Synthesis and Crystal Structure of a New Penta-coordinated Cu(Ⅱ) Complex:Cu(C17H13F3O3)2·C5H5N

A new copper(Ⅱ) complex 3,Cu(C17H13F3O3)2·C5H5N,has been synthesized and characterized by single-crystal X-ray diffraction. It crystallizes in monoclinic,space group C2/c with a = 17.8511(7),b = 17.4136(7),c = 13.9425(7) ,β = 124.4830(10)°,V = 3572.5(3) 3,Z = 4,C39H29CuF6NO6,Mr = 785.17,F(000) = 1604,T = 292(2) K,Dc = 1.460 g/cm3 and μ = 0.691 mm-1. The structure was refined to R = 0.0477 and wR = 0.1110 for 2935 observed reflections with I > 2σ(I). For the title compound,X-ray analysis reveals that the copper(II) is penta-coordinated by four oxygen atoms from the corresponding 1-(4-(benzyloxy)phenyl)-4,4,4-trifluorobutane-1,3-dione ligands and one nitrogen atom of pyridine,forming a distorted square pyramidal geometry. It is found that the trifluoromethyl group,F(1)/F(1'),F(2)/F(2') and F(3)/F(3')),is disordered over two orientations in an approximate 3:1 ratio.     

Chaotic annealing with hypothesis test for function optimization in noisy environments

As a special mechanism to avoid being trapped in local minimum, the ergodicity property of chaos has been used as a novel searching technique for optimization problems, but there is no research work on chaos for optimization in noisy environments. In this paper, the performance of chaotic annealing (CA) for uncertain function optimization is investigated, and a new hybrid approach (namely CAHT) that combines CA and hypothesis test (HT) is proposed. In CAHT, the merits of CA are applied for well exploration and exploitation in searching space, and solution quality can be identified reliably by hypothesis test to reduce the repeated search to some extent and to reasonably estimate performance for solution. Simulation results and comparisons show that, chaos is helpful to improve the performance of SA for uncertain function optimization, and CAHT can further improve the searching efficiency, quality and robustness.     

Polyplatinayne/polyoxometalate composite Langmuir‐Blodgett films: Preparation,structural characterization,and potential optoelectronic applications

A new family of organometallic/inorganic composite Langmuir‐Blodgett (LB) films consisting of rigid‐rod polyplatinayne polymer ([Pt‐T(OMe‐Fl)T]_∞ or [Pt‐T(F‐Fl)T]_∞, where the triplet bonds are abbreviated by T, and fluorene ring by Fl) as the π‐conjugated organometallic molecule, polyoxometalate (POM, POM = K₃PMo₁₂O₄₀, H₃PW₁₂O₄₀, or H₆P₂W₁₈O₆₂) of the Keggin and Dawson structures as the inorganic component, and dimethyldioctadecylammonium bromide (DODA) or a mixture of octadecanoic acid (OA) and docosanoic acid (DA) as the auxiliary film‐forming agent were prepared and characterized by π–A isotherms, UV–Vis absorption spectra, photoluminescence spectra, atomic force microscopy imaging, scanning tunneling microscopy, and low‐angle X‐ray diffraction. Our experimental results indicate that steady, even, and ordered Langmuir and LB films are formed in pure water and polyoxometalate subphases. It was shown that the POM molecules are probably embedded inside the polyplatinayne molecules in the LB film structure and they can quench the luminescence of the Pt polyyne. These Pt‐polyyne based LB films display interesting electric conductivity behavior. [Pt‐T(OMe‐Fl)T]_∞/DODA/HPW₁₂ monolayer film shows a good electrical conductivity, and the tunneling current amounts to ±100 nA when the voltage is set at ±8 V. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3193–3206, 2008     

什么是Bio-X?

最近,在科学辞汇中出现了一个新的名词———Ｂｉｏ-Ｘ,它是由美籍华裔物理学家、1998年诺贝尔物理学奖得主朱棣文发起,在斯坦福大学建立的一个新的研究中心,称为“生物爱克斯(Ｂｉｏ-Ｘ)中心”.据称将投资15亿美元,包括建造约18万平方米的新大楼.Ｂｉｏ-Ｘ中心由该校文理...     

大型台车式电阻炉预测模糊温度控制系统

针对大型台车式电阻炉具有大滞后,大惯性,严重非线性的特性,提出了由预测控制和模糊控制相结合的预测模糊控制算法,同时也介绍了预测模糊控制算法在电阻炉计算机控制系统中的应用,实际运行效果良好.     

Catalyst-free and solvent-free method for the synthesis of quinoxalines under microwave irradiation

A facile procedure for the synthesis.of quinoxalines is being reported starting from benzil and 1,2-diaminobenzene. Thereactions were carried out catalyst-free, solvent-free and under microwave irradiation conditions in high yield (84-98%) with short time (3-6 rain) and environmental benign, as well as convenient operation. The structures of all the compounds have been confirmed on the basis of their IR, 1H NMR, and/or 13C NMR, mass spectral data.     

对溴偶氮氯膦流动注射分光光度法测定岩矿中的钪

本文研究了对溴偶氮氯膦与钪在盐酸介质中的显色反应。在波长740nm,络合物的摩尔吸光系数为7.0×10~4,7～18μg Sc_2O_3/25ml符合比尔定律。采用流动注射分光光度法,联合使用微型计算机,测出工作曲线的线性范围为5～45μg Sc_2O_3/25ml,比普通分光光度法扩大1.5倍。应用于测定岩矿中的微量钪,方法快速、准确。     

Convex functions on Grassmannian manifolds and Lawson-Osserman problem

We derive estimates of the Hessian of two smooth functions defined on Grassmannian manifold. Based on it, we can derive curvature estimates for minimal submanifolds in Euclidean space via Gauss map as in [Y.L. Xin, Ling Yang, Curvature estimates for minimal submanifolds of higher codimension, arXiv: 0709.3686; 24]. In this way, the result for Bernstein type theorem done by Jost and the first author could be improved.