Copper‐Catalyzed Intramolecular Desymmetric Aryl C?O Coupling for the Enantioselective Construction of Chiral Dihydrobenzofurans and Dihydrobenzopyrans

O‐Heterocyclic structures such as 2,3‐dihydrobenzofurans are key motifs in many natural compounds and pharmaceuticals. Enantioselective formation of chiral dihydrobenzofurans and analogues was achieved through a copper‐catalyzed desymmetrization strategy with a chiral cyclic 1,2‐diamine. A broad range of substrates are compatible with this Cu^I‐diamine catalytic system and afford the desired coupling products with chiral tertiary or quaternary carbon centers in high yields and good to excellent enantioselectivities under mild conditions.     

线性随机分数阶微分方程Euler方法的弱收敛性与弱稳定性

本文主要研究了线性随机分数阶微分方程Euler方法的弱收敛性与弱稳定性.首先构造了数值求解线性随机分数阶微分方程的Euler方法,然后证明该方法是弱稳定的和α阶弱收敛的,文末给出的数值算例验证了所获得的理论结果的正确性.     

高温共电解H2O/CO2制备清洁燃料

高温共电解(high temperature co-electrolysis,HTCE)H2O和CO2技术是一种很有前景的清洁燃料制备和CO2减排新技术。该技术可利用可再生能源或核能提供的电能和高温热,通过高温固体氧化物电解池(solid oxide electrolysis cell,SOEC)将H2O和CO2共电解生产合成气(H2+CO),再将制备的合成气用于生产各种液态碳氢燃料。本文详细介绍了利用高温固体氧化物电解池共电解H2O和CO2制备合成燃料的基本原理、发展历程和目前世界各国的研究进展,对该技术的优势和特点进行了分析,并对该技术在关键材料、反应机理等方面存在的问题进行了总结和讨论,最后对其在新能源技术领域的应用前景作了展望。     

共价有机框架材料在固定化酶及模拟酶领域的应用

共价有机框架(Covalent Organic Frameworks, COFs)是一类由轻质元素通过可逆共价键连接而成的晶型多孔有机材料。因具有高比表面积、低密度、规则的孔隙和易于功能化等独特的性能和结构,COFs在气体吸附、化学传感和非均相催化等领域有着广泛的应用前景。近年来,COFs逐渐显现出在固定化酶和模拟酶领域的应用潜力,由于可以轻松定制COF上的官能团以保持COF与酶之间的特定相互作用,因此COF成为有吸引力的酶固定基质。此外,COF的连续且封闭的开放通道为渗透酶提供了良好的微环境。同时,探索了COF模拟酶的特征,通过“从下到上”的方法或后修饰策略设计了COF模拟酶。这不仅扩展了固定化酶载体材料的研究和应用范围,还为模拟酶仿生催化提供了新的研究思路。本文综述了COFs固定化酶和作为纳米材料模拟酶(纳米酶)在生物催化领域的研究进展,详细讨论了COFs载体的合成和功能化策略、固定化酶方式,以及COFs纳米酶的设计理念、催化活性和选择性等内容。最后总结了目前COFs在酶催化领域所面临的挑战和未来发展的机遇。     

One-Pot Synthesis of 4-Substituted 2-Thio-5-oxo-1,3,6-thiadiazaoctane

4-Substituted 2-thio-5-oxo-1,3,6-thia-diazaoctanes have been prepared in one pot by the reaction of α-amino acid aster hydrochlorides with carbon disulfide and 2-bromoethylamine hydrobromide in the presence of triethylamine.     

非线性刚性变延迟微分方程单支方法的数值稳定性

现有文献中对于非线性延迟微分方程渐近稳定性及其数值方法的稳定性研究大都局限于常延迟的情形,例如可参见匡蛟勋[1-3],黄乘明[4],Torelli[5]等人的大量工作.1994年A.Iserles[6] 首次研究了比例延迟微分方程数值方法的线性稳定性,随后有相当多的文献对比例延迟微分方程的各种数值方法的线性稳定性进行了讨论.1997年Zennaro[7]首次研究了非线性刚性变延迟微分方程的渐近稳定性,但该文中对于延迟量的限制十分苛刻,同时该文也首次研究了非线性刚性变延迟微分方程Runge-Kutta方法的非线性稳定性. 本文目的是试图在上述基础上进一步研究非线性刚性变延迟微分方程的渐近稳定性及其数值方法的稳定性.首先在第二节我们给出了非线性刚性变延迟微分方程模型问题（2.1）渐     

Novel Scheme for Narrow Band Fiber Filter System

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Synthesis of core-shell polymer microspheres by two-stage distillation-precipitation polymerization

Narrow- or monodisperse core-shell polymer microspheres with a dense core and a lightly crosslinked shell with different functional groups, such as ester, hydroxyl, cyano, were prepared by two-stage distillation-precipitation polymerization without any stabilizer. Commercial divinylbenzene (DVB), containing 80% of DVB was polymerized by distillation-precipitation polymerization with 2,2′-azobis(2-methyl propionitrile) (AIBN) as initiator in neat acetonitrile in the absence of any stabilizer as the first stage polymerization and used as the core. When the conversion of DVB was about 35% in the first stage, the second-comonomers with different functional groups, such as methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), 2-hydroxyethyl methacrylate (HEMA), i-octyl acrylate (i-OA), dodecyl acrylate (DA), methyl acrylate (MA), ethyl acrylate (EA), ethylene glycol dimethacrylate (EGDMA), triethyleneglycol dimethacrylate (TEGDMA), trimethylolpropane trimethacrylate (Trim), and acrylnitrile (AN) together with AIBN were introduced, respectively, into the reaction system and copolymerized with unreacted DVB on the core surface to form a lightly crosslinked functional shell. The resulting core-shell polymer particles were characterized with scanning electron microscopy (SEM) and FT-IR spectra.     

高温固体氧化物电解水制氢技术

高温水蒸气电解制氢是解决大规模氢源问题的潜在途径之一。高温固体氧化物电解池（SOEC）可以利用各种可再生能源以及先进核能提供的热能和电能,在高温下将水蒸气高效电解为氢气和氧气。SOEC结合先进核能可以实现高达50％的热氢转化效率,已经成为近年来能源领域的一个研究热点。本文较详细介绍了SOEC的原理、分类、组成材料和特点,综述了SOEC制氢的发展现状、关键材料和核心技术,展望了SOEC在先进能源技术领域的应用前景。     

Synthesis of a novel fluorescent probe and investigation on its interaction with nucleic acid and analytical application

A novel fluorescent probe N-(N-(2-(4-morpholinyl)ethyl)-4-acridinecarboxamide)-alpha-alanine (N-(N-(ME)-4-ACA)-alpha-ALA) was synthesized. The structure was characterized by 1H NMR, MS, elemental analysis, fluorescent and ultraviolet spectra. This new compound exhibited high binding affinity to DNA, intense fluorescence and high water solubility. Experiment indicated that the fluorescent intensity was quenched when DNA was added. A method for DNA determination based on the quenching fluorescence (lambda(ex)=258nm, lambda(em)=451nm) of N-(N-(ME)-4-ACA)-alpha-ALA was established. Under optimal conditions (pH 7.2, CN-(N-(ME)-4-ACA)-alpha-ALA)=3 x 10(-6) mol L(-1)), the linear range is 0.1-4.0 microg mL(-1) for both fish semen (fsDNA) and calf thymus DNA (ct-DNA). The corresponding determination limits are 4.6 ng mL(-1) for fsDNA and 5.1 ng mL(-1) for ct-DNA, respectively. The relative standard deviation is 1.0%. Thus this compound can be used as a DNA fluorescent probe. The experiments proved that the interaction mode between N-(N-(ME)-4-ACA)-alpha-ALA and DNA was groove binding. The modified Rosenthal's graphical method gave the binding constant of 1.0 x 10(6) L mol(-1) and a binding size of 0.31 base pairs per bound drug molecule.