[en] Structure of nanoparticle aggregates plays an important role in microwave extinction capacity. The diffusion-limited aggregation model (DLA) for fractal growth is utilized to explore the possible structures of nanoparticle aggregates by computer simulation. Based on the discrete dipole approximation (DDA) method, the microwave extinction performance by different nano-carborundum aggregates is numerically analyzed. The effects of the particle quantity, original diameter, fractal structure, as well as orientation on microwave extinction are investigated, and also the extinction characteristics of aggregates are compared with the spherical nanoparticle in the same volume. Numerical results give out that proper aggregation of nanoparticle is beneficial to microwave extinction capacity, and the microwave extinction cross section by aggregated granules is better than that of the spherical solid one in the same volume. (paper)

[en] In tin dioxide nanostructures, oxygen vacancies (OVs) play an important role in their optical properties and thus regulation of both OV concentration and type via external strain is crucial to exploration of more applications. First-principle calculations of SnO_2 (110) surface disclose that asymmetric deformations induced by external strain not only lead to its intrinsic surface elastic changes, but also result in different OV formation energy. In the absence of external strain, the energetically favorable oxygen vacancies(EFOV) appear in the bridging site of second layer. When -3.5% external strain is applied along y direction, the EFOV moves into plane site. This can be ascribed that the compressed deformation gives rise to redistribution of electronic wave function near OVs, therefore, formation of newly bond structures. Our results suggest that different type OVs in SnO_2 surface can be controlled by strain engineering.

[en] An effective Gross-Pitaevskii equation, which describes the dynamics of quasi-one-dimensional Bose-Einstein condensates in specific potential traps, is considered, and new families of exact solutions are reported, which include periodic and solitary waves. The solutions are applied to the description of BEC patterns trapped in optical-lattice potentials

[en] Regulation of magnetism and half-metallicity has attracted much attention because of its potential in spintronics. The magnetic properties and electronic structure of graphitic carbon nitride (g-C₄N₃) with external strain are determined theoretically based on the density function theory and many-body perturbation theory (G₀W₀). Asymmetric deformation induced by uniaxial strain not only regulates the magnetic characteristics but also leads to a transformation from half-metallicity to metallicity. However, this transition cannot occur in the structure with symmetric deformation induced by biaxial strain. Our results suggest the use of strain engineering in metal-free spintronics applications