  We consider the interaction between a ZnO nanorod and a SiO2 nanorod in
bromobenzene. Using optical data for the interacting objects and ambient we
calculate the force - from short-range attractive van der Waals force to
intermediate range repulsive Casimir-Lifshitz force to long range entropically
driven attraction. The nonretarded van der Waals interaction is attractive at
all separations. We demonstrate a retardation driven repulsion at intermediate
separations. At short separations (in the nonretarded limit) and at large
separations (in the classical limit) the interaction is attractive. These
effects can be understood from an analysis of multiple crossings of the
dielectric functions of the three media as functions of imaginary frequencies.
