Continuous Free-Film Electrophoresis: The Crescent Phenomenon

Strickler, Allen; Sacks, T.

doi:10.1080/00327487308061511

Cited by 23 publications

(10 citation statements)

References 4 publications

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“…In the case of the gravity modulation the results obtained by the matrix method are very close to those given by the asymptotic relation for co -> oo. Figures 9a and 9b show the variation of alteration factor values given, respectively, by the direct method used in this chapter and by an asymptotic analysis given by relation (83). A perfect agreement is observed for the axisymmetric case at which the study is restricted, as well in the case of perfectly conducting walls as in that of insulating walls, from a nondimensional frequency co'^40.…”

Section: Case Of a Bounded Cylindersupporting

confidence: 50%

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Low-Gravity Fluid Dynamics and Transport Phenomena

Koster¹,

Sani²

1990

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Section: Case Of a Bounded Cylindersupporting

confidence: 50%

“…This effect tends toward 0, when co -»oo, as for the case of an infinite cylinder. This can be easily explained by the asymptotic relation (83). Indeed, as a result of the particular form of the operator N, the matrix product N 2 -NM 0 N does not depend on RQ and thus does not depend on co.…”

Section: Case Of a Bounded Cylindermentioning

confidence: 95%

Low-Gravity Fluid Dynamics and Transport Phenomena

Koster¹,

Sani²

1990

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“…These counter-rotating vortices "scour" the walls of the annulus and dramatically improve radial heat and mass transfer without significantly increasing global axial dispersion. This "scouring" action is particularly important in ameliorating "crescent" dispersion [33,34] due to axial electroosmotic flows. In addition, the vortices interrupt the radial temperature gradient which would otherwise drive a persistent and deleterious bulk natural convection.…”

Section: Theorymentioning

confidence: 99%

“…It is well-known that electroosmotically induced "crescent" distortion [33] is often the primary source of sample band spreading in "thin-film" electrophoresis chambers [3,19,34]. This form of dispersion is particularly troublesome because, unlike diffusion which increases sample band width with ffiffi t p , crescent dispersion increases sample band width at a faster rate, i.e., in direct proportion to t. Without Taylor vortices, the same type of dispersion would occur in the electrophoretic annulus.…”

Section: Mass Transfermentioning

confidence: 99%

Preparative free‐flow electrofocusing in a vortex‐stabilized annulus

Ivory¹

2004

Electrophoresis

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This paper describes the development of an annular chamber designed for preparative free-flow electrophoresis which can operate at voltages up to 20 kV, electric fields up to 65 kV/m, and power densities as high as 10 MW/m(3). This apparatus uses counter-rotating fluid vortices to stabilize the aqueous medium in the annulus against natural convection while improving heat and mass transfer over vortex-free Couette flow. The vortices are generated by rotating the inner surface of the annulus and, if the rotor and stator have complementary shapes, dispersion induced by electrokinetic and electrohydrodynamic flows can be mitigated even at the highest operating voltages. Following a brief overview of contemporary annular free-flow instrumentation, the theoretical principles for momentum and heat transport in the vortices are discussed in some detail and then the results of several electrofocusing experiments are provided to illustrate the resolving power of this instrument.

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“…In continuous flow electrophoresis, electroosmotic flow perpendicular to the main direction of liquid flow causes the electrophoretically separated bands to assume crescent-shaped cross sections which, according to the electrophoretic mobilities, are either concave or convex with respect to the anode (20). It is, however, possible to have one of the electrophoretic fractions migrate as a flat band so that that fraction can be collected with optimum purity (21).…”

Section: Effects Of Electroosmosis In Continuous Flow Electrophoresismentioning

confidence: 98%

Electrokinetic Cell Separation

Oss

1975

Separation Science

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Particles of the size of living cells are too big to be separated in stabilizing media such as gels. The separation thus has to be done while they are freely suspended in a buffer contained in a vessel of appropriate shape. The major two disturbing factors under these conditions are cell sedimentation and electroosmotic backflow along the walls of the vessel.Cell Jedimentation can be overcome (a) by measuring very small cell transport paths, along which the cells have no time to sediment, using a microscope; (b) by applying a continuous liquid flaw perpendicular to the direction of separation; (c) by stabilizing the cells in a density gradient; (d) by ascending electrophoresis, in the direction opposite to that of gravity; (e) by using a column packed with beads of a homogeneous size; and (f) by doing the separation at zero gravity, in outer space.Electyoosmotic backflow. This can (a) be overcome by coating the vessel-walls with a material of 0 [ potential; and (b) be managed by forcing it into a completely uniform flow by coating the vessel walls with a material of non zero [-potential and by providing both ends of the vessel with porous plugs made of the same material.

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Continuous Free-Film Electrophoresis: The Crescent Phenomenon

Cited by 23 publications

References 4 publications

Low-Gravity Fluid Dynamics and Transport Phenomena

Low-Gravity Fluid Dynamics and Transport Phenomena

Preparative free‐flow electrofocusing in a vortex‐stabilized annulus

Electrokinetic Cell Separation

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