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1

Steady-State Analysis of the Series Resistance-Inductance Circuit Controlled by Silicon Controlled Rectifiers  

Microsoft Academic Search

The series resistance-inductance circuit controlled by triggering of a silicon-controlled rectifier pair results in load voltage and current of different nonsinusoidal waveforms. Rigorous analysis of the harmonic voltages and currents results in calculated values agreeing very closely with measurements. The effective power factor is found to remain almost constant at the sinusoidal value. Fundamental load power can be accurately measured

William Shepherd

1965-01-01

2

A series-resonant silicon-controlled-rectifier power processor for ion thrusters  

NASA Technical Reports Server (NTRS)

A program to develop a power processing system for ion thrusters is presented. Basic operation of the silicon controlled rectifier series inverter circuitry is examined. The approach for synthesizing such circuits into a system which limits the electrical stress levels on the power source, semiconductor switching elements, and the ion thruster load is described. Experimental results are presented for a 2.5-kW breadboard system designed to operate a 20-cm ion thruster.

Shumaker, H. A.; Biess, J. J.; Goldin, D. S.

1973-01-01

3

Multiple-finger turn-on uniformity in silicon-controlled rectifiers  

NASA Astrophysics Data System (ADS)

Turn-on uniformity of two multi-finger silicon-controlled rectifiers (SCRs) with different combinations of anode/cathode regions are studied using the transmission line pulsing (TLP) tester. The finger turn-on mechanisms of these devices are explained from the current flow path and equivalent circuit views. The dV/ dt effect of pulses with different rise times on the finger turn-on behavior of the SCRs are also investigated experimentally.

Li, You; Liou, Juin J.

2010-12-01

4

Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles  

NASA Technical Reports Server (NTRS)

The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

Gourash, F.

1984-01-01

5

Reliable Breakdown Obtained in Silicon Carbide Rectifiers  

NASA Technical Reports Server (NTRS)

The High Temperature Integrated Electronics and Sensor (HTIES) Program at the NASA Lewis Research Center is currently developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. Silicon carbide's demonstrated ability to function under extreme high-temperature, high-power, and/or high-radiation conditions will enable significant improvements to a far-ranging variety of applications and systems. These range from improved high-voltage switching for energy savings in public electric power distribution and electric vehicles, to more powerful microwave electronics for radar and cellular communications, to sensor and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines.

Neudeck, Philip G.

1997-01-01

6

Silicon Carbide High-Temperature Power Rectifiers Fabricated and Characterized  

NASA Technical Reports Server (NTRS)

The High Temperature Integrated Electronics and Sensors (HTIES) team at the NASA Lewis Research Center is developing silicon carbide (SiC) for use in harsh conditions where silicon, the semiconductor used in nearly all of today's electronics, cannot function. Silicon carbide's demonstrated ability to function under extreme high-temperature, high power, and/or high-radiation conditions will enable significant improvements to a far ranging variety of applications and systems. These improvements range from improved high-voltage switching for energy savings in public electric power distribution and electric vehicles, to more powerful microwave electronics for radar and cellular communications, to sensors and controls for cleaner-burning, more fuel-efficient jet aircraft and automobile engines. In the case of jet engines, uncooled operation of 300 to 600 C SiC power actuator electronics mounted in key high-temperature areas would greatly enhance system performance and reliability. Because silicon cannot function at these elevated temperatures, the semiconductor device circuit components must be made of SiC. Lewis' HTIES group recently fabricated and characterized high-temperature SiC rectifier diodes whose record-breaking characteristics represent significant progress toward the realization of advanced high-temperature actuator control circuits. The first figure illustrates the 600 C probe-testing of a Lewis SiC pn-junction rectifier diode sitting on top of a glowing red-hot heating element. The second figure shows the current-versus voltage rectifying characteristics recorded at 600 C. At this high temperature, the diodes were able to "turn-on" to conduct 4 A of current when forward biased, and yet block the flow of current ($quot;turn-off") when reverse biases as high as 150 V were applied. This device represents a new record for semiconductor device operation, in that no previous semiconductor electronic device has ever simultaneously demonstrated 600 C functionality, and 4-A turn-on and 150-V rectification. The high operating current was achieved despite severe device size limitations imposed by present-day SiC wafer defect densities. Further substantial increases in device performance can be expected when SiC wafer defect densities decrease as SiC wafer production technology matures.

1996-01-01

7

A fuzzy-logic-based controller for active rectifier  

Microsoft Academic Search

This paper presents a current-sensorless active rectifier specifically designed for low-cost applications. Both the control and the modulation use fuzzy logic. A simple model of the system is given in order to explain the current feedforward control using fuzzy logic and the fuzzy-logic-based modulation, then, the new algorithm is analyzed looking for high performance even using small passive elements and

Carlo Cecati; Antonio Dell' Aquila; Marco Liserre; Antonio Ometto

2003-01-01

8

THREE-PHASE CONTROLLED RECTIFIERS Author : Juan Dixon (Ph.D.)  

E-print Network

commutation overlap, each valve conducts during 120° per period. The secondary currents (thyristor currents categories: Line Commutated Controlled Rectifiers (Thyristor Rectifiers), and Force Commutated PWM Rectifiers uses three, common-cathode thyristor arrangement. In this figure, the power supply, and the transformer

Catholic University of Chile (Universidad Católica de Chile)

9

Comparison of Ti and Pt silicon carbide Schottky rectifiers  

Microsoft Academic Search

This paper describes the fabrication and characterization of high breakdown voltage titanium and platinum Schottky contacts to silicon carbide for high temperature and high frequency applications. Diodes fabricated with both Pt and Ti showed excellent on-state conduction characteristics with forward voltage drop of ~1.1 V at 100 A\\/cm2 for a temperature range of 25C to 200C. The reverse I-V characteristics

M. Bhatnagar; H. Nakanishi; P. K. Mclarty; B. J. Baliga; B. Patnaik; N. Parikh

1992-01-01

10

Modelling a single phase voltage controlled rectifier using Laplace transforms  

NASA Technical Reports Server (NTRS)

The development of a 20 kHz, AC power system by NASA for large space projects has spurred a need to develop models for the equipment which will be used on these single phase systems. To date, models for the AC source (i.e., inverters) have been developed. It is the intent of this paper to develop a method to model the single phase voltage controlled rectifiers which will be attached to the AC power grid as an interface for connected loads. A modified version of EPRI's HARMFLO program is used as the shell for these models. The results obtained from the model developed in this paper are quite adequate for the analysis of problems such as voltage resonance. The unique technique presented in this paper uses the Laplace transforms to determine the harmonic content of the load current of the rectifier rather than a curve fitting technique. Laplace transforms yield the coefficient of the differential equations which model the line current to the rectifier directly.

Kraft, L. Alan; Kankam, M. David

1992-01-01

11

High temperature rectifiers and MOS devices in 6H-silicon carbide  

NASA Astrophysics Data System (ADS)

A major emphasis in the aerospace industry has been to increase the performance and efficiency of aircraft engines (including helicopters). Most of the improvements require the engine to run hotter, be more compact and more precisely controlled. All of these requirements increase the temperature of an increasing number of electronic components on the engine. This contract involved the development of two types of solid state devices for use in various engine applications using silicon carbide which is the premiere semiconductor material for high temperature (and other) applications. One device is a high voltage, low current rectifier which can operate to at least 350 deg C for use in an igniter circuit. The developments required involved decreasing the doping level of the background layer in epitaxial growth, improving the passivation and packaging to withstand the high voltage and high temperature. The other is a 350 deg C small signal MOSFET which can be used as an amplifier for a variety of sensors. For this portion of the research, the major focus was on characterization of the thermal oxide and the oxide interface through fabrication and characterization of MOS capacitors and various MOSFET designs.

Palmour, J. W.; Edmond, J. A.; Carter, C. H., Jr.

1992-04-01

12

Techniques for minimizing the input current distortion of current-controlled single-phase boost rectifiers  

Microsoft Academic Search

Techniques for minimizing the input current distortion of current-controlled single-phase boost rectifiers are described. The switching patterns of several boost rectifiers are examined to identify the nature of their input current waveforms. This analysis is used to examine the low-frequency current distortion levels, and hence the power quality, associated with the rectifiers. A PWM (pulse width modulation) strategy that selectively

John C. Salmon

1993-01-01

13

Discrete-time Model Following Control of Inverter with Rectifier Load  

NASA Astrophysics Data System (ADS)

Electronic apparatus, such as a computer, are a capacitor input type rectifier load for a power supply. The rectifier load causes the fact that a power source voltage waveform is distorted. This paper describes the output voltage characteristic of the single phase PWM inverter applied a discrete-time model following control to the rectifier load. First the rectifier load model of a discrete time system is considered. Next, the discrete- time model following control system used for this load is described. Then, a simulation result and an experimental result are examined. The simulation results is shown that this method has robustness to the load change. The experimental system consists of an inverter controlled by a digital signal processor (DSP) and the rectifier load. The validity of a simulation result is shown by the experiment.

Umemura, Atsushi; Haneyoshi, Toshimasa; Saito, Yukio; Harashima, Fumio

14

Two passivity-based approaches to the control of the H-bridge-based multilevel rectifier  

Microsoft Academic Search

This paper deals with a multilevel H-bridge based front-end rectifier to be used in high voltage high power applications. The main control issue for such type of converter is stabilization. In fact, voltage unbalancing across the distinct DC links can lead to system instability. In this paper two passivity-based control (PBC) algorithms for the H-bridge-based multilevel rectifier are analysed and

Antonio Dell' Aquila; Marco Liserre; Vito G. Monopoli; Paola Rotondo

2003-01-01

15

Smart vector-decoupling control of three phase rectifiers for grid connectivity of sustainable energy sources  

Microsoft Academic Search

In this paper, some of the aspects related to the connectivity of DC microgrids to the main grid are investigated. The system under study is dependent mainly on sustainable energy sources. A fully controlled rectifier has been designed to tie the DC grid with the AC one. A vector decoupling controlled sinusoidal pulse width modulation (SPWM) technique has been used

Ahmed Mohamed; Osama A. Mohammed

2011-01-01

16

Analysis, Design and Control of 1MW, High Power Factor and High Current Rectifier System  

E-print Network

Analysis, Design and Control of 1MW, High Power Factor and High Current Rectifier System Jitendra of DSTATCOM. Design and control of system are carried out such that input power factor remains greater than 0 are the two most widely used topologies. These topologies are used in industry up-to power ratings of hundreds

Paderborn, Universität

17

A critical review of ohmic and rectifying contacts for silicon carbide  

Microsoft Academic Search

For more than three decades, SiC has been investigated as a wide band gap semiconductor. This paper reviews ohmic and rectifying metal contacts on n- and p-type ?- and ?-SiC reported throughout that time period. Electrical characteristics, Schottky barrier heights (SBHs), thermal stability, and chemical reactions are discussed. Most metals formed very good rectifying contacts in the as-deposited condition on

Lisa M. Porter; Robert F. Davis

1995-01-01

18

A high efficiency MHD lamp ballast with a frequency controlled synchronous rectifier  

Microsoft Academic Search

In this paper, in order to develop a simple and high efficient ballast without an external ignitor, a half-bridge type ballast with a coupled inductor and a frequency controlled synchronous rectifier is proposed. The internal LC resonance of the buck converter is used to generate a high voltage pulse for the ignition, and the coupled inductor filter is used for

I. K. Lee; B. H. Cho

2004-01-01

19

Input Power Measurement Techniques for Single-Phase Digitally Controlled PFC Rectifiers  

E-print Network

Input Power Measurement Techniques for Single-Phase Digitally Controlled PFC Rectifiers Barry A. Mather and Dragan Maksimovi6 Colorado Power Electronics Center University of Colorado, Boulder, CO Email: {matherb, maksimov} @colorado.edu Abstract- Accurate input power measurements for off-line power supplies

20

Passivity-based control of a single-phase H-bridge multilevel active rectifier  

Microsoft Academic Search

This paper proposes a passivity-based controller for a H-bridge multilevel rectifier feeding a number of DC buses. The balance of the DC voltages under different operating conditions and a satisfactory dynamic behaviour at load step changes are guaranteed through the independent control of each H-bridge multilevel switching function. Thus a new modulation strategy is proposed to obtain a multilevel voltage

A. Dell'Aquila; M. Liserre; V. G. Monopoli; C. Cecati

2002-01-01

21

An energy-based control for an n-H-bridges multilevel active rectifier  

Microsoft Academic Search

This paper deals with the control of a multilevel n-H-bridges front-end rectifier. This topology allows n distinct dc buses to be fed by the same ac source offering a high loading flexibility suitable for traction applications as well as for industrial automation plants. However, this flexibility can lead the system to instability if the dc buses operate at different voltage

A. Dell'Aquila; M. Liserre; V. G. Monopoli; P. Rotondo

2005-01-01

22

Nanoscale spin rectifiers controlled by the Stark effect  

NASA Astrophysics Data System (ADS)

The control of orbitals and spin states of single electrons is a key ingredient for quantum information processing and novel detection schemes and is, more generally, of great relevance for spintronics. Coulomb and spin blockade in double quantum dots enable advanced single-spin operations that would be available even for room-temperature applications with sufficiently small devices. To date, however, spin operations in double quantum dots have typically been observed at sub-kelvin temperatures, a key reason being that it is very challenging to scale a double quantum dot system while retaining independent field-effect control of individual dots. Here, we show that the quantum-confined Stark effect allows two dots only 5?nm apart to be independently addressed without the requirement for aligned nanometre-sized local gating. We thus demonstrate a scalable method to fully control a double quantum dot device, regardless of its physical size. In the present implementation we present InAs/InP nanowire double quantum dots that display an experimentally detectable spin blockade up to 10?K. We also report and discuss an unexpected re-entrant spin blockade lifting as a function of the magnetic field intensity.

Rossella, Francesco; Bertoni, Andrea; Ercolani, Daniele; Rontani, Massimo; Sorba, Lucia; Beltram, Fabio; Roddaro, Stefano

2014-12-01

23

Nanoscale spin rectifiers controlled by the Stark effect.  

PubMed

The control of orbitals and spin states of single electrons is a key ingredient for quantum information processing and novel detection schemes and is, more generally, of great relevance for spintronics. Coulomb and spin blockade in double quantum dots enable advanced single-spin operations that would be available even for room-temperature applications with sufficiently small devices. To date, however, spin operations in double quantum dots have typically been observed at sub-kelvin temperatures, a key reason being that it is very challenging to scale a double quantum dot system while retaining independent field-effect control of individual dots. Here, we show that the quantum-confined Stark effect allows two dots only 5?nm apart to be independently addressed without the requirement for aligned nanometre-sized local gating. We thus demonstrate a scalable method to fully control a double quantum dot device, regardless of its physical size. In the present implementation we present InAs/InP nanowire double quantum dots that display an experimentally detectable spin blockade up to 10?K. We also report and discuss an unexpected re-entrant spin blockade lifting as a function of the magnetic field intensity. PMID:25383514

Rossella, Francesco; Bertoni, Andrea; Ercolani, Daniele; Rontani, Massimo; Sorba, Lucia; Beltram, Fabio; Roddaro, Stefano

2014-12-01

24

WASTE MINIMIZATION ASSESSMENT FOR A MANUFACTURER OF SILICON-CONTROLLED RECTIFIERS AND SCHOTTKY RECTIFIERS  

EPA Science Inventory

The U.S. Environmental Protection Agency (EPA) has funded a pilot project to assist small- and medium-size manufacturers who want to minimize their generation of waste but who lack the expertise to do so. In an effort to assist these manufacturers Waste Minimization Assessment Ce...

25

An Integrated Power-Efficient Active Rectifier With Offset-Controlled High Speed Comparators for Inductively Powered Applications  

PubMed Central

We present an active full-wave rectifier with offset-controlled high speed comparators in standard CMOS that provides high power conversion efficiency (PCE) in high frequency (HF) range for inductively powered devices. This rectifier provides much lower dropout voltage and far better PCE compared to the passive on-chip or off-chip rectifiers. The built-in offset-control functions in the comparators compensate for both turn-on and turn-off delays in the main rectifying switches, thus maximizing the forward current delivered to the load and minimizing the back current to improve the PCE. We have fabricated this active rectifier in a 0.5-?m 3M2P standard CMOS process, occupying 0.18 mm2 of chip area. With 3.8 V peak ac input at 13.56 MHz, the rectifier provides 3.12 V dc output to a 500 ? load, resulting in the PCE of 80.2%, which is the highest measured at this frequency. In addition, overvoltage protection (OVP) as safety measure and built-in back telemetry capabilities have been incorporated in our design using detuning and load shift keying (LSK) techniques, respectively, and tested. PMID:22174666

Lee, Hyung-Min; Ghovanloo, Maysam

2011-01-01

26

Design and evaluation of a cellular rectifier system with distributed control  

E-print Network

This paper presents the design and experimental evaluation of a six-cell 6 kW cellular (parallel) rectifier system which operates at nearly unity power factor. The cellular rectifier system implements both distributed load ...

Perreault, David J.

27

Nanoscale Spin Seebeck Rectifier: Controlling Thermal Spin Transport across Insulating Magnetic Junctions with Localized Spin  

E-print Network

The spin Seebeck effect is studied across a charge insulating magnetic junction, in which thermal-spin conjugate transport is assisted by the exchange interactions between the localized spin in the center and electrons in metallic leads. We show that, in contrast with bulk spin Seebeck effect, the figure of merit of such nanoscale thermal-spin conversion can be infinite, leading to the ideal Carnot efficiency in the linear response regime. We also find that in the nonlinear spin Seebeck transport regime, the device possesses the asymmetric and negative differential spin Seebeck effects. In the last, the situations with leaking electron tunneling are also discussed. This nanoscale thermal spin rectifier, by tuning the junction parameters, can act as a spin Seebeck diode, spin Seebeck transistor and spin Seebeck switch, which could have substantial implications for flexible thermal and information control in molecular spin caloritronics.

Jie Ren; Jonas Fransson; Jian-Xin Zhu

2014-06-20

28

A fuzzy-controlled active front-end rectifier with current harmonic filtering characteristics and minimum sensing variables  

Microsoft Academic Search

A control strategy which allows conventional voltage-source current-controlled (VSCC) pulsewidth modulation (PWM) rectifiers to work simultaneously as active power filters is presented. The proposed control strategy also allows compensating the system power factor and compensating unbalanced loads. The measurement and\\/or calculation of the harmonics and reactive power are not required, making the proposed control scheme very simple. The active front-end

Juan W. Dixon; Jose M. Contardo; L. A. Moran

1999-01-01

29

Auto-tuning of digitally controlled single-phase low harmonic rectifiers and inverters  

NASA Astrophysics Data System (ADS)

Effective power transfer has been one of the main issues in power electronics. In particular, low-harmonic alternating current (AC) shaping is required by various regulations at the interface between AC power grid and direct current (DC) loads or sources. In order to meet rapidly evolving efficiency standards and environmental concerns, intelligent AC current shaping strategies are required. In the power converter stage, however, inherent uncertainties caused by passive component tolerances and changes in operating conditions may impair the control loop stability, while mis-detection of operating modes over wide load range aggravates the situation further. This thesis introduces an auto-tuning technique in digitally controlled single-phase AC-DC rectifiers and DC-AC inverters. The approach is capable of precise on-line estimation of the power stage passive component values. The control loop compensator parameters are modified adaptively to maintain the nominal stability margins and control loop bandwidth based on the estimated component values. Furthermore, accurate continuous conduction mode (CCM) and discontinuous conduction mode (DCM) boundary detection is achieved as a result of the tuning process, without the need for additional circuitry. Implementation of the tuning approach is relatively simple. The proposed tuning approach is verified on experimental AC-DC and DC-AC prototypes.

Moon, Sungwoo

2011-12-01

30

Selecting New Rectifier Features  

Microsoft Academic Search

New approaches to system powering are being introduced, designed to meet the requirements of an increasingly distributed communication network. Unattended installations generally require autonomous operation. This mode of operation can be significantly enhanced by remote surveillance and control. Rectifiers designed for new power system architectures usually incroporate provisions for interaction with control microprocessors. The monitoring, measurement, and control features which

N. Tullius

1984-01-01

31

Optimum control of the rectifier with an additional series active circuit of a capacitive type system  

Microsoft Academic Search

The authors describe how the most effective way of improvement of a rectifier waveform smoother's characteristics is the introduction to their structure of active circuits. One of the perspective schemes of such type is considered in this article using an additional series active circuit of a capacitive type

B. A. Baginskiy; V. V. Ofitserov; V. A. Pomortsev

2000-01-01

32

Transformer-rectifier flux pump using inductive current transfer and thermally controlled Nb(3)Sn cryotrons.  

PubMed

Transformer-rectifier flux pumps using thermally switched Nb(3)Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz. PMID:18699368

Atherton, D L; Davies, R

1979-10-01

33

Rectifier cabinet static breaker  

DOEpatents

A rectifier cabinet static breaker replaces a blocking diode pair with an SCR and the installation of a power transistor in parallel with the latch contactor to commutate the SCR to the off state. The SCR serves as a static breaker with fast turnoff capability providing an alternative way of achieving reactor scram in addition to performing the function of the replaced blocking diodes. The control circuitry for the rectifier cabinet static breaker includes on-line test capability and an LED indicator light to denote successful test completion. Current limit circuitry provides high-speed protection in the event of overload.

Costantino, Jr, Roger A. (Mifflin, PA); Gliebe, Ronald J. (Library, PA)

1992-09-01

34

Controllable valley splitting in silicon quantum devices  

E-print Network

ARTICLES Controllable valley splitting in silicon quantum devices SRIJIT GOSWAMI1 *, K. A. SLINKER1, the multiple valleys in the silicon conduction band are potentially a serious source of decoherence for spin will be threatened. In strained-silicon quantum wells, there are two such degenerate valleys13 , whose quantum

Coppersmith, Susan N.

35

Overview of PI-Based Solutions for the Control of DC Buses of a Single-Phase H-Bridge Multilevel Active Rectifier  

Microsoft Academic Search

The H-bridge-based multilevel active rectifier is an attractive topology that allows feeding of multiple dc loads. The main control problem is to manage state variables (one current plus dc voltages) with only switching functions. In this paper, three PI-based solutions are discussed, and the tuning of the best solution is addressed in case resonant controllers are used instead of classical

Antonio Dell'Aquila; Marco Liserre; Vito Giuseppe Monopoli; Paola Rotondo

2008-01-01

36

Overview of PI-based solutions for the control of the dc-buses of a single-phase H-bridge multilevel active rectifier  

Microsoft Academic Search

The H-bridge based multilevel active rectifier is an attractive topology that allows feeding of multiple dc loads. However the balancing of the dc buses often causes instability problems. The main control problem is to manage n+1 state variables (one current plus n dc voltages) with only n switching functions. In this paper several PI-based solutions are reviewed through simulations and

Antonio Dell' Aquila; Marco Liserre; Vito G. Monopoli; Paola Rotondo

2004-01-01

37

A Fault-Tolerant Control Strategy for Cascaded H-Bridge Multilevel Rectifiers  

Microsoft Academic Search

Reliability is an important issue in cascaded H-bridge converters (CHB converters) because they use a high number of power semiconductors. A faulty power cell in a CHB converter can potentially lead to expensive downtime and great losses on the consumer side. With a fault-tolerant control strategy, operation can continue with the undamaged cells; thus increasing the reliability of the system.

Hossein Iman-Eini; Shahrokh Farhangi; Jean-Luc Schanen; Mahboubeh Khakbazan-Fard

2010-01-01

38

Silicon-controlled-rectifier square-wave inverter with protection against commutation failure  

NASA Technical Reports Server (NTRS)

The square-wave SCR inverter that was designed, built, and tested includes a circuit to turn off the inverter in case of commutation failure. The basic power stage is a complementary impulse-commutated parallel inverter consisting of only six components. The 400-watt breadboard was tested while operating at + or - 28 volts, and it had a peak efficiency of 95.5 percent at 60 hertz and 91.7 percent at 400 hertz. The voltage regulation for a fixed input was 3 percent at 60 hertz. An analysis of the operation and design information is included.

Birchenough, A. G.

1971-01-01

39

Silicon controlled rectifier polyphase bridge inverter commutated with gate-turn-off thyristor  

NASA Technical Reports Server (NTRS)

A polyphase SCR inverter (10) having N switching poles, each comprised of two SCR switches (1A, 1B; 2A, 2B . . . NA, NB) and two diodes (D1B; D1B; D2A, D2B . . . DNA, DNB) in series opposition with saturable reactors (L1A, L1B; L2A, L2B . . . LNA, LNB) connecting the junctions between the SCR switches and diodes to an output terminal (1, 2 . . . 3) is commutated with only one GTO thyristor (16) connected between the common negative terminal of a dc source and a tap of a series inductor (14) connected to the positive terminal of the dc source. A clamp winding (22) and diode (24) are provided, as is a snubber (18) which may have its capacitance (c) sized for maximum load current divided into a plurality of capacitors (C.sub.1, C.sub.2 . . . C.sub.N), each in series with an SCR switch S.sub.1, S.sub.2 . . . S.sub.N). The total capacitance may be selected by activating selected switches as a function of load current. A resistor 28 and SCR switch 26 shunt reverse current when the load acts as a generator, such as a motor while braking.

Edwards, Dean B. (Inventor); Rippel, Wally E. (Inventor)

1986-01-01

40

The inwardly rectifying K+ channel KIR7.1 controls uterine excitability throughout pregnancy  

PubMed Central

Abnormal uterine activity in pregnancy causes a range of important clinical disorders, including preterm birth, dysfunctional labour and post-partum haemorrhage. Uterine contractile patterns are controlled by the generation of complex electrical signals at the myometrial smooth muscle plasma membrane. To identify novel targets to treat conditions associated with uterine dysfunction, we undertook a genome-wide screen of potassium channels that are enriched in myometrial smooth muscle. Computational modelling identified Kir7.1 as potentially important in regulating uterine excitability during pregnancy. We demonstrate Kir7.1 current hyper-polarizes uterine myocytes and promotes quiescence during gestation. Labour is associated with a decline, but not loss, of Kir7.1 expression. Knockdown of Kir7.1 by lentiviral expression of miRNA was sufficient to increase uterine contractile force and duration significantly. Conversely, overexpression of Kir7.1 inhibited uterine contractility. Finally, we demonstrate that the Kir7.1 inhibitor VU590 as well as novel derivative compounds induces profound, long-lasting contractions in mouse and human myometrium; the activity of these inhibitors exceeds that of other uterotonic drugs. We conclude Kir7.1 regulates the transition from quiescence to contractions in the pregnant uterus and may be a target for therapies to control uterine contractility. PMID:25056913

McCloskey, Conor; Rada, Cara; Bailey, Elizabeth; McCavera, Samantha; van den Berg, Hugo A; Atia, Jolene; Rand, David A; Shmygol, Anatoly; Chan, Yi-Wah; Quenby, Siobhan; Brosens, Jan J; Vatish, Manu; Zhang, Jie; Denton, Jerod S; Taggart, Michael J; Kettleborough, Catherine; Tickle, David; Jerman, Jeff; Wright, Paul; Dale, Timothy; Kanumilli, Srinivasan; Trezise, Derek J; Thornton, Steve; Brown, Pamela; Catalano, Roberto; Lin, Nan; England, Sarah K; Blanks, Andrew M

2014-01-01

41

Wavelength tracking with thermally controlled silicon resonators  

E-print Network

, high-speed silicon electro-optic modulator," Opt. Express 17(25), 22484­22490 (2009). 3. M. R. Watts, D shift and the drift of laser wavelength. This feedback control scheme allows microring- based electro-optic modulators to be used in a dynamic environment. ©2011 Optical Society of America OCIS codes: (130

Mellor-Crummey, John

42

Solid state circuit controls direction, speed, and braking of dc motor  

NASA Technical Reports Server (NTRS)

Full-wave bridge rectifier circuit controls the direction, speed, and braking of a dc motor. Gating in the circuit of Silicon Controlled Rectifiers /SCRS/ controls output polarity and braking is provided by an SCR that is gated to short circuit the reverse voltage generated by reversal of motor rotation.

Hanna, M. F.

1966-01-01

43

Noise Properties of Rectifying Nanopores  

SciTech Connect

Ion currents through three types of rectifying nanoporous structures are studied and compared for the first time: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit non-equilibrium 1/f noise, thus the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, including intrinsic pore wall dynamics, and formation of vortices and non-linear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields inducing secondary effects in the pore such as enhanced water dissociation.

Powell, M R; Sa, N; Davenport, M; Healy, K; Vlassiouk, I; Letant, S E; Baker, L A; Siwy, Z S

2011-02-18

44

Noise Properties of Rectifying Nanopore  

SciTech Connect

Ion currents through three types of rectifying nanoporous structures are studied and compared: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by the power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit nonequilibrium 1/f noise; thus, the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, including intrinsic pore wall dynamics and formation of vortices and nonlinear flow patterns in the pore. Experimental data are supported by modeling of ion currents based on the coupled Poisson-Nernst-Planck and Navier-Stokes equations. We conclude that the voltage-dependent 1/f noise observed in polymer and glass asymmetric nanopores might result from high and asymmetric electric fields, inducing secondary effects in the pore, such as enhanced water dissociation.

Vlassiouk, Ivan V [ORNL

2011-01-01

45

Curvature Control of Silicon Microlens for THz Dielectric Antenna  

NASA Technical Reports Server (NTRS)

We have controlled the curvature of silicon microlens by changing the amount of photoresist in order to microfabricate hemispherical silicon microlens which can improve the directivity and reduce substrate mode losses.

Lee, Choonsup; Chattopadhyay, Goutam; Cooper, Ken; Mehdi, Imran

2012-01-01

46

Control of silicon nanoparticle size embedded in silicon oxynitride dielectric matrix  

SciTech Connect

In this study, silicon rich silicon oxynitride layers containing more than 15% nitrogen were deposited by electron cyclotron resonance assisted plasma enhanced vapor deposition in order to form silicon nanoparticles after a high temperature thermal annealing. The effect of the flows of the precursor gases on the composition and the structural properties of the layers was assessed by Rutherford backscattering spectroscopy, elastic recoil detection analysis, and infrared spectroscopic measurements. The morphological and crystallinity properties were investigated by energy filtered transmission electron microscopy and Raman spectroscopy. We show that the excess of silicon in the silicon oxynitride layer controls the silicon nanoparticles size. On the other hand, the crystalline fraction of particles is found to be strongly correlated to the nanoparticle size. Finally, the photoluminescence measurements show that it is also possible to tune the photoluminescence peak position between 400 and 800 nm and its intensity by changing the silicon excess in the silicon rich silicon oxynitride matrix.

Ehrhardt, F.; Ferblantier, G.; Muller, D.; Slaoui, A. [ICube, Strasbourg University-CNRS, 23 rue du Loess BP20, 67037 Strasbourg Cedex 2 (France); Ulhaq-Bouillet, C. [IPCMS, Strasbourg University-CNRS, 23 rue du Loess BP43, 67034 Strasbourg Cedex 2 (France); Rinnert, H. [IJL, CNRS, Campus Victor Grignard BP 70239, 54506 Vandoeuvre-les-Nancy Cedex (France)

2013-07-21

47

The study on new energy saving controller for oil-pumping units in oilfield  

Microsoft Academic Search

The energy-saving effect of Y\\/? change-over controller is better than the silicon controlled rectifier(SCR) voltage regulating style when the load rate of oil-pumping unit is low; but the silicon controlled rectifier(SCR) voltage regulating style is better than the energy-saving effect of Y\\/? change-over controller when the load rate of oil-pumping unit is high. Based on high-precision three-phase electrical energy measurement

Yan Li-mei; Xu Jian-jun; Wang Jin-liang; Xue Chen-guang; Sha Li-ni

2010-01-01

48

Artificial neural networks for control of a grid-connected rectifier/inverter under disturbance, dynamic and power converter switching conditions.  

PubMed

Three-phase grid-connected converters are widely used in renewable and electric power system applications. Traditionally, grid-connected converters are controlled with standard decoupled d-q vector control mechanisms. However, recent studies indicate that such mechanisms show limitations in their applicability to dynamic systems. This paper investigates how to mitigate such restrictions using a neural network to control a grid-connected rectifier/inverter. The neural network implements a dynamic programming algorithm and is trained by using back-propagation through time. To enhance performance and stability under disturbance, additional strategies are adopted, including the use of integrals of error signals to the network inputs and the introduction of grid disturbance voltage to the outputs of a well-trained network. The performance of the neural-network controller is studied under typical vector control conditions and compared against conventional vector control methods, which demonstrates that the neural vector control strategy proposed in this paper is effective. Even in dynamic and power converter switching environments, the neural vector controller shows strong ability to trace rapidly changing reference commands, tolerate system disturbances, and satisfy control requirements for a faulted power system. PMID:24807951

Li, Shuhui; Fairbank, Michael; Johnson, Cameron; Wunsch, Donald C; Alonso, Eduardo; Proao, Julio L

2014-04-01

49

Extending the operating range of cascaded H-bridge based multilevel rectifier under unbalanced load conditions  

Microsoft Academic Search

This paper presents a novel control strategy for cascaded H-bridge based multilevel rectifiers (CHBBR) to operate under unbalanced load and dc-bus voltage conditions. The proposed control strategy exploits the power factor as a degree of freedom to stabilize the rectifier operation. The controller is designed for single-phase seven-level rectifiers and its main feature is that it allows the multilevel rectifier

Mohammad Ali Rezaei; Shahrokh Farhangi; Hossein Iman-Eini

2010-01-01

50

Diodes and Rectifiers  

NSDL National Science Digital Library

Written by Tony R. Kuphaldt, this chapter of All About Circuit's third volume on Semiconductors describes the physics behind diodes and rectifiers. The chapter is divided into fourteen sections on topics including diode ratings, voltage multipliers, and zener diodes. Each section has clear illustrations and examples, and most have a concise, bulleted review of what was covered at the end of the page. This is an excellent resource for educators in physics and electronic engineering classrooms to introduce lessons or units on semiconductors, diodes, and rectifiers. [ASC

Kuphaldt, Tony R.

51

A low cost fuzzy logic active rectifier  

Microsoft Academic Search

This paper presents a current-sensorless active rectifier specifically designed for low cost applications. Both the control and the modulation use fuzzy logic. A simple model of the system is given in order to explain the current feedforward control using fuzzy logic and the fuzzy logic-based modulation. In this paper, the new algorithm has been deeply analysed looking to obtain the

Carlo Cecati; Antonio Dell' Aquila; Marco Liserre; Antonio Ometto

2001-01-01

52

Abstract--We are considering the problem of controlling inductions motors driven through AC/DC rectifiers and DC/AC  

E-print Network

inverter through a transformer and an AC/DC rectifier The connection line between the rectifier range regulation for the system including the AC/DC converter, the DC/AC inverter and the induction. The pollution caused by the converter may be reduced resorting to additional protection equipments (transformers

Boyer, Edmond

53

Theoretical Study of Donor - Spacer - Acceptor Structure Molecule for Molecular Rectifier  

Microsoft Academic Search

Recently, the molecular electronics has attracted strong attention as a ``post-silicone technology'' to establish a future nanoscale electronic devices. To realize this molecular device, unimolecular rectifiering function is one of the most important constituents in nanotechnology [C. Majumder, H. Mizuseki, and Y. Kawazoe, Molecular Scale Rectifier: Theoretical Study, J. Phys. Chem. A, 105 (2001) 9454-9459.]. In the present study, the

Hiroshi Mizuseki; Niimura Kenji; Rodion Belosludov; Amir Farajian; Yoshiyuki Kawazoe; C. Majumder

2003-01-01

54

Detection of diffusion welding defects by thermal NDT of rectifier elements  

Microsoft Academic Search

The possibility was investigated of applying thermal nondestructive testing to rectifying elements, because other methods of NDT (ultrasonic, radiational, electromagnetic, etc.) do not yield positive results in detecting flaws that are typical of diffusion welding. Among the findings, it is noted that optimum results are obtained when the rectifying element is heated on the side of silicon or tungsten, with

L. A. Bragina; V. P. Vavilov; A. I. Ivanov; O. M. Korolkov; G. N. Surzhenkov; E. D. Khutorianskii

1984-01-01

55

Method of controlling defect orientation in silicon crystal ribbon growth  

NASA Technical Reports Server (NTRS)

The orientation of twinning and other effects in silicon crystal ribbon growth is controlled by use of a starting seed crystal having a specific (110) crystallographic plane and (112) crystallographic growth direction.

Leipold, M. H. (inventor)

1978-01-01

56

Method and control for maintaining optimum performance of hvdc power transmission systems at rectifier end during ac system fault  

Microsoft Academic Search

A new and improved control subassembly for hvdc power converters and method of its use during transient faults affecting the ac system employed in the hvdc power transmission system are discussed. The control assures the presence of adequate firing and commutating voltages across the respective hvdc thyristor valves during selected intervals of the alternating current periods of the respective phases.

Leete

1979-01-01

57

Modelling and engineering of stress based controlled oxidation effects for silicon nanostructures  

E-print Network

Modelling and engineering of stress based controlled oxidation effects for silicon nanostructures, 59046 France E-mail: christophe.krzeminski@isen.fr Abstract. Silicon nanostructure patterning-retarded oxidation phenomenon in various silicon nanostructures (nanobeams, nanorings and nanowires) both

Paris-Sud XI, Université de

58

Black silicon with controllable macropore array for enhanced photoelectrochemical performance  

NASA Astrophysics Data System (ADS)

Macroporous silicon with multiscale texture for reflection suppression and light trapping was achieved through a controllable electrochemical etching process. It was coated with TiO2 by atomic layer deposition, and used as the photoanode in photocatalytic water splitting. A conformal pn-junction was also built-in in order to split water without external bias. A 45% enhancement in photocurrent density was observed after black silicon etching. In comparison with nano-structured silicon, the etching process here has neither metal contamination nor requirement of vacuum facilities.

Ao, Xianyu; Tong, Xili; Sik Kim, Dong; Zhang, Lianbing; Knez, Mato; Mller, Frank; He, Sailing; Schmidt, Volker

2012-09-01

59

K + channels of stomatal guard cells: Abscisic-acid-evoked control of the outward rectifier mediated by cytoplasmic pH  

Microsoft Academic Search

The activation by abscisic acid (ABA) of current through outward-rectifying K+ channels and its dependence on cytoplasmic pH (pHi) was examined in stomatal guard cells of Vicia faba L. Intact guard cells were impaled with multibarrelled and H+-selective microelectrodes to record membrane potentials and pHi during exposures to ABA and the weak acid butyrate. Potassium channel currents were monitored under

Michael R. Blatt; Fiona Armstrong

1993-01-01

60

Diameter Controlled of Carbon Nanotubes Synthesized on Nanoporous Silicon Support  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) have been successfully synthesized on nanoporous silicon template (NPSiT) using botanical source, camphor oil. Diameter of CNTs synthesized was controlled by pore size of NPSiT prepared by photo-electrochemical anodization method. The diameter of CNTs grown on different NPSiT corresponded to the pore diameter of NPSiT. FESEM images showed self-organized bundles of fiber-like structures of CNTs with diameter of around 20nm which were successfully grown directly on nanoporous silicon while raman spectra obtained ratio of ID/IG at 0.67.

Asli, N. A.; Shamsudin, M. S.; Maryam, M.; Yusop, S. F. M.; Suriani, A. B.; Rusop, M.; Abdullah, S.

2013-06-01

61

Potential for improved silicon ribbon growth through thermal environment control  

NASA Technical Reports Server (NTRS)

The Ribbon-to-Ribbon (RTR) process for growth of silicon ribbon is described. This process involves the fabrication of a microcrystalline ribbon of silicon and subsequent grain size enhancement through a laser recrystallization process. The microribbon is obtained from a Thermal Expansion Shear Separation (TESS) process which allows a CVD layer of silicon to be separated from a temporary molybdenum substrate. Efforts to achieve increased solar cell efficiencies and higher area production rates have been problematical. Furnaces, which are necessary for thermal stress control, have been shown to contribute contamination to substrates resulting in degraded efficiencies. Recent results with a new furnace design indicate efficiencies in excess of 9% will be routine. Limitations to area throughput arise due to fundamental linear velocity limitations and width limitations necessary to prevent the occurrence of thermal buckling. Calculations are reported which show the influence of thermal profile on buckling tendencies, and a proposed electron beam technique is considered which promises high throughput with minimal buckling.

Gurtler, R. W.; Baghdadi, A.; Legge, R. N.; Ellis, R. J.

1979-01-01

62

Treatment to Control Adhesion of Silicone-Based Elastomers  

NASA Technical Reports Server (NTRS)

Seals are used to facilitate the joining of two items, usually temporarily. At some point in the future, it is expected that the items will need to be separated. This innovation enables control of the adhesive properties of silicone-based elastomers. The innovation may also be effective on elastomers other than the silicone-based ones. A technique has been discovered that decreases the level of adhesion of silicone- based elastomers to negligible levels. The new technique causes less damage to the material compared to alternative adhesion mitigation techniques. Silicone-based elastomers are the only class of rubber-like materials that currently meet NASA s needs for various seal applications. However, silicone-based elastomers have natural inherent adhesive properties. This stickiness can be helpful, but it can frequently cause problems as well, such as when trying to get items apart. In the past, seal adhesion was not always adequately addressed, and has caused in-flight failures where seals were actually pulled from their grooves, preventing subsequent spacecraft docking until the seal was physically removed from the flange via an extravehicular activity (EVA). The primary method used in the past to lower elastomer seal adhesion has been the application of some type of lubricant or grease to the surface of the seal. A newer method uses ultraviolet (UV) radiation a mixture of UV wavelengths in the range of near ultraviolet (NUV) and vacuum ultraviolet (VUV) wavelengths.

deGroh, Henry C., III; Puleo, Bernadette J.; Waters, Deborah L.

2013-01-01

63

An evaluation system for experimental silicon and silicon carbide super gate turn off thyristors.  

PubMed

This paper describes the design and implementation of a small-scale pulsed power system specifically intended to evaluate the suitability of experimental silicon and silicon carbide high power Super Gate Turn Off thyristors for high action (500 A(2)?s and above) pulsed power applications where energy is extracted from a storage element in a rapid and controlled manner. To this end, six of each type of device was placed in a controlled three phase rectifier circuit which was in turn connected to an aircraft ground power motor-generator set and subjected to testing protocols with varying power levels, while parameters such as offset firing angle were varied. PMID:25085173

Bayne, Stephen; Lacouture, Shelby; Lawson, Kevin; Giesselmann, Michael; Scozzie, Charles J; O'Brien, Heather; Ogunniyi, Aderinto A

2014-07-01

64

An evaluation system for experimental silicon and silicon carbide super gate turn off thyristors  

NASA Astrophysics Data System (ADS)

This paper describes the design and implementation of a small-scale pulsed power system specifically intended to evaluate the suitability of experimental silicon and silicon carbide high power Super Gate Turn Off thyristors for high action (500 A2 s and above) pulsed power applications where energy is extracted from a storage element in a rapid and controlled manner. To this end, six of each type of device was placed in a controlled three phase rectifier circuit which was in turn connected to an aircraft ground power motor-generator set and subjected to testing protocols with varying power levels, while parameters such as offset firing angle were varied.

Bayne, Stephen; Lacouture, Shelby; Lawson, Kevin; Giesselmann, Michael; Scozzie, Charles J.; O'Brien, Heather; Ogunniyi, Aderinto A.

2014-07-01

65

Realistic-contact-induced enhancement of rectifying in carbon-nanotube/graphene-nanoribbon junctions  

SciTech Connect

Carbon-nanotube/graphene-nanoribbon junctions were recently fabricated by the controllable etching of single-walled carbon-nanotubes [Wei et al., Nat. Commun. 4, 1374 (2013)] and their electronic transport properties were studied here. First principles results reveal that the transmission function of the junctions show a heavy dependence on the shape of contacts, but rectifying is an inherent property which is insensitive to the details of contacts. Interestingly, the rectifying ratio is largely enhanced in the junction with a realistic contact and the enhancement is insensitive to the details of contact structures. The stability of rectifying suggests a significant feasibility to manufacture realistic all-carbon rectifiers in nanoelectronics.

Zhang, Xiang-Hua [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China); Department of Electrical and Information Engineering, Hunan Institute of Engineering, Xiangtan 411101 (China); Li, Xiao-Fei, E-mail: xfli@theochem.kth.se [School of Optoelectronic Information, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China); Wang, Ling-Ling, E-mail: llwang@hnu.edu.cn; Xu, Liang; Luo, Kai-Wu [School of Physics and Microelectronics Science, Hunan University, Changsha 410082 (China)

2014-03-10

66

Controlled growth of monolayer graphene on silicon carbide  

Microsoft Academic Search

Controlled thermal decomposition of silicon carbide is so far the most effective method for growing graphene epitaxially and at the wafer scale. In this work we study the graphenization of SiC(0001) and SiC(0001) as a function of temperature and buffer-gas pressure in a custom-built ultrahigh vacuum (UHV) induction furnace. In-situ characterization by both Auger electron spectroscopy and low-energy electron diffraction

David Torrance; David Miller; Madeleine Phillips; Holly Tinkey; Evan Green; Phillip First

2010-01-01

67

Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon  

SciTech Connect

Nonlinear refraction (NLR) of hydrogenated nanocrystalline silicon (nc-Si:H) has been investigated through the close aperture Z-scan method. We demonstrate a significant NLR and a unique feature of controllable NLR characteristics between saturable and Kerr NLR with the incident photon energy. We numerically evaluate the proportion of these two mechanisms in different wavelengths by a modified NLR equation. The band tail of nc-Si:H appears to play a crucial role in such NLR responses.

Zheng, D. Q.; Ye, Q. H.; Shen, W. Z., E-mail: wzshen@sjtu.edu.cn [Laboratory of Condensed Matter Spectroscopy and Opto-Electronic Physics, and Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics and Astronomy, and Institute of Solar Energy, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240 (China); Su, W. A. [Faculty of Science, Jiangxi University of Science and Technology, 86 Hong Qi Road, Ganzhou, Jiangxi 341000 (China)

2014-02-07

68

Series regulated rectifier circuit for a battery charging system  

Microsoft Academic Search

A conventional on-off voltage regulator operates a set of power mosfet switches interposed between the grounded terminal of the battery and each of the diodes of a bridge rectifier leading to that terminal. Each such switch is controlled through an individual circuit responsive to the regulator output and including an opto-electronic device controlling a thryistor which, in addition to being

W. Kurz; U. Munz

1983-01-01

69

Mechanical rectifier for micro electric generators  

Microsoft Academic Search

In this paper we propose a mechanical rectifier for micro electric generators. Since micro electric generators usually produce alternating-current power, innovation ideas for DC outputs are strongly demanded. Electric rectifiers are one of solutions; however, electric rectifier circuits using semiconductor elements have a threshold voltage. It means that the electric generator has to generate higher voltage than the threshold or

S. Nagasawa; T. Suzuki; Y. Takayama; K. Tsuji; H. Kuwano

2008-01-01

70

Nanostructured Silicon Membranes for Control of Molecular Transport  

SciTech Connect

A membrane that allows selective transport of molecular species requires precise engineering on the nanoscale. Membrane permeability can be tuned by controlling the physical structure of the pores. Here, a combination of electron-beam and optical lithography, along with cryogenic deep reactive ion etching, has been used to fabricate silicon membranes that are physically robust, have uniform pore-sizes, and are directly integrated into a microfluidic network. Additional reductions in pore size were achieved using plasma enhanced chemical vapor deposition of silicon dioxide to coat membrane surfaces. Cross sectioning of the membranes using focused ion beam milling was used to determine the physical shape of the membrane pores before and after coating.

Srijanto, Bernadeta R [ORNL] [ORNL; Retterer, Scott T [ORNL] [ORNL; Fowlkes, Jason Davidson [ORNL] [ORNL; Doktycz, Mitchel John [ORNL] [ORNL

2010-01-01

71

Crystallization of silicon nanoclusters with inert gas temperature control  

NASA Astrophysics Data System (ADS)

We analyze the fundamental process of crystallization of silicon nanoclusters by means of molecular dynamics simulations, complemented by magnetron-sputter inert gas condensation, which was used to synthesize polycrystalline silicon nanoclusters with good size control. We utilize two well-established Si interatomic potentials: the Stillinger-Weber and the Tersoff III. Both the simulations and experiments show that upon cooling down by an Ar gas thermal bath, initially liquid, free-standing Si nanocluster can grow multiple crystal nuclei, which drive their transition into polycrystalline solid nanoclusters. The simulations allow detailed analysis of the mechanism, and show that the crystallization temperature is size-dependent and that the probability of crystalline phase nucleation depends on the highest temperature the cluster reaches during the initial condensation and the cooling rate after it.

Zhao, Junlei; Singh, Vidyadhar; Grammatikopoulos, Panagiotis; Cassidy, Cathal; Aranishi, Kengo; Sowwan, Mukhles; Nordlund, Kai; Djurabekova, Flyura

2015-01-01

72

Experimental investigation of radiative thermal rectifier using vanadium dioxide  

NASA Astrophysics Data System (ADS)

Vanadium dioxide (VO2) exhibits a phase-change behavior from the insulating state to the metallic state around 340 K. By using this effect, we experimentally demonstrate a radiative thermal rectifier in the far-field regime with a thin film VO2 deposited on the silicon wafer. A rectification contrast ratio as large as two is accurately obtained by utilizing a one-dimensional steady-state heat flux measurement system. We develop a theoretical model of the thermal rectifier with optical responses of the materials retrieved from the measured mid-infrared reflection spectra, which is cross-checked with experimentally measured heat flux. Furthermore, we tune the operating temperatures by doping the VO2 film with tungsten (W). These results open up prospects in the fields of thermal management and thermal information processing.

Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo; Toshiyoshi, Hiroshi

2014-12-01

73

Physics of the frequency response of rectifying organic Schottky diodes  

NASA Astrophysics Data System (ADS)

The frequency response of unipolar organic Schottky diodes used in a rectifying circuit, such as an RFID tag, has been investigated in detail. The time dependent response of rectifying circuits has been simulated solving both the Drift Diffusion and Poisson equations to model the hole transport within the diode, coupled with time dependent circuit equations. Several approximations have also been discussed. It turns out that the cut off frequency of the rectifying circuit is indeed limited by the carrier time-of-flight and not by the diode equivalent capacitance. Simulations have also been confirmed by comparison with experiments, involving diodes with different mobilities and thicknesses. This work confirms that the 13.56 MHz frequency can be reached using polymer semiconductors, as already experimentally demonstrated in the literature, by an adequate control of the active layer thickness.

Altazin, Stphane; Clerc, Raphal; Gwoziecki, Romain; Verilhac, Jean-Marie; Boudinet, Damien; Pananakakis, Georges; Ghibaudo, Grard; Chartier, Isabelle; Coppard, Romain

2014-02-01

74

Detection of diffusion welding defects by thermal NDT of rectifier elements  

SciTech Connect

The possibility was investigated of applying thermal nondestructive testing to rectifying elements, because other methods of NDT (ultrasonic, radiational, electromagnetic, etc.) do not yield positive results in detecting flaws that are typical of diffusion welding. Among the findings, it is noted that optimum results are obtained when the rectifying element is heated on the side of silicon or tungsten, with recording of the radiation on the side of the silicon. The nature of the defects of diffusion welding is such that, no matter which method of heating is used, the defects look cooler on the thermogram. An automatic thermal flaw detector for scrapping defective rectifying elements by the method of thermal NDT is presently devised.

Bragina, L.A.; Vavilov, V.P.; Ivanov, A.I.; Korolkov, O.M.; Surzhenkov, G.N.; Khutorianskii, E.D.

1984-01-01

75

Theoretical study of donorspaceracceptor structure molecule for use as stable molecular rectifier: geometric and electronic structures  

Microsoft Academic Search

Recently, molecular electronics has attracted much attention as a post-silicon technology for future nanoscale electronic devices. One of the most important elements in molecular electronic devices is the realization of a unimolecular rectifier. In the present study, the geometric and electronic structure of the TTF-derivative (donor)sigma-bondTCNQ-derivative (acceptor), a leading candidate for a molecular rectifying device has been investigated theoretically using

H. Mizuseki; N. Igarashi; C. Majumder; R. V. Belosludov; A. A. Farajian; Y. Kawazoe

2003-01-01

76

Recruitment of G?? controls the basal activity of G-protein coupled inwardly rectifying potassium (GIRK) channels: crucial role of distal C terminus of GIRK1.  

PubMed

The G-protein coupled inwardly rectifying potassium (GIRK, or Kir3) channels are important mediators of inhibitory neurotransmission via activation of G-protein coupled receptors (GPCRs). GIRK channels are tetramers comprising combinations of subunits (GIRK1-4), activated by direct binding of the G?? subunit of Gi/o proteins. Heterologously expressed GIRK1/2 exhibit high, G??-dependent basal currents (Ibasal) and a modest activation by GPCR or coexpressed G??. Inversely, the GIRK2 homotetramers exhibit low Ibasal and strong activation by G??. The high Ibasal of GIRK1 seems to be associated with its unique distal C terminus (G1-dCT), which is not present in the other subunits. We investigated the role of G1-dCT using electrophysiological and fluorescence assays in Xenopus laevis oocytes and protein interaction assays. We show that expression of GIRK1/2 increases the plasma membrane level of coexpressed G?? (a phenomenon we term 'G?? recruitment') but not of coexpressed G?i3. All GIRK1-containing channels, but not GIRK2 homomers, recruited G?? to the plasma membrane. In biochemical assays, truncation of G1-dCT reduces the binding between the cytosolic parts of GIRK1 and G??, but not G?i3. Nevertheless, the truncation of G1-dCT does not impair activation by G??. In fluorescently labelled homotetrameric GIRK1 channels and in the heterotetrameric GIRK1/2 channel, the truncation of G1-dCT abolishes G?? recruitment and decreases Ibasal. Thus, we conclude that G1-dCT carries an essential role in G?? recruitment by GIRK1 and, consequently, in determining its high basal activity. Our results indicate that G1-dCT is a crucial part of a G?? anchoring site of GIRK1-containing channels, spatially and functionally distinct from the site of channel activation by G??. PMID:25384780

Kahanovitch, Uri; Tsemakhovich, Vladimir; Berlin, Shai; Rubinstein, Moran; Styr, Boaz; Castel, Ruth; Peleg, Sagit; Tabak, Galit; Dessauer, Carmen W; Ivanina, Tatiana; Dascal, Nathan

2014-12-15

77

Implementation issues of a fuzzy-logic-based three-phase active rectifier employing only Voltage sensors  

Microsoft Academic Search

Switch-mode rectifiers are becoming more and more interesting in those applications where bidirectional power flow, power-factor correction, and electromagnetic interference reduction are required. Typical active rectifiers include current or voltage sensors, however, in order to obtain low-cost systems, their number should be reduced. In this paper, a current-sensorless active rectifier with feedforward fuzzy logic control is presented and discussed. The

Carlo Cecati; Antonio Dell' Aquila; Agostino Lecci; Marco Liserre

2005-01-01

78

Method for rapid, controllable growth and thickness, of epitaxial silicon films  

DOEpatents

A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor deposition by controlling the rate of silicon deposition in a temperature range that spans the transition from a monohydride to a hydrogen free silicon surface in a vacuum, to obtain phase-pure epitaxial silicon film of increased thickness is disclosed. The method includes placing a c-Si substrate in a HWCVD reactor chamber. The method also includes supplying a gas containing silicon at a sufficient rate into the reaction chamber to interact with the substrate to deposit a layer containing silicon thereon at a predefined growth rate to obtain phase-pure epitaxial silicon film of increased thickness.

Wang, Qi (Littleton, CO); Stradins, Paul (Golden, CO); Teplin, Charles (Boulder, CO); Branz, Howard M. (Boulder, CO)

2009-10-13

79

Controlled growth of monolayer graphene on silicon carbide  

NASA Astrophysics Data System (ADS)

Controlled thermal decomposition of silicon carbide is so far the most effective method for growing graphene epitaxially and at the wafer scale. In this work we study the graphenization of SiC(0001) and SiC(0001) as a function of temperature and buffer-gas pressure in a custom-built ultrahigh vacuum (UHV) induction furnace. In-situ characterization by both Auger electron spectroscopy and low-energy electron diffraction (LEED) was used to determine the pressure-temperature ``phase boundary'' for the formation of monolayer graphene, and the transient growth rate of graphene layers otherwise. Sample quality was further assessed ex-situ using a variety of techniques such Raman spectroscopy and scanning tunneling microscopy. The effect of buffer gas was modeled with kinetic theory.

Torrance, David; Miller, David; Phillips, Madeleine; Tinkey, Holly; Green, Evan; First, Phillip

2010-03-01

80

Coherent Control of a Single Silicon-29 Nuclear Spin Qubit  

E-print Network

Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This work presents the first experimental detection and manipulation of a single $^{29}$Si nuclear spin. The quantum non-demolition (QND) single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of $T_2 = 6.3(7)$ ms - in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the $^{29}$Si atom under investigation. These results demonstrate that single $^{29}$Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer.

Jarryd J. Pla; Fahd A. Mohiyaddin; Kuan Y. Tan; Juan P. Dehollain; Rajib Rahman; Gerhard Klimeck; David N. Jamieson; Andrew S. Dzurak; Andrea Morello

2014-08-06

81

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2013-10-01

82

46 CFR 120.360 - Semiconductor rectifier systems.  

...2014-10-01 2014-10-01 false Semiconductor rectifier systems. 120.360 Section...Distribution Systems 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2014-10-01

83

46 CFR 183.360 - Semiconductor rectifier systems.  

...2014-10-01 2014-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2014-10-01

84

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Semiconductor rectifier systems. 120.360 Section...Distribution Systems 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2013-10-01

85

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2012-10-01

86

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Semiconductor rectifier systems. 120.360 Section...Distribution Systems 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2012-10-01

87

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2011 CFR

...Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a semiconductor rectifier system is used in a propulsion system or in other vital systems it must:...

2011-10-01

88

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2010 CFR

...Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a semiconductor rectifier system is used in a propulsion system or in other vital systems it must:...

2010-10-01

89

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2010 CFR

...Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a semiconductor rectifier system is used in a propulsion system or in other vital systems it must:...

2010-10-01

90

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2011 CFR

...Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a semiconductor rectifier system is used in a propulsion system or in other vital systems it must:...

2011-10-01

91

Precise Test of the Diffusion-Controlled Wet Isotropic Etching of Silicon via Circular Mask Openings  

Microsoft Academic Search

Isotropic etching of silicon in HF-based solutions is expected to be controlled by the diffusion of fluoride to the silicon surface. In order to gain quantitative understanding of the process, we studied etching of silicon in HF\\/HNO3\\/H2O via circular mask openings and compared the results with the theoretical expectations. The cavity edges due to etching under the mask were analyzed

V. B. Svetovoy; J. W. Berenschot; M. C. Elwenspoek

2006-01-01

92

Controlled 3D buckling of silicon nanowires for stretchable electronics.  

PubMed

Silicon (Si) nanowire (NW) coils were fabricated on elastomeric substrates by a controlled buckling process. Si NWs were first transferred onto prestrained and ultraviolet/ozone (UVO)-treated poly(dimethylsiloxane) (PDMS) substrates and buckled upon release of the prestrain. Two buckling modes (the in-plane wavy mode and the three-dimensional coiled mode) were found; a transition between them was achieved by controlling the UVO treatment of PDMS. Structural characterization revealed that the NW coils were oval-shaped. The oval-shaped NW coils exhibited very large stretchability up to the failure strain of PDMS (?104% in our study). Such a large stretchability relies on the effectiveness of the coil shape in mitigating the maximum local strain, with a mechanics that is similar to the motion of a coil spring. Single NW devices based on coiled NWs were demonstrated with a nearly constant electrical response in a large strain range. In addition to the wavy shape, the coil shape represents an effective architecture in accommodating large tension, compression, bending, and twist, which may find important applications for stretchable electronics and other stretchable technologies. PMID:21189041

Xu, Feng; Lu, Wei; Zhu, Yong

2011-01-25

93

Very low forward drop JBS rectifiers fabricated using submicron technology  

Microsoft Academic Search

Summary form only given. The impact of using submicron technology (0.5-?m design rules) on JBS (junction barrier controlled Schottky) rectifiers is examined. Two-dimensional numerical simulations demonstrate that decreasing P+-junction width and depth improves the on-state voltage drop. This is due to the improved utilization of the active area for the Schottky region and improved spreading of majority carrier current from

M. Mehrota; B. J. Baliga

1993-01-01

94

VSI-PWM rectifier\\/inverter system with a reduced switch count  

Microsoft Academic Search

A current controlled VSI-PWM rectifier and inverter with capacitor DC link is regarded as one of the most promising structures for three-phase to three-phase power conversion. This type of converter normally requires twelve switches for a rectifier and inverter composed of self turn-on switch such as a bipolar transistor or IGBT with an anti-parallel diode. In this paper, a new

Gi-Taek Kim; T.A. Lipo

1995-01-01

95

VSI-PWM rectifier\\/inverter system with a reduced switch count  

Microsoft Academic Search

A current-controlled VSI-PWM rectifier and inverter with capacitor DC link is regarded as one of the most important structures for three-phase to three-phase power conversion. This type of power converter normally requires twelve switches for the rectifier and an inverter composed of self turnoff switch such as a bipolar transistor or an IGBT with an anti-parallel diode. In this paper,

Gi-Taek Kim; Thomas A. Lipo

1996-01-01

96

Design of H-bridge multilevel active rectifier for traction systems  

Microsoft Academic Search

This paper focuses on the design of a controller for a high-voltage high-power single-phase active rectifier, designed for, but not limited to, traction field applications. The rectifier should absorb current with low harmonic content to reduce the environmental electromagnetic pollution and to eliminate the disturbances to the on-board communication equipment. In addition, it should allow the elimination of the heavy

Carlo Cecati; Antonio Dell' Aquila; Marco Liserre; Vito Giuseppe Monopoli

2003-01-01

97

A boron nitride nanotube peapod thermal rectifier  

NASA Astrophysics Data System (ADS)

The precise guidance of heat from one specific location to another is paramount in many industrial and commercial applications, including thermal management and thermoelectric generation. One of the cardinal requirements is a preferential conduction of thermal energy, also known as thermal rectification, in the materials. This study introduces a novel nanomaterial for rectifying heatthe boron nitride nanotube peapod thermal rectifier. Classical non-equilibrium molecular dynamics simulations are performed on this nanomaterial, and interestingly, the strength of the rectification phenomenon is dissimilar at different operating temperatures. This is due to the contingence of the thermal flux on the conductance at the localized region around the scatterer, which varies with temperature. The rectification performance of the peapod rectifier is inherently dependent on its asymmetry. Last but not least, the favourable rectifying direction in the nanomaterial is established.

Loh, G. C.; Baillargeat, D.

2014-06-01

98

A boron nitride nanotube peapod thermal rectifier  

SciTech Connect

The precise guidance of heat from one specific location to another is paramount in many industrial and commercial applications, including thermal management and thermoelectric generation. One of the cardinal requirements is a preferential conduction of thermal energy, also known as thermal rectification, in the materials. This study introduces a novel nanomaterial for rectifying heatthe boron nitride nanotube peapod thermal rectifier. Classical non-equilibrium molecular dynamics simulations are performed on this nanomaterial, and interestingly, the strength of the rectification phenomenon is dissimilar at different operating temperatures. This is due to the contingence of the thermal flux on the conductance at the localized region around the scatterer, which varies with temperature. The rectification performance of the peapod rectifier is inherently dependent on its asymmetry. Last but not least, the favourable rectifying direction in the nanomaterial is established.

Loh, G. C., E-mail: jgloh@mtu.edu [Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Baillargeat, D. [CNRS-International-NTU-Thales Research Alliance (CINTRA), 50 Nanyang Drive, Singapore 637553 (Singapore)

2014-06-28

99

Ultra Compact Three-phase PWM Rectifier  

Microsoft Academic Search

An increasing number of telecom, data server and aircraft power supply applications require high power, highly efficient, compact, sinusoidal input current rectifiers. The design and experimental performance of an 8.5 kW\\/liter (139 W\\/in3), 3-phase PWM rectifier with a power output of 10 kW is presented. The high power density is achieved by increasing the switching frequency up to 400 kHz,

P. Karutz; S. D. Round; M. L. Heldwein; J. W. Kolar

2007-01-01

100

Geometry control of recrystallized silicon wafers for solar applications  

E-print Network

The cost of manufacturing crystalline silicon wafers for use in solar cells can be reduced by eliminating the waste streams caused by sawing ingots into individual wafers. Professor Emanuel Sachs has developed a new method ...

Ruggiero, Christopher W

2009-01-01

101

Sized controlled synthesis, purification, and cell studies with silicon quantum dots.  

PubMed

This article describes the size control synthesis of silicon quantum dots with simple microemulsion techniques. The silicon nanocrystals are small enough to be in the strong confinement regime and photoluminesce in the blue region of the visible spectrum and the emission can be tuned by changing the nanocrystal size. The silicon quantum dots were capped with allylamine either a platinum catalyst or UV-radiation. An extensive purification protocol is reported and assessed using (1)H NMR to produce ultra pure silicon quantum dots suitable for biological studies. The highly pure quantum dots were used in cellular uptake experiments and monitored using confocal microscopy. The results showed that the amine terminated silicon nanocrystals accumulated in lysosome but not in nuclei and could be used as bio-markers to monitor cancer cells over long timescales. PMID:21727983

Shiohara, Amane; Prabakar, Sujay; Faramus, Angelique; Hsu, Chia-Yen; Lai, Ping-Shan; Northcote, Peter T; Tilley, Richard D

2011-08-01

102

Molecular orbital analysis of frontier orbitals for molecular electronics: a case study of unimolecular rectifier and photovoltaic cell  

Microsoft Academic Search

Recently, unimolecular devices have attracted significant attention as a post-silicon technology to enable the fabrication of future nanoscale electronic devices. In this paper, we describe a candidate molecule for a rectifier function using porphyrin polymer and a photovoltaic cell using fullerene-based supramolecule. We have investigated the geometric and electronic structure of these organic molecules using an ab initio quantum mechanical

Hiroshi Mizuseki; Rodion V. Belosludov; Amir A. Farajian; Nobuaki Igarashi; Jian-Tao Wang; Hao Chen; Chiranjib Majumder; Shigeyuki Miura; Yoshiyuki Kawazoe

2003-01-01

103

Modelling and engineering of stress based controlled oxidation effects for silicon nanostructure patterning  

NASA Astrophysics Data System (ADS)

Silicon nanostructure patterning with tight geometry control is an important challenge at the bottom level. In that context, stress based controlled oxidation appears to be an efficient tool for precise nanofabrication. Here, we investigate the stress-retarded oxidation phenomenon in various silicon nanostructures (nanobeams, nanorings and nanowires) at both the experimental and the theoretical levels. Different silicon nanostructures have been fabricated by a top-down approach. Complex dependence of the stress build-up on the nano-objects dimension, shape and size has been demonstrated experimentally and physically explained by modelling. For the oxidation of a two-dimensional nanostructure (nanobeam), relative independence to size effects has been observed. On the other hand, radial stress increase with geometry downscaling of a one-dimensional nanostructure (nanowire) has been carefully emphasized. The study of shape engineering by retarded oxidation effects for vertical silicon nanowires is finally discussed.

Han, Xiang-Lei; Larrieu, Guilhem; Krzeminski, Christophe

2013-12-01

104

Silicon-On-Silicon Packaging  

Microsoft Academic Search

Honeywell's new packaging technique uses silicon as a multichip substrate. Multiple integrated circuit (IC) chips are flip bonded by controlled collapse joining to a silicon substrate. The silicon substratc provides the interconnections between chips and the next level of interface. The silicon substrate is subseqently epoxy bonded to a ceramic substrate, and the package is then completed by wire bonding

R. Spielberger; C. Huang; W. Nunne; A. Mones; D. Fett; F. Hampton

1984-01-01

105

Amorphous silicon Schottky barrier solar cells incorporating a thin insulating layer and a thin doped layer  

DOEpatents

Amorphous silicon Schottky barrier solar cells which incorporate a thin insulating layer and a thin doped layer adjacent to the junction forming metal layer exhibit increased open circuit voltages compared to standard rectifying junction metal devices, i.e., Schottky barrier devices, and rectifying junction metal insulating silicon devices, i.e., MIS devices.

Carlson, David E. (Yardley, PA)

1980-01-01

106

Circuit topologies for PWM boost rectifiers operated from 1-phase and 3-phase AC supplies and using either single or split DC rail voltage outputs  

Microsoft Academic Search

This paper provides a survey of PWM boost rectifier circuit topologies for controlling a nonisolated DC-rail voltage whilst drawing supply currents at a unity fundamental power factor and with a low total harmonic distortion. Rectifier-leg topologies are classified by the number of switches and by the PWM waveforms generated. Complete rectifier circuit topologies are described for operation off 1-phase and

John C. Salmon

1995-01-01

107

Femtosecond-laser hyperdoping: controlling sulfur concentrations in silicon for band gap engineering  

NASA Astrophysics Data System (ADS)

Doping silicon to concentrations above the metal-insulator transition threshold yields a novel material that has potential for photovoltaic applications. By focusing femtosecond laser pulses on the surface of a silicon wafer in a sulfur hexafluoride (SF6) environment, silicon is doped with 1% atomic sulfur. This material exhibits near-unity, broadband absorption from the visible to the near infrared (< 0.5 eV, deep below the silicon band gap), and metallic-like conduction. These unusual optical and electronic properties suggest the formation of an intermediate band. We report on the femtosecond laser doping techniques we employ and the resulting material properties. By changing the laser parameters and ambient environment we can control the dopant profiles, crystallinity, and surface morphology. We perform optical absorption and temperature-dependent Hall measurements to investigate electron transport and to identify the energy states of the sulfur donors.

Sher, Meng-Ju; Winkler, Mark; Lin, Yu-Ting; Franta, Benjamin; Mazur, Eric

2012-02-01

108

Controlling the dopant dose in silicon by mixed-monolayer doping.  

PubMed

Molecular monolayer doping (MLD) presents an alternative to achieve doping of silicon in a nondestructive way and holds potential for realizing ultrashallow junctions and doping of nonplanar surfaces. Here, we report the mixing of dopant-containing alkenes with alkenes that lack this functionality at various ratios to control the dopant concentration in the resulting monolayer and concomitantly the dopant dose in the silicon substrate. The mixed monolayers were grafted onto hydrogen-terminated silicon using well-established hydrosilylation chemistry. Contact angle measurements, X-ray photon spectroscopy (XPS) on the boron-containing monolayers, and Auger electron spectroscopy on the phosphorus-containing monolayers show clear trends as a function of the dopant-containing alkene concentration. Dynamic secondary-ion mass spectroscopy (D-SIMS) and Van der Pauw resistance measurements on the in-diffused samples show an effective tuning of the doping concentration in silicon. PMID:25607722

Ye, Liang; Pujari, Sidharam P; Zuilhof, Han; Kudernac, Tibor; de Jong, Michel P; van der Wiel, Wilfred G; Huskens, Jurriaan

2015-02-11

109

RF sputtering for controlling dihydride and monohydride bond densities in amorphous silicon hydride  

DOEpatents

A process is described for controlling the dihydride and monohydride bond densities in hydrogenated amorphous silicone produced by reactive rf sputtering of an amorphous silicon target. There is provided a chamber with an amorphous silicon target and a substrate therein with the substrate and the target positioned such that when rf power is applied to the target the substrate is in contact with the sputtering plasma produced thereby. Hydrogen and argon are fed to the chamber and the pressure is reduced in the chamber to a value sufficient to maintain a sputtering plasma therein, and then rf power is applied to the silicon target to provide a power density in the range of from about 7 watts per square inch to about 22 watts per square inch to sputter an amorphous solicone hydride onto the substrate, the dihydride bond density decreasing with an increase in the rf power density. Substantially pure monohydride films may be produced.

Jeffery, F.R.; Shanks, H.R.

1980-08-26

110

Novel plasma control method in PECVD for preparing microcrystalline silicon  

SciTech Connect

A novel plasma enhanced vapor deposition (PECVD) technique employing biased wall (BW) method has been developed for the enhanced growth rate of the hydrogenated microcrystalline silicon ({micro}c-Si:H) films. Using this method, the authors have achieved a growth rate of more than 6{angstrom}/sec for the formation of {micro}c-Si:H having an average grain size of 200{angstrom} at 350 C.

Nishimiya, T.; Kondo, M.; Matsuda, A.

1997-07-01

111

Thermal system design and modeling of meniscus controlled silicon growth process for solar applications  

NASA Astrophysics Data System (ADS)

The direct conversion of solar radiation to electricity by photovoltaics has a number of significant advantages as an electricity generator. That is, solar photovoltaic conversion systems tap an inexhaustible resource which is free of charge and available anywhere in the world. Roofing tile photovoltaic generation, for example, saves excess thermal heat and preserves the local heat balance. This means that a considerable reduction of thermal pollution in densely populated city areas can be attained. A semiconductor can only convert photons with the energy of the band gap with good efficiency. It is known that silicon is not at the maximum efficiency but relatively close to it. There are several main parts for the photovoltaic materials, which include, single- and poly-crystalline silicon, ribbon silicon, crystalline thin-film silicon, amorphous silicon, copper indium diselenide and related compounds, cadmium telluride, et al. In this dissertation, we focus on melt growth of the single- and poly-crystalline silicon manufactured by Czochralski (Cz) crystal growth process, and ribbon silicon produced by the edge-defined film-fed growth (EFG) process. These two methods are the most commonly used techniques for growing photovoltaic semiconductors. For each crystal growth process, we introduce the growth mechanism, growth system design, general application, and progress in the numerical simulation. Simulation results are shown for both Czochralski and EFG systems including temperature distribution of the growth system, velocity field inside the silicon melt and electromagnetic field for the EFG growth system. Magnetic field is applied on Cz system to reduce the melt convection inside crucible and this has been simulated in our numerical model. Parametric studies are performed through numerical and analytical models to investigate the relationship between heater power levels and solidification interface movement and shape. An inverse problem control scheme is developed to control the solidification interface of Cz system by adjusting heater powers. For the EFG system, parametric studies are performed to discuss the effect of several growth parameters including window opening size, argon gas flow rate and growth thermal environment on the temperature distribution, silicon tube thickness and pulling rate. Two local models are developed and integrated with the global model to investigate the detailed transport phenomena in a small region around the solidification interface including silicon crystal, silicon melt, free surface, liquid-solid interface and graphite die design. Different convection forms are taken into consideration.

Wang, Chenlei

112

A motor drive control system for the Lidar Polarimeter  

E-print Network

. The advent of the silicon controlled rectifier (SCR) and modern solid state electronic had ren- dered the Ward-Leonard system obsolete. The following is an overview of the design criteria applicable to a DC variable speed motor drive with dual...A MOTOR DRIVE CONTROL SYSTEM FOR THE LIDAR POLARIMETER A Thesis by Waiming Leung Submitted to the Graduate College of Texas A/M University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCF, May 1977 Major...

Leung, Waiming

1977-01-01

113

Temperature control and characterization of silicon-germanium growth by rapid thermal chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Rapid thermal chemical vapor deposition (RTCVD) is an emerging technology to utilize low thermal budgets required to grow silicon-germanium alloys in a coherent way. However, the current state-of-the-art in RTCVD technique lacks some key elements required for acceptance of RTCVD in mainstream IC fabrication. These shortcomings include adequate control of wafer temperature during processing, and sufficient understanding of the growth kinetics. This dissertation describes and discusses the temperature control in RTCVD, the growth, and characterization of silicon-germanium alloys. The RTCVD system provides very reliable temperature-measurements, for a range of 480820C, based on infrared-light (1.3 or 1.55mum) absorption in the silicon wafer during the growth of silicon-germanium alloys. A wafer heat transfer model developed using the view-factor analysis is used to investigate temperature distributions with respect to lamp configurations in RTCVD system. For a precise temperature control, a neural model-based controller in single-input-single-output (SISO) system is proposed, and compared with other controllers. Silicon-germanium alloys, in various semiconductor structures including dots, have been grown by RTCVD where temperature is well-controlled by the model-based controller. The structural and chemical properties of silicon-germanium alloys are characterized by X-ray diffraction, atomic force microscopy (AFM), transmission electron microscopy (TEM), and secondary ion mass spectrometry (SIMS). The different growth characteristics dominated by a silicon-source gas are exploited, and their process models are developed with the experimental data utilizing neural networks employed the Bayesian framework to accurately describe the process behaviors such as growth rate and Ge fraction in alloys with respect to process variables (to capture the process nonlinearity). By controlling growth rate and Ge fraction, a uniform and a grading Ge profile in silicon-germanium layers are demonstrated for a device fabrication. In addition, a substrate dependence of growth mechanism is utilized to form dots on dielectric materials including high k materials.

Hwang, Sung-Bo

114

The Rectified Second Law of Thermodynamics  

Microsoft Academic Search

Equilibrium thermodynamics is combined with Jarzynski's irreversible work theorem to quantify the excess entropy produced by irreversible processes. The resulting rectified form of the second law parallels the first law, in the sense that it facilitates the experimental measurement of excess entropy changes resulting from irreversible work and heat exchanges, just as the first law quantifies energy changes produced by

Dor Ben-Amotz; J. M. Honig

2006-01-01

115

46 CFR 129.360 - Semiconductor-rectifier systems.  

Code of Federal Regulations, 2011 CFR

...Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a semiconductor-rectifier system is used in a propulsion system or in another vital system, it must...

2011-10-01

116

Input Impedance Modeling of Multipulse Rectifiers by Harmonic Linearization  

Microsoft Academic Search

Multipulse rectifiers are used in large industrial drives, aircraft, electric ships, and other systems, where limits on harmonic currents prohibit the use of conventional three-phase, six-pulse rectifiers. The large power rating of these rectifiers and the dynamic nature of the loads often necessitate the study of their dynamic interactions with the source, which can lead to system stability and power

Jian Sun; Zhonghui Bing; Kamiar J. Karimi

2009-01-01

117

Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens  

NASA Astrophysics Data System (ADS)

Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R.

2012-11-01

118

Advanced process control and novel test methods for PVD silicon and elastomeric silicone coatings utilized on ion implant disks, heatsinks and selected platens  

SciTech Connect

Coatings play multiple key roles in the proper functioning of mature and current ion implanters. Batch and serial implanters require strategic control of elemental and particulate contamination which often includes scrutiny of the silicon surface coatings encountering direct beam contact. Elastomeric Silicone Coatings must accommodate wafer loading and unloading as well as direct backside contact during implant plus must maintain rigid elemental and particulate specifications. The semiconductor industry has had a significant and continuous effort to obtain ultra-pure silicon coatings with sustained process performance and long life. Low particles and reduced elemental levels for silicon coatings are a major requirement for process engineers, OEM manufacturers, and second source suppliers. Relevant data will be presented. Some emphasis and detail will be placed on the structure and characteristics of a relatively new PVD Silicon Coating process that is very dense and homogeneous. Wear rate under typical ion beam test conditions will be discussed. The PVD Silicon Coating that will be presented here is used on disk shields, wafer handling fingers/fences, exclusion zones of heat sinks, beam dumps and other beamline components. Older, legacy implanters can now provide extended process capability using this new generation PVD silicon - even on implanter systems that were shipped long before the advent of silicon coating for contamination control. Low particles and reduced elemental levels are critical performance criteria for the silicone elastomers used on disk heatsinks and serial implanter platens. Novel evaluation techniques and custom engineered tools are used to investigate the surface interaction characteristics of multiple Elastomeric Silicone Coatings currently in use by the industry - specifically, friction and perpendicular stiction. These parameters are presented as methods to investigate the critical wafer load and unload function. Unique tools and test methods have been developed that deliver accurate and repeatable data, which will be described.

Springer, J.; Allen, B.; Wriggins, W.; Kuzbyt, R.; Sinclair, R. [Core Systems, 1050 Kifer Road Sunnyvale, CA 94086 (United States); FI Silicon, 1050 Kifer Road Sunnyvale, CA 94086 (United States); Core Systems, 1050 Kifer Road Sunnyvale, CA 94086 (United States)

2012-11-06

119

Flow restrictor silicon membrane microvalve actuated by optically controlled paraffin phase transition  

NASA Astrophysics Data System (ADS)

Restrictor valves allow proportional control of fluid flow but are rarely integrated in microfluidic systems. In this study, an optically actuated silicon membrane restrictor microvalve is demonstrated. Its actuation is based on the phase transition of paraffin, using a paraffin wax mixed with a suitable concentration of optically absorbing nanographite particles. Backing up the membrane with oil (the melted paraffin) allows for a compliant yet strong contact to the valve seat, which enables handling of high pressures. At flow rates up to 30?L min-1 and at a pressure of 2 bars, the valve can successfully be closed and control the flow level by restriction. The use of this paraffin composite as an adhesive layer sandwiched between the silicon valve and glass eases fabrication. This type of restrictor valve is best suited for high pressure, low volume flow silicon-based nanofluidic systems.

Kolari, K.; Havia, T.; Stuns, I.; Hjort, K.

2014-08-01

120

Control of microelectromechanical systems membrane curvature by silicon ion implantation  

NASA Astrophysics Data System (ADS)

Thin silicon membranes in microelectromechanical systems (MEMS) optical devices such as beam-steering, movable mirrors may exhibit undesirable curvature when their surface is metallized with light-reflecting metals to enhance optical performance. We have applied Si+ ion implantations at dose levels of 0.4-51016/cm2 into the gold metallization layer to successfully reduce the mirror curvature as well as the degree of its temperature-dependent changes. The curvature change as well as the temperature dependence is found to be dependent on the implantation dose. The mechanism of the observed curvature flattening effect is attributed mostly to the induced compressive stress in gold metallization caused by the insertion of foreign implanted atoms of silicon. Such a Si implantation approach can be useful as a means for post-fabrication correction of unwanted curvature in MEMS membranes, as well as a technique to intentionally introduce a desired degree of curvature if needed. A convenient blanket implantation process can be utilized with minimal contamination problems as Si is a common element already present in the MEMS.

Jin, S.; Mavoori, H.; Kim, J.; Aksyuk, V. A.

2003-09-01

121

ASIC design of color control driver for LCOS (liquid crystal on silicon) micro display  

Microsoft Academic Search

We propose the hardware design of a color control driver for the LCOS (liquid crystal on silicon) technology that will be used for the realization of advanced micro displays. The driver has been implemented and tested with an ASIC chip, and applied to actual systems like the HMDs (head mounted displays)

Jaejun Lee; Yunmo Chung; Chae-Gon Oh

2001-01-01

122

Silicon Angular Rate Sensor for Automotive Control with Open Beam Structure  

Microsoft Academic Search

An angular rate sensor of SOI (silicon on insulator) has been developed for automotive control. The sensor detects yaw rate of automobiles. The concept of the sensor design is the open beam structure (OBS). In the OBS, excitation and detection electrodes are open toward exterior bonding pads in a plane. The OBS has high independency between excitation and detection modes.

M. Fujiyoshi; Y. Nonomura; Y. Omura; N. Fujitsuka; K. Mizuno; K. Tsukada

2005-01-01

123

Control carrier recombination of multi-scale textured black silicon surface for high performance solar cells  

NASA Astrophysics Data System (ADS)

We report an enhanced performance of multi-scale textured black silicon solar cell with power conversion efficiency of 15.5% by using anisotropic tetramethylammonium hydroxide etching to control the recombination. The multi-scale texture can effectively reduce the surface reflectance in a wide wavelength range, and both the surface and Auger recombination can be effectively suppressed by etching the samples after the n++ emitter formed. Our result shows that the reformed solar cell has higher conversion efficiency than that of conventional pyramid textured cell (15.3%). This work presents an effective method for improving the performance of nanostructured silicon solar cells.

Hong, M.; Yuan, G. D.; Peng, Y.; Chen, H. Y.; Zhang, Y.; Liu, Z. Q.; Wang, J. X.; Cai, B.; Zhu, Y. M.; Chen, Y.; Liu, J. H.; Li, J. M.

2014-06-01

124

Surface photovoltage method for the quality control of silicon epitaxial layers on sapphire  

SciTech Connect

The surface photovoltage method is used to study silicon-on-sapphire epitaxial layers with a thickness of 0.30.6 ?m, which are used to fabricate p-channel MOS (metaloxide-semiconductor) transistors with improved radiation hardness. It is shown that the manner in which the photoconductivity of the epitaxial layer decays after the end of a light pulse generated by a light-emitting diode (wavelength ?400 nm) strongly depends on the density of structural defects in the bulk of the structure. This enables control over how a silicon-on-sapphire structure is formed to provide the manufacturing of MOS structures with optimal operating characteristics.

Yaremchuk, A. F.; Starkov, A. V.; Zaikin, A. V., E-mail: lynch0000@gmail.com [National Rsearch University MIET (Russian Federation); Alekseev, A. V. [ZAO Telekom-STV (Russian Federation); Sokolov, E. M. [ZAO Epiel (Russian Federation)

2014-12-15

125

Initial Rotor Position Estimation of Half-Wave Rectified Brushless Synchronous Motor  

NASA Astrophysics Data System (ADS)

This paper presents an initial rotor position estimation of Half-Wave Rectified Brushless Synchronous Motor. In the previous paper, we proposed this motor as AC servo motor, which is based on the half-wave rectified brushless excitation principle. The basic principle of this estimation technique utilizes the dependence of inductance on the rotor position. The bias frequency component of half-Wave rectified brushless excitation is used to estimate the rotor position error. The magnetic pole is discriminated by the switching condition of the diode inserted into the rotor field winding. This estimation technique is confirmed by simulation include inverter circuit, control program and motor model. Finally, the effectiveness of the proposed estimation technique has been verified by experiments.

Abe, Takashi; Oyama, Jun; Higuchi, Tsuyoshi

126

Non-invasive monitoring and control in silicon photonics by CMOS integrated electronics  

E-print Network

As photonics breaks away from today's device level toward large scale of integration and complex systems-on-a-chip, concepts like monitoring, control and stabilization of photonic integrated circuits emerge as new paradigms. Here, we show non-invasive monitoring and feedback control of high quality factor silicon photonics resonators assisted by a transparent light detector directly integrated inside the cavity. Control operations are entirely managed by a CMOS microelectronic circuit, hosting many parallel electronic read-out channels, that is bridged to the silicon photonics chip. Advanced functionalities, such as wavelength tuning, locking, labeling and swapping are demonstrated. The non-invasive nature of the transparent monitor and the scalability of the CMOS read-out system offer a viable solution for the control of arbitrarily reconfigurable photonic integrated circuits aggregating many components on a single chip.

Grillanda, Stefano; Morichetti, Francesco; Ciccarella, Pietro; Annoni, Andrea; Ferrari, Giorgio; Strain, Michael; Sorel, Marc; Sampietro, Marco; Melloni, Andrea

2014-01-01

127

Silicon-pyrene/perylene hybrids as molecular rectifiers.  

PubMed

We have synthesized two alkenyl (C-6 and C-11 chains) pyrenes and one alkenyl (C-11 chain) perylene as the ?-? systems, which were electro-grafted on H-terminated Si surfaces to form the respective monolayers. The I-V characteristics of the monolayers revealed pronounced rectification in forward bias with a maximum rectification ratio (RR) of 2.5 10(5) at 2.5 V for the C-6-pyrene 4b, 1000 at 1.5 V for the C-11-pyrene 4a and 3000-5000 at 1.75 V for the C-11-perylene 3. The higher RR of the devices containing 4b compared to those of 4a and 3 is possibly due to better alignment and packing of the 4b-monolayers on the Si substrate. The rectification was explained using the ab initio molecular-orbital calculations. PMID:25474073

Garg, Kavita; Majumder, Chiranjib; Nayak, Sandip K; Aswal, Dinesh K; Gupta, Shiv K; Chattopadhyay, Subrata

2015-01-21

128

Self-controlled fabrication of single-crystalline silicon nanobeams using conventional micromachining  

NASA Astrophysics Data System (ADS)

This paper reports on a low-cost top-down approach to the nano-precision fabrication of nanobeams on single-crystalline silicon using only conventional micromachining technology. The fabrication technique takes advantage of the crystalline structure of silicon for controllable feature size reduction of nanobeams with atomically smooth surfaces and sharp edges. Applying a deliberate rotational misalignment in a 2 ?m resolution standard lithography process, followed by anisotropic wet etching of the silicon, nanobeams with well uniform widths as small as ?85 nm are fabricated on thin SOI substrates. As a proof of concept for the incorporation of such nanobeams within electromechancial structures, we successfully demonstrate thermally actuated resonators that show very high frequencies (close to 50 MHz).

Mehdizadeh, Emad; Rahafrooz, Amir; Pourkamali, Siavash

2014-08-01

129

Coherent control of single spins in silicon carbide at room temperature.  

PubMed

Spins in solids are cornerstone elements of quantum spintronics. Leading contenders such as defects in diamond or individual phosphorus dopants in silicon have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems: it has a large bandgap with deep defects and benefits from mature fabrication techniques. Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology. PMID:25437256

Widmann, Matthias; Lee, Sang-Yun; Rendler, Torsten; Son, Nguyen Tien; Fedder, Helmut; Paik, Seoyoung; Yang, Li-Ping; Zhao, Nan; Yang, Sen; Booker, Ian; Denisenko, Andrej; Jamali, Mohammad; Momenzadeh, S Ali; Gerhardt, Ilja; Ohshima, Takeshi; Gali, Adam; Janzn, Erik; Wrachtrup, Jrg

2015-02-01

130

Coherent control of single spins in silicon carbide at room temperature  

NASA Astrophysics Data System (ADS)

Spins in solids are cornerstone elements of quantum spintronics. Leading contenders such as defects in diamond or individual phosphorus dopants in silicon have shown spectacular progress, but either lack established nanotechnology or an efficient spin/photon interface. Silicon carbide (SiC) combines the strength of both systems: it has a large bandgap with deep defects and benefits from mature fabrication techniques. Here, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that SiC is a promising system for atomic-scale spintronics and quantum technology.

Widmann, Matthias; Lee, Sang-Yun; Rendler, Torsten; Son, Nguyen Tien; Fedder, Helmut; Paik, Seoyoung; Yang, Li-Ping; Zhao, Nan; Yang, Sen; Booker, Ian; Denisenko, Andrej; Jamali, Mohammad; Momenzadeh, S. Ali; Gerhardt, Ilja; Ohshima, Takeshi; Gali, Adam; Janzn, Erik; Wrachtrup, Jrg

2015-02-01

131

Controlled growth of oriented amorphous silicon nanowires via a solidliquidsolid (SLS) mechanism  

Microsoft Academic Search

Highly oriented amorphous silicon nanowires (a-SiNWs ) were grown on Si (111). The length and diameter of oriented SiNWs are almost uniform, which are 1?m and 25nm, respectively. Different from the well-known vaporliquidsolid (VLS) for conventional whisker growth, it was found that growth of the a-SiNWs was controlled by a solidliquidsolid mechanism (SLS). This synthesis method is simple and controllable.

D. P Yu; Y. J Xing; Q. L Hang; H. F Yan; J Xu; Z. H Xi; S. Q Feng

2001-01-01

132

Formation of size controlled silicon nanocrystals in nitrogen free silicon dioxide matrix prepared by plasma enhanced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

This paper reports the growth of silicon nanocrystals (SiNCs) from SiH4-O2 plasma chemistry. The formation of an oxynitride was avoided by using O2 instead of the widely used N2O as precursor. X-ray photoelectron spectroscopy is used to prove the absence of nitrogen in the layers and determine the film stoichiometry. It is shown that the Si rich film growth is achieved via non-equilibrium deposition that resembles a interphase clusters mixture model. Photoluminescence and Fourier transformed infrared spectroscopy are used to monitor the formation process of the SiNCs, to reveal that the phase separation is completed at lower temperatures as for SiNCs based on oxynitrides. Additionally, transmission electron microscopy proves that the SiNC sizes are well controllable by superlattice configuration, and as a result, the optical emission band of the Si nanocrystal can be tuned over a wide range.

Laube, J.; Gutsch, S.; Hiller, D.; Bruns, M.; Kbel, C.; Weiss, C.; Zacharias, M.

2014-12-01

133

Optimal locomotion of mechanical rectifier systems  

NASA Astrophysics Data System (ADS)

Vehicles utilizing animal locomotion mechanisms may possess increased performance parameters and the ability to overcome more difficult terrain than conventional wheel or propeller driven vehicles. The essential mechanism underlying animal locomotion can be viewed as mechanical rectification that converts periodic body movements to thrust force through interactions with the environment. This dissertation defines a general class of mechanical rectifiers as multi-body systems equipped with such thrust generation mechanisms. A general model is developed from the Euler-Lagrange equation and simplified by assuming small body oscillations around a given nominal posture. The model reveals that the rectifying dynamics can be captured by a bilinear (but not linear) term of body shape variables. An optimal gait problem is formulated for the bilinear rectifier model as a minimization of a quadratic cost function over the set of periodic functions subject to a constraint on the average locomotion velocity. We prove that a globally optimal solution is given by a harmonic gait that can be found by generalized eigenvalue computation with a line search over cycle frequencies. We verify the solution method through case studies of a two dimensional chain of links for which snake-like undulations and jellyfish-like flapping gaits are found to be optimal, and obtain analytical insights into determinants of optimal gaits from a simple disk-mass rectifier system. Lastly, we develop a dynamic model for batoid swimming featuring a 6 degree-of-freedom main body (position and orientation), with independent wing deformation (described as the motion of many discrete points in the body-fixed coordinate frame), and calculate various gaits. Multiple wing shapes and optimality criteria are considered, such as the maximum thrust to deflection ratio or minimum input power, and the resulting gaits are compared.

Blair, Justin T.

134

Characterization of Dir: a putative potassium inward rectifying channel in Drosophila  

Microsoft Academic Search

Potassium channels vary in their function and regulation, yet they maintain a number of important features they are involved in the control of potassium flow, cell volume, cell membrane resting potential, cell excitability and hormone release. The potassium (K+) inward rectifier (Kir) superfamily of channels are potassium selective channels, that are sensitive to the concentration of K+ ions. They

Sheila J. Maclean; Bryan C. Andrews; Esther M. Verheyen

2002-01-01

135

Gene expression pattern Characterization of Dir: a putative potassium inward rectifying channel in Drosophila  

Microsoft Academic Search

Potassium channels vary in their function and regulation, yet they maintain a number of important features - they are involved in the control of potassium flow, cell volume, cell membrane resting potential, cell excitability and hormone release. The potassium (K1) inward rectifier (Kir) superfamily of channels are potassium selective channels, that are sensitive to the concentration of K1 ions. They

Sheila J. MacLean; Bryan C. Andrews; Esther M. Verheyen

136

A Multilevel Active Front-End Rectifier With Current Harmonic Compensation Capability  

E-print Network

and simultaneously as a rectifier. The control scheme is simple and forces the power system line current of this converter topology has been found in ac drives and also in reactive power compensators. Active front-q transformation requires a more complex hardware and software implementation. The power circuit topology

Catholic University of Chile (Universidad Católica de Chile)

137

Polytype control of spin qubits in silicon carbide  

NASA Astrophysics Data System (ADS)

The search for coherently addressable spin states in technologically important materials is a promising direction for solid-state quantum information science. Silicon carbide, a particularly suitable target, is not a single material but a collection of about 250 known polytypes, each with its own set of physical properties and technological applications. We show that in spite of these differences, the 4H-, 6H-, and 3C-SiC polytypes all exhibit optically addressable spins with long coherence times [1]. These results include room temperature spins in all three polytypes and suggest a new method for tuning quantum states using crystal polymorphism. Long spin coherence times allow us to use double electron-electron resonance to measure magnetic dipole interactions between spin ensembles in inequivalent lattice sites of the same crystal. Since such inequivalent spin have distinct optical and spin transition energies, these interactions could lead to dipole-coupled networks of separately addressable spins.[4pt] [1] A. Falk et al., submitted

Falk, A. L.; Buckley, B. B.; Calusine, G.; Koehl, W. F.; Politi, A.; Awschalom, D. D.; Dobrovitski, V. V.; Zorman, C. A.; Feng, P. X.-L.

2013-03-01

138

A GUI approach for control of the BELLE silicon detector data-acquisition system  

NASA Astrophysics Data System (ADS)

A graphical user interface (GUI) based control system is being built for the silicon microvertex detector (SVD) readout for the BELLE experiment at KEK. The readout system is based on a processor (Transputer) network, and is controlled through a TCP/IP connection. The control system gives users an integrated system maintenance and run control environment. The system maintenance part gives operators a user-friendly method to modify the large system and troubleshooting tools. The software has been built using a platform independent development library, and is portable between a wide range of platforms, including Unix workstations with Motif or OpenLook and Microsoft Windows.

Korhonen, Timo; Fukunaga, Chikara; Tanaka, Manobu

1996-02-01

139

Controlling the spectrum of photons generated on a silicon nanophotonic chip  

NASA Astrophysics Data System (ADS)

Directly modulated semiconductor lasers are widely used, compact light sources in optical communications. Semiconductors can also be used to generate nonclassical light; in fact, CMOS-compatible silicon chips can be used to generate pairs of single photons at room temperature. Unlike the classical laser, the photon-pair source requires control over a two-dimensional joint spectral intensity (JSI) and it is not possible to process the photons separately, as this could destroy the entanglement. Here we design a photon-pair source, consisting of planar lightwave components fabricated using CMOS-compatible lithography in silicon, which has the capability to vary the JSI. By controlling either the optical pump wavelength, or the temperature of the chip, we demonstrate the ability to select different JSIs, with a large variation in the Schmidt number. Such control can benefit high-dimensional communications where detector-timing constraints can be relaxed by realizing a large Schmidt number in a small frequency range.

Kumar, Ranjeet; Ong, Jun Rong; Savanier, Marc; Mookherjea, Shayan

2014-11-01

140

Diameter-controlled synthesis of single-crystal silicon nanowires Yi Cui, Lincoln J. Lauhon, Mark S. Gudiksen, Jianfang Wang,  

E-print Network

Diameter-controlled synthesis of single-crystal silicon nanowires Yi Cui, Lincoln J. Lauhon, Mark S Monodisperse silicon nanowires were synthesized by exploiting well-defined gold nanoclusters as catalysts nm. © 2001 American Institute of Physics. DOI: 10.1063/1.1363692 The synthesis and characterization

Cui, Yi

141

Threshold Crack Speed Controls Dynamical Fracture of Silicon Single Crystals Markus J. Buehler,1,* Harvey Tang,2  

E-print Network

Threshold Crack Speed Controls Dynamical Fracture of Silicon Single Crystals Markus J. Buehler,1 of single silicon crystals reveal that after the critical fracture load is reached, the crack speed jumps from zero to 2 km= sec, indicating that crack motion at lower speeds is forbidden. This contradicts

Goddard III, William A.

142

Production of low cost silicon wafers by continuous casting method-development of drip-controlled method  

Microsoft Academic Search

The continuous casting method (CCM) has been designed to obtain low cost silicon wafers. This method has the objective of wafer cost reduction production effect through the installation of a pre-heating zone and a crystal growth and cooling zone separately on both sides of a silicon melting and injecting zone. We have developed the drip-controlled method (DCM) as a casting

S. Goda; T. Moritani; Y. Hatanaka; H. Shimizu; I. Hide

1994-01-01

143

Water/glycol temperature control circuit failed in the automatic mode: Apollo 16  

NASA Technical Reports Server (NTRS)

An anomaly report concerning failure of the water/glycol temperature control circuit during the Apollo 16 flight is presented. The anomaly is described and diagrams of the system are presented. The malfunction was caused by cracked semiconductor chips in the output silicon-controlled rectifier. Surface contamination in the crack allowed the device to self-gate on and remain on, resulting in a secondary failure of the feedback capacitor.

1972-01-01

144

The graded doped trench MOS Barrier Schottky rectifier: a low forward drop high voltage rectifier  

NASA Astrophysics Data System (ADS)

A novel high voltage Schottky rectifier, called the Graded Doped Trench MOS Barrier Schottky (GD-TMBS) rectifier, is described in this paper. It is shown to have very low forward drop with excellent reverse blocking characteristics through device simulation and electrical characterization of fabricated devices. A linearly graded drift region doping profile is shown to result in an uniform electric field in the drift region resulting in the ability to support blocking voltages proportional to the trench depth. Two-dimensional device simulations have shown that breakdown voltages of upto 200 V can be achieved with a very low forward drop of 0.54 V. The measured on-state drop of fabricated 60 and 100 V GD-TMBS are about half those of conventional Schottky rectifiers. Power dissipation analysis indicates higher operating temperatures (150C) with reduced heat sink sizes when compared to conventional Schottky barrier diodes.

Mahalingam, Srikanth; Baliga, B. Jayant

1999-01-01

145

Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz  

NASA Technical Reports Server (NTRS)

A group at UCLA, in collaboration with the Jet Propulsion Laboratory, has designed a voltage-controlled oscillator (VCO) created specifically for a compact, integrated, electronically tunable frequency generator useable for submillimeter- wave science instruments operating in extreme cold environments.

Wong, Alden; Larocca, Tim; Chang, M. Frank; Samoska, Lorene A.

2011-01-01

146

Measurement and Control of In-plane Surface Chemistry at the Silicon/Silicon Dioxide Interface  

NASA Astrophysics Data System (ADS)

In-plane directional control of surface chemistry during interface formation can lead to new opportunities regarding device structures and applications. Control of this type requires techniques that can probe and hence provide feedback on the chemical reactivity of bonds not only in specific directions but also in real time. In this thesis work, I demonstrate both control and measurement of the oxidation of H-terminated Si(111). The nonlinear optical tool of Second-Harmonic-Generation (SHG) is used to show that Si oxidation in air is a two-stage process where the H of the "up" bonds of the outermost Si layer is replaced by OH, followed by O insertion into the "back" bonds. Detailed information about both stages is revealed by investigating the effect of uniaxial strain and carrier concentration on this chemical reaction. It is shown that even small amounts of strain manipulate the reaction kinetics of surface bonds significantly, with tensile strain enhancing oxidation and compressive strain retarding it. This dramatic change suggests a strain-driven charge transfer mechanism between Si--H up bonds and Si--Si back bonds in the outer layer of Si atoms. Data on differently doped samples reveal that high concentrations of electrons increase the chemical reactivity of the outer-layer Si--Si back bonds relative to the Si--H up bonds while high concentrations of holes cause a greater increase in the reactivity of the Si--H up bonds than that of the Si--Si back bonds. However, the thicknesses of the natural oxides of all samples follow the same path and stabilize near 1 nm at room temperature, regardless of the chemical kinetics of the different bonds, as determined by spectroscopic ellipsometry. Real-time measurement during SHG experiments is achieved by analyzing SHG anisotropy data with the anisotropic bond-charge model of nonlinear optics where peaks in the SHG spectrum are correlated with the near alignment of bonds to the direction of the excitation field.

Gokce, Bilal

147

Accurate method for neutron fluence control used in improving neutron-transmutation-doped silicon for detectors  

NASA Astrophysics Data System (ADS)

Neutron transmutation doping (NTD) of silicon (Si) in nuclear reactors is known as a successful way of obtaining high-quality material for power devices. Using NTD of Si in order to obtain high-quality material for detectors requires an accurate neutron fluence control. The paper presents results obtained in this field using silicon slices as neutron calibration material. Irradiation was done in a vertical channel of the VVR-S nuclear reactor in Bucharest, Romania. Final resistivity of slices used for calibration was between 20 and 50 ohm X cm. Special attention was paid to the accuracy of initial and final characterization of the slices concerning resistivity, lifetime, and defects, as well as to the neutron fluence calibration and control used during exposure. High-performance detectors were obtained using this material.

Halmagean, Eugenia T.; Lazarovici, Doina N.; Udrea-Spinea, Marian N.

1991-08-01

148

Controlled growth of monolayer graphene on silicon carbide in argon atmosphere  

Microsoft Academic Search

Controlled thermal decomposition of silicon carbide is so far the most effective method for growing graphene epitaxially and at the wafer scale. In this work we study the graphenization of SiC(0001) and SiC(0001) as a function of ambient argon pressure and temperature in a custom-built ultrahigh vacuum (UHV) induction furnace. In-situ characterization by both Auger electron spectroscopy and low-energy electron

David Torrance; David Miller; Holly Tinkey; Evan Green; Madeleine Phillips; Phillip First

2009-01-01

149

High precision quantum control of single donor spins in silicon  

E-print Network

The Stark shift of the hyperfine coupling constant is investigated for a P donor in Si far below the ionization regime in the presence of interfaces using Tight-binding and Band Minima Basis approaches and compared to the recent precision measurements. The TB electronic structure calculations included over 3 million atoms. In contrast to previous effective mass based results, the quadratic Stark coefficient obtained from both theories agrees closely with the experiments. This work represents the most sensitive and precise comparison between theory and experiment for single donor spin control. It is also shown that there is a significant linear Stark effect for an impurity near the interface, whereas, far from the interface, the quadratic Stark effect dominates. Such precise control of single donor spin states is required particularly in quantum computing applications of single donor electronics, which forms the driving motivation of this work.

Rajib Rahman; Cameron J. Wellard; Forrest R. Bradbury; Marta Prada; Jared H. Cole; Gerhard Klimeck; Lloyd C. L. Hollenberg

2007-05-15

150

A Silicon Implementation of the Fly's Optomotor Control System  

Microsoft Academic Search

Flies are capable of stabilizing their body during free flight by using visual motion information to estimate self-rotation. We have built a hard- ware model of this optomotor control system in a standard CMOS VLSI process. The result is a small, low-power chip that receives input directly from the real world through on-board photoreceptors and generates mo- tor commands in

Reid R. Harrison; Christof Koch

2000-01-01

151

Theoretical Study of Donor - Spacer - Acceptor Structure Molecule for Molecular Rectifier  

NASA Astrophysics Data System (ADS)

Recently, the molecular electronics has attracted strong attention as a ``post-silicone technology'' to establish a future nanoscale electronic devices. To realize this molecular device, unimolecular rectifiering function is one of the most important constituents in nanotechnology [C. Majumder, H. Mizuseki, and Y. Kawazoe, Molecular Scale Rectifier: Theoretical Study, J. Phys. Chem. A, 105 (2001) 9454-9459.]. In the present study, the geometric and electronic structure of alkyl derivative C37H50N4O4 (PNX) molecule, (donor - spacer - acceptor), a leading candidate of molecular rectifying device, has been investigated theoretically using ab initio quantum mechanical calculation. The results suggest that in such donor-acceptor molecular complexes, while the lowest unoccupied orbital concentrates on the acceptor subunit, the highest occupied molecular orbital is localized on the donor subunit. The approximate potential differences for optimized PNX molecule have been estimated at the B3PW91/6-311g++(d,p) level of theory, which achieves quite good agreement with experimentally reported results. This study was performed through Special Coordination Funds for Promoting Science and Technology of the Ministry of Education, Culture, Sports, Science and Technology of the Japanese Government.

Mizuseki, Hiroshi; Kenji, Niimura; Belosludov, Rodion; Farajian, Amir; Kawazoe, Yoshiyuki

2003-03-01

152

Development of high temperature gallium phosphide rectifiers  

NASA Technical Reports Server (NTRS)

Large area high performance, GaP rectifiers were fabricated by means of Zn diffusion into vapor phase epitaxial GaP. Devices with an active area of 0.01 sq cm typically exhibit forward voltages of 3 volts for a bias current of 1 ampere and have reverse breakdown voltages of 300 volts for temperatures from 27 C to 400 C. Typical device reverse saturation current at a reverse bias of 150 volts is less than 10 to the minus 9th power amp at 27 C and less than 0.000050 amp at 400 C.

Craford, M. G.; Keune, D. L.

1972-01-01

153

Quantum Entanglement and Spin Control in Silicon Nanocrystal  

PubMed Central

Selective coherence control and electrically mediated exchange coupling of single electron spin between triplet and singlet states using numerically derived optimal control of proton pulses is demonstrated. We obtained spatial confinement below size of the Bohr radius for proton spin chain FWHM. Precise manipulation of individual spins and polarization of electron spin states are analyzed via proton induced emission and controlled population of energy shells in pure 29Si nanocrystal. Entangled quantum states of channeled proton trajectories are mapped in transverse and angular phase space of 29Si axial channel alignment in order to avoid transversal excitations. Proton density and proton energy as impact parameter functions are characterized in single particle density matrix via discretization of diagonal and nearest off-diagonal elements. We combined high field and low densities (1 MeV/92 nm) to create inseparable quantum state by superimposing the hyperpolarizationed proton spin chain with electron spin of 29Si. Quantum discretization of density of states (DOS) was performed by the Monte Carlo simulation method using numerical solutions of proton equations of motion. Distribution of gaussian coherent states is obtained by continuous modulation of individual spin phase and amplitude. Obtained results allow precise engineering and faithful mapping of spin states. This would provide the effective quantum key distribution (QKD) and transmission of quantum information over remote distances between quantum memory centers for scalable quantum communication network. Furthermore, obtained results give insights in application of channeled protons subatomic microscopy as a complete versatile scanning-probe system capable of both quantum engineering of charged particle states and characterization of quantum states below diffraction limit linear and in-depth resolution. PACS numbers: 03.65.Ud, 03.67.Bg, 61.85.+p, 67.30.hj PMID:23028884

Berec, Vesna

2012-01-01

154

Fabrication of disposable topographic silicon oxide from sawtoothed patterns: control of arrays of gold nanoparticles.  

PubMed

Disposable topographic silicon oxide patterns were fabricated from polymeric replicas of sawtoothed glass surfaces, spin-coating of poly(dimethylsiloxane) (PDMS) thin films, and thermal annealing at certain temperature and followed by oxygen plasma treatment of the thin PDMS layer. A simple imprinting process was used to fabricate the replicated PDMS and PS patterns from sawtoothed glass surfaces. Next, thin layers of PDMS films having different thicknesses were spin-coated onto the sawtoothed PS surfaces and annealed at 60 degrees C to be drawn the PDMS into the valley of the sawtoothed PS surfaces, followed by oxygen plasma treatment to fabricate topographic silicon oxide patterns. By control of the thickness of PDMS layers, silicon oxide patterns having various line widths were fabricated. The silicon oxide topographic patterns were used to direct the self-assembly of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer thin films via solvent annealing process. A highly ordered PS-b-P2VP micellar structure was used to let gold precursor complex with P2VP chains, and followed by oxygen plasma treatment. When the PS-b-P2VP thin films containing gold salts were exposed to oxygen plasma environments, gold salts were reduced to pure gold nanoparticles without changing high degree of lateral order, while polymers were completely degraded. As the width of trough and crest in topographic patterns increases, the number of gold arrays and size of gold nanoparticles are tuned. In the final step, the silicon oxide topographic patterns were selectively removed by wet etching process without changing the arrays of gold nanoparticles. PMID:20000759

Cho, Heesook; Yoo, Hana; Park, Soojin

2010-05-18

155

Engineering of silicon surfaces at the micro- and nanoscales for cell adhesion and migration control  

PubMed Central

The engineering of surface patterns is a powerful tool for analyzing cellular communication factors involved in the processes of adhesion, migration, and expansion, which can have a notable impact on therapeutic applications including tissue engineering. In this regard, the main objective of this research was to fabricate patterned and textured surfaces at micron- and nanoscale levels, respectively, with very different chemical and topographic characteristics to control cellsubstrate interactions. For this task, one-dimensional (1-D) and two-dimensional (2-D) patterns combining silicon and nanostructured porous silicon were engineered by ion beam irradiation and subsequent electrochemical etch. The experimental results show that under the influence of chemical and morphological stimuli, human mesenchymal stem cells polarize and move directionally toward or away from the particular stimulus. Furthermore, a computational model was developed aiming at understanding cell behavior by reproducing the surface distribution and migration of human mesenchymal stem cells observed experimentally. PMID:22346355

Torres-Costa, Vicente; Martnez-Muoz, Gonzalo; Snchez-Vaquero, Vanessa; Muoz-Noval, lvaro; Gonzlez-Mndez, Laura; Punzn-Quijorna, Esther; Gallach-Prez, Daro; Manso-Silvn, Miguel; Climent-Font, Aurelio; Garca-Ruiz, Josefa P; Martn-Palma, Ral J

2012-01-01

156

Controlling the Er content of porous silicon using the doping current intensity  

PubMed Central

The results of an investigation on the Er doping of porous silicon are presented. Electrochemical impedance spectroscopy, optical reflectivity, and spatially resolved energy dispersive spectroscopy (EDS) coupled to scanning electron microscopy measurements were used to investigate on the transient during the first stages of constant current Er doping. Depending on the applied current intensity, the voltage transient displays two very different behaviors, signature of two different chemical processes. The measurements show that, for equal transferred charge and identical porous silicon (PSi) layers, the applied current intensity also influences the final Er content. An interpretative model is proposed in order to describe the two distinct chemical processes. The results can be useful for a better control over the doping process. PACS 81.05.Rm; 82.45.Rr PMID:25024691

2014-01-01

157

Conditional control of donor nuclear spins in silicon using stark shifts.  

PubMed

Electric fields can be used to tune donor spins in silicon using the Stark shift, whereby the donor electron wave function is displaced by an electric field, modifying the hyperfine coupling between the electron spin and the donor nuclear spin. We present a technique based on dynamic decoupling of the electron spin to accurately determine the Stark shift, and illustrate this using antimony donors in isotopically purified silicon-28. We then demonstrate two different methods to use a dc electric field combined with an applied resonant radio-frequency (rf) field to conditionally control donor nuclear spins. The first method combines an electric-field induced conditional phase gate with standard rf pulses, and the second one simply detunes the spins off resonance. Finally, we consider different strategies to reduce the effect of electric field inhomogeneities and obtain above 90% process fidelities. PMID:25375741

Wolfowicz, Gary; Urdampilleta, Matias; Thewalt, Mike L W; Riemann, Helge; Abrosimov, Nikolai V; Becker, Peter; Pohl, Hans-Joachim; Morton, John J L

2014-10-10

158

Fabrication of ultrathin and highly uniform silicon on insulator by numerically controlled plasma chemical vaporization machining  

NASA Astrophysics Data System (ADS)

Metal-oxide semiconductor field-effect transistors fabricated on a silicon-on-insulator (SOI) wafer operate faster and at a lower power than those fabricated on a bulk silicon wafer. Scaling down, which improves their performances, demands thinner SOI wafers. In this article, improvement on the thinning of SOI wafers by numerically controlled plasma chemical vaporization machining (PCVM) is described. PCVM is a gas-phase chemical etching method in which reactive species generated in atmospheric-pressure plasma are used. Some factors affecting uniformity are investigated and methods for improvements are presented. As a result of thinning a commercial 8in. SOI wafer, the initial SOI layer thickness of 97.54.7nm was successfully thinned and made uniform at 7.51.5nm.

Sano, Yasuhisa; Yamamura, Kazuya; Mimura, Hidekazu; Yamauchi, Kazuto; Mori, Yuzo

2007-08-01

159

Fabrication of ultrathin and highly uniform silicon on insulator by numerically controlled plasma chemical vaporization machining.  

PubMed

Metal-oxide semiconductor field-effect transistors fabricated on a silicon-on-insulator (SOI) wafer operate faster and at a lower power than those fabricated on a bulk silicon wafer. Scaling down, which improves their performances, demands thinner SOI wafers. In this article, improvement on the thinning of SOI wafers by numerically controlled plasma chemical vaporization machining (PCVM) is described. PCVM is a gas-phase chemical etching method in which reactive species generated in atmospheric-pressure plasma are used. Some factors affecting uniformity are investigated and methods for improvements are presented. As a result of thinning a commercial 8 in. SOI wafer, the initial SOI layer thickness of 97.5+/-4.7 nm was successfully thinned and made uniform at 7.5+/-1.5 nm. PMID:17764362

Sano, Yasuhisa; Yamamura, Kazuya; Mimura, Hidekazu; Yamauchi, Kazuto; Mori, Yuzo

2007-08-01

160

Gate-controlled-diodes in silicon-on-sapphire: A computer simulation  

NASA Technical Reports Server (NTRS)

The computer simulation of the electrical behavior of a Gate-Controlled Diode (GCD) fabricated in Silicon-On-Sapphire (SOS) was described. A procedure for determining lifetime profiles from capacitance and reverse current measurements on the GCD was established. Chapter 1 discusses the SOS structure and points out the need of lifetime profiles to assist in device design for GCD's and bipolar transistors. Chapter 2 presents the one-dimensional analytical formula for electrostatic analysis of the SOS-GCD which are useful for data interpretation and setting boundary conditions on a simplified two-dimensional analysis. Chapter 3 gives the results of a two-dimensional analysis which treats the field as one-dimensional until the silicon film is depleted and the field penetrates the sapphire substrate. Chapter 4 describes a more complete two-dimensional model and gives results of programs implementing the model.

Gassaway, J. D.

1974-01-01

161

Outwardly rectifying chloride channels and CF: A divorce and remarriage  

Microsoft Academic Search

Outwardly rectifying Cl- channels were originally thought to be the central element in cystic fibrosis. The role of these channels in CF was questioned to such an extent that doubts were rasied about the validity of the original experiments. Recent data reestablishes a role for outwardly rectifying Cl- channels (ORCC) in CF and suggests that the protein encoded by the

William B. Guggino

1993-01-01

162

The effects of DC ripple from cathodic protection rectifiers  

SciTech Connect

The phenomenon of ripple in Direct Current Cathodic Protection (CP) circuits, resulting from the use of single phase Alternating Current (AC) rectifiers, is not well understood by most cathodic protection personnel. This paper discusses studies conducted in an attempt to verify the existence and magnitude of this ripple and differences in corrosion rates, if any, between filtered and unfiltered rectified DC current.

Pellet, L.A. [Pellet (Louis A.), Houston, TX (United States); Koenig, R. [Koenig (Richard), Houston, TX (United States)

1998-12-31

163

A molecular half-wave rectifier.  

PubMed

This paper describes the performance of junctions based on self-assembled monolayers (SAMs) as the functional element of a half-wave rectifier (a simple circuit that converts, or rectifies, an alternating current (AC) signal to a direct current (DC) signal). Junctions with SAMs of 11-(ferrocenyl)-1-undecanethiol or 11-(biferrocenyl)-1-undecanethiol on ultraflat, template-stripped Ag (Ag(TS)) bottom electrodes, and contacted by top electrodes of eutectic indium-gallium (EGaIn), rectified AC signals, while similar junctions based on SAMs of 1-undecanethiol-SAMs lacking the ferrocenyl terminal group-did not. SAMs in these AC circuits (operating at 50 Hz) remain stable over a larger window of applied bias than in DC circuits. AC measurements, therefore, can investigate charge transport in SAM-based junctions at magnitudes of bias inaccessible to DC measurements. For junctions with SAMs of alkanethiols, combining the results from AC and DC measurements identifies two regimes of bias with different mechanisms of charge transport: (i) low bias (|V| < 1.3 V), at which direct tunneling dominates, and (ii) high bias (|V| > 1.3 V), at which Fowler-Nordheim (FN) tunneling dominates. For junctions with SAMs terminated by Fc moieties, the transition to FN tunneling occurs at |V| ? 2.0 V. Furthermore, at sufficient forward bias (V > 0.5 V), hopping makes a significant contribution to charge transport and occurs in series with direct tunneling (V ? 2.0 V) until FN tunneling activates (V ? 2.0 V). Thus, for Fc-terminated SAMs at forward bias, three regimes are apparent: (i) direct tunneling (V = 0-0.5 V), (ii) hopping plus direct tunneling (V ? 0.5-2.0 V), and (iii) FN tunneling (V ? 2.0 V). Since hopping does not occur at reverse bias, only two regimes are present over the measured range of reverse bias. This difference in the mechanisms of charge transport at forward and reverse bias for junctions with Fc moieties resulted in large rectification ratios (R > 100) and enabled half-wave rectification. PMID:21842878

Nijhuis, Christian A; Reus, William F; Siegel, Adam C; Whitesides, George M

2011-10-01

164

Control of crystalline volume and nano crystal grain size in nanocrystalline silicon thin film deposited by PECVD  

NASA Astrophysics Data System (ADS)

Application of the radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) technique was studied to fabricate amorphous and nanocrystalline silicon (a-Si and nc-Si) thin films for photovoltaic devices at substrate temperature of 200 C. Amorphous-crystalline transition of silicon thin films in working conditions of PECVD system was shown as a function of deposition parameters, i.e., dilution ratio of silane (SiH4) in hydrogen, total gas pressure during deposition and RF excitation power density. The crystalline volume as well as grain size of nanocrystalline silicon films could be successfully controlled by tuning those deposition parameters. Micro Raman scattering spectroscopy and spectroscopic ellipsometry (SE) methods were used to characterize the structure and crystallization of the deposited silicon thin films. We could make nc-Si thin films with various crystalline volumes. Nc-Si grain size was also controlled and was in the range of 3-5 nm.

Bui, Thanh Tung; Chien Dang, Mau

2014-11-01

165

Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures  

SciTech Connect

Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

2002-04-01

166

Spatial properties of rectified cosine Gaussian beams  

NASA Astrophysics Data System (ADS)

The cosine Gaussian beam (CGB) resulting from the coherent coaxial superposition of two Gaussian beams having the same width W and opposite radii of curvature R and - R is a ringed beam characterized by an M2 factor which can be very high, and adjustable by changing R. According to the paper by Hasnaoui et al(2011 Opt. Commun.284 1331-4) we expect that the CGB after rectification by a binary diffractive optical element could be a good candidate for focal volume reduction, so useful to many laser applications. Unfortunately, this is not the case, and the physical factors responsible for this unexpected behaviour have been analysed. In particular, we have demonstrated that the three features (M2 factor, divergence and on-axis intensity) do not hold the same information about the spatial characteristics of rectified or unrectified CGBs.

Boubaha, B.; Bencheikh, A.; At-Ameur, K.

2014-02-01

167

Large area and structured epitaxial graphene produced by confinement controlled sublimation of silicon carbide  

PubMed Central

After the pioneering investigations into graphene-based electronics at Georgia Tech, great strides have been made developing epitaxial graphene on silicon carbide (EG) as a new electronic material. EG has not only demonstrated its potential for large scale applications, it also has become an important material for fundamental two-dimensional electron gas physics. It was long known that graphene mono and multilayers grow on SiC crystals at high temperatures in ultrahigh vacuum. At these temperatures, silicon sublimes from the surface and the carbon rich surface layer transforms to graphene. However the quality of the graphene produced in ultrahigh vacuum is poor due to the high sublimation rates at relatively low temperatures. The Georgia Tech team developed growth methods involving encapsulating the SiC crystals in graphite enclosures, thereby sequestering the evaporated silicon and bringing growth process closer to equilibrium. In this confinement controlled sublimation (CCS) process, very high-quality graphene is grown on both polar faces of the SiC crystals. Since 2003, over 50 publications used CCS grown graphene, where it is known as the furnace grown graphene. Graphene multilayers grown on the carbon-terminated face of SiC, using the CCS method, were shown to consist of decoupled high mobility graphene layers. The CCS method is now applied on structured silicon carbide surfaces to produce high mobility nano-patterned graphene structures thereby demonstrating that EG is a viable contender for next-generation electronics. Here we present for the first time the CCS method that outperforms other epitaxial graphene production methods. PMID:21960446

de Heer, Walt A.; Berger, Claire; Ruan, Ming; Sprinkle, Mike; Li, Xuebin; Hu, Yike; Zhang, Baiqian; Hankinson, John; Conrad, Edward

2011-01-01

168

Frequency Dependence of Amorphous Silicon Schottky Diodes for Large-Area Rectification Applications  

E-print Network

Frequency Dependence of Amorphous Silicon Schottky Diodes for Large-Area Rectification Applications on hydrogenated amorphous silicon (a-Si:H); 2) circuit design strategies for using the diodes at frequencies far of out knowledge, the first amorphous silicon (a Si:H) full-wave rectifier, with an AC-to-DC power

169

Improved quality control of silicon wafers using novel off-line air pocket image analysis  

NASA Astrophysics Data System (ADS)

Air pockets (APK) occur randomly in Czochralski (Cz) grown silicon (Si) crystals and may become included in wafers after slicing and polishing. Previously the only APK of interest were those that intersected the front surface of the wafer and therefore directly impacted device yield. However mobile and other electronics have placed new demands on wafers to be internally APK-free for reasons of thermal management and packaging yield. We present a novel, recently patented, APK image processing technique and demonstrate the use of that technique, off-line, to improve quality control during wafer manufacturing.

Valley, John F.; Sanna, M. Cristina

2014-08-01

170

Precise control of the coupling coefficient through destructive interference in silicon waveguide Bragg gratings.  

PubMed

We present waveguide Bragg gratings with misaligned sidewall corrugations on a silicon-on-insulator platform. The grating strength can be tuned by varying the misalignment between the corrugations on the two sidewalls. This approach allows for a wide range of grating coupling coefficients to be achieved with precise control, and substantially reduces the effects of quantization error due to the finite mask grid size. The experimental results are in very good agreement with simulations using the finite-difference time-domain (FDTD) method. PMID:25360917

Wang, Xu; Wang, Yun; Flueckiger, Jonas; Bojko, Richard; Liu, Amy; Reid, Adam; Pond, James; Jaeger, Nicolas A F; Chrostowski, Lukas

2014-10-01

171

Controlling the spectrum of photons generated on a silicon nanophotonic chip  

PubMed Central

Directly modulated semiconductor lasers are widely used, compact light sources in optical communications. Semiconductors can also be used to generate nonclassical light; in fact, CMOS-compatible silicon chips can be used to generate pairs of single photons at room temperature. Unlike the classical laser, the photon-pair source requires control over a two-dimensional joint spectral intensity (JSI) and it is not possible to process the photons separately, as this could destroy the entanglement. Here we design a photon-pair source, consisting of planar lightwave components fabricated using CMOS-compatible lithography in silicon, which has the capability to vary the JSI. By controlling either the optical pump wavelength, or the temperature of the chip, we demonstrate the ability to select different JSIs, with a large variation in the Schmidt number. Such control can benefit high-dimensional communications where detector-timing constraints can be relaxed by realizing a large Schmidt number in a small frequency range. PMID:25410792

Kumar, Ranjeet; Ong, Jun Rong; Savanier, Marc; Mookherjea, Shayan

2014-01-01

172

Controlling the spectrum of photons generated on a silicon nanophotonic chip.  

PubMed

Directly modulated semiconductor lasers are widely used, compact light sources in optical communications. Semiconductors can also be used to generate nonclassical light; in fact, CMOS-compatible silicon chips can be used to generate pairs of single photons at room temperature. Unlike the classical laser, the photon-pair source requires control over a two-dimensional joint spectral intensity (JSI) and it is not possible to process the photons separately, as this could destroy the entanglement. Here we design a photon-pair source, consisting of planar lightwave components fabricated using CMOS-compatible lithography in silicon, which has the capability to vary the JSI. By controlling either the optical pump wavelength, or the temperature of the chip, we demonstrate the ability to select different JSIs, with a large variation in the Schmidt number. Such control can benefit high-dimensional communications where detector-timing constraints can be relaxed by realizing a large Schmidt number in a small frequency range. PMID:25410792

Kumar, Ranjeet; Ong, Jun Rong; Savanier, Marc; Mookherjea, Shayan

2014-01-01

173

Silicon microgyroscope temperature prediction and control system based on BP neural network and Fuzzy-PID control method  

NASA Astrophysics Data System (ADS)

We present a novel silicon microgyroscope (SMG) temperature prediction and control system in a narrow space. As the temperature of SMG is closely related to its drive mode frequency and driving voltage, a temperature prediction model can be established based on the BP neural network. The simulation results demonstrate that the established temperature prediction model can estimate the temperature in the range of ?40 to 60?C with an error of less than 0.05?C. Then, a temperature control system based on the combination of fuzzy logic controller and the increment PID control method is proposed. The simulation results prove that the Fuzzy-PID controller has a smaller steady state error, less rise time and better robustness than the PID controller. This is validated by experimental results that show the Fuzzy-PID control method can achieve high precision in keeping the SMG temperature stable at 55?C with an error of less than 0.2?C. The scale factor can be stabilized at 8.7?mV//s with a temperature coefficient of 33?ppm?C?1. ZRO (zero rate output) instability is decreased from 1.10/s (9.5?mV) to 0.08/s (0.7?mV) when the temperature control system is implemented over an ambient temperature range of ?40 to 60?C.

Xia, Dunzhu; Kong, Lun; Hu, Yiwei; Ni, Peizhen

2015-02-01

174

Precision Control of Thermal Transport in Cryogenic Single-Crystal Silicon Devices  

NASA Technical Reports Server (NTRS)

We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1 K. It is shown that the phonon mean-free-path is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than, even when the surface is fairly smooth, 510 nm rms, and the peak thermal wavelength is 0.6 microns. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of +/-8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

Rostem, K.; Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J.

2014-01-01

175

Precision control of thermal transport in cryogenic single-crystal silicon devices  

SciTech Connect

We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1?K. It is shown that the phonon mean-free-path ? is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than ?, even when the surface is fairly smooth, 510?nm rms, and the peak thermal wavelength is 0.6??m. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30?nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ?, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of 8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

Rostem, K., E-mail: karwan.rostem@nasa.gov [Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218 (United States); NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771 (United States); Chuss, D. T.; Colazo, F. A.; Crowe, E. J.; Denis, K. L.; Lourie, N. P.; Moseley, S. H.; Stevenson, T. R.; Wollack, E. J. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771 (United States)

2014-03-28

176

Silicon nanocrystals in SiNx/SiO2 hetero-superlattices: The loss of size control after thermal annealing  

NASA Astrophysics Data System (ADS)

Superlattices containing 3 nm thick silicon rich silicon nitride sublayers and 3 nm and 10 nm thick SiO2 barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3 nm SiO2 barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.5-12.5 nm, which were randomly distributed within the structure. Although in the sample with 10 nm SiO2 barriers some fragments of the multilayer structure could be still observed after thermal annealing, nevertheless, the formation of large nanocrystals with diameters up to 10 nm was confirmed by dark field transmission electron microscopy. Thus, in contrast to the previously published results, the expected size control of silicon nanocrystals was lost. According to the FTIR results, the thermal annealing of SiNx/SiO2 superlattices led to the formation of silicon nanocrystals in mostly oxynitride matrix. Annealed samples demonstrated a photoluminescence peak at 885 nm related to the luminescence of silicon nanocrystals, as confirmed by time-resolved photoluminescence measurements. The loss of nanocrystals size control is discussed in terms of the migration of oxygen atoms from the SiO2 barriers into the silicon rich silicon nitride sublayers. A thermodynamic mechanism responsible for this process is proposed. According to this mechanism, the driving force for the oxygen migration is the gain in the configuration entropy related to the relative arrangements of oxygen and nitrogen atoms.

Zelenina, A.; Sarikov, A.; Zhigunov, D. M.; Weiss, C.; Zakharov, N.; Werner, P.; Lpez-Conesa, L.; Estrad, S.; Peir, F.; Dyakov, S. A.; Zacharias, M.

2014-06-01

177

Improved performance alternator with fully integrated Switched-Mode Rectifier  

E-print Network

The use of Power Electronic circuits has helped to advance the technology of automotive alternators. The use of a Switched-Mode Rectifier (SMR) allows the alternator to run at a load-matched condition, optimizing power and ...

Mesa, Armando

2008-01-01

178

Performance Improvement of Alternators With Switched-Mode Rectifiers  

E-print Network

The use of a switched-mode rectifier (SMR) allows automotive alternators to operate at a load-matched condition at all operating speeds, overcoming the limitation of optimum performance at just one speed. While use of an ...

Rivas, Juan M.

179

99. POWER DISTRIBUTION UNITS FOR BATTERIES AND RECTIFIERS, NORTHEAST SIDE ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

99. POWER DISTRIBUTION UNITS FOR BATTERIES AND RECTIFIERS, NORTHEAST SIDE OF LANDLINE INSTRUMENTATION ROOM (106), LSB (BLDG. 770) - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

180

Rectifying effect through the interface of SrTiO3??/GaAs heterojunctions  

NASA Astrophysics Data System (ADS)

Oxides-semiconductor junctions have attracted great attention and exhibited promising potential in integrated devices in which the passing current is controlled by applying voltage. It is found that an oxygen-deficient SrTiO3??/p-GaAs junction displays an obvious rectifying effect. The SrTiO3?? thin film is in the anomalous in-plain compressive strain, as confirmed by structural characterization. Investigations on the currentvoltage curve show that the current decreases with the increasing temperature at the reverse bias, which suggests that the rectifying behavior may be attributed to the strain-assisted tunneling mechanism. The effect of strain or film thickness on the transport property is also discussed.

Zhai, Z. Y.; Xie, Q. Y.; Chen, G. B.; Yu, A. L.; Zhang, F. M.; Wu, X. S.

2014-11-01

181

Phosphoinositide regulation of inward rectifier potassium (Kir) channels  

PubMed Central

Inward rectifier potassium (Kir) channels are integral membrane proteins charged with a key role in establishing the resting membrane potential of excitable cells through selective control of the permeation of K+ ions across cell membranes. In conjunction with secondary anionic phospholipids, members of this family are directly regulated by phosphoinositides (PIPs) in the absence of other proteins or downstream signaling pathways. Different Kir isoforms display distinct specificities for the activating PIPs but all eukaryotic Kir channels are activated by PI(4,5)P2. On the other hand, the bacterial KirBac1.1 channel is inhibited by PIPs. Recent crystal structures of eukaryotic Kir channels in apo and lipid bound forms reveal one specific binding site per subunit, formed at the interface of N- and C-terminal domains, just beyond the transmembrane segments and clearly involving some of the key residues previously identified as controlling PI(4,5)P2 sensitivity. Computational, biochemical, and biophysical approaches have attempted to address the energetic determinants of PIP binding and selectivity among Kir channel isoforms, as well as the conformational changes that trigger channel gating. Here we review our current understanding of the molecular determinants of PIP regulation of Kir channel activity, including in context with other lipid modulators, and provide further discussion on the key questions that remain to be answered. PMID:24409153

Frst, Oliver; Mondou, Benoit; D'Avanzo, Nazzareno

2014-01-01

182

A method of rectifying current at microscales  

NASA Astrophysics Data System (ADS)

A method for rectifying electric current in micro and nanoscale devices is proposed based on the asymmetric concentration of polarization in an electrolyte solution in the case where the current in a microdiode successively passes through two mutually undissolvable fluids with different dielectric constants and diffusion coefficients in tubes with different dimensions. It is assumed that both fluids contain the ions of a completely dissociated substance which provide electric charge transfer upon application of a potential difference to the walls of the device, and the interface between the two fluids has a charge. The process is described by a one-dimensional nonstationary Nernst-Planck-Poisson system. The boundary conditions on the electrodes are the impermeability condition for anions and the Arrhenius equation which defines the flow of cations. The system of equations was solved numerically: the unknowns were decomposed into a complete system of orthogonal functions of the spatial variable, and the resulting dynamical system for the Galerkin coefficients was integrated over time by the Gear method because of its stiffness. The parameters of the system that have the most significant effect on the degree of rectification are determined, and their optimum values are evaluated.

Demekhin, E. A.; Baryshev, M. G.; Ganchenko, G. S.; Gorbacheva, E. V.

2014-09-01

183

Precision envelope detector and linear rectifier circuitry  

DOEpatents

Disclosed is a method and apparatus for the precise linear rectification and envelope detection of oscillatory signals. The signal is applied to a voltage-to-current converter which supplies current to a constant current sink. The connection between the converter and the sink is also applied through a diode and an output load resistor to a ground connection. The connection is also connected to ground through a second diode of opposite polarity from the diode in series with the load resistor. Very small amplitude voltage signals applied to the converter will cause a small change in the output current of the converter, and the difference between the output current and the constant current sink will be applied either directly to ground through the single diode, or across the output load resistor, dependent upon the polarity. Disclosed also is a full-wave rectifier utilizing constant current sinks and voltage-to-current converters. Additionally, disclosed is a combination of the voltage-to-current converters with differential integrated circuit preamplifiers to boost the initial signal amplitude, and with low pass filtering applied so as to obtain a video or signal envelope output.

Davis, Thomas J. (Richland, WA)

1980-01-01

184

Formation of composite polyacrylamide and silicone substrates for independent control of stiffness and strain  

PubMed Central

Cells that line major tissues in the body such as blood vessels, lungs and gastrointestinal tract experience deformation from mechanical strain with our heartbeat, breathing, and other daily activities. Tissues also remodel in both development and disease, changing their mechanical properties. Taken together, cells can experience vastly different mechanical cues resulting from the combination of these interdependent stimuli. To date, most studies of cellular mechanotransduction have been limited to assays in which variations in substrate stiffness and strain were not combined. Here, we address this technological gap by implementing a method that can simultaneously tune both substrate stiffness and mechanical strain. Substrate stiffness is controlled with different monomer and crosslinker ratios during polyacrylamide gel polymerization, and strain is transferred from the underlying silicone platform when stretched. We demonstrate this platform with polyacrylamide gels with elastic moduli at 6 kPa and 20 kPa in combination with two different silicone formulations. The gels remain attached with up to 50% applied strains. To validate strain transfer through the gels into cells, we employ particle-tracking methods and observe strain transmission via cell morphological changes. PMID:23287818

Simmons, Chelsey S.; Ribeiro, Alexandre J. S.; Pruitt, Beth L.

2013-01-01

185

Hydrogenated amorphous silicon deposited under accurately controlled ion bombardment using pulse-shaped substrate biasing  

SciTech Connect

We have applied pulse-shaped biasing to the expanding thermal plasma deposition of hydrogenated amorphous silicon at substrate temperatures {approx}200 deg. C and growth rates around 1 nm/s. Substrate voltage measurements and measurements with a retarding field energy analyzer demonstrate the achieved control over the ion energy distribution for deposition on conductive substrates and for deposition of conductive materials on nonconductive substrates. Presence of negative ions/particles in the Ar-H{sub 2}-SiH{sub 4} plasma is deduced from a voltage offset during biasing. Densification of the material at low Urbach energies is observed at a deposited energy <4.8 eV/Si atom and attributed to an increase in surface mobility of mobile species as well as well as surface atom displacement. The subsequent increase in Urbach energy >4.8 eV/Si atom is attributed to bulk atom displacement in subsurface layers. We make the unique experimental abservation of a decreasing Tauc band gap at increasing total hydrogen concentration - this allows to directly relate the band gap of amorphous silicon to the presence of nanovoids in the material.

Wank, M. A.; Swaaij, R. A. C. M. M. van; Zeman, M. [Photovoltaic Materials and Devices Group/DIMES, Delft University of Technology, P.O. Box 5053, Delft 2600 GB (Netherlands); Kudlacek, P.; Sanden, M. C. M. van de [Department of Applied Physics, Plasma and Material Processing Group, Eindhoven University of Technology, Eindhoven 5600 MB (Netherlands)

2010-11-15

186

Electrical control of interfacial trapping for magnetic tunnel transistor on silicon  

NASA Astrophysics Data System (ADS)

We demonstrate an electrical control of an interfacial trapping effect for hot electrons injected in silicon by studying a magnetic tunnel transistor on wafer bonded Si substrate. Below 25 K, hot electrons are trapped at the Cu/Si interface, resulting in collector current suppression through scattering in both parallel and antiparallel magnetic configurations. Consequently, the magneto-current ratio strongly decreases from 300% at 27 K to 30% at 22 K. The application of a relatively small electric field (333 V/cm) across the Cu/Si interface is enough to strip the trapped electrons and restore the magneto-current ratio at low temperature. We also present a model taking into account the effects of both electric field and temperature that closely reproduces the experimental results and allows extraction of the trapping binding energy (1.6 meV).

Lu, Y.; Lacour, D.; Lengaigne, G.; Le Gall, S.; Suire, S.; Montaigne, F.; Hehn, M.; Wu, M. W.

2014-01-01

187

Stress as a governing parameter to control the crystallization of amorphous silicon films by thermal annealing  

NASA Astrophysics Data System (ADS)

We have fabricated nanocrystalline dots by thermal annealing (TA) of thermal chemical-vapor-deposited amorphous silicon (a-Si:H) films. In S. Hazra, I. Sakata, M. Yamanaka, and E. Suzuki, Appl. Phys. Lett. 80, 1159 (2002), we observed that ultrathin a-Si:H films (2-10 nm) are stressed because of the presence of deformed crystallites or paracrystallites. With the increase of thickness, volume fraction of paracrystallites decreased in the films and stress in the films gradually reduced. Therefore, by changing the thickness, we can control the stress in the a-Si:H films and thereby the dimensions (in the range of 5 to 10 nm) as well as volume fractions of nanocrystallites formed by TA. On the other hand, it has been found that relaxed a-Si:H networks form polycrystalline films by TA.

Hazra, Sukti; Sakata, Isao; Yamanaka, Mitsuyuki; Suzuki, Eiichi

2002-06-01

188

Controlled growth of monolayer graphene on silicon carbide in argon atmosphere  

NASA Astrophysics Data System (ADS)

Controlled thermal decomposition of silicon carbide is so far the most effective method for growing graphene epitaxially and at the wafer scale. In this work we study the graphenization of SiC(0001) and SiC(0001) as a function of ambient argon pressure and temperature in a custom-built ultrahigh vacuum (UHV) induction furnace. In-situ characterization by both Auger electron spectroscopy and low-energy electron diffraction (LEED) was used to determine the pressure-temperature ``phase boundary'' for the formation of monolayer graphene. Sample quality was further assessed ex-situ using a variety of techniques such Raman spectroscopy and scanning tunneling microscopy. The effect of the inert argon overpressure was modeled numerically with a simple kinetic growth theory.

Torrance, David; Miller, David; Tinkey, Holly; Green, Evan; Phillips, Madeleine; First, Phillip

2009-11-01

189

Doping strategies to control A-centres in silicon: insights from hybrid density functional theory.  

PubMed

Hybrid density functional theory is used to gain insights into the interaction of intrinsic vacancies (V) and oxygen-vacancy pairs (VO, known as A-centres) with the dopants (D) germanium (Ge), tin (Sn), and lead (Pb) in silicon (Si). We determine the structures as well as binding and formation energies of the DVO and DV complexes. The results are discussed in terms of the density of states and in view of the potential of isovalent doping to control A-centres in Si. We argue that doping with Sn is the most efficient isovalent doping strategy to suppress A-centres by the formation of SnVO complexes, as these are charge neutral and strongly bound. PMID:24667874

Wang, H; Chroneos, A; Londos, C A; Sgourou, E N; Schwingenschlgl, U

2014-05-14

190

Temperature-Controlled Growth of Silicon-Based Nanostructures by Thermal Evaporation of SiO Powders  

E-print Network

-10 laser ablation of metal- containing Si target11-14 or metal-free Si/SiO2 target,11,15 and thermal-10 and laser ablation.11-15 In thermal evaporation, oxides were found to play a dominant role in the nucleationTemperature-Controlled Growth of Silicon-Based Nanostructures by Thermal Evaporation of SiO Powders

Wang, Zhong L.

191

Rectifying thermal fluctuations: Minimal pumping and Maxwell's demon  

NASA Astrophysics Data System (ADS)

Molecular complexes with movable components form the basis of nanoscale machines. Their inherent stochastic nature makes it a challenge to generate any controllable movement. Rather than fighting these fluctuations, one can utilize them by the periodic modulation of system parameters, or stochastic pumping. For the no-pumping theorem (NPT), which establishes minimal conditions for directed pumping, we present a simplified proof using an elementary graph theoretical construction. Motivated by recent experiments, we propose a new class of "hybrid" models combining elements of both the purely discrete and purely continuous descriptions prevalent in the field. We formulate the NPT in this hybrid framework to give a detailed justification of the original experiment observation. We also present an extension of the NPT to open stochastic systems. Next we consider the paradox of "Maxwell's demon," an imaginary intelligent being that rectifies thermal fluctuations in a manner that seems to violate the second law of thermodynamics. We present two exactly solvable, autonomous models that can reproduce the actions of the demon. Of necessity, both of these models write information on a memory device as part of their operation. By exposing their explicit, transparent mechanisms, our models offer simple paradigms to investigate the autonomous rectification of thermal fluctuations and the thermodynamics of information processing.

Mandal, Dibyendu

192

Room temperature coherent control of defect spin qubits in silicon carbide.  

PubMed

Electronic spins in semiconductors have been used extensively to explore the limits of external control over quantum mechanical phenomena. A long-standing goal of this research has been to identify or develop robust quantum systems that can be easily manipulated, for future use in advanced information and communication technologies. Recently, a point defect in diamond known as the nitrogen-vacancy centre has attracted a great deal of interest because it possesses an atomic-scale electronic spin state that can be used as an individually addressable, solid-state quantum bit (qubit), even at room temperature. These exceptional quantum properties have motivated efforts to identify similar defects in other semiconductors, as they may offer an expanded range of functionality not available to the diamond nitrogen-vacancy centre. Notably, several defects in silicon carbide (SiC) have been suggested as good candidates for exploration, owing to a combination of computational predictions and magnetic resonance data. Here we demonstrate that several defect spin states in the 4H polytype of SiC (4H-SiC) can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin. Using optical and microwave techniques similar to those used with diamond nitrogen-vacancy qubits, we study the spin-1 ground state of each of four inequivalent forms of the neutral carbon-silicon divacancy, as well as a pair of defect spin states of unidentified origin. These defects are optically active near telecommunication wavelengths, and are found in a host material for which there already exist industrial-scale crystal growth and advanced microfabrication techniques. In addition, they possess desirable spin coherence properties that are comparable to those of the diamond nitrogen-vacancy centre. This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical electronic and optical technologies. PMID:22051676

Koehl, William F; Buckley, Bob B; Heremans, F Joseph; Calusine, Greg; Awschalom, David D

2011-11-01

193

High-fidelity readout and control of a nuclear spin qubit in silicon.  

PubMed

Detection of nuclear spin precession is critical for a wide range of scientific techniques that have applications in diverse fields including analytical chemistry, materials science, medicine and biology. Fundamentally, it is possible because of the extreme isolation of nuclear spins from their environment. This isolation also makes single nuclear spins desirable for quantum-information processing, as shown by pioneering studies on nitrogen-vacancy centres in diamond. The nuclear spin of a (31)P donor in silicon is very promising as a quantum bit: bulk measurements indicate that it has excellent coherence times and silicon is the dominant material in the microelectronics industry. Here we demonstrate electrical detection and coherent manipulation of a single (31)P nuclear spin qubit with sufficiently high fidelities for fault-tolerant quantum computing. By integrating single-shot readout of the electron spin with on-chip electron spin resonance, we demonstrate quantum non-demolition and electrical single-shot readout of the nuclear spin with a readout fidelity higher than 99.8 percent-the highest so far reported for any solid-state qubit. The single nuclear spin is then operated as a qubit by applying coherent radio-frequency pulses. For an ionized (31)P donor, we find a nuclear spin coherence time of 60 milliseconds and a one-qubit gate control fidelity exceeding 98 percent. These results demonstrate that the dominant technology of modern electronics can be adapted to host a complete electrical measurement and control platform for nuclear-spin-based quantum-information processing. PMID:23598342

Pla, Jarryd J; Tan, Kuan Y; Dehollain, Juan P; Lim, Wee H; Morton, John J L; Zwanenburg, Floris A; Jamieson, David N; Dzurak, Andrew S; Morello, Andrea

2013-04-18

194

Morphology-controlled synthesis of poly(oxyethylene)silicone or alkylsilicone surfactants with explicit, atomically defined, branched, hydrophobic tails.  

PubMed

Silicone surfactants are widely used in commerce because of the unusual surface activity when compared with fluorocarbon or hydrocarbon surfactants. However, most silicone surfactants are comprised of ill-defined mixtures, which preclude the development of an understanding of structure-surface activity relationships. Herein, we report a synthetic strategy that permits exquisite control over silicone structure by using the B(C(6)F(5))(3)-catalyzed condensation of hydro- and alkoxysilanes. Six different, precise hydrophobes were then mated to hydrophilic poly(oxyethylene)s of three different molecular weights by a metal-free click cyclization to generate a library of explicit silicone surfactants. These compounds were calculated to have a relatively linear value range of the hydrophilic-lipophilic balance, ranging from about 8 to about 15. The solubility of some of the compounds was too low to measure a critical micelle concentration (CMC). The others exhibited a broad range of surface tension values at the CMC that depend both on the length of the hydrophilic tail and, more importantly, the nature of the hydrophobic head group. Subtle distinctions in surfactant-related properties, which can be attributed to the three-dimensional structures, can be seen for compounds with comparable numbers of hydrocarbons and silicon groups. PMID:22213091

Gonzaga, Ferdinand; Grande, John B; Brook, Michael A

2012-01-27

195

Numerically controlled atmospheric-pressure plasma sacrificial oxidation using electrode arrays for improving silicon-on-insulator layer uniformity  

NASA Astrophysics Data System (ADS)

Silicon-on-insulator (SOI) wafers are important semiconductor substrates in high-performance devices. In accordance with device miniaturization requirements, ultrathin and highly uniform top silicon layers (SOI layers) are required. A novel method involving numerically controlled (NC) atmospheric-pressure plasma sacrificial oxidation using an electrode array system was developed for the effective fabrication of an ultrathin SOI layer with extremely high uniformity. Spatial resolution and oxidation properties are the key factors controlling ultraprecision machining. The controllability of plasma oxidation and the oxidation properties of the resulting experimental electrode array system were examined. The results demonstrated that the method improved the thickness uniformity of the SOI layer over one-sixth of the area of an 8-in. wafer area.

Takei, Hiroyasu; Yoshinaga, Keinosuke; Matsuyama, Satoshi; Yamauchi, Kazuto; Sano, Yasuhisa

2015-01-01

196

High-fidelity readout and control of a nuclear spin qubit in silicon  

E-print Network

A single nuclear spin holds the promise of being a long-lived quantum bit or quantum memory, with the high fidelities required for fault-tolerant quantum computing. We show here that such promise could be fulfilled by a single phosphorus (31P) nuclear spin in a silicon nanostructure. By integrating single-shot readout of the electron spin with on-chip electron spin resonance, we demonstrate the quantum non-demolition, electrical single-shot readout of the nuclear spin, with readout fidelity better than 99.8% - the highest for any solid-state qubit. The single nuclear spin is then operated as a qubit by applying coherent radiofrequency (RF) pulses. For an ionized 31P donor we find a nuclear spin coherence time of 60 ms and a 1-qubit gate control fidelity exceeding 98%. These results demonstrate that the dominant technology of modern electronics can be adapted to host a complete electrical measurement and control platform for nuclear spin-based quantum information processing.

Jarryd J. Pla; Kuan Y. Tan; Juan P. Dehollain; Wee H. Lim; John J. L. Morton; Floris A. Zwanenburg; David N. Jamieson; Andrew S. Dzurak; Andrea Morello

2013-02-01

197

Vertically aligned crystalline silicon nanowires with controlled diameters for energy conversion applications: Experimental and theoretical insights  

SciTech Connect

Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters are fabricated via a metal-assisted chemical etching method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H{sub 2}O{sub 2} electrolytes. The fabricated SiNWs have diameters ranging from 117 to 650?nm and lengths from 8 to 18??m. The optical measurements showed a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670?nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ?670?nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ?660?nm. The x-ray diffraction patterns confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse band toward lower frequencies compared to that usually seen for c-Si. Finite difference time domain simulations have been performed to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results showed good agreement with the experimental results for the SiNWs of different diameters.

Razek, Sara Abdel; Swillam, Mohamed A.; Allam, Nageh K., E-mail: nageh.allam@aucegypt.edu [Department of Physics, School of Sciences and Engineering, The American University in Cairo, New Cairo 11835 (Egypt)

2014-05-21

198

Non-equilibrium 1/f noise in rectifying nanopores  

SciTech Connect

We report a single rectifying conically shaped nanopore system with ion current fluctuations whose 1/f noise characteristics observed at low frequencies are voltage dependent. Switching the voltage polarity allows one to switch between a system that produces equilibrium and nonequilibrium 1/f ion current fluctuations. The nonequilibrium fluctuations in the high-conductance state of the device are characterized by exponential dependence of the normalized power spectrum on voltage. The asymmetric 1/f noise is found characteristic for rectifying polymer nanopores and absent in pores with Ohmic current-voltage curves.

Vlassiouk, Ivan V [ORNL

2009-01-01

199

Parameter Plane Synthesis and Performance Investigation of a Three-Phase Three-Level Bidirectional Rectifier  

NASA Astrophysics Data System (ADS)

In this paper, parameter plane synthesis of a three-phase neutral-point clamped bidirectional rectifier has been performed. The converter involves one outer-loop PI voltage controller and two inner-loop PI current controllers for the closed-loop control. D-partition technique has been employed for the precise design of the voltage controller. An experimental prototype of the converter has been developed, and the experimental investigation of the converter performance in closed loop has been carried out. DSP DS1104 of dSPACE has been used for real-time implementation of the designed controller. The converter gives a very good performance in steady state and dynamic state (for rectification as well as inversion modes of operation) using the designed controller parameters.

Bhat, Abdul Hamid; Langer, Nitin

2014-12-01

200

Controllable Change of Photoluminescence Spectra of Silicone Rubber Modified by 193 nm ArF Excimer Laser  

NASA Astrophysics Data System (ADS)

Photoluminescence spectra of silicone rubber ([SiO(CH3)2]n) photochemically modified by a 193 nm ArF excimer laser was found to be controllable. Compared with the modification in air, the photoluminescence spectra could be blueshifted by the modification in vacuum or the additional irradiation of ArF excimer laser in vacuum after the modification in air. To redshift, on the other hand, the additional irradiation of a 157 nm F2 laser in air after the modification in air, the modification in oxygen gas, or the postannealing after the modification in oxygen gas was effective. The blue and redshifts of the photoluminescence were essentially due to the acceleration of reduction and oxidation reactions of silicone rubber, respectively, because the photoluminescence derives its origin from oxygen deficiency centers and peroxy centers of the silica structure in the modified silicone rubber. On the basis of the spectra changes, colorful light-guiding sheets made of silicone rubber under illumination of a 375 nm light-emitting diode were successfully fabricated for cellular phone use.

Okoshi, Masayuki; Iyono, Minako; Inoue, Narumi

2009-12-01

201

125. JOB NO. LINE 5044, INTERNATIONAL RECTIFIER CORP., RACHELLE LABORATORIES, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

125. JOB NO. LINE 5044, INTERNATIONAL RECTIFIER CORP., RACHELLE LABORATORIES, INC., LONG BEACH, CA, BY J.C. FULTON, SEPTEMBER 1982, LINE 5044, CLIFTON AND CO., ON FILE ENGINEERS DEPARTMENT, PORT OF LONG BEACH - Ford Motor Company Long Beach Assembly Plant, Assembly Building, 700 Henry Ford Avenue, Long Beach, Los Angeles County, CA

202

Efficiency of Frequency-Rectified Piezohydraulic and Piezopneumatic Actuation  

Microsoft Academic Search

Piezohydraulic and piezopneumatic frequency rectification is analyzed with a steady-state model of work and energy transfer. In this paper, piezohydraulic actuation is defined as the use of incompressible fluid to rectify the oscillatory motion of a piezoelectric device into unidirectional motion; piezopneumatic actuation is the use of a compressible gas such as air. The steady-state analysis is based on the

Khalil Nasser; Donald J. Leo

2000-01-01

203

RECTIFIERS AND THE LOCAL LANGLANDS CORRESPONDENCE: THE UNRAMIFIED CASE  

E-print Network

RECTIFIERS AND THE LOCAL LANGLANDS CORRESPONDENCE: THE UNRAMIFIED CASE MOSHE ADRIAN AND DAVID ROEL/K(L?). The twist giving the 1 #12;2 MOSHE ADRIAN AND DAVID ROE correct supercuspidal representation of PGL2(K tori T in connected reductive groups G. Benedict Gross' recent construction of groups of type L

Roe, David

204

Rectifier transformers in electric traction substations ? different designs  

Microsoft Academic Search

Electric traction in Poland is supplied with dc voltage which is obtained from the power grid via traction substations equipped with transformers and rectifiers. The paper gives the results of the investigation of different designs of these transformer?rectfier sets ? namely, 12? and 24?pulse systems. The comparison of electrical quantities such as ripple content, harmonic content of supply current and

Barbara Kulesz

2005-01-01

205

1MHz High Efficiency LLC Resonant Converters with Synchronous Rectifier  

Microsoft Academic Search

This paper proposes a novel synchronous rectifier driving scheme for resonant converters. An LLC resonant converter with proposed synchronous rectification is designed and analyzed. It is a high efficiency, high power density solution for future frond end converters. Hold up time extension capability is achieved for designed LLC resonant converter without sacrificing the efficiency for nominal condition. 1kW, 1MHz LLC

Dianbo Fu; Bing Lu; Fred C. Lee

2007-01-01

206

A Vertical Diffusion Scheme to estimate the atmospheric rectifier effect  

Microsoft Academic Search

The magnitude and spatial distribution of the carbon sink in the extratropical Northern Hemisphere remain uncertain in spite of much progress made in recent decades. Vertical CO2 diffusion in the planetary boundary layer (PBL) is an integral part of atmospheric CO2 transport and is important in understanding the global CO2 distribution pattern, in particular, the rectifier effect on the distribution

Baozhang Chen; Jing M. Chen; Jane Liu; Douglas Chan; Kaz Higuchi; Alexander Shashkov

2004-01-01

207

37. VIEW OF SIX GAP ROTARY RECTIFIER FOR MAINTAINING CORONA ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

37. VIEW OF SIX GAP ROTARY RECTIFIER FOR MAINTAINING CORONA DISCHARGE IN THE COTTRELL ELECTROSTATIC GENERATORS. THE SYSTEM WAS CAPABLE OF PROVIDING 88,000 VOLTS TO THE ELECTRODES WITHIN THE PRECIPITATOR CHAMBER THE UNIT WAS LOCATED TO THE REAR OF BOILER 904 IN AN ENCLOSED ROOM. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

208

Seismic triggering by rectified diffusion in geothermal systems  

Microsoft Academic Search

Widespread seismicity was triggered by the June 28, 1992, Landers California, earthquake at a rate which was maximum immediately after passage of the exciting seismic waves. Rectified diffusion of vapor from hydrothermal liquids and magma into bubbles oscillating in an earthquake can increase the local pore pressure to seismically significant levels within the duration of the earthquake. In a hydrothermal

Bradford Sturtevant; Hiroo Kanamori; Emily E. Brodsky

1996-01-01

209

PWM rectifier in power cell of cascaded H-bridge multilevel converter  

Microsoft Academic Search

This paper proposes to use PWM rectifier to replace the diode rectifier in the cascaded H-bridge multilevel converter in order to regenerate the power from the load to the grid. The rectifier in this paper employs the leakage reactance of the secondary windings of the input transformer instead of physical reactor because of the large number of the reactors needed

Jian Wang; Yongdong Li

2007-01-01

210

Application of ant colony optimization-SVM in fault diagnosis for rectifier circuit  

Microsoft Academic Search

Failure of rectifier circuit has the characteristics of latency and complexity, which leads to the difficulty to fault diagnosis for rectifier circuit. A new method of optimizing support vector machine (SVM) by using ant colony optimization algorithm is presented to fault diagnosis for rectifier circuit in the paper. The experimental object is provided and the six ACO-SVM classifiers are developed

Xu Binghui

2010-01-01

211

All-optical single resonance control using a silicon-based ring-assisted Mach-Zehnder interferometer  

NASA Astrophysics Data System (ADS)

CMOS-compatible ring-based active devices have attracted significant attention for their ability to confine and manipulate light on a compact SOI platform. Active modulation of a ring resonator is typically achieved by changing the intensity response. As an alternative to intensity modulation, the phase modulation of the ring resonator can be converted into intensity modulation of a Mach-Zehnder interferometer (MZI) by means of a ring-assisted Mach-Zehnder interferometer (RAMZI) structure. We theoretically demonstrate an all-optical single resonance switching using a silicon RAMZI by optically controlling the intracavity loss of the side-coupled silicon ring based on inverse Raman scattering (IRS). The RAMZI structure improves the modulation robustness against fabrication deviations by relaxing the coupling condition for the ring resonator, without compensating the modulation performance. In silicon, the IRS produces optical loss with a bandwidth of 105 GHz at the anti-Stokes wavelength, which blueshifts 15.6 THz from the control light. For our proposed RAMZI structure, the IRS induced loss is spectrally wider than the linewidth of the side-coupled ring, but narrower than the free spectral range (FSR) of the ring, guaranteeing single resonance selectivity. When the control light pulse of 200 ps switches from "off" (zero) to "on" (20pJ), the transmission of the anti-Stokes resonance transfers from 1.7% to 92.3%. The proposed structure provides the potential to multichannel all-optical routers on a CMOS compatible platform.

Xiong, Yule; Ye, Winnie N.

2013-02-01

212

Finite Element Analysis of Silicone Rubber Spacers Used in Automotive Engine Control Modules  

Microsoft Academic Search

Silicone Rubber Spacers in the shape of truncated cones are used in automotive electronic applications to ensure thermal or electrical contact between different components. In one such application, the \\

Fereydoon Dadkhah; Arlene Zahiri

213

Method of purifying metallurgical grade silicon employing reduced pressure atmospheric control  

NASA Technical Reports Server (NTRS)

A method in which a quartz tube is charged with chunks of metallurgical grade silicon and/or a mixture of such chunks and high purity quartz sand, and impurities from a class including aluminum, boron, as well as certain transition metals including nickel, iron, and manganese is described. The tube is then evacuated and heated to a temperature within a range of 800 C to 1400 C. A stream of gas comprising a reactant, such as silicon tetrafluoride, is continuously delivered at low pressures through the charge for causing a metathetical reaction of impurities of the silicon and the reactant to occur for forming a volatile halide and leaving a residue of silicon of an improved purity. The reactant which included carbon monoxide gas and impurities such as iron and nickel react to form volatile carbonyls.

Ingle, W. M.; Thompson, S. W.; Chaney, R. E. (inventors)

1979-01-01

214

Control of silicon solidification and the impurities from an Al-Si melt  

NASA Astrophysics Data System (ADS)

The investigation on purification of metallurgical grade silicon by solidification of hypereutectic Al-Si melt under the temperature gradient as an intensified separation way was carried out. Based on the available thermodynamic parameters and experimental data, the thermodynamic behavior and chemical composition of metallic impurities was studied in the solidification process. The principle for the silicon growth in the Al-Si melts was investigated. The results indicated that the refined silicon grains were successfully enriched at the top of the Al-Si alloy. Then the top part refined silicon was collected by aqua regia leaching. Electrorefining of the bottom part (Al-22%Si) was investigated effectively in view of recovering pure Si and Al. Additionally, according to previous investigation, the optimized technical process for SOG-Si production was proposed.

Wang, Panpan; Lu, Huimin; Lai, Yuanshi

2014-03-01

215

SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications  

SciTech Connect

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.

Onar, Omer C [ORNL] [ORNL; Tang, Lixin [ORNL] [ORNL; Chinthavali, Madhu Sudhan [ORNL] [ORNL; Campbell, Steven L [ORNL] [ORNL; Miller (JNJ), John M. [JNJ-Miller PLC] [JNJ-Miller PLC

2014-01-01

216

Functional Nanoscale Electronic Devices Assembled Using Silicon Nanowire Building Blocks  

Microsoft Academic Search

Because semiconductor nanowires can transport electrons and holes, they could function as building blocks for nanoscale electronics assembled without the need for complex and costly fabrication facilities. Boron- and phosphorous-doped silicon nanowires were used as building blocks to assemble three types of semiconductor nanodevices. Passive diode structures consisting of crossed p- and n-type nanowires exhibit rectifying transport similar to planar

Yi Cui; Charles M. Lieber

2001-01-01

217

Interface-reaction controlled diffusion in binary solids with applications to lithiation of silicon in lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Solid state diffusion in a binary system, such as lithiation into crystalline silicon, often involves two symbiotic processes, namely, interfacial chemical reaction and bulk diffusion. Building upon our earlier work (Cui et al., 2012b, J. Mech. Phys. Solids, 60 (7), 1280-1295), we develop a mathematical framework in this study to investigate the interaction between bulk diffusion and interfacial chemical reaction in binary systems. The new model accounts for finite deformation kinematics and stress-diffusion interaction. It is applicable to arbitrary shape of the phase interface. As an example, the model is used to study the lithiation of a spherical silicon particle. It is found that a dimensionless parameter ?=kfeVmBR0/D0 plays a significant role in determining the kinetics of the lithiation process. This parameter, analogous to the Biot number in heat transfer, represents the ratio of the rate of interfacial chemical reaction and the rate of bulk diffusion. Smaller ? means slower interfacial reaction, which would result in higher and more uniform concentration of lithium in the lithiated region. Furthermore, for a given ?, the lithiation process is always controlled by the interfacial chemical reaction initially, until sufficient silicon has been lithiated so that the diffusion distance for lithium reaches a threshold value, beyond which bulk diffusion becomes the slower process and controls the overall lithiation kinetics.

Cui, Zhiwei; Gao, Feng; Qu, Jianmin

2013-02-01

218

Process for the controlled growth of single-crystal films of silicon carbide polytypes on silicon carbide wafers  

NASA Technical Reports Server (NTRS)

A method for the controlled growth of single-crystal semiconductor-device-quality films of SiC polytypes on vicinal (0001) SiC wafers with low tilt angles is presented. Both homoepitaxial and heteroepitaxial SiC films can be produced on the same wafer. In particular, 3C-SiC and 6H-SiC films can be produced within selected areas of the same 6H-SiC wafer.

Larkin, David J. (inventor); Powell, J. Anthony (inventor)

1992-01-01

219

Process for the controlled growth of single-crystal films of silicon carbide polytypes on silicon carbide wafers  

NASA Technical Reports Server (NTRS)

This invention is a method for the controlled growth of single-crystal semiconductor device quality films of SiC polytypes on vicinal (0001) SiC wafers with low tilt angles. Both homoepitaxial and heteroepitaxial SiC films can be produced on the same wafer. In particular, 3C-SiC and 6H-SiC films can be produced within selected areas of the same 6H-SiC wafer.

Powell, J. Anthony (inventor)

1991-01-01

220

Improving the stability of nanostructured silicon thin film lithium-ion battery anodes through their controlled oxidation.  

PubMed

Silicon and partially oxidized silicon thin films with nanocolumnar morphology were synthesized by evaporative deposition at a glancing angle, and their performance as lithium-ion battery anodes was evaluated. The incorporated oxygen concentration was controlled by varying the partial pressure of water during the deposition and monitored by quartz crystal microbalance, X-ray photoelectron spectroscopy. In addition to bulk oxygen content, surface oxidation and annealing at low temperature affected the cycling stability and lithium-storage capacity of the films. By simultaneously optimizing all three, films of ~2200 mAh/g capacity were synthesized. Coin cells made with the optimized films were reversibly cycled for ~120 cycles with virtually no capacity fade. After 300 cycles, 80% of the initial reversible capacity was retained. PMID:22372404

Abel, Paul R; Lin, Yong-Mao; Celio, Hugo; Heller, Adam; Mullins, C Buddie

2012-03-27

221

The effect of silica nucleation layers on grain control of multi-crystalline silicon in directional solidification  

NASA Astrophysics Data System (ADS)

The grain control in multi-crystalline silicon growth by directional solidification is crucial to the ingot quality. In order to study the nucleation and grain growth behavior, we carried out ingot growth using porous silica coatings, with different Si/SiO2 ratios, and the traditional nitride coating for comparison, at the bottom of a small crucible. It was observed that with more silica in the coating, smaller and uniform grains, as well as columnar growth, could be obtained. As a result, more non-? grain boundaries were found as well. On the contrary, as silicon became a continuous phase in the coating, the grain refinement was less effective and their grain development in the porous coating was examined. The possible grain nucleation and growth mechanisms in the porous coatings were further proposed.

Wong, Y. T.; Hsieh, C. T.; Lan, A.; Hsu, C.; Lan, C. W.

2014-10-01

222

Improved size distribution control of silicon nanocrystals in a spatially confined remote plasma  

NASA Astrophysics Data System (ADS)

This work demonstrates how to improve the size distribution of silicon nanocrystals (Si-NCs) synthesized in a remote plasma, in which the flow dynamics and the particular chemistry initially resulted in the formation of small (210 nm) and large (50120 nm) Si-NCs. Plasma consists of two regions: an axially expanding central plasma beam and a background region around the expansion. Continuum fluid dynamics simulations demonstrate that a significant mass flow occurs from the central beam to the background region. This mass flow can be gradually reduced upon confinement of the central beam, preventing the mass transport to the background region. Transmission electron microscopy and Raman spectroscopy analyses demonstrate that the volume fraction of large Si-NCs decreases from ?77% to below 45% in parallel with the decrease of mass flow to the background region upon confinement, which indicates that large Si-NCs are synthesized in the background and small Si-NCs are synthesized in the central beam. Spatially resolved ion flux analyses demonstrate that the ions are localized in the central beam despite the mass flow to the background, indicating that the formation of small Si-NCs is governed by ion-assisted growth while the formation of large Si-NCs is governed by radical-neutral-assisted growth in the absence of ions. According to these observations, a better uniformity in the size distribution of Si-NCs can be obtained by creating a more uniform plasma flow and controlling the density of plasma species in the plasma.

Do?an, ?lker; Westerman, Ren H. J.; van de Sanden, Mauritius C. M.

2015-02-01

223

Optically-controlled extinction ratio and Q-factor tunable silicon microring resonators based on optical forces  

NASA Astrophysics Data System (ADS)

Tunability is a desirable property of microring resonators to facilitate superior performance. Using light to control light, we present an alternative simple approach to tuning the extinction ratio (ER) and Q-factor of silicon microring resonators based on optical forces. We design an opto-mechanical tunable silicon microring resonator consisting of an add-drop microring resonator and a control-light-carrying waveguide (``controlling'' waveguide). One of the two bus waveguides of the microring resonator is a deformable nanostring put in parallel with the ``controlling'' waveguide. The tuning mechanism relies on the optical force induced deflection of suspended nanostring, leading to the change of coupling coefficient of microring and resultant tuning of ER and Q-factor. Two possible geometries, i.e. double-clamped nanostring and cantilever nanostring, are studied in detail for comparison. The obtained results imply a favorable structure with the microring positioned at the end of the cantilever nanostring. It features a wide tuning range of ER from 5.6 to 39.9 dB and Q-factor from 309 to 639 as changing the control power from 0 to 1.4 mW.

Long, Yun; Wang, Jian

2014-06-01

224

Development of a Thermal Rectifier Usable at High Temperature  

NASA Astrophysics Data System (ADS)

By using Al-based metallic alloys characterized by a disordered structure and a narrow pseudogap of a few hundred meV in energy width persisting at the Fermi level, we succeeded in preparing materials possessing a large increase of thermal conductivity with increasing temperature. This unusual increase of thermal conductivity is caused by the electronic structure effect known as the bipolar diffusion effect (BDE) in the context of the two-band model. A thermal rectifier was constructed using materials exhibiting the BDE. By showing the thermal rectification of the bulk sample prepared in this study, we demonstrate that our newly proposed idea of a thermal rectifier using the BDE is applicable for practical use.

Takeuchi, Tsunehiro; Goto, Hiroki; Toyama, Yasuhiro; Itoh, Takashi; Mikami, Masashi

2011-05-01

225

Exploiting silicon chip technology for control of electrons on superfluid helium.  

SciTech Connect

Electrons on the surface of superfluid helium have extremely high mobilities and long predicted spin coherence times, making them ideal mobile qubits. Previous work has shown that electrons localized in helium filled channels can be reliably transported between multiple underlying gates. Silicon chips have been designed, fabricated, and post processed by reactive ion etching to leverage the large scale integration capabilities of silicon technology. These chips, which serve as substrates for the electrons on helium research, utilize silicon CMOS for on-chip signal amplification and multiplexing and the uppermost metal layers for defining the helium channels and applying electrical potentials for moving the electrons. We will discuss experimental results for on-chip circuitry and clocked electron transport along etched channels.

Gurrieri, Thomas M.; Lyon, Stephen A. (Princeton University); Wilkel, Kathy J.; Eng, Kevin; Bradbury, Forrest (Princeton University); Takita, Maika (Princeton University)

2010-03-01

226

Ultrafast optical control using the Kerr nonlinearity in hydrogenated amorphous silicon microcylindrical resonators  

PubMed Central

Microresonators are ideal systems for probing nonlinear phenomena at low thresholds due to their small mode volumes and high quality (Q) factors. As such, they have found use both for fundamental studies of light-matter interactions as well as for applications in areas ranging from telecommunications to medicine. In particular, semiconductor-based resonators with large Kerr nonlinearities have great potential for high speed, low power all-optical processing. Here we present experiments to characterize the size of the Kerr induced resonance wavelength shifting in a hydrogenated amorphous silicon resonator and demonstrate its potential for ultrafast all-optical modulation and switching. Large wavelength shifts are observed for low pump powers due to the high nonlinearity of the amorphous silicon material and the strong mode confinement in the microcylindrical resonator. The threshold energy for switching is less than a picojoule, representing a significant step towards advantageous low power silicon-based photonic technologies. PMID:24097126

Vukovic, N.; Healy, N.; Suhailin, F. H.; Mehta, P.; Day, T. D.; Badding, J. V.; Peacock, A. C.

2013-01-01

227

Stress control of piezoelectric ZnO films on silicon substrates  

NASA Astrophysics Data System (ADS)

Piezoelectric zinc oxide (ZnO) films are widely used for the generation and detection of acoustic waves in non-piezoelectric substrates. The application of these films on silicon offers the possibility of realizing acoustic wave devices integrated with electronic circuits, e.g. sensors. It has been demonstrated that ZnO films can be combined with standard bipolar or CMOS IC processes. However, the stress in ZnO is still an important drawback and hinders the further development of silicon integrated acoustic wave devices, particularly if the ZnO layer is deposited on thin membranes, e.g. Lamb wave devices. In this paper we discuss aspects of stress in ZnO, methods to prevent or reduce the stress and we describe an IC-compatible method for the determination of the stress in ZnO films deposited on 100 mm diameter silicon wafers.

Cimpoiasu, A.; van der Pers, N. M.; de Keyser, Th H.; Venema, A.; Vellekoop, M. J.

1996-12-01

228

Voltage Sequence Control Based High-Current Rectifier System  

E-print Network

to be a fairly matured technology, its use in industry is limited as compared to passive filters [6-8]. Passive of transformer. A passive filter is added at the primary side to achieve power factor improvement over the range reactive power rating of the passive filter. Design guidelines are presented for various values of power

Paderborn, Universität

229

Low forward drop JBS rectifiers fabricated using submicron technology  

Microsoft Academic Search

This paper demonstrates the impact of using submicron technology (0.5 ?m design rules) on JBS Rectifiers to achieve very low forward voltage drops while maintaining good high temperature reverse blocking characteristics. Two dimensional numerical simulations show that decreasing P+-junction width and depth improves the on-state voltage drop by improved utilization of the active area for the Schottky region and improved

Manoj Mehrotra; B. Jayant Baliga

1994-01-01

230

Silicon Photo-Multiplier radiation hardness tests with a beam controlled neutron source  

E-print Network

We report radiation hardness tests performed at the Frascati Neutron Generator on silicon Photo-Multipliers, semiconductor photon detectors built from a square matrix of avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to 7x10^10 1-MeV-equivalent neutrons per cm^2. Detector performances have been recorded during the neutron irradiation and a gradual deterioration of their properties was found to happen already after an integrated fluence of the order of 10^8 1-MeV-equivalent neutrons per cm^2.

M. Angelone; M. Pillon; R. Faccini; D. Pinci; W. Baldini; R. Calabrese; G. Cibinetto; A. Cotta Ramusino; R. Malaguti; M. Pozzati

2010-06-08

231

Bias-controlled friction of InAs nanowires on a silicon nitride layer studied by atomic force microscopy  

NASA Astrophysics Data System (ADS)

By studying how nanowires lying on a surface bend when pushed by an atomic force microscopy tip we are able to measure the friction between them and the substrate. Here, we show how the friction between InAs nanowires and an insulating silicon nitride layer varies when a dc voltage is applied to the tip during manipulation. The bias charges the capacitor formed by the wire and the grounded silicon back contact. Electrostatic forces increase the contact pressure and allow us to tune the friction between the wire and the silicon nitride surface. Using nanowires of about 40-70 nm diameter and a few microns in length we have applied biases in the range +12 to -12V . A monotonic increase of the sliding friction with voltage was observed. This increase in friction with the normal force implies that the mesoscopic nanowire-surface system behaves like a macroscopic contact, despite the nanometer size of the contact in the direction of motion. The demonstrated bias-controlled friction has potential applications in MEMS/NEMS devices.

Conache, G.; Ribayrol, A.; Frberg, L. E.; Borgstrm, M. T.; Samuelson, L.; Montelius, L.; Pettersson, H.; Gray, S. M.

2010-07-01

232

Rectified Cell Migration on Saw-Like Micro-Elastically Patterned Hydrogels with Asymmetric Gradient Ratchet Teeth  

PubMed Central

To control cell motility is one of the essential technologies for biomedical engineering. To establish a methodology of the surface design of elastic substrate to control the long-range cell movements, here we report a sophisticated cell culture hydrogel with a micro-elastically patterned surface that allows long-range durotaxis. This hydrogel has a saw-like pattern with asymmetric gradient ratchet teeth, and rectifies random cell movements. Durotaxis only occurs at boundaries in which the gradient strength of elasticity is above a threshold level. Consequently, in gels with unit teeth patterns, durotaxis should only occur at the sides of the teeth in which the gradient strength of elasticity is above this threshold level. Therefore, such gels are expected to support the long-range biased movement of cells via a mechanism similar to the Feynman-Smoluchowski ratchet, i.e., rectified cell migration. The present study verifies this working hypothesis by using photolithographic microelasticity patterning of photocurable gelatin gels. Gels in which each teeth unit was 100120 m wide with a ratio of ascending:descending elasticity gradient of 1:2 and a peak elasticity of ca. 100 kPa supported the efficient rectified migration of 3T3 fibroblast cells. In addition, long-range cell migration was most efficient when soft lanes were introduced perpendicular to the saw-like patterns. This study demonstrates that asymmetric elasticity gradient patterning of cell culture gels is a versatile means of manipulating cell motility. PMID:24147112

Kidoaki, Satoru; Sakashita, Hiroyuki

2013-01-01

233

Silicon Wafer Lapping  

NSDL National Science Digital Library

This Quicktime animation shows how the machining process of "lapping" removes controlled amounts of silicon from a wafer in order to ensure flatness of the silicon wafer. This process removes particles and improves the quality of the wafer after they are cut. This animation is the fifth in a series of how silicon wafers are created.The previous animation showing silicon ingot edge profiling can be seen here.The next animation in this sequence about silicon wafer polishing can be seen here.

2010-02-08

234

Electronic transport in ordered silicon nanocrystal networks.  

E-print Network

??The present work deals with the structural and electrical characterization of size-controlled silicon nanocrystals. Superlattices consisting of alternating layers of silicon-rich oxynitride and silicon oxide (more)

Gutsch, Sebastian

2014-01-01

235

Amorphous Silicon(aSi:H) Thin Film Based Omnidirectional Control Solar Powered Vehicle  

Microsoft Academic Search

Through the paper, our goal is to drive a car with the help of thin film based solar cell. Mechanical and Electrical parts are assembled thereby. The main objective of this project is to collect maximum solar energy from the solar spectrum and use that solar energy to drive the car. Amorphous silicon based thin film solar panel has been

Abdullah Moinuddin; Jony C. Sarker; Akhter Zia

2012-01-01

236

Voltage-controlling mechanisms in low-resistivity silicon solar cells - A unified approach  

NASA Technical Reports Server (NTRS)

An experimental technique is used to determine the relative values of the base and emitter components of the dark saturation current of six types of high-voltage low-resistivity silicon solar cells. One of the surprising findings is the suggestion that the magnitude of the minority-carrier mobility may be process-dependent.

Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

1986-01-01

237

Peak position control of Coulomb blockade oscillations in silicon single-electron transistors with floating gate operating at room temperature  

NASA Astrophysics Data System (ADS)

A silicon single-electron transistor (SET) with a floating gate (FG) that covers the entire SET structure is proposed and fabricated to study a nonvolatile and precise peak shift of Coulomb blockade oscillations. Large Coulomb blockade oscillations with a peak-to-valley current ratio as high as 14.1, a parallel peak position control without a change in peak height, and a long retention time of over one month are successfully demonstrated at room temperature. The proposed FG SET is suitable for hybrid SET/CMOS circuits for adding more functionalities into future very large scale integration (VLSI) devices.

Tanahashi, Yuma; Suzuki, Ryota; Saraya, Takuya; Hiramoto, Toshiro

2014-01-01

238

A novel method for gas flow and impurity control in directional solidification of multi-crystalline silicon  

NASA Astrophysics Data System (ADS)

In this paper the potential of a specially designed argon gas injector for controlling the gas flow and transport of impurities in directional solidification of multi-crystalline silicon is evaluated. The gas injector which consists of a valve allows one to control the flow direction independently in the vertical and horizontal directions. Based on a gas flow model derived from a semi-industrial crystallization furnace the impact of different gas injection combinations on the gas flow pattern and impurity transport is studied. Special focus is given to the SiO evacuation from the melt-free surface, the CO formation at graphite surfaces and the CO evacuation from the furnace interior. It is found that for gas flow pattern formed through horizontal rather than vertical gas injection, SiO and CO are evacuated most effectively from the furnace interior and the formation of CO is inhibited. Such a type of gas injector presents a versatile tool for controlling the flow and impurity transport in the gas phase and possibly improving the material properties of crystalline silicon.

Bellmann, M. P.; Lindholm, D.; M'Hamdi, M.

2014-08-01

239

Voltage-dependent Inwardly Rectifying Potassium Conductance in the Outer Membrane of Neuronal Mitochondria*  

PubMed Central

Potassium fluxes integrate mitochondria into cellular activities, controlling their volume homeostasis and structural integrity in many pathophysiological mechanisms. The outer mitochondrial membrane (OMM) is thought to play a passive role in this process because K+ is believed to equilibrate freely between the cytosol and mitochondrial intermembrane space. By patch clamping mitochondria isolated from the central nervous systems of adult mitoCFP transgenic mice, we discovered the existence of IOMMKi, a novel voltage-dependent inwardly rectifying K+ conductance located in the OMM. IOMMKi is regulated by osmolarity, potentiated by cAMP, and activated at physiological negative potentials, allowing K+ to enter the mitochondrial intermembrane space in a controlled regulated fashion. The identification of IOMMKi in the OMM supports the notion that a membrane potential could exist across this membrane in vivo and suggests that the OMM possesses regulated pathways for K+ uptake. PMID:20551319

Fieni, Francesca; Parkar, Anjum; Misgeld, Thomas; Kerschensteiner, Martin; Lichtman, Jeff W.; Pasinelli, Piera; Trotti, Davide

2010-01-01

240

Process for fabricating device structures for real-time process control of silicon doping  

DOEpatents

Silicon device structures designed to allow measurement of important doping process parameters immediately after the doping step has occurred. The test structures are processed through contact formation using standard semiconductor fabrication techniques. After the contacts have been formed, the structures are covered by an oxide layer and an aluminum layer. The aluminum layer is then patterned to expose the contact pads and selected regions of the silicon to be doped. Doping is then performed, and the whole structure is annealed with a pulsed excimer laser. But laser annealing, unlike standard annealing techniques, does not effect the aluminum contacts because the laser light is reflected by the aluminum. Once the annealing process is complete, the structures can be probed, using standard techniques, to ascertain data about the doping step. Analysis of the data can be used to determine probable yield reductions due to improper execution of the doping step and thus provide real-time feedback during integrated circuit fabrication.

Weiner, Kurt H. (San Jose, CA)

2001-01-01

241

Controlled release of indomethacin from alginate-poloxamer-silicon carbide composites decrease in-vitro inflammation.  

PubMed

Composites of biomorphic silicon carbides (bioSiCs) and hydrogels are proposed in order to obtain materials able to load and release poor soluble drugs with application in bone pathologies therapy. Hydrogels composed by alginate and poloxamer were loaded with indomethacin, incorporated into the ceramics and crosslinked. The indomethacin release profile is dependent on the microstructure of the bioSiC selected. The loaded oak and sapelli bioSiCs composites have adequate release profiles to promote the decreasing of the secretion of pro-inflammatory cytokines in LPS stimulated macrophages, showing stronger anti-inflammatory effects than pine bioSiC composites. The released indomethacin is able to modulate the degradation of chondrocytes extracellular matrix and promote the formation of new collagen by osteoarthritic chondrocytes. Particles derived from mechanical wear of biomorphic silicon carbides do not show high toxicity, being similar to the zirconia particles. PMID:25596416

Daz-Rodrguez, P; Landin, M

2015-03-01

242

Circuit topologies for single-phase voltage-doubler boost rectifiers  

Microsoft Academic Search

A new family of single-phase voltage-doubler PWM (pulse width modulated) boost rectifiers is presented. By examining the switching states of several standard single-phase boost rectifier circuits, three characteristic PWM voltage switching patterns are identified: unipolar PWM; bipolar PWM; and phase-adjusted unipolar PWM. From this analysis, an equivalent family of voltage-doubler rectifiers is derived. When high output voltages are required, voltage-doubler

John C. Salmon

1993-01-01

243

A Hybrid Driving Scheme for Full-Bridge Synchronous Rectifier in LLC Resonant Converter  

Microsoft Academic Search

The LLC resonant converter with a full-bridge rectifier can achieve two balanced outputs with a simple balancing capacitor, which is quite attractive for LED driver application. To further improve the efficiency, synchronous rectification is an effective way to reduce the conduction loss of the rectifier. In this paper, a new hybrid driving scheme for full-bridge-type synchronous rectifier (SR) in LLC

Junming Zhang; Jianfeng Wang; Guoxing Zhang; Zhaoming Qian

2012-01-01

244

Donor ionization in size controlled silicon nanocrystals: The transition from defect passivation to free electron generation  

NASA Astrophysics Data System (ADS)

We studied the photoluminescence spectra of silicon and phosphorus co-implanted silica thin films on (100) silicon substrates as a function of isothermal annealing time. The rapid phase segregation, formation, and growth dynamics of intrinsic silicon nanocrystals are observed, in the first 600 s of rapid thermal processing, using dark field mode X-TEM. For short annealing times, when the nanocrystal size distribution exhibits a relatively small mean diameter, formation in the presence of phosphorus yields an increase in the luminescence intensity and a blue shift in the emission peak compared with intrinsic nanocrystals. As the mean size increases with annealing time, this enhancement rapidly diminishes and the peak energy shifts further to the red than the intrinsic nanocrystals. These results indicate the existence of competing pathways for the donor electron, which depends strongly on the nanocrystal size. In samples containing a large density of relatively small nanocrystals, the tendency of phosphorus to accumulate at the nanocrystal-oxide interface means that ionization results in a passivation of dangling bond (Pb-centre) type defects, through a charge compensation mechanism. As the size distribution evolves with isothermal annealing, the density of large nanocrystals increases at the expense of smaller nanocrystals, through an Ostwald ripening mechanism, and the majority of phosphorus atoms occupy substitutional lattice sites within the nanocrystals. As a consequence of the smaller band-gap, ionization of phosphorus donors at these sites increases the free carrier concentration and opens up an efficient, non-radiative de-excitation route for photo-generated electrons via Auger recombination. This effect is exacerbated by an enhanced diffusion in phosphorus doped glasses, which accelerates silicon nanocrystal growth.

Crowe, I. F.; Papachristodoulou, N.; Halsall, M. P.; Hylton, N. P.; Hulko, O.; Knights, A. P.; Yang, P.; Gwilliam, R. M.; Shah, M.; Kenyon, A. J.

2013-01-01

245

Pore structure control of starch processed silicon nitride porous ceramics with near-zero shrinkage  

Microsoft Academic Search

Zirconium phosphate (ZrP2O7) bonded silicon nitride (Si3N4) porous ceramics were prepared using starch powder as the pore forming agent and pressureless sintering technique. The obtained results show that the porosity of the sintered starch processed 25wt.% ZrP2O7 bonded Si3N4 porous ceramics is 3662.3%. All the samples exhibit surprisingly low linear shrinkage. The pores are formed by the continuous reaction of

Fei Chen; Lingling Ma; Qiang Shen; Lianmeng Zhang

2011-01-01

246

Microfluidic assembly of multistage porous siliconlipid vesicles for controlled drug release  

PubMed Central

A reliable microfluidic platform for the generation of stable and monodisperse multistage drug delivery systems is reported. A glass-capillary flow-focusing droplet generation device was used to encapsulate thermally hydrocarbonized porous silicon (PSi) microparticles into the aqueous cores of double emulsion drops, yielding the formation of a multistage PSi-lipid vesicle. This composite system enables a large loading capacity for hydrophobic drugs. PMID:24469311

Herranz-Blanco, Brbara; Arriaga, Laura R.; Mkil, Ermei; Correia, Alexandra; Shrestha, Neha; Mirza, Sabiruddin; Weitz, David A.; Salonen, Jarno; Hirvonen, Jouni; Santos, Hlder A.

2014-01-01

247

Control of interface fracture in silicon nitride ceramics: influence of different rare earth elements  

Microsoft Academic Search

The toughness of self-reinforced silicon nitride ceramics is improved by enhancing crack deflection and crack bridging mechanisms. Both mechanisms rely on the interfacial debonding process between the elongated -SiN grains and the intergranular amorphous phases. The various sintering additives used for densification may influence the interfacial debonding process by modifying the thermal and mechanical properties of the intergranular glasses, which

E. Y. Sun; P. F. Becher; S. B. Waters; Chun-Hway Hsueh; K. P. Plucknett; M. J. Hoffmann

1996-01-01

248

Silicon nanocrystals in SiN{sub x}/SiO{sub 2} hetero-superlattices: The loss of size control after thermal annealing  

SciTech Connect

Superlattices containing 3?nm thick silicon rich silicon nitride sublayers and 3?nm and 10?nm thick SiO{sub 2} barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3?nm SiO{sub 2} barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.512.5?nm, which were randomly distributed within the structure. Although in the sample with 10?nm SiO{sub 2} barriers some fragments of the multilayer structure could be still observed after thermal annealing, nevertheless, the formation of large nanocrystals with diameters up to 10?nm was confirmed by dark field transmission electron microscopy. Thus, in contrast to the previously published results, the expected size control of silicon nanocrystals was lost. According to the FTIR results, the thermal annealing of SiN{sub x}/SiO{sub 2} superlattices led to the formation of silicon nanocrystals in mostly oxynitride matrix. Annealed samples demonstrated a photoluminescence peak at 885?nm related to the luminescence of silicon nanocrystals, as confirmed by time-resolved photoluminescence measurements. The loss of nanocrystals size control is discussed in terms of the migration of oxygen atoms from the SiO{sub 2} barriers into the silicon rich silicon nitride sublayers. A thermodynamic mechanism responsible for this process is proposed. According to this mechanism, the driving force for the oxygen migration is the gain in the configuration entropy related to the relative arrangements of oxygen and nitrogen atoms.

Zelenina, A., E-mail: anastasia.zelenina@imtek.uni-freiburg.de; Zacharias, M. [Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Khler-Allee 103, Freiburg 79110 (Germany); Sarikov, A. [Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Khler-Allee 103, Freiburg 79110 (Germany); V. Lashkarev Institute of Semiconductor Physics NAS Ukraine, 45 Nauki Avenue, Kiev 03028 (Ukraine); Zhigunov, D. M. [Faculty of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory 1, Moscow 119991 (Russian Federation); Weiss, C. [Fraunhofer-Institut fr Solare Energiesysteme ISE, Heidenhofstr. 2, Freiburg 79110 (Germany); Zakharov, N.; Werner, P. [Max-Planck-Institute of Microstructure Physics, Weinberg 2, Halle 06120 (Germany); Lpez-Conesa, L.; Peir, F. [MIND-IN2UB, Departament d'Electrnica, Universitat de Barcelona, C/Mart i Franqus, 1, Barcelona 08028 (Spain); Estrad, S. [MIND-IN2UB, Departament d'Electrnica, Universitat de Barcelona, C/Mart i Franqus, 1, Barcelona 08028 (Spain); CCiT, Scientific and Technical Centers, Universitat de Barcelona, C/Llus Sol i Sabaris 1, Barcelona 08028 (Spain); Dyakov, S. A. [Optics and Photonics, School of Information and Communication Technology, Royal Institute of Technology (KTH), Electrum 229, Kista SE-16440 (Sweden)

2014-06-28

249

A unique P-region residue is required for slow voltage-dependent gating of a G protein-activated inward rectifier K+ channel expressed in Xenopus oocytes.  

PubMed Central

1. The structural determinants of a G protein-activated inwardly rectifying potassium channel, GIRK1 (KIR3.1), involved in voltage- and time-dependent gating properties were investigated by heterologous expression of chimeric constructs and point mutants in Xenopus oocytes. 2. Chimeras between GIRK1 and the weakly rectifying potassium channel, ROMK1 (KIR1.1), indicate that residues in the putative transmembrane segments TM1 and TM2 affect the steep inward rectification of GIRK1, while residues in the main pore-forming domain, the P-region segment, are critical for the manifestation of GIRK1 time-dependent activation. 3. Phenylalanine 137 in the P-region of GIRK1 is unique; in ROMK1, as in other inward rectifiers, there is a serine residue at this position. Mutation of the phenylalanine 137 to serine leads to expression of currents with nearly time-independent activation. 4. An acidic residue (aspartate) in TM2 partially controls the time- and voltage-dependent gating in IRK1 (KIR2.1). Mutation of the equivalent aspartate 173 to glutamine in GIRK1 did not abolish the time-dependent activation but did decrease the degree of inward rectification. 5. These results reveal an important role for the P-region in controlling the time-dependent gating of an inwardly rectifying potassium channel and suggest a close relationship between permeation and gating in this family of K+ channels. PMID:8683463

Kofuji, P; Doupnik, C A; Davidson, N; Lester, H A

1996-01-01

250

Performance of Thin-Window Silicon Drift Detectors  

SciTech Connect

Several sets of hexagonal Silicon Drift Detector (SDD) arrays were produced at BNL and by a commercial vendor, KETEK. Each array consists of 14 independent detectors (pixels) and two additional test pixels at two of the corners. The side of the detector upon which the X-ray radiation is incident (window side) has a thin junction covering the entire active area. The opposite side (device side) contains a drift-field electrode structure in the form of a hexagonal spiral and an electron collecting anode. There are 4 guard rings surrounding the 14-pixel array area on both sides of the detector. Within each array, 7 of the pixels have an aluminum field plate - interrupted spirals that stabilize the electric potential under the Si-SiO2 interface, while the other 7 do not. The drift field in the silicon volume is controlled by three biases: one is applied to a rectifying contact, one to the detector entrance window, and the third to a contact on the outer portion of the spiral common to all pixels in the array. Some arrays have been newly measured in NSLS beam line U3C at BNL. The complete assemblies were installed in the vacuum and cooled to ?27 C. During this run, spectra for energies ranging between 400 and 900 eV were collected in several pixels, some with field plates and others without. The detailed testing results of several arrays are reported here.

Carini, , G.A.; Chen, W.; De Geronimo, G.; Fried, J.; Gaskin, J.A.; Keister; J.W.; Li, Z.; Ramsey, B.D.; Rehak, P.; Siddons, D.P.

2008-10-20

251

Rectifying calibration error of Goldmann applanation tonometer is easy!  

PubMed Central

Purpose: Goldmann applanation tonometer (GAT) is the current Gold standard tonometer. However, its calibration error is common and can go unnoticed in clinics. Its company repair has limitations. The purpose of this report is to describe a self-taught technique of rectifying calibration error of GAT. Materials and Methods: Twenty-nine slit-lamp-mounted Haag-Streit Goldmann tonometers (Model AT 900 C/M; Haag-Streit, Switzerland) were included in this cross-sectional interventional pilot study. The technique of rectification of calibration error of the tonometer involved cleaning and lubrication of the instrument followed by alignment of weights when lubrication alone didnt suffice. We followed the South East Asia Glaucoma Interest Group's definition of calibration error tolerance (acceptable GAT calibration error within 2, 3 and 4 mm Hg at the 0, 20 and 60-mm Hg testing levels, respectively). Results: Twelve out of 29 (41.3%) GATs were out of calibration. The range of positive and negative calibration error at the clinically most important 20-mm Hg testing level was 0.5 to 20 mm Hg and -0.5 to -18 mm Hg, respectively. Cleaning and lubrication alone sufficed to rectify calibration error of 11 (91.6%) faulty instruments. Only one (8.3%) faulty GAT required alignment of the counter-weight. Conclusions: Rectification of calibration error of GAT is possible in-house. Cleaning and lubrication of GAT can be carried out even by eye care professionals and may suffice to rectify calibration error in the majority of faulty instruments. Such an exercise may drastically reduce the downtime of the Gold standard tonometer. PMID:25494251

Choudhari, Nikhil S; Moorthy, P Krishna; Tungikar, Vinod B; Kumar, Mohan; George, Ronnie; Rao, Harsha L; Senthil, Sirisha; Vijaya, Lingam; Garudadri, Chandra Sekhar

2014-01-01

252

Bicarbonate permeability of the outwardly rectifying anion channel.  

PubMed

Single anion-selective channels have been studied in cultured human epithelial cells using the patch-clamp technique. Three cell types were used as models for different anion transport systems: (i) PANC-1, a cell line derived from the pancreatic duct, (ii) T84, a Cl-secreting colonic cell line, and (iii) primary cultures of sweat duct epithelium. Outwardly rectifying anion-selective channels were observed in all three preparations and were indistinguishable with respect to conductance, selectivity and gating. Striking similarities between HCO3- and Cl-secreting epithelia, and the high density of outward rectifiers in pancreatic cells prompted us to study HCO3 permeation through this channel. HCO3 permeability was significant when channels were bathed in symmetrical 150 mM HCO3 solutions, Cl-HCO3 mixtures, and under bi-ionic conditions with outwardly and inwardly directed HCO3 gradients. Permeability ratios (PHCO3/PCl) estimated from bi-ionic reversal potentials ranged from 0.50 to 0.64, although conductance ratios greater than 1.2 were observed with high extracellular pH. Chloride did not inhibit HCO3 permeation noticeably but rather had a small stimulatory effect when present on the opposite side of the membrane. The prevalence of outward rectifiers in PANC-1 and their permeability to bicarbonate suggests the channel may have a dual role in HCO3 secretion; to allow Cl recycling at the apical membrane and to mediate some of the HCO3 flux. Defective modulation of this channel in cystic fibrosis might provide a common basis for dysfunction in epithelia having very different anion transport properties (e.g., HCO3 secretion, Cl secretion and Cl absorption. PMID:2482894

Tabcharani, J A; Jensen, T J; Riordan, J R; Hanrahan, J W

1989-12-01

253

Directed drop transport rectified from orthogonal vibrations via a flat wetting barrier ratchet.  

PubMed

We introduce the wetting barrier ratchet, a digital microfluidic technology for directed drop transport in an open air environment. Cyclic drop footprint oscillations initiated by orthogonal vibrations as low as 37 ?m in amplitude at 82 Hz are rectified into fast (mm/s) and controlled transport along a fabricated ratchet design. The ratchet is made from a simple wettability pattern atop a microscopically flat surface consisting of periodic semi-circular hydrophilic features on a hydrophobic background. The microfluidic ratchet capitalizes on the asymmetric contact angle hysteresis induced by the curved features to drive transport. In comparison to the previously reported texture ratchets, wetting barrier ratchets require 3-fold lower actuation amplitudes for a 10 ?L drop, have a simplified fabrication, and can be made optically flat for applications where transparency is paramount. PMID:22934529

Duncombe, Todd A; Parsons, James F; Bhringer, Karl F

2012-09-25

254

Plasma monitoring and PECVD process control in thin film silicon-based solar cell manufacturing  

NASA Astrophysics Data System (ADS)

A key process in thin film silicon-based solar cell manufacturing is plasma enhanced chemical vapor deposition (PECVD) of the active layers. The deposition process can be monitored in situ by plasma diagnostics. Three types of complementary diagnostics, namely optical emission spectroscopy, mass spectrometry and non-linear extended electron dynamics are applied to an industrial-type PECVD reactor. We investigated the influence of substrate and chamber wall temperature and chamber history on the PECVD process. The impact of chamber wall conditioning on the solar cell performance is demonstrated.

Gabriel, Onno; Kirner, Simon; Klick, Michael; Stannowski, Bernd; Schlatmann, Rutger

2014-02-01

255

Control of interface fracture in silicon nitride ceramics: influence of different rare earth elements  

SciTech Connect

The toughness of self-reinforced silicon nitride ceramics is improved by enhancing crack deflection and crack bridging mechanisms. Both mechanisms rely on the interfacial debonding process between the elongated {Beta}-Si{sub 3}N{sub 4} grains and the intergranular amorphous phases. The various sintering additives used for densification may influence the interfacial debonding process by modifying the thermal and mechanical properties of the intergranular glasses, which will result in different residual thermal expansion mismatch stresses; and the atomic bonding structure across the {Beta}-Si{sub 3}N{sub 4} glass interface. Earlier studies indicated that self-reinforced silicon nitrides sintered with different rare earth additives and/or different Y{sub 2}O{sub 3}:AI{sub 2}0{sub 3} ratios could exhibit different fracture behavior that varied from intergranular to transgranular fracture. No studies have been conducted to investigate the influence of sintering additives on the interfacial fracture in silicon nitride ceramics. Because of the complexity of the material system and the extremely small scale, it is difficult to conduct quantitative analyses on the chemistry and stress states of the intergranular glass phases and to relate the results to the bulk properties. The influence of different sintering additives on the interfacial fracture behavior is assessed using model systems in which {Beta}-Si{sub 3}N{sub 4}whiskers are embedded in SIAIRE (RE: rare-earth) oxynitride glasses. By systematically varying the glass composition, the role of various rare-earth additives on interfacial fracture has been examined. Specifically, four different additives were investigated: Al{sub 2}0{sub 3}, Y{sub 2}0{sub 3}, La{sub 2}O{sub 3}, and Yb{sub 2}O{sub 3}. In addition, applying the results from the model systems, the R- curve behavior of self-reinforced silicon nitride ceramics sintered with different Y{sub 2}0{sub 3}:AI{sub 2}0{sub 3} ratios was characterized.

Sun, E.Y.; Becher, P.F.; Waters, S.B.; Hsueh, Chun-Hway; Plucknett, K.P. [Oak Ridge National Lab., TN (United States); Hoffmann, M.J. [Karlsruhe Univ. (T.H.) (Germany). Inst. fuer Keramik im Maschinenbau

1996-10-01

256

Porosity control in metal-assisted chemical etching of degenerately doped silicon nanowires This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Porosity control in metal-assisted chemical etching of degenerately doped silicon nanowires.1088/0957-4484/23/30/305304 Porosity control in metal-assisted chemical etching of degenerately doped silicon nanowires Karthik reduction in the porosity of these nanowires by adjusting the etching solution composition and temperature

Rogers, John A.

257

Highly sensitive silicon nanowire biosensor with novel liquid gate control for detection of specific single-stranded DNA molecules.  

PubMed

The study demonstrates the development of a liquid-based gate-control silicon nanowire biosensor for detection of specific single-stranded DNA (ssDNA) molecules. The sensor was fabricated using conventional photolithography coupled with an inductively coupled plasma dry etching process. Prior to the application of DNA to the device, its linear response to pH was confirmed by serial dilution from pH 2 to pH14. Then, the sensor surface was silanized and directly aminated with (3-aminopropyl) triethoxysilane to create a molecular binding chemistry for biofunctionalization. The resulting Si?O?Si? components were functionalized with receptor ssDNA, which interacted with the targeted ssDNA to create a field across the silicon nanowire and increase the current. The sensor shows selectivity for the target ssDNA in a linear range from target ssDNA concentrations of 100pM to 25nM. With its excellent detection capabilities, this sensor platform is promising for detection of specific biomarkers and other targeted proteins. PMID:25453738

Adam, Tijjani; Hashim, U

2015-05-15

258

Enhanced photocurrent in thin-film amorphous silicon solar cells via shape controlled three-dimensional nanostructures.  

PubMed

In this paper, we have explored manufacturable approaches to sub-wavelength controlled three-dimensional (3D) nano-patterns with the goal of significantly enhancing the photocurrent in amorphous silicon solar cells. Here we demonstrate efficiency enhancement of about 50% over typical flat a-Si thin-film solar cells, and report an enhancement of 20% in optical absorption over Asahi textured glass by fabricating sub-wavelength nano-patterned a-Si on glass substrates. External quantum efficiency showed superior results for the 3D nano-patterned thin-film solar cells due to enhancement of broadband optical absorption. The results further indicate that this enhanced light trapping is achieved with minimal parasitic absorption losses in the deposited transparent conductive oxide for the nano-patterned substrate thin-film amorphous silicon solar cell configuration. Optical simulations are in good agreement with experimental results, and also show a significant enhancement in optical absorption, quantum efficiency and photocurrent. PMID:22997169

Hilali, Mohamed M; Yang, Shuqiang; Miller, Mike; Xu, Frank; Banerjee, Sanjay; Sreenivasan, S V

2012-10-12

259

Silicone metalization  

DOEpatents

A system for providing metal features on silicone comprising providing a silicone layer on a matrix and providing a metal layer on the silicone layer. An electronic apparatus can be produced by the system. The electronic apparatus comprises a silicone body and metal features on the silicone body that provide an electronic device.

Maghribi, Mariam N. (Livermore, CA); Krulevitch, Peter (Pleasanton, CA); Hamilton, Julie (Tracy, CA)

2008-12-09

260

Gate tunable graphene-silicon Ohmic/Schottky contacts  

NASA Astrophysics Data System (ADS)

We show that the I-V characteristics of graphene-silicon junctions can be actively tuned from rectifying to Ohmic behavior by electrostatically doping the graphene with a polymer electrolyte gate. Under zero applied gate voltage, we observe rectifying I-V characteristics, demonstrating the formation of a Schottky junction at the graphene-silicon interface. Through appropriate gating, the Fermi energy of the graphene can be varied to match the conduction or valence band of silicon, thus forming Ohmic contacts with both n- and p-type silicon. Over the applied gate voltage range, the low bias conductance can be varied by more than three orders of magnitude. By varying the top gate voltage from -4 to +4 V, the Fermi energy of the graphene is shifted between -3.78 and -5.47 eV; a shift of 0.85 eV from the charge neutrality point. Since the conduction and valence bands of the underlying silicon substrate lie within this range, at -4.01 and -5.13 eV, the Schottky barrier height and depletion width can be decreased to zero for both n- and p-type silicon under the appropriate top gating conditions. I-V characteristics taken under illumination show that the photo-induced current can be increased or decreased based on the graphene-silicon work function difference.

Chen, Chun-Chung; Chang, Chia-Chi; Li, Zhen; Levi, A. F. J.; Cronin, Stephen B.

2012-11-01

261

Performance of a double-star synchronous generator with bridge rectified output  

Microsoft Academic Search

In this paper, the performance of a double-star synchronous generator with bridge rectified output is studied from the fundamental machine equations. The generator has two stator windings shifted by ?\\/6 electrical radians, which with their bridges can be connected either in series or in parallel. Therefore the double-star synchronous generator with rectifier load can have two major operation modes. Using

Xing-Yuan Li; O. P. Malik

1994-01-01

262

Semiconductor-metal phase transition of vanadium dioxide nanostructures on silicon substrate: Applications for thermal control of spacecraft  

NASA Astrophysics Data System (ADS)

We present a detailed infrared study of the semiconductor-to-metal transition (SMT) in a vanadium dioxide (VO2) film deposited on silicon wafer. The VO2 phase transition is studied in the mid-infrared (MIR) region by analyzing the transmittance and the reflectance measurements, and the calculated emissivity. The temperature behaviour of the emissivity during the SMT put into evidence the phenomenon of the anomalous absorption in VO2 which has been explained by applying the Maxwell Garnett effective medium approximation theory, together with a strong hysteresis phenomenon, both useful to design tunable thermal devices to be applied for the thermal control of spacecraft. We have also applied the photothermal radiometry in order to study the changes in the modulated emissivity induced by laser. Experimental results show how the use of these techniques represent a good tool for a quantitative measurement of the optothermal properties of vanadium dioxide based structures.

Leahu, G. L.; Li Voti, R.; Larciprete, M. C.; Belardini, A.; Mura, F.; Fratoddi, I.; Sibilia, C.; Bertolotti, M.

2014-06-01

263

A passive UHF RFID tag with a dynamic-Vth-cancellation rectifier  

NASA Astrophysics Data System (ADS)

This paper presents a passive UHF RFID tag with a dynamic-Vth-cancellation (DVC) rectifier. In the rectifier, the threshold voltages of MOSFETs are cancelled by applying gate bias voltages, which are dynamically changed according to the states of the MOSFETs. The DVC rectifier enables both low ON-resistance and small reverse leakage of the MOSFETs, resulting in high power conversion efficiency (PCE). An area-efficient demodulator with a novel average detector is also designed, which takes advantage of the rectifier's first stage as the envelope detector. The whole tag chip is implemented in a 0.18 ?m CMOS process with a die size of 880 950 ?m2. Measurement results show that the rectifier achieves a maximum PCE of 53.7% with 80 k? resistor load.

Jinpeng, Shen; Bo, Wang; Shan, Liu; Xin'an, Wang; Zhengkun, Ruan; Shoucheng, Li

2013-09-01

264

Input Power Quality Improvement in Switched Reluctance Motor Drive using Minnesota Rectifier  

NASA Astrophysics Data System (ADS)

This paper deals with an input power quality improvement in a midpoint converter based switched reluctance motor (SRM) drive at ac mains using Minnesota rectifier. Normally a midpoint converter is used as a power converter for SRM drive. Conventionally three phase ac mains fed bridge rectifier is used as a dc source to feed this power converter which produces high content of harmonics at ac mains with a very low power factor. The proposed Minnesota rectifier with a midpoint converter fed SRM drive improves the power factor at ac mains with low current harmonics. This method provides constant dc link voltage and balanced capacitor voltages of the midpoint converter. The Minnesota rectifier fed SRM drive is modelled and its performance is simulated in Matlab/Simulink environment. The performance of Minnesota rectifier is compared with a conventional bridge topology for SRM drive to demonstrate improved power quality at ac mains.

Singh, B.; Rajesh, M.

2013-09-01

265

Voltage controlling mechanisms in low resistivity silicon solar cells - A unified approach  

NASA Technical Reports Server (NTRS)

An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices.

Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

1984-01-01

266

Voltage controlling mechanisms in low resistivity silicon solar cells: A unified approach  

NASA Technical Reports Server (NTRS)

An experimental technique capable of resolving the dark saturation current into its base and emitter components is used as the basis of an analysis in which the voltage limiting mechanisms were determined for a variety of high voltage, low resistivity silicon solar cells. The cells studied include the University of Florida hi-low emitter cell, the NASA and the COMSAT multi-step diffused cells, the Spire Corporation ion-implanted emitter cell, and the University of New South Wales MINMIS and MINP cells. The results proved to be, in general, at variance with prior expectations. Most surprising was the finding that the MINP and the MINMIS voltage improvements are due, to a considerable extent, to a previously unrecognized optimization of the base component of the saturation current. This result is substantiated by an independent analysis of the material used to fabricate these devices.

Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

1984-01-01

267

IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 13, NO. 2, MARCH 1998 213 Nonlinear-Carrier Control for High-Power-Factor  

E-print Network

for High-Power-Factor Rectifiers Based on Up­Down Switching Converters Regan Zane and Dragan Maksimovi-power-factor rectifiers based on flyback, ´Cuk, Sepic, and other up­down converters operated in the continuous conduction the NLC controllers were introduced for rectifiers based on the boost converter. The main idea

268

Foam Control by Silicone Polyethers-Mechanisms of "Cloud Point Antifoaming"  

PubMed

The mechanism of antifoaming in a nonionic Triton X-100 surfactant solution with silicone polyethers (SILWET L-7210, L-7230, and L-7500), the so-called "cloud point antifoams," was investigated. The cloud point (CP) studies showed that the CP of a Triton X-100/silicone polyether mixed system is between the CP of the foaming and the antifoam surfactants, due to mixed micelle formation. It was found that the foam stability drops at a certain temperature-which we called the enhanced foam collapse temperature (EFCT)-which was a few degrees Celsius below the CP of the solutions. Single films were also formed from the same systems, and their stability and drainage were observed. Film thinning accelerated with temperature near the cloud point, but this cannot explain the lower foam stability. It was observed that while at low temperatures black film formed, above the EFCT the film ruptured just before black film formation could have begun; the rupture was probably caused by unstable black spots. It is suggested that at the EFCT (near the CP) the net interaction between the film surfaces becomes attraction due to the same reason that causes the CP: the hydrophilic parts (polyethylene oxide) of the nonionic surfactants lose their hydrate water and thus, the steric repulsion between the surfaces diminishes. The EFCT and the CP are not necessarily the same because the composition of the foam and micelle surfaces, respectively, can be different. The antifoaming action was also tested above the CP of the solution and it was observed that another antifoaming mechanism also acts there: the phase-separated surfactant drops get trapped in the thinning foam films and the trapped drops rupture the films by bridging. Copyright 1998 Academic Press. PMID:9792784

Nmeth; Rcz; Koczo

1998-11-15

269

Cloning, expression, pharmacology and regulation of a delayed rectifier K+ channel in mouse heart.  

PubMed Central

Neonatal mouse cardiac poly(A)+ mRNA microinjection into Xenopus oocytes directed the expression of a delayed rectifier K+ current. A cDNA encoding this channel, called mIsK, was cloned from a neonatal mouse heart cDNA library whose properties were studied after expression of the complementary RNA in Xenopus oocytes. Among the different known K+ channel blockers, only the class III antiarrhythmic clofilium inhibited mIsK in the 10-100 microM range. The channel was completely insensitive to other antiarrhythmics such as quinine, quinidine, sotalol or amiodarone. mIsK was enhanced by increasing intracellular Ca2+ and by microinjected Ca(2+)-calmodulin dependent protein kinase II. These stimulations were reversed by the calmodulin antagonist W7. Conversely, the phorbol ester PMA, the diacylglycerol analog OAG and microinjected purified protein kinase C inhibited mIsK. This inhibitory effect could be prevented by the protein kinase C inhibitor staurosporine. These results were consistent with the presence of consensus sequences for kinase II and kinase C in the mIsK structure. Cultured newborn mouse ventricular cardiac cells exhibited a delayed rectifier K+ current which had biophysical properties similar to those of cloned mIsK and which was inhibited by clofilium and protein kinase C activators. In situ hybridization experiments revealed that mIsK mRNA was homogeneously distributed in the cardiac tissue. Neonatal mouse heart expressed the most mIsK mRNA compared with various other rat and mouse tissues. Since this K+ channel generates a current which appears to be involved in the control of both the action potential duration and the beating rate, these results suggest an important role for the mIsK channel in cardiac cell physiology and cardiac pathology. Images PMID:1655403

Honor, E; Attali, B; Romey, G; Heurteaux, C; Ricard, P; Lesage, F; Lazdunski, M; Barhanin, J

1991-01-01

270

The inward rectifier potassium channel Kir2.1 is required for osteoblastogenesis.  

PubMed

Andersen's syndrome (AS) is a rare and dominantly inherited pathology, linked to the inwardly rectifying potassium channel Kir2.1. AS patients exhibit a triad of symptoms that include periodic paralysis, cardiac dysrhythmia and bone malformations. Some progress has been made in understanding the contribution of the Kir2.1 channel to skeletal and cardiac muscle dysfunctions, but its role in bone morphogenesis remains unclear. We isolated myoblast precursors from muscle biopsies of healthy individuals and typical AS patients with dysmorphic features. Myoblast cultures underwent osteogenic differentiation that led to extracellular matrix mineralization. Osteoblastogenesis was monitored through the activity of alkaline phosphatase, and through the hydroxyapatite formation using Alizarin Red and Von Kossa staining techniques. Patch-clamp recordings revealed the presence of an inwardly rectifying current in healthy cells that was absent in AS osteoblasts, showing the dominant-negative effect of the Kir2.1 mutant allele in osteoblasts. We also found that while control cells actively synthesize hydroxyapatite, AS osteoblasts are unable to efficiently form any extracellular matrix. To further demonstrate the role of the Kir2.1 channels during the osteogenesis, we inhibited Kir2.1 channel activity in healthy patient cells by applying extracellular Ba(2+) or using adenoviruses carrying mutant Kir2.1 channels. In both cases, cells were no longer able to produce extracellular matrixes. Moreover, osteogenic activity of AS osteoblasts was restored by rescue experiments, via wild-type Kir2.1 channel overexpression. These observations provide a proof that normal Kir2.1 channel function is essential during osteoblastogenesis. PMID:25205110

Sacco, Sonia; Giuliano, Serena; Sacconi, Sabrina; Desnuelle, Claude; Barhanin, Jacques; Amri, Ez-Zoubir; Bendahhou, Sad

2015-01-15

271

A unified theory of uncontrolled rectifiers, discharge lamps and arc furnaces. I. An analytical approach for normalized harmonic emission calculations  

Microsoft Academic Search

Under certain assumptions, similar models can be applied for rectifiers and devices with electric arc characteristic. The analysis considers single and three-phase uncontrolled rectifiers with continuous and discontinuous evolution of the AC current. It leads to four possible situations which fit with the harmonic behaviour of discharge lamps, arc furnaces and rectifiers with capacitive DC smoothing. A very useful set

J. G. Mayordomo; A. Hernandez; R. Asensi; L. F. Beites; M. Izzeddine

1998-01-01

272

Ordered Mesostructured CdS Nanowire Arrays with Rectifying Properties  

PubMed Central

Highly ordered mesoporous CdS nanowire arrays were synthesized by using mesoporous silica as hard template and cadmium xanthate (CdR2) as a single precursor. Upon etching silica, mesoporous CdS nanowire arrays were produced with a yield as high as 93 wt%. The nanowire arrays were characterized by XRD, N2adsorption, TEM, and SEM. The results show that the CdS products replicated from the mesoporous silica SBA-15 hard template possess highly ordered hexagonal mesostructure and fiber-like morphology, analogous to the mother template. The currentvoltage characteristics of CdS nanoarrays are strongly nonlinear and asymmetrical, showing rectifying diode-like behavior. PMID:20596434

2009-01-01

273

Rectified Brownian movement in molecular and cell biology  

NASA Astrophysics Data System (ADS)

A unified model is presented for rectified Brownian movement as the mechanism for a variety of putatively chemomechanical energy conversions in molecular and cell biology. The model is established by a detailed analysis of ubiquinone transport in electron transport chains and of allosteric conformation changes in proteins. It is applied to P-type ATPase ion transporters and to a variety of rotary arm enzyme complexes. It provides a basis for the dynamics of actin-myosin cross-bridges in muscle fibers. In this model, metabolic free energy does no work directly, but instead biases boundary conditions for thermal diffusion. All work is done by thermal energy, which is harnessed at the expense of metabolic free energy through the establishment of the asymmetric boundary conditions.

Fox, Ronald F.

1998-02-01

274

Molecular characterization of an inwardly rectifying K+ channel from HeLa cells.  

PubMed

Previous patch-clamp studies have shown that the potassium permeability of the plasma membrane in HeLa cells, a cell line derived from an epidermoid carcinoma of the cervix, is controlled by various K+-selective pores including an IRK1 type inwardly rectifying K+ channel. We used the sequence previously reported for the human heart Kir2.1 channel to design a RT-PCR strategy for cloning the IRK1 channel in HeLa cells. A full-length clone of 1.3 kb was obtained that was identical to the human cardiac Kir2.1 inward rectifier. The nature of the cloned channel was also confirmed in a Northern blot analysis where a signal of 5.3 kb corresponding to the molecular weight expected for a Kir2.1 channel transcript was identified not only in HeLa cells, but also in WI-38, ECV304 and bovine aortic endothelial cells. The HeLa IRK1 channel cDNA was subcloned in an expression vector (pMT21) and injected into Xenopus oocytes. Cell-attached and inside-out single channel recordings obtained from injected oocytes provided evidence for a voltage-independent K+-selective channel with current/voltage characteristics typical of a strong inward rectifier. The single channel conductance for inward currents measured in 200 mm K2SO4 conditions was estimated at 40 +/- 1 pS (n = 3), for applied voltages ranging from -100 to -160 mV, in agreement with the unitary conductance for the IRK1 channel identified in HeLa cells. In addition, the single channel conductance for inward currents, Gamma, was found to vary as a function of alphaK, the external K+ ion activity, according to Gamma = Gamma0 [alphaK]delta with Gamma0 = 3.3 pS and delta = 0.5. Single channel recordings from injected oocytes also provided evidence of a voltage-dependent block by external Cs+ and Ba2+. The presence of 500 micron Cs+ caused a voltage-dependent flickering, typical of a fast channel blocking process which resulted in a reduction of the channel open probability at increasingly negative membrane potential values. The fractional electrical distance computed for the Cs+ blocking site was greater than 1 indicating a multiple ion channel occupation. In contrast, external Ba2+ at concentrations ranging from 25 to 100 micron caused a slow channel block, consistent with the binding of a single Ba2+ ion at a site located at half the membrane span. It is concluded on the basis of these observations that HeLa cells expressed a Kir2.1 type inwardly rectifying channel likely to be involved in maintaining and regulating the cell resting potential. PMID:9878074

Klein, H; Garneau, L; Coady, M; Lemay, G; Lapointe, J Y; Sauv, R

1999-01-01

275

Adjustable Lid Aids Silicon-Ribbon Growth  

NASA Technical Reports Server (NTRS)

Closely-spaced crucible cover speeds up solidification. Growth rate of dendritic-web silicon ribbon from molten silicon increased by controlling distance between crucible susceptor lid and liquid/solid interface. Lid held in relatively high position when crucible newly filled with chunks of polycrystalline silicon. As silicon melts and forms pool of liquid at lower level, lid gradually lowered.

Mchugh, J. P.; Steidensticker, R. G.; Duncan, C. S.

1985-01-01

276

Strained-Silicon on Silicon and Strained-Silicon on Silicon-Germanium on Silicon by Relaxed  

E-print Network

Strained-Silicon on Silicon and Strained-Silicon on Silicon-Germanium on Silicon by Relaxed Buffer platforms: strained-silicon on silicon SSOS and strained-silicon on silicon-germanium on silicon SGOS . SSOS substrate has an epitaxially defined, strained- silicon layer directly on silicon wafer without

277

Analysis of three-phase rectifiers with AC-side switches and interleaved three-phase voltage-source converters  

NASA Astrophysics Data System (ADS)

Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage-source converters is also analyzed. The low frequency circulating current characteristics of abc, dq, and nonlinear average current control are determined and experimental results for the nonlinear average current control are presented.

Miller, Stephanie Katherine Teixeira

278

An RF energy harvester system using UHF micropower CMOS rectifier based on a diode connected CMOS transistor.  

PubMed

This paper presents a new type diode connected MOS transistor to improve CMOS conventional rectifier's performance in RF energy harvester systems for wireless sensor networks in which the circuits are designed in 0.18? ?m TSMC CMOS technology. The proposed diode connected MOS transistor uses a new bulk connection which leads to reduction in the threshold voltage and leakage current; therefore, it contributes to increment of the rectifier's output voltage, output current, and efficiency when it is well important in the conventional CMOS rectifiers. The design technique for the rectifiers is explained and a matching network has been proposed to increase the sensitivity of the proposed rectifier. Five-stage rectifier with a matching network is proposed based on the optimization. The simulation results shows 18.2% improvement in the efficiency of the rectifier circuit and increase in sensitivity of RF energy harvester circuit. All circuits are designed in 0.18 ?m TSMC CMOS technology. PMID:24782680

Shokrani, Mohammad Reza; Khoddam, Mojtaba; Hamidon, Mohd Nizar B; Kamsani, Noor Ain; Rokhani, Fakhrul Zaman; Shafie, Suhaidi Bin

2014-01-01

279

Fluorescence of silicon nanoparticles suspended in water: reactive co-deposition for the control of surface properties of clusters  

Microsoft Academic Search

Fluorescent silicon nanoparticles have been produced in a two-step process in ultra high vacuum. First, silicon clusters were produced in the gas phase in a molecular beam. At the end of the cluster beam machine the cluster were co-deposited with water onto a cold target. Melting of the ice yields a suspension that fluoresces at 420 nm when excited with

K. von Haeften; A. Akraiam; G. Torricelli; A. Brewer

2010-01-01

280

Comparative studies of direct photovoltaic and AC rectified power supplies for battery charging  

SciTech Connect

The Clean Energy and Vehicle Research Center at the University of South Florida (USF) is operating a 20 kW (peak) photovoltaic (PV) system in which PV panels form the roof of a 12 bay carport. 4 of the 12 bays has a potential 6kW output that can be used for simultaneous computer controlled direct DC-DC charging and utility interconnection. The program has been created to evaluate the potential contribution of photovoltaics as a method for offsetting the fuel cost of electric vehicles while reducing air pollution generated by power plants, that are fueled by non-renewable sources. When charging lead acid batteries in an EV, a large percentage (22%--40%) of the charging power is lost, which raises the cost of operation. The charger losses usually include power conditioning, power factor, and heat losses, which cumulatively can range between 3%--25%. However, this loss is not a constant and can be affected by the charging process. To determine the impact that charging has on battery losses, two chargers with different power conditioning and charging algorithms will be used under controlled conditions. The battery pack is a 120V 183Ah (5 hr rate) flooded lead acid system located in a Chevy S-10 EV. The first charger (charger A) derives its power from the 6kW photovoltaic array. This charger is computer controlled and prevents gassing throughout the entire charge. This power is pure DC with no ripple. The second charger (charger B) derives its power from the 208V single phase AC grid. This power is condition through a transformer and then rectified with no filtering. The charger conducts only when the rectified voltage exceeds that of the battery pack, which results in the output consisting of current ripples. Test results will be presented to show the extent the ripple power of charger B causes losses in the battery pack, how it influences the battery temperature and the extra losses associated during the gassing phase.

Lamb, H.; Stefanakos, E.; Arbogast, T.; Smith, T. [Univ. of South Florida, Tampa, FL (United States). Clean Energy and Vehicle Research Center

1995-12-31

281

Design of resistive-input class E resonant rectifiers for variable-power operation  

E-print Network

Resonant rectifiers have important application in very-high-frequency power conversion systems, including dc-dc converters, wireless power transfer systems, and energy recovery circuits for radio-frequency systems. In many ...

Perreault, David J.

282

Switched-capacitor step-down rectifier for low-voltage power conversion  

E-print Network

This paper presents a switched-capacitor rectifier that provides step down voltage conversion from an ac input voltage to a dc output. Coupled with current-drive source, low-loss and high step-down rectification is realized. ...

Li, Wei

283

Analysis of three-phase rectifiers with constant-voltage loads  

E-print Network

This work presents a quantitative analysis of the operating characteristics of three-phase diode bridge rectifiers with AC-side reactance and constant-voltage loads. We focus on the case where the AC-side currents vary ...

Caliskan, Vahe

284

Damping of a parallel ac-dc power system using PID power system stabilizers and rectifier current regulators  

SciTech Connect

A novel approach is presented to improve the dynamic stability of a parallel AC-DC power system. The developed scheme employs a proportional-integral-derivative (PID) power system stabilizer (PSS) and a PID rectifier current regulator (RCR) to enhance the damping for the electromagnetical mode of the system. The parameters of the proposed PID controllers are determined using a unified approach based on modal control theory. Eigenvalue analyses are performed for the system under various operating conditions in order to compare the damping effects provided by the two different control schemes. To demonstrate the effectiveness of the proposed damping schemes under disturbance conditions simulated dynamic response tests based on a nonlinear system model are also performed.

Hsu, Y.Y.; Wang, L. (Dept. of Electrical Engineering, National Taiwan Univ., Taipei (TW))

1988-09-01

285

Operation and test of hybridized silicon p-i-n arrays using open-source array control hardware and software  

NASA Astrophysics Data System (ADS)

A system for controlling and testing high-resolution non-destructive astronomical imagers was constructed using open-source components, both hardware and software. The open-source electronics design, originated by Carnegie Observatories (OCIW) for CCD cameras, was modified, assembled, and augmented with new circuitry which facilitates monitoring of voltages and currents. The electronics was run from Python user interface software based on a design from the University of Rochester. This new software utilized the Numarray and pyFITS modules developed at the Space Telescope Science Institute (STScI). Interfacing to the "dv" FITS image analysis package from the NASA IRTF was also implemented. Python (the STScI language of choice) was used as the primary language for systems integration, scripts for data acquisition, and scripts for data analysis. The DSP clocking software was a mixture of C and Motorola 56303 assembly. An interrupt-driven kernel-mode PCI device driver for Red Hat Linux was written in C, and used the PC processor and memory for image processing and acquisition. Two 1? 1? Raytheon SB226-based hybridized silicon p-i-n arrays were operated and tested with the new system at temperatures as low as 10K. Signal path gain, node capacitance, well depth, dark current, and MTF measurements were made and are presented here.

Moore, Andrew C.; Ninkov, Zoran; Burley, Gregory S.; Forrest, William J.; McMurtry, Craig W.; Avery, Lars E.

2003-05-01

286

DNA Physical Mapping via the Controlled Translocation of Single Molecules through a 5-10nm Silicon Nitride Nanopore  

NASA Astrophysics Data System (ADS)

The ability to map the binding position of sequence-specific markers, including transcription-factors, protein-nucleic acids (PNAs) or deactivated restriction enzymes, along a single DNA molecule in a nanofluidic device would be of key importance for the life-sciences. Such markers could give an indication of the active genes at particular stage in a cell's transcriptional cycle, pinpoint the location of mutations or even provide a DNA barcode that could aid in genomics applications. We have developed a setup consisting of a 5-10 nm nanopore in a 20nm thick silicon nitride film coupled to an optical tweezer setup. The translocation of DNA across the nanopore can be detected via blockades in the electrical current through the pore. By anchoring one end of the translocating DNA to an optically trapped microsphere, we hope to stretch out the molecule in the nanopore and control the translocation speed, enabling us to slowly scan across the genome and detect changes in the baseline current due to the presence of bound markers.

Stein, Derek; Reisner, Walter; Jiang, Zhijun; Hagerty, Nick; Wood, Charles; Chan, Jason

2009-03-01

287

Design and test of a 2.25-MW transformer rectifier assembly  

NASA Technical Reports Server (NTRS)

A new 2.25-MW transformer rectifier assembly was fabricated for DSS-13 at Goldstone, California. The transformer rectifier will provide constant output power of 2.25 MW at any voltage from 31 kV to 125 kV. This will give a new capability of 1 MW of RF power at X-band, provided appropriate microwave tubes are in the power amplifier. A description of the design and test results is presented.

Cormier, R.; Daeges, J.

1989-01-01

288

InAs=InGaP=GaAs heterojunction power Schottky rectifiers  

E-print Network

-beam epitaxy (MBE) technique led to a non-abrupt interface and leaky contact. Recently, a low-temperature (LTInAs=InGaP=GaAs heterojunction power Schottky rectifiers A. Chen, M. Young and J.M. Woodall A low-temperature-matched InGaP on GaAs, to make a high-temperature power rectifier. The LT molecular beam epitaxy technique

Woodall, Jerry M.

289

Electrostatic tuning of Mg2+ affinity in an inward-rectifier K+ channel  

Microsoft Academic Search

INWARD-RECTIFIER potassium channels conduct K+across the cell membrane more efficiently in the inward than outward direction. This unusual conduction property is directly related to the biological action of these channels1-6. One basis for inward rectification is voltage-dependent blockade by intracellular Mg2+ (refs 1, 7-9): strong inward-rectifier channels are so sensitive to intracellular Mg2+ that no outward K+ current is measurable

Zhe Lu; Roderick MacKinnon

1994-01-01

290

Analysis on Center-Tap Rectifier Voltage Oscillation of LLC Resonant Converter  

Microsoft Academic Search

The LLC resonant converter employing a center-tap rectifier can suffer from a high voltage oscillation across rectifier diodes owing to a leakage inductance of a transformer secondary. The amplitude of this voltage oscillation is varied according to design parameters, parasitic components, and operation regions, i.e., below-resonant region and above-resonant region. To reduce the diode voltage stress, this paper analyzes the

Ki-Bum Park; Byoung-Hee Lee; Gun-Woo Moon; Myung-Joong Youn

2012-01-01

291

Controlling Er-Tm interaction in Er and Tm codoped silicon-rich silicon oxide using nanometer-scale spatial separation for efficient, broadband infrared luminescence  

SciTech Connect

The effect of nanometer-scale spatial separation between Er{sup 3+} and Tm{sup 3+} ions in Er and Tm codoped silicon-rich silicon oxide (SRSO) films is investigated. Er and Tm codoped SRSO films, which consist of nanocluster Si (nc-Si) embedded inside SiO{sub 2} matrix, were fabricated with electron cyclotron resonance-plasma enhanced chemical vapor deposition of SiH{sub 4} and O{sub 2} with concurrent sputtering of Er and Tm metal targets. Spatial separation between Er{sup 3+} and Tm{sup 3+} ions was achieved by depositing alternating layers of Er- and Tm-doped layers of varying thickness while keeping the total film thickness the same. The films display broadband infrared photoluminescence (PL) from 1.5 to 2.0 {mu}m under a single source excitation due to simultaneous excitation of Er{sup 3+} and Tm{sup 3+} ions by nc-Si. Increasing the layer thickness from 0 to 72 nm increases the Er{sup 3+} PL intensity nearly 50-fold while the Tm{sup 3+} PL intensity is unaffected. The data are well-explained by a model assuming a dipole-dipole interaction between excited Er{sup 3+} and Tm{sup 3+} ions, and suggest that by nanoscale engineering, efficient, ultrabroadband infrared luminescence can be obtained in an optically homogeneous material using a single light source.

Seo, Se-Young; Shin, Jung H. [Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong-dong, Yuseong-gu, Daejon (Korea, Republic of)

2004-11-01

292

Remote electrical stimulation by means of implanted rectifiers.  

PubMed

Miniaturization of active implantable medical devices is currently compromised by the available means for electrically powering them. Most common energy supply techniques for implants--batteries and inductive couplers--comprise bulky parts which, in most cases, are significantly larger than the circuitry they feed. Here, for overcoming such miniaturization bottleneck in the case of implants for electrical stimulation, it is proposed to make those implants act as rectifiers of high frequency bursts supplied by remote electrodes. In this way, low frequency currents will be generated locally around the implant and these low frequency currents will perform stimulation of excitable tissues whereas the high frequency currents will cause only innocuous heating. The present study numerically demonstrates that low frequency currents capable of stimulation can be produced by a miniature device behaving as a diode when high frequency currents, neither capable of thermal damage nor of stimulation, flow through the tissue where the device is implanted. Moreover, experimental evidence is provided by an in vivo proof of concept model consisting of an anesthetized earthworm in which a commercial diode was implanted. With currently available microelectronic techniques, very thin stimulation capsules (diameter <500 m) deliverable by injection are easily conceivable. PMID:21850274

Ivorra, Antoni

2011-01-01

293

Reduction of burn scar formation by halofuginone-eluting silicone gel sheets: a controlled study on nude mice.  

PubMed

Burn scar formations can cause disfiguration and loss of dermal function. The purpose of this study was to examine whether application of modified silicone gel sheets with an antifibrotic drug halofuginone-eluting hybrid surface produce an effect on scar development. There were a total of 2 animal groups. The athymic nude mice (nu/nu) of both groups underwent transplantation of full-thickness human skin grafts onto their backs and setting of partial thickness burn injury. The status of local scar development was observed over a period of 3 months after the application of silicone gel sheets and also after application of surface-modified halofuginone-eluting silicone gel sheets. Subsequently, via real-time polymerase chain reaction, the cDNA levels from key mediators of scar formation (transforming growth factor beta, COL1A1, connective tissue growth factor, fibroblast growth factor 2, matrix metalloproteinase 2, matrix metalloproteinase 9) were established and statistically evaluated. In comparison with uncoated silicone gel sheets, the application of halofuginone-eluting silicone gel sheets lead to a significant difference in gene expression activity in scar tissue. Halofuginone-eluting hybrid surface silicone gel sheets significantly increase the antiscarring effect of adhesive silicone gel sheets by deceleration and downregulation of scar development by normalization of the expression activity. PMID:22356780

Zeplin, Philip H

2012-03-01

294

Controlled Compensation Walls and Compromise Compensation Walls in Garnet Films by the Silicon Annealing Technique  

Microsoft Academic Search

The Si annealing technique has been used on Ga-substituted LPE bubble garnet films to reduce 4piM through zero and produce controlled, well-defined compensation walls. A Si film was deposited on a garnet film, patterned photolithographically, and annealed at 525C for 40 hours in O2. This produced light and dark Faraday contrast regions separated by compensation walls which were independent of

R. C. Lecraw; R. Wolfe

1974-01-01

295

An idealized model of the one-dimensional carbon dioxide rectifier effect  

NASA Astrophysics Data System (ADS)

The net flux of carbon dioxide (CO2) from the land surface into the atmospheric boundary layer has a diurnal cycle. Drawdown of CO2 occurs during daytime photosynthesis, and return of CO2 to the atmosphere occurs during night. Even when the net diurnal-average surface flux vanishes, the diurnal-average profile of atmospheric CO2 mixing ratio is usually not vertically uniform. This is because of the diurnal rectifier effect, by which atmospheric vertical transport and the surface flux conspire to produce a surplus of CO2 near the ground and a deficit aloft. This paper constructs an idealized, 1-D, eddy-diffusivity model of the rectifier effect and provides an analytic series solution. When non-dimensionalized, the intensity of the rectifier effect is related solely to a single `rectifier parameter'. Given this model's governing equation and boundary conditions, we prove that the existence of the rectifier effect is related to the correlation of CO2 gradient and transport, and also to the day-night symmetry of transport. The rectifier-induced near-surface CO2 surplus ought to be included in inverse calculations that use near-surface CO2 mixing ratio to infer land-surface sources and sinks of carbon. Such inverse modeling is facilitated by our model's simplicity. To illustrate, we use a 1-D inverse calculation to infer the amplitude of diurnal CO2 surface flux.

Larson, Vincent E.; Volkmer, Hans

2008-09-01

296

A multi-level buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications  

Microsoft Academic Search

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multilevel diode rectifier and a multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier has a few

M. L. Zhang; B. Wu; Y. Xiao; F. Dewinter; R. Sotudeh

1999-01-01

297

A multilevel buck converter based rectifier with sinusoidal inputs and unity power factor for medium voltage (4160-7200 V) applications  

Microsoft Academic Search

A novel rectifier topology for high power (0.5 to 10 MVA) current source based AC motor drives is proposed. This rectifier is composed of a multi-winding transformer, a multi-level diode rectifier and a modified multi-level buck converter. The rectifier produces near unity input power factor and sinusoidal input current under any operating conditions. In addition, the proposed rectifier features reliable

Michael Lan Zhang; Bin Wu; Yuan Xiao; F. A. Dewinter; R. Sotudeh

2002-01-01

298

Automotive Power Generation and Control  

E-print Network

This paper describes some new developments in the application of power electronics to automotive power generation and control. A new load-matching technique is introduced that uses a simple switched-mode rectifier to achieve ...

Caliskan, Vahe

299

Commissioning of the control and data acquisition electronics for the CDF Silicon Vertex Detector  

SciTech Connect

The SVX data acquisition system includes three components: a Fastbus Sequencer, an SVX Rabbit Crate Controller and a Digitizer. These modules are integrated into the CDF DAQ system and operate the readout chips. The results of the extensive functional tests of the SVX modules are reported. We discuss the stability of the Sequencers, systematic differences between them and methods of synchronization with the Tevatron beam crossings. The Digitizer ADC calibration procedure run on the microsequencer is described. The microsequencer code used for data taking and SVX chip calibration modes is described. Measurements of the SVX data scan time are discussed.

Tkaczyk, S.M.; Turner, K.J.; Nelson, C.A.; Shaw, T.M.; Wesson, T.R. [Fermi National Accelerator Lab., Batavia, IL (United States); Bailey, M.W.; Kruse, M.C. [Purdue Univ., Lafayette, IN (United States); Castro, A. [Padua Univ. (Italy)

1991-11-01

300

Controllable shrinking and shaping of silicon nitride nanopores under electron irradiation  

SciTech Connect

Modification of the Si3N4 nanopore was investigated under electron beam (e-beam) irradiation using a scanning electron microscope (SEM) and the results show that all the pores with diameters ranging from 40-200 nm can be shrunk and reshaped. The shrinkage rate increases with the energy deposited in the membrane. By using the selected area scan tool in the SEM, different shapes of Si3N4 nanopores have been fabricated successfully based on localized e-beam-induced joule heat, with characteristic dimension smaller than 10 nm. A novel technique was proposed to shrink and shape the nanopore to a special structure controllably.

Zhang, Weiming; Wang, Yugang; Li, Juan; Xue, Jianming; Ji, Hang; Ouyang, Qi; Xu, Jun; Zhang, Yanwen

2007-04-16

301

Orientation- and position-controlled alignment of asymmetric silicon microrod on a substrate with asymmetric electrodes  

NASA Astrophysics Data System (ADS)

In this paper, we demonstrate the orientation-controlled alignment of asymmetric Si microrods on a glass substrate with an asymmetric pair of electrodes. The Si microrods have the shape of a paddle with a blade and a shaft part, and the pair of electrodes consists of a narrow electrode and a wide electrode. By applying AC bias to the electrodes, the Si microrods suspended in a fluid align in such a way to settle across the electrode pair, and over 80% of the aligned Si microrods have an orientation with the blade and the shaft of the paddle on the wide and the narrow electrodes, respectively. When Si microrods have a shell of dielectric film and its thickness on the top face is thicker than that on the bottom face, 97.8% of the Si microrods are aligned with the top face facing upwards. This technique is useful for orientation-controlled alignment of nano- and microsized devices that have polarity or a distinction between the top and bottom faces.

Shibata, Akihide; Watanabe, Keiji; Sato, Takuya; Kotaki, Hiroshi; Schuele, Paul J.; Crowder, Mark A.; Zhan, Changqing; Hartzell, John W.; Nakatani, Ryoichi

2014-03-01

302

Polycrystalline silicon availability for photovoltaic and semiconductor industries  

NASA Technical Reports Server (NTRS)

Markets, applications, and production techniques for Siemens process-produced polycrystalline silicon are surveyed. It is noted that as of 1982 a total of six Si materials suppliers were servicing a worldwide total of over 1000 manufacturers of Si-based devices. Besides solar cells, the Si wafers are employed for thyristors, rectifiers, bipolar power transistors, and discrete components for control systems. An estimated 3890 metric tons of semiconductor-grade polycrystalline Si will be used in 1982, and 6200 metric tons by 1985. Although the amount is expected to nearly triple between 1982-89, research is being carried out on the formation of thin films and ribbons for solar cells, thereby eliminating the waste produced in slicing Czolchralski-grown crystals. The free-world Si production in 1982 is estimated to be 3050 metric tons. Various new technologies for the formation of polycrystalline Si at lower costs and with less waste are considered. New entries into the industrial Si formation field are projected to produce a 2000 metric ton excess by 1988.

Ferber, R. R.; Costogue, E. N.; Pellin, R.

1982-01-01

303

Mechanism of inhibition of delayed rectifier K+ current by 4-aminopyridine in rabbit coronary myocytes.  

PubMed Central

1. The mechanisms involved in the 4-aminopyridine (4-AP)-induced block of delayed rectifier K+ current (IK(V)) in vascular smooth muscle cells were studied in cells enzymatically isolated from the rabbit coronary artery. 2. 4-AP inhibited slowly inactivating IK(V) in a dose-dependent manner (concentration producing half-maximal inhibition, K1/2, = 1.37 mM), and shifted the steady-state activation and inactivation curves of IK(V) by +9 and +16 mV, respectively. 3. The time constant of activation was significantly increased by 4-AP at +20 mV; deactivation kinetics were unaffected upon repolarization to -40 mV. The fast (tau f approximately 1 s) and slow (tau s approximately 5 s) time constants of inactivation (0 and +20 mV), and the recovery kinetics (tau r approximately 6 s) at -60 mV were not significantly affected by 0.5 mM 4-AP. However, tau f disappeared in the presence of 2 mM 4-AP while tau s remained unaffected. 4. Use-dependent unblock of IK(V) was revealed at potentials > or = -10 mV from analyses of the voltage dependence of 4-AP-sensitive currents and the frequency-dependent changes ('reverse use dependence') of IK(V) during the application of repetitive steps (-60 to +20 mV for 250 ms at a rate of 0.25 Hz) in control conditions, in the presence of 0.5 mM 4-AP, and after washout of the drug. These results suggested that 4-AP preferentially binds to the channel in the closed state, and unbinding is promoted by transitions to the open state. 5. The channel was modelled as a simple three-state mathematical loop model incorporating single closed, open and inactivated states. The block by 4-AP was modelled as a state-dependent interaction with 4-AP primarily binding to the closed state. Computer simulations support the hypothesis that 4-AP-induced block of the delayed rectifier K+ (KV) channel in the closed state is relieved during membrane depolarization. 6. Closed state binding of 4-AP to the KV channel depolarizes vascular smooth muscle cells by shifting the activation curve of these channels to more positive potentials. PMID:8866862

Remillard, C V; Leblanc, N

1996-01-01

304

Gate Tunable Graphene-Silicon Ohmic/Schottky Contact  

NASA Astrophysics Data System (ADS)

We have recently demonstrated gate tunable graphene-silicon Schottky diodes, in which the low bias conductance can be varied by more than three orders of magnitude [1,2]. Here, we deposit graphene on silicon substrates and observe the rectifying I-V characteristics in graphene-silicon junctions, indicating the formation of Schottky junction due to the mismatch of their work functions. By applying a polymer electrolyte gate to the graphene surface, the Fermi energy of the graphene can be shifted 0.85eV from its charge neutrality point (-4.6eV) to match the conduction (-4.01eV ) or valence band (-5.13eV) of silicon to reduce the Schottky barrier and result in Ohmic contacts with both n- and p-type silicon. The I-V characteristics observed under light illumination also indicate that the short circuit current can be increased or decreased by varying graphene-silicon work function difference, further demonstrating that the graphene-silicon junction and be changed between Schottky and Ohmic contact. [4pt] [1] Chen, Aykol, Chang, Levi, and Cronin, ``Graphene-Silicon Schottky Diodes.'' Nano Letters, 11, 1863-1867 (2011).[0pt] [2] Chen, Chang, Li, Levi, Cronin, ``Gate Tunable Graphene-Silicon Ohmic/Schottky Contacts.'' Applied Physics Letters, accepted (2012).

Chung Chen, Chun; Chang, Chia Chi; Li, Zhen; Levi, Anthony; Cronin, Steve

2013-03-01

305

High-power 4H-SiC JBS rectifiers  

Microsoft Academic Search

This paper reports the detailed design, fabrication, and characterization of two sets of high-power 4H-silicon carbide (4H-SiC) junction barrier Schottky (JBS) diodes - one with a 1500-V, 4-A capability and another with 1410-V, 20-A capability. Two-dimensional (2-D) device simulations show that a grid spacing of 4 ?m results in the most optimum trade-off between the on-state and off-state characteristics for

Ranbir Singh; D. Craig Capell; Allen R. Hefner; Jason Lai; John W. Palmour

2002-01-01

306

Surprise signals in the supplementary eye field: rectified prediction errors drive exploration-exploitation transitions.  

PubMed

Visual search is coordinated adaptively by monitoring and predicting the environment. The supplementary eye field (SEF) plays a role in oculomotor control and outcome evaluation. However, it is not clear whether the SEF is involved in adjusting behavioral modes based on preceding feedback. We hypothesized that the SEF drives exploration-exploitation transitions by generating "surprise signals" or rectified prediction errors, which reflect differences between predicted and actual outcomes. To test this hypothesis, we introduced an oculomotor two-target search task in which monkeys were required to find two valid targets among four identical stimuli. After they detected the valid targets, they exploited their knowledge of target locations to obtain a reward by choosing the two valid targets alternately. Behavioral analysis revealed two distinct types of oculomotor search patterns: exploration and exploitation. We found that two types of SEF neurons represented the surprise signals. The error-surprise neurons showed enhanced activity when the monkey received the first error feedback after the target pair change, and this activity was followed by an exploratory oculomotor search pattern. The correct-surprise neurons showed enhanced activity when the monkey received the first correct feedback after an error trial, and this increased activity was followed by an exploitative, fixed-type search pattern. Our findings suggest that error-surprise neurons are involved in the transition from exploitation to exploration and that correct-surprise neurons are involved in the transition from exploration to exploitation. PMID:25411455

Kawaguchi, Norihiko; Sakamoto, Kazuhiro; Saito, Naohiro; Furusawa, Yoshito; Tanji, Jun; Aoki, Masashi; Mushiake, Hajime

2015-02-01

307

Characterization and properties of controlled nucleation thermochemical deposited (CNTD) silicon carbide  

NASA Technical Reports Server (NTRS)

The microstructure of controlled nucleation thermochemical deposition (CNTD) - SiC material was studied and the room temperature and high temperature bend strength and oxidation resistance was evaluated. Utilizing the CNTD process, ultrafine grained (0.01-0.1 mm) SiC was deposited on W - wires (0.5 mm diameter by 20 cm long) as substrates. The deposited SiC rods had superior surface smoothness and were without any macrocolumnar growth commonly found in conventional CVD material. At both room and high temperature (1200 - 1380 C), the CNTD - SiC exhibited bend strength approximately 200,000 psi (1380 MPa), several times higher than that of hot pressed, sintered, or CVD SiC. The excellent retention of strength at high temperature was attributed to the high purity and fine grain size of the SiC deposit and the apparent absence of grain growth at elevated temperatures. The rates of weight change for CNTD - SiC during oxidation were lower than for NC-203 (hot pressed SiC), higher than for GE's CVD - SiC, and considerably below those for HS-130 (hot pressed Si3N4). The high purity, fully dense, and stable grain size CNTD - SiC material shows potential for high temperature structural applications; however problem areas might include: scaling the process to make larger parts, deposition on removable substrates, and the possible residual tensile stress.

Dutta, S.; Rice, R. W.; Graham, H. C.; Mendiratta, M. C.

1978-01-01

308

D0 Silicon Upgrade: Control Dewar Venturi Calibration Explanation for Toshiba  

SciTech Connect

This document is intended to explain the calibration data for the venturi, FE-3253H, which is installed in the control dewar. Further, this document will help explain how to use the venturi to make mass flow measurements during typical operating conditions. The purpose of the calibration data enclosed from the Colorado Engineering Experiment Station Inc. is to experimentally show that the venturi follows the flow equation which is enclosed as Eq. 7-36 on page 155, from the Applied Fluid Dynamics Handbook. The calibration data serves to show that the Subsonic Venturi, Serial Number 611980-18, produces results predicted by the compressible subsonic flow mass flow rate equation above and to experimentally determine the discharge coefficient C. Colorado Engineering Experiment Station Inc. ran tests at 15 independent differential pressures to conclude that use of this venturi will perform according to the mass flow rate equation. In order to verify the results from the Colorado Engineering Experiment Station Inc. we have provided you with a step-by-step procedure using the values they have chosen.

Kuwazaki, Andrew; /Fermilab

1997-01-24

309

Deep Reactive Ion Etch (DRIE) Control for High-Aspect Ratio Silicon Structures  

NASA Astrophysics Data System (ADS)

Deep reactive ion etching (DRIE) of Si, also referred to as the Bosch process, has opened new areas of application in microelectromechanical systems (MEMS) and mixed technology integration. A fully integrated microsystem could include biological or chemical sensors, mechanical gears and actuators, control electronics, micro-fluidics, and optics in a variety of material systems on a single chip or in a single package. As the device designs become more complicated or monolithic integration becomes necessary, the requirements for DRIE of Si become more difficult. For example, anisotropic etch profiles, smooth etch morphology, high etch selectivity to form freestanding membrane structures, and the fabrication of multi-level etched features becomes critical to device performance. The DRIE process relies on the formation of a sidewall etch inhibitor to prevent lateral etching of the Si thus resulting in highly anisotropic etch profiles at reasonably high etch rates. In this presentation we will report on the use of the DRIE platform to fabricate deep, high-aspect ratio Si features 100 microns wide, 400 microns deep with 25 microns walls. Optimization of the DRIE process by varying process parameters including reactive gas flow, pressure, and ion energy will be discussed. The use of parameter ramping as well as multi-level masking processes to meet the challenges of advanced micro-sensor designs will also be discussed. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Shul, Randy

2003-10-01

310

Composition Comprising Silicon Carbide  

NASA Technical Reports Server (NTRS)

A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy L. (Inventor)

2012-01-01

311

Silicon Baroreceptors: Modeling Cardiovascular  

E-print Network

Silicon Baroreceptors: Modeling Cardiovascular Pressure Transduction in Analog VLSI John Lazzaro pressure used in a neural control system in the cardiovascular system. The chip computes the representation as a first step to understanding the neural computation of cardiovascular control; we hope to apply

Lazzaro, John

312

[The impact of silicone spray on scar formation. A single-center placebo-controlled double-blind trial].  

PubMed

For more than two decades silicone has successfully been employed in the treatment and prevention of hypertrophic scars and keloids as a painless noninvasive modality with few side effects. In the present trial, after 3 months of treatment the Patient Scar Assessment Scale demonstrated that patient satisfaction with the silicone application was significantly higher compared to placebo. When treatment was stopped after 3 months, the topical silicone spray did not exhibit any lasting long-term impact on the objective results of scar formation. Due to the significant differences in patient satisfaction once treatment has ended and since the administration is safe and simple, any final decision on treatment indication should be tailored to the patient and include the psychological well-being of the patient as well as the temporary improvement in scar formation during treatment. PMID:19967328

Stoffels, I; Wolter, T P; Sailer, A M; Pallua, N

2010-04-01

313

Enantioselective Protein-Sterol Interactions Mediate Regulation of Both Prokaryotic and Eukaryotic Inward Rectifier K+ Channels by Cholesterol  

PubMed Central

Cholesterol is the major sterol component of all mammalian cell plasma membranes and plays a critical role in cell function and growth. Previous studies have shown that cholesterol inhibits inward rectifier K+ (Kir) channels, but have not distinguished whether this is due directly to protein-sterol interactions or indirectly to changes in the physical properties of the lipid bilayer. Using purified bacterial and eukaryotic Kir channels reconstituted into liposomes of controlled lipid composition, we demonstrate by 86Rb+ influx assays that bacterial Kir channels (KirBac1.1 and KirBac3.1) and human Kir2.1 are all inhibited by cholesterol, most likely by locking the channels into prolonged closed states, whereas the enantiomer, ent-cholesterol, does not inhibit these channels. These data indicate that cholesterol regulates Kir channels through direct protein-sterol interactions likely taking advantage of an evolutionarily conserved binding pocket. PMID:21559361

D'Avanzo, Nazzareno; Hyrc, Krzysztof; Enkvetchakul, Decha; Covey, Douglas F.; Nichols, Colin G.

2011-01-01

314

Direct Production of Silicones From Sand  

SciTech Connect

Silicon, in the form of silica and silicates, is the second most abundant element in the earth's crust. However the synthesis of silicones (scheme 1) and almost all organosilicon chemistry is only accessible through elemental silicon. Silicon dioxide (sand or quartz) is converted to chemical-grade elemental silicon in an energy intensive reduction process, a result of the exceptional thermodynamic stability of silica. Then, the silicon is reacted with methyl chloride to give a mixture of methylchlorosilanes catalyzed by cooper containing a variety of tract metals such as tin, zinc etc. The so-called direct process was first discovered at GE in 1940. The methylchlorosilanes are distilled to purify and separate the major reaction components, the most important of which is dimethyldichlorosilane. Polymerization of dimethyldichlorosilane by controlled hydrolysis results in the formation of silicone polymers. Worldwide, the silicones industry produces about 1.3 billion pounds of the basic silicon polymer, polydimethylsiloxane.

Larry N. Lewis; F.J. Schattenmann: J.P. Lemmon

2001-09-30

315

Silicon based organic semiconductor laser  

NASA Astrophysics Data System (ADS)

The authors demonstrate silicon based visible lasers as potential optical interconnects by combining silicon processed resonators and solution processed light-emitting polymers. The high refractive index and absorption coefficient of silicon at these wavelengths were addressed by developing distributed Bragg reflector resonators on a silicon-on-insulator substrate. The performance of the hybrid structure was characterized and analyzed in comparison to an all-silica counterpart and mechanisms for controlling the number of longitudinal modes and for tuning the emission wavelength were explored.

Vasdekis, A. E.; Moore, S. A.; Ruseckas, A.; Krauss, T. F.; Samuel, I. D. W.; Turnbull, G. A.

2007-07-01

316

Rectifying Properties of Oligo(Phenylene Ethynylene) Heterometallic Molecular Junctions: Molecular Length and Side Group Effects  

NASA Astrophysics Data System (ADS)

The rectifying properties of ?,?-dithiol terminated oligo(phenylene ethynylene) molecules sandwiched between heterometallic electrodes, including the molecular length and side group effects, are theoretically investigated using the fully self-consistent nonequilibrium Green's function method combined with density functional theory. The results show nonlinear variation with changes in molecule length: when the molecule becomes longer, the current decreases at first and then increases while the rectification shifts in the opposite direction. This stems from the change in molecular eigenstates and the coupling between the molecule and electrodes caused by different molecular lengths. The rectifying behavior of heterometallic molecular junctions can be attributed to the asymmetric molecule-electrode contacts, which lead to asymmetric electronic tunneling spectra, molecular eigenvalues, molecular orbitals, and potential drop at reversed equivalent bias voltages. Our results provide a fundamental understanding of the rectification of heterometallic molecular junction, and a prediction of rectifiers with different rectification properties from those in the experiment, using electrodes with reduced sizes.

Fu, Xiao-Xiao; Zhang, Rui-Qin; Zhang, Guang-Ping; Li, Zong-Liang

2014-09-01

317

Controlling the delay of 100 Gb\\/s polarization division multiplexed signals through silicon photonics delay lines  

Microsoft Academic Search

We show a direct comparison between silicon reconfigurable delay lines based on coupled resonator optical waveguides and photonic crystal waveguides. The structures are used to selectively delay the two orthogonally polarized channels of a RZ-PolDM-DQPSK format at 100 Gbit\\/s.

F. Morichetti; A. Canciamilla; C. Ferrari; M. Torregiani; M. Ferrario; R. Siano; P. Boffi; L. Marazzi; P. Martelli; P. Parolari; M. Martinelli; A. Samarelli; M. Sorel; R. M. De La Rue; L. O'Faolain; D. M. Beggs; T. F. Krauss; A. Melloni

2010-01-01

318

A novel inward-rectifying K+ current with a cell-cycle dependence governs the resting potential of mammalian neuroblastoma cells.  

PubMed Central

1. Human and murine neuroblastoma cell lines were used to investigate, by the whole-cell patch-clamp technique, the properties of a novel inward-rectifying K+ current (IIR) in the adjustment of cell resting potential (Vrest), which was in the range -40 to -20 mV. 2. When elicited from a holding potential of 0 mV, IIR was completely inactivated with time constants ranging from 13 ms at -140 mV to 4.5 s at -50 mV. The steady-state inactivation curve (h(V)) was found to be independent of [Na+]o and [K+]o (2-80 mM) and could be fitted to a Boltzmann curve with a steep slope factor of 5-6, and a V1/2 around Vrest. Divalent ion-free extracellular solutions shifted h(V) to the left by about 28 mV. 3. Peak chord conductance, whose maximal value was approximately proportional to the square root of [K+]o, could be fitted to a Boltzmann curve independently of [K+]o, with a V1/2 value around -48 mV and a slope factor of 18. Extracellular Cs+ and Ba2+ blocked the IIR in a concentration- and voltage-dependent manner, but Ba2+ was less effective than it is on classical inward-rectifier channels. 4. Under control culture conditions the values of Vrest and V1/2 of h(V) varied widely among cells. The knowledge of V1/2 proved crucial or the theoretical prediction of Vrest. After cell synchronization in the G0-G1 phase of the cell cycle, or at the G1-S boundaries, the cells reduced their variability of h(V). The same occurred after cell synchronization in G1 by treatment with retinoic acid. 5. The experimental data could be fitted to a classical model of an inward rectifier, after removing the dependence of conductance activation on (V-EK), and incorporating an inactivation with an intrinsic voltage dependence. Moreover, the model predicts, for this novel inward rectifier and in contrast with the classical inward rectifier, the incapacity of maintaining, in physiological media, a Vrest more negative than -35 to -40 mV, which is an important feature of cancer cells. PMID:8847640

Arcangeli, A; Bianchi, L; Becchetti, A; Faravelli, L; Coronnello, M; Mini, E; Olivotto, M; Wanke, E

1995-01-01

319

Transport of particles and microorganisms in microfluidic channels using rectified ac electro-osmotic flow  

PubMed Central

A new method is demonstrated to transport particles, cells, and other microorganisms using rectified ac electro-osmotic flows in open microchannels. The rectified flow is obtained by synchronous zeta potential modulation with the driving potential in the microchannel. Experiments were conducted to transport both neutral, charged particles, and microorganisms of various sizes. A maximum speed of 50 ?m?s was obtained for 8 ?m polystyrene beads, without any electrolysis, using a symmetrical square waveform driving electric field of 5 V?mm at 10 Hz and a 360 V gate potential with its polarity synchronized with the driving potential (phase lag=0). PMID:21522497

Wu, Wen-I; Selvaganapathy, P. Ravi; Ching, Chan Y.

2011-01-01

320

Temperature dependence of GaN high breakdown voltage diode rectifiers  

NASA Astrophysics Data System (ADS)

The temperature dependence of reverse breakdown voltage ( VRB) and forward turn-on voltage ( VF) of GaN Schottky diode rectifiers is reported. The VRB values display a negative temperature coefficient (-0.92 V K -1 for 25-50C; -0.17 V K -1 for 50-150C), indicative of surface- or defect-assisted breakdown. The VF values decrease with increasing temperature. The room temperature breakdown voltage is approximately a factor of three lower than the theoretical maximum expected based on avalanche breakdown, and the current performance of GaN rectifiers is comparable to that of Si at the same on-resistance.

Chyi, J.-I.; Lee, C.-M.; Chuo, C.-C.; Cao, X. A.; Dang, G. T.; Zhang, A. P.; Ren, F.; Pearton, S. J.; Chu, S. N. G.; Wilson, R. G.

2000-04-01

321

Maxwell's demon, rectifiers, and the second law: Computer simulation of Smoluchowski's trapdoor  

SciTech Connect

An automated version of Maxwell's demon inspired by Smoluchowski's ideas of 1912 is simulated numerically. Two gas chambers of equal volume are connected via an opening that is covered by a trapdoor. The trapdoor can open to the left but not to the right, and is intended to rectify naturally occurring fluctuations in density between the two chambers. The simulation results confirm that though the trapdoor behaves as a rectifier when large density differences are imposed by external means, it cannot extract useful work from the thermal motion of the molecules when left on its own.

Skordos, P.A. (Santa Fe Institute, Santa Fe (New Mexico, United States) Massachusetts Institute of Technology, 545 Technology Square, Cambridge, Massachusetts 02139 (United States)); Zurek, W.H. (Theoretical Division, T-6, MS B288, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States) Santa Fe Institute, Santa Fe (New Mexico, United States))

1992-10-01

322

A Robust Silicon-on-Insulator Static-Random-Access-Memory Architecture by using Advanced Actively Body-Bias Controlled Technology  

NASA Astrophysics Data System (ADS)

This paper presents that advanced actively body-bias controlled (Advanced ABC) technology contributes to enhancing operation margins of static random access memory (SRAM). For the first time, significant enhancement of static noise margin (SNM) is successfully realized by using a body bias of load, access, and driver transistors while suppressing threshold-voltage variations. In this technology, well taps control the body potential of the load transistor and word lines also control the body potential of the access and driver transistors. It is demonstrated that the write and read margins of 65-nm-node silicon-on-insulator (SOI) SRAMs are improved by the Advanced ABC technology. Furthermore, it is found that the SNM is enhanced by 27% for 32 nm and 49% for 22 nm node. It is summarized that this technology is one of countermeasures for emerging generations.

Hirano, Yuuichi; Tsujiuchi, Mikio; Ishikawa, Kozo; Shinohara, Hirofumi; Terada, Takashi; Maki, Yukio; Iwamatsu, Toshiaki; Eikyu, Katsumi; Uchida, Tetsuya; Obayashi, Shigeki; Nii, Koji; Tsukamoto, Yasumasa; Yabuuchi, Makoto; Ipposhi, Takashi; Oda, Hidekazu; Inoue, Yasuo

2008-04-01

323

High efficiency current-doubler rectifier with low output current ripple and high step-down voltage ratio  

Microsoft Academic Search

This paper presents a current-doubler rectifier with low output current ripple and high step-down voltage ratio. In the proposed rectifier, two extra inductors are introduced to extend the duty ratio of switches which in turn can reduce the peak current through the isolation transformer and lower output current ripple, and two extra diodes are used to provide discharge paths for

Chih-Lung Shen; Cheng-Tao Tsai; Yu-En Wu

2008-01-01

324

HIGH EFFICIENCY 3-PHASE CMOS RECTIFIER WITH STEP UP AND REGULATED OUTPUT VOLTAGE -DESIGN AND SYSTEM ISSUES FOR MICRO GENERATION  

E-print Network

HIGH EFFICIENCY 3-PHASE CMOS RECTIFIER WITH STEP UP AND REGULATED OUTPUT VOLTAGE - DESIGN related to the monolithic integration of a 3-phase AC to DC low voltage, low power rectifier for 3-phase micro source electrical conditioning. Reduced input voltage operation (down to 1V), high efficiency

Paris-Sud XI, Université de

325

Seventeen years of the ``La Clapie`re'' landslide evolution analysed from ortho-rectified aerial photographs  

E-print Network

Seventeen years of the ``La Clapie`re'' landslide evolution analysed from ortho-rectified aerial this method to the La Clapie`re landslide in the Mercantour Massif in eastern France. The method uses new these ortho-rectified images, show that the average velocity of the landslide was of 1.7 cm/day, with the rate

Delacourt, Christophe

326

Morphology control of gallium nitride grown on silicon nanoporous pillar array: From cone-strings to nanowires  

NASA Astrophysics Data System (ADS)

Fascicle arrays of gallium nitride (GaN) nanostructures were grown on silicon nanoporous pillar array (Si-NPA) by a reactive chemical vapor deposition method. Through adjusting the distance between the gallium source and Si-NPA substrate, the morphology of GaN nanostructures was tuned from cone-strings, cone-strings plus nanowires to nanowires, accompanied with the average diameter changed from 800 nm to 13 nm. Both the cone-strings and the nanowires were found growing along [0001] direction. These results indicate that Ga concentration is a key factor in determining both the morphology and the average diameter of GaN nanostructures. The growing process of the GaN nanostructures was explained under the frame of vapor-liquid-solid deposition mechanism. Our method might be expanded to the growth of other compound semiconductor nanostructures on patterned silicon substrates for constructing functional nanodevices.

Han, Chang Bao; He, Chuan; Li, Xin Jian

2012-07-01

327

An asymmetrical half-bridge active DC filter for industrial drive systems using multipulse utility rectifiers with harmonic reducing input transformers  

Microsoft Academic Search

The operation of parallel-connected multi-pulse 3-phase rectifiers are described that use isolating and also non-isolating multi-winding input transformers. The performance of these rectifiers are analysed with unbalanced transformer output voltages and inductances. The rectifier operation is more sensitive to these imbalances the larger the number of parallel bridges used. Auto-transformers require inter-phase blocking reactors to balance the rectifier input currents.

John Salmon; Mihaela Ciulei

2003-01-01

328

Controlled grafting of well-defined epoxide polymers on hydrogen-terminated silicon substrates by surface-initiated ATRP at ambient temperature.  

PubMed

Controlled grafting of well-defined epoxide polymer brushes on the hydrogen-terminated Si(100) substrates (Si-H substrates) was carried out via the surface-initiated atom-transfer radical polymerization (ATRP) at room temperature. Thus, glycidyl methacrylate (GMA) polymer brushes were prepared by ATRP from the alpha-bromoester functionalized Si-H surface. Kinetic studies revealed a linear increase in GMA polymer (PGMA) film thickness with reaction time, indicating that chain growth from the surface was a controlled "living" process. The graft polymerization proceeded more rapidly in the dimethylformamide/water (DMF/H(2)O) mixed solvent medium than in DMF, leading to much thicker PGMA growth on the silicon surface in the former medium. The chemical composition of the GMA graft-polymerized silicon (Si-g-PGMA) surfaces were characterized by X-ray photoelectron spectroscopy (XPS). The fact that the epoxide functional groups of the grafted PGMA were preserved quantitatively was revealed in the reaction with ethylenediamine. The "living" character of the PGMA chain end was further ascertained by the subsequent growth of a poly(pentafluorostyrene) (PFS) block from the Si-g-PGMA surface, using the PGMA brushes as the macroinitiators. PMID:15350105

Yu, W H; Kang, E T; Neoh, K G

2004-09-14

329

Diffusion-controlled growth of hydrogen pores in aluminum-silicon castings: In situ observation and modeling  

Microsoft Academic Search

In situ observations were made of the nucleation and growth kinetics of hydrogen porosity during the directional solidification of aluminium-7 wt% silicon (Al7Si) with TiB grain refiner added, using an X-ray temperature gradient stage (XTGS). The effect of altering the solidification velocity on the growth rate and morphology of the porosity formed was characterized by tracking individual pores with digital

R. C. Atwood; S. Sridhar; W. Zhang; P. D. Lee

2000-01-01

330

Diffusion-controlled growth of hydrogen pores in aluminiumsilicon castings: in situ observation and modelling  

Microsoft Academic Search

In situ observations were made of the nucleation and growth kinetics of hydrogen porosity during the directional solidification of aluminium7wt% silicon (Al7Si) with TiB2 grain refiner added, using an X-ray temperature gradient stage (XTGS). The effect of altering the solidification velocity on the growth rate and morphology of the porosity formed was characterized by tracking individual pores with digital analysis

R. C. Atwood; S. Sridhar; W. Zhang; P. D. Lee

2000-01-01

331

Elastic strain sharing in silicon\\/silicon germanium nanomembranes  

Microsoft Academic Search

Controlling strain in the silicon\\/silicon-germanium hetero-system provides control over band offsets and carrier mobility. The main problem in the Si\\/SiGe system is that to obtain strained Si layers, SiGe relaxation, typically by dislocation motion, is required. Dislocations extending into the device layer degrade device performance. This dissertation describes a new method of creating large-area, continuous, strained-Si films with no or

Michelle M. Kelly

2007-01-01

332

Bacterial endogenous endophthalmitis in Vietnam: a randomized controlled trial comparing vitrectomy with silicone oil versus vitrectomy alone  

PubMed Central

Background/aims To compare treatment outcomes with and without silicone oil tamponade in patients undergoing pars plana vitrectomy (PPV) for severe endogenous bacterial endophthalmitis (BEE). Methods One hundred and eight consecutive patients with severe BEE (defined by the absence of pupil red reflex at presentation and/or dense vitreous opacity on ultrasound and no improvement after 2436 hours of medical treatment) were randomly assigned to two treatment groups: Group 1, standard PPV with intravitreal antibiotics; and Group 2, PPV with intravitreal antibiotics and silicone tamponade. Overall success was defined as: a visual acuity ? count fingers at 1 meter, with an attached retina, and no intraocular oil. Results Fifty three patients were randomized to Group 1 and 55 patients to Group 2. The mean age of study subjects was 32 years and baseline clinical characteristics were similar in both groups. At the final follow-up visit at 9 months, the overall success rate of Group 2 (67.3%) was significantly better than Group 1 (43.4%; P=0.01). There were also fewer devastating complications (such as inoperable retinal detachment, phthisis bulbi) in Group 2 compared with Group 1 (21.8% versus 43.4%; P=0.01). Conclusion The outcome at 9 months of patients with BEE treated by vitrectomy with silicone oil was better than those treated by vitrectomy alone. PMID:25210432

Do, Tan; Hon, Do N; Aung, Tin; Hien, Nguyen DTN; Cowan, Claude L

2014-01-01

333

A Microfluidic Rectifier: Anisotropic Flow Resistance at Low Reynolds Numbers Alex Groisman* and Stephen R. Quake  

E-print Network

A Microfluidic Rectifier: Anisotropic Flow Resistance at Low Reynolds Numbers Alex Groisman of Newtonian fluid dynamics that at low Reynolds number (Re) the Navier-Stokes equation is linear and flows are reversible. In microfluidic devices, where Re is essentially always low, this implies that flow resistance

Quake, Stephen R.

334

Ballistic Rectifiers Z. Bennett, M. Koyama, T. Hayafuji, S. Sasa, T. Maemoto, M. Inoue  

E-print Network

. Then the device is outlined using electron- beam lithography, and then formed with wet chemical etching, and big electrodes are created using photo lithography. These are used to access the device electrically of ballistic rectifiers The darker area was etched by E-beam Lithography Instead of a pool table, we have a 2

335

A fast dynamic phasor model of autotransformer rectifier unit for more electric aircraft  

Microsoft Academic Search

This paper presents a dynamic phasor model of the autotransformer rectifier unit (ATRU) for the more-electric aircraft power system study. This model considerably reduces the complexity in modeling of an aircraft power system making it more practical to model the electrical power system for transient and stability analysis. The developed phasor model of the ATRU is based on the development

T. Wu; S. V. Bozhko; G. M. Asher; D. W. P. Thomas

2009-01-01

336

Self-Rectifying Effect in Resistive Switching Memory Using Amorphous InGaZnO  

NASA Astrophysics Data System (ADS)

Resistance random access memory (ReRAM) has received attention as next-generation memory because of its excellent operating properties and high density integration capability as a crossbar array. However, the application of the existing ReRAM as a crossbar array may lead to crosstalk between adjacent cells due to its symmetric I- V characteristics. In this study, the self-rectifying effect of contact between amorphous In-Ga-Zn-O (a-IGZO) and TaO x was examined in a Pt/a-IGZO/TaO x /Al2O3/W structure. The experimental results show not only self-rectifying behavior but also forming-free characteristics. During the deposition of a-IGZO on the TaO x , an oxygen-rich TaO x interfacial layer was formed. The rectifying effect was observed regardless of the interface formation and is believed to be associated with Schottky contact formation between a-IGZO and TaO x . The current level remained unchanged despite repeated DC sweep cycles. The low resistance state/high resistance state ratio was about 101 at a read voltage of -0.5 V, and the rectifying ratio was about 103 at 2 V.

Lee, Jin-Woo; Kwon, Hyeon-Min; Kim, Myeong-Ho; Lee, Seung-Ryul; Kim, Young-Bae; Choi, Duck-Kyun

2014-05-01

337

Phase-Rectified Signal Averaging to Evaluate ANS Development in Premature Infants  

E-print Network

-Rectified Signal Averaging, Heart Rate Variability, Autonomic Nervous System, Quasi-Periodicities, Non-Stationary Signals. Abstract: Aim: Heart Rate Variability (HRV) is determined by the autonomic nervous system (ANS: breathing, hormones, the autonomic nervous system (ANS), etc. The parasympathetic nervous system has

338

Analysis and design of LLC resonant converter considering rectifier voltage oscillation  

Microsoft Academic Search

The LLC resonant converter employing the center-tap rectifier can suffer from high voltage oscillation across the secondary diodes owing to the transformer secondary leakage inductance. The amplitude of the voltage oscillation is varied according to the operation region, i.e., below resonant region and above resonant region. To reduce the diode voltage stress without snubbers, this paper analyzes the voltage oscillation

Ki-Bum Park; Bong-Chul Kim; Byoung-Hee Lee; Chong-Eun Kim; Gun-Woo Moon; Myung-Joong Youn

2009-01-01

339

Design of high power density DC Bus Converter based on LLC resonant converter with synchronous rectifier  

Microsoft Academic Search

The LLC resonant converter can easily achieve soft-switching and magnetic components integration that makes it an excellent candidate for DC bus converter. In low voltage high output current applications, the design of synchronous rectifier (SR) and transformer is the key issue. A SR driving scheme with less circuit complexity is adopted for switching frequency at the resonant frequency in this

Niu Huapeng; Pei Yunqing; Yang Xu; Wang Laili; Wang Zhaoan

2009-01-01

340

An improved novel driving scheme of synchronous rectifiers for LLC resonant converters  

Microsoft Academic Search

This paper proposes an improved novel synchronous rectifier (SR) driving scheme for resonant converters. It is very suitable for high frequency, high efficiency and high power density dc-dc resonant converters with SRs. An LLC resonant converter with proposed synchronous rectification is designed and analyzed. With proposed driving scheme, SR body diode conduction is almost reduced to none. The reverse recovery

Dianbo Fu; Ya Liu; Fred C. Lee; Ming Xu

2008-01-01

341

Boost type three-phase diode rectifier using current resonant switch  

Microsoft Academic Search

This paper proposes a boost type single switching device three-phase diode rectifier with a current resonant switch to decrease switching loss and the total harmonic distortion (THD) of the input current. It is confirmed that a switching device in the proposed circuit operates in zero current switching by simulation. This paper also shows that the proposed circuit can decrease the

Akiteru Ueda; Yuichiro Ito; Yoshitaka Kurimoto; Akihiro Torii

2002-01-01

342

A high-efficiency low-voltage CMOS rectifier for harvesting energy in implantable devices.  

PubMed

We present, in this paper, a new full-wave CMOS rectifier dedicated for wirelessly-powered low-voltage biomedical implants. It uses bootstrapped capacitors to reduce the effective threshold voltage of selected MOS switches. It achieves a significant increase in its overall power efficiency and low voltage-drop. Therefore, the rectifier is good for applications with low-voltage power supplies and large load current. The rectifier topology does not require complex circuit design. The highest voltages available in the circuit are used to drive the gates of selected transistors in order to reduce leakage current and to lower their channel on-resistance, while having high transconductance. The proposed rectifier was fabricated using the standard TSMC 0.18 ?m CMOS process. When connected to a sinusoidal source of 3.3 V peak amplitude, it allows improving the overall power efficiency by 11% compared to the best recently published results given by a gate cross-coupled-based structure. PMID:23853177

Hashemi, S Saeid; Sawan, Mohamad; Savaria, Yvon

2012-08-01

343

46 CFR 62.35-50 - Tabulated monitoring and safety control requirements for specific systems.  

Code of Federal Regulations, 2013 CFR

...safety trip controls must not be provided. See 62.35-5(e)(2). 6. Transfer interlocks must be provided. 7. Semiconductor controlled rectifiers must have current limit controls. 8. Interlocks must be provided. See ...

2013-10-01

344

Expression and characterization of a canine hippocampal inwardly rectifying K+ current in Xenopus oocytes.  

PubMed Central

1. An inwardly rectifying potassium current expressed in Xenopus laevis oocytes injected with canine hippocampal poly(A)+ RNA was investigated with the two-microelectrode voltage clamp technique. 2. Xenopus oocytes injected with canine hippocampal poly(A)+ RNA expressed a current activated by hyperpolarization. This current contained an instantaneous and a time-dependent component. Both components were inwardly rectifying and could be blocked by extracellular Cs+ or Ba2+. 3. The expressed current was carried mainly by K+. Its reversal potential measured in different [K+]os could be fitted by the Nernst equation with a slope of -50.7 per tenfold change in [K+]o. Extracellular Cl- and Na+ made minimal contributions to the current. 4. The activation of the expressed current depended on both voltage and [K+]o. Activation started near EK and the activation curve shifted along the voltage axis in parallel with EK when [K+]o was altered. 5. The activation time constants of the expressed current also depended on both voltage and [K+]o. The voltage dependence of the time constants was bell-shaped and the peak value was at a potential 30-50 mV more negative than EK. The voltage dependence of the time constants shifted along the voltage axis when EK was changed. 6. The poly(A)+ RNA extracted from canine hippocampus was fractionated in a 10-31% linear sucrose gradient. The size of the mRNA required to express the inwardly rectifying current was estimated to be around 4 kb. 7. In conclusion, the expressed current is an inwardly rectifying potassium current. The canine hippocampal mRNA should be an excellent source for expression-cloning of the inward rectifier channel. PMID:1338458

Cui, J; Mandel, G; DiFrancesco, D; Kline, R P; Pennefather, P; Datyner, N B; Haspel, H C; Cohen, I S

1992-01-01

345

PV-5 automatic furnace control  

SciTech Connect

While refurbishing a Harwood Engineering, Inc. designed gas autoclave facility (designated PV-5) for hot isostatic pressing (HIP) of various materials at the Oak Ridge Y-12 Plant, a furnace power supply problem was encountered. One phase of the furnace's variable AC power supply was devastated when a fault condition occurred. In the process of diagnosing the cause of the fault and repairing the AC power supply of the 30KW furnace for the autoclave vessel, a recommendation to replace the existing, outdated 3-phase saturable-core reactor variable power supplies was implemented. Three new Silicon Controlled Rectifier (SCR) phase-angle fired AC power supplies, one for each phase of the 3-phase 480 volt circuit, were installed. To improve operator control over the new power supplies, a new 0--5 mA controller was connected as a slave to a process programmer to automatically heat the furnace according to preprogrammed temperature profiles. Data acquisition of the process parameters was enhanced by the installation of a hybrid strip chart recorder. 4 figs., 4 tabs.

Younkin, J.R.

1991-06-25

346

Mitochondria Provide the Main Source of Cytosolic ATP for Activation of Outward-rectifying K+ Channels in Mesophyll Protoplast of Chlorophyll-deficient Mutant Rice (OsCHLH) Seedlings  

Microsoft Academic Search

The role of mitochondria in providing intracellular ATP that controls the activity of plasma membrane out- ward-rectifying K channels was evaluated. The Os- CHLH rice mutant, which lacks chlorophyll in the thy- lakoids, was isolated by T-DNA gene trapping (Jung, K.-H., Hur, J., Ryu, C.-H., Choi, Y., Chung, Y.-Y., Miyao, A., Hirochika, H., and An, G. (2003) Plant Cell Physiol.

Chang-Hyo Goh; Stephen K. Roberts; Martin R. McAinsh; Alistair M. Hetherington; Youn-il Park; KyeHong Suh

2003-01-01

347

Silicon nitride/silicon carbide composite powders  

DOEpatents

Prepare silicon nitride-silicon carbide composite powders by carbothermal reduction of crystalline silica powder, carbon powder and, optionally, crystalline silicon nitride powder. The crystalline silicon carbide portion of the composite powders has a mean number diameter less than about 700 nanometers and contains nitrogen. The composite powders may be used to prepare sintered ceramic bodies and self-reinforced silicon nitride ceramic bodies.

Dunmead, Stephen D. (Midland, MI); Weimer, Alan W. (Midland, MI); Carroll, Daniel F. (Midland, MI); Eisman, Glenn A. (Midland, MI); Cochran, Gene A. (Midland, MI); Susnitzky, David W. (Midland, MI); Beaman, Donald R. (Midland, MI); Nilsen, Kevin J. (Midland, MI)

1996-06-11

348

Controlling the reproducibility of Coulomb blockade phenomena for gold nanoparticles on an organic monolayer/silicon system  

NASA Astrophysics Data System (ADS)

Two types of highly ordered organic layers were prepared on silicon modified with an amine termination for binding gold nanoparticles (AuNPs). These two grafted organic monolayers (GOMs), consisting of alkyl chains with seven or 11 carbon atoms, were grafted on oxide-free Si(111) surfaces as tunnel barriers between the silicon electrode and the AuNPs. Three kinds of colloidal AuNPs were prepared by reducing HAuCl4 with three different reactants: citrate (Turkevich synthesis, diameter 16 nm), ascorbic acid (diameter 9 nm), or NaBH4 (Natan synthesis, diameter 7 nm). Scanning tunnel spectroscopy (STS) was performed in a UHV STM at 40 K, and Coulomb blockade behaviour was observed. The reproducibility of the Coulomb behavior was analysed as a function of several chemical and physical parameters: size, crystallinity of the AuNPs, influence of surrounding surfactant molecules, and quality of the GOM/Si interface (degree of oxidation after the full processing). Samples were characterized with scanning tunneling microscope, STS, atomic force microscope, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), and high resolution transmission electronic microscope. We show that the reproducibility in observing Coulomb behavior can be as high as 80% with the Natan synthesis of AuNPs and GOMs with short alkyl chains.

Caillard, L.; Sattayaporn, S.; Lamic-Humblot, A.-F.; Casale, S.; Campbell, P.; Chabal, Y. J.; Pluchery, O.

2015-02-01

349

Diffusion-controlled growth of hydrogen pores in aluminum-silicon castings: In situ observation and modeling  

SciTech Connect

In situ observations were made of the nucleation and growth kinetics of hydrogen porosity during the directional solidification of aluminium-7 wt% silicon (Al7Si) with TiB{sub 2} grain refiner added, using an X-ray temperature gradient stage (XTGS). The effect of altering the solidification velocity on the growth rate and morphology of the porosity formed was characterized by tracking individual pores with digital analysis of the micro-focal video images. It was found that increasing the solidification velocity caused the pore radius to decrease and pore density to increase. Insight gained from the experimental results was used to develop a computational model of the evolution of hydrogen pores during solidification of aluminum-silicon cast alloys. The model solves for the diffusion-limited growth of the pores in spherical coordinates, using a deterministic solution of the grain nucleation and growth as a sub-model to calculate the parameters that depend upon the fraction solid. Sensitivity analysis was carried out to assess the effects of equiaxed grain density, pore density, initial hydrogen content and cooling rate. The model agrees with the experimental results within the resolution limits of the XTGS experiments performed.

Atwood, R.C.; Sridhar, S.; Zhang, W.; Lee, P.D.

2000-01-24

350

Controlling the reproducibility of Coulomb blockade phenomena for gold nanoparticles on an organic monolayer/silicon system.  

PubMed

Two types of highly ordered organic layers were prepared on silicon modified with an amine termination for binding gold nanoparticles (AuNPs). These two grafted organic monolayers (GOMs), consisting of alkyl chains with seven or 11 carbon atoms, were grafted on oxide-free Si(111) surfaces as tunnel barriers between the silicon electrode and the AuNPs. Three kinds of colloidal AuNPs were prepared by reducing HAuCl4 with three different reactants: citrate (Turkevich synthesis, diameter ?16 nm), ascorbic acid (diameter ?9 nm), or NaBH4 (Natan synthesis, diameter ?7 nm). Scanning tunnel spectroscopy (STS) was performed in a UHV STM at 40 K, and Coulomb blockade behaviour was observed. The reproducibility of the Coulomb behavior was analysed as a function of several chemical and physical parameters: size, crystallinity of the AuNPs, influence of surrounding surfactant molecules, and quality of the GOM/Si interface (degree of oxidation after the full processing). Samples were characterized with scanning tunneling microscope, STS, atomic force microscope, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), and high resolution transmission electronic microscope. We show that the reproducibility in observing Coulomb behavior can be as high as ?80% with the Natan synthesis of AuNPs and GOMs with short alkyl chains. PMID:25611611

Caillard, L; Sattayaporn, S; Lamic-Humblot, A-F; Casale, S; Campbell, P; Chabal, Y J; Pluchery, O

2015-02-13

351

Silicone-Acyclovir Controlled Release Devices Suppress Primary Herpes Simplex Virus-2 and Varicella Zoster Virus Infections In Vitro  

PubMed Central

Following initial infection, herpesviruses retreat into a permanent latent state with periodic reactivation resulting in an enhanced likelihood of transmission and clinical disease. The nucleoside analogue acyclovir reduces clinical symptoms of the three human alpha herpesviruses, HSV-1, HSV-2, and VZV. Long-term administration of acyclovir (ACV) can reduce the frequency and severity of reactivation, but its low bioavailability and short half-life require a daily drug regimen. Our lab is working to develop a subcutaneous delivery system to provide long-lasting, sustained release of ACV. Previously, we demonstrated that an implantable silicone (MED-4050) device, impregnated with ACV protected against HSV-1 both in vitro and in vivo. Here, we extend our in vitro observations to include protection against both HSV-2 and VZV. We also demonstrate protection against HSV-2 in vitro using MED-4750, a silicone polymer designed for long-term use in humans. When release of ACV from MED-4750 is quantitated on a daily basis, an initial burst of 5 days is observed, followed by a long period of slow release with near-zero-order kinetics, with an average daily release of 1.3923 0.5908??g ACV over days 2060. Development of a slow-release implant has the potential to significantly impact the treatment of human alpha herpesvirus infections. PMID:23983683

Berkower, Carol L.; Johnson, Nicole M.; Longdo, Stephen B.; McGusty-Robinson, Shenika O.; Semenkow, Samantha L.; Margulies, Barry J.

2013-01-01

352

TOPICAL REVIEW: Black silicon method X: a review on high speed and selective plasma etching of silicon with profile control: an in-depth comparison between Bosch and cryostat DRIE processes as a roadmap to next generation equipment  

NASA Astrophysics Data System (ADS)

An intensive study has been performed to understand and tune deep reactive ion etch (DRIE) processes for optimum results with respect to the silicon etch rate, etch profile and mask etch selectivity (in order of priority) using state-of-the-art dual power source DRIE equipment. The research compares pulsed-mode DRIE processes (e.g. Bosch technique) and mixed-mode DRIE processes (e.g. cryostat technique). In both techniques, an inhibitor is added to fluorine-based plasma to achieve directional etching, which is formed out of an oxide-forming (O2) or a fluorocarbon (FC) gas (C4F8 or CHF3). The inhibitor can be introduced together with the etch gas, which is named a mixed-mode DRIE process, or the inhibitor can be added in a time-multiplexed manner, which will be termed a pulsed-mode DRIE process. Next, the most convenient mode of operation found in this study is highlighted including some remarks to ensure proper etching (i.e. step synchronization in pulsed-mode operation and heat control of the wafer). First of all, for the fabrication of directional profiles, pulsed-mode DRIE is far easier to handle, is more robust with respect to the pattern layout and has the potential of achieving much higher mask etch selectivity, whereas in a mixed-mode the etch rate is higher and sidewall scalloping is prohibited. It is found that both pulsed-mode CHF3 and C4F8 are perfectly suited to perform high speed directional etching, although they have the drawback of leaving the FC residue at the sidewalls of etched structures. They show an identical result when the flow of CHF3 is roughly 30 times the flow of C4F8, and the amount of gas needed for a comparable result decreases rapidly while lowering the temperature from room down to cryogenic (and increasing the etch rate). Moreover, lowering the temperature lowers the mask erosion rate substantially (and so the mask selectivity improves). The pulsed-mode O2 is FC-free but shows only tolerable anisotropic results at -120 C. The downside of needing liquid nitrogen to perform cryogenic etching can be improved by using a new approach in which both the pulsed and mixed modes are combined into the so-called puffed mode. Alternatively, the use of tetra-ethyl-ortho-silicate (TEOS) as a silicon oxide precursor is proposed to enable sufficient inhibiting strength and improved profile control up to room temperature. Pulsed-mode processing, the second important aspect, is commonly performed in a cycle using two separate steps: etch and deposition. Sometimes, a three-step cycle is adopted using a separate step to clean the bottom of etching features. This study highlights an issue, known by the authors but not discussed before in the literature: the need for proper synchronization between gas and bias pulses to explore the benefit of three steps. The transport of gas from the mass flow controller towards the wafer takes time, whereas the application of bias to the wafer is relatively instantaneous. This delay causes a problem with respect to synchronization when decreasing the step time towards a value close to the gas residence time. It is proposed to upgrade the software with a delay time module for the bias pulses to be in pace with the gas pulses. If properly designed, the delay module makes it possible to switch on the bias exactly during the arrival of the gas for the bottom removal step and so it will minimize the ionic impact because now etch and deposition steps can be performed virtually without bias. This will increase the mask etch selectivity and lower the heat impact significantly. Moreover, the extra bottom removal step can be performed at (also synchronized!) low pressure and therefore opens a window for improved aspect ratios. The temperature control of the wafer, a third aspect of this study, at a higher etch rate and longer etch time, needs critical attention, because it drastically limits the DRIE performance. It is stressed that the exothermic reaction (high silicon loading) and ionic impact (due to metallic masks and/or exposed silicon) are the main sources of heat that might r

Jansen, H V; de Boer, M J; Unnikrishnan, S; Louwerse, M C; Elwenspoek, M C

2009-03-01

353

Preparation of Aligned Ultra-long and Diameter-controlled Silicon Oxide Nanotubes by Plasma Enhanced Chemical Vapor Deposition Using Electrospun PVP Nanofiber Template  

PubMed Central

Well-aligned and suspended polyvinyl pyrrolidone (PVP) nanofibers with 8 mm in length were obtained by electrospinning. Using the aligned suspended PVP nanofibers array as template, aligned ultra-long silicon oxide (SiOx) nanotubes with very high aspect ratios have been prepared by plasma-enhanced chemical vapor deposition (PECVD) process. The inner diameter (20200 nm) and wall thickness (1290 nm) of tubes were controlled, respectively, by baking the electrospun nanofibers and by coating time without sacrificing the orientation degree and the length of arrays. The micro-PL spectrum of SiOx nanotubes shows a strong bluegreen emission with a peak at about 514 nm accompanied by two shoulders around 415 and 624 nm. The bluegreen emission is caused by the defects in the nanotubes. PMID:21711837

2010-01-01

354

Nanometer-scale thickness control of amorphous silicon using isotropic wet-etching and low loss wire waveguide fabrication with the etched material  

NASA Astrophysics Data System (ADS)

Wet-etching with an organic alkaline solution was monitored in situ in semi-real time by optical reflection spectroscopy to achieve high resolution thickness control of hydrogenated amorphous silicon (a-Si:H) film for use in wire waveguides. Isotropic etching resulting from the intrinsic isotropic structure of a-Si:H led to uniform etching with a surface roughness of <1 nm. A moderate etching rate enabled accurate endpoint detection with a resolution of ?1 nm at room temperature. A wire waveguide made of the etched a-Si:H film had a low propagation loss of 1.2 dB/cm, which was almost equivalent to that of an unetched one.

Furuya, K.; Nakanishi, K.; Takei, R.; Omoda, E.; Suzuki, M.; Okano, M.; Kamei, T.; Mori, M.; Sakakibara, Y.

2012-06-01

355

Highly controllable and stable quantized conductance and resistive switching mechanism in single-crystal TiO2 resistive memory on silicon.  

PubMed

TiO2 is being widely explored as an active resistive switching (RS) material for resistive random access memory. We report a detailed analysis of the RS characteristics of single-crystal anatase-TiO2 thin films epitaxially grown on silicon by atomic layer deposition. We demonstrate that although the valence change mechanism is responsible for the observed RS, single-crystal anatase-TiO2 thin films show electrical characteristics that are very different from the usual switching behaviors observed for polycrystalline or amorphous TiO2 and instead very similar to those found in electrochemical metallization memory. In addition, we demonstrate highly stable and reproducible quantized conductance that is well controlled by application of a compliance current and that suggests the localized formation of conducting Magnli-like nanophases. The quantized conductance observed results in multiple well-defined resistance states suitable for implementation of multilevel memory cells. PMID:25072099

Hu, Chengqing; McDaniel, Martin D; Posadas, Agham; Demkov, Alexander A; Ekerdt, John G; Yu, Edward T

2014-08-13

356

Small-molecule modulators of inward rectifier K+ channels: recent advances and future possibilities  

PubMed Central

Inward rectifier potassium (Kir) channels have been postulated as therapeutic targets for several common disorders including hypertension, cardiac arrhythmias and pain. With few exceptions, however, the small-molecule pharmacology of this family is limited to nonselective cardiovascular and neurologic drugs with off-target activity toward inward rectifiers. Consequently, the actual therapeutic potential and drugability of most Kir channels has not yet been determined experimentally. The purpose of this review is to provide a comprehensive summary of publicly disclosed Kir channel small-molecule modulators and highlight recent targeted drug-discovery efforts toward Kir1.1 and Kir2.1. The review concludes with a brief speculation on how the field of Kir channel pharmacology will develop over the coming years and a discussion of the increasingly important role academic laboratories will play in this progress. PMID:20543968

Bhave, Gautam; Lonergan, Daniel; Chauder, Brian A; Denton, Jerod S

2010-01-01

357

Characterization of deep electron traps in 4H-SiC Junction Barrier Schottky rectifiers  

NASA Astrophysics Data System (ADS)

Conventional deep level transient spectroscopy (DLTS) technique was used to study deep electron traps in 4H-SiC Junction Barrier Schottky (JBS) rectifiers. 4H-SiC epitaxial layers, doped with nitrogen and grown on standard n+-4H-SiC substrates were exposed to low-dose aluminum ion implantation process under the Schottky contact in order to form both JBS grid and junction termination extension (JTE), and assure good rectifying properties of the diodes. Several deep electron traps were revealed and attributed to impurities or intrinsic defects in 4H-SiC epitaxial layers, on the basis of comparison of their electrical parameters (i.e. activation energies, apparent capture cross sections and concentrations) with previously published results.

Gelczuk, ?.; D?browska-Szata, M.; Sochacki, M.; Szmidt, J.

2014-04-01

358

High Efficiency 3-Phase Cmos Rectifier with Step Up and Regulated  

E-print Network

This paper presents several design issues related to the monolithic integration of a 3-phase AC to DC low voltage, low power rectifier for 3-phase micro source electrical conditioning. Reduced input voltage operation (down to 1V), high efficiency, and output voltage regulations are implemented, based on commercially available CMOS technology. Global design and system issues are detailed. The management of start-up sequences under self supplied conditions as well as output voltage regulations are specifically addressed. Simulation results, practical implementation and validation are presented. They are based on the association of three micro elements : a 3-phase micro-generator, a stand alone 3-phase AC to DC integrated rectifier, and an output voltage conditioner based on a commercially available IC.

Crebier, J -C; Raisigel, H; Deleage, O; Delamare, J; Cugat, O

2008-01-01

359

A new high performance AC to DC rectifier with input power factor correction and harmonic reduction capacity  

E-print Network

Many conventional switching power supplies in data processing equipment and low power motor drive systems operate by rectifying the input ac line voltage and filtering it with large electrolytic capacitors. Because this process involves both...

Martinez, Roberto

2012-06-07

360

Highly efficient C-band circularly polarized rectifying antenna array for wireless microwave power transmission  

Microsoft Academic Search

This paper reports a new circularly polarized (CP) high-gain, high-efficiency rectifying antenna (rectenna) array designed in a coplanar stripline (CPS) circuit. The array can maintain a constant dc output voltage regardless of its broadside orientation. The array is etched on Rogers Duroid 5870 substrate with ?r=2.33 and 10 mil thickness. High-gain dual rhombic loop antennas and a reflecting plane are

Berndie Strassner; Kai Chang

2003-01-01

361

5.8GHz circularly polarized rectifying antenna for wireless microwave power transmission  

Microsoft Academic Search

This paper reports a new circularly polarized (CP) high-gain high-efficiency rectifying antenna (rectenna). The CP rectenna can be rotated and still maintain a constant dc output voltage. The high-gain antenna has an advantage of reducing the total number of rectenna elements to cover a fixed area. The rectenna is etched on Rogers Duroid 5870 substrate with εr=2.33 and 10 mil

Berndie Strassner; Kai Chang

2002-01-01

362

5.8 GHz circular polarized rectifying antenna for microwave power transmission  

Microsoft Academic Search

This paper reports a new 5.8 GHz circular polarized (CP) high gain, high-efficiency rectifying antenna (rectenna). The CP rectenna can be rotated and still maintain a constant output voltage. A high-gain dual rhombic loop antenna and a reflecting plane are used to achieve a circular polarized antenna gain of 10.5 dB, a 2:1 VSWR bandwidth of 10 %, and average

Berndie Strassner; Kai Chang

2001-01-01

363

A Novel Driving Scheme for Synchronous Rectifiers in LLC Resonant Converters  

Microsoft Academic Search

This paper proposes a novel synchronous rectifier (SR) driving scheme for resonant converters. It is very suitable for high-frequency, high-efficiency, and high-power-density dc-dc resonant converters with SRs. In this paper, an LLC resonant converter with the proposed synchronous rectification is designed and analyzed. With the proposed driving scheme, the SR body diode conduction is reduced to almost zero. The driving

Dianbo Fu; Ya Liu; Fred C. Lee; Ming Xu

2009-01-01

364

Extensive Editing of mRNAs for the Squid Delayed Rectifier K + Channel Regulates Subunit Tetramerization  

Microsoft Academic Search

We report the extensive editing of mRNAs that encode the classical delayed rectifier K+ channel (SqKv1.1A) in the squid giant axon. Using a quantitative RNA editing assay, 14 adenosine to guanine transitions were identified, and editing efficiency varied tremendously between positions. Interestingly, half of the sites are targeted to the T1 domain, important for subunit assembly. Other sites occur in

Joshua J. C. Rosenthal; Francisco Bezanilla

2002-01-01

365

New Step-Up and Step-Down 18Pulse Direct Asymmetric Autotransformer Rectifier Units  

Microsoft Academic Search

This paper presents two new step-up and step-down 18-pulse direct asymmetric autotransformer rectifier units for aircraft applications. The converters are designed to operate with variable frequency power supplies (400-800 Hz), while meeting tight harmonic, power factor and output voltage requirements. The main features of the proposed converters are: a minimum number of windings used to achieve the step-up and step-down

Rolando P. Burgos; Alexander Uan-Zo-li; Frederic Lacaux; Arman Roshan; Fred Wang; Dushan Boroyevich

2005-01-01

366

Protein expression of G-protein inwardly rectifying potassium channels (GIRK) in breast cancer cells  

Microsoft Academic Search

BACKGROUND: Previous data from our laboratory has indicated that a functional link exists between the G-protein-coupled inwardly rectifying potassium (GIRK) channel and the beta-adrenergic receptor pathway in breast cancer cell lines, and these pathways were involved in growth regulation of these cells. Alcohol is an established risk factor for breast cancer and has been found to open GIRK. In order

Madhu S Dhar; Howard K Plummer III

2006-01-01

367

Development of a New Permanent-Magnet BLDC Generator Using 12Phase Half-Wave Rectifier  

Microsoft Academic Search

Six-phase double-star armature windings of a synchronous generator are essentially equivalent to 12-phase symmetrical windings displaced in turn by 30deg. This paper proposes and implements a new permanent-magnet brushless dc (BLDC) generator using 12-phase half-wave rectifier. Characteristic of output voltage is analyzed according to the star graph of slot potential, and the design constraints of armature windings are provided. Simulation

Zhuoran Zhang; Yangguang Yan; Shanshui Yang; Zhou Bo

2009-01-01

368

Large area silicon sheet by EFG  

NASA Technical Reports Server (NTRS)

Some hypotheses to explain both of these features are advanced and the possible implications for solar cell performance are touched upon. The multiple ribbon growth system has shown a number of flaws with respect to the reliability of the basic furnace design. These definitely need to be rectified before any significant demonstration of multiple ribbon growth can proceed. The cartridges, however, have performed quite well. The work on 3" cartridge design and automatic controls has proceeded nearly on schedule and the report contains a detailed description of the approach and the equipment to be used for automatic control of ribbon growth.

1977-01-01

369

New single-switch three-phase high power factor rectifiers using multi-resonant zero current switching  

Microsoft Academic Search

New single-switch three-phase high power factor rectifiers are introduced which have continuous input and output currents. By the use of a multi-resonant scheme, the transistor operates with zero current switching and the diodes operate with zero voltage switching. These multi-resonant rectifiers with a single transistor are capable of drawing a higher quality input current waveform at nearly unity power factor

Yungtaek Jang; Robert W. Erickson

1994-01-01

370

Inverse agonist-like action of cadmium on G-protein-gated inward-rectifier K{sup +} channels  

SciTech Connect

Highlights: {yields} We examined allosteric control of K{sup +} channel gating. {yields} We identified a high-affinity site for Cd{sup 2+} to inhibit Kir3.2 activity. {yields} The 6-coordination geometry supports the binding. {yields} Cd{sup 2+} inhibits Kir3.2 by trapping the conformation in the closed state. -- Abstract: The gate at the pore-forming domain of potassium channels is allosterically controlled by a stimulus-sensing domain. Using Cd{sup 2+} as a probe, we examined the structural elements responsible for gating in an inward-rectifier K{sup +} channel (Kir3.2). One of four endogenous cysteines facing the cytoplasm contributes to a high-affinity site for inhibition by internal Cd{sup 2+}. Crystal structure of its cytoplasmic domain in complex with Cd{sup 2+} reveals that octahedral coordination geometry supports the high-affinity binding. This mode of action causes the tethering of the N-terminus to CD loop in the stimulus-sensing domain, suggesting that their conformational changes participate in gating and Cd{sup 2+} inhibits Kir3.2 by trapping the conformation in the closed state like 'inverse agonist'.

Inanobe, Atsushi, E-mail: inanobe@pharma2.med.osaka-u.ac.jp [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan) [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan); Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka (Japan); Matsuura, Takanori [Laboratory of Protein Informatics, Institute for Protein Research, Osaka University, Osaka (Japan)] [Laboratory of Protein Informatics, Institute for Protein Research, Osaka University, Osaka (Japan); Nakagawa, Atsushi [Laboratory of Supramolecular Crystallography, Institute for Protein Research, Osaka University, Osaka (Japan)] [Laboratory of Supramolecular Crystallography, Institute for Protein Research, Osaka University, Osaka (Japan); Kurachi, Yoshihisa, E-mail: ykurachi@pharma2.med.osaka-u.ac.jp [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan) [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan); Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka (Japan)

2011-04-08

371

Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes  

NASA Astrophysics Data System (ADS)

The mitigating impact of thermal and rectified radio frequency (RF) sheath potentials on the peeling-ballooning modes is studied non-linearly by employing a two-fluid three-field simulation model based on the BOUT++ framework. Additional shear flow and the Kelvin-Helmholtz effect due to the thermal and rectified RF sheath potential are induced. It is found that the shear flow increases the growth rate while the K-H effect decreases the growth rate slightly when there is a density gradient, but the energy loss of these cases is suppressed in the nonlinear phase. The stronger external electrostatic field due to the sheaths has a more significant effect on the energy loss suppression. From this study, it is found the growth rate in the linear phase mainly determines the onset of edge-localized modes, while the mode spectrum width in the nonlinear phase has an important impact on the turbulent transport. The wider mode spectrum leads to weaker turbulent transport and results in a smaller energy loss. Due to the thermal sheath and rectified RF sheath potential in the scrape-off-layer, the modified shear flow tears apart the peeling-ballooning filament and makes the mode spectrum wider, resulting in less energy loss. The perturbed electric potential and the parallel current near the sheath region is also suppressed locally due to the sheath boundary condition.

Gui, B.; Xu, X. Q.; Myra, J. R.; D'Ippolito, D. A.

2014-11-01

372

Low cost, p-ZnO/n-Si, rectifying, nano heterojunction diode: Fabrication and electrical characterization  

PubMed Central

Summary A low cost, highly rectifying, nano heterojunction (p-ZnO/n-Si) diode was fabricated using solution-processed, p-type, ZnO nanoparticles and an n-type Si substrate. p-type ZnO nanoparticles were synthesized using a chemical synthesis route and characterized by XRD and a Hall effect measurement system. The device was fabricated by forming thin film of synthesized p-ZnO nanoparticles on an n-Si substrate using a dip coating technique. The device was then characterized by currentvoltage (IV) and capacitancevoltage (CV) measurements. The effect of UV illumination on the IV characteristics was also explored and indicated the formation of a highly rectifying, nano heterojunction with a rectification ratio of 101 at 3 V, which increased nearly 2.5 times (232 at 3 V) under UV illumination. However, the cut-in voltage decreases from 1.5 V to 0.9 V under UV illumination. The fabricated device could be used in switches, rectifiers, clipper and clamper circuits, BJTs, MOSFETs and other electronic circuitry. PMID:25551049

Kabra, Vinay; Malik, M M

2014-01-01

373

Microfluidic rectifier based on poly(dimethylsiloxane) membrane and its application to a micropump  

PubMed Central

A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2?m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200??m and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump. PMID:24404051

Wang, Yao-Nan; Tsai, Chien-Hsiung; Fu, Lung-Ming; Lin Liou, Lung-Kai

2013-01-01

374

Impurity diffusion process for silicon semiconductors is fast and precise  

NASA Technical Reports Server (NTRS)

Impurity diffusion process produces precision silicon semiconductor junctions economically and fast. Oxide is deposited on a silicon wafer and a controlled concentration of impurity atoms in gaseous form is simultaneously introduced into the reaction.

Mc louski, R. M.; Mc Louski, R. M.; Skouson, G. W.

1965-01-01

375

Failure rates for accelerated acceptance testing of silicon transistors  

NASA Technical Reports Server (NTRS)

Extrapolation tables for the control of silicon transistor product reliability have been compiled. The tables are based on a version of the Arrhenius statistical relation and are intended to be used for low- and medium-power silicon transistors.

Toye, C. R.

1968-01-01

376

Silicon Valley  

NSDL National Science Digital Library

It is no exaggeration to say that the innovations of the Silicon Valley have shaped our world. This excellent episode from the PBS series, American Experience, provides insight into how the magic happened, starting in 1957 when eight brilliant physicists quit their day jobs at the Shockley Semiconductor Company â and invented the microchip. Visitors will want to start with the Introduction, a first-rate synopsis of the early days of Silicon Valley. Next, click the Preview link for a teaser of the full-length film. A number of links feature clips from the documentary, and a full-length transcript may be downloaded free of cost. Also, offer your comments on the history of Silicon Valley in the Share Your Story section, and peruse the Timeline and the Photo Gallery.

377

High Efficiency Silicon Photonic Interconnects  

NASA Astrophysics Data System (ADS)

Silicon photonic has provided an opportunity to enhance future processor speed by replacing copper interconnects with an on chip optical network. Although photonics are supposed to be efficient in terms of power consumption, speed, and bandwidth, the existing silicon photonic technologies involve problems limiting their efficiency. Examples of limitations to efficiency are transmission loss, coupling loss, modulation speed limited by electro-optical effect, large amount of energy required for thermal control of devices, and the bandwidth limit of existing optical routers. The objective of this dissertation is to investigate novel materials and methods to enhance the efficiency of silicon photonic devices. The first part of this dissertation covers the background, theory and design of on chip optical interconnects, specifically silicon photonic interconnects. The second part describes the work done to build a 300mm silicon photonic library, including its process flow, comprised of basic elements like electro-optical modulators, germanium detectors, Wavelength Division Multiplexing (WDM) interconnects, and a high efficiency grating coupler. The third part shows the works done to increase the efficiency of silicon photonic modulators, unitizing the chi(3) nonlinear effect of silicon nanocrystals to make DC Kerr effect electro-optical modulator, combining silicon with lithium niobate to make chi(2) electro-optical modulators on silicon, and increasing the efficiency of thermal control by incorporating micro-oven structures in electro-optical modulators. The fourth part introduces work done on dynamic optical interconnects including a broadband optical router, single photon level adiabatic wavelength conversion, and optical signal delay. The final part summarizes the work and talks about future development.

Cao, Liang

378

Production of electronic grade lunar silicon by disproportionation of silicon difluoride  

NASA Technical Reports Server (NTRS)

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

Agosto, William N.

1993-01-01

379

Damage Mechanisms and Controlled Crack Propagation in a Hot Pressed Silicon Nitride Ceramic. Ph.D. Thesis - Northwestern Univ., 1993  

NASA Technical Reports Server (NTRS)

The subcritical growth of cracks from pre-existing flaws in ceramics can severely affect the structural reliability of a material. The ability to directly observe subcritical crack growth and rigorously analyze its influence on fracture behavior is important for an accurate assessment of material performance. A Mode I fracture specimen and loading method has been developed which permits the observation of stable, subcritical crack extension in monolithic and toughened ceramics. The test specimen and procedure has demonstrated its ability to generate and stably propagate sharp, through-thickness cracks in brittle high modulus materials. Crack growth for an aluminum oxide ceramic was observed to be continuously stable throughout testing. Conversely, the fracture behavior of a silicon nitride ceramic exhibited crack growth as a series of subcritical extensions which are interrupted by dynamic propagation. Dynamic initiation and arrest fracture resistance measurements for the silicon nitride averaged 67 and 48 J/sq m, respectively. The dynamic initiation event was observed to be sudden and explosive. Increments of subcritical crack growth contributed to a 40 percent increase in fracture resistance before dynamic initiation. Subcritical crack growth visibly marked the fracture surface with an increase in surface roughness. Increments of subcritical crack growth loosen ceramic material near the fracture surface and the fracture debris is easily removed by a replication technique. Fracture debris is viewed as evidence that both crack bridging and subsurface microcracking may be some of the mechanisms contributing to the increase in fracture resistance. A Statistical Fracture Mechanics model specifically developed to address subcritical crack growth and fracture reliability is used together with a damaged zone of material at the crack tip to model experimental results. A Monte Carlo simulation of the actual experiments was used to establish a set of modeling input parameters. It was demonstrated that a single critical parameter does not characterize the conditions required for dynamic initiation. Experimental measurements for critical crack lengths, and the energy release rates exhibit significant scatter. The resulting output of the model produces good agreement with both the average values and scatter of experimental measurements.

Calomino, Anthony Martin

1994-01-01

380

2428 IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 5, SEPTEMBER 2008 A Modular Strategy for Control and Voltage  

E-print Network

results. Index Terms--Active rectifier, cascaded H-bridge, multilevel converter, power-factor correction), and cascaded H-bridge (CHB) converters. Among them, the CHB topology is particularly attractive in high for Control and Voltage Balancing of Cascaded H-Bridge Rectifiers Hossein Iman-Eini, Jean-Luc Schanen, Senior

Paris-Sud XI, Université de

381

Guided photoluminescence study ofNd-doped Silicon Rich Silicon Oxide and Silicon Rich Silicon Nitride waveguides  

E-print Network

Guided photoluminescence study ofNd-doped Silicon Rich Silicon Oxide and Silicon Rich Silicon Abstract: Planar waveguides made of Nd3+ -doped silicon rich silicon oxide (SRSO) and silicon rich silicon on silicon nitride planar waveguide for a sample length superior to 1.5 cm. The guided fluorescence decays

Paris-Sud XI, Université de

382

Advances in the understanding of low molecular weight silicon formation and implications for control by AMC filters  

NASA Astrophysics Data System (ADS)

Trimethylsilanol (TMS) is a low molecular weight / low boiling point silicon-containing, airborne contaminant that has received increased interest over the past few years as an important cause for contamination of optical surfaces in lithography equipment. TMS is not captured well by carbon-based filters, and hexamethyldisiloxane (HMDSO), even though captured well, can be converted to TMS when using acidic filter media commonly used for ammonia removal. TMS and HMDSO co-exist in a chemical equilibrium, which is affected by the acidity and moisture of their environment. This publication shows that HMDSO is converted to TMS by acidic media at concentrations typically found in cleanroom environments. This is contrary to published results that show a re-combination of TMS to HMDSO on acid media. We also demonstrate that, based on its conversion to TMS, HMDSO is not a suitable test compound for hybrid chemical filter performance, as the apparent lifetime/capacity of the filter can be substantially skewed towards larger numbers when conversion to TMS is involved. We show lifetime test results with toluene and HMDSO on acidic and non-acidic filter media. Appropriately designed, asymmetric hybrid chemical filters significantly minimize or eliminate the conversion of HMDSO to TMS, thereby reducing the risk to scanner optical elements. Similarly, such filters can also prevent or reduce acid-sensitive reactions of other AMC when passing through filter systems.

Lobert, Jrgen M.; Cate, Philip W.; Ruede, David J.; Wildgoose, Joseph R.; Miller, Charles M.; Gaudreau, John C.

2010-03-01

383

Silicon surface passivation by silicon nitride deposition  

NASA Technical Reports Server (NTRS)

Silicon nitride deposition was studied as a method of passivation for silicon solar cell surfaces. The following three objectives were the thrust of the research: (1) the use of pecvd silicon nitride for passivation of silicon surfaces; (2) measurement techniques for surface recombination velocity; and (3) the importance of surface passivation to high efficiency solar cells.

Olsen, L. C.

1984-01-01

384

Performance of a Thin-Wndow Silicon Drift Detector X-Ray Fluorescence Spectrometer  

SciTech Connect

Several sets of hexagonal Silicon Drift Detector (SDD) arrays were produced by Brookhaven National Laboratory (BNL) and by the commercial vendor, KETEK. These detector arrays were tested at BNL. Each array consists of 14 independent SDD detectors (pixels) and two additional test pixels located at two corners of the array. The side of the detector upon which the X-ray radiation is incident (window side) has a thin junction covering the entire active area. The opposite side (device side) contains a drift-field electrode structure in the form of a hexagonal spiral and an electron collecting anode. There are four guard rings surrounding the 14-pixel array area on each side of the detector. Within each array, seven pixels have aluminum field plates - interrupted spirals that stabilize the electric potential under the Si-SiO{sub 2} interface, while the other seven do not. Three bias voltages are applied to control the drift field in the silicon volume; one is applied to a rectifying contact surrounding the central anode (one for each pixel), one is applied to the detector entrance window (common to the full array), and a third bias is applied to a contact on the outer portion of the spiral, common to all pixels in the array. Some arrays were recently tested in NSLS beam line U3C at BNL. For this work, we installed the complete assemblies in the vacuum and cooled them to -27degC. During this beam run, we collected spectra for energies ranging between 350 and 900 eV in several pixels, some with field plates and others without. The detailed testing results of several arrays are reported here.

Carini, G.; Chen, W.; De Geronimo, G.; Gaskin, J.; Keister, J.; Li, Z.; Ramey, B.; Rehak, P. and Siddons, P.

2009-10-01

385

Evaluation of acceleration and deceleration cardiac processes using phase-rectified signal averaging in healthy and idiopathic dilated cardiomyopathy subjects.  

PubMed

The aim of the present study was to investigate the suitability of the Phase-Rectified Signal Averaging (PRSA) method for improved risk prediction in cardiac patients. Moreover, this technique, which separately evaluates acceleration and deceleration processes of cardiac rhythm, allows the effect of sympathetic and vagal modulations of beat-to-beat intervals to be characterized. Holter recordings of idiopathic dilated cardiomyopathy (IDC) patients were analyzed: high-risk (HR), who suffered sudden cardiac death (SCD) during the follow-up; and low-risk (LR), without any kind of cardiac-related death. Moreover, a control group of healthy subjects was analyzed. PRSA indexes were analyzed, for different time scales T and wavelet scales s, from RR series of 24h-ECG recordings, awake periods and sleep periods. Also, the behavior of these indexes from simulated data was analyzed and compared with real data results. Outcomes demonstrated the PRSA capacity to significantly discriminate healthy subjects from IDC patients and HR from LR patients on a higher level than traditional temporal and spectral measures. The behavior of PRSA indexes agrees with experimental evidences related to cardiac autonomic modulations. Also, these parameters reflect more regularity of the autonomic nervous system (ANS) in HR patients. PMID:25585858

Bas, Rosana; Vallverd, Montserrat; Valencia, Jose F; Voss, Andreas; de Luna, Antonio Bays; Caminal, Pere

2015-02-01

386

Silicon Nanowire Devices  

NASA Astrophysics Data System (ADS)

Metal-catalyzed, self-assembled, one-dimensional semiconductor nanowires are being considered as possible device elements to augment and supplant conventional electronics and to extend the use of CMOS beyond the physical and economic limits of conventional technology. Such nanowires can create nanostructures without the complexity and cost of extremely fine scale lithography. The well-known and controllable properties of silicon make silicon nanowires especially attractive. Easy integration with conventional electronics will aid their acceptance and incorporation. For example, connections can be formed to both ends of a nanowire by growing it laterally from a vertical surface formed by etching the top silicon layer of a silicon-on-insulator structure into isolated electrodes. Field-effect structures are one class of devices that can be readily built in silicon nanowires. Because the ratio of surface to volume in a thin nanowire is high, conduction through the nanowire is very sensitive to surface conditions, making it effective as the channel of a field-effect transistor or as the transducing element of a gas or chemical sensor. As the nanowire diameter decreases, a greater fraction of the mobile charge can be modulated by a given external charge, increasing the sensitivity. Having the gate of a nanowire transistor completely surround the nanowire also enhances the sensitivity. For a field-effect sensor to be effective, the charge must be physically close to the nanowire so that the majority of the compensating charge is induced in the nanowire and so that ions in solution do not screen the charge. Because only induced charge is being sensed, a coating that selectively binds the target species should be added to the nanowire surface to distinguish between different species in the analyte. The nanowire work at Hewlett-Packard Laboratories was supported in part by the Defense Advanced Research Projects Agency.

Kamins, Theodore

2006-03-01

387

Starting Material Silicon substrate  

E-print Network

Starting Material Silicon substrate 150 mm, p-type, , 36-63 ohm-cm Attila Horvath 2005 #12;Pad Oxidation and Nitride Deposition Silicon substrate Pad oxide = 250A Silicon nitride = 2200A Attila Horvath 2005 #12;N-Well Photo and Nitride Etch Silicon substrate Pad oxide Silicon nitride Photo resist Attila

Healy, Kevin Edward

388

Correlation between barrier inhomogeneities of 4H-SiC 1 A/600 V Schottky rectifiers and deep-level defects revealed by DLTS and Laplace DLTS  

NASA Astrophysics Data System (ADS)

Electrical properties of commercial silicon carbide (SiC) Schottky rectifiers are investigated through the measurement and analysis of the forward current-voltage (I-V) and reverse capacitance-voltage (C-V) characteristics in a large temperature range. Some of devices show distinct discrepancies in specific ranges of their electrical characteristics, especially the excess current dominates at voltage <1 V and temperature <300 K. Standard deep level transient spectroscopy (DLTS) revealed the presence of a single deep-level defect with activation energy of about 0.3 eV, exhibiting the features characteristic for extended defects (e.g. dislocations), such as logarithmic capture kinetics. Furthermore, high-resolution Laplace DLTS showed that this deep level consists actually of three closely spaced levels with activation energies ranging from about 0.26 eV to 0.29 eV. A strong correlation between these two techniques implies that the revealed trap level is due to extended defects surrounded by point traps or clusters of defects. On the basis of obtained specific features of the deep-level defect, it was proposed that this defect is arguably responsible for the observed Schottky barrier inhomogeneities.

Gelczuk, ?.; Kamyczek, P.; P?aczek-Popko, E.; D?browska-Szata, M.

2014-09-01

389

The properties and distribution of inward rectifier potassium currents in pig coronary arterial smooth muscle.  

PubMed Central

1. Whole-cell potassium currents were studied in single smooth muscle cells enzymatically isolated from pig coronary arteries. 2. In cells isolated from small diameter branches of the left anterior descending coronary artery (LAD), an inward rectifier potassium current (IK(IR)) was identified, which was inhibited by extracellular barium ions, suggesting the presence of inward rectifier potassium (KIR) channels. 3. The conductance for IK(IR) measured in 6, 12, 60 and 140 mM extracellular potassium was a function of membrane potential and the extracellular potassium concentration. 4. On hyperpolarization, IK(IR) activated along an exponential time course with a time constant that was voltage dependent. 5. Inward rectifier current was compared in cells isolated from coronary vessels taken from different points along the vascular tree. Current density was greater in cells isolated from small diameter coronary arteries; at -140 mV it was -20.5 +/- 4.4 pA pF-1 (n = 23) in 4th order branches of the LAD, but -0.8 +/- 0.2 pA pF-1 (n = 11) in the LAD itself. 6. In contrast to IK(IR), there was little effect of arterial diameter on the density of voltage-dependent potassium current; densities at +30 mV were 12.8 +/- 1.3 pA pF-1 (n = 19) in 4th order branches and 17.4 +/- 3.1 pA pF-1 (n = 11) in the LAD. 7. We conclude that KIR channels are present in pig coronary arteries, and that they are expressed at a higher density in small diameter arteries. The presence of an enhanced IK(IR) may have functional consequences for the regulation of cell membrane potential and tone in small coronary arteries. PMID:8865069

Quayle, J M; Dart, C; Standen, N B

1996-01-01

390

Silicon Micromachined Microlens Array for THz Antennas  

NASA Technical Reports Server (NTRS)

5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a smooth curvature. The measured height of the silicon microlens is about 280 microns. In this case, the original height of the photoresist was 210 microns. The change was due to the etching selectivity of 1.33 between photoresist and silicon. The measured surface roughness of the silicon microlens shows the peak-to-peak surface roughness of less than 0.5 microns, which is adequate in THz frequency. For example, the surface roughness should be less than 7 microns at 600 GHz range. The SEM (scanning electron microscope) image of the microlens confirms the smooth surface. The beam pattern at 550 GHz shows good directivity.

Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

2013-01-01

391

Progress in semicrystalline silicon solar cell fabrication  

NASA Astrophysics Data System (ADS)

Several recent advances made in the fabrication technology of semicrystalline silicon solar cells are reviewed in this paper. Recent work has indicated that: (1) semicrystalline silicon solar cell performance is mainly controlled by intragrain defect densities and not only by the grain boundaries, (2) processing parameters for low cost, high throughput techniques require more optimization when semicrystalline silicon substrates are used, and (3) reasonable cell efficiencies have been achieved using a low cost thin-film epitaxial layer on UMG-Silicon coupled with low cost screen printing technology.

Mertens, R.; Cheek, G.; Depauw, P.; Frisson, L.

392

Making silicon stronger.  

SciTech Connect

Silicon microfabrication has seen many decades of development, yet the structural reliability of microelectromechanical systems (MEMS) is far from optimized. The fracture strength of Si MEMS is limited by a combination of poor toughness and nanoscale etch-induced defects. A MEMS-based microtensile technique has been used to characterize the fracture strength distributions of both standard and custom microfabrication processes. Recent improvements permit 1000's of test replicates, revealing subtle but important deviations from the commonly assumed 2-parameter Weibull statistical model. Subsequent failure analysis through a combination of microscopy and numerical simulation reveals salient aspects of nanoscale flaw control. Grain boundaries, for example, suffer from preferential attack during etch-release thereby forming failure-critical grain-boundary grooves. We will discuss ongoing efforts to quantify the various factors that affect the strength of polycrystalline silicon, and how weakest-link theory can be used to make worst-case estimates for design.

Boyce, Brad Lee

2010-11-01

393

Vacuum evaporated porous silicon photonic interference filters  

Microsoft Academic Search

Porous materials with nanometer-scale structure are important in a wide variety of applications including electronics, photonics, biomedicine, and chemistry. Recent interest focuses on understanding and controlling the properties of these materials. Here we demonstrate porous silicon interference filters, deposited in vacuum with a technique that enables continuous variation of the refractive index between that of bulk silicon and that of

Kate Kaminska; Tim Brown; Gisia Beydaghyan; Kevin Robbie

2003-01-01

394

Tunable micro-electromechanical grating in silicon  

Microsoft Academic Search

In this paper, we propose a solution for simple, fast and easily controllable way of tuning silicon gratings using Micro Electro Mechanical Systems (MEMS) to deform the grating itself. Basically the idea is to deform mechanically a silicon grating using electrostatic actuators, enabling pitch tuning over a large proportion (more than 50% is easily achievable with our approach). Moreover we

Yves-Alain Peter; Fatou Binetou Kon; Jonathan Masson; Nicolas Godbout

2006-01-01

395

High Performance Silicon Nanowire Field Effect Transistors  

Microsoft Academic Search

Silicon nanowires can be prepared with single-crystal structures, diameters as small as several nanometers and controllable hole and electron doping, and thus represent powerful building blocks for nanoelectronics devices such as field effect transistors. To explore the potential limits of silicon nanowire transistors, we have examined the influence of source-drain contact thermal annealing and surface passivation on key transistor properties.

Yi Cui; Zhaohui Zhong; Deli Wang; Wayne U. Wang; Charles M. Lieber

2003-01-01

396

Asymmetric Die Grows Purer Silicon Ribbon  

NASA Technical Reports Server (NTRS)

Concentration of carbide impurities in silicon ribbon is reduced by growing crystalline ribbon with die one wall higher than other. Height difference controls shape of meniscus at liquid/crystal interface and concentrates silicon carbide impurity near one of broad faces. Opposite face is left with above-average purity. Significantly improves efficiency of solar cells made from ribbon.

Kalejs, J. P.; Chalmers, B.; Surek, T.

1983-01-01

397

Rectified motion in an asymmetric channel: the role of hydrodynamic interactions with walls  

E-print Network

Dynamics of a Brownian particle in an asymmetric micro-channel that is subjected to an external oscillating force is numerically analyzed. In addition to the elastic collisions with the walls that are kind of short range interactions, the long range hydrodynamic influences of the walls have been considered. We demonstrate how the geometrical parameters of the channel change the rectified current of the particle. As a result of numerical calculations, we show that long range hydrodynamic interactions with walls, decrease the efficiency of the Brownian ratchet.

B. Golshaei; A. Najafi

2014-09-28

398

Different ionic selectivities for connexins 26 and 32 produce rectifying gap junction channels.  

PubMed Central

The functional diversity of gap junction intercellular channels arising from the large number of connexin isoforms is significantly increased by heterotypic interactions between members of this family. This is particularly evident in the rectifying behavior of Cx26/Cx32 heterotypic channels (. Proc. Natl. Acad. Sci. USA. 88:8410-8414). The channel properties responsible for producing the rectifying current observed for Cx26/Cx32 heterotypic gap junction channels were determined in transfected mouse neuroblastoma 2A (N2A) cells. Transfectants revealed maximum unitary conductances (gamma(j)) of 135 pS for Cx26 and 53 pS for Cx32 homotypic channels in 120 mM KCl. Anionic substitution of glutamate for Cl indicated that Cx26 channels favored cations by 2.6:1, whereas Cx32 channels were relatively nonselective with respect to charge. In Cx26/Cx32 heterotypic cell pairs, the macroscopic fast rectification of the current-voltage relationship was fully explained at the single-channel level by a rectifying gamma(j) that increased by a factor of 2.9 as the transjunctional voltage (V(j)) changed from -100 to +100 mV with the Cx26 cell as the positive pole. A model of electrodiffusion of ions through the gap junction pore based on Nernst-Planck equations for ion concentrations and the Poisson equation for the electrical potential within the junction is developed. Selectivity characteristics are ascribed to each hemichannel based on either pore features (treated as uniform along the length of the hemichannel) or entrance effects unique to each connexin. Both analytical GHK approximations and full numerical solutions predict rectifying characteristics for Cx32/Cx26 heterotypic channels, although not to the full extent seen empirically. The model predicts that asymmetries in the conductance/permeability properties of the hemichannels (also cast as Donnan potentials) will produce either an accumulation or a depletion of ions within the channel, depending on voltage polarity, that will result in rectification. PMID:10585920

Suchyna, T M; Nitsche, J M; Chilton, M; Harris, A L; Veenstra, R D; Nicholson, B J

1999-01-01

399

Soft-Switched Single-Phase Voltage-Doubler Rectifier Using Pump Circuits  

NASA Astrophysics Data System (ADS)

Soft-switched single-phase voltage-doubler rectifier using pump circuits is presented. The active power devices in the full-bridge resonant switch are allowed to turn on and off under zero-current switching (ZCS) and zero-voltage switching (ZVS) conditions, respectively. The switching transition is mainly governed by a series resonance. The experimental prototype employing two dual-switch power modules with insulated-gate bipolar transistors is implemented to investigate the operation under the pulse-width modulation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi

400

Three-Phase Sinusoidal Rectifier Consisting of Three Thyristors and a Resonant Switch  

NASA Astrophysics Data System (ADS)

Three-phase sinusoidal rectifier consisting of three thyristors and a resonant switch is presented. The switching transition of resonant switch is mainly governed by a series resonance and this allows the thyristors to turn on and off under the zero-current switching condition. Also, the currents flowing through power devices are always limited to the dc current. The experimental prototype employing three inverter-grade thyristors and two insulated-gate bipolar transistors is implemented to investigate the operation. The results confirm that the sinusoidal input currents with a near-unity power factor can be obtained under the pulse-width modulation.

Itoh, Ryozo; Ishizaka, Kouichi

401

Soft-Switched Voltage-Doubler Sinusoidal Rectifier with Balanced Output Capacitor Voltages  

NASA Astrophysics Data System (ADS)

A novel single-phase soft-switched voltage-doubler rectifier is presented. The resonant switch cell for this has a full-bridge DC-DC converter structure built of voltage-bidirectional two-quadrant switch and has a vital function to balance the output capacitor voltages. The switching transitions are mainly governed by a series resonance. The experimental prototype employing four insulated-gate bipolar transistors is implemented to investigate the pulse-width modulated operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor under the output voltage duplication.

Itoh, Ryozo; Ishizaka, Kouichi

402

Rectifying performance and negative differential behavior in graphitechaincarbon nanotube junctions  

SciTech Connect

In this paper, the (5, 5) capped carbon nanotubes (CNTs) in contact with different lengths of sp monoatomic chains grown on the surface of graphite substrate are fabricated and its electronic transport properties sandwiched between CNT and graphite electrodes are investigated. The first-principles calculations based on nonequilibrium Green's function in combination with density-functional theory show that their rectifying performance and negative differential resistance behavior are observed under very low biases and obviously are enhanced when the length increases. From our analysis, the charge transfer, transmission spectra, projected density of states and evolutions of molecular orbitals are responsible for these phenomena.

Qiu, Ming [Department of Mechanical Engineering, University of Wisconsin, Milwaukee, Wisconsin 53211 (United States); School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Li, Jiangfan [School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Liew, K. M., E-mail: kmliew@cityu.edu.hk [Department of Civil and Architectural Engineering, City University of Hong Kong, Kowloon (Hong Kong); Yuan, Chris, E-mail: cyuan@uwm.edu [Department of Mechanical Engineering, University of Wisconsin, Milwaukee, Wisconsin 53211 (United States)

2014-01-13

403

Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.  

PubMed

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light. PMID:22319353

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-01

404

Video Article Silicon Microchips for Manipulating Cell-cell Interaction  

E-print Network

Video Article Silicon Microchips for Manipulating Cell-cell Interaction Elliot E Hui, Sangeeta N.3791/268 Citation: Hui E.E., Bhatia S.N. (2007). Silicon Microchips for Manipulating Cell-cell Interaction. JoVE. 7 Reconfigurable Culture (RC), we employ a micromachined silicon substrate with moving parts to dynamically control

Bhatia, Sangeeta

405

Electronic properties of Al xGa 1- xAs surface passivated by ultrathin silicon interface control layer  

NASA Astrophysics Data System (ADS)

The photoluminescence surface state spectroscopy (PLS 3) method was applied to a study of the surface state distribution ( NSS), effective surface recombination velocity ( Seff), electron ( EFn) and hole ( EFp) quasi-Fermi levels and band bending ( VS) on the Al 0.33Ga 0.67As surface air-exposed and passivated by the Si interface control layer (ICL) technique. Using the detailed measurements of the PL quantum efficiency for different excitation intensities, combined with the rigorous computer simulations of the bulk and surface recombination processes, the behavior and correlation among the surface characteristics under photo-excitation was determined. The present analysis indicated that forming of a Si 3N 4/Si ICL double layer (with a monolayer level control) on AlGaAs surface reduces the minimum interface state density down to 10 10 cm -2 eV -1 and surface recombination velocity to the range of 10 4 cm/s under low excitations.

Adamowicz, B.; Miczek, M.; Ikeya, K.; Mutoh, M.; Saitoh, T.; Fujikura, H.; Hasegawa, H.

1999-03-01

406

Plasmas in saline solutions sustained using rectified ac voltages: polarity and frequency effects on the discharge behaviour  

NASA Astrophysics Data System (ADS)

In this work, three major problems, namely severe electrode damage, poor plasma stability and excess power consumption, arising in ac-driven plasmas in saline solutions are solved using a rectified power source. Diagnostic studies on the effects of power source polarity and frequency on the plasma behaviour are performed. Examination of I-V characteristics and temporally resolved light emission shows that the polarity significantly influences the current amplitude when the plasma exists, while the frequency alters the bubble dynamics, which in turn affects the plasma ignition voltage. When the plasma is driven by a rectified ac power source, the electrode erosion is reduced substantially. With a low frequency, moderate applied voltage and positively rectified ac power source (e.g. 100 Hz and 350 V), a stable plasma is ignited in nearly every power cycle.

Chang, Hung-wen; Hsu, Cheng-che

2012-06-01

407

Suprachiasmatic nucleus function and circadian entrainment are modulated by G protein-coupled inwardly rectifying (GIRK) channels.  

PubMed

G protein signalling within the central circadian oscillator, the suprachiasmatic nucleus (SCN), is essential for conveying time-of-day information. We sought to determine whether G protein-coupled inwardly rectifying potassium channels (GIRKs) modulate SCN physiology and circadian behaviour. We show that GIRK current and GIRK2 protein expression are greater during the day. Pharmacological inhibition of GIRKs and genetic loss of GIRK2 depolarized the day-time resting membrane potential of SCN neurons compared to controls. Behaviourally, GIRK2 knockout (KO) mice failed to shorten free running period in response to wheel access in constant darkness and entrained more rapidly to a 6 h advance of a 12 h:12 h light-dark (LD) cycle than wild-type (WT) littermate controls. We next examined whether these effects were due to disrupted signalling of neuropeptide Y (NPY), which is known to mediate non-photic phase shifts, attenuate photic phase shifts and activate GIRKs. Indeed, GIRK2 KO SCN slices had significantly fewer silent cells in response to NPY, likely contributing to the absence of NPY-induced phase advances of PER2::LUC rhythms in organotypic SCN cultures from GIRK2 KO mice. Finally, GIRK channel activation is sufficient to cause a non-photic-like phase advance of PER2::LUC rhythms on a Per2(Luc+/-) background. These results suggest that rhythmic regulation of GIRK2 protein and channel function in the SCN contributes to day-time resting membrane potential, providing a mechanism for the fine tuning responses to non-photic and photic stimuli. Further investigation could provide insight into disorders with circadian disruption comorbidities such as epilepsy and addiction, in which GIRK channels have been implicated. PMID:25217379

Hablitz, L M; Molzof, H E; Paul, J R; Johnson, R L; Gamble, K L

2014-11-15

408

Advanced Control of a Resistance Spot Welding System  

Microsoft Academic Search

This paper deals with a middle-frequency resistance spot welding system. It consists of an input converter, welding transformer, and a full-wave rectifier mounted at the transformer secondary. The welding current at the full-wave rectifier output is normally controlled by the pulse width modulated primary voltage of the transformer supplied by the input converter. The unequal ohmic resistances of the two

Beno Klopcic; Drago Dolinar; G. Ctumberger

2008-01-01

409

Effect of sodium ferulate on delayed rectifier K+ currents in PC12 cells  

PubMed Central

In order to investigate the effect of sodium ferulate (SF) on voltage-activated K+ channels, the delayed rectifier K+ current (Ik) in PC12 rat pheochromocytoma cells was recorded using the automated patch-clamp method. The results indicated that following the application of SF, the Ik in PC12 cells was significantly decreased in a concentration-dependent manner. The analysis of activation kinetic curves and inactivation kinetic curves of Ik showed that SF had an effect on the activation and inactivation kinetics. Following the application of 15.3 ?M SF, the activation curve of the Ik of PC12 cells was shifted to positive potentials and the inactivation curve of the Ik of PC12 cells was shifted to negative potentials. This study revealed that the delayed rectifier K+ currents of PC12 cells were inhibited following SF treatment in a concentration-dependent manner. The mechanism may be associated with the delayed activation and enhanced inactivation of Ik-associated channels. PMID:25120634

WANG, WEI; WANG, YUYUN; ZHANG, CHUNLEI; SUN, MENGMENG; ZHU, XIAOYIN

2014-01-01

410

High-performance microfluidic rectifier based on sudden expansion channel with embedded block structure  

PubMed Central

A high-performance microfluidic rectifier incorporating a microchannel and a sudden expansion channel is proposed. In the proposed device, a block structure embedded within the expansion channel is used to induce two vortex structures at the end of the microchannel under reverse flow conditions. The vortices reduce the hydraulic diameter of the microchannel and, therefore, increase the flow resistance. The rectification performance of the proposed device is evaluated by both experimentally and numerically. The experimental and numerical values of the rectification performance index (i.e., the diodicity, Di) are found to be 1.54 and 1.76, respectively. Significantly, flow rectification is achieved without the need for moving parts. Thus, the proposed device is ideally suited to the high pressure environment characteristic of most micro-electro-mechanical-systems (MEMS)-based devices. Moreover, the rectification performance of the proposed device is superior to that of existing valveless rectifiers based on Tesla valves, simple nozzle/diffuser structures, or cascaded nozzle/diffuser structures. PMID:22655019

Tsai, Chien-Hsiung; Lin, Che-Hsin; Fu, Lung-Ming; Chen, Hui-Chun

2012-01-01

411

Self-contained sub-millimeter wave rectifying antenna integrated circuit  

NASA Technical Reports Server (NTRS)

The invention is embodied in a monolithic semiconductor integrated circuit in which is formed an antenna, such as a slot dipole antenna, connected across a rectifying diode. In the preferred embodiment, the antenna is tuned to received an electromagnetic wave of about 2500 GHz so that the device is on the order of a wavelength in size, or about 200 microns across and 30 microns thick. This size is ideal for mounting on a microdevice such as a microrobot for example. The antenna is endowed with high gain in the direction of the incident radiation by providing a quarter-wavelength (30 microns) thick resonant cavity below the antenna, the cavity being formed as part of the monolithic integrated circuit. Preferably, the integrated circuit consists of a thin gallium arsenide membrane overlying the resonant cavity and supporting an epitaxial Gallium Arsenide semiconductor layer. The rectifying diode is a Schottky diode formed in the GaAs semiconductor layer and having an area that is a very small fraction of the wavelength of the 2500 GHz incident radiation. The cavity provides high forward gain in the antenna and isolation from surrounding structure.

Siegel, Peter H. (Inventor)

2004-01-01

412

Conductance properties of the inwardly rectifying channel, Kir3.2: molecular and Brownian dynamics study.  

PubMed

Using the recently unveiled crystal structure, and molecular and Brownian dynamics simulations, we elucidate several conductance properties of the inwardly rectifying potassium channel, Kir3.2, which is implicated in cardiac and neurological disorders. We show that the pore is closed by a hydrophobic gating mechanism similar to that observed in Kv1.2. Once open, potassium ions move into, but not out of, the cell. The asymmetrical current-voltage relationship arises from the lack of negatively charged residues at the narrow intracellular mouth of the channel. When four phenylalanine residues guarding the intracellular gate are mutated to glutamate residues, the channel no longer shows inward rectification. Inward rectification is restored in the mutant Kir3.2 when it becomes blocked by intracellular Mg(2+). Tertiapin, a polypeptide toxin isolated from the honey bee, is known to block several subtypes of the inwardly rectifying channels with differing affinities. We identify critical residues in the toxin and Kir3.2 for the formation of the stable complex. A lysine residue of tertiapin protrudes into the selectivity filter of Kir3.2, while two other basic residues of the toxin form hydrogen bonds with acidic residues located just outside the channel entrance. The depth of the potential of mean force encountered by tertiapin is -16.1kT, thus indicating that the channel will be half-blocked by 0.4?M of the toxin. PMID:23022491

Hilder, Tamsyn A; Chung, Shin-Ho

2013-02-01

413

Temperature dependence and current transport mechanisms in AlxGa1-xN Schottky rectifiers  

NASA Astrophysics Data System (ADS)

GaN and Al0.25Ga0.75N lateral Schottky rectifiers were fabricated either with (GaN) or without (AlGaN) edge termination. The reverse breakdown voltage VB (3.1 kV for GaN; 4.3 kV for AlGaN) displayed a negative temperature coefficient of -6.00.4 V K-1 for both types of rectifiers. The reverse current originated from contact periphery leakage at moderate bias, while the forward turn-on voltage at a current density of 100 A cm-2 was 5 V for GaN and 7.5 V for AlGaN. The on-state resistances, RON, were 50 m? cm2 for GaN and 75 m? cm2 for AlGaN, producing figures-of-merit (VRB)2/RON of 192 and 246 MW cm-2, respectively. The activation energy of the reverse leakage was 0.13 eV at moderate bias.

Zhang, A. P.; Dang, G.; Ren, F.; Han, J.; Polyakov, A. Y.; Smirnov, N. B.; Govorkov, A. V.; Redwing, J. M.; Cho, H.; Pearton, S. J.

2000-06-01

414

NONLINEAR-CARRIER CONTROL FOR HIGH-POWER-FACTOR RECTIFIERS BASED ON  

E-print Network

CONVERTERS Regan Zane and Dragan MaksimoviC Power Electronics Group Department of Elect,rical and Computer based on flyback, Cuk or Sepic converters operated in the continuous conduction mode. In the NLC con, flyback, Cuk and Sepic converters offer the benefits of single-stage transformer isolation, voltage step

415

Long-term stability of neural prosthetic control signals from silicon cortical arrays in rhesus macaque motor cortex  

PubMed Central

Cortically-controlled prosthetic systems aim to help disabled patients by translating neural signals from the brain into control signals for guiding prosthetic devices. Recent reports have demonstrated reasonably high levels of performance and control of computer cursors and prosthetic limbs, but to achieve true clinical viability the long-term operation of these systems must be better understood. In particular, the quality and stability of the electrically-recorded neural signals requires further characterization. Here, we quantify action potential changes and offline neural decoder performance over 382 days of recording from 4 intracortical arrays in 3 animals. Action potential amplitude decreased by 2.4% per month on average over the course of 9.4, 10.4, and 31.7 months in 3 animals. During most time periods, decoder performance was not well correlated with action potential amplitude (p > 0.05 for 3 of 4 arrays). In two arrays from one animal, action potential amplitude declined by an average of 37% over the first 2 months after implant. However, when using simple threshold crossing events rather than well isolated action potentials, no corresponding performance loss was observed during this time using an offline decoder. One of these arrays was effectively used for online prosthetic experiments over the following year. Substantial short-term variations in waveforms were quantified using a wireless system for contiguous recording in one animal, and compared within and between days for all three animals. Overall, this study suggests that action potential amplitude declines more slowly than previously supposed, and performance can be maintained over the course of multiple years when decoding from threshold crossing events rather than isolated action potentials. This suggests that neural prosthetic systems may provide high performance over multiple years in human clinical trials. PMID:21775782

Chestek, Cynthia A.; Gilja, Vikash; Nuyujukian, Paul; Foster, Justin D.; Fan, Joline M.; Kaufman, Matthew T.; Churchland, Mark M.; Rivera-Alvidrez, Zuley; Cunningham, John P.; Ryu, Stephen I.; Shenoy, Krishna V.

2013-01-01

416

Porous silicon microcavities  

NASA Astrophysics Data System (ADS)

The properties and applications of porous silicon embedded in planar microcavity structures are investigated. The porous silicon microcavitiy (PSM) structures are based on a planar resonator formed by two narrow-band high-reflectance distributed Bragg reflectors separated by a thin active optical layer, all of which made of porous Si (p-Si) layers. The accurate control of the electrochemical dissolution of Si lets us realize p-Si multilayers with the desired refractive indeces sequence. Large improvements of the emission properties of p-Si microcavities with respect to standard p-Si samples are observed: 1) increased emission intensity, 2) spectral narrowing of the emission band, and 3) high directionality in the emission pattern. These experimental results are clarified by theoretical calculations performed with the standard transfer-matrix approach in the framework of the porous silicon quantum-box model. PSM can be used for applications in the non-linear optical field. The observed reflectivity change due to absorption saturation suggests low-treshold optical bistability in all p-Si based photonic devices.

Pellegrini, Vittorio; Tredicucci, Alessandro; Mazzoleni, Claudio; Pavesi, Lorenzo

1996-03-01

417

Silicon Investor  

NSDL National Science Digital Library

Silicon Investor, developed by go2net Inc., aims to "deliver timely, superior information" on the stock market. A team of stock analysts provide stock tips, market analysis, company reports, and breaking financial news. Additional features include commentaries on the marketplace, IPOs, earnings and government reports written by the site's regular columnists. The site also offers a portfolio tracker, an up-to-date list of stock splits, stock rating upgrades or downgrades, and an earnings calendar. Updates on the major market indices, yield curves and Reuters news can also be obtained at the site.

2000-01-01

418

Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method  

NASA Astrophysics Data System (ADS)

A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 ?m or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

Yoshiyuki Seike,; Keiji Miyachi,; Tatsuo Shibata,; Yoshinori Kobayashi,; Syuhei Kurokawa,; Toshiro Doi,

2010-06-01

419

Silicon Wafer Cleaning Using New Liquid Aerosol with Controlled Droplet Velocity and Size by Rotary Atomizer Method  

NASA Astrophysics Data System (ADS)

A liquid aerosol, which sprays cleaning liquid with a carrier gas, is widely used for cleaning semiconductor devices. The liquid aerosol using a conventional two-fluid nozzle may cause pattern damage on the wafer. To resolve this problem, we have made a prototype new rotary atomizing two-fluid cleaning nozzle (RAC nozzle), which can control the velocity distribution and size distribution of flying liquid droplets separately. It was confirmed by measuring flying liquid droplets using a shadow Doppler particle analyzer system that the mean volumetric diameter of the droplets could be atomized to 20 m or less at a rotational speed of the air turbine of 50,000 min-1 and that the mean velocity of the flying liquid droplets could be controlled in the range under 65 m/s independently. It was confirmed in a cleaning experiment using polystyrene latex (PSL) particles on a wafer that particle removal efficiency increased when shaping air pressure increased. Also, the particle removal efficiency was improved with the finer atomization promoted by a higher rotational speed of the air turbine.

Seike, Yoshiyuki; Miyachi, Keiji; Shibata, Tatsuo; Kobayashi, Yoshinori; Kurokawa, Syuhei; Doi, Toshiro

2010-06-01

420

4500 V planar implanted anode p-i-n junction rectifiers in 4H-SiC  

Microsoft Academic Search

SiC has been actively explored for high-temperature, high-voltage power electronics applications because of its wide bandgap, large avalanche electric field and high thermal conductivity. Recently, >5.5 kV epi-grown anode and 3kV aluminum-implanted anode 4H-SiC junction rectifiers have been reported. We also report a 1.1 kV junction rectifier that utilizes a deep boron implant for optimal junction leakage and a shallow

J. B. Redison; Z. Li; N. Ramungul; T. P. Chow; M. Ghezzo; J. Kretchmer; A. Elasser

1999-01-01

421

Silicon Web Process Development  

NASA Technical Reports Server (NTRS)

Progress in the development of techniques to grow silicon web at 25 wq cm/min output rate is reported. Feasibility of web growth with simultaneous melt replenishment is discussed. Other factors covered include: (1) tests of aftertrimmers to improve web width; (2) evaluation of growth lid designs to raise speed and output rate; (3) tests of melt replenishment hardware; and (4) investigation of directed gas flow systems to control unwanted oxide deposition in the system and to improve convective cooling of the web. Compatibility with sufficient solar cell performance is emphasized.

Duncan, C. S.; Seidensticker, R. G.; Hopkins, R. H.; Mchugh, J. P.; Hill, F. E.; Heimlich, M. E.; Driggers, J. M.

1978-01-01

422

Silicon sheet surface studies  

NASA Technical Reports Server (NTRS)

Several activities were performed in the area of silicon sheet surface studies. An interferometry technique was developed for measuring residual stresses in short, thin silicon sheets. Simulation of abrasion of silicon by diamond and by scrating and indentation tests was carried out. The wear rate in silicon was correlated with a wear model.

Danyluk, S.

1984-01-01

423

Silicon for photovoltaic applications  

Microsoft Academic Search

Silicon is used in photovoltaics (PV) as the starting material for monocrystalline and multicrystalline wafers as well as for thin film silicon modules. More than 90% of the annual solar cell production is based on crystalline silicon wafers. Therefore, silicon is the most important material for PV today. The challenge which the PV-industry is currently facing is to decrease the

A. Mller; M. Ghosh; R. Sonnenschein; P. Woditsch

2006-01-01

424

A Simple Control Method for High-Frequency AC Link Three-Phase AC\\/AC Converter  

Microsoft Academic Search

This paper proposes a simple control method for a high-frequency AC link three-phase AC\\/AC converter. There are three topics in this paper. First, the control strategy of the AC\\/AC converter is proposed based on a conventional rectifier and inverter system. Thus, the proposed method realizes wide control range and the high performance as same as the conventional PWM rectifier and

Daisuke Matsumura; Jun-ichi Itoh; Seiji Kondo

425

Characterization and control of crystal nucleation in amorphous electron beam evaporated silicon for thin film solar cells  

SciTech Connect

The kinetics of crystal nucleation in high-rate electron beam evaporated amorphous Si for polycrystalline thin film solar cells was systematically studied on SiN and selected ZnO:Al-coated glass substrates with dissimilar surface topographies by employing Raman spectroscopy, transmission electron microscopy, and optical microscopy. The influence of the surface topography of the substrate and the disorder of the deposited amorphous Si could be correlated to the respective characteristics of the transient and steady state regime of the nucleation rate. The steady state nucleation rate I{sub ss}, its corresponding activation energy E{sub Iss}, and consequently the size of the grains in the crystallized Si were found to be governed by the interplay between the surface roughness and the deposition temperature. The steady state nucleation rate I{sub ss} increased gradually upon increasing the substrate roughness, while lowering the deposition temperature of the amorphous Si on rough textures resulted in a decline of I{sub ss}. The time-lag {tau}, which represents a distinctive parameter for the transient regime, was only slightly affected by the substrate topography. The deposition temperature, however, had a significant influence on {tau}, with {tau} increasing by a factor of 8 upon lowering the deposition temperature from 300 to 200 deg. C for all substrate topographies. These characteristics could be correlated with the increasing structural disorder of the deposited a-Si upon decreasing the deposition temperature. Based on this analysis, we could determine design rules for the controlled preparation of large-grained poly-Si in minimized processing time on any of the used substrate types by individually adjusting the deposition temperature and implementing nucleation layers.

Sontheimer, Tobias; Scherf, Simone; Klimm, Carola; Becker, Christiane; Rech, Bernd [Helmholtz Zentrum Berlin fuer Materialien und Energie, Institute Silicon Photovoltaics, Kekulestr. 5, 12489 Berlin (Germany)

2011-09-15

426

TrkB activation by brain-derived neurotrophic factor inhibits the G protein-gated inward rectifier Kir3 by tyrosine phosphorylation of the channel.  

PubMed

G protein-activated inwardly rectifying potassium channels (Kir3) are widely expressed throughout the brain, and regulation of their activity modifies neuronal excitability and synaptic transmission. In this study, we show that the neurotrophin brain-derived neurotrophic factor (BDNF), through activation of TrkB receptors, strongly inhibited the basal activity of Kir3. This inhibition was subunit dependent as functional homomeric channels of either Kir3.1 or Kir3.4 were significantly inhibited, whereas homomeric channels composed of Kir3.2 were insensitive. The general tyrosine kinase inhibitors genistein, G 6976, and K252a but not the serine/threonine kinase inhibitor staurosporine blocked the BDNF-induced inhibition of the channel. BDNF was also found to directly stimulate channel phosphorylation because Kir3.1 immunoprecipitated from BDNF-stimulated cells showed enhanced labeling by anti-phosphotyrosine-specific antibodies. The BDNF effect required specific tyrosine residues in the amino terminus of Kir3.1 and Kir3.4 channels. Mutations of either Tyr-12, Tyr-67, or both in Kir3.1 or mutation of either Tyr-32, Tyr-53, or both of Kir3. 4 channels to phenylalanine significantly blocked the BDNF-induced inhibition. The insensitive Kir3.2 was made sensitive to BDNF by adding a tyrosine (D41Y) and a lysine (P32K) upstream to generate a phosphorylation site motif analogous to that present in Kir3.4. These results suggest that neurotrophin activation of TrkB receptors may physiologically control neuronal excitability by direct tyrosine phosphorylation of the Kir3.1 and Kir3.4 subunits of G protein-gated inwardly rectifying potassium channels. PMID:10833508

Rogalski, S L; Appleyard, S M; Pattillo, A; Terman, G W; Chavkin, C

2000-08-18

427

Advancements in silicon web technology  

NASA Technical Reports Server (NTRS)

Low defect density silicon web crystals up to 7 cm wide are produced from systems whose thermal environments are designed for low stress conditions using computer techniques. During growth, the average silicon melt temperature, the lateral melt temperature distribution, and the melt level are each controlled by digital closed loop systems to maintain thermal steady state and to minimize the labor content of the process. Web solar cell efficiencies of 17.2 pct AM1 have been obtained in the laboratory while 15 pct efficiencies are common in pilot production.

Hopkins, R. H.; Easoz, J.; Mchugh, J. P.; Piotrowski, P.; Hundal, R.

1987-01-01

428

Thin silicon solar cells  

SciTech Connect

The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

1992-12-01

429

Buried oxide layer in silicon  

DOEpatents

A process for forming Silicon-On-Insulator is described incorporating the steps of ion implantation of oxygen into a silicon substrate at elevated temperature, ion implanting oxygen at a temperature below 200.degree. C. at a lower dose to form an amorphous silicon layer, and annealing steps to form a mixture of defective single crystal silicon and polycrystalline silicon or polycrystalline silicon alone and then silicon oxide from the amorphous silicon layer to form a continuous silicon oxide layer below the surface of the silicon substrate to provide an isolated superficial layer of silicon. The invention overcomes the problem of buried isolated islands of silicon oxide forming a discontinuous buried oxide layer.

Sadana, Devendra Kumar (Pleasantville, NY); Holland, Orin Wayne (Lenoir, TN)

2001-01-01

430

The carbon nanotube-silicon heterojunction as infrared detector  

NASA Astrophysics Data System (ADS)

Carbon nanotubes are a unique material that can be either metallic or semiconducting, usually with a small bandgap inversely proportional to tube diameter and with interesting optical properties. However, their general randomness in length, diameter, and chirality, and the challenges in aggregating sufficiently large quantities of precisely uniform nanotubes, render its applications in optical detection so far unattainable beyond simple absorptive coating. The highly-ordered carbon nanotube array, as grown by the non-lithographic methods described here, surmounts many of these obstacles while presenting a geometry that is useful for focal plane array applications. A nanoporous alumina template assists the nanotube growth, which proceeds by carbon vapor deposition in a technique that is compatible with integration on silicon. We report on the experimental treatment of one possible platform for applying carbon nanotubes in infrared detection: a heterojunction photodiode with silicon. The nanotube-silicon heterojunction has rectifying characteristics that are consistent with silicon doping type, nanotube work function, and silicon-nanotube bandgaps. We investigate this hybrid nanostructure with spectral photocurrent measurements in the near and mid-infrared regime in both cooled and uncooled modes of detection. Transient photocurrent analysis suggests that both pyroelectric and direct optoelectronic effects are sources of photoresponse. First-principle theoretical treatments of nanotube-silicon heterojunction detection imply that performance parameters such as D* could be greatly optimized in future generations of samples. We explore the suitability of this detector prototype for spaceborne applications where many known properties of carbon, such as chemical and mechanical durability as well as strong covalent bonding and therefore radiation hardness, merit its consideration.

Straus, Daniel A.; Tzolov, Marian; Kuo, Teng-Fang; Yin, Aijun; Cardimona, David A.; Xu, Jimmy M.

2006-08-01

431

Automotive power generation and control  

Microsoft Academic Search

This paper describes some new developments in the application of power electronics to automotive power generation and control. A new load-matching technique is introduced that uses a simple switched-mode rectifier to achieve dramatic increases in peak and average power output from a conventional Lundell alternator, along with substantial improvements in efficiency. Experimental results demonstrate these capability improvements. Additional performance and

David J. Perreault; Vahe Caliskan

2004-01-01

432

OsKAT2 is the prevailing functional inward rectifier potassium channels in rice guard cell.  

PubMed

AtKAT1 plays roles as a major channel to uptake K(+) in guard cell when stomata open in dicot model plant Arabidopsis. In a recent publication, we isolated 3 KAT-like potassium channels in rice. We expressed them in CHO cell to identify electrophysiological characteristics of the channels. OsKAT2 showed much bigger inwardly rectifying potassium channel activities among them. The histochemical X-glu staining of transgenic rice leaf blades expressing ?-glucuronidase fused with OsKAT2 promoter showed that the OsKAT2 is dominantly expressed in rice guard cell. These findings indicate that OsKAT2 may be a functional ortholog of AtKAT1 in rice. Thus this gene will be the prime target for engineering the guard cell movement to improve drought tolerance in monocot plants, including most major crops. PMID:24103920

Hwang, Hyunsik; Yoon, Jin-Young; Cho, Hana; Kim, Beom-Gi

2013-01-01

433

Alcohol modulation of G-protein-gated inwardly rectifying potassium channels: from binding to therapeutics  

PubMed Central

Alcohol (ethanol)-induced behaviors may arise from direct interaction of alcohol with discrete protein cavities within brain proteins. Recent structural and biochemical studies have provided new insights into the mechanism of alcohol-dependent activation of G protein-gated inwardly rectifying potassium (GIRK) channels, which regulate neuronal responses in the brain reward circuit. GIRK channels contain an alcohol binding pocket formed at the interface of two adjacent channel subunits. Here, we discuss the physiochemical properties of the alcohol pocket and the roles of G protein ?? subunits and membrane phospholipid PIP2 in regulating the alcohol response of GIRK channels. Some of the features of alcohol modulation of GIRK channels may be common to other alcohol-sensitive brain proteins. We discuss the possibility of alcohol-selective therapeutics that block alcohol access to the pocket. Understanding alcohol recognition and modulation of brain proteins is essential for development of therapeutics for alcohol abuse and addiction. PMID:24611054

Bodhinathan, Karthik; Slesinger, Paul A.

2014-01-01

434

Noninvasive Surface Coverage Determination of Chemically Modified Conical Nanopores that Rectify Ion Transport  

SciTech Connect

Surface modification will change the surface charge density (SCD) at the signal-limiting region of nanochannel devices. By fitting the measured i V curves in simulation via solving the Poisson and Nernst Planck equations, the SCD and therefore the surface coverage can be noninvasively quantified. Amine terminated organosilanes are employed to chemically modify single conical nanopores. Determined by the protonation deprotonation of the functional groups, the density and polarity of surface charges are adjusted by solution pH. The rectified current at high conductivity states is found to be proportional to the SCD near the nanopore orifice. This correlation allows the noninvasive determination of SCD and surface coverage of individual conical nanopores.

Liu, Juan [Georgia State University, Atlanta; Wang, Dengchao [Georgia State University, Atlanta; Kvetny, Maksim [Georgia State University, Atlanta; Brown, Warren [Georgia State University, Atlanta; Li, Yan [Georgia State University, Atlanta; Wang, Gangli [ORNL

2012-01-01

435

Inward-rectifying potassium channelopathies: new insights into disorders of sodium and potassium homeostasis.  

PubMed

Inward-rectifying potassium (Kir) channels allow more inward than outward potassium flux when channels are open in mammalian cells. At physiological resting membrane potentials, however, they predominantly mediate outward potassium flux and play important roles in regulating the resting membrane potential in diverse cell types and potassium secretion in the kidneys. Mutations of Kir channels cause human hereditary diseases collectively called Kir channelopathies, many of which are characterized by disorders of sodium and potassium homeostasis. Studies on these genetic Kir channelopathies have shed light on novel pathophysiological mechanisms, including renal sodium and potassium handling, potassium shifting in skeletal muscles, and aldosterone production in the adrenal glands. Here, we review several recent advances in Kir channels and their clinical implications in sodium and potassium homeostasis. PMID:24899236

Cheng, Chih-Jen; Sung, Chih-Chien; Huang, Chou-Long; Lin, Shih-Hua

2015-03-01

436

Engineered specific and high-affinity inhibitor for a subtype of inward-rectifier K+ channels.  

PubMed

Inward-rectifier K(+) (Kir) channels play many important biological roles and are emerging as important therapeutic targets. Subtype-specific inhibitors would be useful tools for studying the channels' physiological functions. Unfortunately, available K(+) channel inhibitors generally lack the necessary specificity for their reliable use as pharmacological tools to dissect the various kinds of K(+) channel currents in situ. The highly conserved nature of the inhibitor targets accounts for the great difficulty in finding inhibitors specific for a given class of K(+) channels or, worse, individual subtypes within a class. Here, by modifying a toxin from the honey bee venom, we have successfully engineered an inhibitor that blocks Kir1 with high (1 nM) affinity and high (>250-fold) selectivity over many commonly studied Kir subtypes. This success not only yields a highly desirable tool but, perhaps more importantly, demonstrates the practical feasibility of engineering subtype-specific K(+) channel inhibitors. PMID:18669667

Ramu, Yajamana; Xu, Yanping; Lu, Zhe

2008-08-01

437

Rectifying Performance and Negative Differential Resistance Behavior of Doping Atoms Effect in Polyphenyls  

NASA Astrophysics Data System (ADS)

The properties of two polyphenyls doped with nitrogen and boron atoms, which are connected by an alkane chain, are investigated by the non-equilibrium Green's function method combined with the density functional theory. It has been found that the doped sites have significant effects on the current-voltage characteristics. For models with the N(B) near the alkane chain, the rectification ratio is smaller, but the rectifying performance of models with the N(B) far away from the alkane chain is tremendously enhanced and rectification ratios can reach 280, alongside negative differential resistance behavior. The mechanisms for these phenomena are explained by transmission spectra, the molecular projected self-consistent Hamiltonian eigenstates, electrostatic potential distribution, and projected density of states.

Liu, Wenjiang; Cai, Shaohong; Deng, Xiaoqing

2015-02-01

438

Delayed rectifier K channels contribute to contrast adaptation in mammalian retinal ganglion cells  

PubMed Central

SUMMARY Retinal ganglion cells adapt by reducing their sensitivity during periods of high contrast. Contrast adaptation in the firing response depends on both presynaptic and intrinsic mechanisms. Here, we investigated intrinsic mechanisms for contrast adaptation in OFF Alpha ganglion cells in the in vitro guinea pig retina. Using either visual stimulation or current injection, we show that brief depolarization evoked spiking and suppressed firing during subsequent depolarization. The suppression could be explained by Na channel inactivation, as shown in salamander cells. However, brief hyperpolarization in the physiological range (510 mV) also suppressed firing during subsequent depolarization. This suppression was sensitive selectively to blockers of delayed-rectifier K channels (KDR). Somatic membrane patches showed TEA-sensitive KDR currents with activation near ?25 mV and removal of inactivation at voltages negative to Vrest. Brief periods of hyperpolarization apparently remove KDR inactivation and thereby increase the channel pool available to suppress excitability during subsequent depolarization. PMID:21745646

Weick, Michael; Demb, Jonathan B.

2011-01-01

439

Characterization of an outward rectifying chloride current of Xenopus tropicalis oocytes.  

PubMed

Here, we describe an outward rectifying current in Xenopus tropicalis oocytes that we have called xtClC-or. The current has two components; the major component is voltage activated and independent of intracellular or extracellular Ca(2+), whereas the second is a smaller component that is Ca(2+) dependent. The properties of the Ca(2+)-independent current, such as voltage dependence and outward rectification, resemble those of ClC anion channels/transporters. This current is sensitive to NPPB and NFA, insensitive to 9AC and DIDS, and showed a whole-cell conductance sequence of SCN(-)>I(-)>Br(-)>CI(-). RT-PCR revealed the expression in oocytes of ClC-2 to ClC-7, and major reductions of current amplitudes were observed when a ClC-5 antisense oligonucleotide was injected into oocytes. The Ca(2+)-dependent component was abated after injection of 10mM BAPTA or EGTA, whereas 10mMMg(2+) inhibited the current to 263.1%. This component was blocked by 9-AC, NFA, and NPPB, whereas DIDS did not elicit any evident effect. The ion sequence selectivity was SCN=I(-)>Br(-)>Cl(-). To try to determine the molecular identity that gives rise to this component we assessed by RT-PCR the expression of the Ca(2+)-dependent Cl(-) channel TMEM16A, which was found to be present in the oocytes. However, injection of antisense TMEM16A oligonucleotides did not inhibit the transient outward current. This result fits well with the electrophysiological data. Together, these results suggest that ClC-5 is a major, but not the sole channel responsible for this outwardly rectifying Cl(-) current. PMID:23524227

Ochoa-de la Paz, Lenin David; Espino-Saldaa, Angeles Edith; Arellano-Ostoa, Rogelio; Reyes, Juan Pablo; Miledi, Ricardo; Martinez-Torres, Atalfo

2013-08-01

440

Femtosecond Laser Doped Silicon for Photovoltaic Applications  

NASA Astrophysics Data System (ADS)

Doping silicon to concentrations above the metal-insulator transition threshold yields a novel material that has potential for photovoltaic applications. By focusing femtosecond laser pulses on the surface of a silicon wafer in a sulfur hexafluoride (SF6) environment, silicon is doped with 1 % atomic sulfur. This material exhibits near-unity, broadband absorption from the visible to the near infrared (< 0.5 eV, deep below the silicon bandgap), and metallic-like conduction. These unusual optical and electronic properties suggest the formation of an intermediate band. We report on the femtosecond laser doping techniques and material properties. By changing the laser parameters and ambient environment we can control the dopant profiles, crystallinity, and surface morphology. In addition, we perform mid-infrared absorption measurements as well as temperature-dependent Hall measurements of femtosecond laser doped silicon. These two techniques could shed light on energy levels of dopant states or bands.

Sher, Meng-Ju; Lin, Yu-Ting; Winkler, M. T.; Franta, B.; Mazur, Eric

441

Laser sintering of silicon powder and carbon nanofibers for porous composite thick films  

NASA Astrophysics Data System (ADS)

We attempted the laser sintering of a mixture of waste silicon powder from silicon wafer slicing processes and carbon nanofibers. Thick films with high porosity were successfully generated by a strong combination of silicon and carbon nanofibers. The surface porosity of the thick films and the crystallinity of silicon were controllable by varying the scanning speed of the laser beam. These findings indicate the feasibility of a new fabrication method for silicon anodes for future lithium-ion batteries.

Iwabuchi, Yuki; Yan, Jiwang

2015-02-01

442

Fundamental studies and device development in beta silicon carbide. Semi-annual progress report, 1 February-31 August 1988  

SciTech Connect

The primary thrust of research of this period has been to deposit and characterize the contact materials of TaSi/sub 2/ and Al on n- and p-type material, respectively. Auger electron spectroscopy detected some oxygen throughout the thickness of these films. Current voltage characteristics were nonlinear and highly resistive due to oxygen contamination in the films. A new ultrahigh-vacuum deposition chamber is being constructed to deposit pure contacts. Rectifying contacts of gold, platinum, and PtSix were also studied. Pt surpassed Au in its rectifying properties. Ion implantation into alpha and beta silicon carbide at room temperature and 550C were also conducted. A new capacitance voltage system was purchased and commissioned.

Davis, R.F.

1988-08-31

443

New approach to purifying silicon  

NASA Technical Reports Server (NTRS)

Silicon tetrafluoride gas removes metallurgical-grade impurities when passed over silicon in quartz tube. Technique allows inexpensive increase in throughout rate. Approach could improve silicon production for silicon solar cells.

Chaney, R. E.; Ingle, W. M.; Thompson, S. W.

1980-01-01

444

Advanced SEM/EDS Analysis using Stage Control and an annular Silicon Drift Detector: Applications in Impact Studies from Centimetre below Micrometre Scale  

NASA Astrophysics Data System (ADS)

Introduction: Imaging of ever smaller structures, in situ within large samples, requires low electron beam energy (HV<6 kV) to enhance spatial resolution, and therefore also the use of low energy X-ray lines for element analysis. To separate significantly overlapping peaks e.g. N-K (392 eV) and Ti-Ll (395 eV), the incorporation of line deconvolution algorithms in energy dispersive X-ray software is of crucial importance. Methods: Without adequate X-ray count statistics, deconvolution is unlikely to be effective. We therefore used an annular Silicon Drift Detector (SDD), the Bruker XFlash 5060F which is placed between the pole piece and sample. High take-off angle and collection of X-rays from four different directions allow data collection across samples with substantial surface topography. Automated stage control and spectrum imaging allow large data sets to be acquired within a short time. Applications: (A) Large area, high resolution images (with tiling or stitching of neighbouring areas) is useful for understanding processes in the formation of tektites [1], revealing flow textures and layering, without destructive section preparation. Coalescence textures formed during the transition from melt to solid, surface pitting produced by micro-impact collisions in the impact plume, and surface etching by chemical attack in the impact plume, or later weathering, can all be revealed. (B) Spectrum imaging of the matrix in the impact melt breccia of the Chicxulub impact crater (Yaxcopoil-1 borehole, Unit 5 861.72 m) reveals secondary mineral formation, such as NaCl (<500 nm) and Fe-Ti-oxides (<150 nm) associated with garnet resorption. It documents the role of multiple episodes of precipitation of Mg-rich phyllosilicates as well as the formation and dissolution of accessory minerals in a relatively high temperature (>300C) hydrothermal event [2]. (C) In experimental hypervelocity impact craters, spectrum images readily find locations of projectile residue throughout all the complex topography. The very high count rate at even low beam energy and current reveals inhomogeneous compositions and textures below micrometre scale [3]. These results help us understand preservation and modification of structure and composition in the fine-grained cometary dust aggregates which made aluminium foil craters on the Stardust spacecraft during its encounter with comet Wild 2. Acknowledgements: International Continental Scientific Drilling Program and the Museum of Natural History Berlin for providing samples. References: [1] K.T. Howard 2011. Geological Society of London: 573-591. [2] M. Nelson et al. 2012. GCA 86: 1-20. [3] A. T. Kearsley et al. 2013. Submitted to LPSC #1910.

Salge, Tobias; Berlin, Jana; Terborg, Ralf; Howard, Kieren; Newsom, Horton; Wozniakiewicz, Penny; Price, Mark; Burchell, Mark; Cole, Mike; Kearsley, Anton

2013-04-01

445

Formation of iron disilicide on amorphous silicon  

NASA Astrophysics Data System (ADS)

Thin films of iron disilicide, ?-FeSi 2 were formed on both amorphous silicon and on crystalline silicon. The ?-phase is reported to be semiconducting with a direct band-gap of about 0.85-0.89 eV. This phase is known to form via a nucleation-controlled growth process on crystalline silicon and as a consequence a rather rough silicon/silicide interface is usually formed. In order to improve the interface a bilayer structure of amorphous silicon and iron was sequentially deposited on Czochralski <111> silicon in an e-gun evaporation system. Secondary ion mass spectrometry profiling (SIMS) and scanning electron micrographs revealed an improvement of the interface sharpness. Rutherford backscattering spectrometry (RBS) and X-ray diffractiometry showed ?-FeSi 2 formation already at 525C. It was also observed that the silicide growth was diffusion-controlled, similar to what has been reported for example in the formation of NiSi 2 for the reaction of nickel on amorphous silicon. The kinetics of the FeSi 2 formation in the temperature range 525-625C was studied by RBS and the activation energy was found to be 1.5 0.1 eV.

Erlesand, U.; stling, M.; Bodn, K.

1991-11-01

446

A nanocomposite ultraviolet photodetector based on interfacial trap-controlled charge injection.  

PubMed

Ultraviolet photodetectors have applications in fields such as medicine, communications and defence, and are typically made from single-crystalline silicon, silicon carbide or gallium nitride p-n junction photodiodes. However, such inorganic photodetectors are unsuitable for certain applications because of their high cost and low responsivity (<0.2AW(-1)). Solution-processed photodetectors based on organic materials and/or nanomaterials could be significantly cheaper to manufacture, but their performance so far has been limited. Here, we show that a solution-processed ultraviolet photodetector with a nanocomposite active layer composed of ZnO nanoparticles blended with semiconducting polymers can significantly outperform inorganic photodetectors. As a result of interfacial trap-controlled charge injection, the photodetector transitions from a photodiode with a rectifying Schottky contact in the dark, to a photoconductor with an ohmic contact under illumination, and therefore combines the low dark current of a photodiode and the high responsivity of a photoconductor (?721-1,001AW(-1)). Under a bias of <10V, our device provides a detectivity of 3.4נ10(15)Jones at 360nm at room temperature, which is two to three orders of magnitude higher than that of existing inorganic semiconductor ultraviolet photodetectors. PMID:23142945

Guo, Fawen; Yang, Bin; Yuan, Yongbo; Xiao, Zhengguo; Dong, Qingfeng; Bi, Yu; Huang, Jinsong

2012-12-01

447

Anisotropic etching of silicon  

Microsoft Academic Search

Anisotropic etching of silicon has become an important technology in silicon semiconductor processing during the past ten years. It will continue to gain stature and acceptance as standard processing technology in the next few years. Anisotropic etching of

K. E. Bean

1978-01-01

448

Advanced silicon photonic modulators  

E-print Network

Various electrical and optical schemes used in Mach-Zehnder (MZ) silicon plasma dispersion effect modulators are explored. A rib waveguide reverse biased silicon diode modulator is designed, tested and found to operate at ...

Sorace, Cheryl M

2010-01-01

449

Process for producing silicon  

DOEpatents

A process of producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

Olson, J.M.; Carleton, K.L.

1982-06-10

450

Bonding silicones with epoxies  

SciTech Connect

It is shown that silicones, both room temperature vulcanizing (RTV) and millable rubber (press cured) can be successfully bonded to other materials using plasma treatment and epoxy adhesives. The plasma treatment using dry air atmosphere increases the surface energy of the silicone and thus provides a lower water contact angle. This phenomenon allows the epoxy adhesive to wet the silicone surface and ultimately bond. Bond strengths are sufficiently high to result in failures in the silicone materials rather than the adhesive bond.

Tira, J.S.

1980-01-01

451

Silicon Wafer Epitaxy  

NSDL National Science Digital Library

This Quicktime animation shows an optional process for creating silicon epitaxial wafers. The animations shows a trichlorosilane gas being injected which creates a monocrystaline film atop the preexisting wafer. This is the seventh animation in a series of how silicon wafers are created. The previous animation showing silicon wafer polishing can be seen here.The next and final animation in this sequence about silicon wafer laser inspection can be seen here.

2009-10-19

452

Silicon-based optoelectronics  

Microsoft Academic Search

The decade of the 1990's is an opportune time for scientists and engineers to create cost-effective silicon superchips that merge silicon photonics with advanced silicon electronics on a silicon substrate. We can expect significant electrooptical devices from Column IV materials (Si, Ge, C and Sn) for a host of applications. The best devices will use strained-layer epitaxy, doped heterostructures, and

R. A. Soref

1993-01-01

453

Process for producing silicon  

DOEpatents

A process for producing silicon includes forming an alloy of copper and silicon and positioning the alloy in a dried, molten salt electrolyte to form a solid anode structure therein. An electrically conductive cathode is placed in the electrolyte for plating silicon thereon. The electrolyte is then purified to remove dissolved oxides. Finally, an electrical potential is applied between the anode and cathode in an amount sufficient to form substantially pure silicon on the cathode in the form of substantially dense, coherent deposits.

Olson, Jerry M. (Lakewood, CO); Carleton, Karen L. (Boulder, CO)

1984-01-01

454

Producing Silicon Carbide/Silicon Nitride Fibers  

NASA Technical Reports Server (NTRS)

Manufacturing process makes CxSiyNz fibers. Precursor fibers spun from extruding machine charged with polycarbosilazane resin. When pyrolyzed, resin converted to cross-linked mixture of silicon carbide and silicon nitride, still in fiber form. CxSiyNz fibers promising substitutes for carbon fibers in high-strength, low-weight composites where high electrical conductivity unwanted.

1986-01-01

455

Electrodeposition of molten silicon  

DOEpatents

Silicon dioxide is dissolved in a molten electrolytic bath, preferably comprising barium oxide and barium fluoride. A direct current is passed between an anode and a cathode in the bath to reduce the dissolved silicon dioxide to non-alloyed silicon in molten form, which is removed from the bath.

De Mattei, Robert C. (Sunnyvale, CA); Elwell, Dennis (Palo Alto, CA); Feigelson, Robert S. (Saratoga, CA)

1981-01-01

456

Silicon Wafer Polishing  

NSDL National Science Digital Library

This Quicktime animation demostrates the final polishing and cleaning processes required for creating semiconductor devices and integrated circuits. This animation is the sixth in a series of how silicon wafers are created. The previous animation showing silicon wafer lapping can be seen here. The next animation in this sequence about the optional silicon wafer epitaxy process can be seen here.

2009-10-21

457

Silicon-Integrated Optics  

Microsoft Academic Search

Summary. In this chapter, we introduce Intels research efforts and recent breakthroughs in the field of silicon photonics. We present an industrial perspective on the benefits of silicon photonics, a plan for the development of integrated devices, and the challenges involved with manufacturing these devices in high volumes. We then present an overview of Intels silicon modulator work, including design,

Mario Paniccia; Ling Liao; Ansheng Liu; Hisheng Rong; Sean Koehl

458

Effects of external Rb+ on inward rectifier K+ channels of bovine pulmonary artery endothelial cells  

PubMed Central

Inward rectifier (IR) K+ channels of bovine pulmonary artery endothelial cells were studied using the whole-cell, cell-attached, and outside-out patch-clamp configurations. The effects of Rb+ on the voltage dependence and kinetics of IR gating were explored, with [Rb+]o + [K+]o = 160 mM. Partial substitution of Rb+ for K+ resulted in voltage-dependent reduction of inward currents, consistent with Rb+ being a weakly permeant blocker of the IR. In cells studied with a K(+)- free pipette solution, external Rb+ reduced inward IR currents to a similar extent at large negative potentials but block at more positive potentials was enhanced. In outside-out patches, the single-channel i-V relationship was approximately linear in symmetrical K+, but rectified strongly outwardly in high [Rb+]o due to a reduced conductance for inward current. The permeability of Rb+ based on reversal potential, Vrev, was 0.45 that of K+, whereas the Rb+ conductance was much lower, 0.034 that of K+, measured at Vrev-80 mV. The steady state voltage- dependence of IR gating was determined in Rb(+)-containing solutions by applying variable prepulses, followed by a test pulse to a potential at which outward current deactivation was observed. As [Rb+]o was increased, the half-activation potential, V1/2, changed less than Vrev. In high [K+]o solutions V1/2 was Vrev-6 mV, while in high [Rb+]o V1/2 was Vrev + 7 mV. This behavior contrasts with the classical parallel shift of V1/2 with Vrev in K+ solutions. Steady state IR gating was less steeply voltage-dependent in high [Rb+]o than in K+ solutions, with Boltzmann slope factors of 6.4 and 4.4 mV, respectively. Rb+ decreased (slowed) both activation and deactivation rate constants defined at V1/2, and decreased the steepness of the voltage dependence of the activation rate constant by 42%. Deactivation of IR channels in outside-out patches was also slowed by Rb+. In summary, Rb+ can replace K+ in setting the voltage-dependence of IR gating, but in doing so alters the kinetics. PMID:8057077

1994-01-01

459

Identification of G protein-coupled, inward rectifier potassium channel gene products from the rat anterior pituitary gland.  

PubMed

Dopamine (DA) is a physiological regulator of PRL secretion, exerting tonic inhibitory control. DA activates an inward rectifier K(+) (IRK) channel in rat lactotropes, causing membrane hyperpolarization and inhibition of Ca(2+)-dependent action potentials. Both the activation of this effector K(+) channel and the inhibition of PRL release are mediated by D(2)-type receptor activation and pertussis toxin- sensitive G proteins. To study the molecular basis of this physiologically relevant channel, a homology-based PCR approach was employed to identify members of the IRK channel family expressed in the anterior pituitary gland. Nondegenerate primers corresponding to regions specific for IRK channels known to be G protein activated (GIRKs; gene subfamily Kir 3.0) were synthesized and used in the PCR with reverse transcribed female rat anterior pituitary messenger RNA as the template. PCR products of predicted sizes for Kir 3.1, 3.2, and 3.4 were consistently observed by ethidium bromide staining after 16 amplification cycles. The identities of the products were confirmed by subcloning and sequencing. Expression of each of these gene products in anterior pituitary was confirmed by Northern blot analysis. Functional analysis of the GIRK proteins was performed in the heterologous expression system, Xenopus laevis oocytes. Macroscopic K(+) currents were examined in oocytes injected with different combinations of Kir 3.0 complementary RNA (cRNA) and G protein subunit (beta(1)gamma(2)) cRNA. The current-voltage relationships demonstrated strong inward rectification for each individual and pairwise combination of GIRK channel subunits. Oocytes coinjected with any pair of GIRK subunit cRNA exhibited significantly larger inward K(+) currents than oocytes injected with only one GIRK channel subtype. Ligand-dependent activation of only one of the GIRK combinations (GIRK1 and GIRK4) was observed when channel subunits were coexpressed with the D(2) receptor in Xenopus oocytes. Dose-response data fit to a Michaelis-Menten equation gave an apparent K(d) similar to that for DA binding in anterior pituitary tissue. GIRK1 and GIRK4 proteins were coimmunoprecipitated from anterior pituitary lysates, confirming the presence of native GIRK1/GIRK4 oligomers in this tissue. These data indicate that GIRK1 and GIRK4 are excellent candidate subunits for the D(2)-activated, G protein-gated channel in pituitary lactotropes, where they play a critical role in excitation-secretion coupling. PMID:11416001

Gregerson, K A; Flagg, T P; O'Neill, T J; Anderson, M; Lauring, O; Horel, J S; Welling, P A

2001-07-01

460

Towards gigahertz operation: ultrafast low turn-on organic diodes and rectifiers based on C60 and tungsten oxide.  

PubMed

Ultrafast organic diodes with low turn-on voltage based on a junction between C60 and WO3 are proposed. The high electron mobility of C60 layers and the optimal work function of hexamethyldisilazane (HMDS)-treated WO3 layers together provide ideal diode characteristics including high rectification ratio and low turn-on voltage. Ultrahigh frequency (UHF) compatible rectifiers with a low voltage drop are demonstrated with the C60/WO3 diodes. PMID:21274913

Im, Dongmo; Moon, Hanul; Shin, Minchul; Kim, Joungho; Yoo, Seunghyup

2011-02-01

461

Regulation of an inwardly rectifying K channel in the T 84 epithelial cell line by calcium, nucleotides and kinases  

Microsoft Academic Search

Agonists that elevate calcium in T84 cells stimulate chloride secretion by activating KBIC, an inwardly rectifying K channel in the basolateral membrane. We have studied the regulation of this channel by calcium, nucleotides and phosphorylation using patch clamp and short-circuit current (I\\u000aSC) techniques. Open probability (P\\u000a0) was independent of voltage but declined spontaneously with time after excision. Rundown

J. A. Tabcharani; A. Boucher; J. W. L. Eng; J. W. Hanrahan

1994-01-01

462

Analysis of new step-up and step-down 18-pulse direct asymmetric autotransformer-rectifiers  

Microsoft Academic Search

This paper presents four new step-up and step-down 18-pulse direct asymmetric autotransformer rectifiers. The converters are designed to operate with variable frequency power supplies (400-800Hz), while meeting tight harmonic, power factor and output voltage requirements. The analysis takes into consideration the total number of windings used to achieve the step-up and step-down voltage gain-which determines the autotransformer structure and performance-the

Rolando P. Burgos; Alexander Uan-Zo-li; Frederic Lacaux; Arman Roshan; Fred Wang; Dushan Boroyevich

2005-01-01

463

Expression of inwardly rectifying potassium channels (GIRKs) and beta-adrenergic regulation of breast cancer cell lines  

Microsoft Academic Search

BACKGROUND: Previous research has indicated that at various organ sites there is a subset of adenocarcinomas that is regulated by beta-adrenergic and arachidonic acid-mediated signal transduction pathways. We wished to determine if this regulation exists in breast adenocarcinomas. Expression of mRNA that encodes a G-protein coupled inwardly rectifying potassium channel (GIRK1) has been shown in tissue samples from approximately 40%

Howard K Plummer III; Qiang Yu; Yavuz Cakir; Hildegard M Schuller

2004-01-01

464

A soft switching active snubber optimized for IGBT's in single switch unity power factor three-phase diode rectifiers  

Microsoft Academic Search

This paper describes a soft switching active snubber for an IGBT operating in a single switch unity power factor three-phase diode rectifier. The soft switching snubber circuit provides zero-voltage turn-off for the main switch. The high turn-off losses of the IGBT due to current tailing are reduced by zero-voltage switching. This allows the circuit to be operated at very high

Keming Chen; A. Elasser; D. A. Torrey

1995-01-01

465

Vacuum Refining of Molten Silicon  

NASA Astrophysics Data System (ADS)

Metallurgical fundamentals for vacuum refining of molten silicon and the behavior of different impurities in this process are studied. A novel mass transfer model for the removal of volatile impurities from silicon in vacuum induction refining is developed. The boundary conditions for vacuum refining systemthe equilibrium partial pressures of the dissolved elements and their actual partial pressures under vacuumare determined through thermodynamic and kinetic approaches. It is indicated that the vacuum removal kinetics of the impurities is different, and it is controlled by one, two, or all the three subsequent reaction mechanismsmass transfer in a melt boundary layer, chemical evaporation on the melt surface, and mass transfer in the gas phase. Vacuum refining experimental results of this study and literature data are used to study the model validation. The model provides reliable results and shows correlation with the experimental data for many volatile elements. Kinetics of phosphorus removal, which is an important impurity in the production of solar grade silicon, is properly predicted by the model, and it is observed that phosphorus elimination from silicon is significantly increased with increasing process temperature.

Safarian, Jafar; Tangstad, Merete

2012-12-01

466

Cloning of a Xenopus laevis Inwardly Rectifying K + Channel Subunit That Permits GIRK1 Expression of I KACh Currents in Oocytes  

Microsoft Academic Search

Xenopus oocytes injected with GIRK1 mRNA express inwardly rectifying K+ channels resembling IKACh. Yet IKACh, the atrial G proteinregulated ion channel, is a heteromultimer of GIRK1 and CIR. Reasoning that an oocyte protein might be substituting for CIR, we cloned XIR, a CIR homolog endogenously expressed by Xenopus oocytes. Coinjecting XIR and GIRK1 mRNAs produced large, inwardly rectifying K+ currents

Karen E Hedin; Nancy F Lim; David E Clapham

1996-01-01

467

Pump Characteristic based optimization of a direct water cooling system for a 10kW\\/500kHz Vienna rectifier  

Microsoft Academic Search

An ultra high power density 10-kW\\/500-kHz three-phase pulse-width modulation rectifier (Vienna Rectifier) is under development at the Power Electronic Systems Laboratory, ETH Zurich. From preliminary measurements and numerical simulations the total efficiency is assumed to be 95% at full load, resulting in power losses of up to 150 W in each multichip power module that realizes a bridge leg of

Uwe Drofenik; Gerold Laimer; Johann W. Kolar

2005-01-01

468

Design and experimental results of a 6 kW single-switch three-phase high power factor rectifier using multi-resonant zero current switching  

Microsoft Academic Search

The design and breadboard implementation of a single-switch three-phase high power factor multi-resonant rectifier delivering 147 V (DC) at 6 kW from a 3? 240 V (L-L, rms) AC input is described. This rectifier has continuous input and output currents. By the use of a multi-resonant scheme, the transistor operates with zero current switching and the diodes operate with zero

Yungtaek Jang; Robert W. Erickson

1996-01-01

469

Key concepts behind forming-free resistive switching incorporated with rectifying transport properties  

PubMed Central

This work reports the effect of Ti diffusion on the bipolar resistive switching in Au/BiFeO3/Pt/Ti capacitor-like structures. Polycrystalline BiFeO3 thin films are deposited by pulsed laser deposition at different temperatures on Pt/Ti/SiO2/Si substrates. From the energy filtered transmission electron microscopy and Rutherford backscattering spectrometry it is observed that Ti diffusion occurs if the deposition temperature is above 600C. The current-voltage (IV) curves indicate that resistive switching can only be achieved in Au/BiFeO3/Pt/Ti capacitor-like structures where this Ti diffusion occurs. The effect of Ti diffusion is confirmed by the BiFeO3 thin films deposited on Pt/sapphire and Pt/Ti/sapphire substrates. The resistive switching needs no electroforming process, and is incorporated with rectifying properties which is potentially useful to suppress the sneak current in a crossbar architecture. Those specific features open a promising alternative concept for nonvolatile memory devices as well as for other memristive devices like synapses in neuromorphic circuits. PMID:23860408

Shuai, Yao; Ou, Xin; Luo, Wenbo; Mcklich, Arndt; Brger, Danilo; Zhou, Shengqiang; Wu, Chuangui; Chen, Yuanfu; Zhang, Wanli; Helm, Manfred; Mikolajick, Thomas; Schmidt, Oliver G.; Schmidt, Heidemarie

2013-01-01

470

Cystic fibrosis gene expression is not correlated with rectifying Cl sup minus channels  

SciTech Connect

Cystic fibrosis (CF) involves a profound reduction of Cl{sup {minus}} permeability in several exocrine tissues. A distinctive, outwardly rectifying, depolarization-induced Cl{sup {minus}} channel (ORDIC channel) has been proposed to account for the Cl{sup {minus}} conductance that is defective in CF. The recently identified CF gene is predicted to code for a 1480-amino acid integral membrane protein termed the CF transmembrane conductance regulator (CFTR). The CFTR shares sequence similarity with a superfamily of ATP-binding membrane transport proteins such as P-glycoprotein and STE6, but it also has features consistent with an ion channel function. It has been proposed that the CFTR might be an ORDIC channel. To determine if CFTR and ORDIC channel expression are correlated, the authors surveyed various cell lines for natural variation in CFTR and ORDIC channel expression. In four human epithelial cell lines (T84, CaCo2, PANC-1, and 9HTEo-/S) that encompass the full observed range of CFTR mRNA levels and ORDIC channel density the authors found no correlation.

Ward, C.L.; Krouse, M.E.; Kopito, R.R.; Wine, J.J. (Stanford Univ., CA (United States)); Gruenert, D.C. (Univ. of California, San Francisco (United States))

1991-06-15

471

Anoctamin 6 is an essential component of the outwardly rectifying chloride channel  

PubMed Central

Outwardly rectifying chloride channels (ORCC, ICOR) of intermediate single-channel conductance of around 50 pS, are ubiquitously expressed, but have remained a mystery since their description more than 25 y ago. These channels have been shown to be activated on membrane excision and depolarization of the membrane voltage and by cAMP in the presence of the cystic fibrosis transmembrane conductance regulator. We show that anoctamin 6 (Ano6), a member of the recently identified family of putative Cl? channels, is the crucial component of ORCC single-channel and whole-cell currents in airway epithelial cells and Jurkat T lymphocytes. Cystic fibrosis transmembrane conductance regulator augmented ORCC produced by Ano6 in A549 airway epithelial cells. Ano6 is activated during membrane depolarization or apoptosis of Jurkat T lymphocytes and epithelial cells, and is inhibited by 5-nitro-2-(3-phenylpropylamino) benzoic acid, 4,4?-diisothio-cyanostilbene-2,2?-disulfonic acid, or AO1. Ano6 belongs to the basic equipment of any cell type, including colonic surface epithelial cells. It forms the essential component of ORCC and seems to have a role for cell shrinkage and programmed cell death. PMID:22006324

Martins, Joana Raquel; Faria, Diana; Kongsuphol, Patthara; Reisch, Barbara; Schreiber, Rainer; Kunzelmann, Karl

2011-01-01

472

Characterization of an inward rectifying cationic channel in onion guard cell vacuoles  

SciTech Connect

Ion channels modulate the large ion fluxes across the guard cell plasma membrane and tonoplast that are required for stomatal movement. In contrast to the well known ion channels at