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Parallel production of gradients in vertical rotors
Despite the popularity of tube-format density gradient centrifugation and the increase in the numbers of tubes that may be accommodated by the newer rotors available, the problem still persists of efficiently producing identical density gradients for each tube position. This problem has been compounded with the emergence of "vertical tube rotors" - the most recent development and innovation in centrifugal methodology. A number of solutions have been proposed to attack the problem of multiple gradient production and several of these are examined and evaluated in this work. Most successful and particularly useful is an approach in which a system of plungers incorporated into the design of a vertical tube rotor is used to apportion a single stream of gradient among the rotor's chambers. A similar approach is taken to empty (either in concert or in sequence) the gradient (and separated particles) when centrifugation is completed. The apparatus produces gradients in short order and with exceptional uniformity. Rotor performance was analyzed using biological and model test systems.