Pattern transition of two-dimensional Faraday waves at an extremely shallow depth

In this paper, we experimentally investigate the pattern transition of two-dimensional Faraday waves at an extremely shallow depth in a Hele-Shaw cell. Several patterns of Faraday waves are observed, which have some significant differences in wave profile, wave height and wave length. It is found that, in a wide range of the forcing frequency f, there always exists a region of the acceleration amplitude A, in which there exist the so-called hysteretic jumps between different patterns of Faraday waves. All of these experimental observations could enrich our knowledges about the Faraday waves and would be helpful to the further theoretical studies on the related topic in future.     

Stability analysis of neural networks with interval time-varying delays

The global exponential stability is investigated for neural networks with interval time-varying delays. Based on the Leibniz-Newton formula and linear matrix inequality technique, delay-dependent stability criteria are proposed to guarantee the exponential stability of neural networks with interval time-varying delays. Some numerical examples and comparisons are provided to show that the proposed results significantly improve the allowable upper and lower bounds of delays over some existing ones in the literature.     

Selective image encryption using a spatiotemporal chaotic system

A universal selective image encryption algorithm, in which the spatiotemporal chaotic system is utilized, is proposed to encrypt gray-level images. In order to resolve the tradeoff between security and performance, the effectiveness of selective encryption is discussed based on simulation results. The scheme is then extended to encrypt RGB color images. Security analyses for both scenarios show that the proposed schemes achieve high security and efficiency.     

Cesium 6S(1/2) --> 8S(1/2) two-photon-transition-stabilized 822.5 nm diode laser

A cesium 6S(1/2) --> 8S(1/2) two-photon-transition (TPT)-stabilized 822.5 nm diode laser is reported for the first time to our knowledge. Allan deviation of 4.4 x 10(-13) (60 s) was achieved, and the possible systematic errors were evaluated as smaller than 2 kHz. We demonstrate that the cesium TPT-stabilized diode laser could be a reliable frequency reference at 822.5 nm wavelength.     

Exponential stabilization of chaotic systems with delay by periodically intermittent control

This paper studies the exponential stabilization problem for a class of chaotic systems with delay by means of periodically intermittent control. A unified exponential stability criterion, together with its simplified versions, is established by using Lyapunov function and differential inequality techniques. A suboptimal intermittent controller is designed with respect to the general cost function under the assumption that the control period is fixed. Numerical simulations on two chaotic oscillators are presented to verify the theoretical results.     

Highly Emissive 9-Borafluorene Derivatives: Synthesis,Photophysical Properties and Device Fabrication

A series of 9-borafluorene derivatives, functionalised with electron-donating groups, have been prepared. Some of these 9-borafluorene compounds exhibit strong yellowish emission in solution and in the solid state with relatively high quantum yields (up to 73.6 % for FMesB-Cz as a neat film). The results suggest that the highly twisted donor groups suppress charge transfer, but the intrinsic photophysical properties of the 9-borafluorene systems remain. The new compounds showed enhanced stability towards the atmosphere, and exhibited excellent thermal stability, revealing their potential for application in materials science. Organic light-emitting diode (OLED) devices were fabricated with two of the highly emissive compounds, and they exhibited strong yellow-greenish electroluminescence, with a maximum luminance intensity of >22 000 cd m⁻². These are the first two examples of 9-borafluorene derivatives being used as light-emitting materials in OLED devices, and they have enabled us to achieve a balance between maintaining their intrinsic properties while improving their stability.     

三维分等级花状Cd0.8Zn0.2S的结构调控及其光催化CO2还原

近年来,光催化CO2还原被视为一种既能解决能源短缺又能减少温室气体,改善人类生存环境的绿色新型技术.然而,由于CO2气体的相对稳定性,构建高催化活性和高选择性的催化体系仍然面临着巨大挑战.锌硫镉固溶体作为一种廉价的固溶类材料,具有吸光范围适宜、化学性质稳定以及能带结构可调控等特点,在光催化还原CO2的方面表现出巨大的潜力.本文发展了一种简单的原位自组装法合成三维分等级花状结构的Cd0.8Zn0.2S,主要包括Cd^2+和Zn^2+离子在含硫氛围下自组装成核状前体,然后以柠檬酸钠作为形貌诱导剂进一步组装生长,同时控制Cd2+/Zn2+摩尔比和反应时间以实现三维分等级花状Cd0.8Zn0.2S的合成.结果表明,三维分等级花状结构的Cd0.8Zn0.2S在光催化还原CO2的过程中表现出优异的催化活性和稳定性.其中,在光照3 h后,CO产量达到41.4μmol g^?1,大约是相同光照条件下Cd0.8Zn0.2S纳米颗粒的三倍(14.7μmol g^?1).此外,三维分等级花状结构的Cd0.8Zn0.2S在光催化过程中展现出对光催化产物CO的较高选择性(89.9%),其中在没有任何牺牲剂或共催化剂作用下的TON为39.6.太赫兹时域光谱(THz-TDS)表明,这种三维分等级花状结构的Cd0.8Zn0.2S相较于Cd0.8Zn0.2S纳米颗粒更有利于对光的吸收,从而提高对光的有效利用率.原位漫反射傅立叶变化红外光谱表征分析揭示了三维分等级花状结构的Cd0.8Zn0.2S在光催化过程中表面吸附物质以及光催化还原中间体的存在及转化.通过实验数据和理论机理预测表明,该种三维分等级花状结构的Cd0.8Zn0.2S具有较高的电流密度和较好的载流子传输能力.基于这种三维的花状结构,使得Cd0.8Zn0.2S具有较大的比表面积和吸附位点,进一步提升体系的CO2吸附性能和光生电子的转移效率,从而有效提高光催化CO2还原的活性.     

Contradictory effect of gold nanoparticle-decorated molybdenum sulfide nanocomposites on amyloid-β-40 aggregation

The effect of gold nanoparticle-decorated molybdenum sulfide (AuNP-MoS₂) nanocomposites on amyloid-β-40 (Aβ₄₀) aggregation was investigated. The interesting discovery was that the effect of AuNP-MoS₂ nanocomposites on Aβ₄₀ aggregation was contradictory. Low concentration of AuNP-MoS₂ nanocomposites could enhance the nucleus formation of Aβ₄₀ peptides and accelerate Aβ₄₀ fibrils aggregation. However, although high concentration of AuNP-MoS₂ nanocomposites could enhance the nucleus formation of Aβ₄₀ peptides, it eventually inhibited Aβ₄₀ aggregation process. It might be attributed to the interaction between AuNP-MoS₂ nanocomposites and Aβ₄₀ peptides. For low concentration of AuNP-MoS₂ nanocomposites, it was acted as nuclei, resulting in the acceleration of the nucleation process. However, the structural flexibility of Aβ₄₀ peptides was limited as the concentration of AuNP-MoS₂ nanocomposites was increased, resulting in the inhibition of Aβ₄₀ aggregation. These findings suggested that AuNP-MoS₂ nanocomposites might have a great potential to design new multifunctional material for future treatment of amyloid-related diseases.     

High-yield synthesis of a novel water-soluble macrocycle for selective recognition of naphthalene

A novel good water-soluble macrocycle containing two pyridinium moieties was synthesized in high yield.It could form 1:1 complexes with neutral guests containing naphthalene or phenyl units in water.The water-soluble macrocycle can selectively encapsulate naphthalene to form a 1:1 complex over a variety of polycyclic aromatic hydrocarbons.     

Performance enforcement of gel polymer electrolyte for lithium ion battery with co-doping silicon dioxide and zirconium dioxide nanoparticles

In this work, we report a new method to enforce the comprehensive performances of gel polymer electrolyte (GPE) for lithium ion battery. Poly(methyl methacrylate-acrylonitrile-vinyl acetate) [P(MMA-AN-VAc)] is synthesized as polymer matrix. The physical and electrochemical performances of the matrix and the corresponding GPEs, doped with nano-SiO₂ and nano-ZrO₂ particles individually or simultaneously, are investigated by scanning electron microscopy, thermogravimetry, electrochemical impedance spectroscopy, and charge/discharge test. It is found that the membrane co-doped with 5 wt.% nano-SiO₂?+?5 wt.% nano-ZrO₂ and the corresponding GPE combine the advantages of those doped individually with 10 wt.% nano-SiO₂ or 10 wt.% nano-ZrO₂. Accordingly, the comprehensive performances of the membrane and the corresponding GPE, in terms of thermal stability, ionic conductivity, and electrochemical stability on the anode and cathode of lithium ion battery, is enforced by co-doping 5 wt.% nano-SiO₂ and 5 wt.% nano-ZrO₂.