This invention is to provide a hydrodynamic bearing assembly, which realizes the high rotation rate in a stable manner and the robust rigidity. When used as an electronic device material, and particularly as a hole transport andor hole injection material, the aromatic compound can achieve a higher current density at a given voltage. An assembly is also disclosed, which includes a fan heater as aforesaid, wherein at least two adapter plates, each exhibiting at least one fastening element for fixing the fan heater to a location intended for it and devices for fixing optionally one of the adapter plates to a housing in the fan heater, are provided.