Centrifugation high-speed

Particles that are smaller and less dense than the nuclei can be obtained by step-by-step acceleration of the gravity on the supernatant left over from the first centrifugation. However, this requires very powerful centrifuges (high-speed centrifuges and ultracentrifuges). The sequence in which the fractions are obtained is mitochondria, membrane vesicles, and ribosomes. Finally, the supernatant from the last centrifugation contains the cytosol with the cell s soluble components, in addition to the buffer. 

Refrigerated centrifuge (high speed) with rotors (up to 12,000 ) adapted to Eppendorf and Falcon (15-50 mL) tubes. 

There are three major types of centrifuge commonly encountered in laboratory settings namely low-speed (clinical) centrifuge, high-speed centrifuge and ultracentrifuge. These have different characteristics and applications, which are briefly considered below. 

Anotlier standard metliod is to use a (high-speed) centrifuge to sediment tire colloids, replace tire supernatant and redisperse tire particles. Provided tire particles are well stabilized in tire solvent, tliis allows for a rigorous purification. Larger objects, such as particle aggregates, can be fractionated off because tliey settle first. A tliird metliod is (ultra)filtration, whereby larger impurities can be retained, particularly using membrane filters witli accurately defined pore sizes. 

Centrifugal casting is used to produce water softener tanks and pipe by saturating a reinforcement with thermosetting resin within a mold that is then rotated at high speed to consoHdate the laminate before curing. 

These simple velocity profiles do not indicate directly any dependence of the flow pattern efficiency upon the rotational speed of the centrifuge. A dependence on speed is to be expected on the basis of the argument that at high speeds the gas in the centrifuge is crowded toward the periphery of the rotor and that the effective distance between the countercurrent streams is thereby reduced. It can be seen from the two-sheU model that, as the position of upflowing stream approaches the periphery, the flow pattern efficiency drops off from its maximum value. 

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