  We review a simple technique for evaluating the vacuum energy stemming from
non-trivial boundary conditions and review results for the Casimir energy of a
massive fermionic field confined in a d+1-dimensional slab-bag and the effect
of a uniform magnetic field on the vacuum energy of confined massive bosonic
and fermionic fields. New results concerning the Casimir energy and the
evaluation of the rate of creation of quanta in kappa-deformed theories are
presented.
