This invention relates to the compounds represented by the general formula I, . Shadow data segments, whose contents are identical to an original data segment currently being written by a checkpoint operation, for users that require access for modification to data segments concurrently being written within a checkpoint operation. Affordable and simple manufacturing method is established with extrusion molding process or heat press molding process, after which extrusion cut process is conducted with the mold. A compressive liner layer deposited prior to the formation of the gap-filling silicon oxide layer is described and reduces the tendency for the subsequently deposited film to crack. A gel is disposed in the open cavity in contact with an exposed surface of the deflectable membrane. In the process, the precursor and the activator are mixed prior to introduction into the reactor in at least one mixing procedure, and then the mixture is contacted again with additional activator to essentially complete activation of the precursor.