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Ions, electromigration

Figure 9. The electric fields and directions of positive ion electromigration in the near-surface region of both n- and p-type semiconductors under anodic and cathodic... Figure 9. The electric fields and directions of positive ion electromigration in the near-surface region of both n- and p-type semiconductors under anodic and cathodic...
The water transport number (tw) accounts for water transport associated to ion electromigration and thus controls the maximum solute weight concentration theoretically achievable in the concentrate. By dividing the instantaneous solute mass transferred into the C compartment by the actual volume accumulated into tank C for 6 tending to infinite, the following can be obtained ... [Pg.300]

Liquid Solid S/L Wetting, spreading, lubrication, friction, surface tension, capillarity, electrochemistry, galvanic effects, corrosion, adsorption, nucleation and growth, ion electromigration, optical properties, cleaning techniques. [Pg.332]

Electrically assisted transdermal dmg deflvery, ie, electrotransport or iontophoresis, involves the three key transport processes of passive diffusion, electromigration, and electro osmosis. In passive diffusion, which plays a relatively small role in the transport of ionic compounds, the permeation rate of a compound is deterrnined by its diffusion coefficient and the concentration gradient. Electromigration is the transport of electrically charged ions in an electrical field, that is, the movement of anions and cations toward the anode and cathode, respectively. Electro osmosis is the volume flow of solvent through an electrically charged membrane or tissue in the presence of an appHed electrical field. As the solvent moves, it carries dissolved solutes. [Pg.145]

Electromigration of Ions movement of ions under an electric field. [Pg.1367]

The addition of a spillover proton to an adsorbed alkene to yield a secondary carbonium ion followed by abstraction of a proton from the C3 carbon would yield both isomers of 2-butene. The estimated faradaic efficiencies show that each electromigrated proton causes up to 28 molecules of butene to undergo isomerization. This catalytic step is for intermediate potentials much faster than the consumption of the proton by the electrochemical reduction of butene to butane. However, the reduction of butene to butane becomes significant at lower potentials, i.e., less than 0.1V, with a concomitant inhibition of the isomerization process, as manifest in Fig. 9.31 by the appearance of the maxima of the cis- and tram-butene formation rates. [Pg.467]

There is difficulty in defining the absolute mobilities of the constituent ions in a molten salt, since it does not contain fixed particles that could serve as a coordinate reference. Experimental means for measuring external transport numbers or external mobilities are scarce, although the zone electromigration method (layer method) and the improved Hittorf method may be used. In addition, external mobilities in molten salts cannot be easily calculated, even from molecular dynamics simulation. [Pg.125]

The internal transport numbers may be measured most accurately and precisely by the Klemm method, which was developed for the purpose of isotope separation. This method has the following merits (1) It is insensitive to a small amount of impurities, such as water. (2) Even in the region of very small concentration of an ion of interest, 12 can be measured accurately. (3) It can be applied to additive ternary systems. An apparatus for the Klemm method of measuring 12 in nitrate mixtures is shown in Fig. I. This cell developed for nitrates by Okada s group has the following advantages compared with other electromigration cells ... [Pg.126]

Figure 7. Schematic representation ofprocesses of electromigration / diffusion of ions and formation of insulation passive layer on the boundary current collector / conductive polymer. Figure 7. Schematic representation ofprocesses of electromigration / diffusion of ions and formation of insulation passive layer on the boundary current collector / conductive polymer.
In paper or gel electrophoresis, the sample may be applied with a syringe or a micropipette similar to the application of samples to thin-layer plates. In some cases, there may be wells in the gel that accept the solution containing the species to be separated. In CE, samples may be applied using electromigration, hydrostatic, or pneumatic injection. In all cases, the ions to be separated must be soluble in and compatible with the stationary phases and buffers used. [Pg.284]

The pH value also affects the ionization of acidic and basic analytes and their electromigration. Since this migration can be opposite to that of the electroos-motic flow, it may both improve and impair the separation. This effect is particularly important in the separation of peptides and proteins that bear a number of ionizable functionalities. Hjerten and Ericson used monolithic columns with two different levels of sulfonic acid functionalities to control the proportion of EOF and electromigration. Under each specific set of conditions, the injection and detection points had to be adjusted to achieve and monitor the separation [117]. Another option consists of total suppression of the ionization. For example, an excellent separation of acidic drugs has been achieved in the ion-suppressed mode at a pH value of 1.5 [150]. [Pg.42]

New concepts presented in this edition include monolithic columns, bonded stationary phases, micro-HPLC, two-dimensional comprehensive liquid chromatography, gradient elution mode, and capillary electromigration techniques. The book also discusses LC-MS interfaces, nonlinear chromatography, displacement chromatography of peptides and proteins, field-flow fractionation, retention models for ions, and polymer HPLC. [Pg.696]


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See also in sourсe #XX -- [ Pg.88 , Pg.89 , Pg.90 , Pg.91 , Pg.92 , Pg.93 , Pg.94 , Pg.95 , Pg.96 , Pg.97 , Pg.98 , Pg.99 ]




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