bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of the structural parameters of a series of fluoromonoacrylates on the surface properties of cured films
Authors: Ameduri B. , Bongiovanni R. , Lombardi V. , Pollicino A. , Priola A. , Recca A. 
Published: August 2002

AbstractA series of fluorinated acrylates [F(CF2)q(CH2)pOCOCHCH2, where q = 8 and p = 2 ÷ 11) were synthesized and used as comonomers in the photopolymerization of acrylic systems. These fluoroacrylates were synthesized in a three‐step procedure through the radical addition of perfluoroalkyliodides to an unsaturated alcohol followed by their acrylation. The mixtures, containing up to 0.8% (w/w) of the comonomers, produced transparent films after UV curing; they showed changes in the surface properties as a function of the comonomer type and concentration. With contact‐angle and X‐ray photoelectron spectroscopy analyses, the relationship between the structure of the monomers and the surface properties of the UV‐cured films was investigated: the wettability decreased, depending on the length of the fluorinated group (q value) and the hydrogenated segment of the monomer (p value). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4227–4235, 2001
Synthesis of star‐shaped poly(D,L‐lactic acid‐alt‐glycolic acid)‐b‐poly(L‐lactic acid) with the poly(D,L‐lactic acid‐alt‐glycolic acid) macroinitiator and stannous octoate catalyst
Authors: Dong Chang‐Ming , Qiu Kun‐Yuan , Gu Zhong‐Wei , Feng Xin‐De 
Published: August 2002

AbstractTwo types of three‐arm and four‐arm, star‐shaped poly(D,L‐lactic acid‐alt‐glycolic acid)‐b‐poly(L‐lactic acid) (D,L‐PLGA50‐b‐PLLA) were successfully synthesized via the sequential ring‐opening polymerization of D,L‐3‐methylglycolide (MG) and L‐lactide (L‐LA) with a multifunctional initiator, such as trimethylolpropane and pentaerythritol, and stannous octoate (SnOct2) as a catalyst. Star‐shaped, hydroxy‐terminated poly(D,L‐lactic acid‐alt‐glycolic acid) (D,L‐PLGA50) obtained from the polymerization of MG was used as a macroinitiator to initiate the block polymerization of L‐LA with the SnOct2 catalyst in bulk at 130 °C. For the polymerization of L‐LA with the three‐arm, star‐shaped D,L‐PLGA50 macroinitiator (number‐average molecular weight = 6800) and the SnOct2 catalyst, the molecular weight of the resulting D,L‐PLGA50‐b‐PLLA polymer linearly increased from 12,600 to 27,400 with the increasing molar ratio (1:1 to 3:1) of L‐LA to MG, and the molecular weight distribution was rather narrow (weight‐average molecular weight/number‐average molecular weight = 1.09–1.15). The 1H NMR spectrum of the D,L‐PLGA50‐b‐PLLA block copolymer showed that the molecular weight and unit composition of the block copolymer were controlled by the molar ratio of L‐LA to the macroinitiator. The 13C NMR spectrum of the block copolymer clearly showed its diblock structures, that is, D,L‐PLGA50 as the first block and poly(L‐lactic acid) as the second block. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 409–415, 2002
Synthesis and properties of fluorinated polyimides. 1. Derived from novel 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl
Authors: Banerjee Susanta , Madhra Mukesh Kumar , Salunke Arun Kashinath , Maier Gerhard 
Published: August 2002

AbstractA new diamine monomer, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl (ATFT) was synthesized that led to a number of novel fluorinated polyimides by solution as well as thermal imidization routes when reacted with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), or 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ATFT/BTDA and ATFT/6FDA derived from both routes were soluble in several organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide. The polyimide ATFT/PMDA was only soluble in N‐methylpyrollidone. The polyimide films had low water absorption of 0.3–0.7%, low dielectric constants of 2.72–3.3 at 1 Hz, refractive indices of 1.594–1.647 at 589.3 nm, and optical transparency >85%. These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 532 °C in air and good isothermal stability; only 7% weight loss occurred at 400 °C after 7 h, and less than 0.6% weight loss was observed at 315 °C for 5 h. Transparent thin films of these polyimides exhibited tensile strengths up to 112 MPa, a modulus of elasticity up to 3.05 GPa, and elongation at break up to 21% depending on the repeating unit structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1016–1027, 2002
Photochemical reactions of quaternary ammonium dithiocarbamates as photobase generators and their use in the photoinitiated thermal crosslinking of poly(glycidyl methacrylate)
Authors: Tachi Hideki , Yamamoto Takayuki , Shirai Masamitsu , Tsunooka Masahiro 
Published: August 2002

AbstractThe photochemical behavior of quaternary ammonium salts (QA salts) with N,N‐dimethyldithiocarbamate as photobase generators and the photoinitiated thermal crosslinking of poly(glycidyl methacrylate) (PGMA) with the QA salts were investigated. The formation of basic compounds in the photolysis of 1‐phenacyl‐(1‐azonia‐4‐azabicyclo[2,2,2]octane) N,N‐dimethyldithiocarbamate was ascertained by the color change of phenol red as an acid–base indicator. 1H NMR spectra of photoproducts in CDCl3 under N2 showed that the photolysis of 1‐naphthoylmethyl‐(1‐azonia‐4‐azabicyclo[2,2,2]octane) N,N‐dimethyldithiocarbamate resulted in the quantitative formation of triethylenediamine and a dithiocarbamate derivative. The presence of oxygen in the photolysis decreased the photolysis rate. The amine was also detected in its photolysis in polystyrene films. The effects of ammonio groups and counteranions of QA salts on the photoinitiated thermal crosslinking of PGMA films were also investigated. Quaternary ammonium dithiocarbamates acted as excellent photobase generators and effective photoinitiated thermal crosslinkers for PGMA. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1329–1341, 2001
New concept of positive photosensitive polyimide: Reaction development patterning (RDP)
Authors: Fukushima Takafumi , Oyama Toshiyuki , Iijima Takao , Tomoi Masao , Itatani Hiroshi 
Published: August 2002

AbstractA soluble multiblock copolyimide without specific functional groups such as OH and COOH was prepared by a direct one‐pot polycondensation of two types of dianhydrides and diamines in the presence of γ‐valerolactone/pyridine catalyst usingN‐methylpyrrolidone (NMP)/toluene mixture as a solvent. The polyimide film containing the photosensitive agent diazonaphthoquinone (DNQ) compound gave positive‐tone behavior by UV irradiation, followed by development in a mixture of ethanolamine/NMP/H2O (1/1/1 by weight). The scanning electron microscopic photograph of the resultant image showed fine patterns with about 20 μm film thickness. Its pattern forming was based on the photorearrangement of diazonaphthoquinone, a process in which the ring‐opening reaction of imide units of the polyimide with the amine used as a developer and the following degradation of the polymer are induced. Such a new imaging technique combines principles of photolithography and etching of a polyimide to give, what we call, reaction development patterning in which the main chemical reactions directly related to the pattern formation occur during development. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3451–3463, 2001
Analysis of the residual entropy of amorphous polyethylene at 0 K*
Authors: Pyda M. , Wunderlich B. 
Published: August 2002

AbstractThe residual entropy of amorphous polyethylene (PE) at 0 K is discussed within the framework of the heat capacity (Cp). The measured Cp of the liquid was extended from the glass transition to low temperature by separately finding its three parts—the vibrational, conformational, and external contributions—and extrapolating each to low temperature. The vibrational Cp was calculated from the frequency distributions of the group vibrations on the basis of force constants obtained from experimental infrared and Raman spectra as well as the skeletal vibrations in the amorphous solid (glass) obtained from fitting of the appropriate experimental Cp to Debye functions in the form suggested by Tarasov. The conformational part of Cp was evaluated from a fit of the heat capacity of the liquid, decreased by the contributions of the vibrational and external parts, to a one‐dimensional Ising model that can be extrapolated to 0 K and requires two discrete states described by stiffness, cooperativity, and a degeneracy parameter. The external part was computed from the experimental data for expansivity and compressibility, fitted to an empirical equation of state, and modified at low temperatures in accordance with the Nernst–Lindemann approximation. The computed Cp of the liquid PE agreed with the experiment from 600 K to the beginning of the glass transition at about 260 K. Extending the heat capacity to 0 K, bypassing the freezing of the large‐amplitude conformational motion in the glass transition, led to a positive residual entropy and enthalpy and avoided the so‐called Kauzmann paradox. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1245–1253, 2002
Physical characterization of poly(ω‐pentadecalactone) synthesized by lipase‐catalyzed ring‐opening polymerization
Authors: Letizia Focarete Maria , Scandola Mariastella , Kumar Ajay , Gross Richard A. 
Published: August 2002

AbstractThe Candida antarctica lipase B (Novozyme‐435)‐catalyzed ring‐opening polymerization of ω‐pentadecalactone in toluene was performed. Poly(ω‐pentadecalactone) [poly(PDL)] was obtained in a 93% isolated yield in 4 h with a number‐average molecular weight of 64.5 × 103 g/mol and a polydispersity index of 2.0. The solid‐state properties of poly(PDL) were investigated by thermogravimetric analysis (TGA) coupled with mass spectrometry, differential scanning calorimetry (DSC), stress–strain measurements, wide‐angle X‐ray diffraction, and dynamic mechanical and dielectric spectroscopies. Poly(PDL) is a crystalline polymer that melts around 100 °C. The polyester shows good thermal stability, with a main TGA weight loss centered at 425 °C. Because of the high degree of poly(PDL) crystallinity, the glass transition (−27 °C) is revealed by relaxation techniques such as dynamic mechanical and dielectric spectroscopies, rather than by DSC. In addition to the glass transition, the viscoelastic spectrum of poly(PDL) also shows two low‐temperature secondary relaxations centered at −130 (γ) and −90 °C (β). They are attributed to local motions of the long methylene sequence (γ) and complex units involving water associated with the ester groups (β). The mechanical properties of poly(PDL) are typical of a hard, tough material, with an elastic modulus and yield parameters comparable to those of low‐density polyethylene. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1721–1729, 2001
Nonlinear rheology of highly entangled polymer solutions in start‐up and steady shear flow
Authors: Islam Mohammad T. , Archer Lynden A. 
Published: August 2002

AbstractOrientation angle and stress‐relaxation dynamics of entangled polystyrene (PS)/diethyl phthalate solutions were investigated in steady and step shear flows. Concentrated (19 vol %) solutions of 0.995, 1.81, and 3.84 million molecular weight (MW) PS and a semidilute (6.4 vol %) solution of 20.6 million MW PS were used to study the effects of entanglement loss on dynamics. A phase‐modulated flow birefringence apparatus was developed to facilitate measurements of time‐dependent changes in optical equivalents of shear stress(n12≈ Cσ)and first normal stress differences(n1= n11− n22≈ CN1)in a planar‐Couette shear‐flow geometry. Flow birefringence results were supplemented with cone‐and‐plate mechanical rheometry measurements to extend the range of shear rates over which entangled polymer dynamics are studied. In slow(τ>) steady shear‐flow experiments using the ultrahigh MW polymer sample (20.6 × 106MW PS), steady‐staten12andn1results manifest unusual power‐law dependencies on shear rate[n12,ss∼0.4andn1,ss∼0.8]. At shear rates in the rangeτ<< τ, steady‐state orientation anglesχSSare found to be nearly independent of shear rate for all but the most weakly entangled materials investigated. For solutions containing the highest MW PS, an approximate plateau orientation angleχpin the range 20–24° is observed;χpvalues ranging from 14 to 16° are found for the other materials. In the start‐up of fast steady shear flow(γ˙ ≥ τ), transient undershoots in orientation angle are also reported. The molecular origins of these observations were examined with the help of a tube model theory that accommodates changes in polymer entanglement density during flow. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2275–2289, 2001
Permafrost monitoring in the high mountains of Europe: the PACE Project in its global context
Authors: Harris Charles , Haeberli Wilfried , Vonder Mühll Daniel , King Lorenz 
Published: August 2002

AbstractThis paper introduces the structure and organization of permafrost monitoring within global climate‐related monitoring programmes. The five‐tiered principle proposed for the Global Hierarchical Observing Strategy (GHOST) is applied to the Global Terrestrial Network for Permafrost (GTN‐P) monitoring system, and the European network of mountain permafrost boreholes established by the PACE project is discussed in the context of GTN‐P. Borehole design and standard PACE instrumentation are described and some preliminary data from selected boreholes are presented. The broader research aims of the PACE programme include geophysical investigations, mapping and GIS strategies, numerical distribution modelling, physical modelling of thaw‐related slope processes and mountain permafrost hazard assessment. Copyright © 2001 John Wiley & Sons, Ltd.RÉSUMÉLe présent article décrit la structure et l'organisation du programme de surveillance du pergélisol et son intégration dans les programmes de surveillance du climat. Le principe à 5 niveaux proposé pour la stratégie d'observation hiérarchique (GHOST) est appliquée au réseau global de surveillance terrestre du pergélisol (GTN‐P). Le réseau européen de sondages dans le pergélisol établi par le projet PACE est discuté dans le contexte du GTN‐P. La localisation des sondages et l'instrumentation standard de PACE sont décrites et quelques données préliminaires de certains sondages sélectionnés sont présentées. Les recherches du programme PACE comprennent des recherches géophysiques, des stratégies de cartographie et de systèmes d'information géographique, des modèles de distribution numérique, des modèles physiques des processus de versants en relation avec le dégel et enfin des estimations des risques liés au pergélisol de montagne. Copyright © 2001 John Wiley & Sons, Ltd.
Terrain parameters and remote sensing data in the analysis of permafrost distribution and periglacial processes: principles and examples from southern Norway
Authors: Etzelmüller Bernd , Ødegård Rune S. , Berthling Ivar , Sollid Johan Ludvig 
Published: August 2002

AbstractAlpine permafrost and frost‐related geomorphological processes are sensitive to climatic change. Thus, there is an increasing demand for permafrost maps in high‐alpine environments. The objective of this paper is to present the application of terrain analysis and classification based on digital elevation models (DEMs) together with remotely sensed data (e.g. Landsat TM) in mapping of permafrost and slope activity as a supplement to existing methods. The study reviews principles and recent developments in this field, and presents three different approaches in the form of case studies from mountain areas of southern Norway. Copyright © 2001 John Wiley & Sons, Ltd.RÉSUMÉLe pergélisol alpin et les processus géomorphologiques dus au gel sont sensibles aux changements de climat. II y a, en conséquence, une demande accrue de cartes du pergélisol dans les environnements de hautes altitudes. L'objectif de cet article est de présenter comment l'analyse du terrain et une classification du sol basée sur des modèles d'altitude, combinées avec l'utilisation de données de télédétection (Landsat TM), peuvent servir à cartographier le pergélisol et l'activité géomorphologique sur les versants, et constituer un supplément aux méthodes déjà existantes. L'étude passe en revue les principes et les développements récents dans ce domaine et présente trois différentes approches dans des études de cas de régions montagneuses de Norvège méridionale. Copyright © 2001 John Wiley & Sons, Ltd.
Subcutaneous terbutaline in children with chronic severe asthma*
Authors: Payne Donald N.R. , Balfour‐Lynn Ian M. , Biggart Elizabeth A. , Bush Andrew , Rosenthal Mark 
Published: August 2002

AbstractA continuous subcutaneous infusion of terbutaline (CSIT) was used to treat 8 children with chronic severe asthma who continued to experience frequent symptoms, despite treatment with regular oral prednisolone. Five patients experienced a symptomatic improvement from CSIT, leading to a reduction in regular medication. Three patients did not experience any lasting benefit from CSIT. The most common side effects were related to the infusion site (bruising and local infection).CSIT may lead to an improvement in symptoms and a reduction in oral steroid dose in selected children with chronic severe asthma. These initial findings support the need for further controlled studies to evaluate the use of CSIT in severe childhood asthma. Pediatr Pulmonol. 2002; 33:356–361. © 2002 Wiley‐Liss, Inc.
Mechanical ventilation in children with severe asthma
Authors: Malmström Kristiina , Kaila Minna , Korhonen Kaj , Dunder Teija , Nermes Merja , Klaukka Timo , Sarna Seppo , Juntunen‐Backman Kaisu 
Published: August 2002

AbstractHospital admissions for childhood asthma have increased during the past few decades. The aim of this study was to describe the need for mechanical ventilation for severe asthma exacerbation in children in Finland from 1976 to 1995. We reviewed medical records and collected data retrospectively from all 5 university hospitals in Finland, thus covering the entire population of about 5 million. The endpoints selected were the number of admissions and readmissions leading to mechanical ventilation, duration of stay in the hospital, and mortality. Moreover, asthma medications prescribed prior to admission and administered in the intensive care unit (ICU), as well as the etiology of the exacerbation associated with mechanical ventilation were examined.Mechanical ventilation was required in 66 ICU admissions (59 patients). This constituted approximately 10% of all 632 admissions for acute asthma to an ICU. The number of admissions decreased from 1976 to 1995: 41 admissions between 1976 and 1985 vs. 25 admissions during the next 10‐year period. The mean age at admission to the ICU was 3.6 years, and 46% of the patients were boys. Prior to the index admission, 70% of the patients had used asthma medication such as oral bronchodilator (50%), inhaled bronchodilator (20%), theophylline (38%), inhaled glucocorticoid (18%), oral glucocorticoid (5%), and cromoglycate (7%). Respiratory infection was by far the most common cause of all the exacerbations (61%), followed by food allergy (8%) and gastroesophageal reflux (3%). In 28% of cases the cause of the severe asthma exacerbation could not be identified. In the mechanically ventilated patients readmissions occurred 38 times between 1976 and 1985 vs. 5 times between 1986 and 1995. Five of the patients who received mechanical ventilation died, and in 3 of these patients asthma was the event causing death.In conclusion, there has been decrease in the number of first and repeat ICU admission for asthma requiring mechanical ventilation between 1970 and 1995. This trend occurred despite a simultaneous 5% yearly increase in hospital admissions for childhood asthma during these 2 decades. Pediatr Pulmonol. 2001; 31:405–411. © 2001 Wiley‐Liss, Inc.
Prostate volume and prostate‐specific antigen in the absence of prostate cancer: A review of the relationship and prediction of long‐term outcomes
Authors: Lieber Michael M. , Jacobsen Steven J. , Roberts Rosebud O. , Rhodes Thomas , Girman Cynthia J. 
Published: August 2002

AbstractBackgroundThe risk for long‐term outcomes associated with benign prostatic hyperplasia (BPH) has not been well characterized. Untreated, BPH can lead to complications and negative outcomes, such as deterioration of bladder function, urinary tract infection, acute urinary retention (AUR), and surgery.MethodsA literature review was conducted to summarize the results of studies investigating the relationship of prostate volume and PSA with prediction of long‐term outcomes in the absence of prostate cancer.ResultsIn the studies reviewed, men with moderate to severe symptoms, depressed uroflow, prostatic enlargement and elevated PSA were at greater risk for developing subsequent AUR or surgery. Men with prostatic enlargement had a 3‐fold higher risk for acute urinary retention and were 4 times more likely to have had any treatment for BPH.ConclusionsThe results of these studies may assist physicians in discussing treatment options as well as long‐term complications with patients. Prostate 49:208–212, 2001. © 2001 Wiley‐Liss, Inc.
Dissecting protein–protein recognition sites
Authors: Chakrabarti Pinak , Janin Joël 
Published: August 2002

AbstractThe recognition sites in 70 pairwise protein–protein complexes of known three‐dimensional structure are dissected in a set of surface patches by clustering atoms at the interface. When the interface buries <2000 Å2of protein surface, the recognition sites usually form a single patch on the surface of each component protein. In contrast, larger interfaces are generally multipatch, with at least one pair of patches that are equivalent in size to a single‐patch interface. Each recognition site, or patch within a site, contains a core made of buried interface atoms, surrounded by a rim of atoms that remain accessible to solvent in the complex. A simple geometric model reproduces the number and distribution of atoms within a patch. The rim is similar in composition to the rest of the protein surface, but the core has a distinctive amino acid composition, which may help in identifying potential protein recognition sites on single proteins of known structures. Proteins 2002;47:334–343. © 2002 Wiley‐Liss, Inc.
Distributions of beta sheets in proteins with application to structure prediction
Authors: Ruczinski Ingo , Kooperberg Charles , Bonneau Richard , Baker David 
Published: August 2002

AbstractWe recently developed the Rosetta algorithm for ab initio protein structure prediction, which generates protein structures from fragment libraries using simulated annealing. The scoring function in this algorithm favors the assembly of strands into sheets. However, it does not discriminate between different sheet motifs. After generating many structures using Rosetta, we found that the folding algorithm predominantly generates very local structures. We surveyed the distribution of β‐sheet motifs with two edge strands (open sheets) in a large set of non‐homologous proteins. We investigated how much of that distribution can be accounted for by rules previously published in the literature, and developed a filter and a scoring method that enables us to improve protein structure prediction for β‐sheet proteins. Proteins 2002;48:85–97. © 2002 Wiley‐Liss, Inc.