bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermo‐Responsive Copolymers Based on Poly(N‐isopropylacrylamide) and Poly[2‐(methacryloyloxy)ethyl phosphorylcholine]: Light Scattering and Microscopy Experiments
Authors: Cristiano Cláudia M. Z. , Soldi Valdir , Li Chengming , Armes Steven P. , Rochas Cyrille , Pignot‐Paintrand Isabelle , Borsali Redouane 
Published: September 2009

AbstractAqueous self‐assembly of thermosensitive triblock copolymers based on poly(N‐isopropylacrylamide) and poly[2‐(methacryloyloxy)ethyl phosphorylcholine] (PNIPAMm–PMPCn–PNIPAMmand PNIPAMm–PMPCn–S–S–PMPCn–PNIPAMm) were studied using light scattering (SLS and DLS), TEM and fluorescence experiments. These techniques were used to investigate the morphological transition as a function of the temperature, below and above the LCST of the PNIPAM, at various triblock copolymer concentrations ranging from dilute to semi‐dilute regimes. Below the LCST and at low concentrations, aqueous solutions show micellar behavior, while above the LCST self‐assembly leading to large nanoparticles stabilized with PMPC chains. Such behavior is the onset of a gel‐like phase transition observed at higher concentrations.magnified image
Poly[ethylene‐co‐(vinyl alcohol)]‐graft‐Poly(ε‐caprolactone) by Reactive Extrusion, 2 – Parameter Analysis
Authors: Zhao Yanchao , Becquart Frédéric , Chalamet Yvan , Chen Jianding D. , Taha Mohamed 
Published: September 2009

AbstractEVOH‐g‐PCL were prepared by a solvent‐free reactive extrusion process using a co‐rotating twin screw extruder. Kinetic simulations were made of selected reaction conditions at 185 °C. Changes in the screw rotation rate resulted in evolution of the residence time distribution and slightly changed the monomer conversion. An increase of the [OH]0/[Cl]0 ratio made the reactive system more viscous and decreased the overall pumping capacities of the extruder. Increase of the mean residence time, combined with a positive kinetic effect of [OH]0 increase, leaded to an important increase in conversion. For all the conducted experiments, equivalent distribution dispersions and good agreements between calculated conversion and those measured were obtained. An increase in temperature from 185 to 200 °C resulted in total conversion.magnified image
A Solvent‐Assisted Compression Molded of Poly(L‐lactide)/Hydroxyapatite Electrospun Fibers for Robust Engineered Scaffold Systems
Authors: Luong Nguyen Dang , Moon Ik‐Sang , Nam Jae‐Do 
Published: September 2009

AbstractIn an attempt to enhance the biocompatibility and mechanical strength of fibrous polymeric scaffold systems, nanocrystalline hydroxyapatite (HAp) particles were incorporated into the electrospun poly(L‐lactide) (PLLA) fibers and then mechanically interlocked using a vapor‐phase solvent adsorption method. The solvent‐assisted compression molding substantially increased the tensile strength (from 4.61 to 12.63 MPa) and mechanical modulus (from 50.6 to 627.7 MPa) of the fibrous scaffold, which maintained the interstitial space between the fibers to allow the facile transport of nutrients and waste during cell growth and polymer biodegradation. Macrometer‐sized pores (ca. 100–400 µm) were introduced into the scaffolds in a controlled fashion using the salt leaching/gas forming technique to give desired space for a facile cell implantation and growth. Overall, the developed methodology allows the polymer‐based scaffold systems to be tailored for various applications in light of surface characteristics, mechanical strength, and pore size of engineered scaffolds.magnified image
A Magnetically Tunable Colloidal Crystal Film for Reflective Display
Authors: Zhu Cun , Chen Liangshui , Xu Hua , Gu Zhongze 
Published: September 2009

AbstractA general approach to fabricate a magnetic field responsive colloidal crystal film has been developed. This is carried out by depositing monodisperse Fe3O4/PS composite magnetic nanospheres on the surface of an agarose‐gel coated substrate. The optical properties of the resultant film can be easily controlled by an external magnetic field, which is caused by assembly of the magnetic nanospheres and alteration of the interparticle distance. With the help of a designed array of small magnets, both the color and pattern of the film can be conveniently modulated and the tuning range covers almost the whole visible spectrum. This work will be important for the potential application of monodisperse magnetic nanospheres in fabricating novel sensors, displays and optoelectronic devices.magnified image
Essential tremor — Neurodegenerative or nondegenerative disease towards a working definition of ET
Authors: Deuschl Günther , Elble Rodger 
Published: September 2009

AbstractEssential tremor (ET) is a syndrome of tremor in posture and movement, but recent studies have revealed additional cerebellar motor disturbances, cognitive disturbances, personality changes, hearing loss, and olfactory deficits. Even dementia and shortened life expectancy were found in one cohort. Recent postmortem studies have found limited Lewy body pathology in some patients and Purkinje cell loss with torpedoes and Bergmann gliosis in others. These findings have led to the hypothesis that ET is a syndrome produced by at least two neurodegenerative diseases with more widespread clinical consequences than previously appreciated. We review the evidence for and against this hypothesis and conclude that studies purporting to support this hypothesis have failed to control for age‐associated comorbidities, depression, medications, and other confounding factors. We propose the alternative hypothesis that abnormal neuronal oscillation is the fundamental abnormality in ET, and the well‐documented cerebellar signs and symptoms, the controversial non‐motor signs, and even the cerebellar pathology of ET could be caused by this oscillation. A major problem for many studies is the lack of a diagnostic gold standard. Lacking such a standard, we propose a subclassification of ET into three categories: hereditary ET, sporadic ET, and senile ET, which we believe will help researchers resolve many of the controversies in this field. © 2009 Movement Disorder Society
Modelling instabilities in triaxial testing on unsaturated soil specimens
Authors: Buscarnera Giuseppe , Nova Roberto 
Published: September 2009

AbstractThe paper presents a theoretical approach to deal with mechanical instabilities in unsaturated soils. Towards this goal, the concept of test controllability is extended to a hydro‐mechanically coupled framework. A constitutive approach based on the introduction of hydraulic generalized stress–strain variables is first adopted, in order to better describe suction effects on the mechanical behaviour of soil. The mathematical consequences of hydro‐mechanical coupling are presented next and two indices are defined to identify the onset of an instability. Possible instability modes linked to saturation processes are discussed. It is shown that the way in which the hydraulic variables are controlled in tests on unsaturated soil specimens is the key factor for the possible occurrence of instabilities and the consequent loss of test controllability. It is shown in particular that unsaturated soil specimens are prone to instability when an externally controlled water flux is injected into the specimen (inundation). This result could in part explain the sudden collapse of soil specimens subjected to wetting under constant applied stresses, which is observed both in the laboratory and in the field. Copyright © 2009 John Wiley & Sons, Ltd.
Iterative strong coupling of dimensionally heterogeneous models
Authors: Leiva Jorge S. , Blanco Pablo J. , Buscaglia Gustavo C. 
Published: September 2009

AbstractIn this article we address decomposition strategies especially tailored to perform strong coupling of dimensionally heterogeneous models, under the hypothesis that one wants to solve each submodel separately and implement the interaction between subdomains by boundary conditions alone. The novel methodology takes full advantage of the small number of interface unknowns in this kind of problems. Existing algorithms can be viewed as variants of the ‘natural’ staggered algorithm in which each domain transfers function values to the other, and receives fluxes (or forces), and vice versa. This natural algorithm is known as Dirichlet‐to‐Neumann in the Domain Decomposition literature. Essentially, we propose a framework in which this algorithm is equivalent to applying Gauss–Seidel iterations to a suitably defined (linear or nonlinear) system of equations. It is then immediate to switch to other iterative solvers such as GMRES or other Krylov‐based method, which we assess through numerical experiments showing the significant gain that can be achieved. Indeed, the benefit is that an extremely flexible, automatic coupling strategy can be developed, which in addition leads to iterative procedures that are parameter‐free and rapidly converging. Further, in linear problems they have the finite termination property. Copyright © 2009 John Wiley & Sons, Ltd.
The preparation of novel silica modified polyimide membranes: synthesis, characterization, and gas separation properties
Authors: Boroglu Mehtap Safak , Gurkaynak Mehmet Ali 
Published: September 2009

AbstractIn this study, new monomers having siloxane groups were synthesized as an intermediate for preparation of siloxane modified polyimide polymers. Then with these monomers, the synthesis of uncrosslinked and crosslinked polyimide–siloxane hybrid polymer membranes were achieved. The purposes of the preparation of modified polyimides were to modify the thermal and chemical stability, and mechanical strength of polyimides, and to improve the gas separation properties of polymers. The new diamine monomer having siloxane groups was prepared from 3,5‐diaminobenzoic acid (3,5‐DABA) and 3‐aminopropyltrimethoxysilane (3‐APTMS) in N‐methyl‐2‐pyrollidone (NMP) at 180°C. The modified polyimide membranes having different amount of siloxane groups were synthesized from pyromellitic dianhydride (PMDA), 4,4‐oxydianiline (ODA), and 3,5‐diaminobenzamido‐N‐propyltrimethoxy silane (DABA/PTMS) in NMP using a two‐step thermal imidization process. The synthesis of modified polyimide membranes were characterized by Fourier transform infrared spectroscopy (FTIR). The thermal analysis of the polyimides were carried out by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Water absorption and swelling experiments were also carried out for the investigation of structural properties of polymers. FTIR observations confirmed that the polyimide membranes with new diamine intermediate were successfully obtained. Thermal analysis showed that the uncrosslinked copolyimides exhibited two glass transition temperatures, indicating that they were separated microphases and it was found that all the modified copolyimides had showed higher glass transition temperature (Tg) than unmodified polyimides. The separation properties of the prepared polyimide membranes were also characterized by permeability for O2 and N2 gases and ideal selectivity values were calculated. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis of PLLA‐PEOMA comb‐block‐comb type molecular brushes based on AGET ATRP and ring‐opening polymerization
Authors: Wu Dongxia , Zhao Chuanzhuang , Tian Jia , Zhao Hanying 
Published: September 2009

AbstractBACKGROUND: Molecular brushes are types of macromolecules with densely grafted side chains on a linear backbone. The synthesis of macromolecular brushes has stimulated much interest due to their great potential in applications in various fields. Poly(L‐lactide)–poly(ethylene glycol) methyl ether methacrylate (PLLA‐PEOMA) comb‐block‐comb molecular brushes with controlled molecular weights and narrow molecular weight distributions were successfully synthesized based on a combination of activator generated by electron transfer (AGET) atom transfer radical polymerization (ATRP) and ring‐opening polymerization. The synthetic route is a combination of the ‘grafting through’ method for AGET ATRP of the PEOMA comb block and the ‘grafting from’ method for the synthesis of the PLLA comb block. Poly(2‐hydroxyethyl methacrylate) (PHEMA) was synthesized by ATRP, and PLLA side chains and PEOMA side chains were grown from the backbones and the terminal sites of PHEMA, respectively.RESULTS: The number‐average degrees of polymerization of PLLA chains and poly[poly(ethylene glycol) methyl ether methacrylate] (PPEOMA) comb blocks were determined using 1H NMR spectroscopy, and the apparent molecular weights and molecular weight distributions of the brush molecules were measured using gel permeation chromatography. The crystallization of the components in the comb‐block‐comb copolymers was also investigated. The crystallization of PLLA side chains is influenced by PLLA chain length and the content of PPEOMA in the molecular brushes. The comb‐block‐comb copolymer composed of hydrophobic PLLA and hydrophilic PEOMA can self‐assemble into a micellar structure in aqueous solution.CONCLUSION: A combination of AGET ATRP and ring‐opening polymerization is an efficient method to prepare well‐defined comb‐block‐comb molecular brushes. The physical properties of the molecular brushes are closely related to their structures. Copyright © 2009 Society of Chemical Industry
Crosslinking of mixtures of diglycidylether of bisphenol‐A with 1,6‐dioxaspiro[4.4] nonan‐2,7‐dione initiated by tertiary amines: III. Effect of hydroxyl groups on network formation
Authors: Fernández‐Francos Xavier , Cook Wayne D , Salla Josep M , Serra Àngels , Ramis Xavier 
Published: September 2009

AbstractBACKGROUND: Blends of epoxy resin oligomers, diglycidylether of bisphenol‐A (DGEBA), and a bislactone, 1,6‐dioxaspiro[4.4]nonan‐2,7‐dione (s(γBL)), were anionically copolymerized using two tertiary amines as anionic initiators. Their curing rheology and gelation behaviour were studied to provide a more comprehensive knowledge of the curing of these previously studied systems.RESULTS: The activation energy for gelation was found to be similar to that previously measured using differential scanning calorimetry and appeared to increase in the presence of the bislactone. The reaction rate during copolymerization of DGEBA with s(γBL) was slower than DGEBA homopolymerization alone because the alkoxide attack on the epoxide is faster than the reaction of the carboxylate ion and the epoxy group. The effect of the initiator type on the gel conversion was small and was presumably due to differences in the kinetic chain length caused by amine regeneration from the quaternary amine. For the same initiator and at a constant ratio of DGEBA/s(γBL), an increase in the hydroxyl concentration of the DGEBA oligomer raised the gel conversion. For a DGEBA oligomer with low hydroxyl levels, an increase in the concentration of s(γBL) increased the gel conversion; however, for a DGEBA oligomer with high hydroxyl levels, increasing s(γBL) concentration decreased the gel conversion.CONCLUSION: These results are interpreted in terms of the effect of initiation rate and chain transfer rate on the kinetic chain length. The glass transition temperature of the gel was found to be controlled by the fraction of the aliphatic s(γBL) and the amount of plasticizing sol in the matrix. Copyright © 2009 Society of Chemical Industry
Polyaniline–vanadium oxide hybrid hierarchical architectures assembled from nanoscale building blocks by homogeneous polymerization
Authors: Zhang Chuanqin , Wang Li , Peng Hongrui , Chen Kezheng , Li Guicun 
Published: September 2009

AbstractBACKGROUND: Polyaniline–vanadium oxide hybrid materials have been much researched due to their potential applications in lithium batteries. Although many methods have been reported for the fabrication of conventional polyaniline–vanadium oxide hybrid materials by in situ oxidative polymerization/intercalation of aniline in V2O5 and by layer‐by‐layer approaches, studies on polyaniline–vanadium oxide hybrid nanostructures have been rare.RESULTS: Polyaniline–vanadium oxide hybrid hierarchical architectures assembled from nanoscale building blocks, such as nanoplates and nanobelts, have been synthesized by a one‐step hydrothermal homogeneous reaction between aniline and peroxovanadic acid without the aid of any surfactant or template. The influences of synthesis parameters, i.e. reaction time, temperature and medium, on the morphologies of the polyaniline–vanadium oxide hybrid nanostructures have been investigated. With increasing reaction time/temperature, the alignment of nanoplates in the hierarchical architectures becomes gradually dense.CONCLUSION: The formation mechanism of the polyaniline–vanadium oxide hybrid hierarchical architectures involves a one‐step precipitation–polymerization–assembly process. The method may be applicable for the synthesis of other conducting polymer–vanadium oxide hybrid nanostructures. Copyright © 2009 Society of Chemical Industry
A three‐way proteomics strategy allows differential analysis of yeast mitochondrial membrane protein complexes under anaerobic and aerobic conditions
Authors: Helbig Andreas O. , de Groot Marco J. L. , van Gestel Renske A. , Mohammed Shabaz , de Hulster Erik A. F. , Luttik Marijke A. H. , Daran‐Lapujade Pascale , Pronk Jack T. , Heck Albert J. R. , Slijper Monique 
Published: September 2009

AbstractTo investigate the effect of anaerobiosis on the Saccharomyces cerevisiae mitochondrial proteome and the formation of respiratory chain and other protein complexes, we analyzed mitochondrial protein extracts that were enriched from lysates of aerobic and anaerobic steady‐state chemostat cultures. We chose an innovative approach in which native mitochondrial membrane protein complexes were separated by 1‐D blue native PAGE, which was combined with quantitative analysis of each complex subunit using stable isotope labeling. LC‐FT(ICR)‐MS/MS analysis was applied to identify and quantify the mitochondrial proteins. In addition, to establish if changes in mitochondrial complex composition occurred under anaerobiosis, we investigated the 1‐D blue native PAGE protein migration patterns by Pearson correlation analysis. Surprisingly, we discovered that under anaerobic conditions, where the yeast respiratory chain is not active, the respiratory chain supercomplexes, such as complex V dimer, complex (III)2(IV)2 and complex (III)2(IV) were still present, although at reduced levels. Pearson correlation analysis showed that the composition of the mitochondrial complexes was unchanged under aerobic or anaerobic conditions, with the exception of complex II. In addition, this latter approach allowed screening for possible novel complex interaction partners, since for example protein Aim38p, with a yet unknown function, was identified as a possible component of respiratory chain complex IV.
Y‐shaped diblock copolymer with epoxy‐based block of poly(glycidyl methacrylate): Synthesis, characterization, and its morphology study
Authors: Zhang Bao , Li Yapeng , Ai Peng , Sa Zhongpeng , Zhao Yili , Li Meng , Wang Di , Sha Ke 
Published: September 2009

AbstractA Y‐shaped diblock copolymer with a functional block poly(glycidyl methacrylate) was synthesized via the combination of enzymatic ring‐opening polymerization (eROP) and atom transfer radical polymerization (ATRP). The synthetic procedure involved eROP of ε‐caprolactone (ε‐CL) in the presence of biocatalyst Novozyme 435 and initiator 1H,1H,2H,2H‐perfluoro‐1‐octaoxy, subsequently the resulting poly(ε‐caprolactone) (PCL) was converted to a macroinitiator by esterification of it with 2,2‐dichloro acetyl chloride, and finally the ATRP of glycidyl methacrylate (GMA) was conducted at 60 °C with CuCl/2,2′‐bipyridine as the catalyst system. By this process, we obtained copolymers with a controlled molecular weight and a low polydispersity. The structure and composition of the obtained polymers were characterized by H NMR, GPC, and IR. Linear first‐order kinetics, linearly increased molecular weight with conversion, and low polydispersities were observed for the ATRP of GMA. The thermal properties of the copolymer were characterized by differential scanning calorimetry. The self‐assembly behavior of the Y‐shaped block copolymer was also investigated in different solvents and at different concentrations. The aggregates of various morphologies (spheres, worm‐like patterns, nanowell patterns, and dendritic patterns) were observed. It was found that solvents remarkably influenced the morphologies of the films spin‐coated from the corresponding solutions. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5509–5526, 2009
Creating Anti‐Reflective Nanostructures on Polymers by Initial Layer Deposition before Plasma Etching
Authors: Wendling Irmina , Munzert Peter , Schulz Ulrike , Kaiser Norbert , Tünnermann Andreas 
Published: September 2009

AbstractThe generation of nanostructures by initial layer deposition and plasma etching offers a simple and cost‐effective method for imparting broadband anti‐reflection properties to polymer optics. In this study, we have investigated the possibility of controlling the structure growth on the cycloolefin polymer Zeonex®. It has been found that the geometry of the emerging nanostructures can be adjusted from “island‐like,” through “sponge‐like,” to “pinholes” merely by changing the thickness of the initial layer before the etching step. However, not all structure types provided a satisfactory transmittance enhancement. Only when the initial layer thickness and the etching time were matched in such a way that a certain material/air filling factor range and a sufficient structure depth were obtained could an outstanding anti‐reflection effect be realized.
Characterization of intrinsically disordered proteins with electrospray ionization mass spectrometry: Conformational heterogeneity of α‐synuclein
Authors: Frimpong Agya K. , Abzalimov Rinat R. , Uversky Vladimir N. , Kaltashov Igor A. 
Published: September 2009

AbstractConformational heterogeneity of α‐synuclein was studied with electrospray ionization mass spectrometry by analyzing protein ion charge state distributions, where the extent of multiple charging reflects compactness of the protein conformations in solution. Although α‐synuclein lacks a single well‐defined structure under physiological conditions, it was found to sample four distinct conformational states, ranging from a highly structured one to a random coil. The compact highly structured state of α‐synuclein is present across the entire range of conditions tested (pH ranging from 2.5 to 10, alcohol content from 0% to 60%), but is particularly abundant in acidic solutions. The only other protein state populated in acidic solutions is a partially folded intermediate state lacking stable tertiary structure. Another, more compact intermediate state is induced by significant amounts of ethanol used as a co‐solvent and appears to represent a partially folded conformation with high β‐sheet content. Protein dimerization is observed throughout the entire range of conditions tested, although only acidic solutions favor formation of highly structured dimers of α‐synuclein. These dimers are likely to present the earliest stages in protein aggregation leading to globular oligomers and, subsequently, protofibrils. Proteins 2010. © 2009 Wiley‐Liss, Inc.