Anatomical landmarks: Dimensions of the mastoid air cell system in the Mediterranean population. Our experience from the anatomy of 298 temporal bones.

The mastoid apophysis originates from a recent phylogenetic formation, associated with the standing attitude and it is currently considered as an evolution of the bone super-structures. The aim of the present study was to measure the diameters of the mastoid and the temporal bone in the Greek adult population. A total of 298 temporal bones from 149 cadavers (74 male, 75 female) were examined. The distances between six landmarks were measured by means of a pachymeter on both vertical and transverse axes of the mastoids and the temporal bone. The estimated mean values for each dimension were as follows: vertical diameter, 2.37 ± 0.42 cm; transverse diameter, 2.33 ± 0.51 cm; anterior margin, 2.12 ± 0.67 cm; posterior margin, 1.96 ± 0.55 cm; oblong diameter, 10.30 ± 0.60 cm; while the mean distance between the mastoid apex and mandibular fossa calva was 3.67 ± 0.35 cm. Gender differences were detected for the vertical (P < 0.001), the transverse diameter of the mastoid (P < 0.001), the anterior (P < 0.001) and the posterior margin of the mastoid (P < 0.001). In both genders, the vertical diameter of the mastoid was positively correlated with the transverse diameter, as well as with its anterior and posterior margins. In the present study, direct measurements of the mastoid and temporal bone in a Mediterranean population are reported. This description may facilitate a more accurate surgical approach to the temporal bone structures

The influence of hydrating agents on the hydration of industrial magnesium oxide

BACKGROUND: The influence of different hydrating agents on the pH of the hydrating solutions, rate of hydration of MgO to Mg(OH)2 and product surface area was studied as a function of temperature of hydration. Hydrating agents used were aqueous solutions of ammonium chloride, magnesium acetate, magnesium nitrate, nitric acid, acetic acid, magnesium chloride, sodium acetate and hydrochloric acid and distilled water as control. RESULTS: There was not a significant difference in the hydration behavior of the hydrating agents up to 50 °C, where less than 10 % of magnesium hydroxide was formed. The amount of hydroxide increased at temperatures above 60 °C. When compared to the hydration in water, all the hydrating agents with the exception of sodium acetate showed a significant increase in the degree of hydration. Sodium acetate formed the lowest amount of magnesium hydroxide, ranging between 1.2 and 12.2 % magnesium hydroxide. The largest percentage (56.7 %) magnesium hydroxide was formed from the hydration in magnesium acetate. CONCLUSION: It seems that MgO hydration is a dissolution-precipitation process controlled by the dissolution of MgO. The increased degree of hydration in magnesium acetate is possibly due to the presence of acetate and Mg2+ ions.http://www.blackwell-synergy.com