A channel system is disclosed for optimising the relation between pressure drop and heat, moisture andor mass transfer of fluids flowing through the system. The apparatus is a spare tire assembly configured to interface with a vehicle hitch. This invention also provides a pharmaceutical composition made by combining a therapeutically effective amount of a compound of the invention and a pharmaceutically acceptable carrier. In addition, the intermediate voltage generating portion generates a plurality of conversion voltages. The amines are also of use in combatting activation of the kininkallikrein system or blood coagulation system.