Electrospun Poly(acrylonitrile-co-acrylic acid) Nanofibrous Membranes for Catalase Immobilization:Effect of Porphyrin Filling on the Enzyme Activity

Porphyrin-filled nanofibrous membranes were facilely prepared by electrospinning of the mixtures of poly(acrylonitrile-co-acrylic acid)(PANCAA) and porphyrins. 5,10,15,20-Tetraphenylporphyrin(TPP) and its metal-loderivatives(ZnTPP and CuTPP) were studied as filling mediators for the immobilization of redox enzyme. Results indicate that the introduction of TPP, ZnTPP and CuTPP improves the retention activity of the immobilized catalase. Among these three porphyrins, the ZnTPP-filled PANCAA nanofibrous membra...     

一类具有时滞和阶段结构的捕食者-食饵系统的全局稳定性

研究一类具有时滞和捕食者、食饵均具有阶段结构的捕食模型的全局稳定性.首先通过分析特征方程,运用Hurwitz判定定理,讨论了该模型非负平衡点的局部稳定性,并得到了Hopf分支存在的充分条件;其次运用单调迭代方法和比较定理,讨论了该模型的非负平衡点的全局稳定性,从而得到了保证该生态系统永久持续生存与灭绝的充分条件.     

Molecular Imprinting Fibrous Membranes of Poly（ acrylonitrile-co-acrylic acid） Prepared by Electrospinning

Introduction Overthepastfewdecades,molecularimprinting hasbeendescribedasatechnologyforpreparing“mo leculardoors”whichcanbematchedto“template keys”.Ithasbeenfoundtobeasimpleandeffective approachtointroducespecificrecognitionsitesintosyn theticpolymers…     

Preservation of equilibria for symplectic methods applied to Hamiltonian systems

In this paper, the linear stability of symplectic methods for Hamiltonian systems is studied. In par- ticular, three classes of symplectic methods are considered： symplectic Runge-Kutta （SRK） methods, symplectic partitioned Runge-Kutta （SPRK） methods and the composition methods based on SRK or SPRK methods. It is shown that the SRK methods and their compositions preserve the ellipticity of equilibrium points uncondi- tionally, whereas the SPRK methods and their compositions have some restrictions on the time-step.     

一类具有时滞的捕食模型的稳定性和Hopf分支

研究一类具有时滞和Beddington-DeAngelis功能性反应的捕食模型的稳定性和Hopf分支.以滞量为参数,得到了系统正平衡点的稳定性和Hopf分支存在的充分条件.应用一般泛函微分方程的度理论,研究了该系统的全局Hopf分支的存在性.     

一类具有时滞和Holling Ⅲ型功能性反应的捕食模型的稳定性和Hopf分支

研究一类具有时滞和Holling Ⅲ型功能性反应的捕食模型的稳定性和Hopf分支.以滞量为参数,得到了系统正平衡点的稳定性和Hopf分支存在的充分条件,给出了确定Hopf分支方向和分支周期解的稳定性的计算公式.     

INTERACTION BETWEEN THE SURFACE GLYCOSYLATED POLYPROPYLENE MEMBRANE AND LECTIN

A glycopolymer bearing glucose residues was tethered onto the surface of polypropylene microporous membrane by UV-induced graft polymerization ofα-allyl glucoside.Concanavalin A (Con A),a glucose recognizing lectin,could be specifically adsorbed to the membrane surface.On the other hand,the membrane surface showed no recognition ability to another lectin peanut agglutinin.Moreover,the recognition complex between the glycosylated membrane surface and Con A could be inhibited by glucose and mannose solutio...     

Syntheses and Surface Properties of Polyacrylonitrile-based Copolymer Membranes Containing Sugar Moieties

Introduction Asatypeofwidelyusedmembranematerials, polyacrylonitrile(PAN)hasbeeninvestigatedby manyresearchersinthefieldsofpervaporation,ul- trafiltration,anddialysis[1_4].However,PAN- basedmembranesarerelativelyhydrophobicwitha lowbiocompatibility.Thesepropertieslimittheir furtherapplicationsinaqueoussolutionseparation andtheirusageasbiomedicaldevices.Muchatten- tionhasbeenpaidtoimprovingthecharacteristics ofPAN-basedmembranes.Thecopolymerization ofANwithhydrophilicmonomersisconsideredas…     

Structure-Preserving Algorithms for a Class of Dynamical Systems

In this paper,we study structure-preserving algorithms for dynamical systems defined by ordinarydifferential equations in R~n.The equations are assumed to be of the form y~·=A(y) D(y) R(y),where A(y)is the conservative part subject to     

一类捕食者-食饵模型的稳定性及Hopf分支

研究一类具有时滞和阶段结构的捕食模型的稳定性和Hopf分支.以滞量为参数,得到了系统正平衡点的稳定性和Hopf分支存在的充分条件.利用规范型和中心流形定理,给出了确定Hopf分支方向和分支周期解的稳定性的计算公式.