Abstract: Disclosed is a gradient proportioning valve for liquid chromatography that includes a plurality of inlet ports configured to receive a plurality of fluids, a manifold connected to each of the plurality of inlet ports configured to mix the plurality of fluids in a controlled manner to provide a fluid composition, the manifold including a plurality of conduits internal to the manifold, each of the plurality of conduits receiving fluid through a respective one of the plurality of inlet ports, an actuation mechanism having a piston located within a bored structure surrounding the piston, the actuation mechanism configured to open and close at least one of the plurality of conduits in a controlled manner where the piston and the bored structure have a tight tolerance configured to create a fluid tight seal, and a common outlet port configured to receive the fluid composition.

Abstract: A multiple-cycle engine is provided that alternates between two-cycle and four-cycle operation in response to measured engine conditions. Each piston is ball and socket mounted to allow the piston to be trained to five positions by a training block within the cylinder wall. Intake and scavenging port runners and a piston port align to place a fuel charge in the combustion chamber in the first position, while the second position seals it for compression and ignition. A piston exhaust vent aligns with an exhaust port in the third position to discharge the exhaust for completion of four-cycle operation. In a fourth position, the intake port and a second scavage port runner align to fuel the combustion chamber, while exhaust leaves through a second piston exhaust vent in alignment with the exhaust port incoming charge is scavenged by the suction of a megaphone type exhaust pipe. In a fifth position, the chamber is sealed for compression and ignition for completion of two-cycle operation.