Electrophoretic Velocity, Νep

1. Filterability (deformability) of erythrocytes of patients with Raynaud's phenomenon together with progressive systemic sclerosis (PSS) was decreased compared with the filtration of erythrocytes from normal subjects. 2. PSS erythrocytes showed lower electrophoretic velocity and about 23% less neuraminidase-removable sialic acid density on their surface than the normal erythrocytes. 3. PSS erythrocytes showed more adherence to cultured endothelial cells than the control normal erythrocytes. 4. It is concluded that the increased rigidity and adherence of PSS erythrocytes-5-have pathological significance in the mechanism of vascular abnormalities in PSS.

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Modeling of Electro-Kinetic Motion of Janus Droplet

ASME 2017 15th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2017-5501 ◽

2017 ◽

Author(s):

S. Doğan Öner ◽

Barbaros Çetin

Keyword(s):

Boundary Element ◽

Spherical Particles ◽

Janus Particles ◽

Element Formulation ◽

Current Formulation ◽

Fundamental Understanding ◽

Electrophoretic Velocity ◽

Janus Droplet ◽

Further Development ◽

Wall Interactions

Electro-kinetic manipulation Janus particles and droplets has attracted attention in recent years due to their potential application in microfluidics. Due to the presence of two different zone on the surface of particles with different charge distribution, the motion of the Janus particles are quite different than the that of regular particles. Therefore; the fundamental understanding of this motion is the key element for the further development of the microfluidic systems with Janus particles. In present study, electro-kinetic motion of Janus droplets inside a micro-channel is modeled using boundary element formulation. 2D formulation is verified against the reported experimental data in the literature. Results show that the 2D boundary element formulation is successful for the prediction of the electrophoretic velocity of the Janus droplets. The current formulation has a potential to model non-spherical particles and to study particle-particle and particle-wall interactions.

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Electrophoretic characteristics of ram and rabbit spermatozoa

Proceedings of the Royal Society of London Series B Biological Sciences ◽

10.1098/rspb.1961.0072 ◽

1961 ◽

Vol 155 (959) ◽

pp. 292-305 ◽

Cited By ~ 16

Keyword(s):

Electric Field ◽

Swimming Speed ◽

Salt Concentration ◽

High Salt ◽

Ion Concentration ◽

Ground Speed ◽

Constant Ph ◽

Electrophoretic Velocity ◽

Low Ionic Strength ◽

Rabbit Spermatozoa

1. The influence of a d. c. electric field on the direction in which ram and rabbit spermatozoa swim has been investigated. The magnitude of the electrophoretic component is so small in the presence of high salt concentrations ( μ = 0.1) that it plays no part in controlling the direction in which the spermatozoa swim. A significant electrophoretic velocity component can, however, be imposed if the spermatozoa are suspended in a diluent (277 mM-fructose) with a low ionic strength ( μ < 0.01). In this condition higher field strengths can be applied without any concomitant rise in temperature, and the ζ-potential increases because the gegen-ion concentration is reduced. 2. In a diluent containing 277 mM-fructose and 10 mM-NaCl two types of spermatozoa are seen when the electric field is applied. Their orientation depends on whether they carry a net negative charge in the region of their heads or their tails. 'Head-anode' spermatozoa swim with unusual rapidity towards the anode but immediately decelerate when the field is switched off. ‘Tail-anode' spermatozoa have a variable ground speed and may, if the field strength is high, be seen swimming tail first towards the anode. They accelerate away from the anode when the field is switched off. 3. The proportions of the two types of spermatozoa vary with salt concentration at constant pH, and with pH at constant salt (10 mM-NaCl) concentration. 4. If the swimming speed of spermatozoa is reduced by cooling, electrophoresis in the presence of high salt concentration ( μ = 0.1) differentiates spermatozoa into two kinds in another way. Both are oriented with their tails pointing towards the anode (tail-anode), but their net ground speed may vary in magnitude and direction according to their inherent swimming speed. Complete immobilization of the spermatozoa resulted in a uniform electrophoretic migration towards the anode, tail first, at all pH’s above 3.5. 5. The implications of these findings are discussed with respect to sperm phenotypes and their possible electrophoretic separation.

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In Situ Fluorescence Microscopic Investigation into the Dependence of Conformation and Electrophoretic Velocity of Single DNA Molecules on Acid or Spermidine Concentration

Analytical Sciences ◽

10.2116/analsci.25.293 ◽

2009 ◽

Vol 25 (2) ◽

pp. 293-299 ◽

Cited By ~ 4

Author(s):

Shohei INOSHITA ◽

Satoshi TSUKAHARA ◽

Terufumi FUJIWARA

Keyword(s):

Microscopic Investigation ◽

Dna Molecules ◽

Single Dna Molecules ◽

Electrophoretic Velocity

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Strong-field electrophoresis

Journal of Fluid Mechanics ◽

10.1017/jfm.2012.161 ◽

2012 ◽

Vol 701 ◽

pp. 333-351 ◽

Cited By ~ 22

Author(s):

Ory Schnitzer ◽

Ehud Yariv

Keyword(s):

Electric Field ◽

Electric Fields ◽

Double Layer ◽

Strong Field ◽

Salt Flux ◽

Large Reynolds Number ◽

Diffuse Part ◽

Electrophoretic Velocity ◽

Diffusive Boundary ◽

Diffusive Fluxes

AbstractWe analyse particle electrophoresis in the thin-double-layer limit for asymptotically large applied electric fields. Specifically, we consider fields scaling as ${\delta }^{\ensuremath{-} 1} $, $\delta ~(\ll \hspace *{-2pt}1)$ being the dimensionless Debye thickness. The dominant advection associated with the intense flow mandates a uniform salt concentration in the electro-neutral bulk. The $O({\delta }^{\ensuremath{-} 1} )$ large tangential fields in the diffuse part of the double layer give rise to a novel ‘surface conduction’ mechanism at moderate zeta potentials, where the Dukhin number is vanishingly small. The ensuing $O(1)$ electric current emerging from the double layer modifies the bulk electric field; the comparable $O(1)$ transverse salt flux, on the other hand, is incompatible with the nil diffusive fluxes at the homogeneous bulk. This contradiction is resolved by identifying the emergence of a diffusive boundary layer of $O({\delta }^{1/ 2} )$ thickness, resembling thermal boundary layers at large-Reynolds-number flows. The modified electric field within the bulk gives rise to an irrotational flow, resembling those in moderate-field electrophoresis. At leading order, the particle electrophoretic velocity is provided by Smoluchowski’s formula, describing linear variation with applied field.

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Nonlinear electrophoresis of a tightly fitting sphere in a cylindrical tube

Journal of Fluid Mechanics ◽

10.1017/jfm.2018.212 ◽

2018 ◽

Vol 843 ◽

pp. 847-871 ◽

Cited By ~ 1

Author(s):

J. D. Sherwood ◽

S. Ghosal

Keyword(s):

Zeta Potential ◽

Field Strength ◽

Surface Charge ◽

Cylindrical Tube ◽

Ionic Concentration ◽

Charge Densities ◽

Low Field ◽

Counter Ions ◽

Ion Exclusion ◽

Electrophoretic Velocity

We investigate electrophoresis of a tightly fitting sphere of radius $R-h_{0}$ on the axis of a circular tube of radius $R$, using lubrication theory and ideas due to Schnitzer & Yariv (Phys. Fluids, vol. 26, 2014, 122002). The electrical charge clouds on both the cylindrical wall and the surface of the sphere are assumed thin compared to the gap between the sphere and cylinder, so that charge clouds do not overlap and ion exclusion effects are minimal. Nevertheless, non-uniform pumping of counter-ions within the charge clouds leads to a change in the ionic concentration outside the charge clouds in the narrow gap between sphere and cylinder. The electro-osmotic slip velocities at the two surfaces are modified, leading to a decrease in the electrophoretic velocity of the sphere at low Péclet numbers and an increase in the velocity at high Péclet numbers. When the field strength $E_{0}$ is low, it is known that the electrophoretic velocity $U_{0}$ is proportional to $E_{0}(\unicode[STIX]{x1D701}_{s}-\unicode[STIX]{x1D701}_{c})$ which is zero when the zeta potential $\unicode[STIX]{x1D701}_{s}$ on the sphere surface is equal to the zeta potential $\unicode[STIX]{x1D701}_{c}$ on the cylinder. The perturbation to the above low field strength electrophoretic velocity (at high Péclet number) is predicted to be proportional to $E_{0}^{3}(\unicode[STIX]{x1D701}_{s}+\unicode[STIX]{x1D701}_{c})^{2}(\unicode[STIX]{x1D70E}_{s}+\unicode[STIX]{x1D70E}_{c})$, where $\unicode[STIX]{x1D70E}_{s}$ and $\unicode[STIX]{x1D70E}_{c}$ are the surface charge densities on the sphere and cylinder. The choice of materials with similar or identical zeta potentials (and surface charge densities) for the cylinder and sphere should therefore facilitate the observation of velocities nonlinear in the field strength $E_{0}$, since the reference linear electrophoretic velocity will be small.

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Electrophoresis of tightly fitting spheres along a circular cylinder of finite length

Journal of Fluid Mechanics ◽

10.1017/jfm.2021.892 ◽

2021 ◽

Vol 929 ◽

Author(s):

J.D. Sherwood ◽

S. Ghosal

Keyword(s):

Circular Cylinder ◽

Finite Length ◽

Pressure Difference ◽

Debye Length ◽

Surface Conductivity ◽

Solid Surfaces ◽

Zeta Potentials ◽

Electrophoretic Velocity ◽

Gap Width ◽

Analytic Prediction

Electrophoresis of a tightly fitting sphere of radius $a$ along the centreline of a liquid-filled circular cylinder of radius $R$ is studied for a gap width $h_0=R-a\ll a$ . We assume a Debye length $\kappa ^{-1}\ll h_0$ , so that surface conductivity is negligible for zeta potentials typically seen in experiments, and the Smoluchowski slip velocity is imposed as a boundary condition at the solid surfaces. The pressure difference between the front and rear of the sphere is determined. If the cylinder has finite length $L$ , this pressure difference causes an additional volumetric flow of liquid along the cylinder, increasing the electrophoretic velocity of the sphere, and an analytic prediction for this increase is found when $L\gg R$ . If $N$ identical, well-spaced spheres are present, the electrophoretic velocity of the spheres increases with $N$ , in agreement with the experiments of Misiunas & Keyser (Phys. Rev. Lett., vol. 122, 2019, 214501).

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