Period 6 element heavy metal, lead is a neurotoxin that accumulates both in soft tissues and the bones. Lead poisoning has been documented from ancient Rome, ancient Greece, and ancient China. Bismuth is a chemical element with symbol Bi and atomic number 83. Bismuth, a trivalent other metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally uncombined, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when newly made, but often seen in air with a pink tinge owing to the surface
Asymmetric C-element into account the common and the asymmetric minus inputs. All these inputs must be low for the down transition to happen. The figure shows the gate-level and transistor-level implementations and symbol of the asymmetric C-element. In the figure the plus inputs are marked with a 'P', the minus inputs are marked with an 'm' and the common inputs are marked with a 'C'. In addition, it is possible to extend the asymmetric input convention to inverted C-elements, where a plus (minus) on an input port means that an input is required for the inverted output to fall (rise). Asymmetric C-element