Real‐time lock‐in energy loss imaging with a novel high‐speed image processing CCD video camera

We have developed a high‐speed image processing CCD video camera for real‐time energy‐loss imaging using a conventional electron microscope with an energy‐loss imaging facility. As an initial demonstration of real‐time lock‐in energy‐loss imaging, a background‐subtracted energy‐loss image was observed by attaching the high‐speed image processing CCD video camera to an analytical electron microscope equipped with a floating‐type energy‐loss imaging analyser. Copyright © 2003 John Wiley & Sons, Ltd.     

Variable low-mass filtering using an electrodynamic ion funnel

An adjustable low-mass filter has been developed for an electrospray ionization (ESI) source to block ions associated with unwanted background species from entering the mass spectrometer. The low-mass filter is made by using an adjustable potential energy barrier from the conductance-limiting plate of an electrodynamic ion funnel, which prohibits species with higher ion mobilities from exiting the ESI source. We show that this arrangement provides a linear voltage adjustment for low-mass filtering from m/z 0 to 500. Mass filtering above m/z 500 is also performed; however, higher-mass species are attenuated. The mass filter was tested with a liquid chromatography/mass spectrometry (LC/MS) analysis of a bovine serum albumin (BSA) tryptic digest and resulted in the ability to block low-mass, background species, which accounted for 40-70% of the total ion current immediately behind the ESI source during peak elution and detection.     

分子电子学的新进展

分子尺度电子学通过构筑基于微尺度电极和单个分子或者少量分子聚集体的"电极-分子-电极"结，研究跨越分子的电荷输运性质.它将分子本征化学特性与器件构筑相结合，考察分子的理化特性与电荷输运的构效关系，揭示微尺度的量子输运动力学原理，并探索基于分子的功能电子器件.是一个集化学、物理学与微电子学为一体的交叉学科.总结整理了分子电子学近些年在器件制备、输运机理及应用方面部分有代表性的进展.     

Three-dimensional aromaticity in deltahedral boranes and carboranes

Methods derived from topology and graph theory indicate that the deltahedral boranes B _n H _n ^2– and the corresponding carboranes C₂B_n–2H _n (6 n 12) may be regarded as three-dimensional delocalized aromatic systems in which surface bonding and core bonding correspond to -bonding and -bonding, respectively, in planar polygonal two-dimensional hydrocarbons CinnH _n ^(n–6)+ (n=5/7). The two extreme types of topologies which may be used to model core bonding in deltahedral boranes and carboranes are the deltahedral (D _n ) topology based on the skeleton of the underlying deltahedron and the complete (K _n ) topology based on the corresponding complete graph. Analyses of the Hoffmann-Lipscomb LCAO extended Hückel computations, the Armstrong—Perkins—Stewart self-consistent molecular orbital computations, and SCF MOab initio GAUSSIAN-82 computations on B₆H₆ ^2– indicate that the approximation of the atomic orbitals by the sum of the molecular orbitals, as is typical in modernab initio computations, leads to significantly weaker apparent core bonding approximated more closely by deltahedral (D _n ) topology than by complete (K _n ) topology.This work was presented at the Workshop The Modern Problems of Heteroorganic Chemistry sponsored by the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences (May 8–13, 1993).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1353–1360, August, 1993.     

A Background and noise elimination method for quantitative calibration of near infrared spectra

A new hybrid algorithm is proposed to eliminate the varying background and noise simultaneously for multivariate calibration of near infrared (NIR) spectral signals. The method is based on the use of multi-resolution, which is one of the main advantages provided by wavelet transform. The signals are firstly split into different frequency components, which keep the same data points of the original signals. In conjunction with a modified uninformative variable elimination (mUVE) criterion, the new method can be used to remove the low-frequency varying background and the high-frequency noise simultaneously. The method is successfully applied to simulated spectral data set and experimental NIR spectral data, resulting in more parsimonious multivariate models with higher precision. In addition, the proposed strategy can be applied to other spectral signals as well.     

物理化学课程“热化学”主题学习历程研究——化学师范生知识建构的文本分析

为深入了解地方性师范院校化学师范生知识建构习惯和水平，探讨他们在大学专业基础课程中的学习历程，以物理化学课程中以“融合科学读写特色”的“热化学”学案作为研究载体，研究对象在学案引导下开展自学活动，并在阅读教材和文献基础上进行科学写作。采用量表工具针对大学生自学效果和反思活动进行评价，并采用SOLO分类评价科学写作作品，采用KWL工具评价学生的科学阅读收获。结果发现研究对象学习动机不强，不擅长在新的学科知识学习中联系已有专业课程知识，基于文本学习的建构活动水平极低，可能是因为他们在应试背景下的基础知识并未形成体系，先修课程中并未培养元认知学习策略。     

Implementation of a general multireference configuration interaction procedure with analytic gradients in a semiempirical context using the graphical unitary group approach

The graphical unitary group approach has been applied in an efficient implementation of a general multireference configuration interaction (MRCI) method for use with small active molecular orbital spaces in a semiempirical framework. Gradients can be computed analytically for molecular orbitals from a closed-shell or a half-electron open-shell Hartree-Fock calculation. CPU times for single point energy and gradient calculations are reported. The code allows MRCI geometry optimizations of large molecules, as illustrated for the singlet ground state and the four lowest triplet states of fullerene C(76).     

Hyphenation of column liquid chromatography and Raman spectroscopy via a liquid-core waveguide: chemometrical elimination of spectral eluent background

In column liquid chromatography (LC) coupled to conventional Raman spectroscopy (RS) removal of the spectral background of the eluent is often demanding, because of the strong signals of the organic modifier. A new chemometrical method is proposed, called the eluent background subtraction (EBS) method, which can correct for small shape and intensity differences of the eluent spectra. The variations in the eluent spectra are modelled using principal component analysis (PCA). The PCA loading vectors are subsequently used for eluent background correction of the elution spectra of the analyte. The loading vectors are fitted under these spectra by an asymmetric least-squares method. This method was successfully applied under various experimental conditions and performed much better than conventional background correction methods. Analyte detectability was improved by (weighted) averaging of all elution spectra and smoothing via a p-spline function.     

基于多背景模型的海面运动目标检测

提出一种在反射光较强的条件下基于多背景模型的海面运动目标检测方法.使用基于统计模型的变化检测方法将被监控场景区分为海浪波动显著的背景区域和海浪波动不显著的背景区域;对这两种区域中的像素点分别以Weibull分布模型和Gauss分布模型建立背景模型;使用建立的背景模型检测海面的运动目标.实验结果表明,在海面反射光较强且波浪波动较大的情况下,用该方法可以比较准确地检测到海面的运动目标.     

青海省水利建设管理问题探讨

总结了1998年以来青海省水利建设管理中取得的成绩，指出了水利建设管理中存在的问题，并对今后的发展方向进行了探讨。