  We propose a simple idea to construct 1D integrable models with impurities.
We illustrate the strategy for a supersymmetric $t-J$ Hamiltonian in
considerable detail. The impurity comprises the local deformation of the
hopping and exchange integrals as well as a three-body charge-current
interactions on neighboring sites. We explore the thermodynamic properties of
the system at low and high temperatures, and obtain results that are beyond
boundary conformal-field theory.
