bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of fiber organization and damage during single screw extrusion of natural fiber reinforced thermoplastics
Authors: Grande C. , Torres F. G. 
Published: April 2005

AbstractThe present work studies single screw extrusion processing for different systems of natural fiber reinforced thermoplastics. In the present study the mechanisms of fiber organization and fiber degradation have been investigated. The polymer matrix employed has been high density polyethylene (HDPE) with an MFI of 0.1. Fibers including jute and sisal have been used as discrete reinforcements with initial lengths varying from 5 to 10 mm. The extrusion process has been investigated using an open‐barrel single screw extruder. The issues of fiber distribution and bubble formation have been related to the mechanical properties of these composites, particularly tensile strength. Fiber degradation has been assessed after processing by microscopic examination of the extruder contents. The effect of the processing temperature on the level of fiber degradation is also discussed here. Fiber length after processing has been measured, and unimodal and bimodal fiber length distributions have been obtained. However, the issue of adequate sample preparation for the fiber length characterization procedure still requires further work in order to reduce the experimental error. Fiber orientation distributions have been estimated for some of the samples. It has been found that at higher processing temperatures the fibers show more alignment in the flow direction. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24:145–156, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20037
Single‐collector experiments and modeling of acoustically aided mesh filtration
Authors: Grossner Michael T. , Feke Donald L. , Belovich Joanne M. 
Published: April 2005

AbstractA model for the motion of particles driven by acoustic and hydrodynamic effects in the vicinity of a cylindrical collector has been previously reported. This trajectory model was developed to describe the essential physics that underlies an ultrasonically aided particle‐filtration process in which a porous mesh is used to capture particles two orders of magnitude smaller than the pore size. To validate this trajectory model, experiments were performed to elucidate the detailed motion of particles in the neighborhood of a single cylindrical collector. Images of 54‐μm‐diameter polystyrene particles in aqueous suspension responding to acoustic and hydrodynamic forces were analyzed. Particle trajectories, calculated using only experimentally measured parameters as model inputs, well predicted the experimental observations. Adjustment of the local magnitude of the acoustic field, which accounts for spatial nonuniformities in the field, results in improvements in the correspondence between the trajectory predictions and the experimental observations. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Pore and crosslinking structures of cotton cellulose crosslinked with DMDHEU‐maleic acid
Authors: Wang Chang , Chen Jui‐Chin , Yao Wei‐Hua , Chen Cheng‐Chi 
Published: April 2005

AbstractTwo dicarboxylic acids (maleic acid and tartaric acid) were used in conjunction with DMDHEU as the crosslinking agents to treat cotton fabric samples. The treated fabrics then were dyed with direct red 81. The results show that the values of the dye absorption, equilibrium absorption, rate constants, and the pore index of structural diffusion resistance constant for the various crosslinking agents are ranked as DMDHEU‐tartaric acid > DMDHEU‐maleic acid > DMDHEU alone at the same dyeing temperature. The activation energies for the three crosslinked fabrics are in the rank of DMDHEU > DMDHEU‐maleic acid > DMDHEU‐tartaric acid. The CL length values for the various crosslinking agent systems are in the series of DMDHEU‐tartaric acid > DMDHEU‐maleic acid > DMDHEU alone for a given number of CL/AGU. The values of the pore index of structural diffusion resistance constant and dyeing rate constant are increased with the increase of CL length. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 143–148, 2005
Cure behavior of UP/Org‐MMT/MEKP/cobalt octoate nanocomposites by the dynamic torsional vibration method
Authors: Cheng Yiyun , Chen Dazhu , Wang Chunlei , He Pingsheng 
Published: April 2005

AbstractThe cure behavior of unsaturated polyester(UP)/organo‐montmorillonite (Org‐MMT)/methyl ethyl ketone peroxide (MEKP)/cobalt octoate intercalated nanocomposites at varying temperatures and Org‐MMT loadings was investigated by the Dynamic Torsional Vibration Method (DTVM). The apparent kinetic parameters of the cure reaction, including the gelation time tg, apparent activation energy Ea, and curing rate, etc., were estimated by Flory's gelation theory, non‐equilibrium thermodynamic fluctuation theory, and Avrami equation. The theoretical prediction is in good agreement with the experimental results obtained by the DTVM. The gelation time tg increases, and the rate of curing reaction decreases, with increasing Org‐MMT loadings, but there is no obvious effect of Org‐MMT on the apparent activation energy Ea and the curing process of nanocomposites. A two‐step cure process of UP was observed due to the addition of Org‐MMT. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1–7, 2005
Silica/polyimide hybrids and their dielectric properties. I. Preparation with an improved sol–gel process with poly(amic acid) as the precursor
Authors: Zhang Jian , Zhu Bao‐Ku , Chu Hui‐Juan , Xu You‐Yi 
Published: April 2005

AbstractA series of hybrid polyimide–silica hybrids films were prepared by a sol–gel process via the blending of tetrathoxysilane and a coupling reagent in a pyromellitic anhydride/4,4′‐oxydianiline (ODA) based poly(amic acid) solution in N,N‐dimethylacetamide, the casting of the films, the evaporation of the solvent, and thermal imidization, in that order. Fourier transform infrared, transmission electron microscopy, atomic force microscopy, and thermogravimetric analysis were used to characterize the structure of the obtained hybrids. The dispersion of silica in the hybrids was suggested to be in two states: a dominant network structure and minor discrete aggregate particles. On the basis of the network structure, the mechanical behavior of the hybrids was interpreted. An investigation of the dielectric properties revealed that the dielectric constant of the hybrids increased slowly with the concentration of SiO2. For hybrid films containing 30 wt % SiO2, the constant increased to 4.2 from the value of 3.2 for pure polyimide. Moreover, the incomplete hydrolysis and decomposition of tetrathoxysilane and the coupling reagent were the main factors contributing to the thermal stability and the uncertainty of the dielectric constant of the hybrids. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 20–24, 2005
Polyethylene/grafted polyethylene/graphite nanocomposites: Preparation, structure, and electrical properties
Authors: Shen Jing‐Wei , Huang Wen‐Yi , Zuo Sheng‐Wu , Hou Jing 
Published: April 2005

AbstractPolyethylene (PE)/maleic anhydride grafted PE (g‐PE)/expanded graphite (EG) electrically conductive nanocomposites were successfully prepared by solution intercalation (SI) and masterbatch melt mixing (MMM). Electrical conductivity (σ) measurements; transmission electron, scanning electron, and optical miscroscopy observations; and differential scanning calorimetry analyses were employed to examine the influences of the preparation methods, EG volume or weight fractions (ϕ or fw), and g‐PE weight contents (Cg) on the structure and σ of the nanocomposites, as compared to PE/g‐PE/EG composites and PE/EG control produced by direct melt mixing (DMM). The percolation thresholds (ϕc) of the SI, MMM, and DMM composites (Cg/fw = 1.5) and the DMM control were measured and found to be 2.19, 3.81, 4.68, and 5.35%, respectively. As the Cg/fw increases from 1 to 4, the σ of the MMM and DMM composites with fw = 9% rises from the order of 10−16 to 10−4 and 10−8 S/cm, respectively. These were closely associated with the morphology and microstructure of the composites varying with the preparation methods (ϕ and Cg/fw) and could also be interpreted in terms of percolation theory. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 51–59, 2005
Synthesis and characterization of novel dendritic poly(ester‐amine) with peripheral hydroxyl
Authors: Xu Dong‐Mei , Zhang Ke‐Da , Ning Chun‐Hua , Zhu Xiu‐Lin 
Published: April 2005

AbstractDendritic poly(ester‐amine) with a peripheral hydroxyl [PEA(OH)] was synthesized from dendritic PEA terminated with acrylic double bonds [PEA()] and diethanolamine (DEA) by a Michael addition reaction. The effects of the reaction temperature, time, and solvent on the purities of PEA(OH) were studied. It was found that when the mole ratio of PEA() to DEA was 1:8 and the reaction was carried out in methanol at 25°C for 22 h, the purity of PEA(OH) was 94.6%. The structure of PEA(OH) was identified by IR, 1H‐NMR, and elemental analysis. PEA(OH) is a surfactant and its aqueous form exhibits cloud points between the mass concentrations of 0.1 and 50 mass %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 60–64, 2005
Water absorption characteristics of hybrid materials incorporating tetrabutyl titanate with acrylic polymer via sol–gel process
Authors: Perrin F. X. , Nguyen V. N. , Vernet J. L. 
Published: April 2005

AbstractThe sol–gel process was used to prepare organic/inorganic hybrids utilizing a terpolymer of n‐butyl methacrylate, methyl methacrylate, and methacrylic acid as an organic phase and titanium tetrabutoxide as a precursor of the inorganic phase. Such hybrid materials may be of interest as primers for corrosion protection of metal substrates. In the absence of electrochemical influence, which is usually provided by anticorrosive pigments in current protective coatings, the barrier mechanism becomes one of the basic elements for protecting metals against atmospheric corrosion. In that context, we report the water uptake characteristics of hybrid films with titania content up to 16.3 wt %. The slow hydrolysis of butoxy, acetate, and carboxylate ligands, which becomes more and more obvious with an increase in titanium oxide cluster content, is found to produce a chemically driven force for water uptake in hybrids. The 4.6 wt % TiO2 hybrid results in the best balance of properties with a far lower diffusion coefficient and nearly the same amount of water absorbed at saturation compared to the polymer matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 92–102, 2005
Effect of mixing process on electromagnetic interference shielding effectiveness of nickel/acrylonitrile–butadiene–styrene composites
Authors: Chou Kan‐Sen , Huang Kuo‐Cheng , Shih Zong‐Huai 
Published: April 2005

AbstractThis article reports the effect of the mixing process on the electromagnetic interference (EMI) shielding effectiveness of nickel/acrylonitrile–butadiene–styrene (ABS) composites. Nickel in either powder or filament form was used as the filler material. It was mixed with ABS by two mixing processes: one was the Brabender‐mixing method, in which nickel was mixed in the polymer melt by a strong shear at high temperatures, and the other was a simple dry mixing method performed in a centrifugal ball mill. Our results showed that the dry‐mixing method could produce EMI shielding effectiveness of 36 dB at the 3 vol % nickel filaments level. In contrast, we need 20 vol % nickel powder to exhibit some shielding effectiveness for the Brabender method. After the nondestructive X‐ray examination and four‐point probe resistivity measurements, we concluded that better EMI shielding effectiveness could be achieved when the mixing method provided a state of uniformity on the macroscale, but not on the microscale. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 128–135, 2005
Educating senior executives in a novel strategic paradigm: early experiences of the Sustainable Enterprise Academy
Authors: Wheeler David , Zohar Asaf , Hart Stuart 
Published: April 2005

AbstractThis paper describes the introduction of ‘ustainability’ as a novel strategic paradigm to senior executive learning. Specifically, we describe the Sustainable Enterprise Academy, an executive education initiative founded by the Schulich School of Business at York University (Canada) with the active support of a number of academic collaborators, five corporations and several business and civil society organizations. The Academy is dedicated to business transformation through the application of a strategic sustainability paradigm, which assumes the desirability of business simultaneously creating economic, social and environmental value. The paper recounts the Academy's journey between 1999 and 2003, during which time five successful senior executive Business Leader Seminars were held – four in Canada and one in the US. Evaluation data from participants are presented and lessons learned described. The paper also explores future avenues of development for the Academy. Copyright © 2005 John Wiley & Sons, Ltd and ERP Environment.
Meta‐analysis combines Affymetrix microarray results across laboratories
Authors: Stevens John R. , Doerge R. W. 
Published: April 2005

AbstractWith microarray technology becoming more prevalent in recent years, it is now common for several laboratories to employ the same microarray technology to identify differentially expressed genes that are related to the same phenomenon in the same species. Although experimental specifics may be similar, each laboratory will typically produce a slightly different list of statistically significant genes, which calls into question the validity of each gene list (i.e. which list is best). A statistically‐based meta‐analytic approach to microarray analysis systematically combines results from the different laboratories to provide a single estimate of the degree of differential expression for each gene. This approach provides a more precise view of genes that are of significant interest, while simultaneously allowing for differences between laboratories. The widely‐used Affymetrix oligonucleotide array and its software are of particular interest because the results are naturally suited to a meta‐analysis. A simulation model based on the Affymetrix platform is developed to examine the adaptive nature of the meta‐analytic approach and to illustrate the utility of such an approach in combining microarray results across laboratories. Copyright © 2005 John Wiley & Sons, Ltd.
Reassessing design and analysis of two‐colour microarray experiments using mixed effects models
Authors: Rosa Guilherme J. M. , Steibel Juan P. , Tempelman Robert J. 
Published: April 2005

AbstractGene expression microarray studies have led to interesting experimental design and statistical analysis challenges. The comparison of expression profiles across populations is one of the most common objectives of microarray experiments. In this manuscript we review some issues regarding design and statistical analysis for two‐colour microarray platforms using mixed linear models, with special attention directed towards the different hierarchical levels of replication and the consequent effect on the use of appropriate error terms for comparing experimental groups. We examine the traditional analysis of variance (ANOVA) models proposed for microarray data and their extensions to hierarchically replicated experiments. In addition, we discuss a mixed model methodology for power and efficiency calculations of different microarray experimental designs. Copyright © 2005 John Wiley & Sons, Ltd.
Chiral ionic liquids: Synthesis and applications
Authors: Ding Jie , Armstrong Daniel W. 
Published: April 2005

AbstractOver the last ten years, interest and publications involving ionic liquids have expanded exponentially. Thus far, they have predominantly been used in organic synthesis and separations. However, their use is rapidly expanding into other areas of science and technology. Research involving chiral ionic liquids has been much more limited and only recently has come to the forefront. In this work, we review the synthesis of chiral ionic liquids and their use. Today, this is an area of research that is poised for rapid development and expansion. Chirality 17:281–292, 2005. © 2005 Wiley‐Liss, Inc.
Enantioselective semipreparative HPLC separation of PCB metabolites and their absolute structure elucidation using electronic and vibrational circular dichroism
Authors: Pham‐Tuan Hai , Larsson Christina , Hoffmann Frank , Bergman Åke , Fröba Michael , Hühnerfuss Heinrich 
Published: April 2005

AbstractPolychlorinated biphenyls (PCBs) remain one of the most important groups of environmental contaminants. The fate (transformation) as well as the toxicological implications of the different metabolism steps are subject to considerable debate. The aim of this study is to start a comprehensive investigation of atropisomeric PCB metabolites, i.e., hydroxy, methoxy, methylthionyl, and methylsulfonyl PCBs in different biota. For this purpose, enantioselective semipreparative liquid chromatography is used to obtain pure enantiomers of PCB metabolites. Electronic circular dichroism (UV‐CD) and vibrational circular dichroism (VCD) in combination with computational techniques were applied to determine their absolute structures. Approximately 18–25 mg of each enantiomer of the following metabolites were obtained using semipreparative HPLC on β‐cyclodextrin‐based columns: 4‐MeO‐CB149, 4‐MeS‐CB149, 4‐MeSO2‐CB149, 3‐MeS‐CB149, and 3‐MeSO2‐CB149. The enantiomeric purity of the separated enantiomers was in the range of 95.0–99.9%. Rotational angles and absolute configurations were also determined. This study establishes a sound method for future preparation and absolute structure determination of compounds belonging to the same class. Chirality 17:266–280, 2005. © 2005 Wiley‐Liss, Inc.
The Chemical History of a Candle ‐ Faradays Weihnachtsvorlesung im Chemieunterricht
Authors: Berg Johannes 
Published: April 2005

AbstractDie curricularen Vorgaben des Niedersächsischen Kultusministeriums für die Schuljahrgänge 5/6, die seit dem Schuljahr 2003/2004 in Kraft sind, lassen bei dem Themenbereich Feuer spontan an die Vorlesungen von Michael Faraday, die er als Professor für Chemie an der Royal Institution in London im Dezember 1860 und Januar 1861 für die Jugend hielt, denken [1, S.17, 18]. In diesem Beitrag wird eine Gegenüberstellung von Teilen der Faraday‐Vorlesungen und Teilen der curricularen Vorgaben für die Schuljahrgänge 5/6 der allgemein bildenden Schulen in Niedersachsen gegeben. Die Konzeption und die Versuche Faradays lassen sich nach meiner Überzeugung auch in den Anfangsunterricht Chemie anderer Bundesländer übertragen.
Das Sweetzym. Möglichkeiten seines Einsatzes in einem Chemieunterricht mit fächerübergreifender Perspektive
Authors: Heimann Rebekka 
Published: April 2005

AbstractIm Rahmen eines Unterrichts, der naturwissenschaftliche Fragestellungen integrativ erarbeitet, spielt die Enzymatik eine bedeutende Rolle. Chemische und biologische Aspekte können dabei vernetzt werden.
Postnatal development of alkaline phosphatase activity correlates with the maturation of neurotransmission in the cerebral cortex
Authors: Fonta Caroline , Negyessy Laszlo , Renaud Luc , Barone Pascal 
Published: April 2005

AbstractWe have shown previously that the tissue nonspecific alkaline phosphatase (TNAP) is selectively expressed in the synaptic cleft of sensory cortical areas in adult mammals and, by using sensory deprivation, that TNAP activity depends on thalamocortical activity. We further analyzed this structural functional relationship by comparing the developmental pattern of TNAP activity to the maturation of the thalamocortical afferents in the primate brain (Callithrix jacchus). Cortical expression of alkaline phosphatase (AP) activity reflects the sequential maturation of the modality‐specific sensory areas. Within the visual cortex, the regional and laminar distribution of AP correlates with the differential maturation of the magno‐ and parvocellular streams. AP activity, which is transiently expressed in the white matter, exhibits a complementary distributional pattern with myelin staining. Ultrastructural analysis revealed that AP activity is localized exclusively to the myelin‐free axonal segments, including the node of Ranvier. It was also found that AP activity is gradually expressed in parallel with the maturation of synaptic contacts in the neuropile. These data suggest the involvement of AP, in addition to neurotransmitter synthesis previously suggested in the adult, in synaptic stabilization and in myelin pattern formation and put forward a role of AP in cortical plasticity and brain disorders. J. Comp. Neurol. 486:179–196, 2005. © 2005 Wiley‐Liss, Inc.
Ionotropic glutamate receptors are expressed in GABAergic terminals in the rat superficial dorsal horn
Authors: Lu Chun‐Rong , Willcockson Helen H. , Phend Kris D. , Lucifora Simona , Darstein Melanie , Valtschanoff Juli G. , Rustioni Aldo 
Published: April 2005

AbstractIonotropic glutamate receptors (IGR), including NMDA, AMPA, and kainate receptors, are expressed in terminals with varied morphology in the superficial laminae (I–III) of the dorsal horn of the spinal cord. Some of these terminals can be identified as endings of primary afferents, whereas others establish symmetric synapses, suggesting that they may be γ‐aminobutyric acid (GABA)‐ergic. In the present study, we used confocal and electron microscopy of double immunostaining for GAD65, a marker for GABAergic terminals, and for subunits of IGRs to test directly whether IGRs are expressed in GABAergic terminals in laminae I–III of the dorsal horn. Although colocalization is hard to detect with confocal microscopy, electron microscopy reveals a substantial number of terminals immunoreactive for GAD65 also stained for IGRs. Among all GAD65‐immunoreactive terminals counted, 37% express the NMDA receptor subunit NR1; 28% are immunopositive using an antibody for the GluR2/4 subunits of the AMPA receptor; and 20–35% are immunopositive using antibodies for the kainate receptor subunits GluR5, GluR6/7, KA1, or KA2. Terminals immunoreactive for IGR subunits and GAD65 establish symmetric synapses onto dendrites and perikarya and can be presynaptic to primary afferent terminals within both type 1 and type 2 synaptic glomeruli. Activation of presynaptic IGR may reduce neurotransmitter release. As autoreceptors in terminals of Aδ and C afferent fibers in laminae I–III, presynaptic IGRs may play a role in inhibiting nociception. As heteroreceptors in GABAergic terminals in the same laminae, on the other hand, presynaptic IGRs may have an opposite role and even contribute to central sensitization and hyperalgesia. J. Comp. Neurol. 486:169–178, 2005. © 2005 Wiley‐Liss, Inc.