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Stoplogs of a hydro power plant which can close the water flow to the turbine. Stoplogs are hydraulic engineering control elements that are used in floodgates to adjust the water level or discharge in a river, canal, or reservoir. Stoplogs are sometimes confused with flashboards, as both elements are used in bulkhead or crest gates.
History of aluminium. Extrusion billets of aluminium in Yugoslavia, 1968. Aluminium (or aluminum) metal is very rare in native form, and the process to refine it from ores is complex, so for most of human history it was unknown. However, the compound alum has been known since the 5th century BCE and was used extensively by the ancients for dyeing.
Antihemorrhagic agents used in medicine have various mechanisms of action: Systemic drugs work by inhibiting fibrinolysis or promoting coagulation. Locally acting hemostatic agents work by causing vasoconstriction or promoting platelet aggregation.
Aluminium or aluminum ( 13 Al) has 22 known isotopes from 22 Al to 43 Al and 4 known isomers. Only 27 Al ( stable isotope) and 26 Al ( radioactive isotope, t 1/2 = 7.2 × 105 y) occur naturally, however 27 Al comprises nearly all natural aluminium. Other than 26 Al, all radioisotopes have half-lives under 7 minutes, most under a second. The standard atomic weight is 26.981 5385(7). 26 Al is ...
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Aluminium ( Aluminum in North American English) is a chemical element; it has symbol Al and atomic number 13. Aluminium has a density lower than that of other common metals, about one-third that of steel.
Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula AlCl3. It forms a hexahydrate with the formula [Al (H2O)6]Cl3, containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are colourless crystals, but samples are often contaminated with iron (III) chloride, giving them a yellow colour.