bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glow characterization in direct current plasma polymerization of trimethylsilane
Authors: Yu Q. S. , Huang C. , Yasuda H. K. 
Published: January 2004

AbstractPlasma polymerization of trimethylsilane (TMS) was carried out in a direct current (dc) glow discharge and was investigated by optical photography and plasma diagnostic techniques including optical emission spectroscopy and residual gas analysis. The nature of the glow formed in TMS discharge, which deposited plasma polymers, was significantly different from that of a simple gas such as Ar. In an Ar discharge, the dominant glow was the well known negative glow, which developed at a distinctive distance from the cathode, whereas the cathode surface remained in the dark space. In strong contrast to this situation, in TMS dc discharge the dominant or primary glow was the cathode glow, which appeared at the cathode surface. At a similar location where the Ar negative glow appeared, a very feeble glow as a secondary glow was also observed in TMS glow discharge. The deposition results and plasma diagnosis data evidently indicated that in TMS glow discharge, the cathode glow resulted from the low‐energy electron‐impact dissociation of TMS molecules that creates polymerizable species, but the negative glow was related to nonpolymerizable species such as hydrogen atoms and molecules. In this article, the cathode glow formed in glow discharges of organic compounds was designated as the dissociation glow according to its underlying plasma reactions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1042–1052, 2004
Synthesis and properties of novel Schiff base oligomers based on oligo‐4‐hydroxybenzaldehyde
Authors: Mart H. , Saçak M. , Yürük H. , Şahmetli̇oğlu E. , Vi̇layetoğlu A. R. 
Published: January 2004

AbstractCondensation of oligo‐4‐hydroxybenzaldehyde with aniline, 2‐chloroaniline, 2‐aminophenol, 2‐aminotoluene, 4‐aminotoluene, and 4‐nitroaniline gave the corresponding Schiff base oligomers (OFAP, OKAP, OHAP, OOAP, OTAP, and ONAP, respectively). The products were characterized by 1H NMR, Fourier transform infrared, ultraviolet–visible, and elemental analyses. The number‐average molecular weight, mass‐average molecular weight, and polydispersity index (PDI) values of the Schiff base oligomers were determined. Thermogravimetric analysis was used to compare the thermal stability of the oligomers, which showed the Schiff base oligomers to be resistant to thermooxidative decomposition. Weight loss of 5% and 50% occurred at temperatures of 122 and 475 °C; for OFAP, at 118 and 453 °C; for OKAP, at 182 and 491 °C; for OHAP, at 150 and 452 °C; for OOAP, at 132 and 401 °C; for OTAP, and at 193 and 414 °C for ONAP. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1120–1125, 2004
Thermal behavior of poly(bisphenol A carbonate) in the presence of phosphorus compounds
Authors: Uozumi Toshiya , Kwon Tae Seok , Takeuchi Kazuhiko , Hayashi Teruyuki , Tanaka Masato 
Published: January 2004

AbstractTo clarify the interaction between poly(bisphenol A carbonate) (PBAC) and phosphorus compounds such as triphenylphosphine oxide (TPPO), triphenyl phosphate (TPP), and resorcinol bis(diphenyl phosphate) (RDP), PBAC was heated in the presence of these phosphorus compounds at 240 °C for 2 h, and the resulting polymers were analyzed by 1H NMR spectroscopy and gel permeation chromatography. When heated in the presence of TPPO, the PBAC sample decomposed extensively, resulting in a substantial decrease in molecular weight. On the other hand, thermal treatment in the presence of the phosphates increased the molecular weight. In both cases the molecular weight distribution became narrower. Thermal treatment of PBAC in the presence of both TPPO and TPP allowed us to control the molecular weight with a narrower distribution. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1069–1074, 2004
Very rapid copper‐mediated atom transfer radical polymerization of benzyl methacrylate at ambient temperature
Authors: Munirasu Selvaraj , Dhamodharan Raghavachari 
Published: January 2004

AbstractThe ability to do very rapid bulk atom transfer radical polymerization (ATRP) of benzyl methacrylate using a CuX/PMDETA complex at room temperature was demonstrated in this study. The experimental conditions required to synthesize low‐ and high‐molecular‐weight poly(benzyl methacrylate) with low polydispersity are reported here. The controlled/living nature of the polymerization was demonstrated through kinetic studies, and chain‐extension studies. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1053–1057, 2004
Synthesis of optically active polyurethanes by self‐polyaddition of tyrosine‐based monomers
Authors: Nagai Atsushi , Ishikawa Junichi , Kudo Hiroto , Endo Takeshi 
Published: January 2004

AbstractThe synthesis and self‐polyaddition of the optically active monomers I‐T(L)‐M and I‐T(D)‐M bearing both isocyanate and hydroxyl groups were examined. I‐T(L)‐M and I‐T(D)‐M were synthesized by reactions of L‐ and D‐tyrosine methyl ester, T(L)‐M and T(D)‐M, with di‐tert‐butyltricarbonate, respectively. The self‐polyaddition of I‐T(L)‐M and I‐T(D)‐M proceeded smoothly with triethylamine or tert‐butyllithium as the initiator in tetrahydrofuran, affording the optically active linear polyurethanes poly[I‐T(L)‐M] and poly[I‐T(D)‐M] with specific head‐to‐tail structures, where the number‐average molecular weights ranged from 10,000 to 20,000 in excellent yields. The optical properties suggested the idea that poly[I‐T(L)‐M] and poly[I‐T(D)‐M] should have some higher order structures. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1143–1153, 2004
Solvent effect on chain‐growth polycondensation for aromatic polyethers
Authors: Suzuki Yukimitsu , Hiraoka Shuichi , Yokoyama Akihiro , Yokozawa Tsutomu 
Published: January 2004

AbstractThe polycondensation of potassium 5‐cyano‐4‐fluoro‐2‐octylphenolate (1b) was carried out in the presence of 4‐fluoro‐4′‐trifluoromethylbenzophenone (2) as an initiator for chain‐growth polycondensation in a variety of solvents, and the chain‐growth nature of this polymerization was found to depend on the kind of solvent. In the polycondensation of 1b with 2 in sulfolane at 150 °C, the MALDI‐TOF mass spectra of poly1b showed only one series of peaks due to poly1b attached with the initiator 2 unit, and the 19F NMR spectra indicated that the ratios of the initiator unit to the end group were 1.0. Therefore, chain‐growth polycondensation occured in this condition. On the other hand, the polycondensation in THF, quinoline, DMI, tetraglyme at 150 °C gave poly1b with broad molecular weight distributions, and the MALDI‐TOF mass spectra showed two series of peaks resulting from both chain‐growth and step‐growth polycondensations. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1198–1207, 2004
Preparation and characterization of chiral polyacrylates end‐capped with bornyl groups in the side chains
Authors: Liu Jui‐Hsiang , Hsieh Ching‐Dong , Wang Hong‐Yu 
Published: January 2004

AbstractChiral polyacrylates with bornyl end‐capped side chains with four kinds of mesogenic moieties (azobenzene, biphenyl, benzoyloxy biphenyl, and phenyl benzoate) were prepared. The phase properties of the polymers were investigated with X‐ray diffraction, differential scanning calorimetry, and polarizing optical microscopy. The thermogravimetric characteristics, the glass‐transition temperatures and weight‐average molecular weights, of the homopolymers were evaluated. The optical properties of the synthesized polymers in diluted solutions and in the thin‐film state were also evaluated. The optical behavior of the composite films upon photoirradiation was investigated through the change in the transmittance of the probe light triggered by ultraviolet (365‐nm) irradiation. Ultraviolet irradiation and heat treatment caused a reversible intensity change of the probe light at λ = 400 nm. The shrinkage of the photoisomerization of the composite films was also investigated with atomic force microscopy. A spot contraction appeared on the surface when it was irradiated with a laser light spot. The contraction was recovered by heat treatment at 80 °C for 10 min. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1075–1092, 2004
Tropone‐containing π‐conjugated polymers: Annulation of tropone onto benzene ring in the conjugated polymer
Authors: Nishioka Naomi , Takagi Koji , Kinoshita Takatoshi , Kunisada Hideo , Yuki Yasuo 
Published: January 2004

AbstractTropone‐fused, various π‐conjugated polymers (P2–P5) were synthesized by the palladium‐catalyzed coupling reaction of 1,4‐dibromo‐6,8‐dimethyl‐7H‐benzocyclohepten‐7‐one with aromatic divinyl, diboronic acid, and diethynyl compounds. The molecular orbital calculation of the model compounds was performed to discuss effective conjugation length of the repeating unit of the polymers. The absorption spectra of phenylenevinylene‐type polymers shifted to longer wavelengths than the model compounds by about 60 nm. They exhibited green fluorescence [λmax(em) = 544 and 561 nm]. The absorption spectrum of a phenylene‐type polymer blueshifted by 10 nm; however, that of a phenyleneethynylene‐type polymer redshifted by 83 nm as compared with their model compounds. They showed fluorescence with peak maxima at 457 and 489 nm, respectively. As a result, the absorption spectra of phenylene‐ and phenylenevinylene‐type polymers blueshifted, but that of a phenyleneethynylene‐type polymer redshifted by the annulation of tropone onto a benzene ring in the conjugated polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1208–1215, 2004
Dendritic homopolymers and block copolymers: Tuning the morphology and properties
Authors: Trollsås Mikael , Atthoff Björn , Claesson Hans , Hedrick James L. 
Published: January 2004

AbstractThe synthesis and characterization of dendritic homopolymers and block copolymers of ϵ‐caprolactone and lactide (L‐lactide and racemic lactide) were performed with multifunctional initiators in combination with living polymerization and the selective placement of branching junctures in a divergent growth strategy. A hexahydroxy‐functional 2,2‐bis(hydroxymethyl) propionic acid derivative was used as an initiator for the stannous‐2‐ethylhexanoate‐catalyzed living ring‐opening polymerization of ϵ‐caprolactone, L‐lactide, and racemic L,D‐lactide. Branching junctions at the chain ends were introduced with benzylidene‐protected 2,2‐bis(hydroxymethyl) propionic acid. Subsequent generations were then polymerized, after deprotection, from these star‐shaped macroinitiators. Successive chain end capping and initiation produced three generations of polymers with molecular weights in excess of 130,000 g/mol and narrow polydispersities (<1.20). It was possible to prepare diblock and triblock copolymers with phase‐separated morphologies, and with L‐lactide or D,L‐lactide, semicrystalline and amorphous morphologies were demonstrated. The polymers were characterized by 1H NMR, 13C NMR, size exclusion chromatography, and differential scanning calorimetry. The compositions of the block copolymers and the conformational structures of the optically active polymers were also confirmed by optical rotation measurements. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1174–1188, 2004
Synthesis and properties of soluble trifluoromethyl‐substituted polyimides containing laterally attached p‐Terphenyls
Authors: Hsiao Sheng‐Huei , Chang Yu‐Hui 
Published: January 2004

AbstractA new fluorinated diamine monomer, 2′,5′‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐p‐terphenyl, was synthesized from the chloro‐displacement of 2‐chloro‐5‐nitrobenzotrifluoride with the potassium phenolate of 2,5‐diphenylhydroquinone, followed by hydrazine palladium‐catalyzed reduction. A series of trifluoromethyl‐substituted polyimides containing flexible ether linkages and laterally attached side rods were synthesized from the diamine with various aromatic dianhydrides via a conventional two‐step process. The inherent viscosities of the poly(amic acid) precursors were 0.84–1.26 dL/g. All the polyimides afforded flexible and tough films. The use of 4,4′‐oxydiphthalic anhydride and 2,2′‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride produced essentially colorless polyimide films. Most of the polyimides revealed an excellent solubility in many organic solvents. The glass‐transition temperatures of these polyimides were recorded between 254 and 299 °C by differential scanning calorimetry, and the softening temperatures of the polymer films stayed in the range of 253–300 °C according to thermomechanical analysis. The polyimides did not show significant decomposition before 500 °C in air or under nitrogen. These polyimides also showed low dielectric constants (2.83–3.34 at 1 MHz) and low moisture absorption (0.4–2.2%). For a comparative study, a series of analogous polyimides based on the nonfluorinated diamine 2′,5′‐bis(4‐aminophenoxy)‐p‐terphenyl were also prepared and characterized. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1255–1271, 2004
Radiochemical aging of ethylene–propylene–diene monomer elastomers. I. Mechanism of degradation under inert atmosphere
Authors: Rivaton A. , Cambon S. , Gardette J.‐L. 
Published: January 2004

AbstractThis article is devoted to the study of electron‐beam‐induced degradation under argon atmosphere of an ethylene–propylene–diene monomer (EPDM, based on 5‐ethylidene 2‐norbornene) and an ethylene–propylene rubber (EPR) containing the same molar ratio of ethylene/propylene. The chemical structure modifications of polymeric samples were analyzed by ultraviolet–visible and IR spectroscopies. Crosslinking reactions were deduced by measuring the changes in gel fraction and the degree of swelling in n‐heptane. Irradiation of EPDM and EPR created trans‐vinylene, vinyl, vinylidene, and dienic‐type unsaturations. The radiochemical yields for unsaturation formations in EPDM and EPR were similar. Degradation also involved crosslinking and the production of molecular hydrogen. The comparison between EPDM and EPR showed that the diene (in which a double bond is consumed with a high radiochemical yield) contributes to the increase in rate and intermolecular bridges density. Mechanisms are proposed to account for the main routes of EPDM degradation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1239–1248, 2004
Illusions in advanced cancer: The effect of belief systems and attitudes on quality of life
Authors: Beadle G.F. , Yates P.M. , Najman J.M. , Clavarino A. , Thomson D. , Williams G. , Kenny L. , Roberts S. , Mason B. , Schlect D. 
Published: January 2004

AbstractPatients with advanced cancer frequently express positive attitudes and can be unduly optimistic about the potential benefits of treatment. In order to evaluate an illusory domain in the context of advanced cancer, we developed a scale of will to live and characterized the beliefs that patients held about the curability of their cancer, and how committed they were to using alternative treatments. A measure of quality of life was used as the dependent variable in order to assess the association between these attributes. After a preliminary exploration confirmed the presence of an illusory domain, these concepts were prospectively tested in 149 ambulant patients with advanced cancer who attended for palliative systemic treatment, radiation treatment or supportive care. The scale of global quality of life was reliable (Cronbach's alpha coefficient 0.72). The distribution of the scores of will to live was skewed, with no respondent scoring poorly, and the scale was reliable (Cronbach's alpha coefficient 0.82). The scale of belief in curability showed diverse beliefs. In some cases, there was a discrepancy between respondents' beliefs in curability and what they believed to be the report by their doctors. There was also an association between a committed use of alternative treatments and a belief in the curability of the cancer (p<0.001). In a multiple regression analysis, both will to live and performance status remained associated with better quality of life scores after adjustment for other relevant variables (p<0.05 and <0.001, respectively). These results suggest that positive illusory beliefs can be measured and are an important component of adaption for some patients with advanced cancer. Furthermore, this illusory domain may influence the perception and measurement of quality of life. Copyright © 2003 John Wiley & Sons, Ltd.
Psychosocial functioning in women who have undergone bilateral prophylactic mastectomy
Authors: Metcalfe Kelly A. , Esplen Mary Jane , Goel Vivek , Narod Steven A. 
Published: January 2004

AbstractThe purpose of this study was to determine the current psychosocial functioning of women who had previously had a bilateral prophylactic mastectomy. Women in the province of Ontario who had undergone prophylactic mastectomy between 1991 and 2000 were asked to complete questionnaires that assessed psychological distress, sexual activity, overall satisfaction with decision to have a prophylactic mastectomy, and body image. Ninety‐seven percent of the women were satisfied with their decision to have a prophylactic mastectomy, but young women (<50 years) were less likely to report satisfaction than older women (p=0.001). Women with a strong family history of breast cancer or a BRCA1 or BRCA2 mutation experienced more cancer‐related distress than those with a limited family history. Women who had reconstruction following mastectomy reported higher levels of satisfaction with general body shape and appearance than those without reconstruction. In conclusion, the majority of women were satisfied with their decision to undergo prophylactic mastectomy and were not experiencing abnormal levels of psychological distress, low levels of sexual activity, or difficulties with body image. Copyright © 2003 John Wiley & Sons, Ltd.
Myosin flexibility: Structural domains and collective vibrations
Authors: Navizet Isabelle , Lavery Richard , Jernigan Robert L. 
Published: January 2004

AbstractThe movement of the myosin motor along an actin filament involves a directed conformational change within the cross‐bridge formed between the protein and the filament. Despite the structural data that has been obtained on this system, little is known of the mechanics of this conformational change. We have used existing crystallographic structures of three conformations of the myosin head, containing the motor domain and the lever arm, for structural comparisons and mechanical studies with a coarse‐grained elastic network model. The results enable us to define structurally conserved domains within the protein and to better understand myosin flexibility. Notably they point to the role of the light chains in rigidifying the lever arm and to changes in flexibility as a consequence of nucleotide binding. Proteins 2004;54:000–000. © 2003 Wiley‐Liss, Inc.
The number of protein folds and their distribution over families in nature
Authors: Liu Xinsheng , Fan Ke , Wang Wei 
Published: January 2004

AbstractCurrently, of the 106 known protein sequences, only about 104 structures have been solved. Based on homologies and similarities, proteins are grouped into different families in which each has a structural prototype, namely, the fold, and some share the same folds. However, the total number of folds and families, and furthermore, the distribution of folds over families in nature, are still an enigma. Here, we report a study on the distribution of folds over families and the total number of folds in nature, using a maximum probability principle and the moment method of estimation. A quadratic relation between the numbers of families and folds is found for the number of families in an interval from 6000 to 30,000. For example, about 2700 folds for 23,100 families are obtained, among them about 33 superfolds, including more than 100 families each, and the largest superfold comprises about 800 families. Our results suggest that although the majority of folds have only a single family per fold, a considerably larger number of folds include many more families each than in the database, and the distribution of folds over families in nature differs markedly from the sampled distribution. The long tail of fold distribution is first estimated in this article. The results fit the data for different versions of the structural classification of proteins (SCOP) excellently, and the goodness‐of‐fit tests strongly support the results. In addition, the method of directly “enlarging” the sample to the population may be useful in inferring distributions of species in different fields. Proteins 2004;54:000–000. © 2003 Wiley‐Liss, Inc.
Splice variants: A homology modeling approach
Authors: Furnham Nicholas , Ruffle Stuart , Southan Christopher 
Published: January 2004

AbstractSplice variants play an important role within the cell in both increasing the proteome diversity and in cellular function. Splice variants are also associated with disease states and may play a role in their etiology. Information about splice variants has, until now, mostly been derived from the primary transcript or through cellular studies. In this study information from the transcript and other studies is combined with tertiary structure information derived from homology models. Through this method we have determined that it is possible to effectively model splice variants. Forty models of splice variants for fourteen proteins were produced. Analysis of the models shows that deletions produce superior model validation values. Additions to sequences where there is little homology become increasingly difficult to model with increasing sequence length. Many of the splicing events are associated with post‐translational modification either in the N‐terminal region by changing the signal peptide or by affecting the number or availability of glycosylation sites. Often the alternative exon combinations are associated with loss or gain of whole structural units, as opposed to just changing small loop regions. Losing part of the secondary structure may destabilize neighboring parts of the same secondary structure. Detailed analysis is given of four biomedically relevant proteins (Beta‐site Amyloid Precursor Protein Cleaving enzyme (BACE), Interleukin‐4, Frataxin and Hereditary hemochromatosis protein) and their associated splice variant models. The visualization of these possible structures provides new insights about their functionality and the possible etiology of associated diseases. Proteins 2004;54:000–000. © 2003 Wiley‐Liss, Inc.
Aromatic side‐chain interactions in proteins: Near‐ and far‐sequence Tyr‐X pairs
Authors: Meurisse Rita , Brasseur Robert , Thomas Annick 
Published: January 2004

AbstractIn the present study, an extensive analysis of the aromatic Tyr‐X interactions is performed on a data set of 593 PDB structures, X being Phe, His, Tyr, and Trp. The nonredundant Tyr‐X pairs (2645) were retained and separated by both the residue distance in the sequence and the secondary structures they bridge. Similar to the Phe‐X and His‐X pairs, the far‐sequence Tyr‐X pairs (X partner > five apart in the sequence: 74%) show comparable secondary structures and conformers for either type of X partner, in contrast with the near‐sequence Tyr‐X pairs (26%). As the Phe‐X pairs, the near‐sequence Tyr‐X pairs stabilize secondary structures, mainly the α‐ helices (positions 1, 3, and 4) and the β‐strands (position 2). Like the Phe‐X and His‐X pairs, most far‐sequence Tyr‐X pairs (34%) bridge β‐strands and only 11% bridge helices. As for the Phe‐X and the His‐X pairs, the X partners of the far‐sequence Tyr‐X pairs are frequently “above” the tyrosine ring with tilted and normal rings, whereas the X partner of the near‐sequence Tyr‐X pairs gradually moves from the “aside” to the “above” location, together with a progressive decrease of normal and increase of parallel rings, respectively. Unlike the His‐X pairs, the interactions of the hetroatom in Tyr‐X pairs are only favored with a sequence position +4 and over, owing to the spatial accessibility of the heteroatom. Proteins 2004;54:000–000. © 2003 Wiley‐Liss, Inc.