Experimental study on the 4H-SiC-based VDMOSFETs with lightly doped P-well field-limiting rings termination

NASA Astrophysics Data System (ADS)

He, Yan Jing; Lv, Hong Liang; Tang, Xiao Yan; Song, Qing Wen; Zhang, Yi Meng; Han, Chao; Zhang, Yi Men; Zhang, Yu Ming

2017-03-01

A lightly doped P-well field-limiting rings (FLRs) termination on 4H-SiC vertical double-implanted metal-oxide-semiconductor field-effect transistors (VDMOSFETs) has been investigated. Based on the simulation, the proposed termination applied to 4H-SiC VDMOSFET could achieve an almost same breakdown voltage (BV) and have the advantage of lower ion-implantation damage comparing with P+ FLRs termination. Meanwhile, this kind of termination also reduces the difficulty and consumption of fabrication process. 4H-SiC VDMOSFETs with lightly doped P-well (FLRs) termination have been fabricated on 10 μm thick epi-layer with nitrogen doping concentration of 6.2 × 1015 cm-3. The maximum breakdown voltage of the 4H-SiC VDMOSFETs has achieved as high as 1610 V at a current of 15 μA, which is very close to the simulated result of 1643 V and about 90% of the plane parallel breakdown voltage of 1780 V. It is considered that P-well FLRs termination is an effective, robust and process-tolerant termination structure suitable for 4H-SiC VDMOSFET.

Real power regulation design for multi-terminal VSC-HVDC systems

NASA Astrophysics Data System (ADS)

Li, Guo-Jie; Ruan, Si-Ye; Lie, Tek Tjing

2013-06-01

A multi-terminal voltage-source-converter (VSC) based high voltage direct current (HVDC) system is concerned for its flexibility and reliability. In this study, a control strategy for multiple VSCs is proposed to auto-share the real power variation without changing control mode, which is based on "dc voltage droop" power regulation functions. With the proposed power regulation design, the multiple VSCs automatically share the real power change and the VSC-HVDC system is stable even under loss of any one converter while there is no overloading for any individual converter. Simulation results show that it is effective to balance real power for power disturbance and thus improves operation reliability for the multi-terminal VSC-HVDC system by the proposed control strategy.

High ESD Breakdown-Voltage InP HBT Transimpedance Amplifier IC for Optical Video Distribution Systems

NASA Astrophysics Data System (ADS)

Sano, Kimikazu; Nagatani, Munehiko; Mutoh, Miwa; Murata, Koichi

This paper is a report on a high ESD breakdown-voltage InP HBT transimpedance amplifier IC for optical video distribution systems. To make ESD breakdown-voltage higher, we designed ESD protection circuits integrated in the TIA IC using base-collector/base-emitter diodes of InP HBTs and resistors. These components for ESD protection circuits have already existed in the employed InP HBT IC process, so no process modifications were needed. Furthermore, to meet requirements for use in optical video distribution systems, we studied circuit design techniques to obtain a good input-output linearity and a low-noise characteristic. Fabricated InP HBT TIA IC exhibited high human-body-model ESD breakdown voltages (±1000V for power supply terminals, ±200V for high-speed input/output terminals), good input-output linearity (less than 2.9-% duty-cycle-distortion), and low noise characteristic (10.7pA/√Hz averaged input-referred noise current density) with a -3-dB-down higher frequency of 6.9GHz. To the best of our knowledge, this paper is the first literature describing InP ICs with high ESD-breakdown voltages.

Inrush Current Suppression Circuit and Method for Controlling When a Load May Be Fully Energized

NASA Technical Reports Server (NTRS)

Schwerman, Paul (Inventor)

2017-01-01

A circuit and method for controlling when a load may be fully energized includes directing electrical current through a current limiting resistor that has a first terminal connected to a source terminal of a field effect transistor (FET), and a second terminal connected to a drain terminal of the FET. The gate voltage magnitude on a gate terminal of the FET is varied, whereby current flow through the FET is increased while current flow through the current limiting resistor is simultaneously decreased. A determination is made as to when the gate voltage magnitude on the gate terminal is equal to or exceeds a predetermined reference voltage magnitude, and the load is enabled to be fully energized when the gate voltage magnitude is equal to or exceeds the predetermined reference voltage magnitude.

Normally-off AlGaN/GaN-based MOS-HEMT with self-terminating TMAH wet recess etching

NASA Astrophysics Data System (ADS)

Son, Dong-Hyeok; Jo, Young-Woo; Won, Chul-Ho; Lee, Jun-Hyeok; Seo, Jae Hwa; Lee, Sang-Heung; Lim, Jong-Won; Kim, Ji Heon; Kang, In Man; Cristoloveanu, Sorin; Lee, Jung-Hee

2018-03-01

Normally-off AlGaN/GaN-based MOS-HEMT has been fabricated by utilizing damage-free self-terminating tetramethyl ammonium hydroxide (TMAH) recess etching. The device exhibited a threshold voltage of +2.0 V with good uniformity, extremely small hysteresis of ∼20 mV, and maximum drain current of 210 mA/mm. The device also exhibited excellent off-state performances, such as breakdown voltage of ∼800 V with off-state leakage current as low as ∼10-12 A and high on/off current ratio (Ion/Ioff) of 1010. These excellent device performances are believed to be due to the high quality recessed surface, provided by the simple self-terminating TMAH etching.

Catheterized plasma X-ray source

DOEpatents

Derzon, Mark S.; Robinson, Alex; Galambos, Paul C.

2017-06-20

A radiation generator useful for medical applications, among others, is provided. The radiation generator includes a catheter; a plasma discharge chamber situated within a terminal portion of the catheter, a cathode and an anode positioned within the plasma discharge chamber and separated by a gap, and a high-voltage transmission line extensive through the interior of the catheter and terminating on the cathode and anode so as to deliver, in operation, one or more voltage pulses across the gap.

Capacitively-coupled inductive sensors for measurements of pulsed currents and pulsed magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekdahl, C.A.

In experiments involving pulsed high magnetic fields the appearance of the full induced voltage at the output terminals of large-area inductive sensors such as diamagnetic loops and Rogowski belts imposes severe requirements on the insulation near the output. Capacitive detection of the inductive-sensor output voltage provides an ideal geometry for high-voltage insulation, and also accomplishes the necessary voltage division. An inductive-shunt current monitor was designed to utilize the capacitive-detection principle. The contruction of this device and its performance are described in this paper.

Fuel cell system

DOEpatents

Early, Jack; Kaufman, Arthur; Stawsky, Alfred

1982-01-01

A fuel cell system is comprised of a fuel cell module including sub-stacks of series-connected fuel cells, the sub-stacks being held together in a stacked arrangement with cold plates of a cooling means located between the sub-stacks to function as electrical terminals. The anode and cathode terminals of the sub-stacks are connected in parallel by means of the coolant manifolds which electrically connect selected cold plates. The system may comprise a plurality of the fuel cell modules connected in series. The sub-stacks are designed to provide a voltage output equivalent to the desired voltage demand of a low voltage, high current DC load such as an electrolytic cell to be driven by the fuel cell system. This arrangement in conjunction with switching means can be used to drive a DC electrical load with a total voltage output selected to match that of the load being driven. This arrangement eliminates the need for expensive voltage regulation equipment.

Sliding-mode control of single input multiple output DC-DC converter

NASA Astrophysics Data System (ADS)

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. 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, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Sliding-mode control of single input multiple output DC-DC converter.

PubMed

Zhang, Libo; Sun, Yihan; Luo, Tiejian; Wan, Qiyang

2016-10-01

Various voltage levels are required in the vehicle mounted power system. A conventional solution is to utilize an independent multiple output DC-DC converter whose cost is high and control scheme is complicated. In this paper, we design a novel SIMO DC-DC converter with sliding mode controller. 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, which endow the converter with characteristics of simple structure, low cost, and convenient control. In addition, the sliding mode control (SMC) technique applied in our converter can enhance the performances of a certain SIMO DC-DC converter topology. The high-voltage DC bus can be regarded as the main power source to the high-voltage facility of the vehicle mounted power system, and the middle-voltage output terminals can supply power to the low-voltage equipment on an automobile. In the respect of control algorithm, it is the first time to propose the SMC-PID (Proportion Integration Differentiation) control algorithm, in which the SMC algorithm is utilized and the PID control is attended to the conventional SMC algorithm. The PID control increases the dynamic ability of the SMC algorithm by establishing the corresponding SMC surface and introducing the attached integral of voltage error, which endow the sliding-control system with excellent dynamic performance. At last, we established the MATLAB/SIMULINK simulation model, tested performance of the system, and built the hardware prototype based on Digital Signal Processor (DSP). Results show that the sliding mode control is able to track a required trajectory, which has robustness against the uncertainties and disturbances.

Calmodulin and calcium differentially regulate the neuronal Nav1.1 voltage-dependent sodium channel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaudioso, Christelle; Carlier, Edmond; Youssouf, Fahamoe

2011-07-29

Highlights: {yields} Both Ca{sup ++}-Calmodulin (CaM) and Ca{sup ++}-free CaM bind to the C-terminal region of Nav1.1. {yields} Ca{sup ++} and CaM have both opposite and convergent effects on I{sub Nav1.1}. {yields} Ca{sup ++}-CaM modulates I{sub Nav1.1} amplitude. {yields} CaM hyperpolarizes the voltage-dependence of activation, and increases the inactivation rate. {yields} Ca{sup ++} alone antagonizes CaM for both effects, and depolarizes the voltage-dependence of inactivation. -- Abstract: Mutations in the neuronal Nav1.1 voltage-gated sodium channel are responsible for mild to severe epileptic syndromes. The ubiquitous calcium sensor calmodulin (CaM) bound to rat brain Nav1.1 and to the human Nav1.1 channelmore » expressed by a stably transfected HEK-293 cell line. The C-terminal region of the channel, as a fusion protein or in the yeast two-hybrid system, interacted with CaM via a consensus C-terminal motif, the IQ domain. Patch clamp experiments on HEK1.1 cells showed that CaM overexpression increased peak current in a calcium-dependent way. CaM had no effect on the voltage-dependence of fast inactivation, and accelerated the inactivation kinetics. Elevating Ca{sup ++} depolarized the voltage-dependence of fast inactivation and slowed down the fast inactivation kinetics, and for high concentrations this effect competed with the acceleration induced by CaM alone. Similarly, the depolarizing action of calcium antagonized the hyperpolarizing shift of the voltage-dependence of activation due to CaM overexpression. Fluorescence spectroscopy measurements suggested that Ca{sup ++} could bind the Nav1.1 C-terminal region with micromolar affinity.« less

Tailoring highly conductive graphene nanoribbons from small polycyclic aromatic hydrocarbons: a computational study.

PubMed

Bilić, A; Sanvito, S

2013-07-10

Pyrene, the smallest two-dimensional mesh of aromatic rings, with various terminal thiol substitutions, has been considered as a potential molecular interconnect. Charge transport through two terminal devices has been modeled using density functional theory (with and without self interaction correction) and the non-equilibrium Green's function method. A tetra-substituted pyrene, with dual thiol terminal groups at opposite ends, has been identified as an excellent candidate, owing to its high conductance, virtually independent of bias voltage. The two possible extensions of its motif generate two series of graphene nanoribbons, with zigzag and armchair edges and with semimetallic and semiconducting electron band structure, respectively. The effects related to the wire length and the bias voltage on the charge transport have been investigated for both sets. The conductance of the nanoribbons with a zigzag edge does not show either length or voltage dependence, owing to an almost perfect electron transmission with a continuum of conducting channels. In contrast, for the armchair nanoribbons a slow exponential attenuation of the conductance with the length has been found, due to their semiconducting nature.

A dc to dc converter

NASA Astrophysics Data System (ADS)

Willis, A. E.; Gould, J. M.; Matheney, J. L.; Garrett, H.

1984-01-01

The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned.

High voltage MOSFET switching circuit

DOEpatents

McEwan, Thomas E.

1994-01-01

The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET.

Electrocardiographic signal-averaging during atrial pacing and effect of cycle length on the terminal QRS in patients with and without inducible ventricular tachycardia.

PubMed

Kremers, M S; Black, W H; Lange, R; Wells, P J; Solo, M

1990-11-01

Electrocardiographic signal-averaging during sinus rhythm (61 to 99 beats/min) and atrial pacing (100 to 171 beats/min) were performed to determine the effect of heart rate on late potentials in 15 patients without (group 1) and 7 patients with (group 2) inducible sustained ventricular tachycardia (VT). In sinus rhythm (79 +/- 12 vs 77 +/- 12 beats/min, difference not significant), the duration of the low-amplitude signal less than 40 microV was longer in group 2 than group 1 (43 +/- 21 vs 26 +/- 8 ms, p = 0.034) and more patients had late potentials (57 vs 7%, p = 0.021), but QRS duration (121 +/- 32 vs 98 +/- 19 ms) and terminal voltage (33 +/- 33 vs 50 +/- 26 ms) were not significantly different. With atrial pacing in group 1 (128 +/- 16 beats/min), 3 patients developed a simultaneous decrease in terminal voltage and an increase in terminal QRS duration consistent with a late potential, but mean total and terminal durations were unchanged. Terminal voltage increased (50 +/- 26 to 59 +/- 40) but not significantly. With atrial pacing in group 2 (119 +/- 12 beats/min) all patients either had a late potential or developed a simultaneous decrease in terminal voltage and an increase in terminal QRS duration (p = 0.001 vs group 1). Root mean square (p = 0.001 vs group 1). Root mean square voltage decreased (33 +/- 23 to 22 +/- 23) and became significantly different from group 1 (p = 0.017). Mean QRS duration, root mean square terminal voltage and low-amplitude terminal QRS duration, however, were unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved transmission of electrostatic accelerator in a wide range of terminal voltages by controlling the focal strength of entrance acceleration tube

NASA Astrophysics Data System (ADS)

Lobanov, Nikolai R.; Tunningley, Thomas; Linardakis, Peter

2018-04-01

Tandem electrostatic accelerators often require the flexibility to operate at a variety of terminal voltages to accommodate various user requirements. However, the ion beam transmission will only be optimal for a limited range of terminal voltages. This paper describes the operational performance of a novel focusing system that expands the range of terminal voltages for optimal transmission. This is accomplished by controlling the gradient of the entrance of the low-energy tube, providing an additional focusing element. In this specific case it is achieved by applying up to 150 kV to the fifth electrode of the first unit of the accelerator tube. Numerical simulations and beam transmission tests have been performed to confirm the effectiveness of the lens. An analytical expression has been derived describing its focal properties. These tests demonstrate that the entrance lens control eliminates the need to short out sections of the tube for operation at low terminal voltage.

Accelerator mass spectrometer with ion selection in high-voltage terminal

NASA Astrophysics Data System (ADS)

Rastigeev, S. A.; Goncharov, A. D.; Klyuev, V. F.; Konstantinov, E. S.; Kutnyakova, L. A.; Parkhomchuk, V. V.; Petrozhitskii, A. V.; Frolov, A. R.

2016-12-01

The folded electrostatic tandem accelerator with ion selection in a high-voltage terminal is the basis of accelerator mass spectrometry (AMS) at the BINP. Additional features of the BINP AMS are the target based on magnesium vapors as a stripper without vacuum deterioration and a time-of-flight telescope with thin films for reliable ion identification. The acceleration complex demonstrates reliable operation in a mode of 1 MV with 50 Hz counting rate of 14C+3 radiocarbon for modern samples (14C/12C 1.2 × 10-12). The current state of the AMS has been considered and the experimental results of the radiocarbon concentration measurements in test samples have been presented.

Phosphorylation of purified mitochondrial Voltage-Dependent Anion Channel by c-Jun N-terminal Kinase-3 modifies channel voltage-dependence.

PubMed

Gupta, Rajeev; Ghosh, Subhendu

2017-06-01

Voltage-Dependent Anion Channel (VDAC) phosphorylated by c-Jun N-terminal Kinase-3 (JNK3) was incorporated into the bilayer lipid membrane. Single-channel electrophysiological properties of the native and the phosphorylated VDAC were compared. The open probability versus voltage curve of the native VDAC displayed symmetry around the voltage axis, whereas that of the phosphorylated VDAC showed asymmetry. This result indicates that phosphorylation by JNK3 modifies voltage-dependence of VDAC.

47 CFR 80.959 - Radiotelephone transmitter.

Code of Federal Regulations, 2010 CFR

2010-10-01

... watts into 50 ohms nominal resistance when operated with its rated supply voltage. The transmitter must... capability of the transmitter, measurements of primary supply voltage and transmitter output power must be... voltage measured at the power input terminals to the transmitter terminated in a matching artificial load...

Voltage dips at the terminals of wind power installations

NASA Astrophysics Data System (ADS)

Bollen, Math H. J.; Olguin, Gabriel; Martins, Marcia

2005-07-01

This article gives an overview of the kind of voltage dips that can be expected at the terminals of a wind power installation. The overview is based on the study of those dips at the terminals of industrial installations and provides a guideline for the testing of wind power installations against voltage dips. For voltage dips due to faults, a classification into different types is presented. Five types appear at the terminals of sensitive equipment and thus have to be included when testing the wind power installation against disturbances coming from the grid. A distinction is made between installations connected at transmission level and those connected at distribution level. For the latter the phase angle jump has to be considered. Dips due to other causes (motor, transformer and capacitor switching) are briefly discussed as well as the voltage recovery after a dip. Finally some thoughts are presented on the way in which voltage tolerance requirements should be part of the design process for wind power installations. Copyright

High voltage MOSFET switching circuit

DOEpatents

McEwan, T.E.

1994-07-26

The problem of source lead inductance in a MOSFET switching circuit is compensated for by adding an inductor to the gate circuit. The gate circuit inductor produces an inductive spike which counters the source lead inductive drop to produce a rectangular drive voltage waveform at the internal gate-source terminals of the MOSFET. 2 figs.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shepard, Kenneth L.; Sturcken, Noah Andrew

Power controller includes an output terminal having an output voltage, at least one clock generator to generate a plurality of clock signals and a plurality of hardware phases. Each hardware phase is coupled to the at least one clock generator and the output terminal and includes a comparator. Each hardware phase is configured to receive a corresponding one of the plurality of clock signals and a reference voltage, combine the corresponding clock signal and the reference voltage to produce a reference input, generate a feedback voltage based on the output voltage, compare the reference input and the feedback voltage usingmore » the comparator and provide a comparator output to the output terminal, whereby the comparator output determines a duty cycle of the power controller. An integrated circuit including the power controller is also provided.« less

Four-terminal circuit element with photonic core

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sampayan, Stephen

A four-terminal circuit element is described that includes a photonic core inside of the circuit element that uses a wide bandgap semiconductor material that exhibits photoconductivity and allows current flow through the material in response to the light that is incident on the wide bandgap material. The four-terminal circuit element can be configured based on various hardware structures using a single piece or multiple pieces or layers of a wide bandgap semiconductor material to achieve various designed electrical properties such as high switching voltages by using the photoconductive feature beyond the breakdown voltages of semiconductor devices or circuits operated basedmore » on electrical bias or control designs. The photonic core aspect of the four-terminal circuit element provides unique features that enable versatile circuit applications to either replace the semiconductor transistor-based circuit elements or semiconductor diode-based circuit elements.« less

An “ohmic-first” self-terminating gate-recess technique for normally-off Al2O3/GaN MOSFET

NASA Astrophysics Data System (ADS)

Wang, Hongyue; Wang, Jinyan; Li, Mengjun; He, Yandong; Wang, Maojun; Yu, Min; Wu, Wengang; Zhou, Yang; Dai, Gang

2018-04-01

In this article, an ohmic-first AlGaN/GaN self-terminating gate-recess etching technique was demonstrated where ohmic contact formation is ahead of gate-recess-etching/gate-dielectric-deposition (GRE/GDD) process. The ohmic contact exhibits few degradations after the self-terminating gate-recess process. Besides, when comparing with that using the conventional fabrication process, the fabricated device using the ohmic-first fabrication process shows a better gate dielectric quality in terms of more than 3 orders lower forward gate leakage current, more than twice higher reverse breakdown voltage as well as better stability. Based on this proposed technique, the normally-off Al2O3/GaN MOSFET exhibits a threshold voltage (V th) of ˜1.8 V, a maximum drain current of ˜328 mA/mm, a forward gate leakage current of ˜10-6 A/mm and an off-state breakdown voltage of 218 V at room temperature. Meanwhile, high temperature characteristics of the device was also evaluated and small variations (˜7.6%) of the threshold voltage was confirmed up to 300 °C.

Simulation design of high reverse blocking high-K/low-K compound passivation AlGaN/GaN Schottky barrier diode with gated edge termination

NASA Astrophysics Data System (ADS)

Bai, Zhiyuan; Du, Jiangfeng; Xin, Qi; Li, Ruonan; Yu, Qi

2017-11-01

In this paper, a novel high-K/low-K compound passivation AlGaN/GaN Schottky Barrier Diode (CPG-SBD) is proposed to improve the off-state characteristics of AlGaN/GaN schottky barrier diode with gated edge termination (GET-SBD) by adding low-K blocks in to the high-K passivation layer. The reverse leakage current of CPG-SBD can be reduced to 1.6 nA/mm by reducing the thickness of high-K dielectric under GET region to 5 nm, while the forward voltage and on-state resistance keep 1 V and 3.8 Ω mm, respectively. Breakdown voltage of CPG-SBDs can be improved by inducing discontinuity of the electric field at the high-K/low-K interface. The breakdown voltage of the optimized CPG-SBD with 4 blocks of low-K can reach 1084 V with anode to cathode distance of 5 μm yielding a high FOM of 5.9 GW/cm2. From the C-V simulation results, CPG-SBDs induce no parasitic capacitance by comparison of the GET-SBDs.

The performance of cable braids and terminations to lightning induced transients

NASA Technical Reports Server (NTRS)

Crofts, David

1991-01-01

The latest specification detailing the test waveforms for indirect lightning transients as applied to aircraft wiring systems specify very high voltages and currents. Although considerable data exists for measuring cable screen leakage using such methods as surface transfer impedance and bulk cable injection, there is little data on the likely core transient level that is likely to be induced from these threats. In particular, the new Waveform 5 at very high current levels (10 kA) is reputed to cause severe cable damage. A range of representative cables were made with various screen termination techniques and screening levels. These were tested first to determine their relative screening performance and then they were subjected to lightning transient testing to all the specified waveforms. Core voltages were measured for each test. Tests were also performed on bundles with fewer wires to determine the failure criteria with Waveform 5 and these tests also include flat conductor cables. The test showed that correctly terminated cable bundles performed well in all the tests and would provide a high level of protection to the electronic systems. The use of overbraides, provided the individual screens are well terminated, appears to be unnecessary.

Fast-responding short circuit protection system with self-reset for use in circuit supplied by DC power

NASA Technical Reports Server (NTRS)

Burns, Bradley M. (Inventor); Blalock, Norman N. (Inventor)

2011-01-01

A short circuit protection system includes an inductor, a switch, a voltage sensing circuit, and a controller. The switch and inductor are electrically coupled to be in series with one another. A voltage sensing circuit is coupled across the switch and the inductor. A controller, coupled to the voltage sensing circuit and the switch, opens the switch when a voltage at the output terminal of the inductor transitions from above a threshold voltage to below the threshold voltage. The controller closes the switch when the voltage at the output terminal of the inductor transitions from below the threshold voltage to above the threshold voltage.

Bidirectional buck boost converter

DOEpatents

Esser, Albert Andreas Maria

1998-03-31

A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero.

Bidirectional buck boost converter

DOEpatents

Esser, A.A.M.

1998-03-31

A bidirectional buck boost converter and method of operating the same allows regulation of power flow between first and second voltage sources in which the voltage level at each source is subject to change and power flow is independent of relative voltage levels. In one embodiment, the converter is designed for hard switching while another embodiment implements soft switching of the switching devices. In both embodiments, first and second switching devices are serially coupled between a relatively positive terminal and a relatively negative terminal of a first voltage source with third and fourth switching devices serially coupled between a relatively positive terminal and a relatively negative terminal of a second voltage source. A free-wheeling diode is coupled, respectively, in parallel opposition with respective ones of the switching devices. An inductor is coupled between a junction of the first and second switching devices and a junction of the third and fourth switching devices. Gating pulses supplied by a gating circuit selectively enable operation of the switching devices for transferring power between the voltage sources. In the second embodiment, each switching device is shunted by a capacitor and the switching devices are operated when voltage across the device is substantially zero. 20 figs.

Static power reduction for midpoint-terminated busses

DOEpatents

Coteus, Paul W [Yorktown Heights, NY; Takken, Todd [Brewster, NY

2011-01-18

A memory system is disclosed which is comprised of a memory controller and addressable memory devices such as DRAMs. The invention provides a programmable register to control the high vs. low drive state of each bit of a memory system address and control bus during periods of bus inactivity. In this way, termination voltage supply current can be minimized, while permitting selected bus bits to be driven to a required state. This minimizes termination power dissipation while not affecting memory system performance. The technique can be extended to work for other high-speed busses as well.

Graded junction termination extensions for electronic devices

NASA Technical Reports Server (NTRS)

Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

2006-01-01

A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

Graded junction termination extensions for electronic devices

NASA Technical Reports Server (NTRS)

Merrett, J. Neil (Inventor); Isaacs-Smith, Tamara (Inventor); Sheridan, David C. (Inventor); Williams, John R. (Inventor)

2007-01-01

A graded junction termination extension in a silicon carbide (SiC) semiconductor device and method of its fabrication using ion implementation techniques is provided for high power devices. The properties of silicon carbide (SiC) make this wide band gap semiconductor a promising material for high power devices. This potential is demonstrated in various devices such as p-n diodes, Schottky diodes, bipolar junction transistors, thyristors, etc. These devices require adequate and affordable termination techniques to reduce leakage current and increase breakdown voltage in order to maximize power handling capabilities. The graded junction termination extension disclosed is effective, self-aligned, and simplifies the implementation process.

Dual-junction GaAs solar cells and their application to smart stacked III–V//Si multijunction solar cells

NASA Astrophysics Data System (ADS)

Sugaya, Takeyoshi; Tayagaki, Takeshi; Aihara, Taketo; Makita, Kikuo; Oshima, Ryuji; Mizuno, Hidenori; Nagato, Yuki; Nakamoto, Takashi; Okano, Yoshinobu

2018-05-01

We report high-quality dual-junction GaAs solar cells grown using solid-source molecular beam epitaxy and their application to smart stacked III–V//Si quadruple-junction solar cells with a two-terminal configuration for the first time. A high open-circuit voltage of 2.94 eV was obtained in an InGaP/GaAs/GaAs triple-junction top cell that was stacked to a Si bottom cell. The short-circuit current density of a smart stacked InGaP/GaAs/GaAs//Si solar cell was in good agreement with that estimated from external quantum efficiency measurements. An efficiency of 18.5% with a high open-circuit voltage of 3.3 V was obtained in InGaP/GaAs/GaAs//Si two-terminal solar cells.

Development and fabrication of low ON resistance high current vertical VMOS power FETs

NASA Technical Reports Server (NTRS)

Kay, S.

1979-01-01

The design of a VMOS Power FET exhibiting low ON resistance, high current as well as high breakdown voltage and fast switching speeds is described. The design which is based on a 1st-order device model, features a novel polysilicon-gate structure and fieldplated groove termination to achieve high packing density and high breakdown voltage, respectively. One test chip, named VNTKI, can block 180 V at an ON resistence of 2.5 ohm. A 150 mil x 200 mil (.19 sq cm) experimental chip has demonstrated a breakdown voltage of 200v, an ON resistance of 0.12 ohm, a switching time of less than 100 ns, and a pulse drain - current of 50 A with 10 V gate drive.

Development and fabrication of a high current, fast recovery power diode

NASA Technical Reports Server (NTRS)

Berman, A. H.; Balodis, V.; Devance, D. C.; Gaugh, C. E.; Karlsson, E. A.

1983-01-01

A high voltage (VR = 1200 V), high current (IF = 150 A), fast recovery ( 700 ns) and low forward voltage drop ( 1.5 V) silicon rectifier was designed and the process developed for its fabrication. For maximum purity, uniformity and material characteristic stability, neutron transmutation n-type doped float zone silicon is used. The design features a hexagonal chip for maximum area utilization of space available in the DO-8 diode package, PIN diffused junction structure with deep diffused D(+) anode and a shallow high concentration n(+) cathode. With the high temperature glass passivated positive bevel mesa junction termination, the achieved blocking voltage is close to the theoretical limit of the starting material. Gold diffusion is used to control the lifetime and the resulting effect on switching speed and forward voltage tradeoff. For solder reflow assembly, trimetal (Al-Ti-Ni) contacts are used. The required major device electrical characteristics were achieved. Due to the tradeoff nature of forward voltage drop and reverse recovery time, a compromise was reached for these values.

Development and application of network virtual instrument for emission spectrum of pulsed high-voltage direct current discharge

NASA Astrophysics Data System (ADS)

Gong, X.; Wu, Q.

2017-12-01

Network virtual instrument (VI) is a new development direction in current automated test. Based on LabVIEW, the software and hardware system of VI used for emission spectrum of pulsed high-voltage direct current (DC) discharge is developed and applied to investigate pulsed high-voltage DC discharge of nitrogen. By doing so, various functions are realized including real time collection of emission spectrum of nitrogen, monitoring operation state of instruments and real time analysis and processing of data. By using shared variables and DataSocket technology in LabVIEW, the network VI system based on field VI is established. The system can acquire the emission spectrum of nitrogen in the test site, monitor operation states of field instruments, realize real time face-to-face interchange of two sites, and analyze data in the far-end from the network terminal. By employing the network VI system, the staff in the two sites acquired the same emission spectrum of nitrogen and conducted the real time communication. By comparing with the previous results, it can be seen that the experimental data obtained by using the system are highly precise. This implies that the system shows reliable network stability and safety and satisfies the requirements for studying the emission spectrum of pulsed high-voltage discharge in high-precision fields or network terminals. The proposed architecture system is described and the target group gets the useful enlightenment in many fields including engineering remote users, specifically in control- and automation-related tasks.

High voltage electrical amplifier having a short rise time

DOEpatents

Christie, David J.; Dallum, Gregory E.

1991-01-01

A circuit, comprising an amplifier and a transformer is disclosed that produces a high power pulse having a fast response time, and that responds to a digital control signal applied through a digital-to-analog converter. The present invention is suitable for driving a component such as an electro-optic modulator with a voltage in the kilovolt range. The circuit is stable at high frequencies and during pulse transients, and its impedance matching circuit matches the load impedance with the output impedance. The preferred embodiment comprises an input stage compatible with high-speed semiconductor components for amplifying the voltage of the input control signal, a buffer for isolating the input stage from the output stage; and a plurality of current amplifiers connected to the buffer. Each current amplifier is connected to a field effect transistor (FET), which switches a high voltage power supply to a transformer which then provides an output terminal for driving a load. The transformer comprises a plurality of transmission lines connected to the FETs and the load. The transformer changes the impedance and voltage of the output. The preferred embodiment also comprises a low voltage power supply for biasing the FETs at or near an operational voltage.

Complementary Paired G4FETs as Voltage-Controlled NDR Device

NASA Technical Reports Server (NTRS)

Mojarradi, Mohammad; Chen, Suheng; Blalock, Ben; Britton, Chuck; Prothro, Ben; Vandersand, James; Schrimph, Ron; Cristoloveanu, Sorin; Akavardar, Kerem; Gentil, P.

2009-01-01

It is possible to synthesize a voltage-controlled negative-differential-resistance (NDR) device or circuit by use of a pair of complementary G4FETs (four-gate field-effect transistors). [For more information about G4FETs, please see the immediately preceding article]. As shown in Figure 1, the present voltage-controlled NDR device or circuit is an updated version of a prior NDR device or circuit, known as a lambda diode, that contains a pair of complementary junction field-effect transistors (JFETs). (The lambda diode is so named because its current-versus- voltage plot bears some resemblance to an upper-case lambda.) The present version can be derived from the prior version by substituting G4FETs for the JFETs and connecting both JFET gates of each G4FET together. The front gate terminals of the G4FETs constitute additional terminals (that is, terminals not available in the older JFET version) to which one can apply control voltages VN and VP. Circuits in which NDR devices have been used include (1) Schmitt triggers and (2) oscillators containing inductance/ capacitance (LC) resonant circuits. Figure 2 depicts such circuits containing G4FET NDR devices like that of Figure 1. In the Schmitt trigger shown here, the G4FET NDR is loaded with an ordinary inversion-mode, p-channel, metal oxide/semiconductor field-effect transistor (inversion-mode PMOSFET), the VN terminal of the G4FET NDR device is used as an input terminal, and the input terminals of the PMOSFET and the G4FET NDR device are connected. VP can be used as an extra control voltage (that is, a control voltage not available in a typical prior Schmitt trigger) for adjusting the pinch-off voltage of the p-channel G4FET and thereby adjusting the trigger-voltage window. In the oscillator, a G4FET NDR device is loaded with a conventional LC tank circuit. As in other LC NDR oscillators, oscillation occurs because the NDR counteracts the resistance in the tank circuit. The advantage of this G4FET-NDR LC oscillator over a conventional LC NDR oscillator is that one can apply a time-varying signal to one of the extra control input terminals (VN or VP) to modulate the conductance of the NDR device and thereby amplitude-modulate the output signal.

An Adaptive Coordinated Control for an Offshore Wind Farm Connected VSC Based Multi-Terminal DC Transmission System

NASA Astrophysics Data System (ADS)

Kumar, M. Ajay; Srikanth, N. V.

2015-01-01

The voltage source converter (VSC) based multiterminal high voltage direct current (MTDC) transmission system is an interesting technical option to integrate offshore wind farms with the onshore grid due to its unique performance characteristics and reduced power loss via extruded DC cables. In order to enhance the reliability and stability of the MTDC system, an adaptive neuro fuzzy inference system (ANFIS) based coordinated control design has been addressed in this paper. A four terminal VSC-MTDC system which consists of an offshore wind farm and oil platform is implemented in MATLAB/ SimPowerSystems software. The proposed model is tested under different fault scenarios along with the converter outage and simulation results show that the novel coordinated control design has great dynamic stabilities and also the VSC-MTDC system can supply AC voltage of good quality to offshore loads during the disturbances.

Ultra-low voltage and ultra-low power consumption nonvolatile operation of a three-terminal atomic switch.

PubMed

Wang, Qi; Itoh, Yaomi; Tsuruoka, Tohru; Aono, Masakazu; Hasegawa, Tsuyoshi

2015-10-21

Nonvolatile three-terminal operation, with a very small range of bias sweeping (-80 to 250 mV), a high on/off ratio of up to six orders of magnitude, and a very small gate leakage current (<1 pA), is demonstrated using an Ag (gate)/Ta2 O5 (ionic transfer layer)/Pt (source), Pt (drain) three-terminal atomic switch structure. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radio-frequency powered glow discharge device and method with high voltage interface

DOEpatents

Duckworth, D.C.; Marcus, R.K.; Donohue, D.L.; Lewis, T.A.

1994-06-28

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components. 11 figures.

Radio-frequency powered glow discharge device and method with high voltage interface

DOEpatents

Duckworth, Douglas C.; Marcus, R. Kenneth; Donohue, David L.; Lewis, Trousdale A.

1994-01-01

A high voltage accelerating potential, which is supplied by a high voltage direct current power supply, is applied to the electrically conducting interior wall of an RF powered glow discharge cell. The RF power supply desirably is electrically grounded, and the conductor carrying the RF power to the sample held by the probe is desirably shielded completely excepting only the conductor's terminal point of contact with the sample. The high voltage DC accelerating potential is not supplied to the sample. A high voltage capacitance is electrically connected in series between the sample on the one hand and the RF power supply and an impedance matching network on the other hand. The high voltage capacitance isolates the high DC voltage from the RF electronics, while the RF potential is passed across the high voltage capacitance to the plasma. An inductor protects at least the RF power supply, and desirably the impedance matching network as well, from a short that might occur across the high voltage capacitance. The discharge cell and the probe which holds the sample are configured and disposed to prevent the probe's components, which are maintained at ground potential, from bridging between the relatively low vacuum region in communication with the glow discharge maintained within the cell on the one hand, and the relatively high vacuum region surrounding the probe and cell on the other hand. The probe and cell also are configured and disposed to prevent the probe's components from electrically shorting the cell's components.

Estimation of Supercapacitor Energy Storage Based on Fractional Differential Equations.

PubMed

Kopka, Ryszard

2017-12-22

In this paper, new results on using only voltage measurements on supercapacitor terminals for estimation of accumulated energy are presented. For this purpose, a study based on application of fractional-order models of supercapacitor charging/discharging circuits is undertaken. Parameter estimates of the models are then used to assess the amount of the energy accumulated in supercapacitor. The obtained results are compared with energy determined experimentally by measuring voltage and current on supercapacitor terminals. All the tests are repeated for various input signal shapes and parameters. Very high consistency between estimated and experimental results fully confirm suitability of the proposed approach and thus applicability of the fractional calculus to modelling of supercapacitor energy storage.

A method for encapsulating high voltage power transformers

NASA Astrophysics Data System (ADS)

Sanchez, Robert O.

Voltage breakdowns become a major concern in reducing the size of high-voltage power converter transformers. Even the smallest of voids can provide a path for corona discharge which can cause a dielectric breakdown leading to a transformer failure. A method of encapsulating small high voltage transformers has been developed. The method virtually eliminates voids in the impregnation material, provides an exceptional dielectric between windings and provides a mechanically rugged package. The encapsulation material is a carboxyl terminated butadiene nitril (CTBN) modified mica filled epoxy. The method requires heat/vacuum to impregnate the coil and heat/pressure to cure the encapsulant. The transformer package utilizes a diallyl phthalate (DAP) contact assembly in which a coated core/coil assembly is mounted and soldered. This assembly is then loaded into an RTV mold and the encapsulation process begins.

Ablation of Persistent Atrial Fibrillation Targeting Low-Voltage Areas With Selective Activation Characteristics.

PubMed

Jadidi, Amir S; Lehrmann, Heiko; Keyl, Cornelius; Sorrel, Jérémie; Markstein, Viktor; Minners, Jan; Park, Chan-Il; Denis, Arnaud; Jaïs, Pierre; Hocini, Mélèze; Potocnik, Clemens; Allgeier, Juergen; Hochholzer, Willibald; Herrera-Sidloky, Claudia; Kim, Steve; Omri, Youssef El; Neumann, Franz-Josef; Weber, Reinhold; Haïssaguerre, Michel; Arentz, Thomas

2016-03-01

Complex-fractionated atrial electrograms and atrial fibrosis are associated with maintenance of persistent atrial fibrillation (AF). We hypothesized that pulmonary vein isolation (PVI) plus ablation of selective atrial low-voltage sites may be more successful than PVI only. A total of 85 consecutive patients with persistent AF underwent high-density atrial voltage mapping, PVI, and ablation at low-voltage areas (LVA < 0.5 mV in AF) associated with electric activity lasting > 70% of AF cycle length on a single electrode (fractionated activity) or multiple electrodes around the circumferential mapping catheter (rotational activity) or discrete rapid local activity (group I). The procedural end point was AF termination. Arrhythmia freedom was compared with a control group (66 patients) undergoing PVI only (group II). PVI alone was performed in 23 of 85 (27%) patients of group I with low amount (< 10% of left atrial surface area) of atrial low voltage. Selective atrial ablation in addition to PVI was performed in 62 patients with termination of AF in 45 (73%) after 11 ± 9 minutes radiofrequency delivery. AF-termination sites colocalized within LVA in 80% and at border zones in 20%. Single-procedural arrhythmia freedom at 13 months median follow-up was achieved in 59 of 85 (69%) patients in group I, which was significantly higher than the matched control group (31/66 [47%], P < 0.001). There was no significant difference in the success rate of patients in group I with a low amount of low voltage undergoing PVI only and patients requiring PVI+selective low-voltage ablation (P = 0.42). Ablation of sites with distinct activation characteristics within/at borderzones of LVA in addition to PVI is more effective than conventional PVI-only strategy for persistent AF. PVI only seems to be sufficient to treat patients with left atrial low voltage < 10%. © 2016 American Heart Association, Inc.

Inhibitory actions of synthesised polyamine spider toxins and their analogues on Ca2+-activated Cl- currents recorded from cultured DRG neurones from neonatal rats.

PubMed

Sutton, K G; Stapleton, S R; Scott, R H

1998-07-24

The whole cell variant of the patch clamp technique was used to investigate the actions of polyamine spider toxins and their analogues on high voltage-activated Ca2+ currents and Ca2+-activated Cl- currents (I(Cl(Ca))). The actions of synthesised FTX (putative natural toxin from the American funnel web spider), sFTX-3.3, Orn-FTX-3.3, Lys-FTX-3.3, and argiotoxin-636 on cultured dorsal root ganglion neurones from neonatal rats were investigated. Synthesised FTX (1 microM) inhibited I(Cl(Ca)) but did not inhibit high voltage-activated Ca2+ currents. In contrast, sFTX-3.3 (10 microM) inhibited both high voltage-activated Ca2+ currents and the associated I(Cl(Ca)) in near equal proportions. Argiotoxin-636 (1-10 microM) inhibited I(Cl(Ca)) evoked by Ca2+ entry through voltage-activated channels and by intracellular photorelease of Ca2+ from a caged precursor DM-nitrophen. This data indicates that synthesised FTX and argiotoxin-636 directly inhibit Ca2+-activated Cl- channels. In conclusion, the potency of polyamines as non-selective inhibitors of Ca2+ channels and Ca2+-activated Cl- channels is in part determined by the presence of a terminal arginine and this may involve an interaction between terminal guanidino groups and Ca2+ binding sites.

An impedance bridge measuring the capacitance ratio in the high frequency range up to 1 MHz

NASA Astrophysics Data System (ADS)

Bee Kim, Dan; Kew Lee, Hyung; Kim, Wan-Seop

2017-02-01

This paper describes a 2-terminal-pair impedance bridge, measuring the capacitance ratio in the high frequency range up to 1 MHz. The bridge was configured with two voltage sources and a phase control unit which enabled the bridge balance by synchronizing the voltage sources with an enhanced phase resolution. Without employing the transformers such as inductive voltage divider, injection and detection transformers, etc, the bridge system is quite simple to set up, and the balance procedure is quick and easy. Using this dual-source coaxial bridge, the 1:1 and 10:1 capacitance ratios were measured with 1 pF-1 nF capacitors in the frequency range from 1 kHz to 1 MHz. The measurement values obtained by the dual-source bridge were then compared with reference values measured using a commercial precision capacitance bridge of AH2700A, the Z-matrix method developed by ourselves, and the 4-terminal-pair coaxial bridge by the Czech Metrological Institute. All the measurements agreed within the reference uncertainty range of an order of 10-6-10-5, proving the bridge ability as a trustworthy tool for measuring the capacitance ratio in the high frequency range.

Numerical analysis of the reverse blocking enhancement in High-K passivation AlGaN/GaN Schottky barrier diodes with gated edge termination

NASA Astrophysics Data System (ADS)

Bai, Zhiyuan; Du, Jiangfeng; Xin, Qi; Li, Ruonan; Yu, Qi

2018-02-01

We conducted a numerical analysis on high-K dielectric passivated AlGaN/GaN Schottky barrier diodes (HPG-SBDs) with a gated edge termination (GET). The reverse blocking characteristics were significantly enhanced without the stimulation of any parasitic effect by varying the dielectric thickness dge under the GET, thickness TP, and dielectric constant εr of the high-K passivation layer. The leakage current was reduced by increasing εr and decreasing dge. The breakdown voltage of the device was enhanced by increasing εr and TP. The highest breakdown voltage of 970 V and the lowest leakage current of 0.5 nA/mm were achieved under the conditions of εr = 80, TP = 800 nm, and dge = 10 nm. C-V simulation revealed that the HPG-SBDs induced no parasitic capacitance by comparing the integrated charges of the devices with different high-K dielectrics and different dge.

Aptamer-Based Carboxyl-Terminated Nanocrystalline Diamond Sensing Arrays for Adenosine Triphosphate Detection

PubMed Central

Suaebah, Evi; Naramura, Takuro; Myodo, Miho; Hasegawa, Masataka; Shoji, Shuichi; Buendia, Jorge J.; Kawarada, Hiroshi

2017-01-01

Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP) detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD). Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and fluorine termination of the background region as a passivated layer were investigated by X-ray photoelectron spectroscopy. Single strand DNA (amide modification) was used as the supporting biomolecule to immobilize into the diamond surface via carboxyl termination and become a double strand with aptamer. ATP detection by aptamer was observed as a 66% fluorescence signal intensity decrease of the hybridization intensity signal. The sensor operation was also investigated by the field-effect characteristics. The shift of the drain current–drain voltage characteristics was used as the indicator for detection of ATP. From the field-effect characteristics, the shift of the drain current–drain voltage was observed in the negative direction. The negative charge direction shows that the aptamer is capable of detecting ATP. The ability of the sensor to detect ATP was investigated by fabricating a field-effect transistor on the modified NCD surface. PMID:28753998

Aptamer-Based Carboxyl-Terminated Nanocrystalline Diamond Sensing Arrays for Adenosine Triphosphate Detection.

PubMed

Suaebah, Evi; Naramura, Takuro; Myodo, Miho; Hasegawa, Masataka; Shoji, Shuichi; Buendia, Jorge J; Kawarada, Hiroshi

2017-07-21

Here, we propose simple diamond functionalization by carboxyl termination for adenosine triphosphate (ATP) detection by an aptamer. The high-sensitivity label-free aptamer sensor for ATP detection was fabricated on nanocrystalline diamond (NCD). Carboxyl termination of the NCD surface by vacuum ultraviolet excimer laser and fluorine termination of the background region as a passivated layer were investigated by X-ray photoelectron spectroscopy. Single strand DNA (amide modification) was used as the supporting biomolecule to immobilize into the diamond surface via carboxyl termination and become a double strand with aptamer. ATP detection by aptamer was observed as a 66% fluorescence signal intensity decrease of the hybridization intensity signal. The sensor operation was also investigated by the field-effect characteristics. The shift of the drain current-drain voltage characteristics was used as the indicator for detection of ATP. From the field-effect characteristics, the shift of the drain current-drain voltage was observed in the negative direction. The negative charge direction shows that the aptamer is capable of detecting ATP. The ability of the sensor to detect ATP was investigated by fabricating a field-effect transistor on the modified NCD surface.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, Jr., Troy W.; Johnson, Gary W.; O'Brien, Dennis W.

1995-01-01

A high performance capacitor fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a "notepad" configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The "notepad" capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, Jr., Troy W.; Johnson, Gary W.; O'Brien, Dennis W.

1996-01-01

A high performance capacitor fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a "notepad" configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The "notepad" capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density.

Overload protection circuit for output driver

DOEpatents

Stewart, Roger G.

1982-05-11

A protection circuit for preventing excessive power dissipation in an output transistor whose conduction path is connected between a power terminal and an output terminal. The protection circuit includes means for sensing the application of a turn on signal to the output transistor and the voltage at the output terminal. When the turn on signal is maintained for a period of time greater than a given period without the voltage at the output terminal reaching a predetermined value, the protection circuit decreases the turn on signal to, and the current conduction through, the output transistor.

Logarithmic circuit with wide dynamic range

NASA Technical Reports Server (NTRS)

Wiley, P. H.; Manus, E. A. (Inventor)

1978-01-01

A circuit deriving an output voltage that is proportional to the logarithm of a dc input voltage susceptible to wide variations in amplitude includes a constant current source which forward biases a diode so that the diode operates in the exponential portion of its voltage versus current characteristic, above its saturation current. The constant current source includes first and second, cascaded feedback, dc operational amplifiers connected in negative feedback circuit. An input terminal of the first amplifier is responsive to the input voltage. A circuit shunting the first amplifier output terminal includes a resistor in series with the diode. The voltage across the resistor is sensed at the input of the second dc operational feedback amplifier. The current flowing through the resistor is proportional to the input voltage over the wide range of variations in amplitude of the input voltage.

High Voltage Discharge Profile on Soil Breakdown Using Impulse Discharge

NASA Astrophysics Data System (ADS)

Fajingbesi, F. E.; Midi, N. S.; Elsheikh, E. M. A.; Yusoff, S. H.

2017-06-01

Grounding terminals are mandatory in electrical appliance design as they provide safety route during overvoltage faults. The soil (earth) been the universal ground is assumed to be at zero electric potential. However, due to properties like moisture, pH and available nutrients; the electric potential may fluctuate between positive and negative values that could be harmful for internally connected circuits on the grounding terminal. Fluctuations in soil properties may also lead to current crowding effect similar to those seen at the emitters of semiconductor transistors. In this work, soil samples are subjected to high impulse voltage discharge and the breakdown characteristics was profiled. The results from profiling discharge characteristics of soil in this work will contribute to the optimization of grounding protection system design in terms of electrode placement. This would also contribute to avoiding grounding electrode current crowding, ground potential rise fault and electromagnetic coupling faults.

Method and apparatus for monitoring the rotating frequency of de-energized induction motors

DOEpatents

Mikesell, H.E.; Lucy, E.

1998-02-03

The rotational speed of a coasting induction motor is measured by sensing e residual electrical voltages at the power terminals of the motor, thus eliminating the need for conventional tachometer equipment, additional mechanical components or modifications to the induction motor itself. The power terminal voltage signal is detected and transformed into a DC voltage proportional to the frequency of the signal. This DC voltage can be input to the control system of a variable frequency motor controller to regulate the output characteristics thereof relative to the speed of the coasting motor. 6 figs.

Method and apparatus for monitoring the rotating frequency of de-energized induction motors

DOEpatents

Mikesell, Harvey E.; Lucy, Eric

1998-01-01

The rotational speed of a coasting induction motor is measured by sensing e residual electrical voltages at the power terminals of the motor, thus eliminating the need for conventional tachometer equipment, additional mechanical components or modifications to the induction motor itself. The power terminal voltage signal is detected and transformed into a DC voltage proportional to the frequency of the signal. This DC voltage can be input to the control system of a variable frequency motor controller to regulate the output characteristics thereof relative to the speed of the coasting motor.

Short-Term Facilitation at a Detonator Synapse Requires the Distinct Contribution of Multiple Types of Voltage-Gated Calcium Channels.

PubMed

Chamberland, Simon; Evstratova, Alesya; Tóth, Katalin

2017-05-10

Neuronal calcium elevations are shaped by several key parameters, including the properties, density, and the spatial location of voltage-gated calcium channels (VGCCs). These features allow presynaptic terminals to translate complex firing frequencies and tune the amount of neurotransmitter released. Although synchronous neurotransmitter release relies on both P/Q- and N-type VGCCs at hippocampal mossy fiber-CA3 synapses, the specific contribution of VGCCs to calcium dynamics, neurotransmitter release, and short-term facilitation remains unknown. Here, we used random-access two-photon calcium imaging together with electrophysiology in acute mouse hippocampal slices to dissect the roles of P/Q- and N-type VGCCs. Our results show that N-type VGCCs control glutamate release at a limited number of release sites through highly localized Ca 2+ elevations and support short-term facilitation by enhancing multivesicular release. In contrast, Ca 2+ entry via P/Q-type VGCCs promotes the recruitment of additional release sites through spatially homogeneous Ca 2+ elevations. Altogether, our results highlight the specialized contribution of P/Q- and N-types VGCCs to neurotransmitter release. SIGNIFICANCE STATEMENT In presynaptic terminals, neurotransmitter release is dynamically regulated by the transient opening of different types of voltage-gated calcium channels. Hippocampal giant mossy fiber terminals display extensive short-term facilitation during repetitive activity, with a large several fold postsynaptic response increase. Though, how giant mossy fiber terminals leverage distinct types of voltage-gated calcium channels to mediate short-term facilitation remains unexplored. Here, we find that P/Q- and N-type VGCCs generate different spatial patterns of calcium elevations in giant mossy fiber terminals and support short-term facilitation through specific participation in two mechanisms. Whereas N-type VGCCs contribute only to the synchronization of multivesicular release, P/Q-type VGCCs act through microdomain signaling to recruit additional release sites. Copyright © 2017 the authors 0270-6474/17/374913-15$15.00/0.

Accelerator characterization of the new ion beam facility at MTA Atomki in Debrecen, Hungary

NASA Astrophysics Data System (ADS)

Rajta, I.; Vajda, I.; Gyürky, Gy.; Csedreki, L.; Kiss, Á. Z.; Biri, S.; van Oosterhout, H. A. P.; Podaru, N. C.; Mous, D. J. W.

2018-02-01

In this work we present the 2 MV Tandetron accelerator manufactured by High Voltage Engineering Europa (HVEE), that was installed at MTA Atomki in Debrecen, Hungary in 2015. Furthermore, we report on the first performance test of the whole facility including the calibration of the terminal voltage using accurately known resonance energies of the 27Al(p, γ)28Si and 13C(p, γ)14N reactions, as well as neutron threshold energies of the 7Li(p,n)7Be and 13C(p,n)13N reactions. The accurate energy calibration of the generating voltmeter (GVM), the good energy stability of the accelerator as well as the low energy spread of the ion beam suited the requirements of nuclear astrophysics, resonance PIGE depth profiling and the nanoprobe beamline. We have investigated whether the terminal voltage reading depends on the insulating gas pressure, and how much the stripper gas pressure modifies the beam energy.

Design, fabrication, and characterization of 4H-silicon carbide rectifiers for power switching applications

NASA Astrophysics Data System (ADS)

Sheridan, David Charles

Silicon Carbide has received a substantial increase in research interest over the past few years as a base material system for high-frequency and high-power semiconductor devices. Of the over 1200 polytypes, 4H-SiC is the most attractive polytype for power devices due to its wide band gap (3.2eV), excellent thermal conductivity (4.9 W/cm·K), and high critical field strength (˜2 x 106 V/cm). Important for power devices, the 10x increase in critical field strength of SiC allows high voltage blocking layers to be fabricated significantly thinner than for comparable Si devices. For power rectifiers, this reduces device on-resistance, while maintaining the same high voltage blocking capability. In this work, 4H-SiC Schottky, pn, and junction barrier Schottky (JBS) rectifiers for use in high voltage switching applications have been designed, fabricated, and extensively characterized. First, a detailed review of 4H-SiC material parameters was performed and SiC models were implemented into a standard Si drift-diffusion numerical simulator. Using these models, a SiC simulation methodology was developed in order to enable predictive SiC device design. A wide variety of rectifier and edge termination designs were investigated and optimized with respect to breakdown efficiency, area consumption, resistance to interface charge, and fabrication practicality. Simulated termination methods include: field plates, floating guard rings, and a variety of junction termination extensions (JTE). Using the device simulation results, both Schottky and JBS rectifiers were fabricated with a novel self-aligned edge termination design, and fabricated with process elements developed at the Alabama Microelectronics Science and Technology Center facility. These rectifiers exhibited near-ideal forward characteristics and had blocking voltages in excess of 2.5kV. The SiC diodes were subjected to inductive switching tests, and were found to have superior reverse recovery characteristics compared to a similar Si diode. Finally, the performance of these SiC rectifiers were tested in inductive switching circuits and in high dose gamma radiation environments. In both cases, these devices were shown to be superior to their silicon counterparts. The details of this work was presented and published in the proceedings of the 45th International Meeting of the American Vacuum Society [1], the 1999 International Conference on Silicon Carbide and Related Materials [2, 3] and the 2000 European Conference on Silicon Carbide and Related Materials [4]. The expanded conference papers were published in the international journal. Solid-State Electronics [5, 6].

Charge control microcomputer device for vehicle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morishita, M.; Kouge, S.

1986-08-26

A charge control microcomputer device is described for a vehicle, comprising: an AC generator driven by an engine for generating an output current, the generator having armature coils and a field coil; a battery charged by a rectified output of the generator and generating a terminal voltage; a voltage regulator for controlling a current flowing in the field coil, to control an output voltage of the generator to a predetermined value; an engine controlling microcomputer for receiving engine parameter data from the engine, to control the operation of the engine; a charge control microcomputer for processing input data including datamore » on at least one engine parameter output from the engine controlling microcomputer, and charge system data including at least one of battery terminal voltage data, generator voltage data and generator output current data, to provide a reference voltage for the voltage regulator.« less

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

1995-05-09

A high performance capacitor is fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a ``notepad`` configuration composed of 200-300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The notepad capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density. 5 figs.

High performance capacitors using nano-structure multilayer materials fabrication

DOEpatents

Barbee, T.W. Jr.; Johnson, G.W.; O`Brien, D.W.

1996-01-23

A high performance capacitor is described which is fabricated from nano-structure multilayer materials, such as by controlled, reactive sputtering, and having very high energy-density, high specific energy and high voltage breakdown. The multilayer capacitors, for example, may be fabricated in a ``notepad`` configuration composed of 200--300 alternating layers of conductive and dielectric materials so as to have a thickness of 1 mm, width of 200 mm, and length of 300 mm, with terminals at each end of the layers suitable for brazing, thereby guaranteeing low contact resistance and high durability. The ``notepad`` capacitors may be stacked in single or multiple rows (series-parallel banks) to increase the voltage and energy density. 5 figs.

Application of VSC-HVDC with Shunt Connected SMES for Compensation of Power Fluctuation

NASA Astrophysics Data System (ADS)

Linn, Zarchi; Kakigano, Hiroaki; Miura, Yushi; Ise, Toshifumi

This paper describes the application of VSC-HVDC (High Voltage DC Transmission using Voltage Source Converter) with shunt connected SMES (Superconducting Magnetic Energy Storage) for compensation of power fluctuation caused by fluctuating power source such as photovoltaics and wind turbines. The objectives of this proposed system is to smooth out fluctuating power in one terminal side of HVDC in order to avoid causing power system instability and frequency deviation by absorbing or providing power according to the system requirement while another terminal side power is fluctuated. The shunt connected SMES charges and discharges the energy to and from the dc side and it compensates required power of fluctuation to obtain constant power flow in one terminal side of VSC-HVDC system. This system configuration has ability for power system stabilization in the case of power fluctuation from natural energy source. PSCAD/EMTDC simulation is used to evaluate the performance of applied system configuration and control method.

Remote Monitor Alarm System

NASA Technical Reports Server (NTRS)

Stute, Robert A. (Inventor); Galloway, F. Houston (Inventor); Medelius, Pedro J. (Inventor); Swindle, Robert W. (Inventor); Bierman, Tracy A. (Inventor)

1996-01-01

A remote monitor alarm system monitors discrete alarm and analog power supply voltage conditions at remotely located communications terminal equipment. A central monitoring unit (CMU) is connected via serial data links to each of a plurality of remote terminal units (RTUS) that monitor the alarm and power supply conditions of the remote terminal equipment. Each RTU can monitor and store condition information of both discrete alarm points and analog power supply voltage points in its associated communications terminal equipment. The stored alarm information is periodically transmitted to the CMU in response to sequential polling of the RTUS. The number of monitored alarm inputs and permissible voltage ranges for the analog inputs can be remotely configured at the CMU and downloaded into programmable memory at each RTU. The CMU includes a video display, a hard disk memory, a line printer and an audio alarm for communicating and storing the alarm information received from each RTU.

MHD generator with improved network coupling electrodes to a load

DOEpatents

Rosa, Richard J.

1977-01-01

An MHD generator has a plurality of segmented electrodes extending longitudinally of a duct, whereby progressively increasing high DC voltages are derived from a set of cathode electrodes and progressively increasing low DC voltages are derived from a set of anode electrodes. First and second load terminals are respectively connected to the cathode and anode electrodes by separate coupling networks, each of which includes a number of SCR's and a number of diode rectifiers.

Combinatorial approach toward high-throughput analysis of direct methanol fuel cells.

PubMed

Jiang, Rongzhong; Rong, Charles; Chu, Deryn

2005-01-01

A 40-member array of direct methanol fuel cells (with stationary fuel and convective air supplies) was generated by electrically connecting the fuel cells in series. High-throughput analysis of these fuel cells was realized by fast screening of voltages between the two terminals of a fuel cell at constant current discharge. A large number of voltage-current curves (200) were obtained by screening the voltages through multiple small-current steps. Gaussian distribution was used to statistically analyze the large number of experimental data. The standard deviation (sigma) of voltages of these fuel cells increased linearly with discharge current. The voltage-current curves at various fuel concentrations were simulated with an empirical equation of voltage versus current and a linear equation of sigma versus current. The simulated voltage-current curves fitted the experimental data well. With increasing methanol concentration from 0.5 to 4.0 M, the Tafel slope of the voltage-current curves (at sigma=0.0), changed from 28 to 91 mV.dec-1, the cell resistance from 2.91 to 0.18 Omega, and the power output from 3 to 18 mW.cm-2.

Adjustable electronic load-alarm relay

DOEpatents

Mason, Charles H.; Sitton, Roy S.

1976-01-01

This invention is an improved electronic alarm relay for monitoring the current drawn by an AC motor or other electrical load. The circuit is designed to measure the load with high accuracy and to have excellent alarm repeatability. Chattering and arcing of the relay contacts are minimal. The operator can adjust the set point easily and can re-set both the high and the low alarm points by means of one simple adjustment. The relay includes means for generating a signal voltage proportional to the motor current. In a preferred form of the invention a first operational amplifier is provided to generate a first constant reference voltage which is higher than a preselected value of the signal voltage. A second operational amplifier is provided to generate a second constant reference voltage which is lower than the aforementioned preselected value of the signal voltage. A circuit comprising a first resistor serially connected to a second resistor is connected across the outputs of the first and second amplifiers, and the junction of the two resistors is connected to the inverting terminal of the second amplifier. Means are provided to compare the aforementioned signal voltage with both the first and second reference voltages and to actuate an alarm if the signal voltage is higher than the first reference voltage or lower than the second reference voltage.

Calcium-induced calcium release in rod photoreceptor terminals boosts synaptic transmission during maintained depolarization

PubMed Central

Cadetti, Lucia; Bryson, Eric J.; Ciccone, Cory A.; Rabl, Katalin; Thoreson, Wallace B.

2008-01-01

We examined the contribution of calcium-induced calcium release (CICR) to synaptic transmission from rod photoreceptor terminals. Whole-cell recording and confocal calcium imaging experiments were conducted on rods with intact synaptic terminals in a retinal slice preparation from salamander. Low concentrations of ryanodine stimulated calcium increases in rod terminals, consistent with the presence of ryanodine receptors. Application of strong depolarizing steps (−70 to −10 mV) exceeding 200 ms or longer in duration evoked a wave of calcium that spread across the synaptic terminals of voltage-clamped rods. This secondary calcium increase was blocked by high concentrations of ryanodine, indicating it was due to CICR. Ryanodine (50 μM) had no significant effect on rod calcium current (Ica) although it slightly diminished rod light-evoked voltage responses. Bath application of 50 μM ryanodine strongly inhibited light-evoked currents in horizontal cells. Whether applied extracellularly or delivered into the rod cell through the patch pipette, ryanodine (50 μM) also inhibited excitatory post-synaptic currents (EPSCs) evoked in horizontal cells by depolarizing steps applied to rods. Ryanodine caused a preferential reduction in the later portions of EPSCs evoked by depolarizing steps of 200 ms or longer. These results indicate that CICR enhances calcium increases in rod terminals evoked by sustained depolarization, which in turn acts to boost synaptic exocytosis from rods. PMID:16819987

High-performance fractional order terminal sliding mode control strategy for DC-DC Buck converter

PubMed Central

Xu, Dan; Zhou, Huan; Bai, Anning; Lu, Wei

2017-01-01

This paper presents an adaption of the fractional order terminal sliding mode control (AFTSMC) strategy for DC-DC Buck converter. The following strategy aims to design a novel nonlinear sliding surface function, with a double closed-loop structure of voltage and current. This strategy is a fusion of two characteristics: terminal sliding mode control (TSMC) and fractional order calculation (FOC). In addition, the influence of “the controller parameters” on the “performance of double closed-loop system” is investigated. It is observed that the value of terminal power has to be chosen to make a compromise between start-up and transient response of the converter. Therefore the AFTSMC strategy chooses the value of the terminal power adaptively, and this strategy can lead to the appropriate number of fractional order as well. Furthermore, through the fractional order analysis, the system can reach the sliding mode surface in a finite time. And the theoretical considerations are verified by numerical simulation. The performance of the AFTSMC and TSMC strategies is tested by computer simulations. And the comparison simulation results show that the AFTSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes. Moreover, AFTSMC obtains a faster dynamical response, smaller steady-state error rate and lower overshoot. PMID:29084255

High-performance fractional order terminal sliding mode control strategy for DC-DC Buck converter.

PubMed

Wang, Jianlin; Xu, Dan; Zhou, Huan; Bai, Anning; Lu, Wei

2017-01-01

This paper presents an adaption of the fractional order terminal sliding mode control (AFTSMC) strategy for DC-DC Buck converter. The following strategy aims to design a novel nonlinear sliding surface function, with a double closed-loop structure of voltage and current. This strategy is a fusion of two characteristics: terminal sliding mode control (TSMC) and fractional order calculation (FOC). In addition, the influence of "the controller parameters" on the "performance of double closed-loop system" is investigated. It is observed that the value of terminal power has to be chosen to make a compromise between start-up and transient response of the converter. Therefore the AFTSMC strategy chooses the value of the terminal power adaptively, and this strategy can lead to the appropriate number of fractional order as well. Furthermore, through the fractional order analysis, the system can reach the sliding mode surface in a finite time. And the theoretical considerations are verified by numerical simulation. The performance of the AFTSMC and TSMC strategies is tested by computer simulations. And the comparison simulation results show that the AFTSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes. Moreover, AFTSMC obtains a faster dynamical response, smaller steady-state error rate and lower overshoot.

Observation of oscillatory relaxation in the Sn-terminated surface of epitaxial rock-salt SnSe { 111 } topological crystalline insulator

NASA Astrophysics Data System (ADS)

Jin, Wencan; Dadap, Jerry; Osgood, Richard; Vishwanath, Suresh; Lien, Huai-Hsun; Chaney, Alexander; Xing, Huili; Liu, Jianpeng; Kong, Lingyuan; Ma, Junzhang; Qian, Tian; Ding, Hong; Sadowski, Jerzy; Dai, Zhongwei; Pohl, Karsten; Lou, Rui; Wang, Shancai; Liu, Xinyu; Furdyna, Jacek

Topological crystalline insulators have been recently observed in rock-salt SnSe { 111 } thin films. Previous studies have suggested that the Se-terminated surface of this thin film with hydrogen passivation is a preferred configuration. In this work, synchrotron-based angle-resolved photoemission spectroscopy, along with density functional theory calculations, are used to demonstrate conclusively that a rock-salt SnSe { 111 } thin film has a stable Sn-terminated surface. These observations are supported by low energy electron diffraction (LEED) intensity-voltage measurements and dynamical LEED calculations, which further show that the Sn-terminated SnSe { 111 } thin film has undergone an oscillatory surface structural relaxation. In sharp contrast to the Se-terminated counterpart, the Dirac surface state in the Sn-terminated SnSe { 111 } thin film yields a high Fermi velocity, 0 . 50 ×106 m/s, which may lead to high-speed electronic device applications. DOE No. DE-FG 02-04-ER-46157.

Carbon nanotube vacuum gauges with wide-dynamic range and processes thereof

NASA Technical Reports Server (NTRS)

Manohara, Harish (Inventor); Kaul, Anupama B. (Inventor)

2013-01-01

A miniature thermal conductivity gauge employs a carbon single-walled-nanotube. The gauge operates on the principle of thermal exchange between the voltage-biased nanotube and the surrounding gas at low levels of power and low temperatures to measure vacuum across a wide dynamic range. The gauge includes two terminals, a source of constant voltage to the terminals, a single-walled carbon nanotube between the terminals, a calibration of measured conductance of the nanotube to magnitudes of surrounding vacuum and a current meter in electrical communication with the source of constant voltage. Employment of the nanotube for measuring vacuum includes calibrating the electrical conductance of the nanotube to magnitudes of vacuum, exposing the nanotube to a vacuum, applying a constant voltage across the nanotube, measuring the electrical conductance of the nanotube in the vacuum with the constant voltage applied and converting the measured electrical conductance to the corresponding calibrated magnitude of vacuum using the calibration. The nanotube may be suspended to minimize heat dissipation through the substrate, increasing sensitivity at even tower pressures.

Voltage Scaling of Graphene Device on SrTiO3 Epitaxial Thin Film.

PubMed

Park, Jeongmin; Kang, Haeyong; Kang, Kyeong Tae; Yun, Yoojoo; Lee, Young Hee; Choi, Woo Seok; Suh, Dongseok

2016-03-09

Electrical transport in monolayer graphene on SrTiO3 (STO) thin film is examined in order to promote gate-voltage scaling using a high-k dielectric material. The atomically flat surface of thin STO layer epitaxially grown on Nb-doped STO single-crystal substrate offers good adhesion between the high-k film and graphene, resulting in nonhysteretic conductance as a function of gate voltage at all temperatures down to 2 K. The two-terminal conductance quantization under magnetic fields corresponding to quantum Hall states survives up to 200 K at a magnetic field of 14 T. In addition, the substantial shift of charge neutrality point in graphene seems to correlate with the temperature-dependent dielectric constant of the STO thin film, and its effective dielectric properties could be deduced from the universality of quantum phenomena in graphene. Our experimental data prove that the operating voltage reduction can be successfully realized due to the underlying high-k STO thin film, without any noticeable degradation of graphene device performance.

Correlation between the thermal performance and the microstructure of the material used in medium and high voltage transformer terminals

NASA Astrophysics Data System (ADS)

Salas, Y. J.; Vera-Monroy, S. P.; Mejia-Camacho, A.; Rivera, W.

2017-12-01

In Colombia, energy companies neglect the distribution that represents the main and most valuable process, presenting shortcomings in prevention and forecasting programs, using contractors who perform corrective maintenance of the components without guaranteeing the quality and performance of the materials. Within the process, the terminals determine the effective connection between the voltage line and the transformer, which have faults that are evidenced by the thermal deterioration of the material. In this work, a diagnosis of the thermal performance of these components was carried out and it was correlated with the microstructure, observing variations of the working temperature, with a thermography camera, for three types of terminals, which were classified by X-ray fluorescence in brass Z20, Z40 and Z60, and for two types of connection, copper and aluminium. The microstructure results showed that copper is the conductor that degrades the terminals faster, evidencing cracking of the material; on the other hand, the Z40 brass was the most stable with the lowest temperature variation regardless of the conductor diameter; however, in all cases the behaviour of higher temperature to lower calibre is satisfied.

SEMICONDUCTOR INTEGRATED CIRCUITS: A quasi-3-dimensional simulation method for a high-voltage level-shifting circuit structure

NASA Astrophysics Data System (ADS)

Jizhi, Liu; Xingbi, Chen

2009-12-01

A new quasi-three-dimensional (quasi-3D) numeric simulation method for a high-voltage level-shifting circuit structure is proposed. The performances of the 3D structure are analyzed by combining some 2D device structures; the 2D devices are in two planes perpendicular to each other and to the surface of the semiconductor. In comparison with Davinci, the full 3D device simulation tool, the quasi-3D simulation method can give results for the potential and current distribution of the 3D high-voltage level-shifting circuit structure with appropriate accuracy and the total CPU time for simulation is significantly reduced. The quasi-3D simulation technique can be used in many cases with advantages such as saving computing time, making no demands on the high-end computer terminals, and being easy to operate.

Correlations between the interfacial chemistry and current-voltage behavior of n-GaAs/liquid junctions

NASA Technical Reports Server (NTRS)

Tufts, Bruce J.; Casagrande, Louis G.; Lewis, Nathan S.; Grunthaner, Frank J.

1990-01-01

Correlations between the surface chemistry of etched, (100) oriented n-GaAs electrodes and their subsequent photoelectrochemical behavior have been probed by high-resolution X-ray photoelectron spectroscopy. GaAs photoanodes were chemically treated to prepare either an oxide-free near stoichiometric surface, a surface enriched in zero-valent arsenic or a substrate-oxide terminated surface. The current-voltage (I-V) behavior of each surface type was subsequently monitored in contact with several electrolytes.

Effects of ramp reset pulses on the address discharge in a shadow mask plasma display panel

NASA Astrophysics Data System (ADS)

Yang, Lanlan; Tu, Yan; Zhang, Xiong; Jiang, Youyan; Zhang, Jian; Wang, Baoping

2007-05-01

A two-dimensional self-consistent numerical simulation model is used to analyse the effects of the ramp reset pulses on the address discharge in a shadow mask plasma display panel (SM-PDP). Some basic parameters such as the slope of the ramp pulse and the terminal voltage of the ramp reset period are varied to investigate their effects. The simulation results illustrate that the wall voltage is mainly decided by the terminal voltage and the firing voltage at the end of the ramp reset period. Moreover, the variation of the ramp slope will also bring a few modifications to the wall voltage. The priming particles in the beginning of the addressing period are related to the slope of the ramping down voltage pulse. The simulation results can help us optimize the driving scheme of the SM-PDP.

Cross-differential amplifier

NASA Technical Reports Server (NTRS)

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2010-01-01

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Cross-differential amplifier

NASA Technical Reports Server (NTRS)

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2011-01-01

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Cross-differential amplifier

NASA Technical Reports Server (NTRS)

Aoki, Ichiro (Inventor); Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor)

2013-01-01

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Cross-differential amplifier

NASA Technical Reports Server (NTRS)

Hajimiri, Seyed-Ali (Inventor); Kee, Scott D. (Inventor); Aoki, Ichiro (Inventor)

2008-01-01

A cross-differential amplifier is provided. The cross-differential amplifier includes an inductor connected to a direct current power source at a first terminal. A first and second switch, such as transistors, are connected to the inductor at a second terminal. A first and second amplifier are connected at their supply terminals to the first and second switch. The first and second switches are operated to commutate the inductor between the amplifiers so as to provide an amplified signal while limiting the ripple voltage on the inductor and thus limiting the maximum voltage imposed across the amplifiers and switches.

Optimal Dynamic Sub-Threshold Technique for Extreme Low Power Consumption for VLSI

NASA Technical Reports Server (NTRS)

Duong, Tuan A.

2012-01-01

For miniaturization of electronics systems, power consumption plays a key role in the realm of constraints. Considering the very large scale integration (VLSI) design aspect, as transistor feature size is decreased to 50 nm and below, there is sizable increase in the number of transistors as more functional building blocks are embedded in the same chip. However, the consequent increase in power consumption (dynamic and leakage) will serve as a key constraint to inhibit the advantages of transistor feature size reduction. Power consumption can be reduced by minimizing the voltage supply (for dynamic power consumption) and/or increasing threshold voltage (V(sub th), for reducing leakage power). When the feature size of the transistor is reduced, supply voltage (V(sub dd)) and threshold voltage (V(sub th)) are also reduced accordingly; then, the leakage current becomes a bigger factor of the total power consumption. To maintain low power consumption, operation of electronics at sub-threshold levels can be a potentially strong contender; however, there are two obstacles to be faced: more leakage current per transistor will cause more leakage power consumption, and slow response time when the transistor is operated in weak inversion region. To enable low power consumption and yet obtain high performance, the CMOS (complementary metal oxide semiconductor) transistor as a basic element is viewed and controlled as a four-terminal device: source, drain, gate, and body, as differentiated from the traditional approach with three terminals: i.e., source and body, drain, and gate. This technique features multiple voltage sources to supply the dynamic control, and uses dynamic control to enable low-threshold voltage when the channel (N or P) is active, for speed response enhancement and high threshold voltage, and when the transistor channel (N or P) is inactive, to reduce the leakage current for low-leakage power consumption.

Inflation Fighters.

ERIC Educational Resources Information Center

Cohen, Sheldon H., Ed.

1983-01-01

Describes a low-cost, high-voltage, two-terminal, constant-current source for student use in electrophoresis experiments (includes circuit diagram) and a simple device for the continuous registering of gas flows. Also lists seven cost-saving tips for chemical reagent, including use decorative stones (purchased from nursery stores) in place of…

Industrialization of the ion plating process

NASA Technical Reports Server (NTRS)

Spalvins, T.

1976-01-01

A new process referred to as ion plating by induction heating (IPIH) is described, which combines the advantages of both ion plating and induction heating. The IPIH apparatus consists of the specimen (cathode) to be coated and the evaporation heating source, which is a ceramic crucible containing the metal to be heated. The specimen is an internal part of the high-voltage ceramic-metal vacuum feedthrough and is connected to the negative terminal of the high-voltage power supply, the positive terminal of the power supply being grounded. The plating conditions are the same as those most commonly used in industrial ion plating. A number of metals - such as nickel, iron, platinum - which were practically impossible to deposit by resistance heating evaporation can now be effectively evaporated and deposited to any desired thickness. Excellent adherence is observed for many metals deposited on various metal surfaces in thicknesses from 0.15 to 50 microns, regardless of the materials selected for coating and substrate.

Technical Challenges and Potential Solutions for Cross-Country Multi-Terminal Superconducting DC Power Cables

NASA Astrophysics Data System (ADS)

Al-Taie, A.; Graber, L.; Pamidi, S. V.

2017-12-01

Opportunities for applications of high temperature superconducting (HTS) DC power cables for long distance power transmission in increasing the reliability of the electric power grid and to enable easier integration of distributed renewable sources into the grid are discussed. The gaps in the technology developments both in the superconducting cable designs and cryogenic systems as well as power electronic devices are identified. Various technology components in multi-terminal high voltage DC power transmission networks and the available options are discussed. The potential of ongoing efforts in the development of superconducting DC transmission systems is discussed.

Method of making high breakdown voltage semiconductor device

DOEpatents

Arthur, Stephen D.; Temple, Victor A. K.

1990-01-01

A semiconductor device having at least one P-N junction and a multiple-zone junction termination extension (JTE) region which uniformly merges with the reverse blocking junction is disclosed. The blocking junction is graded into multiple zones of lower concentration dopant adjacent termination to facilitate merging of the JTE to the blocking junction and placing of the JTE at or near the high field point of the blocking junction. Preferably, the JTE region substantially overlaps the graded blocking junction region. A novel device fabrication method is also provided which eliminates the prior art step of separately diffusing the JTE region.

1/f noise in metallic and semiconducting carbon nanotubes

NASA Astrophysics Data System (ADS)

Reza, Shahed; Huynh, Quyen T.; Bosman, Gijs; Sippel-Oakley, Jennifer; Rinzler, Andrew G.

2006-11-01

The charge transport and noise properties of three terminal, gated devices containing multiple single-wall metallic and semiconducting carbon nanotubes were measured at room temperature. Applying a high voltage pulsed bias at the drain terminal the metallic tubes were ablated sequentially, enabling the separation of measured conductance and 1/f noise into metallic and semiconducting nanotube contributions. The relative low frequency excess noise of the metallic tubes was observed to be two orders of magnitude lower than that of the semiconductor tubes.

High breakdown voltage quasi-two-dimensional β-Ga2O3 field-effect transistors with a boron nitride field plate

NASA Astrophysics Data System (ADS)

Bae, Jinho; Kim, Hyoung Woo; Kang, In Ho; Yang, Gwangseok; Kim, Jihyun

2018-03-01

We have demonstrated a β-Ga2O3 metal-semiconductor field-effect transistor (MESFET) with a high off-state breakdown voltage (344 V), based on a quasi-two-dimensional β-Ga2O3 field-plated with hexagonal boron nitride (h-BN). Both the β-Ga2O3 and h-BN were mechanically exfoliated from their respective crystal substrates, followed by dry-transfer onto a SiO2/Si substrate for integration into a high breakdown voltage quasi-two-dimensional β-Ga2O3 MESFETs. N-type conducting behavior was observed in the fabricated β-Ga2O3 MESFETs, along with a high on/off current ratio (>106) and excellent current saturation. A three-terminal off-state breakdown voltage of 344 V was obtained, with a threshold voltage of -7.3 V and a subthreshold swing of 84.6 mV/dec. The distribution of electric fields in the quasi-two-dimensional β-Ga2O3 MESFETs was simulated to analyze the role of the dielectric h-BN field plate in improving the off-state breakdown voltage. The stability of the field-plated β-Ga2O3 MESFET in air was confirmed after storing the MESFET in ambient air for one month. Our results pave the way for unlocking the full potential of β-Ga2O3 for use in a high-power nano-device with an ultrahigh breakdown voltage.

Gate-tunable memristive phenomena mediated by grain boundaries in single-layer MoS2

NASA Astrophysics Data System (ADS)

Sangwan, Vinod K.; Jariwala, Deep; Kim, In Soo; Chen, Kan-Sheng; Marks, Tobin J.; Lauhon, Lincoln J.; Hersam, Mark C.

2015-05-01

Continued progress in high-speed computing depends on breakthroughs in both materials synthesis and device architectures. The performance of logic and memory can be enhanced significantly by introducing a memristor, a two-terminal device with internal resistance that depends on the history of the external bias voltage. State-of-the-art memristors, based on metal-insulator-metal (MIM) structures with insulating oxides, such as TiO2, are limited by a lack of control over the filament formation and external control of the switching voltage. Here, we report a class of memristors based on grain boundaries (GBs) in single-layer MoS2 devices. Specifically, the resistance of GBs emerging from contacts can be easily and repeatedly modulated, with switching ratios up to ˜103 and a dynamic negative differential resistance (NDR). Furthermore, the atomically thin nature of MoS2 enables tuning of the set voltage by a third gate terminal in a field-effect geometry, which provides new functionality that is not observed in other known memristive devices.

Electro-optical phenomena based on ionic liquids in an optofluidic waveguide.

PubMed

He, Xiaodong; Shao, Qunfeng; Cao, Pengfei; Kong, Weijie; Sun, Jiqian; Zhang, Xiaoping; Deng, Youquan

2015-03-07

An optofluidic waveguide with a simple two-terminal electrode geometry, when filled with an ionic liquid (IL), forms a lateral electric double-layer capacitor under a direct current (DC) electric field, which allows the realization of an extremely high carrier density in the vicinity of the electrode surface and terminals to modulate optical transmission at room temperature under low voltage operation (0 to 4 V). The unique electro-optical phenomenon of ILs was investigated at three wavelengths (663, 1330 and 1530 nm) using two waveguide geometries. Strong electro-optical modulations with different efficiencies were observed at the two near-infrared (NIR) wavelengths, while no detectable modulation was observed at 663 nm. The first waveguide geometry was used to investigate the position-dependent modulation along the waveguide; the strongest modulation was observed in the vicinity of the electrode terminal. The modulation phase is associated with the applied voltage polarity, which increases in the vicinity of the negative electrode and decreases at the positive electrode. The second waveguide geometry was used to improve the modulation efficiency. Meanwhile, the electro-optical modulations of seven ILs were compared at an applied voltage ranging from ±2 V to ±3.5 V. The results reveal that the modulation amplitude and response speed increase with increasing applied voltage, as well as the electrical conductivity of ILs. Despite the fact that the response speed isn't fast due to the high ionic density of ILs, the modulation amplitude can reach up to 6.0 dB when a higher voltage (U = ±3.5 V) is applied for the IL [Emim][BF4]. Finally, the physical explanation of the phenomenon was discussed. The effect of the change in IL structure on the electro-optical phenomena was investigated in another new experiment. The results reveal that the electro-optical phenomenon is probably caused mainly by the change in carrier concentration (ion redistribution near charged electrodes), which induces the enhancement and suppression of NIR optical absorption (contributed by C-H and N-H groups) in the vicinity of the negative electrode and positive electrode, respectively.

Apparatus and Method for Generating Thrust Using a Two Dimensional, Asymmetrical Capacitor Module

NASA Technical Reports Server (NTRS)

Campbell, Jonathan W. (Inventor)

2001-01-01

A capacitor module system is provided for creating a thrust force. The system includes a capacitor module provided with a first conductive element having a cylindrical geometry. The first conductive element can be a hollow cylinder or a solid cylinder. The capacitor module also includes a second conductive element axially spaced from the first conductive element and of smaller axial extent. The second conductive element can be a flat disk, a dome, or a conductive tip at the end of a dielectric rod. A dielectric element is disposed between the first conductive element and the second conductive element. The system also includes a high voltage source having first and second terminals connected respectively to the first and second conductive elements. The high voltage source applies a high voltage to the conductive elements of sufficient value to create a thrust force on the module inducing movement thereof.

Photoconductivity of few-layered p-WSe2 phototransistors via multi-terminal measurements

NASA Astrophysics Data System (ADS)

Pradhan, Nihar R.; Garcia, Carlos; Holleman, Joshua; Rhodes, Daniel; Parker, Chason; Talapatra, Saikat; Terrones, Mauricio; Balicas, Luis; McGill, Stephen A.

2016-12-01

Recently, two-dimensional materials and in particular transition metal dichalcogenides (TMDs) have been extensively studied because of their strong light-matter interaction and the remarkable optoelectronic response of their field-effect transistors (FETs). Here, we report a photoconductivity study from FETs built from few-layers of p-WSe2 measured in a multi-terminal configuration under illumination by a 532 nm laser source. The photogenerated current was measured as a function of the incident optical power, of the drain-to-source bias and of the gate voltage. We observe a considerably larger photoconductivity when the phototransistors were measured via a four-terminal configuration when compared to a two-terminal one. For an incident laser power of 248 nW, we extract 18 A W-1 and ˜4000% for the two-terminal responsivity (R) and the concomitant external quantum efficiency (EQE) respectively, when a bias voltage V ds = 1 V and a gate voltage V bg = 10 V are applied to the sample. R and EQE are observed to increase by 370% to ˜85 A W-1 and ˜20 000% respectively, when using a four-terminal configuration. Thus, we conclude that previous reports have severely underestimated the optoelectronic response of transition metal dichalcogenides, which in fact reveals a remarkable potential for photosensing applications.

Unpinning of rotating spiral waves in cardiac tissues by circularly polarized electric fields

PubMed Central

Feng, Xia; Gao, Xiang; Pan, De-Bei; Li, Bing-Wei; Zhang, Hong

2014-01-01

Spiral waves anchored to obstacles in cardiac tissues may cause lethal arrhythmia. To unpin these anchored spirals, comparing to high-voltage side-effect traditional therapies, wave emission from heterogeneities (WEH) induced by the uniform electric field (UEF) has provided a low-voltage alternative. Here we provide a new approach using WEH induced by the circularly polarized electric field (CPEF), which has higher success rate and larger application scope than UEF, even with a lower voltage. And we also study the distribution of the membrane potential near an obstacle induced by CPEF to analyze its mechanism of unpinning. We hope this promising approach may provide a better alternative to terminate arrhythmia. PMID:24777360

OFCC based voltage and transadmittance mode instrumentation amplifier

NASA Astrophysics Data System (ADS)

Nand, Deva; Pandey, Neeta; Pandey, Rajeshwari; Tripathi, Prateek; Gola, Prashant

2017-07-01

The operational floating current conveyor (OFCC) is a versatile active block due to the availability of both low and high input and output impedance terminals. This paper addresses the realization of OFCC based voltage and transadmittance mode instrumentation amplifiers (VMIA and TAM IA). It employs three OFCCs and seven resistors. The transadmittance mode operation can easily be obtained by simply connecting an OFCC based voltage to current converter at the output. The effect of non-idealities of OFCC, in particular finite transimpedance and tracking error, on system performance is also dealt with and corresponding mathematical expressions are derived. The functional verification is performed through SPICE simulation using CMOS based implementation of OFCC.

Bivariate quadratic method in quantifying the differential capacitance and energy capacity of supercapacitors under high current operation

NASA Astrophysics Data System (ADS)

Goh, Chin-Teng; Cruden, Andrew

2014-11-01

Capacitance and resistance are the fundamental electrical parameters used to evaluate the electrical characteristics of a supercapacitor, namely the dynamic voltage response, energy capacity, state of charge and health condition. In the British Standards EN62391 and EN62576, the constant capacitance method can be further improved with a differential capacitance that more accurately describes the dynamic voltage response of supercapacitors. This paper presents a novel bivariate quadratic based method to model the dynamic voltage response of supercapacitors under high current charge-discharge cycling, and to enable the derivation of the differential capacitance and energy capacity directly from terminal measurements, i.e. voltage and current, rather than from multiple pulsed-current or excitation signal tests across different bias levels. The estimation results the author achieves are in close agreement with experimental measurements, within a relative error of 0.2%, at various high current levels (25-200 A), more accurate than the constant capacitance method (4-7%). The archival value of this paper is the introduction of an improved quantification method for the electrical characteristics of supercapacitors, and the disclosure of the distinct properties of supercapacitors: the nonlinear capacitance-voltage characteristic, capacitance variation between charging and discharging, and distribution of energy capacity across the operating voltage window.

Investigation of defect-induced abnormal body current in fin field-effect-transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Kuan-Ju; Tsai, Jyun-Yu; Lu, Ying-Hsin

2015-08-24

This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal.

An ion beam facility based on a 3 MV tandetron accelerator in Sichuan University, China

NASA Astrophysics Data System (ADS)

Han, Jifeng; An, Zhu; Zheng, Gaoqun; Bai, Fan; Li, Zhihui; Wang, Peng; Liao, Xiaodong; Liu, Mantian; Chen, Shunli; Song, Mingjiang; Zhang, Jun

2018-03-01

A new ion beam facility based on a 3 MV tandetron accelerator system has been installed in Sichuan University, China. The facility was developed by High Voltage Engineering Europa and consists of three high-energy beam lines including the ion beam analysis, ion implantation and nuclear physics experiment end stations, respectively. The terminal voltage stability of the accelerator is better than ±30 V, and the brightness of the proton beam is approximately 5.06 A/rad2/m2/eV. The system demonstrates a great application potential in fields such as nuclear, material and environmental studies.

Automatic control and detector for three-terminal resistance measurement

DOEpatents

Fasching, George E.

1976-10-26

A device is provided for automatic control and detection in a three-terminal resistance measuring instrument. The invention is useful for the rapid measurement of the resistivity of various bulk material with a three-terminal electrode system. The device maintains the current through the sample at a fixed level while measuring the voltage across the sample to detect the sample resistance. The three-electrode system contacts the bulk material and the current through the sample is held constant by means of a control circuit connected to a first of the three electrodes and works in conjunction with a feedback controlled amplifier to null the voltage between the first electrode and a second electrode connected to the controlled amplifier output. An A.C. oscillator provides a source of sinusoidal reference voltage of the frequency at which the measurement is to be executed. Synchronous reference pulses for synchronous detectors in the control circuit and an output detector circuit are provided by a synchronous pulse generator. The output of the controlled amplifier circuit is sampled by an output detector circuit to develop at an output terminal thereof a D.C. voltage which is proportional to the sample resistance R. The sample resistance is that segment of the sample between the area of the first electrode and the third electrode, which is connected to ground potential.

Preliminary Development and Testing of a Self-Injecting Gallium MPD Thruster

NASA Technical Reports Server (NTRS)

Thomas, Robert E.; Burton, Rodney L.; Polzin, Kurt A.

2008-01-01

Discharge current and terminal voltage measurements were performed on a gallium electromagnetic thruster at discharge currents in the range of 20-54 kA. It was found that the arc impedance has a value of 6-7 m(Omega) at peak current. The absence of high-frequency oscillations in the terminal voltage trace indicates lack of the "onset" condition often seen in MPD arcs, suggesting that a sufficient number of charge carriers are present for current conduction. The mass ablated per pulse was not measured experimentally; however the mass flow rate was calculated using an ion current assumption and an anode power balance. Measurement of arc impedance predicts a temperature of 3.5 eV which from Saha equilibrium corresponds to Z = 2.0 - 3.5, and assuming Z = 2 yields an Isp of 3000 s and thrust efficiency of 50%.

Intelligent energy harvesting scheme for microbial fuel cells: Maximum power point tracking and voltage overshoot avoidance

NASA Astrophysics Data System (ADS)

Alaraj, Muhannad; Radenkovic, Miloje; Park, Jae-Do

2017-02-01

Microbial fuel cells (MFCs) are renewable and sustainable energy sources that can be used for various applications. The MFC output power depends on its biochemical conditions as well as the terminal operating points in terms of output voltage and current. There exists one operating point that gives the maximum possible power from the MFC, maximum power point (MPP), for a given operating condition. However, this MPP may vary and needs to be tracked in order to maintain the maximum power extraction from the MFC. Furthermore, MFC reactors often develop voltage overshoots that cause drastic drops in the terminal voltage, current, and the output power. When the voltage overshoot happens, an additional control measure is necessary as conventional MPPT algorithms will fail because of the change in the voltage-current relationship. In this paper, the extremum seeking (ES) algorithm was used to track the varying MPP and a voltage overshoot avoidance (VOA) algorithm is developed to manage the voltage overshoot conditions. The proposed ES-MPPT with VOA algorithm was able to extract 197.2 mJ during 10-min operation avoiding voltage overshoot, while the ES MPPT-only scheme stopped harvesting after only 18.75 mJ because of the voltage overshoot happened at 0.4 min.

A Fault Location Algorithm for Two-End Series-Compensated Double-Circuit Transmission Lines Using the Distributed Parameter Line Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kang, Ning; Gombos, Gergely; Mousavi, Mirrasoul J.

A new fault location algorithm for two-end series-compensated double-circuit transmission lines utilizing unsynchronized two-terminal current phasors and local voltage phasors is presented in this paper. The distributed parameter line model is adopted to take into account the shunt capacitance of the lines. The mutual coupling between the parallel lines in the zero-sequence network is also considered. The boundary conditions under different fault types are used to derive the fault location formulation. The developed algorithm directly uses the local voltage phasors on the line side of series compensation (SC) and metal oxide varistor (MOV). However, when potential transformers are not installedmore » on the line side of SC and MOVs for the local terminal, these measurements can be calculated from the local terminal bus voltage and currents by estimating the voltages across the SC and MOVs. MATLAB SimPowerSystems is used to generate cases under diverse fault conditions to evaluating accuracy. The simulation results show that the proposed algorithm is qualified for practical implementation.« less

A multi-GHz chaotic optoelectronic oscillator based on laser terminal voltage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, C. Y., E-mail: cychang@gatech.edu; UMI 2958 Georgia Tech-CNRS, Georgia Tech Lorraine, 2 Rue Marconi, F-57070 Metz; Choi, Daeyoung

2016-05-09

A multi-GHz chaotic optoelectronic oscillator based on an external cavity semiconductor laser (ECL) is demonstrated. Unlike the standard optoelectronic oscillators for microwave applications, we do not employ the dynamic light output incident on a photodiode to generate the microwave signal, but instead generate the microwave signal directly by measuring the terminal voltage V(t) of the laser diode of the ECL under constant-current operation, thus obviating the photodiode entirely.

Presynaptic excitability.

PubMed

Jackson, M B

1995-01-01

Based on functional characterizations with electrophysiological techniques, the channels in nerve terminals appear to be as diverse as channels in nerve cell bodies (Table I). While most presynaptic Ca2+ channels superficially resemble either N-type or L-type channels, variations in detail have necessitated the use of subscripts and other notations to indicate a nerve terminal-specific subtype (e.g., Wang et al., 1993). Variations such as these pose a serious obstacle to the identification of presynaptic channels based solely on the effects of channel blockers on synaptic transmission. Pharmacological sensitivity alone is not likely to help in determining functional properties. Crucial details, such as voltage sensitivity and inactivation, require direct examination. It goes without saying that every nerve terminal membrane contains Ca2+ channels as an entry pathway so that Ca2+ can trigger secretion. However, there appears to be no general specification of channel type, other than the exclusion of T-type Ca2+ channels. T-type Ca2+ channels are defined functionally by strong inactivation and low threshold. Some presynaptic Ca2+ channels inactivate (posterior pituitary and Xenopus nerve terminals), and others have a somewhat reduced voltage threshold (retinal bipolar neurons and squid giant synapse). Perhaps it is just a matter of time before a nerve terminal Ca2+ channel is found with both of these properties. The high threshold and strong inactivation of T-type Ca2+ channels are thought to be adaptations for oscillations and the regulation of bursting activity in nerve cell bodies. The nerve terminals thus far examined have no endogenous electrical activity, but rather are driven by the cell body. On functional grounds, it is then reasonable to anticipate finding T-type Ca2+ channels in nerve terminals that can generate electrical activity on their own. The rarity of such behavior in nerve terminals may be associated with the rarity of presynaptic T-type Ca2+ channels. In four of the five preparations reviewed in this chapter--motor nerve, squid giant synapse, ciliary ganglion, and retina bipolar neurons--evidence was presented that supports a location for Ca2+ channels that is very close to active zones of secretion. All of these synapses secrete from clear vesicles, and the speed and specificity of transduction provided by proximity may be a common feature of these rapid synapses. In contrast, the posterior pituitary secretion apparatus may be triggered by higher-affinity Ca2+ receptors and lower concentrations of Ca2+ (Lindau et al., 1992). This would correspond with the slower performance of peptidergic secretion, but because of the large stimuli needed to evoke release from neurosecretosomes, the possibility remains that the threshold for secretion is higher than that reported. While the role of Ca2+ as a trigger of secretion dictates a requirement for voltage-activated Ca2+ channels as universal components of the presynaptic membrane, the presence of other channels is more difficult to predict. Depolarizations caused by voltage-activated Na+ channels activate the presynaptic Ca2+ channels, but whether this depolarization requires Na+ channels in the presynaptic membrane itself may depend on the electrotonic length of the nerve terminal. Variations in density between motor nerve terminals may reflect species differences in geometry. The high Na+ channel density in the posterior pituitary reflects the great electrotonic length of this terminal arbor. Whether Na+ channels are abundant or not in a presynaptic membrane, K+ channels provide the most robust mechanism for limiting depolarization-induced Ca2+ entry. K+ channel blockers enhance transmission at most synapses. In general, K+ channels are abundant in nerve terminals, although their apparent lower priority compared to Ca2+ channels in the eyes of many investigators leaves us with fewer detailed investigations in some preparations. Most nerve terminals have more than

Low-voltage operation of Si-based ferroelectric field effect transistors using organic ferroelectrics, poly(vinylidene fluoride-trifluoroethylene), as a gate dielectric

NASA Astrophysics Data System (ADS)

Miyata, Yusuke; Yoshimura, Takeshi; Ashida, Atsushi; Fujimura, Norifumi

2016-04-01

Si-based metal-ferroelectric-semiconductor (MFS) capacitors have been fabricated using poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] as a ferroelectric gate. The pinhole-free P(VDF-TrFE) thin films with high resistivity were able to be prepared by spin-coating directly onto hydrogen-terminated Si. The capacitance-voltage (C-V) characteristics of the ferroelectric gate field effect transistor (FeFET) using this MFS structure clearly show butterfly-shaped hysteresis originating from the ferroelectricity, indicating carrier modulation on the Si surface at gate voltages below 2 V. The drain current-gate voltage (I D-V G) characteristics also show counterclockwise hysteresis at gate voltages below 5 V. This is the first report on the low-voltage operation of a Si-based FeFET using P(VDF-TrFE) as a gate dielectric. This organic gate FeFET without any insulator layer at the ferroelectric/Si interface should be one of the promising devices for overcoming the critical issues of the FeFET, such as depolarization field and a decrease in the gate voltage.

Technologies for suppressing charge-traps in novel p-channel Field-MOSFET with thick gate oxide

NASA Astrophysics Data System (ADS)

Miyoshi, Tomoyuki; Oshima, Takayuki; Noguchi, Junji

2015-05-01

High voltage laterally diffused MOS (LDMOS) FETs are widely used in analog applications. A Field-MOSFET with a thick gate oxide is one of the best ways of achieving a simpler design and smaller circuit footprint for high-voltage analog circuits. This paper focuses on an approach to improving the reliability of p-channel Field-MOSFETs. By introducing a fluorine implantation process and terminating fluorine at the LOCOS bird’s beak, the gate oxide breakdown voltage could be raised to 350 V at a high-slew rate and the negative bias temperature instability (NBTI) shift could be kept to within 15% over a product’s lifetime. By controlling the amount of charge in the insulating layer through improving the interlayer dielectric (ILD) deposition processes, a higher BVDSS of 370 V and 10-year tolerability of 300 V were obtained with an assisted reduced surface electric field (RESURF) effect. These techniques can supply an efficient solution for ensuring reliable high-performance applications.

Bi-directional power control system for voltage converter

DOEpatents

Garrigan, Neil Richard; King, Robert Dean; Schwartz, James Edward

1999-01-01

A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals.

Bi-directional power control system for voltage converter

DOEpatents

Garrigan, N.R.; King, R.D.; Schwartz, J.E.

1999-05-11

A control system for a voltage converter includes: a power comparator for comparing a power signal on input terminals of the converter with a commanded power signal and producing a power comparison signal; a power regulator for transforming the power comparison signal to a commanded current signal; a current comparator for comparing the commanded current signal with a measured current signal on output terminals of the converter and producing a current comparison signal; a current regulator for transforming the current comparison signal to a pulse width modulator (PWM) duty cycle command signal; and a PWM for using the PWM duty cycle command signal to control electrical switches of the converter. The control system may further include: a command multiplier for converting a voltage signal across the output terminals of the converter to a gain signal having a value between zero (0) and unity (1), and a power multiplier for multiplying the commanded power signal by the gain signal to provide a limited commanded power signal, wherein power comparator compares the limited commanded power signal with the power signal on the input terminals. 10 figs.

Using the intrinsic properties of silicon micro-ring modulators for characterization of RF termination

NASA Astrophysics Data System (ADS)

Wang, Zhao; Knights, Andrew P.

2017-02-01

We describe a direct experimental method to determine the effective driving voltage (Vpp) applied to a silicon photonic modulator possessing an impedance mismatch between the unterminated capacitive load and input source. This method thus permits subsequent estimation of the power consumption of an imperfectly terminated device as well as a deduction of load impedance for optimization of termination design. The capacitive load in this paper is a silicon micro-ring modulator with an integrated p-n junction acting as a phase shifter. The RF reflection under high-speed drive is directly determined from observation of the eye-diagram following measurement of the power transfer function for various junction bias.

Termination of atrial fibrillation using pulsed low-energy far-field stimulation

PubMed Central

Fenton, Flavio H.; Luther, Stefan; Cherry, Elizabeth M.; Otani, Niels F.; Krinsky, Valentin; Pumir, Alain; Bodenschatz, Eberhard; Gilmour, Robert F.

2010-01-01

Background Electrically-based therapies for terminating atrial fibrillation (AF) currently fall into two categories: anti-tachycardia pacing (ATP) and cardioversion. ATP utilizes low-intensity pacing stimuli delivered via a single electrode and is effective for terminating slower tachycardias, but is less effective for treating AF. In contrast, cardioversion uses a single high-voltage shock to terminate AF reliably, but the voltages required produce undesirable side effects, including tissue damage and pain. We propose a new method to terminate AF called far-field anti-fibrillation pacing (FF-AFP), which delivers a short train of low-intensity electrical pulses at the frequency of ATP, but from field electrodes. Prior theoretical work has suggested that this approach can create a large number of activation sites (“virtual” electrodes) that emit propagating waves within the tissue without implanting physical electrodes and thereby may be more effective than point-source stimulation. Methods and Results Using optical mapping in isolated perfused canine atrial preparations, we show that a series of pulses at low field strength (0.9-1.4 V/cm) is sufficient to entrain and subsequently extinguish AF with a success rate of 93 percent (69/74 trials in 8 preparations). We further demonstrate that the mechanism behind FFAFP success is the generation of wave emission sites within the tissue by the applied electric field, which entrains the tissue as the field is pulsed. Conclusions AF in our model can be terminated by FF-AFP using only 13% of the energy required for cardioversion. Further studies are needed to determine whether this marked reduction in energy can increase the effectiveness and safety of terminating atrial tachyarrhythmias clinically. PMID:19635972

Comparative study of high voltage bushing designs suitable for apparatus containing cryogenic helium gas

NASA Astrophysics Data System (ADS)

Rodrigo, H.; Graber, L.; Kwag, D. S.; Crook, D. G.; Trociewitz, B.

2013-10-01

The high voltage bushing forms a critical part of any termination on cables, transformers and other power system devices. Cryogenic entities such as superconducting cables or fault current limiters add more complexity to the design of the bushing. Even more complex are bushings designed for superconducting devices which are cooled by high pressure helium gas. When looking for a bushing suitable for dielectric cable tests in a helium gas cryostat no appropriate device could be found that fulfilled the criterion regarding partial discharge inception voltage level. Therefore we decided to design and manufacture a bushing in-house. In the present work we describe the dielectric tests and operational experience on three types of bushings: One was a modified commercially available ceramics feed through which we adopted for our special need. The second bushing was made of an epoxy resin, with an embedded copper squirrel cage arrangement at the flange, extending down about 30 cm into the cold end of the bushing. This feature reduced the electric field on the surface of the bushing to a negligible value. The third bushing was based on a hollow body consisting of glass fiber reinforced polymer and stainless steel filled with liquid nitrogen. The measurements showed that the dielectric quality of all three bushings exceeded the requirements for the intended purpose. The partial discharge (PD) data from these studies will be used for the design and fabrication of a cable termination for a specialized application on board a US Navy ship.

Quench simulation results for a 12-T twin-aperture dipole magnet

NASA Astrophysics Data System (ADS)

Cheng, Da; Salmi, Tiina; Xu, Qingjin; Peng, Quanling; Wang, Chengtao; Wang, Yingzhe; Kong, Ershuai; Zhang, Kai

2018-06-01

A 12-T twin-aperture subscale dipole magnet is being developed for SPPC pre-study at the Institute of High Energy Physics (IHEP). The magnet is comprised of 6 double-pancake coils which include 2 Nb3Sn coils and 4 NbTi coils. As the stored energy of the magnet is 0.452 MJ and the operation margin is only about 20% at 4.2 K, a quick and effective quench protection system is necessary during the test of this high field magnet. For the design of the quench protection system, attention was not only paid to the hotspot temperature and terminal voltage, but also the temperature gradient during the quench process due to the poor mechanical characteristics of the Nb3Sn cables. With the adiabatic analysis, numerical simulation and the finite element simulation, an optimized protection method is adopted, which contains a dump resistor and quench heaters. In this paper, the results of adiabatic analysis and quench simulation, such as current decay, hot-spot temperature and terminal voltage are presented in details.

Status of the University of Rochester tandem upgrade

NASA Astrophysics Data System (ADS)

Cross, Clinton; Miller, Thomas

1986-05-01

The status of the University of Rochester tandem Van de Graaff accelerator upgrade is reviewed. The accelerator upgrade to 18 MV consists of extended tubes, shielded resistors, dead-section ion pumping, two rotating insulating power shaft systems to provide power to the dead sections and terminal, and a pelletron charging system to replace the charging belt. Control of many of the accelerator operating systems will be done by two IBM personal computers. The negative ion injector diffusion pump, isolation transformer, preacceleration high-voltage power supply, and high-voltage corona enclosure will all be replaced. Finally, the SF6 gas handling system will be improved with the addition of a second set of gas dryers and a larger recirculating pump.

Modulation of voltage- and Ca2+-dependent gating of CaV1.3 L-type calcium channels by alternative splicing of a C-terminal regulatory domain.

PubMed

Singh, Anamika; Gebhart, Mathias; Fritsch, Reinhard; Sinnegger-Brauns, Martina J; Poggiani, Chiara; Hoda, Jean-Charles; Engel, Jutta; Romanin, Christoph; Striessnig, Jörg; Koschak, Alexandra

2008-07-25

Low voltage activation of Ca(V)1.3 L-type Ca(2+) channels controls excitability in sensory cells and central neurons as well as sinoatrial node pacemaking. Ca(V)1.3-mediated pacemaking determines neuronal vulnerability of dopaminergic striatal neurons affected in Parkinson disease. We have previously found that in Ca(V)1.4 L-type Ca(2+) channels, activation, voltage, and calcium-dependent inactivation are controlled by an intrinsic distal C-terminal modulator. Because alternative splicing in the Ca(V)1.3 alpha1 subunit C terminus gives rise to a long (Ca(V)1.3(42)) and a short form (Ca(V)1.3(42A)), we investigated if a C-terminal modulatory mechanism also controls Ca(V)1.3 gating. The biophysical properties of both splice variants were compared after heterologous expression together with beta3 and alpha2delta1 subunits in HEK-293 cells. Activation of calcium current through Ca(V)1.3(42A) channels was more pronounced at negative voltages, and inactivation was faster because of enhanced calcium-dependent inactivation. By investigating several Ca(V)1.3 channel truncations, we restricted the modulator activity to the last 116 amino acids of the C terminus. The resulting Ca(V)1.3(DeltaC116) channels showed gating properties similar to Ca(V)1.3(42A) that were reverted by co-expression of the corresponding C-terminal peptide C(116). Fluorescence resonance energy transfer experiments confirmed an intramolecular protein interaction in the C terminus of Ca(V)1.3 channels that also modulates calmodulin binding. These experiments revealed a novel mechanism of channel modulation enabling cells to tightly control Ca(V)1.3 channel activity by alternative splicing. The absence of the C-terminal modulator in short splice forms facilitates Ca(V)1.3 channel activation at lower voltages expected to favor Ca(V)1.3 activity at threshold voltages as required for modulation of neuronal firing behavior and sinoatrial node pacemaking.

Laboratory demonstration of lightning strike pattern on different roof tops installed with Franklin Rods

NASA Astrophysics Data System (ADS)

Ullah, Irshad; Baharom, MNR; Ahmed, H.; Luqman, HM.; Zainal, Zainab

2017-11-01

Protection against lightning is always a challenging job for the researcher. The consequences due to lightning on different building shapes needs a comprehensive knowledge in order to provide the information to the common man. This paper is mainly concern with lightning pattern when it strikes on the building with different shape. The work is based on the practical experimental work in high voltage laboratory. Different shapes of the scaled structures have been selected in order to investigate the equal distribution of lightning voltage. The equal distribution of lightning voltage will provide the maximum probability of lightning strike on air terminal of the selected shapes. Building shapes have a very important role in lightning protection. The shapes of the roof tops have different geometry and the Franklin rod installation is also varies with changing the shape of the roof top. According to the ambient weather condition of Malaysia high voltage impulse is applied on the lightning rod installed on different geometrical shape. The equal distribution of high voltage impulse is obtained as the geometry of the scaled structure is identical and the air gap for all the tested object is kept the same. This equal distribution of the lightning voltage also proves that the probability of lightning strike is on the corner and the edges of the building structure.

An analytic current-voltage model for quasi-ballistic III-nitride high electron mobility transistors

NASA Astrophysics Data System (ADS)

Li, Kexin; Rakheja, Shaloo

2018-05-01

We present an analytic model to describe the DC current-voltage (I-V) relationship in scaled III-nitride high electron mobility transistors (HEMTs) in which transport within the channel is quasi-ballistic in nature. Following Landauer's transport theory and charge calculation based on two-dimensional electrostatics that incorporates negative momenta states from the drain terminal, an analytic expression for current as a function of terminal voltages is developed. The model interprets the non-linearity of access regions in non-self-aligned HEMTs. Effects of Joule heating with temperature-dependent thermal conductivity are incorporated in the model in a self-consistent manner. With a total of 26 input parameters, the analytic model offers reduced empiricism compared to existing GaN HEMT models. To verify the model, experimental I-V data of InAlN/GaN with InGaN back-barrier HEMTs with channel lengths of 42 and 105 nm are considered. Additionally, the model is validated against numerical I-V data obtained from DC hydrodynamic simulations of an unintentionally doped AlGaN-on-GaN HEMT with 50-nm gate length. The model is also verified against pulsed I-V measurements of a 150-nm T-gate GaN HEMT. Excellent agreement between the model and experimental and numerical results for output current, transconductance, and output conductance is demonstrated over a broad range of bias and temperature conditions.

Digital automatic gain amplifier

NASA Technical Reports Server (NTRS)

Holley, L. D.; Ward, J. O. (Inventor)

1978-01-01

A circuit is described for adjusting the amplitude of a reference signal to a predetermined level so as to permit subsequent data signals to be interpreted correctly. The circuit includes an operational amplifier having a feedback circuit connected between an output terminal and an input terminal; a bank of relays operably connected to a plurality of resistors; and a comparator comparing an output voltage of the amplifier with a reference voltage and generating a compared signal responsive thereto. Means is provided for selectively energizing the relays according to the compared signal from the comparator until the output signal from the amplifier equals to the reference signal. A second comparator is provided for comparing the output of the amplifier with a second voltage source so as to illuminate a lamp when the output signal from the amplifier exceeds the second voltage.

Instability of phosphorous doped SiO2 in 4H-SiC MOS capacitors at high temperatures

NASA Astrophysics Data System (ADS)

Idris, M. I.; Weng, M. H.; Chan, H.-K.; Murphy, A. E.; Clark, D. T.; Young, R. A. R.; Ramsay, E. P.; Wright, N. G.; Horsfall, A. B.

2016-12-01

In this paper, the effect of inclusion of phosphorous (at a concentration below 1%) on the high temperature characteristics (up to 300 °C) of the SiO2/SiC interface is investigated. Capacitance-voltage measurements taken for a range of frequencies have been utilized to extract parameters including flatband voltage, threshold voltage, effective oxide charge, and interface state density. The variation of these parameters with temperature has been investigated for bias sweeps in opposing directions and a comparison made between phosphorous doped and as-grown oxides. At room temperature, the effective oxide charge for SiO2 may be reduced by the phosphorous termination of dangling bonds at the interface. However, at high temperatures, the effective charge in the phosphorous doped oxide remains unstable and effects such as flatband voltage shift and threshold voltage shift dominate the characteristics. The instability in these characteristics was found to result from the trapped charges in the oxide (±1012 cm-3) or near interface traps at the interface of the gate oxide and the semiconductor (1012-1013 cm-2 eV-1). Hence, the performance enhancements observed for phosphorous doped oxides are not realised in devices operated at elevated temperatures.

Potential damage to dc superconducting magnets due to high frequency electromagnetic waves

NASA Technical Reports Server (NTRS)

Gabriel, G. J.; Burkhart, J. A.

1977-01-01

Studies of a d.c. superconducting magnet coil indicate that the large coil behaves as a straight waveguide structure. Voltages between layers within the coil sometimes exceeded those recorded at terminals where protective resistors are located. Protection of magnet coils against these excessive voltages could be accomplished by impedance matching throughout the coil system. The wave phenomenon associated with superconducting magnetic coils may create an instability capable of converting the energy of a quiescent d.c. superconducting coil into dissipative a.c. energy, even in cases when dielectric breakdown does not take place.

C-terminal modulatory domain controls coupling of voltage-sensing to pore opening in Cav1.3 L-type Ca(2+) channels.

PubMed

Lieb, Andreas; Ortner, Nadine; Striessnig, Jörg

2014-04-01

Activity of voltage-gated Cav1.3 L-type Ca(2+) channels is required for proper hearing as well as sinoatrial node and brain function. This critically depends on their negative activation voltage range, which is further fine-tuned by alternative splicing. Shorter variants miss a C-terminal regulatory domain (CTM), which allows them to activate at even more negative potentials than C-terminally long-splice variants. It is at present unclear whether this is due to an increased voltage sensitivity of the Cav1.3 voltage-sensing domain, or an enhanced coupling of voltage-sensor conformational changes to the subsequent opening of the activation gate. We studied the voltage-dependence of voltage-sensor charge movement (QON-V) and of current activation (ICa-V) of the long (Cav1.3L) and a short Cav1.3 splice variant (Cav1.342A) expressed in tsA-201 cells using whole cell patch-clamp. Charge movement (QON) of Cav1.3L displayed a much steeper voltage-dependence and a more negative half-maximal activation voltage than Cav1.2 and Cav3.1. However, a significantly higher fraction of the total charge had to move for activation of Cav1.3 half-maximal conductance (Cav1.3: 68%; Cav1.2: 52%; Cav3.1: 22%). This indicated a weaker coupling of Cav1.3 voltage-sensor charge movement to pore opening. However, the coupling efficiency was strengthened in the absence of the CTM in Cav1.342A, thereby shifting ICa-V by 7.2 mV to potentials that were more negative without changing QON-V. We independently show that the presence of intracellular organic cations (such as n-methyl-D-glucamine) induces a pronounced negative shift of QON-V and a more negative activation of ICa-V of all three channels. These findings illustrate that the voltage sensors of Cav1.3 channels respond more sensitively to depolarization than those of Cav1.2 or Cav3.1. Weak coupling of voltage sensing to pore opening is enhanced in the absence of the CTM, allowing short Cav1.342A splice variants to activate at lower voltages without affecting QON-V. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

MULTIPLIER CIRCUIT

DOEpatents

Thomas, R.E.

1959-01-20

An electronic circuit is presented for automatically computing the product of two selected variables by multiplying the voltage pulses proportional to the variables. The multiplier circuit has a plurality of parallel resistors of predetermined values connected through separate gate circults between a first input and the output terminal. One voltage pulse is applied to thc flrst input while the second voltage pulse is applied to control circuitry for the respective gate circuits. Thc magnitude of the second voltage pulse selects the resistors upon which the first voltage pulse is imprcssed, whereby the resultant output voltage is proportional to the product of the input voltage pulses

Modeling development of converter topologies and control for BTB voltage source converters. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, L.

1998-08-01

This report presents the results of an investigation into the merits of using a back-to-back voltage source converter (BTB-VSC) as an alternative to a conventional back-to-back high voltage DC link (HVDC). The report presents the basic benefits of the new technology along with the basic control blocks needed to implement the design. The report also describes a model of the BTB-VSC implemented in EMTDC{trademark} and discusses the use of the model. Simulation results, showing how the model responds to various control actions and system disturbances, are presented. This modeling work developed a detailed EMTDC{trademark} model using the appropriate converter technologymore » and magnetic interface configuration. Various possible converter and magnetic interface configurations were examined and the most promising configuration was used for the model. The chosen configuration minimizes the number of high voltage transformers needed and minimizes the complexity non-standard interfacing transformers. There is no need for transformers with phase shifts other than zero or thirty degrees (wye-wye or wye-delta). The only non-standard feature is the necessity of bringing the neutral side of the high voltage winding on the wye-wye unit out through bushings and to insulate the wye-wye transformer for the system voltage which is twice the transformer winding voltage. The developed EMTDC{trademark} model was used to demonstrate the possibility of achieving independent control of the real power transmitted and the voltages at the AC terminals. The model also demonstrates the ability to interconnect weak AC systems without the necessity of additional voltage support equipment as is the case with the conventional back-to-back DC interconnection. The model has been shown to work with short circuit ratios less than 2 based on the total rating of the high voltage transformers.« less

H-terminated diamond field effect transistor with ferroelectric gate insulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karaya, Ryota; Furuichi, Hiroki; Nakajima, Takashi

2016-06-13

An H-terminated diamond field-effect-transistor (FET) with a ferroelectric vinylidene fluoride (VDF)-trifluoroethylene (TrFE) copolymer gate insulator was fabricated. The VDF-TrFE film was deposited on the H-terminated diamond by the spin-coating method and low-temperature annealing was performed to suppress processing damage to the H-terminated diamond surface channel layer. The fabricated FET structure showed the typical properties of depletion-type p-channel FET and showed clear saturation of the drain current with a maximum value of 50 mA/mm. The drain current versus gate voltage curves of the proposed FET showed clockwise hysteresis loops due to the ferroelectricity of the VDF-TrFE gate insulator, and the memory windowmore » width was 19 V, when the gate voltage was swept from 20 to −20 V. The maximum on/off current ratio and the linear mobility were 10{sup 8} and 398 cm{sup 2}/V s, respectively. In addition, we modulated the drain current of the fabricated FET structure via the remnant polarization of the VDF-TrFE gate and obtained an on/off current ratio of 10{sup 3} without applying a DC gate voltage.« less

Structure of a eukaryotic voltage-gated sodium channel at near-atomic resolution.

PubMed

Shen, Huaizong; Zhou, Qiang; Pan, Xiaojing; Li, Zhangqiang; Wu, Jianping; Yan, Nieng

2017-03-03

Voltage-gated sodium (Na v ) channels are responsible for the initiation and propagation of action potentials. They are associated with a variety of channelopathies and are targeted by multiple pharmaceutical drugs and natural toxins. Here, we report the cryogenic electron microscopy structure of a putative Na v channel from American cockroach (designated Na v PaS) at 3.8 angstrom resolution. The voltage-sensing domains (VSDs) of the four repeats exhibit distinct conformations. The entrance to the asymmetric selectivity filter vestibule is guarded by heavily glycosylated and disulfide bond-stabilized extracellular loops. On the cytoplasmic side, a conserved amino-terminal domain is placed below VSD I , and a carboxy-terminal domain binds to the III-IV linker. The structure of Na v PaS establishes an important foundation for understanding function and disease mechanism of Na v and related voltage-gated calcium channels. Copyright © 2017, American Association for the Advancement of Science.

Electrostatic Vibration Energy Harvester Pre-charged Wirelessly at 2.45 GHz

NASA Astrophysics Data System (ADS)

Saddi, Z.; Takhedmit, H.; Karami, A.; Basset, P.; Cirio, L.

2016-11-01

This paper reports the design, fabrication and experiments of an electrostatic vibration harvester (e-VEH), pre-charged wirelessly for the first time by using an electromagnetic waves harvester at 2.4 GHz. The rectenna uses the Cockcroft-Walton voltage doubler rectifier. It is designed and optimized to operate at low power densities and provides high voltage levels: 0.5 V at 0.5 μW/cm2 and 0.8 V at 1 μW/cm2 The e-VEH uses the Bennet doubler as conditioning circuit. Experiments show 23 V voltage across the transducer terminal when the harvester is excited at 25 Hz by 1.5 g of external acceleration. An accumulated energy of 275 μJ and a maximum power of 0.4 μW are available for the load.

The β1a Subunit of the Skeletal DHPR Binds to Skeletal RyR1 and Activates the Channel via Its 35-Residue C-Terminal Tail

PubMed Central

Rebbeck, Robyn T.; Karunasekara, Yamuna; Gallant, Esther M.; Board, Philip G.; Beard, Nicole A.; Casarotto, Marco G.; Dulhunty, Angela F.

2011-01-01

Although it has been suggested that the C-terminal tail of the β1a subunit of the skeletal dihyropyridine receptor (DHPR) may contribute to voltage-activated Ca2+ release in skeletal muscle by interacting with the skeletal ryanodine receptor (RyR1), a direct functional interaction between the two proteins has not been demonstrated previously. Such an interaction is reported here. A peptide with the sequence of the C-terminal 35 residues of β1a bound to RyR1 in affinity chromatography. The full-length β1a subunit and the C-terminal peptide increased [3H]ryanodine binding and RyR1 channel activity with an AC50 of 450–600 pM under optimal conditions. The effect of the peptide was dependent on cytoplasmic Ca2+, ATP, and Mg2+ concentrations. There was no effect of the peptide when channel activity was very low as a result of Mg2+ inhibition or addition of 100 nM Ca2+ (without ATP). Maximum increases were seen with 1–10 μM Ca2+, in the absence of Mg2+ inhibition. A control peptide with the C-terminal 35 residues in a scrambled sequence did not bind to RyR1 or alter [3H]ryanodine binding or channel activity. This high-affinity in vitro functional interaction between the C-terminal 35 residues of the DHPR β1a subunit and RyR1 may support an in vivo function of β1a during voltage-activated Ca2+ release. PMID:21320436

Frequency-dependent reliability of spike propagation is function of axonal voltage-gated sodium channels in cerebellar Purkinje cells.

PubMed

Yang, Zhilai; Wang, Jin-Hui

2013-12-01

The spike propagation on nerve axons, like synaptic transmission, is essential to ensure neuronal communication. The secure propagation of sequential spikes toward axonal terminals has been challenged in the neurons with a high firing rate, such as cerebellar Purkinje cells. The shortfall of spike propagation makes some digital spikes disappearing at axonal terminals, such that the elucidation of the mechanisms underlying spike propagation reliability is crucial to find the strategy of preventing loss of neuronal codes. As the spike propagation failure is influenced by the membrane potentials, this process is likely caused by altering the functional status of voltage-gated sodium channels (VGSC). We examined this hypothesis in Purkinje cells by using pair-recordings at their somata and axonal blebs in cerebellar slices. The reliability of spike propagation was deteriorated by elevating spike frequency. The frequency-dependent reliability of spike propagation was attenuated by inactivating VGSCs and improved by removing their inactivation. Thus, the functional status of axonal VGSCs influences the reliability of spike propagation.

Apparatus for the plasma destruction of hazardous gases

DOEpatents

Kang, M.

1995-02-07

A plasma cell for destroying hazardous gases is described. An electric-discharge cell having an electrically conducting electrode onto which an alternating high-voltage waveform is impressed and a dielectric barrier adjacent thereto, together forming a high-voltage electrode, generates self-terminating discharges throughout a volume formed between this electrode and a grounded conducting liquid electrode. The gas to be transformed is passed through this volume. The liquid may be flowed, generating thereby a renewable surface. Moreover, since hydrochloric and hydrofluoric acids may be formed from destruction of various chlorofluorocarbons in the presence of water, a conducting liquid may be selected which will neutralize these corrosive compounds. The gases exiting the discharge region may be further scrubbed if additional purification is required. 4 figs.

Apparatus for the plasma destruction of hazardous gases

DOEpatents

Kang, Michael

1995-01-01

A plasma cell for destroying hazardous gases. An electric-discharge cell having an electrically conducting electrode onto which an alternating high-voltage waveform is impressed and a dielectric barrier adjacent thereto, together forming a high-voltage electrode, generates self-terminating discharges throughout a volume formed between this electrode and a grounded conducting liquid electrode. The gas to be transformed is passed through this volume. The liquid may be flowed, generating thereby a renewable surface. Moreover, since hydrochloric and hydrofluoric acids may be formed from destruction of various chlorofluorocarbons in the presence of water, a conducting liquid may be selected which will neutralize these corrosive compounds. The gases exiting the discharge region may be further scrubbed if additional purification is required.

Novel design of high voltage pulse source for efficient dielectric barrier discharge generation by using silicon diodes for alternating current.

PubMed

Truong, Hoa Thi; Hayashi, Misaki; Uesugi, Yoshihiko; Tanaka, Yasunori; Ishijima, Tatsuo

2017-06-01

This work focuses on design, construction, and optimization of configuration of a novel high voltage pulse power source for large-scale dielectric barrier discharge (DBD) generation. The pulses were generated by using the high-speed switching characteristic of an inexpensive device called silicon diodes for alternating current and the self-terminated characteristic of DBD. The operation started to be powered by a primary DC low voltage power supply flexibly equipped with a commercial DC power supply, or a battery, or DC output of an independent photovoltaic system without transformer employment. This flexible connection to different types of primary power supply could provide a promising solution for the application of DBD, especially in the area without power grid connection. The simple modular structure, non-control requirement, transformer elimination, and a minimum number of levels in voltage conversion could lead to a reduction in size, weight, simple maintenance, low cost of installation, and high scalability of a DBD generator. The performance of this pulse source has been validated by a load of resistor. A good agreement between theoretically estimated and experimentally measured responses has been achieved. The pulse source has also been successfully applied for an efficient DBD plasma generation.

Novel design of high voltage pulse source for efficient dielectric barrier discharge generation by using silicon diodes for alternating current

NASA Astrophysics Data System (ADS)

Truong, Hoa Thi; Hayashi, Misaki; Uesugi, Yoshihiko; Tanaka, Yasunori; Ishijima, Tatsuo

2017-06-01

This work focuses on design, construction, and optimization of configuration of a novel high voltage pulse power source for large-scale dielectric barrier discharge (DBD) generation. The pulses were generated by using the high-speed switching characteristic of an inexpensive device called silicon diodes for alternating current and the self-terminated characteristic of DBD. The operation started to be powered by a primary DC low voltage power supply flexibly equipped with a commercial DC power supply, or a battery, or DC output of an independent photovoltaic system without transformer employment. This flexible connection to different types of primary power supply could provide a promising solution for the application of DBD, especially in the area without power grid connection. The simple modular structure, non-control requirement, transformer elimination, and a minimum number of levels in voltage conversion could lead to a reduction in size, weight, simple maintenance, low cost of installation, and high scalability of a DBD generator. The performance of this pulse source has been validated by a load of resistor. A good agreement between theoretically estimated and experimentally measured responses has been achieved. The pulse source has also been successfully applied for an efficient DBD plasma generation.

Transient AC voltage related phenomena for HVDC schemes connected to weak AC systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pilotto, L.A.S.; Szechtman, M.; Hammad, A.E.

1992-07-01

In this paper a didactic explanation of voltage stability associated phenomena at HVDC terminals is presented. Conditions leading to ac voltage collapse problems are identified. A mechanism that excites control-induced voltage oscillations is shown. The voltage stability factor is used for obtaining the maximum power limits of ac/dc systems operating with different control strategies. Correlation to Pd {times} Id curves is given. Solutions for eliminating the risks of voltage collapse and for avoiding control-induced oscillations are discussed. The results are supported by detailed digital simulations of a weak ac/dc system using EMTP.

A bi-stable nanoelectromechanical non-volatile memory based on van der Waals force

NASA Astrophysics Data System (ADS)

Soon, Bo Woon; Jiaqiang Ng, Eldwin; Qian, You; Singh, Navab; Julius Tsai, Minglin; Lee, Chengkuo

2013-07-01

By using complementary-metal-oxide-semiconductor processes, a silicon based bi-stable nanoelectromechanical non-volatile memory is fabricated and characterized. The main feature of this device is an 80 nm wide and 3 μm high silicon nanofin (SiNF) of a high aspect ratio (1:35). The switching mechanism is realized by electrostatic actuation between two lateral electrodes, i.e., terminals. Bi-stable hysteresis behavior is demonstrated when the SiNF maintains its contact to one of the two terminals by leveraging on van der Waals force even after voltage bias is turned off. The compelling results indicate that this design is promising for realization of high density non-volatile memory application due to its nano-scale footprint and zero on-hold power consumption.

METHOD OF LOCATING GROUNDS

DOEpatents

Macleish, K.G.

1958-02-11

ABS>This patent presents a method for locating a ground in a d-c circult having a number of parallel branches connected across a d-c source or generator. The complete method comprises the steps of locating the ground with reference to the mildpoint of the parallel branches by connecting a potentiometer across the terminals of the circuit and connecting the slider of the potentiometer to ground through a current indicating instrument, adjusting the slider to right or left of the mildpoint so as to cause the instrument to indicate zero, connecting the terminal of the network which is farthest from the ground as thus indicated by the potentiometer to ground through a condenser, impressing a ripple voltage on the circuit, and then measuring the ripple voltage at the midpoint of each parallel branch to find the branch in which is the lowest value of ripple voltage, and then measuring the distribution of the ripple voltage along this branch to determine the point at which the ripple voltage drops off to zero or substantially zero due to the existence of a ground. The invention has particular application where a circuit ground is present which will disappear if the normal circuit voltage is removed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bahder, G.; Bopp, L.A.; Eager, G.S.

This report covers the continuation of the work to develop technology to manufacture chemically crosslinked polyethylene insulated power cables in the ac voltage range of 138 kV to 345 kV having insulation thicknesses approximately equal to that of oil impregnated paper insulated cables. It also incorporates the development of field molded splices and terminations for new high voltage stress 138 kV cables. After reviewing the main equipment elements, incorporated in the pilot extrusion line, the special features of this system are noted and a step-by-step description of the cable extrusion process is given. Optimization of the process and introduction ofmore » modifications in the equipment culminated with the production of 138 kV cables. Results of laboratory tests to demonstrate the high quality of the cables are given. The development of molded splices and molded stress control cones was initiated with the work on model cables and followed by the making of splices and terminations on 138 kV cables. The molded components are made with the same purified insulating compound as used in the manufacture of the cables. Both the molded splices and the molded stress control cones have been fully tested in the laboratory. Following the completion of the development of the 138 kV cable a high stress 230 kV crosslinked polyethylene cable was developed and optimized. A full evaluation program similar to the one utilized on the 138 kV cable was carried out. Subsequently, work to develop a 345 kV high voltage stress cable, having insulation thickness of 1.02'' was undertaken. 345 kV cables were successfully manufactured and tested. However, additional work is required to further optimize the quality of this cable.« less

Noise Abatement Materials

NASA Technical Reports Server (NTRS)

1986-01-01

A former NASA employee who discovered a kind of plastic that soaked up energy, dampened vibrations, and was a good noise abatement material, founded a company to market noise deadening adhesives, sheets, panels and enclosures. Known as SMART products, they are 75-80% lighter than ordinary soundproofing material and have demonstrated a high degree of effectiveness. The company, Varian Associates, makes enclosures for high voltage terminals and other electronic system components, and easily transportable audiometric test booths.

Adenosine A1 receptors modulate high voltage-activated Ca2+ currents and motor pattern generation in the Xenopus embryo

PubMed Central

Brown, Paul; Dale, Nicholas

2000-01-01

Adenosine causes voltage- and non-voltage-dependent inhibition of high voltage-activated (HVA) Ca2+ currents in Xenopus laevis embryo spinal neurons. As this inhibition can be blocked by 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and mimicked by N6-cyclopentyladenosine (CPA) it appears to be mediated by A1 receptors. Agents active at A2 receptors either were without effect or could be blocked by DPCPX. AMP had no agonist action on these receptors. By using ω-conotoxin GVIA we found that adenosine inhibited an N-type Ca2+ current as well as a further unidentified HVA current that was insensitive to dihydropyridines, ω-agatoxin TK and ω-conotoxin MVIIC. Both types of current were subject to voltage- and non-voltage-dependent inhibition. We used CPA and DPCPX to test whether A1 receptors regulated spinal motor pattern generation in spinalized Xenopus embryos. DPCPX caused a near doubling of, while CPA greatly shortened, the length of swimming episodes. In addition, DPCPX slowed, while CPA greatly speeded up, the rate of run-down of motor activity. Our results demonstrate a novel action of A1 receptors in modulating spinal motor activity. Furthermore they confirm that adenosine is produced continually throughout swimming episodes and acts to cause the eventual termination of activity. PMID:10856119

Voltage-sensing domain mode shift is coupled to the activation gate by the N-terminal tail of hERG channels.

PubMed

Tan, Peter S; Perry, Matthew D; Ng, Chai Ann; Vandenberg, Jamie I; Hill, Adam P

2012-09-01

Human ether-a-go-go-related gene (hERG) potassium channels exhibit unique gating kinetics characterized by unusually slow activation and deactivation. The N terminus of the channel, which contains an amphipathic helix and an unstructured tail, has been shown to be involved in regulation of this slow deactivation. However, the mechanism of how this occurs and the connection between voltage-sensing domain (VSD) return and closing of the gate are unclear. To examine this relationship, we have used voltage-clamp fluorometry to simultaneously measure VSD motion and gate closure in N-terminally truncated constructs. We report that mode shifting of the hERG VSD results in a corresponding shift in the voltage-dependent equilibrium of channel closing and that at negative potentials, coupling of the mode-shifted VSD to the gate defines the rate of channel closure. Deletion of the first 25 aa from the N terminus of hERG does not alter mode shifting of the VSD but uncouples the shift from closure of the cytoplasmic gate. Based on these observations, we propose the N-terminal tail as an adaptor that couples voltage sensor return to gate closure to define slow deactivation gating in hERG channels. Furthermore, because the mode shift occurs on a time scale relevant to the cardiac action potential, we suggest a physiological role for this phenomenon in maximizing current flow through hERG channels during repolarization.

Fullerene-free small molecule organic solar cells with a high open circuit voltage of 1.15 V.

PubMed

Ni, Wang; Li, Miaomiao; Kan, Bin; Liu, Feng; Wan, Xiangjian; Zhang, Qian; Zhang, Hongtao; Russell, Thomas P; Chen, Yongsheng

2016-01-11

A new small molecule named DTBTF with thiobarbituric acid as a terminal group was designed and synthesized as an acceptor for organic photovoltaic applications. DTBTF exhibits strong absorption in the visible region, and a relatively high lying LUMO energy level (-3.62 eV). All-small-molecule organic solar cells based on DR3TSBDT:DTBTF blend films show a considerable PCE of 3.84% with a high V(oc) of 1.15 V.

Functional Properties of a Newly Identified C-terminal Splice Variant of Cav1.3 L-type Ca2+ Channels*

PubMed Central

Bock, Gabriella; Gebhart, Mathias; Scharinger, Anja; Jangsangthong, Wanchana; Busquet, Perrine; Poggiani, Chiara; Sartori, Simone; Mangoni, Matteo E.; Sinnegger-Brauns, Martina J.; Herzig, Stefan; Striessnig, Jörg; Koschak, Alexandra

2011-01-01

An intramolecular interaction between a distal (DCRD) and a proximal regulatory domain (PCRD) within the C terminus of long Cav1.3 L-type Ca2+ channels (Cav1.3L) is a major determinant of their voltage- and Ca2+-dependent gating kinetics. Removal of these regulatory domains by alternative splicing generates Cav1.342A channels that activate at a more negative voltage range and exhibit more pronounced Ca2+-dependent inactivation. Here we describe the discovery of a novel short splice variant (Cav1.343S) that is expressed at high levels in the brain but not in the heart. It lacks the DCRD but, in contrast to Cav1.342A, still contains PCRD. When expressed together with α2δ1 and β3 subunits in tsA-201 cells, Cav1.343S also activated at more negative voltages like Cav1.342A but Ca2+-dependent inactivation was less pronounced. Single channel recordings revealed much higher channel open probabilities for both short splice variants as compared with Cav1.3L. The presence of the proximal C terminus in Cav1.343S channels preserved their modulation by distal C terminus-containing Cav1.3- and Cav1.2-derived C-terminal peptides. Removal of the C-terminal modulation by alternative splicing also induced a faster decay of Ca2+ influx during electrical activities mimicking trains of neuronal action potentials. Our findings extend the spectrum of functionally diverse Cav1.3 L-type channels produced by tissue-specific alternative splicing. This diversity may help to fine tune Ca2+ channel signaling and, in the case of short variants lacking a functional C-terminal modulation, prevent excessive Ca2+ accumulation during burst firing in neurons. This may be especially important in neurons that are affected by Ca2+-induced neurodegenerative processes. PMID:21998310

Charged residues distribution modulates selectivity of the open state of human isoforms of the voltage dependent anion-selective channel.

PubMed

Amodeo, Giuseppe Federico; Scorciapino, Mariano Andrea; Messina, Angela; De Pinto, Vito; Ceccarelli, Matteo

2014-01-01

Voltage Dependent Anion-selective Channels (VDACs) are pore-forming proteins located in the outer mitochondrial membrane. They are responsible for the access of ions and energetic metabolites into the inner membrane transport systems. Three VDAC isoforms exist in mammalian, but their specific role is unknown. In this work we have performed extensive (overall ∼5 µs) Molecular Dynamics (MD) simulations of the human VDAC isoforms to detect structural and conformational variations among them, possibly related to specific functional roles of these proteins. Secondary structure analysis of the N-terminal domain shows a high similarity among the three human isoforms of VDAC but with a different plasticity. In particular, the N-terminal domain of the hVDAC1 is characterized by a higher plasticity, with a ∼20% occurrence for the 'unstructured' conformation throughout the folded segment, while hVDAC2, containing a peculiar extension of 11 amino acids at the N-terminal end, presents an additional 310-helical folded portion comprising residues 10' to 3, adhering to the barrel wall. The N-terminal sequences of hVDAC isoforms are predicted to have a low flexibility, with possible consequences in the dynamics of the human VDACs. Clear differences were found between hVDAC1 and hVDAC3 against hVDAC2: a significantly modified dynamics with possible important consequence on the voltage-gating mechanism. Charge distribution inside and at the mouth of the pore is responsible for a different preferential localization of ions with opposite charge and provide a valuable rationale for hVDAC1 and hVDAC3 having a Cl-/K+ selectivity ratio of 1.8, whereas hVDAC2 of 1.4. Our conclusion is that hVDAC isoforms, despite sharing a similar scaffold, have modified working features and a biological work is now requested to give evidence to the described dissimilarities.

Morphological and physiological analysis of type-5 and other bipolar cells in the Mouse Retina.

PubMed

Hellmer, C B; Zhou, Y; Fyk-Kolodziej, B; Hu, Z; Ichinose, T

2016-02-19

Retinal bipolar cells are second-order neurons in the visual system, which initiate multiple image feature-based neural streams. Among more than ten types of bipolar cells, type-5 cells are thought to play a role in motion detection pathways. Multiple subsets of type-5 cells have been reported; however, detailed characteristics of each subset have not yet been elucidated. Here, we found that they exhibit distinct morphological features as well as unique voltage-gated channel expression. We have conducted electrophysiological and immunohistochemical analysis of retinal bipolar cells. We defined type-5 cells by their axon terminal ramification in the inner plexiform layer between the border of ON/OFF sublaminae and the ON choline acetyltransferase (ChAT) band. We found three subsets of type-5 cells: XBCs had the widest axon terminals that stratified at a close approximation of the ON ChAT band as well as exhibiting large voltage-gated Na(+) channel activity, type-5-1 cells had compact terminals and no Na(+) channel activity, and type-5-2 cells contained umbrella-shaped terminals as well as large voltage-gated Na(+) channel activity. Hyperpolarization-activated cyclic nucleotide-gated (HCN) currents were also evoked in all type-5 bipolar cells. We found that XBCs and type-5-2 cells exhibited larger HCN currents than type-5-1 cells. Furthermore, the former two types showed stronger HCN1 expression than the latter. Our previous observations (Ichinose et al., 2014) match the current study: low temporal tuning cells that we named 5S corresponded to 5-1 in this study, while high temporal tuning 5f cells from the previous study corresponded to 5-2 cells. Taken together, we found three subsets of type-5 bipolar cells based on their morphologies and physiological features. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

High stability amplifier

NASA Technical Reports Server (NTRS)

Adams, W. A.; Reinhardt, V. S. (Inventor)

1983-01-01

An electrical RF signal amplifier for providing high temperature stability and RF isolation and comprised of an integrated circuit voltage regulator, a single transistor, and an integrated circuit operational amplifier mounted on a circuit board such that passive circuit elements are located on side of the circuit board while the active circuit elements are located on the other side is described. The active circuit elements are embedded in a common heat sink so that a common temperature reference is provided for changes in ambient temperature. The single transistor and operational amplifier are connected together to form a feedback amplifier powered from the voltage regulator with transistor implementing primarily the desired signal gain while the operational amplifier implements signal isolation. Further RF isolation is provided by the voltage regulator which inhibits cross-talk from other like amplifiers powered from a common power supply. Input and output terminals consisting of coaxial connectors are located on the sides of a housing in which all the circuit components and heat sink are located.

High voltage isolation transformer

NASA Technical Reports Server (NTRS)

Clatterbuck, C. H.; Ruitberg, A. P. (Inventor)

1985-01-01

A high voltage isolation transformer is provided with primary and secondary coils separated by discrete electrostatic shields from the surfaces of insulating spools on which the coils are wound. The electrostatic shields are formed by coatings of a compound with a low electrical conductivity which completely encase the coils and adhere to the surfaces of the insulating spools adjacent to the coils. Coatings of the compound also line axial bores of the spools, thereby forming electrostatic shields separating the spools from legs of a ferromagnetic core extending through the bores. The transformer is able to isolate a high constant potential applied to one of its coils, without the occurrence of sparking or corona, by coupling the coatings, lining the axial bores to the ferromagnetic core and by coupling one terminal of each coil to the respective coating encasing the coil.

High voltage isolation transformer

NASA Astrophysics Data System (ADS)

Clatterbuck, C. H.; Ruitberg, A. P.

1985-04-01

A high voltage isolation transformer is provided with primary and secondary coils separated by discrete electrostatic shields from the surfaces of insulating spools on which the coils are wound. The electrostatic shields are formed by coatings of a compound with a low electrical conductivity which completely encase the coils and adhere to the surfaces of the insulating spools adjacent to the coils. Coatings of the compound also line axial bores of the spools, thereby forming electrostatic shields separating the spools from legs of a ferromagnetic core extending through the bores. The transformer is able to isolate a high constant potential applied to one of its coils, without the occurrence of sparking or corona, by coupling the coatings, lining the axial bores to the ferromagnetic core and by coupling one terminal of each coil to the respective coating encasing the coil.

Voltage-induced swelling and deswelling of weak polybase brushes.

PubMed

Weir, Michael P; Heriot, Sasha Y; Martin, Simon J; Parnell, Andrew J; Holt, Stephen A; Webster, John R P; Jones, Richard A L

2011-09-06

We have investigated a novel method of remotely switching the conformation of a weak polybase brush using an applied voltage. Surface-grafted polyelectrolyte brushes exhibit rich responsive behavior and show great promise as "smart surfaces", but existing switching methods involve physically or chemically changing the solution in contact with the brush. In this study, high grafting density poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes were grown from silicon surfaces using atom transfer radical polymerization. Optical ellipsometry and neutron reflectivity were used to measure changes in the profiles of the brushes in response to DC voltages applied between the brush substrate and a parallel electrode some distance away in the surrounding liquid (water or D(2)O). Positive voltages were shown to cause swelling, while negative voltages in some cases caused deswelling. Neutron reflectometry experiments were carried out on the INTER reflectometer (ISIS, Rutherford Appleton Laboratory, UK) allowing time-resolved measurements of polymer brush structure. The PDMAEMA brushes were shown to have a polymer volume fraction profile described by a Gaussian-terminated parabola both in the equilibrium and in the partially swollen states. At very high positive voltages (in this study, positive bias means positive voltage to the brush-bearing substrate), the brush chains were shown to be stretched to an extent comparable to their contour length, before being physically removed from the interface. Voltage-induced swelling was shown to exhibit a wider range of brush swelling states in comparison to pH switching, with the additional advantages that the stimulus is remotely controlled and may be fully automated. © 2011 American Chemical Society

A gating grid driver for time projection chambers

NASA Astrophysics Data System (ADS)

Tangwancharoen, S.; Lynch, W. G.; Barney, J.; Estee, J.; Shane, R.; Tsang, M. B.; Zhang, Y.; Isobe, T.; Kurata-Nishimura, M.; Murakami, T.; Xiao, Z. G.; Zhang, Y. F.; SπRIT Collaboration

2017-05-01

A simple but novel driver system has been developed to operate the wire gating grid of a Time Projection Chamber (TPC). This system connects the wires of the gating grid to its driver via low impedance transmission lines. When the gating grid is open, all wires have the same voltage allowing drift electrons, produced by the ionization of the detector gas molecules, to pass through to the anode wires. When the grid is closed, the wires have alternating higher and lower voltages causing the drift electrons to terminate at the more positive wires. Rapid opening of the gating grid with low pickup noise is achieved by quickly shorting the positive and negative wires to attain the average bias potential with N-type and P-type MOSFET switches. The circuit analysis and simulation software SPICE shows that the driver restores the gating grid voltage to 90% of the opening voltage in less than 0.20 μs, for small values of the termination resistors. When tested in the experimental environment of a time projection chamber larger termination resistors were chosen so that the driver opens the gating grid in 0.35 μs. In each case, opening time is basically characterized by the RC constant given by the resistance of the switches and terminating resistors and the capacitance of the gating grid and its transmission line. By adding a second pair of N-type and P-type MOSFET switches, the gating grid is closed by restoring 99% of the original charges to the wires within 3 μs.

Parts, Materials, and Processes Control Program for Expendable Launch Vehicles

DTIC Science & Technology

2015-07-31

burn-in, electrical tests (DWV, room and hot IR, partial discharge when in corona region); perform DPA with SEM/EDX analysis of dielectric...life test; x-ray and vicinal illumination inspection; electrical tests (DWV, room and hot IR, partial discharge when in corona region) Termination...defects; proper voltage derating. Partial discharge testing, corona inception testing up to 60% of rated voltage; CSAM screening; voltage burn

Reversing-counterpulse repetitive-pulse inductive storage circuit

DOEpatents

Honig, Emanuel M.

1987-01-01

A high-power reversing-counterpulse repetitive-pulse inductive storage and transfer circuit includes an opening switch, a main energy storage coil, a counterpulse capacitor and a small inductor. After counterpulsing the opening switch off, the counterpulse capacitor is recharged by the main energy storage coil before the load pulse is initiated. This gives the counterpulse capacitor sufficient energy for the next counterpulse operation, although the polarity of the capacitor's voltage must be reversed before that can occur. By using a current-zero switch as the counterpulse start switch, the capacitor is disconnected from the circuit (with a full charge) when the load pulse is initiated, preventing the capacitor from depleting its energy store by discharging through the load. After the load pulse is terminated by reclosing the main opening switch, the polarity of the counterpulse capacitor voltage is reversed by discharging the capacitor through a small inductor and interrupting the discharge current oscillation at zero current and peak reversed voltage. The circuit enables high-power, high-repetition-rate operation with reusable switches and features total control (pulse-to-pulse) over output pulse initiation, duration, repetition rate, and, to some extent, risetime.

Reversing-counterpulse repetitive-pulse inductive storage circuit

DOEpatents

Honig, E.M.

1984-06-05

A high power reversing-counterpulse repetitive-pulse inductive storage and transfer circuit includes an opening switch, a main energy storage coil, a counterpulse capacitor and a small inductor. After counterpulsing the opening switch off, the counterpulse capacitor is recharged by the main energy storage coil before the load pulse is initiated. This gives the counterpulse capacitor sufficient energy for the next counterpulse operation, although the polarity of the capacitor's voltage must be reversed before that can occur. By using a current-zero switch as the counterpulse start switch, the capacitor is disconnected from the circuit (with a full charge) when the load pulse is initiated, preventing the capacitor from depleting its energy store by discharging through the load. After the load pulse is terminated by reclosing the main opening switch, the polarity of the counterpulse capacitor voltage is reversed by discharging the capacitor through a small inductor and interrupting the discharge current oscillation at zero current and peak reversed voltage. The circuit enables high-power, high-repetition-rate operation with reusable switches and features total control (pulse-to-pulse) over output pulse initiation, duration, repetition rate, and, to some extent, risetime.

Effects of insulator ablation on the operation of a quasi-steady MPD arc

NASA Technical Reports Server (NTRS)

Boyle, M. J.; Jahn, R. G.

1973-01-01

Multimegawatt operation of quasi-steady MPD arcjets can involve serious ablation of the insulator surfaces within the arc discharge chamber. Various degrees of insulator ablation manifest themselves by significantly perturbing the voltage-current characteristics and the exhaust velocity profiles. Voltage-current characteristics for two different insulator materials, Plexiglas and boron nitride, are interpreted in terms of an empirical Ohm's law. Use of the refractory insulator material eliminates the ablation-dominated nature of the terminal voltage, but the exhaust stream is still disturbed by insulator material. An Alfven critical velocity model can be applied to this influence of insulator ablation on exhaust velocity. Appropriate changes in the propellant injection geometry eliminate this influence and result in arcjet operation which is independent of insulator material. A particular combination of propellant injection geometries reduces the terminal voltage for a given current and mass flow while maintaining insulator-independent operation, thus implying an improvement in the overall efficiency of the device.

Monolithically integrated Si gate-controlled light-emitting device: science and properties

NASA Astrophysics Data System (ADS)

Xu, Kaikai

2018-02-01

The motivation of this study is to develop a p-n junction based light emitting device, in which the light emission is conventionally realized using reverse current driving, by voltage driving. By introducing an additional terminal of insulated gate for voltage driving, a novel three-terminal Si light emitting device is described where both the light intensity and spatial light pattern of the device are controlled by the gate voltage. The proposed light emitting device employs injection-enhanced Si in avalanche mode where electric field confinement occurs in the corner of a reverse-biased p+n junction. It is found that, depending on the bias conditions, the light intensity is either a linear or a quadratic function of the applied gate voltage or the reverse-bias. Since the light emission is based on the avalanching mode, the Si light emitting device offers the potential for very large scale integration-compatible light emitters for inter- or intra-chip signal transmission and contactless functional testing of wafers.

Nuclear instrumentation cable end seal

DOEpatents

Cannon, Collins P.; Brown, Donald P.

1979-01-01

An improved coaxial end seal for hermetically sealed nuclear instrumentation cable exhibiting an improved breakdown pulse noise characteristic under high voltage, high temperature conditions. A tubular insulator body has metallized interior and exterior surface portions which are braze sealed to a center conductor and an outer conductive sheath. The end surface of the insulator body which is directed toward the coaxial cable to which it is sealed has a recessed surface portion within which the braze seal material terminates.

Large-scale collision cross-section profiling on a travelling wave ion mobility mass spectrometer

PubMed Central

Lietz, Christopher B.; Yu, Qing; Li, Lingjun

2014-01-01

Ion mobility (IM) is a gas-phase electrophoretic method that separates ions according to charge and ion-neutral collision cross-section (CCS). Herein, we attempt to apply a travelling wave (TW) IM polyalanine calibration method to shotgun proteomics and create a large peptide CCS database. Mass spectrometry methods that utilize IM, such as HDMSE, often use high transmission voltages for sensitive analysis. However, polyalanine calibration has only been demonstrated with low voltage transmission used to prevent gas-phase activation. If polyalanine ions change conformation under higher transmission voltages used for HDMSE, the calibration may no longer be valid. Thus, we aimed to characterize the accuracy of calibration and CCS measurement under high transmission voltages on a TW IM instrument using the polyalanine calibration method and found that the additional error was not significant. We also evaluated the potential error introduced by liquid chromatography (LC)-HDMSE analysis, and found it to be insignificant as well, validating the calibration method. Finally, we demonstrated the utility of building a large-population peptide CCS database by investigating the effects of terminal lysine position, via LysC or LysN digestion, on the formation of two structural sub-families formed by triply charged ions. PMID:24845359

Fast electrochemical actuator

NASA Astrophysics Data System (ADS)

Uvarov, I. V.; Postnikov, A. V.; Svetovoy, V. B.

2016-03-01

Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics.

The NH2 terminus regulates voltage-dependent gating of CALHM ion channels.

PubMed

Tanis, Jessica E; Ma, Zhongming; Foskett, J Kevin

2017-08-01

Calcium homeostasis modulator protein-1 (CALHM1) and its Caenorhabditis elegans (ce) homolog, CLHM-1, belong to a new family of physiologically important ion channels that are regulated by voltage and extracellular Ca 2+ (Ca 2+ o ) but lack a canonical voltage-sensing domain. Consequently, the intrinsic voltage-dependent gating mechanisms for CALHM channels are unknown. Here, we performed voltage-clamp experiments on ceCLHM-1 chimeric, deletion, insertion, and point mutants to assess the role of the NH 2 terminus (NT) in CALHM channel gating. Analyses of chimeric channels in which the ceCLHM-1 and human (h)CALHM1 NH 2 termini were interchanged showed that the hCALHM1 NT destabilized channel-closed states, whereas the ceCLHM-1 NT had a stabilizing effect. In the absence of Ca 2+ o , deletion of up to eight amino acids from the ceCLHM-1 NT caused a hyperpolarizing shift in the conductance-voltage relationship with little effect on voltage-dependent slope. However, deletion of nine or more amino acids decreased voltage dependence and induced a residual conductance at hyperpolarized voltages. Insertion of amino acids into the NH 2 -terminal helix also decreased voltage dependence but did not prevent channel closure. Mutation of ceCLHM-1 valine 9 and glutamine 13 altered half-maximal activation and voltage dependence, respectively, in 0 Ca 2+ In 2 mM Ca 2+ o , ceCLHM-1 NH 2 -terminal deletion and point mutant channels closed completely at hyperpolarized voltages with apparent affinity for Ca 2+ o indistinguishable from wild-type ceCLHM-1, although the ceCLHM-1 valine 9 mutant exhibited an altered conductance-voltage relationship and kinetics. We conclude that the NT plays critical roles modulating voltage dependence and stabilizing the closed states of CALHM channels. Copyright © 2017 the American Physiological Society.

Source-drain burnout mechanism of GaAs power MESFETS: Three terminal effects

NASA Astrophysics Data System (ADS)

Takamiya, Saburo; Sonoda, Takuji; Yamanouchi, Masahide; Fujioka, Takashi; Kohno, Masaki

1997-03-01

Theoretical expressions for thermal and electrical feedback effects are derived. These limit the power capability of a power FET and lead a device to catastrophic breakdown (source-drain burnout) when the loop gain of the former reaches unity. Field emission of thermally excited electrons at the Schottky gate plays the key role in thermal feedback, while holes being impact ionized by the drain current play a similar role in the electrical feedback. Thermal feedback is dominant in a high temperature and low drain voltage area. Electrical feedback is dominant in a high drain voltage and low temperature area. In the first area, a high junction temperature is the main factor causing the thermal runaway of the device. In the second area, the electrcal feedback increases the drain current and the temperature and gives a trigger to the thermal feedback so that it reaches unity more easily. Both effects become significant in proportion to transconductance and gate bias resistance, and cause simultaneous runaway of the gate and drain currents. The expressions of the loop gains clearly indicate the safe operating conditions for a power FET. C-band 4 W (1 chip) and 16 W (4 chip) GaAs MESFETs were used as the experimental samples. With these devices the simultaneous runaway of the gate and the drain currents, apparent dependence of the three teminal breakdown voltage on the gate bias resistance in the region dominated by electrical feedback, the rapid increase of the field emitted current at the critical temperature and clear coincidence between the measured and calculated three terminal gate currents both in the thermal feedback dominant region, etc. are demonstrated. The theory explains the experimental results well.

Lithium battery discharge tests

NASA Technical Reports Server (NTRS)

Johnson, C. J.

1980-01-01

The long term discharge of a variety of lithium cells was characterized and the susceptibility of the cells to chemical variation during the slow discharge was tested. A shunt resistor was set across the terminals to monitor the voltage as a function of time. Failures were identified by premature voltage drops.

Hyperpolarization-activated current (I(h)) in vestibular calyx terminals: characterization and role in shaping postsynaptic events.

PubMed

Meredith, Frances L; Benke, Tim A; Rennie, Katherine J

2012-12-01

Calyx afferent terminals engulf the basolateral region of type I vestibular hair cells, and synaptic transmission across the vestibular type I hair cell/calyx is not well understood. Calyces express several ionic conductances, which may shape postsynaptic potentials. These include previously described tetrodotoxin-sensitive inward Na(+) currents, voltage-dependent outward K(+) currents and a K(Ca) current. Here, we characterize an inwardly rectifying conductance in gerbil semicircular canal calyx terminals (postnatal days 3-45), sensitive to voltage and to cyclic nucleotides. Using whole-cell patch clamp, we recorded from isolated calyx terminals still attached to their type I hair cells. A slowly activating, noninactivating current (I(h)) was seen with hyperpolarizing voltage steps negative to the resting potential. External Cs(+) (1-5 mM) and ZD7288 (100 μM) blocked the inward current by 97 and 83 %, respectively, confirming that I(h) was carried by hyperpolarization-activated, cyclic nucleotide gated channels. Mean half-activation voltage of I(h) was -123 mV, which shifted to -114 mV in the presence of cAMP. Activation of I(h) was well described with a third order exponential fit to the current (mean time constant of activation, τ, was 190 ms at -139 mV). Activation speeded up significantly (τ=136 and 127 ms, respectively) when intracellular cAMP and cGMP were present, suggesting that in vivo I(h) could be subject to efferent modulation via cyclic nucleotide-dependent mechanisms. In current clamp, hyperpolarizing current steps produced a time-dependent depolarizing sag followed by either a rebound afterdepolarization or an action potential. Spontaneous excitatory postsynaptic potentials (EPSPs) became larger and wider when I(h) was blocked with ZD7288. In a three-dimensional mathematical model of the calyx terminal based on Hodgkin-Huxley type ionic conductances, removal of I(h) similarly increased the EPSP, whereas cAMP slightly decreased simulated EPSP size and width.

A Biologically Constrained, Mathematical Model of Cortical Wave Propagation Preceding Seizure Termination

PubMed Central

González-Ramírez, Laura R.; Ahmed, Omar J.; Cash, Sydney S.; Wayne, C. Eugene; Kramer, Mark A.

2015-01-01

Epilepsy—the condition of recurrent, unprovoked seizures—manifests in brain voltage activity with characteristic spatiotemporal patterns. These patterns include stereotyped semi-rhythmic activity produced by aggregate neuronal populations, and organized spatiotemporal phenomena, including waves. To assess these spatiotemporal patterns, we develop a mathematical model consistent with the observed neuronal population activity and determine analytically the parameter configurations that support traveling wave solutions. We then utilize high-density local field potential data recorded in vivo from human cortex preceding seizure termination from three patients to constrain the model parameters, and propose basic mechanisms that contribute to the observed traveling waves. We conclude that a relatively simple and abstract mathematical model consisting of localized interactions between excitatory cells with slow adaptation captures the quantitative features of wave propagation observed in the human local field potential preceding seizure termination. PMID:25689136

A high voltage dielectrically isolated smart power technology based on silicon direct bonding

NASA Astrophysics Data System (ADS)

Macary, Veronique

1992-09-01

The feasibility of a dielectrically isolated technology based on the silicon direct bonding technique, for high voltage smart power applications in the 1000 to 1550 V/1 to 20 A range, where a vertical power switch is necessary, is investigated and demonstrated. Static and dynamic isolation of the low voltage circuitry integrated beside the vertical power transistor is the main concern of this family of circuits. The dielectric isolation offers better protection to the low voltage part than does the junction isolation, because of the elimination of the parasitic bipolar transistor inherent to the latter isolation technique. Silicon direct bonding provides a cost effective way to obtain a buried oxide isolation layer. In addition, the application requires a Si/Si bonded area in the active region of the vertical power switch. Strong influence of the prebonding cleaning in the electrical characteristics of the Si/Si interface is pointed out, and presence of crystalline defects is assumed to be at the origin of electrical failures. The main problems of silicon direct bonding process compatibility with standard processes were overcome, and a complete process flow, including the simultaneous integration of a vertical power bipolar transistor together with a bipolar control circuitry, was validated. Using a peripheral biased ring is shown to provide an easy way to optimize high voltage termination for the smart power circuit, while adding a non-additional technological step. This technique was studied by dimensional electrical simulations (BIDIM2 software), as well as analytically computed.

An AlN/Al 0.85Ga 0.15N high electron mobility transistor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.

2016-07-22

An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al 0.85Ga 0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high I on/I off current ratio greater than 10 7 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. In conclusion,more » the room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.« less

Electric eels use high-voltage to track fast-moving prey

PubMed Central

Catania, Kenneth C.

2015-01-01

Electric eels (Electrophorus electricus) are legendary for their ability to incapacitate fish, humans, and horses with hundreds of volts of electricity. The function of this output as a weapon has been obvious for centuries but its potential role for electroreception has been overlooked. Here it is shown that electric eels use high-voltage simultaneously as a weapon and for precise and rapid electrolocation of fast-moving prey and conductors. Their speed, accuracy, and high-frequency pulse rate are reminiscent of bats using a ‘terminal feeding buzz' to track insects. Eel's exhibit ‘sensory conflict' when mechanosensory and electrosensory cues are separated, striking first toward mechanosensory cues and later toward conductors. Strikes initiated in the absence of conductors are aborted. In addition to providing new insights into the evolution of strongly electric fish and showing electric eels to be far more sophisticated than previously described, these findings reveal a trait with markedly dichotomous functions. PMID:26485580

Investigation of Re-X glass ceramic for acceleration insulating columns

NASA Astrophysics Data System (ADS)

Faltens, A.; Rosenblum, S.

1985-05-01

In an induction linac the accelerating voltage appears along a voltage-graded vacuum insulator column which is a performance limiting and major cost component. Re-X glass ceramic insulators have the long-sought properties of allowing cast-in gradient electrodes, good breakdown characteristics, and compatibility with high vacuum systems. Re-X is a glass ceramic developed by General Electric for use in the manufacture of electrical apparatus, such as vacuum arc interrupters. We have examined vacuum outgassing behavior and voltage breakdown in vacuum and find excellent performance. The housings are in the shape of tubes with type 430 stainless steel terminations. Due to a matched coefficient of thermal expansion between metal and insulator, no vacuum leaks have resulted from any welding operation. The components should be relatively inexpensive to manufacture in large sizes and appear to be a very attractive accelerator column. We are planning to use a standard GE housing in our MBE-4 induction linac.

Pulsed electromagnetic gas acceleration. [magnetohydrodynamics, plasma power sources and plasma propulsion

NASA Technical Reports Server (NTRS)

Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

1975-01-01

Terminal voltage measurements with various cathodes and anodes in a high power, quasi-steady magnetoplasmadynamic (MPD) are discussed. The magnitude of the current at the onset of voltage fluctuations is shown to be an increasing function of cathode area and a weaker decreasing function of anode area. Tests with a fluted cathode indicated that the fluctuations originate in the plasma adjacent to the cathode rather than at the cathode surface. Measurements of radiative output from an optical cavity aligned to examine the current-carrying portion of a two-dimensional, 56 kA magnetoplasmadynamic discharge reveal no lasing in that region, consistent with calculations of electron excitation and resonance radiation trapping. A voltage-swept double probe technique allows single-shot determination of electron temperature and electron number density in the recombining MPD exhaust flow. Current distributions within the cavity of MPD hollow cathodes for various static prefills with no injected mass flow are examined.

A novel ultrasonic clutch using near-field acoustic levitation.

PubMed

Chang, Kuo-Tsi

2004-10-01

This paper investigates design, fabrication and drive of an ultrasonic clutch with two transducers. For the two transducers, one serving as a driving element of the clutch is connected to a driving shaft via a coupling, and the other serving as a slave element of the clutch is connected to a slave shaft via another coupling. The principle of ultrasonic levitation is first expressed. Then, a series-resonant inverter is used to generate AC voltages at input terminals of each transducer, and a speed measuring system with optic sensors is used to find the relationship between rotational speed of the slave shaft and applied voltage of each transducer. Moreover, contact surfaces of the two transducers are coupled by the frictional force when both the two transducers are not energized, and separated using the ultrasonic levitation when at least one of the two transducers is energized at high voltages at resonance.

Vertical GaN power diodes with a bilayer edge termination

DOE PAGES

Dickerson, Jeramy R.; Allerman, Andrew A.; Bryant, Benjamin N.; ...

2015-12-07

Vertical GaN power diodes with a bilayer edge termination (ET) are demonstrated. The GaN p-n junction is formed on a low threading dislocation defect density (10 4 - 10 5 cm -2) GaN substrate, and has a 15-μm-thick n-type drift layer with a free carrier concentration of 5 × 10 15 cm -3. The ET structure is formed by N implantation into the p+-GaN epilayer just outside the p-type contact to create compensating defects. The implant defect profile may be approximated by a bilayer structure consisting of a fully compensated layer near the surface, followed by a 90% compensated (p)more » layer near the n-type drift region. These devices exhibit avalanche breakdown as high as 2.6 kV at room temperature. In addition simulations show that the ET created by implantation is an effective way to laterally distribute the electric field over a large area. This increases the voltage at which impact ionization occurs and leads to the observed higher breakdown voltages.« less

The C-terminal coiled-coil of the bacterial voltage-gated sodium channel NaChBac is not essential for tetramer formation, but stabilizes subunit-to-subunit interactions.

PubMed

Mio, Kazuhiro; Mio, Muneyo; Arisaka, Fumio; Sato, Masahiko; Sato, Chikara

2010-09-01

The NaChBac is a prokaryotic homologue of the voltage-gated sodium channel found in the genome of the alkalophilic bacterium Bacillus halodurans C-125. Like a repeating cassette of mammalian sodium channel, the NaChBac possesses hydrophobic domains corresponding to six putative transmembrane segments and a pore loop, and exerts channel function by forming a tetramer although detailed mechanisms of subunit assembly remain unclear. We generated truncated mutants from NaChBac, and investigated their ability to form tetramers in relation to their channel functions. A mutant that deletes almost all of the C-terminal coiled-coil structure lost its voltage-dependent ion permeability, although it was properly translocated to the cell surface. The mutant protein was purified as a tetramer using a reduced concentration of detergent, but the association between the subunits was shown to be much weaker than the wild type. The chemical cross-linking, blue native PAGE, sedimentation velocity experiments, size exclusion chromatography, immunoprecipitation, and electron microscopy all supported its tetrameric assembly. We further purified the C-terminal cytoplasmic domain alone and confirmed its self-oligomerization. These data suggest that the C-terminal coiled-coil structure stabilizes subunit-to-subunit interactions of NaChBac, but is not critical for their tetramer formation. 2010 Elsevier Ltd. All rights reserved.

Electrical leakage detection circuit

DOEpatents

Wild, Arthur

2006-09-05

A method is provided for detecting electrical leakage between a power supply and a frame of a vehicle or machine. The disclosed method includes coupling a first capacitor between a frame and a first terminal of a power supply for a predetermined period of time. The current flowing between the frame and the first capacitor is limited to a predetermined current limit. It is determined whether the voltage across the first capacitor exceeds a threshold voltage. A first output signal is provided when the voltage across the capacitor exceeds the threshold voltage.

Gaseous Electronics Conference (35th) Held at Dallas, Texas, 19-22 October 1982.

DTIC Science & Technology

1982-12-31

Hz LTE arcs con- taining mrury and metal halide additives such as Nal and Sc13 . , Using a well defined cylindrical arc vessel and a known mercury ...termination of the high pressure mercury arc will be presented. 1 F.E. Irons, J.Quant.Spect.Radiat.Transfer 22,1,(1979). 41IBLANK I- CA-3 Time Dependent...High pressure mercury lamps were. operated on a perioically pulsed supply voltage. From optically thin mercury line emission the variation of the axial

Analyzing Single-Event Gate Ruptures In Power MOSFET's

NASA Technical Reports Server (NTRS)

Zoutendyk, John A.

1993-01-01

Susceptibilities of power metal-oxide/semiconductor field-effect transistors (MOSFET's) to single-event gate ruptures analyzed by exposing devices to beams of energetic bromine ions while applying appropriate bias voltages to source, gate, and drain terminals and measuring current flowing into or out of each terminal.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Wencan; Vishwanath, Suresh; Liu, Jianpeng

Topological crystalline insulators have been recently predicted and observed in rock-salt structure SnSe {111} thin films. Previous studies have suggested that the Se-terminated surface of this thin film with hydrogen passivation has a reduced surface energy and is thus a preferred configuration. In this paper, synchrotron-based angle-resolved photoemission spectroscopy, along with density functional theory calculations, is used to demonstrate that a rock-salt SnSe {111} thin film epitaxially grown on Bi 2Se 3 has a stable Sn-terminated surface. These observations are supported by low-energy electron diffraction (LEED) intensity-voltage measurements and dynamical LEED calculations, which further show that the Sn-terminated SnSe {111}more » thin film has undergone a surface structural relaxation of the interlayer spacing between the Sn and Se atomic planes. In sharp contrast to the Se-terminated counterpart, the observed Dirac surface state in the Sn-terminated SnSe {111} thin film is shown to yield a high Fermi velocity, 0.50 x 10 6 m/s, which suggests a potential mechanism of engineering the Dirac surface state of topological materials by tuning the surface configuration.« less

The pH-sensitive structure of the C-terminal domain of voltage-gated proton channel and the thermodynamic characteristics of Zn{sup 2+} binding to this domain

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Qing; Li, Chuanyong; Li, Shu Jie, E-mail: shujieli@nankai.edu.cn

2015-01-02

Highlights: • The α-helical content of the C-terminus is decreased with a pH increase. • The thermostability of the C-terminus is decreased with a pH increase. • Zn{sup 2+} binds to His{sup 244} and His{sup 266} residues within the C-terminal domain. • The binding of Zn{sup 2+} to His{sup 244} residue is an endothermic heat reaction. • The binding of Zn{sup 2+} to His{sup 266} residue is an exothermic heat reaction. - Abstract: The voltage-gated proton channel Hv1 is strongly sensitive to Zn{sup 2+}. The H{sup +} conduction is decreased at a high concentration of Zn{sup 2+} and Hv1 channelmore » closing is slowed by the internal application of Zn{sup 2+}. Although the recent studies demonstrated that Zn{sup 2+} interacts with the intracellular C-terminal domain, the binding sites and details of the interaction remain unknown. Here, we studied the pH-dependent structural stability of the intracellular C-terminal domain of human Hv1 and showed that Zn{sup 2+} binds to His{sup 244} and His{sup 266} residues. The thermodynamics signature of Zn{sup 2+} binding to the two sites was investigated by isothermal titration calorimetry. The binding of Zn{sup 2+} to His{sup 244} (mutant H266A) and His{sup 266} (mutant H244A) were an endothermic heat reaction and an exothermic heat reaction, respectively.« less

Electric field control in DC cable test termination by nano silicone rubber composite

NASA Astrophysics Data System (ADS)

Song, Shu-Wei; Li, Zhongyuan; Zhao, Hong; Zhang, Peihong; Han, Baozhong; Fu, Mingli; Hou, Shuai

2017-07-01

The electric field distributions in high voltage direct current cable termination are investigated with silicone rubber nanocomposite being the electric stress control insulator. The nanocomposite is composed of silicone rubber, nanoscale carbon black and graphitic carbon. The experimental results show that the physical parameters of the nanocomposite, such as thermal activation energy and nonlinearity-relevant coefficient, can be manipulated by varying the proportion of the nanoscale fillers. The numerical simulation shows that safe electric field distribution calls for certain parametric region of the thermal activation energy and nonlinearity-relevant coefficient. Outside the safe parametric region, local maximum of electric field strength around the stress cone appears in the termination insulator, enhancing the breakdown of the cable termination. In the presence of the temperature gradient, thermal activation energy and nonlinearity-relevant coefficient work as complementary factors to produce a reasonable electric field distribution. The field maximum in the termination insulator show complicate variation in the transient processes. The stationary field distribution favors the increase of the nonlinearity-relevant coefficient; for the transient field distribution in the process of negative lighting impulse, however, an optimized value of the nonlinearity-relevant coefficient is necessary to equalize the electric field in the termination.

Comparative evaluation of power factor impovement techniques for squirrel cage induction motors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spee, R.; Wallace, A.K.

1992-04-01

This paper describes the results obtained from a series of tests of relatively simple methods of improving the power factor of squirrel-cage induction motors. The methods, which are evaluated under controlled laboratory conditions for a 10-hp, high-efficiency motor, include terminal voltage reduction; terminal static capacitors; and a floating'' winding with static capacitors. The test results are compared with equivalent circuit model predictions that are then used to identify optimum conditions for each of the power factor improvement techniques compared with the basic induction motor. Finally, the relative economic value, and the implications of component failures, of the three methods aremore » discussed.« less

A New MPPT Control for Photovoltaic Panels by Instantaneous Maximum Power Point Tracking

NASA Astrophysics Data System (ADS)

Tokushima, Daiki; Uchida, Masato; Kanbei, Satoshi; Ishikawa, Hiroki; Naitoh, Haruo

This paper presents a new maximum power point tracking control for photovoltaic (PV) panels. The control can be categorized into the Perturb and Observe (P & O) method. It utilizes instantaneous voltage ripples at PV panel output terminals caused by the switching of a chopper connected to the panel in order to identify the direction for the maximum power point (MPP). The tracking for the MPP is achieved by a feedback control of the average terminal voltage of the panel. Appropriate use of the instantaneous and the average values of the PV voltage for the separate purposes enables both the quick transient response and the good convergence with almost no ripples simultaneously. The tracking capability is verified experimentally with a 2.8 W PV panel under a controlled experimental setup. A numerical comparison with a conventional P & O confirms that the proposed control extracts much more power from the PV panel.

SDVSRM - a new SSRM based technique featuring dynamically adjusted, scanner synchronized sample voltages for measurement of actively operated devices.

PubMed

Doering, Stefan; Wachowiak, Andre; Roetz, Hagen; Eckl, Stefan; Mikolajick, Thomas

2018-06-01

Scanning spreading resistance microscopy (SSRM) with its high spatial resolution and high dynamic signal range is a powerful tool for two-dimensional characterization of semiconductor dopant areas. However, the application of the method is limited to devices in equilibrium condition, as the investigation of actively operated devices would imply potential differences within the device, whereas SSRM relies on a constant voltage difference between sample surface and probe tip. Furthermore, the standard preparation includes short circuiting of all device components, limiting applications to devices in equilibrium condition. In this work scanning dynamic voltage spreading resistance microscopy (SDVSRM), a new SSRM based two pass atomic force microscopy (AFM) technique is introduced, overcoming these limitations. Instead of short circuiting the samples during preparation, wire bond devices are used allowing for active control of the individual device components. SDVSRM consists of two passes. In the first pass the local sample surface voltage dependent on the dc biases applied to the components of the actively driven device is measured as in scanning voltage microscopy (SVM). The local spreading resistance is measured within the second pass, in which the afore obtained local surface voltage is used to dynamically adjust the terminal voltages of the device under test. This is done in a way that the local potential difference across the nano-electrical contact matches the software set SSRM measurement voltage, and at the same time, the internal voltage differences within the device under test are maintained. In this work the proof of the concept could be demonstrated by obtaining spreading resistance data of an actively driven photodiode test device. SDVSRM adds a higher level of flexibility in general to SSRM, as occurring differences in cross section surface voltage are taken into account. These differences are immanent for actively driven devices, but can also be present at standard, short circuited samples. Therefore, SDVSRM could improve the characterization under equilibrium conditions as well. Copyright © 2018. Published by Elsevier B.V.

High-Voltage Power Supply With Fast Rise and Fall Times

NASA Technical Reports Server (NTRS)

Bearden, Douglas B.; Acker, Richard M.; Kapuslka, Robert E.

2007-01-01

A special-purpose high-voltage power supply can be electronically switched on and off with fast rise and fall times, respectively. The output potential is programmable from 20 to 1,250 V. An output current of 50 A can be sustained at 1,250 V. The power supply was designed specifically for electronically shuttering a microchannel plate in an x-ray detector that must operate with exposure times as short as 1 ms. The basic design of the power supply is also adaptable to other applications in which there are requirements for rapid slewing of high voltages. The power-supply circuitry (see figure) includes a preregulator, which is used to program the output at 1/30 of the desired output potential. After the desired voltage has been set, the outputs of a pulse width modulator (PWM) are enabled and used to amplify the preregulator output potential by 30. The amplification is achieved by use of two voltage doublers with a transformer that has two primary and two secondary windings. A resistor is used to limit the current by controlling the drive voltage of two field-effect transistors (FETs) during turn-on of the PWM. A pulse transformer is used to turn on four FETs to short-circuit four output capacitors when the outputs of the PWM have been disabled. The most notable aspects of the performance of the power supply are a rise time of only 80 s and a fall time of only 60 s at a load current of 50 A or less. Another notable aspect is that the application of a 0-to-5-V square wave to a shutdown pin of the PWM causes the production of a 0-to-1,250-V square wave at the output terminals.

Reversing-counterpulse repetitive-pulse inductive storage circuit

DOEpatents

Honig, E.M.

1987-02-10

A high-power reversing-counterpulse repetitive-pulse inductive storage and transfer circuit includes an opening switch, a main energy storage coil, a counterpulse capacitor and a small inductor. After counterpulsing the opening switch off, the counterpulse capacitor is recharged by the main energy storage coil before the load pulse is initiated. This gives the counterpulse capacitor sufficient energy for the next counterpulse operation, although the polarity of the capacitor's voltage must be reversed before that can occur. By using a current-zero switch as the counterpulse start switch, the capacitor is disconnected from the circuit (with a full charge) when the load pulse is initiated, preventing the capacitor from depleting its energy store by discharging through the load. After the load pulse is terminated by reclosing the main opening switch, the polarity of the counterpulse capacitor voltage is reversed by discharging the capacitor through a small inductor and interrupting the discharge current oscillation at zero current and peak reversed voltage. The circuit enables high-power, high-repetition-rate operation with reusable switches and features total control (pulse-to-pulse) over output pulse initiation, duration, repetition rate, and, to some extent, risetime. 10 figs.

Analysis of Ti valence states in resistive switching regions of a rutile TiO2‑ x four-terminal memristive device

NASA Astrophysics Data System (ADS)

Yamaguchi, Kengo; Takeuchi, Shotaro; Tohei, Tetsuya; Ikarashi, Nobuyuki; Sakai, Akira

2018-06-01

We have performed Ti valence state analysis of our four-terminal rutile TiO2‑ x single-crystal memristors using scanning transmission electron microscopy–electron energy loss spectroscopy (STEM–EELS). Analysis of Ti-L2,3 edge EELS spectra revealed that the electrocolored region formed by the application of voltage includes a valence state reflecting highly reduced TiO2‑ x due to the accumulation of oxygen vacancies. Such a valence state mainly exists within ∼50 nm from the crystal surface and extends along specific crystal directions. These electrically reduced surface layers are considered to directly contribute to the resistive switching (RS) in the four-terminal device. The present results add new insights into the microscopic mechanisms of the RS phenomena and should contribute to further development and improvements of TiO2‑ x based memristive devices.

Hybrid AC-High Voltage DC Grid Stability and Controls

NASA Astrophysics Data System (ADS)

Yu, Jicheng

The growth of energy demands in recent years has been increasing faster than the expansion of transmission facility construction. This tendency cooperating with the continuous investing on the renewable energy resources drives the research, development, and construction of HVDC projects to create a more reliable, affordable, and environmentally friendly power grid. Constructing the hybrid AC-HVDC grid is a significant move in the development of the HVDC techniques; the form of dc system is evolving from the point-to-point stand-alone dc links to the embedded HVDC system and the multi-terminal HVDC (MTDC) system. The MTDC is a solution for the renewable energy interconnections, and the MTDC grids can improve the power system reliability, flexibility in economic dispatches, and converter/cable utilizing efficiencies. The dissertation reviews the HVDC technologies, discusses the stability issues regarding the ac and HVDC connections, proposes a novel power oscillation control strategy to improve system stability, and develops a nonlinear voltage droop control strategy for the MTDC grid. To verify the effectiveness the proposed power oscillation control strategy, a long distance paralleled AC-HVDC transmission test system is employed. Based on the PSCAD/EMTDC platform simulation results, the proposed power oscillation control strategy can improve the system dynamic performance and attenuate the power oscillations effectively. To validate the nonlinear voltage droop control strategy, three droop controls schemes are designed according to the proposed nonlinear voltage droop control design procedures. These control schemes are tested in a hybrid AC-MTDC system. The hybrid AC-MTDC system, which is first proposed in this dissertation, consists of two ac grids, two wind farms and a five-terminal HVDC grid connecting them. Simulation studies are performed in the PSCAD/EMTDC platform. According to the simulation results, all the three design schemes have their unique salient features.

An improved adaptive weighting function method for State Estimation in Power Systems with VSC-MTDC

NASA Astrophysics Data System (ADS)

Zhao, Kun; Yang, Xiaonan; Lang, Yansheng; Song, Xuri; Wang, Minkun; Luo, Yadi; Wu, Lingyun; Liu, Peng

2017-04-01

This paper presents an effective approach for state estimation in power systems that include multi-terminal voltage source converter based high voltage direct current (VSC-MTDC), called improved adaptive weighting function method. The proposed approach is simplified in which the VSC-MTDC system is solved followed by the AC system. Because the new state estimation method only changes the weight and keeps the matrix dimension unchanged. Accurate and fast convergence of AC/DC system can be realized by adaptive weight function method. This method also provides the technical support for the simulation analysis and accurate regulation of AC/DC system. Both the oretical analysis and numerical tests verify practicability, validity and convergence of new method.

Electronic inverter assembly with an integral snubber capacitor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Brij N.; Schmit, Christopher J.

A coaxial bus connector has a first end and a second end opposite the first end. The first end has a first positive terminal and a first negative terminal coupled to a primary direct current bus of a primary inverter. The second end has a second positive terminal and a second negative terminal coupled to the secondary direct current bus of a secondary inverter, wherein the coaxial bus connector comprises a dielectric material between a center conductor and a coaxial sleeve to form a snubber capacitor to absorb electrical energy or to absorb voltage spikes.

Functional properties of a newly identified C-terminal splice variant of Cav1.3 L-type Ca2+ channels.

PubMed

Bock, Gabriella; Gebhart, Mathias; Scharinger, Anja; Jangsangthong, Wanchana; Busquet, Perrine; Poggiani, Chiara; Sartori, Simone; Mangoni, Matteo E; Sinnegger-Brauns, Martina J; Herzig, Stefan; Striessnig, Jörg; Koschak, Alexandra

2011-12-09

An intramolecular interaction between a distal (DCRD) and a proximal regulatory domain (PCRD) within the C terminus of long Ca(v)1.3 L-type Ca(2+) channels (Ca(v)1.3(L)) is a major determinant of their voltage- and Ca(2+)-dependent gating kinetics. Removal of these regulatory domains by alternative splicing generates Ca(v)1.3(42A) channels that activate at a more negative voltage range and exhibit more pronounced Ca(2+)-dependent inactivation. Here we describe the discovery of a novel short splice variant (Ca(v)1.3(43S)) that is expressed at high levels in the brain but not in the heart. It lacks the DCRD but, in contrast to Ca(v)1.3(42A), still contains PCRD. When expressed together with α2δ1 and β3 subunits in tsA-201 cells, Ca(v)1.3(43S) also activated at more negative voltages like Ca(v)1.3(42A) but Ca(2+)-dependent inactivation was less pronounced. Single channel recordings revealed much higher channel open probabilities for both short splice variants as compared with Ca(v)1.3(L). The presence of the proximal C terminus in Ca(v)1.3(43S) channels preserved their modulation by distal C terminus-containing Ca(v)1.3- and Ca(v)1.2-derived C-terminal peptides. Removal of the C-terminal modulation by alternative splicing also induced a faster decay of Ca(2+) influx during electrical activities mimicking trains of neuronal action potentials. Our findings extend the spectrum of functionally diverse Ca(v)1.3 L-type channels produced by tissue-specific alternative splicing. This diversity may help to fine tune Ca(2+) channel signaling and, in the case of short variants lacking a functional C-terminal modulation, prevent excessive Ca(2+) accumulation during burst firing in neurons. This may be especially important in neurons that are affected by Ca(2+)-induced neurodegenerative processes.

Study of a High Voltage Ion Engine Power Supply

NASA Technical Reports Server (NTRS)

Stuart, Thomas A.; King, Roger J.; Mayer, Eric

1996-01-01

A complete laboratory breadboard version of a ion engine power converter was built and tested. This prototype operated on a line voltage of 80-120 Vdc, and provided output ratings of 1100 V at 1.8 kW, and 250 V at 20 mA. The high-voltage (HV) output voltage rating was revised from the original value of 1350 V at the beginning of the project. The LV output was designed to hold up during a 1-A surge current lasting up to 1 second. The prototype power converter included a internal housekeeping power supply which also operated from the line input. The power consumed in housekeeping was included in the overall energy budget presented for the ion engine converter. HV and LV output voltage setpoints were commanded through potentiometers. The HV converter itself reached its highest power efficiency of slightly over 93% at low line and maximum output. This would dip below 90% at high line. The no-load (rated output voltages, zero load current) power consumption of the entire system was less than 13 W. A careful loss breakdown shows that converter losses are predominately Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) conduction losses and HV rectifier snubbing losses, with the rectifier snubbing losses becoming predominant at high line. This suggests that further improvements in power efficiency could best be obtained by either developing a rectifier that was adequately protected against voltage overshoot with less snubbing, or by developing a pre-regulator to reduced the range of line voltage on the converter. The transient testing showed the converter to be fully protected against load faults, including a direct short-circuit from the HV output to the LV output terminals. Two currents sensors were used: one to directly detect any core ratcheting on the output transformer and re-initiate a soft start, and the other to directly detect a load fault and quickly shut down the converter for load protection. The finished converter has been extensively fault tested without failure. The finished converter has been packaged suitable for use as a laboratory prototype for further testing. The finished converter is readily transportable. An article on design issues for high voltage converters for ion engines is included as an attachement.

Over-voltage protection system and method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chi, Song; Dong, Dong; Lai, Rixin

An over-voltage protection system includes an electronic valve connected across two terminals of a circuit and an over-voltage detection circuit connected across one of the plurality of semiconductor devices for detecting an over-voltage across the circuit. The electronic valve includes a plurality of semiconductor devices connected in series. The over-voltage detection circuit includes a voltage divider circuit connected to a break-over diode in a way to provide a representative low voltage to the break-over diode and an optocoupler configured to receive a current from the break-over diode when the representative low voltage exceeds a threshold voltage of the break-over diodemore » indicating an over-voltage condition. The representative low voltage provided to the break-over diode represents a voltage across the one semiconductor device. A plurality of self-powered gate drive circuits are connected to the plurality of semiconductor devices, wherein the plurality of self-powered gate drive circuits receive over-voltage triggering pulses from the optocoupler during the over-voltage condition and switch on the plurality of semiconductor devices to bypass the circuit.« less

Chaotic behaviors of operational amplifiers.

PubMed

Yim, Geo-Su; Ryu, Jung-Wan; Park, Young-Jai; Rim, Sunghwan; Lee, Soo-Young; Kye, Won-Ho; Kim, Chil-Min

2004-04-01

We investigate nonlinear dynamical behaviors of operational amplifiers. When the output terminal of an operational amplifier is connected to the inverting input terminal, the circuit exhibits period-doubling bifurcation, chaos, and periodic windows, depending on the voltages of the positive and the negative power supplies. We study these nonlinear dynamical characteristics of this electronic circuit experimentally.

C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1.

PubMed

Mumm, Patrick; Imes, Dennis; Martinoia, Enrico; Al-Rasheid, Khaled A S; Geiger, Dietmar; Marten, Irene; Hedrich, Rainer

2013-09-01

Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

A Fresh Look at the Semiconductor Bandgap Using Constant Current Data

ERIC Educational Resources Information Center

Ocaya, R. O.; Luhanga, P. V. C.

2011-01-01

It is shown that the well-known linear variation of p-n diode terminal voltage with temperature at different fixed forward currents allows easy and accurate determination of the semiconductor ideality factor and bandgap from only two data points. This is possible if the temperature difference required to maintain the same diode voltage drop can be…

System and method for charging electrochemical cells in series

DOEpatents

DeLuca, William H.; Hornstra, Jr, Fred; Gelb, George H.; Berman, Baruch; Moede, Larry W.

1980-01-01

A battery charging system capable of equalizing the charge of each individual cell at a selected full charge voltage includes means for regulating charger current to first increase current at a constant rate until a bulk charging level is achieved or until any cell reaches a safe reference voltage. A system controller then begins to decrease the charging rate as long as any cell exceeds the reference voltage until an equalization current level is reached. At this point, the system controller activates a plurality of shunt modules to permit shunting of current around any cell having a voltage exceeding the reference voltage. Leads extending between the battery of cells and shunt modules are time shared to permit alternate shunting of current and voltage monitoring without the voltage drop caused by the shunt current. After each cell has at one time exceeded the reference voltage, the charging current is terminated.

Frontier applications of electrostatic accelerators

NASA Astrophysics Data System (ADS)

Liu, Ke-Xin; Wang, Yu-Gang; Fan, Tie-Shuan; Zhang, Guo-Hui; Chen, Jia-Er

2013-10-01

Electrostatic accelerator is a powerful tool in many research fields, such as nuclear physics, radiation biology, material science, archaeology and earth sciences. Two electrostatic accelerators, one is the single stage Van de Graaff with terminal voltage of 4.5 MV and another one is the EN tandem with terminal voltage of 6 MV, were installed in 1980s and had been put into operation since the early 1990s at the Institute of Heavy Ion Physics. Many applications have been carried out since then. These two accelerators are described and summaries of the most important applications on neutron physics and technology, radiation biology and material science, as well as accelerator mass spectrometry (AMS) are presented.

Splice connector with internal heat transfer jacket

DOEpatents

Silva, Frank A.; Mayer, Robert W.

1977-01-01

A heat transfer jacket is placed over the terminal portions of the conductors of a pair of high voltage cables which are connected in a splice connection wherein a housing surrounds the connected conductor portions, the heat transfer jacket extending longitudinally between the confronting ends of a pair of adaptor sleeves placed upon the insulation of the cables to engage and locate the adaptor sleeves relative to one another, and laterally between the conductors and the housing to provide a path of relatively high thermal conductivity between the connected conductor portions and the housing.

High-Voltage, High-Power Gaseous Electronics Switch For Electric Grid Power Conversion

NASA Astrophysics Data System (ADS)

Sommerer, Timothy J.

2014-05-01

We are developing a high-voltage, high-power gas switch for use in low-cost power conversion terminals on the electric power grid. Direct-current (dc) power transmission has many advantages over alternating current (ac) transmission, but at present the high cost of ac-dc power interconversion limits the use of dc. The gas switch we are developing conducts current through a magnetized cold cathode plasma in hydrogen or helium to reach practical current densities > 1 A/cm2. Thermal and sputter damage of the cathode by the incident ion flux is a major technical risk, and is being addressed through use of a ``self-healing'' liquid metal cathode (eg, gallium). Plasma conditions and cathode sputtering loss are estimated by analyzing plasma spectral emission. A particle-in-cell plasma model is used to understand various aspects of switch operation, including the conduction phase (where plasma densities can exceed 1013 cm-3), the switch-open phase (where the high-voltage must be held against gas breakdown on the left side of Paschen's curve), and the switching transitions (especially the opening process, which is initiated by forming an ion-matrix sheath adjacent to a control grid). The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

High-rate/high-temperature capability of a single-layer zicar-separator nickel-hydrogen cell

NASA Technical Reports Server (NTRS)

Wheeler, James R.

1995-01-01

A 50 Ampere-hour nickel-hydrogen cell with a single-layer Zircar separator stack design was fully charged and then discharged at a 2C current rate to an end voltage of 1 volt. This extreme test resulted in high temperatures which were recorded at three locations on the cell, i.e., the cell wall, the boss (barrel of the compression seal), and a terminal. The results provide new information about the high-temperature and high-discharge-rate capabilities of nickel-hydrogen cells. This information also adds to the growing data base for single-layer zirconium-oxide-cloth (Zircar) separator cell designs.

Al0 0.3Ga 0.7N PN diode with breakdown voltage >1600 V

DOE PAGES

Allerman, A. A.; Armstrong, A. M.; Fischer, A. J.; ...

2016-07-21

Demonstration of Al0 0.3Ga 0.7N PN diodes grown with breakdown voltages in excess of 1600 V is reported. The total epilayer thickness is 9.1 μm and was grown by metal-organic vapour-phase epitaxy on 1.3-mm-thick sapphire in order to achieve crack-free structures. A junction termination edge structure was employed to control the lateral electric fields. A current density of 3.5 kA/cm 2 was achieved under DC forward bias and a reverse leakage current <3 nA was measured for voltages <1200 V. The differential on-resistance of 16 mΩ cm 2 is limited by the lateral conductivity of the n-type contact layer requiredmore » by the front-surface contact geometry of the device. An effective critical electric field of 5.9 MV/cm was determined from the epilayer properties and the reverse current–voltage characteristics. To our knowledge, this is the first aluminium gallium nitride (AlGaN)-based PN diode exhibiting a breakdown voltage in excess of 1 kV. Finally, we note that a Baliga figure of merit (V br 2/R spec,on) of 150 MW/cm 2 found is the highest reported for an AlGaN PN diode and illustrates the potential of larger-bandgap AlGaN alloys for high-voltage devices.« less

Numerical Simulation on the Induced Voltage Across the Coil Terminal by the Segmented Flow of Ferrofluid and Air-Layer.

PubMed

Lee, Won-Ho; Lee, Sangyoup; Lee, Jong-Chul

2018-09-01

Nanoparticles and nanofluids have been implemented in energy harvesting devices, and energy harvesting based on magnetic nanofluid flow was recently achieved by using a layer-built magnet and microbubble injection to induce a voltage on the order of 10-1 mV. However, this is not yet suitable for some commercial purpose. The air bubbles must be segmented in the base fluid, and the magnetic flux of the ferrofluids should change over time to increase the amount of electric voltage and current from energy harvesting. In this study, we proposed a novel technique to achieve segmented flow of the ferrofluids and the air layers. This segmented ferrofluid flow linear generator can increase the magnitude of the induced voltage from the energy harvesting system. In our experiments, a ferrofluid-filled capsule produced time-dependent changes in the magnetic flux through a multi-turn coil, and the induced voltage was generated on the order of about 101 mV at a low frequency of 2 Hz. A finite element analysis was used to describe the time-dependent change of the magnetic flux through the coil according to the motion of the segmented flow of the ferrofluid and the air-layer, and the induced voltage was generated to the order of 102 mV at a high frequency of 12.5 Hz.

Electronic Structure of the Metastable Epitaxial Rock-Salt SnSe {111 } Topological Crystalline Insulator

NASA Astrophysics Data System (ADS)

Jin, Wencan; Vishwanath, Suresh; Liu, Jianpeng; Kong, Lingyuan; Lou, Rui; Dai, Zhongwei; Sadowski, Jerzy T.; Liu, Xinyu; Lien, Huai-Hsun; Chaney, Alexander; Han, Yimo; Cao, Michael; Ma, Junzhang; Qian, Tian; Wang, Shancai; Dobrowolska, Malgorzata; Furdyna, Jacek; Muller, David A.; Pohl, Karsten; Ding, Hong; Dadap, Jerry I.; Xing, Huili Grace; Osgood, Richard M.

2017-10-01

Topological crystalline insulators have been recently predicted and observed in rock-salt structure SnSe {111 } thin films. Previous studies have suggested that the Se-terminated surface of this thin film with hydrogen passivation has a reduced surface energy and is thus a preferred configuration. In this paper, synchrotron-based angle-resolved photoemission spectroscopy, along with density functional theory calculations, is used to demonstrate that a rock-salt SnSe {111 } thin film epitaxially grown on Bi2Se3 has a stable Sn-terminated surface. These observations are supported by low-energy electron diffraction (LEED) intensity-voltage measurements and dynamical LEED calculations, which further show that the Sn-terminated SnSe {111 } thin film has undergone a surface structural relaxation of the interlayer spacing between the Sn and Se atomic planes. In sharp contrast to the Se-terminated counterpart, the observed Dirac surface state in the Sn-terminated SnSe {111 } thin film is shown to yield a high Fermi velocity, 0.50 ×106 m /s , which suggests a potential mechanism of engineering the Dirac surface state of topological materials by tuning the surface configuration.

Electronic Structure of the Metastable Epitaxial Rock-Salt SnSe { 111 } Topological Crystalline Insulator

DOE PAGES

Jin, Wencan; Vishwanath, Suresh; Liu, Jianpeng; ...

2017-10-25

Topological crystalline insulators have been recently predicted and observed in rock-salt structure SnSe {111} thin films. Previous studies have suggested that the Se-terminated surface of this thin film with hydrogen passivation has a reduced surface energy and is thus a preferred configuration. In this paper, synchrotron-based angle-resolved photoemission spectroscopy, along with density functional theory calculations, is used to demonstrate that a rock-salt SnSe {111} thin film epitaxially grown on Bi 2Se 3 has a stable Sn-terminated surface. These observations are supported by low-energy electron diffraction (LEED) intensity-voltage measurements and dynamical LEED calculations, which further show that the Sn-terminated SnSe {111}more » thin film has undergone a surface structural relaxation of the interlayer spacing between the Sn and Se atomic planes. In sharp contrast to the Se-terminated counterpart, the observed Dirac surface state in the Sn-terminated SnSe {111} thin film is shown to yield a high Fermi velocity, 0.50 x 10 6 m/s, which suggests a potential mechanism of engineering the Dirac surface state of topological materials by tuning the surface configuration.« less

Dissipation, Voltage Profile and Levy Dragon in a Special Ladder Network

ERIC Educational Resources Information Center

Ucak, C.

2009-01-01

A ladder network constructed by an elementary two-terminal network consisting of a parallel resistor-inductor block in series with a parallel resistor-capacitor block sometimes is said to have a non-dispersive dissipative response. This special ladder network is created iteratively by replacing the elementary two-terminal network in place of the…

A Complex Permittivity Based Sensor for the Electrical Characterization of High-Voltage Transformer Oils

PubMed Central

Dervos, Constantine T.; Paraskevas, Christos D.; Skafidas, Panayotis D.; Vassiliou, Panayota

2005-01-01

This work investigates the use of a specially designed cylindrical metal cell, in order to obtain complex permittivity and tanδ data of highly insulating High Voltage (HV) transformer oil samples. The data are obtained at a wide range of frequencies and operation temperatures to demonstrate the polarization phenomena and the thermally stimulated effects. Such complex permittivity measurements may be utilized as a criterion for the service life prediction of oil field electrical equipment (OFEE). Therefore, by one set of measurements on a small oil volume, data may be provided on the impending termination, or continuation of the transformer oil service life. The oil incorporating cell, attached to the appropriate measuring units, could be described as a complex permittivity sensor. In this work, the acquired dielectric data from a great number of operating distribution network power transformers were correlated to corresponding physicochemical ones to demonstrate the future potential employment of the proposed measuring technique.

Current-voltage characteristics and increase in the quantum efficiency of three-terminal gate and avalanche-based silicon LEDs.

PubMed

Xu, Kaikai

2013-09-20

In this paper, the emission of visible light by a monolithically integrated silicon p-n junction under reverse-bias is discussed. The modulation of light intensity is achieved using an insulated-gate terminal on the surface of the p-n junction. By varying the gate voltage, the breakdown voltage of the p-n junction will be adjustable so that the reverse current I(sub) flowing through the p-n junction at a fixed reverse-bias voltage is changed. It is observed that the light, which is emitted from the defects located at the p-n junction, depends closely on the reverse current I(sub). In regard to the phenomenon of electroluminescence, the relationship between the optical emission power and the reverse current I(sub) is linear. On the other hand, it is observed that both the quantum efficiency and the power conversion efficiency are able to have obvious enhancement, although the reverse-bias of the p-n junction is reduced and the corresponding reverse-current is much lower. Moreover, the successful fabrication on monolithic silicon light source on the bulk silicon by means of standard silicon complementary metal-oxide-semiconductor process technology is presented.

TMEM16A is associated with voltage-gated calcium channels in mouse retina and its function is disrupted upon mutation of the auxiliary α2δ4 subunit

PubMed Central

Caputo, Antonella; Piano, Ilaria; Demontis, Gian Carlo; Bacchi, Niccolò; Casarosa, Simona; Santina, Luca Della; Gargini, Claudia

2015-01-01

Photoreceptors rely upon highly specialized synapses to efficiently transmit signals to multiple postsynaptic targets. Calcium influx in the presynaptic terminal is mediated by voltage-gated calcium channels (VGCC). This event triggers neurotransmitter release, but also gates calcium-activated chloride channels (TMEM), which in turn regulate VGCC activity. In order to investigate the relationship between VGCC and TMEM channels, we analyzed the retina of wild type (WT) and Cacna2d4 mutant mice, in which the VGCC auxiliary α2δ4 subunit carries a nonsense mutation, disrupting the normal channel function. Synaptic terminals of mutant photoreceptors are disarranged and synaptic proteins as well as TMEM16A channels lose their characteristic localization. In parallel, calcium-activated chloride currents are impaired in rods, despite unaltered TMEM16A protein levels. Co-immunoprecipitation revealed the interaction between VGCC and TMEM16A channels in the retina. Heterologous expression of these channels in tsA-201 cells showed that TMEM16A associates with the CaV1.4 subunit, and the association persists upon expression of the mutant α2δ4 subunit. Collectively, our experiments show association between TMEM16A and the α1 subunit of VGCC. Close proximity of these channels allows optimal function of the photoreceptor synaptic terminal under physiological conditions, but also makes TMEM16A channels susceptible to changes occurring to calcium channels. PMID:26557056

Effects of funnel web spider toxin on Ca2+ currents in neurohypophysial terminals.

PubMed

Wang, G; Lemos, J R

1994-11-14

Funnel web spider toxin (FTX) is reportedly a specific blocker of P-type Ca2+ channels. The effects of FTX on the Ca2+ currents of isolated neurohypophysial nerve terminals of the rat were investigated using the 'whole-cell' patch-clamp technique. Both the transient and long-lasting Ca2+ current components were maximally elicited by depolarization from a holding potential equal to the normal terminal resting potential (-90 mV). Externally applied FTX inhibited the high-voltage-threshold, transient component of the Ca2+ current in a concentration-dependent manner, with a half-maximal inhibition at a dilution of approximately 1:10000. FTX also shifted the peak current of the I-V relationship by +10 mV. The long-lasting Ca2+ current component, which is sensitive to L-type Ca2+ channel blockers, was insensitive to FTX. The transient current, which is sensitive to omega-conotoxin GVIA, was completely blocked by FTX. These results suggest that there could be a novel, inactivating Ca2+ channel in the rat neurohypophysial terminals which is affected by both N-type and P-type Ca2+ channel blockers.

Cold cathode vacuum gauging system

DOEpatents

Denny, Edward C.

2004-03-09

A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

Offset-free rail-to-rail derandomizing peak detect-and-hold circuit

DOEpatents

DeGeronimo, Gianluigi; O'Connor, Paul; Kandasamy, Anand

2003-01-01

A peak detect-and-hold circuit eliminates errors introduced by conventional amplifiers, such as common-mode rejection and input voltage offset. The circuit includes an amplifier, three switches, a transistor, and a capacitor. During a detect-and-hold phase, a hold voltage at a non-inverting in put terminal of the amplifier tracks an input voltage signal and when a peak is reached, the transistor is switched off, thereby storing a peak voltage in the capacitor. During a readout phase, the circuit functions as a unity gain buffer, in which the voltage stored in the capacitor is provided as an output voltage. The circuit is able to sense signals rail-to-rail and can readily be modified to sense positive, negative, or peak-to-peak voltages. Derandomization may be achieved by using a plurality of peak detect-and-hold circuits electrically connected in parallel.

The scorpion toxin Bot IX is a potent member of the α-like family and has a unique N-terminal sequence extension.

PubMed

Martin-Eauclaire, Marie-France; Salvatierra, Juan; Bosmans, Frank; Bougis, Pierre E

2016-09-01

We report the detailed chemical, immunological and pharmacological characterization of the α-toxin Bot IX from the Moroccan scorpion Buthus occitanus tunetanus venom. Bot IX, which consists of 70 amino acids, is a highly atypical toxin. It carries a unique N-terminal sequence extension and is highly lethal in mice. Voltage clamp recordings on oocytes expressing rat Nav1.2 or insect BgNav1 reveal that, similar to other α-like toxins, Bot IX inhibits fast inactivation of both variants. Moreover, Bot IX belongs to the same structural/immunological group as the α-like toxin Bot I. Remarkably, radioiodinated Bot IX competes efficiently with the classical α-toxin AaH II from Androctonus australis, and displays one of the highest affinities for Nav channels. © 2016 Federation of European Biochemical Societies.

Atomically engineered epitaxial anatase TiO2 metal-semiconductor field-effect transistors

NASA Astrophysics Data System (ADS)

Kim, Brian S. Y.; Minohara, Makoto; Hikita, Yasuyuki; Bell, Christopher; Hwang, Harold Y.

2018-03-01

Anatase TiO2 is a promising material for a vast array of electronic, energy, and environmental applications, including photocatalysis, photovoltaics, and sensors. A key requirement for these applications is the ability to modulate its electrical properties without dominant dopant scattering and while maintaining high carrier mobility. Here, we demonstrate the room temperature field-effect modulation of the conducting epitaxial interface between anatase TiO2 and LaAlO3 (001), which arises for LaO-terminated LaAlO3, while the AlO2-terminated interface is insulating. This approach, together with the metal-semiconductor field-effect transistor geometry, naturally bypasses the gate/channel interface traps, resulting in a high field-effect mobility μ FE of 3.14 cm2 (V s)-1 approaching 98% of the corresponding Hall mobility μ Hall . Accordingly, the channel conductivity is modulated over 6 orders of magnitude over a gate voltage range of ˜4 V.

Pseudo-Hall Effect in Graphite on Paper Based Four Terminal Devices for Stress Sensing Applications

NASA Astrophysics Data System (ADS)

Qamar, Afzaal; Sarwar, Tuba; Dinh, Toan; Foisal, A. R. M.; Phan, Hoang-Phuong; Viet Dao, Dzung

2017-04-01

A cost effective and easy to fabricate stress sensor based on pseudo-Hall effect in Graphite on Paper (GOP) has been presented in this article. The four terminal devices were developed by pencil drawing with hand on to the paper substrate. The stress was applied to the paper containing four terminal devices with the input current applied at two terminals and the offset voltage observed at other two terminals called pseudo-Hall effect. The GOP stress sensor showed significant response to the applied stress which was smooth and linear. These results showed that the pseudo-Hall effect in GOP based four terminal devices can be used for cost effective, flexible and easy to make stress, strain or force sensors.

The Role of Neurotrophins in Neurotransmitter Release

PubMed Central

Tyler, William J.; Perrett, Stephen P.; Pozzo-Miller, Lucas D.

2009-01-01

The neurotrophins (NTs) have recently been shown to elicit pronounced effects on quantal neurotransmitter release at both central and peripheral nervous system synapses. Due to their activity-dependent release, as well as the subcellular localization of both protein and receptor, NTs are ideally suited to modify the strength of neuronal connections by “fine-tuning” synaptic activity through direct actions at presynaptic terminals. Here, using BDNF as a prototypical example, the authors provide an update of recent evidence demonstrating that NTs enhance quantal neurotransmitter release at synapses through presynaptic mechanisms. The authors further propose that a potential target for NT actions at presynaptic terminals is the mechanism by which terminals retrieve synaptic vesicles after exocytosis. Depending on the temporal demands placed on synapses during high-frequency synaptic transmission, synapses may use two alternative modes of synaptic vesicle retrieval, the conventional slow endosomal recycling or a faster rapid retrieval at the active zone, referred to as “kiss-and-run.” By modulating Ca2+ microdomains associated with voltage-gated Ca2+ channels at active zones, NTs may elicit a switch from the slow to the fast mode of endocytosis of vesicles at presynaptic terminals during high-frequency synaptic transmission, allowing more reliable information transfer and neuronal signaling in the central nervous system. PMID:12467374

The role of neurotrophins in neurotransmitter release.

PubMed

Tyler, William J; Perrett, Stephen P; Pozzo-Miller, Lucas D

2002-12-01

The neurotrophins (NTs) have recently been shown to elicit pronounced effects on quantal neurotransmitter release at both central and peripheral nervous system synapses. Due to their activity-dependent release, as well as the subcellular localization of both protein and receptor, NTs are ideally suited to modify the strength of neuronal connections by "fine-tuning" synaptic activity through direct actions at presynaptic terminals. Here, using BDNF as a prototypical example, the authors provide an update of recent evidence demonstrating that NTs enhance quantal neurotransmitter release at synapses through presynaptic mechanisms. The authors further propose that a potential target for NT actions at presynaptic terminals is the mechanism by which terminals retrieve synaptic vesicles after exocytosis. Depending on the temporal demands placed on synapses during high-frequency synaptic transmission, synapses may use two alternative modes of synaptic vesicle retrieval, the conventional slow endosomal recycling or a faster rapid retrieval at the active zone, referred to as "kiss-and-run." By modulating Ca2+ microdomains associated with voltage-gated Ca2+ channels at active zones, NTs may elicit a switch from the slow to the fast mode of endocytosis of vesicles at presynaptic terminals during high-frequency synaptic transmission, allowing more reliable information transfer and neuronal signaling in the central nervous system.

Electrostatic vibration energy harvester with 2.4-GHz Cockcroft-Walton rectenna start-up

NASA Astrophysics Data System (ADS)

Takhedmit, Hakim; Saddi, Zied; Karami, Armine; Basset, Philippe; Cirio, Laurent

2017-02-01

In this paper, we propose the design, fabrication and experiments of a macro-scale electrostatic vibration energy harvester (e-VEH), pre-charged wirelessly for the first time with a 2.4-GHz Cockcroft-Walton rectenna. The rectenna is designed and optimized to operate at low power densities and provide high voltage levels: 0.5 V at 0.76 μW/cm2 and 1 V at 1.53 μW/cm2. The e-VEH uses a Bennet doubler as a conditioning circuit. Experiments show a 23-V voltage across the transducer terminal, when the harvester is excited at 25 Hz by 1.5 g of external acceleration. An accumulated energy of 275 μJ and a maximum available power of 0.4 μW are achieved. xml:lang="fr"

Lightweight concentrator module with 30 percent AM0 efficient GaAs/GaSb tandem cells

NASA Technical Reports Server (NTRS)

Avery, J. E.; Fraas, L. M.; Sundaram, V. S.; Mansoori, N.; Yerkes, J. W.; Brinker, D. J.; Curtis, H. B.; O'Neill, M. J.

1990-01-01

A concept is presented for an aerospace concentrator module with lightweight domed lenses and 30 percent AM0 efficient GaAs/GaSb tandem solar cell circuits. The performance of transparent GaAs cells is reviewed. NASA's high-altitude jet flight calibration data for recent GaSb cells assembled with bulk GaAs filters are reported, along with subsequent Boeing and NASA measurements of GaSb I-V performance at various light levels and temperatures. The expected performance of a basic two-terminal tandem concentrator circuit with three-to-one voltage matching is discussed. All of the necessary components being developed to assemble complete flight test coupons are shown. Straightforward interconnect and assembly techniques yield voltage matched circuits with near-optimum performance over a wide temperature range.

Optimal III-nitride HEMTs: from materials and device design to compact model of the 2DEG charge density

NASA Astrophysics Data System (ADS)

Li, Kexin; Rakheja, Shaloo

2017-02-01

In this paper, we develop a physically motivated compact model of the charge-voltage (Q-V) characteristics in various III-nitride high-electron mobility transistors (HEMTs) operating under highly non-equilibrium transport conditions, i.e. high drain-source current. By solving the coupled Schrödinger-Poisson equation and incorporating the two-dimensional electrostatics in the channel, we obtain the charge at the top-of-the-barrier for various applied terminal voltages. The Q-V model accounts for cutting off of the negative momenta states from the drain terminal under high drain-source bias and when the transmission in the channel is quasi-ballistic. We specifically focus on AlGaN and AlInN as barrier materials and InGaN and GaN as the channel material in the heterostructure. The Q-V model is verified and calibrated against numerical results using the commercial TCAD simulator Sentaurus from Synopsys for a 20-nm channel length III-nitride HEMT. With 10 fitting parameters, most of which have a physical origin and can easily be obtained from numerical or experimental calibration, the compact Q-V model allows us to study the limits and opportunities of III-nitride technology. We also identify optimal material and geometrical parameters of the device that maximize the carrier concentration in the HEMT channel in order to achieve superior RF performance. Additionally, the compact charge model can be easily integrated in a hierarchical circuit simulator, such as Keysight ADS and CADENCE, to facilitate circuit design and optimization of various technology parameters.

Novel high-frequency energy-efficient pulsed-dc generator for capacitively coupled plasma discharge

NASA Astrophysics Data System (ADS)

Mamun, Md Abdullah Al; Furuta, Hiroshi; Hatta, Akimitsu

2018-03-01

The circuit design, assembly, and operating tests of a high-frequency and high-voltage (HV) pulsed dc generator (PDG) for capacitively coupled plasma (CCP) discharge inside a vacuum chamber are reported. For capacitive loads, it is challenging to obtain sharp rectangular pulses with fast rising and falling edges, requiring intense current for quick charging and discharging. The requirement of intense current generally limits the pulse operation frequency. In this study, we present a new type of PDG consisting of a pair of half-resonant converters and a constant current-controller circuit connected with HV solid-state power switches that can deliver almost rectangular high voltage pulses with fast rising and falling edges for CCP discharge. A prototype of the PDG is assembled to modulate from a high-voltage direct current (HVdc) input into a pulsed HVdc output, while following an input pulse signal and a set current level. The pulse rise time and fall time are less than 500 ns and 800 ns, respectively, and the minimum pulse width is 1 µs. The maximum voltage for a negative pulse is 1000 V, and the maximum repetition frequency is 500 kHz. During the pulse on time, the plasma discharge current is controlled steadily at the set value. The half-resonant converters in the PDG perform recovery of the remaining energy from the capacitive load at every termination of pulse discharge. The PDG performed with a high energy efficiency of 85% from the HVdc input to the pulsed dc output at a repetition rate of 1 kHz and with stable plasma operation in various discharge conditions. The results suggest that the developed PDG can be considered to be more efficient for plasma processing by CCP.

Novel high-frequency energy-efficient pulsed-dc generator for capacitively coupled plasma discharge.

PubMed

Mamun, Md Abdullah Al; Furuta, Hiroshi; Hatta, Akimitsu

2018-03-01

The circuit design, assembly, and operating tests of a high-frequency and high-voltage (HV) pulsed dc generator (PDG) for capacitively coupled plasma (CCP) discharge inside a vacuum chamber are reported. For capacitive loads, it is challenging to obtain sharp rectangular pulses with fast rising and falling edges, requiring intense current for quick charging and discharging. The requirement of intense current generally limits the pulse operation frequency. In this study, we present a new type of PDG consisting of a pair of half-resonant converters and a constant current-controller circuit connected with HV solid-state power switches that can deliver almost rectangular high voltage pulses with fast rising and falling edges for CCP discharge. A prototype of the PDG is assembled to modulate from a high-voltage direct current (HVdc) input into a pulsed HVdc output, while following an input pulse signal and a set current level. The pulse rise time and fall time are less than 500 ns and 800 ns, respectively, and the minimum pulse width is 1 µs. The maximum voltage for a negative pulse is 1000 V, and the maximum repetition frequency is 500 kHz. During the pulse on time, the plasma discharge current is controlled steadily at the set value. The half-resonant converters in the PDG perform recovery of the remaining energy from the capacitive load at every termination of pulse discharge. The PDG performed with a high energy efficiency of 85% from the HVdc input to the pulsed dc output at a repetition rate of 1 kHz and with stable plasma operation in various discharge conditions. The results suggest that the developed PDG can be considered to be more efficient for plasma processing by CCP.

Functional diversity of voltage-sensing phosphatases in two urodele amphibians.

PubMed

Mutua, Joshua; Jinno, Yuka; Sakata, Souhei; Okochi, Yoshifumi; Ueno, Shuichi; Tsutsui, Hidekazu; Kawai, Takafumi; Iwao, Yasuhiro; Okamura, Yasushi

2014-07-16

Voltage-sensing phosphatases (VSPs) share the molecular architecture of the voltage sensor domain (VSD) with voltage-gated ion channels and the phosphoinositide phosphatase region with the phosphatase and tensin homolog (PTEN), respectively. VSPs enzymatic activities are regulated by the motions of VSD upon depolarization. The physiological role of these proteins has remained elusive, and insights may be gained by investigating biological variations in different animal species. Urodele amphibians are vertebrates with potent activities of regeneration and also show diverse mechanisms of polyspermy prevention. We cloned cDNAs of VSPs from the testes of two urodeles; Hynobius nebulosus and Cynops pyrrhogaster, and compared their expression and voltage-dependent activation. Their molecular architecture is highly conserved in both Hynobius VSP (Hn-VSP) and Cynops VSP (Cp-VSP), including the positively-charged arginine residues in the S4 segment of the VSD and the enzymatic active site for substrate binding, yet the C-terminal C2 domain of Hn-VSP is significantly shorter than that of Cp-VSP and other VSP orthologs. RT-PCR analysis showed that gene expression pattern was distinct between two VSPs. The voltage sensor motions and voltage-dependent phosphatase activities were investigated electrophysiologically by expression in Xenopus oocytes. Both VSPs showed "sensing" currents, indicating that their voltage sensor domains are functional. The phosphatase activity of Cp-VSP was found to be voltage dependent, as shown by its ability to regulate the conductance of coexpressed GIRK2 channels, but Hn-VSP lacked such phosphatase activity due to the truncation of its C2 domain. © 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

PRECISION TIME-DELAY CIRCUIT

DOEpatents

Creveling, R.

1959-03-17

A tine-delay circuit which produces a delay time in d. The circuit a capacitor, an te back resistance, connected serially with the anode of the diode going to ground. At the start of the time delay a negative stepfunction is applied to the series circuit and initiates a half-cycle transient oscillatory voltage terminated by a transient oscillatory voltage of substantially higher frequency. The output of the delay circuit is taken at the junction of the inductor and diode where a sudden voltage rise appears after the initiation of the higher frequency transient oscillations.

Self-discharge analysis and characterization of supercapacitors for environmentally powered wireless sensor network applications

NASA Astrophysics Data System (ADS)

Yang, Hengzhao; Zhang, Ying

2011-10-01

A new approach is presented to characterize the variable leakage resistance, a parameter in the variable leakage resistance model we developed to model supercapacitors used in environmentally powered wireless sensor network applications. Based on an analysis of the supercapacitor terminal behavior during the self-discharge, the variable leakage resistance is modeled as a function of the supercapacitor terminal voltage instead of the self-discharge time, which is more practical for an environmentally powered wireless sensor node. The new characterization approach is implemented and validated using MATLAB Simulink with a 10 F supercapacitor as an example. In addition, effects of initial voltages and temperatures on the supercapacitor self-discharge rate and the variable leakage resistance value are explored.

Charge recombination in organic photovoltaic devices with high open-circuit voltages.

PubMed

Westenhoff, Sebastian; Howard, Ian A; Hodgkiss, Justin M; Kirov, Kiril R; Bronstein, Hugo A; Williams, Charlotte K; Greenham, Neil C; Friend, Richard H

2008-10-15

A detailed charge recombination mechanism is presented for organic photovoltaic devices with a high open-circuit voltage. In a binary blend comprised of polyfluorene copolymers, the performance-limiting process is found to be the efficient recombination of tightly bound charge pairs into neutral triplet excitons. We arrive at this conclusion using optical transient absorption (TA) spectroscopy with visible and IR probes and over seven decades of time resolution. By resolving the polarization of the TA signal, we track the movement of polaronic states generated at the heterojunction not only in time but also in space. It is found that the photogenerated charge pairs are remarkably immobile at the heterojunction during their lifetime. The charge pairs are shown to be subject to efficient intersystem crossing and terminally recombine into F8BT triplet excitons within approximately 40 ns. Long-range charge separation competes rather unfavorably with intersystem crossing--75% of all charge pairs decay into triplet excitons. Triplet exciton states are thermodynamically accessible in polymer solar cells with high open circuit voltage, and we therefore suggest this loss mechanism to be general. We discuss guidelines for the design of the next generation of organic photovoltaic materials where separating the metastable interfacial charge pairs within approximately 40 ns is paramount.

Jitter compensation circuit

DOEpatents

Sullivan, James S.; Ball, Don G.

1997-01-01

The instantaneous V.sub.co signal on a charging capacitor is sampled and the charge voltage on capacitor C.sub.o is captured just prior to its discharge into the first stage of magnetic modulator. The captured signal is applied to an averaging circuit with a long time constant and to the positive input terminal of a differential amplifier. The averaged V.sub. co signal is split between a gain stage (G=0.975) and a feedback stage that determines the slope of the voltage ramp applied to the high speed comparator. The 97.5% portion of the averaged V.sub.co signal is applied to the negative input of a differential amplifier gain stage (G=10). The differential amplifier produces an error signal by subtracting 97.5% of the averaged V.sub.co signal from the instantaneous value of sampled V.sub.co signal and multiplying the difference by ten. The resulting error signal is applied to the positive input of a high speed comparator. The error signal is then compared to a voltage ramp that is proportional to the averaged V.sub.co values squared divided by the total volt-second product of the magnetic compression circuit.

Jitter compensation circuit

DOEpatents

Sullivan, J.S.; Ball, D.G.

1997-09-09

The instantaneous V{sub co} signal on a charging capacitor is sampled and the charge voltage on capacitor C{sub o} is captured just prior to its discharge into the first stage of magnetic modulator. The captured signal is applied to an averaging circuit with a long time constant and to the positive input terminal of a differential amplifier. The averaged V{sub co} signal is split between a gain stage (G = 0.975) and a feedback stage that determines the slope of the voltage ramp applied to the high speed comparator. The 97.5% portion of the averaged V{sub co} signal is applied to the negative input of a differential amplifier gain stage (G = 10). The differential amplifier produces an error signal by subtracting 97.5% of the averaged V{sub co} signal from the instantaneous value of sampled V{sub co} signal and multiplying the difference by ten. The resulting error signal is applied to the positive input of a high speed comparator. The error signal is then compared to a voltage ramp that is proportional to the averaged V{sub co} values squared divided by the total volt-second product of the magnetic compression circuit. 11 figs.

Predictions of Microstreamer Properties in Dielectric Barrier Discharges

NASA Astrophysics Data System (ADS)

Xu, Xudong; Kushner, Mark J.

1997-10-01

Dielectric Barrier Discharges (DBD) are being investigated for plasma remediation of toxic gases. The microstreamers in DBD's (10s - 100s μm's diameter) are terminated by dielectric charging which removes voltage from the gap. The microstreamers grow by radial diffusion into regions of high electric field and subsequent avalanche. 1-d and 2-d plasma hydrodynamics models have been developed to investigate these processes in DBDs sustained in air, nonattaching gases (Ar, N_2) and highly attaching gas mixtures (10s to 100s ppm of CCl_4). We found that microstreamers continue to radially expand as long as there is sufficient applied voltage in the absence of dielectric charging in advance of the core of the microstreamer. This observation implies that there is a finite surface conductivity which allows radial flow of current and subsequent charging of the dielectric. Predictions for microstreamer radii using this process agree well with experiments.(J. Coogan, Trans. Plasma Sci. 24, 91 (1996)) We also found that in electronegative gases, voltage collapes in the core of the streamer results in cooling and rapid attachment of electrons, creating a core which is largely converted to a negative ion-positive ion plasma, surrounded by an avalanching shell of hot electrons.

Durability-enhanced two-dimensional hole gas of C-H diamond surface for complementary power inverter applications

PubMed Central

Kawarada, Hiroshi; Yamada, Tetsuya; Xu, Dechen; Tsuboi, Hidetoshi; Kitabayashi, Yuya; Matsumura, Daisuke; Shibata, Masanobu; Kudo, Takuya; Inaba, Masafumi; Hiraiwa, Atsushi

2017-01-01

Complementary power field effect transistors (FETs) based on wide bandgap materials not only provide high-voltage switching capability with the reduction of on-resistance and switching losses, but also enable a smart inverter system by the dramatic simplification of external circuits. However, p-channel power FETs with equivalent performance to those of n-channel FETs are not obtained in any wide bandgap material other than diamond. Here we show that a breakdown voltage of more than 1600 V has been obtained in a diamond metal-oxide-semiconductor (MOS) FET with a p-channel based on a two-dimensional hole gas (2DHG). Atomic layer deposited (ALD) Al2O3 induces the 2DHG ubiquitously on a hydrogen-terminated (C-H) diamond surface and also acts as both gate insulator and passivation layer. The high voltage performance is equivalent to that of state-of-the-art SiC planar n-channel FETs and AlGaN/GaN FETs. The drain current density in the on-state is also comparable to that of these two FETs with similar device size and VB. PMID:28218234

Durability-enhanced two-dimensional hole gas of C-H diamond surface for complementary power inverter applications.

PubMed

Kawarada, Hiroshi; Yamada, Tetsuya; Xu, Dechen; Tsuboi, Hidetoshi; Kitabayashi, Yuya; Matsumura, Daisuke; Shibata, Masanobu; Kudo, Takuya; Inaba, Masafumi; Hiraiwa, Atsushi

2017-02-20

Complementary power field effect transistors (FETs) based on wide bandgap materials not only provide high-voltage switching capability with the reduction of on-resistance and switching losses, but also enable a smart inverter system by the dramatic simplification of external circuits. However, p-channel power FETs with equivalent performance to those of n-channel FETs are not obtained in any wide bandgap material other than diamond. Here we show that a breakdown voltage of more than 1600 V has been obtained in a diamond metal-oxide-semiconductor (MOS) FET with a p-channel based on a two-dimensional hole gas (2DHG). Atomic layer deposited (ALD) Al 2 O 3 induces the 2DHG ubiquitously on a hydrogen-terminated (C-H) diamond surface and also acts as both gate insulator and passivation layer. The high voltage performance is equivalent to that of state-of-the-art SiC planar n-channel FETs and AlGaN/GaN FETs. The drain current density in the on-state is also comparable to that of these two FETs with similar device size and V B .

Native pyroglutamation of huwentoxin-IV: a post-translational modification that increases the trapping ability to the sodium channel.

PubMed

Rong, Mingqiang; Duan, Zhigui; Chen, Juliang; Li, Jianglin; Xiao, Yuchen; Liang, Songping

2013-01-01

Huwentoxin-IV (HWTX-IV), a tetrodotoxin-sensitive (TTX-s) sodium channel antagonist, is found in the venom of the Chinese spider Ornithoctonus huwena. A naturally modified HWTX-IV (mHWTX-IV), having a molecular mass 18 Da lower than HWTX-IV, has also been isolated from the venom of the same spider. By a combination of enzymatic fragmentation and MS/MS de novo sequencing, mHWTX-IV has been shown to have the same amino acid sequence as that of HWTX-IV, except that the N-terminal glutamic acid replaced by pyroglutamic acid. mHWTX-IV inhibited tetrodotoxin-sensitive voltage-gated sodium channels of dorsal root ganglion neurons with an IC50 nearly equal to native HWTX-IV. mHWTX-IV showed the same activation and inactivation kinetics seen for native HWTX-IV. In contrast with HWTX-IV, which dissociates at moderate voltage depolarization voltages (+50 mV, 180000 ms), mHWTX-IV inhibition of TTX-sensitive sodium channels is not reversed by strong depolarization voltages (+200 mV, 500 ms). Recovery of Nav1.7current was voltage-dependent and was induced by extreme depolarization in the presence of HWTX-IV, but no obvious current was elicited after application of mHWTX-IV. Our data indicate that the N-terminal modification of HWTX-IV gives the peptide toxin a greater ability to trap the voltage sensor in the sodium channel. Loss of a negative charge, caused by cyclization at the N-terminus, is a possible reason why the modified toxin binds much stronger. To our knowledge, this is the first report of a pyroglutamic acid residue in a spider toxin; this modification seems to increase the trapping ability of the voltage sensor in the sodium channel.

Native Pyroglutamation of Huwentoxin-IV: A Post-Translational Modification that Increases the Trapping Ability to the Sodium Channel

PubMed Central

Rong, Mingqiang; Duan, Zhigui; Chen, Juliang; Li, Jianglin; Xiao, Yuchen; Liang, Songping

2013-01-01

Huwentoxin-IV (HWTX-IV), a tetrodotoxin-sensitive (TTX-s) sodium channel antagonist, is found in the venom of the Chinese spider Ornithoctonus huwena. A naturally modified HWTX-IV (mHWTX-IV), having a molecular mass 18 Da lower than HWTX-IV, has also been isolated from the venom of the same spider. By a combination of enzymatic fragmentation and MS/MS de novo sequencing, mHWTX-IV has been shown to have the same amino acid sequence as that of HWTX-IV, except that the N-terminal glutamic acid replaced by pyroglutamic acid. mHWTX-IV inhibited tetrodotoxin-sensitive voltage-gated sodium channels of dorsal root ganglion neurons with an IC50 nearly equal to native HWTX-IV. mHWTX-IV showed the same activation and inactivation kinetics seen for native HWTX-IV. In contrast with HWTX-IV, which dissociates at moderate voltage depolarization voltages (+50 mV, 180000 ms), mHWTX-IV inhibition of TTX-sensitive sodium channels is not reversed by strong depolarization voltages (+200 mV, 500 ms). Recovery of Nav1.7current was voltage-dependent and was induced by extreme depolarization in the presence of HWTX-IV, but no obvious current was elicited after application of mHWTX-IV. Our data indicate that the N-terminal modification of HWTX-IV gives the peptide toxin a greater ability to trap the voltage sensor in the sodium channel. Loss of a negative charge, caused by cyclization at the N-terminus, is a possible reason why the modified toxin binds much stronger. To our knowledge, this is the first report of a pyroglutamic acid residue in a spider toxin; this modification seems to increase the trapping ability of the voltage sensor in the sodium channel. PMID:23826086

Control design for a wind turbine-generator using output feedback

NASA Technical Reports Server (NTRS)

Javid, S. H.; Murdoch, A.; Winkelman, J. R.

1981-01-01

The modeling and approach to control design for a large horizontal axis wind turbine (WT) generator are presented. The control design is based on a suboptimal output regulator which allows coordinated control of WT blade pitch angle and field voltage for the purposes of regulating electrical power and terminal voltage. Results of detailed non-linear simulation tests of this controller are shown.

Control design for a wind turbine-generator using output feedback

NASA Astrophysics Data System (ADS)

Javid, S. H.; Murdoch, A.; Winkelman, J. R.

The modeling and approach to control design for a large horizontal axis wind turbine (WT) generator are presented. The control design is based on a suboptimal output regulator which allows coordinated control of WT blade pitch angle and field voltage for the purposes of regulating electrical power and terminal voltage. Results of detailed non-linear simulation tests of this controller are shown.

Post-Test Inspection of NASA's Evolutionary Xenon Thruster Long-Duration Test Hardware: Discharge Chamber

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Soulas, George C.

2016-01-01

NASAs Evolutionary Xenon Thruster (NEXT) Long-Duration Test (LDT) is part of the comprehensive service life assessment of the NEXT thruster. The test was voluntarily terminated in April 2014 after accumulating 51,184 hours of high voltage operation, processing 918 kg of xenon, and delivering 35.5 MN-s of total impulse. This presentation covers the post-test inspection of the thruster hardware, in particular of the discharge chamber and other miscellaneous components such as propellant isolators and electrical cabling.

Project Echo: Antenna Steering System

NASA Technical Reports Server (NTRS)

Klahn, R.; Norton, J. A.; Githens, J. A.

1961-01-01

The Project Echo communications experiment employed large, steerable,transmitting and receiving antennas at the ground terminals. It was necessary that these highly directional antennas be continuously and accurately pointed at the passing satellite. This paper describes a new type of special purpose data converter for directing narrow-beam communication antennas on the basis of predicted information. The system is capable of converting digital input data into real-time analog voltage commands with a dynamic accuracy of +/- 0.05 degree, which meets the requirements of the present antennas.

Monolithic FET structures for high-power control component applications

NASA Astrophysics Data System (ADS)

Shifrin, Mitchell B.; Katzin, Peter J.; Ayasli, Yalcin

1989-12-01

A monolithic FET switch is described that can be integrated with other monolithic functions or used as a discrete component in a microwave integrated circuit structure. This device increases the power-handling capability of the conventional single FET switch by an order of magnitude. It does this by overcoming the breakdown voltage limitation of the FET device. The design, fabrication, and performance of two high-power control components using these circuits are described as examples of the implementation of this technology. They are an L-band terminated single-pole, single-throw (SPST) switch and an L-band limiter).

An advanced communications synthesizer

NASA Astrophysics Data System (ADS)

Scherer, Ernst F.

1994-02-01

With the proliferation of smaller and lower cost EHF terminals, the fast-hopping microwave synthesizer subsystem is rapidly becoming the limiting factor for further size and cost reduction. A new approach, based on a high-speed direct digital synthesizer (DDS) and a very fast voltage controlled oscillator (VCO) tracking loop, has yielded a highly integrable design with true low-cost potential. A frequency range of 1 to 20 GHz can be covered by a simple substitution of the VCO module. This advanced synthesizer realization promises a generic solution to a large class of synthesizer requirements, greatly facilitating standardization and promoting modular system concepts.

10 CFR Appendix D to Subpart B of... - Uniform Test Method for Measuring the Energy Consumption of Clothes Dryers

Code of Federal Regulations, 2010 CFR

2010-01-01

... clothes drying cycle when the added gas or electric heat is terminated and the clothes continue to tumble... termination control” means a dryer control system with a sensor which monitors either the dryer load... highest voltage specified by the manufacturer. 2.3.2Gas supply. 2.3.2.1Natural gas. Maintains the gas...

Synaptic behaviors of thin-film transistor with a Pt/HfO x /n-type indium-gallium-zinc oxide gate stack.

PubMed

Yang, Paul; Park, Daehoon; Beom, Keonwon; Kim, Hyung Jun; Kang, Chi Jung; Yoon, Tae-Sik

2018-07-20

We report a variety of synaptic behaviors in a thin-film transistor (TFT) with a metal-oxide-semiconductor gate stack that has a Pt/HfO x /n-type indium-gallium-zinc oxide (n-IGZO) structure. The three-terminal synaptic TFT exhibits a tunable synaptic weight with a drain current modulation upon repeated application of gate and drain voltages. The synaptic weight modulation is analog, voltage-polarity dependent reversible, and strong with a dynamic range of multiple orders of magnitude (>10 4 ). This modulation process emulates biological synaptic potentiation, depression, excitatory-postsynaptic current, paired-pulse facilitation, and short-term to long-term memory transition behaviors as a result of repeated pulsing with respect to the pulse amplitude, width, repetition number, and the interval between pulses. These synaptic behaviors are interpreted based on the changes in the capacitance of the Pt/HfO x /n-IGZO gate stack, the channel mobility, and the threshold voltage that result from the redistribution of oxygen ions by the applied gate voltage. These results demonstrate the potential of this structure for three-terminal synaptic transistor using the gate stack composed of the HfO x gate insulator and the IGZO channel layer.

Synaptic behaviors of thin-film transistor with a Pt/HfO x /n-type indium–gallium–zinc oxide gate stack

NASA Astrophysics Data System (ADS)

Yang, Paul; Park, Daehoon; Beom, Keonwon; Kim, Hyung Jun; Kang, Chi Jung; Yoon, Tae-Sik

2018-07-01

We report a variety of synaptic behaviors in a thin-film transistor (TFT) with a metal-oxide-semiconductor gate stack that has a Pt/HfO x /n-type indium–gallium–zinc oxide (n-IGZO) structure. The three-terminal synaptic TFT exhibits a tunable synaptic weight with a drain current modulation upon repeated application of gate and drain voltages. The synaptic weight modulation is analog, voltage-polarity dependent reversible, and strong with a dynamic range of multiple orders of magnitude (>104). This modulation process emulates biological synaptic potentiation, depression, excitatory-postsynaptic current, paired-pulse facilitation, and short-term to long-term memory transition behaviors as a result of repeated pulsing with respect to the pulse amplitude, width, repetition number, and the interval between pulses. These synaptic behaviors are interpreted based on the changes in the capacitance of the Pt/HfO x /n-IGZO gate stack, the channel mobility, and the threshold voltage that result from the redistribution of oxygen ions by the applied gate voltage. These results demonstrate the potential of this structure for three-terminal synaptic transistor using the gate stack composed of the HfO x gate insulator and the IGZO channel layer.

System and method for determining stator winding resistance in an AC motor

DOEpatents

Lu, Bin [Kenosha, WI; Habetler, Thomas G [Snellville, GA; Zhang, Pinjia [Atlanta, GA; Theisen, Peter J [West Bend, WI

2011-05-31

A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

Low-Temperature Carrier Transport in Ionic-Liquid-Gated Hydrogen-Terminated Silicon

NASA Astrophysics Data System (ADS)

Sasama, Yosuke; Yamaguchi, Takahide; Tanaka, Masashi; Takeya, Hiroyuki; Takano, Yoshihiko

2017-11-01

We fabricated ionic-liquid-gated field-effect transistors on the hydrogen-terminated (111)-oriented surface of undoped silicon. Ion implantation underneath electrodes leads to good ohmic contacts, which persist at low temperatures down to 1.4 K. The sheet resistance of the channel decreases by more than five orders of magnitude as the gate voltage is changed from 0 to -1.6 V at 220 K. This is caused by the accumulation of hole carriers. The sheet resistance shows thermally activated behavior at temperatures below 10 K, which is attributed to hopping transport of the carriers. The activation energy decreases towards zero with increasing carrier density, suggesting the approach to an insulator-metal transition. We also report the variation of device characteristics induced by repeated sweeps of the gate voltage.

Large discharge-volume, silent discharge spark plug

DOEpatents

Kang, Michael

1995-01-01

A large discharge-volume spark plug for providing self-limiting microdischarges. The apparatus includes a generally spark plug-shaped arrangement of a pair of electrodes, where either of the two coaxial electrodes is substantially shielded by a dielectric barrier from a direct discharge from the other electrode, the unshielded electrode and the dielectric barrier forming an annular volume in which self-terminating microdischarges occur when alternating high voltage is applied to the center electrode. The large area over which the discharges occur, and the large number of possible discharges within the period of an engine cycle, make the present silent discharge plasma spark plug suitable for use as an ignition source for engines. In the situation, where a single discharge is effective in causing ignition of the combustible gases, a conventional single-polarity, single-pulse, spark plug voltage supply may be used.

Characterization of 109 Ah Ni-MH batteries charging with hydrogen sensing termination

NASA Astrophysics Data System (ADS)

Viera, J. C.; González, M.; Liaw, B. Y.; Ferrero, F. J.; Álvarez, J. C.; Campo, J. C.; Blanco, C.

The use of Ni-MH batteries for traction applications in electric and hybrid vehicles is increasingly attractive and reliable. Besides the energy and power handling, and the cost issues, high tolerance to abuse is an important aspect of the Ni-MH technology. Thus, the ability to reduce charging time and to absorb regenerative breaking is highly desirable in these traction applications. This requires an accurate control of the charge termination. To facilitate an easy and reliable charging control and to avoid battery premature failure or ageing it is very important to know the behavior of the battery under a range of charging conditions. In this paper, we described the performance of high capacity commercial Ni-MH traction batteries (12 V, 109 Ah modules) when subjected to different charging rates (0.1, 0.2, 0.5, and 1.0 C) from 100% depth of discharge (DOD). Changes in battery voltage and temperature during charging were monitored, with a particular emphasis on the detection of the presence of hydrogen near the battery. This unique hydrogen detection outside the battery was used as the method for the end-of-charge termination to prevent overcharging of the battery. Relevant parameters, such as charge acceptance, energy efficiency, and charging time, were analyzed for comparison.

Reactive power and voltage control strategy based on dynamic and adaptive segment for DG inverter

NASA Astrophysics Data System (ADS)

Zhai, Jianwei; Lin, Xiaoming; Zhang, Yongjun

2018-03-01

The inverter of distributed generation (DG) can support reactive power to help solve the problem of out-of-limit voltage in active distribution network (ADN). Therefore, a reactive voltage control strategy based on dynamic and adaptive segment for DG inverter is put forward to actively control voltage in this paper. The proposed strategy adjusts the segmented voltage threshold of Q(U) droop curve dynamically and adaptively according to the voltage of grid-connected point and the power direction of adjacent downstream line. And then the reactive power reference of DG inverter can be got through modified Q(U) control strategy. The reactive power of inverter is controlled to trace the reference value. The proposed control strategy can not only control the local voltage of grid-connected point but also help to maintain voltage within qualified range considering the terminal voltage of distribution feeder and the reactive support for adjacent downstream DG. The scheme using the proposed strategy is compared with the scheme without the reactive support of DG inverter and the scheme using the Q(U) control strategy with constant segmented voltage threshold. The simulation results suggest that the proposed method has a significant improvement on solving the problem of out-of-limit voltage, restraining voltage variation and improving voltage quality.

Micromolar-Affinity Benzodiazepine Receptors Regulate Voltage-Sensitive Calcium Channels in Nerve Terminal Preparations

NASA Astrophysics Data System (ADS)

Taft, William C.; Delorenzo, Robert J.

1984-05-01

Benzodiazepines in micromolar concentrations significantly inhibit depolarization-sensitive Ca2+ uptake in intact nerve-terminal preparations. Benzodiazepine inhibition of Ca2+ uptake is concentration dependent and stereospecific. Micromolar-affinity benzodiazepine receptors have been identified and characterized in brain membrane and shown to be distinct from nanomolar-affinity benzodiazepine receptors. Evidence is presented that micromolar, and not nanomolar, benzodiazepine binding sites mediate benzodiazepine inhibition of Ca2+ uptake. Irreversible binding to micromolar benzodiazepine binding sites also irreversibly blocked depolarization-dependent Ca2+ uptake in synaptosomes, indicating that these compounds may represent a useful marker for identifying the molecular components of Ca2+ channels in brain. Characterization of benzodiazepine inhibition of Ca2+ uptake demonstrates that these drugs function as Ca2+ channel antagonists, because benzodiazepines effectively blocked voltage-sensitive Ca2+ uptake inhibited by Mn2+, Co2+, verapamil, nitrendipine, and nimodipine. These results indicate that micromolar benzodiazepine binding sites regulate voltage-sensitive Ca2+ channels in brain membrane and suggest that some of the neuronal stabilizing effects of micromolar benzodiazepine receptors may be mediated by the regulation of Ca2+ conductance.

Micromolar-affinity benzodiazepine receptors regulate voltage-sensitive calcium channels in nerve terminal preparations.

PubMed Central

Taft, W C; DeLorenzo, R J

1984-01-01

Benzodiazepines in micromolar concentrations significantly inhibit depolarization-sensitive Ca2+ uptake in intact nerve-terminal preparations. Benzodiazepine inhibition of Ca2+ uptake is concentration dependent and stereospecific. Micromolar-affinity benzodiazepine receptors have been identified and characterized in brain membrane and shown to be distinct from nanomolar-affinity benzodiazepine receptors. Evidence is presented that micromolar, and not nanomolar, benzodiazepine binding sites mediate benzodiazepine inhibition of Ca2+ uptake. Irreversible binding to micromolar benzodiazepine binding sites also irreversibly blocked depolarization-dependent Ca2+ uptake in synaptosomes, indicating that these compounds may represent a useful marker for identifying the molecular components of Ca2+ channels in brain. Characterization of benzodiazepine inhibition of Ca2+ uptake demonstrates that these drugs function as Ca2+ channel antagonists, because benzodiazepines effectively blocked voltage-sensitive Ca2+ uptake inhibited by Mn2+, Co2+, verapamil, nitrendipine, and nimodipine. These results indicate that micromolar benzodiazepine binding sites regulate voltage-sensitive Ca2+ channels in brain membrane and suggest that some of the neuronal stabilizing effects of micromolar benzodiazepine receptors may be mediated by the regulation of Ca2+ conductance. PMID:6328498

Crystal Structure of the Ternary Complex of a NaV C-Terminal Domain, a Fibroblast Growth Factor Homologous Factor, and Calmodulin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Chaojian; Chung, Ben C.; Yan, Haidun

2012-11-13

Voltage-gated Na{sup +} (Na{sub V}) channels initiate neuronal action potentials. Na{sub V} channels are composed of a transmembrane domain responsible for voltage-dependent Na{sup +} conduction and a cytosolic C-terminal domain (CTD) that regulates channel function through interactions with many auxiliary proteins, including fibroblast growth factor homologous factors (FHFs) and calmodulin (CaM). Most ion channel structural studies have focused on mechanisms of permeation and voltage-dependent gating but less is known about how intracellular domains modulate channel function. Here we report the crystal structure of the ternary complex of a human NaV CTD, an FHF, and Ca{sup 2+}-free CaM at 2.2 {angstrom}.more » Combined with functional experiments based on structural insights, we present a platform for understanding the roles of these auxiliary proteins in NaV channel regulation and the molecular basis of mutations that lead to neuronal and cardiac diseases. Furthermore, we identify a critical interaction that contributes to the specificity of individual NaV CTD isoforms for distinctive FHFs.« less

Three-Level 48-Pulse STATCOM with Pulse Width Modulation

NASA Astrophysics Data System (ADS)

Singh, Bhim; Srinivas, Kadagala Venkata

2016-03-01

In this paper, a new control strategy of a three-level 48-pulse static synchronous compensator (STATCOM) is proposed with a constant dc link voltage and pulse width modulation at fundamental frequency switching. The proposed STATCOM is realized using eight units of three-level voltage source converters (VSCs) to form a three-level 48-pulse STATCOM. The conduction angle of each three-level VSC is modulated to control the ac converter output voltage, which controls the reactive power of the STATCOM. A fuzzy logic controller is used to control the STATCOM. The dynamic performance of the STATCOM is studied for the control of the reference reactive power, the reference terminal voltage and under the switching of inductive and capacitive loads.

Fabrication of high-performance InGaZnOx thin film transistors based on control of oxidation using a low-temperature plasma

NASA Astrophysics Data System (ADS)

Takenaka, Kosuke; Endo, Masashi; Uchida, Giichiro; Setsuhara, Yuichi

2018-04-01

This work demonstrated the low-temperature control of the oxidation of Amorphous InGaZnOx (a-IGZO) films using inductively coupled plasma as a means of precisely tuning the properties of thin film transistors (TFTs) and as an alternative to post-deposition annealing at high temperatures. The effects of the plasma treatment of the as-deposited a-IGZO films were investigated by assessing the electrical properties of TFTs incorporating these films. A TFT fabricated using an a-IGZO film exposed to an Ar-H2-O2 plasma at substrate temperatures as low as 300 °C exhibited the best performance, with a field effect mobility as high as 42.2 cm2 V-1 s-1, a subthreshold gate voltage swing of 1.2 V decade-1, and a threshold voltage of 2.8 V. The improved transfer characteristics of TFTs fabricated with a-IGZO thin films treated using an Ar-H2-O2 plasma are attributed to the termination of oxygen vacancies around Ga and Zn atoms by OH radicals in the gas phase.

Interarea Oscillation Damping Control Using High Voltage DC Transmission: a Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elizondo, Marcelo Anibal; Fan, Rui; Kirkham, Harold

High-voltage, direct current (HVDC) transmission lines are increasingly being installed in power systems around the world, and this trend is expected to continue with advancements in power electronics technology. These advancements are also bringing multi-terminal direct current (MTDC) systems closer to practical application. In addition, the continued deployment of phasor measurement units (PMUs) makes dynamic information about a large power system readily available for highly controllable components, such as HVDC lines. All these trends have increased the appeal of modulating HVDC lines and MTDC systems to provide grid services in addition to bulk power transfers. This paper provides a literaturemore » survey of HVDC and MTDC damping controllers for interarea oscillations in large interconnected power systems. The literature shows a progression from theoretical research to practical applications. Finally, there are already practical implementations of HVDC modulation for lines in point-to-point configuration, although the modulation of MTDC systems is still in the research stage. As a conclusion, this paper identifies and summarizes open questions that remain to be tackled by researchers and engineers.« less

Interarea Oscillation Damping Control Using High Voltage DC Transmission: a Survey

DOE PAGES

Elizondo, Marcelo Anibal; Fan, Rui; Kirkham, Harold; ...

2018-05-02

High-voltage, direct current (HVDC) transmission lines are increasingly being installed in power systems around the world, and this trend is expected to continue with advancements in power electronics technology. These advancements are also bringing multi-terminal direct current (MTDC) systems closer to practical application. In addition, the continued deployment of phasor measurement units (PMUs) makes dynamic information about a large power system readily available for highly controllable components, such as HVDC lines. All these trends have increased the appeal of modulating HVDC lines and MTDC systems to provide grid services in addition to bulk power transfers. This paper provides a literaturemore » survey of HVDC and MTDC damping controllers for interarea oscillations in large interconnected power systems. The literature shows a progression from theoretical research to practical applications. Finally, there are already practical implementations of HVDC modulation for lines in point-to-point configuration, although the modulation of MTDC systems is still in the research stage. As a conclusion, this paper identifies and summarizes open questions that remain to be tackled by researchers and engineers.« less

High performance bias-selectable three-color Short-wave/Mid-wave/Long-wave Infrared Photodetectors based on Type-II InAs/GaSb/AlSb superlattices

PubMed Central

Hoang, Anh Minh; Dehzangi, Arash; Adhikary, Sourav; Razeghi, Manijeh

2016-01-01

We propose a new approach in device architecture to realize bias-selectable three-color shortwave-midwave-longwave infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices. The effect of conduction band off-set and different doping levels between two absorption layers are employed to control the turn-on voltage for individual channels. The optimization of these parameters leads to a successful separation of operation regimes; we demonstrate experimentally three-color photodiodes without using additional terminal contacts. As the applied bias voltage varies, the photodiodes exhibit sequentially the behavior of three different colors, corresponding to the bandgap of three absorbers. Well defined cut-offs and high quantum efficiency in each channel are achieved. Such all-in-one devices also provide the versatility of working as single or dual-band photodetectors at high operating temperature. With this design, by retaining the simplicity in device fabrication, this demonstration opens the prospect for three-color infrared imaging. PMID:27051979

Application of HFCT and UHF Sensors in On-Line Partial Discharge Measurements for Insulation Diagnosis of High Voltage Equipment

PubMed Central

Álvarez, Fernando; Garnacho, Fernando; Ortego, Javier; Sánchez-Urán, Miguel Ángel

2015-01-01

Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment. PMID:25815452

Current Modulation of a Heterojunction Structure by an Ultra-Thin Graphene Base Electrode.

PubMed

Alvarado Chavarin, Carlos; Strobel, Carsten; Kitzmann, Julia; Di Bartolomeo, Antonio; Lukosius, Mindaugas; Albert, Matthias; Bartha, Johann Wolfgang; Wenger, Christian

2018-02-27

Graphene has been proposed as the current controlling element of vertical transport in heterojunction transistors, as it could potentially achieve high operation frequencies due to its metallic character and 2D nature. Simulations of graphene acting as a thermionic barrier between the transport of two semiconductor layers have shown cut-off frequencies larger than 1 THz. Furthermore, the use of n-doped amorphous silicon, (n)-a-Si:H, as the semiconductor for this approach could enable flexible electronics with high cutoff frequencies. In this work, we fabricated a vertical structure on a rigid substrate where graphene is embedded between two differently doped (n)-a-Si:H layers deposited by very high frequency (140 MHz) plasma-enhanced chemical vapor deposition. The operation of this heterojunction structure is investigated by the two diode-like interfaces by means of temperature dependent current-voltage characterization, followed by the electrical characterization in a three-terminal configuration. We demonstrate that the vertical current between the (n)-a-Si:H layers is successfully controlled by the ultra-thin graphene base voltage. While current saturation is yet to be achieved, a transconductance of ~230 μ S was obtained, demonstrating a moderate modulation of the collector-emitter current by the ultra-thin graphene base voltage. These results show promising progress towards the application of graphene base heterojunction transistors.

Memristor-based programmable logic array (PLA) and analysis as Memristive networks.

PubMed

Lee, Kwan-Hee; Lee, Sang-Jin; Kim, Seok-Man; Cho, Kyoungrok

2013-05-01

A Memristor theorized by Chua in 1971 has the potential to dramatically influence the way electronic circuits are designed. It is a two terminal device whose resistance state is based on the history of charge flow brought about as the result of the voltage being applied across its terminals and hence can be thought of as a special case of a reconfigurable resistor. Nanoscale devices using dense and regular fabrics such as Memristor cross-bar is promising new architecture for System-on-Chip (SoC) implementations in terms of not only the integration density that the technology can offer but also both improved performance and reduced power dissipation. Memristor has the capacity to switch between high and low resistance states in a cross-bar circuit configuration. The cross-bars are formed from an array of vertical conductive nano-wires cross a second array of horizontal conductive wires. Memristors are realized at the intersection of the two wires in the array through appropriate processing technology such that any particular wire in the vertical array can be connected to a wire in the horizontal array by switching the resistance of a particular intersection to a low state while other cross-points remain in a high resistance state. However the approach introduces a number of challenges. The lack of voltage gain prevents logic being cascaded and voltage level degradation affects robustness of the operation. Moreover the cross-bars introduce sneak current paths when two or more cross points are connected through the switched Memristor. In this paper, we propose Memristor-based programmable logic array (PLA) architecture and develop an analytical model to analyze the logic level on the memristive networks. The proposed PLA architecture has 12 inputs maximum and can be cascaded for more input variables with R(off)/R(on) ratio in the range from 55 to 160 of Memristors.

Multiple regulation by external ATP of nifedipine-insensitive, high voltage-activated Ca(2+) current in guinea-pig mesenteric terminal arteriole.

PubMed

Morita, Hiromitsu; Sharada, Thapaliya; Takewaki, Tadashi; Ito, Yushi; Inoue, Ryuji

2002-03-15

We investigated the receptor-mediated regulation of nifedipine-insensitive, high voltage-activated Ca(2+) currents in guinea-pig terminal mesenteric arterioles (I(mVDCC)) using the whole-cell clamp technique. Screening of various vasoactive substances revealed that ATP, histamine and substance P exert modulatory effects on I(mVDCC). The effects of ATP on I(mVDCC) after complete P2X receptor desensitization exhibited a complex concentration dependence. With 5 mM Ba(2+), ATP potentiated I(mVDCC) at low concentrations (approximately 1-100 microM), but inhibited it at higher concentrations (>100 microM). The potentiating effects of ATP were abolished by suramin (100 microM) and PPADS (10 microM) and by intracellular application of GDPbetaS (500 microM), whereas a substantial part of I(mVDCC) inhibition by milimolar concentrations of ATP remained unaffected; due probably to its divalent cation chelating actions. In divalent cation-free solution, I(mVDCC) was enlarged and underwent biphasic effects by ATPgammaS and ADP, while 2-methylthio ATP (2MeSATP) exerted only inhibition, and pyrimidines such as UTP and UDP were ineffective. ATP-induced I(mVDCC) potentiation was selectively inhibited by anti-Galpha(s) antibodies or protein kinase A (PKA) inhibitory peptides and mimicked by dibutyryl cAMP. In contrast, ATP-induced inhibition was selectively inhibited by Galpha(q/11) antibodies or protein kinase C (PKC) inhibitory peptides and mimicked by PDBu. Pretreatment with pertussis toxin was ineffective. The apparent efficacy for I(mVDCC) potentiation with PKC inhibitors was: ATPgammaS > ATP>/=ADP and for inhibition with PKA inhibitors was: 2MeSATP > ATPgammaS > ATP > ADP. Neither I(mVDCC) potentiation nor inhibition showed voltage dependence. These results suggest that I(mVDCC) is multi-phasically regulated by external ATP via P2Y(11)-resembling receptor/G(s)/PKA pathway, P2Y(1)-like receptor/G(q/11)/PKC pathway, and metal chelation.

Electrophysiology of pumpkin seeds: Memristors in vivo.

PubMed

Volkov, Alexander G; Nyasani, Eunice K; Tuckett, Clayton; Greeman, Esther A; Markin, Vladislav S

2016-01-01

Leon Chua, the discoverer of a memristor, theoretically predicted that voltage gated ion channels can be memristors. We recently found memristors in different plants such as the Venus flytrap, Mimosa pudica, Aloe vera, apple fruits, and in potato tubers. There are no publications in literature about the existence of memristors in seeds. The goal of this work was to discover if pumpkin seeds might have memristors. We selected Cucurbita pepo L., cv. Cinderella, Cucurbita maxima L. cv Warty Goblin, and Cucurbita maxima L., cv. Jarrahdale seeds for this analysis. In these seeds, we found the presence of resistors with memory. The analysis was based on cyclic voltammetry where a memristor should manifest itself as a nonlinear two-terminal electrical element, which exhibits a pinched hysteresis loop on a current-voltage plane for any bipolar cyclic voltage input signal. Dry dormant pumpkin seeds have very high electrical resistance without memristive properties. The electrostimulation by bipolar sinusoidal or triangular periodic waves induces electrical responses in imbibed pumpkin seeds with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K(+) channels, transforms a memristor to a resistor in pumpkin seeds. NPPB (5-Nitro-2-(3-phenylpropylamino)benzoic acid) inhibits the memristive properties of imbibed pumpkin seeds. The discovery of memristors in pumpkin seeds creates a new direction in the understanding of electrophysiological phenomena in seeds.

Integration of offshore wind farms through high voltage direct current networks

NASA Astrophysics Data System (ADS)

Livermore, Luke

The integration of offshore wind farms through Multi Terminal DC (MTDC) networks into the GB network was investigated. The ability of Voltage Source Converter (VSC) High Voltage Direct Current (HVDC) to damp Subsynchronous Resonance (SSR) and ride through onshore AC faults was studied. Due to increased levels of wind generation in Scotland, substantial onshore and offshore reinforcements to the GB transmission network are proposed. Possible inland reinforcements include the use of series compensation through fixed capacitors. This potentially can lead to SSR. Offshore reinforcements are proposed by two HVDC links. In addition to its primary functions of bulk power transmission, a HVDC link can be used to provide damping against SSR, and this function has been modelled. Simulation studies have been carried out in PSCAD. In addition, a real-time hardware-in-the-loop HVDC test rig has been used to implement and validate the proposed damping scheme on an experimental platform. When faults occur within AC onshore networks, offshore MTDC networks are vulnerable to DC overvoltages, potentially damaging the DC plant and cables. Power reduction and power dissipation control systems were investigated to ride through onshore AC faults. These methods do not require dedicated fast communication systems. Simulations and laboratory experiments are carried out to evaluate the control systems, with the results from the two platforms compared..

Three-junction solar cell

DOEpatents

Ludowise, Michael J.

1986-01-01

A photovoltaic solar cell is formed in a monolithic semiconductor. The cell contains three junctions. In sequence from the light-entering face, the junctions have a high, a medium, and a low energy gap. The lower junctions are connected in series by one or more metallic members connecting the top of the lower junction through apertures to the bottom of the middle junction. The upper junction is connected in voltage opposition to the lower and middle junctions by second metallic electrodes deposited in holes 60 through the upper junction. The second electrodes are connected to an external terminal.

Shields for protecting cables from the effects of electromagnetic noise and interference

NASA Astrophysics Data System (ADS)

Hoeft, L. O.; Hofstra, J. S.; Karaskiewicz, R. J.; Torres, B. W.

1988-12-01

The intrinsic electromagnetic property of a cable or connector shield is its surface transfer impedance. This is the ratio of the longitudinal open circuit voltage measured on one side of the shield (normally the inside) to the axial current on the other side (normally the outside). In cases where a high electric field is present at the surface of the shield, the transfer admittance or charge transfer elastance is also important. Measurements of typical cables, connectors, backshells and cable terminations are presented and explained in terms of simple models.

KEY COMPARISON Bilateral comparison of 1.018 V and 10 V standards between the NSAI-NML (Ireland) and the BIPM, March to April 2010 (part of the ongoing BIPM key comparison BIPM.EM-K11.a and b)

NASA Astrophysics Data System (ADS)

Power, O.; Solve, S.; Chayramy, R.; Stock, M.

2010-01-01

As a part of the ongoing BIPM key comparisons BIPM.EM-K11.a and b, a comparison of the 1.018 V and 10 V voltage reference standards of the BIPM and of the National Standards Authority of Ireland-National Metrology Laboratory (NSAI-NML), Dublin, Ireland, was carried out from March to April 2010. Two BIPM Zener diode-based travelling standards were transported by freight to NSAI-NML. At NSAI-NML, the reference standard for DC voltage is maintained at the 10 V level by means of a group of characterized Zener diode-based electronic voltage standards. The output EMF of each travelling standard, at the 10 V output terminals, was measured by direct comparison with the group standard. Measurements of the output EMF of the travelling standards at the 1.018 V output terminals were made using a potentiometer, standardized against the local 10 V reference standard. At the BIPM, the travelling standards were calibrated at both voltages before and after the measurements at NSAI-NML, using the BIPM Josephson Voltage Standard. Results of all measurements were corrected for the dependence of the output voltages on internal temperature and ambient pressure. The comparison results show that the voltage standards maintained by NSAI-NML and the BIPM were equivalent, within their stated expanded uncertainties, on the mean date of the comparison. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Non-linear amplification of graded voltage signals in the first-order visual interneurons of the butterfly Papilio xuthus.

PubMed

Rusanen, Juha; Frolov, Roman; Weckström, Matti; Kinoshita, Michiyo; Arikawa, Kentaro

2018-04-30

Lamina monopolar cells (LMCs) are the first-order visual interneurons of insects and crustacea, primarily involved in achromatic vision. Here we investigated morphological and electrophysiological properties of LMCs in the butterfly Papilio xuthus Using intracellular recording coupled with dye injection, we found two types of LMCs. Cells with roundish terminals near the distal surface of the medulla demonstrating no or small depolarizing spikes were classified as L1/2. LMCs with elongated terminals deep in the medulla that showed prominent spiking were classified as L3/4. The majority of LMCs of both types had broad spectral sensitivities, peaking between 480 and 570 nm. Depending on the experimental conditions, spikes varied from small to action potential-like events, with their amplitudes and rates decreasing as stimulus brightness increased. When the eye was stimulated with naturalistic contrast-modulated time series, spikes were reliably triggered by high-contrast components of the stimulus. Spike-triggered average functions showed that spikes emphasize rapid membrane depolarizations. Our results suggest that spikes are mediated by voltage-activated Na + channels, which are mainly inactivated at rest. Strong local minima in the coherence functions of spiking LMCs indicate that the depolarizing conductance contributes to the amplification of graded responses even when detectable spikes are not evoked. We propose that the information transfer strategies of spiking LMCs change with light intensity. In dim light, both graded voltage signals and large spikes are used together without mutual interference, due to separate transmission bandwidths. In bright light, signals are non-linearly amplified by the depolarizing conductance in the absence of detectable spikes. © 2018. Published by The Company of Biologists Ltd.

Rectified Proton Grotthuss Conduction Across a Long Water-Wire in the Test Nanotube of the Polytheonamide B Channel.

PubMed

Matsuki, Yuka; Iwamoto, Masayuki; Mita, Kenichiro; Shigemi, Kenji; Matsunaga, Shigeki; Oiki, Shigetoshi

2016-03-30

A hydrogen-bonded water-chain in a nanotube is highly proton conductive, and examining the proton flux under electric fields is crucial to understanding the one-dimensional Grotthuss conduction. Here, we exploited a nanotube-forming natural product, the peptide polytheonamide B (pTB), to examine proton conduction mechanisms at a single-molecule level. The pTB nanotube has a length of ∼40 Å that spans the membrane and a uniform inner diameter of 4 Å that holds a single-file water-chain. Single-channel proton currents were measured using planar lipid bilayers in various proton concentrations and membrane potentials (±400 mV). We found, surprisingly, that the current-voltage curves were asymmetric with symmetric proton concentrations in both solutions across the membrane (rectification). The proton flux from the C-terminal to the N-terminal end was 1.6 times higher than that from the opposite. At lower proton concentrations, the degree of rectification was attenuated, but with the addition of a pH-buffer (dichloroacetate) that supplies protons near the entrance, the rectification emerged. These results indicate that the permeation processes inside the pore generate the rectification, which is masked at low concentrations by the diffusion-limited access of protons to the pore entrance. The permeation processes were characterized by a discrete-state Markov model, in which hops of a proton followed by water-chain turnovers were implemented. The optimized model revealed that the water-chain turnover exhibited unusual voltage dependence, and the distinct voltage-dependencies of the forward and backward transition rates yielded the rectification. The pTB nanotube serves as a rectified proton conductor, and the design principles can be exploited for proton-conducting materials.

Change control microcomputer device for vehicle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morishita, M.; Kouge, S.

1986-08-19

A charge control microcomputer device for a vehicle is described which consists of: a clutch device for transmitting the rotary output of an engine; a charging generator driven by the clutch device; a battery charged by an output of the charging generator; a voltage regulator for controlling an output voltage of the charging generator to a predetermined value; an engine controlling microcomputer for receiving engine data, to control the engine; and a charge control microcomputer for processing the engine data from the engine controlling microcomputer and charge system data including terminal voltage data from the battery and generated voltage datamore » from the charging generator, to determine a reference voltage for the voltage regulator in accordance with the engine data and the charge system data, and for processing an engine rotation signal to generate and apply an operating instruction to the clutch device in accordance with the engine data and the charge system data, such that the charging generator is driven within a predetermined range of revolutions per minute at all times.« less

Coupling between the Voltage-sensing and Pore Domains in a Voltage-gated Potassium Channel

PubMed Central

Schow, Eric V.; Freites, J. Alfredo; Nizkorodov, Alex; White, Stephen H.; Tobias, Douglas J.

2012-01-01

Voltage-dependent potassium (Kv), sodium (Nav), and calcium channels open and close in response to changes in transmembrane (TM) potential, thus regulating cell excitability by controlling ion flow across the membrane. An outstanding question concerning voltage gating is how voltage-induced conformational changes of the channel voltage-sensing domains (VSDs) are coupled through the S4-S5 interfacial linking helices to the opening and closing of the pore domain (PD). To investigate the coupling between the VSDs and the PD, we generated a closed Kv channel configuration from Aeropyrum pernix (KvAP) using atomistic simulations with experiment-based restraints on the VSDs. Full closure of the channel required, in addition to the experimentally determined TM displacement, that the VSDs be displaced both inwardly and laterally around the PD. This twisting motion generates a tight hydrophobic interface between the S4-S5 linkers and the C-terminal ends of the pore domain S6 helices in agreement with available experimental evidence. PMID:22425907

Coupling between the voltage-sensing and pore domains in a voltage-gated potassium channel.

PubMed

Schow, Eric V; Freites, J Alfredo; Nizkorodov, Alex; White, Stephen H; Tobias, Douglas J

2012-07-01

Voltage-dependent potassium (Kv), sodium (Nav), and calcium channels open and close in response to changes in transmembrane (TM) potential, thus regulating cell excitability by controlling ion flow across the membrane. An outstanding question concerning voltage gating is how voltage-induced conformational changes of the channel voltage-sensing domains (VSDs) are coupled through the S4-S5 interfacial linking helices to the opening and closing of the pore domain (PD). To investigate the coupling between the VSDs and the PD, we generated a closed Kv channel configuration from Aeropyrum pernix (KvAP) using atomistic simulations with experiment-based restraints on the VSDs. Full closure of the channel required, in addition to the experimentally determined TM displacement, that the VSDs be displaced both inwardly and laterally around the PD. This twisting motion generates a tight hydrophobic interface between the S4-S5 linkers and the C-terminal ends of the pore domain S6 helices in agreement with available experimental evidence.

Job Language Performance Requirements for MOS 31M, Multichannel Communications Equipment Operator, Reference Soldier’s Manual Dated 3 March 1978.

DTIC Science & Technology

1978-03-03

TD -204 TD ...radio repeater set retuning ringing equipment signal cables systems lineup j" TA-312/PT TD -204/U i =" " . "J- m~l,. -- ’+- t,,m. + m~l ,,: : J...8217 " "+ . . . . • " + "A Tech cont TD -754/G telephone terminal terminal applicationsterminal lineup test cables voltage checks (p. k .’- - ~ - ~ - ’--

Pulsed electromagnetic gas acceleration

NASA Technical Reports Server (NTRS)

Jahn, R. G.; Vonjaskowsky, W. F.; Clark, K. E.

1975-01-01

Terminal voltage measurements with long cathodes in a high power, quasi-steady MPD discharge show that the critical current for the onset of voltage fluctuations, which was previously shown to be a function of cathode area, approaches an asymptote for cathodes of very large surface area. Floating potential measurements and photographs of the discharge luminosity indicate that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance. Photoelectric measurements of particular argon neutral and ion transitions show that the higher electronic states are populated more heavily than would be calculated on the basis of Saha-Boltzmann equilibrium at the local electron temperature and number density. Preliminary optical depth measurements show that for a current of 4 kA and an argon mass flow of 12 g/sec, a population inversion exists between the upper and lower states of the 4880 A argon ion transition.

Impact of open-core threading dislocations on the performance of AlGaN metal-semiconductor-metal photodetectors

NASA Astrophysics Data System (ADS)

Walde, S.; Brendel, M.; Zeimer, U.; Brunner, F.; Hagedorn, S.; Weyers, M.

2018-04-01

The influence of open-core threading dislocations on the bias-dependent external quantum efficiency (EQE) of bottom-illuminated Al0.5Ga0.5N/AlN metal-semiconductor-metal (MSM) photodetectors (PDs) is presented. These defects originate at the Al0.5Ga0.5N/AlN interface and terminate on the Al0.5Ga0.5N surface as hexagonal prisms. They work as electrically active paths bypassing the Al0.5Ga0.5N absorber layer and therefore alter the behavior of the MSM PDs under bias voltage. This effect is included in the model of carrier collection in the MSM PDs showing a good agreement with the experimental data. While such dislocations usually limit the device performance, the MSM PDs benefit by high EQE at a reduced bias voltage while maintaining a low dark current.

Identification of PN1, a Predominant Voltage-Dependent Sodium Channel Expressed Principally in Peripheral Neurons

NASA Astrophysics Data System (ADS)

Toledo-Aral, Juan J.; Moss, Brenda L.; He, Zhi-Jun; Koszowski, Adam G.; Whisenand, Teri; Levinson, Simon R.; Wolf, John J.; Silos-Santiago, Inmaculada; Halegoua, Simon; Mandel, Gail

1997-02-01

Membrane excitability in different tissues is due, in large part, to the selective expression of distinct genes encoding the voltage-dependent sodium channel. Although the predominant sodium channels in brain, skeletal muscle, and cardiac muscle have been identified, the major sodium channel types responsible for excitability within the peripheral nervous system have remained elusive. We now describe the deduced primary structure of a sodium channel, peripheral nerve type 1 (PN1), which is expressed at high levels throughout the peripheral nervous system and is targeted to nerve terminals of cultured dorsal root ganglion neurons. Studies using cultured PC12 cells indicate that both expression and targeting of PN1 is induced by treatment of the cells with nerve growth factor. The preferential localization suggests that the PN1 sodium channel plays a specific role in nerve excitability.

Memristors in the electrical network of Aloe vera L.

PubMed Central

Volkov, Alexander G; Reedus, Jada; Mitchell, Colee M; Tucket, Clayton; Forde-Tuckett, Victoria; Volkova, Maya I; Markin, Vladislav S; Chua, Leon

2014-01-01

A memristor is a resistor with memory, which is a non-linear passive two-terminal electrical element relating magnetic flux linkage and electrical charge. Here we found that memristors exist in vivo. The electrostimulation of the Aloe vera by bipolar sinusoidal or triangle periodic waves induce electrical responses with fingerprints of memristors. Uncouplers carbonylcyanide-3-chlorophenylhydrazone and carbonylcyanide-4-trifluoromethoxy-phenyl hydrazone decrease the amplitude of electrical responses at low and high frequencies of bipolar periodic sinusoidal or triangle electrostimulating waves. Memristive behavior of an electrical network in the Aloe vera is linked to the properties of voltage gated ion channels: the K+ channel blocker TEACl reduces the electric response to a conventional resistor. Our results demonstrate that a voltage gated K+ channel in the excitable tissue of plants has properties of a memristor. The discovery of memristors in plants creates a new direction in the modeling and understanding of electrical phenomena in plants. PMID:25763487

Nonequilibrium Second-Order Phase Transition in a Cooper-Pair Insulator.

PubMed

Doron, A; Tamir, I; Mitra, S; Zeltzer, G; Ovadia, M; Shahar, D

2016-02-05

In certain disordered superconductors, upon increasing the magnetic field, superconductivity terminates with a direct transition into an insulating phase. This phase is comprised of localized Cooper pairs and is termed a Cooper-pair insulator. The current-voltage characteristics measured in this insulating phase are highly nonlinear and, at low temperatures, exhibit abrupt current jumps. Increasing the temperature diminishes the jumps until the current-voltage characteristics become continuous. We show that a direct correspondence exists between our system and systems that undergo an equilibrium, second-order, phase transition. We illustrate this correspondence by comparing our results to the van der Waals equation of state for the liquid-gas mixture. We use the similarities to identify a critical point where an out of equilibrium second-order-like phase transition occurs in our system. Approaching the critical point, we find a power-law behavior with critical exponents that characterizes the transition.

Tests of a low-pressure switch protected by a saturating inductor

NASA Astrophysics Data System (ADS)

Lauer, E. J.; Birx, D. L.

1981-10-01

A triggered low-pressure switch was tested switching a charged capacitor across a damping resistor simulating a transformer. A series saturating inductor protected the switch from electron beam anode damage. The capacitor was 15 micro F and charge voltages up to 50 kV were used. The time to current maximum was 5 to 8 micro S. The current terminated at about 50 micro S and voltage could be reapplied at about 100 micro S.

Precision absolute-value amplifier for a precision voltmeter

DOEpatents

Hearn, W.E.; Rondeau, D.J.

1982-10-19

Bipolar inputs are afforded by the plus inputs of first and second differential input amplifiers. A first gain determining resistor is connected between the minus inputs of the differential amplifiers. First and second diodes are connected between the respective minus inputs and the respective outputs of the differential amplifiers. First and second FETs have their gates connected to the outputs of the amplifiers, while their respective source and drain circuits are connected between the respective minus inputs and an output lead extending to a load resistor. The output current through the load resistor is proportional to the absolute value of the input voltage difference between the bipolar input terminals. A third differential amplifier has its plus input terminal connected to the load resistor. A second gain determining resistor is connected between the minus input of the third differential amplifier and a voltage source. A third FET has its gate connected to the output of the third amplifier. The source and drain circuit of the third transistor is connected between the minus input of the third amplifier and a voltage-frequency converter, constituting an output device. A polarity detector is also provided, comprising a pair of transistors having their inputs connected to the outputs of the first and second differential amplifiers. The outputs of the polarity detector are connected to gates which switch the output of the voltage-frequency converter between up and down counting outputs.

Precision absolute value amplifier for a precision voltmeter

DOEpatents

Hearn, William E.; Rondeau, Donald J.

1985-01-01

Bipolar inputs are afforded by the plus inputs of first and second differential input amplifiers. A first gain determining resister is connected between the minus inputs of the differential amplifiers. First and second diodes are connected between the respective minus inputs and the respective outputs of the differential amplifiers. First and second FETs have their gates connected to the outputs of the amplifiers, while their respective source and drain circuits are connected between the respective minus inputs and an output lead extending to a load resister. The output current through the load resister is proportional to the absolute value of the input voltage difference between the bipolar input terminals. A third differential amplifier has its plus input terminal connected to the load resister. A second gain determining resister is connected between the minus input of the third differential amplifier and a voltage source. A third FET has its gate connected to the output of the third amplifier. The source and drain circuit of the third transistor is connected between the minus input of the third amplifier and a voltage-frequency converter, constituting an output device. A polarity detector is also provided, comprising a pair of transistors having their inputs connected to the outputs of the first and second differential amplifiers. The outputs of the polarity detector are connected to gates which switch the output of the voltage-frequency converter between up and down counting outputs.

Radiometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strickland, J. I.

1985-07-02

A radiometer of the switched type has an R.F. switch connecting a detector selectively either to an antenna whose temperature (in terms of noise energy) is to be determined, or to a reference temperature, i.e. a resistive termination. The detector output is passed through an amplifier whose gain is switched between positive and negative values (for example +1 and -1) synchronously with the R.F. switch. The output of the switched gain amplifier is integrated to produce a rising voltage when the gain is positive and a falling one when it is negative. When it is positive the detector is connectedmore » to the antenna. By means of a zero crossing detector, a counter is started when this voltage crosses zero. After a fixed period, the R.F. switch and switched gain amplifier are reversed by the counter to cause the voltage to fall in accordance with the temperature of the resistive termination. The zero crossing detector and a counter measure the time interval until the voltage again crosses zero, such time interval being compared to the fixed period to provide a comparison of the unknown and reference temperatures independent of the gain of the detector, which is a valuable improvement over prior radiometers. Also, by measuring time rather than voltage, the arrangement facilitates providing a digital output more suitable for storage and transmission of the data than the analog output of prior radiometers. The instrument, which is relatively simple, rugged and compact, lends itself well to unattended use in monitoring the effect of rain storms on transmission in the 11.7 to 12.2 GHz band employed for satelite communication.« less

Observation of electrostatically released DNA from gold electrodes with controlled threshold voltages.

PubMed

Takeishi, Shunsaku; Rant, Ulrich; Fujiwara, Tsuyoshi; Buchholz, Karin; Usuki, Tatsuya; Arinaga, Kenji; Takemoto, Kazuya; Yamaguchi, Yoshitaka; Tornow, Marc; Fujita, Shozo; Abstreiter, Gerhard; Yokoyama, Naoki

2004-03-22

DNA oligo-nucleotides, localized at Au metal electrodes in aqueous solution, are found to be released when applying a negative bias voltage to the electrode. The release was confirmed by monitoring the intensity of the fluorescence of cyanine dyes (Cy3) linked to the 5' end of the DNA. The threshold voltage of the release changes depending on the kind of linker added to the DNA 3'-terminal. The amount of released DNA depends on the duration of the voltage pulse. Using this technique, we can retain DNA at Au electrodes or Au needles, and release the desired amount of DNA at a precise location in a target. The results suggest that DNA injection into living cells is possible with this method. (c) 2004 American Institute of Physics

Origin of terminal voltage variations due to self-mixing in terahertz frequency quantum cascade lasers.

PubMed

Grier, Andrew; Dean, Paul; Valavanis, Alexander; Keeley, James; Kundu, Iman; Cooper, Jonathan D; Agnew, Gary; Taimre, Thomas; Lim, Yah Leng; Bertling, Karl; Rakić, Aleksandar D; Li, Lianhe H; Harrison, Paul; Linfield, Edmund H; Ikonić, Zoran; Davies, A Giles; Indjin, Dragan

2016-09-19

We explain the origin of voltage variations due to self-mixing in a terahertz (THz) frequency quantum cascade laser (QCL) using an extended density matrix (DM) approach. Our DM model allows calculation of both the current-voltage (I-V) and optical power characteristics of the QCL under optical feedback by changing the cavity loss, to which the gain of the active region is clamped. The variation of intra-cavity field strength necessary to achieve gain clamping, and the corresponding change in bias required to maintain a constant current density through the heterostructure is then calculated. Strong enhancement of the self-mixing voltage signal due to non-linearity of the (I-V) characteristics is predicted and confirmed experimentally in an exemplar 2.6 THz bound-to-continuum QCL.

Time-resolved magnetic spectrometer measurements of the SABRE positive polarity magnetically insulated transmission line voltage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menge, P.R.; Cuneo, M.E.; Hanson, D.L.

A magnetic spectrometer has been fielded on the coaxial magnetically insulated transmission line (MITL) of the SABRE ten-cavity inductive voltage adder operated in positive polarity (6 MV, 300 kA, 50 ns). Located 1 m upstream from an extraction ion diode, this diagnostic is capable of measuring the SABRE voltage pulse with a 2 ns resolution. Ions (protons and carbon) from either a flashover or plasma gun source are accelerated from the inner anode across the gap to the outer cathode and into a drift tube terminated by the magnetic spectrometer. The magnetically deflected ions are recorded on up to sixteenmore » PIN diodes (diameter = 1 mm, thickness = 35 {mu}). The voltage waveform is produced from the time-of-flight information. Results confirm previous observations of a vacuum wave precursor separated from the magnetically insulated wave. Verification of upstream precursor erosion techniques are possible with this instrument. Measurements of peak voltage show good agreement with other time-integrated voltage diagnostics. Comparisons with theoretical voltage predictions derived from a flow impedance model of MITL behavior will be presented.« less

Highly Stable, Dual-Gated MoS2 Transistors Encapsulated by Hexagonal Boron Nitride with Gate-Controllable Contact, Resistance, and Threshold Voltage.

PubMed

Lee, Gwan-Hyoung; Cui, Xu; Kim, Young Duck; Arefe, Ghidewon; Zhang, Xian; Lee, Chul-Ho; Ye, Fan; Watanabe, Kenji; Taniguchi, Takashi; Kim, Philip; Hone, James

2015-07-28

Emerging two-dimensional (2D) semiconductors such as molybdenum disulfide (MoS2) have been intensively studied because of their novel properties for advanced electronics and optoelectronics. However, 2D materials are by nature sensitive to environmental influences, such as temperature, humidity, adsorbates, and trapped charges in neighboring dielectrics. Therefore, it is crucial to develop device architectures that provide both high performance and long-term stability. Here we report high performance of dual-gated van der Waals (vdW) heterostructure devices in which MoS2 layers are fully encapsulated by hexagonal boron nitride (hBN) and contacts are formed using graphene. The hBN-encapsulation provides excellent protection from environmental factors, resulting in highly stable device performance, even at elevated temperatures. Our measurements also reveal high-quality electrical contacts and reduced hysteresis, leading to high two-terminal carrier mobility (33-151 cm(2) V(-1) s(-1)) and low subthreshold swing (80 mV/dec) at room temperature. Furthermore, adjustment of graphene Fermi level and use of dual gates enable us to separately control contact resistance and threshold voltage. This novel vdW heterostructure device opens up a new way toward fabrication of stable, high-performance devices based on 2D materials.

AlN/ITO-Based Hybrid Electrodes with Conducting Filaments: Their Application to Ultraviolet Light-Emitting Diodes.

PubMed

Kim, Kyeong Heon; Lee, Tae Ho; Kim, Tae Geun

2017-07-19

A hybrid-type transparent conductive electrode (H-TCE) structure comprising an AlN rod array with conducting filaments (CFs) and indium tin oxide (ITO) films is proposed to improve both current injection and distribution as well as optical transmittance in the UV region. These CFs, generated in UV-transparent AlN rod areas using an electric field, can be used as conducting paths for carrier injection from a metal to a semiconductor such as p-(Al)GaN, which allows perfect Ohmic behavior with high transmittance (>95% at 365 nm) to be obtained. In addition, conduction across AlN rods and Ohmic conduction mechanisms are investigated by analyzing AlN rods and AlN rod/p-AlGaN film interfaces. We apply these H-TCEs to three near-UV light-emitting diodes (LEDs) (385 nm LEDs with p-GaN and p-AlGaN terminated surfaces and 365 nm LED with p-AlGaN terminated surface). We confirm that the light power outputs increase by 66%, 79%, and 103%, whereas the forward voltages reduce by 5.6%, 10.2%, and 8.6% for 385 nm p-GaN terminated, 385 nm p-AlGaN terminated, and 365 nm p-AlGaN terminated LEDs with H-TCEs, respectively, compared to LEDs with reference ITOs.

The last large pelletron accelerator of the Herb era

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chopra, S.; Narayanan, M. M.; Joshi, R.

1999-04-26

Prof. Ray Herb pioneered the concept and design of the tandem Pelletron accelerator in the late sixties at NEC. The 15UD Pelletron at Nuclear Science Centre (NSC), upgraded for 16MV operation using compressed geometry accelerating tubes is the last such large Pelletron. It has unique features like offset and matching quadrupoles after the stripper for charge state selection inside the high voltage terminal and consequently the option of further stripping the ion species of the selected charge states at high energy dead section, and elaborate pulsing system in the pre-acceleration region consisting of a beam chopper, a travelling wave deflector,more » a light ion buncher (1-80 amu) and a heavy ion buncher (>80 amu). NSC was established as a heavy ion accelerator based inter university centre in 1985. It became operational in July 1991 to cater to the research requirements of a large user community which at present includes about fifty universities, twenty-eight colleges and a dozen other academic institutes and research laboratories. The number of users in Materials and allied sciences is about 500. Various important modifications have been made to improve the performance of the accelerator in the last seven years. These include replacement of the corona voltage grading system by a resistor based one, a pick-up loop to monitor charging system performance, conversion from basic double unit structure to singlet, installation of a spiral cavity based phase detector system with post-accelerator stripper after the analyzing magnet, and a high efficiency multi harmonic buncher. Installation of a turbo pump based stripper gas recirculation system in the terminal is also planned. A brief description of utilization of the machine will be given.« less

Multi-terminal memtransistors from polycrystalline monolayer molybdenum disulfide

NASA Astrophysics Data System (ADS)

Sangwan, Vinod K.; Lee, Hong-Sub; Bergeron, Hadallia; Balla, Itamar; Beck, Megan E.; Chen, Kan-Sheng; Hersam, Mark C.

2018-02-01

Memristors are two-terminal passive circuit elements that have been developed for use in non-volatile resistive random-access memory and may also be useful in neuromorphic computing. Memristors have higher endurance and faster read/write times than flash memory and can provide multi-bit data storage. However, although two-terminal memristors have demonstrated capacity for basic neural functions, synapses in the human brain outnumber neurons by more than a thousandfold, which implies that multi-terminal memristors are needed to perform complex functions such as heterosynaptic plasticity. Previous attempts to move beyond two-terminal memristors, such as the three-terminal Widrow-Hoff memristor and field-effect transistors with nanoionic gates or floating gates, did not achieve memristive switching in the transistor. Here we report the experimental realization of a multi-terminal hybrid memristor and transistor (that is, a memtransistor) using polycrystalline monolayer molybdenum disulfide (MoS2) in a scalable fabrication process. The two-dimensional MoS2 memtransistors show gate tunability in individual resistance states by four orders of magnitude, as well as large switching ratios, high cycling endurance and long-term retention of states. In addition to conventional neural learning behaviour of long-term potentiation/depression, six-terminal MoS2 memtransistors have gate-tunable heterosynaptic functionality, which is not achievable using two-terminal memristors. For example, the conductance between a pair of floating electrodes (pre- and post-synaptic neurons) is varied by a factor of about ten by applying voltage pulses to modulatory terminals. In situ scanning probe microscopy, cryogenic charge transport measurements and device modelling reveal that the bias-induced motion of MoS2 defects drives resistive switching by dynamically varying Schottky barrier heights. Overall, the seamless integration of a memristor and transistor into one multi-terminal device could enable complex neuromorphic learning and the study of the physics of defect kinetics in two-dimensional materials.

A comprehensive equivalent circuit model of all-vanadium redox flow battery for power system analysis

NASA Astrophysics Data System (ADS)

Zhang, Yu; Zhao, Jiyun; Wang, Peng; Skyllas-Kazacos, Maria; Xiong, Binyu; Badrinarayanan, Rajagopalan

2015-09-01

Electrical equivalent circuit models demonstrate excellent adaptability and simplicity in predicting the electrical dynamic response of the all-vanadium redox flow battery (VRB) system. However, only a few publications that focus on this topic are available. The paper presents a comprehensive equivalent circuit model of VRB for system level analysis. The least square method is used to identify both steady-state and dynamic characteristics of VRB. The inherent features of the flow battery such as shunt current, ion diffusion and pumping energy consumption are also considered. The proposed model consists of an open-circuit voltage source, two parasitic shunt bypass circuits, a 1st order resistor-capacitor network and a hydraulic circuit model. Validated with experimental data, the proposed model demonstrates excellent accuracy. The mean-error of terminal voltage and pump consumption are 0.09 V and 0.49 W respectively. Based on the proposed model, self-discharge and system efficiency are studied. An optimal flow rate which maximizes the system efficiency is identified. Finally, the dynamic responses of the proposed VRB model under step current profiles are presented. Variables such as SOC and stack terminal voltage can be provided.

Static Noise Margin Enhancement by Flex-Pass-Gate SRAM

NASA Astrophysics Data System (ADS)

O'Uchi, Shin-Ichi; Masahara, Meishoku; Sakamoto, Kunihiro; Endo, Kazuhiko; Liu, Yungxun; Matsukawa, Takashi; Sekigawa, Toshihiro; Koike, Hanpei; Suzuki, Eiichi

A Flex-Pass-Gate SRAM, i.e. a fin-type-field-effect-transistor- (FinFET-) based SRAM, is proposed to enhance noise margin during both read and write operations. In its cell, the flip-flop is composed of usual three-terminal- (3T-) FinFETs while pass gates are composed of four-terminal- (4T-) FinFETs. The 4T-FinFETs enable to adopt a dynamic threshold-voltage control in the pass gates. During a write operation, the threshold voltage of the pass gates is lowered to enhance the writing speed and stability. During the read operation, on the other hand, the threshold voltage is raised to enhance the static noise margin. An asymmetric-oxide 4T-FinFET is helpful to manage the leakage current through the pass gate. In this paper, a design strategy of the pass gate with an asymmetric gate oxide is considered, and a TCAD-based Monte Carlo simulation reveals that the Flex-Pass-Gate SRAM based on that design strategy is expected to be effective in half-pitch 32-nm technology for low-standby-power (LSTP) applications, even taking into account the variability in the device performance.

Charge Carrier Transport Mechanism Based on Stable Low Voltage Organic Bistable Memory Device.

PubMed

Ramana, V V; Moodley, M K; Kumar, A B V Kiran; Kannan, V

2015-05-01

A solution processed two terminal organic bistable memory device was fabricated utilizing films of polymethyl methacrylate PMMA/ZnO/PMMA on top of ITO coated glass. Electrical characterization of the device structure showed that the two terminal device exhibited favorable switching characteristics with an ON/OFF ratio greater than 1 x 10(4) when the voltage was swept between - 2 V and +3 V. The device maintained its state after removal of the bias voltage. The device did not show degradation after a 1-h retention test at 120 degrees C. The memory functionality was consistent even after fifty cycles of operation. The charge transport switching mechanism is discussed on the basis of carrier transport mechanism and our analysis of the data shows that the charge carrier trans- port mechanism of the device during the writing process can be explained by thermionic emission (TE) and space-charge-limited-current (SCLC) mechanism models while erasing process could be explained by the FN tunneling mechanism. This demonstration provides a class of memory devices with the potential for low-cost, low-power consumption applications, such as a digital memory cell.

Understanding of self-terminating pulse generation using silicon controlled rectifier and RC load

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Chris, E-mail: chrischang81@gmail.com; Karunasiri, Gamani, E-mail: karunasiri@nps.edu; Alves, Fabio, E-mail: falves@alionscience.com

2016-01-15

Recently a silicon controlled rectifier (SCR)-based circuit that generates self-terminating voltage pulses was employed for the detection of light and ionizing radiation in pulse mode. The circuit consisted of a SCR connected in series with a RC load and DC bias. In this paper, we report the investigation of the physics underlying the pulsing mechanism of the SCR-based. It was found that during the switching of SCR, the voltage across the capacitor increased beyond that of the DC bias, thus generating a reverse current in the circuit, which helped to turn the SCR off. The pulsing was found to bemore » sustainable only for a specific range of RC values depending on the SCR’s intrinsic turn-on/off times. The findings of this work will help to design optimum SCR based circuits for pulse mode detection of light and ionizing radiation without external amplification circuitry.« less

Shielding effectiveness of multiple-shield cables with arbitrary terminations via transmission line analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campione, Salvatore; Basilio, Lorena I.; Warne, Larry Kevin

Our paper reports on a transmission-line model for calculating the shielding effectiveness of multiple-shield cables with arbitrary terminations. Since the shields are not perfect conductors and apertures in the shields permit external magnetic and electric fields to penetrate into the interior regions of the cable, we use this model to estimate the effects of the outer shield current and voltage (associated with the external excitation and boundary conditions associated with the external conductor) on the inner conductor current and voltage. It is commonly believed that increasing the number of shields of a cable will improve the shielding performance. But thismore » is not always the case, and a cable with multiple shields may perform similar to or worse than a cable with a single shield. Furthermore, we want to shed more light on these situations, which represent the main focus of this paper.« less

Device, system and method for a sensing electrical circuit

NASA Technical Reports Server (NTRS)

Vranish, John M. (Inventor)

2009-01-01

The invention relates to a driven ground electrical circuit. A driven ground is a current-measuring ground termination to an electrical circuit with the current measured as a vector with amplification. The driven ground module may include an electric potential source V.sub.S driving an electric current through an impedance (load Z) to a driven ground. Voltage from the source V.sub.S excites the minus terminal of an operational amplifier inside the driven ground which, in turn, may react by generating an equal and opposite voltage to drive the net potential to approximately zero (effectively ground). A driven ground may also be a means of passing information via the current passing through one grounded circuit to another electronic circuit as input. It may ground one circuit, amplify the information carried in its current and pass this information on as input to the next circuit.

System and method for determining stator winding resistance in an AC motor using motor drives

DOEpatents

Lu, Bin; Habetler, Thomas G; Zhang, Pinjia

2013-02-26

A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

Shielding effectiveness of multiple-shield cables with arbitrary terminations via transmission line analysis

DOE PAGES

Campione, Salvatore; Basilio, Lorena I.; Warne, Larry Kevin; ...

2016-06-25

Our paper reports on a transmission-line model for calculating the shielding effectiveness of multiple-shield cables with arbitrary terminations. Since the shields are not perfect conductors and apertures in the shields permit external magnetic and electric fields to penetrate into the interior regions of the cable, we use this model to estimate the effects of the outer shield current and voltage (associated with the external excitation and boundary conditions associated with the external conductor) on the inner conductor current and voltage. It is commonly believed that increasing the number of shields of a cable will improve the shielding performance. But thismore » is not always the case, and a cable with multiple shields may perform similar to or worse than a cable with a single shield. Furthermore, we want to shed more light on these situations, which represent the main focus of this paper.« less

C-Terminal residues in small potassium channel blockers OdK1 and OSK3 from scorpion venom fine-tune the selectivity.

PubMed

Kuzmenkov, Alexey I; Peigneur, Steve; Chugunov, Anton O; Tabakmakher, Valentin M; Efremov, Roman G; Tytgat, Jan; Grishin, Eugene V; Vassilevski, Alexander A

2017-05-01

We report isolation, sequencing, and electrophysiological characterization of OSK3 (α-KTx 8.8 in Kalium and Uniprot databases), a potassium channel blocker from the scorpion Orthochirus scrobiculosus venom. Using the voltage clamp technique, OSK3 was tested on a wide panel of 11 voltage-gated potassium channels expressed in Xenopus oocytes, and was found to potently inhibit Kv1.2 and Kv1.3 with IC 50 values of ~331nM and ~503nM, respectively. OdK1 produced by the scorpion Odontobuthus doriae differs by just two C-terminal residues from OSK3, but shows marked preference to Kv1.2. Based on the charybdotoxin-potassium channel complex crystal structure, a model was built to explain the role of the variable residues in OdK1 and OSK3 selectivity. Copyright © 2017 Elsevier B.V. All rights reserved.

Position and speed control of brushless DC motors using sensorless techniques and application trends.

PubMed

Gamazo-Real, José Carlos; Vázquez-Sánchez, Ernesto; Gómez-Gil, Jaime

2010-01-01

This paper provides a technical review of position and speed sensorless methods for controlling Brushless Direct Current (BLDC) motor drives, including the background analysis using sensors, limitations and advances. The performance and reliability of BLDC motor drivers have been improved because the conventional control and sensing techniques have been improved through sensorless technology. Then, in this paper sensorless advances are reviewed and recent developments in this area are introduced with their inherent advantages and drawbacks, including the analysis of practical implementation issues and applications. The study includes a deep overview of state-of-the-art back-EMF sensing methods, which includes Terminal Voltage Sensing, Third Harmonic Voltage Integration, Terminal Current Sensing, Back-EMF Integration and PWM strategies. Also, the most relevant techniques based on estimation and models are briefly analysed, such as Sliding-mode Observer, Extended Kalman Filter, Model Reference Adaptive System, Adaptive observers (Full-order and Pseudoreduced-order) and Artificial Neural Networks.

Combined electrochemical, heat generation, and thermal model for large prismatic lithium-ion batteries in real-time applications

NASA Astrophysics Data System (ADS)

Farag, Mohammed; Sweity, Haitham; Fleckenstein, Matthias; Habibi, Saeid

2017-08-01

Real-time prediction of the battery's core temperature and terminal voltage is very crucial for an accurate battery management system. In this paper, a combined electrochemical, heat generation, and thermal model is developed for large prismatic cells. The proposed model consists of three sub-models, an electrochemical model, heat generation model, and thermal model which are coupled together in an iterative fashion through physicochemical temperature dependent parameters. The proposed parameterization cycles identify the sub-models' parameters separately by exciting the battery under isothermal and non-isothermal operating conditions. The proposed combined model structure shows accurate terminal voltage and core temperature prediction at various operating conditions while maintaining a simple mathematical structure, making it ideal for real-time BMS applications. Finally, the model is validated against both isothermal and non-isothermal drive cycles, covering a broad range of C-rates, and temperature ranges [-25 °C to 45 °C].

Comprehensive electrical analysis of metal/Al2O3/O-terminated diamond capacitance

NASA Astrophysics Data System (ADS)

Pham, T. T.; Maréchal, A.; Muret, P.; Eon, D.; Gheeraert, E.; Rouger, N.; Pernot, J.

2018-04-01

Metal oxide semiconductor capacitors were fabricated using p - type oxygen-terminated (001) diamond and Al2O3 deposited by atomic layer deposition at two different temperatures 250 °C and 380 °C. Current voltage I(V), capacitance voltage C(V), and capacitance frequency C(f) measurements were performed and analyzed for frequencies ranging from 1 Hz to 1 MHz and temperatures from 160 K to 360 K. A complete model for the Metal-Oxide-Semiconductor Capacitors electrostatics, leakage current mechanisms through the oxide into the semiconductor and small a.c. signal equivalent circuit of the device is proposed and discussed. Interface states densities are then evaluated in the range of 1012eV-1cm-2 . The strong Fermi level pinning is demonstrated to be induced by the combined effects of the leakage current through the oxide and the presence of diamond/oxide interface states.

Method for electrostatic deposition of graphene on a substrate

NASA Technical Reports Server (NTRS)

Sumanasekera, Gamini (Inventor); Sidorov, Anton N. (Inventor); Ouseph, P. John (Inventor); Yazdanpanah, Mehdi M. (Inventor); Cohn, Robert W. (Inventor); Jalilian, Romaneh (Inventor)

2010-01-01

A method for electrostatic deposition of graphene on a substrate comprises the steps of securing a graphite sample to a first electrode; electrically connecting the first electrode to a positive terminal of a power source; electrically connecting a second electrode to a ground terminal of the power source; placing the substrate over the second electrode; and using the power source to apply a voltage, such that graphene is removed from the graphite sample and deposited on the substrate.

Gating electrical transport through DNA molecules that bridge between silicon nanogaps.

PubMed

Takagi, Shogo; Takada, Tadao; Matsuo, Naoto; Yokoyama, Shin; Nakamura, Mitsunobu; Yamana, Kazushige

2012-03-21

DNA electronic devices were prepared on silicon-based three-terminal electrodes. Both ends of DNA molecules (400 bp long, mixed sequences) were bridged via chemical bonds between the source-drain nanogap (120 nm) electrodes. S-Shaped I-V curves were obtained and the electric current can be modulated by the gate voltage. The DNA molecules act as semiconducting p-type nanowires in the three-terminal device. This journal is © The Royal Society of Chemistry 2012

Electrical Circuit Tester

DOEpatents

Love, Frank

2006-04-18

An electrical circuit testing device is provided, comprising a case, a digital voltage level testing circuit with a display means, a switch to initiate measurement using the device, a non-shorting switching means for selecting pre-determined electrical wiring configurations to be tested in an outlet, a terminal block, a five-pole electrical plug mounted on the case surface and a set of adapters that can be used for various multiple-pronged electrical outlet configurations for voltages from 100 600 VAC from 50 100 Hz.

Improving battery safety by early detection of internal shorting with a bifunctional separator

NASA Astrophysics Data System (ADS)

Wu, Hui; Zhuo, Denys; Kong, Desheng; Cui, Yi

2014-10-01

Lithium-based rechargeable batteries have been widely used in portable electronics and show great promise for emerging applications in transportation and wind-solar-grid energy storage, although their safety remains a practical concern. Failures in the form of fire and explosion can be initiated by internal short circuits associated with lithium dendrite formation during cycling. Here we report a new strategy for improving safety by designing a smart battery that allows internal battery health to be monitored in situ. Specifically, we achieve early detection of lithium dendrites inside batteries through a bifunctional separator, which offers a third sensing terminal in addition to the cathode and anode. The sensing terminal provides unique signals in the form of a pronounced voltage change, indicating imminent penetration of dendrites through the separator. This detection mechanism is highly sensitive, accurate and activated well in advance of shorting and can be applied to many types of batteries for improved safety.

Investigations into the use of energy storage in power system applications

NASA Astrophysics Data System (ADS)

Leung, Ka Kit

This thesis embodies research work on the design and implementation of novel fast responding battery energy storage systems, which, with sufficient capacity and rating, could remove the uncertainty in forecasting the annual peak demand. They would also benefit the day to day operation by curtailing the fastest demand variations, particularly at the daily peak periods. Energy storage that could curtail peak demands, when the most difficult operational problems occur offers a promising approach. Although AC energy cannot be stored, power electronic developments offer a fast responding interface between the AC network and DC energy stored in batteries. The attractive feature of the use of this energy storage could most effectively be located near the source of load variations, i.e. near consumers in the distribution networks. The proposed, three phase multi-purpose, Battery Energy Storage System will provide active and reactive power independent of the supply voltage with excellent power quality in terms of its waveform. Besides the above important functions applied at the distribution side of the utility, several new topologies have been developed to provide both Dynamic Voltage Regulator (DVR) and Unified Power Flow Controller (UPFC) functions for line compensation. These new topologies can provide fast and accurate control of power flow along a distribution corridor. The topologies also provide for fast damping of system oscillation due to transient or dynamic disturbances. Having demonstrated the various functions that the proposed Battery Energy Storage System can provide, the final part of the thesis investigates means of improving the performance of the proposed BESS. First, there is a need to reduce the switching losses by using soft switching instead of hard switching. A soft switching inverter using a parallel resonant dc-link (PRDCL) is proposed for use with the proposed BESS. The proposed PRDCL suppresses the dc-link voltage to zero for a very short time to allow zero voltage switching of inverter main switches without imposing excessive voltage and current stresses. Finally, in practice the battery terminal voltage fluctuates significantly as large current is being drawn or absorbed by the battery bank. When a hysteresis controller is used to control the supply line current, the ripple magnitude and frequency of the controlled current is highly dependent on the battery voltage, line inductance and the band limits of the controller. Even when these parameters are constant, the switching frequency can vary over quite a large range. A novel method is proposed to overcome this problem by controlling the dc voltage level by means of a dc-dc converter to provide a controllable voltage at the inverter dc terminal irrespective of the battery voltage variations. By proper control of the magnitude and frequency of the output of the DC-DC converter, the switching frequency can be made close to constant. A mathematical proof has been formulated and results from the simulation confirm that using the proposed technique, the frequency band has been significantly reduced and for the theoretical case, a single switching frequency is observed. The main disadvantage is the need to have an extra dc-dc converter, but this is relatively cheap and easy to obtain.

Functional analysis of a frame-shift mutant of the dihydropyridine receptor pore subunit (α1S) expressing two complementary protein fragments

PubMed Central

Ahern, Chris A; Vallejo, Paola; Mortenson, Lindsay; Coronado, Roberto

2001-01-01

Background The L-type Ca2+ channel formed by the dihydropyridine receptor (DHPR) of skeletal muscle senses the membrane voltage and opens the ryanodine receptor (RyR1). This channel-to-channel coupling is essential for Ca2+ signaling but poorly understood. We characterized a single-base frame-shift mutant of α1S, the pore subunit of the DHPR, that has the unusual ability to function voltage sensor for excitation-contraction (EC) coupling by virtue of expressing two complementary hemi-Ca2+ channel fragments. Results Functional analysis of cDNA transfected dysgenic myotubes lacking α1S were carried out using voltage-clamp, confocal Ca2+ indicator fluoresence, epitope immunofluorescence and immunoblots of expressed proteins. The frame-shift mutant (fs-α1S) expressed the N-terminal half of α1S (M1 to L670) and the C-terminal half starting at M701 separately. The C-terminal fragment was generated by an unexpected restart of translation of the fs-α1S message at M701 and was eliminated by a M701I mutation. Protein-protein complementation between the two fragments produced recovery of skeletal-type EC coupling but not L-type Ca2+ current. Discussion A premature stop codon in the II-III loop may not necessarily cause a loss of DHPR function due to a restart of translation within the II-III loop, presumably by a mechanism involving leaky ribosomal scanning. In these cases, function is recovered by expression of complementary protein fragments from the same cDNA. DHPR-RyR1 interactions can be achieved via protein-protein complementation between hemi-Ca2+ channel proteins, hence an intact II-III loop is not essential for coupling the DHPR voltage sensor to the opening of RyR1 channel. PMID:11806762

Models and methods for assessing the value of HVDC and MVDC technologies in modern power grids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makarov, Yuri V.; Elizondo, Marcelo A.; O'Brien, James G.

This report reflects the results of U.S. Department of Energy’s (DOE) Grid Modernization project 0074 “Models and methods for assessing the value of HVDC [high-voltage direct current] and MTDC [multi-terminal direct current] technologies in modern power grids.” The work was done by the Pacific Northwest National Laboratory (PNNL) and Oak Ridge National Laboratory (ORNL) in cooperation with Mid-Continent Independent System Operator (MISO) and Siemens. The main motivation of this study was to show the benefit of using direct current (DC) systems larger than those in existence today as they overlap with the alternating current (AC) systems. Proper use of theirmore » flexibility in terms of active/reactive power control and fast response can provide much-needed services to the grid at the same time as moving large blocks of energy to take advantage of cost diversity. Ultimately, the project’s success will enable decision-makers and investors to make well-informed decisions regarding this use of DC systems. This project showed the technical feasibility of HVDC macrogrid for frequency control and congestion relief in addition to bulk power transfers. Industry-established models for commonly used technologies were employed, along with high-fidelity models for recently developed HVDC converter technologies; like the modular multilevel converters (MMCs), a voltage source converters (VSC). Models for General Electric Positive Sequence Load Flow (GE PSLF) and Siemens Power System Simulator (PSS/E), widely used analysis programs, were for the first time adapted to include at the same time both Western Electricity Coordinating Council (WECC) and Eastern Interconnection (EI), the two largest North American interconnections. The high-fidelity models and their control were developed in detail for MMC system and extended to HVDC systems in point-to-point and in three-node multi-terminal configurations. Using a continental-level mixed AC-DC grid model, and using a HVDC macrogrid power flow and transient stability model, the results showed that the HVDC macrogrid relieved congestion and mitigated loop flows in AC networks, and provided up to 24% improvement in frequency responses. These are realistic studies, based on the 2025 heavy summer and EI multi-regional modeling working group (MMWG) 2026 summer peak cases. This work developed high-fidelity models and simulation algorithms to understand the dynamics of MMC. The developed models and simulation algorithms are up to 25 times faster than the existing algorithms. Models and control algorithms for high-fidelity models were designed and tested for point-to-point and multi-terminal configurations. The multi-terminal configuration was tested connecting simplified models of EI, WI, and Electric Reliability Council of Texas (ERCOT). The developed models showed up to 45% improvement in frequency response with the connection of all the three asynchronous interconnections in the United States using fast and advanced DC technologies like the multi-terminal MMC-DC system. Future work will look into developing high-fidelity models of other advanced DC technologies, combining high-fidelity models with the continental-level model, incorporating additional services. More scenarios involving large-scale HVDC and MTDC will be evaluated.« less

Three-terminal graphene single-electron transistor fabricated using feedback-controlled electroburning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puczkarski, Paweł; Gehring, Pascal, E-mail: pascal.gehring@materials.ox.ac.uk; Lau, Chit S.

2015-09-28

We report room-temperature Coulomb blockade in a single layer graphene three-terminal single-electron transistor fabricated using feedback-controlled electroburning. The small separation between the side gate electrode and the graphene quantum dot results in a gate coupling up to 3 times larger compared to the value found for the back gate electrode. This allows for an effective tuning between the conductive and Coulomb blocked state using a small side gate voltage of about 1 V. The technique can potentially be used in the future to fabricate all-graphene based room temperature single-electron transistors or three terminal single molecule transistors with enhanced gate coupling.

Superstrate sub-cell voltage-matched multijunction solar cells

DOEpatents

Mascarenhas, Angelo; Alberi, Kirstin

2016-03-15

Voltage-matched thin film multijunction solar cell and methods of producing cells having upper CdTe pn junction layers formed on a transparent substrate which in the completed device is operatively positioned in a superstate configuration. The solar cell also includes a lower pn junction formed independently of the CdTe pn junction and an insulating layer between CdTe and lower pn junctions. The voltage-matched thin film multijunction solar cells further include a parallel connection between the CdTe pn junction and lower pn junctions to form a two-terminal photonic device. Methods of fabricating devices from independently produced upper CdTe junction layers and lower junction layers are also disclosed.

Solar bus regulator and battery charger for IMP's H, I, and J

NASA Technical Reports Server (NTRS)

Paulkovich, J.

1972-01-01

Interplanetary Monitoring Probe (IMP) spacecrafts H, I, and J utilize a direct energy transfer (DET) type of power system operating from a solar array source. A shunt type of regulator prevents the bus voltage from exceeding a preset voltage level. The power system utilizes a single differential amplifier with dual outputs to control the battery charge/shunt regulator and the discharge regulator. A two-voltage level, current limited, series charger and a current sensor control battery state of charge of the silver-cadmium battery pack. Premature termination of the battery charge is prevented by a power available gate that also initiates charge current to the battery upon availability of excess power.

Dissection of the components for PIP2 activation and thermosensation in TRP channels

PubMed Central

Brauchi, Sebastian; Orta, Gerardo; Mascayano, Carolina; Salazar, Marcelo; Raddatz, Natalia; Urbina, Hector; Rosenmann, Eduardo; Gonzalez-Nilo, Fernando; Latorre, Ramon

2007-01-01

Phosphatidylinositol 4,5-bisphosphate (PIP2) plays a central role in the activation of several transient receptor potential (TRP) channels. The role of PIP2 on temperature gating of thermoTRP channels has not been explored in detail, and the process of temperature activation is largely unexplained. In this work, we have exchanged different segments of the C-terminal region between cold-sensitive (TRPM8) and heat-sensitive (TRPV1) channels, trying to understand the role of the segment in PIP2 and temperature activation. A chimera in which the proximal part of the C-terminal of TRPV1 replaces an equivalent section of TRPM8 C-terminal is activated by PIP2 and confers the phenotype of heat activation. PIP2, but not temperature sensitivity, disappears when positively charged residues contained in the exchanged region are neutralized. Shortening the exchanged segment to a length of 11 aa produces voltage-dependent and temperature-insensitive channels. Our findings suggest the existence of different activation domains for temperature, PIP2, and voltage. We provide an interpretation for channel–PIP2 interaction using a full-atom molecular model of TRPV1 and PIP2 docking analysis. PMID:17548815

The virtual infinite capacitor

NASA Astrophysics Data System (ADS)

Yona, Guy; Weiss, George

2017-01-01

We define the virtual infinite capacitor (VIC) as a nonlinear capacitor that has the property that for an interval of the charge Q (the operating range), the voltage V remains constant. We propose a lossless approximate realisation for the VIC as a simple circuit with two controllers: a voltage controller acts fast to maintain the desired terminal voltage, while a charge controller acts more slowly and maintains the charge Q in the desired operating range by influencing the incoming current. The VIC is useful as a filter capacitor for various applications, for example, power factor compensators (PFC), as we describe. In spite of using small capacitors, the VIC can replace a very large capacitor in applications that do not require substantial energy storage. We give simulation results for a PFC working in critical conduction mode with a VIC for output voltage filtering.

Adhesive curing through low-voltage activation

PubMed Central

Ping, Jianfeng; Gao, Feng; Chen, Jian Lin; Webster, Richard D.; Steele, Terry W. J.

2015-01-01

Instant curing adhesives typically fall within three categories, being activated by either light (photocuring), heat (thermocuring) or chemical means. These curing strategies limit applications to specific substrates and can only be activated under certain conditions. Here we present the development of an instant curing adhesive through low-voltage activation. The electrocuring adhesive is synthesized by grafting carbene precursors on polyamidoamine dendrimers and dissolving in aqueous solvents to form viscous gels. The electrocuring adhesives are activated at −2 V versus Ag/AgCl, allowing tunable crosslinking within the dendrimer matrix and on both electrode surfaces. As the applied voltage discontinued, crosslinking immediately terminated. Thus, crosslinking initiation and propagation are observed to be voltage and time dependent, enabling tuning of both material properties and adhesive strength. The electrocuring adhesive has immediate implications in manufacturing and development of implantable bioadhesives. PMID:26282730

Temporary formation of highly conducting domain walls for non-destructive read-out of ferroelectric domain-wall resistance switching memories

NASA Astrophysics Data System (ADS)

Jiang, Jun; Bai, Zi Long; Chen, Zhi Hui; He, Long; Zhang, David Wei; Zhang, Qing Hua; Shi, Jin An; Park, Min Hyuk; Scott, James F.; Hwang, Cheol Seong; Jiang, An Quan

2018-01-01

Erasable conductive domain walls in insulating ferroelectric thin films can be used for non-destructive electrical read-out of the polarization states in ferroelectric memories. Still, the domain-wall currents extracted by these devices have not yet reached the intensity and stability required to drive read-out circuits operating at high speeds. This study demonstrated non-destructive read-out of digital data stored using specific domain-wall configurations in epitaxial BiFeO3 thin films formed in mesa-geometry structures. Partially switched domains, which enable the formation of conductive walls during the read operation, spontaneously retract when the read voltage is removed, reducing the accumulation of mobile defects at the domain walls and potentially improving the device stability. Three-terminal memory devices produced 14 nA read currents at an operating voltage of 5 V, and operated up to T = 85 °C. The gap length can also be smaller than the film thickness, allowing the realization of ferroelectric memories with device dimensions far below 100 nm.

Twin lead ballistic conductor based on nanoribbon edge transport

NASA Astrophysics Data System (ADS)

Konôpka, Martin; Dieška, Peter

2018-03-01

If a device like a graphene nanoribbon (GNR) has all its four corners attached to electric current leads, the device becomes a quantum junction through which two electrical circuits can interact. We study such system theoretically for stationary currents. The 4-point energy-dependent conductance matrix of the nanostructure and the classical resistors in the circuits are parameters of the model. The two bias voltages in the circuits are the control variables of the studied system while the electrochemical potentials at the device's terminals are non-trivially dependent on the voltages. For the special case of the linear-response regime analytical formulae for the operation of the coupled quantum-classical device are derived and applied. For higher bias voltages numerical solutions are obtained. The effects of non-equilibrium Fermi levels are captured using a recursive algorithm in which self-consistency between the electrochemical potentials and the currents is reached within few iterations. The developed approach allows to study scenarios ranging from independent circuits to strongly coupled ones. For the chosen model of the GNR with highly conductive zigzag edges we determine the regime in which the single device carries two almost independent currents.

Reversible Negative Resistive Switching in an Individual Fe@Al2O3 Hybrid Nanotube for Nonvolatile Memory.

PubMed

Ye, Yalong; Zhao, Jie; Xiao, Li; Cheng, Baochang; Xiao, Yanhe; Lei, Shuijin

2018-06-06

Hybrid nanostructures can show enormous potential in different areas because of their unique structural configurations. Herein, Fe@Al 2 O 3 hybrid nanotubes are constructed via a homogeneous coprecipitation method followed by subsequent annealing in a reducing atmosphere. The introduction of zero band gap Fe nanocrystals in the wall of ultrawide band gap Al 2 O 3 insulator nanotubes results in the formation of charge trap centers, and correspondingly a single hybrid nanotube-based two-terminal device can show reversible negative resistive switching (RS) characteristics with symmetrical negative differential resistance (NDR) at relatively high operation bias voltages. At a large bias voltage, holes and electrons can be injected into traps at two ends from electrodes, respectively, and then captured. The bias voltage dependence of asymmetrical filling of charges can lead to a reversible variation of built-in electromotive force, and therefore the symmetrical negative RS with NDR arises from two reversible back-to-back series bipolar RS. At a low readout voltage, the single Fe@Al 2 O 3 hybrid nanotube can show an excellent nonvolatile memory feature with a relatively large switching ratio of ∼30. The bias-governed reversible negative RS with superior stability, reversibility, nondestructive readout, and remarkable cycle performance makes it a potential candidate in next-generation erasable nonvolatile resistive random access memories.

Triple Hybrid Energy Harvesting Interface Electronics

NASA Astrophysics Data System (ADS)

Uluşan, H.; Chamanian, S.; Pathirana, W. M. P. R.; Zorlu, Ö.; Muhtaroğlu, A.; Külah, H.

2016-11-01

This study presents a novel triple hybrid system that combines simultaneously generated power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters for a relatively high power supply capability. In the proposed solution each harvesting source utilizes a distinct power management circuit that generates a DC voltage suitable for combining the three parallel supplies. The circuits are designed and implemented in 180 nm standard CMOS technology, and are terminated with a schottky diode to avoid reverse current flow. The harvested AC signal from the EM harvester is rectified with a self-powered AC-DC doubler, which utilizes active diode structures to minimize the forward- bias voltage drop. The PZT interface electronics utilizes a negative voltage converter as the first stage, followed by synchronous power extraction and DC-to-DC conversion through internal switches, and an external inductor. The ultra-low voltage DC power harvested by the TE generator is stepped up through a charge-pump driven by an LC oscillator with fully- integrated center-tapped differential inductors. Test results indicate that hybrid energy harvesting circuit provides more than 1 V output for load resistances higher than 100 kΩ (10 μW) where the stand-alone harvesting circuits are not able to reach 1 V output. This is the first hybrid harvester circuit that simultaneously extracts energy from three independent sources, and delivers a single DC output.

Scintillation Breakdowns in Chip Tantalum Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander

2008-01-01

Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often considered as nuisance rather than a failure. Scintillation breakdowns likely do not affect failures of parts under surge current conditions, and so-called "proofing" of tantalum chip capacitors, which is a controllable exposure of the part after soldering to voltages slightly higher than the operating voltage to verify that possible scintillations are self-healed, has been shown to improve the quality of the parts. However, no in-depth studies of the effect of scintillations on reliability of tantalum capacitors have been performed so far. KEMET is using scintillation breakdown testing as a tool for assessing process improvements and to compare quality of different manufacturing lots. Nevertheless, the relationship between failures and scintillation breakdowns is not clear, and this test is not considered as suitable for lot acceptance testing. In this work, scintillation breakdowns in different military-graded and commercial tantalum capacitors were characterized and related to the rated voltages and to life test failures. A model for assessment of times to failure, based on distributions of breakdown voltages, and accelerating factors of life testing are discussed.

Electrophysiology of pumpkin seeds: Memristors in vivo

PubMed Central

Volkov, Alexander G.; Nyasani, Eunice K.; Tuckett, Clayton; Greeman, Esther A.; Markin, Vladislav S.

2016-01-01

ABSTRACT Leon Chua, the discoverer of a memristor, theoretically predicted that voltage gated ion channels can be memristors. We recently found memristors in different plants such as the Venus flytrap, Mimosa pudica, Aloe vera, apple fruits, and in potato tubers. There are no publications in literature about the existence of memristors in seeds. The goal of this work was to discover if pumpkin seeds might have memristors. We selected Cucurbita pepo L., cv. Cinderella, Cucurbita maxima L. cv Warty Goblin, and Cucurbita maxima L., cv. Jarrahdale seeds for this analysis. In these seeds, we found the presence of resistors with memory. The analysis was based on cyclic voltammetry where a memristor should manifest itself as a nonlinear two-terminal electrical element, which exhibits a pinched hysteresis loop on a current-voltage plane for any bipolar cyclic voltage input signal. Dry dormant pumpkin seeds have very high electrical resistance without memristive properties. The electrostimulation by bipolar sinusoidal or triangular periodic waves induces electrical responses in imbibed pumpkin seeds with fingerprints of memristors. Tetraethylammonium chloride, an inhibitor of voltage gated K+ channels, transforms a memristor to a resistor in pumpkin seeds. NPPB (5-Nitro-2-(3-phenylpropylamino)benzoic acid) inhibits the memristive properties of imbibed pumpkin seeds. The discovery of memristors in pumpkin seeds creates a new direction in the understanding of electrophysiological phenomena in seeds. PMID:26926652

Structures of closed and open states of a voltage-gated sodium channel

PubMed Central

Lenaeus, Michael J.; Gamal El-Din, Tamer M.; Ramanadane, Karthik; Pomès, Régis; Zheng, Ning; Catterall, William A.

2017-01-01

Bacterial voltage-gated sodium channels (BacNavs) serve as models of their vertebrate counterparts. BacNavs contain conserved voltage-sensing and pore-forming domains, but they are homotetramers of four identical subunits, rather than pseudotetramers of four homologous domains. Here, we present structures of two NaVAb mutants that capture tightly closed and open states at a resolution of 2.8–3.2 Å. Introduction of two humanizing mutations in the S6 segment (NaVAb/FY: T206F and V213Y) generates a persistently closed form of the activation gate in which the intracellular ends of the four S6 segments are drawn tightly together to block ion permeation completely. This construct also revealed the complete structure of the four-helix bundle that forms the C-terminal domain. In contrast, truncation of the C-terminal 40 residues in NavAb/1–226 captures the activation gate in an open conformation, revealing the open state of a BacNav with intact voltage sensors. Comparing these structures illustrates the full range of motion of the activation gate, from closed with its orifice fully occluded to open with an orifice of ∼10 Å. Molecular dynamics and free-energy simulations confirm designation of NaVAb/1–226 as an open state that allows permeation of hydrated Na+, and these results also support a hydrophobic gating mechanism for control of ion permeation. These two structures allow completion of a closed–open–inactivated conformational cycle in a single voltage-gated sodium channel and give insight into the structural basis for state-dependent binding of sodium channel-blocking drugs. PMID:28348242

Functional characterization of Kv11.1 (hERG) potassium channels split in the voltage-sensing domain.

PubMed

de la Peña, Pilar; Domínguez, Pedro; Barros, Francisco

2018-03-23

Voltage-dependent KCNH family potassium channel functionality can be reconstructed using non-covalently linked voltage-sensing domain (VSD) and pore modules (split channels). However, the necessity of a covalent continuity for channel function has not been evaluated at other points within the two functionally independent channel modules. We find here that by cutting Kv11.1 (hERG, KCNH2) channels at the different loops linking the transmembrane spans of the channel core, not only channels split at the S4-S5 linker level, but also those split at the intracellular S2-S3 and the extracellular S3-S4 loops, yield fully functional channel proteins. Our data indicate that albeit less markedly, channels split after residue 482 in the S2-S3 linker resemble the uncoupled gating phenotype of those split at the C-terminal end of the VSD S4 transmembrane segment. Channels split after residues 514 and 518 in the S3-S4 linker show gating characteristics similar to those of the continuous wild-type channel. However, breaking the covalent link at this level strongly accelerates the voltage-dependent accessibility of a membrane impermeable methanethiosulfonate reagent to an engineered cysteine at the N-terminal region of the S4 transmembrane helix. Thus, besides that of the S4-S5 linker, structural integrity of the intracellular S2-S3 linker seems to constitute an important factor for proper transduction of VSD rearrangements to opening and closing the cytoplasmic gate. Furthermore, our data suggest that the short and probably rigid characteristics of the extracellular S3-S4 linker are not an essential component of the Kv11.1 voltage sensing machinery.

Electrostatic quadrupole array for focusing parallel beams of charged particles

DOEpatents

Brodowski, John

1982-11-23

An array of electrostatic quadrupoles, capable of providing strong electrostatic focusing simultaneously on multiple beams, is easily fabricated from a single array element comprising a support rod and multiple electrodes spaced at intervals along the rod. The rods are secured to four terminals which are isolated by only four insulators. This structure requires bias voltage to be supplied to only two terminals and eliminates the need for individual electrode bias and insulators, as well as increases life by eliminating beam plating of insulators.

Resonant optical device with a microheater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lentine, Anthony L.; DeRose, Christopher

2017-04-04

A resonant photonic device is provided. The device comprises an optical waveguiding element, such as an optical resonator, that includes a diode junction region, two signal terminals configured to apply a bias voltage across the junction region, and a heater laterally separated from the optical waveguiding element. A semiconductor electrical barrier element is juxtaposed to the heater. A metallic strip is electrically and thermally connected at one end to a signal terminal of the optical waveguiding element and thermally connected at another end to the barrier element.

Accurate reconstruction of the jV-characteristic of organic solar cells from measurements of the external quantum efficiency

NASA Astrophysics Data System (ADS)

Meyer, Toni; Körner, Christian; Vandewal, Koen; Leo, Karl

2018-04-01

In two terminal tandem solar cells, the current density - voltage (jV) characteristic of the individual subcells is typically not directly measurable, but often required for a rigorous device characterization. In this work, we reconstruct the jV-characteristic of organic solar cells from measurements of the external quantum efficiency under applied bias voltages and illumination. We show that it is necessary to perform a bias irradiance variation at each voltage and subsequently conduct a mathematical correction of the differential to the absolute external quantum efficiency to obtain an accurate jV-characteristic. Furthermore, we show that measuring the external quantum efficiency as a function of voltage for a single bias irradiance of 0.36 AM1.5g equivalent sun provides a good approximation of the photocurrent density over voltage curve. The method is tested on a selection of efficient, common single-junctions. The obtained conclusions can easily be transferred to multi-junction devices with serially connected subcells.

Regenerative switching CMOS system

DOEpatents

Welch, James D.

1998-01-01

Complementary Metal Oxide Semiconductor (CMOS) Schottky barrier Field Effect Transistor systems, which are a seriesed combination of N and P-Channel MOSFETS, in which Source Schottky barrier junctions of the N and P-Channel Schottky barrier MOSFETS are electically interconnected, (rather than the Drains as in conventional diffused junction CMOS), which Schottky barrier MOSFET system demonstrates Regenerative Inverting Switching Characteristics in use are disclosed. Both the N and P-Channel Schottky barrier MOSFET devices are unique in that they provide operational Drain Current vs. Drain to Source voltage as a function of Gate voltage only where the polarities of the Drain voltage and Gate voltage are opposite, referenced to the Source as a common terminal, and where the polarity of the voltage applied to the Gate is appropriate to cause Channel inversion. Experimentally derived results which demonstrate and verify the operation of N and P-Channel Schottky barrier MOSFETS actually fabricated on P and N-type Silicon respectively, by a common procedure using vacuum deposited Chromium as a Schottky barrier forming metal, are also provided.

Regenerative switching CMOS system

DOEpatents

Welch, J.D.

1998-06-02

Complementary Metal Oxide Semiconductor (CMOS) Schottky barrier Field Effect Transistor systems, which are a series combination of N and P-Channel MOSFETS, in which Source Schottky barrier junctions of the N and P-Channel Schottky barrier MOSFETS are electrically interconnected, (rather than the Drains as in conventional diffused junction CMOS), which Schottky barrier MOSFET system demonstrates Regenerative Inverting Switching Characteristics in use are disclosed. Both the N and P-Channel Schottky barrier MOSFET devices are unique in that they provide operational Drain Current vs. Drain to Source voltage as a function of Gate voltage only where the polarities of the Drain voltage and Gate voltage are opposite, referenced to the Source as a common terminal, and where the polarity of the voltage applied to the Gate is appropriate to cause Channel inversion. Experimentally derived results which demonstrate and verify the operation of N and P-Channel Schottky barrier MOSFETS actually fabricated on P and N-type Silicon respectively, by a common procedure using vacuum deposited Chromium as a Schottky barrier forming metal, are also provided. 14 figs.

Bipolar Nickel-Metal Hydride Battery Development Project

NASA Technical Reports Server (NTRS)

Cole, John H.

1999-01-01

This paper reviews the development of the Electro Energy, Inc.'s bipolar nickel metal hydride battery. The advantages of the design are that each cell is individually sealed, and that there are no external cell terminals, no electrode current collectors, it is compatible with plastic bonded electrodes, adaptable to heat transfer fins, scalable to large area, capacity and high voltage. The design will allow for automated flexible manufacturing, improved energy and power density and lower cost. The development and testing of the battery's component are described. Graphic presentation of the results of many of the tests are included.

Precessional switching of a perpendicular anisotropy magneto-tunneling junction without a magnetic field

NASA Astrophysics Data System (ADS)

Drobitch, Justine L.; Ahsanul Abeed, Md; Bandyopadhyay, Supriyo

2017-10-01

We describe an approach to implement precessional switching of a perpendicular-magnetic-anisotropy magneto-tunneling-junction (p-MTJ) without using any magnetic field. The switching is accomplished with voltage-controlled-magnetic-anisotropy (VCMA), spin transfer torque (STT) and mechanical strain. The soft layer of the p-MTJ is magnetostrictive and the strain acts as an effective in-plane magnetic field around which the magnetization of the soft layer precesses to complete a flip. A two-terminal energy-efficient p-MTJ based memory cell, that is compatible with crossbar architecture and high cell density, is designed.

Challenging developments in three decades of accelerator mass spectrometry at ETH: from large particle accelerators to table size instruments.

PubMed

Suter, Martin

2010-01-01

Accelerator mass spectrometry (AMS) was invented for the detection of radiocarbon at natural isotopic concentrations (10(-12) to 10(-15)) more than 30 years ago. Meanwhile this method has also been applied for the analysis of many other long-lived radioisotopes, which are found at very low concentrations. The first investigations were made at large tandem accelerators originally built for nuclear physics research and operating at voltages of 6-12 MV. Today dedicated instruments are mostly used for AMS, which are optimized for associated applications. In the past 15 years, a new generation of much smaller instruments has been developed. For many years it was believed that accelerators with voltages of 2 MV or higher are needed to eliminate the molecular interferences. At these energies the ions are predominantly stripped to charge state 3+, thereby removing the binding electrons of the molecules. In contrast, the new compact facilities use 1+ or 2+ ions. In this case the molecular destruction process is based on molecule-atom collisions in the gas cell. The cross sections for this destruction are sufficiently large that the intensity of molecular components such as (12)CH(2) and (13)CH can be reduced by 10 orders of magnitude. These new facilities can be built much smaller due to the lower energies. Universal instruments providing analysis for many isotopes over the whole range of periodic table have a space requirement of about 4 x 6 m(2); dedicated radiocarbon facilities based on a 200 kV accelerator have a footprint of about 2.5 x 3 m(2). This smallest category of instruments use special technologies: The high voltage terminal with the gas stripper canal is vacuum insulated and the gas is pumped to ground potential through a ceramic pipe. A conventional 200 kV power supply provides the terminal voltage from outside. A review of this new generation of compact AMS facilities is given. Design considerations and performance of these new instruments will be presented. With these developments, new AMS instruments are not much larger than conventional mass spectrometers, allowing a significant reduction in cost.

Maturation of Cerebellar Purkinje Cell Population Activity during Postnatal Refinement of Climbing Fiber Network.

PubMed

Good, Jean-Marc; Mahoney, Michael; Miyazaki, Taisuke; Tanaka, Kenji F; Sakimura, Kenji; Watanabe, Masahiko; Kitamura, Kazuo; Kano, Masanobu

2017-11-21

Neural circuits undergo massive refinements during postnatal development. In the developing cerebellum, the climbing fiber (CF) to Purkinje cell (PC) network is drastically reshaped by eliminating early-formed redundant CF to PC synapses. To investigate the impact of CF network refinement on PC population activity during postnatal development, we monitored spontaneous CF responses in neighboring PCs and the activity of populations of nearby CF terminals using in vivo two-photon calcium imaging. Population activity is highly synchronized in newborn mice, and the degree of synchrony gradually declines during the first postnatal week in PCs and, to a lesser extent, in CF terminals. Knockout mice lacking P/Q-type voltage-gated calcium channel or glutamate receptor δ2, in which CF network refinement is severely impaired, exhibit an abnormally high level of synchrony in PC population activity. These results suggest that CF network refinement is a structural basis for developmental desynchronization and maturation of PC population activity. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection

DOEpatents

Wood, Charles B.

1992-01-01

A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities.

Instrumentation for measurement of aircraft noise and sonic boom

NASA Technical Reports Server (NTRS)

Zuckerwar, A. J. (Inventor)

1975-01-01

A jet aircraft noise and sonic boom measuring device which converts sound pressure into electric current is described. An electric current proportional to the sound pressure level at a condenser microphone is produced and transmitted over a cable, amplified by a zero drive amplifier and recorded on magnetic tape. The converter is comprised of a local oscillator, a dual-gate field-effect transistor (FET) mixer and a voltage regulator/impedance translator. A carrier voltage that is applied to one of the gates of the FET mixer is generated by the local oscillator. The microphone signal is mixed with the carrier to produce an electrical current at the frequency of vibration of the microphone diaphragm by the FET mixer. The voltage of the local oscillator and mixer stages is regulated, the carrier at the output is eliminated, and a low output impedance at the cable terminals is provided by the voltage regulator/impedance translator.

Fiber-optic voltage sensor with cladded fiber and evanescent wave variation detection

DOEpatents

Wood, C.B.

1992-12-15

A fiber optic voltage sensor is described which includes a source of light, a reference fiber for receiving a known percentage of the light and an electrostrictive element having terminals across which is applied, a voltage to be measured. The electrostrictive element is responsive to the applied voltage to assume an altered physical state. A measuring fiber also receives a known percentage of light from the light source and is secured about the electrostrictive element. The measuring fiber is provided with a cladding and exhibits an evanescent wave in the cladding. The measuring fiber has a known length which is altered when the electrostrictive element assumes its altered physical state. A differential sensor is provided which senses the intensity of light in both the reference fiber and the measuring fiber and provides an output indicative of the difference between the intensities. 3 figs.

Resonant tunneling based graphene quantum dot memristors.

PubMed

Pan, Xuan; Skafidas, Efstratios

2016-12-08

In this paper, we model two-terminal all graphene quantum dot (GQD) based resistor-type memory devices (memristors). The resistive switching is achieved by resonant electron tunneling. We show that parallel GQDs can be used to create multi-state memory circuits. The number of states can be optimised with additional voltage sources, whilst the noise margin for each state can be controlled by appropriately choosing the branch resistance. A three-terminal GQD device configuration is also studied. The addition of an isolated gate terminal can be used to add further or modify the states of the memory device. The proposed devices provide a promising route towards volatile memory devices utilizing only atomically thin two-dimensional graphene.

Digitally controlled distributed phase shifter

DOEpatents

Hietala, V.M.; Kravitz, S.H.; Vawter, G.A.

1993-08-17

A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one or two discrete bias voltages. The application of the discrete bias voltages changes the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

Digitally controlled distributed phase shifter

DOEpatents

Hietala, Vincent M.; Kravitz, Stanley H.; Vawter, Gregory A.

1993-01-01

A digitally controlled distributed phase shifter is comprised of N phase shifters. Digital control is achieved by using N binary length-weighted electrodes located on the top surface of a waveguide. A control terminal is attached to each electrode thereby allowing the application of a control signal. The control signal is either one or two discrete bias voltages. The application of the discrete bias voltages changes the modal index of a portion of the waveguide that corresponds to a length of the electrode to which the bias voltage is applied, thereby causing the phase to change through the underlying portion of the waveguide. The digitally controlled distributed phase shift network has a total phase shift comprised of the sum of the individual phase shifters.

ELECTRONIC INTEGRATING CIRCUIT

DOEpatents

Englemann, R.H.

1963-08-20

An electronic integrating circuit using a transistor with a capacitor connected between the emitter and collector through which the capacitor discharges at a rate proportional to the input current at the base is described. Means are provided for biasing the base with an operating bias and for applying a voltage pulse to the capacitor for charging to an initial voltage. A current dividing diode is connected between the base and emitter of the transistor, and signal input terminal means are coupled to the juncture of the capacitor and emitter and to the base of the transistor. At the end of the integration period, the residual voltage on said capacitor is less by an amount proportional to the integral of the input signal. Either continuous or intermittent periods of integration are provided. (AEC)

Cryogenic Evaluation of an Advanced DC/DC Converter Module for Deep Space Applications

NASA Technical Reports Server (NTRS)

Elbuluk, Malik E.; Hammoud, Ahmad; Gerber, Scott S.; Patterson, Richard

2003-01-01

DC/DC converters are widely used in power management, conditioning, and control of space power systems. Deep space applications require electronics that withstand cryogenic temperature and meet a stringent radiation tolerance. In this work, the performance of an advanced, radiation-hardened (rad-hard) commercial DC/DC converter module was investigated at cryogenic temperatures. The converter was investigated in terms of its steady state and dynamic operations. The output voltage regulation, efficiency, terminal current ripple characteristics, and output voltage response to load changes were determined in the temperature range of 20 to -140 C. These parameters were obtained at various load levels and at different input voltages. The experimental procedures along with the results obtained on the investigated converter are presented and discussed.

Induction motor speed control using varied duty cycle terminal voltage via PI controller

NASA Astrophysics Data System (ADS)

Azwin, A.; Ahmed, S.

2018-03-01

This paper deals with the PI speed controller for the three-phase induction motor using PWM technique. The PWM generated signal is utilized for voltage source inverter with an optimal duty cycle on a simplified induction motor model. A control algorithm for generating PWM control signal is developed. Obtained results shows that the steady state error and overshoot of the developed system is in the limit under different speed and load condition. The robustness of the control performance would be potential for induction motor performance improvement.

Analyzing Internal Fragmentation of Electrosprayed Ubiquitin Ions During Beam-Type Collisional Dissociation

NASA Astrophysics Data System (ADS)

Durbin, Kenneth R.; Skinner, Owen S.; Fellers, Ryan T.; Kelleher, Neil L.

2015-05-01

Gaseous fragmentation of intact proteins is multifaceted and can be unpredictable by current theories in the field. Contributing to the complexity is the multitude of precursor ion states and fragmentation channels. Terminal fragment ions can be re-fragmented, yielding product ions containing neither terminus, termed internal fragment ions. In an effort to better understand and capitalize upon this fragmentation process, we collisionally dissociated the high (13+), middle (10+), and low (7+) charge states of electrosprayed ubiquitin ions. Both terminal and internal fragmentation processes were quantified through step-wise increases of voltage potential in the collision cell. An isotope fitting algorithm matched observed product ions to theoretical terminal and internal fragment ions. At optimal energies for internal fragmentation of the 10+, nearly 200 internal fragments were observed; on average each of the 76 residues in ubiquitin was covered by 24.1 internal fragments. A pertinent finding was that formation of internal ions occurs at similar energy thresholds as terminal b- and y-ion types in beam-type activation. This large amount of internal fragmentation is frequently overlooked during top-down mass spectrometry. As such, we present several new approaches to visualize internal fragments through modified graphical fragment maps. With the presented advances of internal fragment ion accounting and visualization, the total percentage of matched fragment ions increased from approximately 40% to over 75% in a typical beam-type MS/MS spectrum. These sequence coverage improvements offer greater characterization potential for whole proteins with no needed experimental changes and could be of large benefit for future high-throughput intact protein analysis.

Measuring the upset of CMOS and TTL due to HPM-signals

NASA Astrophysics Data System (ADS)

Esser, N.; Smailus, B.

2004-05-01

To measure the performance of electronic components when stressed by High Power Microwave signals a setup was designed and tested which allows a well-defined voltage signal to enter the component during normal operation, and to discriminate its effect on the component. The microwave signal is fed to the outside conductor of a coaxial cable and couples into the inner signal line connected to the device under test (DUT). The disturbing HF-signal is transferred almost independent from frequency to maintain the pulse shape in the time domain. The configuration designed to perform a TEM-coupling within a 50 Ohm system prevents the secondary system from feeding back to the primary system and, due to the geometrical parameters chosen, the coupling efficiency is as high as 50-90%. Linear dimensions and terminations applied allow for pulses up to a width of 12ns and up to a voltage level of 4-5 kV on the outside conductor. These pulse parameters proved to be sufficient to upset the DUTs tested so far. In more than 400 measurements a rectangular pulse of increasing voltage level was applied to different types of CMOS and TTL until the individual DUT was damaged. As well the pulse width (3, 6 or 12 ns) and its polarity were varied in single-shot or repetitive-shot experiments (500 shots per voltage at a repetition rate of 3 Hz). The state of the DUT was continuously monitored by measuring both the current of the DUT circuit and that of the oscillator providing the operating signal for the DUT. The results show a very good reproducibility within a set of identical samples, remarkable differences between manufacturers and lower thresholds for repetitive testing, which indicates a memory effect of the DUT to exist for voltage levels significantly below the single-shot threshold.

High Voltage, Sub Nanosecond Feedthrough Design for Liquid Breakdown Studies

NASA Astrophysics Data System (ADS)

Cevallos, Michael; Dickens, James; Neuber, Andreas; Krompholz, Herman

2002-12-01

Experiments in self-breakdown mode and pulsed breakdown at high over-voltages in standard electrode geometries are performed for liquids to gain a better understanding of their fundamental breakdown physics. Different liquids of interest include liquids such as super-cooled liquid nitrogen, oils, glycerols and water. A typical setup employs a discharge chamber with a cable discharge into a coaxial system with axial discharge, and a load line to simulate a matched terminating impedance, thus providing a sub-nanosecond response. This study is focused on the feed-through design of the coaxial cable into this type of discharge chamber, with the feed-through being the critical element with respect to maximum hold-off voltage. Diverse feedthroughs were designed and simulated using Maxwell 3-D Field Simulator Version 5. Several geometrically shaped feed-through transitions were simulated, including linearly and exponentially tapered, to minimize electrostatic fields, thus ensuring that the discharge occurs in the volume of interest and not between the inner and outer conductor at the transition from the insulation of the coaxial cable to the liquid. All feedthroughs are designed to match the incoming impedance of the coaxial cable. The size of the feedthroughs will vary from liquid to liquid in order to match the coaxial cable impedance of 50Ω. The discharge chamber has two main ports where the feed-through will enter the chamber. Each feed-through is built through a flange that covers the two main ports. This allows the use of the same discharge chamber for various liquids by changing the flanges on the main ports to match the particular liquid. The feedthroughs were designed and built to withstand voltages of up to 200 kV. The feedthroughs are also fitted with transmission line type current sensors and capacitive voltage dividers with fast amplifiers/attenuators in order to attain a complete range of information from amplitudes of 0.1mA to 1 kA with a temporal resolution of 300 ps.

Timing and efficacy of Ca2+ channel activation in hippocampal mossy fiber boutons.

PubMed

Bischofberger, Josef; Geiger, Jörg R P; Jonas, Peter

2002-12-15

The presynaptic Ca2+ signal is a key determinant of transmitter release at chemical synapses. In cortical synaptic terminals, however, little is known about the kinetic properties of the presynaptic Ca2+ channels. To investigate the timing and magnitude of the presynaptic Ca2+ inflow, we performed whole-cell patch-clamp recordings from mossy fiber boutons (MFBs) in rat hippocampus. MFBs showed large high-voltage-activated Ca(2+) currents, with a maximal amplitude of approximately 100 pA at a membrane potential of 0 mV. Both activation and deactivation were fast, with time constants in the submillisecond range at a temperature of approximately 23 degrees C. An MFB action potential (AP) applied as a voltage-clamp command evoked a transient Ca2+ current with an average amplitude of approximately 170 pA and a half-duration of 580 microsec. A prepulse to +40 mV had only minimal effects on the AP-evoked Ca2+ current, indicating that presynaptic APs open the voltage-gated Ca2+ channels very effectively. On the basis of the experimental data, we developed a kinetic model with four closed states and one open state, linked by voltage-dependent rate constants. Simulations of the Ca2+ current could reproduce the experimental data, including the large amplitude and rapid time course of the current evoked by MFB APs. Furthermore, the simulations indicate that the shape of the presynaptic AP and the gating kinetics of the Ca2+ channels are tuned to produce a maximal Ca2+ influx during a minimal period of time. The precise timing and high efficacy of Ca2+ channel activation at this cortical glutamatergic synapse may be important for synchronous transmitter release and temporal information processing.

Membrane potential bistability in nonexcitable cells as described by inward and outward voltage-gated ion channels.

PubMed

Cervera, Javier; Alcaraz, Antonio; Mafe, Salvador

2014-10-30

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 the hyperpolarized and depolarized values of the membrane potential, as well as the possibility to obtain a bistability behavior, using simplified models for the ion channels that regulate this potential. The bistability regions, which are defined in the multidimensional state space determining the cell state, can be relevant for the understanding of the different model cell states and the transitions between them, which are triggered by changes in the external environment.

Development of 50kV air-core transformer for electron gun static power source of 3MeV DC accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dewangan, S.; Bakhtsingh, R.I.; Rajan, R.N.

A 3 MeV, 10 mA DC Electron Beam Accelerator based on the capacitively coupled parallel-fed voltage multiplier in 6 kg/cm{sup 2} SF{sub 6} gas environment is under commissioning at Electron Beam Centre, Kharghar, Navi Mumbai. Electron Gun is situated at -3 MV terminal which requires a constant power for its anode and filament. Gun power source has been derived by suitably coupling the ac components present in the HV Multiplier column. An aircore step down transformer rated for 50kV/600V/120kHz floating at 3 MV to extract the required power for electron gun from high voltage column has been developed. The transformermore » has been operated for 7 kW, 1 MeV of electron beam in 6 kg/cm{sup 2} nitrogen gas environment. The paper describes briefly about the design aspects and test results. (author)« less

GaInP2/GaAs tandem cells for space applications

NASA Technical Reports Server (NTRS)

Olson, J. M.; Kurtz, S. R.; Kibbler, A. E.; Bertness, K. A.; Friedman, D. J.

1991-01-01

The monolithic, tunnel-junction-interconnected tandem combination of a GaInP2 top cell and a GaAs bottom cell has achieved a one-sun, AM1.5 efficiency of 27.3 percent. With proper design of the top cell, air mass zero (AM0) efficiencies greater than 25 percent are possible. A description and the advantages of this device for space applications are presented and discussed. The advantages include high-voltage, low-current, two-terminal operation for simple panel fabrication, and high conversion efficiency with low-temperature coefficient. Also, because the active regions of the device are Al-free, the growth of high efficiency devices is not affected by trace levels of O2 or H2O in the MOCVD growth system.

A transparent electrochromic metal-insulator switching device with three-terminal transistor geometry

NASA Astrophysics Data System (ADS)

Katase, Takayoshi; Onozato, Takaki; Hirono, Misako; Mizuno, Taku; Ohta, Hiromichi

2016-05-01

Proton and hydroxyl ion play an essential role for tuning functionality of oxides because their electronic state can be controlled by modifying oxygen off-stoichiometry and/or protonation. Tungsten trioxide (WO3), a well-known electrochromic (EC) material for smart window, is a wide bandgap insulator, whereas it becomes a metallic conductor HxWO3 by protonation. Although one can utilize electrochromism together with metal-insulator (MI) switching for one device, such EC-MI switching cannot be utilized in current EC devices because of their two-terminal structure with parallel-plate configuration. Here we demonstrate a transparent EC-MI switchable device with three-terminal TFT-type structure using amorphous (a-) WO3 channel layer, which was fabricated on glass substrate at room temperature. We used water-infiltrated nano-porous glass, CAN (calcium aluminate with nano-pores), as a liquid-leakage-free solid gate insulator. At virgin state, the device was fully transparent in the visible-light region. For positive gate voltage, the active channel became dark blue, and electrical resistivity of the a-WO3 layer drastically decreased with protonation. For negative gate voltage, deprotonation occurred and the active channel returned to transparent insulator. Good cycleability of the present transparent EC-MI switching device would have potential for the development of advanced smart windows.

Capillary zone electrophoresis determination of aniline and pyridine in sewage samples using transient isotachophoresis with a system-induced terminator.

PubMed

Hattori, Takanari; Okamura, Hideo; Asaoka, Satoshi; Fukushi, Keiichi

2017-08-18

Transient isotachophoresis (tITP) with a system-induced terminator (SIT) was developed for capillary zone electrophoresis (CZE) determination of aniline (An + ) and pyridine (Py + ) in sewage samples. After sample injection, a water vial was set at the sample-inlet side. Then voltage was applied to generate a system-induced terminator (H + ). Experiments and simulations revealed a concentration effect by tITP with an SIT: background electrolyte (BGE) - 100mM acetic acid (AcOH) and 50mM NaOH (pH 4.6); detection wavelength - 200nm for An + and 254nm for Py + ; vacuum injection period - 15s (190nL); SIT generation - 10kV applied for 80s with the sample inlet side anode; separation voltage - 20kV with the sample inlet side anode. The limits of detection (LODs, S/N=3) of An + and Py + respectively reached 10 and 42μg/L, with good repeatability (peak area RSDs≤6.9%) and calibration graph linearity (R 2 =0.9997). The proposed method was applied for determination of An + and Py + in sewage samples. Recoveries of An + (0.50mg/L) and Py + (2.0mg/L) in spiked sewage samples were 94-104%. Copyright © 2017 Elsevier B.V. All rights reserved.

Meter circuit for tuning RF amplifiers

NASA Technical Reports Server (NTRS)

Longthorne, J. E.

1973-01-01

Circuit computes and indicates efficiency of RF amplifier as inputs and other parameters are varied. Voltage drop across internal resistance of ammeter is amplified by operational amplifier and applied to one multiplier input. Other input is obtained through two resistors from positive terminal of power supply.

A dedicated AMS setup for 53Mn/60Fe at the Cologne FN tandem accelerator

NASA Astrophysics Data System (ADS)

Schiffer, M.; Dewald, A.; Feuerstein, C.; Altenkirch, R.; Stolz, A.; Heinze, S.

2015-10-01

Following demands for AMS measurements of medium mass isotopes, especially for 53Mn and 60Fe, we started to build a dedicated AMS setup at the Cologne FN tandem accelerator. This accelerator with a maximum terminal voltage of 10 MV can be reliably operated at a terminal voltage of 9.5 MV which corresponds to energies of 93-102 MeV for 60Fe or 53Mn beams using the 9+ or 10+ charge state. These charge states can be obtained by foil stripping with efficiencies of 30% and 20%, respectively. Energies around 100 MeV are sufficient to effectively suppress the stable isobars 60Ni and 53Cr by (dE/dx) techniques using combinations of energy degrader foils and dispersive elements like electrostatic analyzers and time of flight (TOF) systems as well as (dE/dx)E ion detectors. In this contribution we report on the actual status of the AMS setup and discuss details and expected features.

Position and Speed Control of Brushless DC Motors Using Sensorless Techniques and Application Trends

PubMed Central

Gamazo-Real, José Carlos; Vázquez-Sánchez, Ernesto; Gómez-Gil, Jaime

2010-01-01

This paper provides a technical review of position and speed sensorless methods for controlling Brushless Direct Current (BLDC) motor drives, including the background analysis using sensors, limitations and advances. The performance and reliability of BLDC motor drivers have been improved because the conventional control and sensing techniques have been improved through sensorless technology. Then, in this paper sensorless advances are reviewed and recent developments in this area are introduced with their inherent advantages and drawbacks, including the analysis of practical implementation issues and applications. The study includes a deep overview of state-of-the-art back-EMF sensing methods, which includes Terminal Voltage Sensing, Third Harmonic Voltage Integration, Terminal Current Sensing, Back-EMF Integration and PWM strategies. Also, the most relevant techniques based on estimation and models are briefly analysed, such as Sliding-mode Observer, Extended Kalman Filter, Model Reference Adaptive System, Adaptive observers (Full-order and Pseudoreduced-order) and Artificial Neural Networks. PMID:22163582

Patterned Ferroelectric Films for Tunable Microwave Devices

NASA Technical Reports Server (NTRS)

Miranda, Felix A.; Mueller, Carl H.

2008-01-01

Tunable microwave devices based on metal terminals connected by thin ferroelectric films can be made to perform better by patterning the films to include suitably dimensioned, positioned, and oriented constrictions. The patterns can be formed during fabrication by means of selective etching processes. If the width of the ferroelectric film in such a device is reduced at one or more locations, then both the microwave field and any applied DC bias (tuning) electric field become concentrated at those locations. The magnitudes of both the permittivity and the dielectric loss of a ferroelectric material are reduced by application of a DC field. Because the concentration of the DC field in the constriction(s) magnifies the permittivity- and loss-reducing effects of the applied DC voltage, the permittivity and dielectric loss in the constriction(s) are smaller in the constriction(s) than they are in the wider parts of the ferroelectric film. Furthermore, inasmuch as displacement current must flow through either the constriction(s) or the low-loss dielectric substrate, the net effect of the constriction(s) is equivalent to that of incorporating one or more low-loss, low-permittivity region(s) in series with the high-loss, high-permittivity regions. In a series circuit, the properties of the low-capacitance series element (in this case, the constriction) dominate the overall performance. Concomitantly, the capacitance between the metal terminals is reduced. By making the capacitance between the metal terminals small but tunable, a constriction increases the upper limit of the frequency range amenable to ferroelectric tuning. The present patterning concept is expected to be most advantageous for devices and circuits that must operate at frequencies from about 4 to about 60 GHz. A constriction can be designed such that the magnitude of the microwave electric field and the effective width of the region occupied by the microwave electric field become functions of the applied DC electric field, so that tunability is enhanced. It should even be possible to design the constriction to obtain a specific tuning-versus-voltage profile.

Preparation of Power Distribution System for High Penetration of Renewable Energy Part I. Dynamic Voltage Restorer for Voltage Regulation Pat II. Distribution Circuit Modeling and Validation

NASA Astrophysics Data System (ADS)

Khoshkbar Sadigh, Arash

Part I: Dynamic Voltage Restorer In the present power grids, voltage sags are recognized as a serious threat and a frequently occurring power-quality problem and have costly consequence such as sensitive loads tripping and production loss. Consequently, the demand for high power quality and voltage stability becomes a pressing issue. Dynamic voltage restorer (DVR), as a custom power device, is more effective and direct solutions for "restoring" the quality of voltage at its load-side terminals when the quality of voltage at its source-side terminals is disturbed. In the first part of this thesis, a DVR configuration with no need of bulky dc link capacitor or energy storage is proposed. This fact causes to reduce the size of the DVR and increase the reliability of the circuit. In addition, the proposed DVR topology is based on high-frequency isolation transformer resulting in the size reduction of transformer. The proposed DVR circuit, which is suitable for both low- and medium-voltage applications, is based on dc-ac converters connected in series to split the main dc link between the inputs of dc-ac converters. This feature makes it possible to use modular dc-ac converters and utilize low-voltage components in these converters whenever it is required to use DVR in medium-voltage application. The proposed configuration is tested under different conditions of load power factor and grid voltage harmonic. It has been shown that proposed DVR can compensate the voltage sag effectively and protect the sensitive loads. Following the proposition of the DVR topology, a fundamental voltage amplitude detection method which is applicable in both single/three-phase systems for DVR applications is proposed. The advantages of proposed method include application in distorted power grid with no need of any low-pass filter, precise and reliable detection, simple computation and implementation without using a phased locked loop and lookup table. The proposed method has been verified by simulation and experimental tests under various conditions considering all possible cases such as different amounts of voltage sag depth (VSD), different amounts of point-on-wave (POW) at which voltage sag occurs, harmonic distortion, line frequency variation, and phase jump (PJ). Furthermore, the ripple amount of fundamental voltage amplitude calculated by the proposed method and its error is analyzed considering the line frequency variation together with harmonic distortion. The best and worst detection time of proposed method were measured 1ms and 8.8ms, respectively. Finally, the proposed method has been compared with other voltage sag detection methods available in literature. Part 2: Power System Modeling for Renewable Energy Integration: As power distribution systems are evolving into more complex networks, electrical engineers have to rely on software tools to perform circuit analysis. There are dozens of powerful software tools available in the market to perform the power system studies. Although their main functions are similar, there are differences in features and formatting structures to suit specific applications. This creates challenges for transferring power system circuit models data (PSCMD) between different software and rebuilding the same circuit in the second software environment. The objective of this part of thesis is to develop a Unified Platform (UP) to facilitate transferring PSCMD among different software packages and relieve the challenges of the circuit model conversion process. UP uses a commonly available spreadsheet file with a defined format, for any home software to write data to and for any destination software to read data from, via a script-based application called PSCMD transfer application. The main considerations in developing the UP are to minimize manual intervention and import a one-line diagram into the destination software or export it from the source software, with all details to allow load flow, short circuit and other analyses. In this study, ETAP, OpenDSS, and GridLab-D are considered, and PSCMD transfer applications written in MATLAB have been developed for each of these to read the circuit model data provided in the UP spreadsheet. In order to test the developed PSCMD transfer applications, circuit model data of a test circuit and a power distribution circuit from Southern California Edison (SCE) - a utility company - both built in CYME, were exported into the spreadsheet file according to the UP format. Thereafter, circuit model data were imported successfully from the spreadsheet files into above mentioned software using the PSCMD transfer applications developed for each software. After the SCE studied circuit is transferred into OpenDSS software using the proposed UP scheme and developed application, it has been studied to investigate the impacts of large-scale solar energy penetration. The main challenge of solar energy integration into power grid is its intermittency (i.e., discontinuity of output power) nature due to cloud shading of photovoltaic panels which depends on weather conditions. In order to conduct this study, OpenDSS time-series simulation feature, which is required due to intermittency of solar energy, is utilized. In this study, the impacts of intermittency of solar energy penetration, especially high-variability points, on voltage fluctuation and operation of capacitor bank and voltage regulator is provided. In addition, the necessity to interpolate and resample unequally spaced time-series measurement data and convert them to equally spaced time-series data as well as the effect of resampling time-interval on the amount of error is discussed. Two applications are developed in Matlab to do interpolation and resampling as well as to calculate the amount of error for different resampling time-intervals to figure out the suitable resampling time-interval. Furthermore, an approach based on cumulative distribution, regarding the length for lines/cables types and the power rating for loads, is presented to prioritize which loads, lines and cables the meters should be installed at to have the most effect on model validation.

KCNE1 remodels the voltage sensor of Kv7.1 to modulate channel function.

PubMed

Wu, Dick; Pan, Hua; Delaloye, Kelli; Cui, Jianmin

2010-12-01

The KCNE1 auxiliary subunit coassembles with the Kv7.1 channel and modulates its properties to generate the cardiac I(Ks) current. Recent biophysical evidence suggests that KCNE1 interacts with the voltage-sensing domain (VSD) of Kv7.1. To investigate the mechanism of how KCNE1 affects the VSD to alter the voltage dependence of channel activation, we perturbed the VSD of Kv7.1 by mutagenesis and chemical modification in the absence and presence of KCNE1. Mutagenesis of S4 in Kv7.1 indicates that basic residues in the N-terminal half (S4-N) and C-terminal half (S4-C) of S4 are important for stabilizing the resting and activated states of the channel, respectively. KCNE1 disrupts electrostatic interactions involving S4-C, specifically with the lower conserved glutamate in S2 (Glu(170) or E2). Likewise, Trp scanning of S4 shows that mutations to a cluster of residues in S4-C eliminate current in the presence of KCNE1. In addition, KCNE1 affects S4-N by enhancing MTS accessibility to the top of the VSD. Consistent with the structure of Kv channels and previous studies on the KCNE1-Kv7.1 interaction, these results suggest that KCNE1 alters the interactions of S4 residues with the surrounding protein environment, possibly by changing the protein packing around S4, thereby affecting the voltage dependence of Kv7.1. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

High Density Memory Based on Quantum Device Technology

NASA Technical Reports Server (NTRS)

vanderWagt, Paul; Frazier, Gary; Tang, Hao

1995-01-01

We explore the feasibility of ultra-high density memory based on quantum devices. Starting from overall constraints on chip area, power consumption, access speed, and noise margin, we deduce boundaries on single cell parameters such as required operating voltage and standby current. Next, the possible role of quantum devices is examined. Since the most mature quantum device, the resonant tunneling diode (RTD) can easily be integrated vertically, it naturally leads to the issue of 3D integrated memory. We propose a novel method of addressing vertically integrated bistable two-terminal devices, such as resonant tunneling diodes (RTD) and Esaki diodes, that avoids individual physical contacts. The new concept has been demonstrated experimentally in memory cells of field effect transistors (FET's) and stacked RTD's.

Gating of the two-pore cation channel AtTPC1 in the plant vacuole is based on a single voltage-sensing domain.

PubMed

Jaślan, D; Mueller, T D; Becker, D; Schultz, J; Cuin, T A; Marten, I; Dreyer, I; Schönknecht, G; Hedrich, R

2016-09-01

The two-pore cation channel TPC1 operates as a dimeric channel in animal and plant endomembranes. Each subunit consists of two homologous Shaker-like halves, with 12 transmembrane domains in total (S1-S6, S7-S12). In plants, TPC1 channels reside in the vacuolar membrane, and upon voltage stimulation, give rise to the well-known slow-activating SV currents. Here, we combined bioinformatics, structure modelling, site-directed mutagenesis, and in planta patch clamp studies to elucidate the molecular mechanisms of voltage-dependent channel gating in TPC1 in its native plant background. Structure-function analysis of the Arabidopsis TPC1 channel in planta confirmed that helix S10 operates as the major voltage-sensing site, with Glu450 and Glu478 identified as possible ion-pair partners for voltage-sensing Arg537. The contribution of helix S4 to voltage sensing was found to be negligible. Several conserved negative residues on the luminal site contribute to calcium binding, stabilizing the closed channel. During evolution of plant TPC1s from two separate Shaker-like domains, the voltage-sensing function in the N-terminal Shaker-unit (S1-S4) vanished. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

14 CFR 29.1351 - General.

Code of Federal Regulations, 2011 CFR

2011-01-01

...— (1) Be determined by an electrical load analysis; and (2) Meet the requirements of § 29.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of essential load...

14 CFR 29.1351 - General.

Code of Federal Regulations, 2014 CFR

2014-01-01

...— (1) Be determined by an electrical load analysis; and (2) Meet the requirements of § 29.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of essential load...

14 CFR 25.1351 - General.

Code of Federal Regulations, 2014 CFR

2014-01-01

...) Be determined by an electrical load analysis; and (2) Meet the requirements of § 25.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of all essential load...

14 CFR 29.1351 - General.

Code of Federal Regulations, 2013 CFR

2013-01-01

...— (1) Be determined by an electrical load analysis; and (2) Meet the requirements of § 29.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of essential load...

14 CFR 29.1351 - General.

Code of Federal Regulations, 2012 CFR

2012-01-01

...— (1) Be determined by an electrical load analysis; and (2) Meet the requirements of § 29.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of essential load...

14 CFR 29.1351 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

...— (1) Be determined by an electrical load analysis; and (2) Meet the requirements of § 29.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of essential load...

14 CFR 25.1351 - General.

Code of Federal Regulations, 2013 CFR

2013-01-01

...) Be determined by an electrical load analysis; and (2) Meet the requirements of § 25.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of all essential load...

14 CFR 25.1351 - General.

Code of Federal Regulations, 2010 CFR

2010-01-01

...) Be determined by an electrical load analysis; and (2) Meet the requirements of § 25.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of all essential load...

14 CFR 25.1351 - General.

Code of Federal Regulations, 2011 CFR

2011-01-01

...) Be determined by an electrical load analysis; and (2) Meet the requirements of § 25.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of all essential load...

14 CFR 25.1351 - General.

Code of Federal Regulations, 2012 CFR

2012-01-01

...) Be determined by an electrical load analysis; and (2) Meet the requirements of § 25.1309. (b...) Power sources function properly when independent and when connected in combination; (2) No failure or... essential loads; (3) The system voltage and frequency (as applicable) at the terminals of all essential load...

Computerized Investigations of Battery Characteristics.

ERIC Educational Resources Information Center

Hinrichsen, P. F.

2001-01-01

Uses a computer interface to measure terminal voltage versus current characteristic of a variety of batteries, their series and parallel combinations, and the variation with discharge. The concept of an internal resistance demonstrates that current flows through the battery determine the efficiency and serve to introduce Thevenin's theorem.…

A new fast-cycling system for AMS at ANU

NASA Astrophysics Data System (ADS)

De Cesare, M.; Fifield, L. K.; Weisser, D. C.; Tsifakis, D.; Cooper, A.; Lobanov, N. R.; Tunningley, T. B.; Tims, S. G.; Wallner, A.

2015-10-01

In order to perform higher precision measurements, an upgrade of the ANU accelerator is underway. Fast switching times on the low-energy side, with maximum settling times of 30 ms, are achieved by holding the injector magnet field constant while changing the energy of the different isotopes by changing the pre-acceleration voltage after the ion source. Because ions of the different isotopes then have different energies before injection, it is necessary to adjust the strength and steering of the electrostatic quadrupole lens that focusses the beam before entry into the accelerator. First tests of the low-energy system will be reported. At the high energy end, a larger vacuum box in the analyzing magnet has been designed, manufactured and installed to allow the transport of differences in mass as large as 10% at constant terminal voltage. For the cases where more than one isotope must be transported to the detector an additional refinement is necessary. If the accelerator voltage is to be kept constant, then the trajectories of the different isotopes around both the analyzing and switching magnets must be modified. This will be achieved using bounced electrostatic steerers before and after the magnets. Simulations have been performed with the ion optic code COSY Infinity to determine the optimal positions and sizes of these steerers.

Gating of the designed trimeric/tetrameric voltage-gated H+ channel

PubMed Central

Fujiwara, Yuichiro; Kurokawa, Tatsuki; Takeshita, Kohei; Nakagawa, Atsushi; Larsson, H Peter; Okamura, Yasushi

2013-01-01

The voltage-gated H+ channel functions as a dimer, a configuration that is different from standard tetrameric voltage-gated channels. Each channel protomer has its own permeation pathway. The C-terminal coiled-coil domain has been shown to be necessary for both dimerization and cooperative gating in the two channel protomers. Here we report the gating cooperativity in trimeric and tetrameric Hv channels engineered by altering the hydrophobic core sequence of the coiled-coil assembly domain. Trimeric and tetrameric channels exhibited more rapid and less sigmoidal kinetics of activation of H+ permeation than dimeric channels, suggesting that some channel protomers in trimers and tetramers failed to produce gating cooperativity observed in wild-type dimers. Multimerization of trimer and tetramer channels were confirmed by the biochemical analysis of proteins, including crystallography. These findings indicate that the voltage-gated H+ channel is optimally designed as a dimeric channel on a solid foundation of the sequence pattern of the coiled-coil core, with efficient cooperative gating that ensures sustained and steep voltage-dependent H+ conductance in blood cells. PMID:23165764

Response of geostationary communications satellite solid-state power amplifiers to high-energy electron fluence

NASA Astrophysics Data System (ADS)

Lohmeyer, Whitney; Carlton, Ashley; Wong, Frankie; Bodeau, Michael; Kennedy, Andrew; Cahoy, Kerri

2015-05-01

The key components in communications satellite payloads are the high-power amplifiers that amplify the received signal so that it can be accurately transmitted to the intended end user. In this study, we examine 26 amplifier anomalies and quantify the high-energy electron environment for periods of time prior to the anomalies. Building on the work of Lohmeyer and Cahoy (2013), we find that anomalies occur at a rate higher than just by chance when the >2 MeV electron fluence accumulated over 14 and 21 days is elevated. To try to understand "why," we model the amplifier subsystem to assess whether the dielectric material in the radio frequency (RF) coaxial cables, which are the most exposed part of the system, is liable to experience electrical breakdown due to internal charging. We find that the accumulated electric field over the 14 and 21 days leading up to the anomalies is high enough to cause the dielectric material in the coax to breakdown. We also find that the accumulated voltages reached are high enough to compromise components in the amplifier system, for example, the direct current (DC) blocking capacitor. An electron beam test using a representative coaxial cable terminated in a blocking capacitor showed that discharges could occur with peak voltages and energies sufficient to damage active RF semiconductor devices.

Atomically engineered epitaxial anatase TiO 2 metal-semiconductor field-effect transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Brian S. Y.; Minohara, Makoto; Hikita, Yasuyuki

Here, anatase TiO 2 is a promising material for a vast array of electronic, energy, and environmental applications, including photocatalysis, photovoltaics, and sensors. A key requirement for these applications is the ability to modulate its electrical properties without dominant dopant scattering and while maintaining high carrier mobility. Here, we demonstrate the room temperature field-effect modulation of the conducting epitaxial interface between anatase TiO 2 and LaAlO 3 (001), which arises for LaO-terminated LaAlO 3, while the AlO 2-terminated interface is insulating. This approach, together with the metal-semiconductor field-effect transistor geometry, naturally bypasses the gate/channel interface traps, resulting in a highmore » field-effect mobility μ FE of 3.14 cm 2 (V s) –1 approaching 98% of the corresponding Hall mobility μ Hall. Accordingly, the channel conductivity is modulated over 6 orders of magnitude over a gate voltage range of ~4 V.« less

Separation of heat and charge currents for boosted thermoelectric conversion

NASA Astrophysics Data System (ADS)

Mazza, Francesco; Valentini, Stefano; Bosisio, Riccardo; Benenti, Giuliano; Giovannetti, Vittorio; Fazio, Rosario; Taddei, Fabio

2015-06-01

In a multiterminal device the (electronic) heat and charge currents can follow different paths. In this paper we introduce and analyze a class of multiterminal devices where this property is pushed to its extreme limits, with charge and heat currents flowing in different reservoirs. After introducing the main characteristics of this heat-charge current separation regime, we show how to realize it in a multiterminal device with normal and superconducting leads. We demonstrate that this regime allows us to control independently heat and charge flows and to greatly enhance thermoelectric performances at low temperatures. We analyze in detail a three-terminal setup involving a superconducting lead, a normal lead, and a voltage probe. For a generic scattering region we show that in the regime of heat-charge current separation both the power factor and the figure of merit Z T are highly increased with respect to a standard two-terminal system. These results are confirmed for the specific case of a system consisting of three coupled quantum dots.

Development, Demonstration, and Control of a Testbed for Multiterminal HVDC System

DOE PAGES

Li, Yalong; Shi, Xiaojie M.; Liu, Bo; ...

2016-10-21

This paper presents the development of a scaled four-terminal high-voltage direct current (HVDC) testbed, including hardware structure, communication architecture, and different control schemes. The developed testbed is capable of emulating typical operation scenarios including system start-up, power variation, line contingency, and converter station failure. Some unique scenarios are also developed and demonstrated, such as online control mode transition and station re-commission. In particular, a dc line current control is proposed, through the regulation of a converter station at one terminal. By controlling a dc line current to zero, the transmission line can be opened by using relatively low-cost HVDC disconnectsmore » with low current interrupting capability, instead of the more expensive dc circuit breaker. Utilizing the dc line current control, an automatic line current limiting scheme is developed. As a result, when a dc line is overloaded, the line current control will be automatically activated to regulate current within the allowable maximum value.« less

Atomically engineered epitaxial anatase TiO 2 metal-semiconductor field-effect transistors

DOE PAGES

Kim, Brian S. Y.; Minohara, Makoto; Hikita, Yasuyuki; ...

2018-03-26

Here, anatase TiO 2 is a promising material for a vast array of electronic, energy, and environmental applications, including photocatalysis, photovoltaics, and sensors. A key requirement for these applications is the ability to modulate its electrical properties without dominant dopant scattering and while maintaining high carrier mobility. Here, we demonstrate the room temperature field-effect modulation of the conducting epitaxial interface between anatase TiO 2 and LaAlO 3 (001), which arises for LaO-terminated LaAlO 3, while the AlO 2-terminated interface is insulating. This approach, together with the metal-semiconductor field-effect transistor geometry, naturally bypasses the gate/channel interface traps, resulting in a highmore » field-effect mobility μ FE of 3.14 cm 2 (V s) –1 approaching 98% of the corresponding Hall mobility μ Hall. Accordingly, the channel conductivity is modulated over 6 orders of magnitude over a gate voltage range of ~4 V.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reason, J.

Transmission terminations available today are very reliable, but they need to be. In the field, they are continually exposed to pollution and extremes of ambient temperature. In many cases, they are in the rifle sights of vandals. In contrast, cable joints - often cited as the weakest links from an electrical viewpoint - are generally protected from physical damage underground and many of the short cable systems being installed in the US today can be built without joints. All cable systems need terminations - mostly to air-insulated equipment. At 69 through 138 kV, there is intense competition among manufacturers tomore » supply terminations for solid-dielectric cable that are low in cost, reliable, and require a minimum of skill to install. Some utilities are looking also for terminations that fit a range of cable sizes; terminations that do not contain liquid that can leak out; and terminations that are shatter-proof. All of these improvements are available in the US up to 69 kV. For higher voltages, they are on the horizon, if not already in use, overseas. 16 figs.« less

Development of a Tandem-Electrostatic-Quadrupole facility for Accelerator-Based Boron Neutron Capture Therapy.

PubMed

Kreiner, A J; Castell, W; Di Paolo, H; Baldo, M; Bergueiro, J; Burlon, A A; Cartelli, D; Vento, V Thatar; Kesque, J M; Erhardt, J; Ilardo, J C; Valda, A A; Debray, M E; Somacal, H R; Sandin, J C Suarez; Igarzabal, M; Huck, H; Estrada, L; Repetto, M; Obligado, M; Padulo, J; Minsky, D M; Herrera, M; Gonzalez, S J; Capoulat, M E

2011-12-01

We describe the present status of an ongoing project to develop a Tandem-ElectroStatic-Quadrupole (TESQ) accelerator facility for Accelerator-Based (AB)-BNCT. The project final goal is a machine capable of delivering 30 mA of 2.4 MeV protons to be used in conjunction with a neutron production target based on the (7)Li(p,n)(7)Be reaction. The machine currently being constructed is a folded TESQ with a high-voltage terminal at 0.6 MV. We report here on the progress achieved in a number of different areas. Copyright © 2011 Elsevier Ltd. All rights reserved.

A power-efficient switchable CML driver at 10 Gbps

NASA Astrophysics Data System (ADS)

Peipei, Chen; Lei, Li; Huihua, Liu

2016-02-01

High static power limits the application of conventional current-mode logic(CML). This paper presents a power-efficient switchable CML driver, which achieves a significant current saving by 75% compared with conventional ones. Implemented in the 130 nm CMOS technology process, the proposed CML driver just occupies an area about 0.003 mm2 and provides a robust differential signal of 1600 mV for 10 Gbps optical line terminal (OLT) with a total current of 10 mA. The peak-to-peak jitter is about 4 ps (0.04TUI) and the offset voltage is 347.2 mV @ 1600 mVPP.

Oligonucleotide probes functionalization of nanogap electrodes.

PubMed

Zaffino, Rosa Letizia; Mir, Mònica; Samitier, Josep

2017-11-01

Nanogap electrodes have attracted a lot of consideration as promising platform for molecular electronic and biomolecules detection. This is mainly for their higher aspect ratio, and because their electrical properties are easily accessed by current-voltage measurements. Nevertheless, application of standard current-voltages measurements used to characterize nanogap response, and/or to modify specific nanogap electrodes properties, represents an issue. Since the strength of electrical fields in nanoscaled devices can reach high values, even at low voltages. Here, we analyzed the effects induced by different methods of surface modification of nanogap electrodes, in test-voltage application, employed for the electrical detection of a desoxyribonucleic acid (DNA) target. Nanogap electrodes were functionalized with two antisymmetric oligo-probes designed to have 20 terminal bases complementary to the edges of the target, which after hybridization bridges the nanogap, closing the electrical circuit. Two methods of functionalization were studied for this purpose; a random self-assembling of a mixture of the two oligo-probes (OPs) used in the platform, and a selective method that controls the position of each OP at selected side of nanogap electrodes. We used for this aim, the electrophoretic effect induced on negatively charged probes by the application of an external direct current voltage. The results obtained with both functionalization methods where characterized and compared in terms of electrode surface covering, calculated by using voltammetry analysis. Moreover, we contrasted the electrical detection of a DNA target in the nanogap platform either in site-selective and in randomly assembled nanogap. According to our results, a denser, although not selective surface functionalization, is advantageous for such kind of applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface and Interface Chemistry for Gate Stacks on Silicon

NASA Astrophysics Data System (ADS)

Frank, M. M.; Chabal, Y. J.

This chapter addresses the fundamental silicon surface science associated with the continued progress of nanoelectronics along the path prescribed by Moore's law. Focus is on hydrogen passivation layers and on ultrathin oxide films encountered during silicon cleaning and gate stack formation in the fabrication of metal-oxide-semiconductor field-effect transistors (MOSFETs). Three main topics are addressed. (i) First, the current practices and understanding of silicon cleaning in aqueous solutions are reviewed, including oxidizing chemistries and cleans leading to a hydrogen passivation layer. The dependence of the final surface termination and morphology/roughness on reactant choice and pH and the influence of impurities such as dissolved oxygen or metal ions are discussed. (ii) Next, the stability of hydrogen-terminated silicon in oxidizing liquid and gas phase environments is considered. In particular, the remarkable stability of hydrogen-terminated silicon surface in pure water vapor is discussed in the context of atomic layer deposition (ALD) of high-permittivity (high-k) gate dielectrics where water is often used as an oxygen precursor. Evidence is also provided for co-operative action between oxygen and water vapor that accelerates surface oxidation in humid air. (iii) Finally, the fabrication of hafnium-, zirconium- and aluminum-based high-k gate stacks is described, focusing on the continued importance of the silicon/silicon oxide interface. This includes a review of silicon surface preparation by wet or gas phase processing and its impact on high-k nucleation during ALD growth, and the consideration of gate stack capacitance and carrier mobility. In conclusion, two issues are highlighted: the impact of oxygen vacancies on the electrical characteristics of high-k MOS devices, and the way alloyed metal ions (such as Al in Hf-based gate stacks) in contact with the interfacial silicon oxide layer can be used to control flatband and threshold voltages.

Design and analysis of 30 nm T-gate InAlN/GaN HEMT with AlGaN back-barrier for high power microwave applications

NASA Astrophysics Data System (ADS)

Murugapandiyan, P.; Ravimaran, S.; William, J.; Meenakshi Sundaram, K.

2017-11-01

In this article, we present the DC and microwave characteristics of a novel 30 nm T-gate InAlN/AlN/GaN HEMT with AlGaN back-barrier. The device structure is simulated by using Synopsys Sentaurus TCAD Drift-Diffusion transport model at room temperature. The device features are heavily doped (n++ GaN) source/drain regions with Si3N4 passivated device surface for reducing the contact resistances and gate capacitances of the device, which uplift the microwave characteristics of the HEMTs. 30 nm gate length D-mode (E-mode) HEMT exhibited a peak drain current density Idmax of 2.3 (2.42) A/mm, transconductance gm of 1.24(1.65) S/mm, current gain cut-off frequency ft of 262 (246) GHz, power gain cut-off frequency fmax of 246(290) GHz and the three terminal off-state breakdown voltage VBR of 40(38) V. The preeminent microwave characteristics with the higher breakdown voltage of the proposed GaN-based HEMT are the expected to be the most optimistic applicant for future high power millimeter wave applications.

Evaluation and Application of Overvoltage into Communication Equipment Due to Potential Rise at Earthing Terminal of Distribution Line Induced by Lightning Surge

NASA Astrophysics Data System (ADS)

Ito, Katsuji; Hirose, Yasuo

Overvoltage induced by surge currents due to thunderstorm lightnings causes harmful breakdown troubles of CATV communication equipment installed in and with power distribution systems. In this paper, the origin and natures of surge currents, their invading route into the system, and the system components such as earth impedances affecting over voltages are studied. Transient analyses are then performed using an equivalent circuit to evaluate over voltages. Application of the obtained results to the field fault data of communication equipment and possible protection method of them are discussed.

A graphene integrated highly transparent resistive switching memory device

NASA Astrophysics Data System (ADS)

Dugu, Sita; Pavunny, Shojan P.; Limbu, Tej B.; Weiner, Brad R.; Morell, Gerardo; Katiyar, Ram S.

2018-05-01

We demonstrate the hybrid fabrication process of a graphene integrated highly transparent resistive random-access memory (TRRAM) device. The indium tin oxide (ITO)/Al2O3/graphene nonvolatile memory device possesses a high transmittance of >82% in the visible region (370-700 nm) and exhibits stable and non-symmetrical bipolar switching characteristics with considerably low set and reset voltages (<±1 V). The vertical two-terminal device shows an excellent resistive switching behavior with a high on-off ratio of ˜5 × 103. We also fabricated a ITO/Al2O3/Pt device and studied its switching characteristics for comparison and a better understanding of the ITO/Al2O3/graphene device characteristics. The conduction mechanisms in high and low resistance states were analyzed, and the observed polarity dependent resistive switching is explained based on electro-migration of oxygen ions.

CMOS compatible thin-film ALD tungsten nanoelectromechanical devices

NASA Astrophysics Data System (ADS)

Davidson, Bradley Darren

This research focuses on the development of a novel, low-temperature, CMOS compatible, atomic-layer-deposition (ALD) enabled NEMS fabrication process for the development of ALD Tungsten (WALD) NEMS devices. The devices are intended for use in CMOS/NEMS hybrid systems, and NEMS based micro-processors/controllers capable of reliable operation in harsh environments not accessible to standard CMOS technologies. The majority of NEMS switches/devices to date have been based on carbon-nano-tube (CNT) designs. The devices consume little power during actuation, and as expected, have demonstrated actuation voltages much smaller than MEMS switches. Unfortunately, NEMS CNT switches are not typically CMOS integrable due to the high temperatures required for their growth, and their fabrication typically results in extremely low and unpredictable yields. Thin-film NEMS devices offer great advantages over reported CNT devices for several reasons, including: higher fabrication yields, low-temperature (CMOS compatible) deposition techniques like ALD, and increased control over design parameters/device performance metrics, i.e., device geometry. Furthermore, top-down, thin-film, nano-fabrication techniques are better capable of producing complicated device geometries than CNT based processes, enabling the design and development of multi-terminal switches well-suited for low-power hybrid NEMS/CMOS systems as well as electromechanical transistors and logic devices for use in temperature/radiation hard computing architectures. In this work several novel, low-temperature, CMOS compatible fabrication technologies, employing WALD as a structural layer for MEMS or NEMS devices, were developed. The technologies developed are top-down nano-scale fabrication processes based on traditional micro-machining techniques commonly used in the fabrication of MEMS devices. Using these processes a variety of novel WALD NEMS devices have been successfully fabricated and characterized. Using two different WALD fabrication technologies two generations of 2-terminal WALD NEMS switches have been developed. These devices have functional gap heights of 30-50 nm, and actuation voltages typically ranging from 3--5 Volts. Via the extension of a two terminal WALD technology novel 3-terminal WALD NEMS devices were developed. These devices have actuation voltages ranging from 1.5--3 Volts, reliabilities in excess of 2 million cycles, and have been designed to be the fundamental building blocks for WALD NEMS complementary inverters. Through the development of these devices several advancements in the modeling and design of thin-film NEMS devices were achieved. A new model was developed to better characterize pre-actuation currents commonly measured for NEMS switches with nano-scale gate-to-source gap heights. The developed model is an extension of the standard field-emission model and considers the electromechanical response, and electric field effects specific to thin-film NEMS switches. Finally, a multi-physics FEM/FD based model was developed to simulate the dynamic behavior of 2 or 3-terminal electrostatically actuated devices whose electrostatic domains have an aspect ratio on the order of 10-3. The model uses a faux-Lagrangian finite difference method to solve Laplaces equation in a quasi-statatically deforming domain. This model allows for the numerical characterization and design of thin-film NEMS devices not feasible using typical non-specialized BEM/FEM based software. Using this model several novel and feasible designs for fixed-fixed 3-terminal WALD NEMS switches capable for the construction of complementary inverters were discovered.

A Laboratory Exercise with Related Rates.

ERIC Educational Resources Information Center

Sworder, Steven C.

A laboratory experiment, based on a simple electric circuit that can be used to demonstrate the existence of real-world "related rates" problems, is outlined and an equation for voltage across the capacitor terminals during discharge is derived. The necessary materials, setup methods, and experimental problems are described. A student laboratory…

Standard-Cell, Open-Architecture Power Conversion Systems

DTIC Science & Technology

2005-10-01

TLmax Maximum junction temperature 423 OK Table 5. 9. PEBB average model description in VTB. Terminal Type Name - 4 -, A Power DC Bus + B Power AC Pole...5 A. Switching models ........................................................................................ 5 B. Average ...11-6 IV. Average Modeling of PEBB-Based Converters...................................................... 11-10 0 IV. 1.Voltage

Designing, Constructing, and Using an Inexpensive Electronic Buret

ERIC Educational Resources Information Center

Cao, Tingting; Zhang, Qing; Thompson, Jonathan E.

2015-01-01

A syringe-based, electronic fluid dispenser is described. The device mechanically connects a syringe plunger to a linear slide potentiometer. As the syringe plunger moves, the electrical resistance between terminals of the potentiometer varies. Application and subsequent measurement of a DC voltage between the potentiometer pins is used to track…

Effect of Reverse Bias Stress on Leakage Currents and Breakdown Voltages of Solid Tantalum Capacitors

NASA Technical Reports Server (NTRS)

Teverovsky, Alexander A.

2011-01-01

The majority of solid tantalum capacitors are produced by high-temperature sintering of a fine tantalum powder around a tantalum wire followed by electrolytic anodization that forms a thin amorphous Ta2O5 dielectric layer and pyrolysis of manganese nitrite on the oxide to create a conductive manganese dioxide electrode. A contact to tantalum wire is used as anode terminal and to the manganese layer as a cathode terminal of the device. This process results in formation of an asymmetric Ta -- Ta2O5 -- MnO2 capacitor that has different characteristics at forward (positive bias applied to tantalum) and reverse (positive bias applied to manganese cathode) voltages. Reverse bias currents might be several orders of magnitude larger than forward leakage currents so I-V characteristics of tantalum capacitors resemble characteristics of semiconductor rectifiers. Asymmetric I-V characteristics of Ta -- anodic Ta2O5 systems have been observed at different top electrode materials including metals, electrolytes, conductive polymers, and manganese oxide thus indicating that this phenomenon is likely related to the specifics of the Ta -- Ta2O5 interface. There have been multiple attempts to explain rectifying characteristics of capacitors employing anodic tantalum pentoxide dielectrics. A brief review of works related to reverse bias (RB) behavior of tantalum capacitors shows that the mechanism of conduction in Ta -- Ta2O5 systems is still not clear and more testing and analysis is necessary to understand the processes involved. If tantalum capacitors behave just as rectifiers, then the assessment of the safe reverse bias operating conditions would be a relatively simple task. Unfortunately, these parts can degrade with time under reverse bias significantly, and this further complicates analysis of the I-V characteristics and establishing safe operating areas of the parts. On other hand, time dependence of reverse currents might provide additional information for investigation of the processes under reverse bias conditions. In practice, there were instances when, due to unforeseen events, the system operated at conditions when capacitors experience periodically a relatively small reverse bias for some time followed by normal, forward bias conditions. In such a case an assessment should be made on the degree to which these capacitors are degraded by application of low-voltage reverse bias, and whether this degradation can be reversed by normal operating conditions. In this study, reverse currents in different types of tantalum capacitors were monitored at different reverse voltages below 15%VR and temperatures in the range from room to 145 C for up to 150 hours to get better understanding of the degradation process and determine conditions favorable to the unstable mode of operation. The reversibility of RB degradation has been evaluated after operation of the capacitors at forward bias conditions. The effect of reverse bias stress (RBS) on reliability at normal operating conditions was evaluated using highly accelerated life testing at voltages of 1.5VR and 2 VR and by analysis of changes in distributions of breakdown voltages. Possible mechanisms of RB degradation are discussed.

Disruption of the IS6-AID linker affects voltage-gated calcium channel inactivation and facilitation.

PubMed

Findeisen, Felix; Minor, Daniel L

2009-03-01

Two processes dominate voltage-gated calcium channel (Ca(V)) inactivation: voltage-dependent inactivation (VDI) and calcium-dependent inactivation (CDI). The Ca(V)beta/Ca(V)alpha(1)-I-II loop and Ca(2+)/calmodulin (CaM)/Ca(V)alpha(1)-C-terminal tail complexes have been shown to modulate each, respectively. Nevertheless, how each complex couples to the pore and whether each affects inactivation independently have remained unresolved. Here, we demonstrate that the IS6-alpha-interaction domain (AID) linker provides a rigid connection between the pore and Ca(V)beta/I-II loop complex by showing that IS6-AID linker polyglycine mutations accelerate Ca(V)1.2 (L-type) and Ca(V)2.1 (P/Q-type) VDI. Remarkably, mutations that either break the rigid IS6-AID linker connection or disrupt Ca(V)beta/I-II association sharply decelerate CDI and reduce a second Ca(2+)/CaM/Ca(V)alpha(1)-C-terminal-mediated process known as calcium-dependent facilitation. Collectively, the data strongly suggest that components traditionally associated solely with VDI, Ca(V)beta and the IS6-AID linker, are essential for calcium-dependent modulation, and that both Ca(V)beta-dependent and CaM-dependent components couple to the pore by a common mechanism requiring Ca(V)beta and an intact IS6-AID linker.

Unfolding of a Temperature-Sensitive Domain Controls Voltage-Gated Channel Activation.

PubMed

Arrigoni, Cristina; Rohaim, Ahmed; Shaya, David; Findeisen, Felix; Stein, Richard A; Nurva, Shailika Reddy; Mishra, Smriti; Mchaourab, Hassane S; Minor, Daniel L

2016-02-25

Voltage-gated ion channels (VGICs) are outfitted with diverse cytoplasmic domains that impact function. To examine how such elements may affect VGIC behavior, we addressed how the bacterial voltage-gated sodium channel (BacNa(V)) C-terminal cytoplasmic domain (CTD) affects function. Our studies show that the BacNa(V) CTD exerts a profound influence on gating through a temperature-dependent unfolding transition in a discrete cytoplasmic domain, the neck domain, proximal to the pore. Structural and functional studies establish that the BacNa(V) CTD comprises a bi-partite four-helix bundle that bears an unusual hydrophilic core whose integrity is central to the unfolding mechanism and that couples directly to the channel activation gate. Together, our findings define a general principle for how the widespread four-helix bundle cytoplasmic domain architecture can control VGIC responses, uncover a mechanism underlying the diverse BacNa(V) voltage dependencies, and demonstrate that a discrete domain can encode the temperature-dependent response of a channel. Copyright © 2016 Elsevier Inc. All rights reserved.

Unfolding of a temperature-sensitive domain controls voltage-gated channel activation

PubMed Central

Arrigoni, Cristina; Rohaim, Ahmed; Shaya, David; Findeisen, Felix; Stein, Richard A.; Nurva, Shailika Reddy; Mishra, Smriti; Mchaourab, Hassane S.; Minor, Daniel L.

2016-01-01

Voltage-gated ion channels (VGICs) are outfitted with diverse cytoplasmic domains that impact function. To examine how such elements may affect VGIC behavior, we addressed how the bacterial voltage-gated sodium channel (BacNaV) C-terminal cytoplasmic domain (CTD) affects function. Our studies show that the BacNaV CTD exerts a profound influence on gating through a temperature-dependent unfolding transition in a discrete cytoplasmic domain, the neck domain, proximal to the pore. Structural and functional studies establish that the BacNaV CTD comprises a bi-partite four-helix bundle that bears an unusual hydrophilic core whose integrity is central to the unfolding mechanism and that couples directly to the channel activation gate. Together, our findings define a general principle for how the widespread four-helix bundle cytoplasmic domain architecture can control VGIC responses, uncover a mechanism underlying the diverse BacNaV voltage dependencies, and demonstrate that a discrete domain can encode the temperature dependent response of a channel. PMID:26919429

Reciprocal voltage sensor-to-pore coupling leads to potassium channel C-type inactivation

PubMed Central

Conti, Luca; Renhorn, Jakob; Gabrielsson, Anders; Turesson, Fredrik; Liin, Sara I; Lindahl, Erik; Elinder, Fredrik

2016-01-01

Voltage-gated potassium channels open at depolarized membrane voltages. A prolonged depolarization causes a rearrangement of the selectivity filter which terminates the conduction of ions – a process called slow or C-type inactivation. How structural rearrangements in the voltage-sensor domain (VSD) cause alteration in the selectivity filter, and vice versa, are not fully understood. We show that pulling the pore domain of the Shaker potassium channel towards the VSD by a Cd2+ bridge accelerates C-type inactivation. Molecular dynamics simulations show that such pulling widens the selectivity filter and disrupts the K+ coordination, a hallmark for C-type inactivation. An engineered Cd2+ bridge within the VSD also affect C-type inactivation. Conversely, a pore domain mutation affects VSD gating-charge movement. Finally, C-type inactivation is caused by the concerted action of distant amino acid residues in the pore domain. All together, these data suggest a reciprocal communication between the pore domain and the VSD in the extracellular portion of the channel. PMID:27278891

Reciprocal voltage sensor-to-pore coupling leads to potassium channel C-type inactivation

NASA Astrophysics Data System (ADS)

Conti, Luca; Renhorn, Jakob; Gabrielsson, Anders; Turesson, Fredrik; Liin, Sara I.; Lindahl, Erik; Elinder, Fredrik

2016-06-01

Voltage-gated potassium channels open at depolarized membrane voltages. A prolonged depolarization causes a rearrangement of the selectivity filter which terminates the conduction of ions - a process called slow or C-type inactivation. How structural rearrangements in the voltage-sensor domain (VSD) cause alteration in the selectivity filter, and vice versa, are not fully understood. We show that pulling the pore domain of the Shaker potassium channel towards the VSD by a Cd2+ bridge accelerates C-type inactivation. Molecular dynamics simulations show that such pulling widens the selectivity filter and disrupts the K+ coordination, a hallmark for C-type inactivation. An engineered Cd2+ bridge within the VSD also affect C-type inactivation. Conversely, a pore domain mutation affects VSD gating-charge movement. Finally, C-type inactivation is caused by the concerted action of distant amino acid residues in the pore domain. All together, these data suggest a reciprocal communication between the pore domain and the VSD in the extracellular portion of the channel.

Abnormal bias dependence of magnetoresistance in CoFeB/MgO/Si spin-injection tunnel contacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, June-Young; Park, Byong-Guk, E-mail: bgpark@kaist.ac.kr; Baek, Seung-heon Chris

We report a strong bias voltage dependence of magnetoresistance (MR) in CoFeB/MgO/Si spin-injection tunnel contacts using the three-terminal Hanle geometry. When a bias voltage is relatively large, the MR is composed of two characteristic signals: a conventional Hanle signal observed at a low magnetic field, which is due to the precession of injected spins, and another signal originating from the rotation of the magnetization at a larger magnetic field. In contrast, for a small bias voltage, additional signals appear at a wide range of magnetic fields, which occasionally overwhelms the conventional Hanle signals. Because the additional signals are pronounced atmore » a low bias and are significantly reduced by annealing at moderate temperatures, they can be attributed to multi-step tunneling via defect states at the interfaces or tunnel barrier. Our results demonstrate that the spin injection signal caused by the defect states can be evaluated by its bias voltage dependence.« less

Structure of a eukaryotic cyclic nucleotide-gated channel

PubMed Central

Li, Minghui; Zhou, Xiaoyuan; Wang, Shu; Michailidis, Ioannis; Gong, Ye; Su, Deyuan; Li, Huan; Li, Xueming; Yang, Jian

2018-01-01

Summary Cyclic nucleotide-gated (CNG) channels are essential for vision and olfaction. They belong to the voltage-gated ion channel superfamily but their activities are controlled by intracellular cyclic nucleotides instead of transmembrane voltage. Here we report a 3.5 Å-resolution single-particle electron cryomicroscopy structure of a CNG channel from C. elegans in the cGMP-bound open state. The channel has an unusual voltage-sensor-like domain (VSLD), accounting for its deficient voltage dependence. A C-terminal linker connecting S6 and the cyclic nucleotide-binding domain interacts directly with both the VSLD and pore domain, forming a gating ring that couples conformational changes triggered by cyclic nucleotide binding to the gate. The selectivity filter is lined by the carboxylate side chains of a functionally important glutamate and three rings of backbone carbonyls. This structure provides a new framework for understanding mechanisms of ion permeation, gating and channelopathy of CNG channels and cyclic nucleotide modulation of related channels. PMID:28099415

Multistage electrotherapy delivered through chronically-implanted leads terminates atrial fibrillation with lower energy than a single biphasic shock.

PubMed

Janardhan, Ajit H; Gutbrod, Sarah R; Li, Wenwen; Lang, Di; Schuessler, Richard B; Efimov, Igor R

The goal of this study was to develop a low-energy, implantable device-based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA-left pulmonary artery and RA-coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein-left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA-left atrium activation until sinus rhythm was restored. Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Multistage Electrotherapy Delivered Through Chronically-Implanted Leads Terminates Atrial Fibrillation With Lower Energy Than a Single Biphasic Shock

PubMed Central

Janardhan, Ajit H.; Gutbrod, Sarah R.; Li, Wenwen; Lang, Di; Schuessler, Richard B.; Efimov, Igor R.

2014-01-01

Objectives The goal of this study was to develop a low-energy, implantable device–based multistage electrotherapy (MSE) to terminate atrial fibrillation (AF). Background Previous attempts to perform cardioversion of AF by using an implantable device were limited by the pain caused by use of a high-energy single biphasic shock (BPS). Methods Transvenous leads were implanted into the right atrium (RA), coronary sinus, and left pulmonary artery of 14 dogs. Self-sustaining AF was induced by 6 ± 2 weeks of high-rate RA pacing. Atrial defibrillation thresholds of standard versus experimental electrotherapies were measured in vivo and studied by using optical imaging in vitro. Results The mean AF cycle length (CL) in vivo was 112 ± 21 ms (534 beats/min). The impedances of the RA–left pulmonary artery and RA–coronary sinus shock vectors were similar (121 ± 11 Ω vs. 126 ± 9 Ω; p = 0.27). BPS required 1.48 ± 0.91 J (165 ± 34 V) to terminate AF. In contrast, MSE terminated AF with significantly less energy (0.16 ± 0.16 J; p < 0.001) and significantly lower peak voltage (31.1 ± 19.3 V; p < 0.001). In vitro optical imaging studies found that AF was maintained by localized foci originating from pulmonary vein–left atrium interfaces. MSE Stage 1 shocks temporarily disrupted localized foci; MSE Stage 2 entrainment shocks continued to silence the localized foci driving AF; and MSE Stage 3 pacing stimuli enabled consistent RA–left atrium activation until sinus rhythm was restored. Conclusions Low-energy MSE significantly reduced the atrial defibrillation thresholds compared with BPS in a canine model of AF. MSE may enable painless, device-based AF therapy. PMID:24076284

Study on deposition of Al2O3 films by plasma-assisted atomic layer with different plasma sources

NASA Astrophysics Data System (ADS)

Haiying, WEI; Hongge, GUO; Lijun, SANG; Xingcun, LI; Qiang, CHEN

2018-04-01

In this paper, Al2O3 thin films are deposited on a hydrogen-terminated Si substrate by using two home-built electron cyclotron resonance (ECR) and magnetic field enhanced radio frequency plasma-assisted atomic layer deposition (PA-ALD) devices with Al(CH3)3 (trimethylaluminum, TMA) and oxygen plasma used as precursor and oxidant, respectively. The thickness, chemical composition, surface morphology and group reactions are characterized by in situ spectroscopic ellipsometer, x-ray photoelectric spectroscopy, atomic force microscopy, scanning electron microscopy, a high-resolution transmission electron microscope and in situ mass spectrometry (MS), respectively. We obtain that both ECR PA-ALD and the magnetic field enhanced PA-ALD can deposit thin films with high density, high purity, and uniformity at a high deposition rate. MS analysis reveals that the Al2O3 deposition reactions are not simple reactions between TMA and oxygen plasma to produce alumina, water and carbon dioxide. In fact, acetylene, carbon monoxide and some other by-products also appear in the exhaustion gas. In addition, the presence of bias voltage has a certain effect on the deposition rate and surface morphology of films, which may be attributed to the presence of bias voltage controlling the plasma energy and density. We conclude that both plasma sources have a different deposition mechanism, which is much more complicated than expected.

Phosphorylation of rat brain purified mitochondrial Voltage-Dependent Anion Channel by c-Jun N-terminal kinase-3 modifies open-channel noise.

PubMed

Gupta, Rajeev

2017-09-02

The drift kinetic energy of ionic flow through single ion channels cause vibrations of the pore walls which are observed as open-state current fluctuations (open-channel noise) during single-channel recordings. Vibration of the pore wall leads to transitions among different conformational sub-states of the channel protein in the open-state. Open-channel noise analysis can provide important information about the different conformational sub-state transitions and how biochemical modifications of ion channels would affect their transport properties. It has been shown that c-Jun N-terminal kinase-3 (JNK3) becomes activated by phosphorylation in various neurodegenerative diseases and phosphorylates outer mitochondrion associated proteins leading to neuronal apoptosis. In our earlier work, JNK3 has been reported to phosphorylate purified rat brain mitochondrial voltage-dependent anion channel (VDAC) in vitro and modify its conductance and opening probability. In this article we have compared the open-state noise profile of the native and the JNK3 phosphorylated VDAC using Power Spectral Density vs frequency plots. Power spectral density analysis of open-state noise indicated power law with average slope value α ≈1 for native VDAC at both positive and negative voltage whereas average α value < 0.5 for JNK3 phosphorylated VDAC at both positive and negative voltage. It is proposed that 1/f 1 power law in native VDAC open-state noise arises due to coupling of ionic transport and conformational sub-states transitions in open-state and this coupling is perturbed as a result of channel phosphorylation. Copyright © 2017 Elsevier Inc. All rights reserved.

Four-terminal electrical testing device. [initiator bridgewire resistance

NASA Technical Reports Server (NTRS)

Robinson, Robert L. (Inventor); Graves, Thomas J. (Inventor); Hoffman, William C., III (Inventor)

1987-01-01

The invention relates to a four-terminal electrical connector device for testing and measuring unknown resistances of initiators used for starting pyrotechnic events aboard the space shuttle. The testing device minimizes contact resistance degradation effects and so improves the reliability of resistance measurements taken with the device. Separate and independent voltage sensing and current supply circuits each include a pair of socket contacts for mating engagement with the pins of the initiator. The unknown resistance that is measured by the device is the resistance of the bridgewire of the initiator which is required to be between 0.95 and 1.15 ohms.

A pH-dependent conformational ensemble mediates proton transport through the influenza A/M2 protein†

PubMed Central

Polishchuk, Alexei L.; Lear, James D.; Ma, Chunlong; Lamb, Robert A.; Pinto, Lawrence H.; DeGrado, William F.

2010-01-01

The influenza A M2 protein exhibits inwardly rectifying, pH-activated proton transport that saturates at low pH. A comparison of high-resolution structures of the transmembrane domain at high and low pH suggests that pH-dependent conformational changes may facilitate proton conduction by alternately changing the accessibility of the N-terminal and C-terminal regions of the channel as a proton transits through the transmembrane domain. Here, we show that M2 functionally reconstituted in liposomes populates at least three different conformational states over a physiologically relevant pH range, with transition midpoints that are consistent with previously reported His37 pKas. We then develop and test two similar, quantitative mechanistic models of proton transport, where protonation shifts the equilibrium between structural states having different proton affinities and solvent accessibilities. The models account well for a collection of experimental data sets over a wide range of pHs and voltages and require only a small number of adjustable parameters to accurately describe the data. While the kinetic models do not require any specific conformation for the protein, they nevertheless are consistent with a large body of structural information based on high-resolution NMR and crystallographic structures, optical spectroscopy, and MD calculations. PMID:20968306

Low-Noise Large-Area Photoreceivers with Low Capacitance Photodiodes

NASA Technical Reports Server (NTRS)

Joshi, Abhay M. (Inventor); Datta, Shubhashish (Inventor)

2013-01-01

A quad photoreceiver includes a low capacitance quad InGaAs p-i-n photodiode structure formed on an InP (100) substrate. The photodiode includes a substrate providing a buffer layer having a metal contact on its bottom portion serving as a common cathode for receiving a bias voltage, and successive layers deposited on its top portion, the first layer being drift layer, the second being an absorption layer, the third being a cap layer divided into four quarter pie shaped sections spaced apart, with metal contacts being deposited on outermost top portions of each section to provide output terminals, the top portions being active regions for detecting light. Four transimpedance amplifiers have input terminals electrically connected to individual output terminals of each p-i-n photodiode.

Border Collision of Three-Phase Voltage-Source Inverter System with Interacting Loads

NASA Astrophysics Data System (ADS)

Li, Zhen; Liu, Bin; Li, Yining; Wong, Siu-Chung; Liu, Xiangdong; Huang, Yuehui

As a commercial interface, three-phase voltage-source inverters (VSI) are commonly equipped for energy conversion to export DC power from most distributed generation (DG) to the AC utility. Not only do voltage-source converters take charge of converting the power to the loads but support the grid voltage at the point of common connection (PCC) as well, which is dependent on the condition of the grid-connected loads. This paper explores the border collision and its interacting mechanism among the VSI, resistive interacting loads and grids, which manifests as the alternating emergence of the inverting and rectifying operations, where the normal operation is terminated and a new one is assumed. Their mutual effect on the power quality under investigation will cause the circuital stability issue and further deteriorate the voltage regulation capability of VSI by dramatically raising the grid voltage harmonics. It is found in a design-oriented view that the border collision operation will be induced within the unsuitable parameter space with respect to transmission lines of AC grid, resistive loads and internal resistance of VSI. The physical phenomenon is also identified by the theoretical analysis. With numerical simulations for various circuit conditions, the corresponding bifurcation boundaries are collected, where the stability of the system is lost via border collision.

Electrogenic glutamate uptake is a major current carrier in the membrane of axolotl retinal glial cells

NASA Astrophysics Data System (ADS)

Brew, Helen; Attwell, David

1987-06-01

Glutamate is taken up avidly by glial cells in the central nervous system1. Glutamate uptake may terminate the transmitter action of glutamate released from neurons1, and keep extracellular glutamate at concentrations below those which are neurotoxic. We report here that glutamate evokes a large inward current in retinal glial cells which have their membrane potential and intracellular ion concentrations controlled by the whole-cell patch-clamp technique2. This current seems to be due to an electrogenic glutamate uptake carrier, which transports at least two sodium ions with every glutamate anion carried into the cell. Glutamate uptake is strongly voltage-dependent, decreasing at depolarized potentials: when fully activated, it contributes almost half of the conductance in the part of the glial cell membrane facing the retinal neurons. The spatial localization, glutamate affinity and magnitude of the uptake are appropriate for terminating the synaptic action of glutamate released from photoreceptors and bipolar cells. These data challenge present explanations of how the b-wave of the electroretinogram is generated, and suggest a mechanism for non-vesicular voltage-dependent release of glutamate from neurons.

Ferulic Acid Suppresses Glutamate Release Through Inhibition of Voltage-Dependent Calcium Entry in Rat Cerebrocortical Nerve Terminals

PubMed Central

Lin, Tzu Yu; Lu, Cheng Wei; Huang, Shu-Kuei

2013-01-01

Abstract This study investigated the effects and possible mechanism of ferulic acid, a naturally occurring phenolic compound, on endogenous glutamate release in the nerve terminals of the cerebral cortex in rats. Results show that ferulic acid inhibited the release of glutamate evoked by the K+ channel blocker 4-aminopyridine (4-AP). The effect of ferulic acid on the evoked glutamate release was prevented by chelating the extracellular Ca2+ ions, but was insensitive to the glutamate transporter inhibitor DL-threo-beta-benzyl-oxyaspartate. Ferulic acid suppressed the depolarization-induced increase in a cytosolic-free Ca2+ concentration, but did not alter 4-AP–mediated depolarization. Furthermore, the effect of ferulic acid on evoked glutamate release was abolished by blocking the Cav2.2 (N-type) and Cav2.1 (P/Q-type) channels, but not by blocking ryanodine receptors or mitochondrial Na+/Ca2+ exchange. These results show that ferulic acid inhibits glutamate release from cortical synaptosomes in rats through the suppression of presynaptic voltage-dependent Ca2+ entry. PMID:23342970

Nonlinear system analysis in bipolar integrated circuits

NASA Astrophysics Data System (ADS)

Fang, T. F.; Whalen, J. J.

1980-01-01

Since analog bipolar integrated circuits (IC's) have become important components in modern communication systems, the study of the Radio Frequency Interference (RFI) effects in bipolar IC amplifiers is an important subject for electromagnetic compatibility (EMC) engineering. The investigation has focused on using the nonlinear circuit analysis program (NCAP) to predict RF demodulation effects in broadband bipolar IC amplifiers. The audio frequency (AF) voltage at the IC amplifier output terminal caused by an amplitude modulated (AM) RF signal at the IC amplifier input terminal was calculated and compared to measured values. Two broadband IC amplifiers were investigated: (1) a cascode circuit using a CA3026 dual differential pair; (2) a unity gain voltage follower circuit using a micro A741 operational amplifier (op amp). Before using NCAP for RFI analysis, the model parameters for each bipolar junction transistor (BJT) in the integrated circuit were determined. Probe measurement techniques, manufacturer's data, and other researcher's data were used to obtain the required NCAP BJT model parameter values. An important contribution included in this effort is a complete set of NCAP BJT model parameters for most of the transistor types used in linear IC's.

Evaluation program for secondary spacecraft cells: Initial evaluation tests of General Electric Company 40.0 ampere hour nickel cadmium spacecraft cells for the tracking data relay satellite system

NASA Technical Reports Server (NTRS)

Hall, S. W.

1980-01-01

Average end of charge voltages and pressures, and capacity output in ampere hours are presented. Test limits specify those values at which a cell is to be terminated from charge or discharge. Requirements are based on past cell performance data. The requirement does not constitute a limit for discontinuance from testing. The nickel cadmium batteries were screened for internal shorts, low capacity, electrolyte leakage, or inability of any cell to recover its open circuit voltage above 1.150 volts during the internal short test.

Chemical sensors are hybrid-input memristors

NASA Astrophysics Data System (ADS)

Sysoev, V. I.; Arkhipov, V. E.; Okotrub, A. V.; Pershin, Y. V.

2018-04-01

Memristors are two-terminal electronic devices whose resistance depends on the history of input signal (voltage or current). Here we demonstrate that the chemical gas sensors can be considered as memristors with a generalized (hybrid) input, namely, with the input consisting of the voltage, analyte concentrations and applied temperature. The concept of hybrid-input memristors is demonstrated experimentally using a single-walled carbon nanotubes chemical sensor. It is shown that with respect to the hybrid input, the sensor exhibits some features common with memristors such as the hysteretic input-output characteristics. This different perspective on chemical gas sensors may open new possibilities for smart sensor applications.

Design and development of a new-type terminal for smart electricity use in the energy USB system

NASA Astrophysics Data System (ADS)

Wang, Mian; Cheng, Lefeng; Liu, Bin; Jiang, Haorong; Tan, Zhukui; Yu, Tao

2017-11-01

With the in-depth development of energy Internet, the requirements for smart electricity use (SEU) in a comprehensive energy system is higher. Aiming at the current smart electricity controllers that can only realize the monitoring of voltage, current, power and electricity consumption, while neglecting the impact of environmental quality on electricity use behaviours, this paper designs and develops a new type of terminal for SEU in the energy universal service bus system (USB), based on the techniques of digital signal processing, wireless communication and intelligent sensing. A detailed modular hardware design is given for the terminal, as well as the software design, apart from the basic functions, the terminal can complete harmonic analysis, wireless communication, on-off controlling, data display, etc. in addition, take the user perception into account through collecting the ambient temperature and humidity, as well as detecting indoor environment comfort, so that promoting home electricity use optimization. The terminal developed can play an important role in the energy USB system under the background of energy Internet, and the paper ends by giving the testing results which verify the effectiveness, intelligence and practicability of the terminal.

Implementation method of multi-terminal DC control system

NASA Astrophysics Data System (ADS)

Yi, Liu; Hao-Ran, Huang; Jun-Wen, Zhou; Hong-Guang, Guo; Yu-Yong, Zhou

2018-04-01

Currently the multi-terminal DC system (MTDC) has more stations. Each station needs operators to monitor and control the device. It needs much more operation and maintenance, low efficiency and small reliability; for the most important reason, multi-terminal DC system has complex control mode. If one of the stations has some problem, the control of the whole system should have problems. According to research of the characteristics of multi-terminal DC (VSC-MTDC) systems, this paper presents a strong implementation of the multi-terminal DC Supervisory Control and Data Acquisition (SCADA) system. This system is intelligent, can be networking, integration and intelligent. A master control system is added in each station to communication with the other stations to send current and DC voltage value to pole control system for each station. Based on the practical application and information feedback in the China South Power Grid research center VSC-MTDC project, this system is higher efficiency and save the cost on the maintenance of convertor station to improve the intelligent level and comprehensive effect. And because of the master control system, a multi-terminal system hierarchy coordination control strategy is formed, this make the control and protection system more efficiency and reliability.

Charge control microcomputer device for vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morishita, M.; Kouge, S.

1986-10-14

This patent describes a charge control microcomputer device for a vehicle, comprising: speed changing means for transmitting the output torque of an engine. The speed changing means includes a slip clutch means having an output with a variable slippage amount with respect to its input and controlled in accordance with an operating instruction. The speed changing means further includes a speed change gear for changing the rotational speed input thereto at an output thereto, the speed change gear receiving the output of the slip clutch means; a charging generator driven by the output of the speed change gear; a batterymore » charged by an output voltage of the charging generator; a voltage regulator for controlling the output voltage of the charging generator to a predetermined value; an engine controlling microcomputer for receiving data from the engine, to control the engine, the engine data comprising at least an engine speed signal; a charge control microcomputer for processing engine data from the engine controlling microcomputer and charge system data including terminal voltage data from the battery and generated voltage data from the changing generator; and a display unit for displaying detection data, including fault detection data, form the charge control microcomputer.« less

Low-bandgap mixed tin–lead iodide perovskite absorbers with long carrier lifetimes for all-perovskite tandem solar cells

DOE PAGES

Zhao, Dewei; Yu, Yue; Wang, Changlei; ...

2017-03-01

Tandem solar cells using only metal-halide perovskite sub-cells are an attractive choice for next-generation solar cells. However, the progress in developing efficient all-perovskite tandem solar cells has been hindered by the lack of high-performance low-bandgap perovskite solar cells. Here in this paper, we report efficient mixed tin-lead iodide low-bandgap (~1.25 eV) perovskite solar cells with open-circuit voltages up to 0.85 V and over 70% external quantum efficiencies in the infrared wavelength range of 700-900 nm, delivering a short-circuit current density of over 29 mA cm -2 and demonstrating suitability for bottom-cell applications in all-perovskite tandem solar cells. Our low-bandgap perovskitemore » solar cells achieve a maximum power conversion efficiency of 17.6% and a certified efficiency of 17.01% with a negligible current-voltage hysteresis. Finally, when mechanically stacked with a ~1.58 eV bandgap perovskite top cell, our best all-perovskite 4-terminal tandem solar cell shows a steady-state efficiency of 21.0%.« less

Low-bandgap mixed tin–lead iodide perovskite absorbers with long carrier lifetimes for all-perovskite tandem solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Dewei; Yu, Yue; Wang, Changlei

Tandem solar cells using only metal-halide perovskite sub-cells are an attractive choice for next-generation solar cells. However, the progress in developing efficient all-perovskite tandem solar cells has been hindered by the lack of high-performance low-bandgap perovskite solar cells. Here in this paper, we report efficient mixed tin-lead iodide low-bandgap (~1.25 eV) perovskite solar cells with open-circuit voltages up to 0.85 V and over 70% external quantum efficiencies in the infrared wavelength range of 700-900 nm, delivering a short-circuit current density of over 29 mA cm -2 and demonstrating suitability for bottom-cell applications in all-perovskite tandem solar cells. Our low-bandgap perovskitemore » solar cells achieve a maximum power conversion efficiency of 17.6% and a certified efficiency of 17.01% with a negligible current-voltage hysteresis. Finally, when mechanically stacked with a ~1.58 eV bandgap perovskite top cell, our best all-perovskite 4-terminal tandem solar cell shows a steady-state efficiency of 21.0%.« less

Factors that Influence RF Breakdown in Antenna Systems

NASA Astrophysics Data System (ADS)

Caughman, J. B. O.; Baity, F. W.; Rasmussen, D. A.; Aghazarian, M.; Castano Giraldo, C. H.; Ruzic, David

2007-11-01

One of the main power-limiting factors in antenna systems is the maximum voltage that the antenna or vacuum transmission line can sustain before breaking down. The factors that influence RF breakdown are being studied in a resonant 1/4-wavelength section of vacuum transmission line terminated with an open circuit electrode structure. Breakdown can be initiated via electron emission by high electric fields and by plasma formation in the structure, depending on the gas pressure. Recent experiments have shown that a 1 kG magnetic field can influence plasma formation at pressures as low as 8x10-5 Torr at moderate voltage levels (<5 kV). Ultraviolet light, with energies near the work function of the electrode material, can induce a multipactor discharge and limit power transmission. Details of these experimental results, including the effect of electrode materials (Ni and Cu), will be presented. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Dept. of Energy under contract DE-AC05-00OR22725. Work supported by USDOE with grant DE-FG02-04ER54765

If it’s pinched it’s a memristor

NASA Astrophysics Data System (ADS)

Chua, Leon

2014-10-01

This paper presents an in-depth review of the memristor from a rigorous circuit-theoretic perspective, independent of the material the device is made of. From an experimental perspective, a memristor is best defined as any two-terminal device that exhibits a pinched hysteresis loop in the voltage-current plane when driven by any periodic voltage or current signal that elicits a periodic response of the same frequency. This definition greatly broadens the scope of memristive devices to encompass even non-semiconductor devices, both organic and inorganic, from many unrelated disciplines, including biology, botany, brain science, etc. For pedagogical reasons, the broad terrain of memristors is partitioned into three classes of increasing generality, dubbed Ideal Memristors, Generic Memristors, and Extended Memristors. Each class is distinguished from the others via unique fingerprints and signatures. This paper clarifies many confusing issues, such as non-volatility, dc V-I curves, high-frequency v-i curves, local activity, as well as nonlinear dynamical and bifurcation phenomena that are the hallmarks of memristive devices. Above all, this paper addresses several fundamental issues and questions that many memristor researchers do not comprehend but are afraid to ask.

30 CFR 75.826 - High-voltage trailing cables.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage trailing cables. 75.826 Section 75...-Voltage Longwalls § 75.826 High-voltage trailing cables. High-voltage trailing cables must: (a) Meet existing trailing cable requirements and the approval requirements of the high-voltage continuous mining...

Design of power cable grounding wire anti-theft monitoring system

NASA Astrophysics Data System (ADS)

An, Xisheng; Lu, Peng; Wei, Niansheng; Hong, Gang

2018-01-01

In order to prevent the serious consequences of the power grid failure caused by the power cable grounding wire theft, this paper presents a GPRS based power cable grounding wire anti-theft monitoring device system, which includes a camera module, a sensor module, a micro processing system module, and a data monitoring center module, a mobile terminal module. Our design utilize two kinds of methods for detecting and reporting comprehensive image, it can effectively solve the problem of power and cable grounding wire box theft problem, timely follow-up grounded cable theft events, prevent the occurrence of electric field of high voltage transmission line fault, improve the reliability of the safe operation of power grid.

Impact of interfacial resistance switching on thermoelectric effect of Nb-doped SrTiO3 single crystalline

NASA Astrophysics Data System (ADS)

Zhang, Peijian; Meng, Yang; Liu, Ziyu; Li, Dong; Su, Tao; Meng, Qingyu; Mao, Qi; Pan, Xinyu; Chen, Dongmin; Zhao, Hongwu

2012-03-01

The thermoelectric properties of the bistable resistance states in Nb doped SrTiO3 single crystal have been investigated. The Seebeck coefficients for both low and high resistance states change linearly with temperature. The three-terminals contrast measurement demonstrates that a large fraction of the voltage drop is applied at the tiny volume near the bottom interface between the electrode and the oxide bulk. Therefore, the metallic oxide bulk plays a dominant role in the temperature dependence of Seebeck coefficients. The thermoelectric properties of new resistance switching (RS) devices with minimized non-RS volume could be exploited for the RS mechanism and novel applications.

Rocket Propulsion 21 Steering Committee Meeting (RP21) NASA In-Space Propulsion Update

NASA Technical Reports Server (NTRS)

Klem, Mark

2015-01-01

In-house Support of NEXT-C Contract Status Thruster NEXT Long Duration Test post-test destructive evaluation in progress Findings will be used to verify service life models identify potential design improvements Cathode heater fabrication initiated for cyclic life testing Thruster operating algorithm definition verification initiated to provide operating procedures for mission users High voltage propellant isolator life test voluntarily terminated after successfully operating 51,200 h Power processor unit (PPU) Replaced all problematic stacked multilayer ceramic dual inline pin capacitors within PPU Test bed Rebuilt installed discharge power supply primary power board Completed full functional performance characterization Final test report in progress Transferred PPU Testbed to contractor to support prototype design effort.

Sodium Channel β2 Subunits Prevent Action Potential Propagation Failures at Axonal Branch Points.

PubMed

Cho, In Ha; Panzera, Lauren C; Chin, Morven; Hoppa, Michael B

2017-09-27

Neurotransmitter release depends on voltage-gated Na + channels (Na v s) to propagate an action potential (AP) successfully from the axon hillock to a synaptic terminal. Unmyelinated sections of axon are very diverse structures encompassing branch points and numerous presynaptic terminals with undefined molecular partners of Na + channels. Using optical recordings of Ca 2+ and membrane voltage, we demonstrate here that Na + channel β2 subunits (Na v β2s) are required to prevent AP propagation failures across the axonal arborization of cultured rat hippocampal neurons (mixed male and female). When Na v β2 expression was reduced, we identified two specific phenotypes: (1) membrane excitability and AP-evoked Ca 2+ entry were impaired at synapses and (2) AP propagation was severely compromised with >40% of axonal branches no longer responding to AP-stimulation. We went on to show that a great deal of electrical signaling heterogeneity exists in AP waveforms across the axonal arborization independent of axon morphology. Therefore, Na v β2 is a critical regulator of axonal excitability and synaptic function in unmyelinated axons. SIGNIFICANCE STATEMENT Voltage-gated Ca 2+ channels are fulcrums of neurotransmission that convert electrical inputs into chemical outputs in the form of vesicle fusion at synaptic terminals. However, the role of the electrical signal, the presynaptic action potential (AP), in modulating synaptic transmission is less clear. What is the fidelity of a propagating AP waveform in the axon and what molecules shape it throughout the axonal arborization? Our work identifies several new features of AP propagation in unmyelinated axons: (1) branches of a single axonal arborization have variable AP waveforms independent of morphology, (2) Na + channel β2 subunits modulate AP-evoked Ca 2+ -influx, and (3) β2 subunits maintain successful AP propagation across the axonal arbor. These findings are relevant to understanding the flow of excitation in the brain. Copyright © 2017 the authors 0270-6474/17/379519-15$15.00/0.

Low voltage to high voltage level shifter and related methods

NASA Technical Reports Server (NTRS)

Mentze, Erik J. (Inventor); Buck, Kevin M. (Inventor); Hess, Herbert L. (Inventor); Cox, David F. (Inventor)

2006-01-01

A shifter circuit comprises a high and low voltage buffer stages and an output buffer stage. The high voltage buffer stage comprises multiple transistors arranged in a transistor stack having a plurality of intermediate nodes connecting individual transistors along the stack. The transistor stack is connected between a voltage level being shifted to and an input voltage. An inverter of this stage comprises multiple inputs and an output. Inverter inputs are connected to a respective intermediate node of the transistor stack. The low voltage buffer stage has an input connected to the input voltage and an output, and is operably connected to the high voltage buffer stage. The low voltage buffer stage is connected between a voltage level being shifted away from and a lower voltage. The output buffer stage is driven by the outputs of the high voltage buffer stage inverter and the low voltage buffer stage.

Mechanistic insights on spider neurotoxins.

PubMed

Luch, Andreas

2010-01-01

In physiology research, animal neurotoxins historically have served as valuable tools for identification, purification, and functional characterization of voltage-dependent ion channels. In particular, toxins from scorpions, sea anemones and cone snails were at the forefront of work aimed at illuminating the three-dimensional architecture of sodium channels. To date, at least six different receptor binding sites have been identified and--most of them--structurally assigned in terms of protein sequence and spatial disposition. Recent work on Australian funnel-web spiders identified certain peptidic ingredients as being responsible for the neurotoxicity of the crude venom. These peptides, termed delta-atracotoxins (delta-ACTX), consist of 42 amino acids and bind to voltage-gated sodium channels in the same way as classical scorpion alpha-toxins. According to the 'voltage-sensor trapping model' proposed in the literature, delta-ACTX isoforms interact with the voltage sensor S4 transmembrane segment of alpha-subunit domain IV, thereby preventing its normal outward movement and concurrent conformational changes required for inactivation of the channel. As consequence prolonged action potentials at autonomic or somatic synapses induce massive transmitter release, resulting in clinical correlates of neuroexcitation (e.g., muscle fasciculation, spasms, paresthesia, tachycardia, diaphoresis, etc.). On the other hand, the major neurotoxin isolated from black widow spiders, alpha-latrotoxin (alpha-LTX), represents a 132 kDa protein consisting of a unique N-terminal sequence and a C-terminal part harboring multiple ankyrin-like repeats. Upon binding to one of its specific presynaptic receptors, alpha-LTX has been shown to tetramerize under physiological conditions to form Ca2+-permeable pores in presynaptic membranes. The molecular model worked out during recent years separates two distinguishable receptor-mediated effects. According to current knowledge, binding of the N terminus of alpha-LTX at one of its specific receptors either triggers intracellular signaling cascades, resulting in phospholipase C-mediated mobilization of presynaptic Ca2+ stores, or leads to the formation of tetrameric pore complexes, allowing extracellular Ca2+ to enter the presynaptic terminal. Alpha-LTX-triggered exocytosis and fulminant transmitter release at autonomic synapses may then provoke a clinical syndrome referred to as 'latrodectism', characterized by local and incapacitating pain, diaphoresis, muscle fasciculation, tremor, anxiety, and so forth. The present review aims at providing a short introduction into some of the exciting molecular effects induced by neurotoxins isolated from black widow and funnel-web spiders.

Low-energy cardioversion of spontaneous atrial fibrillation. Immediate and long-term results.

PubMed

Lévy, S; Ricard, P; Gueunoun, M; Yapo, F; Trigano, J; Mansouri, C; Paganelli, F

1997-07-01

Recent studies have suggested that induced atrial fibrillation (AF) could be successfully terminated by using a two-catheter electrode system and low energy (< 400 V). This study evaluated the efficacy and safety of low-energy cardioversion in spontaneous chronic and paroxysmal AF. Forty-two consecutive patients with spontaneous AF underwent low-energy electrical cardioversion. AF was chronic (> or = 1 month) with a mean duration of 9 +/- 19 months in 28 patients (group I) or paroxysmal with a history of recurrent attacks and a mean duration of the present episode of 7 +/- 16 days in 14 patients (group II). An underlying heart disease was present in 28 patients. A 3/3-ms biphasic shock was delivered between catheters positioned in the right atrium and the coronary sinus in 32 patients. In 10 patients, the left pulmonary artery branch was used. The catheters were connected to a custom external defibrillator. The shocks were synchronized to the R wave. Following a test shock of 60 V, the energy was increased in 40-V steps until a maximum of 400 V or restoration of sinus rhythm. Sinus rhythm was restored in 22 of the 28 patients (78%) of group I by using a mean leading-edge voltage of 297 +/- 57 V (mean energy 3.3 +/- 1.3 J) and in 11 of 14 patients (78%) of group II by using a mean leading-edge voltage of 223 +/- 41 V (mean energy, 1.8 +/- 0.7 J). The energy required for terminating chronic AF was significantly (P < .001) higher than that required for terminating paroxysmal AF. Among the other variables studied, the duration of AF significantly affected the successful voltage. Ventricular proarrhythmia occurred in 1 patient with atrial flutter due to an unsynchronized shock. Of the 22 patients of group I in whom sinus rhythm was restored, 14 (63%) remained in sinus rhythm with a mean follow-up of 9 +/- 3 months. Pain level showed a good correlation with increasing voltage. However, a marked inter-individual variation was noted. Atrial defibrillation using low energy between two intracardiac catheters with an electrical field between the right and left atria and the protocol used is feasible in patients with persistent spontaneous AF. The technique is safe provided synchronization to the R wave is achieved. A low recurrence rate of AF was seen in patients in whom sinus rhythm was restored.

Motor power factor controller with a reduced voltage starter

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1981-01-01

A power factor type motor controller is disclosed in which the conventional power factor constant voltage command signal is replaced during a starting interval with a graduated control voltage. This continuation-impart of a pending patent application (Serial No. 199, 765: Three Phase Factor Controller) provides a means for modifying the operation of the system for a motor start-up interval of 5 to 30 second. Using a ramp generators, an initial ramp-like signal replaces a constant power factor signal supplied by a potentiometer. The ramp-like signal is applied to a 15 terminal where it is summed with an operating power factor signal from phase detectors in order to obtain a control signal for ultimately controlling SCR devices. The SCR devices are turned on at an advancing rate with time responsive to the combination signal described rather than simply a function of a ramp-like signal alone.

Method and apparatus for in-situ characterization of energy storage and energy conversion devices

DOEpatents

Christophersen, Jon P [Idaho Falls, ID; Motloch, Chester G [Idaho Falls, ID; Morrison, John L [Butte, MT; Albrecht, Weston [Layton, UT

2010-03-09

Disclosed are methods and apparatuses for determining an impedance of an energy-output device using a random noise stimulus applied to the energy-output device. A random noise signal is generated and converted to a random noise stimulus as a current source correlated to the random noise signal. A bias-reduced response of the energy-output device to the random noise stimulus is generated by comparing a voltage at the energy-output device terminal to an average voltage signal. The random noise stimulus and bias-reduced response may be periodically sampled to generate a time-varying current stimulus and a time-varying voltage response, which may be correlated to generate an autocorrelated stimulus, an autocorrelated response, and a cross-correlated response. Finally, the autocorrelated stimulus, the autocorrelated response, and the cross-correlated response may be combined to determine at least one of impedance amplitude, impedance phase, and complex impedance.

Passive Resonant Bidirectional Converter with Galvanic Barrier

NASA Technical Reports Server (NTRS)

Rosenblad, Nathan S. (Inventor)

2014-01-01

A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

Action Potential Dynamics in Fine Axons Probed with an Axonally Targeted Optical Voltage Sensor.

PubMed

Ma, Yihe; Bayguinov, Peter O; Jackson, Meyer B

2017-01-01

The complex and malleable conduction properties of axons determine how action potentials propagate through extensive axonal arbors to reach synaptic terminals. The excitability of axonal membranes plays a major role in neural circuit function, but because most axons are too thin for conventional electrical recording, their properties remain largely unexplored. To overcome this obstacle, we used a genetically encoded hybrid voltage sensor (hVOS) harboring an axonal targeting motif. Expressing this probe in transgenic mice enabled us to monitor voltage changes optically in two populations of axons in hippocampal slices, the large axons of dentate granule cells (mossy fibers) in the stratum lucidum of the CA3 region and the much finer axons of hilar mossy cells in the inner molecular layer of the dentate gyrus. Action potentials propagated with distinct velocities in each type of axon. Repetitive firing broadened action potentials in both populations, but at an intermediate frequency the degree of broadening differed. Repetitive firing also attenuated action potential amplitudes in both mossy cell and granule cell axons. These results indicate that the features of use-dependent action potential broadening, and possible failure, observed previously in large nerve terminals also appear in much finer unmyelinated axons. Subtle differences in the frequency dependences could influence the propagation of activity through different pathways to excite different populations of neurons. The axonally targeted hVOS probe used here opens up the diverse repertoire of neuronal processes to detailed biophysical study.

Cryogenic Pound Circuits for Cryogenic Sapphire Oscillators

NASA Technical Reports Server (NTRS)

Dick, G. John; Wang, Rabi

2006-01-01

Two modern cryogenic variants of the Pound circuit have been devised to increase the frequency stability of microwave oscillators that include cryogenic sapphire-filled cavity resonators. The original Pound circuit is a microwave frequency discriminator that provides feedback to stabilize a voltage-controlled microwave oscillator with respect to an associated cavity resonator. In the present cryogenic Pound circuits, the active microwave devices are implemented by use of state-of-the-art commercially available tunnel diodes that exhibit low flicker noise (required for high frequency stability) and function well at low temperatures and at frequencies up to several tens of gigahertz. While tunnel diodes are inherently operable as amplitude detectors and amplitude modulators, they cannot, by themselves, induce significant phase modulation. Therefore, each of the present cryogenic Pound circuits includes passive circuitry that transforms the AM into the required PM. Each circuit also contains an AM detector that is used to sample the microwave signal at the input terminal of the high-Q resonator for the purpose of verifying the desired AM null at this point. Finally, each circuit contains a Pound signal detector that puts out a signal, at the modulation frequency, having an amplitude proportional to the frequency error in the input signal. High frequency stability is obtained by processing this output signal into feedback to a voltage-controlled oscillator to continuously correct the frequency error in the input signal.

Design and test of current limiting modules using YBCO-coated conductors

NASA Astrophysics Data System (ADS)

Schmidt, W.; Gamble, B.; Kraemer, H.-P.; Madura, D.; Otto, A.; Romanosky, W.

2010-01-01

Within the cooperation between American Superconductor Corporation (AMSC) and Siemens Corporate Technology we have investigated the fault current limiting performance of YBCO-coated conductors (also called second-generation or 2G HTS wires) stabilized with stainless steel laminates. Design rules for the length and width of the wire depending on utility grid requirements have been established. Bifilar coils have been manufactured and tested with a typical limitation period of 50 ms under stepwise increasing voltage loads to determine the maximum temperature the wires can withstand without degradation. Coils have been assembled into limiter modules demonstrating uniform tripping of the individual coils and recovery within seconds. At present this cooperation is proceeding within a joint project funded by the US Department of Energy (DOE) that encompasses the design, construction and testing of a 115 kV FCL for power transmission within a time frame of 4-5 years, and additional partners. Besides AMSC and Siemens, Nexans contributes the high voltage terminations and Los Alamos National Lab investigates the ac losses. Installation and testing are planned for a Southern California Edison substation. The module planned for the transmission voltage application consists of 63 horizontally arranged coils connected in parallel and series to account for a rated current of 1.2 kArms and voltage of 31 kVrms plus margins. The rated voltage of the module is considerably lower than the line to ground voltage in the 115 kV grid owing to our shunted limiter concept. The shunt reactor connected in parallel to the module outside the cryostat allows for adjustment of the limited current and reduces voltage drop across the module in case of a fault. The fault current reduction ratio is 42% for our present design. A subscale module comprising six full-size coils has been assembled and tested recently to validate the coil performance and coil winding technique. The module had a critical current of 425 ADC and a nominal power of 2.52 MV A at 77 K. A complete series of tests with applied voltage up to 8.4 kVrms, prospective short circuit current up to 26.6 kArms and variation of phase angle at initiation of the fault has been performed. After more than 40 switching tests the critical current of the module remained unchanged, indicating that no degradation of the wire occurred.

A new approach for two-terminal electronic memory devices - Storing information on silicon nanowires

NASA Astrophysics Data System (ADS)

Saranti, Konstantina; Alotaibi, Sultan; Paul, Shashi

2016-06-01

The work described in this paper focuses on the utilisation of silicon nanowires as the information storage element in flash-type memory devices. Silicon nanostructures have attracted attention due to interesting electrical and optical properties, and their potential integration into electronic devices. A detailed investigation of the suitability of silicon nanowires as the charge storage medium in two-terminal non-volatile memory devices are presented in this report. The deposition of the silicon nanostructures was carried out at low temperatures (less than 400 °C) using a previously developed a novel method within our research group. Two-terminal non-volatile (2TNV) memory devices and metal-insulator-semiconductor (MIS) structures containing the silicon nanowires were fabricated and an in-depth study of their characteristics was carried out using current-voltage and capacitance techniques.

Ca(2+) influx and neurotransmitter release at ribbon synapses.

PubMed

Cho, Soyoun; von Gersdorff, Henrique

2012-01-01

Ca(2+) influx through voltage-gated Ca(2+) channels triggers the release of neurotransmitters at presynaptic terminals. Some sensory receptor cells in the peripheral auditory and visual systems have specialized synapses that express an electron-dense organelle called a synaptic ribbon. Like conventional synapses, ribbon synapses exhibit SNARE-mediated exocytosis, clathrin-mediated endocytosis, and short-term plasticity. However, unlike non-ribbon synapses, voltage-gated L-type Ca(2+) channel opening at ribbon synapses triggers a form of multiquantal release that can be highly synchronous. Furthermore, ribbon synapses appear to be specialized for fast and high throughput exocytosis controlled by graded membrane potential changes. Here we will discuss some of the basic aspects of synaptic transmission at different types of ribbon synapses, and we will emphasize recent evidence that auditory and retinal ribbon synapses have marked differences. This will lead us to suggest that ribbon synapses are specialized for particular operating ranges and frequencies of stimulation. We propose that different types of ribbon synapses transfer diverse rates of sensory information by expressing a particular repertoire of critical components, and by placing them at precise and strategic locations, so that a continuous supply of primed vesicles and Ca(2+) influx leads to fast, accurate, and ongoing exocytosis. Copyright © 2012 Elsevier Ltd. All rights reserved.

Neural network method for lossless two-conductor transmission line equations based on the IELM algorithm

NASA Astrophysics Data System (ADS)

Yang, Yunlei; Hou, Muzhou; Luo, Jianshu; Liu, Taohua

2018-06-01

With the increasing demands for vast amounts of data and high-speed signal transmission, the use of multi-conductor transmission lines is becoming more common. The impact of transmission lines on signal transmission is thus a key issue affecting the performance of high-speed digital systems. To solve the problem of lossless two-conductor transmission line equations (LTTLEs), a neural network model and algorithm are explored in this paper. By selecting the product of two triangular basis functions as the activation function of hidden layer neurons, we can guarantee the separation of time, space, and phase orthogonality. By adding the initial condition to the neural network, an improved extreme learning machine (IELM) algorithm for solving the network weight is obtained. This is different to the traditional method for converting the initial condition into the iterative constraint condition. Calculation software for solving the LTTLEs based on the IELM algorithm is developed. Numerical experiments show that the results are consistent with those of the traditional method. The proposed neural network algorithm can find the terminal voltage of the transmission line and also the voltage of any observation point. It is possible to calculate the value at any given point by using the neural network model to solve the transmission line equation.

Four-terminal connector for measuring resistance of a pyrotechnic initiator

NASA Technical Reports Server (NTRS)

Robinson, Robert L. (Inventor); Graves, Thomas J. (Inventor); Hoffman, III, William C. (Inventor)

1989-01-01

A four-terminal electrical connector device (40) for testing and measuring unknown resistances of initiators (11) used for starting pyrotechnic events aboard a Space Transportation System. The testing device minimizes contact resistance degradation effects and so improves the reliability of resistance measurement taken with the device. Separate and independent voltage sensing (19) and current supply (20) circuits each includes a pair of socket contacts (13-16) for mating engagement with the pins (17,18) of the initiator. The unknown resistance that is measured by the device is the resistance of the bridgewire (23) of the initiator which is required to be between 0.95 and 1.15 ohms.

30 CFR 77.800 - High-voltage circuits; circuit breakers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... devices to provide protection against under voltage, grounded phase, short circuit and overcurrent. High... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage circuits; circuit breakers. 77.800... COAL MINES Surface High-Voltage Distribution § 77.800 High-voltage circuits; circuit breakers. High...

Improved Transient and Steady-State Performances of Series Resonant ZCS High-Frequency Inverter-Coupled Voltage Multiplier Converter with Dual Mode PFM Control Scheme

NASA Astrophysics Data System (ADS)

Chu, Enhui; Gamage, Laknath; Ishitobi, Manabu; Hiraki, Eiji; Nakaoka, Mutsuo

The A variety of switched-mode high voltage DC power supplies using voltage-fed type or current-fed type high-frequency transformer resonant inverters using MOS gate bipolar power transistors; IGBTs have been recently developed so far for a medical-use X-ray high power generator. In general, the high voltage high power X-ray generator using voltage-fed high frequency inverter with a high voltage transformer link has to meet some performances such as (i) short rising period in start transient of X-ray tube voltage (ii) no overshoot transient response in tube voltage, (iii) minimized voltage ripple in periodic steady-state under extremely wide load variations and filament heater current fluctuation conditions of the X-ray tube. This paper presents two lossless inductor snubber-assisted series resonant zero current soft switching high-frequency inverter using a diode-capacitor ladder type voltage multiplier called Cockcroft-Walton circuit, which is effectively implemented for a high DC voltage X-ray power generator. This DC high voltage generator which incorporates pulse frequency modulated series resonant inverter using IGBT power module packages is based on the operation principle of zero current soft switching commutation scheme under discontinuous resonant current and continuous resonant current transition modes. This series capacitor compensated for transformer resonant power converter with a high frequency transformer linked voltage boost multiplier can efficiently work a novel selectively-changed dual mode PFM control scheme in order to improve the start transient and steady-state response characteristics and can completely achieve stable zero current soft switching commutation tube filament current dependent for wide load parameter setting values with the aid of two lossless inductor snubbers. It is proved on the basis of simulation and experimental results in which a simple and low cost control implementation based on selectively-changed dual-mode PFM for high-voltage X-ray DC-DC power converter with a voltage multiplier strategy has some specified voltage pattern tracking voltage response performances under rapid rising time and no overshoot in start transient tube voltage as well as the minimized steady-state voltage ripple in tube voltage.

A BK (Slo1) channel journey from molecule to physiology

PubMed Central

Contreras, Gustavo F; Castillo, Karen; Enrique, Nicolás; Carrasquel-Ursulaez, Willy; Castillo, Juan Pablo; Milesi, Verónica; Neely, Alan; Alvarez, Osvaldo; Ferreira, Gonzalo; González, Carlos; Latorre, Ramón

2013-01-01

Calcium and voltage-activated potassium (BK) channels are key actors in cell physiology, both in neuronal and non-neuronal cells and tissues. Through negative feedback between intracellular Ca2+ and membrane voltage, BK channels provide a damping mechanism for excitatory signals. Molecular modulation of these channels by alternative splicing, auxiliary subunits and post-translational modifications showed that these channels are subjected to many mechanisms that add diversity to the BK channel α subunit gene. This complexity of interactions modulates BK channel gating, modifying the energetic barrier of voltage sensor domain activation and channel opening. Regions for voltage as well as Ca2+ sensitivity have been identified, and the crystal structure generated by the 2 RCK domains contained in the C-terminal of the channel has been described. The linkage of these channels to many intracellular metabolites and pathways, as well as their modulation by extracellular natural agents, has been found to be relevant in many physiological processes. This review includes the hallmarks of BK channel biophysics and its physiological impact on specific cells and tissues, highlighting its relationship with auxiliary subunit expression. PMID:24025517

Low power, scalable multichannel high voltage controller

DOEpatents

Stamps, James Frederick [Livermore, CA; Crocker, Robert Ward [Fremont, CA; Yee, Daniel Dadwa [Dublin, CA; Dils, David Wright [Fort Worth, TX

2006-03-14

A low voltage control circuit is provided for individually controlling high voltage power provided over bus lines to a multitude of interconnected loads. An example of a load is a drive for capillary channels in a microfluidic system. Control is distributed from a central high voltage circuit, rather than using a number of large expensive central high voltage circuits to enable reducing circuit size and cost. Voltage is distributed to each individual load and controlled using a number of high voltage controller channel switches connected to high voltage bus lines. The channel switches each include complementary pull up and pull down photo isolator relays with photo isolator switching controlled from the central high voltage circuit to provide a desired bus line voltage. Switching of the photo isolator relays is further controlled in each channel switch using feedback from a resistor divider circuit to maintain the bus voltage swing within desired limits. Current sensing is provided using a switched resistive load in each channel switch, with switching of the resistive loads controlled from the central high voltage circuit.

Low power, scalable multichannel high voltage controller

DOEpatents

Stamps, James Frederick [Livermore, CA; Crocker, Robert Ward [Fremont, CA; Yee, Daniel Dadwa [Dublin, CA; Dils, David Wright [Fort Worth, TX

2008-03-25

A low voltage control circuit is provided for individually controlling high voltage power provided over bus lines to a multitude of interconnected loads. An example of a load is a drive for capillary channels in a microfluidic system. Control is distributed from a central high voltage circuit, rather than using a number of large expensive central high voltage circuits to enable reducing circuit size and cost. Voltage is distributed to each individual load and controlled using a number of high voltage controller channel switches connected to high voltage bus lines. The channel switches each include complementary pull up and pull down photo isolator relays with photo isolator switching controlled from the central high voltage circuit to provide a desired bus line voltage. Switching of the photo isolator relays is further controlled in each channel switch using feedback from a resistor divider circuit to maintain the bus voltage swing within desired limits. Current sensing is provided using a switched resistive load in each channel switch, with switching of the resistive loads controlled from the central high voltage circuit.

Robust tracking control of an IPMC actuator using nonsingular terminal sliding mode

NASA Astrophysics Data System (ADS)

Khawwaf, Jasim; Zheng, Jinchuan; Lu, Renquan; Al-Ghanimi, Ali; Kazem, Bahaa I.; Man, Zhihong

2017-09-01

Ionic polymer metal composite (IPMC) is a highly innovative material that has recently gained attention in many fields such as medical, biomimetic, and micro/nano underwater applications. The main characteristic of IPMC lies in its ability to achieve a large deflection under a fairly low driving voltage. Moreover, its agile, light weight, noiseless and flexible features render it well suited for certain specific applications. Like other smart materials, such as piezoelectric ceramics, IPMC could be used in actuators or sensors. In this paper, we study the application of IPMC as an actuator for underwater use. The goal is to develop a robust feedback controller for the IPMC actuator to track a desired reference whilst dealing with the uncertainties due to the inherent actuator nonlinearity, external disturbance or the variations of working environment. To this end, we first present a nominal model of the IPMC actuator through experimental identification. Next, a nonsingular terminal sliding mode controller is proposed. Lastly, experimental studies are conducted to verify the tracking accuracy and robustness of the designed controller.

Effective D-A-D type chromophore of fumaronitrile-core and terminal alkylated bithiophene for solution-processed small molecule organic solar cells.

PubMed

Nazim, M; Ameen, Sadia; Seo, Hyung-Kee; Shin, Hyung Shik

2015-06-12

A new and novel organic π-conjugated chromophore (named as RCNR) based on fumaronitrile-core acceptor and terminal alkylated bithiophene was designed, synthesized and utilized as an electron-donor material for the solution-processed fabrication of bulk-heterojunction (BHJ) small molecule organic solar cells (SMOSCs). The synthesized organic chromophore exhibited a broad absorption peak near green region and strong emission peak due to the presence of strong electron-withdrawing nature of two nitrile (-CN) groups of fumaronitrile acceptor. The highest occupied molecular orbital (HOMO) energy level of -5.82 eV and the lowest unoccupied molecular orbital (LUMO) energy level of -3.54 eV were estimated for RCNR due to the strong electron-accepting tendency of -CN groups. The fabricated SMOSC devices with RCNR:PC60BM (1:3, w/w) active layer exhibited the reasonable power conversion efficiency (PCE) of ~2.69% with high short-circuit current density (JSC) of ~9.68 mA/cm(2) and open circuit voltage (VOC) of ~0.79 V.

Effective D-A-D type chromophore of fumaronitrile-core and terminal alkylated bithiophene for solution-processed small molecule organic solar cells

PubMed Central

Nazim, M.; Ameen, Sadia; Seo, Hyung-Kee; Shin, Hyung Shik

2015-01-01

A new and novel organic π-conjugated chromophore (named as RCNR) based on fumaronitrile-core acceptor and terminal alkylated bithiophene was designed, synthesized and utilized as an electron-donor material for the solution-processed fabrication of bulk-heterojunction (BHJ) small molecule organic solar cells (SMOSCs). The synthesized organic chromophore exhibited a broad absorption peak near green region and strong emission peak due to the presence of strong electron-withdrawing nature of two nitrile (–CN) groups of fumaronitrile acceptor. The highest occupied molecular orbital (HOMO) energy level of –5.82 eV and the lowest unoccupied molecular orbital (LUMO) energy level of –3.54 eV were estimated for RCNR due to the strong electron-accepting tendency of –CN groups. The fabricated SMOSC devices with RCNR:PC60BM (1:3, w/w) active layer exhibited the reasonable power conversion efficiency (PCE) of ~2.69% with high short-circuit current density (JSC) of ~9.68 mA/cm2 and open circuit voltage (VOC) of ~0.79 V. PMID:26066557

30 CFR 77.810 - High-voltage equipment; grounding.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage equipment; grounding. 77.810... COAL MINES Surface High-Voltage Distribution § 77.810 High-voltage equipment; grounding. Frames, supporting structures, and enclosures of stationary, portable, or mobile high-voltage equipment shall be...

Modular high voltage power supply for chemical analysis

DOEpatents

Stamps, James F [Livermore, CA; Yee, Daniel D [Dublin, CA

2007-01-09

A high voltage power supply for use in a system such as a microfluidics system, uses a DC--DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC--DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

Modular high voltage power supply for chemical analysis

DOEpatents

Stamps, James F [Livermore, CA; Yee, Daniel D [Dublin, CA

2010-05-04

A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

Modular high voltage power supply for chemical analysis

DOEpatents

Stamps, James F [Livermore, CA; Yee, Daniel D [Dublin, CA

2008-07-15

A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

C-Terminal β9-Strand of the Cyclic Nucleotide-Binding Homology Domain Stabilizes Activated States of Kv11.1 Channels

PubMed Central

Ng, Chai Ann; Ke, Ying; Perry, Matthew D.; Tan, Peter S.; Hill, Adam P.; Vandenberg, Jamie I.

2013-01-01

Kv11.1 potassium channels are important for regulation of the normal rhythm of the heartbeat. Reduced activity of Kv11.1 channels causes long QT syndrome type 2, a disorder that increases the risk of cardiac arrhythmias and sudden cardiac arrest. Kv11.1 channels are members of the KCNH subfamily of voltage-gated K+ channels. However, they also share many similarities with the cyclic nucleotide gated ion channel family, including having a cyclic nucleotide-binding homology (cNBH) domain. Kv11.1 channels, however, are not directly regulated by cyclic nucleotides. Recently, crystal structures of the cNBH domain from mEAG and zELK channels, both members of the KCNH family of voltage-gated potassium channels, revealed that a C-terminal β9-strand in the cNBH domain occupied the putative cyclic nucleotide-binding site thereby precluding binding of cyclic nucleotides. Here we show that mutations to residues in the β9-strand affect the stability of the open state relative to the closed state of Kv11.1 channels. We also show that disrupting the structure of the β9-strand reduces the stability of the inactivated state relative to the open state. Clinical mutations located in this β9-strand result in reduced trafficking efficiency, which suggests that binding of the C-terminal β9-strand to the putative cyclic nucleotide-binding pocket is also important for assembly and trafficking of Kv11.1 channels. PMID:24204727

Kinetics of Inhibitory Feedback from Horizontal Cells to Photoreceptors: Implications for an Ephaptic Mechanism

PubMed Central

Warren, Ted J.; Van Hook, Matthew J.; Tranchina, Daniel

2016-01-01

Inhibitory feedback from horizontal cells (HCs) to cones generates center-surround receptive fields and color opponency in the retina. Mechanisms of HC feedback remain unsettled, but one hypothesis proposes that an ephaptic mechanism may alter the extracellular electrical field surrounding photoreceptor synaptic terminals, thereby altering Ca2+ channel activity and photoreceptor output. An ephaptic voltage change produced by current flowing through open channels in the HC membrane should occur with no delay. To test for this mechanism, we measured kinetics of inhibitory feedback currents in Ambystoma tigrinum cones and rods evoked by hyperpolarizing steps applied to synaptically coupled HCs. Hyperpolarizing HCs stimulated inward feedback currents in cones that averaged 8–9 pA and exhibited a biexponential time course with time constants averaging 14–17 ms and 120–220 ms. Measurement of feedback-current kinetics was limited by three factors: (1) HC voltage-clamp speed, (2) cone voltage-clamp speed, and (3) kinetics of Ca2+ channel activation or deactivation in the photoreceptor terminal. These factors totaled ∼4–5 ms in cones meaning that the true fast time constants for HC-to-cone feedback currents were 9–13 ms, slower than expected for ephaptic voltage changes. We also compared speed of feedback to feedforward glutamate release measured at the same cone/HC synapses and found a latency for feedback of 11–14 ms. Inhibitory feedback from HCs to rods was also significantly slower than either measurement kinetics or feedforward release. The finding that inhibitory feedback from HCs to photoreceptors involves a significant delay indicates that it is not due to previously proposed ephaptic mechanisms. SIGNIFICANCE STATEMENT Lateral inhibitory feedback from horizontal cells (HCs) to photoreceptors creates center-surround receptive fields and color-opponent interactions. Although underlying mechanisms remain unsettled, a longstanding hypothesis proposes that feedback is due to ephaptic voltage changes that regulate photoreceptor synaptic output by altering Ca2+ channel activity. Ephaptic processes should occur with no delay. We measured kinetics of inhibitory feedback currents evoked in photoreceptors with voltage steps applied to synaptically coupled HCs and found that feedback is too slow to be explained by ephaptic voltage changes generated by current flowing through continuously open channels in HC membranes. By eliminating the proposed ephaptic mechanism for HC feedback regulation of photoreceptor Ca2+ channels, our data support earlier proposals that synaptic cleft pH changes are more likely responsible. PMID:27683904

30 CFR 77.804 - High-voltage trailing cables; minimum design requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage trailing cables; minimum design... OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.804 High-voltage trailing cables; minimum design requirements. (a) High-voltage trailing cables used in resistance grounded systems shall be...

30 CFR 75.833 - Handling high-voltage trailing cables.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Handling high-voltage trailing cables. 75.833... High-Voltage Longwalls § 75.833 Handling high-voltage trailing cables. (a) Cable handling. (1) Miners must not handle energized trailing cables unless they are wearing high-voltage insulating gloves, which...

30 CFR 77.804 - High-voltage trailing cables; minimum design requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false High-voltage trailing cables; minimum design... OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.804 High-voltage trailing cables; minimum design requirements. (a) High-voltage trailing cables used in resistance grounded systems shall be...

30 CFR 77.804 - High-voltage trailing cables; minimum design requirements.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false High-voltage trailing cables; minimum design... OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.804 High-voltage trailing cables; minimum design requirements. (a) High-voltage trailing cables used in resistance grounded systems shall be...

30 CFR 77.804 - High-voltage trailing cables; minimum design requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false High-voltage trailing cables; minimum design... OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.804 High-voltage trailing cables; minimum design requirements. (a) High-voltage trailing cables used in resistance grounded systems shall be...

Matrix Converter Interface for a Wind Energy Conversion System: Issues and Limitations

NASA Astrophysics Data System (ADS)

Patki, Chetan; Agarwal, Vivek

2009-08-01

Variable speed grid connected wind energy systems sometimes involve AC-AC power electronic interface between the generator and the grid. Matrix converter is an attractive option for such applications. Variable speed of the wind generator demands variable voltage variable frequency at the generator terminal. Matrix converter is used in this work to generate such a supply. Also, matrix converter can be appropriately controlled to compensate the grid for non-linear, reactive loads. However, any change of power factor on the grid side reflects on the voltage magnitude on the wind generator side. It is highlighted that this may contradict the maximum power point tracking control requirements. All the results of this work are presented.

Control of Analyte Electrolysis in Electrospray Ionization Mass Spectrometry Using Repetitively Pulsed High Voltage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kertesz, Vilmos; Van Berkel, Gary J

2011-01-01

Analyte electrolysis using a repetitively pulsed high voltage ion source was investigated and compared to that using a regular, continuously operating direct current high voltage ion source in electrospray ionization mass spectrometry. The extent of analyte electrolysis was explored as a function of the length and frequency of the high voltage pulse using the model compound reserpine in positive ion mode. Using +5 kV as the maximum high voltage amplitude, reserpine was oxidized to its 2, 4, 6 and 8-electron oxidation products when direct current high voltage was employed. In contrast, when using a pulsed high voltage, oxidation of reserpinemore » was eliminated by employing the appropriate high voltage pulse length and frequency. This effect was caused by inefficient mass transport of the analyte to the electrode surface during the duration of the high voltage pulse and the subsequent relaxation of the emitter electrode/ electrolyte interface during the time period when the high voltage was turned off. This mode of ESI source operation allows for analyte electrolysis to be quickly and simply switched on or off electronically via a change in voltage pulse variables.« less

Influence of the Terminal Electron Donor in D-D-π-A Organic Dye-Sensitized Solar Cells: Dithieno[3,2-b:2',3'-d]pyrrole versus Bis(amine).

PubMed

Dai, Panpan; Yang, Lin; Liang, Mao; Dong, Huanhuan; Wang, Peng; Zhang, Chunyao; Sun, Zhe; Xue, Song

2015-10-14

With respect to the electron-withdrawing acceptors of D-A-π-A organic dyes, reports on the second electron-donating donors for D-D-π-A organic dyes are very limited. Both of the dyes have attracted significant attention in the field of dye-sensitized solar cells (DSCs). In this work, four new D-D-π-A organic dyes with dithieno[3,2-b:2',3'-d]pyrrole (DTP) or bis(amine) donor have been designed and synthesized for a investigation of the influence of the terminal electron donor in D-D-π-A organic dye-sensitized solar cells. It is found that DTP is a promising building block as the terminal electron donor when introduced in the dithiophenepyrrole direction, but not just a good bridge, which exhibits several characteristics: (i) efficiently increasing the maximum molar absorption coefficient and extending the absorption bands; (ii) showing stronger charge transfer interaction as compared with the pyrrole direction; (iii) beneficial to photocurrent generation of DSCs employing cobalt electrolytes. DSCs based on M45 with the Co-phen electrolyte exhibit good light-to-electric energy conversion efficiencies as high as 9.02%, with a short circuit current density (JSC) of 15.3 mA cm(-2), open circuit voltage (VOC) of 867 mV and fill factor (FF) of 0.68 under AM 1.5 illumination (100 mW cm(-2)). The results demonstrate that N,S-heterocycles such as DTP unit could be promising candidates for application in highly efficient DSCs employing cobalt electrolyte.

Low Power, High Voltage Power Supply with Fast Rise/Fall Time

NASA Technical Reports Server (NTRS)

Bearden, Douglas B. (Inventor)

2007-01-01

A low power, high voltage power supply system includes a high voltage power supply stage and a preregulator for programming the power supply stage so as to produce an output voltage which is a predetermined fraction of a desired voltage level. The power supply stage includes a high voltage, voltage doubler stage connected to receive the output voltage from the preregulator and for, when activated, providing amplification of the output voltage to the desired voltage level. A first feedback loop is connected between the output of the preregulator and an input of the preregulator while a second feedback loop is connected between the output of the power supply stage and the input of the preregulator.

Low power, high voltage power supply with fast rise/fall time

NASA Technical Reports Server (NTRS)

Bearden, Douglas B. (Inventor)

2007-01-01

A low power, high voltage power supply system includes a high voltage power supply stage and a preregulator for programming the power supply stage so as to produce an output voltage which is a predetermined fraction of a desired voltage level. The power supply stage includes a high voltage, voltage doubler stage connected to receive the output voltage from the preregulator and for, when activated, providing amplification of the output voltage to the desired voltage level. A first feedback loop is connected between the output of the preregulator and an input of the preregulator while a second feedback loop is connected between the output of the power supply stage and the input of the preregulator.

Voltage tunable two-color superlattice infrared photodetectors

NASA Astrophysics Data System (ADS)

Majumdar, Amlan; Choi, Kwong-Kit; Reno, John L.; Tsui, Daniel C.

2004-11-01

We present the design and fabrication of voltage tunable two-color superlattice infrared photodetectors (SLIPs), where the detection wavelength switches from the long-wavelength infrared (LWIR) range to the mid-wavelength infrared (MWIR) range upon reversing the polarity of applied bias. The photoactive region of these detectors contains multiple periods of two distinct short-period SLs that are designed for MWIR and LWIR detection. The voltage tunable operation is achieved by using two types of thick blocking barriers between adjacent SLs - undoped barriers on one side for low energy electrons and heavily-doped layers on the other side for high energy electrons. We grew two SLIP structures by molecular beam epitaxy. The first one consists of two AlGaAs/GaAs SLs with the detection range switching from the 7-11 μm band to the 4-7 μm range on reversing the bias polarity. The background-limited temperature is 55 and 80 K for LWIR and MWIR detection, respectively. The second structure comprises of strained InGaAs/GaAs/AlGaAs SLs and AlGaAs/GaAs SLs. The detection range of this SLIP changes from the 8-12 μm band to the 3-5 μm band on switching the bias polarity. The background-limited temperature is 70 and 110 K for LWIR and MWIR detection, respectively. This SLIP is the first ever voltage tunable MWIR/LWIR detector with performance comparable to those of one-color quantum-well infrared detectors designed for the respective wavelength ranges. We also demonstrate that the corrugated light coupling scheme, which enables normal-incidence absorption, is suitable for the two-color SLIPs. Since these SLIPs are two-terminal devices, they can be used with the corrugated geometry for the production of low-cost large-area two-color focal plane arrays.

A triple hybrid micropower generator with simultaneous multi-mode energy harvesting

NASA Astrophysics Data System (ADS)

Uluşan, H.; Chamanian, S.; Pathirana, W. P. M. R.; Zorlu, Ö.; Muhtaroğlu, A.; Külah, H.

2018-01-01

This study presents a triple hybrid energy harvesting system that combines harvested power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters into a single DC supply. A power management circuit is designed and implemented in 180 nm standard CMOS technology based on the distinct requirements of each harvester, and is terminated with a Schottky diode to avoid reverse current flow. The system topology hence supports simultaneous power generation and delivery from low and high frequency vibrations as well as temperature differences in the environment. The ultra-low DC voltage harvested from TE generator is boosted with a cross-coupled charge-pump driven by an LC oscillator with fully-integrated center-tapped differential inductors. The EM harvester output was rectified with a self-powered and low drop-out AC/DC doubler circuit. The PZT interface electronics benefits from peak-to-peak cycle of the harvested voltage through a negative voltage converter followed by synchronous power extraction and DC-to-DC conversion through internal switches, and an external inductor. The hybrid system was tested with a wearable in-house EM energy harvester placed wrist of a jogger, a commercial low volume PZT harvester, and DC supply as the TE generator output. The system generates more than 1.2 V output for load resistances higher than 50 kΩ, which corresponds to 24 μW to power wearable sensors. Simultaneous multi-mode operation achieves higher voltage and power compared to stand-alone harvesting circuits, and generates up to 110 μW of output power. This is the first hybrid harvester circuit that simultaneously extracts energy from three independent sources, and delivers a single DC output.

30 CFR 75.705 - Work on high-voltage lines; deenergizing and grounding.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Work on high-voltage lines; deenergizing and... Work on high-voltage lines; deenergizing and grounding. [Statutory Provisions] High-voltage lines, both..., except that repairs may be permitted, in the case of energized surface high-voltage lines, if such...

30 CFR 75.813 - High-voltage longwalls; scope.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage longwalls; scope. 75.813 Section 75.813 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.813 High-voltage...

30 CFR 75.813 - High-voltage longwalls; scope.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false High-voltage longwalls; scope. 75.813 Section 75.813 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution High-Voltage Longwalls § 75.813 High-voltage...

Switching and Rectification in Carbon-Nanotube Junctions

NASA Technical Reports Server (NTRS)

Srivastava, Deepak; Andriotis, Antonis N.; Menon, Madhu; Chernozatonskii, Leonid

2003-01-01

Multi-terminal carbon-nanotube junctions are under investigation as candidate components of nanoscale electronic devices and circuits. Three-terminal "Y" junctions of carbon nanotubes (see Figure 1) have proven to be especially interesting because (1) it is now possible to synthesize them in high yield in a controlled manner and (2) results of preliminary experimental and theoretical studies suggest that such junctions could exhibit switching and rectification properties. Following the preliminary studies, current-versus-voltage characteristics of a number of different "Y" junctions of single-wall carbon nanotubes connected to metal wires were computed. Both semiconducting and metallic nanotubes of various chiralities were considered. Most of the junctions considered were symmetric. These computations involved modeling of the quantum electrical conductivity of the carbon nanotubes and junctions, taking account of such complicating factors as the topological defects (pentagons, heptagons, and octagons) present in the hexagonal molecular structures at the junctions, and the effects of the nanotube/wire interfaces. A major component of the computational approach was the use of an efficient Green s function embedding scheme. The results of these computations showed that symmetric junctions could be expected to support both rectification and switching. The results also showed that rectification and switching properties of a junction could be expected to depend strongly on its symmetry and, to a lesser degree, on the chirality of the nanotubes. In particular, it was found that a zigzag nanotube branching at a symmetric "Y" junction could exhibit either perfect rectification or partial rectification (asymmetric current-versus-voltage characteristic, as in the example of Figure 2). It was also found that an asymmetric "Y" junction would not exhibit rectification.

Effects of Prolonged Spaceflight on Atrial Size, Atrial Electrophysiology, and Risk of Atrial Fibrillation.

PubMed

Khine, Htet W; Steding-Ehrenborg, Katarina; Hastings, Jeffrey L; Kowal, Jamie; Daniels, James D; Page, Richard L; Goldberger, Jeffery J; Ng, Jason; Adams-Huet, Beverley; Bungo, Michael W; Levine, Benjamin D

2018-05-01

The prevalence of atrial fibrillation (AF) in active astronauts is ≈5%, similar to the general population but at a younger age. Risk factors for AF include left atrial enlargement, increased number of premature atrial complexes, and certain parameters on signal-averaged electrocardiography, such as P-wave duration, root mean square voltage for the terminal 20 ms of the signal-averaged P wave, and P-wave amplitude. We aimed to evaluate changes in atrial structure, supraventricular beats, and atrial electrophysiology to determine whether spaceflight could increase the risk of AF. Thirteen astronauts underwent cardiac magnetic resonance imaging to assess atrial structure and function before and after 6 months in space and high-resolution Holter monitoring for multiple 48-hour time periods before flight, during flight, and on landing day. Left atrial volume transiently increased after 6 months in space (12±18 mL; P =0.03) without changing atrial function. Right atrial size remained unchanged. No changes in supraventricular beats were noted. One astronaut had a large increase in supraventricular ectopic beats but none developed AF. Filtered P-wave duration did not change over time, but root mean square voltage for the terminal 20 ms decreased on all fight days except landing day. No changes in P-wave amplitude were seen in leads II or V 1 except landing day for lead V 1 . Six months of spaceflight may be sufficient to cause transient changes in left atrial structure and atrial electrophysiology that increase the risk of AF. However, there was no definite evidence of increased supraventricular arrhythmias and no identified episodes of AF. © 2018 American Heart Association, Inc.

A simple process based on NH2- and CH3-terminated monolayers for low contact resistance and adherent Au electrode in bottom-contact OTFTs

NASA Astrophysics Data System (ADS)

Abdur, Rahim; Lim, Jeongeun; Jeong, Kyunghoon; Rahman, Mohammad Arifur; Kim, Jiyoung; Lee, Jaegab

2016-03-01

An efficient process for the low contact resistance and adherent source/drain Au electrode in bottom-contact organic thin film transistors (OTFTs) was developed. This was achieved by using two different surface-functional groups of self-assembled monolayers, 3-aminopropyltriethoxysilane (APS), and octadecyltrichlorosilane (OTS), combined with atmospheric-pressure (AP) plasma treatment. Prior to the deposition of Au electrode, the aminoterminated monolayer self-assembles on SiO2 dielectrics, enhancing the adhesion of Au electrode as a result of the acid-base interaction of Au with the amino-terminal groups. AP plasma treatment of the patterned Au electrode on the APS-coated surface activates the entire surface to form an OTS monolayer, allowing the formation of a high quality pentacene layer on both the electrode and active region by evaporation. In addition, negligible damage by AP plasma was observed for the device performance. The fabricated OTFTs based on the two monolayers by AP plasma treatment showed the mobility of 0.23 cm2/Vs, contact resistance of 29 kΩ-cm, threshold voltage of -1.63 V, and on/off ratio of 9.8 × 105, demonstrating the application of the simple process for robust and high-performance OTFTs. [Figure not available: see fulltext.

Multi-hundred kilowatt roll ring assembly

NASA Technical Reports Server (NTRS)

Jacobson, Peter E.

1985-01-01

A program was completed to develop an evaluation unit of a high power rotary transfer device for potential application in a space environment. This device was configured around a Roll Ring concept which performs the same function as a slip ring/brush assembly with a rolling instead of sliding interface. An eight circuit Evaluation Unit (EU) and a portable Test Fixture (TF) were designed and fabricated. The EU was designed to transfer currents to 200 amperes at a potential of as high as 500 volts for an ultimate 100 kW/circuit transfer capability. The EU was evaluated in vacuum at dc transfer currents of 50 to 200 amperes at voltages to 10 volts and at 500 volts at 2 amperes. Power transfer to levels of 2 kW through each of the eight circuits was completed. Power transfer in vacuum at levels and efficiencies not previously achieved was demonstrated. The terminal-to-terminal resistance was measured to be greater than 0.42 milliohms which translates to an efficiency at 100 kW of 99.98 percent. The EU and TF have been delivered to the Lewis Research Center and are being prepared tor testing at increased power levels and for life testing, which will include both dc and ac power.

30 CFR 75.807 - Installation of high-voltage transmission cables.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Installation of high-voltage transmission...-Voltage Distribution § 75.807 Installation of high-voltage transmission cables. [Statutory Provisions] All underground high-voltage transmission cables shall be installed only in regularly inspected air courses and...

Equivalent modeling of PMSG-based wind power plants considering LVRT capabilities: electromechanical transients in power systems.

PubMed

Ding, Ming; Zhu, Qianlong

2016-01-01

Hardware protection and control action are two kinds of low voltage ride-through technical proposals widely used in a permanent magnet synchronous generator (PMSG). This paper proposes an innovative clustering concept for the equivalent modeling of a PMSG-based wind power plant (WPP), in which the impacts of both the chopper protection and the coordinated control of active and reactive powers are taken into account. First, the post-fault DC link voltage is selected as a concentrated expression of unit parameters, incoming wind and electrical distance to a fault point to reflect the transient characteristics of PMSGs. Next, we provide an effective method for calculating the post-fault DC link voltage based on the pre-fault wind energy and the terminal voltage dip. Third, PMSGs are divided into groups by analyzing the calculated DC link voltages without any clustering algorithm. Finally, PMSGs of the same group are equivalent as one rescaled PMSG to realize the transient equivalent modeling of the PMSG-based WPP. Using the DIgSILENT PowerFactory simulation platform, the efficiency and accuracy of the proposed equivalent model are tested against the traditional equivalent WPP and the detailed WPP. The simulation results show the proposed equivalent model can be used to analyze the offline electromechanical transients in power systems.

Rapid time course of action potentials in spines and remote dendrites of mouse visual cortex neurons.

PubMed

Holthoff, Knut; Zecevic, Dejan; Konnerth, Arthur

2010-04-01

Axonally initiated action potentials back-propagate into spiny dendrites of central mammalian neurons and thereby regulate plasticity at excitatory synapses on individual spines as well as linear and supralinear integration of synaptic inputs along dendritic branches. Thus, the electrical behaviour of individual dendritic spines and terminal dendritic branches is critical for the integrative function of nerve cells. The actual dynamics of action potentials in spines and terminal branches, however, are not entirely clear, mostly because electrode recording from such small structures is not feasible. Additionally, the available membrane potential imaging techniques are limited in their sensitivity and require substantial signal averaging for the detection of electrical events at the spatial scale of individual spines. We made a critical improvement in the voltage-sensitive dye imaging technique to achieve multisite recordings of backpropagating action potentials from individual dendritic spines at a high frame rate. With this approach, we obtained direct evidence that in layer 5 pyramidal neurons from the visual cortex of juvenile mice, the rapid time course of somatic action potentials is preserved throughout all cellular compartments, including dendritic spines and terminal branches of basal and apical dendrites. The rapid time course of the action potential in spines may be a critical determinant for the precise regulation of spike timing-dependent synaptic plasticity within a narrow time window.

30 CFR 75.800 - High-voltage circuits; circuit breakers.

Code of Federal Regulations, 2010 CFR

2010-07-01

... shall be equipped with devices to provide protection against under-voltage grounded phase, short circuit... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage circuits; circuit breakers. 75.800... § 75.800 High-voltage circuits; circuit breakers. [Statutory Provisions] High-voltage circuits entering...

30 CFR 75.802 - Protection of high-voltage circuits extending underground.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Protection of high-voltage circuits extending...-Voltage Distribution § 75.802 Protection of high-voltage circuits extending underground. (a) Except as provided in paragraph (b) of this section, high-voltage circuits extending underground and supplying...

30 CFR 75.802 - Protection of high-voltage circuits extending underground.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Protection of high-voltage circuits extending...-Voltage Distribution § 75.802 Protection of high-voltage circuits extending underground. (a) Except as provided in paragraph (b) of this section, high-voltage circuits extending underground and supplying...

30 CFR 75.802 - Protection of high-voltage circuits extending underground.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Protection of high-voltage circuits extending...-Voltage Distribution § 75.802 Protection of high-voltage circuits extending underground. (a) Except as provided in paragraph (b) of this section, high-voltage circuits extending underground and supplying...

7 CFR 1755.870 - RUS specification for terminating cables.

Code of Federal Regulations, 2011 CFR

2011-01-01

... microseconds wave shape. (c) The shape of the generated wave shall be determined at a reduced voltage by... by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies... references were approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR...

7 CFR 1755.870 - RUS specification for terminating cables.

Code of Federal Regulations, 2010 CFR

2010-01-01

... microseconds wave shape. (c) The shape of the generated wave shall be determined at a reduced voltage by... by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies... references were approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR...

Formula Gives Better Contact-Resistance Values

NASA Technical Reports Server (NTRS)

Lieneweg, Udo; Hannaman, David J.

1988-01-01

Lateral currents in contact strips taken into account. Four-terminal test structures added to intergrated circuits to enable measurement of interfacial resistivities of contacts between thin conducting layers. Thin-film model simplified quasi-two-dimensional potential model that accounts adequately for complicated three-dimensional, nonuniform current densitites. Effects of nonuniformity caused by lateral current flow in strips summarized in equivalent resistance Rs and voltage Vs.

Circuits Protect Against Incorrect Power Connections

NASA Technical Reports Server (NTRS)

Delombard, Richard

1992-01-01

Simple circuits prevent application of incorrectly polarized or excessive voltages. Connected temporarily or permanently at power-connecting terminals. Devised to protect electrical and electronic equipment installed in spacecraft and subjected to variety of tests in different facilities prior to installation. Basic concept of protective circuits also applied easily to many kinds of electrical and electronic equipment that must be protected against incorrect power connections.

Energy awareness for supercapacitors using Kalman filter state-of-charge tracking

NASA Astrophysics Data System (ADS)

Nadeau, Andrew; Hassanalieragh, Moeen; Sharma, Gaurav; Soyata, Tolga

2015-11-01

Among energy buffering alternatives, supercapacitors can provide unmatched efficiency and durability. Additionally, the direct relation between a supercapacitor's terminal voltage and stored energy can improve energy awareness. However, a simple capacitive approximation cannot adequately represent the stored energy in a supercapacitor. It is shown that the three branch equivalent circuit model provides more accurate energy awareness. This equivalent circuit uses three capacitances and associated resistances to represent the supercapacitor's internal SOC (state-of-charge). However, the SOC cannot be determined from one observation of the terminal voltage, and must be tracked over time using inexact measurements. We present: 1) a Kalman filtering solution for tracking the SOC; 2) an on-line system identification procedure to efficiently estimate the equivalent circuit's parameters; and 3) experimental validation of both parameter estimation and SOC tracking for 5 F, 10 F, 50 F, and 350 F supercapacitors. Validation is done within the operating range of a solar powered application and the associated power variability due to energy harvesting. The proposed techniques are benchmarked against the simple capacitive model and prior parameter estimation techniques, and provide a 67% reduction in root-mean-square error for predicting usable buffered energy.

Role of voltage-sensitive receptors in nicotinic transmission.

PubMed Central

Lester, H A; Koblin, D D; Sheridan, R E

1978-01-01

This paper compares the conductance induced by bath-applied acetyl-choline (ACh) and by the same transmitter released from nerve terminals at Electrophorus electroplaques. For the former case, dose-response relations are characterized by the maximal agonist-induced conductance, rgamma (130 mmho/cm2), and by the concentration which induces half this conductance; this concentration is termed Kapp and equals 50 micron at -85 mV. For the latter case, neurally evoked postsynaptic currents (PSCs) are characterized by the peak conductance during strongly facilitated release, gPSC, and by the rate constant for decay, alpha. Since gPSC roughly equals rgamma, it is concluded that the PSC activates nearly all available receptor channels. These and other data agree with recent estimates that during the growth phase of the quantal response, (a) the ACh concentration is at least several hundred micromolar; and (b) most nearby channels are activated. However both alpha and Kapp increase during depolarization, at a rate of about e-fold per 86 mV. These observations on voltage sensitivity suggest that a suprathreshold synaptic event is rapidly terminated because the action potential abruptly releases ACh molecules from receptors. PMID:630039

Control Strategies for the DAB Based PV Interface System

PubMed Central

El-Helw, Hadi M.; Al-Hasheem, Mohamed; Marei, Mostafa I.

2016-01-01

This paper presents an interface system based on the Dual Active Bridge (DAB) converter for Photovoltaic (PV) arrays. Two control strategies are proposed for the DAB converter to harvest the maximum power from the PV array. The first strategy is based on a simple PI controller to regulate the terminal PV voltage through the phase shift angle of the DAB converter. The Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) technique is utilized to set the reference of the PV terminal voltage. The second strategy presented in this paper employs the Artificial Neural Network (ANN) to directly set the phase shift angle of the DAB converter that results in harvesting maximum power. This feed-forward strategy overcomes the stability issues of the feedback strategy. The proposed PV interface systems are modeled and simulated using MATLAB/SIMULINK and the EMTDC/PSCAD software packages. The simulation results reveal accurate and fast response of the proposed systems. The dynamic performance of the proposed feed-forward strategy outdoes that of the feedback strategy in terms of accuracy and response time. Moreover, an experimental prototype is built to test and validate the proposed PV interface system. PMID:27560138

Reprogrammable read only variable threshold transistor memory with isolated addressing buffer

DOEpatents

Lodi, Robert J.

1976-01-01

A monolithic integrated circuit, fully decoded memory comprises a rectangular array of variable threshold field effect transistors organized into a plurality of multi-bit words. Binary address inputs to the memory are decoded by a field effect transistor decoder into a plurality of word selection lines each of which activates an address buffer circuit. Each address buffer circuit, in turn, drives a word line of the memory array. In accordance with the word line selected by the decoder the activated buffer circuit directs reading or writing voltages to the transistors comprising the memory words. All of the buffer circuits additionally are connected to a common terminal for clearing all of the memory transistors to a predetermined state by the application to the common terminal of a large magnitude voltage of a predetermined polarity. The address decoder, the buffer and the memory array, as well as control and input/output control and buffer field effect transistor circuits, are fabricated on a common substrate with means provided to isolate the substrate of the address buffer transistors from the remainder of the substrate so that the bulk clearing function of simultaneously placing all of the memory transistors into a predetermined state can be performed.

Perovskite-perovskite tandem photovoltaics with optimized band gaps

NASA Astrophysics Data System (ADS)

Eperon, Giles E.; Leijtens, Tomas; Bush, Kevin A.; Prasanna, Rohit; Green, Thomas; Wang, Jacob Tse-Wei; McMeekin, David P.; Volonakis, George; Milot, Rebecca L.; May, Richard; Palmstrom, Axel; Slotcavage, Daniel J.; Belisle, Rebecca A.; Patel, Jay B.; Parrott, Elizabeth S.; Sutton, Rebecca J.; Ma, Wen; Moghadam, Farhad; Conings, Bert; Babayigit, Aslihan; Boyen, Hans-Gerd; Bent, Stacey; Giustino, Feliciano; Herz, Laura M.; Johnston, Michael B.; McGehee, Michael D.; Snaith, Henry J.

2016-11-01

We demonstrate four- and two-terminal perovskite-perovskite tandem solar cells with ideally matched band gaps. We develop an infrared-absorbing 1.2-electron volt band-gap perovskite, FA0.75Cs0.25Sn0.5Pb0.5I3, that can deliver 14.8% efficiency. By combining this material with a wider-band gap FA0.83Cs0.17Pb(I0.5Br0.5)3 material, we achieve monolithic two-terminal tandem efficiencies of 17.0% with >1.65-volt open-circuit voltage. We also make mechanically stacked four-terminal tandem cells and obtain 20.3% efficiency. Notably, we find that our infrared-absorbing perovskite cells exhibit excellent thermal and atmospheric stability, not previously achieved for Sn-based perovskites. This device architecture and materials set will enable “all-perovskite” thin-film solar cells to reach the highest efficiencies in the long term at the lowest costs.

Evidence that protons act as neurotransmitters at vestibular hair cell-calyx afferent synapses.

PubMed

Highstein, Stephen M; Holstein, Gay R; Mann, Mary Anne; Rabbitt, Richard D

2014-04-08

Present data support the conclusion that protons serve as an important neurotransmitter to convey excitatory stimuli from inner ear type I vestibular hair cells to postsynaptic calyx nerve terminals. Time-resolved pH imaging revealed stimulus-evoked extrusion of protons from hair cells and a subsequent buildup of [H(+)] within the confined chalice-shaped synaptic cleft (ΔpH ∼ -0.2). Whole-cell voltage-clamp recordings revealed a concomitant nonquantal excitatory postsynaptic current in the calyx terminal that was causally modulated by cleft acidification. The time course of [H(+)] buildup limits the speed of this intercellular signaling mechanism, but for tonic signals such as gravity, protonergic transmission offers a significant metabolic advantage over quantal excitatory postsynaptic currents--an advantage that may have driven the proliferation of postsynaptic calyx terminals in the inner ear vestibular organs of contemporary amniotes.

Post-Test Inspection of NASA's Evolutionary Xenon Thruster Long-Duration Test Hardware: Discharge and Neutralizer Cathodes

NASA Technical Reports Server (NTRS)

Shastry, Rohit; Soulas, George C.

2016-01-01

The NEXT Long-Duration Test is part of a comprehensive thruster service life assessment intended to demonstrate overall throughput capability, validate service life models, quantify wear rates as a function of time and operating condition, and identify any unknown life-limiting mechanisms. The test was voluntarily terminated in April 2014 after demonstrating 51,184 hours of high-voltage operation, 918 kg of propellant throughput, and 35.5 MN-s of total impulse. The post-test inspection of the thruster hardware began shortly afterwards with a combination of non-destructive and destructive analysis techniques, and is presently nearing completion. This presentation presents relevant results of the post-test inspection for both discharge and neutralizer cathodes.

Evaluation program for secondary spacecraft cells: Initial evaluation tests of General Electric Company, 6.0 ampere-hour nickel-cadmium spacecraft cells for the GOES-D, E and F satellite program

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1979-01-01

The tests are to insure that all cells put into the life cycle program are of high quality by the screening of cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open-circuit voltage above 1.150 volts during the internal short test. Test limits specify those values at which a cell is to be terminated from charge or discharge. Requirements are referenced to normally expected values based on past performance of aerospace nickel-cadmium cells with demonstrated life characteristics. Recommendations for the improvement of the manufacturing processes are presented.

Initial evaluation tests of General Electric Company 26.5 ampere-hour nickel-cadmium spacecraft cells with auxiliary electrodes for the TIROS-N and NOAA-A satellites

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1978-01-01

This evaluation test program had the purpose to insure that all cells put into the life cycle program are of high quality by the screening of cells found to have electrolyte leakage, internal shorts, low capacity, or inability of any cell to recover its open-circuit voltage above 1.150 volts during the internal short test. Test limits specify those values at which a cell is to be terminated from charge or discharge. Requirements are referenced to as normally expected values based on past performance of aerospace nickel-cadmium cells with demonstrated life characteristics. A requirement does not constitute a limit for discontinuance from test.

Retinoschisin, a New Binding Partner for L-type Voltage-gated Calcium Channels in the Retina*

PubMed Central

Shi, Liheng; Jian, Kuihuan; Ko, Michael L.; Trump, Dorothy; Ko, Gladys Y.-P.

2009-01-01

The L-type voltage-gated calcium channels (L-VGCCs) are activated under high depolarization voltages. They are vital for diverse biological events, including cell excitability, differentiation, and synaptic transmission. In retinal photoreceptors, L-VGCCs are responsible for neurotransmitter release and are under circadian influences. However, the mechanism of L-VGCC regulation in photoreceptors is not fully understood. Here, we show that retinoschisin, a highly conserved extracellular protein, interacts with the L-VGCCα1D subunit and regulates its activities in a circadian manner. Mutations in the gene encoding retinoschisin (RS1) cause retinal disorganization that leads to early onset of macular degeneration. Since ion channel activities can be modulated through interactions with extracellular proteins, disruption of these interactions can alter physiology and be the root cause of disease states. Co-immunoprecipitation and mammalian two-hybrid assays showed that retinoschisin and the N-terminal fragment of the L-VGCCα1 subunit physically interacted with one another. The expression and secretion of retinoschisin are under circadian regulation with a peak at night and nadir during the day. Inhibition of L-type VGCCs decreased membrane-bound retinoschisin at night. Overexpression of a missense RS1 mutant gene, R141G, into chicken cone photoreceptors caused a decrease of L-type VGCC currents at night. Our findings demonstrate a novel bidirectional relationship between an ion channel and an extracellular protein; L-type VGCCs regulate the circadian rhythm of retinoschisin secretion, whereas secreted retinoschisin feeds back to regulate L-type VGCCs. Therefore, physical interactions between L-VGCCα1 subunits and retinoschisin play an important role in the membrane retention of L-VGCCα1 subunits and photoreceptor-bipolar synaptic transmission. PMID:19074145

Identification, by RT-PCR, of eight novel I₂-conotoxins from the worm-hunting cone snails Conus brunneus, Conus nux, and Conus princeps from the eastern Pacific (Mexico).

PubMed

Zamora-Bustillos, R; Rivera-Reyes, R; Aguilar, M B; Michel-Morfín, E; Landa-Jaime, V; Falcón, A; Heimer, E P

2014-03-01

Marine snails of the genus Conus (∼500 species) are tropical predators that produce venoms for capturing prey, defense and competitive interactions. These venoms contain 50-200 different peptides ("conotoxins") that generally comprise 7-40 amino acid residues (including 0-5 disulfide bridges), and that frequently contain diverse posttranslational modifications, some of which have been demonstrated to be important for folding, stability, and biological activity. Most conotoxins affect voltage- and ligand-gated ion channels, G protein-coupled receptors, and neurotransmitter transporters, generally with high affinity and specificity. Due to these features, several conotoxins are used as molecular tools, diagnostic agents, medicines, and models for drug design. Based on the signal sequence of their precursors, conotoxins have been classified into genetic superfamilies, whereas their molecular targets allow them to be classified into pharmacological families. The objective of this work was to identify and analyze partial cDNAs encoding precursors of conotoxins belonging to I superfamily from three vermivorous species of the Mexican Pacific coast: C. brunneus, C. nux and C. princeps. The precursors identified contain diverse numbers of amino acid residues (C. brunneus, 65 or 71; C. nux, 70; C. princeps, 72 or 73), and all include a highly conserved signal peptide, a C-terminal propeptide, and a mature toxin. All the latter have one of the typical Cys frameworks of the I-conotoxins (C-C-CC-CC-C-C). The prepropeptides belong to the I2-superfamily, and encode eight different hydrophilic and acidic mature toxins, rather similar among them, and some of which have similarity with I2-conotoxins targeting voltage- and voltage-and-calcium-gated potassium channels. Copyright © 2014 Elsevier Inc. All rights reserved.

Calibration of Voltage Transformers and High- Voltage Capacitors at NIST

PubMed Central

Anderson, William E.

1989-01-01

The National Institute of Standards and Technology (NIST) calibration service for voltage transformers and high-voltage capacitors is described. The service for voltage transformers provides measurements of ratio correction factors and phase angles at primary voltages up to 170 kV and secondary voltages as low as 10 V at 60 Hz. Calibrations at frequencies from 50–400 Hz are available over a more limited voltage range. The service for high-voltage capacitors provides measurements of capacitance and dissipation factor at applied voltages ranging from 100 V to 170 kV at 60 Hz depending on the nominal capacitance. Calibrations over a reduced voltage range at other frequencies are also available. As in the case with voltage transformers, these voltage constraints are determined by the facilities at NIST. PMID:28053409

A new mechanism of voltage-dependent gating exposed by KV10.1 channels interrupted between voltage sensor and pore.

PubMed

Tomczak, Adam P; Fernández-Trillo, Jorge; Bharill, Shashank; Papp, Ferenc; Panyi, Gyorgy; Stühmer, Walter; Isacoff, Ehud Y; Pardo, Luis A

2017-05-01

Voltage-gated ion channels couple transmembrane potential changes to ion flow. Conformational changes in the voltage-sensing domain (VSD) of the channel are thought to be transmitted to the pore domain (PD) through an α-helical linker between them (S4-S5 linker). However, our recent work on channels disrupted in the S4-S5 linker has challenged this interpretation for the KCNH family. Furthermore, a recent single-particle cryo-electron microscopy structure of K V 10.1 revealed that the S4-S5 linker is a short loop in this KCNH family member, confirming the need for an alternative gating model. Here we use "split" channels made by expression of VSD and PD as separate fragments to investigate the mechanism of gating in K V 10.1. We find that disruption of the covalent connection within the S4 helix compromises the ability of channels to close at negative voltage, whereas disconnecting the S4-S5 linker from S5 slows down activation and deactivation kinetics. Surprisingly, voltage-clamp fluorometry and MTS accessibility assays show that the motion of the S4 voltage sensor is virtually unaffected when VSD and PD are not covalently bound. Finally, experiments using constitutively open PD mutants suggest that the presence of the VSD is structurally important for the conducting conformation of the pore. Collectively, our observations offer partial support to the gating model that assumes that an inward motion of the C-terminal S4 helix, rather than the S4-S5 linker, closes the channel gate, while also suggesting that control of the pore by the voltage sensor involves more than one mechanism. © 2017 Tomczak et al.