由4-羟基苯甲醛合成香兰素的CNDO/2研究

用CNDO/2法研究了从4-羟基苯甲醛合成香兰素的化学反应,并作了理论解析。结果表明,合成路线是可行的,总收率为85%。     

Global dynamics of SIS models with transport-related infection

To understand the effect of transport-related infection on disease spread, an epidemic model for several regions which are connected by transportation of individuals has been proposed by Cui, Takeuchi and Saito [J. Cui, Y. Takeuchi, Y. Saito, Spreading disease with transport-related infection, J. Theoret. Biol. 239 (2006) 376-390]. Transportation among regions is one of the main factors which affects the outbreak of diseases. The purpose of this paper is the further study of the local asymptotic stability of the endemic equilibrium and the global dynamics of the system. Sufficient conditions are established for global asymptotic stability of the endemic equilibrium. Permanence is also discussed. It is shown that the disease is endemic in the sense of permanence if and only if the endemic equilibrium exists. This implies that transport-related infection on disease can make the disease endemic even if all the isolated regions are disease free.     

A modified Leslie–Gower predator–prey model with prey infection

The disease effect on ecological systems is an important issue from mathematical and experimental point of view. In this paper, we formulate and analyze a predator–prey model for the susceptible population, infected population and their predator population with modified Leslie–Gower (or Holling–Tanner) functional response. Mathematical analysis of the model equations with regard to invariance of nonnegativity and boundedness of solutions, local and global stability of the biological feasible equilibria and permanence of the system are presented. When the rate of infection crosses a critical value, we determine that the strictly positive interior equilibrium undergoes Hopf bifurcation. From our numerical simulations, we observe that the predation rate also plays an important role on the dynamic behavior of our system.     

Global stability in Gilpin-Ayala competitive model with time delays

1.IntroductionOneofthesimplestmodelsofthedynamicofn-interactingspecieshasbeenproposedbyVolterra(1931)[4]intheformofanautonomoussytemofnordinarydifferentialequationswithquadraticnonlinearities,~Iwhereb.,a.,(i,j~l,2..-n)areconstantsandxi(t)denotesthepopulationsizeorbiomassofithspeciesattimet.Basedonalargenumberofexperimentalresults,GilpinandAyala[3]proposedaslightlymoregeneralcompetitionsystemWherer,,k,,6.-,a,,(i.j~l,2...'.n)areconstants.System(1.2)isgeneralandhavetheLotka--Volterrasystem(1.I…     

Kinetic versus thermodynamic access to imidazoisoindolones, benzimidazoisoindolones, and [1,4]diazepinoisoindolones: intramolecular nitrogen and π-aromatic trapping of N-acyliminium cation

Efficient assembly of substituted imidazo[2,1-a]isoindolones I is reported from suitable α,β-diamine IV (or corresponding β-nitroamine) and phthalic anhydride (1) in a three- or four-step sequence in good yields. The key step of this methodology is based on an intramolecular α-aza-amidoalkylation of the N-acyliminium species. Furthermore, when R₂ is an aromatic moiety a competing α-amidoalkylation took place and imidazo[2,1-a]isoindolones (or benzimidazo[2,1-a]isoindolones) I and/or isoindolo[1,4]benzodiazepines III were obtained under kinetic or thermodynamic control. The chemoselectivity of these transformations is also discussed.     

Stability and backward bifurcation on a cholera epidemic model with saturated recovery rate

In this paper, a cholera epidemic model with saturated recovery rate is studied. Backward bifurcation leading to bistability possibly occurs, and global dynamics are shown by compound matrices and geometric approaches. Numerical simulations are presented to illustrate the results. Our results suggest that the basic reproduction number itself is not enough to describe whether cholera will prevail or not when the resources for treatment of infectives are limited and suggest that we should pay more attention to the initial state of cholera. Copyright © 2016 John Wiley & Sons, Ltd.     

60-nt DNA Direct Detection without Pretreatment by Surface-Enhanced Raman Scattering with Polycationic Modified Ag Microcrystal Derived from AgCl Cube

Direct detection of long-strand DNA by surface-enhanced Raman scattering (SERS) is a valuable method for diagnosis of hereditary diseases, but it is currently limited to less than 25-nt DNA strand in pure water, which makes this approach unsuitable for many real-life applications. Here, we report a 60-nt DNA label-free detection strategy without pretreatment by SERS with polyquaternium-modified Ag microcrystals derived from an AgCl cube. Through the reduction-induced decomposition, the size of the about 3 × 3 × 3 μm³ AgCl cube is reduced to Ag, and the surface is distributed with the uniform size of 63 nm silver nanoparticles, providing a large area of a robust and highly electromagnetic enhancement region. The modified polycationic molecule enhances the non-specific electrostatic interaction with the phosphate group, thereby anchoring DNA strands firmly to the SERS enhanced region intactly. As a result, the single-base recognition ability of this strategy reaches 60-nt and is successfully applied to detect thalassemia-related mutation genes.     

碱催化合成N-羟甲基丙烯酰胺的动力学

N-羟甲基丙烯酰胺(N-MAM)具有可聚合的双键和可缩合的羟基,能进一步与其它烯烃化合物反应生成共聚物及交联产物,是一种有重要经济价值的水溶性功能高分子单体。     

Delay induced stability switches in a viral dynamical model

In this paper, a delay-differential mathematical model that described HIV infection of CD4⁺ T cells is analyzed. The effect of time delay on stability of the equilibria of the infection model has been studied. And the sufficient criteria for stability switch of the infected equilibrium and the local and global asymptotic stability of the uninfected equilibrium are given. By using the geometric stability switch criterion in the delay-differential system with delay-dependent parameters, we present that stable equilibria become unstable as the time delay increases. Numerical simulations are carried out to explain the mathematical conclusions.

     

纳米抗菌剂的研究进展

纳米抗菌剂是一种新型高效的抗菌药物,现已逐步应用于纺织、建筑、医疗等各个行业中。传统抗菌方法存在着安全性差、灭菌时间长、操作不方便等缺点,纳米抗菌剂具有使用安全、方便,稳定性好,抗菌谱广和抗菌效力强等优点。综述了纳米抗菌剂的发展概况,展望了纳米抗菌剂发展的主要趋势。