Abstract: A device, system and method for the detection and screening of plastic microparticles in a sample is disclosed. A nanoporous silicon nitride membrane is used to entrap plastic microparticles contained in the sample. The sample may be a water sample, an air sample, or other liquid or gas sample. The entrapped plastic microparticles are then heated or otherwise processed on the nanoporous silicon nitride membrane. An imaging system observes the nanoporous silicon nitride membrane with the entrapped plastic microparticles to determine the type and quantity of the various plastic microparticles that are entrapped on the membrane.

Abstract: An intercommunication system in which a plurality of stations are interconnected by a single common line and each station is set to receive signals within a voltage "window" different from that of all the other stations of the system, and is operable to transmit signals at a voltage level selected in dependence on which of the stations is intended to receive the signals, in which all stations are further provided with a lock-out gate which disables them from transmitting when another station is already transmitting. The signal selection function and signal transfer function on the receiver part of each station are separated to permit equalization of the transmission voltage "window" for all biasing voltage levels.