bluuebunny/crossref_metadata_2025 huggingface dataset:
On the classical shell model underlying bilinear degenerated shell finite elements
Authors: Malinen Mika
Published: August 2002

We study the shell models arising in the numerical modelling of shells by bilinear degenerated shell finite elements. The numerical model of a cylindrical shell obtained by using flat shell elements is given an equivalent formulation based on a classical two‐dimensional shell model. We use the connection between the models to explain how a parametric error amplification difficulty or locking is avoided by some elements. Copyright © 2001 John Wiley & Sons, Ltd.
A Galerkin/least‐squares finite element formulation for consolidation
Authors: Truty A.
Published: August 2002

A Galerkin/least‐squares (GLS) finite element formulation for problem of consolidation of fully saturated two‐phase media is presented. The elimination of spurious pressure oscillations appearing at the early stage of consolidation for standard Galerkin finite elements with equal interpolation order for both displacements and pressures is the goal of the approach. It will be shown that the least‐squares term, based exclusively on the residuum of the fluid flow continuity equation, added to the standard Galerkin formulation enhances its stability and can fully eliminate pressure oscillations. A reasonably simple framework designed for derivation of one‐dimensional as well as multi‐dimensional estimates of the stabilization factor is proposed and then verified. The formulation is validated on one‐dimensional and then on two‐dimensional, linear and non‐linear test problems. The effect of the fluid incompressibility as well as compressibility will be taken into account and investigated. Copyright © 2001 John Wiley & Sons Ltd.
Efficient computation of order and mode of corner singularities in 3D‐elasticity
Authors: Dimitrov A. , Andrä H. , Schnack E.
Published: August 2002

A general numerical procedure is presented for the efficient computation of corner singularities, which appear in the case of non‐smooth domains in three‐dimensional linear elasticity. For obtaining the order and mode of singularity, a neighbourhood of the singular point is considered with only local boundary conditions. The weak formulation of the problem is approximated by a Galerkin–Petrov finite element method. A quadratic eigenvalue problem (P+λQ+λ2R) u=0 is obtained, with explicitly analytically defined matrices P,Q,R. Moreover, the three matrices are found to have optimal structure, so that P,R are symmetric and Q is skew symmetric, which can serve as an advantage in the following solution process. On this foundation a powerful iterative solution technique based on the Arnoldi method is submitted. For not too large systems this technique needs only one direct factorization of the banded matrix P for finding all eigenvalues in the interval ℛe(λ)∈(−0.5,1.0) (no eigenpairs can be ‘lost’) as well as the corresponding eigenvectors, which is a great improvement in comparison with the normally used determinant method. For large systems a variant of the algorithm with an incomplete factorization of P is implemented to avoid the appearance of too much fill‐in. To illustrate the effectiveness of the present method several new numerical results are presented. In general, they show the dependence of the singular exponent on different geometrical parameters and the material properties. Copyright © 2001 John Wiley & Sons, Ltd.
Hypersingular boundary integral equation for axisymmetric elasticity
Authors: de Lacerda L. A. , Wrobel L. C.
Published: August 2002

An axisymmetric hypersingular boundary integral formulation for elasticity problems is presented in this paper. The hypersingular and strong‐singular fundamental solutions are derived and their singular behaviour is discussed in detail for different locations of the source point. Several free terms arise from the limiting process when generating hypersingular boundary integral equations, including an extra one specific to the axisymmetric formulation which does not appear in two and three dimensional cases. The singularity subtraction technique is used to regularize all strong‐singular and hypersingular integrals, and their evaluation procedure is explained. Finally, the developed formulation is assessed through simple numerical tests. Copyright © 2001 John Wiley & Sons, Ltd.
Archaeological analysis of shell middens in the Beagle Channel, Tierra del Fuego Island
Authors: Estevez Jordi , Piana Ernesto , Schiavini Adrian , Juan‐Muns Nuria
Published: August 2002

An archaeological programme beginning in 1993, in the Beagle Channel, aims to describe the long‐term record of maritime faunal exploitation, and relate it to the environmental record. Results from quantitative analysis of remains from a series of shell midden excavations indicate a remarkably stable and resilient marine biota over the last 6500 years. Only in the previous century have there been changes in fauna, which might correspond to recent global warming. Copyright © 2001 John Wiley & Sons, Ltd.
Viking age horse graves from Kaunas region (Middle Lithuania)
Authors: Bertašius M. , Daugnora L.
Published: August 2002

Balts' territories have one peculiarity—large amounts of horse bones are found in burial grounds. This phenomenon is typical to the Prussians (5th–11th centuries) and Lithuanians (Kaunas region 8th–11th centuries)

Horse burials of the 8th–11th centuries reflect the archaeological culture of Middle Lithuania most significantly.

Several horse burial types have been defined on the basis of individuals; osteological signs and the archaeological data of the horse remains. A typical horse grave is when the whole horse was buried. Sometimes only a head or a head with forelegs, or scattered horse remains are found in a burial. The large number of burial grounds with an abundance of horse graves testifies to a very expressive ritual of horse offering in the Balts' region.

On the basis of the data obtained, we determined that mostly 4–10 year old horses were buried in the grounds of Middle Lithuania.

From the bone measurements, it has been determined that the length of metacarpals ranges between 180 and 216 mm (the average length 193.1±0.99 mm); the length of metatarsals between 218 and 253 mm (average length 233.9±0.73 mm).These data demonstrate that horses of different types were buried in Marvelė and Veršvai burial grounds (wither height 120–136 cm). A certain number of the larger horses (wither height 136–144 and 153 cm; length of metacarpals 210–222 mm) might not have belonged to local breeds.

We have come to the conclusion that the most similar horse skeletons (according to the osteometric data) were found in Latvia. Copyright © 2001 John Wiley & Sons, Ltd.
Performance appraisal in the Maldives public service: challenges and issues
Authors: Asim Mohamed
Published: August 2002

A structured method of evaluating and rewarding the performance of employees in the Maldives public service did not exist before 1996. Personnel decisions, such as employee promotions, were subjective and based merely on the recommendation of the heads of departments. Hence, in 1996, the Government of Maldives introduced a performance appraisal system, based on rewarding employees through the assessment of several factors such as quality of work, job knowledge and performance. The reward came in the form of annual salary increments. In reviewing this system, the article finds that human resource units or divisions within departments now need to be strengthened for the effective implementation of the system; more training has to be provided to public service employees in terms of raising their awareness as to the objectives of the performance appraisal exercise; and the performance appraisal framework needs to be more flexible in differentiating very high performers, at the same time devising a strategy for the improvement of employees who slack in performance. Copyright © 2001 John Wiley & Sons, Ltd.
Preparation and characterization of polyaniline blends with polyvinyl acetate, polystyrene and polyvinyl chloride for toxic gas sensors
Authors: Hosseini S. Hossein , Entezami Ali A.
Published: August 2002

The conditions of processing and gas sensing of ­polyaniline (PANi) blends with polyvinyl acetate (PVAc), polystyrene (PS) and polyvinyl chloride (PVC) were investigated. Flexible, free‐standing and stretchable films of various blends compositions were obtained by casting. The mechanisms of the conducting blends response to a selection of gases and vapours were investigated using two techniques: measurement of conductance and mass changes using a four‐point probe method and X‐ray fluorescence (XRF) device, respectively. These responses to toxic gases and vapours are better explained by polymer blends than homopolymers. Prepared films were exposed to hydrogen halides, hydrogen cyanide, halogens, monochloroacetic acid (MCAA), 1‐3‐5 trichloromethyl benzene (TCMB), methylbenzyl bromide (MBB), bromoacetone (BA) and cyanogen bromide (CB). The changes in conductivity of various polymer frequently observed are partly due to one stage in the two‐stage sorption perhaps involving the swelling of the polymer and then diffusion of gases into polymer chains. The swelling of polymers is a slow process, therefore, we have pre‐swelled polymer films which tend to decrease the response times of blends in respect to gases. The structures of the blends are examined by STA (TGA & DSC) and SEM studies. Copyright © 2001 John Wiley & Sons, Ltd.
Improving cell affinity of ­poly(D,L‐lactide) film modified by anhydrous ammonia plasma treatment
Authors: Yang Jian , Bei Jianzhong , Wang Shenguo
Published: August 2002

Anhydrous ammonia gaseous plasma treatment was used for improving cell affinity of the poly(D,L‐lactide) film surface. The contact angle was measured and the surface energy was calculated through harmonic mean equations. The surface chemical composition of the sample was identified by X‐ray photoelectron spectroscopy (XPS) analysis. It was demonstrated that the O‐containing and N‐containing groups such as hydroxyl and amine were incorporated onto the surface of films. The effect of preserving methods for maintaining the hydrophilicity was also investigated. The result indicated that preserving at low temperature (0–4 °C) was sufficient to maintain the improvements. It could resolve the problem of hydrophilicity being partially lost with preserving time after plasma treatment. Mouse 3T3 fibroblast cells were used as model cells to compare the cell affinity of the modified films and control. The ammonia plasma treatment could promote the cells attachment and cells growth. After 4 days culture, the plasma treated films yielded almost two magnitude cells compared with the control. Copyright © 2002 John Wiley & Sons, Ltd.
Integrin up‐regulation in chronic liver disease: relationship with inflammation and fibrosis in chronic hepatitis C
Authors: Nejjari Mimoun , Couvelard Anne , Mosnier Jean‐François , Moreau Alain , Feldmann Gérard , Degott Claude , Marcellin Patrick , Scoazec Jean‐Yves
Published: August 2002

In 94 patients with chronic hepatitis C, the pattern of integrin expression was correlated with firstly, the histological activity index, necro‐inflammatory grade, and stage of fibrosis; secondly, the expression of inflammatory markers including ICAM‐1; and thirdly, the extent and intensity of laminin deposition in the perisinusoidal matrix. Immunohistochemical results were evaluated according to a semi‐quantitative scoring system or by image analysis. Increased β1 expression was observed in 88.2% of cases. The expression of α1 and α5 was increased in 55% and 58.5% of cases, respectively. α6 chain was detected in 78.7% of cases. There were no statistically significant differences in integrin expression level according to Knodell's score, inflammatory grade, or stage of fibrosis. ICAM‐1 expression was higher in patients with high scores for β1 expression, but the differences were not statistically significant. There were significantly more patients with high scores for β1 expression among those with continuous perisinusoidal deposition of laminin. Moreover, a close statistical correlation was observed between α6 induction and perisinusoidal laminin deposition (p<0.001). The results suggest that integrin up‐regulation in chronic hepatitis C is more closely related to the fibrotic process than to the inflammatory lesions. This reinforces the idea that integrin induction in chronic liver disease is part of a coordinated process involved in the progression of liver fibrosis. Copyright © 2001 John Wiley & Sons, Ltd.
‘Diabetic holiday foot syndrome’: a preventable complication†
Authors: Stanaway S.E.R.S. , Gill G.V. , Kaczmarcyk Edward , Kaye Linda
Published: August 2002

Foot ulceration in diabetic patients is a serious complication, with the potentially devastating possibility of lower limb amputation. We describe six patients with type 2 diabetes who all developed significant neuropathic foot ulceration during holidays, mostly in hot countries abroad. All were male, aged 52–62, and one patient developed three ulcers on the same foot on three consecutive holidays, the last one resulting in a below knee amputation. The specific causes of ulceration were often related to walking barefoot (on sand, shingle or hot flagstones), or wearing inadvisable beach footwear. The association of poor educational compliance and a high‐risk environment may lead to this specific ‘diabetic holiday foot syndrome’. Intensive warning education prior to at‐risk patients going on holiday may help prevent this serious complication. Copyright © 2001 John Wiley & Sons, Ltd.
Adverse drug events in hospitalized patients treated with cardiovascular drugs and anticoagulants
Authors: Zaidenstein R. , Eyal S. , Efrati S. , Akivison L. , Koren Michowitz M. , Nagornov V. , Golik A.
Published: August 2002

Purpose

To evaluate the incidence of serious adverse drug events (ADEs) caused by cardiovascular drugs during hospitalization in a department of internal medicine, and to identify patients at highest risk.

Patients and methods

All the patients treated with cardiovascular drugs and/or anticoagulants in the department between November 1999 and January 2000 were recruited into the study. During hospitalization the patients' charts were reviewed by a pharmacist and a clinician, and the occurrence of serious ADEs was assessed using the Naranjo algorithm. ‘Possible’ and ‘doubtful’ ADEs were not counted.

Results

Of 496 patients who were enrolled in the study, 20 (4%) had serious ADEs. Compared to patients without ADEs, patients in the ADE group were older (72 ± 12.6 years (mean ± SD) vs. 65 ± 13 years, p = 0.048), their average stay in hospital was longer (7.3 ± 5.5 days vs. 5.2 ± 3.7 days, p = 0.018) and their mean urea levels were higher (10.8 ± 9.3 mmol/l vs. 7.8 ± 5.3 mmol/l, p = 0.027). The most frequent background pathologies of the 20 patients with ADEs were hypertension (in 18 (90%)) and atrial fibrillation (in nine (45%)). In 50% of the the ADE group there was a history of drug allergies. The ADEs recorded were bleeding in four (20%), arrhythmias in six (30%), orthostatic hypotension in six (30%) and skin necrosis, paranoid reaction, acute hepatitis and acute renal failure in four (20%). The causative drugs were warfarin (which accounted for 25% of the ADEs), beta‐blockers (15%), propafenone (5%), amiodarone (5%), and Ca2+‐channel blockers, nitrates and diuretics (together accounting for 50% of ADEs). Drug combinations were implicated in 50% of ADE.

Conclusions

Serious ADEs were developed by 4% of hospitalized patients taking cardiovascular drugs. Those at highest risk were older, were receiving multiple drug therapy and had higher urea levels. Warfarin and beta‐blockers were the drugs causing the largest number of adverse effects . ADEs are an important cause of preventable morbidity, often with serious economic implications and special attention should be given to their prevention. Copyright © 2002 John Wiley & Sons, Ltd.
Controlled release of aminophylline from poly (N‐isopropylacrylamide‐co‐itaconic acid) hydrogels
Authors: Katime Issa , Valderruten Nora , Quintana José R
Published: August 2002

N‐Isopropylacrylamide (NIPA) has been copolymerized with itaconic acid (IA) in the presence of N,N‐methylenebisacrylamide (BIS) as crosslinker. The swelling capacity and the release rate of aminophylline at 37 °C are reported. Maximum equilibrium swelling increases as the itaconic acid content in the hydrogel increases. The experimental data suggest clearly that the swelling process obeys second‐order kinetics. According to this, the kinetic constant, k, and the maximum equilibrium swelling, W∞, have been calculated. Drug release from fully swollen hydrogels follows Fick's law closely, but deviates from it for xerogels.

© 2001 Society of Chemical Industry
Dye‐affinity hollow‐fibres and their lysozyme adsorption–desorption characteristics
Authors: Şenel Serap , Akgöl Sinan , Arica Yakup , Denizli Adil
Published: August 2002

Dye‐affinity adsorption is increasingly used for protein separation. Hollow‐fibres have advantages as adsorbents in comparison to conventional bead supports because they are not compressible and can eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of polyamide hollow‐fibres to which Reactive Green HE‐4BD was attached for adsorption of lysozyme. The hollow‐fibre was characterized by scanning electron microscopy. These dye‐carrying hollow‐fibres (26.3 µmol g−1) were used in the lysozyme adsorption–elution studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye‐attached hollow‐fibres was studied in a batch system. The non‐specific adsorption of lysozyme on the polyamide hollow‐fibres was 1.8 mg g−1. Reactive Green HE‐4BD attachment significantly increased the lysozyme adsorption up to 41.1 mg g−1. Langmuir adsorption model was found to be applicable in interpreting lead adsorption by Reactive Green HE‐4BD attached hollow fibres. Significant amount of the adsorbed lysozyme (up to 95%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pH 8.0. In order to determine the effects of adsorption conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We concluded that polyamide dye‐affinity hollow‐fibres can be applied for lysozyme adsorption without causing any significant conformational changes. Repeated adsorption–elution processes showed that these dye‐attached hollow‐fibres are suitable for lysozyme adsorption.

© 2001 Society of Chemical Industry
Synthesis, characterization and crosslinking of functional star‐shaped poly(ε‐caprolactone)
Authors: Turunen Markus P K , Korhonen Harri , Tuominen Jukka , Seppälä Jukka V
Published: August 2002

Star‐shaped low molecular weight poly(ε‐caprolactone)s (PCLs) were synthesized and functionalized with crosslinkable terminal groups for subsequent crosslinking. The ε‐caprolactone (CL) prepolymers were polymerized by ring‐opening in the presence of polyglycerine (PGL) as an initiator (1, 3 and 5 mol%) and Sn(II)2‐ethylhexanoate as a catalyst. Characterization of the prepolymer by 13C/1H nuclear magnetic resonance (NMR) spectroscopy, size exclusion chromatography (SEC), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) revealed a six‐armed star‐shaped structure for the prepolymer with the molecular weight controlled by the ratio of PGL and CL. Functionalization of the hydroxyl‐terminated prepolymer was carried out with maleic or itaconic anhydride. In both cases, the characterization of the functionalized prepolymer showed that the hydroxyl groups were completely substituted. The functionalized PCLs were successfully crosslinked through the reaction of double bonds. The crosslinking was induced either thermally with organic peroxide or photochemically with a photosensitive initiator. Characterization of the crosslinked PCLs by Soxhlet extraction, DSC and FTIR showed that the itaconic double bond was much more reactive in thermal crosslinking than the maleic double bond. Thus, the crosslinked prepolymers that were functionalized with itaconic double bonds achieved a gel content of about 90%. A gel content of 100% was achieved with several compositions where crosslinking agents were employed.

© 2002 Society of Chemical Industry
New poly(arylene ether)s with pendant phosphonic acid groups
Authors: Miyatake Kenji , Hay Allan S.
Published: August 2002

Soluble brominated poly(arylene ether)s containing mono‐ or dibromotetraphenylphenylene ether and octafluorobiphenylene units were synthesized. The polymers were high molecular weight (weight‐average molecular weight = 115,100–191,300; number‐average molecular weight = 32,300–34,000) and had high glass‐transition temperatures (>279 °C) and decomposition temperatures (>472 °C). The brominated polymers were phosphonated with diethylphosphite by a palladium‐catalyzed reaction. Quantitative phosphonation was possible when 50 mol % of a catalyst based on bromine was used. The diethylphosphonated polymers were dealkylated by a reaction with bromotrimethylsilane in carbon tetrachloride followed by hydrolysis with hydrochloric acid. The polymers with pendant phosphonic acid groups were soluble in polar solvents such as dimethyl sulfoxide and gave flexible and tough films via casting from solution. The polymers were hygroscopic and swelled in water. They did not decompose at temperatures of up to 260 °C under a nitrogen atmosphere. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3770–3779, 2001
Stability of photocurable anhydrides: Methacrylic acid mixed anhydrides of nontoxic diacids
Authors: Tarcha Peter J. , Su Lin , Baker Tom , Langridge Denton , Shastri Venkatram , Langer Robert
Published: August 2002

Disproportionation of the liquid mixed anhydride dimethacrylic sebacic anhydride (m‐SA) to methacrylic anhydride and polyanhydride oligomers, as well as vinylic polymerization, can occur on workup and storage at room temperature. Dimethacrylic 1,3‐bis(p‐carboxyphenoxy) propane, being a solid, can also disproportionate, but the propensity to do so is lower than for m‐SA. These events can be suppressed with free‐radical inhibitors, and the inhibitor 2+3‐t‐butyl‐4‐methoxyphenol is a more effective stabilizer than 4‐methoxyphenol at 20 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4189–4195, 2001
Synthesis and characterization of novel aliphatic polycarbonates
Authors: Wang Xu‐Li , Zhuo Ren‐Xi , Liu Li‐Jian , He Feng , Liu Gang
Published: August 2002

A new six‐membered cyclic carbonate monomer, 5‐benzyloxy‐trimethylene carbonate, was synthesized from 2‐benzyloxy‐1,3‐propanediol, and the corresponding polycarbonate, poly(5‐benzyloxy‐trimethylene carbonate) (PBTMC), was further synthesized by ring‐opening polymerization in bulk at 150 °C using aluminum isobutoxide [Al(OiBu)3], aluminum isopropoxide, or stannous octanoate as an initiator. The results showed that a higher molecular weight polycarbonate could be obtained in the case of Al(OiBu)3. The protecting benzyl group was removed subsequently by catalytic hydrogenation to give a polycarbonate containing a pendant hydroxyl group (PHTMC). The polycarbonates obtained were characterized by Fourier transform infrared spectroscopy, 1H NMR,13C NMR, gel permeation chromatography, and DSC. NMR results of PBTMC offered no evidence for decarboxylation occurring during the propagation. The pendant hydroxyl group in PHTMC resulted in an enhancement of the hydrophilicity of the polycarbonate. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 70–75, 2002
Method for grafting poly(acrylic acid) onto nylon 6,6 using amine end groups on nylon surface
Authors: Tobiesen Finn Andrew , Michielsen Stephen
Published: August 2002

Several methods have been developed for grafting materials to the surface of polymers to alter their surface characteristics. This article reports a procedure for grafting poly(acrylic acid) (PAA) onto nylon 6,6 films via the naturally occurring amine end groups of nylon 6,6 using N‐hydroxy‐succinimide in conjunction with 1‐ethyl‐3‐ (3‐dimethylaminopropyl)carbodiimide hydrochloride (EDC) facilitated amidazation. Reaction conditions were investigated with respect to PAA molecular weight, activator concentrations, reaction temperature, and time. X‐ray photoelectron spectroscopy showed that surface coverage of more than 50% was consistently achieved for 250 kD PAA. The maximum grafting occurred at room temperature with a large excess of EDC with a reaction time of 30 min. The same level of grafting can be achieved using smaller amounts of EDC at 60 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 719–728, 2002; DOI 10.1002/pola.10149
Synthesis and structural analysis of functionalized poly (ϵ‐caprolactone)‐based three‐arm star polymers
Authors: Lang Meidong , Wong Renee Puisan , Chu Chih‐Chang
Published: August 2002

Hydroxyl‐functionalized three‐arm poly(ϵ‐caprolactone)s (PGCL‐OHs) were synthesized by the ring‐opening polymerization of ϵ‐caprolactone in the presence of glycerol (as the core) and stannous octoate. The effect of the feed ratio of ϵ‐caprolactone to glycerol on the ring‐opening polymerization was studied. These three‐arm PGCL‐OHs were then converted into double‐bond‐functionalized three‐arm poly(ϵ‐caprolactone)s (PGCL‐Mas) by the reaction of PGCL‐OH with maleic anhydride in the melt at 130 °C. The quantitative conversion of hydroxyl functionality was achieved at a low molecular weight. The resulting PGCL‐OH and PGCL‐Ma were characterized with gel permeation chromatography, Fourier transform infrared, 1H NMR, 13C NMR, and differential scanning calorimetry. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1127–1141, 2002
Synthesis and properties of polyimides derived from 9,10‐dialkyloxy‐1,2,3,4,5,6,7,8‐octahydro‐2,3,6,7‐anthracenetetracarboxylic 2,3:6,7‐dianhydrides
Authors: Kim Yong Seok , Jung Jin Chul
Published: August 2002

A series of new polyimides containing alicyclic units and alkyloxy side chains were prepared from 9,10‐dialkyloxy‐1,2,3,4,5,6,7,8‐octahydro‐2,3,6,7‐anthracenetetracarboxylic 2,3:6,7‐dianhydrides and various aromatic diamines. Their physical properties and structures were investigated. Polymers were obtained with inherent viscosities of 0.24–0.53 dL/g. In comparison with the aromatic polyimides, most polymers were readily soluble in common organic solvent such as N‐methylpyrrolidone and m‐cresol. These polymers had glass‐transition temperatures between 111 and 296 °C depending on the structure of the repeating unit and 10% weight‐loss temperatures of 418–477 °C in nitrogen. Wide‐angle X‐ray diffractometry for as‐polymerized samples revealed very low crystallinity and layered structures, which were better developed in the polymers with longer side chains. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1764–1774, 2002
Synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] by incorporation of carbon dioxide into epoxide polymer and the miscibility behavior of its blends with poly(methyl methacrylate) or poly(vinyl chloride)
Authors: Park Sung‐Young , Park Hee‐Young , Lee Hwa‐Soo , Park Sang‐Wook , Ha Chang‐Sik , Park Dae‐Won
Published: August 2002

This study was related to the investigation of the chemical fixation of carbon dioxide to a copolymer bearing epoxide and the application of the cyclic carbonate group containing copolymer‐to‐polymer blends. In the synthesis of poly[(2‐oxo‐1,3‐dioxolane‐4‐yl) methyl methacrylate‐co‐ethyl acrylate] [poly(DOMA‐co‐EA)] from poly(glycidyl methacrylate‐co‐ethyl acrylate) [poly(GMA‐co‐EA)] and CO2, quaternary ammonium salts showed good catalytic activity. The films of poly(DOMA‐co‐EA) with poly(methyl methacrylate) (PMMA) or poly(vinyl chloride) (PVC) blends were cast from N,N′‐dimethylformamide solution. The miscibility of the blends of poly(DOMA‐co‐EA) with PMMA or PVC have been investigated both by DSC and visual inspection of the blends. The optical clarity test and DSC analysis showed that poly(DOMA‐co‐EA) containing blends were miscible over the whole composition range. The miscibility behaviors were discussed in terms of Fourier transform infrared spectra and interaction parameters based on the binary interaction model. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1472–1480, 2001
Star‐shaped fluorescent polypeptides
Authors: Klok Harm‐Anton , Hernández Juan Rodríguez , Becker Stefan , Müllen Klaus
Published: August 2002

Two series of novel, four‐arm, star‐shaped polypeptides were prepared via the ring‐opening polymerization of γ‐benzyl‐L‐glutamate N‐carboxyanhydride and ϵ‐benzyloxycarbonyl‐L‐lysine N‐carboxyanhydride with a tetra‐amino‐substituted perylene fluorophore as the initiator. The removal of the α‐amino acid side‐chain‐protecting groups resulted in unprecedented water‐soluble, perylene‐functionalized, star‐shaped polypeptides that showed strong fluorescence in aqueous solution. One of the features that distinguished these water‐soluble star polypeptides from most other star polymers was that the conformation of the arms could be reversibly changed from a random coil into an α helix by variations in the pH of the aqueous solution. These star polypeptides might be of interest for the development of novel fluorescent probes or as traceable, stimuli‐sensitive molecular containers. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1572–1583, 2001
Synthesis and characterization of nonaqueous dispersion particles with photolabile α‐heptadecylphenacyl ester stabilizer chains
Authors: Zhou Chunlin , Winnik Mitchell A. , Jao Tze‐Chi
Published: August 2002

We describe a new method for the synthesis of core–shell photolabile nanoparticles. The synthesis begins with the batch emulsion copolymerization of n‐butyl methacrylate (BMA) and ethylene glycol dimethacrylate to form small (20‐nm‐diameter) crosslinked particles with a narrow size distribution. These seeds are then used for a second‐stage emulsion copolymerizations in which BMA and various polar monomers, including methacrylic acid, are added under monomer‐starved conditions. After characterization of the particles, they are transferred to an N,N‐dimethylformamide solution. The cesium salt of the carboxylic acid groups is reacted with 2‐bromo‐1‐phenyl‐octadecan‐1‐one to convert various fractions of the COOH groups to the corresponding 2‐benzoylheptadecyl ester groups. These aliphatic ester groups render the surface sufficiently hydrophobic that the particles can be dispersed in common aliphatic hydrocarbons solvents to yield colloidal dispersions, sterically stabilized by the dangling aliphatic chains. Ester groups with a phenyl ketone attached to the β‐carbon are photolabile. Irradiation of the particles with UV light detaches the sterically stabilizing chains from the particle and transforms the surface groups back to COOH groups. This leads to flocculation of the particles. The emphasis in this article is on the optimization of the particle synthesis and the characterization of the particles obtained. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2642–2657, 2001
Stereospecific and molecular weight‐controlled polymerization of 1,3‐butadiene with Co(acac)3‐MAO catalyst
Authors: Endo Kiyoshi , Hatakeyama Naoyoshi
Published: August 2002

The polymerization of butadiene (Bd) with Co(acac)3 in combination with methylaluminoxane (MAO) was investigated. The polymerization of Bd with Co(acac)3‐MAO catalysts proceeded to give cis‐1,4 polymers (94 – 97%) bearing high molecular weights (40 × 104) with relatively narrow molecular weight distributions (Mw's/Mn's). The molecular weight of the polymers increased linearly with the polymer yield, and the line passed through an original point. The polydispersities of the polymers kept almost constant during reaction time. This indicates that the microstructure and molecular weight of the polymers can be controlled in the polymerization of Bd with the Co(acac)3‐MAO catalyst. The effects of reaction temperature, Bd concentration, and the MAO/Co molar ratio on the cis‐1,4 microstructure and high molecular weight polymer in the polymerization of Bd with Co(acac)3‐MAO catalyst were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2793–2798, 2001
Polyfluorenes: Twenty years of progress
Authors: Leclerc Mario
Published: August 2002

Polyfluorenes are an important class of electroactive and photoactive materials. In the last three years this research field has literally exploded because of polyfluorenes' exceptional electrooptical properties for applications in light‐emitting diodes. This is the only family of conjugated polymers that emit colors spanning the entire visible range with high efficiency and low operating voltage. Other unusual optical and electrical properties are made possible with polyfluorene derivatives, such as thermochromism and conducting base‐doped polyelectrolytes. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2867–2873, 2001
Synthesis of polyethylene hybrid copolymers containing polyhedral oligomeric silsesquioxane prepared with ring‐opening metathesis copolymerization
Authors: Zheng Lei , Farris Richard J. , Coughlin E. Bryan
Published: August 2002

Ring‐opening metathesis copolymerizations of cyclooctene and the polyhedral oligomeric silsesquioxane (POSS) monomer 1‐[2‐(5‐norbornen‐2‐yl)ethyl]‐3,5,7,9,11,13,15‐heptacyclopentylpentacyclo[9.5.1.13,9.15,15.17,13] octasiloxane (POSS–norbornylene) were performed with Grubbs's catalyst, RuCl2(CHPh)(PCy3)2. Random copolymers were formed and fully characterized with POSS loadings as high as 55 wt %. Diimide reduction of these copolymers afforded polyethylene–POSS random copolymers. Thermogravimetric analysis of the polyethylene–POSS copolymers under air showed a 70 °C improvement, relative to a polyethylene control sample of similar molecular weight, in the onset of decomposition temperature based on 5% mass loss. The homopolymer of POSS–norbornylene was also synthesized. This polymer had a rigid backbone according to 1H NMR evidence of broad olefinic signals. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2920–2928, 2001
Synthesis and characterization of alternating copolymers containing triphenylamine as hole‐transporting units
Authors: Li Hongchao , Geng Yanhou , Tong Shuwen , Tong Hui , Hua Rong , Su Guangping , Wang Lixiang , Jing Xiabin , Wang Fosong
Published: August 2002

A series of light‐emitting poly(p‐phenylene vinylene)s with triphenylamine units as hole‐transporting moieties in the main chain were synthesized via Wittig condensation in good yields. The newly formed vinylene double bonds possessed a trans configuration, which was confirmed by Fourier transform infrared and NMR spectroscopy. The high glass‐transition temperature (83–155 °C) and high decomposition temperature (>300 °C) suggested that the resulting copolymers possessed high thermal stability. These copolymers, especially TAAPV1, possessed a high weight‐average molecular weight (47,144) and a low polydispersity index (1.55). All the copolymers could be dissolved in common organic solvents, such as tetrahydrofuran (THF), CHCl3, CH2Cl2, and toluene, and exhibited intense photoluminescence in THF (the emission maxima were located from 478 to 535 nm) and in film (from 478 to 578 nm). The low onsets of the oxidation potential (0.6–0.75 V) suggested that the alternating copolymers possessed a good hole‐transporting property due to the incorporation of triphenylamine moieties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3278–3286, 2001
Velocity‐correlation analysis in polymer–solvent mixtures
Authors: Vergara Alessandro , Paduano Luigi , Sartorio Roberto
Published: August 2002

The subject of this article is the combined interpretation of intradiffusion and mutual‐diffusion data for polymer–solvent mixtures in terms of integrals over velocity self‐correlation functions and velocity cross‐correlation functions. The combination of mutual‐diffusion, intradiffusion, and activity data allows the evaluation of velocity‐correlation coefficients (VCCs) and distinct‐diffusion coefficients in systems containing one monodisperse solute. This study is the first attempt to extend these approaches to polymers that are polydisperse solutes. Because of the polydispersity, this correlation analysis may become critical for polymers. Its application to polydisperse samples requires the reduction of intradiffusion and mutual‐diffusion coefficients to the same average. After such a reduction, the VCCs and distinct‐diffusion coefficients are evaluated for a homologous series of poly(ethylene glycol)s (PEGs). Attractive PEG–PEG interactions depend on the chain length and concentration of PEG. In this analysis, network formation in PEG–water systems appears to be a smooth process. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 43–51, 2002
Development of a simultaneous measurement system of x‐ray diffraction and raman spectra: Application to structural study of crystalline‐phase transitions of chain molecules
Authors: Tashiro Kohji , Kariyo Sobiroh , Nishimori Akihito , Fujii Takashi , Saragai Seishi , Nakamoto Shinsuke , Kawaguchi Tatsuya , Maatsumoto Akikazu , Rangsiman Orapin
Published: August 2002

The development of a bench‐top‐type system for simultaneous measurement of X‐ray diffraction and Raman spectra has been made to investigate structural changes in the phase transitions of chain molecules such as polyethylene, n‐alkane, and so forth from various viewpoints. For the X‐ray diffraction measurement an imaging plate or a charge‐coupled device camera was used as a two‐dimensional detector. For the Raman spectral measurement a miniature Raman spectrometer was used with optical fibers for the irradiation of incident laser beams and collection of scattered signals. For example, in the heating process of the n‐C30H62 sample, the phase transition from orthorhombic‐to‐hexagonal lattices could be detected clearly by the X‐ray and Raman measurements. By comparing these two different types of data in detail, an intimate relationship between conformational disordering and rotational motion of molecular chains is detected more clearly than before. Also, similar discussion can be made for the orthorhombic‐to‐hexagonal phase transition of the geometrically constrained polyethylene sample occurring immediately below the melting point. Another example concerns the structural change in the photoinduced solid‐state polymerization of cis,cis‐diethylmuconate single crystal. From the shifts in the X‐ray reflection position and Raman frequency characteristic of the produced polymer, it was found that the molecular deformation of the polymer chains and lattice strain was induced in the early stage of the polymerization reaction. For the ferroelectric‐phase transition of vinylidene fluoride copolymer, the simultaneous measurement was made for collecting triple information of small‐angle and wide‐angle X‐ray scatterings and Raman spectra to know the relationship between the structural change in the crystal lattice and the morphological change in the lamellar stacking mode. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 495–506, 2002; DOI 10.1002/polb.10112
Film‐formation property of vinylidene chloride‐methyl methacrylate copolymer latex. I. Effect of emulsion‐polymerization process
Authors: Sakai Hideki , Kodani Takahiko , Takayama Atsuko , Nomura Mamoru
Published: August 2002

Changes in minimum film‐formation temperature (MFFT) during storage of latexes prepared from 91:9 wt % vinylidene chloride (VDC)‐methyl methacrylate (MMA) monomer mixture by seeded batch and seeded semicontinuous emulsion polymerization were investigated, with attention centered on polymer‐crystallization behavior during storage in the dispersed state. MFFT of latex prepared by the seeded batch process rose to 47 °C, whereas that of latex prepared by seeded semicontinuous process remained below 14 °C with storage at 20 °C for 12 weeks. Infrared absorption of latexes in the dispersed state and wide‐angle X‐ray diffraction of powder polymers obtained by lyophilization of fresh and stored latexes both indicated a much greater increase in polymer crystallinity during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Analysis of the copolymer composition drift calculated from reactivity ratios and 1H NMR analysis indicated a wider sequence distribution and longer VDC sequences in polymer prepared by the seeded batch process than in polymer prepared by the seeded semicontinuous process. This explained the higher rate of crystallization during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Rising crystallinity during storage in the dispersed state is believed to have caused the MFFT rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 939–947, 2002
Crystal structure and morphology of biaxially oriented polyamide 12 films
Authors: Rhee Sangkeun , White James L.
Published: August 2002

The structural and morphological characteristics of biaxially oriented polyamide 12 films are described on the basis of the results from differential scanning calorimetry, wide‐angle X‐ray diffraction (WAXD), polarized FT‐IR spectroscopy, and small angle X‐ray scattering (SAXS). The WAXD patterns of the oriented polyamide 12 films indicated only the monoclinic γ crystal with little dimensional changes of its unit cell depending on the stretching conditions. The crystallographic angles (α = γ = 90°, β = 121°) that were determined via the WAXD patterns confirmed the monoclinic symmetry of the γ crystal. Annealing the films stretched at 115 °C in boiling 20% formic acid solution did not result in structural changes of the crystalline unit cell. The chain‐axis repeat distance of 31.9 Å for the γ crystal was experimentally obtained with (0 26 0) planes. It was shortened as compared with that of all‐trans conformation. For films having primary orientation to MD, normals to the basal plane of folded‐chain lamellae were parallel to MD (primary stretch direction) resulting in two‐point SAXS patterns. Growth in long spacing with an increase of stretch temperature was discovered. Annealing the films induced further elongation in long spacing. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1189–1200, 2002
Correlation between digital clubbing and pulmonary function in cystic fibrosis
Authors: Nakamura Craig T. , Ng Gladys Y. , Paton James Y. , Keens Thomas G. , Witmer James C. , Bautista‐Bolduc Daisy , Woo Marlyn S.
Published: August 2002

The correlation between digital clubbing and certain pulmonary function derangements (hypoxemia and FEV1) was previously described. However, the relationship between digital clubbing and other measures of pulmonary function or the presence of liver disease in patients with cystic fibrosis (CF) is poorly defined. Hence we compared the digital clubbing index (CI: ratio of distal phalangeal depth to interphalangeal depth) of 100 patients with CF (43 males, 57 females; mean age, 15.7 ± 7.3 years) with that of 100 age‐ and gender‐matched healthy controls. Digital clubbing was defined as a CI ≥ 1.00 (mean + 2.6 SD; 99% of normal subjects). The CI and its relationship to pulmonary function and to liver disease was then evaluated in the CF patients.

Digital clubbing was present in 75/100 (75%) of CF patients but was absent in all controls (P < 0.0001). In CF patients, CI was inversely correlated with PaO2 (r = −0.555; P < 0.001), FEV1 (r = −0.499; P < 0.001), and FEF25–75% (r = −0.404; P < 0.001), and was positively correlated with RV (r = 0.285; P < 0.05) and the slope of phase 3 of single‐breath nitrogen washout (SP3N2) (r = 0.532; P < 0.01). There was no significant correlation between CI and age (r = 0.020; P = 0.84), TLC (r = −0.097; P = 0.34), PaCO2 (r = 0.167; P = 0.10), or history of liver disease (P = 0.08).

We conclude that in CF, the degree of digital clubbing is related to degree of hypoxemia, airways obstruction, hyperinflation, and nonuniformity of ventilation. Pediatr Pulmonol. 2002; 33:332–338. © 2002 Wiley‐Liss, Inc.
Serial changes in levels of IL‐6 and IL‐1β in premature infants at risk for bronchopulmonary dysplasia*
Authors: Kazzi S. Nadya J. , Romero Roberto , McLaughlin Kathleen , Ager Joel , Janisse James
Published: August 2002

The aim of this study was to define the inflammatory changes occurring in the lungs of infants at risk for bronchopulmonary dysplasia (BPD) over the first 28 days of life, and to define an optimal strategy for steroids therapy in the prevention of BPD. We measured levels of interleukin‐6 (IL‐6) and interleukin‐1 beta (IL‐1β) in tracheal aspirate (TA) samples and blood of premature infants with severe respiratory distress syndrome RDS (n = 45) on the first day of life prior to initiation of surfactant therapy and on days 5–7, 12–14, 19–21, and 26–28. Levels of IL‐6 and IL‐1β were determined with a commercially available enzyme‐linked immunoassay. Logistic regression analyses were performed in order to examine differences in trends in levels of IL‐6 and IL‐1β between groups of infants. Infants were divided into group I (n = 30, FiO2 ≤ 0.35 at 28 days) and group II (n = 15, FiO2 > 0.35 based on their likelihood of developing BPD at 36 weeks postconceptional age (PCA).

The infants were comparable with respect to mean ( ± SEM) birth weight (895 ± 33 g vs. 900 ± 40 g), gestational age (27 ± 0.38 weeks vs. 27 ± 0.54 weeks), and severity of respiratory illness at entry into the study (mean airway pressure: 12 ± 1 cmH2O vs. 12 ± 1 cmH2O, and oxygen index: 15 ± 2 vs. 19 ± 4) (group I vs. group II, respectively). Logistic regression analyses failed to reveal any significant differences in linear trends of levels of IL‐6 and IL‐1β in TA samples between both groups of infants. No particular pattern of change in levels of IL‐6 or IL‐1β could be identified among groups of infants. Levels of IL‐6 and IL‐1β in TA samples on the first day of life failed to predict the need for FiO2 > 0.35 at 28 days of age.

We could not identify an increasing trend or a specific pattern of changes in postnatal levels of IL‐6 or IL‐1β in TA samples of infants who were at greater risk of developing BPD at 36 weeks PCA compared to infants who were not. Pediatr Pulmonol. 2001; 31:220–226. © 2001 Wiley‐Liss, Inc.
Cystic fibrosis‐related deaths in infancy and the effect of newborn screening
Authors: Doull Iolo J.M. , Ryley Henry C. , Weller Peter , Goodchild Mary C.
Published: August 2002

Although newborn screening for cystic fibrosis (CF) is widely advocated, hard evidence in its favor is difficult to obtain, partly because of a dramatically improved life expectancy. Between 1985–l989 infants, born in Wales and the West Midlands were randomized to newborn CF screening by heel‐prick immunoreactive trypsin (IRT) measurement or diagnosis by clinical presentation. Eligible children with CF who died in the first 5 years of life were identified from the local pediatricians and from the National UK CF Survey.

In all, 230,076 infants were randomized to be screened, while 234,510 were unscreened. One hundred seventy‐six CF children were identified, of whom 7 died in the first 5 years of life, 3 having presented with meconium ileus. Median age of diagnosis in the screened group was 8 weeks. On an intention to treat analysis, all 4 nonmeconium ileus‐related deaths occurred in the unscreened group (Fisher's exact test, P < 0.05). However, the clinical presentation of 2 of these infants led to them being diagnosed prior to 8 weeks, i.e., earlier than would have been likely by screening.

In conclusion, newborn screening has the potential to decrease infant CF deaths, but if it is to be successful, identification and treatment must occur as soon as possible after birth. Pediatr Pulmonol. 2001; 31:363–366. © 2001 Wiley‐Liss, Inc.