bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of heat transfer in rotational molding
Authors: Banerjee S. , Yan W. , Bhattacharyya D. 
Published: September 2008

AbstractRotational molding is a process for manufacturing hollow or open‐sided plastic products using a rotating mold subjected to heating and then cooling. The process is attractive for the production of stress‐free objects at a competitive cost. In this article, a modified model for heat transfer in rotational molding is proposed, which assumes that the heat transfer at the mold‐powder interface is because of convection, whereas the powder particles are heated up by conduction. Heat transfer through the mold–air contact is also included. A source‐based formulation is used for modeling the layer‐by‐layer nonisothermal deposition of plastic. The reduced heat transfer due to warpage is calculated by using a modified heat transfer coefficient. Good overall agreement is found between the cycle times as predicted by the model and the experimental data. The model is then used for calculating the cycle time for particulate composites, based on their effective properties. A reduction in the cycle time is observed in the case of reinforced composites. This is attributed to the increase in thermal conductivity of the particulate composites and the reduced mass fraction of the polymer. Numerical calculations of the cycle time for the glass‐bead reinforced composites are found to be in good agreement with the experimental results. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Mixed‐mode subcritical crack growth in orthotropic polymers
Authors: Wu Chunhui , Mantell Susan C. , Davidson Jane H. 
Published: September 2008

AbstractA semi‐empirical model of mixed‐mode sub‐critical crack propagation is presented for orthotropic polymers subjected to continuous loading. The model considers a combination of opening and shearing propagation modes. Optical measurement of crack propagation in an orthotropic liquid crystalline polymer film for orientation angles, which define the orientation of the loading to the extrusion direction, of 45 and 90° provides the empirical constants required by the model. The model is validated by comparison of predicted and measured crack propagation at 30, 60, and 75°. The impact of orientation angle on crack propagation is significant. A critical angle is identified at which the crack propagation rates for the opening and shearing modes are equivalent. For orientation angles less than the critical angle the crack growth is dominated by the shearing mode. For orientation angles greater than the critical angle, the crack growth is dominated by the opening mode. For the liquid crystalline polymer film tested, the critical angle is 52.6°. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Effects of polyol molecular weight on properties of benzoxazine–urethane polymer alloys
Authors: Rimdusit Sarawut , Mongkhonsi Tharathon , Kamonchaivanich Pakawan , Sujirote Kuljira , Thiptipakorn Sunan 
Published: September 2008

AbstractRecently, a new thermoset resin namely benzoxazine (BA) resin has been developed. The polymer possesses several outstanding properties, such as, ease of synthesis, low viscosity, near‐zero shrinkage, lack of by‐product upon curing, high thermal stability, and high mechanical property. Moreover, the benzoxazine resins can be alloyed with various types of resins because of the various function groups in their structure. In this work, urethane elastomer (PU) is used to enhance toughness of the polybenzoxazine. The effects of polyol molecular weights on the properties of BA: PU polymer alloys are investigated. The experiment reveals that the similar curing peaks of the matrices at various polyol molecular weights, with the same urethane mass fraction, in the resin mixtures are obtained. The glass transition temperature increases from 160°C of polybenzoxazine to 240–245°C in the 70:30 BA:PU system. In addition, the char yield increases when the higher molecular weight of polyol is added. The flexural modulus of polybenzoxazine decreases from 6.2 GPa to be in the range of 2.2–2.8 GPa when 30 wt% of PU is presented in the alloys. Furthermore, the synergism with ultimate flexural strength is observed in the 90:10 BA:PU alloy for all molecular weights of the polyol used. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Melting behavior and isothermal crystallization kinetics of nylon 11/EVOH/dicumyl peroxide blends
Authors: Wang Biaobing , Ding Zhengya , Hu Guosheng 
Published: September 2008

AbstractNylon 11/ethylene‐vinyl alcohol/dicumyl peroxide (DCP) blends were prepared using a single‐screw extruder. The melting behavior and isothermal crystallization kinetics were investigated using differential scanning calorimetry. The reorganization of nylon 11 crystals is strongly hindered owing to cocrosslinking phenomena. The analysis of the crystallization kinetics demonstrated that the Avrami equation well described the isothermal crystallization process of the primary stage. The spherulites growth kinetics parameters and fold surface free energy were also evaluated. The experimental results confirmed that the presence of DCP increased the crystallization rate. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Kinetics of the thermal decomposition reaction of diethylketone cyclic triperoxide in acetone–toluene and acetone–1‐propanol binary solvent mixtures
Authors: Iglesias Mariángeles , Eyler Nora , Cañizo Adriana 
Published: September 2008

AbstractThe thermal decomposition reaction of diethylketone triperoxide (DEKT) ca. 0.02 M was studied in binary mixtures of acetone–toluene and acetone–1‐propanol at 150 °C. Products of DEKT thermolysis in solution, detected by GC analysis, were diethylketone, bibenzyl and butane. The reactions were explored by GC at different solvent compositions and in each case the reactions followed a pseudo first order kinetic law, up to at least 90% peroxide conversion. The rate coefficient value of the reaction is affected by the solvent properties, showing an increase in the kobs values with increases in the polarity of the solvent mixture in acetone–toluene systems. Changes in the rate coefficient values are probably caused by the presence of the apolar toluene solvent, which dominates the preferential solvation around the DEKT molecule through non‐specific interactions. In acetone–1‐propanol mixtures the solvation effect is slightly dominated by the specific interactions between the 1‐propanol and a polar intermediate specie represented by the biradical, initially formed. The rate coefficient value increases ca. 6% in the mixture with 0.1 mole fraction of 1‐propanol in comparison with the value in pure acetone; but no more changes in rate coefficient values are observed when the amount of the alcohol increases. The critical state of the reaction (intermediate biradical) is preferentially solvated by the 1‐propanol instead of acetone, but in mixtures of different composition, it is not possible to detect any effect on the reactivity for homolytic rupture of the OO bond. Copyright © 2008 John Wiley & Sons, Ltd.
Fully aromatic poly(ether ketone)s bearing macrocycle pendants: Synthesis and crosslinking
Authors: Yue Xigui , Zhu Ming , Zhang Haibo , Liu Baijun , Wang Yishan , Jiang Zhenhua 
Published: September 2008

AbstractThis study reports a method to prepare fully aromatic poly(ether ketone) thermosets. The cyclization of 2′,5′‐dimethoxy[1,1′‐biphenyl]‐2,5‐diol and a difluoro monomer was carried out under pseudo high dilution condition. Two types of fully aromatic poly(ether ketone)s with macrocycle were successfully prepared by copolymerization of macrocycle of aryl ether ketone containing hydroxyphenyl groups, 4,4′‐(hexafluoroisopropylidene)diphenol (HFBPA), and 4,4‐difluorobenzophenone. The obtained copolymers have high molecular mass, good solubility, and high glass transition temperatures in the presence of CsF, the crosslinking reaction of copolymers occurred and afforded fully aromatic thermoset poly(aryl ether ketone)s by ring‐opening reaction driven by entropy. After crosslinking, these copolymers show much higher glass transition temperatures, excellent thermal stability, and better mechanical strength. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7002–7010, 2008
Aliphatic poly(ester‐carbonate)s bearing amino groups and its RGD peptide grafting
Authors: Hu Xiuli , Chen Xuesi , Xie Zhigang , Cheng Haibo , Jing Xiabin 
Published: September 2008

AbstractThis article deals with (1) synthesis of novel cyclic carbonate monomer (2‐oxo [1,3]dioxan‐5‐yl)carbamic acid benzyl ester (CAB) containing protected amino groups; (2) ring‐opening copolymerization of the cyclic monomer with L‐lactide (LA) to provide novel degradable poly(ester‐carbonate)s with functional groups; (3) removal of the protective benzyloxycarbonyl (Cbz) groups by catalytic hydrogenation to afford the corresponding poly(ester‐co‐carbonate)s with free amino groups; (4) grafting of oligopeptide Gly‐Arg‐Gly‐Asp‐Ser‐Tyr (GRGDSY, abbreviated as RGD) onto the copolymer pendant amino groups in the presence of 1,1′‐carbonyldiimidazole (CDI). The structures of P(LA‐co‐CA/RGD) and its precursor were confirmed by 1H NMR analysis. Cell experiments showed that P(LA‐co‐CA/RGD) had improved adhesion and proliferation behavior. Therefore, the novel RGD‐grafted block copolymer is promising for cell or tissue engineering applications. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7022–7032, 2008
Synthesis and self‐assembly of tadpole‐shaped organic/inorganic hybrid poly(N‐isopropylacrylamide) containing polyhedral oligomeric silsesquioxane via RAFT polymerization
Authors: Zhang Weian , Liu Li , Zhuang Xiaodong , Li Xiaohui , Bai Jinrui , Chen Yu 
Published: September 2008

AbstractAminopropylisobutyl polyhedral oligomeric silsesquioxane (POSS) was used to prepare a POSS‐containing reversible addition‐fragmentation transfer (RAFT) agent. The POSS‐containing RAFT agent was used in the RAFT polymerization of N‐isopropylacrylamide (NIPAM) to produce tadpole‐shaped organic/inorganic hybrid Poly(N‐isopropylacrylamide) (PNIPAM). The results show that the POSS‐containing RAFT agent was an effective chain transfer agent in the RAFT polymerization of NIPAM, and the polymerization kinetics were found to be pseudo‐first‐order behavior. The thermal properties of the organic/inorganic hybrid PNIPAM were also characterized by differential scanning calorimetry. The glass transition temperature (Tg) of the tadpole‐shaped inorganic/organic hybrid PNIPAM was enhanced by POSS molecule. The self‐assembly behavior of the tadpole‐shaped inorganic/organic hybrid PNIPAM was investigated by atomic force microscopy and dynamic light scattering. The results show the core‐shell nanostructured micelles with a uniform diameter. The diameter of the micelle increases with the molecular weight of the hybrid PNIPAM. Surprisingly, the micelle of the tadpole‐shaped inorganic/organic hybrid PNIPAM with low molecular weight has a much bigger and more compact core than that with high molecular weight. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7049–7061, 2008
Reducing Water Permeability while Maintaining Transparency of PET: A Plasma Immersion Ion Implantation Study
Authors: Mizuno Keisuke , Gan Bee K. , Kondyurin Alexey , Bilek Marcela M. M. , McKenzie David R. 
Published: September 2008

AbstractPET sheets were surface‐modified by ion implantation from argon, nitrogen and hydrogen plasmas. The ion implantation was found to cause carbonization and cross‐linking, improving gas barrier properties against water vapor. The barrier effectivity improved with increased implanted ion fluence. The permeability changes and optical bandgap both depend on the ion species used during implantation. The lowest permeability was obtained using argon. For practical applications, the balance between gas barrier properties and photopic transparency is important. Our results show that argon implantation yields the lowest permeability with best retention of photopic transparency.magnified image
Influence of Impinging Ion Energy on the Bonding and Mechanical Characteristics of DLC Films Deposited by Microwave ECR Plasma CVD
Authors: Singh Sujit , Pandey Mukesh , Kishore Ramaswamy , Chand Naresh , Dash Sitaram , Tyagi Ashok , Patil Dinkar 
Published: September 2008

AbstractDLC films were deposited on Si(111) substrates using CH4/Ar gas and microwave ECR plasma CVD processes. The energy of the ions impinging on the substrate during deposition was varied by changing the rf self bias voltage developed on the substrate. The bonding characteristics of the deposited films were investigated using FTIR and Raman spectroscopy, and mechanical properties were measured by nanoindentation and nanoscratch tests. The results obtained from different characterization techniques are correlated and explained on the basis of existing growth models for DLC films. Our studies indicate that the energy of the ions impinging on the substrates has a strong influence on the bonding characteristics and mechanical properties of the films.magnified image
Influence of different assignment conditions on the determination of symmetric homodimeric structures with ARIA
Authors: Bardiaux Benjamin , Bernard Aymeric , Rieping Wolfgang , Habeck Michael , Malliavin Thérèse E. , Nilges Michael 
Published: September 2008

AbstractThe ambiguous restraint for iterative assignment (ARIA) approach for NMR structure calculation is evaluated for symmetric homodimeric proteins by assessing the effect of several data analysis and assignment methods on the structure quality. In particular, we study the effects of network anchoring and spin‐diffusion correction. The spin‐diffusion correction improves the protein structure quality systematically, whereas network anchoring enhances the assignment efficiency by speeding up the convergence and coping with highly ambiguous data. For some homodimeric folds, network anchoring has been proved essential for unraveling both chain and proton assignment ambiguities. Proteins 2009. © 2008 Wiley‐Liss, Inc.
Antibacterial activity of [10]‐gingerol and [12]‐gingerol isolated from ginger rhizome against periodontal bacteria
Authors: Park Miri , Bae Jungdon , Lee Dae‐Sil 
Published: September 2008

AbstractGinger (Zingiber officinale Roscoe) has been used widely as a food spice and an herbal medicine. In particular, its gingerol‐related components have been reported to possess antimicrobial and antifungal properties, as well as several pharmaceutical properties. However, the effective ginger constituents that inhibit the growth of oral bacteria associated with periodontitis in the human oral cavity have not been elucidated. This study revealed that the ethanol and n‐hexane extracts of ginger exhibited antibacterial activities against three anaerobic Gram‐negative bacteria, Porphyromonas gingivalis ATCC 53978, Porphyromonas endodontalis ATCC 35406 and Prevotella intermedia ATCC 25611, causing periodontal diseases. Thereafter, five ginger constituents were isolated by a preparative high‐performance liquid chromatographic method from the active silica‐gel column chromatography fractions, elucidated their structures by nuclear magnetic resonance spectroscopy and electrospray ionization mass spectrometry and their antibacterial activity evaluated. In conclusion, two highly alkylated gingerols, [10]‐gingerol and [12]‐gingerol effectively inhibited the growth of these oral pathogens at a minimum inhibitory concentration (MIC) range of 6–30 µg/mL. These ginger compounds also killed the oral pathogens at a minimum bactericidal concentration (MBC) range of 4–20 µg/mL, but not the other ginger compounds 5‐acetoxy‐[6]‐gingerol, 3,5‐diacetoxy‐[6]‐gingerdiol and galanolactone. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of hyperin, isoquercitrin and quercetin on lipopolysaccharide‐induced nitrite production in rat peritoneal macrophages
Authors: Lee Sanghyun , Park Hee‐Seung , Notsu Yohko , Ban Hyun Seung , Kim Yong Pil , Ishihara Kenji , Hirasawa Noriyasu , Jung Sang Hoon , Lee Yeon Sil , Lim Soon Sung , Park Eun‐Hee , Shin Kuk Hyun , Seyama Toshio , Hong JangJa , Ohuchi Kazuo 
Published: September 2008

AbstractThe extract of the root of Acanthopanax chiisanensis Nakai is used for the treatment of inflammation. To analyse the action mechanism of this extract, the effect of hyperin (quercetin‐3‐O‐β‐d‐galactose) isolated from the ethyl acetate fraction of the root of A. chiisanensis on nitrite production and induction of inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS, 1 µg/mL)‐stimulated rat peritoneal macrophages were examined. The effect of the structurally related compounds, isoquercitrin (quercetin‐3‐O‐β‐d‐glucose) and quercetin (an aglycone of the two compounds) isolated from the extract of the leaves of Vaccinium koreanum Nakai was also examined to compare the effect. It was shown that hyperin inhibited the LPS‐induced iNOS expression and nitrite production. Of the three compounds, quercetin showed the most potent inhibitory activity. The phosphorylation of p44/42 mitogen activated protein kinase (MAPK), p38 MAPK and c‐Jun N‐terminal kinase (JNK) were also inhibited by these compounds. These findings suggested that hyperin in the extract of the root of A. chiisanensis inhibits nitric oxide (NO) production through inhibition of the expression of iNOS by attenuation of p44/p42 MAPK, p38 MAPK and JNK, and thus participates in the antiinflammatory activity of the extract. Copyright © 2008 John Wiley & Sons, Ltd.
Cytotoxic Xenicane Diterpenes from the Brown Alga Padina pavonia (L.) Gaill.
Authors: Awad Nagwa E. , Selim Mohamed A. , Metawe Hemaia M. , Matloub Azza A. 
Published: September 2008

AbstractColumn chromatography of the hexane fraction of a methanol extract of Padina pavonia (L.) Gaill. collected from the Red Sea at Hurghada, Egypt yielded 18,19‐epoxyxenic‐19‐methoxy‐18‐hydroxy‐4‐acetoxy‐6,9,13‐triene (1) and 18,19‐epoxyxenic‐18,19‐dimethoxy‐4‐hydroxy‐6,9,13‐triene (2). The isolated compounds have various antitumor activities against lung carcinoma (H460) and liver carcinoma (HepG2) human cell lines (in vitro). Copyright © 2008 John Wiley & Sons, Ltd.
In vitro effects of beetroot juice and chips on oxidative metabolism and apoptosis in neutrophils from obese individuals
Authors: Zielińska‐Przyjemska Małgorzata , Olejnik Anna , Dobrowolska‐Zachwieja Agnieszka , Grajek Włodzimierz 
Published: September 2008

AbstractOxidative stress and inflammation are involved in the development of obesity. Beetroot (Beta vulgaris var. rubra) is a food ingredient containing betalain pigments that show antioxidant activity. The in vitro effect of beetroot juice and chips on oxidative metabolism and apoptosis in neutrophils from obese individuals has been investigated. Fifteen obese women (aged 45 ± 9 years, BMI >30 kg/m2) and nine healthy controls (women, aged 29 ± 11 years, BMI = 22.2 ± 1.6 kg/m2) were examined. The investigated products were used as concentrates and after transport and digestion in an artificial gastrointestinal tract. Neutrophil oxidant production, in response to phorbol 12‐myristate 13‐acetate, was characterized by luminol‐dependent chemiluminescence and a flow cytometric dichlorofluorescin oxidation assay. Caspase‐3 activity, a marker of apoptosis, was measured by cleavage of the fluorogenic substrate Ac‐DEVD‐AMC. Neutrophils from obese individuals had a significantly higher ROS production compared with the controls (p < 0.05). Beetroot products inhibited neutrophil oxidative metabolism in a concentration‐dependent manner. Also observed were the pro‐apoptotic effects of beetroot at a concentration range of 0.1–10% in 24 h culture of stimulated neutrophils. These natural products (in both the liquid and solid state) have antioxidant and antiinflammatory capacity, and could be an important adjunct in the treatment of obesity. Copyright © 2008 John Wiley & Sons, Ltd.
Studies on the antioxidant and analgesic activities of Aztec marigold (Tagetes erecta) flowers
Authors: Bashir Samra , Gilani Anwar H. 
Published: September 2008

AbstractCommercially available Aztec marigold (Tagetes erecta) flower extract (Af.Cr) was evaluated for the in vitro antioxidant activity and in vivo analgesic effect on acetic‐acid‐induced abdominal writhing. The results revealed the presence of pronounced antioxidant potential in Aztec marigold flowers and a dose‐dependent (100 and 300 mg/kg) analgesic effect. The antioxidant and analgesic activities obtained seem to be in good accordance with the medicinal uses of Aztec marigold as an anti‐inflammatory and analgesic. Copyright © 2008 John Wiley & Sons, Ltd.
Chemical composition and antiproliferative activity of essential oil from the leaves of a medicinal herb, Schefflera heptaphylla
Authors: Li Yao‐Lan , Yeung Chung‐Man , Chiu Lawrence C. M. , Cen Ying‐Zhou , Ooi Vincent E. C. 
Published: September 2008

AbstractSchefflera heptaphylla (L.) Frodin is a medicinal herb widely used as a main ingredient of the popular health tea formulation against infections in Southern China. Twenty‐seven volatile compounds were identified by GC‐MS analysis from the essential oil obtained from the leaves of S. heptaphylla, and 17 of them belonged to monoterpenes or sesquiterpenes. The main volatile constituent in S. heptaphylla was found to be a monoterpene, β‐pinene, comprising about 22% of the total volatile components. The essential oil showed significant antiproliferative activity against three cancer cell lines, MCF‐7, A375 and HepG2 cells, with IC50 values of 7.3 µg/mL, 7.5 µg/mL and 6.9 µg/mL, respectively. The result of the cytotoxicity assay indicates that (−)‐β‐pinene and (+)‐β‐pinene (commercially available from Sigma) also possessed antiproliferative activity against the cancer cells MCF‐7, A375 and HepG2 with IC50 values ranging from 147.1 to 264.7 µm. Copyright © 2008 John Wiley & Sons, Ltd.
Inhibition of cytochrome P450 enzymes by rhein in rat liver microsomes
Authors: Tang Jing‐cheng , Yang Hua , Song Xue‐ying , Song Xiao‐hong , Yan Shu‐lian , Shao Jian‐qun , Zhang Tian‐lan , Zhang Jin‐nan 
Published: September 2008

AbstractRhein, an active ingredient extensively found in plants such as Aloe, Cassitora L., rhubarb and so on, has been used for a long time in China. Pharmacological tests revealed that rhein not only had a strong antibacterial action, but also may be useful in cancer chemotherapy as a biochemical modulator. Its therapeutic action and toxicity is still the subject of considerable research. With microsome incubation assays in vitro and HPLC methods, the inhibition of rat liver CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A enzymes by rhein were studied kinetically. The results showed the most inhibition of CYP2E1 by rhein (Ki = 10 µm, mixed); CYP3A and CYP2C9 were also inhibited by rhein, Ki = 30 µm (mixed) and Ki = 38 µm (mixed), respectively; rhein revealed some inhibition of CYP1A2 (Ki = 62 µm, uncompetitive) and CYP2D6 (Ki = 74 µm, mixed). Drug–drug interactions, especially cytochrome P450 (CYP)‐mediated interactions, cause an enhancement or attenuation in the efficacy of co‐administered drugs. Inhibition of the five major CYP enzymes observed for rhein suggested that changes in pharmacokinetics of co‐administered drugs were likely to occur. Therefore, caution should be paid to the possible drug interaction of medicinal plants containing rhein and CYP substrates. Copyright © 2008 John Wiley & Sons, Ltd.