Sir Samuel Garth, F. R. S.: The dispensary poet

Booth, Catherine

doi:10.1098/rsnr.1986.0008

Cited by 16 publications

(28 citation statements)

References 2 publications

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“…This figure doubles for a divalent ion and raises doubts about ignoring higher order effects under these conditions. There is a long established alternative to the OFP approach that is grounded on very similar continuum electro-hydrodynamic principles, but has its origin in the electrophoresis of large colloidal particles [27][28][29][30][31]. In this approach, the translational Brownian motion of the guest ion is ignored.…”

Section: The Relaxation Effectmentioning

confidence: 99%

“…Both of these effects have to do with the influence of the ionic atmosphere of the guest ion on its electrophoretic mobility. The electrophoretic effect is related to the hydrodynamic backflow the ion atmosphere generates at the surface of the guest ion [24][25][26] and the relaxation effect concerns the effect of the distortion of the ion atmosphere from its equilibrium distribution on electrophoretic mobility [22,23,[27][28][29][30][31]. A discussion of the relaxation effect, which is a very complex problem, shall be postponed to Section 2.2 so that we may focus on the electrophoretic effect and the effect of particle shape and charge distribution in this subsection.…”

Section: Electrophoretic Mobility Of a Single Guest Ion In The Absencmentioning

confidence: 99%

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The dependence of the electrophoretic mobility of small organic ions on ionic strength and complex formation

et al. 2010

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The ionic strength dependence of the electrophoretic mobility of small organic anions with valencies up to -3 is investigated in this study. Provided the anions are not too aspherical, it is argued that shape and charge distribution have little influence on mobility. To a good approximation, the electrophoretic mobility of a small particle should be equal to that of a model sphere with the same hydrodynamic radius and same net charge. For small ions, the relaxation effect (distortion of the ion atmosphere from equilibrium due to external electric and flow fields) is significant even for monovalent ions. Alternative procedures of accounting for the relaxation effect are examined. In order to account for the ionic strength dependence of a specific set of nonaromatic and aromatic anions in aqueous solution, it is necessary to include complex formation between the anion with species in the BGE. A number of possible complexes are considered. When the BGE is Tris-acetate, the most important of these involves the complex formed between anion and Tris, the principle cation in the BGE. When the BGE is sodium borate, an anion-anion (borate) complex appears to be important, at least when the organic anion is monovalent. An algorithm is developed to analyze the ionic strength dependence of the electrophoretic mobility. This algorithm is applied to two sets of organic anions from two independent research groups.

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Section: The Relaxation Effectmentioning

confidence: 99%

Section: Electrophoretic Mobility Of a Single Guest Ion In The Absencmentioning

confidence: 99%

The dependence of the electrophoretic mobility of small organic ions on ionic strength and complex formation

et al. 2010

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“…The point of departure is the same standard electro-kinetic equations for the ion concentrations and electric potential as used in the above mentioned references. For completeness, and to clearly state the approximations, the derivation of these wellknown equations (see, for example, [11][12][13][14] ) is briefly discussed in subsection V A. The solution of the equations of motion, and the resulting expression for the attenuation factor and the phase shift will be presented in subsection V B.…”

Section: Electrode Polarizationmentioning

confidence: 99%

“…This equation of motion is the one-dimensional form of a wellknown electro-kinetic equation in the absence of electro-osmotic flow, which plays no role in the present plate geometry (see, for example, [11][12][13][14] ). The boundary condition for the potential between the electrodes reads,…”

Section: A the Basic Equationsmentioning

confidence: 99%

Electric-field induced transitions in suspensions of charged colloidal rods

Kang

Dhont

2010

Soft Matter

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We explore transitions in suspensions of fd virus at a low ionic strength, induced by external electric fields at frequencies where double layers are polarized. On the basis of the different optical morphologies, phase/state diagrams are constructed in the field-amplitude versus frequency plane and the field-amplitude versus concentration plane. Due to interactions between polarized double layers, for low frequencies, various phases and dynamical states are found: a nematic phase, a striped phase and a dynamical state where nematic domains melt and reform. At relatively high frequencies of a few kHz, a uniform homeotropic phase is induced. The various phases and states are characterized by means of polarization microscopy, birefringence, dynamic light scattering and video-correlation spectroscopy. An expression is derived for the attenuation of the electric field due to electrode polarization, which is tested experimentally. This theory is used to correct phase/state diagrams for electrode polarization.

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“…In addition to accounting for detailed shape and charge distribution, account can be taken of "ion relaxation", which refers to the distortion of the local ion distribution from equilibrium due to the presence of an external electric or flow field. 22,23 This effect is important for highly charged macroions including certain portions of the charge ladders of proteins. All of the models and methodologies discussed above are grounded on the continuum primitive model (CPM).…”

Section: Introductionmentioning

confidence: 99%

Electrophoresis of Protein Charge Ladders: A Comparison of Experiment with Various Continuum Primitive Models

et al. 2004

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Detailed modeling of the free solution electrophoresis of five proteins (bovine R-lactalbumin, hen egg white lysozyme, bovine superoxide dismutase, human carbonic anhydrase II, and hen ovalbumin) is carried out within the framework of the continuum primitive model. Protein crystal structures and translational diffusion constants are used to design and parametrize the models. The modeling results are compared with experimental mobilities of protein charge ladders, collections of protein derivatives where the number of charge groups is varied by partial acylation of lysine residues or by amidation of glutamic and aspartic acid residues. The simplest model considered is the Yoon and Kim model of a prolate/oblate ellipsoid with uniform surface potential, electrostatics treated at the level of the linear Poisson-Boltzmann equation, and distortion of the ion atmosphere from equilibrium (ion relaxation) ignored (Yoon, B. J.; Kim, S. J. Colloid Interface Sci. 1989, 128, 275). This model provides good agreement with experiment but only if the net absolute protein charge is low or the average absolute surface, or , potential is less than ∼25 mV. Boundary element (BE) modeling is also carried out in which detailed surface models are employed and the electrostatics are solved at the level of the nonlinear Poisson-Boltzmann equation. Ion relaxation is also included in some of the BE studies. All of the experimental mobilities are in good (human carbonic anhydrase II and hen ovalbumin) to excellent (bovine R-lactalbumin, hen egg white lysozyme, and bovine superoxide dismutase) agreement with BE modeling that includes ion relaxation. We believe that these results taken as a whole serve to confirm the ability of the continuum primitive model to predict, with quantitative accuracy, the free solution electrophoretic mobilities of proteins, provided the underlying models are sufficiently realistic. When a discrepancy occurs, it may be due to error in modeling either the protein charge or the solution conformation. The models described in this work also provide a useful approach for determining values of ∆Z, the change in net charge of proteins due to the chemical modification of charged groups. Knowledge of ∆Z is essential for the use of protein charge ladders in the quantitative description of the electrostatic properties and interactions of proteins. This paper supports the view that the continuum primitive model may be more appropriate for the modeling of electrokinetics than for electrostatics. The main challenge to the accurate predictions of electrophoretic mobilities may lie primarily in the modeling of electrostatics, not electrokinetics.

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Sir Samuel Garth, F. R. S.: The dispensary poet

Cited by 16 publications

References 2 publications

The dependence of the electrophoretic mobility of small organic ions on ionic strength and complex formation

The dependence of the electrophoretic mobility of small organic ions on ionic strength and complex formation

Electric-field induced transitions in suspensions of charged colloidal rods

Electrophoresis of Protein Charge Ladders: A Comparison of Experiment with Various Continuum Primitive Models

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