利用HIRFL高能重离子束的核能材料辐照损伤研究

载能重离子与高能中子在材料中能够产生相似的级联碰撞损伤,加之重离子具有大的离位损伤截面和在材料样品中低的感生放射性,载能重离子束成为模拟先进核能装置内部结构材料辐照损伤的重要手段。HIRFL能区的重离子在结构材料中的射程一般远大于晶粒尺寸,因此能够产生材料体损伤,借助小样品技术可以获得材料力学性能变化（尤其辐照脆化）的有用信息,为探讨材料辐照损伤微结构和宏观力学性能变化的关联提供了重要条件。本文简要介绍了近年来我们基于HIRFL高能离子束开展的聚变堆候选材料辐照损伤的研究,包括低活化钢的辐照脆化行为、氧化物弥散强化（ODS）铁素体钢的结构优化对于抗辐照性能的影响、不同载能粒子辐照条件下铁素体/马氏体钢的辐照肿胀数据的关联,以及高能重离子辐照的钨材料中氢同位素的滞留行为。研究表明,结合特殊的测试技术及数据分析方法,高能重离子可作为核能结构材料辐照损伤研究及评估的有效手段。Because of the similarity in cascade damage structure in materials produced by energetic heavy ions and by fast neutrons, and the high displacement rate and low induced radioactivity of samples by heavy ions, heavy ion beam becomes an important tool to simulate radiation damage by energetic neutrons in materials in advanced nuclear energy systems. The ranges of heavy ions provided by HIRFL (Heavy Ion Research Facility in Lanzhou) are generally much larger than the mean dimensions of grains in alloys candidate to advanced nuclear reactors, and is capable of producing radiation damage in bulk scale. It therefore makes possible the evaluation of change of mechanical properties including the radiation induced embrittlement from the irradiated specimens by using miniaturized specimen techniques. In the present paper, we provide an introduction of our recent studies of radiation damage of materials candidate to future fusion reactors by utilizing heavy ion beams in HIRFL.The studies include issues as follows:ductility loss of RAFM steels causes by high-energy Ne ions, impact of oxide dispersoids on the radiation resistance of ODS ferritic steels, correlation of void swelling of ferritic/martensitic steels under different particle irradiation, and behavior of deuterium retention in tungsten under irradiation with high-energy heavy ions. The results show that high-energy heavy ions can be used as a tool to efficiently investigate or evaluate radiation damage in structure materials if combined with some special test techniques and data analysis.     

Full lattice QCD study of the κ scalar meson

We studied the κ light scalar meson in 2+1 flavor full QCD with sufficiently light u and d quarks. Via lattice simulation we measured the correlators for the κ channel in the “Asqtad” improved staggered fermion formulation. After chiral extrapolation we obtained the mass of the κ meson with 826±119 MeV, which is within recent experimental values of 800-900 MeV. The simulations were carried out with the MILC 2+1 flavor gauge configurations at lattice spacing a ≈ 0.15 fm.     

海南产与市售六种中药材中重金属含量的比较研究

用石墨炉原子吸收光谱法测定了海南产与市售六种中药材中 (益智、槟榔、胡椒、广藿香、丁香及肉豆蔻 )的铜、铅、镉含量 ,用氢化物原子荧光法测定了其中砷、汞含量。通过对海南与市售六种中药材中铜、铅、镉、砷及汞五种重金属元素含量的比较研究 ,说明海南生态环境优良 ,是实现中药材GAP种植 ,生产绿色中药材的最佳环境     

高能Pb离子辐照注碳SiO2的红外谱研究

室温下，先用120keV的C离子注入二氧化硅薄膜样品至剂量2.0×1017、5.0×1017或8.6×1017ions/cm2，再用950MeV的Pb离子分别辐照至剂量5.0×1011、1.0×1012或3.8×1012 ions/cm2，然后测量样品的傅里叶变换红外(FTIR)光谱. 通过分析测量得到的傅里叶变换红外谱，发现Pb离子辐照在注碳SiO₂样品中可引起大量的Si－C和Si (C)－O－C等化学键的形成，大剂量Pb离子辐照可在大剂量注碳的SiO₂中产生分子CO₂. 大量的Si－C键的存在和分子CO₂的形成，预示着高能Pb离子辐照在注碳SiO₂样品中有可能形成了纳米Si团簇和/或SiC晶粒.     

Asymptotics for Random Walks with Dependent Heavy-Tailed Increments

We consider a random walk {S _n} with dependent heavy-tailed increments and negative drift. We study the asymptotics for the tail probability P{sup _n S _n >x} as x. If the increments of {S _n} are independent then the exact asymptotic behavior of P{sup _n S _n >x} is well known. We investigate the case in which the increments are given as a one-sided asymptotically stationary linear process. The tail behavior of sup _n S _n turns out to depend heavily on the coefficients of this linear process.     

水体重金属污染的生态效应与防治对策

水体重金属污染已成为全球性的环境问题，本文主要介绍了水体重金属污染对水生植物、水生动物的致毒作用和人体健康的危害，同时，就水体重金属污染的防治对策作了探讨。水体重金属污染的防治途径主要包括两方面，即：源头控制和工程治理。工程治理的方法主要有物理处理法、化学处理法和生物处理法．其中生物处理法具有较好的应用前景。     

生物吸附剂菹草干粉对Cr(Ⅵ)的吸附性能

开发了高效去除重金属Cr(Ⅵ)污染的生物吸附剂,菹草(Potamogeton crispus)干粉吸附剂,通过单因素分析考察了吸附时间、吸附剂颗粒大小、溶液初始pH值、吸附剂用量、Cr(Ⅵ)初始浓度以及离子强度等对重金属离子Cr(Ⅵ)的吸附性能。 结果表明,对吸附效果影响显著的因素有Cr(Ⅵ)初始浓度、吸附剂颗粒大小、溶液初始pH值和离子强度;其吸附行为符合准二级动力学方程,相关系数为0.9998;菹草对Cr(Ⅵ)的吸附等温线符合Langmuir方程。     

河流沉积物中重金属来源分析方法研究进展

河流沉积物中重金属来源分析方法主要有元素形态分析法、剖面分析法、空间分布法、Pb同位素示踪法、多元统计分析法等.对各种方法的优缺点、适用条件和适用范围进行了对比.介绍了重金属来源分析方法的研究进展.     

Critical phenomena in a disc-percolation model and their application to relativistic heavy ion collisions

By studying the critical phenomena in continuum-percolation of discs, we find a new approach to locate the critical point, i.e. using the inflection point of P∞ as an evaluation of the percolation threshold. The susceptibility, defined as the derivative of P∞, possesses a finite-size scaling property, where the scaling exponent is the reciprocal of v, the critical exponent of the correlation length. A possible application of this approach to the study of the critical phenomena in relativistic heavy ion collisions is discussed. The critical point for deconfinement can be extracted by the inflection point of PQGP -- the probability for the event with QGP formation. The finite-size scaling of its derivative can give the critical exponent v, which is a rare case that can provide an experimental measure of a critical exponent in heavy ion collisions.     

THEORETICAL CALCULATION OF THE RELATIVISTIC SUBCONFIGURATION-AVERAGED TRANSITION ENERGIES

A method for calculating the average energies of relativistic subconfigurations in highly ionized heavy atoms has been developed in the framework of the multiconfigurational Dirac－Fock theory. The method is then used to calculate the average transition energies of the spin-orbit-split 3d－4p transition of Co-like tungsten, the 3d－5f transition of Cu-like tantalum, and the 3d－5f transitions of Cu-like and Zn-like gold samples. The calculated results are in good agreement with those calculated with the relativistic parametric potential method and also with the experimental results.