bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermal and ionic‐conductive behaviors of liquid crystalline polymers with alkali metal salt
Authors: Akachi Yosuke , Kawamura Kenji , Koide Naoyuki 
Published: August 2002

AbstractIn order to investigate the relationship between ionic conductivity and liquid crystallinity, we prepared the main‐chain type polyester having 1,4‐bisstyrylbenzene units and ethyleneoxide chain in the repeating unit. The main‐chain type polyester with lithium salt at the ratio of 0.04 per polymer repeating unit exhibited a smectic phase. However, the polyester with lithium salt (0.11) showed a nematic phase. The ionic conductivity of the polyester with lithium salt increased with increasing lithium salt concentration.The trans‐type polyester exhibited a liquid crystalline phase, while the cis‐type polyester did not show any mesophase. We found that the ionic conductivity of the trans‐type polyester with lithium salt (0.11) was larger than that of the cis‐type polyester with lithium salt (0.11).However, a liquid crystalline phase was found in the side‐chain type polyether with alkoxy chain length of below 12. A smectic phase was induced for the non‐mesomorphic polyethers with lithium salt. The layer spacing of the smectic A phase for the non‐mesomorphic polyether with lithium salt decreased from 55 to 41 Å with increasing temperature. The ionic conductivity of the polyether with lithium salt increased with decreasing the layer spacing. Copyright © 2001 John Wiley & Sons, Ltd.
Low incidence of SV40‐like sequences in ependymal tumours
Authors: Reuther F. J. , Löhler J. , Herms J. , Hugo H.‐H. , Schindler C. , Leithäuser F. , Melzner I. , Möller P. , Scheil S. 
Published: August 2002

AbstractBetween 1955 and 1963, millions of children and adults were exposed to SV40‐contaminated poliovirus vaccines. The oncogenic potential of this polyomavirus was revealed when intracerebral inoculation of SV40 into newborn hamsters resulted in the development of ependymomas and choroid plexus papillomas. Subsequently, SV40‐like sequences were repeatedly detected in human ependymomas with broadly ranging incidence rates of 7–90%. Most epidemiological studies, however, have not described an increased occurrence of ependymomas. To gain more data on this controversial issue, this study examined 62 archived ependymal tumours from 31 children and 31 adults who underwent surgery between 1990 and 1999. Only three (5%) of the tumours – including 24 classical, 20 anaplastic, and 12 myxopapillary ependymomas; one subependymoma; and five ependymoblastomas – revealed subgenomic SV40 sequences. None of the ependymomas in patients born between 1920 and 1960 demonstrated SV40‐like sequences. The positive tumours represent 7% of grade II and III ependymomas (two paediatric and one adult tumour). DNA sequencing of the PCR product revealed identical sequences of SV40 in the positive ependymal tumours. Compared with the results from other countries, this incidence rate is relatively low. Therefore, it seems likely that significant differences between individual countries exist regarding the prevalence of SV40‐positive ependymomas. These differences may reflect different degrees of exposure to SV40‐contaminated polio vaccine. Copyright © 2001 John Wiley & Sons, Ltd.
Differences in in vitro invasive capacity induced by differences in Ki‐Ras protein mutations
Authors: Al‐Mulla Fahd , MacKenzie Elaine M. 
Published: August 2002

AbstractThe p21 proteins encoded by N‐, Ki‐, and H‐ras are small guanine nucleotide‐binding proteins that act as switches in several signal transduction pathways. Recently, evidence has been accumulating to suggest that valine‐12 mutation in the Ki‐Ras protein is associated with lung and colorectal tumours that are more aggressive than those carrying aspartate‐12 mutation. The purpose of this study was to determine whether cells transfected with different Ki‐ras codon‐12 mutants have different biological behaviours in vitro that could reflect the differences in behaviour in vivo. For that reason, Rat‐1 fibroblasts transfected with the valine‐12 or aspartate‐12 mutant or the wild‐type Ki‐ras gene were assessed in terms of in vitro invasion, transformation, and VEGF production. Both mutants demonstrated equal abilities to transform Rat‐1 cells and induce VEGF production, while cells transfected with wild‐type Ki‐Ras failed to do so. Most significantly, the valine‐12 mutants demonstrated a greater ability to invade Matrigel than cells expressing the aspartate‐12 mutant or wild‐type Ki‐Ras proteins. This study complements previous experimental data that specific Ras mutations differ in their effects in vivo and shows, for the first time, a significant difference in Matrigel invasion in vitro. The precise mechanisms behind these biological differences in vivo and in vitro should now be investigated. Copyright © 2001 John Wiley & Sons, Ltd.
A water‐based triphenyltetrazolium chloride method for the evaluation of green plant tissue viability
Authors: Lin Chin Ho , Chen Bing Shiunn , Yu Chih Wen , Chiang Shih Wen 
Published: August 2002

AbstractA water‐based 2,3,5‐triphenyltetrazolium chloride (TTC) partitioning method using n‐hexane for the evaluation of green plant tissue viability has been developed. Conventionally, the reduction of TTC to insoluble red‐coloured triphenylformazan (TPF) has been used to detect seed, bud, leaf and cultured cell viability. However, the 95% ethanol used to extract TPF also extracts various pigments, such as chlorophyll, from plant tissues which interfere with the absorption of TPF at 485 nm. This new water‐based method improves upon the current method by eliminating the interfering pigments in the hexane layer, and by minimising the non‐enzymatic oxidation of the sample. When used to evaluate the tissue viability of chill‐stressed waxapple (Syzygium samarangense) plants, the refined method had a greater sensitivity than the electrolyte leakage method and thus provided a more precise assessment for the physiological state of various plant tissues. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitative determination of liriodenine and moupinamide in five species of Mollinedia by high performance liquid chromatography
Authors: Moreira Davyson de Lima , Leitão Gilda Guimarães 
Published: August 2002

AbstractA simple method for the resolution and subsequent quantitative determination of liriodenine and moupinamide in Mollinedia species was developed using reversed‐phase HPLC based on an octadecyl silane‐packed column eluted with gradients of methanol and water. Copyright © 2001 John Wiley & Sons, Ltd.
Polar lipid and fatty acid distribution in carotenolipoprotein complexes extracted from sea buckthorn fruits
Authors: Pintea Adela , Marpeau Anne , Faye Monique , Socaciu Carmen , Gleizes Michel 
Published: August 2002

AbstractSea buckthorn (Hippophae rhamnoides L., fam. Elaeagnaceae) fruits are rich in pigments and lipoproteins located in membranes and the fleshy mesocarp. In spite of many reports concerning the neutral lipids in the mesocarp, no data about the polar lipids and their fatty acid composition are available even though they play important structural and physiological roles in cell membranes and may offer interesting applications as emulsifiers and nutrients in cosmetic preparations. Carotenolipoprotein complexes are located particularly in fruit membranes where polar lipids may function as bridge compounds between the polar (protein) and non‐polar (carotenoid) moieties. The fatty acid compositions of total and individual polar lipids separated from carotenolipoprotein complexes were determined by HPTLC and GC. The polar lipids included 61% phospholipids and 39% galactolipids, which contained mainly 16:0, 16:1 (9c), 18:1 (9c), 18:1 (11c) and 18:2 (9c, 12c) fatty acids. Almost all polar lipids showed high ratios of 16:0/16:1 (11c) and 18:1 (9c)/18:1 (11c), and higher quantities of 18 carbon unsaturated fatty acids than of the saturated analogue. Galactolipids proved to be richest in 18:1 (9c) and 18:3 (9c, 12c, 15c) fatty acids, while phospholipids contained higher concentrations of 16:0 and 18:1 (9c). Copyright © 2001 John Wiley & Sons, Ltd.
Method for the extraction of the volatile compound salicylic acid from tobacco leaf material
Authors: Verberne Marianne C. , Brouwer Nynke , Delbianco Federica , Linthorst Huub J. M. , Bol John F. , Verpoorte Robert 
Published: August 2002

AbstractSalicylic acid (SA) is a signalling compound in plants which is able to induce systemic acquired resistance. In the analysis of SA in plant tissues, the extraction recovery is often very low and variable. This is mainly caused by sublimation of SA, especially during evaporation of organic solvents. Techniques have been designed in order to overcome this problem. In the first part of the extraction procedure, sublimation of SA was prevented by addition of 0.2 M sodium hydroxide. At a later stage of the extraction procedure, sublimation of SA during solvent evaporation was controlled by the addition of a small amount of HPLC eluent. In this way, recoveries in the range of 71–91% for free SA and 65–79% for acid‐hydrolysed SA were obtained. Recoveries could be further optimised by the use of an internal standard to correct for volume changes after the addition of the HPLC eluent. Copyright © 2001 John Wiley & Sons, Ltd.
Comparative differential scanning calorimetric analysis of vegetable oils: I. Effects of heating rate variation
Authors: Tan C. P. , Man Y. B. Che 
Published: August 2002

AbstractThe melting curves of 11 vegetable oils have been characterised. Vegetable oil samples that were cooled at a constant rate (5°C/min) from the melt showed between one and seven melting endotherms upon heating at four different heating rates (1, 5, 10 and 20°C/min) in a differential scanning calorimeter (DSC). Triacylglycerol (TAG) profiles and iodine value analyses were used to complement the DSC data. Generally, the melting transition temperature shifted to higher values with increased rates of heating. The breadth of the melting endotherm and the area under the melting peak also increased with increasing heating rate. Although the number of endothermic peaks was dependent on heating rate, the melting curves of the oil samples were not straightforward in that there was no correlation between the number of endothermic peaks and heating rates. Multiple melting behaviour in DSC experiments with different heating rates could be explained by: (1) the melting of TAG populations with different melting points; and (2) TAG crystal reorganisation effects. On the basis of the corollary results obtained, vegetable oils and fats may be distinguished from their offset‐temperature (Toff) values in the DSC melting curves. The results showed that Toff values of all oil samples were significantly (p < 0.01) different in the melting curves scanned at four different scanning rates. These calorimetric results indicate that DSC is a valuable technique for studying vegetable oils. Copyright © 2002 John Wiley & Sons, Ltd.
Prenatal diagnosis of pyruvate dehydrogenase deficiency using magnetic resonance imaging
Authors: Robinson Julian N. , Norwitz Errol R. , Mulkern Robert , Brown Stephen A. , Rybicki Frank , Tempany Clare M. C. 
Published: August 2002

AbstractIntroductionPyruvate dehydrogenase deficiency is an inherited inborn error of metabolism associated with early neonatal death and long‐term neurologic sequelae in survivors. Prenatal diagnosis currently relies on isolation of fetal cells for subsequent genetic and/or biochemical studies. Magnetic resonance imaging and magnetic resonance spectroscopy have been used on occasion for both postnatal diagnosis and management of pyruvate dehydrogenase deficiency. We illustrate a case in which these non‐invasive modalities also prove useful for prenatal diagnosis of this condition.CaseA 31‐year‐old multipara with a history of two prior infants affected with pyruvate dehydrogenase deficiency presented with a spontaneous dichorionic, diamniotic twin pregnancy. Magnetic resonance imaging and magnetic resonance spectroscopy were performed on both fetuses. Magnetic resonance imaging of the presenting (male) fetus demonstrated mild ventriculomegaly, increased extracerebrospinal fluid, and decreased cortical sulcation and gyration. The non‐presenting (female) fetus was structurally normal. Magnetic resonance spectroscopy spectra were obtained for both fetuses, and were normal. The diagnosis of pyruvate dehydrogenase deficiency was made in the presenting fetus after delivery on the basis of subsequent mortality from severe lactic acidosis.ConclusionPrenatal MR imaging of the fetal brain can be used for prenatal diagnosis in fetuses at risk for pyruvate dehydrogenase deficiency. Prenatal MR spectroscopy, although technically feasible, does not appear to have a role in the prenatal diagnosis of this condition. Copyright © 2001 John Wiley & Sons, Ltd.
Invasive assessment of fetal renal abnormalities: urinalysis, fetal blood sampling and biopsy
Authors: Nicolini Umberto , Spelzini Federico 
Published: August 2002

AbstractThere are a number of potential biochemcial markers that may have some role in predicting renal function postnatally. These include urinary sodium, calcium and β2‒microglobulin. The latter may also be measured in fetal serum. However, the accuracy of these parameters at a point in time is far from perfect as urinary tract obstruction is a progressive disease which may be best defined by repeated observations throughout pregnancy. Copyright © 2001 John Wiley & Sons, Ltd.
Ethical issues in pharmacoepidemiological research in Belgium
Authors: Verstraete Alain G. , Vander Stichele Robert H. , Deliens Luc H. J. 
Published: August 2002

AbstractPurposeTo illustrate the ethical issues faced in pharmacoepidemiological research in Belgium.MethodsThe experience with three studies is described. The studies concern the use of drugs for euthanasia in medical practice, cytomegalovirus infection in single solid organ transplants and a comparison of benzodiazepine use in the general population and in acute self‐poisoning.ResultsWith some creativity, it was possible to meet the requirements of the ethics committees and the law on computer databases, e.g. by bringing data validation closer to the data entry process, by assuring anonymity in mailing procedures, or by deleting identification labels as soon as they are no longer necessary.ConclusionsThe existing juridical vacuum has not really impeded pharmacoepidemiological research. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and in vitro degradation properties of poly[(tetramethylene carbonate)‐co‐(sebacic anhydride)]
Authors: Xiao Congming , Zhu K J 
Published: August 2002

AbstractA novel poly[(tetramethylene carbonate)‐co‐(sebacic anhydride)] (PTCSA) was synthesized by the melt polycondensation reaction of sebacic acid (SA) and the dicarboxylic acid which derived from oligo(tetramethylene carbonate) diol via the corresponding mixed anhydrides. The copolymer structure was confirmed by means of FTIR and [1H] NMR spectra. DSC analysis showed PTCSA was semicrystalline polymer which had low Tg (<−30 °C). The measurements of contact angles indicated that the hydrophobicity of PTCSA increased as the content of carbonate segments increased. In vitro degradation of PTCSA was performed in lipase‐free and lipase‐containing phosphate‐buffer saline (0.1 M, pH 7.4) at 37 °C. It was found that the degradation rate of PTCSA increased with the amount of SA. After 7 days of degradation in lipase‐free phosphate‐buffer saline, the weight loss of PTCSA was 74, 49 and 22% for 80, 58 and 32 mol% SA contained samples, respectively. The weight loss of PTCSA increased rapidly in the first week, then slowed down but could be greatly enhanced by lipase. After 3 weeks of degradation with or without lipase, the weight loss of PTCSA was 66 and 52% for 58 mol% SA‐containing samples, respectively. The size of the samples was gradually reduced and the surface became coarse. It was also found that the molecular weights of the outer layer were lower than those of the inner layer of the samples after degradation. The results suggested that PTCSA was some kind of biodegradation and surface‐erosion material.© 2001 Society of Chemical Industry
Novel synthesis of branched polystyrenes by quasi‐living radical copolymerization using photofunctional inimer
Authors: Ishizu Koji , Mori Akihide 
Published: August 2002

AbstractBranched polystyrenes were prepared by quasi‐living radical copolymerization of N,N‐diethylaminodithiocarbamoylmethylstyrene (inimer: DTCS) with styrene under UV irradiation. DTCS monomers play an important role in this copolymerization system as an inimer capable of initiating living radical polymerization of the vinyl group. Two monomers (DTCS and styrene) showed equal reactivity toward both propagating species, and the copolymer composition was the same as the comonomer feed. This result means that both the branching and chain length of the hyperbranched molecules can be controlled statistically by the feed monomer ratios. The compact nature of the branched macromolecules is demonstrated by viscosity measurements compared to the linear analogues.© 2001 Society of Chemical Industry
Synthesis and characterization of novel polymers derived from gluconolactone
Authors: Narain Ravin , Jhurry Dhanjay 
Published: August 2002

AbstractA novel synthesis of vinyl monomers derived from D‐gluconolactone, an interesting precursor obtained from D‐glucose, is reported. The derivatization of D‐gluconolactone is carried out by first reacting methacrylic acid with a diamine in water, followed by in situ amidation of the sugar compound. Three monomers containing different lengths of alkylamido groups between vinyl and sugar residues, have thus been obtained and homopolymerized with various free‐radical initiators. The resulting polymers were analysed by viscometry and were found to exhibit polyelectrolyte behaviour. Their structures were confirmed by NMR and consist of a predominantly syndiotactic structure. Copolymerization of the gluconamidoalkyl ammonium methacrylates with other hydrophilic monomers such as methacrylamide and vinylpyrrolidone was also achieved.© 2001 Society of Chemical Industry
Sorting out successful failures: Exploratory analyses of factors associated with academic and behavioral outcomes of retained students
Authors: Ferguson Phillip , Jimerson Shane R. , Dalton Michael J. 
Published: August 2002

AbstractThis prospective longitudinal study followed a sample of 106 kindergarten students through 11th grade examining the effects of family characteristics, school readiness, socialization, and student demographics on academic achievement and behavioral adjustment outcomes. These educational outcomes were contrasted among four groups consisting of: 1) early grade retainees; 2) transitionally placed retained students; 3) students recommended for transitional placement, but promoted; and 4) regularly promoted students. While previous studies examining the efficacy of early grade retention focus exclusively on between‐group comparisons, this study examines the family and individual characteristics of successful and unsuccessful retained students by including both between‐group and within‐group effects on academic and behavioral outcomes. The results of this study demonstrate that retained students' initial school readiness, socioeconomic status, mother's level of education, parental value of education, kindergarten personal‐social functioning, and chronological age are distinctly associated with subsequent academic or behavioral outcomes. Variables associated with relative educational success following early failure are delineated and research implications are discussed. © 2001 John Wiley & Sons, Inc.
Alternating π‐conjugated copolymer of dithiafulvene with 2,2′‐bipyridyl units
Authors: Naka Kensuke , Uemura Takashi , Chujo Yoshiki 
Published: August 2002

AbstractA π‐conjugated polymer containing a dithiafulvene unit and a bipyridyl unit was prepared by cycloaddition polymerization of aldothioketene derived from 5,5′‐diethynyl‐2,2′‐bipyridine. Ultraviolet–visible (UV–vis) absorption spectra showed that the π‐conjugation system of the polymer expanded more effectively than that of a benzene analogue of poly(dithiafulvene) obtained from 1,4‐diethynylbenzene. Cyclic voltammetry measurements indicated that the dithiafulvene–bipyridyl polymer was a weaker electron‐donor polymer than the benzene analogue. These results supported the idea that the incorporation of the electron‐accepting bipyridyl moiety into conjugated poly(dithiafulvene) induced an intramolecular charge‐transfer (CT) effect between the units. Treatment of the dithiafulvene–bipyridyl polymer with bis(2,2′‐bipyridyl)dichlororuthenium (II) [Ru(bpy)2Cl2] afforded a ruthenium–polymer complex. A cyclic voltammogram of the complex showed broad redox peaks, which indicated electronic interaction between the dithiafulvene and tris(bipyridyl) ruthenium complex. The dithiafulvene–bipyridyl polymer formed CT complexes with 7,7,8,8‐tetracycanoquinodimethane (TCNQ) in dimethyl sulfoxide. The UV–vis absorption indicated that the resulting CT complex contained anion radical of TCNQ and partially charge‐transferred TCNQ. The polymer showed an unusually high electrical conductivity of 3.1 × 10−4 S/cm in its nondoped state due to the effective donor–acceptor interaction between the bipyridine unit and the dithiafulvene unit. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4083–4090, 2001
Polymer science with transition metals and main group elements: Towards functional, supramolecular inorganic polymeric materials
Authors: Manners Ian 
Published: August 2002

AbstractInorganic polymers are relatively unexplored because the efficient formation of macromolecular chains from atoms of transition metals and main group elements has presented a synthetic challenge. Nevertheless, these materials offer exciting opportunities for accessing properties that are significantly different from and which therefore complement those available with the well‐established organic systems. Inorganic block copolymers are of particular interest for the generation of functional, nanoscale supramolecular architectures and hierarchical assemblies using self‐assembly processes. This article focuses on research in my group over the past decade, which has targeted the development of new and controlled routes to inorganic polymers and their subsequent use in forming supramolecular materials as well as studies of their properties and applications. The use of ring‐opening polymerization (ROP) and transition‐metal‐catalyzed polycondensation approaches are illustrated. Controlled ROP procedures have been developed that allow access to polyferrocene block copolymers that self‐assemble into interesting nanoscopic architectures such as cylinders and superstructures such as flowers. The future prospects for inorganic polymer science are discussed, and a growing emphasis on the study of supramolecular inorganic polymeric materials is predicted. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 179–191, 2002