bluuebunny/crossref_metadata_2025_split huggingface dataset:
Allotype imbalance or microsatellite mutation in low‐grade soft tissue sarcomas of the extremities in adults
Authors: Hoon Cho Nam , Cordon‐Cardo Carlos , Li G. C. , Hyun Kim See 
Published: October 2002

AbstractThe ability to repair DNA double‐strand breaks is essential to maintain chromosomal stability. Virtually all soft tissue sarcomas contain chromosomal instabilities, including clonal aberrations and cytogenetic aberrations. However, the relevance of DNA‐dependent protein kinase (DNA‐PK) in the pathogenesis of soft tissue sarcoma has not been clarified. The main aim of this work is to compare the prognostic impact of genotypic imbalance in low‐grade soft tissue sarcomas of the extremities, and to correlate this with the translational level of DNA‐PK. This study investigated 28 adult low‐grade malignant spindle cell tumours of the extremities, predominantly fibrosarcomas, for loss of heterozygosity (LOH) and microsatellite mutation on flanking regions of each DNA‐PK subunit, with identical immunophenotypes. Twelve different polymorphic markers flanking the specific loci of three subunits comprise the genetic map of DNA‐PK, at 22q13, 2q35, and 8q11. Translational activity was also analysed by western blot and conventional immunohistochemistry. The overall sarcoma 5‐year survival rate was 61.7%. LOH was identified in the specific coding region of DNA‐PK in 39.29% for the DNA‐PK catalytic subunit (cs), 17.86% for Ku70, and only 7.14% for Ku80. A positive LOH for DNA‐PKcs was shown to be a significant factor for poor survival (log rank test p = 0.0160). Immunoreactivity and immunoblot results correlated with the loss of DNA‐PKcs allotype in soft tissue sarcoma (Fisher's exact test p = 0.0037). Ku70 and DNA‐PKcs were almost identical in terms of immunoreactivity. In conclusion, whereas microsatellite mutation seems an uncommon event during the evolution of low‐grade fibrosarcoma of the extremities in adults, the loss of DNA‐PKcs defines a biologically more aggressive subset. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of the basicity of substituted dimethylamines in different solvents by theoretical descriptors
Authors: Headley Allan D. , Nam Jaewook 
Published: October 2002

AbstractBy using theoretically determined descriptors in quantitative structure–property relationships, quick and good a priori predictions of molecular properties can be accomplished. In this study, theoretical linear solvation energy relationship descriptors are used to analyze structural effects that contribute to the basicity variation of substituted dimethylamines in different solvents. A multilinear regression (MLR) analysis approach is used to generate equations and, owing to the goodness of the ‘fit’ of the different MLR equations, the descriptors used account very well for the structural effects that determine the relative basicity of dimethylamines. Good agreement is obtained between the basicity values predicted by this method and the experimental basicity values of 14 substituted dimethylamines in eight solvents and the gas phase. The Lewis basicity ϵB and the polarizability/dipolarity πi are the important factors that contribute to basicity variation. For the basicity of NCCH2N(CH3)2, a good prediction was not achieved and a discussion is presented. Copyright © 2001 John Wiley & Sons, Ltd.
Reactive intermediates via Fourier transform mass spectrometry
Authors: Kass Steven R. , Broadus Katherine M. 
Published: October 2002

AbstractA new method for the selective preparation of radical anions in the gas phase is described. Dicarboxylate anions are generated in a Fourier transform mass spectrometer via electrospray ionization, and both carboxylates and an electron are removed to afford odd‐electron anions via sequential fragmentations. Energetic measurements on these species enable the heats of formation of neutral compounds to be determined. The heats of hydrogenation of benzocyclobutadiene and acenaphthyne are used to illustrate this methodology and the antiaromaticity and/or strain energy of these molecules are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Historical perspectives on living anionic polymerization
Authors: Smid Johannes 
Published: October 2002

AbstractA brief overview of the role that Dr. Michael Szwarc has played in unraveling the mechanism of living anionic polymerization is presented. Emphasis is placed on the different ionic species that control the propagation reaction in ether‐type solvents. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2101–2107, 2002
Synthesis of block copolymers by the transformation of cationic polymerization into reversible atom transfer radical polymerization
Authors: Cianga Ioan , Hepuzer Yesim , Serhatli Ersin , Yagci Yusuf 
Published: October 2002

AbstractAzo‐containing polytetrahydrofuran (PTHF) obtained by cationic polymerization was used as a macroinitiator in the reverse atom transfer radical polymerization (RATRP) of styrene and methyl acrylate in conjunction with CuCl2/2,2′‐bipyridine as a catalyst. Diblock PTHF–polystyrene and PTHF–poly(methyl acrylate) were obtained after a two‐step process. In the first step of the reaction, stable chlorine‐end‐capped PTHF was formed with the thermolysis of azo‐linked PTHF at 65–70 °C in the presence of the catalyst. Heating the system at temperatures of 100–110 °C started the polymerization of the second monomer, which resulted in the formation of block copolymers. The decomposition behavior of the azo‐linked PTHF and the structure of the block copolymers were determined by 1H NMR and gel permeation chromatography (GPC). Kinetic studies and GPC analyses further confirmed the controlled/living nature of the RATRP initiated by the polymeric radicals. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2199–2208, 2002
Synthesis of comb‐branched polyacrylamide with cationic poly[(2‐dimethylamino)ethyl methacrylate dimethylsulfate] quat
Authors: Zeng Faquan , Shen Youqing , Zhu Shiping 
Published: October 2002

AbstractComb‐branched polyelectrolytes with polyacrylamide backbones and poly[(2‐dimethylamino)ethyl methacrylate methylsulfate] (polyDMAEMA‐DMS) side chains were prepared by free‐radical macromonomer polymerization. PolyDMAEMA‐DMS macromonomers bearing terminal styrenic moieties were synthesized by living anionic polymerization with lithium 4‐vinylbenzylamide (LiVBA) and lithium N‐isopropyl‐4‐vinylbenzylamide (LiPVBA) as initiators. In the presence of LiCl, LiPVBA initiated a living polymerization of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and produced polymers with well‐controlled molecular weights and low polydispersities. LiVBA could not directly initiate DMAEMA polymerization. After being capped with two units of dimethylacrylamide, DMAEMA polymerized with an initiator efficiency of 63%. The quaternization of the poly[(2‐dimethylamino)ethyl methacrylate] macromonomer with dimethyl sulfate yielded the cationic polyDMAEMA‐DMS macromonomer. The polyDMAEMA‐DMS macromonomer had a much higher reactivity than acrylamide in free‐radical polymerization. This might have been due to the formation of polyDMAEMA‐DMS micelles in the polymerization system. The high macromonomer reactivity caused composition drift in a batch process. A semibatch method with a constant polyDMAEMA‐DMS feed rate was used to control the copolymer composition. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2394–2405, 2002
Synthesis and characterization of polystyrene‐b‐poly (1,2‐isoprene‐ran‐3,4‐isoprene) block copolymers with azobenzene side groups
Authors: Hayakawa Teruaki , Horiuchi Shin , Shimizu Hiroshi , Kawazoe Tadashi , Ohtsu Motoichi 
Published: October 2002

AbstractPolystyrene‐b‐poly(1,2‐isoprene‐ran‐3,4‐isoprene) block copolymers with azobenzene side groups were synthesized by the esterification of azobenzene acid chloride with polystyrene‐b‐hydroxylated poly(1,2‐isoprene‐ran‐3,4‐isopenre) block copolymers for creating new photochromic materials. The resulting block copolymers with azobenzene side groups were characterized for structural, thermal, and morphological properties. IR and NMR spectroscopies confirmed that the polymers obtained had the expected structures. Differential scanning calorimetric measurements by heating runs clearly showed the glass transitions of polystyrene and polyisoprene main chains and two distinct first‐order transitions at temperatures of azobenzene side groups around 48 and 83 °C. The microstructure of these block copolymer films was investigated using both transmission electron microscopy (TEM) and near‐field optical microscopy (NOM). TEM images revealed typical microphase‐separated morphologies such as sphere, cylinder, and lamellar structures. The domain spacing of microphase‐separated cylindrical morphology in the NOM image agreed with that of the TEM results. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2406–2414, 2002
Synthesis of new fluorinated allyl ethers for the surface modification of thiol–ene ultraviolet‐curable formulations
Authors: Sangermano M. , Bongiovanni R. , Malucelli G. , Priola A. , Harden A. , Rehnberg N. 
Published: October 2002

AbstractThiol–ene photocurable systems based on a trifunctional thiol [trimethylolpropane tris‐(3‐mercaptopropanoate)] and two different multifunctional allyl ethers (trimethylolpropane triallyl ether and Boltorn U2, an allyl functional dendritic polyester) were examined. To these systems, small amounts (<1 wt %) of fluorinated allyl ethers were added for the modification of their surface properties. Two new fluorinated allyl ethers, 1H,1H‐perfluoro‐1‐heptylallyl ether and 1H,1H‐perfluoro‐1‐decylallyl ether, were synthesized for this purpose by allylation of the corresponding 1H,1H‐perfluoro alcohols. The fluorinated monomers, despite their very low concentrations, caused sharp changes in the surface properties of the films and in the solvent resistance without any changes in the curing conditions and bulk properties. Completely hydrophobic surfaces were obtained (as a result of the selective enrichment of the fluorinated monomers on the film surfaces) that depended on the monomer structure and its concentration. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2583–2590, 2002
Synthesis and characterization of halogen‐containing poly(ether ketone ketone)s
Authors: García Carolina , Lozano Ángel E. , de la Campa José G. , de Abajo J. 
Published: October 2002

AbstractA series of novel poly(ether ketone ketone)s (PEKKs) were synthesized from diphenyl ether and isophthaloyl chloride derivatives such as 5‐halo‐ and 5‐tert‐butyl‐isophthaloyl chloride. The aromatic electrophilic substitution route to polyketones was a convenient route for the preparation of the polymers in high yields via precipitation polycondensation at a low temperature with aluminum trichloride as a catalyst. High molecular weight PEKKs were achieved with number‐average molecular weights of 15,000–100,000 g/mol for polymers that showed good solubility in organic solvents. The presence of substituents greatly modified the spectroscopic features in comparison with those of unsubstituted isophthaloyl poly(ether ketone ketone)s, particularly for the series containing halogens, for which significant variations of the chemical shifts in both 1H and 13C NMR spectra were observed; these shifts could be related to the nature of the halogen. Thermal properties were also affected by the presence of pendent substituents, with clear enhancements of the glass‐transition temperatures, which could be ascribed to the nature and bulkiness of the substituents. Thermogravimetric analyses showed that the new polymers had good thermal resistance, although an important drop in thermal resistance was observed for polymers bearing large halogen atoms, such as bromine and iodine. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2601–2608, 2002
Synthesis and characterization of luminescent polyethers with 2,5‐distyrylthiophene and aromatic oxadiazole chromophores
Authors: Chen Yun , Huang Yu‐Yi , Wu Tzi‐Yi 
Published: October 2002

AbstractTwo new luminescent copolyethers (P1 and P2) with isolated 2,5‐distyrylthiophene‐emitting segments and electron‐transporting 2,5‐diphenyl‐1,3,4‐oxadiazole chromophores were successfully synthesized by the Horner–Wadworth–Emmons reaction. The solubility, optical, and electrochemical properties of the polymers were investigated and correlated with nonlinear thiophene and 1,3,4‐oxadiazole groups. P2 with pendant 1,3,4‐oxadiazole was soluble in common organic solvents such as chloroform, tetrahydrofuran, and C2H2Cl4. Thermogravimetric analysis and differential scanning calorimetry showed that the copolyethers were thermally stable below 345 °C, with glass‐transition temperatures higher than 110 °C. They were yellow‐greenish emitting materials with a band gap of 2.57–2.58 eV estimated from the onset absorption. Incorporating the thiophene moiety narrowed the band gaps of the copolyethers. The photophysical and electronic properties of the polymer and the preliminary electroluminescent device made from the polymer demonstrate that the polymer may be a potential candidate material for the fabrication of polymeric light‐emitting devices. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2927–2936, 2002
Application of ketenes to well‐defined polyester synthesis (4): End‐capping reactions in living anionic polymerization of ethylphenylketene
Authors: Sudo Atsushi , Endo Takeshi 
Published: October 2002

AbstractEnd‐capping reactions of a living polyester, obtained by anionic polymerization of ethylphenylketene (EPK), were carried out. As end‐capping reagents, electrophiles such as alkyl halide and acyl halide were successfully used. Reactivity of the terminal enolate and the resulting terminal structures were elucidated by model reactions, using lithium enolates having low molecular weights, obtained by an equimolar reaction of EPK with butyllithium. Polymerization of EPK by lithium alkoxide and the subsequent end‐capping reaction afforded the corresponding polyester having functional groups at both chain ends and a narrow molecular weight distribution. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3103–3111, 2002
Novel spherical Ziegler–Natta catalyst for polymerization and copolymerization. I. Spherical MgCl2 support
Authors: Ye Zhao‐Yang , Wang Li , Feng Lian‐Fang , Gu Xue‐Ping , Chen Hai‐Hua , Zhang Pu‐Yu , Pan Jie , Jiang Shan , Feng Lin‐Xian 
Published: October 2002

AbstractSpherical MgCl2 adducts used as supports for a Ziegler–Natta catalyst for olefin polymerization were prepared by the general precipitation method. The influence of MgCl2/EtOH (mol/mol) and the dispersion speeds on the particle size (PS) and particle size distribution (PSD) were investigated. It was found that the former played a trivial role in controlling the PS and PSD, and the latter was the key factor. In particular, the influence of ethanol on the crystal structure was further examined, with consideration given to the performance of the supported Ziegler–Natta catalyst. It was believed that the reactions between MgCl2 and ethanol had a controlling effect on the destruction of the original anhydrous MgCl2, which was the key point in the preparation of suitable supports for the latest generation Ziegler–Natta catalyst. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3112–3119, 2002
Morphology and orientation during the deformation of segmented elastomers studied with small‐angle X‐ray scattering and atomic force microscopy
Authors: Sauer Bryan B. , McLean R. Scott , Brill Donald J. , Londono David J. 
Published: October 2002

AbstractSmall‐angle X‐ray scattering (SAXS), atomic force microscopy (AFM), and other techniques were combined in a study of segmented thermoplastic elastomers (Pebax) containing poly(tetramethylene oxide) soft segments and hard blocks of nylon‐12. AFM was used to provide real‐space resolution of the morphology during tensile elongation and after subsequent relaxation. Nanofibril formation, starting at strains of about 1.5×, was characterized in detail, showing the evolution of the number, orientation, and size of these highly stressed load‐bearing fibrils that dominated the mechanical properties. AFM results were combined with two‐dimensional SAXS data to develop a model considering the breakup of the original ribbonlike nylon‐12 lamellae in combination with progressive reformation and orientation of highly stressed fibrils. The complex changes in the two‐dimensional SAXS images included a distorted arc pattern due to increased spacing of the lamellae in the stretch direction at low strains, with an evolution to completely different patterns dominated mainly by intrafibrillar and interfibrillar scattering contributions. Between stretch ratios of 1.5 and 2.3× original lamellae were progressively broken up, and by 3.2×, all lamellae independent of the initial orientation were broken into smaller crystals with low aspect ratios. The results were combined with differential scanning calorimetry and birefringence data taken on films under strain to obtain insight into the microscopic basis for strain softening and plastic deformation in Pebax and related segmented polymers. Birefringence cycling with strain provided a consistent picture with the other techniques for understanding the redistribution of stress on a nanoscopic scale during deformation and relaxation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1727–1740, 2002
Structural and rheological properties of hydrophobically modified alkali‐soluble emulsion solutions
Authors: Knaebel A. , Skouri R. , Munch J. P. , Candau S. J. 
Published: October 2002

AbstractScattering and rheological experiments were carried out on hydrophobically modified alkali‐soluble emulsion solutions at pH ∼ 7.3 as a function of the polymer concentration. The light scattering experiments revealed the existence of a liquidlike order for concentrations below approximately 0.1 × 10−2g cm−3corresponding approximately to the close packing of microgels particles. Above this concentration, the zero‐shear viscosity rose sharply, whereas the ordering disappeared progressively. The results are discussed within the framework of gelation models of associating polymers. Diffusing wave spectroscopy experiments provided estimates of the high‐frequency modulus. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1985–1994, 2002
Influence of gel composition on the solubility parameter of poly(2‐hydroxyethyl methacrylate‐itaconic acid) hydrogels
Authors: Çaykara Tuncer , Özyürek Cengiz , Kantoğlu Ömer , Güven Olgun 
Published: October 2002

AbstractThe solubility parameters of pure poly(2‐hydroxyethyl methacrylate) (PHEMA) and poly(2‐hydroxyethyl methacrylate/itaconic acid) [P(HEMA/IA)] hydrogels were determined by 20 solvents with various solubility parameters in swelling experiments. The solubility parameter of pure PHEMA was 26.93 ± 0.46 (MPa)1/2. The effect of mole percentages of itaconic acid (IA) in P(HEMA/IA) hydrogels on the solubility parameter was investigated. The measured values were compared to literature and solubility values theoretically determined by group contribution values of van Krevelen and Hoy. The incorporation of IA into the hydrogel system slightly increased the solubility parameter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1995–2003, 2002
Effect of chemical activity jumps on the viscoelastic behavior of an epoxy resin: Physical aging response in carbon dioxide pressure jumps
Authors: Alcoutlabi Mataz , Briatico‐Vangosa Francesco , McKenna Gregory B. 
Published: October 2002

AbstractWe report the results from tensile creep tests performed on an epoxy resin in the presence of carbon dioxide at different pressures (Pco2) and at a constant temperature below the glass‐transition temperature. Time‐Pco2 superposition was applied to the data to account for the plasticization effect because of the interaction between the carbon dioxide molecules and the polymer. In addition, physical aging of the epoxy films was investigated with sequential creep tests after carbon dioxide pressure down‐jumps at constant temperature and after temperature down‐jumps at constant carbon dioxide pressure. The isothermal pressure down‐jump experiments showed physical aging responses similar to the isobaric temperature down‐jump experiments. However, the aging rate for the CO2 jump was slightly lower than that for the temperature‐jump (T‐jump) experiments, and the retardation time for the Pco2‐jump experiments was up to 6.3 times longer than for the T‐jump conditions. The results are discussed in terms of classical physical aging and structural recovery frameworks, and speculation about the differences in the energy landscape resulting from the Pco2‐jump and T‐jump experiments is also made. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2050–2064, 2002
Ultimate tensile behavior of linear polyethylene solids
Authors: Nitta Koh‐Hei , Ishiburo Takashi 
Published: October 2002

AbstractThe influence of the elongation rate and temperature on the ultimate tensile properties of melt‐crystallized linear polyethylene solids was investigated, with a double‐edge‐notched specimen to avoid necking, in which uniform deformation could be assumed throughout the experiment. The data on ultimate properties such as the tensile strength and elongation at break for different temperatures could be superimposed, by shifts along the elongation rate axis, to give a master curve as a function of the time to rupture. The shift factors obtained from the superpositioning of both the tensile strength and ultimate strain took the form of the Williams–Landel–Ferry equation. As a result, the ultimate data provided a failure envelope curve that made it possible to predict rupture times when the tensile tests were conducted under any experimental conditions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2018–2026, 2002
Hypoglycemia due to adrenal suppression secondary to high‐dose nebulized corticosteroid
Authors: Dunlop K.A. , Carson D.J. , Shields M.D. 
Published: October 2002

AbstractHigh‐dose inhaled corticosteroids, greater than 400 mcg per day of beclomethasone dipropionate or equivalent, can cause adrenal insufficiency, but a hypoglycemic crisis has not been reported with the use of nebulized corticosteroids. We describe a 21‐month‐old asthmatic boy who had a hypoglycemic seizure during a proven acute adrenal crisis secondary to high‐dose nebulized budesonide treatment. Pediatr Pulmonol. 2002; 34:85–86. © 2002 Wiley‐Liss, Inc.