Abstract: A pressure control system for a bioreactor of the type having a gas space and a cell culture space therein is supplied with a gas such as oxygen separately from the supply of liquid nutrient media. The pressures in the gas space and the pressure in the cell culture space are controlled so that a higher pressure is maintained in the cell culture space than in the gas space to prevent displacement of the liquid nutrient media.

Abstract: An electrodynamic transducer (10) is disclosed for non-destructive material testing comprising at least one internal pole shoe (16) of an electromagnet with core (12) and magnetic winding (14). The end section (18) of the internal pole shoe (16) is arranged eccentrically in relation to the center axis (29) of the core (12) and is designed to rotate with the core (12) about the center axis (29) thereof.

Abstract: An electro-dynamic transducer head (107) coming into contact with a workpiece (14) comprises a protective cap (28, 38), which is at least partially surrounded by a sliding protection element (22). The sliding protective element has a basic member (24) with sections (26), which are introduced into recesses (28) by deposit welding.

Abstract: An electrodynamic transducer head for the non-destructive ultrasonic testing of workpieces (12) comprises an electromagnet having a magnet yoke with an external pole shoe and an internal pole shoe (10, 14) surrounded by the external pole shoe. Exciting and receiving coils (16, 18) are arranged on these pole shoes. To enable the internal pole shoe (10, 14) to be placed directly on the workpiece (12) moving relative thereto without danger, these pole shoes are provided with a protective cap (20) surrounded by a protective ring (22), the end face of the protective ring (22) turned towards the workpiece (12) projecting beyond that of the protective cap.

Abstract: An electrodynamic instrument transformer head (10) for the non-destructive testing of materials by means of ultrasonics has a pole shoe (20) provided with exciting and receiving coils (14, 16), said pole shoe comprising a slotted end section (24) to prevent a formation of eddy currents. The end section (24) thereby is continuing into a basic body (22) preferably being made of a different material.