A device for positioning sheets in a station of a sheet-processing machine comprising a movable bearing surface for holding at least one edge zone of a sheet, actuators driving the bearing surface in the plane thereof, gripping means accompanying the motion of the bearing surface and adapted to grip or release the edge zone of the sheet between a sheet-gripping means and the bearing surface. In one embodiment, a reactor for depositing material onto a micro-device workpiece includes a reaction chamber, a lid attachable to the reaction chamber, and a connector. A central beam assembly stands upwardly of the center sill. In an embodiment, the client control system may include dual primary client controllers that continually request information from the server IEDs using multiple of the communication paths. A single-compartment system can be used, which includes a spray chamber including a circulatory spray-cycle system; a support for holding the work piece; and a media container connected to the spray chamber via a media circulation system. Accordingly, the video display apparatus switches the video format of the screen.