Abstract: The subject of the present invention is a lipidoid of general formula (I), wherein X, Y, Z and R are as defined in the claims. This lipidoid is useful as a transfection agent. The invention further describes transfection agents, transfection particles containing this lipidoid, and their use.

Abstract: A positioning mechanism for a magnetic fixed (or hard) disk storage unit incorporates a bearing block forming part of the magnet system for the rotational positioner, and carrying a positioning shaft. A pivot member rotationally seated on the shaft has pivot arms carrying magnetic heads and brackets for carrying the magnetic coil for positioning the heads. A pulse operated detent magnet is provided and incorporates a stop armature. The armature is biased into detent retaining position, but is restrained by retaining spring in mechanically self-holding condition. It is automatically released when the pivot member swings into the detent position, corresponding to the landing zone for the magnetic heads.

Abstract: A rotational positioner for a magnetic disk memory comprises a pedestal constituting a portion of the positioning magnet system and a positioner shaft. In a one-piece pivot member, pivot arms and bracket arms are integrated and disposed in common on a hub. Each pivot arm comprises a device at its free end for releasably receiving a head base plate which carries a pair of magnetic heads by way of a magnetic head mount.