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Conductive Properties (conductive + property)
Selected AbstractsSynthesis, Characterization and Ionic Conductive Properties of Phosphorylated Chitosan MembranesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 5-6 2003Ying Wan Abstract Phosphorylated chitosan membranes were prepared from the reaction of orthophosphoric acid and urea on the surface of chitosan membranes in N,N -dimethylformamide. Their ionic conductivity in the wet state was investigated. Chemical modifications contributed to improved ionic conductivities of the chitosan membranes. Compared to the unmodified chitosan membranes, it was found that hydrated phosphorylated chitosan membranes with an appropriate phosphorus content showed an increasing ionic conductivity of about one order of magnitude. The phosphorylation reaction mechanism was explained based on 13C and 31P NMR measurements. It was also observed that the crystallinity of the phosphorylated chitosan membranes and the corresponding swelling indices were changed pronouncedly, but these membranes did not lose either their tensile strength or thermal stability to a significant degree in comparison with the unmodified chitosan membranes. Possible reaction mechanism for preparation of phosphorylated chitosan membranes. [source] Unprecedented Binary Semiconductors Based on TCNQ: Single-Crystal X-ray Studies and Physical Properties of Cu(TCNQX2) X=Cl, BrADVANCED MATERIALS, Issue 9 2010Nazario Lopez Single crystals of a new structure typefor the M+(TCNQ),, binary family are isolated from reactions of dihalogenated TCNQ derivatives and CuI ions (see figure; Cu: pink C: black, N: blue, Br: orange, H: light blue). The new compound Cu(TCNQCl2) exhibits the highest conductivity of the M+(TCNQ),, series to date, despite the larger separation of TCNQCl2 units in the stacks. Conductive properties of Cu(TCNQX2) where X,=,Cl, Br is attributed to charge-carrier transport through copper ions, which is unprecedented in M+(TCNQ),, materials. [source] A General Electrochemical Strategy for Synthesizing Charge-Transfer Complex Micro/NanowiresADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Liang Ren Abstract Universal strategies for synthesizing one-dimensional organic nanomaterials are of fundamental importance in the development of more flexible, cheaper and lighter electronics. Charge-transfer (CT) complexes, the major kind of organic conductors, are in the long-term attractive materials owing to their unique crystal structures and conductive properties. In this article, a general strategy for the synthesis of CT complex micro/nanowires based on the localized nanoelectrochemistry using tiny carbon nanotube (CNT) electrodes is presented. This strategy is successfully demonstrated over 12 typical CT complexes, and a general rule for the preparation of various kinds of CT complex micro/nanowires is summarized. The CT complex micro/nanowires thus synthesized have high aspect ratios and long lengths as compared with traditional macroscopic planar electrodes, originating from the one-dimensional structural feature with fewer or no defects and the ultrasmall surface area of the CNT. This work provides a more versatile material basis for the fundamental and application studies of low-dimensional organic conductor materials. [source] Amitriptyline has a dual effect on the conductive properties of the epithelial Na channelJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2002Florentina Pena This study was undertaken with the aim of testing the action of amitriptyline on the epithelial Na channel (ENaC), which belongs to the same family (Deg/ENaC) as ASICs (acid-sensing ion channels) and many other putative members in the brain. We assumed that, having a common protein structure, characterization of the amitriptyline-ENaC interaction could help to elucidate the analgesic mechanism of this tricyclic antidepressant. Na-channel characteristics were derived from the analysis of blocker-induced lorentzian noise produced by amiloride. The effect of amitriptyline, present in the mucosal bathing solution, on the transepithelial short-circuit current (1sc) and conductance (Gt), and on the blocker-induced noise of apical Na channels, was studied on isolated ventral skin of the frog Rana ridibunda. Amitriptyline exerted a dual effect on the macroscopic short-circuit current and conductance of the epithelia, increasing these two parameters in the concentration range 0.1,50 ,M, while at higher concentrations (100,1000 ,M) it showed an inhibitory action. The decrease in the association rate (k01) of amiloride to the apical Na channels from 15.6 ± 4.2 ,M,1 S,1 in control Cl-Ringer to 7.4 ± 1.7 ,M,1 S,1 at 200 ,M amitriptyline in a concentration-dependent manner suggests a competitive binding of amitriptyline to the pyrazine ring binding site for amiloride. [source] Cavotricuspid Isthmus Ablation with Large-Tip Gold Alloy Versus Platinum-Iridium-Tip Electrode CathetersPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009ATTILA KARDOS M.D., Ph.D. Background: Gold has excellent electrical conductive properties and creates deeper and wider lesions than platinum-iridium during radiofrequency (RF) ablation in vitro. We tested the maximum voltage-guided technique (MVGT) of cavotricuspid isthmus (CTI) ablation using two 8-mm tip catheters containing gold (group G) or platinum-iridium (group PI). Methods: We enrolled 31 patients who underwent CTI ablation. In group G (n = 15) CTI ablation was performed with a gold-tip ablation catheter, while in group PI (n = 16) a platinum-iridium tip was used. Ablation was guided by CTI potentials with the highest amplitude until achievement of bidirectional block (BIB). If BIB was not achieved after 10 RF applications, RF was delivered via a 3.5-mm irrigated-tip catheter. Success rate, procedure duration, duration of fluoroscopic exposure, and number of RF applications were measured. Results: BIB was achieved in all patients in group G, while in group PI an irrigated tip was used in four patients (0% vs 25%, P < 0.001). These four patients required a total of 21 additional RF applications (5.25 ± 2.22). Procedure time (56.4 ± 12 vs 73.1 ± 15 minutes P < 0.05) and fluoroscopic explosure (4.9 ± 2.3 vs 7.1 ± 3.8 minutes, P < 0.01) were shorter in group G than in group PI. Mean number of RF applications was lower (4.6 ± 1.9 vs 6.6 ± 3.1 P < 0.001) and total RF duration shorter (280 ± 117 vs 480 ± 310 seconds) in group G than in group PI. No difference was observed in the number of recurrences at a 6 month-follow up (1 in group G vs 1 in group PI). Conclusion: Using the MVGT of CTI ablation, gold-tip catheters were associated with shorter procedural and fluoroscopic times, and fewer RF applications. [source] Electrical conductivity and rheological behavior of multiphase polymer composites containing conducting carbon blackPOLYMER ENGINEERING & SCIENCE, Issue 11 2008Qinghua Zhang Multiphase polymer composites of carbon black (CB), polypropylene (PP) and low density polyethylene (LDPE) were prepared by melt-mixing method to reduce the amount of CB in the conductive composites. SEM images showed that CB preferably located in LDPE phase and formed electrically conductive path. The measurement of conductive properties showed that the ternary materials possessed lower percolation than binary composites of CB/PP or CB/LDPE, the former was ,6 wt% and the latter was 9,10 wt%. Positive temperature coefficient (PTC) effects of the binary and ternary composites were investigated, indicating that the latter exhibited a relatively high PTC intensity. A rheological percolation estimated by a power law function is 2.66 wt% of CB loading, suggesting an onset of solid-like behavior at low frequencies. This difference between the electrical and rheological percolation thresholds may be understood in terms of the smaller CB,CB distance required for electrical conductivity as compared with that required to impede polymer mobility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Polymeric composites for use in electronic and microwave devicesPOLYMER ENGINEERING & SCIENCE, Issue 3 2004Alexandre Moulart The dielectric and conductive properties of thermoplastic (ABS) composites filled with ceramic powder (barium titanate), conductive powders (carbon black, copper) and conductive fibers (carbon, steel) were investigated for use in electromagnetic crystals and microwave devices. Barium titanate/ABS composites were produced that had dielectric constants over 8 and loss tangents of 0.01, which are the requirements for electromagnetic crystals. Carbon black/ABS and steel fiber/ABS composites were obtained with conductivities suitable for electromagnetic shielding (over 10,3 S/cm). Fused decomposition modeling was tested as a method for building electromagnetic crystals and showed promising results. Polym. Eng. Sci. 44:588,597, 2004. © 2004 Society of Plastics Engineers. [source] Conductive composites of UHMWPE and ceramics based on the segregated network conceptPOLYMER ENGINEERING & SCIENCE, Issue 1 2000J. Bouchet The manufacturing of composites of ultra high molecular weight polyethylene and ceramics with conductive properties has been investigated. Attention has been focused on the lowering of the amount of filler necessary to achieve low resistivity. Using segregated networks, mixing large polymer particles and submicron metal or conductive ceramic particles may be an interesting route, provided that the processing method enables to generate the desired structures. Because sintering avoids the intimate blending of the components, it is a suitable technique for this aim. The combined effects of temperature, pressure and sintering time have been investigated. The influence of the blending of the solids on the covering of the polyethylene particles before the sintering has also been pointed out. The typical features related to the concept of a segregated network are discussed in connection with the morphologies of the polymer and ceramic particles. The successful application of the reduction of the percolation threshold by a segregated network in conductive composites of polymer and metallic particles is described. [source] From carbon nanotube coatings to high-performance polymer nanocompositesPOLYMER INTERNATIONAL, Issue 4 2008Stéphane Bredeau Abstract Since their discovery at the beginning of the 1990s, carbon nanotubes (CNTs) have been the focus of considerable research by both academia and industry due to their remarkable and unique electronic and mechanical properties. Among numerous potential applications of CNTs, their use as reinforcing materials for polymers has recently received considerable attention since their exceptional mechanical properties, combined with their low density, offer tremendous opportunities for the development of fundamentally new material systems. However, the key challenge remains to reach a high level of nanoparticle dissociation (i.e. to break down the cohesion of aggregated CNTs) as well as a fine dispersion upon melt blending within the selected matrices. Therefore, this contribution aims at reviewing the exceptional efficiency of CNT coating by a thin layer of polymer as obtained by an in situ polymerization process catalysed directly from the nanofiller surface, known as the ,polymerization-filling technique'. This process allows for complete destructuring of the native filler aggregates. Interestingly enough, such surface-coated carbon nanotubes can be added as ,masterbatch' in commercial polymeric matrices leading to the production of polymer nanocomposites displaying much better thermomechanical, flame retardant and electrical conductive properties even at very low filler loading. Copyright © 2007 Society of Chemical Industry [source] | |||||||||||||||||||||||||