Synchrotron micro X-ray fluorescence (XRF) spectroscopy with two-dimensional element mapping, micro X-ray diffraction (XRD), electron spin resonance spectroscopy (ESR) and atomic force microscopy (AFM) were used to investigate the chemical and structural nature of the enamel of a tooth from Troodon, a small theropod dinosaur. These methods show that the crystallites in the Troodon tooth are submicron-sized carbonated calcium hydroxyapatite, which are semi-randomly oriented with a preferred orientation of (002) towards the surface of the tooth. Transition metal ions are distributed in the voids between crystallite clusters. Comparison of the ESR spectra indicates that the Troodon tooth had less exposure to UV than a fossilized crocodile tooth.

By use of a theory due to Gasser, Tavard, and others, the leading first-order corrections to the spherically averaged atomic Compton profiles (CP's) beyond the impulse approximation, for some inert closed-shell monatomic systems (He, Ne, Ar, and Kr), are obtained. This is accomplished by employing the Kohn-Sham technique of the density-functional theory, which leads to a self-consistent description, as opposed to the popular ''effective-hydrogenic-potential'' theories used in this context. The resulting corrections to the CP's thus obtained are seen to compare well with the earlier effective hydrogenic estimates. The orbital corrections are seen to conform to an empirical rule put forth ealier by Gasser and Tavard [Phys. Rev. A 27,117 (1983)].