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T O Mason

Publications and source records attributed to T O Mason.

3 recordsLinked to original sources
PubMed2000

Cation disorder in Ga1212.

Substitution of calcium for strontium in LnSr2-xCaxCu2GaO7 (Ln = La, Pr, Nd, Gd, Ho, Er, Tm, and Yb) materials at ambient pressure and 975 degrees C results in complete substitution of calcium for strontium in the lanthanum and praseodymium systems and partial substitution in the other lanthanide systems. The calcium saturation level depends on the size of the Ln cation, and in all cases, a decrease in the lattice parameters with calcium concentration was observed until a common, lower bound, average A-cation size is reached. Site occupancies from X-ray and neutron diffraction experiments for LnSr2-xCaxCu2GaO7 (x = 0 and x = 2) confirm that the A-cations distribute between the two blocking-layer sites and the active-layer site based on size. A quantitative link between cation distribution and relative site-specific cation enthalpy for calcium, strontium, and lanthanum within the gallate structure is derived. The cation distribution in other similar materials can potentially be modeled.

Journal Article↗
PubMedDate not supplied

Gas bubbles in polymethylmethacrylate cranioplasty simulating abscesses: CT appearance.

Polymethylmethacrylate (PMMA) cranioplasty procedures were performed on 20 patients over a 2-year period. Nine of these patients had a total of 17 CT examinations, performed when clinically indicated. On 16 of the 17 CT scans, the appearance of the cranioplasty plate was characteristic of plates with gas bubbles. The appearance of these bubbles was stable over an extended period of time, ruling out clinical reasons for this appearance. The original interpretations of the CT scans were variable, inconclusive, or even erroneous. An understanding of the application of PMMA plates and their characteristics is necessary to accurately interpret the CT appearance of the PMMA cranioplasty plate.

Abscess↗