ISSN 0253-2778

CN 34-1054/N

2015 Vol. 45, No. 5

Display Method:
Triplet dissociation pathway of carbonyl sulfide at 230 nm
GAO Zhi, SUN Zhongfa, WU Xiangkun, TANG Guoqiang, ZHOU Xiaoguo, LIU Shilin
2015, 45(5): 345-352. doi: 10.3969/j.issn.0253-2778.2015.05.001
Carbonyl sulfide (OCS) was excited and dissociated at ~230 nm, and the CO(XΣ+g,v=0,J=42~65) fragment was detected by using (2+1) resonance-enhanced multiphoton ionization at 229825~230000 nm. From the velocity map image of CO+, the kinetic energy and angular distributions of CO fragments were directly obtained. Besides the dominated channel of S(D)+CO(XΣ+g,v=0), S(3P) atom was also observed in photodissociation of OCS at 230 nm. The branching ratio of the S(3P) channel was about 05%, and slightly increased with the rotational excitation of CO fragment from J=56 to 65. With the aid of the recent high-level potential energy surfaces of the excited electronic states of OCS, the S(3P) formation mechanism was proposed. Once absorbing an ultraviolet photon at ~230 nm, the excited OCS in AA′ state is produced initially, and then dissociates to yield S(3P) atom via spin-orbital coupling to b3A″ state.
An ab initio study for electrochemistry: Superconductor layer FeAs as a novel anode material for lithium ion batteries
ZHANG Meng, TAO Shi, HUANG Weifeng, SONG Li, WU Ziyu, CHU Wangsheng
2015, 45(5): 353-358. doi: 10.3969/j.issn.0253-2778.2015.05.002
A potential application of Fe-based layers (FeAs, FeSe) as a new promising anode material was proposed in the fields of second batteries by systematic first-principles calculations. The calculation results indicate that those conventional superconductor layers, such as FeAs, can deliver a theoretical capacity of 1 044 mAh/g, three times higher than that of the graphite-type anode. Further dynamic investigation suggests that Li/FeAs experiences a conversion reaction forming Li3As and Fe through a two-step reaction in the first cycle. In the following cycles, Li-ion reversibly intercalates into arsenic at 077 V or deintercalates from Li3As at 116 V, which is similar to the lithiation/de-lithiation mechanism of silicon anode materials. Based on their high energy density and good dynamic mechanism, these superconductor layers are thought to be a complex functional electrode candidates for future large-energy batteries systems.
Tuning the fluorescence property of copper nanoclusters
LI Dandan, JIANG Yong, YAO Tao, SUN Zhihu, WEI Shiqiang
2015, 45(5): 359-365. doi: 10.3969/j.issn.0253-2778.2015.05.003
A study on tuning the fluorescence property of Cu nanoclusters by thiol ligands was presented. The photoluminescence (PL) measurements show that the luminescent wave-length of Cu nanoclusters capped by 2-mercapto-5-n-propylpyrimidine (MPP) is gradually blue-shifted from 623 nm to 584 nm, with increasing concentrations of dodecanethiol (C12SH) added into the solution. The added thiol ligands, as suggested by mass spectra, do not change the number of Cu atoms in the clusters, but replace some of the original MPP ligands. X-ray absorption fine structure (XAFS) spectra reveal that with the increment of C12SH ligands, the Cu—Cu bonds disappear, the Cu—S bond length is contracted from the original 0228 nm to 0.224 nm, and the charge transfer from Cu to S is enhanced. Moreover, the etching effect of C12SH ligands leads to the change of atomic configuration of the Cu cores from the tetrahedron-alike structure to the chain-like structure of —S—Cu—S—. As a result, the electronic features of the Cu clusters show a metallic-to-covalent transition, resulting in the blue-shift of the luminescence and optical absorption wavelengths.
Evaluation of pulmonary toxicity of zinc-doped magnetite nanoparticle in mice after intragastric administration
ZHU Shanshan, XU Xiaolong, RONG Rui, LI Bing, WANG Xue
2015, 45(5): 366-372. doi: 10.3969/j.issn.0253-2778.2015.05.004
Zn2+ doped magnetite nanoparticles (ZnaFebO4 NPs) have higher magnetic susceptibility than conventional magnetite nanoparticles (Fe3O4 NPs). Dimercaptosuccinic acid (DMSA)-coated Zn0.4Fe2.6O4 nanoparticles (Zn0.4Fe2.6O4 NPs) were synthesized. The pulmonary toxicity of DMSA-coated Zn0.4Fe2.6O4 NPs in mice was evaluated after oral administration for one month. No abnormal activities among the mice were observed in Zn0.4Fe2.6O4 NPs-treated group during the whole experiment process. The accumulation of Fe in the lungs was observed after oral administration of DMSA-coated Zn0.4Fe2.6O4 NPs in mice. The accumulation of Fe in the lungs resulted in an increase of coefficient of lung, but did not cause obvious pulmonary injury, except for a very slight inflammatory response in the tissue. The results show that low toxic DMSA-coated Zn0.4Fe2.6O4 NPs may be used as drug delivery or imaging contrast agents by oral route.
Comparative study of basin-hopping and the minima-hopping global optimization methods: A case study on Lennard-Jones clusters
YAO Cheng, YAO Yi, HE Shan, ZHAO Jinling
2015, 45(5): 373-378. doi: 10.3969/j.issn.0253-2778.2015.05.005
In order to find a better algorithm for global optimization of Lennard-Jones cluster, two algorithms, basin-hopping and minima-hopping, were used to optimize the structures of 13 particles, 38 particles, and 60 particles Lennard-Jones clusters. Both algorithms find global minima, while the minima-hopping method yields a faster search speed which is at least one order faster than the basin-hopping method.
Numerical simulation of negative streamers at different pressures
LI Zaiguang, ZHU Baoyou, MA Ming
2015, 45(5): 379-387. doi: 10.3969/j.issn.0253-2778.2015.05.006
In order to study the characteristics of negative streamers about lightning initiation at different heights in the thunderclouds, a cylindrically symmetrical two-dimensional model was used to simulate negative streamers between planar parallel plates in nitrogen. In the model, a flux-corrected transport (FCT) technique was used to solve the continuity equations and an adaptive grid refinement strategy was used to increase computing efficiency. The simulation results indicate that, after the initial stage of adjustment the streamers propagate in a steady-state mode, the characteristics of steady-state are decided by background ionization frequency which is determined by pressure and background electric field together. A logarithmic linear relationship can be found between average streamer velocity and the background ionization frequency. Under the same background electric field, the background ionization frequency increases with the decrease in pressure, and streamers develop faster, implying they are more likely to initiate in the region with a relatively lower pressure. At the same pressure, the background ionization frequency increases as the intensity of the background electric field increases and streamers develop faster, and streamers tend to initiate in the region with a stronger background electric field.
Occurrences and bioavailability of cadmium in soils of Guqiao Mine subsidence area, Huainan
CHEN Hui, ZHENG Liugen, CHENG Hua, JIANG Chunlu, CHEN Yongchun
2015, 45(5): 388-396. doi: 10.3969/j.issn.0253-2778.2015.05.007
Cadmium in soils of coal-mining subsidence poses potential ecological risks. DTPA extraction and Tessier sequential extraction methods were used to investigate the speciation and bioavailability of Cd in subsidence soils of Guqiao Coal Mine. The results show that total Cd and availability Cd are highly correlated, and are both enriched in topsoil (0~20 cm). Cadmium in studied soils is 367 times of that in the Huainan background soil, with a high activation rate of 3786%. The proportions of different Cd species in studied soils are: residual fraction (5059%)>exchangeable fraction (2324%)> Fe-Mn oxides bound fraction (1577%)>carbonate bound fraction (618%)>organic bound fraction (422%). Bioavailable (exchangeable) and potentially bioavailable Cd (carbonate bound, Fe-Mn oxide bound, organic bound) account for 2324% and 2617%, respectively, which could be activated under the soil environment of mines. The organic matter, total nitrogen and total phosphor of soil are the main factors controlling Cd species. In addition, the variation of pH values in soil could promote the conversion of Cd in other forms to bioavailable forms.
Effect of non-condensable gas on convective condensation on a short vertical plate
LIU Quan, YANG Jianzhi, GU Hailin, QIAN Wanyi, LIU Minghou
2015, 45(5): 397-403. doi: 10.3969/j.issn.0253-2778.2015.05.008
The effect of mass fraction of non-condensable air, liquid film and velocity of air-vapor mixture on the convective condensation on a short vertical plate was investigated numerically. The volume of fluid (VOF) was applied to model the two-phase flow of liquid film and gases mixture. The species transport between water vapor and air was calculated by the conservation equation for species. A modified phase change model, derived from basic equations related to the kinetic gas theory, was proposed and verified by two different cases. It was found that a small amount of non-condensable gas shows no significant effect on the convective condensation of water vapor. However, the heat transfer coefficient of convective condensation shrinks obviously as air concentration increases. And the heat transfer coefficient is about 8% higher than that of not ignoring liquid film. The heat transfer coefficient of convective condensation improves by increasing inlet velocity of the gas mixture to a lower extent than pure water vapor convection.
High accuracy fluid PVT measurement system based on magnetic suspension densimeter
XU Hang, CAI Xudong, HU Peng, JIN Yi
2015, 45(5): 404-408. doi: 10.3969/j.issn.0253-2778.2015.05.009
A fluid PVT measurement system based on magnetic suspension densimeter was developed. The temperature range is 20315~42315 K with standard uncertainty of 0005 K, and the pressure range is 0~70 MPa with standard uncertainty of 700 Pa. The temperature control system was modified, thus the time reaching equilibrium state was shortened and the temperature stability was improved. The developed PVT system was used to measure the density of high purity nitrogen at 271~345 K, 0~6 MPa, and the average absolute deviation between experimental results and the NIST REFPROP90 data was within 01%, and the density uncertainties due to the uncertainties of fitted virial equation and measured temperature and pressure was analyzed.
Local linearization of finite element method for semi-inverse problem of incompressible flow along S2 stream surface in axial-flow turbomachinery
LV Wenchao
2015, 45(5): 409-415. doi: 10.3969/j.issn.0253-2778.2015.05.010
The application of local linearization of finite element method (FEM) for the semi-inverse problem of incompressible flow along S2 stream surface in axial-flow turbomachinery was discussed. Curved quadrilateral isoparametric elements with eight nodes were used to analyze the flow field for the semi-inverse problem along S2 stream surface in axial-flow turbomachinery through usual variational FEM. Local linearization of FEM was also used to analyze this flow field. The computing result of local linearization of FEM is the same as the usual variational FEM and in good agreement with the experimental result. The computing time of local linearization of FEM is reduced compared with usual FEM, while the required memory of local linearization of FEM increases compared with usual FEM. The computing process shows good convergence properties.
A spatial research on the influencing factors of urbanization in Anhui Province
GOU Xiaoju, XU Rui, FU Yuanguang
2015, 45(5): 416-421. doi: 10.3969/j.issn.0253-2778.2015.05.011
The spatial econometric method was applied to analyze the influencing factors of urbanization based on the panel data of Anhui Province. The spatial lag and error models were constructed in the empirical study to verify the theoretical assumptions. The results show that there exists a strong spatial dependence in urbanization between neighboring cities; the developmental level of secondary and tertiary industries, fixed-asset investment and residents degree of education are the main influencing factors of urbanization; the promoting effect of economic development level on urbanization is not significant; the income gap between urban and rural areas inhibits the development of urbanization. Finally, some suggestions were given on how to promote the urbanization of Anhui Province based on the conclusions.
Empirical research on persistence of Chinas stock market price using ultra-high frequency data
WANG Libin, FANG Zhaoben
2015, 45(5): 422-428. doi: 10.3969/j.issn.0253-2778.2015.05.012
The persistence of extreme stock prices with respect to its volumes of Chinas stock market was investigated through ultra-high frequency data. Studies show that, Chinas stock prices exhibit a weak reversion within a certain range of post volume after extreme prices appear, which is different from the full reversion of the Western stock markets. A new research method and an investment strategy adapting to Chinas stock market were proposed. Empirical research gave the single return and accumulated return of the strategy, as well as the optimal values of parameters and the inter frequency distributions of extreme prices.