纳米多孔银力学性能表征分子动力学模拟

纳米多孔金属拥有优异的物理、化学性能,在众多领域中极具应用前景.相关力学性能的认知是实现其功能化应用的重要基础之一.基于分子动力学模拟,以三种拓扑结构(立方体结构、金刚石结构、螺旋体结构)的纳米多孔银为对象,研究了单轴拉伸下的力学响应,探讨了拓扑结构和相对密度与其力学性能的内在联系.仿真结果表明,纳米多孔银的极限强度和杨氏模量随相对密度增大而增大的同时,还紧密地依赖于拓扑结构.其中,金刚石结构与螺旋体结构的模量随相对密度的变化趋势较为相近,而螺旋体结构中螺旋形式的孔棱在受力拉直的过程中抵抗变形,表现出相对较好的塑性.立方体结构中,孔棱分布形式单一,抵抗变形的能力较弱,模量值较低.同一相对密度下,金刚石结构的强度最大,立方体结构次之,螺旋体结构最小.金刚石结构中,交错的孔棱间形成三角骨架结构,具有一定的稳定性,表现出相对较高的强度.     

混沌光注入垂直腔面发射激光器混沌输出的时延和带宽特性

提出并仿真论证了利用一个双光反馈垂直腔面发射激光器(定义为主VCSEL,M-VCSEL)产生的混沌光平行单向注入到另一个VCSEL(定义为副VCSEL,S-VCSEL)使所产生的混沌信号的延时特征(TDS)和带宽特性得以优化的技术方案.首先,基于VCSELs自旋反转模型,结合自相关分析方法,通过对系统参量进行优化,可使双光反馈M-VCSEL的X偏振分量(X-PC)和Y偏振分量(Y-PC)均输出混沌信号,且两路混沌信号的平均强度相当、TDS均较弱;在此基础上,将双光反馈M-VCSEL在优化条件下得到的混沌信号平行单向注入到S-VCSEL中,以获得两路TDS得到抑制、带宽更宽的混沌信号.通过考察两个偏振分量输出混沌信号的TDS以及混沌带宽在注入强度和频率失谐构成的参数空间的演化规律,确定了系统获取两路TDS被抑制、宽带宽的混沌信号所需的注入参数范围.     

Multi-party Quantum Key Agreement without Entanglement

A new efficient quantum key agreement protocol without entanglement is proposed. In this protocol, each user encodes his secret key into the traveling particles by performing one of four rotation operations that one cannot perfectly distinguish. In the end, all users can simultaneously obtain the final shared key. The security of the presented protocol against some common attacks is discussed. It is shown that this protocol can effectively protect the privacy of each user and satisfy the requirement of fairness in theory. Moreover, the quantum carriers and the encoding operations used in the protocol can be achieved in realistic physical devices. Therefore, the presented protocol is feasible with current technology.     

Different Kinds of Discrete Breathers in Three Types of One-Dimensional Models

The dynamics of different kinds of discrete breathers in three types of one-dimensional monatomic chains with on-site and inter-site potentials are investigated. The existence and evolution of symmetric breather, antisymmetric breather, and multibreather in one-dimensional models are proved by using rotating wave approximation, local anharmonic approximation, and the numerical method. The linear stability of these breathers is investigated by using Lyapunov stable analysis. The localization and stability of breathers in three types of models correlate closely to the system nonlinear parameter β.     

Gires-Tournois干涉镜补偿色散的自启动飞秒Cr4+:YAG激光器实验研究

利用一片GTI镜补偿腔内色散,并使用宽带半导体可饱和吸收片,实现了锁模自启动的飞秒Cr⁴⁺:YAG激光输出.在9W平均功率的1030nm激光抽运下,获得输出脉冲功率为95 mW,光谱半高全宽45 nm,中心波长1508 nm,实测脉冲宽度为65 fs.     

Synthesis of 6-aryl-5H-quinazolino[4,3-b]quinazolin-8(6H)-one derivatives in ionic liquids catalyzed by iodine

Research on Chemical Intermediates - The iodine-catalyzed reaction of 2-(2-aminophenyl)quinazolin-4(3H)-ones and benzaldehydes was treated in ionic liquids, giving a series of...     

Analysis of Local Structures around Ni Atoms Doped in ZnO-Based Diluted Magnetic Semiconductors by Fluorescence EXAFS

Zn1-xNixO （x = 0.001, 0.01, 0.02, 0.05 and 0.20） powders are prepared by sol-gel method. An extended x-ray absorption fine structure technique （EXAFS） for the Ni K.edge is employed to probe the local structures around Ni atoms doped in ZnO powders by fluorescence mode. The near edge EXAFS of the samples does not change in the range of Ni concentration from x = 0.001 to 0.05, which is consistent with the results of x-ray diffraction of the samples. The simulation results for the first shell EXAFS signals indicated that Ni atoms are substituted in Zn sites.     

Y型分子筛中对称与不对称Co(II)Salen型席夫碱配合物的结构和催化性能

用自由配体法将对称、不对称Co(II)Salen型席夫碱配合物封装于Y型沸石分子筛的超笼中, 并采用FTIR、UV- Vis、热分析和催化技术研究了其空间结构和催化性能. 结果表明, 被封装于分子筛超笼中的Salen型席夫碱配合物, 同样具有未封装配合物的物理化学性能, 也没有影响分子筛的框架结构；在以O2作氧化剂, 催化苯乙烯环氧化反应中表现了非常高的反应活性和稳定性；金属配合物的量子化学密度泛函计算结果揭示了配合物的催化性能与轨道能量密切相关.     

基于散射量子行走的完全图上结构异常搜索算法

完全图K_N 上某个顶点连接到图G将破坏其对称性. 为加速定位这类结构异常, 基于散射量子行走模型设计搜索算法, 首先给出了算法酉算子的定义, 在此基础上利用完全图的对称性, 将算法的搜索空间限定为一个低维的坍缩图空间. 以G为一个顶点的情况为例, 利用硬币量子行走模型上的研究结论简化了坍缩图空间中酉算子的计算, 并借助矩阵扰动理论分析算法演化过程. 针对星图S_N 上结构异常的研究表明, 以星图中心节点为界将整个图分为左右两个部分, 当且仅当两部分在N→∞时具有相同的特征值, 搜索算法可以获得量子加速. 本文说明星图上的分析方法和结论可以推广至完全图的坍缩图上. 基于此, 本文证明无论完全图连接的图G结构如何, 搜索算法均可在O(√N) 时间内定位到目标顶点, 成功概率为1-O(1√N), 即量子行走搜索该类异常与经典搜索相比有二次加速.     

Modulating Cation Migration and Deposition with Xylitol Additive and Oriented Reconstruction of Hydrogen Bonds for Stable Zinc Anodes

Highly reversible plating/stripping in aqueous electrolytes is one of the critical processes determining the performance of Zn-ion batteries, but it is severely impeded by the parasitic side reaction and dendrite growth. Herein, a novel electrolyte engineering strategy is first proposed based on the usage of 100 mM xylitol additive, which inhibits hydrogen evolution reaction and accelerates cations migration by expelling active H₂O molecules and weakening electrostatic interaction through oriented reconstruction of hydrogen bonds. Concomitantly, xylitol molecules are preferentially adsorbed by Zn surface, which provides a shielding buffer layer to retard the sedimentation and suppress the planar diffusion of Zn²⁺ ions. Zn²⁺ transference number and cycling lifespan of Zn ∥ Zn cells have been significantly elevated, overwhelmingly larger than bare ZnSO₄. The cell coupled with a NaV₃O₈ cathode still behaves much better than the additive-free device in terms of capacity retention.