Reinfection in patients with COVID-19: a systematic review.

Background: With the continuation of the COVID-19 pandemic, some COVID-19 patients have become reinfected with the virus. Viral gene sequencing has found that some of these patients were reinfected by the different and others by same strains. This has raised concerns about the effectiveness of immunity after infection and the reliability of vaccines.

Pressure-Induced Structural Phase Transition and Superconductivity in NaSn.

The structural and electronic properties of the tin-rich compound NaSn were investigated under pressures of up to 10 GPa on the basis of the evolutionary algorithm (EA) technique coupled with first-principles total energy calculations. Upon compression, the known metallic tetragonal 4̅2 phase transforms into a metallic hexagonal 6/ phase at 1.85 GPa accompanied by an unusual change in the existing form of Sn atoms.

Structural diversity and electronic properties in potassium silicides.

Stable potassium silicides in the complete compositional landscape were systematically explored up to 30 GPa using the variable-composition evolutionary structure prediction method. The results show that KSi, KSi, KSi, KSi, KSi, KSi, KSi, KSi, and KSi have their stability fields in the phase diagram. The spatial dimensional diversity of polymerized silicon atoms (0D "isolated" anion, dimer, Si group, 1D zigzag chain, 2D layer, and 3D network) under the potassium sublattice was uncovered as silicon content increases.