Structures and methods for memory devices are provided which operate with lower control gate voltages than conventional floating gate transistors, and which do not increase the costs or complexity of the device fabrication process. The display layer includes a plurality of transmissive pixels to collectively project a unified image onto the backside of the screen layer. When displaying an authentication page that is used for user authentication, the authentication system displays buttons including the authentication button composed of the login image and dummy buttons composed of other images. The musical instrument can be a having a granite sound board that is solid granite or a laminate of granite and wood. The subject of the invention is also the bituminous product that can be obtained by the above process, and its uses.