搅拌棒吸附萃取技术

搅拌棒吸附萃取技术的提出至今已有二十年,其源于固相微萃取,却有更高的固定相体积、萃取容量和萃取回收率。搅拌棒吸附萃取作为一种高效的样品前处理方法,广泛应用于环境样品、食品样品、药物样品和挥发性物质的分离富集。搅拌棒的核心是涂层,目前已有商品化涂层、自制分子印迹聚合物涂层和自制非印迹涂层。本文介绍了搅拌棒吸附萃取的基本原理,系统评述了各种搅拌棒吸附萃取涂层的发展和应用研究进展,并介绍了一些新颖的搅拌棒萃取模式,最后对搅拌棒吸附萃取技术的发展进行了总结和展望。     

Synthesis of Low‐Dimensional Polyion Complex Nanomaterials via Polymerization‐Induced Electrostatic Self‐Assembly

Nanostructured polyion complexes (PICs) are appealing in biomaterials applications. Yet, conventional assembly suffers from the weakness in scale‐up and reproducibility. Only a few low‐dimensional PICs are available to date. Herein we report an efficient and scalable strategy to prepare libraries of low‐dimensional PICs. It involves a visible‐light‐mediated RAFT polymerization of ionic monomer in the presence of a polyion of the opposite charge at 5–50 % w/w total solids concentration in water at 25 °C, namely, polymerization‐induced electrostatic self‐assembly (PIESA). A Vesicle, multi‐compartmental vesicle, and large‐area unilamellar nanofilm can be achieved in water. A long nanowire and porous nanofilm can be prepared in methanol/water. An unusual unimolecular polyion complex (uPIC)‐sphere‐branch/network‐film transition is reported. This green chemistry offers a general platform to prepare various low‐dimensional PICs with high reproducibility on a commercially viable scale under eco‐friendly conditions.     

Blow-up criteria and periodic peakons for a two-component extension of the μ-version modified Camassa-Holm equation

Some two-component extensions of the modifiedμ-Camassa-Holm equation are proposed.We show that these systems admit Lax pairs and bi-Hamiltonian structures.Furthermore,we consider the blow-up phenomena for one of these extensions(2μmCH),and the periodic peakons of this system are derived.     

Construction of a 2D Graphene‐Like MoS2/C3N4 Heterojunction with Enhanced Visible‐Light Photocatalytic Activity and Photoelectrochemical Activity

A novel graphene‐like MoS₂/C₃N₄ (GL‐MoS₂/C₃N₄) composite photocatalyst has been synthesized by a facile ethylene glycol (EG)‐assisted solvothermal method. The structure and morphology of this GL‐MoS₂/C₃N₄ photocatalyst have been investigated by a wide range of characterization methods. The results showed that GL‐MoS₂ was uniformly distributed on the surface of GL‐C₃N₄ forming a heterostructure. The obtained composite exhibited strong absorbing ability in the ultraviolet (UV) and visible regions. When irradiated with visible light, the composite photocatalyst showed high activity superior to those of the respective individual components GL‐MoS₂ and GL‐C₃N₄ in the degradation of methyl orange. The enhanced photocatalytic activity of the composite may be attributed to the efficient separation of electron–hole pairs as a result of the matching band potentials between GL‐MoS₂ and GL‐C₃N₄. Furthermore, a photocatalytic mechanism for the composite material has been proposed, and the photocatalytic reaction kinetics has been measured. Moreover, GL‐MoS₂/C₃N₄ could serve as a novel sensor for trace amounts of Cu²⁺ since it exhibited good selectivity for Cu²⁺ detection in water.