An improved process for making a high purity, crystalline aromatic dicarboxylic acid product which includes at least one step for crystallizing the product and wherein the crystallized product is thereafter subjected to a drying step. The ceramic particles and the metal particles are subjected to heating under a non-oxidizing environment to a temperature greater than the melting point of the metal but below the melting point of the ceramic particles, so that the metal is molten to form a metal melt that surrounds and bonds the ceramic particles, and then pouring and casting are performed in a non-oxidizing environment. Packet processors analyze incoming packets and add a services tag containing services entries to any packets. The operator can adjust the semiconductor optical amplifiers to illuminate or disable individual terminals, as required, and can alter the intensity of light supplied to the terminals to maintain a satisfactory signal level, minimising need for engineer visits. The shaft is disposed between the step pedals and the rear wheel and is coupled to the rear wheel by a chain and a pair of sprockets.