bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrospun zein fibers using glyoxal as the crosslinking reagent
Authors: Selling Gordon W. , Woods Kristen Kruger , Biswas Atanu
Published: September 2011

After reaction of zein with glyoxal the resulting electrospun fibers have improved resistance to known zein solvents. Durable fibers with diameters of 0.6 μm could be produced. The reaction between zein and glyoxal was carried out in acetic acid (AcOH) at temperatures between 25 and 60°C at various lengths of time. Gelation would occur after higher extents of reaction. During the course of reaction, solution viscosity increased which increased the diameter of the electrospun fibers produced from these solutions. Gel electrophoresis showed increased molecular weight as the reaction progressed. When 6% glyoxal was allowed to react with zein at 25°C for 6 h, the resulting fibers were durable to AcOH as spun. Other formulations required a second thermal treatment to provide solvent durable fabrics. Fibers displayed different secondary structure utilizing far‐UV circular dichroism spectroscopy. The infrared spectra displayed peaks in the CO region supporting the reaction of glyoxal with hydroxyl groups present on zein. Zein fabrics incorporating glyoxal had modestly improved tensile strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Mechanical and thermal properties of polyphenylene sulfide/multiwalled carbon nanotube composites
Authors: Jiang Zhenyu , Hornsby Peter , McCool Rauri , Murphy Adrian
Published: September 2011

Polyphenylene sulfide (PPS)/multiwalled carbon nanotube (MWCNT) composites were prepared using a melt‐blending procedure combining twin‐screw extrusion with centrifugal premixing. A homogeneous dispersion of MWCNTs throughout the matrix was revealed by scanning electron microscopy for the nanocomposites with MWCNT contents ranging from 0.5 to 8.0 wt %. The mechanical properties of PPS were markedly enhanced by the incorporation of MWCNTs. Halpin‐Tsai equations, modified with an efficiency factor, were used to model the elastic properties of the nanocomposites. The calculated modulus showed good agreement with the experimental data. The presence of the MWCNTs exhibited both promotion and retardation effects on the crystallization of PPS. The competition between these two effects results in an unusual change of the degree of crystallinity with increasing MWCNT content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Miscibility and crystallization behavior of biodegradable poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)/phenolic blends
Authors: Yang Fang , Li Zhisheng , Qiu Zhaobin
Published: September 2011

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV)/phenolic blends are new miscible crystalline/amorphous polymer blends prepared via solution casting method in this work, as evidenced by the single composition dependent glass transition temperature. The measured Tgs can be well fitted by the Kwei equation with a q value of 13.6 for the PHBV/phenolic blends, indicating that the interaction between the two components is strong. The negative polymer–polymer interaction parameter, obtained from the melting depression of PHBV using the Nishi‐Wang equation, indicating the thermal miscibility of PHBV and phenolic. The spherulitic morphology and crystal structure of PHBV/phenolic blends were studied with polar optical microscopy and wide angle X‐ray diffraction compared with those of neat PHBV. It is found that the growth rates of PHBV in the blends are lower than that in neat PHBV at a given crystallization temperature, and the crystal structure of PHBV is not modified by the presence of phenolic in the PHBV/phenolic blends, but the crystallinity decrease with the increasing of phenolic. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Curing characteristics and mechanical properties of rattan‐powder‐filled natural rubber composites as a function of filler loading and silane coupling agent
Authors: Ismail H. , Othman N. , Komethi M.
Published: September 2011

Curing characteristics, tensile properties, morphological studies of tensile fractured surfaces using scanning electron microscopy (SEM), and the extent of rubber filler interactions of rattan‐powder‐filled natural rubber (NR) composites were investigated as a function of filler loading and silane coupling agent (CA). NR composites were prepared by the incorporation of rattan powder at filler loading range of 0–30 phr into a NR matrix with a laboratory size two roll mill. The results indicate that in the presence of silane CA, scorch time (ts2), and cure time (t90) of rattan‐powder‐filled NR composites were shorten, while, maximum torque (MH) increased compared with NR composites without silane CA. Tensile strength and tensile modulus of composites were enhanced whereas elongation at break reduced in the presence of silane CA mainly due to increase in rubber‐filler interaction. It is proven by SEM studies that the bonding between the filler and rubber matrix has improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A combined experimental and theoretical study on vibrational and optical properties of copolymer incorporating thienylene‐dioctyloxyphenyle‐thienylene and bipyridine units
Authors: Ayachi S. , Ghomrasni S. , Alimi K.
Published: September 2011

Optical properties of conjugated copolymer incorporating thienylene‐dioctyloxyphenyle‐thienylene and bipyridine units prepared by Stille coupling reactions in the ground and lowest singlet excited states were calculated with Time Dependent Density Functional Theory (TD‐DFT), CIS/3‐21G*, and semiempirical (ZINDO) methods. The complementarities and the good agreement between theoretical and experimental results have permitted us to describe electronic structure and to predict a correlation between structure and properties of this new copolymer. Then, on the basis of these results, we show that this copolymer could be exploited as an active layer in optoelectronic devices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Characterization of Luffa cylindrica fibers and the effect of water aging on the mechanical properties of its composite with polyester
Authors: Seki Yoldas , Sever Kutlay , Erden Seckin , Sarikanat Mehmet , Neser Gökdeniz , Ozes Cicek
Published: September 2011

Luffa cylindrica of Turkey's Aegean Region was evaluated in terms of fiber characterization and the mechanical properties of its composite with polyester. Characterization of Luffa cylindrica was carried out by Fourier transform infrared spectrophotometer, X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy, and thermogravimetric analysis. Cellulose, hemicellulose, and lignin contents of Luffa cylindirica were also determined. Deconvolutions of XPS data enable determining the distributions of functional groups on the surface of Luffa cylindrica. Luffa cylindrica‐reinforced polyester composite was subjected to water aging under a steam of seawater containing 5% sodium chloride for 170 h at 50°C. After water aging, tensile strength, flexural strength, interlaminar shear strength, and tensile elongation at break values of the composite decreased ∼ 28%, 24%, 45%, and 31%, respectively. However, tensile modulus and flexural modulus did not change significantly. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Positive temperature coefficient effect and interaction based on low‐density polyethylene/graphite powder composites
Authors: Zhang P. , Xue W.T. , Zhao Y. , Liu P.
Published: September 2011

In this article, the positive temperature coefficient (PTC) and interaction based on low‐density polyethylene (LDPE) filled with the loading of graphite (G) powder have been investigated. The dependence of the room temperature resistivity on filler content showed the significant decrease. The PTC behavior enhanced with increasing graphite content but this was not always the case. The maximum PTC effect was observed in LDPE/G composites (G, 45 wt %) with the relatively low room temperature resistivity. The thermal behavior was measured by differential scanning calorimetry (DSC). The structure characteristic for LDPE/G composites was examined by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (SEM), and stress–strain test. The fact was revealed that the slight interaction between LDPE matrix and graphite may lead to change the thermal‐electric properties of the PTC materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Rheological investigation of cure kinetics and adhesive strength of polyurethane acrylate adhesive
Authors: Jaruchattada J. , Fuongfuchat A. , Pattamaprom C.
Published: September 2011

In this work, we used rheological techniques to study both the cure characteristics and the degree of cure of polyurethane acrylate adhesive, a type of reactive adhesive used in hard disk component assembly. These results were then correlated with the tensile shear strengths of adhesives. Here, the cure characteristics of polyurethane adhesive were investigated at isothermal conditions ranging from 25 to 120°C. From the rheological results, the gelation time, the vitrification time, as well as the time required to reach the maximum degree of cure, decreased when increasing the curing temperature. The cure rates of adhesive increased with temperature in three temperature ranges, which were retardation zone, vitrification zone, and reaction‐controlled zone. The cure rates in these zones were controlled by slow diffusion, fast diffusion, and the rate of reaction, respectively. From the temperature sweep of fully‐cured adhesives, we found that the crosslinking level of adhesives increased with curing temperatures at different rates depending on the temperature zones as well. Moreover, the adhesive strength measured by tensile shear test was found to also increase correspondingly with the adhesives' Tg, indicating that the crosslinking level directly affected the adhesive strength. The strong dependence of adhesive strength with crosslinking level indicates that the crosslinking level was essential for high adhesive strength. The correlation of cure characteristics and adhesive strengths at various curing temperatures performed in this study can further provide useful information for planning appropriate curing schemes of polyurethane acrylate adhesives used in electronic and other industries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Characterization of polymeric LB thin films for sensor applications
Authors: Erdogan Matem , Özbek Zikriye , Çapan Rifat , Yagci Yusuf
Published: September 2011

The Quartz Crystal Microbalance (QCM) system is utilized to investigate the relationship between mass uptake and associated swelling for Langmuir‐Blodgett (LB) organic thin films obtained from pyrene end‐capped polystyrene (PS). The study was carried out using three different molecular weights of polymeric chains. The changes in resonance frequency associated with mass changes can be attributed to the swelling behavior of polymeric thin films during vapor absorption. This swelling is due to the capturing of organic vapor molecules in the sensor environment. To quantify real‐time QCM data for swelling, early‐time Fick's law of diffusion was adopted to fit the results, and a good linear relationship was observed between the mass uptake and square root of the swelling time. The diffusion coefficients for swelling were thus obtained from the slopes of the fitting curves and was found to be correlation with the amount of organic vapor content in the cell. It was also observed that diffusion of the organic vapor into higher molecular weight polystyrene thin films are much faster than low molecular weight ones in sensor applications. Diffusion coefficients were found to be 0.2–3.0 × 10−16, 5.0–13 × 10−16, and 1.0–1.6 × 10−15 cm2/s for PS1, PS2, and PS3 LB thin films, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis mechanisms of poly[styrene‐co‐(acrylic acid)]‐supported TiCl4 catalysts modified by magnesium compounds
Authors: Lijun Du , Jian Ye , Jingdai Wang , Binbo Jiang , Yongrong Yang
Published: September 2011

Soluble poly[styrene‐co‐(acrylic acid)] (PSA) modified by magnesium compounds was used to support TiCl4. For ethylene polymerization, four catalysts were synthesized, namely PSA/TiCl4, PSA/MgCl2/TiCl4, PSA/(n‐Bu)MgCl/TiCl4, and PSA/(n‐Bu)2Mg/TiCl4. The catalysts were characterized by a set of complementary techniques including X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and element analysis. Synthesis mechanisms of polymer‐supported TiCl4 catalysts were proposed according to their chemical environments and physical structures. The binding energy of Ti 2p in PSA/TiCl4 was extremely low as TiCl4 attracted excessive electrons from COOH groups. Furthermore, the chain structure of PSA was destroyed because of intensive reactions taking place in PSA/TiCl4. With addition of (n‐Bu)MgCl or (n‐Bu)2Mg, COOH became COOMg‐ which then reacted with TiCl4 in synthesis of PSA/(n‐Bu)MgCl/TiCl4 and PSA/(n‐Bu)2Mg/TiCl4. Although MgCl2 coordinated with COOH first, TiCl4 would substitute MgCl2 to coordinate with COOH in PSA/MgCl2/TiCl4. Due to the different synthesis mechanisms, the four polymer‐supported catalysts correspondingly showed various particle morphologies. Furthermore, the polymer‐supported catalyst activity was enhanced by magnesium compounds in the following order: MgCl2 > (n‐Bu)MgCl > (n‐Bu)2Mg > no modifier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
PLA/chain‐extended PEG blends with improved ductility
Authors: Park Byung‐Sik , Song Jun Cheol , Park Duk Hoon , Yoon Keun‐Byoung
Published: September 2011

Melt blending of polylactic acid (PLA) and a chain‐extended polyethylene glycol (CE‐PEG) have been performed in an effort to toughen the PLA without significant loss of modulus and ultimate tensile strength. The chain‐extended PEG was prepared with melt condensation of a low molecular weight PEG and 4,4′‐methylenebis(phenylisocyanate) (MDI) for enhancement of the molecular weight of PEG. The thermal and mechanical properties, miscibility and phase morphologies of blends were investigated. By using thermal and fracture surface analysis, the blends were found to be a partially miscible system with shifted glass transition temperatures. The addition of CE‐PEG leads to slight decrease in tensile strength and modulus, while the elongation at break is characterized by an important increase (540%), compared with neat PLA and PLA/PEG (low molecular weight PEG, Mn = 35,000). The relative ductility of PLA/CE‐PEG is 40 times higher than that of neat PLA. The brittle fracture of neat PLA was transformed into a ductile fracture by the addition of CE‐PEG. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Optimal geometry design of the coat‐hanger die with uniform outlet velocity and minimal residence time
Authors: Han Wanli , Wang Xinhou
Published: September 2011

In this article a method combining the orthogonal array design and the numerical simulation is used to optimize the geometry parameters of the coat‐hanger die with uniform outlet velocity and minimal residence time. The outlet velocity and the residence time are obtained by simulating the three‐dimensional nonisothermal polymer flow in the coat‐hanger die, while the optimal geometry design is accomplished via the orthogonal array method. The effects of the manifold angle, the land height and the slot gap on the outlet velocity and the residence time are investigated. The results show that the effects of all the three parameters are significant for the outlet velocity. For the residence time, the manifold angle and the slot gap are the significant factors, while the effect of the land height is insignificant. The optimal geometry parameters of the coat‐hanger die achieved in this study are that the manifold angle is 5°, the height land is 70 mm, and the slot gap is 3 mm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effect of nucleation mechanism on complex poly(L‐lactide) nonisothermal crystallization process, part 2: Crystallization kinetics analysis
Authors: Martinelli Andrea , Calì Massimo , D'Ilario Lucio , Francolini Iolanda , Piozzi Antonella
Published: September 2011

In the first part of this article, we reported the crystalline memory effect on the nonisothermal crystallization of poly(L‐lactide). The experiments were carried out by using polymer single crystals growth from dilute solution as standard starting material. In this article (Part II), we have analyzed in detail the effect of the melting condition on the overall crystallization kinetics by applying the Nakamura‐Avrami model to DSC results. The absence or the low concentration of foreign infusible heterogeneous nuclei in our system allowed us to exalt the self‐nuclei role in polymer crystallization, to follow their concentration decrease during the melting process and to find the limiting melting temperature for their disappearance. Below such a temperature, a stable equilibrium number of self‐nuclei was observed, probably deriving from ordered structures, persisting in the melt, and originated from the single crystals thickening process during the polymer dynamic melting in the DSC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Application of nickel (II) complex of dithiocarbamate‐modified starch for anionic dyes removal from aqueous solutions
Authors: Cheng Rumei , Xiang Bo , Li Yijiu
Published: September 2011

The work presents the synthesis of nickel (II) complex of dithiocarbamate‐modified starch (DTCSNi). It is characterized by elemental analysis, infrared spectrum, and thermogravimetry methods. A batch system was applied to study the adsorption of DTCSNi for four anionic dyes removals. The adsorption with respect to the pH was investigated. It is found that the capacity of DTCSNi for each dye is pH dependent, and the adsorption is governed by coordination. At the suitable pH 4, two kinetic models, that is, pseudo‐first‐ and pseudo‐second‐order, were tested to investigate the adsorption process. The kinetic parameters of the models were calculated and discussed. The results suggest that the best fit model is the pseudo‐second‐order equation. The Langmuir–Freundlich model agrees very well with experimental data and the maximum adsorption capacity sequence is AO7 > AG25 > AR18 > AO10. The Fourier transform infrared spectra and thermogravimetric analysis verified the chelating molecular mechanism. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Plasticized and unplasticized PLA/organoclay nanocomposites: Short‐ and long‐term thermal properties, morphology, and nonisothermal crystallization behavior
Authors: Gumus Serap , Ozkoc Guralp , Aytac Ayse
Published: September 2011

The short‐ and long‐term thermal properties, organoclay dispersion state, and the nonisothermal crystallization kinetics of organoclay based nanocomposites of poly(lactic acid) (PLA) and poly(ethylene glycol) (PEG) plasticized PLA were investigated. Differential scanning calorimetry analyses showed that plasticization of PLA/PEG blend was diminished due to physical aging by the time. The change in thermal properties such as glass transition temperature, cold crystallization temperature, and melting temperature was monitored. It was revealed from X‐ray diffraction analyses that in long term, the exfoliated and/or intercalated organoclay structure of nanocomposites observed in short term (just after processing) was differentiated to a tactoidal form (i.e., nonseparated clays). The nonisothermal crystallization behavior and kinetics were examined by using Avrami, Ozawa, and combined Avrami–Ozawa models. Moreover, the nucleating effect of clays was investigated in terms of Gutzow and Dobrewa approaches. It was found out that clays did not act as nucleating agents in plasticized PLA nanocomposites, which was also in good agreement with activation energy values obtained from Kissinger and Takhor models. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation of polydimethylsiloxane‐coated α‐alumina fillers with cold plasma for elastomer thermal interface materials
Authors: Liu Yu , Zhang Li‐Qun , Wang Wen‐Cai , Yu Hai‐Tao , Lu Yong‐Lai
Published: September 2011

A novel method for the organic modification of a ceramic thermal conductive filler (α‐alumina) with cold plasma was developed for the preparation of elastomer thermal interface materials with high thermal conductivities and low moduli. The α‐alumina fillers were first coated with low‐molecular‐weight polydimethylsiloxane (PDMS) by solution dispersion and then treated in argon plasma for different time. The modified α‐alumina fillers were characterized with high‐resolution transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. The results revealed that a thin PDMS film with several nanometers thick was tightly coated on the surface of the alumina filler after plasma treatment, and this thin film could not be removed by 48 h of Soxhlet extraction with n‐hexane at 120°C. Plasma modification of the alumina could dramatically weaken the strength of the filler–filler networks and, thus, remarkably reduce the modulus of the alumina‐filled silicone rubber composites but did not affect the thermal conductivity of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Effects of the compatibility of a polyacrylic block copolymer/tackifier blend on the phase structure and tack of a pressure‐sensitive adhesive
Authors: Nakamura Yoshinobu , Sakai Yu , Imamura Keigo , Ito Keiko , Fujii Syuji , Urahama Yoshiaki
Published: September 2011

Adhesion and viscoelastic properties and morphology of a polyacrylic block copolymer/tackifier blend were investigated. Special rosin ester resins with different weight average molecular weights of 650, 710, 890, and 2160 were used as the tackifier and blended with a polyacrylic block copolymer consisting of poly(methyl methacrylate) and poly(n‐butyl acrylate) blocks at tackifier content levels of 10, 30, and 50 wt %. The compatibility decreased with an increase in molecular weight. From TEM observation, the number of formed agglomerates of the tackifier with sizes on the order of several tens of nanometers increased with increasing tackifier content and molecular weight of the tackifier in the range from 650 to 890. For the tackifier with a molecular weight of 2160, micrometer‐sized agglomerates were observed. The storage modulus at low temperature and the glass transition temperature of adhesive measured by a dynamic mechanical analysis increased dependent on the number of formed nanometer sized agglomerates. Tack was measured using a rolling cylinder tack tester over wide temperature and rolling rate ranges, and master curves were prepared in accordance with the time‐temperature superposition law. Tack and peel strength were optimum at a blend combination of intermediate compatibility, i.e., the molecular weight of 890. These optimum properties were correlated to maximal values of the storage modulus at room temperature and the glass transition temperature. Therefore, it was found that these features of blend properties are strongly affected by the nanometer sized agglomerates of tackifier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Stab resisting behavior of polymeric resin reinforced p‐aramid fabrics
Authors: Kim Hodong , Nam Inwoo
Published: September 2011

The stab resistant performance of p‐aramid fabrics reinforced with thermoplastic LDPE resin and thermoset epoxy resin was investigated by quasi‐static or drop tower stab resistance testing, and the stab resistance behavior against different shapes of impactors was also evaluated. The destruction behavior of LDPE reinforced p‐aramid fabrics against a knife impactor shows three distinctive steps; the initial penetration step with maximum strength, the cutting step by knife edge, and the destruction step of accumulated fiber bundles. On the other hand, epoxy resin reinforced p‐aramid fabrics against a knife impactor exhibit just two steps without the accumulation of fiber bundles. In the case of a spike impactor, the maximum stab resistant strength is observed from the initial penetration step; however, the stab resistant strength after initial penetration drastically decreased regardless of the reinforcing resins. It is also found that, even if the LDPE reinforced fabrics are multilayered, the performance improvement by resin reinforcement is observed only from the initial penetration step and the stab resistant strengths of the cutting step and the fiber accumulation step are not improved. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Novel composite nanofilm of electropolymerization and self‐assembling on AA5052 surface as anticorrosion coating
Authors: Wang Fang , Liu Junjun , Li Yanni , Wang Yabin
Published: September 2011

Electropolymerization nanofilm was prepared by cyclic voltammogram with 6N,N‐diallylamino‐1,3,5‐triazine‐2,4‐dithiol monosodium (DAN) on the AA5052 surface in 0.15M NaNO2 at 10°C, then octyl‐triethoxysilane (OTES) film was fabricated on the poly(6N,N‐diallylamino‐1,3,5‐triazine‐2,4‐dithiol) nanofilm (PDA) covered AA5052 surface by self‐assembling method to obtain the composite polymeric nanofilm (C‐PDA/OTES). The composite polymeric nanofilm was characterized by means of FTIR spectra, scanning electron microscope (SEM), contact angle, and potentiodynamic polarization. The results showed that the C‐PDA/OTES covered surface was more homogenous, compact, hydrophobic compared with PDA covered surface and had excellent protection efficiency. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Improving the thermal and mechanical properties of poly(propylene carbonate) by incorporating functionalized graphite oxide
Authors: Bian J. , Wei X.W. , Gong S. J. , Zhang H. , Guan Z. P.
Published: September 2011

Poly(propylene carbonate) (PPC) is a new biodegradable aliphatic polycarbonate. However, the poor thermal stability, low glass transition temperatures (Tg), and relatively low mechanical property have limited its applications. To improve the thermal and mechanical properties of PPC, functionalized graphite oxide (MGO) was synthesized and mixed with PPC by a solution intercalation method to produce MGO/PPC composites. A uniform structure of MGO/PPC composites was confirmed by X‐ray diffraction and scanning electron microscope. The thermal and mechanical properties of MGO/PPC composites were investigated by thermal gravimetric analysis, differential scanning calorimetric, dynamic mechanical analysis, and electronic tensile tester. Due to the nanometer‐sized dispersion of layered graphite in polymer matrix, MGO/PPC composites exhibit improved thermal and mechanical properties than pure PPC. When the MGO content is 3.0 wt %, the MGO/PPC composites shows the best thermal and mechanical properties. These results indicate that nanocomposition is an efficient and convenient method to improve the properties of PPC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Improvement of the interfacial adhesion between PBO fibers and PPESK matrices using plasma‐induced coating
Authors: Zhang Xiangyi , Chen Ping , Kang Xiaotao , Chen Mingxin , Wang Qian
Published: September 2011

This work deals with the plasma‐induced coating process on the surface of PBO fibers to obtain a strong interfacial adhesion between the poly(p‐phenylene benzobisoxazole) (PBO) fibers and the poly(phthalazinone ether sulfone ketone) (PPESK) matrices. The process consisted of four steps: (a) plasma preactivation of PBO fibers; (b) immersion in an epoxy resin solution; (c) drying and then soaking with the PPESK solution; (d) shaped by compression molding technique. The orthogonal experiments used in this study enable the determination of the significant experimental parameters that influence efficiency of the process by comparing the values of ILSS. The order of their influences was the concentration > power > treating time > treating pressure. The results of the interlaminar shear strength (ILSS) and water absorption showed that the ILSS of the composite increased by 56.5% after coating, meanwhile the water absorption declined to 0.32%. The changes of the surface chemical composition, the surface morphology, and the surface free energy of fibers were studied by FTIR spectroscopy, atomic force microscope (AFM), and dynamic contact angle analysis (DCAA), respectively. Fracture mechanism of the composite was examined by scanning electron microscope (SEM). The results indicated that plasma‐induced coating process was an efficient method to enhance the interfacial adhesion of PBO fibers and PPESK matrices. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Sequential interpenetrating polymer networks of novolac resin and poly(2‐ethyl hexyl acrylate)—thermal, mechanical, and morphological study
Authors: Goswami Sudipta , Maji Sanjoy K.
Published: September 2011

Interpenetrating polymer networks (IPN) of novolac/poly (2‐ ethyl hexyl acrylate) (PEHA) have been prepared via in situ sequential technique of IPN formation. Full and semi‐IPNs were prepared with different blend ratios (w/w) e.g., 90 : 10, 80 : 20, and 70 : 30 in which the major constituent was novolac resin. A gradual decrease in specific gravity and hardness values was observed with increase in PEHA incorporation. A steady decrease in crosslink density with increase in PEHA fraction in the IPNs was quite evident. The IPNs were characterized with respect to their mechanical properties, e.g., ultimate tensile strength, percentage elongation at break, modulus, and toughness. Thermal behavior was studied by differential scanning calorimetry and thermogravimetric analysis. A plasticizing influence of PEHA on the rigid, brittle, and hard matrix of crosslinked phenolic resin is evidenced from the mechanical and thermal properties. The two‐phase surface morphology is revealed by scanning electron microscope. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
The water state in crosslinked poly(vinyl alcohol)–collagen hydrogel and its swelling behavior
Authors: Lin Hai , Dan Weihua , Dan Nianhua
Published: September 2011

Poly vinyl alcohol (PVA) with pendent carboxyl group was synthesized and verified. The collagen was chemical crosslinked with the produced PVA under the help of crosslinker. Then, the PVA–collagen hydrogels were prepared through the repeated freezing–thawing. Since the water states in hydrogels play an important role in the performance of the product, thermogravimetric (TG) analysis and differential scanning calorimeter (DSC) were conducted to study the different states of water. The results indicated that the weight ratio of nonfreezable water to dry gel in PVA–collagen hydrogels was about 25%. Meanwhile, the swelling behaviors in distilled water and 0.9% saline were studied. The one‐phase exponential associate equation can fit the process very well. Calculated from the simulation equation, the swelling ratios at equilibrium in distilled water and saline were 14.353 g/g dry gel and 14.205 g/g dry gel, respectively. The results illustrated that the ions in solution would decrease the swelling ratio of the hydrogel. At the same time, the lyophilization might have slighter influence to the microstructure of hydrogels and should be more suitable for the swelling research than heat drying. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis and Anticancer Activity of 13‐Membered Cyclic Enediynes
Authors: Sharma Mukul , Joshi Mukesh C , Kumar Vineet , Malhotra Sanjay V. , Rawat Diwan S.
Published: September 2011

We herein describe the synthesis of 15 novel 13‐membered cyclic enediyne derivatives using simple and straightforward approach. Representative examples were screened for their anticancer activities on 60 different human tumor cell lines representing various histologies viz. leukemia, melanoma, and cancers of lung, colon, kidney, ovary, breast, prostate, and central nervous system. The enediyne derivatives with halogen substitutions, especially fluorides were found to be active against most of the cell lines. The initial results indicates marginal to good inhibition for the growth of tumor cells for several cell lines, which shows the potential of these class of compound towards anticancer application.
Primary central nervous system vasculitis presenting with intracranial hemorrhage
Authors: Salvarani Carlo , Brown Robert D. , Calamia Kenneth T. , Christianson Teresa J. H. , Huston John , Meschia James F. , Giannini Caterina , Miller Dylan V. , Hunder Gene G.
Published: September 2011

Objective

To describe a subset of cases in a large retrospectively identified cohort of patients with primary central nervous system vasculitis (PCNSV) who present with intracranial hemorrhage.

Methods

The study consisted of a cohort of 131 consecutive patients with PCNSV who were seen at the Mayo Clinic over a 25‐year period from 1983 to 2007. The diagnosis of PCNSV was based on findings of brain or spinal cord biopsy, cerebral angiography, or both. Intracranial hemorrhage at presentation was defined as the presence of intracerebral or subarachnoid hemorrhage on computed tomography or magnetic resonance imaging (MRI) of the brain within 3 months of the date of PCNSV diagnosis. The clinical, laboratory, radiologic, and pathologic findings, therapy, and outcomes in patients presenting with intracranial hemorrhage were compared with those without intracranial hemorrhage.

Results

Sixteen patients (12.2%) had evidence of intracranial hemorrhage at or near the time of diagnosis. Twelve patients had intracerebral hemorrhage, and 4 had subarachnoid hemorrhage. Twelve patients were diagnosed by findings on angiography and 4 by findings on CNS biopsy. Compared with the 115 patients without intracranial hemorrhage, the 16 patients presenting with intracranial hemorrhage were more frequently women, less frequently had altered cognition, a persistent neurologic deficit, or stroke at presentation, less frequently had MRI evidence of cerebral infarctions, and less frequently needed therapy at last followup. A necrotizing histopathologic pattern of vasculitis was observed in 3 of the 4 patients with positive biopsy findings (75%).

Conclusion

Our findings suggest that intracranial hemorrhage may not be an infrequent occurrence in early PCNSV. Necrotizing vasculitis may be a predominant histopathologic pattern.
A putative functional variant within the UBAC2 gene is associated with increased risk of Behçet's disease
Authors: Sawalha Amr H. , Hughes Travis , Nadig Ajay , Yılmaz Vuslat , Aksu Kenan , Keser Gokhan , Cefle Ayse , Yazıcı Ayten , Ergen Andaç , Alarcón‐Riquelme Marta E. , Salvarani Carlo , Casali Bruno , Direskeneli Haner , Saruhan‐Direskeneli Güher
Published: September 2011

Objective

Using a genome‐wide association scan and DNA pooling, we previously identified 5 novel genetic susceptibility loci for Behçet's disease. We undertook this study to establish the genetic effect within the UBAC2 gene, in the course of which we replicated this genetic association and identified a functional variant within this locus.

Methods

We studied a total of 676 Behçet's disease patients and 1,096 controls. The discovery set included 156 patients and 167 controls from Turkey, and the replication sets included 376 patients and 369 controls from Turkey and 144 patients and 560 controls from Italy. Genotyping of 14 single‐nucleotide polymorphisms (SNPs) within and around UBAC2 was performed using TaqMan SNP genotyping assays.

Results

The genetic association between Behçet's disease and UBAC2 was established, replicated, and confirmed (meta‐analysis odds ratio 1.84, P = 1.69 × 10−7). Haplotype analysis identified both a disease‐risk haplotype and a protective haplotype (P = 0.00014 and P = 0.0075, respectively). Using conditional haplotype analysis, we identified the SNP rs7999348 (A/G) within UBAC2 as the most likely SNP with a genetic effect independent of the haplotypic effect formed by the remaining associated SNPs in this locus. Indeed, we demonstrated that rs7999348 tags a functional variant associated with increased messenger RNA expression of a UBAC2 transcript variant in peripheral blood mononuclear cells of individuals homozygous for the Behçet's disease–associated “G” allele. Further, our data suggested the possibility of multiple genetic effects that increase susceptibility to Behçet's disease in the UBAC2 locus.

Conclusion

We established and confirmed the genetic association between UBAC2 and Behçet's disease in 3 independent sets of patients and controls. We identified the minor allele in rs7999348 as a disease‐risk allele that tags altered UBAC2 expression.
Localized expression of tenascin in systemic sclerosis–associated pulmonary fibrosis and its regulation by insulin‐like growth factor binding protein 3
Authors: Brissett Monique , Veraldi Kristen L. , Pilewski Joseph M. , Medsger Thomas A. , Feghali‐Bostwick Carol A.
Published: September 2011

Objective

To determine the role of insulin‐like growth factor binding protein 3 (IGFBP‐3) in mediating the effects of transforming growth factor β (TGFβ) on tenascin‐C (TN‐C) production and to assess the levels of TN‐C in vivo in patients with systemic sclerosis (SSc)–associated pulmonary fibrosis.

Methods

Human primary lung fibroblasts were stimulated with TGFβ or IGFBP‐3 in the presence or absence of specific small interfering RNAs and chemical inhibitors of the signaling cascade. TN‐C levels in lung tissue specimens obtained from patients with SSc‐associated pulmonary fibrosis were assessed using immunohistochemical analysis and were compared with the levels in specimens obtained from normal donors. TN‐C levels were quantified in sera from normal donors and patients with SSc with or without pulmonary fibrosis, using an enzyme‐linked immunosorbent assay.

Results

IGFBP‐3 mediated the induction of TN‐C by TGFβ. Direct induction of TN‐C by IGFBP‐3 occurred in a p38 MAP kinase–dependent manner. TN‐C levels were abundant in lung tissues from patients with SSc and were localized to subepithelial layers of the distal airways. No TN‐C was detectable around the proximal airways. Patients with SSc‐associated pulmonary fibrosis had significantly higher levels of circulating TN‐C compared with SSc patients without pulmonary fibrosis. Longitudinal samples obtained from patients with SSc before and after the onset of pulmonary fibrosis showed increased levels of TN‐C after the onset of pulmonary fibrosis.

Conclusion

IGFBP‐3, which is overexpressed in fibrotic lungs, induces production of TN‐C by subepithelial fibroblasts. The increased lung tissue levels of TN‐C parallel the levels detected in the sera of SSc patients with pulmonary fibrosis, suggesting that TN‐C may be a useful biomarker for SSc‐related pulmonary fibrosis.
Treatment with tumor necrosis factor inhibitors and the risk of acute coronary syndromes in early rheumatoid arthritis
Authors: Ljung Lotta , Simard Julia F. , Jacobsson Lennart , Rantapää‐Dahlqvist Solbritt , Askling Johan ,   Anti‐Rheumatic Therapy in Sweden (ARTIS) Study Group
Published: September 2011

Objective

Rheumatoid arthritis (RA) is associated with an increased risk of ischemic heart disease, in both early and established RA. Data on the risk of ischemic heart disease in relation to therapy with tumor necrosis factor (TNF) antagonists (anti‐TNF) are conflicting in patients with established RA and essentially lacking in those with early RA. In established RA, the risk of myocardial infarction has been linked to the response to anti‐TNF therapies. The aim of this study was to determine the risk of acute coronary syndromes (ACS) in patients with early RA in relation to treatment with, and response to, anti‐TNF.

Methods

A cohort consisting of patients in whom RA was diagnosed between 1999 and 2007 was identified from the Swedish Rheumatology Register (n = 6,000), from which information on disease activity and pharmacologic treatments was extracted. In a cohort study, the risk of first occurrence of an ACS was compared between patients treated with anti‐TNF and those without exposure to anti‐TNF, using hazard ratios (HRs). In a nested case–control study, the relationship between response to anti‐TNF according to the European League Against Rheumatism (EULAR) response criteria and the risk of ACS was investigated.

Results

In the cohort study, treatment with anti‐TNF was not related to any statistically significant alteration in the risk of ACS (HR 0.80, 95% confidence interval [95% CI] 0.52–1.24). In the nested case–control study, a good or moderate EULAR treatment response at 3 months and at 6 months was not associated with a risk of ACS (odds ratio [OR] 1.7, 95% CI 0.5–5.1 and OR 1.5, 95% CI 0.3–6.9, respectively), when adjusted for disease activity before treatment start.

Conclusion

In this study of patients treated with anti‐TNF within the first years of RA, neither treatment with, nor response to, anti‐TNF therapy could be linked to any statistically significant decrease in the risk of ACS.
The relationship of vibratory perception to dynamic joint loading, radiographic severity, and pain in knee osteoarthritis
Authors: Shakoor Najia , Lee Kristin J. , Fogg Louis F. , Wimmer Markus A. , Foucher Kharma C. , Mikolaitis Rachel A. , Block Joel A.
Published: September 2011

Objective

Patients with knee osteoarthritis (OA) have been shown to have somatosensory deficits of the lower extremity. This study was designed to assess the association of these deficits with dynamic joint loading and their relationship to the structural and symptomatic severity of knee OA.

Methods

Subjects with symptomatic knee OA underwent evaluation of the vibratory perception threshold (VPT) using a biothesiometer at 5 sites at the lower extremity. Dynamic joint loading was assessed through gait analyses. Knee pain was evaluated using a visual analog scale score for pain based on the Western Ontario and McMaster Universities OA Index. Radiographic severity of knee OA was assessed using the Kellgren/Lawrence (K/L) grading scale on radiographs obtained with the knee in a standing position.

Results

Dynamic knee joint loading was directly associated with the VPT at the metatarsophalangeal (MTP) joint (Spearman's rho = 0.384, P = 0.033), indicating that the worse the vibratory sense, the higher the knee load during gait. The K/L severity grade was directly associated with the VPT at the MTP joint and lateral femoral condyle, after adjustment for age, sex, body mass index, and knee pain. After adjustment for confounders, there were no significant associations observed between the VPT and pain at any of the sites tested.

Conclusion

These findings demonstrate an association between greater somatosensory deficits and higher dynamic loads in OA. They also demonstrate structural consequences associated with somatosensory deficits in OA, since the extent of sensory loss directly correlated with the radiographic severity of knee OA. However, there was no relationship observed between vibratory sense and symptomatic knee OA pain.
A new approach for Arabic text classification using Arabic field‐association terms
Authors: Atlam El‐Sayed , Morita Kazuhiro , Fuketa Masao , Aoe Jun‐ichi
Published: September 2011

Field‐association (FA) terms give us the knowledge to identify document fields using a limited set of discriminating terms. Although many earlier methods tried to extract automatically relevant FA terms to build a comprehensive dictionary, the problem lies in the lack of an effective method to extract automatically relevant FA terms to build a comprehensive dictionary. Moreover, all previous studies are based on FA terms in English and Japanese, and the extension of FA terms to other languages such as Arabic could benefit future research in the field. We present a new method to build a comprehensive Arabic dictionary using part‐of‐speech, pattern rules, and corpora in Arabic language. Experimental evaluation is carried out for various fields using 251 MB of domain‐specific corpora obtained from Arabic Wikipedia dumps and Alhayah news selected average of 2,825 FA terms (single and compound) per field. From the experimental results, recall and precision are 84% and 79%, respectively. We propose amended text classification methodology based on field association terms. Our approach is compared with Nave Bayes (NB) and kNN classifiers on 5,959 documents from Wikipedia dumps and Alhayah news. The new approach achieved a precision of 80.65% followed by NB (72.79%) and kNN (36.15%).
Z‐DNA Recognition in B‐Z‐B Sequences by a Cationic Zinc Porphyrin
Authors: D'Urso Alessandro , Holmes Andrea E. , Berova Nina , Balaz Milan , Purrello Roberto
Published: September 2011

For the first time it has been shown by spectroscopic studies such as circular dichroism and UV/Vis that cationic zinc porphyrin serves as a selective spectroscopic sensor that is able to recognize short left‐handed Z‐DNA tracts embedded in the B‐Z‐B sequences.
Desorption Dynamics, Internal Energies, and Imaging of Organic Molecules from Surfaces with Laser Desorption and Vacuum Ultraviolet (VUV) Photoionization
Authors: Kostko Oleg , Takahashi Lynelle K. , Ahmed Musahid
Published: September 2011

There is enormous interest in visualizing the chemical composition of organic material that comprises our world. A convenient method to obtain molecular information with high spatial resolution is imaging mass spectrometry. However, the internal energy deposited within molecules upon transfer to the gas phase from a surface can lead to increased fragmentation and to complications in analysis of mass spectra. Here it is shown that in laser desorption with postionization by tunable vacuum ultraviolet (VUV) radiation, the internal energy gained during laser desorption leads to minimal fragmentation of DNA bases. The internal temperature of laser‐desorbed triacontane molecules approaches 670 K, whereas the internal temperature of thymine is 800 K. A synchrotron‐based VUV postionization technique for determining translational temperatures reveals that biomolecules have translational temperatures in the range of 216–346 K. The observed low translational temperatures as well as their decrease with increased desorption laser power is explained by collisional cooling. An example of imaging mass spectrometry on an organic polymer by using laser‐desorption VUV postionization shows 5 μm feature details while using a 30 μm laser spot size and 7 ns pulse duration. Applications of laser‐desorption postionization to the analysis of cellulose, lignin, and humic acids are briefly discussed.
Synthesis and Applications of Tricarbonyliron Complexes of Dendralenes
Authors: Toombs‐Ruane Henry , Osinski Nik , Fallon Thomas , Wills Cindy , Willis Anthony C. , Paddon‐Row Michael N. , Sherburn Michael S.
Published: September 2011

[3]Dendralene and [4]dendralene are converted smoothly into tricarbonyliron complexes. The structures of four complexes analyzed by DFT and single‐crystal X‐ray analysis show that, in contrast to free hydrocarbons, complexed dendralenes prefer a roughly in‐plane conformation. The complexes are stable towards Fe(CO)3 group migration up to 150 °C. The synthetic value of Fe(CO)3 complexation in the dendralene series is demonstrated through a variety of selective synthetic manipulations (Diels–Alder reaction, dipolar cycloaddition, Simmons–Smith cyclopropanation, dihydroxylation, olefin cross metathesis) that are not achievable by direct transformation of the free hydrocarbons. Application to the synthesis of a previously unreported, highly reactive linear/cross‐conjugated hydrocarbon is also described.