Ideal Free Distribution in Two Patches

In this paper, the formats of Julia sets for a class of nonlinear complex dynamic systems with variable coefficients were studied under certain conditions. For the complex dynamic systems in piecewise cases, we proposed some methods to control the forms of their Julia sets and stable domains analytically. What’s more, we illustrated that our methods worked well by computational simulations. Our work provides a better understanding about how to control the Julia sets of certain complex dynamic systems.     

Synthesis and properties of sulfur‐contained poly(silylene arylacetylene)s

Poly(silylene arylacetylene) (PSA) is a kind of poly(arylacetylene) silicon‐containing resins with excellent heat resistance and good mechanical performances. In this article, the sulfur atom is introduced into the main chain of the PSA molecule to obtain a sulfur‐containing poly(silylene arylacetylene), named S‐PSA. By Williamson and Sonogashira reactions, bis(4‐ethynylphenyl)sulfide and bis(4‐ethynylphenyl)sulfone were synthesized. Thereafter, through Grignard reagent way, the poly(silylene ethynylene phenylene sulfide phenylene ethynylene) (PSESE) and poly(silylene ethynylene phenylene sulfone phenylene ethynylene) (PSESO₂E) were synthesized from bis(4‐ethynylphenyl)sulfide, bis(4‐ethynylphenyl)sulfone, and methylphenyl dichlorosilane. Poly(silylene ethynylene phenylene sulfoxide phenylene ethynylene) (PSESOE) was synthesized by the oxidation of PSESE. The structures and properties of these resins were characterized and the mechanical properties of the T300 reinforced composites were tested. The results show that the novel S‐PSA resins have excellent heat resistance and good mechanical properties, and could be used as resin matrices for high‐performance composites in high‐tech fields. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2324–2332     

借助几何图形理解高等数学中的抽象概念和结论

高等数学的很多内容比较抽象,学生不易理解.通过几个例子说明如何将抽象的数学概念和结论与几何图形有机的结合起来,加深对这些概念结论的理解,激发学生的学习兴趣.     

Recent advances in electrochemical water technologies for the treatment of antibiotics: A short review

This short review presents a critical overview of the most recent works published in the literature related to the use of electrochemical advanced oxidation processes (EAOPs) for the treatment of antibiotics present in synthetic and real wastewaters. The first section focuses on novelties within the traditional EAOPs, including electrochemical oxidation and electrochemical Fenton-based processes. The second section is devoted to new electrochemical technologies, including heterogeneous electro-Fenton, electrochemically activated persulfate processes, and combined processes. Future perspectives about these processes are also presented to aid the continuous evolution of research in the area.     

生态平衡制约下离散尺度结构种群的最优收获

研究基于扩展Leslie投影矩阵的离散尺度结构种群模型的最优收获问题,约束条件包括生态平衡和开发成本等.运用凸优化理论证明了最优收获策略的存在性,导出了最优收获模式,应用模型参数给出了收获比率.结论显示:最优策略具有两阶段结构.     

Simple and Efficient Purification Protocol of 9-(Trifluoroacetyl)anthracene from Anthracene

A protocol has been developed to purify 9-(trifluoroacetyl)anthracene from anthracene, the major impurity associated in its synthesis. The protocol utilizes a chemoselective thermal Diels–Alder reaction, employing maleic anhydride as the dienophile. The resulting Diels–Alder adduct can then be removed by extractive workup followed by recrystallization to give 9-(trifluoroacetyl)anthracene with ≥99% chemical purity.     

内蒙五牧场矿区11号煤层原煤大分子结构特征及其形成机制

在对内蒙古自治区呼伦贝尔市伊敏盆地五牧场区11号煤层原煤工业分析、元素分析、¹³C-NMR、FT-IR、XPS等分析基础上,获得了煤大分子结构中碳骨架信息、脂肪结构以及含氧官能团类型及比例、氮原子的存在形式和比例等结构信息。以此为基础,构建了煤的大分子结构模型,并应用 ¹³C-NMR预测软件ACD/CNMR predictor 对其进行了修正, 获得与实验核磁共振谱图吻合较好的大分子结构模型。大分子结构的芳香结构单元以苯、萘、蒽、菲为芳香结构单元,数量分别是1、2、2、1,醚键、氢化芳环以及邻位亚甲基作为连接芳香结构的主要桥键;氧原子以酚羟基、羰基、羧基的形式存在,数量分别是7、3、2;氮原子分别以吡啶和吡咯的形式存在,甲基和脂肪短链分布在芳香单元的边缘。与相邻矿区的褐煤及相近变质程度的神东长焰煤的比较发现,其形成机制主要是在高温低压环境下,热演化过程中快速失去各种含氧官能团,导致短链脂肪类物质的形成,而低压环境则有利于热演化过程中形成的各种小分子物质逸散导致自由基的缩聚,形成较大的芳香结构单元,但是直链脂肪类物质的存在具有位阻效应,不利于芳香结构单元的定向排列,导致所谓的"化学成分成熟超前于其结构成熟"现象。     

航天相机热实验测试系统设计

为了检测航天相机在高低温环境中的电子学性能及可靠性,针对某型号航天相机地面热实验测试需求,设计开发出了一种热实验测试系统,详细介绍了系统的软硬件设计方案及控温策略。系统使用人机交互界面实现热控策略,能实时完成最高80个测试点(160个温度传感器及80路加热器)的控温任务,可以在－30℃～＋50℃范围内对航天相机进行全方位的温度监控,最高控温精度达到0.5℃。经过实际测试验证,系统具有很好的稳定性,能满足航天相机地面热实验的测试需求,工程应用价值高。     

A novel strategy to the synthesis of 4-anilinoquinazoline derivatives

A novel approach to prepare 4-anilinoquinazoline derivatives based on the transformation of indoline-2,3-dione to formamidine was developed. The processes with this approach are simple, efficient, and environmentally friendly. The efficiency of this approach was evaluated by synthesizing 17 4-anilinoquinazolines and comparing the obtained yields with those achievable through conventional synthetic methods. It was the first time that compounds 8d, 8e, 8h, and 13b–f were synthesized. The characteristics of the IR and the UV spectra of these compounds and the effects of their substituents on the spectra were observed.