Effect of surfactant alkyl chain length on lyotropic uniaxial to biaxial cholesteric phase transitions Erol Akpinar, Nazli Uygur, Seda Uyanik and Antônio Martins Figueiredo Neto Eur. Phys. J. E, 42 9 (2019) 128 Published online: 25 September 2019 DOI: 10.1140/epje/i2019-11893-8