bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nonisothermal crystallization and multiple melting behaviors of β‐nucleated impact‐resistant polypropylene copolymer
Authors: Li Xiaoxi , Wu Haiyan , Chen Jingwei , Yang Jinghui , Huang Ting , Zhang Nan , Wang Yong 
Published: April 2012

AbstractAs a substitute of isotactic polypropylene in applications requiring excellent fracture resistance, impact‐resistant polypropylene copolymer (IPC) has attracted much attention in recent years. In this study, a highly effective β‐form nucleating agent (β‐NA; an aryl amide compound) was introduced into IPC, and our attention was focused on the nonisothermal crystallization and subsequent melting behaviors of the nucleated samples. The nonisothermal crystallization behaviors were investigated on the basis of the different cooling rates and different concentrations of β‐NA with differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), and polarized optical microscopy. The results show that both the cooling rate and concentration of β‐NA greatly determined the nonisothermal crystallization process and subsequent multiple melting behaviors. Further results show that the multiple melting behaviors were related to the transition in β crystallites and those between the β and α crystallites. The morphologies of the dispersed particles and the supermolecular structure of the matrix were characterized with scanning electron microscopy. Finally, the effect of the β‐NA concentration on the fracture resistance of IPC was evaluated by measurement of the notched Izod impact strength. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Dependence of the liquid absorption behavior of nonwovens on their material and structural characteristics: Modeling and experiments
Authors: Das Dipayan , Pradhan Arun Kumar , Pourdeyhimi Behnam 
Published: April 2012

AbstractNonwovens are widely used as liquid absorbent products. Baby diapers, sanitary napkins, adult incontinence pads, oil sorbents, wet wipes, and wound dressings, to name a few, are excellent examples of the use of nonwovens as absorbent media. The performance of nonwoven absorbent media is determined by its liquid absorption behavior, which is characterized by the capacity of absorption and the rate of absorption. In this article, we report on the effects of the physical characteristics of the constituent fibers and the internal structure of the nonwovens on their liquid absorption behavior. A theoretical model of liquid absorption behavior of nonwovens was developed, and this model was verified with a set of experimental results obtained on real nonwoven materials. The nonwoven materials were prepared with polyester fibers with different cross‐sectional sizes and their liquid absorption properties were measured with the gravimetric absorbency testing system. We observed that the size of fiber cross sections and the porosity of the nonwovens played very important roles in determining their absorbent capacity and rate of absorption. The results of the experiments were discussed in light of the theoretical model. The theoretical results were found to be in good agreement with the experimental results. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Fabrication and characterization of multilayer SiO2/polymethacrylic acid/polypyrrole composites and hollow polypyrrole microspheres
Authors: Wang Wenqin , Lu Linchao , Chen Tianyang , Rao Mian 
Published: April 2012

AbstractMethacrylic acid was polymerized on the 3‐(methacryloxy)propyl trimethoxysilane‐modified silica core. The carboxylic acid groups of polymethacrylic acid (PMAA) not only provide the “active‐sites” for growth of the pyrrole monomers but also act as doping acids for polypyrrole (PPy). By in situ polymerization route, SiO2/PMAA/PPy multilayer composites and hollow PPy microspheres with controllable shell thickness were fabricated. The morphologies, sizes, and structures of the nanocomposites were investigated in detail by transmission electron microscopy, scanning electron microscopy, Fourier‐transform infrared spectra, X‐ray photoelectron spectroscopy, and thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Comparison of the properties of compacted and porous lamellar chitosan–xanthan membranes as dressings and scaffolds for the treatment of skin lesions
Authors: Bellini Márcia Zilioli , Pires Ana Luíza Resende , Vasconcelos Mariana Oliveira , Moraes Ângela Maria 
Published: April 2012

AbstractCompacted and porous lamellar membranes of xanthan (Xn) and chitosan (Ch) at mass ratios of 1 : 1 and 1.2 : 0.8 were prepared and tested to verify possible applications in the treatment of skin lesions. All membranes were prepared by complexation of the polysaccharides in solution and subsequent casting. The porous membranes were obtained by adding either Tween 80 or Pluronic F68 to the polysaccharide complexes before casting. Membranes prepared in the absence of surfactants at a mass ratio of Xn to Ch of 1 : 1 proved ideal for use as wound dressings, as they were thin (around 0.10 mm in thickness) and transparent and had low in vitro cytotoxicity to L929 cells, a tensile strength at break of 25 MPa, water absorption after 24 h of around 86 g/g and simulated body fluid absorption of 16% and adequate stability in the presence of the same solutions. Membranes prepared at the mass ratio of Xn to Ch of 1 : 1 in the presence of Pluronic F68 showed the most favorable characteristics for application as scaffolds for tissue engineering. These membranes consisted of a matrix with interconnected pores which were distributed homogeneously throughout the structure and had a thickness of 1.84 mm, high capacity for FBS uptake (around 18 g/g) and cell culture medium uptake (8.6 g/g), a loss of mass in the culture medium of 33% after 144 h, and low in vitro toxicity to L929 cells. In conclusion, membranes of Ch and Xn produced in the presence or absence of the surfactant Pluronic F68 have a high potential for use as scaffolds in tissue engineering or as dermal dressings, respectively, whereas in contrast, membranes prepared in the presence of Tween 80, regardless of the mass ratio of Xn to Ch, were very cytotoxic to L929 cells and therefore were not appropriate for any of the proposed applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
New method for coupling collagen on biodegradable polyurethane for biomedical application
Authors: He Xianyun , Zhai Zhichen , Wang Yingjun , Wu Gang , Zheng Zhiwen , Wang Qunfang , Liu Yang 
Published: April 2012

AbstractA two‐step method was used in this article to synthesize a novel biodegradable polyurethane (PU) composed by L‐lysine ethyl ester diisocyanate (LDI) hard segment, poly(ε‐caprolactone) diols (PCL‐diol) soft segment and 1,4:3,6‐dianhydro‐D‐sorbitol (isosorbide) chain extender. FTIR, 1H‐NMR results revealed the products had typical PU structures. GPC result showed that the number average molecular weight of the PU was 36,800 with the heterodisperse index of 2.18. DSC result displayed the PU melting temperature was 42°C. Surface aminolyzing of the PU membrane was performed by reacting it with 1,3‐propanediamine under alkaline condition. Then, type I collagen was grafted on the PU surface by EDC/NHS coupling method. Rhodamine B isothiocyanate (RBITC) fluorescence spectrum presented that both amino group (NH2) and type I collagen were successfully introduced on the PU surface. Furthermore, ninhydrin analysis showed that the maximum surface density of amino groups was 11.4 × 10−7 mol/cm2 after aminolyzing in 12% 1,3‐propanediamine aqueous solution for 1 h. Cell viability experiments indicated both PU‐NH2 and PU‐Col had low cytotoxicity and supported the ATDC5 cell's proliferation on them. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of amphiphilic triblock copolymers for the formation of magnesium fluoride (MgF2) nanoparticles
Authors: Bas Serkan , Chatterjee Uma , Soucek Mark D. 
Published: April 2012

AbstractA series of amphiphilic poly(2‐hydroxyethyl methacrylate)‐b‐polydimethylsiloxane‐b‐poly(2‐hydroxyethyl methacrylate) (pHEMA‐b‐PDMS‐b‐pHEMA) (A‐B‐A) triblock copolymers were synthesized from three different carbinol‐terminated polydimethylsiloxanes with varying molecular weight. A carbinol‐terminated polydimethylsiloxane was modified with 2‐bromoisobutyryl bromide to obtain a macroinitiator. The block copolymers were characterized by NMR, GPC, and dynamic light scattering (DLS). Reverse micelles of a copolymer were formed in mixture of benzene/methanol solution which served as nanoreactors for the synthesis of magnesium fluoride (MgF2) nanoparticles. The MgF2 was prepared via chemical precipitation using magnesium chloride and potassium fluoride as reactants. The MgF2‐triblock copolymer composites were synthesized as a function of MgF2–weight ratio (0.5, 5, and 10 wt%) in copolymer. The MgF2 colloids were dissolved in three organic solvents: methanol, isopropanol, and tetrahydrofuran. The polymer nanoparticles were characterized by DLS, transmission electron microscopy, thermogravimetric analysis, and X‐ray diffraction (XRD) analysis. The formation of MgF2 crystals was observed by XRD. Particle size and particle size distribution showed significant changes in different solvents. The thermal stability of MgF2 colloids increased as the amount of nanoparticle increased in polymeric matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Biodegradable composites from polyester and sugar beet pulp with antimicrobial coating for food packaging
Authors: Li Weili , Coffin David R. , Jin Tony Z. , Latona Nicolas , Liu Cheng‐Kung , Liu Bo , Zhang Jinwen , Liu LinShu 
Published: April 2012

AbstractTotally biodegradable, double‐layered antimicrobial composite films were introduced for food packaging. The substrate layers of the sheets were prepared from poly(lactic acid) (PLA) and sugar beet pulp (SBP) or poly (butylene adipate‐co‐terephthalate (PBAT) and SBP by a twin‐screw extruder. The active layer consisting of antimicrobial in either PLA or chitosan was formed on the surfaces of the substrates by solution coating followed by solvent evaporation. Air‐coupled ultrasonic evaluation and microscopic examination showed a homogeneous structure for the composite sheets. Mechanical analysis and acoustic emission demonstrated the double‐layered composites possessing appropriate tensile strength and fracture characteristics for the use as light weight‐bearing materials. The release of Nisaplin® or allyl isothiocyanate (AIT) effectively suppressed the growth of Listeria monocytogenes and Salmonella cells, respectively; the co‐release of Nisaplin® and AIT played a synergistic effect on inhibition of L. monocytogenes. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Aliphatic polycarbonate‐based polyurethane elastomers and nanocomposites. I. The influence of hard‐segment content and macrodiol‐constitution on bottom‐up self‐assembly
Authors: Špírková Milena , Poręba Rafał , Pavličević Jelena , Kobera Libor , Baldrian Josef , Pekárek Michal 
Published: April 2012

AbstractAliphatic polycarbonate‐based polyurethane (PC‐PU) elastomers as well as their nanocomposites with organic‐modified clay (bentonite for organic system) were synthesized. Macrodiols (MD) (randomly copolymerized aliphatic PC‐glycols of molecular weight of about 2000: T5652, T4672, and T4692), hexamethylene diisocyanate, and butane‐1,4‐diol were used as starting materials. Solid‐state NMR and Fourier transform infrared spectroscopy, small‐angle X‐ray scattering, wide‐angle X‐ray diffraction, atomic force microscopy, and transmission electron microscopy were used for studying the bottom‐up self‐assembly of building units from the segmental level up that of organized structures of micrometer sizes. Contents of hard segments formed by the reaction of chain extender with diisocyanate plays a dominant role for the degree of ordering and related phenomena, while the MD chain has only limited effect on PC‐PU properties. The spectroscopy and scattering experiments suggest that bentonite particles incorporate well in the structure and promote the ordering of hard segment domains in PC‐PU matrix as compared with the nanofiller‐free analogue. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Why the interactions of fast ions with foils are distinct from charge exchange
Authors: Träbert E. 
Published: April 2012

AbstractThe intensity patterns of some Rydberg line series in the X‐ray spectra of foil‐excited fast ion beams bear a resemblance to patterns seen with SN remnants or after charge exchange (CX). Closer scrutiny of the ion‐foil interaction process reveals why this is no more than a chance resemblance, because the underlying processes are very different. However, electron beam ion traps are suitable for CX observations (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exospheric solar wind charge exchange as seen by XMM‐Newton
Authors: Carter J.A. , Sembay S. , Read A.M. 
Published: April 2012

AbstractWe review a selection of recent papers describing solar wind charge exchange emission occurring in the Earth's exosphere as seen by the X‐ray observatory XMM‐Newton. We discuss the detection of this emission, the occurrence with respect to the solar cycle and solar activity, and various spectral signatures observed. We also describe a model developed to predict the X‐ray signal from exospheric charge exchange as would be detected by XMM‐Newton, given the upstream solar wind conditions obtained from in situ solar wind monitors (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prototyping a global soft X‐ray imaging instrument for heliophysics, planetary science, and astrophysics science
Authors: Collier M.R. , Porter F.S. , Sibeck D.G. , Carter J.A. , Chiao M.P. , Chornay Dj. , Cravens T. , Galeazzi M. , Keller J.W. , Koutroumpa D. , Kuntz K. , Read A.M. , Robertson I.P. , Sembay S. , Snowden S. , Thomas N. 
Published: April 2012

AbstractWe describe current progress in the development of a prototype wide field‐of‐view soft X‐ray imager that employs Lobster‐eye optics and targets heliophysics, planetary, and astrophysics science. The prototype will provide proof‐of‐concept for a future flight instrument capable of imaging the entire dayside magnetosheath from outside the magnetosphere. Such an instrument was proposed for the ESA AXIOM mission (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Solar system X‐rays from charge exchange processes
Authors: Dennerl K. , Lisse C.M. , Bhardwaj A. , Christian D.J. , Wolk S.J. , Bodewits D. , Zurbuchen T.H. , Combi M. , Lepri S. 
Published: April 2012

AbstractWhile X‐ray astronomy began in 1962 and has made fast progress since then in expanding our knowledge about where in the Universe X‐rays are generated by which processes, it took one generation before the importance of a fundamentally different process was recognized. This happened in our immediate neighborhood, when in 1996 comets were discovered as a new class of X‐ray sources, directing our attention to charge exchange reactions. Charge exchange is fundamentally different from other processes which lead to the generation of X‐rays, because the X‐rays are not produced by hot electrons, but by ions picking up electrons from cold gas. Thus it opens up a new window, making it possible to detect cool gas in X‐rays (like in comets), while all the other processes require extremely high temperatures or otherwise extreme conditions. After having been overlooked for a long time, the astrophysical importance of charge exchange for the generation of X‐rays is now receiving increased general attention. In our solar system, charge exchange induced X‐rays have now been established to originate in comets, in all the planets from Venus to Jupiter, and even in the heliosphere itself. In addition to that, evidence for this X‐ray emission mechanism has been found at various locations across the Universe. Here we summarize the current knowledge about solar system X‐rays resulting from charge exchange processes (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Approximating the X‐ray spectrum emitted from astrophysical charge exchange
Authors: Smith R.K. , Foster A.R. , Brickhouse N.S. 
Published: April 2012

AbstractCharge exchange (CX), both onto ions in the solar wind and potentially in other astrophysical contexts, can create X‐ray emission lines largely indistinguishable from those created in collisional or photoionized plasmas. The prime distinguishing characteristic is in the distinctly different line ratios generated by the CX process. A complete astrophysical model of the process would require a vast number of atomic calculations; we describe here an approximate approach that will allow astronomers to evaluate the likely contribution of CX to an observed spectrum. The method relies upon an approximate calculation of the CX cross section paired with detailed atomic structure calculations used to determine the emission lines. Simulated spectra based on observed solar wind CX data are shown for both current (Suzaku) and near‐term (Astro‐H) missions (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of glycyrrhizin on biliary transport and hepatic levels of glutathione in rats
Authors: Xu Ruijuan , Zhang Xueying , Yang Jin , Liu Xiaoquan , Davey Andrew K , Wang Jiping 
Published: April 2012

ABSTRACTThe purpose of the current study was to determine whether glycyrrhizin (GL) maintains hepatic glutathione (GSH) levels by inhibiting GSH biliary secretion in normal rats. The effects of glycyrrhizin on hepatic glutathione content, bile flow and biliary secretion of glutathione were examined. Because glutathione is a substrate for multidrug resistance associated protein‐2 (Mrp2/ABCC2), the inhibitory effects of GL on Mrp2 in isolated perfused rat liver and in Mrp2‐expressing Sf9 membrane vesicles were also examined using the Mrp2 substrate methotrexate (MTX) and estradiol‐17‐β‐glucuronide (E217G). The hepatic content of glutathione in rats following GL perfusion (43.7 µmol/l) in isolated liver perfusion and GL intravenous treatment (25 mg/kg) was significantly higher than that for the control. A marked and dose‐dependent decrease in the excretion of glutathione was observed. In addition, the secretion rate of MTX was decreased by 57% in isolated liver perfusion in GL‐treated rats. Moreover the ATP‐dependent uptake of E217G by Mrp2 membrane vesicles was decreased by 75.9% in the 20 µm GL group and by 60.5% in the 2 µm GL group. In conclusion, glycyrrhizin increases hepatic glutathione content possibly through inhibition of Mrp2 which then reduces the biliary excretion of glutathione. Copyright © 2012 John Wiley & Sons, Ltd.
Comparison ofSeggerand other methods for segmentation and rigid‐body docking of molecular components in Cryo‐EM density maps
Authors: Pintilie Grigore , Chiu Wah 
Published: April 2012

AbstractSegmentation and docking are useful methods for the discovery of molecular components in electron cryo‐microscopy (cryo‐EM) density maps of macromolecular complexes. In this article, we describe the segmentation and docking methods implemented inSegger. For 11 targets posted in the 2010 cryo‐EM challenge, we segmented the regions corresponding to individual molecular components usingSegger. We then used the segmented regions to guide rigid‐body docking of individual components. Docking results were evaluated by comparing the docked components with published structures, and by calculation of several scores, such as atom inclusion, density occupancy, and geometry clash. The accuracy of the component segmentation using Segger and other methods was assessed by comparing segmented regions with docked components. © 2012 Wiley Periodicals, Inc. Biopolymers 97: 742–760, 2012.
A novel environmental chamber for neuronal network multisite recordings
Authors: Biffi E. , Regalia G. , Ghezzi D. , De Ceglia R. , Menegon A. , Ferrigno G. , Fiore G.B. , Pedrocchi A. 
Published: April 2012

AbstractEnvironmental stability is a critical issue for neuronal networks in vitro. Hence, the ability to control the physical and chemical environment of cell cultures during electrophysiological measurements is an important requirement in the experimental design. In this work, we describe the development and the experimental verification of a closed chamber for multisite electrophysiology and optical monitoring. The chamber provides stable temperature, pH and humidity and guarantees cell viability comparable to standard incubators. Besides, it integrates the electronics for long‐term neuronal activity recording. The system is portable and adaptable for multiple network housings, which allows performing parallel experiments in the same environment. Our results show that this device can be a solution for long‐term electrophysiology, for dual network experiments and for coupled optical and electrical measurements. Biotechnol. Bioeng. 2012; 109: 2553–2566. © 2012 Wiley Periodicals, Inc.
Development of a novel ER stress based selection system for the isolation of highly productive clones
Authors: Kober Lars , Zehe Christoph , Bode Juergen 
Published: April 2012

AbstractMost biotherapeutic drugs are recombinant monoclonal antibodies which are mostly produced in monoclonal cell lines derived from Chinese hamster ovary (CHO) cells. Various clones expressing a monoclonal recombinant antibody were analyzed and a correlation of the antibody concentration and the relative mRNA level of calreticulin (CALR), glucose‐regulated protein 78 and 94 kDa (GRP78, GRP94) and spliced X‐box binding protein 1 (XPB1) was observed. By means of these results we were motivated to establish a novel selection system based on endoplasmic reticulum (ER) stress, which allows the rapid identification and isolation of high‐expressing clones out of a pool mainly consisting of low‐ and medium‐producing cells. Several ER stress responsive elements were tested with the aid of a recombinase mediated cassette exchange (RMCE) procedure. Very surprisingly, only GRP78 reporter constructs were strongly stimulated upon antibody expression. Furthermore we found that GRP78 reporter constructs are very suitable to reflect the level of antibody expression (IgG) in recombinant CHO cells. Based on these results, it is concluded, that the novel ER stress based selection system developed during this study is suitable to identify and isolate clones with a high level of antibody expression. Biotechnol. Bioeng. 2012; 109: 2599–2611. © 2012 Wiley Periodicals, Inc.