bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraputamenal infusion of GDNF in aged rhesus monkeys: Distribution and dopaminergic effects
Authors: Ai Yi , Markesbery William , Zhang Zhiming , Grondin Richard , Elseberry Dennis , Gerhardt Greg A. , Gash Don M.
Published: April 2003

Site‐specific delivery of trophic factors in the brain may be important for achieving therapeutic efficacy without unwanted side effects. This study evaluated the site‐specific infusion of glial cell line–derived neurotrophic factor (GDNF) into the right putamen of aged rhesus monkeys. After 4 weeks of continuous infusion at a rate of 22.5 μg/day, GDNF had diffused up to 11 mm from the catheter openings in the putamen into the rostral putamen, internal capsule, external capsule, caudate nucleus, and globus pallidus. Anisotropic flow along the external capsule tracts carried GDNF into the anterior amygdaloid area. Backflow of GDNF along the catheter track from the frontal cortex infiltrated juxtaposed corpus callosal and cortical tissue. GDNF was carried by retrograde transport to dopamine neurons in the ipsilateral substantia nigra, stimulating an 18% increase in the number of tyrosine hydroxylase (TH)–positive dopamine neurons and a 28% increase in dopamine neuron perikaryal size. Also, TH‐positive fiber density was increased in the ipsilateral globus pallidus, caudate nucleus, and putamen. Anatomic effects from GDNF stimulation of the dopaminergic system were restricted to the ipsilateral hemisphere. Retrograde GDNF labeling was also present in a few TH‐positive neurons in the locus coeruleus and a large cluster of TH‐negative neurons in the ventral anterior thalamus. Anterograde transport of GDNF was evident in axons in the pyramidal tract from the cerebral peduncle to the caudal spinal cord. Tissue injury from the intraparenchymal catheter and continuous infusion was confined primarily to a narrow zone surrounding the track and was mild to moderate in severity. J. Comp. Neurol. 461:250–261, 2003. © 2003 Wiley‐Liss, Inc.
Chronic nerve compression induces concurrent apoptosis and proliferation of Schwann cells
Authors: Gupta Ranjan , Steward Oswald
Published: April 2003

Chronic nerve compression (CNC), as in carpal tunnel syndrome, is a common cause of peripheral nerve dysfunction in humans. Previous studies using animal models have demonstrated progressive demyelination and a slowing of nerve conduction velocity. To characterize the Schwann cell response to CNC, we evaluated total Schwann cell number, apoptosis, and proliferation in an animal model of CNC. Design‐based stereologic techniques revealed a striking transient increase in Schwann cell number following CNC. Schwann cell number increased sixfold relative to the normal nerve at the site of compression at 1 month and then slowly declined toward control levels. Nevertheless, assays of apoptosis (TUNEL and an antipoly‐ADP‐ribose polymerase labeling assays) revealed extensive Schwann cell apoptosis at 2 weeks postcompression, which is during the time when Schwann cell number was increasing. Electron microscopic analysis confirmed that these dramatic changes in Schwann cells occurred in the absence of axon degeneration and axonal swelling and before there were any detectable alterations in nerve conduction velocity. Counts of bromodeoxyuridine‐labeled Schwann cells revealed that proliferation occurred concurrently with ongoing apoptosis. To define further the possible mitogenic properties of mechanical stimuli on Schwann cells, we used an in‐vitro model to deliver shear stress in the form of laminar fluid flow to pure populations of Schwann cells and confirmed that mechanical stimuli induce Schwann cell proliferation. Our findings indicate that chronic nerve compression induces Schwann cell turnover with minimal axonal injury and support the idea that mechanical stimuli have a direct mitogenic effect on Schwann cells. J. Comp. Neurol. 461:174–186, 2003. © 2003 Wiley‐Liss, Inc.
Increased expression of multiple neurofilament mRNAs during regeneration of vertebrate central nervous system axons
Authors: Gervasi Christine , Thyagarajan Amar , Szaro Ben G.
Published: April 2003

Characteristic changes in the expression of neuronal intermediate filaments (nIFs), an abundant cytoskeletal component of vertebrate axons, accompany successful axon regeneration. In mammalian regenerating PNS, expression of nIFs that are characteristic of mature neurons becomes suppressed throughout regeneration, whereas that of peripherin, which is abundant in developing axons, increases. Comparable changes are absent from mammalian injured CNS; but in goldfish and lamprey CNS, expression of several nIFs increases during axon regrowth. To obtain a broader view of the nIF response of successfully regenerating vertebrate CNS, in situ hybridization and video densitometry were used to track multiple nIF mRNAs during optic axon regeneration in Xenopus laevis. As in other successfully regenerating systems, peripherin expression increased rapidly after injury and expression of those nIFs characteristic of mature retinal ganglion cells decreased. Unlike the decrease in nIF mRNAs of regenerating PNS, that of Xenopus retinal ganglion cells was transient, with most nIF mRNAs increasing above normal during axon regrowth. At the peak of regeneration, increases in each nIF mRNA resulted in a doubling of the total amount of nIF mRNA, as well as a shift in the relative proportions contributed by each nIF. The relative proportions of peripherin and NF‐M increased above normal, whereas proportions of xefiltin and NF‐L decreased and that of XNIF remained the same. The increases in peripherin and NF‐M mRNAs were accompanied by increases in protein. These results are consistent with the hypothesis that successful axon regeneration involves changes in nIF subunit composition conducive to growth and argue that a successful injury response differs between CNS and PNS. J. Comp. Neurol. 461:262–275, 2003. © 2003 Wiley‐Liss, Inc.
Error analysis and Hertz vector approach for an electromagnetic interaction between a line current and a conducting plate
Authors: Attaf M.T.
Published: April 2003

In the present paper we first introduce the Hertz vector potential and examine how the specific case of electromagnetic field diffusion problems can be formulated in terms of this potential. Its connection to other commonly used potentials is presented and a basic approach in the form of a suitable set of equations is introduced. The suggested method is then successfully applied to solve the case of an electromagnetic interaction between a straight conductor carrying sinusoidal current and a finite thickness fixed plate. Due to the oscillatory aspect of the integral solution obtained, an appropriate numerical treatment is investigated and various curves are shown to illustrate the convergence behaviour. Copyright © 2003 John Wiley & Sons, Ltd.
Generalized non‐uniform transmission‐line models for local radiation from microstrip bends in MMICs
Authors: Liu Y. W. , Zhao D. S. , Mei K. K.
Published: April 2003

Although microstrip bends in high‐speed digital MMICs have been widely investigated for the past two decades, their local radiation characteristics rather than their reflection characteristics have not been completely explored yet. In this paper, the generalized non‐uniform transmission‐line equations are used in analysing the microstrip bends including their local radiations. In our new models, the whole structure of a bend is regarded as a non‐uniform transmission line that is totally governed by the generalized non‐uniform transmission‐line equations. Except for analytical simplification and broad bandwidth performance, the new analysis could indicate where the strongly local radiations along a bend structure come from. Copyright © 2003 John Wiley & Sons, Ltd.
TLM simulation of microwave hybrid sintering of multiple samples in a multimode cavity
Authors: Amri A. , Saidane A.
Published: April 2003

Microwave heating technology is a powerful mean to ensure successful sintering of ceramic materials. In sintering experiments, low loss insulators, conductors and high‐loss ceramics are microwaved so as to get optimal mechanical and structural properties. It is known that low‐loss ceramic materials such alumina and zirconia exhibit long waiting time before reaching a critical coupling temperature at which microwaves can be readily absorbed. On the other hand, some ceramics such as silicon carbid have a high loss factor and therefore can be used as a process stimulus for microwave sintering of microwave transparent ceramics. Furthermore, successful sintering experiments often require the use of carefully designed insulating structure in order to minimize thermal gradients caused by heat loss from surfaces. All these problems have led to the introduction of microwave hybrid heating (MHH) schemes using higher dielectric loss susceptors, insulation or coating. Since MHH depend mainly on human expertise, the optimization of sintering experiments will certainly benefit from numerical simulations. The transmission line matrix (TLM) is used to study two MHH schemes where both a susceptor and an insulating matrix were, respectively, used as process stimulus for microwave heating of multiple alumina samples within a three‐dimensional multimode cavity. The effects of such MHH schemes and target settings on electric field distribution and power absorption rates are reported in this paper. Copyright © 2003 John Wiley & Sons, Ltd.
Accurate extrapolation to zero cell size by Padé approximation
Authors: Ingelström Pär , Lindholm Love , Rylander Thomas
Published: April 2003

It is shown that extrapolation to zero cell size can be made accurately by means of Padé approximation. The extrapolation procedure is tested on waveguide cavity filters analysed by the finite difference‐time domain (FDTD) scheme. Extrapolation by the traditional Taylor series can yield unphysical results in the vicinity of resonances where it is outperformed by extrapolation based on the Padé approximation. Direct computation with the FDTD scheme (without extrapolation) requires extreme and infeasible resolutions to achieve a reasonable accuracy close to resonances. Copyright © 2003 John Wiley & Sons, Ltd.
On the Laplace operator and on the vector potential problems in the half‐space: an approach using weighted spaces
Authors: Boulmezaoud Tahar Zamène
Published: April 2003

The purpose of the present paper is twofold. The first object is to study the Laplace equation with inhomogeneous Dirichlet and Neumann boundary conditions in the half‐space of ℝN. The behaviour of solutions at infinity is described by means of a family of weighted Sobolev spaces. A class of existence, uniqueness and regularity results are obtained. The second purpose is to investigate some properties of grad, div and curl operators in order to treat curl–div systems of the form

curl w = u, div w = 0

and problems related to vector potentials and Helmholtz decomposition.Copyright © 2003 John Wiley & Sons, Ltd.
Global behaviour of 1‐D viscous compressible barotropic flows with free boundary and self‐gravitation
Authors: Zlotnik Alexander
Published: April 2003

We consider an initial–boundary value problem for a system of quasilinear equations for one‐dimensional flows of a viscous compressible barotropic fluid with large data. An outer pressure (possibly zero) is prescribed on one of the boundaries; also a self‐gravitation is taken into account. The case of the stationary pressure with possible degeneration is studied. For a general non‐monotone state function, either global estimates for the solution and its stabilization are proved or the growth of the fluid volume is bounded from below as t → ∞. For the power state function, in addition, stabilization rate estimates (of the power type) are given. The study is accomplished in the Lagrangian mass co‐ordinates. Copyright © 2003 John Wiley & Sons, Ltd.
Anionic living polymerization of tert‐Aminostyrenes and application of the polymers
Authors: Se Kazunori
Published: April 2003

Anionic living polymerization of tertiary aminostyrenes (tAS) that serve as chemical links between two polymers are studied and the applications of the polymers to reversible recording materials are summarized in this paper. For preparing well‐defined polymers that have desired molecular weights and narrow molecular weight distributions by anionic living mechanism, three conditions are satisfied and the corresponding five experimental proofs are discussed using tAS as an example. The three poly(tertiary aminostyrene)s (PtAS) were prepared. The degree of quaternization of PtAS with n‐butyl bromide could be controlled from 0 to 100%. The amino groups of PtAS were quaternized by p, p′‐bis(chloromethyl)azobenzene (CAB) to prepare the cross‐linked film and the network concentration was characterized by an equilibrium‐swelling test. Photochemical isomerization of CAB incorporated in PtAS was investigated in order to prepare the reversible recording materials. Copyright © 2003 John Wiley & Sons, Ltd.
The biodegradation of poly(3‐hydroxy‐butyrate‐co‐3‐hydroxyvalerate) (PHB/V) and PHB/V‐degrading microorganisms in soil
Authors: Song Cunjiang , Wang Shufang , Ono Shin , Zhang Banghua , Shimasaki Choichiro , Inoue Masami
Published: April 2003

To assess the polyhydroxyalkanoate (PHA)‐biodegrading capacity of soil, numbers of aerobic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHB/V)‐degrading microorganisms (degraders) were estimated by the film‐MPN method. The numbers of PHB/V degraders were estimated to be 4.3 × 105 per gram of dry garden soil, 5.06 × 105 per gram of dry paddy‐field soil, and 3.87 × 105 per gram of dry river‐bank soil. The degradations of PHB/V in suspensions of the three kinds of soil were investigated. It was found that the PHB/V‐biodegrading capacity of the soil increased as the number of PHB/V degraders in the soil increased. The relationship between weight loss of PHB/V and proliferation rate of PHB/V degraders in garden soil suspension was investigated. The effect of glucose on the biodegradation of PHB/V in garden soil was also studied. The weight loss after one week in garden soil suspension supplemented with 20 mM of glucose (GSS‐20G) was 2.60%, which was lower than that in garden soil suspension (GSS) (7.14%). After five weeks, the weight loss had increased to 24.97% in GSS‐20G but only to 18.26% in GSS. The results showed that glucose played important roles in inhibition and acceleration of different biodegrading phases and finally accelerated the PHB/V biodegradation in soil suspension. Copyright © 2003 John Wiley & Sons, Ltd.
Preparation of IPN‐type stimuli‐Responsive heavy‐Metal‐Ion adsorbent gel
Authors: Yamashita Keiji , Nishimura Takashi , Nango Mamoru
Published: April 2003

We apply the interpenetration network (IPN) gel of poly(N‐isopropylacrylamide) (PNIPAm) and poly(sodium acrylate) (PNaAAc) to the stimuli‐responsive heavy‐metal‐ion adsorbent system. In the IPN gel system, PNIPAm and PNaAAc units are expected to behave independently. Therefore, the IPN gel of PNIPAm exhibits a thermosensitive volume–phase transition behavior in spite of the presence of polyelectrolytes like PNaAAc that are well known to prevent PNIPAm from shrinking when above their lower critical solution temperature (LCST). NIPAm‐co‐NaAAc copolymer gel (copoly gel) absorbed water and adsorbed Cu(II) ions sufficiently but did not exhibit the volume–phase transition behavior at all in the Cu(II) ion adsorption‐condition. On the other hand, the IPN gel consisting of PNIPAm and PNaAAc exhibited the volume–phase transition behavior in the adsorbtion‐condition. That is, the IPN gel adsorbed Cu(II) ion sufficiently below its LCST but not above the LCST. We could thermally control the adsorption abilities for heavy‐metal ions by using the IPN gel system. The swelling IPN gel, which adsorbed Cu(II) ions, suddenly shrank when the temperature rose above the LCST. The IPN gel released water but did not release heavy‐metal ions when shrinking. We are planning to construct an easy‐recovery system for heavy‐metal ions from wastewater by using this stimuli‐responsive IPN gel. That is, we quickly adsorb the heavy metal ions from wastewater by using our swelling IPN gel below the LCST, and then squeeze the swelling IPN gel, which has bound the heavy metal ions, by raising the temperature above the LCST in order to facilitate ion handling. Finally, we can remove the heavy metal ions by means of acidic‐treatment of the IPN gel and recycle the IPN gel‐adsorbent. Copyright © 2003 John Wiley & Sons, Ltd.
Ionic conducting polymer encapsulated graphite as the anode material for lithium ion batteries
Authors: Pan Qinmin , Wang Lingzhi , Fang Shibi
Published: April 2003

A novel surface modification approach involving the application of radiation technology to the development of graphite anode of lithium ion batteries. Ionic conductive poly(stylene sulfonic acid) lithium salt (PSSALi) was microencapsulated on the surface of graphite particles by means of radiation‐initiated polymerization. Results showed that the cointercalation of solvated Li+ in a propylene carbonate (PC) based electrolyte was depressed successfully and the initial coulombic efficiency was enhanced after encapsulation. The high stability of the surface structure of encapsulated graphite during the initial intercalation process was observed by in situ Raman spectroscopy. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis of comb graft copolymersI–Ring‐opening metathesis polymerization of norbornyl‐polymethacrylate by a supported ruthenium carbene complex generated in situ
Authors: Li Hong , Zhang Wenfang , Wang Yuqin , Binglin He
Published: April 2003

The Diels–Alder reaction of cyclopentadiene (CPD) and allyl chloride (AC) was carried out by using BF3·Et2O or its supported counterpart on tailor‐made polystyrene supports as catalysts. The activity of the latter is double that of the former, and the yield of the product 5‐chloromethyl‐2‐norbornene (NBCH2Cl) reached up to 67.4%. Then, via living anionic polymerization, a cycloolefinyl macromonomer, 5‐PMMA‐2‐norbornene (NB‐PMMA), was synthesized using NBCH2Li as the initiator which in turn was prepared by a lithiation reaction of NBCH2Cl in THF. Comb‐shaped graft copolymer PNB‐g‐PMMA was finally synthesized via ring‐opening metathesis polymerization (ROMP) of the synthesized macromonomer NB‐PMMA under the catalysis of a polymer‐supported ruthenium carbene complex generated in situ. The polymer‐supported carbene species shows much better initiation behavior than its unsupported counterpart. In both cases, that is in the Diels–Alder reaction and ROMP, the effect mechanism of the tailored supports of the catalysts is discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Influence of core–Shell structured particles on the impact resistance of poly(vinyl chloride)
Authors: Guo Tian‐Ying , Tang Guang‐Liang , Hao Guang‐Jie , Wang Shu‐Fang , Song Moud‐Dao , Zhang Bang‐Hua
Published: April 2003

The core–shell structured particles which comprise rubbery and glassy layers were prepared by emulsifier‐free emulsion polymerization of poly(n‐butyl acrylate/methyl methacrylate)/poly(methyl methacrylate/n‐butyl acrylate) [P(BA/MMA)/P(MMA/BA)]. The core–shell structured particle toughened PVC blends were investigated in detail. Impact strength, elongation at break and the related mechanical properties were measured for further evaluation of the toughening efficiency. Copyright © 2003 John Wiley & Sons, Ltd.
Morphology and levonorgestrel release behavior of polycaprolactone/ poly(ethylene oxide)/Polylactide tri‐component copolymeric microspheres
Authors: Li Guangming , Cai Qing , Bei Jianzhong , Wang Shenguo
Published: April 2003

A novel polycaprolactone/poly(ethylene oxide)/polylactide (PCEL) tri‐component copolymer was synthesized and used for the investigation of lipid‐soluble drug levonorgestrel (LNG), in vitro release from drug‐loaded microspheres. The hydrophilicity of the PCEL strongly depended on the content of the poly(ethylene oxide) (PEO) segment. LNG‐loaded biodegradable polylactide (PLA) and PCEL microspheres have been successfully prepared by using an oil‐in‐water emulsion and solvent‐evaporation method. The effect of various factors such as chemical composition and molecular weight on the morphology of the microspheres produced has been investigated. The influence of chemical composition and hydrophilicity on the drug‐loading efficiency has also been investigated. The release behaviors of LNG in vitro from the PLA and PCEL microspheres were determined. The drug‐loading efficiency and LNG‐release behavior closely depended on the chemical composition and morphology of the polymeric microspheres. With the addition of a PEO segment in the copolymer chains, the structure of the microspheres became porous which would lower the drug‐loading efficiency and speed up the drug‐release rate. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis, characterization and properties of azobenzene side‐chain polythiophene
Authors: Gan Leong Huat , Xia Xulin , Chan Chee Yun , Hu Xiao , Zhao Xiongyan
Published: April 2003

Thiophene monomers with an azobenzene moiety of different spacer length at the 3‐position of the thiophene ring were synthesized. The monomers were polymerized and copolymerized with 3‐hexyl thiophene to investigate the influence of an azobenzene side‐chain on the properties of polythiophene, which has been widely used as a conducting polymer and has also been found many other applications. The polymers were characterized with UV‐vis, FT‐IR spectrophotometry, gel permeation chromatographic (GPC) analysis, DSC, TGA, elemental analysis and X‐ray diffractometry. The polymers showed novel thermochromic and photoresponsive properties in polymer solutions and solid films. It was found that an azobenzene side‐chain could bring about substantial thermochromic and photochromic changes to the polythiophene backbone as compared with non‐azobenzene side‐chain polythiophenes. These property changes could be triggered or controlled by light or heat on the basis of azobenzene trans–cis or cis–trans isomerization. Copyright © 2003 John Wiley & Sons, Ltd.
Hydrogenation of carboxylic acids catalyzed by magnesia‐supported poly‐γ‐aminopropylsiloxane–Ru complex
Authors: Mao Bao‐Wei , Cai Zhong‐Zhan , Huang Mei‐Yu , Jiang Ying‐Yan
Published: April 2003

Magnesia‐supported poly‐γ‐aminopropylsiloxane–ruthenium complex catalysts (MgO‐NH2‐Ru) have been prepared by a very simple method and have been found to be capable of catalyzing the hydrogenation of some simple carboxylic acids, such as acetic acid, propionic acid, lactic acid and isobutyric acid to give ethanol, propanol, 1,2‐propanediol and isobutyl alcohol in 100% yields respectively in the presence of water at 240 °C and under 5.0 × 106 Pa H2 for 18 h. The catalyst was very stable and could be used repeatedly without any noticeable changes in its catalytic activity. Copyright © 2003 John Wiley & Sons, Ltd.
Intra‐ and intermolecular charge‐transfer phenomena in a triphenylamine‐containing anthrylenevinylene‐based copolymer and its model compound
Authors: Zheng Min , Bai Fenglian , Zhu Daoben
Published: April 2003

Optical properties of a triphenylamine‐containing anthrylenevinylene‐based copolymer and its model compound were evaluated using absorption and steady‐state fluorescence spectroscopy. The polymer and model compound show a strong solvatochromic shift as a function of solvent polarity, indicating the emission of an additional charge‐transfer species. More direct and convincing evidences of the charge transfer, such as temperature and concentration‐dependent emission, are presented. Low temperature (77 K) fluorescence also confirmed the existence of charge transfer. Additionally, a twisted intramolecular charge transfer state was observed in the model compound when excited by higher energy, which could not be observed in the polymer whatever the excitation was. The results indicate that there are more charge transfer states including intramolecular, intermolecular and interchain charge transfer states in polymers than in the model compound. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis, characterization and Cis–Trans photoisomerization of a series of hyperbranched conjugated polymers
Authors: He Qingguo , Yang Junlin , Lin Hongzhen , Zhang Lin , Song Yan , Bai Fenglian
Published: April 2003

A series of hyperbranched polyphenylene vinylenes (HPVs) with different alkoxy substituted end groups were synthesized and characterized. The photoluminescence properties were investigated, and the cis–trans isomerization was found by prolonging the exposure time to UV light for the HPVs. The viscosity and end‐group effects on the photoisomerization were studied. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and photophysical properties of alternating copolymers containing triphenylamine moieties
Authors: Huang Hongmin , He Qingguo , Song Yan , Lin Hongzhen , Yang Junlin , Bai Fenglian
Published: April 2003

Two alternating copolymers containing triphenylamine and biphenyl or fluorene, poly[triphenylamine‐alt‐biphenylene vinylene] (TPA‐PBPV) and poly[triphenylamine‐alt‐2,7‐fluorenenylene vinylene] (TPA‐FLV) were synthesized by means of the Wittig reaction. Both the polymers show good solubility in common organic solvents and excellent film‐forming ability. Thermogravimetric analysis investigation demonstrates that the polymers have high thermal stability, the degradation temperature of TPA‐FLV is as high as 499.0 °C. Differential scanning calorimetry results indicate that the glass transition temperature of poly TPA‐FLV is higher than 200 °C, much higher than that of PBPV‐TPA, which might be a merit for the long‐life operation of light‐emitting devices. The photophysical properties of the polymers were investigated in both CH2Cl2 solution and spin‐coated film, photoluminescence efficiencies are also determined, PFV‐TPA has a higher efficiency, which may make it a more promising candidate for light‐emitting materials. Copyright © 2003 John Wiley & Sons, Ltd.
Tubular poly(ortho‐toluidine) synthesized by a template‐free method
Authors: Wan Meixiang , Li Junchao
Published: April 2003

Microtubules of poly(ortho‐toluidine) (POT), with 0.8–6.0 µm diameter and 10−4–10−2 S/cm room‐temperature conductivity, were synthesized by a template‐free method in the presence of β‐naphthalene sulfonic acid (β‐NSA) as a dopant. It was found that the completeness, size, room‐temperature conductivity and crystallinity of the resulting POT‐NSA microtubules depended upon the concentration of the NSA dopant. UV‐vis. spectra, XPS and X‐ray diffraction were used to characterize the molecular structure, showing that the polymer chain of POT‐NSA microtubules is identical to that of the doped POT synthesized by a common method, but that its crystallinity is higher than that of common POT. It was proposed that the monomer salt formed with NSA played a template‐like role in forming POT‐NSA microtubules. Copyright © 2003 John Wiley & Sons, Ltd.
Self‐assembled hyperbranched poly(para‐Phenylene vinylene) monolayers: fabrication and characterization
Authors: Wang Wenlong , He Qingguo , Zhai Jin , Yang Junlin , Bai Fenglian
Published: April 2003

Covalently‐bound self‐assembled monolayer of a kind of functional hyperbranched polymer, pyridine‐capped hyperbranched poly(para‐phenylene vinylene) (Py‐HPV), was prepared on hydrophilic quartz or single‐crystal silicon substrates using siloxane self‐assembly techniques. The assembling procedure was characterized by contact angle measurement, X‐ray photoelectron spectroscopy (XPS), UV‐vis spectra and fluorescence spectroscopy. Atomic force microscopy (AFM) was also used to investigate the surface morphology and microstructure of the resulting Py‐HPV self‐assembled monolayer. Copyright © 2003 John Wiley & Sons, Ltd.
Peroxidation of benzaldehyde catalyzed by cobalt(II)‐chelated copolymer
Authors: Wang Cheng‐Chien , Chen Hui‐Chun , Bin Hsueh‐Huai , Chen Chuh‐Yung
Published: April 2003

A cobalt(II)‐chelated copolymer was prepared through copolymerization of styrene, acrylonitrile (AN), and divinyl benzene with glycidyl methacrylate (GMA)‐iminodiacetic acid (IDA) chelating monomers. Based on the experimental results of FTIR and EA, iminodiacetic acid was grafted on to the side chain of copolymer support. IDA contained in these copolymers was 22.67 wt%. BET was employed to measure the 0.7136 m2/g surface area, which provided the reaction sites for the reactants and active groups of the polymeric support. Additionally, the peroxidation of benzaldhyde with cobalt(II)‐chelated copolymer was investigated. After 3 h, the perbenzoic acid yield increased to 82%. As well, the high yield and perbenzoic acid selectivity were 68.9% and 69%, respectively. More cobalt(II)‐chelated copolymer used to catalyse peroxidation of benzaldehyde, the reaction rate was higher but the selectivity was decreased slightly in high conversion. Lower reaction temperature could moderate the characteristics of peroxidation for high conversion combined with low selectivity of perbenzoic acid. The perbenzoic acid content would decrease slightly owing to the presence of highly hydrophilic cobalt(II)‐chelated copolymer, prepared when the oxidation reaction reached high conversion. Furthermore, the perbenzoic acid product was stable and not decomposed by this cobalt(II)‐chelated copolymer. A moderate amount of water had a co‐activing effect on the cobalt(II)‐chelated copolymer. Copyright © 2003 John Wiley & Sons, Ltd.
Hydrogenation of nitrobenzene, cyclohexanone and octene catalyzed by silica‐supported starch‐L‐Glutamic acid–Fe complex
Authors: Liu Hong‐Wen , Huang Kai , Mi Ji‐Dong , Jia Yi , Huang Mei‐Yu , Jiang Ying‐Yan
Published: April 2003

A new polymer‐base metal complex, silica‐supported starch‐L‐glutamic acid–Fe complex (SiO2‐ST‐Glu‐Fe) has been prepared by a simple method. Starch was reacted with L‐glutamic acid in the presence of silica to give a ligand SiO2‐ST‐Glu, then this was reacted with FeCl3·6H2O to form the Fe complex (SiO2‐ST‐Glu‐Fe). The complex has been found to be able to catalyze the hydrogenation of nitrobenzene to give aniline in 100% yield, cyclohexanone to give cyclohexanol in 93% yield and octene to give octane in 84% yield at 45 °C and under atmospheric pressure. Experimental data show that the catalyst was very stable and could be reused without any noticeable change in its catalytic activity. Copyright © 2003 John Wiley & Sons, Ltd.
Friedel‐Crafts acylation of benzene derivatives catalyzed by silica and alumina‐supported polytrifluoromethanesulfosiloxane
Authors: Zhou Da‐Qing , Zhang Yan‐Hong , Huang Mei‐Yu , Jiang Ying‐Yan
Published: April 2003

Inorganic polymer, silica and alumina‐supported polytrifluoromethanesulfosiloxane solid superacids (abbreviated as SiO2‐Si‐SCF3 and Al2O3‐Si‐SCF3), have been prepared. The acid strength of superacids is higher than that of 100% H2SO4. It was found that SiO2‐Si‐SCF3 and Al2O3‐Si‐SCF3 could catalyze Friedel–Crafts acylation of benzene and benzene derivatives with aroyl chlorides under relatively mild conditions. The yield could amount to 97.6% and 92.1% respectively. The yield and the isomer distribution of corresponding ketones were influenced by reaction temperature and reaction time. The catalysts have considerably high stability and can be reused repeatedly without any large changes in their catalytic activity. The reactions are very clean, with HCl as the only by‐product escaping during the reaction. Copyright © 2003 John Wiley & Sons, Ltd.
Design, synthesis and characterization of semi‐conducting interpenetrating polymer network (IPN) of pyridine and poly(antimony acrylate)
Authors: Kamal Meet , Srivastava A K
Published: April 2003

A new series of semi‐conducting interpenetrating polymer networks (IPNs) based on pyridine and poly(antimony acrylate) were synthesized. Structural evidence for IPNs come from the infrared spectra indicating characteristic frequencies of (>C = O) of poly(antimony acrylate) at 1680 cm−1. Properties such as percentage swelling, average molecular weight between crosslinks (Mc) and Young's modulus are direct functions of the concentration of linear polymer and initiator (benzoyl peroxide), whereas inverse relationships with concentration of monomer (pyridine) and crosslinker (divinyl benzene) are observed. The presence of antimony in the IPNs is determined by SEM and elementac analysis. The DSC curve shows two glass transition temperatures (Tg), at 110 and 150 °C. The IPNs formed with a low content of pyridine exhibited processability, mechanical properties and conductivity.

© 2003 Society of Chemical Industry
Analysis of the tensile modulus of poly(p‐hydroxybenzoate)/poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) ternary polyester composite fibers
Authors: Lee Seung Goo , Kim Seong Hun
Published: April 2003

Liquid crystalline polymer reinforced plastics were prepared by compounding (PHB/PEN/PET) blends. A fibrillar PHB structure was formed in situ in the PEN/PET matrix under a high elongational flow field during melt‐spinning of the composite fibers. The formation of PHB microfibrils in the composite fiber with different PHB contents and winding speeds was observed. The PHB microfibril reinforced PEN/PET composite fibers exhibited an unexpectedly low tensile modulus. We have evaluated the tensile modulus of the fibers using the non‐modified22 and a modified23 Halpin–Tsai model. From the analysis of both models, large differences were found between the theoretical and experimental values of the tensile modulus, and the low value of the tensile modulus of the composite fiber could not adequately be explained by either model. Thus, we analyzed the observed modulus values using the Takayanagi model,24 which describes the concept of mechanical discontinuities in semi‐crystalline polymers. Using the Takayanagi model, the effective fraction of continuous or discontinuous microfibrils was evaluated. Consequently, we could successfully explain the very low modulus of the PHB/PEN/PET composite fiber, having a large number of PHB microfibrils, using the Takayanagi model. Copyright © 2003 Society of Chemical Industry
Formation of monodisperse polyacrylamide particles by dispersion polymerization: particle size and size distribution
Authors: Ye Qiang , Zhang Zhicheng , Ge Xuewu
Published: April 2003

Highly monodisperse polyacrylamide microparticles were directly prepared by dispersion polymerization in aqueous alcoholic media initiated by 2,2′‐azobisisobutyronitrile using poly(N‐vinylpyrrolidone) as a steric stabilizer. Monomer conversion was studied dilatometrically and polymer molecular weight was determined viscometrically. The hydrodynamic diameter of polymer particles and its distribution were measured with a dynamic laser light scattering spectrometer. The number of the nuclei produced in the early stage of the polymerization was found to be constant during the remainder of the polymerization. The influences of various polymerization parameters, such as initiator concentration, monomer concentration, stabilizer content, medium polarity, and polymerization temperature on the particle size and size distribution were systematically investigated. Copyright © 2003 Society of Chemical Industry
Copolymerization of N‐phenylmaleimide with 2‐hydroxyethyl and ethyl methacrylates
Authors: Şenel Serap , Rzaev Zakir M. O. , Pişkin Erhan
Published: April 2003

Radical copolymerization of N‐phenylmaleimide (PhMI) with 2‐hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) was studied. Synthesis of copolymers was carried out in p‐dioxane at 65 °C with 2,2′‐azobisisobutyronitrile as the initiator. Copolymer compositions were calculated by the elemental analysis and 1H NMR spectroscopy methods. Monomer reactivity ratios for the studied monomer pairs were determined using Kelen–Tüdös and non‐linear regression methods. PhMI monomer was found to have substantially different copolymerization constants in the radical copolymerization of the two monomer systems. Poly(PhMI‐co‐HEMA) possessed higher values of intrinsic viscosity and higher thermal stability, as well as showing specific melting endo‐peaks in the DSC curves. These observations were explained by the effect of H‐bonding between hydroxyl and imide groups with the formation of complexed macromolecular structures. Copyright © 2003 Society of Chemical Industry
Photocrosslinking of a maleimide functionalized polymethacrylate
Authors: Decker Christian , Bianchi Catherine
Published: April 2003

A polymethacrylate bearing pendent maleimide (MI) groups has been crosslinked by UV irradiation of the photoinitiator‐free functionalized polymer. The reaction was followed in situ by real‐time IR spectroscopy and shown to proceed with an initial quantum yield of two maleimide double bonds polymerized per photon absorbed, the value expected for a photocycloaddition mechanism. A twofold increase of the reaction rate was achieved by performing the UV irradiation in the presence of a thioxanthone photosensitizer (1 wt%). Insolubilization of the photoresist requires the reaction of at least 18 MI double bonds per polymer chain, thus implying the occurrence of an intramolecular coupling process between neighbouring MI groups located on the same polymer chain. In the presence of an electron donor monomer, like the divinylether of triethyleneglycol used, the cycloaddition reaction gives way to a radical‐induced copolymerization of maleimide and vinyl ether double bonds, which becomes the only crosslinking process in a stoichiometric mixture of the two components. Copyright © 2003 Society of Chemical Industry
Mechanical properties and morphology of LCP/ABS blends compatibilized with a styrene–maleic anhydride copolymer
Authors: Xie WB , Tam KC , Yue CY , Lam YC , Li L , Hu X
Published: April 2003

A co‐polyester liquid crystalline polymer (LCP) was melt blended with an acrylonitrile–butadiene–styrene copolymer (ABS). LCP fibrils are formed and a distinct skin/core morphology is observed in the injection moulded samples. At higher LCP concentration (50 wt%), phase inversion occurs, where the dispersed LCP phase becomes a co‐continuous phase. While the tensile strength and Young's modulus remain unchanged with increasing LCP content up to 30 wt% LCP, a significant enhancement of the modulus at 50 wt% LCP is observed due to the formation of co‐continuous morphology. The blend modulus is lower than the values predicted by the rule of mixtures, suggesting a poor interface between the LCP droplets and ABS matrix. A copolymer of styrene and maleic anhydride (SMA) was added in the LCP/ABS blends during melt blending. It is observed that SMA has a compatibilizing effect on the blend system and an optimum SMA content exists for mechanical properties enhancement. SMA improves the interfacial adhesion, whereas excess of SMA reduces the LCP fibrillation. Copyright © 2003 Society of Chemical Industry
New aspects of unsaturated polyester resin synthesis. Part 2. Reactant sequence distribution and its effect on cure kinetics
Authors: Zetterlund Per B , Gosden Ray G , Weaver William , Johnson Anthony F
Published: April 2003

The distribution of unsaturations in the prepolymer of a typical unsaturated polyester (UP) resin (maleic anhydride, phthalic anhydride and 1,2‐propylene glycol) has been shown to influence the kinetics of the cure process with styrene monomer. Segments containing double bonds in close proximity appear to lower the reactivity of the resin due to steric hindrance, as indicated by the fact that the rate of cure and the final degree of cure, measured by differential scanning calorimetry (DSC), increase as the average sequence length (SL) of maleic units decreases. This implies that the reactivity of UP resins may be improved by synthesis of prepolymers with certain reactant sequence‐length distributions. The copolymer formed by the melt condensation process of maleic anhydride, phthalic anhydride and 1,2‐propylene glycol in the absence of a transesterification catalyst has a non‐random structure with a tendency towards blockiness. This was established using 1H NMR analysis in tandem with deterministic and Monte Carlo modelling techniques. Copyright © 2003 Society of Chemical Industry
Synthesis of superabsorbent copolymers as water manageable materials
Authors: Raju K Mohana , Raju M Padmanabha , Mohan Y Murali
Published: April 2003

Strongly water‐absorbing polymers based on the monomers acrylamide, potassium acrylate and magnesium methacrylate were prepared by copolymerization using ammonium persulfate as initiator and N,N‐methylene‐bisacrylamide (MBA) as crosslinking agent. The copolymers are synthesized by varying monomer, crosslinker and initiator concentrations. The experimental results shows that superabsorbents (SAPs) have good absorbency both in water and NaCl solutions. The copolymers are characterized by IR spectroscopy. Water retention in soil is enhanced by use of these superabsorbents. The SAPs use for the growth of sunflower plants is also investigated. The water retention capacity of the SAPs was carried out at 60 °C and 100 °C. Copyright © 2003 Society of Chemical Industry
Adsorption of poly(4‐vinylpyridine) N‐alkyl quaternized at the chloroform/water interface
Authors: Urzúa Marcela D , Ríos Hernán E
Published: April 2003

The Du Noüy method has been employed to study the interfacial properties of poly(4‐vinylpyridine) N‐n‐alkyl quaternized with hexyl, octyl and decyl bromide, at the chloroform/water interface. The interfacial tension is highly dependent on the hydrophilic–hydrophobic balance between the pyridinium group and the length of the polyelectrolyte side aliphatic chain. The excess interfacial concentration, Γ, is determined according to the Gibbs–Szyszkowski equation. The areas covered by monomer unit at the interface, σ, are smaller than those reported for low molecular weight amphipathic molecules. The linear dependence of $\Delta G_{\rm{ads}}^{\rm{o}}$ with the number of carbon atoms on the side‐chain allows the determination of a contribution of just 0.13 kJ for each methylene lateral group and −36 kJ for the vinylpyridinium bromide contributions to $\Delta G_{\rm{ads}}^{\rm{o}}$. The dependence of the interfacial tension on temperature suggests that the entropy is the main factor determining the adsorption process. Copyright © 2003 Society of Chemical Industry
Eutectic‐forming binary system of poly(ethylene oxide) and p‐hydroxybenzaldehyde
Authors: Zhu Xinyuan , Xiao Yan , He Peng , Yan Deyue , Fang Yapeng
Published: April 2003

The binary system consisting of poly(ethylene oxide) (PEO) and p‐hydroxybenzaldehyde (PHD) was characterized with the aid of differential scanning calorimetry, polarized optical microscopy, scanning electron microscopy and Fourier‐transform infrared spectroscopy. The phase diagram created from thermal analysis data provides clear evidence for the presence of a eutectic at 35.5 °C and PHD weight fraction of 42%. Microscopy studies show that, for the mixtures with a PHD weight fraction below 42%, the resulting morphology of the crystallized sample is coarse spherulitic texture. In the case of eutectic composition, the crystallization of the binary melt produces degenerated homogenous spherulites. For the hypoeutectic PEO–PHD mixtures, the PHD crystals become large and thick with decreasing the PEO fraction. Moreover, the infrared measurements indicate that hydrogen bonding in the PEO–PHD binary system has an important effect on the PEO helical conformation. With increase of the amount of PHD component, the PEO helical conformation in the PEO–PHD mixtures changes from the 72 helix to the 103 helix. Further increase of the PHD content leads to the destruction of the PEO helical conformation. Copyright © 2003 Society of Chemical Industry
Surface hydrophilicity and enzymatic hydrolyzability of biodegradable polyesters: 1. effects of alkaline treatment
Authors: Tsuji Hideto , Ishida Takuya , Fukuda Norio
Published: April 2003

Surface treatment using alkaline solutions was attempted to enhance the surface hydrophilicity and enzymatic hydrolyzability of hydrophobic poly(L‐lactide) [ie poly(L‐lactic acid) (PLLA) and poly(ε‐caprolactone) (PCL). The alkaline treatment was performed by immersing the PLLA and PCL films in 0.01 and 4 N NaOH solutions, respectively, for various periods of time. The effects of the alkaline treatment on the hydrophilicity of the films were monitored by dynamic contact angle measurements, while the enzymatic hydrolyzability of the PLLA and PCL films after the alkaline treatment were evaluated by weight losses in the presence of proteinase K and Rhizopus arrhizus lipase, respectively. With the alkaline treatment the hydrophilicity of the PLLA and PCL films was controllable in the advancing contact angle (θa) ranges of 84–108° and of 69–93°, respectively, by varying the alkaline treatment time. The enzymatic hydrolysis rates of the PLLA films became higher with decrease of the θa, irrespective of the crystallinity, strongly suggesting that the surface hydrophilicity or the surface molecular weight is crucial to determine their enzymatic hydrolyzability. In contrast, the enzymatic hydrolyzability of the PCL films remained unchanged even when the θa decreased from 93° to 73° by alkaline treatment for 4 h. However, prolonged alkaline treatment for periods of time exceeding 4 h, which insignificantly altered the θa but caused the formation of pores and cracks on the PCL film surface, accelerated the enzymatic hydrolysis of the PCL films. This indicates that the enzymatic hydrolyzability of the PCL film depends on the surface area per unit weight rather than the surface hydrophilicity. Copyright © 2003 Society of Chemical Industry
Treatment of plasticized PVC to reduce plasticizer/solvent migration: optimization with an experimental design
Authors: Fugit Jean‐Luc , Taverdet Jean‐Louis , Gauvrit Jean‐Yves , Lanteri Pierre
Published: April 2003

This work deals with mass transfers between liquid food and PVC packaging. A treatment which reduces the migration both of plasticizer toward a liquid food simulant and the liquid has been investigated. The treatment is a two step process: (1) soaking in a liquid and (2) drying at various temperatures. Some process parameters, such as time and temperature of soaking, temperature and time of drying, influence the treatment efficacy. The best values consider in from these factors were found due to experimental designs and the physical significance of the results is discussed.

© 2003 Society of Chemical Industry
Ionization potential of excited states of Be‐like sequence in the concept of iso‐spectrum‐level series
Authors: Zheng Neng Wu , Wang Tao
Published: April 2003

With the introduction of the concept of the iso‐spectrum‐level series, a linear relationship is found between the first differences of the ionization potential of excited states and nuclear charge Z along an iso‐spectrum‐level series, and the ionization potential of excited states of Be‐like sequence are studied systematically on the basis of the weakest bound electron potential model theory. The expression of nonrelativistic ionization potential is derived from the weakest bound electron potential model theory, and relativistic effects are included by using a fourth‐order polynomial in Z. As a demonstration, the ionization potentials of [He]2s2p 3P, [He]2s3s 1S0, [He]2s3p 1P, [He]2s3d 1D2, and [He]2s4d 1D2 series for a range of Be‐like sequence from Z = 4–23 are calculated. The results are compared with the experimental data and the recent sophisticated ab initio results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 344–350, 2003
Comment on “Computation of Two‐Center Coulomb Integrals over Slater‐Type Orbitals Using Elliptical Coordinates”
Authors: Harris Frank E.
Published: April 2003

In a recent article in this journal, Özmen, Karakas, Atav, and Yakar gave formulas for the evaluation of two‐center Coulomb integrals over Slater‐type orbitals (STOs) in ellipsoidal coordinates Int J Quantum Chem 2003, 91, 13–19. The relation of this work to the rich literature on STO integral evaluation is reviewed, with focus on the important issues of speed of computation and numerical stability. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 93: 332–334, 2003