  The effects of plasma elemental composition and ionization state on the
effective decay rate of 44Ti are investigated. We essentially follow the
methods of the first authors to treat this topic, Mochizuki et al., but use
more realistic plasma models, including radiative cooling, to compute the
evolution of the charge state distribution behind the reverse shock. For
uniform density ejecta (i.e. no clumps or bubbles) we find a negligible change
to the decay rate of 44Ti. We discuss the effects of non-uniform ejecta. We
also briefly consider the effects on these calculations of collisionless
electron heating associated with weak secondary shocks propagating throughout
the Cas A shell as a result of foward or reverse shock encounters with density
inhomogeneities, recently suggested as an explanation for the hard X-ray tail
seen in BeppoSAX and RXTE/OSSE spectra.
