相对论磁控管中自磁场的影响

针对相对论磁控管中自磁场的产生与分布、自磁场对电子运动的影响以及自磁场对互作用的影响进行了深入分析。分析认为,由于自磁场分布的不对称,自磁场对不同区域电子束的作用不同。加速器一侧的电子束受到更明显的自磁场作用,促使此区域的电子束角向速度增加,直接激化模式竞争。同时,如果阴极比较靠近加速器一侧的1/4区域(距磁控管对称中心大约1/4高度),模式竞争将进一步被激化。     

Lasing mechanism of ZnO nanowires/nanobelts at room temperature

ZnO has become the focus of photonics and optoelectronic research. We prepared pure Mn(II) doped ZnO nanowires with a controlled reduction reaction by carbon in an asymmetrical tube. Careful time-resolved photoluminescence experimental study indicates three types of lasing mechanisms: exciton-exciton interaction, bipolaronic exciton condensation, and plasma; these exist in different ZnO nanowires, which can be changed by doping Mn in ZnO nanowire. The transformation between varied mechanisms is discussed in detail with their spectral behaviors. These results are important in the design of future violet-blue luminescence and display devices.     

Tricritical phenomena in quasi-ternary mixtures of water + n-decane + n-undecane + tert-butanol

Coexistence curves for the quasi-ternary system of water + n-decane + n-undecane + tert-butanol have been determined by measurements of the refractive index in three coexisting liquid phases. The binary mixtures of n-decane + n-undecane constructed the quasi-pure components in which the mass fraction beta of n-decane controls the approach to the tricritical point. The coexistence curves can be fitted to Scott's extended theory and can be extrapolated to a tricritical point at (44.1 +/- 0.3) degrees C and beta = 0.77 +/- 0.02 corresponding to an average n-alkane-carbon number of 10.19 +/- 0.02. The nonclassical critical amplitude ratio has been confirmed to be 4-5% smaller than the classical value, which is consistent with Fisher's prediction.     

Nonvolatile bipolar resistance switching effects in multiferroic BiFeO3 thin films on LaNiO3-electrodized Si substrates

We report on reversible bipolar resistance switching effects in multiferroic BiFeO₃ thin films without electroforming. The BiFeO₃ thin films with (110) preferential orientation were prepared on LaNiO₃-electrodized Si substrates with a Pt/BiFeO₃/LaNiO₃ device configuration. The resistance ratio of high resistance state (HRS) to low resistance state (LRS) of the devices was as high as three orders of magnitude. The dominant conduction mechanisms of LRS and HRS were dominated by ohmic behavior and trap-controlled space charge limited current, respectively. The resistance switching mechanism of the devices was discussed using a modified Schottky-like barrier model taking into account the movement of oxygen vacancies.     

一类带积分边界条件的三阶微分方程边值问题的解

运用Banach压缩映射原理以及Leray-Schauder连续性原理,在非线性项为L1-Caratheodory函数的条件下,研究了一类带积分边界条件的三阶微分方程边值问题解的唯一性、存在性以及解集的紧性.     

Light‐Driven Reversible Intermolecular Proton Transfer at Single‐Molecule Junctions

Photoresponsive molecular systems are essential for molecular optoelectronic devices, but most molecular building blocks are non‐photoresponsive. Employed here is a photoinduced proton transfer (PIPT) strategy to control charge transport through single‐molecule azulene junctions with visible light under ambient conditions, which leads to a reversible and controllable photoresponsive molecular device based on non‐photoresponsive molecules and a photoacid. Also demonstrated is the application of PIPT in two single‐molecule AND gate and OR gate devices with electrical signal as outputs.     

Selective detection of cytochrome C by microchip electrophoresis based on an aptamer strategy

The release of cytochrome C (Cyt C) plays an important role in apoptosis. In this study, selective and sensitive detection of Cyt C based on an aptamer strategy coupled with MCE was developed. Following the binding of a specific aptamer to Cyt C, the aptamer exhibited an irregular state, reducing the binding affinity of a fluorescent probe, and thus preventing the aptamer‐Cyt C complexes from detection within the MCE. The height of the detection peak of the residual aptamer linearly decreased, and therefore, the difference in peak height of residual aptamer compared to that of the initial aptamer was used to quantify the captured protein concentration. Experimental conditions such as incubation time, pH, temperature, and ionic strength were optimized. A measurement of Cyt C concentration by MCE was achieved within 135 s, with a limit of detection as low as 0.4 nM. The proposed method has high selectivity and good stability for the detection of Cyt C. The experimental results demonstrate that this method is quick, consumes only a small quantity of sample, is highly selectivity and exhibits high sensitivity.     

Sulfonium,an Underestimated Moiety for Structural Modification,Alters the Antibacterial Profile of Vancomycin Against Multidrug‐Resistant Bacteria

In the antibiotics arsenal, vancomycin is a last resort for the treatment of intractable infections. However, this situation is under threat because of the increasing appearance of vancomycin‐resistant bacteria (VRB). Herein, we report a series of novel vancomycin derivatives carrying a sulfonium moiety. The sulfonium–vancomycin derivatives exhibited enhanced antibacterial activity against VRB both in vitro and in vivo. These derivatives also exhibited activity against some Gram‐negative bacteria. The sulfonium modification enhanced the interaction of vancomycin with the bacterial cell membrane and disrupts membrane integrity. Furthermore, the in vivo pharmacokinetic profile, stability, and toxicity of these derivatives demonstrated good druggability of the sulfonium–vancomycin analogues. This work provides a promising strategy for combating drug‐resistant bacterial infection, and advances the knowledge on sulfonium derivatives for structural optimization and drug development.     

基于单驱动变量的混沌广义投影同步及在保密通信中的应用

基于单向耦合提出一种只需传递一个驱动变量实现混沌系统广义投影同步方法.通过改变广义投影同步的比例因子,获得任意比例于原驱动混沌系统输出的混沌信号.由于只需传递一个信号,比起已有的方法具有更高的实用价值,理论推导和数值仿真进一步表明了该方法的有效性.最后,基于统一混沌系统的广义投影同步,给出了一种安全性更好的混沌保密通信方案. 关键词： 混沌系统 单驱动变量 广义投影同步 统一混沌系统