细胞色素b5突变体V45H NMR初步研究

通过分析在H2O和D2O中采集,DQF-COSY,TOCSY和NOESY等二维核磁共振波谱鉴定了细胞色素b5定点突变体V45H(残基Val^45突变为His^45)的大多数氨基酸残基的质子自旋系统,通过解析NOESY谱中的dNN(i,i+1),dαN(i,i+1),dαN(i,i+2),dαN(i,i+3),dαβ(i,i+3)和dβN(i,i+1)等NOE相关,完成了其序列特异性归属以及主链和侧链质子共振信号的全归属。突变体V45H的二级结构分析表明残基Val^45突变为His^45对分子的整体折叠影响不大。但是,与野生型细胞色素b5相比较,突变体V45H主链酰胺质子的化学位移指数提示突变使其血红素疏水腔的微环境受到扰动。以上实验结果为进一步测定V45H的溶液结构和分析残基Val^45在蛋白质中的作用提供了基础。     

45钢柱壳膨胀断裂的应变率效应

采用前照明高速分幅照相技术拍摄到在爆轰加载下45钢柱壳表面裂纹生成、扩展及产物泄漏过程的清晰图像,较准确地测量了膨胀断裂的时间与应变。 45钢柱壳在炸药爆轰加载下,断裂应变随应变率的增加而增加,当应变率达到一定值,断裂应变随应变率的增加而降低,出现了动态断裂中的塑性峰现象。     

On the flow of chemically reacting gaseous mixture

We consider the Cauchy problem for the system of equations governing flow of isothermal reactive mixture of compressible gases. Our main contribution is to prove sequential stability of weak solutions when the state equation essentially depends on the species concentration and the viscosity coefficients vanish on vacuum. Moreover, under additional assumption on the “cold” component of the pressure in the regions of small density, we prove the existence of weak solutions for arbitrary large initial data.     

The minimal degree of plane models of double covers of smooth curves

If X is a smooth curve such that the minimal degree of its plane models is not too small compared with its genus, then X has been known to be a double cover of another smooth curve Y under some mild condition on the genera. However there are no results yet for the minimal degrees of plane models of double covers except some special cases. In this paper, we give upper and lower bounds for the minimal degree of plane models of the double cover X in terms of the gonality of the base curve Y and the genera of X and Y. In particular, the upper bound equals to the lower bound in case Y is hyperelliptic. We give an example of a double cover which has plane models of degree equal to the lower bound.     

Weighted differentiation composition operator from logarithmic Bloch spaces to Bloch‐type spaces

In this paper, we give a new characterization for the boundedness of weighted differentiation composition operator from logarithmic Bloch spaces to Bloch‐type spaces and calculate its essential norm in terms of the n‐th power of induced analytic self‐map on the unit disk. From which a sufficient and necessary condition of compactness of this operator follows immediately.     

Fractal differential equations on the Sierpinski gasket

Let denote the symmetric Laplacian on the Sierpinski gasket SG defined by Kigami [11] as a renormalized limit of graph Laplacians on the sequence of pregaskets G_m whose limit is SG. We study the analogs of some of the classical partial differential equations with playing the role of the usual Laplacian. For harmonic functions, biharmonic functions, and Dirichlet eigenfunctions of , we give efficient algorithms to compute the solutions exactly, we display the results of implementing these algorithms, and we prove various properties of the solutions that are suggested by the data. Completing the work of Fukushima and Shima [8] who computed the Dirichlet eigenvalues and their multiplicities, we show how to construct a basis (but not orthonormal) for the eigenspaces, so that we have the analog of Fourier sine series on the unit interval. We also show that certain eigenfunctions have the property that they are a nonzero constant along certain lines contained in SG. For the analogs of the heat and wave equation, we give algorithms for approximating the solution, and display the results of implementing these algorithms. We give strong evidence that the analog of finite propagation for the wave equation does not hold because of inconsistent scaling behavior in space and time.Research supported in part by the National Science Foundation, Grant DMS-9623250.Research supported by the National Science Foundation through the Research Experiences for Undergraduates (REU) Program.     

Potential theory of hyperfinite Dirichlet forms

In this paper, we are going to study the capacity theory and exceptionality of hyperfinite Dirichlet forms. We shall introduce positive measures of hyperfinite energy integrals and associated theory. Fukushima's decomposition theorem will be established on the basis of discussing hyperfinite additive functionals and hyperfinite measures. We shall study the properties of internal multiplicative functionals, subordinate semigroups and subprocesses. Moreover, we shall discuss transformation of hyperfinite Dirichlet forms.Research was supported by the National Natural Science Foundation of P.R. China, No. 18901004. The support from the position of Wissenschaftliche Hilfskraft of Ruhr-University Bochum under Prof. Sergio Albeverio is also acknowledged.     

One-dimensional perturbations of the shift

The structure of isometries on a Hilbert space are well studied. In this paper we study contractions which are one-dimensional perturbations of isometries, in particular, perturbations of the shift operator onH ².     

Algebraic points of low degree¶on the Fermat curve of degree seven

We determine all algebraic points of degree at most five over Q on the Fermat curve of degree seven. Received: 26 February 1998 / Revised version: 1 June 1998     

Two-dimensional convexities are join-hull commutative

It is shown that two-dimensional convex structures with certain natural properties are join-hull commutative. The main intermediate step is the computation of the so-called exchange number. We also give two examples of three-dimensional convexities which are not join-hull commutative. The second one has certain additional properties showing that the main theorem is sharp in many other respects. These properties are obtained from a study of convex hyperspaces.