Acknowledgments
This paper is dedicated to the memory of Professor J. W. Engels (University of Frankfurt, Germany), deceased in June, 2018. We would like to thank Professor A. Lachgar (Wake Forest University, Winston Salem, North Carolina, USA) for his help in making this work possible. The authors gratefully acknowledge the technical staff of the Centre of Analysis and Characterization, University Cadi Ayyad, Marrakech, for running analyses.