Do the short helices exist in the nematic TB phase?
  Dimeric compounds forming twist-bend nematic, Ntb, phase show unusual optical texture related to the formation of arrays of focal conic defects. Some of the focal conics show submicron internal structure with 8 nm periodicity, which is very close to that found in the crystalline phase of the material, suggesting surface freezing. 
Ewa Gorecka, Miroslaw Salamonczyk, Anna Zep, Damian Pociecha, Chris   Welch, Ziauddin Ahmed, Georg H. Mehl
cond-mat.soft