Tantalum radiography of the respiratory tract in dogs.
ALTHOUGH radiography of the respiratory tract was suggested by Chevalier Jackson in 1918 1 the full potential of this diagnostic aid has never been realized. The major drawbacks of the three radiopaque materials thus far employed in radiography of the airway 1-4 have been that:
XXXI. Further Data on the Displacement Method in Sinuses
The initial report of the method of displacement irrigation of the nasal sinuses, published in April, 1926, was a bare outline of the procedure and comprised a very limited number of case reports.' Since that time more cases have been studied and time has permitted a more complete observation of the results obtained. It is the purpose of this paper to consider these cases and the problems they involve, to outline the method in detail and to discuss the difficulties likely to be encountered. Under proper control and with certain precautions, our percentage of successes in introducing the fluids wherever desired has been high. Failures in injecting sinuses due to lapses in the method have practically disappeared. Failure of fluids to penetrate, due to pathologic changes about the ostia occur, and are considered of diagnostic importance.
The crystal structure of stilpnomelane. Part II. The full cell
Summary The structural formula of stilpnomelane averaged from 37 representative literature analyses and based on the determined structure is (Ca,Na,K)4(Ti0·1Al2·3Fe35·5Mn0·8Mg9·3)[Si63Al9](O,OH)216·nH2O. Ferrostilpnomelanes have up to 12 R 3+ cations in the octahedral sheet, ferristilpnomelanes commonly have between 24 and 30 R 3+ cations, rarely up to 37. The two groups can be distinguished by accurate X-ray powder diffraction, ferrostilpnomelanes having d 001 less and a greater than have ferristilpnomelanes. The unit cell is triclinic, a = b∼21·8 Å, γ = 120°, d 001∼12·2 Å, P . Hexagonal groups or ‘islands’ of 24 silicon-oxygen tetrahedra co-ordinate to the octahedral sheet, the centres of the ‘islands’ are displaced by 5a/12, 8b/12 on either side of the octahedral sheet as a result of warping of this sheet to permit articulation with the smaller tetrahedral sheet. The 24-tetrahedra ‘islands’ are linked laterally by 6-member rings of inverted tetrahedra, which in turn link at their apices to like rings connecting the next sheet of ‘islands’. Thus a single tetrahedral layer is 4 tetrahedra thick and has symmetry 6/m. The 6-member rings of tetrahedra act as hinges permitting up to 0·5 Å extension or contraction of the tetrahedral sheet to accommodate variations in the octahedral sheet dimensions with varying R 2+/R 3+ ratio.