Bonding of the chain structure for novel boranes B_(3k+)H_(5k+p+3)~-

The molecular orbitals obtained from conventional quantum chemistry calculations, are expressed in terms of symmetrized valence bond functions of fragment, and a direct picture of chemical bonding can be drawn easily. This method is utilized, together with extended Huckel calculations, to interpret the bonding properties of a centipede-like chain structure for novel laser-producing boranes B3k+pH5k+p+3- which is constructed from the repeated unit B3H5 linked to each other by three B-H-B bonds.     

Syntheses of a new type of chiral phosphines from glucose

Methyl 3-deoxy-3-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (1) and methyl 2-deoxy-2-(diphenylphosphino)-4,6-O-benzylidene-α-D-altropyranoside (2) were prepared from methyl 2,3-anhydro-4,6-O-benzylidene-O-D-mannopyranoside and methyl 2,3-anhydro-4,6-O-benzyl-idene-α-D-allopyranoside,respectively,via regioselective and stcreospecific ring-opening reactions in high yields.Compounds 1 and 2 were oxidized to give the corresponding phosphine oxides (3 and 4).     

CRYSTAL STRUCTURE AND POWDER DIFFRACTION OF Na5Y（WO4）4

<正> Title compound Na5Y (WO4)4 (Mr = 1195. 24) crystallizes in the space group I41/a with the cell parameters a= 11. 447(7), c= 11. 336(1) A , Z = 4, V = 1485(2) A3, A = 5. 34 g/cm3. A(MoKα) = 0. 71069 A. F(000) = 2702, final R = 0. 045,Rw = 0. 054 for 936 observed reflections with I≥3σ(I). The title compound has a scheelite structure.In this paper, we also give the X-ray powder diffraction data of Na5Y(WO4)4 obtained by using a D/max-ra type diffractometer.     

Wormhole Propagation Behavior Under Reservoir Condition in Carbonate Acidizing

In carbonate reservoirs, acid is injected into the formation under breakdown pressure to react with the rock to remove the contaminations caused by drilling and production, which is called carbonate acidizing in reservoir development. In carbonate acidizing, acid flows selectively through large pores to create wormholes. Wormhole propagation under experimental condition has been studied by many experts. In this paper, a model which couples a two-scale continuum model simulating wormholing in the invaded zone and a reservoir flow model for the compressed zone was used to study the wormhole propagation behavior under reservoir condition. In this model, the porosity values which are uniformly distributed used in former literature follow the normal law. Based on the model, we first compared the results of the two porosity generation methods, and then studied the wormhole propagation behavior under reservoir condition, and finally simulated a two-layer formation to study the effects of distance and permeability ratio between the two layers. The results show that the normally distributed porosities simulate wormholing better. The effect of compressed zone on wormhole propagation increases with the decrease of compressibility factor and wormhole has a maximal value in length. The effect of distance between the two layers on wormhole lengths and acid distributions can be divided into three zones based on the wormhole length in the lower layer. A critical value of permeability ratio between the two layers exists, below and above which the wormhole length in the low permeability layer decreases sharply and almost keeps constant, respectively.     

光学薄膜厚度修正挡板的设计

本文论述一种用于镀制光学薄膜的厚度修正挡板新的设计方法.我们通过应用截流蒸气云静止挡板技术和采用平面静止挡板透视投影法来设计光学薄膜厚度修正挡板.最后给出设计和实验的结果.     

卡塞格林反射系统结构动态优化设计

本文对卡塞格林系统在焦平面上的衍射效应进行了分析,并采用有限元素光线追踪法对衍射效应进行了计算.据此,本文提出了以该衍射效应作为卡塞格林反射系统结构优化设计的目标函数,该方法具有直观和量化的优点.采用该方法对大口径反射系统结构的设计具有一定的实际意义.     

A trinuclear Mo-Fe-Mo cluster compound [Et_4N] { [Me_2dtcMo-O(μ-S)_2]_2Fe} containing dialkyldithiocarbamate ligand

A trinuclear linear Mo-Fe-Mo dialkyldithiocarbamate complex [Et4N] { [ Me2dtcMoO (μ-S)2 ]2Fe} has been obtained and structurally characterized, which contains two Me2dtcMoO-(μ-S)2 units coordinated to a central tetrahedral Fe atom. A comparison of the structural parameters indicates the metal oxidation states of 2Mo(v) Fe(III). The 1H NMR shows chemical shifts of Me2dtc ligands at 5 10.14 and 8 9.40 with the intensity ratio of 1:1. The cyclic voltammogram displays a reversible couple at - 1.41 V/ - 1.36 V responsible for 1-/2-anions of the complex and an irreversible oxidation at 0.5 V, which seems to show the apparent lack of stability for its neutral species (Me2dtcMoOS2)2Fe.     

在N_2中[V_nCr_(3-n)(μ_3-O)(μ-O_2CCH_3)_6(THF)_3]X[n=0-3,X=Cl~-,ClO_4~-,(VO_5)_(0.5)~-]及[V_nFe_(3-n)(μ_3O)(μ-O_2CCH_3)_6(THF)_3]X(n=0-3,X=Cl~-)反应行为的原位红外光谱研究

利用原位红外光谱研究标题化合物在N2 中的反应行为。发现它们在不同温度下能使乙酸分别转化为丙酮和甲烷。它们对乙酸的丙酮化反应活性顺序 :[V3OAT]>[VFe2 OAT],[V2 CrOAT]>[Fe3OAT],[VCr2 OAT]>[Cr3OAT][OAT =(μ3 O) (μ O2 CCH3) 6(THF) 3]。它们对乙酸的甲烷化反应活性顺序 :[Cr3OAT]>[VCr2 OAT],[V2 CrOAT]>[V3OAT]>[VFe2 OAT],[FeO3OAT]。对乙酸的丙酮化反应活性[Fe3OAT]明显低于 [Fe3OAH][OAH =(μ3 O) (μ O2 CCH3) 6(H2 O) 3]。对乙酸的甲烷化反应活性 [Cr3OAT]也明显低于 [CrOAH]。并对上述 [Fe3OAT],[Cr3OAT]与 [Fe3OAH],[Cr3OAH]之间差异进行了讨论。     

Lentivirus-Mediated Knockdown of CUGBP1 Suppresses Gastric Cancer Cell Proliferation In Vitro

Gastric cancer is the second most common cause of cancer-related death worldwide. This study was designed to examine the role of CUGBP1 in cell growth via an RNA interference (RNAi) lentivirus system in gastric cancer cells in vitro. The expression of CUGBP1 was much stronger in gastric cancer tissues than that in adjacent normal tissues. The lentivirus-mediated knockdown of CUGBP1 resulted in a significant reduction of CUGBP1 expression in MGC-803 gastric cancer cells. The cell viability was remarkably decreased by 50 % after 5 days of infection, as determined by MTT assay. Moreover, the size and the number of colonies formed in MGC-803 cells were markedly reduced in the absence of CUGBP1. Furthermore, the silencing of CUGBP1 downregulated the expression levels of cyclin B1 and cyclin D1, which are involved in cell cycle control. These results clearly indicated that CUGBP1 is essential for the growth of gastric cancer cells. Therefore, silencing of CUGBP1 by RNAi could be developed as a promising therapeutic approach for gastric cancer.     

越过临界状态的奇异扩散方程

本文讨论越过临界状态的奇异扩散方程Cauchy问题和带非线性边界条件的第二边值问题的可解性与不可解性.主要结果是: (1)若||u0||L1(R)< ∞,则对任意的正数T,方程的Cauchy问题在带型区域QT=R×(0,T)中不存在关于变量x为L1(R)可积的正解; (2)当且仅当T≤T0,矩形区域GT=(0,1)×(0,T)中的一类非线性边值问题存在唯一的经典解,其中T0=u0=integral from n=0 to1(u0(x)dx).