Couldn't generate code for the following reason:
Variable has units cell which are incompatible with the units first_order_rate_constant on a connected variable.; 
  In MathML apply element.
  In MathML math element.
  In CellMLComponent element with cmeta:id HC with name HC.
  In Model element with cmeta:id joseph_zavros_merchant_kirschner_2003_version01 with name joseph_zavros_merchant_kirschner_2003_version01.