sentences:  In general, the free energy of forming a nucleic acid duplex is
  
  formula_6,
  
  where formula_7 represents the free energy associated with one of the ten possible the nearest-neighbor nucleotide pairs, and formula_8 represents its count in the sequence.Each Δ"G"° term has enthalpic, Δ"H"°, and entropic, Δ"S"°, parameters, so the change in free energy is also given by
  
  formula_9.Values of Δ"H"° and Δ"S"° have been determined for the ten possible pairs of interactions.