Abstract: Polymerizable oligo- and/or polyalkenoic acids are disclosed which are block polymers of different polyalkenoic acids or their derivatives and/or conjugated dienes. These oligo-/polyalkenoic acids are characterized in that they have at least one sequence with acid functions or protected acid functions in the side group and at least one sequence with olefinic double bonds in the side group of the alcohol component of the esters or the amine component of the amides. The use of said polymerizable oligo- and/or polyalkenoic acids for dental/medical purposes is also described.

Abstract: A method and an apparatus for measuring the flow velocity of a flow, stream or jet of molten radiation emitting material, in particular a freely falling jet of molten glass. The intensity of the radiation emitted from a limited section of the material flow is detected by means of two radiation detectors at two separate locations mutually spaced apart by a predetermined distance along the flow path of the material flow. From the output signals of the two radiation detectors all pulse-like amplitude variations having an amplitude exceeding a predetermined magnitude are discriminated. These pulse-like amplitude variations originate from randomly occurring, local, descrete, short variations in the intensity of the radiation emitted by the material flow caused by randomly occurring inhomogeneities in the material, for instance in the form of air bubbles in a jet of molten glass.