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
Safety barrier Safety barrier A safety barrier is a component which prevents passage into a dangerous area, commonly used to mitigate risk. Safety barriers may be hard barriers physically restricting passage or soft barriers that control circuits based on the presence of foreign bodies. A safety barrier is a component which prevents passage into a dangerous area. It is commonly used to mitigate risk in the Hazard-Barrier-Target model, as studied in safety science. Work Safe Victoria (an Australian organization) defines a Safety Barrier as a device that: Hard barriers are fixed or removable guards which prevent entry. There include fences, traffic barriers,