不同杂环取代(E)-β-Farnesene类似物的合成及生物活性研究

为了寻求新型蚜虫控制剂,以蚜虫报警信息素(E)-β-farnesene(EBF)为先导,引入不同类型的杂环取代EBF结构中不稳定的共轭双键,设计合成了一系列不同杂环取代的EBF类似物.所有化合物结构均通过1H NMR、13C NMR、IR及HRMS确证.对化合物进行了生物活性测试及初步构效关系分析.结果表明,所有化合物均对桃蚜和大豆蚜表现出一定的生物活性,部分化合物的杀虫活性优于先导EBF,酯基的引入则对驱避活性有利.     

Formation of Cr(VI) compounds during the thermal decomposition of amorphous chromium hydroxide

Chromium hydroxide (CH) was prepared by the reduction of purified sodium chromate using starch. CH was then used to prepare chromium oxide (Cr₂O₃). Results of thermogravimetric, X-ray diffraction, Fourier transform infrared spectroscopy, and chemical analyses suggested that a small amount of the initial Cr(VI) content speeds up the oxidation and reduction reactions, thereby promoting the purity and crystallization of Cr₂O₃. Cr(VI) in CH induced the evolution of CH and the formation of Cr(VI) containing compounds including CrO₃, NaCr(CrO₄)₂, Cr₃O₈, and Cr₅O₁₂ at low sintering temperature. Furthermore, homogeneous Cr₂O₃ nanoparticles with 99 % purity and particle size of 50 nm were obtained.     

Growth of Hydrophilic CuS Nanowires via DNA‐Mediated Self‐Assembly Process and Their Use in Fabricating Smart Hybrid Films for Adjustable Chemical Release

Facile growth of CuS nanowires through self‐assembly and their application as building blocks for near‐infrared light‐responsive functional films have been demonstrated. It is found that DNA is a key factor in preparing the CuS material with defined nanostructure. An exclusive oriented self‐aggregate growth mechanism is proposed for the growth of the nanowires, which might have important implications for preparing advanced, sophisticated nanostructures based on DNA nanotechnology. By employing the hydrophilic CuS nanowire as an optical absorber and thermosensitive nanogel as guest reservoir inside alginate film, a new platform for the release of functional molecules has been set up. In vitro studies have shown that the hybrid film possesses excellent biocompatibility and the release rate of chemical molecules from the film could be controlled with high spatial and temporal precision. Our novel approach and the resulting outstanding combination of properties may advance both the fields of DNA nanotechnology and light‐responsive devices.     

Synthesis of asymmetrically substituted head‐to‐head polyacetylenes from 2,3‐disubstituted‐1,3‐butadienes

Asymmetrically substituted head‐to‐head polyacetylenes with phenyl and triphenylamine, thienyl or pyrenyl side groups were synthesized through anionic or controlled radical polymerization of 2,3‐disubstituted‐1,3‐butadienes and subsequent dehydrogenation process. Anionic polymerizations of the designed monomers bearing pendent triphenylamine and thienyl group gave narrow disperse disubstituted precursor polybutadienes with exclusive 1,4‐ or 4,1‐structure, which were confirmed by GPC and NMR measurements. In addition, the monomers possessing pyrenyl group were polymerized via nitroxide mediated radical polymerization and the resulting polymers were obtained with controlled molecular weight and low polydispersities. These polybutadiene precursors were then dehydrogenated in the presence of 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone. Thus asymmetrically substituted head‐to‐head polyacetylenes were obtained as indicated by ¹H NMR. The properties of polybutadiene precursors and the corresponding polyacetylenes were analyzed by UV–vis, DSC, and TGA. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 395–402     

A path-oriented encoding evolutionary algorithm for network coding resource minimization

Network coding is an emerging telecommunication technique, where any intermediate node is allowed to recombine incoming data if necessary. This technique helps to increase the throughput, however, very likely at the cost of huge amount of computational overhead, due to the packet recombination performed (ie coding operations). Hence, it is of practical importance to reduce coding operations while retaining the benefits that network coding brings to us. In this paper, we propose a novel evolutionary algorithm (EA) to minimize the amount of coding operations involved. Different from the state-of-the-art EAs which all use binary encodings for the problem, our EA is based on path-oriented encoding. In this new encoding scheme, each chromosome is represented by a union of paths originating from the source and terminating at one of the receivers. Employing path-oriented encoding leads to a search space where all solutions are feasible, which fundamentally facilitates more efficient search of EAs. Based on the new encoding, we develop three basic operators, that is, initialization, crossover and mutation. In addition, we design a local search operator to improve the solution quality and hence the performance of our EA. The simulation results demonstrate that our EA significantly outperforms the state-of-the-art algorithms in terms of global exploration and computational time.