完整系统Appell方程Mei对称性的一种新的守恒量

研究完整系统Appell方程Mei对称性的一种新的守恒量.在群的无限小变换下,由完整系统Appell方程Mei对称性的定义和判据,得到用Appell函数表示的完整系统Appell方程Mei对称性的一种新的结构方程和新的守恒量.最后,举例说明结果的应用.     

Synthesis of indolo [1,2-a]quinoxalines via a Pd-catalyzed regioselective C-H olefination/cyclization sequence

A highly efficient approach to indolo [1,2-a]quinoxaline derivatives through a Pd-catalyzed regioselective C-H olefination/cyclization sequence has been developed. This transformation has a wide range of substrates with various functional groups, and the corresponding heterocyclic products were obtained in good yields.     

经济实用的Boc保护氨基酸键合氯甲基树脂的方法研究

在固相多肽合成中, 探索一种经济有效的Boc保护氨基酸键合氯甲基树脂的方法. 采用K₂CO₃/KI作为键合试剂, 一步合成产物, 反应条件为: Boc保护氨基酸2.5倍量, K₂CO₃ 2.5倍量, KI 0.01倍量, 氯甲基树脂1.0倍量, 普通DMF作反应溶剂, 70 ℃空气浴中旋转反应25 h. 考察了28种不同结构的氨基酸底物在此条件下与氯甲基树脂的键合收率, 大多数氨基酸都能得到几乎定量的酯化产率. 并选取了不同空间位阻的4种Boc保护氨基酸, 比较了KOH, Cs₂CO₃, TEA/KI, DCHA/KI, DIPA/KI, Cs₂CO₃/KI和K₂CO₃/KI等不同键合条件对收率的影响. 结果表明, 除Boc-Asn-OH外, K₂CO₃/KI条件与Cs₂CO₃/KI的效果大体相同, 但K₂CO₃/KI更为经济、可行.     

Determination of methylene blue by resonance light scattering method using silica nanoparticles as probe

A simple and novel method was developed to determine methylene blue(MB) by resonance light scattering(RLS) using silica nanoparticles(SiO_2NPs) as the probe.It was found that MB could enhance the RLS intensity of SiO_2NPs.Moreover,the increase in RLS intensity was linear with the concentration of MB over the range of 0.01-3.0 μg mL~(-1).The limit of detection(LOD) was as low as 4.36 ng mL~(-1)(3σ) and the relative standard deviation(RSD) was 2.4%(n=6).Under the optimum experimental conditions,this proposed method was successfully applied for the determination of MB in aquaculture samples with recoveries between 96.3% and 107%.Possible mechanisms for the RLS enhancement of SiO_2NPs in the presence of MB were also discussed.     

化学互动实验视频的设计与应用——以“氯气的实验室制法”为例

在“氯气的实验室制法”教材内容分析的基础上,利用哔哩哔哩视频平台开发互动实验视频,并在高中化学课堂教学中进行实践应用研究。数据分析结果显示,互动实验视频能够提高学生的学习兴趣和学习成绩,具有推广普及的价值。     

Detection of E.coil O157 ∶ H7 Using Mannose-functionalized Hydrogels

利用伴刀豆球蛋白A(Con A)的多价结合能力,结合水凝胶技术与核酸染色技术发展了一种基于甘露糖功能化的水凝胶检测大肠杆菌(Ecoli) O157∶H7的方法.以过硫酸铵(APS)为催化剂,四甲基乙二胺( TEMED)为加速剂,用丙烯酰胺(AAm)、N,N-二甲基双丙烯酰胺和N-丙烯酰氧琥珀酰亚胺(NAS)合成水凝胶,通过氨基化甘露糖与NAS发生交联反应,制备了甘露糖功能化的水凝胶.当甘露糖功能化的水凝胶加入与Con A共孵育后的菌悬液中时,由于Con A既能与甘露糖特异性结合,又能与E.coli O157∶H7表面的O-抗原发生免疫反应而紧密连接,使目标菌被捕获到水凝胶表面,采用核酸染料SYBR Green Ⅰ对捕获细菌进行染色,实现了对E.coli O157∶H7的核酸标记,最后通过活体荧光成像系统对水凝胶进行荧光成像,从而实现对待测样品的检测.研究结果表明,该方法可应用于缓冲液体系和混合细菌样品中E.coli O157∶H7的特异性检测,且整个检测步骤包括样品预处理可在2h内完成.该方法成本低、易操作,目.具有较好的灵敏度,可检出3.7×101 Cells/mL的目标细菌样品.     

Facile synthesis of indoles by K2CO3 catalyzed cyclization reaction of 2-ethynylanilines in water

The cyclization reaction of 2-ethynyl-N-sulfonylanilides proceeded efficiently in water with the presence of a catalytic amount of K₂CO₃ under transition metal-free condition to give indoles in high yields. The recovery and reusability of the present catalytic system were investigated.     

超小间距纳米柱阵列中的谐振调制

本文首先研究了具有通常柱间距（大于100 nm）的纳米柱阵列在近红外波段的光学特性并实现了通过改变阵列参数（如周期）来调制局域表面等离子体谐振. 随后,通过使用电子束直写和离子束刻蚀的方法制备出具有超小柱间距（小于50 nm）和超高密度（ultrahigh density）的纳米柱阵列并通过对表面等离子体谐振的调制实现了在可见光波段滤出不同颜色的单色光. 本文中所展示的纳米柱功能阵列可以与现有的数字光处理（digital light processing,DLP）技术相兼容进而构造具有超小像素的显示屏,可以在显示、成像等领域取得广泛的应用. 关键词： 纳米柱 超小间距 超高密度 显示     

氧空位和磷掺杂协同增强铁钴基材料电解水催化性能

为了研发高效、稳定的电解水催化剂,我们以氧空位和磷掺杂为基础,通过原位浸泡生长和两步热处理的方法,在泡沫铁上合成具有氧空位和磷掺杂的纳米花结构作为析氢反应(HER)和析氧反应(OER)双功能电催化剂。CoFe₂O₄已被报道为一种很有前途的OER和氧还原反应(ORR)电催化剂,然而CoFe₂O₄在HER中表现出电导率差、电催化反应慢的特性。CoFe₂O₄中氧空位(Ov)的形成可以有效调控催化剂表面的电子结构,有助于产生更多的缺陷和空位,从而提高OER的活性。随后,引入磷原子填充在空位中,制备的P-Ov-CoFe₂O₄/IF在碱性电催化测试中展现出优异的HER和OER性能,在10 mA·cm^-2电流密度下HER和OER过电位仅为54和191 mV,Tafel斜率分别为57和54 mV·dec^-1,并具有良好的循环稳定性。     

Landweber iterative method for an inverse source problem of time-fractional diffusion-wave equation on spherically symmetric domain

In this paper, an inverse source problem of time-fractional diffusion-wave equation on spherically symmetric domain is considered. In general, this problem is ill-posed. Landweber iterative method is used to solve this inverse source problem. The error estimates between the regularization solution and the exact solution are derived by an a-priori and an a-posteriori regularization parameters choice rules. The numerical examples are presented to verify the efficiency and accuracy of the proposed methods.