bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and assessment of the advanced graft copolymers obtained from Hibiscus sabdariffa biomass
Authors: Chauhan Ashish , Kaith Balbir 
Published: August 2011

AbstractIn this article, the morphological transformation in Hibiscus sabdariffa stem fiber through graft copolymerization with effective ethyl acrylate (EA) and its binary vinyl monomeric mixtures using ceric ammonium nitrate—nitric acid initiator system has been reported. Different reaction parameters such as temperature, time, initiator concentration, monomer concentration, and pH were optimized to obtain the maximum graft yield (117.3%). The optimized reaction parameters were then used to screen the additive effect of EA with n‐butyl acrylate (BA), acrylic acid (AA), and 4‐vinyl pyridine (4‐VP) in binary vinyl monomer mixtures on percentage grafting, properties, and the behavior of the fiber. The graft copolymers were characterized by FTIR, SEM, XRD, TGA, and DTA techniques and evaluated for physico‐chemical changes. With increase in the Pg a significant physico‐chemico‐thermal resistance, miscibility in organic solvents, hydrophobicity were found to increase, whereas crystallinity, crystallinity index, dye‐uptake, and hydrophylicity decreased, however, the cellulose form I remained unchanged. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis of cationic UV‐curable methacrylate copolymers and properties of the cured films of their composites with alicyclic epoxy resin
Authors: Tang Chunyi , Liu Weiqu 
Published: August 2011

AbstractCationic UV‐curable methacrylate copolymers consisting of glycidyl methacrylate, iso‐butyl methacrylate, and 2,2,3,4,4,4‐hexafluorobutyl methacrylate were synthesized, and their structures were characterized by FTIR, 1H NMR, and 13C NMR. A series of UV‐cured composite films based on the synthesized copolymers and an alicyclic epoxy resin, 3,4‐epoxycyclohexylmethyl‐3,4‐epoxycyclohexanecarboxylate (CE) were obtained through photopolymerization. Their surface contact angle, chemical ability, gloss, light transmittance, thermal behavior, micromorphology, and shrinkage were investigated. Results indicated that these cured resins showed excellent gloss and visible light transmittance; after the combination of the copolymers and CE, and in the presence of fluorine in the curing systems they exhibited relatively fine water resistance, chemical, and thermal stability. It was observed that these copolymers could decrease the degree of the volume shrinkage to CE. The UV‐curable materials may have promising applications in optical fiber coatings, flip chip and Organic Light‐Emitting Diode (OLED) packing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Cone calorimeter study of inorganic salts as flame retardants in polyurethane adhesive with limestone filler
Authors: Lindholm Johan , Brink Anders , Wilén Carl‐Eric , Hupa Mikko 
Published: August 2011

AbstractA cone calorimeter was used to test inorganic water‐releasing and low‐melting compounds as flame retardants in polyurethane adhesive samples. Sodium metasilicate pentahydrate, potassium carbonate mixed with silica gel, sodium hydrogen carbonate, calcium oxalate monohydrate, zinc and magnesium chloride mixed with potassium chloride, aluminium and magnesium hydroxides, ammonium polyphosphate (APP), sodium and potassium phosphates were tested. These additives were used to partially (10–20%) replace the limestone used as a filler in the adhesive. Thermogravimetric analysis was used to study decomposition and melting of the inorganic compounds. The results showed that sodium metasilicate monohydrate formed a protective layer of sodium silicate on the sample surface, significantly delaying the time to ignition. Addition of APP resulted in the lowest overall heat release rate curve. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Comparison of UF synthesis by alkaline‐acid and strongly acid processes
Authors: Ferra João M. M. , Henriques Ana , Mendes Adélio M. , Costa Mário Rui N. , Carvalho Luisa H. , Magalhães Fernão D. 
Published: August 2011

AbstractThis work discusses two processes for producing urea‐formaldehyde (UF) resins. One is the alkaline‐acid process, which has three steps: usually an alkaline methylolation followed by an acid condensation and finally the addition of a final amount of urea. The other process, the strongly acid process, consists of four steps, in which the first step involves a strongly acid condensation followed by an alkaline methylolation, a second condensation under a moderately acid pH and finally, methylolation and neutralization under a slight alkaline pH. Two resins were produced using the two above described processes. The molecular weight distribution (MWD) of the resins was monitored off‐line by GPC/SEC and the final resins were characterized by GPC/SEC and HPLC. These studies showed that the two resins differ greatly in chemical structure, composition, viscosity, and reactivity. The monitoring of MWD indicated that the first condensation under a strongly acid environment leads to the production of a polymer with a distinctly different chemical structure, therefore increasing the flexibility of polymer synthesis and opening the way to the improvement of end‐use properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Crystallization, dispersion behavior and the induced properties through forming a controllable network in the crosslinked polyester‐SiO2 nanocomposites
Authors: Guo Wang Yu , Chuan Ke Yang 
Published: August 2011

AbstractThe poly(ethylene terephthalate) (PET) crosslinked copolymers (G‐PET) with glycerol (GC) and their novel nanocomposite samples (GNPET) were reported and investigated. The nanoparticle dispersion behavior was creatively stabilized with the crosslinked network. Several interesting properties and phenomena including the abnormal crystallization behavior of GNPET samples were presented. Results of differential scanning calorimeter proved that the thermal and crystallization behavior of GNPET samples was effectively tuned with GC load. The obviously enhanced crystallization and nanoparticle homogenous dispersion behavior appeared at 2 wt % SiO2 and 0.2 wt % GC load. Polarized optical microscopy (POM) results showed that the spherulite growth rate of the GNPET samples with 0.1 wt % GC load sharply decreased from 0.0562 to 0.0157 μm s−1 with 0.5 wt % GC load. As GC load increased, the spherulite size of GNPET samples decreased greatly so as to be much smaller than that of pure PET nanocomposites. Water absorbing experiments presented that the higher GC load created the lower water diffusion behavior but higher barrier against water, gas, and light. A model was proposed to state the network immobilization effect on the nanoparticle dispersion, and the restraining effect on PET chain mobility and crystal size growth which were related to the above properties. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Morphology and properties of nylon 6 and high density polyethylene blends in presence of nanoclay and PE‐g‐MA
Authors: Mallick Sumana , Kar Prativa , Khatua B. B. 
Published: August 2011

AbstractIn this study, we report the synergistic effect of nanoclay and maleic anhydride grafted polyethylene (PE‐g‐MA) on the morphology and properties of (80/20 w/w) nylon 6/high density polyethylene (HDPE) blend. Polymer blend nanocomposites containing nanoclay with and without compatibilizer (PE‐g‐MA) were prepared by melt mixing, and their morphologies and structures were examined with scanning electron microscopy (SEM) and wide angle X‐ray diffractometer (WAXD) study. The size of phase‐separated domains decreased considerably with increasing content of nanoclay and PE‐g‐MA. WAXD study and transmission electron microscopy (TEM) revealed the presence of exfoliated clay platelets in nylon 6 matrix, as well as, at the interface of the (80/20 w/w) nylon 6/HDPE blend–clay nanocomposites. Addition of PE‐g‐MA in the blend–clay nanocomposites enhanced the exfoliation of clays in nylon 6 matrix and especially at the interface. Thus, exfoliated clay platelets in nylon 6 matrix effectively restricted the coalescence of dispersed HDPE domains while PE‐g‐MA improved the adhesion between the phases at the interface. The use of compatibilizer and nanoclay in polymer blends may lead to a high performance material which combines the advantages of compatibilized polymer blends and the merits of polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Mechanical, barrier, and interfacial properties of biodegradable composite films made of methylcellulose and poly(caprolactone)
Authors: Khan Ruhul A. , Salmieri Stephane , Dussault Dominic , Sharmin Nusrat , Lacroix Monique 
Published: August 2011

AbstractMethylcellulose (MC) films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol, and 0.025% Tween®80. Poly(caprolactone) (PCL) films were prepared by compression molding from its granules. Biodegradable composite films were fabricated using MC film as reinforcing agent and PCL as the matrix material by compression molding. One layer of MC film was reinforced with two layers of PCL films. The MC content in the composites was varied from 10 to 50% by weight. Mechanical, barrier, and degradation properties of PCL, MC, and composite films were evaluated. The values of puncture strength (PS), puncture deformation (PD), viscoelasticity (Y) coefficient, and water vapor permeability (WVP) of the composites (50% MC content) were found to be 124.3 N/mm, 3.2 mm, 31%, and 2.6 g·mm/m2·day·kPa, respectively. Oxygen transmission rate (OTR) of PCL, MC, and composites (50% MC) were found to be 175, 25, 22 cc/m2/d, respectively, which indicated that composite films showed significantly lower OTR than PCL films. Degradation tests of the composite films (50% MC) were performed for 6 weeks in aqueous medium (at 25°C), and it was found that composites lost its mass slowly with time. After 6 weeks, mass and PS of the composites were decreased to 13.4 and 12%, respectively. Composite interface was studied by scanning electron microscopy (SEM). The MC film had good adhesion with PCL matrix during compression molding and suggested strong interface of the composite system. SEM image after 6 weeks of degradation showed some openings in the interface and revealed slow degradation of the MC films. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Structural and mechanical properties of needle‐punched nonwoven reinforced composites in erosive environment
Authors: Tejyan Sachin , Patnaik Amar , Rawal Amit , Satapathy Bhabani K. 
Published: August 2011

AbstractPolypropylene‐based needle‐punched nonwoven reinforced epoxy composites have been fabricated and were evaluated for their thermomechanical response and dry erosion performance. The erosive wear investigations were carried out using silica sand particles as erodent with varying impact velocity, angles of impingement, fiber content, and stand‐off‐distance as the operating variables. Design of experiments (DoE) approach‐based Taguchi analysis was carried out to establish the interdependence of operating parameters and erosion rate. Impingement angle and impact velocity have been found to be the most significant determinants of erosive wear performance of such nonwoven reinforced composites. The composites were also observed to be appreciably resistant to impact content and indentations in addition to exhibiting the absence of any storage‐modulus decay till 60°C accompanied with a nominal increase in the primary transition temperature as revealed from loss‐tangent peaks. The composite with 30 wt % and 40 wt % of nonwoven materials have shown the highest and lowest erosion rates, respectively. The morphology of eroded surfaces was examined by using scanning electron microscopy (SEM) and their possible erosion mechanisms are discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Adsorptive removal of technetium‐99 using macroporous poly(GMA‐co‐EGDMA) modified with diethylene triamine
Authors: Hercigonja Radmila V. , Maksin Danijela D. , Nastasović Aleksandra B. , Trifunović Snežana S. , Glodić Pavle B. , Onjia Antonije E. 
Published: August 2011

AbstractThe possibility of sorption of technetium‐99 in the form of pertechnetate anion (TcO4−) and the sorption kinetics for removing TcO4− from aqueous solution by chelating polymers based on glycidyl methacrylate (GMA) were investigated. Two samples of macroporous crosslinked poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) (PGME), with different amount of the crosslinker (ethylene glycol dimethacrylate, EGDMA), were synthesized by suspension copolymerization and functionalized with diethylene triamine (deta). We propose that nonspecific sorption of pertechnetate anion via electrostatic interactions takes place at the protonated amino groups of macroporous crosslinked copolymer. The results of batch experiments performed at pH 1–14 showed fast sorption kinetics for removing TcO4− by amino‐functionalized PGME‐deta in a wide range of pH, that is, from 1.0 to 9.0. Almost complete removal of TcO4− (91–98%) was reached within 180 min in the stated pH range (1.0–9.0), with the sorption half‐times of under 25 min. The partitioning coefficients of linear adsorption isotherms, with 180‐min equilibrium time, reach the high values of 2130 mL g−1 and 1698 mL g−1 for the two samples of synthesized PGME‐deta. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Immunohistochemical identification and synaptic inputs to the diffuse bipolar cell type DB1 in macaque retina
Authors: Puthussery Theresa , Gayet‐Primo Jacqueline , Taylor W. Rowland , Haverkamp Silke 
Published: August 2011

AbstractDetailed analysis of the synaptic inputs to the primate DB1 bipolar cell has been precluded by the absence of a suitable immunohistochemical marker. Here we demonstrate that antibodies for the EF‐hand calcium‐binding protein, secretagogin, strongly label the DB1 bipolar cell as well as a mixed population of GABAergic amacrine cells in the macaque retina. Using secretagogin as a marker, we show that the DB1 bipolar makes synaptic contact with both L/M as well as S‐cone photoreceptors and only minimal contact with rod photoreceptors. Electron microscopy showed that the DB1 bipolar makes flat contacts at both triad‐associated and nontriad‐associated positions on the cone pedicle. Double labeling with various glutamate receptor subunit antibodies failed to conclusively determine the subunit composition of the glutamate receptors on DB1 bipolar cells. In the IPL, DB1 bipolar cell axon terminals expressed the glycine receptor, GlyRα1, at sites of contact with AII amacrine cells, suggesting that these cells receive input from the rod pathway. J. Comp. Neurol. 519:3640–3656, 2011. © 2011 Wiley‐Liss, Inc.
Dynamic responses of Xenopus retinal ganglion cell axon growth cones to netrin‐1 as they innervate their in vivo target
Authors: Shirkey Nicole J. , Manitt Colleen , Zuniga Liliana , Cohen‐Cory Susana 
Published: August 2011

AbstractNetrin‐1 influences retinal ganglion cell (RGC) axon pathfinding and also participates in the branching and synaptic differentiation of mature RGC axons at their target. To investigate whether netrin also serves as an early target recognition signal in the brain, we examined the dynamic behavior of Xenopus RGC axons soon after they innervate the optic tectum. Time‐lapse confocal microscopy imaging of RGC axons expressing enhanced yellow fluorescent protein demonstrated that netrin‐1 is involved in early axon branching, as recombinant netrin‐1 halted further advancement of growth cones into the tectum and induced back branching. RGC growth cones exhibited differential responses to netrin‐1 that depended on the degree of differentiation of the axon and the developmental stage of the tadpole. Netrin‐1 decreased the total number of branches on newly arrived RGC growth cones at the target, but increased the dynamic branching of more mature arbors at the later developmental stage. To further explore the response of axonal growth cones to netrin, Xenopus RGC axons were followed in culture by time‐lapse imaging. Exposure to netrin‐1 rapidly increased the forward advancement of the axon and decreased the size and expanse of the growth cone, while also inducing back branching. Taken together, the differential in vivo and in vitro responses to netrin‐1 suggest that netrin alone is not sufficient to induce the cessation of growth cone advancement in the absence of a target but can independently modulate axon branching. Collectively, our findings reveal a novel role for netrin on RGC axon branch initiation as growth cones innervate their target. © 2011 Wiley Periodicals, Inc. Develop Neurobiol 72: 628–648, 2012
Toxicity and uptake of TRI- and dibutyltin in Daphnia magna in the absence and presence of nano-charcoal
Authors: Fang Liping , Borggaard Ole K , Holm Peter E , Hansen Hans Christian Bruun , Cedergreen Nina 
Published: August 2011

Abstract
Butyltins (BTs), such as tributyltin (TBT) and dibutyltin (DBT), are toxic to aquatic organisms, but the presence of the strong adsorbent, black carbon (BC), can markedly influence BT toxicity and uptake in organisms. In the present study, the acute toxicity and uptake of TBT and DBT in the crustacean, Daphnia magna, were investigated with and without addition of nano-charcoal at different pHs and water hardnesses. The results showed that the toxicity of TBT and DBT increased by lowering the pH from 8 to 6. This reflects a relatively higher toxicity of cationic BT species than of the neutral species. At pH 6, by enhancing the water hardness of the media from 0.6 to 2.5 mM, the toxicity of TBT and DBT consistently decreased due to competitive binding of bivalent cations (Mg2+, Ca2+) to biotic ligands of D. magna. Furthermore, the toxicity of TBT to D. magna significantly decreased in the presence of nano-charcoal compared with experiments without nano-charcoal at pH 6 and 8, while no significant decrease in toxicity of DBT was observed in the presence of nano-charcoal. This can be attributed to the insignificant decrease of free DBT concentration in the presence of nano-charcoal compared with that for TBT. Conversely, it was observed that more TBT and DBT were taken up in D. magna in the presence of nano-charcoal due to the uptake of TBT or DBT associated with nano-charcoal by Daphnia in gut systems, as seen by light microscopy. This indicated that only free nonadsorbed BTs were toxic to D. magna, at least during short periods of exposure. Environ. Toxicol. Chem. 2011;30:2553–2561. © 2011 SETAC
Proteomic identification of novel targets regulated by the mammalian target of rapamycin pathway during oligodendrocyte differentiation
Authors: Tyler William A. , Jain Mohit Raja , Cifelli Stacey E. , Li Qing , Ku Li , Feng Yue , Li Hong , Wood Teresa L. 
Published: August 2011

AbstractPrevious work from our laboratory demonstrated that the mammalian target of rapamycin (mTOR) is active during and required for oligodendrocyte progenitor cell (OPC) differentiation. Here, we applied an iTRAQ mass spectrometry‐based proteomic approach to identify novel targets of the mTOR pathway during OPC differentiation. Among the 978 proteins identified in this study, 328 (34%) exhibited a greater than 20% change (P < 0.05) in control versus rapamycin‐treated cultures following 4 days of differentiation in vitro. Interestingly, 197 (20%) proteins were elevated in rapamycin‐treated cultures, while 131 (13%) proteins were downregulated by rapamycin. In support of our previous data, inhibiting mTOR caused a dramatic reduction in the expression of myelin proteins. mTOR also was required for the induction of proteins involved in cholesterol and fatty acid synthesis, as well as the expression of many cytoskeletal proteins, cell signaling components, and nuclear/transcriptional regulators. Of particular interest was the identification of several critical mediators of oligodendrocyte differentiation. Specifically, mTOR activity controls the developmentally programmed upregulation of the prodifferentiation factors Fyn and Quaking, whereas the expression of the differentiation repressor Gpr17 was elevated by mTOR inhibition. These data reveal a distinct signature of mTOR‐regulated protein expression during OPC differentiation. © 2011 Wiley‐Liss, Inc.
In vitro modeling of central nervous system myelination and remyelination
Authors: Jarjour Andrew A. , Zhang Hui , Bauer Nina , ffrench‐Constant Charles , Williams Anna 
Published: August 2011

AbstractThis review aims to summarize the current techniques to study myelination and remyelination in culture systems. We attempt to put these into historical context, and to identify the strengths and weaknesses of each approach, which vary depending on the experimental question to be tested. We discuss the difficulty and importance of quantification of myelination and in particular remyelination. Finally, we provide our predictions of how these techniques will and should develop in the future. © 2011 Wiley Periodicals, Inc.
Effects of hypolipidemic agent nordihydroguaiaretic acid on lipid droplets and hepatitis C virus
Authors: Syed Gulam H. , Siddiqui Aleem 
Published: August 2011

Abstract

Hepatitis C virus (HCV) relies on host lipid metabolic pathways for its replication, assembly, secretion, and entry. HCV induces

de novo

lipogenesis, inhibits β-oxidation, and lipoprotein export resulting in a lipid-enriched cellular environment critical for its proliferation. We investigated the effects of a hypolipidemic agent, nordihydroguaiaretic acid (NDGA), on host lipid/fatty acid synthesis and HCV life cycle. NDGA negated the HCV-induced alteration of host lipid homeostasis. NDGA decreased sterol regulatory element binding protein (SREBP) activation and enhanced expression of genes involved in β-oxidation. NDGA inhibited very low-density lipoprotein (VLDL) secretion by affecting mediators of VLDL biosynthesis. Lipid droplets (LDs), the neutral lipid storage organelles, play a key role in HCV morphogenesis. HCV induces accumulation and perinuclear distribution of LDs, whereas NDGA most notably reduced the overall number and increased the average size of LDs. The antiviral effects of NDGA resulted in reduced HCV replication and secretion.

Conclusion:

NDGA-mediated alterations of host lipid metabolism, LD morphology, and VLDL transport appear to negatively influence HCV proliferation. (Hepatology 2011;)
Response of murine bone marrow‐derived mesenchymal stromal cells to dry‐etched porous silicon scaffolds
Authors: Hajj‐Hassan Mohamad , Khayyat‐Kholghi Maedeh , Wang Huifen , Chodavarapu Vamsy , Henderson Janet E. 
Published: August 2011

AbstractPorous silicon shows great promise as a bio‐interface material due to its large surface to volume ratio, its stability in aqueous solutions and to the ability to precisely regulate its pore characteristics. In the current study, porous silicon scaffolds were fabricated from single crystalline silicon wafers by a novel xenon difluoride dry etching technique. This simplified dry etch fabrication process allows selective formation of porous silicon using a standard photoresist as mask material and eliminates the post‐formation drying step typically required for the wet etching techniques, thereby reducing the risk of damaging the newly formed porous silicon. The porous silicon scaffolds supported the growth of primary cultures of bone marrow derived mesenchymal stromal cells (MSC) plated at high density for up to 21 days in culture with no significant loss of viability, assessed using Alamar Blue. Scanning electron micrographs confirmed a dense lawn of cells at 9 days of culture and the presence of MSC within the pores of the porous silicon scaffolds. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011.