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1

Novel and robust silicon-controlled rectifier (SCR) based devices for on-chip ESD protection  

Microsoft Academic Search

Silicon-controlled rectifiers (SCRs) are frequently used to build on-chip electrostatic discharge (ESD) protection structures, but SCRs are not sufficiently robust to meet a wide range of ESD requirements in various integrated circuits. In this paper, a novel and robust SCR-based device called the HHLVTSCR is presented. It is demonstrated that HHLVTSCR can exhibit various characteristics useful for ESD solutions. An

Javier A. Salcedo; Juin J. Liou; Joseph C. Bernier

2004-01-01

2

Achievement of digital control technology on high-power silicon controlled rectifier  

NASA Astrophysics Data System (ADS)

To fulfill the need of experimental DC supply of subway inverter, this paper designs and develops a set of rectifier system of 160kW, output voltage can be adjusted from 500V to 900V. This article uses SCR as main switches, the trigger circuit adopts digital trigger circuit, the control of whole system is achieved by DSP. The main control method is digital PI, which used to control the output DC voltage to be dynamically stable. The main circuit parameters and control method are simulated by MATLAB/Simulink. The results validate the system design.

Gao, Yinhan; Sun, Qiang; Liu, Changying

2008-10-01

3

Study of Design Factors Affecting Turn-on Time of Silicon Controlled Rectifiers (SCRS) in 90 and 65nm Bulk CMOS Technologies  

Microsoft Academic Search

We explore the effect of layout factors on the turn-on time of silicon controlled rectifiers (SCRs) in 90nm and 65nm bulk CMOS technologies. Using a very fast transmission line pulse (VFTLP) tester, we show that a SCR in 65nm bulk CMOS technology can achieve a turn-on time of 500ps with proper design. Using device simulations, we identify factors limiting SCR

James Di Sarro; Kiran Chatty; Robert Gauthier; Elyse Rosenbaum

2006-01-01

4

Controlled rectifier motor vehicle battery charger  

SciTech Connect

A conventional on-off voltage regulator, responsive to the output voltage of the rectifier of a vehicular battery charging system, operates three circuits each containing a pulse transformer and its driving transistor and other components for controlling the three SCRs that provide the negative side of the rectifier bridge, so that they will either pass entire halfwaves or block completely. The other three rectifier elements of the bridge are ordinary diodes. With this arrangement the SCRs may have the same rating as the other diodes of the bridge, and the thermal load is evenly distributed, while an alternator having a permanent magnet field can be used.

Kurz, W.

1983-07-26

5

Overcurrent protection control technique of ZCS series resonant rectifier  

Microsoft Academic Search

An overcurrent protection control technique for a zero current switched (ZCS) series resonant rectifier (SRR) is proposed. With the proposed control technique, the converter can operate in the safe region, and optimum rating devices can be used. By employing zero current switching operations for all switches, the series resonant rectifier can operate at high switching frequencies and high power levels.

Young Seok Jung; Jong Sun Ko; Gun Woo Moon; Myung Joong Youn

1995-01-01

6

Automatic load control for highly efficient microwave rectifiers  

Microsoft Academic Search

This paper presents an adaptive microwave rectifier at 2.45 GHz with automatic load control to improve the conversion efficiency. The conversion efficiency of a rectifier usually changes as the input power level changes, mainly due to the diode efficiency loss associated with built-in voltage or breakdown effect. Therefore, the conversion efficiency can achieve an optimal value only at a specific

Jiapin Guo; Haocheng Hong; Xinen Zhu

2012-01-01

7

Development of PI controller for battery charger using PFC rectifier  

Microsoft Academic Search

This paper illustrated simulation evaluations of a PI Controller for battery Charger employing Power Factor Correction (PFC) rectifier using MATLAB Simulink software packages and was compared with hardware prototype. The proposed system has been used single-phase incorporated with proportional-integral control technique to give appropriate compensation to resolve problems caused by the load such as current displacement, current harmonics and to

M. N. M. Hussain; M. F. M. Idris; I. Intan Rahayu; K. H. Mustafar; D. Nor Salwa; O. Nor Azlan; R. Rosfariza

2010-01-01

8

High Dinamic Control of a PWM Rectifier using Harmonic Elimination  

Microsoft Academic Search

In this paper the problem of current control in high power converters using low frequency, precalculated switching patterns is addressed. To overcome the problem of switching harmonics feeding through the current controllers a harmonic prediction and compensation method is devised. The good performance of the method is tested extensively through simulation of an three level PWM rectifier modulated with a

C. Silva; J. Oyarzun

2006-01-01

9

Upgrading Outdated Rectifier Control Systems - Needs and Challenges  

Microsoft Academic Search

Rectifier control systems supplied in the 1970's and 80's were based upon analog technology. These systems typically have failures which result in longer down times since components are either not available, are obsolete or need to be repaired. Tolerance degradation of these components contributes to problems such as loss of regulation accuracy or the malfunctioning gate firing circuits leading to

S. Tambe; P. Koester; E. Lambert

2006-01-01

10

Average current control of three-phase PWM boost rectifier  

Microsoft Academic Search

Average current control of three-phase PWM boost rectifiers with three linear current compensators and six-step PWM is a very attractive solution for its simplicity. The performance of the closed-loop control depends on the compensator design. This paper presents a modeling, analysis and design procedure for the average current control scheme. The current compensator design is verified experimentally on a high-frequency

Silva Hiti; Dusan Borojevic; Ravindra Ambatipudi; Richard Zhang; Yimin Jiang

1995-01-01

11

Sliding mode control for cascaded H-bridge boost rectifiers  

Microsoft Academic Search

The control of cascaded H-bridge boost rectifiers is a challenging task, due to the inherent coupling of the H-bridge modules. This property highlights the demand for a robust control technique, appropriate for this nonlinear and non-minimum phase system. This paper introduces an approach that combines a deeper understanding of the system's power flow with the well known robustness of the

A. X. Kaletsanos; I. S. Manolas; K. G. Pavlou; S. N. Manias

2010-01-01

12

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

NASA Astrophysics Data System (ADS)

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

Sheridan, David Charles

13

Design and Research on New Electrohydraulic Rectifying Control System of Hydraulic Formation Machines  

Microsoft Academic Search

The Rectifying Control System is a important system for the Hydraulic Formation Machines, and directly effects the accuracy of the construction. It will demonstrate the excellent performance of Rectifying accuracy of the system in this paper, by the development of New electro-hydraulic Rectifying Control System and the large work of experimental test. That was a new attempt for some structures

Huang Zizhai; Zhao Jingyi; Fang Xiangyang; Li Yang

2010-01-01

14

Sequential connection and phase control of a high-current rectifier optimized for copper electrowinning applications  

Microsoft Academic Search

This paper proposes an optimized sequential control technique for copper electrowinning high-current rectifiers. The converter comprises two series-connected six-pulse double-wye rectifiers, a step-down transformer, and a tuned input filter. The six-pulse rectifiers are fed from delta and polygon primary windings with different turns ratio and phase shifted by 5°. Under the proposed control scheme, one rectifier is kept at nominal

Eduardo P. Wiechmann; Rolando P. Burgos; Joachim Holtz

2000-01-01

15

Study of high power factor rectifiers based on one cycle control in aircraft electric power system  

Microsoft Academic Search

The object of this paper is to present further study of three-phase rectifiers based on one-cycle control in aircraft electric power system. The fundamental vector principle of one cycle control is introduced and analyzed briefly. The Simulated model of three-phase Rectifiers based on one-cycle control is build by software Saber. The 4 kW prototype of three-phase rectifiers based on the

Tao Lei; Xiao-Bin Zhang; Yan-Jun Dong; Jing-Hui Zhao; Hui Lin

2008-01-01

16

Inward Rectifier Potassium Channels Control Rotor Frequency in Ventricular Fibrillation  

PubMed Central

Summary Ventricular fibrillation (VF) is the most important cause of sudden cardiac death. While traditionally thought to result from random activation of the ventricles by multiple independent wavelets, recent evidence suggests that VF may be determined by the sustained activation of a relatively small number of reentrant sources. In addition, recent experimental data in various species as well as computer simulations have provided important clues about its ionic and molecular mechanisms, particularly in regards to the role of potassium currents in such mechanisms. The results strongly argue that the inward rectifier current, Ik1, is an important current during functional reentry because it mediates the electrotonic interactions between the unexcited core and its immediate surroundings. In addition, IK1 is a stabilizer of reentry due to its ability to shorten action potential duration and reducing conduction velocity near the center of rotation. Increased I K1 prevents wavefront-wavetail interactions and thus averts rotor destabilization and breakup. Other studies have shown that while the slow component of the delayed rectifier potassium current, IKs, does not significantly modify rotor frequency or stability, it plays a major role in post-repolarization refractoriness and wavebreak formation. Therefore, the interplay between IK1 and the rapid sodium inward current (INa) is a major factor in the control of cardiac excitability and therefore the stability and frequency of reentry while IKs is an important determinant of fibrillatory conduction.

Jalife, Jose

2009-01-01

17

Modeling and Decoupling Control of ICE APU with Uncontrolled Rectifier in Series Hybrid Vehicle  

Microsoft Academic Search

In series hybrid vehicle ICE (internal combustion engine), generator with rectifier and exciter are connected together as APU (Auxiliary Power Unit) to provide electricity for vehicle power system. The use of uncontrolled diode rectifier after AC synchronous generator can reduce system cost, but also makes the system difficult to control due to lacking of control variables. In order to achieve

Shuo Tian; Guijun Cao; Qiang Han; Jianqiu Li; Minggao Yang

2006-01-01

18

Discrete-time Model Following Control of Inverter with Rectifier Load  

NASA Astrophysics Data System (ADS)

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

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

19

A new synchronous reluctance generator AC\\/DC buck rectifier as a controllable power supply  

Microsoft Academic Search

This paper sets forth the use of a three-phase synchronous reluctance generator feeding a pulse-width modulation (PWM) based AC\\/DC buck rectifier to produce controllable AC and\\/or DC power. This is made possible by controlling both the modulation magnitude and phase angle of the rectifier. This generating scheme is targeted for application requirements for equipment on airplanes, ships or ground vehicles

Olorunfemi Ojo; Ishwar Bhat

1994-01-01

20

An integrated AC drive system using a controlled-current PWM rectifier\\/inverter link  

Microsoft Academic Search

Two identical three-phase, bipolar transistor, controlled-current, pulsewidth modulation (PWM) power modulators are integrated so that one functions as a rectifier and the other as an inverter in an AC drive system. The rectifier input currents maintain near-60-Hz sinusoidal waveforms with unity power factor. A leading power factor is also possible. The modulators do not depend on the availability of bidirectional

B. T. Ooi; JUAN W. DIXON; ASHOK B. KULKARNI; MASAHIRO NISHIMOTO

1988-01-01

21

Design and evaluation of a cellular rectifier system with distributed control  

Microsoft Academic Search

This paper presents the design and experimental evaluation of a six-cell 6 kW cellular (parallel) rectifier system which operates at nearly unity power factor. The cellular rectifier system implements both distributed load sharing and distributed ripple cancellation, eliminating the need for any centralized control. The implemented system mitigates some of the major drawbacks of its single-converter counterpart and achieves performance

David J. Perreault; John G. Kassakian

1999-01-01

22

A critical review of ohmic and rectifying contacts for silicon carbide  

Microsoft Academic Search

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

Lisa M. Porter; Robert F. Davis

1995-01-01

23

Development of a fuzzy logic controller for boost rectifier with active power factor correction  

Microsoft Academic Search

This paper presents the use of fuzzy logic to derive a practical control scheme for a boost rectifier with active power factor correction. The methodology integrates a fuzzy logic control technique in the feedback path and linear programming rule on controlling the duty cycle of the switch for shaping the input current waveform. The proposed approach avoids complexities associated with

Henry S. H. Chung; Eugene P. W. Tam; S. Y. R. Hui

1999-01-01

24

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

Microsoft Academic Search

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

Zhonghui Bing; Xiong Du; Jian Sun

2011-01-01

25

A Three-Phase Delta Switch Rectifier for More Electric Aircraft Applications Employing a Novel PWM Current Control Concept  

Microsoft Academic Search

In the course of the more electric aircraft program active three-phase rectifiers in the power range of 5 kW are required. A comparison with other rectifier topologies shows that the three-phase Delta-switch rectifier (comprising three Delta-connected bidirectional switches) is well suited for this application. The system is analyzed using space vector calculus and a novel PWM current controller concept is

M. Hartmann; J. Miniboeck; J. W. Kolar

2009-01-01

26

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

27

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

28

Robust dead-beat current control for PWM rectifiers and active filters  

Microsoft Academic Search

This paper analyzes the stability limitations of digital dead-beat current control applied to voltage-source three-phase converters used as pulsewidth modulation rectifiers and\\/or active filters. In these applications, the conventional control algorithm, as used in drive applications, is not sufficiently robust and stability problems may arise for the current control loop. The current loop is, indeed, particularly sensitive to any model

Luigi Malesani; Paolo Mattavelli; Simone Buso

1999-01-01

29

A new control algorithm for three-phase PWM buck rectifier with input displacement factor compensation  

Microsoft Academic Search

A new control algorithm for the three-phase buck rectifier with an input filter is developed. The algorithm employs a separate control loop for compensation of the input current displacement factor in steady-state, in addition to the standard output voltage regulation loop. The algorithm allows separate design of the input filter and of closed-loop output voltage control. The design procedure is

S. Hiti; V. Vlatkovic; D. Borojevic; F. C. Y. Lee

1994-01-01

30

Paralleled DSP-based soft switching-mode rectifiers with robust voltage regulation control  

Microsoft Academic Search

This paper presents the current sharing and robust voltage regulation controls for paralleled digital signal processor-based soft switching-mode rectifiers (SSMRs). First, the design and implementation of single-module SSMRs are made. In dealing with the current control loop design of each SSMR module, the small-signal model is derived and used to design the current-controlled pulse-width modulation (PWM) scheme. As to the

Sheng-Hua Li; Chang-Ming Liaw

2004-01-01

31

Design of Series Silicon-Controlled Rectifier Inverter.  

National Technical Information Service (NTIS)

There are two methods by which switches of similar devices can be used to generate AC. In a parallel inverter circuit, a constant current source is used and the switches are used to pass square waves of constant current. In a series inverter circuit, a co...

W. L. Hendren

1965-01-01

32

SSMFs fuzzy logic control and neural network based alpha compensation of phase controlled rectifier fed DC drives  

Microsoft Academic Search

In this paper, fuzzy logic and neural network concepts are applied to DC drive system. A systematic approach to construct membership functions of FLC using shrinking span membership functions (SSMFs), is adopted here. This paper proposes a SSMFs fuzzy logic controller for current and speed control loops of DC drive systems. Neural network is employed to linearize the rectifier transfer

S. Baskar; P. Subbaraj; N. M. P. Kumar

1998-01-01

33

Three-phase unity-power-factor star-connected switch (VIENNA) rectifier with unified constant-frequency integration control  

Microsoft Academic Search

A unified constant-frequency integration (UCI) controller for a three-phase star-connected switch three-level rectifier (VIENNA) with unity-power-factor-correction is proposed. One of advantages of this rectifier is that the switch voltage stress is one half of the total output voltage. The proposed control approach is based on one-cycle control and features great simplicity and reliability: all three phases will be power factor

Chongming Qiao; Keyue Ma Smedley

2003-01-01

34

A new strategy for control of cascaded H-bridge rectifiers with uneqaul loads  

Microsoft Academic Search

In this paper, a new control strategy is applied to a cascaded H-bridge (CHB) rectifier in order to regulate dc bus voltages and to balance them, even if the attached loads consume various amounts of power. The input current is also programmed to be sinusoidal and in-phase with the input voltage. With the maximum switching frequency of 1 kHz, the

Ali Keshavarzian; Hossein Iman-Eini

2011-01-01

35

Virtual-flux-based direct power control of three-phase PWM rectifiers  

Microsoft Academic Search

In this paper, direct power control (DPC) of three-phase pulsewidth-modulated rectifiers without line voltage sensors is presented. The new system is based on virtual flux (VF) estimation. Theoretical principles of this method are discussed. The steady-state and dynamic behavior of VF-DPC are presented that illustrate the operation and performance of the proposed system compared to a conventional DPC method. Both

Mariusz Malinowski; Marian P. Kazmierkowski; Steffan Hansen; Frede Blaabjerg; G. D. Marques

2001-01-01

36

A comparison of the reliability of a matrix converter and a controlled rectifier-inverter  

Microsoft Academic Search

This paper compares the calculated reliability of a matrix converter with a controlled rectifier\\/inverter topology for an aerospace motor drive application. These topologies are functionally equivalent in terms of input power quality and regenerative capabilities. The military handbook MIL-HDBK-217F guidelines have been used to predict reliability. Although the matrix converter has a higher number of semiconductor switches, these switches are

P. W. Wheeler; J. C. Clare; L. de Lillo; K. J. Bradley; M. Aten; C. Whitley; G. Towers

2005-01-01

37

Using 12 MeV electron beams to develop silicon P+NN+ high frequency rectifying diodes  

NASA Astrophysics Data System (ADS)

Twelve MeV electron beams were used to irradiate common P+NN+ diodes (1 A and 1 kV) in order to transfer them into high frequency rectifying ones. Some interesting results have been obtained. It seems that this method is superior to the traditional gold-doping technique in controlling precisely the lives of the minority carriers. Compared with the later electron beam irradiation made the reverse recovery time (trr) and FWD-voltage (VF) of the diodes better consistent and repeatable. The high temperature performance was also obviously improved. The qualified rate of diodes was enhanced by more than 30%.

Desheng, H.; Qiji, L.; Yi, S.; Zheng, Z.

2000-12-01

38

A new control algorithm for three-phase PWM buck rectifier with input displacement factor compensation  

SciTech Connect

A new control algorithm for the three-phase buck rectifier with an input filter is developed. The algorithm employs a separate control loop for compensation of the input current displacement factor in steady-state, in addition to the standard output voltage regulation loop. The algorithm allows separate design of the input filter and of closed-loop output voltage control. The design procedure is explained and illustrated with an example. The algorithm is verified experimentally on a 1 kW, 100 kHz, three-phase isolated buck converter.

Hiti, S.; Vlatkovic, V.; Borojevic, D.; Lee, F.C.Y. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Bradley Dept. of Electrical Engineering)

1994-03-01

39

High-performance digital triggering system for phase-controlled rectifiers  

SciTech Connect

The larger power supplies used to power accelerator magnets are most commonly polyphase rectifiers using phase control. While this method is capable of handling impressive amounts of power, it suffers from one serious disadvantage, namely that of subharmonic ripple. Since the stability of the stored beam depends to a considerable extent on the regulation of the current in the bending magnets, subharmonic ripple, especially that of low frequency, can have a detrimental effect. At the NSLS, we have constructed a 12-pulse, phase control system using digital signal processing techniques that essentially eliminates subharmonic ripple.

Olsen, R.E.

1983-01-01

40

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.

Lee, Hyung-Min; Ghovanloo, Maysam

2011-01-01

41

Analysis and design of direct power control (DPC) for a three phase synchronous rectifier via output regulation subspaces  

Microsoft Academic Search

In this paper, the authors present a controller that directly regulates the active and instantaneous reactive power in a synchronous three-phase boost-type rectifier. The controller ensures a good regulation of the output voltage, and guarantees the power factor close to one. The controller builds upon the ideas of the well known direct torque control (DTC) for induction motors. In their

Gerardo Escobar; Aleksandar M. Stankovic; Juan M. Carrasco; Eduardo Galván; Romeo Ortega

2003-01-01

42

Novel estimator of distorted and unbalanced electromotive force of the grid for control system of PWM rectifier with active filtering  

Microsoft Academic Search

Control of PWM rectifier with active filtering is realized by fast and precise shaping of its AC currents. In the paper the control system with predictive algorithms of both set currents calculation and currents control is proposed. These algorithms provide very high accuracy and dynamics of AC currents shaping which is limited only by parameters of the power circuits. In

Daniel Wojciechowski

2005-01-01

43

Analytic and Iterative Algorithms for Online Estimation of Coupling Inductance in Direct Power Control of Three-Phase Active Rectifiers  

Microsoft Academic Search

One of the best known control methods for three- phase active rectifiers is the so-called direct power control (DPC). The control algorithm of the DPC is primarily based on the reg- ulation of instantaneous active and reactive power. Because the DPC method can operate without any grid voltage sensors, instan- taneous power and grid phase voltages must be estimated. The

Joaquín González Norniella; José M. Cano; Gonzalo Alonso Orcajo; Carlos H. Rojas Garcia; Joaquín Francisco Pedrayes; Manés F. Cabanas; Manuel G. Melero

2011-01-01

44

A novel control method for input output harmonic elimination of the PWM boost type rectifier under unbalanced operating conditions  

Microsoft Academic Search

This paper presents a new control strategy to improve the performance of the PWM boost type rectifier when operating under an unbalanced supply. An analytical solution for harmonic elimination under unbalanced input voltages is obtained resulting in a smooth (constant) power flow from AC to DC side in spite of the unbalanced voltage condition. Based on the analysis of the

Ana Vladan Stankovic; Thomas A. Lipo

2001-01-01

45

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

46

Comparison of not synchronized sawtooth carrier and synchronized triangular carrier phase current control for the VIENNA rectifier I  

Microsoft Academic Search

Integrated control circuits being available for the input current control of single-phase power factor correctors are frequently applied also for realizing a simple current control for each phase of a three-phase PWM rectifier system. There, the input currents are controlled independently although the three phases are mutually coupled, i.e., the sum of the phase currents is forced to zero for

Uwe DROFENIK; Johann W. KOLAR

1999-01-01

47

Automatic Distributed Load Temperature Control Strategies for a Rectified Continuous Flow Loop Interfaced with a Pulse Tube Cryocooler  

NASA Astrophysics Data System (ADS)

Distributed thermal loads are frequently encountered in large deployable structures used in space applications such as optical mirrors and focal plane electronics. An innovative mechanism for providing distributed cooling is an oscillatory pulse-tube cryocooler that is integrated with a fluid rectification system consisting of check-valves and buffer volumes in order to extract a small amount of continuous flow. This continuous flow allows relatively large loads to be accepted over a long distance. An additional advantage of the rectified system is the ability to provide rapid and precise temperature control via modulation of the flow rate in the flow loop. This paper presents an experimental demonstration of this temperature control method. A rectified interface is integrated with a thermal load and subjected to various thermal disturbances. Temperature regulation is enabled using temperature feedback control of a valve placed in the distribution loop. The control parameters are selected to meet temperature regulation specifications, including maximum temperature deviation and settling time in response to a step change in distributed load. The measured controlled transient behaviors to step and sinusoidal distributed load variations are presented. The predicted and measured behaviors are compared in order to validate the thermal model of the rectifying interface system.

Skye, H. M.; Nellis, G. F.; Klein, S. A.

2008-03-01

48

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

PubMed

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

Atherton, D L; Davies, R

1979-10-01

49

A Modular Strategy for Control and Voltage Balancing of Cascaded H-Bridge Rectifiers  

Microsoft Academic Search

In this paper, a new strategy for voltage balancing of distinct dc buses in cascaded H-bridge rectifiers is presented. This method ensures that the dc bus capacitor voltages converge to the reference value, even when the loads attached to them are extracting different amounts of power. The proposed method can be used for an arbitrary number of series H-bridges, different

Hossein Iman-Eini; Jean-Luc Schanen; Shahrokh Farhangi; James Roudet

2008-01-01

50

Controlled growth of silicon nanowires  

Microsoft Academic Search

Using the solid-liquid-solid method, silicon nanowires were grown by annealing the gold-coated silicon substrates under the nitrogen flow. In this method, gold diffused into the silicon substrate upon heating and AuSi alloy formed at their interface. This alloy was melted when temperature increases above their eutectic point and percentage of Si presence in the mixture increased as heating continues. Rapid

Y. Y. Wong; M. Yahaya; M. Mat Salleh; B. Yeop Majlis

2005-01-01

51

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.

2012-10-24

52

Advanced control of a boost AC-DC PWM rectifier for variable-speed induction generator  

Microsoft Academic Search

This paper describes simple control structures for vector controlled stand-alone induction generator (IG) used to operate under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with newly designed phase locked loop circuit. The required reactive

Tarek Ahmed; Mutsuo Nakaoka; Toshihiko Tanaka; Katsumi Nishida

2006-01-01

53

A four level rectifier-inverter system for drive applications  

Microsoft Academic Search

Multilevel converter technology has been receiving increased attention, especially for high power applications. In particular, three level drive systems have been extensively reported. In this paper, a four level rectifier-inverter system is investigated for drive applications. A dynamic control algorithm is described which balances the voltages on a 4 level rectifier-inverter drive system primarily from the rectifier. The proposed control

Gautam Sinha; T.A. Lipo

1996-01-01

54

Circulant Synthesis of Central Pattern Generators With Application to Control of Rectifier Systems  

Microsoft Academic Search

While regulations around an equilibrium point or a reference trajectory have been the focus of recent feedback control theories, generation of autonomous oscillations with a specific pattern plays a crucial role in important control applications such as robotics. The central pattern generator (CPG) is the fundamental neuronal mechanism underlying rhythmic movements of animals, and may provide a new paradigm for

Zhiyong Chen; Tetsuya Iwasaki

2008-01-01

55

GGSCRs: GGNMOS Triggered silicon controlled rectifiers for ESD protection in deep sub-micron CMOS processes  

Microsoft Academic Search

In this paper, design aspects, operation, protection capability and applications of SCRs in deep sub-micron CMOS are addressed. A novel Grounded-Gate NMOS Triggered SCR device (GGSCR) is introduced and compared to the LVTSCR. Experimental verification, including endurance testing, demonstrates that GGSCRs can fulfill all ESD protection requirements for todays IC applications in different 0.25 um, 0.18 um and 0.13 um

Christian C. Russ; Markus P. J. Mergens; Koen G. Verhaege; John Armer; Phillip C. Jozwiak; Girija Kolluri; Leslie R. Avery

2001-01-01

56

Space Vector Modulation Control of an AC–DC–AC Converter With a Front-End Diode Rectifier and Reduced DC-link Capacitor  

Microsoft Academic Search

In this paper, the control of an ac-dc-ac converter with a front-end diode rectifier and reduced dc-link capacitor based on the space vector modulation strategy is investigated. The modulation index is time-varying and determined by the instantaneous value of the dc voltage measured by a voltage sensor. Using a small bipolar capacitor, instead of a large electrolytic capacitor on the

Xiyou Chen; Mehrdad Kazerani

2006-01-01

57

A ROBUST PASSIVE POWER-BASED CONTROL STRATEGY FOR THREE-PHASE VOLTAGE-SOURCE RECTIFIERS  

Microsoft Academic Search

In this paper, robustness of the damping injection schemes for passivity based control (PBC) of the three-phase AC\\/DC voltage-source (Boost type) rectier is studied. The idea is to extend the tuning strategy for PBC that is presented in (Jeltsema and Scherpen, 2004) for DC\\/DC converters to three-phase AC\\/DC rectiers. In the DC\\/DC converter case this tuning strategy leads to a

Dimitri Jeltsema; Jacquelien M. A. Scherpen; Elodie Hageman; Ecole Centrale de Nantes

58

Controlled Adhesion of Silicone Elastomer Surfaces  

NASA Astrophysics Data System (ADS)

Opportunities exist for controllably enhancing the adhesion of silicone surfaces, ranging from modest enhancement of release force levels of pressure-sensitive adhesive (PSA) release liners by incorporation of adhesion promoters known as high release additives (HRA), to permanent bonding of silicone elastomers using surface modification techniques such as plasma or corona treatment. Although only a part of the complex interaction of factors contributing to adhesion, surface properties such as wettability are a critical component in the understanding and control of release and adhesion phenomena. Surface characterization studies of low-surface-energy silicones before and after various adhesion modification strategies are reviewed. The silicones include polydimethylsiloxane (PDMS) and fluorosiloxane elastomers and coatings. Techniques used include contact angle, the Johnson, Kendall and Roberts (JKR) contact mechanics approach, scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Topics addressed are: use of HRA in PDMS release liners, the interaction of PDMS PSAs with polytetrafluoroethylene (PTFE), and the effect of plasma treatment on PDMS and fluorosiloxane surfaces.

Owen, Michael

2000-03-01

59

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

60

Sensorless Field Oriented Control utilizing a Sliding Mode Observer for control of an actively-rectified permanent magnet synchronous generator  

Microsoft Academic Search

The study of sensorless control for permanent magnet synchronous machines (PMSM) has progressed rapidly over the past decade. This is contributed to the increased reliability and reduced cost obtained by removal of the traditional mechanical feedback devices that were needed to accurately report rotor position in applications requiring a Field Oriented Control (FOC) scheme. In these type applications, accurate electrical

Justin Owen; Jeff Strouse; Michael J. Marcel

2011-01-01

61

Controlling the Thermal Decomposition of Silicon Carbide into Graphene  

Microsoft Academic Search

The quality of epitaxial graphene films grown by thermal decomposition of silicon carbide depends on experimental control of the net silicon desorption rate. Such control has been previously demonstrated by three techniques: tight confinement within an induction furnace, growth in 1-atm Ar buffer gas, or introduction of a silane overpressure. Our goal is to study the physics of these methods.

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

2011-01-01

62

Speed and Voltage Control of Electrical Machines with the Aid of Thyrystors (Transistors) (Regulacja Predkosci I Napiecia W Maszynach Electroycznych Za Pomocq Tyrystorow).  

National Technical Information Service (NTIS)

The paper discusses systems for the stabilization and control of voltage, current, rate, and torque of electrical motors which use silicon controlled rectifiers (SCR). Detailed discussions cover the following topics: the output characteristics of stabiliz...

W. Paszek J. Kubek J. Hickiewicz M. Zywiec

1967-01-01

63

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.

2008-07-02

64

Rectified Alternating-Current Converter.  

National Technical Information Service (NTIS)

A half-wave and a voltage multiplying rectifier circuit is provided in which the full smoothing and regulating advantages of a filter inductor are realized. This is accomplished in a half-wave rectifier circuit by applying the rectified output of an alter...

G. F. Montgomery

1965-01-01

65

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

NASA Astrophysics Data System (ADS)

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

Hirayama, Tadashi; Higuchi, Tsuyoshi

66

Reversible fluctuation rectifier.  

PubMed

The analysis of a Feynman's ratchet system [J. M. R. Parrondo and P. Español, Am. J. Phys. 64, 1125 (1996)] and of its electrical counterpart, a diode engine [I. M. Sokolov, Europhys. Lett. 44, 278 (1998)] has shown that "fluctuation rectifiers" consisting of a nonlinear element (ratchet, diode) and a linear element (vane, resistor) kept at different temperatures always show efficiency smaller than the Carnot value, thus indicating the irreversible mode of operation. We show that this irreversibility is not intrinsic for a system in simultaneous contact with two heat baths at different temperatures and that a fluctuation rectifier can work reversibly. This is illustrated by a model with two diodes switched in opposite directions, where the Carnot efficiency is achieved when backward resistivity of the diodes tends to infinity. PMID:11970361

Sokolov, I M

1999-10-01

67

Reversible fluctuation rectifier  

NASA Astrophysics Data System (ADS)

The analysis of a Feynman's ratchet system [J. M. R. Parrondo and P. Español, Am. J. Phys. 64, 1125 (1996)] and of its electrical counterpart, a diode engine [I. M. Sokolov, Europhys. Lett. 44, 278 (1998)] has shown that ``fluctuation rectifiers'' consisting of a nonlinear element (ratchet, diode) and a linear element (vane, resistor) kept at different temperatures always show efficiency smaller than the Carnot value, thus indicating the irreversible mode of operation. We show that this irreversibility is not intrinsic for a system in simultaneous contact with two heat baths at different temperatures and that a fluctuation rectifier can work reversibly. This is illustrated by a model with two diodes switched in opposite directions, where the Carnot efficiency is achieved when backward resistivity of the diodes tends to infinity.

Sokolov, I. M.

1999-10-01

68

Integrated Quantum Dot Schottky Diodes for RECTENNA (Rectifying Antenna)  

Microsoft Academic Search

In this paper we will present our latest research results of integrated quantum dot Schottky diodes and integrated silicon antenna for RF applications. Both, the quantum dot Schottky diodes and the antenna are integrated on Si substrates forming a simple mm-wave detection system, the rectifying antenna (RECTENNA). Within this work a specific antenna design, 1-dimensional array (single line antenna), will

H. Xu; A. Karmous; M. Morschbach; O. Kirfel; S. Spiessberger; E. Kasper

2009-01-01

69

Location control of giant silicon grains using organic lenses  

NASA Astrophysics Data System (ADS)

We studied the location control of a giant grain of polycrystalline silicon produced by Ni-mediated crystallization of amorphous silicon (a-Si) using a cap layer. An organic lens made of acryl was used for the focusing of light for the seed formation and subsequent crystallization. A single grain 62 ?m in diameter was made using an 80-?m-square SiNx cap layer on the a-Si. The position of a thin-film transistor (TFT) on a grain can be controlled, so that a single grain TFT can be fabricated at a predetermined position without use of the laser annealing technique.

Oh, Jae Hwan; Kim, Eun Hyun; Kim, Sang Kyu; Cheon, Jun Hyuk; Son, Yong Duck; Jang, Jin

2005-12-01

70

G-protein-gated inwardly rectifying K+ channel 4 (GIRK4) immunoreactivity in chemically defined neurons of the hypothalamic arcuate nucleus that control body weight.  

PubMed

G-protein-gated inwardly rectifying K(+) channels (GIRKs; also called Kir3) are a family of K(+) channels, which are activated (opened) via a signal transduction cascade starting with ligand-stimulated G-protein-coupled receptors (GPCRs). Four GIRK genes have been identified (GIRK1-4). GIRK4 (Kir3.4) has a role in regulating energy homeostasis, since mice with a targeted mutation in the GIRK4 gene exhibit a predisposition to late-onset obesity. GIRK4 mRNA is expressed in hypothalamic regions that harbor neurons involved in the regulation of food intake and body weight. Using goat and rabbit antisera to the GIRK4 protein, the cellular localization and transmitter content of GIRK4-immunoreactive neurons was determined in the hypothalamic arcuate nucleus, a region that contains neurons which are accessible to circulating hormones and is intimately associated with the control of body weight. GIRK4-immunoreactive large cell bodies were demonstrated in the ventrolateral part of the arcuate nucleus, with smaller neuronal cell bodies in the ventromedial part of the nucleus. Double-labeling showed presence of GIRK4 immunoreactivity in large neurons of the ventrolateral arcuate nucleus containing the peptides ?-melanocyte-stimulating hormone (?-MSH), a marker for pro-opiomelanocortin (POMC) neurons, and cocaine- and amphetamine-regulated transcript (CART). GIRK4 immunoreactivity was also seen in neurons of the ventromedial part of the arcuate nucleus containing agouti-regulated peptide (AgRP) and neuropeptide Y (NPY). The results suggest that the GIRK4 channel protein plays a role in regulating membrane excitability in chemically defined neurons of the arcuate nucleus that control body weight. PMID:22465809

Kloukina, Vaia; Herzer, Silke; Karlsson, Niklas; Perez, Monica; Daraio, Teresa; Meister, Björn

2012-03-23

71

On-chip silicon photonic wavelength control of laser source  

NASA Astrophysics Data System (ADS)

Tunable silicon microring filters are used to demonstrate CMOS-compatible on-chip wavelength control of Er+ doped fiber-lasers. The filter uses a 10 ?m-diameter microring resonator based on single-mode silicon-on-insulator (SOI) strip waveguides operating around the telecom range of 1.55 ?m. A piece of Er+ doped fiber (EDF) serves as the gain media which is pumped by a 980 nm laser diode. An on-chip Ni-Cr micro-heater consuming up to 38 mW is capable of tuning the Si microring filter by 2.3 nm with a lasing linewidths narrower than 0.02 nm. This approach enables arbitrary multiple wavelength generation on a silicon chip. Possible applications include on-chip and chip-to-chip densewavelength division multiplexed communications, telecommunications and optical sensor interrogation.

Wang, Xuan; Liu, Tao; Almeida, Vilson R.; Panepucci, Roberto R.

2009-02-01

72

Optically controlled photonic crystal nanocavity in silicon  

NASA Astrophysics Data System (ADS)

We present experimental demonstration of fast all-optical switching in a one-dimensional photonic crystal nanocavity embedded in a Silicon waveguide. The transmission of the device is tuned by injecting free carriers into the nanocavity region using an optical pump beam. By strongly confining light in the photonic crystal nanocavity the sensitivity of light to small refractive index changes is enhanced. The small cavity volume (~0.1 ?m3) and unpassivated sidewalls enable ultra-fast switching speeds with low pulse energies. Using a pulse energy of only 60pJ, a refractive index change of approximately 10-2 is obtained. This small index change, due to the high confinement nature of the cavity structure, leads to a strong change in transmission spectrum. Consequently, the resonance is shifted up to its full-width-at half-maximum (~7.5nm), and the transmission of the device is modulated by 71% with a time response of less than 1.5 ns. Such a device could open the door to the large-scale integration of ultra-fast modulators and switches.

Preble, Stefan F.; Almeida, Vilson R.; Lipson, Michal

2004-10-01

73

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.

2012-12-14

74

Robot Control: From Silicon Circuitry to Cells  

Microsoft Academic Search

Life-like adaptive behaviour is so far an illusive goal in robot control. A capability to act successfully in a complex, ambiguous, and harsh environment would vastly increase the application domain of robotic devices. Established methods for robot control run up against a complexity barrier, yet living organisms amply demonstrate that this barrier is not a fundamental limitation. To gain an

Soichiro Tsuda; Klaus-peter Zauner; Yukio-pegio Gunji

2006-01-01

75

Controllable molecular modulation of conductivity in silicon-based devices.  

PubMed

The electronic properties of silicon, such as the conductivity, are largely dependent on the density of the mobile charge carriers, which can be tuned by gating and impurity doping. When the device size scales down to the nanoscale, routine doping becomes problematic due to inhomogeneities. Here we report that a molecular monolayer, covalently grafted atop a silicon channel, can play a role similar to gating and impurity doping. Charge transfer occurs between the silicon and the molecules upon grafting, which can influence the surface band bending, and makes the molecules act as donors or acceptors. The partly charged end-groups of the grafted molecular layer may act as a top gate. The doping- and gating-like effects together lead to the observed controllable modulation of conductivity in pseudometal-oxide-semiconductor field-effect transistors (pseudo-MOSFETs). The molecular effects can even penetrate through a 4.92-mum thick silicon layer. Our results offer a paradigm for controlling electronic characteristics in nanodevices at the future diminutive technology nodes. PMID:19569647

He, Tao; Corley, David A; Lu, Meng; Di Spigna, Neil Halen; He, Jianli; Nackashi, David P; Franzon, Paul D; Tour, James M

2009-07-29

76

Brownian trail rectified  

SciTech Connect

The experiments described here indicate when one of Nature's best fractals -- the Brownian trail -- becomes nonfractal. In most ambient fluids, the trail of a Brownian particle is self-similar over many decades of length. For example, the trail of a submicron particle suspended in an ordinary liquid, recorded at equal time intervals, exhibits apparently discontinuous changes in velocity from macroscopic lengths down to molecular lengths: the trail is a random walk with no velocity memory'' from one step to the next. In ideal Brownian motion, the kinks in the trail persist to infinitesimal time intervals, i.e., it is a curve without tangents. Even in real Brownian motion in a liquid, the time interval must be shortened to {approximately}10{sup {minus}8}s before the velocity appears continuous. In sufficiently rarefied environments, this time resolution at which a Brownian trail is rectified from a curve without tangents to a smoothly varying trajectory is greatly lengthened, making it possible to study the kinetic regime by dynamic light scattering. Our recent experiments with particles in a plasma have demonstrated this capability. In this regime, the particle velocity persists over a finite step length'' allowing an analogy to an ideal gas with Maxwell-Boltzmann velocities; the particle mass could be obtained from equipartition. The crossover from ballistic flight to hydrodynamic diffusion was also seen. 8 refs., 1 fig.

Hurd, A.J.; Ho, P.

1989-01-01

77

VIENNA rectifier II-a novel single-stage high-frequency isolated three-phase PWM rectifier system  

Microsoft Academic Search

Based on an analysis of basic realization possibilities, the structure of the power circuit of a new single-stage three-phase boost-type pulsewidth modulated (PWM) rectifier system (VIENNA Rectifier II) is developed. This system has continuous sinusoidal time behavior of the input currents and high-frequency isolation of the output voltage, which is controlled in a highly dynamic manner. As compared to a

Johann W. Kolar; Uwe Drofenik; Franz C. Zach

1999-01-01

78

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

79

Sputtered tin silicon oxide films for durable solar control coatings  

Microsoft Academic Search

The optical, mechanical, and chemical properties of solar control coatings with a transparent tin silicon oxide (TSO) film were investigated. The TSO films were formed by reactive dc sputtering from alloy targets with the compositions of 90Sn–10Si, 80Sn–20Si, and 50Sn–50Si (at.%). Hereafter, the 50TSO film denotes the oxide film prepared from the 50Sn-50Si target. Triple layer (50TSO\\/TiNx\\/50TSO\\/glass) and double layer

E. Ando; S. Suzuki; J. Shimizu; Y. Hayashi

1999-01-01

80

A fast on-line neural-network training algorithm for a rectifier regulator  

Microsoft Academic Search

This paper addresses the problem of deadbeat control in fully controlled high-power factor rectifiers. Improved deadbeat control can be achieved through the use of neural network-based predictors for the input current reference to the rectifier. In this application, online training is absolutely required. In order to achieve sufficiently fast online training, a new random search algorithm is presented and evaluated.

Farrukh Kamran; Ronald G. Harley; Bruce Burton; Thomas G. Habetler; Martin A. Brooke

1998-01-01

81

Controlled thinning and surface smoothening of silicon nanopillars.  

PubMed

A convenient method has been developed to thin electron beam fabricated silicon nanopillars under controlled surface manipulation by transforming the surface of the pillars to an oxide shell layer followed by the growth of sacrificial ammonium silicon fluoride coating. The results show the formation of an oxide shell and a silicon core without significantly changing the original length and shape of the pillars. The oxide shell layer thickness can be controlled from a few nanometers up to a few hundred nanometers. While downsizing in diameter, smooth Si pillar surfaces of less than 10 nm roughness within 2 microm were produced after exposure to vapors of HF and HNO3 mixture as evidenced by transmission electron microscopy (TEM) analysis. The attempt to expose for long durations leads to the growth of a thick oxide whose strain effect on pillars can be assessed by coupled LO-TO vibrational modes of Si-O bonds. Photoluminescence (PL) of the pillar structures which have been downsized exhibits visible and infrared emissions, which are attributable to microscopic pillars and to the confinement of excited carriers in the Si core, respectively. The formation of smooth core-shell structures while reducing the diameter of the Si pillars has a potential in fabricating nanoscale electronic devices and functional components. PMID:19801781

Kalem, S; Werner, P; Nilsson, B; Talalaev, V G; Hagberg, M; Arthursson, O; Södervall, U

2009-10-05

82

A new ZVS-PWM active-clamping high power factor rectifier: analysis, design, and experimentation  

Microsoft Academic Search

In this paper a new single-phase rectifier is introduced, which features high power factor, regulation by conventional PWM technique, ZVS commutation and clamping action in both switches, and instantaneous average line current control. This rectifier consists of a front-end full-bridge diode rectifier followed by a ZVS-PWM, buck-boost active-clamping, boost converter. Experimental results are presented, taken from a laboratory prototype rated

Cliudio Manoel da Cunha Duarte; Ivo Barbi

1998-01-01

83

Series regulated rectifier circuit for a battery charging system  

SciTech Connect

A conventional on-off voltage regulator operates a set of power mosfet switches interposed between the grounded terminal of the battery and each of the diodes of a bridge rectifier leading to that terminal. Each such switch is controlled through an individual circuit responsive to the regulator output and including an opto-electronic device controlling a thryistor which, in addition to being connected to control the mosfet switch, also has a connection through a resistor and a diode to the other side of the rectifier diode switched by the mosfet. The circuit greatly simplifies voltage regulation of a battery charging system using an alternator with a permanent magnet rotor.

Kurz, W.; Munz, U.

1983-05-03

84

Low Voltage Slow Controls for the Silicon Vertex Tracker  

NASA Astrophysics Data System (ADS)

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

Hammerton, Kalee

2012-10-01

85

Control and data acquisition electronics for the CDF Silicon Vertex Detector  

SciTech Connect

A control and data acquisition system has been designed for the CDF Silicon Vertex Detector (SVX) at Fermilab. The system controls the operation of the SVX Rev D integrated circuit (SVX IC) that is used to instrument a 46,000 microstrip silicon detector. The system consists of a Fastbus Sequencer, a Crate Controller and Digitizer modules. 11 refs., 6 figs., 3 tabs.

Turner, K.J.; Nelson, C.A.; Shaw, T.M.; Wesson, T.R.

1991-11-01

86

D(1) dopaminergic control of G protein-dependent inward rectifier K(+) (GIRK)-like channel current in pyramidal neurons of the medial prefrontal cortex.  

PubMed

Pyramidal neurons of the medial prefrontal cortex (mPFC) exhibit dopamine-dependent prolonged depolarization, which may lead to persistent activity. Persistent activation of prefrontal cortex neurons has been proposed to underlie the working memory process. The purpose of our study was to test the hypothesis that activation of D(1) dopamine receptors leads to inhibition of G protein-dependent inward rectifier K(+) (GIRK) channels, thereby supporting the prolonged depolarization of mPFC pyramidal neurons. Experiments were performed on 3-week-old rats. GIRK-like channel currents recorded from pyramidal neurons showed the following properties at -75 mV: open probability (NPo), 2.5+/-0.3 x 10(-3); mean open time, 0.53+/-0.05 ms; and conductance, 29.9+/-1.6 pS (n=60). The channel currents were strongly inward-rectified. GIRK channel currents were reversibly inhibited by the D(1) agonists SKF 38393 (10 microM) and SKF 81297 (10 microM). This inhibition was abolished by prior application of a dopamine receptor antagonist and by application of the membrane-permeable protein kinase C inhibitors chelerythrine chloride (3 microM) and calphostin C (10 microM). It was also found that the application of D(1) dopamine receptor agonists or GIRK channel inhibitors evoked depolarization of mPFC pyramidal neurons in rats. Moreover, prior application of a GIRK channel blocker eliminated the depolarizing effect of D(1) agonists. We conclude that activation of D(1) dopamine receptors may lead to inhibition of GIRK channel currents that may, in turn, lead to the prolonged depolarization of mPFC pyramidal neurons in juvenile rats. PMID:18571868

Witkowski, G; Szulczyk, B; Rola, R; Szulczyk, P

2008-06-19

87

A High-Performance Control and Power Supply for Thermoelectric Heat-Pumping Air-Conditioning Systems  

Microsoft Academic Search

The control and power supply described is completely static, automatically reversible, and has proportional output with rate compensation. SCR's(silicon-controlled rectifiers), transistors, diodes, thermistors, and magnetic cores are used to perform the control functions. A silent, accurate, and compact air-conditioning system can be achieved when this control and power supply is used with a thermoelectric heat pump.

A. A. Beck

1964-01-01

88

Controlled skeletal progenitor cell migration on nanostructured porous silicon/silicon micropatterns  

NASA Astrophysics Data System (ADS)

In this work nanostructured porous silicon (nanoPS) was used for the fabrication of surface micropatterns aiming at controlling cell adhesion and migration. In particular, surface patterns of nanoPS and Si were engineered by high-energy ion-beam irradiation and subsequent anodization. It was found that human skeletal progenitor cells are sensitive to oneand two-dimensional patterns and that focal adhesion is inhibited on nanoPS areas. In spite of this anti-fouling characteristics, studies on patterns with reduced Si areas show that cells conform to nanoPS pathways favoring migration through cell protrusion, body translocation and tail retraction from two parallel Si traction rails. Moreover, migration can be blocked and cells tend to arrange when grid patterns with the appropriate dimensions are fabricated. The experimental results confirm that progenitor cells are able to exploit nanoPS anti-fouling designs by adapting to it for migration purposes.

Torres-Costa, V.; Sánchez-Vaquero, V.; Muñoz-Noval, Á.; González-Méndez, L.; Punzón-Quijorna, E.; Gallach-Pérez, D.; Manso-Silván, M.; Martínez-Muñoz, G.; Climent-Font, A.; García-Ruiz, J. P.; Martín-Palma, R. J.

2011-09-01

89

Single-Switch Single-Phase Voltage-Quadrupler Rectifier  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier using a single active power device is presented. This is based on the combination of a half-bridge rectifier and the circuits operated in the switching states for pumping action to pump twice the peak supply voltage onto each of the output capacitors. The experimental prototype employing an insulated-gate bipolar transistor and a controller for output voltage regulation is implemented to investigate the operation. The experimental results confirm that the input current can almost be waveshaped sinusoidally with a near-unity power factor under the output voltage quadruplication.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Hirata, Yuki

90

Electronic measurement and control of spin transport in silicon  

NASA Astrophysics Data System (ADS)

The spin lifetime and diffusion length of electrons are transport parameters that define the scale of coherence in spintronic devices and circuits. As these parameters are many orders of magnitude larger in semiconductors than in metals, semiconductors could be the most suitable for spintronics. So far, spin transport has only been measured in direct-bandgap semiconductors or in combination with magnetic semiconductors, excluding a wide range of non-magnetic semiconductors with indirect bandgaps. Most notable in this group is silicon, Si, which (in addition to its market entrenchment in electronics) has long been predicted a superior semiconductor for spintronics with enhanced lifetime and transport length due to low spin-orbit scattering and lattice inversion symmetry. Despite this promise, a demonstration of coherent spin transport in Si has remained elusive, because most experiments focused on magnetoresistive devices; these methods fail because of a fundamental impedance mismatch between ferromagnetic metal and semiconductor, and measurements are obscured by other magnetoelectronic effects. Here we demonstrate conduction-band spin transport across 10?m undoped Si in a device that operates by spin-dependent ballistic hot-electron filtering through ferromagnetic thin films for both spin injection and spin detection. As it is not based on magnetoresistance, the hot-electron spin injection and spin detection avoids impedance mismatch issues and prevents interference from parasitic effects. The clean collector current shows independent magnetic and electrical control of spin precession, and thus confirms spin coherent drift in the conduction band of silicon.

Appelbaum, Ian; Huang, Biqin; Monsma, Douwe J.

2007-05-01

91

A gallium arsenide power rectifier  

Microsoft Academic Search

In this paper we will describe the fabrication of a gallium arsenide rectifier with a 10 ampere forward current capability, and reverse breakdowns of 40-100 volts. These units are fabricated by a manganese diffusion into gallium arsenide having a prediffusion carrier concentration of about3 times 10^{16}\\/cm3. The diffusion techniques and evaluation will be described. Problems of conversion toward p-type will

L. D. Armstrong; P. Kuznetzoff

1960-01-01

92

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

93

Active control of flow and heat transfer in silicon microchannels  

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

94

Current Regulators for Large Rectifier Power Supplies Used on Electrochemical Processing Lines  

Microsoft Academic Search

Typical large silicon rectifier dc power supplies for electrochemical lines have ratings of 20 000 to over 300 000 amperes, at voltages of 50 to 1000 volts. The operating efficiency of such installations is of major economic importance, and experience has shown that the use of high-accuracy current regulation can substantially improve efficiency. Regulation is required to compensate for ac

Edward J. Cham; Roland W. Roberts

1968-01-01

95

A low-area power-efficient CMOS active rectifier for wirelessly powered medical devices  

Microsoft Academic Search

We present in this paper a new full-wave active rectifier topology. It uses a single bootstrapped capacitor to reduce the effective threshold voltage of selected MOS switches in both positive and negative input source cycles. It achieves a significant saving in silicon area while having a remarkably high power efficiency and low voltage drop. The structure does not require complex

S. Hashemi; M. Sawan; Y. Savaria

2009-01-01

96

Stable silicone oil emulsion composition, article of manufacture, and method of fabric wrinkle control  

US Patent & Trademark Office Database

Silicone emulsion comprising: at least about 0.025% and less than about 10% of silicone oil; an active amount to emulsify said silicone oil and reduce surface tension of said composition of a surfactant system; and a an effective amount of a buffering system to maintain a pH of said composition to be at least about 6 for a period of at least about 3 months, are useful for controlling wrinkles in fabrics.

Frankenbach; Gayle Marie (Cincinnati, OH); Smith; John William (Milford, OH); Trinh; Toan (Maineville, OH); Bray, Jr.; Earl (Cincinnati, OH); Winder; Lisa Catherine (Cincinnati, OH); Chang; Su Yon (Cincinnati, OH); Raleigh; Mary Ellen (Mason, OH); Corona, III; Alessandro (Maineville, OH); Burns; Anthony James (West Chester, OH); Dinniwell; Alan Robert (Mason, OH)

2005-06-21

97

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

Microsoft Academic Search

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

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

2009-01-01

98

A Quantitative Analysis of Induction Motor Performance Improvement by SCR Voltage Control  

Microsoft Academic Search

Minimum input power and maximum efficiency operation occur at characteristic slip values which can be realized for any induction motor operating at part load by properly adjusting the amplitude of the applied stator terminal voltages. These two criteria are shown to yield perceptibly different results when the motor is driven from a silicon-controlled rectifier (SCR) voltage controller. In addition, it

Timothy M. Rowan; Thomas A. Lipo

1983-01-01

99

Microstructure control of silicon nitride by seeding with rodlike [beta]-silicon nitride particles  

Microsoft Academic Search

The effect of seeding on microstructure development and mechanical properties of silicon nitride was investigated by the use of morphologically regulated rodlike [beta]-Si[sub 3]N[sub 4] single-crystal particles with a diameter of 1 [mu]m and a length of 4 [mu]m as seed crystals. Silicon nitride with a bimodal microstructure was fabricated under a relatively low nitrogen gas pressure of 0.9 MPa

Kiyoshi Hirao; Takaaki Nagaoka; Manuel E. Brito; Shuzo Kanzaki

1994-01-01

100

Lifetime Control in Silicon Through Focused Laser Beam Damage.  

National Technical Information Service (NTIS)

This report consists of two chapters. Chapter I discusses minority carrier lifetime degradation in silicon as a result of 200 keV argon and 80 keV silicon implantation. The lifetime degradation is studied for the implantation dose range of 10 to the 11th ...

G. H. Schwuttke K. H. Yang

1979-01-01

101

A technique for reducing rectifier reverse-recovery-related losses in high-voltage, high-power boost converters  

Microsoft Academic Search

A circuit technique that reduces the boost power converter losses caused by the reverse-recovery characteristics of the rectifier is described. The losses are reduced by inserting an inductor in the series path of the boost switch and the rectifier to control the di\\/dt rate of the rectifier during its turn-off. The energy from the inductor after the boost switch turn-off

Milan M. JovanoviC

1997-01-01

102

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

103

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

104

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2012 CFR

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

2012-10-01

105

46 CFR 183.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Semiconductor rectifier systems. 183.360 Section...Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2009-10-01

106

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

107

46 CFR 120.360 - Semiconductor rectifier systems.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Semiconductor rectifier systems. 120.360 Section...Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an...

2009-10-01

108

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

109

Flyback battery equalizer with voltage doubler rectifier  

Microsoft Academic Search

In this paper, a new flyback battery equalizer employing a voltage doubler rectifier is proposed. The proposed circuit transfers electric charges by utilizing the resonance between the transformer leakage inductor and secondary capacitor. Therefore, the proposed battery equalizer can reduce the switch turn off loss and snubber loss by a sinusoidal shaped current. Furthermore, the voltage stress on the rectifier

Hyoung-Suk Kim; Ki-Bum Park; Hyun-Wook Seong; Gun-Woo Moon; Myung-Joong Youn

2011-01-01

110

An improved deadbeat rectifier regulator using a neural net predictor  

Microsoft Academic Search

This paper proposes a new input current reference prediction scheme for the deadbeat control of a three-phase rectifier used in AC\\/DC\\/AC converters. The inherent lag in deadbeat control is compensated by predicting the reference resulting in better performance. The proposed predictor consists of a neural net which is trained on-line and predicts the slow varying and periodic trends of the

Farrukh Kamran; Thomas G. Habetler

1995-01-01

111

Evaporation of silicon nanoparticles under scanning tunneling microscope control  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

112

All-optical control of light on a silicon chip  

NASA Astrophysics Data System (ADS)

Photonic circuits, in which beams of light redirect the flow of other beams of light, are a long-standing goal for developing highly integrated optical communication components. Furthermore, it is highly desirable to use silicon-the dominant material in the microelectronic industry-as the platform for such circuits. Photonic structures that bend, split, couple and filter light have recently been demonstrated in silicon, but the flow of light in these structures is predetermined and cannot be readily modulated during operation. All-optical switches and modulators have been demonstrated with III-V compound semiconductors, but achieving the same in silicon is challenging owing to its relatively weak nonlinear optical properties. Indeed, all-optical switching in silicon has only been achieved by using extremely high powers in large or non-planar structures, where the modulated light is propagating out-of-plane. Such high powers, large dimensions and non-planar geometries are inappropriate for effective on-chip integration. Here we present the experimental demonstration of fast all-optical switching on silicon using highly light-confining structures to enhance the sensitivity of light to small changes in refractive index. The transmission of the structure can be modulated by up to 94% in less than 500ps using light pulses with energies as low as 25pJ. These results confirm the recent theoretical prediction of efficient optical switching in silicon using resonant structures.

Almeida, Vilson R.; Barrios, Carlos A.; Panepucci, Roberto R.; Lipson, Michal

2004-10-01

113

CGE: automatic generation of controllers in the CATHEDRAL-II silicon compiler  

Microsoft Academic Search

This paper describes the efforts done within the framework of the CATHEDRAL-II silicon compiler towards automatic controller generation. The program CGE (Controller Generation Environment) maps a microcode description generated by Atomics, an RT scheduler, onto a target controller architecture. The program produces logic, structure and layout descriptions of the constituent blocks. The controller architecture has been chosen to suit most

J. Zegers; Paul Six; Jan M. Rabaey; Hugo De Man

1990-01-01

114

Chemical control of physical properties in silicon nitride films  

NASA Astrophysics Data System (ADS)

Amorphous hydrogenated silicon nitride ( a-SiN x H y ) films were prepared by plasma-enhanced chemical vapor deposition (PECVD). The physical properties and chemical structures of the resulting materials were systematically investigated. Results reveal that the a-SiN x H y films similarly consist of four kinds of Si-N groups, including Si3N4, H-Si-N3, H2-Si-N2, and Si3-Si-N. Deposition at 13.56 MHz and 300 ?C with flow ratio of SiH4/NH3=30/30 sccm leads to the yield of Si0.39N0.38H0.23 films that exhibit excellent properties of high uniformity, high elastic modulus, moderate refractive index and optical band gap, low UV absorption, and ultralow residual stress (-0.17 MPa). Such Si0.39N0.38H0.23 films hold considerable promise for applications in solar cells and infrared sensors. In contrast, an increase of Si or N content in a-SiN x H y films will cause the degradation of the properties, so that the films are unsuitable for solar cells. Moreover, a new conception of network degree was proposed to evaluate and explain the properties of a-SiN x H y films. Particularly, this work discloses the relationships between the chemical structures and physical properties, and suggests a basic approach to the yield of a-SiN x H y films with controlled physical properties.

Xu, Xiangdong; Zhou, Dong; He, Qiong; Jiang, Yadong; Fan, Taijun; Huang, Long; Ao, Tianhong; He, Shaowei

2013-06-01

115

A new ZVS-PWM unity power factor rectifier with reduced conduction losses  

Microsoft Academic Search

This paper introduces a new single-phase high power factor rectifier, which features regulation by conventional PWM, soft commutation and instantaneous average line current control. Furthermore, thanks to the use of a single converter, instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter, a significant reduction in the conduction losses is achieved. A prototype

Alexandre Ferrari de Souza; Ivo Barbi

1995-01-01

116

A Novel HPF Voltage Source Rectifier for Variable Speed Refrigeration Systems  

Microsoft Academic Search

A novel single-phase voltage source rectifier capable to achieve high-power-factor (HPF) for variable speed refrigeration system application, is proposed in this paper. The proposed system is composed by a single-phase high-power-factor boost rectifier, with two cells in interleave connection, operating in critical conduction mode, and employing a soft-switching technique, controlled by a field programmable gate array (FPGA), associated with a

Carlos A. Canesin; F. A. S. Goncalves; E. Leandro; J. O. P. Pinto

2006-01-01

117

Charge-based silicon quantum computer architectures using controlled single-ion implantation  

Microsoft Academic Search

We report a nanofabrication, control and measurement scheme for charge-based silicon quantum computing which utilises a new technique of controlled single ion implantation. Each qubit consists of two phosphorus dopant atoms ~50 nm apart, one of which is singly ionized. The lowest two energy states of the remaining electron form the logical states. Surface electrodes control the qubit using voltage

A. S. Dzurak; L. C. L. Hollenberg; D. N. Jamieson; F. E. Stanley; C. Yang; T. M. Buhler; V. Chan; D. J. Reilly; C. Wellard; A. R. Hamilton; C. I. Pakes; A. G. Ferguson; E. Gauja; S. Prawer; G. J. Milburn; R. G. Clark

2003-01-01

118

A Monitor Wafer Based Controller For Pecvd Silicon Nitride Process On Amt 5000  

Microsoft Academic Search

In this paper we describe a monitor wafer based controller, developed for equipment without in-situ sensors. We report the controller's application to the plasma enhanced chemical vapor deposition of silicon nitride (PECVD Nitride) process run on Applied Materials Precision Reactor (AMT 5000). Using model based SQC, the controller compares product parameter measurements to model predictions to determine whether the process

P. K. Mozumder; Sharad Saxena; Dave Collins

1993-01-01

119

Platinum and Platinum Silicide Contacts on Beta-Silicon Carbide Specification.  

National Technical Information Service (NTIS)

This invention relates to contact metallization on silicon carbide, specifically, to Schottky contacts of platinum and platinum silicide on Beta-silicon carbide. It is an object of this invention to provide a rugged and thermally stable rectifying contact...

N. A. Panacolaou

1988-01-01

120

Silicon-in-silica spheres via axial thermal gradient in-fibre capillary instabilities  

NASA Astrophysics Data System (ADS)

The ability to produce small scale, crystalline silicon spheres is of significant technological and scientific importance, yet scalable methods for doing so have remained elusive. Here we demonstrate a silicon nanosphere fabrication process based on an optical fibre drawing technique. A silica-cladded silicon-core fibre with diameters down to 340?nm is continuously fed into a flame defining an axial thermal gradient and the continuous formation of spheres whose size is controlled by the feed speed is demonstrated. In particular, spheres of diameter <500?nm smaller than those produced under isothermal heating conditions are shown and analysed. A fibre with dual cores, p-type and n-type silicon, is drawn and processed into spheres. Spatially coherent break-up leads to the joining of the spheres into a bispherical silicon ‘p–n molecule’. The resulting device is measured to reveal a rectifying I–V curve consistent with the formation of a p–n junction.

Gumennik, Alexander; Wei, Lei; Lestoquoy, Guillaume; Stolyarov, Alexander M.; Jia, Xiaoting; Rekemeyer, Paul H.; Smith, Matthew J.; Liang, Xiangdong; Grena, Benjamin J.-B.; Johnson, Steven G.; Grade?ak, Silvija; Abouraddy, Ayman F.; Joannopoulos, John D.; Fink, Yoel

2013-07-01

121

Diodes and Rectifier Circuits - Solid State Principles.  

National Technical Information Service (NTIS)

Explains the principles of ac and dc current in solid state diodes and rectifiers. Uses schematics to show resistance and voltage flow. Reviews chemical and material makeup of donor and acceptor atoms. Also defines conductors, semiconductors, and insulato...

1994-01-01

122

Reverse Phase-Controlled Dimmer for Incandescent Lighting  

Microsoft Academic Search

The reverse phase-controlled dimmer is an alternate method for varying the intensity of incandescent lights. Unlike conventional phase-controlled dimmers, the thyristors are triggered into conduction immediately following the zero crossing of the ac line rather than being delayed into the half-cycle. After an appropriate delay the silicon-controlled rectifiers (SCR's) are turned off by forced commutation. Manufacturers of conventional phase-controlled dimmers

Richard M. Burkhart; David L. Ostrodka

1979-01-01

123

DQ-transformation approach for modelling and stability analysis of AC-DC power system with controlled PWM rectifier and constant power loads  

Microsoft Academic Search

In this paper a technique for analysing aircraft frequency wild power systems with constant power loads is developed and demonstrated. Power electronic based loads often behave as constant power loads, especially when feeding machine or actuator drives under current and speed control. The constant power (CP) loads can affect the stability of the power system. The problem is a particular

K.-N. Areerak; S. V. Bozhko; G. M. Asher; D. W. P. Thomas

2008-01-01

124

Multivariable adaptive control of CF4\\/O2 plasma etching of silicon nitride thin films  

Microsoft Academic Search

A two input real time feedback adaptive controller for the electron cyclotron resonance (ECR) CF4\\/O2 plasma etching of plasma enhanced chemical vapor deposited (PECVD) silicon nitride thin films is designed and simulation tested. Variations in etch rate resulting from factors such as etch chamber wall seasoning which are inherent to plasma etching necessitate the use of feedback and adaptive control

Barisj Fidan; I. G. Rosen; Tyler Parent; Anupam Madhukar

2001-01-01

125

Inward-rectifier chloride currents in Reissner's membrane epithelial cells.  

PubMed

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

2010-03-10

126

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

SciTech Connect

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

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

2012-11-06

127

Mechanisms controlling silicon isotope distribution in the Eastern Equatorial Pacific  

NASA Astrophysics Data System (ADS)

The distribution of silicon isotopes along a meridional transect at 140°W longitude in the Eastern Equatorial Pacific was used to test the hypothesis that ? 30Si of silicic acid in surface waters should correlate with net silica production rates (gross silica production minus silica dissolution) rather than rates of gross silica production due to the opposing Si isotope fractionations associated with silica production and silica dissolution. Variations in ? 30Si appeared significantly correlated with net silica production rates in equatorial surface waters and not with gross production rates. Around the Equator, values of ? 30Si as low as deep water values occurred in the upper mesopelagic in a zone of net silica dissolution and high detrital biogenic silica content, where the release of low ? 30Si silicic acid from opal dissolution would be expected to decrease ? 30Si. The ? 30Si of the deep water at 140°W appears constant for depths >2000 m and is similar to the deep water at 110°W. This study brings to light the importance of considering Si fractionation during diatom silica dissolution, the biological fractionation during silica production and physical factors such as currents and mixing with adjacent water masses when interpreting silicon isotope distributions.

Beucher, Charlotte P.; Brzezinski, Mark A.; Jones, Janice L.

2011-08-01

128

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

129

PWM Rectifier with DC Reverse-Blocking Diode for High-Reliability Generating Apparatus and Its Application to Gas Heat Pump System  

Microsoft Academic Search

High reliability generating apparatus with a PWM rectifier equipped with a DC reverse-blocking diode is proposed. The PWM rectifier adjusts the power from a permanent magnet synchronous generator by means of position sensorless control. Due to the DC diode, the PWM rectifier is shoot-through free, i.e. the switches in one arm are not broken with their simultaneous turning-on caused by

Akio Toba; Toshihiro Maeda; Kouetsu Fujita; Tomohiko Kato

2006-01-01

130

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

131

Analysis of parametric transformer with rectifier load  

SciTech Connect

This paper describes a push-pull parametric transformer constructed using a pair of orthogonal-cores. The operating characteristics of the parametric transformer with a rectifier load were analyzed based on SPICE simulations. The analysis results show good agreement with experiment. It was found that the input surge current of the full-wave rectifier circuit with a smoothing capacitor can be compensated by the parametric transformer. Use of the parametric transformer as a power stabilizer is anticipated owing to its various functions such as for voltage regulation and overload protection.

Ichinokura, O.; Jinzenji, T. (Tohoku Univ., Sendai (Japan)); Tajima, K. (Akita Univ. (Japan))

1993-03-01

132

Quantum control in silicon using coherent THz pulses  

NASA Astrophysics Data System (ADS)

It has long been known that shallow donors such as phosphorous and the other group-V elements, have a hydrogen-like optical spectrum. The main difference is that while the spectrum of atomic hydrogen lies in the visible band, the spectrum of shallow donors in silicon is downshifted to the THz frequency band. This is a direct consequence of the reduced Coulomb attraction seen by the loosely bound electron because the core electrons shield the positive donor atom nucleus, and because the electron is now moving in a dielectric material. While spectroscopy has already revealed much about the energy level structure, very little was known about the temporal dynamics of the system until now. We have used THz pulses from the FELIX free electron laser to probe these hydrogen-like levels. By exploiting the well-known pump-probe technique we have measured the characteristic lifetimes of the excited Rydberg states and found them to be of the order 200 ps. Then, by making subtle changes to the geometry of the pump-probe experimental setup we demonstrate the existence of a THz photon echo. The photon echo is a purely quantum phenomenon with no classical analogue, and it allows us to study the quantum state of the donor electron. We then show, using the photon echo, that it is possible to create a coherent superposition of the ground and excited state of the donor. Measuring the photon echo is important because it can also be used to measure a second important characteristic lifetime of the silicon-donor system, the phase decoherence time.

Lynch, Stephen A.; Greenland, P. Thornton; van der Meer, Alexander F. G.; Murdin, Benedict N.; Pidgeon, Carl R.; Redlich, Britta; Vinh, Nguyen Q.; Aeppli, Gabriel

2012-10-01

133

The Detector Control Unit: An ASIC for the monitoring of the CMS silicon tracker  

Microsoft Academic Search

The Detector Control Unit (DCU) is an ASIC developed as the central building block of a monitoring system for the CMS Tracker. Leakage currents in the Silicon detectors, power supply voltages of the readout electronics and local temperatures will be monitored in order to guarantee safe operating conditions during the 10-years lifetime in the LHC environment. All these measurements can

G. Magazzu; A. Marchioro; P. Moreira

2003-01-01

134

Controlling Dopant Profiles in Hyperdoped Silicon by Modifying Dopant Evaporation Rates During Pulsed Laser Melting  

SciTech Connect

We describe a method to control the sub-surface dopant profile in 'hyperdoped' silicon fabricated by ion implantation and pulsed laser melting. Dipping silicon ion implanted with sulfur into hydrofluoric acid prior to nanosecond pulsed laser melting leads to a tenfold increase in the rate of sulfur evaporation from the surface of the melt. This results in an 80% reduction of the near-surface dopant concentration, effectively embedding the hyperdoped region in a layer up to 180 nm beneath the surface. This method should facilitate the development of blocked impurity band devices.

Recht, D.; Sullivan, J. T.; Reedy, R.; Buonassisi, T.; Aziz, M. J.

2012-03-12

135

Hybrid Functional Studies on Impurity-Concentration-Controlled Band Engineering of Chalcogen-Hyperdoped Silicon  

NASA Astrophysics Data System (ADS)

We employ the hybrid functional method to study the impurity-concentration-controlled band engineering of chalcogen-hyperdoped silicon. The variations of defect band width and distance to the conduction band with increasing impurity concentration are given, in which at very low concentration, the reasonable depths of defect states and the energy gap compared with the experiments indicate the good accuracy of hybrid functional calculations for the band structures. For S- and Se-doped silicon, the critical concentrations for the merging of defect and conduction bands are obtained. At the key concentrations related to the insulator-to-metal transition, the characteristics of band structures are discussed.

Shao, Hezhu; Liang, Cong; Zhu, Zhen; Ning, Bo-Yuan; Dong, Xiao; Ning, Xi-Jing; Zhao, Li; Zhuang, Jun

2013-08-01

136

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

NASA Astrophysics Data System (ADS)

We describe a method to control the sub-surface dopant profile in ``hyperdoped'' silicon fabricated by ion implantation and pulsed laser melting. Dipping silicon ion implanted with sulfur into hydrofluoric acid prior to nanosecond pulsed laser melting leads to a tenfold increase in the rate of sulfur evaporation from the surface of the melt. This results in an 80% reduction of the near-surface dopant concentration, effectively embedding the hyperdoped region in a layer up to 180 nm beneath the surface. This method should facilitate the development of blocked impurity band devices.

Recht, Daniel; Sullivan, Joseph T.; Reedy, Robert; Buonassisi, Tonio; Aziz, Michael J.

2012-03-01

137

Polytype control of spin qubits in silicon carbide  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

138

A high-density array of size-controlled silicon nanodots in a silicon oxide nanowire by electron-stimulated oxygen expulsion.  

PubMed

Methods of producing Si nanodots embedded in films of silicon oxide and silicon nitride abound, but fabrication of Si nanodots in a nanowire of these materials is very rare despite the fact that nanowire architecture enhances the charge collection and transport efficiencies for solar cells and field-effect transistors. We report a novel fabrication method for a high-density array of size-controlled sillicon nanodots from a silicon oxide nanowire using electron-beam irradiation. Our results demonstrate that a highly dense phase of Si nanodots with a narrow size distribution can be made from a silicon oxide nanowire with a core-shell structure of crystalline silicon-rich oxide (c-SRO)/amorphous silicon oxide (a-SiO(2)). This new nanomaterial shows the carrier transport characteristics of a semiconductor. The initially produced amorphous Si nanodots can be readily turned into crystalline Si (c-Si) nanodots by thermal annealing. Key characteristics of c-Si nanodots such as their size, number density, and rate of nucleation and growth are easily controlled by varying the electron radiation dose and annealing temperature. Nanodot formation is mechanistically initiated by electron trapping at the c-SRO core as well as at the core-shell interface, which leads to out-diffusion of the negatively charged oxygen through Coulomb repulsion, fostering the aggregation of Si atoms. PMID:19435375

Park, Gyeong-Su; Lee, Eun Kyung; Lee, Jun Ho; Park, Juyeon; Kim, Seong Keun; Li, Xiang Shu; Park, Ju Cheol; Chung, Jae Gwan; Jeon, Woo Sung; Heo, Sung; Lee, Jae Hak; Choi, Byoung Lyong; Kim, Jong Min

2009-05-01

139

Real-time multivariable control of PECVD silicon nitride film properties  

Microsoft Academic Search

This paper reports on the application of quadrupole mass spectrometry (QMS) sensing to real-time multivariable control of film properties in a plasma-enhanced CVD silicon nitride process. Process variables believed to be most important to film deposition are defined (i.e., disilane pressure, triaminosilane pressure, and dc bias voltage) and their responses to system inputs are modeled experimentally. Then, a real-time controller

Thomas J. Knight; David W. Greve; Xu Cheng; Bruce H. Krogh

1997-01-01

140

Single-Switch Single-Phase Three-Stage Boost Rectifier  

NASA Astrophysics Data System (ADS)

Single-phase three-stage boost rectifier is studied. This has two capacitors for pumping action in each positive and negative DC line, and so the output voltage is approximately equal to that of voltage-tripler rectifier. An only active power switching device also provides the necessary control over the current. The experimental results under the current-mode control confirm that the input current can almost be waveshaped sinusoidally with a near-unity power factor operating at higher values of the output voltage.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Higake, Satoshi

141

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

142

Susceptibility and input impedance evaluation of a single phase unity power factor rectifier  

Microsoft Academic Search

This paper presents a PWM-based control system associated with a single-phase two-stage boost rectifier. Linear regulators are designed on the basis of a frequency-domain dynamical model of the converter. The input impedance and the dynamical susceptibility of the controlled system are then computed and analysed

H. Kanaan; K. Al-Haddad; R. Chaffai; L. Duguay

2000-01-01

143

A unity-power-factor three-phase PWM SCR rectifier for high-power applications in the metal industry  

Microsoft Academic Search

A new thyristor current-source rectifier that achieves unity power factor, low-current total harmonic distortion (THD), and DC-bus current and voltage control is presented. The rectifier is suitable for high-power applications such as induction heating and DC arc furnaces. It combines a traditional six-pulse thyristor bridge and a DC chopper that together solve power quality problems such as poor power factor

Ian Wallace; Ashish Bendre; Jonathan P. Nord; Giri Venkataramanan

2002-01-01

144

Demonstration of MHz-frequency operation of a monolithic self-synchronized rectifier IC in flyback DC\\/DC converter  

Microsoft Academic Search

Synchronous rectification offers an effective solution to improve efficiency of low-output-voltage flyback converters. Conventional synchronous flyback topologies using the discrete synchronous rectifier face challenges in precise timing control on the secondary side at high switching frequency. In this paper, we demonstrate the MHz-frequency operation of a flyback DC-DC converter using a new monolithic self-synchronized rectifier (SSR). The SSR IC, acting

Hongwei Jia; Osama Abdel-Rahman; Karthik Padmanabhan; Patrick Shea; Issa Batarseh; Z. John Shen

2010-01-01

145

Six Unimolecular Rectifiers and What Lies Ahead  

Microsoft Academic Search

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

Robert M. Metzger

146

Optimal locomotion of mechanical rectifier systems  

NASA Astrophysics Data System (ADS)

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

Blair, Justin T.

147

Reduced-parts-count multilevel rectifiers  

Microsoft Academic Search

Multilevel power converters have gained much attention in recent years due to their high power quality, low switching losses, and high-voltage capability. These advantages make the multilevel converter a candidate topology for the next generation of naval ship prolusion systems. The primary disadvantage of these systems is the large number of semiconductors involved. This paper presents a reduced-parts-count rectifier which

Keith A. Corzine; James R. Baker

2002-01-01

148

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

Microsoft Academic Search

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

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

1997-01-01

149

Optical control of individual carbon nanotube light emitters by spectral double resonance in silicon microdisk resonators  

NASA Astrophysics Data System (ADS)

We demonstrate integration of individual light-emitting carbon nanotubes with silicon microdisk resonators. Photons emitted from nanotubes are efficiently coupled to whispering gallery modes, circulating within the disks and lighting up their perimeters. Furthermore, we control such emission by tuning the excitation wavelength in and out of resonance with higher order modes in the same disk. Our results open up the possibilities of using nanotube emitters embedded in photonic circuits that are individually addressable through spectral double resonance.

Imamura, S.; Watahiki, R.; Miura, R.; Shimada, T.; Kato, Y. K.

2013-04-01

150

Atomically controlled processing in silicon-based CVD epitaxial growth.  

PubMed

One of the main requirements for Si-based ultrasmall device is atomic-order control of process technology. Here, we show the concept of atomically controlled processing for group IV semiconductors based on atomic-order surface reaction control in Si-based CVD epitaxial growth. Self-limiting formation of 1-3 atomic layers of group IV or related atoms after thermal adsorption and reaction of hydride gases on Si(1-x)Gex(100) (x = 0-1) surface are generalized based on the Langmuir-type model. Moreover, Si-based epitaxial growth on N, P or C atomic layer formed on Si(1-x)Gex(100) surface is achieved at temperatures below 500 degrees C. N atoms of about 4 x 10(14) cm(-2) are buried in the Si epitaxial layer within about 1 nm thick region. In the Si(0.5)Ge(0.5) epitaxial layer, N atoms of about 6 x 10(14) cm(-2) are confined within about 1.5 nm thick region. The confined N atoms in Si(1-x)Gex preferentially form Si-N bonds. For unstrained Si cap layer grown on top of the P atomic layer formed on Si(1-x)Gex(100) with P atomic amount of below about 4 x 10(14) cm(-2) using Si2H6 instead of SiH4, the incorporated P atoms are almost confined within 1 nm around the heterointerface. It is found that tensile-strain in the Si cap layer growth enhances P surface segregation and reduces the incorporated P atomic amount around the heterointerface. Heavy C atomic-layer doping suppresses strain relaxation as well as intermixing between Si and Ge at the nm-order thick Si(1-x)Gex/Si heterointerface. These results open the way to atomically controlled technology for ULSIs. PMID:22097582

Murota, Junichi; Sakuraba, Masao; Tillack, Bernd

2011-09-01

151

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

Berec, Vesna

2012-01-01

152

Topographic control on silicone surface using chemical oxidization method  

NASA Astrophysics Data System (ADS)

The paper describes a wet process for modifying the surface of polydimethylsiloxane (PDMS) using H2SO4/HNO3 solutions. The oxidation on the surface of PDMS was confirmed by the examinations of Fourier transform infrared spectrometry (FTIR), contact angle of water drop and X-ray photoelectron spectroscopy (XPS). The hydrophobic surface of pristine PDMS was not only changed to hydrophilic, but also formed wrinkles on it after chemical modification. Bilayer systems, stiff oxidized PDMS layers were capped on soft PDMS foundations, would generate easily compressive stresses due to the large difference in volumetric contraction rates and led to form wrinkles on the surface. Experimental results demonstrated the periodicity of wrinkles was controllable by controlling the duration of oxidation. Therefore, wrinkles could be arranged orderly by the guidance of external forces before oxidization. The potential technology for generating and ordering wrinkles on the PDMS surface is valuable in the applications of pressure sensors, biology, micro-optics and nano-/micro-fabrication in the future.

Shih, Teng-Kai; Ho, Jeng-Rong; Chen, Chia-Fu; Whang, Wha-Tzong; Chen, Chien-Chung

2007-10-01

153

Serum proteins and paraproteins in women with silicone implants and connective tissue disease: a case–control study  

Microsoft Academic Search

Prior studies have suggested abnormalities of serum proteins, including paraproteins, in women with silicone implants but did not control for the presence of connective-tissue disease (CTD). This retrospective case–control study, performed in tertiary-care academic centers, assessed possible alterations of serum proteins, including paraproteins, in such a population. Seventy-four women with silicone implants who subsequently developed CTD, and 74 age-matched and

Gyorgy Csako; Rene Costello; Ejaz A Shamim; Terrance P O'Hanlon; Anthony Tran; Daniel J Clauw; H James Williams; Frederick W Miller

2007-01-01

154

Space vector modulation for four-switch rectifier with compensating the effect of capacitors voltage ripple  

Microsoft Academic Search

A space vector modulation (SVM) approach is proposed to control a four-switch rectifier with power factor correction and compensating the effect of capacitors voltage ripple. The theory and performance of this method are presented, and the method effectiveness is demonstrated by extensive simulations. The simulation results show that the capacitor voltage ripple effects in the output voltage and current shaping

S. Ounie; M. R. Zolghadri

2009-01-01

155

Analysis and design of high frequency three-phase boost rectifiers  

Microsoft Academic Search

Analysis and design of high switching frequency, high efficiency, three-phase boost rectifiers are presented. A novel PWM scheme is developed to reduce switch conduction loss, switching loss, and input current ripple. An average method is proposed to calculate switch currents and input current ripple, allowing accurate prediction of switch loss, EMI emissions, and inductor loss. Soft switching, control and system

Hengchun Mao; Dushan Boroyevich; Ambatiputi Ravindra; Fred C. Lee

1996-01-01

156

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

157

FAST TRACK COMMUNICATION: Nanocrystalline silicon film growth morphology control through RF waveform tailoring  

NASA Astrophysics Data System (ADS)

We demonstrate the application of RF waveform tailoring to generate an electrical asymmetry in a capacitively coupled plasma-enhanced chemical vapour deposition system, and its use to control the growth mode of hydrogenated amorphous and nanocrystalline silicon thin films deposited at low temperature (150 °C). A dramatic shift in the dc bias potential at the powered electrode is observed when simply inverting the voltage waveform from 'peaks' to 'troughs', indicating an asymmetric distribution of the sheath voltage. By enhancing or suppressing the ion bombardment energy at the substrate (situated on the grounded electrode), the growth of thin silicon films can be switched between amorphous and nanocrystalline modes, as observed using in situ spectroscopic ellipsometry. The effect is observed at pressures sufficiently low that the collisional reduction in average ion bombardment energy is not sufficient to allow nanocrystalline growth (<100 mTorr).

Johnson, Erik V.; Verbeke, Thomas; Vanel, Jean-Charles; Booth, Jean-Paul

2010-10-01

158

Serum proteins and paraproteins in women with silicone implants and connective tissue disease: a case-control study  

PubMed Central

Prior studies have suggested abnormalities of serum proteins, including paraproteins, in women with silicone implants but did not control for the presence of connective-tissue disease (CTD). This retrospective case–control study, performed in tertiary-care academic centers, assessed possible alterations of serum proteins, including paraproteins, in such a population. Seventy-four women with silicone implants who subsequently developed CTD, and 74 age-matched and CTD-matched women without silicone implants, were assessed in the primary study; other groups were used for additional comparisons. Routine serum protein determinations and high-sensitivity protein electrophoresis and immunofixation electrophoresis were performed for detection of paraproteins. Women with silicone implants, either with or without CTD, had significantly lower serum total protein and ?1-globulin, ?2-globulin, ?-globulin, ?-globulin, and IgG levels compared with those without silicone implants. There was no significant difference, however, in the frequency of paraproteinemia between women with silicone implants and CTD (9.5%) and age-matched and CTD-matched women without silicone implants (5.4%) (odds ratio, 1.82; 95% confidence interval, 0.51–6.45). Paraprotein isotypes were similar in the two groups, and the clinical characteristics of the 13 women with paraproteinemia were comparable with an independent population of 10 women with silicone breast implants, CTD, and previously diagnosed monoclonal gammopathies. In summary, this first comprehensive study of serum proteins in women with silicone implants and CTD found no substantially increased risk of monoclonal gammopathy. Women with silicone implants, however, had unexpectedly low serum globulin and immunoglobulin levels, with or without the subsequent development of CTD. The causes and clinical implications of these findings require further investigation.

Csako, Gyorgy; Costello, Rene; Shamim, Ejaz A; O'Hanlon, Terrance P; Tran, Anthony; Clauw, Daniel J; Williams, H James; Miller, Frederick W

2007-01-01

159

Hybrid rectenna and monolithic integrated zero-bias microwave rectifier  

Microsoft Academic Search

In this study, we have developed a hybrid sensitive rectenna (rectifier + antenna) system at 2.45 GHz. To achieve this system, we have first optimized and validated a zero-bias microwave sensitive rectifier using commercial Schottky diodes. We have then optimized and achieved a 2times2 patch antenna array, which is associated to the microwave rectifier in order to validate the rectenna

Jamal Zbitou; Mohamed Latrach; Serge Toutain

2006-01-01

160

12-pulse rectifier for more electric aircraft applications  

Microsoft Academic Search

A high power density 10 kW three-phase 12-pulse rectifier is analyzed for applications in future more electric aircrafts. The experimental results, which are in good accordance with the theory, show high efficiency and low input current harmonics for a wide operating range. Furthermore, two novel rectifier topologies, which are formed by combining the passive 12-pulse rectifier with a boost stage

G. Gong; U. Drofenik; J. W. Kolar

2003-01-01

161

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.

2012-12-03

162

Silicon oxide nanowires: facile and controlled large area fabrication of vertically oriented silicon oxide nanowires for photoluminescence and sensor applications.  

PubMed

We describe a technique for the fabrication of dense and patterned arrays of aligned silicon oxide nanowires for applications in surface modification, optoelectronic, and electromechanical based devices. Conventional techniques for the fabrication of silicon oxide nanowires based on the vapor-liquid-solid (VLS) chemical vapor deposition (CVD) processes involve the use of high temperatures and catalysts. We demonstrate a technique that extends the use of a plasma thermal reactive ion etching for the fabrication of aligned silicon oxide nanowires with aspect ratios extending up to 20 and lengths exceeding 1 ?m. The process incorporates phase separated PS-b-P4VP block copolymer loaded with an iron salt. The iron salt preferentially segregates into the P4VP layer and during an O2 etch is not removed but forms a hexagonally packed array on the silicon oxide substrate. Further etching with CHF3/O2 gas mixture over time can generate nanodots, to nanopillars, and then nanowires of silicon oxide. The photoluminescence property of the as-fabricated nanowire arrays as well as the parasitic ferromagnetic effect from the iron oxide-tipped section of the wires resulting in coalescence under an scanning electron microscope (SEM) are demonstrated. This technique is simpler compared to existing VLS fabrication approaches and can be used for the direct fabrication of patterned arrays of nanowires when a laser interference ablation step is incorporated into the fabrication procedure. PMID:23915216

Alabi, Taiwo R; Yuan, Dajun; Bucknall, David; Das, Suman

2013-09-03

163

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.

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

2011-01-01

164

Rectifier-less piezoelectric micro power generator  

NASA Astrophysics Data System (ADS)

A novel thin film lead zirconate titanate Pb(Zr,Ti)O3 (PZT) MEMS energy harvesting device is designed and developed for powering autonomous wireless sensors. It is designed to harvest energy from parasitic vibrational energy sources and convert it to electrical energy via the piezoelectric effect. The new pie-shaped design for the harvester is about a size of a nickel and has a radical departure from previous design concepts. This design always generates positive tension on the PZT layer and then positive charge output throughout vibration cycles. It produces mono-polarity output charge without using any additional bridge rectifier circuitry, which will be a huge cost saving for commercial production of scaled-up products. Contrary to the high Q cantilever designs, the new design has a low Q, doubly anchored beam design, which provides a wide bandwidth of operational frequency. This will enable more robust power generation even if the frequency spectrum of the source vibration varies unexpectedly. Furthermore, the beam shape is optimized to achieve uniform strain throughout the PZT layer. To authors' knowledge, this is the first self-rectifying piezoelectric power generator at the MEMS-scale

Hajati, Arman; Kim, Sang-Gook

2008-05-01

165

Pore size control of ultrathin silicon membranes by rapid thermal carbonization.  

PubMed

Rapid thermal carbonization in a dilute acetylene (C(2)H(2)) 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

2010-10-13

166

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

NASA Astrophysics Data System (ADS)

We propose a method of controlling the growth mode in an epitaxial system. It takes advantage of differences in the vibrational frequencies of adatom-substrate bonds at terraces and steps. With a properly tuned infrared laser, one can selectively excite only the adatom-substrate bonds at steps and enhance the mobility of these adatoms, consequently promoting step-flow growth and reducing film roughness. The feasibility of this method is shown theoretically with respect to the prototype system of chemical vapor deposition growth of silicon.

Wu, Biao; Cohen, Philip I.; Feldman, L. C.; Zhang, Zhenyu

2004-03-01

167

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

168

A molecular half-wave rectifier.  

PubMed

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

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

2011-09-14

169

Spectroscopic ellipsometry (SE) based real-time control of CF4 \\/O2 plasma etching of silicon nitride  

Microsoft Academic Search

Real time feedback controllers for the electron cyclotron resonance CF4\\/O2 plasma etching of plasma enhanced chemical vapor deposited silicon nitride thin films are designed and tested. Variations in etch rate resulting from factors such as etch chamber wall seasoning which are inherent to plasma etching necessitate the use of feedback control to achieve precise and reliable etching of ultrathin films.

B. Fidan; T. Parent; G. Rosen; A. Madhukar

2000-01-01

170

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

SciTech Connect

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

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

2003-04-22

171

Preparation of Nanocrystalline Silicon in Amorphous Silicon Carbide Matrix  

Microsoft Academic Search

We have successfully prepared silicon quantum dots\\/amorphous silicon carbide multilayers by the thermal annealing of stoichiometric hydrogenated amorphous silicon carbide (a-SiC:H)\\/silicon-rich hydrogenated amorphous silicon carbide (a-Si1-xCx) multilayers. Raman scattering spectroscopy and transmission electron microscopy (TEM) revealed that silicon quantum dots were formed in only a-Si1-xCx layers. We also found that the size of silicon quantum dots can be controlled by

Yasuyoshi Kurokawa; Shinsuke Miyajima; Akira Yamada; Makoto Konagai

2006-01-01

172

Triple quantum dots as charge rectifiers.  

PubMed

We theoretically analyze electronic spin transport through a triple quantum dot in series, attached to electrical contacts, where the drain contact is coupled to the central dot. We show that current rectification is observed in the device due to current blockade. The current blocking mechanism is originated by a destructive interference of the electronic wavefunction at the drain dot. There, the electrons are coherently trapped in a singlet two-electron dark state, which is a coherent superposition of the electronic wavefunction in the source dot and in the dot isolated from the contacts. Its formation gives rise to zero current and current rectification as the voltage is swept. We analyze this behavior analytically and numerically for both zero and finite magnetic dc fields. On top of that, we include phenomenologically a finite spin relaxation rate and calculate the current numerically. Our results show that triple dots in series can be designed to behave as quantum charge rectifiers. PMID:22442135

Busl, M; Platero, G

2012-03-23

173

The Silicone Bone Cap. Bone Contouring and the Control of Adventitious Bone Formation Following Skeletal Surgery.  

National Technical Information Service (NTIS)

Isolation of terminal segments of the transected cat fibula with silicone polymer implants (93 silicone rubber caps implanted in 40 adult cats) resulted in healing at the ends of the bone segments with their intact intermedullary blood supply. Mature bone...

R. Lusskin

1970-01-01

174

Engineering independent electrostatic control of atomic-scale (?4 nm) silicon double quantum dots.  

PubMed

Scalable quantum computing architectures with electronic spin qubits hosted by arrays of single phosphorus donors in silicon require local electric and magnetic field control of individual qubits separated by ?10 nm. This daunting task not only requires atomic-scale accuracy of single P donor positioning to control interqubit exchange interaction but also demands precision alignment of control electrodes with careful device design at these small length scales to minimize cross capacitive coupling. Here we demonstrate independent electrostatic control of two Si:P quantum dots, each consisting of ?15 P donors, in an optimized device design fabricated by scanning tunneling microscope (STM)-based lithography. Despite the atomic-scale dimensions of the quantum dots and control electrodes reducing overall capacitive coupling, the electrostatic behavior of the device shows an excellent match to results of a priori capacitance calculations. These calculations highlight the importance of the interdot angle in achieving independent control at these length-scales. This combination of predictive electrostatic modeling and the atomic-scale fabrication accuracy of STM-lithography, provides a powerful tool for scaling multidonor dots to the single donor limit. PMID:22686257

Weber, Bent; Mahapatra, Suddhasatta; Watson, Thomas F; Simmons, Michelle Y

2012-07-12

175

Dopant and self-diffusion in extrinsic n-type silicon isotopically controlled heterostructures  

SciTech Connect

We present experimental results of dopant- and self-diffusion in extrinsic silicon doped with As. Multilayers of isotopically controlled {sup 28}Si and natural silicon enable simultaneous analysis of {sup 30}Si diffusion into the {sup 28}Si enriched layers and dopant diffusion throughout the multilayer structure. In order to suppress transient enhanced self- and dopant diffusion caused by ion implantation, we adopted a special approach to dopant introduction. First, an amorphous 250-nm thick Si layer was deposited on top of the Si isotope heterostructure. Then the dopant ions were implanted to a depth such that all the radiation damage resided inside this amorphous cap layer. These samples were annealed for various times and temperatures to study the impact of As diffusion and doping on Si self-diffusion. The Si self-diffusion coefficient and the dopant diffusivity for various extrinsic n-type conditions were determined over a wide temperature range. We observed increased diffusivities that we attribute to the increase in the concentration of the native defect promoting the diffusion.

Silvestri, Hughes H.; Sharp, Ian D.; Bracht, Hartmut A.; Nicols, Sam P.; Beeman, Jeff W.; Hansen, John; Nylandsted-Larsen, Arme; Haller, Eugene E.

2002-04-01

176

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

SciTech Connect

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

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

2010-11-15

177

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

178

Parallel Type Voltage Sag Compensator with Reduced Capacitor by Boost Type Power Factor Correction Rectifier  

NASA Astrophysics Data System (ADS)

A new circuit of parallel type voltage sag compensator is proposed in this paper. The proposed voltage sag compensator can reduce the necessary capacity of the energy storage capacitor for compensation by boost type power factor correction rectifier charging the capacitor during a voltage sag. As a result the proposed system can reduce the size and maintenances of the apparatus. This paper shows principle and control system of the proposed circuit. Compensation characteristics were demonstrated by simulation and experiment.

Kojima, Tetsuya; Takauchi, Toshihiko; Ise, Toshifumi; Iyoda, Isao; Kono, Yoshiyuki; Temma, Koji; Sasao, Hiroyuki; Yamasaki, Kiyomi; Inoue, Nobuyoshi; Takeuchi, Yasunori

179

Elimination of the Output Voltage Imbalance in a Half-Bridge Boost Rectifier  

Microsoft Academic Search

In this paper, a four-switch voltage-doubler boost rectifier is analyzed. A new control scheme is proposed to eliminate the output voltage imbalance when the load is unevenly distributed across the two output dc rails. Unipolar pulsewidth modulation switching patterns are adopted to slow down the discharging rate of the output capacitor with the lower voltage. No dc or out-of-phase component

Yu-Kang Lo; Chin-Tse Ho; Jian-Min Wang

2007-01-01

180

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

181

Sensorless optimization of dead times in DC-DC converters with synchronous rectifiers  

Microsoft Academic Search

This paper introduces an approach to achieve optimum dead times in dc-dc converters with synchronous rectifiers without sensing any of the power-stage signals other than the output voltage. The dead times are adjusted adaptively to minimize the duty-cycle command, which results in maximization of the converter efficiency. The method is particularly well suited for digital controller implementation, requiring no additional

Vahid Yousefzadeh; Dragan Maksimovic ´

2006-01-01

182

Evaluation of ultra-compact rectifiers for low power, high-speed, permanent-magnet generators  

Microsoft Academic Search

Literature reports several future portable and distributed power supplies in the watt to kilowatt range based on rotating machinery equipped with a variable-speed permanent-magnet generator. In order to generate a constant dc voltage, an ultra-compact, highly efficient, low power rectifier is required. In this paper, different topologies are compared concerning losses, volume and control complexity. The most suitable, the half

D. Krahenbuhl; C. Zwyssig; K. Bitterli; M. Imhof; J. W. Kolar

2009-01-01

183

Single-Phase Voltage-Quadrupler Rectifier Using Only One Dual-Switch Power Module  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier using only one dual-switch power module is presented. This is based on the half-bridge converter and the higher output voltage can easily be obtained by introducing the pumping action. The prototype, employing a power module with two insulated-gate bipolar transistors, is implemented. The experimental results under the current-mode control confirm that the input current can be wave-shaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Matsumoto, Hirokazu; Haraguchi, Takahiro

184

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds  

NASA Astrophysics Data System (ADS)

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 single phase at a decomposition temperature <440 °C under the condition without sodium metal vapor. The type I clathrate compound was decomposed to crystalline Si above 520 °C. The type II clathrate compound was thermally more stable, and retained at least up to 550 °C in vacuum.

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

2009-01-01

185

Current self-complianced and self-rectifying resistive switching in Ag-electroded single Na-doped ZnO nanowires.  

PubMed

We demonstrate current self-complianced and self-rectifying bipolar resistive switching in an Ag-electroded Na-doped ZnO nanowire device. The resistive switching is controlled by the formation and rupture of an Ag nanoisland chain on the surface along the Na-doped ZnO nanowire. Na-doping plays important roles in both the self-compliance and self-rectifying properties. PMID:23456175

Qi, Jing; Huang, Jian; Paul, Dennis; Ren, Jingjian; Chu, Sheng; Liu, Jianlin

2013-04-01

186

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

PubMed

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

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

2013-04-18

187

Bridgeless isolated PFC rectifier using bidirectional switch and dual output windings  

Microsoft Academic Search

In this paper, a family of bridgeless power factor correction (PFC) rectifier which configures isolated single- stage is proposed. The proposed PFC rectifiers utilize bidirectional switch to handle both positive and negative input voltage without bridge diodes. Dual output windings of transformer enable the rectifiers dispense with any additional magnetic component. As a member of the proposed rectifier family, a

Jong-Won Shin; Jong-bok Baek; Bo-Hyung Cho

2011-01-01

188

Suspended heated silicon platform for rapid thermal control of surface reactions with application to carbon nanotube synthesis  

Microsoft Academic Search

Rapid continuous thermal control of chemical reactions such as those for chemical vapor deposition CVD growth of nanotubes and nanowires cannot be studied using traditional reactors such as tube furnaces, which have large thermal masses. We present the design, modeling, and verification of a simple, low-cost reactor based on resistive heating of a suspended silicon platform. This system achieves slew

Lucas van Laake; Anastasios John Hart; Alexander H. Slocum

2007-01-01

189

Suspended heated silicon platform for rapid thermal control of surface reactions with application to carbon nanotube synthesis  

Microsoft Academic Search

Rapid continuous thermal control of chemical reactions such as those for chemical vapor deposition (CVD) growth of nanotubes and nanowires cannot be studied using traditional reactors such as tube furnaces, which have large thermal masses. We present the design, modeling, and verification of a simple, low-cost reactor based on resistive heating of a suspended silicon platform. This system achieves slew

Lucas van Laake; Anastasios John Hart; Alexander H. Slocum

2007-01-01

190

Noise rectifier based on the two-dimensional electron gas  

SciTech Connect

The dc voltage observed at low temperatures in a 2D electron sample in the absence of noticeable external excitations [1] is accounted by the Schottky contact rectification of the noise generated in the measuring circuit. The rectified voltage is shown to depend on the asymmetry of the contact pair. The dependence of the rectified voltage on the noise amplitude first follows the trivial quadratic law, then exhibits a nearly linear behavior, and finally, levels off.

Cheremisin, M. V., E-mail: tcher_max@yahoo.com [Ioffe Physical-Technical Institute (Russian Federation)

2012-09-15

191

A simple system for remote monitoring of cathodic rectifiers  

SciTech Connect

Efforts to remotely monitor Con Edison's (New York, New York) cathodic protection (CP) rectifiers began in 1988 with the use of a monitor made specifically for this purpose. The company sought an effective, economic system to remotely monitor its cathodic protection rectifiers. This article describes the systems tried, especially the computerized system that proved most reliable and economical, while complying with federal and state regulations.

Dolan, M.P. (Consolidated Edison Co. of New York Inc., New York (United States))

1993-05-01

192

Engineering the size and density of silicon agglomerates by controlling the initial surface carbonated contamination  

NASA Astrophysics Data System (ADS)

Actually, thermally induced thin-films dewetting silicon in the silicon-on-insulator is a way to obtain silicon agglomerates with a size and a density fixed by the silicon film thickness. In this paper we report a new method to monitor both the size and the density of the Si agglomerates thanks to the deposition of a carbon-like layer. We show that using a 5-nm thick layer of silicon and additional ?1-nm carbonated layer; we obtain agglomerates sizes ranging from 35 nm to 60 nm with respectively an agglomerate density ranging from 38 ?m-2 to 18 ?m-2. Additionally, for the case of strained silicon films an alternative dewetting mechanism can be induced by monitoring the chemical composition of the sample surface.

Borowik, ?.; Chevalier, N.; Mariolle, D.; Martinez, E.; Bertin, F.; Chabli, A.; Barbé, J.–C.

2013-04-01

193

Controlled growth of silicon nanowires synthesized via solid–liquid–solid mechanism  

Microsoft Academic Search

The growth of silicon nanowires using solid–liquid–solid method is described. In this method, silicon substrates coated with a thin layer of gold were heat treated in nitrogen ambient. Gold particles started to diffuse into the silicon substrate and Au–Si alloy formed at the interface. The alloy would have molten to form liquid droplets on the substrate when temperature increases above

Y. Y. Wong; M. Yahaya; M. Mat Salleh; B. Yeop Majlis

2005-01-01

194

Polarization-controlled excitation of multilevel plasmonic nano-circuits using single silicon nanowire.  

PubMed

We propose a surface plasmon polarization-controlled beam splitter based on plasmonic slot waveguides (PSWs). It couples light of different polarizations from a silicon nanowire into multilevel plasmonic networks. Two orthogonal PSWs are utilized as the guiding waveguides for each polarization. The proposed structure overcomes inherent polarization limitation in plasmonic structures by providing multilevel optical signal processing. This ability of controlling polarization can be exploited to achieve 3-D multilevel plasmonic circuits and polarization controlled chip to chip channel. Our device is of a compact size and a wide band operation. The device utilizes both quasi-TE and quasi-TM polarizations to allow for increased optical processing capability. The crosstalk is minimal between the two polarizations propagating in two different levels. We achieve good transmission efficiency at a wavelength of 1.55 µm for different polarizations. We analyze and simulate the structure using the FDTD method. The proposed device can be utilized in integrated chips for optical signal processing and optical computations. PMID:22714235

El Sherif, Mohamed H; Ahmed, Osman S; Bakr, Mohamed H; Swillam, Mohamed A

2012-05-21

195

Chemically doped random network carbon nanotube p-n junction diode for rectifier.  

PubMed

Semiconductors with higher carrier mobility and carrier density are required to fabricate a p-n junction diode for high-speed device operation and high-frequency signal processing. Here, we use a chemically doped semiconducting single-walled carbon nanotube (SWCNT) random network for a field effect transistor (FET) and demonstrate a rectifier operated at a wide range of frequencies by fabricating a p-n junction diode. The p-n diode was fabricated by using a pristine p-type SWCNT-FET where half was covered by SiO(2) and the other half was chemically doped by using benzyl viologen molecules, which was converted into an n-type channel. The half-wave rectifier of the random network SWCNT p-n junction diode clearly highlights the device operation under high input signal frequencies up to 10 MHz with very low output distortion, which a commercial silicon p-n junction diode cannot access. These results indicate that the random network SWCNT p-n junction diodes can be used as building blocks of complex circuits in a range of applications in microelectronics, optoelectronics, sensors, and other systems. PMID:22040293

Biswas, Chandan; Lee, Si Young; Ly, Thuc Hue; Ghosh, Arunabha; Dang, Quoc Nguyen; Lee, Young Hee

2011-11-03

196

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

197

Dynamic nuclear polarization of {sup 29}Si nuclei in isotopically controlled phosphorus doped silicon  

SciTech Connect

Dynamic nuclear polarization (DNP) of {sup 29}Si nuclei in isotopically controlled silicon single crystals with the {sup 29}Si isotope abundance f{sub 29Si} varied from 1.2% to 99.2% is reported. It was found that both the DNP enhancement and {sup 29}Si nuclear spin-lattice relaxation time under saturation of the electron paramagnetic resonance transitions of phosphorus donors increase with the decrease in the {sup 29}Si abundance. A remarkably large steady-state DNP enhancement, E{sup ss}=2680 which is comparable to the theoretical upper limit of 3310, has been achieved through the ''resolved'' solid effect that has been identified clearly in the f{sub 29Si}=1.2% sample. The DNP enhancement depends not only on the {sup 29}Si abundance but also on the electron spin-lattice relaxation time that can be controlled by temperature and/or illumination. The linewidth of {sup 29}Si NMR spectra after DNP shows a linear dependence on f{sub 29Si} for f{sub 29Si}{<=}10% and changes to a square-root dependence for f{sub 29Si}{>=}50%. Comparison of experimentally determined nuclear polarization time with nuclear spin diffusion coefficients indicates that the rate of DNP is limited by the polarization transfer rather than by spin diffusion.

Hayashi, Hiroshi; Itahashi, Tatsumasa; Itoh, Kohei M.; Vlasenko, Leonid S.; Vlasenko, Marina P. [School of Fundamental Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); A. F. Ioffe Physico-Technical Institute, 194021 Saint Petersburg (Russian Federation)

2009-07-15

198

Surfaces with high solar reflectance and high thermal emittance on structured silicon for spacecraft thermal control  

Microsoft Academic Search

Presented here is an examination of unstructured and structured (by anisotropic etching), monocrystalline silicon wafers coated with sputter deposited aluminum and chemical vapor deposited silicon dioxide for high solar reflectance and high thermal emittance, respectively. The topography of the samples was characterized with optical and scanning electron microscopy. Optical properties were examined with reflectance and transmittance spectroscopy, partly by usage

Tobias Böhnke; Henrik Kratz; Annette Hultåker; Johan Köhler; Marika Edoff; Arne Roos; Carl-Gustaf Ribbing; Greger Thornell

2008-01-01

199

Controlled assembly of DNA nanostructures on silanized silicon and mica surfaces for future molecular devices  

Microsoft Academic Search

In order to establish key technology for future molecular devices, we have explored the assembly behaviour of ?-deoxyribonucleic acid (DNA) molecules adsorbed on silanized mica and silanized oxide silicon surfaces by using atomic force microscopy (AFM). AFM experiments show that ?-DNA molecules can be hardly adsorbed on untreated mica and oxidized silicon surfaces, but can be strongly adsorbed onto aminosilanized

Zhanwen Xiao; Mingxiang Xu; Taizo Ohgi; Keisuke Sagisaka; Daisuke Fujita

2002-01-01

200

Molecular rectifiers based on donor/acceptor assemblies: effect of orientation of the components' magnetic moments.  

PubMed

In forming donor/acceptor assemblies that act as molecular rectifiers, we have introduced magnetic organic molecules as electron-donating and electron-accepting moieties. We have oriented the magnetic moment of the donor and acceptor components separately and immobilized them (and their moments) so that the molecular assemblies that act as rectifiers could be formed with moments mutually parallel or anti-parallel to each other. We have characterized the molecular assemblies formed on an electrode with a scanning tunneling microscope tip. Such donor/acceptor assemblies with a control over the orientation of moments of the components provided unique systems to study the effect of the nature of alignment on molecular rectifiers. We have observed that the rectification ratio increased in junctions with moments of the components being parallel to each other. The improvement in the rectification ratio has been explained in terms of an efficient electron-transfer process in a moment-aligned junction between the donor and acceptor moieties. PMID:23760260

Bera, Abhijit; Pal, Amlan J

2013-06-11

201

Input-output harmonic elimination of the PWM Boost Type Rectifier under unbalanced operating conditions  

NASA Astrophysics Data System (ADS)

It is the purpose of this research to propose a new control strategy to improve the performance of the PWM Boost Type Rectifier under unbalanced operating conditions. A complete analysis for the input-output harmonic elimination of the Boost Type Rectifier is presented. An analytical solution for harmonic elimination under unbalanced input voltages and balanced input impedances is obtained. Based on the analysis of the open loop configuration, a closed loop solution is proposed. The proposed technique maintains a high quality of input and output waveforms under unbalanced input voltages and balanced input impedances when this method is applied. The theoretical and experimental results show excellent agreement. The proposed method is useful particularly in applications with PWM inverters for variable speed drives, where the huge second harmonic at the dc link can cause significant torque pulsations in electrical machines. This research also extends to a more general case. In general, both input voltages and input impedances can be unbalanced. As in the previous case, the proposed solution is analyzed in the closed loop configuration. Again, the high quality of the input and output waveforms is maintained under a completely unbalanced system. The range of imbalance in both input voltages and input impedances, for which the proposed method would still be valid, is analyzed in detail. It has been shown that the PWM Boost Type Rectifier can operate from the single-phase power supply (the special case of imbalance) when the proposed method is applied. This is an extremely important contribution, since it means that the PWM Boost Type Rectifier can operate from the center-tapped transformer and still maintain high quality input and output characteristics. This generalized method for input-output harmonic elimination under unbalanced input voltages and unbalanced input impedances also allows power factor correction. This general case is very useful under severe fault conditions in the power system.

Stankovic, Ana Vladan

202

Silicon-in-silica spheres via axial thermal gradient in-fibre capillary instabilities.  

PubMed

The ability to produce small scale, crystalline silicon spheres is of significant technological and scientific importance, yet scalable methods for doing so have remained elusive. Here we demonstrate a silicon nanosphere fabrication process based on an optical fibre drawing technique. A silica-cladded silicon-core fibre with diameters down to 340?nm is continuously fed into a flame defining an axial thermal gradient and the continuous formation of spheres whose size is controlled by the feed speed is demonstrated. In particular, spheres of diameter <500?nm smaller than those produced under isothermal heating conditions are shown and analysed. A fibre with dual cores, p-type and n-type silicon, is drawn and processed into spheres. Spatially coherent break-up leads to the joining of the spheres into a bispherical silicon 'p-n molecule'. The resulting device is measured to reveal a rectifying I-V curve consistent with the formation of a p-n junction. PMID:23900398

Gumennik, Alexander; Wei, Lei; Lestoquoy, Guillaume; Stolyarov, Alexander M; Jia, Xiaoting; Rekemeyer, Paul H; Smith, Matthew J; Liang, Xiangdong; Grena, Benjamin J-B; Johnson, Steven G; Grade?ak, Silvija; Abouraddy, Ayman F; Joannopoulos, John D; Fink, Yoel

2013-01-01

203

Stable atom-scale junctions on silicon fabricated by kinetically controlled electrochemical deposition and dissolution.  

PubMed

Metallic atom-scale junctions (ASJs) constitute the natural limit of nanowires, in which the limiting region of conduction is only a few atoms wide. They are of interest because they exhibit ballistic conduction and their conductance is extraordinarily sensitive to molecular adsorption. However, identifying robust and regenerable mechanisms for their production is a challenge. Gold ASJs have been fabricated electrochemically on silicon using an iodide-containing medium to control the kinetics. Extremely slow electrodeposition or electrodissolution rates were achieved and used to reliably produce ASJs with limiting conductance <5 G(0). Starting from a photolithographically fabricated, Si(3)N(4)-protected micrometer-scale Au bridge between two contact electrodes, a nanometer-scale gap was prepared by focused ion beam milling. The opposing Au faces of this construct were then used in an open-circuit working electrode configuration to produce Au ASJs, either directly or by first overgrowing a thicker Au nanowire and electrothinning it back to an ASJ. Gold ASJs produced by either approach exhibit good stabilityin some cases being stable over hours at 300 Kand quantized conductance properties. The influence of deposition/dissolution potential and supporting electrolyte on the stability of ASJs are considered. PMID:19206360

Shi, Ping; Bohn, Paul W

2008-08-01

204

Luminescence in amorphous silicon p-i-n diodes under double-injection dispersive-transport-controlled recombination  

SciTech Connect

The temperature and electric-field dependence of the forward bias current and the electroluminescence (EL) in hydrogenated amorphous silicon (a-Si:H) p-i-n and n-i-p diodes have been studied. Both the current and the EL efficiency temperature dependence show three regions depending on either hopping-controlled or multiple-trapping or ballistic transport mechanisms. Comparing the thermalization-controlled geminate recombination processes of photoluminescence to the features of EL, the differences can be explained by transport-controlled nongeminate recombination in trap-rich materials. {copyright} {ital 1997} {ital The American Physical Society}

Han, D.; Wang, K.; Yeh, C. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, North Carolina 27599-3255 (United States); Yang, L. [Solarex A Business Unit of Amoco/Enron Solar, Newtown, Pennsylvania 18940 (United States); Deng, X. [Energy Conversion Devices, Incorporated, 1675 West Maple Road, Troy, Michigan 48084 (United States); Von Roedern, B. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

1997-06-01

205

Single-Phase Boost Rectifier Adding a Capacitor for Pumping Action in DC Circuit  

NASA Astrophysics Data System (ADS)

To obtain higher DC output voltage, a single-phase boost rectifier adding a capacitor for pumping action in DC circuit is studied. This gives two-stage boost operation by means of inductive and capacitive energy storage/transfer mechanisms under the high-frequency switching. The experimental prototype, employing an insulated-gate bipolar transistor as an active power switching device and a PI controller for output voltage regulation, is implemented to investigate the operation. The experimental results confirm that the input current can almost be waveshaped sinusoidally with a near-unity power factor by the current-mode control.

Oishi, Hayato; Neba, Yasuhiko; Ishizaka, Kouichi; Itoh, Ryozo

206

Improvement in Input Current Distortion of Single-Phase Two-Stage Boost Rectifier  

NASA Astrophysics Data System (ADS)

An improvement in the input current distortion of single-phase two-stage boost rectifier is studied. To cause the input current to follow its sinusoidal reference by means of current-mode control, a capacitor voltage is superimposed upon that of the supply when the switches are turned on. The experimental prototype, employing two insulated-gate bipolar transistors as active power switching devices and PI controller for output voltage regulation, is implemented to investigate the operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor independent of the working conditions.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Maeda, Tsuyoshi

207

Controlled localised melting in silicon by high dose germanium implantation and flash lamp annealing  

NASA Astrophysics Data System (ADS)

High intensity light pulse irradiation of monocrystalline silicon wafers is usually accompanied by inhomogeneous surface melting. The aim of the present work is to induce homogeneous buried melting in silicon by germanium implantation and subsequent flash lamp annealing. For this purpose high dose, high energy germanium implantation has been employed to lower the melting temperature of silicon in a predetermined depth region. Subsequent flash lamp irradiation at high energy densities leads to local melting of the germanium rich buried layer, whereby the thickness of the molten layer depends on the irradiation energy density. During the cooling down epitaxial crystallization takes place resulting in a largely defect-free layer. The combination of buried melting and dopant segregation has the potential to produce unusually buried doping profiles or to create strained silicon structures.

Voelskow, Matthias; Skorupa, Wolfgang; Pezoldt, Jörg; Kups, Thomas

2009-05-01

208

Optimization of silicon-germanium TFT's through the control of amorphous precursor characteristics  

Microsoft Academic Search

Polycrystalline thin-film transistors (TFT's) are promising for use as high-performance pixel and integrated driver transistors for active matrix liquid crystal displays (AMLCD's). Silicon-germanium is a promising candidate for use as the channel material due to its low thermal budget requirements. The binary nature of the silicon-germanium system complicates the optimization of the channel deposition conditions. To date, little work has

Vivek Subramanian; Krishna C. Saraswat

1998-01-01

209

Stable cycling of double-walled silicon nanotube battery anodes through solid-electrolyte interphase control  

NASA Astrophysics Data System (ADS)

Although the performance of lithium ion-batteries continues to improve, their energy density and cycle life remain insufficient for applications in consumer electronics, transport and large-scale renewable energy storage. Silicon has a large charge storage capacity and this makes it an attractive anode material, but pulverization during cycling and an unstable solid-electrolyte interphase has limited the cycle life of silicon anodes to hundreds of cycles. Here, we show that anodes consisting of an active silicon nanotube surrounded by an ion-permeable silicon oxide shell can cycle over 6,000 times in half cells while retaining more than 85% of their initial capacity. The outer surface of the silicon nanotube is prevented from expansion by the oxide shell, and the expanding inner surface is not exposed to the electrolyte, resulting in a stable solid-electrolyte interphase. Batteries containing these double-walled silicon nanotube anodes exhibit charge capacities approximately eight times larger than conventional carbon anodes and charging rates of up to 20C (a rate of 1C corresponds to complete charge or discharge in one hour).

Wu, Hui; Chan, Gerentt; Choi, Jang Wook; Ryu, Ill; Yao, Yan; McDowell, Matthew T.; Lee, Seok Woo; Jackson, Ariel; Yang, Yuan; Hu, Liangbing; Cui, Yi

2012-05-01

210

Stable cycling of double-walled silicon nanotube battery anodes through solid-electrolyte interphase control.  

PubMed

Although the performance of lithium ion-batteries continues to improve, their energy density and cycle life remain insufficient for applications in consumer electronics, transport and large-scale renewable energy storage. Silicon has a large charge storage capacity and this makes it an attractive anode material, but pulverization during cycling and an unstable solid-electrolyte interphase has limited the cycle life of silicon anodes to hundreds of cycles. Here, we show that anodes consisting of an active silicon nanotube surrounded by an ion-permeable silicon oxide shell can cycle over 6,000 times in half cells while retaining more than 85% of their initial capacity. The outer surface of the silicon nanotube is prevented from expansion by the oxide shell, and the expanding inner surface is not exposed to the electrolyte, resulting in a stable solid-electrolyte interphase. Batteries containing these double-walled silicon nanotube anodes exhibit charge capacities approximately eight times larger than conventional carbon anodes and charging rates of up to 20C (a rate of 1C corresponds to complete charge or discharge in one hour). PMID:22447161

Wu, Hui; Chan, Gerentt; Choi, Jang Wook; Ryu, Ill; Yao, Yan; McDowell, Matthew T; Lee, Seok Woo; Jackson, Ariel; Yang, Yuan; Hu, Liangbing; Cui, Yi

2012-03-25

211

A diode rectifier series tap on an HVDC line  

SciTech Connect

Electrical energy of a rather small isolated source in vicinity of an HVDC line may be transmitted via the same line by application of a series tapping station. For such purposes, a diode rectifier series tap, which offers considerable savings as well as a high degree of reliability, is proposed and discussed in this paper. Digital simulation studies have been carried out for a 10% diode rectifier series tap on an otherwise point-to-point HVDC system (Manitoba Hydro's Bipole II) using Electromagnetic Transients Program (EMTP). The results reveal the technical feasibility of the idea, without the need for any dc circuit breaker.

Arabi, S.; Tarnawecky, M.Z.

1985-09-01

212

Two-photon indirect optical injection and two-color coherent control in bulk silicon  

NASA Astrophysics Data System (ADS)

Using an empirical pseudopotential description of electron states and an adiabatic bond charge model for phonon states in bulk silicon, we theoretically investigate two-photon indirect optical injection of carriers and spins and two-color coherent control of the motion of the injected carriers and spins. For two-photon indirect carrier and spin injection, we identify the selection rules of band edge transitions, the injection in each conduction band valley, and the injection from each phonon branch at 4 and 300 K. At 4 K, the TA-phonon-assisted transitions dominate the injection at low photon energies and the TO-phonon-assisted transitions at high photon energies. At 300 K, the former dominates at all photon energies of interest. The carrier injection shows anisotropy and linear-circular dichroism with respect to the light propagation direction. For light propagating along the <001> direction, the carrier injection exhibits valley anisotropy, and the injection into the Z conduction band valley is larger than that into the X and Y valleys. For ?- light propagating along the <001> (<111>) direction, the degree of spin polarization gives a maximum value about 20% (6%) at 4 K and -10% (20%) at 300 K, and at both temperature shows abundant structure near the injection edges due to contributions from different phonon branches. For two-color coherent current injection with an incident optical field composed of a fundamental frequency and its second harmonic, the response tensors of the electron (hole) charge and spin currents are calculated at 4 and 300 K. We show the current control for three different polarization scenarios: For cocircularly polarized beams, the direction of the charge current and the polarization direction of the spin current can be controlled by a relative-phase parameter; for the collinearly and cross-linearly polarized beams, the current amplitude can be controlled by that parameter. The spectral dependence of the maximum swarm velocity shows that the direction of the charge current reverses under an increase in photon energy.

Cheng, J. L.; Rioux, J.; Sipe, J. E.

2011-12-01

213

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

214

Investigation of UHF low power rectifier based on resonant tunneling diode  

Microsoft Academic Search

UHF low power rectifier is considered. Influence of nonlinear parts' VAC vs. rectifier parameters is investigated. Conversion efficiency increased 3...10 times by means of resonant tunneling diode using. Experimental verification of mathematical model is carried out.

Yu. A. Ivanov; S. A. Meshkov; V. Yu. Sinyakin; I. A. Fedorenko; N. V. Fedorkova; V. D. Shashurin

2010-01-01

215

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

NASA Astrophysics Data System (ADS)

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

Cui, Zhiwei; Gao, Feng; Qu, Jianmin

2013-02-01

216

The use of pressure and silicone in hypertrophic scar management in burns patients: a pilot randomized controlled trial.  

PubMed

This pilot study investigates whether pressure and silicone therapy used simultaneously are more effective in treating multiple characteristics of hypertrophic scars than pressure alone. A pilot randomized controlled trial was conducted. Twenty-two participants with hypertrophic burn scars were randomized to receive Jobskin pressure garments and Mepiform silicone sheeting or Jobskin pressure garments alone. The Vancouver Scar Scale (VSS) was used to measure multiple scar characteristics at baseline, week 12, and week 24. No statistically significant difference was found in the rate of change of the VSS scores between the pressure therapy (PT) group and the pressure therapy and silicone group at week 12 or week 24; however, the mean scores of both groups reduced over 24 weeks. There were no statistically significant changes in the VSS subscores (scar height, vascularity, pliability, and pigmentation) from baseline to week 12 or week 24. A statistically significant relationship was observed between the VSS score and TBSA burned (<30%) in the PT group at baseline (P<.05), over 12 weeks (P<.05), and over 24 weeks (P<.05). Given the limitations of this study, especially the small sample size, further research is necessary before any firm conclusions can be drawn on this therapy approach. However, this pilot study has discussed the recurring issues in the research regarding these controversial treatments and has yielded potential for further investigation in a fully powered randomized controlled trial. PMID:19506491

Harte, Daniel; Gordon, Jude; Shaw, Maxine; Stinson, May; Porter-Armstrong, Alison

217

On the Controlling Mechanism of Preferential Orientation of Polycrystalline-Silicon Thin Films Grown by Aluminum-Induced Crystallization  

NASA Astrophysics Data System (ADS)

We investigated the controlling mechanism of preferential orientation in polycrystalline silicon (poly-Si) on glass substrate by Al-induced crystallization using an in situ monitoring system and electron backscattered diffraction (EBSD) measurements. Poly-Si film with (111)-preferential orientation was obtained by the layer exchange of the initial amorphous silicon (a-Si)/Al/glass into Al/poly-Si/glass. Cross-sectional EBSD revealed that Al crystal grains are much smaller than those of Si, and randomly oriented without any epitaxial relationship between (111)-oriented Si despite the fact that (111)-oriented Si is believed to originate from epitaxial growth on ?-Al2O3/Al(111). This suggests that another mechanism such as minimization of surface energy affects the formation of (111)-oriented poly-Si.

Jung, Mina; Okada, Atsushi; Saito, Takanobu; Suemasu, Takashi; Usami, Noritaka

2010-09-01

218

Doping controlled roughness and defined mesoporosity in chemically etched silicon nanowires with tunable conductivity  

NASA Astrophysics Data System (ADS)

By using Si(100) with different dopant type (n++-type (As) or p-type (B)), we show how metal-assisted chemically etched (MACE) nanowires (NWs) can form with rough outer surfaces around a solid NW core for p-type NWs, and a unique, defined mesoporous structure for highly doped n-type NWs. We used high resolution electron microscopy techniques to define the characteristic roughening and mesoporous structure within the NWs and how such structures can form due to a judicious choice of carrier concentration and dopant type. The n-type NWs have a mesoporosity that is defined by equidistant pores in all directions, and the inter-pore distance is correlated to the effective depletion region width at the reduction potential of the catalyst at the silicon surface in a HF electrolyte. Clumping in n-type MACE Si NWs is also shown to be characteristic of mesoporous NWs when etched as high density NW layers, due to low rigidity (high porosity). Electrical transport investigations show that the etched nanowires exhibit tunable conductance changes, where the largest resistance increase is found for highly mesoporous n-type Si NWs, in spite of their very high electronic carrier concentration. This understanding can be adapted to any low-dimensional semiconducting system capable of selective etching through electroless, and possibly electrochemical, means. The process points to a method of multiscale nanostructuring NWs, from surface roughening of NWs with controllable lengths to defined mesoporosity formation, and may be applicable to applications where high surface area, electrical connectivity, tunable surface structure, and internal porosity are required.

McSweeney, W.; Lotty, O.; Mogili, N. V. V.; Glynn, C.; Geaney, H.; Tanner, D.; Holmes, J. D.; O'Dwyer, C.

2013-07-01

219

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

220

The Use of the Copper-Oxide Rectifier for Instrument Purposes  

Microsoft Academic Search

Mention is made of the need for high sensitivity a-c measuring instruments and the development of the copper-oxide rectifier as a ready means of obtaining high sensitivity without sacrificing other desirable characteristics. Possibilities and limitations of half-wave rectification are discussed. An analysis is made of the copper-oxide full-wave instrument rectifier. Characteristics of this rectifier and of rectifier instruments under varying

J. Sahagen

1931-01-01

221

DC ripple current reduction on a single-phase PWM voltage-source rectifier  

Microsoft Academic Search

A novel topology of single-phase pulsewidth modulation (PWM) voltage-source rectifier capable of achieving not only a sinusoidal input current, but also a zero-ripple output current, is presented. The rectifier consists of a conventional single-phase PWM voltage-source rectifier, a pair of additional switches and an inductor. Hence, the proposed rectifier requires neither a large DC capacitor nor a passive L-C resonant

Toshihisa Shimizu; Yasuhiro Jin; Gunji Kimura

2000-01-01

222

Stability Analysis of a Rectifier-Inverter Induction Motor Drive  

Microsoft Academic Search

A stability study of a rectifier-inverter induction motor drive system is performed by neglecting the harmonic content of the stator voltages and applying Nyquist stability criterion to the small- displacement equations obtained by linearization about an operating point. This investigation reveals that system instability can occur over a wide speed range if the system parameters are improperly selected. It appears

Thomas Lipo; Paul Krause

1969-01-01

223

Rectified Brownian movement in molecular and cell biology  

Microsoft Academic Search

A unified model is presented for rectified Brownian movement as the mechanism for a variety of putatively chemomechanical energy conversions in molecular and cell biology. The model is established by a detailed analysis of ubiquinone transport in electron transport chains and of allosteric conformation changes in proteins. It is applied to P-type ATPase ion transporters and to a variety of

Ronald F. Fox

1998-01-01

224

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

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

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

225

Comparison of Rectified and Unrectified Sockets for Transtibial Amputees  

PubMed Central

The current method for fabricating prosthetic sockets is to modify a positive mold to account for the non-homogeneity of the residual limb to tolerate load (i.e., rectified socket). We tested unrectified sockets by retaining the shape of the residual limb, except for a distal end pad, using an alginate gel process instead of casting. This investigation compared rectified and unrectified sockets. Forty-three adults with unilateral transtibial amputations were tested after randomly wearing both rectified and unrectified sockets for at least 4 weeks. Testing included a gait analysis, energy expenditure and Prosthesis Evaluation Questionnaire (PEQ). Results indicated no differences between sockets for gait speed and timing, gait kinematics and kinetics, and gait energy expenditure. There were also no differences in the Prosthetic Evaluation Questionnaire and 16 subjects selected the rectified socket, 25 selected the unrectified socket, and 2 subjects selected to use both sockets as their exit socket. Results seemed to indicate that more than one paradigm exists for shaping prosthetic sockets, and this paradigm may be helpful in understanding the mechanisms of socket fit. The alginate gel fabrication method was simpler than the traditional method. The method could be helpful in other countries where prosthetic care is lacking, may be helpful with new amputees, and may be helpful in typical clinics to reduce costs and free the prosthetist to focus more time on patient needs.

Engsberg, Jack R.; Sprouse, S. Wayne; Uhrich, Mary L.; Ziegler, Barbara R.; Luitjohan, F. Daniel

2008-01-01

226

Requirements for a rectifying antenna solar cell technology  

NASA Astrophysics Data System (ADS)

We propose the development of optically rectifying antennas (rectennas) as a technology to develop ultra-high efficiency solar cells that are compatible with large scale fabrication (self assembling) and low-cost (plastic) technologies. We size the field enhancement factor that is needed to reach high efficiencies and we propose solutions for its implementation.

Nunzi, J. M.

2010-04-01

227

Investigation into receiving-rectifying elements of EHF rectennas  

Microsoft Academic Search

An approximate model for calculating the efficiency of receiving-rectifying elements (RRE) of large aperture rectennas for EHF and DMF bands is offered. The estimate of RRE potentialities was performed on the basis of the developed model. Rectennas with an operating frequency of 35 GHz, whose radiating structure was performed on the basis of the net structure formed with crossing of

M. A. Omarov; D. V. Gretskih; D. V. Sukhomlinov

2003-01-01

228

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

229

A new way of separating azeotropic mixtures in batch rectifier  

Microsoft Academic Search

Separation of a maximum boiling azeotrope (chloroform \\/ ethyl acetate) with intermediate boiling entrainer (2-chlorobutane) in batch rectifier is studied in this paper with a new configuration variant (IBED) of batch extractive distillation (BED). Feasibility study is performed, then the two configurations are compared on the basis of theoretical considerations, short-cut estimations, and rigorous simulations. More than 20 % of

C. Steger; Z. Lelkes; E. Rev; M. Meyer; Z. Fonyo

2004-01-01

230

Exploiting silicon chip technology for control of electrons on superfluid helium  

NASA Astrophysics Data System (ADS)

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

Bradbury, F. R.; Takita, Maika; Eng, Kevin; Gurrieri, T. M.; Wilkel, K. J.; Lyon, S. A.

2010-03-01

231

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

PubMed

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

2013-10-07

232

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

SciTech Connect

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

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

2010-03-01

233

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

234

Methods for controlling the pore properties of ultra-thin nanocrystalline silicon membranes  

NASA Astrophysics Data System (ADS)

Porous nanocrystalline silicon (pnc-Si) membranes are a new class of solid-state ultra-thin membranes with promising applications ranging from biological separations to use as a platform for electron imaging and spectroscopy. Because the thickness of the membrane is only 15-30 nm, on the order of that of the molecules to be separated, mass transport through the membrane is greatly enhanced. For applications involving molecular separations, it is crucial that the membrane is highly permeable to some species while being nearly impermeable to others. An important approach to adjusting the permeability of a membrane is by changing the size and density of the pores. With pnc-Si, a rapid thermal treatment is used to induce nanopore formation in a thin film of nanocrystalline silicon, which is then released over a silicon scaffold using an anisotropic etchant. In this study, we examine the influence of thin film deposition and thermal treatment parameters on pore size and density.

Fang, D. Z.; Striemer, C. C.; Gaborski, T. R.; McGrath, J. L.; Fauchet, P. M.

2010-11-01

235

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.

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

2013-01-01

236

Detection of ferromagnetic resonance in a single-crystalline Fe wire using a rectifying effect  

NASA Astrophysics Data System (ADS)

The broadband ferromagnetic resonance (FMR) of a single-crystalline Fe microwire was measured using a rectifying effect. The experimental result indicates the uniform mode dominates the system. The effective Gilbert damping factor of the Fe wire was estimated by the rectifying effect. A rectifying spectrum is broadened because of the spin wave excitation and the thermal fluctuation as the input power increases.

Kasatani, Y.; Yamaguchi, A.; Miyajima, H.; Nozaki, Y.

2011-01-01

237

Junction barrier Schottky rectifier with an improved P-well region  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

238

A comparison of piezoelectric transformer AC\\/DC converters with current doubler and voltage doubler rectifiers  

Microsoft Academic Search

The objective of this study was to develop recommendations for an optimal design of piezoelectric transformer (PT) AC\\/DC converters. The paper presents a comprehensive comparison of the two commonly used rectifier topologies in a PT based power converters: current doubler and voltage doubler rectifiers. The advantages and disadvantages of the two rectifiers were investigated and the range of their applications

Gregory Ivensky; Svetlana Bronstein; S. Ben-Yaakov

2004-01-01

239

Megawatt wind energy conversion system with diode rectifier and multilevel current source inverter  

Microsoft Academic Search

This paper proposes the topology of diode rectifier plus multilevel current source inverter for synchronous gene- rator based direct-drive megawatt wind energy conversion systems. On the generator side, the diode rectifier is employed for cost reduction. Assuming the grid-side converter is a pulse- width modulated (PWM) current source inverter (CSI), ana- lyses on feasibility of using the diode rectifier and

Jiacheng Wang; Jingya Dai; Bin Wu; Dewei Xu; Navid R. Zargari

2011-01-01

240

A High Power Density Single-Phase PWM Rectifier with Active Ripple Energy Storage  

SciTech Connect

It is well known that there exist second-order harmonic current and corresponding ripple voltage on dc bus for single phase PWM rectifiers. The low frequency harmonic current is normally filtered using a bulk capacitor in the bus which results in low power density. This paper proposed an active ripple energy storage method that can effectively reduce the energy storage capacitance. The feed-forward control method and design considerations are provided. Simulation and 15 kW experimental results are provided for verification purposes.

Ning, Puqi [ORNL; Wang, Ruxi [Virginia Polytechnic Institute and State University (Virginia Tech); Wang, Fei [ORNL; Boroyevich, Dushan [Virginia Polytechnic Institute and State University (Virginia Tech)

2010-01-01

241

Voltage-Doubler Rectifier with Sinusoidal Input Current Using Pump Circuits  

NASA Astrophysics Data System (ADS)

A single-phase voltage-doubler rectifier using pump circuits is presented. This can be operated in the switching states for pumping action to pump twice the peak supply voltage onto the output capacitor and for forcing the input current to follow its sinusoidal reference in the vicinity of a zero crossing of the supply. The arrangement tested, using two dual-switch power modules with IGBTs and a controller for output voltage regulation, is implemented to investigate the operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor under the output voltage duplication.

Kiyotake, Hirofumi; Okada, Hidehiko; Ishizaka, Kouichi; Itoh, Ryozo

242

Single-Phase Voltage-Quadrupler Rectifier Reducing Input Current Distortion  

NASA Astrophysics Data System (ADS)

A single-phase voltage-quadrupler rectifier with reduced input current distortion is presented. This can be operated in the switching states for pumping action to pump twice the peak supply voltage onto each of the output capacitors and for forcing the input current to follow its sinusoidal reference in the vicinity of a zero crossing of the supply. The experimental prototype, using two dual-switch power modules with IGBTs and a controller for output voltage regulation, is implemented to investigate the operation. The experimental results confirm that the input current can be waveshaped sinusoidally with a near-unity power factor.

Itoh, Ryozo; Ishizaka, Kouichi; Neba, Yasuhiko; Hirata, Yuki

243

Silicon Wafer Lapping  

NSDL National Science Digital Library

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

2010-02-08

244

Using FPGA for visuo-motor control with a silicon retina and a humanoid robot  

Microsoft Academic Search

The address-event representation (AER) is a neuromorphic communication protocol for transferring asynchronous events between VLSI chips. The event information is transferred using a high speed digital parallel bus. This paper present an experiment based on AER for visual sensing, processing and finally actuating a robot. The AER output of a silicon retina is processed by an AER filter implemented into

Alejandro Linares-barranco; F. Gomez-rodriguez; Angel Jiménez-fernandez; Tobi Delbrück; P. Lichtensteiner

2007-01-01

245

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

Microsoft Academic Search

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

Abdullah Moinuddin; Jony C. Sarker; Akhter Zia

2012-01-01

246

Bistable silicon microvalve with thermoelectrically driven thermopneumatic actuator for liquid flow control  

Microsoft Academic Search

This paper presents a bistable microfluidic valve with a thermopneumatic actuator that is thermoelectrically driven. A functional prototype is fabricated in silicon technology. The majority of the fabrication process, including the integration of the micro-Peltier devices, is performed at wafer level. The tested valves are switched with ±10 V pulses with an energy input of approximately 1 J for closing

Till Huesgen; Gabriel Lenk; Thomas Lemke; Peter Woias

2010-01-01

247

Effect of controlled oxidation processes on the emission and excitation of porous silicon  

NASA Astrophysics Data System (ADS)

The strong luminescence activity of porous silicon prepared by anodization of silicon in HF is a remarkable phenomenon, considering the fact that ordinary crystalline silicon is not at all an efficient light emitter due to the indirect character of its bandgap. In spite of the intense theoretical and experimental activity, the basic mechanism responsible for this efficient luminescence is still under debate. Nevertheless, there is a growing concensus that quantum confinement in nanocrystallites is an important element of this mechanism. However, there are two competing models, both based on quantum confinement, namely bulk-like radiative recombination and novel radiative surface state recombination. In small crystallites the number of surface atoms is a sizeable fraction of the total and therefore surface conditions (both type and quality) are expected to play an important role. We have performed time-resolved emission in the musec regime and excitation measurements of porous silicon and studied the quantum efficiency under various surface oxidation treatments. We have found that, although the overall quantum efficiency (and hence the brightness of the porous surface) can vary a lot as a function of surface conditions, the time behavior of the luminescence is only weakly affected by these conditions. This leads to the conclusion that the emitting states are pretty much unaffected by the various surface treatments and consequently we believe that most likely one or both of the radiatively recombining carriers are localized.

Rigakis, Nikolaos

248

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

Microsoft Academic Search

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

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

2011-01-01

249

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

250

A 12 kW three-phase low THD rectifier with high-frequency isolation and regulated DC output  

Microsoft Academic Search

A robust 12 kW rectifier with low THD in the line currents, based on an 18-pulse transformer arrangement with reduced kVA capacities followed by a high-frequency isolation stage is presented in this work. Three full-bridge (buck-based) converters are used to allow galvanic isolation and to balance the dc-link currents, without current sensing or current controller. The topology provides a regulated

F. J. M. de Seixas; I. Barbi

2004-01-01

251

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Confers Glibenclamide Sensitivity to Outwardly Rectifying Chloride Channel (ORCC) in Hi5 Insect Cells  

Microsoft Academic Search

.   Increasing evidence is now accumulating for the involvement of the cystic fibrosis transmembrane conductance regulator (CFTR)\\u000a in the control of the outwardly rectifying chloride channel (ORCC). We have examined the sensitivity of ORCC to the sulfonylurea\\u000a drug glibenclamide in Hi-5 (Trichoplusia ni) insect cells infected with recombinant baculovirus expressing either wild-type CFTR, ?F508-CFTR or E. coli? galactosidase cDNA and

M. Julien; B. Verrier; M. Cerutti; V. Chappe; M. Gola; G. Devauchelle; F. Becq

1999-01-01

252

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

253

Identification of G Protein-Coupled, Inward Rectifier Potassium Channel Gene Products from the Rat Anterior Pituitary Gland  

Microsoft Academic Search

Dopamine (DA) is a physiological regulator of PRL secretion, ex- erting tonic inhibitory control. DA activates an inward rectifier K1 (IRK) channel in rat lactotropes, causing membrane hyperpolariza- tion and inhibition of Ca21-dependent action potentials. Both the activation of this effector K1 channel and the inhibition of PRL release are mediated by D2-type receptor activation and pertussis toxin- sensitive G

KAREN A. GREGERSON; THOMAS P. FLAGG; THOMAS J. O'NEILL; MARK ANDERSON; OANH LAURING; JILL S. HOREL; PAUL A. WELLING

2001-01-01

254

An unity high power factor power supply rectifier using a PWM AC\\/DC full bridge soft-switching  

Microsoft Academic Search

This paper proposes an improvement of an isolated unity-power-factor rectifier AC\\/DC PWM based on a PWM full bridge converter using a commutation cell. This converter operates using soft switching technique. It presents high power factor, full control of the output dc voltage and high-frequency line filter inductor and insulation transformer. It is based in an auxiliary voltage source that feeds

C. A. Gallo; J. A. Correa Pinto; L. C. de Freitas; V. J. Farias; E. A. A. Coelho

2002-01-01

255

Grafting control of mainstay terpyridine self-assembled monolayers for the preparation of planar silicon surfaces with variable catalytic loadings.  

PubMed

Monolayers of terpyridine-derivatized silanes were self-assembled, with accurately controlled grafting densities, on single-crystal silicon surfaces. Complexation of the resulting terpyridine monolayers with Pd(OAc)(2) afforded a series of catalytic surfaces covering a full range of Pd loadings (0.14-0.85 nmol.cm(-2)) in the aim to explore their impact on catalysis methodically. X-ray reflectivity (XRR), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma mass spectrometry (ICP-MS) were combined to afford a precise picture of the grafting density, chemical composition, and catalyst loadings of the surfaces investigated here. We report that the control of the terpyridine density and thus the control of catalytic loadings can be achieved through a fine modification of silanization concentrations, which affords surfaces with tunable catalytic activity. PMID:23002697

Fernandes, Antony E; Devillez, Sébastien; d'Haese, Cécile; Deumer, Gladys; Haufroid, Vincent; Nysten, Bernard; Riant, Olivier; Jonas, Alain M

2012-10-03

256

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

257

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

258

CMOS-Based High-Density Silicon Microprobe Array for Electronic Depth Control in Neural Recording  

Microsoft Academic Search

This paper reports on a novel CMOS-based high-density silicon microprobe array for intracortical recording applications. In contrast to existing systems, CMOS multiplexing units are integrated on the slender, needle-like probe shaft 160 mum in width. In the present implementation an unequaled number of 188 electrodes (diameter 20 mum, pitch 40 mum) are arranged in two columns along the 4-mm-long probe

K. Seidl; S. Herwik; Y. Nurcahyo; T. Torfs; M. Keller; M. Schuttler; H. Neves; T. Stieglitz; O. Paul; P. Ruther

2009-01-01

259

Control factor of native oxide growth on silicon in air or in ultrapure water  

Microsoft Academic Search

Native silicon (Si) oxide growth on Si (100) wafers in air and in ultrapure water at room temperature requires coexistence of water and oxygen in the air and ultrapure water ambients. The growth rate data on n-, n+-, and p+-Si (100) in air indicate layer-by-layer growth of an oxide. The growth rate on n-Si (100) in ultrapure water may be

M. Morita; T. Ohmi; E. Hasegawa; M. Kawakami; K. Suma

1989-01-01

260

Insertion of intelligent hydrogel into silicone resin for thermal control applications  

Microsoft Academic Search

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

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

2009-01-01

261

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

262

Single mode heat rectifier: controlling energy flow between electronic conductors.  

PubMed

We study heat transfer between conductors, mediated by the excitation of a monomodal harmonic oscillator. Using a simple model, we show that the onset of rectification in the system is directly related to the nonlinearity of the electron gas dispersion relation. When the metals have a strictly linear dispersion relation, a Landauer-type expression for the thermal current holds, symmetric with respect to the temperature difference. Rectification becomes prominent when deviations from linear dispersion exist, and the fermionic model cannot be mapped into a harmonic bosonized representation. The effects described here are relevant for understanding radiative heat transfer and vibrational energy flow in electrically insulating molecular junctions. PMID:18352208

Segal, Dvira

2008-03-13

263

The Water-Cooled Steel-Tank Rectifier Corrosion Problem  

Microsoft Academic Search

The first mercury-are rectifiers utilized glass tubes and consequently the physical size and electrical capacity was limited. The efforts to increase the available output led to the development of water-cooled steel-tank vacuum chambers after many years of research and the solution of many problems. This paper is primarily concerned with the solution of the problem presented by corrosion. Corrosion is

Emil J. Remscheid

1941-01-01

264

Minimal Riesz energy point configurations for rectifiable d -dimensional manifolds  

Microsoft Academic Search

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

D. P. Hardin; E. B. Saff

2005-01-01

265

Novel compact synchronous rectifier with power factor correction  

Microsoft Academic Search

Sheppard-Taylor(S-T) topology was presented to reduce the output current ripple of DC-DC converters. In this paper, we modified the S-T circuit into AC-DC converter with functions of synchronous rectifier (SR) and power factor correction (PFC). Firstly, we made a comparison between several topologies to show the advantages of AC-DC S-T circuit for our design aim. Then we built up the

Zhao Liang; Zhang Bo; Ma Huasheng

2005-01-01

266

Rectified Momentum Transport for a Kicked Bose-Einstein Condensate  

Microsoft Academic Search

We report the experimental observation of rectified momentum transport for a Bose-Einstein condensate kicked at the Talbot time (quantum resonance) by an optical standing wave. Atoms are initially prepared in a superposition of the 0 and -2ℏkl momentum states using an optical pi\\/2 pulse. By changing the relative phase of the superposed states, a momentum current in either direction along

Mark Sadgrove; Munekazu Horikoshi; Tetsuo Sekimura; Ken'Ichi Nakagawa

2007-01-01

267

Reduced parts-count multi-level rectifiers  

Microsoft Academic Search

Multi-level power converters have gained much attention due to their high power quality, low switching losses, and high-voltage capability. These advantages make the multi-level converter a candidate topology for the next generation of naval ship propulsion systems. The primary disadvantage of these systems is the large number of semiconductors involved. This paper presents a reduced parts-count rectifier which is well

K. A. Corzine; J. R. Baker; J. Yuen

2001-01-01

268

Silicone metalization  

DOEpatents

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

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

2008-12-09

269

Rectified cell migration on saw-like micro-elastically patterned hydrogels with asymmetric gradient ratchet teeth.  

PubMed

To control cell motility is one of the essential technologies for biomedical engineering. To establish a methodology of the surface design of elastic substrate to control the long-range cell movements, here we report a sophisticated cell culture hydrogel with a micro-elastically patterned surface that allows long-range durotaxis. This hydrogel has a saw-like pattern with asymmetric gradient ratchet teeth, and rectifies random cell movements. Durotaxis only occurs at boundaries in which the gradient strength of elasticity is above a threshold level. Consequently, in gels with unit teeth patterns, durotaxis should only occur at the sides of the teeth in which the gradient strength of elasticity is above this threshold level. Therefore, such gels are expected to support the long-range biased movement of cells via a mechanism similar to the Feynman-Smoluchowski ratchet, i.e., rectified cell migration. The present study verifies this working hypothesis by using photolithographic microelasticity patterning of photocurable gelatin gels. Gels in which each teeth unit was 100-120 µm wide with a ratio of ascending:descending elasticity gradient of 1:2 and a peak elasticity of ca. 100 kPa supported the efficient rectified migration of 3T3 fibroblast cells. In addition, long-range cell migration was most efficient when soft lanes were introduced perpendicular to the saw-like patterns. This study demonstrates that asymmetric elasticity gradient patterning of cell culture gels is a versatile means of manipulating cell motility. PMID:24147112

Kidoaki, Satoru; Sakashita, Hiroyuki

2013-10-17

270

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

PubMed Central

To control cell motility is one of the essential technologies for biomedical engineering. To establish a methodology of the surface design of elastic substrate to control the long-range cell movements, here we report a sophisticated cell culture hydrogel with a micro-elastically patterned surface that allows long-range durotaxis. This hydrogel has a saw-like pattern with asymmetric gradient ratchet teeth, and rectifies random cell movements. Durotaxis only occurs at boundaries in which the gradient strength of elasticity is above a threshold level. Consequently, in gels with unit teeth patterns, durotaxis should only occur at the sides of the teeth in which the gradient strength of elasticity is above this threshold level. Therefore, such gels are expected to support the long-range biased movement of cells via a mechanism similar to the Feynman-Smoluchowski ratchet, i.e., rectified cell migration. The present study verifies this working hypothesis by using photolithographic microelasticity patterning of photocurable gelatin gels. Gels in which each teeth unit was 100–120 µm wide with a ratio of ascending:descending elasticity gradient of 1:2 and a peak elasticity of ca. 100 kPa supported the efficient rectified migration of 3T3 fibroblast cells. In addition, long-range cell migration was most efficient when soft lanes were introduced perpendicular to the saw-like patterns. This study demonstrates that asymmetric elasticity gradient patterning of cell culture gels is a versatile means of manipulating cell motility.

Kidoaki, Satoru; Sakashita, Hiroyuki

2013-01-01

271

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; Onar, Omer C [ORNL; Miller, John M [ORNL; Tang, Lixin [ORNL

2013-01-01

272

On the metallurgical control of texture sharpness and related magnetic properties in grain-oriented silicon-iron  

NASA Astrophysics Data System (ADS)

The final Goss texture sharpness and the related magnetic behaviour of a grain-oriented silicon-iron sheet is, in the end, controlled by its primary recrystallization texture at final thickness. In spite of the general idea that attributes the final Goss texture sharpness control to the precision of the Goss nuclei present at that stage, it is becoming clear that the main metallurgical role is played instead by the Goss nuclei surrounding texture. This texture selects the secondary recrystallization (SR) grains in a specific Goss-oriented spread range by a mechanism comparable, in principle, to the `lock-and-key' enzymatic selective catalysis mechanism, well known in biochemistry. The microstructure and magnetic behaviour differences between conventional grain-oriented (CGO) and super-oriented (HiB) sheets, as well as between various final sheet thickness products, are explained in this framework.

Fortunati, S.

1994-05-01

273

Controlling growth and field emission property of aligned carbon nanotubes on porous silicon substrates  

NASA Astrophysics Data System (ADS)

An aligned and well-distributed carbon nanotubes array was produced by pyrolysis of hydrocarbons catalyzed by nickel nanoparticles embedded in porous silicon (PS) substrates. Scanning electron microscope images show that the nanotubes form an aligned array approximately perpendicular to the surface of the PS substrate and the diameters of most of the tubes within the array are 10-30 nm. High-magnification transmission electron microscopy images confirmed that the nanotubes are well graphitized and typically consist of about 15 concentric shells of carbon sheets. Furthermore, the strong field emission from the aligned carbon nanotubes emitter by pyrolysis of hydrocarbons was observed.

Xu, Dongsheng; Guo, Guolin; Gui, Linlin; Tang, Youqi; Shi, Zujin; Jin, Zhaoxia; Gu, Zhennan; Liu, Weimin; Li, Xiulan; Zhang, Guanghua

1999-07-01

274

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

2013-05-03

275

Control of Electrostatic Coupling Observed for Silicon Double Quantum Dot Structures  

NASA Astrophysics Data System (ADS)

We study the electrostatic coupling in the silicon double quantum dot (DQD) structure as a key building block for a charge-based quantum computer and a quantum cellular automaton (QCA). We realize the three interdot coupling regimes of the DQD structure only by optimizing the DQD design and the thermal oxidation condition. We then demonstrate that the electrostatic coupling between DQDs can be modulated by tuning the negative voltage of the side gate electrode. Note that the interdot coupling was largely modulated with a small decrease in the gate voltage from 0 to -100 mV because our structure initially has the DQD geometry. Furthermore, the device fabrication is compatible with the conventional silicon complementary metal-oxide-semiconductor (CMOS) process. This structure is suitable for the future integration of CMOS devices. In addition, we show the derivation of the DQDs’ capacitances, including the gate cross capacitances, as a function of the spacing between the two adjacent charge triple points. By using these capacitances, the electron transport properties of the DQD structure are simulated, and the modulation of the electrostatic coupling is successfully simulated as the change of the total capacitance in DQDs.

Yamahata, Gento; Tsuchiya, Yoshishige; Oda, Shunri; Durrani, Zahid A. K.; Mizuta, Hiroshi

2008-06-01

276

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

277

A hybrid driving scheme for full-bridge synchronous rectified LLC resonant DC\\/DC converter  

Microsoft Academic Search

A novel hybrid driving scheme for full-bridge synchronous rectified LLC resonant DC\\/DC converter is proposed in this paper. With the full-bridge type rectifier, the voltage stress of the synchronous rectifiers (SRs) is well clamped to the output voltage. Also the transformer structure is very simple due to only one secondary winding is needed. Therefore, the converter can utilize SRs with

Xiucheng Huang; Jianfeng Wang; Junming Zhang; Zhaoming Qian

2011-01-01

278

Rectifying and perfect spin filtering behavior realized by tailoring graphene nanoribbons  

NASA Astrophysics Data System (ADS)

An armchair graphene nanoribbon based electronic device with spin filtering and rectifying behavior is designed by means of molecular tailoring, and the electronic transport properties are calculated by using nonequilibrium Green's functions in combination with the density functional theory. The results show that the rectifying behavior can be observed in the junctions, and the rectifying ratio can be effectively tuned by edge doping. Furthermore, perfect spin polarization behavior can also be observed in the junctions.

He, Jun; Chen, Ke-Qiu

2012-12-01

279

Regenerative drive converter with line-frequency switched rectifier and without DC link components  

Microsoft Academic Search

The presented regenerative drive converter consists of a line-side three-phase rectifier and a motor-side three-phase inverter. Antiparallel to the rectifier diodes there are six IGBTs, which conduct the DC link current, if it flows from the inverter to the rectifier. In the DC link there are no components: neither an inductor or an electrolytic capacitor nor a braking resistor or

Bemhard Piepenbreier; Lothar Sack

2004-01-01

280

High-density bidirectional rectifier for next generation 380-V DC distribution system  

Microsoft Academic Search

A high-density bidirectional rectifier was developed not only for telecom and data center applications but also for next generation 380-V DC distribution systems. A conventional rectifier consists of an AC 200-V\\/DC 380-V power factor correction (PFC) converter and an isolated DC 380-V\\/DC 380-V converter, and the power flow is unidirectional. Two approaches are proposed for creating a high-density bidirectional rectifier

Yusuke Hahashi; Masato Mino

2012-01-01

281

Small-signal modeling of multipulse rectifiers for more-electric aircraft applications  

Microsoft Academic Search

This paper presents small-signal input impedance models for multipulse rectifiers that are widely used on next-generation more-electric aircraft (MEA). The basic modeling method is a generalization of the impedance mapping method that has been previously applied to single- phase and three-phase six-pulse rectifiers. Mapping functions are first defined for general TV-phase rectifiers and used to calculate their input impedances by

Jian Sun; Zhonghui Bing; Kamiar J. Karimi

2008-01-01

282

Nuclear magnetic resonance linewidth and spin diffusion in {sup 29}Si isotopically controlled silicon  

SciTech Connect

A nuclear magnetic resonance (NMR) study was performed with n-type silicon single crystals containing {sup 29}Si isotope abundance f ranges from 1.2% to 99.2%. The nuclear spin diffusion coefficient D has been determined from the linewidth of significantly enhanced {sup 29}Si NMR signals utilizing a developed dynamic nuclear polarization (DNP) method. The {sup 29}Si NMR linewidth depends linearly on f, at least when f<10%, and approaches {proportional_to}f{sup 1/2} dependence when f>50%. The estimated {sup 29}Si nuclear spin diffusion time T{sub sd} between phosphorus atoms used for DNP is more than ten times shorter than the nuclear polarization time T{sub 1}{sup p} of {sup 29}Si nuclei around phosphorus. Therefore, the regime of 'rapid spin diffusion' is realized in the DNP experiments.

Hayashi, Hiroshi; Itoh, Kohei M.; Vlasenko, Leonid S. [Department of Applied Physics and Physico-Informatics, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); A. F. Ioffe Physico-Technical Institute, 194021 Saint Petersburg (Russian Federation)

2008-10-15

283

Novel mini-reactor of silicone oil droplets for synthesis of morphology-controlled polymer particles.  

PubMed

Inside spaces of emulsion droplets can be used as mini-reactors for material synthesis. The novel application of sol-gel derived silicone oil droplets as mini-reactors was examined for the case of polymerization of styrene (St) and comonomers with the oil-soluble initiator 2,2'-azobis(2,4-dimethylvaleronitrile). Polydimethylsiloxane (PDMS) droplets prepared from dimethylsiloxane were used as the mini-reactors, in which the polymerization of St without comonomers was first conducted. In the polymerization, the St/PDMS volume ratio was varied from 0.025 to 0.10. After the polymerization, each PDMS droplet contained a polystyrene (PSt) particle. The St/PDMS ratio of 0.05 enabled the synthesis of micrometer-sized, spherical PSt particles with low polydispsersity. Copolymerization of St with comonomers having hydrophilic groups deformed the spherical shape of particles to lens-like or disk-like morphologies that were obtained with acrylic acid or sodium 4-styrene sulfonate, respectively. In another copolymerization, with divinylbenzene used as a cross-linker, hemispherical polymer particles were formed. To diversify the particle morphologies further, the proposed mini-reactor synthesis was combined with the recently proposed silicone oil droplet templating method (Ohta et al., 2012). Around the PDMS droplets containing a polymer particle, polymeric shells with a depression were successfully formed with the proposed method. The remaining PDMS oil inside the polymeric shells was extracted with ethanol, which caused hemispherical polymeric bowl-shaped capsules having a protrusion on the inside. PMID:23194249

Nagao, Daisuke; Ohta, Tatsuya; Ishii, Haruyuki; Imhof, Arnout; Konno, Mikio

2012-12-10

284

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

NASA Astrophysics Data System (ADS)

The fractionation of silicon (Si) stable isotopes by biological activity in the surface ocean makes the stable isotope composition of silicon (?30Si) dissolved in seawater a sensitive tracer of the oceanic biogeochemical Si cycle. We present a high-precision dataset that characterizes the ?30Si distribution in the deep Atlantic Ocean from Denmark Strait to Drake Passage, documenting strong meridional and smaller, but resolvable, vertical ?30Si gradients. We show that these gradients are related to the two sources of deep and bottom waters in the Atlantic Ocean: waters of North Atlantic and Nordic origin carry a high ?30Si signature of ?+1.7‰ into the deep Atlantic, while Antarctic Bottom Water transports Si with a low ?30Si value of around +1.2‰. The deep Atlantic ?30Si distribution is thus governed by the quasi-conservative mixing of Si from these two isotopically distinct sources. This disparity in Si isotope composition between the North Atlantic and Southern Ocean is in marked contrast to the homogeneity of the stable nitrogen isotope composition of deep ocean nitrate (?15N-NO3). We infer that the meridional ?30Si gradient derives from the transport of the high ?30Si signature of Southern Ocean intermediate/mode waters into the North Atlantic by the upper return path of the meridional overturning circulation (MOC). The basin-scale deep Atlantic ?30Si gradient thus owes its existence to the interaction of the physical circulation with biological nutrient uptake at high southern latitudes, which fractionates Si isotopes between the abyssal and intermediate/mode waters formed in the Southern Ocean.

Souza, Gregory F.; Reynolds, Ben C.; Rickli, JöRg; Frank, Martin; Saito, Mak A.; Gerringa, Loes J. A.; Bourdon, Bernard

2012-06-01

285

Nanoscale lateral switchable rectifiers fabricated by local anodic oxidation  

NASA Astrophysics Data System (ADS)

Scanning probe lithography as a mean to pattern, implement, and discover new devices in different materials systems provides an elevated degree of flexibility, permitting one to tailor device geometries and structures at will, in particular by virtue of modification of the local chemistry. Here we define metal-insulator-metal junctions exhibiting a switchable rectifier behavior by patterning titanium channels through local anodic oxidation techniques. The nanoscale TiO2 junctions thus formed exhibit IV characteristics with non-volatile switchable rectification and memristive behavior due to ionic motion through the metal-semiconductor interfaces.

Siles, Pablo F.; Archanjo, B. S.; Baptista, D. L.; Pimentel, V. L.; Joshua, J.; Neves, B. R. A.; Medeiros-Ribeiro, G.

2011-07-01

286

Rectifying property and magnetoresistance of manganite–stannate junctions  

NASA Astrophysics Data System (ADS)

By employing the perovskite-structured stannates and manganites, p-La0.67Ca0.33MnO3/i-SrSnO3/n-La0.03Sr0.97SnO3 junctions were fabricated on SrTiO3(001) substrates by pulsed laser deposition technique. The current–voltage curves indicate an excellent rectifying property of the heterojunction in the measurement temperatures from 310 to 10 K. A crossover from negative to positive of magnetoresistance with bias voltage was observed, which was explained by the transport mechanism of diffused electrons.

Liu, Qinzhuang; Li, Hong; Li, Bing; Liu, Qiangchun; Zhu, Guangping; Dai, Kai; Liu, Zhongliang; Liu, Jianjun; Dai, Jianming

2013-11-01

287

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

288

Design, performance, and application of a new bipolar synchronous rectifier  

NASA Astrophysics Data System (ADS)

A bipolar transistor which is specifically designed for synchronous rectifier applications is described with emphasis placed on its design and performance. It is shown that as opposed to conventional devices such as the Schottky, the proposed transistor has an emitter-base voltage exceeding 50 V, which in effect allows for first and third quadrant blocking. Moreover, this feature enables the transistor to be used in a pulse width modulation mode where both regulation and rectification can be achieved in the power supply secondary. A novel base drive circuit is employed which results in only a minor increase in complexity, but allows for operation at switching frequencies up to 250 kHz.

Hower, P. L.; Kepler, G. M.; Patel, R.

289

Real-time monitoring and process control in amorphous/crystalline silicon heterojunction solar cells by spectroscopic ellipsometry and infrared spectroscopy  

NASA Astrophysics Data System (ADS)

In amorphous/crystalline silicon heterojunction solar cells, we have performed real-time thickness control of hydrogenated amorphous silicon (a-Si:H) layers with a precision better than +/-1 A? by applying spectroscopic ellipsometry (SE). A heterojunction solar cell fabricated by this process shows a relatively high conversion efficiency of 14.5%. At the amorphous/crystalline interface, however, infrared attenuated total reflection spectroscopy (ATR) revealed the formation of a porous a-Si:H layer with a large SiH2-hydrogen content of 27 at. %. Based on SE and ATR results, we discuss the growth processes and structures of a-Si:H in heterojunction solar cells.

Fujiwara, Hiroyuki; Kondo, Michio

2005-01-01

290

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

291

A novel solid-state thermal rectifier based on reduced graphene oxide.  

PubMed

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

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

2012-07-23

292

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

293

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

PubMed Central

G protein-gated inwardly rectifying potassium (GIRK) channels hyperpolarize neurons in response to the activation of many 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 their subunit composition. Pharmacological investigations of GIRK channels and studies in animal models suggest that GIRK activity has an important role in physiological responses, including pain perception and memory modulation. Moreover, abnormal GIRK function has been implicated in altering neuronal excitability and cell death that may be important in the pathophysiology of human diseases such as epilepsy, Down’s syndrome, Parkinson’s disease and drug addiction. GIRK channels may therefore prove to be a valuable new therapeutic target for treating these health problems.

Luscher, Christian; Slesinger, Paul A.

2010-01-01

294

Porosity control in metal-assisted chemical etching of degenerately doped silicon nanowires.  

PubMed

We report the fabrication of degenerately doped silicon (Si) nanowires of different aspect ratios using a simple, low-cost and effective technique that involves metal-assisted chemical etching (MacEtch) combined with soft lithography or thermal dewetting metal patterning. We demonstrate sub-micron diameter Si nanowire arrays with aspect ratios as high as 180:1, and present the challenges in producing solid nanowires using MacEtch as the doping level increases in both p- and n-type Si. We report a systematic reduction in the porosity of these nanowires by adjusting the etching solution composition and temperature. We found that the porosity decreases from top to bottom along the axial direction and increases with etching time. With a MacEtch solution that has a high [HF]:[H(2)O(2)] ratio and low temperature, it is possible to form completely solid nanowires with aspect ratios of less than approximately 10:1. However, further etching to produce longer wires renders the top portion of the nanowires porous. PMID:22781120

Balasundaram, Karthik; Sadhu, Jyothi S; Shin, Jae Cheol; Azeredo, Bruno; Chanda, Debashis; Malik, Mohammad; Hsu, Keng; Rogers, John A; Ferreira, Placid; Sinha, Sanjiv; Li, Xiuling

2012-07-10

295

Control of Parameters Influencing the Thermal Imprint of Parylene/Silicon  

NASA Astrophysics Data System (ADS)

The study aims to investigate the possible defects that may occur during imprinting of poly(chloro- p-xylylene) (parylene-C) film (thermal oxidation, delamination, thermal cracking and insufficient filling at the periphery) and to overcome them by modifying the process conditions and mold design. X-ray diffraction (XRD) analyses results for the parylene-C films indicated that higher deposition pressure leads to a lower crystallinity of parylene-C film. By tuning the process conditions and mold design, patterned fields (composed of arrays of 25-?m-high, 10-?m-wide and 1-mm-long lines with 10 ?m spacing) in 0.4-mm-thick and 20-mm-sized nickel molds could be successfully replicated on 60-?m-thick parylene-C films deposited at both 25 and 45 mTorr. Complete filling over the whole imprint area could be achieved at <270 °C with the press force at 2 kN and the press hold time of 900 s with the aid of an implemented dummy pattern. Both thermal cracking and delamination could be avoided, even at 270 °C, under the established process conditions and mold design with the help of an adhesion promotion treatment of silicon substrates (SF6 plasma etching for 2 min and spin-coating of KBM-503-based solution). Furthermore, the molds used for paryelne imprinting could be cleaned by dipping in chloronaphthalene solution at >175 °C, followed by an oxygen plasma etching.

Youn, Sung-Won; Goto, Hiroshi; Oyama, Shoji; Takahashi, Masaharu; Maeda, Ryutaro

2007-09-01

296

Characteristics of Delayed Rectifier Potassium Channels Exposed to 3 mT Static Magnetic Field  

Microsoft Academic Search

To investigate the characteristics of delayed rectifier potassium channel of cells under moderate intensity static magnetic field, the delayed rectifier potassium channel currents (IK) of acutely isolated mouse prefrontal cortex pyramidal neurons were examined. IK was measured and recorded after the neurons were exposed to 3 mT static magnetic field for 15,30, and 60 min. The results demonstrated that the

Gang Li; Lijun Cheng; Xiaoyan Qiao; Ling Lin

2010-01-01

297

A rectifying and refining algorithm of vascular mesh in 3D model  

Microsoft Academic Search

To simulate the benign tumor growth in complex vascular environment accurately, the shape of blood vessels should be coordinated with the truth and, therefore, the mesh of geometric model constructed from the pictures of cut corpse should be rectified and refined. A strategy of rectifying vascular mesh is presented in this paper. In the method, some vertices will move along

Gan Jian-Hong; Dai Pei-Dong; Qiang Peng; Jim X. Chen; Zhang Tian-Yu; Wang Zheng-Min

2008-01-01

298

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

299

Invariant rectifying-stripping curves for targeting minimum energy and feed location in distillation  

Microsoft Academic Search

Invariant rectifying-stripping (IRS) curves are proposed that are independent of the feed location and operating reflux of the distillation column for a given separation problem. IRS curves represent the enthalpy surpluses and deficits in the rectifying and stripping sections, respectively, as a function of temperature for all possible values of reflux and reboil. The IRS curves provide a new representation

Santanu Bandyopadhyay; Ranjan K. Malik; Uday V. Shenoy

1999-01-01

300

Design and implementation of a novel synchronous-rectifier forward converter with improved performance  

Microsoft Academic Search

This article proposes two new methods for improving the performance of a synchronous-rectifier forward converter. A synchronous-rectifier converter produces a reverse current in the inductor due to the bidirectional characteristic of MOSFETs while the converter is turned off. This reverse current causes voltage spikes which may damage the power devices. This article proposes two methods to reduce the voltage spikes:

Tian-Hua Liu; Kuan-Sheng Wang

2010-01-01

301

Regulation of the cardiac delayed rectifier K current by neurotransmitters and magnesium  

Microsoft Academic Search

Summary The delayed rectifier K current plays an important role in cardiac electrophysiology: It is involved in the repolarization of the action potential and in frequency-dependent changes in action potential duration and waveform. The delayed rectifier current IK is regulated by the autonomic nervous system: Beta-adrenergic agonists increase IK. This increase is due to an increase in the maximally activatable

H. Criss Hartzell; Isabelle Duchatelle-Gourdon

1993-01-01

302

Determination of the subunit stoichiometry of an inwardly rectifying potassium channel  

Microsoft Academic Search

Inwardly rectifying K+ channels are distantly related to their voltage-gated counterparts and possess a structural motif of only two putative transmembrane segments in each subunit. They are formed by the assembly of an unknown number of subunits. We have examined the subunit stolchiometry of a strongly rectifying K+ channel, IRK1, by linking together the coding sequence of three or four

Jian Yang; Yuh Nung Jan; Lily Yeh Jan

1995-01-01

303

Self-rectifying electron beam melter for pendant-drop containerless processing  

Microsoft Academic Search

A self-rectifying electron beam melting technique is described. Utilizing an ac power supply, in contrast to the more usual dc supply, the in situ self-rectifying approach offers a simple and very inexpensive means of producing metallic pendant drops for use in containerless melt-processing experiments.

D. S. Pyun; E. W. Collings

1993-01-01

304

Self-rectifying electron beam melter for pendant-drop containerless processing  

Microsoft Academic Search

A self-rectifying electron beam melting technique is described. Utilizing an ac power supply, in contrast to the more usual dc supply, the insitu self-rectifying approach offers a simple and very inexpensive means of producing metallic pendant drops for use in containerless melt-processing experiments.

D. S. Pyun; E. W. Collings

1993-01-01

305

A MOSFET resonant synchronous rectifier for high-frequency DC\\/DC converters  

Microsoft Academic Search

A resonant synchronous rectifier which combines the fast switching of Schottky diodes with low conduction drop of MOSFET devices is discussed. The MOSFET devices are driven in a resonant fashion by the power circuit, resulting in partial recovery of the energy stored in the parasitic capacitances. Power loss in the resonant synchronous rectifier is determined as a function of various

Wojciech A. Tabisz; Fred C. Lee; Dan Y. Chen

1990-01-01

306

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

PubMed

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

Lynch, C

1985-11-01

307

Ultrafast active control of localized surface plasmon resonances in silicon bowtie antennas.  

PubMed

Localized surface plasmon polaritons (LSPPs) provide an efficient means of achieving extreme light concentration. In recent years, their active control has become a major aspiration of plasmonic research. Here, we demonstrate direct control of semiconductor bowtie antennas, enabling active excitation of LSPPs, at terahertz (THz) frequencies. We modify the LSPPs by ultrafast optical modulation of the free carrier density in the plasmonic structure itself, allowing for active control of the semiconductor antennas on picosecond timescales. Moreover, this control enables the manipulation of the field intensity enhancements in ranges of four orders of magnitude. PMID:21164664

Berrier, Audrey; Ulbricht, Ronald; Bonn, Mischa; Rivas, Jaime Gómez

2010-10-25

308

Controlled synthesis of millimeter-long silicon nanowires with uniform electronic properties.  

PubMed

We report the nanocluster-catalyzed growth of ultralong and highly uniform single-crystalline silicon nanowires (SiNWs) with millimeter-scale lengths and aspect ratios up to approximately 100,000. The average SiNW growth rate using disilane (Si 2H 6) at 400 degrees C was 31 microm/min, while the growth rate determined for silane (SiH 4) reactant under similar growth conditions was 130 times lower. Transmission electron microscopy studies of millimeter-long SiNWs with diameters of 20-80 nm show that the nanowires grow preferentially along the 110 direction independent of diameter. In addition, ultralong SiNWs were used as building blocks to fabricate one-dimensional arrays of field-effect transistors (FETs) consisting of approximately 100 independent devices per nanowire. Significantly, electrical transport measurements demonstrated that the millimeter-long SiNWs had uniform electrical properties along the entire length of wires, and each device can behave as a reliable FET with an on-state current, threshold voltage, and transconductance values (average +/-1 standard deviation) of 1.8 +/- 0.3 microA, 6.0 +/- 1.1 V, 210 +/- 60 nS, respectively. Electronically uniform millimeter-long SiNWs were also functionalized with monoclonal antibody receptors and used to demonstrate multiplexed detection of cancer marker proteins with a single nanowire. The synthesis of structurally and electronically uniform ultralong SiNWs may open up new opportunities for integrated nanoelectronics and could serve as unique building blocks linking integrated structures from the nanometer through millimeter length scales. PMID:18710294

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

2008-08-19

309

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

310

Analysis of Class E low di/dt rectifier with a series inductor  

NASA Astrophysics Data System (ADS)

An analysis along with an experimental verification is presented for a Class E zero-current-switching (low di/dt) rectifier. The circuit consists of a rectifier diode, an inductor connected in series with a diode, and a filter capacitor. The addition of the series inductor allows the rectifier to decouple the diode ON duty cycle and the output ripple voltage. The series inductor sets the value of the diode ON duty cycle which can be large, e.g., 0.5. The filter capacitor independently sets the level of the ripple voltage. The rectifier diode turns on at zero di/dt and low dv/dt and turns off at low /di/dt/, reducing switching losses, switching noise, and reverse-recovery current. The experimental results confirmed theoretical predictions. Other topologies of unregulated and regulated synchronous rectifiers are also discussed.

Kazimierczuk, Marian K.; Szaraniec, Wojciech

1993-01-01

311

Analysis and Design of a Modular Three-Phase AC-to-DC Converter Using CUK Rectifier Module With Nearly Unity Power Factor and Fast Dynamic Response  

Microsoft Academic Search

In this paper, the analysis and design of a modular three-phase AC-to-DC converter using single-phase isolated Cuk rectifier modules is discussed based on power balance control technique. This paper analyzes the operation of a modular converter as continuous-conduction-mode power factor correction (CCM-PFC). Design equations, as well as an average small-signal model of the proposed system to aid the control loop

Uthen Kamnarn; Viboon Chunkag

2009-01-01

312

Size controlled growth of silica nanowires by thermal decomposition of thin gold films on silicon  

Microsoft Academic Search

Control over nanowire growth is an important requirement for future nanotechnology devices because the physical structure and chemical properties of nanowires are critically affected by diameter, length, atomic composition, and nanowire density. Here, we report size controlled growth of silica nanowires by the formation of nanometer sized gold (Au) islands (catalyst particles) during thermal decomposition of Au thin films on

D. K. Venkatachalam; B. Serjeantson; A. Shalav; T. H. Kim; R. G. Elliman

2010-01-01

313

Electrochromic Variable Emittance Devices on Silicon Wafer for Spacecraft Thermal Control  

Microsoft Academic Search

Small light-weight satellites and space vehicles under development for future NASA missions have reduced thermal mass and are strongly affected by changes in orbital conditions, resulting in large temperature variations. Restrictions on payload weight and volume limit the usefulness of many thermal control technologies. One thermal control approach, being considered by NASA in both nano- and micro- spacecraft applications, involves

Nikolai Kislov; Howard Groger; Rengasamy Ponnappan; Edmonia Caldwell; Donya Douglas; Theodore Swanson

2004-01-01

314

Controlled, perfect ordering in ultrathin anodic aluminum oxide templates on silicon  

NASA Astrophysics Data System (ADS)

Ultrathin, perfectly ordered anodic aluminum oxide templates have been produced on supporting substrates by focused ion beam prepatterning. This fast, flexible approach produces pore arrays with both hexagonal and square geometries and allows control over the pore pitch and diameter. The orientation of ordering can be controlled with nanometer precision. Pattern transfer into Si produces pore densities of up to 1011 in.-2.

Robinson, Adam P.; Burnell, Gavin; Hu, Mingzhe; MacManus-Driscoll, Judith L.

2007-10-01

315

Control of Staebler-Wronski defects in hydrogenated amorphous silicon for the development of low cost solar cell technology  

NASA Astrophysics Data System (ADS)

Hydrogenated amorphous silicon (a-Si:H), one of the least expensive solar cell materials, possess an excellent ecological balance sheet. However, the ecological and economic promise of a-Si:H solar cells is limited by the light induced degradation of its electronic properties known as the Staebler-Wronski Effect (SWE). Numerous models have been proposed to explain (and thus control) SWE, with most based on the breaking of weak silicon bonds to create neutral dangling bonds (D0). Evidence, however, has been found for the presence of other defects but such defects have not been characterized in detail. Thus, the predominant application of single defect models has limited the understanding of SWE and the ability to improve a-Si:H materials. This and the lack of correlation between the properties of a-Si:H thin films and corresponding solar cells have had a serious negative effect on the systematic improvement of a-Si:H solar cell performance. This thesis addresses several important issues regarding the properties of protocrystalline a-Si:H materials, the most stable a-Si:H, and their incorporation in cell structures. To improve the understanding of SWE several issues regarding the presence of multiple light induced defects are addressed with detailed studies on thin films. Utilizing AFM, TEM, and real time spectroscopic ellipsometry to track the phase of Si:H, the evolutionary nature (protocrystallinity) and substrate dependence of its growth were further characterized. This allowed highly controlled cell structures to be prepared in which the contributions of the carrier recombination from the p/i interface regions and the bulk could be identified and their effects on cell characteristics separated. For the first time direct correlations between the 1 sun light induced changes in films and solar cells were established in their kinetics at different temperatures. The presence of both 'fast' and 'slow' light induced defects were identified in these degradation kinetics from two clear regimes of degradation for both Fill Factors (FF) in cells and electron mobility-lifetime (mutau) products in thin films. Evidence was found in these studies that not only does the ratio of 'fast' to 'slow' defect states depend on the degradation temperature but also that the 'fast' defects are more negatively charged. A novel approach was developed in analyzing the subgap absorption spectra, alpha(E), extensively used to characterize the light induced defects in a-Si:H. (Abstract shortened by UMI.)

Pearce, Joshua M.

316

Wavefront Control & Sensing System Based on an Opto-Silicon-Integrated Phase Contrast Technique.  

National Technical Information Service (NTIS)

This report describes the design and development of a high-speed, high-resolution wavefront sensing and control system. The system will couple high-resolution analog liquid crystal spatial light modulators with an innovative subtractive imaging sensor. Th...

S. Serati T. Ewing

2002-01-01

317

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.

2009-01-01

318

Energy alignment induced large rectifying behavior in endoheral fullerene dimers  

NASA Astrophysics Data System (ADS)

Using the nonequilibrium Green's function formalism combined with density functional theory for quantum transport calculation, we have investigated the electronic transport properties of three endofullerenes Na@C60C60@F, Na@C60C60, and F@C60C60. The results show that the electronic transport properties of these endofullerenes are strongly dependent upon the species inside the fullerene. A large rectifying behavior is observed in Na@C60C60, while Na@C60C60@F and F@C60C60 can only present very weak rectification. It is revealed that the alignment between the molecular levels of two C60s moieties with the applied bias is the main cause of the large rectification in Na@C60C60.

Zhao, P.; Liu, D. S.; Chen, G.

2013-08-01

319

Individual carbon nanotube Schottky diode rectifiers characterized at microwave frequencies  

NASA Astrophysics Data System (ADS)

Carbon nanotube Schottky diodes (CNT-SDs) are predicted to have very high cut-off frequencies due to small junction capacitances. Additionally, carbon nanotube (CNT) conductors are expected to exhibit signatures of Tomonaga-Luttinger Liquid states in their frequency-dependent conductivity. We have measured the rectification of microwave signals by CNT-SDs as a function of frequency, power, and dc bias voltage. Horizontally aligned CNTs were grown by chemical vapor deposition on high-frequency compatible quartz substrates. Dissimilar metal contacts were created in coplanar waveguide geometries via photolithography. The diodes were subjected to microwave signals from 100MHz to 40GHz. A frequency-independent rectified dc current of approximately 100?A / W was observed throughout this frequency range, consistent with the expected intrinsic cut-off frequency of the devices of order 1THz.

Cobas, Enrique; Anlage, Steven; Fuhrer, Michael

2010-03-01

320

Rectified Brownian movement in molecular and cell biology  

NASA Astrophysics Data System (ADS)

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

Fox, Ronald F.

1998-02-01

321

Direct and Indirect Two-color Coherent Control in Bulk Silicon  

NASA Astrophysics Data System (ADS)

Using an empirical pseudopotential model for electron states and an adiabatic bond charge model for phonon states, we investigate the two-color direct and indirect coherent current injection with an incident optical field composed of a fundamental frequency and its second harmonic, and calculate the response tensors of the electron (hole) charge and spin currents. We show the current control for three different polarization scenarios: For co-circularly polarized beams, the direction of the charge current and the polarization direction of the spin current can be controlled by a relative-phase parameter; for the co-linearly and cross-linearly polarized beams, the current amplitude can be controlled by that parameter. For the indirect gap injection, the spectral dependence of the maximum swarm velocity shows that the direction of charge current reverses under an increase in photon energy.

Cheng, Jinluo; Rioux, Julien; Sipe, John

2012-02-01

322

Thin Films of Silicon on Metallurgical Silicon Substrates. Final Report, 1 September 1976-30 September, 1979.  

National Technical Information Service (NTIS)

The principal approach used in this work is the deposition of a silicon film of controlled thickness and dopant distribution on a purified metallurgical silicon substrate. Efforts have been directed to (1) the purification of metallurgical silicon, (2) th...

T. L. Chu

1979-01-01

323

Silicon quantum dot superstructures for all-silicon tandem solar cells  

Microsoft Academic Search

Motivation Silicon quantum dot absorber layers are used as building blocks for all-silicon tandem solar cells. A control of the Si nanocrystal size allows the adjustment of essential material parameters such as bandgap and oscillator strengths due to size quantization effects. This allows to fabricate silicon based top and middle cells with an engineered and optimized band gap for all-silicon

P. Löper; M. Künle; A. Hartel; J. C. Goldschmidt; M. Peters; S. Janz; M. Hermle; S. W. Glunz; M. Zacharias

324

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

325

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

326

Diameter-Controlled Growth of Multi-Walled Carbon Nanotubes by Hot-Filament Chemical Vapor Deposition with Ferritin as a Catalyst on a Silicon Substrate  

Microsoft Academic Search

Diameter-controlled growth of multi-walled carbon nanotubes (MWNTs) has been achieved by hot-filament chemical vapor deposition with ferritin, a nano-bio-molecule, as a catalyst on a silicon substrate. Ferritin molecules are proteins containing iron oxide cores, which have a uniform diameter dependent on the ferritin size. MWNT growth was performed in a low-pressure chamber using acetylene at 540°C. In contrast to former

Daiyu Kondo; Shintaro Sato; Akio Kawabata; Yuji Awano

2005-01-01

327

Wafer-scale fabrication of silicon nanowire arrays with controllable dimensions  

NASA Astrophysics Data System (ADS)

A novel and facile method was successfully developed to fabricate wafer-scale Si nanowire arrays with well-controlled sizes through the in-situ porous anodic alumina (PAA) template-assisted wet-etching process. The diameter and filling ratio (inter-wire spacing) of the as-prepared Si nanowires are determined by the size and density of pores in the in-situ PAA templates, which can be tailored independently by adjusting the anodization voltages and the immersion time of PAA templates in phosphoric acid. The length of Si nanowires can be more than one hundred micrometers long, which is controlled by adjusting the wet-etching time. Moreover, this method is compatible with complex Si surface topology for creating desirable 3-dimensional hybrid micro/nano-structures. Such Si nanowire arrays exhibit ultralow reflectance and interesting wettability that are of great importance to photovoltaics and thermal management applications.

Wang, Wei; Li, Dan; Tian, Miao; Lee, Yung-Cheng; Yang, Ronggui

2012-09-01

328

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

PubMed

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

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

2012-09-30

329

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

330

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

331

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

332

3D spirals with controlled chirality fabricated using metal-assisted chemical etching of silicon.  

PubMed

The ability to fabricate 3D spiraling structures using metal-assisted chemical etching (MaCE) is one of the unique advantages of MaCE over traditional etching methods. However, control over the chirality of the spiraling structures has not been established. In this work, a systematic parametric study was undertaken for MaCE of star-shaped catalysts, examining the influence of arm shape, arm length, number of arms, center core diameter, and catalyst thickness on the rotation direction. This data was used to identify a set of geometric parameters that reliably induce rotation in a predefined direction such that large arrays of 3D spiraling structures can be fabricated with the same chirality. Electroless deposition into the MaCE template was used to examine the full etch path of the catalyst and an experimental fit was established to control rotation angle by adjusting the catalyst's center core diameter. The ability to fabricate large arrays of 3D spiraling structures with predefined chirality could have important applications in photonics and optoelectronics. PMID:23039816

Hildreth, Owen J; Fedorov, Andrei G; Wong, Ching Ping

2012-10-10

333

Comparison of Silicon UMOSFETs Versus GaAs Vertical FETs For Low Voltage, Synchronous Rectification at 2.5 MHz.  

National Technical Information Service (NTIS)

A comparison between the rectification efficiency of silicon UMOSFETs versus GaAs vertical FETs in a 1.5 volt, 2.5 megahertz power supply application is presented. A new figure of merit describing conduction and switching losses of synchronous rectifiers ...

R. Kollman G. Sills J. Yuan T. Syau P. Venkatraman

1992-01-01

334

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

SciTech Connect

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

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

2008-04-15

335

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

336

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

NASA Astrophysics Data System (ADS)

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

Shul, Randy

2003-10-01

337

Threshold-voltage tuning characteristics of all-organic electrochemical vertical rectifiers on flexible substrates  

Microsoft Academic Search

A printed all-organic electrochemical vertical tunable rectifier is demonstrated using a conducting polymer as the active material on a flexible plastic substrate. Solution processable poly(3,4-ethylenedioxythiophene) combined with poly(styrene sulfonic acid) (PEDOT:PSS) was coated on polyester film; the rectifier channel was patterned on the PEDOT:PSS film through directly writing technique without the need for masks, patterns, or dies. A vertically layered

Miaoxiang Chen

2006-01-01

338

Voltage sag ride-through for adjustable-speed drives with active rectifiers  

Microsoft Academic Search

Adjustable-speed drives (ASDs) trip due to voltage sags, interfering with production and resulting in financial losses. In this paper, a methodology for incorporating voltage sag ride-through in the design of ASDs with active rectifiers is presented. The magnitude of the voltage sag for which ride-through can be provided is determined by the current rating of the active rectifier and load

Annabelle van Zyl; R. Spee; A. Faveluke; S. Bhowmik

1998-01-01

339

Characterization of the chicken inward rectifier K+ channel IRK1\\/Kir2.1 gene  

Microsoft Academic Search

BACKGROUND: Inward rectifier potassium channels (IRK) contribute to the normal function of skeletal and cardiac muscle cells. The chick inward rectifier K+ channel cIRK1\\/Kir2.1 is expressed in skeletal muscle, heart, brain, but not in liver; a distribution similar but not identical to that of mouse Kir2.1. We set out to explore regulatory domains of the cIRK1 promoter that enhance or

Hideki Mutai; Lawrence C Kenyon; Emily Locke; Nami Kikuchi; John Carl Oberholtzer

2004-01-01

340

Voltage, efficiency calculation and measurement of low power rectenna rectifying circuit  

Microsoft Academic Search

In this paper, we present zero-bias Schottky diode and rectifier circuit models for a low power (⩽ 0 dBm) rectenna rectifying circuit. These models rely primarily on data obtained from the diode characteristic curve measurement. The zero-bias Schottky diode model provides diode parameters at the desired output DC current level to be matched with the antenna so that optimum power

Jurianto Joe; Michael Y. W. Chia

1998-01-01

341

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

Microsoft Academic Search

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

Yogesh K. Ramadass; Anantha P. Chandrakasan

2010-01-01

342

Analysis and design of an efficient RF\\/DC rectifier for UHF power harvester  

Microsoft Academic Search

An efficient RF-to-DC rectifier for UHF power harvester at 915MHz ISM band is presented. Systematic design and analysis are involved in the study. An optimal 7-stage RF-to-DC rectifier was designed and fabricated in TSMC 0.18um MM\\/RF CMOS process. Experimental measurement results showed that the proposed circuit had a power sensitivity of -9.5dBm while maintaining a DC output voltage of 1.2V

Sau-Mou Wu; Chun-Yuan Lin; Lan-Ching Pai

2010-01-01

343

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

344

The fabrication of highly ordered block copolymer micellar arrays: control of the separation distances of silicon oxide dots  

NASA Astrophysics Data System (ADS)

We demonstrate the fabrication of highly ordered silicon oxide dotted arrays prepared from polydimethylsiloxane (PDMS) filled nanoporous block copolymer (BCP) films and the preparation of nanoporous, flexible Teflon or polyimide films. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films were annealed in toluene vapor to enhance the lateral order of micellar arrays and were subsequently immersed in alcohol to produce nano-sized pores, which can be used as templates for filling a thin layer of PDMS. When a thin layer of PDMS was spin-coated onto nanoporous BCP films and thermally annealed at a certain temperature, the PDMS was drawn into the pores by capillary action. PDMS filled BCP templates were exposed to oxygen plasma environments in order to fabricate silicon oxide dotted arrays. By addition of PS homopolymer to PS-b-P2VP copolymer, the separation distances of micellar arrays were tuned. As-prepared silicon oxide dotted arrays were used as a hard master for fabricating nanoporous Teflon or polyimide films by spin-coating polymer precursor solutions onto silicon patterns and peeling off. This simple process enables us to fabricate highly ordered nanoporous BCP templates, silicon oxide dots, and flexible nanoporous polymer patterns with feature size of sub-20 nm over 5 cm × 5 cm.

Yoo, Hana; Park, Soojin

2010-06-01

345

Synthesis and modification of silicon nanosheets and other silicon nanomaterials.  

PubMed

Silicon nanomaterials and nanostructures exhibit different properties from those of bulk silicon materials based on quantum confinement effects. They are expected to lead to the development of new applications of silicon, in addition to wide use in semiconductor devices. Aside from industrial interest, intriguing issues of academic interest still remain with respect to the origins of their characteristic properties. Zero- and one-dimensional crystalline silicon nanomaterials have been synthesized, to date, by using many methods and there has been rapid progress in size control and modification procedures. However, there have been only a few examples of silicon nanomaterials with atomic-order thickness akin to carbon nanomaterials, such as two-dimensional silicon nanosheets. Moreover, mass production of silicon nanomaterials with relatively low cost is not easily achievable, due to the typically severe conditions required for fabrication, such as high temperature and ultralow pressure. Recently, we have developed a soft synthetic method for silicon nanosheets with chemical surface modification in a solution process. This review provides methods for the synthesis and modification of silicon nanosheets and other silicon nanomaterials with examples of their potential applications. PMID:21780200

Okamoto, Hirotaka; Sugiyama, Yusuke; Nakano, Hideyuki

2011-07-20

346

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.

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

2011-01-01

347

New analysis and design of a RF rectifier for RFID and implantable devices.  

PubMed

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 suitable to 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

2011-06-24

348

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

349

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

Microsoft Academic Search

A simple method for fabricating silicon electrodes with various shapes and gap widths was designed using the special properties of anisotropic tetramethylammonium hydroxide (TMAH) wet etching and local anodic oxidation (LAO). A statistical system was used for the optimization of the parameters of the LAO process to facilitate a better understanding and precise analysis of the process. Analyses of the

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

2012-01-01

350

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

Microsoft Academic Search

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

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

2010-01-01

351

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

Microsoft Academic Search

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

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

2010-01-01

352

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

PubMed Central

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

Remillard, C V; Leblanc, N

1996-01-01

353

Strategies to Improve Silicone Elastomer Biocompatibility  

Microsoft Academic Search

Silicone polymers, particularly elastomers, are widely used biomaterials in applications as diverse as wound dressings, hydrocephalic shunts, breast implants and intraocular lenses. 1 While many of the properties of silicones are particularly useful for these applications, including transparency, facile control of shape, high oxygen permeability and good biocompatibility, there can be issues with these polymers in biomaterials applications. Silicone polymers,

Michael A. Brook; Heather D. Sheardown; Alison Holloway; d Shao; Ken Ng; Johan Alauzun

354

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.

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

2012-01-01

355

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

356

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

Microsoft Academic Search

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

W. F. Praeg

1965-01-01

357

Porous Silicon  

Microsoft Academic Search

Electrochemical etching in solutions based on hydrofluoric acid has been widely used to form light-emitting porous silicon. However, the effects of a number of the experimental parameters on the quality of the porous silicon produced have yet to be fully investigated. In the present paper the influence of temperature and viscosity of the etching solution is evaluated in terms of

D. J. Blackwood; Y. Zhang

2001-01-01

358

Silicones: unique chemicals for petroleum processing  

SciTech Connect

Silicones are specialty chemicals that are often critical in certain production operations. Their primary use in petroleum applications is as foam control agents. The physical and chemical properties of silicones are described, and foam and antifoam theory is discussed. State-of-the-art silicone use in selected key petroleum applications is outlined. The unique properties of silicones that should be considered by petroleum engineers in solving problems in other types of applications are emphasized.

Pape, P.G.

1983-06-01

359

Interactions of Cations with the Cytoplasmic Pores of Inward Rectifier K+ Channels in the Closed State  

PubMed Central

Ion channels gate at membrane-embedded domains by changing their conformation along the ion conduction pathway. Inward rectifier K+ (Kir) channels possess a unique extramembrane cytoplasmic domain that extends this pathway. However, the relevance and contribution of this domain to ion permeation remain unclear. By qualitative x-ray crystallographic analysis, we found that the pore in the cytoplasmic domain of Kir3.2 binds cations in a valency-dependent manner and does not allow the displacement of Mg2+ by monovalent cations or spermine. Electrophysiological analyses revealed that the cytoplasmic pore of Kir3.2 selectively binds positively charged molecules and has a higher affinity for Mg2+ when it has a low probability of being open. The selective blocking of chemical modification of the side chain of pore-facing residues by Mg2+ indicates that the mode of binding of Mg2+ is likely to be similar to that observed in the crystal structure. These results indicate that the Kir3.2 crystal structure has a closed conformation with a negative electrostatic field potential at the cytoplasmic pore, the potential of which may be controlled by conformational changes in the cytoplasmic domain to regulate ion diffusion along the pore.

Inanobe, Atsushi; Nakagawa, Atsushi; Kurachi, Yoshihisa

2011-01-01

360

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

NASA Astrophysics Data System (ADS)

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

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

1991-10-01

361

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

362

A new approach for three-phase three-level unity PF rectifier considering alternative performance indices  

Microsoft Academic Search

The three-phase three-level unity PF rectifier can improve the power factor of three-phase rectifier. However, both the power factor (PF) and total harmonic distortion (THD) are degraded in low-output power region, because its “critical input inductor” is calculated for the nominal load condition. A novel reference compensation current strategy for three-phase three-level unity PF rectifier considering alternative performance indices was

Shaoru Zhang; Fang Lin Luo

2010-01-01

363

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

364

Control of a stand alone variable speed wind turbine with a permanent magnet synchronous generator  

Microsoft Academic Search

A novel control strategy for the operation of a permanent magnet synchronous generator (PMSG) based stand alone variable speed wind turbine is presented in this paper. The direct drive PMSG is connected to the load through a switch mode rectifier and a vector controlled pulse width modulated (PWM) IGBT-inverter. The generator side switch mode rectifier is controlled to achieve maximum

M. E. Haque; K. M. Muttaqi; M. Negnevitsky

2008-01-01

365

A new approach to combatting iodine deficiency in developing countries: the controlled release of iodine in water by a silicone elastomer.  

PubMed Central

OBJECTIVES. Four hundred million people or more may be exposed to iodine deficiency worldwide, in developing countries in particular. Because of the practical problems with existing methods for the large-scale prevention of iodine deficiency, the authors developed a new approach to collective prophylaxis. METHODS. This approach relies on the controlled diffusion of iodine into water from a silicone elastomer. Silicone matrices installed in a bore well released iodine at a rate sufficient to permit the daily per capita intake of at least 100 micrograms of iodine, the amount recommended by the World Health Organization. The matrices were tested over 1 year in a village in Mali, West Africa, an area in which goiter was highly endemic. The effects on the well water and population were compared with those of a placebo system in a control village. RESULTS. An increase in urinary iodine levels was observed in the treated population, and after 12 months the incidence of goiter had fallen from 53.2% to 29.2%. CONCLUSIONS. This new concept, adaptable to all sources of water supply, may contribute to the eradication of iodine deficiency.

Fisch, A; Pichard, E; Prazuck, T; Sebbag, R; Torres, G; Gernez, G; Gentilini, M

1993-01-01

366

Investigation of device geometry- and temperature-dependent characteristics of AlGaN/GaN lateral field-effect rectifier  

NASA Astrophysics Data System (ADS)

The temperature-dependent characteristics of AlGaN/GaN lateral field-effect rectifiers (L-FER) are studied in detail by investigating the dependence of forward and reverse characteristics on the device geometry (Schottky-gate-controlled channel) and temperature. The forward current increased with the decrease of channel length, while the specific on-resistance showed a positive temperature coefficient. Moreover, different temperature-dependent reverse characteristics were observed for the L-FERs with different device geometries. A combination of impact ionization in the Schottky-gate-controlled channel and the Schottky reverse leakage current is applied to understand the reverse breakdown of L-FER.

Chen, Wanjun; Zhang, Jing; Wang, Zhigang; Wei, Jin; Zhang, Bo; Chen, Kevin J.

2013-01-01

367

Orbital-selective single molecule rectifier on graphene-covered Ru(0001) surface  

NASA Astrophysics Data System (ADS)

We demonstrate that the tunable molecule-substrate interaction offers possibility to realize a single cobalt phthalocyanine (CoPc) molecule rectifier. CoPc molecule shows a prominent rectifying effect at about -0.30 eV when a monolayer graphene (MG) is intercalated between CoPc and Ru(0001) substrate. First-principles calculations show that CoPc molecule couples with MG/Ru(0001) substrate mainly through the dz2 orbital of Co atom. The tunneling between CoPc molecule and MG/Ru(0001) substrate is mainly intermediated by the Co-dz2 orbital locating at -0.35 eV. The resonant tunneling through this single orbital gives rise to the abrupt current enhancement and hence the rectifying effect.

Lei, Shulai; Feng, Wei; Li, Bin; Li, Qunxiang; Zhao, Aidi; Wang, Bing; Yang, Jinlong; Hou, J. G.

2013-04-01

368

Silicon nitride/silicon carbide composite powders  

DOEpatents

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

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

1996-06-11

369

Diamond coating on silicon nitride by intermittent discharge DC plasma chemical vapor deposition  

Microsoft Academic Search

A new diamond coating method on a silicon nitride throw away chip (SNTAC) by intermittent discharge DC plasma chemical vapor deposition (CVD), where the wave-form of the discharge is half-wave-rectified (HWR), has been developed. The coating was performed by exposing SNTAC in the plasma The discharge to form the plasma is performed by applying the voltage of HWR between the

Tomoyoshi Araki; Mikio Noda; Takashi Katsuyama

1997-01-01

370

Observation and explanation of multistable nonvolatile memory in silicon FIT diodes  

Microsoft Academic Search

Point-contact, Schottky, and diffused-silicon diodes doped with copper and iron impurities have been fabricated. These diodes show multistable behavior at room temperature, exhibiting a wide range of easily discriminated nonvolatile I-V rectifying characteristics (class I behavior). The class I behavior is explained in terms of field-induced trapping (FIT) with stationary space-charge domain formation in or near the depletion region. If

James W. Holm-Kennedy; David L. Heald; George Williams; Yu-Wen Chang

1973-01-01

371

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

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

372

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

PubMed Central

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

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

2011-01-01

373

Crossbar memory array of organic bistable rectifying diodes for nonvolatile data storage  

NASA Astrophysics Data System (ADS)

Cross-talk in memories using resistive switches in a cross-bar geometry can be prevented by integration of a rectifying diode. We present a functional cross bar memory array using a phase separated blend of a ferroelectric and a semiconducting polymer as storage medium. Each intersection acts simultaneously as a bistable rectifying diode. A logic table of a 4-bit memory and integration into a 3×3 cross bar array are demonstrated. The most difficult state, a high resistance bit completely surrounded by low resistance bits could be unambiguously identified.

Asadi, Kamal; Li, Mengyuan; Stingelin, Natalie; Blom, Paul W. M.; de Leeuw, Dago M.

2010-11-01

374

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

375

Notched Circular Microstrip Patch Antenna integrated with a single diode rectifier for energy-harvesting prosthetic leg  

Microsoft Academic Search

In this paper, we describe an RF energy- harvesting circuit printed on a single FR4 substrate to ensure compact and low profile design at 2.1 GHz. The circuit integrates a notched Circular Microstrip Patch Antenna (CMPA) with a fully matched single diode rectifier to form an efficient rectifying antenna. By cutting two electrically small triangular notches, at 45 0 and

C. Mikeka; H. Arai

2011-01-01

376

Elevated serum silicon levels in women with silicone gel breast implants  

Microsoft Academic Search

The metatolic fate of silicone gel leaked from an intact or ruptured prosthesis is unknown. In this study, serum was blindly\\u000a assayed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) for elemental silicon in 72 women with silicone\\u000a gel breast implants and 55 control women (mean age 48 yr, both groups). Blood was drawn and processed using silicon-free materials.\\u000a The

Suzanne S. Teuber; Robert L. Saunders; Georges M. Halpern; Robert F. Brucker; Victor Conte; Brian D. Goldman; Edward E. Winger; W. Graham Wood; M. Eric Gershwin

1995-01-01

377

Ten-year review of a prospective randomized controlled trial of textured versus smooth subglandular silicone gel breast implants.  

PubMed

Although textured silicone breast implants have been shown to reduce the incidence of capsular contracture, there is little evidence if this effect is maintained in the long term. It has been 10 years since the double-blind randomized trial in which 53 patients received either Mentor smooth (26) or textured silicone gel implants (27). Of the 14 patients who were not known to have developed a contracture in the smooth group, 11 were reviewed. Three had bilateral contractures. In the textured group, 18 of the 24 patients not known to have contractures were reviewed. None had developed contractures. At 10 years, the incidence of capsular contracture was 65 percent of patients with smooth implants (an increase of 6 percent on the 3-year results) and 11 percent for the textured implant patients (no change on the 3-year results). A database containing the details of 1100 patients reinforces these results by examining the differences in contracture rates of textured, smooth, and polyurethane-coated implants. The effect of submuscular placement on reducing contracture rates regardless of texturing is discussed, as is the apparent increase in capsular contracture in patients who smoke. PMID:11007389

Collis, N; Coleman, D; Foo, I T; Sharpe, D T

2000-09-01

378

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

PubMed Central

Following initial infection, herpesviruses retreat into a permanent latent state with periodic reactivation resulting in an enhanced likelihood of transmission and clinical disease. The nucleoside analogue acyclovir reduces clinical symptoms of the three human alpha herpesviruses, HSV-1, HSV-2, and VZV. Long-term administration of acyclovir (ACV) can reduce the frequency and severity of reactivation, but its low bioavailability and short half-life require a daily drug regimen. Our lab is working to develop a subcutaneous delivery system to provide long-lasting, sustained release of ACV. Previously, we demonstrated that an implantable silicone (MED-4050) device, impregnated with ACV protected against HSV-1 both in vitro and in vivo. Here, we extend our in vitro observations to include protection against both HSV-2 and VZV. We also demonstrate protection against HSV-2 in vitro using MED-4750, a silicone polymer designed for long-term use in humans. When release of ACV from MED-4750 is quantitated on a daily basis, an initial burst of 5 days is observed, followed by a long period of slow release with near-zero-order kinetics, with an average daily release of 1.3923 ± 0.5908??g ACV over days 20–60. Development of a slow-release implant has the potential to significantly impact the treatment of human alpha herpesvirus infections.

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

2013-01-01

379

Intelligent energy saving power system control of telecom DC power plant  

Microsoft Academic Search

This paper presents the design of intelligent energy saving power system controller (IESPSC) in a DC power plant of Korean Telecommunications. From past experience, rectifiers for telecom DC power plants have been very inefficient at light loads. The proposed control scheme offers a “novel load sharing” approach based on the knowledge of each unit's efficiency in parallel rectifiers. Neural networks

J. Y. Choi; I. Choy; T. Y. Kim; S. W. Gu

1996-01-01

380

Immunopathology of intraocular silicone oil: enucleated eyes  

PubMed Central

Aims To characterise the distribution of silicone oil in ocular tissues in globes enucleated after complicated retinal detachment, and to document the distribution and nature of any associated inflammatory response. Method 9 enucleated globes that had previously undergone retinal detachment surgery with silicone oil and 7 control globes that had undergone enucleation after retinal detachment surgery (n?=?2) or ocular trauma (n?=?5) were studied. Sections were histologically examined using light microscopy to document the distribution of silicone oil in ocular tissues. Immunohistochemical analysis was carried out using the ABC technique and a panel of monoclonal and polyclonal antibodies. Electron microscopy was undertaken to observe the penetration of silicone oil in the trabecular meshwork of the anterior chamber drainage angle. Results Silicone oil was distributed throughout the globes—notably in the iris, ciliary body, retina, trabecular meshwork and epiretinal membranes. Focal areas of intraretinal silicone were associated with disorganised retinal architecture, retinectomy sites or subretinal oil. The distribution of macrophages was closely related to the distribution of silicone oil. T and B lymphocytes were not associated with silicone oil unless additional pathology was also present—for example, cyclitic membrane or uveitis. One of the nine eyes had silicone oil present in the optic nerve. In the control globes, the inflammatory response was mediated primarily by macrophages and T lymphocytes, and was less marked than that observed in the silicone oil globes. Conclusion This study shows that silicone oil may be sequestered in varied ocular tissues and is associated with localised inflammation mediated by macrophages.

Wickham, Louisa; Asaria, Riaz H; Alexander, Robert; Luthert, Phil; Charteris, David G

2007-01-01

381

An open rectifier potassium channel with two pore domains in tandem cloned from rat cerebellum.  

PubMed

Tandem pore domain K+ channels represent a new family of ion channels involved in the control of background membrane conductances. We report the structural and functional properties of a TWIK-related acid-sensitive K+ channel (rTASK), a new member of this family cloned from rat cerebellum. The salient features of the primary amino acid sequence include four putative transmembrane domains and, unlike other cloned tandem pore domain channels, a PDZ (postsynaptic density protein, disk-large, zo-1) binding sequence at the C terminal. rTASK has distant overall homology to a putative Caenorhabditis elegans K+ channel and to the mammalian clones TREK-1 and TWIK-1. rTASK expression is most abundant in rat heart, lung, and brain. When exogenously expressed in Xenopus oocytes, rTASK currents activate instantaneously, are noninactivating, and are not gated by voltage. Because rTASK currents satisfy the Goldman-Hodgkin-Katz current equation for an open channel, rTASK can be classified an open rectifier. Activation of protein kinase A produces inhibition of rTASK, whereas activation of protein kinase C has no effect. rTASK currents were inhibited by extracellular acidity. rTASK currents also were inhibited by Zn2+ (IC50 = 175 microM), the local anesthetic bupivacaine (IC50 = 68 microM), and the anti-convulsant phenytoin ( approximately 50% inhibition at 200 microM). By demonstrating open rectification and open probability independent of voltage, we have established that rTASK is a baseline potassium channel. PMID:9437008

Leonoudakis, D; Gray, A T; Winegar, B D; Kindler, C H; Harada, M; Taylor, D M; Chavez, R A; Forsayeth, J R; Yost, C S

1998-02-01

382

MicroRNA-26 governs profibrillatory inward-rectifier potassium current changes in atrial fibrillation  

PubMed Central

Atrial fibrillation (AF) is a highly prevalent arrhythmia with pronounced morbidity and mortality. Inward-rectifier K+ current (IK1) is believed to be an important regulator of reentrant-spiral dynamics and a major component of AF-related electrical remodeling. MicroRNA-26 (miR-26) is predicted to target the gene encoding KIR2.1, KCNJ2. We found that miR-26 was downregulated in atrial samples from AF animals and patients and this downregulation was accompanied by upregulation of IK1/KIR2.1 protein. miR-26 overexpression suppressed expression of KCNJ2/KIR2.1. In contrast, miR-26 knockdown, inhibition, or binding-site mutation enhanced KCNJ2/KIR2.1 expression, establishing KCNJ2 as a miR-26 target. Knockdown of endogenous miR-26 promoted AF in mice, whereas adenovirus-mediated expression of miR-26 reduced AF vulnerability. Kcnj2-specific miR-masks eliminated miR-26–mediated reductions in Kcnj2, abolishing miR-26’s protective effects, while coinjection of a Kcnj2-specific miR-mimic prevented miR-26 knockdown-associated AF in mice. Nuclear factor of activated T cells (NFAT), a known actor in AF-associated remodeling, was found to negatively regulate miR-26 transcription. Our results demonstrate that miR-26 controls the expression of KCNJ2 and suggest that this downregulation may promote AF.

Luo, Xiaobin; Pan, Zhenwei; Shan, Hongli; Xiao, Jiening; Sun, Xuelin; Wang, Ning; Lin, Huixian; Xiao, Ling; Maguy, Ange; Qi, Xiao-Yan; Li, Yue; Gao, Xu; Dong, Deli; Zhang, Yong; Bai, Yunlong; Ai, Jing; Sun, Lihua; Lu, Hang; Luo, Xiao-Yan; Wang, Zhiguo; Lu, Yanjie; Yang, Baofeng; Nattel, Stanley

2013-01-01

383

Estrogen directly acts on osteoclasts via inhibition of inward rectifier K+ channels.  

PubMed

Using the whole-cell patch-clamp technique in freshly isolated rat osteoclasts we examined the effects of estrogen on ionic channels. The predominant current was an inward rectifier K+ current (IKir). In the absence of non-osteoclastic cells, extracellularly applied 17beta-estradiol (>0.1 microM) inhibited IKir, indicating that estrogen acts directly on osteoclasts. Application of 17beta-estradiol (10 microM) for 10 min reduced IKir at the membrane potential of -120 mV to 70 +/- 15% of control. Removal of 17beta-estradiol partially restored the inhibition. The inhibition of IKir was dependent on concentration and application time. Intracellularly applied 17beta-estradiol had no effect on IKir. 17alpha-estradiol also inhibited the IKir, whereas progesterone and testosterone had no effect. The inhibitory action of 17beta-estradiol was not affected by guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), adenosine 3',5'-cyclic monophosphothioate Rp diastereomer (Rp-cAMPS), okadaic acid, staurosporine and phorbol ester, and was independent of intracellular Ca2+ concentration ([Ca2+]i). With no influence from soluble factors secreted from non-osteoclastic cells, preincubation of the osteoclasts for more than 60 min with much lower concentrations of 17beta-estradiol (1 and 10 nM) caused a reduction of IKir. In current-clamp configuration, application of 17beta-estradiol (10 microM) depolarized the membrane associated with a decrease in a membrane conductance, indicating that 17beta-estradiol inhibits IKir and depolarizes the membrane of osteoclasts. These results suggest that the 17beta-estradiol-induced inhibition of IKir might be mediated via non-genomic mechanisms. This direct action of 17beta-estradiol on osteoclasts may contribute to the regulation of [Ca2+]i and partially account for the protective effects of estrogen against bone loss. PMID:10882036

Okabe, K; Okamoto, F; Kajiya, H; Takada, K; Soeda, H

2000-06-01

384

Homoazeotropic distillation of maximum azeotropes in a batch rectifier with continuous entrainer feeding I. Feasibility studies  

Microsoft Academic Search

Our former method for the assessment of the feasibility of extractive distillation in a batch rectifier was extended for the investigation of the separation of maximum azeotropes. The method is based on the calculation of the still path and possible composition profiles of the column sections. The sequence of the separation steps was determined, then limiting values and the influence

P. Lang; G. Modla; B. Benadda; Z. Lelkes

2000-01-01

385

Three-Phase Boost Active Power Factor Correction for Diode Rectifiers.  

National Technical Information Service (NTIS)

This report documents an investigation and implementation of a 3 kW active power factor correction (pfc) design used to enable a diode rectifier to draw sinusoidal line currents with nearly unity power factor from a three-phase utility grid. The design ut...

J. G. Nairus

1996-01-01

386

Predictive diagnostics for the main field winding and rotating rectifier assembly in the brushless synchronous generator  

Microsoft Academic Search

On-line predictive diagnostics can be an effective tool for minimizing overall maintenance costs and reducing system down time. In this paper, a method for detecting the onset of field winding and rotating rectifier failure modes in the brushless synchronous generator is presented A theoretical analysis of the brushless generator is first carried out to establish the effects of the two

Todd D. Batzel; David C. Swanson; John F. Defenbaugh

2003-01-01

387

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

Microsoft Academic Search

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

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

2009-01-01

388

A hybrid wind-solar energy system: A new rectifier stage topology  

Microsoft Academic Search

Environmentally friendly solutions are becoming more prominent than ever as a result of concern regarding the state of our deteriorating planet. This paper presents a new system configuration of the front-end rectifier stage for a hybrid wind\\/photovoltaic energy system. This configuration allows the two sources to supply the load separately or simultaneously depending on the availability of the energy sources.

Joanne Hui; A. Bakhshai; P. K. Jain

2010-01-01

389

Bubble growth within the skin by rectified diffusion might play a significant role in sonophoresis  

Microsoft Academic Search

Low frequency ultrasound has successfully been used for enhancing transdermal transport of a variety of different molecules. This phenomenon is referred to as sonophoresis. Several attempts have been made to investigate the enhancing mechanism in order to modulate the overall process.In this study we assess whether rectified diffusion is a process that occurs within the skin, which could eventually lead

Ilana Lavon; Nili Grossman; Joseph Kost; Eitan Kimmel; Giora Enden

2007-01-01

390

Asymptotics for discrete weighted minimal Riesz energy problems on rectifiable sets  

Microsoft Academic Search

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

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

2008-01-01

391

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

392

Influences of the N- and C-Termini of the Distal Nephron Inward Rectifier, ROMK  

Microsoft Academic Search

The inward rectifying potassium channels of the ROMK family are present in the distal nephron of the kidney. These channels have two membrane spanning portions, between which lies a hydrophobic domain thought to confer the majority of the conductive properties of the channel. The N- and C-termini are both intracellular. In this paper we have examined the contribution of the

Sunil Bhandari; Malcolm Hunter

2001-01-01

393

A simple and efficient synchronous rectifier for forward DC-DC converters  

Microsoft Academic Search

A simple and efficient MOSFET synchronous rectification circuit suitable for forward DC-DC power converters is proposed. The main feature of this circuit is the addition of a capacitor in parallel with the drain source of the MOSFET used as a rectifying device. This capacitor extends the conduction period of the MOSFET used as a freewheeling device. As a result, a

N. Murakami; H. Namiki; K. Sakakibara; T. Yachi

1993-01-01

394

Substituent variation drives metal/monolayer/semiconductor junctions from strongly rectifying to ohmic behavior.  

PubMed

An eight-orders of magnitude enhancement in current across Hg/X-styrene-Si junctions is caused by merely altering a substituent, X. Interface states are passivated and, depending on X, the Si Schottky junction encompasses the full range from Ohmic to strongly rectifying. This powerful electrostatic molecular effect has immediate implications for interface band alignment and sensing. PMID:23161521

Haj-Yahia, Abd-Elrazek; Yaffe, Omer; Bendikov, Tatyana; Cohen, Hagai; Feldman, Yishay; Vilan, Ayelet; Cahen, David

2012-11-19

395

Rectifying electrical synapses can affect the influence of synaptic modulation on output pattern robustness.  

PubMed

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; Marder, Eve

2013-08-01

396

Rectifier and DC bus system design for the copper electrowinning industry  

Microsoft Academic Search

Some of the design features of the rectifier and DC bus system that supply the direct current for the electrowinning process as discussed. As background information, a brief description of the solvent extraction (SX) and electrowinning (EW) process is given. The four basic steps to the SC\\/EW process include leaching, extraction, stripping, and electrowinning. Some of the design features of

R. R. Brown

1990-01-01

397

An improved high-power factor and low-cost three-phase rectifier  

Microsoft Academic Search

A new method to improve the power factor of three-phase rectifiers is introduced in this paper. The main features of the proposed circuit are low cost, small size, high efficiency, and simplicity. The power factor improvement is achieved with three bi-directional active switches rated at a small fraction of the total processed power, and gated at the line frequency. The

Ewaldo L. M. Mehl; Ivo Barbi

1997-01-01

398

Rectifier and DC bus systems design for the copper electrowinning industry  

Microsoft Academic Search

It is noted that the use of DC rectifiers and DC bus systems for the copper electrowinning industry has become more widespread during the last 10 years due to the refinement of the solvent extraction process, which has made electrowinning one of the most cost-effective methods of producing copper. The author discusses some of the design features of the large

R. R. Brown

1989-01-01

399

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

PubMed

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

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

2012-08-01

400

Optimization of output voltage and stage number of UHF RFID power rectifier  

Microsoft Academic Search

In UHF RFID tag IC, multiple charge-pump stages are needed to form a rectifier for achieving a sufficiently high output voltage to supply the other circuit blocks. To save chip area and achieve a high output voltage simultaneously, the number of charge-pump stages should be optimized in accordance with the amplitude of the RF input signal. In this paper, an

Jingbin Jia; Ka Nang Leung

2010-01-01

401

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

402

Single Channel Studies of Inward Rectifier Potassium Channel Regulation by Muscarinic Acetylcholine Receptors  

Microsoft Academic Search

Negative regulation of the heartbeat rate involves the activation of an inwardly rectifying potassium current (I KACh ) by G protein-coupled receptors such as the m2 muscarinic acetylcholine receptor. Recent studies have shown that this process involves the direct binding of G bg subunits to the NH 2 - and COOH-terminal cytoplas- mic domains of the proteins termed GIRK1 and

Joel Bard; Maya T. Kunkel; Ernest G. Peralta

2000-01-01

403

Inhibition of G Protein-Activated Inwardly Rectifying K+ Channels by Different Classes of Antidepressants  

Microsoft Academic Search

Various antidepressants are commonly used for the treatment of depression and several other neuropsychiatric disorders. In addition to their primary effects on serotonergic or noradrenergic neurotransmitter systems, antidepressants have been shown to interact with several receptors and ion channels. However, the molecular mechanisms that underlie the effects of antidepressants have not yet been sufficiently clarified. G protein-activated inwardly rectifying K+

Toru Kobayashi; Kazuo Washiyama; Kazutaka Ikeda

2011-01-01

404

Inhibition by cocaine of G protein-activated inwardly rectifying K + channels expressed in Xenopus oocytes  

Microsoft Academic Search

Cocaine, a commonly abused psychostimulant, interacts with not only transporters for dopamine, serotonin and norepinephrine but also several receptors and channels. However, the molecular mechanisms underlying the various effects of cocaine remain to be clarified. Using the Xenopus oocyte expression assay, we investigated the effects of cocaine on G protein-activated inwardly rectifying K+ (GIRK) channels, which regulate neuronal excitability and

Toru Kobayashi; Daisuke Nishizawa; Tatsunori Iwamura; Kazutaka Ikeda

2007-01-01

405

G-protein-coupled inwardly rectifying potassium channels are targets of alcohol action  

Microsoft Academic Search

G-protein-coupled inwardly rectifying potassium channels (GIRKs) are important for regulation of synaptic transmission and neuronal firing rates. Because of their key role in brain function, we asked if these potassium channels are targets of alcohol action. Ethanol enhanced function of cerebellar granule cell GIRKs coupled to GABAB receptors. Enhancement of GIRK function by ethanol was studied in detail using Xenopus

Walter R. Wilson; R. Dayne Mayfield; Susan J. Brozowski; Richard A. Morrisett; R. Adron Harris; Joanne M. Lewohl

1999-01-01

406

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

Microsoft Academic Search

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

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

2009-01-01

407

Quick-charging a sealed lead-acid battery with unregulated transformer-rectifiers  

NASA Astrophysics Data System (ADS)

An overview is given of sealed lead-acid battery advantages. Unregulated transformer-rectifier unit flat charging advantages are discussed, and a proposed modified charging method is presented. A test plan to verify the system along with expected results is presented.

Kuest, Jeffrey S.; Borges de Oliveira, A.

408

Uncooled THz/sub-THz Rectifying Detectors: FET vs. SBD  

NASA Astrophysics Data System (ADS)

The parameters (responsivity R and noise equivalent power (NEP)) of long channel unbiased (zero drain-source bias (V DS = 0)) silicon field effect transistors (FET) as THz/sub-THz detectors with account of some parasitics were considered. These parameters and their radiation frequency ? dependences are compared with those of contemporary Schottky barrier diode (SBD) THz/sub-THz detectors. To describe and compare the known experimental data for both of detectors similar models, taking into account the parasitics (some FET or SBD resistances and capacities), were used. It is shown that taking into account the parasitics and detector-antenna impedance matching one can describe Si FET detector parameters and estimate the performance limits of such detectors. The R and NEP radiation frequency ? dependences are similar for FET and SBD detectors and are proportional to ? -2 or to ? -4. The model used for SBD detectors describes well the known experimental data for optical NEP opt but for Si FET ones the sufficient scatter in experimental data is observed. The reason of it seems is mainly due to non-optimized technologies for FETs as detectors for THz/sub-THz radiation.

Sakhno, M.; Sizov, F.; Golenkov, A.

2013-09-01

409

Comparison of confinement characters between porous silicon and silicon nanowires  

Microsoft Academic Search

Confinement character and its effects on photoluminescence (PL) properties are theoretically investigated and compared between porous silicon (p-Si) and silicon nanowires (Si-NWs). The method is based on the application of the tight-binding technique using the minimal sp3-basis set, including the second-nearest-neighbor interactions. The results show that the quantum confinement (QC) is not entirely controlled by the porosity, rather it is

Nacir Tit; Zain H. Yamani; Giovanni Pizzi; Michele Virgilio

2011-01-01

410

Front-end circuit for position sensitive silicon and vacuum tube photomultipliers with gain control and depth of interaction measurement  

NASA Astrophysics Data System (ADS)

Silicon Photomultipliers, though still under development for mass production, may be an alternative to traditional Vacuum Photomultipliers Tubes (VPMT). As a consequence, electronic front-ends initially designed for VPMT will need to be modified. In this simulation, an improved architecture is presented which is able to obtain impact position and depth of interaction of a gamma ray within a continuous scintillation crystal, using either kind of PM. A current sensitive preamplifier stage with individual gain adjustment interfaces the multi-anode PM outputs with a current division resistor network. The preamplifier stage allows to improve front-end processing delay and temporal resolution behavior as well as to increase impact position calculation resolution. Depth of interaction (DOI) is calculated from the width of the scintillation light distribution, which is related to the sum of voltages in resistor network input nodes. This operation is done by means of a high-speed current mode scheme.

Herrero, Vicente; Colom, Ricardo; Gadea, Rafael; Lerche, Christoph W.; Cerdá, Joaquín; Sebastiá, Ángel; Benlloch, José M.

2007-06-01

411

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

PubMed

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

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

2013-03-01

412

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

413

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.

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

2010-01-01

414

Inhibition of the cardiac inward rectifier potassium currents by KB-R7943.  

PubMed

KB-R7943 (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea) was developed as a specific inhibitor of the sarcolemmal sodium-calcium exchanger (NCX) with potential experimental and therapeutic use. However, KB-R7943 is shown to be a potent blocker of several ion currents including inward and delayed rectifier K(+) currents of cardiomyocytes. To further characterize KB-R7943 as a blocker of the cardiac inward rectifiers we compared KB-R7943 sensitivity of the background inward rectifier (IK1) and the carbacholine-induced inward rectifier (IKACh) currents in mammalian (Rattus norvegicus; rat) and fish (Carassius carassius; crucian carp) cardiac myocytes. The basal IK1 of ventricular myocytes was blocked with apparent IC50-values of 4.6×10(-6)M and 3.5×10(-6)M for rat and fish, respectively. IKACh was almost an order of magnitude more sensitive to KB-R7943 than IK1 with IC50-values of 6.2×10(-7)M for rat and 2.5×10(-7)M for fish. The fish cardiac NCX current was half-maximally blocked at the concentration of 1.9-3×10(-6)M in both forward and reversed mode of operation. Thus, the sensitivity of three cardiac currents to KB-R7943 block increases in the order IK1~INCXrectifier potassium currents, in particular IKACh, should be taken into account when interpreting the data with this inhibitor from in vivo and in vitro experiments in both mammalian and fish models. PMID:23973826

Abramochkin, Denis V; Alekseeva, Eugenia I; Vornanen, Matti

2013-08-22

415

Properties of Two Outward-Rectifying Channels in Root Xylem Parenchyma Cells Suggest a Role in K+ Homeostasis and Long-Distance Signaling.  

PubMed Central

Xylem parenchyma cells (XPCs) control the composition of the transpiration stream in plants and are thought to play a role in long-distance signaling as well. We addressed the regulation, selectivity, and dependence on the apoplastic ion concentrations of two types of outward rectifiers in the plasma membrane of XPCs, to assess the physiological role of these conductances. In whole-cell recordings, the membrane conductance at depolarization was under the control of cytosolic Ca2+: at physiological Ca2+ levels (150 nM) the K+ outward-rectifying conductance (KORC) predominated, whereas at elevated Ca2+ levels (5 [mu]M), only the nonselective outward-rectifying conductance (NORC) was active. No such regulatory effect of Ca2+ was observed in inside-out experiments. The voltage dependence of whole-cell KORC currents strongly depended on apoplastic K+ concentration: an increase in apoplastic K+ resulted in a positive shift of the current-voltage curve, roughly following the shift in Nernst potential of K+. KORC is impermeable to Na+, but does translocate Ca2+ in addition to K+. In contrast to KORC, NORC selected poorly among monovalent cations and anions, the relative permeability PC+/PA- being about 1.9. Gating of NORC was largely unaffected by the level of K+ in the bath. Under all ionic conditions tested, NORC tail currents or single-channel currents reversed close to 0 mV. Using an in vivo xylem-perfusion technique, tetraethylammonium (an inhibitor of KORC) was shown to block K+ transport to the shoot. These data support the hypothesis that release of K+ to the xylem sap is mediated by KORC. The molecular properties of these two conductances are discussed in the light of the distinct physiological role of XPCs.

Wegner, L. H.; De Boer, A. H.

1997-01-01

416

Production of electronic grade lunar silicon by disproportionation of silicon difluoride  

NASA Astrophysics Data System (ADS)

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

Agosto, William N.

1993-03-01

417

Silicon microdosimetry.  

PubMed

Silicon detectors are being studied as microdosemeters since they can provide sensitive volumes of micrometric dimensions. They can be applied for assessing single-event effects in electronic instrumentation exposed to complex fields around high-energy accelerators or in space missions. When coupled to tissue-equivalent converters, they can be used for measuring the quality of radiation therapy beams or for dosimetry. The use of micrometric volumes avoids the contribution of wall effects to the measured spectra. Further advantages of such detectors are their compactness, cheapness, transportability and a low sensitivity to vibrations. The following problems need to be solved when silicon devices are used for microdosimetry: (i) the sensitive volume has to be confined in a region of well-known dimensions; (ii) the electric noise limits the minimum detectable energy; (iii) corrections for tissue-equivalency should be made; (iv) corrections for shape equivalency should be made when referring to a spherical simulated site of tissue; (v) the angular response should be evaluated carefully; (vi) the efficiency of a single detector of micrometric dimensions is very poor and detector arrays should be considered. Several devices have been proposed as silicon microdosemeters, based on different technologies (telescope detectors, silicon on insulator detectors and arrays of cylindrical p-n junctions with internal amplification), in order to satisfy the issues mentioned above. PMID:21112892

Agosteo, Stefano; Pola, Andrea

2010-11-25

418

Uniform near-field nanopatterning due to the field distribution control by oblique femtosecond laser irradiation to silicon and gold nanoparticles  

Microsoft Academic Search

We present near-field optical properties around silicon and gold nanoparticles aligned on a silicon substrate excited by oblique incidence femtosecond laser for nanohole processing. Near-field nanofabrication will open up smart applications for new optical devices with high-throughput processing. The near field around silicon and gold particles is explained by Mie scattering theory, while the near field around gold nanoparticles is

Tomoya Miyanishi; Mitsuhiro Terakawa; Minoru Obara

2011-01-01

419

Advances in the understanding of low molecular weight silicon formation and implications for control by AMC filters  

NASA Astrophysics Data System (ADS)

Trimethylsilanol (TMS) is a low molecular weight / low boiling point silicon-containing, airborne contaminant that has received increased interest over the past few years as an important cause for contamination of optical surfaces in lithography equipment. TMS is not captured well by carbon-based filters, and hexamethyldisiloxane (HMDSO), even though captured well, can be converted to TMS when using acidic filter media commonly used for ammonia removal. TMS and HMDSO co-exist in a chemical equilibrium, which is affected by the acidity and moisture of their environment. This publication shows that HMDSO is converted to TMS by acidic media at concentrations typically found in cleanroom environments. This is contrary to published results that show a re-combination of TMS to HMDSO on acid media. We also demonstrate that, based on its conversion to TMS, HMDSO is not a suitable test compound for hybrid chemical filter performance, as the apparent lifetime/capacity of the filter can be substantially skewed towards larger numbers when conversion to TMS is involved. We show lifetime test results with toluene and HMDSO on acidic and non-acidic filter media. Appropriately designed, asymmetric hybrid chemical filters significantly minimize or eliminate the conversion of HMDSO to TMS, thereby reducing the risk to scanner optical elements. Similarly, such filters can also prevent or reduce acid-sensitive reactions of other AMC when passing through filter systems.

Lobert, Jürgen M.; Cate, Philip W.; Ruede, David J.; Wildgoose, Joseph R.; Miller, Charles M.; Gaudreau, John C.

2010-03-01

420

Control of Nitrogen Depth Profile and Chemical Bonding State in Silicon Oxynitride Films Formed by Radical Nitridation  

NASA Astrophysics Data System (ADS)

Chemical bonding states and depth profiles of nitrogen in radical nitrided silicon oxide film formed in Ar/N2 plasma excited by microwave has been investigated using X-ray photoelectron spectroscopy with HF step etching. The main chemical bonding state of nitrogen atom is Si3\\equivN configuration, and the other unknown bonding state (termed Nhigh) is observed, whose peak energy shift is about +4.8 eV. The nitrogen atoms forming Si3\\equivN configuration accumulate only at the film surface and those forming Nhigh configuration are distributed deeper in the films. The Nhigh bond is very weak because it is desorbed completely at low temperature (300-500°C). Although the nitrogen atoms forming Nhigh configuration are removed by post O2-annealing, those forming Si3\\equivN configuration migrate toward the film/substrate interface and they increase negative bias temperature instability. In the case of ultra thin film, nitriding species forming Nhigh bond reach the film/substrate interface and form Si3\\equivN bond at the interface. Suppression of the generation of nitriding species forming Nhigh bond in the plasma is very important. It is clear that Nhigh bond is reduced using Ar/NH3 plasma.

Kawase, Kazumasa; Umeda, Hiroshi; Inoue, Masao; Tsujikawa, Shimpei; Akamatsu, Yasuhiko; Suwa, Tomoyuki; Higuchi, Masaaki; Komura, Masanori; Teramoto, Akinobu; Ohmi, Tadahiro

2005-10-01

421

Atmospheric pressure plasma induced grafting of poly(ethylene glycol) onto silicone elastomers for controlling biological response.  

PubMed

This study investigates the role that surface functionalisation of silicone elastomer (SE) by atmospheric pressure plasma induced graft immobilisation of poly(ethylene glycol) methyl ether methacrylate (PEGMA) plays in the attendant biological response. SE is used in modern ophthalmic medical devices and samples of the material were initially plasma treated using a dielectric barrier discharge reactor (DBD) to introduce reactive oxygen functionalities, prior to in situ grafting of two molecular weights of PEGMA (MW 1000 Da: PEGMA(1000), MW 2000 Da: PEGMA(2000)). The variously processed surfaces were characterised by water contact angle analysis, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and atomic force microscopy. Lens epithelial cells were then cultured on the PEGMA grafted SE surfaces. It was found that cells on the pristine surface were not well spread and had shrunken morphology. On the DBD pre-treated surfaces, the cells were well spread. On the PEGMA(1000) surface, the cells displayed evidence of shrinkage and were on the verge of detaching. Remarkably, on the PEGMA(2000) surface, no cell adhesion was detection. Bacterial adhesion to the surfaces was studied using Staphylococcus aureus NTC8325. There was no difference in the number of bacteria adhering to any of the surfaces studied. PMID:22429588

D'Sa, Raechelle A; Raj, Jog; McMahon, M Ann S; McDowell, David A; Burke, George A; Meenan, Brian J

2012-03-03

422

Combination of iCVD and Porous Silicon for the Development of a Controlled Drug Delivery System.  

PubMed

We describe a pH responsive drug delivery system which was fabricated using a novel approach to functionalize biodegradeable porous silicon (pSi) by initiated chemical vapor deposition (iCVD). The assembly involved first loading a model drug (camptothecin, CPT) into the pores of the pSi matrix followed by capping the pores with a thin pH responsive copolymer film of poly(methacrylic acid-co-ethylene dimethacrylate) (p(MAA-co-EDMA)) via iCVD. Release of CPT from uncoated pSi was identical in two buffers at pH 1.8 and pH 7.4. In contrast, the linear release rate of CPT from the pSi matrix with the p(MAA-co-EDMA) coating was dependent on the pH; release of CPT was more than four times faster at pH 7.4 (13.1 nmol/(cm(2) h)) than at pH 1.8 (3.0 nmol/(cm(2) h)). The key advantage of this drug delivery approach over existing ones based on pSi is that the iCVD coating can be applied to the pSi matrix after drug loading without degradation of the drug because the process does not expose the drug to harmful solvents or high temperatures and is independent of the surface chemistry and pore size of the nanoporous matrix. PMID:22720638

McInnes, Steven J P; Szili, Endre J; Al-Bataineh, Sameer A; Xu, Jingjing; Alf, Mahriah E; Gleason, Karen K; Short, Robert D; Voelcker, Nicolas H

2012-06-21

423

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

Microsoft Academic Search

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

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

2003-01-01

424

Positive Temperature Coefficient of Breakdown Voltage in 4H-SiC PN junction Rectifiers.  

National Technical Information Service (NTIS)

It has been suggested that once silicon carbide (SiC) technology overcomes some crystal growth obstades, superior SiC semiconductor devices will supplant silicon in many high power applications. However, a positive temperature coefficient of breakdown vol...

P. G. Neudeck C. Fazi

1998-01-01

425

A four level rectifier inverter system for drive applications  

Microsoft Academic Search

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

G. Sinha; T.A. Lipo

1998-01-01

426

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

PubMed

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. PMID:22418779

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

2012-03-14

427

A High Power Density Single-Phase PWM Rectifier With Active Ripple Energy Storage  

SciTech Connect

It is well known that single-phase pulse width modulation rectifiers have second-order harmonic currents and corresponding ripple voltages on the dc bus. The low-frequency harmonic current is normally filtered using a bulk capacitor in the bus, which results in low power density. However, pursuing high power density in converter design is a very important goal in the aerospace applications. This paper studies methods for reducing the energy storage capacitor for single-phase rectifiers. The minimum ripple energy storage requirement is derived independently of a specific topology. Based on theminimum ripple energy requirement, the feasibility of the active capacitor s reduction schemes is verified. Then, we propose a bidirectional buck boost converter as the ripple energy storage circuit, which can effectively reduce the energy storage capacitance. The analysis and design are validated by simulation and experimental results.

Wang, Ruxi [Virginia Polytechnic Institute and State University (Virginia Tech); Wang, Fei [ORNL; Boroyevich, Dushan [Virginia Polytechnic Institute and State University (Virginia Tech); Burgos, Rolando [ABB; Lai, Rixin [General Electric; Ning, Puqi [ORNL; Rajashekara, Kaushik [Rolls Royce

2011-01-01

428

Stable few-layer MoS2 rectifying diodes formed by plasma-assisted doping  

NASA Astrophysics Data System (ADS)

We present a method for making stable MoS2 rectifying diodes using selected-area plasma treatment. The transport and X-ray photoelectron spectroscopic characterizations of MoS2 transistors treated with different plasmas confirm that the rectifying characteristics of MoS2 diodes are attributed to plasma-induced p-doping and p-n junctions in MoS2. Such plasma-doped diodes exhibit high forward/reverse current ratios (~104 for SF6-treated diodes) and a superior long-term stability. They can play an important role in the development of nanoelectronic devices. In addition, the presented plasma-assisted doping process could be also used for making ambipolar MoS2 transistors and functionalizing other emerging two-dimensional materials.

Chen, Mikai; Nam, Hongsuk; Wi, Sungjin; Ji, Lian; Ren, Xin; Bian, Lifeng; Lu, Shulong; Liang, Xiaogan

2013-09-01

429

High performance ripple feedback for the buck unity-power-factor rectifier  

SciTech Connect

The buck unity-power-factor rectifier has harmonic-free input current with complete load regulation down to zero output voltage. A new ``nonlinear ripple feedback`` is proposed which exactly cancels the spoiling effect of dc-side current ripple on the low-distortion ac line current waveforms, even for large amounts of ripple. This cancellation is independent of operating point and readily implemented with analog hardware, thereby permitting economies in the design of the dc filter while maintaining harmonic-free operation. Both large-signal and incremental analyses of the rectifier are given. Confirming experimental results from a 1-kW 48-V isolated battery charger operating with current-ripple levels ranging from 50% to discontinuous-conduction-mode operation are given.

Lo, Y.W.; King, R.J. [Univ. of Toledo, OH (United States). Dept. of Electrical Engineering

1995-03-01

430

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

431

Silicon Carbide Matrix Composites.  

National Technical Information Service (NTIS)

The latest development for silicon carbide/silicon carbide and carbon/silicon carbide composites are presented. These composites are obtained by processes based on infiltration, and pyrolysis of organometallic materials. Ceramic matrix composites are prom...

P. Pernot P. Lespade M. Parlier

1992-01-01

432

Minerals Yearbook, 1990: Silicon.  

National Technical Information Service (NTIS)

Silicon (Si) is a light chemical element with both metallic and nonmetallic characteristics. In nature, silicon combines with oxygen and other elements to form silicates. Silicon in the form of silicates constitutes more than 25% of the Earth's crust. Sil...

J. Gambogi

1990-01-01

433

Control of optical bandgap energy and optical absorption coefficient by geometric parameters in sub-10 nm silicon-nanodisc array structure  

NASA Astrophysics Data System (ADS)

A sub-10 nm, high-density, periodic silicon-nanodisc (Si-ND) array has been fabricated using a new top-down process, which involves a 2D array bio-template etching mask made of Listeria-Dps with a 4.5 nm diameter iron oxide core and damage-free neutral-beam etching (Si-ND diameter: 6.4 nm). An Si-ND array with an SiO2 matrix demonstrated more controllable optical bandgap energy due to the fine tunability of the Si-ND thickness and diameter. Unlike the case of shrinking Si-ND thickness, the case of shrinking Si-ND diameter simultaneously increased the optical absorption coefficient and the optical bandgap energy. The optical absorption coefficient became higher due to the decrease in the center-to-center distance of NDs to enhance wavefunction coupling. This means that our 6 nm diameter Si-ND structure can satisfy the strict requirements of optical bandgap energy control and high absorption coefficient for achieving realistic Si quantum dot solar cells.

Fairuz Budiman, Mohd; Hu, Weiguo; Igarashi, Makoto; Tsukamoto, Rikako; Isoda, Taiga; Itoh, Kohei M.; Yamashita, Ichiro; Murayama, Akihiro; Okada, Yoshitaka; Samukawa, Seiji

2012-02-01

434

Harmonic Torque and Speed Pulsations in a Rectifier-Inverter Induction Motor Drive  

Microsoft Academic Search

A method of predicting the 6th-harmonic electromagnetic torque of an induction motor arising from a rectifier-inverter power source is presented. This study includes both the effects of harmonic variation rotor speed and inverter voltage. Although only the 6th harmonic is considered, it is shown that this is sufficiently accurate to predict steady-state system performance for practical speed ranges and system

Thomas Lipo; Paul Krause; Howard Jordan

1969-01-01

435

Ceramide Inhibits the Inwardly Rectifying Potassium Current in GH3 Lactotrophs  

Microsoft Academic Search

The effects of ceramide on ion currents in rat pituitary GH3 cells were investigated. Hyperpolarization-elicited K cur- rents present in GH3 cells were studied to determine the effect of ceramide and other related compounds on the inwardly rectifying K current (IK(IR)). Ceramide (C2-ceramide) sup- pressed the amplitude of IK(IR) in a concentration-dependent manner, with an IC50 value of 5 M.

SHENG-NAN WU; YUK-KEUNG LO; BENJAMIN ING-TIAU KUO; HUNG-TING CHIANG

2001-01-01

436

Performance of low loss synchronous rectifiers in a series-parallel resonant DC-DC converter  

Microsoft Academic Search

The functionality of efficient synchronous rectifier components, specially developed for resonant DC-DC converter topologies designed to operate at high frequency, has been demonstrated in a series-parallel converter circuit operating at 420 kHz and 85 W. Conduction losses for these components are three times lower than for Schottky diodes. Switching conditions for efficient operation have been identified both experimentally and using

R. A. Fisher; C. S. Korman; G. A. Franz; G. W. Ludwig; J. P. Walden; S. A. El-Hamamsy; K. Shenai; M. Kuo

1989-01-01

437

Inwardly rectifying K + channels in the basolateral membrane of rat pancreatic acini  

Microsoft Academic Search

Previous studies of the whole-cell K+ conductance suggest the presence of inwardly rectifying K+ channels (Kir) in rat pancreatic acini (RPAs). Here we investigate the properties of Kir of RPAs using patch-clamp techniques. The whole-cell current-to-voltage relationship of freshly isolated RPAs was steeper for inward currents than for outward currents when the extracellular K+ concentration ([K+]o) was raised. With a

Sung Joon Kim; Gunter Kerst; Rainer Schreiber; Hermann Pavenstädt; Rainer Greger; Martin J. Hug; Markus Bleich

2000-01-01

438

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

439

Simulation and modeling for soft recovery of p-i-n rectifiers  

Microsoft Academic Search

Soft recovery of fast-switching p-i-n rectifiers is studied using experimental data and a novel coupled device and circuit simulator. An analytical model for determining lifetimes is presented and verified by numerical simulations. The softness factor is difficult to model analytically; hence simulations are necessary. Coupled device and circuit simulations also allow a determination of the magnitude of the inductive voltage

K. Mayaram; B. Tien; C. Hu; D. O. Pederson

1988-01-01

440

Comparison of GaN p-i-n and Schottky rectifier performance  

Microsoft Academic Search

The performance of GaN p-i-n and Schottky rectifiers fabricated on the same wafer was investigated as a function of device size and operating temperature. There was a significant difference in reverse breakdown voltage (490 V for p-i-n diodes; 347 V for the Schottky diodes) and forward turn-on voltage (~5 V for the p-i-n diodes; ~3.5 V for the Schottky diodes).

A. P. Zhan; Gerard T. Dang; Fan Ren; Hyun Cho; Kyu-Pil Lee; Stephen J. Pearton; Jenn-Inn Chyi; T.-Y. Nee; C.-C. Chuo

2001-01-01

441

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

442

Opposing Effects of Aluminum on Inward-Rectifier Potassium Currents in BeanRoot-Tip Protoplasts  

Microsoft Academic Search

Inward currents in root cap protoplasts of the aluminum-tolerant cultivar, Dade, of Phaseolus vulgaris L. were investigated using the whole-cell patch-clamp technique. The properties of these currents were similar to those seen in inward rectifying K+ channels in other plant tissues. Replacing bath K+ with Na+ nearly abolished the observed currents. Higher bath K+ concentrations increased inward currents. AlCl3 in

B. Etherton; T. J. Heppner; J. R. Cumming; M. T. Nelson

2004-01-01

443

Status of the techniques of three-phase rectifier systems with low effects on the mains  

Microsoft Academic Search

Based on a comprehensive study of the literature, concepts of three-phase rectifier systems with low effects on the mains are classified. Such systems are unidirectional and bidirectional self-commutated power converters with impressed output voltage or output current and line-commutated rectification in connection with passive and active filtering. Selected circuit concepts are analyzed concerning the operational behavior and the obtainable quality

J. W. Kolar; Hans Ertl

1999-01-01

444

ANALYSIS OF COMMON-MODE VOLTAGE IN DIODE RECTIFIER\\/Z- SOURCE INVERTER SYSTEM  

Microsoft Academic Search

In this paper, the common-mode voltage (CMV) of diode rectifier\\/Z-source inverter system is analyzed in detail under shoot-through state and non-shoot-through state. Then, two simple algorithms are proposed to reduce both negative and positive CMV. Herein, the negative CMV is effectively mitigated by using a modified space vector modulation (MSVM) strategy without V0. By eliminating zero-voltage vector (ZVV) V0, the

Quang-Vinh Tran; Tae-Won Chun; Jung-Jyol Ahn; Hong-Hee Lee

2007-01-01

445

Modeling a Hybrid Diode-Thyristor HVDC Rectifier in EMTP-RV  

Microsoft Academic Search

This paper presents the investigation into the viability of a hybrid diode-thyristor high voltage direct current (HVDC) rectifier. The large-scale usage of HVDC transmission is limited by several factors and one of the most important factors is the high cost of conversion equipment. In a traditional HVDC system, a 12-pulse thyristor converter is used. In the proposed hybrid circuit, the

N. Monsur; Vijay Kumar Sood; L. Lopes

2006-01-01

446

Expression of G-protein inwardly rectifying potassium channels (GIRKs) in lung cancer cell lines  

Microsoft Academic Search

BACKGROUND: Previous data from our laboratory has indicated that there is a functional link between the ?-adrenergic receptor signaling pathway and the G-protein inwardly rectifying potassium channel (GIRK1) in human breast cancer cell lines. We wanted to determine if GIRK channels were expressed in lung cancers and if a similar link exists in lung cancer. METHODS: GIRK1-4 expression and levels

Howard K Plummer III; Madhu S Dhar; Maria Cekanova; Hildegard M Schuller

2005-01-01

447

Rutaecarpine-induced block of delayed rectifier K + current in NG108-15 neuronal cells  

Microsoft Academic Search

The effects of rutaecarpine on ionic currents of NG108-15 neuronal cells were investigated in this study. Rutaecarpine (2–100 ?M) suppressed the amplitude of delayed rectifier K+ current (IK(DR)) in a concentration-dependent manner. The IC50 value for rutaecarpine-induced inhibition of IK(DR) was 11 ?M. IK(DR) present in these cells is sensitive to the inhibition by quinidine and dendrotoxin, yet not by

Sheng-Nan Wu; Yuk-Keung Lo; Hsinyo Chen; Hui-Fang Li; Hung-Ting Chiang

2001-01-01

448

Nootropic agent vinpocetine blocks delayed rectified potassium currents more strongly than high-threshold calcium currents  

Microsoft Academic Search

A two-microelectrode potential clamping method was used on isolated common snail neurons to measure high-threshold Ca2+ and delayed rectified K+ currents. Addition of the nootropic agent vinpocetine (VPC) to the bathing solution rapidly and reversibly inhibited both\\u000a types of current. The effects of VPC were dosedependent and were independent of the test stimulus voltage. Maximum blockade\\u000a of the Ca2+ current

Yu. V. Bukanova; E. I. Solntseva

1998-01-01

449

Modulation of delayed rectifier K + channel activity by external K + ions in Xenopus axon  

Microsoft Academic Search

The effect of external K+ ions upon the activation of delayed rectifier K+ channels was studied in demyelinated amphibian nerve fibres by means of the patch-clamp technique. In external 105 mM K+ solution (high-Ko) macroscopic K+ currents activated at more negative potentials (??15 mV) than in external Ringer (2.5 mM K+). Since the rapid substitution of external Ringer with high-Ko

Boris V. Safronov; Werner Vogel

1995-01-01

450

Molecular Mechanisms Mediating Inhibition of G Protein-coupled Inwardly-rectifying K+ Channels  

Microsoft Academic Search

Neuronal G protein-coupled inwardly-rectifying po- tassium channels (GIRKs, Kir3.x) can be activated or inhibited by distinct classes of receptors (G?i\\/o and G?q\\/11-coupled, respectively), providing dynamic regulation of neuronal excitability.In this mini-review, we highlight findings from our laboratory in which we used a mammalian heterologous expression system to address mechanisms of GIRK channel regulation by G? and G?? subunits.We found that,

Qiubo Lei; Miller B. Jones; Edmund M. Talley; James C. Garrison; Douglas A. Bayliss

451

Inhibition of G Protein-Activated Inwardly Rectifying K+ Channels by Ifenprodil  

Microsoft Academic Search

G protein-activated inwardly rectifying K+ channels (GIRK, also known as Kir3) are regulated by various G-protein-coupled receptors. Activation of GIRK channels plays an important role in reducing neuronal excitability in most brain regions and the heart rate. Ifenprodil, which is a clinically used cerebral vasodilator, interacts with several receptors, such as ?1 adrenergic, N-methyl-D-aspartate, serotonin and ? receptors. However, the

Toru Kobayashi; Kazuo Washiyama; Kazutaka Ikeda

2006-01-01

452

Operating limits of the current-regulated delta-modulated current-source PWM rectifier  

Microsoft Academic Search

A stand alone, three-phase, delta-modulated, current-source PWM rectifier has been built and has been shown to be capable of operating with near sinusoidal current waveforms, unity power factor. and good DC current regulation. A mathematical model that has been justified against experimental measurements and results from digital simulations is presented. The current waveform distortion limit and the asymptotic stability limit

Boon Teck Ooi; Bakari M. M. Mwinyiwiwa; Xiao Wang; Geza Joos

1991-01-01

453

Cardiac Purkinje fibers: Cesium as a tool to block inward rectifying potassium currents  

Microsoft Academic Search

Summary When a cardiac Purkinje fiber is exposed to 20 mM Cs the membrane potential falls to about -60 mV within 1 min. In voltage clamp experiments, exposure to Cs blocks both the pacemaker currentiK2 and the instantaneous outward currentiK2, while the delayed outward rectifying potassium currentix is not affected. In the presence of 20 mM Cs, the steady state

G. Isenberg

1976-01-01

454

Expression of inwardly rectifying potassium channel subunits in native human retinal pigment epithelium  

Microsoft Academic Search

Previously, we demonstrated that the inwardly rectifying K+ (Kir) channel subunit Kir7.1 is highly expressed in bovine and human retinal pigment epithelium (RPE). The purpose of this study was to determine whether any of the 14 other members of the Kir gene family are expressed in native human RPE. Conventional reverse transcription-polymerase chain reaction (RT-PCR) analysis indicated that in addition

Dongli Yang; Xiaoming Zhang; Bret A. Hughes

2008-01-01

455

Proposal of rectifier type superconducting fault current limiter with non-inductive reactor (SFCL)  

Microsoft Academic Search

A rectifier type superconducting fault current limiter (SFCL) with non-inductive reactor has been proposed. The concept behind this SFCL is the appearance of high impedance during non-superconducting state of the coil. In a hybrid bridge circuit, two superconducting coils connected in anti-parallel: a trigger coil and a limiting coil. Both the coils are magnetically coupled with each other and have

Khosru Mohammad Salim; Itsuya Muta; Tsutomu Hoshino; Taketsune Nakamura; Masato Yamada

2004-01-01

456

First results on real-time quality control and dosimetry of ? emitting sources used in medical applications using Silicon strip detectors  

Microsoft Academic Search

Real-time dosimetry is a critical issue in most radiotherapy applications. SUCIMA (Proceedings of the Eighth Topical Seminar on Innovative Particle and Radiation Detectors, Siena, Italy) (Silicon Ultra fast Cameras for electron and gamma sources in Medical Applications) is an EC project addressing the development of an imaging device for extended radioactive sources based on monolithic and hybrid position sensitive silicon

C. Cappellini; A. Airoldi; M. Alemi; M. Amati; C. Bianchi; A. Bulgheroni; M. Caccia; L. Conte; W. Kucewicz; M. Prest; E. Vallazza; C. Sampietro

2004-01-01

457

Research on dual-stator winding multi-phase high-speed induction generator with rectifier load  

Microsoft Academic Search

Based on analysis and calculation of the relation between current harmonics and MMF harmonics in the dual-stator winding multi-phase\\u000a high-speed induction generator with a rectifier load, a new idea, which divides the generator system into two sub-systems\\u000a to be analyzed individually, is presented. For the sub-system of the 12-phase power winding with a rectifier load, the loop\\u000a current method is

XiangHeng Wang; XinZhen Wu

2008-01-01

458

Time-dependent Outward Currents through the Inward Rectifier Potassium Channel IRK1 . The Role of Weak Blocking Molecules  

Microsoft Academic Search

Outward currents through the inward rectifier K 1 channel contribute to repolarization of the car- diac action potential. The properties of the IRK1 channel expressed in murine fibroblast (L) cells closely resem- ble those of the native cardiac inward rectifier. In this study, we added Mg 2 1 (0.44-1.1 mM) or putrescine ( z 0.4 mM) to the intracellular milieu

Keiko Ishihara

1997-01-01

459

A tetraethylammonium-insensitive inward rectifier K + channel in müller cells of the turtle ( Pseudemys scripta elegans ) retina  

Microsoft Academic Search

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

A. C. Le Dain; P. J. Anderton; D. K. Martin; T. J. Millar

1994-01-01

460

The G-protein-gated atrial K+ channel IKAch is a heteromultimer of two inwardly rectifying K+-channel proteins  

Microsoft Academic Search

Heart rate is slowed in part by acetylcholine-dependent activation of a cardiac potassium (K+) channel, IKACh. Activated muscarinic receptors stimulate lKAch via the G-protein betagamma-subunits. It has been assumed that the inwardly rectifying K+-channel gene, GIRK1, alone encodes IKAch-It is now shown that IKAch is a heteromultimer of two distinct inwardly rectifying K+-channel subunits, GIRK1 and a newly cloned member

G. Krapivinsky; E. A. Gordon; K. Wickman; B. Velimirovic; L. Krapivinsky; D. E. Clapham

1995-01-01

461

Effect of temperature on rectifying Schottky barriers formed from fingerprint sweat corrosion of brass.  

PubMed

Corrosive electrochemical processes of brass, including those resulting from fingerprint sweat, continue to be studied because of the widespread industrial use of brass. Here, we examine how increased temperature affects the relative abundance of fingerprint sweat corrosion products and the rectifying Schottky barrier formed between p-type copper (I) oxide corrosion and brass. X-ray photoelectron spectroscopy confirms increasing dezincification with increasing temperature. This leads to n-type zinc oxide replacing copper (I) oxide as the dominant corrosion product, which then forms a rectifying Schottky barrier with the brass, instead of copper oxide, when the temperature reaches c. 600°C. Using X-ray diffraction, resulting diodes show polycrystalline oxides embedded in amorphous oxidation products that have a lower relative abundance than the diode forming oxide. Conventional current/voltage (I/V) characteristics of these diodes show good rectifying qualities. At temperatures between c. 100 and c. 600°C, when neither oxide dominates, the semiconductor/brass contact displays an absence of rectification. PMID:21595693

Bond, John W

2011-05-19

462

[Silicone molding compounds and latex gloves. The effect of latex gloves on addition and condensation silicones].  

PubMed

Inhibited setting of addition silicones has been observed using latex gloves in the dental office. Therefore four addition silicones as well as four condensation silicones were mixed with seven latex gloves with different properties (sterility, powder, accelerator, inner layer). The masses were mixed with bare hands as a control and--additionally--with powdered hands. Condensation silicones stayed unaffected when put together in exact amounts, while some addition silicones showed nearly complete inhibition. Mixing the condensation silicones under the conditions of daily practice--one spoon of body plus a distinct amount of catalyst-resulted in hardness differences compared to using the exact dose. Nevertheless the resulting impressions were of satisfying quality. The powder-component (Bio-sorb, Surgikos) leads to an accelerated setting. The general dental practitioner/dental hygienist have to consider these aspects while choosing gloves and silicone putties for taking impressions. PMID:1626265

Baumann, M A; Klapper, M

1992-01-01

463

Methanol steam reformer on a silicon wafer  

Microsoft Academic Search

A study of the reforming rates, heat transfer and flow through a methanol reforming catalytic microreactor fabricated on a silicon wafer are presented. Packed bed microchannel reactors were fabricated using silicon DRIE, followed by wafer bonding. The reactor bed was subsequently filled with catalyst particles. Thermal control is achieved through on-chip resistive heaters, whereby methanol steam reforming reactions were studied

Hyung Gyu Park; Jonathan A. Malen; W. Thomas Piggott; Jeffrey D. Morse; Ralph Greif; Costas P. Grigoropoulos; Mark A. Havstad; Ravi Upadhye

2006-01-01

464

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

465

Silicon Nanocrystal Synthesis in Microplasma Reactor  

NASA Astrophysics Data System (ADS)

Nanocrystalline silicon particles with grains smaller than 5 nm are widely recognized as a key material in optoelectronic devices, lithium battery electrodes, and bio-medical labels. Another important characteristic is that silicon is an environmentally safe material that is used in numerous silicon technologies. To date, several synthesis methods such as sputtering, laser ablation, and plasma-enhanced chemical vapor deposition (PECVD) based on low-pressure silane chemistry (SiH4) have been developed for precise control of size and density distributions of silicon nanocrystals. In this study, we explore the possibility of microplasma technologies for efficient production of mono-dispersed nanocrystalline silicon particles on a micrometer-scale, continuous-flow plasma reactor operated at atmospheric pressure. Mixtures of argon, hydrogen, and silicon tetrachloride were activated using a very-high-frequency (144 MHz) power source in a capillary glass tube with volume of less than 1 ?l. Fundamental plasma parameters of the microplasma were characterized using optical emission spectroscopy, which respectively indicated electron density of 1015 cm-3, argon excitation temperature of 5000 K, and rotational temperature of 1500 K. Such high-density non-thermal reactive plasma can decompose silicon tetrachloride into atomic silicon to produce supersaturated silicon vapor, followed by gas-phase nucleation via three-body collision: particle synthesis in high-density plasma media is beneficial for promoting nucleation processes. In addition, further growth of silicon nuclei can be terminated in a short-residence-time reactor. Micro-Raman scattering spectra showed that as-deposited particles are mostly amorphous silicon with a small fraction of silicon nanocrystals. Transmission electron micrography confirmed individual 3-15 nm silicon nanocrystals. Although particles were not mono-dispersed, they were well separated and not coagulated.

Nozaki, Tomohiro; Sasaki, Kenji; Ogino, Tomohisa; Asahi, Daisuke; Okazaki, Ken

466

Synthesis of Silicon Nanocrystals in Microplasma Reactor  

NASA Astrophysics Data System (ADS)

Nanocrystalline silicon particles with a grain size of at least less than 10 nm are widely recognized as one of the key materials in optoelectronic devices, electrodes of lithium battery, bio-medical labels. There is also important character that silicon is safe material to the environment and easily gets involved in existing silicon technologies. To date, several synthesis methods such as sputtering, laser ablation, and plasma enhanced chemical vapor deposition (PECVD) based on low-pressure silane chemistry (SiH4) have been developed for precise control of size and density distributions of silicon nanocrystals. We explore the possibility of microplasma technologies for the efficient production of mono-dispersed nanocrystalline silicon particles in a micrometer-scale, continuous-flow plasma reactor operated at atmospheric pressure. Mixtures of argon, hydrogen, and silicon tetrachloride were activated using very high frequency (VHF = 144 MHz) power source in a capillary glass tube with a volume of less than 1 ?-liter. Fundamental plasma parameters of VHF capacitively coupled microplasma were characterized by optical emission spectroscopy, showing electron density of approximately 1015 cm-3 and rotational temperature of 1500 K, respectively. Such high-density non-thermal reactive plasma has a capability of decomposing silicon tetrachloride into atomic silicon to produce supersaturated atomic silicon vapor, followed by gas phase nucleation via three-body collision. The particle synthesis in high-density plasma media is beneficial for promoting nucleation process. In addition, further growth of silicon nuclei was able to be favorably terminated in a short-residence time reactor. Micro Raman scattering spectrum showed that as-deposited particles were mostly amorphous silicon with small fraction of silicon nanocrystals. Transmission electron micrograph confirmed individual silicon nanocrystals of 3-15 nm size. Although those particles were not mono-dispersed, they were well separated and not coagulated.

Nozaki, Tomohiro; Sasaki, Kenji; Ogino, Tomohisa; Asahi, Daisuke; Okazaki, Ken

467

Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.  

PubMed

A new method of using photo-electromotive force in detecting gas and controlling sensitivity is proposed. Photo-electromotive force on the heterojunction between porous silicon thin layer and crystalline silicon wafer depends on the concentration of ammonia in the measurement chamber. A porous silicon thin layer was formed by electrochemical etching on p-type silicon wafer. A gas and light transparent electrical contact was manufactured to this porous layer. Photo-EMF sensitivity corresponding to ammonia concentration in the range from 10 ppm to 1,000 ppm can be maximized by controlling the intensity of illumination light. PMID:22319353

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-25

468

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

469

Superhydrophobic silicone fiber mats fabricated by electrospinning from solution  

Microsoft Academic Search

Fine silicone fibers of 1 -- 20 mum diameter were fabricated from solution via electrospinning. These are the first examples of fine fibers prepared from silicone homopolymers. Fiber morphology (beaded, ribbon-like, smooth) and diameter were controlled. The nanoscale surface roughness of nonwoven fiber mats created with silicone fibers produced a superhydrophobic surface that had a water contact angle of ˜160^o.

Bonnie Ludwig; Aneta Clark; Steven Snow; Randal Hill; Randall Schmidt; Brad Fogg; Peter Lo

2007-01-01

470

Porous silicon as a low dimensional and optical material  

Microsoft Academic Search

The considerable and controllable changes in electronic structure and refractive index of porous silicon fabricated by electrochemical anodization make it become a promising material for photonics in comparison with bulk silicon. As the study of PS in terms of a low-dimensional material, we reviewed the effect of the surface passivation of silicon nanocrystals on photoluminescence spectra of such zero-dimensional crystals.

Bui Huy; Pham Van Hoi; Phan Hong Khoi; Do Khanh Van; Pham Thanh Binh; Tran Thi Cham

2009-01-01

471

Silicon Investor  

NSDL National Science Digital Library

Silicon Investor, developed by go2net Inc., aims to "deliver timely, superior information" on the stock market. A team of stock analysts provide stock tips, market analysis, company reports, and breaking financial news. Additional features include commentaries on the marketplace, IPOs, earnings and government reports written by the site's regular columnists. The site also offers a portfolio tracker, an up-to-date list of stock splits, stock rating upgrades or downgrades, and an earnings calendar. Updates on the major market indices, yield curves and Reuters news can also be obtained at the site.

2000-01-01

472

Selective control of liver and kidney cells migration during organotypic cocultures inside fibronectin-coated rectangular silicone microchannels  

Microsoft Academic Search

In this work, the behaviors of embryonic liver and kidney explants were studied inside rectangular polydimethylsiloxane (PDMS) microchannels. The organs were cultured under monoculture and coculture conditions on PDMS coated with or without fibronectin. The results demonstrated that the migration of cells from both organs is dependent on culture conditions and thus can be selectively controlled. In liver monocultures without

Eric Leclerc; Régis Baudoin; Anne Corlu; Laurent Griscom; Jean Luc Duval; Cécile Legallais

2007-01-01

473

Process Control of Aluminum-Doped Silicon Deposited by Low-Temperature Material Inversion SolidPhase Epitaxy  

Microsoft Academic Search

This paper describes the experimental conditions leading to the selective growth of nanoscale single crystals where the location and dimensions are well controlled, even in the sub- 100 nm range. The position of the crystals is pre-defined by conventional lithography and the grown Si shows excellent electrical characteristics. Fifty-nanometer-thick p + SPE Si crystals were used to fabricate p +

Y. Civale; L. K. Nanver; P. Hadley

474

D0 Silicon Upgrade: D0 Central Tracking Solenoid: Specification for Solenoid Energization, controls, Interlocks and Quench Protection  

Microsoft Academic Search

This document has served as the specification for the energization, control, interlocking and quench protection systems for the DZERO superconducting solenoid installation. This does not include the cryogenics system. As the work proceeded, the details of the design were 'fleshed out' such that this document ultimately describes the system 'as built'. See 'Revisions to this document' for a description of

R. Hance; W. Jaskierney; S. Orr

1995-01-01

475

Impact of duty ratio-controlled ion energy on surface roughness of silicon nitride films deposited using a SiH4-NH3 plasma.  

PubMed

The impact of duty ratio-controlled ion energy on the surface roughness of silicon nitride (SiN) films is examined as a function of the bias power and the duty ratio. Experimental ranges are 30-90 W and 20-80% for the bias power and the duty ratio, respectively. SiN films were deposited at room temperature using a SiH4-NH3 pulsed plasma. Atomic force microscopy was used to measure surface roughness. Investigation is detailed in view of a mean-surface roughness, a non-uniformity of surface height distribution, and using a prediction model. The prediction model was constructed using a neural network and a genetic algorithm. A decrease in the duty ratio results in an increase in the surface roughness, but a decrease in the non-uniformity. Correlation study revealed that the surface roughness was strongly related to the ion energy and the ion energy flux. The neural network model predicts the high ion energy as the most influential diagnostic parameter. PMID:22121601

Kim, Daehyun; Lee, Hwajune; Kim, Byungwhan; Seo, Yong Ho; Yoon, Neung-Goo; Han, Dongil

2011-07-01

476

Expression and polarized distribution of an inwardly rectifying K+ channel, Kir4.1, in rat retinal pigment epithelium  

PubMed Central

In the eye, different substances and ions including potassium (K+) are transported between neural retina and choroid via the subretinal space. Inwardly rectifying K+ channels (Kir) on the apical membrane of retinal pigment epithelial (RPE) cells are thought to play an essential role in K+ transport in the subretinal space. Single-channel recordings from the apical membrane of RPE cells exhibited functional expression of a Kir channel with properties identical to those of Kir4.1, while recordings from the basolateral membrane showed no detectable Kir channel currents. The expression of Kir4.1 mRNA in RPE cells was confirmed by RT-PCR analysis and in situ hybridization. Furthermore, using immunohistochemistry, we found that Kir4.1 was prominently expressed in RPE cells and localized specifically on the processes on their apical membrane. Developmental studies revealed that expression of Kir4.1 started to appear 10 days or later after birth in RPE cells, in parallel with the maturation of retinal neuronal activity as represented by the a- and b-waves of the electroretinogram. These data suggest that Kir4.1 is one of the Kir channels involved in RPE-mediated control of K+ ions in the subretinal space.

Kusaka, Shunji; Horio, Yoshiyuki; Fujita, Akikazu; Matsushita, Kenji; Inanobe, Atsushi; Gotow, Takahiro; Uchiyama, Yasuo; Tano, Yasuo; Kurachi, Yoshihisa

1999-01-01

477

Eliciting Renal Failure in Mosquitoes with a Small-Molecule Inhibitor of Inward-Rectifying Potassium Channels  

PubMed Central

Mosquito-borne diseases such as malaria and dengue fever take a large toll on global health. The primary chemical agents used for controlling mosquitoes are insecticides that target the nervous system. However, the emergence of resistance in mosquito populations is reducing the efficacy of available insecticides. The development of new insecticides is therefore urgent. Here we show that VU573, a small-molecule inhibitor of mammalian inward-rectifying potassium (Kir) channels, inhibits a Kir channel cloned from the renal (Malpighian) tubules of Aedes aegypti (AeKir1). Injection of VU573 into the hemolymph of adult female mosquitoes (Ae. aegypti) disrupts the production and excretion of urine in a manner consistent with channel block of AeKir1 and renders the mosquitoes incapacitated (flightless or dead) within 24 hours. Moreover, the toxicity of VU573 in mosquitoes (Ae. aegypti) is exacerbated when hemolymph potassium levels are elevated, suggesting that Kir channels are essential for maintenance of whole-animal potassium homeostasis. Our study demonstrates that renal failure is a promising mechanism of action for killing mosquitoes, and motivates the discovery of selective small-molecule inhibitors of mosquito Kir channels for use as insecticides.

Raphemot, Rene; Rouhier, Matthew F.; Hopkins, Corey R.; Gogliotti, Rocco D.; Lovell, Kimberly M.; Hine, Rebecca M.; Ghosalkar, Dhairyasheel; Longo, Anthony; Beyenbach, Klaus W.; Denton, Jerod S.; Piermarini, Peter M.

2013-01-01

478

Semiconductor systems utilizing materials that form rectifying junctions in both N and P-type doping regions, whether metallurgically or field induced, and methods of use  

SciTech Connect

Disclosed are semiconductor systems, such as integrated circuits utilizing Schotky barrier and/or diffused junction technology, which semiconductor systems incorporate material(s) that form rectifying junctions in both metallurgically and/or field induced N and P-type doping regions, and methods of th