High-resolution heat-capacity studies near the nematic-smectic- A transition

High-resolution ac calorimetry measurements on the nematic-smectic-A transition in liquid-crystal compounds, whose values of TNATNI range from 0.94 to 0.99, indicate a crossover point at a value of TNATNI equal to 0.96 between critical behavior where α⁺=α^- is less than or equal to zero to behavior characterized by α⁺=α^-=0.25.