一种近白光发射聚合物的合成与发光性能

采用Suzuki偶联反应,将9,9-二辛基芴(DOF)和4,7-二噻吩-2,1,3-苯并噻二唑(DBT)共聚,通过调节聚合物中DBT基团的含量来改变其发光颜色,合成了近白光发射的聚合物PDOF-DBTx。通过测试聚合物的光致发光光谱发现:不同配比下的聚合物的红光和蓝光发射峰的位置都没有变化,只是两个发射峰的相对强度发生了变化,随着DBT含量的增加,聚合物的红光峰强度增强;当PDOF-DBTx中x的值为0.05%时,聚合物的发射最接近白光,其发光的色坐标值为(x=0.40,y=0.32);通过热分析和原子力显微镜观察得出,PDOF-DBTx这类聚合物都具有良好的热稳定性和成膜性。     

Instrumentation of coherent X-ray imaging and the primary experimental results

Coherent X-ray microscopy has advanced towards higher-energy, more brilliant sources over the past decade since its demonstrations, and many advancements have been made towards optimizing this imaging technique. Here we present both the experimental instrument for obtaining diffraction patterns and the primary reconstruction of yeast cell 2D projection. In addition, the characteristics of the existing optics at BL29XUL of SPring-8 Facility and the method of image reconstruction are discussed.     

Experimental Study on Soft X-ray Contact Microscopy for Biological Specimens

Using Hefei Synchrotron radiation as X-ray source and photoresist PMMA as recording medium, soft X-ray contact microscopic imaging experiment on hydrated leaf epidermal cells of a kind of dicotyledon is performed and its latent image is read out by a light microscope. Several main factors degrading the resolution of the image are discussed in detail.     

ESTIMATION OF RELATIVE BLOOD VOLUME IN HEAD AND NECK TUMORS

Introduction: The calculation of relative blood volume in head and neck tumor with MR imaging is anew approach that may provide additional hemodynamic information relevant to both untreated and treated tumors. This hemodynamic information is especially usefu l for the differentiation between viable tumor and post surgical changes or rad iation induced scar, and is also beneficial for tumor staging and tumor biopsy.     

高强声下驻波声流特性的实验研究

利用流动显示的方法研究了高强声驻波管中的声流特付。结果指出,在高强声下(声压级大于160dB),驻波管中的声流特性与一般意义上的驻波声流特性差别很大。对该现象的认识有助于进一步了解高声强下的非线性效应。     

Induced electric fields and plasmonic interactions between a metallic nanotube and a thin metallic film

We have numerically simulated the induced electric fields and the plasmonic interactions of a metallic nanotube near a thin metallic film. Our study shows that the energies and intensities of the plasmon resonances depend strongly on the aspect ratio (the ratio of the inner to outer radius) of the nanotube as well as the separation between the center of the nanotube and the upper surface of the metallic film and the thickness of the film. The enhancement of the induced electric field of this system reaches ...     

Characterization of different-Al-content AlGaN/GaN heterostructures on sapphire

Al x Ga 1-x N/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2DEG-h), its crystal quality and rough surface morphology are poor. 2DEG mobility increases with the Al content up to 26% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2105 cm 2 /V s with a sheet carrier density of n s = 1.10 × 10 13 cm -2 , for a 26% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 274 Ω/□ has also been achieved.     

Dynamic Fracture Toughness and Failure Mechanisms of ZnO Whiskers Secondary Reinforced Composites

Quasi-static and dynamic fracture properties and damage mechanism of glass fiber polymer composites embeaaea with different mass percentages of ZnO whiskers are investigated by using an Instron Testing machine and a Split- Hopkinson pressure bar. According to the experimental results and linear fracture mechanics, the quasi-static fracture toughness Kic and the dynamic fracture toughness Kid under various impact velocities of specimens are obtained. Fracture mechanism is investigated by fractography analysis with a scanning electron microscope. The experimental results show that the mass percentage of ZnOw has little influence on the quasi-static fracture toughness, but a little influence on the dynamic fracture toughness and time of initial fracture point of specimens by the reason of various fracture mechanisms.     

一种基于信息理论的高动态范围图像评价方法

高动态范围图像(high dynamic range image)指的是扩大了景物可分辨的光照范围的图像。在HDRI成像中动态范围是难以量化测量的,必须将对动态范围的计算转化为其它易于计算的像质评价函数。HDRI图像的像质评价和普通图像的像质评价存在着较大不同。比较了几种像质评价的方法后,提出了利用图像的熵作为标准进行高动态范围成像评价的方法。利用一种自然图像的概率模型对图像的熵与成像动态范围之间的关系进行了数值模拟,得到了具有普遍意义上的理想成像动态范围的计算公式,公式指出了对自然景物完善成像所需的最大动态范围;给出了图像熵与动态范围之间的关系。利用这种关系可以经由计算图像的熵来对系统的动态范围特性做出评价。这种评价方法在指导高动态范围成像系统的设计,以及高动态范围成像系统的测试中将发挥重要的作用。     

基于DM642的运动目标实时跟踪监控系统的设计

针对视频监控中的运动目标,引入自主跟踪思想,设计了一种基于DSP的运动目标实时跟踪监控系统。系统以TI公司的DSPTMS320DM642为核心,采用改进的差分算法辅以二值化形态学处理进行运动检测,并通过速度归一化求取云台转动矢量,应用于变速云台系统,实现了对运动目标的自主稳定跟踪。实验证明,系统取得了良好的跟踪效果,保证了目标跟踪的自主性、准确性和实时性。