A shallow trench is formed to extend into a handle substrate of a semiconductor-on-insulator layer. Multiple respective senders are associated with multiple respective distributed portions of the media data. During operation, gas introduced through the tube mixes with the process fluid and the combined gas and fluid flow at a high rate with a high degree of turbulence along the first and second circulation paths defined around the weir, thereby promoting vigorous mixing and intimate contact between the gas and the process fluid. In apparatus embodying the invention, there is no need for a separate torch and for moving the torch during the shaping process. A pallet changer is arranged in the proximity of an end of the linear moving stage. Additionally, a self-adjusting overcurrent threshold circuit is provided.