The present invention relates to a lid for closing a centrifuge rotor, characterized by a form-fitting, rotation-actuated closure mechanism which, pre-positioned on the centrifuge rotor, moves automatically into a closed position by virtue of the intrinsic weight of the lid. The clay plaster is a mixture of various clays, and aggregate. The DC path includes an inductor or an LC parallel resonator. A first end of the conductive thermal channel is coupled to a first semiconductor material and a second end of the conductive thermal channel is coupled to a second semiconductor material, the first semiconductor material being coupled to the hot region and isolated from the cold region and the second semiconductor material being coupled to the cold region and isolated from the hot region.