bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuropathological findings in West Nile virus encephalitis: A case report
Authors: Agamanolis Dimitri P. , Leslie Michael J. , Caveny Elizabeth A. , Guarner Jeannette , Shieh Wun‐Ju , Zaki Sherif R.
Published: September 2003

A 67‐year‐old woman had fever, myalgias, progressive weakness, and respiratory insufficiency. In 9 days, flaccid areflexic quadriparesis and bulbar palsy developed. She died 26 days after the onset of her illness. Serum and cerebrospinal fluid serology were positive for West Nile virus. Neuropathological study showed changes consistent with a viral encephalomyelitis, similar to poliomyelitis. The brainstem showed neuronal loss and multiple foci of necrosis. The spinal cord showed severe loss of anterior and posterior horn neurons. Immunohistochemistry identified West Nile virus antigens in the brainstem and spinal cord. Paralysis, in West Nile virus encephalitis, is caused by destruction of motor neurons. Ann Neurol 2003;54:547‐551
Development of polymer‐molding‐releasing metal mold surfaces with perfluorinated‐group‐containing polymer plating
Authors: Mori Kunio , Sasaki Yaeko , Hirahara Hidetoshi , Oishi Yoshiyuki
Published: September 2003

The polymer‐molding‐releasing properties of metal molds were found to be related to the following factors: (1) interfacial chemical bonding between the surfaces of polymers and metal molds and (2) a friction force or friction coefficient between polar substances and/or low‐molecular‐weight components in the polymers and physical factors on mold surfaces. We theoretically and experimentally confirmed that metal molds with good polymer‐molding‐releasing properties had very small surface free energies. We also proved that the surface free energies in the resulting polymer moldings were lower than before shaping. The molding releasing properties improved with decreasing friction force and friction coefficient between the surface of polymers and metal molds and with decreasing surface free energy. To obtain metal molds with lower surface free energies, we developed a polymer plating method with perfluorinated‐group‐containing triazine dithiol. The Metal mold treated by polymer plating had lower critical surface tension (7.5 mJ/m2) than Teflon (18 mJ/m2), indicating that the surface consisted of CF3− groups. The treated mold showed excellent durability in its releasing properties, which was better than that of the untreated mold. This technique was developed for the production of molds for the Fθ lens and the naturally bright focusing screen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2549–2556, 2003
Effect of reinforcement type and length on physical properties, surface quality, and cycle time for sheet molding compound (SMC) compression molded parts
Authors: Boylan Sarah , Castro Jose M.
Published: September 2003

One of the fastest growing applications of sheet molding compound (SMC) compression molding is the manufacture of truck body panels. The trucking industry requires parts with high strength and stiffness, but the surface quality is also important. In this study, the effect of reinforcement type and length on physical properties, surface quality, and cycle time are evaluated. In particular, the effect of different lengths of carbon fibers and glass fibers with different sizing are studied. It was found that for the same volume percent, carbon fibers greatly improve the stiffness of the SMC at the sacrifice of strength and surface quality and also require larger fill times for the same molding force, as compared to glass fibers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2557–2571, 2003
Proton exchange membranes by grafting of styrene–acrylic acid onto FEP by preirradiation technique. I. Effect of synthesis conditions
Authors: Phadnis Swati , Patri M. , Hande Varsha R. , Deb P. C.
Published: September 2003

Grafting of styrene–acrylic acid (sty–AA) polymer onto fluorinated ethylene propylene copolymer (FEP) was carried out by preirradiation of FEP with γ‐rays. Effect of reaction conditions on the degree of grafting such as total radiation dose, monomer concentration, temperature, and time of grafting has been studied. From the study, it is seen that the degree of grafting is strongly dependent on the reaction conditions. The rate dependence of 0.53 (∼0.5) and 1.03 (∼1) have been obtained with respect to total dose and monomer concentration, respectively indicating that radiation induced grafting follows free radical polymerization. The activation energy for the grafting in the temperature range of 60–90°C is found to be 33 kJ/mol. The results indicate that the grafting takes place by the front mechanism where the grafting starts at surface and slowly proceeds inwards by diffusion of the monomer through the swollen grafted chains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2572–2577, 2003
Effect of molecular structure of styrene–butadiene block copolymers on morphology, rheological properties, and impact strength of polystyrene/polyethylene blends
Authors: Fortelný Ivan , Mikešová Jana , Hromádková Jiřina , Hašová Věra , Horák Zdeněk
Published: September 2003

The effect of molecular structure of six model styrene–butadiene (SB) block copolymers with various number of blocks and two lengths of styrene blocks on morphology, rheological properties, and impact strength of polystyrene (PS)/high‐density polyethylene (PE) blends was studied. It was found that location of SB copolymers in the blends is determined by the length of styrene blocks. The length of styrene blocks has similar effects on impact strength and linear viscoelastic properties of the blends. On the other hand, the correlation was not found between the effects of a number of blocks on impact strength and linear viscoelastic properties of the blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2303–2309, 2003
Polymer gel electrolytes based on thermoplastic polyurethane
Authors: Tian Li‐ying , Zhu Wei‐hua , Tang Xiaozhen
Published: September 2003

Series of gel electrolytes based on thermoplastic polyurethane (PU) with different organic additives were prepared and studied. Structural characterization was carried out by differential scanning calorimetry (DSC), dynamic mechanical analyzer (DMA), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The results showed that propylene carbonate (PC), N,N‐dimethylformamide (DMF), polyethyleneglycol 400 (PEG400), and glycerol played roles of plasticizers and were miscible with soft‐segment in PU matrix, which led to increase of the polymer segmental mobility, which in turn led to decrease of glass transition temperature (Tg), while, diethyl carbonate (DEC) and diethylene glycol dimethyl ether (DGDE) showed no effectiveness of plasticizers. Ionic conductive properties of the electrolytes, examined by complex impedance analyzer, showed that ionic conductivities of the samples increased with the increase of organic additive content, and the sample with PEG400 as organic additive showed an ionic conductivity of 1.8 × 10−5 S cm−1 at room temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2310–2315, 2003
Mechanical and thermal properties of phenolic resin‐layered silicate nanocomposites synthesized by melt intercalation
Authors: Choi Min Ho , Chung In Jae
Published: September 2003

Phenolic resin–layered silicate nanocomposites (PLSNs) were synthesized by melt intercalation with linear novolac resin (P1) and organosilicates such as montmorillonite modified by benzyldimethyloctadecylammonium (C18BM) and by bis(2‐hydroxy‐ethyl)methyl tallow ammonium (THEM). The PLSNs were prepared by a sequential process (IC) in which phenolic resin was melt‐intercalated into organosilicate and subsequently cured with hexamethylenetetramine (HMTA). It was found from X‐ray diffraction measurements that P1THEMIC nanocomposites showed better silicate dispersion than did P1C18BMIC nanocomposites, even though both systems had intercalated morphologies. The larger silicate gallery expansion in P1THEMIC nanocomposites was attributed to the strong hydrogen‐bonding interaction between the phenolic resin and hydroxyl groups of the organic modifier of THEM. As they had better silicate dispersion, the P1THEMIC nanocomposites showed better mechanical properties than the P1C18BMIC nanocomposites. The thermal stability of the P1THEMIC nanocomposites was slightly increased or decreased, depending on the silicate content, relative to the neat phenolic resin. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2316–2321, 2003
Compatibilization of polymer blends from poly(styrene‐co‐acrylonitrile) and polycarbonate by oxazoline modification of poly(styrene‐co‐acrylonitrile) in the melt
Authors: Gordon Becker Hinnerk , Schmidt‐Naake Gudrun
Published: September 2003

A good way of achieving compatibility in polymer blends of poly(styrene‐co‐acrylonitrile) (S/AN) and bisphenol A polycarbonate (PC) is the chemical modification of S/AN in the melt. A catalyzed reaction of the nitrile groups with a substituted 2‐amino alcohol or 2‐amino phenol resulted in a conversion of nitrile groups of 55–75% in 60 min. The introduced heterocyclic structures were ethyl hydroxymethyl oxazoline (EHMOXA) and benzoxazole (BenzOXA), respectively. The use of dibutyltin oxide as a catalyst led to the highest efficiency. The modified polymer was characterized by Fourier transform infrared and NMR spectroscopy, elemental analysis, and reactions with organic acids and anhydrides. The modified S/AN showed good technical compatibility (single glass‐transition temperature) with PC in blends made from solution and from the melt. All blends were characterized with oscillating rheometry and differential scanning calorimetry. Rheological measurements showed that EHMOXA–S/AN reacted with PC and had crosslinked structures, whereas BenzOXA–S/AN showed compatibilization without any (crosslinking) reaction. The melt blends of BenzOXA–S/AN and PC showed a downward shift in the complex viscosity due to the influence of the BenzOXA group. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2322–2332, 2003
Synthesis and characterization of conducting poly(aniline‐co‐diaminodiphenylsulfone) copolymers
Authors: Dan Ananya , Sengupta P. K.
Published: September 2003

Polyaniline, poly(aniline‐co‐4,4′‐diaminodiphenylsulfone), and poly(4,4′‐diaminodiphenylsulfone) were synthesized by ammonium peroxydisulfate oxidation and characterized by a number of techniques, including infrared spectroscopy, ultraviolet–visible absorption spectroscopy, 1H‐NMR, thermogravimetric analysis, and differential scanning calorimetry. These copolymers had enhanced solubility in common organic solvents in comparison with polyaniline. The conductivities of the HCl‐doped polymers ranged from 1 S cm−1 for polyaniline to 10−8 S cm−1 for poly(4,4′‐diaminodiphenylsulfone). The copolymer compositions showed that block copolymers of 4,4′‐diaminodiphenylsulfone (r1 > 1) and aniline (r2 < 1) formed and that the reactivity of 4,4′‐diaminodiphenylsulfone was greater than that of aniline. The results were explained by the effect of the SO2 group present in the polymer structure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2337–2347, 2003
Reducing the contents of free phenol and formaldehyde in phenolic foam
Authors: Li Wanli , Lin Qiang , Yan Mingfa , Zou Yousi
Published: September 2003

The problem of overly high contents of remnant monomers (free phenol and free formaldehyde) in phenolic foam was studied. Free phenol was characterized by iodimetry, and free formaldehyde was characterized by a hydroxylamine hydrochloride method. The effect of the phenol/formaldehyde molar ratios and the reaction temperature on the contents of the remnant monomers was examined. The effect of adding urea on the content of free formaldehyde was investigated. The effect of the foaming process on the contents of the remnant monomers was examined in detail. Phenolic foams in which the content of free phenol was 0.09% and the content of free formaldehyde was less than 0.1% were successfully prepared. A prepolymer of polyurethane, which toughened the phenolic foam, lowered the contents of free phenol and free formaldehyde. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2333–2336, 2003
On the correlation between characteristics of topological and molecular structures and mechanical properties of NR/chlorinated polyethylene rubbers
Authors: Jurkowska Barbara , Jurkowski Boleslaw
Published: September 2003

Chlorinated polyethylene (CPE) taken as a modifier for NR rubber compound changes the mechanical properties of their vulcanizates. With the help of a novel thermomechanical methodology it was found that it also influences the structures of both the tested master batches and the vulcanizates. Some characteristics of the structure of NR/CPE rubbers obtained by using thermomechanical analysis (TMA) correlate satisfactorily with their mechanical properties measured at static and dynamic conditions. This supports our previous conclusion about the suitability of TMA to study some of the underlying reasons for changes in rubber properties resulting from rubber formulation, compounding, and processing. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2583–2591, 2003
Thermoplastic elastomeric blend of nitrile rubber and poly(styrene‐co‐acrylonitrile). II. Replacement of nitrile rubber by its vulcanizate powder
Authors: Anandhan S. , De P. P. , Bhowmick Anil K. , De S. K. , Bandyopadhyay S.
Published: September 2003

A model waste nitrile rubber powder (w‐NBR) was prepared by ambient grinding of aged NBR vulcanizate based on an oil seal formulation. The w‐NBR was characterized by scanning electron microscopic and optical microscopic techniques. Virgin nitrile rubber in a thermoplastic elastomeric 70:30 nitrile rubber/poly(styrene‐co‐acrylonitrile) (SAN) blend was replaced by w‐NBR, and the mechanical properties and swelling index were determined. The virgin NBR in the blend was replaced by the rubber present in w‐NBR (r‐w‐NBR) and the optimum mechanical properties were achieved at 45% replacement where the blend was still reprocessable. Transmission electron microscopic and atomic force microscopic studies reveal that w‐NBR particles coated with NBR are dispersed in a continuous SAN matrix. It was observed that migration of unreacted curatives from w‐NBR to virgin NBR is not significant and incorporation of curatives is necessary for attainment of optimum level of mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2348–2357, 2003
1H T2‐NMR monitoring of crosslinked polyolefin aging
Authors: Harris Douglas J. , Assink Roger A. , Gillen Kenneth T.
Published: September 2003

This work examines the correlation between the 1H‐NMR T2 relaxation constant and the mechanical properties of aged crosslinked polyolefin cable insulation. T2 experiments on unswollen samples could not differentiate between unaged and highly aged materials; all exhibited 1H T2 constants of approximately 0.5 ms. To accentuate the effects of aging, samples were swollen in various solvents. Unaged samples had T2 values of approximately 15 ms in good solvents. With thermal aging, T2 values decreased as the ultimate tensile elongation decreased. However, the correlation between T2 and elongation differed for samples irradiated with high‐energy radiation and for materials aged above versus below the crystalline melting temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2578–2582, 2003
Compatibilization of PE/PS and PE/PP blends. I. Effect of processing conditions and formulation
Authors: Kallel Tasnim , Massardier‐Nageotte Valérie , Jaziri Mohamed , Gérard Jean‐François , Elleuch Boubaker
Published: September 2003

The objective of this work was to study the effectiveness of low‐cost commercial compatibilizers and several processes (internal mixer, single‐ and twin‐screw extruders) for two types of plastic blends: high‐density polyethylene/polypropylene and high‐density polyethylene/polystyrene blends, to gain insight into the recycling of wastes from those frequently encountered mixed plastics. Blends going from a pure A to a pure B component, with and without a compatibilizer, were prepared using an internal mixer, a corotating twin‐screw extruder, as well as a single‐screw extruder to follow an industrial‐convenient process. In both cases, the analyses of blend morphologies highlighted the poor adherence between the two phases in the uncompatibilized blends. Compatibilized blends display better adherence between phases and the ability to process blends made from both single‐ and twin‐screw extruders. When adding a compatibilizer, the viscosity of each blend (PE/PP or PE/PS) increased due to a better adhesion of the phases. Charpy impact tests showed that the presence of the compatibilizer in PE/PS blends increased their impact properties. Indeed, the improvement of the adhesion between the two phases enabled stress transfer at the interface. A single‐screw extruder seems to be efficient as a processing method on an industrial scale when a compatibilizer is used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2475–2484, 2003
Influence of the reaction mechanism on the shape accuracy of optical components obtained by photoreplication
Authors: Verstegen E. J. K. , Faasen J. H. P. , Stapert H. R. , Duineveld P. C. , Kloosterboer J. G.
Published: September 2003

Light‐induced crosslinking polymerization of both bis‐methacrylates and bis‐epoxides yields highly transparent glassy products, suitable for optical applications. Rheological changes of vitrifying liquids during photopolymerization strongly influence the shape accuracy of the final product. Comparison of a free‐radical‐initiated methacrylate polymerization and a cationically initiated ring‐opening polymerization of an epoxide showed that different reaction mechanisms led to very different chemorheological responses and, hence, to pronounced differences in the shape accuracy of the products obtained with either of these materials. An ethoxylated bisphenol‐A dimethacrylate (HEBDM) gels below 1–2% conversion and vitrifies at 15%. At higher conversion, large stresses develop through polymerization shrinkage. Relaxation occurs upon release of a product from its mold, leading to large shape deviations. Ring‐opening polymerization of the diglycidyl ether of bisphenol‐A (DGEBA) has an intrinsically lower polymerization shrinkage. Moreover, gelation of DGEBA polymer networks occurs at 25–30% conversion, leading to much lower stresses since most of the volume change occurs in the liquid state in which replenishment of a monomer can still occur. Upon release from a mold, there is hardly any driving force for relaxation, so a much better copy of the mold is obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2364–2376, 2003
Computer simulation of the filling process in gas‐assisted injection molding based on gas‐penetration modeling
Authors: Zhou Huamin , Li Dequn
Published: September 2003

Gas‐assisted injection molding can effectively produce parts free of sink marks in thick sections and free of warpage in long plates. This article concerns the numerical simulation of melt flow and gas penetration during the filling stage in gas‐assisted injection molding. By taking the influence of gas penetration on the melt flow as boundary conditions of the melt‐filling region, a hybrid finite‐element/finite‐difference method similar to conventional‐injection molding simulation was used in the gas‐assisted injection molding‐filling simulation. For gas penetration within the gas channel, an analytical formulation of the gas‐penetration thickness ratio was deduced based on the matching asymptotic expansion method. Finally, an experiment was employed to verify this proposed simulation scheme and gas‐penetration model, by comparing the results of the experiment with the simulation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2377–2384, 2003
Effect of mercapto‐modified ethylene–vinyl acetate on the curing parameters and mechanical and dynamic mechanical properties of vulcanized nitrile rubber/ethylene–vinyl acetate blends
Authors: Jansen Paulo , Garcia Filiberto G. , Soares Bluma G.
Published: September 2003

The compatibilizing effect of mercapto‐modified ethylene–vinyl acetate (EVALSH) was investigated in vulcanized nitrile rubber (NBR)/ethylene–vinyl acetate (EVA) copolymer blends. EVALSH increased the ultimate tensile strength, mainly in blends containing larger amounts of NBR. In addition, an accelerating effect of this functionalized copolymer was observed in blends vulcanized with the sulfur system. This behavior was confirmed with oscillating disk rheometry and differential scanning calorimetry analyses. The improvement of the mechanical performance was attributed to the interfacial action associated with the increase in the crosslink density of the NBR phase promoted by the mercapto groups in EVALSH. The effects of EVALSH on the morphology and dynamic mechanical properties were also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2391–2399, 2003
Small‐angle X‐ray scattering from polyethylene: Distorted lamellar structures
Authors: Marega Carla , Marigo Antonio , Causin Valerio
Published: September 2003

Some theoretical models, including lamellar distortions of the second kind, are described. To test the influence of lamellar distortions on the small‐angle X‐ray scattering (SAXS) of polymers, some theoretical patterns were calculated with different values of the model parameters. SAXS diffraction profiles were recorded for three commercial copolymer samples of linear low‐density polyethylene containing different comonomers and one commercial homopolymer sample of high‐density polyethylene; these were successively analyzed by a fit to the calculated profiles corresponding to our theoretical models. Transmission electron microscopy images were obtained of the lamellar morphologies of the four samples. From these, we concluded that the homopolymer sample displayed excellent organization on lamellar stacks, whereas the copolymer samples showed more imperfect lamellar morphologies, so it was useful, in the latter case, to introduce a distorted lamellar structure in calculated SAXS diffraction patterns. By use of wide‐angle X‐ray scattering, we also determined the overall crystallinities of the samples. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2400–2407, 2003
Preparation of O‐carboxymethyl chitosans and their effect on color yield of acid dyes on silk
Authors: Wu Yi Guang , Chan Wing Lai , Szeto Yau Shan
Published: September 2003

O‐Carboxymethyl chitosans with a low degree of substitution (DS) and a high degree of deacetylation (DD) were prepared directly from chitin and characterized by using 1H‐NMR, 13C‐NMR, and elemental analysis methods. In our study, O‐carboxymethyl chitosans could increase the color yield of Acid Red 44 and Acid Green 25 on silk fabrics without lowering the corresponding washing fastness property. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2500–2502, 2003
Ultraviolet curing kinetics of cycloaliphatic epoxide with real‐time fourier transform infrared spectroscopy
Authors: Chen Jianxia , Soucek Mark D.
Published: September 2003

The photo‐induced curing kinetics of cycloaliphatic epoxide coatings were investigated with real‐time Fourier transform infrared spectroscopy with an optical fiber ultraviolet curing system. The consumption of epoxy group as a function of time was obtained by monitoring of the oxirane absorbance in the 789–746‐cm−1 region. The effect of the type of epoxide, hydroxyl equivalent weight, ratio of oxirane to hydroxyl groups (R), photoinitiator, and exposure time on the curing reaction was investigated. In general, the rate of curing was dependent on the hydroxyl equivalent weight, R, type of epoxide, and photoinitiator. For formulations without polyol, both initiator concentration and exposure time had minimal effects on the curing reaction. However, for formulations with polyol, the curing a reaction was dependent on the initiator concentration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2485–2499, 2003
Ion‐plasma modification of polyvinylchloride microfiltration membranes
Authors: Vladkova T. G. , Dineff P. , Stojcheva R. , Tomerova B.
Published: September 2003

Here we present how the surface and some filtration properties of PVC microfiltration membranes are affected by controlled and well‐defined modification by ion‐plasma treatment in the kinetic region of the high voltage (HVGD) or normal glow discharge (NGD) in air. The surface energy and work of adhesion of the samples were calculated from the contact angle with both polar (H2O) and nonpolar (CH2I2) liquid measurement data. The surface morphology was observed by SEM and the surface chemical composition was analyzed by ESCA. The trans‐membrane water flux, the average pore size, and the pore‐size distribution as well as the “bubble point” were used to control the effect of the ion‐plasma treatment on the filtration properties of the PVC microfiltration membranes. Two characteristic regions of the ion‐plasma treatment in air were found in our experiments where the surface properties and filtration characteristics of the membranes are extremely changed: at a pressure of 10–15 Pa in the region of the HVGD and at a pressure of 100–120 Pa in the region of the NGD. It was shown that the ion‐plasma treatment in air is an effective technological method for regulation of some important surface and filtration properties of PVC microfiltration membranes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2433–2440, 2003
DSC analysis of epoxy molding compound with plasma polymer–coated silica fillers
Authors: Roh J. H. , Lee J. H. , Kim N. I. , Kang H. M. , Yoon T.‐H. , Song K. H.
Published: September 2003

Silica fillers were modified by plasma‐polymerization coating of 1,3‐diaminopropane, allylamine, pyrrole, 1,2‐epoxy‐5‐hexene, allylmercaptan, and allylalcohol using RF plasma (13.56 MHz). Modified fillers were then mixed with biphenyl epoxy resin, phenol novolac (curing agent), and optionally triphenylphosphine (catalyst) to prepare samples for DSC analyses. Some samples were also prepared from uncoated silica fillers and monomers used in plasma polymerization coating, instead of plasma polymer–coated silica fillers. Plasma polymer–coated silica fillers were characterized by FTIR, XPS, and water contact angle measurements. In DSC analyses, all samples with plasma polymer–coated silica fillers showed a large peak and an additional one or two small exothermic peaks when catalyst was added, compared to only one large peak with as‐received silica fillers. The large peak could be from epoxy–phenol novolac reaction in the presence of catalyst, whereas small reaction peaks were attributed to the chemical reaction between epoxy resin and functional moieties in the plasma polymer coating, such as amine, OH, and/or SH groups, as evidenced by FTIR and XPS analysis and contact angle measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2508–2516, 2003
Creation of functional materials by use of a slow crystallization process in the nonequilibrium state. I. porous polyamide microparticles
Authors: Asano Yukihiko , Nakayama Kimio , Yao Shigeru
Published: September 2003

Recently a number of investigations have focused on the self‐organization process from the nonequilibrium state as a new technique that may be used to develop many functional materials. In many cases, amorphous polymers were used and semicrystalline polymers were seldom used in spite of their importance. In this study, we basically investigated the crystal structure, crystalline process, and inner structures of polyamide by using slow phase separation and crystallization process from the nonequilibrium state of the polymer solution. We were able to observe the crystalline lamella growing twisted from the center of the particle. Between these lamella layers, narrow pores were created. From this investigation, we developed a new method to create functional materials of polyamide, the semicrystalline polymer. Porous spherical particles may be properly applied to functional materials such as adsorption materials, catalyst support materials, and so on. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2428–2432, 2003
Evaluation of isomeric composition of resol‐type phenol formaldehyde matrix resins for silica–phenolic composites and its effect on cure characteristics of the resin
Authors: Scariah K. J. , Usha K. M. , Narayanaswamy K. , Shanmugam K. , Sastri K. S.
Published: September 2003

The isomeric composition of several samples of resol‐type phenol formaldehyde resins used for silica–phenolic composites was evaluated by 1H‐ and 13C‐NMR spectroscopy and reverse‐phase HPLC techniques. The variations in the isomeric compositions were attributed to inadvertent variations in the process parameters. A mathematical relation was determined for calculation of free phenol from 1H‐NMR measurements. The samples were cured at 160°C for 8 h in an inert atmosphere of N2. The extent of cure in the hardened samples was measured by FTIR analysis. The effect of isomeric composition on the extent of cure was studied. Free phenol and p‐hydroxymethyl phenol, exhibiting a linear correlation, were found to have a pronounced effect on the extent of cure. The cure kinetics were derived by dynamic DSC measurements. Activation energy (E) for curing exhibited a near linear correlation independently with free phenol content and the extent of cure. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2517–2524, 2003
Pervaporation separation of water–isopropanol mixtures using ZSM‐5 zeolite incorporated poly(vinyl alcohol) membranes
Authors: Kittur A. A. , Kariduraganavar M. Y. , Toti U. S. , Ramesh K. , Aminabhavi T. M.
Published: September 2003

A solution technique was employed to prepare ZSM‐5 zeolite incorporated poly(vinyl alcohol) (PVA) membranes for the pervaporation separation of water–isopropanol mixtures. The membranes were characterized by Fourier transform infrared spectroscopy and differential scanning calorimeter. Glass transition temperatures of the membranes varied from 102 to 110°C, with increasing zeolite content of the membrane. The effect of zeolite loading and feed composition on pervaporation performance of the membranes was analyzed. The membrane containing 6 mass % of zeolite gave the highest separation selectivity of 216 for 10 mass % of water containing feed mixture at 30°C. Increase in water selectivity of the membrane was explained as due to a reduction in free volume by increasing zeolite content of the membrane. Separation selectivity and permeation flux data are dependent on water composition of the feed mixture, but are comparatively less dependent on temperature. The hindrance of water permeation at higher composition of water in the feed mixture was explained as due to the formation of clusters of water molecules. The overall activation energy and preexponential factors were calculated using Arrhenius equation. Pervaporation data have also been explained on the basis of thermodynamic parameters calculated by using Arrhenius equation as well as relationship proposed by Ping et al. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2441–2448, 2003
Preparation and characterization of a polyaniline/poly(butyl acrylate–vinyl acetate) composite as a novel conducting polymer composite
Authors: Mirmohseni Abdolreza , Valiegbal K. , Wallace G. G.
Published: September 2003

This is the first report on the preparation and characterization of a polyaniline/poly(butyl acrylate–vinyl acetate) composite. The composite was prepared by the emulsion polymerization of aniline in a medium containing poly(butyl acrylate–vinyl acetate). Films prepared from the composite (cast from an aqueous medium) had excellent mechanical properties and could be stretched up to 900%. The resultant composite was soluble in common organic solvents, and a stable water‐based dispersion could also be prepared. An electrical conductivity of 2.2 S cm−1 was obtained. Cyclic voltammograms revealed that the composite was electroactive. It had excellent adhesion to either glass or steel plate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2525–2531, 2003
Processing and characterization of epoxy–anhydride‐based intercalated nanocomposites
Authors: Torre L. , Frulloni E. , Kenny J. M. , Manferti C. , Camino G.
Published: September 2003

A study of the kinetic and thermal characterization of an epoxy resin (DGEBA) polymerized with a methyl tetrahydrophthalic anhydride reinforced with montmorillonite‐layered silicates is presented. The nanoreinforcement used was compatibilized by exchanging the cations between the silicate layers with alkylammonium salts, containing long hydrocarbon chains. The aim of this study was to develop new nanocomposites based on thermoset resins with improved thermal stability, suitable for electronic applications. Differential scanning calorimetry was used here to produce the polymerization kinetics data, while thermogravimetric analysis was used to evaluate the effects of the nanoreinforcements on the thermal stability and to analyze the degradation kinetics. Unexpected strong effects of the nanocomposite on the polymerization kinetics of the epoxy–anhydride system were detected and evaluated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2532–2539, 2003
Matrix‐assisted laser desorption/ionization mass spectrometry of synthetic polymers. VI. Analysis of phenol–urea–formaldehyde cocondensates
Authors: Schrod M. , Rode K. , Braun D. , Pasch H.
Published: September 2003

Phenolic resoles can be regarded as copolymers of phenol and formaldehyde that are distributed in the chain length and the number of methylol groups per molecule. While other spectroscopic methods like FTIR and NMR only give average structures, MALDI–TOF mass spectrometry is able to resolve the oligomer distribution of phenolic resoles. Using 2,5‐dihydroxybenzoic acid or 2,4,6‐trihydroxyacetophenone as matrices, MALDI–TOF spectra are obtained where each oligomer peak can be assigned to a particular chemical structure. Thus, the degree of polymerization and the number of reactive methylol groups can be determined. For urea‐modified resoles, in addition to phenol–formaldehyde and urea–formaldehyde structures, for the first time, phenol–urea–formaldehyde cocondensate structures can be identified directly. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2540–2548, 2003
Investigation of ethylene and styrene copolymerization initiated with dinuclear constrained geometry catalysts holding polymethylene as a bridging ligand and indenyl as a cyclopentadienyl derivative
Authors: Noh Seok Kyun , Yang Youngdo , Won Seok Lyoo
Published: September 2003

A series of polymethylene‐bridged dinuclear constrained geometry catalysts (CGC) [Me2Si(Ind)(NtBu) TiCl2]2[(CH2)n] (1, n = 6; 2, n = 9; 3, n = 12) were synthesized to study the copolymerization of ethylene and styrene. The experiments display that the polymerization activity of the dinuclear catalysts increased in the order of 1 < 2 < 3, which indicated that the dinuclear CGC with the longest methylene units as a bridge showed the greatest activity. According to the activity correlation with the monomer ratio, all the catalysts exhibited maximum polymerization activity at the monomer ratio of ([styrene]/[ethylene]) of 2. The dinuclear CGC 2 and 3 represented excellent characteristics of styrene reactivity while catalyst 1 represented considerably low styrene reactivity. The relation between the molecular weights of the polymers and the catalysts used in the polymerization is not straightforward. The steric interference in catalyst 1, containing just six methylene bridges, can be applied to explain not only the strikingly decreased activity but also the very low styrene content in the copolymer. In contrast, the electronic effect seems to be more pronounced in manipulating the polymerization properties of catalysts 2 and 3 having nine and 12 methylene bridges, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2469–2474, 2003
Electrochemical preparation of poly(2‐bromoaniline) and poly(aniline‐co‐2‐bromoaniline) in acetonitrile
Authors: Şahin Yücel , Peŗin Sabriye , Şahin Mutlu , Özkan Güleren
Published: September 2003

Electrochemical preparation of poly(2‐bromoaniline) (PBrANI) and poly(aniline‐co‐2‐bromoaniline) [P(An‐co‐2‐BrAn)] was carried out in an acetonitrile solution containing tetrabutylammonium perchlorate (TBAP) and perchloric acid (HClO4). The cyclic voltammograms during the copolymerization had many features similar to those for the usual polymerization of aniline. The copolymer exhibits a higher dry electrical conductivity value than that of PBrANI and a lower one than that of PANI. The observed decrease in the conductivity of the copolymer relative to PANI is attributed to the incorporation of bromine moieties into the polyaniline chain. The structure and properties of the polymer and copolymer were elucidated using cyclic voltammetry (CV), FTIR, and UV‐vis spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2460–2468, 2003
Comparison of ceftibuten transport across Caco‐2 cells and rat jejunum mounted on modified ussing chambers
Authors: Menon R.M. , Barr W.H.
Published: September 2003

Ceftibuten uptake into Caco‐2 cells and intestinal brush border membrane vesicles is mediated by the dipeptide transport system (PEPT1). The apical to basolateral transport characteristics of ceftibuten across Caco‐2 cells and rat jejunum mounted on a modified Ussing chamber was examined. Mannitol was used as a paracellular marker along with trans‐epithelial electrical resistance (TEER) for monitoring tight junction permeability. Transport across Caco‐2 cells and rat jejunum mounted on a modified Ussing chamber was linear across the concentration range 0.25–10 mm. The net flux of mannitol and ceftibuten was higher across rat jejunum compared with Caco‐2 cells. At a donor concentration of 0.25 mm, ceftibuten transport across Caco‐2 cells was found to be pH dependent. Glycyl proline, a dipeptide, and 2,4‐ dinitrophenol, an energy poison, caused a reduction in the permeability of 0.25 mm ceftibuten across Caco‐2 cells. Benzoic acid and adipic acid also inhibited transcellular transport of ceftibuten. At a donor concentration of 0.25 mm, passive paracellular transport accounts for about 60% and the active carrier mediated mechanism accounts for about 40% of ceftibuten transport across Caco‐2 cells. None of the inhibitors however, had a significant effect on ceftibuten transport across rat jejunum mounted on a modified Ussing chamber at a donor concentration of 0.25 mm. In the concentration range 0.25–10 mm, ceftibuten is predominantly transported by paracellular mechanisms across rat jejunum and a mixture of active and passive transport across Caco‐2 cells. Copyright © 2003 John Wiley & Sons, Ltd.
Development of the second‐order derivative UV spectrophotometric method for direct determination of paracetamol in urine intended for biopharmaceutical characterisation of drug products
Authors: Parojčić Jelena , Karljiković‐Rajić Katarina , Durić Zorica , Jovanović Milica , Ibrić Svetlana
Published: September 2003

Paracetamol is a widely used nonsalicylate analgesic and antipyretic drug. The existing methods for the determination of paracetamol in biological fluids are mainly HPLC techniques, although there are some reported methods based on spectrophotometric determinations. However, all these methods involve some extraction or derivatisation procedures. In the present study the UV spectra of investigated samples were recorded over the wavelength range 220–400 nm (λ step 0.21 nm; scan speed 60 nm/min) and second‐order derivative spectra were calculated. Second‐order derivative spectra of different blank urine samples displayed the presence of a zero‐crossing point at 245–247 nm defined as λzc. The zero‐order absorption spectra of paracetamol in water displays maximum absorbance at 243 nm, while in second derivative spectra, a minimum peak at 246 nm was observed. Therefore, the application of zero‐crossing technique to the second‐derivative UV absorption spectrum should be useful for the determination of paracetamol using 2Dλzc.

The proposed method enables determination of total paracetamol in urine directly and simply by reading the 2Dλzc of the diluted samples. The obtained results were in good accordance with published data on cumulative urinary excretion after per oral administration of paracetamol obtained applying different spectrophotometric methods of determination. It could be useful for biopharmaceutical characterisation of drug products (monitoring of the levels of paracetamol in urine in bioavailability testing, for the evaluation of in vitro–in vivo correlation and screening of different formulations during drug product development). Copyright © 2003 John Wiley & Sons, Ltd.
Bioequivalence evaluation of two brands of enalapril 20mg tablets (narapril and renitec) in healthy human volunteers
Authors: Najib Naji M. , Idkaidek Nasir , Adel Ayman , Admour Isra' , Astigarraga Rafel E. B. , Nucci Gliberto De , Alam S. Mahmood , Dham Ruwayda , Qumaruzaman
Published: September 2003

The bioequivalence of two brands of enalapril 20 mg tablets was demonstrated in 24 healthy human volunteers after a single oral dose in a randomized cross‐over study, conducted at IPRC, Amman, Jordan. Reference (Renitec, MSD, Netherlands) and test (Narapril, Julphar, UAE) products were administered to fasted male volunteers; blood samples were collected at specified time intervals, plasma separated and analysed for enalapril and its active metabolite (enalaprilat) using a validated LC‐MS/MS method at Cartesius Analytical Unit, Institute of Biomedical Sciences, USP, Sao Paulo, Brazil. The pharmacokinetic parameters AUC0−t, AUC0−∝, Cmax,Tmax,T1/2 and elimination rate constant were determined from plasma concentration‐time profile for both formulations and were compared statistically to evaluate bioequivalence between the two brands, using the statistical modules recommended by FDA. The analysis of variance (ANOVA) did not show any significant difference between the two formulations and 90% confidence intervals fell within the acceptable range for bioequivalence. Based on these statistical inferences it was concluded that the two brands exhibited comparable pharmacokinetic profiles and that Julphar's Narapril is bioequivalent to Renitec of MSD, Netherlands. Copyright © 2003 John Wiley & Sons, Ltd.
Nucleic Acid Aptamers as Tools and Drugs: Recent Developments
Authors: Rimmele Martina
Published: September 2003

Nucleic acid aptamers are molecules that bind to their ligands with high affinity and specificity. Unlike other functional nucleic acids such as antisense oligonucleotides, ribozymes, or siRNAs, aptamers almost never exert their effects on the genetic level. They manipulate their target molecules such as gene products or epitopes directly and site specifically, leaving nontargeted protein functions intact. In a similar way to antibodies, aptamers bind to many different kinds of target molecules with high specificity and can be made to order, but as a result of their different biochemical nature and size they can also be used complementary to antibodies. In some cases, aptamers might be more suitable or more specific than antibody approaches or small molecules, both as scientific and biotechnological tools and as therapeutic agents. Recent examples of characterization of aptamers as tools for scientific research to study regulatory circuits, as tools in diagnostic or biosensor development, and as therapeutic agents are discussed.
Antisense Inhibition of Escherichia coli RNase P RNA: Mechanistic Aspects
Authors: Gruegelsiepe Heike , Willkomm Dagmar K. , Goudinakis Olga , Hartmann Roland K.
Published: September 2003

The ribonucleoprotein enzyme RNase P catalyzes endonucleolytic 5′‐maturation of tRNA primary transcripts in all domains of life. The indispensability of RNase P for bacterial cell growth and the large differences in structure and function between bacterial and eukaryotic RNase P enzymes comply with the basic requirements for a bacterial enzyme to be suitable as a potential novel drug target. We have identified RNA oligonucleotides that start to show an inhibitory effect on bacterial RNase P RNAs of the structural type A (for example, the Escherichia coli or Klebsiella pneumoniae enzymes) at subnanomolar concentrations in our in vitro precursor tRNA (ptRNA) processing assay. These oligonucleotides are directed against the so‐called P15 loop region of RNase P RNA known to interact with the 3′‐CCA portion of ptRNA substrates. Lead probing experiments demonstrate that a complementary RNA or DNA 14‐mer fully invades the P15 loop region and thereby disrupts local structure in the catalytic core of RNase P RNA. Binding of the RNA 14‐mer is essentially irreversible because of a very low dissociation rate. The association rate of this oligonucleotide is on the order of 104 M−1 s−1 and is thus comparable to those of many other artificial antisense oligonucleotides. The remarkable inhibition efficacy is attributable to the dual effect of direct interference with substrate binding to the RNase P RNA active site and induction of misfolding of the catalytic core of RNase P RNA. Based on our findings, the P15 loop region of bacterial RNase P RNAs of the structural type A can be considered the “Achilles' heel” of the ribozyme and therefore represents a promising target for combatting multiresistant bacterial pathogens.
Heterogeneous trading agents
Authors: Neuberg Luc , Bertels Koen
Published: September 2003

In this article, we present a multiagent system (MAS) simulation of a financial market and investigate the requirements to obtain realistic data. The model consists of autonomous, interactive agents that buy stock on a financial market. Transaction decisions are based on a number of individual and collective elements, the former being risk aversion and a set of decision rules reflecting their anticipation of the future evolution of prices and dividends and the latter the information arriving on the market influencing the decision making process of each trader. We specifically look at this process and the following observations hold: The market behavior is determined by the information arriving at the market and agent heterogeneity is required in order to obtain the right statistical properties of the price and return time series. The observed results are not sensitive to changes in the parameter values. © 2003 Wiley Periodicals, Inc.
The effect of different components of psychological therapy on people with delusions: five experimental single cases
Authors: Jakes Simon C. , Rhodes John E.
Published: September 2003

This study is a contribution to the investigation of the active ingredient in psychological therapy for psychosis. Five people with chronic delusions were treated using a single‐case experiment design. The treatment was broken down into components that were administered sequentially. A baseline phase was followed by three different treatment conditions (An A–B–C–D design). The treatments were (1) Solution‐focused Therapy (2) Schema‐focused cognitive therapy (3) Cognitive therapy focused on modification of the delusion. Three of the five clients responded to treatment with a large change in degree of belief in their delusion. Two clients improved during solution‐focused therapy, one client improved during cognitive challenging of the delusion and one client changed during baseline. The implications of this study are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Tattooing as a means of acute affect regulation
Authors: Anderson Michael , Sansone Randy A.
Published: September 2003

In this report, we describe the case of a 19‐year‐old male who acutely used the process of tattooing, and its associated physical pain, to regulate negative affective states. While tattooing has been described in the literature as serving individuals in a variety of ways (e.g. establishing a sense of individuality, externalizing important feelings), we are unaware of any prior case reports describing this affective function. Indeed, in this case, tattooing may have functioned more like self‐harm behaviour, and we discuss this potential implication. Copyright © 2003 John Wiley & Sons, Ltd.