The resultsshow that the partialreplacement of TOBB by PBA decreased the phasetransitiontemperatures and narrowed the temperaturerange of mesophase formation.
But the project's current phase also includes replacement of five two-track bridges, which required reducing the number of active tracks from four to two.
The Air Force is also in the AoA phase in its search for a replacement for the T-38, which was the world's first supersonic trainer when it entered service in 1961.