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Hydroxyapatite (IMA name: hydroxylapatite [5]) (Hap, HAp, or HA) is a naturally occurring mineral form of calcium apatite with the formula Ca 5 (PO 4) 3 (OH), often written Ca 10 (PO 4) 6 (OH) 2 to denote that the crystal unit cell comprises two entities. [6] It is the hydroxyl endmember of the complex apatite group.
When implanted, Bioglass 45S5 reacts with the surrounding physiological fluid, causing the formation of a hydroxyl carbonated apatite (HCA) layer at the material surface. The HCA layer has a similar composition to hydroxyapatite, the mineral phase of bone, a quality which allows for strong interaction and integration with bone. The process by ...
Apatite is the prototype of a class of chemically, stoichometrically or structurally similar minerals, biological materials, and synthetic chemicals. [53] Those most similar to apatite are also known as apatites, such as lead apatite ( pyromorphite ) and barium apatite ( alforsite ).
Apatite are also commonly found in biologic systems, where they are a frequent component of structures such as bone. Whitlockite is a rare phosphate mineral often represented as a type of apatite. However, it differs considerably from most other phosphate minerals, including apatite, in its chemical composition and the molar proportions of ...
The mechanical properties of the resulting porous scaffolds have been studied in various works of literature. [ 21 ] The printed 13-93 bioactive glass scaffold in the study by Liu et al. was dried in ambient air, fired to 600 °C under the O 2 atmosphere to remove the processing additives, and sintered in air for 1 hour at 700 °C.
Fluorapatite as a naturally occurring impurity in apatite generates hydrogen fluoride as a byproduct during the production of phosphoric acid, as apatite is digested by sulfuric acid. The hydrogen fluoride byproduct is now one of the industrial sources of hydrofluoric acid , which in turn is used as a starting reagent for synthesis of a range ...
Herderite is a phosphate mineral belonging to the apatite, phosphate group, with formula CaBe(PO 4)(F,OH). It forms monoclinic crystals, often twinned and variable in colour from colourless through yellow to green. It forms a series with the more common hydroxylherderite, which has more hydroxyl ion than fluoride. [2]
The tricopper site found in many laccases; note that each copper center is bound to the imidazole sidechains of histidines (color code: copper is brown, nitrogen is blue).. The active site consists of four copper centers, which adopt structures classified as type I, type II, and type III.