ALEXANDRIA, Va., June 9 -- United States Patent no. 12,287,283, issued on April 29, was assigned to Ecolab USA Inc. (Saint Paul, Minn.).

"Linearized optical sensor calibration for measuring calcium" was invented by Hui Li (Bolingbrook, Ill.), Bingzhi Chen (Naperville, Ill.) and Brandon Davis (Oswego, Ill.).

According to the abstract* released by the U.S. Patent & Trademark Office: "An optical sensor may be used to measure the concentration of calcium in a water sample, such as a water sample obtained from industrial process water system like a cooling tower system, a boiler water system, or a waste water system. To measure the concentration of calcium, an indicator or reagent may be added to the water sample to form a complex that absorbs...