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Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life. [ 3 ] [ 63 ] Selenium acts as the catalytic center of several antioxidant enzymes, such as glutathione peroxidase , [ 11 ] and plays a wide variety of other biological roles .
The name is mostly applied informally to compositions between 20–80% gold and 80–20% silver, but these are strictly called gold or silver depending on the dominant element. Analysis of the composition of electrum in ancient Greek coinage dating from about 600 BC shows that the gold content was about 55.5% in the coinage issued by Phocaea.
Gold, a chemical element; Genomes OnLine Database; Global-scale Observations of the Limb and Disk, a NASA Explorer Mission of Opportunity; GOLD (parser), an open-source parser-generator of BNF-based grammars; Graduates of the Last Decade, an Institute of Electrical and Electronics Engineers program to garner more university level student members
On the other hand, Ni–Ti–Cu wires are used for artificial heart muscles [22] and iron and gold particles can guide magnetic drug delivery or destroy tumor cells. [22] Bigger biometal structures (relying on metallic elements and alloys) in medicine can be classified into three types: fibre, bulk scaffolds, and nanotubes. [23]
Human uses of animals include both practical uses, such as the production of food and clothing, and symbolic uses, such as in art, literature, mythology, and religion. All of these are elements of culture, broadly understood. Animals used in these ways include fish, crustaceans, insects, molluscs, mammals and birds.
Gold compounds are compounds by the element gold (Au). Although gold is the most noble of the noble metals , [ 1 ] [ 2 ] it still forms many diverse compounds. The oxidation state of gold in its compounds ranges from −1 to +5, but Au(I) and Au(III) dominate its chemistry.
The use of gold compounds has decreased since the 1980s because of numerous side effects and monitoring requirements, limited efficacy, and very slow onset of action. Most chemical compounds of gold, including some of the drugs discussed below, are not salts, but are examples of metal thiolate complexes.
The Romans used a diverse range of materials for their jewellery from their extensive resources across the continent. Although they used gold, they sometimes used bronze or bone, and in earlier times, glass beads and pearl. As early as 2,000 years ago, they imported Sri Lankan sapphires and Indian diamonds and used emeralds and amber in their ...