Thermal stress cleaving of silicon wafer by pulsed Nd：YAG laser

The applied laser energy absorbed in a local area in laser thermal stress cleaving of brittle materials using a controlled fracture technique produces tensile thermal stress that causes the material to separate along the moving direction of the laser beam. The material separation is similar to crack extension, but the fracture growth is controllable. Using heat transfer theory, we establish a three-dimensional （3D） mathematical thermoelastic calculational model containing a pre-existing crack for a two-point pulsed Nd：YAG laser cleaving silicon wafer. The temperature field and thermal stress field in the silicon wafer are obtained by using the finite element method （FEM）. The distribution of the tensile stress and changes in stress intensity factor around the crack tip are analyzed during the pulse duration. Meanwhile, the mechanism of crack propagation is investigated by analyzing the development of the thermal stress field during the cleaving process.     

低温冰箱冷冻对人体组织拉曼光谱的影响

研究了低温冰箱冷冻保存时间对人体甲状腺组织、子宫肌瘤组织的拉曼光谱的影响。组织用磷酸缓冲生理液浸泡 ,于 - 4℃保存 (未冻 ) 1 0 h,测试拉曼光谱 ;测后将组织样品浸入磷酸缓冲生理液 ,置于低温冰箱 - 30℃保存。分别于冷冻几天、十几天和六十天后 ,取出解冻测试拉曼光谱。结果表明 ,冷冻保存 1 0天内对组织的拉曼光谱没有明显的影响。该结果对拉曼光谱研究人体组织具有指导意义     

烧结温度对La0.1Sr0.9TiO3陶瓷热电性能的影响

利用传统固相反应方法, 分别在1440℃, 1460℃, 1480℃和1500℃烧结条件下, 制备了钙钛矿结构的La_0.1Sr_0.9TiO₃陶瓷样品. 样品的粉末X射线衍射结果显示, 不同烧结温度的La_0.1Sr_0.9TiO₃ 陶瓷样品均为单相的正交结构. 从样品的扫描电子显微照片来看, 随着烧结温度的增加, 平均晶粒尺寸逐渐增大. 在室温至800℃的测试温区, 测试了样品的电阻率和Seebeck系数, 系统地研究了不同烧结温度对样品热电性能的影响. 结果表明, 样品的电阻率在测试温区内随着测试温度的升高先略微降低, 然后逐渐升高;总体来看, 样品的电阻率随烧结温度的升高先增大后降低. 在测试温区内, Seebeck系数均为负值, 表明样品的载流子为电子; 随着测试温度的升高, Seebeck系数绝对值均有所增大;随烧结温度升高, Seebeck系数绝对值逐渐增大后显著降低. 1480℃制备的样品因其相对较低的电阻率和相对较高的Seebeck系数绝对值, 在165℃时得到最大的功率因子21 μW·K^-2·cm^-1.     

Effects of Laser-Induced Heating on the Photoinduced Birefringence in Azobenzene-Side-Chain Copolymer

The photoinduced birefringence was observed in the polymer poly[2-(4-(4-cyanophenyl) diazenyl phenyloxy) ethoxyl methacrylate] with a cw 532nm laser. The az, obenz, ene polymer character has been studied under the con-ditions of various illuminating time and light intensities. By analysing the processes of reorientation, the egect of laser-induced heating has been introduced to the buildup of photoinduced birefringence in azobenzene-side-chain copolymer. The curves for the buildup of birefringence were fitted with a modified fimction, i.e., biexponential curves and Gaussian curves. The relationship among all the parameters has also been presented. With the modified fitting fimction, we obtain a better fitting result.     

nA量级微电流测试仪的研发

光传感器是利用光敏元件将光信号转换为电信号的传感器，它的敏感波长在可见光波长附近，包括红外线波长和紫外线波长。光传感器不只局限于对光的探测，它还可以作为探测元件组成其它传感器，对许多非电量进行检测，只要将这些非电量转换为光信号的变化即可。光传感器是目前产量最多、应用最广的传感器之一，它在自动控制和非电量电测技术中占有非常重要的地位．     

准一维有机超导体(TMTSF)_2ClO_4的高精度温差电动势研究

测量了准一维有机超导体 (TMTSF) 2 ClO4 单晶a方向不同降温速率下的高精度温差电动势 (6— 2 80K) .高温下的温差电动势表现出线性行为 ,不能被正常的一维电子能带理论所解释 .在 2 4 0K左右观察到温差电动势斜率发生反常突变 .在 14 0K左右温差电动势向下逐渐偏离线性行为 ,这与 1D— 2D的维度渡越相关 .对阴离子有序—无序相变温度Ta(Ta=2 4K)附近的温差电动势结果与比热和电阻率的数据进行了比较 .对于极慢速降温的温差电动势 ,求导后可以看到相变的痕迹 .随着通过Ta 降温速率的增大 ,在Ta 之下的温差电动势数值出现了一个逐渐增大的整体抬高 .对此进行了讨论 .     

铝与L-谷氨酸和α-酮戊二酸相互作用的电位滴定分析

采用电位滴定对酸性溶液中Al-α-酮戊二酸和Al-L-谷氨酸反应体系的形态分布进行了分析，获得如下结论：(1)Al^3 与α-酮戊二酸在酸性溶液中配位形成1：1[AlLH^2 ，AlL^ ，AlLH-1]和1：2[AlL2^-，AlL2H^3--2]的单核形态以及2：1[Al2L^4 ]的双核形态；(2)Al^3 与L-谷氨酸在酸性溶液中配位形成1：1[AlAH^2 ，AlA^ ，AlAH-1]的单核形态以及2：1[Al2A^4 ]的双核形态；(3)Al^3 与L-谷氨酸在酸性溶液中配位能力比α-酮戊二酸要弱，与辅酶NAD^ 相当。同时，Al^3 与α-酮戊二酸的配位能力虽然比Fe^3 ，Cu^2 弱，但要比Ca^2 ，Mg^2 强得多。     

侧链型偶氮聚合物液晶在不同温度条件下的光致取向

在高于和低于玻璃化转变温度 (Tg)的温度范围内 ,研究了聚甲基丙烯酸 ( 6 [4 ( 4 氰基偶氮苯 )苯氧基 ]己酯 ) (Poly( 6 [4 ( 4 cyanophenylazo)phenoxy]hexylmethacrylate) (PM6ABCN) )聚合物膜的光致取向行为 .实验结果表明 ,在温度低于Tg 时 ,实验温度对取向速率没有影响 ;高于Tg 温度时 ,取向的速率随温度升高而变大 ,取向过程的表观活化能为 3 2 76kJ mol.通过对Tg 温度以下的光致取向进行分析 ,对光致取向过程提出了一个新的微相模型 ,微相内的温度能够达到Tg 以上 ,而实验中控制的样品宏观温度不变 ;高于Tg 温度时的光致取向过程受到宏观温度的控制 ,其表观活化能远远小于热致的各向同性相I(Isotropicphase,I)到向列相N(Nematicphase,N)相转变表观活化能 ( 3 40 2kJ mol) ,表明光致取向过程对温度的依赖性较小     

Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS

There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project. The length of the tunnel is about 20 m. The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered by soil for shielding. In order to reduce the dose rate at the exit of the cable ducts, we use the ISIS construction, which is designed with four turnings, as a reference for the tunnel design. The thickness of the shielding is obtained by a simulation with the Monte Carlo Code FLUKA. The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved. This paper provides the basis for the design of the tunnel.     

偶氮苯介晶基元取向方式对其取向稳定性影响

根据取向透射率变化研究了偶氮苯侧链液晶聚合物在不同光照功率条件下的取向,用锥光干涉法表征了侧链介晶基元的取向方向,并研究了升温对取向膜的稳定性影响.实验结果表明介晶基元的取向速度和取向度都随光照时间和光照功率增加而增加;超过一定阈值功率(20 mW/cm2)时,随着光照时间延长薄膜的透射率(取向度)反而降低.高功率光照...