Abstract: A sheeting is provided for use with a fluid processing cassette having a valve station with a plurality of fluid flow ports. The sheeting has a generally flexible layer and a biasing member associated with the layer. The sheeting is attached to the cassette such that the biasing member is received within the valve station. The cassette may be used with a fluid processing system having a valve actuator with a piston that is aligned with the cassette during use. In an extended position, the piston presses the sheeting against the port to prevent fluid flow through the valve station. When the piston moves from the extended position to a retracted position, it allows the sheeting to uncover the port, thereby allowing fluid flow through the valve station. The biasing member assists in displacing the sheeting from the port when the piston moves to the retracted position.

Abstract: A sheeting is provided for use with a fluid processing cassette having a valve station with a plurality of fluid flow ports. The sheeting has a generally flexible layer and a biasing member associated with the layer. The sheeting is attached to the cassette such that the biasing member is received within the valve station. The cassette may be used with a fluid processing system having a valve actuator with a piston that is aligned with the cassette during use. In an extended position, the piston presses the sheeting against the port to prevent fluid flow through the valve station. When the piston moves from the extended position to a retracted position, it allows the sheeting to uncover the port, thereby allowing fluid flow through the valve station. The biasing member assists in displacing the sheeting from the port when the piston moves to the retracted position.

Abstract: An apparatus for measuring optical density of highly absorptive materials in which a beam splitter divides light from a laser source into a reference beam, which is directed to a reference detector, and a sample beam, which is reflected off a diffusing plate, through a light limiting aperture, and to a sample. The emanations from the sample are directed to a sample detector. An instrumentation amplifier compares the intensities of the two detectors. The aperture and reference detector are positioned so that the measured intensities are equal, and the optical density of the sample is calculated.