  Coronal loop observations have existed for many decades yet the precise shape
of these fundamental coronal structures is still widely debated since the
discovery that they appear to undergo negligible expansion between their
footpoints and apex. In this work a selection of eight EUV loops and their
twenty-two sub-element strands are studied from the second successful flight of
NASA's High resolution Coronal Imager (Hi-C 2.1). Four of the loops correspond
to open fan structures with the other four considered to be magnetically closed
loops. Width analysis is performed on the loops and their sub-resolution
strands using our method of fitting multiple Gaussian profiles to
cross-sectional intensity slices. It is found that whilst the magnetically
closed loops and their sub-element strands do not expand along their observable
length, open fan structures may expand an additional 150% of their initial
width. Following recent work, the Pearson correlation coefficient between peak
intensity and loop/strand width are found to be predominantly positively
correlated for the loops (~88%) and their sub-element strands (~80%). These
results align with the hypothesis of Klimchuk & DeForest that loops and - for
the first time - their sub-element strands have approximately circular
cross-sectional profiles.
