Any Martirosyan (doctorand (UAB)), Judit Molera (IP of the experiment and co-director UVIC-UCC), Xavier Jornada (co director UAB), Assumpció Malgosa (co-director UAB), Miquel Colomer (UB), Carolina Sandoval (UAB), Helena Hernandez (UAB) and Núria Johnson (UAB) participated at ALBA experiment at XALOC beamline from 3.03.203 to 6.03.203 to to determine the neonatal line in primary teeth of the Iron Age Iberians.
Judith Juanhuix (ALBA staff) conducted the experiment on a beamline devoted to Crystallography. XALOC aims to provide the present and future Structural Biology groups with a flexible and reliable tool to help in finding solutions for structures of macromolecules and complexes. The beamline copes with a broad variety of crystal sizes and unit cell parameters, and allows both wavelength dependent and independent experiments.
Primary teeth start to form between the sixth and eighth week of prenatal development. An accentuated marking line, the neonatal line (NNL), forms at birth caused by the physiological
changes that alter the enamel and dentine matrix production. The NNL is the only method to distinguish from skeletal remains if a child died before or after birth and to calculate an infant’s
exact period of survival (chronological age) by measuring the amount of postnatal dental tissue formation. The study of the NNL in perinatal individuals from the Iberian archaeological site of Els Vilars (Arbeca) will allow us to determine if they were stillbirth or newborns as well as their chronological age and, therefore, establish the mortality pattern of these individuals (attrition vs violence) and to shed light on the controversy surrounding the practice of infanticide in Iberian culture.
To observe the NNL in teeth is necessary to prepare thin sections and observe them by optical microscopy. We expect to identify NNL in samples where is not possible to determine it by OM, due to the existence of different stress lines. With its non-destructive feature, superior special resolution, and relatively short acquisition time, -SRXRF is a reliable method to study of
microdistribution of Zn, Ca and Sr. The higher amount of Zn will allow us to identify and ensure the presence of the NNL and consequently differentiate it from other accentuated lines in enamel tissue. Moreover, we want to determine if NNL have a different crystallinity index (CI), because is still in the debate why is only visible in OM, and difficult to determine in SEM and other techniques.
XALOC beamline is requested instead of other micro-XRD or micro-XRF beamlines because of (a) the ability to perform X-ray microdiffraction simultaneously with microfluorescence, allows to determine the crystallinity index of c-HA at the same time as one measures the chemical composition (b) the ability to perform scans 1D crossing the NNL with a beam of 10 microns (c) the photon energy could reach 17 keV, (d) the large active area of the detector which allows characterising a wide variety of compounds with different crystallographic parameters, and (d) a suitable sample holder and scanning range.
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