Evolution of excess electron binding motifs under both internal‐push (from exo C–F bonds) and external‐push (from endo C–F bonds) electron effects in endohedral metallofullerenes with endo C–F bonds

How does the endo C–F bond influence the excess electron binding motif? For lithium‐doped endohedral perfluorofullerenes with endo C–F bonds, under both internal‐push (from exo C–F bonds) and external‐push (from endo C–F bonds) electron effects, the singly occupied molecular orbital electron cloud of the sphere‐like Li···F₈@C₆₀F₅₂ (D₂) is partially dispersed within the σ_p–s antibonding orbital of endo C–F bonds and the space between C^δ+–F_endo^δ– double electric layers, which makes Li···F₈@C₆₀F₅₂ have partial excess electron (electride characteristics) and partial lithium salt characteristics, while in the tube‐like Li···F₂@C₆₀F₅₈ (C_s), as the Li is changing from approaching F to keeping away from F and to approaching another one, the singly occupied molecular orbital electron cloud is mainly dispersed from within the p orbital of the short endo C–F bond to within the middle of the two F atoms and again to within the p orbital of the short endo C–F bond, which indicates an evolution from lithium salt characteristic to excess electron characteristic, and again to lithium salt characteristic. Copyright © 2012 John Wiley & Sons, Ltd.     

手持红外热像仪自动对焦电路的设计与实现

自动对焦可以快速、准确地将镜头调节到最佳位置,但目前该方式在算法和电路设计上还不够成熟,制约了它的应用。通过优化电路设计,选用TMS320VC5509A、FIFO和串口FLASH等低功耗、小尺寸封装芯片组成低功耗自动对焦电路,并基于Sobel算子的Tenengrad的改进图像边缘能量评价函数,采用可变窗口、合适的阈值,配合粗调（定步长）和精调（可变步长）搜索算法,设计实现了一种手持红外热像仪快速、准确地自动对焦的电路。实验结果表明,该方法高效可行,不仅能实现手持红外热像仪对目标的快速捕获,并能降低操作强度。     

The effect of intragranular microstress in Al2O3—SiC nanocomposites

A theoretical model is established to investigate the intragranular particle residual stress in Al2O3-SiC nanocomposites.Using this model,we calculate the average compressive stress on the Al2O3 grain boundary(GB) and the average tensile stress within Al2O3 grains caused by SiC nanoparticles.The normal compressive stress strengthens the GB,and the average tensile stress weakens the grains.The model gives a reasonable interpretation of the strength changes of Al2O3-SiC nanocomposites with the number of SiC particles.     

Microstructure and surface roughness of graphite‐like carbon films deposited on silicon substrate by molecular dynamic simulation

Molecular dynamics simulations are performed on the atomic origin of the growth process of graphite‐like carbon film on silicon substrate. The microstructure, mass density, and internal stress of as‐deposited films are investigated systematically. A strong energy dependence of microstructure and stress is revealed by varying the impact energy of the incident atoms (in the range 1–120 eV). As the impact energy is increased, the film internal stress converts from tensile stress to compressive stress, which is in agreement with the experimental results, and the bonding of C‐Si in the film is also increased for more substrate atoms are sputtered into the grown film. At the incident energy 40 eV, a densification of the deposited material is observed and the properties such as density, sp³ fraction, and compressive stress all reach their maximums. In addition, the effect of impact energy on the surface roughness is also studied. The surface morphology of the film exhibits different characteristics with different incident energy. When the energy is low (<40 eV), the surface roughness is reduced with the increasing of incident energy, and it reaches the minimum at 50 eV. Copyright © 2012 John Wiley & Sons, Ltd.     

Quantitative selenium speciation in human urine by using liquid chromatography–electrospray tandem mass spectrometry

A liquid chromatography–electrospray-tandem mass spectrometry (ES-MS/MS) method was developed for the speciation analysis of four organic selenium species of relevance to human urinary metabolism, namely trimethylselenomium ion (TMSe⁺), selenomethionine (SeMet) and the two selenosugars, methyl 2-acetamido-2-deoxy-1-seleno-β-d-galactos/-glucos-amine (SeGalNAc and SeGluNAc, respectively). Their chromatographic separation was achieved by using a cation exchange pre-column coupled in-series with a reversed-phase high-performance liquid chromatography column, along with an isocratic mobile phase. Online detection was performed using ES-MS/MS in selective reaction monitoring mode. SeGalNAc was detected as the major human urinary metabolite of selenium in the samples analysed, whereas TMSe⁺ was detected in the urine of one volunteer before and after receiving a selenium supplement. SeMet was not detected as a urine excretory metabolite in this study. Spiking experiments performed with the urine samples revealed significant signal suppression caused by coeluting matrix constituents. To overcome such interferences, isotopically labelled ¹³CD₃⁸²SeGalNAc was used as an internal standard, whereas in the absence of an isotopically labelled internal standard for TMSe⁺, the standard addition method was applied. Quality control for the accurate quantitation of TMSe⁺ and SeGalNAc was carried out by analysing spiked human urine samples with appropriate selenium standards over a concentration range of 10–50 μg Se L⁻¹. The method has achieved a limit of detection in the presence of urine matrix comparable to that of HPLC-inductively coupled plasma-mass spectrometry for the four selenium species: 1.0 μg Se L⁻¹ for TMSe⁺, 5.6 μg Se L⁻¹ for SeMet, and 0.1 μg Se L⁻¹ for both SeGalNAc and SeGluNAc.     

变指数Herz-Besov-Triebel空间的刻画

建立了变指数的Herz型Besov和Triebel-Lizorkin空间的离散刻画并利用此刻画得到了拟微分算子在这些空问上的有界性.     

The Determination of Impurities in 233UO2 by Spark Source Mass Spectrometry

Abstract

A method for the determination of impurities in ²³³UO₂ has been developed and applied to the analysis of a product stream of ceramic grade ²³³UO₂ powder. The analytical method has combined isotope dilution and internal standard methods to permit the determination of impurities at concentrations between 0.1 and 500 ppm in a single sample.     

The Rapid and Non-Destructive Determination of Vanadium in Carbons by the Neutron Activation Analysis Using Gadolinium as an Internal Standard Material

Abstract

The present work deals with the determination of vanadium in high grade carbons by the thermal neutron activation using a Van de Graaff Accelerator. In this study, gadolinium oxide is used as the internal standard material, and the detection limit of this method is c. a. 1 ppm.     

Construction of Three Single‐Chain Antibody Fragment Variable Fusion Structures for Sensitive Detection of Nucleocapsid Protein of Hantaan Virus

Abstract

Three single‐chain fragment variable (scFv) fusion structures were constructed for use in rapid and sensitive detection of nucleocapsid protein (NP) of Hantaan virus. The detection of NPs on glass chips was signalized by enzyme labeling or fluorescence dye Cy3, or Cy5 cluster nanoparticles. The sensitivity of the methods with different signal systems was evaluated and compared. The detection limits of scFv‐alkaline phosphatase fusion, fluorescence labeling (scFv‐Cy3), and nanoparticles labeling (scFv‐SBP‐streptavidin‐nanoparticle) were 0.1 µg/mL, 1 ng/mL, and 0.1 ng/mL NP, respectively, which were all lower than that in a conventional enzyme‐linked immunosorbent assay (ELISA) (1 µg/mL). Twenty Hantaan virus isolates were detected using the proposed methods.     

负载型钙钛矿La0.8Sr0.2MnO3/SBA-15催化燃烧甲苯的研究

采用逐层负载-孔道内氨/水蒸气原位羟化法制备了一系列负载型钙钛矿La_0.8Sr_0.2MnO₃/SBA-15催化剂,用XRD、BET、TG-DTG、XPS、H₂-TPR等手段对催化剂的物性结构等进行了表征,并在常压连续流动固定床反应器上评价了该催化剂对甲苯催化燃烧的催化性能。结果表明,逐层负载-孔道内氨/水蒸气原位羟化法的使用有助于活性组分La_0.8Sr_0.2MnO₃进入SBA-15的孔道,并在SBA-15上形成钙钛矿结构。La_0.8Sr_0.2MnO₃/SBA-15上钙钛矿结构的形成和晶格氧的出现,可为催化剂提供较多的活性中心,有利于其催化燃烧甲苯的活性。