A front-end assembly including a deflector and a catcher bracket. Apparatus, system and method may also include an insert, the insert encompassing the sides of the annealing chamber, and a cartridge case that is unevenly heated such that the cartridge case obtains at least a first hardness at a first location and a second hardness at a second location, the first hardness different from the second hardness. The resulting quantum dot-polymer nanocomposite is placed in a solution having a known pH and addition of a chemical composition or biological agent of interest generates a change in pH of that solution. By means of this invention, current pulses having freely variable amplitudes can be generated for the positive and negative current pulses by providing for each bridge circuit at least two d. The insulating block has first and second side surfaces which are facing the first and second inner side surfaces of the slit, respectively, and deformed to define first and second spaces between the insulating block and the first and second inner side surfaces of the slit. The invention also relates to articles produced from a nanocomposite and a process for preparing a nanocomposite.