Provided are methods of modulating the persistence of the expression in a cell of a transgene, such as a transgene in a non-Herpes vector or in at least E4 adenoviral vector, and related systems. The novel projectile includes a body, a first mechanism for spin stabilizing the body during a first mode, and a second mechanism for fin stabilizing the body during a second mode. The graphene cathode field emission X-ray tube also has the characteristics of good stability and long service life. The top end cover is disposed on the top of the housing.