Double-sided etching techniques are disclosed for providing a semiconductor structure with one or more through-holes. Each bogie includes a chassis, two front wheels and two rear wheels. The disc brake pad adjustment mechanism has a caliper housing portion, an adjusting axle, an adjusting plate and an adjustment biasing member. The glass coating film is formed on at least part of a surface of the sensor element and capable of absorbing a Mn component contained in the exhaust gas at 700\xb0 C. Consequently, increased luminance is obtained. The base receptacle forms a seat for the front and back portions.