In this research various of 2,5-disubstituted 1,3,4-oxadiazole (Schiff base, oxo-thiazolidine , and other compounds) were synthesized from 2,5-di(4,4?- amino-1,3,4-oxadiazole ) which use quently synthesized from mixture of 4-amino benzoic acid and hydrazine in the presence of polyphosphorus acid. The synthesized compounds were characterized by using some Spectral data (UV, FT-IR, and 1H-NMR).

The simulation of passively Q-switching is four non – linear first order differential equations. The optimization of passively Q-switching simulation was carried out using the constrained Rosenbrock technique. The maximization option in this technique was utilized to the fourth equation as an objective function; the parameters, γa, γc and β as were dealt with as decision variables. A FORTRAN program was written to determine the optimum values of the decision variables through the simulation of the four coupled equations, for ruby laser Q–switched by Dy +2: CaF2.For different Dy +2:CaF2 molecules number, the values of decision variables was predicted using our written program. The relaxation time of Dy +2: CaF2, used with ruby was

    There is nothing new in saying that Baghdad is the capital of world culture for eight centuries during the Islamic caliphate, it was the Arab book manuscript and copied books worldwide touring most of the capitals of the world

The deviation from the rules and standards of the Arabic language is considered a melody, so the criteria were quantitative and temporal and be  deviate from the general rule  which are called abnormal and accept in time in the age of eloquence.

أظهرت الدراسات الاعلامية واللغوية السابقة التي تناولت واقع اللغة العربية في شبكات التواصل الاجتماعي ثلاث مشكلات لغوية في هذا الميدان الأولى تمثلت بالثنائية اللغوية التي تجلت باستعمال عدد من مفردات اللغة الانكليزية الى جانب اللغة العربية ، والثانية تمثلت بالإزدواجية اللغوية التي تجلت في مزاحمة اللهجة المحلية للفصحى في النصوص المكتوبة ، والثالثة ارتبطت بمشكلة الضعف اللغوي في مستويات اللغة الكتابية والمع