A multilevel power conversion circuit using a flying capacitor can include two bidirectional switches connected in series between a middle potential terminal of DC power supplies and a conversion circuit using semiconductor switches. A riser may include a frame that has therein a plurality of pivot pins. In some embodiments, the treatment fluid may be introduced into a portion of the subterranean formation at or above a pressure sufficient to create or enhance one or more fractures in the portion of the subterranean formation. Light may enter the thumbtack from either direction. This permits carbonyl chemistries to be used at ambient temperature, without heating.