Effects of Applied Electric Fields

As mentioned earlier in this chapter dislocations in ionic crystal may carry a net electric charge. Therefore, their motion may be influenced by applied electric fields, and may generate observable fields external to a specimen during plastic flow. These effects have been studied by Li (2000) and others. 

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The ionic conductivities of most solid crystalline salts and oxides are extremely low (an exception are the solid electrolytes, which are discussed in Section 8.4). The ions are rigidly held in the crystal lattices of these compounds and cannot move under the effect of applied electric fields. When melting, the ionic crystals break down, forming free ions the conductivities rise drastically and discontinuously, in some cases up to values of over 100 S/m (i.e., values higher than those of the most highly conducting electrolyte solutions). 

Moreover by measuring the effect of applied electric field on the ionic yield, it is possible to estimate the importance of ionic processes17. Results obtained for ammonia are shown in Table 5. 

It is interesting that the ratio of ionic to non-ionic decomposition is not significantly dependent on temperature. The effect of applied electric field on the y-radiolysis of hydrocarbon gases has also been investigated18. 

Imposed Field Effects. In this section we have set forth a set of equations to describe pattern formation in a multicellular electrophysiological system. A central goal of the theory is to study the effects of applied electric fields. This is done by imposing appropriate boundary conditions on the equations developed here. For example, assume we subject a one dimensional tissue to fixed ionic currents 1. Then if the tissue is in the interval 0 x along the x axis, the boundary conditions for the electro-diffusion model of the small gradient theory, i.e. (6k), are replaced by J = I at x = 0, L. One expects the richness of effects to include hyperpolarizability, induction of new phenomena and imperfect bifurcations to be found in these systems... 

Second, the effect of applied electric field changing the mixing of neutral and charge-separated forms of the charge-transfer chromophores will define the magnitude of electric field required to achieve a given phase shift. Molecular first hyperpolarizability (3 can be understood within the framework of the parameters of this two-state charge-transfer process, as shown in Eq. (5) (see also the Appendix) ... 

Coexistence Properties for the Polarizable Point Charge Model of Water and the Effects of Applied Electric Field. 

This technique was also used to monitor the effects of applied electric fields on hybridization and dchybridization not surprisingly, it was found that even small fields can significantly accelerate these processes. Mismatched sequences were particularly susceptible to potential-induced dehybridization, an effect that is potentially useful in discriminating between closely related sequences. As similar electric fields are involved in electrochemical assays, the effects of these fields on the DNA-film structure must be considered in the design and interpretation of DNA detection experiments. 

Optical examination of the effects of applied electric fields provides a sensitive technique for investigating the structure of nematic liquids. Two distinct kinds of interfaces exist in pure nematic liquids. One corresponds to the crystallite boundaries in ordinary polycrystalline solids. The other is the interface between domains which shows effects of interfacial tension in p-methoxycinnamic acid. In other nematic liquids this effect is not found. 

Ghai, RS, Bikson, M, Durand, DM (2000) Effects of applied electric fields on low-ctilcium epileptiform activity in the CAl region of rat hippocamptil slices. J Neurophysiol, 84 274-280. 

Gaussian DOS (electric field assumed to be negligible), (b) The effect of applied electric field (V/cm) on the density dependence of the mobility. 

Figure 43 Effect of applied electric field on the migration rates of Cu, Cu2S (80% Cu) and FeS droplets on the surface of synthetic fayalite slag (70% FeO) at 1523K...

Wang, H., and Singh, R.N., Crack propagation in piezoelectric ceramics Effects of applied electric fields, J. Appl. Phys., 1997, 81[1], 7471 7479... 

Gluckman BJ, Neel EJ, Netoff TI, Ditto WL, Spano ML, Schiff SJ (1996) Electric field suppression of epileptiform activity in hippocampal slices. J Neurophysiol 76(6) 4202-4205 Ghai RS, Bikson M, Durand DM (2000) Effects of applied electric fields on low-calcium epileptiform activity in the CAl region of rat hippocampal slices. J Neurophysiol 84(1) 274-280... 

EFFECTS OF APPLIED ELECTRIC FIELDS ON THE QUANTUM YIELDS OF INTERMEDIATES... 

As discussed in the introduction section, it is also possible to measure the effects of applied electric fields directly on the kinetics of primary charge separation. This is a difficult experiment with an isotropic sample [6], and although improved experiments are currently in progress, no new results are available yet. In lieu of such direct measurements, indirect information can be obtained from measurements of field effects on the quantum yield of intermediates. The results are discussed in detail elsewhere... 

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