Effects of High Pressure on BC3

High-pressure phases of BC3 are studied within the local density approximation under the density functional theory framework. When the pressure reaches 20 GPa, the layered BC3 that is a semiconductor at ambient pressure, becomes metallic. As the pressure increases, the material changes into a network structure at about 35 GPa. To understand the mechanism of phase transitions, band structure and density of states are discussed. With the increase of pressure, the width of bands broadens and the dispersion of bands enlarges. Additionally, the density of states of the network bears great resemblance to that of diamond. Formation of the sp3 bonding in the network is the main reason for the structural transformation at 35 GPa.     

一类具有空间异质和扩散的SVIR模型的全局稳定性

考虑了一类具有空间异质和反应扩散的SVIR传染病模型.当基本再生数等于1时,假定扩散系数为常数,证明了系统的无病平衡态是全局渐近稳定的.     

一类具有扩散和Beddington-DeAngelis反应函数的病毒模型的全局稳定性

研究了一类具有扩散和Beddington-DeAngelis反应函数的病毒模型.通过构造Lyapunov函数,证明了模型的感染平衡点是全局渐近稳定的.