The middle pair of seats had lower cushions that folded into
depressions in the floor, and the seat backs could be folded flat on top of them.
The researchers discovered that certain mixes of two configurations--a zigzag fold, called a crimp, and a doubled-back fold, or hero--permit a creased segment to be folded into
a flat profile.
The researchers found that the chains folded into
spiral structures resembling alpha helices in proteins, suggesting that hydrogen bonds are not central to the folding of alpha helices.
They then screened the different combinations for ones that folded into
the proper configuration.
This finding applied equally to freshly crumpled sheets, to previously crumpled sheets that were crumpled again, and to sheets that had been initially folded into
a regular, gridlike pattern of creases and smoothed out before crumpling.