Section 13
SEC. 13. After due hearing, the board may, at its discretion, either suspend temporarily or revoke the validity of any certificate issued under this Act for unprofessional conduct of the holder or other sufficient cause: Provided, That written notice shall have been mailed to the holder of such certificate at least twenty days before the hearing thereon, stating the cause of such contemplated action, and appointing a day for such hearing; and the defendant shall be given full opportunity to defend himself personally or by counsel from the charge.