Transport phenomena in zonal centrifuge rotors. II. A mathematical analysis of the areas of isodensity surfaces in reorienting gradient systems.

Zonal centrifuges may be loaded during rotation (dynamically) or at rest (statically). In the latter case, the shearing forces occurring in a liquid confined in a closed cylinder, during the transition from rest to a stable orientation in a high centrifugal force field, were examined qualitatively by evaluating the change of surfaces in each isodense layer. Analytical expressions for isodense surfaces at various levels were obtained as a function of the rotational speeds. Characteristics of the changes of each isodense layer were computed from the formula derived and are presented, in a graphical form, as figures. From these results, an optimal sample-loading location and an ideal control of acceleration or deceleration in a reorienting gradient rotor are concluded.