借助紫甘蓝花青素制作彩色水凝胶许愿瓶

以生活中常见的尿不湿、紫甘蓝等为原料，借助尿不湿中的高吸水性树脂颗粒与紫甘蓝中的花青素成分，采用浸渍吸附法制备复合有天然花青素的水凝胶。所构建的水凝胶具有pH响应的特性，能够在不同的酸碱度条件下呈现出不同的颜色。随后，将不同颜色的水凝胶层层堆积于玻璃瓶中，便可制得有良好视觉效果的彩凝胶许愿瓶。该实验贴近生活，简单易实施，具有典型的厨房化学实验特征；同时能够向青少年普及高吸水树脂以及花青素的相关知识原理，提高学生动手操作的能力，培养善于观察生活的习惯。     

Pressure-induced stable structures and physical properties of Sr-Ge system

We have systematically investigated the structures of Sr-Ge system under pressures up to 200 GPa and found six stable stoichiometric structures, they being Sr$_{3}$Ge, Sr$_{2}$Ge, SrGe, SrGe$_{2}$, SrGe$_{3}$, and SrGe$_{4}$. We demonstrate the interesting structure evolution behaviors in Sr-Ge system with the increase of germanium content, Ge atoms arranging into isolated anions in Sr$_{3}$Ge, chains in Sr$_{2}$Ge, square units in SrGe, trigonal units and hexahedrons in SrGe$_{2}$, cages in SrGe$_{3}$, hexagons and Ge$_{8}$ rings in SrGe$_{4}$. The structural diversity produces various manifestations of electronic structures, which is of benefit to electrical transportation. Among them, these novel phases with metallic structures show superconductivity (maximum $T_{\rm c}\sim 8.94$ K for Pmmn Sr$_{3}$Ge). Notably, the n-type semiconducting Pnma SrGe$_{2}$ structure exhibits high Seebeck coefficient and excellent electrical conductivity along the $y$ direction, leading to a high $ZT$ value up to 1.55 at 500 K, which can be potential candidates as high-performance thermoelectrics. Our results will enable the development of fundamental science in condensed matter physics and potential applications in novel electronics or thermoelectric materials.     

Low-Temperature Aqueous Na-Ion Batteries: Strategies and Challenges of Electrolyte Design

Aqueous Na-ion batteries(ANIBs) are considered to be promising secondary battery systems for grid-scale energy storage applications and have attracted widespread attention due to their unique merits of rich resources of Na, as well as the inherent safety and low cost of aqueous electrolytes. However, the narrow electrochemical stability widow and high freezing point of traditional dilute aqueous electrolytes restrict their multi-scenario applications. Considering the charge-storage mechanism of ...