bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uncertainty analysis of complex structural systems
Authors: Schuëller G. I. , Pradlwarter H. J. 
Published: February 2009

AbstractIn this paper methods for uncertainty propagation for complex structural systems are discussed. Only a limited class of methods is available for this purpose. It is shown that only numerical procedures allow the uncertainty assessment and reliability estimation of such systems. In particular, the perturbation procedure, the Karhunen–Loève reduction scheme, the polynomial chaos expansion, direct and advanced Monte Carlo simulation (MCS), as well as random matrix theory meet these requirements. It is shown that advanced MCS procedures proved to be the most versatile approach. Copyright © 2009 John Wiley & Sons, Ltd.
A partitioned model for fluid–structure interaction problems using hexahedral finite elements with one‐point quadrature
Authors: Braun Alexandre Luis , Awruch Armando Miguel 
Published: February 2009

AbstractA partitioned numerical model for fluid–structure interaction analysis of incompressible flows and structures with geometrically non‐linear behavior is presented in this work. The flow analysis is performed considering the well‐known Navier–Stokes equations for Newtonian fluids and the continuity equation, obtained from the pseudo‐compressibility hypothesis. An explicit two‐step Taylor‐Galerkin scheme is employed in the time discretization procedure of the system of governing equations, which is expressed in terms of an arbitrary Lagrangean‐Eulerian description. The structural subsystem is analyzed using a geometrically non‐linear elastic model and the respective equation of motion is discretized in the time domain employing the Generalized‐α scheme. Fluid–structure coupling is taken into account regarding a new energy‐conserving partitioned scheme with non‐linear effects, which is accomplished by enforcing equilibrium and kinematical compatibility conditions at the solid–fluid interface. Non‐matching meshes and subcycling are also considered in the present model. The finite element method is employed for spatial discretizations using eight‐node hexahedral elements with one‐point integration in both fields. Some numerical examples are simulated in order to demonstrate the applicability of the proposed formulation. Copyright © 2009 John Wiley & Sons, Ltd.
Preparation and applications of novel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite nanocomposites
Authors: Takashima Hiroki , Iwaki Ken‐ichi , Takishita Katsuhisa , Sawada Hideo 
Published: February 2009

AbstractNovel fluoroalkyl end‐capped vinyltrimethoxysilane oligomer/hydroxyapatite (HAp) nanocomposites were prepared by the reaction of calcium nitrate tetrahydrate and phosphoric acid in the presence of the corresponding oligomer. These fluorinated oligomer/HAp composites thus obtained are nanometer size‐controlled fine particles (83–173 nm), and were found to exhibit good dispersibility in methanol, ethanol, and isopropyl alcohol. These fluorinated HAp nanocomposites were applied to the surface modification of glass and poly(methyl methacrylate) (PMMA) to exhibit good hydro‐ and oleophobic characteristics imparted by fluorine on their surface. In addition, the surface structural changes of the modified polyethylene terephtalate and PMMA films treated with these fluorinated nanocomposites before and after soaking in a simulated body fluid (SBF) were analyzed by using SEM, XRD, and EDX to observe the formation of spherical HAp deposits on the surface. Copyright © 2009 John Wiley & Sons, Ltd.
Switching the conformational behaviour of poly(N‐isopropyl acrylamide)
Authors: Rimmer Stephen , Soutar Ian , Swanson Linda 
Published: February 2009

AbstractIn this review we present data highlighting the power and versatility of luminescence spectroscopy in the study of the conformational behaviour of poly(N‐isopropyl acrylamide) (PNIPAM). PNIPAM shows a lower critical solution temperature (LCST) in aqueous solution at 32 °C. Fluorescence time‐resolved anisotropy measurements (TRAMS) have confirmed that a conformational change occurs from an expanded open chain to a globular structure at the LCST, which forms the basis of phase separation observed for semi‐dilute concentrations. The coiled conformation can solubilise low‐molar‐mass species as revealed by the spectral profile of pyrene and is extremely protective: intersystem crossing to the triplet manifold can be enhanced by use of a heavy‐atom promoter (bromostyrene) copolymerised with NIPAM and trace levels of acenaphthylene allowing generation of phosphorescence at temperatures as high as 50 °C in aqueous solution. Manipulation of the conformational switch of PNIPAM is possible via simple free radical copolymerisation. However, a reduction in the magnitude of the transition occurs, which has an impact on the solubilisation properties of the resultant copolymers. Alternative strategies are suggested to overcome this problem: synthesis of graft copolymers allows fine‐tuning of the thermal response whilst maintaining the magnitude of the transition as revealed by TRAMS. Copyright © 2009 Society of Chemical Industry
Thermal behaviour of poly(lactic acid) in contact with compressed carbon dioxide
Authors: Yu Long , Liu Hongsheng , Dean Katherine 
Published: February 2009

AbstractBACKGROUND: The thermal behaviour of poly(lactic acid) (PLA) in contact with compressed CO2 was studied using high‐pressure differential scanning calorimetry. In particular, the effect of annealing below and above the glass transition temperature (Tg) on the glass transition, cold crystallization and melting temperatures was studied systematically as a function of annealing time and pressure.RESULTS: The effect of compressed CO2 on the thermal properties of PLA is time dependent. Annealing below Tg decreases the temperature and enthalpy of cold crystallization. Similar, but more evident, behaviours are observed when annealing above Tg. Crystallization temperature and enthalpy during cooling decrease with increasing pressure, and the peak is narrower.CONCLUSION: Annealing PLA in the presence of compressed CO2 accelerates cold crystallization, but retards crystallization during cooling. Copyright © 2009 Society of Chemical Industry
Anionic triphenylamine‐ and fluorene‐based conjugated polyelectrolyte as a hole‐transporting material for polymer light‐emitting diodes
Authors: Shi Wei , Wang Lei , Huang Fei , Liu Ransheng , Yang Wei , Cao Yong 
Published: February 2009

AbstractBACKGROUND: Hole‐transport layers (HTLs) play a crucial role in multilayer polymeric light‐emitting diodes (PLEDs) for the achievement of satisfactory device performance. During the fabrication of multilayer PLEDs via solution processing, the fabricated HTLs encounter the risk of erosion during the film‐forming process of subsequent emitting layers (EMLs). In contrast to the widely investigated crosslinkable HTLs, much less attention has been paid to the preparation of polar‐solvent‐soluble HTLs, which is a straightforward solution to overcome the interfacial mixing between HTLs and EMLs during solution processing.RESULTS: Alternating triphenylamine‐ and fluorene‐based anionic copolymer poly[9,9‐bis(4′‐sulfonatobutyl)fluorene‐alt‐N‐(p‐trifluoromethyl)phenyl‐4,4′‐diphenylamine]sodium salt (PFT‐CF3) was synthesized via a palladium‐catalyzed Suzuki coupling reaction. This polyelectrolyte is soluble only in polar solvents such as methanol, dimethylformamide and dimethylsulfoxide rather than in non‐polar solvents such as toluene, chloroform and xylene. The relatively high HOMO (−5.22 eV) and LUMO (−2.26 eV) levels of this polymer endow it simultaneously with good hole‐transporting and electron‐blocking capabilities. The performance of red‐, green‐ and blue‐emitting devices utilizing this polyelectrolyte as HTL was investigated.CONCLUSION: The anionic conjugated polyelectrolyte based on triphenylamine and fluorene, PFT‐CF3, can serve as a promising hole‐transporting/electron‐blocking layer in multilayer PLEDs. Copyright © 2009 Society of Chemical Industry
Hydroxyalkoxy derivatives of oxamic acid: polyol substrates for polyurethane foams
Authors: Zarzyka‐Niemiec Iwona 
Published: February 2009

AbstractBACKGROUND: The work reported aimed at obtaining hydroxyalkoxy derivatives containing oxalamidoester groups starting from oxamic acid (OA) substrate. These derivatives were then used for the synthesis of polyurethane foams.RESULTS: The hydroxyalkoxy derivatives were obtained by reaction of OA with 6 to 15 molar excess of ethylene carbonate (1,3‐dioxolane‐2‐one) or propylene carbonate (4‐methyl‐1,3‐dioxolane‐2‐one). The products obtained have good thermal stability and possess suitable physical properties for use as substrates for foamed polyurethanes.CONCLUSION: The rigid polyurethane foams obtained from the hydroxyalkoxy derivatives of OA possess enhanced thermal stability and good mechanical properties in comparison with traditional polyurethane foams. Copyright © 2009 Society of Chemical Industry
Cytoskeleton‐associated proteins are enriched in human embryonic‐stem cell‐derived neuroectodermal spheres
Authors: Chae Jung‐Il , Kim Janghwan , Woo Sun‐Mi , Han Hyo‐Won , Cho Young Keun , Oh Keon‐Bong , Nam Ki‐Hoan , Kang Yong‐Kook 
Published: February 2009

AbstractThe ability to generate neural lineages from human embryonic stem cells (hESCs) in a controlled manner would further investigation of human neurogenesis and development of potential cell therapeutic applications to treat neurological diseases; however, generating such neural stem cells (NSCs) remains a challenge. In an attempt to characterize the cellular mechanisms involved in hESC differentiation into neuroprogenitor cells, we performed 2‐DE using protein extracts from hESC‐derived embryoid bodies (EBs) and neuroectodermal spheres (NESs) bearing neuroprogenitors. Of 47 differentially expressed protein spots, 28 nonredundant spots were shown to be upregulated in the NESs; these protein spots included neurogenesis‐related proteins (TAF1, SEPT2, NPH3, and CRABP), as expected. Interestingly, 6 of these 28 protein spots were cytoskeleton‐associated proteins (CSAP) such as Fascin‐1, Cofilin‐1, and Stathmin‐1. Western‐blot analyses confirmed the increased levels of these proteins in the NESs. Furthermore, immunostaining analysis showed that both Fascin‐1 and Stathmin‐1 were preferentially expressed in the inner rims of neural rosettes, which are characteristic features of neuroprogenitors in culture. We also confirmed prominent expression of Fascin‐1 in (sub‐)ventricular zone in E15.5 mouse fetal brain. Our results suggest that, in addition to the induction of those genes involved in neural development, hESC differentiation into the NES is associated with a marked reorganization of the cellular cytoskeleton.
Proteome of synaptosome‐associated proteins in spinal cord dorsal horn after peripheral nerve injury
Authors: Singh Om V. , Yaster Myron , Xu Ji‐Tian , Guan Yun , Guan Xiaowei , Dharmarajan Arun M. , Raja Srinivasa N. , Zeitlin Pamela L. , Tao Yuan‐Xiang 
Published: February 2009

AbstractPeripheral nerve injury may lead to neuroadaptive changes of cellular signals in spinal cord that are thought to contribute to central mechanisms underlying neuropathic pain. Here we used a 2‐DE‐based proteomic technique to determine the global expression changes of synaptosome‐associated proteins in spinal cord dorsal horn after unilateral fifth spinal nerve injury (SNI). The fifth lumbar dorsal horns ipsilateral to SNI or sham surgery were harvested on day 14 post‐surgery, and the total soluble and synaptosomal fractions were isolated. The proteins derived from the synaptosomal fraction were resolved by 2‐DE. We identified 27 proteins that displayed different expression levels after SNI, including proteins involved in transmission and modulation of noxious information, cellular metabolism, membrane receptor trafficking, oxidative stress, apoptosis, and degeneration. Six of the 27 proteins were chosen randomly and further validated in the synaptosomal fraction by Western blot analysis. Unexpectedly, Western blot analysis showed that only one protein in the total soluble fraction exhibited a significant expression change after SNI. The data indicate that peripheral nerve injury changes not only protein expression but also protein subcellular distribution in dorsal horn cells. These changes might participate in the central mechanism that underlies the maintenance of neuropathic pain.
Hydrolytic stability and high Tg of polyimides derived from the novel 4,9‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]‐diamantane dianhydride
Authors: Chern Yaw‐Terng , Wang Jane‐Jen 
Published: February 2009

AbstractThis work reports the synthesis and characterization of diamantane‐based polyimides obtained from 4,9‐bis[4(3,4‐dicarboxyphenoxy)phenyl]diamantane dianhydride and various aromatic diamines. Interestingly, the diamantane‐based polyimides were very stable to hydrolysis. This novel polyimide exhibits a low dielectric constant (2.65–2.77), low moisture absorption (<0.67%), good solubility, high Tg and unusually high thermal stability. Dynamic mechanical analysis (DMA) reveals that the diamantane‐based polyimides have high Tg ranging from 281 to 379 °C. The high‐temperature β1 subglass transition around 285 °C was observed in polyimide 6a derived from 2,2′‐bis(trifluoromethyl)benzidine. This class of novel diamantane‐based polyimide is very promising for electronic applications, because of its good mechanical properties, good thermal stability, low dielectric constant, excellent hydrolytic resistance, and low moisture absorption. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1673–1684, 2009
Effect of gamma radiation on fluoropolymers
Authors: Contreras‐Garcia A. , Bucio E. , León‐c F. , Booth C. J. , Cassidy P. E. 
Published: February 2009

AbstractA series of fluoropolymer films were synthesized by reacting several bisphenol monomers with 1,3‐bis(1,1,1,3,3,3‐hexafluoro‐2‐pentafluorophenyl methoxy‐2‐propyl)benzene via a nucleophilic aromatic substitution to form polyethers. The bisphenols used included two diphenol‐substituted spirodilactams (SDL; aliphatic and aromatic), biphenol, bisphenol A, bisphenol AF, bisphenol O, and bisphenol F to form seven different polymers. Polymers were irradiated by a Gamma beam 651‐PT at a dose rate of 10.5 kGy/h; the absorbed dose in each film was varied between 300 and 1000 kGy. The effect on the chemical structure upon radiation was studied by DSC, TGA, FTIR‐ATR, and NMR after and before irradiation. Thermal analysis showed a lessened thermal stability and a lower Tg after irradiation. Further, irradiation caused a decrease in molecular weight as a result of cleavage of sp3 bonds. These data allowed calculation of the radiochemical yield scission (Gs) for each of these polymers. The SDL aromatic system proved the most radiation‐resistant. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1617–1626, 2009
Synthesis of hollow crosslinked miktoarm polymer using miniemulsion as templates
Authors: Xiong De'an , Li Zhe , Ma Rujiang , An Yingli , Shi Linqi 
Published: February 2009

AbstractHollow crosslinked polymers (HCPs) were synthesized using arm first method via atom transfer radical polymerization. The polymerization process was performed in miniemulsion system, in which the macroinitiator, PEG‐Br, was in the water phase, whereas the vinyl‐monomer, 4‐vinylpyridine (4VP), and the crosslinker, DVB, were in the butanone phase. TEM images and light scattering characterization showed that the resultant polymer contained a hollow space, and the volume of the hollow space could be adjusted by changing the ratio of water to butanone. Also, hollow crosslinked Miktoarm polymers (HCMPs) were synthesized through this method when two different macroinitiators, PEG‐Br and PNIPAM‐Br, were used to coinitiate the polymerization of the vinyl‐monomer, 4VP and DVB. The 1H NMR spectra showed that the hollow polymers contained both PEG arms and PNIPAM arms. The hollow morphologies of the resultant Miktoarm polymers were the same as the HCPs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1651–1660, 2009
Micelles possessing mixed cores and thermoresponsive shells fabricated from well‐defined amphiphilic ABC miktoarm star terpolymers
Authors: Zhang Yanfeng , Liu Hao , Dong Hefei , Li Changhua , Liu Shiyong 
Published: February 2009

AbstractAmphiphilic ABC miktoarm star terpolymers consisting of polystyrene, poly(ε‐caprolactone), and poly(N‐isopropylacrylamide) arms, PS(‐b‐PNIPAM)‐b‐PCL, were synthesized via a combination of atom transfer radical polymerization, ring‐opening polymerization (ROP), and click chemistry. Difunctional PS bearing an alkynyl and a primary hydroxyl moiety at the chain end, PS‐alknyl‐OH, was prepared by reacting azido‐terminated PS with an excess of 3,5‐bis(propargyloxy)benzyl alcohol (BPBA) under click conditions. The subsequent ROP of ε‐caprolactone using PS‐alknyl‐OH macroinitiator afforded PS(‐alkynyl)‐b‐PCL copolymer bearing an alkynyl moiety at the diblock junction point. Target PS(‐b‐PNIPAM)‐b‐PCL amphiphilic ABC miktoarm star terpolymers were then prepared via click reaction between PS(‐alkynyl)‐b‐PCL and an excess of azido‐terminated PNIPAM (PNIPAM‐N3). The removal of excess PNIPAM‐N3 was accomplished by “clicking” onto alkynyl‐functionalized Wang resin. All the intermediate and final products were characterized by gel permeation chromatography, 1H NMR, and FTIR. In aqueous solution, the obtained amphiphilic ABC miktoarm star terpolymer self‐assembles into micelles possessing mixed PS/PCL cores and thermoresponsive shells, which were further characterized by dynamic laser light scattering and transmission electron microscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1636–1650, 2009
Core‐shell particles with glycopolymer shell and polynucleoside core via RAFT: From micelles to rods
Authors: Pearson Samuel , Allen Nathan , Stenzel Martina H. 
Published: February 2009

AbstractAmphiphilic block copolymers were synthesized via the reversible addition fragmentation chain transfer (RAFT) copolymerisation of 2‐methacrylamido glucopyranose (MAG) and 5′‐O‐methacryloyl uridine (MAU). Homopolymerisations of both monomers using (4‐cyanopentanoic acid)‐4‐dithiobenzoate (CPADB) proceeded with pseudo first order kinetics in a living fashion, displaying linear evolution of molecular weight with conversion and low PDIs. A bimodal molecular weight distribution was observed for PMAU at low conversions courtesy of hybrid behavior between living and conventional free radical polymerization. This effect was more pronounced when a PMAG macroRAFT agent was chain extended with MAU, however, in both cases, good control was attained once the main RAFT equilibrium was established. A stability study on PMAU found that its hydrolysis is diffusion controlled, and is accelerated at physiological pH compared with neutral conditions. Self‐assembly of four block copolymers with increasing hydrophobic (PMAU) block lengths produced micelles, which demonstrated an increased tendency to form rods as the PMAU block length increased. Interestingly, none of the block copolymers were surface‐active. An initial assessment of PMAU's ability to bind the nucleoside adenosine through base pairing was highly promising, with DSC measurements indicating that adenosine is fully miscible in the PMAU matrix. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1706–1723, 2009
Gynecological cancer survivors and community support services: referral, awareness, utilization and satisfaction
Authors: Beesley Vanessa L , Janda Monika , Eakin Elizabeth G , Auster Josephine F , Chambers Suzanne K , Aitken Joanne F , Dunn Jeff , Battistutta Diana 
Published: February 2009

AbstractObjectives: To quantify gynecological cancer survivors' referral to, awareness of, utilization of and satisfaction with community support services, as well as the factors associated with service use.Methods: In 2004, 802 gynecological cancer survivors, 3 months–5 years post‐diagnosis, completed a postal questionnaire (56% response rate). Descriptive statistics summarized outcome prevalences. Logistic regression models identified correlates of service utilization.Results: Substantial proportions of women were aware of the main cancer support organization, Cancer Council Queensland (72%), and of information booklets (74%), helplines (66%), support groups (56%) and internet information (50%). Less than half were aware of other services. The most commonly used resources and services were information booklets (37%), the internet (23%), and helplines (20%). More broadly, 43% utilized information/internet support, 30% utilized psychosocial services and 27% utilized functional/practical services. Approximately one‐fifth (19%) used more than one support types. Having a health‐care provider referral, being diagnosed with lymphedema or living in northern Queensland were associated with higher odds of service use in all three of the support types. While most (86%) of those referred used a service, only a few women received referrals. Among users, satisfaction with services was high.Conclusions: While gynecological cancer survivors accessed a variety of support, there is a need to ensure women are aware of services. Given the low prevalence of referrals and that referral was a key influence on service use, clinician education may be necessary to improve service referral. Organizations should also consider strategies to keep services high on clinicians' radars. Copyright © 2009 John Wiley & Sons, Ltd
Structural insight into the catalytic mechanism of gluconate 5‐dehydrogenase from Streptococcus suis: Crystal structures of the substrate‐free and quaternary complex enzymes
Authors: Zhang Qiangmin , Peng Hao , Gao Feng , Liu Yiwei , Cheng Hao , Thompson John , Gao George F. 
Published: February 2009

AbstractGluconate 5‐dehydrogenase (Ga5DH) is an NADP(H)‐dependent enzyme that catalyzes a reversible oxidoreduction reaction between D‐gluconate and 5‐keto‐D‐gluconate, thereby regulating the flux of this important carbon and energy source in bacteria. Despite the considerable amount of physiological and biochemical knowledge of Ga5DH, there is little physical or structural information available for this enzyme. To this end, we herein report the crystal structures of Ga5DH from pathogenic Streptococcus suis serotype 2 in both substrate‐free and liganded (NADP+/D‐gluconate/metal ion) quaternary complex forms at 2.0 Å resolution. Structural analysis reveals that Ga5DH adopts a protein fold similar to that found in members of the short chain dehydrogenase/reductase (SDR) family, while the enzyme itself represents a previously uncharacterized member of this family. In solution, Ga5DH exists as a tetramer that comprised four identical ∼29 kDa subunits. The catalytic site of Ga5DH shows considerable architectural similarity to that found in other enzymes of the SDR family, but the S. suis protein contains an additional residue (Arg104) that plays an important role in the binding and orientation of substrate. The quaternary complex structure provides the first clear crystallographic evidence for the role of a catalytically important serine residue and also reveals an amino acid tetrad RSYK that differs from the SYK triad found in the majority of SDR enzymes. Detailed analysis of the crystal structures reveals important contributions of Ca2+ ions to active site formation and of specific residues at the C‐termini of subunits to tetramer assembly. Because Ga5DH is a potential target for therapy, our findings provide insight not only of catalytic mechanism, but also suggest a target of structure‐based drug design.