线上线下混合式实验教学模式的改革与探索

大学化学实验课程是培养材料、化学、化工等专业人才应用基本操作和理论解决实际问题的综合性实践训练环节。文章探讨了当前大学化学实验发展由于受到仪器设备大型化、专业化、成本大、更新快等因素限制出现瓶颈,设计了线上线下混合实验教学模式,进行相应的软硬件建设,并开展线上线下混合式实验教学模式的改革与探索。该教学模式具有良好的教学效果,并且可复制可推广,为创新人才的培养和实验教学的创新提供了有益的借鉴。     

Acidity Modification of ZSM-5 for Methane Conversion in Co-feeding Method with MTA Reaction

Acidity plays a vital role in methane conversion by co-feeding method, which is one of the best strategies to improve the utilization and gentle the reaction conditions of methane. In this work, Zn, Ni, Mo, La, Ga, Fe and Co-impregnated ZSM-5 zeolites have been prepared with the same substitutions to variate the acidities and tested in co-aromatization of methanol with methane. It is demonstrated that the new medium-strong acid sites formed by metal and strong acid sites are the key role to activate methane in co-reaction. Zn-modified ZSM-5 catalyst is preferred to exhibit the best methane conversion of 12%, whose aromatic selectivity increases from 27.2% to 52.2% compared with that of HZSM-5. Besides, the addition of methane further improves the production of high-valued aromatics compared with methanol to aromatics (MTA) reaction.     

基于相同参数抛物镜面旋转阵列的太阳能槽式聚光器聚焦特性研究

针对吉林一号某轻型空间遥感相机的任务需求，以碳纤维复合材料的薄壁筒与桁架杆一体式成型为设计思路，基于拓扑优化、尺寸优化以及铺层优化设计了一种高稳定性的次镜支撑结构。工程分析和实验结果表明一体式碳纤维次镜支撑结构具有较好的结构稳定性，整体质量仅为1.3 kg,其在轨成像质量良好，这进一步验证了一体式碳纤维次镜支撑结构的可靠性和设计方法的正确性。     

9-(4-溴丁基)-9H-咔唑的相转移催化合成、表征及室温磷光性能研究——推荐一个大学化学综合实验

推荐了一个大学化学综合实验"9-(4-溴丁基)-9H-咔唑的相转移催化合成、表征及室温磷光性能研究"。实验利用相转移催化合成9-(4-溴丁基)-9H-咔唑分子,采用核磁共振、高分辨质谱和红外光谱对其分子结构进行表征,并利用紫外-可见吸收光谱、稳态/瞬态荧光光谱和密度泛函(DFT)理论计算对其室温磷光性能进行研究。本综合实验涵盖了有机化学、分析化学、物理化学、仪器分析以及理论化学的知识点,建议纳入化学专业高年级综合实验课程。     

Multistable dynamics in a Hopfield neural network under electromagnetic radiation and dual bias currents

Nonlinear Dynamics - This paper investigates a Hopfield neural network under the simulation of external electromagnetic radiation and dual bias currents, in which the fluctuation of magnetic flux...     

Exact synchronization and asymptotic synchronization for linear ODEs

Science China Mathematics - This paper studies exact synchronization and asymptotic synchronization problems for a controlled linear system of ordinary differential equations. In this paper, we...     

Adsorption of Th(IV) from aqueous solution by the graphene oxide nanoribbons/chitosan composite material

Journal of Radioanalytical and Nuclear Chemistry - In order to reduce the potential toxicity to the environment after treatment of radioactive waste water, an eco-friendly graphene oxide...     

Selective Decrosslinking in Liquid Crystal Polymer Actuators for Optical Reconfiguration of Origami and Light‐Fueled Locomotion

The ability to optically reconfigure an existing actuator of a liquid crystal polymer network (LCN) so that it can display a new actuation behavior or function is highly desired in developing materials for soft robotics applications. Demonstrated here is a powerful approach relying on selective polymer chain decrosslinking in a LCN actuator with uniaxial LC alignment. Using an anthracene‐containing LCN, spatially controlled optical decrosslinking can be realized through photocleavage of anthracene dimers under 254 nm UV light, which alters the distribution of actuation (crosslinked) and non‐actuation (decrosslinked) domains and thus determines the actuation behavior upon order‐disorder phase transitions. Based on this mechanism, a single actuator having a flat shape can be reconfigured in an on‐demand manner to exhibit reversible shape transformation such as self‐folding into origami three‐dimensional structures. Moreover, using a dye‐doped LCN actuator, a light‐fueled microwalker can be optically reconfigured to adopt different locomotion behaviors, changing from moving in the laser scanning direction to moving in the opposite direction.     

12β-Acetyloxyperforatin,a New Limonoid from Harrisonia Perforata

A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme.