A clamping device for grasping and suspending a workpiece is disclosed. Described are the particular microbiocides used and the substantial advantages of using such materials, in some cases as concentrated solutions and in other cases as dilute solutions. The shade element is suspended from the first winding roller and the second winding roller in such a manner that one of the screen sections is extended into or retracted from a target area as the first winding roller and the second winding roller are rotated by the actuator. The control circuit might also take other remedial steps prior to initiating the alarm.