Abstract: A device is provided comprising a piezoelectric material and at least one coating reactive with trace quantities of oxygen and/or water in reactive and inert gases. The piezoelectric material is bonded to a conductor for delivering an alternating electric current and to a conductor for transmitting resonant vibration frequency of the crystal. The reactive coating has an effective thickness which provides a serviceable life for the coating while not being so thick as to prevent vibration of the piezoelectric material.

Abstract: A process is provided for rapidly and non-destructively evaluating the particle retention characteristics of porous membranes using a novel liquid-porosimetric technique. A ratio of two membrane permeabilities is measured at preselected operating conditions using a pair of mutually immiscible fluids, one of which is employed as a membrane wetting agent and the other used as an intrusion fluid. The first operating condition, a particular transmembrane pressure, is chosen so as to selectively intrude those pores accessible to a given sized particle, such as a virus. The second operating condition, either a second preselected transmembrane pressure or a water permeability measurement, is chosen such that nearly all of the membrane pores are intruded. The ratio of the two permeabilities obtained with each set of operating conditions is thus the percentage of total flow through the membrane pores accessible to a given sized particle.

Abstract: A composite membrane and process utilizing the membrane which is capable of selectively removing particles such as viral particles from a solution such as a protein solution is provided. The membrane comprises a porous membrane substrate, a surface skin having ultrafiltration separation properties and an intermediate porous zone between the substrate and the skin which intermediate zone has an average pore size smaller than that of the substrate. The intermediate zone is free of voids which break the skin and which directly fluid communicate with the substrate. The composite is capable of a log reduction value of at least 3 (99.9% removal) of particles selectively from solution.

Abstract: A composite membrane and process utilizing the membrane which is capable of selectively removing particles such as viral particles from a solution such as a protein solution is provided. The membrane comprises a porous membrane substrate, a surface skin having ultrafiltration separation properties and an intermediate porous zone between the substrate and the skin which intermediate zone has an average pore size smaller than that of the substrate. The intermediate zone is free of voids which break the skin and which directly fluid communicate with the substrate. The composite is capable of a log reduction value of at least 3 (99.9% removal) of particles selectively from solution.

Abstract: An ultrafiltration device comprising hollow fibers or thin channels through which ultrafiltration of blood plasma is effected is operated under conditions of tangential flow and low conversion. A recirculation stream of high molecular weight fraction of the liquid stream is fed to the device and a permeate stream from the device is recovered. The optimum module aspect ratio is designed and the corresponding maximum shear rate of incoming liquid is specified and controlled so as to provide maximum separation efficiency (selectivity and flux) allowing for separation between species of similar size or molecular weight. Shear rate is controlled by controlling the recirculation stream flow rate. The ratio of the transmembrane pressure at the channel outlet to the transmembrane pressure at the channel inlet resulting from the optimal design and operation is also specified.

Abstract: A process and apparatus is provided for separating whole blood from a patient into a cellular component and a plasma component and for separating the plasma component into a high molecular weight plasma fraction and a low molecular weight plasma fraction and wherein anticoagulant is added to the whole blood and a physiologically acceptable liquid diluent is added to the plasma component. The rate of addition of the diluent is governed by the following equation: ##EQU1## called Equation 1.