This is why uranium has to be enriched by the complicated process of centrifugation.
Any of several methods gaseous diffusion, gas centrifugation, liquid thermal diffusion can be employed to separate and concentrate the fissile uranium-235 isotope into several grades, from low-enrichment (2 to 3 percent uranium-235) to fully enriched (97 to 99 percent uranium-235).
The more important particle separation methods are filtration, sedimentation, elutriation, centrifugation, particle electrophoresis, electrostatic precipitation, flotation, and screening, which are described in a later section.
Milk fat, being less dense than other milk components, can be efficiently removed in a cream separator by centrifugation, yielding low-fat milk and skim milk.
Centrifugation can be used to separate the plasma or serum from blood samples.
(A new technique, density-gradient centrifugation, could be used to separate such molecules by weight.) On heating, this DNA separated into half heavy and half light strands.
The isolation of nanoparticles from colloidal and larger matter involves specialized techniques, such as ultra centrifugation and field-flow fractionation.
The precipitate can then be physically separated from the mixture by filtration or centrifugation.
It is thus possible to obtain fractions containing predominantly one type of organelle: nuclei (and some unbroken cells); mitochondria, lysosomes, and microbodies; microsomes (i.e., ribosomes and endoplasmic reticulum fragments); and after prolonged centrifugation at forces in excess of 100,000 times gravity a clear liquid that represents the soluble fraction of the cytoplasm.
From the foregoing discussion, it is clear that a practically complete separation of the suspending medium and the suspended particles can be produced if the centrifugation is allowed to continue until all particles have collected against the outer wall of the spinning vessel or centrifuge.
It should also be noted that a partial separation of two groups of suspended particles of different size can be effected by allowing centrifugation to continue only long enough for all of the larger particles to be completely packed into the sediment, since then many of the small particles will still be suspended in the fluid.
