Abstract: In apparatus for mixing and then separating different flow streams, such as solvent extraction apparatus, a cascade of contactors and jet pumps are arranged in counter-current flow mode. The same one flow stream is applied to the drive port of each jet pump in the cascade and the other flow stream is applied to the suction port of each jet pump in the cascade. The jet pumps in the cascade increase in size from a high pressure to a low pressure end of the cascade so that the suction pressure required at successive jet pumps is reduced.

Abstract: The viability of a pack of stored blood platelets is monitored by gripping the pack between two plates (6) and (7) which are closed to pinch together the walls of the bag (10) along an L-shaped seal (14), leaving a channel (17), squeezing a part (15) of the bag by means of a reciprocating plunger (19), so that the platelets continually flow to and fro between the part (15) and the part (16), through the channel (17), and passing a beam of light from an LED (27) through the channel (17), to a photoresistor (29). The AC signal from the photoresistor corresponds to the fluctuations in the intensity of the light passing through the channel (17) and the amplitude of this signal is representative of the viability, and hence the clinical acceptability, of the platelets.