Surface elemental mass fractions normalized by their initial mass fractions for the nine models with M_ini = 1, 2 and 3 M_⊙, and [Fe/H] = −2, −2.5 and −3. The initial mass is increasing from the top to the bottom panels and the initial metallicity is increasing from the left to the right panels. The patterns correspond to the surface abundances after the indicated pulse number. The bold frames highlights models experiencing a PIE. Unstable isotopes are not beta-decayed and the unstable Z = 43 and Z = 61 elements are not considered since X_ini = 0 for those elements.