具有D~6~h对称性的C~3~6及其衍生物电子结构的密度泛函研究

运用密度泛函方法,比较不同水平的基组(HF/6-311+G^*;B3LYP/6-31G^*;B3LYP/6-311+G^*)对具有D~6~h对称性的C~3~6分子进行构型优化的结果,并分析其几何结构、电子结构、稳定性等性质;采用基组B3LYP/6-31G^*对H@C~3~6,Li@C~3~6,Na@C~3~6,K@C~3~6分子进行构型全优化,分析了不同内嵌原子对其几何结构、电子结构、稳定性等性质的影响;首次在B3LYP/6-311+G^*水平上,对C~3~6H~6,C~3~6H~1~2,X@C~3~6(X=H,Li,Na,K)几何构型及电子结构进行研究并得到其稳定性规律。     

Determination of ethambutol by a sensitive fluorescent probe

The competitive reaction between ethambutol and two fluorescent probes (i.e., berberine and palmatine) for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by spectrofluorometry. The CB[7] reacts with these probes to form stable complexes, and the fluorescence intensity of the complexes is greatly enhanced. In addition, the excitation and emission wavelengths of their complexes moved to wavelengths of 343 nm and 495 nm, respectively. However, the addition of ethambutol dramatically quenches the fluorescence intensity of the two complexes. Accordingly, a couple of new fluorescence quenching methods for the determination of ethambutol were established. The methods can be applied for quantifying ethambutol. A linear relationship between the fluorescence quenching values (ΔF) and ethambutol concentration exists in the range of 5.0-1000.0 ng mL(-1), with a correlation coefficient (r) of 0.9997. The detection limit is 1.7 ng mL(-1). The fluorescent probe of berberine has higher sensitivity than palmatine. This paper also discusses the mechanism of fluorescence indicator probes.     

Si-Fe复合SiOx/石墨基负极材料的电化学性能

针对硅氧基负极材料的主要缺陷,在SiO_x/石墨基负极材料中巧妙地引入了Si-Fe、SnO₂合金化合物,以改善其电化学性能,并通过机械球磨、喷雾干燥和高温热解策略制备了一系列硅氧基复合负极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱仪(EDS)和恒流充放电测试仪对复合材料的物相、微观形貌及电化学性能进行了表征。电化学测试结果表明,复合质量分数5% Si-Fe的目标材料充电容量高达443.4 mAh·g^-1,首次库仑效率达75.2%,循环310圈之后容量仍有369.1 mAh·g^-1,容量保持率为81.0%(相对第11圈);同时,经Si-Fe复合之后,锂离子扩散速率得到了明显改善。     

Global analysis of a vector-host epidemic model with nonlinear incidences

In this paper, an epidemic model with nonlinear incidences is proposed to describe the dynamics of diseases spread by vectors (mosquitoes), such as malaria, yellow fever, dengue and so on. The constant human recruitment rate and exponential natural death, as well as vector population with asymptotically constant population, are incorporated into the model. The stability of the system is analyzed for the disease-free and endemic equilibria. The stability of the system can be controlled by the threshold number R₀. It is shown that if R₀ is less than one, the disease free equilibrium is globally asymptotically stable and in such a case the endemic equilibrium does not exist; if R₀ is greater than one, then the disease persists and the unique endemic equilibrium is globally asymptotically stable. Our results imply that the threshold condition of the system provides important guidelines for accessing control of the vector diseases, and the spread of vector epidemic in an efficient way can be prevented. The contribution of the nonlinear saturating incidence to the basic reproduction number and the level of the endemic equilibrium are also analyzed, respectively.     

Generalized projective synchronization of the fractional-order chaotic system using adaptive fuzzy sliding mode control

An adaptive fuzzy sliding mode strategy is developed for the generalized projective synchronization of a fractionalorder chaotic system, where the slave system is not necessarily known in advance. Based on the designed adaptive update laws and the linear feedback method, the adaptive fuzzy sliding controllers are proposed via the fuzzy design, and the strength of the designed controllers can be adaptively adjusted according to the external disturbances. Based on the Lyapunov stability theorem, the stability and the robustness of the controlled system are proved theoretically. Numerical simulations further support the theoretical results of the paper and demonstrate the efficiency of the proposed method. Moreover,it is revealed that the proposed method allows us to manipulate arbitrarily the response dynamics of the slave system by adjusting the desired scaling factor λi and the desired translating factor ηi, which may be used in a channel-independent chaotic secure communication.     

Position difference regularity of corresponding R-wave peaks for maternal ECG components from different abdominal points＊Position difference regularity of corresponding R-wave peaks for maternal ECG components from different abdominal points＊Position difference regularity of corresponding R-wave peaks for maternal ECG components from different abdominal points

We collected 343 groups of abdominal electrocardiogram （ECG） data from 78 pregnant women and deleted the chan- nels unable for experts to determine R-wave peaks from them; then, based on these filtered data, the statistics of position difference of corresponding R-wave peaks for different maternal ECG components from different points were studied. The resultant statistics showed the regularity that the position difference of corresponding maternal R-wave peaks between dif- ferent abdominal points does not exceed the range of 30 ms. The regularity was also proved using the fECG data from MIT-BIH PhysioBank. Additionally, the paper applied the obtained regularity, the range of position differences of the corresponding maternal R-wave peaks, to accomplish the automatic detection of maternal R-wave peaks in the recorded all initial 343 groups of abdominal signals, including the ones with the largest fetal ECG components, and all 55 groups of ECG data from MIT-BIH PhysioBank, achieving the successful separation of the maternal ECGs.     

原子实极化效应和钠原子s系列高Rydberg态能级寿命的计算

利用相关效应的模型势方法计算了钠原子Rydberg态s系列的能级寿命.此理论方法不依赖于实验参数.计算结果很好地符合实验值，并证实了这一理论模型的合理性. 关键词： 原子实极化 Rydberg态 跃迁矩阵元 辐射寿命     

小展弦比调节级三维多目标气动优化设计

大功率汽轮机调节级动叶是典型小展弦比叶片。动叶通道内上下通道涡交汇,流动呈现强烈的三维特性,其设计优化本质上是一个三维优化问题。结合自适应多目标差分进化算法、基于能量法的三维叶片造型方法和RANS方程求解技术,发展了轴流式叶栅三维多目标气动优化设计方法。利用该方法,完成了某典型大功率汽轮机调节级多目标气动优化设计。优化后小展弦比调节级气动性能明显提高,表明该方法具有良好的优化性能和应用前景。     

氦原子Rydberg态10G—10M磁精细结构的计算

通过自洽迭代求解Hartree方程，得到了氦原子1snl组态下的严格数值解波函数，以此构造LS耦合谱项(支项)波函数作为基矢.采用线性变分法，同时考虑交换作用和Breit-Bethe近似下的磁相互作用项，计算了氦Rydberg态10G—10M系列能级的磁精细结构，计算结果很好地符合已有的实验值.对计算方法的进一步改进提出了设想和讨论. 关键词： 氦原子 Rydberg态 磁精细结构 自洽迭代