硒蛋白S的生物学功能

硒蛋白S是一种新发现的内质网和细胞膜驻留硒蛋白。以往的研究结果揭示硒蛋白S可以保护细胞拮抗氧化损伤及内质网应激诱导的细胞凋亡;参与脂蛋白代谢、精子发育过程、炎症反应及将错误折叠蛋白从内质网腔逆向转移到细胞质中然后降解的过程(即内质网相关蛋白降解)。硒蛋白S基因多态性与糖尿病、冠状动脉心脏病或先兆子痫等疾病密切相关。本文结合本课题组的工作对硒蛋白S的最新研究进展,尤其是硒蛋白S功能的研究成果作了较为详细的介绍,并对未来的研究方向作了展望。     

基于裂纹诱导弦挠度的梁开闭裂纹损伤识别

考虑裂纹缝隙效应,建立了Euler-Bernoulli梁中开闭裂纹位置、深度和初始张开角等损伤参数的识别方法．首先,基于梁中开闭裂纹的等效单向扭转弹簧模型,给出了开闭裂纹Euler-Bernoulli梁静力弯曲挠度的显式闭合解．在此基础上,证明了裂纹诱导弦挠度函数由分段三次多项式组成,并基于其构造特征,建立了基于测量挠度的梁中开闭裂纹位置、裂纹等效扭转弹簧柔度、裂纹初始张开角和裂纹上下侧属性等参数的数值识别方法．最后,通过数值实验考察了挠度测量误差和裂纹位置等对裂纹识别结果的影响,结果表明：裂纹位置、裂纹等效扭转弹簧柔度和裂纹初始张开角等的识别误差随挠度测量误差增大而增大,但裂纹识别结果具有较强的鲁棒性,在工程实际中具有一定的应用前景．     

氧化锆口腔种植体的动态植入过程分析与设计

在牙科种植领域常使用的种植体材料多为纯钛或钛合金, 然而钛金属种植体存在美学缺陷及潜在的致敏可能等问题. 氧化锆陶瓷由于其高强度、美观性与生物相容性被认为是钛金属种植体的理想替代品, 但目前国内对于氧化锆种植体的研究仍处于起步阶段. 本文通过对氧化锆种植体及骨组织进行有限元建模, 并对种植体的动态植入过程进行仿真, 分析了骨组织内部的应力-应变状况. 结果发现, 随着植入深度的增加, 种植体与骨组织的接触面积增大, 松质骨内应力增加. 考虑到骨组织的具体结构, 将松质骨内的最大应力-应变作为分析的主要对象, 结合损伤分析, 对种植体模型进行了优化. 此外, 还设计了3种具有自攻刃设计的种植体模型, 分别进行应力应变分析后确定了最优设计. 之后建立了具有自攻刃设计的种植体模型, 并模拟了临床的3种植入方案: 螺纹成形、螺纹切割、螺纹成形与切割进行分析, 通过分析得到螺纹成形与切割种植方案更为安全的结论. 本文结果可以指导氧化锆种植体的结构设计以及植入时的条件设定等, 为我国自主研发的氧化锆种植体进行了理论指导, 为其早日进行临床应用指明了方向.      

无人机空中光轴基准安装误差及磁偏差测量方法研究

测定飞机与目标定位有关的机载设备的安装误差、磁偏角等固定误差,是无人机实际目标定位前必做的一项工作.现有测定、校正方法繁琐且实用性差.给出一种不同于现有工序,在无人机空中实际目标定位前,在空中利用飞行器本身光电平台的光轴作为基准,对预先测定好经纬度的地面目标进行定位,反向推算来测量出飞机的固定安装误差及磁偏角,再进行校...     

Effect of fuel injection location on a plasma jet assisted combustion with a backward-facing step

Non-reacting and reacting experiments on the ignition by a plasma jet (PJ) torch were performed to understand the correlation between fuel injection location and combustion characteristics in unheated Mach 2 airflow. Fuel was injected through three sonic injectors in the recirculation region behind a backward-facing step: a parallel injector at 2 mm from the bottom wall and two normal injectors at 2 and 9 mm from the step wall. In order to mitigate the combustion pressure interaction with nozzle, an isolator was installed between the nozzle and combustor. The combustion performance of normal injection was little affected by the difference of fuel injection locations. Moreover, normally injected fuel was escaped not to be held in the recirculation region despite of low fuel injection rates. This led to lower combustion performance relative to the parallel injection which provided fuel not to leave the recirculation region. In this case, the role of the recirculation region was to fully hold fuel, and the PJ torch provided hot gases as a heat source and acted as a flame-holder to ignite fuel–air mixtures. In a low temperature inflow condition, combustible regions were constrained around the bottom wall where embedded with the PJ torch. When thermal choking occurred in the combustor, it induced shock train both in the combustor and isolator. Under this unstable condition, the combustion performance of the normal injection was lower than that of the parallel injection. This is because the normal injection led most fuel into low temperature incoming air-stream.     

TiO2/Al2O3薄膜的原子层沉积和光学性能分析

采用原子层沉积技术在熔石英和BK7玻璃基片上镀制了TiO2/Al2O3薄膜,沉积温度分别为110℃和280℃。利用X射线粉末衍射仪对膜层微观结构进行了分析研究,并在激光损伤平台上进行了抗激光损伤阈值测量。采用Nomarski微分干涉差显微镜和原子力显微镜对激光损伤后的形貌进行了观察分析。结果表明,采用原子层沉积技术镀制的TiO2/Al2O3增透膜的厚度均匀性较好,Φ50 mm样品的膜层厚度均匀性优于99%;光谱增透效果显著,在1 064 nm处的透过率〉99.8%;在熔石英和BK7基片上,TiO2/Al2O3薄膜在110℃时的激光损伤阈值分别为（6.73±0.47）J/cm2和（6.5±0.46）J/cm2,明显高于在280℃时的损伤阈值。     

Radiation damage reveals promising interaction position

High‐resolution structural data of protein inhibitor complexes are the key to rational drug design. Synchrotron radiation allows for atomic resolutions but is frequently accompanied by radiation damage to protein complexes. In this study a human aldose reductase mutant complexed with a bromine‐substituted inhibitor was determined to atomic resolution [Protein Data Bank (PDB) code 3onc ]. Though the radiation dose was moderate, a selective disruption of a bromine–inhibitor bond during the experiment was observed while the protein appears unaffected. A covalent bond to bromine is cleaved and the displaced atom is not scattered throughout the crystal but can most likely be assigned as a bromide to an additional difference electron density peak observed in the structure. The bromide relocates to an adjacent unoccupied site where promising interactions to protein residues stabilize its position. These findings were verified by a second similar structure determined with considerably higher radiation dose (PDB code 3onb ).     

双极线性稳压器电离辐射剂量率效应及其损伤分析

为了对双极线性稳压器在电离辐射环境下损伤变化特征及其剂量率效应进行研究,选择一组器件进行⁶⁰Co γ高低剂量率的辐照和退火试验. 结果表明线性稳压器的输出电压、最大负载电流、线性调整率、压降电压等多个关键参数都有不同程度的蜕变. 且各器件在高低剂量率下的辐照响应略有不同,表现出不同的剂量率效应. 文中通过多种形式的测试结果分析,系统地讨论了各参数变化的原因及其内部各模块对稳压器功能的影响. 结合电离损伤退火特性,探讨了各剂量率效应形成的原因. 这不但对工程应用考核提供了参考,而且为设 关键词： 双极线性稳压器 总剂量效应 剂量率效应 辐射损伤     

惯性及弹塑性效应对延性金属材料层裂损伤的影响

本文以空心球壳模型为基础,在飞片加载条件下,讨论了惯性、弹塑性效应以及初始孔洞大小对材料层裂损伤的影响.分析结果表明,在研究材料层裂损伤问题时,惯性、弹塑性效应以及初始孔洞大小的影响是不能忽略的,特别是初始孔洞大小的影响.同时,鉴于初始孔洞大小的重要影响,本文尝试给出了一个分析初始孔洞尺寸的方法. 关键词： 层裂损伤 惯性 弹塑性效应 初始孔洞     

长脉冲激光对组成CCD图像传感器的MOS光敏单元的硬破坏机理研究

以帧转移型面阵CCD图像传感器为例,采用有限元法研究了波长1.06 μm,脉宽ms量级长脉冲Nd:YAG激光与组成CCD传感器的MOS光敏单元的作用过程及硬破坏机理.建立了长脉冲激光辐照MOS光敏单元的热力耦合模型,模拟了MOS光敏单元的温度分布和应力分布.研究结果表明:在长脉冲激光作用下,由于S层表面径向压应力超过其抗压强度引起MOS光敏单元出现了OS层间分裂,进而受径向、环向和轴向压应力的共同作用下,在光敏单元还未熔融时,层间分裂就扩大至光敏单元的整个OS层间.OS层间完全分裂会使光敏单元发生硬破坏,并造成CCD传感器中激光照射区的单个或一列光敏单元的功能完全失效.文章的研究结果可为CCD图像传感器的激光损伤及防护提供必要的理论依据. 关键词： 长脉冲激光 CCD图像传感器 硬破坏机理 层间分裂