bluuebunny/crossref_metadata_2025_split huggingface dataset:
The action of heat on the polyorganosiloxanes derived from the minerals biotite and pseudowollastonite by trimethylsilylation
Authors: Cook Colin B. , Currell Brian R. , Midgley Henry G. , Parsonage John R. , Thakur Chandra P. 
Published: April 2007

AbstractThe polyorganosiloxanes prepared by the trimethylsilylation of mineral silicates contain Q [SiO4/2] units and M [CH3)3 SiO1/2] units. Investigations into the behaviour of these materials in the temperature range 100‐1000°C and for times varying from 2‐64 hours have shown that a variety of reactions take place with a general increase in number average molecular weight (Mn). Organophilic polyorganosiloxanes with Mn > 6000 can be obtained by heat treatment under vacuum or a stream of nitrogen. The thermal stability of the polymer derived from pseudowollastonite in closed systems in the presence of acid/base catalysts is also reported. This work is part of a general programme to prepare higher molecular weight Q/M polymers with more potential uses as industrial materials than the initially prepared trimethylsilylated derivatives.
Some reactions of the methyl groups of the trimethylsilyl derivative of the mineral pseudowollastonite
Authors: Cook Colin B. , Currell Brian R. , Midgley Henry G. , Parsonage John R. 
Published: April 2007

AbstractThe trimethylsilylation of pseudowollastonite gives a polyorganosiloxane (Mn, 890). The aim of this work was to increase the molecular weight of this initial or pre‐polymer and to bond into the molecule further functional groups. The methyl groups of the trimethylsilyl moiety have been converted to a series of organic derivatives: ‐> Si(CH3)2CH2X; × = C1, Br, I, Ac, OH: which are capable of further reaction to give higher molecular weight homologues. As expected the ‐>Si(CH3)2CH2OH group reacts readily with chlorosilancs whilst the original pre‐polymer hydroxyl groups give disappointing yields in these and other reactions owing to their sterically hindered environment.
Mechanical properties of globular protein gels: II concentration, pH concentration, ph and ionic strength dependence
Authors: Richardson Robert K. , Ross‐Murphy Simon B. 
Published: April 2007

AbstractAqueous gels can be made by heating concentrated solutions of the globular protein BSA above its unfolding temperature, around 60°. The effect of such factors as length of heating, protein concentration, pH and ionic strength on the small deformation shear modulus of the gel is determined. The results may be rationalised qualitatively in terms of the effect of these factors on the homogeneity and of the microstructure of the gel, but a quantitative description of the rheological properties in such a complex system remains to be found.
Effects of calcium carbonate fillers on the behaviour of PVC in fires
Authors: Matthews George , Plemper George S. 
Published: April 2007

AbstractThe effects of particle size and concentration of calcium carbonate fillers on the critical oxygen index and the evolution of hydrogen chloride during pyrolysis of PVC have been examined. Both retention of hydrogen chloride in the condensed phase and critical oxygen index chloride in the condensed phase and critical oxygen index depend not only on concentration but also on particle size of the calcium carbonate. Efficiency of retention of hydrogen chloride increases with decreasing particle size and approaches 100% at particle sizes below 0.1 micron. Critical oxygen index is not appreciably affected by calcium carbonates of particle size around one micron. Coarser calcium carbonates increase critical oxygen index, while finer calcium carbonates decrease it up to concentrations at which all the hydrogen chloride is retained in the condensed phase, after which it is steadily increased with increasing concentration.
General expressions of average molecular weights in polycondensation of polyfunctional monomers involving condensation by‐product
Authors: Durand Dominique , Bruneau Claude‐Marcel 
Published: April 2007

AbstractIn this paper, the general expressions of average molecular weights for condensation polymerisation involving eliminat species are derived in the pre‐gel region especially for systems composed of monomers endowed with both A and B coreactive functional groups. The weight average molecular weights are calculated directly according to a new method using the propagation expectation.
Thermodynamic and rheological properties of rodlike polymers
Authors: Berry Guy C. , Cotts P. Metzger , Chu Sung‐Gun 
Published: April 2007

AbstractInvestigations on dilute and concentrated solutions of several rodlike polymers are described. The former includes absolute and intensity fluctuation light scattering, exclusion chromatography and viscometry. The latter includes rheological properties of isotropic and anisotropic solutions. The discussion includes data for four rodlike polymers, each soluble only in strong sulphonic acids. The role of electrostic interactions and molecular association on the properties measured is considered. The similarities and differences of the rheological behaviour with that typically found with flexible chain polymers are pointed out.
Rapid polymerisation and cross‐linking reactions in thin film (1) the stopped‐flow rotational viscometer: Construction and preliminary studies
Authors: Sutton Geoffrey J. , Tighe Brian J. 
Published: April 2007

AbstractThe design and construction of a stopped flow rotational viscometer is described. This novel technique enables rapid polymerisation reactions in thin films to be studied in a controlled environment over a range of temperatures. The apparatus enables two components of a polymerisation system (typically monomer/solvent and initiator/solvent) to be separately and rapidly delivered to the sample cavity of a cone and plate viscometer. The flow of the components can be simultaneously arrested and the viscosity of the resultant monomer/initiator/solvent mixture monitored as a function of time. The system was designed for the study of cyclo olefin‐based polymerisation and cross‐linking reactions in the development of metal coating systems capable of high cross‐linking rates. An initial evaluation was however carried out using the well characterised free radical polymerisation of styrene and the cationic polymerisation of styrene catalysed by boron trifluoride etherate in toluene.
Thermal modification of amine cured epoxy resins ‐ thermal and mechanical studies
Authors: Maxwell Ian D. , Pethrick Richard A. , Datta Prasanta K. 
Published: April 2007

AbstractMechanical test data are reported on lap joints and tensile test specimens which have been subjected to a defined post cure cycle. The mechanical properties exhibited an apparently systematic variation with temperature. Inspection of the resins indicated that chemical modification does not appear to occur to a significant extent below 433K. The change in the strength of the joints tensile test samples are discussed in terms of the relative importance of physical and chemical changes on the mechanical properties. It is evident that in the presence of oxygen considerable chemical modification can occur and this is observed both in terms of a change in colour of the resin and the appearance of voids.
Preparation of ionic polyphosphonasiloxanes
Authors: Collis Anthony J. , Currell Brian R. , Grzeskowiak Roman , Lynn Michael E. 
Published: April 2007

AbstractMixtures of polyphosphonasiloxane oligomers have been prepared by the interaction of Ph2SiCl2 with PhPO(OH)2 and of Me2SiCl2 with MePO(OH)2. Substitution of LiH2PO4 for PhPO(OH)2 and MePO(OH)2 leads to the formation of polyphosphonasiloxanes containing ‐ O−Li+ groups. The Tg's of these products increase as greater amounts of lithium phosphate are incorporated. Use of NaH2PO4 does not produce polymers containing ‐ O−Na+, instead reaction of the ‐O−Na+ groups with Si‐Cl leads to the elimination of NaCl and the formation of cross‐linked polymers.
Preparation of overcoated polymer latices by a ‘shot growth’ technique
Authors: Chainey Malcolm , Hearn John , Wilkinson Michael C. 
Published: April 2007

AbstractA ‘shot growth’ technique has been developed which enables a monodisperse polymer latex to be overcoated with a range of coating thicknesses by a different polymer. This has enabled a range of polymer latices to be produced which have mechanical and diffusional characteristics which are very different from either the seed latex or the coating polymer.
Phase equilibria in the two‐phase system polystyrene—liquid sulphur dioxide
Authors: Albihn Per , Kubát Josef 
Published: April 2007

AbstractThe concentration and molecular weight distribution (GPC) of polystyrene (PS) in the two phases of the PS‐SO2 (δ)‐system were determined. Typical concentrations of PS in the upper phase were around 30%, while the lower phase contained at most 1% PS. An exception was a PS‐grade with a low molecular weight (MW 3.5 · 103), which dissolved homogeneously. The molecular weight of PS in the lower phase was substantially below an the one found in the concentrated phase. Mechanical agitation was necessary to attain an equilibrium state; during the equilibration the upper phase became more diluted. At the same time the molecular weight of the lower phase PS‐fraction increased, while the MW value in the upper phase remained practically unchanged and equal to that of the virgin sample. The fractionation with regard to the molecular weight between the two phases was also reflected in the Tg‐values of the fractions. The value of X(Flory‐Huggins parameter) determined from vapour pressure data above the concentrated phase was 0.8–1.
The complete analysis of the polyorganosiloxanes formed by the trimethylsilylation of the minerals olivine and suzorite
Authors: Currell Brian R. , Midgley Henry G. , Parsonage John R. , Soubhi Suleyman , Vidgeon Edward A. 
Published: April 2007

AbstractMethods are reported for the separation and complete quantitative estimation of the polyorganosiloxanes prepared by the trimethylsilylation of mineral silicates. Quantitative methods for the determination of low molecular weight oligomers up to Q6M12 (Q≡SiO4/2; M≡(CH3)3SiO1/2) are well known but there are no previously reported methods for the determination of high molecular weight species. This paper describes the application of gel permeation chromatography and quantitative high performance liquid chromatography to the study of these higher molecular weight species. Polyorganosiloxanes prepared from suzorite (a phlogopite) and from olivine (an orthosilicate) are used as examples. A further example is a study of the formation of higher molecular weight species on heating these polymers.
Thermally stimulated discharge current studies in copper phthalocyanine ‐ doped polystyrene films
Authors: Shrivastava S. K. , Ranade J. D. , Shrivastava A. P. 
Published: April 2007

AbstractTo improve the electret characteristics, TSD current studies of copper phthalocyanine ‐ doped polystyrene films of about 20 microns thickness have been made as a function of doping concentration, poling temperature and field. Generally the thermograms observed exhibit α and ρ peaks. The activation energy is found to decrease as the concentration of the dopant in the polymer is increased. It is established that keeping the forming field constant and by increasing the concentration of the dopant, the same polarisation can be obtained at a lower poling temperature. A Maxwell‐Wagner two‐phase model with space ‐ charge build‐up seems to provide a possible mechanism for the polarisation.
Photo‐polarisation in pure and doped polystyrene
Authors: Shrivastava S. K. , Ranade J. D. , Srivastava A. P. 
Published: April 2007

AbstractDepolarisation currents have been measured of the photo‐electrets of pure and copperphthalocyanine doped polystyrene films using UV‐radiation. A hyperbolic decay law is observed suggesting bimolecular recombination process. Doped films show strong saturation with the applied field supporting a trap filling mechanism.
The electropolymerisation of acrylamide on carbon fibres
Authors: MacCallum James R. , MacKerron Duncan H. 
Published: April 2007

AbstractPolyacrylamide has been synthesised at the surface of carbon fibre by the technique of electropolymerisation. Some details of the polymerisation have been presented and a preliminary proposal made for the mechanism responsible. The characterisations of carbon fibre and its surface have always presented a problem; in this work torsional braid analysis has been used to study the polymer present on the surface of the fibre.
The use of 29Si fourier transform nuclear magnetic resonance spectroscopy for the characterisation of polymers and paints
Authors: Marshall Gregory L. 
Published: April 2007

AbstractA range of commercial paint binders and two‐pack elastomers containing silícone materials have been investigated by 29Si Fourier transform nuclear magnetic resonance spectrocopy at 17.76MHz. In order to obtain good quality spectra within a minimum of time period, a relaxation agent was used to supress nuclear Overhauser effects, and to improve the relaxation times of the silicon nuclei.
Upper and lower critical solution temperatures in 2‐butanone solutions of cellulose diacetate
Authors: Suzuki H. , Muraoka Y. , Saitoh M. , Kamide K. 
Published: April 2007

AbstractIt was found that cellulose diacetate (the degree of substitution = 2.46) dissolved in 2‐butanone but that these solutions presented cloud points in both regions of the lower and upper critical solution temperatures (LCST and UCST). The cloud points were measured for one unfractionated and three well‐fractionated samples, from which the LCST and UCST were determined. The CST data were plotted according to Shultz and Flory, to yield the results of θu = 310K and θL = 433K. Here, θ is the theta point and the subscripts U and L refer to the UCST and LCST respectively. The present CST data were first compared with the prediction of a corresponding states theory by Patterson. When the Cowie‐McEwen semi‐empirical rule was employed to estimate the solvent characteristic temperature, a quantative agreement with the observed LCSTs was obtained, while the predicted USTs were too low in comparison with the observed ones. Secondly, an analysis according to Eichinger's theory offered information showing that the thermodynamic parameters of the present system were less temperature dependent. Differences between the present and the ordinary systems to which the Cowie‐McEwen method was applicable were enumerated, each of the being examined from several points of view. A consideration that the 2‐butanone molecules were solvated onto the cellulose diacetate molecules was helpful to explain the solubility behaviour of the present polymer.
Study on Mixed Glycols‐based Semi‐flexible Unsaturated Polyester Resins for Inhibition of Rocket Propellants
Authors: Agrawal J. P. , Chowk M. P. , Satpute R. S. 
Published: April 2007

AbstractSeven semiflexible unsaturated polyester resins based on isophthalic acid, maleic anhydride and polyethylene glycol‐200 and propylene glycol (in different proportions) have been synthesised and characterised for gel time, exotherm peak temperature, tensile strength, percentage elongation, bond strength, nitroglycerine absorption, water absorption, flame resistance and voltile losses. The effect of glycol variation on these properties has also been discussed. Based on the data for various characteristics, resin 4 has been selected for inhibition and static evaluation of propellant. The propellant sustainers containing 2 NDPA have been inhibited with resin 4 without the application of any barrier coats and statically fired at ambient, cold and hot temperatures. The results of the static firings prove the worthiness of the new direct bonding inhibition system.
Surface photovoltaic effect in CdTe as influenced by recombination in the space‐charge region
Authors: Toušek J. , Toušková J. , Belas E. , Votoček L. 
Published: April 2007

AbstractDiffusion length of minority carriers in CdTe wafers was measured by the surface photovoltage (SPV) method. A model including recombination in the space‐charge region (SCR) is presented to explain the SPV spectra. Assuming a thick neutral bulk and an electric field only in the SCR, five parameters are needed for characterization of the system. On analyzing the problem we have found that the most important of them – the diffusion length of minority carriers L – is not influenced by recombination in the SCR. The results are verified on samples with different resistivities, and extracted diffusion length is compared with literature data. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of growth defects in thin GaN layers with X‐ray microbeam
Authors: Barabash R. I. , Ice G. E. , Roder C. , Budai J. , Liu W. , Figge S. , Einfeldt S. , Hommel D. , Davis R. F. 
Published: April 2007

AbstractThe spatially resolved distribution of strain, misfit and threading dislocations, and crystallographic orientation in uncoalesced GaN layers grown on Si(111) by maskless cantilever epitaxy or by pendeo epitaxy on SiC was studied by white beam Laue X‐ray microdiffraction, scanning electron and orientation imaging microscopy. Tilt boundaries formed at the column/wing interface depending on the growth conditions. A depth dependent deviatoric strain gradient is found in the GaN. The density of misfit dislocations as well as their arrangement within different dislocation arrays was quantified. Two different kinds of tilt (parallel and perpendicular to the stripe direction) manifested themselves by mutually orthogonal displacements of the (0006) GaN Laue spot relative to the Si(444) Laue spot. The origin of the tilts is discussed with respect to the miscut of the Si(111) surface and misfit dislocations formed at the interface. Regular oscillations of the conventional wing tilt were observed. Irregular crystallographic tilts fluctuations were found in the direction parallel to stripes. The amplitude of fluctuations is an order of magnitude smaller for layers with a lower defects density. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of ethanol extracts from Adzuki bean (Phaseolus angularis Wight.) and Lima bean (Phaseolus lunatus L.) on estrogen and progesterone receptor phenotypes of MCF‐7/BOS cells
Authors: Zhao Qing‐wei , Huang Xin , Lou Yi‐jia , Weber Nadine , Proksch Peter 
Published: April 2007

AbstractIn this study, the possible molecular mechanisms involved in the estrogen‐like activities of ethanol extracts from two common Chinese legumes, i.e. Adzuki bean (Phaseolus angularis Wight.) and Lima bean (Phaseolus lunatus L.) were investigated. Reverse transcription‐polymerase chain reaction (RT‐PCR) measurement and western blot analysis were conducted to detect the functional mRNA and protein expressions, while immunofluorescence was used to determine the estrogen receptor (ER) intracellular distribution in the MCF‐7/BOS cell line. The results indicated that (1) both mRNA and protein levels of progesterone receptor (PR) in the cell line increased after 48 h treatment with the extracts compared with those in the control; (2) Adzuki and Lima bean extracts might alter the ER intracellular distributions in two different manners: for the Adzuki bean, the ER appeared in both cytoplasm and nucleus, while for the Lima bean, it exhibited the same pattern as that of estradiol in which the ER almost disappeared in the nucleus and mainly occurred in the cytoplasm. Above all, the results showed a novel pattern of ER intracellular distribution in the MCF‐7/BOS cell line upon exposure to Adzuki bean extract, suggesting that different pathways were involved in the estrogen‐like activities of the ethanol extracts of Adzuki bean and Lima bean. Copyright © 2007 John Wiley & Sons, Ltd.
Phytochemical, pharmacological and ethnobotanical studies in mango ginger (Curcuma amada Roxb.; Zingiberaceae)
Authors: Jatoi Shakeel Ahmad , Kikuchi Akira , Gilani Syed Abdullah , Watanabe Kazuo N. 
Published: April 2007

AbstractCurcuma amada Roxb. is an important species known as mango ginger due to its characteristic raw‐mango aroma. It has a long history of traditional uses ranging from folk medicine to several culinary preparations. The phytochemical, pharmacological and ethnobotanical studies of C. amada are reviewed. The rhizome is rich in essential oils, and more than 130 chemical constituents with biomedical significance have been isolated from it. Its antibacterial, insecticidal, antifungal and antioxidant properties have been investigated. The conservation of indigenous knowledge by proper documentation is suggested. The chemotaxonomy, allelopathy and genetic diversity of C. amada have not yet been explored, and many such studies are possible. This review was compiled to provide consolidated information covering different aspects of the plant, to provide a basis on which to plan future studies and to promote sustainable use of C. amada. Copyright © 2007 John Wiley & Sons, Ltd.
Local structures in Pb1−xMnxTe systems
Authors: Radisavljević I. , Ivanović N. , Novaković N. , Romčević N. , Mitrić M. , Andrić V. , Mahnke H.‐E. 
Published: April 2007

AbstractThe semimagnetic semiconductor Pb1−xMnxTe is a good representative of IV‐VI narrow‐gap semiconductors, the class of materials in which phenomena like variation of the band gap with composition, negative magnetoresistance, long‐term non‐equilibrium processes, and the phonon dispersion anomalies, have been readily observed. The off‐centering effects (i.e. displacement of the atoms from the regular lattice positions), and related low temperature ferroelectric phase transition, are also characteristic of these systems. In the attempt to resolve exact positions of both constitutive and impurity atoms, possibilities and features of their ordering and (or) clustering, and configurational and thermal disorder in the systems, we have performed EXAFS measurements at DESY‐HASYLAB X1 and A1 beam lines, on Te and Mn absorption K‐edges, for samples with different Mn concentrations (x = 0.002, 0.02, 0.1) at room temperature and 10 K. The results reveal that these systems are intrinsically quite disordered. The most significant deviations of the local structure from that predicted by X‐ray diffraction measurements are found around Mn atoms, and increase with Mn concentration. Copyright © 2007 John Wiley & Sons, Ltd.
Dosage rescue by UBC4 restores cell wall integrity in Saccharomyces cerevisiae lacking the myosin type II gene MYO1
Authors: Díaz‐Blanco Nitza L. , Rodríguez‐Medina José R. 
Published: April 2007

AbstractMyosin II is important for normal cytokinesis and cell wall maintenance in yeast cells. Myosin II‐deficient (myo1) strains of the budding yeast Saccharomyces cerevisiae are hypersensitive to nikkomycin Z (NZ), a competitive inhibitor of chitin synthase III (Chs3p), a phenotype that is consistent with compromised cell wall integrity in this mutant. To explain this observation, we hypothesized that the absence of myosin type II will alter the normal levels of proteins that regulate cell wall integrity and that this deficiency can be overcome by the overexpression of their corresponding genes. We further hypothesized that such genes would restore normal (wild‐type) NZ resistance. A haploid myo1 strain was transformed with a yeast pRS316‐GAL1‐cDNA expression library and the cells were positively selected with an inhibitory dose of NZ. We found that high expression of the ubiquitin‐conjugating protein cDNA, UBC4, restores NZ resistance to myo1 cells. Downregulation of the cell wall stress pathway and changes in cell wall properties in these cells suggested that changes in cell wall architecture were induced by overexpression of UBC4. UBC4‐dependent resistance to NZ in myo1 cells was not prevented by the proteasome inhibitor clasto‐lactacystin‐β‐lactone and required the expression of the vacuolar protein sorting gene VPS4, suggesting that rescue of cell wall integrity involves sorting of ubiquitinated proteins to the PVC/LE–vacuole pathway. These results point to Ubc4p as an important enzyme in the process of cell wall remodelling in myo1 cells. Copyright © 2007 John Wiley & Sons, Ltd.