Abstract: Monomeric bisimides corresponding to the formula: ##STR1## wherein R is independently in each occurrence hydrogen, alkyl of from 1 to 20 carbons, aralkyl of from 1 to 20 carbons, halogen, or NO.sub.2 ; X' is F, Cl, OH, or NO.sub.2. These bisimides are useful in the production of various thermoplastic, polymeric materials such as polyetherimides, polyesterimides, and poly(carbonate imides).

Abstract: This invention relates to a method for simultaneously determining particle concentration and velocity in multi-phase streams. These determinations may be made by use of a fiber optic probe that establishes an illuminated sensing zone of finite dimensions. The probe collects light backscattered from the zone at discrete points in time. The collected light is converted to a voltage waveform. By taking the mean of the voltage values, concentration can be determined, and, by taking a derivative of the voltage waveform, the velocity can be determined.