Anodal stimulation

As with most other metals, the anodic behaviour of nickel is influenced by the composition of the solution in which measurements are made, particularly if the solution is acidic. Acidic solutions containing d ions or certain sulphur compounds in particular have a pronounced influence both in increasing the rate of anodic dissolution in the active range and in preventing passivation, and in stimulating localised corrosion . Thiourea and some of its derivatives have a complex effect, acting either as anodic stimulators or inhibitors, depending on their concentration . 

A chain reaction is involved also in the anodically stimulated [2 + 2] cycloreversion... 

Thus anodal stimulation may result in an additional capture morphology on the BCG during the biventricular pacing threshold test. 

A modern phosphating bath often has a complex composition, but contains three essential components (i) free phosphoric acid (2) a primary metal phosphate and (3) an accelerator. The pH usually within the range 1.8 to 3.2 lower pHs are favoured for immersion deposits while spray processes often employ a high pH. The majority of routine phosphating processes involve open-circuit processing, but cathodic and (especially) anodic stimulation of the process is receiving increasing attention due to the possibilities of shorter process times and improved control over the deposited film. 

A deposit may be removed rapidly and selectively from the substrate by immersion in a suitable electrolyte, particularly in the reclamation of damaged or faulty electroplated workpieces. The technique may be carried out under open-circuit conditions or metal dissolution may be accelerated by anodic stimulation. The electrolyte may be chosen such that the substrate is immune or passive under the process conditions. In some circumstances, the rate of formation of this layer is enhanced by carrying out the coating electrochemically with the surfaces as the anode. Commonly, however, the layer is sprayed on and dried. 

Anodic/cathodic stimulation It has been demonstrated experimentally that in the case of electrical stimulation of peripheral nerves, cathodic stimulation has a lower threshold (less current required) than anodic stimulation. This experimental result can be directly explained by plotting Veq for a cathodic and anodic electrode (1 mA) located 1 cm away from an 10-/um unmyelinated fiber (Figure 28.7). The maximum value of Veq for anodic stimulation is 0.05 mV at the two sites indicated by the arrow. However, the maximum depolarization for the cathodic electrode is significantly larger at 0.2 mV with the site of excitation located directly underneath the electrode. In special cases, such as an electrode located on the surface of a cortex, cathodic stimulation can have a higher threshold [Ranck, 1975]. 

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