bluuebunny/crossref_metadata_2025_split huggingface dataset:
In situ preparation, electrospinning, and characterization of polyacrylonitrile nanofibers containing silver nanoparticles
Authors: Sichani G.Naddaf , Morshed M. , Amirnasr M. , Abedi D. 
Published: December 2009

AbstractSilver nanoparticles were prepared from a polyacrylonitrile (PAN)/N,N‐dimethylformamide solution of silver nitrate (0.05–0.5 wt %) with light treatment (xenon arc) to reduce Ag+ ions into Ag0. The formation of silver nanoparticles in the PAN solution and the effect of treatment time on the numbers of silver nanoparticles, their average diameter and size distribution were investigated by UV–visible spectroscopy. In addition, the average size of silver nanoparticles and their shapes in colloidal solution were determined by transmission electron microscopy images and found to be on the order of 10 nm. The resulting solution was electrospun into PAN nanofibers. An increase in the salt concentration led to decreases in the nanofiber diameter and bead numbers (determined by scanning electron microscopy images) and an increase in the crystallinity (confirmed by X‐ray diffraction patterns). A continuous rate of silver release from the nanofiber web was monitored by the atomic absorption technique. These nanofibers showed strong antibacterial activity against Pseudomonas aeruginosa. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Open porous emulsion‐templated monoliths: Effect of the emulsion preparation conditions on the foam microstructure and properties
Authors: Abbasian Z. , Moghbeli M. R. 
Published: December 2009

AbstractHighly open porous polymer foams were prepared via the polymerization of 10 : 1 styrene/divinylbenzene high‐internal‐phase emulsions (HIPEs) prepared under various emulsifying conditions. The effects of the emulsification stirring speed (SS) and rate of aqueous droplet‐phase addition on the HIPE equilibrium torque value, an approximate characterization of HIPE viscosity, and the microstructure and properties of the resulting HIPE polymer solid foams were investigated. SS was varied over the range 400–1200 rpm for aqueous‐droplet‐phase addition rates (AARs) of 0.53 and 1.3 mL/min. The microscopic results showed that at lower AARs, increasing SS decreased the weighted‐average cell diameter from 24.31 to 13.55 μm, whereas the cell size distribution was broadened, and the intercellular pore size varied irregularly in the range 0.76–1.42 μm. The average cell diameter and intercellular pore size for the solid foams prepared at higher AARs were greater than that of those prepared at lower AARs. The density of the foam materials ranged from 0.057 to 0.072 g/cm3, whereas their thermal conductivity varied from 0.649 to 0.705 W m−1 °C−1. The highest compressive stress–strain properties were found for the foam sample prepared with highest SS and a lower AAR. Adding electrolyte CaCl2 to HIPE produced remarkable increases in the void diameter and intercellular pore size, especially at lower SS values. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of the coagulation‐bath temperature on the phase‐separation process of poly(vinylidene fluoride)‐graft‐poly(N‐isopropylacrylamide) solutions and membrane structures
Authors: Guo Yanfen , Feng Xia , Chen Li , Zhao Yiping , Bai Jingna 
Published: December 2009

AbstractA poly(vinylidene fluoride)‐graft‐poly(N‐isopropylacrylamide) (PVDF‐g‐PNIPAAm) copolymer was synthesized, and flat‐sheet membranes were prepared via the phase‐inversion method with N,N‐dimethylformamide (DMF) as the solvent and water as the coagulation bath. The effects of the coagulation‐bath temperature on poly(vinylidene fluoride) (PVDF)/DMF/water and PVDF‐g‐PNIPAAm/DMF/water ternary systems were studied with phase diagrams. The results showed that the phase‐separation process could be due to the hydrophilicity/hydrophobicity of poly(N‐isopropylacrylamide) at low temperatures, and the phase‐separation process was attributed to crystallization at high temperatures. The structures and properties of the membranes prepared at different coagulation‐bath temperatures were researched with scanning electron microscopy, porosity measurements, and flux measurements of pure water. The PVDF‐g‐PNIPAAm membranes, prepared at different temperatures, formed fingerlike pores and showed higher water flux and porosity than PVDF membranes. In particular, a membrane prepared at 30°C had the largest fingerlike pores and greatest porosity. The water flux of a membrane prepared in a 25°C coagulation bath showed a sharp increase with the temperature increasing to about 30°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The effects of the pH value of the swelling medium on the kinetics of the swelling of a poly(acrylic acid) hydrogel
Authors: Jovanovic Jelena , Adnadjevic Borivoj , Kostic Aleksandar 
Published: December 2009

AbstractThe isothermal kinetics curves of the swelling of a poly(acrylic acid) hydrogel in buffer solutions of different pH values (5, 7, and 9) at temperatures ranging from 30 to 40°C were determined. The possibilities of applying the Fick kinetics model and the Peppas equation were examined. It was found that the applicability of these models were limited. The kinetics model of a first‐order chemical reaction was found to describe the swelling kinetics of the PAA hydrogel in all the investigated buffer solution at all the investigated temperatures. Swelling kinetics is determined by the rate of expansion of the network. The kinetic parameters (Ea, ln A) of the swelling of the PAA hydrogel in buffer solutions of different pH values were determined. The activation energy and the pre‐exponential factor of the swelling of the PAA hydrogel in buffer medium decreased with increasing pH value of the swelling medium. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of poly(ester‐ether‐imide)s derived from 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene
Authors: Behniafar Hossein , Ghorbani Mostafa 
Published: December 2009

AbstractA series of novel aromatic poly(ester‐ether‐imide)s with inherent viscosity values of 0.44–0.74 dL g−1 were prepared by the diphenylchlorophosphate‐activated direct polycondensation of an imide ring‐containing diacid namely 5‐(4‐trimellitimidophenoxy)‐1‐trimellitimido naphthalene (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. Owing to comparison of the characterization data, an ester‐containing model compound (2) was also synthesized by the reaction of 1 with phenol. The model compound 2 and the resulted polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λmax values of the poly(ester‐ether‐imide)s were also determined. The resulting polymers exhibited an excellent organosolubility in a variety of high polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, and N‐methyl‐2‐pyrrolidone. They were soluble even in common less polar organic solvents such as pyridine, m‐cresol, and tetrahydrofuran on heating. Crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resulted polymers exhibited nearly an amorphous nature. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 221 and 245°C. Thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(ester‐ether‐imide)s were found to be over 410°C in nitrogen. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hydride addition of methylhydridesiloxanes to conjugated cyclohexa‐1,3‐diene
Authors: Mukbaniani O. , Tatrishvili T. , Koberidze Kh. , Scherf U. 
Published: December 2009

AbstractThe reaction of hydride polyaddition of methylhydridesiloxanes to conjugated cyclohexa‐1,3‐diene, in the presence of catalytic amount of platinum hydrochloric acid, has been investigated at several temperatures. The polyorganosiloxanes with cyclohexenyl fragments in the side chain, completely soluble in organic solvents, were synthesized. The hydride polyaddition reaction order, activation energies, and rate constants were found. By quantum‐chemical half‐empirical method AM1, the electronic characteristics of cyclohexa‐1,3‐diene: the charges on the carbon atoms and bonds orders were calculated. For full characterization of hydrosilylation reaction, calculations for modeling reaction between methyldimethoxysilane and cyclohexa‐1,3‐diene were carried out using Gaussian 03 program package. The geometries of reactants, transition states, and products were optimized using PM3 semiempirical method followed by single‐point calculations at B3LYP/6‐31G(d) level of density functional theory. It was concluded that the course of hydride addition of modeling reaction of methyldimethoxysilane to cyclohexa‐1,3‐diene energetically is more favorable by 1,4‐addition. The synthesized oligomers were characterized by FTIR, 1H‐ and 13C‐NMR spectroscopy, thermogravimetry, gel permeation chromatography, differential scanning calorimetry, and wide‐angle X‐ray diffractometry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
The synthesis of water soluble cationic microgels by dispersion polymerization: Their performance in kaolin deposition onto fiber
Authors: Ondaral Sedat , Usta Mustafa , Gumusderelioglu Menemse , Arsu Nergis , Balta Demet Karaca 
Published: December 2009

AbstractThe water soluble cationic microgels (CMG), intramolecularly cross‐linked cationic polymers of acrylamide (Am) and diallyldimethylammonium chloride (DADMAC), were synthesized with dispersion polymerization in the mixture of tert‐butanol (TBA)/water in the presence N,N′‐methylene‐bisacrylamide (MBA) as the cross‐linker, poly(N‐vinylpyrrolidone (PVP) as the stabilizer and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. The effects of monomer, cross‐linker, initiator, and stabilizer concentration on both particle size and molecular weight of CMG were investigated. The well dispersed polymer particles were produced in the range of poly dispersity index 1.1–1.4 and the molecular weight distribution with bimodal. Additionally, the efficiencies of two CMGs in the clay deposition on the bleached kraft fibers were investigated and compared with commercially widely used cationic polyacrylamide (CPAM) and poly‐diallyldimethylammonium chloride (poly‐DADMAC). The experiments showed that the CMGs were found as the effective flocculation agents and their efficiencies depended on their molecular weight and charge density. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effective method for dispersing SiO2 nanoparticles into polyethylene
Authors: Pöllänen Maija , Pelz Uwe , Suvanto Mika , Pakkanen Tuula T. 
Published: December 2009

AbstractAn effective solution mixing method starting from a synthesis solution of SiO2 nanoparticles was developed for dispersing nanoparticles into high‐density polyethylene (HDPE). Spherical SiO2 nanoparticles with narrow size distribution (50–100 nm) were prepared by Stöber method, and solvents of the synthesis solution (EtOH/NH4OH) were gradually replaced with toluene by evaporation under reduced pressure. The SiO2 nanodispersion, in toluene and residual ethanol, was mixed and refluxed with dissolved maleic anhydride grafted polyethylene (PEgMA) at a relatively high SiO2 content (17.8 wt %). The PEgMA‐SiO2 masterbatch was filtered, dried under vacuum, and mixed with HDPE by melt compounding. SiO2 contents in the final HDPE nanocomposites were 3 and 5 wt %. SEM images of the masterbatch and final composites showed the SiO2 nanoparticles to be well dispersed in HDPE. No agglomerates were observed. FTIR results suggest that the interactions between the maleic anhydride group of PEgMA and hydroxyl groups of SiO2 surface involve ester and/or hydrogen bonding. Addition of SiO2 particles and PEgMA to HDPE slightly increased Young's modulus, tensile strength, breaking strength, and elongation at break, indicating enhanced toughness of the nanocomposites. The measured Young's moduli of HDPE‐PEgMA‐SiO2 composites agreed well with Young's moduli predicted by Mori‐Tanaka composite theory. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing tetraoxyethylene units exhibiting amphotropic liquid‐crystalline and photoluminescence properties
Authors: Bhowmik Pradip K. , Han Haesook , Nedeltchev Alexi K. , Mandal Hari D. , Jimenez‐Hernandez Jose A. , Mcgannon Patrick M. 
Published: December 2009

AbstractSeveral poly(pyridinium salt)s containing various organic counterions and tetraoxyethylene units in their backbones were synthesized by either ring‐transmutation polymerization reaction of 4,4'‐(1,4‐phenylene)bis(2,6‐diphenylpyrylium tosylate) with bis(2‐(2‐(4‐aminophenoxy)ethoxy)ethyl) ether on heating in dimethyl sulfoxide or metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1H‐NMR and 13C‐NMR spectroscopy, and elemental analyses. Their number‐average molecular weights and polydispersity indices were in the range of 34,000–52,000 and 1.14–1.38, respectively, as determined by gel permeation chromatography. They were characterized both for their thermotropic and lyotropic liquid‐crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. As these polymers exhibited liquid‐crystalline phase both in the melt and in solutions, they are classified as an amphotropic class of ionic polymers. Their light‐emitting properties in a large number of organic solvents that ranged from nonpolar to polar solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
G protein‐coupled receptors: the inside story
Authors: Jalink Kees , Moolenaar Wouter H. 
Published: December 2009

AbstractRecent findings necessitate revision of the traditional view of G protein‐coupled receptor (GPCR) signaling and expand the diversity of mechanisms by which receptor signaling influences cell behavior in general. GPCRs elicit signals at the plasma membrane and are then rapidly removed from the cell surface by endocytosis. Internalization of GPCRs has long been thought to serve as a mechanism to terminate the production of second messengers such as cAMP. However, recent studies show that internalized GPCRs can continue to either stimulate or inhibit cAMP production in a sustained manner. They do so by remaining associated with their cognate G protein subunit and adenylyl cyclase at endosomal compartments. Once internalized, the GPCRs produce cellular responses distinct from those elicited at the cell surface.
Enantiomeric separation of 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs by HPLC with hydroxypropyl‐β‐cyclodextrin as chiral mobile phase additive
Authors: Ye Jincui , Yu Wenying , Chen Guosheng , Shen Zhengrong , Zeng Su 
Published: December 2009

AbstractThe enantio‐separations of eight 2‐arylpropionic acid nonsteroidal anti‐inflammatory drugs (2‐APA NSAIDs) were established using reversed‐phase high‐performance liquid chromatography with hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) as chiral mobile phase additive for studying the stereoselective skin permeation of suprofen, ketoprofen, naproxen, indoprofen, fenoprofen, furbiprofen, ibuprofen and carprofen. The effects of the mobile phase composition, concentration of HP‐β‐CD and column temperature on retention and enantioselective separation were investigated. With 2‐APA NSAIDs as acidic analytes, the retention times and resolutions of the enantiomers were strongly related to the pH of the mobile phase. In addition, both the concentration of HP‐β‐CD and temperature had a great effect on retention time, but only a slight or almost no effect on resolutions of the analytes. Enantioseparations were achieved on a Shimpack CLC‐ODS (150 × 4.6 mm i.d., 5 μm) column. The mobile phase was a mixture of methanol and phosphate buffer (pH 4.0–5.5, 20 mM) containing 25 mM HP‐β‐CD. This method was flexible, simple and economically advantageous over the use of chiral stationary phase, and was successfully applied to the enantioselective determination of the racemic 2‐APA NSAIDs in an enantioselective skin permeation study. Copyright © 2009 John Wiley & Sons, Ltd.
Fragmentation study of iridoid glycosides and phenylpropanoid glycosides in Radix Scrophulariae by rapid resolution liquid chromatography with diode‐array detection and electrospray ionization time‐of‐flight mass spectrometry
Authors: Wu Qian , Yuan Quan , Liu E‐Hu , Qi Lian‐Wen , Bi Zhi‐Ming , Li Ping 
Published: December 2009

AbstractRapid resolution liquid chromatography (RRLC) coupled with diode array detection (DAD) and electrospray ionization time‐of‐flight mass spectrometry (ESI‐TOF MS) method was applied to the mass spectral study of a series of naturally occurring iridoid glycosides and phenylpropanoid glycosides in Radix Scrophulariae, which provides higher speed and increased sensitivity without loss of resolution. With dynamic adjustment as the key role of the fragmentor voltage and confirmed with authentic standards, valuable structural information regarding the nature of both the glycoside skeletons was thus obtained. Most compositions were found to possess organic acid moiety such as cinnamoyl, caffeoyl and ferulyol. Besides extensive fragmentation of the carbohydrate moiety, losses of the hydroxyl and glucose residue units showed in the spectra, permitting the exploration of the skeleton and the identity of substituents in the molecule. Ten major iridoid glycosides and 10 phenylpropanoid glycosides were identified or tentatively characterized based on their retention times, UV and TOF MS data. The major fragmentation pathways of PGs in Radix Scrophulariae obtained through the MS data was schemed systematically for the first time, which provides a reference for other PGs derivatives. Copyright © 2009 John Wiley & Sons, Ltd.
A sensitive and specific HPGPC‐FD method for the study of pharmacokinetics and tissue distribution of Radix Ophiopogonis polysaccharide in rats
Authors: Lin Xiao , Wang Zhuojun , Sun Guilan , Shen Lan , Xu Desheng , Feng Yi 
Published: December 2009

AbstractInterest in antimyocardial ischemic activity of a graminan‐type fructan with a weight average molecular weight of 4.8 kDa extracted from Radix Ophiopogonis (ROP) has necessitated the study of its pharmacokinetics and tissue distribution. For that, a simple HPGPC–FD method was developed for the sensitive and specific determination of FITC‐ROP (fluorescein–isothiocyanate‐labeled ROP) in plasma and rat tissues (heart, liver, spleen, lung, kidney, brain and stomach). The analyte was separated on a Shodex Sugar KS‐802 high‐performance gel column with 0.1 M phosphate buffer (pH 7.0) as mobile phase at a flow rate of 0.5 mL/min, and fluorescence detection at λex 495 nm and λem 515 nm. The calibration curve for FITC‐ROP was linear over the range 0.25–20.0 or 50.0 μg/mL in all studied biosamples with correlation coefficients >0.995. The inter‐day and intra‐day precisions of analysis were not more than 10%, and assay accuracy ranged from 93 to 105% for plasma and from 89 to 108% for tissue homogenates. This method has been confirmed here to be suitable for the study of pharmacokinetics and tissue distribution of ROP and the achieved results are highly instructive for the further pharmaceutical development of ROP, suggesting the promising application of the method to the increasingly important carbohydrate‐based drugs. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and Biophysical Studies of Bis‐Macrocyclic Cobalt/Copper(II) Complexes Having a Pyridine Spacer with CT DNA and 5′‐GMP
Authors: Arjmand Farukh , Aziz Mubashira 
Published: December 2009

AbstractNew bis‐macrocyclic complexes of CoIII, 1, NiII, 2, and CuII, 3, containing pyridyl bridges between 13‐membered macrocyclic subunits, have been synthesized via an in situ one‐pot template condensation reaction (IOPTCR). The proposed structures of these new dinuclear complexes are consistent with the data obtained from elemental analysis, molar conductance, IR, EPR, UV/VIS, 1H‐ and 13C‐NMR, and ESI‐MS. The complexes 2 and 3 possess square‐planar geometry with four secondary N‐atoms coordinated to the metal ion, while complex 1 reveals octahedral geometry in solution due to coordinated H2O molecules. DNA‐Binding properties of the complexes 1 and 3 were investigated by absorption and emission titrations, cyclic voltammetry, and viscosity measurements. Complexes 1 and 3 are strong DNA binders with binding constants, Kb, of 1.64×105 and 2.05×105 M−1, respectively. Hyperchromism, decrease in emission intensity of DNA‐bound ethidium bromide (EB), and changes observed in the viscosity and cyclic voltammograms in the presence of added metal complexes reveals that the complexes bind to DNA predominantly by electrostatic attraction, substantiated by absorption titration with 5′‐GMP.
Chemical Variability of the Needle Oil of Juniperus communis ssp. alpina from Corsica
Authors: Ottavioli Josephine , Gonny Marcelle , Casanova Joseph , Bighelli Ange 
Published: December 2009

AbstractThe composition of 109 samples of essential oil isolated from the needles of Juniperus communis ssp. alpina growing wild in Corsica was investigated by GC (in combination with retention indices), GC/MS, and 13C‐NMR. Forty‐four compounds accounting for 86.7–96.7% of the oil were identified. The oils consisted mainly of monoterpene hydrocarbons, in particular, limonene (9.2–53.9%), β‐phellandrene (3.7–25.2%), α‐pinene (1.4–33.7%), and sabinene (0.1–33.6%). The 109 oil compositions were submitted to k‐means partitioning and principal component analysis, which allowed the distinction of two groups within the oil samples. The composition of the major group (92% of the samples) was dominated by limonene and β‐phellandrene, while the second group contained mainly sabinene beside limonene and β‐phellandrene.
The Essential Oil of Bupleurum fruticosum L. from Corsica: A Comprehensive Study
Authors: Liu Kai , Lota Marie Laure , Casanova Joseph , Tomi Félix 
Published: December 2009

AbstractA detailed analysis of Bupleurum fruticosum oil was carried out by combination of GC (RI), GC/MS, and 13C‐NMR analyses. After fractionation by column chromatography, 34 components accounting for 97.8% of the oils were identified. The main component was β‐phellandrene (67.7%), followed by sabinene (9.3%), and limonene (5.6%). The evolution of the chemical composition according to the stages of development of the plant was investigated as well as the composition of leaf, twig, and flower oils. A solvent‐free microwave extraction (SFME) of aerial parts was carried out and the composition of the extract compared with that of the essential oil. Finally, 57 oil samples isolated from aerial parts of individual plants, collected all around Corsica, were analyzed, and the data were submitted to statistical analysis. Although the contents of the main components varied, only one group emerged, accompanied with some atypical compositions.
Chemical Diversity in Himalayan Elsholtzia Species
Authors: Mathela Chandra S. , Padalia Rajendra C. , Joshi Subhash C. , Singh Krishna K. , Bisht Dinesh S. , Pant Anil K. , Kharkwal Harendra 
Published: December 2009

AbstractThe terpenoid composition of essential oils from the leaves of five Elsholtzia species, viz., E. eriostachya Benth., E. cristata Willd., E. polystachya Benth., E. flava Benth., and E. pilosa Benth., collected from the Himalayan region (India), was examined by GC, GC/MS, and NMR analyses. Comparison of the results with previous reports revealed new chemotypes. Cluster analysis was carried out in order to discern the similarities and differences within the essential‐oil compositions at their subspecies/chemotype level. Based on the major constituents of the essential oils, six chemical groups were obtained.