The number of metallic probes can be controlled to thereby control {TAIL ~ the amount} of {HEAD ~ metallic ions} produced 
The number of metallic probes can be controlled to thereby control { TAIL ~ the amount } of { HEAD ~ metallic ions } produced
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH