Search results for "VOLTAGE"
showing 10 items of 934 documents
Membrane potential bistability in nonexcitable cells as described by inward and outward voltage-gated ion channels.
2014
The membrane potential of nonexcitable cells, defined as the electrical potential difference between the cell cytoplasm and the extracellular environment when the current is zero, is controlled by the individual electrical conductance of different ion channels. In particular, inward- and outward-rectifying voltage-gated channels are crucial for cell hyperpolarization/depolarization processes, being amenable to direct physical study. High (in absolute value) negative membrane potentials are characteristic of terminally differentiated cells, while low membrane potentials are found in relatively depolarized, more plastic cells (e.g., stem, embryonic, and cancer cells). We study theoretically t…
Adsorption of functionalized biomembrane vesicles on crystalline surfaces monitored by FTIR- and Surface Enhanced FTIR Spectroscopy
1997
A special class of integral membrane proteins are the ion channels. To use them for technical purposes they have to be transferred with their lipid surrounding onto artificial materials, i.e. crystals. In this study we used vesicles containing the nicotinic acetylcholine receptor (nAChR) and porin. The first allows the ligand gated flow and the second allows the voltage gated flow of cations across the membrane. We used ATR-FTIR spectroscopy and surface enhanced FTIR techniques (SEIRA) to monitor the direct contact of the vesicles with the crystal.
Development of a module of stacks of air-breathing microbial fuel cells to light-up a strip of LEDs
2018
Abstract This work focuses on scaling-up of the microbial fuel cells technology according to the principle of miniaturization and multiplication. Seven stacks of 16 mini-MFCs (electrodic area of 0.866 cm2) were built up leading to a big module of 112 MFCs. The electrical connection among the MFCs in the stacks and among the stacks into the modules was optimized in order to implement this technology. Results show that 1 MFC generates 1.22 mW while the optimization of the electric connection in order to achieve the maximum power results in 6.62 mW compared to the theoretical 182 mW, indicating the existence of large energy losses in the system. However, to light a LED there is not a threshold…
On the staking of miniaturized air-breathing microbial fuel cells
2018
Abstract This work focuses on the scale-up of the MFCs by miniaturization and multiplication strategy. Performances of five stacks containing 1, 2, 5, 8 and 16 MFCs were compared. Each stack was evaluated under individual, parallel and series electrical connection as well as for cascade or individual hydraulic connection. Cascade feeding mode with a tank per stack favours the COD removal when the number of MFCs in the stack increases. However, despite operating without COD limitations, the energy production was disadvantaged. By changing the feeding system of a tank per stack into an individual tank per MFC, the performance of the whole stack enhances considerably. Stacking in series can in…
Electrical Pumping of Potassium Ions Against an External Concentration Gradient in a Biological Ion Channel
2013
We show experimentally and theoretically that significant currents can be obtained with a biological ion channel, the OmpF porin of Escherichia coli, using zero-average potentials as driving forces. The channel rectifying properties can be used to pump potassium ions against an external concentration gradient under asymmetric pH conditions. The results are discussed in terms of the ionic selectivity and rectification ratio of the channel. The physical concepts involved may be applied to separation processes with synthetic nanopores and to bioelectrical phenomena. (C) 2013 AIP Publishing LLC.
Flux-flow instability and heating effects in Bi2Sr2CaCu2O8 and YBa2Cu3O7 thin films
2000
Abstract We investigated current–voltage curves of Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 thin films. Voltage jumps due to flux-flow instabilities at high vortex-velocities were found and interpreted in the framework of the theory of Larkin and Ovchinnikov. The extensions introduced by Bezuglyj et al. account for quasiparticle heating during the measurement. While in Bi 2 Sr 2 CaCu 2 O 8 the instability is found in the vortex-liquid phase, in YBa 2 Cu 3 O 7 we observed it in the vortex-glass phase. Moreover, we studied the temporal behavior of the instability in current–voltage curves with a time resolution in the microsecond range.
Lack of GDAP1 induces neuronal calcium and mitochondrial defects in a knockout mouse model of Charcot-Marie-tooth neuropathy
2015
27 páginas, 9 figuras.
Safety Assurance of a High Voltage Controller for an Industrial Robotic System
2020
Abstract Due to the risk of discharge sparks and ignition, there are strict rules concerning the safety of high voltage electrostatic systems used in industrial painting robots. In order to assure that the system fulfils its safety requirements, formal verification is an important tool to supplement traditional testing and quality assurance procedures. The work in this paper presents formal verification of the most important safety functions of a high voltage controller. The controller has been modelled as a finite state machine, which was formally verified using two different model checking software tools; Simulink Design Verifier and RoboTool. Five safety critical properties were specifie…
Voltage Source Multilevel Inverters With Reduced Device Count: Topological Review and Novel Comparative Factors
2021
Multilevel inverters (MLIs) have gained increasing interest for advanced energy-conversion systems due to their features of high-quality produced waveforms, modularity, transformerless operation, voltage, and current scalability, and fault-tolerant operation. However, these merits usually come with the cost of a high number of components. Over the past few years, proposing new MLIs with a lower component count has been one of the most active topics in power electronics. The first aim of this article is to update and summarize the recently developed multilevel topologies with a reduced component count, based on their advantages, disadvantages, construction, and specific applications. Within …
New Multilevel Inverter Topology with Reduced Component Count
2019
This paper introduces a new topology of modular multilevel inverters, being suitable in medium and high voltage applications. As compared to the existing circuits, the proposed topology has advantages of high ‘levels/components’ ratio, increasing the output voltage levels without increasing the voltage stress across the used switches, structure simplicity, isolation features, and modularity. These merits allow it to fit well in high-reliability medium-power applications, which require fast troubleshooting and maintenance flexibility. Operating principles of the proposed scheme are detailed in low frequency and pulse width modulation. Simulation and experimental results validate the effectiv…