Model results for the [Rb/Fe] against [Zr/Fe] for intermediate-mass AGB stars of solar metallicity without the inclusion of a PMZ. The solid part of the lines are equivalent to a TDU efficiency of 0 during the extended evolution. The dashed lines are the result of the synthetic extension when the TDU efficiency is chosen to remain constant. The observed [Rb/Fe] and [Zr/Fe] ranges are indicated by the grey shaded area, note that [Rb/Fe] ranges up to 2.5 ( ± 0.8, see Table 1). (This figure is available in color in the electronic form.)