bluuebunny/crossref_metadata_2025 huggingface dataset:
Health systems decentralization and human resources management in low and middle income countries
Authors: Wang Yan , Collins Charles , Tang Shenglan , Martineau Tim
Published: December 2002

The aim of this article is to explore the experiences of human resources management in the context of health sector decentralization. The initial review of health sector decentralization covers issues relating to the context, content, formulation/implementation and impact of decentralization. The review of the literature on human resources management (HRM) and decentralization has identified a number of key points that are organized around the following HRM functions: HR planning/ staff supply, personnel administration and employee relations, and performance management. The importance of the management of change is also highlighted. The article concludes by emphasizing the need to include human resources as a key issue in health systems change and emphasizes the areas of policy dialogue and research. Copyright © 2002 John Wiley & Sons, Ltd.
Expression of lymphotoxin‐beta (LT‐β) in chronic inflammatory conditions
Authors: Agyekum Sarah , Church Alison , Sohail Muhammed , Krausz Thomas , Van Noorden Susan , Polak Julia , Cohen Jonathan
Published: December 2002

Functional studies in gene‐knockout and transgenic mice systems have shown that lymphotoxin‐alpha and lymphotoxin‐beta (LT‐α and LT‐β) are of fundamental importance in peripheral lymphoid organ development, but it remains unclear what role these cytokines have to play in the adult immune response and in the pathogenesis of disease. In this study, a polyclonal anti‐serum to human LT‐β was used to investigate the distribution of LT‐β by immunohistochemistry in normal and diseased tissues. In the gut, lymph nodes, spleen, and tonsil, there was some LT‐β present on a variety of lymphoid cell types. In contrast, strong staining for LT‐β was observed on plasma cells and a subpopulation of CD4+ T cells in tissues affected by chronic inflammatory disease or infection, for example in inflammatory bowel disease, and in lymph nodes obtained from patients with sarcoidosis and tuberculosis. In tuberculous and sarcoid lymph nodes, LT‐β expression also occurred on some but not all epithelioid histiocytes within granulomas and on multi‐nucleated giant cells. These findings support a role for LT‐β in human disease and suggest that it might represent a therapeutic target in a variety of common infective or inflammatory disorders. Copyright © 2002 John Wiley & Sons, Ltd.
Killer cell immunoglobulin‐like receptor expression delineates in situ Sézary syndrome lymphocytes
Authors: Wechsler Janine , Bagot Martine , Nikolova Maria , Parolini Silvia , Martin‐Garcia Nadine , Boumsell Laurence , Moretta Alessandro , Bensussan Armand
Published: December 2002

p140/KIR3DL2 has been identified in malignant cell lines isolated from the skin and blood of patients with transformed mycosis fungoides (MF) and Sézary's syndrome (SS). For the first time, the expression of a cell membrane structure appeared to be able to distinguish CD4+ tumour lymphocytes from reactive lymphocytes in these small cutaneous T‐cell lymphomas (CTCLs). This study has examined the in vivo expression of this receptor in various CTCL subtypes, which constituted a heterogeneous group. Tumour cells diffusely expressed KIR in SS, in lymphomatoid papulosis (LyP) and in CD4+CD30+ as well as CD8+ large cell pleomorphic CTCL. In contrast, the infiltrating lymphocytes did not express KIR in MF at the patch/plaque stage or in CD4+CD30− large cell pleomorphic CTCL, except for scattered small cells. One quarter of the transformed MF tested exhibited KIR+ tumour cells, suggesting heterogeneity in this subtype. KIR expression was also examined in inflammatory lesions characterized by a dense infiltrate of T cells, such as lupus erythematosus and lichen planus. Only scattered CD8+ cells in lichen planus expressed a significant amount of KIR3DL2. Taken together, these results show for the first time that KIR molecules are expressed in distinct subtypes of malignant CTCL. It is also shown for the first time that SS and MF, which are frequent variants of CTCL with similar histological features, can be distinguished by their KIR3DL2 expression analysis. The identification of this KIR also differentiates between lupus erythematosus and lichen planus, which are both diseases with dense benign lymphocytic infiltrates. Copyright © 2002 John Wiley & Sons, Ltd.
Reactivity of isobutane in fluorosulfonic based superacids
Authors: Goeppert Alain , Bhering Daniel L. , Sommer Jean , Mota Claudio J. A.
Published: December 2002

The behavior of isobutane in DSO3F containing various amounts of SbF5 has been studied in relation to the acid strength of the superacid system. In contrast to the DF–SbF5 system, H/D exchange occurs only in the weakest superacid via deprotonation of the t‐butyl ion intermediate formed by an oxidative process. Kinetic isotope effect determination shows that the slow step is hydride transfer. At higher acidity, the increasing stability of this intermediate impedes isotopic exchange. Copyright © 2002 John Wiley & Sons, Ltd.
Facile modifications of a polyimide via chloromethylation. I. Novel synthesis of a new photosensitive polyimide
Authors: Zhang Aiqing , Li Xiangdan , Nah Changwoon , Hwang Keejun , Lee Myong‐Hoon
Published: December 2002

A soluble aromatic polyimide was chloromethylated via a reaction with chloromethyl methyl ether in the presence of tin(IV) chloride to produce a new starting material for the modification of aromatic polyimides. The chemical structure of the resulting polymer was confirmed by 1H NMR and Fourier transform infrared spectroscopy. The maximum number of chloromethyl groups per repeat unit was 1.81. The chloromethylated polyimide was stable up to 250 °C and soluble in both chloroform and tetrahydrofuran. So that its utilization for further modification could be demonstrated, cinnamic acid was reacted with the formed polyimide, and it produced a new photosensitive polyimide with a cinnamoyl side chain. The photosensitivity of the resulting polyimide was investigated with ultraviolet spectroscopic methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 22–29, 2003
Anisotropic thermosets from liquid‐crystalline azomethynic epoxy resins and primary aromatic diamines
Authors: Castell Pere , Serra Angels , Galià Marina , Giamberini Marta , Carfagna Cossimo
Published: December 2002

Novel epoxy‐terminated monomers based on imine groups were synthesized and their mesogenic properties studied. Aliphatic spacers of different lengths were introduced between the rigid unit and the glycidylic group, and their liquid‐crystalline behavior was examined. They were reacted with primary aromatic diamines inside a magnetic field so that the formation of anisotropic networks could be investigated. The influence of curing conditions and the structure of monomers and amines on the formation of liquid‐crystal thermosets were investigated. Thermosets with locked nematic textures were obtained in all cases. The influence of a 7.1 T magnetic field on the macroscopic orientation of these materials was studied, and mechanical properties of the resulting networks were evaluated by dynamic mechanical analysis. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1–12, 2003
Microwave‐improved polymerization of ϵ‐caprolactone initiated by carboxylic acids
Authors: Yu Z. J. , Liu L. J. , Zhuo R. X.
Published: December 2002

The ring‐opening polymerization of ε‐caprolactone (ε‐CL), initiated by carboxylic acids such as benzoic acid and chlorinated acetic acids under microwave irradiation, was investigated; with this method, no metal catalyst was necessary. The product was characterized as poly(ε‐caprolactone) (PCL) by1H NMR spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and gel permeation chromatography. The polymerization was significantly improved under microwave irradiation. The weight‐average molecular weight (Mw) of PCL reached 44,800 g/mol, with a polydispersity index [weight‐average molecular weight/number‐average molecular weight (Mw/Mn)] of 1.6, when a mixture of ε‐CL and benzoic acid (25/1 molar ratio) was irradiated at 680 W for 240 min, whereas PCL withMw= 12,100 andMw/Mn= 4.2 was obtained from the same mixture by a conventional heating method at 210 °C for 240 min. A degradation of the resultant PCL was observed during microwave polymerization with chlorinated acetic acids as initiators, and this induced a decrease inMwof PCL. However, the degradation was hindered by benzoic acid at low concentrations. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 13–21, 2003
Polymerization of neat 2‐ethylhexyl acrylate induced by a pulsed electron beam
Authors: Feng Hongxia , Al‐Sheikhly Mohamad , Silverman Joseph , Weiss Douglas E. , Neta Pedatsur
Published: December 2002

The bulk polymerization of 2‐ethylhexyl acrylate (2‐EHA), induced by a pulsed electron beam, was investigated with pulse radiolysis, gravimetry, and Fourier transform infrared spectroscopy. The roles of the dose rate, pulse frequency, and added acrylic acid (AA) in the polymerization of 2‐EHA were examined at ambient temperature. In the range of 12.6–71.2 Gy/pulse, the polymerization of 2‐EHA was dose‐rate‐dependent: at the same total dose, a lower dose rate yielded a higher conversion. Also, a lower pulse rate gave a higher conversion at the same total dose. The addition of up to 10 wt % AA showed no increase in the conversion of 2‐EHA at a low conversion (8 kGy), but at a higher conversion (16 kGy), a 20 wt % increase in the conversion of 2‐EHA was observed. The estimated values (1.6 ± 0.3) × 10−3 (dm3 s)3/2 mol−1 s−1/2 for kp(G/2kt)1/2 and 2.6 ± 0.8 dm3 s J−1 for 2ktG (where kp is the rate constant of propagation, kt is the rate constant of bimolecular termination, and G is the yield of free radicals) were obtained at relatively low conversions. The reaction rate constant of the addition of 2‐EHA· free radicals to the monomer was measured by pulse radiolysis and found to be 2.8 × 102 mol−1 dm3 s−1. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 196–203, 2003
Synthesis and characterization of poly(methyl methacrylate)‐block‐poly(methylphenylsilane)‐block‐poly(methyl methacrylate) by atom transfer radical polymerization
Authors: Rossi N. A. A. , Jones R. G. , Holder S. J.
Published: December 2002

ABA block copolymers of methyl methacrylate and methylphenylsilane were synthesized with a methodology based on atom transfer radical polymerization (ATRP). The reaction of samples of α,ω‐dihalopoly(methylphenylsilane) with 2‐hydroxyethyl‐2‐methyl‐2‐bromoproprionate gave suitable macroinitiators for the ATRP of methyl methacrylate. The latter procedure was carried out at 95 °C in a xylene solution with CuBr and 2,2‐bipyridine as the initiating system. The rate of the polymerization was first‐order with respect to monomer conversion. The block copolymers were characterized with1H NMR and13C NMR spectroscopy and size exclusion chromatography, and differential scanning calorimetry was used to obtain preliminary evidence of phase separation in the copolymer products. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 30–40, 2003
Synthesis and characterization of phosphonate‐containing polysiloxanes
Authors: Gallagher Skip
Published: December 2002

Phosphonate‐functionalized polysiloxanes have been prepared with a new siloxane/phosphonate monomer. The reaction of 3‐chloropropylmethyldimethoxysilane with trimethylphosphite or triethylphosphite produces several new monomers containing pendant phosphonate groups. Copolymerization with dimethyldimethoxysilane has produced polymers soluble in most organic solvents. The acid hydrolysis of the phosphoryl esters has produced hydrophilic siloxane polymers containing phosphonic acid groups. The thermal properties of the polymers and several related small molecules have been compared with thermogravimetric analysis. Both the monomers and the resulting polymers have been characterized with 1H, 13C, 31P, and 29Si NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 48–59, 2003
Oxidation and epoxidation of poly(1,3‐cyclohexadiene)
Authors: Williamson D. T. , Mather B. D. , Long T. E.
Published: December 2002

Poly(1,3‐cyclohexadiene) (PCHD) derivatives were synthesized via facile chemical modification reactions of the residual double bond in the repeat unit. The oxidation and degradation of PCHD was investigated to enable subsequent controlled epoxidation reactions. PCHD exhibited a 15% weight loss at 110 °C in the presence of oxygen. The oxidative degradation, demonstrated by gel permeation chromatography (GPC) and 1H NMR spectroscopy, was attributed to main‐chain scission. Aldehyde and ether functional groups were introduced into the polymer during the oxidation process. PCHD was quantitatively epoxidized in the absence of deleterious oxidation with meta‐chloroperoxybenzoic acid. 1H and 13C NMR spectroscopy confirmed that polymers with controlled degrees of epoxidation were reproducibly obtained. Epoxidized PCHD exhibited a glass‐transition temperature at 154 °C, which was slightly higher than that of a PCHD precursor of a nearly equivalent molecular weight. Moreover, GPC indicated the absence of undesirable crosslinking or degradation, and the molecular weight distributions remained narrow. The thermooxidative stability of the fully epoxidized polymer was compared to that of the PCHD precursor, and the epoxidized PCHD exhibited an initial weight loss at 250 °C in oxygen, which was 140 °C higher than the temperature for PCHD. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 84–93, 2003
Synthesis and properties of new soluble triphenylamine‐based aromatic poly(amine amide)s derived from N,N′‐bis(4‐carboxyphenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine
Authors: Liou Guey‐Sheng , Hsiao Sheng‐Huei
Published: December 2002

A new triphenylamine‐containing aromatic dicarboxylic acid, N,N′‐bis(4‐carboxyphenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, was synthesized by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 4‐fluorobenzonitrile, followed by the alkaline hydrolysis of the intermediate dinitrile compound. A series of novel triphenylamine‐based aromatic poly(amine amide)s with inherent viscosities of 0.50–1.02 dL/g were prepared from the diacid and various aromatic diamines by direct phosphorylation polycondensation. All the poly(amine amide)s were amorphous in nature, as evidenced by X‐ray diffractograms. Most of the poly(amine amide)s were quite soluble in a variety of organic solvents and could be solution‐cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with glass‐transition temperatures up to 280 °C, 10% weight‐loss temperatures in excess of 575 °C, and char yields at 800 °C in nitrogen higher than 60%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 94–105, 2003
Fluorinated block copolymers containing poly(vinylidene fluoride) or poly(vinylidene fluoride‐co‐hexafluoropropylene) blocks from perfluoropolyethers: Synthesis and thermal properties
Authors: Gelin Marie‐Pierre , Ameduri Bruno
Published: December 2002

PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers [where PFPE, PVDF, VDF, and HFP represent perfluoropolyether, poly(vinylidene fluoride), vinylidene fluoride (or 1,1‐difluoroethylene), and hexafluoropropylene] were synthesized by radical (co)telomerizations of VDF (or VDF and HFP) with an iodine‐terminated perfluoropolyether (PFPE‐I). Di‐tert‐butyl peroxide (DTBP) was used and was shown to act as an efficient thermal initiator. The numbers of VDF and VDF/HFP base units in the block copolymers were assessed with 19F NMR spectroscopy. According to the initial [PFPE‐I]0/[fluoroalkenes]0 and [DTBP]0/[fluoroalkenes]0 molar ratios, fluorinated block copolymers of various molecular weights (1500–30,300) were obtained. The states and thermal properties of these fluorocopolymers were investigated. The compounds containing PVDF blocks with more than 30 VDF units were crystalline, whereas all those containing poly(VDF‐co‐HFP) blocks exhibited amorphous states, whatever the numbers were of the fluorinated base units. All the samples showed negative glass‐transition temperatures higher than that of the starting PFPE. Interestingly, these PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers exhibited good thermostability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 160–171, 2003
Hydrogel‐like elastic membrane consisting of semi‐interpenetrating polymer networks based on a phosphorylcholine polymer and a segmented polyurethane
Authors: Iwasaki Yasuhiko , Shimakata Keiko , Morimoto Nobuyuki , Kurita Kimio
Published: December 2002

To obtain a hydrogel‐like elastic membrane, we prepared semi‐interpenetrating polymer networks (IPNs) by the radical polymerization of methacrylates such as 2‐methacryloyloxyethyl phosphorylcholine (MPC), 2‐hydroxyethylmethacrylate, and triethyleneglycol dimethacrylate diffused into segmented polyurethane (SPU) membranes swollen with a monomer mixture. The values of Young's modulus for the hydrated semi‐IPN membranes were less than that for an SPU membrane because of higher hydration, but they were much higher than that for a hydrated MPC polymer gel (non‐SPU). According to a thermal analysis, the MPC polymer influenced the segment association of SPU. The diffusion coefficient of 8‐anilino‐1‐naphthalenesulfonic acid sodium salt from the semi‐IPN membrane could be controlled with different MPC unit concentrations in the membrane, and it was about 7 × 102 times higher than that of the SPU membrane. Fibroblast cell adhesion on the semi‐IPN membrane was effectively reduced by the MPC units. We concluded that semi‐IPNs composed of the MPC polymer and SPU may be novel polymer materials possessing attractive mechanical, diffusive‐release, and nonbiofouling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 68–75, 2003
Effect of ortho‐methylation on a bis(4‐cyanatocumyl)benezene low‐dielectric resin
Authors: Maya Eva M. , Snow Arthur W. , Buckley Leonard J.
Published: December 2002

A synthesis procedure for and characterization of a tetra‐ortho‐methyl substituted three‐ringed cyanate ester monomer, 4,4′‐[1,3‐phenylenebis(1‐methylethylidene)]bis[2,6‐dimethyl]phenylcyanato, and the corresponding cured resin are described with comparative characterization of the resin analogue without the ortho‐methyl substitutents. The othro‐methylation lowered the dielectric from 2.64 to 2.59 at 1 GHz and from 2.64 to 2.48 GHz at 15 GHz, whereas the tan δ was not significantly affected. Other physical properties also affected included a 40 °C decrease in the glass‐transition temperature, an increase in the thermal‐expansion coefficients, and a reduction in thermogravimetric stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 60–67, 2003
Grafting of light‐activated antimicrobial materials to nylon films
Authors: Sherrill Jennifer , Michielsen Stephen , Stojiljkovic Igor
Published: December 2002

Protoporphyrin IX and zinc protoporphyrin IX were grafted to the surface of nylon‐6,6 films via an ethylene diamine bridge and a poly(acrylic acid) (PAA) scaffold. X‐ray photoelectron spectroscopy showed that approximately 57% of the nylon surface was covered by PAA and approximately 6% of the carboxylic acid groups in PAA were grafted to the ethylene diamine derivative of protoporphyrin IX or its zinc salt. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 41–47, 2003
Poly(ethylene terephthalate) terpolyesters containing isophthalic and 5‐tert‐butylisophthalic units
Authors: Kint Darwin P. R. , Martínez de Ilarduya Antxon , Alla Abdelilah , Muñoz‐Guerra Sebastián
Published: December 2002

Poly(ethylene terephthalate‐co‐isophthalate‐co‐5‐tert‐butylisophthalate) (PETItBI) terpolymers were investigated with reference to poly(ethylene terephthalate) (PET) homopolymer and poly(ethylene terephthalate‐co‐isophthalate) (PETI) copolymers. Three series of PETItBI terpolyesters, characterized by terephthalate contents of 90, 80, and 60 mol %, respectively, with different isophthalate/5‐tert‐butylisophthalate molar ratios, were prepared from ethylene glycol and mixtures of dimethyl terephthalate, dimethyl isophthalate, and 5‐tert‐butylisophthalic acid. The composition of the terpolymers and the composition of the feed agreed. All terpolymers had a random microstructure and number‐average molecular weights ranging from 10,000 to 20,000. The PETItBI terpolyesters displayed a higher glass‐transition temperature and a lower melting temperature than the PETI copolymers having the same content of terephthalic units. Thermal stability appeared essentially unchanged upon the incorporation of the 5‐tert‐butylisophthalic units. The PETItBIs were crystalline for terephthalate contents higher than 80 mol %, and they crystallized at lower rates than PETI. The crystal structure of the crystalline terpolymers was the same as that of PET with the 1,3‐phenylene units being excluded from the crystalline phase. Incorporation of isophthalate comonomers barely affected the tensile modulus and strength of PET, but the brittleness of the terpolymers decreased for higher contents in 5‐tert‐butylisophthalic units. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 124–134, 2003
Reverse atom transfer radical polymerization of methyl methacrylate in room‐temperature ionic liquids
Authors: Ma Hongyang , Wan Xinhua , Chen Xiaofang , Zhou Qi‐Feng
Published: December 2002

The reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was successfully carried out in 1‐butyl‐3‐methylimidazolium hexafluorophosphate with 2,2′‐azobisisobutyronitrile/CuCl2/bipyridine as the initiating system, which had been reported as not able to promote a controlled process of MMA in bulk. The living nature of the polymerization was confirmed by kinetic studies, end‐group analysis, chain extension, and block copolymerization results. The polydispersity of the polymer obtained was quite narrow, with a weight‐average molecular weight/number‐average molecular weight ratio of less than 1.2. In comparison with other reverse ATRPs in bulk or conventional solvents, a much smaller amount of the catalyst was used. After a relatively easy removal of the polymer and residue monomer, the ionic liquid and catalytic system could be reused without further treatment. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 143–151, 2003
Chemical and physical adsorption of polymers containing thiophosphate, amino, or polysiloxane groups at the oil/metal interface under extreme pressure
Authors: Ni Sheng‐Chung , Kuo Ping‐Lin
Published: December 2002

Thiophosphate‐ and amino‐containing polymers—poly[diethyl 2‐(methacryloyloxy) ethyl phosphate‐stearyl acrylate] (PPS) and poly(2‐dimethylaminoethylacrylate‐stearyl acrylate) (PNS)—were synthesized, and their characteristics at an oil/metal interface under a high load and rotary velocity were investigated by the measurement of the temperature of the oil, the frictional coefficient, and the electrical contact resistance between the two metal surfaces. The experimental results indicated that PNS most effectively limited the increase of the oil temperature and the frictional coefficient at low temperatures. However, PNS reduced the oil temperature and frictional coefficient less effectively than the base oil at high temperatures, whereas PPS most effectively reduced the oil temperature and frictional coefficient and increased the electrical resistance at high temperatures. Moreover, the adsorption layers of PPS could be directly observed with scanning electron microscopy (SEM). These adsorption layers were analyzed by energy‐dispersible spectrometry to determine the phosphorus content and by electron spectroscopy for chemical analysis to demonstrate the existence of ferric or ferrous ions of sulfide or sulfate. The results of this study suggested that the adsorption layer of the thiophosphate‐containing polymer resulted in chemisorption by a reaction of the thiophosphate group on a metal surface. In contrast, an amino‐containing polymer was physically adsorbed onto a metal surface at low temperature, although no adsorption layer was observed at a high temperature with SEM. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 106–115, 2003
Use of the Pauson–Khand reaction products as monomers in the palladium(II)‐catalyzed homopolymerization and copolymerization of norbornene derivatives
Authors: Son Seung Uk , Kim Do Han , Jung Il Gu , Chung Young Keung , Lee Sueg‐Geun , Chun Sung‐Ho
Published: December 2002

New norbornene derivatives synthesized from Pauson–Khand reaction products were homopolymerized and copolymerized with norbornene with an allyl–palladium complex as a catalyst. The ketone group was tolerated by the polymerization reaction. Monomers bearing protected alcohols were easily homopolymerized. Most of the homopolymers were soluble in tetrahydrofuran, CH2Cl2, toluene, and cyclohexane. As the steric bulkiness of the substituent increased, the chain length of the homopolymer decreased. Copolymers with a molecular weight of up to 153,800 were formed and were soluble in tetrahydrofuran, CH2Cl2, toluene, and diethyl ether. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 76–83, 2003
Synthesis and characterization of fluorine‐containing polyesters by the polyaddition of bis(epoxide)s with active diesters
Authors: Ito Nobuhito , Kudo Hiroto , Kameyama Atsushi , Nishikubo Tadatomi , Anada Tetsuo
Published: December 2002

The synthesis and optical properties of polyesters with pendant fluorinated phenoxy groups were examined. The polyaddition of bisphenol AF diglycidyl ether (1) with fluorine‐containing terephtalates (2a–f) was carried out with tetrabutylphosphonium chloride (TBPC) as the catalyst in chlorobenzene to afford the corresponding polyesters with number‐average molecular weights (Mn's) ranging from 15,200 to 30,000 in 88–96% yields. Furthermore, the polyaddition of 1 with isophthalate 2g and phthalate 2h also produced high‐molecular‐weight polyesters with Mn's = 22,700 and 22,600 in 88 and 84% yields, respectively. The linear relationship was observed between the fluorine contents and refractive indices of the obtained polyesters. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 213–222, 2003
Using the new in–in method for the synthesis of polyisoprene/polystyrene heteroarm star polymers
Authors: Fazeli N. , Afshar Taromi F.
Published: December 2002

The basis of the two‐step in–in method is as follows: star polymers with poly(divinyl benzene) cores, synthesized by the arm‐first method, include many unreacted double bonds in their core, and these double bonds can be attacked by the carbanions of some monomers such as styrene and dienes. In this work, linear polyisoprene chains were used to attack the double bonds existing in the poly(divinyl benzene) cores of polystyrene star polymers, so that a heteroarm star polymer with polystyrene and polyisoprene arms was synthesized. It was later well characterized with size exclusion chromatography, light scattering, viscometry, UV spectroscopy, dynamic mechanical thermal analysis, and 1H NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 135–142, 2003
Synthesis and solution properties of a new pH‐responsive polymer containing amino propanesulfonic acid residues
Authors: Ali Sk. Asrof , Mazumder Mohammad A. J. , Al‐Muallem Hasan A.
Published: December 2002

The reaction of diallyl amine with 1,3‐propane sultone led to the synthesis of the zwitterionic monomer 3‐(N,N‐diallylammonio)propanesulfonate. The sulfobetaine was cyclopolymerized in water in the presence of sodium chloride with t‐butylhydroperoxide as an initiator to afford a polysulfobetaine (PSB) in very good yield. PSB, upon treatment with sodium hydroxide, was converted into an anionic polyelectrolyte (APE). Although APE was readily soluble in salt‐free water, PSB needed the presence of low‐molecular‐weight salts (e.g., NaCl, KI, etc., in the range of 0.135–1.04 N) for its dissolution. The solution properties of PSB and APE were investigated with potentiometric and viscometric techniques. The basicity constant of the amine was apparent and followed the modified Henderson–Hasselbalch equation; as the degree of protonation (α) of the whole macromolecule increases, the protonation of the amine nitrogens becomes increasingly more difficult. The composition and phase diagram of the aqueous two‐phase systems of APE/PSB and poly(ethylene glycol) were also explored. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 172–184, 2003
Polymer‐dispersed liquid‐crystal materials fabricated with frontal polymerization
Authors: Gill N. , Pojman J. A. , Willis J. , Whitehead J. B.
Published: December 2002

We report on the morphological and thermal properties of polymer‐dispersed liquid crystals (PDLCs) fabricated with frontal‐polymerization‐induced phase separation (FPIPS). Frontal polymerization is characterized by a rapid‐conversion, high‐temperature, and large‐thermal‐gradient environment. A comparison is made between the morphological and thermal properties of PDLCs fabricated with FPIPS and traditional thermal‐polymerization‐induced phase separation. Characterization includes differential scanning calorimetry to probe the glass and nematic‐to‐isotropic transitions and scanning electron microscopy to evaluate the phase‐separated morphology. In addition, the frontal temperatures and velocities are reported for PDLCs fabricated with frontal polymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 204–212, 2003
Preparation and characterization of macroporous poly(N‐isopropylacrylamide) hydrogels for the controlled release of proteins
Authors: Zhuo Ren‐Xi , Li Wei
Published: December 2002

Macroporous, temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPAAm) hydrogels were synthesized with poly(ethylene glycol)s (PEGs; molecular weight = 2000–6000) as the pore‐forming agents. The influence of the molecular weight and PEG content on the responsive kinetics of these macroporous hydrogels was investigated. The PEG‐modified PNIPAAm hydrogels were characterized by the swelling ratio, deswelling–reswelling kinetics, Fourier transform infrared, and differential scanning calorimetry. The morphology of these hydrogels was analyzed with scanning electron microscopy. The prepared macroporous hydrogels exhibited some unique properties in comparison with the gels with low molecular weight PEGs (molecular weight < 2000) as the pore‐forming agents. In addition, a preliminary study on the controlled release of bovine serum albumin from these macroporous hydrogels was carried out. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 152–159, 2003
Controlled cationic ring‐opening polymerization of cyclic thiocarbonates with ester groups
Authors: Nemoto Nobukatsu , Yoshii Kouichi , Kameshima Hisamitsu , Sanda Fumio , Endo Takeshi
Published: December 2002

This work deals with the cationic ring‐opening polymerization of the cyclic thiocarbonates 5‐benzoyloxymethyl‐5‐methyl‐1,3‐dioxane‐2‐thione (1), 5,5‐dimethyl‐1,3‐dioxane‐2‐thione (2), and 4‐benzoyloxymethyl‐1,3‐dioxane‐2‐thione (3). The polymerization was carried out with 2 mol % trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, boron trifluoride etherate, or triethyloxonium tetrafluoroborate as the initiator to afford the polythiocarbonate with a narrow molecular weight distribution accompanying isomerization of the thiocarbonate group. The molecular weight of the obtained polymer could be controlled by the feed ratio of the monomer to the initiator and increased when the second monomer was added to the polymerization mixture after the quantitative consumption of the monomer in the first stage. The block copolymerization of 2 and 3 was also achieved, and this supported the idea that the cationic ring‐opening polymerization of these monomers proceeded via a living process. The order of the polymerization rate was 3 > 2 > 1. The cationic ring‐opening polymerization of 1 and 3 involved the neighboring group participation of ester groups according to the polymerization rate and molecular orbital calculations with the ab initio method. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 185–195, 2003
Mechanism and kinetics of the imidazolidinone nitroxide‐mediated free‐radical polymerization of styrene
Authors: Dervan Paul , Aldabbagh Fawaz , Zetterlund Per B. , Yamada Bunichiro
Published: December 2002

Styrene radical polymerizations mediated by the imidazolidinone nitroxides 2,5‐bis(spirocyclohexyl)‐3‐methylimidazolidin‐4‐one‐1‐oxyl (NO88Me) and 2,5‐bis(spirocyclohexyl)‐3‐benzylimidazolidin‐4‐one‐1‐oxyl (NO88Bn) were investigated. Polymeric alkoxyamine (PS‐NO88Bn)‐initiated systems exhibited controlled/living characteristics at 100–120 °C but not at 80 °C. All systems exhibited rates of polymerization similar to those of thermal polymerization, with the exception of the PS‐NO88Bn system at 80 °C, which polymerized twice as quickly. The dissociation rate constants (kd) for the PS‐NO88Me and PS‐NO88Bn coupling products were determined by electron spin resonance at 50–100 °C. The equilibrium constants were estimated to be 9.01 × 10−11 and 6.47 × 10−11 mol L−1 at 120 °C for NO88Me and NO88Bn, respectively, resulting in the combination rate constants (kc) 2.77 × 106 (NO88Me) and 2.07 × 106 L mol−1 s−1 (NO88Bn). The similar polymerization results and kinetic parameters for NO88Me and NO88Bn indicated the absence of any 3‐N‐transannular effect by the benzyl substituent relative to the methyl substituent. The values of kd and kc were 4–8 and 25–33 times lower, respectively, than the reported values for PS‐TEMPO at 120 °C, indicating that the 2,5‐spirodicyclohexyl rings have a more profound effect on the combination reaction rather than the dissociation reaction. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 327–334, 2003
Allelic imbalance in hereditary and sporadic prostate cancer
Authors: Verhage Bas A.J. , Houwelingen Kjeld van , Ruijter T. Emiel G. , Kiemeney Lambertus A. , Schalken Jack A.
Published: December 2002

BACKGROUND

In this study, we evaluate the pattern of allelic imbalance (AI) in both sporadic prostate cancer (SPC) and hereditary prostate cancer (HPC) at loci that frequently show allelic imbalance in sporadic prostate cancer, or are believed to have a putative role in the disease.

METHODS

DNA obtained from 35 sporadic tumors and 46 hereditary tumors were tested for AI, by using a panel of 35 microsatellite markers.

RESULTS

Chromosomal regions that display high frequencies of AI (≥30%) in HPC include 1q, 5q, 7q, 8p, 13q, 16q, 17q, 18q, and 20q. In SPC, high frequencies of AI were found at 5q, 7q, 8p, 10q, 13q. Main differences (Δ ≥ 20%) in AI between HPC and SPC were at 1q, 10q, 17q, 18q, and 20q.

CONCLUSION

AI at the prostate cancer susceptibility loci HPC1, PCaP, and HPC20 was seen more often in HPC compared with SPC. It appears that there are marked differences in the pattern of AI between sporadic and hereditary PCa. Prostate 54: 50–57, 2003. © 2002 Wiley‐Liss, Inc.
Seismic isolation of civil buildings in Armenia
Authors: Melkumyan M G
Published: December 2002

Since 1994 a total of 24 buildings and structures have been designed in Armenia that incorporate seismic isolation bearings. The number of base‐ and roof‐isolated buildings already constructed in Armenia has reached 14. Currently, several base‐isolated buildings are under construction. Seismic isolation systems and justification of their effectiveness and application in Armenia are given in this paper. Statistics and examples characterizing various types of applications of seismic isolation techniques are described. The development of a design code and design guidelines for seismic isolation of buildings and structures is discussed. A new concept of a dynamic damper to restrict the displacements of seismic isolated buildings is presented, and future applications of seismic isolation techniques are mentioned.
Progress in the application of active vibration control technologies to long‐span bridges in Japan
Authors: Tanida Koji
Published: December 2002

Vibration of long‐span bridges can be caused by various types of dynamic excitation, wind‐induced vibration may be the most critical for long‐span bridges such as suspension bridges and cable‐stayed bridges. Typical example are pylons, and wind induced vibration of these during erection affects the safety serviceability of the structure. Formerly, sliding‐block dampers using wires were installed to reduce wind‐induced vibration of pylons, but these had the defects of requiring large space for installation, and there were difficulties with evaluation of damping effects. For the past 15 years, passive‐type tuned mass dampers or tuned liquid dampers have become popular in Japan, but as natural frequencies of pylons vary widely according to the height of pylons during erection, several sets of mass dampers of different natural frequencies have to be prepared. To overcome these drawbacks of passive type mass dampers, actively controlled mass dampers have been developed to reduce the vibration of various modes of structures. The pylons of the Rainbow Suspension Bridge in Tokyo incorporated the first application of the active control system in the world in 1991. The results of active control were found to be very effective, and its technologies have already been applied to more than 10 pylons of long‐span bridges in Japan. This paper reviews progress in the application of active vibration control technologies to long‐span bridges in Japan.
Progress of applications of active vibration control for buildings in Japan
Authors: Fujita Takafumi
Published: December 2002

In Japan, applications of active/hybrid mass dampers have steadily progressed since the first application in 1989. Particularly, applications of hybrid mass dampers with convertible active and passive modes have recently progressed because their effectiveness has been gradually recognized by many structural engineers. This paper overviews the progress of applications of active/hybrid mass dampers, and describes merits of the hybrid mass dampers.
Status of structural health monitoring of long‐span bridges in the United States
Authors: Pines Darryll , Aktan A Emin
Published: December 2002

This paper gives an overview of ongoing research and development in the field of structural health monitoring technologies in the US, with application to long‐span bridges. Specifically, this paper attempts to review various key structural health monitoring technologies, including sensor development, data processing, damage detection algorithms, data analysis and information processing. Several examples are cited from the aerospace, civil and mechanical communities. Monitoring of constructed systems are of considerable interest since the consequences of failure can have a significant effect on the society at large. For instance, consider the 1100 major long‐span bridges in the USA (those with spans of 100 m or longer), many are over 50 years old, and several notable ones are over 100 years old. These bridges fall outside the Standard Specifications issued by AASHTO (1998), and there is little generic experience related to maintaining their performance, especially after they age and/or following any damage. More than 800 of the long‐span bridges in the National Bridge Inventory are classified as fracture‐critical. It follows that structural health monitoring techniques may prove to be useful for maintaining and preserving this population of aging civil infrastructure. It is hoped that the following will stimulate additional discussion regarding the importance of structural health monitoring as an emerging research area for a variety of aerospace, civil and mechanical applications.
Dynamic response of structures to thunderstorm winds
Authors: Choi Edmund CC , Hidayat Ferry A
Published: December 2002

A study of the dynamic response of structure to different types of wind is reported in this paper. Response to large‐scale (monsoon wind) and small‐scale winds (thunderstorm) of a SDOF structure is investigated. The monsoon wind is observed to be relatively stationary, and structure response predicted by the gust response factor (GRF) method is reasonably accurate. However, for thunderstorm events, the wind processes are observed to be non‐stationary, and predictions using GRF method very much under‐estimate the actual response.

A modification to the GRF method is proposed for thunderstorm winds whereby a running‐mean procedure is introduced. The fluctuation about the running‐mean is observed to be more stationary. The result obtained from the running‐mean GRF method is more accurate. For the thunderstorm events studied, the best predictions are obtained for a running‐mean period of around 60 s.
Three‐dimensional continuum finite element models for plate/shell analysis
Authors: Sze K Y
Published: December 2002

In the last one and a half decades, a considerable amount of three‐dimensional continuum finite element models have been proposed for plate/shell analysis. These continuum elements possess no rotational degree of freedom and are sometimes known as solid‐shell elements. Development of solid‐shell elements is not straightforward. To be applicable to thin‐ and curved‐shell analysis, element deficiencies known as shear, membrane, trapezoidal and thickness lockings must be envisioned. To alleviate or resolve them, advanced finite element techniques, including reduced integration, stabilization, assumed natural strain, enhanced assumed strain, hybrid strain and hybrid stress methods, have been resorted to. This article aims to provide a review of past efforts at formulating reliable solid‐shell elements.
Smart and designer structural material systems
Authors: Chong Ken P , Garboczi Edward J
Published: December 2002

An efficient civil infrastructure system is essential to every country's productivity, security, and quality of life. Basic research and development in smart structures and designer materials have shown great potential for enhancing the functionality, serviceability, and increased lifespan of civil infrastructure systems. New construction and the intelligent renewal of ageing and deteriorating civil infrastructure systems include efficient and innovative use of high‐performance designer materials, sensors, actuators, and mechanical and structural systems. High‐performance designer materials, in particular, require new methods of computational materials science, some of which are described herein. In this paper, some examples of National Science Foundation (NSF) funded awards, some examples of National Institute of Standards and Technology (NIST) ‘designer material’ projects, and future research needs, as well as new research initiatives on nanotechnology, are presented.
Finite element mesh generation and adaptive meshing
Authors: Lo S H
Published: December 2002

This review paper gives a detailed account of the development of mesh generation techniques on planar regions, over curved surfaces and within volumes for the past years. Emphasis will be on the generation of the unstructured meshes for purpose of complex industrial applications and adaptive refinement finite element analysis. Over planar domains and on curved surfaces, triangular and quadrilateral elements will be used, whereas for three‐dimensional structures, tetrahedral and hexahedral elements have to be generated. Recent advances indicate that mesh generation on curved surfaces is quite mature now that elements following closely to surface curvatures could be generated more or less in an automatic manner. As the boundary recovery procedure are getting more and more robust and efficient, discretization of complex solid objects into tetrahedra by means of Delaunay triangulation and other techniques becomes routine work in industrial applications. However, the decomposition of a general object into hexahedral elements in a robust and efficient manner remains as a challenge for researchers in the mesh generation community. Algorithms for the generation of anisotropic meshes on 2D and 3D domains have also been proposed for problems where elongated elements along certain directions are required. A web‐site for the latest development in meshing techniques is included for the interested readers.
Competitive positioning within and across a strategic group structure: the performance of core, secondary, and solitary firms
Authors: McNamara Gerry , Deephouse David L. , Luce Rebecca A.
Published: December 2002

Drawing from economic and cognitive theories, researchers have argued that firms within an industry tend to cluster together, following similar strategies. Their positioning in strategic groups, in turn, is argued to influence firm actions and firm performance. We extend this research to examine performance implications of competitive positioning not just among but also within groups. We find that performance differences within groups are significantly larger than across groups, suggesting that some firms within groups develop better resource or competitive positions. We also find that secondary firms within a group outperform both core firms within the group and solitary firms, the latter being those not belonging to any multifirm strategic group. This suggests that secondary firms may be able to effectively balance the benefits of strategic distinctiveness with institutional pressures for similarity. We conclude that the primary implication of strategic groups does not relate to the ability of firms to create stable, advantageous market segments through collusion. Instead, strategic groups represent a range of viable strategic positions firms may stake out and use as reference points. Moreover, our results concerning secondary firms indicate that firm positioning within a group structure can have performance implications. Copyright © 2002 John Wiley & Sons, Ltd.
Empirical studies of test‐suite reduction
Authors: Rothermel Gregg , Harrold Mary Jean , von Ronne Jeffery , Hong Christie
Published: December 2002

Test‐suite reduction techniques attempt to reduce the costs of saving and reusing test cases during software maintenance by eliminating redundant test cases from test suites. A potential drawback of these techniques is that reducing the size of a test suite might reduce its ability to reveal faults in the software. Previous studies have suggested that test‐suite reduction techniques can reduce test‐suite size without significantly reducing the fault‐detection capabilities of test suites. These studies, however, involved particular programs and types of test suites, and to begin to generalize their results, further work is needed. This paper reports on the design and execution of additional studies, examining the costs and benefits of test‐suite reduction, and the factors that influence these costs and benefits. In contrast to previous studies, results of these studies reveal that the fault‐detection capabilities of test suites can be severely compromised by test‐suite reduction. Copyright © 2002 John Wiley & Sons, Ltd.