Das Verhalten von Hydroxylapatit in Lösungen

Abstract

Erst in neuerer Zeit sind das Vorkommen des Hydroxylapatits Ca,,(PO,) 6(OH) und seine Bedeutung erkannt wordenl) . Seine Eigenschaften sind jedoch bisher kaum untersucht worden, obwohl der Hydroxylapatit den Hauptbestandteil natiirlicher Phosphorite sowie der anorganischen Knochen-substanz2) bildet. I m Hinblick auf diese Bedeutung ist in der vorliegenden Arbeit das V e r h a l t e n v o n H y d r o x y l a p a t i t gegeniiber r e i n e m Wasser sowie waI3rigen L o s u n g e n v o n z. B. A m i n o s a u r e n , Gelat i n e u n d a n d e r e n S t o f f e n untersucht worden.

The Nature of the Mineral Phase of Bone.

“…When precipitation occurs above pH 6.2 in the presence of a sufficiently high calcium: phosphorus ratio in solution, there is an precipitous fall in pH indicating very rapid hydrolysis and, on isolation, the solid has already been converted to a hydroxyapatite (84,125,204,372). The final product obtained is determined principally by the pH at which the initial precipitation begins and ends and by the relative proportions of calcium and phosphate present (91,125,161,174,183,184,192,206,254).…”

On the Thermodynamics of the Interaction between the Solutes in Dilute Ternary Solutions

“…Ternary solutions in which both solutes are electrolytes exhibit a more restricted sort of regular behavior. 14 An appropriate generalization would seem to be that the law of eq. 8 is valid if components 1 and 2 are solutes at low concentration in a multicompo- nent system in which long range interactions are not important in determining the activities of both of these components.…”

“…By expressing In mi as a function of m2b and µ d In ?raib = (d In TOib/3m2b)^, dw2b + (d In mib/dto)m2b dp, (14) we can obtain a relation between the slope of the graph and ki Often it will suffice to prove that the correction term in (15) is negligible compared to ki, and in such cases the ideal-dilute solution approximation (i.e., activity coefficients equal to unity) will be adequate for the estimation of the correction term from measured concentrations. In more difficult cases it would be appropriate to formulate the solute activity coefficients as in eq.…”