Abstract: In an apparatus for culturing cells which comprises a plate-like body with a lattice structure having openings separated from one another by sidewalls and a bottom disposed on one side of the lattice structure and having passages permeable for liquids but not for cells so as to form, with the lattice structure, cavities for receiving cells to be grown therein, the cavities have a clear width of between 50 .mu.m and 1000 .mu.m and the bottom consists of a material to which cells placed into the cavities will not easily attach so that the cells grow from the side walls of the cavities causing them to form a three-dimensional cell structure.

Abstract: In a process for finding the value of parameters which change the resonance frequencies of microstructures wherein the microstructures include at least one membrane mounted at its periphery and wherein at least one resonance frequency of the microstructures is between 100 kHz and 100 MHz, the frequency of the characteristic resonance frequency of the microstructures is detected by exposing the microstructures to ultrasound and measuring the intensity of the ultrasound transmitted through, or reflected from, the microstructure and the value of the parameter is then determined by means of a calibration curve.

Abstract: In a process for treating dissolution residues which are generated in the recovery of fission products, particularly fission molybdenum, wherein nuclear fuel comprising the elements uranium, silicium and aluminum is irradiated and subsequently treated with an alkaline solution from which any dissolution residues are separated, the dissolution residues are dissolved in an additional hydrogen peroxide containing solution to which an acid and iodine or an iodine compound is added whereby a complete dissolution of the residues is achieved.