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Abstract High voltage direct current (HVDC) systems are efficient solutions for the integration of large-scale renewable energy sources with the main power grids. The rapid development of the HVDC grid has resulted in a growing interest in DC circuit breakers (DCCBs). A fast and reliable circuit breaker is a necessary requirement in the development of large scale HVDC grids. This paper provides a comprehensive review and survey of the HVDC CBs and discusses potential research directions. Operational principles and the main features of various DCCBs are described and their merits and shortcomings are also highlighted.

High voltage direct current (HVDC) systems are efficient solutions for the integration of large-scale renewable energy sources with the main power grids. The rapid development of the HVDC grid has resulted in a growing interest in DC circuit breakers (DCCBs). A fast and reliable circuit breaker is a necessary requirement in the development of large scale HVDC grids. This paper provides a comprehensive review and survey of the HVDC CBs and discusses potential research directions. Operational principles and the main features of various DCCBs are described and their merits and shortcomings are also highlighted. [ABSTRACT FROM AUTHOR]

Computing-in-memory (CIM) is currently the most promising approach to break through the limitations of the memory wall and improve the energy efficiency of edge processors. In truth, CIM faces plenty of design challenges such as read corruption, accumulative non-linearity, multi-bit data operations, area and energy efficiency. We investigate a 3.975 Kb CIM SRAM macro that enables highly linear and full-precision multiply-and-accumulate operations in the current domain. Its array consists of XOR-10T bitcells which decouple read, write and computing. Owing to read through the gate, its read static noise margin is greatly boosted and the leakage is lessened. We also present a current mirror and voltage clamping cell to solve the voltage headroom matter for current accumulation. The accumulative current error rate resulting from leakage and process and supply is within ±0.4%. Finally, under the pulse frequency modulation technique, a time-to-digital converter with a compact area of 77.08 μ m 2 is used to complete an excellent linearity conversion. Simulation results support that the macro achieves a MAC frequency of 125 MHz at 0.9 V. The normalized energy efficiency is 18.24 TOPS/W × bit , and the throughput is 144 GOPS. Besides, we verify it can realize 96.19% accuracy on the MNIST dataset. • The proposed XOR-10T bitcell enables the single-bit multiplication operation and decouples read, write and computing. Utilizing the gate readout greatly boosts its read static noise margin and leaks less current contributing to high linearity calculations. • A current mirror and voltage clamp cell is proposed to resolve the difficulty of limited signal margin from the root. The accumulative current simulation results strongly coincide with the fitting line, with an adjusted R-squared of 1. • We introduce a TDC on the basis of the pulse frequency modulation technique to raise the operating frequency. Its area overhead is diminished by 3.4 × to 18.76 × compared to most advanced TDC and ADC designs. • The XOR-10T CIM SRAM macro achieves a fast MAC frequency of 125 MHz, a large throughput of 144 GOPS and a recognition accuracy of 96.19% on the MNIST dataset. [ABSTRACT FROM AUTHOR]

Solid-state power controllers (SSPCs) have been received increasing attention as they can configure the electrical system and protect the system by fast tripping mechanism at the same time. Although the high-voltage direct current (HVDC) electrical system can bring sustainable savings on the cables’ weight and losses, the protection can be considerably challenging. SSPCs have been successfully utilized for 28V DC aircraft onboard network. However, high-voltage ones are impeded by the vast over-voltage and the excessive losses generated from SSPC switching. This paper tries to fill this gap and presents the development of high-power SSPCs for a ±270VDC network of a future turboprop aircraft. Comprehensive designs of proper over-voltage suppression along with SSPC thermal management are presented in this paper. Besides, a comparative study on the SSPC device is carried out. Two prototypes, including a single MOSFET module and paralleling several discrete MOSFET devices, are built and then tested in the experiment. It has been validated that the proposed voltage clamping design cannot only effectively suppress the over-voltage, but also limit the SSPC temperature increase during switching for both candidates. After comparing the conduction losses, maximum junction temperature, power density, weight and volume, the single device solution is recommended as a preferable SSPC option for future aircraft.

In this article, we present a new type of Z-source inverter (ZSI) that replaces two inductors in the original quasi-ZSI with two transformers. It can produce a very high output voltage with the high value of the modulation index. Moreover, it enables both to provide a better power quality of output and to reduce the switching loss. In particular, the proposed quasi-clamped ZSI with two transformers give a unique solution to obtain high gain by reducing the turns ratio, rather than increasing it. Also, the leakage inductance of the transformer might cause huge voltage spikes across the inverter bridge. To deal with this problem, an effective clamping technique is proposed. As a result, this increases the overall efficiency of the system by utilizing the low-power switching devices. The characteristics of the proposed quasi-clamped ZSI with two transformers are comprehensively discussed with the detailed theoretical analysis. Thereafter, its performances are evaluated by both simulation and experimental tests. [ABSTRACT FROM AUTHOR]

This study mainly develops a high-efficiency single-input triple-outputs dc/dc converter (HSTDC) with a soft-switching technique for high step-up applications. In general, multiple output voltages with only one single input power source is always required for the applications of renewable energy or electric vehicles. At the high step-up operation, the proposed HSTDC has a high voltage conversion ratio to sustain the high-voltage dc bus for the utilization of dc/ac inverter. The proposed HSTDC uses a coupled inductor with lower turn ratios to achieve the high step-up voltage gain and adopts an auxiliary inductor to adjust the voltage of the auxiliary output terminal indirectly. Moreover, the utilization of voltage clamping and zero-current switching (ZCS) in the proposed HSTDC is helpful for accomplishing the goal of high-efficiency power conversion and three output voltage levels. In addition, the effectiveness of the proposed HSTDC is verified by rich experimental results.

Although conventional electromechanical circuit breakers have a proven record as effective and reliable devices for circuit protection, emerging power distribution technologies and architectures, such as dc microgrids, require improved interruption performance characteristics (e.g., faster switching speed). The need for faster switching operation, in combination with the latest developments of advanced power semiconductor technologies, has spurred an increase in the research and development in the area of solid-state circuit breakers. This article provides a comprehensive review of various solid-state circuit breaker technologies that have been reported in the literature during recent years. First, we categorize solid-state circuit breakers based on key features and subsystems, including power semiconductor devices, main circuit topologies, voltage clamping methods, gate drivers, fault detection methods, and commutation methods for power semiconductor devices. Second, we discuss the various challenges associated with the design of solid-state circuit breakers from the perspective of generic applications and provide a comparison of several solid-state breaker technologies based on key metrics. Finally, we provide a useful framework and point of reference for future development of solid-state circuit breakers for many emerging power distribution applications. [ABSTRACT FROM AUTHOR]

Transepithelial K+ absorption requires apical K+ uptake and basolateral K+ exit. In the colon, apical H+-K+-ATPase mediates cellular K+ uptake, and it has been suggested that electroneutral basolateral K+ exit reflects K+-Cl- cotransporter-1 (KCC1) operating in parallel with K+ and Cl- channels. The present study was designed to identify basolateral transporter(s) responsible for K+ exit in rat distal colon. Active K+ absorption was determined by measuring 86Rb+ (K+ surrogate) fluxes across colonic epithelia under voltage-clamp conditions. With zero Cl- in the mucosal solution, net K+ absorption was reduced by 38%, indicating that K+ absorption was partially Cl--dependent. Serosal addition of DIOA (KCC1 inhibitor) or Ba2+ (nonspecific K+ channel blocker) inhibited net K+ absorption by 21% or 61%, respectively, suggesting that both KCC1 and K+ channels contribute to basolateral K+ exit. Clotrimazole and TRAM34 (IK channel blockers) added serosally inhibited net K+ absorption, pointing to the involvement of IK channels in basolateral K+ exit. GaTx2 (CLC2 blocker) added serosally also inhibited net K+ absorption, suggesting that CLC2-mediated Cl- exit accompanies IK channel-mediated K+ exit across the basolateral membrane. Net K+ absorption was not inhibited by serosal addition of either IbTX (BK channel blocker), apamin (SK channel blocker), chromanol 293B (KV7 channel blocker), or CFTRinh172 (CFTR blocker). Immunofluorescence studies confirmed basolateral membrane colocalization of CLC2-like proteins and Na+-K+-ATPase a-subunits. We conclude that active K+ absorption in rat distal colon involves electroneutral basolateral K+ exit, which may reflect IK and CLC2 channels operating in parallel. [ABSTRACT FROM AUTHOR]

Durability and reliability are still major challenges of vehicular polymer electrolyte membrane fuel cell (PEMFC) systems. With exhaust gas recirculation on both the anode and cathode sides, two important functions can be achieved: the voltage clamping in low current density, and the self-humidification without any external humidifiers. The former restrains catalyst decay in small load working conditions, and the latter is beneficial for improving the cold-start ability. In this study, dynamic performances and stable characteristics of a fuel cell system with dual exhaust gas recirculation are firstly experimentally studied using an orthogonal test method. System parameters, including humidification temperature of cathode external humidifier, fresh air stoichiometric ratio (SR), current density, cathode and anode recirculation pump speeds, are regarded as key factors in the experiments based on the testing conditions of the test-bench. Two four-factor and three-level orthogonal tables are designed, and the effects of key factors on system performance indices (average cell voltage, relative humidity (RH) at cathode inlet, high frequency resistance (HFR), oxygen concentrations at cathode inlet and outlet, and the concentration difference between these two positions) are investigated. Results show that: (1) with the cathode recirculation, the cell voltage can be reduced in low current densities by coordinately adjusting the recycled gas flow and reducing fresh air SR; (2) with the dual recirculation, the fuel cell membrane can be well hydrated, and system performance only shows 3% reduction compared with a system with an external humidifier; (3) the difference between the oxygen molar concentration at the inlet and outlet of cathode gas channels becomes small using dual recirculation. [ABSTRACT FROM AUTHOR]

Durability and start-up ability in sub-zero environment are two technical bottlenecks of vehicular polymer electrolyte membrane (PEM) fuel cell systems. With exhaust gas recirculation on the anode and cathode side, the cell voltage at low current density can be reduced, and the membrane can be humidified without external humidifier. They may be helpful to prolong the working lifetime and to promote the start-up ability. This paper presents an experimental study on a PEM fuel cell system with anodic and cathodic recirculation. The system is built up based on a 10 kW fuel cell stack, which consists of 50 cells and has an active area of 261 cm 2 . A cathodic recirculation pump and a hydrogen recirculation pump are utilized on the cathode and anode side, respectively. Key parameters, e.g., stack current, stack voltage, cell voltage, air flow, relative humidity on the cathode side, oxygen concentration at the inlet and outlet of the cathode side, are measured. Results show that: 1) with a cathodic recirculation the system gets good self-humidification effect, which is similar to that with an external humidifier; 2) with a cathodic recirculation and a reduction of fresh air flux, the cell voltage can be obviously reduced; 3) with an anodic recirculation the cell voltage can also be reduced due to a reduction in the hydrogen partial pressure, the relative humidity on the cathode side is a little smaller than the case with only cathode recirculation. It indicates that, for our stack the cathodic recirculation is effective to clamp cell voltage at low current density, and a self-humidification system is possible with cathodic recirculation. Further study will focus on the dynamic model and control of the dual recirculation fuel cell system. [ABSTRACT FROM AUTHOR]

The historical and technological development of the ubiquitous trench power MOSFET (or vertical trench VDMOS) is described. Overcoming the deficiencies of VMOS and planar VDMOS, trench VDMOS innovations include pioneering efforts in reactive ion etching and oxidation of the silicon trench gate, polysilicon fill and recessed etchback, unit cell and distributed voltage clamping to protect the trench gate, and scaling active cells to high densities using deep submicron fabrication. Thereafter, gate–drain engineered trench VDMOS improved high-frequency switching capability with lower gate charge utilizing nonuniform gate oxides, field shaping, and charge balancing (superjunction, RSO) methods. The recent adaptation of trench gates in wide bandgap unipolar devices is also described. [ABSTRACT FROM AUTHOR]

Certain voltage-activated Ca 2 + channels have been reported to act as potential zinc entry routes. However, it remains to be determined whether zinc can permeate individual Ca 2 + channel isoforms. We expressed recombinant Ca 2 + channel isoforms in Xenopus oocytes and attempted to record zinc currents from them using a two-electrode voltage clamp method. We found that, in an extracellular zinc solution, inward currents arising from zinc permeation could be recorded from Xenopus oocytes expressing L-type Ca v 1.2 or Ca v 1.3 isoforms, but not from oocytes expressing Ca v 2.2, Ca v 2.3, Ca v 3.1, or Ca v 3.2. Zinc currents through Ca v 1.2 and Ca v 1.3 were blocked by nimodipine, but enhanced by (±)Bay K8644, supporting the finding that zinc can permeate both L-type Ca v 1.2 and Ca v 1.3 channel isoforms. We also examined the blocking effects of low concentrations of zinc on Ca 2 + currents through the L-type channel isoforms. Low micro-molar zinc potently blocked Ca 2 + currents through Ca v 1.2 and Ca v 1.3 with different sensitivities (IC 50 for Ca v 1.2 and Ca v 1.3 = 18.4 and 34.1 μM) and de-accelerated the activation and inactivation kinetics in a concentration-dependent manner. Notably, mild acidifications of the external zinc solution increased zinc currents through Ca v 1.2 and Ca v 1.3, with the increment level for Ca v 1.3 being greater than that for Ca v 1.2. In overall, we provide evidence that Ca v 1.2 and Ca v 1.3 isoforms are capable of potentially functioning as zinc permeation routes, through which zinc entry can be differentially augmented by mild acidifications. [ABSTRACT FROM AUTHOR]

Glucose-dependent insulinotropic polypeptide (GIP) secreted from jejunal mucosal K cells augments insulin secretion and plays a critical role in the pathogenesis of obesity and Type 2 diabetes mellitus. In recent studies, we have shown GIP directly activates Na-glucose cotransporter-1 (SGLT1) and enhances glucose absorption in mouse jejunum. It is not known whether GIP would also regulate other intestinal nutrient absorptive processes. The present study investigated the effect of GIP on proton-peptide cotransporter- 1 (PepT1) that mediates di- and tripeptide absorption as well as peptidomimetic drugs. Immunohistochemistry studies localized both GIP receptor (GIPR) and PepT1 proteins on the basolateral and apical membranes of normal mouse jejunum, respectively. Anti-GIPR antibody detected 50-, 55-, 65-, and 70-kDa proteins, whereas anti-PepT1 detected a 70-kDa proteins in mucosal homogenates of mouse jejunum. RT-PCR analyses established the expression of GIPR- and PepT1-specific mRNA in mucosal cells of mouse jejunum. Absorption of Gly-Sar (a nondigestible dipeptide) measured under voltageclamp conditions revealed that the imposed mucosal H+ gradientenhanced Gly-Sar absorption as an evidence for the presence of PepT1-mediated H+:Gly-Sar cotransport on the apical membranes of mouse jejunum. H+:Gly-Sar absorption was completely inhibited by cephalexin (a competitive inhibitor of PepT1) and was activated by GIP. The GIP-activated Gly-Sar absorption was completely inhibited by RP-cAMP (a cAMP antagonist). In contrast to GIP, the ileal L cell secreting glucagon-like peptide-1 (GLP-1) did not affect the H+:Gly- Sar absorption in mouse jejunum. We conclude from these observations that GIP, but not GLP-1, directly activates PepT1 activity by a cAMP-dependent signaling pathway in jejunum. [ABSTRACT FROM AUTHOR]

Abstract: Voltage-activated Ca2+ channels are membrane protein machinery performing selective permeation of external calcium ions. The main Ca2+ selective filters of all high-voltage-activated Ca2+ channel isoforms are commonly composed of four Glu residues (EEEE), while those of low-voltage-activated T-type Ca2+ channel isoforms are made up of two Glu and two Asp residues (EEDD). We here investigate how the Asp residues at the pore loops of domains III and IV affect biophysical properties of the Cav3.2 channel. Electrophysiological characterization of the pore mutant channels in which the pore Asp residue(s) were replaced with Glu, showed that both Asp residues critically control the biophysical properties of Cav3.2, including relative permeability between Ba2+ and Ca2+, anomalous mole fraction effect (AMFE), voltage dependency of channel activation, Cd2+ blocking sensitivity, and pH effects, in distinctive ways. [Copyright &y& Elsevier]

The aim of this study is to develop a high-efficiency single-input multiple-output (SIMO) dc–dc converter. The proposed converter can boost the voltage of a low-voltage input power source to a controllable high-voltage dc bus and middle-voltage output terminals. The high-voltage dc bus can take as the main power for a high-voltage dc load or the front terminal of a dc–ac inverter. Moreover, middle-voltage output terminals can supply powers for individual middle-voltage dc loads or for charging auxiliary power sources (e.g., battery modules). In this study, a coupled-inductor-based dc–dc converter scheme utilizes only one power switch with the properties of voltage clamping and soft switching, and the corresponding device specifications are adequately designed. As a result, the objectives of high-efficiency power conversion, high step-up ratio, and various output voltages with different levels can be obtained. Some experimental results via a kilowatt-level prototype are given to verify the effectiveness of the proposed SIMO dc–dc converter in practical applications. [ABSTRACT FROM AUTHOR]

Although both Kcnn4c and Kcnma1 channels are present on colonic mucosal membranes, only Kcnma1 has been suggested to mediate K+ secretion in the colon. Therefore, studies were initiated to investigate the relative roles of Kcnn4c and Kcnma1 in mediating aldosterone (Na-free diet)-induced K+ secretion. Mucosal to serosal (m-s), serosal to mucosal (s-m), and net 86Rb+ (K+ surrogate) fluxes as well as short circuit currents (Isc; measure of net ion movement) were measured under voltage clamp condition in rat distal colon. Active K+ absorption, but not K+ secretion, is present in normal, while aldosterone induces active K+ secretion (1.04 ± 0.26 vs. -1.21 ± 0.15 μeq·h-1·cm-2; P < 0.001) in rat distal colon. Mucosal VO4 (a P-type ATPase inhibitor) inhibited the net K+ absorption in normal, while it significantly enhanced net K+ secretion in aldosterone animals. The aldosterone-induced K+ secretion was inhibited by the mucosal addition of 1) either Ba2+ (a nonspecific K+ channel blocker) or charybdotoxin (CTX; a common Kcnn4 and Kcnma1 channel blocker) by 89%; 2) tetraethyl ammonium (TEA) or iberiotoxin (IbTX; a Kcnma1 channel blocker) by 64%; and 3) TRAM-34 (a Kcnn4 channel blocker) by 29%. TRAM- 34, but not TEA, in the presence of IbTX further significantly inhibited the aldosterone-induced K+ secretion. Thus the aldosterone-induced Ba2+/CTX-sensitive K+ secretion consists of IbTX/TEAsensitive (Kcnma1) and IbTX/TEA-insensitive fractions. TRAM-34 inhibition of the IbTX-insensitive fraction is consistent with the aldosterone-induced K+ secretion being mediated partially via Kcnn4c. Western and quantitative PCR analyses indicated that aldosterone enhanced both Kcnn4c and Kcnma1α protein expression and mRNA abundance. In vitro exposure of isolated normal colonic mucosa to aldosterone also enhanced Kcnn4c and Kcnma1α mRNA levels, and this was prevented by exposure to actinomycin D (an RNA synthesis inhibitor). These observations indicate that aldosterone induces active K+ secretion by enhancing mucosal Kcnn4c and Kcnma1 expression at the transcriptional level. [ABSTRACT FROM AUTHOR]

Redox regulation is one of the ubiquitous mechanisms to modulate ion channels. We here investigated how 5,5'-dithio-bis (2-nitrobenzoic acid), a cysteine specific oxidizing reagent, modulates Cav3.1 and Cav3.2 T-type Ca2 + channels expressed in Xenopus oocytes. Application of the reagent inhibited Cav3.1 and Cav3.2 currents in a dose-dependent manner. The oxidizing reagent (1 mM) reduced the peak amplitude of Cav3.1 and Cav3.2 currents by ~50% over 2-3 minutes and the decreased currents were fully recovered upon washout of it. The reagent slowed the activation and inactivation kinetics of Cav3.1, Cav3.2, and Cav3.3 channel currents. Notably, the reagent positively shifted both activation and steady-state inactivation curves of Cav3.1, while it did not those of Cav3.2. Utilizing chimeric channels from Cav3.1 and Cav3.2, we localized the domains III and IV of Cav3.1 responsible for the positive shifts of channel activation and steady-state inactivation. These findings provide hints relevant to the electrophysiological and molecular mechanisms accounting for the oxidative regulation of T-type channels. [ABSTRACT FROM AUTHOR]

Abstract: We have cloned a hamster Cav1.3 variant with a long carboxyl terminus. This differs from the first hamster Cav1.3 clone which has a short carboxyl terminus. When relative expression levels of the two variants were examined using quantitative RT-PCR, the long Cav1.3 transcripts were detected abundantly in the brain and testis, moderately in the heart, pancreas, and kidney, and weakly in the lung. Comparatively, the short Cav1.3 transcripts were detected less abundantly in most of the tissues. The two Cav1.3 variants were reconstituted in Xenopus oocytes and their electrophysiological properties were characterized using a two-electrode voltage clamping method. The long Cav1.3 variant was ~5-fold better expressed than the short Cav1.3 variant. When Ca2+ was used as a charge carrier, the long Cav1.3 variant containing an IQ (Ile-Gln) motif displayed strong calcium-dependent inactivation, while the short variant that was deficient of an IQ motif showed little calcium-dependent inactivation. Examination of other biophysical properties revealed that potentials for activation threshold, peak current, and half-activation and inactivation of the long Cav1.3 were significantly lower than those of the short Cav1.3. These findings suggest that the long carboxyl tail plays crucial roles in not only facilitating calcium-dependent inactivation, but also improving expression and negative shifting of the activation and inactivation properties. [Copyright &y& Elsevier]

Abstract: We show here the expression, permeability and pharmacology of a voltage-gated channel in certain taste bud cells (TBCs) which is known to be permeable to Lucifer Yellow CH (LY) and known to release ATP as a neurotransmitter in response to taste substances. LY dissolved in a 200mM K+-containing solution label TBCs immunoreactive to PLCβ2, a phospholipase subtype, but not the TBC subtype immunoreactive to SNAP-25, a SNARE protein. In addition to these subtypes, LY also labelled a few of the non-immunoreactive TBCs. Monovalent and divalent anion probes with molar mass less than 1200 also label PLCβ2-immunoreactive TBCs and a few non-immunoreactive TBCs, whereas a cation probe, rhodamine B, labels the cell membrane of TBCs nonselectively and K+ independently. The number of LY-labelled TBCs is decreased by 5μM DIDS (4,4′-diisothiocyanostilbene-2-2′disulfonate), 1mM octanol and 10−5 M H+, but not by 10μM carbenoxolone, 2mM probenecid, 10mM TEA, or 30μM flufenamic acid. PLCβ2-immunoreactive TBCs and a few non-immunoreactive TBCs generate a TEA-insensitive outwardly rectifying current. DIDS decreases this current in magnitude with IC50 of ~0.4μM in a voltage-independent manner. Also 10−5 M H+ and 1mM octanol decreases the current magnitude, but 10μM carbenoxolone and 2mM probenecid do not. These results show that the LY-permeable channel preferably permeates anions and occurs not only on PLCβ2-immunoreactive TBCs but also on certain non-immunoreactive TBCs. Also the results show that the pharmacology of the LY-permeable channel is different from hemichannels reported. The discussion focuses on the pharmacology and the role of the LY-permeable channel. [ABSTRACT FROM AUTHOR]

Abstract: Electrophysiological characterization of T-type Ca2+ channel isoforms (Cav3.1, Cav3.2, and Cav3.3) has shown that all of the isoforms are low voltage-activated around resting membrane potential, but their current kinetics are distinctly different, with the activation and inactivation kinetics of the Cav3.1 and Cav3.2 channels being much faster than those of the Cav3.3 channel. We previously reported that multiple structural regions of the Cav3.3 T-type channel participate in determining its current kinetics. Here we have evaluated the relative contributions of individual cytoplasmic and trans-membrane regions to the current kinetics of the channel, by systematically replacing individual regions of Cav3.3 with the corresponding regions of Cav3.1. Introduction of the Cav3.1 III–IV loop into the Cav3.3 backbone accelerated both the activation and inactivation kinetics more prominently than any other intracellular loop or tail. Among the trans-membrane domains, introduction of the domain I of Cav3.1 into Cav3.3 accelerated both the activation and inactivation kinetics most effectively. These findings suggest that the current kinetics of the Cav3.3 channel are differentially controlled by several structural regions, among which the III–IV loop and domain I are the most prominent in governing both activation and inactivation kinetics. [Copyright &y& Elsevier]

This paper mainly focuses on the development of a high-efficiency power conversion system for kilowatt-level stand-alone generation units with a low output voltage, such as photovoltaic modules, fuel cells, and small-scale wind generators, and it aims at having the same output ac voltage, i.e., 110 Vrms/ 60 Hz as the utility power for the utilization of a stand-alone power supply. This high-efficiency power conversion system includes one high-efficiency high-step-up dc-dc converter and one soft-switching dc-ac current-source inverter. This dc-dc converter is capable of solving the voltage spike problem while the switch is turned off, and it can achieve the objectives of high efficiency and high voltage gain. Because the techniques of soft switching and voltage clamping are used in the dc-ac current-source inverter, the conversion efficiency could greatly be improved. The effectiveness of the designed circuits is verified by experimentation, and the maximum efficiency of the entire high-efficiency power conversion system is Over 91% based on the experimental measurements. [ABSTRACT FROM AUTHOR]

Abstract: We recently reported that a histidine (H191) in the S3–S4 loop of domain I is critical for nickel inhibition of the Cav3.2 T-type Ca2+ channel. As in Cav3.2, two histidine residues are commonly found in the IS3–IS4 loops of mammalian Cav2.3 Ca2+ channels, which are also blocked by low micromolar concentrations of nickel. We show here by site-directed mutagenesis and electrophysiology that both residues contribute to the nickel sensitivity of Cav2.3, with H183 being more critical than H179. These findings strongly suggest that both H179 and H183 in the IS3–IS4 loop are essential structural determinants required for nickel sensitive inhibition of the Cav2.3. [Copyright &y& Elsevier]

This study focuses on the development of a high-efficiency bidirectional converter for power sources with large voltage diversity. In conventional bidirectional converters, transformer-based circuit topologies are commonly employed and soft-switching techniques including zero-voltage-switching (ZVS) or zero-current-switching (ZCS) are frequently applied to mitigate corresponding switching losses. Unfortunately, switches of four and upward in these transformer-based schemes increase production costs and reduce conversion efficiency. In this study, a coupled-inductor bidirectional converter scheme utilizes only three power switches to fulfill the objective of bidirectional current control. The high step-up and step-down ratios enable a battery module with a low voltage to be injected into a high-voltage dc bus for subsequent utilization. Some experimental results are given to verify the effectiveness of the proposed bidirectional converter. Since the techniques of voltage clamping, synchronous rectification and soft switching are exploited in this circuit topology, and the corresponding device specifications are adequately fulfilled, it can provide high-efficiency bidirectional power conversion for power sources with large voltage diversity. [ABSTRACT FROM AUTHOR]

A novel diode-triggered silicon-controlled rectifier (DTSCR) (Mergens et al., 2003) electrostatic discharge (ESD) protection element is introduced for low-voltage application (signal and supply voltages ≤ 1.8 V) with extremely narrow ESD design margins. Trigger-voltage engineering in conjunction with fast and efficient SCR voltage clamping is applied for the protection of ultrasensitive circuit nodes, such as SiGe heterojunction bipolar transistor (HBT) base regions (e.g., fTmax=45 GHz in BiCMOS 0.35-μm LNA input) and thin gate oxides (e.g., tox=1.7 nm in CMOS 0.09-μm high-speed input). Ultrathin gate protection requires a reinforced trigger diode chain to avoid SCR trigger-speed issues resulting in critical trigger-voltage overshoots for very fast ESD transients such as a charged device model (CDM). SCR integration can be realized based on parasitic n-p-n/p-n-p inherent to CMOS devices or can alternatively be implemented based on vertical high-speed SiGe HBT with adjacent p+ SCR anode. [ABSTRACT FROM PUBLISHER]

Transepithelial K + absorption requires apical K + uptake and basolateral K + exit. In the colon, apical H + -K + -ATPase mediates cellular K + uptake, and it has been suggested that electroneutral basolateral K + exit reflects K + -Cl - cotransporter-1 (KCC1) operating in parallel with K + and Cl - channels. The present study was designed to identify basolateral transporter(s) responsible for K + exit in rat distal colon. Active K + absorption was determined by measuring 86 Rb + (K + surrogate) fluxes across colonic epithelia under voltage-clamp conditions. With zero Cl - in the mucosal solution, net K + absorption was reduced by 38%, indicating that K + absorption was partially Cl - -dependent. Serosal addition of DIOA (KCC1 inhibitor) or Ba 2+ (nonspecific K + channel blocker) inhibited net K + absorption by 21% or 61%, respectively, suggesting that both KCC1 and K + channels contribute to basolateral K + exit. Clotrimazole and TRAM34 (IK channel blockers) added serosally inhibited net K + absorption, pointing to the involvement of IK channels in basolateral K + exit. GaTx2 (CLC2 blocker) added serosally also inhibited net K + absorption, suggesting that CLC2-mediated Cl - exit accompanies IK channel-mediated K + exit across the basolateral membrane. Net K + absorption was not inhibited by serosal addition of either IbTX (BK channel blocker), apamin (SK channel blocker), chromanol 293B (K V 7 channel blocker), or CFTR inh172 (CFTR blocker). Immunofluorescence studies confirmed basolateral membrane colocalization of CLC2-like proteins and Na + -K + -ATPase α-subunits. We conclude that active K + absorption in rat distal colon involves electroneutral basolateral K + exit, which may reflect IK and CLC2 channels operating in parallel. NEW & NOTEWORTHY This study demonstrates that during active electroneutral K + absorption in rat distal colon, K + exit across the basolateral membrane mainly reflects intermediate conductance K + channels operating in conjunction with chloride channel 2, with a smaller, but significant, contribution from K + -Cl - cotransporter-1 (KCC1) activity.

A dual-input high step-up isolated converter (DHSIC) is proposed in this paper, which incorporates Sheppard Taylor circuit into power stage design so as to step up voltage gain. In addition, the main circuit adopts boosting capacitors and switched capacitors, based on which the converter voltage gain can further be improved significantly. Since the proposed converter possesses an inherently ultra-high step-up feature, it is capable of processing low input voltages. The DHSIC also has the important features of leakage energy recycling, switch voltage clamping, and continuous input-current obtaining. These characteristics advantage converter efficiency and benefit the DHSIC for high power applications. The structure of the proposed converter is concise. That is, it can lower cost and simplifies control approach. The operation principle and theoretical derivation of the proposed converter are discussed thoroughly in this paper. Simulations and hardware implementation are carried out to verify the correctness of theoretical analysis and to validate feasibility of the converter as well. [ABSTRACT FROM AUTHOR]

In this paper, a novel AC magnetic transmitter current source circuit is proposed for application of frequency domain electromagnetic method (FEM) prospecting. The proposed current source circuit is capable of generating high frequency and high constant amplitude currents, which are key technical problems for FEM. It is suitable for very wide frequencies. The main circuit of the proposed current source consists of a rising-edge enhancing unit, a constant current control unit, and a high voltage clamping unit. Large constant clamping voltage is applied during the rising edge and the falling edge of the alternating square current to obtain a high frequency and high linearity current source. On the current flat stage, the constant current unit provides the energy to the load to ensure the constant amplitude of the output current. Detailed operations of the proposed magnetic current source are given. Simulation and experimental results demonstrate that the proposed circuit achieves short reversal time, the linearity of the rising/falling edge, constant amplitude and low power loss. These are the desired characteristics of the ac square current source probing transmitter for the magnetic FEM applications. [ABSTRACT FROM AUTHOR]

Voltage-gated ion channels (VGICs) of excitable tissues are emerging as targets likely involved in both the therapeutic and toxic effects of inhaled and intravenous general anesthetics. Whereas sevoflurane and propofol inhibit voltage-gated Na + channels (Navs), sevoflurane potentiates certain voltage-gated K + channels (Kvs). The combination of these effects would dampen neural excitability and, therefore, might contribute to the clinical endpoints of general anesthesia. As the body of work regarding the interaction of general anesthetics with VGICs continues to grow, a multidisciplinary approach involving functional, biochemical, structural, and computational techniques, many of which are detailed in other chapters, has increasingly become necessary to solve the molecular mechanism of general anesthetic action on VGICs. Here, we focus on electrophysiological and modeling approaches and methodologies to describe how our work has elucidated the biophysical basis of the inhibition Navs by propofol and the potentiation of Kvs by sevoflurane., (© 2018 Elsevier Inc. All rights reserved.)

The Cav1.2 Ca2+ channel is essential for cardiac and smooth muscle contractility and many physiological functions. We mutated single, double, and quadruple sites of the four potential Asn (N)-glycosylation sites in the rabbit Cav1.2 into Gln (Q) to explore the effects of Nglycosylation. When a single mutant (N124Q, N299Q, N1359Q, or N1410Q) or Cav1.2/WT was expressed in Xenopus oocytes, the biophysical properties of single mutants were not significantly different from Cav1.2/WT. In comparison, the double mutant N124,299Q showed a positive shift in voltage-dependent gating. Furthermore, the quadruple mutant (QM; N124,299,1359,1410Q) showed a positive shift in voltage-dependent gating as well as a reduction of current. We tagged EGFP to the QM, double mutants, and Cav1.2/WT to chase the mechanisms underlying the reduced currents of QM. The surface fluorescence intensity of QM was weaker than that of Cav1.2/WT, suggesting that the reduced current of QM arises from its lower surface expression than Cav1.2/WT. Tunicamycin treatment of oocytes expressing Cav1.2/WT mimicked the effects of the quadruple mutations. These findings suggest that Nglycosylation contributes to the surface expression and voltage-dependent gating of Cav1.2.