||I have visited the University of Oklahoma OU in the United States for 2 months between March and April 2014. The aim of the trip was to perform tests in the laboratory of Professor Gerald Miller and also to exchange knowledge and experience and to get valuable feedback to improve my research topic. I had the chance to follow scientific lectures, and to join presentations and academic meetings which were very useful. From other hand, I had great time enjoying the atmosphere inside the campus joining the sport events, musical consorts, and the activities offered by the graduate college. I also visit Professor Jorge Zornberg at the University of Texas at Austin. I had a discussion with him about my research topic and visited his experimental laboratory and received valuable feedback and literature about my research topic. The whole experience in the United States was positive and helpful to my research and valuable personal experience as well. I am very grateful and appreciative for the help and support from the research school.