Large crystals of titanium silicalite or intergrowths of intergrown smaller crystals, having a mean particle size greater than 2 \u03bcm, have been found catalytically effective at commercially reasonable rates for the epoxidation of olefins in the presence of hydrogen peroxide. The system has a plurality of access devices which may be coupled to each other over a network such as the Internet. A reference voltage error correction architecture and method eliminate the reference voltage error due to the sampling action in the ADC. A gate electrode is arranged through a gate insulating film on that region of the base layer, which is located between the drift layer and the source layer.