An image forming apparatus which uses toner to form an image on a sheet may cause the sheet to experience curl after passing through a fixing device which uses heat and pressure to fix the toner image on the sheet. A library of materials is provided. SiO2 is formed at an interface between the nozzle plate and the heater thin film due to heating and application of an electric field, and thus the nozzle plate and the heater substrate are bonded with an electrostatic force of SiO2. In embodiments intended for mitral valve repair, the eyelets are particularly adapted to receive sutures to secure the annuloplasty band to the antero-lateral trigone and postero-medial trigone. The rolled article is sintered to obtain a BSCCO 2223 oxide superconductor. In this ink-jet recording head, there are two-dimensionally arranged units, in each of which an ink pressure chamber, a partition wall serving as a driving portion, a pressure buffer chamber and a fixed wall are arranged in the same direction.