Optical control of the current-voltage relation in stacked superconductors

Ion-channel functions are often studied by the current-voltage relation, which is commonly fitted by the Boltzmann equation, a powerful model widely used nowadays. However, the Boltzmann model is restricted to a two-state ion-permeation process. Here we present an improved model that comprises a flexible number of states and incorporates both the single-channel conductance and the open-channel probability. Employing the channel properties derived from the single-channel recording experiments, the proposed model is able to describe various current-voltage relations, especially the reversal ion-permeation curves showing the inward- and outward-rectifications. We demonstrate the applicability of the proposed model using the published patch-clamp data of BK and MthK potassium channels, and discuss the similarity of the two channels based on the model studies.

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Nucleotide receptors activate cation, potassium, and chloride currents in a liver cell line

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1994.266.4.g544 ◽

1994 ◽

Vol 266 (4) ◽

pp. G544-G553 ◽

Cited By ~ 7

Author(s):

J. G. Fitz ◽

A. H. Sostman

Keyword(s):

Nucleotide Receptors ◽

Chloride Currents ◽

Whole Cell Patch Clamp ◽

Current Voltage ◽

Htc Cells ◽

Sequential Activation ◽

Initial Activation ◽

K Permeability ◽

Current Voltage Relation ◽

Sustained Activation

By use of whole cell patch-clamp techniques, the effects of extracellular ATP on membrane ion currents of HTC cells from a rat liver tumor line were evaluated. ATP (500 microM) or the nonhydrolyzable analogue adenosine 5'-O-(3-thiotriphosphate) caused sequential activation of three currents: Icat (-1,325 +/- 255 pA at -80 mV) occurred early, was due to increased Na+ and K+ permeability, was present in 56% of 64 consecutive cells, and rapidly inactivated; IK (274 +/- 45 pA at 0 mV) was present in 59% of cells and also inactivated; and ICl (1,172 +/- 237 pA at +60 mV) was present in 94% of studies, was sustained, and exhibited outward rectification of the current-voltage relation. All three currents were present in 39% of cells. Increasing intracellular Ca2+ concentration ([Ca2+]i) by exposure to the 5'-nucleotide receptor agonist UTP (500 microM) or to thapsigargin activated Icat and IK but not ICl, whereas increasing ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid in the pipette (> or = 5 mM) inhibited ATP-dependent activation of Icat and IK but not ICl. A P2x-preferring agonist alpha, beta-methylene ATP (500 microM) did not activate currents; a P2y-preferring agonist 2-methylthioadenosine triphosphate activated Icat and IK at concentrations of 500 microM but not 50 microM. In perforated patch recordings, ATP produced triphasic changes in membrane potential with initial depolarization due to Icat, subsequent hyperpolarization due to IK, and a later sustained depolarization due to ICl. These findings indicate that ATP modulates HTC cell ion permeability through initial activation of Icat and IK mediated by 5'-nucleotide receptors which mobilize [Ca2+], and sustained activation of ICl through a separate Ca(2+)-independent mechanism.

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Current-voltage relation for abrupt N+-P-N+ and N-i-N structures

Solid-State Electronics ◽

10.1016/0038-1101(92)90316-5 ◽

1992 ◽

Vol 35 (7) ◽

pp. 897-904 ◽

Cited By ~ 2

Author(s):

J.G.C. Bakker ◽

J. Bisschop ◽

W.H.A. Schilders

Keyword(s):

Current Voltage ◽

Current Voltage Relation

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A linear auroral current-voltage relation in fluid theory

Annales Geophysicae ◽

10.5194/angeo-22-1719-2004 ◽

2004 ◽

Vol 22 (5) ◽

pp. 1719-1728 ◽

Cited By ~ 11

Author(s):

J. Vedin ◽

K. Rönnmark

Keyword(s):

Kinetic Model ◽

Large Scale ◽

Equations Of State ◽

Potential Drop ◽

Fluid Models ◽

Linear Current ◽

Current Voltage ◽

Auroral Phenomena ◽

Auroral Current ◽

Current Voltage Relation

Abstract. Progress in our understanding of auroral currents and auroral electron acceleration has for decades been hampered by an apparent incompatibility between kinetic and fluid models of the physics involved. A well established kinetic model predicts that steady upward field-aligned currents should be linearly related to the potential drop along the field line, but collisionless fluid models that reproduce this linear current-voltage relation have not been found. Using temperatures calculated from the kinetic model in the presence of an upward auroral current, we construct here approximants for the parallel and perpendicular temperatures. Although our model is rather simplified, we find that the fluid equations predict a realistic large-scale parallel electric field and a linear current-voltage relation when these approximants are employed as nonlocal equations of state. This suggests that the concepts we introduce can be applied to the development of accurate equations of state for fluid simulations of auroral flux tubes.Key words. Magnetospheric physics (auroral phenomena; magnetosphere-ionosphere interactions) – Space plasma physics (kinetic and MHD theory)

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Slow inward current may produce many results attributed to IX1 in cardiac Purkinje fibers

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1985.249.1.h122 ◽

1985 ◽

Vol 249 (1) ◽

pp. H122-H132

Author(s):

J. M. Jaeger ◽

W. R. Gibbons

Keyword(s):

Action Potential ◽

Outward Current ◽

Purkinje Fiber ◽

Slow Inward Current ◽

Channel Blockers ◽

Inward Current ◽

Purkinje Fibers ◽

Cardiac Purkinje Fibers ◽

Current Voltage ◽

Current Voltage Relation

We have tried to answer two fundamental questions concerning the outward current IX1 of cardiac Purkinje fibers. 1) Is it possible that current changes identified as arising from IX1 in voltage-clamp experiments are actually manifestations of changes in the slow inward current (Isi); and 2) is IX1 in fact required to produce the electrical phenomena attributed to it? Isi behavior and the role of IX1 were explored using computer simulation. The Isi model produced current changes during depolarizations and hyperpolarizations from depolarized resting potentials like those attributed to IX1. It also produced a component of "tail currents" that behaved like IX1. If these current changes were analyzed, assuming that an outward current is responsible, the resulting kinetics and current voltage relation would be very similar to the kinetics and current voltage relation reported for IX1. Using the McAllister, Noble, and Tsien formulation of the Purkinje fiber action potential, we found that IX1 is not essential for repolarization of the reconstructed action potential nor is it needed to reproduce interval duration effects and the effects of applied current in that model. Data suggesting that calcium channel blockers reduce IX1 and that catecholamines increase IX1 may be explained as arising from changes in Isi. Thus many manifestations of IX1 can be explained as arising from unanticipated behavior of Isi, and IX1 does not necessarily play a key role in generating Purkinje fiber electrical activity.

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Effects of Magnetic Fields on PN Junctions in Piezomagnetic–Piezoelectric Semiconductor Composite Fibers

International Journal of Applied Mechanics ◽

10.1142/s1758825120500854 ◽

2020 ◽

Vol 12 (08) ◽

pp. 2050085

Author(s):

Chao Liang ◽

Chunli Zhang ◽

Weiqiu Chen ◽

Jiashi Yang

Keyword(s):

Magnetic Field ◽

Composite Fiber ◽

Transverse Magnetic ◽

Piezoelectric Semiconductor ◽

One Dimensional ◽

Current Voltage ◽

Potential Applications ◽

Multiferroic Composite ◽

The Magnetic Field ◽

Current Voltage Relation

We study the electromechanical and electrical behaviors of a PN junction in a multiferroic composite fiber, consisting of a piezoelectric semiconductor (PS) layer between two piezomagnetic (PM) layers, under a transverse magnetic field. Based on the derived one-dimensional model for multiferroic composite semiconductor structures, we obtain the linear analytical solution for the built-in potential and electric field in the junction when there is no applied voltage between the two ends of the fiber. When a bias voltage is applied over the two ends of the fiber, a nonlinear numerical analysis is performed for the current–voltage relation. Both a homogeneous junction with a uniform PS layer and a heterogeneous junction with two different PSs on different sides of the junctions are studied. It is found that overall the homogeneous junction is essentially unaffected by the magnetic field, and the heterojunction is sensitive to the magnetic field with potential applications in piezotronics.

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Genetic-based optimization of a multi insulator tunneling diode for THz energy harvesting

Wireless Power Transfer ◽

10.1017/wpt.2020.8 ◽

2020 ◽

Vol 7 (1) ◽

pp. 60-64

Author(s):

Mazen Shanawani ◽

Diego Masotti ◽

Alessandra Costanzo

Keyword(s):

Energy Harvesting ◽

Physical Parameters ◽

Dynamic Resistance ◽

Figures Of Merit ◽

Tunneling Diodes ◽

Optimization Framework ◽

Tunneling Diode ◽

Current Voltage ◽

The Impact ◽

Current Voltage Relation

AbstractThe deployment of multi-insulator tunneling diodes has recently had more attention to be used as rectifiers in energy harvesting rectennas with good potentiality for a millimeter and terahertz range. However, with the rather complicated math to obtain the current–voltage relation, it is difficult to evaluate the design figures of merit (FOM)s such as asymmetry, nonlinearity, responsivity, and dynamic resistance and monitor the impact of changing physical parameters on them. This complicates the decision-making process for the required physical parameters. In this work, a heuristic optimization framework using genetic algorithm is suggested using the transfer matrix method to find the combination of physical parameters which satisfies the minimum required FOM set by users and weighted by their preference.

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A patch-clamp study: secretagogue-induced currents in rat peritoneal mast cells

AJP Cell Physiology ◽

10.1152/ajpcell.1989.256.3.c560 ◽

1989 ◽

Vol 256 (3) ◽

pp. C560-C568 ◽

Cited By ~ 47

Author(s):

M. Kuno ◽

T. Okada ◽

T. Shibata

Keyword(s):

Mast Cells ◽

Patch Clamp ◽

Reversal Potential ◽

Whole Cell ◽

Current Voltage ◽

Peritoneal Mast Cells ◽

Induced Currents ◽

Rat Peritoneal Mast Cells ◽

Whole Cell Recordings ◽

Current Voltage Relation

Ca2+ entry through plasma membrane has been considered to play a significant role in elevating cytosolic free Ca2+ concentrations during stimulus-secretion coupling in mast cells, but electrophysiological evidence of the Ca2+ channels is lacking. We examined the properties of secretagogue (compound 48/80)-induced currents in rat peritoneal mast cells, using the patch-clamp technique. In the whole cell recordings, the addition of compound 48/80 induced transient currents that were suppressed by Cd or reduced by ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). In Ringer solution containing 2 mM Ca2+, the current-voltage relation was fairly linear from -100 to 50 mV and the reversal potential was 14 +/- 10.1 mV (n = 9). When the external Ca2+ was approximately 1 microM, the compound 48/80-induced currents were marginal, but readmission of Ca2+ or Ba2+ to the bath solution led to an appearance of the currents. In the cell-attached patches, the stimulation enhanced the activity of inward current mediated by Ba2+. The unitary inward Ba2+ current was characterized by the unitary conductance of 10.5 +/- 2.0 pS (n = 10) with isotonic BaCl2 pipette solution, the extrapolated reversal potential of 60.7 +/- 16.0 mV (n = 10) positive to the resting membrane potentials. The percent open time of the inward Ba2+ current channel was not appreciably changed by voltage. In some whole cell recordings, an increase in openings of the cation-selective channel (20-45 pS) was identified in the stimulated cells. When the external Na+ was completely replaced by choline+, the compound 48/80-induced currents had a fairly linear current-voltage relation.(ABSTRACT TRUNCATED AT 250 WORDS)

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Block of the cyclic GMP-gated channel of vertebrate rod and cone photoreceptors by l-cis-diltiazem.

The Journal of General Physiology ◽

10.1085/jgp.100.5.783 ◽

1992 ◽

Vol 100 (5) ◽

pp. 783-801 ◽

Cited By ~ 111

Author(s):

L W Haynes

Keyword(s):

Binding Site ◽

Single Molecule ◽

Single Channel ◽

Inward Rectification ◽

Pipette Solution ◽

Current Voltage ◽

Voltage Dependent ◽

Extracellular Side ◽

Current Voltage Relation ◽

Cytoplasmic Side

Inside-out patches were excised from catfish rod or cone outer segments. Single channel and macroscopic currents were recorded from GMP-gated channels activated by 1 mM cGMP in low divalent buffered saline. Currents were blocked by the application of micromolar concentrations of l-cis-diltiazem to the cytoplasmic side of the patch. The concentration dependence of block indicated that a single molecule was sufficient to block a channel and that all channels were susceptible to block. The dissociation constant for the rod channel was an order of magnitude smaller than for the cone channel, but the voltage dependence of block was nearly identical. The macroscopic current-voltage relation in the presence of blocker was inwardly rectifying and superficially resembled voltage-dependent block by an impermeant blocker occluding the ion-conducting pore of the channel. Block by diltiazem acting from the extracellular side of the channel was investigated by including 5 microM diltiazem in the recording pipette solution. The macroscopic current-voltage relation again showed inward rectification, inconsistent with the idea that diltiazem acts by occluding the pore at the external side. The kinetics of block by diltiazem applied to the intra- and extracellular side were measured in cone patches containing only a single channel. The unbinding rates were similar in both cases, suggesting a single binding site. Differences in the binding rate were consistent with greater accessibility to the binding site from the cytoplasmic side. Block from the cytoplasmic side was independent of pH, suggesting that the state of ionization of diltiazem was not related to its ability to block the channel in a voltage-dependent fashion. These observations are inconsistent with a pore-occluding blocker, but could be explained if the hydrophobic portion of diltiazem partitioned into the hydrophobic core of the channel protein, perhaps altering the gating of the channel.

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