Abstract: An optical sensor comprises a plurality of light-sensitive members (10) each having an individually associated capacitor (11) which is charged with a current dependent upon the incident light sensed by the associated light-sensitive member (10); a light pulse source (12) providing light pulses from which the incident light is derived; and a control pulse source (14) providing pairs of consecutive pulses sandwiching the light pulses from the light pulse source (12), the first of which serves to discharge the capacitors (11) to a reference level prior to issue of a pulse by the light pulse source (12) and the second of which serves to effect read out from the capacitors (11) of the charge thereon deriving from the incident light from the preceding light pulse from the light pulse source (12), whereby the output of the sensor is not swamped by any stray charge on the capacitors (11).

Abstract: An optical analyzer and a developer recirculation system is used to determine the amount of photoresist polymer dissolved in a quantity of developer solution and the sensor output signal is utilized by a control computer to control the admission of fresh developer solution to replace used developer and maintain a fixed level of dissolved photoresist polymer to keep the developer bath at a fixed level of chemical activity.

Abstract: Paraffinic, olefinic and naphthenic hydrocarbons are converted to aromatic hydrocarbons by contacting the same at elevated temperatures with a catalyst comprising an alumina-supported composite of platinum, chlorine and a minor proportion of cesium, with or without other added metals such as iridium, rhodium, rhenium and the like.

Abstract: Isobutylene is catalytically converted to 1-chloro-2-trifluoromethyl-3,3,3-trifluoropropene [(CF.sub.3).sub.2 C .dbd. CHCl] in a chlorofluorination reaction zone by passing a mixture of anhydrous hydrogen fluoride, chlorine and the isobutylene over a chromium oxide or metal fluoride chlorofluorination catalyst. Alternatively, the isobutylene feed is first prechlorinated, and the mixture of prechlorination fed for conversion to the desired (CF.sub.3).sub.2 C .dbd. CHCl, to a downstream fluorination reactor charged with the chlorofluorination catalyst.

Abstract: The trimer to tetramer ratio of an alpha-olefin oligomer is varied over a significant range in a continuous, multi-stage alpha-olefin oligomerization process including a first stage tank reactor and a final tube reactor by controlling the amount of conversion taking place in each stage. The multi-stage process is used to prepare various poly(l-decene) oligomer mixtures having different oligomer proportions for use as synthetic lubricants.