Symbol (chemistry) the material was known in ancient times, while for others, the name is a more recent invention. For example, "He" is the symbol for helium (New Latin name, not known in ancient Roman times), "Pb" for lead ("plumbum" in Latin), and "Hg" for mercury ("hydrargyrum" in Greek). Some symbols come from other sources, like "W" for tungsten ("Wolfram" in German, not known in Roman times). Temporary symbols assigned to newly or not-yet synthesized elements use 3-letter symbols based on their atomic numbers. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of "unniloctium".
Selective laser melting Selective laser melting Selective laser melting (SLM), also known as direct metal laser sintering (DMLS) or laser powder bed fusion (LPBF), is a rapid prototyping, 3D printing, or additive manufacturing (AM) technique designed to use a high power-density laser to melt and fuse metallic powders together. In many SLM is considered to be a subcategory of selective laser sintering (SLS). The SLM process has the ability to fully melt the metal material into a solid three-dimensional part unlike SLS. Selective laser melting, one of the several 3D printing technologies, started in 1995 at the Fraunhofer Institute ILT in Aachen, Germany,