was being maintained

The zearalenone was added to the saturated acetic anhydride while it was being maintained at about 0.degree. to about -5.degree.C. with a dry ice-acetone bath.
US Pat. 3954805 - Commercial Solvents Corporation

Therein, by means of special equipment, an aqueous phosphatizing solution was sprayed onto a metal article, while the article was being maintained in a vapor degreasing zone.
US Pat. 4070521 - Diamond Shamrock Corporation

In Example II, a core was prepared in a manner similar to Example I and saturated with nitrogen at 2170 kilopascals. While the heater was being maintained at 232.degree.-245.degree. C. superheated pentane at 232.degree. C. was injected.
US Pat. 4450913 - Texaco Inc.