Nitrocellulose was found to gradually decompose, releasing nitric acid and further catalyzing the decomposition (eventually into a flammable powder). Decades later, storage at low temperatures was discovered as a means of delaying these reactions indefinitely. The great majority of films produced during the early 20th century are thought to have been lost either through this accelerating, self-catalyzed disintegration or through studio warehouse fires. Salvaging old films is a major problem for film archivists (see film preservation ).
Conventionally, potent to super potent steroids have been used for palmoplantar psoriasis for periods up to 6-8 weeks and sometimes even longer. Newer formulations being used now include BMV % foam (Luxiq; Connetics Corp., Palo Alto, CA, USA) and CP % foam (OLUX, Connetics Corp.). These foam formulations offer cosmetic advantages over traditional forms, including minimal residue after application, quick drying, ease of application and lack of fragrance. These advantages may lead to improved compliance and hence efficacy.  ,  ,