分类： 物理学 >> 核物理学 提交时间： 2023-06-09
摘要： 考虑到低能电子（LEEs；020 eV）在放射生物学中的重要性，金纳米颗粒（AuNPs）在亚keV电子照射下作为高通量LEEs发射源的放射增敏潜力已经得到提出。在这项研究中，基于介电函数理论开发了一套径迹结构蒙特卡罗模拟程序来模拟50keV以下电子在金材料中的输运。在该程序中，为了更精确地描述二次电子发射中的LEEs发射，针对非弹性散射、弹性散射和电子-声学声子散射理论进行了改进，并进一步地使用二次电子产额和反向散射系数对该程序进行了验证。在该程序中还开发了剂量计算模块，为了确保剂量学的准确性，我们使用了蒙特卡罗工具包Geant4进一步对比验证了能量沉积的计算。该优化后的蒙特卡罗程序的开发为未来对AuNPs在靶向放射性核素治疗中影响的研究奠定了基础。
分类： 农、林、牧、渔 >> 土壤学 提交时间： 2018-02-07 合作期刊: 《干旱区科学》
摘要： Carbon (C) storage has received significant attention for its relevance to agricultural security and climate change. Afforestation can increase C storage in terrestrial ecosystems, and has been recognized as an important measure to offset CO2 emissions. In order to analyze the C benefits of planting wolfberry (Lycium barbarum L.) on the secondary saline lands in arid areas, we conducted a case study on the dynamics of biomass carbon (BC) storage and soil organic carbon (SOC) storage in different-aged wolfberry plantations (4-, 7- and 11-year-old) established on a secondary saline land as well as on the influence of wolfberry plantations on C storage in the plant-soil system in an arid irrigated area (Jingtai County) of Gansu Province, China. The C sequestration and its potential in the wolfberry plantations of Gansu Province were also evaluated. An intact secondary saline land was selected as control. Results show that wolfberry planting could decrease soil salinity, and increase BC, SOC and litter C storage of the secondary saline land significantly, especially in the first 4 years after planting. The aboveground and belowground BC storage values in the intact secondary saline land (control) accounted for only 1.0% and 1.2% of those in the wolfberry plantations, respectively. Compared to the intact secondary saline land, the SOC storage values in the 4-, 7- and 11-year-old wolfberry plantations increased by 36.4%, 37.3% and 43.3%, respectively, and the SOC storage in the wolfberry plantations occupied more than 92% of the ecosystem C storage. The average BC and SOC sequestration rates of the wolfberry plantations for the age group of 0–11 years were 0.73 and 3.30 Mg C/(hm2•a), respectively. There were no significant differences in BC and SOC storage between the 7-year-old and 11-year-old wolfberry plantations, which may be due in part to the large amounts of C offtakes in new branches and fruits. In Gansu Province, the C storage in the wolfberry plantations has reached up to 3.574 Tg in 2013, and the C sequestration potential of the existing wolfberry plantations was 0.134 Tg C/a. These results indicate that wolfberry planting is an ideal agricultural model to restore the degraded saline lands and increase the C sequestration capacity of agricultural lands in arid areas.
点击量
通过
点击量
下载量
评论
