Search results for "Voltage"
showing 10 items of 934 documents
The influence of Ca2+ antagonists on the ciliary activity of the guinea pig trachea.
1990
The ciliary activity of the guinea pig tracheal respiratory epithelium was measured using a photoelectric device. Fourteen animals were administered 75 mg diltiazem/kg body weight 2 days, 1 day and 4 h prior to the investigation. Thirteen animals served as controls. In the pretreated group, the mean ciliary stroke frequency (13.4 +/- 3.0 Hz) was significantly lower (P = 0.02) than in the control group (16.6 +/- 3.7 Hz). The application of aerosolized 0.3 mmol/l nifedipine solution on the tracheal preparations of the control animals also significantly reduced the stroke frequency (P = 0.02). The ciliary activity never dropped beyond a frequency of about 8 Hz. The most probable interpretation…
Differential blockade by nifedipine and ω-conotoxin GVIA of α1- and β1-adrenoceptor-controlled calcium channels on motor nerve terminals of the rat
1990
Electrically evoked release of [3H]acetylcholine ([3H]ACh) from the rat phrenic nerve and its facilitation by stimulation of presynaptic alpha 1- and beta 1-adrenoceptors were investigated in the absence and presence of nifedipine and omega-conotoxin GVIA. Both calcium channel antagonists did not modify electrically evoked [3H]ACh release, but selectively blocked the effect triggered by both facilitatory adrenergic receptors. The increase in [3H]ACh release mediated via beta 1-adrenoceptor activation was abolished by low concentrations (1 nM) of omega-conotoxin GVIA, whereas nifedipine (100 nM) abolished the facilitatory effect mediated via alpha 1-adrenoceptor stimulation. Therefore, the b…
MECHANISMS OF TENSION DEVELOPMENT INDUCED BY MONENSIN IN GUINEA-PIG AORTA : EFFECTS OF VERAPAMIL, OUABAIN, PRAZOSIN AND GLIBENCLAMIDE
1993
The influence of monensin (10 µmol/L) alone and in the presence of verapamil (3 µmol/L) or ouabain (1 mmol) and prazosin (1 µmol/L) or glibenclamide (10 µmol/L) were studied on the muscle tension of guinea pig aorta. Changes in tissue sodium, potassium and calcium ion contents of the aortic muscle produced by monensin in the presence of prazosin were evaluated. Monensin in normal Tyrode's solution containing prazosin caused an increase in the resting tension followed by a decrease and returned to normal values. Verapamil reduced the muscle tension induced by monensin. After ouabain, monensin induced sustained increase in the resting tension. Glibenclamide partially reversed the relaxant pha…
Endothelin action on goat cerebral arteries.
1990
Abstract Cumulative application of endothelin-1 (human) markedly constricted goat isolated cerebral arteries in a concentration-dependent manner. Contractile responses were not affected by removal of endothelial cells. Removal of extracellular calcium or addition of the calcium channel blocker nicardipine (10−7 M) failed to abolish responses to endothelin. The results suggest that the endothelium-independent constriction of cerebral arteries produced by endothelin cannot be explained solely by voltage-dependent calcium channels. The contractile responses are likely to be mediated by stimulation of specific receptors for this peptide.
A Cost-Effective Solution for Clearing High-Impedance Ground Faults in Overhead Low-Voltage Lines
2019
Downed distribution conductors in overhead distribution systems may not be a concern for equipment but greatly challenge the safety of persons, as well as the integrity of properties. Standard overcurrent protective devices may not be able to detect the magnitudes of currents resulting from high-impedance ground faults. Sophisticated relays able to detect high-impedance ground faults have been available to electric utilities. However, their implementation is rather uncommon, especially in developing countries, most likely due to their costs. In this paper, the authors formalize the problem, and propose a possible cost-effective solution for low-voltage overhead lines with neutral wire. This…
Single Event Transients and Pulse Quenching Effects in Bandgap Reference Topologies for Space Applications
2016
An architectural performance comparison of bandgap voltage reference variants, designed in a $0.18~\mu \text {m}$ CMOS process, is performed with respect to single event transients. These are commonly induced in microelectronics in the space radiation environment. Heavy ion tests (Silicon, Krypton, Xenon) are used to explore the analog single-event transients and have revealed pulse quenching mechanisms in analogue circuits. The different topologies are compared, in terms of cross-section, pulse duration and pulse amplitude. The measured results, and the explanations behind the findings, reveal important guidelines for designing analog integrated circuits, which are intended for space appli…
Min-Type Control Strategy of a DC-DC Synchronous Boost Converter
2019
International audience; This paper presents the analysis and design of a min-type strategy to control a synchronous boost converter in continuous conduction mode. The strategy uses a nonlinear switching surface to establish the change of topology in the converter and is analyzed by means of a sliding-mode control approach. Subsequently, the min-type strategy is modified by a hybrid control formulation, which introduces a hysteresis width and a dwell-time to obtain a finite switching frequency in the start-up and steady-state respectively. The hybrid control formulation is implemented digitally by means of a microprocessor which processes the samples of inductor current and capacitor voltage…
Technical and economical comparison between NdFeB and hard ferrites linear electrical generators from sea waves
2015
In this paper the authors perform a technical-economic comparison of two different Tubular Permanent Magnet Linear Machines for sea waves generation by using finite elements analysis. The first configuration includes ferrite rings while the second configuration includes neodymium-iron-boron rings. In order to compare the two types in economic and technical terms, a detailed analysis of the main figures of merit of the two configurations has been carried out. In particular, significant data such as flux distribution, rated voltage and current, axial force, electric power, realization cost and maintenance cost have been compared.
Generalized Noise Study of Solid-State Nanopores at Low Frequencies.
2017
Nanopore technology has been extensively investigated for analysis of biomolecules, and a success story in this field concerns DNA sequencing using a nanopore chip featuring an array of hundreds of biological nanopores (BioNs). Solid-state nanopores (SSNs) have been explored to attain longer lifetime and higher integration density than what BioNs can offer, but SSNs are generally considered to generate higher noise whose origin remains to be confirmed. Here, we systematically study low-frequency (including thermal and flicker) noise characteristics of SSNs measuring 7 to 200 nm in diameter drilled through a 20-nm-thick SiNx membrane by focused ion milling. Both bulk and surface ionic curren…
The Relation between Photoconductivity Threshold and Open-Circuit Voltage in Organic Solar Cells
2022
Financial support provided by Scientific Research Project for Students and Young Researchers No. SJZ/2020/08 implemented at the Institute of Solid State Physics, University of Latvia is greatly acknowledged. Institute of Solid State Physics, University of Latvia as the Centre of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART².