A valve mechanism which is resiliently biassed towards a first position but is normally retained in a second position by means of a linkage including a chemically sensitive device which is arranged to release in the presence of a contaminant. Participating individuals apply and are approved and are issued a card with an identifiable account number using credit approval systems. In particular, the photon energy, time of event, and location of the detection instrument at the time of detection is recorded for real time transmission to a central data collectionanalysis system. An outer piston assembly includes a pair of pistons, one each operatively located in a respective one of the engine cylinders, with at least one pull rod connected between the outer pistons. The extent of the change in volume of the composition can be precisely controlled by factors such as the density of the ECM, the density of the living cells, the timing for interaction and the serum concentration. Such liquid-phase oxidation is carried out in a bubble column reactor that provides for a highly efficient reaction at relatively low temperatures.