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基于冷中子谱的紧凑型中子自旋倒相器设计
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作者 李新喜 王燕 +2 位作者 王云 黄朝强 张莹 《中国光学》 EI CAS 2014年第4期600-607,共8页
为节省极化中子散射谱仪传输光路的空间,实现特定冷中子谱的极化中子高效率自旋翻转,使用在空间上自然衰减的前端多层膜极化器静磁场作为中子自旋倒相器的导向磁场,在空间上形成了紧凑型冷中子自旋倒相器设计模型。介绍了实际模型物理... 为节省极化中子散射谱仪传输光路的空间,实现特定冷中子谱的极化中子高效率自旋翻转,使用在空间上自然衰减的前端多层膜极化器静磁场作为中子自旋倒相器的导向磁场,在空间上形成了紧凑型冷中子自旋倒相器设计模型。介绍了实际模型物理参数的计算方法。对前端极化器静磁场在空间上的自然衰减进行了实验测试,根据测试结果及拟使用冷中子波段,针对设计的紧凑型中子自旋倒相器的相关参数进行了优化计算。模拟了极化中子在实际复合磁场中的自旋翻转图像,计算了自旋倒相器的翻转效率。对设计的紧凑型中子自旋倒相器进行了翻转效率物理实验测试,测试结果表明:设计的中子自旋倒相器翻转效率可在99.2%以上,达到了预期设计指标,可用于极化冷中子散射谱仪。 展开更多
关键词 冷中子谱 自旋翻转 紧凑型设计 翻转效率 自旋倒相器
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Effect of Mercury on the Proximate Composition of Maize (Zea mays L,)
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作者 Nathaniel Owusu Boadi Harry Okyere +2 位作者 Mercy Badu John Kenneth Mensah Idah Owusu-Appiah 《Journal of Agricultural Science and Technology(B)》 2013年第7期487-492,共6页
Plants can be exposed to mercury either by direct administration as antifungal agents, mainly to crop plants through seed treatment or foliar spray, or by accident. Mercury poisoning has become a problem of interest o... Plants can be exposed to mercury either by direct administration as antifungal agents, mainly to crop plants through seed treatment or foliar spray, or by accident. Mercury poisoning has become a problem of interest on a global scale. Natural emissions of mercury form two-thirds of the input; man-made releases form about one-third. Significant amounts of mercury may be added to agricultural land with sludge, fertilizers, lime and manures. Total mercury levels were determined in six breeds of quality protein maize using cold vapor atomic absorption spectrometry (CVAAS). The breeds analyzed were Aziga, Abeleehi, Akposoe, Golden Jubilee, Etubi and Obaatanpa. Proximate composition of these breeds was also determined. The objective of this study was therefore to assess the effect of mercury on the proximate composition of quality protein maize. The proximate composition of the maize varieties analyzed showed that the moisture content ranged from 11.57% ± 0.205% to 12.76%± 0.042%, ash from 1.11% ±0.064% to 1.58% ±0.021%, protein, 6.51%± 0.307% to 10.39% ±0.306%, fiber 1.44% ±0.071% to 1.87% ± 0.057%, fat 1.84% ± 0.078% to 2.75% ± 0.092% and carbohydrate 71.77% ± 0.035% to 76.54% ± 0.216%. The total mercury levels in the maize breeds analyzed ranged from 0.0010 + 1.17E-05μg/g to 0.0079 + 1.00E-05μg/g. The mercury levels detected were lower than the WHO limit for mercury in food of 0.5 μg/g in all the maize breeds. The low levels of mercury in the maize samples show they are safe for consumption. 展开更多
关键词 MERCURY TOXICITY MAIZE proximate composition CVAAS
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