Conical Double Frequency Emission by Femtosecond Laser Pulses from DKDP

Conical double frequency emission is investigated by femtosecond laser pulses at a wavelength of 80Ohm in a DKDP crystal. It is demonstrated that the sum frequency of incident wave and its scattering wave accounts for the conical double frequency emission. The gaps on the conical rings are observed and they are very sensitive to the propagation direction, and thus could be used to detect the small angle deviation of surface direction.     

星载激光测距合作目标的光学设计

运行于空间轨道的角反射器由于受相对速度的影响,必须进行速差补偿。针对轨道高度为20000km的角反射器,确定了能够接受的直角面平面度;针对几何光学方法速差补偿的不准确,运用衍射原理,对速差补偿的效果按角差的不同进行搜索,得到了比较理想的结果,确定了角反射器的参数。     

Synthesis and Structure of a Titanocene-ferrocenyl Complex

A titanocene-ferrocenyl complex, （5-ferrocenyl-2-hydroxybenzenecarboxylato- O,O′）-bis（methylcyclopentadienyl）titanium（IV） 4, and an unexpected ionic complex, [C7H8NO3]- [（C5H5）Fe（C5H4）SO3]·H2O3 were synthesized and characterized by IR, ^1H NMR and elemental analysis. Compound 3 is of triclinic, space group P1 with a = 5.954（2）, b = 13.208（5）, c = 13.252（5） A, α = 60.993（7）,β = 84.342（8）,γ = 86.933（8）°, Z = 2, V = 906.8（6）A^3, Dc = 1.601 g/cm^3, μ（MoKα） = 0.987 mm^-1, F（000） = 452, the final R = 0.0647 and wR = 0.1333 for 2311 observed reflections （I 〉 2σ（I））. Compound 4 belongs to the monoclinic system, space group P2 1/c with α = 14.3310（9）, b = 12.5065（8）, c = 12.9406（10） A, β = 95.101（4）°, Z = 4, V = 2310.2（3） A^3, Dc = 1.513 g/cm^3, μ（MoKα） = 1.004 mm^-1, F（000） = 1088, the final R = 0.0461 and wR = 0.1048 for 2112 observed reflections （1 〉 2σ（I））.     

Three New d~(10) Coordination Polymers with Arenedisulfonates:Syntheses,Crystal Structures and Luminescent Properties

Three new cadmium or zinc arenedisulfonate complexes [Zn（bpp）2（L）]n 1, { [Cd（bpp）2（1,5-NDS）（H2O）2]·4H2O }n 2 and { [Cd（bpp）2（H2O2）2]·（1,5-NDS） } n 3 （L = 4,4′-bis（2-sulfonatostyryl）biphenyl, bpp = 1,3-di（4-pyd-dyl）propane and 1,5-NDS = 1,5-Naphthalenedisulfonate） have been synthesized from aqueous solution and structurally characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction. Crystal data for complex 1： space group P21/n, a = 10.559（3）, b = 13.138（4）, c = 17.623（5）A^°, β = 100.852（3）°, V = 2400.9（12） A^°^3 Z = 2, Dc= 1.351 g/cm^3, F（000） = 1016, μ = 0.654 mm^-1, the final R = 0.0412 and wR = 0.0994; Crystal data for complex 2： space group P^-1, a = 8.5642（19）, b = 10.076（3）, c = 12.114（3） A^°, α = 81.623（7）, β = 77.149（8）, γ = 82.787（7）°, V = 1003.6（4） A^°^3 Z = 1, Dc= 1.495 g/cm^3, F（000） = 466,μ = 0.713 mm^3, the final R = 0.0241 and wR = 0.0713; Crystal data for complex 3： space group C2/c, a = 21.6024（15）, b = 9.4608（5）, c = 18.4656（11）A^°, β = 107.359（3）°, V= 3602.0（4）A^°^3 Z = 4, Dc= 1.533 g/cm^3, F（000） = 1704,μ = 0.780 mm^-1, the final R = 0.0229 and wR = 0.0572. The X-ray single diffraction reveals that 1 exhibits a 3D metal-organic framework formed from 2D Zn（bpp）2^2＋ networks connected by L in the third dimension; 2 and 3 possess 3D and 2D architectures constructed from 1D polymeric chains through H-bond. Complexes 1-3 display photoluminescent emissions at 452 and 335 nm, respectively.     

Synthesis and Crystal Structure of a Dialkyltin Benzamidoacetate Compound {[n-Bu2Sn（O2CCH2NHCOC6H5）]2O}2·C6H6

A dialkyltin benzamidoacetate compound {[n-Bu2Sn（O2CCH2NHCOC6H5）]2O}2· C6H6 has been synthesized by the reaction of dialkyltin oxide with benzamidoacetic acid in 1：1 molar ratio, and its structure was determined by X-ray single-crystal diffraction. The crystal belongs to orthorhombic, space group Pca21, with a = 1.9134（4）, b = 1.9605（4）, c = 2.0657（4） nm, Z = 4, V = 7.749（3） nm^3, Dc = 1.054 mg·m^-3,μ（MoKa） = 1.337 mm^-1, F（000） = 3576, the final R = 0.0405 and wR = 0.0860. According to the structural analysis, the tin atom adopts a distorted five-coordinate trigonal bipyramidal geometry, and the dimer structure is shaped by one planar four-membered Sn2O2 ring.     

蛋白质折叠类型的分类建模与识别

蛋白质的氨基酸序列如何决定空间结构是当今生命科学研究中的核心问题之一. 折叠类型反映了蛋白质核心结构的拓扑模式, 折叠识别是蛋白质序列-结构研究的重要内容. 我们以占Astral 1.65序列数据库中α, β和α/β三类蛋白质总量41.8%的36个无法独立建模的折叠类型为研究对象, 选取其中序列一致性小于25%的样本作为训练集, 以均方根偏差(RMSD)为指标分别进行系统聚类, 生成若干折叠子类, 并对各子类建立基于多结构比对算法(MUSTANG)结构比对的概形隐马尔科夫模型(profile-HMM). 将Astral 1.65中序列一致性小于95%的9505个样本作为检验集, 36个折叠类型的平均识别敏感性为90%, 特异性为99%, 马修斯相关系数(MCC)为0.95. 结果表明: 对于成员较多, 无法建立统一模型的折叠类型, 基于RMSD的系统分类建模均可实现较高准确率的识别, 为蛋白质折叠识别拓展了新的方法和思路, 为进一步研究奠定了基础.     

A novel correlation for estimation of hydrate forming condition of natural gases

An inherent problem with natural gas production or transmission is the formation of gas hydrates, which can lead to safety hazards to production/ transportation systems and to substantial economic risks. Therefore, an understanding of conditions where hydrates form is necessary to overcome hydrate related issues. Over the years, several models requiring more complicated and longer computations have been proposed for the prediction of hydrate formation conditions of natural gases. For these reasons, it is essential to develop a reliable and simple-to-use method for oil and gas practitioners. The purpose of this study is to formulate a novel empirical correlation for rapid estimation of hydrate formation condition of sweet natural gases. The developed correlation holds for wide range of temperatures (265–298 K), pressures (1200 to 40000 kPa) and molecular weights (16−29). New proposed correlation shows consistently accurate results across proposed pressure, temperature and molecular weight ranges. This consistency could not be matched by any of the widely accepted existing correlations within the investigated range. For all conditions, new correlation showed average absolute deviation to be less than 0.2% and provided much better results than the widely accepted existing correlations.     

LYAPOUNOV EXPONENTS AND LAW OF LARGE NUMBERS FOR RANDOM WALK IN RANDOM ENVIRONMENT WITH HOLDING TIMES

In this article, the authors mainly discuss the law of large number under Kalikow＇s condition for multi-dimensional random walks in random environment with holding times. The authors give an expression to the escape speed of random walks in terms of the Lyapounov exponents, which have been precisely used in the context of large deviation.     

多元随机序列泛函的强偏差定理

利用熵密度和样本偏差率的概念,建立了多元随机序列泛函关于条件期望的用不等式表示的强极限性质(称之为强偏差定理),在推论部分得到了非齐次马氏链的强偏差定理和随机条件概率的调和平均值的极限性质等相关结论.证明中给出了将条件矩母函数应用于研究多元随机序列泛函的强极限性质的一种途径.     

无穷维自回归过程的中偏差原理

本文考虑无穷维自回归过程经验协方差函数的中偏差原理,仅对自回归过程的随机扰动项做了高斯可积性的假设,这个条件比[4]中的对数Sobolev不等式要弱很多.主要利用了m-相依随机变量的中偏差结果和Ellis-Grtner定理,推广了[6]的结果.