A light emitting device is disclosed. A switch which supports a first data link layer protocol can support differentiated services for a second data link layer protocol without performing routing in the second data link layer protocol. Thus, the data can be rewritten not on the track basis but on the fragment basis, which can reduce loss of tape capacity significantly. An external connection terminal is formed on the other surface of the substantially flat interconnection substrate so as to penetrate through the substantially flat interconnection substrate and be electrically connected to the interconnection pattern. The beta radiation detector assembly senses beta radiation from the blood in the above mentioned portion of the conduit. Specifically membranes having metallothionein proteins from the brine shrimp Artemia are disclosed for removing metals from liquid substrates.