亲水性含环氧基磁性聚合物微球的制备与性能表征

选择甲酰胺作磁性Fe3O4微晶的分散剂,通过设计反相悬浮聚合体系,合成了粒径分布窄、球状亲水性含环氧基磁性聚合物(MGM).利用扫描电子显微镜(SEM)、红外光谱(FT-IR)、X射线粉末衍射仪(XRD)、振动样品磁强计(VSM)和低温N2吸附以及化学分析方法对聚合物进行了性能表征.结果表明,合成的MGM呈球形,且粒度分布较窄,粒径为0.13~0.28 mm的粒子占91%;甲酰胺分散Fe3O4,微晶表面的亲水性进一步增强,单体甲基丙烯酸缩水甘油酯和N,N′-亚甲基双丙烯酰胺交联共聚生成的胶粒能够包埋Fe3O4微晶形成胶核,胶核聚集形成均匀、稳定的MGM微球.MGM中Fe3O4含量为6.17%时,比饱和磁化强度σs达6.5 emu/g;其比表面积、平均孔径和孔容分别为117.6 m2/g,15.6 nm和0.46 cm3/g,表面环氧基团含量为0.53 mmol/g.MGM借助自身的活性环氧基团在十分温和的条件下共价偶联青霉素酰化酶(penicillin G acylase EC 3.5.1.11,简称PGA),制备的固定化酶在37℃下催化水解青霉素G钾生成6-氨基青霉烷酸(6-APA)的表观活性达502IU/g,并且在使用过程中没有出现磁聚集现象.     

An error-free algorithm to solve a linear system of polynomial equations

The paper presents an error-free algorithm to solve a system of linear equations with polynomial coefficients. Modular arithmetic in residual polynomial class and in residual numeric class is employed. The algorithm is iterative and well suited for implementation for computers with vector operations and fast and error-free convolutors.     

Inverse Scattering Problem for the Schrödinger Operator with External Yang–Mills Potentials in Two Dimensions at Fixed Energy

ABSTRACT

We consider the Schrödinger equation in ?², with external Yang–Mills potentials that decay exponentially as |x| → ∞. We prove that the scattering amplitude at fixed positive energy determines the potentials uniquely modulo a gauge transformation, assuming that potentials are small.     

A Branch-and-price Algorithm for the Multi-Vehicle Covering Tour Problem

In this paper, we propose a Branch-and-price (BP) algorithm and a Column Generation Heuristic (CGH) for the Multi-Vehicle Covering Tour Problem (m-CTP). Specific dominance and extension pruning rules are introduced to accelerate the resolution of the pricing problems. To the best of our knowledge, this is the first work dedicated to the exact resolution of m-CTP. The algorithm managed to solve about 30% of the instances in our test bed, within a 4 hour CPU time limit. Our preliminary computational experiments suggest that both the lower bounds provided by the formulation behind BP and the CGH upper bounds are of good quality.     

Inverse optimization for linearly constrained convex separable programming problems

In this paper, we study inverse optimization for linearly constrained convex separable programming problems that have wide applications in industrial and managerial areas. For a given feasible point of a convex separable program, the inverse optimization is to determine whether the feasible point can be made optimal by adjusting the parameter values in the problem, and when the answer is positive, find the parameter values that have the smallest adjustments. A sufficient and necessary condition is given for a feasible point to be able to become optimal by adjusting parameter values. Inverse optimization formulations are presented with ℓ₁ and ℓ₂ norms. These inverse optimization problems are either linear programming when ℓ₁ norm is used in the formulation, or convex quadratic separable programming when ℓ₂ norm is used.     

Research Problems from the BCC21

A collection of open problems, mostly presented at the problem session of the 21st British Combinatorial Conference.     

模糊逻辑在机器人逆运动学求解中的应用

冗余机器人逆运动学求解的方法很多，多数都不能很好的满足实时控制的要求，本文运用模糊逻辑的思想，构造了一种逆运动学求解方法，其计算量较其它方法大大减小，且满足实时控制的要求，仿真结果也证明了该方法的可行性。     

Inverse Problem for a Class of Two-Dimensional Diffusion Equations with Piecewise Constant Coefficients

In this paper, we consider an inverse problem for a class of two-dimensional diffusion equations with piecewise constant coefficients. This problem is studied using an explicit formula for the relevant spectral measures and an asymptotic expansion of the solution of the diffusion equations. A numerical method that reduces the inverse problem to a sequence of nonlinear least-square problems is proposed and tested on synthetic data.     

Inverse gas chromatography in the study of polymer degradation. Part 4: A study of model systems for reinforced vulcanizates

Summary Inverse gas chromatography with olefinic stationary phases, impregnated with silica gel or carbon black, and air as carrier gas has been found to yield characteristic shifts of retention data and concomitant changes in peak shape. The plots of retention index versus oxygen flow obtained indicate carbon black to have significant antioxidant properties, which are not altogether lost on solvent extraction. On the other hand, silica gel yields results consistence with the existence of a novel chain scission repair process.