A card reader includes a card locking mechanism locking a card medium in an immovable holding position when the card medium inserted from a card insertion port provided in a front section of a card reader body stops because of abnormal stopping, thus preventing wrongful removal of the card medium by withdrawal. In a print on a second surface of the sheet, the recorded reference mark is read, and a print position of the image on a second surface of the sheet is set. This is achieved in embodiments of the invention using an optimized single-branch fully differential structure which operates as a \u201ccomposite\u201d source-follower with an ideal unitary dc gain. Monitoring and maintenance of optimum stoichiometry in such a reaction is critical to ensuring desired polycarbonate product quality. The mesoporous materials have pore diameters of from about 20 to about 100 and may be used with a biologically active agent immobilized within the pores of the mesoporous material and introduced into a biological system.