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The first category, which he referred to as "major minerals", included well-known metals such as gold, silver, copper, tin, lead, and iron. The second category, labeled "minor minerals", encompassed substances like salts, atramenta (iron sulfate), alums, vitriol, arsenic, orpiment, sulfur, and similar substances that were not metallic bodies. [186]
In the early work on the chemical composition of the sun the only elements that were detected in spectra were hydrogen and various metals, [41]: 23–24 with the term metallic frequently used when describing them. [41]: Part 2 In contemporary usage all the extra elements beyond just hydrogen and helium are termed metallic.
A generalization is that minerals with metallic or adamantine lustre tend to have higher specific gravities than those having a non-metallic to dull lustre. For example, hematite , Fe 2 O 3 , has a specific gravity of 5.26 [ 89 ] while galena , PbS, has a specific gravity of 7.2–7.6, [ 90 ] which is a result of their high iron and lead ...
A-DNA is a form of DNA that occurs when the DNA is in a dehydrated state or is bound to certain proteins, and it has a shorter and wider helix than B-DNA. The helix of A-DNA is also tilted and compressed compared to B-DNA. A-DNA is believed to play a role in certain biological processes, such as DNA replication and gene expression.
Non-water solvents Hydrogen fluoride-based life Hydrogen fluoride has been considered as a possible solvent for life by scientists such as Peter Sneath. [citation needed] Hydrogen sulfide biochemistry Non-water solvents Hydrogen sulfide-based life Hydrogen sulfide is a chemical analog of water, but is less polar and a weaker inorganic solvent.
The A form occurs under non-physiological conditions in partly dehydrated samples of DNA, while in the cell it may be produced in hybrid pairings of DNA and RNA strands, and in enzyme-DNA complexes. [ 54 ] [ 55 ] Segments of DNA where the bases have been chemically modified by methylation may undergo a larger change in conformation and adopt ...
The term biometal can be used as a synonym to a metallic element that is involved in the function of a biomolecule, [16] hence also artificial systems can be considered when talking about biometals. Systems such as metalloproteins , metallopeptides and artificial metalloenzymes are examples of biomolecules containing metallic elements.
Non-toxic; in humans, it often substitutes for calcium. [11] sulfur: 16: 5: Sulfur is essential and ubiquitous, partly because it is part of the amino acids cysteine and methionine. Many metals that appear as enzyme cofactors are bound by cysteine, and methionine is essential for protein synthesis. Toxic in some forms. tantalum: 73: 1c