Porous carbonized egg white as efficient electrocatalyst for oxygen reduction reaction

Hierarchical porous carbonized egg white (EW) is synthesized and used as oxygen reduction reaction (ORR) catalyst. The typical EW that is carbonized at 650 °C (EW-650) possesses ultrahigh specific surface area of 1904 m² g^?1, large average pore diameter of 9.8 nm, high contents of doped heteroatoms (N, O and S), fairly high graphitization degree and dense defects, corresponding to dense active sites and excellent transportation of both mass and electrons. Therefore, the EW-650 shows higher activity than commercial Pt/C for ORR in both alkaline and acidic media even at higher mass loadings, with excellent cyclic stability. The effects of reaction temperature and electrolyte concentration on ORR activity are also studied. It is found that appropriate temperature and electrolyte concentration speed up ORR kinetics, ensure higher oxygen solubility and favor mass transportation.     

基于改进CORDIC算法的DDS设计

针对基本CORDIC算法的DDS计算速度随迭代次数增加而降低的问题,对CORDIC算法提出了一些改进.采用了角度分解预测旋转方向和多级迭代并行计算的方法,代替传统算法的多重迭代.时序仿真结果表明:改进的算法实现相位幅度转换;与基本CORDIC算法相比,在保持数据较高精度的同时提高了运算速度.此种设计具有运算速度快、计算...     

油气井用合成树脂胶凝材料研究综述

合成树脂作为一种完全不同于常规水泥的新型胶凝材料,体现出其独特的优势,成为近些年研究的热点。通过对合成树脂的种类及其优缺点、固化机理进行总结分析,提出了作为油气井胶凝材料的合成树脂的性能要求,并对国内外合成树脂胶凝材料的最新研究进行了全面综述。另外,针对油气井合成树脂胶凝材料的研究现状,探讨了其发展趋势。      

改进的人工势能场在足球机器人避障中的应用

本文通过分析传统人工势场法的不足,提出一种新的人工势场法.通过引入逃脱力,并且采用EAPF结合遗传算法来获得优化的势能场函数,解决足球机器人导航和避障问题,仿真结果表明能达到时间最优的目的.     

Synthesis of CeO2 nanoparticles with different morphologies and their properties as peroxidase mimic

The overall objective of this work was to identify and determine the controlling factors of catalytic activity of CeO₂ nanoparticles with different properties. Therefore, four kinds of CeO₂ nanoparticles are successfully synthesized and used as peroxidase mimics. The results reveal that the catalytic activity is related to specific surface area and surface oxygen (O_sur) content. For different CeO₂ nanoparticles, specific surface area is the leading factor of catalytic activity. The catalytic activity increases with the increasing specific surface area. If the CeO₂ nanoparticles have similar specific surface area, the less O_sur contains, the lower catalytic activity will be. Meanwhile, crystallinity is not the influence factor of catalytic activity. Bamboo-like CeO₂ (B-CeO₂) nanoparticles show excellent catalytic activity and the reaction conditions are optimized. Furthermore, the catalytic activity of B-CeO₂ nanoparticles decreases very slightly after 15 cycles of the catalysis experiment. Therefore, B-CeO₂ nanoparticles can serve as effective recyclable peroxidase mimics.     

苎麻织物一浴一步法前处理工艺探讨

本文介绍了催化稳定剂R—1用于苎麻等织物退煮漂一浴一步法温和前处理的工艺处方和工艺条件,并与常规工艺进行了对比。实验表明,所研制的温和前处理助剂R—1可用于苎麻等织物的退煮漂一浴一步法前处理工艺,其较佳的工艺条件为催化稳定剂R—18g/L、100％H_2O_24g/L、pH值8.0、温度95℃以上或沸腾、处理时间2h。处理后织物白度值可以达到或超过常规三步法处理织物,而毛效基本相同;强力大大高于常规三步法,手感也比常规柔软。     

煤基甲醇制清洁柴油添加剂聚氧醚的研究

开发了以固体酸性材料分子筛或固体超强酸为催化剂,由甲醇与三聚甲醛或多聚甲醛为原料合成聚氧醚的工艺。通过对催化剂种类、酸性、比表面、原料配比、反应分压考察发现,以固体超强酸Z5为催化剂、403 K、自生压力、醇醛摩尔比2.2时,能够获得最高的原料转化率和聚氧醚产物收率。研究表明,所用固体超强酸较小的比表面积使得催化剂上的酸性位较少,限制了催化剂的活性。     

香叶基砜的合成方法研究

香叶醇是合成萜类化合物的重要原料.通常是将其制成砜或硫醚后,利用α-氢的活泼性,在强碱作用下形成α-碳负离子,然后与亲电试剂进行取代反应,形成新的碳链,由此合成二萜和其他长链多萜.香叶基砜作为最初的中间产物,能大量且高纯度地合成可以大大节省工作.     

H13模具钢铝合金工件生产应用现状综述

介绍了H13钢模具在铝合金工件生产上损坏的原因,H13中碳化物的尺寸、分布以及形貌对寿命的影响和合金化元素对模具性能的影响。综述了H13各种热处理工艺以及表面处理的方法及其对H13模具使用寿命的影响,以期促进这些工艺的应用和发展。     

基于光流场和Grabcut算法融合的运动目标分割

文章提出一种光流场和Grabcut算法融合的运动目标分割方法,利用光流场计算相邻两帧图像得到运动目标初步检测的模糊结果,将结果处理后作为Grabcut前景标定依据,取代Grabcut人工交互过程,得到最终运动目标精确检测结果.