Working on my dissertation and its completion are important hallmarks for me and my academic career. This dissertation was indeed very important for me and on its completion I would like to acknowledge and appreciate one and all that have helped me in this journey of knowledge. My first and foremost appreciation and thankfulness is towards Almighty who not only provided opportunities but also bestowed me with the capability and courage. Secondly, I would like to thank my parents, all of my teachers, library staff of my university, and my sincere thankfulness to my advisor Dr. Elango Rengasamy, who not only facilitated me but also guided me whenever I required their help and mentoring. Then, I am thankful to all of my family and friends who ...