Crystallinity , bone

Crystallinity Bone altered within years Pleistocene dentin may be altered enamel unaltered 2, 9,11, 14,19, 27, 30,31,34,35, 38,41,42,44... 

Tc radiolabelled diphosphonate is injected intravenously and is rapidly absorbed into the extracellular fluid. Although the exact mechanism of uptake of the radiopharmaceutical from the extracellular fluid into the bone is not completely understood, it is thought that both the osteoblastic activity and vascularity of the bone have roles. Following uptake the radiopharmaceutical is then adsorbed onto the surface of the inorganic crystalline bone matrix. A few hours post injection the blood level is approximately 3.5% of the injected dose and bone uptake is at 50% of the injected dose (Thrall and ZiESSMAN 2001 Haasbeek and Green 1994). 

Blood Calcium Ion Level. In normal adults, the blood Ca " level is estabhshed by an equiUbrium between blood Ca " and the more soluble intercrystalline calcium salts of the bone. Additionally, a subtle and intricate feedback mechanism responsive to the Ca " concentration of the blood that involves the less soluble crystalline hydroxyapatite comes into play. The thyroid and parathyroid glands, the fiver, kidney, and intestine also participate in Ca " control. The salient features of this mechanism are summarized in Figure 2 (29—31). 

These materials are essentially combustion improvers and tend to have fairly simple formulations (e.g., 3% copper chloride, 7% manganese chloride, 90% ammonium chloride). They are designed to change the crystalline structure within the clinker crystal lattice and raise the clinker eutectic point, thus minimizing the formation of noncombustible clinker, residual ash, and other deposits. Feed rates are approxiimately 0.5 to 2.0 lb per bone-dry ton. 

BONE CHAR A decolorizing and de-ashing filtration material made from dried cattle bones that have been crushed and retorted (at >550°C) to activate their alkaline calcium phosphate crystalline structure and carbonaceous residue. 

Similarly, a composite of hydroxyapatite and a network formed via cross-linking of chitosan and gelatin with glutaraldehyde was developed by Yin et al. [ 169]. A porous material, with similar organic-inorganic constituents to that of natural bone, was made by the sol-gel method. The presence of hydroxyapatite did not retard the formation of the chitosan-gelatin network. On the other hand, the polymer matrix had hardly any influence on the high crystallinity of hydroxyapatite. 

US patent 6,696,601, Hydrate forms of alendronate sodium, processes for manufacture thereof, and pharmaceutical compositions thereof [102], New hydrate forms of alendronate sodium, having a water content of about 1-12%, and processes for their manufacture, are disclosed. New crystalline forms of alendronate sodium, and processes for manufacturing these, are also disclosed. These new forms of alendronate sodium are suitable for incorporation into pharmaceutical compositions for combating bone resorption in bone diseases. 

Kokubo et al. [16,17] showed that the hydroxyapatite formation on the surfaces of bioactive materials in the living body can be reproduced even in an acellular protein-free simulated body fluid (SB F) with ion concentrations nearly equal to those of human blood plasma. This indicates that the hydroxyapatite layer is formed through chemical reaction of the bioactive glass with the surrounding body fluids. The formed layer consists of carbonated hydroxyapatite with small crystallites and low crystallinity, which is similar to bone hydroxyapatite. Hence the bioactivity of a material can be evaluated even in vitro by examining the hydroxyapatite formation on its surface in SBF. 

Bone is an extremely dense connective tissue that, in various shapes, constitutes the skeleton. Although it is one of the hardest structures in the body, bone maintains a degree of elasticity owing to its structure and composition. It possesses a hierarchical structure and, as most of the tissues, is nanostructured in fact, it is a nanoscaled composite of collagen (organic extracellular matrix) and hydroxycarbonate apatite, (HCA, bone mineral). This nanostructure is in intimate contact with the bone cells (several microns in size), which result (at the macroscopic level) in the bone tissue. Figure 12.2 shows the bone hierarchical ordering from the bone to the crystalline structure of HCA. 

Bondline readout, 7 122 Bond number (Bo), 15 687t Bond orientational order, of liquid crystalline materials, 15 85 Bonds, fullerene, 12 233-234 Bond strength, in thermal bonding, 17 510 Bone, 7 273t. See also Bones citric acid in, 6 632t Bone fractures, 3 725 treatment, 3 725... 

Figure 4.7 Measurement of crystallinity index from IR spectrum of bone apatite. Reprinted from Journal of Archaeological Science 17, Weiner, S. and Bar-Yosef, O., States of preservation of bones from prehistoric sites in the Near East a survey , pp. 187-96, copyright 1990, with permission from Elsevier.

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