Is it permissible to shake the hand of one's maternal aunt's husband? And is it permissible to uncover one's head in front of him?

It is not permissible to shake hands with the maternal aunt's husband or to remove the head covering in front of him, because the prohibition between them is temporary, ceasing with the removal of its cause, which is the aunt being in his wedlock. Thus, it is permissible for him to marry her [the niece] immediately after her [the aunt's] death or divorce. A temporary prohibition does not permit seclusion, shaking hands, or removing the head covering.