  It is shown that the quark mass density-dependent model can not be used to
explain the process of the quark deconfinement phase transition because the
quark confinement is permanent in this model. A quark mass density- and
temperature-dependent model in which the quark confinement is impermanent has
been suggested. We argue that the vacuum energy density B is a function of
temperature. The dynamical and thermodynamical properties of bulk strange quark
matter for quark mass density- and temperature-dependent model are discussed.
