: Dependence of concentration of CO2, H2O2, pH- indicator and IR-spectra of ?- irradiated transformer oil, containing polychlorinebiphenyl (PCB) admixtures from adsorbed doses in the range of 4-136 kGy was studied. It was established that radiation-chemical yields of CO2 and H2O2 are equal to 0.18 and 3.6 molec/100eV. Irradiation leads to increasing of acidity, related with dechlorination of PCB molecules. A comparative study of the radiolysis of used transformer oil and oil containing PCB under the influence of gamma radiation was carried out. The pH-value dependence and concentration of hydrogen peroxide as a function of the absorbed dose was studied. It found that during the radiolysis of transformer oil containing PCB in the presence of dissolved oxygen, radiation-initiated oxidation of the oil takes place (formation of H2O2 and CO2, a decrease in the pH-value).

Usually the main problem face any investigation it how to determent a sample size, however, some considerations required in sample size to conduct the efficacy and make realistic well-researched before began study. This study aimed to determine the maximum possible sample size at different phases of clinical trials and attempt to achieve the best accuracy of the results. To achieve that the maximum sample size in different phases we found that the maximum sample size of phase I was (75) relies on largest response rate 20% and the minimal clinically important difference (MCID) 15%, and because the participants are healthy often that means 15% enough to show positive results of the transition to the second phase. for the phase II clinical trials; the maximum sample size was (388) depend on the error 5% and largest response rate 50% when the response rate should not be less than 20% according to the design used in this phase. Depend on the endpoint and hazard ratio in phase III clinical trials when the probability of survival of the treatment group equal to median of the probability of survival 50% we found that the maximum sample size (4796). For the phase IV the maximum sample size in different phases of clinical trials does not affect whatever the large of the population size and remains constant as large as possible size.