly(ε‐caprolactone)
Authors: Barikani Mehdi , Honarkar Hengameh , Barikani Majid 
Published: February 2009

AbstractBiodegradable polyurethane (PU) elastomers with potential for biomedical and industrial applications were synthesized by the reaction of poly(ε‐caprolactone) (PCL) and isophorone diisocyanate (IPDI), extended with different mass ratio of chitosan and 1,4‐butane diol (BDO). Their chemical structures were characterized using FTIR, 1HNMR, and 13CNMR, and thermal properties were determined by TGA and DMTA. Incorporation of chitosan contents into the polyurethane backbone caused improvement in thermal stability and thermal degradation rate. Optimum thermal properties and degradation profile were obtained from elastomer extended with chitosan. The crystallinity and hydrophilicity of the prepared polymers were also examined by X‐ray and contact angle measurements. The results showed that hydrophilicity decreased and crystallinity increased with increasing of chitosan content in polyurethane backbone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Investigation of nanostructure and properties of aromatic–aliphatic polyamide‐based nanocomposites with clay additives
Authors: Zulfiqar Sonia , Shabbir Saima , Ishaq Muhammad , Sarwar Muhammad Ilyas 
Published: February 2009

AbstractAromatic–aliphatic polyamide/clay nanocomposites were produced using solution intercalation technique. Surface modification of the clay was performed with ammonium salt of aromatic diamine and the polyamide chains were produced by condensation of 4‐aminophenyl sulfone with sebacoyl chloride (SCC) in dimethyl acetamide. Carbonyl chloride endcapped polymer chains were prepared by adding extra SCC near the end of polymerization reaction. The nanocomposites were investigated for organoclay dispersion, water absorption, mechanical, and thermal properties. Formation of delaminated and intercalated nanostructures was confirmed by X‐ray diffraction and TEM studies. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (8 wt %). Thermal stability and glass transition temperatures of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. The amount of water uptake for these materials decreased as compared with the neat polyamide. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structure and properties of new thermoforming bionanocomposites based on chitin whisker‐graft‐polycaprolactone
Authors: Feng Liangdong , Zhou Ziyan , Dufresne Alain , Huang Jin , Wei Ming , An Lijia 
Published: February 2009

AbstractThermoformable bionanocomposites of chitin whisker‐graft‐polycaprolactone (CHW‐g‐PCL) were synthesized by initiating the ring‐opening polymerization of caprolactone monomer onto the CHW surface under microwave radiation. In this case, the “graft from” strategy contributed to long and dense “plasticizing” PCL tails onto the CHW surface as the key of thermoforming, and, therefore, such bionanocomposites were injection‐molded as the sheets with a structure of cocontinuous phase mediated with the entanglement of grafted PCL chains. The structure and properties of the molded CHW‐g‐PCL sheets were investigated by FTIR, XRD, SEM, DSC, DMTA, contact angle measurement, and tensile test. With an increase of the PCL content in CHW‐g‐PCL, the strength and elongation as well as the hydrophobicity of the nanocomposites increased at one time. This is the first report on the thermoformable polymer‐grafted nanocrystal derived from natural polysaccharide. Moreover, such new bionanocomposites with good mechanical performances could have great potential applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Studies on the complexation between generation‐4.5 methyl ester‐terminated poly(amidoamine) dendrimer and Pd2+ ions in methanol
Authors: Lu Wenting , Li Guoping , Luo Yunjun , Jin Yujuan 
Published: February 2009

AbstractPoly(amidoamine) (PAMAM) dendrimers have attracted attention because of their well‐defined molecule structures and chemical versatility, which also complicate the mechanism of interactions between metal ions and PAMAM dendrimers. To further understand the complexation of dendrimers with metal ions, the interactions between Pd2+ ions and G4.5‐COOCH3 PAMAM dendrimers were investigated by UV‐vis and FTIR spectrophotometric method. The results show that the addition of K2PdCl4 results in covalent attachment of the PdCl alcoholysis product of this complex to tertiary amines within the dendrimers under the appropriate conditions. This process was also supported by X‐ray photoelectron spectroscopy data of the new complex which indicated a 1 : 3 Pd/Cl ratio. The maximum loading of 80 Pd2+ ions within the G4.5‐COOCH3 dendrimers and the best pH value of 8.3 for complexation system are also obtained. Details regarding the Pd species present in solution of different chemical environments are reported. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Preparation and characterization of venlafaxine hydrochloride‐loaded chitosan nanoparticles and in vitro release of drug
Authors: Shah Sunil , Pal Angshuman , Kaushik V. K. , Devi Surekha 
Published: February 2009

AbstractThe venlafaxine hydrochloride (VHL)‐loaded chitosan nanoparticles were prepared by ionic gelation of chitosan (CS) using tripolyphosphate (TPP). The nanoparticles were characterized using FTIR, differential scanning calorimetry, X‐ray diffraction, dynamic light scattering, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The effect of concentration of CS, polyethylene glycol (PEG), VHL and CS/TPP mass ratio on the particle size and zeta potential of nanoparticles was examined. The particle size of CS/TPP nanoparticles and VHL‐loaded CS/TPP nanoparticles was within the range of 200–400 nm with positive surface charge. In the case of VHL‐loaded nanoparticles and PEG‐coated CS/TPP nanoparticles, the particle size increases and surface charge decreases with increasing concentration of VHL and PEG. Both placebo and VHL‐loaded CS/TPP nanoparticles were observed to be spherical in nature. PEG coating on the surface of CS/TPP nanoparticles was confirmed by XPS analysis. Maximum drug entrapment efficiency (70%) was observed at 0.6 mg/mL drug concentration. In vitro drug release study at 37°C ± 0.5°C and pH 7.4 exhibited initial burst release followed by a steady release. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Immobilization of manganoporphyrin on a novel polymeric support and catalytic oxidation characteristic of supported catalyst
Authors: Gao Baojiao , Wang Ruixin , Zhang Yan 
Published: February 2009

AbstractMonomer glycidyl methacrylate (GMA) was grafted on silica gel particles in the manner of “grafting from,” and the grafted particles PGMA/SiO2 was prepared. The grafted particles PGMA/SiO2 is a kind of novel support for the immobilization of metalloporphyrin catalysts. In the presence of basic catalysts, the ring‐opening reaction of the epoxy groups of the grafted PGMA occurred and the bonding of meso‐tetra (4‐hydroxylphenyl) porphyrin (THPP) on the particles PGMA/SiO2 was realized, resulting in the bonded particles HPP‐PGMA/SiO2. Subsequently, the metallation of the bonded particles HPP‐PGMA/SiO2 was carried out via the coordination reaction between HPP‐PGMA/SiO2 and manganese salt, resulting in the supported manganoporphyrin (MnP) catalyst MnP‐PGMA/SiO2. The supported catalyst was used in the catalytic oxidation of ethyl benzene into acetophenone by molecular oxygen. In this article, the effects of various factors such as the species and amount of the catalyst on the bonding process of THPP were studied because of the importance of the bonding reaction of THPP in the preparation of the catalyst MnP‐PGMA/SiO2. Finally, the catalytic performance of MnP‐PGMA/SiO2 in the catalytic oxidation process of ethyl benzene was investigated. The experimental results show that triethylamine is a suitable catalyst for the bonding of THPP on the grafted particles PGMA/SiO2 and for the forming of MnP‐PGMA/SiO2. The supported catalyst MnP‐PGMA/SiO2 can effectively activate molecular oxygen, and obviously catalyze the oxidation process of ethyl benzene to acetophenone by molecular oxygen. It was found that the immobilization density of MnP on MnP‐PGMA/SiO2 has a great effect on the catalytic activity of the catalyst. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparison of chemical and enzymatic emulsion polymerization of styrene
Authors: Kwon Hyuk‐Sung , Chung Eunyong , Lee Dong‐Ig , Lee Chang‐Ha , Ahn Ik‐Sung , Kim Ju‐Young 
Published: February 2009

AbstractFor the reasonable comparison of chemical and enzymatic polymerization, manganese(III) acetate and manganese peroxidase (MnP)‐catalyzed synthesis of polystyrenes were chosen and studied with respect to the yield and the polydispersity of polymer particles. MnP allowed the production of polystyrene in a higher yield and higher polydispersity (82.34% and 2.61) than manganese(III) acetate (77.90% and 1.75). This is believed to be due to a gradual supply of initiator radicals via a catalytic cycle in MnP‐catalyzed polymerization, whereas radicals are generated all at once in Mn(III)‐mediated polymerization. NMR spectroscopy revealed that atactic polystyrene was produced by emulsion polymerization using Mn(III) or MnP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Substituent effect on the optoelectronic properties of poly(p‐phenylenevinylene) based conjugated‐nonconjugated copolymers
Authors: Palai Akshaya K. , Rath Sangram K. , Srivastava Ritu , Kamalasanan Modeeparampil Narayanan , Patri Manoranjan 
Published: February 2009

AbstractTwo classes of light emitting Poly(p‐phenylenevinylene) (PPV) based conjugated‐nonconjugated copolymers (CNCPs) have been synthesized. The conjugated chromophores containing 2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene (MEHPV) and 2,5‐dimethyl‐1,4‐phenylenevinylene (DMPV) moieties are rigid segments and nonconjugated portion containing hexyl units are flexible in nature. All copolymers were synthesized by well‐known Wittig reaction between the appropriate bisphosphonium salts and the dialdehyde monomers. The resulting polymers were found to be readily soluble in common organic solvents like chloroform, THF and chlorobenzene. The effect of chromophore substituents on the optical and redox properties of the copolymers has been investigated. Color tuning was carried out by varying the molar percentage of the comonomers. The UV‐Vis absorption and PL emission of the copolymers were in the range 314–395 nm and 494–536 nm respectively. All the polymers show good thermal stability. Polymer light‐emitting diodes (PLEDs) were fabricated in ITO/PEDOT:PSS/emitting polymer/cathode configurations of selected polymers using double‐layer, LiF/Al cathode structure. The emission maxima of the polymers were around 499–536 nm, which is a blue‐green part of the color spectrum. The threshold voltages of the EL polymers were in the range of 5.4–6.2 V. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Polyvinylidene fluoride‐based novel polymer electrolytes for magnesium‐rechargeable batteries with Mg(CF3SO3)2
Authors: Aravindan Vanchiappan , Karthikaselvi G. , Vickraman P. , Naganandhini S. P. 
Published: February 2009

AbstractMagnesium trifluoromethanesulfonate (Mg (CF3SO3)2)‐based polymer electrolytes (PEs) have been prepared with polyvinylidene fluoride (PVdF) as a host matrix. Tetraglyme and tetrabutyl ammonium chloride (TBACl) were used as plasticizer and filler, respectively, in the matrix by solution‐casting technique. The electrolyte containing 5 wt % TBACl exhibits the conductivity of 0.442 mS cm−1 at ambient temperature. X‐ray diffraction study reveals the amorphous nature of the PE. Linear sweep voltammetry was also performed to evaluate the decomposition potential of the electrolyte. The morphological features were analyzed by scanning electron microscope. The activation energy has also been calculated, which corroborates the ionic conductivity results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effects of the incorporation of low‐molecular‐weight diurethanes on thermal and rheological properties of thermoplastic polyurethane
Authors: Fiorio Rudinei , Zattera Ademir José , Ferreira Carlos Arthur 
Published: February 2009

AbstractIn this study, two low‐molecular‐weight diurethanes were synthesized and blended with thermoplastic polyurethane (TPU). The effects of the incorporation on the thermal and rheological properties of TPU were evaluated. The diurethanes were obtained from the reaction of 4,4′‐diphenylmethane‐diisocyanate (MDI) with 1‐butanol (Additive 1) or 1‐octanol (Additive 2). Blending of the additives with TPU was carried out in a torque rheometer, and the blends obtained were analyzed by differential scanning calorimetry (DSC), torque rheometry, and capillary rheometry. The torque rheometry showed that an increase in the amount of both additives displaced the charging peaks to longer times and reduced the torque values after melting. The DSC analysis showed that the incorporation of the additives did not affect the glass transition temperature (Tg) of the flexible phase of TPU. However, an increase in the amount of Additive 1 led to a reduction in the Tg of the rigid phase, while increasing the amount of Additive 2 caused an increase in the Tg of this phase. Capillary rheometry results showed that blends with up to 2 wt % of additive led to intrinsic viscosity and melt‐flow stability values higher than those of processed TPU. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The representation of national political freedom on Web interface design: The indicators
Authors: Li Rowena 
Published: February 2009

AbstractThis study is designed to validate 10 Power Distance indicators identified from previous research on cultural dimensions to establish a measurement for determining a country's national political freedom represented on Web content and interface design. Two coders performed content analysis on 156 college/university Web sites selected from 39 countries. One‐way analysis of variance was applied to analyze each of the proposed 10 indicators to detect statistical significant differences among means of the three freedom groups (free‐country group, partly‐free‐country group, and not‐free‐country group). The results indicated that 6 of the 10 proposed indicators could be used to measure a country's national political freedom on Web interface design. The seventh indicator, symmetric layout, demonstrated a negative correlation between the freedom level and the Web representation of Power Distance. The last three proposed indicators failed to show any significant differences among the treatment means, and there are no clear trend patterns for the treatment means of the three freedom groups. By examining national political freedom represented on Web pages, this study not only provides an insight into cultural dimensions and Web interface design but also advances our knowledge in sociological and cultural studies of the Web.
Question types in public libraries' digital reference service in Finland: Comparing 1999 and 2006
Authors: Numminen Piritta , Vakkari Pertti 
Published: February 2009

AbstractThis study analyzes to which degree the question types addressed to a digital reference service run by a consortium of public libraries have changed between the Years 1999 and 2006. The data consist of representative samples of reference questions to a Finnish “Ask a Librarian” digital reference service in the years studied. Questions were classified based on a taxonomy refining earlier major taxonomies. The proportion of ready reference questions had increased from 33 to 45% whereas the proportion of subject‐based research questions had decreased from 57 to 47%. Among the former, fact‐finding questions had especially increased, and among the latter, topical search questions had decreased. These changes in the popularity of question types are likely related to the way people are searching on the Internet. It is concluded that the Internet has somewhat reduced the traditional role of public libraries in mediated topical searching.
Comparative effects of interferon alpha‐2b and pegylated interferon alpha‐2b on menstrual cycles and ovarian hormones in cynomolgus monkeys
Authors: Enright Brian P. , Compton David R. , Collins Nathaniel , Davis Thomas , McIntyre Barry S. 
Published: February 2009

AbstractBACKGROUND: The covalent modification of interferon (IFN) α2b with monomethyoxy polyethylene glycol (PEG) reduces its clearance rate and increases its half‐life. High doses of interferon (IFN) α2b have previously been shown to affect maintenance of pregnancy in rhesus monkeys. Given the role of ovarian hormones in reproductive function and pregnancy, this study was conducted to assess the effects of PEG‐IFNα2b or IFNα2b (comparative control) on ovarian hormones and menstrual cyclicity in cynomolgus monkeys. In addition, the potential for reversibility of PEG‐IFNα2b or IFNα2b‐related observations was assessed. METHODS: Monkeys were administered 3,105 µg/m2 human recombinant (hr) IFNα2b or 52, 262, or 4,239 µg/m2 PEG‐hr‐IFNα2b every other day for one menstrual cycle, followed by a post‐dose period of up to two menstrual cycles. RESULTS: Monkeys administered 3,105 µg/m2 hr‐IFNα2b or 52, 262, or 4,239 µg/m2 PEG‐hr‐IFNα2b exhibited transient decreases in food consumption, leukocyte and erythrocyte parameters. Monkeys administered 3,105 µg/m2 hr‐IFNα2b exhibited lengthened menstrual cycles that were associated with a delay in reaching peak ovarian hormone levels and lower respective peak concentrations. Similarly, monkeys administered 4,239 µg/m2 PEG‐hr‐IFNα2b exhibited lengthened menstrual cycles and a delay in reaching peak ovarian hormone levels and slightly lower respective peak concentrations. Post‐dosing menstrual cycle length, estradiol and progesterone profiles exhibited evidence of recovery in both the hr‐IFNα2b and the high‐dose PEG‐hr‐IFNα2b groups. CONCLUSIONS: Administration of hr‐IFNα2b or PEG‐hr‐IFNα2b at high doses to cynomolgus monkeys resulted in similar effects on menstrual cycles, estradiol and progesterone profiles, and exhibited evidence of reversibility upon cessation of dosing. These results suggest that the previously observed high‐dose IFNα‐related effects on the maintenance of pregnancy in monkeys are likely the result of altered ovarian function. Birth Defects Res (Part B) 86:29‐39, 2009. © 2009 Wiley‐Liss, Inc.
Comparing four different approaches for the determination of inter‐residue interactions provides insight for the structure prediction of helical membrane proteins
Authors: Gao Jun , Li Zhijun 
Published: February 2009

AbstractStudying inter‐residue interactions provides insight into the folding and stability of both soluble and membrane proteins and is essential for developing computational tools for protein structure prediction. As the first step, various approaches for elucidating such interactions within protein structures have been proposed and proven useful. Since different approaches may grasp different aspects of protein structural folds, it is of interest to systematically compare them. In this work, we applied four approaches for determining inter‐residue interactions to the analysis of three distinct structure datasets of helical membrane proteins and compared their correlation to the three individual quality measures of structures in these datasets. These datasets included one of 35 structures of rhodopsin receptors and bacterial rhodopsins determined at various resolutions, one derived from the HOMEP benchmark dataset previously reported, and one comprising of 139 homology models. It was found that the correlation between the average number of inter‐residue interactions obtained by applying the four approaches and the available structure quality measures varied quite significantly among them. The best correlation was achieved by the approach focusing exclusively on favorable inter‐residue interactions. These results provide interesting insight for the development of objective quality measure for the structure prediction of helical membrane proteins. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 547–556, 2009.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Design and implement a virtual learning architecture for troubleshooting practice of automotive chassis
Authors: Liang Janus S. 
Published: February 2009

AbstractIn this research, a web‐based troubleshooting architecture of automobile chassis is constructed, and it can support distance learning of practical courses in automotive chassis repair and maintenance. This system allows remote learners to operate a practical training module for troubleshooting through the Internet. There are several subjects discussed in this research: (1) developing the learning contents for repairing automotive chassis; (2) building the virtual and interactive platform for browsing and practice of troubleshooting; (3) creating the online evaluation tools and effectiveness analysis. The framework has been tested and implemented in the course, “Automotive Practice: Chassis,” in the Department of Mechanical Engineering at Yung‐Ta Institute of Technology and Commerce during the spring semester of 2005. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 512–525, 2010; View this article online atwileyonlinelibrary.com; DOI 10.1002/cae.20219
Downer‐to‐Riser Coupling Technique for Petroleum Refining
Authors: Wu C. , Cheng Y. , Jin Y. 
Published: February 2009

AbstractMany recent developments in the fluid catalytic cracking (FCC) technique have focused on achieving cleaner gasoline with less olefins and maximizing light olefins such as propylene. A coupled high‐density downer‐to‐riser reactor was proposed to utilize the advantages of both downer and riser to improve the gasoline quality and to efficiently control the product distribution. The basic idea is to decompose the complex FCC reactions into two reaction zones with distinct operating conditions. The downer accommodates high‐severity operation at the initial stage with the benefit of near plug‐flow while the riser is operated at a lower temperature with longer contacting time to promote hydrogen shift reactions. A comprehensive 2D reactor model is presented to predict the reactor performances for different reactor designs. The coupled downer‐to‐riser reactor design was found to have more light olefins and cleaner gasoline than the conventional riser and the coupled riser‐to‐riser reactor design.