自适应光学随机并行梯度下降算法波前整形规律仿真

本文首先介绍了基于Zernike模式的SPGD算法对大气湍流畸变波前的整形原理,通过推导得到了关于性能指标的简明表达式,使SPGD算法收敛速率得到明显提升。然后建立了自适应光学随机并行梯度下降算法波前整形系统模型,主要对SPGD算法收敛速率、整形能力和整形效果随波前畸变量和变形镜模型的变化规律作了较为详细的仿真研究,整体定性结果表明：三者的变化规律有一定的相似性,同时利用最小二乘法得到了关于整形能力和整形效果变化规律的定量表达式,若从自适应光学波前整形系统的实时性和简单性考虑,在保证一定整形效果的情况下,选择37单元变形镜对畸变波前的3~27（25）阶Zernike像差进行整形即可。     

具有光催化性能的TiO2-SiO2/TiO2两层增透膜的设计与制备

采用膜层设计理论设计了以TiO₂为内层膜,TiO₂-SiO₂复合膜为外层膜的两层增透膜,以钛酸丁酯（TBOT）和正硅酸乙酯（TEOS）作为前驱体,采用溶胶-凝胶法制备了TiO₂溶胶以及SiO₂溶胶,将两种溶胶按比例混合得到了TiO₂-SiO₂复合溶胶,在高硼硅玻璃上镀膜测试。透过率测试结果表明,在波长为550nm处的透过率最高能达到99.4%。在光催化实验中,采用罗丹明B模拟有机污染物,考察了TiO₂对光催化反应的影响。结果表明,在TiO₂存在的情况下,罗丹明B的降解速度大大提高,光催化效率显著增加。     

Preparation and characterization of novel molecularly imprinted polymers based on thiourea receptors for nitrocompounds recognition

Molecularly imprinted polymers (MIPs) for the recognition of nitro derivatives are prepared from three different (thio)urea-bearing functional monomers. The binding capability of the polymers is characterized by a batch binding experiment. The imprinting factors and affinity constants (K) of the imprinted polymers exhibit the same tendency as the binding constants (K_a) of the functional monomers to the target substance in solution. Not only nitrofurantoin is efficiently bound by these MIPs but also a broad spectrum of other nitro compounds is bound with at the intermediate level, addressing that these (thio)urea-based monomers can be utilized to prepare a family of MIPs for various nitro compounds, which can be applied as recognition elements in separation and analytical application.     

随机超载对疲劳裂纹扩展迟滞效应的模拟

考虑超载的迟滞效应,对随机超载作用下的疲劳裂纹扩展进行了模拟计算．载荷谱为在基本恒幅循环载荷基础上加入一以泊松流发生的随机超载序列,超载的大小为均匀分布．采用裂纹闭合模型考虑超载的迟滞效应,认为裂纹张开应力在超载引起的塑性区内按线性规律衰减．循环续循环模拟计算出裂纹从初始长度一直到疲劳破坏的扩展曲线．据此,计算了各种超载发生强度和大小下的疲劳裂纹扩展寿命的平均值与标准差。     

三轴光电跟踪系统对地平式天顶盲区出入点的判定方法

三轴光电跟踪系统可以全方位跟踪空间目标,在地平式光电跟踪系统天顶盲区内通过转动X轴实现快速高精度跟踪。用多种三轴光电跟踪系统对地平式天顶盲区进行判定,包括目标距离信息判定方式、Z轴转动速度判定方法、预置盲区判定方法等。判定方法的选择直接影响三轴光电跟踪系统的跟踪精度。理论分析和仿真表明：以Z轴的最大保精角速度来判定地平式盲区的出入点使三轴系统在天顶附近有更高的跟踪精度,且可实现跟踪方式的平稳过渡。     

Direction-of-arrival estimation using matrix spatial prefiltering approach

An approach to direction-of-arrival （DOA） estimation for multiple narrowband farfield signals is proposed. The technique uses a novel matrix spatial prefiltering approach. Specifically, a matrix filter is designed to spatially filter the incoming data snapshots. The un-wanted components arriving from the stopband angular sectors are attenuated and the desired components from the angular sector of interest pass with minimal distortion. The matrix filter spatially filters the element-space data and the output reserves the element-space data property, which makes it very useful by passing sensor data through a spatial prefilter prior to applying many other array processors to attenuate interferences and improve system performance. Several examples of DOA estimation problem are presented to illustrate the performance of the proposed spatial prefiltering approach. Results of simulation and real data show that the pre-filter can efficiently attenuate the spatial interferences and significantly improve the estimation and resolution capability of DOA estimators at low signal-to-noise ratios for the sources located inside the passband sector. In addition, the use of spatial prefilter makes it possible to estimate DOAs for multiple sources more than the number of the elements of an array.     

聚乙烯亚胺对人血清白蛋白的构象和结合能力的影响

为了解基因载体材料聚乙烯亚胺（PEI）细胞毒性的分子作用机理,本文应用吸收光谱、荧光光谱、圆二色谱、动态光散射和zeta-电位测定分析平均相对分子量为1.8和25 kDa的PEI（记为PEI1.8k和PEI25k）对人血清白蛋白（HSA）构象的影响,同时以8-苯氨基萘-1-磺酸镁（ANS）和槲皮素为模型化合物,了解PEI对HSA结合能力的影响及机理。结果发现,PEI与HSA结合形成静态复合物,导致HSA流体动力学直径变小和分子内环境疏水性增强。PEI1.8k和低浓度的PEI25k引起HSA的a-螺旋结构增加,但是高浓度的PEI25k对HSA二级结构具有稳定作用。PEI对HSA结合能力的影响主要归因于PEI的竞争结合和PEI与HSA结合引起的蛋白质构象变化。PEI的竞争结合降低了HSA对ANS和槲皮素的结合效率,但是蛋白质的构象变化增强了HSA与ANS和槲皮素的结合能力。PEI与HSA的相互作用具有明显的分子尺寸效应,增加PEI的相对分子量可以增强对HSA构象和结合能力的影响。     

Acetyl-CoA Deficiency Is Involved in the Regulation of Iron Overload on Lipid Metabolism in Apolipoprotein E Knockout Mice

The role of dietary iron supplementation in the development of nonalcoholic fatty liver disease (NAFLD) remains controversial. This study aimed to investigate the effect of excess dietary iron on NAFLD development and the underlying mechanism. Apolipoprotein E knockout mice were fed a chow diet, a high-fat diet (HFD), or an HFD containing 2% carbonyl iron (HFD + Fe) for 16 weeks. The serum and liver samples were acquired for biochemical and histopathological examinations. Isobaric tags for relative and absolute quantitation were performed to identify differentially expressed proteins in different groups. Excess dietary iron alleviated HFD-induced NAFLD, as evidenced by significant decreases in serum/the hepatic accumulation of lipids and the NAFLD scores in HFD + Fe-fed mice compared with those in HFD-fed mice. The hepatic acetyl-CoA level was markedly decreased in the HFD + Fe group compared with that in the HFD group. Important enzymes involved in the source and destination of acetyl-CoA were differentially expressed between the HFD and HFD + Fe groups, including the enzymes associated with cholesterol metabolism, glycolysis, and the tricarboxylic acid cycle. Furthermore, iron overload-induced mitochondrial dysfunction and oxidative stress occurred in mouse liver, as evidenced by decreases in the mitochondrial membrane potential and antioxidant expression. Therefore, iron overload regulates lipid metabolism by leading to an acetyl-CoA shortage that reduces cholesterol biosynthesis and might play a role in NAFLD pathogenesis. Iron overload-induced oxidative stress and mitochondrial dysfunction may impair acetyl-CoA formation from pyruvate and β-oxidation. Our study provides acetyl-CoA as a novel perspective for investigating the pathogenesis of NAFLD.