Search results for "CONDUCTIVITY"
showing 10 items of 1988 documents
First observation of the doubly charmed baryon decay Ξcc++→Ξc+π+
2018
The doubly charmed baryon decay Ξcc++→Ξc+π+ is observed for the first time, with a statistical significance of 5.9σ, confirming a recent observation of the baryon in the Λc+K−π+π+ final state. The data sample used corresponds to an integrated luminosity of 1.7 fb−1, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV. The Ξcc++ mass is measured to be 3620.6±1.5(stat)±0.4(syst)±0.3(Ξc+) MeV/c2 and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be [B(Ξcc++→Ξc+π+)×B(Ξc+→pK−π+)]/[B(Ξcc++→Λc+K−π+π+)×B(Λc+→pK−π+)]=0.035±0.009(stat)±0.003(syst).
Activation by Acidic pH of CLC-7 Expressed in Oocytes from Xenopus laevis
2002
ClC chloride channels are important in diverse physiological functions such as transepithelial transport, cell volume regulation, excitability, and acidification of intracellular organelles. We have investigated the expression of CLC-7 in oocytes from Xenopus laevis with the two electrode voltage clamp technique and Western blot analysis. Using a specific antibody against CLC-7, we found an approximately 80 kDa protein in oocytes, previously injected with CLC-7-cRNA. In voltage clamp experiments on ClC-7-cRNA-injected oocytes, no current changes were detected at normal pH (7.4). However, acidification of the Ringer solution to pH values between 6 and 4 revealed strong currents which reverse…
Electrochemical impedance spectroscopy of conductor-insulator composite electrodes: properties in the blocking and diffusive regimes
1998
Abstract The electrochemical response of graphite + high-density polyethylene composite electrodes as a function of the conductivity load was investigated. Percolation theory was used in order to explain the electrochemical behaviour of this type of composite electrode. In the blocking regime the electrochemical impedance of this electrode material behaved as R 0 + q · ( ω j) − η , where R 0 represents the uncompensated resistance of the cell. Its value depended on the graphite volume proportion ( ν ) with a power law R 0 ∞ ( ν — ν c ) − t with a critical exponent t = 3.2 ± 0.1 which is close to the mean field value, t = 3. With potassium chloride concentrations greater than 0.7 M, the unco…
High-Quality Metal–Organic Framework Ultrathin Films for Electronically Active Interfaces
2016
Currently available methodologies arguably lack the exquisite control required for producing metal-organic framework (MOF) thin films of sufficient quality for electronic applications. By directing MOF transfer with self-assembled monolayers (SAMs), we achieve very smooth, homogeneous, highly oriented, ultrathin films across millimeter-scale areas that display moderate conductivity likely due to electron hopping. Here, the SAM is key for directing the transfer thereby enlarging the number and nature of the substrates of choice. We have exploited this versatility to evolve from deposition onto standard Si and Au to nonconventional substrates such as ferromagnetic Permalloy. We believe that t…
Comparison of Procedures to estimate Steady Flow Rate in Field Measurement of Saturated Hydraulic Conductivity by the Guelph Permeameter Method
1999
Abstract Different procedures for estimating steady flow rate during field application of the Guelph permeameter method were compared in terms of field-saturated hydraulic conductivity K fs and equilibration time t s estimates. The steady flow rate was evaluated by the slope of the linear portion of the cumulative drop in water level in the permeameter reservoir versus time plot (reference procedure) and by approximate procedures that use the first three or four consecutive values of the rate of fall of the water level equal or differing by less than a given percentage. The influence of the selected time interval between two successive readings ( Δt =2 or 10 min) at the permeameter was also…
Hydric, thermal and mechanical properties of self-compacting concrete containing different fillers
2008
Abstract Water vapor diffusion coefficient, water absorption coefficient, water permeability, thermal conductivity, compressive strength and freeze resistance properties of two self-compacting concretes (SCC) containing limestone filler and fly ash are determined in the paper. The results indicate that strength development is faster in the material containing limestone filler but after 90 days the strength values in both materials are almost the same. Liquid water transport and heat transport are faster in SCC with limestone filler while the water vapor transport is faster in the material containing fly ash. This corresponds well with the much better freeze resistance of the material with f…
Permeability and conductivity for reconstruction models of porous media
2001
The purpose of this paper is to examine representative examples of realistic three-dimensional models for porous media by comparing their geometrical and transport properties with those of the original experimental specimen. The comparison is based on numerically exact evaluations of permeability, formation factor, porosity, specific internal surface, mean curvature, Euler number, local porosity distributions, and local percolation probabilities. The experimental specimen is a three-dimensional computer tomographic image of Fontainebleau sandstone. The three models are examples of physical and stochastic reconstructions for which many of the geometrical characteristics coincide with those o…
Effect of Aspect ratio and water contamination on the electric properties of nanostructured insulating materials
2010
Organically-modified nanofiller clays can have significantly different aspect ratios as well as accumulate a relatively large amount of water in the composite bulk due to the contribution of the filler itself and the interaction between filler and polymer matrix. This paper investigates the effect of water absorption in a nanostructured thermoplastic polymer, namely ethylene-vinyl-acetate (EVA), on electrical property modifications considering the contribution of aspect ratio. The change of electrical properties (particularly space charge accumulation, electric strength, bulk conductivity and permittivity/losses) is studied as a function of water content absorbed by nanofillers having diffe…
Dielectric characterization and ionic conductivity of α-LiIO3 crystals related to the growth conditions
2000
Abstract The dielectric response of α-LiIO3 has been studied at room temperature between 20 Hz and 1 MHz with various types of electrodes and compared to the results in the literature. By changing the sample thickness, a relaxation of space charges is clearly identified and the bulk ionic conductivity is deduced from the admittance diagram. Finally a comparison is carried out between chromium doped and undoped crystals obtained from acid and neutral growth solutions.
Dielectric response of α-LiIO3 acid type crystals
1998
Abstract α-LiIO 3 is often used as non-linear optical material. In view of its preparation, low pH aqueous solutions are used as mother solutions, which give crystals with some hydrogen incorporated to the lattice. Thus, dielectric characterization appears as a very important tool. In this work, the dielectric properties of acid type α-LiIO 3 crystals (conductivity, permittivity, loss-angle tangent) are investigated as functions of temperature and frequency, through an original method allowing seemingly continuous measurements and avoiding space charge contributions to the measurements. The results show the dipolar and low frequency conductivity contributions to the dielectric response. The…