bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of Highly Soluble Poly(aryl ether ketone‐benzoxazole) Copolymers with Hexafluoroisopropylidene Moieties by Direct Copolymerization
Authors: Li Jinhuan , Lee Young Moo 
Published: October 2006

AbstractSummary: A series of new poly(aryl ether ketone‐benzoxazole)s (PAEKBOs) with hexafluoroisopropylidene moieties were synthesized directly by the aromatic nucleophilic polycondensation of 2,2′‐bi[2‐(4‐fluorophenyl)benzoxazol‐6‐yl]hexafluoropropane(6F‐BO), 4,4′‐difluorobenzophenone (DFBP) and 4,4′‐(hexafluoroisopropylidene)diphenol (6F‐OH) at various molar ratios. High molecular weight polymers with both benzoxazole and ether‐ketone units were readily obtained. The copolymers with >20 mol‐% content of ether‐ketone units were highly soluble in organic solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), m‐cresol, tetrahydrofuran (THF) and CHCl3. The thermal stability of PAEKBOs was not significantly compromised compared with the relevant homopolymer compositions, hexafluoroisopropylidene containing poly(aryl ether ketone) (6F‐PAEK) without benzoxazole units and hexafluoroisopropylidene containing poly(ether benzoxazole) (6F‐PEBO) without ether‐ketone units. A 5% weight loss of the copolymers occurred at above 440 °C in air and above 480 °C in N2. Single glass transition temperatures (Tgs) were observed and ranged from 182 to 228 °C depending on the composition of the copolymers. The PAEKBO copolymers were essentially in the amorphous state, as determined using DSC, WAXD and DMA. For polymer films with a thickness of 30–80 µm, moduli between 1 700 and 2 100 MPa and strengths between 40 and 90 MPa were achieved. The PAEKBO copolymers behaved in many respects as engineering thermoplastics and could be processed from solution and the melt.Structure of PAEKBO.magnified imageStructure of PAEKBO.
Synthesis and Characterization of Functionalized Crosslinkable Poly(ε‐caprolactone)
Authors: Laurienzo Paola , Malinconico Mario , Mattia Giuditta , Romano Gennaro 
Published: October 2006

AbstractSummary: A new and rather simple method to obtain randomly crosslinked PCL is reported. PCL was previously functionalized through radical grafting of MA and GMA in the melt, using a Brabender‐like apparatus. GMA was added in order to obtain higher grafting efficiency. The structure of PCL‐g‐MAGMA was elucidated by 1H NMR spectroscopy, and the content of grafted MA was determined by FT‐IR spectroscopy. PCL‐g‐MAGMA was successively crosslinked through reaction with HMDI. The degree of crosslinking was determined by solvent extractions with chloroform. Thermal and dynamic mechanical analysis and tensile tests were performed on plain PCL, on PCL‐g‐MAGMA and on crosslinked PCL samples.Schematic representation of PCL‐g‐MAGMA structure.magnified imageSchematic representation of PCL‐g‐MAGMA structure.
Self‐Assembled Structures in Blends of Block Copolymer A‐block‐B with Homopolymer A: SAXS and SANS Study
Authors: Holoubek Jaroslav , Baldrian Josef , Lednický František , Málková Šárka , Lal Jyotsana 
Published: October 2006

AbstractSummary: The study describes the investigation of the microphase‐separated morphology of a block copolymer A‐block‐B with the parent homopolymer A, where A is polystyrene and A‐block‐B is poly(perdeuterated styrene)‐block‐poly(methyl methacrylate) (dPS‐block‐PMMA). The microdomain morphology and phase behavior in blends of dPS‐block‐PMMA with polystyrene of $\overline M _{\rm w}$ = 8 000 and 35 000 were investigated. Binary blends of the diblock copolymer and homopolymers were prepared with various amounts of homopolymers. The criterion for “wet and dry brush” taking into account different solubilization of homopolymer has been applied to explain the changes in microdomain morphology during the self‐assembling process.
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NMR Study of Hyperbranched Polyphenylenes from the AB2, (AB2 + AB) and (A2 + B3) Methods
Authors: Komber Hartmut , Stumpe Katrin , Voit Brigitte 
Published: October 2006

AbstractSummary: The 1H NMR and 13C NMR spectra of hyperbranched polyphenylenes synthesised from AB2, (AB2 + AB) and (A2 + B3) monomers (A: ethynyl group; B: cyclopentadienonyl group) were analysed with respect to the characteristic substructures of these polymers. The broad and overlapping NMR spectra were studied by a combination of 1D and 2D NMR techniques. Furthermore, appropriate model compounds were synthesised, and their 1H and 13C NMR spectra were fully assigned. The signal assignments achieved allow to substantiate the different hyperbranched polyphenylene structures. Steric hindrance in densely packed di‐ and trihexaarylphenyl substituted units of the (A2 + B3) polyphenylenes results in the decrease of the rotation frequency of phenyl rings in these structures to such an extent that the motion is slow on the 1H NMR time scale. This can be proved both by EXSY and variable‐temperature experiments. Steric constraints were also deduced for the AB2 polyphenylenes from signal line shape.Selected spectra from a VT 1H NMR experiment on polymer 7b (solvent: C2D2Cl4; *–13C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl3).magnified imageSelected spectra from a VT 1H NMR experiment on polymer 7b (solvent: C2D2Cl4; *–13C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl3).
Uniform Sub‐Micron Polymer Spheres Coated with Ag Nanoparticles
Authors: Mohammed Halimatu S. , Shipp Devon A. 
Published: October 2006

AbstractSummary: The synthesis of well‐defined uniform and spherical sub‐micron polymeric spheres, specifically poly[styrene‐co‐(glycidyl methacrylate)] (PSGMA) with a uniform size distribution and surface chemical functionality, is described. It is shown that the surface can be modified with a multi‐amine functional polymer, polyethyleneimine (PEI), most likely through covalent bonding in addition to electrostatic attraction. The PEI acts both as a stabilizing agent and a complexation agent for the deposition of noble metal Ag nanoparticles.Reaction of PSGMA samples with excess PEI, and its TEM image.magnified imageReaction of PSGMA samples with excess PEI, and its TEM image.
Effect of Temperature on Shear‐Induced Anisotropic Structure in Polymer Clay Hydrogels
Authors: Li Jun , Jiang Jun , Li Chunhua , Lin Min Y. , Schwarz Steven A. , Rafailovich Miriam H. , Sokolov Jonathan 
Published: October 2006

AbstractSummary: Shear‐induced orientation of nanoparticles in poly(ethylene oxide)/Laponite RD hydrogels has been investigated by small angle neutron scattering (SANS). As temperature is reduced, anisotropy develops at lower shear rates. The two‐correlation length Debye–Anderson–Brumberger (DAB) model provides a good fit to the experimental data. The deduced short‐range correlation length (≈5 nm) is observed to increase with shear. The long‐range correlation length (≈50 nm) shows a strong directional dependence, and decreases when shear is applied. The relative contribution of long‐range order to the SANS intensity is observed to increase with shear and decrease with temperature.SANS anisotropy |(Iy − Ix)/(Iy + Ix)| as a function of shear rate and q at 2 °C.magnified imageSANS anisotropy |(Iy − Ix)/(Iy + Ix)| as a function of shear rate and q at 2 °C.
Heat transfer at high energy devices with prescribed cooling flow
Authors: Breuer Jens 
Published: October 2006

AbstractWe study the heat transfer from a high‐energy electric device into a surrounding cooling flow. We analyse several simplifications of the model to allow an easier numerical treatment. First, the flow variables velocity and pressure are assumed to be independent from the temperature which allows a reduction to Prandtl's boundary layer model and leads to a coupled nonlinear transmission problem for the temperature distribution. Second, a further simplification using a Kirchhoff transform leads to a coupled Laplace equation with nonlinear boundary conditions. We analyse existence and uniqueness of both the continuous and discrete systems. Finally, we provide some numerical results for a simple two‐dimensional model problem. Copyright © 2006 John Wiley & Sons, Ltd.
Numerical analysis of a model of cure process for composites
Authors: Meliani Salha , Paoli Laetitia 
Published: October 2006

AbstractWe consider a composite material composed of fibres included in a resin which becomes solid when it is heated up (reaction of reticulation). The mathematical modelling of the cure process is given by a kinetic equation describing the evolution of the reaction of reticulation coupled with the heat equation.In this paper, we are interested in the computation of approximate solutions. We propose a family of discretized problems depending on two parameters (β1, β2) ε [0, 1]2 which split the linear and non‐ linear terms in implicit and explicit parts. We prove the stability and convergence of the discretization for any (β1, β2) ε [½, 1 ] × [0, 1]. We present also some numerical results. Copyright © 2006 John Wiley & Sons, Ltd.
Mortality in schizophrenia
Authors: Auquier Pascal , Lançon Christophe , Rouillon Frédéric , Lader Malcolm , Holmes Catriona 
Published: October 2006

AbstractPurposeThe purpose of this article is to describe the current status of knowledge on excess mortality in schizophrenia and its causative factors, and to expand upon previous work evaluating approaches that may reduce mortality rates.MethodsLiterature available since 1995 was identified in a computerized search of the bibliographical databases Medline and Embase, using the topics ‘mortality’ and ‘schizophrenia’, and in a cross‐reference search for articles that were particularly relevant.ResultsSchizophrenia is associated with mortality rates that are two to three times higher than those expected or observed in the general population. This excess of mortality is accounted for by a combination of an increased risk of suicide, in particular in young male patients soon after diagnosis, and more importantly, a higher number of natural deaths. In order to diminish the level of suicide among people with schizophrenia, the majority of research has focused on the identification of risk factors that predispose patients to attempt or commit suicide, while unhealthy styles, polypharmacy and inadequate healthcare have been shown to contribute to the high natural mortality. The link between the use of antipychotics and mortality has not been yet clarified.ConclusionDramatically increased mortality of schizophrenia patients is well established. It is time to move beyond this topic, and work towards interventions that aim at reducing the mortality risk in such patients. Copyright © 2006 John Wiley & Sons, Ltd.
Application of X‐ray Microtomography and Image Processing to the Investigation of a Compacted Granular System
Authors: Fu Xiaowei , Elliott James A. , Bentham A. Craig , Hancock Bruno C. , Cameron Ruth E. 
Published: October 2006

AbstractThis paper outlines a novel technique, based on modern desktop X‐ray microtomography (XMT) and image processing, to visualize and quantitatively investigate powder packing and particle movement during compaction, which relate to materials properties and processing conditions of pharmaceutical tablet manufacture by compaction. This technique has been validated by direct comparison with measurements of particle shape and size by Scanning Electron Microscopy (SEM), and the results are also consistent with predictions made by Discrete Element Method (DEM) computer simulations. The technique has the potential for further quantitative investigation of powder compaction in pharmaceutical powder blends containing multiple components with ranges of particle sizes and shapes.
Watershed Functions Applied to a 3D Image Segmentation Problem for the Analysis of Packed Particle Beds
Authors: Videla Alvaro , Lin Chen‐Luh , Miller Jan D. 
Published: October 2006

AbstractIn an effort to advance the area of particle science and technology the University of Utah has been using cone beam X‐ray microtomography as a major tool for the quantitative three dimensional (3D) analysis of packed beds of multiphase particles. In this regard, efficient imaging algorithms have been developed and applied in order to extend two dimensional (2D) image analysis techniques for the solution of three 3D problems. Based on this research, image analyses of different particle samples were carried out for identification, segmentation, and quantitative volume characterization of irregularly shaped particles. The whole analysis involves acquisition of a 3D image by X‐ray microtomography and a sequence of image processing tools for thresholding, distance transformation, maxima detection using reconstruction by dilation, and a watershed 3D algorithm for segmentation and identification of irregularly shaped particles in three dimensions. Several examples of the 3D analysis for irregularly shaped particles are presented and the results discussed. Application of these algorithms is demonstrated by the determination of coal washability curves.
A Dual Modality Tomography System for Imaging Gas/Solids Flows
Authors: Dyakowski Tom , Johansen Geir A. , Hjertaker Bjorn T. , Sankowski Dominik , Mosorov Volodymyr , Wlodarczyk Jaroslaw 
Published: October 2006

AbstractThe paper presents a novel dual modality reconstruction algorithm (DMR) based on processing data collected from γ‐ray and electrical capacitance tomography systems. The tomograms are shown for noise‐free data as well as for data captured for a gas/solids flow in a vertical channel.
Electrical Resistance Tomography for Suspended Sediment Measurements in Open Channel Flows Using a Novel Sensor Design
Authors: Schlaberg H. Inaki , Baas Jaco H. , Wang Mi , Best Jim L. , Williams Richard A. , Peakall Jeff 
Published: October 2006

AbstractUnderstanding the transport and deposition of sediment (such as sand and clay) is essential to allow the modelling and prediction of sediment dispersal, and the development of depositional morphology, within modern environments and ancient sedimentary basins. Electrical Resistance Tomography (ERT) has previously been used to provide a measure of particle concentration within moving suspensions. ERT measurements normally employ electrodes around a circular boundary of a container that allows measurement of multiple projections. However, measuring the concentration of a flow in a rectangular channel without disturbing the flow cannot use these well‐established sensor rings. This paper investigates the use of a linear sensor array in the channel bed, and a U‐shaped sensor array in the channel bed and walls, to measure spatial and temporal gradients in sediment concentration/conductivity of a channellised flow. To overcome the problems with the effect of sediment‐covered electrodes and the limited number of projection angles of a linear sensor configuration, the properties of a U‐shaped sensor are explored. Due to the additional projection angles in a U‐shaped sensor, improved reconstructions are obtained. This paper presents the first measurements of suspended sediment concentration and sediment deposition and test objects using linear and U‐shaped tomographic sensors.
Visualisation of Bubbly Velocity Distribution in a Swirling Flow Using Electrical Resistance Tomography
Authors: Wang Mi , Lucas Gary , Dai Yunfeng , Panayotopoulos Nikolaos , Williams Richard A. 
Published: October 2006

AbstractThis paper describes a dual‐plane Electrical Resistance Tomography (ERT) system for measuring local air volume fraction and 3‐D velocity distribution in gas‐liquid flows. An implementation based on a so‐called ‘best‐correlated pixels' method has been developed. Applying the 3‐D velocity implementation to tomographic data sets obtained from an air‐water swirling flow, axial, angular and radial velocity profiles have been successfully extracted. With the volume fraction distribution reconstructed using the “sensitivity theory based inverse solution using conjugate gradient” (SCG) method, the dispersed phase flow volumetric rate can be obtained. The experimental results obtained using the ERT system are in good agreement with the measurements obtained using a local probing technique.
Mechanism of the decrease of barriers for oxygen ionic conductivity in nanocrystalline ceramics
Authors: Glinchuk M. D. , Bykov P. I. , Hilczer B. 
Published: October 2006

AbstractWe calculate the influence of surface tension on the barriers for oxygen ionic conductivity in nanograin ceramics. Namely, we evaluate the activation energy for diffusion of oxygen ions via its vacancies. In our model, latter vacancies have been considered as dilatational centers. We have shown, that the activation energy decreases with nanoparticle size decreasing. We derive the distribution function of activation energy on the base of distribution of nanoparticle sizes. We obtain analytical expressions for dependence of ionic conductivity on the temperature and nanograin sizes. The obtained expressions describe the observed behaviour of oxygen conductivity in nanograin ceramics of ZrO2:16% Y pretty good. Our theoretical studies show that the surface tension in nanoparticles is indeed a physical mechanism responsible for the essential enhancement of the oxygen ionic conductivity observed in nanograin samples, where the main contribution to the conductivity goes from the region near the particle surface. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Geometry dependence of the conductance oscillations of monovalent atomic chains
Authors: Major Péter , Tichy Géza , Cserti József , García‐Suárez Víctor Manuel , Sirichantaropass Skon 
Published: October 2006

AbstractUsing a tight binding model we calculate the conductance of monovalent atomic chains for different contact geometries. The leads connected to the chains are modelled as semi‐infinite fcc lattices with different orientations and couplings. Our aim is twofold: To check the validity of a three‐parametric conductance formula for differently oriented leads, and to investigate the geometry dependence of the conductance oscillations. We show that the character of these oscillations depends strongly on the geometry of the chain–lead coupling. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Functionalization of multi‐walled carbon nanotubes: Direct proof of sidewall thiolation
Authors: Čech Jiří , Curran Seamus A. , Zhang Donghui , Dewald James L. , Avadhanula Aditya , Kandadai Madhu , Roth Siegmar 
Published: October 2006

AbstractWe analyzed structural changes and clearly revealed position and character of newly attached, sulfur containing, functional groups. Multi‐walled carbon nanotubes (MWCNTs) have been first exposed to harsh acid treatment to induce defects and oxygen containing hydroxyl and carboxyl groups. Such tubes were imaged by High Resolution Transmission Electron Microscopy (HRTEM) to visualize the structural changes that have occurred to due to extensive acid‐treatment. Consequently the MWCNT were thiolated using P4S10 and we used Electron Energy Loss Spectroscopy (EELS) to characterize the changes and to visualize sulfur containing sites on the nanotubes due to sidewall functionalization. The determined sulfur content is 0.6%. We also present vibrational modes around 500 cm–1. Such modes appears only on thiolated MWCNT and may be explained by creation of characteristic carbon–sulfur bonds. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparative structural–vibrational study of nano‐urchin and nanorods of vanadium oxide
Authors: Lavayen V. , O'Dwyer C. , Santa Ana M. A. , Newcomb S. B. , Benavente E. , González G. , Sotomayor Torres C. M. 
Published: October 2006

AbstractWe present a comparative structural–vibrational study of nanostructured systems of V2O5: nano‐urchin (VONURs) which are spherical structures composed of a radially oriented array of VOx nanotubes (VOx‐NTs) with a volumetric density of ∼40 sr–1, and vanadium oxide nanorods (VOx‐NRDs) with an average length of ∼100 nm. The Raman scattering spectrum of the nano‐urchin exhibits a band at 1014 cm–1 related to the distorted gamma conformation of the vanadium pentoxide (γ‐V5+). The infrared vibrational spectra of the nanorods sample also exhibit a distorted laminar V2O5 structure with evidence observed for quadravalent V4+ species at 921 cm–1. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Origin of superconductivity of CaC6 and of other intercalated graphites
Authors: Calandra Matteo , Mauri Francesco 
Published: October 2006

AbstractBy intercalation of donor the low conductivity of graphite can be enhanced and a superconducting state can occur at low temperature. The first discovered superconductors were alkali‐intercalated compounds, with a critical temperatures (T c) of the order of 1 K. In 2005 we learned with surprise that Ca intercalated graphite (CaC6) is a superconductor with the sizable T c of 11.5 K. Using density functional theory we demonstrate that superconductivity in CaC6 is phonon‐mediated with an electron–phonon coupling λ equal to 0.83 and a phonon‐frequency logarithmic‐average equal to 25 meV. Superconductivity is mostly due C vibrations perpendicular and Ca vibrations parallel to the graphite layers. A non zero electron–phonon coupling for these modes can not be associated to the Fermi surface of the graphite pi bands but requires the presence of a second Fermi surface associated to the intercalant atoms. This result suggests a general mechanism for the occurrence of superconductivity in intercalated graphite. In order to stabilize a superconducting state it is necessary to have an intercalant Fermi surface since the simple doping of the π bands in graphite does not lead to a sizeable electron–phonon coupling. This condition occurs if the intercalant band is partially occupied, i.e. when the intercalant is not fully ionized. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electron spin resonance of single‐walled carbon nanotubes and related structures
Authors: Náfrádi B. , Nemes N. M. , Fehér T. , Forró L. , Kim Y. , Fischer J. E. , Luzzi D. E. , Simon F. , Kuzmany H. 
Published: October 2006

AbstractWe report new results on the electron spin resonance of single walled carbon nanotubes, peapods and double walled carbon nanotubes. A small ESR line is present in well purified samples and its temperature dependence reveals a striking ‘super‐Curie’ paramagnetic rise. In addition, we identify a narrower line in peapod and DWNT samples, which displays similar behavior. The linewidth of both inner and outer species are metallic and the outer tube's resonance broadens upon growth of the inner tubes. We observe a sudden decrease of relaxation rate below 20 K, in accordance with the opening of a spin‐gap. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aharonov–Bohm effects on conductivity in carbon nanotubes: A tool for determination of a gap due to strain and curvature
Authors: Nakanishi Takeshi , Ando Tsuneya 
Published: October 2006

AbstractThe Boltzmann conductivity is calculated for carbon nanotubes in the presence of an Aharonov–Bohm magnetic flux. Effects of strain or curvature manifest themselves as a prominent conductivity peak as a function of the flux. The appearance of the peak corresponds to the absence of backscattering in metallic linear bands and makes it possible to determine a gap due to curvature and strain. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)