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The sedimentation coefficient is typically dependent on the concentration of the solute (i.e. a macromolecular solute such as a protein). Despite 80+ years of study, there is not yet a consensus on the way to perfectly model this relationship while also taking into account all possible non-ideal terms to account for the diverse possible sizes, shapes, and densities of molecular solutes. [2]
A laboratory ultracentrifuge. In chemistry, a Svedberg unit or svedberg (symbol S, sometimes Sv [a]) is a non-SI metric unit for sedimentation coefficients.The Svedberg unit offers a measure of a particle's size indirectly based on its sedimentation rate under acceleration (i.e. how fast a particle of given size and shape settles out of suspension). [1]
It can be used to estimate the time (in hours) required for sedimentation of a fraction with a known sedimentation coefficient (in svedbergs): t = k s {\displaystyle t={\frac {k}{s}}} The value of the clearing factor depends on the maximum angular velocity ω {\displaystyle \omega } of a centrifuge (in rad/s) and the minimum and maximum radius ...
The erythrocyte sedimentation rate (ESR or sed rate) is the rate at which red blood cells in anticoagulated whole blood descend in a standardized tube over a period of one hour. It is a common hematology test, and is a non-specific measure of inflammation .
The rate of sedimentation is the thickness of sediment accumulated per unit time. [8] For suspended load, this can be expressed mathematically by the Exner equation. [9] Rates of sedimentation vary from less than 3 millimeters (0.12 in) per thousand years for pelagic sediment to several meters per thousand years in portions of major river deltas.
where t is the time, c is the solute concentration (moles per unit length in the z-direction), and the parameters D, s, and g represent the solute diffusion constant, sedimentation coefficient and the (presumed constant) acceleration of gravity, respectively. The Mason–Weaver equation is complemented by the boundary conditions
The first and second terms on the right-hand side of the Lamm equation are proportional to D and sω 2, respectively, and describe the competing processes of diffusion and sedimentation. Whereas sedimentation seeks to concentrate the solute near the outer radius of the cell, diffusion seeks to equalize the solute concentration throughout the cell.
Sedimentation rate may refer to: Sedimentation rate of particles in a liquid, described by Stokes' law; Erythrocyte sedimentation rate, a medical test for inflammation; Rate of sedimentation (geology), thickness of sediment accumulated per unit time