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
Sarah Liao annual air monitoring project. This program was designed to provide extensive background environmental data, which continued for five years. She then spent over seven years establishing and administering the program on Environmental Health & Safety at the University. Another area of work was the management of toxic and hazardous materials (chemical and biological) used in the University, including the procurement, storage, delivery, use, pre-disposal treatment and final disposal of these substances. At the same time she conducted large scale studies relating to workplace health and safety, hazard identification, risk assessment and environmental problems in a range of Hong Kong industries.