具有准单级聚焦特性的梯形波带片（英）

为改进用于X射线聚焦的二值化Gabor波带片目前所存在的结构复杂、不利于加工制作的问题,在不改变梯形透过率函数的前提下,通过将传统的梯形孔基元变为平行四边形基元应用于波带片的设计之中,提出了一种聚焦效率更高的具有准单级聚焦特性的波带片。理论推导显示,该波带片除了像Fresnel波带片一样能够消除偶数级的焦点外,还可以消除3q级（q为整数）的焦点,1/m4（m为焦点级数）的效率衰减系数也使得高级衍射得到了很好的抑制。MATLAB数值模拟的结果证明,该波带片的特性不仅满足以上推论,还具有比Fresnel波带片和环带扇形基元阵列波带片更低的背景噪声,可以看作是一种准单级聚焦的新型波带片。此外,在同一波带内,这种基于平行四边形基元孔的波带片设计的透光区始终保持各处的径向宽度为该波带的一半,且扇区结构简单一致,能够降低不少加工难度,易于推广应用。     

“闪光二号”5 T脉冲强磁场装置

为了满足闪光二号加速器材料热力学效应研究的新需求,设计了一套电容器储能型脉冲强磁场装置。装置主要由储能电容器、半导体放电开关、磁场线圈及高压恒流充电源组成。磁场线圈中心处最大磁感应强度可达5 T,并且可以通过调整磁场线圈与二极管的相对位置实现磁透镜比的调节。通过理论计算和数值模拟相结合的方法对脉冲强磁场的关键参数进行了分析,然后进行了脉冲强磁场的工程设计,最后使用该强磁场装置进行了实验研究。强磁场实验中,当储能电容器充电21 kV时,在磁场线圈中心处获得了5.3 T脉冲强磁场。     

基于多尺度分解的超光谱图像异常检测

提出了一种基于多尺度分解的超光谱图像异常检测算法。在目标和背景均未知的前提下,利用光谱和空间两种信息完成对异常目标信号的定位,从而实现超光谱遥感数据中异常目标检测。首先利用非下采样塔式变换对超光谱图像进行分解,将其划分为不同尺度子块;然后依据超光谱图像同一波段不同尺度空间内相邻系数的相关性,采用不同波段各个尺度空间的反锐化掩模方法优化背景数据分布,从而抑制异常数据对背景的干扰;最后利用设计的核RX算子得到异常目标检测结果。为验证方法的有效性,利用真实和模拟的AVIRIS数据进行了实验,并与经典RX算法相比较,实验结果表明,基于非下采样塔式分解的异常检测方法具有更好的检测性能和较低的虚警。     

3 MV多级多通道缩比开关自击穿特性

通过短接电极间隙,开展了3 MV多级多通道缩比开关不同间隙级数和单独触发间隙的自击穿特性分析,结果表明：自击穿电压随电极间隙距离不是线性增加,与Bradley经验公式存在差距。采用Ansoft软件模拟了实验开关不同级数的电场分布,得到不同级数开关电场分布的不均匀系数。结合缩比开关自击穿实验数据、Bradley经验公式和电场分布不均匀系数,在Bradley经验公式中加入开关作用时间因素和电场不均匀系数,得到一个Bradley外推公式,能较好地反应多级多通道气体开关的自击穿电压,使3 MV实际开关自击穿电压理论值与实验值误差减小到5%。     

Diluting the Resistance of Built-in Electric Fields in Oxygen Vacancy-enriched Ru/NiMoO4-x for Enhanced Hydrogen Spillover in Alkaline Seawater Splitting

Recently, hydrogen spillover based binary (HSBB) catalysts have received widespread attention due to the sufficiently utilized reaction sites. However, the specific regulation mechanism of spillover intensity is still unclear. Herein, we have fabricated oxygen vacancies enriched Ru/NiMoO_4-x to investigate the internal relationship between electron supply and mechanism of hydrogen spillover enhancement. The DFT calculations cooperate with in situ Raman spectrum to uncover that the H* spillover from NiMoO_4-x to Ru. Meanwhile, oxygen vacancies weakened the electron supply from Ru to NiMoO_4-x, which contributes to dilute the resistance of built-in electric field (BEF) for hydrogen spillover. In addition, the higher ion concentration in electrolyte will promote the H* adsorption step obviously, which is demonstrated by in situ EIS tests. As a result, the Ru/NiMoO_4-x exhibits a low overpotential of 206 mV at 3.0 A cm⁻², a small Tafel slope of 28.8 mV dec⁻¹, and an excellent durability of 550 h at the current density of 0.5 A cm⁻² for HER in 1.0 M KOH seawater.     

石墨型高能两电极气体开关

为大型激光装置能源模块研制了一种采用石墨电极的两电极气体开关,阐述了石墨应用于高能两电极气体开关的技术关键,对气体开关中气体间隙的最优结构进行了电场强度分析。参考美国国家点火装置(NIF)能源模块中ST-300气体开关的已知参数,对研制成功的石墨型两电极开关进行了电气特性试验,证明了石墨型气体开关能够实现峰值电流达300 kA以上,单次转移电荷量100 C以上,寿命超过1 000次,满足1.2 MJ大型激光装置能源模块的工程技术要求。     

上海软X射线自由电子激光装置直线加速器束流位置测量系统研制

上海软X射线自由电子激光装置（SXFEL）作为中国第一台工作在软X射线波段的第四代光源,其产生的激光具备短波长、全相干、超高亮度、超短脉冲长度等优点,预期将会在基础科学研究领域中发挥出重要的作用。基于直线加速器的特点和需求,在SXFEL的注入器与直线加速段上选择了条带型束流位置测量系统（SBPM）作为束团位置测量工具。该系统由SXFEL束测团队自主研发设计,由条带探头、前端信号调理电子学与专用数字信号束流位置处理器（DBPM）组成,系统设计上借鉴上海同步辐射光源（SSRF）的同类型设备,并根据SXFEL的特点做了进一步的优化,束流实验结果表明该系统位置测量系统分辨率好于5.7 μm@188 pC,达到国际先进水平,满足了SXFEL注入器和直线加速器段对束流位置测量分辨率的设计要求。     

Intermetallic Compounds: Liquid-Phase Synthesis and Electrocatalytic Applications

Characterized by long-range atomic ordering, well-defined stoichiometry, and controlled crystal structure, intermetallics have attracted increasing attention in the area of chemical synthesis and catalytic applications. Liquid-phase synthesis of intermetallics has arisen as the promising methodology due to its precise control over size, shape, and resistance toward sintering compared with the traditional metallurgy. This short review tends to provide perspectives on the liquid-phase synthesis of intermetallics in terms of both thermodynamics and methodology, as well as its applications in various catalytic reactions. Specifically, basic thermodynamics and kinetics in the synthesis of intermetallics will be first discussed, followed by discussing the main factors that will affect the formation of intermetallics during synthesis. The application of intermetallics in electrocatalysis will be demonstrated case by case at last. We conclude the review with perspectives on the future developments with respect to both synthesis and catalytic applications.     

Fabrication of ZnSe/C Hollow Polyhedrons for Lithium Storage

ZnSe has got extensive attention for high-performance LIBs anode due to its remarkable theoretical capacity and environmental friendliness. Nevertheless, the large volume variation for the ZnSe in the discharge/charge processes brings about rapid capacity fading and poor rate performance. Herein, ZnSe/C hollow polyhedrons are successfully synthesized by selenization of zeolitic imidazolate framework-8 (ZIF-8) with resorcinol-formaldehyde (RF) coating. The protection of C layer derived from RF coating layer and Ostwald ripening during the process of selenization play important roles in promoting formation of ZnSe/C hollow polyhedrons. The ZnSe/C hollow polyhedrons exhibit good rate performance and long-term cycle stability (345 mAh g⁻¹ up to 1000 cycles at 1 A g⁻¹) for lithium ion batteries (LIBs) anode. The improved electrochemical performance is benefit from the unique ZnSe/C hollow structure, in which the hollow structure can effectively avoid terrible volume expansion, and the thin ZnSe/C shell can not only provide adequate diffusion paths of lithium ions and but also enhance the electronic conductivity.     

Peroxidase-Like Platinum Clusters Synthesized by Ganoderma lucidum Polysaccharide for Sensitively Colorimetric Detection of Dopamine

The sensitive and selective detection of dopamine (DA) is very important for the early diagnosis of DA-related diseases. In this study, we reported the colorimetric detection of DA using Ganoderma lucidum polysaccharide (GLP) stabilized platinum nanoclusters (Pt_n-GLP NCs). When Pt₆₀₀-GLP NCs was added, 3,3’,5,5’-tetramethylbenzidine (TMB) was rapidly catalyzed and oxidized to blue oxTMB, indicating the peroxidase-like activity of Pt₆₀₀-GLP NCs. The catalytic reaction on the substrate TMB followed the Michaelis-Menton kinetics with the ping-pong mechanism. The mechanism of the colorimetric reaction was mainly due to the formation of hydroxyl radical (•OH). Furthermore, the catalytic reaction of Pt₆₀₀-GLP NCs was used in the colorimetric detection of DA. The linear range for DA was 1–100 μM and the detection limit was 0.66 μM. The sensitive detection of DA using Pt-GLP NCs with peroxidase-like activity offers a simple and practical method that may have great potential applications in the biotechnology field.