对现行中学化学课本中部分实验的改进和补充

《中学化学教学大纲》(试行草案)指出“加强实验教学是提高教学质量的重要一环。”要求教师“努力完成规定的实验。”为了提高实验教学的质量,教师对每个实验应作深入研究,我在教学实践中,对现行课本中的一部分实验作了改进和补充。     

压强对化学平衡的影响的实验

高中化学课本第一册,[实验5—5]压强对化学平衡的影响,用注射器做课堂演示实验,因容器小,现象不大明显,无法使全班学生都看得清。我们设计一套实验装置,经教学实践证明,效果很好。     

Biodegradable and flexible l-carrageenan based RRAM with ultralow power consumption

Transient memories, which can physically disappear without leaving traceable remains over a period of normal operation, are attracting increasing attention for potential applications in the fields of data security and green electronics. Resistive random access memory(RRAM) is a promising candidate for next-generation memory. In this context, biocompatible l-carrageenan(l-car), extracted from natural seaweed, is introduced for the fabrication of RRAM devices(Ag/l-car/Pt).Taking advantage of the c...     

LaAlO_3∶Eu~(3+)的绿色化学合成及光谱性质

提出一种合成LaAlO3的新方法,该方法操作简单、成本低、无污染。将化学计量比的反应物La(OH)3/La2O3和Al(OH)3放入反应釜中,于220℃温度下水热活化处理,快速加热至900℃反应即可得到LaAlO3。XRD结果表明,所合成的LaAlO3为三方晶系。PL结果表明,所合成的LaAlO3∶Eu3+的主要发射为Eu3+的5D0→7F1磁偶极跃迁发射和5D0→7F2电偶极跃迁发射,红橙比随着Eu3+离子掺杂量的增加而变大。在VUV-UV激发光谱中,LaAlO3∶Eu3+位于VUV光谱区的基质吸收很弱,而位于~315 nm的O2--Eu3+的电荷迁移跃迁带(CT)则较强。     

叶绿素稀土配位结构的EXAFS研究: 镧叶绿素a双层夹心分子 结构的确认

通过合成镧叶绿素a(La-Chla),研究稀土在叶绿素中的赋存状态。La-Chla的紫外可见光谱(UV-vis)、红外光谱(FT-IR)证实,镧离子已配位到叶绿素a的卟啉环上。其磁圆二色谱(MCD)在Soret带具有双层夹心卟啉结构的特征结构。通过扩展X射线吸收精细结构谱(EXAFS),采用双层夹心结构模型拟合,确定La周围的近邻结构,取得满意结果。表明合成镧叶绿素a具有双层夹心结构。La夹于两个卟啉环之间,与上下卟啉环上共八个N原子配位,La-N平均键长0.261nm。     

Gd203：（Ce^3 ，En^3 ）微晶中稀土离子间的级联能量传递

本文报道了纳米Gd203：(Ce^3 ,En^3 )的紫外与真空紫外（UV-VUV)激发谱及其选择激发下的荧光光谱。这些光谱实数表明,除了Gd2O3基质与Ce^3 ,Eu^3 离子之间的能量传递外,还存在着Gd^3 与Ce^3 、Eu^3 间的能量传递,即存在Gd^3 →Ce^3 →Eu^3 三种稀土离子间的级联传递。     

Fluorescence lifetime measurement from a designated single-bunch in the BEPCⅡ colliding mode

Fluorescence lifetime measurement in the time domain requires excitation from a well separated single bunch using synchrotron light sources. In the colliding mode of the Beijing Electron Positron Collider Ⅱ (BEPCⅡ), a hybrid filling pattern was realized such that a single bunch was placed in the middle of a large gap between two multi-bunch groups. Detection of fluorescence lifetime, based on the excitation of the light pulse from this designated single-bunch, was established at Beamline 4B8 of the Beijing Synchrotron Radiation Facility (BSRF). The timing signal of the BEPCII was utilized as a trigger to gate this fluorescence event. L-Tryptophan amino acid, a known lifetime standard, was selected to assess the lifetime measurement performance. The measured lifetime was consistent in both colliding and single-bunch mode with the time resolution down to 450 ps. Moreover, both the bunch purity and the fine structure of the hybrid filling pattern were characterized.     

AlSb掺Mn、Fe的电子结构和光学性质

本文基于第一性原理平面波赝势(PWP)和广义梯度近似(GGA)方法,对闪锌矿型AlSb的超晶胞、掺入杂质Mn和Fe超晶胞进行结构优化处理。计算了三种体系下AlSb超晶胞的电子结构、Mullkien电荷数和光学性质,详细研究了其能带结构、电子态密度、电荷布局分布和光学性质。结果表明：在Mn,Fe掺杂AlSb体系中,由于空穴密度的增加,禁带宽度减小,材料表现出半金属行为,且在可见光区电子跃迁明显增强。     

折扣加权总完工时间问题的半在线排序算法

讨论到达时间任意,加工时间具有上下限约束,目标函数为带折扣的加权总完工时间的单机排序问题1|rj,Pmin≤Pj≤Pmax|∑ωj(1-e-βCj),给出了此问题在任意半在线算法下的竞争比下界,并提出了求解此问题的一种半在线算法D-αWDSPT,通过分析算法竞争比说明该算法是一种近似最优算法.同时指出,算法在问题的三种特殊情况下是最优算法.第一种问题是最小加工时间P→0,第二种问题是折扣因子β→0,第三种问题是工件加工时间相同Pmin=Pmax