The cover picture illustrates how the optical properties of InP/ZnSe/ZnS quantum dots (QDs) can be modulated by controlling thickness ZnSe intermediate shells. circles in top left, center, and bottom right represent QDs with thick, middle, thin shells, respectively. Upon excitation blue light, they emit different colors intensities depending on number photons entering exiting QDs. A model QD is...

Two types of models for the formation of semi-periodic concentric multiple shells (M-shells) around asymptotic giant branch (AGB) stars and in planetary nebulae are compared against observations. Models that attribute the M-shells to processes in an extended wind acceleration zone around AGB stars result in an optically thick acceleration zone, which reduces the acceleration efficiency in outer...