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901.
We present experimental measurements and theory of the diffusely backscattered Mueller matrix patterns that arise from illuminating a turbid medium with a polarized laser beam. Our technique employs polarized light from a He-Ne laser (λ=632.8nm) focused onto the surface of the scattering medium. A surface area of approximately 2×2 cm2 centred on the light input point is imaged through polarization analysis optics onto a CCD camera. The Mueller matrix is reconstructed by 49 intensity measurements with various orientations of polarizer and analyser. The measured Mueller matrix of polystyrene spheres is compared with the theory result of incoherent scattering of light by spheres. It shows that the azimuthal patterns of the Mueller matrix are determined by the symmetry of the turbid media and the shape of scattering particles. The result is further proved by experiments with polystyrene spheres of different concentrations in de-ionized water. 相似文献
902.
JIANG Xiao-Guo LI Cheng-Gang WANG Yuan DAI Wen-Hua XIA Lian-Sheng CHEN Nan YANG Guo-Jun 《中国物理C(英文版)》2006,30(8):784-787
The electron beam measurement system for Dragon-I must work synchronously with the beam production and transportation accurately in order to obtain correct data.The synchronization with about 1ns is important.The output waveform of Blumlein lines in pulsed-power system is of amplitude of about 250kV and 20ns active edge time(following edge).The electron beam will hit the conversion target in about 145ns later steadily and the jitter time is about 1—2ns.The synchronization precision with the same level of the jitter time will be reached if the sharp following edge of waveform is selected to be the time base.The synchronization trigger signal for measurement system can be obtained by the way of differentiating the following edge and the accuracy of about ns can also be reached with suitable circuit parameters.The optical fiber is also adopted to remove the interference on the measurement system from the high voltage system.This kind of burst trigger mode overcomes many disadvantages such as low accuracy, long delay time, large jitter in normal trigger mode and can provide the trigger time accurately.It can meet the need to measure the electron beam parameters at any required time. 相似文献
903.
Exotic Behavior of Elastic Scattering Differential Cross-Sections of Weakly Bound Nucleus 17F at Small Angles 下载免费PDF全文
HAN Jian-Long WANG Qi XIAO Zhi-Gang XU Hu-Shan SUN Zhi-Yu HU Zheng-Guo ZHANG Xue-Yin WANG Hong-Wei MAO Rui-Shi YUAN Xiao-Hua XU Zhi-Guo ZHAO Tie-Cheng 《中国物理C(英文版)》2006,30(11):1058-1061
The differential cross-sections for elastic scattering of 17F and 17O on 208Pb have been measured at Radioactive Ion Beam Line at Lanzhou (RIBLL). The variation of the logarithms of differential cross-sections with the square of scattering angles shows clearly that there exists a turning point in the range of small scattering angles (6°—20°) for 17F having exotic structure, while no turning point was observed in the 17O elastic scattering. The experimental results have been compared with previous data. Systematical analysis on the available data seems to conclude that there is an exotic behavior of elastic scattering differential cross-sections of weakly bound nuclei with halo or skin structure as compared with that of the ordinary nuclei near stable line. Therefore the fact that the turning point of the logarithms of differential cross-sections appears at small angle for weakly bound nuclei could be used as a new probe to investigate the halo and skin phenomenon. 相似文献
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胰岛素瘤相关蛋白1(INSM1)是一类转录调节蛋白,通过其C-端的锌指结构域(氨基酸250-510)来识别序列特异性的DNA分子.INSM1的C-端包含有5个串联的锌指结构域,然而这些结构域的结构及其如何识别DNA的分子机制目前仍不清楚.通过重组构建的质粒pET-32m-INSM1(424-497)表达的蛋白质(氨基酸424-497)包含了最后两个锌指结构域4和5,简称为ZF(4-5).该文详细研究了蛋白质ZF(4-5)的诱导表达条件,得到了较高产率的纯化蛋白.核磁共振(NMR)谱和圆二色谱(CD)揭示了Zn2+对稳定锌指蛋白结构的必要性,以及C2H2-Zn2+结合的组氨酸呈现为δ-异构方式. 相似文献
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909.
以万里长城为代表的古建筑是世界瑰宝,更是中华民族的象征和骄傲.本文提出利用便携式核磁共振(NMR)装置来探测研究这类古建筑的建筑材料,在不对其造成损伤的基础上,发掘其隐含的科学、技术和工程相关的丰富信息.为此,作为第一步,设计了适合于探测这类古建筑的便携式单边NMR探测器组合式磁体.该探测器的磁体结构以semi-Halbach为基础,通过不同磁体模块间的组合得到对应移动探测模式、长距离探测模式和均匀磁场探测模式的磁体结构.随后根据优化结果,设计加工了磁体组件,并采用该磁体进行了流体、长城城砖和现代红砖的NMR实验,实测结果与模拟一致.该组合式磁体的优点在于通过不同磁体模块组合,实现了多种探测方式,适用于探测长城等这类古建筑物需要多种探测模式的科学研究. 相似文献
910.