JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2005 | Volume:- | Issue:3 (35)|Papers Count:12

There is a mutual protection when mixtures of components irradiate together, thereby experimental investigations are necessary for determination of the effects that actually occur in different classes of nutrients in formulated foods. This work is concerned with the effect of g- irradiation on fatty acids content of a formulated baby food fat and the results are compared with the changes of fatty acids in the irradiated whole foods. The irradiation was performed with a gamma cell (Co-60) at the dose levels of 0.5, 1.5, 6, 10, 30, 45 kGy at room temperature and in the presence of air. The samples were analyzed immediately after the irradiation by a high performance liquid chromatography (HPLC). The results have shown that destruction of fatty acids in this formulated food is reasonably less than that of the fatty acids of the whole foods fat.

Several sets of dried vegetable and spices samples were prepared and weighed precisely due to the importance of the sample mass in EPR system response. The samples were irradiated under the 10 MeV electron beam with 10 kGy absorbed dose value. The EPR system was adjusted on the optimized EPR parameters. Then the EPR spectrums of the samples were measured. The measurements were repeated in a defined time intervals to investigate the stability amount of the free radicals. The effects of temperature and humidity on EPR response were also studied. Results were shown that the amounts of free radicals induced by radiation decrease and are eliminated after about two months. It was also obtained that the temperature and humidity which are the processes that occur upon using this materials like cooking time and increasing humidity, cause also to completely eliminate the created free radicals.

Banana belongs to Musaceae family and Musa genus, categorized as a plant growing in tropical and subtropical regions. In recent years, many attempts have been made for extending the cultivation of this plant in Iran. The cultivars, which are cultivating commonly in Iran are mostly Cavendish and Grand Nain, having rather long heights (2-4 meters). This research has been carried out aiming at determining the optimum dose rate to induce mutation in the banana plant shoot-tips. For this purpose the plant shoot-tips were exposed to various doses of gamma radiation with eight treatments of 0,10, 15, 20, 25, 35, 45 and 60 Gray. The project was directed in a completely randomized design. After the treatment, various traits such as: number of alive plants, number of leafs, plant height and wet weight have been measured. For the data analysis, SAS and MSTAT softwares have been used in order to evaluate the average values and variances of the output results for the further analysis and comparisons. The results indicate that the dose rates of 25 to 40 Gray are the optimum rate values for induction of the mutation in this plant. Also, the propit analysis shows that the dose rate of 39.8 Gray is at the point of LD50 (50% of the dead level).

We use the equivalent local form of Kisslinger optical potential to calculate the elastic differential cross section for the scattering of pions from Pb and C nuclei with the energy near to the (3,3) resonance region. For this range of energy the scattering amplitude depends on the complex phase shifts of the pion-nucleon interaction, arising from the spin and isospin degrees of freedom. We calculate the elastic differential cross section by using Born approximation. To get the acceptable results, it is necessary to use a distorted wave function instead of the usual plane wave form for the incident pions. This wave function has adjustable energy dependent parameters. By fitting the experimental and theoretical differential cross section, we have calculated the values of the parameters of our wave function and the optical potential parameters.

Application of low energy1251and103 Pd sources in prostate cancer brachytherapy has been considerably increased, recently. Accordingly, the Nuclear Research Center for Agriculture and Medicine (NRCAM) has selected the production of lO3Pdsource seeds and their characterization as one of its main objectives. In this investigation, we have calculated TG-43U1 dosimetry parameters for a source similar to the primary NRCAM design, using MCNP Monte Carlo computer code with F4, F6 and *F8 tallies.The results have been compared with the corresponding values reported in the literature and for most of the cases, all the three tallies and the reported values are in good agreement. It has been found that the F6 tally is about 20 times faster than *F8 tally without any considerable loss of accuracy. Therefore, it is concluded that for design analysis purposes, the F6 tally is adequately efficient to perform cumbersome recursive brachytherapy seed design calculations.

Iran Radiological Air Monitoring Center has measured the concentration of atmospheric 7Be at two stations located in Iran: Tehran (35o 41'), and Zahedan (29o 28') for duration of 4 years. The gamma emitting nuclides have been collected by high-volume air samplers and measured by gamma spectrometry. The results of the measured gamma emitting nuclides have shown that the cosmogenic 7Be is the only nuclide found in the air of Iran. 7Be is one of radioactive products of the bombardment of atmosphere by the cosmic rays. The data for the two sampling sites show seasonal variations in the concentration of 7Be. The 7Beconcentrations are the highest at each of these sites during the warm midyear months. An important factor in producing the peak concentrations of 7Be during the warmer month is the increased rates of the vertical transport within the troposphere that occurs during the warm seasons. The concentration of 7Bein air shows some difference between the obtained data in Tehran and Zahedan stations, with the respective values of 10.41±1.50E+00 mBqm-3 in Tehran and 17.10±1.90 E+00mBq m-3 in Zahedan. But the seasonal variations of 7Be concentration behavior are the same. We believe that 7Be concentration decreases poleward from the middle latitudes, because of the stability of the tropospheric air is the highest toward the cold polar region and decreases in the rate of vertical mixing within the troposphere.

Great Kavir basin is the largest inner basin in Iran that extended about 90000 km2.This basin is situated in the centre of Iran, to the south from Alborz mountain range and elongated in the sub latitudinal trend and its construction is asymmetric. The basin cover consists generally of complicated sequence of continental - marine Oligocene - Miocene molasses. According to drainage systems conditions, molassoid cycles, alluvial, alluvial- deltaic and lacustrine sediments, climate, morphological conditions and metallogenic and structural features, Great Kavir depression generally is favorable for exogenic and surficial uranium deposits (vally-fill, flood plain, deltaic and playa). Uranium occurrences that are known in the southern and north eastern part of the margent Great Kavir basin, are Arosan, Irekan and Mohammad Abad. Similar geological - structural conditions for uranium mineralization is possible in the margent of Great Kavir basin.

Thallium-203 is the main material for 201TICl3 radiopharmaceutical. It is very important to recover the remaining enriched Thallium-203 in every stage of the process to be reused in the production loop. In this research, the recuperation of Thallium-203 was studied with Dowex 50WX8 ion exchange resin and Thallium-201 as a tracer. The results based on filling of (18x1.5) cm columns with this resin showed that the best flow rate of eluent is 2 mL/min. Also the most suitable volumes are {200 mL (RNO3 0.05 M), 400 mL (solution of Thallium-203), 100 mL (H2O), 500 mL (Citric acid), 100 mL (H2O), 100 mL (EDTA 0.5 M &pH~12.5), 60 mL (H2O), respectively.