**Notes/thanks/other declarations**

This work is dedicated to my honorable Ph.D. supervisor, Prof. Dr. Keying Shi, my colleague, my Lab fellows for their support and their unconditional help and valuable discussions, my students, my family members, loving father, great mother, sweet uncles, my brothers who were all a source of strength and inspiration for me. May Almighty Allah bless those long lives, happiness and prosperity!

And above all, I am eternally grateful to Almighty Allah who blessed me with the strength to write this unit.
