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