Gamma-rays camera is mainly used in image diagnostics of intense pulse radiation sources. The spatial resolution of the camera was measured on a 60Co gamma-rays source with edge method. The spatial ...resolution MTF (modulation transfer function) at the 10% intensity was about
2 lp/mm and the maximal single-noise ratio (SNR) of the camera was found to be about 5:1. In addition, the spatial resolution of the camera was measured with pulse X-rays with 0.3 MeV in average energy and exclusion of effects of secondary electrons from consideration. Accordingly, the spatial
resolution MTF at the 10% intensity was about 5lp/mm, verifying effects of secondary electrons induced by 1.25MeV gamma-rays in the scintillator upon the spatial resolution. Based on our analysis, dispersion sizes of secondary electrons in the scintillator are about 0.4 mm∼0.6 mm. Comparatively,
as indicated by detailed analysis of spatial resolutions of the MCP image intensifier and CCD devices, both have little effect on the camera's spatial resolution and could be well neglected.
Hybrid Buck-Boost converter with switched inductor structure (HBBCSI) is a good topology for obtain the negative output voltage since it has high voltage gain when it compares to the conventional ...Buck-Boost converter. In this study, based on the relationship between the two inductors, the operational principles are analyzed in detail. From the timedomain waveforms of two inductor currents and using the averaging method, the averaged and small signal model of the HBBCSI operating continuous conduction mode (CCM) are derived and analyzed. It is found that, unlike the conventional Buck-Boost converter, the current through the inductor with bigger inductance of the HBBCSI will be maintain a nonzero constant value within a certain interval and this point is the key for establishing its averaged and small signal model. Finally, the PSIM simulation results are presented for confirmation.
For a scintillating-fiber array fast-neutron radiography system, a point-spread- function computing model was introduced, and the simulation code was developed. The results of calculation show that ...fast-neutron radiographs vary with the size of fast neutron sources, the size of fiber cross-section and the imaging geometry. The results suggest that the following qualifications are helpful for a good point spread function: The cross-section of scintillating fibers not greater than 200μm×200μm, the size of neutron source as small as a few millimeters, the distance between the source and the scintillating fiber array greater than 1 m, and inspected samples placed as close as possible to the array. The results give suggestions not only to experiment considerations but also to the estimation of spatial resolution for a specific system.……
Thermal evaporation of Mg in oxygen atmosphere under UHV condition was conducted to fabricate ultrathin MgO film over GaAs(1
0
0) substrate at room temperature (
T
R). Synchrotron Radiation ...Photoemission Spectroscopy (SRPES) results show that very weak interaction and interdiffusion exist between the oxide overlayer and substrate indicating that the reaction between Mg and O
2 is much more active than that between Mg with GaAs. The growth of MgO overlayer may be expected in such a mode that Mg reacts with O
2 in gas phase or near surface to form MgO, followed by the deposition of MgO over GaAs(1
0
0).
The interaction of active Mg metal with GaAs(1
0
0) surface as well as the oxidation of Mg ultrathin film were studied employing synchrotron radiation photoemission (SRPES) technique. Interfacial ...reaction was obviously observed through the energy shifts of Mg2p, Ga3d and As3d levels. The resulted Mg ultrathin film was easily and completely oxidized on exposure of oxygen indicating its polycrystalline nature and high sensitivity to oxygen. A model of Mg/GaAs(1
0
0) interface is proposed and the physical and chemical phenomena during the deposition and oxidation of Mg ultrathin film were discussed.
The dynamics of nuclear reaction in plasma is a fundamental issue in many high energy density researches, such as the astrophysical reactions and the inertial confinement fusion. The effective ...reaction cross-sections and ion stopping power in plasma need to be taken into account to analyze the reactivity. In this research, we have experimentally investigated the from D-D reactions from interactions between deuteron beams and deuterated polystyrene (CD) plasma, driven by two laser pulses respectively. The neutron yields, plasma density and deuteron energy loss in plasma have been measured, and the plasma temperature and deuteron stopping power have been analyzed from simulations. It is shown that, compared with a cold target, the reaction probability in plasma conditions can be enhanced or suppressed, which is ascribed to the deuteron stopping power modifications in plasma. In hotter CD plasma, the energy loss of moderate energetic deuterons reduces, which leads to higher D-D reaction probability, while the contrary happens in colder plasma. This work provides new understanding of fusion reactions in plasma environment.
The molecular orientation of perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) multilayers adsorbed on Au (111) surface has been investigated using angular dependent O K-edge near edge X-ray ...absorption fine structure (NEXAFS) spectroscopy. The significant angular dependence of important resonant structures (π* and σ*) reveals that PTCDA molecules adopt an ordered geometry on the substrate surface. The average tilt angle of the PTCDA molecular planes is 27°±10° from the Au (111) surface.
The nanocrystalline FeMoSiB alloys with different grain sizes were prepared during the crystallization of their amorphous solids. The ultimate tensile strength (UTS) and fatigue strength of amorphous ...and nanocrystalline materials were measured and compared with each other. It is found that the ratio of fatigue limit over UTS of amorphous materials reaches the minimum and the maximum fatigue limit can be obtained in one of these nanocrystalline materials. Abnormal Hall-Petch relation was also observed in these nanocrystalline materials.
Study on genetic diversity of 54 sweet corn inbred lines by SSR markers Huang Jun, South China Agricultural University, Guangzhou (China), College of Agriculture, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources; Feng Faqiang, South China Agricultural University, Guangzhou (China), College of Agriculture, State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources; Wang Qingfeng, South China Agricultural University, Guangzhou (China), Office of Key Laboratory Construction
Hua nan nong ye da xue xue bao,
Jan. 2012, Letnik:
33, Številka:
1
Journal Article
利用SSR标记对54份甜玉米自交系进行了遗传多样性分析，从150对引物中筛选出了56对扩增条带清晰、稳定性好的引物。结果表明：56对引物在54份甜玉米自交系中共检测到155个位点的等位基因变异，平均每对引物检测出的等位基因变异为2.77个，变异范围为2-5个，平均多态性信息含量为0.42，变异范围为0.13-0.71。UPGMA聚类结果表明，可将甜玉米自交系划分为三大类，其划分结果与系谱分析基本一致。
The technique of SSR markers was used to study the genetic diversity of the sweet corn inbred lines, 56 pairs of primers selected from 150 pairs of primers. A total of 155 polymorphic bands, an average of 2.77 alleles per primer, variation of 2-5 alleles for each primer, mean polymorphic information content of 0.42 and its range from 0.13 to 0.71 were detected. Clustering analysis in UPGMA classified the sweet corn inbred lines into 3 groups, which were similar to germplasmic genealogy.
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