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Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is widely distributed in the Earth's crust. [10] Most of the world's commercial neodymium is mined in China, as is the case with many ...
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
In 1934, Willard Libby reported that he had found weak beta activity in pure neodymium, which was attributed to a half-life over 10 12 years. [25] Almost 20 years later, it was claimed that the element occurs in natural neodymium in equilibrium in quantities below 10 −20 grams of promethium per one gram of neodymium. [ 25 ]
Its discovery is generally believed to have originated in India around the 4th century AD, [65] although Singaporean mathematician Lam Lay Yong claims that the method is found in the Chinese text The Nine Chapters on the Mathematical Art, from the 1st century AD. [66] 60 AD: Heron's formula is discovered by Hero of Alexandria. [67]
For example, technetium-99m is a radioactive tracer that medical imaging equipment tracks in the human body. [ 21 ] [ 85 ] It is well suited to the role because it emits readily detectable 140 keV gamma rays , and its half-life is 6.01 hours (meaning that about 94% of it decays to technetium-99 in 24 hours). [ 28 ]
The oldest known iron objects used by humans are some beads of meteoric iron, made in Egypt in about 4000 BC. The discovery of smelting around 3000 BC led to the start of the Iron Age around 1200 BC [15] and the prominent use of iron for tools and weapons. [16] Recognised as an element by Guyton de Morveau, Lavoisier, Berthollet, and Fourcroy ...
The discovery of human bone fragments sent the researchers digging through the material excavated about nine decades ago — in which they found additional skeleton fragments.
Rare earths were mainly discovered as components of minerals. The term "rare" refers to these rarely found minerals and "earth" comes from an old name for oxides, the chemical form for these elements in the mineral. [16]: 5 A mineral discovered by Lieutenant Carl Axel Arrhenius in 1787 at a quarry in the village of Ytterby, Sweden.