Synthesis,Characterizations, and Crystal Structures of α-Hydroxyphosphonic Acid Esters

This article describes the synthesis of α-hydroxyphosphonic acid esters using the Pudovik reaction. IR, ¹H NMR, ¹³C NMR, ³¹P NMR, MS, and elemental analysis were employed to confirm their structures. X-ray structure analysis is reported for six compounds. The antibacterial activities of these compounds are also reported.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

光学相干控制中脉冲光束等相面的实时测控

描述了飞秒脉冲基频光、倍频光光束位相差对相干控制光电流注入的控制作用,提出一种控制基频光、倍频光在全光孔径干涉光场内的等相面保持一致的实验方案,制作了一套相位差稳定自动控制系统,并应用于光学相干控制光电流实验中,获得较好的实时控制结果.     

Numerical methods for computing ground states and dynamics of nonlinear relativistic Hartree equation for boson stars

Efficient and accurate numerical methods are presented for computing ground states and dynamics of the three-dimensional (3D) nonlinear relativistic Hartree equation both without and with an external potential. This equation was derived recently for describing the mean field dynamics of boson stars. In its numerics, due to the appearance of pseudodifferential operator which is defined in phase space via symbol, spectral method is more suitable for the discretization in space than other numerical methods such as finite difference method, etc. For computing ground states, a backward Euler sine pseudospectral (BESP) method is proposed based on a gradient flow with discrete normalization; and respectively, for computing dynamics, a time-splitting sine pseudospectral (TSSP) method is presented based on a splitting technique to decouple the nonlinearity. Both BESP and TSSP are efficient in computation via discrete sine transform, and are of spectral accuracy in spatial discretization. TSSP is of second-order accuracy in temporal discretization and conserves the normalization in discretized level. In addition, when the external potential and initial data for dynamics are spherically symmetric, the original 3D problem collapses to a quasi-1D problem, for which both BESP and TSSP methods are extended successfully with a proper change of variables. Finally, extensive numerical results are reported to demonstrate the spectral accuracy of the methods and to show very interesting and complicated phenomena in the mean field dynamics of boson stars.     

A structure-preserving finite element approximation of surface diffusion for curve networks and surface clusters

We consider the evolution of curve networks in two dimensions (2d) and surface clusters in three dimensions (3d). The motion of the interfaces is described by surface diffusion, with boundary conditions at the triple junction points lines, where three interfaces meet, and at the boundary points lines, where an interface meets a fixed planar boundary. We propose a parametric finite element method based on a suitable variational formulation. The constructed method is semi-implicit and can be shown to satisfy the volume conservation of each enclosed bubble and the unconditional energy-stability, thus preserving the two fundamental geometric structures of the flow. Besides, the method has very good properties with respect to the distribution of mesh points, thus no mesh smoothing or regularization technique is required. A generalization of the introduced scheme to the case of anisotropic surface energies and non-neutral external boundaries is also considered. Numerical results are presented for the evolution of two-dimensional curve networks and three-dimensional surface clusters in the cases of both isotropic and anisotropic surface energies.     

海藻糖标准样品的研制

研制了海藻糖国家标准样品。以食品级海藻糖粗品为原料,纯化制备海藻糖,采用红外光谱(IR)、质谱和核磁共振谱(NMR)以及单晶衍射等方法进行结构确证。样品分装成400瓶后,采用离子色谱法进行均匀性、稳定性检验和定值分析。从样品中随机抽取15瓶进行均匀性检验,经F检验表明,在95%的置信区间范围内,样品均匀性良好。在40℃下,经过24个月稳定性考察,结果表明样品稳定性良好。标准样品经国内8家具有分析资质的实验室进行协同定值,并评定了定值结果的不确定度,海藻糖标准样品定值结果为99.72%,扩展不确定度为0.26%(k=1.96)。该标准样品达到国家标准样品的技术要求,可用于有关海藻糖的方法校正和质量控制。     

一种多用途的光电自动微调器

本文介绍一种多用途光电自动微调器,它是由单片微机控制的具有自动反馈功能的光电子器件,适用于各种利用微调方式对光路进行实时自动反馈式平衡准直和精密测量.     

Error estimates for the finite element approximation of linear elastic equations in an unbounded domain

In this paper we present error estimates for the finite element approximation of linear elastic equations in an unbounded domain. The finite element approximation is formulated on a bounded computational domain using a nonlocal approximate artificial boundary condition or a local one. In fact there are a family of nonlocal approximate boundary conditions with increasing accuracy (and computational cost) and a family of local ones for a given artificial boundary. Our error estimates show how the errors of the finite element approximations depend on the mesh size, the terms used in the approximate artificial boundary condition, and the location of the artificial boundary. A numerical example for Navier equations outside a circle in the plane is presented. Numerical results demonstrate the performance of our error estimates.

     

偶氮侧基聚合物光致异构动力学研究

本文对偶氮侧基聚合物相位共轭光时间特性进行了研究,得到了相位共扼光产生机制─光致异构过程的时间常数.在相位共轭光上升阶段,其时间常数在0.4～0.5s之间,在相让共轭光的衰减过程,衰减满足双指数关系,分段拟合得到较好的结果,且得到快过程的时间常数为0.27s,慢过程的时间常数为0.78s.     

GaN薄膜的蓝光和红光发射机理研究

由于生长工艺的不完善，非掺杂GaN薄膜中通常存在未知的杂质和缺陷，产生与这些未知杂质和缺陷能级相关的发光。报道了非掺杂GaN薄膜的692nm红色发光．并研究了非掺杂GaN薄膜的蓝、红色发光的发射机理；利用作者提出的吸收归一化光致发光激发光谱，直接测量出了非掺杂GaN薄膜的蓝、红色发光的初始态能级，确定蓝色发光为施主-价带跃迁复合，而红色发光为施主-受主跃迁复合；给出了黄、蓝、红光的发射模型。所取得的结果对于确定未知杂质和缺陷的种类具有重要的参考价值。     

THE MECHANISM OF COPOLYMERIZATION OF VINYL AND DIVINYL MONOMER Ⅵ: A STUDY ON THE MECHANISM OF THE STRUCTURE FORMATION OF CROSSLINKED POLYSTYRENE

In order to study the mechanism of the formation of maeroporous copolymer, the overall reaction kinetics, phase separation and gelation of the S/EGDM in the presence of inert solvents and the physical properties of the eopolymer were investigated and compared with the corresponding system of S/DVB and S/DVB/MMA. The formation of the network structure of the macroreticular polymer was studied and a model of the mechanism suggested.