13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- 3.2. SEM and EDS analysis In Fig. 6, a comparison between a normal chord (a), a moderately calcified one (b) -both previously tested up to fracture- and one MCT obtained from one of the strongly calcified MVs available for the research (c), are shown. Fig. 6. Comparison through SEM between: (a) a normal, (b) a moderately calcified and (c) a strongly calcified MCT. (d) General perspective of some surface calcium deposits; (e) detail of a deposit deeply rooted in the chord. 3.3. Determination of the calcium content present in the chordae through atomic absorption spectroscopy The calcium content of several MCT was determined through AAS. Specifically, the material analysed consisted of: (i) 15 MCT obtained from the 6 normal MVs, (ii) 8 MCT obtained from the 4 moderately calcified MVs and, (iii) 6 MCT obtained from the 3 strongly calcified MVs. The normal and moderately calcified chords were among those previously subjected to tensile tests (the two halves of each specimen were jointly analysed). The calcium content measured (expressed in terms of mg Ca / mg dry tissue) is represented in Fig. 7 (notice that a logarithm scale was used).
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