Abstract: A device for detecting a transmissivity of a substance utilizing a transmitted light value, which comprises a light emitting element and a photo detecting element. The light emitting element and the photo detecting element are spaced from each other at a predetermined distance so that a transmitted light value of a substance passing through the space is detected as an amount of light transmitted therethrough. The photo detecting element further comprises a photo oscillator circuit including the photo detecting element as one component thereof and outputs a signal having characteristics selected from a cycle and a frequency corresponding to the transmitted light value, and when the condition of a substance exceeds a predetermined reference level, such information is displayed at a display unit.

Abstract: A carbon-based adsorbent comprising active carbon provided with electron-donative surface functional groups which are bonded directly and chemically to graphite constructing the surface of the active carbon and are coordinated with metallic ions to form chelate structures, which has adsorbing power similar to that of common active carbon and additionally the ability to remove specific harmful gas molecules and smelling gas molecules from air, thus being especially effective for gas filters.