The delta structures 200 have {HEAD ~ a lattice} 210 of interconnected strands which intersect to define {TAIL ~ a plurality} of cells 220 
The delta structures 200 have { HEAD ~ a lattice } 210 of interconnected strands which intersect to define { TAIL ~ a plurality } of cells 220
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH