气相扩散法生长溶菌酶晶体的动态光散射研究

首次采用动态光散射研究了气相扩散法生长溶菌酶晶体 .实验中采用了两种溶解溶菌酶的方法，所得实验结果是有区别的 .这种区别表明了 NaCl对溶菌酶分子间相互作用产生十分重要的影响 .实验结果表明，晶体生长过程中，溶液中溶菌酶始终保持单分子与两分子聚集体的状态，这种状态是生长晶体的基础 .

溶液热历史对蛋白质晶体生长影响的内在原因研究

从溶液中聚集体的角度研究了溶液的热历史改变生长出的蛋白质晶体的数目和尺寸的内在原因.将在281和309 K下保存1 d的两组溶菌酶溶液按不同比例混合,加入沉淀剂生长晶体.随着高温溶液的比例增加,生长出的晶体数目减少,同时溶液中生长基元的尺寸增大.在5周内,采用动态光散射对281,293和309K三种温度下保存的溶菌酶溶液中聚集体的变化情况进行监测,发现溶液中均存在大小不同的两部分聚集体,称之为小聚集体与多聚体.前者的尺寸基本不随保存时间而变化,而后者尺寸随保存时间增加而减小,减小的速度与保存温度有关.多聚体的尺寸经过5周后和小聚集体基本相同.研究结果表明,处于无序聚集阶段的溶液的均一化程度和成核阶段生长基元的尺寸受到了溶液热历史的影响,并最终对晶体的数目产生影响.

微小晶体生长过程的光学诊断实验研究

将光学干涉技术与显微技术相结合，应用计算机技术、图像处理技术发展形成一种实时细观诊断的实验方法——光学细观干涉诊断技术；实时观测了KCl晶体在容积为3mm * 3mm * 4.5mm的生长池内的结晶过程，得到了该过程的晶体的表面形貌、生长速率、以及晶体生长尺寸与时间、浓度与时间的定量的关系，观测到由重力引起的浮力对流现象，它直接影响晶体的生长。实验表明重力对晶体生长形态有很大的影响；生长速率与浓度存在很大的依赖关系。

气相扩散速率对溶菌酶晶体生长的影响

为研究气相扩散速率对溶菌酶晶体生长的影响,特设计了一种可方便调节气相扩散速率的晶体生长样品池,并用动态光散射法对不同气相扩散速率下晶体生长过程进行了研究.实验结果表明,随着气相扩散速率的增加,晶体生长过程中的成核阶段缩短.气相扩散速率通过影响溶菌酶溶液形成过饱和的速率来影响生长出的晶体的数量和大小.

Oscillatory Instability of Rayleigh-Marangoni-Benard Convection in Two-Layer System

The convective instabilities in two or more superposed layers heated from below were studied extensively by many scientists due to several interfacial phenomena in nature and crystal growth application. Most works of them were performed mainly on the instability behaviors induced only by buoyancy force, especially on the oscillatory behavior at onset of convection (see Gershuni et. Al.(1982), Renardy et. Al. (1985,2000), Rasenat et. Al. (1989), and Colinet et. Al.(1994)) . But the unstable situations of multi-layer liquid convection will become more complicated and interesting while considering at the same time the buoyancy effect combined with thermocapillary effect. This is the case in the gravity reduced field or thin liquid layer where the thermocapillary effect is as important as buoyancy effect. The objective of this study was to investigate theoretically the interaction between Rayleigh-Bénard instability and pure Marangoni instability in a two-layer system, and more attention focus on the oscillatory instability both at the onset of convection and with increasing supercriticality. Oscillatory behavious of Rayleigh-Marangoni-Bénard convective instability (R-M-B instability) and flow patterns are presented in the two-layer system of Silicon Oil (10cSt) over Fluorinert (FC70) for a larger various range of two-layer depth ratios (Hr=Hupper/Hdown) from 0.2 to 5.0. Both linear instability analysis and 2D numerical simulation (A=L/H=10) show that the instability of the system depends strongly on the depth ratio of two-layer liquids. The oscillatory instability regime at the onset of R-M-B convection are found theoretically in different regions of layer thickness ratio for different two-layer depth H=12,6,4,3mm. The neutral stability curve of the system displaces to right while we consider the Marangoni effect at the interface in comparison with the Rayleigh-Bénard instability of the system without the Marangoni effect (Ma=0). The numerical results show different regimes of the developing of convection in the two-layer system for different thickness ratios and some differences at the onset of pure Marangoni convection and the onset of Rayleigh-Bénard convections in two-layer liquids. Both traveling wave and standing wave were detected in the oscillatory instability regime due to the competition between Rayleigh-Bénard instability and Marangoni effect. The mechanism of the standing wave formation in the system is presented numerically in this paper. The oscillating standing wave results in the competition of the intermediate Marangoni cell and the Rayleigh convective rolls. In the two-layer system of 47v2 silicone oil over water, a transition form the steady instability to the oscillatory instability of the Rayleigh-Marangoni-Bénard Convection was found numerically above the onset of convection for ε=0.9 and Hr=0.5. We propose that this oscillatory mechanism is possible to explain the experimental observation of Degen et. Al.(1998). Experimental work in comparison with our theoretical findings on the two-layer Rayleigh-Marangoni-Bénard convection with thinner depth for H<6mm will be carried out in the near future, and more attention will be paid to new oscillatory instability regimes possible in the influence of thermocapillary effects on the competition of two-layer liquids

溶菌酶晶体生长过程中的扩散传质问题

采用Mach-Zehnder干涉测量系统与图象处理系统相结合实时观测溶菌酶蛋白质晶体生长过程中的流体动力学现象,对汽相扩散法溶菌酶蛋白质晶体生长过程进行了研究,观测到溶菌酶晶体生长时晶体周围存在的干涉条纹.分析了晶体生长时的重力沉降效应和溶质扩散过程.实验结果表明,该生长过程中的流体物理特征直接影响了生长晶体的晶面.根据实验结果,给出对蛋白质晶体生长过程流体物理现象的讨论。 

Direct observation of adsorption sites of protein impurities and their effects on step advancement of protein crystals

We measured noninvasively step velocities of elementary two-dimensional (2D) islands on {110} faces of tetragonal lysozyme crystals, under various supersaturations, by laser confocal microscopy combined with differential interference contrast microscopy. We studied the correlation between the effects of protein impurities on the growth of elementary steps and their adsorption sites on a crystal surface, using three kinds of proteins: fluorescent-labeled lysozyme (F-lysozyme), covalently bonded dimers of lysozyme (dimer), and a 18 kDa polypeptide (18 kDa). These three protein impurities suppressed the advancement of the steps. However, they exhibited different supersaturation dependencies of the suppression of the step velocities. To clarify the cause of this difference, we observed in situ the adsorption sites of individual molecules of F-lysozyme and fluorescent-labeled dimer (F-dimer) on the crystal surface by single-molecule visualization. We found that F-lysozyme adsorbed preferentially on steps (i.e., kinks), whereas F-dimer adsorbed randomly on terraces. Taking into account the different adsorption sites of F-lysozyme and F-dimer, we could successfully explain the different effects of the impurities on the step velocities. These observations strongly suggest that 18 kDa also adsorbs randomly on terraces. Seikagaku lysozyme exhibited a complex effect that could not alone be explained by the two major impurities (dimer and 18 kDa) present in Seikagaku lysozyme, indicating that trace amounts of other impurities significantly affect the step advancement.

硅生长过程中尖形磁场对流场及提拉速率的影响

通过使用基于非正交网格有限体积法的FLUTRAPP(fluid flow and transport phenomena pro-gram)程序模拟了工业8 in单晶硅提拉法生长过程.数值模拟结果表明,流场及提拉速率在单晶硅生长过程中具有振荡特性,提拉速率的振荡周期大约为2 min.尖形磁场的引入能够抑制坩埚中熔体流动的振荡,减小提拉速率的振幅,从而有利于提高所生长单晶的质量.

用半导体激光器对 Yb3+:LYSO 晶体的高效率激光特性的研究

本文报导了采用半导体激光器泵浦的高效连续可调谐Yb:LYSO激光器的输出特性。LYSO晶体同时具有LSO晶体良好的激光性能和YSO晶体易于生长且成本低廉的优点，实验中我们采用5at%掺杂的Yb:LYSO晶体进行研究，获得了最大输出功率2.84W、输出波长1085nm、光-光转换效率54.5%的高效输出。并且得到了1030-1111nm，一共81nm的波长调谐范围，这是目前我们所知道的从Yb:LYSO激光器获得的最宽的调谐输出。

Effect of PbO on precipitation of laser-induced gold nanoparticles inside silicate glasses

We report on three-dimensional precipitation of Au nanoparticles in gold ions-doped silicate glasses by a femtosecond laser irradiation and further annealing. Experimental results show that PbO addition plays the double roles of inhibiting hole-trapped centers generation and promoting formation and growth of gold nanoparticles. Additionally, glass containing PbO shows an increased non-linear absorption after femtosecond laser irradiation and annealing. The observed phenomena are significant for applications such as fabrications of three-dimensional multi-colored images inside transparent materials and three-dimensional optical memory, and integrated micro-optical switches. (c) 2007 Elsevier B.V. All rights reserved.

大尺寸Ce：Lu1.6Y0.4SiO5闪烁晶体的生长和光谱特性

采用中频感应提拉法生长出尺寸为Ф60mm×110mm的Ce：Lu1.6Y0.4SiO5（LYSO）晶体,与LSO晶体相比,LYSO晶体的优势是提高了晶体质量、降低了熔点和原料成本等.在室温下测试了LYSO晶体的透过光谱、激发光谱和发射光谱,结果表明Y的加入使LSO晶体的吸收边向短波方向偏移.Ce^3＋的4f^1→5d^1跃迁吸收导致紫外区产生三个吸收带.发射光谱具有Ce^3＋典型的双峰特征,经Gaussian多峰值拟合,双峰395nm和418nm归属于Ce1发光中心,而435nm的发光峰与Ce2发光中心有

Luminescence studies of Ce : YAG using vacuum ultraviolet synchrotron radiation

Photoluminescence spectrum of Ce:YAG single crystal was studied employing vacuum ultraviolet (VUV) synchrotron radiation. Intrinsic absorption edge at about 52,000 cm(-1) was observed in the absorption spectrum. From the VUV excitation spectrum, the energy of the highest d-component of 53,191 cm(-1) (188 nm) for the Ce3+ ions in YAG was obtained at 300 K. The disappearance of the third 5d level at 37,735 cm(-1) (265 nm) in absorption and excitation spectra in our samples may be due to the impurity Fe3+ ions absorption. (C) 2006 Elsevier Ltd. All rights reserved.

Nd：（La，Sr）（Al，Ta）O3晶体的生长及光谱性能的研究

应用中频感应提拉法生长了新型的Nd：（La，Sr）（Al，Ta）O3（Nd^3＋：LSAT）晶体。运用电感耦合等离子体原子发射光谱仪（ICPAES）测定Nd^3＋离子在Nd^3＋：LSAT晶体中的分凝系数为0．587。X射线粉末衍射（XRPD）测试结果表明Nd^3＋：LSAT晶体与LSAT晶体同构。研究了不同退火条件对晶体光谱性能的影响。分析了Nd^3＋：LSAT晶体的光谱性能，Nd^3＋：LSAT晶体的荧光寿命为290μs。比较了Nd^3＋：LSAT和Nd^3＋：YAG，Nd^3＋：YVO3等晶体的光谱

V^3＋：YAG晶体的生长、色心与光谱性能研究

采用石墨电阻加热的温梯法生长了V：YAG晶体，晶体的不同部位呈现两种不同的颜色：浅绿色和黄褐色．通过对比分析不同颜色V：YAG晶体的室温吸收光谱，推断出石墨发热体高温下扩散出来的C可以起到还原作用，提高晶体中V^3＋tetra离子的浓度，同时诱导了F心的形成．在1300℃下，对不同颜色的V：YAG晶体进行真空退火处理，发现处于八面体格位中的V^3＋离子在热激发作用下与近邻的四面体格位Al^3＋离子存在置换反应，由此产生一定浓度的四面体格位V^3＋离子．同时，F心在退火过程中被完全消除，释放出来的自由电子被

A comparison between TGT and Cz grown Nd : YAG

Large sized neodymium-doped Y3Al5O12 (Nd:YAG) laser crystals have been grown by temperature gradient technique (TGT) method and compared with Czochralski (Cz) method. The comparison of these two crystal growth methods has been listed. The results showed that the TGT method has many advantages over the Cz method. The concentration distribution of Nd ions in the crystals was determined and the absorption spectra of these crystals have been investigated and compared. The TGT grown highly doped Nd:YAG crystal has a larger absorption FWHM than that of Cz grown Nd:YAG crysral. Highly doped Nd:YAG (similar to 2.8 at. pct) crystals could be obtained by TGT.