New organically templated gallium oxalate-phosphate structures based on Ga4(PO4)4(C2O4) building unit

Five organic-inorganic hybrid gallium oxalate-phosphates, [Ga₂(PO₄)₂(H₂O)(C₂O₄)_0.5](C₃N₂H₁₂)_0.5(H₂O) (1), [Ga₂(PO₄)₂(C₂O₄)_0.5](C₂N₂H₁₀)_0.5(H₂O) (2), [Ga₂(PO₄)₂(C₂O₄)_0.5](C₃N₂H₁₂)_0.5 (3), [Ga₂(PO₄)₂(H₂PO₄)_0.5(C₂O₄)_0.5](C₄N₃H₁₆)_0.5 (H₂O)_1.5 (4) and [Ga_2.5(PO₄)_2.5(H₂O)_1.5(C₂O₄)_0.5](C₄N₃H₁₅)_0.5 (5), have been synthesized by using 1,3-diaminopropane, ethylenediamine and diethylene triamine as structure-directing agents under hydrothermal condition. The structures of 1-5 are based on Ga₄(PO₄)₄(C₂O₄) building unit made up from Ga₂O₈(C₂O₄) oxalate-bridging dimer and alternating PO₄ and GaO₄ tetrahedral units. Compound 1 is layered structure where the building units link together in the same orientation. Corner sharing of these similar layers result in three-dimensional (3-D) structure 2. However, in compound 3, the building units arrange in a wave-like way to generate two types of eight member ring (8MR) channels. Both 4 and 5 contain the layers where the building units have an opposite orientation. Those layers are linked by H₂PO₄ group and Ga(PO₄)(H₂O)₃ cluster, respectively, to form 3-D frameworks with 12MR large pore channels. Compounds 2-5 exhibit intersecting 3-D channels where the protoned amines are located.     

改进二元分布估计算法求解置换流水车间调度问题

针对置换流水车间调度这类组合最优化问题的求解,提出了一种改进二元分布估计算法(Improved binary estimation distribution algorithm, I-EDA)。算法以二元分布估计算法为架构,使用NEH(Nawaz-Enscore-Ham)启发式算法生成初始解,提高了初始解的质量;通过对优势解的统计采样构建位置矩阵模型和链接矩阵模型,依照两个矩阵模型的合并概率组合链接区块产生子代。提出了NEH插入式重组策略和基于位置概率的交换策略和两种全新局部搜索机制替代原二元分布估计算法的相邻交换法,以进一步筛选优势解。最后通过对Reeves标准测试集的仿真实验和算法比较验证了所提出算法的有效性。     

Generation of three-dimensional block-structured grids based on rotation of two-dimensional multiply connected cross sections

An algorithm for generating curvilinear block-structured grids in axisymmetric three-dimensional domains of any connectivity is developed. The organization of the connection between the blocks is automated. The grids constructed are used to compute ideal gas steady flows past axisymmetric bodies at a nonzero angle of attack.     

The importance of short structural motifs in protein structure analysis

Summary Proteins tend to use recurrent structural motifs on all levels of organization. In this paper we first survey the topics of recurrent motifs on the local secondary structure level and on the global fold level. Then, we focus on the intermediate level which we call the short structural motifs. We were able to identify a set of structural building blocks that are very common in protein structure. We suggest that these building blocks can be used as an important link between the primary sequence and the tertiary structure. In this framework, we present our latest results on the structural variability of the extended strand motifs. We show that extended strands can be divided into three distinct structural classes, each with its own sequence specificity. Other approaches to the study of short structural motifs are reviewed.     

Hybrid Organic-Inorganic Copolymers Based on Oxo-Hydroxo Organotin Nanobuilding Blocks

Hybrid organic-inorganic copolymers have been prepared following the nano-building blocks approach. The oxo-hydroxo butyltin macro-cation, {(BuSn)₁₂O₁₄(OH)₆}²⁺, which is prepared by hydrolysis of butyltin triisopropoxide, is first functionalized by anchoring onto it methacrylate groups through electrostatic interactions. Then, to turn these isolated nano-building blocks into hybrid copolymers, they were assembled by initiating the organic polymerization of the methacrylate functions.¹³C and¹¹⁹Sn NMR, in the solid state, and QELS evidences of the formation of hybrid organic-inorganic copolymers are reported.     

Synthesis of ring modified prostaglandins

The total syntheses of the ring modified prostaglandins 8–12, 16, 18, 20, and 22 are described.     

Asymmetric total synthesis of enantiopure (−)-methyl jasmonate via catalytic asymmetric intramolecular cyclopropanation of α-diazo-β-keto sulfone

A new asymmetric total synthesis of enantiopure (−)-methyl jasmonate is described. This synthesis was accomplished starting from the new enantiopure building block prepared via the catalytic asymmetric intramolecular cyclopropanation (IMCP) of the α-diazo-β-keto 1-naphthyl sulfone, which was devised to give good selectivity both in the IMCP reaction and in the C-alkynylation of the intermediate required for the total synthesis of enantiopure (−)-methyl jasmonate.     

Synthesis and structure of a HgI2 coordination polymer with novel rigid N-donor ligand

Solution reaction of mercury iodide with organic multifunctional ligand 2, 3-di (4-pyridyl)-2, 3-butanediol (dpb) generated a 1D polymer [(HgI₂)₂(dpb)₂(DMSO)₂] _n 1, and the crystal structure has been determined (C₁₈H₂₈HgI₂N₂O₄S₂), M _r=854.93, a=10.821(2), b=25.196(5), c=10.039(2)?, space group Pnma, Z=4, and V=2737.0(9)?³. In 1 the rigidity of HgI₂ and dpb make it a zigzag structure.     

The existence of symmetric designs with parameters (105, 40, 15)

The existence of symmetric designs with parameters (105, 40, 15) was shown. © 1999 John Wiley & Sons, Inc. J Combin Designs 7: 17–19, 1999     

自动快速燃烧炉-离子色谱联用技术检测水泥等建材中的氯

建立了一种全新的以燃烧方法处理固体样品的装置——自动快速燃烧炉(AQF)与离子色谱联用的技术,检测建筑材料中氯的方法.该方法将AQF的快速处理样品的能力和离子色谱的准确性好、灵敏度高的特点相结合,可以连续批量处理样品,平均在18 min之内完成一个样品的检测.方法的线性、重现性、检测限均令人满意.还进行了水提法处理待测样品,将其结果与AQF处理的结果相比较,结果表明AQF处理的方法具可行性.