基于时间分辨荧光光谱法同时测定己酸乙酯与乙酸乙酯

提出了一种基于时间分辨荧光光谱分析法同时测定己酸乙酯和乙酸乙酯混合液中各组分浓度的方法。实验测得两种单体物质的荧光发射光谱重叠度达到78%。对于荧光发射光谱重叠度很高的物质使用普通荧光方法结合算法也很难进行定量分析。而通过量子化学计算结果,对两种单体的分子结构分析,得到己酸乙酯的荧光寿命长于乙酸乙酯。通过时间分辨荧光光谱测量得到己酸乙酯和乙酸乙酯的荧光寿命分别为1.0和5.3 ns。两种物质的荧光发射光谱重叠严重,但是其荧光衰减曲线有明显的差别,所以提出使用时间分辨荧光光谱法对两种物质进行定量分析。通过分析两种物质不同体积比下的荧光衰减曲线的变化趋势,建立两种物质体积比的预测模型,并对其进行检验。实验结果表明：该方法能够实现混合溶液中各组分体积比的测量,其测量的平均残差控制在1%以内,具有一定的实用价值。     

同轴静电纺丝法制备TiN@MnO纤维及其电化学性能研究

本文以钛酸四丁酯和乙酰丙酮锰为起始原料,聚乙烯吡咯烷酮(PVP)为分散剂分别配制高分子溶液. 采用同轴静电纺丝法制备了TiN@MnO前驱体,并经氨气处理得到了具有芯-壳结构的TiN@MnO同轴纤维. 采用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、X射线能量色散谱(EDX)和物理吸附仪分析、观察和表征TiN@MnO同轴结构纤维,其比表面积达16 m2?g-1. 循环伏安曲线测试(CV)表明,在20 mV?s-1倍率下,TiN@MnO同轴纤维电极比电容保持率为2 mV?s-1倍率下的81%,充分说明TiN和MnO两种组分的协同效应提高了电极的倍率性能.     

Numerical studies on evolution of secondary streamwise vortices in transitional boundary layers

Formation and evolution of secondary streamwise vortices in the compressible transitional boundary layers over a flat plate are studied using a direct numerical simulation method with high-order accuracy and highly effective non-reflecting characteristic boundary conditions. Generation and development processes of the secondary streamwise vortices in the complicated transitional boundary flow are clearly analyzed based on the of numerical results, and the effects on the formation of the ring-like vortex that is vital to the boundary layer transition are explored. A new mechanism forming the ring-like vortex through the mutual effect of the primary and secondary streamwise vortices is expressed.