My heart is filled with gratitude to everyone who have accompanied me through my PhD journey. The completion of this research would not have been possible without the contribution of many individuals.First and foremost, I would like to extend my sincerest gratitude to my main supervisor, Prof.Gerhard Grüber. His valuable advice, encouragement, and insightful comments have provided a rewarding learning experience. I appreciate the life lessons, many of which will be carried with me throughout my whole life. I am extremely grateful to Prof. Roderick Wayland Bates. Prof. Bates first sparked my interest in research during my first year of my undergraduate studies. His patience, immense knowledge, and unwavering support have played a big role to where I am today.I would like to thank my mentor, Prof. Thomas Dick, and Prof. Kevin Pethe, for their valuable suggestions and advice. Special thanks to their students, Mr. Jickky Palmae Sarathy, Ms. Lee Bei Shi, and Ms. Ekaterina Sviriaeva, for the enjoyable moments where we exchanged ideas and experiences.