Section 25. The secretary, administrators, and directors of the department shall be sworn to the faithful performance of their official duties. The secretary and each administrator, and director shall: conduct themselves in a manner so as to render decisions that are fair and impartial and in the public interest; avoid impropriety and the appearance of impropriety in all matters under their jurisdiction; avoid all prohibited communications; require staff and personnel subject to their direction and control to observe the same standards of fidelity and diligence; disqualify themselves from proceedings in which their impartiality might reasonably be questioned; refrain from financial or business dealings which would tend to reflect adversely on impartiality, although the secretary, administrators, and directors may hold and manage investments which are not incompatible with the duties of their office or of this section; and conform to such additional rules as may be prescribed by the secretary from time to time.