Higher Dimensional Unified Description of Early Universe with Variable <Emphasis Type="Italic">G</Emphasis> and Λ

A homogeneous and isotropic Friedmann-Robertson-Walker (FRW) model with varying gravitational and cosmological constant is studied in the context of higher dimensional space time. Exact solution of the field equations are obtained by using the “gamma law” equation of state p=(γ−1)ρ, where γ is adiabatic parameter varies continuously as the universe expands. The functional form γ which is assumed to be the function of scale factor R as proposed by Carvalho (1996) is used to analyse the behavior of scale factor R, cosmological constant Λ and the gravitational constant G for two different phases: inflation and radiation. The various physical aspects of the early cosmological models has also been discussed in the framework of higher dimensional space time.     

Dispersive shock waves in three dimensional Benjamin–Ono equation

Dispersive shock waves (DSWs) in the three dimensional Benjamin–Ono (3DBO) equation are studied with step-like initial condition along a paraboloid front. By using a similarity reduction, the problem of studying DSWs in three space one time (3+1) dimensions reduces to finding DSW solution of a (1+1) dimensional equation. By using a special ansatz, the 3DBO equation exactly reduces to the spherical Benjamin–Ono (sBO) equation. Whitham modulation equations are derived which describes DSW evolution in the sBO equation by using a perturbation method. These equations are written in terms of appropriate Riemann type variables to obtain the sBO-Whitham system. DSW solution which is obtained from the numerical solutions of the Whitham system and the direct numerical solution of the sBO equation are compared. In this comparison, a good agreement is found between these solutions. Also, some physical qualitative results about DSWs in sBO equation are presented. It is concluded that DSW solutions in the reduced sBO equation provide some information about DSW behavior along the paraboloid fronts in the 3DBO equation.     

Multilayered 2D Cesium-Based Hybrid Perovskite with Strong Polarization Sensitivity: Dimensional Reduction of CsPbBr3

3D perovskite CsPbBr₃ has recently taken a blooming position for optoelectronic applications. However, due to the lack of natural anisotropy of optical attributes, it is a great challenge to fulfil polarization-sensitive photodetection. Here, for the first time, we exploited dimensionality reduction of CsPbBr₃ to tailor a 2D-multilayered hybrid perovskite, (TRA)₂CsPb₂Br₇ ( 1 , in which TRA is (carboxy)cyclohexylmethylammonium), serving as a potential polarized-light detecting candidate. Its unique quantum-confined 2D structure results in intrinsic anisotropy of electrical conductivity, optical absorbance, and polarization-dependent responses. Particularly, it exhibits remarkable dichroism with the photocurrent ratio (I_pc/I_pa) of ≈2.1, being much higher than that of the isotropic CsPbBr₃ crystal and reported CH₃NH₃PbI₃ nanowire (≈1.3), which reveals its great potentials for polarization-sensitive photodetection. Further, crystal-based detectors of 1 show fascinating responses to the polarized light, including high detectivity (>10¹⁰ Jones), fast responding time (≈300 μs), and sizeable on/off current ratios (>10⁴). To our best knowledge, this is the first study on 2D Cs-based hybrid perovskite exhibiting strong polarization-sensitivity. The work highlights an effective pathway to explore new polarization sensitive candidates for hybrid perovskites and promotes their future electronic applications.     

基于真实问题解决的高三复习课——以电解NaCl溶液的深入学习为例

围绕电解NaCl溶液，高三复习课以能力素养的落实为目标，选择真实的问题情境，开展分析解释、推论预测、设计评价等学习活动，外显学生对电解原理的理解，矫正学生的偏差认识，发展学生对电解NaCl溶液的深入理解，促进核心素养的真正落实。     

中学化学教材中化学方程式内容的编排分析——基于“三序结合”的视角

利用“三序结合”的原则分析了人教版初中和高中不同阶段“化学方程式”知识的编排情况，人教版教材对这部分知识的编排较好地符合了知识的逻辑顺序、学生的认识顺序和学生的心理发展顺序相结合的要求。同时，还针对教材分析给出了教学建议。     

Antimicrobial active packaging combining essential oils mixture: Migration and odor control study

Thymol is an essential oil (EO), known to have excellent antimicrobial (AM) properties and can potentially be used as an active agent in AM food packages. Mixing Thymol with other EOs may help to reduce the organoleptic impact of its strong odor. In the present study, the effect of thymol, carvacrol, citral, and eugenol binary mixtures on the AM activity, migration over time, and sensory properties of polypropylene (PP)/polyamide (PA)/nanoclays composite blends active package (AP) films was examined. The release of different EOs from the polymer film was found to have a direct correlation with the odor perception of thymol. Varied EOs bearing films have shown different capacity to inhibit bacterial growth over time (Escherichia coli). Lastly, the inhibition of fungal growth on food sample using EO‐loaded films was obtained for over 50 days, indicating the potential use of the developed films as active food packaging.     

Solutions with time-dependent singular sets for the heat equation with absorption

We consider the heat equation with a superlinear absorption term ${?}_{t}u?\mathrm{\Delta }u=?u^p$ in ${\mathbb{R}}^n$ and study the existence of nonnegative solutions with an m-dimensional time-dependent singular set, where $n?m\ge 3$. We prove that if $1<p<(n?m)/(n?m?2)$, then there are two types of singular solutions. Moreover, we show the uniqueness of the solutions and specify the exact behavior of the solutions near the singular set.     

基于OLED器件的封装方法研究

有机电致发光二极管(Organic Light-Emitting Diode,OLED)显示因其全固态、自发光、具有高发光效率等优点,市场占有率逐年提高。然而,可靠封装仍然是困扰OLED显示领域的关键技术问题之一。首先从常见的OLED封装方法展开讨论,分析了各种结构特点与缺陷,其次论述了具有广大发展前景的薄膜封装技术封装结构发展历程,以及封装结构的改进。最后对目前常见的无机薄膜制备工艺与有机薄膜制备工艺进行了归纳对比,并对薄膜封装的发展提出了展望。