Abstract: A method for measuring the efficacy of a dental care product with respect to plaque removal on the teeth of a volunteer, comprising the steps: a) requesting selection of a plaque index system on a display device; b) requesting selection of a model tooth to be examined and display of the selected model tooth on the display device; c) requesting input of the plaque data on the model tooth displayed on the display device according to the selected plaque index. d) repeating steps b) and c) for a predetermined number of teeth; and e) determining the percentage amount of plaque for each tooth by calculating the ratio of the area covered with plaque to the tooth surface, wherein the area covered with plaque is calculated according to the selected plaque index.

Abstract: An apparatus for desalination and purification of water by reverse osmosis and ultrafiltration. Such apparatus require seals at the individual modular elements between the untreated water passages and the permeate-withdrawal passages. These seals comprise two sealing rings which are essentially U-shaped, are of similar but inverted shape, and are made of synthetic material having a limited flexibility. Pairs of the sealing rings sealingly abut one another in the central plane of the modular guide plate via respective ones of their arms which extend essentially radially. The second, outward disposed arms sealingly contact an adjacent diaphragm. Disposed on the outer surface of the portion which connects the arms are channels for the withdrawal of the permeate.

Abstract: For filtering and separating liquid and gaseous media, particularly for water desalinization by reverse osmosis, modules filled with membrane cushions are employed that are open at two opposite sides and are inundated within an outer housing by an entering medium. The medium which enters into the interior of the membrane cushion is led away by means of aligned cushion holes and a conduit located in these holes. According to the invention, it is proposed that where there is a tandem series of several membrane cushion modules in a common housing, the stacked modules not be connected securely to one another and that a turbulence producing gap between them be permitted so that undesirable operational behavior does not occur in the form of pressure waves, pressure surges and blockage action with changes in the rate of flow and particularly upon starting the system for the first time.

Abstract: An apparatus for the desalination and purification of water by reverse osis and ultrafiltration. The apparatus includes dish-like carrier plates and water guide plates held between two end plates and alternately stacked one above the other. The apparatus also includes annular diaphragms which lie between respective carrier plates and guide plates and are each backed by a filter layer, so that in use untreated water flows over the diaphragms in the radial direction on the side opposite the filter layer, and permeate or water suitable for industrial use is drawn off at the side backed by the filter layer. The stack of end plates, carrier plates, and guide plates is clamped or held together at the periphery and has a continuous central aperture for the introduction of the untreated water. The carrier plates sealingly engage one another by means of thickened marginal portions lying radially beyond the edges of the guide plates.