The first metallic electrode comprises copper or {HEAD ~ an alloy} of {TAIL ~ nickel} and copper 
of
The first metallic electrode comprises copper or { HEAD ~ an alloy } of { TAIL ~ nickel } and copper
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH