At the end of {HEAD ~ its operating time}, the component has, for example, a depletion of aluminium in a region near {TAIL ~ the surface} 
At the end of { HEAD ~ its operating time } , the component has , for example , a depletion of aluminium in a region near { TAIL ~ the surface }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL