Stable suspension and dispersion-induced transitions from repulsive   Casimir forces between fluid-separated eccentric cylinders
  Using an exact numerical method for finite nonplanar objects, we demonstrate a stable mechanical suspension of a silica cylinder within a metallic cylinder separated by ethanol, via a repulsive Casimir force between the silica and the metal. We investigate cylinders with both circular and square cross sections, and show that the latter exhibit a stable orientation as well as a stable position, via a method to compute Casimir torques for finite objects. Furthermore, the stable orientation of the square cylinder is shown to undergo an unusual 45 degrees transition as a function of the separation lengthscale, which is explained as a consequence of material dispersion. 
Alejandro W. Rodriguez, J. N. Munday, J. D. Joannopoulos, Federico   Capasso, Diego A. R. Dalvit, and Steven G. Johnson