Synthesis and properties of novel photochromic bisthienylethenes containing imidazole and imidazolium derivatives

A series of bisthienylethenes containing imidazole and imidazolium derivatives have been prepared and the products have been characterized by means of NMR and MS.Their photochromic and fluorescent switch properties have been investigated by UV–vis absorption spectra and fluorescence spectra.The fluorescent emissions of these kinds of photochromic compounds can be simply modulated by varying the imidazole groups,which shows that these compounds may have potential application in the design of fluorescent photochromic materials.     

地-气耦合动力系统的近似解析解

本文研究了一类地-气耦合系统的非线性模式.利用同伦映射方法，将问题转化为线性问题求解.最后得到了原非线性问题的近似表示式. 关键词： 非线性 地-气耦合 动力系统 同伦映射     

An Organodiselenide Comediator to Facilitate Sulfur Redox Kinetics in Lithium–Sulfur Batteries with Encapsulating Lithium Polysulfide Electrolyte

Lithium–sulfur (Li–S) batteries are regarded as promising high-energy-density energy storage devices. However, the cycling stability of Li–S batteries is restricted by the parasitic reactions between Li metal anodes and soluble lithium polysulfides (LiPSs). Encapsulating LiPS electrolyte (EPSE) can efficiently suppress the parasitic reactions but inevitably sacrifices the cathode sulfur redox kinetics. To address the above dilemma, a redox comediation strategy for EPSE is proposed to realize high-energy-density and long-cycling Li–S batteries. Concretely, dimethyl diselenide (DMDSe) is employed as an efficient redox comediator to facilitate the sulfur redox kinetics in Li–S batteries with EPSE. DMDSe enhances the liquid–liquid and liquid–solid conversion kinetics of LiPS in EPSE while maintains the ability to alleviate the anode parasitic reactions from LiPSs. Consequently, a Li–S pouch cell with a high energy density of 359 Wh kg⁻¹ at cell level and stable 37 cycles is realized. This work provides an effective redox comediation strategy for EPSE to simultaneously achieve high energy density and long cycling stability in Li–S batteries and inspires rational integration of multi-strategies for practical working batteries.     

MFI/BEA双沸石复合物的合成及其在甲烷选择性还原NOx中的应用

以合成的β沸石固液混合物作为ZSM-5沸石的部分原料制备了含有ZSM-5和β沸石的双相沸石复合物MFI/BEA。采用XRD,FTIR,吡啶红外,NH₃-TPD,TEM,SEM和氮吸附-脱附等对合成的材料进行了表征。结果表明后合成的ZSM-5沸石在β沸石内部孕育生长,MFI/BEA双沸石复合物中两相沸石的组成比例可以通过控制第二步晶化时间来进行有效调控;与单一的Co-ZSM-5或Co-β相比,通过离子交换法制备的Co-基复合催化剂Co-MFI/BEA在富氧条件下甲烷选择催化还原NO反应中具有高活性和高的稳定性,并且表现出较好的抗SO₂毒化性能和良好的可逆性。     

两个基于双咪唑基配体的Co(Ⅱ)/Cu(Ⅰ)配合物的合成、晶体结构及荧光性质

以Co(ClO4)2·6H2O/Cu(ClO4)2·6H2O、1,4-双(咪唑基-1-基)丁烷(bib)/1,4-双(咪唑基-1-基)苯(bix)和4,4-(1,3-苯基双(亚甲基氧基))二苯甲酸(H2pmda)为原料,在水热条件下反应,得到了2个配合物{[Co(bib)3](ClO4)2}n(1)和{[Cu3(bix)(4.5)](ClO4)3}n(2)(H2pmda未参与反应),对它们进行了元素分析、红外光谱、荧光光谱、单晶和粉末X射线衍射表征。配合物1属于三方晶系,R 空间群,a=b=1.39337(5)nm,c=1.74054(13)nm,V=2.9265(3)nm^3,Mr=828.59,Dc=1.410g·cm^-3,F(000)=1293,μ=0.639mm^-1,Z=3,R1=0.0611,wR2=0.1937(I>(2σ(I))。配合物2也属于三方晶系,P 空间群,a=b=2.33441(15)nm,c=0.71511(9)nm,V=3.3749(5)nm^3,Mr=1561.28,Dc=1.536g·cm^-3,F(000)=1602,μ=1.131mm^-1,Z=2,R1=0.0439,wR2=0.1090(I>(2σ(I))。单晶结构分析表明配合物1为含有36元环的二维网状结构,配合物2为含有84元环的二维网状结构,并通过氢键或π-π堆积使它们扩展成超分子结构。此外,还研究了2个配合物的荧光性质。     

一类扰动洛伦兹系统的解法

研究了一个大气物理中洛伦兹系统的求解问题.首先利用广义变分原理构造一组变分迭代,其次决定系统的初始近似,最后通过变分迭代方法得到了对应模型的各次近似解.广义变分迭代方法是一个解析方法,得到的解还能够继续进行解析运算. 关键词： 洛伦兹方程 变分原理 近似解     

一类非线性尘埃等离子体孤波解

研究了一类非线性尘埃等离子体孤波解. 首先构造一个变分迭代, 其次决定系统的初始近似, 最后通过变分迭代方法得到了对应模型的各次近似解. 关键词： 等离子体 变分迭代 近似解     

扰动厄尔尼诺/拉尼娜-南方涛动模型的解

厄尔尼诺/拉尼娜-南方涛动(ENSO)是一个包括在赤道太平洋中海-气交互作用的年际现象. 本文创建一个求解ENSO模型非线性方程的近似方法. 并在这基础上借助同伦映射方法研究了一类ENSO模型振子模型的近似解与精确解. 同时讨论了近似解的精度. 从得到的结果看出,同伦映射方法能够用于分析ENSO模型在赤道东太平洋中的SST异常和气-海振荡的温跃层深度异常.     

A simulation study on nanoscale holes generated by gold nanoparticles on negative lipid bilayers

Understanding the interactions of gold nanoparticles (AuNPs) with cellular compartments, especially cell membranes, is of fundamental importance in obtaining their control in biomedical applications. An effort is made in this paper to investigate the interactions of 2.2 nm core AuNPs with negative model bilayer membranes by coarse-grained (CG) molecular dynamics (MD) simulation. The CG model of lipid bilayer was taken from Marrink et al. ( J. Phys. Chem. B 2004, 108, 750-760 ), whereas the CG AuNPs model was developed on the basis of both atomistic MD simulations and experimental data. It was found that AuNPs functionalized with cationic ligands penetrated into the negative bilayer membranes and generated significant disruptions on bilayers. The lipids surrounding the nanoparticle were highly disordered and the bulk surface of the bilayer exhibits some defective areas. Most importantly, it is observed that a nanoscale hole can be formed and expanded spontaneously on the peripheral regions of the 20 × 20 nm bilayer. The expansion of the hole is on the time scale of hundreds of nanosceonds. The fully expanded hole had a radius of ～5.5 nm and could transport water molecules at a rate of up to ～1100 molecule/ns. However holes could not be formed on a larger bilayer (28 × 28 nm). The factors that can eliminate hole formation on the bilayer also include the decrease of cationic lignads on the AuNP, the reduction of negative lipids in the bilayer, the release of bilayer surface tension, the lowering of temperature, and the addition of a high concentration of salt. The results suggest that a hole can only be formed on living cell membranes under extreme conditions.