bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic Field‐Effect Transistors and Unipolar Logic Gates on Charged Electrets from Spin‐On Organosilsesquioxane Resins
Authors: Huang C. , West J. E. , Katz H. E.
Published: December 2006

Controllable shifting of threshold voltage and modulation of current in organic field‐effect transistors (OFETs) is demonstrated, resulting in the formation of unipolar inverters by making use of space‐charge electrets. Prior to the deposition of the organic semiconductor (OSC), negative corona charges are injected and trapped in the bulk of the organosilsesquioxane glass resin gate dielectrics. The effective surface potential is controlled by the corona‐charging and subsequent annealing process. It is found that the shift of the transfer characteristics is governed by the electrostatic induction effects of the charged gate electrets, and this observed shift can be related to the surface potential of the layer next to the transistor channel. The process control, efficiency, and long‐term stability of charge storage in spin‐on organosilsesquioxane glass resins are sufficient to enable the construction of simple unipolar inverters and to allow for circuit tuning. New OFET unipolar inverters with an enhancement‐mode driver and a depletion‐mode load are presented, composed of only two simple OFETs with the same channel dimensions and the same p‐type OSC on charged electrets. This design allows the implementation of full‐swing organic logic circuits and illustrates a potential process simplification for organic electronics.
Hemangiomas: Their uses and abuses
Authors: Cohen Jr M. Michael
Published: December 2006

Hemangiomas are vascular tumors, and are distinct from vascular malformations. The term “hemangioma” is frequently misapplied by various medical specialists. This article briefly summarizes the main types of hemangiomas: infantile, rapidly involuting, and noninvoluting types. More complex conditions are also reviewed, such as hemangiomas of the liver and PHACES. The discussion then focuses on common vascular misnomers and proper descriptive terminology for hemangiomas: solitary (small, large, or diffuse) and multifocal. It is concluded that the term “segmental hemangioma” is imprecise, ill‐advised, misguided, and should be abandoned. © 2006 Wiley‐Liss, Inc.
Molekulare Erkennung von Phosphaten in der Strukturbiologie
Authors: Hirsch Anna K. H. , Fischer Felix R. , Diederich François
Published: December 2006

Die medizinisch‐chemische Forschung hat sich in den letzten Jahren Proteinen zugewandt, die wie Proteinkinasen und Proteinphosphatasen eine Phosphatbindungsstelle aufweisen. Dieser Aufsatz versucht, mithilfe von Datenbankrecherchen einen Überblick über die wichtigsten Prinzipien der molekularen Erkennung von Phosphatgruppen durch Enzyme zu geben. 3003 Kristallstrukturen von Proteinen mit gebundenem organischem Phosphat aus der RCSB‐Proteindatenbank wurden im Hinblick auf H‐Brücken zwischen Protein und Ligand untersucht. Die bekannten Bindungsmotive für Phosphate werden behandelt und Ähnlichkeiten bei der Komplexierung von Phosphaten durch synthetische Rezeptoren hervorgehoben. Eine Analyse der Häufigkeit, mit der spezifische Aminosäuren in unterschiedlichen phosphatbindenden Enzymklassen H‐Brücken eingehen, führt zu einer für die Enzymklasse charakteristischen Verteilung. Der Aufsatz zeigt, dass bei strukturbasierter Ligandenentwicklung und ‐optimierung die Umgebung der Phosphatbindungsstelle sorgfältig mitberücksichtigt werden sollte und weist gleichzeitig auf Alternativen hin, wie diese Bindungstaschen zu füllen sind.
Titelbild: Inclusion of Cavitands and Calix[4]arenes into a Metallobridged para‐(1H‐Imidazo[4,5‐f][3,8]phenanthrolin‐2‐yl)‐Expanded Calix[4]arene (Angew. Chem. 1‐2/2007)
Authors: Botana Enrique , Da Silva Eric , Benet‐Buchholz Jordi , Ballester Pablo , de Mendoza Javier
Published: December 2006

Fressen und gefressen werden ist ein Prinzip, das nicht nur in der Natur, sondern auch in dem Wirt‐Gast‐System zu finden ist, das J. de Mendoza et al. in der Zuschrift auf S. 202 ff. beschreiben und in dem ein Wirt (kleinere Calix[4]arene und Cavitanden) selbst zur “Beute” eines noch größeren Wirtes wird (eines Metallocavitanden aus einem Calix[4]aren mit durch Re‐Atome verbundenen [3,8]Phenanthrolin‐Untereinheiten). Das Titelbild zeigt die Komplexierung eines Cavitanden (von P. Ballester) vor einer Unterwasseraufnahme am Cap Andritxol auf Mallorca (von E. Botana).
Syntheses, crystal structures and blue emission of three zinc(II) coordination polymers with a 4,4′‐dicarboxybiphenyl sulfone ligand
Authors: Zhuang Wen‐Juan , Jin Lin‐Pei
Published: December 2006

Three novel zinc complexes [Zn(dbsf)(H2O)2] (1), [Zn(dbsf)(2,2′‐bpy)(H2O)]·(i‐C3H7OH) (2) and [Zn(dbsf)(DMF)] (3) (H2dbsf = 4,4′‐dicarboxybiphenyl sulfone, 2,2′‐bpy = 2,2′‐bipyridine, i‐C3H7OH = iso‐propanol, DMF = N,N‐dimethylformamide) were first obtained and characterized by single crystal X‐ray crystallography. Although the results show that all the complexes 1–3 have one‐dimensional chains formed via coordination bonds, unique three‐dimensional supramolecular structures are formed due to different coordination modes and configuration of the dbsf2− ligand, hydrogen bonds and π–π interactions. Iso‐propanol molecules are in open channels of 2 while larger empty channels are formed in 3. As compared with emission band of the free H2dbsf ligand, emission peaks of the complexes 1–3 are red‐shifted, and they show blue emission, which originates from enlarging conjugation upon coordination. Copyright © 2006 John Wiley & Sons, Ltd.
Research on synthesis and conductivity of ferrocenyl Schiff base and its salt
Authors: Liu Wei‐Jun , Xiong Guo‐Xuan , Wang Wei‐Ping
Published: December 2006

Ferrocenyl Schiff base was synthesized through the condensation of ferrocenecarboxaldehyde and p‐phenylenediamine under neutral conditions, and then a new interesting category of organometallic charge transfer complex was obtained by the doping of ferrocenyl Schiff base with Fe3+, Al3+ and Ti3+ salts. The effects of the dosage of doping agent and doping temperature on the room‐temperature electric conductivity of samples were discussed; in addition, the temperature dependence of the electric conductivity of samples was studied, their structures and compositions were characterized by 1H‐NMR spectra, infrared spectra, ultraviolet spectra and an electron probe X‐ray microanalyser. The results showed that the electric conductivity of sample can increase 4–5 orders of magnitude after doping with a metallic salt, and the electric conductivity has a positive temperature coefficient effect. The electrical activation energies of the complexes in the range 0.09–1.54 eV were calculated from Arrhenius plots, indicating their favourable semiconducting behaviour. Copyright © 2006 John Wiley & Sons, Ltd.
Bioaccumulation of metals and induction of metallo‐ thioneins in selected tissues of common carp (Cyprinus carpio L.) co‐exposed to cadmium, mercury and lead
Authors: Huang Zhi‐Yong , Zhang Qiang , Chen Jing , Zhuang Zhi‐Xia , Wang Xiao‐Ru
Published: December 2006

The concentrations of mercury (Hg), cadmium (Cd) and lead (Pb) at various exposure periods were determined in the gill, kidney, liver and muscle of common carp (Cyprinus carpio L.) co‐exposed to 1.0 µg ml−1 each of Cd2+, Hg2+ and Pb2+ for up to 10 days. Metallothionein fractions (MTs) in these organs were characterized using the hyphenated technique of size‐exclusion chromatography (SEC) and inductively coupled plasma mass spectrometry (ICP‐MS). After 10 days of exposure, maximum toxic metal concentrations of Hg, Cd and Pb were 10.7 (gill), 0.145 (kidney) and 0.112 µg g−1dryweight (gill), respectively. The pattern of accumulation of Hg and Pb was in the order gill > kidney > liver > muscle. In the case of Cd, accumulation was in the order kidney > gill > liver > muscle. Cd and Hg binding MTs were significantly induced in the gill, kidney and liver of all the exposure groups in comparison with the control group (p < 0.05), and the amounts of them increased with the longer exposure time. Despite the higher intracellular Hg concentration and the stronger HgSH binding affinity, the amount of Cd‐binding MTs was much higher than that of Hg‐binding MTs. The results indicate that MT synthesis in these organs was clearly metal‐specific. MTs in gill may be used as a bio‐marker to detect the metal pollution caused by Hg and Cd. Zinc and copper binding MTs in the organs of the exposed fish were also increased. This may be due to the MTs' important role in the homeostatic regulation of essential metals and their protective role against the acute toxicity of non‐essential metals. Even though there was considerable accumulation of lead in the organs of the exposed fish, Pb‐binding MT synthesis was non‐significant. Copyright © 2006 John Wiley & Sons, Ltd.
The determination of methylmercury in biological samples by HPLC coupled to ICP‐MS detection
Authors: Vidler Daniel S. , Jenkins Richard O. , Hall John F. , Harrington Chris F.
Published: December 2006

The use of high‐performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP‐MS) for the determination of methylmercury (MeHg+) in fish tissue and hair samples is described. Analysis of these sample types is required when carrying out biomonitoring studies to determine human dietary exposure to this toxic mercurial compound. The developed method used a mobile phase containing an organic modifier and a sulfydryl compound (1:1 v/v methanol:water containing 0.01% v/v 2‐mercaptoethanol) to limit peak tailing and aid separation. The chromatographic separation was coupled to the ICP‐MS detector via a short piece of PEEK tubing, attached to the nebulizer. A cooled spraychamber and oxygen addition post‐nebulization were required to limit the solvent loading on the plasma and reduce carbon build‐up on the cones, respectively. The sample preparation procedure employed a drying step followed by digestion of the sample using tetramethylammonium hydroxide (TMAH) and heating in an open vessel microwave system. Two fish tissue certified reference materials (CRM), tuna fish CRM 463 and 464 (BCR, Brussels), a tuna fish proficiency test sample, IMEP‐20 (IRMM, Geel, Belgium) and a hair CRM NIES no. 13 (National Institute of Environmental Science, Japan), were used to evaluate the method. The recovery of MeHg+ for these four materials was between 83 and 100%, with precisions better than 6% for three separate extractions of the different materials. The limit of quantitation for MeHg+ using the developed protocol was 0.5 µg Hg g−1. The stability of MeHg+ in the fish sample extracts was also assessed and losses of 14–16% were observed after storage of the extracts in a refrigerator at 5 °C, in high‐density polypropylene tubes, for 6 months. The developed protocol has been used previously with atmospheric pressure ionization mass spectrometry (API‐MS) to provide structural characterization and also with calibration via isotope dilution (IDMS) to provide high accuracy quantitation. Copyright © 2006 John Wiley & Sons, Ltd.
Chemical synthesis, characterization, and direct‐current conductivity studies of polypyrrole/γ‐Fe2O3 composites
Authors: Murugendrappa M. V. , Prasad M. V. N. Ambika
Published: December 2006

The in situ polymerization of pyrrole was carried out in the presence of γ‐Fe2O3 to synthesize polypyrrole/γ‐Fe2O3 composites by a chemical oxidation method. The polypyrrole/γ‐Fe2O3 composites were synthesized with various compositions, including 10, 20, 30, 40, and 50 wt % γ‐Fe2O3 in pyrrole. The polypyrrole/γ‐Fe2O3 composites were characterized with X‐ray diffractometry and infrared spectroscopy. The surface morphology of these composites was studied with scanning electron microscopy. The direct‐current conductivity was studied from 40 to 200°C. The dimensions of the γ‐Fe2O3 particles in the matrix had a greater influence on the conductivity values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2797–2801, 2007
Synthesis of cationic flocculants by the inverse microemulsion copolymerization of acrylamide with 60% 2‐acryloxyethyltrimethyl ammonium chloride in the monomer feed. I. Initiation by ammonium persulfate/sodium disulfite redox system
Authors: Escudero Sanz F. J. , Ochoa Gómez J. R. , Sasia P. M. , de Apodaca E. Díaz , Río P.
Published: December 2006

Acrylamide/2‐acryloxyethyltrimethyl ammon‐ium chloride copolymers in inverse microemulsion, with a cationic charge density of 60% and a concentration of active matter of 30 wt %, of interest as flocculants have been obtained by inverse microemulsion copolymerization. Interesting inverse microemulsion formulations from both industrial and economical standpoints were selected from pseudoternary phase diagrams. These formulations were polymerized by semicontinuous free radical copolymerization in inverse microemulsion using sodium disulfite and ammonium persulfate as initiators. Influence of initiators and initiator addition conditions (specific flow rate and concentration) on semicontinuous polymerization and final product properties as flocculants have been studied. A strong difference in copolymer solution viscosity has been found when an aqueous solution of sodium disulfite is used as initiator instead of sodium disulfite/ammonium persulfate couple redox, specially for low sodium disulfite solution feeding flow. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2826–2836, 2007
Condensation reactions of phenolic resins. VI. Dependence of the molecular association of 2,4,6‐trihydroxymethylphenol on the concentration in an aqueous alkaline medium
Authors: Kamo Naruyuki , Kondo Tetsuo , Morita Mitsuhiro
Published: December 2006

The concentration dependence of the molecular association of 2,4,6‐trihydroxymethylphenol (THMP) as a model compound for phenol–formaldehyde resin was studied. 13C‐NMR spin–lattice relaxation time (T1) measurements indicated that the molecular interactions were influenced by the concentration of THMP. Plots of T1 versus the concentration revealed an inflection point around 1.2 mol/L. Molecular orbital calculations of the THMP molecules implied the following features of the molecular interactions: in the concentration range below 1.0 mol/L, THMP existed as a single molecule, and then at a higher concentration, self‐association started. At concentrations higher than 1.5mol/L, almost all the THMP molecules were bimolecularly associated, and the formation of larger clusters was initiated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2849–2854, 2007
New method for evaluating adhesive property of fabrics and TPU: The rigid‐body pendulum rheometer approach
Authors: Chiu H. T. , Lee Patricia T. C.
Published: December 2006

Coating and laminating processes play an important role in textile industry. They are frequently used to produce fabric laminates during which the physical properties and appearance of textile fabrics are modified and enhanced. Currently, the adhesive property testing of a fabric laminate is done so by the use of pulling test machines such as Universal Tensile Tester, which measures the strength required to peel the tested materials apart. The adhesive test to date has not yet been performed using a newly developed machine, Rigid‐Body Pendulum Rheometer (RPR). This study was to establish a more effective method for fast‐evaluating adhesive properties of fabric laminates by assessing the performance of RPR. Specifically, RPR and Universal Tensile Tester were used to measure, respectively, the viscosity and peeling strength of PET/TPU (thermoplastic polyurethane) and nylon/TPU in response to UV exposure and water immersion. RPR can continuously observe and record viscosity behavior of tested samples in various temperature condition including from low temperature to high temperature, it not only measures viscosity speed, it also detects the differences in crosslinking and measures data generated during the softening process when the balanced time was achieved during the oscillations procedure. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2855–2863, 2007
Fundamental characterization of SBS‐modified asphalt mixed with sulfur
Authors: Chen J. S. , Huang C. C.
Published: December 2006

The purpose of this study was to characterize the mechanical behavior of asphalt modified by styrene–butadiene–styrene (SBS) and sulfur. Viscosity, microscopy, and rheological tests were conducted to understand the engineering properties of the polymer‐modified asphalt (PMA). Without the addition of sulfur, the polymer‐modified asphalt was microheterogeneous and was made up of two distinct finely interlocked phases, especially at high SBS concentrations. After the addition of sulfur, the PMA was observed to have smaller asphalt domains and a fairly homogeneous dispersion of the asphalt in the SBS matrix. The compatibility between polymer and asphalt produced an elastic network into the asphalt. The addition of sulfur resulted in an excellent elastic system and substantially increased the rheological properties of the PMA. Because of the colloidal nature of asphalt cements, their engineering properties were greatly improved because of the reinforcement of the SBS polymer and the physical‐chemical interaction between SBS and asphalt. The difference in the softening point between the top and bottom layers decreased significantly, and elastic recovery increased when was sulfur was present. A viscoelastic model was examined and shown to be appropriate for predicting the rheological properties ofthe asphalt–SBS blend mixed with sulfur. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2817–2825, 2007
Emulsifier‐free emulsion polymerization of styrene with 4‐vinylbenzoic acid: Kinetics and distribution of the carboxyl groups
Authors: Prasath R. Arun , Margarit‐Puri K. , Klapper M.
Published: December 2006

Carboxylated polystyrene particles were prepared by the batch emulsion polymerization of styrene (Sty) with 4‐vinylbenzoic acid (VBA) in the absence of an emulsifier with K2S2O8 as a free‐radical initiator. The effect changes in the ratio of potassium hydroxide to VBA and the concentration of VBA to Sty on the kinetics, monomer conversion, distribution of carboxyl groups, and particle size distribution were analyzed. The stability of the latices was evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2910–2919, 2007
On the overdrawing of melt‐spun isotactic polypropylene tapes
Authors: Schimanski Tilo , Loos Joachim , Peijs Ton , Alcock Ben , Lemstra Piet J.
Published: December 2006

The morphology and mechanical properties of melt‐spun and post‐drawn isotactic polypropylene (iPP) tapes have been studied in order to examine their dependence on the post‐draw ratio applied. Special attention is focused on the characterization of the so‐called overdrawing behavior of the tapes; at a certain draw ratio, a change of the optical appearance of the tape from transparent to opaque is observed. Overdrawing is accompanied with changes in the mechanical properties, surface, and morphology of the tapes. For post‐draw ratios without overdrawing, and for highly overdrawn tapes, the variation in the mechanical properties measured is very small, but for slightly overdrawn tapes, a large scattering of mechanical properties has been measured. In the latter case, this behavior is related to the start of internal delamination of the tapes during post drawing. It is shown that strongly overdrawn tapes have excellent mechanical properties, in particular, high specific stiffness and strength. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2920–2931, 2007
Solubility measurements of N2 and CO2 in polypropylene and ethene/octene copolymer
Authors: Li G. , Gunkel F. , Wang J. , Park C. B. , Altstädt V.
Published: December 2006

In this set of experiments a magnetic suspension balance (MSB) was employed to measure the apparent solubilities of N2 and CO2 in polypropylene (PP) and ethene/octene copolymer melts, while the swollen volume predicted by the Sanchez–Lacombe (SL) equation of state (EOS) was used to account for the buoyancy effect. The swollen volume of the polymer/gas mixture, as well as the gas solubilities for both PP and the ethene/octene copolymer, are discussed. It was observed that the branched molecular structure limited the molecular movement, and therefore the volume swelling of the polymer/gas mixture. In a similar context, the solubility of both N2 and CO2 were less in the branched polymer (ethene/octene copolymer) than in the linear PP. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2945–2953, 2007
Synthesis and characterization of carboxymethylated red angico (Anadenanthera macrocarpa) exudate polysaccharide
Authors: Oliveira Marilia A. , Silva Durcilene A. , Uchoa Daniel E. A. , Maciel Jeanny S. , Feitosa Judith P. A. , Paula Haroldo C. B. , de Paula Regina C. M.
Published: December 2006

Red angico is a heteropolysaccharide (arabinogalactan) obtained from Anadenanthera macrocarpa trees. Carboxymethylation of angico gum (AG) with monochloroacetic acid (MCA) in alkaline aqueous medium resulted in samples which were characterized by 13C nuclear magnetic resonance spectroscopy and gel permeation chromatography. The effects of reaction parameters, such as alkali concentration, MCA/AG ratio and temperature on the reaction yield and degree of substitution (DS) were investigated. The DS and MCA total efficiency values increase up to 2 h reaction time and then decrease. The DS varied from 0.11 to 1.10 depending on NaOH/MCA/AG ratio and temperature. The highest MCA total efficiency (0.57) was obtained for NaOH/MCA/AG molar ratio equal to 3:1:1, at 70°C. (DS = 0.63, yield = 91.0%). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) analysis shows that polymer degradation was observed in all samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2985–2991, 2007
Effects of spinning speed and heat treatment on the mechanical properties and biodegradability of poly(lactic acid) fibers
Authors: Park Chung Hee , Hong Eun Young , Kang Yun Kyung
Published: December 2006

We undertook this study to suggest the optimal spinning process conditions that provide a proper range of tenacity and biodegradability in textile fibers. The effect of melt‐spinning speed and heat treatment on the mechanical properties and biodegradability of poly(lactic acid) (PLA) fibers were investigated. PLA was spun at a high spinning speed of 2000–4000 m/min, and each specimen was heat‐treated. Mechanical properties were estimated by measurement of the breaking stress, and the degree of crystallinity was evaluated with wide‐angle X‐ray scattering. Biodegradability was estimated from the decreases in breaking stress, weight loss, and degree of crystallinity after soil burial. The results of the experiment reveal that heat treatment of the PLA fibers increased the breaking stress and crystallinity. With increasing spinning speed, breaking stress and crystallinity also increased. An increase in spinning speed was more effective than an increase in heat treatment for enhancing the breaking stress within the range of this study. From the soil burial test, it was revealed that an increase in spinning speed and heat treatment decreased the biodegradability of the fibers. X‐ray analysis of the soil‐buried fibers showed that fibers with higher crystallinities began to degrade more slowly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3099–3104, 2007
Preparation and properties of recycled HDPE/clay hybrids
Authors: Lei Yong , Wu Qinglin , Clemons Craig M.
Published: December 2006

Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could improve the compatibilization of RHDPE and clay. RHDPE/clay hybrids containing completely exfoliated clay were obtained using a two‐step blending method. Without compatibilizers, the clay could not be exfoliated, and it lowered the crystallization peak temperature, crystallinity level, and the long period of RHDPE. MAPE and clay layers could act as heterogeneous nucleating agents for RHDPE. The titanate had a little influence on crystallization behavior of RHDPE. Adding clay to RHDPE reduced the impact strength but had little influence on the tensile strength. Both the storage and loss moduli increased with up to 5% of clay in hybrids containing CAPS, and there was an about 44% increase in impact strength of RHDPE/clay hybrid containing 5% MAPE compared with that of the hybrid containing no MAPE. The clay presence lowered the thermal stability of RHDPE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3056–3063, 2007
Synthesis and characterization of composite magnetic microspheres of artemisia seed gum and chitosan
Authors: Zhang Ji , Zhang Shengtang , Wang Yunpu , Gao Sufang
Published: December 2006

In this study, composite magnetic microspheres of artemisia seed gum and chitosan were prepared in a well‐shaped spherical form with a size range of 230–460 μm by the suspension crosslinking technique for use in the application of magnetic carrier technology. The magnetic material used in the preparation of the composite microspheres was prepared by precipitation from FeCl3 and FeSO4 solution in basic medium. The morphological, magnetic properties, and the functional groups of the microspheres were characterized by different techniques (i.e., SEM, magnetometry, and FTIR). The results demonstrated that the stirring rate of the suspension and the Fe3O4/chitosan ratio are the most effective parameters for the average of the size distributions and the magnetic quality of the microspheres, while the amount of artemisia seed gum and Tween‐80 have no significant effect on these properties. The best magnetic quality of the composite magnetic microspheres is around 4.08 emu/g microspheres at 10 KG magnetic field intensity. The thermal stability of the composite magnetic microspheres was measured by using DSC methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3045–3049, 2007
Preparation and characterization of carboxymethyl konjac glucomannan/sodium montmorillonite hybrid films
Authors: Lu Jun , Xiao Chaobo
Published: December 2006

Carboxymethyl konjac glucomannan (CKGM)/ sodium montmorillonite (MMT) hybrid films of various compositions were prepared by casting from a polymer/silicate water suspension. The structure and properties of the hybrid films were investigated by wide angle X‐ray diffraction (WAXD), transmission electron microscopy (TEM), attenuated total reflection infrared spectroscopy (ATR‐IR), differential scanning calorimetry (DSC), and tensile tests. The results from WXRD and TEM indicated that an intercalated CKGM/MMT nanocomposite film was obtained by polymer solution intercalation. WXRD and DSC showed that the high‐Tm crystal phase was induced by the presence of lower MMT loading, but the Tm of the hybrid films became weak with the increase of MMT content due to the polymer confinement. The hybrid films showed higher thermal stability and mechanical properties than that of the neat polysaccharide due to the strong interaction between hydroxyl and carbonyl group of CKGM and the silicate layer of MMT. Furthermore, the degree of swelling of the hybrid films was investigated in acidic buffer solutions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2954–2961, 2007
Effect of halide ions on the corrosion inhibition of aluminium in alkaline medium using polyvinyl alcohol
Authors: Umoren S. A. , Ebenso E. E. , Okafor P. C , Ekpe U. J. , Ogbobe O.
Published: December 2006

The corrosion inhibition of aluminum in NaOH in the presence of polyvinyl alcohol (PVA) at 30 and 40°C and the effect of addition of halides (KCl, KBr, KI) were studied using weight loss and hydrogen evolution methods. Results obtained showed that PVA acts as a corrosion inhibitor in the alkaline environment. The inhibition efficiency increased with increase in concentration of PVA and synergistically increased on the addition of the halides but however decreased with rise in temperature. The phenomenon of physical adsorption is proposed from the obtained Ea and Qads values. PVA was found to obey Freundlich and Frumkin adsorption isotherms. The increase in inhibition efficiency I (%), surface coverage θ values as well as synergistic parameter, SI were found to be in the order I− > Br− > Cl−, which clearly indicates that the radii and electronegativity of the halides play a significant role in the adsorption process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2810–2816, 2007
Noncatalytic hydrogenation of natural rubber latex
Authors: Mahittikul A. , Prasassarakich P. , Rempel G. L.
Published: December 2006

Hydrogenation is an important method of chemical modification, which improves the physical, chemical, and thermal properties of diene‐based elastomers. Natural rubber latex (NRL) could be hydrogenated to a strictly alternating ethylene–propylene copolymer using diimide generated in an in situ system. The diimide generated using the in situ technique for hydrogenation of NRL was accomplished by thermolysis of p‐toluenesulfonyl hydrazide (TSH). A molar ratio of TSH to double bonds equal to 2 : 1 was found to be the optimum ratio to provide a high percentage of hydrogenation. 95% Degree of saturation of NRL was achieved in o‐xylene. Hydrogenated products are characterized by FTIR and NMR spectroscopy. The thermal stability of hydrogenated rubber was improved as shown from the results of thermogravimetric analysis. From the differential scanning calorimetry measurement, the glass transition temperature of the hydrogenated product did not appear to change. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2885–2895, 2007
Properties of polymer‐modified mortars based on methyl methacrylic latexes with emulsifier contents and various monomer ratios
Authors: Hyung Wongil , Mun Kyungju , Kim Wanki
Published: December 2006

This study investigates the effects of the emulsifier content and monomer ratio on the typical properties of the polymer‐modified mortars with methyl‐methacrylate–butyl‐acrylate (MMA/BA) and methyl‐methacrylate–ethyl‐acrylate (MMA/EA) latexes and obtains basic data necessary to develop appropriate latexes for cement modifiers. The polymer‐modified mortars using the MMA/BA and MMA/EA latexes polymerized with emulsifier contents and at various monomer ratios are prepared for different polymer–cement ratios, and tested to obtain the particle size of the polymer latexes, the glass transition temperature of the polymer film, air contents, water–cement ratios, flexural and compressive strengths, water absorption, and chloride ion penetration. From the test results, the polymer‐modified mortars using MMA/BA and MMA/EA latexes with the mix proportions of synthesis having emulsifier contents of 5–6% and monomer ratios of 50 : 50 to 60 : 40 for the appropriate mix proportions can be recommended for practical applications. The basic properties of the polymer‐modified mortars are more affected by the polymer–cement ratio rather than the monomer ratio and emulsifier content, and are improved over unmodified mortar. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3010–3018, 2007
Synthesis and evaluation of novel injectable and biodegradable polyglycolide‐based composites
Authors: Xie Dong , Park Jong‐Gu , Zhao Jun
Published: December 2006

Novel 3‐arm methacrylate‐endcapped biodegradable polyglycolide prepolymer was synthesized and characterized. Injectable and in situ curable composites formulated with the liquid prepolymer and bioabsorbable β‐tricalcium phosphate were prepared. The pastelike composites were cured at room temperature using a redox‐initiation system. The initial compressive strengths (CSs), curing time, exotherm, and degree of conversion of the cured composites were determined. The composites showed initial yield CS ranging from 20.1 to 92.3 MPa, modulus from 0.73 to 5.65GPa, ultimate strength from 119.9 to 310.5 MPa, and toughness from 630 to 3930 N mm. Increasing filler content increased yield strength and modulus but decreased ultimate strength and toughness. Diametral tensile strength test showed the same trend as did CS test. Increasing filler content also increased curing time but decreased exotherm and degree of conversion. During the course of degradation, all the materials showed a significant burst degradation behavior within 24 h, followed by a significant increase in strength between Day 1 and Day 3, and then continuous degradation until no strength was detected. The composites with higher filler content retained their strengths longer but those with lower filler contents lost their strengths in 45 or 60 days. The degradation rate is filler‐content dependent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2977–2984, 2007
Microphase separation, stress relaxation, and creep behavior of polyurethane nanocomposites
Authors: Xia Hesheng , Song Mo , Zhang Zhongyi , Richardson Mel
Published: December 2006

The stress relaxation and creep behavior of blank polyurethane (PU) and PU/clay nanocomposites were investigated. The relaxation time spectrum and retardant time spectrum were derived according to the generalized Maxwell model and Voigt model with a Tikhonov regularization method, respectively. The characteristic relaxation time was identified with the corresponding relaxation process. At a small strain, the relaxation was mainly attributed to uncoiling/disentangling of soft segment chain network in the soft phase, with a single characteristic relaxation time in the range of 5–100 s. The increase in the hard segment content leads to a decrease in the relaxation time, and the addition of clay leads to an increase in the relaxation time. At large strains, the multipeak relaxations occurred, and they were attributed to the breakup of interconnected hard domains and pullout of soft segment chains from hard domains, together with the disentangling of soft segment chain network in the soft phase. The creep results are consistent with those of the stress relaxation. The relaxation and creep behavior were related to microphase separation of PU. This study suggested that the relaxation spectrum can be used to examine the complicated relaxation processes for a multiphase and multicomponent polymer system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2992–3002, 2007
Adsorption of guanosine, cytidine, and uridine on a β‐cyclodextrin derivative grafted chitosan
Authors: Xiao Jian Bo
Published: December 2006

A β‐cyclodextrin derivative grafted chitosan (CDD‐C) was synthesized with chitosan and carboxymethyl‐β‐cyclodextrin (β‐CD). Its structure was characterized by elemental, infrared spectra, and X‐ray diffraction analyses. The degree of substitution by the carboxymethyl‐β‐CD moiety achieved 0.27 with the addition of DMF to the reaction solution. The results are in agreement with the expectations. The static adsorption properties for guanosine, cytidine, and uridine were studied. Experimental results demonstrated that CDD‐C had higher adsorption capability for guanosine than cytidine and uridine, and the adsorption capacity for guanosine was 74.20 mg/g. The adsorption capacity was greatly influenced by pH, time, and temperature. The introduction of chitosan enhanced the adsorption ability and adsorption selectivity of β‐CD for guanosine. This novel derivative of chitosan is expected to have wide applications in separation, concentration, and analysis of guanosine, cytidine, and uridine in biological sample. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3050–3055, 2007
Chitosan‐grafted poly(hydroxyethyl methacrylate‐co‐glycidyl methacrylate) membranes for reversible enzyme immobilization
Authors: Yakup Arıca M. , Yilmaz Meltem , Bayramoğlu Gülay
Published: December 2006

Epoxy group‐containing poly(hydroxyethyl methacrylate/glycidyl methacrylate), p(HEMA/GMA), membrane was prepared by UV initiated photopolymerization. The membrane was grafted with chitosan (CH) and some of them were chelated with Fe(III) ions. The CH grafted, p(HEMA/GMA), and Fe(III) ions incorporated p(HEMA/GMA)‐CH‐Fe(III) membranes were used for glucose oxidase (GOD) immobilization via adsorption. The maximum enzyme immobilization capacity of the p(HEMA/GMA)‐CH and p(HEMA/GMA)‐CH‐Fe(III) membranes were 0.89 and 1.36 mg/mL, respectively. The optimal pH value for the immobilized GOD preparations is found to have shifted 0.5 units to more acidic pH 5.0. Optimum temperature for both immobilized preparations was 10°C higher than that of the free enzyme and was significantly broader at higher temperatures. The apparent Km values were found to be 6.9 and 5.8 mM for the adsorbed GOD on p(HEMA/GMA)‐CH and p(HEMA/GMA)‐CH‐Fe(III) membranes, respectively. In addition, all the membranes surfaces were characterized by contact angle measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3084–3093, 2007
Swelling and mechanical behavior of modified poly(vinyl alcohol)/laponite nanocomposite membranes
Authors: Nair Shubhangi H. , Pawar Kiran C. , Jog Jyoti P. , Badiger Manohar V.
Published: December 2006

Nanocomposite (NC) membranes based on hydrophobically modified PVA and laponite were synthesized with varying laponite content in the feed. The incorporation of laponite in NC membranes was investigated by FTIR spectroscopy and thermogravimetric analysis. The swelling ratio of membranes was determined as a function of temperature and laponite content. Swelling studies of NC membranes exhibited the decrease in swelling with an increase in laponite content in the NC membranes. The swelling ratio of NC membrane with 20% laponite slightly increased with an increase in temperature. Dynamic mechanical analysis showed the systematic increase in storage modulus with laponite content, which indicates the enhancement of mechanical property upon laponite addition. There was also a decrease in the tan δ peak values of NC membranes with an increase in laponite content in NCs. The permeabilities through NC membranes as a function of solute size and laponite content were studied and the results showed molecular screening based on size. The permeability of solute reduced due to the presence of well‐dispersed laponite in the NC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2896–2903, 2007
Nonisothermal cure kinetics of DGEBA with novel aromatic diamine
Authors: Ghaemy M. , Barghamadi M. , Behmadi H.
Published: December 2006

The effect of the molar ratio of diglycidyl ether of a bisphenol‐A based epoxy (DGEBA) and synthesized 4‐phenyl‐2,6‐bis(4‐aminophenyl)pyridine (PAP) as curing agent during nonisothermal cure reaction by the Kissinger, Ozawa, and isoconversional equations was studied. The cure mechanism was studied by FTIR analysis. Kinetic analysis of the curing reaction of DGEBA at two different concentrations (42 and 32 phr) of the curing agent was studied by using DSC analysis. With an increasing PAP content, the pre‐exponential factor increased by increasing collision probability between epoxide and primary or secondary amine groups in noncataltyic or catalytic modes. The activation energy also increased because of the increasing content of crosslink density. The activation energies obtained from three equations were in good agreement. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3076–3083, 2007.
Structural, morphological, and dynamic mechanical properties of Zn‐filled Nylon 11
Authors: Pande S. A. , Kelkar D. S. , Peshwe D. R.
Published: December 2006

Nylon 11 samples were filled with metal (Zn) fillers of two different concentrations (1 and 5% w/w) each. The samples in the form of disc were obtained by using hot press molder. The structural properties have been investigated using density measurement and wide angle X‐ray diffraction (WAXD) technique. The morphology of pure and Zn‐filled samples has been studied using scanning electron microscopy. Glass transition (Tg) temperature was determined using dynamic mechanical thermal analyzer (DMTA). The result shows that there is slight crystal modification due to the addition of metal fillers (Zn), and the crystallinity has improved. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3094–3098, 2007
Polyimides 7: Synthesis, characterization, and properties of novel soluble semifluorinated poly(ether imide)s
Authors: Kute Vijay , Banerjee Susanta
Published: December 2006

Three novel diamine monomers (VI, VII, and VIII) were synthesized. These diamine monomers lead to a number of semifluorinated poly(ether imide)s when reacted with different commercially available dianhydrides like pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2‐bis (3,4‐dicarboxyphenyl) hexafluoropropene (6FDA), and oxydiphthalic dianhydride (ODA) by thermal imidization route. Elemental analyses, IR and NMR techniques were used to characterize the monomers and polymers. The resulting polymers exhibited weight average molar masses up to 1.78 × 105 g mol−1 in GPC with respect to polystyrene standard and have very good solubility in several organic solvents such as NMP, DMF, DMAC, DMSO, chloroform, and THF. Very good solubility of these polymers in CDCl3 enables their complete characterization by proton as well as 13C‐NMR techniques. The polymers showed very high thermal stability with decomposition temperature (5% weight loss) up to 511°C in air and high glass transition temperature up to 311°C depending upon the exact repeating unit structure. The polymer films showed high modulus (up to 2.9 GPa) as was evaluated by DMA. The polymers also showed very low water absorption (0.16%), low dielectric constant (2.35 at 1MHz) and very good optical transmission. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3025–3044, 2007
Kinetic study of the curing of mixtures of DGEBA and five‐membered cyclic carbonates with lanthanum triflate as cationic initiator
Authors: Cervellera Roser , Ramis Xavier , Salla Josep M. , Mantecón Ana , Serra Angels
Published: December 2006

Mixtures of diglycidylether of bisphenol A (DGEBA) with 1,3‐benzodioxolane‐2‐one (CC) or 4‐phenoxymethyl‐1,3‐dioxolane‐2‐one (PGEC) were cured in the presence of lanthanum triflate. FTIR/ATR was used to study the evolution of carbonate and epoxide groups to follow the reactive processes that take place during curing. DSC was applied to study the thermal characteristics of the curing process and to determine the glass‐transition temperatures of the cured materials. The kinetics of the curing was studied isothermally by means of FTIR and the kinetic model was selected through the isokinetic relationships. DSC experiments were used to study the kinetics in nonisothermal conditions by means of isoconversional procedures and the Coats–Redfern and Criado methodologies. By TMA we could monitor the evolution of the shrinkage during isothermal curing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2875–2884, 2007
Superoxide Compounds of the Large Pseudo‐Alkali‐Metal Ions Tetramethylammonium, ‐Phosphonium, and ‐Arsonium
Authors: Dietzel Pascal D. C. , Kremer Reinhard K. , Jansen Martin
Published: December 2006

Compounds of the three large cations tetramethylammonium, tetramethylphosphonium, and tetramethylarsonium with the superoxide radical anion were synthesized by either metathesis or ion exchange in liquid ammonia. They were obtained from concentrated solutions as ammoniates in the form of long needle‐shaped single crystals. [N(CH3)4]‐(O2)⋅3NH3 crystallizes in the monoclinic crystal system, whereas the two compounds [E(CH3)4](O2)⋅2NH3 (E=P, As) are isostructural and belong to the orthorhombic crystal system. The cation–anion packing in all three crystal structures is related to the sodium chloride structure. All structures contain hydrogen bonds between the ammonia molecules and between ammonia and the superoxide. The solvent of crystallization was easily released from the crystals upon complete removal of the solvent from the reaction vessel, leading to polycrystalline samples. The Raman spectra of all three solvent‐free compounds show the symmetric stretching mode of the superoxide ion at about 1123 cm−1. The desolvated [N(CH3)4](O2) was investigated by powder X‐ray diffraction, and the crystal structure was solved by ab initio simulated annealing methods by using rigid‐body models of the constituent molecular ions. The superoxide ion shows rotational disorder. The magnetic susceptibility of tetramethylammonium superoxide follows the Curie–Weiss law with a high‐temperature effective magnetic moment of 1.66(3) μB and a paramagnetic Curie temperature of Θ=−13(6) K. Complementary electron paramagnetic resonance spectroscopy revealed that the average g factor is temperature‐dependent. It decreased from 2.15 at 10 K to 1.66 at 100 K, possibly due to the onset of rotational motion of the superoxide ion and in accordance with the lower‐than‐expected effective magnetic moment.
Dose‐linear pharmacokinetics of oleanolic acid after intravenous and oral administration in rats
Authors: Jeong Dong Won , Kim Young Hoon , Kim Hui Hyun , Ji Hye Young , Yoo Sun Dong , Choi Won Rack , Lee Soo Min , Han Chang‐Kyun , Lee Hye Suk
Published: December 2006

The pharmacokinetics of oleanolic acid was evaluated in vitro and in vivo. From Caco‐2 cell permeation studies, oleanolic acid was a low permeability compound with no directional effects, suggesting a low in vivo absorption mediated by a passive diffusion. Oleanolic acid was metabolically unstable following incubation with rat liver microsomes in the presence of NADPH. After intravenous injection at doses of 0.5, 1 and 2 mg/kg doses, oleanolic acid showed dose‐linear pharmacokinetics as evidenced by unaltered CL (28.6–33.0 ml/min/kg), Vss (437–583 ml/kg), dose‐normalized AUC (16.0–17.9 µg min/ml based on 1 mg/kg) and t1/2 (41.9–52.7 min). Following oral administration of oleanolic acid at doses of 10, 25 and 50 mg/kg, Tmax, t1/2, dose‐normalized Cmax (66–74 ng/ml based on 25 mg/kg) and dose‐normalized AUC (5.4–5.9 µg min/ml based on 25 mg/kg) were comparable between 25 and 50 mg/kg dose, but the plasma concentrations at 10 mg/kg dose were not measurable as they were below the limit of quantitation (2 ng/ml). The absolute oral bioavailability was 0.7% for oral doses of 25 and 50 mg/kg. The extent of urinary excretion was minimal for both i.v. and oral doses. The very low oral bioavailability of oleanolic acid could be due to a poor absorption and extensive metabolic clearance. Copyright © 2007 John Wiley & Sons, Ltd.
In vitro activation of the corticosteroid ciclesonide in animal nasal mucosal homogenates
Authors: Sato H. , Nave R. , Nonaka T. , Mochizuki T. , Takahama S. , Kondo S.
Published: December 2006

Ciclesonide, a new corticosteroid for allergic rhinitis, is administered as an inactive parent compound that is converted by esterases to the pharmacologically active metabolite, desisobutyryl‐ciclesonide (des‐CIC). This study investigated the in vitro activation of ciclesonide in nasal mucosa of multiple animal species. Nasal mucosal homogenates from rats, guinea‐pigs, rabbits and dogs were incubated with ciclesonide 0.5 µmol/l (0.271 µg/ml) or 5 µmol/l (2.71 µg/ml) for up to 120 min. Concentrations of ciclesonide and des‐CIC were measured by high‐performance liquid chromatography with tandem mass spectrometry. Ciclesonide was metabolized to des‐CIC in nasal mucosal homogenates of each species. The initial velocities of des‐CIC formation ranged from 0.0038 to 0.0150 nmol/min/mg protein and 0.0319 to 0.0983 nmol/min/mg protein in nasal mucosal homogenates incubated with ciclesonide 0.5 µmol/l and 5 µmol/l, respectively. Furthermore, the initial velocities of ciclesonide metabolism ranged from 0.0032 to 0.0142 nmol/min/mg protein and 0.0445 to 0.1316 nmol/min/mg protein in nasal mucosal homogenates incubated with ciclesonide 0.5 µmol/l and 5 µmol/l, respectively. This study confirms that ciclesonide is converted to des‐CIC in nasal mucosal homogenates without any marked differences among animal species. Copyright © 2007 John Wiley & Sons, Ltd.