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Whereas the beta form had been identified in 1845, [3] α-PbO 2 was first identified in 1946 and found as a naturally occurring mineral 1988. [4] The alpha form has orthorhombic symmetry, space group Pbcn (No. 60), Pearson symbol oP12, lattice constants a = 0.497 nm, b = 0.596 nm, c = 0.544 nm, Z = 4 (four formula units per unit cell). [4]
Scrutinyite / ˈ s k r uː t ɪ n i. aɪ t / is a rare oxide mineral and is the alpha crystalline form of lead dioxide (α-PbO 2), plattnerite being the other, beta form. The mineral was first reported in 1988 and its name reflects the scrutiny and efforts required to identify it from a very limited amount of available sample material.
Including the bones of the middle ear and the hyoid bone, the head contains 29 bones. Cranial bones (8) Occipital bone; Parietal bones (2) Frontal bone; Temporal bones (2) Sphenoid bone (sometimes counted as facial) Ethmoid bone (sometimes counted as facial) Facial bones (15) Nasal bones (2) Maxilla (upper jaw) (2] Lacrimal bone (2) Zygomatic ...
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
Bone marrow comprises approximately 5% of total body mass in healthy adult humans, such that a person weighing 73 kg (161 lbs) will have around 3.7 kg (8 lbs) of bone marrow. [ 5 ] Human marrow produces approximately 500 billion blood cells per day, which join the systemic circulation via permeable vasculature sinusoids within the medullary ...
At a site of active bone resorption, the osteoclast forms a specialized cell membrane, the "ruffled border", that opposes the surface of the bone tissue. This extensively folded or ruffled border facilitates bone removal by dramatically increasing the cell surface for secretion and uptake of the resorption compartment contents and is a ...
An osteocyte, an oblate shaped type of bone cell with dendritic processes, is the most commonly found cell in mature bone. It can live as long as the organism itself. [1] The adult human body has about 42 billion of them. [2] Osteocytes do not divide and have an average half life of 25 years.
Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O.It occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure.