Section 83B. County commissioners in carrying out their responsibilities as trustees of county institutions under section eighty-two shall raise and expend such sums of money for acquiring land and constructing and equipping buildings including out-patient and diagnostic facilities and for the alteration and enlargement of existing buildings, for care, maintenance, and repair of all facilities, and for all other purposes as authorized by the general court, except for such temporary financing as provided in section eighty-five A. They may borrow, on the credit of the county, when so authorized by the general court, the said sums, and issue notes of the county therefor, with such interest as may be fixed under section thirty-nine of chapter thirty-five, payable semi-annually, or without interest, in which case they may sell such notes at such discount as they deem proper. The notes shall be signed by the county treasurer and countersigned by the county commissioners. The county may sell the said securities, at public or private sale, on terms and conditions deemed proper, but the proceeds shall be used only for the purposes for which such securities are issued. Said notes may be renewed from time to time without specific authorization from the general court until all the cities and towns liable have paid to the county treasurer the amounts assessed against them. Any amount of interest paid or due on said notes and renewals thereof may be similarly borrowed. All reimbursement from cities and towns on such assessments shall be applied to the payment of temporary debt incurred under this section. Such assessments shall be made against the cities and towns in the county in accordance with their valuation used in assessing county taxes and shall be paid in such manner and such installments as the commissioner shall by special order direct. If any city or town shall neglect or refuse to pay its proportion as required by said order, the county commissioners shall, after notice to the city or town and unless sufficient cause is shown to the contrary, issue a warrant against it for the sum which it was ordered to pay, with interest, and the costs of the notice and warrant; and the same shall be collected and paid into the county treasury, to be applied in payment of the expenses aforesaid.