在线分析技术在中国的发展

在线分析技术由于其具有实时、准确、高效的特点,近年来得到快速发展,已被广泛应用于环境、矿业、冶金、生物医药和食品等领域。重点介绍了国内X射线荧光光谱、激光诱导击穿光谱、瞬发γ中子活化、双能量γ射线透射、原子荧光光谱、近红外光谱和质谱法等在线分析技术近十年来的发展和应用情况,并对在线分析技术未来发展趋势进行了展望。     

高纯四氯化锗测试样品的采集和制备方法研究

针对光纤级高纯四氯化锗(99.999999%)中痕量含氢杂质吸收峰红外透过率检测(FTIR)用试样的采集,以及痕量金属杂质的电感耦合等离子体质谱法(ICP-MS)测定用试样的制备方法进行了系统研究。设计开发了用于检测痕量含氢杂质吸收峰红外透过率的样品采集实验装置,实现了含氢杂质(如—OH、—CH、HCl等)吸收峰的红外透过率在线连续测试,试样采集过程全密闭进行,避免了采样过程的二次污染,采样过程流程简短,操作简便;实验优选了在制备ICP-MS法测定痕量金属杂质用的试样过程中消除四氯化锗基体干扰、防止砷等易挥发杂质损失以及防止样品处理过程污染试样的制样方法,实现了试样制备过程二次污染源的有效控制,制样过程试剂消耗量少,制备时间短,待测元素无损失。     

N,O-Nucleoside Analogues: Metabolic and Apoptotic Activity

Two new families of N,O-nucleoside analogues containing the anthracene moiety introduced through the nitrosocarbonyl ene reaction with allylic alcohols were prepared. The core structure is an isoxazolidine heterocycle that introduces either atom either a phenyl ring or dimethyl moiety at the C3 carbon. Different heterobases were inserted at the position 5 of the heterocyclic ring. One of the synthesized compounds demonstrated a good capacity to induce cell death and an appreciable nuclear fragmentation was evidenced in treated cells.     

Kinetics of D,L–Lactide Polymerization Initiated with Zirconium Acetylacetonate

The kinetic of D,L-lactide polymerization in presence of biocompatible zirconium acetylacetonate initiator was studied by differential scanning calorimetry in isothermal mode at various temperatures and initiator concentrations. The enthalpy of D,L-lactide polymerization measured directly in DSC cell was found to be ΔH=−17.8±1.4 kJ mol⁻¹. Kinetic curves of D,L-lactide polymerization and propagation rate constants were determined for polymerization with zirconium acetylacetonate at concentrations of 250–1000 ppm and temperature of 160–220 °C. Using model or reversible polymerization the following kinetic and thermodynamic parameters were calculated: activation energy E_a=44.51±5.35 kJ mol⁻¹, preexponential constant lnA=15.47±1.38, entropy of polymerization ΔS=−25.14 J mol⁻¹ K⁻¹. The effect of reaction conditions on the molecular weight of poly(D,L-lactide) was shown.     

Trends in the use of passive sampling for monitoring polar pesticides in water

The presence of polar pesticides in environmental waters is a growing problem. After application their migration into the aqueous phase is promoted by their high water solubility. Transport processes are usually complex and inputs are generally stochastic; this makes monitoring of this class of pesticides challenging using low volume spot samples of water. Recently there has been a trend to use passive samplers to monitor pesticides in river catchments as it is an in-situ time integrative sampling technique. The three main types of device used for this purpose are, Chemcatcher®, POCIS and o-DGT. This article reviews the fate and current state-of-the-art for monitoring polar pesticides in aqueous matrices. Principles and the theory of passive sampling and strategies for passive sampler design and operation are presented. Advances in the application of passive sampling devices for measuring polar pesticides are extensively critiqued; future trends in their use are also discussed.     

Shape effect on the size and dimension dependent order-disorder transition temperatures of bimetallic alloys

Chemically ordered bimetallic nanocrystals may be promising candidates for the future magnetic-storage applications. In order to theoretically understand the order-disorder transition in nanoscale, a model based on the previous result for the size and dimension dependent melting temperature is developed to describe the effects of sizes, shapes and dimensions on order-disorder transition temperatures (T_OD) of bimetallic alloys. The results show that T_OD drops as size decreases, shape factor increases and dimension decreases. Also, the shape effect on T_OD cannot be neglected. Among these effects on T_OD, size is the strongest, while shape is the weakest. All these conclusions have been compared and confirmed by the recent simulations and experiments.     

Ab-initio calculations of electronic structure and optical properties of TiAl alloy

The electronic structures and optical properties of TiAl intermetallic alloy system are studied by the first-principle orthogonalized linear combination of atomic orbitals method. Results on the band structure, total and partial density of states, localization index, effective atomic charges, and optical conductivity are presented and discussed in detail. Total density of states spectra reveal that (near the Fermi level) the majority of the contribution is from Ti-3d states. The effective charge calculations show an average charge transfer of 0.52 electrons from Ti to Al in primitive cell calculations of TiAl alloy. On the other hand, calculations using supercell approach reveal an average charge transfer of 0.48 electrons from Ti to Al. The localization index calculations, of primitive cell as well as of supercell, show the presence of relatively localized states even above the Fermi level for this alloy. The calculated optical conductivity spectra of TiAl alloy are rich in structures, showing the highest peak at 5.73 eV for supercell calculations. Calculations of the imaginary part of the linear dielectric function show a prominent peak at 5.71 eV and a plateau in the range 1.1-3.5 eV.     

利用阿秒激光追踪和控制原子分子内部电子的运动

随着强激光技术的快速发展, 在物质与激光相互作用下,实验上发现了很多新奇的物理现象。这些现象成功地被各种理论模型和数值模拟所解释和证明。一种很重要的现象就是所谓的高次谐波产生：在原子和分子与强激光相互作用时, 能够放出能量为基频光子能量几倍到几百倍的大能量光子。在实验上, 人们已经可以通过合成截止频率附近的几个谐波来产生脉冲长度在阿秒量级的激光脉冲（1阿秒=10-18秒）。阿秒脉冲的获得开启了超快科学一个全新的领域：人们可以在电子运动的自然时间尺度上去探测和操控原子分子内部电子的运动,这是继飞秒科学后人们操控微观世界物质运动的又一大飞跃。在本文中,我们就最近几年我们在理论上所开展的阿秒物理做一个简单的综述,重点强调利用阿秒光去控制电子的电离动力学以及探测分子内部电子运动.     

胶体铁磁流体的光子特性研究

这篇综述回顾了我们今年来在铁磁流体方面的一些研究工作。铁磁流体是一种纳米磁颗粒或亚铁磁颗粒悬浮在基液（如：水或煤油）中形成的悬浮液。铁磁流体之所以受到广泛关注,是因为它们在许多方面都有着潜在应用,例如在机械工程和生物医学等领域。再次综述中,我们首先介绍了铁磁流体的场感应各向异性结构,然后,介绍了几种铁磁流体基软物质材料的光学性质,即：光学负折射、磁控光子待隙和非线性光学响应。我们采用的研究方法主要是分子动力学模拟,有效煤质近似和有限元模拟.     

Ni原子双飞秒脉冲激光诱导击穿光谱的信号增强研究

在大气环境下采用波长为800nm,脉宽为30fs的飞秒激光研究了Ni的双脉冲激光诱导击穿光谱,与单飞秒脉冲激光诱导击穿光谱相比,双飞秒脉冲在最优的双脉冲相对延时下,其信号强度增强接近10倍,实验研究了双脉冲相对延时在0-1300ps范围内不同延时对激光诱导击穿光谱信号强度增强因子的影响。整个相对延时区域可以分为三个阶段：在0-50ps区域内信号增强因子是一个持续增大的过程,在50ps左右,达到一个最大值;在50-300ps区域内,信号增强因子呈现出一个先下降后上升的过程;在300-1300ps,信号增强因子基本保持不变。