Period 6 element devices though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light. Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray other metal resembles tin but discolors when exposed to air. The
System safety correcting risk perceptions by creating, analysing and understanding information model to show what factors create and control the hazardous process. For almost any system, product, or service, the most effective means of limiting product liability and accident risks is to implement an organized system safety function, beginning in the conceptual design phase and continuing through to its development, fabrication, testing, production, use and ultimate disposal. The aim of the system safety concept is to gain assurance that a system and associated functionality behaves safely and is safe to operate. This assurance is necessary. Technological advances in the past have produced