Low-temperature synthesis of indium tin oxide nanowires as the transparent electrodes for organic light emitting devices

Low-temperature growth of indium tin oxide (ITO) nanowires (NWs) was obtained on catalyst-free amorphous glass substrates at 250?°C by Nd:YAG pulsed-laser deposition. These ITO NWs have branching morphology as grown in Ar ambient. As suggested by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM), our ITO NWs have the tendency to grow vertically outward from the substrate surface, with the (400) plane parallel to the longitudinal axis of the nanowires. These NWs are low in electrical resistivity (1.6×10?? Ω cm) and high in visible transmittance (~90–96%), and were tested as the electrode for organic light emitting devices (OLEDs). An enhanced current density of ~30 mA cm?2 was detected at bias voltages of ~19–21 V with uniform and bright emission. We found that the Hall mobility of these NWs is 2.2–2.7 times higher than that of ITO film, which can be explained by the reduction of Coulomb scattering loss. These results suggested that ITO nanowires are promising for applications in optoelectronic devices including OLED, touch screen displays, and photovoltaic solar cells.     

A parallel-architecture parametric equalizer for air-coupled capacitive ultrasonic transducers

Parametric equalization is rarely applied to ultrasonic transducer systems, for which it could be used on either the transmitter or the receiver to achieve a desired response. An optimized equalizer with both bump and cut capabilities would be advantageous for ultrasonic systems in applications in which variations in the transducer performance or the properties of the propagating medium produce a less-than-desirable signal. Compensation for non-ideal transducer response could be achieved using equalization on a device-by-device basis. Additionally, calibration of ultrasonic systems in the field could be obtained by offline optimization of equalization coefficients. In this work, a parametric equalizer for ultrasonic applications has been developed using multiple bi-quadratic filter elements arranged in a novel parallel arrangement to increase the flexibility of the equalization. The equalizer was implemented on a programmable system-on-chip (PSOC) using a small number of parallel 4th-order infinite impulse response switchedcapacitor band-pass filters. Because of the interdependency of the required coefficients for the switched capacitors, particle swarm optimization (PSO) was used to determine the optimum values. The response of a through-transmission system using air-coupled capacitive ultrasonic transducers was then equalized to idealized Hamming function or brick-wall frequencydomain responses. In each case, there was excellent agreement between the equalized signals and the theoretical model, and the fidelity of the time-domain response was maintained. The bandwidth and center frequency response of the system were significantly improved. It was also shown that the equalizer could be used on either the transmitter or the receiver, and the system could compensate for the effects of transmitterreceiver misalignment.     

Eat Me… Drink Me…

Sean Lally of WEATHERS lets out a rallying cry to all architects. He calls on them to make environmental conditions the subject of design rather than regarding them as a standardised part of a building's services. Here he highlights the potential of material systems, which are usually applied to conditioning the interiors of buildings, in the generation of new forms and activities; whether it is in the honing of the performance aspect of a building's function, as in the Water Cube at Beijing (2008), or in the seasonal planning that underpins the concept behind WEATHERS' Wanderings project (2008-9). Copyright © 2010 John Wiley & Sons, Ltd.     

Precipitation Coating of Monazite on Woven Ceramic Fibers: I. Feasibility

Monazite coatings were deposited on woven cloths and tows of Nextel™ 610 fibers by heterogeneous nucleation and growth using solution precursors. Initial experiments revealed two coating regimes in which monazite was either precipitated both in solution and onto the fiber surfaces or only onto the fiber surfaces depending on the precursor solution concentration and fiber surface area. In both cases, regions of tightly packed fibers within cloth were uncoated. Image analysis of coated fiber cross sections revealed a strong correlation between fiber separation and coating thickness, suggesting that the coating of tightly packed fibers was limited by transport of the reactants in solution to these areas. By adopting a coating procedure in which the tightly packed regions are saturated with reactants before precipitation, more uniform coatings of monazite were obtained throughout the cloth; however, the strength of as-coated and heat-treated fibers was degraded and remains problematic.     

Creep of Nextel™ 610 Fiber at 1100°C in Air and in Steam

Creep of Nextel^?610 fibers was investigated at 1100°C and 100–500 MPa in air and in steam. The effect of loading rate on fiber tensile strength was also explored. The presence of steam accelerated creep and reduced fiber lifetimes. Loading rate had a considerable effect on tensile strength in steam, but not in air. A linear elastic crack growth model was used to predict the creep lifetimes from the constant loading rate data. The dependence of tensile strength on loading rate and the predictability of creep lifetimes suggest that the failure mechanism in steam was environmentally assisted subcritical crack growth. The creep‐rupture data were analyzed in terms of a Monkman‐Grant (MG) relationship. Monkman‐Grant parameters for creep‐rupture data were the same in steam and air, and predicted creep‐rupture at 1100°C in both environments. A grain‐size increase of about 25% was observed by TEM after 100 h at 1100°C in steam, which was about two times that observed in air.     

Transformation Plasticity in (GdxDy1−x)PO4 Fiber Coatings During Fiber Push Out

The reduction in fiber push‐out stress by transformation plasticity in xenotime rare‐earth orthophosphate fiber–matrix interphases was demonstrated. Processing methods for transformable xenotime coatings were explored. For conversion to xenotime during processing, (Gd_xDy_1?x)PO₄ solid solutions had to be more Dy‐rich than those for pellets. Single‐crystal alumina fibers were coated with 10–20 μm of (Gd_0.4Dy_0.6)PO₄ xenotime and incorporated into polycrystalline alumina matrices. Coated fiber push‐out stresses were between 10 and 80 MPa, significantly lower than those for fibers with other rare‐earth orthophosphates coatings. Phase transformations and deformation mechanisms were characterized by SEM and TEM in fiber coatings after push out. Bands of deformed coating several micrometers in width formed during fiber push out. Cataclastic flow with fracture, granulation, translation, rotation, and intense plastic deformation of coating grains was observed. Three phase transformations may occur in heavily deformed particles in the deformation band: xenotime → monazite, xenotime → anhydrite, and anhydrite → monazite. Anhydrite was abundant as a fine lamellar phase on (100) planes in xenotime. Selected area electron diffraction and high‐resolution TEM confirmed formation of monazite in a variety of heavily deformed particles. Issues for use of rare‐earth orthophosphate transformation plasticity to lower fiber pull‐out stress in ceramic matrix composites are discussed.     

跨组织安全物品追溯

由于供应链的应用场景往往需要多个公司的协同,物品追溯服务也就涉及跨组织的场景,因此有必要研究跨组织安全物品追溯的理论和方法。本文提出一个跨组织物品追溯的形式化模型和跨组织物品追溯服务的三个安全属性：可追溯性、可信性和隐私保护;设计一个跨组织安全物品追溯框架,及其中的三个基本协议：发货协议、验证协议和收货协议;本文最后介绍一个满足上述三种安全属性的跨组织安全物品追溯原型系统,并对其进行评估。     

Reactive ballistic deposition of nanostructured model materials for electrochemical energy conversion and storage

Porous, high surface area materials have critical roles in applications including catalysis, photochemistry, and energy storage. In these fields, researchers have demonstrated that the nanometer-scale structure modifies mechanical, optical, and electrical properties of the material, greatly influencing its behavior and performance. Such complex chemical systems can involve several distinct processes occurring in series or parallel. Understanding the influence of size and structure on the properties of these materials requires techniques for producing clean, simple model systems. In the fields of photoelectrochemistry and lithium storage, for example, researchers need to evaluate the effects of changing the electrode structure of a single material or producing electrodes of many different candidate materials while maintaining a distinctly favorable morphology. In this Account, we introduce our studies of the formation and characterization of high surface area, porous thin films synthesized by a process called reactive ballistic deposition (RBD). RBD is a simple method that provides control of the morphology, porosity, and surface area of thin films by manipulating the angle at which a metal-vapor flux impinges on the substrate during deposition. This approach is largely independent of the identity of the deposited material and relies upon limited surface diffusion during synthesis, which enables the formation of kinetically trapped structures. Here, we review our results for the deposition of films from a number of semiconductive materials that are important for applications such as photoelectrochemical water oxidation and lithium ion storage. The use of RBD has enabled us to systematically control individual aspects of both the structure and composition of thin film electrodes in order to probe the effects of each on the performance of the material. We have evaluated the performance of several materials for potential use in these applications and have identified processes that limit their performance. Use of model systems, such as these, for fundamental studies or materials screening processes likely will prove useful in developing new high-performance electrodes.     

软件可配置的模拟I/O助力更紧凑更方便的校准器设计

工业模拟I/O(input/output,输入输出)模块用于和工厂内的传感器、执行器之间实现精准、低电平的电压信号与电流信号的收发.同所有电子器件一样,长时间的重复使用和不断变化的环境条件会导致其性能下降,因此需要对其进行定期校准以确保其能够按照既定标准持续运行.