One‐Pot Synthesis of Framework Porphyrin Materials and Their Applications in Bifunctional Oxygen Electrocatalysis

Organic framework materials constructed by covalently linking organic building blocks into framework structures are highly regarded as paragons to precisely control the material structure at the atomic level. Herein, a direct synthesis methodology is proposed as a guidance for the bulk synthesis of organic framework materials. Framework porphyrin (POF) materials are one‐pot synthesized to demonstrate the advances of the direct synthesis methodology. The as‐synthesized POF materials are intrinsically 2D and exhibit impressive versatility in composition, structure, morphology, and function, delivering a free‐standing POF film, hybrids of POF and nanocarbon, and cobalt‐coordinated POF. When applied as electrocatalysts for oxygen reduction reaction and oxygen evolution reaction, the cobalt‐coordinated POF exhibits excellent bifunctional electrocatalytic performances comparable with noble‐metal‐based electrocatalysts. The direct synthesis methodology and resultant POF materials demonstrate the ability of controlling materials at the atomic level for energy electrocatalysis.     

二氧化钒的相变调控特性及可重构超表面天线应用研究

对二氧化钒(VO₂)薄膜的相变调控特性及方法进行了理论分析和实验探索。采用电激励方式研究了不同电极对相变程度的影响,发现电极尺寸和形状与绝缘状态下电阻的变化密切相关,从而影响相变程度。此外,相变程度也受不同调控方式的影响,可以用焦耳热原理解释。进一步将VO₂薄膜与超表面结构相结合,设计实现了大范围频率可重构的超表面天线。相比传统开关,VO₂薄膜在毫米波频段具有隔离度高、损耗低的优势,可为进一步研制高性能可调器件和天线提供重要的技术指导。     

LD泵浦Nd:YVO_4/Cr:YAG激光器的被动调Q锁模

报道了实验中发现的可饱和吸收被动调Q晶体Cr:YAG的调Q锁模现象,在插入不同透过率的Cr:YAG片以及注入不同的泵浦电流时,得到了不同的调Q锁模输出波形,并对这一现象作了初步的讨论,总结出一些规律。     

电子组装中助焊剂的选择 (续一)

助焊剂是电子组装技术中最重要的材料之一,其通过去除材料表面氧化膜及污染物等,保证钎料和母材之间很好的润湿,形成良好焊点。介绍了助焊剂的作用与组成、分类与性能要求以及涂覆方式和工艺评定,有助于实际生产中助焊剂的选择与使用。     

抛光片IPA干燥技术研究

以Marangoni效应为基础的IPA干燥技术在衬底抛光片的干燥中遇到了瓶颈,即干燥后出现水痕缺陷。Marangoni干燥过程中,抛光片表面的水符合重力场下的杨方程模型,其脱离效果与晶片提拉速率和IPA流量密切相关。研究中发现,IPA流量在20L／min、提拉速率在lmm／s时干燥效果最佳;另外,Marangoni干燥过程不能完全去除晶片底部的残水．需要营造合适的蒸发环境,减压排风下供给适量的IPA蒸汽有助于底部残水的去除。晶片与花篮在干燥过程中有相互影响,完全分离的模式可以消除这种影响,但同时会使干燥时间增长。     

斜侵彻时攻角对弹道影响的数值研究

为弄清斜侵彻时攻角对弹道的影响,应用LS-DYNA有限元仿真软件对弹体正、斜侵彻混凝土靶板过程进行了三维数值模拟,通过比较正侵彻时仿真结果与Young经验公式计算结果,验证了有限元模型的合理性,而后通过改变弹体侵彻角度和弹速方向,研究了斜侵彻条件下攻角对弹道形状、侵彻深度及爆炸效果的影响。结果表明:斜入射时正、负攻角对应弹道形状差别较大;绝对值相等的情况下,正攻角的侵彻深度及爆炸效果均优于负攻角。     

基于ARM的高速数据采集卡

提出一种基于LPC2142的具有USB(通用串行总线)接口的高速数据采集卡的设计方案,对基于ARM7处理器LPC2142和FPGA器件的软硬件设计作了介绍.该设计方案解决了高速实时信号与接口总线之间的速度兼容问题,即插即用,具有较高的实用价值.     

Novel 5:1 Unequal Wilkinson Power Divider Using Offset Double-Sided Parallel-Strip Lines

A novel 5:1 unequal Wilkinson power divider using the offset double-sided parallel-strip lines (DSPSL) is proposed. High characteristic impedance is realized by offsetting the top and bottom strips of the DSPSL, which cannot be achieved using other conventional transmission lines such as microstrip line due to its fabrication limitation. The quarter guided wavelength of the offset DSPSL has been analyzed for the proposed power divider design. The simulated and measured results are presented to verify our proposed idea