A pitch adjustable bi-directional shovel includes a substantially flat blade including a forward edge and a rearward edge. The process for preparing the carbon quantum dots according to the present invention makes a mass production possible and the process thereof is simple. The sector selector includes a fixed address cell storage box for storing addresses of the defective bit lines and a flexible address cell storage box for storing addresses of the defective global bit lines. The frame is rotatably mounted such that the supports clean the layer of contaminant byproducts off of the surface of the ionizing wire when the frame is rotated, by physical andor by electrical means. In the process, a compound represented by the formula: 2Si5N8, silicon nitride and aluminum nitride are mixed and then fired in a nitrogen atmosphere under high pressure. In a preferred embodiment an impacted strut regains structural integrity after impact displacement and fracture by re-bonding.