Field gradient electrophoresis

A clear distinction between electrophoresis (field acdion on an object carrying excess free charges) and dielectrophoresis (field gradient acdion on neutral objects) must be borne in mind at all times. 

Advances in experimental techniques, including pulsed-field gradient NMR, and theoretical methods, including volume averaging, macrotransport, and variational methods, that may lead to the resolution of a number of the fundamental issues in gel electrophoresis and to improvements in the practical application of electrotransport in polymeric media... 

For capillary zone electrophoresis (CZE) mass spectrometry coupling, another modification of an ESI interface has been developed. This interface uses a sheath flow of liquid to make the electrical contact at the CZE terminus, thus defining both the CZE and electrospray field gradients. This way, the composition of the electro sprayed liquid can be controlled independently of the CZE buffer, thereby providing operation with buffers that could not be used previously, e.g., aqueous and high ionic strength buffers. In addition, the interface operation becomes independent of the CZE flow rate. [62]... 

Studies incorporating NMR detection in electrophoresis began in 1972 when Packer and coworkers examined MeaN" " ions under the influence of an electric current [89]. They determined that electrical current density in the sample and the radial motion of ions under the influence of the magnetic field induced undesirable magnetic field gradients. This work was followed up by Holz and Muller who suggested that the undesirable field gradients and their effects can be minimized if the electric... 

Schwartz, D. C., and C. R. Cantor, Separation of yeast chromosome-sized DNAs by pulsed field gradient gel electrophoresis. Cell 37 67-75, 1984. 

In electrophoresis an electric field is applied to a sample causing charged dispersed droplets, bubbles, or particles, and any attached material or liquid to move towards the oppositely charged electrode. Their electrophoretic velocity is measured at a location in the sample cell where the electric field gradient is known. This has to be done at carefully selected planes within the cell because the cell walls become charged as well, causing electro-osmotic flow of the bulk liquid inside the cell. From hydrodynamics it is found that there are planes in the cell where the net flow of bulk liquid is zero, the stationary levels, at which the true electrophoretic velocity of the particles can be measured. 

Electrophoresis The motion of colloidal species caused by an imposed electric field. The species move with an electrophoretic velocity that depends on their electric charge and the electric field gradient. The electrophoretic mobility is the electrophoretic velocity per unit electric field gradient and is used to characterize specific systems. 

Cells in aqueous suspension preferably are separated by physical methods under well-defined experimental conditions rather than by chemical modification that influences cellular viability or initiates cellular processes. Moderate physical forces and short separation time gready contribute to cellular integrity. In this chapter, the application of density gradient electrophoresis to the separation of mammalian cells is described. This process may be defined as the differential zonal movement of cellular particles of anionic character suspended in a stabilized liquid column under the influence of an external electrical field so that collection of differentially moved zones is feasible. 

DMF Dimethylformamide PFGGE Pulsed field gradient gel electrophoresis... 

Biological Applications of Pulsed Field Gradient Gel Electrophoresis... 

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