Ultrasound-assisted Extraction of Kamebakaurin from Rabdosia excisa by Response Surface Methodology

For the efficient extraction of kamebakaurin（KA）, the ultrasound-assisted extraction（UAE） of KA from Rabdosia excisa（R, excisa） via response surface methodology（RSM） was investigated with high-performance liquid chromatography（HPLC）. Effects of the experimental parameters such as extraction solvent, ratio of liquid to plant material, extraction time and extraction temperature on the extracting efficiency of KA from R. excisa were evaluated, and the purity of KA in residual was calculated. The optimized conditions were 65.5%（volume fraction） acetone, 35 ℃, time of 24.6 min with ultrasound of 80 W/L, 40 kHz, ratio of liquid to plant material at 30：1（mL/g）. The maximum yield of KA is 0.708 mg/kg, with mean purity of 6.09%, indicating that ultrasound-assisted extraction is a feasible and useful method for extracting KA from R. excisa.     

苯/二联苯为桥的噻吩-吡咯-噻吩结构:分子构型及电致变色性质

A series of multi-branched dithienylpyrrole (SNS) monomers with rigid phenyl (PhSNS) and biphenyl rings (BPhSNS) as bridges were designed and synthesized, and were fabricated to form cross-linked polymers (pPhSNS, pBPhSNS) by electrochemical polymerization. Cyclic voltammetry (CV) results showed that PhSNS and BPhSNS exhibited similar oxidative properties except for one new higher-potential oxidative peak appearing in the curves of PhSNS. Theoretical calculations indicated that it should be attributed to the different steric configuration between the two dithienylpyrrole (SNS) units in PhSNS. One SNS unit possessed a larger twist angle (40.2°) between thiophene and pyrrole rings than the other one (21.2°), which indicated that PhSNS possessed a relatively larger energy gap (~0.4 eV) between HOMO-1 and HOMO than BPhSNS, for which HOMO and HOMO-1 levels were of almost the same energy. However, both PhSNS and BPhSNS showed similar onset oxidation potentials. The CV curves of pPhSNS and pBPhSNS showed that they presented similar oxidative properties, which enabled their corresponding electrochemical polymers to exhibit similar electrochromic properties. The UV-vis spectra of the corresponding polymers showed that both pPhSNS and pBPhSNS possessed similar optical absorption and similar multicolor switching between yellow (-0.8 V), greyish-green (0.9 V) and gray (1.1 V) colors. Besides, pPhSNS and pBPhSNS showed fast switching times of 0.57 s and 0.93 s at 1100 nm, respectively and reasonable contrasts of 46% and 31% at 1100 nm, respectively. These investigations may help understand the relationship between structural configuration and the electrochemistry/electrochromic properties for polymer electrochromic (PEC) materials research.     

人教版高中化学教科书“研究与实践”栏目分析与实施策略*

对人教版高中化学教科书新设计的“研究与实践”栏目的主题内容、功能价值进行分析,就如何充分发挥该栏目的教学功能和价值,发展学生的化学学科核心素养,提出了创设教学情境线索、开发为研究性学习课题、开发为校本选修课程、开发为STEM课程等实施策略。     

安福县铁丝岭夏季鸟类群落结构

2012年6～7月,通过对江西吉安市安福县铁丝岭夏季鸟类群落结构进行了调查,总共观察到507只鸟类个体,隶属于10目,25科,52种。其中雀形目和鹳形目鸟类在个体数量和种类上都占据了绝对优势地位,树麻雀和池鹭为其中的绝对优势种。在居留型组成上,留鸟无论在个体数量分布还是种数分布都占最高比例,分别占据全部鸟类的69%和81%。铁丝岭地区鸟类群多多样性指数为3.27,均匀性指数为0.83。在调查的五个鸟类生境中,常绿阔叶林鸟类群落多样性最高,为2.79,而水库群落的均匀性指数最高,达到0.94。另外,随着海拔的升高,鸟类种类和数量都表现明显下降的趋势。总之,栖息地生境生产力的差异在很大程度上决定了不同生境鸟类分布的特点,而栖息地的相似性则决定了鸟类群落组成的相似程度。     

随动系统数字化改装中PWM系统的研究

描述了一个随动系统数字化改装中 PWM系统的研究 ,并给出了计算机辅助分析的程序流程图 ,为类似装备的数字化改造提供了有效的参考     

基于改进克隆卡尔曼滤波的视觉惯性里程计实现

视觉-惯性多传感器融合方案可以有效解决GNSS据止环境下的导航问题。为了更有效地处理视觉的相对观测信息,文中研究并实现了一种基于克隆卡尔曼滤波(stochastic cloning Kalman Filter,SCKF)与滑动窗方法相结合的低成本视觉惯性里程计紧耦合算法。开源数据集实验表明,文中算法精度超过了多状态约束卡尔曼滤波(MSCKF)开源代码的效果。     

基于比较教学法的FIR数字滤波器设计实验

数字滤波器设计是"数字信号处理"课程实验教学的重要内容,本文讨论了以Matlab仿真软件为设计FIR数字滤波器的三种手段:按照窗函数设计法的原理编程设计滤波器、采用Matlab信号处理工具箱提供的fir1函数设计滤波器和调用滤波器设计工具箱提供的图形用户界面设计滤波器.教学效果表明,采用比较教学法深化了学生对滤波器设计...     

复周期结构光子晶体的光子能带特性研究

本文构思了一种每个周期内部有几个不同的小单元的复周期结构光子晶体，并利用光学传输矩阵法对这种光子晶体进行了数值模拟计算。计算结果表明，这种复周期结构光子晶体比普通结构的光子晶体多出1个大的光子禁带区。适当调整参数还可以分别获得多通道窄带滤波特性、带通滤液特性和窄带透过特性。     

基于无人机中继的星地认知网络波束成形算法

针对基于无人机中继的星地认知网络,提出了两种波束成形（beamforming, BF）算法,通过对各种干扰进行抑制,实现系统间的频谱共享。具体而言,在基于无人机中继的卫星网络作为次级网络、地面网络作为主网络的情况下,以无人机最大发射功率和主用户所受干扰为约束条件,建立次级用户信干噪比最大化准则的优化问题;接下来在已知次级用户统计信道状态信息的条件下,提出一种基于迭代的BF算法对优化问题进行求解;更进一步,为了降低迭代算法的实现复杂度,提出了一种基于迫零的BF算法。最后,计算机仿真验证了所提两种波束成形方案的正确性与有效性。     

Design of a multi-cusp ion source for proton therapy

The permanent magnets of the discharge chamber in a multi-cusp proton source are studied and designed. The three electrode extraction system is adopted and simulated. A method to extract different amounts of current while keeping the beam emittance unchanged is proposed.