Conductance

About: Conductance is a research topic. Over the lifetime, 8088 publications have been published within this topic receiving 235961 citations.

Selectively dopedn-AlxGa1−xAs/GaAs heterostructures with high-mobility two-dimensional electron gas for field effect transistors

Abstract: In selectively dopedn-AlxGa1−xAs/GaAs heterostructures with high-mobility two-dimensional electron gas (2 DEG) at the heterointerface a second conductive channel exists, if the AlxGa1−xAs layer is not totally depleted from free carries. The occurrence of parallel conductance has a deleterious effect on the performance of high-electron mobility transistors (HEMTs) fabricated from this material. Although in principle computable, parallel conductance depends on a large number of design parameters to be chosen for the heterostructure, which are additionally affected by the presence of deep electron traps inn-AlxGa1−xAs of composition 0.25

Control of the amiloride-sensitive Na+ current in mouse salivary ducts by intracellular anions is mediated by a G protein.

Abstract: 1. We have previously reported that the Na+ conductance in mouse intralobular salivary duct cells is controlled by cytosolic anions, being inhibited by high cytosolic concentrations of Cl- and NO3- but not of glutamate. In the present paper, we use whole-cell patch-clamp methods to investigate whether this anion effect is mediated by a G protein. 2. Inclusion of 100 mumol l-1 GTP-gamma-S, a non-hydrolysable GTP analogue, in the glutamate-containing pipette solution, i.e. when the Na+ conductance is active, reduced the size of the Na+ conductance whereas inclusion of 100 mumol l-1 GDP-beta-S, a non-hydrolysable GDP analogue, had no effect. 3. Inclusion of 100 mumol l-1 GDP-beta-S in the NO3(-)-containing pipette solution, i.e. when the Na+ conductance is inhibited, reactivated the conductance. Inclusion of 500 ng ml-1 activated pertussis toxin in the NO3(-)-containing pipette solution had a similar effect on the Na+ conductance. 4. We conclude that the inhibitory effect of intracellular anions such as NO3- and Cl- on the amiloride-sensitive Na+ conductance in mouse mandibular intralobular duct cells is mediated by a G protein sensitive to pertussis toxin.

Highly Reproducible and Regulated Conductance Quantization in a Polymer‐Based Atomic Switch

Abstract: A detailed understanding of the conductance quantization and resistive switching phenomena in redox-based memories is crucial for realizing atomic-scale memory devices and for finding the adequate design principles on which they can be based. Here, the emergence of quantized conductance states and their correlation with resistive switching characteristics in polymer-based atomic switches are investigated using combinations of current–voltage measurements and first-principles density functional theory (DFT) simulations. Various conductance states, including integer and half-integer multiples of a single atomic point contact and fractional conductance variations, are observed in an Ag/polyethylene oxide/Pt device under sweeping of bias voltage. Moreover, highly controllable and reproducible quantized conductance behaviors by tuning the voltage sweep rate and the sweep voltage range, suggesting well-controlled formation of the atomic point contact, are demonstrated. The device also exhibits longer retention times for higher conductance states. The DFT simulations reveal the transmission eigenstate of geometrically optimized atomic point contact structures and the impact of the atomic configurations and structural stability on the conductance state, which also explains their resistive switching behaviors. The well-defined, multiple quantized conductance states observed in these polymer-based atomic switches show promise for the development of new multilevel memory devices.

Effect of K+ channels in the apical plasma membrane on epithelial secretion based on secondary active Cl- transport.

Abstract: Models of epithelial salt secretion, involving secondary active transport of Cl- [9], locate the K+ conductance of the plasma membrane exclusively in the basolateral membrane, although there is considerable experimental evidence to show that many secretory epithelia do have a significant apical K+ conductance. We have used an equivalent circuit model to examine the effect of an apical K+ conductance on the composition and flow rate of the fluid secreted by an epithelium in which secretion is driven by the secondary active transport of Cl-. The parameters of the model were chosen to be similar to those measured in the dog tracheal mucosa when stimulated with adrenaline to secrete. We find that placing a K+ conductance in the apical membrane can actually enhance secretion provided the proportion of the total cell K+ conductance in the apical membrane is not greater than about 60%, the enabling effect on secretion being maximal when the proportion is around 10-20%. We also find that even when the entire cell K+ conductance is located in the apical membrane, the secreted fluid remains relatively Na+ rich. Analysis of the sensitivity of model behavior to the choice of values for the parameters shows that the effects of an apical K+ conductance are enhanced by increasing the ratio of the paracellular resistance to the transcellular resistance.

The conductance of cyclic polyether-cation complexes

Abstract: Precise conductance measurements are reported for sodium, potassium, and cesium salts in methanol and acetonitrile solutions containing cyclic polyethers dibenzo-18-crown-6 and dicyclohexyl-18-crown-6. Decreases in equivalent conductance caused by the addition of a cyclic polyether to solutions of constant ionic strength were analyzed by nonlinear least squares to give association constants and equivalent conductances of the cation-polyether complex. The selectivity observed for the complexing is a function not only of ionic size but also of solvent.