Rotary pumps; rotary mechanical fluid mixing machines; magnetic bearings as machine parts; rotary machines, namely mechanical mixing machines having rotating parts supported by magnetic levitation bearings, and mechanical mixing machines having rotating parts supported by non-rotating bearings not in contact with the rotating parts; electric pump housed by magnetic force; seal piston rings for pump heads; impellers for pumps; electric pumps for pumping blood; electric pumps for ultra-pure flu...