Electrochemical behavior of uranyl in ionic liquid 1-butyl-3-methylimidazolium chloride mixture with water

Electrochemical behaviors of U(VI) in 1-butyl-3-methylimidazolium chloride (C₄MimCl) with various water contents investigated by chronopotentiometry and cyclic voltammetry. The electrochemical reduction of U(VI) was identified to follow two processes: a lower valence intermediate U(V) was initially formed at the potential of ca. ?0.2 V(vs. Ag wire). Then, further deposition of UO₂ was followed at around ?0.8 V. Little amount of water (1–4 wt%) in C₄MimCl, however, has an effect on the U(VI) reduction by changing the current density of the redox reaction and the diffusion coefficient of U(VI) in C₄MimCl. The deposited product by potentiostatic electrolysis on the surface of stainless steel electrode was characterized by the scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD) methods. Although the electrodeposited black film was amorphous, the electrochemical reduced product of U(VI) can be still confirmed to be UO₂ by XRD after the crystallization of the amorphous deposits at 1,073 K in nitrogen atmosphere.     

散射体排列方式对二维磁振子晶体带隙结构的影响

本文采用平面波展开法数值计算了由铁圆柱分别按正方排列、三角排列以及六角排列在氧化铕基底材料中构成的二维磁振子晶体带结构,讨论了散射体的不同排列方式对磁振子晶体带隙结构的影响.计算结果表明,三角排列散射体的磁振子晶体能够获得最大的自旋波带隙结构. 关键词： 磁振子晶体 带隙 排列方式     

弱激波冲击无膜重气柱和气帘界面的实验研究

研制了一个改进的激波管设备,对马赫数为1.2的弱激波冲击作用下空气中SF6气柱和气帘界面的演变过程进行了初步的实验研究。通过设计激波管实验段、烟雾发生器、气体箱、进气吸气系统和激波管尾段,控制混合气体中SF6的峰值浓度和初始气流速度,建立了稳定、可重复的无膜气柱和气帘初始界面形成技术。利用高速摄影技术,在水平面内观测了气柱和气帘的初始界面图像,沿垂直方向观测了界面RM(Richtmyer-Meshkov)不稳定性的演变过程。气柱演变图像显示了典型的对涡结构,气帘演变图像显示了早期的多蘑菇形结构和后期的相邻波长干扰效应。图像后处理表明,气柱的高度和宽度、气帘的宽度均随时间单调增加,且宽度比高度增加快得多。从二维涡量动力学方程出发,对图像中涡的演变过程进行了初步解释。     

静水压对立方钙钛矿CsSnX3(X=I, Br, Cl)光电性质的第一性原理探究

全无机无铅卤化物钙钛矿已经成为重要的新一代太阳能电池材料.采用密度泛函理论的第一性原理研究了不同静水压下CsSnX₃(X=I, Br, Cl)材料的晶体结构,电子结构和光学性能,并分析了其内在联系.结果表明施加静水压可使材料中Sn-X键长减小,使原子之间的耦合增强,带隙值减小,且随着卤族元素半径的增大,压力效应越明显;随着压力的增加,材料的吸收系数和复折射率增大,吸收光谱出现红移现象,在可见光区和近红外光区吸收增强.相比CsSnBr₃和CsSnCl₃,CsSnI₃在可见光区吸收最佳且受压力作用影响最小,更适用于钙钛矿太阳能电池材料.     

化学课堂中教学自由的不当表现及对策

由于教师对其拥有的教学自由认识不到位,导致教学中存在一些不当表现:利用教材功能的不当;理解教学目标的不当;编辑教辅材料的不当;学习方式引导的不当。为促进教学自由的进一步实现,提出教学建议:教师要勇于担当教学责任、认识教学必然和弘扬教学个性。     

光纤中基于双宽带抽运的受激布里渊散射增益谱展宽及慢光传输中脉冲失真减小的理论研究

分析了单模光纤中双宽带抽运的受激布里渊散射 （stimulated Brillouin scattering,SBS） 光速减慢效应.模拟了两高斯型宽带抽运光同时作用下的SBS增益谱和损耗谱,提出了一种获得均匀增益谱的方法.由于较强抽运光增益谱的中心频率与较弱抽运光损耗谱的中心频率相重合,通过调节较弱抽运光的功率和谱宽,能够部分地抵消掉较强增益谱的顶部从而构建出平坦的增益谱.研究了该平顶增益情形下信号脉冲畸变的性质.与单宽带抽运下脉冲畸变的对比表明,这种产生平顶增益谱的方法能有效地减小脉冲畸变. 关键词： 慢光 受激布里渊散射（SBS） 单模光纤 脉冲失真     

Jet formation in shock-heavy gas bubble interaction

The influences of the acoustic impedance and shock strength on the jet formation in shock-heavy gas bubble interaction are numerically studied in this work. The process of a shock interacting with a krypton or a SF 6 bubble is studied by the numerical method VAS2D. As a validation, the experiments of a SF 6 bubble accelerated by a planar shock were performed. The results indicate that, due to the mismatch of acoustic impedance, the way of jet formation in heavy gas bubble with different species is diversified under the same initial condition. With respect to the same bubble, the manner of jet formation is also distinctly different under different shock strengths. The disparities of the acoustic impedance result in different effects of shock focusing in the bubble, and different behaviors of shock wave inside and outside the bubble. The analyses of the wave pattern and the pressure variation indicate that the jet formation is closely associated with the pressure perturbation. Moreover, the analysis of the vorticity deposition, and comparisons of circulation and baroclinic torque show that the baroclinic vorticity also contributes to the jet formation. It is concluded that the pressure perturbation and baroclinic vorticity deposition are the two dominant factors for the jet formation in shock-heavy gas bubble interaction.     

掺镱石英光纤预制棒的制备与表征

采用改进化学汽相沉积结合溶液掺杂法制备了掺镱石英光纤预制棒,并研究了不同镱掺杂浓度下的吸收光谱和发光光谱.吸收光谱和发光光谱的强度随着YbCl₃溶液浓度的增大而增强.在不产生失透的前提下,得到预制棒芯层能够掺杂的YbCl₃溶液最大浓度为0.057 mol/L.     

低温下JB-9014钝感炸药DSD参数研究

 爆轰冲击波动力学（Detonation Shock Dynamics,DSD）是目前研究爆轰波非理想传播的有效途径。利用DSD的广义几何光学模型,研究了大长径比药柱中爆轰波非理想传播现象,根据-30 ℃下直径为10～30 mm药柱的直径效应实验数据,利用遗传算法确定了低温下JB-9014钝感炸药的DSD参数。由DSD参数计算得到了JB-9014药柱中的定态波形和爆速,计算结果与实验结果符合。