Speciation of aluminium fluoride complexes and Al in soils from the vicinity of an aluminium smelter plant by hyphenated High Performance Ion Chromatography Flame Atomic Absorption Spectrometry technique

The paper presents a new tool for the determination of inorganic speciation forms of aluminium: AlF_n^{(3 − n)+}, and Al³⁺ by means of the HPIC-FAAS. The proposed method has been successfully used for speciation analysis (qualitative and quantitative) of inorganic aluminium forms AlF_n^{(3 − n)+} in soil samples. In order to isolate the most environmentally available fraction, 5 g of the sample was collected and extracted in deionised water (water soluble fraction) for 1 h using a magnetic stirrer. The determinations in a hyphenated technique system were performed for a number of prepared water extracts. Concentration determinations of particular aluminium forms were performed based on model studies and real samples. The separation of Al species with nominal charge of + 1, + 2, and + 3 required a run time of less than 4 min during a single analysis. Based on the analysis of water extracts of soil, it was obtained that aluminium forms elute in the following order: 1PA (first signal) — AlF₂⁺ and/or AlF₄⁻; 2PA (second signal) — AlF²⁺ and/or AlF₃⁰; 3PA (third signal) — Al³⁺. In order to confirm the occurrence of these forms a simulation using the Mineql program was conducted. The details of speciation analysis of aluminium fluoride forms by means of an HPIC-FAAS instrument equipped are presented. Interpretation of the speciation analysis of the water soluble fraction of soil samples is proposed, based on the separation during chromatographic run and calculated data by Mineql.     

第一原理分子动力学研究类金刚石薄膜的结合强度与摩擦性能

金刚石(110)表面具有不同方向上抛光速率的强烈不对称的特征,用第一性原理全能量平面波赝势方法模拟研究了类金刚石薄膜表面的结合强度与摩擦性能,确定了相互作用模型以及排斥力作用范围,研究了范德华排斥力在摩擦表面上的分布,研究结果表明,摩擦表层感受到的力在〈001〉和〈110〉2个方向上表现明显不同,而且〈110〉方向上摩擦力一直高于〈001〉方向上的摩擦力.     

Traveling wave solutions for two nonlinear evolution equations with nonlinear terms of any order

In this paper, based on the known first integral method and the Riccati sub-ordinary differential equation (ODE) method, we try to seek the exact solutions of the general Gardner equation and the general Benjamin-Bona-Mahoney equation. As a result, some traveling wave solutions for the two nonlinear equations are established successfully. Also we make a comparison between the two methods. It turns out that the Riccati sub-ODE method is more effective than the first integral method in handling the proposed problems, and more general solutions are constructed by the Riccati sub-ODE method.     

MgO-decorated carbon nanotubes for CO2 adsorption: first principles calculations

The global greenhouse effect makes it urgent to deal with the increasing greenhouse gases.In this paper the performance of MgO-decorated carbon nanotubes for CO 2 adsorption is investigated through first principles calculations.The results show that the MgO-decorated carbon nanotubes can adsorb CO 2 well and are relatively insensitive to O 2 and N 2 at the same time.The binding energy arrives at 1.18 eV for the single-MgO-decorated carbon nanotube adsorbing one CO 2 molecule,while the corresponding values for O 2 and N 2 are 0.55 eV and 0.06 eV,respectively.In addition,multi-molecule adsorption is also proved to be very satisfactory.These results indicate that MgO-decorated carbon nanotubes have great potential applications in industrial and environmental processes.     

A CASTEP study on magnetic properties of C-doped ZnO crystal

The CASTEP calculations based on the density function theory (DFT) have been carried out in studying magnetic properties of C-doped ZnO crystal. The long-range ferromagnetism (FM) can be attributed to coupling between C energy levels. We also investigate effects of oxygen vacancies and nitrogen impurities on FM properties. It is obvious that oxygen vacancies are unfavorable to stabilize the FM. However, nitrogen impurities can enhance FM coupling, which indicates that hole-carriers play a crucial role in the observed FM behavior. In addition, we also analyze strain effect on FM of C-doped ZnO.     

O2在Mo(001)表面吸附的第一原理研究

采用第一原理方法计算了O2分子在 Mo(001) 表面的吸附,得到了吸附构型的各种参数,并且计算了O2分子在 Mo(001) 表面4个位置（顶位,桥位,穴位垂直,穴位平行）吸附后的能量,结果表明在顶位吸附能最高。通过对O2分子在 Mo(001) 表面吸附的原子轨道电荷分布与态密度图的分析可以看出在吸附过程中主要是O原子的2p轨道电子与钼的4s和4d轨道电子的相互作用。     

Traveling wave solutions for two nonlinear evolution equations with nonlinear terms of any order

In this paper, based on the known first integral method and the Riccati sub-ordinary differential equation (ODE) method, we try to seek the exact solutions of the general Gardner equation and the general Benjamin-Bona-Mahoney equation. As a result, some traveling wave solutions for the two nonlinear equations are established successfully. Also we make a comparison between the two methods. It turns out that the Riccati sub-ODE method is more effective than the first integral method in handling the proposed problems, and more general solutions are constructed by the Riccati sub-ODE method.     

Escape process and stochastic resonance under noise intensity fluctuation

We study the effects of noise intensity fluctuations on the stationary and dynamical properties of an overdamped Langevin model with a bistable potential and external periodical driving force. We calculated the stationary distributions, mean-first passage time (MFPT) and the spectral amplification factor using a complete set expansion (CSE) technique. We found resonant activation (RA) and stochastic resonance (SR) phenomena in the system under investigation. Moreover, the strength of RA and SR phenomena exhibit non-monotonic behavior and their trade-off relation as a function of the squared variation coefficient of the noise intensity process. The reliability of CSE is verified with Monte Carlo simulations.     

静态球对称黑洞热力学与爱因斯坦场方程

建立在广义相对论基础上的黑洞理论与热力学定律之间有着深刻的内在联系.具体考虑球对称黑洞,研究表明通过史瓦西黑洞和Reissner-Nordstrom黑洞在其视界附近的爱因斯坦场方程可以直接得到对应的黑洞热力学第一定律.这揭示了爱因斯坦引力场方程与黑洞热力学的关系,表明了在广义相对论理论框架下黑洞热力学规律的必然性.     

Cohomology of the Schrdinger Algebra S(1)

We explicitly compute the first and second cohomology groups of the Schrdinger algebra S(1) with coefficients in the trivial module and the finite-dimensional irreducible modules.We also show that the first and second cohomology groups of S(1) with coefficients in the universal enveloping algebras U(S(1))(under the adjoint action) are infinite dimensional.