Electrode sharpening

In order to pilot this process, SNPE has developed an annular ceU having a cone-shaped electrode section. The magnesium anode is placed into the conic section and fed like a pencil into a sharpener as it is consumed during electrolysis. The carbon dioxide is introduced into the electrolyte externally to the cell. 

Fig. 15. Pencil sharpener electrolysis cell using consumable electrodes [115]...

Continuous systems use the same buffer, at constant pH, in the gel, sample, and electrode reservoirs. With continuous systems, the sample is loaded directly on the gel in which separation will occur. The sample application buffer is the same as the gel and electrode buffer, but at about half the concentration. The localized voltage drop that results from decreased conductivity in the sample solution helps drive sample proteins into the gel and sharpens protein bands. Once inside a gel, proteins are separated on the basis of their individual (gel-mediated) mobility differences. Bandwidths are highly dependent on the height of the applied sample... 

CDE is now filled with the indicator solution, the electrode is inserted in C, and the lower pinchcock at the top of F is adjusted so that the air column G is withdrawn sufficiently to permit a boundary to form between the indicator solution in CDE and the experimental solution in A. Even if the boundary is not initially sharp, it is soon sharpened by the current. 

In a different application, Williams and coworkers were interested in using the SECM to identify a precursor state to the pitting corrosion of stainless steel (12) and also to elucidate the mechanism by which a pit could be maintained and propagate further (13), once it had been initiated. For these studies, a commercial AFM (Quesant Resolver ) was adapted for use as an SECM. The tip electrode was a Pt-Ir wire electrolytically sharpened and insulated, as for electrochemical STM. A two-electrode mode was used with a Pt counterelectrode of much larger area than the stainless steel working electrode. The potential of the counterelectrode was standardized against an SCE. The probe UME was maintained at the same potential as the Pt counterelectrode. Typical tip-substrate separations of 0.1-0.5 /xm were employed for imaging purposes, with the distance carefully established by ap-... 

Figure 10.33 Capacitor discharge current flow through palmar skin. Monopolar electrode 1.3 mm diameter pin of steel, sharpened at the tip. Indifferent electrode on the underarm.

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