The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier...The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier K+ outward currents were measured in isolated guinea pig single myocytes using the whole-cell configuration of the patch-clamp technique. Currents were measured in response to 300 ms depolarizing pulses from a holding potential of -40 mV in three experimental protocols [control, isoproterenol (10^(9)mol/L - 10^(-6) mol/L ), and isoproterenol (10^(-9)mol/L - 10^(-6)mol/L ) plus either d, l-Sotalol (10^(-4) mol/L) or d-Sotalol (10^(-4) mol/L)]. IK tail currents were measured upon repolarization to -40 mV. It was found that Ik was significantly amplified in the presence. of isoproterenol (10^(-9) mol/L- 10^(-6) mol/L) plus d-Sotalol. At 10-8 mol/L isoproterenol, Ik was increased by 92. 7%±17. 1 % (P<0. 05) and 54. 3 %±13. 4 % after d-Sotalol addition (P<0. 05). In contrast, d, l-Sotalol completely conteracted the increase of iK by isoproterenol (<10^(-8) mol/L), and compared to control, Ic was decreased by 35. 6 % ±8. 1% at 10^(-8) mol/L isoproterenol plus d, l-Sotalol (P<0. 05). It is concluded that the β-adrenergic blocking property of d, l-Sotalol but not that of dSotalol maintains the delayed rectifier K+ outward current blockade in the presence of isoproterenol in guinea pig myocytes. This might contribute to a superior antiarrhythmic efficacy as compared to d-Sotalol.展开更多
Objective:To study the effects of sodium ferulate on the ultrarapid delayed rectifier K^+ current(IKur) in human atrial myocytes. Methods:Human atrial myocytes were isolated by enzyme dispersion method. IKur, in ...Objective:To study the effects of sodium ferulate on the ultrarapid delayed rectifier K^+ current(IKur) in human atrial myocytes. Methods:Human atrial myocytes were isolated by enzyme dispersion method. IKur, in human atrial myocytes were recorded by using the whole cell patch clamp. The changes of IKur were compared in the absence and the presence of sodium ferulate. Results:There was no effect of 0.4 g/L sodium ferulate on I-V relation of IKur. However, 0.4 g/L sodium ferulate inhibited IKur to some degrees at each test pulse. The current densities of IKur at +60 mV decreased from 4.997 ± 0.35 PA/PF to 3.331 ± 0.26 PA/PF(n = 6, P 〈 0.05). The inhibitory effect was concentration-dependent. IC50 was(0.41 ±0.03)g/L and the Hill coefficient was 0.95 ± 0.05. Conclusion:Sodium ferulate as a potassium channel blocker can inhibit IKur in human atrial myocytes effectively.展开更多
Aim Evidence has shown that stimulation of alA-adrenorecetors receptor (alA-AR) or angiotensin II type 1 receptor (AT1R) acutely down-regulates the rapid component of the delayed rectifier K + current (IKr) via...Aim Evidence has shown that stimulation of alA-adrenorecetors receptor (alA-AR) or angiotensin II type 1 receptor (AT1R) acutely down-regulates the rapid component of the delayed rectifier K + current (IKr) via protein kinase C (PKC). This study was designed to investigate which PKC isozymes mediate down-regulations of IKr by alA-AR and AT1R. Method The whole-cell patch-clamp technique was used to record IKr in native cardio- myocytes and in human embryonic kidney (HEK) 293 cells co-transfected with human ether-a-go-go related gene (hERG) encoding α-subunit of IKr and human alA-AR or AT1R gene. Result In isolated guinea-pig ventricular cardiomyocytes the inhibitory action of Ang II on IKr was little affected by Go6976 (selectively inhibiting PKCα, β and γ) and Go6983 (selectively inhibiting PKCα, β, γ , δ, and ζ), but was significantly antagonized by an inter- nal dialysis with PKCe-selective inhibitory peptide εV1 -2. In contrast, the inhibitory action of alA-AR agonist A61603 on IKr was remarkably attenuated by Go6976 or Go6983, but not affected by peptide εV1 -2. Moreover, specific PKC-selective inhibitory peptide antagonized the effect of A61603. The results suggested that PKCe and PKCα isoform respectively mediated the inhibitory effect of AT1R and a1A-AR. In heterologous expression system, both PKCα and e-selective activator peptides down regulated hERG current with different manner. PKCα activator peptide shifted the activation curve of the channel to the right, but PKCe-selective activator peptide did not. Simi- larly, A61603 shifted the activation curve to the right, whereas Ang Ⅱ had no effect. In addition, both A61603 and PKCα activator peptide showed inhibitory action on bERG A PKC current (an bERG mutant in which 17 of the 18 ROSITE-predicted PKC acceptor serines/threonines were changed to alanine) with a similar potency to wild type bERG current. But, both Ang Ⅱ and PKCe-selective activator peptide exhibited no effects on bERG △ PKC cur- rent. The results indicated that PKCα and PKCe isoforms down-regulated bERG current through different mecha- nism. Conclusion PKCα and PKCe isoform respectively mediates the inhibition on IKr by stimulation of AT1R and alA-AR via different molecular mechanism.展开更多
The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the elec...The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.展开更多
This paper presents a new current conveyor (CCII+) full-wave rectifier for low frequency/small signal medical applications. The proposed rectifier is based on the current conveyor full-wave rectifier proposed previous...This paper presents a new current conveyor (CCII+) full-wave rectifier for low frequency/small signal medical applications. The proposed rectifier is based on the current conveyor full-wave rectifier proposed previously, but the proposed rectifier is better in view of no need diodes to rectify, and no need bias sources to overcome the zero crossing error. It needs only two CCII+s, two resistors, and three simple current mirrors, which is easy for IC implementation and for building in many countries. The PSPICE simulation with the current conveyor CCII+ in the current feedback opamp AD844 IC and the 2N2222 bipolar current mirror shows the good low frequency/small signal rectification, the operation voltage of down to 6 .展开更多
On the basis of detailed analysis of a novel harmonic counteracting method which can be used to effectively compensate the supply line harmonic currents of a passive single phase diode bridge rectifier, this paper pr...On the basis of detailed analysis of a novel harmonic counteracting method which can be used to effectively compensate the supply line harmonic currents of a passive single phase diode bridge rectifier, this paper presents two simpler single phase diode bridge rectifier configurations and their alternatives which can achieve low supply line current THD(total harmonic distortion) too. Moreover, this paper also proposes a few passive hamonic counteracting networks for multi single phase rectifiers which are connected in parallel.展开更多
To solve the input current harmonic pollution of the high power rectifier system,18-pulse rectifier based on a kind of active harmonic suppression technique at dc side is proposed in this paper.The pulse rectifier emp...To solve the input current harmonic pollution of the high power rectifier system,18-pulse rectifier based on a kind of active harmonic suppression technique at dc side is proposed in this paper.The pulse rectifier employs three-phase diode bridges,each of them followed by a boost converter.Unlike the conventional three-phase unity-power-factor diode rectifier,the ideal sinusoidal main currents of circuit topology are obtained by control its output current or input currents of three boost converters for approximately triangular modulation.The theoretical of modulation strategy and characteristics of input and output currents about the proposed rectifier are analyzed in detail.Simulation results by Matlab/Simulink demonstrate that the proposed rectifier draws nearly sinusoidal current and power quality index is improved.The correctness of the theoretical analysis is validated.展开更多
A junction barrier Schottky (JBS) rectifier with an improved P-well on 4H-SiC is proposed to improve the VF-IR trade-off and the breakdown voltage. The reverse current density of the proposed JBS rectifier at 300 K ...A junction barrier Schottky (JBS) rectifier with an improved P-well on 4H-SiC is proposed to improve the VF-IR trade-off and the breakdown voltage. The reverse current density of the proposed JBS rectifier at 300 K and 800 V is about 3.3 × 10-s times that of the common JBS rectifier at no expense of the forward voltage drop. This is because the depletion layer thickness in the P-well region at the same reverse voltage is larger than in the P+ grid, resulting in a lower spreading current and tunneling current. As a result, the breakdown voltage of the proposed JBS rectifier is over 1.6 kV, that is about 0.8 times more than that of the common JBS rectifier due to the uniform electric field. Although the series resistance of the proposed JBS rectifier is a little larger than that of the common JBS rectifier, the figure of merit (FOM) of the proposed JBS rectifier is about 2.9 times that of the common JBS rectifier. Based on simulating the values of susceptibility of the two JBS rectifiers to electrostatic discharge (ESD) in the human body model (HBM) circuits, the failure energy of the proposed JBS rectifier increases 17% compared with that of the common JBS rectifier.展开更多
A robust electron device called the enhanced gated-diode-triggered silicon-controlled rectifier (EGDTSCR) for electrostatic discharge (ESD) protection applications has been proposed and implemented in a 0.18-μm 5-V/2...A robust electron device called the enhanced gated-diode-triggered silicon-controlled rectifier (EGDTSCR) for electrostatic discharge (ESD) protection applications has been proposed and implemented in a 0.18-μm 5-V/24-V BCD process. The proposed EGDTSCR is constructed by adding two gated diodes into a conventional ESD device called the modified lateral silicon-controlled rectifier (MLSCR). With the shunting effect of the surface gated diode path, the proposed EGDTSCR, with a width of 50 μm, exhibits a higher failure current (i.e., 3.82 A) as well as a higher holding voltage (i.e., 10.21 V) than the MLSCR.展开更多
电流源型脉宽调制(Pulse width modulation,PWM)整流器因其网侧存在LC滤波器,系统的控制难度增加。传统直接功率控制策略下的整流器功率波形存在脉动,因模型预测控制具有卓越的动态特性以及直观的控制规律,采用模型预测直接功率控制(Mod...电流源型脉宽调制(Pulse width modulation,PWM)整流器因其网侧存在LC滤波器,系统的控制难度增加。传统直接功率控制策略下的整流器功率波形存在脉动,因模型预测控制具有卓越的动态特性以及直观的控制规律,采用模型预测直接功率控制(Model predictive direct power control,MPDPC)对传统控制策略进行改进。首先建立了三相PWM整流器的数学模型,给出了每个采样周期内的功率变化率,并推导出相邻采样周期之间的功率关系,然后给出基于单矢量的模型预测直接功率控制策略,提出了基于双矢量的模型预测直接功率控制策略,并优选出两个电流矢量,计算在一个采样周期内的作用时间,并对其进行修正。最后,在Matlab/Simulink仿真软件验证了所提控制策略的可行性和有效性。展开更多
文摘The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier K+ outward currents were measured in isolated guinea pig single myocytes using the whole-cell configuration of the patch-clamp technique. Currents were measured in response to 300 ms depolarizing pulses from a holding potential of -40 mV in three experimental protocols [control, isoproterenol (10^(9)mol/L - 10^(-6) mol/L ), and isoproterenol (10^(-9)mol/L - 10^(-6)mol/L ) plus either d, l-Sotalol (10^(-4) mol/L) or d-Sotalol (10^(-4) mol/L)]. IK tail currents were measured upon repolarization to -40 mV. It was found that Ik was significantly amplified in the presence. of isoproterenol (10^(-9) mol/L- 10^(-6) mol/L) plus d-Sotalol. At 10-8 mol/L isoproterenol, Ik was increased by 92. 7%±17. 1 % (P<0. 05) and 54. 3 %±13. 4 % after d-Sotalol addition (P<0. 05). In contrast, d, l-Sotalol completely conteracted the increase of iK by isoproterenol (<10^(-8) mol/L), and compared to control, Ic was decreased by 35. 6 % ±8. 1% at 10^(-8) mol/L isoproterenol plus d, l-Sotalol (P<0. 05). It is concluded that the β-adrenergic blocking property of d, l-Sotalol but not that of dSotalol maintains the delayed rectifier K+ outward current blockade in the presence of isoproterenol in guinea pig myocytes. This might contribute to a superior antiarrhythmic efficacy as compared to d-Sotalol.
基金This work was supported by the National Natural Science Foundation of China(No.30700747)
文摘Objective:To study the effects of sodium ferulate on the ultrarapid delayed rectifier K^+ current(IKur) in human atrial myocytes. Methods:Human atrial myocytes were isolated by enzyme dispersion method. IKur, in human atrial myocytes were recorded by using the whole cell patch clamp. The changes of IKur were compared in the absence and the presence of sodium ferulate. Results:There was no effect of 0.4 g/L sodium ferulate on I-V relation of IKur. However, 0.4 g/L sodium ferulate inhibited IKur to some degrees at each test pulse. The current densities of IKur at +60 mV decreased from 4.997 ± 0.35 PA/PF to 3.331 ± 0.26 PA/PF(n = 6, P 〈 0.05). The inhibitory effect was concentration-dependent. IC50 was(0.41 ±0.03)g/L and the Hill coefficient was 0.95 ± 0.05. Conclusion:Sodium ferulate as a potassium channel blocker can inhibit IKur in human atrial myocytes effectively.
文摘Aim Evidence has shown that stimulation of alA-adrenorecetors receptor (alA-AR) or angiotensin II type 1 receptor (AT1R) acutely down-regulates the rapid component of the delayed rectifier K + current (IKr) via protein kinase C (PKC). This study was designed to investigate which PKC isozymes mediate down-regulations of IKr by alA-AR and AT1R. Method The whole-cell patch-clamp technique was used to record IKr in native cardio- myocytes and in human embryonic kidney (HEK) 293 cells co-transfected with human ether-a-go-go related gene (hERG) encoding α-subunit of IKr and human alA-AR or AT1R gene. Result In isolated guinea-pig ventricular cardiomyocytes the inhibitory action of Ang II on IKr was little affected by Go6976 (selectively inhibiting PKCα, β and γ) and Go6983 (selectively inhibiting PKCα, β, γ , δ, and ζ), but was significantly antagonized by an inter- nal dialysis with PKCe-selective inhibitory peptide εV1 -2. In contrast, the inhibitory action of alA-AR agonist A61603 on IKr was remarkably attenuated by Go6976 or Go6983, but not affected by peptide εV1 -2. Moreover, specific PKC-selective inhibitory peptide antagonized the effect of A61603. The results suggested that PKCe and PKCα isoform respectively mediated the inhibitory effect of AT1R and a1A-AR. In heterologous expression system, both PKCα and e-selective activator peptides down regulated hERG current with different manner. PKCα activator peptide shifted the activation curve of the channel to the right, but PKCe-selective activator peptide did not. Simi- larly, A61603 shifted the activation curve to the right, whereas Ang Ⅱ had no effect. In addition, both A61603 and PKCα activator peptide showed inhibitory action on bERG A PKC current (an bERG mutant in which 17 of the 18 ROSITE-predicted PKC acceptor serines/threonines were changed to alanine) with a similar potency to wild type bERG current. But, both Ang Ⅱ and PKCe-selective activator peptide exhibited no effects on bERG △ PKC cur- rent. The results indicated that PKCα and PKCe isoforms down-regulated bERG current through different mecha- nism. Conclusion PKCα and PKCe isoform respectively mediates the inhibition on IKr by stimulation of AT1R and alA-AR via different molecular mechanism.
基金Funded by the National Natural Science Foundation of China (No. 62004154)。
文摘The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.
文摘This paper presents a new current conveyor (CCII+) full-wave rectifier for low frequency/small signal medical applications. The proposed rectifier is based on the current conveyor full-wave rectifier proposed previously, but the proposed rectifier is better in view of no need diodes to rectify, and no need bias sources to overcome the zero crossing error. It needs only two CCII+s, two resistors, and three simple current mirrors, which is easy for IC implementation and for building in many countries. The PSPICE simulation with the current conveyor CCII+ in the current feedback opamp AD844 IC and the 2N2222 bipolar current mirror shows the good low frequency/small signal rectification, the operation voltage of down to 6 .
文摘On the basis of detailed analysis of a novel harmonic counteracting method which can be used to effectively compensate the supply line harmonic currents of a passive single phase diode bridge rectifier, this paper presents two simpler single phase diode bridge rectifier configurations and their alternatives which can achieve low supply line current THD(total harmonic distortion) too. Moreover, this paper also proposes a few passive hamonic counteracting networks for multi single phase rectifiers which are connected in parallel.
基金Natural Science Foundation of Gansu Province Education Department(No.2017A-020)National Natural Science Foundation of China(No.51767013)Science and Technology Research and Development Plan of China Railway Corporation(No.2017J012-A)
文摘To solve the input current harmonic pollution of the high power rectifier system,18-pulse rectifier based on a kind of active harmonic suppression technique at dc side is proposed in this paper.The pulse rectifier employs three-phase diode bridges,each of them followed by a boost converter.Unlike the conventional three-phase unity-power-factor diode rectifier,the ideal sinusoidal main currents of circuit topology are obtained by control its output current or input currents of three boost converters for approximately triangular modulation.The theoretical of modulation strategy and characteristics of input and output currents about the proposed rectifier are analyzed in detail.Simulation results by Matlab/Simulink demonstrate that the proposed rectifier draws nearly sinusoidal current and power quality index is improved.The correctness of the theoretical analysis is validated.
基金Project supported by the Program for New Century Excellent Talents in University,China(Grant No.NCET-10-0052)the Fundamental Research Funds for the Central Universities of China(Grant No.HEUCFT1008)
文摘A junction barrier Schottky (JBS) rectifier with an improved P-well on 4H-SiC is proposed to improve the VF-IR trade-off and the breakdown voltage. The reverse current density of the proposed JBS rectifier at 300 K and 800 V is about 3.3 × 10-s times that of the common JBS rectifier at no expense of the forward voltage drop. This is because the depletion layer thickness in the P-well region at the same reverse voltage is larger than in the P+ grid, resulting in a lower spreading current and tunneling current. As a result, the breakdown voltage of the proposed JBS rectifier is over 1.6 kV, that is about 0.8 times more than that of the common JBS rectifier due to the uniform electric field. Although the series resistance of the proposed JBS rectifier is a little larger than that of the common JBS rectifier, the figure of merit (FOM) of the proposed JBS rectifier is about 2.9 times that of the common JBS rectifier. Based on simulating the values of susceptibility of the two JBS rectifiers to electrostatic discharge (ESD) in the human body model (HBM) circuits, the failure energy of the proposed JBS rectifier increases 17% compared with that of the common JBS rectifier.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61874098 and 61974017)the Fundamental Research Project for Central Universities,China(Grant No.ZYGX2018J025).
文摘A robust electron device called the enhanced gated-diode-triggered silicon-controlled rectifier (EGDTSCR) for electrostatic discharge (ESD) protection applications has been proposed and implemented in a 0.18-μm 5-V/24-V BCD process. The proposed EGDTSCR is constructed by adding two gated diodes into a conventional ESD device called the modified lateral silicon-controlled rectifier (MLSCR). With the shunting effect of the surface gated diode path, the proposed EGDTSCR, with a width of 50 μm, exhibits a higher failure current (i.e., 3.82 A) as well as a higher holding voltage (i.e., 10.21 V) than the MLSCR.
文摘电流源型脉宽调制(Pulse width modulation,PWM)整流器因其网侧存在LC滤波器,系统的控制难度增加。传统直接功率控制策略下的整流器功率波形存在脉动,因模型预测控制具有卓越的动态特性以及直观的控制规律,采用模型预测直接功率控制(Model predictive direct power control,MPDPC)对传统控制策略进行改进。首先建立了三相PWM整流器的数学模型,给出了每个采样周期内的功率变化率,并推导出相邻采样周期之间的功率关系,然后给出基于单矢量的模型预测直接功率控制策略,提出了基于双矢量的模型预测直接功率控制策略,并优选出两个电流矢量,计算在一个采样周期内的作用时间,并对其进行修正。最后,在Matlab/Simulink仿真软件验证了所提控制策略的可行性和有效性。