Abstract: A bubble valve that comprises a liquid delivery channel and a localized heating arrangement. The liquid delivery channel includes an upstream portion and a constriction downstream of the upstream portion. The constriction has a smaller cross-sectional area than the upstream portion. The localized heating arrangement is located in the liquid delivery channel and generates heat to nucleate and enlarge a bubble in the liquid. The constriction is shaped to form a seal with the bubble. The localized heating arrangement additionally generates heat to move the bubble relative to the constriction to control the flow of the liquid. A pressure regulator that comprises a liquid delivery channel connected to a liquid outlet, a sensor located adjacent the liquid outlet, a controller that operates in response to the sensor and a localized heating arrangement. The liquid delivery channel includes an upstream portion, and a constriction located between the upstream portion and the liquid outlet.

Abstract: A pressure regulator that sets the pressure of a liquid to a predetermined pressure differential below a reference pressure, such as atmospheric pressure. The pressure regulator comprises a liquid delivery channel and a capillary array. The liquid delivery channel includes a liquid input and a liquid output. The liquid flows through the liquid delivery channel from the liquid input to the liquid output. The capillary array is composed of ones of an elongate capillary. The capillary includes a first end in fluid communication with the liquid delivery channel and a second end in pressure communication with a source of the reference pressure. The liquid flows through the first end into the capillary to form a liquid surface in the capillary. The second end is remote from the first end.

Abstract: An apparatus for diluting a sample with a diluent, comprising a fixed volume measuring chamber, a fixed volume receiving chamber and fluid receiving relationship to the measuring chamber, a gas vent in the receiving chamber, a stop flow junction between the measuring chamber and the receiving chamber, a sample application site in fluid donating relationship to the measuring chamber, wherein the vertical height difference between the sample application site and the stop flow junction is insufficient to provide a hydrostatic pressure capable of overcoming backpressure at the stop flow junction when sample is applied to the sample application site, and the diluent application site and fluid donating relationship to the measuring chamber. Sample and diluent are added sequentially to the apparatus of the invention without requiring any intervening operations. Various means are provided for restarting flow, which causes diluent to wash the sample into the receiving chamber, where the two can be mixed.

Abstract: An apparatus for diluting a sample with a diluent, comprising a fixed volume measuring chamber, a fixed volume receiving chamber and fluid receiving relationship to the measuring chamber, a gas vent in the receiving chamber, a stop flow junction between the measuring chamber and the receiving chamber, a sample application site in fluid donating relationship to the measuring chamber, wherein the vertical height difference between the sample application site and the stop flow junction is insufficient to provide a hydrostatic pressure capable of overcoming backpressure at the stop flow junction when sample is applied to the sample application site, and the diluent application site and fluid donating relationship to the measuring chamber. Sample and diluent are added sequentially to the apparatus of the invention without requiring any intervening operations. Various means are provided for restarting flow, which causes diluent to wash the sample into the receiving chamber, where the two can be mixed.

Abstract: Hollow fiber reactors for growing microbial cells. Isotropic hollow fibers are supported in a housing inoculated with cells. Nutrient medium passing through the lumen undergoes a pressure drop resulting in radial convective flow: the nutrient medium flows outwardly from the lumen into the surrounding area adjacent the entry port and fluid surrounding the hollow fiber flows into the lumen adjacent the exit port. With the efficient distribution of nutrients and removal of product, high cell densities are achieved providing for high product yields per unit reactor volume.

Abstract: Methods for microbiological processing of organic materials for production of valuable products. Asymmetric hollow fibers are employed in a flow reactor, where the hollow fibers have a semipermeable membrane surrounding a lumen, where the semipermeable membrane is supported by a sponge structure. The pores of the sponge structure serve as a housing for microorganisms or cells with high density packing of the microorganisms or cells in the pores. Nutrient medium continuously flowing through the lumen provides nutrients to the microorganisms or cells as well as any substrates to be processed by the microorganisms or cells. The nutrients and substrates diffuse through the semipermeable membrane into the pores, where they are processed, and the metabolic products diffuse into the lumen. The lumen effluent is then processed for the desired products. Optionally, oxygen is provided external to the hollow fiber to enhance the amount of oxygen available to the microorganisms and cells.