Micro-X: Mission Overview and Science Goals

Micro-X, the High-Resolution Microcalorimeter X-ray Imaging Rocket, is a sounding rocket space telescope that will combine a transition-edge-sensor (TES) X-ray microcalorimeter array with a conical imaging mirror to obtain high spectral resolution images of extended and point X-ray sources. Microcalorimeters measure the energy of an absorbed photon by sensing the increase in temperature of the sensor from the thermalization of the absorbed photon’s energy. The advantages and scientific promise of this technology have fueled active development for the past 20 years. We will leverage this development and take the next step by producing a flight-qualified system that will serve as a pathfinder for future missions. Our scientific program will initially focus on extended sources, for which our high-spectral-resolution observations have distinct advantages over other technologies. For our initial flight, we will observe the bright eastern knot in the Puppis A remnant, a site of complex cloud-shock interactions and ejecta enrichment. A Micro-X observation of the bright eastern knot of Puppis A will obtain a line-dominated spectrum with 90,000 counts collected in 300 seconds at 2 eV resolution across the 0.3–2.5 keV band.      

The Noise and Energy Resolution of the Ti/Au Bilayer X-ray TES Calorimeter with an Au Absorber

We fabricated the TES microcalorimeter with TES(Ti/Au) and gold absorber, and obtained FWHM energy resolution of 4.8±0.3 eV at 5.9 keV. The baseline resolution, i.e. the resolution determined by noise, was 4.1±0.1 eV. From the noise spectra we found that the square of the baseline resolution could be approximately decomposed into contributions of three noise components. They are estimated to be (2.5 eV)² (the intrinsic noise), (1.5 eV)² (the readout noise), and (3.0 eV)² (so-called excess noise). There is additional broadening of (2.5 eV)² from the baseline resolution. The excess noise is the largest limiting factor of the energy resolution of the device.      

稀土热扩渗在注塑模具中的运用

在＂以塑代钢＂、＂以塑代木＂的必要趋势下,注塑模具的发展就更显得重要,尤其是最能代表生产力的长寿命、高精度的模具。文中简要介绍了稀土热扩渗技术在注塑模具表面处理中的运用,并将其与未添加稀土渗剂的传统热扩渗技术相比较,全面有效的说明了稀土热扩渗的优势,有效催渗,并能增加渗层厚度与硬度,提高注塑模具的使用寿命与精度。     

超材料吸波器的极化特性研究进展

超材料由于具有吸波特性而引起了人们的极大兴趣.简要介绍了超材料产生吸波的原理,并着重阐述了吸波超材料在微波段、光波段以及太赫兹波段的极化特性和相应超材料吸波器结构的模拟及实验研究进展.这种超材料的吸波特性在军事和民用上具有潜在的应用价值.     

Diffusion of cobalt in ion-implanted ZnO

Diffusion of implanted ⁵⁷Co in ZnO has been determined in the temperature range 660-950 °C using the modified radiotracer technique. The diffusion was found to follow the Arrhenius type relation with an activation enthalpy of (2.9 ± 0.3) eV and a pre-exponential factor of 3 × 10^− 4 m²/s. Supported by diffusion data and conclusions provided in the literature, it is proposed that cobalt diffuses substitutionally in ZnO.     

钛－镍－不锈钢接头中元素的扩散及其对性能的影响

采用纯镍作中间过渡金属，对钛合金ＴＣ４与不锈钢１Ｃｒ１８Ｎｉ９Ｔｉ扩散焊接头的结合性能进行了试验研究，利用电子探针测定了扩散层中元素的分布。结果表明，采用镍作中间过渡金属，可以获得钛合金与不锈钢的牢固连接，但在镍与钛之间还是形成了金属间化合物薄层，对接头的性能有较大的影响。     

Mesoscopic Simulation of Diffusion Characteristics in the Corrosion Film

A cellular automata model was used to study the diffusion characteristics in the corrosion film at a mesoscopic scale. The model focused on a metal/film/electrolyte system, including a series of local evolution rules. The effect of diffusion rate on the film growth and metal corrosion was investigated. The result showed that the growth rate of the film followed a power law with the diffusion steps, and the corrosion rate had the same law as that of the film growth in the model with the feedback effect. There existed a diffusing plane in the film, where the concentration of the diffusing species did not depend on time. The diffusion steps were found to have a great influence on the position and species concentration of the diffusing plane.     

Diffusion length of photoexcited carriers in GaN

When additional carriers are introduced in a material with a non uniform concentration, they tend to diffuse on a scale given by their diffusion length. This parameter can be measured by different methods. Depending on the conditions, different values can be found as the recombination mechanisms differ. In this paper, we present the situation in GaN with various experiments including the photocarrier grating method, photoluminescence and the spectral response in photoconductors. We show that the diffusion length varies from 0.1 μm to a few μm depending on experimental conditions. The interpretation is given based on the diffusion equations and on the analysis of the recombinations.     

Neutron Reflectometry: A Tool to Investigate Diffusion Processes in Solids on the Nanometer Scale

The investigation of self‐diffusion for the characterization of kinetic process in solids is one of the most fundamental tasks in materials science. We present the method of neutron reflectometry (NR), which allows the detection of extremely short diffusion lengths in the order of 1 nm and below at corresponding low self‐diffusivities between 10^?25 and 10^?20 m² s^?1. Such a combination of values cannot be achieved by conventional methods of diffusivity determination, like the radiotracer method, secondary ion mass spectrometry, quasielastic neutron scattering, or nuclear magnetic resonance. Using our method, the extensive characterization of materials which are in a non‐equilibrium state, like amorphous or nanocrystalline solids becomes possible. Due to the small experimentally accessible diffusion length microstructural changes (grain growth and crystallization) taking place simultaneously during the actual diffusion experiment can be avoided. For diffusion experiments with NR isotope multilayers are necessary, which are chemical homogeneous but isotope modulated films. We illustrate the basic aspects and potential of this technique using model systems of different classes of materials: single crystalline germanium, amorphous silicon nitride, and nanocrystalline iron.     

L~p-Inversion of the Diffusion Equation(Dedicated to Professor You Zhaoyong for his 60th brithday)

The ranges of the propagation operator for the diffusion equation are characterized. Thus, the formal inversion formula for the diffusion equation is made precise in Lp space setting.     

A New Model of Interfacial Physical Contact in Diffusion Bonding

Through eliminating voids not affecting the primary bonding process, and incorporating interlayer and flexible base material, the interface geometry character and brief mathematics process were put forth. Through analyzing contact process of diffusion bonding, contact area model was settled. It can interpret the phenomenon of different interface areas taking on different strengths. In the course of physical contact, shear stresses serve an important function for the plastic deformation and the cohesion of interface voids.     

平板式SOFC结构热应力的有限元分析

采用有限元数值计算方法, 对平板式固体氧化物燃料电池(SOFC)的结构建立了三维有限元分析模型, 模拟计算了平板式SOFC单电池在均匀温度场中由于各层部件之间的热膨胀系数差异而产生的热应力, 并对模拟结果进行了分析和讨论, 为优化平板式SOFC的材料选择和结构设计提供了依据. 计算结果表明: 在阳极(或阴极)与电解质界面处出现热应力的最大值; 界面热应力的大小及分布与电极材料的热膨胀系数和温度载荷密切相关.     

Diffusion in FSW Joints by Inserting the Metallic Foils

The aims of this investigation were to study diffusion phenomenon in friction stir welding （FSW） joints and its influence on the tensile strength of joints. To study diffusion in stir zone, various metallic foils were inserted between two pure aluminium plates. The thin foils of pure copper, pure zinc, brass and Cu-Zn-Ni alloy with the thickness of 250 μm were used as metallic foils. The transversal cross sections of welds were observed by optical microscopy and scanning electron microscopy （SEM） equipped with an energy dispersive X-ray spectroscopy （EDS） system. The spot analyses near the metallic foils indicated that diffusion occurs from foils into the aluminium plates during welding; consequently, the strength of stir zone increases even by 50%. Besides, the metallic foils could reveal the flow of metal after FSW process.     

Diffusion behavior of aluminum in the surface layer of iron processed by shot peening

An ultrafine-grained surface layer was fabricated on a pure Fe plate by the shot peening process. The average grain size within the surface layer of 10 μm thick is about 28 nm. The diffusion kinetics of Al was measured by secondary ion mass spectrometry within a temperature range of 300-380 °C. The diffusion coefficient of Al in the nanocrystalline layer is about 4 orders of magnitude higher than that in coarse-grained Fe. The activation energy of Al diffusion in nanocrystalline layer is 1.38 eV, which is much smaller than that reported for Al diffusion in the conventional Fe. The enhanced diffusivity of Al may originate from a considerable amount of nonequilibrium grain boundaries and a high density of dislocations in the surface layer processed by shot peening.     

Diffusion barrier performance of nano-structured and amorphous Ru-Ge diffusion barriers for copper metallization

In the experiment, nano-structured and amorphous ultrathin Ru-Ge interlayers (∼15 nm in thickness) were deposited between Cu(Ru) alloy film and Si substrate via co-sputtering functioning as preventive diffusion barrier layers. After annealing at different temperatures, X-ray diffraction and four-point probe method revealed that the amorphous Ru-Ge layer effectively suppressed the Cu diffusion into Si substrate up to a temperature of at least 873 K; however, it is less than 773 K for the nano-structured Ru-Ge layer. A self-formed amorphous multilayer of Ru(RuO_x)/RuGe_xCu_y could be attained by annealing Cu/Cu(Ru)/Ru-Ge(amorphous)/Si system at a very low temperature (even 473 K). The results proved that the amorphous Ru-Ge system could self-form the multilayer diffusion barrier before the diffusion reaction between Cu and Si and improved the thermal stability of the Cu interconnection significantly.     

Use of Fractional Factorial Designs in Antiviral Drug Studies

Experimental design and analysis is an effective and commonly used tool in scientific investigations and industrial applications. Many successful applications have been reported in engineering domains, such as chemical engineering, electrical engineering, and mechanical engineering. However, few cases have been reported in biological research, particularly in virology study. Antiviral drug combinations are increasingly used to reduce possible drug‐resistant viral mutant and reduce cytotoxicity. Drug combinations have often been reported to have higher efficacy and lower individual drug dosage. However, the combined antiviral drug effect is generally hard to assess. One important reason is due to the complex interactions between biological systems and drug molecules. We report a study using fractional factorial designs to investigate a biological system with Herpes simplex virus type 1 and five antiviral drugs. The experiment uses a novel composite design that consists of a 16‐run fractional factorial design and an 18‐run orthogonal array. The results indicate that two chemical drugs, Ribavirin and Acyclovir, are more effective than three Interferon drugs. Furthermore, significant interactions exist within the Interferon drug group and within the Ribavirin‐Acyclovir chemical drug group, but the interactions between the Interferon group and the chemical group are not significant. These observations have major implications in the understanding of antiviral drug mechanism towards better design of combinatorial antiviral drug therapy. Copyright © 2012 John Wiley & Sons, Ltd.