Noise Properties of Rectifying Nanopores

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

Powell, M R; Sa, N; Davenport, M

2011-02-18

Ion currents through three types of rectifying nanoporous structures are studied and compared for the first time: conically shaped polymer nanopores, glass nanopipettes, and silicon nitride nanopores. Time signals of ion currents are analyzed by power spectrum. We focus on the low-frequency range where the power spectrum magnitude scales with frequency, f, as 1/f. Glass nanopipettes and polymer nanopores exhibit non-equilibrium 1/f noise, thus the normalized power spectrum depends on the voltage polarity and magnitude. In contrast, 1/f noise in rectifying silicon nitride nanopores is of equilibrium character. Various mechanisms underlying the voltage-dependent 1/f noise are explored and discussed, includingmore » 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.« less

Noise Properties of Rectifying Nanopore

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

Vlassiouk, Ivan V

2011-01-01

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

A Novel Phase-Shift Control of Semibridgeless Active Rectifier for Wireless Power Transfer

DOE PAGES

Colak, Kerim; Asa, Erdem; Bojarski, Mariusz; ...

2015-05-12

We investigated a novel phase-shift control of a semibridgeless active rectifier (S-BAR) in order to utilize the S-BAR in wireless energy transfer applications. The standard receiver-side rectifier topology is developed by replacing rectifier lower diodes with synchronous switches controlled by a phase-shifted PWM signal. Moreover, theoretical and simulation results showthat with the proposed control technique, the output quantities can be regulated without communication between the receiver and transmitter. In order to confirm the performance of the proposed converter and control, experimental results are provided using 8-, 15-, and 23-cm air gap coreless transformer which has dimension of 76 cm xmore » 76 cm, with 120-V input and the output power range of 0 to 1kW with a maximum efficiency of 94.4%.« less

Modelling a single phase voltage controlled rectifier using Laplace transforms

NASA Technical Reports Server (NTRS)

Kraft, L. Alan; Kankam, M. David

1992-01-01

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

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

PubMed Central

Lee, Hyung-Min; Ghovanloo, Maysam

2011-01-01

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

Fast controller for a unity-power-factor PWM rectifier

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

Eissa, M.O.; Leeb, S.B.; Verghese, G.C.

1996-01-01

This paper presents an analog implementation of a fast controller for a unity-power-factor (UPF) PWM rectifier. The best settling times of many popular controllers for this type of converter are on the order of a few line cycles, corresponding to bandwidths under 20 Hz. The fast controller demonstrated in this paper can exercise control action at a rate comparable to the switching frequency rather than the line frequency. In order to accomplish this while maintaining unity power factor during steady-state operation, the fast controller employs a ripple-feedback cancellation scheme.

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

NASA Technical Reports Server (NTRS)

Hanna, M. F.

1966-01-01

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

Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems.

PubMed

Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

2015-12-16

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction.

Co-Design Method and Wafer-Level Packaging Technique of Thin-Film Flexible Antenna and Silicon CMOS Rectifier Chips for Wireless-Powered Neural Interface Systems

PubMed Central

Okabe, Kenji; Jeewan, Horagodage Prabhath; Yamagiwa, Shota; Kawano, Takeshi; Ishida, Makoto; Akita, Ippei

2015-01-01

In this paper, a co-design method and a wafer-level packaging technique of a flexible antenna and a CMOS rectifier chip for use in a small-sized implantable system on the brain surface are proposed. The proposed co-design method optimizes the system architecture, and can help avoid the use of external matching components, resulting in the realization of a small-size system. In addition, the technique employed to assemble a silicon large-scale integration (LSI) chip on the very thin parylene film (5 μm) enables the integration of the rectifier circuits and the flexible antenna (rectenna). In the demonstration of wireless power transmission (WPT), the fabricated flexible rectenna achieved a maximum efficiency of 0.497% with a distance of 3 cm between antennas. In addition, WPT with radio waves allows a misalignment of 185% against antenna size, implying that the misalignment has a less effect on the WPT characteristics compared with electromagnetic induction. PMID:26694407

Gate-Controlled BP-WSe2 Heterojunction Diode for Logic Rectifiers and Logic Optoelectronics.

PubMed

Li, Dong; Wang, Biao; Chen, Mingyuan; Zhou, Jun; Zhang, Zengxing

2017-06-01

p-n junctions play an important role in modern semiconductor electronics and optoelectronics, and field-effect transistors are often used for logic circuits. Here, gate-controlled logic rectifiers and logic optoelectronic devices based on stacked black phosphorus (BP) and tungsten diselenide (WSe 2 ) heterojunctions are reported. The gate-tunable ambipolar charge carriers in BP and WSe 2 enable a flexible, dynamic, and wide modulation on the heterojunctions as isotype (p-p and n-n) and anisotype (p-n) diodes, which exhibit disparate rectifying and photovoltaic properties. Based on such characteristics, it is demonstrated that BP-WSe 2 heterojunction diodes can be developed for high-performance logic rectifiers and logic optoelectronic devices. Logic optoelectronic devices can convert a light signal to an electric one by applied gate voltages. This work should be helpful to expand the applications of 2D crystals. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Real-time multi-DSP control of three-phase current-source unity power factor PWM rectifier

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

Xiao Wang; Boon-Teck Ooi

1993-07-01

The design of a real-time multi-DSP controller for a high-quality six-valve three-phase current-source unity power factor PWM rectifier is discussed in this paper. With the decoupler preprocessor and the dynamic trilogic PWM trigger scheme, each of the three input currents can be controlled independently. Based on the a-b-c frame system model and the fast parallel computer control, the pole-placement control method is implemented successfully to achieve fast response in the ac currents. The low-frequency resonance in the ac filter L-C networks has been damped effectively. The experimental results are obtained from a 1-kVA bipolar transistor current-source PWM rectifier with amore » real-time controller using three TMS320C25 DSP's.« less

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

DOEpatents

Carlson, David E.

1980-01-01

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

Rectifier cabinet static breaker

DOEpatents

Costantino, Jr, Roger A.; Gliebe, Ronald J.

1992-09-01

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

CMOS single-stage input-powered bridge rectifier with boost switch and duty cycle control

NASA Astrophysics Data System (ADS)

Radzuan, Roskhatijah; Mohd Salleh, Mohd Khairul; Hamzah, Mustafar Kamal; Ab Wahab, Norfishah

2017-06-01

This paper presents a single-stage input-powered bridge rectifier with boost switch for wireless-powered devices such as biomedical implants and wireless sensor nodes. Realised using CMOS process technology, it employs a duty cycle switch control to achieve high output voltage using boost technique, leading to a high output power conversion. It has only six external connections with the boost inductance. The input frequency of the bridge rectifier is set at 50 Hz, while the switching frequency is 100 kHz. The proposed circuit is fabricated on a single 0.18-micron CMOS die with a space area of 0.024 mm2. The simulated and measured results show good agreement.

Effects of Asymmetric Local Joule Heating on Silicon Nanowire-Based Devices Formed by Dielectrophoresis Alignment Across Pt Electrodes

NASA Astrophysics Data System (ADS)

Ho, Hsiang-Hsi; Lin, Chun-Lung; Tsai, Wei-Che; Hong, Liang-Zheng; Lyu, Cheng-Han; Hsu, Hsun-Feng

2018-01-01

We demonstrate the fabrication and characterization of silicon nanowire-based devices in metal-nanowire-metal configuration using direct current dielectrophoresis. The current-voltage characteristics of the devices were found rectifying, and their direction of rectification could be determined by voltage sweep direction due to the asymmetric Joule heating effect that occurred in the electrical measurement process. The photosensing properties of the rectifying devices were investigated. It reveals that when the rectifying device was in reverse-biased mode, the excellent photoresponse was achieved due to the strong built-in electric field at the junction interface. It is expected that rectifying silicon nanowire-based devices through this novel and facile method can be potentially applied to other applications such as logic gates and sensors.

CNFET-based voltage rectifier circuit for biomedical implantable applications

NASA Astrophysics Data System (ADS)

Tu, Yonggen; Qian, Libo; Xia, Yinshui

2017-02-01

Carbon nanotube field effect transistor (CNFET) shows lower threshold voltage and smaller leakage current in comparison to its CMOS counterpart. In this paper, two kinds of CNFET-based rectifiers, full-wave rectifiers and voltage doubler rectifiers are presented for biomedical implantable applications. Based on the standard 32 nm CNFET model, the electrical performance of CNFET rectifiers is analyzed and compared. Simulation results show the voltage conversion efficiency (VCE) and power conversion efficiency (PCE) achieve 70.82% and 72.49% for CNFET full-wave rectifiers and 56.60% and 61.17% for CNFET voltage double rectifiers at typical 1.0 V input voltage excitation, which are higher than that of CMOS design. Moreover, considering the controllable property of CNFET threshold voltage, the effect of various design parameters on the electrical performance is investigated. It is observed that the VCE and PCE of CNFET rectifier increase with increasing CNT diameter and number of tubes. The proposed results would provide some guidelines for design and optimization of CNFET-based rectifier circuits. Project supported by the National Natural Science Foundation of China (Nos. 61131001, 61404077, 61571248), the Science and Technology Fund of Zhejiang Province (No. 2015C31090), the Natural Science Foundation of Ningbo (No. 2014A610147), State Key Laboratory of ASIC & System (No. 2015KF006) and the K. C. Wong Magna Fund in Ningbo University.

Pharmacological Conversion of a Cardiac Inward Rectifier into an Outward Rectifier Potassium Channel.

PubMed

Moreno-Galindo, Eloy G; Sanchez-Chapula, Jose A; Tristani-Firouzi, Martin; Navarro-Polanco, Ricardo A

2016-09-01

Potassium (K(+)) channels are crucial for determining the shape, duration, and frequency of action-potential firing in excitable cells. Broadly speaking, K(+) channels can be classified based on whether their macroscopic current outwardly or inwardly rectifies, whereby rectification refers to a change in conductance with voltage. Outwardly rectifying K(+) channels conduct greater current at depolarized membrane potentials, whereas inward rectifier channels conduct greater current at hyperpolarized membrane potentials. Under most circumstances, outward currents through inwardly rectifying K(+) channels are reduced at more depolarized potentials. However, the acetylcholine-gated K(+) channel (KACh) conducts current that inwardly rectifies when activated by some ligands (such as acetylcholine), and yet conducts current that outwardly rectifies when activated by other ligands (for example, pilocarpine and choline). The perplexing and paradoxical behavior of KACh channels is due to the intrinsic voltage sensitivity of the receptor that activates KACh channels, the M2 muscarinic receptor (M2R). Emerging evidence reveals that the affinity of M2R for distinct ligands varies in a voltage-dependent and ligand-specific manner. These intrinsic receptor properties determine whether current conducted by KACh channels inwardly or outwardly rectifies. This review summarizes the most recent concepts regarding the intrinsic voltage sensitivity of muscarinic receptors and the consequences of this intriguing behavior on cardiac physiology and pharmacology of KACh channels. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon

NASA Astrophysics Data System (ADS)

Pradeepkumar, Aiswarya; Zielinski, Marcin; Bosi, Matteo; Verzellesi, Giovanni; Gaskill, D. Kurt; Iacopi, Francesca

2018-06-01

Heteroepitaxial 3C-SiC films on silicon substrates are of technological interest as enablers to integrate the excellent electrical, electronic, mechanical, thermal, and epitaxial properties of bulk silicon carbide into well-established silicon technologies. One critical bottleneck of this integration is the establishment of a stable and reliable electronic junction at the heteroepitaxial interface of the n-type SiC with the silicon substrate. We have thus investigated in detail the electrical and transport properties of heteroepitaxial cubic silicon carbide films grown via different methods on low-doped and high-resistivity silicon substrates by using van der Pauw Hall and transfer length measurements as test vehicles. We have found that Si and C intermixing upon or after growth, particularly by the diffusion of carbon into the silicon matrix, creates extensive interstitial carbon traps and hampers the formation of a stable rectifying or insulating junction at the SiC/Si interface. Although a reliable p-n junction may not be realistic in the SiC/Si system, we can achieve, from a point of view of the electrical isolation of in-plane SiC structures, leakage suppression through the substrate by using a high-resistivity silicon substrate coupled with deep recess etching in between the SiC structures.

Inward rectifier potassium channels control rotor frequency in ventricular fibrillation.

PubMed

Jalife, José

2009-11-01

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, I(K1,) is an important current during functional reentry because it mediates the electrotonic interactions between the unexcited core and its immediate surroundings. In addition, I(K1) is a stabilizer of reentry due to its ability to shorten action potential duration and reduce conduction velocity near the center of rotation. Increased I(K1) prevents wave front-wave tail interactions and thus averts rotor destabilization and breakup. Other studies have shown that while the slow component of the delayed rectifier potassium current I(Ks) does not significantly modify rotor frequency or stability, it plays a major role in postrepolarization refractoriness and wave break formation. Therefore, the interplay between I(K1) and the rapid sodium inward current (I(Na)) is a major factor in the control of cardiac excitability and thus the stability and frequency of reentry, while I(Ks) is an important determinant of fibrillatory conduction.

Inward Rectifier Potassium Channels Control Rotor Frequency in Ventricular Fibrillation

PubMed Central

Jalife, José

2009-01-01

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. PMID:19880073

Electron transport through rectifying self-assembled monolayer diodes on silicon: Fermi-level pinning at the molecule-metal interface.

PubMed

Lenfant, S; Guerin, D; Tran Van, F; Chevrot, C; Palacin, S; Bourgoin, J P; Bouloussa, O; Rondelez, F; Vuillaume, D

2006-07-20

We report the synthesis and characterization of molecular rectifying diodes on silicon using sequential grafting of self-assembled monolayers of alkyl chains bearing a pi group at their outer end (Si/sigma-pi/metal junctions). We investigate the structure-performance relationships of these molecular devices, and we examine the extent to which the nature of the pi end group (change in the energy position of their molecular orbitals) drives the properties of these molecular diodes. Self-assembled monolayers of alkyl chains (different chain lengths from 6 to 15 methylene groups) functionalized by phenyl, anthracene, pyrene, ethylene dioxythiophene, ethylene dioxyphenyl, thiophene, terthiophene, and quaterthiophene were synthesized and characterized by contact angle measurements, ellipsometry, Fourier transform infrared spectroscopy, and atomic force microscopy. We demonstrate that reasonably well-packed monolayers are obtained in all cases. Their electrical properties were assessed by dc current-voltage characteristics and high-frequency (1-MHz) capacitance measurements. For all of the pi groups investigated here, we observed rectification behavior. These results extend our preliminary work using phenyl and thiophene groups (Lenfant et al., Nano Lett. 2003, 3, 741). The experimental current-voltage curves were analyzed with a simple analytical model, from which we extracted the energy position of the molecular orbital of the pi group in resonance with the Fermi energy of the electrodes. We report experimental studies of the band lineup in these silicon/alkyl pi-conjugated molecule/metal junctions. We conclude that Fermi-level pinning at the pi group/metal interface is mainly responsible for the observed absence of a dependence of the rectification effect on the nature of the pi groups, even though the groups examined were selected to have significant variations in their electronic molecular orbitals.

Feedback loop compensates for rectifier nonlinearity

NASA Technical Reports Server (NTRS)

1966-01-01

Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

Combinational logic for generating gate drive signals for phase control rectifiers

NASA Technical Reports Server (NTRS)

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

1982-01-01

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

Precision rectifier detectors for ac resistance bridge measurements with application to temperature control systems for irradiation creep experiments

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

Duncan, M. G.

The suitability of several temperature measurement schemes for an irradiation creep experiment is examined. It is found that the specimen resistance can be used to measure and control the sample temperature if compensated for resistance drift due to radiation and annealing effects. A modified Kelvin bridge is presented that allows compensation for resistance drift by periodically checking the sample resistance at a controlled ambient temperature. A new phase-insensitive method for detecting the bridge error signals is presented. The phase-insensitive detector is formed by averaging the magnitude of two bridge voltages. Although this method is substantially less sensitive to stray reactancesmore » in the bridge than conventional phase-sensitive detectors, it is sensitive to gain stability and linearity of the rectifier circuits. Accuracy limitations of rectifier circuits are examined both theoretically and experimentally in great detail. Both hand analyses and computer simulations of rectifier errors are presented. Finally, the design of a temperature control system based on sample resistance measurement is presented. The prototype is shown to control a 316 stainless steel sample to within a 0.15/sup 0/C short term (10 sec) and a 0.03/sup 0/C long term (10 min) standard deviation at temperatures between 150 and 700/sup 0/C. The phase-insensitive detector typically contributes less than 10 ppM peak resistance measurement error (0.04/sup 0/C at 700/sup 0/C for 316 stainless steel or 0.005/sup 0/C at 150/sup 0/C for zirconium).« less

Thin-film semiconductor rectifier has improved properties

NASA Technical Reports Server (NTRS)

1966-01-01

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

Silicon Sheet Quality is Improved By Meniscus Control

NASA Technical Reports Server (NTRS)

Yates, D. A.; Hatch, A. E.; Goldsmith, J. M.

1983-01-01

Better quality silicon crystals for solar cells are possible with instrument that monitors position of meniscus as sheet of solid silicon is drawn from melt. Using information on meniscus height, instrument generates feedback signal to control melt temperature. Automatic control ensures more uniform silicon sheets.

Resonant Rectifier ICs for Piezoelectric Energy Harvesting Using Low-Voltage Drop Diode Equivalents

PubMed Central

Din, Amad Ud; Chandrathna, Seneke Chamith; Lee, Jong-Wook

2017-01-01

Herein, we present the design technique of a resonant rectifier for piezoelectric (PE) energy harvesting. We propose two diode equivalents to reduce the voltage drop in the rectifier operation, a minuscule-drop-diode equivalent (MDDE) and a low-drop-diode equivalent (LDDE). The diode equivalents are embedded in resonant rectifier integrated circuits (ICs), which use symmetric bias-flip to reduce the power used for charging and discharging the internal capacitance of a PE transducer. The self-startup function is supported by synchronously generating control pulses for the bias-flip from the PE transducer. Two resonant rectifier ICs, using both MDDE and LDDE, are fabricated in a 0.18 μm CMOS process and their performances are characterized under external and self-power conditions. Under the external-power condition, the rectifier using LDDE delivers an output power POUT of 564 μW and a rectifier output voltage VRECT of 3.36 V with a power transfer efficiency of 68.1%. Under self-power conditions, the rectifier using MDDE delivers a POUT of 288 μW and a VRECT of 2.4 V with a corresponding efficiency of 78.4%. Using the proposed bias-flip technique, the power extraction capability of the proposed rectifier is 5.9 and 3.0 times higher than that of a conventional full-bridge rectifier. PMID:28422085

Resonant Rectifier ICs for Piezoelectric Energy Harvesting Using Low-Voltage Drop Diode Equivalents.

PubMed

Din, Amad Ud; Chandrathna, Seneke Chamith; Lee, Jong-Wook

2017-04-19

Herein, we present the design technique of a resonant rectifier for piezoelectric (PE) energy harvesting. We propose two diode equivalents to reduce the voltage drop in the rectifier operation, a minuscule-drop-diode equivalent (MDDE) and a low-drop-diode equivalent (LDDE). The diode equivalents are embedded in resonant rectifier integrated circuits (ICs), which use symmetric bias-flip to reduce the power used for charging and discharging the internal capacitance of a PE transducer. The self-startup function is supported by synchronously generating control pulses for the bias-flip from the PE transducer. Two resonant rectifier ICs, using both MDDE and LDDE, are fabricated in a 0.18 μm CMOS process and their performances are characterized under external and self-power conditions. Under the external-power condition, the rectifier using LDDE delivers an output power P OUT of 564 μW and a rectifier output voltage V RECT of 3.36 V with a power transfer efficiency of 68.1%. Under self-power conditions, the rectifier using MDDE delivers a P OUT of 288 μW and a V RECT of 2.4 V with a corresponding efficiency of 78.4%. Using the proposed bias-flip technique, the power extraction capability of the proposed rectifier is 5.9 and 3.0 times higher than that of a conventional full-bridge rectifier.

Synchronous Half-Wave Rectifier

NASA Technical Reports Server (NTRS)

Rippel, Wally E.

1989-01-01

Synchronous rectifying circuit behaves like diode having unusually low voltage drop during forward-voltage half cycles. Circuit particularly useful in power supplies with potentials of 5 Vdc or less, where normal forward-voltage drops in ordinary diodes unacceptably large. Fabricated as monolithic assembly or as hybrid. Synchronous half-wave rectifier includes active circuits to attain low forward voltage drop and high rectification efficiency.

46 CFR 183.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents...

46 CFR 183.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents...

ISGV Self-rectifying Turbine Design For Thermoacoustic Application

NASA Astrophysics Data System (ADS)

Sammak, Shervin; Asghary, Maryam; Ghorbanian, Kaveh

2014-11-01

Thermoacoustic engines produce the acoustic power from wasted heat and then electricity can be generated from acoustic power. Utilizing self-rectifying turbine after a thermoacoustic engine allows for deploying standard generators with high enough rotational speed that remarkably reduce abrasion, size and cost and significantly increase efficiency and controllability in comparison with linear alternators. In this paper, by evaluating all different type of self-rectifying turbine, impulse turbine with self-piched controlled (ISGV) is chosen as the most appropriate type for this application. This kind of turbine is designed in detail for a popular engine, thermoacoustic stirling heat engine (TASHE). In order to validate the design, a full scale size of designed turbine is modeled in ANSYS CFX. As a result, optimum power and efficiency gained based on numerical data.

Functional conversion between A-type and delayed rectifier K+ channels by membrane lipids.

PubMed

Oliver, Dominik; Lien, Cheng-Chang; Soom, Malle; Baukrowitz, Thomas; Jonas, Peter; Fakler, Bernd

2004-04-09

Voltage-gated potassium (Kv) channels control action potential repolarization, interspike membrane potential, and action potential frequency in excitable cells. It is thought that the combinatorial association between distinct alpha and beta subunits determines whether Kv channels function as non-inactivating delayed rectifiers or as rapidly inactivating A-type channels. We show that membrane lipids can convert A-type channels into delayed rectifiers and vice versa. Phosphoinositides remove N-type inactivation from A-type channels by immobilizing the inactivation domains. Conversely, arachidonic acid and its amide anandamide endow delayed rectifiers with rapid voltage-dependent inactivation. The bidirectional control of Kv channel gating by lipids may provide a mechanism for the dynamic regulation of electrical signaling in the nervous system.

46 CFR 129.360 - Semiconductor-rectifier systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a...

46 CFR 120.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Semiconductor rectifier systems. 120.360 Section 120.360... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a...

46 CFR 129.360 - Semiconductor-rectifier systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a...

46 CFR 120.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 120.360 Section 120.360... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a...

High rectifying behavior in Al/Si nanocrystal-embedded SiOxNy/p-Si heterojunctions

NASA Astrophysics Data System (ADS)

Jacques, E.; Pichon, L.; Debieu, O.; Gourbilleau, F.; Coulon, N.

2011-05-01

We examine the electrical properties of MIS devices made of Al/Si nanocrystal-SiOxNy/p-Si. The J-V characteristics of the devices present a high rectifying behavior. Temperature measurements show that the forward current is thermally activated following the thermal diffusion model of carriers. At low reverse bias, the current is governed by thermal emission amplified by the Poole-Frenkel effect of carriers from defects located at the silicon nanocrystals/SiOxNy interfaces, whereas tunnel conduction in silicon oxynitride matrix dominates at high reverse bias. The devices exhibit a rectification ratio >104 for the current measured at V = ± 1 V. Study reveals that thermal annealing in forming gas (H2/N2) improves the electrical properties of the devices due to the passivation of defects.

Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids

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

Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria

2016-08-15

Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP 2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL -) with a distinct second site is required for high PIP 2sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP 2sensitivity, even in the absence of PL -. Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP 2(2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domainmore » (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL -binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP 2site and explaining the positive allostery between PL -binding and PIP 2sensitivity.« less

Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids.

PubMed

Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G

2016-09-01

Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(-)) with a distinct second site is required for high PIP2 sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2 sensitivity, even in the absence of PL(-) Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP2 (2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL(-) binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP2 site and explaining the positive allostery between PL(-) binding and PIP2 sensitivity. © 2016 Lee et al.

Confined in-fiber solidification and structural control of silicon and silicon-germanium microparticles.

PubMed

Gumennik, Alexander; Levy, Etgar C; Grena, Benjamin; Hou, Chong; Rein, Michael; Abouraddy, Ayman F; Joannopoulos, John D; Fink, Yoel

2017-07-11

Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon-germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon-germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices.

Silicon Carbide Technology

NASA Technical Reports Server (NTRS)

Neudeck, Philip G.

2006-01-01

Silicon carbide based semiconductor electronic devices and circuits are presently being developed for use in high-temperature, high-power, and high-radiation conditions under which conventional semiconductors cannot adequately perform. Silicon carbide's ability to function under such extreme conditions is expected to enable significant improvements to a far-ranging variety of applications and systems. These range from greatly improved high-voltage switching for energy savings in public electric power distribution and electric motor drives to more powerful microwave electronics for radar and communications to sensors and controls for cleaner-burning more fuel-efficient jet aircraft and automobile engines. In the particular area of power devices, theoretical appraisals have indicated that SiC power MOSFET's and diode rectifiers would operate over higher voltage and temperature ranges, have superior switching characteristics, and yet have die sizes nearly 20 times smaller than correspondingly rated silicon-based devices [8]. However, these tremendous theoretical advantages have yet to be widely realized in commercially available SiC devices, primarily owing to the fact that SiC's relatively immature crystal growth and device fabrication technologies are not yet sufficiently developed to the degree required for reliable incorporation into most electronic systems. This chapter briefly surveys the SiC semiconductor electronics technology. In particular, the differences (both good and bad) between SiC electronics technology and the well-known silicon VLSI technology are highlighted. Projected performance benefits of SiC electronics are highlighted for several large-scale applications. Key crystal growth and device-fabrication issues that presently limit the performance and capability of high-temperature and high-power SiC electronics are identified.

Spatial fluctuations in barrier height at the graphene-silicon carbide Schottky junction.

PubMed

Rajput, S; Chen, M X; Liu, Y; Li, Y Y; Weinert, M; Li, L

2013-01-01

When graphene is interfaced with a semiconductor, a Schottky contact forms with rectifying properties. Graphene, however, is also susceptible to the formation of ripples upon making contact with another material. Here we report intrinsic ripple- and electric field-induced effects at the graphene semiconductor Schottky junction, by comparing chemical vapour-deposited graphene transferred on semiconductor surfaces of opposite polarization-the hydrogen-terminated silicon and carbon faces of hexagonal silicon carbide. Using scanning tunnelling microscopy/spectroscopy and first-principles calculations, we show the formation of a narrow Schottky dipole barrier approximately 10 Å wide, which facilitates the observed effective electric field control of the Schottky barrier height. We further find atomic-scale spatial fluctuations in the Schottky barrier that directly follow the undulation of ripples on both graphene-silicon carbide junctions. These findings reveal fundamental properties of the graphene/semiconductor Schottky junction-a key component of vertical graphene devices that offer functionalities unattainable in planar device architecture.

Junction barrier Schottky rectifier with an improved P-well region

NASA Astrophysics Data System (ADS)

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

2012-12-01

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

The Development of High-Density Vertical Silicon Nanowires and Their Application in a Heterojunction Diode.

PubMed

Chang, Wen-Chung; Su, Sheng-Chien; Wu, Chia-Ching

2016-06-30

Vertically aligned p-type silicon nanowire (SiNW) arrays were fabricated through metal-assisted chemical etching (MACE) of Si wafers. An indium tin oxide/indium zinc oxide/silicon nanowire (ITO/IZO/SiNW) heterojunction diode was formed by depositing ITO and IZO thin films on the vertically aligned SiNW arrays. The structural and electrical properties of the resulting ITO/IZO/SiNW heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and current-voltage (I-V) measurements. Nonlinear and rectifying I-V properties confirmed that a heterojunction diode was successfully formed in the ITO/IZO/SiNW structure. The diode had a well-defined rectifying behavior, with a rectification ratio of 550.7 at 3 V and a turn-on voltage of 2.53 V under dark conditions.

The Development of High-Density Vertical Silicon Nanowires and Their Application in a Heterojunction Diode

PubMed Central

Chang, Wen-Chung; Su, Sheng-Chien; Wu, Chia-Ching

2016-01-01

Vertically aligned p-type silicon nanowire (SiNW) arrays were fabricated through metal-assisted chemical etching (MACE) of Si wafers. An indium tin oxide/indium zinc oxide/silicon nanowire (ITO/IZO/SiNW) heterojunction diode was formed by depositing ITO and IZO thin films on the vertically aligned SiNW arrays. The structural and electrical properties of the resulting ITO/IZO/SiNW heterojunction diode were characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and current−voltage (I−V) measurements. Nonlinear and rectifying I−V properties confirmed that a heterojunction diode was successfully formed in the ITO/IZO/SiNW structure. The diode had a well-defined rectifying behavior, with a rectification ratio of 550.7 at 3 V and a turn-on voltage of 2.53 V under dark conditions. PMID:28773656

46 CFR 129.360 - Semiconductor-rectifier systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS ELECTRICAL INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each...

46 CFR 129.360 - Semiconductor-rectifier systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS ELECTRICAL INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each...

46 CFR 183.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 7 2014-10-01 2014-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...

46 CFR 183.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 7 2012-10-01 2012-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...

46 CFR 129.360 - Semiconductor-rectifier systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OFFSHORE SUPPLY VESSELS ELECTRICAL INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each...

46 CFR 183.360 - Semiconductor rectifier systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 7 2013-10-01 2013-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL PASSENGER VESSELS (UNDER 100 GROSS TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier...

Curvature Control of Silicon Microlens for THz Dielectric Antenna

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

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

PubMed

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

2015-03-01

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

Controlling temperature dependence of silicon waveguide using slot structure.

PubMed

Lee, Jong-Moo; Kim, Duk-Jun; Kim, Gwan-Ha; Kwon, O-Kyun; Kim, Kap-Joong; Kim, Gyungock

2008-02-04

We show that the temperature dependence of a silicon waveguide can be controlled well by using a slot waveguide structure filled with a polymer material. Without a slot, the amount of temperature-dependent wavelength shift for TE mode of a silicon waveguide ring resonator is very slightly reduced from 77 pm/ degrees C to 66 pm/ degrees C by using a polymer (WIR30-490) upper cladding instead of air upper cladding. With a slot filled with the same polymer, however, the reduction of the temperature dependence is improved by a pronounced amount and can be controlled down to -2 pm/ degrees C by adjusting several variables of the slot structure, such as the width of the slot between the pair of silicon wires, the width of the silicon wire pair, and the height of the silicon slab in our experiment. This measurement proves that a reduction in temperature dependence can be improved about 8 times more by using the slot structure.

A silicon central pattern generator controls locomotion in vivo.

PubMed

Vogelstein, R J; Tenore, F; Guevremont, L; Etienne-Cummings, R; Mushahwar, V K

2008-09-01

We present a neuromorphic silicon chip that emulates the activity of the biological spinal central pattern generator (CPG) and creates locomotor patterns to support walking. The chip implements ten integrate-and-fire silicon neurons and 190 programmable digital-to-analog converters that act as synapses. This architecture allows for each neuron to make synaptic connections to any of the other neurons as well as to any of eight external input signals and one tonic bias input. The chip's functionality is confirmed by a series of experiments in which it controls the motor output of a paralyzed animal in real-time and enables it to walk along a three-meter platform. The walking is controlled under closed-loop conditions with the aide of sensory feedback that is recorded from the animal's legs and fed into the silicon CPG. Although we and others have previously described biomimetic silicon locomotor control systems for robots, this is the first demonstration of a neuromorphic device that can replace some functions of the central nervous system in vivo.

Inhibition of cardiac inward rectifier currents by cationic amphiphilic drugs.

PubMed

van der Heyden, M A G; Stary-Weinzinger, A; Sanchez-Chapula, J A

2013-09-01

Cardiac inward rectifier channels belong to three different classes of the KIR channel protein family. The KIR2.x proteins generate the classical inward rectifier current, IK1, while KIR3 and KIR6 members are responsible for the acetylcholine responsive and ATP sensitive inward rectifier currents IKAch and IKATP, respectively. Aberrant function of these channels has been correlated with severe cardiac arrhythmias, indicating their significant contribution to normal cardiac electrophysiology. A common feature of inward rectifier channels is their dependence on the lipid phosphatidyl-4,5-bisphospate (PIP2) interaction for functional activity. Cationic amphiphilic drugs (CADs) are one of the largest classes of pharmaceutical compounds. Several widely used CADs have been associated with inward rectifier current disturbances, and recent evidence points to interference of the channel-PIP2 interaction as the underlying mechanism of action. Here, we will review how six of these well known drugs, used for treatment in various different conditions, interfere in cardiac inward rectifier functioning. In contrast, KIR channel inhibition by the anionic anesthetic thiopental is achieved by a different mechanism of channel-PIP2 interference. We will discuss the latest basic science insights of functional inward rectifier current characteristics, recently derived KIR channel structures and specific PIP2-receptor interactions at the molecular level and provide insight in how these drugs interfere in the structure-function relationships.

What controls silicon isotope fractionation during dissolution of diatom opal?

NASA Astrophysics Data System (ADS)

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

2014-04-01

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

Controlling the Nanoscale Patterning of AuNPs on Silicon Surfaces

PubMed Central

Williams, Sophie E.; Davies, Philip R.; Bowen, Jenna L.; Allender, Chris J.

2013-01-01

This study evaluates the effectiveness of vapour-phase deposition for creating sub-monolayer coverage of aminopropyl triethoxysilane (APTES) on silicon in order to exert control over subsequent gold nanoparticle deposition. Surface coverage was evaluated indirectly by observing the extent to which gold nanoparticles (AuNPs) deposited onto the modified silicon surface. By varying the distance of the silicon wafer from the APTES source and concentration of APTES in the evaporating media, control over subsequent gold nanoparticle deposition was achievable to an extent. Fine control over AuNP deposition (AuNPs/μm2) however, was best achieved by adjusting the ionic concentration of the AuNP-depositing solution. Furthermore it was demonstrated that although APTES was fully removed from the silicon surface following four hours incubation in water, the gold nanoparticle-amino surface complex was stable under the same conditions. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to study these affects. PMID:28348330

Automatic Control of Silicon Melt Level

NASA Technical Reports Server (NTRS)

Duncan, C. S.; Stickel, W. B.

1982-01-01

A new circuit, when combined with melt-replenishment system and melt level sensor, offers continuous closed-loop automatic control of melt-level during web growth. Installed on silicon-web furnace, circuit controls melt-level to within 0.1 mm for as long as 8 hours. Circuit affords greater area growth rate and higher web quality, automatic melt-level control also allows semiautomatic growth of web over long periods which can greatly reduce costs.

27 CFR 1.21 - Domestic producers, rectifiers, blenders, and warehousemen.

Code of Federal Regulations, 2011 CFR

2011-04-01

... in the business of distilling distilled spirits, producing wine, rectifying or blending distilled... or indirectly or through an affiliate, distilled spirits or wine so distilled, produced, rectified...

Nonlinear Silicon Photonics: Extending Platforms, Control, and Applications

NASA Astrophysics Data System (ADS)

Miller, Steven Andrew

Silicon photonics is a revolutionary technology that enables the control of light inside a silicon chip and holds promise to impact many applications from data center optical interconnects to optical sensing and even quantum optics. The tight confinement of light inside these chips greatly enhances light-matter interactions, making this an ideal platform for nonlinear photonics. Recently, microresonator-based Kerr frequency comb generation has become a prevalent emerging field, enabling the generation of a broadband optical pulse train by inputting a low-power continuous-wave laser into a low-loss chip-scale micro-cavity. These chip-scale combs have a wide variety of applications, including optical clocks, optical spectroscopy, and data communications. Several important applications in biological, chemical and atmospheric areas require combs generated in the visible and mid-infrared wavelength ranges, where there has been far less research and development compared with the near-infrared. Additionally, most platforms widely for combs are passive, limiting the ability to control and optimize the frequency combs. In this dissertation, we set out to address these shortcomings and introduce new tunability as well as wavelength flexibility in order to enable new applications for microresonator frequency combs. The silicon nitride platform for near-infrared combs is generally a passive platform with limited tuning capabilities. We overcome dispersion limitations in the visible range by leveraging the second-order nonlinearity of silicon nitride and demonstrate visible comb lines. We then further investigate the second-order nonlinearity of silicon nitride by measuring the linear electro-optic effect, a potential tuning mechanism. Finally, we introduce thermal tuning onto the silicon nitride platform and demonstrate tuning of the resonance extinction and dispersion of a micro-cavity using a coupled cavity design. We also address the silicon mid-infrared frequency comb

Wireless power transmission for biomedical implants: The role of near-zero threshold CMOS rectifiers.

PubMed

Mohammadi, Ali; Redoute, Jean-Michel; Yuce, Mehmet R

2015-01-01

Biomedical implants require an electronic power conditioning circuitry to provide a stable electrical power supply. The efficiency of wireless power transmission is strongly dependent on the power conditioning circuitry specifically the rectifier. A cross-connected CMOS bridge rectifier is implemented to demonstrate the impact of thresholds of rectifiers on wireless power transfer. The performance of the proposed rectifier is experimentally compared with a conventional Schottky diode full wave rectifier over 9 cm distance of air and tissue medium between the transmitter and receiver. The output voltage generated by the CMOS rectifier across a 1 KΩ resistive load is around twice as much as the Schottky rectifier.

A 13.56 MHz CMOS Active Rectifier With Switched-Offset and Compensated Biasing for Biomedical Wireless Power Transfer Systems.

PubMed

Yan Lu; Wing-Hung Ki

2014-06-01

A full-wave active rectifier switching at 13.56 MHz with compensated bias current for a wide input range for wirelessly powered high-current biomedical implants is presented. The four diodes of a conventional passive rectifier are replaced by two cross-coupled PMOS transistors and two comparator- controlled NMOS switches to eliminate diode voltage drops such that high voltage conversion ratio and power conversion efficiency could be achieved even at low AC input amplitude |VAC|. The comparators are implemented with switched-offset biasing to compensate for the delays of active diodes and to eliminate multiple pulsing and reverse current. The proposed rectifier uses a modified CMOS peaking current source with bias current that is quasi-inversely proportional to the supply voltage to better control the reverse current over a wide AC input range (1.5 to 4 V). The rectifier was fabricated in a standard 0.35 μm CMOS N-well process with active area of 0.0651 mm(2). For the proposed rectifier measured at |VAC| = 3.0 V, the voltage conversion ratios are 0.89 and 0.93 for RL=500 Ω and 5 kΩ, respectively, and the measured power conversion efficiencies are 82.2% to 90.1% with |VAC| ranges from 1.5 to 4 V for RL=500 Ω.

Control system adds to precipitator efficiency

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

Gurrole, G.

1978-02-01

An electrostatic precipitator in use at Lion Oil Co., Martinez, Calif., in a fluid catalytic cracking and CO boiler application, was upgraded by mechanical sectionalization of the gas passage and a new electronic control system. The electrostatic precipitator is installed upstream of the CO boiler to handle gas flow up to 4.77 ft/sec, and pressure to 4.5 psi. The independent gas chambers in the electrostatic precipitator were divided by installing gas-tight partition walls to form a total of four electrostatic fields. The precipitator was also equipped with adjustable inlet gas flow-control baffles for even gas distribution. Rows of grounded collectingmore » electrodes are parallel with the flow of gas. The emitting electrode system, powered by separate high-energy transformers for each collecting field, uses silicon-controlled rectifiers and analog electronic networks for rapid response to changing gas and dust conditions. Regulatory requirements call for efficient collection of catalyst fines with no more than 40 lb/hr escaping through the boiler stack. Currently, stack losses average about 38 lb/hr. The installation of two additional control systems with transformers and rectifiers should reduce stack losses to 34 lb/hr.« less

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

DOEpatents

Wang, Qi [Littleton, CO; Stradins, Paul [Golden, CO; Teplin, Charles [Boulder, CO; Branz, Howard M [Boulder, CO

2009-10-13

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

An overview of self-switching diode rectifiers using green materials

NASA Astrophysics Data System (ADS)

Kasjoo, Shahrir Rizal; Zailan, Zarimawaty; Zakaria, Nor Farhani; Isa, Muammar Mohamad; Arshad, Mohd Khairuddin Md; Taking, Sanna

2017-09-01

A unipolar two-terminal nanodevice, known as the self-switching diode (SSD), has recently been demonstrated as a room-temperature rectifier at microwave and terahertz frequencies due to its nonlinear current-voltage characteristic. The planar architecture of SSD not only makes the fabrication process of the device faster, simpler and at a lower cost when compared with other rectifying diodes, but also allows the use of various materials to realize and fabricate SSDs. This includes the utilization of `green' materials such as organic and graphene thin films for environmental sustainability. This paper reviews the properties of current `green' SSD rectifiers with respect to their operating frequencies and rectifying performances, including responsivity and noise-equivalent power of the devices, along with the applications.

A spin current rectifier

NASA Astrophysics Data System (ADS)

Eyni, Zahra; Mohammadpour, Hakimeh

2017-12-01

Current modulation and rectification is an important subject of electronics as well as spintronics. In this paper, an efficient rectifying mesoscopic device is introduced. The device is a two terminal device on the 2D plane of electron gas. The lateral contacts are half-metal ferromagnetic with antiparallel magnetizations and the central channel region is taken as ferromagnetic or normal in the presence of an applied magnetic field. The device functionality is based on the modification of spin-current by tuning the strength of the magnetic field or equivalently by the exchange coupling of the channel to the substrate. The result is that the (spin-) current depends on the polarity of the bias voltage. Converting an alternating bias voltage to direct current is the main achievement of this model device with an additional profit of rectified spin-current. We analyze the results in terms of the spin-dependent barrier in the channel. Detecting the strength of the magnetic field by spin polarization is also suggested.

Harmonic Characteristics of Rectifier Substations and Their Impact on Audio Frequency Track Circuits

DOT National Transportation Integrated Search

1982-05-01

This report describes the basic operation of substation rectifier equipment and the modes of possible interference with audio frequency track circuits used for train detection, cab signalling, and vehicle speed control. It also includes methods of es...

Cardiac Delayed Rectifier Potassium Channels in Health and Disease.

PubMed

Chen, Lei; Sampson, Kevin J; Kass, Robert S

2016-06-01

Cardiac delayed rectifier potassium channels conduct outward potassium currents during the plateau phase of action potentials and play pivotal roles in cardiac repolarization. These include IKs, IKr and the atrial specific IKur channels. In this article, we will review their molecular identities and biophysical properties. Mutations in the genes encoding delayed rectifiers lead to loss- or gain-of-function phenotypes, disrupt normal cardiac repolarization and result in various cardiac rhythm disorders, including congenital Long QT Syndrome, Short QT Syndrome and familial atrial fibrillation. We will also discuss the prospect of using delayed rectifier channels as therapeutic targets to manage cardiac arrhythmia. Copyright © 2016 Elsevier Inc. All rights reserved.

Cardiac Delayed Rectifier Potassium Channels in Health and Disease

PubMed Central

Chen, Lei; Sampson, Kevin J.; Kass, Robert S.

2016-01-01

Cardiac delayed rectifier potassium channels conduct outward potassium currents during the plateau phase of action potentials and play pivotal roles in cardiac repolarization. These include IKs, IKr and the atrial specific IKur channels. In this chapter, we will review the molecular identities and biophysical properties of these channels. Mutations in the genes encoding delayed rectifiers lead to loss- or gain-of-function phenotypes, disrupt normal cardiac repolarization and result in various cardiac rhythm disorders, including congenital Long QT Syndrome, Short QT Syndrome and familial atrial fibrillation. We will also discuss the possibility and prospect of using delayed rectifier channels as therapeutic targets to manage cardiac arrhythmia. PMID:27261823

A metamaterial electromagnetic energy rectifying surface with high harvesting efficiency

NASA Astrophysics Data System (ADS)

Duan, Xin; Chen, Xing; Zhou, Lin

2016-12-01

A novel metamaterial rectifying surface (MRS) for electromagnetic energy capture and rectification with high harvesting efficiency is presented. It is fabricated on a three-layer printed circuit board, which comprises an array of periodic metamaterial particles in the shape of mirrored split rings, a metal ground, and integrated rectifiers employing Schottky diodes. Perfect impedance matching is engineered at two interfaces, i.e. one between free space and the surface, and the other between the metamaterial particles and the rectifiers, which are connected through optimally positioned vias. Therefore, the incident electromagnetic power is captured with almost no reflection by the metamaterial particles, then channeled maximally to the rectifiers, and finally converted to direct current efficiently. Moreover, the rectifiers are behind the metal ground, avoiding the disturbance of high power incident electromagnetic waves. Such a MRS working at 2.45 GHz is designed, manufactured and measured, achieving a harvesting efficiency up to 66.9% under an incident power density of 5 mW/cm2, compared with a simulated efficiency of 72.9%. This high harvesting efficiency makes the proposed MRS an effective receiving device in practical microwave power transmission applications.

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

EPA Science Inventory

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

Ripple feedback for the resonant-filter unity-power-factor rectifier

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

Streng, S.A.; King, R.J.

1992-07-01

An unusual bucklike unity-power-factor rectifier with a resonant load-balancing network permits current-limited operation down to zero output voltage in a single-stage-topology. However, this rectifier has been found to be sensitive to ac-line voltage distortion and is potentially unstable with realistic values of ac-line impedance. In this paper, a new ripple feedback is proposed that solves both problems. A large-signal time-varying analysis is given along with incremental, quasi-static, and low-frequency approximations. Experimental verification is provided by a 500-W 50-kHz rectifier operating from the 120-V 60-Hz distribution system.

InGaAs-based planar barrier diode as microwave rectifier

NASA Astrophysics Data System (ADS)

Farhani Zakaria, Nor; Rizal Kasjoo, Shahrir; Zailan, Zarimawaty; Mohamad Isa, Muammar; Arshad, Mohd Khairuddin Md; Taking, Sanna

2018-06-01

In this report, we proposed and simulated a new planar nonlinear rectifying device fabricated using InGaAs substrate and referred to as a planar barrier diode (PBD). Using an asymmetrical inverse-arrowhead-shaped structure between the electrodes, a nonuniform depletion region is developed, which creates a triangular energy barrier in the conducting channel. This barrier is voltage dependent and can be controlled by the applied voltage across the PBD, thus resulting in nonlinear diode-like current–voltage characteristics; thus it can be used as a rectifying device. The PBD’s working principle is explained using thermionic emission theory. Furthermore, by varying the PBD’s geometric design, the asymmetry of the current–voltage characteristics can be optimized to realize superior rectification performance. By employing the optimized structural parameters, the obtained cut-off frequency of the device was approximately 270 GHz with a curvature coefficient peak of 14 V‑1 at a low DC bias voltage of 50 mV.

27 CFR 1.21 - Domestic producers, rectifiers, blenders, and warehousemen.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Domestic producers, rectifiers, blenders, and warehousemen. 1.21 Section 1.21 Alcohol, Tobacco Products and Firearms ALCOHOL AND... BOTTLING OF DISTILLED SPIRITS Basic Permits When Required § 1.21 Domestic producers, rectifiers, blenders...

Power converter for raindrop energy harvesting application: Half-wave rectifier

NASA Astrophysics Data System (ADS)

Izrin, Izhab Muhammad; Dahari, Zuraini

2017-10-01

Harvesting raindrop energy by capturing vibration from impact of raindrop have been explored extensively. Basically, raindrop energy is generated by converting the kinetic energy of raindrop into electrical energy by using polyvinylidene fluoride (PVDF) piezoelectric. In this paper, a power converter using half-wave rectifier for raindrop harvesting energy application is designed and proposed to convert damping alternating current (AC) generated by PVDF into direct current (DC). This research presents parameter analysis of raindrop simulation used in the experiment and resistive load effect on half-wave rectifier converter. The experiment is conducted by using artificial raindrop from the height of 1.3 m to simulate the effect of different resistive load on the output of half-wave rectifier converter. The results of the 0.68 MΩ resistive load showed the best performance of the half-wave rectifier converter used in raindrop harvesting energy system, which generated 3.18 Vaverage. The peak instantaneous output generated from this experiment is 15.36 µW.

Controlling Thermal Gradients During Silicon Web Growth

NASA Technical Reports Server (NTRS)

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

1983-01-01

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

Electro-magnetic transport and rectifying property of Fe{sub 2.5}Mn{sub 0.5}O{sub 4}/p-Si heterojunction

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

Aireddy, H.; Das, A. K., E-mail: amal@phy.iitkgp.ernet.in

2016-05-06

Fe{sub 2.5}Mn{sub 0.5}O{sub 4}/p-Si heterojunction was fabricated using a pulsed laser deposition technique and investigated it’s structural and electrical transport properties. The high-resolution transmission electron microscopy results reveal the formation of a polycrystalline film on silicon substrate. The heterojunction shows good rectifying property and giant negative junction magnetoresistance especially in reverse bias condition at room temperature. The origin of this giant negative junction magnetoresistance may be attributing to the injection of electrons to the majority spin-up band of the Fe{sub 2.5}Mn{sub 0.5}O{sub 4} film.

Polarization-Independent Silicon Metadevices for Efficient Optical Wavefront Control.

PubMed

Chong, Katie E; Staude, Isabelle; James, Anthony; Dominguez, Jason; Liu, Sheng; Campione, Salvatore; Subramania, Ganapathi S; Luk, Ting S; Decker, Manuel; Neshev, Dragomir N; Brener, Igal; Kivshar, Yuri S

2015-08-12

We experimentally demonstrate a functional silicon metadevice at telecom wavelengths that can efficiently control the wavefront of optical beams by imprinting a spatially varying transmittance phase independent of the polarization of the incident beam. Near-unity transmittance efficiency and close to 0-2π phase coverage are enabled by utilizing the localized electric and magnetic Mie-type resonances of low-loss silicon nanoparticles tailored to behave as electromagnetically dual-symmetric scatterers. We apply this concept to realize a metadevice that converts a Gaussian beam into a vortex beam. The required spatial distribution of transmittance phases is achieved by a variation of the lattice spacing as a single geometric control parameter.

3-D printed 2.4 GHz rectifying antenna for wireless power transfer applications

NASA Astrophysics Data System (ADS)

Skinner, Matthew

In this work, a 3D printed rectifying antenna that operates at the 2.4GHz WiFi band was designed and manufactured. The printed material did not have the same properties of bulk material, so the printed materials needed to be characterized. The antenna and rectifying circuit was printed out of Acrylonitrile Butadiene Styrene (ABS) filament and a conductive silver paste, with electrical components integrated into the circuit. Before printing the full rectifying antenna, each component was printed and evaluated. The printed antenna operated at the desired frequency with a return loss of -16 dBm with a bandwidth of 70MHz. The radiation pattern was measured in an anechoic chamber with good matching to the model. The rectifying circuit was designed in Ansys Circuit Simulation using Schottky diodes to enable the circuit to operate at lower input power levels. Two rectifying circuits were manufactured, one by printing the conductive traces with silver ink, and one with traces made from copper. The printed silver ink is less conductive than the bulk copper and therefore the output voltage of the printed rectifier was lower than the copper circuit. The copper circuit had an efficiency of 60% at 0dBm and the printed silver circuit had an efficiency of 28.6% at 0dBm. The antenna and rectifying circuits were then connected to each other and the performance was compared to a fully printed integrated rectifying antenna. The rectifying antennas were placed in front of a horn antenna while changing the power levels at the antenna. The efficiency of the whole system was lower than the individual components but an efficiency of 11% at 10dBm was measured.

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

PubMed

Atherton, D L; Davies, R

1979-10-01

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.

Polycrystalline silicon thin-film transistors with location-controlled crystal grains fabricated by excimer laser crystallization

NASA Astrophysics Data System (ADS)

Tsai, Chun-Chien; Lee, Yao-Jen; Chiang, Ko-Yu; Wang, Jyh-Liang; Lee, I.-Che; Chen, Hsu-Hsin; Wei, Kai-Fang; Chang, Ting-Kuo; Chen, Bo-Ting; Cheng, Huang-Chung

2007-11-01

In this paper, location-controlled silicon crystal grains are fabricated by the excimer laser crystallization method which employs amorphous silicon spacer structure and prepatterned thin films. The amorphous silicon spacer in nanometer-sized width formed using spacer technology is served as seed crystal to artificially control superlateral growth phenomenon during excimer laser irradiation. An array of 1.8-μm-sized disklike silicon grains is formed, and the n-channel thin-film transistors whose channels located inside the artificially-controlled crystal grains exhibit higher performance of field-effect-mobility reaching 308cm2/Vs as compared with the conventional ones. This position-manipulated silicon grains are essential to high-performance and good uniformity devices.

Tunable all-optical plasmonic rectifier in nanoscale metal-insulator-metal waveguides.

PubMed

Xu, Yi; Wang, Xiaomeng; Deng, Haidong; Guo, Kangxian

2014-10-15

We propose a tunable all-optical plasmonic rectifier based on the nonlinear Fano resonance in a metal-insulator-metal plasmonic waveguide and cavities coupling system. We develop a theoretical model based on the temporal coupled-mode theory to study the device physics of the nanoscale rectifier. We further demonstrate via the finite difference time domain numerical experiment that our idea can be realized in a plasmonic system with an ultracompact size of ~120×800  nm². The tunable plasmonic rectifier could facilitate the all-optical signal processing in nanoscale.

Polarization-independent silicon metadevices for efficient optical wavefront control

DOE PAGES

Chong, Katie E.; Staude, Isabelle; James, Anthony Randolph; ...

2015-07-20

In this study, we experimentally demonstrate a functional silicon metadevice at telecom wavelengths that can efficiently control the wavefront of optical beams by imprinting a spatially varying transmittance phase independent of the polarization of the incident beam. Near-unity transmittance efficiency and close to 0–2π phase coverage are enabled by utilizing the localized electric and magnetic Mie-type resonances of low-loss silicon nanoparticles tailored to behave as electromagnetically dual-symmetric scatterers. We apply this concept to realize a metadevice that converts a Gaussian beam into a vortex beam. The required spatial distribution of transmittance phases is achieved by a variation of the latticemore » spacing as a single geometric control parameter.« less

Polarization-independent silicon metadevices for efficient optical wavefront control

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

Chong, Katie E.; Staude, Isabelle; James, Anthony Randolph

In this study, we experimentally demonstrate a functional silicon metadevice at telecom wavelengths that can efficiently control the wavefront of optical beams by imprinting a spatially varying transmittance phase independent of the polarization of the incident beam. Near-unity transmittance efficiency and close to 0–2π phase coverage are enabled by utilizing the localized electric and magnetic Mie-type resonances of low-loss silicon nanoparticles tailored to behave as electromagnetically dual-symmetric scatterers. We apply this concept to realize a metadevice that converts a Gaussian beam into a vortex beam. The required spatial distribution of transmittance phases is achieved by a variation of the latticemore » spacing as a single geometric control parameter.« less

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

PubMed

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

2011-01-01

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-μm 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.

Power combining in an array of microwave power rectifiers

NASA Technical Reports Server (NTRS)

Gutmann, R. J.; Borrego, J. M.

1979-01-01

This work analyzes the resultant efficiency degradation when identical rectifiers operate at different RF power levels as caused by the power beam taper. Both a closed-form analytical circuit model and a detailed computer-simulation model are used to obtain the output dc load line of the rectifier. The efficiency degradation is nearly identical with series and parallel combining, and the closed-form analytical model provides results which are similar to the detailed computer-simulation model.

Treatment to Control Adhesion of Silicone-Based Elastomers

NASA Technical Reports Server (NTRS)

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

2013-01-01

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

Control of resting membrane potential by delayed rectifier potassium currents in ferret airway smooth muscle cells.

PubMed Central

Fleischmann, B K; Washabau, R J; Kotlikoff, M I

1993-01-01

1. In order to determine the physiological role of specific potassium currents in airway smooth muscle, potassium currents were measured in freshly dissociated ferret trachealis cells using the nystatin-permeabilized, whole-cell method, at 35 degrees C. 2. The magnitude of the outward currents was markedly increased as bath temperature was increased from 22 to 35 degrees C. This increase was primarily due to the increase in maximum potassium conductance (gK,max), although there was also a small leftward shift in the relationship between gK and voltage at higher temperatures. The maximum conductance and the kinetics of current activation and inactivation were also temperature dependent. At 35 degrees C, gating of the current was steeply voltage dependent between -40 and 0 mV. Current activation was well fitted by fourth-order kinetics; the mean time constants of activation (30 mV clamp step) were 1.09 +/- 0.17 and 1.96 +/- 0.27 ms at 35 and 22 degrees C, respectively. 3. Outward currents using the nystatin method were qualitatively similar to delayed rectifier currents recorded in dialysed cells with high calcium buffering capacity solutions. 4-Aminopyridine (4-AP; 2 mM), a specific blocker of delayed rectifier potassium channels in this tissue, inhibited over 80% of the outward current evoked by voltage-clamp steps to between -10 and +20 mV (n = 6). Less than 5% of the outward current was blocked over the same voltage range by charybdotoxin (100 nM; n = 15), a specific antagonist of large-conductance, calcium-activated potassium channels in this tissue. 4. The degree to which delayed rectifier and calcium-activated potassium conductances control resting membrane potential was examined in current-clamp experiments. The resting membrane potential of current clamped cells was -33.6 +/- 1.0 mV (n = 62). Application of 4-AP (2 mM) resulted in a 14.4 +/- 1.0 mV depolarization (n = 8) and an increase in input resistance. Charybdotoxin (100 nM) had no effect on resting

CMOS-Compatible Room-Temperature Rectifier Toward Terahertz Radiation Detection

NASA Astrophysics Data System (ADS)

Varlamava, Volha; De Amicis, Giovanni; Del Monte, Andrea; Perticaroli, Stefano; Rao, Rosario; Palma, Fabrizio

2016-08-01

In this paper, we present a new rectifying device, compatible with the technology of CMOS image sensors, suitable for implementing a direct-conversion detector operating at room temperature for operation at up to terahertz frequencies. The rectifying device can be obtained by introducing some simple modifications of the charge-storage well in conventional CMOS integrated circuits, making the proposed solution easy to integrate with the existing imaging systems. The rectifying device is combined with the different elements of the detector, composed of a 3D high-performance antenna and a charge-storage well. In particular, its position just below the edge of the 3D antenna takes maximum advantage of the high electric field concentrated by the antenna itself. In addition, the proposed structure ensures the integrity of the charge-storage well of the detector. In the structure, it is not necessary to use very scaled and costly technological nodes, since the CMOS transistor only provides the necessary integrated readout electronics. On-wafer measurements of RF characteristics of the designed junction are reported and discussed. The overall performances of the entire detector in terms of noise equivalent power (NEP) are evaluated by combining low-frequency measurements of the rectifier with numerical simulations of the 3D antenna and the semiconductor structure at 1 THz, allowing prediction of the achievable NEP.

Comparison of Rectified and Unrectified Sockets for Transtibial Amputees.

PubMed

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

2008-01-01

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.

Comparison of Rectified and Unrectified Sockets for Transtibial Amputees

PubMed Central

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

2008-01-01

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. PMID:18776945

Changes in Inward Rectifier K+ Channels in Hepatic Stellate Cells During Primary Culture

PubMed Central

Lee, Dong Hyeon; Kong, In Deok; Lee, Joong-Woo

2008-01-01

Purpose This study examined the expression and function of inward rectifier K+ channels in cultured rat hepatic stellate cells (HSC). Materials and Methods The expression of inward rectifier K+ channels was measured using real-time RT-PCR, and electrophysiological properties were determined using the gramicidin-perforated patch-clamp technique. Results The dominant inward rectifier K+ channel subtypes were Kir2.1 and Kir6.1. These dominant K+ channel subtypes decreased significantly during the primary culture throughout activation process. HSC can be classified into two subgroups: one with an inward-rectifying K+ current (type 1) and the other without (type 2). The inward current was blocked by Ba2+ (100 µM) and enhanced by high K+ (140 mM), more prominently in type 1 HSC. There was a correlation between the amplitude of the Ba2+-sensitive current and the membrane potential. In addition, Ba2+ (300 µM) depolarized the membrane potential. After the culture period, the amplitude of the inward current decreased and the membrane potential became depolarized. Conclusion HSC express inward rectifier K+ channels, which physiologically regulate membrane potential and decrease during the activation process. These results will potentially help determine properties of the inward rectifier K+ channels in HSC as well as their roles in the activation process. PMID:18581597

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

PubMed Central

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

2011-01-01

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-μm 2P3M CMOS embedded EEPROM process. The new diode achieves 315 mV turn-on voltage and 415 nA reverse saturation leakage current. Compared with the traditional rectifier, the one based on the proposed diode-connected MOS has higher PCE, higher output voltage and smaller ripple coefficient. When the RF input is a 900-MHz sinusoid signal with the power ranging from −15 dBm to −4 dBm, PCEs of the charge pump rectifier with only 3-stage are more than 30%, and the maximum output voltage is 5.5 V, and its ripple coefficients are less than 1%. Therefore, the rectifier is especially suitableto passive UHF RFID tag IC and implantable devices. PMID:22163968

Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

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

Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.

2015-12-14

Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintainingmore » high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.« less

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

PubMed

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

2014-04-01

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

Voltage mode electronically tunable full-wave rectifier

NASA Astrophysics Data System (ADS)

Petrović, Predrag B.; Vesković, Milan; Đukić, Slobodan

2017-01-01

The paper presents a new realization of bipolar full-wave rectifier of input sinusoidal signals, employing one MO-CCCII (multiple output current controlled current conveyor), a zero-crossing detector (ZCD), and one resistor connected to fixed potential. The circuit provides the operating frequency up to 10 MHz with increased linearity and precision in processing of input voltage signal, with a very low harmonic distortion. The errors related to the signal processing and errors bound were investigated and provided in the paper. The PSpice simulations are depicted and agree well with the theoretical anticipation. The maximum power consumption of the converter is approximately 2.83 mW, at ±1.2 V supply voltages.

Programmable Electrochemical Rectifier Based on a Thin-Layer Cell.

PubMed

Park, Seungjin; Park, Jun Hui; Hwang, Seongpil; Kwak, Juhyoun

2017-06-21

A programmable electrochemical rectifier based on thin-layer electrochemistry is described here. Both the rectification ratio and the response time of the device are programmable by controlling the gap distance of the thin-layer electrochemical cell, which is easily controlled using commercially available beads. One of the electrodes was modified using a ferrocene-terminated self-assembled monolayer to offer unidirectional charge transfers via soluble redox species. The thin-layer configuration provided enhanced mass transport, which was determined by the gap thickness. The device with the smallest gap thickness (∼4 μm) showed an unprecedented, high rectification ratio (up to 160) with a fast response time in a two-terminal configuration using conventional electronics.

Formation of porous silicon oxide from substrate-bound silicon rich silicon oxide layers by continuous-wave laser irradiation

NASA Astrophysics Data System (ADS)

Wang, Nan; Fricke-Begemann, Th.; Peretzki, P.; Ihlemann, J.; Seibt, M.

2018-03-01

Silicon nanocrystals embedded in silicon oxide that show room temperature photoluminescence (PL) have great potential in silicon light emission applications. Nanocrystalline silicon particle formation by laser irradiation has the unique advantage of spatially controlled heating, which is compatible with modern silicon micro-fabrication technology. In this paper, we employ continuous wave laser irradiation to decompose substrate-bound silicon-rich silicon oxide films into crystalline silicon particles and silicon dioxide. The resulting microstructure is studied using transmission electron microscopy techniques with considerable emphasis on the formation and properties of laser damaged regions which typically quench room temperature PL from the nanoparticles. It is shown that such regions consist of an amorphous matrix with a composition similar to silicon dioxide which contains some nanometric silicon particles in addition to pores. A mechanism referred to as "selective silicon ablation" is proposed which consistently explains the experimental observations. Implications for the damage-free laser decomposition of silicon-rich silicon oxides and also for controlled production of porous silicon dioxide films are discussed.

Boosting the signal: Endothelial inward rectifier K+ channels.

PubMed

Jackson, William F

2017-04-01

Endothelial cells express a diverse array of ion channels including members of the strong inward rectifier family composed of K IR 2 subunits. These two-membrane spanning domain channels are modulated by their lipid environment, and exist in macromolecular signaling complexes with receptors, protein kinases and other ion channels. Inward rectifier K + channel (K IR ) currents display a region of negative slope conductance at membrane potentials positive to the K + equilibrium potential that allows outward current through the channels to be activated by membrane hyperpolarization, permitting K IR to amplify hyperpolarization induced by other K + channels and ion transporters. Increases in extracellular K + concentration activate K IR allowing them to sense extracellular K + concentration and transduce this change into membrane hyperpolarization. These properties position K IR to participate in the mechanism of action of hyperpolarizing vasodilators and contribute to cell-cell conduction of hyperpolarization along the wall of microvessels. The expression of K IR in capillaries in electrically active tissues may allow K IR to sense extracellular K + , contributing to functional hyperemia. Understanding the regulation of expression and function of microvascular endothelial K IR will improve our understanding of the control of blood flow in the microcirculation in health and disease and may provide new targets for the development of therapeutics in the future. © 2016 John Wiley & Sons Ltd.

Software-defined networking control plane for seamless integration of multiple silicon photonic switches in Datacom networks.

PubMed

Shen, Yiwen; Hattink, Maarten H N; Samadi, Payman; Cheng, Qixiang; Hu, Ziyiz; Gazman, Alexander; Bergman, Keren

2018-04-16

Silicon photonics based switches offer an effective option for the delivery of dynamic bandwidth for future large-scale Datacom systems while maintaining scalable energy efficiency. The integration of a silicon photonics-based optical switching fabric within electronic Datacom architectures requires novel network topologies and arbitration strategies to effectively manage the active elements in the network. We present a scalable software-defined networking control plane to integrate silicon photonic based switches with conventional Ethernet or InfiniBand networks. Our software-defined control plane manages both electronic packet switches and multiple silicon photonic switches for simultaneous packet and circuit switching. We built an experimental Dragonfly network testbed with 16 electronic packet switches and 2 silicon photonic switches to evaluate our control plane. Observed latencies occupied by each step of the switching procedure demonstrate a total of 344 µs control plane latency for data-center and high performance computing platforms.

Optics to rectify CORONA panoramic photographs for map making

NASA Astrophysics Data System (ADS)

Hilbert, Robert S.

2006-08-01

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

Solid state thermal rectifier

DOEpatents

None

2016-07-05

Thermal rectifiers using linear nanostructures as core thermal conductors have been fabricated. A high mass density material is added preferentially to one end of the nanostructures to produce an axially non-uniform mass distribution. The resulting nanoscale system conducts heat asymmetrically with greatest heat flow in the direction of decreasing mass density. Thermal rectification has been demonstrated for linear nanostructures that are electrical insulators, such as boron nitride nanotubes, and for nanostructures that are conductive, such as carbon nanotubes.

Multibit Polycristalline Silicon-Oxide-Silicon Nitride-Oxide-Silicon Memory Cells with High Density Designed Utilizing a Separated Control Gate

NASA Astrophysics Data System (ADS)

Rok Kim, Kyeong; You, Joo Hyung; Dal Kwack, Kae; Kim, Tae Whan

2010-10-01

Unique multibit NAND polycrystalline silicon-oxide-silicon nitride-oxide-silicon (SONOS) memory cells utilizing a separated control gate (SCG) were designed to increase memory density. The proposed NAND SONOS memory device based on a SCG structure was operated as two bits, resulting in an increase in the storage density of the NVM devices in comparison with conventional single-bit memories. The electrical properties of the SONOS memory cells with a SCG were investigated to clarify the charging effects in the SONOS memory cells. When the program voltage was supplied to each gate of the NAND SONOS flash memory cells, the electrons were trapped in the nitride region of the oxide-nitride-oxide layer under the gate to supply the program voltage. The electrons were accumulated without affecting the other gate during the programming operation, indicating the absence of cross-talk between two trap charge regions. It is expected that the inference effect will be suppressed by the lower program voltage than the program voltage of the conventional NAND flash memory. The simulation results indicate that the proposed unique NAND SONOS memory cells with a SCG can be used to increase memory density.

Software-defined networking control plane for seamless integration of multiple silicon photonic switches in Datacom networks

DOE PAGES

Shen, Yiwen; Hattink, Maarten; Samadi, Payman; ...

2018-04-13

Silicon photonics based switches offer an effective option for the delivery of dynamic bandwidth for future large-scale Datacom systems while maintaining scalable energy efficiency. The integration of a silicon photonics-based optical switching fabric within electronic Datacom architectures requires novel network topologies and arbitration strategies to effectively manage the active elements in the network. Here, we present a scalable software-defined networking control plane to integrate silicon photonic based switches with conventional Ethernet or InfiniBand networks. Our software-defined control plane manages both electronic packet switches and multiple silicon photonic switches for simultaneous packet and circuit switching. We built an experimental Dragonfly networkmore » testbed with 16 electronic packet switches and 2 silicon photonic switches to evaluate our control plane. Observed latencies occupied by each step of the switching procedure demonstrate a total of 344 microsecond control plane latency for data-center and high performance computing platforms.« less

Software-defined networking control plane for seamless integration of multiple silicon photonic switches in Datacom networks

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

Shen, Yiwen; Hattink, Maarten; Samadi, Payman

Silicon photonics based switches offer an effective option for the delivery of dynamic bandwidth for future large-scale Datacom systems while maintaining scalable energy efficiency. The integration of a silicon photonics-based optical switching fabric within electronic Datacom architectures requires novel network topologies and arbitration strategies to effectively manage the active elements in the network. Here, we present a scalable software-defined networking control plane to integrate silicon photonic based switches with conventional Ethernet or InfiniBand networks. Our software-defined control plane manages both electronic packet switches and multiple silicon photonic switches for simultaneous packet and circuit switching. We built an experimental Dragonfly networkmore » testbed with 16 electronic packet switches and 2 silicon photonic switches to evaluate our control plane. Observed latencies occupied by each step of the switching procedure demonstrate a total of 344 microsecond control plane latency for data-center and high performance computing platforms.« less

Structural, Optical and Electrical Properties of ZnS/Porous Silicon Heterostructures

NASA Astrophysics Data System (ADS)

Wang, Cai-Feng; Li, Qing-Shan; Lv, Lei; Zhang, Li-Chun; Qi, Hong-Xia; Chen, Hou

2007-03-01

ZnS films are deposited by pulsed laser deposition on porous silicon (PS) substrates formed by electrochemical anodization of p-type (100) silicon wafer. Scanning electron microscope images reveal that the surface of ZnS films is unsmoothed, and there are some cracks in the ZnS films due to the roughness of the PS surface. The x-ray diffraction patterns show that the ZnS films on PS surface are grown in preferring orientation along cubic phase β-ZnS (111) direction. White light emission is obtained by combining the blue-green emission from ZnS films with the orange-red emission from PS layers. Based on the I-V characteristic, the ZnS/PS heterojunction exhibits the rectifying junction behaviour, and an ideality factor n is calculated to be 77 from the I-V plot.

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

PubMed Central

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

2014-01-01

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

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

PubMed

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

2014-01-01

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

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

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

Springer, J.; Allen, B.; Wriggins, W.

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 requirementmore » 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

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

NASA Astrophysics Data System (ADS)

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

2012-11-01

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

In-depth porosity control of mesoporous silicon layers by an anodization current adjustment

NASA Astrophysics Data System (ADS)

Lascaud, J.; Defforge, T.; Certon, D.; Valente, D.; Gautier, G.

2017-12-01

The formation of thick mesoporous silicon layers in P+-type substrates leads to an increase in the porosity from the surface to the interface with silicon. The adjustment of the current density during the electrochemical etching of porous silicon is an intuitive way to control the layer in-depth porosity. The duration and the current density during the anodization were varied to empirically model porosity variations with layer thickness and build a database. Current density profiles were extracted from the model in order to etch layer with in-depth control porosity. As a proof of principle, an 80 μm-thick porous silicon multilayer was synthetized with decreasing porosities from 55% to 35%. The results show that the assessment of the in-depth porosity could be significantly enhanced by taking into account the pure chemical etching of the layer in the hydrofluoric acid-based electrolyte.

Polycrystalline silicon availability for photovoltaic and semiconductor industries

NASA Technical Reports Server (NTRS)

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

1982-01-01

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

Fabrication and characterization of the organic rectifying junctions by electrolysis

NASA Astrophysics Data System (ADS)

Karimov, Khasan; Ahmad, Zubair; Ali, Rashid; Noor, Adnan; Akmal, M.; Najeeb, M. A.; Shakoor, R. A.

2017-08-01

Unlike the conventional solution processable deposition techniques, in this study, we propose a novel and economical method for the fabrication of organic rectifying junctions. The solutions of the orange dye, copper phthalocyanine and NaCl were deposited on the surface-type interdigitated silver electrodes using electrolysis technique. Using the current-voltage (I-V) characteristics, the presence of rectifying behavior in the samples has been confirmed. This phenomenon, in principle, can be used for fabrication of the diodes, transistors and memory devices.

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

PubMed

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

2013-02-25

We design a new type of molecular diode, based on the organoimido derivatives of hexamolybdates, by exploring the rectifying performances using density functional theory combined with the non-equilibrium Green's function. Asymmetric current-voltage characteristics were obtained for the models with an unexpected large rectification ratio. The rectifying behavior can be understood by the asymmetrical shift of the transmission peak observed under different polarities. It is interesting to find that the preferred electron-transport direction in our studied system is different from that of the organic D-bridge-A system. The results show that the studied organic-inorganic hybrid systems have an intrinsically robust rectifying ratio, which should be taken into consideration in the design of the molecular diodes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison between Phase-Shift Full-Bridge Converters with Noncoupled and Coupled Current-Doubler Rectifier

PubMed Central

Tsai, Cheng-Tao; Tseng, Sheng-Yu

2013-01-01

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications. PMID:24381521

Comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier.

PubMed

Tsai, Cheng-Tao; Su, Jye-Chau; Tseng, Sheng-Yu

2013-01-01

This paper presents comparison between phase-shift full-bridge converters with noncoupled and coupled current-doubler rectifier. In high current capability and high step-down voltage conversion, a phase-shift full-bridge converter with a conventional current-doubler rectifier has the common limitations of extremely low duty ratio and high component stresses. To overcome these limitations, a phase-shift full-bridge converter with a noncoupled current-doubler rectifier (NCDR) or a coupled current-doubler rectifier (CCDR) is, respectively, proposed and implemented. In this study, performance analysis and efficiency obtained from a 500 W phase-shift full-bridge converter with two improved current-doubler rectifiers are presented and compared. From their prototypes, experimental results have verified that the phase-shift full-bridge converter with NCDR has optimal duty ratio, lower component stresses, and output current ripple. In component count and efficiency comparison, CCDR has fewer components and higher efficiency at full load condition. For small size and high efficiency requirements, CCDR is relatively suitable for high step-down voltage and high efficiency applications.

Failure Detecting Method of Fault Current Limiter System with Rectifier

NASA Astrophysics Data System (ADS)

Tokuda, Noriaki; Matsubara, Yoshio; Asano, Masakuni; Ohkuma, Takeshi; Sato, Yoshibumi; Takahashi, Yoshihisa

A fault current limiter (FCL) is extensively needed to suppress fault current, particularly required for trunk power systems connecting high-voltage transmission lines, such as 500kV class power system which constitutes the nucleus of the electric power system. We proposed a new type FCL system (rectifier type FCL), consisting of solid-state diodes, DC reactor and bypass AC reactor, and demonstrated the excellent performances of this FCL by developing the small 6.6kV and 66kV model. It is important to detect the failure of power devices used in the rectifier under the normal operating condition, for keeping the excellent reliability of the power system. In this paper, we have proposed a new failure detecting method of power devices most suitable for the rectifier type FCL. This failure detecting system is simple and compact. We have adapted the proposed system to the 66kV prototype single-phase model and successfully demonstrated to detect the failure of power devices.

Fast switching wideband rectifying circuit for future RF energy harvesting

NASA Astrophysics Data System (ADS)

Asmeida, Akrem; Mustam, Saizalmursidi Md; Abidin, Z. Z.; Ashyap, A. Y. I.

2017-09-01

This paper presents the design and simulation of fast switching microwave rectifying circuit for ultra wideband patch antenna over a dual-frequency band (1.8 GHz for GSM and 2.4 GHz for ISM band). This band was chosen due to its high signal availability in the surrounding environment. New rectifying circuit topology with pair-matching trunks is designed using Advanced Design System (ADS) software. These trunks are interfaced with power divider to achieve good bandwidth, fast switching and high efficiency. The power divider acts as a good isolator between the trunks and its straightforward design structure makes it a good choice for a single feed UWB antenna. The simulated results demonstrate that the maximum output voltage is 2.13 V with an input power of -5 dBm. Moreover, the rectifier offers maximum efficiency of 86% for the input power of -5 dBm at given band, which could easily power up wireless sensor networks (WSN) and other small devices sufficiently.

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

PubMed

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

2012-08-01

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 μm 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.

Design and test of a 2.25-MW transformer rectifier assembly

NASA Technical Reports Server (NTRS)

Cormier, R.; Daeges, J.

1989-01-01

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

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Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-05

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

NASA Astrophysics Data System (ADS)

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

2014-08-01

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

Humidity sensing properties of morphology-controlled ordered silicon nanopillar

NASA Astrophysics Data System (ADS)

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

2014-10-01

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

Competitive inhibition can linearize dose-response and generate a linear rectifier.

PubMed

Savir, Yonatan; Tu, Benjamin P; Springer, Michael

2015-09-23

Many biological responses require a dynamic range that is larger than standard bi-molecular interactions allow, yet the also ability to remain off at low input. Here we mathematically show that an enzyme reaction system involving a combination of competitive inhibition, conservation of the total level of substrate and inhibitor, and positive feedback can behave like a linear rectifier-that is, a network motif with an input-output relationship that is linearly sensitive to substrate above a threshold but unresponsive below the threshold. We propose that the evolutionarily conserved yeast SAGA histone acetylation complex may possess the proper physiological response characteristics and molecular interactions needed to perform as a linear rectifier, and we suggest potential experiments to test this hypothesis. One implication of this work is that linear responses and linear rectifiers might be easier to evolve or synthetically construct than is currently appreciated.

Nanostructured silicon membranes for control of molecular transport.

PubMed

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

2010-11-01

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

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

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

Programmable controller system for wind tunnel diversion vanes

NASA Technical Reports Server (NTRS)

King, R. F.

1982-01-01

A programmable controller (PC) system automatic sequence control, which acts as a supervisory controller for the servos, selects the proper drives, and automatically sequences the vanes, was developed for use in a subsonic wind tunnel. Tunnel modifications include a new second test section (80 ft x 100 ft with a maximum air speed capability of 110 knots) and an increase in maximum velocity flow from 200 knots to 300 knots. A completely automatic sequence control is necessary in order to allow intricate motion of the 14 triangularly arranged vanes which can be as large as 70 ft high x 35 ft wide and which require precise acceleration and deceleration control. Rate servos on each drive aid in this control, and servo cost was minimized by using four silicon controlled rectifier controllers to control the 20 dc drives. The PC has a programming capacity which facilitated the implementation of extensive logic design. A series of diagrams sequencing the vanes and a block diagram of the system are included.

Development of a Thermal Rectifier Usable at High Temperature

NASA Astrophysics Data System (ADS)

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

2011-05-01

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.

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

NASA Technical Reports Server (NTRS)

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

1990-01-01

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

Understanding and controlling the step bunching instability in aqueous silicon etching

NASA Astrophysics Data System (ADS)

Bao, Hailing

Chemical etching of silicon has been widely used for more than half a century in the semiconductor industry. It not only forms the basis for current wafer cleaning processes, it also serves as a powerful tool to create a variety of surface morphologies for different applications. Its potential for controlling surface morphology at the atomic scale over micron-size regions is especially appealing. In spite of its wide usage, the chemistry of silicon etching is poorly understood. Many seemingly simple but fundamental questions have not been answered. As a result, the development of new etchants and new etching protocols are based on expensive and tedious trial-and-error experiments. A better understanding of the etching mechanism would direct the rational formulation of new etchants that produce controlled etch morphologies. Particularly, micron-scale step bunches spontaneously develop on the vicinal Si(111) surface etched in KOH or other anisotropic aqueous etchants. The ability to control the size, orientation, density and regularity of these surface features would greatly improve the performance of microelectromechanical devices. This study is directed towards understanding the chemistry and step bunching instability in aqueous anisotropic etching of silicon through a combination of experimental techniques and theoretical simulations. To reveal the cause of step-bunching instability, kinetic Monte Carlo simulations were constructed based on an atomistic model of the silicon lattice and a modified kinematic wave theory. The simulations showed that inhomogeneity was the origin of step-bunching, which was confirmed through STM studies of etch morphologies created under controlled flow conditions. To quantify the size of the inhomogeneities in different etchants and to clarify their effects, a five-parallel-trench pattern was fabricated. This pattern used a nitride mask to protect most regions of the wafer; five evenly spaced etch windows were opened to the Si(110

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

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

Onar, Omer C; Tang, Lixin; Chinthavali, Madhu Sudhan

2014-01-01

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

Spectroscopic ellipsometry analysis of nanocrystalline silicon carbide obtained at low temperature

NASA Astrophysics Data System (ADS)

Kerdiles, S.; Madelon, R.; Rizk, R.

2001-12-01

Thin films of silicon carbide obtained by hydrogen-reactive magnetron sputtering with various substrate temperatures TS (100-600 °C) were analysed by transmission electron microscopy (TEM) and spectroscopic ellipsometry (SE). The TEM images show evidence of the growth of hydrogenated nanocrystalline silicon carbide (nc-SiC:H) deposited at TS as low as 300 °C, with an average grain size of 4-5 nm. The SE spectra were reproduced by using the Forouhi-Bloomer model and assuming a 7 nm thick overlayer with a void fraction of 45%. The observed increase of the refractive index with TS is assigned to the improvement of both crystallinity and compactness of the layer. The expected increase of the optical gap seems to be offset by the drop of hydrogen content, leaving the gap unchanged. The fabrication and characteristics of nc-SiC:H/c-Si diode are finally described and the data indicate a good rectifying behaviour, together with a low leakage current.

Delayed rectifier potassium channels are involved in SO2 derivative-induced hippocampal neuronal injury.

PubMed

Li, Guangke; Sang, Nan

2009-01-01

Recent studies implicate the possible neurotoxicity of SO(2), however, its mechanisms remain unclear. In the present study, we investigated SO(2) derivative-induced effect on delayed rectifier potassium channels (I(K)) and cellular death/apoptosis in primary cultured hippocampal neurons. The results demonstrate that SO(2) derivatives (NaHSO(3) and Na(2)SO(3), 3:1M/M) effectively augmented I(K) and promoted the activation of delayed rectifier potassium channels. Also, SO(2) derivatives increased neuronal death percentage and contributed to the formation of DNA ladder in concentration-dependent manners. Interestingly, the neuronal death and DNA ladder formation, caused by SO(2) derivatives, could be attenuated by the delayed rectifier potassium channel blocker (tetraethylammonium, TEA), but not by the transient outward potassium channel blocker (4-aminopyridine, 4-AP). It implies that stimulating delayed rectifier potassium channels were involved in SO(2) derivative-caused hippocampal neuronal insults, and blocking these channels might be one of the possibly clinical treatment for SO(2)-caused neuronal dysfunction.

Inhibition of the cardiac inward rectifier potassium currents by KB-R7943.

PubMed

Abramochkin, Denis V; Alekseeva, Eugenia I; Vornanen, Matti

2013-09-01

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. © 2013.

Energy-harvesting shock absorber with a mechanical motion rectifier

NASA Astrophysics Data System (ADS)

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

2013-02-01

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.

A self-powered piezoelectric energy harvesting interface circuit with efficiency-enhanced P-SSHI rectifier

NASA Astrophysics Data System (ADS)

Liu, Lianxi; Pang, Yanbo; Yuan, Wenzhi; Zhu, Zhangming; Yang, Yintang

2018-04-01

The key to self-powered technique is initiative to harvest energy from the surrounding environment. Harvesting energy from an ambient vibration source utilizing piezoelectrics emerged as a popular method. Efficient interface circuits become the main limitations of existing energy harvesting techniques. In this paper, an interface circuit for piezoelectric energy harvesting is presented. An active full bridge rectifier is adopted to improve the power efficiency by reducing the conduction loss on the rectifying path. A parallel synchronized switch harvesting on inductor (P-SSHI) technique is used to improve the power extraction capability from piezoelectric harvester, thereby trying to reach the theoretical maximum output power. An intermittent power management unit (IPMU) and an output capacitor-less low drop regulator (LDO) are also introduced. Active diodes (AD) instead of traditional passive ones are used to reduce the voltage loss over the rectifier, which results in a good power efficiency. The IPMU with hysteresis comparator ensures the interface circuit has a large transient output power by limiting the output voltage ranges from 2.2 to 2 V. The design is fabricated in a SMIC 0.18 μm CMOS technology. Simulation results show that the flipping efficiency of the P-SSHI circuit is over 80% with an off-chip inductor value of 820 μH. The output power the proposed rectifier can obtain is 44.4 μW, which is 6.7× improvement compared to the maximum output power of a traditional rectifier. Both the active diodes and the P-SSHI help to improve the output power of the proposed rectifier. LDO outputs a voltage of 1.8 V with the maximum 90% power efficiency. The proposed P-SSHI rectifier interface circuit can be self-powered without the need for additional power supply. Project supported by the National Natural Science Foundation of China (Nos. 61574103, U1709218) and the Key Research and Development Program of Shaanxi Province (No. 2017ZDXM-GY-006).

Reconfigurable Resonant Regulating Rectifier With Primary Equalization for Extended Coupling- and Loading-Range in Bio-Implant Wireless Power Transfer.

PubMed

Li, Xing; Meng, Xiaodong; Tsui, Chi-Ying; Ki, Wing-Hung

2015-12-01

Wireless power transfer using reconfigurable resonant regulating (R(3)) rectification suffers from limited range in accommodating varying coupling and loading conditions. A primary-assisted regulation principle is proposed to mitigate these limitations, of which the amplitude of the rectifier input voltage on the secondary side is regulated by accordingly adjusting the voltage amplitude Veq on the primary side. A novel current-sensing method and calibration scheme track Veq on the primary side. A ramp generator simultaneously provides three clock signals for different modules. Both the primary equalizer and the R(3) rectifier are implemented as custom integrated circuits fabricated in a 0.35 μm CMOS process, with the global control implemented in FPGA. Measurements show that with the primary equalizer, the workable coupling and loading ranges are extended by 250% at 120 mW load and 300% at 1.2 cm coil distance compared to the same system without the primary equalizer. A maximum rectifier efficiency of 92.5% and a total system efficiency of 62.4% are demonstrated.

Self-Rectifying Effect in Resistive Switching Memory Using Amorphous InGaZnO

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Controlling the spectrum of photons generated on a silicon nanophotonic chip

PubMed Central

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

2014-01-01

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

Inward rectifier potassium channels in the HL-1 cardiomyocyte-derived cell line.

PubMed

Goldoni, Dana; Zhao, YouYou; Green, Brian D; McDermott, Barbara J; Collins, Anthony

2010-11-01

HL-1 is a line of immortalized cells of cardiomyocyte origin that are a useful complement to native cardiomyocytes in studies of cardiac gene regulation. Several types of ion channel have been identified in these cells, but not the physiologically important inward rectifier K(+) channels. Our aim was to identify and characterize inward rectifier K(+) channels in HL-1 cells. External Ba(2+) (100 µM) inhibited 44 ± 0.05% (mean ± s.e.m., n = 11) of inward current in whole-cell patch-clamp recordings. The reversal potential of the Ba(2+)-sensitive current shifted with external [K(+)] as expected for K(+)-selective channels. The slope conductance of the inward Ba(2+)-sensitive current increased with external [K(+)]. The apparent Kd for Ba(2+) was voltage dependent, ranging from 15 µM at -150  mV to 148 µM at -75  mV in 120  mM external K(+). This current was insensitive to 10 µM glybenclamide. A component of whole-cell current was sensitive to 150 µM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), although it did not correspond to the Ba(2+)-sensitive component. The effect of external 1 mM Cs(+) was similar to that of Ba(2+). Polymerase chain reaction using HL-1 cDNA as template and primers specific for the cardiac inward rectifier K(ir)2.1 produced a fragment of the expected size that was confirmed to be K(ir)2.1 by DNA sequencing. In conclusion, HL-1 cells express a current that is characteristic of cardiac inward rectifier K(+) channels, and express K(ir)2.1 mRNA. This cell line may have use as a system for studying inward rectifier gene regulation in a cardiomyocyte phenotype. © 2010 Wiley-Liss, Inc.

Rectifying the output of vibrational piezoelectric energy harvester using quantum dots

NASA Astrophysics Data System (ADS)

Li, Lijie

2017-03-01

Piezoelectric energy harvester scavenges mechanical vibrations and generates electricity. Researchers have strived to optimize the electromechanical structures and to design necessary external power management circuits, aiming to deliver high power and rectified outputs ready for serving as batteries. Complex deformation of the mechanical structure results in charges with opposite polarities appearing on same surface, leading to current loss in the attached metal electrode. External power management circuits such as rectifiers comprise diodes that consume power and have undesirable forward bias. To address the above issues, we devise a novel integrated piezoelectric energy harvesting device that is structured by stacking a layer of quantum dots (QDs) and a layer of piezoelectric material. We find that the QD can rectify electrical charges generated from the piezoelectric material because of its adaptable conductance to the electrochemical potentials of both sides of the QDs layer, so that electrical current causing energy loss on the same surface of the piezoelectric material can be minimized. The QDs layer has the potential to replace external rectification circuits providing a much more compact and less power-consumption solution.

Possibility designing half-wave and full-wave molecular rectifiers by using single benzene molecule

NASA Astrophysics Data System (ADS)

Abbas, Mohammed A.; Hanoon, Falah H.; Al-Badry, Lafy F.

2018-02-01

This work focused on possibility designing half-wave and full-wave molecular rectifiers by using single and two benzene rings, respectively. The benzene rings were threaded by a magnetic flux that changes over time. The quantum interference effect was considered as the basic idea in the rectification action, the para and meta configurations were investigated. All the calculations are performed by using steady-state theoretical model, which is based on the time-dependent Hamiltonian model. The electrical conductance and the electric current are considered as DC output signals of half-wave and full-wave molecular rectifiers. The finding in this work opens up the exciting potential to use these molecular rectifiers in molecular electronics.

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

NASA Astrophysics Data System (ADS)

Wang, Chenlei

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

Site-Controlled Growth of Monolithic InGaAs/InP Quantum Well Nanopillar Lasers on Silicon.

PubMed

Schuster, Fabian; Kapraun, Jonas; Malheiros-Silveira, Gilliard N; Deshpande, Saniya; Chang-Hasnain, Connie J

2017-04-12

In this Letter, we report the site-controlled growth of InP nanolasers on a silicon substrate with patterned SiO 2 nanomasks by low-temperature metal-organic chemical vapor deposition, compatible with silicon complementary metal-oxide-semiconductor (CMOS) post-processing. A two-step growth procedure is presented to achieve smooth wurtzite faceting of vertical nanopillars. By incorporating InGaAs multiquantum wells, the nanopillar emission can be tuned over a wide spectral range. Enhanced quality factors of the intrinsic InP nanopillar cavities promote lasing at 0.87 and 1.21 μm, located within two important optical telecommunication bands. This is the first demonstration of a site-controlled III-V nanolaser monolithically integrated on silicon with a silicon-transparent emission wavelength, paving the way for energy-efficient on-chip optical links at typical telecommunication wavelengths.

A high speed PE-ALD ZnO Schottky diode rectifier with low interface-state density

NASA Astrophysics Data System (ADS)

Jin, Jidong; Zhang, Jiawei; Shaw, Andrew; Kudina, Valeriya N.; Mitrovic, Ivona Z.; Wrench, Jacqueline S.; Chalker, Paul R.; Balocco, Claudio; Song, Aimin; Hall, Steve

2018-02-01

Zinc oxide (ZnO) has recently attracted attention for its potential application to high speed electronics. In this work, a high speed Schottky diode rectifier was fabricated based on a ZnO thin film deposited by plasma-enhanced atomic layer deposition and a PtOx Schottky contact deposited by reactive radio-frequency sputtering. The rectifier shows an ideality factor of 1.31, an effective barrier height of 0.79 eV, a rectification ratio of 1.17  ×  107, and cut-off frequency as high as 550 MHz. Low frequency noise measurements reveal that the rectifier has a low interface-state density of 5.13  ×  1012 cm-2 eV-1, and the noise is dominated by the mechanism of a random walk of electrons at the PtO x /ZnO interface. The work shows that the rectifier can be used for both noise sensitive and high frequency electronics applications.

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

PubMed

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

1995-04-01

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

Confined in-fiber solidification and structural control of silicon and silicon−germanium microparticles

PubMed Central

Gumennik, Alexander; Levy, Etgar C.; Grena, Benjamin; Hou, Chong; Rein, Michael; Abouraddy, Ayman F.; Joannopoulos, John D.; Fink, Yoel

2017-01-01

Crystallization of microdroplets of molten alloys could, in principle, present a number of possible morphological outcomes, depending on the symmetry of the propagating solidification front and its velocity, such as axial or spherically symmetric species segregation. However, because of thermal or constitutional supercooling, resulting droplets often only display dendritic morphologies. Here we report on the crystallization of alloyed droplets of controlled micrometer dimensions comprising silicon and germanium, leading to a number of surprising outcomes. We first produce an array of silicon−germanium particles embedded in silica, through capillary breakup of an alloy-core silica-cladding fiber. Heating and subsequent controlled cooling of individual particles with a two-wavelength laser setup allows us to realize two different morphologies, the first being a silicon−germanium compositionally segregated Janus particle oriented with respect to the illumination axis and the second being a sphere made of dendrites of germanium in silicon. Gigapascal-level compressive stresses are measured within pure silicon solidified in silica as a direct consequence of volume-constrained solidification of a material undergoing anomalous expansion. The ability to generate microspheres with controlled morphology and unusual stresses could pave the way toward advanced integrated in-fiber electronic or optoelectronic devices. PMID:28642348

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

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

Ning, Puqi; Wang, Ruxi; Wang, Fei

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.

Enhancement of delayed-rectifier potassium conductance by low concentrations of local anaesthetics in spinal sensory neurones

PubMed Central

Olschewski, Andrea; Wolff, Matthias; Bräu, Michael E; Hempelmann, Gunter; Vogel, Werner; Safronov, Boris V

2002-01-01

Combining the patch-clamp recordings in slice preparation with the ‘entire soma isolation' method we studied action of several local anaesthetics on delayed-rectifier K+ currents in spinal dorsal horn neurones.Bupivacaine, lidocaine and mepivacaine at low concentrations (1–100 μM) enhanced delayed-rectifier K+ current in intact neurones within the spinal cord slice, while exhibiting a partial blocking effect at higher concentrations (>100 μM). In isolated somata 0.1–10 μM bupivacaine enhanced delayed-rectifier K+ current by shifting its steady-state activation characteristic and the voltage-dependence of the activation time constant to more negative potentials by 10–20 mV.Detailed analysis has revealed that bupivacaine also increased the maximum delayed-rectifier K+ conductance by changing the open probability, rather than the unitary conductance, of the channel.It is concluded that local anaesthetics show a dual effect on delayed-rectifier K+ currents by potentiating them at low concentrations and partially suppressing at high concentrations. The phenomenon observed demonstrated the complex action of local anaesthetics during spinal and epidural anaesthesia, which is not restricted to a suppression of Na+ conductance only. PMID:12055132

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

PubMed

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

2015-05-07

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

Controllable nonlinear refraction characteristics in hydrogenated nanocrystalline silicon

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

Zheng, D. Q.; Ye, Q. H.; Shen, W. Z., E-mail: wzshen@sjtu.edu.cn

2014-02-07

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

The Usefulness of Rectified VEMP.

PubMed

Lee, Kang Jin; Kim, Min Soo; Son, Eun Jin; Lim, Hye Jin; Bang, Jung Hwan; Kang, Jae Goo

2008-09-01

For a reliable interpretation of left-right difference in Vestibular evoked myogenic potential (VEMP), the amount of sternocleidomastoid muscle (SCM) contraction has to be considered. Therefore, we can ensure that a difference in amplitude between the right and left VEMPs on a patient is due to vestibular abnormality, not due to individual differences of tonic muscle activity, fatigue or improper position. We used rectification to normalize electromyograph (EMG) based on pre-stimulus EMG activity. This study was designed to evaluate and compare the effect of rectification in two conventional ways of SCM contraction. Twenty-two normal subjects were included. Two methods were employed for SCM contraction in a subject. First, subjects were made to lie flat on their back, lifting the head off the table and turning to the opposite side. Secondly, subjects push with their jaw against the hand-held inflated cuff to generate cuff pressure of 40 mmHg. From the VEMP graphs, amplitude parameters and inter-aural difference ratio (IADR) were analyzed before and after EMG rectification. Before the rectification, the average IADR of the first method was not statistically different from that of the second method. The average IADRs from each method decreased in a rectified response, showing significant reduction in asymmetry ratio. The lowest average IADR could be obtained with the combination of both the first method and rectification. Rectified data show more reliable IADR and may help diagnose some vestibular disorders according to amplitude-associated parameters. The usage of rectification can be maximized with the proper SCM contraction method.

The Usefulness of Rectified VEMP

PubMed Central

Kim, Min Soo; Son, Eun Jin; Lim, Hye Jin; Bang, Jung Hwan; Kang, Jae Goo

2008-01-01

Objectives For a reliable interpretation of left-right difference in Vestibular evoked myogenic potential (VEMP), the amount of sternocleidomastoid muscle (SCM) contraction has to be considered. Therefore, we can ensure that a difference in amplitude between the right and left VEMPs on a patient is due to vestibular abnormality, not due to individual differences of tonic muscle activity, fatigue or improper position. We used rectification to normalize electromyograph (EMG) based on pre-stimulus EMG activity. This study was designed to evaluate and compare the effect of rectification in two conventional ways of SCM contraction. Methods Twenty-two normal subjects were included. Two methods were employed for SCM contraction in a subject. First, subjects were made to lie flat on their back, lifting the head off the table and turning to the opposite side. Secondly, subjects push with their jaw against the hand-held inflated cuff to generate cuff pressure of 40 mmHg. From the VEMP graphs, amplitude parameters and inter-aural difference ratio (IADR) were analyzed before and after EMG rectification. Results Before the rectification, the average IADR of the first method was not statistically different from that of the second method. The average IADRs from each method decreased in a rectified response, showing significant reduction in asymmetry ratio. The lowest average IADR could be obtained with the combination of both the first method and rectification. Conclusion Rectified data show more reliable IADR and may help diagnose some vestibular disorders according to amplitude-associated parameters. The usage of rectification can be maximized with the proper SCM contraction method. PMID:19434246

Remotely-actuated biomedical switch

NASA Technical Reports Server (NTRS)

Lee, R. D.

1969-01-01

Remotely-actuated biomedical switching circuit using transistors consumes no power in the off position and can be actuated by a single-frequency telemetry pulse to control implanted instrumentation. Silicon controlled rectifiers permit the circuit design which imposes zero drain on supply batteries when not in use.

Energy-Saving Inverter

NASA Technical Reports Server (NTRS)

Rippel, W. E.; Edwards, D. B.

1984-01-01

Commutation by field-effect transistor allows more efficient operation. High voltage field-effect transistor (FET) controls silicon controlled rectifiers (SCR's). Circuit requires only one capacitor and one inductor in commutation circuit: simpler, more efficient, and more economical than conventional inverters. Adaptable to dc-to-dc converters.

High-voltage 4H-SiC trench MOS barrier Schottky rectifier with low forward voltage drop using enhanced sidewall layer

NASA Astrophysics Data System (ADS)

Cho, Doohyung; Sim, Seulgi; Park, Kunsik; Won, Jongil; Kim, Sanggi; Kim, Kwangsoo

2015-12-01

In this paper, a 4H-SiC trench MOS barrier Schottky (TMBS) rectifier with an enhanced sidewall layer (ESL) is proposed. The proposed structure has a high doping concentration at the trench sidewall. This high doping concentration improves both the reverse blocking and forward characteristics of the structure. The ESL-TMBS rectifier has a 7.4% lower forward voltage drop and a 24% higher breakdown voltage. However, this structure has a reverse leakage current that is approximately three times higher than that of a conventional TMBS rectifier owing to the reduction in energy barrier height. This problem is solved when ESL is used partially, since its use provides a reverse leakage current that is comparable to that of a conventional TMBS rectifier. Thus, the forward voltage drop and breakdown voltage improve without any loss in static and dynamic characteristics in the ESL-TMBS rectifier compared with the performance of a conventional TMBS rectifier.

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

DOEpatents

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

1980-08-26

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

Study on Silicon Microstructure Processing Technology Based on Porous Silicon

NASA Astrophysics Data System (ADS)

Shang, Yingqi; Zhang, Linchao; Qi, Hong; Wu, Yalin; Zhang, Yan; Chen, Jing

2018-03-01

Aiming at the heterogeneity of micro - sealed cavity in silicon microstructure processing technology, the technique of preparing micro - sealed cavity of porous silicon is proposed. The effects of different solutions, different substrate doping concentrations, different current densities, and different etching times on the rate, porosity, thickness and morphology of the prepared porous silicon were studied. The porous silicon was prepared by different process parameters and the prepared porous silicon was tested and analyzed. For the test results, optimize the process parameters and experiments. The experimental results show that the porous silicon can be controlled by optimizing the parameters of the etching solution and the doping concentration of the substrate, and the preparation of porous silicon with different porosity can be realized by different doping concentration, so as to realize the preparation of silicon micro-sealed cavity, to solve the sensor sensitive micro-sealed cavity structure heterogeneous problem, greatly increasing the application of the sensor.

Multi-Service Highly Sensitive Rectifier for Enhanced RF Energy Scavenging

PubMed Central

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

2015-01-01

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

Rectifying Social Inequalities in a Resource Allocation Task

PubMed Central

Elenbaas, Laura; Rizzo, Michael T.; Cooley, Shelby; Killen, Melanie

2016-01-01

To investigate whether children rectify social inequalities in a resource allocation task, participants (N = 185 African-American and European-American 5–6 year-olds and 10–11 year-olds) witnessed an inequality of school supplies between peers of different racial backgrounds. Assessments were conducted on how children judged the wrongfulness of the inequality, allocated new resources to racial ingroup and outgroup recipients, evaluated alternative allocation strategies, and reasoned about their decisions. Younger children showed ingroup favorability; their responses differed depending on whether they had witnessed their ingroup or an outgroup at a disadvantage. With age, children increasingly reasoned about the importance of equal access to school supplies and correcting past disparities. Older children judged the resource inequality negatively, allocated more resources to the disadvantaged group, and positively evaluated the actions of others who did the same, regardless of whether they had seen their racial ingroup or an outgroup at a disadvantage. Thus, balancing moral and social group concerns enabled individuals to rectify inequalities and ensure fair access to important resources regardless of racial group membership. PMID:27423813

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

PubMed

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

2013-01-01

A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2 m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200 μm and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump.

Molecular Basis of Cardiac Delayed Rectifier Potassium Channel Function and Pharmacology.

PubMed

Wu, Wei; Sanguinetti, Michael C

2016-06-01

Human cardiomyocytes express 3 distinct types of delayed rectifier potassium channels. Human ether-a-go-go-related gene (hERG) channels conduct the rapidly activating current IKr; KCNQ1/KCNE1 channels conduct the slowly activating current IKs; and Kv1.5 channels conduct an ultrarapid activating current IKur. Here the authors provide a general overview of the mechanistic and structural basis of ion selectivity, gating, and pharmacology of the 3 types of cardiac delayed rectifier potassium ion channels. Most blockers bind to S6 residues that line the central cavity of the channel, whereas activators interact with the channel at 4 symmetric binding sites outside the cavity. Copyright © 2016 Elsevier Inc. All rights reserved.

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

NASA Technical Reports Server (NTRS)

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

2001-01-01

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

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

NASA Technical Reports Server (NTRS)

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

2000-01-01

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

Vascular Inward Rectifier K+ Channels as External K+ Sensors in the Control of Cerebral Blood Flow

PubMed Central

LONGDEN, THOMAS A.; NELSON, MARK T.

2015-01-01

For decades it has been known that external potassium (K+) ions are rapid and potent vasodilators that increase cerebral blood flow (CBF). Recent studies have implicated the local release of K+ from astrocytic endfeet—which encase the entirety of the parenchymal vasculature—in the dynamic regulation of local CBF during neurovascular coupling (NVC). It has been proposed that the activation of strong inward rectifier K+ (KIR) channels in the vascular wall by external K+ is a central component of these hyperemic responses; however, a number of significant gaps in our knowledge remain. Here, we explore the concept that vascular KIR channels are the major extracellular K+ sensors in the control of CBF. We propose that K+ is an ideal mediator of NVC, and discuss KIR channels as effectors that produce rapid hyperpolarization and robust vasodilation of cerebral arterioles. We provide evidence that KIR channels, of the KIR2 subtype in particular, are present in both the endothelial and smooth muscle cells of parenchymal arterioles and propose that this dual positioning of KIR2 channels increases the robustness of the vasodilation to external K+, enables the endothelium to be actively engaged in neurovascular coupling, and permits electrical signaling through the endothelial syncytium to promote upstream vasodilation to modulate CBF. PMID:25641345

Energy Harvesting from Energetic Porous Silicon

DTIC Science & Technology

2016-07-01

ignition. Here we investigate a means to convert this mechanical energy to electrical energy via a piezoelectric cantilever and rectifying circuit. This...mechanical energy to electrical energy via a piezoelectric cantilever and an associated rectifying circuit. A small PSi sample is placed on the...cantilever is wired to a direct current (DC) full-bridge rectifier circuit (EHE001NC) also purchased from Midé. Test points have been added at the

Photo-EMF sensitivity of porous silicon thin layer-crystalline silicon heterojunction to ammonia adsorption.

PubMed

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-01

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.

Photo-EMF Sensitivity of Porous Silicon Thin Layer–Crystalline Silicon Heterojunction to Ammonia Adsorption

PubMed Central

Vashpanov, Yuriy; Jung, Jae Il; Kwack, Kae Dal

2011-01-01

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

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

NASA Technical Reports Server (NTRS)

Gassaway, J. D.

1974-01-01

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

Power processor for a 20CM ion thruster

NASA Technical Reports Server (NTRS)

Biess, J. J.; Schoenfeld, A. D.; Cohen, E.

1973-01-01

A power processor breadboard for the JPL 20CM Ion Engine was designed, fabricated, and tested to determine compliance with the electrical specification. The power processor breadboard used the silicon-controlled rectifier (SCR) series resonant inverter as the basic power stage to process all the power to the ion engine. The breadboard power processor was integrated with the JPL 20CM ion engine and complete testing was performed. The integration tests were performed without any silicon-controlled rectifier failure. This demonstrated the ruggedness of the series resonant inverter in protecting the switching elements during arcing in the ion engine. A method of fault clearing the ion engine and returning back to normal operation without elaborate sequencing and timing control logic was evolved. In this method, the main vaporizer was turned off and the discharge current limit was reduced when an overload existed on the screen/accelerator supply. After the high voltage returned to normal, both the main vaporizer and the discharge were returned to normal.

Production of electronic grade lunar silicon by disproportionation of silicon difluoride

NASA Technical Reports Server (NTRS)

Agosto, William N.

1993-01-01

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

Fabricating and Controlling Silicon Zigzag Nanowires by Diffusion-Controlled Metal-Assisted Chemical Etching Method.

PubMed

Chen, Yun; Zhang, Cheng; Li, Liyi; Tuan, Chia-Chi; Wu, Fan; Chen, Xin; Gao, Jian; Ding, Yong; Wong, Ching-Ping

2017-07-12

Silicon (Si) zigzag nanowires (NWs) have a great potential in many applications because of its high surface/volume ratio. However, fabricating Si zigzag NWs has been challenging. In this work, a diffusion-controlled metal-assisted chemical etching method is developed to fabricate Si zigzag NWs. By tailoring the composition of etchant to change its diffusivity, etching direction, and etching time, various zigzag NWs can be easily fabricated. In addition, it is also found that a critical length of NW (>1 μm) is needed to form zigzag nanowires. Also, the amplitude of zigzag increases as the location approaches the center of the substrate and the length of zigzag nanowire increases. It is also demonstrated that such zigzag NWs can help the silicon substrate for self-cleaning and antireflection. This method may provide a feasible and economical way to fabricate zigzag NWs and novel structures for broad applications.

Differential roles of two delayed rectifier potassium currents in regulation of ventricular action potential duration and arrhythmia susceptibility.

PubMed

Devenyi, Ryan A; Ortega, Francis A; Groenendaal, Willemijn; Krogh-Madsen, Trine; Christini, David J; Sobie, Eric A

2017-04-01

Arrhythmias result from disruptions to cardiac electrical activity, although the factors that control cellular action potentials are incompletely understood. We combined mathematical modelling with experiments in heart cells from guinea pigs to determine how cellular electrical activity is regulated. A mismatch between modelling predictions and the experimental results allowed us to construct an improved, more predictive mathematical model. The balance between two particular potassium currents dictates how heart cells respond to perturbations and their susceptibility to arrhythmias. Imbalances of ionic currents can destabilize the cardiac action potential and potentially trigger lethal cardiac arrhythmias. In the present study, we combined mathematical modelling with information-rich dynamic clamp experiments to determine the regulation of action potential morphology in guinea pig ventricular myocytes. Parameter sensitivity analysis was used to predict how changes in ionic currents alter action potential duration, and these were tested experimentally using dynamic clamp, a technique that allows for multiple perturbations to be tested in each cell. Surprisingly, we found that a leading mathematical model, developed with traditional approaches, systematically underestimated experimental responses to dynamic clamp perturbations. We then re-parameterized the model using a genetic algorithm, which allowed us to estimate ionic current levels in each of the cells studied. This unbiased model adjustment consistently predicted an increase in the rapid delayed rectifier K + current and a drastic decrease in the slow delayed rectifier K + current, and this prediction was validated experimentally. Subsequent simulations with the adjusted model generated the clinically relevant prediction that the slow delayed rectifier is better able to stabilize the action potential and suppress pro-arrhythmic events than the rapid delayed rectifier. In summary, iterative coupling of

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

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

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

Influence of cavitation bubble growth by rectified diffusion on cavitation-enhanced HIFU

NASA Astrophysics Data System (ADS)

Okita, Kohei; Sugiyama, Kazuyasu; Takagi, Shu; Matsumoto, Yoichiro

2017-11-01

Cavitation is becoming increasingly important in therapeutic ultrasound applications such as diagnostic, tumor ablation and lithotripsy. Mass transfer through gas-liquid interface due to rectified diffusion is important role in an initial stage of cavitation bubble growth. In the present study, influences of the rectified diffusion on cavitation-enhanced high-intensity focused ultrasound (HIFU) was investigated numerically. Firstly, the mass transfer rate of gas from the surrounding medium to the bubble was examined as function of the initial bubble radius and the driving pressure amplitude. As the result, the pressure required to bubble growth was decreases with increasing the initial bubble radius. Next, the cavitation-enhanced HIFU, which generates cavitation bubbles by high-intensity burst and induces the localized heating owing to cavitation bubble oscillation by low-intensity continuous waves, was reproduced by the present simulation. The heating region obtained by the simulation is agree to the treatment region of an in vitro experiment. Additionally, the simulation result shows that the localized heating is enhanced by the increase of the equilibrium bubble size due to the rectified diffusion. This work was supported by JSPS KAKENHI Grant Numbers JP26420125,JP17K06170.

Rectifying calibration error of Goldmann applanation tonometer is easy!

PubMed

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

2014-11-01

Purpose: Goldmann applanation tonometer (GAT) is the current Gold standard tonometer. However, its calibration error is common and can go unnoticed in clinics. Its company repair has limitations. The purpose of this report is to describe a self-taught technique of rectifying calibration error of GAT. Materials and Methods: Twenty-nine slit-lamp-mounted Haag-Streit Goldmann tonometers (Model AT 900 C/M; Haag-Streit, Switzerland) were included in this cross-sectional interventional pilot study. The technique of rectification of calibration error of the tonometer involved cleaning and lubrication of the instrument followed by alignment of weights when lubrication alone didn't suffice. We followed the South East Asia Glaucoma Interest Group's definition of calibration error tolerance (acceptable GAT calibration error within ±2, ±3 and ±4 mm Hg at the 0, 20 and 60-mm Hg testing levels, respectively). Results: Twelve out of 29 (41.3%) GATs were out of calibration. The range of positive and negative calibration error at the clinically most important 20-mm Hg testing level was 0.5 to 20 mm Hg and -0.5 to -18 mm Hg, respectively. Cleaning and lubrication alone sufficed to rectify calibration error of 11 (91.6%) faulty instruments. Only one (8.3%) faulty GAT required alignment of the counter-weight. Conclusions: Rectification of calibration error of GAT is possible in-house. Cleaning and lubrication of GAT can be carried out even by eye care professionals and may suffice to rectify calibration error in the majority of faulty instruments. Such an exercise may drastically reduce the downtime of the Gold standard tonometer.

Principle and design of small-sized and high-definition x-ray machine

NASA Astrophysics Data System (ADS)

Zhao, Anqing

2010-10-01

The paper discusses the circuit design and working principles of VMOS PWM type 75KV10mA high frequency X-ray machine. The system mainly consists of silicon controlled rectifier, VMOS tube PWM type high-frequency and highvoltage inverter circuit, filament inverter circuit, high-voltage rectifier filter circuit and as X-ray tube. The working process can be carried out under the control of a single-chip microcomputer. Due to the small size and high resolution in imaging, the X-ray machine is mostly adopted for emergent medical diagnosis and specific circumstances where nondestructive tests are conducted.

Rectifying behavior in the GaN/graded-AlxGa1‑xN/GaN double heterojunction structure

NASA Astrophysics Data System (ADS)

Wang, Caiwei; Jiang, Yang; Ma, Ziguang; Zuo, Peng; Yan, Shen; Die, Junhui; Wang, Lu; Jia, Haiqiang; Wang, Wenxin; Chen, Hong

2018-05-01

Rectifying characteristics induced by the polarization fields are achieved in the GaN/graded-AlxGa1‑xN/GaN double heterojunction structure (DHS). By grading AlxGa1‑xN from x  =  0.4(0.3) to 0.1, the DHS displays a better conductivity for smaller reverse bias than for forward bias voltages (reverse rectifying behavior) which is opposite to p–n junction rectifying characteristics. The mechanism of reverse rectifying behavior is illustrated via calculating the energy band structures of the samples. The band gap narrowing caused by decreasing Al composition could compensate the for the band tilt due to the polarization effect in AlxGa1‑xN barriers, thus lowering the barrier height for electron transport from top to bottom. The reverse rectifying behavior could be enhanced by increasing the Al content and the thickness of the multi-layer graded AlxGa1‑xN barriers. This work gives a better understanding of the mechanism of carrier transport in a DHS and makes it possible to realize novel GaN-based heterojunction transistors.

High performance ripple feedback for the buck unity-power-factor rectifier

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

Lo, Y.W.; King, R.J.

1995-03-01

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 frommore » 50% to discontinuous-conduction-mode operation are given.« less

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

PubMed Central

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

2013-01-01

A microfluidic rectifier incorporating an obstructed microchannel and a PDMS membrane is proposed. During forward flow, the membrane deflects in the upward direction; thereby allowing the fluid to pass over the obstacle. Conversely, during reverse flow, the membrane seals against the obstacle, thereby closing the channel and preventing flow. It is shown that the proposed device can operate over a wide pressure range by increasing or decreasing the membrane thickness as required. A microfluidic pump is realized by integrating the rectifier with a simple stepper motor mechanism. The experimental results show that the pump can achieve a vertical left height of more than 2 m. Moreover, it is shown that a maximum flow rate of 6.3 ml/min can be obtained given a membrane thickness of 200 μm and a motor velocity of 80 rpm. In other words, the proposed microfluidic rectifier not only provides an effective means of preventing reverse flow but also permits the realization of a highly efficient microfluidic pump. PMID:24404051

Silicon Carbide MOSFET-Based Switching Power Amplifier for Precision Magnet Control

NASA Astrophysics Data System (ADS)

Miller, Kenneth; Ziemba, Timothy; Prager, James; Picard, Julian

2016-10-01

Eagle Harbor Technologies, Inc. (EHT) is using the latest in solid-state switching technologies to advance the state-of-the-art in magnet control for fusion science. Silicon carbide (SiC) MOSFETs offer advantages over IGBTs including lower drive energy requirements, lower conduction and switching losses, and higher switching frequency capabilities. When comparing SiC and traditional silicon-based MOSFETs, SiC MOSFETs provide higher current carrying capability allowing for smaller package weights and sizes and lower operating temperature. To validate the design, EHT has developed a low-power switching power amplifier (SPA), which has been used for precision control of magnetic fields, including rapidly changing the fields in coils. This design has been incorporated in to a high power SPA, which has been bench tested. This high power SPA will be tested at the Helicity Injected Torus (HIT) at the University of Washington. Following successful testing, EHT will produce enough SiC MOSFET-based SPAs to replace all of the units at HIT, which allows for higher frequency operation and an overall increase in pulsed current levels.

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

NASA Technical Reports Server (NTRS)

Birchenough, A. G.

1971-01-01

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

35 GHz integrated circuit rectifying antenna with 33 percent efficiency

NASA Technical Reports Server (NTRS)

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

1991-01-01

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

Regenerative Snubber For GTO-Commutated SCR Inverter

NASA Technical Reports Server (NTRS)

Rippel, Wally E.; Edwards, Dean B.

1992-01-01

Proposed regenerative snubbing circuit substituted for dissipative snubbing circuit in inverter based on silicon controlled rectifiers (SCR's) commutated by gate-turn-off thyristor (GTO). Intended to reduce loss of power that occurs in dissipative snubber. Principal criteria in design: low cost, simplicity, and reliability.

An electronic circuit for sensing malfunctions in test instrumentation

NASA Technical Reports Server (NTRS)

Miller, W. M., Jr.

1969-01-01

Monitoring device differentiates between malfunctions occurring in the system undergoing test and malfunctions within the test instrumentation itself. Electronic circuits in the monitor use transistors to commutate silicon controlled rectifiers by removing the drive voltage, display circuits are then used to monitor multiple discrete lines.

Direct block of inward rectifier potassium channels by nicotine.

PubMed

Wang, H; Yang, B; Zhang, L; Xu, D; Wang, Z

2000-04-01

Nicotine has been shown to depolarize membrane potential and to lengthen action potential duration in isolated cardiac preparations. To investigate whether this is a consequence of direct interaction of nicotine with inward rectifier K(+) channels which are a key determinant of membrane potentials, we assessed the effects of nicotine on two cloned human inward rectifier K(+) channels, Kir2.1 and Kir2.2, expressed in Xenopus oocytes and the native inward rectifier K(+) current I(K1) in canine ventricular myocytes. Nicotine suppressed Kir2.1-expressed currents at varying potentials negative to -20 mV, with more pronounced effects on the outward current between -70 and -20 mV relative to the inward current at hyperpolarized potentials (below -70 mV). The inhibition was concentration dependent. For the outward currents recorded at -50 mV, the IC50 was 165 +/- 18 microM. Similar effects of nicotine were observed for Kir2.2. A more potent effect was seen with I(K1) in canine myocytes. Significant blockade ( approximately 60%) was found at a concentration as low as 0.5 microM and the IC50 was 4.0 +/- 0.4 microM. The effects in both oocytes and myocytes were partially reversible upon washout of nicotine. Antagonists of nicotinic receptors (mecamylamine, 100 microM), muscarinic receptors (atropine, 1 microM), and beta-adrenergic receptors (propranolol, 1 microM) all failed to restore the depressed currents, suggesting that nicotine acted directly on Kir channels, independent of catecholamine release. This property of nicotine may explain its membrane-depolarizing and action potential duration-prolonging effects in cardiac cells and may contribute in part to its ability to promote propensity for cardiac arrhythmias. Copyright 2000 Academic Press.

Control of single-electron charging of metallic nanoparticles onto amorphous silicon surface.

PubMed

Weis, Martin; Gmucová, Katarína; Nádazdy, Vojtech; Capek, Ignác; Satka, Alexander; Kopáni, Martin; Cirák, Július; Majková, Eva

2008-11-01

Sequential single-electron charging of iron oxide nanoparticles encapsulated in oleic acid/oleyl amine envelope and deposited by the Langmuir-Blodgett technique onto Pt electrode covered with undoped hydrogenated amorphous silicon film is reported. Single-electron charging (so-called quantized double-layer charging) of nanoparticles is detected by cyclic voltammetry as current peaks and the charging effect can be switched on/off by the electric field in the surface region induced by the excess of negative/positive charged defect states in the amorphous silicon layer. The particular charge states in amorphous silicon are created by the simultaneous application of a suitable bias voltage and illumination before the measurement. The influence of charged states on the electric field in the surface region is evaluated by the finite element method. The single-electron charging is analyzed by the standard quantized double layer model as well as two weak-link junctions model. Both approaches are in accordance with experiment and confirm single-electron charging by tunnelling process at room temperature. This experiment illustrates the possibility of the creation of a voltage-controlled capacitor for nanotechnology.

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

PubMed Central

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

2010-01-01

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

An FPGA-Based Silicon Neuronal Network with Selectable Excitability Silicon Neurons

PubMed Central

Li, Jing; Katori, Yuichi; Kohno, Takashi

2012-01-01

This paper presents a digital silicon neuronal network which simulates the nerve system in creatures and has the ability to execute intelligent tasks, such as associative memory. Two essential elements, the mathematical-structure-based digital spiking silicon neuron (DSSN) and the transmitter release based silicon synapse, allow us to tune the excitability of silicon neurons and are computationally efficient for hardware implementation. We adopt mixed pipeline and parallel structure and shift operations to design a sufficient large and complex network without excessive hardware resource cost. The network with 256 full-connected neurons is built on a Digilent Atlys board equipped with a Xilinx Spartan-6 LX45 FPGA. Besides, a memory control block and USB control block are designed to accomplish the task of data communication between the network and the host PC. This paper also describes the mechanism of associative memory performed in the silicon neuronal network. The network is capable of retrieving stored patterns if the inputs contain enough information of them. The retrieving probability increases with the similarity between the input and the stored pattern increasing. Synchronization of neurons is observed when the successful stored pattern retrieval occurs. PMID:23269911

Direct block of native and cloned (Kir2.1) inward rectifier K+ channels by chloroethylclonidine

PubMed Central

Barrett-Jolley, R; Dart, C; Standen, N B

1999-01-01

We have investigated the inhibition of inwardly rectifying potassium channels by the α-adrenergic agonist/antagonist chloroethylclonidine (CEC). We used two preparations; two-electrode voltage-clamp of rat isolated flexor digitorum brevis muscle and whole-cell patch-clamp of cell lines transfected with Kir2.1 (IRK1).In skeletal muscle and at a membrane potential of −50 mV, chloroethylclonidine (CEC), an agonist at α2-adrenergic receptors and an antagonist at α1x-receptors, was found to inhibit the inward rectifier current with a Ki of 30 μM.The inhibition of skeletal muscle inward rectifier current by CEC was not mimicked by clonidine, adrenaline or noradrenaline and was not sensitive to high concentrations of α1-(prazosin) or α2-(rauwolscine) antagonists.The degree of current inhibition by CEC was found to vary with the membrane potential (approximately 70% block at −50 mV c.f. ∼10% block at −190 mV). The kinetics of this voltage dependence were further investigated using recombinant inward rectifier K+ channels (Kir2.1) expressed in the MEL cell line. Using a two pulse protocol, we calculated the time constant for block to be ∼8 s at 0 mV, and the rate of unblock was described by the relationship τ=exp((Vm+149)/22) s.This block was effective when CEC was applied to either the inside or the outside of patch clamped cells, but ineffective when a polyamine binding site (aspartate 172) was mutated to asparagine.The data suggest that the clonidine-like imidazoline compound, CEC, inhibits inward rectifier K+ channels independently of α-receptors by directly blocking the channel pore, possibly at an intracellular polyamine binding site. PMID:10516659

Kir2.1 encodes the inward rectifier potassium channel in rat arterial smooth muscle cells

PubMed Central

Bradley, Karri K; Jaggar, Jonathan H; Bonev, Adrian D; Heppner, Thomas J; Flynn, Elaine RM; Nelson, Mark T; Horowitz, Burton

1999-01-01

The molecular nature of the strong inward rectifier K+ channel in vascular smooth muscle was explored by using isolated cell RT-PCR, cDNA cloning and expression techniques.RT-PCR of RNA from single smooth muscle cells of rat cerebral (basilar), coronary and mesenteric arteries revealed transcripts for Kir2.1. Transcripts for Kir2.2 and Kir2.3 were not found.Quantitative PCR analysis revealed significant differences in transcript levels of Kir2.1 between the different vascular preparations (n = 3; P < 0.05). A two-fold difference was detected between Kir2.1 mRNA and β-actin mRNA in coronary arteries when compared with relative levels measured in mesenteric and basilar preparations.Kir2.1 was cloned from rat mesenteric vascular smooth muscle cells and expressed in Xenopus oocytes. Currents were strongly inwardly rectifying and selective for K+.The effect of extracellular Ba2+, Ca2+, Mg2+ and Cs2+ ions on cloned Kir2.1 channels expressed in Xenopus oocytes was examined. Ba2+ and Cs+ block were steeply voltage dependent, whereas block by external Ca2+ and Mg2+ exhibited little voltage dependence. The apparent half-block constants and voltage dependences for Ba2+, Cs+, Ca2+ and Mg2+ were very similar for inward rectifier K+ currents from native cells and cloned Kir2.1 channels expressed in oocytes.Molecular studies demonstrate that Kir2.1 is the only member of the Kir2 channel subfamily present in vascular arterial smooth muscle cells. Expression of cloned Kir2.1 in Xenopus oocytes resulted in inward rectifier K+ currents that strongly resemble those that are observed in native vascular arterial smooth muscle cells. We conclude that Kir2.1 encodes for inward rectifier K+ channels in arterial smooth muscle. PMID:10066894

Creating and Controlling Single Spins in Silicon Carbide

NASA Astrophysics Data System (ADS)

Christle, David

Silicon carbide (SiC) is a well-established commercial semiconductor used in high-power electronics, optoelectronics, and nanomechanical devices, and has recently shown promise for semiconductor-based implementations of quantum information technologies. In particular, a set of divacancy-related point defects have improved coherence properties relative to the prominent nitrogen-vacancy center in diamond, are addressable at near-telecom wavelengths, and reside in a material for which there already exist advanced growth, doping, and microfabrication capabilities. These properties suggest divacancies in SiC have compelling advantages for photonics and micromechanical applications, yet their relatively recent discovery means crucial aspects of their fundamental physics for these applications are not well understood. I will review our progress on manipulating spin defects in SiC, and discuss efforts towards isolating and controlling them at the single defect limit. In particular, our most recent experimental results demonstrate isolation and control of long-lived (T2 = 0 . 9 ms) divacancies in a form of SiC that can be grown epitaxially on silicon. By studying the time-resolved photoluminescence of a single divacancy, we reveal its fundamental orbital structure and characterize in detail the dynamics of its special optical cycle. Finally, we probe individual divacancies using resonant laser techniques and reveal an efficient spin-photon interface with figures of merit comparable to those reported for NV centers in diamond. These results suggest a pathway towards photon-mediated entanglement of SiC defect spins over long distances. This work was supported by NSF, AFOSR, the Argonne CNM, the Knut & Alice Wallenberg Foundation, the Linköping Linnaeus Initiative, the Swedish Government Strategic Research Area, and the Ministry of Education, Science, Sports and Culture of Japan.

Modulation Doping of Silicon using Aluminium-induced Acceptor States in Silicon Dioxide

PubMed Central

König, Dirk; Hiller, Daniel; Gutsch, Sebastian; Zacharias, Margit; Smith, Sean

2017-01-01

All electronic, optoelectronic or photovoltaic applications of silicon depend on controlling majority charge carriers via doping with impurity atoms. Nanoscale silicon is omnipresent in fundamental research (quantum dots, nanowires) but also approached in future technology nodes of the microelectronics industry. In general, silicon nanovolumes, irrespective of their intended purpose, suffer from effects that impede conventional doping due to fundamental physical principles such as out-diffusion, statistics of small numbers, quantum- or dielectric confinement. In analogy to the concept of modulation doping, originally invented for III-V semiconductors, we demonstrate a heterostructure modulation doping method for silicon. Our approach utilizes a specific acceptor state of aluminium atoms in silicon dioxide to generate holes as majority carriers in adjacent silicon. By relocating the dopants from silicon to silicon dioxide, Si nanoscale doping problems are circumvented. In addition, the concept of aluminium-induced acceptor states for passivating hole selective tunnelling contacts as required for high-efficiency photovoltaics is presented and corroborated by first carrier lifetime and tunnelling current measurements. PMID:28425460

Commutating Permanent-Magnet Motors At Low Speed

NASA Technical Reports Server (NTRS)

Dolland, C.

1985-01-01

Circuit provides forced commutation during starting. Forced commutation circuit diverts current from inverter SCR's and turns SCR's off during commutation intervals. Silicon controlled rectifier in circuit unnecessary when switch S10 replaced by high-current, high-voltage transistor. At present, high-current, low-voltage device must suffice.

Simple circuit monitors "third wire" in ac lines

NASA Technical Reports Server (NTRS)

Kojima, T. T.; Stuck, D. E.

1980-01-01

Device detects interruption of ground connection in three-wire electrical equipment and shuts off ac power to prevent shock hazard. Silicon-controlled rectifiers detect floating ground, and deenergize optoelectric relays thereby breaking power connections. Circuit could be incorporated into hand tools, appliances, and other electrical equipment.

Control of carbon balance in a silicon smelting furnace

DOEpatents

Dosaj, Vishu D.; Haines, Cathryn M.; May, James B.; Oleson, John D.

1992-12-29

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

Adjustable Lid Aids Silicon-Ribbon Growth

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

Control of the Pore Texture in Nanoporous Silicon via Chemical Dissolution.

PubMed

Secret, Emilie; Wu, Chia-Chen; Chaix, Arnaud; Galarneau, Anne; Gonzalez, Philippe; Cot, Didier; Sailor, Michael J; Jestin, Jacques; Zanotti, Jean-Marc; Cunin, Frédérique; Coasne, Benoit

2015-07-28

The surface and textural properties of porous silicon (pSi) control many of its physical properties essential to its performance in key applications such as optoelectronics, energy storage, luminescence, sensing, and drug delivery. Here, we combine experimental and theoretical tools to demonstrate that the surface roughness at the nanometer scale of pSi can be tuned in a controlled fashion using partial thermal oxidation followed by removal of the resulting silicon oxide layer with hydrofluoric acid (HF) solution. Such a process is shown to smooth the pSi surface by means of nitrogen adsorption, electron microscopy, and small-angle X-ray and neutron scattering. Statistical mechanics Monte Carlo simulations, which are consistent with the experimental data, support the interpretation that the pore surface is initially rough and that the oxidation/oxide removal procedure diminishes the surface roughness while increasing the pore diameter. As a specific example considered in this work, the initial roughness ξ ∼ 3.2 nm of pSi pores having a diameter of 7.6 nm can be decreased to 1.0 nm following the simple procedure above. This study allows envisioning the design of pSi samples with optimal surface properties toward a specific process.

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

PubMed

Lewohl, J M; Wilson, W R; Mayfield, R D; Brozowski, S J; Morrisett, R A; Harris, R A

1999-12-01

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 oocytes expressing homomeric or heteromeric channels. Function of all GIRK channels was enhanced by intoxicating concentrations of ethanol, but other, related inwardly rectifying potassium channels were not affected. GIRK2/IRK1 chimeras and GIRK2 truncation mutants were used to identify a region of 43 amino acids in the carboxyl (C) terminus that is critical for the action of ethanol on these channels.

Silicon Qubits

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

Ladd, Thaddeus D.; Carroll, Malcolm S.

2018-02-28

Silicon is a promising material candidate for qubits due to the combination of worldwide infrastructure in silicon microelectronics fabrication and the capability to drastically reduce decohering noise channels via chemical purification and isotopic enhancement. However, a variety of challenges in fabrication, control, and measurement leaves unclear the best strategy for fully realizing this material’s future potential. In this article, we survey three basic qubit types: those based on substitutional donors, on metal-oxide-semiconductor (MOS) structures, and on Si/SiGe heterostructures. We also discuss the multiple schema used to define and control Si qubits, which may exploit the manipulation and detection of amore » single electron charge, the state of a single electron spin, or the collective states of multiple spins. Far from being comprehensive, this article provides a brief orientation to the rapidly evolving field of silicon qubit technology and is intended as an approachable entry point for a researcher new to this field.« less

Engineering functionalized multi-phased silicon/silicon oxide nano-biomaterials to passivate the aggressive proliferation of cancer

PubMed Central

Premnath, P.; Tan, B.; Venkatakrishnan, K.

2015-01-01

Currently, the use of nano silicon in cancer therapy is limited as drug delivery vehicles and markers in imaging, not as manipulative/controlling agents. This is due to limited properties that native states of nano silicon and silicon oxides offers. We introduce nano-functionalized multi-phased silicon/silicon oxide biomaterials synthesized via ultrashort pulsed laser synthesis, with tunable properties that possess inherent cancer controlling properties that can passivate the progression of cancer. This nanostructured biomaterial is composed of individual functionalized nanoparticles made of a homogenous hybrid of multiple phases of silicon and silicon oxide in increasing concentration outwards from the core. The chemical properties of the proposed nanostructure such as number of phases, composition of phases and crystal orientation of each functionalized nanoparticle in the three dimensional nanostructure is defined based on precisely tuned ultrashort pulsed laser-material interaction mechanisms. The amorphous rich phased biomaterial shows a 30 fold (95%) reduction in number of cancer cells compared to bulk silicon in 48 hours. Further, the size of the cancer cells reduces by 76% from 24 to 48 hours. This method exposes untapped properties of combination of multiple phases of silicon oxides and its applications in cancer therapy. PMID:26190009

Effect of positive pulse charge waveforms on cycle life of nickel-zinc cells

NASA Technical Reports Server (NTRS)

Smithrick, J. J.

1979-01-01

Five amp-hour nickel-zinc cells were life cycled to evaluate four different charge methods. Three of the four waveforms investigated were 120 Hz full wave rectified sinusoidal (FWRS), 120 Hz silicon controlled rectified (SCR), and 1 kHz square wave (SW). The fourth, a constant current method, was used as a baseline of comparison. Three sealed Ni-Zn cells connected in series were cycled. Each series string was charged at an average c/20 rate, and discharged at a c/2.5 rate to a 75% rated depth.

Inward rectifier potassium currents in mammalian skeletal muscle fibres

PubMed Central

DiFranco, Marino; Yu, Carl; Quiñonez, Marbella; Vergara, Julio L

2015-01-01

Inward rectifying potassium (Kir) channels play a central role in maintaining the resting membrane potential of skeletal muscle fibres. Nevertheless their role has been poorly studied in mammalian muscles. Immunohistochemical and transgenic expression were used to assess the molecular identity and subcellular localization of Kir channel isoforms. We found that Kir2.1 and Kir2.2 channels were targeted to both the surface andthe transverse tubular system membrane (TTS) compartments and that both isoforms can be overexpressed up to 3-fold 2 weeks after transfection. Inward rectifying currents (IKir) had the canonical features of quasi-instantaneous activation, strong inward rectification, depended on the external [K+], and could be blocked by Ba2+ or Rb+. In addition, IKir records show notable decays during large 100 ms hyperpolarizing pulses. Most of these properties were recapitulated by model simulations of the electrical properties of the muscle fibre as long as Kir channels were assumed to be present in the TTS. The model also simultaneously predicted the characteristics of membrane potential changes of the TTS, as reported optically by a fluorescent potentiometric dye. The activation of IKir by large hyperpolarizations resulted in significant attenuation of the optical signals with respect to the expectation for equal magnitude depolarizations; blocking IKir with Ba2+ (or Rb+) eliminated this attenuation. The experimental data, including the kinetic properties of IKir and TTS voltage records, and the voltage dependence of peak IKir, while measured at widely dissimilar bulk [K+] (96 and 24 mm), were closely predicted by assuming Kir permeability (PKir) values of ∼5.5 × 10−6 cm s−1 and equal distribution of Kir channels at the surface and TTS membranes. The decay of IKir records and the simultaneous increase in TTS voltage changes were mostly explained by K+ depletion from the TTS lumen. Most importantly, aside from allowing an accurate estimation of

Polypropylene vs silicone Ahmed valve with adjunctive mitomycin C in paediatric age group: a prospective controlled study

PubMed Central

El Sayed, Y; Awadein, A

2013-01-01

Purpose To compare the results of silicone and polypropylene Ahmed glaucoma valves (AGV) implanted during the first 10 years of life. Methods A prospective study was performed on 50 eyes of 33 patients with paediatric glaucoma. Eyes were matched to either polypropylene or silicone AGV. In eyes with bilateral glaucoma, one eye was implanted with polypropylene and the other eye was implanted with silicone AGV. Results Fifty eyes of 33 children were reviewed. Twenty five eyes received a polypropylene valve, and 25 eyes received a silicone valve. Eyes implanted with silicone valves achieved a significantly lower intraocular pressure (IOP) compared with the polypropylene group at 6 months, 1 year, and 2 years postoperatively. The average survival time was significantly longer (P=0.001 by the log-rank test) for the silicone group than for the polypropylene group and the cumulative probability of survival by the log-rank test at the end of the second year was 80% (SE: 8.0, 95% confidence interval (CI): 64–96%) in the silicone group and 56% (SE: 9.8, 95% CI: 40–90%) in the polypropylene group. The difference in the number of postoperative interventions and complications between both groups was statistically insignificant. Conclusion Silicone AGVs can achieve better IOP control, and longer survival with less antiglaucoma drops compared with polypropylene valves in children younger than 10 years. PMID:23579403

Accurate control of oxygen level in cells during culture on silicone rubber membranes with application to stem cell differentiation.

PubMed

Powers, Daryl E; Millman, Jeffrey R; Bonner-Weir, Susan; Rappel, Michael J; Colton, Clark K

2010-01-01

Oxygen level in mammalian cell culture is often controlled by placing culture vessels in humidified incubators with a defined gas phase partial pressure of oxygen (pO(2gas)). Because the cells are consuming oxygen supplied by diffusion, a difference between pO(2gas) and that experienced by the cells (pO(2cell)) arises, which is maximal when cells are cultured in vessels with little or no oxygen permeability. Here, we demonstrate theoretically that highly oxygen-permeable silicone rubber membranes can be used to control pO(2cell) during culture of cells in monolayers and aggregates much more accurately and can achieve more rapid transient response following a disturbance than on polystyrene and fluorinated ethylene-propylene copolymer membranes. Cell attachment on silicone rubber was achieved by physical adsorption of fibronectin or Matrigel. We use these membranes for the differentiation of mouse embryonic stem cells to cardiomyocytes and compare the results with culture on polystyrene or on silicone rubber on top of polystyrene. The fraction of cells that are cardiomyocyte-like increases with decreasing pO(2) only when using oxygen-permeable silicone membrane-based dishs, which contract on silicone rubber but not polystyrene. The high permeability of silicone rubber results in pO(2cell) being equal to pO(2gas) at the tissue-membrane interface. This, together with geometric information from histological sections, facilitates development of a model from which the pO(2) distribution within the resulting aggregates is computed. Silicone rubber membranes have significant advantages over polystyrene in controlling pO(2cell), and these results suggest they are a valuable tool for investigating pO(2) effects in many applications, such as stem cell differentiation. Copyright 2009 American Institute of Chemical Engineers

Development of high temperature gallium phosphide rectifiers

NASA Technical Reports Server (NTRS)

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

1972-01-01

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

LabVIEW-based control and acquisition system for the dosimetric characterization of a silicon strip detector.

PubMed

Ovejero, M C; Pérez Vega-Leal, A; Gallardo, M I; Espino, J M; Selva, A; Cortés-Giraldo, M A; Arráns, R

2017-02-01

The aim of this work is to present a new data acquisition, control, and analysis software system written in LabVIEW. This system has been designed to obtain the dosimetry of a silicon strip detector in polyethylene. It allows the full automation of the experiments and data analysis required for the dosimetric characterization of silicon detectors. It becomes a useful tool that can be applied in the daily routine check of a beam accelerator.

Field-effect transistors as electrically controllable nonlinear rectifiers for the characterization of terahertz pulses

NASA Astrophysics Data System (ADS)

Lisauskas, Alvydas; Ikamas, Kestutis; Massabeau, Sylvain; Bauer, Maris; ČibiraitÄ--, DovilÄ--; Matukas, Jonas; Mangeney, Juliette; Mittendorff, Martin; Winnerl, Stephan; Krozer, Viktor; Roskos, Hartmut G.

2018-05-01

We propose to exploit rectification in field-effect transistors as an electrically controllable higher-order nonlinear phenomenon for the convenient monitoring of the temporal characteristics of THz pulses, for example, by autocorrelation measurements. This option arises because of the existence of a gate-bias-controlled super-linear response at sub-threshold operation conditions when the devices are subjected to THz radiation. We present measurements for different antenna-coupled transistor-based THz detectors (TeraFETs) employing (i) AlGaN/GaN high-electron-mobility and (ii) silicon CMOS field-effect transistors and show that the super-linear behavior in the sub-threshold bias regime is a universal phenomenon to be expected if the amplitude of the high-frequency voltage oscillations exceeds the thermal voltage. The effect is also employed as a tool for the direct determination of the speed of the intrinsic TeraFET response which allows us to avoid limitations set by the read-out circuitry. In particular, we show that the build-up time of the intrinsic rectification signal of a patch-antenna-coupled CMOS detector changes from 20 ps in the deep sub-threshold voltage regime to below 12 ps in the vicinity of the threshold voltage.

[Research progress in the role of aquaproin-4 and inward rectifying potassium channel 4.1 in spinal cord edema].

PubMed

Chen, Tiege; Dang, Yuexiu; Wang, Ming; Zhang, Dongliang; Guo, Yongqiang; Zhang, Haihong

2018-05-28

Spinal edema is a very important pathophysiological basis for secondary spinal cord injury, which affects the repair and prognosis of spinal cord injury. Aquaporin-4 is widely distributed in various organs of the body, and is highly expressed in the brain and spinal cord. Inward rectifying potassium channel 4.1 is a protein found in astrocytes of central nervous system. It interacts with aquaporins in function. Aquaporin-4 and inward rectifying potassium channel 4.1 play an important role in the formation and elimination of spinal cord edema, inhibition of glial scar formation and promotion of excitotoxic agents exclusion. The distribution and function of aquaporin-4 and inward rectifying potassium channel 4.1 in the central nervous system and their expression after spinal cord injury have multiple effects on spinal edema. Studies of aquaporin-4 and inward rectifying potassium channel 4.1 in the spinal cord may provide new ideas for the elimination and treatment of spinal edema.

Pressure garment therapy alone and in combination with silicone for the prevention of hypertrophic scarring: randomized controlled trial with intraindividual comparison.

PubMed

Steinstraesser, Lars; Flak, Ewa; Witte, Bernd; Ring, Andrej; Tilkorn, Daniel; Hauser, Jörg; Langer, Stefan; Steinau, Hans-Ulrich; Al-Benna, Sammy

2011-10-01

Published trials evaluating pressure garment and/or silicone therapy as a treatment for hypertrophic burn scarring are of poor quality and highly susceptible to bias. The authors' aim was to compare the efficacy of pressure garment therapy alone and in combination with silicone gel sheet or spray therapy for the prevention of hypertrophic scarring. The authors conducted an open, single-center, randomized controlled study with intraindividual comparison of study preparations and control to standard treatment. Forty-three consecutive patients with two comparable areas of split-thickness graft burn wounds were recruited into the study, and 38 patients were followed up for 18 months. All patients received compression garments and were randomized to one of two treatment groups: (1) self-drying silicone spray and compression versus compression alone and (2) silicone sheeting and compression versus compression alone. Clinical assessment, measurement of scar redness, height, and photographic documentation of each treated area were performed at different visits over an 18-month follow-up period. Significance was tested using repeated-measures analyses and Wilcoxon paired-sample signed rank tests. Use of pressure garment therapy alone produced results equivalent to those of combined silicone and pressure garment therapy in the prevention of hypertrophic scars. The efficacy of silicone spray therapy was comparable to that of silicone gel sheet therapy in the prevention of hypertrophic scars. Patients treated with silicone spray had fewer side effects when compared with the silicone sheet group. Multimodal therapy with silicone and pressure garment therapy failed to prevent hypertrophic scars beyond that observed with pressure garment therapy alone. Therapeutic, II.

Self-contained sub-millimeter wave rectifying antenna integrated circuit

NASA Technical Reports Server (NTRS)

Siegel, Peter H. (Inventor)

2004-01-01

The invention is embodied in a monolithic semiconductor integrated circuit in which is formed an antenna, such as a slot dipole antenna, connected across a rectifying diode. In the preferred embodiment, the antenna is tuned to received an electromagnetic wave of about 2500 GHz so that the device is on the order of a wavelength in size, or about 200 microns across and 30 microns thick. This size is ideal for mounting on a microdevice such as a microrobot for example. The antenna is endowed with high gain in the direction of the incident radiation by providing a quarter-wavelength (30 microns) thick resonant cavity below the antenna, the cavity being formed as part of the monolithic integrated circuit. Preferably, the integrated circuit consists of a thin gallium arsenide membrane overlying the resonant cavity and supporting an epitaxial Gallium Arsenide semiconductor layer. The rectifying diode is a Schottky diode formed in the GaAs semiconductor layer and having an area that is a very small fraction of the wavelength of the 2500 GHz incident radiation. The cavity provides high forward gain in the antenna and isolation from surrounding structure.

Preventing Freezeup in Silicon Ribbon Growth

NASA Technical Reports Server (NTRS)

Mackintosh, B.

1983-01-01

Carefully-shaped heat conductor helps control thermal gradients crucial to growth of single-crystal silicon sheets for solar cells. Ends of die through which silicon sheet is drawn as ribbon from molten silicon. Profiled heat extractor prevents ribbon ends from solidifying prematurely and breaking.

Structurally controlled deposition of silicon onto nanowires

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

Wang, Weijie; Liu, Zuqin; Han, Song

Provided herein are nanostructures for lithium ion battery electrodes and methods of fabrication. In some embodiments, a nanostructure template coated with a silicon coating is provided. The silicon coating may include a non-conformal, more porous layer and a conformal, denser layer on the non-conformal, more porous layer. In some embodiments, two different deposition processes, e.g., a PECVD layer to deposit the non-conformal layer and a thermal CVD process to deposit the conformal layer, are used. Anodes including the nanostructures have longer cycle lifetimes than anodes made using either a PECVD or thermal CVD method alone.

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

Development of 24GHz Rectenna for Receiving and Rectifying Modulated Waves

NASA Astrophysics Data System (ADS)

Shinohara, Naoki; Hatano, Ken

2014-11-01

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

Competitive inhibition can linearize dose-response and generate a linear rectifier

PubMed Central

Savir, Yonatan; Tu, Benjamin P.; Springer, Michael

2015-01-01

Summary Many biological responses require a dynamic range that is larger than standard bi-molecular interactions allow, yet the also ability to remain off at low input. Here we mathematically show that an enzyme reaction system involving a combination of competitive inhibition, conservation of the total level of substrate and inhibitor, and positive feedback can behave like a linear rectifier—that is, a network motif with an input-output relationship that is linearly sensitive to substrate above a threshold but unresponsive below the threshold. We propose that the evolutionarily conserved yeast SAGA histone acetylation complex may possess the proper physiological response characteristics and molecular interactions needed to perform as a linear rectifier, and we suggest potential experiments to test this hypothesis. One implication of this work is that linear responses and linear rectifiers might be easier to evolve or synthetically construct than is currently appreciated. PMID:26495436

Flutter Generator Control and Force Computer.

DTIC Science & Technology

1985-07-01

exciter module 2. Mechanical load 3. Rectifier and triac 4. Overall system 5. Velocity control 6. Microprocessor 7. Operation in 1 ’g’ environment 8...amplifier Output voltage from the rectifier/ triac circuit (figure 3) is a function of the conduction angle of each triac . In a 400 Hz 3-phase system...3IIGCICI FIRING CIRCUIT FIRING CIRCUIT TO MOTOR Figure 3. Rectifier and triac _____ -=low AEL-0242-TNI Figure 4 DEMAND(V V49 -9 APIFE M O T OR

Decreased inward rectifier potassium current IK1 in dystrophin-deficient ventricular cardiomyocytes.

PubMed

Rubi, Lena; Koenig, Xaver; Kubista, Helmut; Todt, Hannes; Hilber, Karlheinz

2017-03-04

Kir2.x channels in ventricular cardiomyocytes (most prominently Kir2.1) account for the inward rectifier potassium current I K1 , which controls the resting membrane potential and the final phase of action potential repolarization. Recently it was hypothesized that the dystrophin-associated protein complex (DAPC) is important in the regulation of Kir2.x channels. To test this hypothesis, we investigated potential I K1 abnormalities in dystrophin-deficient ventricular cardiomyocytes derived from the hearts of Duchenne muscular dystrophy mouse models. We found that I K1 was substantially diminished in dystrophin-deficient cardiomyocytes when compared to wild type myocytes. This finding represents the first functional evidence for a significant role of the DAPC in the regulation of Kir2.x channels.

Candidate locations for SPS rectifying antennas

NASA Technical Reports Server (NTRS)

Eberhardt, A. W.

1977-01-01

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

Baseline tests of the AM General DJ-5E electruck electric delivery van

NASA Technical Reports Server (NTRS)

Dustin, M. O.; Tryon, H. B.; Sargent, N. B.

1977-01-01

An electric quarter ton truck designed for use as a postal delivery vehicle was tested to characterize the state of the art of electric vehicles. Vehicle performance test results are presented. It is powered by a single-module, 54 volt industrial battery through a silicon controlled rectifier continuously adjustable controller with regenerative braking applied to a direct current compound wound motor.

Atomic-Scale Control of Silicon Expansion Space as Ultrastable Battery Anodes.

PubMed

Zhu, Jian; Wang, Tao; Fan, Fengru; Mei, Lin; Lu, Bingan

2016-09-27

Development of electrode materials with high capability and long cycle life are central issues for lithium-ion batteries (LIBs). Here, we report an architecture of three-dimensional (3D) flexible silicon and graphene/carbon nanofibers (FSiGCNFs) with atomic-scale control of the expansion space as the binder-free anode for flexible LIBs. The FSiGCNFs with Si nanoparticles surrounded by accurate and controllable void spaces ensure excellent mechanical strength and afford sufficient space to overcome the damage caused by the volume expansion of Si nanoparticles during charge and discharge processes. This 3D porous structure possessing built-in void space between the Si and graphene/carbon matrix not only limits most solid-electrolyte interphase formation to the outer surface, instead of on the surface of individual NPs, and increases its stability but also achieves highly efficient channels for the fast transport of both electrons and lithium ions during cycling, thus offering outstanding electrochemical performance (2002 mAh g(-1) at a current density of 700 mA g(-1) over 1050 cycles corresponding to 3840 mAh g(-1) for silicon alone and 582 mAh g(-1) at the highest current density of 28 000 mA g(-1)).

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

PubMed Central

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

2011-01-01

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 μm∕s was obtained for 8 μm polystyrene beads, without any electrolysis, using a symmetrical square waveform driving electric field of 5 V∕mm at 10 Hz and a 360 V gate potential with its polarity synchronized with the driving potential (phase lag=0°). PMID:21522497

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

PubMed

Kabra, Vinay; Aamir, Lubna; Malik, M M

2014-01-01

A low cost, highly rectifying, nano heterojunction (p-ZnO/n-Si) diode was fabricated using solution-processed, p-type, ZnO nanoparticles and an n-type Si substrate. p-type ZnO nanoparticles were synthesized using a chemical synthesis route and characterized by XRD and a Hall effect measurement system. The device was fabricated by forming thin film of synthesized p-ZnO nanoparticles on an n-Si substrate using a dip coating technique. The device was then characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The effect of UV illumination on the I-V characteristics was also explored and indicated the formation of a highly rectifying, nano heterojunction with a rectification ratio of 101 at 3 V, which increased nearly 2.5 times (232 at 3 V) under UV illumination. However, the cut-in voltage decreases from 1.5 V to 0.9 V under UV illumination. The fabricated device could be used in switches, rectifiers, clipper and clamper circuits, BJTs, MOSFETs and other electronic circuitry.

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

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

Mark A. Johnson

2012-06-29

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.

Silicon Micromachined Microlens Array for THz Antennas

NASA Technical Reports Server (NTRS)

Lee, Choonsup; Chattopadhyay, Goutam; Mehdi, IImran; Gill, John J.; Jung-Kubiak, Cecile D.; Llombart, Nuria

2013-01-01

5 5 silicon microlens array was developed using a silicon micromachining technique for a silicon-based THz antenna array. The feature of the silicon micromachining technique enables one to microfabricate an unlimited number of microlens arrays at one time with good uniformity on a silicon wafer. This technique will resolve one of the key issues in building a THz camera, which is to integrate antennas in a detector array. The conventional approach of building single-pixel receivers and stacking them to form a multi-pixel receiver is not suited at THz because a single-pixel receiver already has difficulty fitting into mass, volume, and power budgets, especially in space applications. In this proposed technique, one has controllability on both diameter and curvature of a silicon microlens. First of all, the diameter of microlens depends on how thick photoresist one could coat and pattern. So far, the diameter of a 6- mm photoresist microlens with 400 m in height has been successfully microfabricated. Based on current researchers experiences, a diameter larger than 1-cm photoresist microlens array would be feasible. In order to control the curvature of the microlens, the following process variables could be used: 1. Amount of photoresist: It determines the curvature of the photoresist microlens. Since the photoresist lens is transferred onto the silicon substrate, it will directly control the curvature of the silicon microlens. 2. Etching selectivity between photoresist and silicon: The photoresist microlens is formed by thermal reflow. In order to transfer the exact photoresist curvature onto silicon, there needs to be etching selectivity of 1:1 between silicon and photoresist. However, by varying the etching selectivity, one could control the curvature of the silicon microlens. The figure shows the microfabricated silicon microlens 5 x5 array. The diameter of the microlens located in the center is about 2.5 mm. The measured 3-D profile of the microlens surface has a

Periodically poled silicon

NASA Astrophysics Data System (ADS)

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

2010-02-01

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

No efficacy for silicone gel sheeting in prevention of abnormal scar formation in children with cancer: a randomized controlled trial.

PubMed

Braam, Katja I; Kooijmans, Esmee C M; van Dulmen-den Broeder, Eline; Veening, Margreet A; Schouten-van Meeteren, Antoinette Y N; Verhaegen, Pauline D H M; Kaspers, Gertjan J L; Niessen, Frank B; Heij, Hugo A

2015-04-01

Placement of a totally implantable venous access device in children with cancer often leads to hypertrophic scars after its removal. This study investigates whether the use of silicone gel sheets has a beneficial effect on scar outcome in children with cancer. In a three-arm randomized controlled trial, the effects of use of silicone gel sheets for 2 and 6 months were assessed and compared with no intervention in children with cancer after removal of the totally implantable venous access device. Silicone gel sheets were first administered 14 days after surgery. The 1-year follow-up included measurements at seven time points. Next to scar size assessment, the modified Vancouver Scar Scale was used to assess scar outcome. Thirty-six children participated. For hypertrophy, no significant differences were found between the two intervention groups and the control group. However, at 1-year follow-up, the 2-month application group showed significantly smaller scars compared with the group receiving silicone gel sheet treatment for 6 months (p = 0.04), but not when compared with the control group (p = 0.22). Longitudinal multilevel analyses could not confirm these findings and showed no significant intervention effects on both outcomes. This study provides no strong evidence to support the use of silicone gel sheets after totally implantable venous access device removal in children with cancer. There seems to be a small benefit for scar width with application for 2 months. However, for hypertrophy, the scar outcome shows no significant difference between the control group and the 2-month and 6-month treatment groups.

Static analysis of rectifier cabinet for nuclear power generating stations based on finite element method

NASA Astrophysics Data System (ADS)

Yin, Qiang; Chen, Tian-jin; Li, Wei-yang; Xiong, Ze-cheng; Ma, Rui

2017-09-01

In order to obtain the deformation map and equivalent stress distribution of rectifier cabinet for nuclear power generating stations, the quality distribution of structure and electrical are described, the tensile bond strengths of the rings are checked, and the finite element model of cabinet is set up by ANSYS. The transport conditions of the hoisting state and fork loading state are analyzed. The deformation map and equivalent stress distribution are obtained. The attentive problems are put forward. It is a reference for analysis method and the obtained results for the transport of rectifier cabinet for nuclear power generating stations.

Stability and rheology of dispersions of silicon nitride and silicon carbide

NASA Technical Reports Server (NTRS)

Feke, Donald L.

1987-01-01

The relationship between the surface and colloid chemistry of commercial ultra-fine silicon carbide and silicon nitride powders was examined by a variety of standard characterization techniques and by methodologies especially developed for ceramic dispersions. These include electrokinetic measurement, surface titration, and surface spectroscopies. The effects of powder pretreatment and modification strategies, which can be utilized to augment control of processing characteristics, were monitored with these technologies. Both silicon carbide and nitride were found to exhibit silica-like surface chemistries, but silicon nitride powders possess an additional amine surface functionality. Colloidal characteristics of the various nitride powders in aqueous suspension is believed to be highly dependent on the relative amounts of the two types of surface groups, which in turn is determined by the powder synthesis route. The differences in the apparent colloidal characteristics for silicon nitride powders cannot be attributed to the specific absorption of ammonium ions. Development of a model for the prediction of double-layer characteristics of materials with a hybrid site interface facilitated understanding and prediction of the behavior of both surface charge and surface potential for these materials. The utility of the model in application to silicon nitride powders was demonstrated.

Optical force rectifiers based on PT-symmetric metasurfaces

NASA Astrophysics Data System (ADS)

Alaee, Rasoul; Gurlek, Burak; Christensen, Johan; Kadic, Muamer

2018-05-01

We introduce here the concept of optical force rectifier based on parity-time symmetric metasurfaces. Directly linked to the properties of non-Hermitian systems engineered by balanced loss and gain constituents, we show that light can exert asymmetric pulling or pushing forces on metasurfaces depending on the direction of the impinging light. This generates a complete force rectification in the vicinity of the exceptional point. Our findings have the potential to spark the design of applications in optical manipulation where the forces, strictly speaking, act unidirectionally.

Comparison of cloned Kir2 channels with native inward rectifier K+ channels from guinea-pig cardiomyocytes

PubMed Central

Xin Liu, Gong; Derst, Christian; Schlichthörl, Günter; Heinen, Steffen; Seebohm, Guiscard; Brüggemann, Andrea; Kummer, Wolfgang; Veh, Rüdiger W; Daut, Jürgen; Preisig-Müller, Regina

2001-01-01

The aim of the study was to compare the properties of cloned Kir2 channels with the properties of native rectifier channels in guinea-pig (gp) cardiac muscle. The cDNAs of gpKir2.1, gpKir2.2, gpKir2.3 and gpKir2.4 were obtained by screening a cDNA library from guinea-pig cardiac ventricle. A partial genomic structure of all gpKir2 genes was deduced by comparison of the cDNAs with the nucleotide sequences derived from a guinea-pig genomic library. The cell-specific expression of Kir2 channel subunits was studied in isolated cardiomyocytes using a multi-cell RT-PCR approach. It was found that gpKir2.1, gpKir2.2 and gpKir2.3, but not gpKir2.4, are expressed in cardiomyocytes. Immunocytochemical analysis with polyclonal antibodies showed that expression of Kir2.4 is restricted to neuronal cells in the heart. After transfection in human embryonic kidney cells (HEK293) the mean single-channel conductance with symmetrical K+ was found to be 30.6 pS for gpKir2.1, 40.0 pS for gpKir2.2 and 14.2 pS for Kir2.3. Cell-attached measurements in isolated guinea-pig cardiomyocytes (n = 351) revealed three populations of inwardly rectifying K+ channels with mean conductances of 34.0, 23.8 and 10.7 pS. Expression of the gpKir2 subunits in Xenopus oocytes showed inwardly rectifying currents. The Ba2+ concentrations required for half-maximum block at -100 mV were 3.24 μm for gpKir2.1, 0.51 μm for gpKir2.2, 10.26 μm for gpKir2.3 and 235 μm for gpKir2.4. Ba2+ block of inward rectifier channels of cardiomyocytes was studied in cell-attached recordings. The concentration and voltage dependence of Ba2+ block of the large-conductance inward rectifier channels was virtually identical to that of gpKir2.2 expressed in Xenopus oocytes. Our results suggest that the large-conductance inward rectifier channels found in guinea-pig cardiomyocytes (34.0 pS) correspond to gpKir2.2. The intermediate-conductance (23.8 pS) and low-conductance (10.7 pS) channels described here may correspond to gpKir2

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

NASA Astrophysics Data System (ADS)

Long, Yun; Wang, Jian

2014-06-01

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

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

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

NASA Technical Reports Server (NTRS)

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

1986-01-01

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

High-temperature, gas-filled ceramic rectifiers, thyratrons, and voltage-reference tubes

NASA Technical Reports Server (NTRS)

Baum, E. A.

1969-01-01

Thyratron, capable of being operated as a rectifier and a voltage-reference tube, was constructed and tested for 1000 hours at temperatures to 800 degrees C. With current levels at 15 amps and peak voltages of 2000 volts and frequencies at 6000 cps, tube efficiency was greater than 97 percent.

New Control Over Silicone Synthesis using SiH Chemistry: The Piers-Rubinsztajn Reaction.

PubMed

Brook, Michael A

2018-06-18

There is a strong imperative to synthesize polymers with highly controlled structures and narrow property ranges. Silicone polymers do not lend themselves to this paradigm because acids or bases lead to siloxane equilibration and loss of structure. By contrast, elegant levels of control are possible when using the Piers-Rubinsztajn reaction and analogues, in which the hydrophobic, strong Lewis acid B(C 6 F 5 ) 3 activates SiH groups, permitting the synthesis of precise siloxanes under mild conditions in high yield; siloxane decomposition processes are slow under these conditions. A broad range of oxygen nucleophiles including alkoxysilanes, silanols, phenols, and aryl alkyl ethers participate in the reaction to create elastomers, foams and green composites, for example, derived from lignin. In addition, the process permits the synthesis of monofunctional dendrons that can be assembled into larger entities including highly branched silicones and dendrimers either using the Piers-Rubinsztajn process alone, or in combination with hydrosilylation or other orthogonal reactions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Silicon carbide semiconductor device fabrication and characterization

NASA Technical Reports Server (NTRS)

Davis, R. F.; Das, K.

1990-01-01

A number of basic building blocks i.e., rectifying and ohmic contacts, implanted junctions, MOS capacitors, pnpn diodes and devices, such as, MESFETs on both alpha and beta SiC films were fabricated and characterized. Gold forms a rectifying contact on beta SiC. Since Au contacts degrade at high temperatures, these are not considered to be suitable for high temperature device applications. However, it was possible to utilize Au contact diodes for electrically characterizing SiC films. Preliminary work indicates that sputtered Pt or Pt/Si contacts on beta SiC films are someways superior to Au contacts. Sputtered Pt layers on alpha SiC films form excellent rectifying contacts, whereas Ni layers following anneal at approximately 1050 C provide an ohmic contact. It has demonstrated that ion implantation of Al in substrates held at 550 C can be successfully employed for the fabrication of rectifying junction diodes. Feasibility of fabricating pnpn diodes and platinum gated MESFETs on alpha SiC films was also demonstrated.

Growth and characterization of molecular beam epitaxial GaAs layers on porous silicon

NASA Technical Reports Server (NTRS)

Lin, T. L.; Liu, J. K.; Sadwick, L.; Wang, K. L.; Kao, Y. C.

1987-01-01

GaAs layers have been grown on porous silicon (PS) substrates with good crystallinity by molecular beam epitaxy. In spite of the surface irregularity of PS substrates, no surface morphology deterioration was observed on epitaxial GaAs overlayers. A 10-percent Rutherford backscattering spectroscopy minimum channeling yield for GaAs-on-PS layers as compared to 16 percent for GaAs-on-Si layers grown under the same condition indicates a possible improvement of crystallinity when GaAs is grown on PS. Transmission electron microscopy reveals that the dominant defects in the GaAs-on-PS layers are microtwins and stacking faults, which originate from the GaAs/PS interface. GaAs is found to penetrate into the PS layers. n-type GaAs/p-type PS heterojunction diodes were fabricated with good rectifying characteristics.

Andreev rectifier: A nonlocal conductance signature of topological phase transitions

NASA Astrophysics Data System (ADS)

Rosdahl, T. Ö.; Vuik, A.; Kjaergaard, M.; Akhmerov, A. R.

2018-01-01

The proximity effect in hybrid superconductor-semiconductor structures, crucial for realizing Majorana edge modes, is complicated to control due to its dependence on many unknown microscopic parameters. In addition, defects can spoil the induced superconductivity locally in the proximitized system, which complicates measuring global properties with a local probe. We show how to use the nonlocal conductance between two spatially separated leads to probe three global properties of a proximitized system: the bulk superconducting gap, the induced gap, and the induced coherence length. Unlike local conductance spectroscopy, nonlocal conductance measurements distinguish between nontopological zero-energy modes localized around potential inhomogeneities, and true Majorana edge modes that emerge in the topological phase. In addition, we find that the nonlocal conductance is an odd function of bias at the topological phase transition, acting as a current rectifier in the low-bias limit. More generally, we identify conditions for crossed Andreev reflection to dominate the nonlocal conductance and show how to design a Cooper pair splitter in the open regime.

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

NASA Astrophysics Data System (ADS)

Okoshi, Masayuki; Iyono, Minako; Inoue, Narumi

2009-12-01

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

UV/ozone assisted local graphene (p)/ZnO(n) heterojunctions as a nanodiode rectifier

NASA Astrophysics Data System (ADS)

Sahatiya, Parikshit; Badhulika, Sushmee

2016-07-01

Here we report the fabrication of a novel graphene/ZnO nanodiode by UV/ozone assisted oxidation of graphene and demonstrate its application as a half-wave rectifier to generate DC voltage. The method involves the use of electrospinning for one-step in situ synthesis and alignment of single Gr/ZnO nanocomposite across metal electrodes. On subsequent UV illumination, graphene oxidizes, which induces p type doping and ZnO being an n type semiconductor, thus resulting in the formation of a nanodiode. The as-fabricated device shows strong non-linear current-voltage characteristic similar to that of conventional semiconductor p-n junction diodes. Excellent rectifying behavior with a rectification ratio of ~103 was observed and the nanodiodes were found to exhibit long-term repeatability in their performance. Ideality factor and barrier height, as calculated by the thermionic emission model, were found to be 1.6 and 0.504 eV respectively. Due to the fact that diodes are the basic building blocks in the electronics and semiconductor industry, the successful fabrication of these nanodiodes based on UV assisted p type doping of graphene indicates that this approach can be used for developing highly scalable and efficient components for nanoelectronics, such as rectifiers and logic gates that find applications in numerous fields.

Rectifiability of Line Defects in Liquid Crystals with Variable Degree of Orientation

NASA Astrophysics Data System (ADS)

Alper, Onur

2018-04-01

In [2], H ardt, L in and the author proved that the defect set of minimizers of the modified Ericksen energy for nematic liquid crystals consists locally of a finite union of isolated points and Hölder continuous curves with finitely many crossings. In this article, we show that each Hölder continuous curve in the defect set is of finite length. Hence, locally, the defect set is rectifiable. For the most part, the proof closely follows the work of D e L ellis et al. (Rectifiability and upper minkowski bounds for singularities of harmonic q-valued maps, arXiv:1612.01813, 2016) on harmonic Q-valued maps. The blow-up analysis in A lper et al. (Calc Var Partial Differ Equ 56(5):128, 2017) allows us to simplify the covering arguments in [11] and locally estimate the length of line defects in a geometric fashion.

p -n Junction Rectifying Characteristics of Purely n -Type GaN-Based Structures

NASA Astrophysics Data System (ADS)

Zuo, P.; Jiang, Y.; Ma, Z. G.; Wang, L.; Zhao, B.; Li, Y. F.; Yue, G.; Wu, H. Y.; Yan, H. J.; Jia, H. Q.; Wang, W. X.; Zhou, J. M.; Sun, Q.; Liu, W. M.; Ji, An-Chun; Chen, H.

2017-08-01

The GaN-based p -n junction rectifications are important in the development of high-power electronics. Here, we demonstrate that p -n junction rectifying characteristics can be realized with pure n -type structures by inserting an (In,Ga)N quantum well into the GaN /(Al ,Ga )N /GaN double heterostructures. Unlike the usual barriers, the insertion of an (In,Ga)N quantum well, which has an opposite polarization field to that of the (Al,Ga)N barrier, tailors significantly the energy bands of the system. The lifted energy level of the GaN spacer and the formation of the (In ,Ga )N /GaN interface barrier can improve the reverse threshold voltage and reduce the forward threshold voltage simultaneously, forming the p -n junction rectifying characteristics.

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

NASA Technical Reports Server (NTRS)

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

2014-01-01

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

Implementation of atomic layer etching of silicon: Scaling parameters, feasibility, and profile control

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

Ranjan, Alok, E-mail: alok.ranjan@us.tel.com; Wang, Mingmei; Sherpa, Sonam D.

2016-05-15

Atomic or layer by layer etching of silicon exploits temporally segregated self-limiting adsorption and material removal steps to mitigate the problems associated with continuous or quasicontinuous (pulsed) plasma processes: selectivity loss, damage, and profile control. Successful implementation of atomic layer etching requires careful choice of the plasma parameters for adsorption and desorption steps. This paper illustrates how process parameters can be arrived at through basic scaling exercises, modeling and simulation, and fundamental experimental tests of their predictions. Using chlorine and argon plasma in a radial line slot antenna plasma source as a platform, the authors illustrate how cycle time, ionmore » energy, and radical to ion ratio can be manipulated to manage the deviation from ideality when cycle times are shortened or purges are incomplete. Cell based Monte Carlo feature scale modeling is used to illustrate profile outcomes. Experimental results of atomic layer etching processes are illustrated on silicon line and space structures such that iso-dense bias and aspect ratio dependent free profiles are produced. Experimental results also illustrate the profile control margin as processes move from atomic layer to multilayer by layer etching. The consequence of not controlling contamination (e.g., oxygen) is shown to result in deposition and roughness generation.« less

Thermally controlled coupling of a rolled-up microtube integrated with a waveguide on a silicon electronic-photonic integrated circuit.

PubMed

Zhong, Qiuhang; Tian, Zhaobing; Veerasubramanian, Venkat; Dastjerdi, M Hadi Tavakoli; Mi, Zetian; Plant, David V

2014-05-01

We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up microtube and a waveguide on a silicon electronic-photonic integrated circuit. The microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the microtube and the waveguide using localized heaters, the microtube-waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0-6 V.

Large area silicon sheet by EFG

NASA Technical Reports Server (NTRS)

1977-01-01

Some hypotheses to explain both of these features are advanced and the possible implications for solar cell performance are touched upon. The multiple ribbon growth system has shown a number of flaws with respect to the reliability of the basic furnace design. These definitely need to be rectified before any significant demonstration of multiple ribbon growth can proceed. The cartridges, however, have performed quite well. The work on 3" cartridge design and automatic controls has proceeded nearly on schedule and the report contains a detailed description of the approach and the equipment to be used for automatic control of ribbon growth.

Impulse commutating circuit with transformer to limit reapplied voltage

NASA Technical Reports Server (NTRS)

Mcconville, J. H.

1973-01-01

Silicon controlled rectifier opens circuit with currents flowing up to values of 30 amperes. Switching concept halves both current and voltage in middle of commutating cycle thereby lowering size and weight requirements. Commutating circuit can be turned on or off by command and will remain on in absence of load due to continuous gate.

Test SCRs and Triacs with a Lab-Built Checker

ERIC Educational Resources Information Center

Harman, Charles

2010-01-01

Students enrolled in advanced electronics courses and/or industrial electronics classes at the high school level and at technical colleges ultimately learn about solid-state switches such as the SCR (silicon controlled rectifier) and the triac. Both the SCR and the triac are in a family of four-layer devices called thyristors. They are both…

20 kA PFN capacitor bank with solid-state switching. [pulse forming network for plasma studies

NASA Technical Reports Server (NTRS)

Posta, S. J.; Michels, C. J.

1973-01-01

A compact high-current pulse-forming network capacitor bank using paralleled silicon controlled rectifiers as switches is described. The maximum charging voltage of the bank is 1kV and maximum load current is 20 kA. The necessary switch equalization criteria and performance with dummy load and an arc plasma generator are described.

Ultra Thin Film Characterization of the Organic Rectifier Project

DTIC Science & Technology

1991-05-05

I % At%( I tAut 1 14 I - I. CONDL(rf 4IT M M[T T l I( I l%SL I A f%i, Rlf) l IJ " ()XYGE%-M ET L A Iro m N.6 t I) t t N,, sirt Poi ti ki rk ,L I uqh...befrlfatsos in about 1981, to realize the Asiram-Ranter rectifier, one ofr opc im.rtfeil nuh so as transfer well (hr the vertical dipping method) as LB

Intermediate Bandgap Solar Cells From Nanostructured Silicon

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

Black, Marcie

2014-10-30

This project aimed to demonstrate increased electronic coupling in silicon nanostructures relative to bulk silicon for the purpose of making high efficiency intermediate bandgap solar cells using silicon. To this end, we formed nanowires with controlled crystallographic orientation, small diameter, <111> sidewall faceting, and passivated surfaces to modify the electronic band structure in silicon by breaking down the symmetry of the crystal lattice. We grew and tested these silicon nanowires with <110>-growth axes, which is an orientation that should produce the coupling enhancement.

[Effect of surface organic modified nano-silicon-oxide on mechanical properties of A-2186 silicone elastomers].

PubMed

Guo, Nan; Jiao, Ting

2011-08-01

To study the effect of surface organic modified nano-silicon-oxide (SiO(x)) on mechanical properties of A-2186 silicone elastomers. Surface organic modified nano-silicon-oxide (SiO(x)) was added into A-2186 silicone elastomers by weight percentage of 2%, 4% and 6%. The one without addition served as a control. Standard specimens were made according to American Society for Testing Materials (ASTM). Their tensile strength, elongation at break, tear strength, and Shore A hardness were measured. The results were analyzed statistically by SPSS 10.0 software package. The tensile strength in the experimental groups was significantly lower than the control group (P<0.001).The elongation in the experimental groups was lower than the control group, but there was no significant difference between the 2wt% group and the control group (P=0.068). The tear strength in both the 2wt= group and 4wt= group were higher than the control group, and the difference was statistically significant; in addition, the tear strength in 2wt= group was higher than 4wt= group, which also showed statistical significance (P<0.001). With the increase of the added amount of surface modified nano-SiO(x), Shore A hardness increased and there was significant difference among them (P<0.001). Adding surface modified nano-SiO(x) has an effect on mechanical properties of A-2186 silicone elastomer, when 2wt= and 4wt= are added, tear strength of A-2186 improves significantly, with an increase of Shore A hardness and an decrease of tensile strength.

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds

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

Horie, Hiro-omi; Kikudome, Takashi; Teramura, Kyosuke

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

A Vertical Diffusion Scheme to estimate the atmospheric rectifier effect

NASA Astrophysics Data System (ADS)

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

2004-02-01

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

All-electric control of donor nuclear spin qubits in silicon

NASA Astrophysics Data System (ADS)

Sigillito, Anthony J.; Tyryshkin, Alexei M.; Schenkel, Thomas; Houck, Andrew A.; Lyon, Stephen A.

2017-10-01

The electronic and nuclear spin degrees of freedom of donor impurities in silicon form ultra-coherent two-level systems that are potentially useful for applications in quantum information and are intrinsically compatible with industrial semiconductor processing. However, because of their smaller gyromagnetic ratios, nuclear spins are more difficult to manipulate than electron spins and are often considered too slow for quantum information processing. Moreover, although alternating current magnetic fields are the most natural choice to drive spin transitions and implement quantum gates, they are difficult to confine spatially to the level of a single donor, thus requiring alternative approaches. In recent years, schemes for all-electrical control of donor spin qubits have been proposed but no experimental demonstrations have been reported yet. Here, we demonstrate a scalable all-electric method for controlling neutral 31P and 75As donor nuclear spins in silicon. Using coplanar photonic bandgap resonators, we drive Rabi oscillations on nuclear spins exclusively using electric fields by employing the donor-bound electron as a quantum transducer, much in the spirit of recent works with single-molecule magnets. The electric field confinement leads to major advantages such as low power requirements, higher qubit densities and faster gate times. Additionally, this approach makes it possible to drive nuclear spin qubits either at their resonance frequency or at its first subharmonic, thus reducing device bandwidth requirements. Double quantum transitions can be driven as well, providing easy access to the full computational manifold of our system and making it convenient to implement nuclear spin-based qudits using 75As donors.

Simulation and Analysis of Three-Phase Rectifiers for Aerospace Power Applications

NASA Technical Reports Server (NTRS)

Truong, Long V.; Birchenough, Arthur G.

2004-01-01

Due to the nature of planned planetary missions, fairly large advanced power systems are required for the spacecraft. These future high power spacecrafts are expected to use dynamic power conversion systems incorporating high speed alternators as three-phase AC electrical power source. One of the early design considerations in such systems is the type of rectification to be used with the AC source for DC user loads. This paper address the issues involved with two different rectification methods, namely the conventional six and twelve pulses. Two circuit configurations which involved parallel combinations of the six and twelve-pulse rectifiers were selected for the simulation. The rectifier s input and output power waveforms will be thoroughly examined through simulations. The effects of the parasitic load for power balancing and filter components for reducing the ripple voltage at the DC loads are also included in the analysis. Details of the simulation circuits, simulation results, and design examples for reducing risk from damaging of spacecraft engines will be presented and discussed.

Control of grown-in defects and oxygen precipitates in silicon wafers with DZ-IG structure by ultrahigh-temperature rapid thermal oxidation

NASA Astrophysics Data System (ADS)

Maeda, Susumu; Sudo, Haruo; Okamura, Hideyuki; Nakamura, Kozo; Sueoka, Koji; Izunome, Koji

2018-04-01

A new control technique for achieving compatibility between crystal quality and gettering ability for heavy metal impurities was demonstrated for a nitrogen-doped Czochralski silicon wafer with a diameter of 300 mm via ultra-high temperature rapid thermal oxidation (UHT-RTO) processing. We have found that the DZ-IG structure with surface denuded zone and the wafer bulk with dense oxygen precipitates were formed by the control of vacancies in UHT-RTO process at temperature exceeding 1300 °C. It was also confirmed that most of the void defects were annihilated from the sub-surface of the wafer due to the interstitial Si atoms that were generated at the SiO2/Si interface. These results indicated that vacancies corresponded to dominant species, despite numerous interstitial silicon injections. We have explained these prominent features by the degree of super-saturation for the interstitial silicon due to oxidation and the precise thermal properties of the vacancy and interstitial silicon.

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

PubMed Central

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

2013-01-01

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

Brownian trail rectified

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Ho, Pauline

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(-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.

Characterization of hydrogenated amorphous silicon films obtained from rice husk

NASA Astrophysics Data System (ADS)

Nandi, K. C.; Mukherjee, D.; Biswas, A. K.; Acharya, H. N.

1991-08-01

Hydrogenated amorphous silicon ( a-Si: H) films were prepared by chemical vapour deposition (CVD) of silanes generated by the acid hydrolysis of magnesium silicide (Mg 2Si) obtained from rice husk. The films were deposited at various substrate temperatures ( Ts) ranging from 430 to 520°C. The results show that the films have room temperature (294 K) dark conductivity (σ d) of the order of 10 -8 - 10 -10 (ohm-cm) -1 with single activation energy (Δ Ed) and the photoconductivity (σ ph) decreases with increase of Ts. Optical band gap ( Eopt) lies between 1.60-1.73 eV and hydrogen content ( CH) in the films is at best 8.3 at %. Au/ a-Si: H junction shows that it acts as a rectifier contact with Schottky barrier height ( VB) 0.69 eV. The films are contaminated by traces of impurities like Na, K, Al, Cl and O as revealed by secondary ion mass spectrometric (SIMS) analysis.

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

NASA Astrophysics Data System (ADS)

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

2010-10-01

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).

Colloidal characterization of silicon nitride and silicon carbide

NASA Technical Reports Server (NTRS)

Feke, Donald L.

1986-01-01

The colloidal behavior of aqueous ceramic slips strongly affects the forming and sintering behavior and the ultimate mechanical strength of the final ceramic product. The colloidal behavior of these materials, which is dominated by electrical interactions between the particles, is complex due to the strong interaction of the solids with the processing fluids. A surface titration methodology, modified to account for this interaction, was developed and used to provide fundamental insights into the interfacial chemistry of these systems. Various powder pretreatment strategies were explored to differentiate between true surface chemistry and artifacts due to exposure history. The colloidal behavior of both silicon nitride and carbide is dominated by silanol groups on the powder surfaces. However, the colloid chemistry of silicon nitride is apparently influenced by an additional amine group. With the proper powder treatments, silicon nitride and carbide powder can be made to appear colloidally equivalent. The impact of these results on processing control will be discussed.

Silicon nitride/silicon carbide composite powders

DOEpatents

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

1996-06-11

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.

‘Sleepy’ inward rectifier channels in guinea-pig cardiomyocytes are activated only during strong hyperpolarization

PubMed Central

Liu, Gong Xin; Daut, Jürgen

2002-01-01

K+ channels of isolated guinea-pig cardiomyocytes were studied using the patch-clamp technique. At transmembrane potentials between −120 and −220 mV we observed inward currents through an apparently novel channel. The novel channel was strongly rectifying, no outward currents could be recorded. Between −200 and −160 mV it had a slope conductance of 42.8 ± 3.0 pS (s.d.; n = 96). The open probability (Po) showed a sigmoid voltage dependence and reached a maximum of 0.93 at −200 mV, half-maximal activation was approximately −150 mV. The voltage dependence of Po was not affected by application of 50 μm isoproterenol. The open-time distribution could be described by a single exponential function, the mean open time ranged between 73.5 ms at −220 mV and 1.4 ms at −160 mV. At least two exponential components were required to fit the closed time distribution. Experiments with different external Na+, K+ and Cl− concentrations suggested that the novel channel is K+ selective. Extracellular Ba2+ ions gave rise to a voltage-dependent reduction in Po by inducing long closed states; Cs+ markedly reduced mean open time at −200 mV. In cell-attached recordings the novel channel frequently converted to a classical inward rectifier channel, and vice versa. This conversion was not voltage dependent. After excision of the patch, the novel channel always converted to a classical inward rectifier channel within 0–3 min. This conversion was not affected by intracellular Mg2+, phosphatidylinositol (4,5)-bisphosphate or spermine. Taken together, our findings suggest that the novel K+ channel represents a different ‘mode’ of the classical inward rectifier channel in which opening occurs only at very negative potentials. PMID:11897847

Contribution of delayed rectifier potassium currents to the electrical activity of murine colonic smooth muscle

PubMed Central

Koh, S D; Ward, S M; Dick, G M; Epperson, A; Bonner, H P; Sanders, K M; Horowitz, B; Kenyon, J L

1999-01-01

We used intracellular microelectrodes to record the membrane potential (Vm) of intact murine colonic smooth muscle. Electrical activity consisted of spike complexes separated by quiescent periods (Vm≈−60 mV). The spike complexes consisted of about a dozen action potentials of approximately 30 mV amplitude. Tetraethylammonium (TEA, 1–10 mM) had little effect on the quiescent periods but increased the amplitude of the action potential spikes. 4-Aminopyridine (4-AP, ⋧ 5 mM) caused continuous spiking.Voltage clamp of isolated myocytes identified delayed rectifier K+ currents that activated rapidly (time to half-maximum current, 11.5 ms at 0 mV) and inactivated in two phases (τf = 96 ms, τs = 1.5 s at 0 mV). The half-activation voltage of the permeability was −27 mV, with significant activation at −50 mV.TEA (10 mM) reduced the outward current at potentials positive to 0 mV. 4-AP (5 mM) reduced the early current but increased outward current at later times (100–500 ms) consistent with block of resting channels relieved by depolarization. 4-AP inhibited outward current at potentials negative to −20 mV, potentials where TEA had no effect.Qualitative PCR amplification of mRNA identified transcripts encoding delayed rectifier K+ channel subunits Kv1.6, Kv4.1, Kv4.2, Kv4.3 and the Kvβ1.1 subunit in murine colon myocytes. mRNA encoding Kv 1.4 was not detected.We find that TEA-sensitive delayed rectifier currents are important determinants of action potential amplitude but not rhythmicity. Delayed rectifier currents sensitive to 4-AP are important determinants of rhythmicity but not action potential amplitude. PMID:10050014

Single-molecule designs for electric switches and rectifiers.

PubMed

Kornilovitch, Pavel; Bratkovsky, Alexander; Williams, Stanley

2003-12-01

A design for molecular rectifiers is proposed. Current rectification is based on the spatial asymmetry of a molecule and requires only one resonant conducting molecular orbital. Rectification is caused by asymmetric coupling of the orbital to the electrodes, which results in asymmetric movement of the two Fermi levels with respect to the orbital under external bias. Results from numerical studies of the family of suggested molecular rectifiers, HS-(CH(2))(n)-C(6)H(4)(CH(2))(m)SH, are presented. Current rectification ratios in excess of 100 are achievable for n = 2 and m > 6. A class of bistable stator-rotor molecules is proposed. The stationary part connects the two electrodes and facilitates electron transport between them. The rotary part, which has a large dipole moment, is attached to an atom of the stator via a single sigma bond. Electrostatic bonds formed between the oxygen atom of the rotor and hydrogen atoms of the stator make the symmetric orientation of the dipole unstable. The rotor has two potential minima with equal energy for rotation about the sigma bond. The dipole can be flipped between the two states by an external electric field. Both rotor-orientation states have asymmetric current-voltage characteristics that are the reverse of each other, so they are distinguishable electrically. Theoretical results on conformation, energy barriers, retention times, switching voltages, and current-voltage characteristics are presented for a particular stator-rotor molecule. Such molecules could be the base for single-molecule switches, reversible diodes, and other molecular electronic devices.

Core-shell heterojunction of silicon nanowire arrays and carbon quantum dots for photovoltaic devices and self-driven photodetectors.

PubMed

Xie, Chao; Nie, Biao; Zeng, Longhui; Liang, Feng-Xia; Wang, Ming-Zheng; Luo, Linbao; Feng, Mei; Yu, Yongqiang; Wu, Chun-Yan; Wu, Yucheng; Yu, Shu-Hong

2014-04-22

Silicon nanostructure-based solar cells have lately intrigued intensive interest because of their promising potential in next-generation solar energy conversion devices. Herein, we report a silicon nanowire (SiNW) array/carbon quantum dot (CQD) core-shell heterojunction photovoltaic device by directly coating Ag-assisted chemical-etched SiNW arrays with CQDs. The heterojunction with a barrier height of 0.75 eV exhibited excellent rectifying behavior with a rectification ratio of 10(3) at ±0.8 V in the dark and power conversion efficiency (PCE) as high as 9.10% under AM 1.5G irradiation. It is believed that such a high PCE comes from the improved optical absorption as well as the optimized carrier transfer and collection capability. Furthermore, the heterojunction could function as a high-performance self-driven visible light photodetector operating in a wide switching wavelength with good stability, high sensitivity, and fast response speed. It is expected that the present SiNW array/CQD core-shell heterojunction device could find potential applications in future high-performance optoelectronic devices.

Simplified High-Power Inverter

NASA Technical Reports Server (NTRS)

Edwards, D. B.; Rippel, W. E.

1984-01-01

Solid-state inverter simplified by use of single gate-turnoff device (GTO) to commutate multiple silicon controlled rectifiers (SCR's). By eliminating conventional commutation circuitry, GTO reduces cost, size and weight. GTO commutation applicable to inverters of greater than 1-kilowatt capacity. Applications include emergency power, load leveling, drives for traction and stationary polyphase motors, and photovoltaic-power conditioning.

Size Control of Porous Silicon-Based Nanoparticles via Pore-Wall Thinning.

PubMed

Secret, Emilie; Leonard, Camille; Kelly, Stefan J; Uhl, Amanda; Cozzan, Clayton; Andrew, Jennifer S

2016-02-02

Photoluminescent silicon nanocrystals are very attractive for biomedical and electronic applications. Here a new process is presented to synthesize photoluminescent silicon nanocrystals with diameters smaller than 6 nm from a porous silicon template. These nanoparticles are formed using a pore-wall thinning approach, where the as-etched porous silicon layer is partially oxidized to silica, which is dissolved by a hydrofluoric acid solution, decreasing the pore-wall thickness. This decrease in pore-wall thickness leads to a corresponding decrease in the size of the nanocrystals that make up the pore walls, resulting in the formation of smaller nanoparticles during sonication of the porous silicon. Particle diameters were measured using dynamic light scattering, and these values were compared with the nanocrystallite size within the pore wall as determined from X-ray diffraction. Additionally, an increase in the quantum confinement effect is observed for these particles through an increase in the photoluminescence intensity of the nanoparticles compared with the as-etched nanoparticles, without the need for a further activation step by oxidation after synthesis.

Gluing silicon with silicone

NASA Astrophysics Data System (ADS)

Abt, I.; Fox, H.; Moshous, B.; Richter, R. H.; Riechmann, K.; Rietz, M.; Riedl, J.; Denis, R. St; Wagner, W.

1998-02-01

Problems and solutions concerning the gluing of silicon detectors are discussed. The R & D work for the HERA- B vertex detector system led to gluing studies with epoxy and silicone-based adhesives used on ceramics and carbon fibre. The HERA- B solution using a silicone glue is presented.

A pulsed load model and its impact on a synchronous-rectifier system

NASA Astrophysics Data System (ADS)

Hou, Pengfei; Xu, Ye; Li, Jianke; Wang, Jinquan; Zhang, Haitao; Yan, Jun; Wang, Chunming; Chen, Jingjing

2017-02-01

The pulsed load has become a developing trend of power loading. Unlike traditional loads, pulsed loads with current abrupt and repeated charges will result in unstable Microgrid operations because of their small capacity and inertia. In this paper, an Average Magnitude Sum Function (AMSF) is proposed to calculate the frequency of the grid, and based on AMSF, the Relative Deviation Rate (RDR) that characterises the impact of pulsed load on the AC side of the grid is defined and its calculation process is described in detail. In addition, the system dynamic characteristics under a pulsed load are analysed using an Insulated Gate Bipolar Transistor (IGBT) to control the on/off state of the resistive load for simulating a pulsed load. Finally, the transient characteristics of a synchronous-rectifier system with a pulsed load are studied and validated experimentally.

Photoperiod Modulates Fast Delayed Rectifier Potassium Currents in the Mammalian Circadian Clock.

PubMed

Farajnia, Sahar; Meijer, Johanna H; Michel, Stephan

2016-10-01

One feature of the mammalian circadian clock, situated in the suprachiasmatic nucleus (SCN), is its ability to measure day length and thereby contribute to the seasonal adaptation of physiology and behavior. The timing signal from the SCN, namely the 24 hr pattern of electrical activity, is adjusted according to the photoperiod being broader in long days and narrower in short days. Vasoactive intestinal peptide and gamma-aminobutyric acid play a crucial role in intercellular communication within the SCN and contribute to the seasonal changes in phase distribution. However, little is known about the underlying ionic mechanisms of synchronization. The present study was aimed to identify cellular mechanisms involved in seasonal encoding by the SCN. Mice were adapted to long-day (light-dark 16:8) and short-day (light-dark 8:16) photoperiods and membrane properties as well as K + currents activity of SCN neurons were measured using patch-clamp recordings in acute slices. Remarkably, we found evidence for a photoperiodic effect on the fast delayed rectifier K + current, that is, the circadian modulation of this ion channel's activation reversed in long days resulting in 50% higher peak values during the night compared with the unaltered day values. Consistent with fast delayed rectifier enhancement, duration of action potentials during the night was shortened and afterhyperpolarization potentials increased in amplitude and duration. The slow delayed rectifier, transient K + currents, and membrane excitability were not affected by photoperiod. We conclude that photoperiod can change intrinsic ion channel properties of the SCN neurons, which may influence cellular communication and contribute to photoperiodic phase adjustment. © The Author(s) 2016.

Continuous coating of silicon-on-ceramic

NASA Technical Reports Server (NTRS)

Heaps, J. D.; Schuldt, S. B.; Grung, B. L.; Zook, J. D.; Butter, C. D.

1980-01-01

Growth of sheet silicon on low-cost substrates has been demonstrated by the silicon coating with inverted meniscus (SCIM) technique. A mullite-based ceramic substrate is coated with carbon and then passed over a trough of molten silicon with a raised meniscus. Solidification occurs at the trailing edge of the downstream meniscus, producing a silicon-on-ceramic (SOC) layer. Meniscus shape and stability are controlled by varying the level of molten silicon in a reservoir connected to the trough. The thermal conditions for growth and the crystallographic texture of the SOC layers are similar to those produced by dip-coating, the original technique of meniscus-controlled growth. The thermal conditions for growth have been analyzed in some detail. The analysis correctly predicts the velocity-thickness relationship and the liquid-solid interface shape for dip-coating, and appears to be equally applicable to SCIM-coating. Solar cells made from dip-coated SOC material have demonstrated efficiencies of 10% on 4-sq cm cells and 9.9% on 10-sq cm cells.

A transparent diode with high rectifying ratio using amorphous indium-gallium-zinc oxide/SiN{sub x} coupled junction

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

Choi, Myung-Jea; Kim, Myeong-Ho; Choi, Duck-Kyun, E-mail: duck@hanyang.ac.kr

2015-08-03

We introduce a transparent diode that shows both high rectifying ratio and low leakage current at process temperature below 250 °C. This device is clearly distinguished from all previous transparent diodes in that the rectifying behavior results from the junction between a semiconductor (amorphous indium-gallium-zinc oxide (a-IGZO)) and insulator (SiN{sub x}). We systematically study the properties of each junction within the device structure and demonstrate that the a-IGZO/SiN{sub x} junction is the source of the outstanding rectification. The electrical characteristics of this transparent diode are: 2.8 A/cm{sup 2} on-current density measured at −7 V; lower than 7.3 × 10{sup −9} A/cm{sup 2} off-currentmore » density; 2.53 ideality factor; and high rectifying ratio of 10{sup 8}–10{sup 9}. Furthermore, the diode structure has a transmittance of over 80% across the visible light range. The operating principle of the indium-tin oxide (ITO)/a-IGZO/SiN{sub x}/ITO device was examined with an aid of the energy band diagram and we propose a preliminary model for the rectifying behavior. Finally, we suggest further directions for research on this transparent diode.« less

Large-Area Direct Hetero-Epitaxial Growth of 1550-nm InGaAsP Multi-Quantum-Well Structures on Patterned Exact-Oriented (001) Silicon Substrates by Metal Organic Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Megalini, Ludovico; Cabinian, Brian C.; Zhao, Hongwei; Oakley, Douglas C.; Bowers, John E.; Klamkin, Jonathan

2018-02-01

We employ a simple two-step growth technique to grow large-area 1550-nm laser structures by direct hetero-epitaxy of III-V compounds on patterned exact-oriented (001) silicon (Si) substrates by metal organic chemical vapor deposition. Densely-packed, highly uniform, flat and millimeter-long indium phosphide (InP) nanowires were grown from Si v-grooves separated by silicon dioxide (SiO2) stripes with various widths and pitches. Following removal of the SiO2 patterns, the InP nanowires were coalesced and, subsequently, 1550-nm laser structures were grown in a single overgrowth without performing any polishing for planarization. X-ray diffraction, photoluminescence, atomic force microscopy and transmission electron microscopy analyses were used to characterize the epitaxial material. PIN diodes were fabricated and diode-rectifying behavior was observed.

Open Air Silicon Deposition by Atmospheric Pressure Plasma under Local Ambient Gas Control

NASA Astrophysics Data System (ADS)

Naito, Teruki; Konno, Nobuaki; Yoshida, Yukihisa

2015-09-01

In this paper, we report open air silicon (Si) deposition by combining a silane free Si deposition technology and a newly developed local ambient gas control technology. Recently, material processing in open air has been investigated intensively. While a variety of materials have been deposited, there were only few reports on Si deposition due to the susceptibility to contamination and the hazardous nature of source materials. Since Si deposition is one of the most important processes in device fabrication, we have developed open air silicon deposition technologies in BEANS project. For a clean and safe process, a local ambient gas control head was designed. Process gas leakage was prevented by local evacuation, and air contamination was shut out by inert curtain gas. By numerical and experimental investigations, a safe and clean process condition with air contamination less than 10 ppm was achieved. Si film was deposited in open air by atmospheric pressure plasma enhanced chemical transport under the local ambient gas control. The film was microcrystalline Si with the crystallite size of 17 nm, and the Hall mobility was 2.3 cm2/V .s. These properties were comparable to those of Si films deposited in a vacuum chamber. This research has been conducted as one of the research items of New Energy and Industrial Technology Development Organization ``BEANS'' project.

INCREASED VOLUNTARY DRIVE IS ASSOCIATED WITH CHANGES IN COMMON OSCILLATIONS FROM 13 TO 60 HZ OF INTERFERENCE BUT NOT RECTIFIED ELECTROMYOGRAPHY

PubMed Central

NETO, OSMAR P.; BAWEJA, HARSIMRAN S.; CHRISTOU, EVANGELOS A.

2013-01-01

The purpose of this study was to compare the capability of interference and rectified electromyography (EMG) to detect changes in the beta (13–30-HZ) and Piper (30–60-HZ) bands when voluntary force is increased. Twenty adults exerted a constant force abduction of the index finger at 15% and 50% of maximum. The common oscillations at various frequency bands (0–500 HZ) were estimated from the first dorsal interosseous muscle using cross wavelets of interference and rectified EMG. For the interference EMG signals, normalized power significantly (P < 0.01) increased with force in the beta (9.0 ± 0.9 vs. 15.5 ± 2.1%) and Piper (13.6 ± 0.9 vs. 21 ± 1.7%) bands. For rectified EMG signals, however, the beta and Piper bands remained unchanged (P > 0.4). Although rectified EMG is used in many clinical studies to identify changes in the oscillatory drive to the muscle, our findings suggest that only interference EMG can accurately capture the increase in oscillatory drive from 13 to 60 HZ with voluntary force. PMID:20589885

Custom 3D Printable Silicones with Tunable Stiffness

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

Durban, Matthew M.; Lenhardt, Jeremy M.; Wu, Amanda S.

Silicone elastomers have broad versatility within a variety of potential advanced materials applications, such as soft robotics, biomedical devices, and metamaterials. Furthermore, a series of custom 3D printable silicone inks with tunable stiffness is developed, formulated, and characterized. The silicone inks exhibit excellent rheological behavior for 3D printing, as observed from the printing of porous structures with controlled architectures. Here, the capability to tune the stiffness of printable silicone materials via careful control over the chemistry, network formation, and crosslink density of the ink formulations in order to overcome the challenging interplay between ink development, post-processing, material properties, and performancemore » is demonstrated.« less

Custom 3D Printable Silicones with Tunable Stiffness

DOE PAGES

Durban, Matthew M.; Lenhardt, Jeremy M.; Wu, Amanda S.; ...

2017-12-06

Silicone elastomers have broad versatility within a variety of potential advanced materials applications, such as soft robotics, biomedical devices, and metamaterials. Furthermore, a series of custom 3D printable silicone inks with tunable stiffness is developed, formulated, and characterized. The silicone inks exhibit excellent rheological behavior for 3D printing, as observed from the printing of porous structures with controlled architectures. Here, the capability to tune the stiffness of printable silicone materials via careful control over the chemistry, network formation, and crosslink density of the ink formulations in order to overcome the challenging interplay between ink development, post-processing, material properties, and performancemore » is demonstrated.« less

Process for forming a porous silicon member in a crystalline silicon member

DOEpatents

Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.

1999-01-01

Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific pore size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased pressure for thermopneumatic actuation of integrated membranes. Examples that benefit from specific pore sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.

Innovative remotely-controlled bending device for thin silicon and germanium crystals

NASA Astrophysics Data System (ADS)

De Salvador, D.; Carturan, S.; Mazzolari, A.; Bagli, E.; Bandiera, L.; Durighello, C.; Germogli, G.; Guidi, V.; Klag, P.; Lauth, W.; Maggioni, G.; Romagnoni, M.; Sytov, A.

2018-04-01

Steering of negatively charged particle beams below 1 GeV has demonstrated to be possible with thin bent silicon and germanium crystals. A newly designed mechanical holder was used for bending crystals, since it allows a remotely-controlled adjustment of crystal bending and compensation of unwanted torsion. Bent crystals were installed and tested at the MAMI Mainz MIcrotron to achieve steering of 0.855-GeV electrons at different bending radii. We report the description and characterization of the innovative bending device developed at INFN Laboratori Nazionali di Legnaro (LNL).

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

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

Wang, Ruxi; Wang, Fei; Boroyevich, Dushan

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 schemesmore » 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.« less

"Silicon millefeuille": From a silicon wafer to multiple thin crystalline films in a single step

NASA Astrophysics Data System (ADS)

Hernández, David; Trifonov, Trifon; Garín, Moisés; Alcubilla, Ramon

2013-04-01

During the last years, many techniques have been developed to obtain thin crystalline films from commercial silicon ingots. Large market applications are foreseen in the photovoltaic field, where important cost reductions are predicted, and also in advanced microelectronics technologies as three-dimensional integration, system on foil, or silicon interposers [Dross et al., Prog. Photovoltaics 20, 770-784 (2012); R. Brendel, Thin Film Crystalline Silicon Solar Cells (Wiley-VCH, Weinheim, Germany 2003); J. N. Burghartz, Ultra-Thin Chip Technology and Applications (Springer Science + Business Media, NY, USA, 2010)]. Existing methods produce "one at a time" silicon layers, once one thin film is obtained, the complete process is repeated to obtain the next layer. Here, we describe a technology that, from a single crystalline silicon wafer, produces a large number of crystalline films with controlled thickness in a single technological step.

Impurities in silicon solar cells

NASA Technical Reports Server (NTRS)

Hopkins, R. H.

1985-01-01

Metallic impurities, both singly and in combinations, affect the performance of silicon solar cells. Czochralski silicon web crystals were grown with controlled additions of secondary impurities. The primary electrical dopants were boron and phosphorus. The silicon test ingots were grown under controlled and carefully monitored conditions from high-purity charge and dopant material to minimize unintentional contamination. Following growth, each crystal was characterized by chemical, microstructural, electrical, and solar cell tests to provide a detailed and internally consistent description of the relationships between silicon impurity concentration and solar cell performance. Deep-level spectroscopy measurements were used to measure impurity concentrations at levels below the detectability of other techniques and to study thermally-induced changes in impurity activity. For the majority of contaminants, impurity-induced performance loss is due to a reduction of the base diffusion length. From these observations, a semi-empirical model which predicts cell performance as a function of metal impurity concentration was formulated. The model was then used successfully to predict the behavior of solar cells bearing as many as 11 different impurities.

Formation of iron disilicide on amorphous silicon

NASA Astrophysics Data System (ADS)

Erlesand, U.; Östling, M.; Bodén, K.

1991-11-01

Thin films of iron disilicide, β-FeSi 2 were formed on both amorphous silicon and on crystalline silicon. The β-phase is reported to be semiconducting with a direct band-gap of about 0.85-0.89 eV. This phase is known to form via a nucleation-controlled growth process on crystalline silicon and as a consequence a rather rough silicon/silicide interface is usually formed. In order to improve the interface a bilayer structure of amorphous silicon and iron was sequentially deposited on Czochralski <111> silicon in an e-gun evaporation system. Secondary ion mass spectrometry profiling (SIMS) and scanning electron micrographs revealed an improvement of the interface sharpness. Rutherford backscattering spectrometry (RBS) and X-ray diffractiometry showed β-FeSi 2 formation already at 525°C. It was also observed that the silicide growth was diffusion-controlled, similar to what has been reported for example in the formation of NiSi 2 for the reaction of nickel on amorphous silicon. The kinetics of the FeSi 2 formation in the temperature range 525-625°C was studied by RBS and the activation energy was found to be 1.5 ± 0.1 eV.

Cytotoxicity control of silicon nanoparticles by biopolymer coating and ultrasound irradiation for cancer theranostic applications

NASA Astrophysics Data System (ADS)

Sviridov, A. P.; Osminkina, L. A.; Kharin, A. Yu; Gongalsky, M. B.; Kargina, J. V.; Kudryavtsev, A. A.; Bezsudnova, Yu I.; Perova, T. S.; Geloen, A.; Lysenko, V.; Timoshenko, V. Yu

2017-03-01

Silicon nanoparticles (SiNPs) prepared by mechanical grinding of luminescent porous silicon were coated with a biopolymer (dextran) and investigated as a potential theranostic agent for bioimaging and sonodynamic therapy. Transmission electron microscopy, photoluminescence and Raman scattering measurements of dextran-coated SiNPs gave evidence of their enhanced stability in water. In vitro experiments confirmed the lower cytotoxicity of the dextran-coated NPs in comparison with uncoated ones, especially for high concentrations of about 2 mg ml-1. Efficient uptake of the NPs by cancer cells was found using bioimaging in the optical transmittance and photoluminescence modes. Treatment of the cells with uptaken SiNPs by therapeutic ultrasound for 5-20 min resulted in a strong decrease in the number of living cells, while the total number of cells remained nearly unchanged. The obtained data indicate a ‘mild’ effect of the combined action of ultrasonic irradiation and SiNPs on cancer cells. The observed results reveal new opportunities for controlling the photoluminescent and sonosensitizing properties of silicon-based NPs for applications in the diagnostics and mild therapy of cancer.

Oscillations in motor unit discharge are reflected in the low-frequency component of rectified surface EMG and the rate of change in force.

PubMed

Yoshitake, Yasuhide; Shinohara, Minoru

2013-11-01

Common drive to a motor unit (MU) pool manifests as low-frequency oscillations in MU discharge rate, producing fluctuations in muscle force. The aim of the study was to examine the temporal correlation between instantaneous MU discharge rate and rectified EMG in low frequencies. Additionally, we attempted to examine whether there is a temporal correlation between the low-frequency oscillations in MU discharge rate and the first derivative of force (dF/dt). Healthy young subjects produced steady submaximal force with their right finger as a single task or while maintaining a pinch-grip force with the left hand as a dual task. Surface EMG and fine-wire MU potentials were recorded from the first dorsal interosseous muscle in the right hand. Surface EMG was band-pass filtered (5-1,000 Hz) and full-wave rectified. Rectified surface EMG and the instantaneous discharge rate of MUs were smoothed by a Hann-window of 400 ms duration (equivalent to 2 Hz low-pass filtering). In each of the identified MUs, the smoothed MU discharge rate was positively correlated with the rectified-and-smoothed EMG as confirmed by the distinct peak in cross-correlation function with greater values in the dual task compared with the single task. Additionally, the smoothed MU discharge rate was temporally correlated with dF/dt more than with force and with rectified-and-smoothed EMG. The results indicated that the low-frequency component of rectified surface EMG and the first derivative of force provide temporal information on the low-frequency oscillations in the MU discharge rate.

Method of purifying metallurgical grade silicon employing reduced pressure atmospheric control

NASA Technical Reports Server (NTRS)

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

1979-01-01

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

Silicon Carbide Integrated Circuit Chip

NASA Image and Video Library

2015-02-17

A multilevel interconnect silicon carbide integrated circuit chip with co-fired ceramic package and circuit board recently developed at the NASA GRC Smart Sensors and Electronics Systems Branch for high temperature applications. High temperature silicon carbide electronics and compatible packaging technologies are elements of instrumentation for aerospace engine control and long term inner-solar planet explorations.

Au/n-ZnO rectifying contact fabricated with hydrogen peroxide pretreatment

NASA Astrophysics Data System (ADS)

Gu, Q. L.; Cheung, C. K.; Ling, C. C.; Ng, A. M. C.; Djurišić, A. B.; Lu, L. W.; Chen, X. D.; Fung, S.; Beling, C. D.; Ong, H. C.

2008-05-01

Au contacts were deposited on n-type ZnO single crystals with and without hydrogen peroxide pretreatment for the ZnO substrate. The Au/ZnO contacts fabricated on substrates without H2O2 pretreatment were Ohmic and those with H2O2 pretreatment were rectifying. With an aim of fabricating a good quality Schottky contact, the rectifying property of the Au/ZnO contact was systemically investigated by varying the treatment temperature and duration. The best performing Schottky contact was found to have an ideality factor of 1.15 and a leakage current of ˜10-7 A cm-2. A multispectroscopic study, including scanning electron microscopy, positron annihilation spectroscopy, deep level transient spectroscopy, x-ray photoelectron spectroscopy, and photoluminescence, showed that the H2O2 treatment removed the OH impurity and created Zn-vacancy related defects hence decreasing the conductivity of the ZnO surface layer, a condition favorable for forming good Schottky contact. However, the H2O2 treatment also resulted in a deterioration of the surface morphology, leading to an increase in the Schottky contact ideality factor and leakage current in the case of nonoptimal treatment time and temperature.

Regulation of the instantaneous inward rectifier and the delayed outward rectifier potassium channels by Captopril and Angiotensin II via the Phosphoinositide-3 kinase pathway in volume-overload-induced hypertrophied cardiac myocytes.

PubMed

Alvin, Zikiar V; Laurence, Graham G; Coleman, Bernell R; Zhao, Aiqiu; Hajj-Moussa, Majd; Haddad, Georges E

2011-07-01

Early development of cardiac hypertrophy may be beneficial but sustained hypertrophic activation leads to myocardial dysfunction. Regulation of the repolarizing currents can be modulated by the activation of humoral factors, such as angiotensin II (ANG II) through protein kinases. The aim of this work is to assess the regulation of IK and IK1 by ANG II through the PI3-K pathway in hypertrophied ventricular myocytes. Cardiac eccentric hypertrophy was induced through volume-overload in adult male rats by aorto-caval shunt (3 weeks). After one week half of the rats were given captopril (2 weeks; 0.5 g/l/day) and the other half served as control. The voltage-clamp and western blot techniques were used to measure the delayed outward rectifier potassium current (IK) and the instantaneous inward rectifier potassium current (IK1) and Akt activity, respectively. Hypertrophied cardiomyocytes showed reduction in IK and IK1. Treatment with captopril alleviated this difference seen between sham and shunt cardiomyocytes. Acute administration of ANG II (10-6M) to cardiocytes treated with captopril reduced IK and IK1 in shunts, but not in sham. Captopril treatment reversed ANG II effects on IK and IK1 in a PI3-K-independent manner. However in the absence of angiotensin converting enzyme inhibition, ANG II increased both IK and IK1 in a PI3-K-dependent manner in hypertrophied cardiomyocytes. Thus, captopril treatment reveals a negative effect of ANG II on IK and IK1, which is PI3-K independent, whereas in the absence of angiotensin converting enzyme inhibition IK and IK1 regulation is dependent upon PI3-K.

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

PubMed

Cho, Heesook; Yoo, Hana; Park, Soojin

2010-05-18

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

Method and apparatus for stable silicon dioxide layers on silicon grown in silicon nitride ambient

NASA Technical Reports Server (NTRS)

Cohen, R. A.; Wheeler, R. K. (Inventor)

1974-01-01

A method and apparatus for thermally growing stable silicon dioxide layers on silicon is disclosed. A previously etched and baked silicon nitride tube placed in a furnace is used to grow the silicon dioxide. First, pure oxygen is allowed to flow through the tube to initially coat the inside surface of the tube with a thin layer of silicon dioxide. After the tube is coated with the thin layer of silicon dioxide, the silicon is oxidized thermally in a normal fashion. If the tube becomes contaminated, the silicon dioxide is etched off thereby exposing clean silicon nitride and then the inside of the tube is recoated with silicon dioxide. As is disclosed, the silicon nitride tube can also be used as the ambient for the pyrolytic decomposition of silane and ammonia to form thin layers of clean silicon nitride.

Heat exchanger-ingot casting/slicing process, phase 1: Silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

NASA Technical Reports Server (NTRS)

Schmid, F.; Khattak, C. P.

1977-01-01

A controlled growth, heat-flow and cool-down process is described that yielded silicon with a high degree of single crystallinity. Even when the seed melted out, very large grains formed. Solar cell samples made from cast material yielded conversion efficiency of over 9%. Representative characterizations of grown silicon demonstrated a dislocation density of less than 100/sq cm and a minority carrier diffusion length of 31 micron. The source of silicon carbide in silicon ingots was identified to be from graphite retainers in contact with silica crucibles. Higher growth rates were achieved with the use of a graphite plug at the bottom of the silica crucible.

Custom 3D Printable Silicones with Tunable Stiffness.

PubMed

Durban, Matthew M; Lenhardt, Jeremy M; Wu, Amanda S; Small, Ward; Bryson, Taylor M; Perez-Perez, Lemuel; Nguyen, Du T; Gammon, Stuart; Smay, James E; Duoss, Eric B; Lewicki, James P; Wilson, Thomas S

2018-02-01

Silicone elastomers have broad versatility within a variety of potential advanced materials applications, such as soft robotics, biomedical devices, and metamaterials. A series of custom 3D printable silicone inks with tunable stiffness is developed, formulated, and characterized. The silicone inks exhibit excellent rheological behavior for 3D printing, as observed from the printing of porous structures with controlled architectures. Herein, the capability to tune the stiffness of printable silicone materials via careful control over the chemistry, network formation, and crosslink density of the ink formulations in order to overcome the challenging interplay between ink development, post-processing, material properties, and performance is demonstrated. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electron transport characteristics of silicon nanowires by metal-assisted chemical etching

NASA Astrophysics Data System (ADS)

Qi, Yangyang; Wang, Zhen; Zhang, Mingliang; Wang, Xiaodong; Ji, An; Yang, Fuhua

2014-03-01

The electron transport characteristics of silicon nanowires (SiNWs) fabricated by metal-assisted chemical etching with different doping concentrations were studied. By increasing the doping concentration of the starting Si wafer, the resulting SiNWs were prone to have a rough surface, which had important effects on the contact and the electron transport. A metal-semiconductor-metal model and a thermionic field emission theory were used to analyse the current-voltage (I-V) characteristics. Asymmetric, rectifying and symmetric I-V curves were obtained. The diversity of the I-V curves originated from the different barrier heights at the two sides of the SiNWs. For heavily doped SiNWs, the critical voltage was one order of magnitude larger than that of the lightly doped, and the resistance obtained by differentiating the I-V curves at large bias was also higher. These were attributed to the lower electron tunnelling possibility and higher contact barrier, due to the rough surface and the reduced doping concentration during the etching process.

Influence of Oxygen Deficiency on the Rectifying Behavior of Transparent-Semiconducting-Oxide-Metal Interfaces

NASA Astrophysics Data System (ADS)

Schultz, Thorsten; Vogt, Sofie; Schlupp, Peter; von Wenckstern, Holger; Koch, Norbert; Grundmann, Marius

2018-06-01

Transparent semiconducting oxides (TSO) are promising candidates for the fabrication of flexible and low-cost electronic devices, as they contain only abundant materials, are nontoxic, and exhibit high carrier mobilities. The formation of rectifying Schottky-barrier contacts is a prerequisite for devices, such as rectifiers, photodetectors, and metal-semiconductor field-effect transistors, and it was found that the presence of oxygen plays an essential role during the formation of the Schottky contacts. With electrical measurements on Pt/zinc-tin-oxide (ZTO) and PtOx/ZTO Schottky-barrier contacts and depth-resolved x-ray photoelectron spectroscopy measurements we demonstrate the important role of oxygen at the interface between TSOs and the metal contact for the rectifying behavior of diodes. In the vicinity of the interface, PtOx is reduced to Pt in a two-step process. Pt (OH) 4 is reduced within one day, whereas the reduction of PtO takes place over a time period of several weeks. The reduction results in improved rectification compared to Pt /ZTO , due to a filling of oxygen vacancies, which leads to a reduction of the free-carrier concentration in the vicinity of the PtOx/ZTO interface. This increases the depletion layer width and subsequently reduces the tunneling current, resulting in a higher rectification ratio. The time scale of the permanent performance improvement can be shortened significantly by applying a reverse bias to the diode. The described mechanism is most likely also present at other transparent-semiconducting-oxide-metal interfaces.

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

PubMed Central

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

2011-01-01

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

Influence of load type on power factor and harmonic composition of three-phase rectifier current

NASA Astrophysics Data System (ADS)

Nikolayzin, N. V.; Vstavskaya, E. V.; Konstantinov, V. I.; Konstantinova, O. V.

2018-05-01

This article is devoted to research of the harmonic composition of the three-phase rectifier current consumed when it operates with different types of load. The results are compared with Standard requirements.

Controlling the optical properties of monocrystalline 3C-SiC heteroepitaxially grown on silicon at low temperatures

NASA Astrophysics Data System (ADS)

Colston, Gerard; Myronov, Maksym

2017-11-01

Cubic silicon carbide (3C-SiC) offers an alternative wide bandgap semiconductor to conventional materials such as hexagonal silicon carbide (4H-SiC) or gallium nitride (GaN) for the detection of UV light and can offer a closely lattice matched virtual substrate for subsequent GaN heteroepitaxy. As 3C-SiC can be heteroepitaxially grown on silicon (Si) substrates its optical properties can be manipulated by controlling the thickness and doping concentrations. The optical properties of 3C-SiC epilayers have been characterized by measuring the transmission of light through suspended membranes. Decreasing the thickness of the 3C-SiC epilayers is shown to shift the absorbance edge to lower wavelengths, a result of the indirect bandgap nature of silicon carbide. This property, among others, can be exploited to fabricate very low-cost, tuneable 3C-SiC based UV photodetectors. This study investigates the effect of thickness and doping concentration on the optical properties of 3C-SiC epilayers grown at low temperatures by a standard Si based growth process. The results demonstrate the potential photonic applications of 3C-SiC and its heterogeneous integration into the Si industry.

Effect of argon implantation on solid-state dewetting: control of size and surface density of silicon nanocrystals.

PubMed

Almadori, Y; Borowik, Ł; Chevalier, N; Barbé, J-C

2017-01-27

Thermally induced solid-state dewetting of ultra-thin films on insulators is a process of prime interest, since it is capable of easily forming nanocrystals. If no particular treatment is performed to the film prior to the solid-state dewetting, it is already known that the size, the shape and the density of nanocrystals is governed by the initial film thickness. In this paper, we report a novel approach to control the size and the surface density of silicon nanocrystals based on an argon-implantation preliminary surface treatment. Using 7.5 nm thin layers of silicon, we show that increasing the implantation dose tends to form smaller silicon nanocrystals with diameter and height lower than 50 nm and 30 nm, respectively. Concomitantly, the surface density is increased by a factor greater than 20, going from 5 μm -2 to values over 100 μm -2 .

Antifuse with a single silicon-rich silicon nitride insulating layer

DOEpatents

Habermehl, Scott D.; Apodaca, Roger T.

2013-01-22

An antifuse is disclosed which has an electrically-insulating region sandwiched between two electrodes. The electrically-insulating region has a single layer of a non-hydrogenated silicon-rich (i.e. non-stoichiometric) silicon nitride SiN.sub.X with a nitrogen content X which is generally in the range of 0controlling the composition and thickness of the SiN.sub.X layer. The SiN.sub.X layer thickness can also be made sufficiently large so that Poole-Frenkel emission will be the primary electrical conduction mechanism in the antifuse. Different types of electrodes are disclosed including electrodes formed of titanium silicide, aluminum and silicon. Arrays of antifuses can also be formed.

Endoscopic dacryocystorhinostomy with silicone, polypropylene, and T-tube stents; randomized controlled trial of efficacy and safety.

PubMed

Okuyucu, Semsettin; Gorur, Hatice; Oksuz, Huseyin; Akoglu, Ertap

2015-01-01

To compare the efficacy and safety of endoscopic dacryocystorhinostomy (En-DCR) with different stent materials for lacrimal sac intubation in primary nasolacrimal ductal obstructions. Randomized controlled study with three parallel groups. Level of evidence is 1b. A total of 91 patients (five bilateral) with primary nasolacrimal duct obstruction (NLDO) at a tertiary referral center scheduled for En-DCR were to allocated into three stent groups with a sealed envelope and were randomized into three treatments: silicone, Prolene (polypropylene), and otologic T-tube. Ophthalmology and otolaryngology clinics evaluated the patients preoperatively and postoperatively with endoscopes, lacrimal system syringing, and dacryocystography. The success of the stents was evaluated 12 months after surgery with symptom relief and ostial patency. Complications were also noted. The overall success rate of the En-DCR in the stent groups was 78.1% (75/96); specifically, 87.5% (28/32) with silicone, 84.4% (27/32) with Prolene, and 62.5% (20/32) with T-tube. The efficacy of the procedures with the T-tube was significantly lower than that of the Prolene and silicone (p = .031, χ(2) test). There were no significant differences between the silicone and Prolene (p = .718, χ(2) test). Prolene was found to be related with orbital complications. Spontaneous loss is a particular complication of otologic T-tube and highly portends to failure. The results of our study suggest that efficacy, defined as anatomic and functional success, is equally high for silicone and Prolene stents and lower for otologic T-tube in En-DCR.

A New Class III Antiarrhythmic Drug Niferidil Prolongs Action Potentials in Guinea Pig Atrial Myocardium via Inhibition of Rapid Delayed Rectifier.

PubMed

Abramochkin, Denis V; Kuzmin, Vladislav S; Rosenshtraukh, Leonid V

2017-12-01

A new class III antiarrhythmic drug niferidil (RG-2) has been introduced as a highly effective therapy for cases of persistent atrial fibrillation, but ionic mechanisms of its action are poorly understood. In the present study, the effects of niferidil on action potential (AP) waveform and potassium currents responsible for AP repolarization were investigated in guinea pig atrial myocardium. APs were recorded with sharp glass microelectrodes in multicellular atrial preparations. Whole-cell patch-clamp technique was used to measure K + currents in isolated myocytes. In multicellular atrial preparations, 10 -8  M niferidil effectively prolonged APs by 15.2 ± 2.8% at 90% repolarization level. However, even the highest tested concentrations, 10 -6  M and 10 -5  M failed to prolong APs more than 32.5% of control duration. The estimated concentration of niferedil for half-maximal AP prolongation was 1.13 × 10 -8  M. Among the potassium currents responsible for AP repolarization phase, I K1 was found to be almost insensitive to niferidil. However, another inward rectifier, I KACh , was effectively suppressed by micromolar concentrations of niferidil with IC 50  = 9.2 × 10 -6  M. I KATP was much less sensitive to the drug with IC 50  = 2.26 × 10 -4  M. The slow component of delayed rectifier, I Ks , also demonstrated low sensitivity to niferidil-the highest used concentration, 10 -4  M, decreased peak I Ks density to 46.2 ± 5.5% of control. Unlike I Ks , the rapid component of delayed rectifier, I Kr , appeared to be extremely sensitive to niferidil. The IC 50 was 1.26 × 10 -9  M. I Kr measured in ventricular myocytes was found to be less sensitive to niferidil with IC 50  = 3.82 × 10 -8  M. Niferidil prolongs APs in guinea pig atrial myocardium via inhibition of I Kr .

Optoelectrical Properties of a Heterojunction with Amorphous InGaZnO Film on n-Silicon Substrate

NASA Astrophysics Data System (ADS)

Jiang, D. L.; Ma, X. Z.; Li, L.; Xu, Z. K.

2017-10-01

An a-IGZO/ n-Si heterojunction device has been fabricated at room temperature by depositing amorphous InGaZnO (a-IGZO) film on n-type silicon substrate by plasma-assisted pulsed laser deposition and its optoelectrical properties studied in detail. The heterojunction showed distinct rectifying characteristic with rectification ratio of 1.93 × 103 at ±2 V bias and reverse leakage current density of 1.6 × 10-6 A cm-2 at -2 V bias. More interestingly, the heterojunction not only showed the characteristic of unbiased photoresponse, but could also detect either ultraviolet or ultraviolet-visible light by simply changing the polarity of the bias applied to the heterojunction. The variable photoresponse phenomenon and the charge transport mechanisms in the heterojunction are explained based on the energy band diagram of the heterojunction.

Rectified motion in an asymmetrically structured channel due to induced-charge electrokinetic and thermo-kinetic phenomena

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

Sugioka, Hideyuki, E-mail: hsugioka@shinshu-u.ac.jp

2016-02-15

It would be advantageous to move fluid by the gradient of random thermal noises that are omnipresent in the natural world. To achieve this motion, we propose a rectifier that uses a thermal noise along with induced-charge electroosmosis and electrophoresis (ICEO and ICEP) around a metal post cylinder in an asymmetrically structured channel and numerically examine its rectification performance. By the boundary element method combined with the thin double layer approximation, we find that rectified motion occurs in the asymmetrically structured channel due to ICEO and ICEP. Further, by thermodynamical and equivalent circuit methods, we discuss a thermal voltage thatmore » drives a rectifier consisting of a fluidic channel of an electrolyte and an impedance as a noise source. Our calculations show that fluid can be moved in the asymmetrically structured channel by the fluctuation of electric fields due to a thermal noise only when there is a temperature difference. In addition, our simple noise argument provides a different perspective for the thermo-kinetic phenomena (around a metal post) which was predicted based on the electrolyte Seebeck effect in our previous paper [H. Sugioka, “Nonlinear thermokinetic phenomena due to the Seebeck effect,” Langmuir 30, 8621 (2014)].« less

Encapsulation and controlled release of retinol from silicone particles for topical delivery.

PubMed

Shields, C Wyatt; White, John P; Osta, Erica G; Patel, Jerishma; Rajkumar, Shashank; Kirby, Nickolas; Therrien, Jean-Philippe; Zauscher, Stefan

2018-05-28

Retinol, a derivative of vitamin A, is a ubiquitous compound used to treat acne, reduce wrinkles and protect against conditions like psoriasis and ichthyosis. While retinol is used as the primary active ingredient (AI) in many skin care formulations, its efficacy is often limited by an extreme sensitivity to degrade and toxicity at high concentrations. While microencapsulation is an appealing method to help overcome these issues, few microencapsulation strategies have made a major translational impact due to challenges with complexity, cost, limited protection of the AI and poor control of the release of the AI. We have developed a class of silicone particles that addresses these challenges for the encapsulation, protection and controlled release of retinol and other hydrophobic compounds. The particles are prepared by the sol-gel polymerization of silane monomers, which enables their rapid and facile synthesis at scale while maintaining a narrow size distribution (i.e., CV < 20%). We show that our particles can: (i) encapsulate retinol with high efficiency (>85%), (ii) protect retinol from degradation (yielding a half-life 9× greater than unencapsulated retinol) and (iii) slowly release retinol over several hours (at rates from 0.14 to 0.67 μg cm -2  s -1/2 ). To demonstrate that the controlled release of retinol from the particles can reduce irritation, we performed a double blind study on human subjects and found that formulations containing our particles were 12-23% less irritating than identical formulations containing Microsponge® particles (an industry standard by Amcol, Inc.). To show that the silicone particles can elicit a favorable biological response, similar to the Microsponge® particles, we applied both formulations to reconstructed human epidermal tissues and found an upregulation of keratin 19 (K19) and a downregulation of K10, indicating that the reduced irritation observed in the human study was not caused by reduced activity. We

Silicone Polymer Composites for Thermal Protection System: Fiber Reinforcements and Microstructures

DTIC Science & Technology

2010-01-01

angles were tested. Detailed microstructural, mass loss, and peak erosion analyses were conducted on the phenolic -based matrix composite (control) and...silicone-based matrix composites to understand their protective mechanisms. Keywords silicone polymer matrix composites, phenolic polymer matrix...erosion analyses were conducted on the phenolic -based matrix composite (control) and silicone-based matrix composites to understand their protective

G-protein mediated gating of inward-rectifier K+ channels.

PubMed

Mark, M D; Herlitze, S

2000-10-01

G-protein regulated inward-rectifier potassium channels (GIRK) are part of a superfamily of inward-rectifier K+ channels which includes seven family members. To date four GIRK subunits, designated GIRK1-4 (also designated Kir3.1-4), have been identified in mammals, and GIRK5 has been found in Xenopus oocytes. GIRK channels exist in vivo both as homotetramers and heterotetramers. In contrast to the other mammalian GIRK family members, GIRK1 can not form functional channels by itself and has to assemble with GIRK2, 3 or 4. As the name implies, GIRK channels are modulated by G-proteins; they are also modulated by phosphatidylinositol 4,5-bisphosphate, intracellular sodium, ethanol and mechanical stretch. Recently a family of GTPase activating proteins known as regulators of G-protein signaling were shown to be the missing link for the fast deactivation kinetics of GIRK channels in native cells, which contrast with the slow kinetics observed in heterologously expressed channels. GIRK1, 2 and 3 are highly abundant in brain, while GIRK4 has limited distribution. Here, GIRK1/2 seems to be the predominant heterotetramer. In general, neuronal GIRK channels are involved in the regulation of the excitability of neurons and may contribute to the resting potential. Interestingly, only the GIRK1 and 4 subunits are distributed in the atrial and sinoatrial node cells of the heart and are involved in the regulation of cardiac rate. Our main objective of this review is to assess the current understanding of the G-protein modulation of GIRK channels and their physiological importance in mammals.

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

PubMed

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

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.

Combining points and lines in rectifying satellite images

NASA Astrophysics Data System (ADS)

Elaksher, Ahmed F.

2017-09-01

The quick advance in remote sensing technologies established the potential to gather accurate and reliable information about the Earth surface using high resolution satellite images. Remote sensing satellite images of less than one-meter pixel size are currently used in large-scale mapping. Rigorous photogrammetric equations are usually used to describe the relationship between the image coordinates and ground coordinates. These equations require the knowledge of the exterior and interior orientation parameters of the image that might not be available. On the other hand, the parallel projection transformation could be used to represent the mathematical relationship between the image-space and objectspace coordinate systems and provides the required accuracy for large-scale mapping using fewer ground control features. This article investigates the differences between point-based and line-based parallel projection transformation models in rectifying satellite images with different resolutions. The point-based parallel projection transformation model and its extended form are presented and the corresponding line-based forms are developed. Results showed that the RMS computed using the point- or line-based transformation models are equivalent and satisfy the requirement for large-scale mapping. The differences between the transformation parameters computed using the point- and line-based transformation models are insignificant. The results showed high correlation between the differences in the ground elevation and the RMS.

Efficacy of the Power Balance Silicone Wristband: a single-blind, randomized, triple placebo-controlled study.

PubMed

Pothier, David D; Thiel, Gundula; Khoo, S G; Dillon, Wanda A; Sulway, Shaleen; Rutka, John A

2012-06-01

The Power Balance Silicone Wristband (Power Balance LLC, Laguna Niguel, CA) (power balance band; PBB) consists of a silicone wristband, incorporating two holograms, which is meant to confer improvements in balance on the wearer. Despite its popularity, the PBB has become somewhat controversial, with a number of articles being published in the news media regarding its efficacy. The PBB has not been formally evaluated but remains popular, largely based on anecdotal evidence. This study subjectively and objectively measured the effects of the PBB on balance in normal participants. A prospective, single-blind, randomized, triple placebo-controlled crossover study was undertaken. Twenty participants underwent measurement using the modified Test of Sensory Interaction on Balance (mCTSIB) and gave subjective feedback (visual analogue scale [VAS]) for each of four band conditions: no band, a silicone band, a deactivated PBB, and the PBB. Participants acted as their own controls. The mean of the four mCTSIB conditions (eyes open and closed on both firm and compliant surfaces) was calculated. This mean value and condition 4 of the mCTSIB were compared between band conditions using path length (PL) and root mean square (RMS) as outcome measures. No significant differences were found between band conditions for PL (p  =  .91 and p  =  .94, respectively) and RMS (p  =  .85 and p  =  .96, respectively). VASs also showed no difference between bands (p  =  .25). The PBB appears to have no effect on mCTSIB or VAS measurements of balance.

Hybrid Photon-Plasmon Coupling and Ultrafast Control of Nanoantennas on a Silicon Photonic Chip.

PubMed

Chen, Bigeng; Bruck, Roman; Traviss, Daniel; Khokhar, Ali Z; Reynolds, Scott; Thomson, David J; Mashanovich, Goran Z; Reed, Graham T; Muskens, Otto L

2018-01-10

Hybrid integration of nanoplasmonic devices with silicon photonic circuits holds promise for a range of applications in on-chip sensing, field-enhanced and nonlinear spectroscopy, and integrated nanophotonic switches. Here, we demonstrate a new regime of photon-plasmon coupling by combining a silicon photonic resonator with plasmonic nanoantennas. Using principles from coherent perfect absorption, we make use of standing-wave light fields to maximize the photon-plasmon interaction strength. Precise placement of the broadband antennas with respect to the narrowband photonic racetrack modes results in controlled hybridization of only a subset of these modes. By combining antennas into groups of radiating dipoles with opposite phase, far-field scattering is effectively suppressed. We achieve ultrafast tuning of photon-plasmon hybridization including reconfigurable routing of the standing-wave input between two output ports. Hybrid photonic-plasmonic resonators provide conceptually new approaches for on-chip integrated nanophotonic devices.

Children Rectify Inequalities for Disadvantaged Groups

PubMed Central

Elenbaas, Laura; Killen, Melanie

2016-01-01

Children’s decisions regarding the allocation of societal resources in the context of preexisting inequalities were investigated. African-American and European-American children ages 5–6 years (n = 91) and 10–11 years (n = 94) judged the acceptability of a medical resource inequality on the basis of race, allocated medical supplies, evaluated different resource allocation strategies, and completed a measure of status awareness based on race. With age, children were increasingly aware of wealth status disparities between African-Americans and European-Americans, and judged a medical resource inequality between groups more negatively. Further, with age, children rectified the resource inequality over perpetuating it, but only when African-American children were disadvantaged. With age, children also referenced rights when reasoning about their judgments concerning the disadvantaged African-American group. When European-American children were disadvantaged, children did not systematically allocate more resources to one group over another. The results are discussed in terms of social inequalities, disadvantaged status, moral judgments, and intergroup attitudes. PMID:27455190

Inhibitory Effect of Vascular Endothelial Growth Factor on the Slowly Activating Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytes.

PubMed

Lin, Zhenhao; Xing, Wenlu; Gao, Chuanyu; Wang, Xianpei; Qi, Datun; Dai, Guoyou; Zhao, Wen; Yan, Ganxin

2018-01-26

Vascular endothelial growth factor (VEGF) exerts a number of beneficial effects on ischemic myocardium via its angiogenic properties. However, little is known about whether VEGF has a direct effect on the electrical properties of cardiomyocytes. In the present study, we investigated the effects of different concentrations of VEGF on delayed rectifier potassium currents (I K ) in guinea pig ventricular myocytes and their effects on action potential (AP) parameters. I K and AP were recorded by the whole-cell patch clamp method in ventricular myocytes. Cells were superfused with control solution or solution containing VEGF at different concentrations for 10 minutes before recording. Some ventricular myocytes were pretreated with a phosphatidylinositol 3-kinase inhibitor for 1 hour before the addition of VEGF. We found that VEGF inhibited the slowly activating delayed rectifier potassium current (I K s ) in a concentration-dependent manner (18.13±1.04 versus 12.73±0.34, n=5, P =0.001; 12.73±0.34 versus 9.05±1.20, n=5, P =0.036) and prolonged AP duration (894.5±36.92 versus 746.3±33.71, n=5, P =0.021). Wortmannin, a phosphatidylinositol 3-kinase inhibitor, eliminated these VEGF-induced effects. VEGF had no significant effect on the rapidly activating delayed rectifier potassium current (I K r ), resting membrane potential, AP amplitude, or maximal velocity of depolarization. VEGF inhibited I K s in a concentration-dependent manner through a phosphatidylinositol 3-kinase-mediated signaling pathway, leading to AP prolongation. The results indicate a promising therapeutic potential of VEGF in prevention of ventricular tachyarrhythmias under conditions of high sympathetic activity and ischemia. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Silicon surface passivation by silicon nitride deposition

NASA Technical Reports Server (NTRS)

Olsen, L. C.

1984-01-01

Silicon nitride deposition was studied as a method of passivation for silicon solar cell surfaces. The following three objectives were the thrust of the research: (1) the use of pecvd silicon nitride for passivation of silicon surfaces; (2) measurement techniques for surface recombination velocity; and (3) the importance of surface passivation to high efficiency solar cells.

Silicon carbide, an emerging high temperature semiconductor

NASA Technical Reports Server (NTRS)

Matus, Lawrence G.; Powell, J. Anthony

1991-01-01

In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

Electrically Conductive and Optically Active Porous Silicon Nanowires

PubMed Central

Qu, Yongquan; Liao, Lei; Li, Yujing; Zhang, Hua; Huang, Yu; Duan, Xiangfeng

2009-01-01

We report the synthesis of vertical silicon nanowire array through a two-step metal-assisted chemical etching of highly doped n-type silicon (100) wafers in a solution of hydrofluoric acid and hydrogen peroxide. The morphology of the as-grown silicon nanowires is tunable from solid nonporous nanowires, nonporous/nanoporous core/shell nanowires, and entirely nanoporous nanowires by controlling the hydrogen peroxide concentration in the etching solution. The porous silicon nanowires retain the single crystalline structure and crystallographic orientation of the starting silicon wafer, and are electrically conductive and optically active with visible photoluminescence. The combination of electronic and optical properties in the porous silicon nanowires may provide a platform for the novel optoelectronic devices for energy harvesting, conversion and biosensing. PMID:19807130

Low cost solar array project 1: Silicon material

NASA Technical Reports Server (NTRS)

Jewett, D. N.; Bates, H. E.; Hill, D. M.

1980-01-01

The low cost production of silicon by deposition of silicon from a hydrogen/chlorosilane mixture is described. Reactor design, reaction vessel support systems (physical support, power control and heaters, and temperature monitoring systems) and operation of the system are reviewed. Testing of four silicon deposition reactors is described, and test data and consequently derived data are given. An 18% conversion of trichlorosilane to silicon was achieved, but average conversion rates were lower than predicted due to incomplete removal of byproduct gases for recycling and silicon oxide/silicon polymer plugging of the gas outlet. Increasing the number of baffles inside the reaction vessel improved the conversion rate. Plans for further design and process improvements to correct the problems encountered are outlined.

Pharmacological modulations of cardiac ultra-rapid and slowly activating delayed rectifier currents: potential antiarrhythmic approaches.

PubMed

Islam, Mohammed A

2010-01-01

Despite the emerging new insights into our understandings of the cellular mechanisms underlying cardiac arrhythmia, medical therapy for this disease remains unsatisfactory. Atrial fibrillation (AF), the most prevalent arrhythmia, is responsible for significant morbidity and mortality. On the other hand, ventricular fibrillation results in sudden cardiac deaths in many instances. Prolongation of cardiac action potential (AP) is a proven principle of antiarrhythmic therapy. Class III antiarrhythmic agents prolong AP and QT interval by blocking rapidly activating delayed rectifier current (I(Kr)). However, I(Kr) blocking drugs carry the risk of life-threatening proarrhythmia. Recently, modulation of atrial-selective ultra-rapid delayed rectifier current (I(Kur)), has emerged as a novel therapeutic approach to treat AF. A number of I(Kur) blockers are being evaluated for the treatment of AF. The inhibition of slowly activating delayed rectifier current (I(Ks)) has also been proposed as an effective and safer antiarrhythmic approach because of its distinguishing characteristics that differ in remarkable ways from other selective class III agents. Selective I(Ks) block may prolong AP duration (APD) at rapid rates without leading to proarrhythmia. This article reviews the pathophysiological roles of I(Kur) and I(Ks) in cardiac repolarization and the implications of newly developed I(Kur) and I(Ks) blocking agents as promising antiarrhythmic approaches. Several recent patents pertinent to antiarrhythmic drug development have been discussed. Further research will be required to evaluate the efficacy and safety of these agents in the clinical setting.

Asymmetric Die Grows Purer Silicon Ribbon

NASA Technical Reports Server (NTRS)

Kalejs, J. P.; Chalmers, B.; Surek, T.

1983-01-01

Concentration of carbide impurities in silicon ribbon is reduced by growing crystalline ribbon with die one wall higher than other. Height difference controls shape of meniscus at liquid/crystal interface and concentrates silicon carbide impurity near one of broad faces. Opposite face is left with above-average purity. Significantly improves efficiency of solar cells made from ribbon.

Dexamethasone implant in silicone oil: in vitro behavior.

PubMed

Flores-Villalobos, Erick Omar; Ramírez-Estudillo, J Abel; Robles-Contreras, Atzin; Oliva-Ramírez, Jacqueline L

2018-01-01

To determine the effect of the silicone on the dexamethasone intravitreal implant. Basic, experimental, prospective and transversal study performed at the hospital "Nuestra Señora de la Luz" in Mexico City. One dexamethasone implant was placed in a test tube with 4 mL of each tamponade medium: 1000cS, 5000cS and heavy silicone oil; basic saline solution was used as the control medium. Photographs were taken weekly for 12 months. 200 µL samples were taken from each medium at 24 h, 1, 2 weeks and monthly for 12 months. ELISA test was performed to quantify dexamethasone release in every sample. An inflammatory stimulus was created and later exposed it to every sample in order to test their anti-inflammatory capacity by cytokine analysis using cytometric bead array. Statistically significant results were obtained with p < 0.05. Photographic follow-up showed disintegration of the implant in control medium. Implants in silicone oil suffered no changes during follow-up. Dexamethasone levels in control medium showed stability from month 2 to 12. Silicone oil mediums showed irregular dexamethasone release during the 1 year period. Dexamethasone in control medium had inhibitory effects on TNF-α starting at 24 h (p < 0.001) and remained stable. Dexamethasone in 1000cS silicone oil showed inhibitory effects from month 2 (p < 0.001) until month 6 (p < 0.001). Implants in denser silicone oils showed no inhibitory effects in any of the samples. Denser mediums altered the implant pharmacokinetics and showed no anti-inflammatory effects even when concentrations were quantified at levels similar to control medium in vitro.

Total-dose radiation effects data for semiconductor devices, volume 1. [radiation resistance of components for the Galileo Project

NASA Technical Reports Server (NTRS)

Price, W. E.; Martin, K. E.; Nichols, D. K.; Gauthier, M. K.; Brown, S. F.

1981-01-01

Steady-state, total-dose radiation test data are provided in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. Data are presented by JPL for various NASA space programs on diodes, bipolar transistors, field effect transistors, silicon-controlled rectifiers, and optical devices. A vendor identification code list is included along with semiconductor device electrical parameter symbols and abbreviations.

An isolated bridgeless AC-DC PFC converter using a LC resonant voltage doubler rectifier

NASA Astrophysics Data System (ADS)

Lee, Sin-woo; Do, Hyun-Lark

2016-12-01

This paper proposed an isolated bridgeless AC-DC power factor correction (PFC) converter using a LC resonant voltage doubler rectifier. The proposed converter is based on isolated conventional single-ended primary inductance converter (SEPIC) PFC converter. The conduction loss of rectification is reduced than a conventional one because the proposed converter is designed to eliminate a full-bridge rectifier at an input stage. Moreover, for zero-current switching (ZCS) operation and low voltage stresses of output diodes, the secondary of the proposed converter is designed as voltage doubler with a LC resonant tank. Additionally, an input-output electrical isolation is provided for safety standard. In conclusion, high power factor is achieved and efficiency is improved. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 60 W prototype at a constant switching frequency 100 kHz are presented to verify the performance of the proposed converter.

Antidromic-rectifying gap junctions amplify chemical transmission at functionally mixed electrical-chemical synapses

PubMed Central

Liu, Ping; Chen, Bojun; Mailler, Roger; Wang, Zhao-Wen

2017-01-01

Neurons communicate through chemical synapses and electrical synapses (gap junctions). Although these two types of synapses often coexist between neurons, little is known about whether they interact, and whether any interactions between them are important to controlling synaptic strength and circuit functions. By studying chemical and electrical synapses between premotor interneurons (AVA) and downstream motor neurons (A-MNs) in the Caenorhabditis elegans escape circuit, we found that disrupting either the chemical or electrical synapses causes defective escape response. Gap junctions between AVA and A-MNs only allow antidromic current, but, curiously, disrupting them inhibits chemical transmission. In contrast, disrupting chemical synapses has no effect on the electrical coupling. These results demonstrate that gap junctions may serve as an amplifier of chemical transmission between neurons with both electrical and chemical synapses. The use of antidromic-rectifying gap junctions to amplify chemical transmission is potentially a conserved mechanism in circuit functions. PMID:28317880

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

PubMed

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

2007-08-01

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

Method for producing silicon nitride/silicon carbide composite

DOEpatents

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

1996-07-23

Silicon carbide/silicon nitride composites are prepared by carbothermal reduction of crystalline silica powder, carbon powder and optionally crsytalline silicon nitride powder. The crystalline silicon carbide portion of the composite has a mean number diameter less than about 700 nanometers and contains nitrogen.

Composite silicon nanostructure arrays fabricated on optical fibre by chemical etching of multicrystal silicon film.

PubMed

Zuo, Zewen; Zhu, Kai; Ning, Lixin; Cui, Guanglei; Qu, Jun; Huang, Wanxia; Shi, Yi; Liu, Hong

2015-04-17

Integrating nanostructures onto optical fibers presents a promising strategy for developing new-fashioned devices and extending the scope of nanodevices' applications. Here we report the first fabrication of a composite silicon nanostructure on an optical fiber. Through direct chemical etching using an H2O2/HF solution, multicrystal silicon films with columnar microstructures are etched into a vertically aligned, inverted-cone-like nanorod array embedded in a nanocone array. A faster dissolution rate of the silicon at the void-rich boundary regions between the columns is found to be responsible for the separation of the columns, and thus the formation of the nanostructure array. The morphology of the nanorods primarily depends on the microstructure of the columns in the film. Through controlling the microstructure of the as-grown film and the etching parameters, the structural control of the nanostructure is promising. This fabrication method can be extended to a larger length scale, and it even allows roll-to-roll processing.

Doping of silicon by carbon during laser ablation process

NASA Astrophysics Data System (ADS)

Raciukaitis, G.; Brikas, M.; Kazlauskiene, V.; Miskinis, J.

2007-04-01

Effect of laser ablation on properties of remaining material was investigated in silicon. It was established that laser cutting of wafers in air induced doping of silicon by carbon. The effect was found to be more distinct by the use of higher laser power or UV radiation. Carbon ions created bonds with silicon in the depth of silicon. Formation of the silicon carbide type bonds was confirmed by SIMS, XPS and AES measurements. Modeling of the carbon diffusion was performed to clarify its depth profile in silicon. Photo-chemical reactions of such type changed the structure of material and could be a reason for the reduced quality of machining. A controlled atmosphere was applied to prevent carbonization of silicon during laser cutting.

Silicone metalization

DOEpatents

Maghribi, Mariam N [Livermore, CA; Krulevitch, Peter [Pleasanton, CA; Hamilton, Julie [Tracy, CA

2006-12-05

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

Silicone metalization

DOEpatents

Maghribi, Mariam N.; Krulevitch, Peter; Hamilton, Julie

2008-12-09

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

Iodine 125 Brachytherapy With Vitrectomy and Silicone Oil in the Treatment of Uveal Melanoma: 1-to-1 Matched Case-Control Series

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

McCannel, Tara A., E-mail: TMcCannel@jsei.ucla.edu; McCannel, Colin A.

Purpose: We initially reported the radiation-attenuating effect of silicone oil 1000 centistokes for iodine 125. The purpose of this report was to compare the clinical outcomes in case patients who had iodine 125 brachytherapy with vitrectomy and silicone oil 1000 centistokes with the outcomes in matched control patients who underwent brachytherapy alone. Methods and Materials: Consecutive patients with uveal melanoma who were treated with iodine 125 plaque brachytherapy and vitrectomy with silicone oil with minimum 1-year follow-up were included. Control patients who underwent brachytherapy alone were matched for tumor size, location, and sex. Baseline patient and tumor characteristics and tumor response tomore » radiation, final visual acuity, macular status, central macular thickness by ocular coherence tomography (OCT), cataract progression, and metastasis at last follow-up visit were compared. Surgical complications were also determined. Results: Twenty case patients met the inclusion criteria. The average follow-up time was 22.1 months in case patients and 19.4 months in control patients. The final logMAR vision was 0.81 in case patients and 1.1 in control patients (P=.071); 8 case patients and 16 control patients had abnormal macular findings (P=.011); and the average central macular thickness by OCT was 293.2 μm in case patients and 408.5 μm in control patients (P=.016). Eleven case patients (55%) and 1 control patient (5%) had required cataract surgery at last follow-up (P=.002). Four patients in the case group and 1 patient in the control group experienced metastasis (P=.18). Among the cases, intraoperative retinal tear occurred in 3 patients; total serous retinal detachment and macular hole developed in 1 case patient each. There was no case of rhegmatogenous retinal detachment, treatment failure, or local tumor dissemination in case patients or control patients. Conclusions: With up to 3 years of clinical follow-up, silicone oil during

Controlling the shapes of coated silicon substrates via magnetic fields, a progress report

NASA Astrophysics Data System (ADS)

Ulmer, Melville P.; Coppejans, Rocco; Buchholz, David B.; Cao, Jian; Wang, Xiaoli; Mercado, Alejandro M.; Qian, Jun; Assoufid, Lahsen; O'Donnell, Allison E.; Condron, Kyle S.; Harpt, Benjamin E.

2017-08-01

We describe our progress in developing a method for correcting residual figure errors in X-ray mirrors. The technology has applications to both synchrotron radiation beamlines and X-ray astronomy. Our concept is to develop mirrors that are on the order of a millimeter thick. A magnetic smart material (MSM) is deposited onto the mirror substrate (silicon) and coated with a magnetically hard material. The shape of the mirror can be controlled by applying an external magnetic field to the mirror. This causes the MSM to expand or contract, thereby applying a magnetostrictive stress to the mirror and changing its shape. The shape change is maintained after the field has been removed by the magnetic hard material, which retains part of the field and prevents the MSM from relaxing. Here we present the results of shaping 200 µm thick silicon (100) 14 × 2 mm cantilevers and 50 × 50 × 0.1 mm substrates. We demonstrate that not only can a sizable deflection be created, but it can also be retained for ˜ 60 hours.

Growing Cobalt Silicide Columns In Silicon

NASA Technical Reports Server (NTRS)

Fathauer, Obert W.

1991-01-01

Codeposition by molecular-beam epitaxy yields variety of structures. Proposed fabrication process produces three-dimensional nanometer-sized structures on silicon wafers. Enables control of dimensions of metal and semiconductor epitaxial layers in three dimensions instead of usual single dimension (perpendicular to the plane of the substrate). Process used to make arrays of highly efficient infrared sensors, high-speed transistors, and quantum wires. For fabrication of electronic devices, both shapes and locations of columns controlled. One possible technique for doing this electron-beam lithography, see "Making Submicron CoSi2 Structures on Silicon Substrates" (NPO-17736).

Enterovaginal or Vesicovaginal Fistula Control Using a Silicone Cup.

PubMed

Russell, Katie W; Robinson, Ryan E; Mone, Mary C; Scaife, Courtney L

2016-12-01

An enterovaginal or vesicovaginal fistula is a complication resulting in vaginal discharge of succus, urine, or stool that can lead to significant complications. For low-volume fistulae, tampons or pads may be used. With high-volume fistulae, frequent product change can be painful and unpredictable in terms of efficacy. The psychologic distress is profound. Surgery may not be an option, making symptom control the priority. We report the use of a reusable menstrual silicone vaginal cup placed to divert and contain drainage. The menstrual cup provided significant symptom relief. Drainage is immediately diverted from tissue, unlike with tampon or pad use, which involves longer contact periods with caustic fluids. A system was created by adapting the end of the cup by adding silastic tubing and an external leg bag to provide long-term drainage control. Improvement in quality of life is of primary importance when dealing with fistula drainage. This simple and inexpensive device should be considered in those cases in which the drainage can be diverted as a viable option, especially in those who are symptomatic and awaiting surgical repair or in those for whom surgery cannot be performed.

Study on control of defect mode in hybrid mirror chirped porous silicon photonic crystal

NASA Astrophysics Data System (ADS)

Chen, Ying; Luo, Pei; Han, Yangyang; Cui, Xingning; He, Lei

2018-03-01

Based on the optical resonance principle and the tight-binding theory, a hybrid mirror chirped porous silicon photonic crystal is proposed. The control of the defect mode in hybrid mirror chirped porous silicon photonic crystal is studied. Through the numerical simulation, the control regulations of the defect modes resulted by the number of the periodical layers for the fundamental unit and the cascading number of the chirped structures are analyzed, and the split and the degeneration of the defect modes resulted by the change of the relative location between the mirror structures and the quasi-mirror structures are discussed. The simulation results show that the band gap would be broadened with the increase of the chirp quantity and the layer number of unilateral chirp. Adjusting the structural parameters of the hybrid mirror structure, the multimode characteristics will occur in the band gap. The more the cascading number of the chirped units, the more the number of the filtering channels will be. In addition, with the increase of the relative location between the mirror structures and the quasi-mirror structures, the degeneration of the defect modes will occur and can obtain high Q value. The structure can provide effective theoretical references for the design the multi-channel filters and high Q value sensors.

Thiolated silicone oils as adhesive skin protectants for improved barrier function.

PubMed

Partenhauser, A; Zupančič, O; Rohrer, J; Bonengel, S; Bernkop-Schnürch, A

2016-06-01

The purpose of this study was the evaluation of thiolated silicone oil as novel skin protectant exhibiting prolonged residence time, enhanced barrier function and reinforced occlusivity. Two silicone conjugates were synthesized with mercaptopropionic acid (MPA) and thioglycolic acid (TGA) as thiol ligands. Adhesion, protection against artificial urine and water vapour permeability with both a Payne cup set-up and transepidermal water loss (TEWL) measurements on porcine skin were assessed. Silicone thiomers showed pronounced substantivity on skin with 22.1 ± 6.3% and 39.2 ± 6.7% remaining silicone after 8 h for silicone-TGA and silicone-MPA, respectively, whereas unmodified silicone oil and dimethicone were no longer detectable. In particular, silicone-MPA provided a protective shield against artificial urine penetration with less than 25% leakage within 6 h. An up to 2.5-fold improved water vapour impermeability for silicone-MPA in comparison with unmodified control was discovered with the Payne cup model. In addition, for silicone-MPA a reduced TEWL by two-thirds corresponding to non-thiolated control was determined for up to 8 h. Thiolation of silicone oil leads to enhanced skin adhesiveness and barrier function, which is a major advantage compared to commonly used silicones and might thus be a promising treatment modality for various topical applications. © 2015 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Silicon microring resonators

NASA Astrophysics Data System (ADS)

Tan, Ying; Dai, Daoxin

2018-05-01

Silicon microring resonators (MRRs) are very popular for many applications because of the advantages of footprint compactness, easy scalability, and functional versatility. Ultra-compact silicon MRRs with box-like spectral responses are realized with a very large free-spectral range (FSR) by introducing bent directional couplers. The measured box-like spectral response has an FSR of >30 nm. The permanent wavelength-alignment techniques for MRRs are also presented, including the laser-induced local-oxidation technique as well as the local-etching technique. With these techniques, one can control finely the permanent wavelength shift, which is also large enough to compensate the random wavelength variation due to the random fabrication errors.

Fabrication and Modification of Nanoporous Silicon Particles

NASA Technical Reports Server (NTRS)

Ferrari, Mauro; Liu, Xuewu

2010-01-01

Silicon-based nanoporous particles as biodegradable drug carriers are advantageous in permeation, controlled release, and targeting. The use of biodegradable nanoporous silicon and silicon dioxide, with proper surface treatments, allows sustained drug release within the target site over a period of days, or even weeks, due to selective surface coating. A variety of surface treatment protocols are available for silicon-based particles to be stabilized, functionalized, or modified as required. Coated polyethylene glycol (PEG) chains showed the effective depression of both plasma protein adsorption and cell attachment to the modified surfaces, as well as the advantage of long circulating. Porous silicon particles are micromachined by lithography. Compared to the synthesis route of the nanomaterials, the advantages include: (1) the capability to make different shapes, not only spherical particles but also square, rectangular, or ellipse cross sections, etc.; (2) the capability for very precise dimension control; (3) the capacity for porosity and pore profile control; and (4) allowance of complex surface modification. The particle patterns as small as 60 nm can be fabricated using the state-of-the-art photolithography. The pores in silicon can be fabricated by exposing the silicon in an HF/ethanol solution and then subjecting the pores to an electrical current. The size and shape of the pores inside silicon can be adjusted by the doping of the silicon, electrical current application, the composition of the electrolyte solution, and etching time. The surface of the silicon particles can be modified by many means to provide targeted delivery and on-site permanence for extended release. Multiple active agents can be co-loaded into the particles. Because the surface modification of particles can be done on wafers before the mechanical release, asymmetrical surface modification is feasible. Starting from silicon wafers, a treatment, such as KOH dipping or reactive ion

Nanophotonic applications for silicon-on-insulator (SOI)

NASA Astrophysics Data System (ADS)

de la Houssaye, Paul R.; Russell, Stephen D.; Shimabukuro, Randy L.

2004-07-01

Silicon-on-insulator is a proven technology for very large scale integration of microelectronic devices. The technology also offers the potential for development of nanophotonic devices and the ability to interface such devices to the macroscopic world. This paper will report on fabrication techniques used to form nano-structured silicon wires on an insulating structure that is amenable to interfacing nanostructured sensors with high-performance microelectronic circuitry for practical implementation. Nanostructures formed on silicon-on-sapphire can also exploit the transparent substrate for novel device geometries. This research harnesses the unique properties of a high-quality single crystal film of silicon on sapphire and uses the film thickness as one of the confinement dimensions. Lateral arrays of silicon nanowires were fabricated in the thin (5 to 20 nm) silicon layer and studied. This technique offers simplified contact to individual wires and provides wire surfaces that are more readily accessible for controlled alteration and device designs.

Reduced adherence of Candida to silane-treated silicone rubber.

PubMed

Price, C L; Williams, D W; Waters, M G J; Coulthwaite, L; Verran, J; Taylor, R L; Stickler, D; Lewis, M A O

2005-07-01

Silicone rubber is widely used in the construction of medical devices that can provide an essential role in the treatment of human illness. However, subsequent microbial colonization of silicone rubber can result in clinical infection or device failure. The objective of this study was to determine the effectiveness of a novel silane-treated silicone rubber in inhibiting microbial adherence and material penetration. Test material was prepared by a combination of argon plasma discharge treatment and fluorinated silane coupling. Chemicophysical changes were then confirmed by X-ray photoelectron spectroscopy, contact-angle measurement, and atomic force microscopy. Two separate adherence assays and a material penetration assay assessed the performance of the new material against four strains of Candida species. Results showed a significant reduction (p < 0.01) of Candida albicans GDH 2346 adherence to silane-treated silicone compared with untreated controls. This reduction was still evident after the incorporation of saliva into the assay. Adherence inhibition also occurred with Candida tropicalis MMU and Candida krusei NCYC, although this was assay dependent. Reduced penetration of silane-treated silicone by Candida was evident when compared to untreated controls, plaster-processed silicone, and acrylic-processed silicone. To summarize, a novel silicone rubber material is described that inhibits both candidal adherence and material penetration. The clinical benefit and performance of this material remains to be determined. Copyright 2005 Wiley Periodicals, Inc.

Rectified Brownian movement in molecular and cell biology

NASA Astrophysics Data System (ADS)

Fox, Ronald F.

1998-02-01

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.

Adaptive control system for line-commutated inverters

NASA Technical Reports Server (NTRS)

Dolland, C. R.; Bailey, D. A. (Inventor)

1983-01-01

A control system for a permanent magnet motor driven by a multiphase line commutated inverter is provided with integration for integrating the back EMF of each phase of the motor. This is used in generating system control signals for an inverter gate logic using a sync and firing angle (alpha) control generator connected to the outputs of the integrators. A precision full wave rectifier provides a speed control feedback signal to a phase delay rectifier via a gain and loop compensation circuit and to the integrators for adaptive control of the attenuation of low frequencies by the integrators as a function of motor speed. As the motor speed increases, the attenuation of low frequency components by the integrators is increased to offset the gain of the integrators to spurious low frequencies.

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

PubMed

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

2014-05-19

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

N-(2-methoxyphenyl) benzenesulfonamide, a novel regulator of neuronal G protein-gated inward rectifier K+ channels.

PubMed

Walsh, Kenneth B; Gay, Elaine A; Blough, Bruce E; Geurkink, David W

2017-11-15

G protein-gated inward rectifier K + (GIRK) channels are members of the super-family of proteins known as inward rectifier K + (Kir) channels and are expressed throughout the peripheral and central nervous systems. Neuronal GIRK channels are the downstream targets of a number of neuromodulators including opioids, somatostatin, dopamine and cannabinoids. Previous studies have demonstrated that the ATP-sensitive K + channel, another member of the Kir channel family, is regulated by sulfonamide drugs. Therefore, to determine if sulfonamides also modulate GIRK channels, we screened a library of arylsulfonamide compounds using a GIRK channel fluorescent assay that utilized pituitary AtT20 cells expressing GIRK channels along with the somatostatin type-2 and -5 receptors. Enhancement of the GIRK channel fluorescent signal by one compound, N-(2-methoxyphenyl) benzenesulfonamide (MPBS), was dependent on the activation of the channel by somatostatin. In whole-cell patch clamp experiments, application of MPBS both shifted the somatostatin concentration-response curve (EC 50 = 3.5nM [control] vs.1.0nM [MPBS]) for GIRK channel activation and increased the maximum GIRK current measured with 100nM somatostatin. However, GIRK channel activation was not observed when MPBS was applied to the cells in the absence of somatostatin. While the MPBS structural analog 4-fluoro-N-(2-methoxyphenyl) benzenesulfonamide also augmented the somatostatin-induced GIRK fluorescent signal, no increase in the signal was observed with the sulfonamides tolbutamide, sulfapyridine and celecoxib. In conclusion, MPBS represents a novel prototypic GPCR-dependent regulator of neuronal GIRK channels. Copyright © 2017 Elsevier B.V. All rights reserved.

Rapid fabrication of a silicon modification layer on silicon carbide substrate.

PubMed

Bai, Yang; Li, Longxiang; Xue, Donglin; Zhang, Xuejun

2016-08-01

We develop a kind of magnetorheological (MR) polishing fluid for the fabrication of a silicon modification layer on a silicon carbide substrate based on chemical theory and actual polishing requirements. The effect of abrasive concentration in MR polishing fluid on material removal rate and removal function shape is investigated. We conclude that material removal rate will increase and tends to peak value as the abrasive concentration increases to 0.3 vol. %, and the removal function profile will become steep, which is a disadvantage to surface frequency error removal at the same time. The removal function stability is also studied and the results show that the prepared MR polishing fluid can satisfy actual fabrication requirements. An aspheric reflective mirror of silicon carbide modified by silicon is well polished by combining magnetorheological finishing (MRF) using two types of MR polishing fluid and computer controlled optical surfacing (CCOS) processes. The surface accuracy root mean square (RMS) is improved from 0.087λ(λ=632.8  nm) initially to 0.020λ(λ=632.8  nm) in 5.5 h total and the tool marks resulting from MRF are negligible. The PSD analysis results also shows that the final surface is uniformly polished.

Electrical Control of g-Factor in a Few-Hole Silicon Nanowire MOSFET.

PubMed

Voisin, B; Maurand, R; Barraud, S; Vinet, M; Jehl, X; Sanquer, M; Renard, J; De Franceschi, S

2016-01-13

Hole spins in silicon represent a promising yet barely explored direction for solid-state quantum computation, possibly combining long spin coherence, resulting from a reduced hyperfine interaction, and fast electrically driven qubit manipulation. Here we show that a silicon-nanowire field-effect transistor based on state-of-the-art silicon-on-insulator technology can be operated as a few-hole quantum dot. A detailed magnetotransport study of the first accessible hole reveals a g-factor with unexpectedly strong anisotropy and gate dependence. We infer that these two characteristics could enable an electrically driven g-tensor-modulation spin resonance with Rabi frequencies exceeding several hundred mega-Hertz.

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds

NASA Astrophysics Data System (ADS)

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

2009-01-01

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 Na 8Si 46. Type II clathrate compound Na xSi 136 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.

Low cost solar array project. Experimental process system development unit for producing semiconductor-grade silicon using the silane-to-silicon process

NASA Technical Reports Server (NTRS)

1980-01-01

Technical activities are reported in the design of process, facilities, and equipment for producing silicon at a rate and price comensurate with production goals for low cost solar cell modules. The silane-silicone process has potential for providing high purity poly-silicon on a commercial scale at a price of fourteen dollars per kilogram by 1986, (1980 dollars). Commercial process, economic analysis, process support research and development, and quality control are discussed.

High Detectivity Graphene-Silicon Heterojunction Photodetector.

PubMed

Li, Xinming; Zhu, Miao; Du, Mingde; Lv, Zheng; Zhang, Li; Li, Yuanchang; Yang, Yao; Yang, Tingting; Li, Xiao; Wang, Kunlin; Zhu, Hongwei; Fang, Ying

2016-02-03

A graphene/n-type silicon (n-Si) heterojunction has been demonstrated to exhibit strong rectifying behavior and high photoresponsivity, which can be utilized for the development of high-performance photodetectors. However, graphene/n-Si heterojunction photodetectors reported previously suffer from relatively low specific detectivity due to large dark current. Here, by introducing a thin interfacial oxide layer, the dark current of graphene/n-Si heterojunction has been reduced by two orders of magnitude at zero bias. At room temperature, the graphene/n-Si photodetector with interfacial oxide exhibits a specific detectivity up to 5.77 × 10(13) cm Hz(1/2) W(-1) at the peak wavelength of 890 nm in vacuum, which is highest reported detectivity at room temperature for planar graphene/Si heterojunction photodetectors. In addition, the improved graphene/n-Si heterojunction photodetectors possess high responsivity of 0.73 A W(-1) and high photo-to-dark current ratio of ≈10(7) . The current noise spectral density of the graphene/n-Si photodetector has been characterized under ambient and vacuum conditions, which shows that the dark current can be further suppressed in vacuum. These results demonstrate that graphene/Si heterojunction with interfacial oxide is promising for the development of high detectivity photodetectors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structural determinants of PIP(2) regulation of inward rectifier K(ATP) channels.

PubMed

Shyng, S L; Cukras, C A; Harwood, J; Nichols, C G

2000-11-01

Phosphatidylinositol 4,5-bisphosphate (PIP(2)) activates K(ATP) and other inward rectifier (Kir) channels. To determine residues important for PIP(2) regulation, we have systematically mutated each positive charge in the COOH terminus of Kir6.2 to alanine. The effects of these mutations on channel function were examined using (86)Rb efflux assays on intact cells and inside-out patch-clamp methods. Both methods identify essentially the same basic residues in two narrow regions (176-222 and 301-314) in the COOH terminus that are important for the maintenance of channel function and interaction with PIP(2). Only one residue (R201A) simultaneously affected ATP and PIP(2) sensitivity, which is consistent with the notion that these ligands, while functionally competitive, are unlikely to bind to identical sites. Strikingly, none of 13 basic residues in the terminal portion (residues 315-390) of the COOH terminus affected channel function when neutralized. The data help to define the structural requirements for PIP(2) sensitivity of K(ATP) channels. Moreover, the regions and residues defined in this study parallel those uncovered in recent studies of PIP(2) sensitivity in other inward rectifier channels, indicating a common structural basis for PIP(2) regulation.

Silicon Web Process Development. [for solar cell fabrication

NASA Technical Reports Server (NTRS)

Duncan, C. S.; Seidensticker, R. G.; Hopkins, R. H.; Mchugh, J. P.; Hill, F. E.; Heimlich, M. E.; Driggers, J. M.

1979-01-01

Silicon dendritic web, ribbon form of silicon and capable of fabrication into solar cells with greater than 15% AMl conversion efficiency, was produced from the melt without die shaping. Improvements were made both in the width of the web ribbons grown and in the techniques to replenish the liquid silicon as it is transformed to web. Through means of improved thermal shielding stress was reduced sufficiently so that web crystals nearly 4.5 cm wide were grown. The development of two subsystems, a silicon feeder and a melt level sensor, necessary to achieve an operational melt replenishment system, is described. A gas flow management technique is discussed and a laser reflection method to sense and control the melt level as silicon is replenished is examined.

Composition Comprising Silicon Carbide

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Doping of silicon with carbon during laser ablation process

NASA Astrophysics Data System (ADS)

Račiukaitis, G.; Brikas, M.; Kazlauskienė, V.; Miškinis, J.

2006-12-01

The effect of laser ablation on properties of remaining material in silicon was investigated. It was found that laser cutting of wafers in the air induced the doping of silicon with carbon. The effect was more distinct when using higher laser power or UV radiation. Carbon ions created bonds with silicon atoms in the depth of the material. Formation of the silicon carbide type bonds was confirmed by SIMS, XPS and AES measurements. Modeling of the carbon diffusion to clarify its depth profile in silicon was performed. Photochemical reactions of such type changed the structure of material and could be the reason of the reduced machining quality. The controlled atmosphere was applied to prevent carbonization of silicon during laser cutting.

Retinal Layers Measurements following Silicone Oil Tamponade for Retinal Detachment Surgery.

PubMed

Jurišić, Darija; Geber, Mia Zorić; Ćavar, Ivan; Utrobičić, Dobrila Karlica

2017-12-19

This study aimed to investigate the influence of silicone oil on the retinal nerve fiber layer (RNFL) thickness in patients with primary rhegmatogenous retinal detachment who underwent vitreoretinal surgery. The study included 47 patients (eyes), who underwent a pars plana vitrectomy with the silicone oil tamponade. The control group included unoperated eye of all participants. Spectral-domain optical coherence tomography (SD-OCT) was used for the measurements of peripapilar and macular RNFL thickness. The average peripapillary RNFL thickness was significantly higher in the silicone oil filled eyes during endotamponade and after its removal. The eyes with elevated IOP had less thickening of the RNFL in comparison to the eyes with normal IOP. Central macular thickness and macular volume were decreased in the silicone oil filled eyes in comparison to the control eyes. In conclusion, silicone oil caused peripapilar RNFL thickening in the vitrectomized eyes during endotamponade and after silicone oil removal.

Effects of silicone gel on burn scars.

PubMed

Momeni, Mahnoush; Hafezi, Farhad; Rahbar, Hossein; Karimi, Hamid

2009-02-01

To study the efficacy of silicone gel applied to hypertrophic burn scars, in reducing scar interference with normal function and improving cosmesis. A randomised, double-blind, placebo-controlled trial involving 38 people with hypertrophic burn scars. Each scar was divided into two segments; silicone gel sheet was applied randomly to one of the two and placebo to the other. Participants were seen again after 1 and 4 months. Their data and wound characteristics were collected using the Vancouver scar scale. The median age of participants was 22 years (1.5-60 years) and 16 were male; 4 did not attend follow-up and were excluded from the study. There were no significant differences in baseline characteristics. Although after 1 month all scar scale measures were lower in treated areas, only the vascularity scale was significantly different between the two areas. After 4 months, all scale measures were significantly lower in the silicone gel group than in the control group, except for the pain score. Silicone gel is an effective treatment for hypertrophic burn scars.

Controlling charge current through a DNA based molecular transistor

NASA Astrophysics Data System (ADS)

Behnia, S.; Fathizadeh, S.; Ziaei, J.

2017-01-01

Molecular electronics is complementary to silicon-based electronics and may induce electronic functions which are difficult to obtain with conventional technology. We have considered a DNA based molecular transistor and study its transport properties. The appropriate DNA sequence as a central chain in molecular transistor and the functional interval for applied voltages is obtained. I-V characteristic diagram shows the rectifier behavior as well as the negative differential resistance phenomenon of DNA transistor. We have observed the nearly periodic behavior in the current flowing through DNA. It is reported that there is a critical gate voltage for each applied bias which above it, the electrical current is always positive.

Quantum Properties of Dichroic Silicon Vacancies in Silicon Carbide

NASA Astrophysics Data System (ADS)

Nagy, Roland; Widmann, Matthias; Niethammer, Matthias; Dasari, Durga B. R.; Gerhardt, Ilja; Soykal, Öney O.; Radulaski, Marina; Ohshima, Takeshi; Vučković, Jelena; Son, Nguyen Tien; Ivanov, Ivan G.; Economou, Sophia E.; Bonato, Cristian; Lee, Sang-Yun; Wrachtrup, Jörg

2018-03-01

Although various defect centers have displayed promise as either quantum sensors, single photon emitters, or light-matter interfaces, the search for an ideal defect with multifunctional ability remains open. In this spirit, we study the dichroic silicon vacancies in silicon carbide that feature two well-distinguishable zero-phonon lines and analyze the quantum properties in their optical emission and spin control. We demonstrate that this center combines 40% optical emission into the zero-phonon lines showing the contrasting difference in optical properties with varying temperature and polarization, and a 100% increase in the fluorescence intensity upon the spin resonance, and long spin coherence time of their spin-3 /2 ground states up to 0.6 ms. These results single out this defect center as a promising system for spin-based quantum technologies.

Bond Testing for Effects of Silicone Contamination

NASA Technical Reports Server (NTRS)

Plaia, James; Evans, Kurt

2005-01-01

In 2003 ATK Thiokol discovered that the smocks and coveralls worn by its operations personnel for safety and contamination control were themselves contaminated with a silicone defoamer and a silicone oil. As a growing list of items have been identified as having this form of contamination, it was desirable to devise a test method to determine if the contamination level detected could cause subsequent processing concerns. The smocks and coveralls could potentially contact bonding surfaces during processing so the test method focused on dry transfer of the silicone from the clothing to the bonding surface.

Tetrameric subunit structure of the native brain inwardly rectifying potassium channel Kir 2.2.

PubMed

Raab-Graham, K F; Vandenberg, C A

1998-07-31

Strongly inwardly rectifying potassium channels of the Kir 2 subfamily (IRK1, IRK2, and IRK3) are involved in maintenance and modulation of cell excitability in brain and heart. Electrophysiological studies of channels expressed in heterologous systems have suggested that the pore-conducting pathway contains four subunits. However, inferences from electrophysiological studies have not been tested on native channels and do not address the possibility of nonconducting auxiliary subunits. Here, we investigate the subunit stoichiometry of endogenous inwardly rectifying potassium channel Kir 2.2 (IRK2) from rat brain. Using chemical cross-linking, immunoprecipitiation, and velocity sedimentation, we report physical evidence demonstrating the tetrameric organization of the native channel. Kir 2.2 was sequentially cross-linked to produce bands on SDS-polyacrylamide gel electrophoresis corresponding in size to monomer, dimer, trimer, and three forms of tetramer. Fully cross-linked channel was present as a single band of tetrameric size. Immunoprecipitation of biotinylated membranes revealed a single band corresponding to Kir 2.2, suggesting that the channel is composed of a single type of subunit. Hydrodynamic properties of 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulfonic acid-solubilized channel were used to calculate the molecular mass of the channel. Velocity sedimentation in H2O or D2O gave a sharp peak with a sedimentation coefficient of 17.3 S. Gel filtration yielded a Stokes radius of 5.92 nm. These data indicate a multisubunit protein with a molecular mass of 193 kDa, calculated to contain 3.98 subunits. Together, these results demonstrate that Kir 2.2 channels are formed by the homotetrameric association of Kir 2.2 subunits and do not contain tightly associated auxiliary subunits. These studies suggest that Kir 2.2 channels differ in structure from related heterooctomeric ATP-sensitive K channels and heterotetrameric G-protein-regulated inward rectifier K

Lewis-Base-Mediated Diastereoselective Silylations of Alcohols: Synthesis of Silicon-Stereogenic Dialkoxysilanes Controlled by Chiral Aryl BINMOLs.

PubMed

Bai, Xing-Feng; Zou, Jin-Feng; Chen, Mu-Yi; Xu, Zheng; Li, Li; Cui, Yu-Ming; Zheng, Zhan-Jiang; Xu, Li-Wen

2017-07-18

In the past years, stereoselective functionalizations of hydroxyl groups of alcohol substrates with chlorosilanes leading to silyl ether formation have evolved from a functional-group protection to an enantioselective synthetic strategy. This work comprises a controlled desymmetrization of dichlorosilanes by using a family of structurally specific chiral diols, chiral 1,1'-binaphthalene-2-α-arylmethanol-2'-ol (Ar-BINMOL). This process led to the facile construction of silicon-stereogenic organosilicon compounds with high yields and good diastereoselectivities. In addition, the diasteroselective silylation of chiral diols might not only be of interest for the development of highly stereoselective nucleophilic silylation, but also shed light on the construction of novel chiral phosphine ligands bearing a silicon-stereogenic center. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Neuromorphic photonic networks using silicon photonic weight banks.

PubMed

Tait, Alexander N; de Lima, Thomas Ferreira; Zhou, Ellen; Wu, Allie X; Nahmias, Mitchell A; Shastri, Bhavin J; Prucnal, Paul R

2017-08-07

Photonic systems for high-performance information processing have attracted renewed interest. Neuromorphic silicon photonics has the potential to integrate processing functions that vastly exceed the capabilities of electronics. We report first observations of a recurrent silicon photonic neural network, in which connections are configured by microring weight banks. A mathematical isomorphism between the silicon photonic circuit and a continuous neural network model is demonstrated through dynamical bifurcation analysis. Exploiting this isomorphism, a simulated 24-node silicon photonic neural network is programmed using "neural compiler" to solve a differential system emulation task. A 294-fold acceleration against a conventional benchmark is predicted. We also propose and derive power consumption analysis for modulator-class neurons that, as opposed to laser-class neurons, are compatible with silicon photonic platforms. At increased scale, Neuromorphic silicon photonics could access new regimes of ultrafast information processing for radio, control, and scientific computing.

Density control of dodecamanganese clusters anchored on silicon(100).

PubMed

Condorelli, Guglielmo G; Motta, Alessandro; Favazza, Maria; Nativo, Paola; Fragalà, Ignazio L; Gatteschi, Dante

2006-04-24

A synthetic strategy to control the density of Mn12 clusters anchored on silicon(100) was investigated. Diluted monolayers suitable for Mn12 anchoring were prepared by Si-grafting mixtures of the methyl 10-undecylenoate precursor ligand with 1-decene spectator spacers. Different ratios of these mixtures were tested. The grafted surfaces were hydrolyzed to reveal the carboxylic groups available for the subsequent exchange with the [Mn12O12(OAc)16(H2O)4]4 H2O2 AcOH cluster. Modified surfaces were analyzed by attenuated total reflection (ATR)-FTIR spectroscopy, X-ray photoemission spectroscopy (XPS), and AFM imaging. Results of XPS and ATR-FTIR spectroscopy show that the surface mole ratio between grafted ester and decene is higher than in the source solution. The surface density of the Mn12 cluster is, in turn, strictly proportional to the ester mole fraction. Well-resolved and isolated clusters were observed by AFM, using a diluted ester/decene 1:1 solution.

Thermoelectric properties of nanostructured porous silicon

NASA Astrophysics Data System (ADS)

Martín-Palma, R. J.; Cabrera, H.; Martín-Adrados, B.; Korte, D.; Pérez-Cappe, E.; Mosqueda, Y.; Frutis, M. A.; Danguillecourt, E.

2018-01-01

In this work we report on the thermoelectric properties of nanostructured porous silicon (nanoPS) layers grown onto silicon substrates. More specifically, nanoPS layers of different porosity, nanocrystal size, and thickness were fabricated and their electrical conductivities, Seebeck coefficients, and thermal conductivities were subsequently measured. It was found that these parameters show a strong dependence on the characteristics of the nanoPS layers and thus can be controlled.

Drug delivery via porous silicon: a focused patent review.

PubMed

Kulyavtsev, Paulina A; Spencer, Roxanne P

2017-03-01

Although silicon is more commonly associated with computer chips than with drug delivery, with the discovery that porous silicon is a viable biocompatible material, mesoporous silicon with pores between 2 and 50 nm has been loaded with small molecule and biomolecule therapeutics and safely implanted for controlled release. As porous silicon is readily oxidized, porous silica must also be considered for drug delivery applications. Since 2010, only a limited number of US patents have been granted, primarily for ophthalmologic and immunotherapy applications, in contrast to the growing body of technical literature in this area.

Failure rates for accelerated acceptance testing of silicon transistors

NASA Technical Reports Server (NTRS)

Toye, C. R.

1968-01-01

Extrapolation tables for the control of silicon transistor product reliability have been compiled. The tables are based on a version of the Arrhenius statistical relation and are intended to be used for low- and medium-power silicon transistors.

Photonic Crystal Sensors Based on Porous Silicon

PubMed Central

Pacholski, Claudia

2013-01-01

Porous silicon has been established as an excellent sensing platform for the optical detection of hazardous chemicals and biomolecular interactions such as DNA hybridization, antigen/antibody binding, and enzymatic reactions. Its porous nature provides a high surface area within a small volume, which can be easily controlled by changing the pore sizes. As the porosity and consequently the refractive index of an etched porous silicon layer depends on the electrochemial etching conditions photonic crystals composed of multilayered porous silicon films with well-resolved and narrow optical reflectivity features can easily be obtained. The prominent optical response of the photonic crystal decreases the detection limit and therefore increases the sensitivity of porous silicon sensors in comparison to sensors utilizing Fabry-Pérot based optical transduction. Development of porous silicon photonic crystal sensors which allow for the detection of analytes by the naked eye using a simple color change or the fabrication of stacked porous silicon photonic crystals showing two distinct optical features which can be utilized for the discrimination of analytes emphasize its high application potential. PMID:23571671

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

NASA Astrophysics Data System (ADS)

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

2017-07-01

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

Thin Carbon Layers on Nanostructured Silicon-Properties and Applications

NASA Astrophysics Data System (ADS)

Angelescu, Anca; Kleps, Irina; Miu, Mihaela; Simion, Monica; Bragaru, Adina; Petrescu, Stefana; Paduraru, Crina; Raducanu, Aurelia

Thin carbon layers such as silicon carbide (SiC) and diamond like carbon (DLC) layers on silicon, or on nanostructured silicon substrats were obtained by different methods. This paper is a review of our results in the areas of carbon layer microfabrication technologies and their properties related to different microsystem apllications. So, silicon membranes using a-SiC or DLC layers as etching mask, as well as silicon carbide membranes using a combined porous silicon — DLC structure were fabricated for sensor applications. A detailed evaluation of the field emission (FE) properties of these films was done to demonstrate their capability to be used in field emission devices. Carbon thin layers on nanostructured silicon samples were also investigated with respect to the living cell adhesion on these structures. The experiments indicate that the cell attachment on the surface of carbon coatings can be controlled by deposition parameters during the technological process.

Improved Ablation Resistance of Silicone Rubber Composites by Introducing Montmorillonite and Silicon Carbide Whisker

PubMed Central

Zhang, Guangwu; Wang, Fuzhong; Huang, Zhixiong; Dai, Jing; Shi, Minxian

2016-01-01

Montmorillonite (MMT) was added to silicone rubber (SR) to improve the ablation resistance of the silicone. Following this, different quantities of silicon carbide whiskers (SiCw) were incorporated into the MMT/SR to yield a hybrid, ablative composite. The tensile strength and elongation at break of the composite increased after the addition of MMT. The ablation test results showed that MMT helped to form a covering layer by bonding with the silica and other components on the ablated surface. The linear and mass ablation rates exhibited decreases of 22.5% and 18.2%, respectively, in comparison to a control sample. After further incorporation of SiCw as the second filler, the resulting composites exhibited significantly higher tensile strength and ablation resistance, but not particularly lower elongation at break in comparison to the control sample. The SiCw/MMT fillers were beneficial in forming a dense and compact covering layer that delayed the heat and oxygen diffusion into the inner layers, which improved the ablation properties effectively. The remaining whiskers acted as a micro skeleton to maintain the composite’s char strength. Compared to the control sample, the linear and mass ablation rates of the composite after incorporating 6 phr SiCw and 10 phr MMT decreased by 59.2% and 43.6%, respectively. These experimental results showed that the fabricated composites exhibited outstanding mechanical properties and excellent ablation resistance. PMID:28773846

Improved Ablation Resistance of Silicone Rubber Composites by Introducing Montmorillonite and Silicon Carbide Whisker.

PubMed

Zhang, Guangwu; Wang, Fuzhong; Huang, Zhixiong; Dai, Jing; Shi, Minxian

2016-08-24

Montmorillonite (MMT) was added to silicone rubber (SR) to improve the ablation resistance of the silicone. Following this, different quantities of silicon carbide whiskers (SiCw) were incorporated into the MMT/SR to yield a hybrid, ablative composite. The tensile strength and elongation at break of the composite increased after the addition of MMT. The ablation test results showed that MMT helped to form a covering layer by bonding with the silica and other components on the ablated surface. The linear and mass ablation rates exhibited decreases of 22.5% and 18.2%, respectively, in comparison to a control sample. After further incorporation of SiCw as the second filler, the resulting composites exhibited significantly higher tensile strength and ablation resistance, but not particularly lower elongation at break in comparison to the control sample. The SiCw/MMT fillers were beneficial in forming a dense and compact covering layer that delayed the heat and oxygen diffusion into the inner layers, which improved the ablation properties effectively. The remaining whiskers acted as a micro skeleton to maintain the composite's char strength. Compared to the control sample, the linear and mass ablation rates of the composite after incorporating 6 phr SiCw and 10 phr MMT decreased by 59.2% and 43.6%, respectively. These experimental results showed that the fabricated composites exhibited outstanding mechanical properties and excellent ablation resistance.

Weakly modulated silicon-dioxide-cladding gratings for silicon waveguide Fabry-Pérot cavities.

PubMed

Grote, Richard R; Driscoll, Jeffrey B; Biris, Claudiu G; Panoiu, Nicolae C; Osgood, Richard M

2011-12-19

We show by theory and experiment that silicon-dioxide-cladding gratings for Fabry-Pérot cavities on silicon-on-insulator channel ("wire") waveguides provide a low-refractive-index perturbation, which is required for several important integrated photonics components. The underlying refractive index perturbation of these gratings is significantly weaker than that of analogous silicon gratings, leading to finer control of the coupling coefficient κ. Our Fabry-Pérot cavities are designed using the transfer-matrix method (TMM) in conjunction with the finite element method (FEM) for calculating the effective index of each waveguide section. Device parameters such as coupling coefficient, κ, Bragg mirror stop band, Bragg mirror reflectivity, and quality factor Q are examined via TMM modeling. Devices are fabricated with representative values of distributed Bragg reflector lengths, cavity lengths, and propagation losses. The measured transmission spectra show excellent agreement with the FEM/TMM calculations.

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

PubMed

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

2013-02-21

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

Quantitative analysis of the Ca2+ -dependent regulation of delayed rectifier K+ current IKs in rabbit ventricular myocytes.

PubMed

Bartos, Daniel C; Morotti, Stefano; Ginsburg, Kenneth S; Grandi, Eleonora; Bers, Donald M

2017-04-01

[Ca 2+ ] i enhanced rabbit ventricular slowly activating delayed rectifier K + current (I Ks ) by negatively shifting the voltage dependence of activation and slowing deactivation, similar to perfusion of isoproterenol. Rabbit ventricular rapidly activating delayed rectifier K + current (I Kr ) amplitude and voltage dependence were unaffected by high [Ca 2+ ] i . When measuring or simulating I Ks during an action potential, I Ks was not different during a physiological Ca 2+ transient or when [Ca 2+ ] i was buffered to 500 nm. The slowly activating delayed rectifier K + current (I Ks ) contributes to repolarization of the cardiac action potential (AP). Intracellular Ca 2+ ([Ca 2+ ] i ) and β-adrenergic receptor (β-AR) stimulation modulate I Ks amplitude and kinetics, but details of these important I Ks regulators and their interaction are limited. We assessed the [Ca 2+ ] i dependence of I Ks in steady-state conditions and with dynamically changing membrane potential and [Ca 2+ ] i during an AP. I Ks was recorded from freshly isolated rabbit ventricular myocytes using whole-cell patch clamp. With intracellular pipette solutions that controlled free [Ca 2+ ] i , we found that raising [Ca 2+ ] i from 100 to 600 nm produced similar increases in I Ks as did β-AR activation, and the effects appeared additive. Both β-AR activation and high [Ca 2+ ] i increased maximally activated tail I Ks , negatively shifted the voltage dependence of activation, and slowed deactivation kinetics. These data informed changes in our well-established mathematical model of the rabbit myocyte. In both AP-clamp experiments and simulations, I Ks recorded during a normal physiological Ca 2+ transient was similar to I Ks measured with [Ca 2+ ] i clamped at 500-600 nm. Thus, our study provides novel quantitative data as to how physiological [Ca 2+ ] i regulates I Ks amplitude and kinetics during the normal rabbit AP. Our results suggest that micromolar [Ca 2+ ] i , in the submembrane or

Amorphous Silicon Nanowires Grown on Silicon Oxide Film by Annealing

NASA Astrophysics Data System (ADS)

Yuan, Zhishan; Wang, Chengyong; Chen, Ke; Ni, Zhonghua; Chen, Yunfei

2017-08-01

In this paper, amorphous silicon nanowires (α-SiNWs) were synthesized on (100) Si substrate with silicon oxide film by Cu catalyst-driven solid-liquid-solid mechanism (SLS) during annealing process (1080 °C for 30 min under Ar/H2 atmosphere). Micro size Cu pattern fabrication decided whether α-SiNWs can grow or not. Meanwhile, those micro size Cu patterns also controlled the position and density of wires. During the annealing process, Cu pattern reacted with SiO2 to form Cu silicide. More important, a diffusion channel was opened for Si atoms to synthesis α-SiNWs. What is more, the size of α-SiNWs was simply controlled by the annealing time. The length of wire was increased with annealing time. However, the diameter showed the opposite tendency. The room temperature resistivity of the nanowire was about 2.1 × 103 Ω·cm (84 nm diameter and 21 μm length). This simple fabrication method makes application of α-SiNWs become possible.

Amorphous Silicon Nanowires Grown on Silicon Oxide Film by Annealing.

PubMed

Yuan, Zhishan; Wang, Chengyong; Chen, Ke; Ni, Zhonghua; Chen, Yunfei

2017-08-10

In this paper, amorphous silicon nanowires (α-SiNWs) were synthesized on (100) Si substrate with silicon oxide film by Cu catalyst-driven solid-liquid-solid mechanism (SLS) during annealing process (1080 °C for 30 min under Ar/H 2 atmosphere). Micro size Cu pattern fabrication decided whether α-SiNWs can grow or not. Meanwhile, those micro size Cu patterns also controlled the position and density of wires. During the annealing process, Cu pattern reacted with SiO 2 to form Cu silicide. More important, a diffusion channel was opened for Si atoms to synthesis α-SiNWs. What is more, the size of α-SiNWs was simply controlled by the annealing time. The length of wire was increased with annealing time. However, the diameter showed the opposite tendency. The room temperature resistivity of the nanowire was about 2.1 × 10 3  Ω·cm (84 nm diameter and 21 μm length). This simple fabrication method makes application of α-SiNWs become possible.

A surface code quantum computer in silicon

PubMed Central

Hill, Charles D.; Peretz, Eldad; Hile, Samuel J.; House, Matthew G.; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y.; Hollenberg, Lloyd C. L.

2015-01-01

The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel—posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited. PMID:26601310

A surface code quantum computer in silicon.

PubMed

Hill, Charles D; Peretz, Eldad; Hile, Samuel J; House, Matthew G; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y; Hollenberg, Lloyd C L

2015-10-01

The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel-posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited.

Method for forming silicon on a glass substrate

DOEpatents

McCarthy, Anthony M.

1995-01-01

A method by which single-crystal silicon microelectronics may be fabricated on glass substrates at unconventionally low temperatures. This is achieved by fabricating a thin film of silicon on glass and subsequently forming the doped components by a short wavelength (excimer) laser doping procedure and conventional patterning techniques. This method may include introducing a heavily boron doped etch stop layer on a silicon wafer using an excimer laser, which permits good control of the etch stop layer removal process. This method additionally includes dramatically reducing the remaining surface roughness of the silicon thin films after etching in the fabrication of silicon on insulator wafers by scanning an excimer laser across the surface of the silicon thin film causing surface melting, whereby the surface tension of the melt causes smoothing of the surface during recrystallization. Applications for this method include those requiring a transparent or insulating substrate, such as display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard and high temperature electronics.

Method for forming silicon on a glass substrate

DOEpatents

McCarthy, A.M.

1995-03-07

A method by which single-crystal silicon microelectronics may be fabricated on glass substrates at unconventionally low temperatures. This is achieved by fabricating a thin film of silicon on glass and subsequently forming the doped components by a short wavelength (excimer) laser doping procedure and conventional patterning techniques. This method may include introducing a heavily boron doped etch stop layer on a silicon wafer using an excimer laser, which permits good control of the etch stop layer removal process. This method additionally includes dramatically reducing the remaining surface roughness of the silicon thin films after etching in the fabrication of silicon on insulator wafers by scanning an excimer laser across the surface of the silicon thin film causing surface melting, whereby the surface tension of the melt causes smoothing of the surface during recrystallization. Applications for this method include those requiring a transparent or insulating substrate, such as display manufacturing. Other applications include sensors, actuators, optoelectronics, radiation hard and high temperature electronics. 15 figs.

Method of making silicon carbide-silicon composite having improved oxidation resistance

NASA Technical Reports Server (NTRS)

Wang, Hongyu (Inventor); Luthra, Krishan Lal (Inventor)

2002-01-01

A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

Tailored porous silicon microparticles: fabrication and properties

PubMed Central

Chiappini, Ciro; Tasciotti, Ennio; Fakhoury, Jean R.; Fine, Daniel; Pullan, Lee; Wang, Young-Chung; Fu, Lianfeng

2010-01-01

The use of mesoporous silicon particles for drug delivery has been widely explored thanks to their biodegradability and biocompatibility. The ability to tailor the physicochemical properties of porous silicon at the micro and nano scale confers versatility to this material. We present a method for the fabrication of highly reproducible, monodisperse mesoporous silicon particles with controlled physical characteristics through electrochemical etch of patterned silicon trenches. We tailored particle size in the micrometer range and pore size in the nanometer range, shape from tubular to discoidal to hemispherical, and porosity from 46% to over 80%. In addition, we correlated the properties of the porous matrix with the loading of model nanoparticles (Q-dots) and observed their three-dimensional arrangement within the matrix by transmission electron microscopy tomography. The methods developed in this study provide effective means to fabricate mesoporous silicon particles according to the principles of rational design for therapeutic vectors and to characterize the distribution of nanoparticles within the porous matrix PMID:20162656

Silicon graphene Bragg gratings.

PubMed

Capmany, José; Domenech, David; Muñoz, Pascual

2014-03-10

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

Solar silicon from directional solidification of MG silicon produced via the silicon carbide route

NASA Technical Reports Server (NTRS)

Rustioni, M.; Margadonna, D.; Pirazzi, R.; Pizzini, S.

1986-01-01

A process of metallurgical grade (MG) silicon production is presented which appears particularly suitable for photovoltaic (PV) applications. The MG silicon is prepared in a 240 KVA, three electrode submerged arc furnace, starting from high grade quartz and high purity silicon carbide. The silicon smelted from the arc furnace was shown to be sufficiently pure to be directionally solidified to 10 to 15 kg. After grinding and acid leaching, had a material yield larger than 90%. With a MG silicon feedstock containing 3 ppmw B, 290 ppmw Fe, 190 ppmw Ti, and 170 ppmw Al, blended with 50% of off grade electronic grade (EG) silicon to reconduct the boron content to a concentration acceptable for solar cell fabrication, the 99% of deep level impurities were concentrated in the last 5% of the ingot. Quite remarkably this material has OCV values higher tham 540 mV and no appreciable shorts due to SiC particles.

Colloidal characterization of ultrafine silicon carbide and silicon nitride powders

NASA Technical Reports Server (NTRS)

Whitman, Pamela K.; Feke, Donald L.

1986-01-01

The effects of various powder treatment strategies on the colloid chemistry of aqueous dispersions of silicon carbide and silicon nitride are examined using a surface titration methodology. Pretreatments are used to differentiate between the true surface chemistry of the powders and artifacts resulting from exposure history. Silicon nitride powders require more extensive pretreatment to reveal consistent surface chemistry than do silicon carbide powders. As measured by titration, the degree of proton adsorption from the suspending fluid by pretreated silicon nitride and silicon carbide powders can both be made similar to that of silica.

Electrochemical method for defect delineation in silicon-on-insulator wafers

DOEpatents

Guilinger, Terry R.; Jones, Howland D. T.; Kelly, Michael J.; Medernach, John W.; Stevenson, Joel O.; Tsao, Sylvia S.

1991-01-01

An electrochemical method for defect delineation in thin-film SOI or SOS wafers in which a surface of a silicon wafer is electrically connected so as to control the voltage of the surface within a specified range, the silicon wafer is then contacted with an electrolyte, and, after removing the electrolyte, defects and metal contamination in the silicon wafer are identified.

β1-Adrenoceptor autoantibodies affect action potential duration and delayed rectifier potassium currents in guinea pigs.

PubMed

Zhao, Yuhui; Huang, Haixia; Du, Yunhui; Li, Xiao; Lv, Tingting; Zhang, Suli; Wei, Hua; Shang, Jianyu; Liu, Ping; Liu, Huirong

2015-01-01

β1-Adrenoceptor autoantibodies (β1-AAs) affect the action potential duration (APD) in cardiomyocytes and are related to ventricular arrhythmias. The delayed rectifier potassium current (I K) plays a crucial role in APD, but the effects of β1-AAs on I K have not been completely illuminated. This work aimed to observe the effects of β1-AAs on I K and APD and further explore the mechanisms of β1-AA-mediated ventricular arrhythmias. β1-AAs were obtained from sera of patients with coronary heart disease (CHD) and nonsustained ventricular tachycardia. With whole-cell patch clamp technique, action potentials and I K were recorded. The results illustrated 0.1 μmol/L β1-AAs shortened APD at 50 % (APD50) and 90 % (APD90) of the repolarization. However, at 0.01 μmol/L, β1-AAs had no effects on either APD90 or APD50 (P > 0.05). At 0.001 μmol/L, β1-AAs significantly prolonged APD90 and APD50. Moreover, β1-AAs (0.001, 0.01, 0.1 μmol/L) dose-dependently increased the rapidly activating delayed rectifier potassium current (I Kr), but similarly decreased the slowly activating delayed rectifier potassium current (I Ks) and increased L-type calcium currents at the different concentrations. Taken together, the IKr increase induced by high β1-AA concentrations is responsible for a significant APD reduction which would contribute to repolarization changes and trigger the malignant ventricular arrhythmias in CHD patients.

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

NASA Astrophysics Data System (ADS)

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

2013-03-01

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

The electrophotonic silicon biosensor

NASA Astrophysics Data System (ADS)

Juan-Colás, José; Parkin, Alison; Dunn, Katherine E.; Scullion, Mark G.; Krauss, Thomas F.; Johnson, Steven D.

2016-09-01

The emergence of personalized and stratified medicine requires label-free, low-cost diagnostic technology capable of monitoring multiple disease biomarkers in parallel. Silicon photonic biosensors combine high-sensitivity analysis with scalable, low-cost manufacturing, but they tend to measure only a single biomarker and provide no information about their (bio)chemical activity. Here we introduce an electrochemical silicon photonic sensor capable of highly sensitive and multiparameter profiling of biomarkers. Our electrophotonic technology consists of microring resonators optimally n-doped to support high Q resonances alongside electrochemical processes in situ. The inclusion of electrochemical control enables site-selective immobilization of different biomolecules on individual microrings within a sensor array. The combination of photonic and electrochemical characterization also provides additional quantitative information and unique insight into chemical reactivity that is unavailable with photonic detection alone. By exploiting both the photonic and the electrical properties of silicon, the sensor opens new modalities for sensing on the microscale.

Silicon Biomineralization on the Earth

NASA Astrophysics Data System (ADS)

Mitra, D.; Das, S.

2010-12-01

Silicon biomineralization in nature occurs as either ‘biologically controlled biomineralization’; where silicon is precipitated to serve some physiological purpose; or as ‘biologically induced biomineralization’; where mineralization occurs as a byproduct of cell’s metabolic activity or through its interactions with the environment. In biologically controlled mineralization, there is an overwhelming control of the microorganism on nucleation and mineral growth stage. There is delineation of space (as intracellular silica deposition vesicle (SDV)) for the locus of mineralization, which is sealed off from the external environment. Then silicate is sequestered and transferred to the mineralization site by energy driven (energy may be derived from photosynthesis or from glucose metabolism) pump mechanism in presence of specific transporter protein. In biologically induced biomineralization, first, there is silicon nucleation, which leads to the spontaneous growth of some critical nuclei which are resistant to rapid dissolution. Then growth of these silicon nuclei (if the ions are same) or precipitation over the nuclei (if the ions are different) occurs. Ultimately the initial amorphous phase is converted into a crystalline phase. Silicon deposition may also occur due to Ostwald ripening. If silica concentration is more than the solubility of amorphous silica (at 100oC ~ 380 mg L-1), monomeric silica [Si(OH)4] is formed which is converted into oligomers (dimers, trimers and tetramers) by polymerization. Ultimately large polymers of silanol (-Si-OH-) and siloxane (-Si-O-Si-) are formed. Silicification then occurs by hydrogen bonding with neutrally charged polysaccharides, by cation bridging with the cell wall or by direct electrostatic interactions with cationic amino groups present in protein-rich biofilms. Diatoms are the world’s largest contributor to biomineralization of silicon. Diatom silicon transporters (SITs) are membrane associated proteins that

Develop Silicone Encapsulation Systems for Terrestrial Silicon Solar Arrays

NASA Technical Reports Server (NTRS)

1979-01-01

The results for Task 3 of the Low Cost Solar Array Project are presented. Task 3 is directed toward the development of a cost effective encapsulating system for photovoltaic modules using silicon based materials. The technical approach of the contract effort is divided into four special tasks: (1) technology review; (2) generation of concepts for screening and processing silicon encapsulation systems; (3) assessment of encapsulation concepts; and (4) evaluation of encapsulation concepts. The candidate silicon materials are reviewed. The silicon and modified silicon resins were chosen on the basis of similarity to materials with known weatherability, cost, initial tangential modulus, accelerated dirt pick-up test results and the ratio of the content of organic phenyl substitution of methyl substitution on the backbone of the silicon resin.

Design and analysis of an automatic method of measuring silicon-controlled-rectifier holding current

NASA Technical Reports Server (NTRS)

Maslowski, E. A.

1971-01-01

The design of an automated SCR holding-current measurement system is described. The circuits used in the measurement system were designed to meet the major requirements of automatic data acquisition, reliability, and repeatability. Performance data are presented and compared with calibration data. The data verified the accuracy of the measurement system. Data taken over a 48-hr period showed that the measurement system operated satisfactorily and met all the design requirements.

Colloidal synthesis of silicon nanoparticles in molten salts.

PubMed

Shavel, A; Guerrini, L; Alvarez-Puebla, R A

2017-06-22

Silicon nanoparticles are unique materials with applications in a variety of fields, from electronics to catalysis and biomedical uses. Despite technological advancements in nanofabrication, the development of a simple and inexpensive route for the synthesis of homogeneous silicon nanoparticles remains highly challenging. Herein, we describe a new, simple and inexpensive colloidal synthetic method for the preparation, under normal pressure and mild temperature conditions, of relatively homogeneous spherical silicon nanoparticles of either ca. 4 or 6 nm diameter. The key features of this method are the selection of a eutectic salt mixture as a solvent, the identification of appropriate silicon alkoxide precursors, and the unconventional use of alkali earth metals as shape-controlling agents.

Advancements in silicon web technology

NASA Technical Reports Server (NTRS)

Hopkins, R. H.; Easoz, J.; Mchugh, J. P.; Piotrowski, P.; Hundal, R.

1987-01-01

Low defect density silicon web crystals up to 7 cm wide are produced from systems whose thermal environments are designed for low stress conditions using computer techniques. During growth, the average silicon melt temperature, the lateral melt temperature distribution, and the melt level are each controlled by digital closed loop systems to maintain thermal steady state and to minimize the labor content of the process. Web solar cell efficiencies of 17.2 pct AM1 have been obtained in the laboratory while 15 pct efficiencies are common in pilot production.

Ti-Doped GaOx Resistive Switching Memory with Self-Rectifying Behavior by Using NbOx/Pt Bilayers.

PubMed

Park, Ju Hyun; Jeon, Dong Su; Kim, Tae Geun

2017-12-13

Crossbar arrays (CBAs) with resistive random access memory (ReRAM) constitute an established architecture for high-density memory. However, sneak paths via unselected cells increase the total power consumption of these devices and limit the array size. To eliminate such sneak-path problems, we propose a Ti/GaO x /NbO x /Pt structure with a self-rectifying resistive-switching (RS) behavior. In this structure, to reduce the operating voltage, we used a Ti/GaO x stack to increase the number of trap sites in the RS GaO x layer through interfacial reactions between the Ti and GaO x layers. This increase enables easier carrier transport with reduced electric fields. We then adopted a NbO x /Pt stack to add rectifying behavior to the RS GaO x layer. This behavior is a result of the large Schottky barrier height between the NbO x and Pt layers. Finally, both the Ti/GaO x and NbO x /Pt stacks were combined to realize a self-rectifying ReRAM device, which exhibited excellent performance. Characteristics of the device include a low operating voltage range (-2.8 to 2.5 V), high on/off ratios (∼20), high selectivity (∼10 4 ), high operating speeds (200-500 ns), a very low forming voltage (∼3 V), stable operation, and excellent uniformity for high-density CBA-based ReRAM applications.

Laser-induced amorphization of silicon during pulsed-laser irradiation of TiN/Ti/polycrystalline silicon/SiO2/silicon

NASA Astrophysics Data System (ADS)

Chong, Y. F.; Pey, K. L.; Wee, A. T. S.; Thompson, M. O.; Tung, C. H.; See, A.

2002-11-01

In this letter, we report on the complex solidification structures formed during laser irradiation of a titanium nitride/titanium/polycrystalline silicon/silicon dioxide/silicon film stack. Due to enhanced optical coupling, the titanium nitride/titanium capping layer increases the melt depth of polycrystalline silicon by more than a factor of 2. It is found that the titanium atoms diffuse through the entire polycrystalline silicon layer during irradiation. Contrary to the expected polycrystalline silicon growth, distinct regions of polycrystalline and amorphous silicon are formed instead. Possible mechanisms for the formation of these microstructures are proposed.

Rectifying the Optical-Field-Induced Current in Dielectrics: Petahertz Diode.

PubMed

Lee, J D; Yun, Won Seok; Park, Noejung

2016-02-05

Investigating a theoretical model of the optical-field-induced current in dielectrics driven by strong few-cycle laser pulses, we propose an asymmetric conducting of the current by forming a heterojunction made of two distinct dielectrics with a low hole mass (m_{h}^{*}≪m_{e}^{*}) and low electron mass (m_{e}^{*}≪m_{h}^{*}), respectively. This proposition introduces the novel concept of a petahertz (10^{15}  Hz) diode to rectify the current in the petahertz domain, which should be a key ingredient for the electric signal manipulation of future light-wave electronics. Further, we suggest the candidate dielectrics for the heterojunction.

Foundry Technologies Focused on Environmental and Ecological Applications

NASA Astrophysics Data System (ADS)

Roizin, Ya.; Lisiansky, M.; Pikhay, E.

Solutions allowing fabrication of remote control systems with integrated sensors (motes) were introduced as a part of CMOS foundry production platform and verified on silicon. The integrated features include sensors employing principles previously verified in the development of ultra-low power consuming non-volatile memories (C-Flash, MRAM) and components allowing low-power energy harvesting (low voltage rectifiers, high -voltage solar cells). The developed systems are discussed with emphasis on their environmental and security applications.

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

DOEpatents

Corman, Gregory Scot; Luthra, Krishan Lal

2002-01-01

A fiber-reinforced silicon-silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon-silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Silicon-doped boron nitride coated fibers in silicon melt infiltrated composites

DOEpatents

Corman, Gregory Scot; Luthra, Krishan Lal

1999-01-01

A fiber-reinforced silicon--silicon carbide matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is produced. The invention also provides a method for protecting the reinforcing fibers in the silicon--silicon carbide matrix composites by coating the fibers with a silicon-doped boron nitride coating.

Silicone elastomers capable of large isotropic dimensional change

DOEpatents

Lewicki, James; Worsley, Marcus A.

2017-07-18

Described herein is a highly effective route towards the controlled and isotropic reduction in size-scale, of complex 3D structures using silicone network polymer chemistry. In particular, a class of silicone structures were developed that once patterned and cured can `shrink` micron scale additive manufactured and lithographically patterned structures by as much as 1 order of magnitude while preserving the dimensions and integrity of these parts. This class of silicone materials is compatible with existing additive manufacture and soft lithographic fabrication processes and will allow access to a hitherto unobtainable dimensionality of fabrication.

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals.

PubMed

Diroll, Benjamin T; Schramke, Katelyn S; Guo, Peijun; Kortshagen, Uwe R; Schaller, Richard D

2017-10-11

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27%, and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

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

NASA Technical Reports Server (NTRS)

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

1986-01-01

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

Hydrogenated amorphous silicon formation by flux control and hydrogen effects on the growth mechanism

NASA Astrophysics Data System (ADS)

Toyoda, H.; Sugai, H.; Kato, K.; Yoshida, A.; Okuda, T.

1986-06-01

The composition of particle flux to deposit hydrogenated amorphous silicon films in a glow discharge is controlled by a combined electrostatic-magnetic deflection technique. As a result, the films are formed firstly without hydrogen ion flux, secondly by neutral flux only, and thirdly by all species fluxes. Comparison of these films reveals the significant role of hydrogen in the surface reactions. Hydrogen breaks the Si-Si bond, decreases the sticking probability of the Si atom, and replaces the SiH bond by a SiH2 bond to increase the hydrogen content of the films.

Heterogeneous silicon mesostructures for lipid-supported bioelectric interfaces

PubMed Central

Jiang, Yuanwen; Carvalho-de-Souza, João L.; Wong, Raymond C. S.; Luo, Zhiqiang; Isheim, Dieter; Zuo, Xiaobing; Nicholls, Alan W.; Jung, Il Woong; Yue, Jiping; Liu, Di-Jia; Wang, Yucai; De Andrade, Vincent; Xiao, Xianghui; Navrazhnykh, Luizetta; Weiss, Dara E.; Wu, Xiaoyang; Seidman, David N.; Bezanilla, Francisco; Tian, Bozhi

2017-01-01

Silicon-based materials have widespread application as biophysical tools and biomedical devices. Here we introduce a biocompatible and degradable mesostructured form of silicon with multiscale structural and chemical heterogeneities. The material was synthesized using mesoporous silica as a template through a chemical-vapor-deposition process. It has an amorphous atomic structure, an ordered nanowire-based framework, and random submicrometre voids, and shows an average Young’s modulus that is 2–3 orders of magnitude smaller than that of single crystalline silicon. In addition, we used the heterogeneous silicon mesostructures to design a lipid-bilayer-supported bioelectric interface that is remotely controlled and temporally transient, and that permits non-genetic and subcellular optical modulation of the electrophysiology dynamics in single dorsal root ganglia neurons. Our findings suggest that the biomimetic expansion of silicon into heterogeneous and deformable forms can open up opportunities in extracellular biomaterial or bioelectric systems. PMID:27348576

Revealing unobserved factors underlying cortical activity with a rectified latent variable model applied to neural population recordings.

PubMed

Whiteway, Matthew R; Butts, Daniel A

2017-03-01

The activity of sensory cortical neurons is not only driven by external stimuli but also shaped by other sources of input to the cortex. Unlike external stimuli, these other sources of input are challenging to experimentally control, or even observe, and as a result contribute to variability of neural responses to sensory stimuli. However, such sources of input are likely not "noise" and may play an integral role in sensory cortex function. Here we introduce the rectified latent variable model (RLVM) in order to identify these sources of input using simultaneously recorded cortical neuron populations. The RLVM is novel in that it employs nonnegative (rectified) latent variables and is much less restrictive in the mathematical constraints on solutions because of the use of an autoencoder neural network to initialize model parameters. We show that the RLVM outperforms principal component analysis, factor analysis, and independent component analysis, using simulated data across a range of conditions. We then apply this model to two-photon imaging of hundreds of simultaneously recorded neurons in mouse primary somatosensory cortex during a tactile discrimination task. Across many experiments, the RLVM identifies latent variables related to both the tactile stimulation as well as nonstimulus aspects of the behavioral task, with a majority of activity explained by the latter. These results suggest that properly identifying such latent variables is necessary for a full understanding of sensory cortical function and demonstrate novel methods for leveraging large population recordings to this end. NEW & NOTEWORTHY The rapid development of neural recording technologies presents new opportunities for understanding patterns of activity across neural populations. Here we show how a latent variable model with appropriate nonlinear form can be used to identify sources of input to a neural population and infer their time courses. Furthermore, we demonstrate how these sources are

Silane coupling agent bearing a photoremovable succinimidyl carbonate for patterning amines on glass and silicon surfaces with controlled surface densities.

PubMed

Nakayama, Hidekazu; Nakanishi, Jun; Shimizu, Takahiro; Yoshino, Yutaro; Iwai, Hideo; Kaneko, Shingo; Horiike, Yasuhiro; Yamaguchi, Kazuo

2010-03-01

Patterned immobilization of synthetic and biological ligands on material surfaces with controlled surface densities is important for various bioanalytical and cell biological purposes. This paper describes the synthesis, characterization, and application of a novel silane coupling agent bearing a photoremovable succinimidyl carbonate, which enables the photopatterning of various primary amines on glass and silicon surfaces. The silane coupling agent is 1-[5-methoxy-2-nitro-4-(3-trimethoxysilylpropyloxy)phenyl]ethyl N-succinimidyl carbonate. The distinct feature of this molecule is that it has a photocleavable 2-nitrobenzyl switch between a trimethoxysilyl group and a succinimidyl carbonate, each reactive to the hydroxy groups of inorganic oxides and primary amines. Based on this molecular design, the compound allows for the one-step introduction of succinimidyl carbonates onto the surface of glass and silicon, immobilization of primary amines, and region-selective and dose-dependent release of the amines by near-UV irradiation. Therefore, we were able to pattern amine ligands on the substrates in given surface densities and arbitrary geometries by controlling the doses and regions of photoirradiation. These features were verified by UV-vis spectroscopy, contact angle measurements, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ellipsometry, and atomic force microscopy (AFM). The compound was applied to form a chemical density gradient of amino-biotin on a silicon substrate in a range of 0.87-0.12 chains/nm(2) by controlling photoirradiation under a standard fluorescence microscope. Furthermore, we also succeeded in forming a chemical density gradient at a lower surface density range (0.15-0.011 chains/nm(2)) on the substrate by diluting the feed amino-biotin with an inert control amine.

Silicon nitride/silicon carbide composite densified materials prepared using composite powders

DOEpatents

Dunmead, S.D.; Weimer, A.W.; Carroll, D.F.; Eisman, G.A.; Cochran, G.A.; Susnitzky, D.W.; Beaman, D.R.; Nilsen, K.J.

1997-07-01

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.

Silicon carbide-silicon composite having improved oxidation resistance and method of making

NASA Technical Reports Server (NTRS)

Wang, Hongyu (Inventor); Luthra, Krishan Lal (Inventor)

1999-01-01

A Silicon carbide-silicon matrix composite having improved oxidation resistance at high temperatures in dry or water-containing environments is provided. A method is given for sealing matrix cracks in situ in melt infiltrated silicon carbide-silicon matrix composites. The composite cracks are sealed by the addition of various additives, such as boron compounds, into the melt infiltrated silicon carbide-silicon matrix.

[Effect of silicon coating on bonding strength of ceramics and titanium].

PubMed

Zhou, Shu; Wang, Yu; Zhang, Fei-Min; Guang, Han-Bing

2009-06-01

This study investigated the effect of silicon coating (SiO2) by solution-gelatin (Sol-Gel) technology on bonding strength of titanium and ceramics. Sixteen pure titanium specimens with the size of 25 mm x 3 mm x 0.5 mm were divided into two groups (n=8), test group was silicon coated by Sol-Gel technology, the other one was control group. The middle area of the samples were veneered with Vita Titankeramik system, the phase composition of two specimens were characterized by X-ray diffraction (XRD). The bonding strength of titanium/porcelain was evaluated using three-point bending test. The interface of titanium and porcelain and fractured titanium surface were investigated by scanning electron microscope (SEM) with energy depressive spectrum (EDS). Contents of surface silicon increased after modification with silicon coated by Sol-Gel technology. The mean bonding strength of test group and control group were (37.768 +/- 0.777) MPa and (29.483 +/- 1.007) MPa. There was a statistically significant difference (P=0.000) between them. The bonded ceramic boundary of test group was wider than control group. Silicon coating by Sol-Gel technology was significant in improving bonding strength of titanium/Vita Titankeramik system.

Thin film silicon by a microwave plasma deposition technique: Growth and devices, and, interface effects in amorphous silicon/crystalline silicon solar cells

NASA Astrophysics Data System (ADS)

Jagannathan, Basanth

Thin film silicon (Si) was deposited by a microwave plasma CVD technique, employing double dilution of silane, for the growth of low hydrogen content Si films with a controllable microstructure on amorphous substrates at low temperatures (<400sp°C). The double dilution was achieved by using a Ar (He) carrier for silane and its subsequent dilution by Hsb2. Structural and electrical properties of the films have been investigated over a wide growth space (temperature, power, pressure and dilution). Amorphous Si films deposited by silane diluted in He showed a compact nature and a hydrogen content of ˜8 at.% with a photo/dark conductivity ratio of 10sp4. Thin film transistors (W/L = 500/25) fabricated on these films, showed an on/off ratio of ˜10sp6 and a low threshold voltage of 2.92 volts. Microcrystalline Si films with a high crystalline content (˜80%) were also prepared by this technique. Such films showed a dark conductivity ˜10sp{-6} S/cm, with a conduction activation energy of 0.49 eV. Film growth and properties have been compared for deposition in Ar and He carrier systems and growth models have been proposed. Low temperature junction formation by undoped thin film silicon was examined through a thin film silicon/p-type crystalline silicon heterojunctions. The thin film silicon layers were deposited by rf glow discharge, dc magnetron sputtering and microwave plasma CVD. The hetero-interface was identified by current transport analysis and high frequency capacitance methods as the key parameter controlling the photovoltaic (PV) response. The effect of the interface on the device properties (PV, junction, and carrier transport) was examined with respect to modifications created by chemical treatment, type of plasma species, their energy and film microstructure interacting with the substrate. Thermally stimulated capacitance was used to determine the interfacial trap parameters. Plasma deposition of thin film silicon on chemically clean c-Si created electron

Inward rectifier potassium current (I K1) and Kir2 composition of the zebrafish (Danio rerio) heart.

PubMed

Hassinen, Minna; Haverinen, Jaakko; Hardy, Matt E; Shiels, Holly A; Vornanen, Matti

2015-12-01

Electrophysiological properties and molecular background of the zebrafish (Danio rerio) cardiac inward rectifier current (IK1) were examined. Ventricular myocytes of zebrafish have a robust (-6.7 ± 1.2 pA pF(-1) at -120 mV) strongly rectifying and Ba(2+)-sensitive (IC50 = 3.8 μM) IK1. Transcripts of six Kir2 channels (drKir2.1a, drKir2.1b, drKir2.2a, drKir2.2b, drKir2.3, and drKir2.4) were expressed in the zebrafish heart. drKir2.4 and drKir2.2a were the dominant isoforms in both the ventricle (92.9 ± 1.5 and 6.3 ± 1.5%) and the atrium (28.9 ± 2.9 and 64.7 ± 3.0%). The remaining four channels comprised together less than 1 and 7 % of the total transcripts in ventricle and atrium, respectively. The four main gene products (drKir2.1a, drKir2.2a, drKir2.2b, drKir2.4) were cloned, sequenced, and expressed in HEK cells for electrophysiological characterization. drKir2.1a was the most weakly rectifying (passed more outward current) and drKir2.2b the most strongly rectifying (passed less outward current) channel, whilst drKir2.2a and drKir2.4 were intermediate between the two. In regard to sensitivity to Ba(2+) block, drKir2.4 was the most sensitive (IC50 = 1.8 μM) and drKir2.1a the least sensitive channel (IC50 = 132 μM). These findings indicate that the Kir2 isoform composition of the zebrafish heart markedly differs from that of mammalian hearts. Furthermore orthologous Kir2 channels (Kir2.1 and Kir2.4) of zebrafish and mammals show striking differences in Ba(2+)-sensitivity. Structural and functional differences needs to be taken into account when zebrafish is used as a model for human cardiac electrophysiology, cardiac diseases, and in screening cardioactive substances.

Novel duplex vapor-electrochemical method for silicon solar cells

NASA Technical Reports Server (NTRS)

Kapur, V. K.; Nanis, L.; Sanjurjo, A.

1977-01-01

Silicon was produced by alternate pulse feeding of the reactants SiF4 gas and liquid sodium. The average temperature in the reactor could be controlled, by regulating the amount of reactant in each pulse. Silicon tetrafluoride gas was analyzed by mass spectrometry to determine the nature and amount of contained volatile impurities which included silicon oxyfluorides, sulfur oxyfluorides, and sulfur dioxide. Sodium metal was analyzed by emission spectrography, and it was found to contain only calcium and copper as impurities.

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

PubMed Central

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

2013-01-01

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

Activation of the Ca2+-sensing receptors increases currents through inward rectifier K+ channels via activation of phosphatidylinositol 4-kinase.

PubMed

Liu, Chung-Hung; Chang, Hsueh-Kai; Lee, Sue-Ping; Shieh, Ru-Chi

2016-11-01

Inward rectifier K + channels are important for maintaining normal electrical function in many cell types. The proper function of these channels requires the presence of membrane phosphoinositide 4,5-bisphosphate (PIP 2 ). Stimulation of the Ca 2+ -sensing receptor CaR, a pleiotropic G protein-coupled receptor, activates both G q/11 , which decreases PIP 2 , and phosphatidylinositol 4-kinase (PI-4-K), which, conversely, increases PIP 2 . How membrane PIP 2 levels are regulated by CaR activation and whether these changes modulate inward rectifier K + are unknown. In this study, we found that activation of CaR by the allosteric agonist, NPSR568, increased inward rectifier K + current (I K1 ) in guinea pig ventricular myocytes and currents mediated by Kir2.1 channels exogenously expressed in HEK293T cells with a similar sensitivity. Moreover, using the fluorescent PIP 2 reporter tubby-R332H-cYFP to monitor PIP 2 levels, we found that CaR activation in HEK293T cells increased membrane PIP 2 concentrations. Pharmacological studies showed that both phospholipase C (PLC) and PI-4-K are activated by CaR stimulation with the latter played a dominant role in regulating membrane PIP 2 and, thus, Kir currents. These results provide the first direct evidence that CaR activation upregulates currents through inward rectifier K + channels by accelerating PIP 2 synthesis. The regulation of I K1 plays a critical role in the stability of the electrical properties of many excitable cells, including cardiac myocytes and neurons. Further, synthetic allosteric modulators that increase CaR activity have been used to treat hyperparathyroidism, and negative CaR modulators are of potential importance in the treatment of osteoporosis. Thus, our results provide further insight into the roles played by CaR in the cardiovascular system and are potentially valuable for heart disease treatment and drug safety.

Polycrystalline silicon study: Low-cost silicon refining technology prospects and semiconductor-grade polycrystalline silicon availability through 1988

NASA Technical Reports Server (NTRS)

Costogue, E. N.; Ferber, R.; Lutwack, R.; Lorenz, J. H.; Pellin, R.

1984-01-01

Photovoltaic arrays that convert solar energy into electrical energy can become a cost effective bulk energy generation alternative, provided that an adequate supply of low cost materials is available. One of the key requirements for economic photovoltaic cells is reasonably priced silicon. At present, the photovoltaic industry is dependent upon polycrystalline silicon refined by the Siemens process primarily for integrated circuits, power devices, and discrete semiconductor devices. This dependency is expected to continue until the DOE sponsored low cost silicon refining technology developments have matured to the point where they are in commercial use. The photovoltaic industry can then develop its own source of supply. Silicon material availability and market pricing projections through 1988 are updated based on data collected early in 1984. The silicon refining industry plans to meet the increasing demands of the semiconductor device and photovoltaic product industries are overviewed. In addition, the DOE sponsored technology research for producing low cost polycrystalline silicon, probabilistic cost analysis for the two most promising production processes for achieving the DOE cost goals, and the impacts of the DOE photovoltaics program silicon refining research upon the commercial polycrystalline silicon refining industry are addressed.

Starting Silicon-Ribbon Growth Automatically

NASA Technical Reports Server (NTRS)

Mchugh, J. P.

1984-01-01

Semiautomatic system starts growth of silicon sheets more reliably than system with purely manual control. Control signals for starting sheetcrystal growth consist of ramps (during which signal changes linearly from one value to another over preset time interval) and soaks (during which signal remains constant). Ramps and soaks for best temperature and pulling speed determined by experimentation.

Ion beam figuring of silicon aspheres

NASA Astrophysics Data System (ADS)

Demmler, Marcel; Zeuner, Michael; Luca, Alfonz; Dunger, Thoralf; Rost, Dirk; Kiontke, Sven; Krüger, Marcus

2011-03-01

Silicon lenses are widely used for infrared applications. Especially for portable devices the size and weight of the optical system are very important factors. The use of aspherical silicon lenses instead of spherical silicon lenses results in a significant reduction of weight and size. The manufacture of silicon lenses is more challenging than the manufacture of standard glass lenses. Typically conventional methods like diamond turning, grinding and polishing are used. However, due to the high hardness of silicon, diamond turning is very difficult and requires a lot of experience. To achieve surfaces of a high quality a polishing step is mandatory within the manufacturing process. Nevertheless, the required surface form accuracy cannot be achieved through the use of conventional polishing methods because of the unpredictable behavior of the polishing tools, which leads to an unstable removal rate. To overcome these disadvantages a method called Ion Beam Figuring can be used to manufacture silicon lenses with high surface form accuracies. The general advantage of the Ion Beam Figuring technology is a contactless polishing process without any aging effects of the tool. Due to this an excellent stability of the removal rate without any mechanical surface damage is achieved. The related physical process - called sputtering - can be applied to any material and is therefore also applicable to materials of high hardness like Silicon (SiC, WC). The process is realized through the commercially available ion beam figuring system IonScan 3D. During the process, the substrate is moved in front of a focused broad ion beam. The local milling rate is controlled via a modulated velocity profile, which is calculated specifically for each surface topology in order to mill the material at the associated positions to the target geometry. The authors will present aspherical silicon lenses with very high surface form accuracies compared to conventionally manufactured lenses.

Latchup in CMOS devices from heavy ions

NASA Technical Reports Server (NTRS)

Soliman, K.; Nichols, D. K.

1983-01-01

It is noted that complementary metal oxide semiconductor (CMOS) microcircuits are inherently latchup prone. The four-layer n-p-n-p structures formed from the parasitic pnp and npn transistors make up a silicon controlled rectifier. If properly biased, this rectifier may be triggered 'ON' by electrical transients, ionizing radiation, or a single heavy ion. This latchup phenomenon might lead to a loss of functionality or device burnout. Results are presented from tests on 19 different device types from six manufacturers which investigate their latchup sensitivity with argon and krypton beams. The parasitic npnp paths are identified in general, and a qualitative rationale is given for latchup susceptibility, along with a latchup cross section for each type of device. Also presented is the correlation between bit-flip sensitivity and latchup susceptibility.

Lithographically defined few-electron silicon quantum dots based on a silicon-on-insulator substrate

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

Horibe, Kosuke; Oda, Shunri; Kodera, Tetsuo, E-mail: kodera.t.ac@m.titech.ac.jp

2015-02-23

Silicon quantum dot (QD) devices with a proximal single-electron transistor (SET) charge sensor have been fabricated in a metal-oxide-semiconductor structure based on a silicon-on-insulator substrate. The charge state of the QDs was clearly read out using the charge sensor via the SET current. The lithographically defined small QDs enabled clear observation of the few-electron regime of a single QD and a double QD by charge sensing. Tunnel coupling on tunnel barriers of the QDs can be controlled by tuning the top-gate voltages, which can be used for manipulation of the spin quantum bit via exchange interaction between tunnel-coupled QDs. Themore » lithographically defined silicon QD device reported here is technologically simple and does not require electrical gates to create QD confinement potentials, which is advantageous for the integration of complicated constructs such as multiple QD structures with SET charge sensors for the purpose of spin-based quantum computing.« less

Perceived Harm of Online Drug-Encouraging Messages: Third-Person Effect and Adolescents' Support for Rectifying Measures

ERIC Educational Resources Information Center

Leung, Wan Chi; Lo, Ven-Hwei

2015-01-01

This study examines third-person perceptions (TPP) of two types of online messages--antisocial messages that encourage drug abuse and prosocial messages in the youth anti-drug campaign--and their relationship with support for three types of rectifying measures: restrictive, corrective, and promotional. A survey of 778 secondary school students…

Speed control for synchronous motors

NASA Technical Reports Server (NTRS)

Packard, H.; Schott, J.

1981-01-01

Feedback circuit controls fluctuations in speed of synchronous ac motor. Voltage proportional to phase angle is developed by phase detector, rectified, amplified, compared to threshold, and reapplied positively or negatively to motor excitation circuit. Speed control reduces wow and flutter of audio turntables and tape recorders, and enhances hunting in gyroscope motors.

Fabrication of novel silicone capsules with tunable mechanical properties by microfluidic techniques.

PubMed

Vilanova, Neus; Rodríguez-Abreu, Carlos; Fernández-Nieves, Alberto; Solans, Conxita

2013-06-12

A novel approach for the synthesis of silicone capsules using double W/O/W emulsions as templates is introduced. The low viscosity of the silicone precursors enables the use of microfluidic techniques to accurately control the size and morphology of the double emulsion droplets, which after cross-linking result in the desired monodisperse silicone capsules. Their shell thickness can be finely tuned, which in turn allows control over their permeability and mechanical properties; the latter are particularly important in a variety of practical applications where the capsules are subjected to large external forces. The potential of these capsules for controlled release is also demonstrated using a model hydrophilic substance.

Intravitreal properties of porous silicon photonic crystals

PubMed Central

Cheng, L; Anglin, E; Cunin, F; Kim, D; Sailor, M J; Falkenstein, I; Tammewar, A; Freeman, W R

2009-01-01

Aim To determine the suitability of porous silicon photonic crystals for intraocular drug-delivery. Methods A rugate structure was electrochemically etched into a highly doped p-type silicon substrate to create a porous silicon film that was subsequently removed and ultrasonically fractured into particles. To stabilise the particles in aqueous media, the silicon particles were modified by surface alkylation (using thermal hydrosilylation) or by thermal oxidation. Unmodified particles, hydrosilylated particles and oxidised particles were injected into rabbit vitreous. The stability and toxicity of each type of particle were studied by indirect ophthalmoscopy, biomicroscopy, tonometry, electroretinography (ERG) and histology. Results No toxicity was observed with any type of the particles during a period of >4 months. Surface alkylation led to dramatically increased intravitreal stability and slow degradation. The estimated vitreous half-life increased from 1 week (fresh particles) to 5 weeks (oxidised particles) and to 16 weeks (hydrosilylated particles). Conclusion The porous silicon photonic crystals showed good biocompatibility and may be used as an intraocular drug-delivery system. The intravitreal injectable porous silicon photonic crystals may be engineered to host a variety of therapeutics and achieve controlled drug release over long periods of time to treat chronic vitreoretinal diseases. PMID:18441177

Heterogeneous silicon mesostructures for lipid-supported bioelectric interfaces

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

Jiang, Yuanwen; Carvalho-de-Souza, João L.; Wong, Raymond C. S.

Silicon-based materials have widespread application as biophysical tools and biomedical devices. Here we introduce a biocompatible and degradable mesostructured form of silicon with multi-scale structural and chemical heterogeneities. The material was synthesized using mesoporous silica as a template through a chemical vapour deposition process. It has an amorphous atomic structure, an ordered nanowire-based framework and random submicrometre voids, and shows an average Young’s modulus that is 2–3 orders of magnitude smaller than that of single-crystalline silicon. In addition, we used the heterogeneous silicon mesostructures to design a lipid-bilayer-supported bioelectric interface that is remotely controlled and temporally transient, and that permitsmore » non-genetic and subcellular optical modulation of the electrophysiology dynamics in single dorsal root ganglia neurons. Our findings suggest that the biomimetic expansion of silicon into heterogeneous and deformable forms can open up opportunities in extracellular biomaterial or bioelectric systems.« less

G-protein-coupled inward rectifier potassium channels involved in corticostriatal presynaptic modulation.

PubMed

Meneses, David; Mateos, Verónica; Islas, Gustavo; Barral, Jaime

2015-09-01

Presynaptic modulation has been associated mainly with calcium channels but recent data suggests that inward rectifier potassium channels (K(IR)) also play a role. In this work we set to characterize the role of presynaptic K(IR) channels in corticostriatal synaptic transmission. We elicited synaptic potentials in striatum by stimulating cortical areas and then determined the synaptic responses of corticostriatal synapsis by using paired pulse ratio (PPR) in the presence and absence of several potassium channel blockers. Unspecific potassium channels blockers Ba(2+) and Cs(+) reduced the PPR, suggesting that these channels are presynaptically located. Further pharmacological characterization showed that application of tertiapin-Q, a specific K(IR)3 channel family blocker, also induced a reduction of PPR, suggesting that K(IR)3 channels are present at corticostriatal terminals. In contrast, exposure to Lq2, a specific K(IR)1.1 inward rectifier potassium channel, did not induce any change in PPR suggesting the absence of these channels in the presynaptic corticostriatal terminals. Our results indicate that K(IR)3 channels are functionally expressed at the corticostriatal synapses, since blockage of these channels result in PPR decrease. Our results also help to explain how synaptic activity may become sensitive to extracellular signals mediated by G-protein coupled receptors. A vast repertoire of receptors may influence neurotransmitter release in an indirect manner through regulation of K(IR)3 channels. © 2015 Wiley Periodicals, Inc.

Baseline tests of the EVA change-of-pace coupe electric passenger vehicle

NASA Technical Reports Server (NTRS)

Bozek, J. M.; Maslowski, E. A.; Dustin, M. O.

1977-01-01

The EVA Change-of-Pace Coupe, is an electric passenger vehicle, to characterize the state-of-the-art of electric vehicles. The EVA Change-of-Pace Coupe is a four passenger sedan that has been coverted to an electric vehicle. It is powered by twenty 6 volt traction batteries through a silicon controlled rectifier chopper controller actuated by a foot throttle to change the voltage applied to the series wound, direct current motor. Braking is accomplished with a vacuum assist hydraulic braking system. Regenerative braking is also provided.

Electrophysiological characterization of 14-benzoyltalatisamine, a selective blocker of the delayed rectifier K+ channel found in virtual screening.

PubMed

Song, Ming-Ke; Liu, Hong; Jiang, Hua-Liang; Yue, Jian-Min; Hu, Guo-Yuan

2006-02-15

14-Benzoyltalatisamine is a potent and selective blocker of the delayed rectifier K+ channel found in a computational virtual screening study. The compound was found to block the K+ channel from the extracellular side. However, it is unclear whether 14-benzoyltalatisamine shares the same block mechanism with tetraethylammonium (TEA). In order to elucidate how the hit compound found by the virtual screening interacts with the outer vestibule of the K+ channel, the effects of 14-benzoyltalatisamine and TEA on the delayed rectifier K+ current of rat dissociated hippocampal neurons were compared using whole-cell voltage-clamp recording. External application of 14-benzoyltalatisamine and TEA reversibly inhibited the current with IC50 values of 10.1+/-2.2 microM and 1.05+/-0.21 mM, respectively. 14-Benzoyltalatisamine exerted voltage-dependent inhibition, markedly accelerated the decay of the current, and caused a significant hyperpolarizing shift of the steady-state activation curve, whereas TEA caused voltage-independent inhibition, without affecting the kinetic parameters of the current. The blockade by 14-benzoyltalatisamine, but not by TEA, was significantly diminished in a high K+ (60 mM) external solution. The potency of 14-benzoyltalatisamine was markedly reduced in the presence of 15 mM TEA. The results suggest that 14-benzoyltalatisamine bind to the external pore entry of the delayed rectifier K+ channel with partial insertion into the selectivity filter, which is in conformity with that predicted by the molecular docking model in the virtual screening.

Discovery of talatisamine as a novel specific blocker for the delayed rectifier K+ channels in rat hippocampal neurons.

PubMed

Song, M-K; Liu, H; Jiang, H-L; Yue, J-M; Hu, G-Y; Chen, H-Z

2008-08-13

Blocking specific K+ channels has been proposed as a promising strategy for the treatment of neurodegenerative diseases. Using a computational virtual screening approach and electrophysiological testing, we found four Aconitum alkaloids are potent blockers of the delayed rectifier K+ channel in rat hippocampal neurons. In the present study, we first tested the action of the four alkaloids on the voltage-gated K+, Na+ and Ca2+ currents in rat hippocampal neurons, and then identified that talatisamine is a specific blocker for the delayed rectifier K+ channel. External application of talatisamine reversibly inhibited the delayed rectifier K+ current (IK) with an IC50 value of 146.0+/-5.8 microM in a voltage-dependent manner, but exhibited very slight blocking effect on the voltage-gated Na+ and Ca2+ currents even at the high concentration of 1-3 mM. Moreover, talatisamine exerted a significant hyperpolarizing shift of the steady-state activation, but did not influence the steady state inactivation of IK and its recovery from inactivation, suggesting that talatisamine had no allosteric action on IK channel and was a pure blocker binding to the external pore entry of the channel. Our present study made the first discovery of potent and specific IK channel blocker from Aconitum alkaloids. It has been argued that suppressing K+ efflux by blocking IK channel may be favorable for Alzheimer's disease therapy. Talatisamine can therefore be considered as a leading compound worthy of further investigations.

Human Myoblast Fusion Requires Expression of Functional Inward Rectifier Kir2.1 Channels

PubMed Central

Fischer-Lougheed, Jacqueline; Liu, Jian-Hui; Espinos, Estelle; Mordasini, David; Bader, Charles R.; Belin, Dominique; Bernheim, Laurent

2001-01-01

Myoblast fusion is essential to skeletal muscle development and repair. We have demonstrated previously that human myoblasts hyperpolarize, before fusion, through the sequential expression of two K+ channels: an ether-à-go-go and an inward rectifier. This hyperpolarization is a prerequisite for fusion, as it sets the resting membrane potential in a range at which Ca2+ can enter myoblasts and thereby trigger fusion via a window current through α1H T channels. PMID:11352930

The Efficacy of a Silicone Sheet in Postoperative Scar Management.

PubMed

Kim, Jin Sam; Hong, Joon Pio; Choi, Jong Woo; Seo, Dong Kyo; Lee, Eun Sook; Lee, Ho Seong

2016-09-01

Silicone gel sheeting has been introduced to prevent scarring, but objective evidence for its usefulness in scar healing is limited. Therefore, the authors' objective was to examine the effectiveness of silicone gel sheeting by randomly applying it to only unilateral scars from a bilateral hallux valgus surgery with symmetrical closure. In a prospective randomized, blinded, intraindividual comparison study, the silicone gel sheeting was applied to 1 foot of a hallux valgus incision scar (an experiment group) for 12 weeks upon removal of the stitches, whereas the symmetrical scar from the other foot was left untreated (a control group). The scars were evaluated at 4 and 12 weeks after the silicon sheet application. The Vancouver Scar Scale was used to measure the vascularity, pigmentation, pliability, height, and length of the scars. Adverse effects were also evaluated, and they included pain, itchiness, rash, erythema, and skin softening. At weeks 4 and 12, the experiment group scored significantly better on the Vancouver Scar Scale in all items, except length (P < .05 for all except the length of scar), compared with the control group. In all items, adverse effects of the experiment group were significantly lower than those of the control group at week 12, suggesting that direct attachment of the silicone sheet does not cause adverse effects (P < .05). To the authors' knowledge, this is one of the first models to minimize bias related to scar evaluation by using symmetrical scars. The early silicone sheet application did show a significant improvement in prevention of postoperative scarring.

Single crystal functional oxides on silicon

PubMed Central

Bakaul, Saidur Rahman; Serrao, Claudy Rayan; Lee, Michelle; Yeung, Chun Wing; Sarker, Asis; Hsu, Shang-Lin; Yadav, Ajay Kumar; Dedon, Liv; You, Long; Khan, Asif Islam; Clarkson, James David; Hu, Chenming; Ramesh, Ramamoorthy; Salahuddin, Sayeef

2016-01-01

Single-crystalline thin films of complex oxides show a rich variety of functional properties such as ferroelectricity, piezoelectricity, ferro and antiferromagnetism and so on that have the potential for completely new electronic applications. Direct synthesis of such oxides on silicon remains challenging because of the fundamental crystal chemistry and mechanical incompatibility of dissimilar interfaces. Here we report integration of thin (down to one unit cell) single crystalline, complex oxide films onto silicon substrates, by epitaxial transfer at room temperature. In a field-effect transistor using a transferred lead zirconate titanate layer as the gate insulator, we demonstrate direct reversible control of the semiconductor channel charge with polarization state. These results represent the realization of long pursued but yet to be demonstrated single-crystal functional oxides on-demand on silicon. PMID:26853112

Porous silicon technology for integrated microsystems

NASA Astrophysics Data System (ADS)

Wallner, Jin Zheng

With the development of micro systems, there is an increasing demand for integrable porous materials. In addition to those conventional applications, such as filtration, wicking, and insulating, many new micro devices, including micro reactors, sensors, actuators, and optical components, can benefit from porous materials. Conventional porous materials, such as ceramics and polymers, however, cannot meet the challenges posed by micro systems, due to their incompatibility with standard micro-fabrication processes. In an effort to produce porous materials that can be used in micro systems, porous silicon (PS) generated by anodization of single crystalline silicon has been investigated. In this work, the PS formation process has been extensively studied and characterized as a function of substrate type, crystal orientation, doping concentration, current density and surfactant concentration and type. Anodization conditions have been optimized for producing very thick porous silicon layers with uniform pore size, and for obtaining ideal pore morphologies. Three different types of porous silicon materials: meso porous silicon, macro porous silicon with straight pores, and macro porous silicon with tortuous pores, have been successfully produced. Regular pore arrays with controllable pore size in the range of 2mum to 6mum have been demonstrated as well. Localized PS formation has been achieved by using oxide/nitride/polysilicon stack as masking materials, which can withstand anodization in hydrofluoric acid up to twenty hours. A special etching cell with electrolytic liquid backside contact along with two process flows has been developed to enable the fabrication of thick macro porous silicon membranes with though wafer pores. For device assembly, Si-Au and In-Au bonding technologies have been developed. Very low bonding temperature (˜200°C) and thick/soft bonding layers (˜6mum) have been achieved by In-Au bonding technology, which is able to compensate the potentially

Feasibility of using mixtures of silicone elastomers and silicone oils to model the mechanical behaviour of biological tissues

PubMed Central

Ahmadzadeh, S Mohammad Hassan

2014-01-01

Mixtures of silicone elastomer and silicone oil were prepared and the values of their Young’s moduli, E, determined in compression. The mixtures had volume fractions, ϕ, of silicone oil in the range of 0–0.73. Measurements were made, under displacement control, for strain rates, ε·, in the range of 0.04–3.85 s−1. The behaviour of E as a function of ϕ and ε· was investigated using a response surface model. The effects of the two variables were independent for the silicones used in this investigation. As a result, the dependence of E values (measured in MPa) on ϕ and ε· (s−1) could be represented by E=0.57−0.75ϕ+0.01loge(ε·). This means that these silicones can be mixed to give materials with E values in the range of about 0.02–0.57 MPa, which includes E values for many biological tissues. Thus, the mixtures can be used for making models for training health-care professionals and may be useful in some research applications as model tissues that do not exhibit biological variability. PMID:24951628

Kinetics of thermal donor generation in silicon

NASA Technical Reports Server (NTRS)

Mao, B.-Y.; Lagowski, J.; Gatos, H. C.

1984-01-01

The generation kinetics of thermal donors at 450 C in Czochralski-grown silicon was found to be altered by high-temperature preannealing (e.g., 1100 C for 30 min). Thus, when compared with as-grown Si, high-temperature preannealed material exhibits a smaller concentration of generated thermal donors and a faster thermal donor saturation. A unified mechanism of nucleation and oxygen diffusion-controlled growth (based on solid-state plate transformation theory) is proposed to account for generation kinetics of thermal donors at 450 C, in as-grown and high-temperature preannealed Czochralski silicon crystals. This mechanism is consistent with the main features of the models which have been proposed to explain the formation of oxygen thermal donors in silicon.

Method for Molding Structural Parts Utilizing Modified Silicone Rubber

NASA Technical Reports Server (NTRS)

Weiser, Erik S. (Inventor); Baucom, Robert M. (Inventor); Snoha, John J. (Inventor)

1998-01-01

This invention improves upon a method for molding structural parts from preform material. Preform material to be used for the part is provided. A silicone rubber composition containing entrained air voids is prepared. The silicone rubber and preform material assembly is situated within a rigid mold cavity used to shape the preform material to die desired shape. The entire assembly is heated in a standard heating device so that the thermal expansion of the silicone rubber exerts the pressure necessary to force the preform material into contact with the mold container. The introduction of discrete air voids into the silicone rubber allows for accurately controlled pressure application on the preform material at the cure temperature.

Method of forming silicon structures with selectable optical characteristics

NASA Technical Reports Server (NTRS)

Fathauer, Robert W. (Inventor); Schowalter, Leo (Inventor)

1993-01-01

Silicon and metal are coevaporated onto a silicon substrate in a molecular beam epitaxy system with a larger than stoichiometric amount of silicon so as to epitaxially grow particles of metal silicide embedded in a matrix of single crystal epitaxially grown silicon. The particles interact with incident photons by resonant optical absorption at the surface plasmon resonance frequency. Controlling the substrate temperature and deposition rate and time allows the aspect ratio of the particles to be tailored to desired wavelength photons and polarizations. The plasmon energy may decay as excited charge carriers or phonons, either of which can be monitored to indicate the amount of incident radiation at the selected frequency and polarization.

Effect of Silicon in U-10Mo Alloy

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

Kautz, Elizabeth J.; Devaraj, Arun; Kovarik, Libor

2017-08-31

This document details a method for evaluating the effect of silicon impurity content on U-10Mo alloys. Silicon concentration in U-10Mo alloys has been shown to impact the following: volume fraction of precipitate phases, effective density of the final alloy, and 235-U enrichment in the gamma-UMo matrix. This report presents a model for calculating these quantities as a function of Silicon concentration, which along with fuel foil characterization data, will serve as a reference for quality control of the U-10Mo final alloy Si content. Additionally, detailed characterization using scanning electron microscope imaging, transmission electron microscope diffraction, and atom probe tomography showedmore » that Silicon impurities present in U-10Mo alloys form a Si-rich precipitate phase.« less

Photoluminescence of Porous Silicon-Zinc Oxide Hybrid structures

NASA Astrophysics Data System (ADS)

Olenych, I. B.; Monastyrskii, L. S.; Luchechko, A. P.

2017-03-01

Arrays of ZnO nanostructures, which are optically transparent in the visible range, were grown on the surface of porous silicon by electrochemical deposition. Photoluminescence excitation and emission spectra of the obtained hybrid structures were investigated in 220-450 and 400-800 nm regions, respectively. It is established that multicolor emission is formed by combining the luminescence bands of porous silicon and zinc oxide. The possibility of controlling the photoluminescence spectra by changing the excitation energy is demonstrated. It is revealed that thermal annealing has an effect on the luminescent properties of porous silicon/zinc oxide hybrid structures. Thermal processing at 500°C leads to a sharp decrease of long-wavelength luminescence associated with porous silicon and to an increase of short-wavelength luminescence intensity related to zinc oxide.

Glass-silicon column

DOEpatents

Yu, Conrad M.

2003-12-30

A glass-silicon column that can operate in temperature variations between room temperature and about 450.degree. C. The glass-silicon column includes large area glass, such as a thin Corning 7740 boron-silicate glass bonded to a silicon wafer, with an electrode embedded in or mounted on glass of the column, and with a self alignment silicon post/glass hole structure. The glass/silicon components are bonded, for example be anodic bonding. In one embodiment, the column includes two outer layers of silicon each bonded to an inner layer of glass, with an electrode imbedded between the layers of glass, and with at least one self alignment hole and post arrangement. The electrode functions as a column heater, and one glass/silicon component is provided with a number of flow channels adjacent the bonded surfaces.

Light-induced negative differential resistance in gate-controlled graphene-silicon photodiode

NASA Astrophysics Data System (ADS)

Liu, Wei; Guo, Hongwei; Li, Wei; Wan, Xia; Bodepudi, Srikrishna Chanakya; Shehzad, Khurram; Xu, Yang

2018-05-01

In this letter, we investigated light-induced negative differential resistance (L-NDR) effects in a hybrid photodiode formed by a graphene-silicon (GS) junction and a neighboring graphene-oxide-Si (GOS) capacitor. We observed two distinct L-NDR effects originating from the gate-dependent surface recombination and the potential-well-induced confinement of photo-carriers in the GOS region. We verified this by studying the gate-controlled GS diode, which can distinguish the photocurrent from the GS region with that from the GOS region (gate). A large peak-to-valley ratio of up to 12.1 has been obtained for the L-NDR due to gate-dependent surface recombination. Such strong L-NDR effect provides an opportunity to further engineer the optoelectronic properties of GS junctions along with exploring its potential applications in photodetectors, photo-memories, and position sensitive devices.

Directed Atom-by-Atom Assembly of Dopants in Silicon.

PubMed

Hudak, Bethany M; Song, Jiaming; Sims, Hunter; Troparevsky, M Claudia; Humble, Travis S; Pantelides, Sokrates T; Snijders, Paul C; Lupini, Andrew R

2018-05-17

The ability to controllably position single atoms inside materials is key for the ultimate fabrication of devices with functionalities governed by atomic-scale properties. Single bismuth dopant atoms in silicon provide an ideal case study in view of proposals for single-dopant quantum bits. However, bismuth is the least soluble pnictogen in silicon, meaning that the dopant atoms tend to migrate out of position during sample growth. Here, we demonstrate epitaxial growth of thin silicon films doped with bismuth. We use atomic-resolution aberration-corrected imaging to view the as-grown dopant distribution and then to controllably position single dopants inside the film. Atomic-scale quantum-mechanical calculations corroborate the experimental findings. These results indicate that the scanning transmission electron microscope is of particular interest for assembling functional materials atom-by-atom because it offers both real-time monitoring and atom manipulation. We envision electron-beam manipulation of atoms inside materials as an achievable route to controllable assembly of structures of individual dopants.

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

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

Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals

DOE PAGES

Diroll, Benjamin T.; Schramke, Katelyn S.; Guo, Peijun; ...

2017-09-11

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Also, unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective massmore » at high effective hole temperatures lead to a sub-picosecond change of the dielectric function resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27% and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates sub-picosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting modulation of transmittance at telecommunications wavelengths. Lastly, the results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.« less

Vertical integration of high-Q silicon nitride microresonators into silicon-on-insulator platform.

PubMed

Li, Qing; Eftekhar, Ali A; Sodagar, Majid; Xia, Zhixuan; Atabaki, Amir H; Adibi, Ali

2013-07-29

We demonstrate a vertical integration of high-Q silicon nitride microresonators into the silicon-on-insulator platform for applications at the telecommunication wavelengths. Low-loss silicon nitride films with a thickness of 400 nm are successfully grown, enabling compact silicon nitride microresonators with ultra-high intrinsic Qs (~ 6 × 10(6) for 60 μm radius and ~ 2 × 10(7) for 240 μm radius). The coupling between the silicon nitride microresonator and the underneath silicon waveguide is based on evanescent coupling with silicon dioxide as buffer. Selective coupling to a desired radial mode of the silicon nitride microresonator is also achievable using a pulley coupling scheme. In this work, a 60-μm-radius silicon nitride microresonator has been successfully integrated into the silicon-on-insulator platform, showing a single-mode operation with an intrinsic Q of 2 × 10(6).

Direct Growth of Graphene on Silicon by Metal-Free Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Tai, Lixuan; Zhu, Daming; Liu, Xing; Yang, Tieying; Wang, Lei; Wang, Rui; Jiang, Sheng; Chen, Zhenhua; Xu, Zhongmin; Li, Xiaolong

2018-06-01

The metal-free synthesis of graphene on single-crystal silicon substrates, the most common commercial semiconductor, is of paramount significance for many technological applications. In this work, we report the growth of graphene directly on an upside-down placed, single-crystal silicon substrate using metal-free, ambient-pressure chemical vapor deposition. By controlling the growth temperature, in-plane propagation, edge-propagation, and core-propagation, the process of graphene growth on silicon can be identified. This process produces atomically flat monolayer or bilayer graphene domains, concave bilayer graphene domains, and bulging few-layer graphene domains. This work would be a significant step toward the synthesis of large-area and layer-controlled, high-quality graphene on single-crystal silicon substrates. [Figure not available: see fulltext.

RF Rectification on LAPD and NSTX: the relationship between rectified currents and potentials

NASA Astrophysics Data System (ADS)

Perkins, R. J.; Carter, T.; Caughman, J. B.; van Compernolle, B.; Gekelman, W.; Hosea, J. C.; Jaworski, M. A.; Kramer, G. J.; Lau, C.; Martin, E. H.; Pribyl, P.; Tripathi, S. K. P.; Vincena, S.

2017-10-01

RF rectification is a sheath phenomenon important in the fusion community for impurity injection, hot spot formation on plasma-facing components, modifications of the scrape-off layer, and as a far-field sink of wave power. The latter is of particular concern for the National Spherical Torus eXperiment (NSTX), where a substantial fraction of the fast-wave power is lost to the divertor along scrape-off layer field lines. To assess the relationship between rectified currents and rectified voltages, detailed experiments have been performed on the Large Plasma Device (LAPD). An electron current is measured flowing out of the antenna and into the limiters, consistent with RF rectification with a higher RF potential at the antenna. The scaling of this current with RF power will be presented. The limiters are also floated to inhibit this DC current; the impact of this change on plasma-potential and wave-field measurements will be shown. Comparison to data from divertor probes in NSTX will be made. These experiments on a flexible mid-sized experiment will provide insight and guidance into the effects of ICRF on the edge plasma in larger fusion experiments. Funded by the DOE OFES (DE-FC02-07ER54918 and DE-AC02-09CH11466), NSF (NSF- PHY 1036140), and the Univ. of California (12-LR- 237124).

Optimal Design of a Resonance-Based Voltage Boosting Rectifier for Wireless Power Transmission.

PubMed

Lim, Jaemyung; Lee, Byunghun; Ghovanloo, Maysam

2018-02-01

This paper presents the design procedure for a new multi-cycle resonance-based voltage boosting rectifier (MCRR) capable of delivering a desired amount of power to the load (PDL) at a designated high voltage (HV) through a loosely-coupled inductive link. This is achieved by shorting the receiver (Rx) LC-tank for several cycles to harvest and accumulate the wireless energy in the RX inductor before boosting the voltage by breaking the loop and transferring the energy to the load in a quarter cycle. By optimizing the geometries of the transmitter (Tx) and Rx coils and the number of cycles, N , for energy harvesting, through an iterative design procedure, the MCRR can achieve the highest PDL under a given set of design constraints. Governing equations in the MCRR operation are derived to identify key specifications and the design guidelines. Using an exemplary set of specs, the optimized MCRR was able to generate 20.9 V DC across a 100 kΩ load from a 1.8 V p , 6.78 MHz sinusoid input in the ISM-band at a Tx/Rx coil separation of 1.3 cm, power transfer efficiency (PTE) of 2.2%, and N = 9 cycles. At the same coil distance and loading, coils optimized for a conventional half-wave rectifier (CHWR) were able to reach only 13.6 V DC from the same source.

Silicon Integrated Optics: Fabrication and Characterization

NASA Astrophysics Data System (ADS)

Shearn, Michael Joseph, II

For decades, the microelectronics industry has sought integration and miniaturization as canonized in Moore's Law, and has continued doubling transistor density about every two years. However, further miniaturization of circuit elements is creating a bandwidth problem as chip interconnect wires shrink as well. A potential solution is the creation of an on-chip optical network with low delays that would be impossible to achieve using metal buses. However, this technology requires integrating optics with silicon microelectronics. The lack of efficient silicon optical sources has stymied efforts of an all-Si optical platform. Instead, the integration of efficient emitter materials, such as III-V semiconductors, with Si photonic structures is a low-cost, CMOS-compatible alternative platform. This thesis focuses on making and measuring on-chip photonic structures suitable for on-chip optical networking. The first part of the thesis assesses processing techniques of silicon and other semiconductor materials. Plasmas for etching and surface modification are described and used to make bonded, hybrid Si/III-V structures. Additionally, a novel masking method using gallium implantation into silicon for pattern definition is characterized. The second part of the thesis focuses on demonstrations of fabricated optical structures. A dense array of silicon devices is measured, consisting of fully-etched grating couplers, low-loss waveguides and ring resonators. Finally, recent progress in the Si/III-V hybrid system is discussed. Supermode control of devices is described, which uses changing Si waveguide width to control modal overlap with the gain material. Hybrid Si/III-V, Fabry-Perot evanescent lasers are demonstrated, utilizing a CMOS-compatible process suitable for integration on in electronics platforms. Future prospects and ultimate limits of Si devices and the hybrid Si/III-V system are also considered.

Purified silicon production system

DOEpatents

Wang, Tihu; Ciszek, Theodore F.

2004-03-30

Method and apparatus for producing purified bulk silicon from highly impure metallurgical-grade silicon source material at atmospheric pressure. Method involves: (1) initially reacting iodine and metallurgical-grade silicon to create silicon tetraiodide and impurity iodide byproducts in a cold-wall reactor chamber; (2) isolating silicon tetraiodide from the impurity iodide byproducts and purifying it by distillation in a distillation chamber; and (3) transferring the purified silicon tetraiodide back to the cold-wall reactor chamber, reacting it with additional iodine and metallurgical-grade silicon to produce silicon diiodide and depositing the silicon diiodide onto a substrate within the cold-wall reactor chamber. The two chambers are at atmospheric pressure and the system is open to allow the introduction of additional source material and to remove and replace finished substrates.