Family of graphene-based superconducting devices

A family of highly sensitive devices based on a graphene nanobridge and superconducting electrodes has been developed, manufactured, and examined. These devices can be used to create a graphene-based integral receiver. A cold-electron bolometer prototype with superconductor-insulator-normal metal tunnel junctions has been studied. Its response to a change in the temperature and external microwave radiation has been measured. A superconducting quantum interferometer with a graphene strip as a weak coupling between superconducting electrodes has been examined. The corresponding modulation of the voltage by a magnetic field at a given current has been measured. The effect of the gate voltage on the resistance of graphene has been analyzed for these samples. To confirm that graphene is single-layer, measurements with the reference samples were performed in high magnetic fields, displaying the half-integer quantum Hall effect.     

Near-field measurement of amplitude and phase in silicon waveguides with liquid cladding

Heterodyne near-field scanning optical microscopy (H-NSOM) has proven useful as a tool for characterization of both amplitude and phase of on-chip photonic devices in air, but it has previously been unable to characterize devices with a dielectric overcladding, which is commonly used in practice for such devices. Here we demonstrate H-NSOM of a silicon waveguide with a liquid cladding emulating the solid dielectric. This technique allows characterization of practical devices with realistic refractive index profiles. Fourier analysis is used to estimate the effective refractive index of the mode from the measured data, showing an index shift of 0.08 from air to water cladding, which is seen to correspond well to simulations.     

CdS-CdSe液晶光阀光电特性分析

对CdS－CdSe液晶光阀的结构及特性进行了分析，对其性能参数进行了测试，此光阀能较好地应用于大屏幕投影显示系统中。     

用分子自组装技术制备的单电子器件的Monte Carlo模拟

用分子自组装技术制备出纳米金单电子器件,并测量了其伏安特性,根据单电子系统的半经典理论,用MonteCarlo法对其结果进行了模拟.结果表明,模拟出的伏安曲线与实测的伏安曲线有较好的一致性,反映了模拟方法用于单电子器件研究的合理性,此外发现,虽然单电子器件两电极间含有众多的纳米粒子,但在低压区,其伏安特性只与少数纳米粒子有关 关键词： 单电子器件 MonteCarlo模拟 分子自组装     

Fiber-optic hydrophone using a cylindrical Helmholtz resonator as a mechanical anti-aliasing filter

Two Michelson interferometric fiber-optic hydrophones that use panda polarization-maintaining fibers and devices have been constructed and tested. The low-frequency acoustic sensitivities of both hydrophones are -159 dB re 1 rad/microPa. One of the hydrophones tested has a small cylindrical Helmholtz resonator that has a break point near 1200 Hz and a measured roll-off of approximately 50 dB/octave, and it is a hydrostatic-pressure-insensitive design. This hydrophone is a prototype device for a class of sensors that can be used to eliminate aliasing in future sonar systems. To our knowledge, this is the first time that such a fiber-optic hydrophone has been reported.     

Low energy selfsputtering yields of nickel

The selfsputtering yield of nickel has been measured by the mass change method for normal incidence in the energy region from 75eV–3.0keV. In this energy region the yield varies from 0.07–3.0atmos/ion. The results are discussed in view of their importance to the plasma-wall interaction in fusion devices.     

Portable in situ fluorescence cytometry of microscale cell-based assays

A portable fluorescence cytometric system has been developed for characterizing chemical concentration and cellular status in microscale cell culture analog (microCCA) devices. Based on discrete optical components, the system provides a modular platform for real-time image measurements applicable to a variety of cell-based microassays. As a feasibility study, we investigated the real-time dynamics of daunorubicin uptake with cultured mouse L-cells in a microCCA compartment. Time course results measured by the portable fluorescence cytometric system confirmed that in the microCCA devices daunorubicin accumulation is proportional to the liquid turnover rate.     

Frequency response of W-band pulsed impatt oscillator operating with a variable load

The frequency response, particularly the chirp characteristics of W-band waveguide mounted IMPATT devices operating with a variable load has been investigated analytically in this work. The measured chirp bandwidth agrees satisfactorily with the computed value based on the proposed device-circuit interaction model.     

Effect of interfacial shallow traps on polaron transport at the surface of organic semiconductors

The photo-induced electron and hole transfer across the semiconductor-dielectric interface in trap-dominated p-type organic field-effect transistors has been investigated. It has been observed that the transfer of electrons into the dielectric results in a decrease of the field-effect mobility of polarons, suggesting that additional shallow traps are generated in the conduction channel. Using this effect, the dependence of the field-effect mobility on the density of shallow traps, mu(N), has been measured, which allowed us to estimate the average polaron trapping time, tau_{tr}=50+/-10 ps, and the density of shallow traps, N0=(3+/-0.5) x 10(11) cm(-2), in the channel of single-crystal tetracene devices.     

Polymer pixel enhancement by laser-induced forward transfer for sensor applications

This paper presents polymer pixel printing for applications in chemoselective sensors where nanosecond laser direct transfer methods, with a triazene polymer (TP) acting as a Dynamic Release Layer (DRL), are used. A systematic study of laser fluence, donor film morphology and both single- and multiple-pixel deposition were optimized with the final goal to obtain continuous pixels of sensitive polymers, polyethylenimine (PEI) and polyisobutylene (PIB), on SAW surfaces. Morphology characterization after the laser transfer has been performed by Optical Microscopy and Scanning Electron Microscopy (SEM). The responses of the coated transducers were measured after deposition with different laser fluences and it was found that a fluence under 625 mJ/cm² was required in order to prevent damage of the interdigital transducers (IDT) of the sensor devices. The sensitivity of the polymer coated devices to acetone concentrations gives an indication that LIFT can be used for printing sensitive polymer pixels onto transducer devices.     

Proprietes optiques,elastiques et elasto-optiques du KRS6

KRS6, a commercially available crystal, was found to be a good material for acousto-optical devices using visible light. It has some high figures of merit and can be found in good optical qualities and large size. The dispersion of the photoelastic coefficients and the refractive index have been measured using fifteen lines of a Kr-Ar laser.     

n型碲镉汞MIS器件动态存储时间研究

通过对动态存储时间的测量，分析了ｘ＝０．３１的ｎ型碲镉汞（Ｈ_1-xＣｄ_xＴｅ）ＭＩＳ器件的少子暗电流机理．理论计算和实验结果都表明，在其工作温度区域（～７７Ｋ），通过禁带中深能级中心辅助的间接隧道电流将限制器件的电学性能。 关键词：     

Electric field modulation of galvanomagnetic properties of mesoscopic graphite

Electric field effect devices based on mesoscopic graphite are fabricated for galvanomagnetic measurements. Strong modulation of magnetoresistance and Hall resistance as a function of the gate voltage is observed as the sample thickness approaches the screening length. Electric field dependent Landau level formation is detected from Shubnikov-de Haas oscillations. The effective mass of electron and hole carriers has been measured from the temperature dependent behavior of these oscillations.     

A novel multiple blade ultrasonic cutting device

In ultrasonic devices consisting of serially coupled tuned components, components whose tuned length dimension is large compared to other dimensions, or components with profiles designed for high gain, the response of the device during operation is often characterised by modal interactions, and especially the excitation of combination resonances. The effects on ultrasonic devices are high noise levels, component failures and poor operating performance. In this paper, energy exchanges between modes are characterised to illustrate the adverse effects of combination resonances. Design solutions are proposed to eliminate these effects which concentrate on reducing the number of modes. In particular, a novel half-wavelength three-blade cutting system tuned to the first longitudinal mode has been designed by finite element modelling. An experimental investigation demonstrates that the measured response does not show evidence of modal interactions.     

Experimental investigation of negative refraction and imaging of 8-fold-symmetry phononic quasicrystals

The focus behaviors of acoustic wave through 8-fold-symmetry phononic quasicrystals have been observed experimentally in this paper. By measuring the field distributions in the image plane, we obtain an elongated image of a point source which has a similar result with phononic crystals. The negative refraction index was measured in two different ways which are very consistent with each other. These properties make the phononic quasicrystals (PQCs) promising for application in a range of phononic devices.     

Ka波段耦合腔行波管放大器设计

由于Ka波段耦合腔行波管放大器设计技术取得了较大的发展,已经可以满足军用雷达的严格要求,这种设计技术也受到更多的关注.这里简要介绍Ka波段耦合腔行波管放大器的设计技术.通过介绍Ka波段耦合腔行波管放大器的基本组成、工作原理及设计中仿真工具的运用来说明这种设计技术.用这种设计技术成功设计出了多种耦合腔行波管放大器,在功率和体积方面突破了原有的Ka波段固态和螺旋线行波管放大器的局限,取得了明显的进步.Ka波段耦合腔行波管放大器的设计技术经过实践验证,在输出功率、带宽及重量方面已经取得了重大突破,满足了现代军用雷达的需求.     

High Sensitive Devices for Radioisotope-Determination in Plant — Soil Materials

The Institute of Experimental Botany of the Czechoslovak Academy of Sciences in Prague has been the methodic centre for isotopic applications to plant — soil material and their utilization for agricultural purposes. The highly sensitive devices were developed partly on the basis of commercial apparatuses, partly they were constructed in the workshop of the Institute. With these devices compounds labelled with ¹¹C, ³⁵S, ³H, ³²P and double labelled compounds have been measured.     

Investigation of waveguide and process parameter of nonlinear optical waveguide in CdS_xSe_(1-x)doped glass

For the first time,it is experiementally verified that the index profile of K~ —Na~ ion-exchanged waveguide in CdS_xSe_(1-x)doped glass follows a second-order polynomial dis-tribution.Mode-dispersion curves have been obtained by computing simplified mode equationin WKB approximation and verified by experiment.Diffusion constant has been measured ac-curately.Technical basis is provided for the design and fabrication of all-optical switching de-vices in this kind of nonlinear waveguide.     

Numerical study of homogeneous dynamo based on experimental von Kármán type flows

A numerical study of the magnetic induction equation has been performed on von Kármán type flows. These flows are generated by two co-axial counter-rotating propellers in cylindrical containers. Such devices are currently used in the von Kármán sodium (VKS) experiment designed to study dynamo action in an unconstrained flow. The mean velocity fields have been measured for different configurations and are introduced in a periodic cylindrical kinematic dynamo code. Depending on the driving configuration, on the poloidal to toroidal flow ratio and on the conductivity of boundaries, some flows are observed to sustain growing magnetic fields for magnetic Reynolds numbers accessible to a sodium experiment. The response of the flow to an external magnetic field has also been studied: The results are in excellent agreement with experimental results in the single propeller case but can differ in the two propellers case.     

Nonvolatile memory devices based on self-assembled nanocrystals

Nonvolatile memory devices are one of the most important components in modern electronic devices. Many efforts have been made to fabricate high-density, low-cost, nonvolatile solid-state memory devices for use in portable/mobile electronic devices such as laptop computers, tablet devices, smart phones, etc. Among the many available nonvolatile memory devices, flash memory devices are of great interest to the electronics industry owing to their simple device structure, enabling high-density memory applications. Flash memory devices in which nanoparticles or nanocrystals are used as the charge-trapping elements have advantages over conventional flash memory devices because the charge-trapping layer and memory performance of the former can be readily optimized. Active research has recently been conducted to fabricate and characterize self-assembled-nanocrystal-based nonvolatile memory devices. We reviewed various strategies for fabricating nanocrystal-based nonvolatile memory devices and discussed the programmable memory properties and the device reliability characteristics of nanocrystal-based memory devices to possibly apply nanocrystal-based memory devices to those used in portable/mobile electronic devices. Finally, novel device applications such as printed/flexible/transparent electronic devices were explored based on nanocrystal-based memory devices.