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1

Effects of 22 MeV protons on single junction and silicon controlled rectifiers  

NASA Technical Reports Server (NTRS)

The effects of 22-MeV protons on various types of silicon single junction and silicon controlled rectifiers were investigated. The results show that low-leakage devices and silicon controlled rectifiers are the most susceptable to radiation damage. There are also differences noted between single junction rectifiers of the same type made by different manufacturers, which emphasizes the need for better selection of devices used in spacecraft.

Beatty, M. E., III

1972-01-01

2

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

NASA Technical Reports Server (NTRS)

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

Gourash, F.

1984-01-01

3

N-Type Extended Drain Silicon Controlled Rectifier Electrostatic Discharge Protection Device for High-Voltage Operating Input/Output Applications  

NASA Astrophysics Data System (ADS)

An electrostatic discharge (ESD) protection device, the so-called N-type extended drain silicon controlled rectifier (NEDSCR) device, was analyzed for high-voltage input/output (I/O) applications. A conventional NEDSCR device shows typical silicon controlled rectifier (SCR)-like characteristics with a high current immunity level. However, its extremely low snapback holding voltage and low on-resistance cause a linearity problem in the current immunity level, which obstructs adopting this device as an ESD protection device. Moreover, it may cause a latch-up problem during a normal operation. Our simulation analysis results that these disadvantageous NEDSCR device characteristics are cured by appropriate junction/channel engineering. Adding a P-type counter pocket source (CPS) implant enclosing source N+ diffusion is proven to increase the snapback holding voltage and on-resistance of the NEDSCR device, realizing an excellent ESD protection performance and a high latch-up immunity. Since the CPS implant technique does not change avalanche breakdown voltage, this methodology does not reduce available operation voltage and is applicable regardless of the operation voltage.

Seo, Yong-Jin; Kim, Kil-Ho

2007-04-01

4

Reliable Breakdown Obtained in Silicon Carbide Rectifiers  

NASA Technical Reports Server (NTRS)

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

Neudeck, Philip G.

1997-01-01

5

Silicon Carbide High-Temperature Power Rectifiers Fabricated and Characterized  

NASA Technical Reports Server (NTRS)

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

1996-01-01

6

Temperature-gated thermal rectifier for active heat flow control.  

PubMed

Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (<1%). To the best of our knowledge, this is the first demonstration of solid-state active-thermal devices with a large rectification in the Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage. PMID:25010206

Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

2014-08-13

7

Modelling a single phase voltage controlled rectifier using Laplace transforms  

NASA Technical Reports Server (NTRS)

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

Kraft, L. Alan; Kankam, M. David

1992-01-01

8

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

Microsoft Academic Search

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

John C. Salmon

1993-01-01

9

Unity Power Factor Control for Three-Phase Three-Level Rectifiers Without Current Sensors  

Microsoft Academic Search

Three-level rectifiers with reduced number of switches (such as the Vienna rectifier) to improve the input power quality of rectifier systems have been receiving wide interest in the past years. In this paper, a new carrier-based pulsewidth-modulation control algorithm is proposed for such converters to eliminate the low-frequency harmonics in the line current while achieving unity power factor at the

Bingsen Wang; Giri Venkataramanan; Ashish Bendre

2007-01-01

10

A novel control of three-phase PWM rectifier using single current sensor  

Microsoft Academic Search

This paper proposes a control method for a three-phase PWM rectifier using only a single current sensor in the DC link. A PWM modulation strategy for reconstructing three phase currents from the DC link current is given. The states of the rectifier switch are modified so that all phase currents can be reconstructed in a switching period although active vectors

Woo-Cheol Lee; Taeg-Joon Kweon; Dong-Seok Hyun; Taeck-Kie Lee

1999-01-01

11

Series and parallel operation of hysteresis current-controlled PWM rectifiers  

Microsoft Academic Search

Different strategies for series and parallel connections of hysteresis current-controlled PWM rectifier have been investigated by experiments, computer simulations, and analyses. Each rectifier unit delivers near-sinusoidal current waveforms at unity (or even leading) power factor. Of particular concern are the questions of: (i) system stability; (ii) the capability of the modular units to share voltage (series connection) and current (parallel

J. W. Dixon; B. T. Ooi

1989-01-01

12

A novel control method for three-phase PWM rectifiers using a single current sensor  

Microsoft Academic Search

This paper proposes a control method for three-phase voltage-source PWM rectifiers using only a single current sensor in the DC-link. A PWM modulation strategy for reconstructing three phase currents from the DC-link current is given. When 3? input currents cannot be reconstructed, a method for modifying the switching state of the PWM rectifier and a method for the predictive state

Woo-Cheol Lee; Dong-Seok Hyun; Taeck-Kie Lee

2000-01-01

13

Control of zero-sequence current in parallel connected voltage source PWM rectifiers using converter-flux-based control  

Microsoft Academic Search

A new zero vector selection strategy for the converter flux based control (CFC) of voltage source PWM rectifiers is introduced. With this strategy the circulating current in paralleled rectifiers is effectively suppressed and independent operations of the individual converter units are achieved. In addition to normal line filter, no additional passive components such as transformers or current sharing reactors are

R. Pollanen; A. Tarkiainen; M. Niemela; J. Pyrhonen

2005-01-01

14

Voltage and frequency control of SG based wind farms with uncontrolled HVDC rectifier  

Microsoft Academic Search

The present paper introduces the study and validation of a voltage and frequency control technique of Synchronous Generator based off-shore wind farms connected with a line commutated HVDC link with an uncontrolled rectifier. The proposed control technique is based on the use of standard practice current control for the wind turbines and outer, slower loops for voltage and frequency control.

R. Blasco-Gimenez; S. Año?-Villalba; J. Rodri?guez-D'derle?e; F. Morant; S. Bernal

2010-01-01

15

Comparison of gold, platinum, and electron irradiation for controlling lifetime in power rectifiers  

Microsoft Academic Search

Recombination statistics based upon a single dominant level have been used to predict the relative characteristics of gold-diffused, platinum-diffused, and electron-irradiated silicon power rectifiers and thyristors. These calculations indicate that gold-diffused devices will have the best trade-off curve between forward voltage drop and reverse recovery time, while exhibiting the highest leakage currents. Electron-irradiated devices are predicted to have the worst

B. J. Baliga; E. Sun

1977-01-01

16

Temperature-Gated Thermal Rectifier for Active Heat Flow Control Kedar Hippalgaonkar,,  

E-print Network

conversion. Like electronic devices developed for the control of electric power, it is very desirableTemperature-Gated Thermal Rectifier for Active Heat Flow Control Jia Zhu,, Kedar Hippalgaonkar, University of California at Berkeley, Berkeley, California 94720, United States § Department of Physics

Wu, Junqiao

17

NONLINEAR-CARRIER CONTROL FOR HIGH-POWER-FACTOR RECTIFIERS BASED ON  

E-print Network

/divider circuitry in the voltage feedback loop are eliminated. The simple. high-performance controller is well, flyback, Cuk and Sepic converters offer the benefits of single-stage transformer isolation, voltage stepNONLINEAR-CARRIER CONTROL FOR HIGH-POWER-FACTOR RECTIFIERS BASED ON FLYBACK, @UK OR SEPIC

18

A hybrid structure using phase-controlled rectifiers and high-frequency converters for magnet-load power supplies  

Microsoft Academic Search

Thyristor rectifiers are still the preferred choice for large magnet power supplies. However, large harmonic voltages, resulting in large current ripple, and slow dynamic response are major drawbacks of these converters. This paper presents a topology and a control technique for hybrid large-power high-precision magnet power supplies. The system consists of a phase controlled rectifier connected in series with a

H. Jin; Y. Wang; G. Joos

1996-01-01

19

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

Microsoft Academic Search

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

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

1997-01-01

20

Power regenerative controls by utilizing thyristor rectifier of voltage source inverter  

Microsoft Academic Search

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

Keiju Matsui; Kazuo Tsuboi; Saburo Muto

1992-01-01

21

IDA-PBC controller for a bidirectional power flow full-bridge rectifier* Carles Batlle  

E-print Network

IDA-PBC controller for a bidirectional power flow full-bridge rectifier* Carles Batlle MAIV, EPSEVG and IOC, Univ. Polit`ecnica de Catalunya 08800 Vilanova i la G., Spain carles.batlle@upc.edu Arnau D-34166. Further information is available at http://www.geoplex.cc. Carles Batlle and Enric Fossas have been

Batlle, Carles

22

Simplified predictive current controller for bidirectional voltage source PWM rectifier based on state feedback decoupling  

Microsoft Academic Search

A simplified predictive current controller for the three-phase bidirectional voltage source PWM rectifier is proposed. Firstly, the mathematic model in synchronous d-q coordinate is founded in the discrete-time domain. Then the simplified predictive current controller with state feedback decoupling is designed and analyzed. To overcome the drawbacks of the conventional predictive current controller and improve the control system dynamics, the

Jin Wang; Libing Zhou; Jing Shi

2008-01-01

23

Transistor as a Rectifier  

E-print Network

Transistor is a three terminal semiconductor device normally used as an amplifier or as a switch. Here the alternating current (a.c) rectifying property of the transistor is considered. The ordinary silicon diode exhibits a voltage drop of ~0.6V across its terminals. In this article it is shown that the transistor can be used to build a diode or rectify low current a.c (~mA) with a voltage drop of ~0.03V. This voltage is ~20 times smaller than the silicon diode. This article gives the half-wave and full-wave transistor rectifier configurations along with some applications to justify their usefulness.

Baddi, Raju

2012-01-01

24

Transistor as a Rectifier  

E-print Network

Transistor is a three terminal semiconductor device normally used as an amplifier or as a switch. Here the alternating current (a.c) rectifying property of the transistor is considered. The ordinary silicon diode exhibits a voltage drop of ~0.6V across its terminals. In this article it is shown that the transistor can be used to build a diode or rectify low current a.c (~mA) with a voltage drop of ~0.03V. This voltage is ~20 times smaller than the silicon diode. This article gives the half-wave and full-wave transistor rectifier configurations along with some applications to justify their usefulness.

Raju Baddi

2013-04-20

25

Average Current Mode Control of Three-Phase Boost Rectifiers with Low Harmonic Distortion Applied to Small Wind Turbines  

Microsoft Academic Search

This paper presents the application of average current mode control to reduce the THDi and increase the PF in a three-phase boost rectifier driving a small wind turbine. It is used as the input stage of small wind turbines with permanent magnet synchronous generators operating at variable speed.The boost rectifier output is connected to an inverter which injects the energy

O. C. Castillo; E. F. Amoros; G. G. Sanfeliu; L. Morales

2009-01-01

26

A combined approach using phase-controlled rectifiers and high-frequency converters for magnet-load power supplies  

Microsoft Academic Search

In this paper, a control technique for a hybrid large-power high-precision magnet power supply is presented. The system consists of a phase controlled rectifier and a high-frequency PWM converter. The rectifier is designed to handle the main output power and the PWM converter is designed only for harmonics cancellation and error compensation. A feedforward control scheme is proposed to ensure

H. Jin; Y. Wang; G. Joos

1994-01-01

27

A new control strategy for voltage-type PWM rectifiers to realize zero steady-state control error in input current  

Microsoft Academic Search

In this paper, a new simple control strategy for AC input current of voltage-type pulsewidth modulation (PWM) rectifiers which can eliminate the steady-state control error completely is proposed. This control method requires neither the instantaneous value of the supply voltage nor any accurate circuit parameters on the AC side of the rectifier. Thus, a robust operation against the variation of

Yukihiko Sato; Tomotsugu Ishizuka; Kazuyoshi Nezu; Teruo Kataoka

1998-01-01

28

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...

29

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

PubMed Central

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

Lee, Hyung-Min; Ghovanloo, Maysam

2011-01-01

30

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

31

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

Microsoft Academic Search

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

K. Matsui; U. Mizuno; Y. Murai

1992-01-01

32

Combinational logic for generating gate drive signals for phase control rectifiers  

NASA Astrophysics Data System (ADS)

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.

Dolland, C. R.; Trimble, D. W.

1982-09-01

33

Controllable step motors and rectifiers of magnetic flux quanta using periodic arrays of asymmetric pinning defects  

NASA Astrophysics Data System (ADS)

We study the transport of vortices in superconductors with regular arrays of asymmetric pinning wells when applying an alternating electrical current. The asymmetric traps are modelled by the superposition of two interpenetrating square lattices of weak and strong pinning centers with separation smaller than the lattice constant. We show that this system can induce a net rectifying or diode effect for the vortex motion, including collective step-motor-type dynamics, where many vortices move forward a controlled and exact number of pin-lattice spacings at each cycle of the ac driving force. This system exhibits a remarkable net dc response with striking sawtooth-type oscillations. The net dc voltage response Vdc of the ac-driven vortices versus both the half period P and the amplitude FL of the “square wave” ac drive has been detailed in the present work. The influence of the equilibrium thermal noise, the shift between the two pinning sublattices, the degree of translational and orientational disorder, and the size of the simulation system on the Vdc response of the vortex motion at ac drive has also been addressed. Devil staircase and Arnold’s tongue structures are revealed. We also analytically derive all the key features of our numerical results. This system provides a very controllable stepmotor for the control of collective motion. Our results apply mutatis mutandis to arrays of Josephson junctions, colloidal systems with optical traps, Wigner crystals, and any system with repelling movable objects that can be pinned by a lattice of traps.

Zhu, B. Y.; Marchesoni, F.; Moshchalkov, V. V.; Nori, Franco

2003-07-01

34

Simple direct power control of three-phase PWM rectifier using space-vector modulation (DPC-SVM)  

Microsoft Academic Search

This paper proposes a novel and simple direct power control of three-phase pulsewidth-modulated (PWM) rectifiers with constant switching frequency using space-vector modulation (DPC-SVM). The active and reactive powers are used as the pulse width modulated (PWM) control variables instead of the three-phase line currents being used. Moreover, line voltage sensors are replaced by a virtual flux estimator. The theoretical principle

Mariusz Malinowski; M. Jasinski; M. P. Kazmierkowski

2004-01-01

35

An Output-Power-Control Strategy for a Three-Phase PWM Rectifier Under Unbalanced Supply Conditions  

Microsoft Academic Search

Instantaneous power regulation is an effective way to improve the performance of a pulsewidth-modulation rectifier operating under unbalanced supply-voltage conditions. By properly setting current commands, this approach aims to achieve performance features that are normally achievable only under ideal balanced operating conditions. This paper proposes an instantaneous power-regulation strategy called output-power-control method, in which the current commands are determined so

Bo Yin; Ramesh Oruganti; Sanjib Kumar Panda; Ashoka K. S. Bhat

2008-01-01

36

Transformer-rectifier flux pump using inductive current transfer and thermally controlled Nb3Sn cryotrons  

Microsoft Academic Search

Transformer-rectifier flux pumps using thermally switched Nb3Sn cryotrons are being investigated as a loss make-up device for the proposed isochorically operated (sealed) superconducting magnets for the Canadian Maglev vehicle. High currents (1000 A) were obtained in an experimental flux pump using inductive current transfer and operating at 2 Hz.

D. L. Atherton; R. Davies

1979-01-01

37

Rectifier cabinet static breaker  

DOEpatents

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

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

1992-09-01

38

Frequency domain analysis and evaluation of differential mode input current for three-phase DCM boost rectifiers with different control strategies  

Microsoft Academic Search

By using frequency domain analysis, it is possible to predict the low and high frequency harmonics of the differential mode input current of three-phase DCM boost rectifiers. This analysis is applied to three different modulation strategies, which are the constant duty-cycle control, the harmonic injection method and the variable switching frequency control. The results can be used to design the

J. C. Crebier; P. Barbosa; F. Canales; F. C. Lee; J. P. Ferrieux

2000-01-01

39

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.

40

Research on two space vector current control strategies for three phase voltage source PWM rectifier  

Microsoft Academic Search

In this paper, to improve the control speed of three phase PWM VSI's ac-side current, two space vector current control strategies are proposed respectively named current- space-vector hysteresis control based on projection method and optimized current-space-vector control. The current- space-vector hysteresis control based on projection method is to find a switch state in real time based on the electric variables

Zhang Xiang; Ma Kun; Li Ning

2011-01-01

41

Inwardly rectifying Kir2.1 currents in human ?-cells control electrical activity: Characterisation and mathematical modelling.  

PubMed

Pancreatic ?-cells fire action potentials as do cardiac cells and neurons, and electrical activity plays a central role in glucose-stimulated insulin secretion, which is disturbed in diabetes. The inwardly rectifying Kir2.1 potassium channels (KCNJ2 gene) control cardiac electrical activity by stabilising the interspike interval. Loss-of-function abnormalities in cardiac Kir2.1 currents can lead to the long QT syndrome and alterations of cardiac excitability, and patients with some forms of long QT syndrome suffer from over-secretion of insulin, hyperinsulinemia and symptomatic hypoglycemia. The KCNJ2 gene is also expressed in human pancreatic islets, and we show that functional Kir2.1 currents are present in human ?-cells. We characterised the human Kir2.1 ?-cell current, and included it in a recent mathematical model of electrical activity in human ?-cells. Based on our simulations we propose that Kir2.1 currents control the interspike interval, and predict that blocking Kir2.1 channels increases the action potential frequency, which should augment the rate of insulin secretion. Vice versa, the model suggests that hyperactive Kir2.1 channels may lead to reduced insulin secretion. Our findings provide a putative link between increased insulin secretion and the long QT syndrome, and give novel insight into normal and disturbed ?-cell function. PMID:25727015

Riz, Michela; Braun, Matthias; Wu, Xichen; Pedersen, Morten Gram

2015-04-01

42

A hybrid passivity based controller design for a three phase voltage source reversible boost type rectifier  

Microsoft Academic Search

We present a criteria to design the switching control sequence for a nonlinear system in a normal form when the control input exists in a finite set. The criteria is based on the minimization of a Lyapunov function and the concept of output regulated subspaces presented by Ludvingsen et al. (1998). Moreover, we propose to modify the controller by adding

G. Escobar; R. Ortega; H. Sira-Ramfrez; H. Ludvigsen

1998-01-01

43

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

E-print Network

: {matherb, maksimov} @colorado.edu Abstract- Accurate input power measurements for off-line power supplies to calculate the input power has already been sensed as digital control data. This paper investigates input power measurement techniques that use data already available from the digital PFC controller

44

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

E-print Network

, and a firing current pulse iG is applied to the gate terminal. Delaying the firing pulse by an angle does the control of the load voltage. The firing angle is measured from the crossing point between the phase

Catholic University of Chile (Universidad Católica de Chile)

45

A Mixed-SignalASIC Power-Factor-Correction(PFC) Controller for High Frequency Switching Rectifiers  

E-print Network

have been successful at meeting the demands of many systems over the past ten years, especiallyusing Science Foun- dation under Grant No. ECS-9703449 and by the University of Colorado 1998 Summer Session-3-2 can often be met using simple controller/power stage configura- tions without precise input current

46

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

NASA Technical Reports Server (NTRS)

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

Birchenough, A. G.

1971-01-01

47

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

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

48

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

PubMed Central

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

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

2014-01-01

49

Vascular inward rectifier k(+) channels as external k(+) sensors in the control of cerebral blood flow.  

PubMed

For decades it has been known that external K(+) ions are rapid and potent vasodilators that increase CBF. Recent studies have implicated the local release of K(+) from astrocytic endfeet-which encase the entirety of the parenchymal vasculature-in the dynamic regulation of local CBF during NVC. It has been proposed that the activation of KIR channels in the vascular wall by external K(+) is a central component of these hyperemic responses; however, a number of significant gaps in our knowledge remain. Here, we explore the concept that vascular KIR channels are the major extracellular K(+) sensors in the control of CBF. We propose that K(+) is an ideal mediator of NVC, and discuss KIR channels as effectors that produce rapid hyperpolarization and robust vasodilation of cerebral arterioles. We provide evidence that KIR channels, of the KIR 2 subtype in particular, are present in both the endothelial and SM cells of parenchymal arterioles and propose that this dual positioning of KIR 2 channels increases the robustness of the vasodilation to external K(+) , enables the endothelium to be actively engaged in NVC, and permits electrical signaling through the endothelial syncytium to promote upstream vasodilation to modulate CBF. PMID:25641345

Longden, Thomas A; Nelson, Mark T

2015-04-01

50

Noise Properties of Rectifying Nanopores  

SciTech Connect

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

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

2011-02-18

51

Noise Properties of Rectifying Nanopore  

SciTech Connect

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

Vlassiouk, Ivan V [ORNL

2011-01-01

52

Curvature Control of Silicon Microlens for THz Dielectric Antenna  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

53

Control of silicon nanoparticle size embedded in silicon oxynitride dielectric matrix  

SciTech Connect

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

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

2013-07-21

54

A new input-voltage feedforward harmonic-injection technique with nonlinear gain control for single-switch, three-phase, DCM boost rectifiers  

Microsoft Academic Search

A new input-voltage feedforward harmonic-injection technique for a single-switch, three-phase, discontinuous-conduction-mode boost rectifier is introduced. With this technique, rectification with a low total harmonic distortion that meets the IEC555-2 requirements can be achieved. In addition, the rectifier shows an excellent transient performance which dramatically reduces the rectifier's output voltage overshoots during line-voltage step-up transients. Moreover, by the addition of a

Yungtaek Jang; Milan M. Jovanovic

2000-01-01

55

Diodes and Rectifiers  

NSDL National Science Digital Library

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

Kuphaldt, Tony R.

56

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

PubMed

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

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

2014-04-01

57

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

Microsoft Academic Search

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

Mohammad Ali Rezaei; Shahrokh Farhangi; Hossein Iman-Eini

2010-01-01

58

DIGITAL SIMULATION OF A RECTIFIER LOADED SYNCHRONOUS MACHINE  

Microsoft Academic Search

The digital computer simulation of a rectifier loaded synchronous generator is described in this paper. The digital model of the synchronous generator with either a controlled or uncontrolled rectifier bridge deals efficiently with the complex commutation conditions when the source impedance is significant. From the equations developed in this paper, the performance of synchronous generators with or without damper windings,

P. K. DASH; R. W. MENZIES; R. M. MATHUR

1977-01-01

59

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.

60

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

Microsoft Academic Search

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

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

2003-01-01

61

Unimolecular electronic rectifiers  

NASA Astrophysics Data System (ADS)

The fabrication of a unimolecular rectifier is the first step toward the fabrication of nanoscale unimolecular electronic circuit elements. For instance, a nanoscale current transistor will enable the future molecular computer to be much denser, smaller, and faster than present computers, provided that the size of each element (rectifier, resistor, transistor) is small (3-10 nm) and the speed of electron transfer through the element is fast (<1 ns). Macroscopic current-voltage measurements reveal asymmetries in the DC electrical conductivity, probably due to an intramolecular electron transfer, through Langmuir-Blodgett multilayers and even monolayers of ?-(n-hexadecyl)quinolinum tricyanoquinodimethanide, C16H33Q- 3CNQ (1). The data showing rectification in the expected direction and some rectification in the reverse direction are analyzed and discussed. Thu through-film electrical conductivity of Langmuir-Blodgett monolayer films of 1 was studied as a function of temperature. The current is usually smaller at low temperature, but rectification was observed between 370 K and 105 K, with a rectification ratio as large at 105 K as at room temperature. Unimolecular electrical rectification by monolayers of molecule 1 is unequivocally confirmed. The sandwich ``Al | LB monolayer of 1 | Al'' is the smallest rectifier in the world. The details of the fabrication of the sandwich, the instrumentation, as well as the electrical circuit are described. The core-level N1s XPS spectrum reveals the three expected N valence states. The valence-level XPS spectrum can be correlated with theory. Pressure/area isotherms, film transfer, and rectification of five analogs of the molecule were studied, but no rectification was observed on these systems. Pressure/area isotherms of four cholesterol derivatives and a fullerene derivative are reported. Preliminary work on a molecular transistor is also reported. Future work on low-temperature measurements with an improved sandwich structure, and on a molecular transistor is proposed.

Chen, Bo

62

Inward-Rectifying K+ Channels in Root Hairs of Wheat (A Mechanism for Aluminum-Sensitive Low-Affinity K+ Uptake and Membrane Potential Control).  

PubMed Central

K+ is the most abundant cation in cells of higher plants, and it plays vital roles in plant growth and development. Extensive studies on the kinetics of K+ uptake in roots have shown that K+ uptake is mediated by at least two transport mechanisms, one with a high and one with a low affinity for K+. However, the precise molecular mechanisms of K+ uptake from soils into root epidermal cells remain unknown. In the present study we have pursued the biophysical identification and characterization of mechanisms of K+ uptake into single root hairs of wheat (Triticum aestivum L.), since root hairs constitute an important site of nutrient uptake from the soil. These patch-clamp studies showed activation of a large inward current carried by K+ ions into root hairs at membrane potentials more negative than -75 mV. This K+ influx current was mediated by hyperpolarization-activated K+-selective ion channels, with a selectivity sequence for monovalent cations of K+ > Rb+ [almost equal to] NH4+ >> Na+ [almost equal to] Li+ > Cs+. Kinetic analysis of K+ channel currents yielded an apparent K+ equilibrium dissociation constant (Km) of [almost equal to]8.8 mM, which closely correlates to the major component of low-affinity K+ uptake. These channels did not inactivate during prolonged stimulation and would thus enable long-term K+ uptake driven by the plasma membrane proton-extruding pump. Aluminum, which is known to inhibit cation uptake at the root epidermis, blocked these inward-rectifying K+ channels with half-maximal current inhibition at [almost equal to]8 [mu]M free Al3+. Aluminum block of K+ channels at these Al3+ concentrations correlates closely to Al3+ phytotoxicity. It is concluded that inward-rectifying K+ channels in root hairs can function as both a physiologically important mechanism for low-affinity K+ uptake and as regulators of membrane potential. The identification of this mechanism is a major step toward a detailed molecular characterization of the multiple components involved in K+ uptake, transport, and membrane potential control in root epidermal cells. PMID:12232295

Gassmann, W.; Schroeder, J. I.

1994-01-01

63

Thin-film semiconductor rectifier has improved properties  

NASA Technical Reports Server (NTRS)

Cadmium selenide-zinc selenide film is used as a thin film semiconductor rectifier. The film is vapor-deposited in a controlled concentration gradient into a glass substrate to form the required junctions between vapor-deposited gold electrodes.

1966-01-01

64

Features of Controlled Laser Thermal Cleavage of Crystalline Silicon  

SciTech Connect

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.

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

2010-11-15

65

International Rectifier - Application Training Guide  

NSDL National Science Digital Library

This website is International Rectifier's directory page to an application training guide for topics such as Basic Circuit Theory, Basic Semiconductor Theory, Device Cross Section, Mounting Techniques, and Typical Applications. Includes a glossary of acronyms.

66

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

Microsoft Academic Search

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

Michael R. Blatt; Fiona Armstrong

1993-01-01

67

Modeling, control and implementation of the quasi-single stage three-phase zero-voltage zero-current switched buck rectifier  

Microsoft Academic Search

Large signal average model for the quasi-single stage three-phase zero-voltage zero-current switched (ZVZCS) buck rectifier operated with space vector modulation (SVM) is developed. The model reveals strong nonlinear relations between applied and effective duty-cycles, near the 60° electric sector boundaries, which lead to high input current distortion and output voltage ripple inadmissible in telecommunications applications. PLL and look-up table based

C. Cuadros; S. Chandrasekaran; K. Wang; D. Boroyevich; F. C. Lee

1999-01-01

68

Potential for improved silicon ribbon growth through thermal environment control  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

69

Treatment to Control Adhesion of Silicone-Based Elastomers  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

70

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

SciTech Connect

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

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

2014-03-10

71

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

PubMed

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

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

2014-07-01

72

Multigigahertz voltage-controlled oscillators in advanced silicon bipolar technology  

Microsoft Academic Search

Relaxation-type monolithic silicon bipolar voltage-controlled oscillators (VCOs) with center frequencies ranging from 1.5 to 5 GHz are described. The maximum oscillating frequency achieved is 7.4 GHz. The VCOs dissipate about 70 mW from a 3.6-V supply, including the output buffer and voltage-to-current converter stages. Two types of on-chip timing capacitor structure and various configurations used in achieving these results are

Mehmet Soyuer; James D. Warnock

1992-01-01

73

Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon  

SciTech Connect

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

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

2014-02-07

74

Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon  

NASA Astrophysics Data System (ADS)

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

Zheng, D. Q.; Su, W. A.; Ye, Q. H.; Shen, W. Z.

2014-02-01

75

Scofield, et. al., Review of Scientific Instruments 61, 1994-6 (July 1990) SIMPLE EVAPORATION CONTROLLER FOR THIN FILM DEPOSITION  

E-print Network

is not sufficient so that an electronic feedback control system is required. Such is the case, for instance controller" to perform the high-current switching. This unit, built around a silicon controlled rectifier CONTROLLER FOR THIN FILM DEPOSITION FROM A RESISTIVELY HEATED BOAT John H. Scofield, Lou Bajuk, and William

Scofield, John H.

76

Humidity sensing properties of morphology-controlled ordered silicon nanopillar  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

77

Crystallization of silicon nanoclusters with inert gas temperature control  

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

78

Nanostructured Silicon Membranes for Control of Molecular Transport  

SciTech Connect

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

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

2010-01-01

79

Experimental investigation of radiative thermal rectifier using vanadium dioxide  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

80

Physics of the frequency response of rectifying organic Schottky diodes  

NASA Astrophysics Data System (ADS)

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

Altazin, Stéphane; Clerc, Raphaël; Gwoziecki, Romain; Verilhac, Jean-Marie; Boudinet, Damien; Pananakakis, Georges; Ghibaudo, Gérard; Chartier, Isabelle; Coppard, Romain

2014-02-01

81

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

PubMed

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

Van Dyck, Colin; Ratner, Mark A

2015-03-11

82

Theoretical study of donor–spacer–acceptor structure molecule for use as stable molecular rectifier: geometric and electronic structures  

Microsoft Academic Search

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

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

2003-01-01

83

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2010-10-01

84

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2011-10-01

85

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Semiconductor rectifier systems. 120.360 Section...Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2010-10-01

86

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Semiconductor rectifier systems. 120.360 Section...Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2011-10-01

87

Practical application of MOSFET synchronous rectifiers  

Microsoft Academic Search

The application of MOSFET synchronous rectifiers (SRs) to a forward power converter with resonant reset is analyzed. Under the assumptions of ideal gate-drive waveforms, the theoretical minimum losses are determined. The analysis shows that the gate charge and on-resistance of the current generation of power MOSFETs are low enough to yield a significant increase in rectifier efficiency. Two simple gate

James Blanc

1991-01-01

88

Effects of Rectifiers on System Wave Shape  

Microsoft Academic Search

Operation of mercury arc rectifiers generally results in increased harmonic currents in the rectifier supply circuits and may result in increased harmonic voltages. While these harmonics usually are not serious From the standpoint of the power system, they may result in interference to communication circuits exposed to the power circuits. This paper presents a method of computing these harmonic voltages

P. W. Blye; H. E. Kent

1934-01-01

89

Properties of Welded Contact Germanium Rectifiers  

Microsoft Academic Search

In the contact rectifier described, the cat whisker has been solidly welded to a germanium surface. The welding process has brought about several extraordinary properties not found in the usual point rectifier: (1) Mechanical stability is achieved without the use of a compound to fill the cartridge. Protection against moisture is gained through the use of a glass-metal seal. (2)

H. Q. North

1946-01-01

90

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

DOEpatents

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

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

2009-10-13

91

Ordered silicon nanorod arrays with controllable geometry and robust hydrophobicity  

NASA Astrophysics Data System (ADS)

Highly ordered silicon nanorod (SiNR) arrays with controllable geometry are fabricated via nanosphere lithography and metal-assisted chemical etching. It is demonstrated that the key to achieving a high-quality metal mask is to construct a non-close-packed template that can be removed with negligible damage to the mask. Hydrophobicity of SiNR arrays of different geometries is also studied. It is shown that the nanorod structures are effectively quasi-hydrophobic with a contact angle as high as 142°, which would be useful in self-cleaning nanorod-based device applications. Project supported by the National Natural Science Foundation of China (Grant No. 51272246) and the Scientific and Technological Research Foundation of Anhui Province, China (Grant No. 12010202035).

Zi-Wen, Wang; Jia-Qi, Cai; Yi-Zhi, Wu; Hui-Jie, Wang; Xiao-Liang, Xu

2015-01-01

92

Very low forward drop JBS rectifiers fabricated using submicron technology  

Microsoft Academic Search

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

M. Mehrota; B. J. Baliga

1993-01-01

93

Approaching the downsizing limit of silicon for surface-controlled lithium storage.  

PubMed

Graphene-sheet-supported uniform ultrasmall (?3 nm) silicon quantum dots have been successfully synthesized by a simple and effective self-assembly strategy, exhibiting unprecedented fast, surface-controlled lithium-storage behavior and outstanding lithium-storage properties including extraordinary rate capability and remarkable cycling stability, attributable to the intrinsic role of approaching the downsizing limit of silicon. PMID:25581500

Wang, Bin; Li, Xianglong; Luo, Bin; Hao, Long; Zhou, Min; Zhang, Xinghao; Fan, Zhuangjun; Zhi, Linjie

2015-03-01

94

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

Microsoft Academic Search

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

Gi-Taek Kim; T.A. Lipo

1995-01-01

95

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

Microsoft Academic Search

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

Gi-Taek Kim; Thomas A. Lipo

1996-01-01

96

Control mechanisms for the oceanic distribution of silicon isotopes  

Microsoft Academic Search

Marine diatoms take up silicic acid for the buildup of their opaline shells and discriminate against the heavier silicon isotope. For the first time, the overall oceanic distribution of silicon isotopes has been estimated by integration of the Hamburg Model of the Ocean Carbon Cycle, version 4 (HAMOCC4). It is shown that the relationship between the silicic acid concentration and

André G. Wischmeyer; Christina L. De La Rocha; Ernst Maier-Reimer; Dieter A. Wolf-Gladrow

2003-01-01

97

A boron nitride nanotube peapod thermal rectifier  

NASA Astrophysics Data System (ADS)

The precise guidance of heat from one specific location to another is paramount in many industrial and commercial applications, including thermal management and thermoelectric generation. One of the cardinal requirements is a preferential conduction of thermal energy, also known as thermal rectification, in the materials. This study introduces a novel nanomaterial for rectifying 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.

Loh, G. C.; Baillargeat, D.

2014-06-01

98

Noise-compensating pulses for electrostatically controlled silicon spin qubits  

NASA Astrophysics Data System (ADS)

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, "?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%-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.

Wang, Xin; Calderon-Vargas, F. A.; Rana, Muhed S.; Kestner, J. P.; Barnes, Edwin; Das Sarma, S.

2014-10-01

99

Control of carbon balance in a silicon smelting furnace  

DOEpatents

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.

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

1992-12-29

100

Vacuum-stripped silicone binder for thermal-control paint  

NASA Technical Reports Server (NTRS)

Silicone elastomer is placed in evacuating system, heated to 160 C and held at this temperature for 24 hours. Elastomer is then cooled to room temperature in vacuum, producing upgraded, low outgassing polymer of increased molecular weight.

Gilligan, J. E.; Rogers, F. O.

1973-01-01

101

Geometry control of recrystallized silicon wafers for solar applications  

E-print Network

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

Ruggiero, Christopher W

2009-01-01

102

Simulation of fuel-cell stacks using a computer-controlled power rectifier with the purposes of actual high-power injection applications  

Microsoft Academic Search

This paper presents the guidelines for simulation of fuel-cell (FC) stacks by using a computer-controlled high-power converter, which drives actual electric loads, or injects power to the grid. The FC output static and dynamic characteristics are closely reproduced in such a way the actual loads are seamlessly driven as if they were supplied by the simulated FC. The simulator characteristics

Jeferson M. Corrêa; Felix A. Farret; Jonas R. Gomes; Marcelo Godoy Simões

2003-01-01

103

Electron beam quality control using an amorphous silicon EPID  

SciTech Connect

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.

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

104

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

Microsoft Academic Search

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

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

2003-01-01

105

PWM rectifier with low dc voltage ripple for magnet supply  

SciTech Connect

PWM bridge rectifiers with GTO switches are considered for application to particle accelerator magnet power supplies, where two-quadrant operation and extremely low dc current ripple are required. Different control strategies, with both preprogrammed and variable switching patterns, are examined and compared in view of optimization of the system performance. In particular, optimum digital PWM, multilevel delta modulation, and hybrid PWM/delta techniques are analyzed. In this paper the validity of the control methods is verified by simulation and experimental tests on a 60-kW prototype.

Ciscato, D. (Dept. of Electronics and Informatics, Univ. of Padova, Padova (Italy)); Malesani, L.; Rosetto, L.; Tenti, P. (Dept. of Electrical Engineering, Univ. of Padova, Padova (Italy)); Basile, G.L.; Pasti, M. (OCEM SpA, San Giorgio di Piano (Italy)); Voelker, F. (Proton Synchrotron Div., CERN, Geneva (Switzerland))

1992-04-01

106

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

Microsoft Academic Search

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

John C. Salmon

1995-01-01

107

The control of oscillation mode in silicon microbeams using silicon nitride anchor  

NASA Astrophysics Data System (ADS)

We designed and fabricated gravimetric sensors composed of silicon (Si) microbeams surrounded by silicon nitride (SiN) anchors. The oscillation properties of the fabricated devices show that a single oscillation mode originating from quasi-one-dimensional microbeams appears at an applied alternating electric field, which motion is well matched to the theoretical predictions and is much different from the dimensionally mixed oscillation modes in normal non-anchored devices. In addition, in order to elucidate the possibilities of the devices for mass sensing applications, we measured the frequency shift as a function of mass loading in a self-assembled monolayer of 3-aminopropyltrimethoxysilane and Au nanoparticles. The resulting limit of detection was 1.05 × 10-18 g/Hz, which is an extremely high value for micro electromechanical system gravimetric sensors relative to the normal ones.

Baek, In-Bok; Lee, Bong Kuk; Kim, Yarkyeon; Ahn, Chang-Geun; Kim, Young Jun; Yoon, Yong Sun; Jang, Won Ik; Kim, Hakseong; Lee, Sang Wook; Lee, Seongjae; Yu, Han Young

2014-09-01

108

Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor  

NASA Technical Reports Server (NTRS)

A process for producing polycrystalline silicon carbide includes heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

2000-01-01

109

Process to produce silicon carbide fibers using a controlled concentration of boron oxide vapor  

NASA Technical Reports Server (NTRS)

A process for producing polycrystalline silicon carbide by heating an amorphous ceramic fiber that contains silicon and carbon in an environment containing boron oxide vapor. The boron oxide vapor is produced in situ by the reaction of a boron containing material such as boron carbide and an oxidizing agent such as carbon dioxide, and the amount of boron oxide vapor can be controlled by varying the amount and rate of addition of the oxidizing agent.

Barnard, Thomas Duncan (Inventor); Lipowitz, Jonathan (Inventor); Nguyen, Kimmai Thi (Inventor)

2001-01-01

110

Controls on silicon cycling in Southeast Asian rice production systems  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

111

82559ER Fast Ethernet PCI Controller Networking Silicon  

E-print Network

-- Networking Silicon ii Datasheet Information in this document is provided in connection with Intel products by this document. Except as provided in Intel's Terms and Conditions of Sale for such products, Intel assumes of Intel products including liability or warranties relating to fitness for a particular purpose

Gummadi, Ramakrishna

112

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

DOEpatents

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

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

1980-08-26

113

Novel plasma control method in PECVD for preparing microcrystalline silicon  

SciTech Connect

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

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

1997-07-01

114

An automatic singing voice rectifier design  

Microsoft Academic Search

This paper proposes a new approach to automatic singing voice rectification. There are two components in the rectifier; one is the recognizer based on dynamic time warping and the other is the synthesizer based PSOLA (Pitch Synchronous Overlap and Add) for pitch shifting. The purpose of the recognizer is to identify the locations of off-key parts of the user's acoustic

Cheng-Yuan Lin; Jyh-Shing Roger Jang; Mao-Yuan Hsu

2003-01-01

115

The accuracy of rectifier-photoelectric cells  

Microsoft Academic Search

The effect of a resistance R in series with a rectifier-photoelectric cell on (a) the linearity of the response and (b) the temperature coefficient of the sensitivity has been investigated. In order that no restriction should be imposed on R by the effective sensitivity, the photoelectric current was measured by compensation. The light sources used in these experiments were tungsten

J R Atkinson; N R Campbell; E H Palmer; G T Winch

1938-01-01

116

Input Impedance Modeling of Multipulse Rectifiers by Harmonic Linearization  

Microsoft Academic Search

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

Jian Sun; Zhonghui Bing; Kamiar J. Karimi

2009-01-01

117

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

NASA Astrophysics Data System (ADS)

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

Wang, Chenlei

118

Research on Application of Novel Harmonic Suppression Rectifier Transformer and Its Filter System in the Electrolysis Rectifier System  

Microsoft Academic Search

A novel harmonic suppression rectifier transformer and its filter system based on transformer inductive filtering technology is proposed in this paper for the electrolytic rectifier system. The proposed rectifier transformer adopts three-winding structure, in which, the power winding at the primary side adopts star connection scheme, and both load and filter windings at the secondary side adopt delta connection scheme.

Jianying Li; Longfu Luo; Jiazhu Xu; Jinhui Zeng

2010-01-01

119

Controlling optical properties and surface morphology of dry etched porous silicon  

NASA Astrophysics Data System (ADS)

Porous silicon is a potentially useful substrate for fluorescence and scattering enhancement, with a large surface to volume ratio and thermal stability providing a potentially regenerable host matrix for sensor development. A simple process using XeF2 gas phase etching for creating porous silicon is explained. Moreover, how pores diameter can be controlled reproducibly with commensurate effects upon the silicon reflection and pore distribution is discussed. In previous work with this new system, it was clear that control on pore size and morphology was required and a systematic optimization of process conditions was performed to produce greater consistency of the result. The influence of the duration of the pre-etching processing in HF, concentration of the HF in the pre-etching process, and the XeF2 exposure time during the dry etching on surface morphology, pore size, and optical reflectance is explored.

Cheung, Maurice C.-K.; Roche, Philip J. R.; Hajj-Hassan, Mohamad; Kirk, Andrew G.; Mi, Zetian; Chodavarapu, Vamsy P.

2011-01-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

121

D0 Silicon Upgrade: Control Dewar Valve Calculations  

SciTech Connect

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.

Rucinski, Russ; /Fermilab

1995-10-20

122

A comparative study of high voltage (4 kV) power rectifiers PiN\\/MPS\\/SSD\\/SPEED  

Microsoft Academic Search

This paper provides for the first time a comparative experimental study of different high voltage power rectifier structures designed based on the anode injection efficiency control concept. Trade-off curves of peak reverse current density, reverse recovery charge extracted and reverse dJ\\/dt versus forward voltage drop showed the merged PiN-Schottky (MPS), self-adapting P-emitter diode (SPEED), and static shielding diode (SSD) rectifiers

S. Sawant; B. J. Baliga

1999-01-01

123

An optical leaky wave antenna with silicon perturbations for electronic control  

NASA Astrophysics Data System (ADS)

An optical leaky wave antenna (OLWA) is a device that radiates a light wave into the surrounding space from a leaky wave (LW) guided mode or receives optical power from the surrounding space into a guided optical mode. In this work, we propose and provide a 3D analysis of a novel CMOS compatible OLWA made of a silicon nitride (Si3N4) waveguide comprising periodic silicon perturbations which allow electronic tuning capability. The analysis presented here includes the effect of the number of semiconductor perturbations, the antenna radiation pattern and directivity. We show that the number of the silicon perturbations has to be large to provide a long radiating section required to achieve radiation with high directivity. In other words, the proposed structure allows for a very narrow-beam radiation. Preliminary results are confirmed by exploiting leaky wave and antenna array factor theory, as well as verified by means of two full-wave simulators (HFSS and COMSOL). Our purpose is to ultimately use PIN junctions as building blocks for each silicon implantation for the electronic control of the radiation. In particular, the electronic tunability of the optical parameters of silicon (such as refractive index and absorption coefficient) via current injection renders itself the ideal platform for optical antennas that can facilitate electronic beam control, and boost the efficiency of optoelectronic devices such as light-emitting diodes, lasers and solar cells, and bio-chemical sensors.

Campione, Salvatore; Song, Qi; Boyraz, Ozdal; Capolino, Filippo

2011-10-01

124

Silicon-pyrene/perylene hybrids as molecular rectifiers.  

PubMed

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

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

2015-01-21

125

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

E-print Network

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

Paris-Sud XI, Université de

126

Input Vector Control for Post-Silicon Leakage Current Minimization in the Presence of Manufacturing Variability  

E-print Network

Input Vector Control for Post-Silicon Leakage Current Minimization in the Presence of Manufacturing for an inverter of nominal size in 0.18um model from MOSIS that is simulated using the leakage current in CadenceA10x leakage 1Input Figure 1: Series inverters and their leakage currents. If A has the nominal

Potkonjak, Miodrag

127

A Bayesian Approach to Diameter Estimation in the Diameter Control System of Silicon Single Crystal Growth  

Microsoft Academic Search

In the diameter control system of silicon single crystal growth, the variation of the diameter of the aperture (i.e., a halo with high brightness, which appears at the junction of a solid crystal and a liquid solution) is consistent with the change in the diameter of the growing crystal. Therefore, the diameter of the aperture can be used as a

Ding Liu; Junli Liang

2011-01-01

128

Controlled modification of erbium lifetime in silicon dioxide with metallic Jiming Bao,a  

E-print Network

Controlled modification of erbium lifetime in silicon dioxide with metallic overlayers Jiming Bao the radiative properties of erbium can be achieved in erbium-implanted materials in a wide range of implantation radiative lifetime, due to spontaneous emission, as well as by its nonradiative interactions

Bao, Jiming

129

Six Unimolecular Rectifiers and What Lies Ahead  

NASA Astrophysics Data System (ADS)

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 towards one-molecule electronic devices, useful for the ultimate reduction in circuit sizes.

Metzger, Robert M.

130

pH-controlled silicon nanowires fluorescence switch  

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

131

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.

132

EFFECT OF CAST RECTIFIERS ON THE MARGINAL FIT OF UCLA ABUTMENTS  

PubMed Central

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

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

2007-01-01

133

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

SciTech Connect

The surface photovoltage method is used to study “silicon-on-sapphire” epitaxial layers with a thickness of 0.3–0.6 ?m, which are used to fabricate p-channel MOS (metal—oxide-semiconductor) transistors with improved radiation hardness. It is shown that the manner in which the photoconductivity of the epitaxial layer decays after the end of a light pulse generated by a light-emitting diode (wavelength ?400 nm) strongly depends on the density of structural defects in the bulk of the structure. This enables control over how a “silicon-on-sapphire” structure is formed to provide the manufacturing of MOS structures with optimal operating characteristics.

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

2014-12-15

134

Over-Modulation Technique of Three-Phase Current Source Rectifier Based on FPGA  

Microsoft Academic Search

This paper introduces an over-modulation technique, a continuous extension of space vector PWM (SVPWM) linear control scheme for the three-phase current source rectifier (CSR). By judging the magnitude of active current vectors durations, this technique can select the current vectors in sectors and modify their active durations. It is neither necessary to store a lot of data in advance nor

Y. Li; Yonglong Peng; Heming Li

2007-01-01

135

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

PubMed

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

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

2015-02-01

136

Coherent control of single spins in silicon carbide at room temperature  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

137

Energy-harvesting shock absorber with a mechanical motion rectifier  

NASA Astrophysics Data System (ADS)

Energy-harvesting shock absorbers are able to recover the energy otherwise dissipated in the suspension vibration while simultaneously suppressing the vibration induced by road roughness. They can work as a controllable damper as well as an energy generator. An innovative design of regenerative shock absorbers is proposed in this paper, with the advantage of significantly improving the energy harvesting efficiency and reducing the impact forces caused by oscillation. The key component is a unique motion mechanism, which we called ‘mechanical motion rectifier (MMR)’, to convert the oscillatory vibration into unidirectional rotation of the generator. An implementation of a MMR-based harvester with high compactness is introduced and prototyped. A dynamic model is created to analyze the general properties of the motion rectifier by making an analogy between mechanical systems and electrical circuits. The model is capable of analyzing electrical and mechanical components at the same time. Both simulation and experiments are carried out to verify the modeling and the advantages. The prototype achieved over 60% efficiency at high frequency, much better than conventional regenerative shock absorbers in oscillatory motion. Furthermore, road tests are done to demonstrate the feasibility of the MMR shock absorber, in which more than 15 Watts of electricity is harvested while driving at 15 mph on a smooth paved road. The MMR-based design can also be used for other applications of vibration energy harvesting, such as from tall buildings or long bridges.

Li, Zhongjie; Zuo, Lei; Kuang, Jian; Luhrs, George

2013-02-01

138

Controlling the spectrum of photons generated on a silicon nanophotonic chip  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

139

Development of fluorocarbon evaporative cooling recirculators and controls for the ATLAS inner silicon tracker  

E-print Network

We report on the development of evaporative fluorocarbon cooling recirculators and their control systems for the ATLAS inner silicon tracker. We have developed a prototype circulator using a dry, hermetic compressor with C/sub 3/F/sup 8/ refrigerant, and have prototyped the remote-control analog pneumatic links for the regulation of coolant mass flows and operating temperatures that will be necessary in the magnetic field and radiation environment around ATLAS. pressure and flow measurement and control use 150+ channels of standard ATLAS LMB ("Local Monitor Board") DAQ and DACs on a multi-drop CAN network administered through a BridgeVIEW user interface. A hardwired thermal interlock system has been developed to cut power to individual silicon modules should their temperatures exceed safe values. Highly satisfactory performance of the circulator under steady state, partial-load and transient conditions was seen, with proportional fluid flow tuned to varying circuit power. Future developments, including a 6 kW...

Bayer, C; Bonneau, P; Bosteels, Michel; Burckhart, H J; Cragg, D; English, R; Hallewell, G D; Hallgren, Björn I; Ilie, S; Kersten, S; Kind, P; Langedrag, K; Lindsay, S; Merkel, M; Stapnes, Steinar; Thadome, J; Vacek, V

2000-01-01

140

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

NASA Technical Reports Server (NTRS)

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

1972-01-01

141

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

SciTech Connect

The Continuous Casting Method (CCM) has been designed to obtain low cost silicon wafers. This method has the objective of wafer cost reduction by mass production effect through the installation of a mold pre-heating zone and a crystal growth and cooling zone separately on both sides of a silicon melting and injecting zone. The authors have developed the Drip-Controlled Method (DCM) as a casting method for CCM. In DCM, the injection of molten silicon and the crystal growth are carried out simultaneously and the heat of molten silicon is utilized actively as a heat source to control the crystal growth. DCM is the most effective casting method for continuous casting. Batch-type ingots with a size of 320 mm square, height 260--300 mm, were produced by DCM. An oxygen content of 5--15 ppma and a carbon content of less than 5 ppma were obtained throughout the ingots. The cell efficiency yield of more than 13.5% was 80% against the growth direction, with a wafer size of 100 mm x 100 mm using the standard cell process. A maximum value was found of 14.3% measured in JQA. The solar cell efficiency, the carrier lifetime and the diffusion length measured in this study showed DCM had an advantage for obtaining one-directional growth and columnar structure.

Goda, Shinji; Moritani, Toshiaki; Hatanaka, Yuji; Shimizu; Hiroaki; Hide, Ichiro [Daido Hoxan Inc., Chitose, Hokkaido (Japan). Chitose Lab.

1994-12-31

142

Single-shot readout and microwave control of an electron spin in silicon  

NASA Astrophysics Data System (ADS)

The electron spin of a donor in silicon is an excellent candidate for a solid-state qubit. It is known to have very long coherence and relaxation times in bulk [1], and several architectures have been proposed to integrate donor spin qubits with classical silicon microelectronics [2]. Here we show the first experimental proof of single-shot readout of an electron spin in silicon. The device consists of implanted phosphorus donors, tunnel-coupled to a silicon Single-Electron Transistor (SET), where the SET island is used as a reservoir for spin-to-charge conversion [3]. The large charge transfer signals allow readout fidelity >90% with 3 ?s response time. By measuring the occurrence of excited spin states as a function of wait time, we find spin lifetimes (T1) up to ˜ 6 s at B = 1.5 T, and a magnetic-field dependence T1-1 B^5 consistent with that of phosphorus donors in silicon [4]. In a subsequent experiment we have integrated the single-shot spin readout device with an on-chip microwave transmission line for coherent control of the electron spin. We have detected the spin resonance of a single electron, and observed two hyperfine-split resonance lines, consistent with Stark-shifted coupling to the ^31P nuclear spin. Further experiments are underway to demonstrate coherent spin control and observe Rabi oscillations. This demonstrates the microwave control of a single spin, combined -- for the first time in the same experiment -- with electrically detected single-shot spin readout. [1] A. M. Tyryshkin et al., Phys. Rev. B 68, 193207 (2003). [2] L. C. L. Hollenberg et al., Phys. Rev. B. 74, 045311 (2006). [3] A. Morello et al., Phys. Rev. B 80, 081307(R) (2009). [4] A. Morello et al., Nature 467, 687 (2010).

Morello, Andrea

2011-03-01

143

Interface charge control of directly bonded silicon structures  

NASA Astrophysics Data System (ADS)

The influence of interface states and charges on the properties of Si/Si and Si/SiO2 interfaces prepared by wafer bonding, using the direct bonding technique, has been investigated. Surface potentials of Si/Si interfaces with all combinations of doping type (n-n,p-p,p-n) are dependent on surface and heat treatments in the bonding procedure and on wafer dopant concentration. In earlier reported works, hydrophilic wafer surface properties have been reported as necessary for a good mechanical bonding. We find that wafer treatment in HF giving hydrophobic surfaces not only gives good mechanical properties, but also better electronic properties as well. For all combinations of doping type, lower magnitudes in surface potential were measured in samples prepared from wafers pretreated in HF in order to etch off the native oxide layer, normally present on silicon surfaces. If a native oxide is present when the bonded interface is prepared, the current through the interface will be influenced by an energy barrier due to the presence of charged interface states. The amount of charge trapped at the interface has been found to be dependent on the applied bias. A theoretical description is made for the Si/Si interfaces, and predictions are compared to results obtained from electrical measurements. Based on this theory, using data from the current-voltage characteristic, an interface state density in the region 5×1010-1012 cm-2 eV-1 at the bonded interface has been deduced for different samples. Bonded Si/SiO2 interfaces with interface state densities of about 1011 cm-2 eV-1 and low flat-band voltages have been achieved. No influence of different chemical pretreatments, used in this paper, on properties of bonded Si/SiO2 interfaces, as seen in flat-band voltage and interface state density, was found, although the bonding process is critical in the preparation of the Si/SiO2 interfaces.

Bengtsson, Stefan; Engström, Olof

1989-08-01

144

Silicon-Germanium Voltage-Controlled Oscillator at 105 GHz  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

145

Controlled oxidation, biofunctionalization, and patterning of alkyl monolayers on silicon and silicon nitride surfaces using plasma treatment.  

PubMed

A new method is presented for the fast and reproducible functionalization of silicon and silicon nitride surfaces coated with covalently attached alkyl monolayers. After formation of a methyl-terminated 1-hexadecyl monolayer on H-terminated Si(100) and Si(111) surfaces, short plasma treatments (1-3 s) are sufficient to create oxidized functionalities without damaging the underlying oxide-free silicon. The new functional groups can, e.g., be derivatized using the reaction of surface aldehyde groups with primary amines to form imine bonds. In this way, plasma-treated monolayers on silicon or silicon nitride surfaces were successfully coated with nanoparticles, or proteins such as avidin. In addition, we demonstrate the possibility of micropatterning, using a soft contact mask during the plasma treatment. Using water contact angle measurements, ellipsometry, XPS, IRRAS, AFM, and reflectometry, proof of principle is demonstrated of a yet unexplored way to form patterned alkyl monolayers on oxide-free silicon surfaces. PMID:19728734

Rosso, Michel; Giesbers, Marcel; Schroën, Karin; Zuilhof, Han

2010-01-19

146

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

NASA Astrophysics Data System (ADS)

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

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

2003-03-01

147

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.

148

Development of high temperature gallium phosphide rectifiers  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

149

``Rectifying'' reflection from a magnetic photonic crystal  

NASA Astrophysics Data System (ADS)

When an oscillating line source is placed in front of a special mirror consisting of an array of flat uniformly spaced ferrite rods, half of the image disappeared at some frequency. We believe that this comes from the coupling to photonic states of the magnetic surface plasmon band. These states exhibit giant circulations that only go in one direction due to time reversal symmetry breaking. Possible applications of this ``rectifying'' reflection include a robust one-way waveguide, a 90^o beam bender and a beam splitter, which are shown to work even in the deep subwavelength scale.

Liu, Shiyang; Lu, Wanli; Lin, Zhifang; Chui, S. T.

2010-03-01

150

Block of cardiac delayed-rectifier and inward-rectifier K+ currents by nisoldipine  

PubMed Central

The objective of this study was to determine the concentration-dependent effects of nisoldipine, a dihydropyridine Ca2+ channel blocker, on K+ currents in guinea-pig ventricular myocytes. Myocytes in the conventional whole-cell configuration were bathed in normal Tyrode's solution or K+-free Tyrode's solution for the measurement of the effects of 0.01–100 ?M nisoldipine on rapidly activating delayed-rectifier K+ current (IKr), slowly activating delayed-rectifier K+ current (IKs), inwardly rectifying K+ current (IK1), and reference L-type Ca2+ current (ICa,L). Nisoldipine inhibited IKr with an IC50 of 23 ?M, and IKs with an IC50 of 40 ?M. The drug also had weak inhibitory effects on inward- and outward-directed IK1; the IC50 determined for outward-directed current was 80 ?M. Investigation of nisoldipine action on IKs showed that inhibition occurred in the absence of previous pulsing, and with little change in the time courses of activation and deactivation. However, the drug-induced inhibition was significantly weaker at ?+30 mV than at +10 mV. We estimate that nisoldipine is about 30 times less selective for delayed-rectifier K+ channels than for L-type Ca2+ channels in fully polarised guinea-pig ventricular myocytes, and several orders less selective in partially depolarised myocytes. PMID:14530219

Missan, Sergey; Zhabyeyev, Pavel; Dyachok, Oksana; Jones, Stephen E; McDonald, Terence F

2003-01-01

151

Light controlled oscillators; pixel architecture for large area linear digital imaging using amorphous silicon  

Microsoft Academic Search

The theory of operation and experimental results of a light controlled thin film transistor (TFT) oscillator circuits in amorphous silicon (a-Si) technology are presented. The circuit consists of a three-stage ring oscillator made of a top-gate TFT as driver and a photoconductor detector as the load for each stage, all fabricated in-house using a four mask top-gate process. Measurements indicate

Farhad Taghibakhsh; Karim S. Karim

2008-01-01

152

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds  

Microsoft Academic Search

Formation conditions of two types of sodium containing silicon clathrate compounds were determined by the controlled thermal decomposition of sodium monosilicide NaSi under vacuum. The decomposition began at 360°C. Much higher decomposition temperatures and the presence of sodium metal vapor were favorable for the formation of type I clathrate compound Na8Si46. Type II clathrate compound NaxSi136 was obtained as a

Hiro-Omi Horie; Takashi Kikudome; Kyosuke Teramura; Shoji Yamanaka

2009-01-01

153

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

Microsoft Academic Search

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

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

2000-01-01

154

High precision quantum control of single donor spins in silicon  

E-print Network

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

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

2007-05-15

155

Quantum Entanglement and Spin Control in Silicon Nanocrystal  

PubMed Central

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

Berec, Vesna

2012-01-01

156

Inward rectifier current noise in frog skeletal muscle.  

PubMed Central

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

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

1984-01-01

157

Physics of the Frequency Response of Rectifying Organic Schottky Diodes  

E-print Network

frequency identification (RFID) tags on flexible substrates [1 - 3]. Several research groups have already.clerc@institutoptique.fr) Keywords: Organic Schottky diode, RFID Tag, rectifying circuit, Frequency, time dependent response circuit, such as an RFID tag, has been investigated in detail. The time dependent response of rectifying

Paris-Sud XI, Université de

158

Sensorless Operation of a PWM Rectifier for a Distributed Generation  

Microsoft Academic Search

This paper presents a power converter configuration interfaced with the distributed ac power generation system to regulate the dc bus voltage. It is composed of a pulsewidth modulation (PWM) rectifier directly tied to the generator's terminals without ac reactors. Hence terminal voltages are not useful due to the switched pulse of the PWM rectifier and also it is not the

Hyunjae Yoo; Jang-Hwan Kim; Seung-Ki Sul

2007-01-01

159

Variants of rectifiers with near sinusoidal input currents  

Microsoft Academic Search

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

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

2011-01-01

160

Conditional control of donor nuclear spins in silicon using Stark shifts  

E-print Network

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.

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

2014-05-28

161

Controlled line shaped electron beam for silicon zone melting recrystallization on float glass substrates  

SciTech Connect

A line shaped electron beam system for the zone melting recrystallization (ZMR) of thick silicon films on float glass substrates is described. The low thermal stability of the glass requires a rapid regulated zone heating. The electron beam system allows the ZMR in a continuous scan without pulsing. The setup consists of the tungsten wire with a Pierce reflector as line cathode and the moving substrate as anode. A negative voltage applied on the reflectors limits the electron emission and provides the necessary control. The melt energy for optimized processing decreases with an increase of the velocity. The beam profiles and penetration depth of the electrons is discussed. Homogenous polycrystalline silicon areas of several 10 cm{sup 2} are achieved on a tungsten coated borosilicate float glass for the intended use as solar cell absorber.

Gromball, F.; Groth, C.; Mueller, J. [Department of Micro Systems Technology, Technical University Hamburg-Harburg, Eissendorfer Strasse 42, 21073 Hamburg (Germany)

2005-06-15

162

Improvement of thickness uniformity of bulk silicon wafer by numerically controlled local wet etching  

NASA Astrophysics Data System (ADS)

We have developed numerically controlled local wet etching (NC-LWE) as a novel deterministic subaperture figuring and finishing method, which is suitable for fabricating various optical components and for finishing functional materials. In this method, a chemical reaction between the etchant and the surface of the workpiece removes the surface without degrading the physical properties of the workpiece material. Furthermore, the processing properties of NC-LWE are insensitive to external disturbances, such as the vibration or thermal deformation of the machine or the workpiece, because of its noncontact removal mechanism. By applying the NC-LWE process using a HF/HNO 3 mixture to etch silicon, we corrected the thickness distribution of a bulk silicon wafer with a diameter of 200 mm and achieved a total thickness variation of less than 0.23 ?m within a diameter of 190 mm.

Nagano, Mikinori; Mitani, Takuro; Ueda, Kazuaki; Zettsu, Nobuyuki; Yamamura, Kazuya

2009-04-01

163

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

PubMed Central

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

2014-01-01

164

Insertion of intelligent hydrogel into silicone resin for thermal control applications  

NASA Astrophysics Data System (ADS)

As a kind of intelligent temperature-sensitive polymer, the poly (N-isopropylacrylamide) (PNIPA) hydrogel has lower critical solution temperature (LCST) of 33°C. PNIPA could change from transparency to opacification due to its phase separation. In this work, silicone coatings were doped with PNIPA particles, which were obtained by rotary cutting after N-isopropylacrylamide cross link reaction between N-isopropylacrylamide and N, N-methylenebisacrylamide in the aqueous solution below 20°C. The morphology and optical properties were characterized by SEM, FTIR and UV-Vis-NIR, respectively. The results show that combination of silicone resin and PNIPA particles enhances the diffuse reflection and operability in applications. It proves that the reversible thermal chronic property of PNIPA is useful for intelligent thermal control application.

Wei, Hua; Ge, Dengteng; Fan, Zeng; Liu, Chang; He, Xiaodong; Li, Yao

2009-07-01

165

Photoluminescent logic gate controlled by the optical Kerr effect exhibited by porous silicon  

NASA Astrophysics Data System (ADS)

The magnitude of the third order optical susceptibility exhibited by porous silicon monolayers was measured by a non-degenerated vectorial two-wave interaction. Optical irradiations at 488 nm and 532 nm wavelengths were employed to carry out the nonlinear optical experiments. Compared to bulk silicon material, a noticeable enhancement in the third order nonlinear optical response was identified. Photoluminescence and photoconductive properties were evaluated for the two studied wavelengths. The photoluminescent logic gate function AND was experimentally demonstrated using as a control a reflective optical Kerr gate configuration. A perceptible contribution for the third order optical nonlinearities seems to be related to the optical Kerr effect originated by excited states population. A two-level model was considered in order to describe the observed optical behavior.

de la Mora, M. B.; Torres-Torres, C.; Nava, R.; Trejo-Valdez, M.; Reyes-Esqueda, J. A.

2014-07-01

166

Candidate locations for SPS rectifying antennas  

NASA Technical Reports Server (NTRS)

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.

Eberhardt, A. W.

1977-01-01

167

Control of impurities transport in an industrial directional solidification furnace for silicon ingots basing on computer modeling  

NASA Astrophysics Data System (ADS)

Two kinds of local designs in an industrial directional solidification (DS) furnace were proposed to reduce oxygen (O) and carbon (C) concentrations in multi-crystalline silicon (mc-Si) ingots. Global simulations including coupled oxygen and carbon transport in the furnace were carried out. It was found that the proposed designs have little effect on the oxygen concentration in the silicon melt, while they could significantly influence the CO gas transport in the furnace and the C concentration in the silicon melt. The investigation provides a method to control the carbon impurity in an industrial DS furnace for mc-Si ingots.

Yu, Qinghua; Liu, Lijun; Zhong, Genxiang; Huang, Xinming

2013-07-01

168

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

NASA Astrophysics Data System (ADS)

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

Bui, Thanh Tung; Chien Dang, Mau

2014-11-01

169

A CMOS microdisplay with integrated controller utilizing improved silicon hot carrier luminescent light sources  

NASA Astrophysics Data System (ADS)

Microdisplay technology, the miniaturization and integration of small displays for various applications, is predominantly based on OLED and LCoS technologies. Silicon light emission from hot carrier electroluminescence has been shown to emit light visibly perceptible without the aid of any additional intensification, although the electrical to optical conversion efficiency is not as high as the technologies mentioned above. For some applications, this drawback may be traded off against the major cost advantage and superior integration opportunities offered by CMOS microdisplays using integrated silicon light sources. This work introduces an improved version of our previously published microdisplay by making use of new efficiency enhanced CMOS light emitting structures and an increased display resolution. Silicon hot carrier luminescence is often created when reverse biased pn-junctions enter the breakdown regime where impact ionization results in carrier transport across the junction. Avalanche breakdown is typically unwanted in modern CMOS processes. Design rules and process design are generally tailored to prevent breakdown, while the voltages associated with breakdown are too high to directly interact with the rest of the CMOS standard library. This work shows that it is possible to lower the operating voltage of CMOS light sources without compromising the optical output power. This results in more efficient light sources with improved interaction with other standard library components. This work proves that it is possible to create a reasonably high resolution microdisplay while integrating the active matrix controller and drivers on the same integrated circuit die without additional modifications, in a standard CMOS process.

Venter, Petrus J.; Alberts, Antonie C.; du Plessis, Monuko; Joubert, Trudi-Heleen; Goosen, Marius E.; Janse van Rensburg, Christo; Rademeyer, Pieter; Fauré, Nicolaas M.

2013-03-01

170

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

SciTech Connect

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

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

2002-04-01

171

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

PubMed Central

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

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

2011-01-01

172

Emerging roles for G protein-gated inwardly rectifying potassium (GIRK) channels in health and disease  

Microsoft Academic Search

G protein-gated inwardly rectifying potassium (GIRK) channels hyperpolarize neurons in response to activation of many different G protein-coupled receptors and thus control the excitability of neurons through GIRK-mediated self-inhibition, slow synaptic potentials and volume transmission. GIRK channel function and trafficking are highly dependent on the channel subunit composition. Pharmacological investigations of GIRK channels and studies in animal models suggest that

Christian Lüscher; Paul A. Slesinger

2010-01-01

173

Proposal of a Soft-Switching Single-Phase Three-Level Rectifier  

Microsoft Academic Search

This paper is concerned with the study of a single-phase boost-type three-level rectifier. The converter is supposed to present high input power factor, low current harmonics, low total harmonic distortion, and simple control scheme. In order to minimize switching losses, a passive nondissipative snubber is associated with the aforementioned converter. The theoretical analysis, design procedure, and analytical results regarding a

Fernando Lessa Tofoli; Ernane AntÔnio Alves Coelho; Luiz Carlos de Freitas; Valdeir JosÉ Farias; J. B. Vieira

2008-01-01

174

Rectifier characteristics based on bipolar-mode SIT operation  

SciTech Connect

A novel rectifier concept based on bipolar-mode static induction transistor (BSIT) operation is proposed. A numerical simulation has revealed that the turn-on mechanism of this rectifier, owing to a combination of static induction effects and minority carrier injection, can make its forward-voltage drop and reverse recovery time smaller than those of the conventional p-i-n rectifier. As an example of the design methods, the simulation has clarified the effects of decreasing the doping concentration in the chemical between p[sup +] regions on improvement in the tradeoff between a forward voltage drop and leakage current.

Yano, Koji; Kasuga, Masanobu; Shimizu, Azuma (Yamanashi Univ., Kofu (Japan). Dept. of Electrical Engineering and Computer Science); Mitsui, Masahito; Moroshima, Heiji; Morita, Junichi (Hitachi Ltd., Yamanashi (Japan). Semiconductor and Integrated Circuits Division)

1994-09-01

175

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

NASA Astrophysics Data System (ADS)

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

Valley, John F.; Sanna, M. Cristina

2014-08-01

176

Pore Size Control of Ultra-thin Silicon Membranes by Rapid Thermal Carbonization  

PubMed Central

Rapid thermal carbonization in a dilute acetylene (C2H2) atmosphere has been used to chemically modify and precisely tune the pore size of ultrathin porous nanocrystalline silicon (pnc-Si). The magnitude of size reduction was controlled by varying the process temperature and time. Under certain conditions, the carbon coating displayed atomic ordering indicative of graphene layer formation conformal to the pore walls. Initial experiments show that carbonized membranes follow theoretical predictions for hydraulic permeability and retain the precise separation capabilities of untreated membranes. PMID:20839831

Fang, David Z.; Striemer, Christopher C.; Gaborski, Thomas R.; McGrath, James L.; Fauchet, Philippe M.

2010-01-01

177

A feedback silicon-on-insulator steep switching device with gate-controlled carrier injection  

NASA Astrophysics Data System (ADS)

We experimentally demonstrate a field-effect transistor with a single front gate built on fully-depleted silicon-on-insulator substrate that possesses extremely steep switching slope (?1 mV/decade) and gate-controllable hysteresis. The mechanism for the sharp switching, confirmed by simulations, involves the positive feedback between the gate-modulated charge injection barriers and the electron and hole components of the source-drain current. The transistor is named Z2-FET as it features zero impact ionization (unlike thyristors) and zero subthreshold swing.

Wan, J.; Cristoloveanu, S.; Le Royer, C.; Zaslavsky, A.

2012-10-01

178

Control of Optical Performance in Infrared Region for Vanadium Dioxide Films Layered by Amorphous Silicon  

NASA Astrophysics Data System (ADS)

The multilayer structure of amorphous silicon ( a-Si) with vanadium dioxide (VO2) that possesses excellent thermochromism in the infrared range was formed by reactive magnetron sputtering. Then, the physical properties such as thermochromic performance, crystalline structure, and film morphology were investigated. As a result, the a-Si layer was found to flexibly control the optical-spectral variation due to thermochromism produced in the VO2 layer over a wide infrared range. The multilayer structure of VO2 between a-Si layers is an effective way to design various infrared thermochromic devices, since the refractive index of a-Si can be widely varied by oxidation.

Kakiuchida, H.; Jin, P.; Tazawa, M.

2010-10-01

179

Controlling the electronic band structures in hydrogenated silicon nanocrystals by shallow impurity doping  

NASA Astrophysics Data System (ADS)

By the aid of magnetic-field-dependent Hall effect measurements, we have extracted the electron mobility and concentration in hydrogenated Si nanocrystals grown on crystalline silicon substrates within the framework of mobility spectrum analysis. A unified model based on diffusive and ballistic transport mechanisms has been employed to explain the observed electron mobility in Si nanocrystals with different doping levels, as well as the mobility edge in low-doping Si nanocrystals. Both the theoretical and experimental results clearly demonstrate the control of the electronic band structures by shallow impurity phosphorus doping in Si nanocrystals, which provide an experimental basis for further nanoelectronic device design using Si nanocrystals.

Chen, X. Y.; Shen, W. Z.

2005-07-01

180

Controlling the spectrum of photons generated on a silicon nanophotonic chip  

PubMed Central

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

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

2014-01-01

181

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

SciTech Connect

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 multifunction 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.

Mrig, L.; Burdick, J.; Luft, W.; Kroposki, B.

1995-10-01

182

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

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

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

1995-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

184

Fault analysis of uncontrolled rectifier HVDC links for the connection of off-shore wind farms  

Microsoft Academic Search

The present paper introduces the use of an uncontrolled rectifier HVDC link for the connection of off-shore wind farms. The use of an uncontrolled rectifier instead of a line commutated thyristor (LCT) rectifier represents clear advantages in terms of installation cost and operation reliability. However, the rectifier can no longer be used to limit the HVDC link current during on-shore

R. Blasco-Gimenez; S. Ano-Villalba; J. Rodriguez; R. Pena; R. Cardenas; S. Bernal; F. Morant

2009-01-01

185

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

186

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

NASA Astrophysics Data System (ADS)

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, 5-10 nm rms, and the peak thermal wavelength is 0.6 ?m. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30 nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ?, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of ±8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

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

2014-03-01

187

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

SciTech Connect

We report on the diffusive-ballistic thermal conductance of multi-moded single-crystal silicon beams measured below 1?K. It is shown that the phonon mean-free-path ? is a strong function of the surface roughness characteristics of the beams. This effect is enhanced in diffuse beams with lengths much larger than ?, even when the surface is fairly smooth, 5–10?nm rms, and the peak thermal wavelength is 0.6??m. Resonant phonon scattering has been observed in beams with a pitted surface morphology and characteristic pit depth of 30?nm. Hence, if the surface roughness is not adequately controlled, the thermal conductance can vary significantly for diffuse beams fabricated across a wafer. In contrast, when the beam length is of order ?, the conductance is dominated by ballistic transport and is effectively set by the beam cross-sectional area. We have demonstrated a uniformity of ±8% in fractional deviation for ballistic beams, and this deviation is largely set by the thermal conductance of diffuse beams that support the micro-electro-mechanical device and electrical leads. In addition, we have found no evidence for excess specific heat in single-crystal silicon membranes. This allows for the precise control of the device heat capacity with normal metal films. We discuss the results in the context of the design and fabrication of large-format arrays of far-infrared and millimeter wavelength cryogenic detectors.

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

2014-03-28

188

Precision envelope detector and linear rectifier circuitry  

DOEpatents

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

Davis, Thomas J. (Richland, WA)

1980-01-01

189

Phosphoinositide regulation of inward rectifier potassium (Kir) channels  

PubMed Central

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

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

2014-01-01

190

The Implementation and Analysis of Over-modulation Technique of Three-phase Current Source Rectifier Based on FPGA  

Microsoft Academic Search

This paper introduces an over-modulation technique, a continuous extension of space vector PWM (SVPWM) linear control scheme for the three-phase current source rectifier (CSR). By judging the magnitude of active current vectors durations, this technique can select the current vectors in sectors and modify their active durations. It is neither necessary to store a lot of data in advance nor

Zhang Chunyu; Li Yabin; Wang Qi; Li Chengrong

2008-01-01

191

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

E-print Network

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, ...

Held, David (David A.)

2005-01-01

192

Novel micropatterns mechanically control fibrotic reactions at the surface of silicone implants.  

PubMed

Over the past decade, various implantable devices have been developed to treat diseases that were previously difficult to manage such diabetes, chronic pain, and neurodegenerative disorders. However, translation of these novel technologies into clinical practice is often difficult because fibrotic encapsulation and/or rejection impairs device function after body implantation. Ideally, cells of the host tissue should perceive the surface of the implant being similar to the normal extracellular matrix. Here, we developed an innovative approach to provide implant surfaces with adhesive protein micropatterns. The patterns were designed to promote adhesion of fibroblasts and macrophages by simultaneously suppressing fibrogenic activation of both cell types. In a rat model, subcutaneously implanted silicone pads provided with the novel micropatterns caused 6-fold lower formation of inflammatory giant cells compared with clinical grade, uncoated, or collagen-coated silicone implants. We further show that micropatterning of implants resulted in 2-3-fold reduced numbers of pro-fibrotic myofibroblast by inhibiting their mechanical activation. Our novel approach allows controlled cell attachment to implant surfaces, representing a critical advance for enhanced biointegration of implantable medical devices. PMID:25907047

Majd, Hicham; Scherer, Saja S; Boo, Stellar; Ramondetti, Silvio; Cambridge, Elizabeth; Raffoul, Wassim; Friedrich, Michael; Pittet, Brigitte; Pioletti, Dominique; Hinz, Boris; Pietramaggiori, Giorgio

2015-06-01

193

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

NASA Astrophysics Data System (ADS)

We have applied pulse-shaped biasing to the expanding thermal plasma deposition of hydrogenated amorphous silicon at substrate temperatures ˜200 °C and growth rates around 1 nm/s. Substrate voltage measurements and measurements with a retarding field energy analyzer demonstrate the achieved control over the ion energy distribution for deposition on conductive substrates and for deposition of conductive materials on nonconductive substrates. Presence of negative ions/particles in the Ar-H2-SiH4 plasma is deduced from a voltage offset during biasing. Densification of the material at low Urbach energies is observed at a deposited energy <4.8 eV/Si atom and attributed to an increase in surface mobility of mobile species as well as well as surface atom displacement. The subsequent increase in Urbach energy >4.8 eV/Si atom is attributed to bulk atom displacement in subsurface layers. We make the unique experimental abservation of a decreasing Tauc band gap at increasing total hydrogen concentration—this allows to directly relate the band gap of amorphous silicon to the presence of nanovoids in the material.

Wank, M. A.; van Swaaij, R. A. C. M. M.; Kudlacek, P.; van de Sanden, M. C. M.; Zeman, M.

2010-11-01

194

Controlling the surface roughness of epitaxial SiC on silicon  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

195

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

PubMed Central

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

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

2013-01-01

196

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds  

SciTech Connect

Formation conditions of two types of sodium containing silicon clathrate compounds were determined by the controlled thermal decomposition of sodium monosilicide NaSi under vacuum. The decomposition began at 360 deg. C. Much higher decomposition temperatures and the presence of sodium metal vapor were favorable for the formation of type I clathrate compound Na{sub 8}Si{sub 46}. Type II clathrate compound Na{sub x}Si{sub 136} was obtained as a single phase at a decomposition temperature <440 deg. C under the condition without sodium metal vapor. The type I clathrate compound was decomposed to crystalline Si above 520 deg. C. The type II clathrate compound was thermally more stable, and retained at least up to 550 deg. C in vacuum. - Graphical Abstract: The optimal condition to prepare type II silicon clathrate Na{sub x}Si{sub 136} with minimal contamination of the type I phase is proposed. The starting NaSi should be thermally decomposed below 440 deg. C, and the rapid removal of Na vapor evolved is essentially important.

Horie, Hiro-omi; Kikudome, Takashi; Teramura, Kyosuke [Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan); Yamanaka, Shoji [Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527 (Japan)], E-mail: syamana@hiroshima-u.ac.jp

2009-01-15

197

Large-area silica nanotubes with controllable geometry on silicon substrates  

NASA Astrophysics Data System (ADS)

The synthesis of a highly uniform, large-scale nanoarrays consisting of silica nanotubes above embedded nanohole arrays in silicon substrates is demonstrated. In situ anodized aluminium oxide (AAO) thin film masks on Si substrates were employed, and the nanotubes were fabricated by Ar ion milling through the masks. The geometries of the nanoarrays, including pore diameter, interpore distance and the length of both nanopores and nanotubes could be controlled by the process parameters, which included that the outer pore diameter of silica tube was tuned from ˜80 nm to ˜135 nm while the inner tube diameter from ˜40 nm to ˜65 nm, the interpore distance of the nanotube arrays was from 100 nm to 180 nm and the length of silica tube changed from ˜90 nm to ˜250 nm. The presented nanostructure fabrication method has strong potential for application in intensity and frequency adjustable high luminescence efficiency optoelectronic devices.

Hu, Mingzhe; Yu, Rong; MacManus-Driscoll, Judith L.; Robinson, Adam P.

2009-01-01

198

A Digital PFC Controller without Input Voltage Sensing  

E-print Network

to Fig. 1, in a PFC rectifier the current control objective can be written as: ig= VgIRe, where vg is the rectified line voltage, ig is the low-frequency (average) component of the inductor current, and Re

199

Voltage controlled exchange energies of a two electron silicon double quantum dot with and without charge defects in the dielectric  

E-print Network

Quantum dots are artificial atoms used for a multitude of purposes. Charge defects are commonly present and can significantly perturb the designed energy spectrum and purpose of the dots. Voltage controlled exchange energy in silicon double quantum dots (DQD) represents a system that is very sensitive to charge position and is of interest for quantum computing. We calculate the energy spectrum of the silicon double quantum dot system using a full configuration interaction that uses tight binding single particle wavefunctions. This approach allows us to analyze atomic scale charge perturbations of the DQD while accounting for the details of the complex momentum space physics of silicon (i.e., valley and valley-orbit physics). We analyze how the energy levels and exchange curves for a DQD are affected by nearby charge defects at various positions relative to the dot, which are consistent with defects expected in the metal-oxide-semiconductor system.

Rajib Rahman; Erik Nielsen; Richard P. Muller; Malcolm S. Carroll

2011-12-17

200

Voltage controlled exchange energies of a two electron silicon double quantum dot with and without charge defects in the dielectric  

E-print Network

Quantum dots are artificial atoms used for a multitude of purposes. Charge defects are commonly present and can significantly perturb the designed energy spectrum and purpose of the dots. Voltage controlled exchange energy in silicon double quantum dots (DQD) represents a system that is very sensitive to charge position and is of interest for quantum computing. We calculate the energy spectrum of the silicon double quantum dot system using a full configuration interaction that uses tight binding single particle wavefunctions. This approach allows us to analyze atomic scale charge perturbations of the DQD while accounting for the details of the complex momentum space physics of silicon (i.e., valley and valley-orbit physics). We analyze how the energy levels and exchange curves for a DQD are affected by nearby charge defects at various positions relative to the dot, which are consistent with defects expected in the metal-oxide-semiconductor system.

Rahman, Rajib; Muller, Richard P; Carroll, Malcolm S

2011-01-01

201

13.56 MHz polymer rectifier by printing processes  

NASA Astrophysics Data System (ADS)

Printed electronics have attracted increasing attentions in recent years due to its flexible format, easy process and potentially low cost features. Achieving good performance organic Schottky diode as the key component of a rectifier for printed RFID applications became a critical task. The electrical performances of an organic Schottky diode electrical can be improved by inserting an intermediate layer between the semiconductor and electrode surfaces. This interface plays an important role in improving rectification ratio and lifetime of a polymer diode. In this work, a 13.56MHz rectifier based on a polymer Schottky diode will be demonstrated and a wireless energy transmission built on flexible substrates will be proposed.

Lin, Chang-Yu; Chou, Chia-Hung; Hou, Jack; Chan, Yi-Jen

2007-09-01

202

Interface control of conventional n-type silicon\\/metal by n-channel organic semiconductor  

Microsoft Academic Search

The rectifying and interface state density properties of n-Si\\/violanthrone-79\\/Au metal-diode have been investigated by current–voltage and capacitance–conductance–frequency methods. The ideality factor, barrier height and average series resistance of the diode were found to be 2.07, 0.81eV and 5.04k? respectively. At higher voltages, the organic layer contributes to I–V characteristics of the diode due to space-charge injection into the organic semiconductor

Fahrettin Yakuphanoglu

2010-01-01

203

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

SciTech Connect

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

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

2014-05-21

204

Implementation of Statistical Process Control: Evaluating the Mechanical Performance of a Candidate Silicone Elastomer Docking Seal  

NASA Technical Reports Server (NTRS)

The National Aeronautics and Space Administration has been developing a novel docking system to meet the requirements of future exploration missions to low-Earth orbit and beyond. A dynamic gas pressure seal is located at the main interface between the active and passive mating components of the new docking system. This seal is designed to operate in the harsh space environment, but is also to perform within strict loading requirements while maintaining an acceptable level of leak rate. In this study, a candidate silicone elastomer seal was designed, and multiple subscale test articles were manufactured for evaluation purposes. The force required to fully compress each test article at room temperature was quantified and found to be below the maximum allowable load for the docking system. However, a significant amount of scatter was observed in the test results. Due to the stochastic nature of the mechanical performance of this candidate docking seal, a statistical process control technique was implemented to isolate unusual compression behavior from typical mechanical performance. The results of this statistical analysis indicated a lack of process control, suggesting a variation in the manufacturing phase of the process. Further investigation revealed that changes in the manufacturing molding process had occurred which may have influenced the mechanical performance of the seal. This knowledge improves the chance of this and future space seals to satisfy or exceed design specifications.

Oravec, Heather Ann; Daniels, Christopher C.

2014-01-01

205

Application of artificial intelligence control to the vapor-liquid-solid silicon carbide whisker process  

SciTech Connect

Silicon carbide whiskers have excellent mechanical and chemical properties, making them very desirable as a reinforcement for structural ceramic and other composite materials. Los Alamos has developed a laboratory-scale batch process for producing very high quality SiC whiskers by the vapor-liquid-solid (VLS) method which is an active candidate for technology transfer involving significant scale-up. The process, however, involves quite complex chemical/physical and parametric relationships and has not as yet lent itself successfully to modeling. An expert computer system was therefore developed to facilitate the transfer of this technology to industry. Optimum conditions were determined by relating the many process parameters to product results to establish a set of rules for running the process. These are incorporated in a two-phase expert system designed to guide inexperienced users. In Phase 1, an expert consultant program provides the user with information that enables him to set up the run. This information is incorporated into the rule base that makes up Phase 2 --- the control system. At present, the operator functions as the controller by responding to the decisions of the expert system; automation can be added later. 13 refs., 16 figs.

Shalek, P.D.; Parkinson, W.J.

1989-01-01

206

Through Silicon Via-Based Grid for Thermal Control in 3D Chips  

NASA Astrophysics Data System (ADS)

3D stacked chips have become a promising integration technology for modern systems. The complexity reached in multi-processor systems has increased the communication delays between processing cores, and an effective way to diminish this impact on communication is the 3D integration technology and the use of through-silicon vias (TSVs) for inter-layer communication. However, 3D chips present important thermal issues due to the presence of processing units with a high power density, which are not homogeneously distributed in the stack. Also, the presence of hot-spots creates thermal gradients that impact negatively on the system reliability and relate with the leakage power consumption. Thus, new approaches for thermal control of 3D chips are in great need. This paper discusses the use of a grid and non-uniform placement of TSVs as an effective mechanism for thermal balancing and control in 3D chips. We have modelled the material layers and TSVs mathematically using a detailed calibration phase based on a real 5-tier 3D chip stack, where several heaters and sensors are manufactured to study the heat diffusion. The obtained results show interesting conclusions and new in- sights in the area of thermal modeling and optimization for 3D chips using TSVs.

Ayala, José L.; Sridhar, Arvind; Pangracious, Vinod; Atienza, David; Leblebici, Yusuf

207

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

E-print Network

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 ...

Tang, Sai Chun

208

Method of seismic data enhancement using a phase of rectified trace seismic parameter  

SciTech Connect

The method is described of developing a specific seismic data parameter from seismic trace data, comprising: receiving processed seismic trace data for a selected plane of investigation; rectifying the seismic trace data; producing the Hilbert transform of the rectified trace data; determining the instantaneous phase using Hilbert transformed rectified data; and interpreting geological significance of the plane of investigation using instantaneous phase of the rectified and transformed data.

Stebens, B.; Parsons, R.K.; Baumel, R.T.; Terral, D.K.; Yedlin, M.J.

1986-12-30

209

Performance Evaluation of a Novel Hybrid Multipulse Rectifier for Utility Interface of Power Electronic Converters  

Microsoft Academic Search

This paper presents an improved analysis of a novel programmable power-factor-corrected-based hybrid multipulse power rectifier (PFC-HMPR) for utility interface of power electronic converters. The proposed hybrid multipulse rectifier is composed of an ordinary three-phase six-pulse diode-bridge rectifier (Graetz bridge) with a parallel connection of single-phase switched converters in each three-phase rectifier leg. In this paper, the authors present a complete

Luiz Carlos Gomes de Freitas; M. G. Simoes; Carlos Alberto Canesin

2007-01-01

210

Inward rectifiers and their regulation by endogenous polyamines.  

PubMed

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

Baronas, Victoria A; Kurata, Harley T

2014-01-01

211

Seismic triggering by rectified diffusion in geothermal systems  

Microsoft Academic Search

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

Bradford Sturtevant; Hiroo Kanamori; Emily E. Brodsky

1996-01-01

212

35 GHz integrated circuit rectifying antenna with 33 percent efficiency  

NASA Technical Reports Server (NTRS)

A 35 GHz integrated circuit rectifying antenna (rectenna) has been developed using a microstrip dipole antenna and beam-lead mixer diode. Greater than 33 percent conversion efficiency has been achieved. The circuit should have applications in microwave/millimeter-wave power transmission and detection.

Yoo, T.-W.; Chang, K.

1991-01-01

213

Inward rectifiers and their regulation by endogenous polyamines  

PubMed Central

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

Baronas, Victoria A.; Kurata, Harley T.

2014-01-01

214

Design aspects of paralleled three-phase DCM boost rectifiers  

Microsoft Academic Search

The interleaved operation of paralleled boost rectifiers reduces the amplitude of the input current ripple and increases its effective frequency. As a consequence, the size and volume of the input EMI filter can be reduced. This work provides a detailed analysis of the fundamental component of the input current ripple of the interleaved system along with curves that facilitate the

Peter M. Barbosa; Fred C. Lee

1999-01-01

215

Power MOSFET Basics Vrej Barkhordarian, International Rectifier, El Segundo, Ca.  

E-print Network

Power MOSFET Basics Vrej Barkhordarian, International Rectifier, El Segundo, Ca. Discrete power MOSFETs employ semiconductor processing techniques that are similar to those of today's VLSI circuits in VLSI devices. The metal oxide semiconductor field effect transistor (MOSFET) is based on the original

Paderborn, Universität

216

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

217

Performance of the Wells self-rectifying air turbine  

Microsoft Academic Search

Analytical and experimental studies of the effect of geometric and aerodynamic variables on the performance of the Wells self-rectifying air turbine are presented in this paper. Two approaches to the prediction of the Wells turbine performance are described, both of which are based on the two dimensional cascade theory and isolated aerofoil data. Experimental results are based on the investigations

S. Raghunathan; C. P. Tan; O. O. Ombaka

1985-01-01

218

Measurement of the Current Generated by a Rectifier Photoelectric Cell  

Microsoft Academic Search

CAMPBELL and Freeth1 have described a method of measuring the current generated by a rectifier cell in such a way as to reduce greatly the disturbing effect of the internal leakage which occurs in these cells. This varies with temperature and intensity of illumination and may cause large curvature of the light-current characteristic in strong light. This method consists in

H. H. Poole; W. R. G. Atkins

1934-01-01

219

The spectral sensitivity of selenium rectifier photoelectric cells  

Microsoft Academic Search

It is shown that the spectral distribution curve of sensitivity of the selenium rectifier cell is determined by the external-circuit resistance, the output and the temperature; consequently the course of the {sensitivity, output} curve is determined by the quality of the incident radiation, the external-circuit resistance and the temperature. Further, the observed temperature coefficient of sensitivity is determined by the

G P Barnard

1939-01-01

220

Controllable shrinking of inverted-pyramid silicon nanopore arrays by dry-oxygen oxidation  

NASA Astrophysics Data System (ADS)

A novel and simple technique for the controllable shrinkage of inverted-pyramid silicon (Si) nanopore arrays is reported. The Si nanopore arrays with sizes from 60 to 150 nm, made using a combination of dry and wet etching, were shrunk to sub 10 nm, or even closed, using direct dry-oxygen oxidation at 900?° C. The shrinkage process of the pyramidal nanopore induced by oxidation was carefully modeled and simulated. The simulation was found to be in good agreement with the experimental data within most of the oxidation time range. Using this method, square nanopore arrays with an average size of 30 nm, and rectangular nanopores and nanoslits with feature sizes as small as 8 nm, have been obtained. Furthermore, focused ion beam cutting experiments revealed that the inner structure of the nanopore after the shrinkage kept its typical inverted-pyramid shape, which is of importance in many fields such as biomolecular sensors and ionic analogs of electronic devices, as well as nanostencils for surface nano-patterning.

Deng, Tao; Chen, Jian; Li, Mengwei; Wang, Yifan; Zhao, Chenxu; Zhang, Zhonghui; Liu, Zewen

2013-12-01

221

Design simplification of a small nuclear reactor for large-diameter neutron transmutation doping silicon using control rods  

Microsoft Academic Search

A design concept for a small nuclear reactor for neutron transmutation doping silicon (NTD-Si) using a Pressurized Water Reactor (PWR) full-length fuel assembly was proposed in our previous work. The excess reactivity was suppressed by a combination of Gd2O3 and soluble boron, which results in a flatter flux profile over the core than with control rod insertion; however, the soluble

Munkhbat Byambajav; Toru Obara

2012-01-01

222

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

SciTech Connect

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

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

2014-01-01

223

Functional Nanoscale Electronic Devices Assembled Using Silicon Nanowire Building Blocks  

Microsoft Academic Search

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

Yi Cui; Charles M. Lieber

2001-01-01

224

Photovoltaic Measurements in Single-Nanowire Silicon Solar Cells  

E-print Network

Photovoltaic Measurements in Single-Nanowire Silicon Solar Cells Michael D. Kelzenberg, Daniel B Single-nanowire solar cells were created by forming rectifying junctions in electrically contacted vapor-voltage measurements were made under simulated Air Mass 1.5 global illumination. Photovoltaic spectral response

Atwater, Harry

225

A novel three-phase utility interface minimizing line current harmonics of high-power telecommunications rectifier modules  

Microsoft Academic Search

Based on the combination of a three-phase diode bridge and a DC\\/DC boost converter, a new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed. It can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors. The application could be, e.g., for feeding the DC link of a telecommunications power

Johann W. Kolar; Franz C. Zach

1997-01-01

226

Low Voltage and Current Stress ZVZCS Full Bridge DC–DC Converter Using Center Tapped Rectifier Reset  

Microsoft Academic Search

An improved zero-voltage and zero-current-switching (ZVZCS) full bridge dc-dc converter is proposed based on phase shift control. With an auxiliary center tapped rectifier at the secondary side, an auxiliary voltage source is applied to reset the primary current of the transformer winding. Therefore, zero-voltage switching for the leading leg switches and zero-current switching for the lagging leg switches can be

Xinke Wu; Xiaogao Xie; Chen Zhao; Zhaoming Qian; Rongxiang Zhao

2008-01-01

227

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

E-print Network

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). ...

Choi, Dongwon, 1973-

2004-01-01

228

Inward-rectifier chloride currents in Reissner’s membrane epithelial cells  

PubMed Central

Sensory transduction in the cochlea depends on regulated ion secretion and absorption. Results of whole-organ experiments suggested that Reissner’s membrane may play a role in the control of luminal Cl?. We tested for the presence of Cl? transport pathways in isolated mouse Reissner’s membrane using whole-cell patch clamp recording and gene transcript analyses using RT-PCR. The current-voltage (I-V) relationship in the presence of symmetrical NMDG-Cl was strongly inward-rectifying at negative voltages, with a small outward current at positive voltages. The inward-rectifying component of the I-V curve had several properties similar to those of the ClC-2 Cl? channel. It was stimulated by extracellular acidity and inhibited by extracellular Cd2+, Zn2+, and intracellular ClC-2 antibody. Channel transcripts expressed include ClC-2, Slc26a7 and ClC-Ka, but not Cftr, ClC-1, ClCa1, ClCa2, ClCa3, ClCa4, Slc26a9, ClC-Kb, Best1, Best2, Best3 or the beta-subunit of ClC-K, barttin. ClC-2 is the only molecularly-identified channel present that is a strong inward rectifier. This study is the first report of conductive Cl? transport in epithelial cells of Reissner’s membrane and is consistent with an important role in endolymph anion homeostasis. PMID:20226170

Kim, Kyunghee X.; Marcus, Daniel C.

2011-01-01

229

SLiM-cut thin silicon wafering with enhanced crack and stress control  

Microsoft Academic Search

The 'Stress induced LIft-off Method' (SLiM-Cut) is a kerf-free method for thin silicon fabrication, being developed at imec for photovoltaic applications [1]. This method makes particularly efficient use of bulk material, thus cutting down the Si cost. SLIM-Cut uses a metallic layer on top of thick silicon substrate. The bonding is achieved at high temperature. Quenching the assembly down to

Jan Vaes; Alex Masolin; Amaia Pesquera; Frédéric Dross

2010-01-01

230

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

NASA Technical Reports Server (NTRS)

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

Powell, J. Anthony (inventor)

1991-01-01

231

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

232

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

NASA Astrophysics Data System (ADS)

This work demonstrates how to improve the size distribution of silicon nanocrystals (Si-NCs) synthesized in a remote plasma, in which the flow dynamics and the particular chemistry initially resulted in the formation of small (2–10 nm) and large (50–120 nm) Si-NCs. Plasma consists of two regions: an axially expanding central plasma beam and a background region around the expansion. Continuum fluid dynamics simulations demonstrate that a significant mass flow occurs from the central beam to the background region. This mass flow can be gradually reduced upon confinement of the central beam, preventing the mass transport to the background region. Transmission electron microscopy and Raman spectroscopy analyses demonstrate that the volume fraction of large Si-NCs decreases from ˜77% to below 45% in parallel with the decrease of mass flow to the background region upon confinement, which indicates that large Si-NCs are synthesized in the background and small Si-NCs are synthesized in the central beam. Spatially resolved ion flux analyses demonstrate that the ions are localized in the central beam despite the mass flow to the background, indicating that the formation of small Si-NCs is governed by ion-assisted growth while the formation of large Si-NCs is governed by radical-neutral-assisted growth in the absence of ions. According to these observations, a better uniformity in the size distribution of Si-NCs can be obtained by creating a more uniform plasma flow and controlling the density of plasma species in the plasma.

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

2015-02-01

233

Development of a Thermal Rectifier Usable at High Temperature  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

234

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

PubMed Central

Tunability is a desirable property of microring resonators to facilitate superior performance. Using light to control light, we present an alternative simple approach to tuning the extinction ratio (ER) and Q-factor of silicon microring resonators based on optical forces. We design an opto-mechanical tunable silicon microring resonator consisting of an add-drop microring resonator and a control-light-carrying waveguide (“controlling” waveguide). One of the two bus waveguides of the microring resonator is a deformable nanostring put in parallel with the “controlling” waveguide. The tuning mechanism relies on the optical force induced deflection of suspended nanostring, leading to the change of coupling coefficient of microring and resultant tuning of ER and Q-factor. Two possible geometries, i.e. double-clamped nanostring and cantilever nanostring, are studied in detail for comparison. The obtained results imply a favorable structure with the microring positioned at the end of the cantilever nanostring. It features a wide tuning range of ER from 5.6 to 39.9?dB and Q-factor from 309 to 639 as changing the control power from 0 to 1.4?mW. PMID:24958225

Long, Yun; Wang, Jian

2014-01-01

235

Gravure printed organic rectifying diodes operating at high frequencies  

Microsoft Academic Search

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

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

2009-01-01

236

Optimization design of rectifier transformer coil based on genetic algorithm  

Microsoft Academic Search

Coil design has played an important role in design process of rectifier transformer with high-voltage, low-voltage and adjusting-voltage windings. This paper presents its optimal mathematical model, and analyzes its target functions, decision-making variables and constraints .In order to facilitate the optimization process, the constraints are disposed of with adding a penalty function or amending method. We optimize the model using

Wang Zhurong; Ciii Duwu; Zhou Hongfang; Yu Gang

2004-01-01

237

Rectifying electrical noise with an ionic-organic ratchet.  

PubMed

Electronic ratchets can rectify AC signals that are extracted from unpredictable energy fluctuations. A device is presented with ratchet-like current-voltage characteristics, which delivers record high electrical currents of 2.6 and 1.7 ?A when driven with an AC signal of square wave and random amplitude, respectively. The device is based on a poly(3-hexylthiophene-2,5-diyl):salt blend, which acquires rectification properties after a voltage stress in a transistor configuration. PMID:25676926

Mikhnenko, Oleksandr V; Collins, Samuel D; Nguyen, Thuc-Quyen

2015-03-01

238

Low forward drop JBS rectifiers fabricated using submicron technology  

Microsoft Academic Search

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

Manoj Mehrotra; B. Jayant Baliga

1994-01-01

239

Very low forward drop JBS rectifiers fabricated using submicron technology  

Microsoft Academic Search

An increase in the efficiency of power supplies for ICs requires development of output rectifiers with low on-state voltage drop and low reverse leakage current. At present Schottky barried diodes (SBD) with an on-state voltage drop of 0.55V are used. The On-state voltage drop can be reduced by decreasing the metal-semiconductor barrier height (4~) at the expense of increased reverse

Manoj Mehrotra; B. J. Baliga

1993-01-01

240

Single-Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications  

SciTech Connect

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance. To understand the power flow through the system this paper presents a novel approach to the system model and the impact of different control parameters on the load power. The implementation of an active front-end rectifier on the grid side for power factor control and voltage boost capability for load power regulation is also discussed.

Chinthavali, Madhu Sudhan [ORNL] [ORNL; Onar, Omer C [ORNL] [ORNL; Miller, John M [ORNL] [ORNL; Tang, Lixin [ORNL] [ORNL

2013-01-01

241

Layer-by-Layer Assembly of Rectifying Junctions in and on Metal Nanowires Nina I. Kovtyukhova,*,, Benjamin R. Martin, Jeremiah K. N. Mbindyo, Peter A. Smith,|  

E-print Network

Versity Park, PennsylVania 16802 ReceiVed: March 7, 2001; In Final Form: June 23, 2001 Alumina membranes that can function as rectifiers, transistors, and switches.2 One of the best recognized barriers to using in the cylindrical pores of an alumina or polycarbonate membrane. By controlling the charge passed in each plating

242

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

PubMed Central

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

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

2013-01-01

243

Microcomputer controlled soft start of motor  

NASA Astrophysics Data System (ADS)

Improving the starting characteristics of a motor is an important part of the motor control. An intelligent soft starting technique was adopted in the starter and used in the present study because of its many advantages compared with conventional starting processes. The core of the soft starter was a single chip (Atmel 8098), its soul was the software and its control object was a Silicon Controlled Rectifier (SCR). The starter achieved not only current-limit starting, but also closed-loop control with a stator current detection circuit. In conclusion, as a result of digital control, starting characteristic can be conveniently chosen according to the load. In addition the starter is of small size, and starting is smooth and reliable due to current feedback.

Gao, Miao; Wang, Yanpeng; Li, Shian

2005-12-01

244

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.

245

Silicon photo-multiplier radiation hardness tests with a beam controlled neutron source  

NASA Astrophysics Data System (ADS)

Radiation hardness tests were performed at the Frascati Neutron Generator on silicon Photo-Multipliers that were made of semiconductor photon detectors built from a square matrix of avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated, integrating up to 7×10 10 1-MeV-equivalent neutrons per cm 2. Detector performance was recorded during the neutron irradiation, and a gradual deterioration of their properties began after an integrated fluence of the order of 10 8 1-MeV-equivalent neutrons per cm 2 was reached.

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

2010-11-01

246

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

E-print Network

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

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

2010-06-08

247

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

NASA Astrophysics Data System (ADS)

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

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

2010-07-01

248

High reliability megawatt transformer/rectifier  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

249

Detection of epileptic seizures from single lead ECG by means of phase rectified signal averaging.  

PubMed

Epileptic seizures have a clear effect on the regulatory mechanisms of the autonomic nervous system, especially on the cardiac and respiratory controls. Changes in heart rate and respiration are well known to occur around the onset of the seizure. This paper studies the ECG signals recorded from patients suffering from epilepsy, whose ages ranged from 3 to 48 years. Both focal and generalized seizures are considered. Changes in cardiorespiratory control and coupling, are assessed using phase rectified signal averaging (PRSA), which is a technique that finds quasi-periodicities in noisy and non-stationary signals. A positive predictive value (PPV) of 86.21% with sensitivity of 100% was obtained for focal seizures, and a PPV of 84.3% with 93.1% sensitivity for generalized seizures. PMID:25570816

Varon, Carolina; Caicedo, Alexander; Jansen, Katrien; Lagae, Lieven; Van Huffel, Sabine

2014-01-01

250

Controlled line shaped electron beam for silicon zone melting recrystallization on float glass substrates  

Microsoft Academic Search

A line shaped electron beam system for the zone melting recrystallization (ZMR) of thick silicon films on float glass substrates is described. The low thermal stability of the glass requires a rapid regulated zone heating. The electron beam system allows the ZMR in a continuous scan without pulsing. The setup consists of the tungsten wire with a Pierce reflector as

F. Gromball; C. Groth; J. Mueller

2005-01-01

251

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

Microsoft Academic Search

After the pioneering investigations into graphene-based electronics at Georgia Tech (GT), 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 invaluable material for fundamental two-dimensional electron gas physics showing that only EG is on route to

W. A. de Heer; C. Berger; M. Ruan; M. Sprinkle; X. Li; Y. Hu; B. Zhang; J. Hankinson; E. Conrad

2011-01-01

252

Bandpass integrated Bragg gratings in silicon-on-insulator with well-controlled amplitude and phase responses.  

PubMed

Bandpass filters with square shape amplitude responses and well-controlled dispersion characteristics are achieved by accurate apodization of Bragg grating structures in silicon-on-insulator waveguides. For these devices, precise tailoring of their frequency response typically requires low coupling coefficients and relatively long on-chip propagation lengths. These challenges are addressed by implementing apodization by phase-modulation and using wider strip waveguides to reduce phase noise. This design approach is demonstrated with a dispersion-less narrowband filter and a chirped bandpass filter. PMID:25723420

Simard, Alexandre D; Strain, Michael J; Meriggi, Laura; Sorel, Marc; LaRochelle, Sophie

2015-03-01

253

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

254

Primary Structure and Characterization of a Small-Conductance Inwardly Rectifying Potassium Channel from Human Hippocampus  

Microsoft Academic Search

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

Francois Perier; Carolyn M. Radeke; Carol A. Vandenberg

1994-01-01

255

Circuit topologies for single-phase voltage-doubler boost rectifiers  

Microsoft Academic Search

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

John C. Salmon

1993-01-01

256

A novel passive waveshaping method for single-phase diode rectifiers  

Microsoft Academic Search

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.

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

1990-01-01

257

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

NASA Astrophysics Data System (ADS)

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.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. Electronic supplementary information (ESI) available: Additional SEM images, photographs of seed solution and XRD peaks and XPS. See DOI: 10.1039/c3nr03694d

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

2014-03-01

258

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

PubMed Central

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

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

1996-01-01

259

Rectifying calibration error of Goldmann applanation tonometer is easy!  

PubMed Central

Purpose: Goldmann applanation tonometer (GAT) is the current Gold standard tonometer. However, its calibration error is common and can go unnoticed in clinics. Its company repair has limitations. The purpose of this report is to describe a self-taught technique of rectifying calibration error of GAT. Materials and Methods: Twenty-nine slit-lamp-mounted Haag-Streit Goldmann tonometers (Model AT 900 C/M; Haag-Streit, Switzerland) were included in this cross-sectional interventional pilot study. The technique of rectification of calibration error of the tonometer involved cleaning and lubrication of the instrument followed by alignment of weights when lubrication alone 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

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

260

Inwardly rectifying whole cell potassium current in human blood eosinophils  

PubMed Central

Membrane currents were studied in single human blood eosinophils using the whole cell voltage clamp technique. The whole cell current-voltage relationship exhibited rectification about the membrane potential which followed the potassium equilibrium potential when [K+]o was raised. Elevation of [K+]o considerably potentiated inward current amplitude, and in some cells channel activity was discernible in the whole cell membrane current recordings. The single channel conductance was 24 ± 1 pS ([K+]o, 100 mm [K+]i, 140 mm), and eosinophils were found to have as few as three, and on average twenty, inward rectifier channels each. The inward current was inhibited in a voltage-dependent manner by extracellular cations in order of potency Ba2+ > Cs+ > Na+. Intracellular acidification inhibited while alkalization augmented the inward current. Mg2+ contributed to rectification as dialysis with nominally Mg2+-free pipette solution was associated with an increase in the outward current during membrane polarization. By reverse transcription-polymerase chain reaction (RT-PCR) using suitable primers on human eosinophil mRNA, an inward rectifier channel, Kir2.1, was identified, which is known from expression studies to have very similar properties to those found in this study. Superoxide anion production or its stimulation by phorbol 12-myristate 13-acetate (PMA) was not significantly affected by depolarization with 140 mm [K+]o, or by 1 mm BaCl2. It is concluded that the single channel currents and the whole cell current rectification observed in human blood eosinophils resulted from the presence of an inwardly rectifying potassium channel, probably Kir2.1. PMID:9490857

Tare, M; Prestwich, S A; Gordienko, D V; Parveen, S; Carver, J E; Robinson, C; Bolton, T B

1998-01-01

261

Rectified Brownian motion and kinesin motion along microtubules  

NASA Astrophysics Data System (ADS)

The mechanism of rectified Brownian movement is used to analyze measured data for kinesin motion along microtubules. A key component of the mechanism is the diffusive movement of the microtubule binding heads of kinesin during the adenosine triphosphate (ATP) cycle. The first-passage time distribution for this step is analyzed in detail and is shown to be responsible for observed load-velocity profiles. The ATPase activity of the kinesin heads is that of a nucleotide switch and not that of a direct chemomechanical energy converter. Experimental data acquisition, rate constants, and alternative explanations are discussed. The mechanism described in this paper is fundamental to the nanobiology of intracellular processes.

Fox, Ronald F.; Choi, Mee Hyang

2001-05-01

262

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

DOEpatents

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

Weiner, Kurt H. (San Jose, CA)

2001-01-01

263

Control of band structure of van der Waals heterostructures: Silicene on ultrathin silicon nanosheets  

NASA Astrophysics Data System (ADS)

The geometric and electronic properties of silicene on doping ultrathin silicon nanosheet were performed using dispersion-corrected density-functional theory. The results show that the substrates modify the electronic properties of silicene due to the difference of charge population between the two sublattices. A sizable band gap is created at the Dirac point, which could be widened by bias voltage. It is theorized that the hetero-structures could provide a viable route to silicene-based electronic devices.

Li, Shuang; Wu, Yifeng; Liu, Wei; Zhao, Yonghao

2014-08-01

264

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

SciTech Connect

Superlattices containing 3?nm thick silicon rich silicon nitride sublayers and 3?nm and 10?nm thick SiO{sub 2} barriers were prepared by plasma enhanced chemical vapor deposition. Despite the as-prepared samples represented a well-kept multilayer structure with smooth interfaces, the high temperature annealing resulted in the total destruction of multilayer structure in the samples containing 3?nm SiO{sub 2} barriers. Energy-filtered transmission electron microscopy images of these samples indicated a silicon nanoclusters formation with sizes of 2.5–12.5?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.

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

265

Rapid thermal processing of high-efficiency silicon solar cells with controlled in-situ annealing  

SciTech Connect

Silicon solar cell efficiencies of 17.1%, 16.4%, 14.8%, and 14.9% have been achieved on FZ, Cz, multicrystalline (mc-Si), and dendritic web (DW) silicon, respectively, using simplified, cost-effective rapid thermal processing (RTP). These represent the highest reported efficiencies for solar cells processed with simultaneous front and back diffusion with no conventional high-temperature furnace steps. Appropriate diffusion temperature coupled with the added in-situ anneal resulted in suitable minority-carrier lifetime and diffusion profiles for high-efficiency cells. The cooling rate associated with the in-situ anneal can improve the lifetime and lower the reverse saturation current density (J{sub 0}), however, this effect is material and base resistivity specific. PECVD antireflection (AR) coatings provided low reflectance and efficient front surface and bulk defect passivation. Conventional cells fabricated on FZ silicon by furnace diffusions and oxidations gave an efficiency of 18.8% due to greater short wavelength response and lower J{sub 0}.

Doshi, P.; Rohatgi, A.; Ropp, M.; Chen, Z. [Georgia Institute of Technology, Atlanta, GA (United States). Univ. Center of Excellence for Photovoltaics Research and Education; Ruby, D. [Sandia National Labs., Albuquerque, NM (United States); Meier, D.L. [EBARA Solar, Inc., Large, PA (United States)

1995-01-01

266

Chemical control over the formation and reactivity of ultra-thin films and amino-terminated layers on silicon  

NASA Astrophysics Data System (ADS)

The physical-chemical properties of several interfacial systems of technological relevance are investigated, having as a common goal the elucidation of strategies towards their atomic- and molecular-level control. Such systems can be classified in three groups: (i) ultra-thin films deposited using metalorganic precursors, (ii) metalorganic monolayers on silicon, and (iii) amine-functionalized silicon surfaces. Experimental, theoretical and chemometric methods are conveniently combined to gain a solid understanding of these systems. The ultra-thin films under investigation are titanium carbonitride (TiNC) and hafnium oxide (HfO2). Since these films may serve as substrates for deposition of other materials in circuit components, their surface chemistry needs to be understood and controlled in order to facilitate further deposition steps. The surface of a TiCN film is transformed to titanium nitride (TiN) through nitridation with ammonia; this compositional change can be reversed by the partial decomposition of ethylene molecules on the surface. The surface reactivity is observed to depend on the film composition, and therefore the method described above serves to reversibly tune the reactivity of Ti-based films. As for HfO2 films, it is found that the deposition temperature affects the degree of crystallinity of the films, which in turn affects their surface chemistry. Thus, together with a control of the composition, it is found that the reactivity of a film can be controlled precisely by controlling the crystallinity. The investigation of metalorganic monolayers on silicon surfaces was motivated by the need for understanding the first steps of metalorganic-based deposition of films, which is usually characterized by a heavy presence of contaminants that degrade the film properties. Through a combination of vibrational (infrared) spectroscopy and theoretical methods, a feasible pathway for the adsorption and decomposition of Ti[N(CH3)2]4 is found. This pathway starts with the ligand-mediated attachment of the precursor (through a N atom), followed by dissociation of a metal-ligand bond. In addition, the C-H bond is broken, possibly forming Si-C bonds and causing carbon incorporation. This model is found to be rather robust and to adequately describe other types of metalorganic precursors. It allows establishing a generalized model able to explain the success or failure of a metalorganic precursor chemistry for film deposition. Finally, amine-functionalized silicon surfaces are considered as prototypical systems where the spatial distribution of adsorbates and the control over the reactivity of surface sites can be investigated. The spatial distribution of molecules is investigated at the atomic level by considering the saturation of a Si(100) surface with NH3. It is found that the distribution of (Si)NH2 species can be controlled thermally and, more importantly, that during thermal decomposition N inserts into the substrate in manners that minimize the arising strain. When the surface is covered with NH 3 or with organic amines, its chemical behavior is determined by the basicity of the molecule functionalizing the surface. The precise tuning of the reactivity (basicity) of surface sites opens the doors for highly controllable, selective reactions. Although these results are obtained from rather fundamental grounds, their interpretation is often translated into manners in which technological applications can be improved. Further directions worth exploring emanated from this work are outlined and discussed. Ultimately, this work intends to highlight the current importance of surface physical chemistry in the continuous development of modern society through the improvement of its technology.

Rodriguez-Reyes, Juan Carlos F.

267

Silicon nanowires with controlled sidewall profile and roughness fabricated by thin-film dewetting and metal-assisted chemical etching.  

PubMed

This paper presents a non-lithographic approach to generate wafer-scale single crystal silicon nanowires (SiNWs) with controlled sidewall profile and surface morphology. The approach begins with silver (Ag) thin-film thermal dewetting, gold (Au) deposition and lift-off to generate a large-scale Au mesh on Si substrates. This is followed by metal-assisted chemical etching (MacEtch), where the Au mesh serves as a catalyst to produce arrays of smooth Si nanowires with tunable taper up to 13°. The mean diameter of the thus fabricated SiNWs can be controlled to range from 62 to 300 nm with standard deviations as small as 13.6 nm, and the areal coverage of the wire arrays can be up to 46%. Control of the mean wire diameter is achieved by controlling the pore diameter of the metallic mesh which is, in turn, controlled by adjusting the initial thin-film thickness and deposition rate. To control the wire surface morphology, a post-fabrication roughening step is added to the approach. This step uses Au nanoparticles and slow-rate MacEtch to produce rms surface roughness up to 3.6 nm. PMID:23644697

Azeredo, B P; Sadhu, J; Ma, J; Jacobs, K; Kim, J; Lee, K; Eraker, J H; Li, X; Sinha, S; Fang, N; Ferreira, P; Hsu, K

2013-06-01

268

Role of gate oxide thickness in controlling short channel effects in polycrystalline silicon thin film transistors  

NASA Astrophysics Data System (ADS)

The drain bias induced threshold voltage variation in short channel (L =0.4 ?m) polycrystalline silicon thin-film transistors (TFTs), with different gate oxide thicknesses, is investigated with combined experimental measurements and numerical simulations. Drain-induced barrier lowering (DIBL) and floating body effects (FBEs), triggered by impact ionization, are the main causes of such variations. However, the effects are counterbalancing, with a reducing oxide thickness reducing DIBL, while, at the same time, increasing the relative impact of the FBE. Hence, drain bias induced threshold voltage changes, when normalized by oxide thickness, are independent of the gate oxide thickness in these TFTs.

Valletta, A.; Gaucci, P.; Mariucci, L.; Pecora, A.; Cuscunà, M.; Maiolo, L.; Fortunato, G.; Brotherton, S. D.

2009-07-01

269

Controlling surface states and photoluminescence of porous silicon by low-energy-ion irradiation  

NASA Astrophysics Data System (ADS)

Porous silicon (PS) was irradiated by three kinds of low-energy ions with different chemical activity, namely argon ions, nitrogen ions and oxygen ions. The chemical activity of ions has significant effect on the surface states and photoluminescence (PL) properties of PS, The photoluminescence quenching after argon ions and nitrogen ions irradiation is ascribed to the broken Si-Si bonds, while the PL recovery is attributed to the oxidation of Si-H back bonds. Oxygen ions irradiation leads to the formation of a SiO x layer with oxygen defects and PS shows different PL evolution than PS irradiated by argon ions and nitrogen ions.

Du, X. W.; Jin, Y.; Zhao, N. Q.; Fu, Y. S.; Kulinich, S. A.

2008-02-01

270

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

Microsoft Academic Search

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

Xing-Yuan Li; O. P. Malik

1994-01-01

271

Efficient Design of Rectifying Antennas for Low Power Detection Vlad Marian  

E-print Network

Efficient Design of Rectifying Antennas for Low Power Detection Vlad Marian 1 , Cyrille Menudier 2, France Abstract -- This article is dedicated to the design of rectifying antenna for wireless energy an important non-linear behavior with such power levels, specific design guidelines must be respected in order

Paris-Sud XI, Université de

272

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

E-print Network

-electrode piezoelectric transducer to be rectified with reduced output ripple. The rectifier has a measured power-based energy harvesting systems use a piezoelectric transducer as an AC power source, whose output voltage must efficiency and its equivalent loading on the piezoelectric transducer largely determine the total power

Hurst, Paul J.

273

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

E-print Network

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

Lehn, Peter W.

274

Comparative Investigation on Different Topologies of Integrated Magnetic Structures for Current-doubler Rectifier  

Microsoft Academic Search

The advancement of technology requires that power supplies have high efficiency and high power density. The current doubler rectifier has been presented as a solution to decrease the transformer secondary power loss and increase the power efficiency. In this paper, the unified equivalent coupled inductor circuit models are constructed for different current doubler rectifier integrated magnetic structures. Based on the

Hua Zhou; Thomas X. Wu; Issa Batarseh; Khai D. T. Ngo

2007-01-01

275

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

276

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

PubMed

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

Adam, Tijjani; Hashim, U

2015-05-15

277

Gate tunable graphene-silicon Ohmic/Schottky contacts  

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

278

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

279

Covalent and Stable CuAAC Modification of Silicon Surfaces for Control of Cell Adhesion.  

PubMed

Stable primary functionalization of metal surfaces plays a significant role in reliable secondary attachment of complex functional molecules used for the interfacing of metal objects and nanomaterials with biological systems. In principle, this can be achieved through chemical reactions either in the vapor or liquid phase. In this work, we compared these two methods for oxidized silicon surfaces and thoroughly characterized the functionalization steps by tagging and fluorescence imaging. We demonstrate that the vapor-phase functionalization only provided transient surface modification that was lost on extensive washing. For stable surface modification, a liquid-phase method was developed. In this method, silicon wafers were decorated with azides, either by silanization with (3-azidopropyl)triethoxysilane or by conversion of the amine groups of an aminopropylated surface by means of the azido-transfer reaction. Subsequently, D-amino acid adhesion peptides could be immobilized on the surface by use of Cu(I) -catalyzed click chemistry. This enabled the study of cell adhesion to the metal surface. In contrast to unmodified surfaces, the peptide-modified surfaces were able to maintain cell adhesion during significant flow velocities in a microflow reactor. PMID:25737226

Vutti, Surendra; Buch-Månson, Nina; Schoffelen, Sanne; Bovet, Nicolas; Martinez, Karen L; Meldal, Morten

2015-03-23

280

A Vertical Diffusion Scheme to estimate the atmospheric rectifier effect  

NASA Astrophysics Data System (ADS)

The magnitude and spatial distribution of the carbon sink in the extratropical Northern Hemisphere remain uncertain in spite of much progress made in recent decades. Vertical CO2 diffusion in the planetary boundary layer (PBL) is an integral part of atmospheric CO2 transport and is important in understanding the global CO2 distribution pattern, in particular, the rectifier effect on the distribution [Keeling et al., 1989; Denning et al., 1995]. Attempts to constrain carbon fluxes using surface measurements and inversion models are limited by large uncertainties in this effect governed by different processes. In this study, we developed a Vertical Diffusion Scheme (VDS) to investigate the vertical CO2 transport in the PBL and to evaluate CO2 vertical rectification. The VDS was driven by the net ecosystem carbon flux and the surface sensible heat flux, simulated using the Boreal Ecosystem Productivity Simulator (BEPS) and a land surface scheme. The VDS model was validated against half-hourly CO2 concentration measurements at 20 m and 40 m heights above a boreal forest, at Fraserdale (49°52'29.9''N, 81°34'12.3''W), Ontario, Canada. The amplitude and phase of the diurnal/seasonal cycles of simulated CO2 concentration during the growing season agreed closely with the measurements (linear correlation coefficient (R) equals 0.81). Simulated vertical and temporal distribution patterns of CO2 concentration were comparable to those measured at the North Carolina tower. The rectifier effect, in terms of an annual-mean vertical gradient of CO2 concentration in the atmosphere that decreases from the surface to the top of PBL, was found at Fraserdale to be about 3.56 ppmv. Positive covariance between the seasonal cycles of plant growth and PBL vertical diffusion was responsible for about 75% of the effect, and the rest was caused by covariance between their diurnal cycles. The rectifier effect exhibited strong seasonal variations, and the contribution from the diurnal cycle was mostly confined to the surface layer (less than 300 m).

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

2004-02-01

281

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

PubMed

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

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

2015-01-15

282

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

SciTech Connect

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

Leahu, G. L., 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

283

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

284

Ordered Mesostructured CdS Nanowire Arrays with Rectifying Properties  

PubMed Central

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

2009-01-01

285

Theoretical analysis of a rectifying gap junction model.  

PubMed

Based on the experimental observations, an electrical circuitry model for a rectifying gap junction was developed in previous work. In order to show the physiological function for each element in the model, a theoretical analysis is carried out in this report. The results indicate that the gap junctional capacitance Cj newly introduced into the model plays a major role in determining the duration increase, the peak attenuation, and the peak delay on the postmembrane action potential. Also, a comparison between the newly proposed model and the widely accepted kinetic model by Giaume is made. The results show that the electrical circuitry model can not only describe the characteristics of Giaume's model but also allow the interpretation of some experimental phenomena that were not reflected in other gap junctional models. PMID:10892251

Hu, X L; Zhang, Y T; Bao, J L

2000-06-01

286

Slope stability of rectify coal waste embankments on mining areas  

SciTech Connect

The paper is of a theoretical and experimental character, focusing on the results of field tests on the load-bearing capacity and stability of high (> 20m.) transportation embankments rectified with coal waste. The embankments are located in industrial areas subjected to the intense impact of underground mining. Such phenomena are also accompanied by essential changes in the water conditions of the subsoil. The results of model tests by SIR geo-radar used to non-damaging estimation of the suffusion occurring in the embankment constructed on non-waste materials are discussed. The numerical assessment of the filtration process has been based on the MFE and MBE programs, which are extended calculation procedures enabling the overall estimation of the redistribution of all the stress-strain components in the structure, in consideration of any hypothesis of the boundary state.

Klossek, C.

1999-07-01

287

A study of the factors which control the efficiency of ion-implanted silicon solar cells  

NASA Technical Reports Server (NTRS)

The objective of this work was to determine experimentally the ion-implantation parameters and furnace annealing conditions required to produce high-efficiency solar cells. A comprehensive experimental study was conducted in which the optimum ion-implantation parameters were found by a systematic variation of the implant parameters followed by detailed studies of solar-cell devices. Two furnace heat-treatment techniques were found which effectively anneal the implanted layers and at the same time preserve or improve the diffusion length in the bulk silicon. Detailed characteristics of both the junction and bulk properties of solar cells fabricated over the spectrum of implant parameters are discussed. Optimized implant parameters and annealing conditions were found which allow for the fabrication of 14-15-percent (AM1) efficient solar cells.

Douglas, E. C.; Daiello, R. V.

1980-01-01

288

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

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

289

D0 Silicon Upgrade: Control Dewar Steady State Thermodynamic Operating Goals  

Microsoft Academic Search

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

Russ Rucincki

1995-01-01

290

Electroluminescent device based on silicon nanopillars  

NASA Astrophysics Data System (ADS)

Silicon nanopillars were fabricated by using deep UV lithography, highly anisotropic silicon reactive ion etching based on fluorine chemistry, and high-temperature thermal oxidation for further thinning. Pillars with a diameter below 10 nm and a height in the 0.4-0.6 ?m range were obtained while lying on a very smooth bottom silicon surface. An isolating transparent polymer was then used to fill in the etched area containing the pillars and, therefore, planarize and isolate the pillars. Oxygen plasma was used in order to remove the resistance from the top of the pillars. They were then contacted by a thin contact layer (gold or indium tin oxide), evaporated on the top of them. An Ohmic contact was also formed on the back side of the wafer. The obtained device showed rectifying behavior and forward voltages exceeding 10-12 V electroluminescence was observed, visible with the naked eye.

Nassiopoulos, A. G.; Grigoropoulos, S.; Papadimitriou, D.

1996-10-01

291

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

292

Factors controlling the silicon isotope distribution in waters and surface sediments of the Peruvian coastal upwelling  

NASA Astrophysics Data System (ADS)

We present the first systematic study of the silicon isotope composition in the water column (?30Si) and in diatoms (?30Sidiatom) from the underlying surface sediments in a coastal upwelling region. The surface waters upwelling on the shelf off Peru are mainly fed by southward flowing subsurface waters along the coast, which show a mean ?30Si of +1.5‰. The concentration of dissolved silicic acid (Si(OH)4) increases towards the south in these waters and with increasing water depth, suggesting lateral mixing with water masses from the south and intense remineralisation of particulate biogenic silica (bSiO2) in the water column and in the surface sediments. Surface waters in the realm of the most intense upwelling between 5°S and 15°S have only marginally elevated ?30Si values (?30Si = +1.7‰) with respect to the source Si isotope composition, whereas further north and south, where upwelling is less pronounced, surface waters are more strongly fractionated (?30Si up to +2.8‰) due to the stronger utilisation of the smaller amounts of available Si(OH)4. The degree of Si(OH)4 utilisation in the surface waters along the shelf estimated from the Si(OH)4 concentration data ranges from 51% to 93%. The ?30Sidiatom values of hand-picked diatoms in the underlying surface sediments vary from +0.6‰ to +2.0‰, which is within the range of the expected fractionation between surface waters and diatoms. The fractionation signal in the surface waters produced during formation of the diatoms is reflected by the ?30Sidiatom values in the underlying sediments, with the lowest ?30Sidiatom values in the main upwelling region. The silicon isotope compositions of bSiO2 (?30Si) from the same surface sediment samples are generally much lower than the ?30Sidiatom signatures indicating a significant contamination of the bSiO2 with biogenic siliceous material other than diatoms, such as sponge spicules. This shift towards lighter ?30Si values by up to -1.3‰ compared to ?30Sidiatom signatures for the same surface sediment samples potentially biases the interpretation of ?30Si paleorecords from sediments with low bSiO2 concentrations, and thus the reconstruction of past Si(OH)4 utilisation in surface waters.

Ehlert, Claudia; Grasse, Patricia; Mollier-Vogel, Elfi; Böschen, Tebke; Franz, Jasmin; de Souza, Gregory F.; Reynolds, Ben C.; Stramma, Lothar; Frank, Martin

2012-12-01

293

Modern Efficient Silicon-Rectifier-Type MultipleUnit Cars for Philadelphia Area Commuter Service  

Microsoft Academic Search

After 3 years of careful evaluation, a modern electric multiple-unit passenger car operating under an 11-kv 25-cycle catenary system has been placed in commuter service on two railroads in the Philadelphia area. Its high-strength stainless steel car body with plastic interior finish, modern lighting, and modulated air conditioning, combines maximum space utilization with maximum passenger comfort and appeal. High-capacity d-c

S. V. Smith

1964-01-01

294

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

E-print Network

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

Paris-Sud XI, Université de

295

A Theoretical Investigation on Rectifying Performance of a Single Motor Molecular Device  

NASA Astrophysics Data System (ADS)

We report ab initio calculations of the transport behavior of a phenyl substituted molecular motor. The calculated results show that the transport behavior of the device is sensitive to the rotation degree of the rotor part. When the rotor part is parallel with the stator part, a better rectifying performance can be found in the current-voltage curve. However, when the rotor part revolves to vertical with the stator part, the currents in the positive bias region decrease slightly. More importantly, the rectifying performance disappears. Thus this offers us a new method to modulate the rectifying behavior in molecular devices.

Lei, Hui; Tan, Xun-Qiong

2015-02-01

296

Novel silicone compatible cross-linkers for controlled functionalization of PDMS networks  

NASA Astrophysics Data System (ADS)

Polydimethylsiloxane (PDMS) elastomers are excellent materials for dielectric electroactive polymers (DEAPs) due to their high efficiency and fast response. PDMS suffers, however, from low dielectric permittivity and high voltages are therefore required when the material is used for DEAP actuators. In order to improve the dielectric properties of PDMS a novel system is developed where push-pull dipoles are grafted to a new silicone compatible cross-linker. The grafted cross-linkers are prepared by reaction of two different push-pull dipole alkynes as well as a fluorescent alkyne with the new azide-functional cross-linker by click chemistry. The dipole cross-linkers are used to prepare PDMS elastomers of various chains lengths providing different network densities. The functionalized cross-linkers are incorporated successfully into the networks and are well distributed as determined by the fluorescent functional cross-linker and fluorescence microscopy. The thermal, mechanical and electro-mechanical properties of PDMS elastomers of 0 wt% to 3.6 wt% of push-pull dipole cross-linker are investigated. An increase in the dielectric permittivity of 19 % at only 0.46 wt% of pure push-pull dipole is observed. Furthermore, the dielectric losses are found to be very low while the electrical breakdown strengths are high and adequate for DEAP applications.

Madsen, Frederikke B.; Egede Daugaard, Anders; Hvilsted, Søren; Skov, Anne Ladegaard

2013-04-01

297

An RF Energy Harvester System Using UHF Micropower CMOS Rectifier Based on a Diode Connected CMOS Transistor  

PubMed Central

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

Shokrani, Mohammad Reza; Hamidon, Mohd Nizar B.; Rokhani, Fakhrul Zaman; Shafie, Suhaidi Bin

2014-01-01

298

D0 Silicon Strip Detector Upgrade Project SVX Sequencer Controller Board  

SciTech Connect

The Sequencer Controller boards are 9U by 340mm circuit boards that will reside in slot 1 of each of eight Sequencer crates in the D0 detector platform. The primary purpose is to control the Sequencers during data acquisition based on trigger information from the D0 Trigger Framework. Functions and features are as follows: (1) Receives the Serial Command Link (SCL) from the D0 Trigger System and controls the operation of the Sequencers by forming a custom serial control link (NRZ/Clock) which is distributed individually to each Sequencer via the 11 Backplane; (2) Controllable delays adjust NRZ control link phasing to compensate for the various cable-length delays between the Sequencers and SVX chips, delay control is common for slots 2-11, and for slots 12-21 of the crate; (3) Each NRZ control link is phase controlled so that commands reach each Sequencer in a given half-crate simultaneously, i.e., the link is compensated for backplane propagation delays; (4) External communication via MIL-STD-1553; (5) Stand-alone operation via 1553 trigger commands in absence of an SCL link; (6) 1553-writeable register for triggering a laser, etc. followed by an acquisition cycle; (7) TTL front panel input to trigger an acquisition cycle, e.g. from a scintillator; (8) Synch Trig, Veto, Busy and Preamp Reset TTL outputs on front panel LEMOs; (9) On-board 53.104 MHz oscillator for stand-alone operation; (10) 1553 or SCL-triggerable Cal-inject cycle; (11) Front-panel inputs to accept NRZ/Clock link from the VRB Controller; (12) Front panel displays and LEDs show the board status at a glance; and (13) In-system programmable EPLDs are programmed via Altera's 'Byteblaster'.

Utes, M.; /Fermilab

2001-05-29

299

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

SciTech Connect

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

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

1995-12-31

300

Cocaine elicits action potential bursts in a central snail neuron: the role of delayed rectifying K+ current.  

PubMed

The effects of cocaine were studied in an identifiable RP4 neuron of the African snail, Achatina fulica Ferussac, using the two-electrode voltage-clamp method. The RP4 neuron generated spontaneous action potentials and bath application of cocaine (0.3-1 mM) reversibly elicited action potential bursts of the central RP4 neuron in a concentration-dependent manner. The action potential bursts were not blocked when neurons were immersed in high-Mg(2+)solution, Ca(2+)-free solution, nor after continuous perfusion with atropine, d-tubocurarine, propranolol, prazosin, haloperidol, or sulpiride. Similarly, the action potential bursts were not abolished by pretreatment with N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride, (9S,10S,12R)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-i][1,6]benzodiazocine-10-carboxylic acid hexyl ester or anisomycin. Injection of hyperpolarizing current at an intensity of greater than 2 nA effectively suppressed the cocaine-elicited action potential bursts and no postsynaptic potentials were observed under these conditions. These results suggest that the generation of action potential bursts elicited by cocaine was not due to (1) the synaptic effects of neurotransmitters, (2) the cholinergic, adrenergic or dopaminergic receptors of the excitable membrane, or (3) the cAMP second messengers and new protein synthesis of the RP4 neuron. Notably, the induction of action potential bursts was blocked by pretreatment with 1-[6-[((17beta)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione. Voltage-clamp studies conducted on the RP4 neuron revealed that cocaine at 0.3 mM decreased (1) the Ca(2+) current, (2) the delayed rectifying K(+) current, (3) the fast-inactivating K(+) current and (4) the Ca(2+)-activated K(+) current, but had no remarkable effects on the Na(+) current. Perfusion with Ca(2+)-free solution, which may abolish the Ca(2+) current and Ca(2+)-activated K(+) current, did not cause any bursts of action potentials in control RP4 neurons. Application of 4-aminopyridine, an inhibitor of fast-inactivating K(+) current, and paxilline, an inhibitor of Ca(2+)-activated K(+) current, failed to elicit action potential bursts, whereas tetraethylammonium chloride, a blocker of Ca(2+)-activated K(+) current and delayed rectifying K(+) current, and tacrine, an inhibitor of delayed rectifying K(+) current, successfully elicited action potential bursts. Further, while 1-[6-[((17beta)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione did not affect the delayed rectifying K(+) current of the RP4 neuron, 1-[6-[((17beta)-3-methoxyestra-1,3,5[10]-trien-17-yl)amino]hexyl]-1H-pyrrole-2,5-dione decreased the inhibitory effect of cocaine on the delayed rectifying K(+) current. It is concluded that cocaine elicits action potential bursts in the central snail RP4 neuron and that the effect is closely related to the inhibitory effects on the delayed rectifying K(+) current. PMID:16377093

Chen, Y-H; Lin, C-H; Lin, P-L; Tsai, M-C

2006-01-01

301

Atomic scale control and understanding of cubic silicon carbide surface reconstructions, nanostructures and nanochemistry  

NASA Astrophysics Data System (ADS)

The atomic scale ordering and properties of cubic silicon carbide (bgr-SiC) surfaces and nanostructures are investigated by atom-resolved room and high-temperature scanning tunnelling microscopy (STM) and spectroscopy (STS), synchrotron radiation-based valence band and core level photoelectron spectroscopy (VB-PES, CL-PES) and grazing incidence x-ray diffraction (GIXRD). In this paper, we review the latest results on the atomic scale understanding of (i) the structure of bgr-SiC(100) surface reconstructions, (ii) temperature-induced metallic surface phase transition, (iii) one dimensional Si(C) self-organized nanostructures having unprecedented characteristics, and on (iv) nanochemistry at SiC surfaces with hydrogen. The organization of these surface reconstructions as well as the 1D nanostructures' self-organization are primarily driven by surface stress. In this paper, we address such important issues as (i) the structure of the Si-rich 3 × 2, the Si-terminated c (4 × 2), the C-terminated c (2 × 2) reconstructions of the bgr-SiC(100) surface, (ii) the temperature-induced reversible {\\mathrm {c}}(4\\times 2) \\Leftrightarrow 2\\times 1 metallic phase transition, (iii) the formation of highly stable (up to 900 °C) Si atomic and vacancy lines, (iv) the temperature-induced sp to sp3 diamond like surface transformation, and (v) the first example of H-induced semiconductor surface metallization on the bgr-SiC (100) 3 × 2 surface. The results are discussed and compared to other experimental and theoretical investigations.

Soukiassian, Patrick G.; Enriquez, Hanna B.

2004-05-01

302

RECTIFIABILITY VIA A SQUARE FUNCTION AND PREISS' XAVIER TOLSA AND TATIANA TORO  

E-print Network

RECTIFIABILITY VIA A SQUARE FUNCTION AND PREISS' THEOREM XAVIER TOLSA AND TATIANA TORO Abstract. Phelps Professorship in Mathematics . 1 #12;2 XAVIER TOLSA AND TATIANA TORO exists and is positive for µ

Tolsa, Xavier

303

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

E-print Network

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

Li, Wei

304

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

E-print Network

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

Perreault, David J.

305

Perfomance Analysi of Rectifier in NH3-H2O Absorption Heat Pump  

NASA Astrophysics Data System (ADS)

In order to design a rectifier in NH3-H2O absorption heat pump, the heat and mass transfer model for packed tower-type rectifiers was presented in the previous paper and it was found that the model could predict over-all mass transfer coefficient within 30(%) difference to the experimental data. Though the approximate calculation to design rectifiers is increasing important, the method of this prediction need many reiteration along the vapor and solution flow, which might not be the simplified way to design packed tower-type rectifier Thus the approximate pr . edicting method was presented in this paper. In this way, over-all mass transfer Coefficient was easily deriveded using the rectification characteristic that was determined by the dimension and geometry of rectification packing. The calculation results showed good agreement with the experimental data, regardless of kinds of rectification packing.

Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige

306

Design and test of a 2.25-MW transformer rectifier assembly  

NASA Technical Reports Server (NTRS)

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

Cormier, R.; Daeges, J.

1989-01-01

307

Design considerations and experimental analysis of high-voltage SiC Schottky barrier rectifiers  

Microsoft Academic Search

Practical design of high-voltage SiC Schottky rectifiers requires an understanding of the device physics that affect the key performance parameters. Forward characteristics of SiC Schottky rectifiers follow thermionic emission theory and are relatively well understood. However, the reverse characteristics are not well understood and have not been experimentally investigated in-depth. In this paper we report the analysis and experimental results

Kipp Jay Schoen; Jerry M. Woodall; James A. Cooper; Michael R. Melloch

1998-01-01

308

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

E-print Network

in an optimal passive RF complex load. The MMICs are designed in a 0.15fLm gate length TriQuint GaN on SiHigh-Efficiency X-Band MMIC GaN Power Amplifiers Operating as Rectifiers Michael Litchfield, Scott presents a performance evaluation of GaN X-Band power amplifiers operating as self-synchronous rectifiers

Popovic, Zoya

309

Dielectrically isolated lateral high voltage PiN rectifiers for power ICs  

Microsoft Academic Search

Lateral DI and JI P-i-N rectifiers with breakdown voltages up to 600 V have been fabricated by using the RESURF principle. The reverse recovery times for the DI rectifiers were measured to be much smaller than those in JI devices, which two-dimensional numerical simulation shows to be due to elimination of injection into the substrate. This injection is also responsible

S. Sridhar; Y. S. Huang; B. J. Baliga

1992-01-01

310

A new active interphase reactor for 12-pulse rectifiers provides clean power utility interface  

Microsoft Academic Search

In this paper, a new active interphase reactor for twelve-pulse diode rectifiers is proposed. The proposed system draws near sinusoidal currents from the electric utility. In this scheme, a low kVA (0.03 per unit) active current source injects a triangular current into an interphase reactor of a twelve-pulse diode rectifier. The modification results in near sinusoidal input current with less

Sewan Choi; Prasad N Enjeti; Honghee Lee; Ira J Pitel

1995-01-01

311

Periodically poled silicon  

NASA Astrophysics Data System (ADS)

Bulk centrosymmetric silicon lacks second-order optical nonlinearity ?(2) - a foundational component of nonlinear optics. Here, we propose a new class of photonic device which enables ?(2) as well as quasi-phase matching based on periodic stress fields in silicon - periodically-poled silicon (PePSi). This concept adds the periodic poling capability to silicon photonics, and allows the excellent crystal quality and advanced manufacturing capabilities of silicon to be harnessed for devices based on ?(2)) effects. The concept can also be simply achieved by having periodic arrangement of stressed thin films along a silicon waveguide. As an example of the utility, we present simulations showing that mid-wave infrared radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion efficiency of 50% based on ?(2) values measurements for strained silicon reported in the literature [Jacobson et al. Nature 441, 199 (2006)]. The use of PePSi for frequency conversion can also be extended to terahertz generation. With integrated piezoelectric material, dynamically control of ?(2)nonlinearity in PePSi waveguide may also be achieved. The successful realization of PePSi based devices depends on the strength of the stress induced ?(2) in silicon. Presently, there exists a significant discrepancy in the literature between the theoretical and experimentally measured values. We present a simple theoretical model that produces result consistent with prior theoretical works and use this model to identify possible reasons for this discrepancy.

Hon, Nick K.; Tsia, Kevin K.; Solli, Daniel R.; Khurgin, Jacob B.; Jalali, Bahram

2010-02-01

312

Inhibition of the delayed rectifier K current in guinea-pig cardiomyocytes by thiamine tetrahydrofurfuryl disulfide.  

PubMed

We examined effect of thiamine tetrahydrofurfuryl disulfide on electrophysiological characteristics of single atrial myocytes, obtained by digestion of guinea-pig heart, using collagenase. Membrane potential and ion channel current in the atrial myocytes were recorded by the patch clamp method. Thiamine tetrahydrofurfuryl disulfide prolonged action potentials at cycle lengths from 250 to 10,000 ms. The degree of thiamine tetrahydrofurfuryl disulfide-induced prolongation was similar among these cycle lengths. Thiamine tetrahydrofurfuryl disulfide inhibited the delayed rectifier K+ current, without affecting Ca2+ current and inward-rectifier K+ current. Thiamine tetrahydrofurfuryl disulfide blocked the delayed rectifier K+ current in voltage- and time-independent manner, indicating that thiamine tetrahydrofurfuryl disulfide blocked both subtypes of the delayed rectifier K+ current (rapid and slow components). Thiamine, the parent molecule of thiamine tetrahydrofurfuryl disulfide, blocked the delayed rectifier K+ current only when thiamine was applied intracellularly. Thiamine tetrahydrofurfuryl disulfide may be converted to thiamine in the cytoplasm, and then may block the the delayed rectifier K+ channel from the intracellular side. Although thiamine tetrahydrofurfuryl disulfide (or thiamine) has some of the properties of class III antiarrhythmics agents, thiamine tetrahydrofurfuryl disulfide did not exhibit reverse use-dependent prolongation of action potential. PMID:9650807

Tohse, N; Houzen, H; Kanno, M

1998-05-01

313

New Analysis and Design of a RF Rectifier for RFID and Implantable Devices  

PubMed Central

New design and optimization of charge pump rectifiers using diode-connected MOS transistors is presented in this paper. An analysis of the output voltage and Power Conversion Efficiency (PCE) is given to guide and evaluate the new design. A novel diode-connected MOS transistor for UHF rectifiers is presented and optimized, and a high efficiency N-stage charge pump rectifier based on this new diode-connected MOS transistor is designed and fabricated in a SMIC 0.18-?m 2P3M CMOS embedded EEPROM process. The new diode achieves 315 mV turn-on voltage and 415 nA reverse saturation leakage current. Compared with the traditional rectifier, the one based on the proposed diode-connected MOS has higher PCE, higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the power ranging from ?15 dBm to ?4 dBm, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.5 V, and its ripple coefficients are less than 1%. Therefore, the rectifier is especially suitableto passive UHF RFID tag IC and implantable devices. PMID:22163968

Liu, Dong-Sheng; Li, Feng-Bo; Zou, Xue-Cheng; Liu, Yao; Hui, Xue-Mei; Tao, Xiong-Fei

2011-01-01

314

Performance Analysis of Rectifier in NH3-H2O Absorprtion Heat Pump  

NASA Astrophysics Data System (ADS)

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.

Tsujimori, Atsushi; Ozaki, Eiichi; Nakao, Kazushige

315

D0 Silicon Upgrade: Cryolab Control Valve Modification Information for D0-EVMF-H  

SciTech Connect

This engineering note documents some information regarding the solenoid magnet flow valve, EVMF. See also EN-437 'Control Dewar valve sizing' also for further information on this valve. This note documents the modification done to the valve to change it to a Cv = 0.32.

Rucincki, Russ; /Fermilab

1995-10-26

316

Controlling Articulated Robots in Task-Space with Spiking Silicon Neurons  

E-print Network

has achieved real- time manipulation for an articulated robot with three or more degrees-of-freedom. I controlled a three degree-of-freedom robot's motor torques in real-time and performed reaches to arbitrary], or to correct linear torque errors for a two degree-of-freedom robot [7]. Previous attempts to use spiking

Boahen, Kwabena

317

Post-transcriptional regulation of GORK channels by superoxide anion contributes to increases in outward-rectifying K? currents.  

PubMed

· Ion fluxes are ubiquitous processes in the plant and animal kingdoms, controlled by fine-tuned regulations of ion channel activity. Yet the mechanism that cells employ to achieve the modification of ion homeostasis at the molecular level still remains unclear. This is especially true when it comes to the mechanisms that lead to cell death. · In this study, Arabidopsis thaliana cells were exposed to ozone (O?). Ion flux variations were analyzed by electrophysiological measurements and their transcriptional regulation by RT-PCR. Reactive oxygen species (ROS) generation was quantified by luminescence techniques and caspase-like activities were investigated by laser confocal microscopy. · We highlighted the delayed activation of K(+) outward-rectifying currents after an O? -induced oxidative stress leading to programmed cell death (PCD). Caspase-like activities are detected under O? exposure and could be decreased by K(+) channel blocker. Molecular experiments revealed that the sustained activation of K(+) outward current could be the result of an unexpected O? ·? post-transcriptional regulation of the guard cell outward-rectifying K(+) (GORK) channels. · This consists of a likely new mode of regulating the processing of the GORK mRNA, in a ROS-dependent manner, to allow sustained K(+) effluxes during PCD. These data provide new mechanistic insights into K(+) channel regulation during an oxidative stress response. PMID:23517047

Tran, Daniel; El-Maarouf-Bouteau, Hayat; Rossi, Marika; Biligui, Bernadette; Briand, Joël; Kawano, Tomonori; Mancuso, Stefano; Bouteau, François

2013-06-01

318

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

319

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

320

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

PubMed

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

Tandara, Andrea A; Mustoe, Thomas A

2008-10-01

321

Copper-capped carbon nanocones on silicon: plasma-enabled growth control.  

PubMed

Controlled self-organized growth of vertically aligned carbon nanocone arrays in a radio frequency inductively coupled plasma-based process is studied. The experiments have demonstrated that the gaps between the nanocones, density of the nanocone array, and the shape of the nanocones can be effectively controlled by the process parameters such as gas composition (hydrogen content) and electrical bias applied to the substrate. Optical measurements have demonstrated lower reflectance of the nanocone array as compared with a bare Si wafer, thus evidencing their potential for the use in optical devices. The nanocone formation mechanism is explained in terms of redistribution of surface and volumetric fluxes of plasma-generated species in a developing nanocone array and passivation of carbon in narrow gaps where the access of plasma ions is hindered. Extensive numerical simulations were used to support the proposed growth mechanism. PMID:23062476

Kumar, Shailesh; Levchenko, Igor; Farrant, David; Keidar, Michael; Kersten, Holger; Ostrikov, Kostya Ken

2012-11-01

322

Formation mechanism and control of MgO·Al2O3 inclusions in non-oriented silicon steel  

NASA Astrophysics Data System (ADS)

On the basis of the practical production of non-oriented silicon steel, the formation of MgO·Al2O3 inclusions was analyzed in the process of "basic oxygen furnace (BOF) ? RH ? compact strip production (CSP)". The thermodynamic and kinetic conditions of the formation of MgO·Al2O3 inclusions were discussed, and the behavior of slag entrapment in molten steel during RH refining was simulated by computational fluid dynamics (CFD) software. The results showed that the MgO/Al2O3 mass ratio was in the range from 0.005 to 0.017 and that MgO·Al2O3 inclusions were not observed before the RH refining process. In contrast, the MgO/Al2O3 mass ratio was in the range from 0.30 to 0.50, and the percentage of MgO·Al2O3 spinel inclusions reached 58.4% of the total inclusions after the RH refining process. The compositions of the slag were similar to those of the inclusions; furthermore, the critical velocity of slag entrapment was calculated to be 0.45 m·s-1 at an argon flow rate of 698 L·min-1, as simulated using CFD software. When the test steel was in equilibrium with the slag, [Mg] was 0.00024wt%-0.00028wt% and [Al]s was 0.31wt%-0.37wt%; these concentrations were theoretically calculated to fall within the MgO·Al2O3 formation zone, thereby leading to the formation of MgO·Al2O3 inclusions in the steel. Thus, the formation of MgO·Al2O3 inclusions would be inhibited by reducing the quantity of slag entrapment, controlling the roughing slag during casting, and controlling the composition of the slag and the MgO content in the ladle refractory.

Sun, Yan-hui; Zeng, Ya-nan; Xu, Rui; Cai, Kai-ke

2014-11-01

323

BOREAS TE-18, 30-m, Radiometrically Rectified Landsat TM Imagery  

NASA Technical Reports Server (NTRS)

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 21-Jun-1995. the 23 rectified images cover the period of 07-Jul-1985 to 18 Sep-1994 in the SSA and from 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. (199 1). The original Landsat TM data were received from CCRS for use in the BOREAS project. The data are stored in binary image-format files. Due to the nature of the radiometric rectification process and copyright issues, these full-resolution images may not be publicly distributed. However, a spatially degraded 60-m resolution version of the images is available on the BOREAS CD-ROM series. See Sections 15 and 16 for information about how to possibly acquire the full resolution data. Information about the full-resolution images is provided in an inventory listing on the CD-ROMs. 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).

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

2000-01-01

324

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

NASA Technical Reports Server (NTRS)

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).

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

2000-01-01

325

Delayed rectifier K+ current in rabbit atrial myocytes.  

PubMed

The role of delayed rectifier K+ current(s) (IK) in rabbit left atrium was examined by applying the whole cell voltage-clamp technique to isolated single myocytes. Right-triangular waveforms, which mimic the shape of atrial action potentials (APs), and selective blockers were used to compare the contribution of IK with other K+ currents to repolarization of the APs. IK measured at 34 degrees C in atrial myocytes was very small; the maximum peak amplitude of the tail current (IK,tail) at -40 mV was approximately 50 pA. The IK,tail was almost abolished in most cells (approximately 80%) by the application of 1 microM E-4031, a class III antiarrhythmic drug. The E-4031-sensitive current recorded with the triangular command wave-form showed strong inward rectification and had a maximum amplitude of approximately 30 pA at -40 mV. Total outward current elicited by triangular command pulses depended strongly on stimulation frequency. The main frequency-dependent component was a Ca(2+)-independent transient K+ current (I(t)). I(t) elicited by triangular pulses at 1 Hz was substantially reduced by 4-aminopyridine (4-AP) at potentials positive to 0 mV but was not changed significantly by 1 microM E-4031; 100 microM E-4031 reduced I(t) by approximately 30%. The shape of the APs which were recorded from a single rabbit atrial cell strongly depended on the pulse frequency. Application of 1 microM E-4031 increased action potential duration (APD) in > 50% of cells examined but had little effect on the resting membrane potential (RMP). Application of 0.1 mM BaCl2 also lengthened APD and reduced RMP by approximately 20 mV.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7653616

Muraki, K; Imaizumi, Y; Watanabe, M; Habuchi, Y; Giles, W R

1995-08-01

326

An inwardly rectifying K+ channel is required for patterning  

PubMed Central

Mutations that disrupt function of the human inwardly rectifying potassium channel KIR2.1 are associated with the craniofacial and digital defects of Andersen-Tawil Syndrome, but the contribution of Kir channels to development is undefined. Deletion of mouse Kir2.1 also causes cleft palate and digital defects. These defects are strikingly similar to phenotypes that result from disrupted TGF?/BMP signaling. We use Drosophila melanogaster to show that a Kir2.1 homolog, Irk2, affects development by disrupting BMP signaling. Phenotypes of irk2 deficient lines, a mutant irk2 allele, irk2 siRNA and expression of a dominant-negative Irk2 subunit (Irk2DN) all demonstrate that Irk2 function is necessary for development of the adult wing. Compromised Irk2 function causes wing-patterning defects similar to those found when signaling through a Drosophila BMP homolog, Decapentaplegic (Dpp), is disrupted. To determine whether Irk2 plays a role in the Dpp pathway, we generated flies in which both Irk2 and Dpp functions are reduced. Irk2DN phenotypes are enhanced by decreased Dpp signaling. In wild-type flies, Dpp signaling can be detected in stripes along the anterior/posterior boundary of the larval imaginal wing disc. Reducing function of Irk2 with siRNA, an irk2 deletion, or expression of Irk2DN reduces the Dpp signal in the wing disc. As Irk channels contribute to Dpp signaling in flies, a similar role for Kir2.1 in BMP signaling may explain the morphological defects of Andersen-Tawil Syndrome and the Kir2.1 knockout mouse. PMID:22949619

Dahal, Giri Raj; Rawson, Joel; Gassaway, Brandon; Kwok, Benjamin; Tong, Ying; Ptá?ek, Louis J.; Bates, Emily

2012-01-01

327

Polycrystalline silicon availability for photovoltaic and semiconductor industries  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

328

Characteristics of degenerately doped silicon for spectral control in thermophotovoltaic systems  

SciTech Connect

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%.

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

329

Automotive Power Generation and Control  

E-print Network

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

Caliskan, Vahe

330

Controllable shrinking and shaping of silicon nitride nanopores under electron irradiation  

SciTech Connect

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

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

2007-04-16

331

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

SciTech Connect

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

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

1991-11-01

332

Gate Tunable Graphene-Silicon Ohmic/Schottky Contact  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

333

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

PubMed

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

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

2015-02-01

334

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

SciTech Connect

Inward-rectifier potassium (K{sup +}) channels conduct K{sup +} 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{sup +}), strontium (Sr{sup 2+}), and europium (Eu{sup 3+}) 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{sup +} channel family.

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

2010-03-29

335

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

Microsoft Academic Search

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

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

2007-01-01

336

A general approach toward shape-controlled synthesis of silicon nanowires.  

PubMed

Controlling the morphology, electronic properties, and growth direction of nanowires (NWs) is an important aspect regarding their integration into devices on technologically relevant scales. Using the vapor-solid-solid (VSS) approach, with Ni as a catalyst and octachlorotrisilane (Si(3)Cl(8), OCTS) as a precursor, we achieved epitaxial growth of rectangular-shaped Si-NWs, which may have important implications for electronic mobility and light scattering in NW devices. The process parameters were adjusted to form cubic ?-NiSi(2) particles which further act as the shaping element leading to prismatic Si-NWs. Along with the uncommon shape, also different crystallographic growth directions, namely, [100] and [110], were observed on the very same sample. The growth orientations were determined by analysis of the NWs' azimuths on the Si (111) substrates as well as by detailed transmission electron microscopy (TEM) and selected area electron diffraction (SAED) investigations. PMID:23214964

Molnar, W; Lugstein, A; Pongratz, P; Seyring, M; Rettenmayr, M; Borschel, C; Ronning, C; Auner, N; Bauch, C; Bertagnolli, E

2013-01-01

337

Position-controlled uniform GaAs nanowires on silicon using nanoimprint lithography.  

PubMed

We report on the epitaxial growth of large-area position-controlled self-catalyzed GaAs nanowires (NWs) directly on Si by molecular beam epitaxy (MBE). Nanohole patterns are defined in a SiO2 mask on 2 in. Si wafers using nanoimprint lithography (NIL) for the growth of positioned GaAs NWs. To optimize the yield of vertical NWs the MBE growth parameter space is tuned, including Ga predeposition time, Ga and As fluxes, growth temperature, and annealing treatment prior to NW growth. In addition, a non-negligible radial growth is observed with increasing growth time and is found to be independent of the As species (i.e., As2 or As4) and the growth temperatures studied. Cross-sectional transmission electron microscopy analysis of the GaAs NW/Si substrate heterointerface reveals an epitaxial growth where NW base fills the oxide hole opening and eventually extends over the oxide mask. These findings have important implications for NW-based device designs with axial and radial p-n junctions. Finally, NIL positioned GaAs/AlGaAs core-shell heterostructured NWs are grown on Si to study the optical properties of the NWs. Room-temperature photoluminescence spectroscopy of ensembles of as-grown core-shell NWs reveals uniform and high optical quality, as required for the subsequent device applications. The combination of NIL and MBE thereby demonstrates the successful heterogeneous integration of highly uniform GaAs NWs on Si, important for fabricating high throughput, large-area position-controlled NW arrays for various optoelectronic device applications. PMID:24467394

Munshi, A M; Dheeraj, D L; Fauske, V T; Kim, D C; Huh, J; Reinertsen, J F; Ahtapodov, L; Lee, K D; Heidari, B; van Helvoort, A T J; Fimland, B O; Weman, H

2014-02-12

338

Silicon control of strontium and cesium partitioning in hydroxide-weathered sediments  

NASA Astrophysics Data System (ADS)

Cation partitioning and speciation in an aqueous soil suspension may depend 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 Sr 2+ and Cs + introduced to the subsurface by caustic high level radioactive waste (HLRW). Three glacio-fluvial and lacustrine sediments from the Hanford Site (WA, USA) were subjected to hyperalkaline (pH > 13), Na-Al-NO 3-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 Sr 2+ 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 Sr 2+; 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 Sr 2+-containing cancrinite and sodalite was observed after 183 d by SEM and synchrotron ?-XRF and ?-XRD. EXAFS data for qSr ? 40 mmol kg -1 showed incorporation of Sr 2+ into both feldspathoid and SrCO 3(s) coordination environments after one year. Adsorption was predominant at early times and low sorbate amount, whereas precipitation, 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 (Ca 2+ versus K +) composition. Results of this study indicate that co-precipitation and ion exchange in neoformed aluminosilicates may be an important mechanism controlling Sr 2+ and Cs + mobility in siliceous sediments impacted by hyperalkaline HLRW.

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

2008-04-01

339

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

NASA Technical Reports Server (NTRS)

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

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

1978-01-01

340

D0 Silicon Upgrade: Control Dewar Venturi Calibration Explanation for Toshiba  

SciTech Connect

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

Kuwazaki, Andrew; /Fermilab

1997-01-24

341

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

NASA Astrophysics Data System (ADS)

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.

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

2009-11-01

342

Inward rectifier K+-channel kinetics from analysis of the complex conductance of Aplysia neuronal membrane.  

PubMed Central

Conduction in inward rectifier, K+-channels in Aplysia neuron and Ba++ blockade of these channels were studied by rapid measurement of the membrane complex admittance in the frequency range 0.05 to 200 Hz during voltage clamps to membrane potentials in the range -90 to -40 mV. Complex ionic conductances of K+ and Cl- rectifiers were extracted from complex admittances of other membrane conduction processes and capacitance by vector subtraction of the membrane complex admittance during suppressed inward K+ current (near zero-mean current and in zero [K+]0) from complex admittances determined at other [K+]0 and membrane potentials. The contribution of the K+ rectifier to the admittance is distinguishable in the frequency domain above 1 Hz from the contribution of the Cl- rectifier, which is only apparent at frequencies less than 0.1 Hz. The voltage dependence (-90 to -40 mV) of the chord conductance (0.2 to 0.05 microS) and the relaxation time (4-8 ms) of K+ rectifier channels at [K+]0 = 40 mM were determined by curve fits of admittance data by a membrane admittance model based on the linearized Hodgkin-Huxley equations. The conductance of inward rectifier, K+ channels at a membrane potential of -80 mV had a square-root dependence on external K+ concentration, and the relaxation time increased from 2 to 7.5 ms for [K+]0 = 20 and 100 mM, respectively. The complex conductance of the inward K+ rectifier, affected by Ba++, was obtained by complex vector subtraction of the membrane admittance during blockage of inward rectifier, K+ channels (at -35 mV and [Ba++]0 = 5 mM) from admittances determined at -80 mV and at other Ba++ concentrations. The relaxation time of the blockade process decreased with increases in Ba++ concentration. An open-closed channel state model produces the inductive-like kinetic behavior in the complex conductance of inward rectifier, K+ channels and the addition of a blocked channel state accounts for the capacitive-like kinetic behavior of the Ba++ blockade process. PMID:2455551

Hayashi, H; Fishman, H M

1988-01-01

343

Composition Comprising Silicon Carbide  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

344

Serotonin Increases an Anomalously Rectifying K+ Current in the Aplysia Neuron R15  

NASA Astrophysics Data System (ADS)

Previous work has shown that serotonin causes an increase in K+ conductance in the identified Aplysia neuron R15. This response is mediated by cAMP-dependent protein phosphorylation. The results presented here show that the K+ channel modulated by serotonin is an anomalous or inward rectifier (designated IR) that is present in R15 together with the three other distinct K+ channels previously described for this cell. Several lines of evidence indicate that this inward rectifier is partially activated in the resting cell and is further activated by serotonin. Voltage clamp analysis of resting and serotonin-evoked membrane currents at various external K+ concentrations shows that both currents have reversal potentials close to the potassium equilibrium potential, exhibit similar dependences in magnitude on external K+ concentration, and display marked anomalous rectification. The effects of particular monovalent and divalent cations are also similar on the resting and serotonin-evoked currents. Rb+, Cs+, and Ba2+ block both currents while Tl+ can substitute for K+ as a charge carrier and channel activator in both. These properties are characteristic of anomalous rectifiers in other systems. Furthermore, measurement of the voltage dependence of inactivation for the fast transient K+ current shows that this current cannot account for the anomalously rectifying K+ conductance in R15. The inward rectifier is therefore a separate current mediated by its own channels, the activity of which can be modulated by serotonin.

Benson, Jack A.; Levitan, Irawin B.

1983-06-01

345

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

NASA Astrophysics Data System (ADS)

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.

Lee, Ki-Hong

346

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

PubMed

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

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

2013-02-25

347

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

PubMed Central

The rectifying properties of ?,?-dithiol terminated oligo(phenylene ethynylene) molecules sandwiched between heterometallic electrodes, including the molecular length and side group effects, are theoretically investigated using the fully self-consistent nonequilibrium Green's function method combined with density functional theory. The results show nonlinear variation with changes in molecule length: when the molecule becomes longer, the current decreases at first and then increases while the rectification shifts in the opposite direction. This stems from the change in molecular eigenstates and the coupling between the molecule and electrodes caused by different molecular lengths. The rectifying behavior of heterometallic molecular junctions can be attributed to the asymmetric molecule-electrode contacts, which lead to asymmetric electronic tunneling spectra, molecular eigenvalues, molecular orbitals, and potential drop at reversed equivalent bias voltages. Our results provide a fundamental understanding of the rectification of heterometallic molecular junction, and a prediction of rectifiers with different rectification properties from those in the experiment, using electrodes with reduced sizes. PMID:25220880

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

2014-01-01

348

Formation of periodic structures on silicon by laser beam interference ablation technique for light control in solar cells  

NASA Astrophysics Data System (ADS)

Silicon remains as the main material used in solar cell production, because of its low cost, abundance in nature and well-established technologies. However, its surface reflects considerable part of light due to its high refraction index. Light harvesting pays an important role for further progress to high-efficient solar cells. Texturing of the substrate surface is an efficient method to enhance the light absorption leading to the higher solar-to-electricity conversion efficiency in crystalline silicon solar cells. We present the novel method for silicon surface texturing using the direct laser beam interference ablation in addition with selective chemical etching. This technique enables production of high aspect ratio structures on a large surface area with just a single laser exposure. Characterization of the laser textured surfaces was performed using SEM. Theoretical simulation of light interaction with such structures was conducted in parallel and was used to adjust the laser process for more efficient light harvesting.

Voisiat, B.; Indriši?nas, S.; Suzanovi?ien?, R.; Šimkien?, I.; Ra?iukaitis, G.

2014-10-01

349

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

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

350

Direct Production of Silicones From Sand  

SciTech Connect

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

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

2001-09-30

351

Silicon-Web-Growing Machine  

NASA Technical Reports Server (NTRS)

Silicon replenished automatically as web is withdrawn. Semiautomatic silicon-web-growing machine set down in detailed engineering drawings. Melt level sensed with He/Ne laser beam and melt-level error signal used to control motor-driven pellet feeder, speeding up when level is low. System reduces demand upon operator's time.

Duncan, C.

1985-01-01

352

Development of an In-Line Minority-Carrier Lifetime Monitoring Tool for Process Control during Fabrication of Crystalline Silicon Solar Cells: Annual Subcontract Report, June 2003 (Revised)  

SciTech Connect

Under the PV Manufacturing R&D subcontract''Development of an In-Line, Minority-Carrier Lifetime Monitoring Tool for Process Control during Fabrication of Crystalline Silicon Solar Cells'', Sinton Consulting developed prototypes for several new instruments for use in the manufacture of silicon solar cells. These instruments are based on two families of R&D instruments that were previously available, an illumination vs. open-circuit-voltage technique and the quasi-steady state RF photoconductance technique for measuring minority-carrier lifetime. Compared to the previous instruments, the new prototypes are about 20 times faster per measurement, and have automated data analysis that does not require user intervention even when confronted by challenging cases. For example, un-passivated multi-crystalline wafers with large variations in lifetime and trapping behavior can be measured sequentially without error. Five instruments have been prototyped in this project to date, including a block tester for evaluating cast or HEM silicon blocks, a CZ ingot tester, an FZ boule tester for use with long-lifetime silicon, and an in-line sample head for measuring wafers. The CZ ingot tester and the FZ boule tester are already being used within industry and there is interest in the other prototypes. For each instrument, substantial R&D work was required in developing the device physics and analysis as well as for the hardware. This work has been documented in a series of application notes and conference publications, and will result in significant improvements for both the R&D and the industrial types of instruments.

Sinton, R. A.

2004-04-01

353

Recovery Act: High-Efficiency, Wideband Three-Phase Rectifiers and Adaptive Rectifier Management for Telecomm Central Office and Large Data Center Applications  

SciTech Connect

Lineage Power and Verizon teamed up to address a DOE funding opportunity focused on improving the power conversion chain in telecommunications facilities and data centers. The project had three significant elements: the design and development of high efficiency and high power three-phase rectifiers by Lineage Power, design and development of software to optimize overall plant energy efficiency by Lineage Power, and a field trial in active Verizon telecommunications facilities where energy consumption was measured before and after efficiency upgrades.

Mark A. Johnson

2012-06-29

354

Microrectenna: A Terahertz Antenna and Rectifier on a Chip  

NASA Technical Reports Server (NTRS)

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.

Siegel, Peter

2007-01-01

355

GORK, a delayed outward rectifier expressed in guard cells of Arabidopsis thaliana, is a K +-selective, K +-sensing ion channel  

Microsoft Academic Search

Here we report on the molecular identification, guard cell expression and functional characterization of AtGORK, an Arabidopsis thalianaguard cell outward rectifying K+ channel. GORK represents a new member of the plant Shaker K+ channel superfamily. When heterologously expressed in Xenopus oocytes the gene product of GORK mediated depolarization-activated K+ currents. In agreement with the delayed outward rectifier in intact guard

Peter Ache; Dirk Becker; Natalya Ivashikina; Petra Dietrich; M. Rob G Roelfsema; Rainer Hedrich

2000-01-01

356

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

E-print Network

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

Delacourt, Christophe

357

Somatostatin increases an inwardly rectifying potassium conductance in guinea-pig submucous plexus neurones.  

PubMed Central

1. Intracellular recordings were made from neurones in the submucous plexus of the guinea-pig caecum and ileum. 2. Somatostatin hyperpolarized more than 90% of the neurones. The lowest effective concentration was 300 pM and the maximum hyperpolarization (about 30-35 mV) was caused by 30 nM. Under voltage clamp at -60 mV, somatostatin caused outward currents which reached a maximum of 350-700 pA. 3. The hyperpolarization or outward current reversed polarity at a membrane potential (about -90 mV in control solutions) which changed according to the logarithm of the external potassium concentration. 4. The somatostatin current showed inward rectification; when the inward rectification of the resting membrane was prevented by extracellular caesium or rubidium, the inward rectification of the somatostatin current also disappeared. 5. A potassium conductance with the same properties was increased by alpha 2-adrenoceptor agonists and by delta-opioid receptor agonists; however, the effects of somatostatin were unaffected by antagonists at alpha 2- or delta-receptors. The somatostatin analogue, cyclo-aminoheptanoyl-Phe-D-Trp-Lys-(benzyl)Thr, also did not antagonize the actions of somatostatin. 6. The hyperpolarization (or outward current) was unaffected by forskolin, cholera toxin, sodium fluoride, phorbol esters or intracellular application of adenosine 5'-O-(3-thiotriphosphate) (ATP-gamma-S). However, when the recording electrode contained guanosine 5'-O-(3-thiotriphosphate) (GTP-gamma-S) the hyperpolarizations reversed only partially when somatostatin application was discontinued, and repeated applications caused the membrane potential to approach and remain close to the potassium equilibrium potential. 7. It is concluded that somatostatin increases the conductance of a set of inwardly rectifying potassium channels in submucous plexus neurones. The coupling between somatostatin receptor and ion channel involves a guanosine 5'-triphosphate-binding protein, but is not likely to result from changes in intracellular levels of cyclic adenosine 3',5'-monophosphate. PMID:2450994

Mihara, S; North, R A; Surprenant, A

1987-01-01

358

The silicon Schottky diode on flexible substrates by transfer method  

NASA Astrophysics Data System (ADS)

A flexible silicon barrier diode was fabricated by the transfer printing method. Micro-line patterned p-type single crystalline silicon membranes were created from a silicon on insulator wafer. The dark current of our device was very low, about 1 pA for reverse bias voltages up to 5 V, and showed rectifying behavior with an ideality factor of 1.05. The photo-response and the responsivity was 32 and 0.3 A/W, respectively, for light intensity of 1.2 mW/cm2. Also, the current of the photodetector changed under compressive stress or tensile stress. Our device is functional as the piezotronic sensor as well as the photodetector.

Oh, Tae-Yeon; Woo Jeong, Shin; Chang, Seongpil; Choi, Kookhyun; Jun Ha, Hyun; Kwon Ju, Byeong

2013-01-01

359

Unitary delayed rectifier channels of rat hippocampal neurons: properties of block by external tetraethylammonium ions  

Microsoft Academic Search

Patch-clamp recording was used to characterise a delayed rectifier potassium channel and the effects of external tetraethylammonium (TEA) in neurons isolated from the CA1 region of cultured neonatal rat hippocampus. A preliminary kinetic analysis is presented. Very low concentrations of TEA included in the patch pipette solution had two effects on unitary currents: first unitary currents were reduced in amplitude,

P. Linsdell; P. R. Stanfield

1993-01-01

360

Coupled Ion Movement Underlies Rectification in an Inward-Rectifier K+ Channel  

Microsoft Academic Search

We studied block of the internal pore of the ROMK1 inward-rectifier K 1 channel by Mg 2 1 and five quaternary ammoniums (tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammo- nium, and tetrapentylammonium). The apparent affinity of these blockers varied as a function of membrane volt- age. As a consequence, the channel conducted K 1 current more efficiently in the inward than the outward

Maria Spassova; Zhe Lu

1998-01-01

361

Self-Rectifying Effect in Resistive Switching Memory Using Amorphous InGaZnO  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

362

PHASE-RECTIFIED SIGNAL AVERAGING FOR THE QUANTIFICATION OF THE INFLUENCE OF PRENATAL ANXIETY  

E-print Network

PHASE-RECTIFIED SIGNAL AVERAGING FOR THE QUANTIFICATION OF THE INFLUENCE OF PRENATAL ANXIETY rate variabil- ity, Prenatal anxiety, Autonomic nervous system Abstract: The autonomic nervous system. In this way, the effect of stress and anxiety during pregnancy on the ANS of the baby is analyzed. First

363

Rectifying Electrical Synapses Can Affect the Influence of Synaptic Modulation on Output Pattern Robustness  

PubMed Central

Rectifying electrical synapses are commonplace, but surprisingly little is known about how rectification alters the dynamics of neuronal networks. In this study, we use computational models to investigate how rectifying electrical synapses change the behavior of a small neuronal network that exhibits complex rhythmic output patterns. We begin with an electrically coupled circuit of three oscillatory neurons with different starting frequencies, and subsequently add two additional neurons and inhibitory chemical synapses. The five-cell model represents a pattern-generating neuronal network with two simultaneous rhythms competing for the recruitment of a hub neuron. We compare four different configurations of rectifying synapse placement and polarity, and we investigate how rectification changes the functional output of this network. Rectification can have a striking effect on the network's sensitivity to alterations of the strengths of the chemical synapses in the network. For some configurations, the rectification makes the circuit dynamics remarkably robust against changes in synaptic strength compared with the nonrectifying case. Based on our findings, we predict that modulation of rectifying electrical synapses could have functional consequences for the neuronal circuits that express them. PMID:23926276

Gutierrez, Gabrielle J.

2013-01-01

364

A novel approach to gearbox condition monitoring by using drive rectifier input currents  

Microsoft Academic Search

Gearboxes are widely used and subjected to progressive deterioration which makes box condition monitoring a relevant topic in the servodrive industry. This paper proposes a novel scheme for performing integral condition monitoring in a drive containing a gearbox. The proposed scheme is based on a modified MCSA scheme (motor current signature analysis) that uses the drive rectifier input currents instead

Jesus Arellano-Padilla; Mark Sumner; Chris Gerada; Li Jing

2009-01-01

365

A soft-switching active rectifier using a concept of magnetic energy recovery switch  

Microsoft Academic Search

Converters using active switches can improve harmonic components of input current and power factor. Moreover, these converters contribute to the footprint downsizing. However, increase of switching losses and EMI due to high frequency switching is one challenge of these types of converters. This paper proposes a new active rectifier circuit topology, which can reduce the switching losses and EMI with

Yoshitsugu Miyaji; Takanori Isobe; Ryuichi Shimada

2010-01-01

366

Functional Expression and Characterization of G-protein-gated Inwardly Rectifying K+ Channels Containing GIRK3  

E-print Network

Functional Expression and Characterization of G-protein-gated Inwardly Rectifying K+ Channels and ei- ther the GIRK2 or GIRK4 subunits. However, the ho- mologous mouse brain GIRK3 clone failed of GIRK1/GIRK3 were characterized and compared to those of the GIRK1/ GIRK2 and GIRK1/GIRK4 channels. All

Clapham, David E.

367

Optimum PWM pattern for a three-phase boost DCM PFC rectifier  

Microsoft Academic Search

A lot of effort has been devoted to improving the input current THD of a three-phase single-switch boost discontinuous conduction mode (DCM) power factor correcting (PFC) rectifier. However, there is no explicit answer to the question of what the optimum solution is. In this paper, a new optimization rule is proposed by using space vector analysis. Instead of being based

Richard Zhang; Fred C. Lee

1997-01-01

368

Analysis of the dynamic and steady-state performance of Cockcroft-Walton cascade rectifiers  

Microsoft Academic Search

A detailed analysis, based on digital simulation, of the Cockcroft-Walton rectifier, including transient and steady-state voltages and currents on any component, was performed. It is shown that the numerical solution of the system may be effectively implemented by coupling the modified nodal approach formulation of the circuit equations with companion models and piecewise linear approximations of nonlinear elements. Good agreement

M. D. Bellar; E. H. Watanabe; A. C. Mesquita

1990-01-01

369

Evaluation of SiC MOSFETs for a High Efficiency Three-Phase Buck Rectifier  

E-print Network

Evaluation of SiC MOSFETs for a High Efficiency Three-Phase Buck Rectifier Fan Xu, Ben Guo, Leon M, 33 A SiC MOSFET and a 1200 V, 60 A SiC schottky barrier diode (SBD). The switching characteristics (SDBs) and Si MOSFETs is presented in [6]. The efficiency of it is 98.8%. This paper presents

Tolbert, Leon M.

370

Rectifying Orphan Components using Group-Failover in Distributed Real-time and Embedded Systems.  

E-print Network

Rectifying Orphan Components using Group-Failover in Distributed Real-time and Embedded Systems.gokhale@vanderbilt.edu ABSTRACT Orphan requests are a significant problem for multi-tier dis- tributed systems since waste resources. Orphan requests stem from the failure(s) of non-deterministic components involved

371

Current status of self rectifying air turbines for wave energy conversion  

Microsoft Academic Search

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

Toshiaki Setoguchi; Manabu Takao

2006-01-01

372

Bidirectional Transmission at the Rectifying Electrotonic Synapse: A Voltage-Dependent Process  

NASA Astrophysics Data System (ADS)

Rectifying properties of electrotonic synapses established by the crayfish giant motor fiber are associated with a more negative resting membrane potential in the presynaptic than in the postsynaptic side of the junction. An increased junctional conductance and bidirectional transmission are produced, with almost no delay, by inverting this polarization.

Giaume, Christian; Korn, Henri

1983-04-01

373

Delayed rectifier potassium currents induced in activated rat microglia set the resting membrane potential  

Microsoft Academic Search

The delayed rectifying outward K+ (IK) current was measured in lipopolysaccharide (LPS)-activated cultured rat microglial cells by using whole-cell patch clamp method. The current showed `window current' where channels were available for activation but never fully inactivated. At near resting membrane potential some part of the current was able to be activated by depolarization. Among the several K+ channel blockers

Sungkwon Chung; Eunhye Joe; Heun Soh; Moo-Yeol Lee; Hyo-Weon Bang

1998-01-01

374

Cystic Fibrosis Gene Expression is not Correlated with Rectifying Cl^- Channels  

Microsoft Academic Search

Cystic fibrosis (CF) involves a profound reduction of Cl^- permeability in several exocrine tissues. A distinctive, outwardly rectifying, depolarization-induced Cl^- channel (ORDIC channel) has been proposed to account for the Cl^- conductance that is defective in CF. The recently identified CF gene is predicted to code for a 1480-amino acid integral membrane protein termed the CF transmembrane conductance regulator (CFTR).

C. L. Ward; M. E. Krouse; D. C. Gruenert; R. R. Kopito; J. J. Wine

1991-01-01

375

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

PubMed Central

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

2014-01-01

376

Selective Formation of Size-Controlled Silicon Nanocrystals by Photosynthesis in SiO Nanoparticle Thin Film  

Microsoft Academic Search

The SiOx thin film with a thickness of about 1 mum was formed on a GaAs substrate by bar-coating with the organic solution of the SiOx nanoparticles (~40 nm). The as-formed SiOx thin film consists of the SiOx nanoparticles; thus the thin film is macroscopically discontinuous and is referred to as a nanoparticle thin film. Although there were no silicon

Changyong Chen; Seiji Kimura; Shinji Nozaki; Hiroshi Ono; Kazuo Uchida

2006-01-01

377

Specific residues of the cytoplasmic domains of cardiac inward rectifier potassium channels are effective antifibrillatory targets  

PubMed Central

Atrial and ventricular tachyarrhythmias can be perpetuated by up-regulation of inward rectifier potassium channels. Thus, it may be beneficial to block inward rectifier channels under conditions in which their function becomes arrhythmogenic (e.g., inherited gain-of-function mutation channelopathies, ischemia, and chronic and vagally mediated atrial fibrillation). We hypothesize that the antimalarial quinoline chloroquine exerts potent antiarrhythmic effects by interacting with the cytoplasmic domains of Kir2.1 (IK1), Kir3.1 (IKACh), or Kir6.2 (IKATP) and reducing inward rectifier potassium currents. In isolated hearts of three different mammalian species, intracoronary chloroquine perfusion reduced fibrillatory frequency (atrial or ventricular), and effectively terminated the arrhythmia with resumption of sinus rhythm. In patch-clamp experiments chloroquine blocked IK1, IKACh, and IKATP. Comparative molecular modeling and ligand docking of chloroquine in the intracellular domains of Kir2.1, Kir3.1, and Kir6.2 suggested that chloroquine blocks or reduces potassium flow by interacting with negatively charged amino acids facing the ion permeation vestibule of the channel in question. These results open a novel path toward discovering antiarrhythmic pharmacophores that target specific residues of the cytoplasmic domain of inward rectifier potassium channels.—Noujaim, S. F., Stuckey, J. A., Ponce-Balbuena, D., Ferrer-Villada, T., López-Izquierdo, A., Pandit, S., Calvo, C. J., Grzeda, K. R., Berenfeld, O., Sánchez Chapula, J. A., Jalife, J. Specific residues of the cytoplasmic domains of cardiac inward rectifier potassium channels are effective antifibrillatory targets. PMID:20585026

Noujaim, Sami F.; Stuckey, Jeanne A.; Ponce-Balbuena, Daniela; Ferrer-Villada, Tania; López-Izquierdo, Angelica; Pandit, Sandeep; Calvo, Conrado J.; Grzeda, Krzysztof R.; Berenfeld, Omer; Sánchez Chapula, José A.; Jalife, José

2010-01-01

378

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

PubMed Central

Background/aims To compare treatment outcomes with and without silicone oil tamponade in patients undergoing pars plana vitrectomy (PPV) for severe endogenous bacterial endophthalmitis (BEE). Methods One hundred and eight consecutive patients with severe BEE (defined by the absence of pupil red reflex at presentation and/or dense vitreous opacity on ultrasound and no improvement after 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

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

2014-01-01

379

Gamma Irradiation of Silicones  

Microsoft Academic Search

Silicones in various forms have been utilized in biomedical applications over the past several decades. While silicone elastomers\\u000a are currently the most common silicone biomaterial, low molar mass cyclic silicones, low molar mass linear silicones, silicone\\u000a oligomers, silicone polymers and silicone gels have each found applications as biomaterials. For the biomedical applications\\u000a of silicones, it is required that the materials

Aniruddha S. Palsule; Stephen J. Clarson; Christopher W. Widenhouse

2008-01-01

380

Comparing Silicone Pressure-Sensitive Adhesives to Silicone Gels for Transdermal Drug Delivery  

Microsoft Academic Search

Transdermal, drug-delivery applications mandate the use of adequate adhesive systems to not only keep the pharmaceutical agent in contact with the intended surface, but to facilitate sustained, controlled delivery. An engineer who must determine which silicone chemistry is optimal for their device has a few options. This paper will investigate the differences in silicone pressure sensitive adhesives (PSAs) and silicone

Manfred Hof; Stephen Bruner; John Freedman

381

Hydrogen-silicon carbide interactions  

NASA Technical Reports Server (NTRS)

A study of the thermochemistry and kinetics of hydrogen environmental attack of silicon carbide was conducted for temperatures in the range from 1100 C to 1400 C. Thermodynamic maps based on the parameters of pressure and oxygen/moisture content were constructed. With increasing moisture levels, four distinct regions of attack were identified. Each region is defined by the thermodynamically stable solid phases. The theoretically stable solid phases of Region 1 are silicon carbide and silicon. Experimental evidence is provided to support this thermodynamic prediction. Silicon carbide is the single stable solid phase in Region 2. Active attack of the silicon carbide in this region occurs by the formation of gases of SiO, CO, CH4, SiH4, and SiH. Analysis of the kinetics of reaction for Region 2 at 1300 C show the attack of the silicon carbide to be controlled by gas phase diffusion of H2O to the sample. Silicon carbide and silica are the stable phases common to Regions 3 and 4. These two regions are characterized by the passive oxidation of silicon carbide and formation of a protective silica layer.

Eckel, Andrew J.; Jacobson, Nathan S.; Misra, Ajay K.; Humphrey, Donald L.

1989-01-01

382

A Universal Vector Controller for Four-Quadrant Three-Phase Power Converters  

Microsoft Academic Search

Power factor corrected (PFC) rectifiers, active power filters (APFs), static VAR compensators (STATCOM), and grid-connected inverters (GCI) are indispensable elements in distributed generation power systems. PFC rectifiers are essential for load side harmonic and reactive power correction, APFs can suppress the harmonics generated by nonlinear loads or sources, STATCOMs can control the power flow in the grid, while GCIs are

Taotao Jin; Lihua Li; Keyue Ma Smedley

2007-01-01

383

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

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

384

Aviram-Ratner rectifying mechanism for DNA base-pair sequencing through graphene nanogaps  

NASA Astrophysics Data System (ADS)

We demonstrate that biological molecules such as Watson-Crick DNA base pairs can behave as biological Aviram-Ratner electrical rectifiers because of the spatial separation and weak hydrogen bonding between the nucleobases. We have performed a parallel computational implementation of the ab initio non-equilibrium Green’s function (NEGF) theory to determine the electrical response of graphene—base-pair—graphene junctions. The results show an asymmetric (rectifying) current-voltage response for the cytosine-guanine base pair adsorbed on a graphene nanogap. In sharp contrast we find a symmetric response for the thymine-adenine case. We propose applying the asymmetry of the current-voltage response as a sensing criterion to the technological challenge of rapid DNA sequencing via graphene nanogaps.

Agapito, Luis A.; Gayles, Jacob; Wolowiec, Christian; Kioussis, Nicholas

2012-04-01

385

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves  

NASA Astrophysics Data System (ADS)

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.

Shinohara, Naoki; Hatano, Ken

2014-11-01

386

A sub-0.3V highly efficient CMOS rectifier for energy harvesting applications  

NASA Astrophysics Data System (ADS)

This paper presents a sub-0.3V CMOS full-wave rectifier for energy harvesting devices. By adopting a body-input comparator with simple bias circuit, combining with body bias technique, the lowest input voltage amplitude can be reduced to 0.28V when using a standard CMOS 0.18µm process. Moreover, the voltage drop of negative voltage converter can be reduced to enhance the output voltage efficiency by adopting the proposed body bias technique. In combination with minimum reverse current and simple bias circuit in the proposed comparator, the proposed active rectifier can achieve the peak voltage conversion efficiency of over 96% and the maximum power efficiency of approximately 94%.

Niu, Dan; Huang, Zhangcai; Jiang, Minglu; Inoue, Yasuaki

387

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

E-print Network

, this thesis examines the cause and effects of low power factor and harmonic current in single phase rectifiers; provides a thorough review of previous correction techniques; and presents a new approach for ac to dc rectification with input power factor...

Martinez, Roberto

1994-01-01

388

75 FR 24747 - SCI, LLC/Zener-Rectifier Operations Division A Wholly Owned Subsidiary of SCI, LLC/ON...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Zener-Rectifier Operations Division A Wholly Owned Subsidiary of SCI, LLC/ON Semiconductor...Operations Division, a wholly owned subsidiary of SCI, LLC/ON Semiconductor...Operations Division, a wholly owned subsidiary of SCI, LLC/ON...

2010-05-05

389

Protein expression of G-protein inwardly rectifying potassium channels (GIRK) in breast cancer cells  

Microsoft Academic Search

BACKGROUND: Previous data from our laboratory has indicated that a functional link exists between the G-protein-coupled inwardly rectifying potassium (GIRK) channel and the beta-adrenergic receptor pathway in breast cancer cell lines, and these pathways were involved in growth regulation of these cells. Alcohol is an established risk factor for breast cancer and has been found to open GIRK. In order

Madhu S Dhar; Howard K Plummer III

2006-01-01

390

Self-powered integrated rectifier for wireless medical energy harvesting applications  

Microsoft Academic Search

This paper reports on the results of an integrated rectifier for wirelessly powered medical electronic devices. To con- siderably enhance the rectification efficiency, high-performance active diodes are incorporated. In addition, a fine cost-effective and energy-efficient back telemetry mechanism with increased robustness against physical variations in the external reader and internal transponder (implant) has been equipped. Fabricated in a 0.18-?? m

Cihun-Siyong Alex Gong; Muh-Tian Shiue; Yung-Pin Lee; Kai-Wen Yao

2011-01-01

391

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

Microsoft Academic Search

Six-phase double-star armature windings of a synchronous generator are essentially equivalent to 12-phase symmetrical windings displaced in turn by 30deg. This paper proposes and implements a new permanent-magnet brushless dc (BLDC) generator using 12-phase half-wave rectifier. Characteristic of output voltage is analyzed according to the star graph of slot potential, and the design constraints of armature windings are provided. Simulation

Zhuoran Zhang; Yangguang Yan; Shanshui Yang; Zhou Bo

2009-01-01

392

Organic semiconductors: rectifying electrical noise with an ionic-organic ratchet (adv. Mater. 12/2015).  

PubMed

An ionic-organic ratchet transforms electronic noise into DC current. The image displays a mechanical ratchet mechanism representing the rectifying junction of the electronic device. As described by O. V. Mikhnenko, S. D. Collins, and T.-Q. Nguyen on page 2007, This device delivers large electronic currents that are relevant for energy-harvesting applications including radio-frequency identification tags. PMID:25800625

Mikhnenko, Oleksandr V; Collins, Samuel D; Nguyen, Thuc-Quyen

2015-03-01

393

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

Microsoft Academic Search

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

Chang-Ming Liaw; Thin-Huo Chen

2000-01-01

394

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

Microsoft Academic Search

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

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

1991-01-01

395

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

Microsoft Academic Search

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

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

1989-01-01

396

Rectifying behaviors introduced by nitrogen-vacancy complex in spiral chirality single walled carbon nanotube device  

NASA Astrophysics Data System (ADS)

By applying nonequilibrium Green's functions in combination with density-functional theory, the effects of nitrogen-vacancy complex on electronic transport properties are investigated in spiral chirality single walled carbon nanotube device. The results show that rectifying behaviors can be tuned by introducing the complex defects with vacancy and nitrogen atoms. Moreover, current-voltage characteristics and negative differential conductance behavior can also be observed in this model. The mechanisms for these interesting phenomena are suggested.

Cheng, Caiping; Hu, Huifang; Wei, Yan; Zhang, Zhaojin; Wang, Xiaowei; Zhao, Juan; Peng, Ping

2013-08-01

397

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

Microsoft Academic Search

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

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

2007-01-01

398

Naringin directly activates inwardly rectifying potassium channels at an overlapping binding site to tertiapin-Q  

PubMed Central

BACKGROUND G protein-coupled inwardly rectifying potassium (KIR3) channels are important proteins that regulate numerous physiological processes including excitatory responses in the CNS and the control of heart rate. Flavonoids have been shown to have significant health benefits and are a diverse source of compounds for identifying agents with novel mechanisms of action. EXPERIMENTAL APPROACH The flavonoid glycoside, naringin, was evaluated on recombinant human KIR3.1–3.4 and KIR3.1–3.2 expressed in Xenopus oocytes using two-electrode voltage clamp methods. In addition, we evaluated the activity of naringin alone and in the presence of the KIR3 channel blocker tertiapin-Q (0.5 nM, 1 nM and 3 nM) at recombinant KIR3.1–3.4 channels. Site-directed mutagenesis was used to identify amino acids within the M1–M2 loop of the KIR3.1F137S mutant channel important for naringin's activity. KEY RESULTS Naringin (100 µM) had minimal effect on uninjected oocytes but activated KIR3.1–3.4 and KIR3.1–3.2 channels. The activation by naringin of KIR3.1–3.4 channels was inhibited by tertiapin-Q in a competitive manner. An alanine-scan performed on the KIR3.1F137S mutant channel, replacing one by one aromatic amino acids within the M1–M2 loop, identified tyrosines 148 and 150 to be significantly contributing to the affinity of naringin as these mutations reduced the activity of naringin by 20- and 40-fold respectively. CONCLUSIONS AND IMPLICATIONS These results show that naringin is a direct activator of KIR3 channels and that tertiapin-Q shares an overlapping binding site on the KIR3.1–3.4. This is the first example of a ligand that activates KIR3 channels by binding to the extracellular M1–M2 linker of the channel. PMID:21391982

Yow, Tin T; Pera, Elena; Absalom, Nathan; Heblinski, Marika; Johnston, Graham AR; Hanrahan, Jane R; Chebib, Mary

2011-01-01

399

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

400

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

PubMed

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

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

2014-08-13

401

L-364,373 fails to activate the slow delayed rectifier K + current in canine ventricular cardiomyocytes  

Microsoft Academic Search

Activators of the slow delayed rectifier K+ current (IKs) are promising tools to suppress ventricular arrhythmias originating from prolongation of action potentials. A recently synthesized\\u000a compound, L-364,373, was shown to activate IKs in ventricular cells isolated from guinea pigs and rabbits. Due to the interspecies differences known to exist in the properties\\u000a of the delayed rectifier K+ currents, the effect

János Magyar; Balázs Horváth; Tamás Bányász; Norbert Szentandrássy; Péter Birinyi; András Varró; Zsolt Szakonyi; Ferenc Fülöp; Péter P. Nánási

2006-01-01

402

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

Microsoft Academic Search

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

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

1993-01-01

403

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

PubMed Central

A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2?m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200??m and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump. PMID:24404051

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

2013-01-01

404

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

PubMed

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

Kabra, Vinay; Aamir, Lubna; Malik, M M

2014-01-01

405

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

NASA Astrophysics Data System (ADS)

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.

Takeuchi, Tsunehiro; Goto, Hiroki; Nakayama, Ryu-suke; Terazawa, Yu-ichi; Ogawa, Koto; Yamamoto, Akio; Itoh, Takashi; Mikami, Masashi

2012-05-01

406

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

PubMed Central

Summary A low cost, highly rectifying, nano heterojunction (p-ZnO/n-Si) diode was fabricated using solution-processed, p-type, ZnO nanoparticles and an n-type Si substrate. p-type ZnO nanoparticles were synthesized using a chemical synthesis route and characterized by XRD and a Hall effect measurement system. The device was fabricated by forming thin film of synthesized p-ZnO nanoparticles on an n-Si substrate using a dip coating technique. The device was then characterized by 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

Kabra, Vinay; Malik, M M

2014-01-01

407

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

SciTech Connect

Highlights: {yields} We examined allosteric control of K{sup +} channel gating. {yields} We identified a high-affinity site for Cd{sup 2+} to inhibit Kir3.2 activity. {yields} The 6-coordination geometry supports the binding. {yields} Cd{sup 2+} inhibits Kir3.2 by trapping the conformation in the closed state. -- Abstract: The gate at the pore-forming domain of potassium channels is allosterically controlled by a stimulus-sensing domain. Using Cd{sup 2+} as a probe, we examined the structural elements responsible for gating in an inward-rectifier K{sup +} channel (Kir3.2). One of four endogenous cysteines facing the cytoplasm contributes to a high-affinity site for inhibition by internal Cd{sup 2+}. Crystal structure of its cytoplasmic domain in complex with Cd{sup 2+} reveals that octahedral coordination geometry supports the high-affinity binding. This mode of action causes the tethering of the N-terminus to CD loop in the stimulus-sensing domain, suggesting that their conformational changes participate in gating and Cd{sup 2+} inhibits Kir3.2 by trapping the conformation in the closed state like 'inverse agonist'.

Inanobe, Atsushi, E-mail: inanobe@pharma2.med.osaka-u.ac.jp [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan) [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan); Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka (Japan); Matsuura, Takanori [Laboratory of Protein Informatics, Institute for Protein Research, Osaka University, Osaka (Japan)] [Laboratory of Protein Informatics, Institute for Protein Research, Osaka University, Osaka (Japan); Nakagawa, Atsushi [Laboratory of Supramolecular Crystallography, Institute for Protein Research, Osaka University, Osaka (Japan)] [Laboratory of Supramolecular Crystallography, Institute for Protein Research, Osaka University, Osaka (Japan); Kurachi, Yoshihisa, E-mail: ykurachi@pharma2.med.osaka-u.ac.jp [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan) [Department of Pharmacology, Graduate School of Medicine, Osaka University, Osaka (Japan); Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka (Japan)

2011-04-08

408

Strain controlled growth of crack-free GaN with low defect density on silicon (1 1 1) substrate  

NASA Astrophysics Data System (ADS)

We demonstrate the growth of 4.5 ?m thick gallium nitride on 100 mm diameter silicon (1 1 1) substrate using metal-organic chemical vapor deposition. For strain engineering an aluminum nitride buffer and several interlayers were applied. The realized gallium nitride layer-stack is crack-free. Several characterization methods were applied to study the crystalline quality. In X-ray diffraction measurements the full width at half maximum of the (0 0 2) reflection was found to be as low as 400?, whereas the (2 0 1) reflection showed a full width at half maximum of 580?. For verification transmission electron microscopy examinations were performed to determine the structural quality. A comparison to gallium nitride, grown on sapphire, is made.

Drechsel, P.; Riechert, H.

2011-01-01

409

Use of neural network method to characterize pressure controlled charge density of silicon nitride films deposited by PECVD  

NASA Astrophysics Data System (ADS)

A prediction model of charge density of silicon nitride (SiN) films was constructed by using a generalized regression neural network (GRNN). The SiN film was deposited by a plasma enhanced chemical vapor deposition (PECVD) system and the deposition process was characterized by means of a statistical experiment. The prediction performance of GRNN was optimized by using a genetic algorithm (GA) and yielded an improved prediction of about 63% over statistical regression model. The optimized model was utilized to qualitatively investigate the effect of process parameters under various pressures. A refractive index model was effectively utilized to validate charge density variations. For the variations in process parameters, charge density was strongly dependent on [N-H]. Effects of NH 3 or SiH 4 flow rates were significant only under high collision rate. Effect of pressure-induced collision rate was noticeable only at higher NH 3 flow rate or lower SiH 4 flow rate.

Kim, Byungwhan; Kim, Su Yeon

2008-05-01

410

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.

411

Photocatalytic Properties of Porous Silicon Nanowires  

PubMed Central

Porous silicon nanowires are synthesized through metal assisted wet-chemical etch of highly-doped silicon wafer. The resulted porous silicon nanowires exhibit a large surface area of 337 m2·g?1 and a wide spectrum absorption across the entire ultraviolet, visible and near infrared regime. We further demonstrate that platinum nanoparticles can be loaded onto the surface of the porous silicon nanowires with controlled density. These combined advancements make the porous silicon nanowires an interesting material for photocatalytic applications. We show that the porous silicon nanowires and platinum nanoparticle loaded porous silicon nanowires can be used as effective photocatalysts for photocatalytic degradation of organic dyes and toxic pollutants under visible irradiation, and thus are of significant interest for organic waste treatment and environmental remediation. PMID:22190767

Qu, Yongquan; Zhong, Xing; Li, Yujing; Liao, Lei; Huang, Yu; Duan, Xiangfeng

2010-01-01

412

Long-term stability of neural prosthetic control signals from silicon cortical arrays in rhesus macaque motor cortex  

Microsoft Academic Search

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

Cynthia A. Chestek; Vikash Gilja; Paul Nuyujukian; Justin D. Foster; Joline M. Fan; Matthew T. Kaufman; Mark M. Churchland; Zuley Rivera-Alvidrez; John P. Cunningham; Stephen I. Ryu; Krishna V. Shenoy

2011-01-01

413

Power electronics and motor control  

Microsoft Academic Search

Offering an introduction to power electronics, this text considers the topics of analogue electronics, electric motor control, and adjustable speed electrical drives, both a.c. and d.c. Up-to-date in its coverage of this rapidly developing field, the book examines such topics as controlled bridge rectifiers and speed control of induction motors by variable voltage-variable frequency inverters.

W. Shepherd; L. N. Hulley

1987-01-01

414

Silicon micromachined SCALED technology  

Microsoft Academic Search

Silicon micromachining technology will play an important role in the fabrication of high-bandwidth servo controlled microelectromechanical (mechatronic) components for super-compact disk drives. At the University of California, Los Angeles, and the California Institute of Technology, for the last three years, we have initiated a number of industry-supported joint research projects to develop the necessary technology building blocks for an integrated

Denny K. Miu; Yu-Chong Tai

1995-01-01

415

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

E-print Network

], [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

Paris-Sud XI, Université de

416

Damage Mechanisms and Controlled Crack Propagation in a Hot Pressed Silicon Nitride Ceramic. Ph.D. Thesis - Northwestern Univ., 1993  

NASA Technical Reports Server (NTRS)

The subcritical growth of cracks from pre-existing flaws in ceramics can severely affect the structural reliability of a material. The ability to directly observe subcritical crack growth and rigorously analyze its influence on fracture behavior is important for an accurate assessment of material performance. A Mode I fracture specimen and loading method has been developed which permits the observation of stable, subcritical crack extension in monolithic and toughened ceramics. The test specimen and procedure has demonstrated its ability to generate and stably propagate sharp, through-thickness cracks in brittle high modulus materials. Crack growth for an aluminum oxide ceramic was observed to be continuously stable throughout testing. Conversely, the fracture behavior of a silicon nitride ceramic exhibited crack growth as a series of subcritical extensions which are interrupted by dynamic propagation. Dynamic initiation and arrest fracture resistance measurements for the silicon nitride averaged 67 and 48 J/sq m, respectively. The dynamic initiation event was observed to be sudden and explosive. Increments of subcritical crack growth contributed to a 40 percent increase in fracture resistance before dynamic initiation. Subcritical crack growth visibly marked the fracture surface with an increase in surface roughness. Increments of subcritical crack growth loosen ceramic material near the fracture surface and the fracture debris is easily removed by a replication technique. Fracture debris is viewed as evidence that both crack bridging and subsurface microcracking may be some of the mechanisms contributing to the increase in fracture resistance. A Statistical Fracture Mechanics model specifically developed to address subcritical crack growth and fracture reliability is used together with a damaged zone of material at the crack tip to model experimental results. A Monte Carlo simulation of the actual experiments was used to establish a set of modeling input parameters. It was demonstrated that a single critical parameter does not characterize the conditions required for dynamic initiation. Experimental measurements for critical crack lengths, and the energy release rates exhibit significant scatter. The resulting output of the model produces good agreement with both the average values and scatter of experimental measurements.

Calomino, Anthony Martin

1994-01-01

417

Stress-induced glucocorticoid signaling remodels neurovascular coupling through impairment of cerebrovascular inwardly rectifying K+ channel function  

PubMed Central

Studies of stress effects on the brain have traditionally focused on neurons, without considering the cerebral microcirculation. Here we report that stress impairs neurovascular coupling (NVC), the process that matches neuronal activity with increased local blood flow. A stressed phenotype was induced in male rats by administering a 7-d heterotypical stress paradigm. NVC was modeled by measuring parenchymal arteriole (PA) vasodilation in response to neuronal stimulation in amygdala brain slices. After stress, vasodilation of PAs to neuronal stimulation was greatly reduced, and dilation of isolated PAs to external K+ was diminished, suggesting a defect in smooth muscle inwardly rectifying K+ (KIR) channel function. Consistent with these observations, stress caused a reduction in PA KIR2.1 mRNA and smooth muscle KIR current density, and blocking KIR channels significantly inhibited NVC in control, but not in stressed, slices. Delivery of corticosterone for 7 d (without stressors) or RU486 (before stressors) mimicked and abrogated NVC impairment by stress, respectively. We conclude that stress causes a glucocorticoid-mediated decrease in functional KIR channels in amygdala PA myocytes. This renders arterioles less responsive to K+ released from astrocytic endfeet during NVC, leading to impairment of this process. Because the fidelity of NVC is essential for neuronal health, the impairment characterized here may contribute to the pathophysiology of brain disorders with a stress component. PMID:24808139

Longden, Thomas A.; Dabertrand, Fabrice; Hill-Eubanks, David C.; Hammack, Sayamwong E.; Nelson, Mark T.

2014-01-01

418

Molecular and functional characterization of Anopheles gambiae inward rectifier potassium (Kir1) channels: a novel role in egg production.  

PubMed

Inward rectifier potassium (Kir) channels play essential roles in regulating diverse physiological processes. Although Kir channels are encoded in mosquito genomes, their functions remain largely unknown. In this study, we identified the members of the Anopheles gambiae Kir gene family and began to investigate their function. Notably, we sequenced the A. gambiae Kir1 (AgKir1) gene and showed that it encodes all the canonical features of a Kir channel: an ion pore that is composed of a pore helix and a selectivity filter, two transmembrane domains that flank the ion pore, and the so-called G-loop. Heterologous expression of AgKir1 in Xenopus oocytes revealed that this gene encodes a functional, barium-sensitive Kir channel. Quantitative RT-PCR experiments then showed that relative AgKir1 mRNA levels are highest in the pupal stage, and that AgKir1 mRNA is enriched in the adult ovaries. Gene silencing of AgKir1 by RNA interference did not affect the survival of female mosquitoes following a blood meal, but decreased their egg output. These data provide evidence for a new role of Kir channels in mosquito fecundity, and further validates them as promising molecular targets for the development of a new class of mosquitocides to be used in vector control. PMID:24855023

Raphemot, Rene; Estévez-Lao, Tania Y; Rouhier, Matthew F; Piermarini, Peter M; Denton, Jerod S; Hillyer, Julián F

2014-08-01

419

Silicon Nanowire Devices  

NASA Astrophysics Data System (ADS)

Metal-catalyzed, self-assembled, one-dimensional semiconductor nanowires are being considered as possible device elements to augment and supplant conventional electronics and to extend the use of CMOS beyond the physical and economic limits of conventional technology. Such nanowires can create nanostructures without the complexity and cost of extremely fine scale lithography. The well-known and controllable properties of silicon make silicon nanowires especially attractive. Easy integration with conventional electronics will aid their acceptance and incorporation. For example, connections can be formed to both ends of a nanowire by growing it laterally from a vertical surface formed by etching the top silicon layer of a silicon-on-insulator structure into isolated electrodes. Field-effect structures are one class of devices that can be readily built in silicon nanowires. Because the ratio of surface to volume in a thin nanowire is high, conduction through the nanowire is very sensitive to surface conditions, making it effective as the channel of a field-effect transistor or as the transducing element of a gas or chemical sensor. As the nanowire diameter decreases, a greater fraction of the mobile charge can be modulated by a given external charge, increasing the sensitivity. Having the gate of a nanowire transistor completely surround the nanowire also enhances the sensitivity. For a field-effect sensor to be effective, the charge must be physically close to the nanowire so that the majority of the compensating charge is induced in the nanowire and so that ions in solution do not screen the charge. Because only induced charge is being sensed, a coating that selectively binds the target species should be added to the nanowire surface to distinguish between different species in the analyte. The nanowire work at Hewlett-Packard Laboratories was supported in part by the Defense Advanced Research Projects Agency.

Kamins, Theodore

2006-03-01

420

Rectified motion in an asymmetric channel: The role of hydrodynamic interactions with walls  

NASA Astrophysics Data System (ADS)

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.

Golshaei, Behzad; Najafi, Ali

2015-02-01

421

High Precision HalfWave Rectifier Circuit In Dual Phase Output Mode  

E-print Network

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.

Jamjaem, Theerayut

2010-01-01

422

Riesz $s$-equilibrium measures on $d$-rectifiable sets as $s$ approaches $d$  

E-print Network

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.

M. T. Calef; D. P. Hardin

2008-08-28

423

Rectified motion in an asymmetric channel: the role of hydrodynamic interactions with walls  

E-print Network

Dynamics of a Brownian particle in an asymmetric micro-channel that is subjected to an external oscillating force is numerically analyzed. In addition to the elastic collisions with the walls that are kind of short range interactions, the long range hydrodynamic influences of the walls have been considered. We demonstrate how the geometrical parameters of the channel change the rectified current of the particle. As a result of numerical calculations, we show that long range hydrodynamic interactions with walls, decrease the efficiency of the Brownian ratchet.

B. Golshaei; A. Najafi

2014-09-28

424

Rectifying performance and negative differential behavior in graphite—chain—carbon nanotube junctions  

SciTech Connect

In this paper, the (5, 5) capped carbon nanotubes (CNTs) in contact with different lengths of sp monoatomic chains grown on the surface of graphite substrate are fabricated and its electronic transport properties sandwiched between CNT and graphite electrodes are investigated. The first-principles calculations based on nonequilibrium Green's function in combination with density-functional theory show that their rectifying performance and negative differential resistance behavior are observed under very low biases and obviously are enhanced when the length increases. From our analysis, the charge transfer, transmission spectra, projected density of states and evolutions of molecular orbitals are responsible for these phenomena.

Qiu, Ming [Department of Mechanical Engineering, University of Wisconsin, Milwaukee, Wisconsin 53211 (United States); School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Li, Jiangfan [School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Liew, K. M., E-mail: kmliew@cityu.edu.hk [Department of Civil and Architectural Engineering, City University of Hong Kong, Kowloon (Hong Kong); Yuan, Chris, E-mail: cyuan@uwm.edu [Department of Mechanical Engineering, University of Wisconsin, Milwaukee, Wisconsin 53211 (United States)

2014-01-13

425

Enhancing the photoelectric effect with a potential-programmed molecular rectifier.  

PubMed

Dendrimer-based electron rectifiers were applied to photoconducting devices. A remarkable enhancement of the photocurrent response was observed when a zinc porphyrin as the photosensitizer was embedded in the dendritic phenylazomethine (DPA) architecture. The dendrimer-based sensitizer exhibited a 20-fold higher current response than the non-dendritic zinc porphyrin. In sharp contrast, a similar application of the dendrimer with poly(vinylcarbazole) as the electron donor resulted in a decreased response. This is consistent with the idea that the DPA facilitates electron transfer from the core to its periphery along a potential gradient, as predicted by density functional theory calculations. PMID:22568570

Imaoka, Takane; Ueda, Hiroaki; Yamamoto, Kimihisa

2012-05-23

426

Modification of materials to decrease of quantity of radiation defects in an implanted-heterojunction rectifier  

NASA Astrophysics Data System (ADS)

It has been recently shown that manufacturing of an implanted-junction rectifier in a semiconductor heterostructure for optimal relationship between energy of implanted ions, materials and thicknesses of layers of the heterostructure (H) after annealing of radiation defects gives us possibility to increase sharpness of p-n-junction and at the same time to increasing of homogeneity of dopant distribution in the doped area (Pankratov, Phys Lett A 372(11):1897, 2008; Proc SPIE 7521:75211D, 2010a, b). In this paper we consider a possibility to decrease quantity of radiation defects, which were generated during ion implantation, using porous epitaxial layers of the heterostructure.

Pankratov, E. L.; Bulaeva, E. A.

2013-08-01

427

Assignment of the human hippocampal inward rectifier potassium channel (HIR) gene to 22q13.1  

SciTech Connect

The HIR gene encodes a small-conductance inward rectifier potassium channel (HIR or K{sub IR}2.3) that is found in heart and brain. Inward rectifiers are a specialized class of potassium channels that produce large inward currents at potentials negative to the potassium equilibrium potential and only small outward currents at more positive potentials. This asymmetry in K{sup +} conductance plays a key role in the excitability of muscle cells and neurons. Inward rectifier potassium channels are the major contributors to the basal potassium conductance in cardiac muscle, where their role is to modulate cell excitability and heart beat frequency, maintain the resting potential, and terminate the long-duration cardiac action potentials. In the central nervous system, inward rectifiers are involved in similar aspects of the modulation of cell excitability. The central role of inward rectifiers in cardiac and neuronal function suggest that they might be involved in the etiology of human cardiovascular and neurological diseases. 11 refs., 2 figs.

Budarf, M.L.; Barnoski, B.L.; Bell, C.J. [Children`s Hospital of Philadelphia, PA (United States)] [and others] [Children`s Hospital of Philadelphia, PA (United States); and others

1995-04-10

428

Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier  

PubMed Central

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

Tsai, Cheng-Tao; Tseng, Sheng-Yu

2013-01-01

429

Silicon Micromachined Microlens Array for THz Antennas  

NASA Technical Reports Server (NTRS)

5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a smooth curvature. The measured height of the silicon microlens is about 280 microns. In this case, the original height of the photoresist was 210 microns. The change was due to the etching selectivity of 1.33 between photoresist and silicon. The measured surface roughness of the silicon microlens shows the peak-to-peak surface roughness of less than 0.5 microns, which is adequate in THz frequency. For example, the surface roughness should be less than 7 microns at 600 GHz range. The SEM (scanning electron microscope) image of the microlens confirms the smooth surface. The beam pattern at 550 GHz shows good directivity.

Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

2013-01-01

430

High Performance Silicon Nanowire Field Effect Transistors  

Microsoft Academic Search

Silicon nanowires can be prepared with single-crystal structures, diameters as small as several nanometers and controllable hole and electron doping, and thus represent powerful building blocks for nanoelectronics devices such as field effect transistors. To explore the potential limits of silicon nanowire transistors, we have examined the influence of source-drain contact thermal annealing and surface passivation on key transistor properties.

Yi Cui; Zhaohui Zhong; Deli Wang; Wayne U. Wang; Charles M. Lieber

2003-01-01

431

Novel micromachined silicon sensor for continuous glucose monitoring  

Microsoft Academic Search

The construction and the application properties of a micromachined silicon sensor for continuous glucose monitoring are presented. The sensor uses the conventional enzymatic conversion of glucose with amperometric detection of H2O2. The innovation is the precise diffusion control of the analyte through a porous silicon membrane into a silicon etched cavity containing the immobilised enzyme. A variation of the number

G. Piechotta; J. Albers; R. Hintsche

2005-01-01

432

Suprachiasmatic nucleus function and circadian entrainment are modulated by G protein-coupled inwardly rectifying (GIRK) channels.  

PubMed

G protein signalling within the central circadian oscillator, the suprachiasmatic nucleus (SCN), is essential for conveying time-of-day information. We sought to determine whether G protein-coupled inwardly rectifying potassium channels (GIRKs) modulate SCN physiology and circadian behaviour. We show that GIRK current and GIRK2 protein expression are greater during the day. Pharmacological inhibition of GIRKs and genetic loss of GIRK2 depolarized the day-time resting membrane potential of SCN neurons compared to controls. Behaviourally, GIRK2 knockout (KO) mice failed to shorten free running period in response to wheel access in constant darkness and entrained more rapidly to a 6 h advance of a 12 h:12 h light-dark (LD) cycle than wild-type (WT) littermate controls. We next examined whether these effects were due to disrupted signalling of neuropeptide Y (NPY), which is known to mediate non-photic phase shifts, attenuate photic phase shifts and activate GIRKs. Indeed, GIRK2 KO SCN slices had significantly fewer silent cells in response to NPY, likely contributing to the absence of NPY-induced phase advances of PER2::LUC rhythms in organotypic SCN cultures from GIRK2 KO mice. Finally, GIRK channel activation is sufficient to cause a non-photic-like phase advance of PER2::LUC rhythms on a Per2(Luc+/-) background. These results suggest that rhythmic regulation of GIRK2 protein and channel function in the SCN contributes to day-time resting membrane potential, providing a mechanism for the fine tuning responses to non-photic and photic stimuli. Further investigation could provide insight into disorders with circadian disruption comorbidities such as epilepsy and addiction, in which GIRK channels have been implicated. PMID:25217379

Hablitz, L M; Molzof, H E; Paul, J R; Johnson, R L; Gamble, K L

2014-11-15

433

High-performance microfluidic rectifier based on sudden expansion channel with embedded block structure.  

PubMed

A high-performance microfluidic rectifier incorporating a microchannel and a sudden expansion channel is proposed. In the proposed device, a block structure embedded within the expansion channel is used to induce two vortex structures at the end of the microchannel under reverse flow conditions. The vortices reduce the hydraulic diameter of the microchannel and, therefore, increase the flow resistance. The rectification performance of the proposed device is evaluated by both experimentally and numerically. The experimental and numerical values of the rectification performance index (i.e., the diodicity, Di) are found to be 1.54 and 1.76, respectively. Significantly, flow rectification is achieved without the need for moving parts. Thus, the proposed device is ideally suited to the high pressure environment characteristic of most micro-electro-mechanical-systems (MEMS)-based devices. Moreover, the rectification performance of the proposed device is superior to that of existing valveless rectifiers based on Tesla valves, simple nozzle/diffuser structures, or cascaded nozzle/diffuser structures. PMID:22655019

Tsai, Chien-Hsiung; Lin, Che-Hsin; Fu, Lung-Ming; Chen, Hui-Chun

2012-06-01

434

Rectifier of aberrant mRNA splicing recovers tRNA modification in familial dysautonomia.  

PubMed

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

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

435

-based RRAM cell structure with rectifying characteristics by integrating Ni/n + -Si diode  

NASA Astrophysics Data System (ADS)

A simplified one-diode one-resistor (1D1R) resistive switching memory cell that uses only four layers of TaN/ZrTiO x /Ni/n+-Si was proposed to suppress sneak current where TaN/ZrTiO x /Ni can be regarded as a resistive-switching random access memory (RRAM) device while Ni/n+-Si acts as an Schottky diode. This is the first RRAM cell structure that employs metal/semiconductor Schottky diode for current rectifying. The 1D1R cell exhibits bipolar switching behavior with SET/RESET voltage close to 1 V without requiring a forming process. More importantly, the cell shows tight resistance distribution for different states, significantly rectifying characteristics with forward/reverse current ratio higher than 103 and a resistance ratio larger than 103 between two states. Furthermore, the cell also displays desirable reliability performance in terms of long data retention time of up to 104 s and robust endurance of 105 cycles. Based on the promising characteristics, the four-layer 1D1R structure holds the great potential for next-generation nonvolatile memory technology.

Lin, Chia-Chun; Wu, Yung-Hsien; Chang, You-Tai; Sun, Cherng-En

2014-05-01

436

Suppression of Floating Body Effects by Controlling Potential Profile in the Lower Body Region of Silicon-on-Insulator Metal-Oxide-Semiconductor Field Effect Transistors  

NASA Astrophysics Data System (ADS)

This paper describes a promising way to suppress floating body effects (FBE) in fully depleted (FD) silicon-on-insulator metal-oxide-semiconductor field-effect transistors (SOI MOSFETs), which is applicable to the complementary MOS (CMOS) structure. The FBE is suppressed by controlling the potential profile by supplying an adequate positive substrate voltage (VSUB). FD SOI NMOSFETs show a strong dependence of VT on VD in the higher VD range, which is induced by the FBE@. The accumulation in the body of holes generated through impact ionization raises the body potential, and hence lowers VT. A positive VSUB improves the anomalous subthreshold slope, and thereby weakens the dependence of VT on VD. This is mainly because the positive VSUB lowers the potential barrier height for holes in the lower body region, which enhances the flow of holes in the body into the source, and thus suppresses the increase in body potential. The decrease in the potential barrier height for holes is supported by two-dimensional device simulation. Supplying a positive VSUB causes hardly any changes in the characteristics of SOI P-channel MOSFETs (PMOSFETs). Therefore, supplying a positive voltage to the substrate is useful for the SOI CMOS structure.

Sato, Yasuhiro; Tsuchiya, Toshiaki

2000-06-01

437

A tetraethylammonium-insensitive inward rectifier K+ channel in Müller cells of the turtle (Pseudemys scripta elegans) retina.  

PubMed

Ion channels present in isolated glial (Müller) cells from the retina of the turtle (Pseudemys scripta elegans) were studied with the patch clamp technique. The predominant conductance in these cells was due to an inward rectifying potassium current. The whole-cell conductance of the inward rectifier was 20.2 +/- 1.9 nS (n = 7 cells) in a standard extracellular saline solution (3 mM extracellular potassium). This conductance was dependent on the extracellular potassium concentration, with a 2.88-fold change in conductance per tenfold shift in concentration. The relative permeability sequence to potassium of the inward rectifier was found to be: potassium (1.0) > rubidium (0.7) > ammonium (0.2) > lithium (0.1) = sodium (0.1), which corresponded to the Eisenman sequence IV or V for a strong-field-strength potassium binding site on the channel. The single channel conductance measured in cell-attached patches with potassium chloride (150 mM) in the pipette was 68.5 +/- 6.0 pS (n = 3 patches). The inward rectifier current was not blocked by extracellular tetraethylammonium (TEA+, 20 mM), but was blocked by extracellular barium (5 mM) or cesium (5 mM). The TEA+ insensitivity of the inward rectifier potassium channel in Müller cells is unusual, given that this type of channel in most excitable cells is sensitive to micromolar concentrations of this compound, and may be a characteristic of inward rectifier potassium channels that are primarily involved with extracellular potassium regulation. PMID:7807523

Le Dain, A C; Anderton, P J; Martin, D K; Millar, T J

1994-09-01

438

Dual Mode Inverter Control Test Verification  

SciTech Connect

Permanent Magnet Motors with either sinusoidal back emf (permanent magnet synchronous motor [PMSM]) or trapezoidal back emf (brushless dc motor [BDCM]) do not have the ability to alter the air gap flux density (field weakening). Since the back emf increases with speed, the system must be designed to operate with the voltage obtained at its highest speed. Oak Ridge National Laboratory's (ORNL) Power Electronics and Electric Machinery Research Center (PEEMRC) has developed a dual mode inverter controller (DMIC) that overcomes this disadvantage. This report summarizes the results of tests to verify its operation. The standard PEEMRC 75 kW hard-switched inverter was modified to implement the field weakening procedure (silicon controlled rectifier enabled phase advance). A 49.5 hp motor rated at 2800 rpm was derated to a base of 400 rpm and 7.5 hp. The load developed by a Kahn Industries hydraulic dynamometer, was measured with a MCRT9-02TS Himmelstein and Company torque meter. At the base conditions a current of 212 amperes produced the 7.5 hp. Tests were run at 400, 1215, and 2424 rpm. In each run, the current was no greater than 214 amperes. The horsepower obtained in the three runs were 7.5, 9.3, and 8.12. These results verified the basic operation of the DMIC in producing a Constant Power Speed Ratios (CPSR) of six.

Bailey, J.M.

2001-04-25

439

Degradation in silicon solar cells caused by the formation of Schottky barrier contacts during accelerated testing  

SciTech Connect

When p+/n silicon solar cells having a lightly doped substrate, i.e. no back surface field, were subjected to accelerated stress testing an irregularity occurred in the VI characteristic along with the resulting loss of power output. Evidence is presented which indicates that this is due to formation of a rectifying Schottky barrier between the back metal contact and the silicon, possibly as a result of the dissociation of water vapor molecules and the subsequent diffusion of hydrogen to the metal-silicon interface. When encapsulated cells were stressed, those having a steel substrate showed less degradation than unencapsulated cells while those with Tedlar or foil substrates showed more. This rather surprising result can also be explained in terms of the hydrogen diffusion phenomenon.

Lathrop, J.W.; Davis, C.W.; Misiakos, K.

1984-05-01

440

Long-term stability of neural prosthetic control signals from silicon cortical arrays in rhesus macaque motor cortex  

NASA Astrophysics Data System (ADS)

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.

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

441

Controlled self-assembly and photovoltaic characteristics of porphyrin derivatives on a silicon surface at solid-liquid interfaces.  

PubMed

Two meso-tetraphenylporphyrin (H2TPP) derivatives with different central metal ions, namely ZnTPP, CuTPP, were synthesized, and characterized by a series of spectroscopic methods. Their self-assembly behaviors in mixed solvents without surfactant were systematically investigated. The morphology of the thus produced nanoarchitectures could be efficiently controlled. Nanoslices can be manufactured when a volume of cyclohexane is involved, octahedrons can be produced when a mixed solvent of chloroform and isopropanol is employed, while four-leaf clover-shaped structures can be produced with a large volume of methanol injected. The nanostructures have been characterized by electronic absorption, scanning electron microscopy (SEM) and photoelectric conversion techniques. The internal structures of the nanostructures are well described by XRD. The nanostructures exhibit a power conversion under illumination intensity of 2.3 mW cm(-2). The present result appears to represent an effort toward controlling the morphology of self-assembled nanostructures of porphyrin derivatives via synthesis through introduction of metal-ligand and solvent interaction. Nevertheless, the fundamental study will be helpful to understand photoinduced energy/charge transport in an organic interface and this might also serve as promising building blocks for nanoscale power sources for potential application in solar energy technologies and organic electronics and optoelectronics. PMID:24647426

Cai, Jinhua; Chen, Haihui; Huang, Jiangen; Wang, Jingxia; Tian, Dongliang; Dong, Huanli; Jiang, Lei

2014-04-21

442

Vibrations Would Induce Flow In Molten Silicon  

NASA Technical Reports Server (NTRS)

Flow patterns and velocities controlled to improve cystals. According to proposal, intense sound used to induce flow in molten silicon to increase quality of crystals grown in shallow-melt Czochralski process.

Barmatz, M. B.; Morrison, A. D.

1988-01-01

443

Yield of silicon selective epitaxial growth and its role in the production planning and control of three-dimensional semiconductor devices  

Microsoft Academic Search

We focus on the yield (Y) and growth rate (G) of silicon selective epitaxial growth (SEG) at 820 to 970°C, and pressures between 40 and 150 Torr. Since the yield of silicon SEG is a potential bottleneck in the manufacture of three-dimensional integrated circuits, e.g., 3-D CMOS, basic knowledge of Y and its dependence on operating conditions, substrate surface parameters,

Shannon Chen; Christos Takoudis; Reha Uzsoy

1996-01-01

444

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

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

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

2009-01-01

445

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

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

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

2009-01-01

446

Silicon Web Process Development  

NASA Technical Reports Server (NTRS)

Progress in the development of techniques to grow silicon web at 25 wq cm/min output rate is reported. Feasibility of web growth with simultaneous melt replenishment is discussed. Other factors covered include: (1) tests of aftertrimmers to improve web width; (2) evaluation of growth lid designs to raise speed and output rate; (3) tests of melt replenishment hardware; and (4) investigation of directed gas flow systems to control unwanted oxide deposition in the system and to improve convective cooling of the web. Compatibility with sufficient solar cell performance is emphasized.

Duncan, C. S.; Seidensticker, R. G.; Hopkins, R. H.; Mchugh, J. P.; Hill, F. E.; Heimlich, M. E.; Driggers, J. M.

1978-01-01

447

Position control of PbS quantum dot using nanohole on silicon substrate processed by scanning probe lithography  

NASA Astrophysics Data System (ADS)

We report a method of processing of nanometer-size holes using an oxide mask drawn by scanning probe microscopy (SPM), and show that a nanohole can be used for the position control of a single colloidal quantum dot. An apertureless mask process was developed for the formation of nanometer-wide holes. The process conditions used to obtain a large slope angle at the edge of the oxide mask and high Si/oxide selectivity during dry etching were investigated to make a nanohole sufficiently deep to trap quantum dots. SPM observation suggested that a 6 nm PbS quantum dot was trapped by the smallest nanohole with a width of 10 × 18 nm2 and a depth of 5 nm.

Mukai, Kohki; Hirota, Akinobu; Nakashima, Seisuke

2015-04-01

448

Characterization of the inward-rectifying potassium current in cat ventricular myocytes  

PubMed Central

Whole-cell membrane currents were measured in isolated cat ventricular myocytes using a suction-electrode voltage-clamp technique. An inward- rectifying current was identified that exhibited a time-dependent activation. The peak current appeared to have a linear voltage dependence at membrane potentials negative to the reversal potential. Inward current was sensitive to K channel blockers. In addition, varying the extracellular K+ concentration caused changes in the reversal potential and slope conductance expected for a K+ current. The voltage dependence of the chord conductance exhibited a sigmoidal relationship, increasing at more negative membrane potentials. Increasing the extracellular K+ concentration increased the maximal level of conductance and caused a shift in the relationship that was directly proportional to the change in reversal potential. Activation of the current followed a monoexponential time course, and the time constant of activation exhibited a monoexponential dependence on membrane potential. Increasing the extracellular K+ concentration caused a shift of this relationship that was directly proportional to the change in reversal potential. Inactivation of inward current became evident at more negative potentials, resulting in a negative slope region of the steady state current-voltage relationship between -140 and -180 mV. Steady state inactivation exhibited a sigmoidal voltage dependence, and recovery from inactivation followed a monoexponential time course. Removing extracellular Na+ caused a decrease in the slope of the steady state current-voltage relationship at potentials negative to -140 mV, as well as a decrease of the conductance of inward current. It was concluded that this current was IK1, the inward-rectifying K+ current found in multicellular cardiac preparations. The K+ and voltage sensitivity of IK1 activation resembled that found for the inward- rectifying K+ currents in frog skeletal muscle and various egg cell preparations. Inactivation of IK1 in isolated ventricular myocytes was viewed as being the result of two processes: the first involves a voltage-dependent change in conductance; the second involves depletion of K+ from extracellular spaces. The voltage-dependent component of inactivation was associated with the presence of extracellular Na+. PMID:2455768

1988-01-01

449

TrkB Activation by Brain-derived Neurotrophic Factor Inhibits the G Protein-gated Inward Rectifier Kir3 by Tyrosine Phosphorylation of the Channel*  

PubMed Central

G protein-activated inwardly rectifying potassium channels (Kir3) are widely expressed throughout the brain, and regulation of their activity modifies neuronal excitability and synaptic transmission. In this study, we show that the neurotrophin brain-derived neurotrophic factor (BDNF), through activation of TrkB receptors, strongly inhibited the basal activity of Kir3. This inhibition was subunit dependent as functional homomeric channels of either Kir3.1 or Kir3.4 were significantly inhibited, whereas homomeric channels composed of Kir3.2 were insensitive. The general tyrosine kinase inhibitors genistein, Gö 6976, and K252a but not the serine/threonine kinase inhibitor staurosporine blocked the BDNF-induced inhibition of the channel. BDNF was also found to directly stimulate channel phosphorylation because Kir3.1 immunoprecipitated from BDNF-stimulated cells showed enhanced labeling by anti-phosphotyrosine-specific antibodies. The BDNF effect required specific tyrosine residues in the amino terminus of Kir3.1 and Kir3.4 channels. Mutations of either Tyr-12, Tyr-67, or both in Kir3.1 or mutation of either Tyr-32, Tyr-53, or both of Kir3.4 channels to phenylalanine significantly blocked the BDNF-induced inhibition. The insensitive Kir3.2 was made sensitive to BDNF by adding a tyrosine (D41Y) and a lysine (P32K) upstream to generate a phosphorylation site motif analogous to that present in Kir3.4. These results suggest that neurotrophin activation of TrkB receptors may physiologically control neuronal excitability by direct tyrosine phosphorylation of the Kir3.1 and Kir3.4 subunits of G protein-gated inwardly rectifying potassium channels. PMID:10833508

Rogalski, Sherri L.; Appleyard, Suzanne M.; Pattillo, Aaron; Terman, Gregory W.; Chavkin, Charles

2005-01-01

450

Tailored Electrical Driving as a Means of Controlling Heat Distribution and Convection Patterns in Joule-Heated Waste Glass Melters  

SciTech Connect

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.

Fort, James A.; Lessor, Delbert L.

2004-01-01

451

Colloidal characterization of silicon nitride and silicon carbide  

NASA Technical Reports Server (NTRS)

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.

Feke, Donald L.

1986-01-01

452

Thin silicon solar cells  

SciTech Connect

The silicon-film design achieves high performance by using a dun silicon layer and incorporating light trapping. Optimally designed thin crystalline solar cells (<50 microns thick) have performance advantages over conventional thick devices. The high-performance silicon-film design employs a metallurgical barrier between the low-cost substrate and the thin silicon layer. Light trapping properties of silicon-film on ceramic solar cells are presented and analyzed. Recent advances in process development are described here.

Hall, R.B.; Bacon, C.; DiReda, V.; Ford, D.H.; Ingram, A.E.; Cotter, J.; Hughes-Lampros, T.; Rand, J.A.; Ruffins, T.R.; Barnett, A.M. [Astro Power Inc., Solar Park, Newark, DE (United States)

1992-12-01

453

Activation and Inhibition of Neuronal G Protein-Gated Inwardly Rectifying K Channels by P2Y Nucleotide Receptors  

E-print Network

Activation and Inhibition of Neuronal G Protein-Gated Inwardly Rectifying K Channels by P2Y Nucleotide Receptors Alexander K. Filippov, Jose M. Fern ´andez-Fern ´andez, Stephen J. Marsh, Joseph SimonSADP) induced activation of GIRK current (IGIRK) followed by inhibition. In contrast, stimulation of endogenous

Brown, David

454

Peak and average rectified EMG measures: Which method of data reduction should be used for assessing core training exercises?  

Microsoft Academic Search

Core strengthening and stability exercises are fundamental for any conditioning training program. Although surface electromyography (sEMG) is used to quantify muscle activity there is a lack of research using this method to investigate the core musculature and core stability. Two types of data reduction are commonly used for sEMG; peak and average rectified EMG methods. Peak EMG has been infrequently

A. E. Hibbs; K. G. Thompson; D. N. French; D. Hodgson; I. R. Spears

2011-01-01

455

Microwave and millimeter-wave rectifying circuit arrays and ultra-wideband antennas for wireless power transmission and communications  

E-print Network

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...

Ren, Yu-Jiun

2009-05-15

456

On the role of sodium ions in the regulation of the inward-rectifying potassium conductance in cat ventricular myocytes  

Microsoft Academic Search

The conductance of the inward-rectifying K + current (IK~) in isolated cat ventricular myocytes is decreased by reducing the extracellular Na § concentra- tion. Using a whole-cell patch-clamp technique, possible mechanisms underlying this Na + dependence were investigated. These included (a) block of inward K + current by the Na + substitute, (b) changes in membrane surface charge associated with

ROBERT D. HARVEY; ROBERT E. TEN EICK

1989-01-01

457

Heat and mass transfer analysis of a helical coil rectifier in an ammonia–water absorption system  

Microsoft Academic Search

This paper presents a detailed study on the ammonia–water vapour rectification process in absorption systems using a helical coil rectifier. A differential mathematical model has been developed on the basis of mass and energy balances and heat and mass transfer equations. The differential volume has been defined in each coil turn by a differential angle on the turn and a

José Fernández-Seara; Jaime Sieres; Manuel Vázquez

2003-01-01

458

Effect of guide vanes on the performance of a self-rectifying air turbine with constant and variable chord rotors  

Microsoft Academic Search

A Wells turbine is a self-rectifying air flow turbine capable of converting pneumatic power of the periodically reversing air stream in Oscillating Water Column into mechanical energy. The Wells turbine has inherent disadvantages; lower efficiency, poorer starting characteristics, higher axial force and low tangential force in comparison with conventional turbines. Guide vanes before and after the rotor suggest a means

M. Govardhan; T. S. Dhanasekaran

2002-01-01

459

Delayed rectifier potassium channels in ventricle and sinoatrial node of the guinea pig: Molecular and regulatory properties  

Microsoft Academic Search

Summary We focus on the regulatory properties of delayed rectifier K+ (IK) channels in guinea-pig sinoatrial node (SAN) and compare SAN IK to the better characterized ventricular IK. Despite demonstrated similarities in the properties of IK in guinea-pig ventricle and SAN, the possibility remains that expression of IK channels can vary regionally within the same heart. Like ventricular IK, SAN

L. C. Freeman; R. S. Kass

1993-01-01

460

Synergistic hierarchical silicone-modified polysaccharide hybrid as a soft scaffold to control cell adhesion and proliferation.  

PubMed

In this study, a new type of polydimethylsiloxane-modified chitosan (PMSC) amphiphilic hydrogel was developed as a soft substrate to explore cellular responses for dermal reconstruction. The hydrogel wettability, mechanical stiffness and topography were controllable through manipulation of the degree of esterification (DE) between hydrophobic polydimethylsiloxane (PDMS) and hydrophilic N,O-(carboxymethyl)-chitosan (NOCC). Based on microphase separation, the incorporation of PDMS into NOCC increased the stiffness of the hybrid through the formation of self-assembled aggregates, which also provided anchor sites for cell adhesion. As the DE exceeded 0.39, the size of the PDMS-rich aggregates changed from nanoscale to microscale. Subsequently, the hierarchical architecture resulted in an increase in the tensile modulus of the hybrid gel up to fourfold, which simultaneously provided mechano-topographic guidance and allowed the cells to completely spread to form spindle shapes instead of forming a spherical morphology, as on NOCC (DE=0). The results revealed that the incorporation of hydrophobic PDMS not only impeded acidic damage resulting from NOCC but also acted as an adhesion modification agent to facilitate long-term cell adhesion and proliferation on the soft substrate. As proved by the promotion on long-term type-I collagen production, the PMSC hybrid with self-assembled mechano-topography offers great promise as an advanced scaffold material for use in healing applications. PMID:24793655

Huang, Wei-Chen; Liu, Kun-Ho; Liu, Ta-Chung; Liu, Dean-Mo; Chen, San-Yuan

2014-08-01

461

Synthesis of wirelike silicon nanostructures by dispersion of silicon on insulator using electroless etching  

Microsoft Academic Search

We employ electroless etching to disperse silicon on insulator (SOI) wafers in ionic silver HF into wirelike silicon nanostructures. The procedure allows detachment of the nanowires at the oxide interface and enables easy recovery of dispersions for subsequent controlled delivery. Nanowires 10 mum long and 50-100 nm thick are demonstrated using an SOI substrate of 10 mum device thickness. Direct

Kevin Mantey; Somayeh Shams; Munir H. Nayfeh; Osama Nayfeh; Mansour Alhoshan; Salman Alrokayan

2010-01-01

462

Secondary ion mass spectrometry: Depth profiling of shallow As implants in silicon and silicon dioxide  

Microsoft Academic Search

The usefulness of secondary ion mass spectrometry as a process control tool in integrated circuit applications has been investigated. As a test case, shallow As implants (4–40 keV) in silicon and silicon dioxide are measured and the range parameters (projected range, range straggling, skewness, and kurtosis) are derived. In this work it is shown that the measurements of these shallow

W. Vandervorst; H. E. Maes; R. F. De Keersmaecker

1984-01-01

463

Inward rectifier potassium channel Kir 2.3 is inhibited by internal sulfhydryl modification.  

PubMed

Regions of the hippocampal inward rectifier potassium channel Kir 2.3 that contact the aqueous environment were investigated by identification of native cysteine residues that confer sulfhydryl reagent sensitivity to the channel conductance. Kir 2.3 currents were inhibited by N-ethylmaleimide (NEM), whereas currents of Kir 2.1 were unaffected. The reactive residues were identified as Kir 2.3 Cys28 and Cys50 using chimeric constructs and mutagenesis. These sites were not accessible to p-chloromercuriphenylsulfonate (pCMPS) applied extracellularly. However, both Cys28 and Cys50 were accessible to 2-(trimethylammoniumethyl) methanethiosulfonate (MTSET) applied to the intracellular surface of the membrane. These studies demonstrate that Cys28 and Cys50 lie in a cytoplasmic aqueous accessible region of the channel, and suggest that the channel N-terminus is a key constituent of the internal vestibule of the pore and/or modulates channel gating. PMID:10599834

Radeke, C M; Conti, L R; Vandenberg, C A

1999-11-01

464

Rectifying Performance and Negative Differential Resistance Behavior of Doping Atoms Effect in Polyphenyls  

NASA Astrophysics Data System (ADS)

The properties of two polyphenyls doped with nitrogen and boron atoms, which are connected by an alkane chain, are investigated by the non-equilibrium Green's function method combined with the density functional theory. It has been found that the doped sites have significant effects on the current-voltage characteristics. For models with the N(B) near the alkane chain, the rectification ratio is smaller, but the rectifying performance of models with the N(B) far away from the alkane chain is tremendously enhanced and rectification ratios can reach 280, alongside negative differential resistance behavior. The mechanisms for these phenomena are explained by transmission spectra, the molecular projected self-consistent Hamiltonian eigenstates, electrostatic potential distribution, and projected density of states.

Liu, Wenjiang; Cai, Shaohong; Deng, Xiaoqing

2015-02-01

465

Delayed rectifier K channels contribute to contrast adaptation in mammalian retinal ganglion cells  

PubMed Central

SUMMARY Retinal ganglion cells adapt by reducing their sensitivity during periods of high contrast. Contrast adaptation in the firing response depends on both presynaptic and intrinsic mechanisms. Here, we investigated intrinsic mechanisms for contrast adaptation in OFF Alpha ganglion cells in the in vitro guinea pig retina. Using either visual stimulation or current injection, we show that brief depolarization evoked spiking and suppressed firing during subsequent depolarization. The suppression could be explained by Na channel inactivation, as shown in salamander cells. However, brief hyperpolarization in the physiological range (5–10 mV) also suppressed firing during subsequent depolarization. This suppression was sensitive selectively to blockers of delayed-rectifier K channels (KDR). Somatic membrane patches showed TEA-sensitive KDR currents with activation near ?25 mV and removal of inactivation at voltages negative to Vrest. Brief periods of hyperpolarization apparently remove KDR inactivation and thereby increase the channel pool available to suppress excitability during subsequent depolarization. PMID:21745646

Weick, Michael; Demb, Jonathan B.

2011-01-01

466

Scanning the Topography of Polyamine Blocker Binding in an Inwardly Rectifying Potassium Channel*  

PubMed Central

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