Doctoral dissertation Discussion of Researcher/ Muhammad Atef Muhammad Zahren was discussed in 31-5-2016. The discussion committee included; Prof.Dr. Hussein Ahmed Hesmat, prof. Dr. Muhmmad Sayed salama, Prof. Dr. Hussien Dory Abaza, Prof.Dr. Osama Salah Fouad, Prof.Dr. Muhmmad Isamil saad, Prof.Dr. Hamdy Muhammad Ali.