Möbius环并苯的分子对称性

一般来说, 点群理论认为Möbius带环分子最高的对称性只能是C₂. 本文讨论了由18个苯环组成的环并苯的异构体分子, 包括柱面的Hückel型分子(HC-[18])和扭转180°的Möbius带环分子(MC-[18]). 结果表明除了点对称性外, Möbius带环分子还存在一种可称为环面螺旋旋转(TSR)变换的对称性, 为此还引用了环面正交曲线坐标系. 此外, 还讨论了这些分子关于TSR对称性匹配的原子集和原子轨道(AO)集. 根据TSR对称性的循环群特征, 可以建立此类群的不可约表示及有关特征标. 这类分子的分子轨道(MO)关于TSR群的不可约表示是纯的, 然而所含的相应的原子轨道对称性匹配的线性组合(SALC-AO)成分可以是多种的.     

Solution structure and conformational dynamics of deoxyxylonucleic acids (dXNA): an orthogonal nucleic acid candidate

Orthogonal nucleic acids are chemically modified nucleic acid polymers that are unable to transfer information with natural nucleic acids and thus can be used in synthetic biology to store and transfer genetic information independently. Recently, it was proposed that xylose-DNA (dXNA) can be considered to be a potential candidate for an orthogonal system. Herein, we present the structure in solution and conformational analysis of two self-complementary, fully modified dXNA oligonucleotides, as determined by CD and NMR spectroscopy. These studies are the initial experimental proof of the structural orthogonality of dXNAs. In aqueous solution, dXNA duplexes predominantly form a linear ladderlike (type-1) structure. This is the first example of a furanose nucleic acid that adopts a ladderlike structure. In the presence of salt, an equilibrium exists between two types of duplex form. The corresponding nucleoside triphosphates (dXNTPs) were synthesized and evaluated for their ability to be incorporated into a growing DNA chain by using several natural and mutant DNA polymerases. Despite the structural orthogonality of dXNA, DNA polymerase β mutant is able to incorporate the dXNTPs, showing DNA-dependent dXNA polymerase activity.     

微波法合成2-羟乙基苯并[d]异噻唑-3(2H)-酮

以苯并异噻唑-3(2H)-酮(BIT)及氯乙醇为原料微波法合成了2-羟乙基苯并[d]异噻唑-3(2H)酮。考察了氢氧化钠量,氯乙醇用量,反应时间,反应温度对反应的影响,经正交实验设计得到了最佳反应条件,最佳反应条件下收率为83.3%。结果表明,与传统工艺相比,微波技术合成2-羟乙基苯并[d]异噻唑-3(2H)-酮的方法具有操作方便、收率高等特点,具有一定的应用价值。     

Exact solution of the modified Pöschl–Teller potential in the tridiagonal representation

The Schrödinger equation with the modified Pöschl‐Teller (MPT) potential is studied by working in a complete square integrable basis that supports a tridiagonal matrix representation of the wave operator. The resulting three‐term recursion relation for the expansion coefficients of the wavefunction is presented, and the wavefunctions are expressed in terms of the Jocobi polynomial. The discrete spectrum of the bound states is obtained by diagonalization of the recursion relation. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Spegtrophotometrig Determination of α -Tocopherol Acetate in Soft Capsules

Abstract

Two spectrophotometric methods have been described for the determination of α -tocopherol acetate (vitamin E) in soft capsules. The first method applies the orthogonal function method under least squares. The quadratic coefficients calculated over the wavelength range 277 - 304 nm at 4-nm intervals in chloroform were reproducible and independent of ethyl oleate concentration. The second method applies the second derivative (D₂) to correct for irrelevant absorbance due to ethyl oleate The peak trough amplitude at 271 - 287 nm was in linear correlation to the concentration of vitamin E. The recoveries obtained using the proposed methods agreed with those obtained using the official proceduce.     

基于鱼群算法的OFDMA自适应资源分配

针对多用户正交频分多址系统自适应资源分配问题, 提出了一种新的子载波和基于鱼群算法的功率自适应分配算法. 该算法首先对总功率在子载波间均等分布的条件下进行子载波分配,然后引入鱼群算法并根据给出的兼顾用户公平性与系统容量的适应度函数,通过全局搜索实现用户间的功率分配. 仿真结果表明,新算法在保证用户公平性的同时, 还实现了系统总的传输速率最大化. 关键词： 多用户正交频分多址 资源分配 鱼群算法 速率最大化     

OnPLS—a novel multiblock method for the modelling of predictive and orthogonal variation

This paper presents a new multiblock analysis method called OnPLS, a general extension of O2PLS to the multiblock case. The proposed method is equivalent to O2PLS in cases involving only two matrices, but generalises to cases involving more than two matrices without giving preference to any particular matrix: the method is fully symmetric. OnPLS extracts a minimal number of globally predictive components that exhibit maximal covariance and correlation. Furthermore, the method can be used to study orthogonal variation, i.e. local phenomena captured in the data that are specific to individual combinations of matrices or to individual matrices. The method's utility was demonstrated by its application to three synthetic data sets. It was shown that OnPLS affords a reduced number of globally predictive components and increased intercorrelations of scores, and that it greatly facilitates interpretation of the predictive model. Copyright © 2011 John Wiley & Sons, Ltd.     

On a discrete‐time collocation method for the nonlinear Schrödinger equation with wave operator

We consider a discrete‐time orthogonal spline collocation scheme for solving Schrödinger equation with wave operator. The scheme is proposed recently by Wang et al. (J Comput Appl Math 235 (2011), 1993–2005) and is showed to have high‐order convergence rate when a parameter θ in the scheme is not less than $\frac{1}{4}$. In this article, we show that the result can be extended to include $\theta\in(0,\frac{1}{4})$ under an assumption. Numerical example is given to justify the theoretical result. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013     

Complexes of Gorenstein Flat Modules and Gorenstein Cotorsion Modules

A complex (C, δ) is called strongly Gorenstein flat if C is exact and Ker δ ⁿ is Gorenstein flat in R-Mod for all n ∈ ?. Let 𝒮𝒢 stand for the class of strongly Gorenstein flat complexes. We show that a complex C of left R-modules over a right coherent ring R is in the right orthogonal class of 𝒮𝒢 if and only if C ⁿ is Gorenstein cotorsion in R-Mod for all n ∈ ? and Hom^.(G, C) is exact for any strongly Gorenstein flat complex G. Furthermore, a bounded below complex C over a right coherent ring R is in the right orthogonal class of 𝒮𝒢 if and only if C ⁿ is Gorenstein cotorsion in R-Mod for all n ∈ ?. Finally, strongly Gorenstein flat covers and 𝒮𝒢^⊥-envelopes of complexes are considered. For a right coherent ring R, we show that every bounded below complex has a 𝒮𝒢^⊥-envelope.