Sample records for silicon controlled rectifier

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    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.

  2. Operation of Bidirectional Switches (DIAC) and Silicon Controlled Rectifiers (SCR) in Gamma-Radiation Environment

    SciTech Connect

    Swidan, A.M.; El-Ghanam, S.M. [Women's College for Art, Science and Education, Ain- Shams University, Helioplis, Cairo (Egypt); Soliman, F.A.S. [Nuclear Materials Authority, P.O. Box 2404, Horrya-11361, Heliopolis, Cairo (Egypt)

    2005-03-17

    Gamma-irradiation effects on the electrical parameters of the Diode AC switch (DIAC; PHI37 500) and Silicon Controlled Rectifier (SCR; 2N4444) devices have been studied in detail, where gamma-dose up to 137 x 106 rad was found to cause a serious permanent damage on their electrical characteristics. A pronounced increase in the break-over voltage (from 31.5 to 35 V), holding-current (from 13 to 53 mA) and holding voltage (from 22 to 32 V) of the DIAC is noticed. Besides, a severe decrease in the dynamic break-over voltage range (from 10 to 2.5 V) and negative resistance (from -750 to -168 ohm) is also observed. Exposing the SCRs to gamma-radiation causes their turn-on voltage and forward voltage drop values to increase from 0.8 to 2.8 V and from 1.4 to 4.5 V, respectively. Additionally, the holding current increases to 18 mA although its initial value is 3.5 mA. For the two devices, the linear dependence and high sensitivity of their electrical parameters to gamma-dose suggest the application of such devices in the field of radiation dosimetry.

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

    NASA Astrophysics Data System (ADS)

    Gourash, F.

    1984-02-01

    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.

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

    Microsoft Academic Search

    F. Gourash

    1984-01-01

    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

  5. LSI logic for phase-control rectifiers

    NASA Technical Reports Server (NTRS)

    Dolland, C.

    1980-01-01

    Signals for controlling phase-controlled rectifier circuit are generated by combinatorial logic than can be implemented in large-scale integration (LSI). LSI circuit saves space, weight, and assembly time compared to previous controls that employ one-shot multivibrators, latches, and capacitors. LSI logic functions by sensing three phases of ac power source and by comparing actual currents with intended currents.

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

    Microsoft Academic Search

    Gourash

    1984-01-01

    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

  7. Discrete-time Model Following Control of Inverter with Rectifier Load

    Microsoft Academic Search

    Atsushi Umemura; Toshimasa Haneyoshi; Yukio Saito; Fumio Harashima

    2005-01-01

    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

  8. Reverse Generator Voltage with Unidirectional Trinistor Control Rectifier

    Microsoft Academic Search

    S. J. Asseo

    1964-01-01

    Most metal mill drives use separate d-c generators for accurate speed control. Generator voltage and motor speed is controlled by an unidirectional trinistor control rectifier which supplies excitation to the generator main field. To reverse the drive, generator voltage must be reversed either by using a bias field or by connecting the trinistor in buck-boost across the single-machine field. In

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

    NASA Astrophysics Data System (ADS)

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

    1992-04-01

    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.

  10. Modelling a single phase voltage controlled rectifier using Laplace transforms

    NASA Technical Reports Server (NTRS)

    Kraft, L. Alan; Kankam, M. David

    1992-01-01

    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.

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

    Microsoft Academic Search

    John C. Salmon

    1993-01-01

    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

  12. Nonlinear PID control for three-phase PWM rectifier based on predictive current control

    Microsoft Academic Search

    Liang Ma; Fei Lin; Xiaojie You; Trillion Q. Zheng

    2008-01-01

    This paper proposes a nonlinear PID control strategy for three-phase voltage source PWM rectifier based on predictive current control. The nonlinear controller is consisted of nonlinear track differentiators (TD) and special nonlinear function of the error. It improves dc voltage response velocity, restrains overshoot and enhances robustness against load change. In addition, the sinusoidal ac current and unity power factor

  13. The Research of Three Phase Voltage PWM Rectifier Based on Variable-Structure Control

    Microsoft Academic Search

    Hua Li; Liu He; Bo Wang

    2008-01-01

    Considering the poor dynamic performance and the uncertainties of the parameters of three-phase PWM rectifiers, this paper study the mathematical model of 3-phase PWM rectifiers and proposed the sliding-mode variable structure control. It can make system quick, steady and have a robust control performance against the uncertainties of the parameters. Consequently the current wave of electricity net side is ensured

  14. Novel hybrid 12-pulse line interphase transformer boost-type rectifier with controlled output voltage

    Microsoft Academic Search

    K. Mino; G. Gong; J. W. Kolar

    2004-01-01

    This paper describes two novel hybrid 12-pulse line interphase transformer rectifier systems with integrated single-switch or two-switch boost-type output stage. The boost stage allows controlling the output voltage to a constant value independent of line voltage or output power variations. In combination with low complexity and\\/or high reliability the hybrid rectifier concept therefore is of potential interest for supplying electrically

  15. Control of Three-Phase PWM Rectifiers Using A Single DC Current Sensor

    Microsoft Academic Search

    Zhonghui Bing; Xiong Du; Jian Sun

    2011-01-01

    This paper presents a new current control method for three-phase pulse width modulation rectifiers with active power factor correction (PFC). Conventional three-phase PFC control re- quires sensing of at least two input phase currents. Since the input line must be isolated from the control circuitry, current transform- ers or Hall effects current sensors are required for sensing the phase currents,

  16. Minimization of DC Reactor and Operation Characteristics of Direct-Power-Controlled Current-Source PWM Rectifier

    E-print Network

    Fujimoto, Hiroshi

    Minimization of DC Reactor and Operation Characteristics of Direct-Power-Controlled Current characteristics of the direct power control based current-source PWM rectifier with a miniaturized DC reactor-Source PWM Rectifier Toshihiko Noguchi, Akira Sato, and Daisuke Takeuchi Nagaoka University of Technology

  17. Deadbeat controller design for a soft-switched high-frequency resonant rectifier

    Microsoft Academic Search

    Hyun Chil Choi; Chang Jun Seo

    1998-01-01

    In this paper, a deadbeat controller design technique is developed for a quantum boost series resonant rectifier (QBSRR) to achieve the fast dynamic responses of the output voltage in the presence of any load variations, and in order to monitor the load information without employing the current sensor, the load estimation method is also derived. By using the information of

  18. New current-controlled PWM rectifier-voltage source inverter without DC link components

    Microsoft Academic Search

    K. Iimori; K. Shinohara; O. Tarumi; Zixum Fu; M. Muroya

    1997-01-01

    The voltage-source inverters are normally equipped with an electrolytic capacitor in their DC link, the electrolytic capacitor has several disadvantages such as increasing size, limiting converter life and reliability. Therefore several approaches for removing the DC link capacitor have been studied. This paper proposes a new voltage source inverter without DC link components, whose rectifiers are controlled by suitable current

  19. Power regenerative controls by utilizing thyristor rectifier of voltage source inverter

    Microsoft Academic Search

    Keiju Matsui; Kazuo Tsuboi; Saburo Muto

    1992-01-01

    A novel technique of regenerative control for the voltage source inverter is described. In the proposed equipment, the rectifier bridge can be also utilized for regeneration through the medium of the DC reactor. For the other proposed type, a modified Cuk converter method is mentioned. The output current waveforms are analyzed by a new frequency analysis approach, using the switching

  20. Digital control of a Full-Bridge — Flyback isolated current rectifier with power factor correction

    Microsoft Academic Search

    Janderson Duarte; Cassiano Rech; Marcello Mezaroba; Leandro Michels

    2009-01-01

    This paper presents the modeling and control of a single-stage isolated current rectifier with power factor correction based on full-bridge and flyback topologies. The state-space averaged model of the converter for step-down and step-up operation modes is presented, as well as the design and analysis of the digital control system. Experimental results based on a 3.5 kW prototype are presented

  1. Implementation of a controlled rectifier using AC-AC matrix converter theory

    Microsoft Academic Search

    Donald G. Holmes; Thomas A. Lipo

    1992-01-01

    It is well known that a PWM-controlled rectifier can offer advantages of reduced low-order harmonics and unity input power factor when compared to a conventional thyristor converter. However, theoretically optimum PWM strategies are often difficult to implement physically or are not easily extended to regenerative operation. The authors propose an alternative PWM strategy based on AC-AC matrix converter theory, which

  2. 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...

  3. Sensorless control for a three-phase PWM rectifier-inverter system with single-chip micro-controller

    Microsoft Academic Search

    Dongsheng Li; Yasuo Notohara; Tatsuo Ando

    2009-01-01

    A three-phase PWM rectifier-inverter system for a PMSM drive with a single-chip micro-controller is presented. To reduce the cost of the system, the input\\/output currents and dc-link voltage are detected only using resistors. With the proposed sensorless control, neither an ac voltage\\/phase sensor nor a rotor speed\\/position sensor is needed in the system. All of the proposed control schemes can

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

    PubMed Central

    Lee, Hyung-Min; Ghovanloo, Maysam

    2011-01-01

    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

  5. Design and evaluation of a cellular rectifier system with distributed control

    E-print Network

    Perreault, David J.

    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 ...

  6. Sensor-less control of a half-wave rectified brushless synchronous motor

    SciTech Connect

    Oyama, Jun; Abe, Takashi; Higuchi, Tsuyoshi; Yamada, Eiji [Nagasaki Univ. (Japan). Dept. of Electrical Engineering and Computer Science; Shibahara, Kenji

    1995-12-31

    The goal of this research is to realize a complete sensorless system which can operate in whole speed range, from standstill to rated speed, using the half-wave rectified brushless synchronous motor the authors proposed as a novel servo motor. An emf with bias frequency is induced in the rotor winding of this motor by the mmf which rotates at synchronous speed and pulsates at bias frequency. The field poles are excited by the field current obtained by rectifying this emf with a diode inserted into the field winding. This motor has simple and robust brushless structure and is maintenance free. This motor also provides them with the torque control operation over the speed range from zero to the rated speed. If there is any displacement between the axis of rotating mmf and the axis of the rotor, the impedance of the field circuit varies. Therefore, the rotor position can be detected only by measuring bias frequency components of armature voltage. This method provides them with the whole sensorless control (position and speed sensorless) over the speed range from zero to the rated speed.

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

    NASA Astrophysics Data System (ADS)

    Ren, Jie; Fransson, Jonas; Zhu, Jian-Xin

    2014-06-01

    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.

  8. On Acoustic-Noise-Reduction Control Using Random Switching Technique for Switch-Mode Rectifiers in PMSM Drive

    Microsoft Academic Search

    Jui-Yuan Chai; Yeh-Hsiang Ho; Yu-Choung Chang; Chang-Ming Liaw

    2008-01-01

    This paper presents an acoustic-noise-reduction control using a random switching technique for front-end switch-mode rectifiers (SMRs) of a permanent-magnet synchronous-motor (PMSM) drive. First, the PMSM drive and its front-end ac-switch-based SMR are established. The proper controls are conducted to let the motor drive possess good driving characteristics. In the acoustic-noise-reduction control for a low-frequency SMR under a voltage closed-loop control,

  9. Improved power regenerative controls by using thyristor rectifier bridge of voltage source inverter and a switching transistor

    Microsoft Academic Search

    K. Matsui; U. Mizuno; Y. Murai

    1992-01-01

    A few improved techniques of regenerative control for the voltage source inverter are described. In the proposed equipment, the thyristor rectifier bridge can be also utilized for regeneration through a DC reactor or capacitor. For the first converter mentioned, a novel pulse-width-modulated (PWM) strategy is proposed in which the polarity of the sawtooth carrier waveforms is reversed alternately at every

  10. Characteristics of the Inward Rectifier and Its Control by pH

    Microsoft Academic Search

    MICHAEL R. BLAa-T

    Intracellular microelectrode recordings and a two-electrode voltage clamp have been used to characterize the current carried by inward rectifying K ÷ channels of stomatal guard cells from the broadbean, Vicia faba L. Superficially, the current displayed many features common to inward rectifiers of neuromuscular and egg cell membranes. In millimolar external K ÷ concentrations (K~), it activated on hyperpolarization with

  11. Combinational logic for generating gate drive signals for phase control rectifiers

    NASA Technical Reports Server (NTRS)

    Dolland, C. R.; Trimble, D. W. (inventors)

    1982-01-01

    Control signals for phase-delay rectifiers, which require a variable firing angle that ranges from 0 deg to 180 deg, are derived from line-to-line 3-phase signals and both positive and negative firing angle control signals which are generated by comparing current command and actual current. Line-to-line phases are transformed into line-to-neutral phases and integrated to produce 90 deg phase delayed signals that are inverted to produce three cosine signals, such that for each its maximum occurs at the intersection of positive half cycles of the other two phases which are inputs to other inverters. At the same time, both positive and negative (inverted) phase sync signals are generated for each phase by comparing each with the next and producing a square wave when it is greater. Ramp, sync and firing angle controls signals are than used in combinational logic to generate the gate firing control signals SCR gate drives which fire SCR devices in a bridge circuit.

  12. A soft-switched, high-frequency resonant rectifier and characteristics of the controlled system

    Microsoft Academic Search

    Hyun Chil Choi; Myung Joong Youn

    1997-01-01

    In this paper, a high frequency and soft-switched AC\\/DC rectifier employing a series-type resonant circuit is proposed to obtain the sinusoidal AC line current. Using the proposed rectifier, the high power factor and low harmonic currents are obtained in the AC line. Furthermore, several advantages such as the high power density and wide output voltage range can also be available.

  13. Rectifier cabinet static breaker

    DOEpatents

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

    1992-09-01

    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.

  14. Sensor-less control of a half-wave rectified brushless synchronous motor

    Microsoft Academic Search

    Jun OYAMA; Takashi ABE; Tsuyoshi HIGUCHI; Eiji YAMADA; Kenji SHIBAHARA

    1995-01-01

    The goal of this research is to realize a complete sensorless system which can operate in the whole speed range, from standstill to rated speed, using the “half-wave rectified brushless synchronous motor” we proposed as a novel servo motor. An EMF with bias frequency is induced in the rotor winding of this motor by the MMF which rotates at synchronous

  15. Fuzzy Control Strategy of Sub-mini Underwater Robots in Rectifying Control

    Microsoft Academic Search

    Yuyi Zhai; Liang Liu; Lei Wang; Zhenbang Gong

    2009-01-01

    In this paper, fuzzy control strategy is used to improve the stability of sub-mini underwater robots. The sub-mini underwater robots' fuzzy control method in the horizontal plane is mainly discussed here. Based on the language description of the model and according to the closed-loop system's dynamic model, the fuzzy controller language is educed with the inversion of the language model.

  16. Controlled boron doping of silicon

    Microsoft Academic Search

    Lin

    1986-01-01

    A method is described of making a semiconductor device by steps comprising doping a vertical surface of a silicon body with boron characterized in that the doping is accomplished by steps comprising: forming a layer of silicon dioxide on the vertical surface; forming a layer of silicon on the silicon dioxide on the vertical surface, and on a horizontal surface

  17. Wavelength tracking with thermally controlled silicon resonators

    E-print Network

    Mellor-Crummey, John

    of the resonant wavelength of a silicon dual-ring resonator. The feedback signal is the difference in optical-optic tuning with micro-heaters. This control scheme keeps the central wavelength of the resonator aligning, and R. Baets, "Athermal Silicon-on-insulator ring resonators by overlaying a polymer cladding

  18. Simple Diode Rectifier Circuit

    NSDL National Science Digital Library

    This website from the Thayer School of Engineering at Dartmouth College features an animation of a simple diode rectifier circuit. A rectifier is an electrical device that converts alternating current (AC) to direct current (DC), a process known as rectification.

  19. Controllable valley splitting in silicon quantum devices

    Microsoft Academic Search

    Srijit Goswami; K. A. Slinker; Mark Friesen; L. M. McGuire; J. L. Truitt; Charles Tahan; L. J. Klein; J. O. Chu; P. M. Mooney; D. W. van der Weide; Robert Joynt; S. N. Coppersmith; Mark A. Eriksson

    2007-01-01

    Silicon has many attractive properties for quantum computing, and the quantum-dot architecture is appealing because of its controllability and scalability. However, the multiple valleys in the silicon conduction band are potentially a serious source of decoherence for spin-based quantum-dot qubits. Only when a large energy splits these valleys do we obtain well-defined and long-lived spin states appropriate for quantum computing.

  20. A DSP based controller for power factor correction (PFC) in a rectifier circuit

    Microsoft Academic Search

    M. Fu; Q. Chen

    2001-01-01

    In this paper a digital signal processor (DSP) based power factor correction (PFC) scheme is presented. A dual-loop controller is designed to control the average input AC current as well as DC bus voltage. The DSP controller is implemented and tested. Design methodologies and trade-offs such as discrete-time implementation methods are also presented

  1. Analysis of single phase rectifier circuits

    NASA Astrophysics Data System (ADS)

    Lazar, James Frederick

    1997-11-01

    The preponderant application of rectifier circuits is the powering of dc loads from the ac utility line. Ordinary rectifier circuits present a nonlinear load impedance to the utility line, thereby generating harmonic currents, and contributing to the harmonic current problem. There are many active and passive rectifier circuits offering reduced harmonic currents, and in this work a methodology is developed by which these circuits may be analyzed and compared. Rectifier circuits can be classified as either active or passive. A passive rectifier circuit contains passive components (inductors, capacitors, saturable reactors, etc.), and passive switches (rectifier diodes) only. Active rectifier circuits use at least one controllable active switch (power transistor), in addition to passive switches and passive components. The performance characteristics of these circuits can be assessed with respect to a fictional device called the ideal rectifier. This assessment allows direct comparison of various approaches, passive or active, using the ideal rectifier as the common reference. Rectifier circuit performance may also be compared against specified requirements. The next topic considered is the analysis of active rectifier circuits employing a pwm (pulse width modulation) converter as a means to control power flow within the rectifier circuit. The pwm converter is modeled using the pwm switch method. A large-signal nonlinear pwm switch model is used for modeling large-signal rectifier circuit behavior, and models are developed for operation in either the continuous or discontinuous conduction mode. Similarly, a small-signal model is developed for small-signal considerations. In addition, for pwm converters operating in the continuous conduction mode, the effect of lossy resistive elements inside the converter are accounted for in the pwm switch model, and this modeling technique is shown to give results identical to those obtained via the state-space averaging method. The methods developed are then applied to the analysis of the boost rectifier operating in the discontinuous conduction mode. Three control schemes are compared, each offering a different compromise between circuit complexity and performance. Finally, a design example is given, and experimental results are provided.

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

    NASA Technical Reports Server (NTRS)

    Birchenough, A. G.

    1971-01-01

    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.

  3. EMC in power electronic devices: radiated emissions from a silicon controlled rectifier

    Microsoft Academic Search

    A. Orlandi; R. Scheich

    1994-01-01

    During the last decade, great achievements in the field of power electronics have significantly contributed to its promotion in all areas of engineering. However, its evolution to an indispensable factor in today's industrial applications has also involved a certain number of problems which have not yet been studied thoroughly or completely solved. For instance, the electromagnetic interference emanating from power

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

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

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

    PubMed Central

    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

    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

  6. Controlling Thermal Gradients During Silicon Web Growth

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Mchugh, J. P.; Skutch, M. E.; Piotrowski, P. A.

    1983-01-01

    Strategically placed slot helps to control critical thermal gradients in crucible for silicon web growth. Slot thermally isolates feed region of crucible from growth region; region where pellets are added stays hot. Heat absorbed by pellets during melting causes thermal unbalance than upsets growth conditions.

  7. Noise Properties of Rectifying Nanopores

    SciTech Connect

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

    2011-02-18

    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.

  8. Controllable low-bias negative differential resistance, switching, and rectifying behaviors of dipyrimidinyl-diphenyl induced by contact mode

    NASA Astrophysics Data System (ADS)

    Ma, Jie; Yang, Chuan-Lu; Wang, Li-Zhi; Wang, Mei-Shan; Ma, Xiao-Guang

    2014-02-01

    The negative differential resistance (NDR) and the rectifying behaviors of a molecular device induced by a saturated hydrogen atom and contact modes are investigated. Results reveal low-bias NDR behaviors of dipyrimidinyl-diphenyl (DD) molecule without saturated H atoms. NDR behavior can be eliminated depending on the contact sites. However, the rectifying behaviors of DD-molecule with saturated H atoms are apparent for all considered contact modes. In addition, the possible contact mode of the molecule in the experiment [12] was identified by examining the effect of molecular adsorption sites on gold electrodes and saturated hydrogen atom on conductance. The mechanism underlying various properties are analyzed with the highest occupied molecular orbital, lowest unoccupied molecular orbital, and transmission spectra.

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

    Microsoft Academic Search

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

    2010-01-01

    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

  10. Controllable valley splitting in silicon quantum devices

    NASA Astrophysics Data System (ADS)

    Goswami, Srijit; Slinker, K. A.; Friesen, Mark; McGuire, L. M.; Truitt, J. L.; Tahan, Charles; Klein, L. J.; Chu, J. O.; Mooney, P. M.; van der Weide, D. W.; Joynt, Robert; Coppersmith, S. N.; Eriksson, Mark A.

    2007-01-01

    Silicon has many attractive properties for quantum computing, and the quantum-dot architecture is appealing because of its controllability and scalability. However, the multiple valleys in the silicon conduction band are potentially a serious source of decoherence for spin-based quantum-dot qubits. Only when a large energy splits these valleys do we obtain well-defined and long-lived spin states appropriate for quantum computing. Here, we show that the small valley splittings observed in previous experiments on Si-SiGe heterostructures result from atomic steps at the quantum-well interface. Lateral confinement in a quantum point contact limits the electron wavefunctions to several steps, and enhances the valley splitting substantially, up to 1.5meV. The combination of electrostatic and magnetic confinement produces a valley splitting larger than the spin splitting, which is controllable over a wide range. These results improve the outlook for realizing spin qubits with long coherence times in silicon-based devices.

  11. Control of the silicon ratio in ferrosilicon production

    Microsoft Academic Search

    Helgi Thor Ingason; Gudmundur R. Jonsson

    1998-01-01

    Generalized predictive control, GPC, has been implemented in two ferrosilicon furnaces at Icelandic Alloys Ltd for controlling the silicon ratio in tapped metal. The control is based on an ARX model of the furnace. The model is used to predict the silicon ratio one and two time steps ahead. The use of GPC has resulted in decreased variations in the

  12. A New Three-Phase Rectifier for Regenerative Braking Application

    Microsoft Academic Search

    Lihua Li; Keyue Smedley; Taotao Jin

    2007-01-01

    This paper proposes a new regenerative rectifier for motor loads. The controller is implemented with simple analog components. Yet, it has the power of controlling a three-phase Voltage Source Inverter to operate either as a Power Factor Correction rectifier or as a Grid Connected Inverter according to motor's operational status. In both cases, the currents are sinusoidal. A 5 KW

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

    PubMed

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

    2014-04-01

    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

  14. Diodes and Rectifiers

    NSDL National Science Digital Library

    Kuphaldt, Tony R.

    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

  15. Current Control Method to Achieve Wide-Range Power Driving for Linear Synchronous Motor with Half-Wave-Rectified Self-Excitation

    NASA Astrophysics Data System (ADS)

    Hirayama, Tadashi; Higuchi, Tsuyoshi

    In a previous paper, we proposed a novel linear synchronous motor with half-wave-rectified self-excitation. The long-stator-type linear synchronous motor was built, and its performance was verified by performing experiments. This paper presents a new current control method for the linear synchronous motor for achieving a wide range of speeds and high-power operations. First, we propose the current control method for high-thrust operation in the constant-thrust region. This operation is realized by using a reluctance thrust resulting from the saliency of the linear synchronous motor. Furthermore, we propose a control method that maximizes the ratio of the thrust to the voltage; this method can be used to expand the operating range. Wide-range-speed operation can be achieved by applying this new control method along with field-weakening control. The thrust and operation characteristics of the proposed control methods are estimated by performing experiments and an electric and magnetic coupled analysis.

  16. What controls silicon isotope fractionation during dissolution of diatom opal?

    NASA Astrophysics Data System (ADS)

    Wetzel, F.; de Souza, G. F.; Reynolds, B. C.

    2014-04-01

    The silicon isotope composition of opal frustules from photosynthesising diatoms is a promising tool for studying past changes in the marine silicon cycle, and indirectly that of carbon. Dissolution of this opal may be accompanied by silicon isotope fractionation that could disturb the pristine silicon isotope composition of diatom opal acquired in the surface ocean. It has previously been shown that dissolution of fresh and sediment trap diatom opal in seawater does fractionate silicon isotopes. However, as the mechanism of silicon isotope fractionation remained elusive, it is uncertain whether opal dissolution in general is associated with silicon isotope fractionation considering that opal chemistry and surface properties are spatially and temporally (i.e. opal of different age) diverse. In this study we dissolved sediment core diatom opal in 5 mM NaOH and found that this process is not associated with significant silicon isotope fractionation. Since no variability of the isotope effect was observed over a wide range of dissolution rates, we can rule out the suggestion that back-reactions had a significant influence on the net isotope effect. Similarly, we did not observe an impact of temperature, specific surface area, or degree of undersaturation on silicon isotope partitioning during dissolution, such that these can most likely also be ruled out as controlling factors. We discuss the potential impacts of the chemical composition of the dissolution medium and age of diatom opal on silicon isotope fractionation during dissolution. It appears most likely that the controlling mechanism of silicon isotope fractionation during dissolution is related to the reactivity, or potentially, aluminium content of the opal. Such a dependency would imply that silicon isotope fractionation during dissolution of diatom opal is spatially and temporally variable. However, since the isotope effects during dissolution are small, the silicon isotope composition of diatom opal appears to be robust against dissolution in the deep sea sedimentary environment.

  17. Bridge Rectifier Animation

    NSDL National Science Digital Library

    This is an animation of a bridge rectifier circuit or diode bridge. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations. A link provides an optional Quicktime version of this same animation.Other 3-D Circuit Animations can be seen here.

  18. Features of Controlled Laser Thermal Cleavage of Crystalline Silicon

    SciTech Connect

    Serdyukov, A. N., E-mail: shalupaev@gsu.by; Shalupaev, S. V.; Nikityuk, Yu. V. [Gomel State University (Belarus)

    2010-11-15

    Controlled laser thermal cleavage of crystalline silicon has been numerically simulated. A 3D analysis of the thermoelastic fields formed in a single-crystal silicon wafer as a result of successive laser heating and exposure to a coolant was performed for three different versions of anisotropy. The simulation was performed for laser irradiation with different wavelengths: 1.06 and 0.808 {mu}m. The calculation results have been experimentally verified using a YAG laser. The results can be used in the electronics industry to optimize the precise separation of silicon wafers into crystals.

  19. Controllable deformation of silicon nanowires with strain up to 24%

    SciTech Connect

    Walavalkar, Sameer S.; Homyk, Andrew P.; Henry, M. David; Scherer, Axel [Department of Applied Physics, Kavli Nanoscience Institute, Caltech, 1200 E. California Blvd, Pasadena, California 91125 (United States)

    2010-06-15

    Fabricated silicon nanostructures demonstrate mechanical properties unlike their macroscopic counterparts. Here we use a force mediating polymer to controllably and reversibly deform silicon nanowires. This technique is demonstrated on multiple nanowire configurations, which undergo deformation without noticeable macroscopic damage after the polymer is removed. Calculations estimate a maximum of nearly 24% strain induced in 30 nm diameter pillars. The use of an electron activated polymer allows retention of the strained configuration without any external input. As a further illustration of this technique, we demonstrate nanoscale tweezing by capturing 300 nm alumina beads using circular arrays of these silicon nanowires.

  20. Multicell High-Current Rectifier

    Microsoft Academic Search

    Eduardo P. Wiechmann; Pablo Aqueveque; Anibal S. Morales; Pablo F. Acuand; Rolando Burgos

    2008-01-01

    A multicell rectifier (MC) structure with N + 2 redundancy is presented. The topology is based on power cells implemented with the integrated gate commuted thyristors (IGCTs) to challenge the SCR standard industry solution for the past 35 years. This rectifier is a reliable, compact, efficient, nonpolluting alternative and cost-effective solution for electrolytic applications. Its structure, based on power cells,

  1. On the use of a microwave linear accelerator for control of carrier lifetime in electronic silicon devices

    NASA Astrophysics Data System (ADS)

    Barberis, L.; Icardi, M.; Portesine, M.; Tenconi, S.; Di Marco, P. G.; Martelli, A.; Fouchi, P. G.

    The possibility of using a 12 MeV linear accelerator for control of minority carrier lifetime in silicon power rectifiers and thyristors to be used at high frequencies has been investigated. Electron irradiation of these devices has been used in place of metallic diffusion and 60Co gamma irradiation. A comparison with the latter two techniques is made. The relation between absorbed dose and high and low injection lifetimes (? HL and ? LL) has been studied for diodes and from the linear relationship {1}/{?} = {1}/{? 0} + KD found, values for the damage constant have been calculated. The dependence of the stability of the electrical characteristics of the silicon devices after electron irradiation on the annealing process at 150, 200, and 360°C has been analyzed. The conclusions drawn from this study are that charge lifetime control in semiconductors is feasible by high energy electrons because electron irradiation provides the more precise, uniform, and reproducible method of lifetime control. In addition this technique is much better than the conventional metal diffusion or gamma irradiation in raising the quality and end-product rate of these devices.

  2. Controlling the Thermal Decomposition of Silicon Carbide into Graphene

    NASA Astrophysics Data System (ADS)

    Torrance, David; Hoang, Tien; Miller, David; Zhang, Baiqian; de Heer, Walt; First, Phillip

    2011-03-01

    The quality of epitaxial graphene films grown by thermal decomposition of silicon carbide depends on experimental control of the net silicon desorption rate. Such control has been previously demonstrated by three techniques: tight confinement within an induction furnace, growth in 1-atm Ar buffer gas, or introduction of a silane overpressure. Our goal is to study the physics of these methods. We have constructed an all-graphite UHV induction furnace with maximum temperature over 1700circ; C and gas handling that allows process gas pressures from UHV to 1 atm. Sample holders with different orifices are used to vary the furnace confinement. Our initial systematic measurements of the effect of Ar buffer gas pressure establish that the silicon sublimation rate is adequately described by a 1D diffusion model with geometry-dependent parameters. Supported in part by the NSF, and the NRI-INDEX.

  3. A Battery Charge and Discharge Device Using PID Genetic Algorithm Based on PWM Rectifier

    Microsoft Academic Search

    Zhu Jun-jie; Chen Cheng; Xu Jin; Yao Ye

    2010-01-01

    The research on the application of the 3-phase high power PWM (Pulse Width Modulation) rectifier in the battery charge and discharge device has been a hotspot in the field of power electronics and control. As the traditional PID controller is difficult to achieve the optimum parameters, this paper proposes a new control method of PWM rectifier based on Genetic Algorithm

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

    Microsoft Academic Search

    Michael R. Blatt; Fiona Armstrong

    1993-01-01

    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

  5. Qubit control in phosphorus doped silicon nanowires

    NASA Astrophysics Data System (ADS)

    Gali, Adam

    2014-03-01

    Quantum confinement can turn thin silicon nanowires (SiNWs) to wide band gap material where the large surface-to-volume ratio indicates that its electronic structure may be tailored by surface termination. Here we show an example how these properties of thin SiNWs may be utilized to host quantum bits. A phosphorus (P) donor has been extensively studied in bulk silicon to realize the concept of Kane quantum computers. In most cases the quantum bit was realized as an entanglement between the donor electron spin and the nonzero nuclei spin of the donor impurity mediated by the hyperfine coupling between them. The donor ionization energies and the spin-lattice relaxation time limited the temperatures to a few kelvin in these experiments. Here, we demonstrate by means of ab initio density functional theory calculations that quantum confinement in thin SiNWs results in (i) larger excitation energies of donor impurity and (ii) a sensitive manipulation of the hyperfine coupling by external electric field. We propose that these features may allow to realize the quantum bit (qubit) experiments at elevated temperatures with a strength of electric fields applicable in current field-effect transistor technology. We also show that the strength of quantum confinement and the presence of strain induced by the surface termination may significantly affect the ground and excited states of the donors in thin SiNWs, possibly allowing an optical read-out of the electron spin. Another forms of donor-related defects as potential qubits will be also discussed.

  6. Treatment to Control Adhesion of Silicone-Based Elastomers

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  8. Research on automatic rectifying-deviation technique for drilling oil well

    Microsoft Academic Search

    Zhang Bing Yi; Luan Ju Li; Feng Gui Hong; Gu Zhao Dan

    2007-01-01

    The paper discussed an automatic rectifying- deviation system, it is a downhole closed-loop automatic device based on SCM (Single Chip Micyoco) control, whose information receive, treatment and control are absolutely accomplished under well, it represents the development direction of rectifying- deviation technology at home and abroad, with a higher level of automation. The paper mainly described the components of drilling-system

  9. Controlling the Sensing Properties of Silicon Nanowires via the Bonds Nearest to the Silicon Nanowire Surface.

    PubMed

    Halpern, Jeffrey Mark; Wang, Bin; Haick, Hossam

    2015-06-01

    Controlling the sensing properties of a silicon nanowire field effect transistor is dependent on the surface chemistry of the silicon nanowire. A standard silicon nanowire has a passive oxide layer (native oxide), which has trap states that cause sensing inaccuracies and desensitize the surface to nonpolar molecules. In this paper, we successfully modified the silicon nanowire surface with different nonoxide C3 alkyl groups, specifically, propyl (Si-CH2-CH2-CH3), propenyl (Si-CH?CH-CH3), and propynyl (Si-C?C-CH3) modifications. The effect of the near surface bond on the sensor sensitivity and stability was explored by comparing three C3 surface modifications. A reduction of trap-states led to greater sensor stability and accuracy. The propenyl-modified sensor was consistently the most stable and sensitive sensor, among the applied sensors. The propenyl- and propynyl-modified sensors consistently performed with the best accuracy in identifying specific analytes with similar polarity or similar molecular weights. A combination of features from different sensing surfaces led to the best rubric for specific analytes identification. These results indicate that nonoxide sensor surfaces are useful in identifying specific analytes and that a combination of sensors with different surfaces in a cross-reactive array can lead to specific analytes detection. PMID:25961907

  10. Controlling dopant profiles in hyperdoped silicon by modifying dopant evaporation rates during pulsed laser melting

    E-print Network

    Recht, Daniel

    We describe a method to control the sub-surface dopant profile in “hyperdoped” silicon fabricated by ion implantation and pulsed laser melting. Dipping silicon ion implanted with sulfur into hydrofluoric acid prior to ...

  11. Silicon Foils Growth by Interface-controlled Crystallization

    NASA Technical Reports Server (NTRS)

    Helmreich, D.

    1984-01-01

    During interface controlled crystallization (ICC) the chance to accelerate the removal of crystallization heat is the basis for high pulling rates of about 100 mm/min. The forced heat flow from the extended crystallization front to a cooling ramp is controlled by a lubricating melt film which also influences the crystallization behavior by suppressing nucleation centers. The basic principles of this full casting technique are presented and the influences of process parameters on the morphology of prepared silicon foils are demonstrated. Three different types of crystalline structure were found in silicon foils grown to ICC technique: dendritic, coarse granular and monocrystalline with (111) 211 orientation. The criteria for their appearance of process variables are discussed.

  12. A two-phase full-wave superconducting rectifier

    SciTech Connect

    Ariga, T.; Ishiyama, A.

    1989-03-01

    A two-phase full-wave superconducting rectifier has been developed as a small cryogenic power supply of superconducting magnets for magnetically levitation trains. Those magnets are operated in the persistent current mode. However, small ohmic loss caused at resistive joints and ac loss induced by the vibration of the train cannot be avoided. Therefore, the low-power cryogenic power supply is required to compensate for the reduction in magnet current. The presented superconducting rectifier consists of two identical full-wave rectifiers connected in series. Main components of each rectifier are a troidal shape superconducting set-up transformer and two thermally controlled switches. The test results using a 47.5 mH load magnet at 0.2 Hz and 0.5 Hz operations are described. To estimate the characteristics of the superconducting rectifier, the authors have developed a simulation code. From the experiments and the simulations, the transfer efficiency is examined. Furthermore, the optimal design of thermally controlled switches based on the finite element analysis is also discussed.

  13. A multilevel active front-end rectifier with current harmonic compensation capability

    Microsoft Academic Search

    Franco Hernández; Luis Morán; José Espinoza; Juan Dixon

    2004-01-01

    This paper presents a multilevel active front-end rectifier that can absorb current harmonics generated by nonlinear loads connected to the same power distribution bus. That is, the proposed active front-end converter can operate as an active power filter and simultaneously as a rectifier. The control scheme is simple and forces the power system line current to be sinusoidal and in

  14. Developing an automatic control system for silicon powder production line in pressing-turning method

    Microsoft Academic Search

    Xue Wendong; Zheng Dan; Chang Ling; Hong Yongqiang

    2010-01-01

    According to the technics requirements and automation control needs of silicon powder production line using pressing-turning method, it develops an automatic control system. This system is based on the principle of pressing-turning method producing silicon powder. It uses Siemens PLC and touch panel to control production line machines. The main machines are controlled by transducers. It can realize the functions

  15. Humidity sensing properties of morphology-controlled ordered silicon nanopillar

    NASA Astrophysics Data System (ADS)

    Li, Wei; Hu, Mingyue; Ge, Pengpeng; Wang, Jing; Guo, YanYan

    2014-10-01

    Ordered silicon nanopillar array (Si-NPA) was fabricated by nanosphere lithography. The size of silicon nanopillars can be easily controlled by an etching process. The period and density of nanopillar arrays are determined by the initial diameter of polystyrene (PS) spheres. It was studied as a sensing material to detect humidity. Room temperature current sensitivity of Si-NPA sensor was investigated at a relative humidity (RH) ranging from 50 to 70%. As a result, the measured current showed there was a significant increase at 70% RH. The response and recovery time was about 10 s and 15 s. These excellent sensing characteristics indicate that Si-NPA might be a practical sensing material.

  16. Nanostructured silicon membranes for control of molecular transport.

    PubMed

    Srijanto, Bernadeta R; Retterer, Scott T; Fowlkes, Jason D; Doktycz, Mitchel J

    2010-11-01

    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 and surface chemistry 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 and atomic layer 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. Functional characterization of the membranes was performed by using quantitative fluorescence microscopy to document the transport of molecular species across the membrane. PMID:24932436

  17. Controlling film growth with selective excitation: Chemical vapor deposition growth of silicon

    E-print Network

    Cohen, Philip I.

    Controlling film growth with selective excitation: Chemical vapor deposition growth of silicon Biao system of chemical vapor deposition growth of silicon. © 2004 American Institute of Physics. DOI: 10 is the silicon surface passivated by hydrogen adatoms.2 At the Si 100 surface,3 the terrace-bound hydrogen

  18. Molecular rectifiers: a new design based on asymmetric anchoring moieties.

    PubMed

    Van Dyck, Colin; Ratner, Mark A

    2015-03-11

    The quest for a molecular rectifier is among the major challenges of molecular electronics. We introduce three simple rules to design an efficient rectifying molecule and demonstrate its functioning at the theoretical level, relying on the NEGF-DFT technique. The design rules notably require both the introduction of asymmetric anchoring moieties and a decoupling bridge. They lead to a new rectification mechanism based on the compression and control of the HOMO/LUMO gap by the electrode Fermi levels, arising from a pinning effect. Significant rectification ratios up to 2 orders of magnitude are theoretically predicted as the mechanism opposes resonant to nonresonant tunneling. PMID:25706442

  19. Silicon infrared sensors for thermal comfort and control

    SciTech Connect

    Culp, C.H. (Honeywell Inc., Arlington Heights, IL (United States)); Krafthefer, B.C. (Honeywell Inc., Bloomington, MN (United States)); Rhodes, M.L.; Listvan, M.A.

    1993-04-01

    Obtaining a satisfactory comfort level is becoming increasingly important to building owners. Today, comfort control typically means using the space temperature to control space conditions. However, in the near-future, comfort control will mean measuring sensible temperature, radiant temperature, humidity and velocity, then calculating a comfort value, and controlling conditions of the space. The main factors affecting individual worker comfort are more easily measured than others. For example, radiant temperature is a relatively difficult and expensive measurement to make because of the cost of radiant sensors. Accordingly, this article describes a low cost infrared (IR) radiant sensor that is based on silicon microstructure technology. The importance of radiant temperature to comfort is also discussed.

  20. High efficiency soft-switching 3-phase PWM rectifier

    Microsoft Academic Search

    S. Sato; Y. Suehiro; S.-I. Nagai; K. Morit

    2000-01-01

    A new soft switching 3-phase PWM rectifier with simple circuit configuration and high efficiency has been developed. The proposed circuit is a kind of auxiliary resonant commutated pole (ARCP) converter. The conventional ARCP converter requires 3 auxiliary reactors and 6 auxiliary switches for the soft switching auxiliary circuit and for these switching elements, a gate drive circuit and a control

  1. Fast recovery, high voltage silicon diodes for AC motor controllers

    NASA Technical Reports Server (NTRS)

    Balodis, V.; Berman, A. H.; Gaugh, C.

    1982-01-01

    The fabrication and characterization of a high voltage, high current, fast recovery silicon diode for use in AC motor controllers, originally developed for NASA for use in avionics power supplies, is presented. The diode utilizes a positive bevel PIN mesa structure with glass passivation and has the following characteristics: peak inverse voltage - 1200 volts, forward voltage at 50 amperes - 1.5 volts, reverse recovery time of 200 nanoseconds. Characterization data for the diode, included in a table, show agreement with design concepts developed for power diodes. Circuit diagrams of the diode are also given.

  2. Low Voltage Slow Controls for the Silicon Vertex Tracker

    NASA Astrophysics Data System (ADS)

    Hammerton, Kalee

    2012-10-01

    Nuclear physics research requires the use of detectors, like the Silicon Vertex Tracker (SVT) being developed at Thomas Jefferson National Accelerator Facility, to understand the fundamental properties of particles. This detector is designed to reconstruct the paths of charged particles, aiding in the determination of their momentum. Each of the SVT's 66 individual modules is connected to a High Flex Circuit Board (HFCB). A HFCB requires 4 low voltage channels. A slow controls program was developed to control the voltage. The program allows the user to set the voltage at the 2.5 V required for the HFCB. The program is also capable of reading back the voltage and current. It includes features for real-time data monitoring and offline data analysis. The program will be expanded to control all 264 channels used for the final SVT as well as measure more parameters such as temperature and humidity.

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

    DOEpatents

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

    2009-10-13

    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.

  4. Active control of flow and heat transfer in silicon microchannels

    NASA Astrophysics Data System (ADS)

    Liu, Guohua; Xu, Jinliang; Yang, Yongping; Zhang, Wei

    2010-04-01

    Boiling heat transfer in silicon microchannels needs high walls and liquid superheats for bubble nucleation, leading to a strong thermal non-equilibrium between vapor and liquid phases, which not only damages the heat transfer device at the start-up stage, but also causes two-phase flow instabilities. In this paper, the seed bubble technique is used as an active control strategy to improve the flow and heat transfer in silicon microchannels. Seed bubbles are miniature bubbles of micron size, which are produced on a set of microheaters upstream of microchannels driven by pulse voltage signal. They flow downstream of microchannels after they depart from microheaters to decrease and control the thermal non-equilibrium between vapor and liquid phases in microchannels. The working fluid was methanol and the hydraulic diameter of the microchannels was 100 µm. The demand curves of pressure drops versus mass fluxes were examined with and without active control. Four regions (I, II, III and IV) of demand curves were identified. For the flow without active control, the four regions were the subcooled liquid flow, the superheated liquid flow, the unstable boiling flow and the vapor flow at high-vapor-mass qualities. Alternatively, for the flow with active control, the four regions were the subcooled liquid flow, the seed-bubble-triggered boiling flow, the seed-bubble-stabilized boiling flow and the vapor flow at high-vapor-mass qualities. The linear part of the demand curves is shortened when the seed bubble technique is used. The points at which the demand curves deviate from the linear part coincide into one point at different seed bubble frequencies. The seed bubbles have no influence on the subcooled liquid flow (region I) and the vapor flow at high-vapor-mass qualities (region IV). However, seed bubbles not only convert a superheated liquid flow into a quasi-stable boiling flow in region II, but also convert an unstable boiling flow into a quasi-stable boiling flow in region III. Besides, heat transfer coefficients with active control are several times those without active control in regions II and III. The higher the seed bubble frequencies, the more the heater surface temperatures decrease.

  5. 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

    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

    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

  6. Mechanical aspects of silicone coatings for hard foulant control

    Microsoft Academic Search

    Irwin L Singer; James G Kohl; Marc Patterson

    2000-01-01

    Barnacle release mechanisms and the durability of silicone coatings have been studied. Release studies were performed on both transparent, single?layer silicone coatings and duplex silicone coatings. The release forces of pseudobarnacles (epoxied studs) and Chesapeake Bay barnacles (Balanus improvisus) were measured with a pull?off (tension) tester; modes of release were revealed in video recordings of the separation process from transparent

  7. A single-phase, unity power factor, soft-switching, resonant tank boost rectifier

    Microsoft Academic Search

    Lawrence J. Borle; John C. Salmon

    1991-01-01

    A soft-switching AC to DC converter that employs a continuously resonating L-C circuit in a single-phase single-switch boost rectifier circuit is presented. The phase of the resonant tank when the switch is turned on is used as the controlling variable for shaping the rectifier input current. This phase control technique, when used together with a current estimator, is demonstrated as

  8. High Voltage Slow Controls for the Silicon Vertex Tracker

    NASA Astrophysics Data System (ADS)

    Chabwera, Minnae

    2012-10-01

    The slow controls program developed at Thomas Jefferson National Accelerator Facility, JLab, for the Silicon Vertex Tracker, SVT, controls and reports high voltage and reads back the current drawn. The SVT is a large acceptance spectrometer designed to detect charged particles and reconstruct their paths in order to determine their momentum. It consists of 66 identical modules, each of which is connected to a High Flex Circuit Board, HFCB. Each HFCB requires 2 high voltage channels. The slow controls LabVIEW program designed for the SVT allows the user to set the threshold settings at 75V required for the HFCB to operate. If the threshold settings for voltage or current are detected outside of the operating range the channel will shut-off at a ramp rate of 5V/sec to preserve the detector. The program includes features for real-time data monitoring and offline data analysis. It will be expanded to control 132 high voltage channels to be used in Hall B at JLab and will expand to measure more parameters such as temperature and humidity.

  9. Controlled growth of monolayer graphene on silicon carbide

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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.

  10. Coherent Control of a Single Silicon-29 Nuclear Spin Qubit

    E-print Network

    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

    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.

  11. Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts

    NASA Technical Reports Server (NTRS)

    Kerkar, Awdhoot V.; Henderson, Robert J. M.; Feke, Donald L.

    1990-01-01

    The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.

  12. Fabrication of precisely controlled silicon wire and cone arrays by electrochemical etching

    Microsoft Academic Search

    Hong-Seok Seo; Xiaopeng Li; Han-Don Um; Bongyoung Yoo; Jae-Hyun Kim; Kang-Pil Kim; Yong Woo Cho; Jung-Ho Lee

    2009-01-01

    There is an exponentially growing need for well-oriented, vertical silicon nano\\/micro-structure arrays, particularly in high-density integrated electronic devices. Here, we demonstrate that precisely controlled vertical arrays of silicon wires and cones can be fabricated by a combined treatment strategy of electrochemical and chemical etchings. First, a periodically ordered array of silicon wires was readily fabricated at microscale by simple electrochemical

  13. Compensator quality control with an amorphous silicon EPID.

    PubMed

    Menon, Geetha V; Sloboda, Ron S

    2003-07-01

    The calibration and quality control of compensators is conventionally performed with an ion chamber in a water-equivalent phantom. In our center, the compensator factor and four off-axis fluence ratios are measured to verify the central axis beam modulation and orientation of the compensator. Here we report the investigation of an alternative technique for compensator quality control using an amorphous silicon electronic portal imaging device (a-Si EPID). Preliminary experiments were performed to identify appropriate EPID operating parameters for this relative dosimetric study and also to quantify EPID operation. The pixel value versus energy fluence response of the EPID for both open and compensated fields was then determined, and expressed via calibration curves. For open fields the response was seen to be linear, whereas for compensated fields it exhibited a small quadratic component. To account for field size effects, we measured EPID scatter factors. These exhibited small but non-negligible dependencies on compensator thickness and source-detector distance. Finally, a number of test and clinical compensators were evaluated to assess the suitability of the EPID for compensator quality control. Our results indicate that the a-Si EPID can measure clinical compensator factors and off-axis energy fluence ratios to within 2% of values measured by a Farmer chamber on average, and so is a suitable ion chamber replacement. PMID:12906200

  14. Electric field control of donor pair diatomic molecules in silicon

    NASA Astrophysics Data System (ADS)

    Baena, Alejandra; Saraiva, Andre; Calderón, María J.; Koiller, Belita

    2015-03-01

    Single donors are well-established building blocks for engineering electronic properties of semiconductors, acting effectively as giant hydrogen atoms. Donor pairs, analogous to effective hydrogen molecules, were recently investigated in the strongly interacting regime in silicon. In this regime, electric field control renders timid results. Pairs that are more distant are more susceptible to external fields, and may harbour single electron charge control. Theoretically, the molecular quantum mechanics analogy between a donor pair and the H2 molecule in vacuum is not as straightforward as it may seem. A detailed understanding of the electronic structure of these molecular systems is a current challenge. We analyze the lowest energy states within effective mass theory, including central cell corrected donor potential effects and the conduction band multiplicity in Si. The spectrum of ionized donor pairs and its response to an external electric field will be presented. We contemplate possible advantages of heteropolar diatomic molecules, e.g, Sb -As pairs, as more efficient elements for such devices and applications.

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

    Microsoft Academic Search

    Gi-Taek Kim; T.A. Lipo

    1995-01-01

    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

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

    Microsoft Academic Search

    Gi-Taek Kim; Thomas A. Lipo

    1996-01-01

    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,

  17. Microstructural control of silicon carbide via liquid phase sintering

    NASA Astrophysics Data System (ADS)

    Mrotek, Sharon Robinson

    Silicon carbide ceramics with various microstructures were fabricated by controlling the amount and composition of a Y2O3-Al 2O3 liquid phase, crystallographic phase of the starting powders, trace impurities in those powders, and time and temperature of sintering and post- sintering heat-treatments. Alpha and beta SiC "seeds" were used to control grain growth during sintering. The grain size distribution and aspect ratio of the grains were determined through microstructural analysis of polished and etched samples. TEM was used in conjunction with EDS to determine the distribution of the sintering aids in the grains and the grain boundaries. Additionally, the final phase content of the samples was determined via x-ray diffraction. The fracture toughness and hardness were measured to evaluate the relative effects of the microstructural variations on the mechanical properties. Alpha silicon carbide samples exhibited a fine grained, equiaxed microstructure. Under appropriate conditions, samples prepared from beta-SiC powders underwent a phase transformation to alpha-SiC accompanied by the growth of elongated platelet grains. The addition of alpha seeds to the beta powder reduced the size of the platelets compared to unseeded samples of the same composition. If the beta to alpha phase transformation did not occur, the beta samples developed an equiaxed microstructure. The grain size of all samples decreased with increasing amounts of sintering additives. The beta to alpha phase transformation, required to obtain an elongated grain microstructure, was catalyzed by the presence of sufficient amounts of aluminum. If insufficient Al impurity was present in the powder, purposeful additions of Al metal could induce the phase transformation. Examination of the sintering progression over time indicated that the phase transformation occurred late in the sintering process and appeared to occur via a solution/reprecipitation mechanism. Post-sintering heat treatments were also used to encourage the beta to alpha phase transformation. However, the heat treatments were accompanied by high weight loss and volatilization of significant amounts of alumina from the liquid phase. Since fracture toughness was a function of the final grain morphology, the formation of large interlocking platelets was critical in obtaining the desired high toughness values.

  18. Noise-compensating pulses for electrostatically controlled silicon spin qubits

    E-print Network

    Xin Wang; Fernando A. Calderon-Vargas; Muhed S. Rana; Jason P. Kestner; Edwin Barnes; Sankar Das Sarma

    2014-10-21

    We study the performance of SUPCODE---a family of dynamically correcting pulses designed to cancel simultaneously both Overhauser and charge noise for singlet-triplet spin qubits---adapted to silicon devices with electrostatic control. We consider both natural Si and isotope-enriched Si systems, and in each case we investigate the behavior of individual gates under static noise and perform randomized benchmarking to obtain the average gate error under realistic 1/f noise. We find that in most cases SUPCODE pulses offer roughly an order of magnitude reduction in gate error, and especially in the case of isotope-enriched Si, SUPCODE yields gate operations of very high fidelity. We also develop a version of SUPCODE that cancels the charge noise only, "$\\delta J$-SUPCODE", which is particularly beneficial for isotope-enriched Si devices where charge noise dominates Overhauser noise, offering a level of error reduction comparable to the original SUPCODE while yielding gate times that are 30% to 50% shorter. Our results show that the SUPCODE noise-compensating pulses provide a fast, simple, and effective approach to error suppression, bringing gate errors well below the quantum error correction threshold in principle.

  19. Hexagram Rectifier—Active Front End of Hexagram Inverter for Medium-Voltage Variable-Speed Drives

    Microsoft Academic Search

    Jun Wen; Keyue Smedley

    2008-01-01

    Recently, a new multilevel inverter-hexagram inverter has been reported for medium-voltage (MV) variable-speed drives (VSDs). This paper will propose a hexagram rectifier as the active front end for the hexagram-based MV VSD systems. The control of the hexagram rectifier is based on one-cycle control-an excellent control scheme for switching power converters. With the proposed control scheme, unity power factor at

  20. A boron nitride nanotube peapod thermal rectifier

    NASA Astrophysics Data System (ADS)

    Loh, G. C.; Baillargeat, D.

    2014-06-01

    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 heat—the 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.

  1. A boron nitride nanotube peapod thermal rectifier

    SciTech Connect

    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

    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 heat—the 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.

  2. Control of carbon balance in a silicon smelting furnace

    DOEpatents

    Dosaj, V.D.; Haines, C.M.; May, J.B.; Oleson, J.D.

    1992-12-29

    The present invention is a process for the carbothermic reduction of silicon dioxide to form elemental silicon. Carbon balance of the process is assessed by measuring the amount of carbon monoxide evolved in offgas exiting the furnace. A ratio of the amount of carbon monoxide evolved and the amount of silicon dioxide added to the furnace is determined. Based on this ratio, the carbon balance of the furnace can be determined and carbon feed can be adjusted to maintain the furnace in carbon balance.

  3. Controlling carbon nanotube photoluminescence using silicon microring resonators

    NASA Astrophysics Data System (ADS)

    Noury, Adrien; Le Roux, Xavier; Vivien, Laurent; Izard, Nicolas

    2014-05-01

    We report on coupling between semiconducting single-wall carbon nanotubes (s-SWNT) photoluminescence and silicon microring resonators. Polyfluorene extracted s-SWNT deposited on such resonators exhibit sharp emission peaks, due to interaction with the cavity modes of the microring resonators. Ring resonators with radius of 5 ?m and 10 ?m were used, reaching quality factors up to 4000 in emission. These are among the highest values reported for carbon nanotubes coupled with an integrated cavity on silicon platform, which open up the possibility to build s-SWNT based efficient light source on silicon.

  4. Controlling carbon nanotube photoluminescence using silicon microring resonators.

    PubMed

    Noury, Adrien; Le Roux, Xavier; Vivien, Laurent; Izard, Nicolas

    2014-05-30

    We report on coupling between semiconducting single-wall carbon nanotubes (s-SWNT) photoluminescence and silicon microring resonators. Polyfluorene extracted s-SWNT deposited on such resonators exhibit sharp emission peaks, due to interaction with the cavity modes of the microring resonators. Ring resonators with radius of 5 ?m and 10 ?m were used, reaching quality factors up to 4000 in emission. These are among the highest values reported for carbon nanotubes coupled with an integrated cavity on silicon platform, which open up the possibility to build s-SWNT based efficient light source on silicon. PMID:24787283

  5. Multi-Cell High-Current Rectifier

    Microsoft Academic Search

    E. P. Wiechmann; P. E. Aqueveque; A. S. Morales; P. F. Acuna; R. P. Burgos

    2006-01-01

    A multi-cell rectifier (MC) structure is presented. The topology is based on power cells implemented with IGCTs thus replacing the SCR standard industry solution for the past 35 years. This rectifier is a reliable, compact, efficient, non-polluting alternative and cost effective solution for electrolytic applications. It injects quasi-sinusoidal input currents and provides unity power factor without the use of passive

  6. Geometry control of recrystallized silicon wafers for solar applications

    E-print Network

    Ruggiero, Christopher W

    2009-01-01

    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 ...

  7. Evaporation of silicon nanoparticles under scanning tunneling microscope control

    NASA Astrophysics Data System (ADS)

    Hager, Michaela; Berezin, Alexander S.; Zinkicheva, Tamara T.; Bohme, Diethard K.; Probst, Michael; Scheier, Paul; Nazmutdinov, Renat R.

    2013-11-01

    A kinetic model is developed to describe the heating and evaporation of a spherical nanoparticle under the influence of a scanning tunneling microscope (STM). Simulations were performed for silicon nanoparticles of different sizes and for different STM parameters. Different kinetic features of evaporation are predicted and discussed. The lifetime of the nanoparticles is estimated and compared with original experimental data obtained for layers of silicon nanoparticles formed upon magnetron sputtering and deposited on a highly oriented pyrolytic graphite surface (HOPG).

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    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 1H 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.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 1H 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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10458f

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

    DOEpatents

    Carlson, David E. (Yardley, PA)

    1980-01-01

    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.

  10. Electron beam quality control using an amorphous silicon EPID

    SciTech Connect

    Beck, J. A.; Budgell, G. J.; Roberts, D. A.; Evans, P. M. [North Western Medical Physics, Christie Hospital NHS Foundation Trust, Withington, Manchester M20 4BX (United Kingdom); Joint Department of Physics, Institute of Cancer Research, Royal Marsden NHS Foundation Trust, Downs Road Sutton, Surrey SM2 5PT (United Kingdom)

    2009-05-15

    An amorphous silicon EPID has been investigated to determine whether it is capable of quality control constancy measurements for linear accelerator electron beams. The EPID grayscale response was found to be extremely linear with dose over a wide dose range and, more specifically, for exposures of 95-100 MU. Small discrepancies of up to 0.8% in linearity were found at 6 MeV (8-15 MeV showed better agreement). The shape of the beam profile was found to be significantly altered by scatter in air over the approximately 60 cm gap between the end of the applicator and the EPID. Nevertheless, relative changes in EPID-measured profile flatness and symmetry were linearly related to changes in these parameters at 95 cm focus to surface distance (FSD) measured using a 2D diode array. Similar results were obtained at 90 deg. and 270 deg. gantry angles. Six months of daily images were acquired and analyzed to determine whether the device is suitable as a constancy checker. EPID output measurements agreed well with daily ion chamber measurements, with a 0.8% standard deviation in the difference between the two measurement sets. When compared to weekly parallel plate chamber measurements, this figure dropped to 0.5%. A Monte Carlo (MC) model of the EPID was created and demonstrated excellent agreement between MC-calculated profiles in water and the EPID at 95 and 157 cm FSD. Good agreement was also found with measured EPID profiles, demonstrating that the EPID provides an accurate measurement of electron profiles. The EPID was thus shown to be an effective method for performing electron beam daily constancy checks.

  11. Controls on silicon cycling in Southeast Asian rice production systems

    NASA Astrophysics Data System (ADS)

    Klotzbücher, Thimo; Marxen, Anika; Vetterlein, Doris; Jahn, Reinhold

    2013-04-01

    Recent research suggests that silicon (Si) is beneficial for rice plants, i.e., a sufficient Si supply improves their resistance against pests and pathogens and increases the uptake of essential nutrients. Despite its potential importance for rice yields, cycling of Si in rice production systems is poorly studied. We assess plant-available Si (Sipa; determined using acetate extraction) in topsoils (Ap+Arp horizons) and Si uptake by plants at 70 paddy fields managed by local farmers in contrasting regions of Vietnam and the Philippines. First results show that Sipa contents are considerably larger in Philippine (217 ± 100 mg Sipa kg-1 ) than in Vietnamese (32 ± 19 mg Sipa kg-1) paddy soils. Rice straw from the Philippines contains 8.6 ± 0.9 % Si, straw from Vietnam 5.0 ± 1.2 % Si. Laboratory experiments showed that Si is limiting the growth of rice plants in some of the Vietnamese soils. We assume that differences in geo-/ pedologic conditions between Vietnam and the Philippines explain the data. Large Sipa contents in the Philippine soils are due to recent rock formation by active volcanism, hence, by a large Sipa input due to mineral weathering in recent geologic history. In contrast, parent materials of the Vietnamese paddy soils derive from old and highly weathered land surfaces. Hence, our data suggest that geo-/pedologic conditions are the main control for the availability of Si in paddy soils. Currently, we examine the relevance of agricultural practices for small-scale differences in the availability of Si within regions. Inadequate practices, such as removal of rice straw from the fields, might deplete Sipa in paddy soils causing a decrease in rice yields in some regions of Vietnam. We investigate the role of phytoliths (amorphous Si bodies contained in rice straw) as source of Sipa in paddy soils. Our methods include laboratory experiments and the assessment of turnover times of phytoliths in paddy soils; first results will be presented and discussed at the EGU conference.

  12. 46 CFR 129.360 - Semiconductor-rectifier systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360 Shipping...ELECTRICAL INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each...

  13. Size controlled synthesis of silicon nanocrystals using cationic surfactant templates.

    PubMed

    Linehan, Keith; Doyle, Hugh

    2014-02-12

    Alkyl-terminated silicon nanocrystals (Si NCs) are synthesized at room temperature by hydride reduction of silicon tetrachloride (SiCl?) within inverse micelles. Highly monodisperse Si nanocrystals with average diameters ranging from 2 to 6 nm are produced by variation of the cationic quaternary ammonium salts used to form the inverse micelles. Transmission electron microscopy imaging shows that the NCs are highly crystalline, while FTIR spectra confirm that the NCs are passivated by covalent attachment of alkanes, with minimal surface oxidation. UV-vis absorbance and photoluminescence spectroscopy show significant quantum confinement effects, with moderate absorption in the UV spectral range, and a strong blue emission with a marked dependency on excitation wavelength. The photoluminescence quantum yield (?) of the Si NCs exhibits an inverse relationship with the mean NC diameter, with a maximum of 12% recorded for 2 nm NCs. PMID:24027115

  14. Novel plasma control method in PECVD for preparing microcrystalline silicon

    SciTech Connect

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

    1997-07-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Wang, Chenlei

    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.

  16. 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

    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

    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.

  17. 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)

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

    2012-11-01

    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.

  18. Development of high speed rectifier diodes

    NASA Astrophysics Data System (ADS)

    Tamura, Takashi; Uesugi, Masato; Nakajima, Masato

    1992-08-01

    An overview of high speed rectifier diode development is presented. Chip design as a consequence of the type change to planar type and review on gold dispersion condition to get higher speed chips were conducted. A review was conducted on mounting to the package and wire bonding. Evaluation samples at three levels were trial produced and their design evaluation test was started.

  19. CONTROLLED MOLECULAR ADSORPTION ON SILICON: Laying a Foundation for Molecular Devices

    NASA Astrophysics Data System (ADS)

    Wolkow, Robert A.

    1999-10-01

    This review is about understanding and controlling organic molecular adsorption on silicon. The goal is to provide a microscopic picture of structure and bonding in covalently attached molecule-silicon surface systems. The bias here is that an unprecedented, detailed understanding of adsorbate-surface structures is required in order to gain the control necessary to incorporate organic function into existing technologies or, eventually, to make new molecule-scale devices. A discussion of recent studies of adsorbate structure is presented. This includes simple alkenes, polyenes, benzene, and carene adsorbed on Si(100). Also included is a discussion of wet chemical procedures for forming alkyl and alkoxy covalently functionalized silicon. These discussions are presented together with comments on the related issues of adsorption dynamics and nano-scale manipulation in an effort to point the way toward principles and procedures that will allow the hybrid properties of organic molecules and surfaces to be harnessed.

  20. D0 Silicon Upgrade: Control Dewar Valve Calculations

    SciTech Connect

    Rucinski, Russ; /Fermilab

    1995-10-20

    This engineering note documents the calculations that were done to support the valve size selection for the magnet flow control valve, EVMF in the solenoid control dewar. The size selected was a control valve with a Cv = 0.32.

  1. Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean

    E-print Network

    Paris-Sud XI, Université de

    Southern Ocean control of silicon stable isotope distribution in the deep Atlantic Ocean Gregory F distribution in the deep Atlantic Ocean from Denmark Strait to Drake Passage, documenting strong meridional sources of deep and bottom waters in the Atlantic Ocean: waters of North Atlantic and Nordic origin carry

  2. Deposition of controllable preferred orientation silicon films on glass by inductively coupled plasma chemical vapor deposition

    Microsoft Academic Search

    Junshuai Li; Jinxiao Wang; Min Yin; Pingqi Gao; Deyan He; Qiang Chen; Yali Li; Hajime Shirai

    2008-01-01

    An inductively coupled plasma (ICP) system with the adjustable distance between the inductance coil and substrates was designed to effectively utilize the spatial confinement of ICP discharge, and then control the gas-phase transport process. The effects of the gas phase processes on the crystallinity and preferred orientation of silicon films deposited on glass were systematically investigated. The investigation was conducted

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  4. EFFECT OF CAST RECTIFIERS ON THE MARGINAL FIT OF UCLA ABUTMENTS

    PubMed Central

    Jaime, Ana Paula Gumieiro; de Vasconcellos, Diego Klee; Mesquita, Alfredo Mikail Melo; Kimpara, Estevão Tomomitsu; Bottino, Marco Antonio

    2007-01-01

    Objectives: This study assessed the effect of cast rectifiers on the marginal misfit of cast UCLA abutments compared to premachined UCLA abutments. The influence of casting and porcelain baking on the marginal misfit of these components was also investigated. Methods: Two groups were analyzed: test group – 10 cast UCLA abutments, finished with cast rectifier and submitted to ceramic application; control group – 10 premachined UCLA abutments, cast with noble metal alloy and submitted to ceramic application. Vertical misfit measurements were performed under light microscopy. In the test group, measurements were performed before and after the use of cast rectifiers, and after ceramic application. In the control group, measurements were performed before and after casting, and after ceramic application. Data were submitted to statistical analysis by ANOVA and Tukey's test (?= 5%). Results: The use of cast rectifiers significantly reduced the marginal misfit of cast UCLA abutments (from 25.68?m to 14.83?m; p<0.05). After ceramic application, the rectified cylinders presented misfit values (16.18?m) similar to those of premachined components (14.3 ?m). Casting of the premachined UCLA abutments altered the marginal misfit of these components (from 9.63 ?m to 14.6 ?m; p<0.05). There were no significant changes after porcelain baking, in both groups. Conclusion: The use of cast rectifiers reduced the vertical misfit of cast UCLA abutments. Even with carefully performed laboratory steps, changes at the implant interface of premachined UCLA abutments occurred. Ceramic application did not alter the marginal misfit values of UCLA abutments. PMID:19089125

  5. pH-controlled silicon nanowires fluorescence switch

    NASA Astrophysics Data System (ADS)

    Mu, Lixuan; Shi, Wensheng; Zhang, Taiping; Zhang, Hongyan; She, Guangwei

    2010-08-01

    Covalently immobilizing photoinduced electronic transfer (PET) fluorophore 3-[N, N-bis(9-anthrylmethyl)amino]-propyltriethoxysilane (DiAN) on the surface of silicon nanowires (SiNWs) resulted a SiNWs-based fluorescence switch. This fluorescence switch is operated by adjustment of the acidity of the environment and exhibits sensitive response to pH at the range from 8 to 10. Such response is attributed to the effect of pH on the PET process. The successful combination of logic switch and SiNWs provides a rational approach to assemble different logic molecules on SiNWs for realization of miniaturization and modularization of switches and logic devices.

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

    NASA Astrophysics Data System (ADS)

    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; Janzén, Erik; Wrachtrup, Jörg

    2015-02-01

    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.

  7. Hexagram rectifier - Active front end of hexagram inverter for medium voltage variable speed drives

    Microsoft Academic Search

    Jun Wen; Keyue Ma Smedley

    2008-01-01

    Hexagram Inverter that built from six standard three-phase two-level voltage source converters (VSCs) has been proposed recently for medium voltage adjustable speed drive applications. It has the advantages of modular structure, no voltage unbalance, easy control, low voltage stress and low DC energy storage etc. This paper will propose the hexagram rectifier as the active front end for the hexagram

  8. A novel ZVT three-phase rectifier\\/inverter with reduced auxiliary switch stresses and losses

    Microsoft Academic Search

    Qiong Li; Xunwei Zhou; Fred C. Lee

    1996-01-01

    A novel, space vector modulated, zero-voltage-transition, three-phase boost rectifier\\/voltage source inverter with coupled inductors in the auxiliary circuit is proposed. The ZVT operation of the power converter is accomplished by the use of a low power rating auxiliary circuit. The ZCS operation in auxiliary switches is also achieved with a new control scheme

  9. Six Unimolecular Rectifiers and What Lies Ahead

    Microsoft Academic Search

    Robert M. Metzger

    Six unimolecular rectifiers are discussed: ?-hexadecylquinolinium tricyanoquinodimethanide, 1, and two thioacetyl derivatives of 1, namely (Z)- ?-cyano-?-[N-tetradecylthioacetylquinolin-4-ylium)-4-styryl-dicyanomethanide, 2, and (Z)-?-cyano-?-[N-hexadecylthioacetylquinolin-4-ylium)-4-styryl-dicyanomethanide, 3, and three other rectifiers of very different structure: 2,6-di[dibutylaminophenylvinyl]- 1-butylpyridinium iodide, 4, dimethylanilino-aza[C60]-fullerene, 5, and fullerene-bis-[4-diphenylamino-4”-(N-ethyl-N-2” ’-ethyl)amino-1,4-diphenyl-1,3-butadiene] malonate, 6. Monolayers of these molecules exhibit asymmetric electrical conductivity between Au or Al electrodes. We also suggest approaches\\u000a towards one-molecule electronic

  10. Laserlike vibrational instability in rectifying molecular conductors.

    PubMed

    Lü, Jing-Tao; Hedegård, Per; Brandbyge, Mads

    2011-07-22

    We study the damping of molecular vibrations due to electron-hole pair excitations in donor-acceptor (D-A) type molecular rectifiers. At finite voltage additional nonequilibrium electron-hole pair excitations involving both electrodes become possible, and contribute to the stimulated emission and absorption of phonons. We point out a generic mechanism for D-A molecules, where the stimulated emission can dominate beyond a certain voltage due to the inverted position of the D and A quantum resonances. This leads to current-driven amplification (negative damping) of the phonons similar to laser action. We investigate the effect in realistic molecular rectifier structures using first-principles calculations. PMID:21867028

  11. Capacitor-Filtered Half-Wave Rectifier

    NSDL National Science Digital Library

    This is an animation of a capacitor-filtered half-wave rectifier circuit or buck converter. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations. A link provides an optional Quicktime version of this same animation.Other 3-D Circuit Animations can be seen here.

  12. Iron loss of grain size controlled very thin grain-oriented silicon steels

    SciTech Connect

    Kim, Y.H.; Ohkawa, M.; Ishiyama, K.; Arai, K.I. (Tohoku Univ., Sendai (Japan). Research Institute of Electrical Communication)

    1993-11-01

    Very thin (less than 100 [mu]m) grain-oriented silicon steels are known to have lower iron loss than iron-based amorphous materials. It is possible to reduce the iron loss of very thin grain-oriented silicon steels further by applying new magnetic domain refining techniques. One method for magnetic domain refining is to control the grain size. The authors observed the magnetic domains and measured the iron loss of very thin grain-oriented silicon steels that had various grain sizes. They controlled grain size in samples to be from 0.25 mm to 2.3 mm without changing B[sub 8]. This experiment shows that the magnetic domain width can be made narrower by decreasing the grain size, which reduces the eddy current losses. On the other hand, samples with larger grain size have lower Hc and lower hysteresis losses. Therefore there is an optimum grain size for the lowest iron loss of very thin grain-oriented silicon steels.

  13. Controlling light with high-Q silicon photonic crystal nanocavities: Photon confinement, nonlinearity and coherence

    NASA Astrophysics Data System (ADS)

    Yang, Xiaodong

    The strong light localization and long photon lifetimes in two-dimensional silicon photonic crystal nanocavities with high quality factor (Q ) and subwavelength modal volume (V) significantly enhance the light-matter interactions, presenting many opportunities to explore new functionalities in silicon nanophotonic integrated circuits for on-chip all-optical information processing, optical computation and optical communications. This thesis will focus on the design, nanofabrication, and experimental characterization of both passive and active silicon nanophotonic devices based on two-dimensional high-Q silicon photonic crystal nanocavities. Three topics of controlling light with these high-Q nanocavities will be presented, including (1) photon confinement mechanism and cavity resonance tuning, (2) enhancement of optical nonlinearities, and (3) all-optical analogue to coherent interferences. The first topic is photon confinement in two-dimensional high- Q silicon photonic crystal nanocavities. In Chapter 2, the role of Q/V as the figure of merit for the enhanced light-matter interaction in optical microcavities and nanocavities is explained and different types of high-Q optical microcavities and nanocavities are reviewed with an emphasis on two-dimensional photonic crystal nanocavities. Then the nanofabrication process and the Q characterization are illustrated for the two-dimensional silicon photonic crystal nanocavities. In Chapter 3, the post-fabrication digital resonance tuning of high-Q silicon photonic crystal nanocavities using atomic layer deposition is proposed and demonstrated, with wide tuning range and precise control of cavity resonances while preserving high quality factors. The second topic is the enhancement of optical nonlinearities in two-dimensional high-Q silicon photonic crystal nanocavities, including stimulated Raman scattering and thermo-optical nonlinearities. In Chapter 4, the enhanced stimulated Raman scattering for low threshold Raman lasing in the designed high-Q silicon photonic crystal nanocavities are proposed and numerically analyzed through the derived coupled-mode equations, with various contributions on Raman gain, optical losses, and dispersion effects. In Chapter 5, the observation of enhanced optical nonlinearities and optical bistabilities due to the two-photon-absorption induced thermo-optic effect in high-Q silicon photonic crystal nanocavities with both Lorentzian resonances and Fano resonances is presented. The experimental results highlight the ultra-low switching energy, high switching contrast, and the low threshold wavelength detuning for Fano resonances, benefiting from the sharp and asymmetric Fano lineshapes. The third topic is all-optical analogue to coherent interference phenomena in atomic systems including Fano interference and electromagnetically induced transparency (EIT). In Chapter 5, the optical analogue to Fano interference is studied in an optical system consisting of a photonic crystal nanocavity side-coupled to a waveguide with two partially reflecting elements, where the coherent interference between the discrete energy state and the continuum will give sharp and asymmetric Fano lineshapes, which can be used for low-threshold optical bistable switching with a high switching contrast. In Chapter 6, another coherent interference phenomenon called electromagnetically induced transparency (EIT) is introduced. The deterministic tuning of all-optical analogue to EIT in coherently-coupled silicon photonic crystal nanocavities is demonstrated experimentally. Through thermo-optic tuning of wavelength detuning and phase difference between these coupled nanocavities, the stepwise control of the EIT-like coherent interference is realized. The designed EIT-like optical system is analyzed well through the coupled-mode equations. These results can be used for realization of all-optical stopping of light.

  14. Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  15. Development of silicone-based barrier devices for controlled delivery of spermicidal agents

    Microsoft Academic Search

    Chi-Hyun Lee; Robert E. Bagdon; Padmanabh P. Bhatt; Yie W. Chien

    1997-01-01

    Intravaginal devices (diaphragm and disc) were fabricated from silicone elastomer and evaluated for controlled release of Nonoxynol-9 (N-9). These intravaginal devices have good physical properties and reproducibility. A significant amount of N-9 was released within 2 min from vaginal devices; the release profile was found to follow Q vs. t1\\/2 relationship. The release flux increased with increasing loading dose of

  16. Controlled Nucleation Aerosol Reactors: Production of Bulk Silicon

    Microsoft Academic Search

    M. K. Alam; R. C. Flagan

    1986-01-01

    A new type of aerosol reactor is described. By controlling the rate of gas phase reactions such that vapor diffusion to existing particles is favored over homogeneous nucleation, a small number of seed particles can be grown to supermicron sizes. A model for the influence of growing particles on the rate of homogeneous nucleation has been used to design a

  17. Development of high temperature gallium phosphide rectifiers

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

    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.

  18. Alternating to Direct: Rectifying Alternating Current

    NSDL National Science Digital Library

    The Materials Science and Technology Teacher's Workshop (MAST) provides this activity for classes learning about diodes and electrical currents. The laboratory illustrates how diodes can be used to rectify alternating current. It uses a galvanometer to determine the direction of current flow when an AC or DC current is applied to the circuit containing a diode in series with a resistor and a galvanometer.The lesson includes step by step directions for the experiment.The activity should require about 20-30 minutes of class time to complete. Discussion questions and teacher notes are included.

  19. High precision quantum control of single donor spins in silicon

    E-print Network

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

    2007-05-15

    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.

  20. A comparative study of soft-switched CCM boost rectifiers and interleaved variable-frequency DCM boost rectifier

    Microsoft Academic Search

    Brian T. Irving; Yungtaek Jang; Milan M. Jovanovi?

    2000-01-01

    In this paper, three single-phase, high-power-factor rectifier implementations were evaluated on a comparative basis. Specifically, a zero-voltage-switching continuous-conduction-mode boost rectifier, a zero-current-zero-voltage-switching continuous-conduction-mode boost rectifier, and an interleaved variable-frequency discontinuous-conduction-mode boost rectifier were compared with respect to their efficiencies, compliance with the EN61000-3-2 specifications, complexity, and costs. The comparisons were done for the single-phase input voltage of 90 VRMS-264 VRMS

  1. Deposition of controllable preferred orientation silicon films on glass by inductively coupled plasma chemical vapor deposition

    SciTech Connect

    Li Junshuai [Department of Physics, Lanzhou University, 730000, Lanzhou, People's Republic of China and Faculty of Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan); Wang Jinxiao; Yin Min; Gao Pingqi; He Deyan [Department of Physics, Lanzhou University, 730000 Lanzhou (China); Chen Qiang; Li Yali; Shirai, Hajime [Faculty of Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570 (Japan)

    2008-02-15

    An inductively coupled plasma (ICP) system with the adjustable distance between the inductance coil and substrates was designed to effectively utilize the spatial confinement of ICP discharge, and then control the gas-phase transport process. The effects of the gas phase processes on the crystallinity and preferred orientation of silicon films deposited on glass were systematically investigated. The investigation was conducted in the ICP-chemical vapor deposition process with the precursor gas of a SiH{sub 4}/H{sub 2} mixture at a substrate temperature of 350 deg. Highly crystallized silicon films with different preferred orientations, (111) or (220), could be selectively deposited by adjusting the SiH{sub 4} dilution ratio [R=[SiH{sub 4}]/([SiH{sub 4}]+[H{sub 2}])] or total working pressure. When the total working pressure is 20 Pa, the crystallinity of the silicon films increases with the increase of the SiH{sub 4} dilution ratio, while the preferred orientation was changed from (111) to (220). In the case of the fixed SiH{sub 4} dilution (10%), the silicon film with I{sub (220)}/I{sub (111)} of about 3.5 and Raman crystalline fraction of about 89.6% has been deposited at 29.7 nm/min when the total working pressure was increased to 40 Pa. At the fixed SiH{sub 4} partial pressure of 2 Pa, the film crystallinity decreases and the preferred orientation is always (111) with increasing the H{sub 2} partial pressure from 18 to 58 Pa. Atomic force microscope reveals that the film deposited at a relatively high H{sub 2} partial pressure has a very rough surface caused by the devastating etching of H atoms to the silicon network.

  2. A full bridge soft switched telecom power supply with a current doubler rectifier

    Microsoft Academic Search

    Nasser H. Kutkut

    1997-01-01

    This paper presents a full bridge soft switched PWM telecom power supply with a current doubler rectifier. The full bridge PWM DC-to-DC power converter offers high power handling capability, minimum VA ratings for the main devices, no additional auxiliary components and simple PWM-based control strategy. Phase shift control is employed to regulate the output voltage and achieve soft switching. The

  3. Stability analysis of a series active filter integrated with a double-series diode rectifier

    Microsoft Academic Search

    Sunt Srianthumrong; Hideaki Fujita; Hirofumi Akagi

    2002-01-01

    This paper deals with a harmonic current-free AC\\/DC power conversion system which is characterized by the integration of a small-rated series active filter with a large-rated double-series diode rectifier. The stability of the active filter based on feedback control is discussed theoretically, taking into account delay time in the control circuit. As a result, it is revealed that the delay

  4. Inward rectifier current noise in frog skeletal muscle.

    PubMed Central

    DeCoursey, T E; Dempster, J; Hutter, O F

    1984-01-01

    Inwardly rectifying K+ currents were studied in cut muscle fibres from frogs using the Vaseline-gap voltage-clamp method. Both faces of the membrane were exposed to 120 mM-K+ methylsulphate solution. At small negative potentials, -10 and -21 mV, the current noise spectrum, after subtraction of a control spectrum at the zero current potential, could be fitted by a Lorentzian spectral component, usually with an additional 1/f component, where f is the frequency. At more negative potentials the 1/f component predominated. The zero frequency amplitude of the Lorentzian averaged 2.6 X 10(-24) A2 Hz-1 at -10 mV and 4.6 X 10(-24) A2 Hz-1 at -21 mV, with a mean half-power frequency, fc, of 34 Hz and 45 Hz, respectively. The time constant of the K+ current activation upon hyperpolarization agrees with that calculated from fc, and the Lorentzian disappears upon replacement of external K+ by tetraethylammonium (TEA+) or Rb+. Thus, the Lorentzian component appears to be ascribable to fluctuations originating in the inwardly rectifying mechanism. The noise spectra and macroscopic currents were interpreted by assuming that the inwardly rectifying K+ conductance is proportional to the product of two parameters: ps representing the state of the mechanism that gives rise to the observable macroscopic current relaxations and to the current fluctuations resulting in the observed Lorentzian spectra, and pf describing the instantaneous rectification of the single-channel conductance. Alternatively, pf may represent another mechanism in series with ps, but which fluctuates too rapidly to measure. Using this model the limiting single-channel conductance, gamma, was found to be approximately 9 pS. The corresponding specific density of channels is about 1 micron-2, assuming uniform distribution over all regions of the membrane. A preliminary value for gamma ( DeCoursey & Hutter , 1982) was derived without consideration of instantaneous rectification. Systematic errors in these results due to voltage decrement in the T-tubules are evaluated in an Appendix, and are found to be tolerably small in the voltage range studied. PMID:6330346

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

    PubMed

    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

    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

  6. Conditional Control of Donor Nuclear Spins in Silicon Using Stark Shifts

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  7. Molecular rectifiers and transistors based on ?-conjugated materials

    Microsoft Academic Search

    Siegmar Roth; Steffi Blumentritt; Marko Burghard; Erika Cammi; David Carroll; Seamus Curran; Georg Düsberg; Kun Liu; Jörg Muster; Günther Philipp; Thomas Rabenau

    1998-01-01

    Concepts and experimental results related to molecular rectifiers and transistors are reviewed. ‘Devices’ based on donor-? bridge-acceptor molecules, conjugated zwitterionic molecules, macrocyclic molecules, metal clusters, fullerenes and carbon nanotubes are discussed. Current-voltage characteristics showing rectifier properties are presented, as well as experiments in which the current-voltage characteristics are modulated by a gate voltage (transistor effect).

  8. The effects of DC ripple from cathodic protection rectifiers

    SciTech Connect

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

    1998-12-31

    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.

  9. Variants of rectifiers with near sinusoidal input currents

    Microsoft Academic Search

    M. Pletea; N. R. Buzatu; A. Serediuc; C. Nedelcu; I. V. Pletea

    2011-01-01

    Based on the characteristics of the rectifiers with near sinusoidal input currents (RNSIC-1, with capacitors connected on the DC side and RNSIC-2, with capacitors connected on the AC side), the paper proposes a comparative analysis between the performances of the two variants of RNSIC converters with three- phase six pulse full-bridge diode rectifiers with passive filters. A comparative analysis between

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

    PubMed

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

    2011-10-11

    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

  11. Candidate locations for SPS rectifying antennas

    NASA Technical Reports Server (NTRS)

    Eberhardt, A. W.

    1977-01-01

    The feasibility of placing 120 Satellite Power System (SPS) rectifying antenna (rectenna) sites across the U.S. was studied. An initial attempt is made to put two land sites in each state using several land site selection criteria. When only 69 land sites are located, it is decided to put the remaining sites in the sea and sea site selection criteria are identified. An estimated projection of electrical demand distribution for the year 2000 is then used to determine the distribution of these sites along the Pacific, Atlantic, and Gulf Coasts. A methodology for distributing rectenna sites across the country and for fine-tuning exact locations is developed, and recommendations on rectenna design and operations are made.

  12. Electrically conductive, black thermal control coatings for space craft application. II - Silicone matrix formulation

    NASA Technical Reports Server (NTRS)

    Hribar, V. F.; Bauer, J. L.; O'Donnell, T. P.

    1986-01-01

    Five black electrically conductive thermal-control coatings have been formulated and tested for application on the Galileo spacecraft. The coatings consisted of organic and inorganic systems applied on titanium and aluminum surfaces. The coatings were tested under simulated space environment conditions. Coated specimens were subjected to thermal radiation and convective and conductive heating from -196 to 538 C. Mechanical, physical, thermal, electrical, and optical characteristics, formulation, mixing, application, surface preparation of substrates, and a method of determining electrical resistance are presented for the silicone matrix formulation designated as GF-580.

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

    PubMed

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

    2014-10-01

    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

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

    PubMed Central

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

    2014-01-01

    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

  15. Influence of Lumped Snubber Capacitor on Input Current in Single-Phase Boost Rectifier

    NASA Astrophysics Data System (ADS)

    Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu; Yasukochi, Tomohiro

    The influence of a lumped snubber capacitor on an input current in the single-phase full-bridge boost rectifier is studied. The prototype, using two dual-switch power modules equipped with insulated-gate bipolar transistors and freewheeling diodes, operates in the continuous conduction mode under the current-mode control. The experimental results confirm that a relatively small lumped snubber capacitor contributes to the sinusoidal input current with a near-unity power factor.

  16. Compensation of power factor in rectifier systems utilized in oil drilling rigs

    Microsoft Academic Search

    P. P. A. Caldeira; E. H. Watanabe

    1988-01-01

    A detailed analysis of the power factor in three-phase rectifier systems utilized in oil drilling rigs is presented and the use of the thyristor controlled reactor\\/fixed capacitor as a solution to improve the power factor in these systems is proposed. The input\\/output mathematical models for the conventional full-bridge and modified converter for all firing angles and various types of load

  17. A high performance ZVT-PWM boost rectifier with soft switched auxiliary switch

    Microsoft Academic Search

    Yoon-Ho Kim; Yun-Bok Kim; Yong-Hyun Cho

    1998-01-01

    This paper presents a soft-switching average current control PWM high power factor boost converter. Conventional boost ZVT-PWM converter has a disadvantage of hard-switching for auxiliary switch at turn-off. A soft switched auxiliary switch is proposed to achieve a high performance ZVT-PWM boost rectifier. The simulation and experimental results show that soft switching operation can be maintained for wide line and

  18. Outdoor performance stability and controlled light-soak testing of amorphous silicon multijunction modules at NREL

    SciTech Connect

    Mrig, L.; Burdick, J.; Luft, W.; Kroposki, B. [National Renewable Energy Lab., Golden, CO (United States)

    1994-12-31

    The National Renewable Energy Laboratory (NREL) has been testing amorphous silicon (a-Si) Photovoltaic (PV) modules for more than a decade. NREL has been conducting controlled light-soak testing of multijunction a-Si modules to characterize their performance for stability evaluation as well as to benchmark the technology status. Some of the test modules, after controlled light-soak testing, have been installed outdoors. The authors have observed that under outdoor exposure, the modules further degrade in performance, possibly due to lower outdoor temperatures and varying spectra. The paper presents data on the light-induced degradation for the third controlled light-soak test on multijunction a-Si modules as well as outdoor performance data on single- and multijunction modules under prevailing conditions.

  19. The black silicon method: a universal method for determining the parameter setting of a fluorine-based reactive ion etcher in deep silicon trench etching with profile control

    Microsoft Academic Search

    Henri Jansen; Boer de Meint; Rob Legtenberg; Miko Elwenspoek

    1995-01-01

    Very deep trenches (up to 200 pm) with high aspect ratios (up to 10) in silicon and polymers are etched using a fluorine-based plasma (SFd02\\/CHF3). Isotropic, positively and negatively (i.e. reverse) tapered as well as.fully vertical walls with smooth suriaces are achieved by controlling the plasma chemistry. A convenient way to find the processing conditions needed for a vertical wall

  20. Simultaneous phosphorus and Si self-diffusion in extrinsic, isotopically controlled silicon heterostructures

    SciTech Connect

    Silvestri, Hughes H.; Bracht, Hartmut A.; Sharp, Ian D.; Hansen, John; Nylandsted-Larsen, Arne; Haller, Eugene E.

    2003-04-22

    We present experimental results of impurity and self-diffusion in an isotopically controlled silicon heterostructure extrinsically doped with phosphorus. As a consequence of extrinsic doping, the concentration of singly negatively charged native defects is enhanced and the role of these native defect charge states in the simultaneous phosphorus and Si self-diffusion can be determined. Multilayers of isotopically controlled {sup 28}Si and natural silicon enable simultaneous analysis of {sup 30}Si self-diffusion into the {sup 28}Si enriched layers and phosphorus diffusion throughout the multilayer structure. An amorphous 260 nm thick Si cap layer was deposited on top of the Si isotope heterostructure. The phosphorus ions were implanted to a depth such that all the radiation damage resided inside this amorphous cap layer, preventing the generation of excess native defects and enabling the determination of the Si self-diffusion coefficient and the phosphorus diffusivity under equilibrium conditions. These samples were annealed at temperatures between 950 and 1100 C to study the diffusion. Detailed analysis of the diffusion process was performed on the basis of a P diffusion model which involves neutral and positively charged mobile P species and neutral and singly negatively charged self-interstitial.

  1. Silicon-based current-controlled reconfigurable magnetoresistance logic combined with non-volatile memory

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaozhong; Luo, Zhaochu

    2015-03-01

    Silicon-based complementary metal-oxide-semiconductor (CMOS) transistors have achieved great success. However, the traditional development pathway is approaching its fundamental limits. Magnetoelectronics logic, especially magnetic-field-based logic, shows promise for surpassing the development limits of CMOS logic. Existing proposals of magnetic-field-based logic are based on exotic semiconductors and difficult for further technological implementation. We proposed a kind of diode-assisted geometry-enhanced low-magnetic-field magnetoresistance (MR) mechanism. It couples p-n junction's nonlinear transport characteristic and Lorentz force by geometry, and shows extremely large low-magnetic-field MR (>120% at 0.15 T) Further, it is applied to experimentally demonstrate current-controlled reconfigurable MR logic on the silicon platform at room temperature. This logic device could perform Boolean logic AND, OR, NAND and NOR in one device. Combined with non-volatile magnetic memory, this logic architecture has the advantages of current-controlled reconfiguration, zero refresh consumption, instant-on performance and would bridge the processor-memory gap.

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

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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 current–voltage 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.

  4. Strain and Electric Field Control of Hyperfine Interactions for Donor Spin Qubits in Silicon

    E-print Network

    Usman, Muhammad; Rahman, Rajib; Klimeck, Gerhard; Simmons, Michelle Y; Rogge, Sven; Hollenberg, Lloyd C L

    2015-01-01

    Control of hyperfine interactions is a fundamental requirement for quantum computing architecture schemes based on shallow donors in silicon. However, at present, there is lacking an atomistic approach including critical effects of central-cell corrections and non-static screening of the donor potential capable of describing the hyperfine interaction in the presence of both strain and electric fields in realistically sized devices. We establish and apply a theoretical framework, based on atomistic tight-binding theory, to quantitatively determine the strain and electric field dependent hyperfine couplings of donors. Our method is scalable to millions of atoms, and yet captures the strain effects with an accuracy level of DFT method. Excellent agreement with the available experimental data sets allow reliable investigation of the design space of multi-qubit architectures, based on both strain-only as well as hybrid (strain+field) control of qubits. The benefits of strain are uncovered by demonstrating that a h...

  5. Fabrication of Size-Controlled Gold Nanoparticles on Silicone Oil Surface and Mechanism for Size-Controllability

    NASA Astrophysics Data System (ADS)

    Zhang, Chuhang; Feng, Yuanxin

    2015-07-01

    By thermal evaporation method, size-controlled gold (Au) nanoparticles were fabricated on silicone oil surface and the growth mechanism was investigated. Atomic force microscopy (AFM) study showed that quasi-circular granules with height of 10.0 nm and diameter of 60.0 nm were formed on the oil surface, which was independent with substrate temperature Ts. Transmission electron microscopy (TEM) observation revealed that the granules were further composed of Au nanoparticles. By changing Ts from 285 to 343 K, the mean diameter of nanoparticles can be well manipulated from 7.2 ± 0.7 to 10.1 ± 1.0 nm. The one dimensional power spectra density analysis and high resolution TEM study demonstrated that the origin of the size-controllability of the Au nanoparticles were dominated by the simple aggregation of small nanoparticles. Subsequently, a sequential growth model for Au nanoparticle was presented.

  6. The Effect of Rectifier Discontinuous Current on Motor Performance

    Microsoft Academic Search

    K. G. Black

    1964-01-01

    Rectifier performance with the low-inductance counter electromotive force (emf) load of a large d-c motor may be some-what different than the more conventional performance resulting from a highly inductive load. If, at low average values, the current is not continuous but flows in pulses, both the static and the dynamic characteristics of the rectifier-motor system are affected. In the case

  7. Programmable PFC based hybrid multipulse power rectifier for ultra clean power application

    Microsoft Academic Search

    Luiz Carlos Gomes de Freitas; Marcelo G. Simões; Carlos Alberto Canesin

    2006-01-01

    A novel hybrid three-phase rectifier is proposed. It is capable to achieve high input power factor (PF) and low total harmonic input currents distortion (THDI). The proposed hybrid high power rectifier is composed by a standard three-phase six-pulse diode rectifier (Graetz bridge) with a parallel connection of single-phase Sepic rectifiers in each three-phase rectifier leg. Such topology results in a

  8. Programmable PFC Based Hybrid Multipulse Power Rectifier for Utility Interface of Power Electronic Converters

    Microsoft Academic Search

    L. C. Gomes de Freitas; E. A. A. Coelho; A. P. Finazzi; M. G. Simoes; C. A. Canesin

    2005-01-01

    In this paper it is proposed a novel hybrid three-phase rectifier capable to achieve high input power factor (PF), and low total harmonic distortion in the input currents (THDI). The proposed hybrid high power rectifier is composed by a standard three-phase 6-pulses diode rectifier (Graetz bridge) with a parallel connection of single-phase boost rectifiers in each three-phase rectifier leg. Such

  9. Silicon spintronics

    NASA Astrophysics Data System (ADS)

    Jansen, Ron

    2012-05-01

    Worldwide efforts are underway to integrate semiconductors and magnetic materials, aiming to create a revolutionary and energy-efficient information technology in which digital data are encoded in the spin of electrons. Implementing spin functionality in silicon, the mainstream semiconductor, is vital to establish a spin-based electronics with potential to change information technology beyond imagination. Can silicon spintronics live up to the expectation? Remarkable advances in the creation and control of spin polarization in silicon suggest so. Here, I review the key developments and achievements, and describe the building blocks of silicon spintronics. Unexpected and puzzling results are discussed, and open issues and challenges identified. More surprises lie ahead as silicon spintronics comes of age.

  10. Modeling and control of a silicon substrate heater for carbon nanotube growth experiments

    E-print Network

    Held, David (David A.)

    2005-01-01

    The precision engineering research group at MIT is working on carbon nanotube growth experiments on silicon substrates and in microfabricated silicon devices, to try to produce improved bulk nanotube growth. For this thesis, ...

  11. Controlling the surface roughness of epitaxial SiC on silicon

    NASA Astrophysics Data System (ADS)

    Mishra, N.; Hold, L.; Iacopi, A.; Gupta, B.; Motta, N.; Iacopi, F.

    2014-05-01

    The surface of cubic silicon carbide (3C-SiC) hetero-epitaxial films grown on the (111) surface of silicon is a promising template for the subsequent epitaxial growth of III-V semiconductor layers and graphene. We investigate growth and post-growth approaches for controlling the surface roughness of epitaxial SiC to produce an optimal template. We first explore 3C-SiC growth on various degrees of offcut Si(111) substrates, although we observe that the SiC roughness tends to worsen as the degree of offcut increases. Hence we focus on post-growth approaches available on full wafers, comparing chemical mechanical polishing (CMP) and a novel plasma smoothening process. The CMP leads to a dramatic improvement, bringing the SiC surface roughness down to sub-nanometer level, though removing about 200 nm of the SiC layer. On the other hand, our proposed HCl plasma process appears very effective in smoothening selectively the sharpest surface topography, leading up to 30% improvement in SiC roughness with only about 50 nm thickness loss. We propose a simple physical model explaining the action of the plasma smoothening.

  12. Isolation and Control of Spins in Silicon Carbide with Millisecond-Coherence Times

    NASA Astrophysics Data System (ADS)

    Christle, David J.; Falk, Abram L.; Andrich, Paolo; Klimov, Paul V.; Awschalom, David D.; Hassan, Jawad Ul; Son, Nguyen T.; Janzén, Erik; Ohshima, Takeshi

    2015-03-01

    The elimination of defects from silicon carbide (SiC) has facilitated its move to the forefront of the optoelectronics and power-electronics industries. Nonetheless, because the electronic states of SiC defects can have sharp optical and spin transitions, they are increasingly recognized as a valuable resource for quantum-information and nanoscale-sensing applications. We demonstrate that individual electronic spin states of the divacancy defect in highly purified monocrystalline 4H-SiC can be isolated and coherently controlled. This defect has analogous behavior to the prominent nitrogen-vacancy center in diamond, yet exists in a material amenable to modern growth and microfabrication techniques. We spectroscopically identify the different forms of divacancies, and show that divacancy spins exhibit an exceptionally long ensemble Hahn-echo coherence time that exceeds one millisecond. Funding by NSF, AFOSR MURI, and the Knut & Alice Wallenberg Foundation is gratefully acknowledged.

  13. Controlled growth of monolayer graphene on silicon carbide in argon atmosphere

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

    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.

  14. Electrical control of interfacial trapping for magnetic tunnel transistor on silicon

    SciTech Connect

    Lu, Y., E-mail: yuan.lu@univ-lorraine.fr; Lacour, D.; Lengaigne, G.; Le Gall, S.; Suire, S.; Montaigne, F.; Hehn, M. [Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, Boulevard des Aiguillettes, BP 239, 54506 Vandoeuvre (France); Wu, M. W. [Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, University of Science and Technology of China, Hefei, Anhui, 230026 (China)

    2014-01-27

    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)

  15. Brownian Motion Rectifier: Continuous Sorting of Macromolecules in a Microfabricated Sieve

    NASA Astrophysics Data System (ADS)

    Chou, C. F.; Duke, T. A. J.; Chan, S. S.; Bakajin, O. B.; Austin, R. H.; Cox, E. C.

    1998-03-01

    A new method for separating biological macromolecules according to size has been proposed by Duke and Austin (T.A.J. Duke and R.H. Austin, preprint (1997).). A fine stream of molecules is transported through a microfabricated sieve, etched from a silicon chip by photolithography. The sieve consists of a periodic array of oblong obstacles, oriented at an angle to the direction of flow. The spatial asymmetry and the broken time-reversal symmetry (imposed by the flow) cause the Brownian motion of the molecules to be rectified. Since the effect depends on the thermal motion, molecules with different diffusion coefficients are deflected by different amounts, and consequently a mixture of molecules is sorted according to size. Our preliminary results in sorting a mixture of DNA in such a sieve will be presented.

  16. Role of silicone derivative plus onion extract gel in presternal hypertrophic scar protection: a prospective randomized, double blinded, controlled trial.

    PubMed

    Jenwitheesuk, Kamonwan; Surakunprapha, Palakorn; Jenwitheesuk, Kriangsak; Kuptarnond, Chusak; Prathanee, Sompop; Intanoo, Worawit

    2012-08-01

    Use of silicone derivative and onion extract had been reported in the prevention of hypertrophic scarring. Our experience showed the preventive use of silicone derivative plus onion extract gel on hypertrophic scars after median sternotomy. In a randomized, double blinded, placebo-controlled study, 60 patients after median sternotomy incisions were separated into two groups. All patients were treated either with silicone derivative plus onion extract gel (Cybele(®) scagel) or placebo gel twice daily for a total treatment period of 12 weeks. During each visit, pain and itching scores were graded by the patients and scar characteristics were observed by surgeons using the Vancouver scar scale. Pain and itch score values from patients' who applied silicone derivative plus onion extract gel was less than another group (P < 0·05). Pigmentation was significantly different between two groups (P < 0·05) and the reduction of scores on vascularity, pliability, height in treated group was not superior to the untreated group. No adverse events were reported by any of the patients. A silicone derivative plus onion extract gel is safe and effective for the preventing the hypertrophic scarring after median sternotomy. PMID:22168750

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  18. Observation of DNA dynamics near silicon nanopores by controlling the ultraviolet light spot

    NASA Astrophysics Data System (ADS)

    Yamazaki, Hirohito; Ito, Shintaro; Esashika, Keiko; Saiki, Toshiharu

    2015-03-01

    Biopolymer translocation through a nanopore is an attractive phenomenon in the field of biophysics. When the voltage is applied through a nanopore, DNA coils thread into a nanopore by deforming its coil structure and recoil after translocation through a nanopore. Because DNA coil structure is relative with DNA translocation, DNA dynamics near a nanopore have a correlation with DNA translocation. To investigate DNA dynamics, we developed the optical nanopore detection system, which has a capability to observe DNA dynamics near nanopore at sub-100-nm and sub-millisecond resolutions. Here, we report our experimental results of DNA dynamics near nanopores by controlling position of light spots. Because silicon have high refractive index and extinction coefficient at ultraviolet light, the ultraviolet light creates z- and x-polarized light spot, which locate on nanopores and 50 nm apart from nanopores, respectively. By controlling light polarization, we observed different fluorescence intensity traces between z- and x-polarized light spot. The experimental results showed that fluorescence intensity trance of z-polarized light spot decayed faster than that of x-polarized light spot, which explain DNA dynamics near nanopores change by position from nanopores.

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

    SciTech Connect

    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

    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.

  20. Strain and Electric Field Control of Hyperfine Interactions for Donor Spin Qubits in Silicon

    E-print Network

    Muhammad Usman; Charles D. Hill; Rajib Rahman; Gerhard Klimeck; Michelle Y. Simmons; Sven Rogge; Lloyd C. L. Hollenberg

    2015-04-24

    Control of hyperfine interactions is a fundamental requirement for quantum computing architecture schemes based on shallow donors in silicon. However, at present, there is lacking an atomistic approach including critical effects of central-cell corrections and non-static screening of the donor potential capable of describing the hyperfine interaction in the presence of both strain and electric fields in realistically sized devices. We establish and apply a theoretical framework, based on atomistic tight-binding theory, to quantitatively determine the strain and electric field dependent hyperfine couplings of donors. Our method is scalable to millions of atoms, and yet captures the strain effects with an accuracy level of DFT method. Excellent agreement with the available experimental data sets allow reliable investigation of the design space of multi-qubit architectures, based on both strain-only as well as hybrid (strain+field) control of qubits. The benefits of strain are uncovered by demonstrating that a hybrid control of qubits based on (001) compressive strain and in-plane (100 or 010) fields results in higher gate fidelities and/or faster gate operations, for all of the four donor species considered (P, As, Sb, and Bi). The comparison between different donor species in strained environments further highlights the trends of hyperfine shifts, providing predictions where no experimental data exists. Whilst faster gate operations are realisable with in-plane fields for P, As, and Sb donors, only for the Bi donor, our calculations predict faster gate response in the presence of both in-plane and out-of-plane fields, truly benefiting from the proposed planar field control mechanism of the hyperfine interactions.

  1. Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

    NASA Astrophysics Data System (ADS)

    Usman, M.; Hill, C. D.; Rahman, R.; Klimeck, G.; Simmons, M. Y.; Rogge, S.; Hollenberg, L. C. L.

    2015-06-01

    Control of hyperfine interactions is a fundamental requirement for quantum computing architecture schemes based on shallow donors in silicon. However, at present, there is lacking an atomistic approach including critical effects of central-cell corrections and nonstatic screening of the donor potential capable of describing the hyperfine interaction in the presence of both strain and electric fields in realistically sized devices. We establish and apply a theoretical framework, based on atomistic tight-binding theory, to quantitatively determine the strain and electric-field-dependent hyperfine couplings of donors. Our method is scalable to millions of atoms, and yet captures the strain effects with an accuracy level of DFT method. Excellent agreement with the available experimental data sets allow reliable investigation of the design space of multiqubit architectures, based on both strain only as well as hybrid (strain + field) control of qubits. The benefits of strain are uncovered by demonstrating that a hybrid control of qubits based on (001) compressive strain and in-plane (100 or 010) fields results in higher gate fidelities and or faster gate operations, for all of the four donor species considered (P, As, Sb, and Bi). The comparison between different donor species in strained environments further highlights the trends of hyperfine shifts, providing predictions where no experimental data exists. While faster gate operations are realizable with in-plane fields for P, As, and Sb donors, only for the Bi donor, our calculations predict faster gate response in the presence of both in-plane and out-of-plane fields, truly benefiting from the proposed planar field control mechanism of the hyperfine interactions.

  2. Design and Evaluation of a 42-V Automotive Alternator With Integrated Switched-Mode Rectifier

    E-print Network

    Tang, Sai Chun

    This paper presents techniques for the design of high-power Lundell alternators with integrated switched-mode rectifiers. A multisection stator winding and interleaved rectifier arrangement is introduced that enables high ...

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

    NASA Astrophysics Data System (ADS)

    Bhat, Abdul Hamid; Langer, Nitin

    2014-12-01

    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.

  4. Junction barrier Schottky rectifier with an improved P-well region

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Li, Ting; Cao, Fei; Shao, Lei; Chen, Yu-Xian

    2012-12-01

    A junction barrier Schottky (JBS) rectifier with an improved P-well on 4H—SiC is proposed to improve the VF—IR trade-off and the breakdown voltage. The reverse current density of the proposed JBS rectifier at 300 K and 800 V is about 3.3×10-8 times that of the common JBS rectifier at no expense of the forward voltage drop. This is because the depletion layer thickness in the P-well region at the same reverse voltage is larger than in the P+ grid, resulting in a lower spreading current and tunneling current. As a result, the breakdown voltage of the proposed JBS rectifier is over 1.6 kV, that is about 0.8 times more than that of the common JBS rectifier due to the uniform electric field. Although the series resistance of the proposed JBS rectifier is a little larger than that of the common JBS rectifier, the figure of merit (FOM) of the proposed JBS rectifier is about 2.9 times that of the common JBS rectifier. Based on simulating the values of susceptibility of the two JBS rectifiers to electrostatic discharge (ESD) in the human body model (HBM) circuits, the failure energy of the proposed JBS rectifier increases 17% compared with that of the common JBS rectifier.

  5. A RF to DC Voltage Conversion Model for MultiStage Rectifiers in UHF RFID Transponders

    Microsoft Academic Search

    Raymond E. Barnett; Jin Liu; Steve Lazar

    2009-01-01

    This paper presents a RF to DC conversion model for multi-stage rectifiers in UHF RFID transponders. An equation relating the RF power available from the antenna to the DC output voltage produced by a multi-stage rectifier is presented. The proposed model includes effects of the nonlinear forward voltage drop in diodes and impedance matching conditions of the antenna to rectifier

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

    E-print Network

    Ballistic Rectifiers Z. Bennett, M. Koyama, T. Hayafuji, S. Sasa, T. Maemoto, M. Inoue Nanomaterials Microdevices Research Center Osaka Institute of Technology, Osaka, Japan What is a ballistic to direct current usually using a P-N junction. A ballistic rectifier is a rectifier that relies

  7. Geometry enhanced asymmetric rectifying tunneling diodes Kwangsik Choi,a

    E-print Network

    Dagenais, Mario

    Geometry enhanced asymmetric rectifying tunneling diodes Kwangsik Choi,a Geunmin Ryu, Filiz in the layout of tunnel diodes yields asymmetry in the current-voltage I-V relationships associated/Au and for Ni­NiO­Ni tunneling structures. For a polysilicon­SiO2­Ti/Au asymmetric tunneling diode ATD

  8. Oscillator & Rectifier Analysis for use in large flex electronics

    E-print Network

    Petta, Jason

    : Liechao Huang #12;LARGE AREA FLEX ELECTRONICS Integrated circuits that are built on or into flexibleOscillator & Rectifier Analysis for use in large flex electronics PCCM/Prism Summer 2011 REU. #12;Oscillator · Simply put, a circuit or device that converts DC into AC is called an oscillator

  9. Seismic triggering by rectified diffusion in geothermal systems

    Microsoft Academic Search

    Bradford Sturtevant; Hiroo Kanamori; Emily E. Brodsky

    1996-01-01

    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

  10. Characteristics and Applications of Selenium-Rectifier Cells

    Microsoft Academic Search

    E. A. Harty

    1943-01-01

    The rectification properties of selenium cells were first discovered in the year 1883. C. T. Fritts described them in the American Journal of Science.11,12 However, they were never used to any extent, except possibly as photocells. After the introduction of the copperoxide rectifier, research activities were stimulated, and selenium cells were again rediscovered. The first commercial cells were made in

  11. Voltage sag detection based on rectified voltage processing

    Microsoft Academic Search

    Andrea Florio; Andrea Mariscotti; Maurizio Mazzucchelli

    2004-01-01

    An algorithm for voltage sag detection based on rectified voltage processing is presented and its performances are evaluated by means of simulated and real voltage waveforms (recorded at some low-voltage busbars and measured on a scaled prototype of a voltage support system). The algorithm is intended to detect voltage sag occurrence and to trigger the disconnection of the faulty supply

  12. 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

  13. Inward rectifiers and their regulation by endogenous polyamines

    PubMed Central

    Baronas, Victoria A.; Kurata, Harley T.

    2014-01-01

    Inwardly-rectifying potassium (Kir) channels contribute to maintenance of the resting membrane potential and regulation of electrical excitation in many cell types. Strongly rectifying Kir channels exhibit a very steep voltage dependence resulting in silencing of their activity at depolarized membrane voltages. The mechanism underlying this steep voltage dependence is blockade by endogenous polyamines. These small multifunctional, polyvalent metabolites enter the long Kir channel pore from the intracellular side, displacing multiple occupant ions as they migrate to a stable binding site in the transmembrane region of the channel. Numerous structure-function studies have revealed structural elements of Kir channels that determine their susceptibility to polyamine block, and enable the steep voltage dependence of this process. In addition, various channelopathies have been described that result from alteration of the polyamine sensitivity or activity of strongly rectifying channels. The primary focus of this article is to summarize current knowledge of the molecular mechanisms of polyamine block, and provide some perspective on lingering uncertainties related to this physiologically important mechanism of ion channel blockade. We also briefly review some of the important and well understood physiological roles of polyamine sensitive, strongly rectifying Kir channels, primarily of the Kir2 family. PMID:25221519

  14. Optics to rectify CORONA panoramic photographs for map making

    NASA Astrophysics Data System (ADS)

    Hilbert, Robert S.

    2006-08-01

    In the 1960's, accurate maps of the United States were available to all, from the U.S. Government, but maps of the Soviet Union were not, and in fact were classified. Maps of the Soviet Union were needed by the U.S. Government, including for U.S. targeting of Soviet ICBM sites, and for negotiating the SALT ICBM disarmament treaty. Although mapping cameras were historically frame cameras with low distortion, the CORONA panoramic film coverage was used to identify any ICBM sites. If distortion-free photographs could be produced from this inherently distorted panoramic material, accurate maps could be produced that would be valuable. Use of the stereo photographs from CORONA, for developing accurate topographical maps, was the mission of Itek's Gamma Rectifier. Bob Shannon's department at Itek was responsible for designing the optics for the Gamma Rectifier. He assigned the design to the author. The optical requirements of this system are described along with the optical design solution, which allowed the inherent panoramic distortion of the original photographs to be "rectified" to a very high level of accuracy, in enlarged photographs. These rectifiers were used three shifts a day, for over a decade, and produced the most accurate maps of the earth's surface, that existed at that time. The results facilitated the success of the Strategic Arms Limitation Talks (SALT) Treaty signed by the US and the Soviet Union in 1972, which were verified by "national means of verification" (i.e. space reconnaissance).

  15. Stress control of plasma enhanced chemical vapor deposited silicon oxide film from tetraethoxysilane

    NASA Astrophysics Data System (ADS)

    Guan, D.; Bruccoleri, A. R.; Heilmann, R. K.; Schattenburg, M. L.

    2014-02-01

    Thin silicon dioxide films have been studied as a function of deposition parameters and annealing temperatures. Films were deposited by tetraethoxysilane (TEOS) dual-frequency plasma enhanced chemical vapor deposition with different time interval fractions of high-frequency and low-frequency plasma depositions. The samples were subsequently annealed up to 930 °C to investigate their stress behavior. Films that were deposited in high-frequency dominated plasma were found to have tensile residual stress after annealing at temperatures higher than 800 °C. The residual stress can be controlled to slightly tensile by changing the annealing temperature. High tensile stress was observed during the annealing of high-frequency plasma-deposited films, leading to film cracks that limit the film thickness, as predicted by the strain energy release rate equation. Thick films without cracks were obtained by iterating deposition and annealing to stack multiple layers. A series of wet cleaning experiments were conducted, and we discovered that water absorption in high-frequency plasma-deposited films causes the residual stress to decrease. A ?40 nm thick low-frequency deposited oxide cap is sufficient to prevent water from diffusing through the film. Large-area free-standing tensile stressed oxide membranes without risk of buckling were successfully fabricated.

  16. Interface control and mechanical property improvements in silicon carbide/titanium composites

    NASA Technical Reports Server (NTRS)

    Brewer, W. D.; Unnam, J.

    1982-01-01

    Several composite systems made of titanium matrix reinforced with silicon carbide fiber were investigated to obtain a better understanding of composite-degradation mechanisms and to develop techniques to minimize loss of mechanical properties during fabrication and in service. Emphasis was on interface control by fiber or matrix coatings. X-ray diffraction studies on planar samples showed that the formation of titanium silicides was greatly inhibited by the presence of aluminum or Ti3A1 layers at the fiber-matrix interface, with the Ti3A1 being more effective in reducing the reactions. Fiber studies showed that coating the fiber with a 1-micron-thick layer of aluminum improved the as-fabricated strength of a stoichiometric SiC fiber and reduced the fiber degradation during exposure to composite-fabrication conditions. Applying an interfacial barrier by coating the matrix foils instead of the fibers was found to be an effective method for improving composite strength. Reducing the fabrication temperature also resulted in significant improvements in composite strengths. Good-quality, well-consolidated composites were fabricated at temperatures well below those currently used for SiC-Ti composite fabrication.

  17. Controllable chemical vapor deposition of large area uniform nanocrystalline graphene directly on silicon dioxide

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Lindvall, Niclas; Cole, Matthew T.; Wang, Teng; Booth, Tim J.; Bøggild, Peter; Teo, Kenneth B. K.; Liu, Johan; Yurgens, August

    2012-02-01

    Metal-catalyst-free chemical vapor deposition (CVD) of large area uniform nanocrystalline graphene on oxidized silicon substrates is demonstrated. The material grows slowly, allowing for thickness control down to monolayer graphene. The as-grown thin films are continuous with no observable pinholes, and are smooth and uniform across whole wafers, as inspected by optical-, scanning electron-, and atomic force microscopy. The sp2 hybridized carbon structure is confirmed by Raman spectroscopy. Room temperature electrical measurements show ohmic behavior (sheet resistance similar to exfoliated graphene) and up to 13% of electric-field effect. The Hall mobility is ˜40 cm2/Vs, which is an order of magnitude higher than previously reported values for nanocrystalline graphene. Transmission electron microscopy, Raman spectroscopy, and transport measurements indicate a graphene crystalline domain size ˜10 nm. The absence of transfer to another substrate allows avoidance of wrinkles, holes, and etching residues which are usually detrimental to device performance. This work provides a broader perspective of graphene CVD and shows a viable route toward applications involving transparent electrodes.

  18. Functional Nanoscale Electronic Devices Assembled Using Silicon Nanowire Building Blocks

    Microsoft Academic Search

    Yi Cui; Charles M. Lieber

    2001-01-01

    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

  19. Selective etching of silicon in aqueous ammonia solution

    Microsoft Academic Search

    Lai-Cheng Chen; Minjan Chen; Tay-Her Tsaur; Chenhsin Lien; Chi-Chao Wan

    1995-01-01

    The current-voltage (I-V) characteristics of silicon in aqueous ammonia have been studied. As the bias is swept to the cathodic direction and kept cathodic for a few minutes, clear passivation peaks in the I-V curves can be observed for both p- and n-type silicon. A linear current-voltage relation is observed for the n-Si\\/NH4OH contact. A rectifying current-voltage relation with large

  20. Analysis and design for reducing voltage stress in output rectifier of LFLRV SIV DC-DC converter

    Microsoft Academic Search

    Diao Lijun; Chen Jie; Lin Wenli; Liu Zhigang

    2009-01-01

    This paper presents a full-bridge full-wave DC-DC converter used in 35 kVA power grade auxiliary static inverter (SIV) of first low-floor light rail vehicle (LFLRV) in China, where reducing voltage stress in output rectifier diodes is so important for the converter reliability. DC-bias function of high frequency transformer is analyzed and a sensorless digital dc-bias control method by DSP and

  1. Silicon carbide process development for microengine applications : residual stress control and microfabrication

    E-print Network

    Choi, Dongwon, 1973-

    2004-01-01

    The high power densities expected for the MIT microengine (silicon MEMS-based micro-gas turbine generator) require the turbine and compressor spool to rotate at a very high speed at elevated temperatures (1300 to 1700 K). ...

  2. A directional current switch using silicon single electron transistors controlled by charge injection into silicon nano-crystal floating dots

    Microsoft Academic Search

    N. Takahashi; H. Ishikuro; T. Hiramoto

    1999-01-01

    A directional current switch is fabricated using two single electron transistors (SETs) with a common gate electrode. In order to adjust the peak positions of Coulomb blockade oscillations, SETs with Si nanocrystal floating dots are utilized. The phases of two SETs are separately controlled using only one gate electrode and the operation of current switch is successfully demonstrated. This method

  3. Crystal structure of the eukaryotic strong inward-rectifier K+ channel Kir2.2 at 3.1 A resolution.

    PubMed

    Tao, Xiao; Avalos, Jose L; Chen, Jiayun; MacKinnon, Roderick

    2009-12-18

    Inward-rectifier potassium (K+) channels conduct K+ ions most efficiently in one direction, into the cell. Kir2 channels control the resting membrane voltage in many electrically excitable cells, and heritable mutations cause periodic paralysis and cardiac arrhythmia. We present the crystal structure of Kir2.2 from chicken, which, excluding the unstructured amino and carboxyl termini, is 90% identical to human Kir2.2. Crystals containing rubidium (Rb+), strontium (Sr2+), and europium (Eu3+) reveal binding sites along the ion conduction pathway that are both conductive and inhibitory. The sites correlate with extensive electrophysiological data and provide a structural basis for understanding rectification. The channel's extracellular surface, with large structured turrets and an unusual selectivity filter entryway, might explain the relative insensitivity of eukaryotic inward rectifiers to toxins. These same surface features also suggest a possible approach to the development of inhibitory agents specific to each member of the inward-rectifier K+ channel family. PMID:20019282

  4. An Integrated Amorphous Silicon Gate Driver Circuit Using Voltage-Controlled Capacitance Modeling for High Definition Television

    NASA Astrophysics Data System (ADS)

    Han, Sang-Kug; Choi, Hoon; Moon, Kyo-Ho; Choi, Young-Seok; Jeong, Kyung-Deuk; Park, Kwang-Mook; Choi, Sie-Young

    2012-04-01

    We have developed the integrated amorphous silicon gate driver circuit using the model extraction technique of the inverted staggered and nonsymmetric amorphous silicon (a-Si) thin film transistor. The relation between capacitance characteristics of hydrogenated a-Si (a-Si:H) integrated transistors and the output signal of the gate driver circuit is analyzed using UTMOST IV ver. 1.6.4.R and SMARTSPICE ver. 3.19.15.C. The accuracy of the simulated gate output signal using voltage-controlled capacitance modeling is verified with measured data. The a-Si gate driver circuit using the proposed (TFT) model increased the accuracy of rising (95.3%) and falling (92%) time, compared to the conventional model. The suggested model extraction technique can be used for bottom gate and asymmetric TFT structures.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  6. 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.

  7. Integrated high quality rectifier-regulators

    Microsoft Academic Search

    Michael Madigan; Robert Erickson; Esam Ismail

    1992-01-01

    A family of AC-to-DC converters which integrate the functions of low harmonic rectification, low frequency energy storage, and wide bandwidth output voltage control into a single converter containing one, two, or four active switches is presented. These converters utilize a discontinuous conduction mode input inductor, an internal energy storage capacitor, and transformer secondary circuits which resemble the bridge, forward, flyback,

  8. Properties of the K + inward rectifier in the plasma membrane of xylem parenchyma cells from barley roots: Effects of TEA + , Ca 2+ , Ba 2+ and La 3+

    Microsoft Academic Search

    L. H. Wegner; A. H. De Boer; K. Raschke

    1994-01-01

    Xylem parenchyma cells are situated around the (apoplastic) xylem vessels and are involved in the control of the composition of the xylem sap by exporting and resorbing solutes. We investigated properties of the K+ inward rectifier in the plasma membrane of these cells by performing patch clamp experiments on protoplasts in the whole-cell configuration. Inward currents were sensitive to the

  9. Interaction Mechanisms between Polyamines and IRK1 Inward Rectifier KChannels

    Microsoft Academic Search

    Donglin Guo; Zhe Lu

    Rectification of macroscopic current through inward-rectifier K ? (Kir) channels reflects strong volt- age dependence of channel block by intracellular cations such as polyamines. The voltage dependence results pri- marily from the movement of Kions across the transmembrane electric field, which accompanies the binding- unbinding of a blocker. Residues D172, E224, and E299 in IRK1 are critical for high-affinity binding

  10. Minimal Riesz energy point configurations for rectifiable d -dimensional manifolds

    Microsoft Academic Search

    D. P. Hardin; E. B. Saff

    2005-01-01

    We investigate the energy of arrangements of N points on a rectifiable d-dimensional manifold A?Rd? that interact through the power law (Riesz) potential V=1\\/rs, where s>0 and r is Euclidean distance in Rd?. With Es(A,N) denoting the minimal energy for such N-point configurations, we determine the asymptotic behavior (as N??) of Es(A,N) for each fixed s?d. Moreover, if A has

  11. Gravure printed organic rectifying diodes operating at high frequencies

    Microsoft Academic Search

    Kaisa E. Lilja; Tomas G. Bäcklund; Donald Lupo; Tomi Hassinen; Timo Joutsenoja

    2009-01-01

    Organic rectifier diodes operating at 10MHz made using roll-to-roll compatible mass printing processes to define patterns and deposit inks are reported. The diodes consist of a layer of poly(triarylamine) sandwiched between layers of silver and copper. No high resolution prepatterning of any surfaces was performed, thus the entire process could be carried out on large-scale roll-to-roll production lines. The organic

  12. Integrated high-quality rectifier-regulators

    Microsoft Academic Search

    Michael T. Madigan; Robert W. Erickson; Esam Hamid Ismail

    1999-01-01

    A new family of AC-DC converters is derived which integrate the functions of low-harmonic rectification, low-frequency energy storage, and wide-bandwidth output voltage control into a single converter containing one, two, or four active switches. These converters utilize a discontinuous conduction mode input inductor, an internal energy storage capacitor, and transformer secondary circuits which resemble the bridge, forward, flyback, or Cuk

  13. Controlled synthesis and growth of perfect platinum nanocubes using a pair of low-resistivity fastened silicon wafers and their electrocatalytic properties

    Microsoft Academic Search

    Jitendra N. Tiwari; Rajanish N. Tiwari; Kunlin Lin

    2011-01-01

    Perfect platinum (Pt) nanocubes with high density have been synthesized by controlled reduction of hexachloroplatinic acid\\u000a in the presence of H2SO4 and HCl, employing a pair of low-resistivity fastened silicon (FS) wafers at room temperature. The presence of the additive\\u000a charges (induced by prior etching of the silicon surface with HF to remove any SiO2 layer) between the interfaces of

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

    SciTech Connect

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

    2010-03-01

    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.

  15. The properties of polycrystalline silicon solar cells with controlled titanium additions

    NASA Technical Reports Server (NTRS)

    Rohatgi, A.; Hopkins, R. H.; Davis, J. R., Jr.

    1981-01-01

    By coupling the results of electrical measurements, such as spectral response, lighted and dark I-V determinations, and deep-level-transient spectroscopy with optical and laser scan photomicroscopy, the effects of grain boundaries and impurities on silicon solar cells were evaluated. Titanium, which produces two deep levels in silicon, degrades cell performance by reducing bulk lifetime and thus cell short-circuit current. Electrically active grain boundaries induce carrier recombination in the bulk and depletion regions of the solar cell. Experimental data imply a small but measurable segregation of titanium into some grain boundaries of the polycrystalline silicon containing high Ti concentration. However, for the titanium-contaminated polycrystalline material used in this study, solar cell performance is dominated by the electrically active titanium concentration in the grains. Microstructural impacts on the devices are of secondary importance

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

    PubMed Central

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

    2013-01-01

    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

  17. An Adaptive Reconfigurable Active Voltage Doubler/Rectifier for Extended-Range Inductive Power Transmission

    PubMed Central

    Lee, Hyung-Min; Ghovanloo, Maysam

    2014-01-01

    We present an adaptive reconfigurable active voltage doubler (VD)/rectifier (REC) (VD/REC) in standard CMOS, which can adaptively change its topology to either a VD or a REC by sensing the output voltage, leading to more robust inductive power transmission over an extended range. Both active VD and REC modes provide much lower dropout voltage and far better power conversion efficiency (PCE) compared to their passive counterparts by adopting offset-controlled high-speed comparators that drive the rectifying switches at proper times in the high-frequency band. We have fabricated the active VD/REC in a 0.5-µm 3-metal 2-poly CMOS process, occupying 0.585 mm2 of chip area. In an exemplar setup, VD/REC extended the power transmission range by 33% (from 6 to 8 cm) in relative coil distance and 41.5% (from 53° to 75°) in relative coil orientation compared to using the REC alone. While providing 3.1-V dc output across a 500-? load from 2.15- (VD) and 3.7-V (REC) peak ac inputs at 13.56 MHz, VD/REC achieved measured PCEs of 70% and 77%, respectively. PMID:24633369

  18. RF rectifiers for EM power harvesting in a Deep Brain Stimulating device.

    PubMed

    Hosain, Md Kamal; Kouzani, Abbas Z; Tye, Susannah; Kaynak, Akif; Berk, Michael

    2015-03-01

    A passive deep brain stimulation (DBS) device can be equipped with a rectenna, consisting of an antenna and a rectifier, to harvest energy from electromagnetic fields for its operation. This paper presents optimization of radio frequency rectifier circuits for wireless energy harvesting in a passive head-mountable DBS device. The aim is to achieve a compact size, high conversion efficiency, and high output voltage rectifier. Four different rectifiers based on the Delon doubler, Greinacher voltage tripler, Delon voltage quadrupler, and 2-stage charge pumped architectures are designed, simulated, fabricated, and evaluated. The design and simulation are conducted using Agilent Genesys at operating frequency of 915 MHz. A dielectric substrate of FR-4 with thickness of 1.6 mm, and surface mount devices (SMD) components are used to fabricate the designed rectifiers. The performance of the fabricated rectifiers is evaluated using a 915 MHz radio frequency (RF) energy source. The maximum measured conversion efficiency of the Delon doubler, Greinacher tripler, Delon quadrupler, and 2-stage charge pumped rectifiers are 78, 75, 73, and 76 % at -5 dBm input power and for load resistances of 5-15 k?. The conversion efficiency of the rectifiers decreases significantly with the increase in the input power level. The Delon doubler rectifier provides the highest efficiency at both -5 and 5 dBm input power levels, whereas the Delon quadrupler rectifier gives the lowest efficiency for the same inputs. By considering both efficiency and DC output voltage, the charge pump rectifier outperforms the other three rectifiers. Accordingly, the optimised 2-stage charge pumped rectifier is used together with an antenna to harvest energy in our DBS device. PMID:25600671

  19. Design of a nanomechanical fluid control valve based on functionalized silicon cantilevers: coupling molecular mechanics with classical engineering design

    NASA Astrophysics Data System (ADS)

    Solares, Santiago D.; Blanco, Mario; Goddard, William A., III

    2004-11-01

    Process engineering design relies on a host of mechanical devices that enable transport phenomena to take place under controlled conditions. These devices include pipes, valves, pumps, chemical reactors, heat exchangers, packed columns, etc. Mass, energy, and momentum transfer will also be essential phenomena in nanoprocess engineering, particularly at the interface between micro- and nanodevices. Control valves are one of the most fundamental components. In this paper we explore the design of a silicon cantilever valve for fluid transport control at the molecular level (34.5-70 nm in length). We utilize design elements that can be synthesized with existing or emerging chemical and solid state fabrication methods. Thus, the valve is constructed with functionalized silicon surfaces, single-wall carbon nanotubes, and organic monolayers. While molecular mechanics design limitations were overcome with help from classical engineering approximations, nonlinear effects, such as nanotube crimping (for an in-line valve design), are accounted for through full-physics atomistic simulations. Optimal design geometries and operating deflection ranges have been estimated for a device containing over 75 000 atoms.

  20. Growth control and properties of microcrystallized silicon films deposited by hydrogen plasma sputtering

    Microsoft Academic Search

    A. Achiq; R. Rizk; R. Madelon; F. Gourbilleau; P. Voivenel

    1997-01-01

    In this work, optical and electrical properties have been correlated to the degree of crystallization of silicon films deposited by sputtering in a pure H2 plasma at various substrate temperatures, Ts. On increasing Ts from 50 °C to 250 °C, the average grain size is found to grow from about 5 nm to some tens of nanometers, with a concomitant

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

    Microsoft Academic Search

    Abdullah Moinuddin; Jony C. Sarker; Akhter Zia

    2012-01-01

    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

  2. Microstructural control of porous silicon by electrochemical etching in mixed HCl\\/HF solutions

    Microsoft Academic Search

    S. Zangooie; R. Jansson; H. Arwin

    1998-01-01

    The role of hydrochloric acid in the fabrication of porous silicon was investigated with atomic force microscopy (AFM) and spectroscopic ellipsometry. The study was focused on surface morphology, in terms of roughness and power spectral density (PSD), and layer microstructure and quality in terms of thickness, porosity, interface sharpness and layer homogeneity. The results show that HCl can be used

  3. Low-power control techniques for silicon and organic circuits with array structures

    Microsoft Academic Search

    Hiroshi Kawaguchi

    2009-01-01

    In upcoming ubiquitous electronics environment, abundant electronics systems will be deployed in a sensor, car, robot, home, town, and even in a farm. The ubiquitous electronics support our comfortable and safe life, and thus require low-power feature. High-performance silicon VLSIs such as microprocessors will still be the mainstream also in the future ubiquitous electronics environment, as the modern life is

  4. A high-speed, tunable silicon photonic ring modulator integrated with ultra-efficient active wavelength control.

    PubMed

    Zheng, Xuezhe; Chang, Eric; Amberg, Philip; Shubin, Ivan; Lexau, Jon; Liu, Frankie; Thacker, Hiren; Djordjevic, Stevan S; Lin, Shiyun; Luo, Ying; Yao, Jin; Lee, Jin-Hyoung; Raj, Kannan; Ho, Ron; Cunningham, John E; Krishnamoorthy, Ashok V

    2014-05-19

    We report the first complete 10G silicon photonic ring modulator with integrated ultra-efficient CMOS driver and closed-loop wavelength control. A selective substrate removal technique was used to improve the ring tuning efficiency. Limited by the thermal tuner driver output power, a maximum open-loop tuning range of about 4.5nm was measured with about 14mW of total tuning power including the heater driver circuit power consumption. Stable wavelength locking was achieved with a low-power mixed-signal closed-loop wavelength controller. An active wavelength tracking range of > 500GHz was demonstrated with controller energy cost of only 20fJ/bit. PMID:24921379

  5. Physiological and molecular characterization of an IRK-type inward rectifier K+ channel in a tumour mast cell line.

    PubMed

    Wischmeyer, E; Lentes, K U; Karschin, A

    1995-04-01

    The basophilic leucaemia cell line RBL-2H3 exhibits a robust inwardly rectifying potassium current, IKIR, which is likely to be modulated by G proteins. We examined the physiological and molecular properties of this KIR conductance to define the nature of the underlying channel species. The macroscopic conductance revealed characteristics typical of classical K+ inward rectifiers of the IRK type. Channel gating was rapid, first order (tau approximately 1 ms at -100 mV) and steeply voltage dependent. Both activation potential and slope conductance were dependent on extracellular K+ concentration ([K+]o) and inward rectification persisted in the absence of internal Mg2+. The current was susceptible to a concentration- and voltage-dependent block by extracellular Na+, Cs+ and Ba2+. Initial IKIR whole-cell amplitudes as well as current rundown were dependent on the presence of 1 mM internal ATP. Perfusion of intracellular guanosine 5'-Q-(3-thiotriphosphate) (GTP[gamma S]) suppressed IKIR with an average half-time of decline of approximately 400 s. It was demonstrated that the dominant IRK-type 25 pS conductance channel was indeed suppressed by 100 microM preloaded GTP[gamma S]. Reverse transcriptase-polymerase chain reactions (RT-PCR) with RBL cell poly(A)+ RNA identified a full length K+ inward rectifier with 94% base pair homology to the recently cloned mouse IRK1 channel. It is concluded that RBL cells express a classical voltage-dependent IRK-type K+ inward rectifier RBL-IRK1 which is negatively controlled by G proteins. PMID:7603835

  6. High reliability megawatt transformer/rectifier

    NASA Technical Reports Server (NTRS)

    Zwass, Samuel; Ashe, Harry; Peters, John W.

    1991-01-01

    The goal of the two phase program is to develop the technology and design and fabricate ultralightweight high reliability DC to DC converters for space power applications. The converters will operate from a 5000 V dc source and deliver 1 MW of power at 100 kV dc. The power weight density goal is 0.1 kg/kW. The cycle to cycle voltage stability goals was + or - 1 percent RMS. The converter is to operate at an ambient temperature of -40 C with 16 minute power pulses and one hour off time. The uniqueness of the design in Phase 1 resided in the dc switching array which operates the converter at 20 kHz using Hollotron plasma switches along with a specially designed low loss, low leakage inductance and a light weight high voltage transformer. This approach reduced considerably the number of components in the converter thereby increasing the system reliability. To achieve an optimum transformer for this application, the design uses four 25 kV secondary windings to produce the 100 kV dc output, thus reducing the transformer leakage inductance, and the ac voltage stresses. A specially designed insulation system improves the high voltage dielectric withstanding ability and reduces the insulation path thickness thereby reducing the component weight. Tradeoff studies and tests conducted on scaled-down model circuits and using representative coil insulation paths have verified the calculated transformer wave shape parameters and the insulation system safety. In Phase 1 of the program a converter design approach was developed and a preliminary transformer design was completed. A fault control circuit was designed and a thermal profile of the converter was also developed.

  7. 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

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

    1996-01-01

    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

  8. Analysis and design of a novel single-phase full-bridge soft-switching rectifier

    Microsoft Academic Search

    Maoh-Chin Jiang; Shyh-Shing Perng; Chien-Ming Wang; Ter-Feng Wu; Ching-Hsien Ke; Jing-Jhu Jhan

    2009-01-01

    A novel single-phase full-bridge soft switching rectifier (FBSSR) using a new resonance unit is proposed in this paper. All main switches in the proposed soft switching rectifier operate at zero-voltage-switching (ZVS) turn-on and turn-off. Moreover, the auxiliary switches operate at zero-current-switching (ZCS) turn-on and turn-off. Major benefits of this novel rectifier are found in efficiency improvement, and reduced dv\\/dt. Besides,

  9. Circuit topologies for single-phase voltage-doubler boost rectifiers

    Microsoft Academic Search

    John C. Salmon

    1993-01-01

    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

  10. Soft-switched, high frequency resonant AC-to-DC rectifier with high power factor

    Microsoft Academic Search

    HYUN CHIL CHOI; JAE WON HAN; MYUNG JOONG YOUN

    1993-01-01

    A high frequency and soft-switched AC-to-DC rectifier employing a series-type resonant circuit is proposed to overcome the disadvantages of the conventional peak-rectifying circuit. Using the proposed rectifier, a high power factor and low harmonic currents are obtained in the AC line. Furthermore, several advantages such as high power density and wide output voltage range can also be available. Through simulation

  11. A Full-Wave Rectifier for Interfacing with Multi-Phase Piezoelectric Energy Harvesters

    Microsoft Academic Search

    N. J. Guilar; R. Amirtharajah; P. J. Hurst

    2008-01-01

    This paper describes an asynchronous full-wave rectifier for use with a multiple-electrode disk-shaped piezoelectric generator. By using quarter-circle shaped electrodes, similar to an ultrasonic motor, multiple output voltage phases are obtained from a single resonating piezoelectric disk. Two-electrode transducer outputs are often rectified using a full-wave diode bridge rectifier, which requires a significant voltage drop between input and output, decreasing

  12. A novel passive waveshaping method for single-phase diode rectifiers

    Microsoft Academic Search

    A. R. Prasad; P. D. Ziogas; S. Manias

    1990-01-01

    A novel passive waveshaping method for single-phase diode rectifiers is presented. It is shown that application of the proposed method maintains high-input power factor, lowers rectifier current stresses, and lowers the volt-ampere (VA) rating of the associated reactive components as compared to the standard diode rectifier. Relevant input and output current waveforms, component ratings, and power factor values are derived.

  13. Primary structure and characterization of a small-conductance inwardly rectifying potassium channel from human hippocampus.

    PubMed Central

    Périer, F; Radeke, C M; Vandenberg, C A

    1994-01-01

    We have isolated a human hippocampus cDNA that encodes an inwardly rectifying potassium channel, termed HIR (hippocampal inward rectifier), with strong rectification characteristics. Single-channel recordings indicate that the HIR channel has an unusually small conductance (13 pS), distinguishing HIR from other cloned inward rectifiers. RNA blot analyses show that HIR transcripts are present in heart, skeletal muscle, and several different brain regions, including the hippocampus. Images PMID:8016146

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

    SciTech Connect

    Zelenina, A., E-mail: anastasia.zelenina@imtek.uni-freiburg.de; Zacharias, M. [Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 103, Freiburg 79110 (Germany); Sarikov, A. [Faculty of Engineering, IMTEK, Albert-Ludwigs-University Freiburg, Georges-Köhler-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 für Solare Energiesysteme ISE, Heidenhofstr. 2, Freiburg 79110 (Germany); Zakharov, N.; Werner, P. [Max-Planck-Institute of Microstructure Physics, Weinberg 2, Halle 06120 (Germany); López-Conesa, L.; Peiró, F. [MIND-IN2UB, Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès, 1, Barcelona 08028 (Spain); Estradé, S. [MIND-IN2UB, Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès, 1, Barcelona 08028 (Spain); CCiT, Scientific and Technical Centers, Universitat de Barcelona, C/Lluís Solé 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

    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 2.5–12.5?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.

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

    DOEpatents

    Weiner, Kurt H. (San Jose, CA)

    2001-01-01

    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.

  16. Controlled release of theophylline from poly(vinyl alcohol) hydrogels/porous silicon nanostructured systems

    NASA Astrophysics Data System (ADS)

    Cervantes-Rincón, N.; Medellín-Rodríguez, F. J.; Escobar-Barrios, V. A.; Palestino, G.

    2013-03-01

    In this research, hybrid hydrogels of poly (vinyl alcohol)/ porous silicon (PSi)/theophylline were synthesized by the freezing and thawing method. We evaluated the influence of the synthesis parameters of the poly (vinyl alcohol) (PVA) hydrogels in relation to their ability to swell and drug released. The parameters studied (using an experimental design developed in Minitab 16) were the polymer concentration, the freezing temperature and the number of freezing/thawing (f/t) cycles. Nanostructured porous silicon particles (NsPSi) and theophylline were added within the polymer matrix to increase the drug charge and the polymer mechanical strength. The hybrid hydrogels were characterized by Infrared Spectroscopy Fourier Transform (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Differential Scanning Calorimetry (DSC), drug delivery kinetics were engineered according to the desired drug release schedule.

  17. Crystallization control of the amorphous buffer layer in hydrogenated nanocrystalline silicon

    Microsoft Academic Search

    F. Gourbilleau; A Achiq; P Voivenel; R Rizk

    1999-01-01

    Hydrogenated nanocrystalline silicon film have been deposited by RF sputtering in a pure hydrogen plasma at a substrate temperature of 150°C. The unintentionally grown amorphous buffer layer was almost completely crystallized at an annealing temperature as low as 150°C. By combining infrared absorption measurements and electron microscopy observations, the critical role of dihydride species, Si?H2, in the crystallization process have

  18. Novel synthetic methodology for controlling the orientation of zinc oxide nanowires grown on silicon oxide substrates.

    PubMed

    Cho, Jinhyun; Salleh, Najah; Blanco, Carlos; Yang, Sungwoo; Lee, Chul-Jin; Kim, Young-Woo; Kim, Jungsang; Liu, Jie

    2014-04-01

    This study presents a simple method to reproducibly obtain well-aligned vertical ZnO nanowire arrays on silicon oxide (SiOx) substrates using seed crystals made from a mixture of ammonium hydroxide (NH4OH) and zinc acetate (Zn(O2CCH3)2) solution. In comparison, high levels of OH(-) concentration obtained using NaOH or KOH solutions lead to incorporation of Na or K atoms into the seed crystals, destroying the c-axis alignment of the seeds and resulting in the growth of misaligned nanowires. The use of NH4OH eliminates the metallic impurities and ensures aligned nanowire growth in a wide range of OH(-) concentrations in the seed solution. The difference of crystalline orientations between NH4OH- and NaOH-based seeds is directly observed by lattice-resolved images and electron diffraction patterns using a transmission electron microscope (TEM). This study obviously suggests that metallic impurities incorporated into the ZnO nanocrystal seeds are one of the factors that generates the misaligned ZnO nanowires. This method also enables the use of silicon oxide substrates for the growth of vertically aligned nanowires, making ZnO nanostructures compatible with widely used silicon fabrication technology. PMID:24584438

  19. Rectifying calibration error of Goldmann applanation tonometer is easy!

    PubMed Central

    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

    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 didn’t 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

  20. Fabrication of periodic silicon nanopillars in a two-dimensional hexagonal array with enhanced control on structural dimension and period.

    PubMed

    Choi, Jea-Young; Alford, T L; Honsberg, Christiana B

    2015-04-01

    We present a method to fabricate well-controlled periodic silicon nanopillars (Si NPs) in hexagonal arrays using silica nanosphere (SNS) lithography (SNL) combined with metal-assisted chemical etching (MaCE). The period of the Si NPs is easily changed by using our silica nanosphere (SNS) spin-coating process, which provides excellent monolayer uniformity and coverage (>95%) over large surface areas. The size of the deposited SNS is adjusted by reactive ion etching (RIE) to produce a target diameter at a fixed period for control of the surface pattern size after a gold metal mask layer deposition. The Si NPs are etched with the MaCE technique following introduction of a Ni interfacial layer between the Si and Au catalyst layer for adhesion and improved lithographical accuracy. The result is a fast, convenient, and large-area applicable Si surface nanolithography technique for accurate and reproducible Si NP fabrication. PMID:25781034

  1. A Novel Solid-State Thermal Rectifier Based On Reduced Graphene Oxide

    PubMed Central

    Tian, He; Xie, Dan; Yang, Yi; Ren, Tian-Ling; Zhang, Gang; Wang, Yu-Feng; Zhou, Chang-Jian; Peng, Ping-Gang; Wang, Li-Gang; Liu, Li-Tian

    2012-01-01

    Recently, manipulating heat transport by phononic devices has received significant attention, in which phonon – a heat pulse through lattice, is used to carry energy. In addition to heat control, the thermal devices might also have broad applications in the renewable energy engineering, such as thermoelectric energy harvesting. Elementary phononic devices such as diode, transistor and logic devices have been theoretically proposed. In this work, we experimentally create a macroscopic scale thermal rectifier based on reduced graphene oxide. Obvious thermal rectification ratio up to 1.21 under 12?K temperature bias has been observed. Moreover, this ratio can be enhanced further by increasing the asymmetric ratio. Collectively, our results raise the exciting prospect that the realization of macroscopic phononic device with large-area graphene based materials is technologically feasible, which may open up important applications in thermal circuits and thermal management. PMID:22826801

  2. Silicone metalization

    DOEpatents

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

    2008-12-09

    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.

  3. Silicone metalization

    SciTech Connect

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

    2006-12-05

    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.

  4. On the Switched-Reluctance Motor Drive With Three-Phase Single-Switch Switch-Mode Rectifier Front-End

    Microsoft Academic Search

    Jui-Yuan Chai; Yuan-Chih Chang; Chang-Ming Liaw

    2010-01-01

    This paper presents a switched reluctance motor (SRM) drive powered by a three-phase single-switch (3P1SW) switch-mode rectifier (SMR). The digital controls of both power stages are realized in a common DSP. In the front-end SMR, a robust current harmonic cancellation scheme and a robust voltage control scheme are developed. The undesired line current and output voltage ripples are regarded as

  5. High-stroke silicon-on-insulator MEMS nanopositioner: control design for non-raster scan atomic force microscopy.

    PubMed

    Maroufi, Mohammad; Fowler, Anthony G; Bazaei, Ali; Moheimani, S O Reza

    2015-02-01

    A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10??m. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics of the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20??m × 20??m. The maximum scan rate demonstrated is 1?kHz. PMID:25725850

  6. High-stroke silicon-on-insulator MEMS nanopositioner: Control design for non-raster scan atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Maroufi, Mohammad; Fowler, Anthony G.; Bazaei, Ali; Moheimani, S. O. Reza

    2015-02-01

    A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10 ?m. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics of the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20 ?m × 20 ?m. The maximum scan rate demonstrated is 1 kHz.

  7. Controlling the shape and gap width of silicon electrodes using local anodic oxidation and anisotropic TMAH wet etching

    NASA Astrophysics Data System (ADS)

    Rouhi, Jalal; Mahmud, Shahrom; Derita Hutagalung, Sabar; Naderi, Nima; Kakooei, Saeid; Johar Abdullah, Mat

    2012-06-01

    A simple method for fabricating silicon electrodes with various shapes and gap widths was designed using the special properties of anisotropic tetramethylammonium hydroxide (TMAH) wet etching and local anodic oxidation (LAO). A statistical system was used for the optimization of the parameters of the LAO process to facilitate a better understanding and precise analysis of the process. Analyses of the interaction effects among the significant factors of LAO showed that the relative humidity and applied voltage were interdependent. They had the strongest interaction effect on the dimensions of the oxide mask. TMAH with a concentration of 25% was used as an etchant solution in (1?0?0) silicon with a rectangular oxide mask. The observed undercutting at convex corners, tip shape of emitters and gap widths of electrodes were exactly consistent with theoretical studies. Combination of the LAO method and anisotropic TMAH wet etching was successfully used to fabricate Si nano-gap electrodes. This fabrication method of sharp and round tip emitters was simple, controllable and faster than common techniques. These results indicate that the method can be a new approach for studying the electrical properties of nano-gap electrodes.

  8. Ionic conductances in frog short skeletal muscle fibres with slow delayed rectifier currents.

    PubMed

    Lynch, C

    1985-11-01

    Short (0.8-1.6 mm) lumbricalis fibres of Rana pipiens were voltage clamped by a two-micro-electrode technique at 5 degrees C in sucrose hypertonic Ringer solution (SHR). Terminated linear cable analysis suggests that if the current electrode is placed near the centre of the fibre length and the voltage-sensing electrode is placed 0.19 times the fibre length from the current electrode, the fibre can be adequately voltage clamped and the conductance may be simply calculated as I/V for fibre length constants from 1.0 to 0.15 mm. In SHR solution lumbricalis fibres have action potentials with peak amplitudes of only +2 to 7 mV and a slow, gradual repolarization, distinct from the action potentials observed in sartorius muscle. In 60 mM-Na+ SHR the inward Na current could be adequately controlled over the fibre length, providing an estimated Na conductance (GNa) of 8.9 mS/cm2. The magnitude of GNa and GK (delayed rectifier) in lumbricalis fibres was approximately 20% of that reported for sartorius and semitendinosus, although the resting conductances were similar. Fibres demonstrated delayed rectifier currents with complex patterns of activation suggesting two components of conductance (fast, GK,f and slow, GK,s) which were combined together in varied amounts: (a) GK,f activated rapidly to a maximum within 80 ms at 0 mV as previously described (Adrian, Chandler & Hodgkin, 1970a); (b) GK,s activated gradually with depolarizations below -50 mV and achieving peak currents at about 400 ms at 0 mV. In about 10% of lumbricalis fibres studied, GK,s occurred in isolation with a peak magnitude of 1.4 +/- 0.4 mS/cm2 (+/- S.D.). GK,s activation kinetics and tail currents are described by a squared two-state (l2) Hodgkin-Huxley model and have a Q10 of 2.8. These currents inactivated with a time constant of 5-7 s at 0 mV. Isolated GK,s with identical kinetics was also observed in certain sartorius fibres studied with the three-electrode voltage clamp. The fractional amount of GK,s in the combined delayed rectifier (GK,s + GK,f) currents could be estimated from analysis of the late activation phase with depolarization. Combined delayed currents were described by summing GK,f currents using a n4 model with GK,s currents defined by the l2 model. PMID:2416916

  9. Structural control over equilibrium silicon and oxygen isotopic fractionation: A first-principles density-functional theory study

    Microsoft Academic Search

    Merlin Méheut; Michele Lazzeri; Etienne Balan; Francesco Mauri

    2009-01-01

    Isotopic fractionation factors for oxygen and silicon in selected silicates (quartz, enstatite, forsterite, lizardite, kaolinite) are calculated using first-principles methods based on density-functional theory. Good agreement between theory and experiment is found in the case of oxygen. In the case of silicon, agreement and differences with existing estimates of equilibrium fractionation factors are discussed. The relationship between silicon and oxygen

  10. New 24-pulse diode rectifier systems for utility interface of high-power AC motor drives

    Microsoft Academic Search

    Sewan Choi; Bang Sup Lee; Prasad N. Enjeti

    1997-01-01

    This paper proposes two new passive 24-pulse diode rectifier systems for utility interface of pulsewidth modulated (PWM) AC motor drives. The first approach employs an extended delta transformer arrangement, which results in near equal leakage inductance in series with each diode rectifier bridge. This promotes equal current sharing and improved performance. A specially tapped interphase transformer is then introduced with

  11. Physical Layout of High Current Rectifiers: Modern Methods for an Old Challenge

    Microsoft Academic Search

    J. L. Schanen; J. M. Guichon; C. Domenech; L. Meysenc

    2008-01-01

    This paper address some problems linked to the physical layout of high current rectifier: paralleling components, magnetic field close to the rectifier and also the validation of the physical layout at reduced current. Even if the impact of cabling stray inductance is well known, some new tools and methodology are today available to design quicker and safer the physical layout

  12. A Novel Cl Inward-Rectifying Current in the Plasma Membrane of the Calcifying Marine Phytoplankton

    E-print Network

    Taylor, Alison

    rectifier that tightly regulates membrane potential. Membrane depolarization gave rise to nonselectiveA Novel Cl Inward-Rectifying Current in the Plasma Membrane of the Calcifying Marine Phytoplankton Kingdom, The Laboratory, Citadel Hill, Plymouth PL1 2PB, United Kingdom We investigated the membrane

  13. A high density 48 V 200 A rectifier with power factor correction-an engineering overview

    Microsoft Academic Search

    D. Chapman; D. James; C. J. Tuck

    1993-01-01

    In telecommunications installations it is desirable for power equipment to draw a balanced three phase current at unity power factor with zero neutral current. A compact 48 V, 200 A rectifier weighing 32 kg has been commercially developed for this need. The rectifier employs the power conversion techniques first reported at INTELEC 1989 by Dennis Chapman of Swichtec Power Systems

  14. Harmonic Analysis of a Three-Phase Diode Bridge Rectifier based on Sampled-Data Model

    E-print Network

    Lehn, Peter W.

    Harmonic Analysis of a Three-Phase Diode Bridge Rectifier based on Sampled-Data Model K. L. Lian is to incorporate it into a harmonic power flow program to yield improved accuracy. Index Terms-- Diode Bridge. INTRODUCTION THREE phase diode bridge rectifiers are often used in industry to provide the dc input voltage

  15. A novel single-phase HPF hybrid rectifier suitable for front-end trolleybus systems

    Microsoft Academic Search

    Luiz C. G. Freitas; Gustavo B. Lima; F. A. S. Gonalves; Guilherme A. Melo; Carlos A. Canesin

    2009-01-01

    This paper proposal presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements

  16. The Stoichiometry of G Binding to G-protein-regulated Inwardly Rectifying K Channels (GIRKs)*

    E-print Network

    Clapham, David E.

    The Stoichiometry of G Binding to G-protein-regulated Inwardly Rectifying K Channels (GIRKs, Boston, Massachusetts 02115 G-protein-coupled inwardly rectifying K (GIRK; Kir3.x) channels are the primary effectors of numerous G-protein-coupled receptors. GIRK channels decrease cellular excitability

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

    Microsoft Academic Search

    Xing-Yuan Li; O. P. Malik

    1994-01-01

    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

  18. Etched profile control in anisotropic etching of silicon by TMAH+Triton

    NASA Astrophysics Data System (ADS)

    Pal, Prem; Gosálvez, M. A.; Sato, K.

    2012-06-01

    The adverse effect of mechanical agitation (magnetic bead stirring) as well as galvanic interaction between the evolving facets of the etch front on the amount of undercutting during anisotropic etching of Si{1?0?0} wafers in surfactant-added tetramethylammonium hydroxide (TMAH) is studied by etching different mask patterns in magnetically stirred and nonstirred solutions. Triton X-100, with formula C14H22O(C2H4O)n, where n = 9-10, is used as the surfactant. The stirring results conclude that the adsorption of the surfactant on the etched silicon surfaces is predominantly physical in nature rather than chemical (physisorption versus chemisorption). The proposed model to account for the galvanic interaction between the evolving facets indicates that the underlying chemical etching process can be significantly surpassed by the onset of an electrochemical etching contribution when the relative area of the exposed {1?0?0} surface becomes relatively small in comparison to that of the developed {1?1?1} sidewalls. This study is useful for engineering applications where surfactant-added TMAH is used for the fabrication of silicon MEMS structures that should contain negligible undercutting.

  19. Memory characteristics of laser-crystallized polycrystalline-silicon silicon-oxide-nitride-oxide-silicon thin-film transistor with location-controlled grain boundary perpendicular to the channel

    NASA Astrophysics Data System (ADS)

    Lee, I.-Che; Tsai, Chun-Chien; Kuo, Hsu-Hang; Yang, Po-Yu; Wang, Chao-Lung; Cheng, Huang-Chung

    2012-06-01

    An excimer-laser-crystallized polycrystalline-silicon silicon-oxide-nitride-oxide-silicon thin-film transistor with recessed-channel structure has been designed to achieve only one grain boundary with a protrusion perpendicular to the channel for investigating the grain boundary location effects on the memory characteristics. After programming, the devices demonstrated better memory characteristics as the grain boundary was allocated near the source junction. In contrast, the memory characteristics were degraded when the grain boundary was located near the drain junction. The phenomenon was explained by the 2-D device simulation and the energy band diagrams.

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

    NASA Astrophysics Data System (ADS)

    Singh, B.; Rajesh, M.

    2013-09-01

    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.

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

    SciTech Connect

    Leahu, G. L., E-mail: roberto.livoti@uniroma1.it; Li Voti, R., E-mail: roberto.livoti@uniroma1.it; Larciprete, M. C., E-mail: roberto.livoti@uniroma1.it; Belardini, A., E-mail: roberto.livoti@uniroma1.it; Mura, F., E-mail: roberto.livoti@uniroma1.it; Sibilia, C.; Bertolotti, M. [Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16 00161 Roma (Italy); Fratoddi, I. [Dipartimento di Chimica, Sapienza Università di Roma, Piazzale A. Moro, Roma (Italy)

    2014-06-19

    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.

  2. A Prospective, Randomized, Placebo Controlled, Double Blind Study of Silicone Gel in Prevention of Hypertrophic Scar at Donor Site of Skin Grafting

    PubMed Central

    Chittoria, Ravi Kumar; Padi, Tirupathi Rao

    2013-01-01

    Background: Hypertrophic scarring at donor site of skin grafting is prevalent among Asians. The effectiveness of silicone gel in scar prevention may influence the surgeons and patients regarding its routine use during the postoperative period. Aims and Objectives: To study the efficacy of silicone gel in prevention of hypertrophic scars at donor site of skin grafting. Design: Prospective randomized placebo controlled double blind study. Setting: The study was conducted in the department of Plastic Surgery, Sri Venkateswara Institute of Medical Sciences (SVIMS) University, Tirupati, Andhra Pradesh, India from June 2007 to June 2009. Patients were recruited during follow-up in the OPD. Materials and Methods: The susceptibility to scar development varied among patients; therefore, donor site scars were divided into upper half and lower half. Two types of coded gel prepared by an independent pharmacist were used on either half. Thus, selection and assessment biases and confounders were eliminated. Results: 100 scars in 50 patients were randomized into two arms, 50 control and 50 silicone gel. The median age was 25.5 years and there were 30 men (60%) and 20 women (40%). Thirty-seven patients (74%) had good compliance. The overall incidence of donor site hypertrophic scar was 94% (47 out of 50). At the second month postoperatively, the silicone gel scars were scored lower when compared with the control scars. The differences were statistically significant in all parameters, including pigmentation (P = 0.001), Vascularity (P = 0.010), pliability (P = 0.001), and height (P = 0.010). Conclusion: The effect of silicone gel in prevention of hypertrophic scar development in donor site scars is promising. Success of silicone gel in its prophylactic role will create its routine use in all types of surgery to minimize the formation of hypertrophic scars in the early postoperative period. PMID:23723598

  3. Silicon microfluidic flow focusing devices for the production of size-controlled PLGA based drug loaded microparticles.

    PubMed

    Keohane, Kieran; Brennan, Des; Galvin, Paul; Griffin, Brendan T

    2014-06-01

    The increasing realisation of the impact of size and surface properties on the bio-distribution of drug loaded colloidal particles has driven the application of micro fabrication technologies for the precise engineering of drug loaded microparticles. This paper demonstrates an alternative approach for producing size controlled drug loaded PLGA based microparticles using silicon Microfluidic Flow Focusing Devices (MFFDs). Based on the precise geometry and dimensions of the flow focusing channel, microparticle size was successfully optimised by modifying the polymer type, disperse phase (Qd) flow rate, and continuous phase (Qc) flow rate. The microparticles produced ranged in sizes from 5 to 50 ?m and were highly monodisperse (coefficient of variation <5%). A comparison of Ciclosporin (CsA) loaded PLGA microparticles produced by MFFDs vs conventional production techniques was also performed. MFFDs produced microparticles with a narrower size distribution profile, relative to the conventional approaches. In-vitro release kinetics of CsA was found to be influenced by the production technique, with the MFFD approach demonstrating the slowest rate of release over 7 days (4.99 ± 0.26%). Finally, MFFDs were utilised to produce pegylated microparticles using the block co-polymer, PEG-PLGA. In contrast to the smooth microparticles produced using PLGA, PEG-PLGA microparticles displayed a highly porous surface morphology and rapid CsA release, with 85 ± 6.68% CsA released after 24h. The findings from this study demonstrate the utility of silicon MFFDs for the precise control of size and surface morphology of PLGA based microparticles with potential drug delivery applications. PMID:24680950

  4. Electron irradiation effect on minority carrier lifetime and other electrical characteristics in silicon power devices

    NASA Astrophysics Data System (ADS)

    Fuochi, P. G.; Di Marco, P. G.; Monti, A.; Bisio, G. M.; Di Zitti, E.; Passerini, B.; Tenconi, S.

    Irradiation of silicon power rectifiers with electrons of 12 MeV energy has been carried out. Minority carrier lifetime ?, forward voltage V F, reverse recovered charge Q RR, reverse recovery time t RR for the diodes, circuit commutated turn-off time t q, and on-state voltage V T for the thyristors are measured as a function of dose. Power diodes and thyristors obtained from <111> neutron transutation or phosphorus doped float-zone silicon slices having 120?cm and 65?cm starting resistivity respectively and Ga-diffused are irradiated at room temperature. A linear relationship between carrier lifetime of irradiated diodes and electron dose is found and the calculated damage coefficients are k ? = 1.1x10 -8 cm 2/s and 7.2x10 -9 cm 2/s for the low-level and high-level lifetimes respectively at 25°C. For irradiated thyristors the linear relationship between turn-off time and dose yields k tq = 3x10 -9 cm 2/s at 125°C. Electron irradiation also affects the resistivity of the starting n-type silicon, increasing it of ? 15?cm for radiation doses > 1×10 4 Gy. A dose rate effect on the electrical characteristics of the devices using pulses of different duration is analyzed. Annealing studies are carried out at 150 °C, 200°C and 360°C to assess the stability of the defects produced by the electron bombardment by monitoring the variation of the electrical characteristics of the irradiated devices in the temperature range of interest. DLTS measurements performed on electron irradiated power rectifiers have revealed a complex defect pattern. The E 1 defect level (E c-0.17 ev) is the principal recombination center that controls lifetime following room temperature irradiation. The energy levels and capture cross sections of these irradiation induced-defects are reported. This study confirms that lifetime control in silicon power devices is feasible by high energy electrons. The major advantages of this technique over metallic diffusion or 60Co ?-irradiation methods are: better quality, lower processing cost and higher device yields. Annealing after irradiation is important to ensure long-term device stability.

  5. Adjustable Lid Aids Silicon-Ribbon Growth

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  6. Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction

    PubMed Central

    Lee, Seok Woo; Lee, Hyun-Wook; Ryu, Ill; Nix, William D.; Gao, Huajian; Cui, Yi

    2015-01-01

    Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries. PMID:26112834

  7. Enhanced light absorption of amorphous silicon thin film by substrate control and ion irradiation

    PubMed Central

    2014-01-01

    Large-area periodically aligned silicon nanopillar (PASiNP) arrays were fabricated by magnetic sputtering with glancing angle deposition (GLAD) on substrates coated by a monolayer of close-packed polystyrene (PS) nanospheres. The structure of PASiNP arrays could be manipulated by changing the diameter of PS nanospheres. Enhanced light absorptance within a wavelength range from 300 to 1,000 nm was observed as the diameter of nanopillars and porosity of PASiNP arrays increased. Meanwhile, Xe ion irradiation with dose from 1?×?1014 to 50?×?1014 ions/cm2 was employed to modify the surface morphology and top structure of thin films, and the effect of the irradiation on the optical bandgap was discussed. PACS code 81.15.Cd; 78.66.Jg; 61.80.Jh PMID:24717078

  8. 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

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

    PubMed

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

    1999-01-01

    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

  10. Periodic silicon nanocones arrays with controllable dimensions prepared by two-step etching using nanosphere lithography and NH4OH\\/H2O2 solution

    Microsoft Academic Search

    Mingfei Yang; HongYu Yu; Xiaowei Sun; Junshuai Li; Xiaocheng Li; Lin Ke; Junhui Hu; Fei Wang; Zhihui Jiao

    2010-01-01

    An electroless chemical etching technique using polystyrene nanospheres as self-assembled mask is developed to fabricate size-controllable, periodic silicon nanopillars (NPs) and subsequent nanocones (NCs) arrays. The Si NCs are obtained based on the NPs structure using cost-effective ammonia-related etching chemistry. The diameter, height, and periodicity of the NCs can be systematically controlled. This method is potentially beneficial to many device

  11. D0 Silicon Upgrade: Control Dewar Steady State Thermodynamic Operating Goals

    Microsoft Academic Search

    Russ Rucincki

    1995-01-01

    This engineering note documents the thermodynamic operating parameter goals for the steady state operation of the control dewar\\/solenoid system. Specifically, how the control dewar pressure control valve, PV-3062-H and the magnet flow control valve EVMF are operated to give the lowest possible temperature fluid at the solenoid magnet. The goals are: (1) For PV-3062-H - The process variable is the

  12. Robust reproducible large-area molecular rectifier junctions

    NASA Astrophysics Data System (ADS)

    Che, Hui-Juan; Chia, Perq-Jon; Chua, Lay-Lay; Sivaramakrishnan, Sankaran; Tang, Jie-Cong; Wee, Andrew T. S.; Chan, Hardy S. O.; Ho, Peter K. H.

    2008-06-01

    Stable rectifying molecular junctions have been obtained by sandwiching self-assembled monolayer films containing "push-pull" donor-?-acceptor (D-?-A) moieties between Au and poly(3,4-ethylenedioxythiophene) electrodes. These D-?-A moieties possess moderate molecular dipoles, but assemble into films with nearly zero dipole moment due to adoption of high average tilt angles. Nevertheless reproducible and well-behaved rectifications (ratio up to 3.3) in the expected polarity were obtained. At low biases, the current-voltage characteristics follow Simmon's tunneling theory with reasonable barrier heights and an effective tunnel mass of ˜0.5me. This suggests that asymmetric tunneling, and not carrier injection, is the origin of the rectification.

  13. Seismic triggering by rectified diffusion in geothermal systems

    NASA Astrophysics Data System (ADS)

    Sturtevant, Bradford; Kanamori, Hiroo; Brodsky, Emily E.

    1996-11-01

    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 system modeled as a two-component H2O-CO2 fluid in porous rock the pressure initially increases linearly with time. The rate of pressure buildup depends sensitively on the mean bubble radius and is large for small bubbles. The diffusion-induced pressure is relaxed by percolation and resorption of vapor into the liquid solution. The induced seismicity itself also relieves stress. Values of parameters used in the present calculations give results consistent with observations of triggered seismicity at Long Valley caldera after the Landers earthquake. For one representative condition, at 250°C and 5.6 km depth, oscillating strain acting on 10-?m-diameter bubbles increases pore pressure at the rate of 151 Pa/s resulting in a pressure increase of 12 kPa in the 80-s duration of the Landers earthquake. The elevated pressure induced by a single 26-m-diameter cloud of bubbles in saturated rock relaxes by percolation through soil of 0.2-mdarcy permeability in 53.6 hours. Observations of earthquake swarms at other locations suggest that self-induced buildup of pore pressure by rectified diffusion can provide a positive feedback mechanism for amplifying seismicity.

  14. Silicone Granuloma

    Microsoft Academic Search

    B. H. Krayenbühl; R. G. Panizzon

    2000-01-01

    Since silicone has rapidly become one of the most commonly used prosthetic materials in the last 30 years in modern medicine, we have consequently been witnessing more silicone-related disease. Especially after silicone breast implantation, defects in the breast implant have led to serious complications, whereas complications of silicone prosthesis implantation in other body parts are less frequent. Here we present

  15. Novel High Frequency Planner Transformer Linked Soft Switching DC-DC Power Converter with Secondary Side-Phase Shifted PWM Active Rectifying Switches

    Microsoft Academic Search

    N. A. Ahmed; M. Miyatake; K. Nishimura; Hyun-Woo Lee; M. Nakaoka

    2005-01-01

    This paper presents a novel circuit topology of isolated DC-DC power converter, which includes stable and efficient zero voltage soft switching (ZVS) full bridge inverter in the high frequency planner transformer primary-side and zero current soft switching rectifier in its secondary side. This power converter incorporates zero current soft switching (ZCS) phase-shifted PWM controlled two active power switches in series

  16. Silicon-silicon interfaces

    NASA Astrophysics Data System (ADS)

    Redfield, D.

    1982-01-01

    A wide variety of measurements on silicon grain boundaries shows that the electronic properties of such boundaries are much like those of Si surfaces in all essential respects. Moreover, the properties of 'clean' surfaces and lightly contaminated surfaces can be studied on many crystallographic orientations of the interfaces without the need for vacuum measurements. Such grain boundaries may therefore be regarded as Si-Si interfaces in the sense used in surface physics. It is shown that the thermal history and the dissolved oxygen of the silicon play major roles in determining the interface properties.

  17. Sputtered iron oxide/silicon heterostructures

    NASA Astrophysics Data System (ADS)

    Kardauskas, M. J.; Fonash, S. J.; Ashok, S.; Krishnaswamy, S. V.; Messier, R. F.

    1981-03-01

    Sputtered Fe3O4 films are shown to form rectifying junctions to p-type silicon but ohmic contacts to n-type Si. It is pointed out that ohmic contacts to the Fe3O4 can be provided by Au, Al, or spray-deposited ITO. The redox couple Fe(CN)6(3-)/Fe(CN)6(4-) also seems to make an effective ohmic contact to this iron oxide. It is found that the photovoltaic and electrical characteristics of the Fe3O4/p-Si heterojunction depend strongly on the Fe3O4 film thickness.

  18. ON THE INFLUENCE OF RECOMBINATION CENTERS ON THE ELECTRICAL PERFORMANCE OF SILICON POWER RECTIFIERS

    E-print Network

    Paris-Sud XI, Université de

    are more often considered. In this paper, we present a more rigorous approach of the case of amphoteric with an elementary recombination rate Ui and the effective lifetime is 1.2 AMPHOTERIC CENTERS. - Consider now

  19. Controlled Synthesis of Millimeter-Long Silicon Nanowires with Uniform Electronic Properties

    PubMed Central

    Park, Won Il; Zheng, Gengfeng; Jiang, Xiaocheng; Tian, Bozhi; Lieber, Charles M.

    2009-01-01

    We report the nanocluster-catalyzed growth of ultra-long and highly-uniform single-crystalline silicon nanowires (SiNWs) with millimeter-scale lengths and aspect ratios up to ca. 100,000. The average SiNW growth rate using disilane (Si2H6) at 400 °C was 31 µm/min, while the growth rate determined for silane (SiH4) reactant under similar growth conditions was 130 times lower. Transmission electron microscopy studies of millimeter-long SiNWs with diameters of 20–80 nm show that the nanowires grow preferentially along the <110> direction independent of diameter. In addition, ultra-long SiNWs were used as building blocks to fabricate one-dimensional arrays of field-effect transistors (FETs) consisting of ca. 100 independent devices per nanowire. Significantly, electrical transport measurements demonstrated that the millimeter-long SiNWs had uniform electrical properties along the entire length of wires, and each device can behave as a reliable FET with an on-state current, threshold voltage, and transconductance values (average ± 1 standard deviation) of 1.8 ± 0.3 µA, 6.0 ± 1.1 V, 210 ± 60 nS, respectively. Electronically-uniform millimeter-long SiNWs were also functionalized with monoclonal antibody receptors, and used to demonstrate multiplexed detection of cancer marker proteins with a single nanowire. The synthesis of structurally- and electronically-uniform ultra-long SiNWs may open up new opportunities for integrated nanoelectronics, and could serve as unique building blocks linking integrated structures from the nanometer through millimeter length scales. PMID:18710294

  20. Controlled nucleation and growth process for large grained polycrystalline silicon photovoltaics

    E-print Network

    Danforth, Stephen C.

    1982-01-01

    Research has been conducted to develop a new means of producing large grained polycrystlline thin films for photovoltaic applications. The process is one of growth of controlled crystalline nuclei in an a-Si film. For this ...

  1. Materials Science and Engineering B 134 (2006) 282286 Control of metal impurities in "dirty" multicrystalline silicon for solar cells

    E-print Network

    2006-01-01

    of silicon used) of the cost of processed solar cells, which has a major impact on the competitiveness" multicrystalline silicon for solar cells A.A. Istratova,b,, T. Buonassisia,b,1, M.D. Picketta,b, M. Heuera,b, E processing of solar cells with satisfactory energy conversion efficiency based on inexpensive feedstock

  2. Intravitreal controlled release of dexamethasone from engineered microparticles of porous silicon dioxide.

    PubMed

    Wang, Chengyun; Hou, Huiyuan; Nan, Kaihui; Sailor, Michael J; Freeman, William R; Cheng, Lingyun

    2014-12-01

    Dexamethasone is a glucocorticoid that is widely used in the ophthalmic arena. The recent FDA approved dexamethasone implant can provide a three month efficacy but with high rate of drug related cataract and high intraocular pressure (IOP). It seems that higher steroid in aqueous humor and around lens may be associated with these complications based on clinical fact that higher IOP was observed with intravitreal triamcinolone acetonide (TA) than with subtenon TA. We hypothesize that placing a sustained dexamethasone release system near back of the eye through a fine needle can maximize efficacy while mitigate higher rate of IOP rise and cataract. To develop a sustained intravitreal dexamethasone delivery system, porous silicon dioxide (pSiO2) microparticles were fabricated and functionalized with amines as well as carboxyl groups. Dexamethasone was conjugated to pSiO2 through the Steglich Esterification Reaction between hydroxyl of dexamethasone and carboxyl groups on the pSiO2. The drug loading was confirmed by Fourier transform infrared spectroscopy (FTIR) and loading efficiency was quantitated using thermogravimetric analysis (TGA). In vitro release was conducted for three months and dexamethasone was confirmed in the released samples using liquid chromatography-tandem mass spectrometry (LC/MS/MS). A pilot ocular safety and determination of vitreous drug level was performed in rabbit eyes. The drug loading study demonstrated that loading efficiency was from 5.96% to 10.77% depending on the loading reaction time, being higher with longer loading reaction time before reaching saturation around 7 days. In vitro drug release study revealed that dexamethasone release from pSiO2 particles was sustainable for over 90 days and was 80 days longer than free dexamethasone or infiltration-loaded pSiO2 particle formulation in the same setting. Pilot in vivo study demonstrated no sign of ocular adverse reaction in rabbit eyes following a single 3 mg intravitreal injection and free drug level at 2-week was 107.23 ± 10.54 ng/mL that is well above the therapeutic level but only around 20% level of dexamethasone released from OZURDEX(®) (dexamethasone intravitreal implant) in a rabbit eye model. In conclusion, dexamethasone is able to covalently load to the pSiO2 particles and provide sustained drug release for at least 3 months in vitro. Intravitreal injection of these particles were well tolerated in rabbit eyes and free drug level in vitreous at 2-week was well above the therapeutic level. PMID:25446320

  3. A Full-Wave Rectifier With Integrated Peak Selection for Multiple Electrode Piezoelectric Energy Harvesters

    Microsoft Academic Search

    Nathaniel J. Guilar; Rajeevan Amirtharajah; Paul J. Hurst

    2009-01-01

    Piezoelectric transducers are a viable way of harvesting vibrational energy for low power embedded systems such as wireless sensors. A proposed disk-shaped piezoelectric transducer with several electrodes enables increased energy harvesting from multiple mechanical resonances. To rectify the low-frequency AC voltage from harvested vibrational energy, a full-wave rectifier has been fabricated in 0.35 mum CMOS. Integrated peak selection circuitry allows

  4. An Efficient Piezoelectric Energy Harvesting Interface Circuit Using a Bias-Flip Rectifier and Shared Inductor

    Microsoft Academic Search

    Yogesh K. Ramadass; Anantha P. Chandrakasan

    2010-01-01

    Harvesting ambient vibration energy through piezoelectric means is a popular energy harvesting technique which can potentially supply 10-100's of ¿W of available power. One of the main limitations of existing piezoelectric harvesters is in their interface circuitry. In this paper, a bias-flip rectifier circuit that can improve the power extraction capability from piezoelectric harvesters over conventional full-bridge rectifiers and voltage

  5. Adding rectifying\\/stripping section type heat integration to a pressure-swing distillation (PSD) process

    Microsoft Academic Search

    Kejin Huang; Lan Shan; Qunxiong Zhu; Jixin Qian

    2008-01-01

    This paper studies the economical effect of considering rectifying\\/stripping section type heat integration in a pressure-swing distillation (PSD) process separating a binary homogeneous pressure-sensitive azeotrope. The schemes for arranging heat integration between the rectifying section and the stripping section of the high- and low-pressure distillation columns, respectively, are derived and an effective procedure is devised for the conceptual process design

  6. Growth by rectified diffusion of strongly acoustically forced gas bubbles in nearly saturated liquids

    Microsoft Academic Search

    Olivier Louisnard; Francisco Gomez

    2003-01-01

    The growth or dissolution of small gas bubbles (R0<15 mum) by rectified diffusion in nearly saturated liquids, subject to low frequencies (20 kHzrectified diffusion threshold radius merges with the Blake threshold radius, which means that a growing bubble is

  7. Control of Ring Magnet Current of the Zero Gradient Synchrotron at Argonne National Laboratory

    Microsoft Academic Search

    W. F. Praeg

    1965-01-01

    A comprehensive account is given of the control of the ring magnet current for the 12.5 BeV Zero Gradient Synchrotron (ZGS) at Argonne National Laboratory. Pulsing power is supplied by a motor-generator-flywheel set via four groups of 12-phase rectifiers. The rectifier groups operate alternately as power rectifiers and power inverters as directed by their phase control circuits.

  8. A dual-gate-controlled single-electron transistor using self-aligned polysilicon sidewall spacer gates on silicon-on-insulator nanowire

    Microsoft Academic Search

    Shu-Fen Hu; Yung-Chun Wu; Chin-Lung Sung; Chun-Yen Chang; Tiao-Yuan Huang

    2004-01-01

    A dual-gate-controlled single-electron transistor was fabricated by using self-aligned polysilicon sidewall spacer gates on a silicon-on-insulator nanowire. The quantum dot formed by the electric field effect of the dual-gate structure was miniaturized to smaller than the state-of-the-art feature size, through a combination of electron beam lithography, oxidation, and polysilicon sidewall spacer gate formation processes. The device shows typical MOSFET I-V

  9. Controlled aluminum-induced crystallization of an amorphous silicon thin film by using an oxide-layer diffusion barrier

    NASA Astrophysics Data System (ADS)

    Hwang, Ji-Hyun; Kwak, Hyunmin; Kwon, Myeung Hoi

    2014-03-01

    Aluminum-induced crystallization (AIC) of amorphous silicon with an Al2O3 diffusion barrier was investigated for controlling Si crystallization and preventing layer exchange during the annealing process. An Al2O3 layer was deposited between the a-Si and the Al films (a-Si/Al2O3/Al/Glass) and was blasted with an air spray gun with alumina beads to form diffusion channels between the Si and the Al layers. During the annealing process, small grain Si x Al seeds were formed at the channels. Then, the Al2O3 diffusion barrier was restructured to close the channels and prevent further diffusion of Al atoms into the a-Si layer. A polycrystalline Si film with (111), (220) and (311) crystallization peaks in the X-ray diffraction pattern was formed by annealing at 560 °C in a conventional furnace. That film showed a p-type semiconducting behavior with good crystallinity and a large grain size of up to 14.8 µm. No layer conversion occurred between the Si and the Al layers, which had been the fundamental obstacle to the applications in the crystallization of a-Si films by using the AIC method.

  10. Performance Analysis of Rectifier in NH3-H2O Absorprtion Heat Pump

    NASA Astrophysics Data System (ADS)

    Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige

    Heat and mass transfer model for plate-type rectifier was presented in the previous paper and it was found that there existed the distribution of NH3 concentration in boundary layer in vapor and solution phase, which was the resistance to heat and mass transfer. In order to enhance heat and mass transfer, packed tower-type rectifiers have been considered effective and used in the field of chemical engineering. And many data have been accumulated for each rectification-packing with give fluid to design packed tower. But it has rarely be seen to present heat and mass transfer model in order to evaluate the performance of packed tower rectifier without any experimental constant. In this study heat and mass transfer model in packed tower-type rectifier was presented considering the specification of rectification-packing decided by surface area and porosity, and the calculation results were compared with experimental data. As a result it was found that over-all mass transfer coefficient increased as mass flow rate of vapor increased and that the model could expect over-all mass transfer coefficient within 30 [%] difference to experimental data. It was also cleared that mass transfer in packed-type rectifier was two to five times more enhanced than that in plate-type rectifier.

  11. Polycrystalline silicon availability for photovoltaic and semiconductor industries

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  12. Gas-phase processing of the silicon surface toward controlled coverage with selected species

    Microsoft Academic Search

    James Andrew Staffa

    1998-01-01

    As the level of contamination introduced to the surface is reduced through the use of cleaner chemicals and processes, the emphasis of cleaning is shifting from one of removing incidental contaminants to that of controlling the condition of the surface inherently produced by the preceding process and bridging the condition of the surface left by the preceding process steps with

  13. 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

    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

    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.

  14. Mitigating impact of rectified RF sheath potential on the ELMs

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Xu, Xueqiao; Xia, Tianyang

    2014-10-01

    Here we report on the BOUT++ simulation results for the mitigating impact of rectified RF sheath potential on the peeling-ballooning modes. The limiter and the RF wave antenna are placed at the outer middle plane in the scrape-off-layer (SOL) in shift-circle geometry. The external shear flow is induced by the limiter and the RF wave. Besides this, the sheath boundary conditions are imposed on the perturbed potential and parallel current. From the three-field simulations, it is found that the energy loss is suppressed by the external shear flow in the nonlinear phase. The external shear flow due to the RF wave leads to a broad turbulence spectrum. The wider spectrum leads to a weaker turbulence transport and results in a smaller energy loss. The perturbed electric potential and the parallel current near the sheath region are also suppressed locally due to the sheath boundary condition. Based on this work, this effect of limiter will also be applied in six-field which includes more physics effects. The effect of sheath boundary conditions on the thermal conductivities and heat flux will be studied. This work was performed for USDOE by LLNL under DE-AC52-07NA27344, LLNL LDRD project 12-ERD-022 and the China Natural Science Foundation under Contract No. 10721505. LLNL-ABS-657008.

  15. Permeation and Gating of an Inwardly Rectifying Potassium Channel

    PubMed Central

    Choe, Han; Sackin, Henry; Palmer, Lawrence G.

    1998-01-01

    Permeation, gating, and their interrelationship in an inwardly rectifying potassium (K+) channel, ROMK2, were studied using heterologous expression in Xenopus oocytes. Patch-clamp recordings of single channels were obtained in the cell-attached mode. The gating kinetics of ROMK2 were well described by a model having one open and two closed states. One closed state was short lived (?1 ms) and the other was longer lived (?40 ms) and less frequent (?1%). The long closed state was abolished by EDTA, suggesting that it was due to block by divalent cations. These closures exhibit a biphasic voltage dependence, implying that the divalent blockers can permeate the channel. The short closures had a similar biphasic voltage dependence, suggesting that they could be due to block by monovalent, permeating cations. The rate of entering the short closed state varied with the K+ concentration and was proportional to current amplitude, suggesting that permeating K+ ions may be related to the short closures. To explain the results, we propose a variable intrapore energy well model in which a shallow well may change into a deep one, resulting in a normally permeant K+ ion becoming a blocker of its own channel. PMID:9758862

  16. Rectified Asteroid Albedos and Diameters from IRAS and MSX

    E-print Network

    Ryan, Erin Lee

    2010-01-01

    Rectified diameters and albedo estimates of 1517 main belt asteroid selected from the IRAS and MSX asteroid photometry catalogues are derived from updated infrared thermal models, the Standard Thermal Model (STM) and the Near Earth Asteroid Thermal Model (NEATM), and Monte Carlo simulations, using new Minor Planet Center (MPC) compilations of absolute magnitudes (H-values) constrained by occultation and radar derived parameters. The NEATM approach produces a more robust estimate of albedos and diameters, yielding albedos of $p_{v}$(NEATM mean)$=0.081 \\pm 0.064$. The asteroid beaming parameter ($\\eta$) for the selected asteroids has a mean value of $1.07 \\pm 0.27$, and the smooth distribution of $\\eta$ suggests that this parameter is independent of asteroid properties such as composition. No trends in $\\eta$ due to size-dependent rotation rates are evident. Comparison of derived $\\eta$'s as a function of taxonomic type indicates the beaming parameter values for S-type and C-type asteroids are identical within ...

  17. A High-Throughput Electrophysiology Assay Identifies Inhibitors of the Inwardly Rectifying Potassium Channel Kir7.1.

    PubMed

    Wright, Paul D; Kanumilli, Srinivasan; Tickle, David; Cartland, Jamie; Bouloc, Nathalie; Dale, Timothy; Tresize, Derek J; McCloskey, Conor; McCavera, Samantha; Blanks, Andrew M; Kettleborough, Catherine; Jerman, Jeffrey C

    2015-07-01

    Kir7.1 is an inwardly rectifying potassium channel that has been implicated in controlling the resting membrane potential of the myometrium. Abnormal uterine activity in pregnancy plays an important role in postpartum hemorrhage, and novel therapies for this condition may lie in manipulation of membrane potential. This work presents an assay development and screening strategy for identifying novel inhibitors of Kir7.1. A cell-based automated patch-clamp electrophysiology assay was developed using the IonWorks Quattro (Molecular Devices, Sunnyvale, CA) system, and the iterative optimization is described. In total, 7087 compounds were tested, with a hit rate (>40% inhibition) of 3.09%. During screening, average Z' values of 0.63 ± 0.09 were observed. After chemistry triage, lead compounds were resynthesized and activity confirmed by IC50 determinations. The most potent compound identified (MRT00200769) gave rise to an IC50 of 1.3 µM at Kir7.1. Compounds were assessed for selectivity using the inwardly rectifying potassium channel Kir1.1 (ROMK) and hERG (human Ether-à-go-go Related Gene). Pharmacological characterization of known Kir7.1 inhibitors was also carried out and analogues of VU590 tested to assess selectivity at Kir7.1. PMID:25656238

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

    PubMed

    Zeplin, Philip H

    2012-03-01

    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

  19. Automotive Power Generation and Control

    E-print Network

    Caliskan, Vahe

    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 ...

  20. The role of the epidermis in the control of scarring: evidence for mechanism of action for silicone gel.

    PubMed

    Tandara, Andrea A; Mustoe, Thomas A

    2008-10-01

    Hypertrophic scars can be reduced by the application of silicone dressing; however, the detailed mechanism of silicone action is still unknown. It is known that silicone gel sheets cause a hydration of the epidermal layer of the skin. An in vitro co-culture experiment has shown that hydration of keratinocytes has a suppressive effect on the metabolism of the underlying fibroblasts resulting in reduced collagen deposition. We tested the hypothesis that silicone sheeting in vivo has a beneficial effect on scarring by reducing keratinocyte stimulation, with a resulting decrease in dermal thickness, hence scar hypertrophy. Silicone adhesive gel sheets were applied to scars in our rabbit ear model of hypertrophic scarring 14 days postwounding for a total of 16 days. Scarring was measured in this model by the scar elevation index (SEI), a ratio of the area of newly formed dermis to the area of the dermis of unwounded skin, and the epidermal thickness index (ETI), a ratio of the averaged epidermal height of the scar to the epidermal thickness of normal epidermis. Specific staining [anti-PCNA (proliferating cell nuclear antigen) and Masson trichrome] was performed to reveal differences in scar morphology. SEIs were significantly reduced after silicone gel sheet application versus untreated scars corresponding to a 70% reduction in scar hypertrophy. Total occlusion reduced scar hypertrophy by 80% compared to semi-occlusion. ETIs of untreated scars were increased by more than 100% compared to uninjured skin. Silicone gel treatment significantly reduced epidermal thickness by more than 30%. Our findings demonstrate that 2 weeks of silicone gel application at a very early onset of scarring reduces dermal and epidermal thickness which appears to be due to a reduction in keratinocyte stimulation. Oxygen can be ruled out as a mechanism of action of silicone occlusive treatment. Hydration of the keratinocytes seems to be the key stimulus. PMID:18653391

  1. A high switching frequency IGBT PWM rectifier/inverter system for ac motor drives operating from single phase supply

    NASA Astrophysics Data System (ADS)

    Thiyagarajah, K.; Ranganathan, V. T.; Ramakrishna Iyengar, B. S.

    1991-10-01

    A pulse-width-modulated (PWM) rectifier/inverter system using insulated-gate-bipolar-transistors (IGBTs), capable of switching at 20 kHz is reported. The base drive circuit for the IGBT, incorporating short-circuit protection, is presented. The inverter uses an Undeland snubber together with a simple energy recovery circuit, which ensures reliable and efficient operation even for 20 kHz switching. The front end for the system is a regenerative single phase full-bridge IGBT inverter along with an ac reactor. Steady-state design considerations are explained, and control techniques for unity power factor operation and fast current control of the front end converter, in a rotating as well as a stationary reference frame, are discussed and compared. Results from computer simulations and experimental results for a 1.5-kW prototype system are presented.

  2. Characteristics of degenerately doped silicon for spectral control in thermophotovoltaic systems

    SciTech Connect

    Ehsani, H.; Bhat, I.; Borrego, J.; Gutmann, R. [Rensselaer Polytechnic Inst., Troy, NY (United States); Brown, E.; Dzeindziel, R.; Freeman, M.; Choudhury, N. [Lockheed-Martin, Schenectady, NY (United States)

    1995-07-01

    Heavily doped Si was investigated for use as spectral control filter in thermal photovoltaic (TPV) system. These filters should reflect radiation at 4 {micro}m and above and transmit radiation at 2 {micro}m and below. Two approaches have been used for introducing impurities into Si to achieve high doping concentration. One was the diffusion technique, using spin-on dopants. The plasma wavelength ({lambda}{sub p}) of these filters could be adjusted by controlling the diffusion conditions. The minimum plasma wavelength achieved was 4.8 {micro}m. In addition, a significant amount of absorption was observed for the wavelength 2 {micro}m and below. The second approach was doping by ion implantation followed by thermal annealing with a capped layer of doped glass. Implantation with high dosage of B and As followed by high temperature annealing (> 1,000 C) resulted in a plasma wavelength that could be controlled between 3.5 and 6 {micro}m. The high temperature annealing (> 1,000 C) that was necessary to activate the dopant atoms and to heal the implantation damage, also caused significant absorption at 2 {micro}m. For phosphorus implanted Si, a moderate temperature (800--900 C) was sufficient to activate most of the phosphorus and to heal the implantation damage. The position of the plasma turn-on wavelength for an implantation dose of 2 {times} 10{sup 16} cm{sup {minus}2} of P was at 2.9 {micro}m. The absorption at 2 {micro}m was less than 20% and the reflection at 5 {micro}m was about 70%.

  3. An 18.2%-efficient black-silicon solar cell achieved through control of carrier recombination in nanostructures.

    PubMed

    Oh, Jihun; Yuan, Hao-Chih; Branz, Howard M

    2012-11-01

    Silicon nanowire and nanopore arrays promise to reduce manufacturing costs and increase the power conversion efficiency of photovoltaic devices. So far, however, photovoltaic cells based on nanostructured silicon exhibit lower power conversion efficiencies than conventional cells due to the enhanced photocarrier recombination associated with the nanostructures. Here, we identify and separately measure surface recombination and Auger recombination in wafer-based nanostructured silicon solar cells. By identifying the regimes of junction doping concentration in which each mechanism dominates, we were able to design and fabricate an independently confirmed 18.2%-efficient nanostructured 'black-silicon' cell that does not need the antireflection coating layer(s) normally required to reach a comparable performance level. Our results suggest design rules for efficient high-surface-area solar cells with nano- and microstructured semiconductor absorbers. PMID:23023643

  4. An 18.2%-efficient black-silicon solar cell achieved through control of carrier recombination in nanostructures

    NASA Astrophysics Data System (ADS)

    Oh, Jihun; Yuan, Hao-Chih; Branz, Howard M.

    2012-12-01

    Silicon nanowire and nanopore arrays promise to reduce manufacturing costs and increase the power conversion efficiency of photovoltaic devices. So far, however, photovoltaic cells based on nanostructured silicon exhibit lower power conversion efficiencies than conventional cells due to the enhanced photocarrier recombination associated with the nanostructures. Here, we identify and separately measure surface recombination and Auger recombination in wafer-based nanostructured silicon solar cells. By identifying the regimes of junction doping concentration in which each mechanism dominates, we were able to design and fabricate an independently confirmed 18.2%-efficient nanostructured `black-silicon' cell that does not need the antireflection coating layer(s) normally required to reach a comparable performance level. Our results suggest design rules for efficient high-surface-area solar cells with nano- and microstructured semiconductor absorbers.

  5. Controllable shrinking and shaping of silicon nitride nanopores under electron irradiation

    SciTech Connect

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

    2007-04-16

    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.

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

    SciTech Connect

    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

    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.

  7. Crystal Structure of the Eukaryotic Strong Inward-Rectifier K+ Channel Kir2.2 at 3.1 Å Resolution

    PubMed Central

    Tao, Xiao; Avalos, Jose L.; Chen, Jiayun; MacKinnon, Roderick

    2010-01-01

    Inward-rectifier potassium (K+) channels conduct K+ ions most efficiently in one direction, into the cell. Kir2 channels control the resting membrane voltage in many electrically excitable cells and heritable mutations cause periodic paralysis and cardiac arrhythmia. We present the crystal structure of Kir2.2 from chicken, which, excluding the unstructured amino and carboxyl termini, is 90% identical to human Kir2.2. Crystals containing rubidium (Rb+), strontium (Sr2+), and europium (Eu3+) reveal binding sites along the ion conduction pathway that are both conductive and inhibitory. The sites correlate with extensive electrophysiological data and provide a structural basis for understanding rectification. The channel’s extracellular surface, with large structured turrets and an unusual selectivity filter entryway, might explain the relative insensitivity of eukaryotic inward rectifiers to toxins. These same surface features also suggest a possible approach to the development of inhibitory agents specific to each member of the inward-rectifier K+ channel family. PMID:20019282

  8. High-performance AlGaN /GaN lateral field-effect rectifiers compatible with high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Chen, Wanjun; Wong, King-Yuen; Huang, Wei; Chen, Kevin J.

    2008-06-01

    A high electron mobility transistor (HEMT)-compatible power lateral field-effect rectifier (L-FER) with low turn-on voltage is demonstrated using the same fabrication process as that for normally off AlGaN /GaN HEMT, providing a low-cost solution for GaN power integrated circuits. The power rectifier features a Schottky-gate-controlled two-dimensional electron gas channel between the cathode and anode. By tying up the Schottky gate and anode together, the forward turn-on voltage of the rectifier is determined by the threshold voltage of the channel instead of the Schottky barrier. The L-FER with a drift length of 10?m features a forward turn-on voltage of 0.63V at a current density of 100A/cm2. This device also exhibits a reverse breakdown voltage (BV) of 390V at a current level of 1mA/mm and a specific on resistance (RON,sp) of 1.4m?cm2, yielding a figure of merit (BV2/RON,sp) of 108MW/cm2. The excellent device performance, coupled with the lateral device structure and process compatibility with AlGaN /GaN HEMT, make the proposed L-FER a promising candidate for GaN power integrated circuits.

  9. The ratio of germanium to silicon in plant phytoliths: quantification of biological discrimination under controlled experimental conditions

    Microsoft Academic Search

    Steve W. Blecker; Stagg L. King; Louis A. Derry; Oliver A. Chadwick; James A. Ippolito; Eugene F. Kelly

    2007-01-01

    Slight differences in the chemical behavior of germanium (Ge) and silicon (Si) during soil weathering enable Ge\\/Si ratios\\u000a to be used as a tracer of Si pathways. Mineral weathering and biogenic silicon cycling are the primary modifiers of Ge\\/Si\\u000a ratios, but knowledge of the biogenic cycling component is based on relatively few studies. We conducted two sets of greenhouse\\u000a experiments

  10. D0 Silicon Upgrade: Control Dewar Steady State Thermodynamic Operating Goals

    SciTech Connect

    Rucincki, Russ; /Fermilab

    1995-10-20

    This engineering note documents the thermodynamic operating parameter goals for the steady state operation of the control dewar/solenoid system. Specifically, how the control dewar pressure control valve, PV-3062-H and the magnet flow control valve EVMF are operated to give the lowest possible temperature fluid at the solenoid magnet. The goals are: (1) For PV-3062-H - The process variable is the helium reservoir pressure, minimize the reservoir pressure, provide only enough pressure plus a little margin to ensure leads flow; and (2) For EVMF - The process variable is firstly a manual setpoint of flowrate as read by the flow venturi, FE3253-H, and secondly the reservoir liquid level, minimize the pressure drop thru the solenoid cooling tubes, provide at least enough flow to maintain reservoir level and stable operation of the magnet. The thermodynamic states for the fluid thru the system are shown on the Pressure versus Temperature graph. Lines of constant enthalpy are also shown. State A is shown as two phase liquid entering the inlet of the subcooler. The subcooler subcools the fluid to State B. State B to State C is caused by the pressure drop across EVMF. State C to D is the estimated pressure drop from the outlet of EVMF thru the solenoid cooling tubes and back up to the helium reservoir inlet. To give the coolest fluid in the cooling tubes, the two phase fluid in the reservoir should be at the lowest pressure (and thus temperature). This lowest pressure is limited by the required pressure for leads flow and if this does not dominate, the low pressure side pressure drop thru the refrigerator and suction pressure set point. My guess is the lead flow requirement will dominate. I suggest putting the PV-3062-H set point such that the lead flow control valves operate at about 80% open. The second parameter that will give the coolest fluid in the cooling tubes is a minimized pressure drop thru the cooling tubes. This can be accomplished by providing a minimized flowrate, sufficient only to ensure that the reservoir level is full and some liquid fraction leaves the helium outlet tubing. D-Zero Engineering note, EN-338, 'LHe Flow Regime/Pressure Drop for DO Solenoid at Steady State Conditions' shows that even though the gas fraction increases at lower flowrates, the pressure drop decreases. This goal is ideal, and assumes good cooling at the magnet. Real effects such hot spots or quench experience in the magnet may necessitate a higher flowrate. The current design flow rate from Toshiba is somewhere around 2.5 gls which is very low. Experience with the accuracy of the venturi flowmeter, coil characteristics etc. and some conservativeness will help determine the optimum flowrate. I would venture a guess that it would be a minimum of 5 g/s. The philosophy that I have been taking with transfer line and valve sizing is such that our refrigerator system will have the ability to supply up to at least 20 g/s if required and necessary. Preferably we will be around 5 g/s.

  11. Periodic silicon nanocone arrays with controllable dimensions prepared by two-step etching using nanosphere lithography and NH4OH/H2O2 solution

    NASA Astrophysics Data System (ADS)

    Yang, Mingfei; Yu, HongYu; Sun, Xiaowei; Li, Junshuai; Li, Xiaocheng; Ke, Lin; Hu, Junhui; Wang, Fei; Jiao, Zhihui

    2011-01-01

    An electroless chemical etching technique using polystyrene nanospheres as a self-assembled mask is developed to fabricate size-controllable, periodic silicon nanopillars (NPs) and subsequent nanocone (NC) arrays. The Si NCs are obtained based on the NPs structure using cost-effective ammonia-related etching chemistry. The diameter, height, and periodicity of the NCs can be systematically controlled. Optical measurement shows a good improvement in the reduction of reflectance properties with Si NCs structures. This method is potentially beneficial to many device applications including super-capacitors, batteries, solar cells, etc.

  12. BOREAS TE-18, 60-m, Radiometrically Rectified Landsat TM Imagery

    NASA Technical Reports Server (NTRS)

    Hall, Forrest G. (Editor); Knapp, David

    2000-01-01

    The BOREAS TE-18 team used a radiometric rectification process to produce standardized DN values for a series of Landsat TM images of the BOREAS SSA and NSA in order to compare images that were collected under different atmospheric conditions. The images for each study area were referenced to an image that had very clear atmospheric qualities. The reference image for the SSA was collected on 02-Sep-1994, while the reference image for the NSA was collected on 2 1 Jun-1995. The 23 rectified images cover the period of 07-Jul-1985 to 18-Sep-1994 in the SSA and 22-Jun-1984 to 09-Jun-1994 in the NSA. Each of the reference scenes had coincident atmospheric optical thickness measurements made by RSS-11. The radiometric rectification process is described in more detail by Hall et al. (1991). The original Landsat TM data were received from CCRS for use in the BOREAS project. Due to the nature of the radiometric rectification process and copyright issues, the full-resolution (30-m) images may not be publicly distributed. However, this spatially degraded 60-m resolution version of the images may be openly distributed and is available on the BOREAS CD-ROM series. After the radiometric rectification processing, the original data were degraded to a 60-m pixel size from the original 30-m pixel size by averaging the data over a 2- by 2-pixel window. The data are stored in binary image-format files. The data files are available on a CD-ROM (see document number 20010000884), or from the Oak Ridge National Laboratory (ORNL) Distributed Activity Archive Center (DAAC).

  13. Silicon Control of Strontium and Cesium Partitioning in Hydroxide-Weathered Sediments

    SciTech Connect

    Chorover, Jon; Choi, Sunkyung; Rotenberg, P.; Serne, R. Jeffrey; Rivera, Nelson; Strepka, Caleb R.; Thompson, Aaron; Mueller, Karl T.; O'Day, Peggy A.

    2008-04-15

    Cation partitioning in an aqueous soil suspension depends on the coupling of reaction time, sorbate amount and mineral weathering reactions. These factors were varied in sediment suspension experiments to identify geochemical processes that affect migration of Sr2+ and Cs+ introduced to the subsurface by caustic high level radioactive waste (HLRW). Three glacio-fluvial and lacustrine sediments from the Hanford Site were subjected to hyperalkaline (pH > 13), Na–Al–NO3–OH solution conditions within a gradient field of (i) sorptive concentration (10-5–10-3 M) and (ii) reaction time (0–365 d). Strontium uptake (qSr) exceeded that of cesium at nearly all reaction times. Sorbent affinity for both Cs+ and Sr2+ increased with clay plus silt content at early times, but a prolonged slow uptake process was observed over the course of sediment weathering that erased the texture effect for Sr2+; all sediments showed similar mass normalized uptake after several months of reaction time. Strontium became progressively recalcitrant to desorption after 92 d, with accumulation and aging of neoformed aluminosilicates. Formation of Cs+ and Sr2+-containing cancrinite and sodalite was observed after 183 d by SEM and synchrotron u-XRF and u-XRD. EXAFS data showed ncorporation of Sr2+ into both feldspathoid and SrCO3(s) coordination environments after one year. Adsorption was predominant at early times and low sorbate amount, whereas recipitation, controlled largely by sediment Si release, became increasingly important at longer times and higher sorbate amount. Kinetics of contaminant desorption at pH 8 from one year-weathered sediments showed significant dependence on background cation (Ca2+ versus K+) composition. Results of this study indicate that co-precipitation and ion exchange in neoformed aluminosilicates may be an important mechanism controlling Sr2+ and Cs+ mobility in siliceous sediments impacted by hyperalkaline HLRW.

  14. High-power 4H-SiC JBS rectifiers

    Microsoft Academic Search

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

    2002-01-01

    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

  15. Growth of carbon nanotubes and semiconductor nanowires on silicon by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lee, Ki-Hong

    Carbon nanotubes (CNTs) are a promising material for nano-electronic devices because of their electrical properties and very small diameter. However, controlling their electronic properties depending on chirality and tube diameter of the CNTs and growth direction of the CNTs has been a challenge for realizing nanotube-based electronic devices. Until now, the growth mechanism of CNTs was not fully understood and controlling the growth of CNTs completely is still a major challenge. Understanding of the growth mechanism of CNTs is an essential in order to achieve controllability in both growth direction and electrical properties of nanotubes by chemical vapor deposition (CVD). There are many variables, however, to consider in this process, including the type of gases, catalyst metals, and supporting substrates. Supporting substrates of the catalyst metals are also an important factor in the growth of carbon nanotube. It is known that interaction between catalyst particle and support is required for catalytic activity. In particular, oxygen-containing materials are known as a suitable support for this purpose. Our study is focused on the growth mechanism of CNTs on silicon oxide by chemical vapor deposition (CVD). In particular, the chemical interaction between the vapor phase and the supporting oxide is investigated relating to the growth mechanism of CNTs. Methane (CH4) and hydrogen (H2) are used as reaction gases and nickel is used as a catalyst. CO is generated by chemical interaction between the supporting oxide and the process gases; thereby complicates the composition of the gas components in CVD process. In order to modulate CO vapor concentration in the system, metal oxide powders, such as titanium oxide (TiO2), silicon oxide (SiO2) and silicon oxide/iron nitrate mixture are adopted based on the thermodynamic calculation of CO vapor pressure of the each oxide in the CH4-H2 system. Nanotubes can be used individually or as an ensemble to build a functional device prototype. Ensembles of nanotubes have been used for field emission based flat panel display. Individual nanotubes have been used for field emission sources and as tips for scanning probes. Nanotubes also have significant potential as the central elements of nano-electronic devices including field effect transistors (FETs), single-electron transistors, and rectifying diodes. In an effort to find a way to align carbon nanotubes on silicon substrate, the growth orientation of carbon nanotube is investigated on single crystal iron nano particles on silicon wafer. The iron nano particles are adhered to the substrate by magnetic field from dispersion. Our study suggests the possibility of controlling the growth orientation of the CNTs. Furthermore, novel evidence is given for the growth mechanism of the CNTs by CVD.

  16. Impedance characterization of a six-phase synchronous generator-rectifier system using average-value model

    Microsoft Academic Search

    Juri Jatskevich; Tarek Aboul-Seoud

    2004-01-01

    A parametric approach for developing a dynamic average-value model of a machine-rectifier system is presented. The method initially requires a detailed switched model from which the rectifier\\/DC-link dynamics are captured using numerical averaging. The method is applied to a 240 Hz 6-phase synchronous generator-rectifier system. This system exhibits several distinct modes of operation. The output impedance is extracted using the

  17. Simple evaporation controller for thin-film deposition from a resistively heated boat

    NASA Technical Reports Server (NTRS)

    Scofield, John H.; Bajuk, Lou; Mohler, William

    1990-01-01

    A simple, inexpensive circuit is described for switching the current through a resistively heated evaporation boat during thin-film deposition. The circuit uses a silicon-controlled rectifier (SCR) to switch the 0-15-A current in the primary of a 2-kV A step-down transformer that supplies the 0-200-A current to an evaporation boat. The circuit is controlled by a 0-10 V-dc signal similar to that furnished by an Inficon XTC deposition-rate controller. This circuit may be assembled from a handful of parts for a cost of about $400, nearly one-tenth the cost of similar commercial units. Minimum construction is required, since the circuit is built around an off-the-shelf, self-contained SCR unit.

  18. D0 Silicon Upgrade: Control Dewar Venturi Calibration Explanation for Toshiba

    SciTech Connect

    Kuwazaki, Andrew; /Fermilab

    1997-01-24

    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.

  19. Synthesis and structural control of silicon and silicide nanowires/microrods using metal chloride sources

    NASA Astrophysics Data System (ADS)

    Tatsuoka, Hirokazu; Suzuki, Hiroaki; Suzuki, Takanori; Li, Wen; Hu, Junhua; Meng, Xiang; Meng, Erchao

    2015-07-01

    Si and silicide nanowires/microrods were synthesized using metal-chloride-based sources by the CVD technique. In the case of Si nanowire synthesis, the morphological structures of the products depended on the distance from the source material. The distance dependence of the morphological and structural properties of the nanostructures was investigated to systemically clarify the shape modification phenomena in Si nanowire synthesis. The modification of the cross-sectional shape of the Si nanowires/microrods was successfully demonstrated. The triangular nanowire has a sawtooth faceting structure on its sidewall. In addition, the synthesis of Mn-silicide phases over the entire range of the Mn–Si system was examined. The effect of adding an impurity to the source materials on the structural modifications of the resulting nanowires/microrods was also investigated. It is expected that the morphological and structural control of the nanowires/microrods will be improved by a simple thermal treatment using a metal chloride as the source material.

  20. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: SiC based Si/SiC heterojunction and its rectifying characteristics

    NASA Astrophysics Data System (ADS)

    Zhu, Feng; Chen, Zhi-Ming; Li, Lian-Bi; Zhao, Shun-Feng; Lin, Tao

    2009-11-01

    The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play the role of an light absorbing layer. This paper reports on Si films heteroepitaxially grown on the Si face of (0001) n-type 6H-SiC substrates and the use of B2H6 as a dopant for p-Si grown at temperatures in a range of 700-950 °C. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) tests have demonstrated that the samples prepared at the temperatures ranged from 850 °C to 900 °C are characterized as monocrystalline silicon. The rocking XRD curves show a well symmetry with FWHM of 0.4339° Omega. Twin crystals and stacking faults observed in the epitaxial layers might be responsible for widening of the rocking curves. Dependence of the crystal structure and surface topography on growth temperature is discussed based on the experimental results. The energy band structure and rectifying characteristics of the Si/SiC heterojunctions are also preliminarily tested.

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

    NASA Astrophysics Data System (ADS)

    Shul, Randy

    2003-10-01

    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.

  2. Optical properties of silicon inverse opals

    Microsoft Academic Search

    Hong Wei

    2007-01-01

    Silicon inverse opals are artificial structures in which nearly monodisperse, close-packed air bubbles are embedded in a silicon matrix. If properly tailored, this structure can exhibit a photonic band gap (PBG) in the near infrared spectral region. The PBG can block light propagation in any direction, allowing the control of light flow in the material. Silicon inverse opals can be

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

    PubMed Central

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

    2011-01-01

    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

  4. Mechanism of Rectification in Inward-rectifier K+ Channels

    PubMed Central

    Guo, Donglin; Ramu, Yajamana; Klem, Angela M.; Lu, Zhe

    2003-01-01

    Rectification in inward-rectifier K+ channels is caused by the binding of intracellular cations to their inner pore. The extreme sharpness of this rectification reflects strong voltage dependence (apparent valence is ?5) of channel block by long polyamines. To understand the mechanism by which polyamines cause rectification, we examined IRK1 (Kir2.1) block by a series of bis-alkyl-amines (bis-amines) and mono-alkyl-amines (mono-amines) of varying length. The apparent affinity of channel block by both types of alkylamines increases with chain length. Mutation D172N in the second transmembrane segment reduces the channel's affinity significantly for long bis-amines, but only slightly for short ones (or for mono-amines of any length), whereas a double COOH-terminal mutation (E224G and E299S) moderately reduces the affinity for all bis-amines. The apparent valence of channel block increases from ?2 for short amines to saturate at ?5 for long bis-amines or at ?4 for long mono-amines. On the basis of these and other observations, we propose that to block the channel pore one amine group in all alkylamines tested binds near the same internal locus formed by the COOH terminus, while the other amine group of bis-amines, or the alkyl tail of mono-amines, “crawls” toward residue D172 and “pushes” up to 4 or 5 K+ ions outwardly across the narrow K+ selectivity filter. The strong voltage dependence of channel block therefore reflects the movement of charges carried across the transmembrane electrical field primarily by K+ ions, not by the amine molecule itself, as K+ ions and the amine blocker displace each other during block and unblock of the pore. This simple displacement model readily accounts for the classical observation that, at a given concentration of intracellular K+, rectification is apparently related to the difference between the membrane potential and the equilibrium potential for K+ ions rather than to the membrane potential itself. PMID:12642596

  5. Ion selectivity and current saturation in inward-rectifier K+ channels

    PubMed Central

    Yang, Lei; Edvinsson, Johan; Sackin, Henry

    2012-01-01

    We investigated the features of the inward-rectifier K channel Kir1.1 (ROMK) that underlie the saturation of currents through these channels as a function of permeant ion concentration. We compared values of maximal currents and apparent Km for three permeant ions: K+, Rb+, and NH4+. Compared with K+ (imax = 4.6 pA and Km = 10 mM at ?100 mV), Rb+ had a lower permeability, a lower imax (1.8 pA), and a higher Km (26 mM). For NH4+, the permeability was reduced more with smaller changes in imax (3.7 pA) and Km (16 mM). We assessed the role of a site near the outer mouth of channel in the saturation process. This site could be occupied by either permeant ions or low-affinity blocking ions such as Na+, Li+, Mg2+, and Ca2+ with similar voltage dependence (apparent valence, 0.15–0.20). It prefers Mg2+ over Ca2+ and has a monovalent cation selectivity, based on the ability to displace Mg2+, of K+ > Li+ ? Na+ > Rb+ ? NH4+. Conversely, in the presence of Mg2+, the Km for K+ conductance was substantially increased. The ability of Mg2+ to block the channels was reduced when four negatively charged amino acids in the extracellular domain of the channel were mutated to neutral residues. The apparent Km for K+ conduction was unchanged by these mutations under control conditions but became sensitive to the presence of external negative charges when residual divalent cations were chelated with EDTA. The results suggest that a binding site in the outer mouth of the pore controls current saturation. Permeability is more affected by interactions with other sites within the selectivity filter. Most features of permeation (and block) could be simulated by a five-state kinetic model of ion movement through the channel. PMID:22291146

  6. Theoretical study on the rectifying performance of organoimido derivatives of hexamolybdates.

    PubMed

    Wen, Shizheng; Yang, Guochun; Yan, Likai; Li, Haibin; Su, Zhongmin

    2013-02-25

    We design a new type of molecular diode, based on the organoimido derivatives of hexamolybdates, by exploring the rectifying performances using density functional theory combined with the non-equilibrium Green's function. Asymmetric current-voltage characteristics were obtained for the models with an unexpected large rectification ratio. The rectifying behavior can be understood by the asymmetrical shift of the transmission peak observed under different polarities. It is interesting to find that the preferred electron-transport direction in our studied system is different from that of the organic D-bridge-A system. The results show that the studied organic-inorganic hybrid systems have an intrinsically robust rectifying ratio, which should be taken into consideration in the design of the molecular diodes. PMID:23303530

  7. Rectifying Single GaAsSb Nanowire Devices Based on Self-Induced Compositional Gradients.

    PubMed

    Huh, Junghwan; Yun, Hoyeol; Kim, Dong-Chul; Munshi, A Mazid; Dheeraj, Dasa L; Kauko, Hanne; van Helvoort, Antonius T J; Lee, SangWook; Fimland, Bjørn-Ove; Weman, Helge

    2015-06-10

    Device configurations that enable a unidirectional propagation of carriers in a semiconductor are fundamental components for electronic and optoelectronic applications. To realize such devices, however, it is generally required to have complex processes to make p-n or Schottky junctions. Here we report on a unidirectional propagation effect due to a self-induced compositional variation in GaAsSb nanowires (NWs). The individual GaAsSb NWs exhibit a highly reproducible rectifying behavior, where the rectifying direction is determined by the NW growth direction. Combining the results from confocal micro-Raman spectroscopy, electron microscopy, and electrical measurements, the origin of the rectifying behavior is found to be associated with a self-induced variation of the Sb and the carrier concentrations in the NW. To demonstrate the usefulness of these GaAsSb NWs for device applications, NW-based photodetectors and logic circuits have been made. PMID:25941743

  8. Rectifying properties of magnetite-based Schottky diode and the effects of magnetic field

    NASA Astrophysics Data System (ADS)

    Chen, Y. Z.; Sun, J. R.; Xie, Y. W.; Wang, D. J.; Lu, W. M.; Liang, S.; Shen, B. G.

    2007-04-01

    Rectifying properties, with and without magnetic field, of a high quality Fe3O4/SrTiO3:Nb Schottky diode have been experimentally studied. The junction exhibits an excellent rectifying behavior both below and above the Verwey temperature (TV) of Fe3O4. Magnetic field has a weak but visible effect on the transport process of the junction, producing a negative magnetoresistance for T TV. Based on an analysis of the current-voltage characteristics, the spin polarization of Fe3O4 has been deduced. It is a strong function of temperature, varying between -78% and 18%.

  9. A novel readout chip for silicon strip detectors with analog pipeline and digitally controlled analog signal processing

    Microsoft Academic Search

    R. Horisberger; D. Pitzl

    1993-01-01

    A readout chip for silicon strip detectors with analog event pipeline has been fabricated (SACMOS 2 mum technology) and tested. The chip has been designed to operate at the HERA ep collider at a bunch crossing rate of 10.4 MHz. Each channel has a layout width of 44 mum and consists of a fast, low noise, low power preamplifier followed

  10. Impact of the Physical Layout of High-Current Rectifiers on Current Division and Magnetic Field Using PEEC Method

    Microsoft Academic Search

    Jean-Luc Schanen; Jean-Michel Guichon; James Roudet; Cyril Domenech; Luc Meysenc

    2010-01-01

    This paper addresses some problems linked to the physical layout of high-current rectifiers: paralleling components, magnetic field close to the rectifier, and also the validation of the physical layout at reduced current. Even if the impact of cabling stray inductance is well known, some new tools and methodology are available today to design quicker and safer physical layout of such

  11. Design and Realization of Autonomous Power CMOS Single Phase Inverter and Rectifier for Low Power Conditioning Applications

    E-print Network

    Paris-Sud XI, Université de

    Design and Realization of Autonomous Power CMOS Single Phase Inverter and Rectifier for Low Power operate as an inverter or as a rectifier in a wide range of power flows and input voltages. Three of the inverter reaches up to 92% as a function of input voltage with these conditions. The second experimental

  12. Silicon Photonics

    Microsoft Academic Search

    Bahram Jalali; Sasan Fathpour

    2006-01-01

    After dominating the electronics industry for decades, silicon is on the verge of becoming the material of choice for the photonics industry: the traditional stronghold of III-V semiconductors. Stimulated by a series of recent breakthroughs and propelled by increasing investments by governments and the private sector, silicon photonics is now the most active discipline within the field of integrated optics.

  13. Microrectenna: A Terahertz Antenna and Rectifier on a Chip

    NASA Technical Reports Server (NTRS)

    Siegel, Peter

    2007-01-01

    A microrectenna that would operate at a frequency of 2.5 THz has been designed and partially fabricated. The circuit is intended to be a prototype of an extremely compact device that could be used to convert radio-beamed power to DC to drive microdevices (see Figure 1). The microrectenna (see Figure 2) circuit consists of an antenna, a diode rectifier and a DC output port. The antenna consists of a twin slot array in a conducting ground plane (denoted the antenna ground plane) over an enclosed quarter-wavelength-thick resonant cavity (denoted the reflecting ground plane). The circuit also contains a planar high-frequency low-parasitic Schottky-barrier diode, a low-impedance microstrip transmission line, capacitors, and contact beam leads. The entire 3-D circuit is fabricated monolithically from a single GaAs wafer. The resonant cavity renders the slot radiation pattern unidirectional with a half-power beam width of about 65. A unique metal mesh on the rear of the wafer forms the backplate for the cavity but allows the GaAs to be wet etched from the rear surface of the twin slot antennas and ground plane. The beam leads protrude past the edge of the chip and are used both to mount the microrectenna and to make the DC electrical connection with external circuitry. The antenna ground plane and the components on top of it are formed on a 2- m thick GaAs membrane that is grown in the initial wafer MBE (molecular beam epitaxy) process. The side walls of the antenna cavity are not metal coated and, hence, would cause some loss of power; however, the relatively high permittivity (epsilon=13) of the GaAs keeps the cavity modes well confined, without the usual surface-wave losses associated with thick dielectric substrates. The Schottky-barrier diode has the usual submicron dimensions associated with THz operation and is formed in a mesa process above the antenna ground plane. The diode is connected at the midpoint of a microstrip transmission line, which is formed on 1- m-thick SiO (permittivity of 5) laid down on top of the GaAs membrane. The twin slots are fed in phase by this structure. To prevent radio-frequency (RF) leakage past the slot antennas, low-loss capacitors are integrated into the microstrip transmission line at the edges of the slots. The DC current- carrying lines extend from the outer edges of the capacitors, widen approaching the edges of the chip, and continue past the edges of the chip to become the beam leads used in tacking down the devices. The structure provides a self-contained RF to DC converter that works in the THz range.

  14. Silicon graphene Bragg gratings

    NASA Astrophysics Data System (ADS)

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-03-01

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented.

  15. Silicon graphene Bragg gratings.

    PubMed

    Capmany, José; Domenech, David; Muñoz, Pascual

    2014-03-10

    We propose the use of interleaved graphene sections on top of a silicon waveguide to implement tunable Bragg gratings. The filter central wavelength and bandwidth can be controlled changing the chemical potential of the graphene sections. Apodization techniques are also presented. PMID:24663869

  16. Conformational Changes Underlying Pore Dilation in the Cytoplasmic Domain of Mammalian Inward Rectifier K+ Channels

    PubMed Central

    Inanobe, Atsushi; Nakagawa, Atsushi; Kurachi, Yoshihisa

    2013-01-01

    The cytoplasmic domain of inward rectifier K+ (Kir) channels associates with cytoplasmic ligands and undergoes conformational change to control the gate present in its transmembrane domain. Ligand-operated activation appears to cause dilation of the pore at the cytoplasmic domain. However, it is still unclear how the cytoplasmic domain supports pore dilation and how alterations to this domain affect channel activity. In the present study, we focused on 2 spatially adjacent residues, i.e., Glu236 and Met313, of the G protein-gated Kir channel subunit Kir3.2. In the closed state, these pore-facing residues are present on adjacent ?D and ?H strands, respectively. We mutated both residues, expressed them with the m2-muscarinic receptor in Xenopus oocytes, and measured the acetylcholine-dependent K+ currents. The dose-response curves of the Glu236 mutants tended to be shifted to the right. In comparison, the slopes of the concentration-dependent curves were reduced and the single-channel properties were altered in the Met313 mutants. The introduction of arginine at position 236 conferred constitutive activity and caused a leftward shift in the conductance-voltage relationship. The crystal structure of the cytoplasmic domain of the mutant showed that the arginine contacts the main chains of the ?H and ?I strands of the adjacent subunit. Because the ?H strand forms a ? sheet with the ?I and ?D strands, the immobilization of the pore-forming ? sheet appears to confer unique properties to the mutant. These results suggest that the G protein association triggers pore dilation at the cytoplasmic domain in functional channels, and the pore-constituting structural elements contribute differently to these conformational changes. PMID:24244570

  17. Controlled morphology and optical properties of n-type porous silicon: effect of magnetic field and electrode-assisted LEF

    PubMed Central

    2014-01-01

    Fabrication of photoluminescent n-type porous silicon (nPS), using electrode-assisted lateral electric field accompanied with a perpendicular magnetic field, is reported. The results have been compared with the porous structures fabricated by means of conventional anodization and electrode-assisted lateral electric field without magnetic field. The lateral electric field (LEF) applied across the silicon substrate leads to the formation of structural gradient in terms of density, dimension, and depth of the etched pores. Apart from the pore shape tunability, the simultaneous application of LEF and magnetic field (MF) contributes to a reduction of the dimension of the pores and promotes relatively more defined pore tips as well as a decreased side-branching in the pore walls of the macroporous structure. Additionally, when using magnetic field-assisted etching, within a certain range of LEF, an enhancement of the photoluminescence (PL) response was obtained. PMID:25313298

  18. Effectiveness of different designs of 12- and 24-pulse rectifier transformers

    Microsoft Academic Search

    A. Sikora; B. Kulesz

    2008-01-01

    Investigation of effectiveness of different designs of rectifier transformers of tram traction substations has covered issues such as transformer weight, rated power and efficiency and traction line voltage quality. Mathematical models have been created and time and frequency domain analysis has been run as well as power, voltage and current calculations for steady-state conditions. It is pointed out that transformer

  19. Small Signal Modeling for Phase-shifted PWM Converters with A Current Doubler Rectifier

    Microsoft Academic Search

    Liyu Cao

    2007-01-01

    A simple modeling method is proposed for deriving a small signal model for DC-DC converters with current doubler rectifiers. In the proposed method, the circuit model of converters with current doublers is simplified by decomposing the converter circuit into two identical subcircuits, and the well-established averaged circuit models can be applied to each subcircuit. The proposed method is then applied

  20. RECTIFIABILITY OF SELF-CONTRACTED CURVES IN THE EUCLIDEAN SPACE AND APPLICATIONS

    E-print Network

    -contracted curves. This yields a straightforward proof for the convergence of the exact proximal algorithm, underRECTIFIABILITY OF SELF-CONTRACTED CURVES IN THE EUCLIDEAN SPACE AND APPLICATIONS A. DANIILIDIS, G. DAVID, E. DURAND-CARTAGENA, A. LEMENANT Abstract. It is hereby established that, in Euclidean spaces

  1. Theoretical and experimental study of 2.45 GHz rectifying antennas 

    E-print Network

    McSpadden, James Oliver

    1993-01-01

    is reviewed separately. The rectifying diode is the key component in the rectenna circuit and understanding its characteristics is vital. A method has been devised to experimentally characterize a packaged GaAs Schottky barrier diode by inserting it in a...

  2. Current status of self rectifying air turbines for wave energy conversion

    Microsoft Academic Search

    Toshiaki Setoguchi; Manabu Takao

    2006-01-01

    This paper reviews the present state of the art on self rectifying air turbines, which could be used for wave energy conversion. The overall performances of the turbines under irregular wave conditions, which typically occur in the sea, have been evaluated numerically and compared from the viewpoints of their starting and running characteristics. The types of turbine included in the

  3. ON RECTIFIED LINEAR UNITS FOR SPEECH PROCESSING M.D. Zeiler1

    E-print Network

    Hinton, Geoffrey E.

    hundred hours of speech data. Index Terms-- Rectified Linear units, Deep Learning, Neural Networks-wise un- supervised learning algorithm, called Restricted Boltzmann Machine (RBM) [2], as a way to provide to design better unsupervised algorithms [3, 4] and better optimization methods for training deep neural

  4. Fast delayed rectifier potassium current is required for circadian neural activity

    Microsoft Academic Search

    Jason N Itri; Stephan Michel; Mariska J Vansteensel; Johanna H Meijer; Christopher S Colwell

    2005-01-01

    In mammals, the precise circadian timing of many biological processes depends on the generation of oscillations in neural activity of pacemaker cells in the suprachiasmatic nucleus (SCN). The ionic mechanisms that underlie these rhythms are largely unknown. Using the mouse brain slice preparation, we show that the magnitude of fast delayed rectifier (FDR) potassium currents has a diurnal rhythm that

  5. Functional inferences from reconstructed evolutionary biology involving rectified databases an evolutionarily grounded approach

    E-print Network

    Liberles, David

    logic was known to be fallible [3]. At the root of its fallibility is the biological phenomenonFunctional inferences from reconstructed evolutionary biology involving rectified databases. Liberlesa , Sridhar Govindarajanb , Lukas Knechtb a Departments of Chemistry and Anatomy and Cell Biology

  6. Asymptotics for discrete weighted minimal Riesz energy problems on rectifiable sets

    Microsoft Academic Search

    S. V. Borodachov; D. P. Hardin; E. B. Saff

    2008-01-01

    Given a compact $d$-rectifiable set $A$ embedded in Euclidean space and a\\u000adistribution $\\\\rho(x)$ with respect to $d$-dimensional Hausdorff measure on\\u000a$A$, we address the following question: how can one generate optimal\\u000aconfigurations of $N$ points on $A$ that are \\

  7. High-Efficiency X-Band MMIC GaN Power Amplifiers Operating as Rectifiers

    E-print Network

    Popovic, Zoya

    High-Efficiency X-Band MMIC GaN Power Amplifiers Operating as Rectifiers Michael Litchfield, Scott. Two single-stage MMIC power amplifiers are char acterized under continuous wave conditions at 10.1 GHz two 10 x 100j.Lm power combined devices. The MMICs exhibit 67% and 56% power added efficiency at VDD

  8. Design of multistage rectifiers with low-cost impedance matching for passive RFID tags

    Microsoft Academic Search

    Ray Barnett; Steve Lazar; Jin Liu

    2006-01-01

    The paper presents analysis of the input impedance, as well as the input capacitance and output resistance of diode doublers and multistage rectifiers. Tradeoffs between device sizes and the number of rectification stages are presented with an emphasis on low cost impedance matching. As a result, it is possible to achieve higher efficiency in RF to DC conversion with low

  9. Physical Layout of High Current Rectifiers: Modern Methods for an Old Challenge

    E-print Network

    Paris-Sud XI, Université de

    Physical Layout of High Current Rectifiers: Modern Methods for an Old Challenge JL.Schanen1 , JM Grenoble France Abstract-- This paper address some problems linked to the physical layout of high current of the physical layout at reduced current. Even if the impact of cabling stray inductance is well known, some new

  10. Grain and grain-boundary control of the transfer characteristics of large-grain polycrystalline silicon thin-film transistors

    Microsoft Academic Search

    F. V Farmakis; J Brini; G Kamarinos; C. T Angelis; C. A Dimitriadis; M Miyasaka; T Ouisse

    2000-01-01

    Thin-film transistors (TFTs), fabricated on solid-phase-crystallized polycrystalline silicon (polysilicon) films subjected to laser annealing, were studied. For the resulting large-grain polysilicon TFTs, a model is proposed that takes into account two well-distinguished regions within the channel of the transistor: the intra-grain region and the grain boundaries. By using this model, we found that the extracted on-voltage is mainly grain-boundary dependent

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

    PubMed Central

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

    2014-01-01

    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 24–36 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

  12. Nonlinear silicon photonics

    Microsoft Academic Search

    J. Leuthold; C. Koos; W. Freude

    2010-01-01

    The nonlinearities in silicon are diverse. This Review covers the wealth of nonlinear effects in silicon and highlights the important applications and technological solutions in nonlinear silicon photonics.

  13. Direct observation of dangling bond motion in disordered silicon N. H. Nickel

    E-print Network

    Schiff, Eric A.

    -center resonance in polycrystalline silicon. Distinct temperature dependences were found in as- prepared and hydrogen-passivated polycrystalline silicon. This observation invalidates the identification largely control the electronic properties of disor- dered silicons--amorphous, polycrystalline

  14. Silicone materials for LED packaging

    NASA Astrophysics Data System (ADS)

    Bahadur, Maneesh; Norris, Ann W.; Zarisfi, Afrooz; Alger, James S.; Windiate, Christopher C.

    2006-08-01

    Silicone based materials have attracted considerable attention from light emitting diode (LED) manufacturers for use as encapsulants and lenses for many high brightness LED (HB LED) devices. Currently silicones function in two key roles in HB LED devices, (1) as protective lenses and (2) stress relieving encapsulants for wire bond protection. The key attributes of silicones that make them attractive as light path materials for high brightness HB LEDs include their high transparency in the UV-visible region, controlled refractive index (RI), stable thermo-mechanical properties, and tuneable modulus from soft gels to hard resins. This paper will describe recent developments in moldable silicone hard resin materials. Progress on cavity moldable and liquid injection moldable (LIM) silicone compositions for discreet components is described. Also, an example of liquid injection overmolding is presented.

  15. Cracking assisted nucleation in chemical vapor deposition of silicon nanoparticles on silicon dioxide

    Microsoft Academic Search

    W. Thomas Leach; Jianhong Zhu; John G. Ekerdt

    2002-01-01

    Deposition of sub-monolayer silicon on SiO2\\/Si(100) greatly facilitates nucleation in subsequent thermal chemical vapor deposition (CVD) of silicon nanoparticles. Sub-monolayer seeding is accomplished using silicon atoms generated via disilane decomposition over a hot tungsten filament. The hot-wire process is nonselective towards deposition on silicon and SiO2, is insensitive to surface temperature below 825K, and gives controlled coverages well below 1ML.

  16. Activation of inwardly rectifying Kir2.x potassium channels by ? 3 -adrenoceptors is mediated via different signaling pathways with a predominant role of PKC for Kir2.1 and of PKA for Kir2.2

    Microsoft Academic Search

    Daniel Scherer; Claudia Kiesecker; Martin Kulzer; Myriam Günth; Eberhard P. Scholz; Sven Kathöfer; Dierk Thomas; Martin Maurer; Jörg Kreuzer; Alexander Bauer; Hugo A. Katus; Christoph A. Karle; Edgar Zitron

    2007-01-01

    ?3-adrenoceptors have recently been shown to induce a complex modulation of intracellular signaling pathways including cyclic\\u000a guanine monophosphate, cyclic adenosine monophosphate, Nitric oxide, and protein kinases A and C. They are expressed in a\\u000a broad variety of tissues including the myocardium, vascular smooth muscle, and endothelium. In those tissues, resting membrane\\u000a potential is controlled mainly by inwardly rectifying potassium channels

  17. Rectification of evanescent heat transfer between dielectric-coated and uncoated silicon carbide plates

    NASA Astrophysics Data System (ADS)

    Iizuka, Hideo; Fan, Shanhui

    2012-07-01

    Here, we show analytically that the thermal rectification via evanescent waves is obtained in the parallel semi-infinite bodies of the dielectric-coated silicon carbide and uncoated silicon carbide. The permittivity and the thickness of the dielectric coating are derived for maximizing the thermal rectification. In the nonequilibrium situation holding temperatures of 500 K for one body and 300 K for the other, either a coating with a high permittivity of 14 and a thickness of 1 nm or a coating with a low permittivity of 2 and a thickness exceeding 10 nm, results in rectifying coefficients of 0.4 to 0.44.

  18. Starting Material Silicon substrate

    E-print Network

    Healy, Kevin Edward

    2005 #12;N-Well Photo and Nitride Etch Silicon substrate Pad oxide Silicon nitride Photo resist Attila Horvath 2005 #12;P-Well Photo and Nitride Etch Silicon substrate Pad oxide Silicon nitride Photo resist N and Etch Silicon substrate Oxide N-WellP-Well P P NP Poly-Silicon Photo resist Attila Horvath 2005 #12;NMOS

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

    PubMed

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

    2015-02-13

    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

  20. A novel recovery of silicon nanoparticles from a waste silicon sludge.

    PubMed

    Jang, Hee Dong; Kim, Hyekyoung; Kil, Dae Sup; Chang, Hankwon

    2013-03-01

    As the semiconductor and photovoltaic industry undergo rapid growth, a large amount of silicon sludge is generated from the cutting process of silicon ingots. However, it is not effectively recycled. Recovery of nanometer-sized silicon (Si) particles from the sludge has become an important concern because the silicon sludge contains valuable resources including high purity silicon. In the present study, we investigated the novel recovery of Si nanoparticles from waste silicon sludge. The waste silicon sludge also contained surfactant, silicon carbide particles and metallic fragments. After removal of the surfactant by distillation, the Si nanoparticles were recovered by applying controlled ultrasonic waves and centrifugation in series. Metallic impurities in the recovered Si nanoparticles were purified by HCl treatment. The overall maximum yield and purity of the Si nanoparticles were about 80% and 99.7%, respectively. PMID:23755688

  1. Failure rates for accelerated acceptance testing of silicon transistors

    NASA Technical Reports Server (NTRS)

    Toye, C. R.

    1968-01-01

    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.

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

    PubMed

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

    2014-08-13

    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 Magnéli-like nanophases. The quantized conductance observed results in multiple well-defined resistance states suitable for implementation of multilevel memory cells. PMID:25072099

  3. A four level rectifier inverter system for drive applications

    Microsoft Academic Search

    G. Sinha; T.A. Lipo

    1998-01-01

    In a motor drive, the converters must be able to handle bidirectional real power flow. So far, DC voltage balancing has not been satisfactorily discussed for the case when real power is drawn from the inverter. This article addresses the control issues involved in a four-level inverter based AC drive application. The DC capacitor voltages are balanced for both motoring

  4. Current and voltage controlled capacitor charging schemes

    SciTech Connect

    Elwell, R.; Cherry, J.; Fagan, S. [Naval Surface Warfare Center, Annapolis, MD (United States)] [Naval Surface Warfare Center, Annapolis, MD (United States); Fish, S. [Inst. for Advanced Technology, Austin, TX (United States)] [Inst. for Advanced Technology, Austin, TX (United States)

    1995-01-01

    Future naval shipboard power systems for Electro-Thermal Chemical guns will require power conditioning to charge capacitors from a rectified generator source. This paper describes results of laboratory testing involving two low voltage capacitor charging schemes. These experiments demonstrate the power conditioning equipment`s voltage and current control characteristics. The first sequence of tests utilized a phase-controlled rectifier to control the current. A series of constant phase delay angles and a pre-determined phase delay angle profile were tested to produce a constant current charge on the capacitors. The second sequence utilized generator field control to ramp the charge voltage through a diode bridge to charge the capacitors. Using the results of each configuration, an optimum design of simultaneous current and voltage control can be developed. The control aspects of using combined generator field control and rectifier current control will be addressed.

  5. Hydrogen Sulfide Regulates Inward-Rectifying K+ Channels in Conjunction with Stomatal Closure1[OPEN

    PubMed Central

    Papanatsiou, Maria; Scuffi, Denisse; Blatt, Michael R.; García-Mata, Carlos

    2015-01-01

    Hydrogen sulfide (H2S) is the third biological gasotransmitter, and in animals, it affects many physiological processes by modulating ion channels. H2S has been reported to protect plants from oxidative stress in diverse physiological responses. H2S closes stomata, but the underlying mechanism remains elusive. Here, we report the selective inactivation of current carried by inward-rectifying K+ channels of tobacco (Nicotiana tabacum) guard cells and show its close parallel with stomatal closure evoked by submicromolar concentrations of H2S. Experiments to scavenge H2S suggested an effect that is separable from that of abscisic acid, which is associated with water stress. Thus, H2S seems to define a unique and unresolved signaling pathway that selectively targets inward-rectifying K+ channels. PMID:25770153

  6. Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

    NASA Astrophysics Data System (ADS)

    Shinohara, Naoki; Hatano, Ken

    2014-11-01

    In this paper, we show experimental results of RF-DC conversion with modulated 24GHz waves. We have already developed class-F MMIC rectenna with resonators for higher harmonics at no modulated 24GHz microwave for RF energy transfer. Dimensions of the MMIC rectifying circuit is 1 mm × 3 mm on GaAs. Maximum RF-DC conversion efficiency is measured 47.9% for a 210 mW microwave input of 24 GHz with a 120 ? load. The class-F rectenna is based on a single shunt full-wave rectifier. For future application of a simultaneous energy and information transfer system or an energy harvesting from broadcasting waves, input microwave will be modulated. In this paper, we show an experimental result of RF-DC conversion of the class-F rectenna with 24GHz waves modulated by 16QAM as 1st modulation and OFDM as 2nd modulation.

  7. Hydrogen sulfide regulates inward-rectifying k+ channels in conjunction with stomatal closure.

    PubMed

    Papanatsiou, Maria; Scuffi, Denisse; Blatt, Michael R; García-Mata, Carlos

    2015-05-01

    Hydrogen sulfide (H2S) is the third biological gasotransmitter, and in animals, it affects many physiological processes by modulating ion channels. H2S has been reported to protect plants from oxidative stress in diverse physiological responses. H2S closes stomata, but the underlying mechanism remains elusive. Here, we report the selective inactivation of current carried by inward-rectifying K(+) channels of tobacco (Nicotiana tabacum) guard cells and show its close parallel with stomatal closure evoked by submicromolar concentrations of H2S. Experiments to scavenge H2S suggested an effect that is separable from that of abscisic acid, which is associated with water stress. Thus, H2S seems to define a unique and unresolved signaling pathway that selectively targets inward-rectifying K(+) channels. PMID:25770153

  8. 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.

  9. Maximum power tracking control scheme for wind generator systems

    E-print Network

    Mena, Hugo Eduardo

    2009-05-15

    solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier...

  10. Maximum power tracking control scheme for wind generator systems

    E-print Network

    Mena Lopez, Hugo Eduardo

    2008-10-10

    solution to the complicated aerodynamic system. This control scheme provides a response to the wind changes without the knowledge of wind speed and turbine parameters. The system consists of a permanent magnet synchronous machine (PMSM), a passive rectifier...

  11. Production of electronic grade lunar silicon by disproportionation of silicon difluoride

    NASA Astrophysics Data System (ADS)

    Agosto, William N.

    1993-03-01

    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.

  12. Inverse agonist-like action of cadmium on G-protein-gated inward-rectifier K{sup +} channels

    SciTech Connect

    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

    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'.

  13. Resonant dc\\/dc Converter with Class E Inverter and Class E Synchronous Rectifier Using Thinned-Out Method

    Microsoft Academic Search

    Motoki Fujiit; Tadashi Suetugu; Hirotaka Koizumit; Kokichi Shinoda; Shinsaku Morit

    1995-01-01

    A new type of resonant DC\\/DC converter is proposed, analyzed and verified experimentally. The circuit is composed of a class D inverter and a class E synchronous rectifier. We apply the thinned-out method to the class E synchronous rectifier and regulate the output voltage at a fixed operating frequency. We have reduced the output voltage for the thinning-out operation in

  14. Three-Phase Isolated High-Power-Factor Rectifier Using Soft-Switched Two-Switch Forward Converter

    Microsoft Academic Search

    Yungtaek Jang; David L. Dillman; Milan M. Jovanovic

    2007-01-01

    A three-phase, high-power-factor (HPF), soft-switched isolated rectifier is introduced. The proposed circuit employs a discontinuous-voltage-mode (DVM) resonant input rectifier followed by a two-switch forward converter. In addition to achieving HPF rectification, the circuit also offers soft switching of the forward converter switches. The operation and performance of the proposed topology were verified on a 3-kW prototype operating from a three-phase

  15. A new approach to improve power factor and reduce harmonics in a three phase diode rectifier type utility interface

    Microsoft Academic Search

    S. Kim; P. Enjeti; P. Packebush; I. Pitel

    1993-01-01

    A novel approach to improving power factor and reducing harmonics generated by a three-phase diode-rectifier-type utility interface is proposed. This approach is passive and consists of a novel interconnection of a star\\/delta power transformer between the AC and DC sides of the diode rectifier topology. This interconnection, in combination with the 120° conduction intervals of each diode, is shown to

  16. Galantamine blocks delayed rectifier, but not transient outward potassium current in rat dissociated hippocampal pyramidal neurons

    Microsoft Academic Search

    Ya-Ping Pan; Xiang-Hua Xu; Xiao-Liang Wang

    2003-01-01

    Galantamine is an acetylcholinesterase inhibitor in Alzheimer's disease therapy. In the present study, we investigated the effects of galantamine on delayed rectifier potassium current (IK(DR)) and transient outward potassium current (IK(A)) in acutely dissociated rat hippocampal pyramidal neurons by using whole-cell patch clamp technique. IK(DR) was inhibited by galantamine in a concentration-dependent manner, while IK(A) remained unaffected. The IC50 value

  17. Verapamil block of the delayed rectifier K current in chick embryo dorsal root ganglion neurons

    Microsoft Academic Search

    Carlo Trequattrini; Luigi Catacuzzeno; Anna Petris; F. Franciolini

    1998-01-01

    We have used the patch-clamp method in the whole-cell configuration to investigate the mechanism of block of the delayed\\u000a rectifier K current (I\\u000a DRK) by verapamil in embryonic chick dorsal root ganglion (DRG) neurons. Verapamil induced a dose-dependent decay of the current,\\u000a without altering its activation kinetics. This observation, together with the good description of I\\u000a DRK time course at

  18. Molecular Dynamics Simulations of Inwardly Rectifying (Kir) Potassium Channels:  A Comparative Study †

    Microsoft Academic Search

    Shozeb Haider; Syma Khalid; Stephen J. Tucker; Frances M. Ashcroft; Mark S. P. Sansom

    2007-01-01

    Inward rectifier potassium (Kir) channels regulate cell excitability and transport K + ions across membranes. Homotetrameric models of three mammalian Kir channels (Kir1.1, Kir3.1, and Kir6.2) have been generated, using the KirBac3.1 transmembrane and rat Kir3.1 intracellular domain structures as templates. All three models have been explored by 10 ns molecular dynamics simulations in phospholipid bilayers. Analysis of the initial

  19. Design of an advanced high power density 1U intelligent rectifier

    Microsoft Academic Search

    F. Alecks; M. Ford; M. Tuffs

    2000-01-01

    This paper details both the challenges involved and the solutions proposed in the design of a very compact 2800 Watt intelligent telecom rectifier with a power density twice that of existing units (greater than 7.5 W per cubic inch or 0.46 W cm-3). The unit is 1U high and designed to fit in a 400 mm deep cabinet allowing high

  20. A new soft-switched resonant buck-type rectifier with constant switching frequency

    Microsoft Academic Search

    Jagjitpati Shukla; B. G. Fernandes

    2003-01-01

    A new three-phase soft-switched AC-to-DC buck converter operating at constant switching frequency and drawing current at unity power-factor from the source is proposed. Unlike other three-phase resonant switch buck-type rectifiers reported in the literature, the switching frequency of this converter is held constant. The proposed converter uses two switches, which are soft-switched. This results in reduced switching losses and electromagnetic

  1. A soft-switching mode rectifier with power factor correction and high frequency transformer link

    Microsoft Academic Search

    Chang-Ming Liaw; Thin-Huo Chen

    2000-01-01

    This paper presents a soft-switching mode rectifier (SSMR) consisting of a power factor correction zero-voltage-transition-pulse-width-modulated (PFC ZVT-PWM) converter and a high-frequency transformer-coupled DC\\/DC zero voltage switching clamped voltage (ZVS-CV) converter. An easily implemented ZVT soft-switching mechanism is developed to reduce the switching losses and stresses of the power switches in the PFC ZVT-PWM converter. The operations of the proposed SSMR

  2. An active power factor correction technique for three-phase diode rectifiers

    Microsoft Academic Search

    A. R. Prasad; Phoivos D. Ziogas; Stefanos Manias

    1991-01-01

    A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It

  3. An active power factor correction technique for three-phase diode rectifiers

    Microsoft Academic Search

    A. R. Prasad; P. D. Ziogas; S. Manias

    1989-01-01

    A novel active power factor correction method for power supplies with three-phase front-end diode rectifiers is proposed and analyzed. The implementation of this method requires the use of an additional single-switch boost chopper. The combined front-end converter draws sinusoidal AC currents from the AC source with nearly unity input power factor while operating at a fixed switching frequency. It is

  4. Development of a New Permanent-Magnet BLDC Generator Using 12Phase Half-Wave Rectifier

    Microsoft Academic Search

    Zhuoran Zhang; Yangguang Yan; Shanshui Yang; Zhou Bo

    2009-01-01

    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

  5. Soft-switched single-switch three-phase rectifier with power factor correction

    Microsoft Academic Search

    Slobodan GatariC; Dushan Boroyevich; Fred C. Lee

    1994-01-01

    Novel, zero-voltage-transition (ZVT) and zero-current-transition (ZCT) topologies of the single-switch three-phase boost power factor correction rectifier are proposed. The soft transition is achieved with a low-power auxiliary circuit employing an additional switch. The ZVT circuit is suitable for MOSFETs operating above 100 kHz, while the ZCT circuit can be used with IGBTs up to 50 kHz. Operation of the ZCT

  6. K-current fluctuations in inward-rectifying channels of frog skeletal muscle

    Microsoft Academic Search

    W. Schwarz; B. Neumcke; P. T. Palade

    1981-01-01

    Summary K currents and K-current fluctuations were recorded in inwardly rectifying K channels of frog skeletal muscle under voltage-clamp conditions. External application of 0.2 to 10mm Cs reduces the inward mean K current but produces a distinct increase of the spectral density of K-current fluctuations. The additional fluctuations arise from the random blocking by Cs ions. From the variance of

  7. Stability of a synchronous generator with diode-bridge rectifier and back-EMF load

    Microsoft Academic Search

    Ma Weiming; Hu An; Liu Dezhi; Zhang Gaifan

    2000-01-01

    An equivalent circuit model of a synchronous generator with diode-bridge rectifier and back-EMF load is presented in this paper. The principle of harmonic balance is applied, which makes it possible to construct a state-space mathematical model for the system. The criterion of stability is obtained for the system under small disturbances. This stability criterion is more accurate than that presented

  8. Effect of porous silicon on the performances of silicon solar cells during the porous silicon-based gettering procedure

    Microsoft Academic Search

    H. Nouri; M. Bouaïcha; B. Bessaïs

    2009-01-01

    In this work we analyse the effect of porous silicon on the performances of multicrystalline silicon (mc-Si) solar cells during the porous silicon-based gettering procedure. This procedure consists of forming PS layers on both front and back sides of the mc-Si wafers followed by an annealing in an infrared furnace under a controlled atmosphere at different temperatures. Three sets of

  9. Base Transport and Vertical Profile Engineering in SILICON\\/SILICON(1-X) Germanium(x)\\/silicon Heterojunction Bipolar Transistors

    Microsoft Academic Search

    Erwin Josef Prinz

    1992-01-01

    Recent advances in low-temperature epitaxial growth of strained silicon-germanium alloys on silicon substrates allow bandgap engineering in silicon-based devices, with profound consequences for device design. In this thesis the improved control by Rapid Thermal Chemical Vapor Deposition of the vertical profile of a Si\\/Si_{1-x}Ge _{x}\\/Si heterojunction bipolar transistor (HBT) is used to study the effect of the shape of the

  10. 2428 IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 23, NO. 5, SEPTEMBER 2008 A Modular Strategy for Control and Voltage

    E-print Network

    Paris-Sud XI, Université de

    ], [7]. The major drawback of the CHB converter, working as a voltage source inverter, is the need for Control and Voltage Balancing of Cascaded H-Bridge Rectifiers Hossein Iman-Eini, Jean-Luc Schanen, Senior for voltage balancing of distinct dc buses in cascaded H-bridge rectifiers is presented. This method ensures

  11. Microfluidic rectifier based on poly(dimethylsiloxane) membrane and its application to a micropump.

    PubMed

    Wang, Yao-Nan; Tsai, Chien-Hsiung; Fu, Lung-Ming; Lin Liou, Lung-Kai

    2013-01-01

    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

  12. Capacity of Rectified Vestibular Evoked Myogenic Potential in Correcting Asymmetric Muscle Contraction Power

    PubMed Central

    Kim, Kun Woo; Jung, Jae Yun; Lee, Jeong Hyun

    2013-01-01

    Objectives Rectified vestibular evoked myogenic potential (rVEMP) is new method that simultaneously measures the muscle contraction power during VEMP recordings. Although there are a few studies that have evaluated the effect of the rVEMP, there is no study that has evaluated the capacity of rVEMP during asymmetrical muscle contraction. Methods Thirty VEMP measurements were performed among 20 normal subjects (mean age, 28.2±2.1 years; male, 16). VEMP was measured in the supine position. The head was turned to the right side by 0°, 15°, 30°, and 45° and the VEMPs were recorded in each position. The interaural amplitude difference (IAD) ratio was calculated by the conventional non-rectified VEMP (nVEMP) and rVEMP. Results The nVEMP IAD increased significantly according to increasing neck rotation. The IAD in rVEMP was almost similar from 0° to 30°. However, the IAD was significantly larger than the other positions when the neck was rotated 45°. When IAD during 0° was set as a standard, the IAD of the rVEMP was significantly smaller that the nVEMP only during the 30°rotaion. Conclusion Rectified VEMP is capable of correcting asymmetrical muscle contraction power. In contrast, it cannot correct the asymmetry if muscle contraction power asymmetry is 44.8% or larger. Also, it is not necessary if muscle contraction power asymmetry is 22.5% or smaller. PMID:24353859

  13. Microfluidic rectifier based on poly(dimethylsiloxane) membrane and its application to a micropump

    PubMed Central

    Wang, Yao-Nan; Tsai, Chien-Hsiung; Fu, Lung-Ming; Lin Liou, Lung-Kai

    2013-01-01

    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

  14. Multi-Service Highly Sensitive Rectifier for Enhanced RF Energy Scavenging

    PubMed Central

    Shariati, Negin; Rowe, Wayne S. T.; Scott, James R.; Ghorbani, Kamran

    2015-01-01

    Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478–496 and 852–869?MHz) and exhibits favorable impedance matching over a broad input power range (?40 to ?10?dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8?mV is achieved for a multi-tone input power of ?10?dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860?MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments. PMID:25951137

  15. Multi-service highly sensitive rectifier for enhanced RF energy scavenging.

    PubMed

    Shariati, Negin; Rowe, Wayne S T; Scott, James R; Ghorbani, Kamran

    2015-01-01

    Due to the growing implications of energy costs and carbon footprints, the need to adopt inexpensive, green energy harvesting strategies are of paramount importance for the long-term conservation of the environment and the global economy. To address this, the feasibility of harvesting low power density ambient RF energy simultaneously from multiple sources is examined. A high efficiency multi-resonant rectifier is proposed, which operates at two frequency bands (478-496 and 852-869?MHz) and exhibits favorable impedance matching over a broad input power range (-40 to -10?dBm). Simulation and experimental results of input reflection coefficient and rectified output power are in excellent agreement, demonstrating the usefulness of this innovative low-power rectification technique. Measurement results indicate an effective efficiency of 54.3%, and an output DC voltage of 772.8?mV is achieved for a multi-tone input power of -10?dBm. Furthermore, the measured output DC power from harvesting RF energy from multiple services concurrently exhibits a 3.14 and 7.24 fold increase over single frequency rectification at 490 and 860?MHz respectively. Therefore, the proposed multi-service highly sensitive rectifier is a promising technique for providing a sustainable energy source for low power applications in urban environments. PMID:25951137

  16. Low cost, p-ZnO/n-Si, rectifying, nano heterojunction diode: Fabrication and electrical characterization

    PubMed Central

    Kabra, Vinay; Malik, M M

    2014-01-01

    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 current–voltage (I–V) and capacitance–voltage (C–V) measurements. The effect of UV illumination on the I–V 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

  17. Mitigating impact of thermal and rectified radio-frequency sheath potentials on edge localized modes

    NASA Astrophysics Data System (ADS)

    Gui, B.; Xu, X. Q.; Myra, J. R.; D'Ippolito, D. A.

    2014-11-01

    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.

  18. Improvement in rectification ratio of an Al-based bulk thermal rectifier working at high temperatures

    NASA Astrophysics Data System (ADS)

    Takeuchi, Tsunehiro; Goto, Hiroki; Nakayama, Ryu-suke; Terazawa, Yu-ichi; Ogawa, Koto; Yamamoto, Akio; Itoh, Takashi; Mikami, Masashi

    2012-05-01

    In this study, we attempted to improve the thermal rectification ratio (TRR = (JAB - JBA)/JBA) of a thermal rectifier consisting of two Al-based alloys, Al72.6Re17.4Si10 and Al71.6Mn17.4Si11, both of which are known to be the 1/1-cubic approximant of icosahedral quasicrystal. In order to estimate the thermal rectification ratio obtainable for a thermal rectifier made from two given materials, we employed a simple method of TRR calculation using the classical Fourier-law of heat conduction. The largest TRR, which exceeded 0.12 for the thermal reservoirs kept at TH = 500 K and TL = 300 K, was experimentally obtained, coinciding with what the calculations predicted. By using the experimentally determined thermal conductivity and the calculation method employed in this study, we show the potential of an Al62Cu25.5Fe12.5 icosahedral quasicrystal as one of the constituent materials of thermal rectifier possessing a TRR magnitude in excess of unity.

  19. Growth by rectified diffusion of strongly acoustically forced gas bubbles in nearly saturated liquids.

    PubMed

    Louisnard, Olivier; Gomez, Francisco

    2003-03-01

    The growth or dissolution of small gas bubbles (R0<15 microm) by rectified diffusion in nearly saturated liquids, subject to low frequencies (20 kHzrectified diffusion threshold radius merges with the Blake threshold radius, which means that a growing bubble is also an inertially oscillating bubble. On the assumption that such a bubble keeps its integrity up to the shape instability threshold predicted by single-bubble theory, a numerical estimation and a fully analytical approximation of its growth rate are derived. On the one hand, the merging of the two thresholds raises the problem of the construction and self-sustainment of acoustic cavitation fields. On the other hand, the lifetime of the growing inertial bubbles calculated within the present theory is found to be much shorter than the time necessary to rectify argon. This allows an alternative interpretation of the absence of single-bubble sonoluminescence emission in multibubble fields, without resorting to the conventional picture of shape instabilities caused by the presence of other bubbles. PMID:12689182

  20. Low cost, p-ZnO/n-Si, rectifying, nano heterojunction diode: Fabrication and electrical characterization.

    PubMed

    Kabra, Vinay; Aamir, Lubna; Malik, M M

    2014-01-01

    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 current-voltage (I-V) and capacitance-voltage (C-V) measurements. The effect of UV illumination on the I-V 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

  1. Gating mechanism of the cloned inward rectifier potassium channel from mouse heart.

    PubMed

    Ishihara, K; Hiraoka, M

    1994-10-01

    The complementary DNA encoding the inward rectifier potassium channel was cloned from the adult mouse heart by using the polymerase chain reaction. The clone had the nucleotide sequence identical to that of the IRK1 gene cloned from a mouse macrophage cell line. Northern blot analysis revealed that the transcript of this gene was mainly expressed in the ventricle, where the inward rectifier K+ channel plays a predominant role in maintaining the high negative value of the resting membrane potential. The current expressed by injection of the complementary RNA of the cloned gene into Xenopus oocytes showed a marked inward rectification that depends on the driving force of K+. A region of negative slope conductance was observed in the current-voltage relationship at potentials positive to the reversal potential. When the extracellular K+ concentration was raised, the increase in outward current amplitude resulted in the "crossover" of outward current-voltage relations. The fast time-dependent increase in current amplitude was recorded upon membrane repolarization from a potential positive to the reversal potential. The kinetics of the time-dependent current was very similar to that of the intrinsic gating mechanism of the native cardiac inward rectifier K+ channel. Our results suggest the existence of the intrinsic gating mechanism, accounting for the extent of rectification in the current-voltage relationship in the expressed channel. PMID:7707353

  2. Silicon/organic Silicon/metal

    E-print Network

    Petta, Jason

    Silicon/organic Silicon/metal Silicon/Organic Heterojunctions for Photovoltaics (DMR-0819860) IRG photon creates an electron (black circle in top sketch) and a hole (open circle). For maximum efficiency on the surface of silicon. The wide gap (shown in red) blocks electrons from spilling into the anode. Organic

  3. Silicon microdosimetry.

    PubMed

    Agosteo, Stefano; Pola, Andrea

    2011-02-01

    Silicon detectors are being studied as microdosemeters since they can provide sensitive volumes of micrometric dimensions. They can be applied for assessing single-event effects in electronic instrumentation exposed to complex fields around high-energy accelerators or in space missions. When coupled to tissue-equivalent converters, they can be used for measuring the quality of radiation therapy beams or for dosimetry. The use of micrometric volumes avoids the contribution of wall effects to the measured spectra. Further advantages of such detectors are their compactness, cheapness, transportability and a low sensitivity to vibrations. The following problems need to be solved when silicon devices are used for microdosimetry: (i) the sensitive volume has to be confined in a region of well-known dimensions; (ii) the electric noise limits the minimum detectable energy; (iii) corrections for tissue-equivalency should be made; (iv) corrections for shape equivalency should be made when referring to a spherical simulated site of tissue; (v) the angular response should be evaluated carefully; (vi) the efficiency of a single detector of micrometric dimensions is very poor and detector arrays should be considered. Several devices have been proposed as silicon microdosemeters, based on different technologies (telescope detectors, silicon on insulator detectors and arrays of cylindrical p-n junctions with internal amplification), in order to satisfy the issues mentioned above. PMID:21112892

  4. Phosphatidylinositol-4,5-bisphosphate (PIP2) regulation of strong inward rectifier Kir2.1 channels: multilevel positive cooperativity

    PubMed Central

    Xie, Lai-Hua; John, Scott A; Ribalet, Bernard; Weiss, James N

    2008-01-01

    Inwardly rectifying potassium (Kir) channels are gated by the interaction of their cytoplasmic regions with membrane-bound phosphatidylinositol-4,5-bisphosphate (PIP2). In the present study, we examined how PIP2 interaction regulates channel availability and channel openings to various subconductance levels (sublevels) as well as the fully open state in the strong inward rectifier Kir2.1 channel. Various Kir2.1 channel constructs were expressed in Xenopus oocytes and single channel or macroscopic currents were recorded from inside-out patches. The wild-type (WT) channel rarely visited the subconductance levels under control conditions. However, upon reducing Kir2.1 channel interaction with PIP2 by a variety of interventions, including PIP2 antibodies, screening PIP2 with neomycin, or mutating PIP2 binding sites (e.g. K188Q), visitation to the sublevels was markedly increased before channels were converted to an unavailable mode in which they did not open. No channel activity was detected in channels with the double mutation K188A/R189A, a mutant which exhibits extremely weak interaction with PIP2. By linking subunits together in tandem dimers or tetramers containing mixtures of WT and K188A/R189A subunits, we demonstrate that one functional PIP2-interacting WT subunit is sufficient to convert channels from the unavailable to the available mode with a high open probability dominated by the fully open state, with similar kinetics as tetrameric WT channels. Occasional openings to sublevels become progressively less frequent as the number of WT subunits increases. Quantitative analysis reveals that the interaction of PIP2 with WT subunits exerts strong positive cooperativity in both converting the channels from the unavailable to the available mode, and in promoting the fully open state over sublevels. We conclude that the interaction of PIP2 with only one Kir2.1 subunit is sufficient for the channel to become available and to open to its full conductance state. Interaction with additional subunits exerts positive cooperativity at multiple levels to further enhance channel availability and promote the fully open state. PMID:18276733

  5. Monolithic silicon waveguides in bulk silicon wafers

    NASA Astrophysics Data System (ADS)

    Chang, Chia-Ming; Solgaard, Olav

    2014-02-01

    We demonstrate two silicon photonic technologies for fabrication of monolithic photonic devices in standard silicon. Using these technologies, we demonstrate low-loss silicon waveguides (2.34 dB/cm), double-layer 3D waveguides, and waveguide Bragg reflectors in standard silicon for optical interconnects and sensing applications. These technologies simplify integration of electronics and photonics and are possible alternatives to SOI-based technology for implementation of silicon-photonic devices and systems for optical interconnects and sensing.

  6. Semiconductor systems utilizing materials that form rectifying junctions in both N and P-type doping regions, whether metallurgically or field induced, and methods of use

    DOEpatents

    Welch, James D. (10328 Pinehurst Ave., Omaha, NE 68124)

    2000-01-01

    Disclosed are semiconductor systems, such as integrated circuits utilizing Schotky barrier and/or diffused junction technology, which semiconductor systems incorporate material(s) that form rectifying junctions in both metallurgically and/or field induced N and P-type doping regions, and methods of their use. Disclosed are Schottky barrier based inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems and which can be operated as modulators, N and P-channel MOSFETS and CMOS formed therefrom, and (MOS) gate voltage controlled rectification direction and gate voltage controlled switching devices, and use of such material(s) to block parasitic current flow pathways. Simple demonstrative five mask fabrication procedures for inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to multiple device CMOS systems are also presented.

  7. In situ ZnO nanowire growth to promote the PVDF piezo phase and the ZnO-PVDF hybrid self-rectified nanogenerator as a touch sensor.

    PubMed

    Li, Zetang; Zhang, Xu; Li, Guanghe

    2014-03-28

    A PVDF-ZnO nanowires (NWs) hybrid generator (PZHG) was designed. A simple, cost effective method to produce the PVDF ? phase by nano force is introduced. With the ZnO NWs growing, the in situ nano extension force promotes the phase change. A theoretical analysis of the ZnO NWs acting as a self-rectifier of the nano generator is established. The ZnO NWs acted as a self-adjustment diode to control the current output of the PZHG by piezo-electric and semi-conductive effects. Based on the self-controllability of the piezoelectric output, three kinds of finger touching are distinguished by the output performances of the PZHG, which is applicable to an LCD touch pad. PMID:24515250

  8. Damage Mechanisms and Controlled Crack Propagation in a Hot Pressed Silicon Nitride Ceramic. Ph.D. Thesis - Northwestern Univ., 1993

    NASA Technical Reports Server (NTRS)

    Calomino, Anthony Martin

    1994-01-01

    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.

  9. Silicon Nanowire Devices

    NASA Astrophysics Data System (ADS)

    Kamins, Theodore

    2006-03-01

    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.

  10. Versatile control of metal-assisted chemical etching for vertical silicon microwire arrays and their photovoltaic applications.

    PubMed

    Um, Han-Don; Kim, Namwoo; Lee, Kangmin; Hwang, Inchan; Hoon Seo, Ji; Yu, Young J; Duane, Peter; Wober, Munib; Seo, Kwanyong

    2015-01-01

    A systematic study was conducted into the use of metal-assisted chemical etching (MacEtch) to fabricate vertical Si microwire arrays, with several models being studied for the efficient redox reaction of reactants with silicon through a metal catalyst by varying such parameters as the thickness and morphology of the metal film. By optimizing the MacEtch conditions, high-quality vertical Si microwires were successfully fabricated with lengths of up to 23.2??m, which, when applied in a solar cell, achieved a conversion efficiency of up to 13.0%. These solar cells also exhibited an open-circuit voltage of 547.7?mV, a short-circuit current density of 33.2?mA/cm(2), and a fill factor of 71.3% by virtue of the enhanced light absorption and effective carrier collection provided by the Si microwires. The use of MacEtch to fabricate high-quality Si microwires therefore presents a unique opportunity to develop cost-effective and highly efficient solar cells. PMID:26060095

  11. Versatile control of metal-assisted chemical etching for vertical silicon microwire arrays and their photovoltaic applications

    PubMed Central

    Um, Han-Don; Kim, Namwoo; Lee, Kangmin; Hwang, Inchan; Hoon Seo, Ji; Yu, Young J.; Duane, Peter; Wober, Munib; Seo, Kwanyong

    2015-01-01

    A systematic study was conducted into the use of metal-assisted chemical etching (MacEtch) to fabricate vertical Si microwire arrays, with several models being studied for the efficient redox reaction of reactants with silicon through a metal catalyst by varying such parameters as the thickness and morphology of the metal film. By optimizing the MacEtch conditions, high-quality vertical Si microwires were successfully fabricated with lengths of up to 23.2??m, which, when applied in a solar cell, achieved a conversion efficiency of up to 13.0%. These solar cells also exhibited an open-circuit voltage of 547.7?mV, a short-circuit current density of 33.2?mA/cm2, and a fill factor of 71.3% by virtue of the enhanced light absorption and effective carrier collection provided by the Si microwires. The use of MacEtch to fabricate high-quality Si microwires therefore presents a unique opportunity to develop cost-effective and highly efficient solar cells. PMID:26060095

  12. Controlled translocation of DNA through nanopores in carbon nano-, silicon-nitride- and lipid-coated membranes.

    PubMed

    Sischka, Andy; Galla, Lukas; Meyer, Andreas J; Spiering, Andre; Knust, Sebastian; Mayer, Michael; Hall, Adam R; Beyer, André; Reimann, Peter; Gölzhäuser, Armin; Anselmetti, Dario

    2015-07-21

    We investigated experimentally and theoretically the translocation forces when a charged polymer is threaded through a solid-state nanopore and found distinct dependencies on the nanopore diameter as well as on the nano membrane material chemistry. For this purpose we utilized dedicated optical tweezers force mechanics capable of probing the insertion of negatively charged double-stranded DNA inside a helium-ion drilled nanopore. We found that both the diameter of the nanopore and the membrane material itself have significant influences on the electroosmotic flow through the nanopore and thus on the threading force. Compared to a bare silicon-nitride membrane, the threading of DNA through only 3 nm thin carbon nano membranes as well as lipid bilayer-coated nanopores increased the threading force by 15% or 85%, respectively. This finding was quantitatively described by our recently developed theoretical model that also incorporates hydrodynamic slip effects on the translocating DNA molecule and the force dependence on the membrane thickness. The additional measurements presented in this paper further support our model. PMID:25768647

  13. Silicon radiation detectors

    Microsoft Academic Search

    Pavel Rehak

    2003-01-01

    A rapid progress of past 20 years in silicon radiation detectors is reviewed. The availability of silicon as almost ideal semiconductor material is one of the main reasons for this progress. The well-defined properties of the silicon-silicon dioxide interface allowed the development of detector structures beyond the structure of a classical diode detector, which was practically the only silicon detector

  14. Eliciting Renal Failure in Mosquitoes with a Small-Molecule Inhibitor of Inward-Rectifying Potassium Channels

    PubMed Central

    Raphemot, Rene; Rouhier, Matthew F.; Hopkins, Corey R.; Gogliotti, Rocco D.; Lovell, Kimberly M.; Hine, Rebecca M.; Ghosalkar, Dhairyasheel; Longo, Anthony; Beyenbach, Klaus W.; Denton, Jerod S.; Piermarini, Peter M.

    2013-01-01

    Mosquito-borne diseases such as malaria and dengue fever take a large toll on global health. The primary chemical agents used for controlling mosquitoes are insecticides that target the nervous system. However, the emergence of resistance in mosquito populations is reducing the efficacy of available insecticides. The development of new insecticides is therefore urgent. Here we show that VU573, a small-molecule inhibitor of mammalian inward-rectifying potassium (Kir) channels, inhibits a Kir channel cloned from the renal (Malpighian) tubules of Aedes aegypti (AeKir1). Injection of VU573 into the hemolymph of adult female mosquitoes (Ae. aegypti) disrupts the production and excretion of urine in a manner consistent with channel block of AeKir1 and renders the mosquitoes incapacitated (flightless or dead) within 24 hours. Moreover, the toxicity of VU573 in mosquitoes (Ae. aegypti) is exacerbated when hemolymph potassium levels are elevated, suggesting that Kir channels are essential for maintenance of whole-animal potassium homeostasis. Our study demonstrates that renal failure is a promising mechanism of action for killing mosquitoes, and motivates the discovery of selective small-molecule inhibitors of mosquito Kir channels for use as insecticides. PMID:23734226

  15. Microfluidic assembly of monodisperse multistage pH-responsive polymer/porous silicon composites for precisely controlled multi-drug delivery.

    PubMed

    Liu, Dongfei; Zhang, Hongbo; Herranz-Blanco, Bárbara; Mäkilä, Ermei; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2014-05-28

    We report an advanced drug delivery platform for combination chemotherapy by concurrently incorporating two different drugs into microcompoistes with ratiometric control over the loading degree. Atorvastatin and celecoxib were selected as model drugs due to their different physicochemical properties and synergetic effect on colorectal cancer prevention and inhibition. To be effective in colorectal cancer prevention and inhibition, the produced microcomposite contained hypromellose acetate succinate, which is insoluble in acidic conditions but highly dissolving at neutral or alkaline pH conditions. Taking advantage of the large pore volume of porous silicon (PSi), atorvastatin was firstly loaded into the PSi matrix, and then encapsulated into the pH-responsive polymer microparticles containing celecoxib by microfluidics in order to obtain multi-drug loaded polymer/PSi microcomposites. The prepared microcomposites showed monodisperse size distribution, multistage pH-response, precise ratiometric controlled loading degree towards the simultaneously loaded drug molecules, and tailored release kinetics of the loaded cargos. This attractive microcomposite platform protects the payloads from being released at low pH-values, and enhances their release at higher pH-values, which can be further used for colon cancer prevention and treatment. Overall, the pH-responsive polymer/PSi-based microcomposite can be used as a universal platform for the delivery of different drug molecules for combination therapy. PMID:24616278

  16. Silicon Micromachined Microlens Array for THz Antennas

    NASA Technical Reports Server (NTRS)

    Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

    2013-01-01

    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.

  17. A study on high current rectifier systems with mitigated time-varying magnetic field generation at ac input and dc output busbars

    Microsoft Academic Search

    Yongsug Suh; Changwoo Kim

    2011-01-01

    This paper investigates occupational exposure to time-varying magnetic field generation in high power rectifier systems. Two different kinds of high power rectifier systems rated for 25kA are modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP(International Commission on Non-Ionizing Radiation Protection). In order to focus on the qualitative effect of rectifier operation,

  18. Microscopic theory of hydrogen in silicon devices

    Microsoft Academic Search

    Chris G. Van de Walle; Blair R. Tuttle

    2000-01-01

    Incorporation of hydrogen has a strong effect on the characteristics of silicon devices. A fundamental understanding of the microscopic mechanisms is required in order to monitor and control the behavior of hydrogen. First-principles calculations have been instrumental in providing such understanding. We first outline the basic principles that govern the interaction between hydrogen and silicon, followed by an overview of

  19. High Performance Silicon Nanowire Field Effect Transistors

    Microsoft Academic Search

    Yi Cui; Zhaohui Zhong; Deli Wang; Wayne U. Wang; Charles M. Lieber

    2003-01-01

    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.

  20. Formation and characterization of cobalt 6H-silicon carbide Schottky contacts

    NASA Astrophysics Data System (ADS)

    Lundberg, N.; Östling, M.

    1993-11-01

    Rectifying Schottky contacts using e-beam evaporation of cobalt have been demonstrated on n-type silicon face 6H-SiC. Examination of the electrical properties was performed by I-V and C-V measurements as a function of annealing temperature in the 300-900 °C range for 1 h. Excellent rectifying behavior was found up to 700 °C. Heat treatments at 800-900 °C formed different cobalt silicides (Co2Si and CoSi) containing homogeneously distributed carbon with carbon agglomerates at the surface. Consecutive annealings from 300 to 800 °C increased the barrier height from 0.8 to 1.3 eV and the ideality factor from 1.15 to 1.46. Heat treatments at 900 °C modified the contacts into an ohmic behavior.

  1. Making silicon stronger.

    SciTech Connect

    Boyce, Brad Lee

    2010-11-01

    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.

  2. Imaging crystal orientations in multicrystalline silicon wafers via photoluminescence

    E-print Network

    it is convenient to texture monocrystalline silicon wafers with a (100) surface orientation through alkaline etchImaging crystal orientations in multicrystalline silicon wafers via photoluminescence H. C. Sio, Z crystallization of amorphous silicon: Controlled nanosecond studies in the dynamic transmission electron

  3. Superhydrophobic silicone fiber mats fabricated by electrospinning from solution

    Microsoft Academic Search

    Bonnie Ludwig; Aneta Clark; Steven Snow; Randal Hill; Randall Schmidt; Brad Fogg; Peter Lo

    2007-01-01

    Fine silicone fibers of 1 -- 20 mum diameter were fabricated from solution via electrospinning. These are the first examples of fine fibers prepared from silicone homopolymers. Fiber morphology (beaded, ribbon-like, smooth) and diameter were controlled. The nanoscale surface roughness of nonwoven fiber mats created with silicone fibers produced a superhydrophobic surface that had a water contact angle of ˜160^o.

  4. Characterization of silicon oxide gas barrier films with controlling to the ion current density (ion flux) by plasma enhanced chemical vapor deposition

    Microsoft Academic Search

    Su B. Jin; Youn J. Kim; Yoon S. Choi; In S. Choi; Jeon G. Han

    2010-01-01

    Silicon oxide gas barrier films were deposited on polyethylene terephthalate (PET) substrates by plasma enhanced chemical vapor deposition (PE-CVD) for applications to transparent barrier packaging. The barrier properties of the silicon oxide coated film were optimized by varying the bias conditions and input power in the radio frequency plasma. The plasma diagnostics, ion current density and substrate temperature were characterized

  5. Coulomb blockade, single-electron transistors and circuits in silicon

    Microsoft Academic Search

    Zahid A. K Durrani

    2003-01-01

    Single-electron devices in silicon provide a means to control the electrons in nanoscale electronic systems precisely while retaining compatibility with large-scale integrated (LSI) circuit technology. Single-electron transistors operating at room temperature have now been fabricated in silicon-on-insulator, polycrystalline silicon, and nanocrystalline silicon material. Memory cells where the stored states are defined by single electrons, and few-electron memory cell arrays with

  6. Identification of common synaptic inputs to motor neurons from the rectified electromyogram

    PubMed Central

    Farina, Dario; Negro, Francesco; Jiang, Ning

    2013-01-01

    Oscillatory common inputs of cortical or peripheral origin can be identified from the motor neuron output with coherence analysis. Linear transmission is possible despite the motor neuron non-linearity because the same input is sent commonly to several neurons. Because of the linear transmission, common input components to motor neurons can be investigated from the surface EMG, for example by EEG–EMG or EMG–EMG coherence. In these studies, there is an open debate on the utility and appropriateness of EMG rectification. The present study addresses this issue using an analytical, simulation and experimental approach. The main novel theoretical contribution that we report is that the spectra of both the rectified and the raw EMG contain input spectral components to motor neurons. However, they differ by the contribution of amplitude cancellation which influences the rectified EMG spectrum when extracting common oscillatory inputs. Therefore, the degree of amplitude cancellation has an impact on the effectiveness of EMG rectification in extracting input spectral peaks. The theoretical predictions were exactly confirmed by realistic simulations of a pool of motor neurons innervating a muscle in a cylindrical volume conductor of EMG generation and by experiments conducted on the first dorsal interosseous and the abductor pollicis brevis muscles of seven healthy subjects during pinching. It was concluded that when the contraction level is relatively low, EMG rectification may be preferable for identifying common inputs to motor neurons, especially when the energy of the action potentials in the low frequency range is low. Nonetheless, different levels of cancellation across conditions influence the relative estimates of the degree of linear transmission of oscillatory inputs to motor neurons when using the rectified EMG. PMID:23507877

  7. Modulation of the inwardly rectifying potassium channel IRK1 by the m1 muscarinic receptor.

    PubMed

    Jones, S V

    1996-04-01

    Modulation of the inwardly rectifying potassium channel (IRK1) by the m1 muscarinic receptor was studied with the whole-cell patch-clamp recording technique with the use of a mammalian expression system. After transfection with IRK1 and m1 muscarinic receptor genes, tsA cells expressed a cesium-sensitive inwardly rectifying potassium conductance that was reduced on application of the muscarinic receptor agonist carbachol. This reduction was reversible on washout of carbachol and could be completely inhibited by the muscarinic receptor antagonist atropine. Conversely, stimulation of the m2 muscarinic receptor, when coexpressed with IRK1, resulted in no change in IRK1 current amplitude. Phorbol-12, 13-dibutyrate, an activator of protein kinase c (PKC), mimicked the effect of m1 muscarinic receptor stimulation by inhibiting the IRK1 conductance. Preincubation with staurosporine or the specific PKC inhibitor calphostin C, before application of carbachol, fully prevented the inhibition of IRK1 by m1 muscarinic receptor stimulation. Administration of 8-bromo-cAMP, an activator of protein kinase A, and thapsigargin, a stimulator of intracellular calcium release, had no effect on IRK1, suggesting that these second messengers were not involved in the m1 muscarinic receptor-induced response. Therefore, the data indicate that the m1 muscarinic receptor inhibits IRK1, presumably via stimulation of PKC. As IRK1 is widely distributed throughout the central nervous system, it is possible that such an action on IRK1 underlies the inhibitory effects of muscarinic receptor stimulation on inwardly rectifying potassium conductances observed in the brain. PMID:8609894

  8. Comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier.

    PubMed

    Tsai, Cheng-Tao; Su, Jye-Chau; Tseng, Sheng-Yu

    2013-01-01

    This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500?W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications. PMID:24381521

  9. Rectified motion in an asymmetric channel: The role of hydrodynamic interactions with walls

    NASA Astrophysics Data System (ADS)

    Golshaei, Behzad; Najafi, Ali

    2015-02-01

    Dynamics of a Brownian particle in an asymmetric microchannel 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 in an approximate way. 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.

  10. Rectified motion in an asymmetric channel: the role of hydrodynamic interactions with walls.

    PubMed

    Golshaei, Behzad; Najafi, Ali

    2015-02-01

    Dynamics of a Brownian particle in an asymmetric microchannel 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 in an approximate way. 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. PMID:25768452

  11. Rectifiable oscillations of self-adjoint and damped linear differential equations of second-order

    Microsoft Academic Search

    Mervan Paši?; Satoshi Tanaka

    2011-01-01

    Asymptotic and oscillatory behaviours near x=0 of all solutions y=y(x) of self-adjoint linear differential equation (Ppq): (py?)?+qy=0 on (0,T], will be studied, where p=p(x) and q=q(x) satisfy the so-called Hartman–Wintner type condition. We show that the oscillatory behaviour near x=0 of (Ppq) is characterised by the nonintegrability of q\\/p on (0,T). Moreover, under this condition, we show that the rectifiable

  12. Cardiac and Renal Inward Rectifier Potassium Channel Pharmacology: Emerging Tools for Integrative Physiology and Therapeutics

    PubMed Central

    Swale, Daniel R.; Kharade, Sujay V.; Denton, Jerod S.

    2014-01-01

    Inward rectifier potassium (Kir) channels play fundamental roles in cardiac and renal function and may represent unexploited drug targets for cardiovascular diseases. However, the limited pharmacology of Kir channels has slowed progress toward exploring their integrative physiology and therapeutic potential. Here, we review recent progress toward developing the small-molecule pharmacology for Kir2.x, Kir4.1, and Kir7.1 and discuss common mechanistic themes that may help guide future Kir channel-directed drug discovery efforts. PMID:24721648

  13. Rectified motion in an asymmetric channel: the role of hydrodynamic interactions with walls

    E-print Network

    B. Golshaei; A. Najafi

    2014-09-28

    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.

  14. High Precision HalfWave Rectifier Circuit In Dual Phase Output Mode

    E-print Network

    Jamjaem, Theerayut

    2010-01-01

    This paper present high precision halfwave rectifier circuit in dual phase output mode by 0.5 micrometer CMOS technology, plus or minus 1.5 V low voltage, it has received input signal and sent output current signal, respond in high frequency. The main structure compound with CMOS inverter circuit, common source circuit, and current mirror circuit. Simulation and confirmation quality of working by PSpice program, then it able to operating at maximum frequency about 100 MHz, maximum input current range about 400 \\mu Ap p, high precision output signal, low power dissipation, and uses a little transistor.

  15. Riesz $s$-equilibrium measures on $d$-rectifiable sets as $s$ approaches $d$

    E-print Network

    M. T. Calef; D. P. Hardin

    2008-08-28

    Let $A$ be a compact set in ${\\mathbb R}^p$ of Hausdorff dimension $d$. For $s\\in(0,d)$, the Riesz $s$-equilibrium measure $\\mu^s$ is the unique Borel probability measure with support in $A$ that minimizes $$ I_s(\\mu):=\\iint\\frac{1}{|x-y|^s}d\\mu(y)d\\mu(x)$$ over all such probability measures. If $A$ is strongly $({\\mathcal H}^d, d)$-rectifiable, then $\\mu^s$ converges in the weak-star topology to normalized $d$-dimensional Hausdorff measure restricted to $A$ as $s$ approaches $d$ from below.

  16. Control and expression of -NH2, -SH, -COOH and SiO2 on the surface of silicon carbide quantum dots

    NASA Astrophysics Data System (ADS)

    Mwania, Munuve; Aguirre-Medel, Susana; Kroll, Peter

    2015-03-01

    We present simple protocols for reliably tailoring the surfaces of zinc blende silicon carbide quantum dots (?-SiC QDs). The SiC QDs are synthesized via photo-assisted electrochemical corrosion of bulk powders at different temperatures and time scales. After washing the residual acid and resuspending in H2O, the surfaces of SiC QDs were controllably coated with four different functional groups, specifically -NH2, -SH, and -COOH and -SiO2. We began by covalently attaching primary amines (-NH2) to the QD surface. The amine terminations were then converted to amine/thiolate (-NH2/SH) and amine/carboxylate (-NH2/COOH) functional groups. SiO2 shells around SiC QDs (to create SiC@SiO2nano-structures) were grown using a TEOS-mediated Stöber method. The presence of amine and thiol groups was confirmed by fluoresceamine assay test, X-ray photoelectron spectroscopy (XPS) and infrared spectroscopy (FTIR). While a negative fluoresceamine assay test confirmed the replacement of amine groups by thiol groups, the thiolation of the surface was also confirmed through Ellman's assay, XPS and FTIR. The presence of the SiO2 shells was examined using transmission electron microscopy and XPS. Our results open up possibilities to manipulate SiC QDs for various applications.

  17. LETTER Communicated by M. V. Srinivasan and Stephen DeWeerth A Silicon Implementation of the Fly's Optomotor Control

    E-print Network

    Harrison, Reid R.

    model of this optomotor control system in a standard CMOS VLSI process. The result is a small, low-power is implemented in biological hardware that is many orders of magnitude smaller and more power ef cient than retinotopic array of elementary motion detectors (EMDs), units in the medulla that estimate local motion

  18. Passivation of InGaAs(001)-(2 × 4) by Self-Limiting Chemical Vapor Deposition of a Silicon Hydride Control Layer.

    PubMed

    Edmonds, Mary; Kent, Tyler; Chagarov, Evgueni; Sardashti, Kasra; Droopad, Ravi; Chang, Mei; Kachian, Jessica; Park, Jun Hong; Kummel, Andrew

    2015-07-01

    A saturated Si-Hx seed layer for gate oxide or contact conductor ALD has been deposited via two separate self-limiting and saturating CVD processes on InGaAs(001)-(2 × 4) at substrate temperatures of 250 and 350 °C. For the first self-limiting process, a single silicon precursor, Si3H8, was dosed at a substrate temperature of 250 °C, and XPS results show the deposited silicon hydride layer saturated at about 4 monolayers of silicon coverage with hydrogen termination. STS results show the surface Fermi level remains unpinned following the deposition of the saturated silicon hydride layer, indicating the InGaAs surface dangling bonds are electrically passivated by Si-Hx. For the second self-limiting process, Si2Cl6 was dosed at a substrate temperature of 350 °C, and XPS results show the deposited silicon chloride layer saturated at about 2.5 monolayers of silicon coverage with chlorine termination. Atomic hydrogen produced by a thermal gas cracker was subsequently dosed at 350 °C to remove the Si-Cl termination by replacing with Si-H termination as confirmed by XPS, and STS results confirm the saturated Si-Hx bilayer leaves the InGaAs(001)-(2 × 4) surface Fermi level unpinned. Density function theory modeling of silicon hydride surface passivation shows an Si-Hx monolayer can remove all the dangling bonds and leave a charge balanced surface on InGaAs. PMID:26070022

  19. Effect of sodium ferulate on delayed rectifier K+ currents in PC12 cells

    PubMed Central

    WANG, WEI; WANG, YUYUN; ZHANG, CHUNLEI; SUN, MENGMENG; ZHU, XIAOYIN

    2014-01-01

    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

  20. Power spectrum of the rectified EMG: when and why is rectification beneficial for identifying neural connectivity?

    NASA Astrophysics Data System (ADS)

    Negro, Francesco; Keenan, Kevin; Farina, Dario

    2015-06-01

    Objective. The identification of common oscillatory inputs to motor neurons in the electromyographic (EMG) signal power spectrum is often preceded by EMG rectification for enhancing the low-frequency oscillatory components. However, rectification is a nonlinear operator and its influence on the EMG signal spectrum is not fully understood. In this study, we aim at determining when EMG rectification is beneficial in the study of oscillatory inputs to motor neurons. Approach. We provide a full mathematical description of the power spectrum of the rectified EMG signal and the influence of the average shape of the motor unit action potentials on it. We also provide a validation of these theoretical results with both simulated and experimental EMG signals. Main results. Simulations using an advanced computational model and experimental results demonstrated the accuracy of the theoretical derivations on the effect of rectification on the EMG spectrum. These derivations proved that rectification is beneficial when assessing the strength of low-frequency (delta and alpha bands) common synaptic inputs to the motor neurons, when the duration of the action potentials is short, and when the level of cancellation is relatively low. On the other hand, rectification may distort the estimation of common synaptic inputs when studying higher frequencies (beta and gamma), in a way dependent on the duration of the action potentials, and may introduce peaks in the coherence function that do not correspond to physiological shared inputs. Significance. This study clarifies the conditions when rectifying the surface EMG is appropriate for studying neural connectivity.

  1. Rectifier of aberrant mRNA splicing recovers tRNA modification in familial dysautonomia.

    PubMed

    Yoshida, Mayumi; Kataoka, Naoyuki; Miyauchi, Kenjyo; Ohe, Kenji; Iida, Kei; Yoshida, Suguru; Nojima, Takayuki; Okuno, Yukiko; Onogi, Hiroshi; Usui, Tomomi; Takeuchi, Akihide; Hosoya, Takamitsu; Suzuki, Tsutomu; Hagiwara, Masatoshi

    2015-03-01

    Familial dysautonomia (FD), a hereditary sensory and autonomic neuropathy, is caused by missplicing of exon 20, resulting from an intronic mutation in the inhibitor of kappa light polypeptide gene enhancer in B cells, kinase complex-associated protein (IKBKAP) gene encoding IKK complex-associated protein (IKAP)/elongator protein 1 (ELP1). A newly established splicing reporter assay allowed us to visualize pathogenic splicing in cells and to screen small chemicals for the ability to correct the aberrant splicing of IKBKAP. Using this splicing reporter, we screened our chemical libraries and identified a compound, rectifier of aberrant splicing (RECTAS), that rectifies the aberrant IKBKAP splicing in cells from patients with FD. Here, we found that the levels of modified uridine at the wobble position in cytoplasmic tRNAs are reduced in cells from patients with FD and that treatment with RECTAS increases the expression of IKAP and recovers the tRNA modifications. These findings suggest that the missplicing of IKBKAP results in reduced tRNA modifications in patients with FD and that RECTAS is a promising therapeutic drug candidate for FD. PMID:25675486

  2. Depressive effects of arenobufagin on the delayed rectifier K+ current of guinea-pig cardiac myocytes.

    PubMed

    Cruz, J dos S; Matsuda, H

    1994-02-15

    The effects of a bufadienolide isolated from toad venom, arenobufagin, a potent Na+/K+ pump inhibitor, were studied in single guinea-pig ventricular cells in the whole-cell patch-clamp configuration. Arenobufagin (50 microM) applied extracellularly decreased the amplitude of the delayed rectifier K+ current (IdK) by 30% without affecting the gating kinetics. The L-type Ca2+ current was also depressed, but to a lesser extent. The inward rectifier K+ current was hardly affected. Ouabain and the internal dialysis of cells with the solution containing 20 mM Na+ depressed IdK in a similar way as arenobufagin. On the other hand, arenobufagin also depressed IdK when the Na+/K+ pump was already inhibited in the K(+)-free Tyrode solution. Therefore, both a direct effect on the channel and an indirect effect through the inhibition of the Na+/K+ pump may be involved in the depression of IdK by arenobufagin. PMID:8174614

  3. Tailored Electrical Driving as a Means of Controlling Heat Distribution and Convection Patterns in Joule-Heated Waste Glass Melters

    SciTech Connect

    Fort, James A.; Lessor, Delbert L.

    2004-01-01

    The ability to control melter convection patterns may provide a means of mitigating gas layer buildup under the cold cap, enhancing the heat transfer to the batch, and possible accelerating batch reactions, thereby increasing melt rate and glass throughput. Other operational benefits could result from such control. Convective patterns in an electrically heated melter are dominated by the distribution of Joule heat and thermal boundary conditions for a given melter design and geometry. We believe that control of electrical driving, in particular control of the interaction of electrical fields connected to distinct electrode pairs, can be used to vary the distribution of Joule heat generation. The under-investigated aspect of electrical driving control is the effect of waveform “overlap” of the driving voltages, the “overlap” in the case of harmonic driving being determined by the relative phase. For electrical driving using waveforms chopped by Silicon Controlled Rectifiers (SCRs), the chopping influences the "overlap." This control can provide a means of controlling melt convection. The objective of the present investigation is to test that hypothesis, verifying that such control can be observed for a numerical model of a simple melter geometry.

  4. Immunopathology of intraocular silicone oil: enucleated eyes

    PubMed Central

    Wickham, Louisa; Asaria, Riaz H; Alexander, Robert; Luthert, Phil; Charteris, David G

    2007-01-01

    Aims To characterise the distribution of silicone oil in ocular tissues in globes enucleated after complicated retinal detachment, and to document the distribution and nature of any associated inflammatory response. Method 9 enucleated globes that had previously undergone retinal detachment surgery with silicone oil and 7 control globes that had undergone enucleation after retinal detachment surgery (n?=?2) or ocular trauma (n?=?5) were studied. Sections were histologically examined using light microscopy to document the distribution of silicone oil in ocular tissues. Immunohistochemical analysis was carried out using the ABC technique and a panel of monoclonal and polyclonal antibodies. Electron microscopy was undertaken to observe the penetration of silicone oil in the trabecular meshwork of the anterior chamber drainage angle. Results Silicone oil was distributed throughout the globes—notably in the iris, ciliary body, retina, trabecular meshwork and epiretinal membranes. Focal areas of intraretinal silicone were associated with disorganised retinal architecture, retinectomy sites or subretinal oil. The distribution of macrophages was closely related to the distribution of silicone oil. T and B lymphocytes were not associated with silicone oil unless additional pathology was also present—for example, cyclitic membrane or uveitis. One of the nine eyes had silicone oil present in the optic nerve. In the control globes, the inflammatory response was mediated primarily by macrophages and T lymphocytes, and was less marked than that observed in the silicone oil globes. Conclusion This study shows that silicone oil may be sequestered in varied ocular tissues and is associated with localised inflammation mediated by macrophages. PMID:17005543

  5. Self-rectifying resistive-switching characteristics with ultralow operating currents in SiOxNy/AlN bilayer devices

    NASA Astrophysics Data System (ADS)

    Kwon, Jeong Yong; Park, Ju Hyun; Kim, Tae Geun

    2015-06-01

    We propose a SiOxNy/AlN bilayer resistive switching random access memory scheme to eliminate crosstalk in a crossbar array structure. We demonstrated forming-free self-rectifying behaviors at an ultralow operating current (below 200 nA) by optimizing the current compliance and operating voltage. The set and reset voltages were reduced using a thin AlN layer, and the voltages' on/off ratio and rectifying ratio were as high as 80 and 102, respectively. In addition, the device showed an endurance of 103 dc cycles and a retention time over 105 s.

  6. Silicon Web Process Development

    NASA Technical Reports Server (NTRS)

    Duncan, C. S.; Seidensticker, R. G.; Hopkins, R. H.; Mchugh, J. P.; Hill, F. E.; Heimlich, M. E.; Driggers, J. M.

    1978-01-01

    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.

  7. Proposal of a hybrid rectifier structure with HPF and low THD suitable for front-end trolleybuses systems supplied by AC distribution networks

    Microsoft Academic Search

    Luiz C. G. Freitas; Gustavo B. Lima; Flávio A. S. Gonçalves; Guilherme A. Melo; Carlos A. Canesin

    2009-01-01

    This paper presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements in

  8. Superhard silicon nanospheres

    Microsoft Academic Search

    W. W Gerberich; W. M Mook; C. R Perrey; C. B Carter; M. I Baskes; R Mukherjee; A Gidwani; J Heberlein; P. H McMurry; S. L Girshick

    2003-01-01

    Successful deposition and mechanical probing of nearly spherical, defect-free silicon nanospheres has been accomplished. The results show silicon at this length scale to be up to four times harder than bulk silicon. Detailed measurements of plasticity evolution and the corresponding hardening response in normally brittle silicon is possible in these small volumes. Based upon a proposed length scale related to

  9. Electroluminescing porous silicon device

    Microsoft Academic Search

    John Penczek; Rosemary L. Smith

    1995-01-01

    The main goal was to determine the mechanism of operation of an all silicon, electroluminescing device. The device consists of an n+ silicon 'wire' supported on top of a layer of porous silicon. Other aims included the evaluation of the device's light emitting efficiency and it's potential as a silicon-based light source. The device emits light over a broad spectrum,

  10. Long-term stability of neural prosthetic control signals from silicon cortical arrays in rhesus macaque motor cortex

    NASA Astrophysics Data System (ADS)

    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.

    2011-08-01

    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 require further characterization. Here, we quantify action potential changes and offline neural decoder performance over 382 days of recording from four intracortical arrays in three 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 three animals. During most time periods, decoder performance was not well correlated with action potential amplitude (p > 0.05 for three of four 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.

  11. Point defects in silicon carbide as a promising basis for spectroscopy of single defects with controllable quantum states at room temperature

    NASA Astrophysics Data System (ADS)

    Soltamov, V. A.; Tolmachev, D. O.; Il'in, I. V.; Astakhov, G. V.; Dyakonov, V. V.; Soltamova, A. A.; Baranov, P. G.

    2015-05-01

    The spin and optical properties of silicon vacancy defects in silicon carbide of the hexagonal 6 H polytype have been investigated using photoluminescence, electron paramagnetic resonance, and X-band optically detected magnetic resonance. It has been shown that different configurations of these defects can be used to create an optical alignment of their spin sublevels as in the case of low temperatures and at temperatures close to room temperature ( T = 293 K). The main specific feature of silicon vacancy centers in silicon carbide is that the zero-magnetic-field-splitting parameter of some centers remains constant with variations in the temperature, which indicates prospects for the use of these centers for quantum magnetometry. It has also been shown that a number of centers, on the contrary, are characterized by a strong dependence of the zero-magnetic-field-splitting parameter on the temperature, which indicates prospects for the use of these centers as temperature sensors.

  12. Upgrading Metallurgical-Grade Silicon

    NASA Technical Reports Server (NTRS)

    Woerner, L. M.; Moore, E. B.

    1985-01-01

    Closed-loop process produces semiconductor-grade silicon. Metallurgical-grade silicon converted to ultrapure silicon by reacting with hydrogen and silicon tetrahalide to form trihalosilane, purifying this intermediate and again decomposing to high purity silicon in third stage. Heterogeneously and homogeneously nucleated polycrystalline silicon used in semiconductor device applications and in silicon photovoltaic solar cell fabrication.

  13. Colloidal characterization of silicon nitride and silicon carbide

    NASA Technical Reports Server (NTRS)

    Feke, Donald L.

    1986-01-01

    The colloidal behavior of aqueous ceramic slips strongly affects the forming and sintering behavior and the ultimate mechanical strength of the final ceramic product. The colloidal behavior of these materials, which is dominated by electrical interactions between the particles, is complex due to the strong interaction of the solids with the processing fluids. A surface titration methodology, modified to account for this interaction, was developed and used to provide fundamental insights into the interfacial chemistry of these systems. Various powder pretreatment strategies were explored to differentiate between true surface chemistry and artifacts due to exposure history. The colloidal behavior of both silicon nitride and carbide is dominated by silanol groups on the powder surfaces. However, the colloid chemistry of silicon nitride is apparently influenced by an additional amine group. With the proper powder treatments, silicon nitride and carbide powder can be made to appear colloidally equivalent. The impact of these results on processing control will be discussed.

  14. 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

    Microsoft Academic Search

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

    2009-01-01

    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

  15. 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

    Microsoft Academic Search

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

    2009-01-01

    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

  16. Implementation of a controlled rectifier using AC-AC matrix converter theory

    Microsoft Academic Search

    D. G. Holmes; T.A. Lipo

    1989-01-01

    Current optimum PWM (pulse-width-modulation) strategies are often difficult to physically implement or not easily extended to regenerative operation. The authors propose an alternative PWM strategy based on current AC-AC matrix converter theory, which generates only high-order switching harmonics, presents a unity power factor load to the supply, implicitly extends to regeneration (and operation with a center-tapped DC output), and is

  17. Thin silicon solar cells

    SciTech Connect

    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

    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.

  18. Silicon solar cell process development, fabrication and analysis

    NASA Technical Reports Server (NTRS)

    1978-01-01

    A program plan, baseline process, measurement program and quality control plan were generated. Cutting operations were completed on the silicon sheet material. The first fabrication run of polycrystalline silicon into solar cells by baseline process was completed. Average conversion efficiency for solar cells fabricated by the baseline process from sheet and measured at air mass zero was 10.4%, compared with the control cells, fabricated from single crystal CZ silicon, whose average conversion efficiency was 12.2%.

  19. Thermodynamics of phosphorus in molten silicon

    SciTech Connect

    Miki, Takahirio; Morita, Kazuki; Sano, Nobuo [Univ. of Tokyo (Japan). Dept. of Metallurgy

    1996-12-01

    Removal of phosphorus is one of the major problems on the purification of molten silicon for solar cell. The Gibbs energy change of phosphorus dissolution into molten silicon was determined in the temperature range from 1,723 to 1,848 K by equilibrating a molten silicon-phosphorus alloy in a controlled phosphorus partial pressure and is expressed by the following equations: {1/2}P{sub 2}(g) = {und P} (mass pct, in Si); {Delta}G{degree} = {minus}139,000 ({+-}2,000) + 43.4 ({+-}10.1T)(J/mol). The possibility of removing phosphorus from silicon melts by vacuum treatment and the accompanying yield of silicon during the refining process are discussed.

  20. Precursor flow rate manipulation for the controlled fabrication of twin-free GaAs nanowires on silicon substrates.

    PubMed

    Kang, J H; Gao, Q; Parkinson, P; Joyce, H J; Tan, H H; Kim, Y; Guo, Y; Xu, H; Zou, J; Jagadish, C

    2012-10-19

    Vertically oriented GaAs nanowires (NWs) are grown on Si(111) substrates using metal-organic chemical vapor deposition. Controlled epitaxial growth along the <111> direction is demonstrated following the deposition of thin GaAs buffer layers and the elimination of structural defects, such as twin defects and stacking faults, is found for high growth rates. By systematically manipulating the AsH(3) (group-V) and TMGa (group-III) precursor flow rates, it is found that the TMGa flow rate has the most significant effect on the nanowire quality. After capping the minimal tapering and twin-free GaAs NWs with an AlGaAs shell, long exciton lifetimes (over 700 ps) are obtained for high TMGa flow rate samples. It is observed that the Ga adatom concentration significantly affects the growth of GaAs NWs, with a high concentration and rapid growth leading to desirable characteristics for optoelectronic nanowire device applications including improved morphology, crystal structure and optical performance. PMID:23018759

  1. Laser sintering of silicon powder and carbon nanofibers for porous composite thick films

    NASA Astrophysics Data System (ADS)

    Iwabuchi, Yuki; Yan, Jiwang

    2015-02-01

    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.

  2. Microwave and millimeter-wave rectifying circuit arrays and ultra-wideband antennas for wireless power transmission and communications 

    E-print Network

    Ren, Yu-Jiun

    2009-05-15

    In the future, space solar power transmission and wireless power transmission will play an important role in gathering clean and infinite energy from space. The rectenna, i.e., a rectifying circuit combined with an antenna, is one of the most...

  3. Microwave and millimeter-wave rectifying circuit arrays and ultra-wideband antennas for wireless power transmission and communications

    E-print Network

    Ren, Yu-Jiun

    2009-05-15

    In the future, space solar power transmission and wireless power transmission will play an important role in gathering clean and infinite energy from space. The rectenna, i.e., a rectifying circuit combined with an antenna, is one of the most...

  4. Interleaved Triangular Current Mode (TCM) resonant transition, single phase PFC rectifier with high efficiency and high power density

    Microsoft Academic Search

    C. Marxgut; J. Biela; J. W. Kolar

    2010-01-01

    This paper presents a new topology for a highly compact and highly efficient single-phase Power Factor Corrected (PFC) rectifier system. The new topology consists of several interleaved boost stages which operate in a mode called Triangular Current Mode (TCM) in order to simultaneously achieve a high power density as well as a high efficiency. Applying TCM, ZVS is achieved over

  5. Automotive power generation and control

    Microsoft Academic Search

    David J. Perreault; Vahe Caliskan

    2004-01-01

    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

  6. Ring magnet firing angle control

    Microsoft Academic Search

    M. J. Knott; L. G. Lewis; H. H. Rabe

    1975-01-01

    A device is provided for controlling the firing angles of thyratrons ; (rectifiers) in a ring magnet power supply. A phase lock loop develops a smooth ; ac signal of frequency equal to and in phase with the frequency of the voltage ; wave developed by the main generator of the power supply. A counter that counts ; from zero

  7. Purified silicon production system

    DOEpatents

    Wang, Tihu; Ciszek, Theodore F.

    2004-03-30

    Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.

  8. beta-adrenergic and cholinergic modulation of the inwardly rectifying K+ current in guinea-pig ventricular myocytes.

    PubMed Central

    Koumi, S; Wasserstrom, J A; Ten Eick, R E

    1995-01-01

    1. Whole-cell patch-clamp technique was used to study the beta-adrenergic and cholinergic regulation of the inwardly rectifying K+ conductance (gK1) in isolated guinea-pig ventricular myocytes. 2. In Cl(-)-free solutions or in the presence of 9-anthracenecarboxylic acid or Co2+, bath-applied isoprenaline (Iso) partially inhibited the steady-state whole-cell conductance (gss) calculated from the steady-state current (Iss)-voltage (Iss-V) curve at membrane voltages (Vm) negative to the equilibrium potential for potassium (EK). Iss was also inhibited at Vm positive to EK when the extracellular [K+] was 20 mM. The Iso-sensitive component of gss exhibited the characteristics of the inwardly rectifying K+ conductance (gK1). 3. The Iso-induced inhibition of gK1 was reversible, concentration dependent, blocked by propranolol, mimicked by both forskolin and dibutyryl cAMP, and prevented by including a cAMP-dependent protein kinase (PKA) inhibitor in the pipette solution. These findings suggest that PKA mediates the Iso-induced inhibition of gK1. 4. The apparent dissociation constant (KD) for the concentration dependence of Iso-induced inhibition was 0.035 microM and the Hill coefficient was approximately 1.0. A maximal Iso concentration (1 microM) inhibited gK1 by 40 +/- 4.1% (mean +/- S.E.M.; n = 13). 5. Bath application of acetylcholine (ACh, 0.1 microM or more) antagonized the Iso-induced (1 microM) inhibition of gK1; [ACh] > 1.0 microM antagonized 88 +/- 2.1% (n = 10) of the inhibition. ACh increased the KD for Iso to inhibit Iso-sensitive gK1 and also reduced the maximal Iso-induced inhibition. 6. ACh-induced antagonism could be abolished by pre-incubating myocytes with pertussis toxin (PTX), suggesting that a muscarinic receptor-coupled, PTX-sensitive G protein, Gi, is involved. 7. ACh (10 microM) also antagonized approximately 70% of the dibutyryl cyclic AMP (1 mM)-induced inhibition of gK1 (n = 3), suggesting that the ACh-induced antagonism involves more than simply inhibiting the Iso-mediated activation of adenylyl cyclase via the activated Gi. 8. Intracellularly applied okadaic acid (OkA, 1 microM) did not alter gK1 (control = 134 +/- 5.1 nS vs. OkA = 136 +/- 6.1 nS), but the Iso-induced decrease in gK1 was less (P < 0.001) with OkA present (42.1 +/- 2.4 nS, n = 5) than when absent (54.0 +/- 2.2 nS, n = 10). However, ACh (10 microM) failed to antagonize Iso-induced inhibition with OkA present, suggesting involvement of a protein phosphatase. PMID:7473226

  9. Pre-silicon Post-silicon *Manual functional error correction

    E-print Network

    Markov, Igor

    ! "# "$$% " &'( )( ' ­ ) ) *$+ , ) ( ) )( ) - '$#. / ) ) s ) 0 ( '( (( 12 ) ( Pre-silicon Post-silicon$& & & &$2$&& &22$& + Resynthesize using refined signature %& %' %* !' !& %& %' %* !' !& #12;"2 ! 09

  10. Crowdsourcing Aquatic Resource Data Collection: Exploring Effective Methods to Collect and Rectify Citizen Contributed Data

    NASA Astrophysics Data System (ADS)

    Soderberg, J.

    2011-12-01

    Increasing use of mobile computing and geopositioning technology has provided the environmental sciences with vast new pools of data. Prominent among the gathering methods which produce this data is "crowdsourcing", in which citizen scientists volunteer data. Environmental data collected by crowdsourcing may need to be rectified prior to use by the scientific community. Using mobile applications to educate the crowd, support for the targeted environmental data desired, coupled with thoughtful design of mobile applications can potentially aid the process of rectification. This presentation will outline the use of crowdsourced data, cohort groups and design options for mobile applications that can be used to collect aquatic resource information. If rectification challenges can be overcome, the collective power of the crowd can be harnessed to gather standards-based geographic data, information about environmental conditions, and detailed biological data about aquatic resources. Key Words: Crowdsource, Citizen Scientist, Volunteer Data, Geopositioning Aquatic Resource Geographic Data Author Jon Eric Soderberg

  11. Fast delayed rectifier potassium current is required for circadian neural activity.

    PubMed

    Itri, Jason N; Michel, Stephan; Vansteensel, Mariska J; Meijer, Johanna H; Colwell, Christopher S

    2005-05-01

    In mammals, the precise circadian timing of many biological processes depends on the generation of oscillations in neural activity of pacemaker cells in the suprachiasmatic nucleus (SCN). The ionic mechanisms that underlie these rhythms are largely unknown. Using the mouse brain slice preparation, we show that the magnitude of fast delayed rectifier (FDR) potassium currents has a diurnal rhythm that peaks during the day. Notably, this rhythm continues in constant darkness, providing the first demonstration of the circadian regulation of an intrinsic voltage-gated current in mammalian cells. Blocking this current prevented the daily rhythm in firing rate in SCN neurons. Kv3.1b and Kv3.2 potassium channels were widely distributed within the SCN, with higher expression during the day. We conclude that the FDR is necessary for the circadian modulation of electrical activity in SCN neurons and represents an important part of the ionic basis for the generation of rhythmic output. PMID:15852012

  12. Rectifying Performance and Negative Differential Resistance Behavior of Doping Atoms Effect in Polyphenyls

    NASA Astrophysics Data System (ADS)

    Liu, Wenjiang; Cai, Shaohong; Deng, Xiaoqing

    2015-02-01

    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.

  13. Molecular mechanism underlying ethanol activation of G-protein–gated inwardly rectifying potassium channels

    PubMed Central

    Bodhinathan, Karthik; Slesinger, Paul A.

    2013-01-01

    Alcohol (ethanol) produces a wide range of pharmacological effects on the nervous system through its actions on ion channels. The molecular mechanism underlying ethanol modulation of ion channels is poorly understood. Here we used a unique method of alcohol-tagging to demonstrate that alcohol activation of a G-protein–gated inwardly rectifying potassium (GIRK or Kir3) channel is mediated by a defined alcohol pocket through changes in affinity for the membrane phospholipid signaling molecule phosphatidylinositol 4,5-bisphosphate. Surprisingly, hydrophobicity and size, but not the canonical hydroxyl, were important determinants of alcohol-dependent activation. Altering levels of G protein G?? subunits, conversely, did not affect alcohol-dependent activation, suggesting a fundamental distinction between receptor and alcohol gating of GIRK channels. The chemical properties of the alcohol pocket revealed here might extend to other alcohol-sensitive proteins, revealing a unique protein microdomain for targeting alcohol-selective therapeutics in the treatment of alcoholism and addiction. PMID:24145411

  14. Scanning the Topography of Polyamine Blocker Binding in an Inwardly Rectifying Potassium Channel*

    PubMed Central

    Kurata, Harley T.; Akrouh, Alejandro; Li, Jenny B. W.; Marton, Laurence J.; Nichols, Colin G.

    2013-01-01

    Steeply voltage-dependent inward rectification of Kir (inwardly rectifying potassium) channels arises from blockade by cytoplasmic polyamines. These polycationic blockers traverse a long (>70 ?) pore, displacing multiple permeant ions, en route to a high affinity binding site that remains loosely defined. We have scanned the effects of cysteine modification at multiple pore-lining positions on the blocking properties of a library of polyamine analogs, demonstrating that the effects of cysteine modification are position- and blocker-dependent. Specifically, introduction of positively charged adducts results in two distinct phenotypes: either disruption of blocker binding or generation of a barrier to blocker migration, in a consistent pattern that depends on both the length of the polyamine blocker and the position of the modified cysteine. These findings reveal important details about the chemical basis and specific location of high affinity polyamine binding. PMID:23300089

  15. Study of atrial activities for abnormality detection by phase rectified signal averaging technique.

    PubMed

    Maji, U; Pal, S; Mitra, M

    2015-07-01

    Non-invasive detection of Atrial Fibrillation (AF) and Atrial Flutter (AFL) from ECG at the time of their onset can prevent forthcoming dangers for patients. In most of the previous detection algorithms, one of the steps includes filtering of the signal to remove noise and artefacts present in the signal. In this paper, a method of AF and AFL detection is proposed from ECG without the conventional filtering stage. Here Phase Rectified Signal Average (PRSA) technique is used with a novel optimized windowing method to achieve an averaged signal without quasi-periodicities. Both time domain and statistical features are extracted from a novel SQ concatenated section of the signal for non-linear Support Vector Machine (SVM) based classification. The performance of the proposed algorithm is tested with the MIT-BIH Arrhythmia database and good performance parameters are obtained, as indicated in the result section. PMID:26084877

  16. Activation kinetics of the delayed rectifier potassium current of bullfrog sympathetic neurons.

    PubMed

    Klemic, K G; Durand, D M; Jones, S W

    1998-05-01

    We examined the activation kinetics of the delayed rectifier K+ current of bullfrog sympathetic neurons, primarily using whole cell recording. On depolarization, currents activated with a sigmoid delay but did not show a Cole-Moore shift. The time course of activation differed systematically from an exponential raised to a power. At most voltages, a power of 2 gave the best overall fit but a power of 3 better described the initial delay. After the delay, the time course could be fitted by a single exponential. Time constants were 15-20 ms at 0 mV and decreased to a limiting tau = 7 ms at +50 to +100 mV. Tail currents were well fitted by single exponential functions and accelerated with hyperpolarization, from tau = 15-20 ms at 0 mV to tau = 2 ms at -110 mV (e-fold for 40 mV). Eleven kinetic models were evaluated for their ability to describe the activation kinetics of the delayed rectifier. Hodgkin-Huxley-like models did not fit the data well. A linear model where voltage sensor movement is followed by a distinct channel opening step, allosteric models based on the Monod-Wyman--Changeux model, and an unconstrained C-C-C-O model could describe whole cell data from -100 to +40 mV. After including whole cell data at +60 and +80 mV, and a maximal p(open) of 0.8 from noise analysis of cell-attached patches, an allosteric model fit the data best, as the other models had difficulty describing qualitative features of the data. However, some more complex schemes (with additional free parameters) cannot be excluded. We propose the allosteric model as an empirical description of macroscopic ionic currents, and as a model worth considering in future studies on the molecular mechanism of potassium channel gating. PMID:9582210

  17. Asymmetrical contributions of subunit pore regions to ion selectivity in an inward rectifier K+ channel.

    PubMed Central

    Silverman, S K; Lester, H A; Dougherty, D A

    1998-01-01

    We have investigated aspects of ion selectivity in K+ channels by functional expression of wild-type and mutant heteromultimeric G protein-coupled inward-rectifier K+ (GIRK) channels in Xenopus oocytes. Within the K+ channel pore (P) region signature sequence, a large number of point mutations in GIRK1 and GIRK4 subunits have been made at a key tyrosine residue--the "signature" tyrosine of the GYG. Studies of mutant GIRK1/GIRK4 heteromultimers reveal that the GIRK1 and GIRK4 subunits contribute asymmetrically to K+ selectivity. The signature tyrosine of GIRK1 can be mutated to many different residues while retaining selectivity; in contrast, the analogous position in GIRK4 must be tyrosine for maximum selectivity. Other residues of the P region also contribute to selectivity, and studies with GIRK1/GIRK4 chimeras reveal that an intact, heteromultimeric P region is necessary and sufficient for optimal K+ selectivity. We propose that the GIRK1 and GIRK4 P regions play roles similar to the two P regions of an emerging family of K+ channels whose subunits each have two P regions connected in tandem. We find different consequences between similar mutations in inward-rectifier and voltage-gated K+ channels, which suggests that the pore structures and selectivity mechanisms in the two classes of channel may not be identical. We confirm that GIRK4 subunits alone can form functional channels in oocytes, but we find that these channels are measurably permeable to Na2+ and Ca2+. PMID:9726934

  18. An inwardly rectifying potassium channel in apical membrane of Calu-3 cells.

    PubMed

    Wu, Jin V; Krouse, Mauri E; Rustagi, Arjun; Joo, Nam Soo; Wine, Jeffrey J

    2004-11-01

    Patch clamp methods and reverse transcription-polymerase chain reaction (RT-PCR) were used to characterize an apical K+ channel in Calu-3 cells, a widely used model of human airway gland serous cells. In cell-attached and excised apical membrane patches, we found an inwardly rectifying K+ channel (Kir). The permeability ratio was PNa/PK = 0.058. In 30 patches with both cystic fibrosis transmembrane conductance regulator and Kir present, we observed 79 cystic fibrosis transmembrane conductance regulator and 58 Kir channels. The average chord conductance was 24.4 +/- 0.5 pS (n = 11), between 0 and -200 mV, and was 9.6 +/- 0.7 pS (n = 8), between 0 and 50 mV; these magnitudes and their ratio of approximately 2.5 are most similar to values for rectifying K+ channels of the Kir4.x subfamilies. We attempted to amplify transcripts for Kir4.1, Kir4.2, and Kir5.1; of these only Kir4.2 was present in Calu-3 lysates. The channel was only weakly activated by ATP and was relatively insensitive to internal pH. External Cs+ and Ba2+ blocked the channel with Kd values in the millimolar range. Quantitative modeling of Cl- secreting epithelia suggests that secretion rates will be highest and luminal K+ will rise to 16-28 mm if 11-25% of the total cellular K+ conductance is placed in the apical membrane (Cook, D. I., and Young, J. A. (1989) J. Membr. Biol. 110, 139-146). Thus, we hypothesize that the K+ channel described here optimizes the rate of secretion and is involved in K+ recycling for the recently proposed apical H+ -K+ -ATPase in Calu-3 cells. PMID:15328350

  19. Formation of iron disilicide on amorphous silicon

    NASA Astrophysics Data System (ADS)

    Erlesand, U.; Östling, M.; Bodén, K.

    1991-11-01

    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 525°C. 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 525-625°C was studied by RBS and the activation energy was found to be 1.5 ± 0.1 eV.

  20. A nanocomposite ultraviolet photodetector based on interfacial trap-controlled charge injection

    NASA Astrophysics Data System (ADS)

    Guo, Fawen; Yang, Bin; Yuan, Yongbo; Xiao, Zhengguo; Dong, Qingfeng; Bi, Yu; Huang, Jinsong

    2012-12-01

    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 (<0.2 A W-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 (~721-1,001 A W-1). Under a bias of <10 V, our device provides a detectivity of 3.4 × 1015 Jones at 360 nm at room temperature, which is two to three orders of magnitude higher than that of existing inorganic semiconductor ultraviolet photodetectors.

  1. A nanocomposite ultraviolet photodetector based on interfacial trap-controlled charge injection.

    PubMed

    Guo, Fawen; Yang, Bin; Yuan, Yongbo; Xiao, Zhengguo; Dong, Qingfeng; Bi, Yu; Huang, Jinsong

    2012-12-01

    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 (<0.2 A W(-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 (?721-1,001 A W(-1)). Under a bias of <10 V, our device provides a detectivity of 3.4 × 10(15) Jones at 360 nm at room temperature, which is two to three orders of magnitude higher than that of existing inorganic semiconductor ultraviolet photodetectors. PMID:23142945

  2. Use of Silicon Detectors in Medical Physics

    NASA Astrophysics Data System (ADS)

    Montaño Zetina, Luis Manuel

    2006-09-01

    In this document I will review the characteristics and applications of silicon detectors in Medical Physics. I will cover the activities done by some research mexican groups working with silicon detectors (Silicon Strip and PIN detectors) as devices for digital imaging supported by some Monte Carlo simulations and X-ray units parameters valuation devices for quality control. In the end I will give some perspectives on the future of these scientific activities as important contributions in the development of the area of Medical Physics around the world.

  3. Removing Undesired Fine Powder From Silicon Reactor

    NASA Technical Reports Server (NTRS)

    Flagella, Robert N.

    1992-01-01

    Fluidized-bed reactor produces highly pure polycrystalline silicon particles with diameters approximately greater than 400 micrometers. Operates by pyrolysis of silane in reaction zone, which is bed of silicon seed particles fluidized by flow of silane and carrier gas. Above reaction zone, gas mixture flows rapidly enough to entrain silicon powders, but not larger seed and product particles. Entrained particles swept out of reactor. Applicable to other processes such as production of fine metal and ceramic powders where control of sizes of product needed.

  4. Thermodynamics of phosphorus in molten silicon

    Microsoft Academic Search

    Takahirio Miki; Kazuki Morita; Nobuo Sano

    1996-01-01

    Removal of phosphorus is one of the major problems on the purification of molten silicon for solar cell. The Gibbs energy\\u000a change of phosphorus dissolution into molten silicon was determined in the temperature range from 1723 to 1848 K by equilibrating\\u000a a molten silicon-phosphorus alloy in a controlled phosphorus partial pressure and is expressed by the following equations.\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a $$\\\\begin{gathered} \\\\frac{1}{2}P_2

  5. Bond Testing for Effects of Silicone Contamination

    NASA Technical Reports Server (NTRS)

    Plaia, James; Evans, Kurt

    2005-01-01

    In 2003 ATK Thiokol discovered that the smocks and coveralls worn by its operations personnel for safety and contamination control were themselves contaminated with a silicone defoamer and a silicone oil. As a growing list of items have been identified as having this form of contamination, it was desirable to devise a test method to determine if the contamination level detected could cause subsequent processing concerns. The smocks and coveralls could potentially contact bonding surfaces during processing so the test method focused on dry transfer of the silicone from the clothing to the bonding surface.

  6. Use of Silicon Detectors in Medical Physics

    SciTech Connect

    Montano Zetina, Luis Manuel [Physics Department, Cinvestav, Mexico City (Mexico)

    2006-09-25

    In this document I will review the characteristics and applications of silicon detectors in Medical Physics. I will cover the activities done by some research mexican groups working with silicon detectors (Silicon Strip and PIN detectors) as devices for digital imaging supported by some Monte Carlo simulations and X-ray units parameters valuation devices for quality control. In the end I will give some perspectives on the future of these scientific activities as important contributions in the development of the area of Medical Physics around the world.

  7. Affordable Fabrication and Properties of Silicon Carbide-Based Interpenetrating Phase Composites

    NASA Technical Reports Server (NTRS)

    Singh, Mrityunjay

    1998-01-01

    An affordable processing technique for the fabrication of silicon carbide-based interpenetrating phase composites (IPCs) is presented. This process consists of the production of microporous carbon preforms and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture for which methods to control pore volume and pore size have been established. The process gives good control of microstructure and morphology of silicon carbide-based composite materials. Room and high temperature mechanical properties (flexural strength, compressive strength, and flexural creep) of low and high silicon-silicon carbide composites will be discussed.

  8. Fabrication and Performance of Silicon-Embedded Permanent-Magnet Microgenerators

    E-print Network

    Herrault, Florian

    This paper focuses on the design, fabrication, and characterization of silicon-packaged permanent-magnet (PM) microgenerators. The use of silicon packaging favors fine control on shape and dimensions in batch fabrication ...

  9. Advanced silicon photonic modulators

    E-print Network

    Sorace, Cheryl M

    2010-01-01

    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 ...

  10. The Silicon Cochlea:. from Biology to Bionics

    Microsoft Academic Search

    L. Turicchia; R. Sarpeshkar

    2003-01-01

    The silicon cochlea maps the traveling-wave architecture of the biological cochlea into a silicon chip. Such an architecture is an efficient way of implementing a bank of wide-dynamic-range frequency-analysis channels in both biology and electronics [1]. However, in both biology and electronics, gain control is essential in ensuring that the architecture is robust to parameter changes, and in attaining wide

  11. Photocurrent spectrum measurements of doped black silicon

    Microsoft Academic Search

    S. K. Zhang; H. Ahmar; B. Chen; W. Wang; R. Alfano

    2011-01-01

    Photocurrent spectra of doped black silicon (BSi) samples were investigated using metal-semiconductor-metal (MSM) structure. The BSi samples were fabricated through femtosecond-laser doping method. Two pieces of samples were annealed in nitrogen ambient for 30 minutes at different temperatures 350°C and 700°C. One control sample remains without annealing. It was found that the doped black silicon samples have an electron mobility

  12. Magnetic and electric hotspots with silicon nanodimers.

    PubMed

    Bakker, Reuben M; Permyakov, Dmitry; Yu, Ye Feng; Markovich, Dmitry; Paniagua-Domínguez, Ramón; Gonzaga, Leonard; Samusev, Anton; Kivshar, Yuri; Luk'yanchuk, Boris; Kuznetsov, Arseniy I

    2015-03-11

    The study of the resonant behavior of silicon nanostructures provides a new route for achieving efficient control of both electric and magnetic components of light. We demonstrate experimentally and numerically that enhancement of localized electric and magnetic fields can be achieved in a silicon nanodimer. For the first time, we experimentally observe hotspots of the magnetic field at visible wavelengths for light polarized across the nanodimer's primary axis, using near-field scanning optical microscopy. PMID:25686205

  13. Silicon-based optoelectronics

    Microsoft Academic Search

    R. A. Soref

    1993-01-01

    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

  14. Bonding silicones with epoxies

    SciTech Connect

    Tira, J.S.

    1980-01-01

    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.

  15. 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.

  16. Process for producing silicon

    DOEpatents

    Olson, Jerry M. (Lakewood, CO); Carleton, Karen L. (Boulder, CO)

    1984-01-01

    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.

  17. 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.

  18. SILICON PHOTONICS Signal regeneration

    E-print Network

    Braun, Paul

    SILICON PHOTONICS Signal regeneration SPECTROSCOPY Real-time Raman BIOLUMINESCENCE Firefly and waveguides in three-dimensional silicon photonic crystals STEPHANIE A. RINNE, FLORENCIO GARCI of unprecedented quality within silicon inverse opals. High-resolution three-dimensional features are first formed

  19. Luminescence of black silicon

    Microsoft Academic Search

    Ali Serpengüzel; Adnan Kurt; Ibrahim Inanç; James E. Cary; Eric Mazur

    2008-01-01

    Room temperature visible and near-infrared photoluminescence from black silicon has been observed. The black silicon is manufactured by shining femtosecond laser pulses on silicon wafers in air, which were later annealed in vacuum. The photoluminescence is quenched above 120 K due to thermalization and competing nonradiative recombination of the carriers. The photoluminescence intensity at 10K depends sublinearly on the excitation

  20. Bonding silicones with epoxies

    Microsoft Academic Search

    Tira

    1980-01-01

    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