Search results for "conduct"
showing 10 items of 4412 documents
Quantification of intracranial contribution to rheoencephalography by a numerical model of the head
2000
Abstract Objectives : Partial contributions of intracranial and extracranial circulation to rheoencephalography (REG) remain uncertain. The main goal of this work is to determine theoretically the capability of REG techniques to reflect intracranial blood flow. Methods : Head and current injection electrodes were computationally modeled to assess REG sensitivity to brain and scalp conductivity changes. Data obtained were related to tissue perfusions to calculate the partial contribution of cerebral blood perfusion to REG I, REG II and monopolar REG and to assess their amplitudes. Results : When REG I and monopolar REG were used, the theoretical maximum of intracranial contribution was reach…
ChemInform Abstract: Electrical and Mechanical Breakdown of Anodic Films on Tungsten in Aqueous Electrolytes.
1988
Abstract Different types of breakdown are reported to occur during the galvanostatic growth of WO3 films in different aqueous electrolytes. Stresses inside the growing film cause the occurrence of cracks at a critical thickness which varies with the anodizing solution. The electrical breakdown is caused by avalanche ionization of the electronic current inside the film. The influence of the different experimental parameters on both the mechanical and the electrical breakdown voltages is discussed. For the electrical breakdown a model is proposed which explains the dependence of the sparking voltage on the electrolyte resistivity by assuming a double layer effect on the oxygen evolution react…
Acidic Ionic Liquids as Composite Forming Additives for Ion-conducting Materials
2013
This paper represents the material conductivity investigation of several AILs (Acidic Ionic Liquids) containing an alkane sulfonic acid group covalently bonded to pyridine and N–alkylimidazole cations. Three different anions (HSO4-, H2PO4- and TsO-) have been introduced in the structure of ionic liquids to evaluate the impact of this factor on material conductivity. Ion conductivity values in all studied ionic liquids obtained from impedance measurements in temperature range from 20 to 120 °C. Values of electroconductivity depending on ionic liquid's structure vary in rage from 1.3410−5 to 1.0510−2 S/cm at 25 °C.
Single particle jumps and correlated ionic motions in glass-ceramics
1993
Using impedance spectroscopy, the ion transport in poorly Li-conducting aluminosilicate glass ceramics and their precursor glasses has been measured for temperatures 50 K < T < 550 K and covering a frequency range of more than 14 decades from 10 mHz up to 3 THz. In addition to the familiar cooperative ionic motion dominating at high temperatures, for the first time dielectric relaxation due to elementary hopping processes is observed well below room temperature.
A chiral molecular conductor: synthesis, structure, and physical properties of [ET]3[Sb2(L-tart)2].CH3CN (ET = bis(ethylendithio)tetrathiafulvalene; …
2004
The salt [ET](3)[Sb(2)(L-tart)(2)].CH(3)CN (1) has been obtained by electrocrystallization of the organic donor bis(ethylendithio)tetrathiafulvalene (ET or BEDT-TTF) in the presence of the chiral anionic complex [Sb(2)(L-tart)(2)](2-) (L-tart = (2R,3R)-(+)-tartrate). This salt crystallizes in the chiral space group P2(1)2(1)2(1) (a = 11.145(2) angstroms, b = 12.848(2) angstroms, c = 40.159(14) angstroms, V = 5750.4(14) angstroms(3), Z = 4) and is formed by alternating layers of the anions and of the organic radicals in a noncentrosymmetric alpha-type packing. This compound shows a room temperature electrical conductivity of approximately 1 S.cm(-1) and semiconducting behavior with an activa…
Considering lithium-ion battery 3D-printing via thermoplastic material extrusion and polymer powder bed fusion
2021
Abstract In this paper, the ability to 3D print lithium-ion batteries through Pmnbspace thermoplastic material extrusion and polymer powder bed fusion is considered. Focused on the formulation of positive electrodes composed of polypropylene, LiFePO4 as active material, and conductive additives, advantages and drawbacks of both additive manufacturing technologies, are thoroughly discussed from the electrochemical, electrical, morphological and mechanical perspectives. Based on these preliminary results, strategies to further optimize the electrochemical performances are proposed. Through a comprehensive modeling study, the enhanced electrochemical suitability at high current densities of va…
ChemInform Abstract: Electrical Conductive Coordination Polymers
2012
Coordination polymers are currently one of the hottest topics in Inorganic and Supramolecular Chemistry. This critical review summarizes the current state-of-the-art on electrical conductive coordination polymers (CPs), also named metal–organic frameworks (MOFs). The data were collected following two sort criteria of the CPs structure: dimensionality and bridging ligands (151 references).
High performance PA6/CNTs nanohybrid fibers prepared in the melt
2012
Commercial and home-made carbon nanotubes (CNTs) were plasma treated under oxygen atmosphere and then added to polyamide 6 (PA6) in order to prepare fibres by melt spinning. For comparison, pristine nanofillers were used too. The effect of functionalization and of filler characteristics on the morphological, rheological, mechanical and electrical properties of the fibres was studied by TEM and SEM, rheological measurements, tensile and electrical conductivity tests. The results demonstrated that the functionalization led to a better mechanical performance and the morphological analysis confirmed that the adhesion, the dispersion and the alignment of the nanotubes within the polymer matrix w…
Theory of nucleation and crystal growth of polymers in concentrated solutions
1974
ABSTRACT The process of crystallization in concentrated solutions depends strongly on the rate of crystallization and the rate of long range diffusion of the polymer chains. If the crystallization proceeds slowly compared to diffusion, this type of crystal nucleus will be formed for which the free energy of nucleation is smallest. By taking into account entropy effects which are characteristic for chain molecules one can show that the crystal with smallest free energy of nucleation is a crystal with almost regular chain folds on the surfaces. The influence of supercooling, concentration and molecular weight on the thickness and growth rate of such crystals is discussed. If the crystallizati…
FT-IR investigation of the state of iron (III) chloride clusters confined in AOT reverse micelles dispersed in carbon tetrachloride
2007
The state of the water-soluble salt iron(III) chloride in AOT reverse micelles dispersed in carbon tetrachloride has been investigated by FT-IR spectroscopy. Interestingly, while the entrapment of a lot of water-soluble inorganic salts in AOT reverse micelles requires preliminarily the presence of significant amounts of water within the micellar core, solubilization of FeCl3 occurs without the need to add water in the micellar solution reaching the very high solubility value, expressed as the maximum salt-to-surfactant molar ratio, of 1.30. The analysis of the spectral features of the investigated samples leads to hypothesize that iron(III) chloride is confined within the reverse micellar c…