The cartilaginous intra-articular disc of the human temporomandibular joint shows clear anteroposterior variations in its morphology. However, anteroposterior variations in its tissue behavior have not been investigated thoroughly. To test the hypothesis that the mechanical properties of fresh human temporomandibular joint discs vary in anteroposterior direction, we performed dynamic indentation tests at three anteroposteriorly different locations. The disc showed strong viscoelastic behavior dependent on the amplitude and frequency of the indentation, the location, and time. The resistance against deformations and the shock absorbing capabilities were larger in the intermediate zone than in regions located more anteriorly and posteriorly. Because several studies have predicted that the intermediate zone is the predominantly loaded region of the disc, it can be concluded that the topological variations in its tissue behavior enable the disc to combine the functions of load distribution and shock absorption effectively.

A uranyl peroxide, Na 5 [(UO 2) 3 (O 2) 4 (OH) 3 ](H 2 O) 13 , with an open sheet of uranyl polyhedra has been synthesized under ambient conditions and structurally characterized. The structure (orthorombic, Cmca, a) 23.632(1) Å, b) 15.886(1) Å, c) 13.952(1) Å, V) 5237.7 Å 3 , and Z) 8) consists of sheets composed of two symmetrically unique uranyl (UO 2) 2+ ions that are coordinated equatorially by two peroxide groups and two OHgroups, forming distorted uranyl hexagonal bipyramids of composition (UO 2)(O 2) 2-(OH) 2 4-. The uranyl bipyramids are connected into sheets with openings with dimensions 13.7 Å along [010] and 15.9 Å along [100]. The shortest dimension of the cavity is 8.08 Å. Sheets of two-dimensionally polymerized uranyl polyhedra are the most common structural type of inorganic uranyl phases; however, such an open topology has never been observed.

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