一种吲哚螺吡咯多取代杂环化合物的合成及其晶体结构

利用多组分1,3偶极环加成反应方法,合成了一种新的螺环结构1'-甲基-3'-吡啶甲酰基-4'-(2-噻吩基)螺[吲哚啉-3,2'-吡咯啉]-2-酮化合物,并对该化合物进行了红外光谱、核磁共振谱及X-射线单晶衍射表征.单晶衍射结果表明:该晶体属于三斜晶系,空间群为P-1,晶体参数为a=0.899 9(1)nm,b=0.914 4(1)nm,c=1.271 1(2)nm,α=92.852(1)°,β=107.305(2)°,γ=101.580(1)°.在分子晶体结构中,吡咯啉环采用了信封式构象,通过螺碳原子与吲哚啉环相连,形成刚性螺环结构,2个环接近垂直构型,其二面角为84.15(2)°.     

过渡元素掺杂Fe_3O_4(001)表面磁电性能的理论研究

采用基于密度泛函理论的第一性原理方法,计算Fe_3O_4,Fe_3O_4(001)表面以及过渡元素掺杂表面的电子结构和磁性。结果表明Fe_3O_4的半金属性主要来源于B位Fe离子,并且Fe的3d轨道发生强烈自旋极化;比较(001)表面不同终端A和B终端的表面能和电子结构,得出两种终端稳定性存在差异且A终端较稳定同时表现半金属性;由过渡元素V、Cr、Mn、Co、Cu和Zn取代Fe_3O_4(001)表面A终端A位Fe进行掺杂,形成的6种新表面结构都保持了半金属性。对比它们的表面能和磁矩,Mn掺杂的表面结构最稳定并且磁矩明显增大。     

Antibacterial membranes based on chitosan and quaternary ammonium salts modified nanocrystalline cellulose

Etherification of nanocrystalline cellulose (NCC) with three kinds of quaternary ammonium salts epoxypropyltrimethylammonium chloride, N,N‐dimethyl‐N‐dodecyl‐N‐(1,2‐epoxypropyl) ammonium chloride (DMDEPAC), and N,N‐dimethyl‐N‐octadecyl‐N‐(1,2‐epoxypropyl) ammonium chloride (DMOEPAC) was successfully performed via a nucleophilic addition reaction. The synthesized DMDEPAC and DMOEPAC were characterized by nuclear magnetic resonance. The modified NCC particles, NCC epoxypropyltrimethylammonium chloride, NCC‐DMDEPAC, and NCC‐DMOEPAC, were characterized by energy dispersive spectrometer. Nanocomposite films based on chitosan (CS) containing quaternary ammonium salts modified NCC were prepared with nanoparticle loadings of 5.0, 7.5, and 10.0%, respectively. The effect of nanoparticle content on the tensile strength of composite films was studied. The results indicated that the films with 5.0% nanoparticle loading exhibited the biggest increase in tensile strength. Surface morphology, smoothness, and antibacterial properties of composite films containing 5% modified NCC were also studied. CS/NCC‐DMDEPAC‐5.0 and CS/NCC‐DMOEPAC‐5.0 displayed excellent biocidal abilities against both Gram‐positive Staphylococcus aureus (ATCC 6538) and Gram‐negative Escherichia coli O157:H7 (ATCC 43895). The bio‐based nanocomposite films with increased mechanical strength and excellent antibacterial properties show great potential as food packaging materials. Copyright © 2017 John Wiley & Sons, Ltd.     

Modified classification of non-self-adjoint second-order difference equations

This paper is concerned with the classification of non-self-adjoint second-order difference equations. The relationship between the number of summable solutions of non-self-adjoint difference equations and that of the discrete linear Hamiltonian system is discussed. A classification for non-self-adjoint second-order difference equations is established, which is independent of the choice of the rotated half plane and the fixed point.     

Rigidity Theorems for Complete Sasakian Manifolds with Constant Pseudo-Hermitian Scalar Curvature

The orthogonal decomposition of the Webster curvature provides us a way to characterize some canonical metrics on a pseudo-Hermitian manifold. We derive some subelliptic differential inequalities from the Weitzenböck formulas for the traceless pseudo-Hermitian Ricci tensor of Sasakian manifolds with constant pseudo-Hermitian scalar curvature and the Chern–Moser tensor of the Sasakian pseudo-Einstein manifolds, respectively. By means of either subelliptic estimates or maximum principle, some rigidity theorems are established to characterize Sasakian pseudo-Einstein manifolds among Sasakian manifolds with constant pseudo-Hermitian scalar curvature and Sasakian space forms among Sasakian pseudo-Einstein manifolds, respectively.     

光触发自修复聚合物研究进展

近几年,由于光触发自修复聚合物具有可控快速等优势,其在自修复聚合物领域中占据了重要的地位。光触发自修复聚合物实现自修复的方法主要分为3类,分别是基于光交联反应的自修复、基于光触发交换反应的自修复和基于光热效应的自修复。本文主要从光触发自修复聚合物的修复机制以及修复过程中涉及的化学本质两个方面,重点阐述了上述3类光触发自修复方法的最新研究进展,强调3种光触发自修复之间的联系和共同点。同时,对光触发自修复聚合物未来的发展前景进行了展望。     

The p-th moment stability of solutions to impulsive stochastic differential equations driven by G-Brownian motion

In this paper, we consider a class of impulsive stochastic differential equations driven by G-Brownian motion (IGSDEs in short). By means of the G-Lyapunov function method, some criteria on p-th moment stability and p-th moment asymptotical stability for the trivial solutions of IGSDEs are established. An example is presented to illustrate the efficiency of the obtained results.     

Existence of multiplicity harmonic and subharmonic solutions for second‐order quasilinear equation via Poincaré‐Birkhoff twist theorem

In this paper, we investigate the existence and multiplicity of harmonic and subharmonic solutions for second‐order quasilinear equation where , g satisfies the superlinear condition at infinity. We prove that the given equation possesses harmonic and subharmonic solutions by using the phase‐plane analysis methods and a generalized version of the Poincaré‐Birkhoff twist theorem.     

Equality of the homogeneous and the Gabor wave front set

We prove that Hörmander’s global wave front set and Nakamura’s homogeneous wave front set of a tempered distribution coincide. In addition, we construct a tempered distribution with a given wave front set, and we develop a pseudodifferential calculus adapted to Nakamura’s homogeneous wave front set.