An improved die stacking scheme is provided. Surprisingly, Pd and Au alloys of Pt have been discovered to be superior for oxidative dehydrogenation in microchannels. The wall of the air introduction chamber slopes downwardly toward the air inlet and defines a lowest portion within the air introduction chamber. Electrical contact between the carrier substrate and semiconductor element is achieved with conductive connectors formed on either the semiconductor element or the carrier substrate. Retransmitted packets may be discarded.