碱性品红分子在纳米磷化镓粒子表面的吸附取向(英文)

利用表面增强拉曼光谱,初步确定了吸附于纳米磷化镓(GaP)粉体表面的碱性品红分子的取向。在295K时,将50 mg GaP粉体分别置于50 ml,4.7×10-3M和50 ml,4.74×10-6M碱性品红水溶液中。对由较高浓度溶液形成的吸附系统持续搅拌24小时;而对极稀溶液吸附系统则连续搅拌处理7天。在经过过滤、干燥处理后,吸附有染料分子的GaP粉体被直接用于碱性品红的表面拉曼光谱测试。通过对染料分子中央碳原子呼吸振动和氮-苯环伸缩振动模式的相对强度进行分析可知:在较高浓度的溶液中,染料分子主要以一种混合取向方式吸附于GaP粉体表面上,即“端基接触”和“平躺”两种方式;而在极稀溶液中,染料分子则仅以“端基接触”方式吸附于GaP粉体表面上。     

Numerical study of the basic stationary spherical couette flows at low Reynolds numbers

Previously developed iterative numerical methods with splitting of boundary conditions intended for solving an axisymmetric Dirichlet boundary value problem for the stationary Navier-Stokes system in spherical layers are used to study the basic spherical Couette flows (SCFs) of a viscous incompressible fluid in a wide range of outer-to-inner radius ratios R/r (1.1 ≤ R/r ≤ 100) and to classify such SCFs. An important balance regime is found in the case of counter-rotating boundary spheres. The methods converge at low Reynolds numbers (Re), but a comparison with experimental data for SCFs in thin spherical layers show that they converge for Re sufficiently close to Re_cr. The methods are second-order accurate in the max norm for both velocity and pressure and exhibit high convergence rates when applied to boundary value problems for Stokes systems arising at simple iterations with respect to nonlinearity. Numerical experiments show that the Richardson extrapolation procedure, combined with the methods as applied to solve the nonlinear problem, improves the accuracy up to the fourth and third orders for the stream function and velocity, respectively, while, for the pressure, the accuracy remains of the second order but the error is nevertheless noticeably reduced. This property is used to construct reliable patterns of stream-function level curves for large values of R/r. The possible configurations of fluid-particle trajectories are also discussed.     

运输问题的退化解及表解中0元的添加

在运输问题表上作业法中,有时会遇到退化解问题,这样在给调运方案时需要在调运表上添加0元,可是0应添在何处?大多数文献中均未具体给出或给出的结论有误,0元的添加不当有时会导致一系列问题出现,本文将讨论这些问题,且给出一个0元添加的确定的答案.     

A factorization method for q-Racah polynomials

We develop a factorization method for q-Racah polynomials. It is inspired by the approach to q-Hahn polynomials based on the q-Johnson scheme, but we do not use association scheme theory nor Gel'fand pairs but only manipulation of q-difference operators.     

Proof of Andrews' conjecture on a 4φ3 summation

We give a new proof of a ₄φ₃ summation due to G.E. Andrews and confirm another ₄φ₃ summation conjectured by him recently. Some variations of these two ₄φ₃ summations are also given.     

Generating functions for vector partition functions and a basic recurrence relation

ABSTRACT

We define a generalized vector partition function and derive an identity for the generating series of such functions associated with solutions to basic recurrence relations of combinatorial analysis. As a consequence we obtain the generating function of the number of generalized lattice paths and a new version of the Chaundy-Bullard identity for the vector partition function.     

Mg-Sn-Si系合金的热力学基础及合金相演变过程分析

研究了Mg-Sn-Si系合金的热力学基础及合金相的演变过程. 结果表明: 对于Mg-Sn-Si系合金, 合金相的比热容随着温度增加而增加, 在低温下变化迅速, 而在高温下变化平缓, 其热膨胀系数在低温范围内随温度升高呈指数形式增加, 而在高温范围内呈线性增大. 在Mg₂ (Si_x, Sn_1-x)、Mg₂ (Sn_x, Si_1-x)相结构中, Sn(Si)原子的取代位置不固定, 可以是面心, 也可以是顶点. 常规凝固过程中, 由于处于非平衡状态, x的取值范围有所波动, 对于Mg₂ (Si_x, Sn_1-x)和Mg₂ (Sn_x, Si_1-x) 两种结构, x的取值范围在0.25或0.75附近. Mg₂ (Si, Sn)的生成温度较高, 可从液相中直接析出, 也可由Mg₂Si转化而来, 而Mg₂ (Sn, Si)的生成温度较低, 只能从基体中析出, 随着Sn含量的增加, 开始析出Mg₂ (Sn, Si)相的温度升高.     

一个含四个独立基的变换公式及其应用

本文利用反演的方法得到了一个四个独立基的变换公式并由此得到了几个新的基本超几何级数求和公式和超几何级数求和公式.     

具有隐性传染的手足口病模型分析

建立并分析了一个带有隐性传染的手足口病模型,计算了基本再生数.构造适当的Lyapunov函数证明了无病平衡点的稳定性,分析了当R_0>1时疾病的一致持续性,并进一步证明了正平衡点的存在性.