类氦离子(Z=3～16)的光谱数据及Mg的高阶离化势的多组态相对论计算

根据相对论多组态理论 ,采用“多功能相对论原子结构计算程序”GRASP2 ( 1992 ) ,计算了类氦离子 (Z =3- 16)的 1s2 ( 1S0 ) - 1s2 p( 1P1) ,1s2 ( 1S0 ) - 1s3p( 1P1)的跃迁波长、自发跃迁系数、加权振子强度和Mg的各阶电离势 ,其中考虑了电子相关能。计算得到的各值与实验值和文献值进行比较。

类镍钆(Gd^(36+))离子的双电子复合系数研究

在自旋轨道劈裂阵模型下 ,通过类铜组态理论计算出类镍 Gd3 6+ 的双电子复合速率系数 ,得出其在电子温度 0 .0 2～ 5 .0 0 ke V范围内的变化规律 ,影响双电子复合速率系数的主要因素是相应的自电离系数和离化势。

In-situ measurement of CO2 at the Xinglong regional background station over North China

High-accuracy continuous measurements of atmospheric concentrations of CO2 were made from May 2016 to December 2017 using the Picarro G2301 analyzer at Xinglong station(40°24′N,117°30′E,940 MSL),150 km northeast of Beijing.The near-ground CO2 measurements were calibrated by standards based on WMO procedures.The regional background measurements were ltered by the robust extraction of baseline signal method to study the seasonal and diurnal cycles.The regional background CO2 concentrations were low in summer.The maximum diffierence between the local sources and regional background CO2 concentrations occurred in summer and autumn,indicating a strong in uence from local sources.Cluster analysis and potential source contribution function analysis showed that the long-distance transport of anthropogenic emissions in the Beijing Tianjin Hebei metropolitan area in uenced the CO2 concentrations in Xinglong,espe-cially in summer.The diurnal variation of CO2 was mainly in uenced by the various vertical transport conditions of the tropospheric atmosphere in a day.

Effects of Heavy-ion Beams Irradiation on Survival Rate and Antioxidant Enzymes of Sweet Sorghum Seedlings

[Objective] This study aimed to investigate the effects of heavy-ion beams irradiation on the seed germination potential, survival rate, antioxidant enzyme activi- ties and lipid peroxidation of sweet sorghum. [Method] The dry seeds were irradiated by ＇2（36. heavy ion beams with absorbed doses： 0, 40, 80, 120, 160 and 200 Gy, respectively. Then, the seed germination potential, survival rate, antioxidant enzyme activities and lipid peroxidation of sweet sorghum were measured. [Result] Heavy-ion beams irradiation exhibited different influence on germination potential and survival rates. Germination rate showed a downward trend, but the corresponding survival curve of seedlings was saddle-shaped. The activities of SOD, POD, CAT and ASA- POD changed in different trends as well. The MDA content rose toward increasing irradiation dose, suggesting that high dose of heavy-ion beams irradiation enhanced the damage to membrane of sweet sorghum seedlings. [Conclusion] After being irra- diated, germination potential and survival rates of sweet sorghum were decreased, and antioxidant enzymes activity changed greatly. This study laid the basis for fur- ther work on breeding and improvement of sweet sorghum irradiated by ,^（12）C^（6＋） heavy ion beams.

Ozonation of Sulfur Dioxide in Sulphuric Acid Solution

In this study, the oxidation rates of sulfur dioxide （SO2） in sulphuric acid solution by ozone and oxygen were compared, and the oxidation mechanism of ozone on SO2 was investigated. The results showed that the oxidation-reduction potential of the acidic solution was enhanced, the transformation rate of sulfuric acid to sulphuric acid was increased and the absorption driving force was improved in the presence of ozone. By comparing the amount of sulfate ions measured in the experiments and the theoretical amount of sulfate ions calculated from the amount of ozone consumed in the reaction, it can be confirmed that oxygen free radicals from dissociation of ozone are reactive as an efficient oxidant and oxygen from ozone generator participates in the reaction with SO2. 0.602 mol of effective oxygen was introduced into the reaction by one mole of ozone in 10.15 rain at sulphuric acid concentration of 3% （by mass）, SO2 concentration of 1.33% （by volume） and oxygen flow rate of 1.5 L.min^-1 from ozone generator.

Realization of Spin Switch in a Triple-Terminal Double-Quantum-Dot Structure

Electron transport through a triple-terminal double-quantum-dot structure is theoretically studied. By adjusting the chemical potential in leads, two channels in this system are created, and in the presence of magnetic flux the conductances for the two channels present remarkable difference from each other. When the quantum dots are made of ferromagnetic materials, the levels of quantum dots are spin dependent, then spin polarization comes about in the two channels. Furthermore, in some regions spin polarization in the different channels are opposite. We consider that this model can be a device prototype for spin filtering and spin separation.

A User Participation Behavior Prediction Model of Social Hotspots Based on Influence and Markov Random Field

Hotspot topic trends can be captured by analyzing user attributes and historical behavior in social network. In this paper, we propose a user participation behavior prediction model for social hotspots, based on user behavior and relationship data, to predict user participation behavior and topic development trends. Firstly, for the complex factors of user behavior, three dynamic influence factor functions are defined, including individual, peer and community influence. These functions take timeliness into account using a time discretization method. Secondly, to determine laws of individual behavior and group behavior within a social topic, a hotspot user participation behavior prediction model is proposed and associated with the basic concepts of randora field and Markov property in information diffusion. The experimental results show that the model can not only dynamically predict the individual behavior, but also grasp the development trends of topics.

Re-visit N／Z Ratio of Free Nucleons from Collisions of Neutron-Rich Nuclei as a Probe of EoS of Asymmetric Nuclear Matter

The N/Z ratio of free nucleons from collisions of neutron-rich nuclei as a function of their momentum is studied by means of isospin-dependent Quantum Molecular Dynamics. We find that this ratio is not only sensitive to the form of the density dependence of the symmetry potential energy but also its strength determined by the symmetry energy coefficient. The uncertainties about the symmetry energy coefficient influence the accuracy of probing the density dependence of the symmetry energy by means of the N/Z ratio of free nucleons of neutron-rich nuclei.

Mode-specific and bond-selective dissociative chemisorption of CHD_3 and CH_2D_2 on Ni(111) revisited using a new potential energy surface

Dissociative chemisorption of methane on a nickel surface is a prototypical system for studying mode-specific chemistry in gassurface reactions.We recently developed a fifteen-dimensional potential energy surface for this system which has proven to be chemically accurate in reproducing the measured absolute dissociative sticking probabilities of CHD_3in thermal conditions and with vibrational excitation on Ni(111)at high incident energies.Here,using this new potential energy surface,we explored mode specificity and bond selectivity for CHD_3and CH_2D_2dissociative chemisorption at low incidence energies down to^50 k J/mol via a quasi-classical trajectory method.Our calculated dissociation probabilities are consistent with previous theoretical and experimental ones with an average shift in translational energy of^8 k J/mol.Our results very well reproduce the C–H/C–D branching ratio upon the C–H local mode excitation,which can be rationalized by the sudden vector projection model.Quantitatively,however,the calculated dissociative sticking probabilities are systematically larger than experimental ones,due presumably to the artificial zero point energy leakage into reaction coordinate.Further high-dimensional quantum dynamics calculations are necessary for acquiring a chemically accurate description of methane dissociative chemisorption at low incident energies.

TWO-SCALE FINITE ELEMENT GREEN'S FUNCTION APPROXIMATIONS WITH APPLICATIONS TO ELECTROSTATIC POTENTIAL COMPUTATION

In this paper,a two-scale finite element approach is proposed and analyzed for approximationsof Green's function in three-dimensions.This approach is based on a two-scale finite elementspace defined,respectively,on the whole domain with size H and on some subdomain containing singularpoints with size h (h << H).It is shown that this two-scale discretization approach is very efficient.In particular,the two-scale discretization approach is applied to solve Poisson-Boltzmann equationssuccessfully.

Localized States of an Excess Electron in an Ionic Cluster

A theory of an electron affinity for an ionic cluster is proposed both in a quasiclassical approach and with quantization of a polarization electric field in a nanopartiele. A critical size of the cluster regarding in formation of an electron＇s autolocalized state, dependencies of energy and radius of a polaron on a cluster＇s size are obtained by a variational method. It has been found that binding energy of the electron in the cluster depends on a eluster＇s radius but a radius of electron＇s auto-localization does not depend on the cluster＇s radius and it equals to the polaron radius in a corresponding infinity crystal. A bound state of the electron in a cluster is possible only if the duster＇s radius is more than the polaron radius.