Sedimentation force

Sediment Volume. If the dispersion is unstable, the sediment bed will be quite deep and sedimenting particles will stick together where they first strike the sediment bed, thus forming an open stmcture with considerable occluded Hquid. If the dispersion is stable to reagglomeration, the particles will move freely past one another to avoid contact as long as possible. The result is a thin sediment bed with maximum soHds packing and minimum occluded hquid (12). Since dispersed particles setde more slowly than docs, centrifugation maybe needed to force sedimentation of small particles within a reasonable analysis time. 

This is suitable for the formulations in which the percentage of solid ingredients, suspended in liquid is to be increased. The advantage of density difference between the molten medium and suspended particles is used in this process. The concentration of heavier particles is increased in the lower part of the casing either by natural sedimentation or by forced sedimentation caused by vibrating the whole casting assembly. The sedimentation process is controlled by a number of parameters such as particle size of solid suspension, temperature of melt, period of sedimentation, viscosity of melt, concentration of solid ingredients and column of melt etc. 

Fig. 2 High resolution time series of input and output variables from the TSMs. Air and water temperature (A) and redox potential Eh (B) from duplicate TSMs over a sixteen day period. Time series of sediment pH in tidaUy-forced sediments (C) showed clear diurnal variation in response to the tides (no structured variation was observed in static systems). The light (lOh)-dark (14h) illumination cycle as detected at the sediment surface ofaTSM (D)...

When a particle in a fluid medium is subjected to a centrifugal field it experiences three forces sedimentation, buoyancy, and friction. The sedimentation force, Fs, is proportional to the particle mass, m, and to the centrifugal acceleration ... 

The stronger binding of Ca + than Na+ by chondroitin sulphate indicates that the association cannot be ascribed solely to electrostatic forces. Sedimentation coefficient and intrinsic viscosity measurements have indicated that chondroitin sulphate in solution can be represented by a semi-flexible coil with a molecular diameter of about 1.2 nm, a value which is consistent with the results of A -ray analysis. ... 

Figure 14.2 Filtration in a centrifugal field. A close relationship exists in the pressure filtration, the only difference being the forced sedimentation in the centrifugal field. The entire amount of mother phase has to filter through the entire filter cake.

Like intrinsic viscosity and diffusion, sedimentation is a frictional property. It is the transport of mass from the surface toward the bottom. In ultracentrifuge sedimentation, which is our major subject in this chapter, macromolecules in solution are forced to sediment by a centrifugal force that is 100,000 times greater than gravitational force. Sedimentation can be described by Pick s two laws with some modification, since sedimentation is often accompanied by diffusion. The modified equation of Pick s first law is... 

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