bluuebunny/crossref_metadata_2025_split huggingface dataset:
Carbothermal synthesis of titanium nitride (TiN): Kinetics and mechanism
Authors: Ortega A. , Roldan M. A. , Real C. 
Published: July 2005

AbstractConstant rate thermal analysis (CRTA) has been used for studying the kinetics of the carbothermal reduction of anatase in nitrogen. It is noteworthy to point out the ability of CRTA method for discriminating the kinetic law of solid‐state reactions with considerably higher precision than conventional (TG, DTA, isothermal etc.) methods. The precise control of the reaction rate implies either direct or indirect control of both the partial pressure of CO generated in the reaction and the heat evolution rate, which allows to minimize the influence of heat and mass transfer phenomena.It has been shown that this synthesis is best described by a Johnson–Mehl–Avrami (with n = 2) kinetic model with an activation energy that fall in the range 162–165 kJ mol−1. Finally the results reported here constitute the first attempt to use the new CRTA method to study the kinetics of the carbothermal synthesis of TiN. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 566–571, 2005
Intramolecular reactions of free radicals formed from artemisinin
Authors: Denisov Evgeny , Denisova Taisa , Ismail Fyaz 
Published: July 2005

AbstractTwo cyclic alkoxyl radicals are formed as a result of peroxide bridge scission in artemisinin. Intramolecular reactions of these radicals induce the cascade of reactions of isomerization, decyclization, and decomposition of formed free radicals. It includes 14 reactions of intramolecular free radical hydrogen transfer, 17 reactions of decyclization of alkoxyl and alkyl radicals, and 4 reactions of decomposition of alkoxyl, acyl, and carboxyl radicals. The enthalpies of these 35 reactions are calculated. Using intersection parabolas method, activation energies and rate constants of all these reactions are calculated. The most rapid reactions are selected for every intermediate free radical. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 554–565, 2005
Dielectric Study of the Effect of a Sol‐Gel Inorganic Network on Polymeric Relaxation Dynamics in Acrylic/Titania Hybrids
Authors: Perrin François X. , Nguyen Van Nhan , Vernet Jean L. 
Published: July 2005

AbstractSummary: In this research, poly[(methyl methacrylate)‐co‐(butyl methacrylate)‐co‐(methacrylic acid)]/TiO2 hybrids were prepared by the sol‐gel process. The copolymer composition was 16 mol‐% methyl methacrylate (MMA), 80 mol‐% butyl methacrylate (BMA) and 4 mol‐% methacrylic acid (MA). The dielectric properties of the hybrids with varying titania content were measured over the frequency range 0.1 Hz to 100 kHz and between 25 and 160 °C. In addition, the hybrids were investigated using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). In the given frequency range, a single relaxation peak was observed both by dielectric relaxation spectroscopy (DRS) and DMTA. The single relaxation observed by DRS behaves in the manner of an α‐relaxation, with the frequency–temperature locus showing non‐Arrhenius behavior (curved downwards like a VTF law). The change in the DRS and DMTA characteristics in hybrids compared to the pure polymer reflect the presence of antagonistic mechanisms controlling the dynamics of the polymer chains: nanodomains with enhanced and restricted mobilities are suggested to be responsible for the broadening of the isochronal dielectric loss curve toward, respectively, the low and the high temperature sides. Combining the DSC and DRS results, it can be inferred that the domains with enhanced mobility result from internal and external plasticization effects that reduce the intermolecular hydrogen bonds between the polymer chains. Besides, the motion of polymer chains is found to be significantly hindered by the titania network, due to the presence of iono‐covalent bonds between the polymer and titania and geometrical restrictions in high junction‐point density and titania‐rich microphases. From the Arrhenius plot, it is also shown that the addition of sol‐gel titania more severely hinders the segmental motion of the macromolecular chains than the local motion of the lateral groups (β relaxation).Simplified schematic morphology for the poly(MMA‐co‐BMA‐co‐MA)/TiO2 hybrids.magnified imageSimplified schematic morphology for the poly(MMA‐co‐BMA‐co‐MA)/TiO2 hybrids.
DNA methylation in the CTCF‐binding site I and the expression pattern of the H19 gene: Does positive expression predict poor prognosis in early stage head and neck carcinomas?
Authors: Esteves Leda I.C.V. , Javaroni Afonso C. , Nishimoto Inês N. , Magrin José , Squire Jeremy A. , Kowalski Luiz P. , Rainho Cláudia A. , Rogatto Silvia R. 
Published: July 2005

AbstractLoss of allele‐specific expression by the imprinted genes IGF2 and H19 has been correlated with a differentially methylated region (DMR) upstream to the H19 gene. The H19‐DMR contains seven potential CCCTC‐binding factor (CTCF) binding sites. CTCF is a chromatin insulator and a multifunctional transcription factor whose binding to the H19‐DMR is suppressed by DNA methylation. Our study included a group of 41 head and neck squamous cell carcinoma (HNSCC) samples. The imprinting status of the H19 gene was analyzed in 11 out of 35 positive cases for H19 gene expression, and only 1 of them showed loss of imprinting. We detected a significant correlation (P = 0.041, Fisher's exact test) between H19 expression and tumor recurrence. Among H19 positive cases, six were T2, in which five developed recurrence and/or metastasis. Inversely, in the group of tumors that showed no H19 gene expression, 5 out of 24 were T2 and only 1 presented regional recurrence. These data support the hypothesis that H19 expression could be used as a prognostic marker to indicate recurrence in early stage tumors. We also examined the methylation of the CTCF binding site 1 in a subgroup of these samples. The H19 gene silencing and loss of imprinting were not correlated with the methylation pattern of the CTCF binding site 1. However, the significant correlation between H19 expression and tumor recurrence suggest that this transcript could be a marker for the progression of HNSCC. © 2005 Wiley‐Liss, Inc.
Thermal behavior and flame retardancy of flexible poly(vinyl chloride) treated with Al(OH)3 and ZnO
Authors: Qu Hongqiang , Wu Weihong , Jiao Yunhong , Xu Jianzhong 
Published: July 2005

AbstractAl(OH)3 as flame retardant and smoke suppressant for flexible poly(vinyl chloride) was evaluated alone and with ZnO, using thermal analytical techniques, limiting oxygen index and smoke density rating tests. The thermal behavior and flammability of the samples treated with Al(OH)3 and ZnO were studied by differential thermal analysis and thermogravimetric analysis. The activation energy was calculated by using the Vyazovkin model‐free kinetic and Kissinger methods. The results showed that the flame‐retardant and smoke‐suppressant properties of the samples treated with Al(OH)3 and ZnO were related to the content of ZnO and the thermal effect during the process of thermal degradation of the samples. Copyright © 2005 Society of Chemical Industry
The N‐terminal fragment of gelsolin inhibits the interaction of DNase I with isolated actin, but not with the cofilin‐actin complex
Authors: Chhabra Deepak , Nosworthy Neil J. , dos Remedios Cristobal G. 
Published: July 2005

AbstractApoptosis is essential in embryonic development, clonal selection of cells of the immune system and in the prevention of cancer. Apoptotic cells display characteristic changes in morphology that precede the eventual fragmentation of nuclear DNA resulting in cell death. Current evidence implicates DNase I as responsible for hydrolysis of DNA during apoptosis. In vivo, it is likely that cytoplasmic actin binds and inhibits the enzymatic activity and nuclear translocation of DNase I and that disruption of the actin–DNase I complex results in activation of DNase I. In this report we demonstrate that the N‐terminal fragment of gelsolin (N‐gelsolin) disrupts the actin–DNase I interaction. This provides a molecular mechanism for the role of the N‐gelsolin in regulating DNase I activity. We also show that cofilin stabilises the actin–DNase I complex by forming a ternary complex that prevents N‐gelsolin from releasing DNase I from actin. We suggest that both cofilin and gelsolin are essential in modulating the release of DNase I from actin.
Truncated cystatin C in cerebrospiral fluid: Technical artefact or biological process?
Authors: Carrette Odile , Burkhard Pierre R. , Hughes Severine , Hochstrasser Denis F. , Sanchez Jean‐Charles 
Published: July 2005

AbstractCystatin C, a low molecular weight cysteine proteinase inhibitor present in human body fluids at physiological concentrations, is more expressed in cerebrospinal fluid (CSF) than in plasma. Mass spectrometric characterization showed that after 3 months of storage of human CSF at −;20°C, cystatin C was cleaved in the peptide bond between R8 and L9 and lost its eight N‐termini amino acids, whereas this cleavage did not occur when stored at −80°C. This truncation occurred in all CSF samples studied irrespective of the underlying neurological status, indicating a storage‐related artefact rather than a physiological or pathological processing of the protein. These results stress the importance of optimal preanalytical storage conditions of any sample prior to proteomics studies.
Cryodetector mass spectrometry profiling of plasma samples for HELLP diagnosis: An exploratory study
Authors: Koy Cornelia , Heitner Juliane C. , Woisch Ralf , Kreutzer Michael , Serrano‐Fernandez Pablo , Gohlke Rüdiger , Reimer Toralf , Glocker Michael O. 
Published: July 2005

AbstractThe cryodetector MS‐based screening method enables the rapid and reliable separation of hemolysis, elevated liver enzymes, and low platelets syndrome (HELLP) patients from healthy women. For developing the assay, plasma protein abundances from patients suffering from HELLP were profiled before and after delivery and compared to healthy pregnant and nonpregnant control individuals, using a TOF mass spectrometer equipped with a cryodetector system. The spectra were well reproducible when acquisition conditions were kept constant and the overall appearance of the profiles was well comparable. Peak areas of ten selected ion signals (9.5, 11.8, 14.0, 28.1, 43.4, 50.5, 60.1, 66.6, 74.5, and 79.8 kDa) from each spectrum were subjected to statistical analysis. Significant differences in ion intensities between the groups could be measured even without sample fractionation. The most striking difference between most of the spectra from HELLP patients and nonHELLP samples was the presence/absence of the 11.8 kDa ion signal (p‐value: 0.0000365), most likely belonging to serum amyloid A (SAA). Other significant differences in ion intensities between HELLP and control samples were observed in the peak areas of the 14.0, 28.1, 50.5, and 74.5 kDa ion signals. Using the cryodetector MS data for sorting plasma samples into either the HELLP group (n = 8) or the nonHELLP group (n = 22), a sensitivity of 87.5% and a specificity of 100% were achieved. The positive predictive value of our screening assay was 100% and a negative predictive value of 95.6% was obtained with the samples included in this study.
Polymeric and colloidal features of latex particles with surface amino groups obtained by semicontinuous seeded cationic emulsion polymerization*
Authors: Ramos Jose , Forcada Jacqueline 
Published: July 2005

AbstractMonodisperse latex particles with different amounts of surface amino and amidine groups were synthesized by means of a semicontinuous seeded cationic emulsion polymerization of styrene and a cationic monomer. High partial overall conversions for styrene and limited ones for the cationic monomer were achieved. A reliable method for the quantification of surface amidine and amino groups was developed. It was found that the amount of surface amidine groups provided by the cationic initiator was higher when the amount of cationic monomer added increased. The value for the partition coefficient of the cationic monomer indicated that this polymerizes with the same probability in the water phase as in the particle. The colloidal stability, in terms of critical coagulation concentration, shows that the latexes would be useful as polymeric supports in immunoassays. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3878–3886, 2005
Synthesis of high molecular weight polystyrene and poly(methyl methacrylate) with low polydispersity by [Cp2ZrCl2] catalyzed aqueous polymerization
Authors: Patra Braja N. , Bhattacharjee Manish 
Published: July 2005

AbstractAn early transition metal metallocene compound, Cp2ZrCl2, with an anionic surfactant, sodium n‐dodecyl sulfate (SDS) as emulsifier has been found to be an effective catalyst for polymerization of monomers like styrene and methylmethacrylate in aqueous medium. The molecular weights of the polymers have been found to be very high with low molecular weight distribution. The added surfactant has been found to play the dual role of stabilizer of the cation as well as an emulsifying agent for the monomer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3797–3803, 2005
Dendronized polymers with tailored surface groups
Authors: Nyström Andreas , Hult Anders 
Published: July 2005

AbstractA series of polymers tethered with bis‐MPA dendrons was synthesized by a combination of divergent growth and atom transfer radical polymerization (ATRP). Macromonomers of first and second generation were synthesized utilizing the acetonide protected anhydride of bis‐MPA as the generic esterfication agent. The macromonomers were polymerized in a controlled fashion by ATRP utilizing Cu(I)/Cu(II) and N‐propyl‐2‐pyridylmethanamine as the halogen/ligand system. The end‐groups of these polymers were further tailored to achieve hydroxyl, acetate, and aliphatic hexadecyl functionality. With this approach all polymers will emanate from the same backbone, enabling for an evaluation of both the generation and end‐group dependent properties. Furthermore, a dendronized tri‐block copolymer was synthesized. All materials were analyzed by 1H and 13C NMR, as well as size‐exclusion chromatography (SEC). The SEC analysis revealed that the molecular weights of the divergently grown dendronized polymers increased with increasing generation while the polydispersity (PDI) was kept low. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3852–3867, 2005
Synthesis of carbohydrate‐segmented polydimethylsiloxanes by hydrosilylation
Authors: Henkensmeier Dirk , Abele Bors Cajus , Candussio Anton , Thiem Joachim 
Published: July 2005

AbstractCarbohydrate‐modified polysiloxanes have been presented several times within the last decade. In this work, a new route to carbohydrate‐segmented polysiloxanes is presented. A series of allyl‐group‐containing bifunctional carbohydrate derivatives was synthesized and reacted with hydrodimethylsilyl‐terminated polysiloxane in hydrosilylation reactions with Speier's catalyst. The carbohydrate monomers and the resulting materials were fully characterized with 1H and 13C NMR spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3814–3822, 2005
Unconstrained geometry complexes: Ethylene/α‐olefin copolymerizations with a tetramethyldisilyl‐bridged Cp‐amido titanium complex
Authors: Hung Joyce , Waymouth Robert M. 
Published: July 2005

AbstractA new disilyl‐bridged complex, [(N‐tert‐butylamido)(3‐indenyl)tetramethyldisilyl]titanium dichloride (3), was synthesized and activated with methylaluminoxane (MAO) for propylene homopolymerization and ethylene/propylene and ethylene/1‐hexene copolymerizations. A polypropylene with a slight isotactic enrichment was obtained. The number of regioerrors present in the polypropylene was somewhat smaller than that found in most polypropylenes made from monosilyl‐bridged [(N‐tert‐butylamido)(3‐indenyl)dimethylsilyl]titanium dichloride. The regioerrors detected in the copolymers obtained from 3/MAO were on the order of the amounts observed in polymers made with the monosilyl‐bridged constrained geometry catalysts. Ethylene copolymers of propylene and 1‐hexene had random sequence distributions and showed significant comonomer incorporation. Because of the presence of regioerrors, a modified method for determining the monomer composition and sequence distribution was developed from the direct measurement of the monomer content from the number of methylene and methine carbons per polymer chain, regardless of propylene inversion. An estimate of the error in the copolymerization reactivity ratio determination for regioirregular ethylene/α‐olefin copolymers was obtained by the calculation of the reactivity ratios from monomer dyad sequences, with consideration given to the contribution of major regioirregular sequences. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3840–3851, 2005
Systematic parallel investigation of RAFT polymerizations for eight different (meth)acrylates: A basis for the designed synthesis of block and random copolymers
Authors: Fijten Martin W. M. , Paulus Renzo M. , Schubert Ulrich S. 
Published: July 2005

AbstractPoly(acrylate)s as well as poly(methacrylate)s were successfully synthesized via reversible addition‐fragmentation chain‐transfer (RAFT) polymerizations using 2‐cyano‐2‐butyl dithiobenzoate (CBDB) as RAFT‐agent. Four different ratios of RAFT to initiator were screened for four acrylates and four methacrylates using automated parallel synthesizer robots. The reactions were monitored by gel permeation chromatography (GPC) and gas chromatography (GC). The knowledge obtained during this screening was used for the designed synthesis of block and random copolymers containing a water‐ and a non water‐soluble monomer. The results obtained from GPC analysis together with 1H NMR spectroscopy demonstrate the possibility to design and prepare well‐defined block and random copolymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3831–3839, 2005
Isothermal and nonisothermal crystallization kinetics of irradiated nylon 1212
Authors: Song Jianbin , Ren Minqiao , Chen Qingyong , Sun Xiaohong , Zhang Huiliang , Song Chunlei , Zhang Hongfang , Mo Zhishen 
Published: July 2005

AbstractThe crystallization behavior of nylon 1212, irradiated at 60Co γ‐rays (50 kGy), was studied by a rheometer, polarized optical microscopy (POM), and differential scanning calorimeter (DSC). The results showed that irradiated nylon 1212 samples exhibited abnormal crystallization behavior during the crystallization process: The Avrami exponent n was calculated and was found to be in the range from 2.06–2.41 for isothermal crystallization, and from 2.67–4.91 for nonisothermal crystallization; the spherulite morphology also changed largely by polarized optical microscopy (POM); the crystallization activation energy ΔE for isothermal and nonisothermal crystallization process of irradiated nylon 1212 are determined to be 57.4 kJ/mol and 78.65 kJ/mol, respectively, which are lower than that of nonirradiated nylon 1212. At the same time, a new method by a combination of the Avrami and Ozawa equations was successfully applied to analyze the noncrystallization process of irradiated nylon 1212. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2326–2333, 2005
Thermoplastic blend demixing by a high‐pressure, high‐temperature process
Authors: Barbosa Silvia , Diaz Mónica , Mabe Guillermo , Brignole Esteban A. , Capiati Numa 
Published: July 2005

AbstractThe analysis of a thermoplastic polymer blend requires a precise separation of the blend components, which is usually performed by selective solvent extraction. However, when the components are high‐molecular‐weight polymers, a complete separation is very difficult. The use of fluids in near critical and supercritical conditions becomes a promising alternative to reach a much more precise separation. In this work, a method to separate reactive and physical blends from high‐molecular‐weight commercial polymers is proposed. Polyethylene (PE)/polystyrene (PS) blends were separated into their components with n‐propane, n‐pentane, and n‐heptane at near critical and supercritical conditions. The selectivity of each solvent was experimentally studied over a wide range of temperatures for assessing the processing windows for the separation of pure components. The entire PE phase was solubilized by n‐pentane and n‐heptane at similar temperatures, whereas propane at supercritical conditions could not dissolve the fraction of high‐molecular‐weight PE. The influence of the blend morphology and composition on the efficiency of the polymer separation was studied. In reactive blends, the in situ copolymer formed was solubilized with the PE phase by chemical affinity. The method proposed for blend separation is easy, rapid, and selective and seems to be a promising tool for blend separation, particularly for reactive blends, for which the isolation of the copolymer is essential for characterization © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2361–2369, 2005
Modification of the structure and properties of poly(vinylidene fluoride–trifluoroethylene) 56/44 mol % copolymer by a proton‐irradiation treatment
Authors: Lam T. Y. , Lau S. T. , Chan H. L. W. , Choy C. L. , Cheung W. Y. , Wong S. P. 
Published: July 2005

AbstractThe effects of high‐energy proton irradiation on the structure and properties of 56/44 mol % poly(vinylidene fluoride–trifluoroethylene) copolymer were studied with differential scanning calorimetry (DSC), X‐ray diffraction (XRD), relative permittivity, and polarization hysteresis measurements. Copolymer films prepared by hot compression molding were irradiated with a broad range of proton dosages (10–107 Mrad) at room temperature. The DSC results showed that the ferroelectric transition was strongly affected by the proton dosages. The XRD data indicated the reduction of polar ordering in the copolymer by the proton‐irradiation treatment. From the relative permittivity and polarization behavior, the copolymer film was found to be converted from a normal ferroelectric material to a relaxor ferroelectric material as the proton dosage was increased to 50 Mrad. The electrostrictive coefficient of the 56/44 mol % copolymer was enhanced after irradiation, and the optimized proton dosage for attaining the highest electrostrictive strain response was determined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2334–2339, 2005
Intussusceptions arising from two different sites in a child with cystic fibrosis
Authors: Hafen Gaudenz M. , Taylor Andrew C. , Oliver Mark R. , Stokes Keith B. , Rao Padma , Robertson Colin F. , Ranganathan Sarath C. 
Published: July 2005

AbstractAbdominal pain is common in individuals with cystic fibrosis (CF). We report on a 17‐year old boy with CF and two recognized intussusceptions: the first colonic intussusception was presumed due to distal intestinal obstruction syndrome, and the second enteric one due to polypoid lesions containing heterotopic gastric mucosa. The presentation, pathology, management, and a literature review of intussusception in CF are discussed. Pediatr Pulmonol. © 2005 Wiley‐Liss, Inc.