Search results for "Capacitance"

Regulation of Calcium Channel Activity by Lipid Domain Formation in Planar Lipid Bilayers

2003

The sarcoplasmic reticulum channel (ryanodine receptor) from cardiac myocytes was reconstituted into planar lipid bilayers consisting of 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) and 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) in varying ratios. The channel activity parameters, i.e., open probability and average open time and its resolved short and long components, were determined as a function of POPE mole fraction (X(PE)) at 22.4 degrees C. Interestingly, all of these parameters exhibited a narrow and pronounced peak at X(PE) approximately 0.80. Differential scanning calorimetric measurements on POPE/POPC liposomes with increasing X(PE) indicated that the lipid bilayer ente…

Super-Resolution Scanning Near-Field Optical Microscopy

2007

Scanning near-field optical microscopy (SNOM) is a method to obtain information about the optical properties of a sample at a lateral resolution below the diffraction limit of far-field microscopy. In SNOM, a light source of a dimension which is small compared to the wavelength of light and which is held at a small distance from the sample is scanned across the surface of the sample. The modulation by the sample of the light emitted from the source is recorded as a signal. As a general rule one may say that the size of the source and the distance to the sample limit the resolution of SNOM. A radiating self-emitting point dipole may be regarded as an idealized SNOM source. With such a source…

A theoretical basis for the high-frequency performance of the outer hair cell’s receptor potential

1997

The frequency response of the outer hair cell (OHC) was studied theoretically. An electrical model of the OHC was analyzed mathematically, taking into account the effect of its inherent voltage-dependent capacitance. It was found that the variations of the capacitance dependent on the membrane potential could enhance the high-frequency response of the OHC, so that its cutoff frequency could be extended into the audio range. It was found further that the enhancement of the frequency response of the OHC was strongly dependent on its resting potential and on the ratio of the maximum voltage-dependent capacitance to the membrane linear capacitance.

Mott-Schottky analysis of differential capacitance data of passive-film electrolyte junctions. Is it really providing correct physical insights on th…

2009

Energy conversion from external fluctuating signals based on asymmetric nanopores

2015

Electrical transduction from fluctuating external signals is central to energy conversion based on nanoscale electrochemical devices and bioelectronics interfaces. We demonstrate theoretically and experimentally a significant energy transduction from white noise signals using the electrical rectification of asymmetric nanopores in polymeric membranes immersed in aqueous electrolyte solutions. Load capacitor voltages of the order of 1 V are obtained within times of the order of 1 min by means of nanofluidic diodes which convert zero time-average potentials of amplitudes of the order of 1 V into average net currents. We consider single-nanopore and multipore membranes to show that the convers…

Photoswitchable Micro-Supercapacitor Based on a Diarylethene-Graphene Composite Film

2017

Stimuli-responsive micro-supercapacitors (MSCs) controlled by external stimuli can enable a wide range of applications for future on-chip energy storage. Here, we report on a photoswitchable MSC based on a diarylethene-graphene composite film. The microdevice delivers an outstanding and reversible capacitance modulation of up to 20%, demonstrating a prototype photoswitchable MSC. Terahertz spectroscopy indicates that the photoswitching of the capacitance is enabled by the reversible tuning of interfacial charge injection into diarylethene molecular orbitals, as a consequence of charge transfer at the diarylethene-graphene interface upon light modulation.

Quantum Transport and Current Distribution at Radio Frequency in Multiwall Carbon Nanotubes

2012

Multiwall carbon nanotubes represent a low-dimensional material that could serve as building blocks for future carbon-based nanoelectronics. The understanding of the electromagnetic performances at radio frequency of these materials for use in nanointerconnects is strictly related to the analysis of their transport properties as function of the working conditions. In this paper, we present an explicit expression of the conducting channels as function of diameter, temperature, doping, and supply voltage for both metallic and semiconducting carbon nanotubes. The proposed formula is based on the Dirac cone approximation of the conducting band energy of graphene nearby the Fermi points, combine…

Active snubber network design and implementation on the primary side of an isolated Ćuk converter realizing soft-switching for efficiency …

2008

This paper describes the process of improving the efficiency of an existing isolated DC/DC converter based on CUK topology with secondary side synchronous rectification, by means of the introduction of an active snubber network on the primary side. The snubber circuit reduces to zero the switching losses during the off-time interval of secondary SR. In particular, the efficiency improvement is due to the elimination of the primary MOSFET Coss output capacitance losses, and mainly of the reverse recovery losses on the secondary SR MOSFET. However, the insertion of the active snubber creates itself additional losses in the circuit, and therefore to measure the really introduced benefit it is …

The measuring method for tests of horizontal two-phase gas–liquid flows, using optical and capacitance tomography

2009

Abstract The paper presents a measurement method in testing horizontal two-phase gas–liquid flows. It also describes the test stand including two tomography measurement systems. The optical and capacitance tomography systems can be used for measurements at the same time. It is necessary to apply two tomography systems working at the same time because of complexity of phenomena occurring in two-phase flows, and a wide range of applicability of the presented method. The optical tomography system in which a tested object is illuminated from five projections. The measurement of luminous intensity is changed into a discrete signal (0 or 1) in the detectors including 64 optical sensors. Next, the…

Pressure dependence of the low-frequency dielectric constant of KNbO_3

1997

The effect of pressure on the low-frequency dielectric constant, $\epsilon_0$, of single crystals of KNbO_3 is investigated by means of capacitance measurements. The dielectric constant increases with pressure up to 22.5 kbar, where it exhibits a large value ($\epsilon_0$ = 5000), and then decreases. This change in its behaviour is related to a phase transition induced by pressure. On decompression, the samples do not revert back to the ambient pressure phase.