Abstract: A pyrazolidine derivative or a salt thereof in accordance with the present invention is expressed by the following formula 1: ##STR1## wherein A represents a group expressed by --CH.sub.2 --, --CO--, --CS--, --CH.sub.2 CO--, or --CH.dbd.CH--CO--; B represents a group expressed by --O-- or --NH--; n is an integer of 1 or 2; R represents an alkenyl group; and R.sub.1 and R.sub.2 represent a lower alkyl or benzyl group.The pyrazolidine derivative above mentioned, as a radical scavenger, has antioxidant effect and lipid peroxidation inhibitory activity so as to be available for inhibiting brain infarction or brain edema.

Abstract: In a safety-deposit box system including a safety-deposit box, a system controller, and a safety-deposit box controller, a multi-function key is used. The safety-deposit box has a lock and the multi-function key has a metal portion and an electronic memory. Information electronically stored on the electronic memory is read by a reception device and sent to a determination device in the system controller. The determination device compares the sent information with information prerecorded in an electronic memory in the system controller. When the two sets of information agree, the system controller outputs a signal to the safety-deposit box controller. After receiving the signal, the safety-deposit box controller checks mechanical appropriateness of the metal key portion and, if mechanically appropriate, unlocks the lock.