bluuebunny/crossref_metadata_2025_split huggingface dataset:
2,7‐Di‐tert‐butylnaphtho[1,8‐cd][1,2]dithiole 1,2‐dioxides: Thermally Stable, Photochemically Active vic‐Disulfoxides
Authors: Grainger Richard S. , Patel Bhaven , Kariuki Benson M. 
Published: May 2009

AbstractBulking up: The thermal barrier to rearrangement of a vic‐disulfoxide is significantly increased through steric buttressing about the (O)SS(O) bond. Whereas the title compounds represent the most thermally stable vic‐disulfoxides known to date, they also undergo a novel photomediated epimerization at room temperature (see scheme).magnified image
Phase morphology and clay distribution of poly(trimethylene terephthalate)/polypropylene/montmorillonite nanocomposites
Authors: Xue Mei‐Ling , Li Peng 
Published: May 2009

AbstractPoly(trimethylene terephthalate) (PTT)/polypropylene (PP) blend nanocomposites were prepared by melt mixing of PTT, PP, and organically modified clay. The phase morphologies of the PTT/PP nanocomposites and the distribution of the clay in the nanocomposites were investigated using scanning electron microscopy, transmission electron microscopy (TEM), and wide angle X‐ray diffraction. When PP is the dispersed phase, the domain size of the PP phase is decreased significantly with increasing the clay content from 0 to 5 wt %. In contrast, when PTT is the dispersed phase, the dimension of the PTT phase is a little larger in the presence of 2 wt % clay compared with the case of without clay. TEM observations indicate that the clay is mainly distributed at the phase interfaces along the phase borderlines. In addition, some intercalated clay tactoids (multilayer particles) are observed in the PTT matrix whereas no discernable clay particles can be found in the PP phase, indicating that the affinity of clay with PTT is higher than with PP. In the presence of 5 wt % PP‐graft‐maleic anhydride, the phase morphology is much finer, and most clay is exfoliated and distributed at the phase interfaces forming phase borderlines in polygonal shape. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The partial replacement of silica or calcium carbonate by halloysite nanotubes as fillers in ethylene propylene diene monomer composites
Authors: Pasbakhsh Pooria , Ismail Hanafi , Fauzi Mohd Noor Ahmad , Bakar Azhar Abu 
Published: May 2009

AbstractThe effect of partial replacement of silica or calcium carbonate (CaCO3) by halloysite nanotubes (HNTs) on the curing behavior, tensile properties, dynamic mechanical properties, and morphological characteristics of ethylene propylene diene monomer (EPDM) composites was studied. Five different compositions of EPDM/Silica/HNT and EPDM/CaCO3/HNT compounds (i.e. 100/30/0, 100/25/5, 100/15/15, 100/5/25, and 100/0/30 parts per hundred rubber (phr)) were prepared on a two‐roll mill. The results indicated that the replacement of CaCO3 by HNTs increased the tensile strength, elongation at break (Eb), and tensile modulus of composites from 0 to 30 phr of HNTs whereas for silica, the maximum tensile strength and Eb occurred at 5 phr loading of HNTs with an enhanced stress at 300% elongation (M300). The curing results show that, with replacement of silica or CaCO3 by HNTs, the cure time (t90) and cure rate (CRI) were decreased and increased, respectively. Scanning electron microscopy investigation confirmed that co‐incorporation of 5 phr of HNTs with silica would improve the dispersion of silica and enhanced the interactions between fillers and EPDM matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of formation conditions on the structure and properties of nanocomposite alginate fibers
Authors: Boguń Maciej , Mikołajczyk Teresa , Rabiej Stanisław 
Published: May 2009

AbstractThe conditions for producing nanocomposite fibers composed of calcium alginate, containing a hydroxyapatite nanoadditive were devised and the rheological, sorptive, and strength properties of these fibers, as well as their porous and supramolecular structure were subjected to analysis. It has been concluded that the presence of the HAp nanoadditive in the material of alginate fibers decreases their susceptibility to distortion in the drawing stage, which results in their tenacity properties being lower by 2cN/tex than of the fibers with no nanoadditive. The obtained nanocomposite fibers are characterised by a tenacity value exceeding 26 cN/tex, accompanied by high sorptive and water‐retention properties of 90% and the even distribution of the nanoadditive on the fiber surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Supercritical carbon dioxide‐assisted loosening preparation of dry leather
Authors: Yang Qiuyan , Qin Shufa , Chen Jiafu , Ni Wei , Xu Qun 
Published: May 2009

AbstractThe physical modification of the dry leather using supercritical carbon dioxide (SC‐CO2) was studied in this article. A series of loosening processes of the leather fibers were carried out by changing the experimental conditions such as experimental pressure, experimental temperature, and time. The samples were characterized by scanning electronic microscopy (SEM), Brunauer–Emmett–Teller (BET) and X‐ray diffraction (XRD). SEM images show that samples were loosened by SC‐CO2 and the leather fibers in micron size arrange more orderly after treatment. The BET surface area of treated samples increase from 1.67 m2/g to 6.33 m2/g with the changing of conditions. The optimal treatment conditions were determined. Moreover, XRD patterns indicate that aggregation structure of collagen fibers in the sample was altered by SC‐CO2, and it can be found that the loosening of leather mostly happened in amorphous regions of collagen fibers. Besides, the percent breaking elongation of the samples was examined by means of a tensile analyzing test, and it indicates that the elongation at break of all the treated samples in SC‐CO2 can increase to 128.2% compared with 95.9% of the original ones. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Emulsion polymerization of styrene with amphiphilic random copolymer as surfactant: Predominant droplet nucleation
Authors: Liu Li , Liu Xiao‐Li , Han Ye , Chen Qing‐Rui , Yu Jing‐Feng , Liu Feng‐Qi 
Published: May 2009

AbstractAmphiphilic random copolymer consisting of monomeric units of poly (butyl acrylate) and poly (maleic acid salt) was synthesized and characterized. The emulsion polymerization kinetics of styrene stabilized by this copolymer was investigated. The influencing factors, including polymeric surfactant concentration, initiator concentration and polymerization temperature, were systematically studied. The kinetic data show that the polymerization rate (RP) increased with the increase of the polymeric surfactant concentration ([S]) and polymerization temperature (T). At the higher [S], droplets nucleation and micelle nucleation coexisted in the polymerization system; at the lower [S], only the droplets nucleation process existed. The polymerization did not follow Smith‐Ewart Case II kinetics. Dynamic light scatter and transmission electron microscope were utilized to measure the sizes and shapes of the particles, respectively. It would be speculated that a kind of large heterogeneous particles with multiple‐active‐sites was formed in the polymerization system. The increasing of RP with increasing initiator concentration ([KPS]) was rapid at a medium [KPS], but the slowly increasing was observed at a lower or higher [KPS]. It was attributed to the barrier effect of the polymeric surfactant around the monomer droplets. The polymerization activation energy was 60.29 kJ/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Microphase separation behavior on the surfaces of poly(dimethylsiloxane)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) diblock copolymer coatings
Authors: Luo Zheng‐Hong , Yu Hai‐Jiang , Zhang Wei 
Published: May 2009

AbstractMicrophase separation behavior on the surfaces of poly(dimethylsiloxane)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PHFBMA) diblock copolymer coatings was investigated. The PDMS‐b‐PHFBMA diblock copolymers were successfully synthesized via atom transfer radical polymerization (ATRP). The chemical structure of the copolymers was characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopy. Surface composition was studied by X‐ray photoelectron spectroscopy. Copolymer microstructure was investigated by atomic force microscopy. The microstructure observations show that well‐organized phase‐separated surfaces consist of hydrophobic domain from PDMS segments and more hydrophobic domain from PHFBMA segments in the copolymers. The increase in the PHFBMA content can strengthen the microphase separation behavior in the PDMS‐b‐PHFBMA diblock copolymers. And the increase in the annealing temperature can also strengthen the microphase separation behavior in the PDMS‐b‐PHFBMA diblock copolymers. Moreover, Flory‐Huggins thermodynamic theory was preliminarily used to explain the microphase separation behavior in the PDMS‐b‐PHFBMA diblock copolymers.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and characterization of polyurethane hybrids: Influence of the polydimethylsiloxane linear chain and silsesquioxane cubic structure on the thermal and mechanical properties of polyurethane hybrids
Authors: Madhavan K. , Reddy B. S. R. 
Published: May 2009

AbstractThe structural effects of polydimethylsiloxane (PDMS) or polyhedral oligosilsesquioxanes (POSSs) on the thermomechanical properties of polyurethane (PU) networks were studied. An ester–amine‐functionalized silsesquioxane and a PDMS macromer were synthesized, and the macromer (10 wt %) was crosslinked with the PU prepolymer to obtain PU networks. The synthesized macromers and hybrids were characterized with Fourier transform infrared, 1H‐NMR, 13C‐NMR, and 29Si‐NMR spectroscopy techniques. The influence of POSS cubes on the thermal and mechanical properties of the polymer network films was studied comparatively with the similarly functionalized PDMS linear chain via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) measurements. The degradation pattern of the POSS‐incorporated PU nanocomposites was almost the same as that of the PU network synthesized from the linear PDMS macromer. The differences in the char yields and activation energies of the hybrids reflected the enhancement of the thermal properties of the nanohybrids. The TGA and DSC curves of the macromers suggested that the thermal properties of the macromers not only depended on either the PDMS or POSS inorganic core but also depended on the organic peripheral attached to the inorganic core. The glass‐transition temperatures of the nanohybrids were higher than those of the linear‐PDMS‐incorporated hybrids. The storage modulus values increased 3‐fold upon the incorporation of POSS rigid groups into the PU hybrids in comparison with the flexible PDMS‐chain‐incorporated PU hybrids. The DMA measurements showed a long‐range rubbery plateau region for all the PU hybrids, with high storage modulus and tan δ values showing the structural homogeneity of the crosslinked networks. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and properties of poly(ether imide)s derived from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and aromatic ether–diamines
Authors: Hsiao Sheng‐Huei , Yang Chin‐Ping , Chen Yung‐Chung , Wang Hui‐Ming , Guo Wenjeng 
Published: May 2009

AbstractA series of poly(ether imide)s (PEIs) with light colors and good mechanical properties were synthesized from 2,5‐bis(3,4‐dicarboxyphenoxy)biphenyl dianhydride and various aromatic ether–diamines via a conventional two‐step polymerization technique that included ring‐opening polyaddition at room temperature to poly(amic acid)s (PAAs) followed by thermal imidization. The precursor PAAs had inherent viscosities ranging from 0.71 to 1.19 dL/g and were solution‐cast and thermally cyclodehydrated to flexible and tough PEI films. All of the PEI films were essentially colorless, with ultraviolet–visible absorption cutoff wavelengths between 377 and 385 nm and yellowness index values ranging from 10.5 to 19.9. These PEIs showed high thermal stabilities with glass‐transition temperatures of 206–262°C and decomposition temperatures (at 10% weight loss) higher than 478°C. They also showed low dielectric constants of 3.39–3.72 (at 1 MHz) and low water absorptions below 0.85 wt %. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of network relaxation on void propagation and failure in isotactic polypropylene at large strain
Authors: Na Bing , Lv Ruihua , Xu Wenfei 
Published: May 2009

AbstractThe important role of network relaxation in the voiding and fracture toughness of isotactic polypropylene (iPP) has been explored with video‐aid tensile tests, two‐dimensional small‐angle X‐ray scattering (2D‐SAXS) measurements, and morphological observations. The results indicated that macroscopic volume dilatation related to voiding became lower during large deformation of iPP sample with rich γ phase (denoted as γ‐iPP) cooled at 1°C/min, compared with one with exclusive α form (referred to α‐iPP) quenched in air. Furthermore, void propagation perpendicular to the tensile direction, demonstrated by Guinier approximation analysis of 2D‐SAXS results, was suppressed to a large extent in such a γ‐iPP sample. Less network relaxation, resulted from its peculiar crystalline and amorphous phases, was responsible for lower volume dilatation and slower void propagation in the γ‐iPP sample. Meanwhile, less network relaxation and suppressed transverse void propagation contributed to higher toughness in the γ‐iPP sample. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Photoluminescence of solution processed poly n‐vinyl carbazole films
Authors: Chung P. S. , Holloway P. H. 
Published: May 2009

AbstractThe photoluminescence (PL) of poly n‐vinyl carbazole (PVK) films formed by solution processing was investigated. PVK films were formed by spincasting onto bare glass or glass covered by films of indium tin oxide (ITO) and poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate)ethylene (PEDOT : PSS). Some of the spincast films were redissolved in chloroform solvent and redried both in the absence or presence of an electric field (6000 V/cm). The broad aggregate PL peak near 410 nm exhibited both blue and red shifts dependent upon the processing conditions. These shifts in PL were attributed to changes in the excimer populations associated with the molecular conformation of adjacent carbazole groups. The PL data were deconvoluted into two component peaks representing two excimers associated with overlap of only one (partial or P) or full overlap (F) of both aromatic rings on adjacent carbazole groups. It was concluded that the excimer population was dependent on the amount of residual solvent left in the film after processing and upon the type of substrate. The mechanism(s) controlling the molecular configurations was discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Free‐radical retrograde‐precipitation copolymerization of vinyl acetate and acrylic acid
Authors: Caneba Gerard T. , Xu Zhiyong , Dar Yadunandan L. 
Published: May 2009

AbstractFree‐radical chain polymerization kinetics of vinyl acetate (VA) and acrylic acid (AA) exhibit some unusual control features. The VA radicals have a high rate of chain transfer leading to relatively sluggish propagation rates. Polymerization of AA, however, is prone to autoacceleration behavior in bulk, solution, and precipitating media. Thus, conventional statistical copolymerization of VA and AA would result in the preferential formation of high AA content copolymer. However, when the reaction medium is chosen in such a way that the copolymer precipitates above the lower critical solution temperature (LCST), propagation control and even monomer sequence control are obtained. Under these conditions, when the VA charge is much greater than AA, a tapered block copolymer (VA‐t‐AA) is obtained. We report a single stage polymerization process for the synthesis of such materials. The presence of VA‐t‐AA products is verified by emulsification, solubility, fractionation, size exclusion chromatography, NMR, and thermal analyses. In addition, propagation control can virtually eliminate formation of bimodal MWD and random/homopolymer materials that are associated with various chain transfer mechanisms in conventional polymerization routes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Resol/montmorillonite nanocomposites obtained by in situ polymerization
Authors: Rivero Guadalupe , Vázquez Analía , Manfredi Liliana B. 
Published: May 2009

AbstractNanocomposites based on resol resin and layered silicates were obtained by in situ polymerization. An increment in the viscosity and in the content of free formaldehyde in the prepolymer with the addition of clay was observed. It could be attributed to the entrance of small phenol molecules into the galleries modifying the concentration of reagent enabled to react outside the clay galleries.The composites were cured by temperature and it was observed that the type of clay affect their dispersion in the polymer. The unmodified Cloisite® Na+ montmorillonite (CNa) was the best dispersed in the polymeric matrix, whereas the modified montmorillonites (MMTs) showed an interlayer contraction after curing. It seems to be due to the loss of modifiers from the clay or to the different rate of curing inside and outside the galleries. In addition, the composite containing CNa presented higher crosslinking density than the others with modified MMTs. More adhesive strength was observed in that composite as well. It was related with the void content and the polarity of the samples. These results were compared with the ones obtained when the nanocomposites were synthesized by mixing the clay with the prepolymer. The nanocomposites with the addition of CNa showed similar properties independent of the way of synthesis used. However, it seems that the modified clays are better dispersed by mixing with the prepolymer than by in situ polymerization. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The Developing Left Superior Cervical Ganglion of Pacas (Agouti paca)
Authors: Melo Samanta Rios , Nyengaard Jens Randel , da Roza Oliveira Felipe , Ladd Fernando Vagner Lobo , Abrahão Luciana Maria Bigaram , Machado Márcia R.F. , Sasahara Tais H.C. , de Melo Mariana Pereira , Ribeiro Antonio Augusto C.M. 
Published: May 2009

AbstractIn this study the main question investigated was the number and size of both binucleate and mononucleate superior cervical ganglion (SCG) neurons and, whether post‐natal development would affect these parameters. Twenty left SCGs from 20 male pacas were used. Four different ages were investigated, that is newborn (4 days), young (45 days), adult (2 years), and aged animals (7 years). By using design‐based stereological methods, that is the Cavalieri principle and a physical disector combined with serial sectioning, the total volume of ganglion and total number of mononucleate and binucleate neurons were estimated. Furthermore, the mean perikaryal (somal) volume of mononucleate and binucleate neurons was estimated using the vertical nucleator. The main findings of this study were a 154% increase in the SCG volume, a 95% increase in the total number of mononucleate SCG neurons and a 50% increase in the total volume of SCG neurons. In conclusion, apart from neuron number, different adaptive mechanisms may coexist in the autonomic nervous system to guarantee a functional homeostasis during ageing, which is not always associated with neuron losses. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
The Collagen Receptor DDR2 Is Expressed During Early Cardiac Development
Authors: Goldsmith Edie C. , Zhang Xiadong , Watson James , Hastings Josh , Potts Jay D. 
Published: May 2009

AbstractDiscoidin Domain Receptor 2 (DDR2) is a receptor tyrosine kinase which has been shown to regulate cell migration upon binding its ligand, collagen. Expression studies determined that DDR2 mRNA and protein are present in the atrioventricular canal during epithelial‐mesenchymal transformation (EMT) and the receptor is expressed in both activated endothelial and migrating mesenchymal cells in vivo. Anat Rec, 2010. © 2009 Wiley‐Liss, Inc.
The effect of calorie restriction on growth and development in silkworm, Bombyx mori
Authors: Li Yijia , Chen Keping , Yao Qin , Li Jun , Wang Yong , Liu Haijun , Zhang Chiyu , Huang Guoping 
Published: May 2009

AbstractCaloric restriction (CR) is known to extend the life span in different species from yeast to mammals. In this report, a simple organism silkworm (Bombyx mori) was used to study the effect of moderate CR on the growth and development processes of insects. Here we show that an extension of life span upon moderate CR was observed in the silkworm. The total protein level in the 5th instar larvae hemolymph appeared to decline significantly under CR. SDS‐PAGE analysis showed that the influence of CR was sex‐dependent. The CR effects on female animals were much more significant than on the males. The MALDI‐TOF MS study identified 16 proteins that expressed differentially among six groups of the male or female larvae fed at different time frequencies. Four of them, storage protein 1 (SP1), arylphorin (SP2), imaginal disk growth factor (IDGF), and 30‐kDa lipoprotein, showed significant differences. It was demonstrated that these four proteins were up‐regulated when the larvae were over‐fed and down‐regulated when the larvae were less‐fed. © 2009 Wiley Periodicals, Inc.
The mode of action of venom from the endoparasitic wasp Pimpla hypochondriaca (Hymenoptera: Ichneumonidae) involves Ca+2‐dependent cell death pathways
Authors: Rivers David B. , Dani M. Paulina , Richards Elaine H. 
Published: May 2009

AbstractThe endoparasitoid Pimpla hypochondriaca injects venom during oviposition to condition its lepidopteran hosts. Venom is a complex mixture of proteins and polypeptides, many of which have been identified as enzymes, including phenoloxidase, endopeptidase, aminopeptidase, hydrolase, and angiotensin‐converting enzyme. Constituents of the venom have been shown to possess cytolytic and paralytic activity, but the modes of action of factor(s) responsible for exerting such effects have not been deciphered. In this study, we examined the mode of action of isolated venom using cultured cells (BTI‐TN‐5B1‐4). A series of blockage and inhibition assays were performed using a potent inhibitor (phenylthiourea, PTU) of venom phenoloxidase, and anti‐calreticulin antibodies. Monolayers exposed to venom alone were highly susceptible with more than 84.6±2.3% dead within 15 min. Susceptible cells displayed a retraction of cytoplasmic extensions, rounding, and swelling prior to lysis in more than half (55.7±1.7%) of the dying cells. Within 15 min of exposure to venom, cells displayed qualitative increases in [Ca+2]i as evidenced by staining with the calcium‐sensitive probe fluo‐4 AM, and mitochondrial membrane potential (ΔΨm) was undetectable by 5 min post‐treatment with venom. These venom‐mediated changes occurred regardless of whether an external source of calcium was present, or whether venom was pre‐treated with PTU. In contrast, venom toxicity was attenuated by treatment with anti‐calreticulin antibodies. Not only did fewer cells die when exposed to antibody‐treated venom but also cell swelling diminished and no increases in intracellular calcium were detected. A possible mode of action for the venom is discussed. © 2009 Wiley Periodicals, Inc.