针对K荧光具有稳定性高、剂量率大、可控性好等优点,设计一套K荧光X射线辐射装置,为核辐射探测器在低能区能量响应呈现出非线性变化趋势提供计量保障。梯形结构设计缩短光束路径,同时有效降低散射干扰;提出以K吸收缘介于辐射体Kα和Kβ...针对K荧光具有稳定性高、剂量率大、可控性好等优点,设计一套K荧光X射线辐射装置,为核辐射探测器在低能区能量响应呈现出非线性变化趋势提供计量保障。梯形结构设计缩短光束路径,同时有效降低散射干扰;提出以K吸收缘介于辐射体Kα和Kβ线之间的材料为次级过滤器,消除L线并减小Kβ相对于Kα线的强度得到参考辐射场。通过蒙特卡罗程序模拟,结果表明:在8.64~98.4 ke V能量范围内,可以找到相应的K吸收缘获取纯度较高的单能荧光参考辐射场。展开更多
Ectomycorrhizal fungus Laccaria bicolor S238N,isolated from a forest soil in central France in 1990s,has demonstrated unequivocally and ability to promote pine growth.In the present nursery bed experiment,the ability ...Ectomycorrhizal fungus Laccaria bicolor S238N,isolated from a forest soil in central France in 1990s,has demonstrated unequivocally and ability to promote pine growth.In the present nursery bed experiment,the ability of this ectomycorrhizal fungus to increase growth and P and K uptake of Douglas Fir seedlings (Zone 22) was examined.Growth of inoculated seedlings was over twice(plant height) and three times (biomass)that of non-inoculated ones.Similarly,both the concentrations and the amounts of P and K uptake by seedlings were significantly increased by fungal inoculation,indicating the improvement of P and K nutrition in mycorrhizal seedlings.In contrast,Al-P in the soils was decreased obviously by plants,especially by mycorrhizas,suggesting utilization of this soil P pool by plants and more efficient Al-P mobilization by mycorrhizas than by nomycorrhizas.Moreover,K extracted by 1mol/L HCl following consecutive extraction of H2O and CH3COONH4,which may not be plant available,could be utilized by fungus colonied roots.This could be explained by the release of protons and oxalate by hypae which leads to replacement of interlayer K in nonexpanded 2:1 clay minerals and bio-weathering of phyllosilicates.展开更多
文摘针对K荧光具有稳定性高、剂量率大、可控性好等优点,设计一套K荧光X射线辐射装置,为核辐射探测器在低能区能量响应呈现出非线性变化趋势提供计量保障。梯形结构设计缩短光束路径,同时有效降低散射干扰;提出以K吸收缘介于辐射体Kα和Kβ线之间的材料为次级过滤器,消除L线并减小Kβ相对于Kα线的强度得到参考辐射场。通过蒙特卡罗程序模拟,结果表明:在8.64~98.4 ke V能量范围内,可以找到相应的K吸收缘获取纯度较高的单能荧光参考辐射场。
文摘Ectomycorrhizal fungus Laccaria bicolor S238N,isolated from a forest soil in central France in 1990s,has demonstrated unequivocally and ability to promote pine growth.In the present nursery bed experiment,the ability of this ectomycorrhizal fungus to increase growth and P and K uptake of Douglas Fir seedlings (Zone 22) was examined.Growth of inoculated seedlings was over twice(plant height) and three times (biomass)that of non-inoculated ones.Similarly,both the concentrations and the amounts of P and K uptake by seedlings were significantly increased by fungal inoculation,indicating the improvement of P and K nutrition in mycorrhizal seedlings.In contrast,Al-P in the soils was decreased obviously by plants,especially by mycorrhizas,suggesting utilization of this soil P pool by plants and more efficient Al-P mobilization by mycorrhizas than by nomycorrhizas.Moreover,K extracted by 1mol/L HCl following consecutive extraction of H2O and CH3COONH4,which may not be plant available,could be utilized by fungus colonied roots.This could be explained by the release of protons and oxalate by hypae which leads to replacement of interlayer K in nonexpanded 2:1 clay minerals and bio-weathering of phyllosilicates.
