变性的α-lactalbumin诱导DegP形成十二聚体

大肠杆菌热休克蛋白DegP,也称作HtrA或蛋白酶Do,具有分子伴侣和蛋白酶两种活性.缺失DegP会导致大肠杆菌在高温下不能存活.DegP的晶体结构表明,它是由两个紧密折叠的三聚体松散地结合在一起形成的六聚体.作者在分子筛柱层析的实验中发现DegP六聚体与变性的α-laetalbumin共孵育后能全部转变为更大的寡聚体.进一步用负染电镜及单颗粒三维重构方法对该寡聚体进行结构分析,发现它是由4个三聚体组成的具有四面体对称性的十二聚体茏形结构.文章还对DegP十二聚体的结构与功能的关系展开了初步的讨论.     

兔C反应蛋白的二维结晶研究

兔C反应蛋白(CRP)由5个单体组成,是一种典型的急性期蛋白.使用从天然CRP储存液中分离出的、由自然解聚生成的CRP单体,我们在由eggPC、lysoPC和DMPS组成的负电磷脂膜上得到了两种单体晶体.其中的一种MI先前已由本实验室获得,而另一种MII则是首次发现.进一步的电子晶体学分析表明,MII晶体的晶格参数为a=20 6(±0 1) nm、b=16 1(±0 1) nm和γ=90(±1)°,其投影图的分辨率为2 06nm,并具有P2对称性.通过比较两种晶体的排列方式和形成类型,我们认为分离得到的CRP单体可能是已被广泛报道的Modified CRP的主要形式.     

利用二维光子结晶结构提高LED发光效率

日本京都大学和科学技术振兴机构(JST)组成的联合研究小组最近宣布，在发光元件结构中使用二维光子结晶结构可提高发光二极管(LED)的发光效率。与没有光子结晶结构相比，将发光元件内部发出的光线照射到LED发光面法线方向的效率(光导效率)达到了4～5倍。过去，由LED内部发出的光线大多沿发光面方向照射，因为没有出口，就会发热。     

菠菜和黄瓜捕光叶绿素a／b蛋白质复合体的二维结晶

膜蛋白的二维结晶化是蛋白质电子晶体学解析膜蛋白三维结构的基础。我们用ｂａｔｃｈ方法实现了去垢剂溶解的黄瓜和菠菜的捕光叶绿素ａ／ｂ蛋白质复合体的二维结晶，获得了质量良好的二维晶体。文章还讨论了黄瓜、菠菜以及豌豆的ＬＨＣ－Ⅱ二维晶体生长条件的异同，以及影响膜蛋白二维晶生长的某些因素。     

菠菜和黄瓜捕光复合体Ⅱ的二维结晶

菠菜和黄瓜捕光复合体Ⅱ的二维结晶＊张兴１徐伟１，２邢力１娄世庆３赵福洪３匡廷云３黄有国２杨福愉２＊国家自然科学基金资助项目（１中科院北京电镜实验室２中科院生物物理研究所３中科院植物研究所）光系统Ⅱ捕光叶绿素ａ／ｂ复合体（ＬＨＣ－Ⅱ）是高等植物叶绿体类...     

二维相关红外光谱研究溶液中蛋白质的结构

概述了二维相关红外光谱基本原理以及它在研究蛋白质结构变化方面的最新应用，所综述的内容主要包括以下几个方面：(1)二维相关掠角反射红外光谱研究蛋白质分子在样品池上的吸附过程；(2)重点概述二维相关红外光谱在研究温度、酸度等物理变量诱导蛋白质变性及结构变化方面的应用。     

无序结构的二维Voronoi模型

Voronoi网络是仿真无序系统的理想模型。本文提出了二维Voronoi修改型网络的形成方法，这些网络的u2值处于0.0至3.0之间。     

多层媒质中三维平面辐射结构的二维小波分析

使用小波函数对多层介质的三维平面金属微带结构(具有水平方向和垂直方向电流)进行分析,即用二维小波函数模拟未知电流密度,根据不同方向金属板尺度的差异,选择不同分辨尺度的二维小波函数,并与传统矩量法比较．     

二维周期结构色散特性的矢量理论分析

在矢量衍射理论基础上给出了任意斜入射下二维周期结构(网格光栅)的角色散表达式。研究表明，二维周期结构的色散特性分析可以将一维光栅涵盖在其中。并阐述了(m，0)级和(0，n)级衍射波的角色散彼此不相关的独立性原理。     

大功率LED高低温特性

在线测量了从－30至100度InGaN和AlGaInP大功率LED的各参数,拟合了两种LED正向压降、相对光强、波长、谱宽和温度的曲线,分析了两种LED参数变化的原因和这些变化对应用的影响。温度对大功率LED的性能和应用都有很大影响,低温时,应考虑正向压降的增大和波长的蓝移,高温时,应考虑光强的下降和波长的红移     

Characteristics of high power LEDs at high and low temperature

The high power light emitting diodes(LEDs) based on InGaN and AlGaInP individually are tested on line at temperatures from -30 to 100℃.The data are fitted to measure the relationship between temperature and the properties of forward voltage,relative light intensity,wavelength,and spectral bandwidth of two different kinds of LEDs.Why these properties changed and how these changes reflected on applications are also analyzed and compared with each other.The results show that temperature has a great influence on the performance and application of power LEDs.For applications at low temperature,the forward voltage rising and the peak wavelength blue-shifting must be considered;and at high temperature,the relative light intensity decreasing and the peak wavelength red-shifting must be considered.     

Screening of long-wavelength laser at high temperature and high current levels

It is found that electroluminescent mode aging at high-temperature and high-current levels is useful for selecting long-lived InGaAsP 1.3 ?m lasers. Lasers selected by this screening have little change in threshold current or forward voltage through the aging test at an elevated temperature with constant light-output power.     

Silver-indium joints produced at low temperature for high temperature devices

A two-step fluxless bonding process adopted to produce high temperature silver-indium joints (80 wt% silver and 20 wt% indium) at relatively low process temperature of 206/spl deg/C has been developed. After annealing the joint continuously for 26 h at 145/spl deg/C, its melting temperature increases to 765-780/spl deg/C, as confirmed by a de-bonding test. The technique thus developed provides a viable alternative to packaging many high temperature devices running at 350/spl deg/C and above. The bonding quality of the Ag-In joints produced was examined using scanning acoustic microscopy. The joint cross-section was also studied using a scanning electron microscope equipped with an energy dispersive X-ray (EDX) spectroscope to find the local microstructure and composition. The results have shown that the joint is nearly void-free and uniform in thickness ranging from 7.2 to 7.8 /spl mu/m. The annealed sample joint, as determined by EDX, is mainly composed of AgIn/sub 2/, Ag/sub 2/In, and AuIn/sub 2/ grains embedded in an Ag-rich Ag-In alloy matrix. During joint formation, the intermetallic compound AgIn/sub 2/, in particular, prevents the indium layer from oxidation, and therefore, no flux is needed. In addition, low process temperatures help to reduce the thermal stresses developed in the bonded structure due to thermal expansion mismatch. Finally, reliability tests were conducted on three sets of annealed joints using a high temperature oven running continuously at 500/spl deg/C for 10, 100, and 1000 h each. Scanning acoustic microscopy (SAM) images on these samples confirmed that the joints have an excellent survivability in a high temperature environment.     

SiC field-effect devices operating at high temperature

Field-effect devices based on SiC metal-oxide-semiconductor (MOS) structures are attractive for electronic and sensing applications above 250°C. The MOS device operation in chemically corrosive, high-temperature environments places stringent demands on the stability of the insulating dielectric and the constituent interfaces within the structure. The primary mode of oxide breakdown under these conditions is attributed to electron injection from the substrate. The reliability of n-type SiC MOS devices was investigated by monitoring the gate-leakage current as a function of temperature. We find current densities below 17 nA/cm² and 3 nA/cm² at electric field strengths up to 0.6 MV/cm and temperatures of 330°C and 180°C, respectively. These are promising results for high-temperature operation, because the optimum bias point for SiC MOS gas sensors in near midgap, where the field across the oxide is small. Our results are valid for n-type SiC MOS sensors in general and have been observed in both the 4H and 6H polytypes.     

Failure mode analysis of oxide VCSELs in high humidity and high temperature

High-speed fiber-optic transceiver modules using parallel optics require that oxide-confined vertical-cavity surface-emitting lasers (VCSELs) be moisture resistant in a non-hermetic package. We have found that the conventional storage 85/85 (85/spl deg/C/85% relative humidity) test does not adequately characterize oxide VCSELs moisture resistance. We have identified three failure modes in the oxide VCSELs under operating conditions in high humidity. In this paper, we discuss the failure mechanisms including dislocation growth, semiconductor cracks, and aperture surface degradation, all associated with operation under high relative humidity. Understanding of these failure modes has led to more appropriate qualification standards and environmentally robust oxide VCSELs.     

Refractive index dispersion of lightguide glasses at high temperature

The refractive index of pure and GeO2-doped silica glasses was measured at wavelengths from 0.4 ?m to 2.1 ?m, over a temperature range from 20°C to 540°C. Values for the thermal coefficient of the refractive index (about 1.2×10?5/°C at 1.3 ?m) were almost identical for both glasses. The data showed that material dispersion for optical fibres increases with increasing temperature.     

温度对SiO2光子晶体模板中生长InP的影响

制备了人工欧泊SiO2光子晶体模板并运用有机金属化学气相沉积(MOCVD)技术在SiO2光子晶体模板中生长填充了InP晶体.实验研究了不同成核温度(300℃,350℃,400℃)对于生长填充InP的影响.扫描电镜和反射谱分析结果显示,温度对于InP在SiO2光子晶体模板中的生长有重要影响.随着成核温度的升高,InP在SiO2光子晶体模板中的填充率随之降低.     

Fabrication of 3D MEMS toroidal microinductor for high temperature application

Based on Microelectromechanical systems (MEMS) technique and thick photoresist lithography technology, a new toroidal-type inductor for high temperature application has been successfully developed. In the fabrication process, heat-resistant materials are used, alumina as insulator and supporting materials instead of polyimide, heat resistant glass for underlay instead of normal glass, and copper for coil. The maximum inductance is 87 nH at 0.826 GHz and maximum of quality factor (Q-factor) is 4.63 at 0.786 GHz, at room temperature. With simulation of thermal deformation, it shows that the developed toroidal inductor can be suitable for high temperature application, from 300 to 700 °C.     

高功率高效率封离式室温CO分子激光器

CO分子激光器是5微米附近连续输出功率最强的激光器之一,它在大气污染探测、分子光谱研究,以及作为诸如自旋反转喇曼激光器泵浦源等方面可望有广泛的应用前景。 CO分子激光器的增益系数随着工作气体温度升高而迅速降低,因此,CO分子激光器通常是采用液氮冷却放电管,或者使用高速流动工作气体的办法来实现激光振荡,获得高功率输出。无疑,这种工作方式对一切实际应用是不方便的。