Resonance phenomena and long-term chaotic advection in volume-preserving systems

Creating chaotic advection is the most efficient strategy to achieve mixing on microscale or in very viscous fluids. In this paper, we present a quantitative theory of the long-time resonant mixing in 3D near-integrable flows. We use the flow between two coaxial elliptic counter-rotating cylinders as a demonstrative model, where multiple scatterings on resonance result in mixing by causing the jumps of adiabatic invariants. We improve the existing estimates of the width of the mixing domain. We show that the resulting mixing both on short and long time scales can be described in terms of a single diffusion-type equation with a diffusion coefficient depending on the averaged effect of multiple passages through resonances. We discuss the exact location of the boundaries of the chaotic domain and show how it affects the properties of mixing.     

饲用纤维素酶活力测定方法的改进

探讨和分析了影响3，5-二硝基水杨酸（DNS）法测定饲用纤维索酶活力的几个因素．研究表明，测定条件对测定结果影响较大，因此进行纤维索酶活力测定时．必需规定测试条件．通过对饲用纤维索酶的实验表明：在40℃，pH4．8．反应时间30min，底物为0．8％羧甲基纤维索钠（CMC—Na）以DNS法测定酶活较为合适，同时待测酶液的浸提时间为室温下1h，空白对照样的酶液灭活时间应大于15min．