Ionic concentration profiles

Fig. 5.4.5. Steady ionic concentration profiles for e=io-4. —, cationic concentration, ----, anionic concentration.

Ionic concentration profiles (c - continuous line, c - dashed line) for e = 10 and four values of voltage 1-V = 0,... 

Fig. 4 Electric potential and ionic concentration profiles (marked with the respective subscripts 1, 2, 3) in a ternary system with z- = Z2 = 1, Z3 = —2, for a concentration ratio electroactive to inactive cation arid two values of the...

This shows that cations and anions have an equal contribution to the compensation for the surface charge. At the PZC, there is no charge and no countercharge, but if Co becomes slightly positive, for example, half the charge ao is compensated for by excess anions from the electrolyte (counterions attracted by the surface), and the other half is provided by a deficit in cations (co-ions repelled by the surface). The ionic concentration profile is shown in Figure 6.7. 

Typically, in vitro tests are cell- or tissue-based experiments. The aim is to study the biochemical functions of the target as a result of binding to potential drug ligands. Parameters such as ionic concentrations, enzyme activities, and protein expression profiles are studied. 

Fig. 3 -13. (a) A ion levels at the surface and in the interior of ionic compound AB, and (b) concentration profile of lattice defects in a surface space charge layer since the energy scales of occupied and vacant ion levels are opposite to each other, ion vacancies accumulate and interstitial ions deplete in the space charge layer giving excess A ions on the surface. 

The concentration profile of excess ions in the diffuse layer may be derived from Eqn. 5—3 and Boltzmann s distribution equation as a function of interfadal chai ge. Oh- Simple calculation gives the interfadal ionic concentration (at the OHP) to be c,.o = 1 M for an interfadal charge ay = 0.1 Cm" (corresponding to... 

Some typical stationary voltage-current VC curves along with the ionic concentration, space charge density, and the electric field intensity profiles for an intermediate voltage range are presented in Fig. 5.3.1. The appropriate profiles are constructed using a numerical solution of the system (5.3.1), (5.3.5). The essence of the numerical procedure employed for this and similar problems discussed in due course is as follows. 

The surface potential (j)s depends on the concentration profiles of all ionic species present at the interphase, including ionic strength affecting the diffuse layer, specifically adsorbed ions, and surface ionizable groups. Thus, the surface itself possesses acid-base properties that are reflected in the response of the immobilized indicator dye but are not uniquely linked to the pH of the bulk of the solution. 

Figure 50. Snapshots of oxygen incorporation experiments in Fe-doped SrTi03, recorded by in situ time and space resolved optical absorption spectroscopy.256 Rhs column refers to the corresponding oxygen concentration profiles, in a normalized representation. Top row refers a predominantly diffusion controlled case (single crystal), center row to a predominandy surface reaction controlled case (single crystal), bottom row to transport across depletion layers at a bicrystal interface.257,258 For more details on temperature, partial pressure, doping content, structure see Part I and Ref.257-259 Reprinted from J. Maier, Solid State Ionics, 135 (2000) 575-588. Copyright 2000 with permission from Elsevier.

With the initial condition c (t= 0,x) = c °, and the boundary conditions / n = 0 (for an electronic electrode), fam = 0 for an ionic electrode or, dc Idt =0 for a reversible electrode one obtains with the flux equations and the continuity equation the following as solution for the concentration profile ... 

When dealing with currents in ionic solutes, one must take into account the finite diffusion of ions within the electrolyte. As mentioned in Section 6.21, Fick s83 second law of diffusion states that the time-dependence of the concentration profile in a one-dimensional planar system Co(x,t) depends linearly on the derivative of the concentration gradient ... 

Figure 22. L.h.s. Four basic space charge situations involving ionic conductors (here silver ion conductor) a) contact with an isolator, b) contact with a second ion conductor, c) grain boundary, d) contact with afluid phase. R.h.s. Bending of energy levels and concentration profiles in space charge zones ( = 0 refers to the interfacial edge).

Figure 8. The concentration profiles for the various ionic species as obtained from MC simulations applying grids of different resolutions. The system is symmetric for the center plane of the membrane, so the results obtained for the left and right sides are averaged.

Since an increase in the surfactant concentration results in a higher fraction of substrate bound to the aggregate, an increase of the rate effects is expected, as seen in the above example, as [surfactant] increases and when [surfactant] >cac. Consequently, an enzymelike rate versus concentration profile is anticipated with a tendency of the curve to plateau when all the substrate is transferred into the aggregate. However, this is correct only in case (3) and in case (1) when the counterion of the added ionic surfactant is the reactive species (Figure 7, right). In case (1) when the reactive ion is not added as the counterion of the ionic surfactant (and is, consequently, kept constant in concentration) and in case (2), reaction profiles go through a maximum as the concentration of surfactant is increased (Figure 7, left). 

Figure 5.16. Changes (relative to rainfall composition) in the ionic concentrations of leachates at several positions in the Adirondack forest canopy/soil profile. These positions are below the forest canopy below the soil surface organic (litter) layer and below the soil profile. All of the changes are reported in units of micromoles per liter. (Adapted from A. V. Mollitor and D. J. Raynal. 1982. Acid precipitation and ionic movements in Adirondack forest soils. Soil Sci. Soc. Am.. 46 137-141.)...

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