The structure of the electromagnetic quantum vacuum in a disclinated insulator was considered. It was shown that a non-zero vacuum energy density appeared when the rotational symmetry of a continuous insulating elastic medium was broken by a disclination. An explicit expression was given for this Casimir-energy density in terms of the parameter which described the disclination.

Casimir Effect around Disclinations. F.Moraes: Physics Letters A, 1995, 204[5-6], 399-404