Abstract: A safety apparatus for use in administering radioactive serums by a syringe, without endangering the health and safety of the medical operators, consists of a sheath and a shield which can be retracted into the sheath to assay the radioactive serum in an assay well. The shield can be moved from the retracted position into an extended position when the serum is to be injected into the patient. To protect the operator, the shield can be constructed of tantalum or any like high density substance to attenuate the radiation, emanating from the radioactive serums contained in the syringe, from passing to the atmosphere. A lead glass window is provided so that the operator can determine the exact quantity of the radioactive serum which is contained in the syringe.

Abstract: A method and apparatus for cutting cylinders of gelatinous material such as polyacrylamide gels into discs of precise thickness comprises a cutting surface which is placed in contact with the entire circumference of the cylinder. Cutting force is then applied from all points on the circumference at once, resulting in cutting the gel cylinder towards the center from all points on the circumference. This is accomplished by the use of a multi-bladed diaphragm similar to an iris diaphragm used for camera aperture control. The edges of the blades of the diaphragm form a variable dimension cutting surface.