bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of silica reinforcement on natural rubber and butadiene rubber vulcanizates by a sol–gel reaction with tetraethoxysilane
Authors: Chung Kyong‐Hwan 
Published: March 2008

AbstractThe effect of silica reinforcement was studied for natural rubber (NR) and butadiene rubber (BR) vulcanizates by a sol–gel reaction with tetraethoxysilane at different temperatures. The formation of silica in the rubber vulcanizates was investigated analytically with Fourier transform infrared spectroscopy and energy‐dispersive X‐ray analysis. The variations of the mechanical and dynamic properties were measured in the NR and BR vulcanizates with silica filling. The hardness of the rubber vulcanizates increased with silica filling in the rubber matrix. The tensile strength and elongation at break decreased with silica filling in the NR vulcanizates. The moduli at 50, 100, and 300% elongation increased with silica filling in the rubber matrix. The storage modulus of silica‐filled rubber vulcanizates became higher than that of pure rubber vulcanizates. The temperature dependence of the loss modulus also increased with silica filling. The temperature dependence of the loss tangent was maintained, regardless of silica filling in the BR vulcanizates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Change in fiber properties due to the heat treatment of nylon 6 tire cords
Authors: Rath J. P. , Chaki T. K. , Khastgir D. 
Published: March 2008

AbstractNylon 6 is used as a reinforcing material in different rubber products. However, as it is a thermoplastic material, it may undergo some kind of thermal shrinkage during the vulcanization of rubber, which leads to dimensional stability problems in the rubber product. To prevent this, we subjected nylon 6 to some kind of thermal treatment at higher temperatures. During thermal treatment, there was some change in the mechanical properties, shrinkage which may have been correlated with changes in the crystal structure of the polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Mechanical, morphological, and thermal properties of polypropylene/kaolin composite. Part I. The effects of surface‐treated kaolin and processing enhancement
Authors: Ariffin A. , Mansor A. S. , Jikan S. S. , Mohd. Ishak Z. A. 
Published: March 2008

AbstractAll of the composites were prepared using Brabender internal mixer (50 rpm, 190°C) and molded using compression mold (190°C) to form test samples. The results showed that the tendency of kaolin particles to agglomerate was too strong, resulting in low strength and rigidity but fairly good toughness. To overcome the kaolin agglomerations dilemma, quaternary ammonium compound (QAC), sodium hexametaphosphate (SHMP), sodium hydroxide (NaOH), and polypropylene (PP) grafted maleic anhydride (PPgMAH) surface treatment agents were applied. Better dispersion of kaolin fillers were obtained with reduced size of the agglomerates. It was also found that nonreactive treatments enhanced the toughness of the composite remarkably, because of the softening effect that promotes plastic deformations. QAC was found to be the most effective dispersing agent of kaolin in PP matrix and contributes to 47% increment in the impact strength value compared to the untreated kaolin composite. QAC‐treated kaolin also shows the most remarkable increment in melt flow index (MFI) and degree of crystallization (DOC) beyond other composites. To improve the dispersion and affinity of kaolin fillers to PP matrix, the processing enhancement was conducted at the end of the experiment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Metal ion retention using the ultrafiltration technique: Preparation, characterization of the water‐soluble poly(1‐vinyl‐2‐pyrrolidone‐co‐itaconic acid) and its metal complexes in aqueous solutions
Authors: Pizarro Guadalupe del C. , Marambio Oscar G. , Jeria‐Orell Manuel , Huerta Margarita R. , Rivas Bernabé L. , Habicher Wolf D. 
Published: March 2008

AbstractRadical copolymerization of 1‐vinyl‐2‐pyrrolidone with itaconic acid at different feed monomer ratios (75–25 mol %) were investigated. The copolymers were characterized by elemental analysis, Fourier transform infrared (FTIR), 1H and 13C NMR spectroscopy. The copolymer composition was determined from elemental analysis and found to be statistical copolymers. Additionally, viscosimetric measurements, molecular weight, and polydispersity have been determined. The metal complexation of poly(1‐vinyl‐2‐pyrrolidone‐co‐itaconic acid) for the metal ions such as Cr(III), Co (II), Zn(II), Ni(II), Cu(II), Cd(II), and Fe(III) were investigated at pH 3, 5, and 7 in aqueous solution. The metal ion interaction with hydrophilic polymers was determined as a function of the pH and filtration factor. Poly(1‐vinyl‐2‐pyrrolidone‐co‐itaconic acid) showed a high affinity for the metal ions at pH 5 and 7. The poly(NVP‐co‐IA), with a copolymer composition of 29 : 71 mol % (PVA‐3), presented the highest metal ion retention values, particularly at higher pHs, at which the carboxylic acid groups are nonprotonated and could easily coordinate with the metal ions. According to the interaction pattern obtained, Cr(II), Zn(II), Pb(II), and Ni(II) formed the most stable complexes at pH 7. The thermal behaviors of the copolymer and polymer metal complex were characterized using differential scanning calorimetry (DSC) and thermogravimetry techniques under nitrogen atmosphere. The copolymers present high thermal stability and do not present glass transition in DSC curves between 25 and 500°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Preparation and characterization of silver nanoparticles with dendrimers as templates
Authors: Jin Lei , Yang Shi‐Ping , Wu Hui‐Xia , Huang Wei‐Wei , Tian Qi‐Wei 
Published: March 2008

AbstractIn this study, crystal silver nanoparticle clusters, prepared by the reduction of AgNO3 in the presence of third‐to‐sixth‐generation dendrimers with a trimesyl core, were characterized with ultraviolet–visible spectroscopy, transmission electron microscopy, and energy‐dispersive X‐ray spectroscopy. The results showed that the particle size of the silver nanoparticles was considerably affected by the generation of the dendrimers as well as the dendrimer concentration. When the concentration ratios of Ag+ to the third‐to‐sixth‐generation dendrimers were all 4 : 1, the average diameters of the obtained particles were 6.7, 6.0, 5.2, and 4.3 nm, respectively. The data from high‐resolution transmission electron microscopy and electron diffraction indicated that the particles belonged to a simple cubic crystal structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Prophenoloxidases 1 and 2 from the spruce budworm, Choristoneura fumiferana: Molecular cloning and assessment of transcriptional regulation by a polydnavirus
Authors: Doucet Daniel , Béliveau Catherine , Dowling Ashley , Simard Jocelyne , Feng Qili , Krell Peter J. , Cusson Michel 
Published: March 2008

AbstractImmune challenge in arthropods is frequently accompanied by melanization of the hemolymph, a reaction triggered by the activation of prophenoloxidase (PPO). Because their immature stages are spent inside the hemocoel of insect larvae, endoparasitoids have evolved strategies to escape or counter melanin formation. Very little molecular information is available on these endoparasitoid counterstrategies. We have sought to shed light on the inhibition of melanization in the spruce budworm, Choristoneura fumiferana, by the parasitic wasp Tranosema rostrale, by cloning two host PPO homologs and studying their transcriptional regulation after parasitization. The two polypeptides are encoded by transcripts of ˜3.3 kb (for CfPPO1) and 3.0 kb (for CfPPO2) and possess structural features typical of other insect PPOs. While there appears to be a single CfPPO2 gene in the C. fumiferana genome, we detected three CfPPO1 mRNA variants displaying insertions/deletions in the 3′ untranslated region, suggesting that there may be more than one CfPPO1 gene copy. Both CfPPO1 and CfPPO2 were expressed at high levels in C. fumiferana 6th instars, and parasitization by T. rostrale had no apparent impact on the level of their transcripts. Injection of a large dose (0.5 female‐equivalent) of polydnavirus‐laden calyx fluid extracted from T. rostrale, which is known to inhibit melanization in C. fumiferana, only caused a transient decrease in CfPPO1 and CfPPO2 transcript accumulation at 2–3 d post injection. It thus appears that transcriptional downregulation of C. fumiferana PPO by T. rostrale plays a minor role in the inhibition of hemolymph melanization in this host‐parasitoid system. Arch. Insect Biochem. Physiol. 67:188–201, 2008. Published 2008 Wiley‐Liss, Inc.†
Comparison of three methods of parasitoid polydnavirus genomic DNA isolation to facilitate polydnavirus genomic sequencing
Authors: Rodríguez‐Pérez Mario A. , Beckage Nancy E. 
Published: March 2008

AbstractA major long‐term goal of polydnavirus (PDV) genome research is to identify novel virally encoded molecules that may serve as biopesticides to target insect pests that threaten agriculture and human health. As PDV viral replication in cell culture in vitro has not yet been achieved, several thousands of wasps must be dissected to yield enough viral DNA from the adult ovaries to carry out PDV genomic sequencing. This study compares three methods of PDV genomic DNA isolation for the PDV of Cotesia flavipes, which parasitizes the sugarcane borer, Diatraea saccharalis, preparatory to sequencing the C. flavipes bracovirus genome. Two of these protocols incorporate phenol‐chloroform DNA extraction steps in the procedure and the third protocol uses a modified Qiagen DNA kit method to extract viral DNA. The latter method proved significantly less time‐consuming and more cost‐effective. Efforts are currently underway to bioengineer insect pathogenic viruses with PDV genes, so that their gene products will enhance baculovirus virulence for agricultural insect pests, either via suppression of the immune system of the host or by PDV‐mediated induction of its developmental arrest. Sequencing a growing number of complete PDV genomes will enhance those efforts, which will be facilitated by the study reported here. Arch. Insect Biochem. Physiol. 67:202–209, 2008. © 2008 Wiley‐Liss, Inc.
Persea americana (avocado): bringing ancient flowers to fruit in the genomics era
Authors: Chanderbali André S. , Albert Victor A. , Ashworth Vanessa E.T.M. , Clegg Michael T. , Litz Richard E. , Soltis Douglas E. , Soltis Pamela S. 
Published: March 2008

AbstractThe avocado (Persea americana) is a major crop commodity worldwide. Moreover, avocado, a paleopolyploid, is an evolutionary “outpost” among flowering plants, representing a basal lineage (the magnoliid clade) near the origin of the flowering plants themselves. Following centuries of selective breeding, avocado germplasm has been characterized at the level of microsatellite and RFLP markers. Nonetheless, little is known beyond these general diversity estimates, and much work remains to be done to develop avocado as a major subtropical‐zone crop. Among the goals of avocado improvement are to develop varieties with fruit that will “store” better on the tree, show uniform ripening and have better post‐harvest storage. Avocado transcriptome sequencing, genome mapping and partial genomic sequencing will represent a major step toward the goal of sequencing the entire avocado genome, which is expected to aid in improving avocado varieties and production, as well as understanding the evolution of flowers from non‐flowering seed plants (gymnosperms). Additionally, continued evolutionary and other comparative studies of flower and fruit development in different avocado strains can be accomplished at the gene expression level, including in comparison with avocado relatives, and these should provide important insights into the genetic regulation of fruit development in basal angiosperms. BioEssays 30:386–396, 2008. © 2008 Wiley Periodicals, Inc.
Gene duplications, robustness and evolutionary innovations
Authors: Wagner Andreas 
Published: March 2008

AbstractMutational robustness facilitates evolutionary innovations. Gene duplications are unique kinds of mutations, in that they generally increase such robustness. The frequent association of gene duplications in regulatory networks with evolutionary innovation is thus a special case of a general mechanism linking innovation to robustness. The potential power of this mechanism to promote evolutionary innovations on large time scales is illustrated here with several examples. These include the role of gene duplications in the vertebrate radiation, flowering plant evolution and heart development, which encompass some of the most striking innovations in the evolution of life. BioEssays 30:367–373, 2008. © 2008 Wiley Periodicals, Inc.
Silicon nanotechnologies of pigmented heterokonts
Authors: Grachev Mikhail A. , Annenkov Vadim V. , Likhoshway Yelena V. 
Published: March 2008

AbstractMany pigmented heterokonts are able to synthesize elements of their cell walls (the frustules) of dense biogenic silica. These include diatom algae, which occupy a significant place in the biosphere. The siliceous frustules of diatoms have species‐specific patterns of surface structures between 10 and a few hundred nanometers. The present review considers possible mechanisms of uptake of silicic acid from the aquatic environment, its transport across the plasmalemma, and intracellular transport and deposition of silica inside the specialized Silica Deposition Vesicle (SDV) where elements of the new frustule are formed. It is proposed that a complex of silicic acid with positively charged proteins silaffins and polypropylamines remains a homogeneous solution during the intracellular transport to SDV, where biogenic silica precipitates. The high density of the deposited biogenic silica may be due to removal of water from the SDV by aquaporins followed by syneresis—a process during which pore water is expelled from the network of the contracting gel. The pattern of aquaporins in the silicalemma, the membrane embracing the SDV, can determine the pattern of species‐specific siliceous nanostructures. BioEssays 30:328–337, 2008. © 2008 Wiley Periodicals, Inc.
Wrestling off RAD51: a novel role for RecQ helicases
Authors: Wu Leonard 
Published: March 2008

AbstractHomologous recombination (HR) is essential for the accurate repair of DNA double‐strand breaks and damaged replication forks. However, inappropriate or aberrant HR can also result in genome rearrangements. The maintenance of cell viability is, therefore, a careful balancing act between the benefits of HR (the error‐free repair of DNA strand breaks) and the potential detrimental outcomes of HR (chromosomal rearrangements). Two papers have recently provided a mechanistic insight into how HR may be tempered by RecQ helicases to prevent genome instability and diseases that are a consequence of this, such as cancer.1,2 BioEssays 30:291–295, 2008. © 2008 Wiley Periodicals, Inc.
Multicellular behavior in bacteria: communication, cooperation, competition and cheating
Authors: Dunny Gary M. , Brickman Timothy J. , Dworkin Martin 
Published: March 2008

AbstractThe sociobiology of bacteria, largely unappreciated and ignored by the microbiology research community two decades ago is now a major research area, catalyzed to a significant degree by studies of communication and cooperative behavior among the myxobacteria and in quorum sensing (QS) and biofilm formation by pseudomonads and other microbes. Recently, the topic of multicellular cooperative behaviors among bacteria has been increasingly considered in the context of evolutionary biology. Here we discuss the significance of two recent studies1,2 of the phenomenon of “cheating” mutants and their exploitation of cooperating microbial populations of Pseudomonas aeruginosa. BioEssays 30:296–298, 2008. © 2008 Wiley Periodicals, Inc.
Child abuse in South Africa: rights and wrongs
Authors: Richter Linda M. , Dawes Andrew R. L. 
Published: March 2008

AbstractIn a country in which human rights feature prominently in our discourse about who we are, as well as in the South African constitutional and legal framework, so many wrongs continue to be done to children. One category of wrongs is abuse, but it is not the only one. Poverty, patriarchy and gender violence, as well as the socialised obedience, dependency and silence of women and children, create conditions in which abuse can occur, often with few consequences. South Africa has extremely high rates of both physical and sexual abuse of children. Progressive, rights‐based legislation exists to protect children, but it is not adequately supported or resourced by services to fulfil their provisions. Child abuse and neglect will not be significantly reduced in South Africa, without simultaneous improvements in the social and economic conditions in which very large numbers of children live. Copyright © 2008 John Wiley & Sons, Ltd.
Changes in calcium‐dependent membrane permeability properties in mitochondria of livers from arthritic rats
Authors: Silva Pamelli Maria de Souza , Tanabe Eduardo , Hermoso Aparecida Pinto Munhos , Bersani‐Amado Ciomar A. , Bracht Adelar , Ishii‐Iwamoto Emy L. , Salgueiro‐Pagadigorria Clairce Luzia 
Published: March 2008

AbstractThe involvement of the mitochondrial permeability transition pore (PTP) in the responses of mitochondria from adjuvant‐induced arthritic rats to Ca2+ addition was investigated. The respiratory activity, the Ca2+‐induced osmotic swelling and the electrophoretic 45Ca2+ uptake were evaluated in the absence and in the presence of cyclosporin A (CsA), a well‐known inhibitor of the mitochondrial PTP. The Ca2+‐induced mitochondrial permeability transition (MPT) process occurred in mitochondria from arthritic rats even in the presence of a low Ca2+ concentration. Whereas in the normal condition, the Ca2+‐induced uncoupling of oxidative phosphorylation and osmotic swelling was observed in the presence of 10 or 20 µM Ca2+ concentration, in the arthritic condition, these events occurred at 1.0 µM concentration. In addition, mitochondria from arthritic rats presented an impaired ability to accumulate 45Ca2+. All these effects were completely prevented by the administration of CsA. The results of the present study suggest that the higher sensitivity of mitochondria from arthritic rats to Ca2+‐induced MPT may be an important factor in the pathogenesis of the arthritis disease. Copyright © 2008 John Wiley & Sons, Ltd.
BimEL‐dependent apoptosis induced in peripheral blood lymphocytes with n‐butyric acid is moderated by variation in expression of c‐myc and p21(WAF1)
Authors: Kalousek Ivan , Brodska Barbora , Otevrelova Petra , Röselova Pavla 
Published: March 2008

AbstractWe have examined the effect of sodium butyrate (SB) on the viability of normal peripheral blood lymphocytes (PBLs) in vitro and the effect of this agent on the expression of 20 apoptosis‐related genes. Data suggest that PBL treated with 2 mmol L−1 SB resisted for at least 8 h the destructive activity of the agent, but eventually 30% of cells died within 72 h. As documented by flow cytometry and cytochrome c release study, cells underwent mitochondrial‐derived apoptosis. While the expression of the majority of genes examined by RT‐PCR and Western blots remained indifferent to 2 mmol L−1 SB, the cellular levels of BimEL, c‐myc, p53, and p21(WAF1) varied profoundly with the time of SB treatment. The Bax activator BimEL increased rapidly, driving cells toward apoptosis likely controlled by c‐myc and p21(WAF1) activities. The c‐myc, exercising the role of mediator of the function of BimEL and inhibitor of p21(WAF1) expression, decreased significantly for several hours after adding SB but within 48 h it returned to close to its original value. An apoptosis inhibitor and executive caspase substrate p21(WAF1) increased early at the beginning of treatment but subsequently, within a time frame of 72 h, profoundly dropped in terms of both a caspase‐dependent and caspase‐independent way. We suggest that variations in c‐myc and p21(WAF1) expression delay apoptosis making PBL resistant to SB for several hours, and together with fast catabolism of SB in vivo protect PBL against the destructive activity of this anti‐cancerous metabolite of colonic bacteria. Copyright © 2008 John Wiley & Sons, Ltd.
A Molecular Dynamics Study of the ASC and NALP1 Pyrin Domains at Neutral and Low pH
Authors: Gattin Zrinka , van Gunsteren Wilfred F. 
Published: March 2008

AbstractThe pyrin domain is one of four subfamilies of the death domain superfamily of proteins, all members of which share a similar three‐dimensional fold with a structure comprising five or six antiparallel α‐helices. The pyrin domain of the ASC (six‐helical fold) and of the NALP1 (five‐helical fold) proteins were simulated at two different pH values, 3.7 and 6.5, with two different force‐field parameter sets, and the molecular dynamics simulation trajectories were compared to NMR experimental data. The two force fields that were used did not show very different results. The simulations of NALP1 at pH 6.5 largely satisfied the experimental NOE atom–atom distance bounds that were measured at pH 6.5, and preserved its tertiary structure. The simulations at pH 3.7 showed a denaturation of the protein. The simulations of ASC at pH 3.7 only satisfied the experimental NOE atom–atom distance bounds that were measured at pH 3.7 if either three acidic side chains (Asp48, Glu64 and Asp75) or only two (Glu64 and Asp75) were not protonated. This indicates that the ASC tertiary structure is stabilized by salt bridges at low pH. A corresponding analysis for NALP1 at pH 3.7 only yielded one possible salt bridge, but this did not stabilize the tertiary structure at low pH. The results show that the particular protonation states of acidic side chains in the protein interior might be crucial to properly modeling these proteins at low pH.
An ESI‐MS/MS Method for Screening of Small‐Molecule Mixtures against Glycogen Synthase Kinase‐3β (GSK‐3β)
Authors: Partserniak Ivan , Werstuck Geoff , Capretta Alfredo , Brennan John D. 
Published: March 2008

AbstractGlycogen synthase kinase‐3β (GSK‐3β) is involved in the hyperphosphorylation of previously phosphorylated (primed) substrates, and is currently assayed using an approach based on the incorporation of γ‐32P‐radiolabelled isotopes into substrate peptides. The requirement to detect hyperphosphorylation of a primed substrate poses a particular challenge for development of a high‐throughput screening assay, as many current kinase assays are designed to produce a signal in the presence of any phosphorylation site, and thus are only suitable for β‐unphosphorylated substrates. Herein, we have developed an electrospray‐ionization tandem mass spectrometry (ESI‐MS/MS) assay to allow for direct detection of a hyperphosphorylated product which is formed in a solution reaction involving a primed peptide substrate (GSM peptide) and GSK‐3β. Optimum reaction conditions (level of Mg2+, buffer type, ionic strength, pH, enzyme concentration, and reaction time) were established to both maintain the activity of GSK‐3β and allow for substrate and product quantification through ESI/MS/MS. We show that the MS‐based assay allows for rapid determination of GSK‐3β activity from reaction volumes of ∼40 μL and that it can be used to assess IC50 values and the site of action of known inhibitors. It also can be used for automated screening of small‐molecules mixtures to identify inhibitors of GSK‐3β.