Abstract: A serum separating sealant having a specific gravity at 20.degree. C. of 1.035 to 1.065, a viscosity of 100 to 400 Pa.S and a yield stress of 100 to 400 dyne/cm.sup.2 and comprising:(A) 100 parts by weight of a polymer having specific gravity at 20.degree. C. of 0.94 to 1.06 and a viscosity of 10 to 140 Pa.S, derived from an alkyl acrylate or alkyl methacrylate monomer having the formula (I): ##STR1## wherein R.sup.1 denotes H or CH.sub.3, R.sup.2 denotes an alkyl group having 1 to 18 carbon atoms;(B) 0.5 to 10 parts by weight of at least one component selected from silica and bentonite; and(C) 0.01 to 2 parts by weight of at least one surfactant selected from the group consisting of:(C-1) fluorocarbon-based surfactants;(C-2) polyester modified alkylpolysiloxane based surfactants.

Abstract: Disclosed is a contrast medium for ultrasonic diagnosis, which comprises an aqueous medium and gas-encapsulated particles each having a ferrite magnetic layer on the surface thereof contained in the aqueous medium.

Abstract: An immunoassay method using magnetic particles comprising a core and a coating layer on the surface thereof, The core comprises an organic polymer and the coating layer comprises an iron oxide type ferrite coating layer. An antigen or an antibody is bound onto the surface of the coating layer and the particle has a particle size of 0.2 to 3 .mu.m.

Abstract: Cellulose derivatives such as cellulose nitrate, cellulose acetate, cellulose acetate butyrate or ethyl cellulose may be cross-linked with a synthetic film-forming resin such as acrylic resin, alkyd resin, epoxy resin, aminoplast resin or mixtures of these resins by first reacting said cellulose derivative with a polyisocyanate compound to give an addition-reaction product containing free isocyanate groups, then reacting the resulting product with said film-forming resin. The resulting cross-linked hybrid polymers exhibit remarkably advantageous properties as a film-forming component for use in lacquer type coating compositions.