  We investigate nonlinear transport properties of quantum conductors in
response to both electrical and thermal driving forces. Within scattering
approach, we determine the nonequilibrium screening potential of a generic
mesoscopic system and find that its response is dictated by particle and
entropic injectivities which describe the charge and entropy transfer during
transport. We illustrate our model analyzing the voltage and thermal
rectification of a resonant tunneling barrier. Importantly, we discuss
interaction induced contributions to the thermopower in the presence of large
temperature differences.
