The soft emission of electrons from the beta emitting gas can not penetrate {HEAD ~ the glass wall} of {TAIL ~ the microspheres}, thereby constituting no radiation hazard 
of
The soft emission of electrons from the beta emitting gas can not penetrate { HEAD ~ the glass wall } of { TAIL ~ the microspheres } , thereby constituting no radiation hazard
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH