bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of molecular structure on extrudate swell behavior for different thermoplastic melts in an electro‐magnetized die
Authors: Sombatsompop N. , Uawongsuwan P. , Chaochanchaikul K. 
Published: February 2007

AbstractThe extrudate swell ratio of five different thermoplastic melts flowing in a constant shear rate rheometer having a capillary die with and without application of magnetic field was studied. The effects of the magnetic flux direction and density, die temperature, and wall shear rate on the extrudate swell and flow properties were investigated. The experimental results suggested that an increasing wall shear rate increased the swelling ratio for the polystyrene (PS), LLDPE, and PVC melts, but the opposite effect was observed for the ABS and PC melts. The extrudate swell ratio for the PS, ABS, PC, and LLDPE melts decreased with increasing die temperature, the effect being reversed for the PVC melt. Thermoplastic melts having high benzene content in the side‐chain and exhibiting anisotropic character were apparently affected by the magnetic field, the extrudate swell ratio increasing with magnetic flux density. The effect of the magnetic field on the extrudate swell ratio decreased in the order of PS → ABS → PC. The extrudate swell ratio for the co‐parallel magnetic field system was slightly higher than that for the counter‐parallel magnetic field system at a high magnetic flux density. POLYM. ENG. SCI., 47:270–280, 2007. © 2007 Society of Plastics Engineers.
Flexural properties of surface reinforced wood/plastic deck board
Authors: Jiang Long , Wolcott Michael P. , Zhang Jinwen , Englund Karl 
Published: February 2007

AbstractDecking and railing is the largest and fastest growing market for wood–plastic composites (WPCs). Despite WPC's advantages in comparison to lumber, its modulus and creep resistance need to be further improved for demanding structural applications. In this study, WPC deck boards were reinforced by the composite sheets made of commingled glass and polypropylene fiber. Various reinforcement arrangements were carried out to identify the optimal one. Scanning electron microscopy revealed good bonding at the reinforcement/WPC interface. All reinforced samples exhibited considerably increased modulus of rupture, modulus of elasticity, and strain at break. The creep resistance of the reinforced WPC boards was also greatly improved. Creep strain was simulated with Findley's model. Master curves of creep compliance were generated by time–temperature–stress superposition principle. The Prony series was found to be the analytical expression of the master curves with acceptable accuracy. With improved mechanical properties, the reinforced WPC board can be used in more demanding applications. POLYM. ENG. SCI., 47:281–288, 2007. © 2007 Society of Plastics Engineers.
Preform shape and operating condition optimization for the stretch blow molding process
Authors: Thibault F. , Malo A. , Lanctot B. , Diraddo R. 
Published: February 2007

AbstractIn this work, a new design approach was developed to automatically and consecutively predict optimal preform geometry and optimal operating conditions for the stretch blow molding process. The numerical approach combines a constrained gradient‐based optimization algorithm that iterates automatically over predictive finite element software. The strategy allows for targeting a specified container thickness distribution by manipulating consecutively the preform geometry (thickness and shape) and the operating parameters subject to process and design constraints. For the preform shape optimization, the preform geometry is mathematically parameterized for simplified treatment and the corresponding sensitivities are evaluated using a finite difference technique. A finite difference technique is also employed for the operating condition optimization. The constrained optimization algorithms are solved via the use of the sequential quadratic programming method that updates the design variables accordingly. Predicted optimization results obtained on an industrial case are presented and discussed to assess the validity when compared to experimental results and the robustness of the proposed approach. POLYM. ENG. SCI., 47:289–301, 2007. © 2007 Society of Plastics Engineers.
Polybutadiene rubber/organoclay nanocomposites: Effect of organoclay with various modifier concentrations on the vulcanization behavior and mechanical properties
Authors: Kim Min‐Su , Kim Gue‐Hyun , Chowdhury Subhendu Ray 
Published: February 2007

AbstractIt has been reported that the cure time t90, scorch time t2, and their difference (t90−t2) of Polybutadiene rubber (BR)/organoclay nanocomposites were much reduced over those of BR. This effect can be attributed to the ammonium groups in the organoclay. The possible formation of a Zn complex in which sulfur and ammonium modifier participate may facilitate the formation of crosslinks. If this assumption is true, it is expected that the organoclay with higher ammonium modifier concentration will give larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. The effect of organoclay with different modifier concentration on the vulcanization behavior and mechanical properties of BR/organoclay hybrid was investigated in this study. As expected, the order of the torque difference was BR/Cloisite 15A > BR/Cloisite 10A > BR/Cloisite 20A > BR/Cloisite 25A > BR/Cloisite 30B > BR/Cloisite Na+, and the order of vulcanization rate also showed similar trends. The organoclay with higher modifier concentration gave larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. POLYM. ENG. SCI., 47:308–313, 2007. © 2007 Society of Plastics Engineers.
Mechanical properties of methacylic acid/acrylonitrile copolymer foam
Authors: Tie‐Min Liu , Guang‐Cheng Zhang , Ting Chen , Xue‐Tao Shi , Cui Zhang 
Published: February 2007

AbstractTo gain a foam plastic with excellent mechanical properties, tensile mechanical properties of methacylic acid/acrylonitrile (MAA/AN) copolymer and the corresponding foam microstructure were studied, and furthermore effects of the density, heat treatment, and crosslinking agent on foam mechanical properties were also discussed in this paper. The results reveal that the tensile strength and modulus of the copolymer after heat treatment are 64 MPa and 4.2 GPa respectively, when compared with 58 MPa and 3.8 GPa before heat treatment respectively. Foam mechanical properties are enhanced with the rise of the density, and the values tested accords with the theoretical values of pentagonal dodecahedron mechanical model basically. Foam mechanical properties are enhanced via heat treatment, and the same result can be observed after using the crosslinking agent (acrylamide) too. All these results indicate that MAA/AN copolymer foam possesses excellent mechanical properties, such as its tensile, 10% compressive and shear strength are 1.3, 0.8, and 0.8 MPa respectively when the foam density is 52 kg/m3. POLYM. ENG. SCI., 47:314–322, 2007. © 2007 Society of Plastics Engineers.
Poly(butylene terephthalate)/poly(ε‐caprolactone) blends: Miscibility and thermal and mechanical properties
Authors: Di Lorenzo Maria Laura , Pietra Paola La , Errico Maria Emanuela , Righetti Maria Cristina , Angiuli Marco 
Published: February 2007

AbstractMiscibility and thermal and mechanical properties of poly(butylene terephthalate) (PBT) blends with poly(ε‐caprolactone) (PCL) were analyzed as a function of the molecular mass of PCL. It was found that the components are miscible when oligomeric PCL is blended with PBT, probably due to favorable interactions between OH end groups of poly(ε‐caprolactone) and ester groups of PBT. In the blends containing high molar mass PCL, the concentration of hydroxyl end groups is lower, allowing only partial miscibility of the components. The resulting materials display good mechanical properties, with enhanced performance at rupture compared to plain PBT. POLYM. ENG. SCI., 47:323–329, 2007. © 2007 Society of Plastics Engineers.
‘Bricks and mortar’ nanoparticle self‐assembly using polymers
Authors: Arumugam Palaniappan , Xu Hao , Srivastava Sudhanshu , Rotello Vincent M 
Published: February 2007

AbstractDevelopments in self‐assembly methods allow access to hierarchical materials featuring a wide range of functionality and applications. Polymer‐based self‐assembly of nanoparticles opens up new avenues for the fabrication of highly structured nanocomposites that can serve as bridges between ‘bottom‐up’ and ‘top‐down’ methods. Of various interactions leading to self‐assembly of nanocomposites, hydrogen bonding and electrostatic interactions are commonly utilized. In this review, we illustrate the design and subsequent property tuning of various self‐assembled nanocomposite materials that were developed based on these interactions. Copyright © 2007 Society of Chemical Industry
Synthesis and characterization of new nanocomposites based on epoxy resins and organophilic clays
Authors: Gârea Sorina‐Alexandra , Iovu Horia , Stoleriu Stefania , Voicu Georgeta 
Published: February 2007

AbstractEpoxy–clay nanocomposites were synthesized using different types of modified montmorillonite, either with a classic quaternary ammonium salt or with protonated adducts synthesized by reacting resorcinol diglycidyl ether with monoamines (benzylamine or cyclohexylamine). The chemical structure was investigated using Fourier transform infrared and 1H NMR spectrometry. The nanocomposite structures were confirmed using X‐ray diffraction analysis and transmission electron microscopy. The influence of the montmorillonite modifier on the glass transition temperature of the cured composites was studied using dynamic mechanical analysis. Copyright © 2007 Society of Chemical Industry
Is the intrinsic disorder of proteins the cause of the scale‐free architecture of protein–protein interaction networks?
Authors: Schnell Santiago , Fortunato Santo , Roy Sourav 
Published: February 2007

AbstractIn protein–protein interaction (PPI) networks certain topological properties appear to be recurrent: network maps are considered scale‐free. It is possible that this topology is reflected in the protein structure. In this paper, we investigate the role of protein disorder in the network topology. We find that the disorder of a protein (or of its neighbors) is independent of its number of PPIs. This result suggests that protein disorder does not play a role in the scale‐free architecture of protein networks.
Proteomic analysis of the oxidative stress response inCandida albicans
Authors: Kusch Harald , Engelmann Susanne , Albrecht Dirk , Morschhäuser Joachim , Hecker Michael 
Published: February 2007

AbstractAn efficient oxidative stress response (OSR) is important for the facultative pathogenic yeastCandida albicansto survive within the human host. We used a large scale 2‐D protein gel electrophoresis approach to analyze the stress response mechanisms ofC. albicansafter treatment with hydrogen peroxide and the thiol oxidizing agent, diamide. Quantitation ofin vivoprotein synthesis after pulse labeling of the proteins with radioactiveL‐[35S]‐methionine resulted in characteristic proteome signatures for hydrogen peroxide and diamide with significant overlap of 21 up‐regulated proteins for both stressors. Among the induced proteins were enzymes with known antioxidant functions like catalase or thioredoxin reductase and a set of oxidoreductases. 2‐D gel analysis of mutants in theCAP1gene revealed that the synthesis of 12 proteins is controlled by the oxidative stress regulator Cap1p. Stressing its importance for theC. albicansOSR, all 12 proteins were also induced after oxidative challenge by hydrogen peroxide or diamide.
Kinetics of hexene‐1 polymerization using [(N,N′‐diisopropylbenzene)‐2,3‐(1,8‐napthyl)‐1,4‐diazabutadiene] dibromonickel/methylaluminoxane catalyst system
Authors: Subramanyam Ummadisetty , Sivaram Swaminathan 
Published: February 2007

AbstractKinetics of hexene‐1 polymerization was investigated using [(N,N′‐diisopropylbenzene)2,3‐(1,8‐napthly)‐1,4‐diazabutadiene]dibromonickel/methylaluminoxane catalyst. Experiments were performed at varying catalyst and monomer concentrations in the temperature range of −10 to 35 °C. First order time‐conversion plot shows a downward curvature at temperatures of 20 °C and 35 °C indicating the presence of finite termination reactions. A nonlinear plot of degree of polymerization (Pn) with respect to conversion indicates occurrence of transfer reactions and slow initiation. The experimental molar masses are higher than predicted, which implies that a fraction of catalyst species could not be activated or is deactivated at the early stages of the reactions. The efficiency of the catalyst (Cateff) varies from 0.77 to 0.89. The observed polydispersity of the poly(hexene‐1) s is in the range of 1.18–1.48. The reaction order was found to be 1.11 with respect to catalyst. The Arrhenius plot obtained using the overall propagation rate constant, kp, at five different temperatures (−10, 0, 10, 20, and 35 °C) was found to be linear with an activation energy, Ea = 4.3 kcal/mol. Based on the results presented it is concluded that the polymerization of hexene‐1 under the above‐mentioned conditions shows significant deviation from ideal “living” behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1093–1100, 2007
Dynamical behavior of the vascular endothelial growth factor: Biological implications
Authors: Horta Bruno A. C. , Cirino José J. V. , de Alencastro Ricardo B. 
Published: February 2007

AbstractThe vascular endothelial growth factor (VEGF) seems to be the most important regulator of physiological and pathological angiogenesis, being, for this reason, a favorite target for therapies against angiogenesis‐related diseases. VEGF is a homodimer in which the monomers are formed by β‐strands interconnected on the poles by three loops. A recent work showed that an intimate relationship between loops‐1 and ‐3 is required for high affinity binding to the receptors (Kiba et al., J Biol Chem 2003;278:13453–13461). In this work, we report the results of a 10‐ns molecular dynamics simulation of VEGF. We analyzed the dynamical behavior of the protein (using a dynamical cross‐correlation map) and found that it is governed by a high degree of correlation between the motions of the loops. We also performed a principal component analysis and found an overall motion in which the opposite poles are projected against each other, just like the movement of the wings of a butterfly. From the biological point of view, it is likely that this motion would facilitate receptor binding since VEGF must enter a restricted cavity formed by the two subunits of the receptor. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Predicting disulfide connectivity patterns
Authors: Lu Chih‐Hao , Chen Yu‐Ching , Yu Chin‐Sheng , Hwang Jenn‐Kang 
Published: February 2007

AbstractDisulfide bonds play an important role in stabilizing protein structure and regulating protein function. Therefore, the ability to infer disulfide connectivity from protein sequences will be valuable in structural modeling and functional analysis. However, to predict disulfide connectivity directly from sequences presents a challenge to computational biologists due to the nonlocal nature of disulfide bonds, i.e., the close spatial proximity of the cysteine pair that forms the disulfide bond does not necessarily imply the short sequence separation of the cysteine residues. Recently, Chen and Hwang (Proteins 2005;61:507–512) treated this problem as a multiple class classification by defining each distinct disulfide pattern as a class. They used multiple support vector machines based on a variety of sequence features to predict the disulfide patterns. Their results compare favorably with those in the literature for a benchmark dataset sharing less than 30% sequence identity. However, since the number of disulfide patterns grows rapidly when the number of disulfide bonds increases, their method performs unsatisfactorily for the cases of large number of disulfide bonds. In this work, we propose a novel method to represent disulfide connectivity in terms of cysteine pairs, instead of disulfide patterns. Since the number of bonding states of the cysteine pairs is independent of that of disulfide bonds, the problem of class explosion is avoided. The bonding states of the cysteine pairs are predicted using the support vector machines together with the genetic algorithm optimization for feature selection. The complete disulfide patterns are then determined from the connectivity matrices that are constructed from the predicted bonding states of the cysteine pairs. Our approach outperforms the current approaches in the literature. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Wind structure over the sea
Authors: Westwater F. L. 
Published: February 2007

AbstractA comparison between theory and observation is made for he problem of veer of wind with height over the sea. Observations made in H.M.ships, notably aircraft carriers, which may be assumed to be at least as accurate as shore based observations are included. Frequency diagrams for the angle of veer show peculiar features which are absent from land observations. It is suggested that the motion of the sea surface mobility is discussed. for this, and the general effect of surface mobility is discussed.In view of the uniformity of the surface and the absence of marked thermal effects, one would expect good agreement between theory and observation in the case of wind structure in the friction layer over the sea. unfortunately the agreement is, if anything, less good than over the land, and the sea observations show certain interesting features which are absent in the case of land observations.It has been the practice in the past to attribute much of the disparity between theory and observation over the sea to observational difficulties. The difficulty of making pilot balloon observations “from a moving steamer” is mentioned by Rossby, and others seek refuge in the fact that wind directions at the surface are only measured to the nearest compass point. The probable validity of these objections in the past is not denied, but the recent rapid development of the Naval meteorological Service, and the growing volume of sea observations of a high standard of accuracy collected by trained observers calls for a review of the situation. Surface winds in H.M. ships are no longer measured n points, but in degrees, allowance for the relative motion of the ship being made automatically. An occasion when great accuracy in measurement of wind direction is possible is when aircraft are being flown off or on to the deck of a carrier. Furthermore pilot balloon observations are not, in general, more difficult to carry out on board than on shore. Ships of the size of aircraft carriers do not move a great deal in winds of less than force six, and the instruments available for following the balloon are superior to those used on shore, although they cannot be described here for obvious reasons. It may be taken as certain that observations taken on one of the larger carriers are at least as accurate as any taken ashore provided the wind is of force five or less. In the discussion below, observations from carriers will be given, as well be given, as well as those from merchant ships.
The ozone content of surface air and its relation to some meteorological conditions
Authors: Glückauf E. 
Published: February 2007

AbstractThe variations of the ozone content of surface air during depressions have been investigated. Three definite conditions were found to occur, apparently without exception.A drop in the ozone content is found up to 300 miles in advance of warm fronts, with high values of ozone after their passage.An occluded front of the warm front type behaved in exactly the same way as a front with a warm sector.A drop in the ozone content is found after the passage of backbent occlusions, persisting until the front has moved on up to 200 miles, after which the ozone returns to its normal concentration.This seems to indicate that the observed change under these conditions in the ozone content is due to the increased stability of air not at the surface but at the upper warm front inversion. This would prevent the ozone (constantly destroyed near the ground) from being restored by turbulent interchange with air from greater heights.
Structural analysis of O‐glycopeptides employing negative‐ and positive‐ion multi‐stage mass spectra obtained by collision‐induced and electron‐capture dissociations in linear ion trap time‐of‐flight mass spectrometry
Authors: Deguchi Kisaburo , Ito Hiroki , Baba Takashi , Hirabayashi Atsumu , Nakagawa Hiroaki , Fumoto Masataka , Hinou Hiroshi , Nishimura Shin‐Ichiro 
Published: February 2007

AbstractStructural analyses of various glycans attached to proteins and peptides are highly desirable for elucidating their biological roles. An approach based on mass spectrometry (MS) combining both collision‐induced dissociation (CID) and electron‐capture dissociation (ECD) in the positive‐ and negative‐ion modes has been proposed as a simple and direct method of assigning an O‐glycan without releasing it from the peptide and of determining the amino acid sequence of the peptide and glycosylation site. The instrument used is an electrospray ionization (ESI) linear ion trap (LIT) time‐of‐flight (TOF) mass spectrometer with tandem LITs for CID by He gas and ECD. The proposed approach was tested with two synthetic O‐glycopeptides binding a sialyl Lewis x (sLex) oligosaccharide and a 3′‐sialyl N‐acetyllactosamine (3′‐SLN) on a serine (S) residue. In the negative‐ion mode, the CID MS2 spectra of O‐glycopeptides showed a relatively abundant glycoside‐bond cleavage between the core N‐acetylglucosamine (GlcNAc) and serine (S) that yields deprotonated C3‐type fragment ions of O‐glycan and deprotonated Z0‐type peptide ions. The structure of the sLex (3′‐SLN) oligosaccharide was simply assigned by comparing the CID MS3 spectrum derived from the C3‐type fragment ion with the CID MS2 spectra of the sLex and sLea (3′‐ and 6′‐SLN) standards (i.e., negative‐ion MSn spectral matching). The amino acid sequence of the peptide including the glycosylation site was determined from the ECD MS2 spectrum in the positive‐ion mode. Copyright © 2007 John Wiley & Sons, Ltd.
Concurrent quantification of light and heavy sulphur volatiles in wine by headspace solid‐phase microextraction coupled with gas chromatography/mass spectrometry
Authors: Fedrizzi Bruno , Magno Franco , Moser Sergio , Nicolini Giorgio , Versini Giuseppe 
Published: February 2007

AbstractA new method based on headspace solid‐phase microextraction coupled with gas chromatography/mass spectrometry (HS‐SPME‐GC/MS) to analyse 13 light and heavy volatile sulphur compounds in the same run was established. For the successful application of the procedure, various adsorption process parameters were optimised. In particular the nature of the adsorptive phase, the temperature, the ionic strength of the sample solutions and the equilibration time were considered. The best extraction conditions, in terms of the maximum signal obtainable for each compound, were obtained with a carboxen‐polydimethylsiloxane‐divinylbenzene (CAR‐PDMS‐DVB) 2 cm long coating fibre. The choice of suitable internal standards and the matrix effect were studied and the proposed method was validated by determining linearity, precision and accuracy, evaluating the critical, detection and quantification limits. This method is fast, sensitive and precise and easy to transfer to wine quality control. Finally, the proposed method was applied to the determination of the aforementioned sulphur compounds in 32 red and white wines. Copyright © 2007 John Wiley & Sons, Ltd.