反应萃取手性分离苯基琥珀酸对映体动力学研究

通过恒界面池研究了羟丙基-β-环糊精(HP-β-CD)萃取苯基琥珀酸对映体(PSA)动力学.采用伴随化学反应的萃取理论获得萃取动力学.实验分别考察了搅拌速率、界面面积、对映体浓度和萃取剂浓度等条件对PSA对映体萃取动力学的影响.实验结果表明:HP-β-CD萃取PSA对映体的反应为快反应;对对映体反应是一级反应,对萃取剂反应是二级反应;R-PSA,S-PSA反应速率常数分别为3.4×10-2m6mol-2s-1,9.96×103m6mol-2s-1.这些数据对萃取过程的设计是很重要的.     

轻小型广角投影物镜的设计

为实现数字投影机的小型化和轻量化,设计了一款适用于0.55 inch数字微反射镜芯片的小型广角投影物镜.该投影物镜总长69 mm,全口径25 mm,由5片玻璃透镜,2片塑料透镜(4个非球面)组成.系统采用像方远心的反远距结构形式,用Zemax软件实现优化设计.F数为F/2.4,投射比为0.73∶1,即60 cm处可投射...     

Effects of shape and dopant on structural,optical absorption,Raman, and vibrational properties of silver and copper quantum clusters: A density functional theory study

We investigate the effects of shape and single-atom doping on the structural, optical absorption, Raman, and vibra- tional properties of Ag13, Ag12CUl, CUl3, and Cul2Agl clusters by using the （time-dependent） density functional the- ory. The results show that the most stable structures are cuboctahedron （COh） for Ag13 and icosahedron （Ih） for CUl3, Agl2CUlcore, and Cul2Aglsur. In the visible-near infrared optical absorption, the transitions consist of the interband and the intraband transitions. Moreover, red shifts are observed as follows： 1） clusters change from Agl2CUlcore to Ag13 to Ag12Culsur with the same motifs, 2） the shapes of pure Agl3 and Agl2CUlcore clusters change from COh to Ih to decahe- dron （Dh）, 3） the shape of Agl2CUlsur clusters changes from Ih to COh to Dh, and 4） the shapes of pure CU13 and Cu12Agl clusters change from Ih to Dh to COb. All of the Raman and vibrational spectra exhibit many significant vibrational modes related to the shapes and the compositions of the clusters. The ranges of vibrational spectra of Ag13, Agl2CUl or CU13, and Cu12Agl clusters become narrower and the vibrational intensities increase as the shape of the clusters changes from Ih to Dh to COh.     

Stress-induced polymer deformation in shear flows

By means of dynamic Monte Carlo simulation of bulk lattice polymers in Couette shear flow, it was demonstrated that in addition to velocity gradient the constant driving forces acting as the activation aspect of shear stresses can also raise polymer deformation. Moreover, enhancing driving forces in a flow without any velocity gradient can reproduce nonNewtonian fluid behaviors of long-chain polymers. The simulations of Poiseuille shear flow with a gradient of shear stresses show that, the velocity gradient dominates small deformation in the flow layers of low shear stresses, while the shear stress dominates large deformation in the flow layers of high shear stresses. This result implies that the stress-induced deformation could be mainly responsible for the occurrence of non-Newtonian fluid behaviors of real polymers at high shear rates.     

Extensional flow of bulk polymers studied by dynamic Monte Carlo simulations

Dynamic Monte Carlo simulations of bulk lattice polymers driven through planar geometries with sequentially converging,parallel and diverging spaces between two neutrally repulsive solid plates are reported.The spatial profiles of polymer velocity and deformation along the course of such a laminar extensional flow have been carefully analyzed.The results appear consistent with experimental observations in literature.In the entrance and exit regions,a linear dependence of chain extension upon the excess velocity has been observed.Moreover,an annexed shear flow and a molecular-dispersion effect are found.The results demonstrate a useful strategy of this approach to study polymer flows and bring new insights into the non-Newtonian-fluid behaviors of bulk polymers in capillary rheometers and micro-fluidic devices.     

用于重离子治癌回旋引出的实时流强测量系统北大核心CSCD

为满足重离子治癌加速器装置(HIMM)回旋加速器引出段束流流强的测量需求,设计了新的束流流强测量系统,该系统利用积分电流变换器(ICT)及锁相放大器等配套电子学,能够实现束流流强的非拦截实时测量。文中首先分析了中能束线(MEBT)束流流强的测量需求,并对设计方案进行了实验室系统分析和在线束流强测量。实验室结果表明,锁相放大器的幅度和相位响应一致性满足测量需求。由于ICT对束流流强的测量是相对测量,先使用法拉第筒对ICT进行在线标定;标定前先对法拉第筒(FC)(20μA档位)和ICT系统的流强分辨在线测量,分别为6.45 nA和5.163 nA。由于束流抖动的影响,测量的束流的稳定性约90 nA,其对应的相对测量误差约8%,ICT系统响应时间小于1 ms。测量结果表明,该系统满足物理测量需求。回旋加速器高频系统参数变化引起ICT标定系数变化的工作将在进一步工作中展开。     

维多利亚蓝B与DNA作用的共振光谱特性及分析应用

文章基于维多利亚蓝B与脱氧核糖核酸在弱碱性条件下共振光散射的增强效应。建立了一种测定DNA的共振光散射法。pH值在 9 0～ 10 5范围内 ,三羟甲基氨基甲烷和盐酸 (Tris HCl)缓冲溶液中 ,维多利亚蓝B与DNA分子作用 ,使共振光散射增强 ,存在二个共振光散射增强峰 ,其强度与DNA的浓度呈线性关系 ,线性范围为 0～ 3 0mg·L- 1 ,相关系数为 0 9978,检出限为 2 1 5 μg·L- 1 ,用于fsDNA合成样品的测定获得了满意的结果     

光子晶体光纤中飞秒激光脉冲传输研究

为更精细地描绘飞秒光脉冲在光子晶体光纤中的传输和演化,用分步傅里叶方法求解广义非线性薛定谔方程(GNSE)的基础上,研究了光纤参量随脉冲峰值频移的变化.模拟了飞秒光脉冲在光子晶体光纤中传输和演化的过程.研究发现：光纤色散和强非线性对飞秒脉冲在光子晶体光纤中传输、演化以及超连续谱的展宽有很大影响.     

TBP-Pd（Ⅱ）-HCl萃取体系微乳的生成及溶液聚集态的谱学研究

采用动态激光光散射(DLS)、Fourier变换红外光谱(FTIR)、核磁共振波谱(31P-/1H NMR)等谱学技术,研究了TBP-Pd(Ⅱ)-HCl萃取有机相中微乳的形成以及溶液聚集态结构的变化。结果表明:(1)伴随钯的萃取,TBP萃取有机相中形成微乳。(2)萃取有机相中酸含量的变化导致溶液结构发生相应改变:胶团聚集体平均流体力学半径随有机相中酸含量的增加先增大而后又减小。微乳"内核水"的O—H伸缩振动吸收谱带逐渐宽化,与邻近的C—H伸缩振动区形成交迭,且有机相含酸量越高,交迭程度越大。水分子O—H—O弯曲变角振动吸收峰形也发生很大变化。TBP的PO伸缩振动明显向低频移动。核磁共振31P化学位移与活泼氢1H化学位移变化行为相反,说明TBP分子与酸和水分子发生缔合,形成RP=O.H 或RP=O.H3O ,并与PdCl42-存在相互作用。(3)有机相形成微乳水团后,由于大量H 的进入,微乳水团中酸浓度表现出明显的"增浓效应"。微乳水池内部微观环境的改变是导致钯萃取行为变化的主要原因。     

基于ZEMAX软件的短焦数字投影镜头的设计

利用ZEMAX光学软件设计了一款适用于部分2.03 cm(0.8英寸)单片DLP投影机机型的短焦(广角)数字投影镜头。该镜头结构由10片透镜组成,具有结构简单、生产成本低、易加工等特点。镜头的全视场角2w达到80,°相对孔径约为1/2.1,有效焦距约为12.7 mm,等效后截距约为37 mm,其投射比约为0.78/1,即1 m的投射距离可以投射出160.02 cm(63英寸)的画面。镜头有较好的成像质量,在分辨率极限35 lp/mm处,0.7视场以内的MTF值均大于0.35,在1/2分辨率极限处大部分视场的MTF值大于0.7,全视场畸变量的绝对值小于3%。