The differential migration of ions in an applied electric field is the basis for separation of chemical species by capillary electrophoresis. Axial diffusion of the concentration peak limits the separation efficiency. Electromigration dispersion is observed when the concentration of sample ions is comparable to that of the background ions. Under such conditions, the local electrical conductivity is significantly altered in the sample zone making the electric field, and therefore, the ion migration velocity concentration dependent. The resulting nonlinear wave exhibits shock like features, and, under certain simplifying assumptions, is described by Burgers' equation (S. Ghosal and Z. Chen Bull. Math. Biol. 201072, pg. 2047). In this paper, we consider the more general situation where the walls of the separation channel may have a non-zero zeta potential and are therefore able to sustain an electro-osmotic bulk flow. The main result is a one dimensional nonlinear advection diffusion equation for the area averaged concentration. This homogenized equation accounts for the Taylor-Aris dispersion resulting from the variation in the electro-osmotic slip velocity along the wall. It is shown that in a certain range of parameters, the electro-osmotic flow can actually reduce the total dispersion by delaying the formation of a concentration shock. However, if the electro-osmotic flow is sufficiently high, the total dispersion is increased because of the Taylor-Aris contribution.
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http://dx.doi.org/10.1017/jfm.2012.76 | DOI Listing |
ACS Nano
January 2025
Adolphe Merkle Institute, University of Fribourg, Fribourg 1700, Switzerland.
Biological nanopores offer a promising approach for single-molecule analysis of nucleic acids, peptides, and proteins. The work presented here introduces a biological nanopore formed by the self-assembly of complement component 9 (C9). This exceptionally large and cylindrical protein pore is composed of 20 ± 4 monomers of C9 resulting in a diameter of 10 ± 4 nm and an effective pore length of 13 nm.
View Article and Find Full Text PDFAnal Chim Acta
February 2025
School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao, 066004, PR China; Hebei Key Laboratory of Micro-Nano Precision Optical Sensing and Measurement Technology, Qinhuangdao, 066004, PR China. Electronic address:
Background: Fractionation of microalgal cells has important applications in producing pharmaceuticals and treating diseases. Multiple types of microalgal cells generally coexist in the oceans or lakes and are easily contaminated by microplastics and bacteria. Therefore, it is of paramount significance to develop an effective fractionation approach for microalgal cells for biological applications.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, People's Republic of China.
Efficient capture of single-stranded DNA (ssDNA) is crucial for high-throughput sequencing, which influences the speed and accuracy of genetic analysis. Electrophoresis (EP) and electro-osmotic flow (EOF) have a significant impact on the translocation behavior of ssDNA through the nanopore. Experimentally, dynamically tracking these two effects remains challenging, and conventional numerical methods also struggle to capture their dynamic properties in the presence of DNA.
View Article and Find Full Text PDFJ Chem Phys
November 2024
"Glass and Time," IMFUFA, Department of Science and Environment, Roskilde University, Roskilde 4000, Denmark.
J Biomech Eng
January 2025
Department of Mathematics, COMSATS University Islamabad, Park Road Tarlai Kalan, Islamabad 45550, Pakistan.
The dynamics of electro-osmotically generated flow of biological viscoelastic fluid in a cylindrical geometry are investigated in this paper. This flux is the result of walls contracting and relaxing sinusoidally in a magnetic environment. The blood's viscoelasticity and shear-thinning viscosity are the primary causes of its non-Newtonian characteristics.
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