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