Abstract: An obstacle detection apparatus includes a rubber-like elastic body interspersed with electroconductive particles, and means for applying a voltage to the rubber-like elastic body to obtain an ultrasonic wave reception signal from a change in electrical resistance of the elastic body. An ultrasonic wave transmission apparatus is mounted on a support member for transmitting an ultrasonic wave outward. The rubber-like elastic body interspersed with electroconductive particles is provided along an outer periphery of the support member, and a voltage is applied to the rubber-like elastic body to obtain an ultrasonic wave reception signal from a change in electrical resistance of the elastic body as a result of receiving the ultrasonic wave reflected from an obstacle.

Abstract: Pigment dispersion is manufactured by continuously flushing pigment press-cake. First and second troughs supply hydrophobic liquid organic media and the pigment wet-cake respectively at a constant rate to a twin screw co-rotating extruder having a L/D (length/diameter) value of 25 or more. The twin screw co-rotating extruder includes a feeding part where the hydrophobic liquid organic media and the pigment wet-cake are fed from the first and second troughs, a flushing part for flushing the pigment particles from water phase to form an organic medium phase, and a dehydrating part for removing water from the flushed mixture. The hydrophobic liquid organic media and the pigment wet-cake are fed to the twin screw co-rotating extruder, and the pigment press-cake is flushed and dehydrated continuously in the extruder to obtain the pigment dispersion.

Abstract: A heavy metal ion adsorbent represented by the following general formula: ##STR1##wherein l, m, and n are 2 or 3, respectively; R is an alkyl group containing 4 to 6 carbon atoms which is substituted by an amino group in the .omega.-position; and A is hydrogen or a synthetic resin.