Synthesis of ternary and quaternary graphite intercalation compounds containing alkali metal cations and diamines

A series of ternary graphite intercalation compounds (GICs) of alkali metal cations (M = Li, Na, K) and diamines [EN (ethylenediamine), 12DAP (1,2-diaminopropane), and DMEDA (N,N-dimethylethylenediamine)] are reported. These include stage 1 and 2 M-EN-GIC (M = Li, d(i) = 0.68-0.84 nm; M = Na, d(i) = 0.68 nm), stage 2 Li-12DAP-GIC (d(i) = 0.83 nm), and stage 1 and 2 Li-DMEDA-GIC (d(i) = 0.91 nm), where d(i) is the gallery height. For M = Li, a perpendicular-to-parallel transition of EN is observed upon evacuation, whereas for M = Na, the EN remains in parallel orientation. Li-12DAP-GIC and Li-DMEDA-GIC contain chelated Li(+) and do not show the perpendicular-to-parallel transition. We also report the quaternary compounds of mixed cations (Li,Na)-12DAP-GIC and mixed amines Na-(EN,12DAP)-GIC, with d(i) values in both cases between those of the ternary end members. (Li,Na)-12DAP-GIC is a solid solution with lattice dimensions dependent on composition, whereas for Na-(EN,12DAP)-GIC, the lattice dimension does not vary with amine content.     

9-H-9-Borafluorene dimethyl sulfide adduct: a product of a unique ring-contraction reaction and a useful hydroboration reagent

The dimethyl sulfide adduct 2(DMS) is a crystalline storage form of the unstable hydroboration reagent 9-H-9-borafluorene (2); 2(DMS) is available by the addition of DMS to either in situ generated [2](2) or 1,2-(2,2'-biphenylylene)diborane(6) (7).     

利用提升小波的蛋白质相互作用特征提取

利用提升小波从蛋白质序列中提取出它们相互作用的频谱特征,经支持向量机训练学习后,用于预测蛋白质间的相互作用.模拟计算结果表明,在阳性数据和阴性数据平衡的前提下,利用提升小波获取的低维蛋白质相互作用特征向量可以得到较高预测精度.进一步阐述了不同物种的蛋白质相互作用网络有着不同特征,为了得到更准确的预测结果,需要利用不同的方法提取蛋白质相互作用的特征.     

一种新的自动调焦方法—离轴探测法

本文提出了的种新的自动调焦方法——离轴探测法,此法没用任何附加元件,结构简单、装调容易、线性度好、灵敏度高、调焦范围大、实用性强;介绍了此法的原理、理论计算结果及实验结果;给出了应用实例.     

C_0复杂度的改进及其在证券市场中的应用

系统地分析了Lemple-Ziv复杂性度量方法的应用过程中,将实际信号(时间序列)转变成符号序列的诸多方法中存在的一些问题,提出了更合理兼容法.该方法可以有效地刻划各种时间序列的复杂度.文章最后动态地分析了中国证券市场的复杂性.     

交通流非参数回归模型

交通流宏观参数流量、速度和占有率在交通工程和管理中具有非常重要的作用 ,对这三者关系的刻划反映了道路本身特性和交通流的规律。到目前为止 ,基本上采用线性或非线性的参数模型来描述 ,此类模型在应用中具有一定的局限性 ,并交通变量时间序列进行预测 ,数据拟合表明 ,选择适当的核函数或邻近数以及窗宽 ,可以达到比较满意的效果     

Two-dimensional electron-hole liquid in the strong magnetic field

The Matsubara diagram technique is used to study the formation and thermodynamic properties of an electron-hole liquid (EHL) in the two-dimensional system in the transverse strong magnetic field. The system has discrete energy spectra, i.e. a motion of particles becomes “zero-dimensional”. Therefore, the exchange interaction alone is sufficient to form EHL, the correlation correction being negligible.     

On existence of quantum diffusion of 2-D electrons at the surface

A quantum diffusion of 2-D electrons at a metal substrate has been shown to arise because of surface-bulk interaction via hybridization provided that the surface Fermi momentum has been smaller than the bulk one. The diffusion coefficient D has been found to depend nonmonotonously on sample dimensions L. An initial decrease in D has turned into an increase for sufficiently large L. The minimum in D has nonanalytically depended on the hybridization constant: $\text{D}{}_{\mathrm{<mtext>min</mtext>}}\text{～g}{}^{\mathrm{<mtext>4</mtext><mtext>3</mtext>}}$. The effects predicted have resulted from the instability of the zero-component nonlinear σ-model with respect to inclusion of certain symmetry — breaking terms which have proved to increase under RG transformations.     

The space of Lorentz metrics

The set of allC ² Lorentz metrics on a non-compact four-manifold is given the Whitney fineC ² topology. It is shown that this provides the correct framework within which to discuss the global properties of spacetime manifolds in general, and the singularity theorems in particular. The main result is a theorem showing that the Robertson-Walker big bang (global infinite density singularity in the finite past) is stable under sufficiently small, but otherwise arbitrary, finiteC ² perturbations of the metric tensor.Based, in part, on a thesis submitted to the Mathematics Department of the University of Pittsburgh.