Abstract: Disclosed are spherical particles of a polyorganosilsesquioxane resin have a unique optical properties when each particle has a core-cladding composite structure consisting of a core portion of, for example, a polymethylsilsesquioxane resin and a cladding layer of, for example, a polyphenylsilsesquioxane resin having refractive indices differing by at least 0.02, the diameter of the core portion being in a specified range relative to the diameter of the whole particle. Such particles of a core-cladding structure can be prepared by conducting the hydrolysis-condensation reaction of organotrialkoxysilanes, e.g., methyl trimethoxysilane and phenyl trimethoxysilane, in two successive steps by using different silane compounds or by using silane mixtures of different mixing proportion in the first and second step reactions.

Abstract: A medical apparatus for the extracorporeal treatment of blood or plasma comprises a semi-permeable membrane consisting of at least one electronegative polymer, such that the surface of the semi-permeable membrane has negative electric charges. Before the sterilization of the apparatus, and before or after the formation of the membrane, at least one cationic and anti-protease agent is incorporated in at least one part of the membrane, this agent undergoing bulk adsorption or semi-bulk adsorption in the membrane and/or being bound by an ionic interaction with the electronegative sites of the membrane.