Current induced changes

The relationship between swelling and release in an electrically responsive hydrogel is shown in Fig. 8.12. The mechanism of the current-induced change in volume of the gel is shown as an insert to the figure. 

Fig. 21.9. Current induced changes in metallic silver nanowires made by template synthesis.

FIGURE 6. Current-induced changes of membrane polarization of the 2 2 1 proteinoid-ledthin cell. 

The paramagnetic spinel CdCr204, when surrounding a superconducting wire shows a kind of electrothermal behavior changes in current induce changes in temperature. A current in the wire has a magnetic field around it and the chromite... 

The combination of electrochemistry and photochemistry is a fonn of dual-activation process. Evidence for a photochemical effect in addition to an electrochemical one is nonnally seen m the fonn of photocurrent, which is extra current that flows in the presence of light [, 89 and 90]. In photoelectrochemistry, light is absorbed into the electrode (typically a semiconductor) and this can induce changes in the electrode s conduction properties, thus altering its electrochemical activity. Alternatively, the light is absorbed in solution by electroactive molecules or their reduced/oxidized products inducing photochemical reactions or modifications of the electrode reaction. In the latter case electrochemical cells (RDE or chaimel-flow cells) are constmcted to allow irradiation of the electrode area with UV/VIS light to excite species involved in electrochemical processes and thus promote fiirther reactions. 

In the absence of free charge in the disk, the electric displacement will be independent of position, although it will vary with time D = [D(t),0,0]. The current induced in the external circuit is attributable to changes in electric displacement within the disk and is given by... 

Nonlinear properties of normal dielectrics can be studied in the elastic regime by the method of shock compression in much the same way nonlinear piezoelectric properties have been studied. In the earlier analysis it was shown that the shape of the current pulse delivered to a short circuit by a shock-compressed piezoelectric disk was influenced by strain-induced changes in permittivity. When a normal dielectric disk is biased by an electric field and is subjected to shock compression, a current pulse is also delivered into an external circuit. In the short-circuit approximation, the amplitude of this current pulse provides a direct measure of the shock-induced change in permittivity of the dielectric. 

Figure 9.26 shows the steady state effect of applied current I on the induced changes, ArH2(=rH2 -r 2) and Ar0(=ro-io )> in the rates of consumption of H2 and O respectively, where the superscript o always denotes open-circuit conditions. The dashed lines in Fig. 9.26 are constant Faradaic efficiency, A, lines. The maximum measured A values are near 40 at low current densities. This value is in excellent qualitative agreement with the following approximate expression which can predict the magnitude of A in NEMCA studies ... 

Extrapolation of this model calculation to the future climate warming suggests that an amplification of the current rate of increase in atmospheric CO2 content could result from climate-induced changes in ocean circulation rates. 

Heat detectors are activated by either melting a fusible material, changes in electrical current induced by heat loads on bi-metallic metals, destruction of the device itself by the heat, or by sensing a rate of ambient temperature rise. 

---