bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reproductive and anthropometric factors in relation to the risk of lobular and ductal breast carcinoma among women 65–79 years of age
Authors: Li Christopher I. , Malone Kathleen E. , Porter Peggy L. , Weiss Noel S. , Tang Mei‐Tzu C. , Daling Janet R. 
Published: September 2003

AbstractUse of combined estrogen‐progestin hormone replacement therapy appears to be associated with an increased risk of invasive lobular breast carcinomas (ILC) and, to a lesser degree, with risk of invasive ductal carcinoma (IDC). Conceivably, ILCs are more hormonally responsive and so may be more strongly associated than IDCs with reproductive and anthropometric characteristics that can influence hormone levels. However, few epidemiologic studies of breast cancer have evaluated these factors by histologic type. We conducted a population‐based case‐control study of women aged 65–79 years in western Washington State. Responses from 975 women diagnosed with breast cancer during 1997–1999 were compared to those of 1,007 controls. Associations between various reproductive and anthropometric factors and risks of IDC (n = 656) and ILC (n = 196) were evaluated using polytomous logistic regression. Earlier age at menarche, later age at menopause and obesity were more strongly associated with elevated risks of IDC than ILC. Alternatively, oral contraceptive use was associated with an increased risk of ILC but not IDC. Thus, the pattern of results that we observed suggest that factors influencing endogenous hormones and duration of ovarian function may be more strongly associated with IDC risk, while exogenous hormones may be more strongly associated with ILC risk. © 2003 Wiley‐Liss, Inc.
Increase of AKT/PKB expression correlates with gleason pattern in human prostate cancer
Authors: Liao Yongde , Grobholz Rainer , Abel Ulrich , Trojan Lutz , Michel Maurice Stephan , Angel Peter , Mayer Doris 
Published: September 2003

AbstractAKT/PKB is a central signaling molecule related to stimulation of cell proliferation and inhibition of apoptosis. Perturbations of AKT expression and function play an important role in tumor development and progression. We wanted to determine (a) whether AKT is overexpressed in human prostatic tumors, (b) whether AKT expression is correlated with tumor grade, and (c) whether AKT expression correlates with clinicopathological parameters. AKT expression was investigated by immunohistochemistry in sections from 56 paraffin‐embedded prostate specimens displaying benign prostatic tissue (BPT), prostatic intraepithelial neoplasia (PIN), and primary tumors graded 2–5 according to Gleason. The staining intensity for AKT was significantly more pronounced in tumors compared to BPT, with PIN ranging between BPT and carcinomas. Similarly, the fraction of AKT‐positive cells was higher in tumors than in BPT. A score of AKT expression (calculated as product from intensity and fraction of positive cells) ranging from 0–6 was also significantly higher in tumors than in BPT. Furthermore, the intensity of AKT expression in tumors showed a positive correlation with high preoperative serum levels of prostate specific antigen (PSA ≥ 10 ng/ml, p = 0.0325). These data show that AKT is upregulated in prostate cancer and that expression is correlated with tumor progression. © 2003 Wiley‐Liss, Inc.
Modular approach for novel nanostructered polycondensates enabled by the unique selectivity of carbonyl biscaprolactam
Authors: Loontjens Ton 
Published: September 2003

AbstractNew enabling chemistries have been developed to produce novel well‐defined polymeric materials through the additions of small amounts of reactive functional compounds to standard polymers during regular processing steps. We found that carbonyl biscaprolactam and its derivatives couple polymer chains in a strictly linear fashion. The requirements for fast and well‐controlled coupling reactions, a prerequisite to apply this modular concept, were met. The breakthrough to produce a wide variety of novel polymers came when we found that many building blocks, provided with functional groups and blocked isocyanate groups, could be made on the basis of this chemistry. Blocked isocyanate groups are very suitable coupling units to fix desired functions onto polymer backbones. In one example, antifouling coatings were prepared by introducing fluorine groups. In another case, blocked isocyanate functional acrylates were built into a polyacrylate to make self‐crosslinkable coatings. In another illustration, the concept was demonstrated by a novel route to prepare polyrotaxanes from rotaxane monomers provided with blocked isocyanates as polymerizable stopper groups. These reactive functional compounds gave, in a controlled manner, polymeric materials with substantially improved properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3198–3205, 2003
Photoinitiated cationic polymerization of monofunctional benzoxazine
Authors: Kasapoglu Fatmanur , Cianga Ioan , Yagci Yusuf , Takeichi Tsutomu 
Published: September 2003

AbstractThe photoinitiated ring‐opening cationic polymerization of a monofunctional benzoxazine, 3‐phenyl‐3,4‐dihydro‐2H‐1,3‐benzoxazine, with onium salts such as diphenyliodonium hexafluorophosphate and triphenylsulfonium hexafluorophosphate as initiators was examined. The structures of the polymers thus formed were complex and related to the ring‐opening process of the protonated monomer either at the oxygen or nitrogen atoms. The phenolic mechanism also contributed, but its influence decreased with decreasing monomer concentration. Thermal properties of the polymers were also investigated by differential scanning calorimetry and thermogravimetric analysis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3320–3328, 2003
Design and synthesis of highly photopolymerizable styrenyl compounds in solid‐state photoinitiated polymerization
Authors: Furukawa Akira , Imanishi Yukio , Tanihara Masao 
Published: September 2003

AbstractWe designed a new type of styrenyl compound applicable to conventional photopolymerization systems, aiming at the production of polymers with improved mechanical properties, resistance to chemicals, and elevated glass‐transition temperatures (Tg's). A series of styrenyl monomers bearing 2,5‐dithio‐1,3,4‐thiadiazole groups were prepared, and their reactivity was studied in solid‐state photopolymerization initiated by 2‐(4′‐methoxystyryl)‐4,6‐bis(trichloromethyl)‐1,3,5‐triazine. These monomers exhibited much higher polymerization rates than usual, and the final conversion nearly reached completion, despite the relatively high Tg of the solid‐state photopolymerization system. Even at temperatures below Tg, the polymerization proceeded without a ceiling phenomenon. These features were explained by intermolecular interactions between the monomers that induced monomer alignments effective for solid‐state polymerization, large excess free volumes arising from rotation around the methylthio groups, and intramatrix radical migration leading to encounters with the remaining monomers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3227–3242, 2003
Morphology of poly(p‐oxybenzoyl) crystal prepared by direct polycondensation of p‐hydroxybenzoic acid with p‐toluenesulfonyl chloride in pyridine
Authors: Kimura Kunio , Horii Toshiyuki , Yamashita Yuhiko 
Published: September 2003

AbstractPoly(p‐oxybenzoyl) (POB) crystals were prepared with the reaction‐induced crystallization of oligomers during the direct polycondensation of p‐hydroxybenzoic acid (HBA) with p‐toluenesulfonyl chloride (TsCl) and N,N‐dimethylformamide in pyridine. Sheaflike lozenge‐shaped POB crystals were obtained, of which the longer diagonal was 7.0–8.0 μm. The influence of the polymerization condition on the morphology was examined to optimize the preparative condition for the crystals exhibiting the clearest habit, and the favorable condition was determined as the molar ratio of TsCl to HBA of 1.3 and polymerization concentration of 3.0%. The crystals possessed extremely high crystallinity and outstanding thermal stability. The formation mechanism of the crystal was proposed as follows. When the number‐average degree of polymerization of the oligomers exceeded a critical value of about 4, they were precipitated to form the hexagonal lamellae. The crystals were grown very quickly to lozenge‐shaped crystal through screw dislocation with the continuous precipitation of oligomers from the solution. Finally, the further polymerization occurred in the precipitated crystal with developing polymer‐chain packing. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3275–3282, 2003
Crosslinking polymerization leading to interpenetrating polymer network formation. II. Polyaddition crosslinking reactions of poly(methyl methacrylate‐co‐2‐methacryloyloxyethyl isocyanate) with various diols
Authors: Kiguchi Tadahiro , Aota Hiroyuki , Matsumoto Akira 
Published: September 2003

AbstractAs part of our continuing studies concerned with the elucidation of the crosslinking polymerization mechanism leading to interpenetrating polymer network (IPN) formation, in which IPNs consist of both polymethacrylates and polyurethane (PU) networks, this article explores the polyaddition crosslinking reactions of multifunctional poly(methyl methacrylate‐co‐2‐methacryloyloxyethyl isocyanate) [poly(MMA‐co‐MOI)] [MMA/MOI = 90/10] with various diols leading to PU network formation. Thus, the equimolar polyaddition crosslinking reactions of poly(MMA‐co‐MOI) with ethylene glycol (EG), 1,6‐hexane diol, and 1,10‐decane diol (DD) were carried out in N‐methyl pyrrolidone at a 0.25 mol/L isocyanate group concentration at 80 °C. The second‐order rate constants decreased from EG to DD. The deviation of the actual gel point from the theoretical one was smaller from EG to DD. The intrinsic viscosity of resulting prepolymer demonstrated almost no variation with progressing polymerization for the EG system, whereas it gradually increased with conversion for the DD system. Close to the gel point conversion it increased rather drastically for both systems. The swelling ratio of resulting gel was higher from EG to DD. These are discussed mechanistically in terms of the significant occurrence of intramolecular cyclization and intramolecular crosslinking reactions leading to shrinkage of the molecular size. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3243–3248, 2003
Polyimides from isomeric oxydiphthalic anhydrides
Authors: Li Qingxuan , Fang Xingzhong , Wang Zhen , Gao Lianxun , Ding Mengxian 
Published: September 2003

Abstract2,2′,3,3′‐Oxydiphthalic dianhydride (2,2′,3,3′‐ODPA) and 2,3,3′,4′‐ODPA were synthesized from 3‐chlorophthalic anhydride with 2,3‐xylenol and 3,4‐xylenol, respectively. Their structures were determined via single‐crystal X‐ray diffraction. A series of polyimides derived from isomeric ODPAs with several diamines were prepared in dimethylacetamide (DMAc) with the conventional two‐step method. Matrix‐assisted laser desorption/ionization time‐of‐flight spectra showed that the polymerization of 2,2′,3,3′‐ODPA with 4,4′‐oxydianiline (ODA) has a greater trend to form cyclic oligomers than that of 2,3,3′,4′‐ODPA. Both 2,2′,3,3′‐ODPA and 2,3,3′,4′‐ODPA based polyimides have good solubility in polar aprotic solvents such as DMAc, dimethylformamide, and N‐methylpyrrolidone. The 5% weight‐loss temperatures of all polyimides were obtained near 500 °C in air. Their glass‐transition temperatures measured by dynamic mechanical thermal analysis or differential scanning calorimetry decreased according to the order of polyimides on the basis of 2,2′,3,3′‐ODPA, 2,3,3′,4′‐ODPA, and 3,3′,4,4′‐ODPA. The wide‐angle X‐ray diffraction of all polyimide films from isomeric ODPAs and ODA showed some certain extent of crystallization after stretching. Rheological properties revealed that polyimide (2,3,3′,4′‐ODPA/ODA) has a comparatively lower melt viscosity than its isomers, which indicated its better melt processability. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3249–3260, 2003
Effects of clay‐modifying agents on the morphology and properties of poly(methyl methacrylate)/clay nanocomposites synthesized via γ‐ray irradiation polymerization
Authors: Zhang Wei'an , Liang Ying , Luo Wei , Fang Yue'e 
Published: September 2003

AbstractVia γ‐ray irradiation polymerization, poly(methyl methacrylate) (PMMA)/clay nanocomposites were successfully prepared with reactive modified clay and nonreactive clay. With reactive modified clay, exfoliated PMMA/clay nanocomposites were obtained, and with nonreactive clay, intercalated PMMA/clay nanocomposites were obtained. Both results were confirmed by X‐ray diffraction and high‐resolution transmission electron microscopy. PMMA extracted from PMMA/clay nanocomposites synthesized by γ‐ray irradiation had higher molecular weights and narrow molecular weight distributions. The enhanced thermal properties of the PMMA/clay nanocomposites were characterized by thermogravimetric analysis and differential scanning calorimetry. The improved mechanical properties of PMMA/clay were characterized by dynamic mechanical analysis. In particular, the enhancement of the thermal properties of the PMMA/clay nanocomposites with reactive modified clay was much more obvious than that of the PMMA/clay nanocomposites with nonreactive clay. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3218–3226, 2003
Synthesis of poly(tetrahydrofuran)‐b‐polystyrene block copolymers from dual initiators for cationic ring‐opening polymerization and atom transfer radical polymerization
Authors: Bernaerts Katrien V. , Schacht Etienne H. , Goethals Eric J. , Du Prez Filip E. 
Published: September 2003

AbstractA dual initiator (4‐hydroxy‐butyl‐2‐bromoisobutyrate), that is, a molecule containing two functional groups capable of initiating two polymerizations occurring by different mechanisms, has been prepared. It has been used for the sequential two‐step synthesis of well‐defined block copolymers of polystyrene (PS) and poly(tetrahydrofuran) (PTHF) by atom transfer radical polymerization (ATRP) and cationic ring‐opening polymerization (CROP). This dual initiator contains a bromoisobutyrate group, which is an efficient initiator for the ATRP of styrene in combination with the Cu(0)/Cu(II)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine catalyst system. In this way, PS with hydroxyl groups (PS‐OH) is formed. The in situ reaction of the hydroxyl groups originating from the dual initiator with trifluoromethane sulfonic anhydride gives a triflate ester initiating group for the CROP of tetrahydrofuran (THF), leading to PTHF with a tertiary bromide end group (PTHF‐Br). PS‐OH and PTHF‐Br homopolymers have been applied as macroinitiators for the CROP of THF and the ATRP of styrene, respectively. PS‐OH, used as a macroinitiator, results in a mixture of the block copolymer and remaining macroinitiator. With PTHF‐Br as a macroinitiator for the ATRP of styrene, well‐defined PTHF‐b‐PS block copolymers can be prepared. The efficiency of PS‐OH or PTHF‐Br as a macroinitiator has been investigated with matrix‐assisted laser desorption/ionization time‐of‐flight spectroscopy, gel permeation chromatography, and NMR. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3206–3217, 2003
Synthesis and characterization of liquid‐crystalline epoxy and its blend with conventional epoxy
Authors: Sadagopan K. , Ratna D. , Samui A. B. 
Published: September 2003

AbstractTerephthaloyl chloride was reacted with 4‐hydroxy benzoic acid to get terephthaloylbis(4‐oxybenzoic) acid, which was characterized and further reacted with epoxy resin [diglycidyl ether of bisphenol A (DGEBA)] to get a liquid‐crystalline epoxy resin (LCEP). This LCEP was characterized by Fourier transform infrared spectrometry, 1H and 13C NMR spectroscopy, differential scanning calorimetry (DSC), and polarized optical microscopy (POM). LCEP was then blended in various compositions with DGEBA and cured with a room temperature curing hardener. The cured blends were characterized by DSC and dynamic mechanical analysis (DMA) for their thermal and viscoelastic properties. The cured blends exhibited higher storage moduli and lower glass‐transition temperatures (tan δmax, from DMA) as compared with that of the pure DGEBA network. The formation of a smectic liquid‐crystalline phase was observed by POM during the curing of LCEP and DGEBA/LCEP blends. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3375–3383, 2003
Simplified synthesis of carbohydrate‐functional siloxanes via transacetalation. I. Glucose‐functional siloxanes
Authors: Ogawa Takuya 
Published: September 2003

AbstractCarbohydrate‐functional siloxanes (CHFSs) that exhibit high intermolecular interactions and good environmental friendliness have successfully been synthesized by acid‐catalyzed transacetalation between an acetal‐functional siloxane and glucose in dimethylformamide/dioxane mixed solvents. Activated clay has proven to be a good catalyst because of its high activity and its easy removal from the product. Acetal‐functional siloxanes as starting materials can be easily synthesized in good yields by hydrosilylation between SiH‐functional siloxanes and acrolein diethyl acetal. This method has the following advantages: (1) the inexpensive materials used, (2) the simplified process employed, and (3) the high yield achieved. Because the carbohydrate moieties in these materials have the nature of strong intermolecular interactions and are highly hydrophilic, CHFSs exhibit very high bulk viscosities in comparison with the corresponding acetal‐functional siloxanes and good solubilities in polar solvents such as dimethylformamide and dimethyl sulfoxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3336–3345, 2003
Thermosensitive polyalcohols: Synthesis via living cationic polymerization of vinyl ethers with a silyloxy group
Authors: Sugihara Shinji , Hashimoto Kiyotaka , Matsumoto Yuko , Kanaoka Shokyoku , Aoshima Sadahito 
Published: September 2003

AbstractThermosensitive homopolymers and copolymers with hydroxy groups were synthesized via the living cationic polymerization of Si‐containing vinyl ethers. The cationic homopolymerization and copolymerization of five vinyl ethers with silyloxy groups, each with a different spacer length, were examined with a cationogen/Et1.5AlCl1.5 initiating system in the presence of an added base. When an appropriate base was added, the living cationic polymerization of Si‐containing monomers became feasible, giving polymers with narrow molecular weight distributions and various block copolymers. Subsequent desilylation gave well‐defined polyalcohols, in both water‐soluble and water‐insoluble forms. One of these polyalcohols, poly(4‐hydroxybutyl vinyl ether), underwent lower‐critical‐solution‐temperature‐type thermally induced phase separation in water at a critical temperature (TPS) of 42 °C. This phase separation was quite sensitive and reversible on heating and cooling. The phase separation also occurred sensitively with random copolymers of thermosensitive and hydrophilic or hydrophobic units, the TPS values of which in water could be controlled by the monomer feed ratio. The thermal responsiveness of this polyalcohol unit made it possible to prepare novel thermosensitive block and random copolymers consisting solely of alcohol units. One example prepared in this study was a 20 wt % aqueous solution of a diblock copolymer consisting of thermosensitive poly(4‐hydroxybutyl vinyl ether) and water‐soluble poly(2‐hydroxyethyl vinyl ether) segments, which transformed into a physical gel above 42 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3300–3312, 2003
Macrocycles 27: Cyclic aliphatic polyesters of isosorbide
Authors: Kricheldorf Hans R. , Chatti Saber , Schwarz Gert , Krüger Ralf‐P. 
Published: September 2003

AbstractNumerous polycondensations of isosorbide and suberoyl chloride or other aliphatic dicarboxylic acid dichlorides were performed with pyridine as a catalyst and HCl acceptor. The reaction conditions were varied to optimize both the molecular weight and the fraction of cyclic oligo‐ and polyesters. Furthermore, we attempted to obtain the cyclic monomer by catalyzed back‐biting degradation of the molten cyclic polyesters above 220 °C in vacuo. The polyesters were characterized by viscosity and size exclusion chromatographic measurements as well as matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. In selected cases, mixtures of linear and cyclic polyesters were treated with a hot solution of partially methylated β‐cyclodextrin in methanol. This treatment allowed for a selective extraction of the linear chains up to approximately 5000 Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3414–3424, 2003
Synthesis and crosslinking of biphenyl and naphthalene liquid‐crystalline polyethers with pendant full‐saturated and vinyl‐terminated aliphatic chains
Authors: Callau Lourdes , Reina José Antonio , Mantecón Ana 
Published: September 2003

AbstractTwo series of vinyl‐terminated, side‐chain liquid‐crystalline polyethers containing 4,4′‐biphenyl and 2,6‐naphthalene moieties as mesogenic cores with several contents of vinyl crosslinkable groups were synthesized by chemically modifying poly(epichlorohydrin) with mixtures of saturated and vinyl‐terminated mesogenic acids. In most cases the degree of modification was over 90%. The polymers were characterized by chlorine analysis, IR and 1H and 13C NMR spectroscopies, viscometry, size exclusion chromatography/multi‐angle laser light scattering, and thermogravimetric analysis. The liquid‐crystal behavior of all the synthesized polymers was examined by differential scanning calorimetry, polarized optical microscopy (POM), and X‐ray diffraction on mechanically oriented samples. The crosslinking of most polymers was done by peroxide‐type initiators, which generally led to liquid‐crystal elastomers. The mesophase organization was maintained on the crosslinked materials, as confirmed by POM and X‐ray diffraction. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3384–3399, 2003
Living radical polymerization of vinyl chloride initiated with iodoform and catalyzed by nascent Cu0/tris(2‐aminoethyl)amine or polyethyleneimine in water at 25 °C proceeds by a new competing pathways mechanism
Authors: Percec Virgil , Popov Anatoliy V. , Ramirez‐Castillo Ernesto , Weichold Oliver 
Published: September 2003

AbstractThe first example of living radical polymerization of vinyl chloride carried out in water at 25 °C is reported. This polymerization was initiated by iodoform and catalyzed by nascent Cu0 produced by the disproportionation of CuI in the presence of strongly CuII binding ligands such as tris(2‐aminoethyl)amine or polyethyleneimine. The resulting poly(vinyl chloride) was free of structural defects, had controlled molecular weight and narrow molecular weight distribution, contained two ∼CHClI active chain ends, and had a higher syndiotacticity (62%) than the one obtained by conventional free‐radical polymerization at the same temperature (56%). This novel polymerization proceeds, most probably, by a combination of competitive pathways that involves activation by single electron transfer mediated by nascent Cu0 and degenerative chain transfer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3283–3299, 2003