A novel orbital welder includes a body defining a tube passage, a weld tip, a rotor, a light source disposed to emit light toward the tube passage such that the emitted light will impinge upon one or more tubes placed in the tube passage, and a detector to detect the light emitted by the light source from the tube passage. An information processing apparatus handles strings. The topsheet has a liquid shut-off region in a line shape and adapted to prohibit migration of a liquid in the topsheet. These nanostructures may be synthesized \u201cmetal free\u201d. Fresh air enters through a bottom intake opening in the bottom intake and the lower portion of the intakeexhaust opening.