高分辨率405 nm激光显微成像系统研究

 研究了405 nm短波长激光作为照明光源、数值孔径0.65显微物镜组成的显微成像系统。采用该系统对CD-R及DVD-R盘片进行了显微成像,并对激光成像散斑进行了消除,同时利用CCD图像传感技术和图像采集技术对显微图像进行实时观察与存储,与卤素灯白光作为照明光源时的显微图像进行了比较。结果表明：该系统在卤素灯白光作为照明光源时对CD-R盘片信息点可清晰分辨,但对DVD-R盘片信息点的图像不可分辨;而在405 nm激光照明时信息点均可清晰分辨,系统分辨优于400 nm,明显高于普通卤素灯白光照明系统。     

浓度序列对基于双异步正交样品设计构建的二维异步谱峰信噪比的影响

双异步正交样品设计(DAOSD)是通过对样品体系施加浓度的微扰,诱导光谱信号产生动态变化,并通过数学处理研究样品中物质间相互作用的二维相关光谱方法。提高二维谱图的信噪比对于谱图中交叉峰的分辨乃至物质间相互作用的考察有着十分重要的意义。通过计算机模拟考察了DAOSD构建二维相关光谱的方法中样品浓度序列对光谱行为影响。结果表明,在溶液数量较少的情况下,通过改变样品的浓度和组合顺序,可以有效提高交叉峰的信噪比,从而得到更高质量的二维谱图。     

Precise absolute positioning for a single-frequency user

A new strategy to realize precise absolute positioning for a single-frequency user is presented. In the presented strategy, the receiver clock and ambiguities are removed using the satelliteand epoch-differenced (SDED) algorithm. As a further development of the SDED algorithm, a regional augmentation network is used to generate the SDED atmospheric delays at the user. The weakened mathematic property due to the epoch-differenced operation is improved by adding the generated atmospheric delays and applying the robust estimation. To test the new approach, the 24-h data at 5 Continuous Operation Reference Station (CORS) stations in Shanghai is processed. The results show a more than 96% success rate, defined as the case where three directions achieve the desired positioning accuracy of 10 cm, when the observation is longer than 20 min. The 20-min static results show that the new method can reach an accuracy of 3.42, 4.76 and 9.26 cm in the North, East and Up directions, respectively. An experiment was carried out to assess the kinematic positioning. The results show that the kinematic positioning accuracy is 4.11, 5.31 and 4.05 cm in the north-south, east-west and height directions,respectively.     

Chemical synthesis and characterization of manganese oxide coated Ni particles

Nanosized Ni particles with an average diameter of about 8 nm were prepared by reducing of NiCl 2 with sodium borohydride (NaBH 4 ) in aqueous solution. By moderate annealing in protective atmosphere, the composite grew up to be 15-20 nm particles. Both of the as-prepared and annealed Ni particles were coated by a layer of manganese oxide via decomposition reaction in aqueous KMnO4 solution. Hysteresis loops of as-prepared samples show a large increase in the magnetization with decreasing temperature and an unsaturated component at high magnetic field. In contrast, the ferromagnetic characteristics of annealed one are much stronger with large magnetization and coercivity. The thermomagnetic curves verified the coexistence of ferromagnetic Ni and antiferromangetic Mn oxide phases. But there exists no exchange bias behavior in the samples, even though the interface structure between the ferromagnetic Ni core and the antiferromagnetic manganese oxides has been distinctly formed. The absence of exchange bias probably originates from the weak ferromagnetic characteristic of Ni cores.     

探地雷达测定地基土含水量的实验研究

利用室内模型槽,采用探地雷达开展了测定地基土含水量的室内实验研究。通过对探地雷达反射波法测定的介电常数和烘干法测定的含水量之间的曲线拟合,提出了实验用粉土的含水量与介电常数之间的经验公式。与实测含水量的对比分析表明,Topp公式在一定含水量范围内有良好的适用性,而本文提出的经验公式较Topp公式具有更宽的含水量适用范围和更高的预测精度;针对不同类型土建立相应的含水量和介电常数之间的经验公式是必要的,将有助于提高探地雷达测定地基土含水量的精度。     

兰州放射性核束流线 *

描述了兰州重离子加速器国家实验室最近建成并已投入运行的新装置———兰州放射性核束流线 (RIBLL) .RIBLL是PF型双消色差反对称结构放射性核束分析设备 ,它的立体角接收度≥ 6 .5msr,动量接受度± 5 % ,最大磁刚度4.2Tm ,元素分辨>150 ,质量分辨>300 ,最短分辨时间 <1μs.初级束流的入射角在 0°～ 5°范围可调 .RIBLL已为第一批物理实验提供¹⁷N ,⁸He等多种放射性核束流 .     

ISOVALEROYL OXOKADSURANE,A NOVEL DIBENZOCYCLOOCTADIENE LIGNAN POSSESSING A SPIROBENZOPURANOID SKELETON

Isovaleroyl oxokadsurane, a novel dibenzocyclooctadiene lignan pos-sessing a spirobenzofuranoid skeleton was isolated from the stems of Kadsura coccinea.Its structure and relative configuration were determined by X-ray diffraction analysis.     

电荷耦合器件的γ辐照剂量率效应研究

对电荷耦合器件进行了不同剂量率的γ辐照实验,通过多种参数的测试探讨了剂量率与电荷耦合器件性能退化的关系,并对损伤的物理机理进行分析。辐照和退火结果表明:暗信号和暗信号非均匀性是γ辐照的敏感参数,电荷转移效率和饱和输出电压随剂量累积有缓慢下降的趋势;暗场像素灰度值整体抬升,像元之间的差异显著增加;电荷耦合器件的暗信号增量与剂量率呈负相关性,器件存在潜在的低剂量率损伤增强效应。分析认为,剂量率效应是由界面态和氧化物陷阱电荷竞争导致的。通过电子-空穴对复合模型、质子输运模型和界面态形成对机理进行了解释。     

有机薄膜电致发光失效过程的多重分形谱研究

用多重分形谱描述了荧光显微镜原位观察到的有机薄膜电致发光的失效过程.实验观察表明：有机层/金属电极界面上气泡的产生是电致发光的失效的原因.多重分形谱的分析显示：随薄膜工作时间愈长或工作电压愈高,分形谱的宽度愈窄,表明气泡的数量逐渐增加并愈加均匀地分布在界面上,这一结果和实验观察完全一致,因此多重分形谱可以很好地描述这种失效过程.