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Conductivity Properties (conductivity + property)
Selected AbstractsChemInform Abstract: Effect of Thermal Treatment on the Electronic Conductivity Properties of Cobalt Spinel Phases Synthesized by Electro-Oxidation in Ternary Alkaline Electrolyte (KOH, LiOH, NaOH).CHEMINFORM, Issue 6 2009Myriam Douin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Improved EEG source analysis using low-resolution conductivity estimation in a four-compartment finite element head modelHUMAN BRAIN MAPPING, Issue 9 2009Seok Lew Abstract Bioelectric source analysis in the human brain from scalp electroencephalography (EEG) signals is sensitive to geometry and conductivity properties of the different head tissues. We propose a low-resolution conductivity estimation (LRCE) method using simulated annealing optimization on high-resolution finite element models that individually optimizes a realistically shaped four-layer volume conductor with regard to the brain and skull compartment conductivities. As input data, the method needs T1- and PD-weighted magnetic resonance images for an improved modeling of the skull and the cerebrospinal fluid compartment and evoked potential data with high signal-to-noise ratio (SNR). Our simulation studies showed that for EEG data with realistic SNR, the LRCE method was able to simultaneously reconstruct both the brain and the skull conductivity together with the underlying dipole source and provided an improved source analysis result. We have also demonstrated the feasibility and applicability of the new method to simultaneously estimate brain and skull conductivity and a somatosensory source from measured tactile somatosensory-evoked potentials of a human subject. Our results show the viability of an approach that computes its own conductivity values and thus reduces the dependence on assigning values from the literature and likely produces a more robust estimate of current sources. Using the LRCE method, the individually optimized four-compartment volume conductor model can, in a second step, be used for the analysis of clinical or cognitive data acquired from the same subject. Hum Brain Mapp, 2009. © 2008 Wiley-Liss, Inc. [source] Effects of the filler loading and aging time on the mechanical and electrical conductivity properties of carbon black filled natural rubberJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008A. R. Azura Abstract The effects of the filler loading and aging time on the mechanical and electrical conductivity properties of natural rubber were investigated. In this work, carbon black (type N220) was used as a filler, and its loading was varied from 0 to 50 phr. The mechanical properties (e.g., the tensile strength and catastrophic tearing energy) increased with a filler loading up to a certain loading, and a decrease in the mechanical properties was observed with higher filler loadings. The tensile strength and catastrophic tearing energy of the aged samples decreased after 3 and 6 days of aging at 100°C. The results for the electrical conductivity properties of unaged samples showed a percolation threshold at 20 phr, and the values were consistent with further filler loadings. After aging, the percolation threshold was still maintained at 20 phr. The morphologies of unaged and aged samples were significantly different: holes were observed to occur in the aged samples. This might have been due to the movement of fillers when the materials were subjected to heat, and this subsequently influenced the mechanical properties of the natural rubber composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of PEDOT Nanoparticles and Vesicles by Dispersion Polymerization in Alcoholic MediaMACROMOLECULAR RAPID COMMUNICATIONS, Issue 17 2006Muhammad Mumtaz Abstract Summary: The synthesis of PEDOT nanoparticles and vesicles by dispersion polymerization in a methanol/water mixture (3/2, v/v) is reported, using either ammonium persulfate or iron(III) p -toluenesulfonate as oxidants and , -EDOT-PEO as a reactive stabilizer. The influence of the oxidant as well as the , -EDOT-PEO molar mass and concentration on the core-shell particle morphology and conductivity properties have been investigated. PEDOT particles with conductivities up to 1.5,×,10,2 S,·,cm,1 have been obtained in high yield. TEM image of PEDOT vesicles prepared using PEO-based stabilizers of 25,000 g,·,mol,1 in water/methanol mixture (2:3 v/v) at room temperature using ammonium persulfate as an oxidant. [source] Schiff base substitute polyphenol and its metal complexes derived from o -vanillin with 2,3-diaminopyridine: synthesis, characterization, thermal, and conductivity propertiesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2008smet Kaya Abstract Poly-2,3 - bis[(2-hydroxy-3-methoxyphenyl)methylene]diamino pyridine (PHMPMDAP) that a new Schiff base polymer has been synthesized and characterized by spectroscopy, elemental, and thermal analyses techniques. This azomethine polymer was found to form complexes readily with Cu(II), Zn(II), Co(II), Pb(II), and Fe(II). From IR and UV-Vis studies, the phenolic oxygen and imine nitrogen of the ligand were found to be the coordination sites. Thermogravimetric analysis (TGA) data indicate the polymer to be more stable than the monomer. The structure of the polymer obtained was confirmed by FT-IR, UV-Vis, 13C-NMR, and 1H-NMR. Characterization was undertaken by TGA, size exclusion chromatography (SEC), and solubility tests. Also, electrical conductivities of PHMPMDAP and polymer,metal complexes are measured by four probe technique. Copyright © 2008 John Wiley & Sons, Ltd. [source] Erratum: Schiff base substitute polyphenol and its metal complexes derived from o-vanillin with 2,3-diaminopyridine: synthesis, characterization, thermal, and conductivity propertiesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2008smet Kaya No abstract is available for this article. [source] Disorder in Ag7GeSe5I, a superionic conductor: temperature-dependent anharmonic structural studyACTA CRYSTALLOGRAPHICA SECTION B, Issue 1 2008Stéphanie Albert A temperature-dependent structural investigation of the substituted argyrodite Ag7GeSe5I has been carried out on a single crystal from 15 to 475,K, in steps of 50,K, and correlated to its conductivity properties. The argyrodite crystallizes in a cubic cell with the space group. The crystal structure exhibits high static and dynamic disorder which has been efficiently accounted for using a combination of (i) Gram,Charlier development of the Debye,Waller factors for iodine and silver, and (ii) a split-atom model for Ag+ ions. An increased delocalization of the mobile d10 Ag+ cations with temperature has been clearly shown by the inspection of the joint probability-density functions; the corresponding diffusion pathways have been determined. [source] Mudstone compaction curves in basin modelling: a study of Mesozoic and Cenozoic Sediments in the northern North SeaBASIN RESEARCH, Issue 3 2010Ø. Marcussen ABSTRACT Basin modelling studies are carried out in order to understand the basin evolution and palaeotemperature history of sedimentary basins. The results of basin modelling are sensitive to changes in the physical properties of the rocks in the sedimentary sequences. The rate of basin subsidence depends, to a large extent, on the density of the sedimentary column, which is largely dependent on the porosity and therefore on the rate of compaction. This study has tested the sensitivity of varying porosity/depth curves and related thermal conductivities for the Cenozoic succession along a cross-section in the northern North Sea basin, offshore Norway. End-member porosity/depth curves, assuming clay with smectite and kaolinite properties, are compared with a standard compaction curve for shale normally applied to the North Sea. Using these alternate relationships, basin geometries of the Cenozoic succession may vary up to 15% from those predicted using the standard compaction curve. Isostatic subsidence along the cross-section varies 2.3,4.6% between the two end-member cases. This leads to a 3,8% difference in tectonic subsidence, with maximum values in the basin centre. Owing to this, the estimated stretching factors vary up to 7.8%, which further gives rise to a maximum difference in heat flow of more than 8.5% in the basin centre. The modelled temperatures for an Upper Jurassic source rock show a deviation of more than 20 °C at present dependent on the thermal conductivity properties in the post-rift succession. This will influence the modelled hydrocarbon generation history of the basin, which is an essential output from basin modelling analysis. Results from the northern North Sea have shown that varying compaction trends in sediments with varying thermal properties are important parameters to constrain when analysing sedimentary basins. [source] Evaluation of Process-Induced Dimensional Changes in the Membrane Structure of Biological Cells Using Impedance MeasurementBIOTECHNOLOGY PROGRESS, Issue 3 2002Alexander Angersbach The impact of high intensity electric field pulses, high hydrostatic pressure, and freezing-thawing on local structural changes of the membrane was determined for potato, sugar beet tissue, and yeast suspensions. On the basis of the electrophysical model of cell systems in biological tissues and suspensions, a method was derived for determining the extent of local damage of cell membranes. The method was characterized by an accurate and rapid on-line determination of frequency-dependent electrical conductivity properties from which information on microscopic events on cellular level may be deduced. Evaluation was based on the measurement of the relative change in the sampleapos;s impedance at characteristically low ( fl) and high ( fh) frequencies within the ,-dispersion range. For plant and animal cells the characteristic frequencies were fl , 5 kHz and fh > 5 MHz and for yeast cells in the range fl , 50 kHz and fh > 25 MHz. The observed phenomena were complex. The identification of the underlying mechanisms required consideration of the time-dependent nature of the processing effects and stress reactions of the biological systems, which ranged from seconds to several hours. A very low but significantly detectable membrane damage (0.004% of the total area) was found after high hydrostatic pressure treatment of potato tissue at 200 MPa. The membrane rupture in plant tissue cells was higher after freezing and subsequent thawing (0.9% of total area for potato cells and 0.05,0.07% for sugar beet cells determined immediately after thawing), which increased substantially during the next 2 h. [source] Effect of addition of organic microspheres on proton conductivity property of sulfonated poly(arylene ether sulfone) membraneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Cui Liang Abstract Sulfonated poly(arylene ether sulfone) (SPAES)/polystyrene(PS) and SPAES/polystyrene sulfonic acid (PSSA) composite membranes were studied for a proton-exchange membrane used in a fuel cell. PS microspheres were synthesized by emulsion polymerization. PSSA microspheres with 5.3 mmol/g ion-exchange capacity (IEC) were prepared by sulfonation of PS microspheres. The composite membranes were prepared by solution casting. SPAES/PSSA composite membranes showed higher proton conductivity than a SPAES membrane because of the IEC improved by adding PSSA. Although the addition of PSSA also brought about the increase of a methanol permeability, the proton/methanol selectivity defined as the ratio of the proton conductivity to the methanol permeability was improved at low humidity by adding 5 wt % of PSSA microspheres. Differential scanning calorimetry results indicated that the amount of free water varied in the cases of the addition of the two kinds of organic microspheres. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] | ||||||||||||||||