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Ti2AlC/TiAl composites with different volume fractions were prepared by hot pressing technology, and their reinforced structural characteristics and mechanical properties were evaluated. The results showed that when the reinforced phase volume fraction of Ti2AlC was 20%, three-dimensional interpenetrating network structures were formed in the composites. Above 20%, Ti2AlC phase in the composites accumulated and grew to form thick skeletal networks. The microplastic deformation behavior of Ti2AlC phase, such as kink band and delamination, improved the fracture toughness of the composites. Comparative analysis indicated that the uniform and small interconnecting network structures could further reinforce the composites. The bending strengths of composites prepared with 20 vol.% Ti2AlC reached (900.9±45.0) MPa, which was 25.5% higher than that of TiAl matrix. In general, the co-continuous Ti2AlC/TiAl composite with excellent mechanical properties can be prepared by powder metallurgy method.

On the basis of the Landauer-Buttiker scattering formalism and transfer matrix method, we investigated the spin-dependent shot noise in parabolic-well with two ferromagnetic contacts (F/PW/F). The quantum size and Rashba spin-orbit interaction are discussed simultaneously. The results indicate that the shot noise is periodic function of the parabolic-well width. The oscillation frequencies of the shot noise decrease with the increasing of the parabolic-well depth, and increase with the increasing of the Rashba spin-orbit coupling strength. The amplitude and peak to valley ratio of the shot noise are strongly dependent on the magnetization configuration of the junction.

We have investigated theoretically the gas phase reactions of dimethyl sulfoxide (DMSO) with atom Cl in the absence and presence of a single water molecule. The calculations of the potential energy surfaces in the water-free and water-assisted along the different channels are performed at the CCSD(T)/6-311++G(2df,2p)//MP2/6-31G(d) level. The calculated results show that energy barriers of the Hc-abstraction reaction are reduced due to one water molecule added. The computed rate constants of Hc-abstraction reaction indicate that the reaction with water is faster than the value of the naked reaction. However, Ha-abstraction reaction, path2, path3, and path4 are slower without water than hydrous channels.

The initial reactions of HO2 with oxalyl dichloride, oxalyl dibromide, acetyl chloride, and acetyl bromide are studied for the first time using the density functional theory with CAM-B3LYP and wB97XD, CBS-QB3, and G3 theoretical methods and the transition state theory. The reactions occur via the similar mechanism that the prereactive complex is formed before the transition state and product. The calculated results demonstrate that the HO2 radical with ClC(O)C(O)Cl and BrC(O)C(O)Br reactions is feasible and could play a significant role in the atmosphere because the barriers are 0.13 kcal/mol, −0.05 kcal/mol with respect to the free reactants, respectively at the CBS-QB3 level of theory. In addition, the rate constants of the HO2 + ClC(O)C(O)Cl and HO2 + BrC(O)C(O)Br reactions are computed to be 1.37 × 10−15 cm3 mol−1 s−1, 1.70 × 10−15 cm3 mol−1 s−1 at 298 K. However, the HO2 reactions with acetyl chloride and acetyl bromide are of no importance because of higher activated barrier and slower rate constant. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Stimulated emission has been observed from oxide structure of silicon when optically excited by 514 nm laser. The twin peaks in the region from 690 nm to 700 nm are dominated by stimulated emission which can be demonstrated by its threshold behavior and transition in linear evolution. The oxide structure was fabricated by laser irradiation and annealing treatment on silicon. A model for explaining the stimulated emission has been proposed in which the trap states of the interface between oxide of silicon and porous nanocrystal play an important role.

It is shown that the Dirac equation for a new equal scalar and vector anharmonic oscillator potentials could be separated into a solvable angular equation and a radial equation. Corresponding exact solutions of bound states for the Dirac equation have been obtained. The angular solutions are the associated-Legendre polynomial and the radial solutions are expressed in terms of the confluent hypergeometric functions. Finally, the energy equation is found from the boundary condition satisfied by the radial wavefunction.