UO2 晶体中低密勒指数晶面表面能的分子动力学模拟

采用基于刚性离子势的分子动力学模拟方法初步计算了UO₂晶体中(100), (110)和(111) 3种低密勒指数晶面在300–1500 K范围内的表面能大小. 结果表明, 3种晶面的表面能大小随温度的升高而降低, 与实验结果趋势一致; 原子排列最紧密的(111)晶面具有最低的表面能, 3种晶面的表面能大小从高到低依次为(100), (110)和(111)晶面; 达到平衡状态下的表面层原子相对于体内原子层在表面的法线方向上发生了明显的压缩并且表面层原子的对称性也降低了, 表面原子的弛豫效应一直影响到了第5层. 计算研究结果将有助于深入认识UO₂燃料中裂变气体气泡的聚集长大以及燃料的辐照肿胀开裂行为. 关键词： 分子动力学 2')" href="#">UO₂ 低密勒指数晶面 表面能     

Stark效应的推广

将Stark效应进行推广,得到氢原子所有谱线在稳恒电场中都是三分裂,进而对这一结论进行分析．     

酸性品红共振光散射法测定食品中的锌

建立了测定面制食品中锌的酸性品红共振光散射方法,研究了共振光散射的光谱特征及适宜的反应条件。在pH 6.88的Tris-盐酸缓冲介质及表面活性剂溴代十六烷基吡啶(TPB)存在下,Zn(Ⅱ)能够与酸性品红-TPB结合生成三元复合物,使共振光散射(RLS)显著增强并产生新的共振散射光谱,在最大散射峰379 nm处,体系的共振光散射增强程度(△IRLS)与0.008~0.25 mg·L~(-1)范围内的Zn(Ⅱ)呈线性关系,定量限为0.028 mg/100 g。方法简便、灵敏,加标回收率为98.9%~102%,相对标准偏差(RSD)(n=6)为2.0%~2.2%。方法用于面制食品中Zn的测定,结果满意。     

A modified equation of state for Xe at high pressures by molecular dynamics simulation

The exact equation of state （EOS） for the fission gas Xe is necessary for the accurate prediction of the fission gas behavior in uranium dioxide nuclear fuel, However, the comparison with the experimental data indicates that the applicable pressure ranges of existing EOS for Xe published in the literature cannot cover the overpressure of the rim fission gas bubble at the typical UO2 fuel pellet rim structure. Based on the interatomic potential of Xe, the pressure-volume-temperature data are calculated by the molecular dynamics （MD） simulation. The results indicate that the data of MD simulation with Ross and McMahan＇s potential [M. Ross and A. K. McMahan 1980 Phys. Rev. B 21 1658] are in good agreement with the experimental data. A preferable EOS for Xe is proposed based on the MD simulation. The comparison with the MD simulation data shows that the proposed EOS can be applied at pressures up to 550 MPa and 3 GPa and temperatures 900 K and 1373 K respectively. The applicable pressure range of this EOS is wider than those of the other existing EOS for Xe published in the literature.     

Molecular dynamics simulation of collective behaviour of Xe in UO2

This paper performs atomic simulations of the nucleation and growth of Xe bubble in UO2 at 1600 K.The bubble growth was simulated up to the bubble containing 50 Xe atoms.The Xe atoms were added directly to the bubble one by one,followed by a relaxation of the system for several picoseconds.The simulations estimated the bubble pressure and radius at different Xe concentrations.The results indicate that the bubble pressure drops with the increasing Xe/U and bubble size at low Xe concentration,while the pressure will increase with the Xe/U ratio at high Xe concentration.The swelling of the system associated with the bubble growth was also obtained.Finally,the recovery of the damaged structure was investigated.     

衡阳市体育产业发展存在的问题及对策

对后奥运时期衡阳市体育产业发展现状及存在的问题进行了探讨。研究认为:衡阳市经济发展状况相对落后、政府对体育产业扶持力度不够,体育产业管理经营人才缺乏、核心产业滞后,资源利用率低,发展不平衡,体育市场消费水平偏低。在此基础上提出了如下对策和建议:健全制度,加强体育市场监督管理,健全组织机构,培养体育人才,拓展渠道,发展体育娱乐市场,开发体育旅游产品等。