JOURNAL OF NUCLEAR SCIENCE AND TECHNOLOGY
Year:2003 | Volume:- | Issue:28|Papers Count:11

In this study 23 bacterial strains were isolated, purified and investigated from samples of radioactive polluted water collected from different areas in Ramsar, soils of Hormoz Island, copper and molybdenum concentrated and various places of Copper Sarcheshmeh Mines. Among the isolated strains from samples that were investigated, isolated strains from soils of Copper Sarcheshmeh Mines showed their growth ability at the environment up to 1000 ppm molybdenum and presented a more adsorption ability of molybdenum in relation to other strains. In the pH adsorption study, the optimum value of pH =4 was selected. The effect of Mo-concentration in the adsorption process with 50 to 1000 ppm of Mo was investigated and the results shown that the highest adsorption is up to 200 ppm with 40% of molybdenum. In dynamics experiments of purified strains from soil samples of Copper Sarcheshmeh Mines showed that the biomasses were saturated almost 95% within 30 minutes. The average dry weight of bacterias were 0.1-0.7 gr per liter of environment and the adsorption capacity of biomasses varied from 50 to 304 mg Mo gr-1 dry biomasses. In comparison with the adsorption of resisting strains in high concentration of molybdenum with primary isolated strains were definite that the primary strains of 26-90% and resisting strains of 3-77% removed the molybdenum from 200 ppm. Therefore, the primary strains presented the higher adsorption capacity from the existing molybdenum which proved the occupation of some molybdenum adsorption sites on the surface of resisting bacterias cell on the adaptation time. Although there is still no proper definition about the mechanism of molybdenum adsorption, but by consideration of the optimum pH adsorption, we should state that the relative strains would mainly adsorb the kinds of polymeric anion and molybdate ions. The goal in the first stage of this research was to study the scope of molybdenum adsorption by isolated strains from soils of Copper Sarcheshmeh Mines and optimization of adsorption situation in the direction of providing radioisotope of molybdenum, which will be used in the nuclear medicine for diagnostic.

One of the suitable way to control the perennial weeds in the corn production is the application of selective herbicides. In order to study the best application time of 2,4-D to control red root weed and common lambsquarters an experiment was carried out at the Nuclear Research Center for Agriculture and Medicine in Karaj (2001-2002). Based on our research study, different growth stages of corn and two weeds were produced under the green house condition and all of plants were inoculated (after treating by 2,4-D) by labelled herbicide 2,4-D with activity of 0.05-0.12 µCi (in each 10 ml of solution), through the adaxial surface. The plants were harvested 48 hours after the treatment and divided into inoculated leaf, plant above and under the inoculated leaf. This study shows that 2-3 leaf stages of corn is the best application time of selective control of red root pigweed and common lambsquarters.

In this paper the effect of sterilization method by gamma-ray on structure and cytotoxicity of polyurethane film surface has been investigated. For this purpose reactive urethane prepolymer was synthesized by the reaction between TDI with a mixture of PEG and Castor oil (50/50, w/w). The cured prepolymer films were prepared due to the reaction of reactive prepolymer with air moisture under ambient conditions. The polyurethane films were sterilized by gamma-ray (25 kGy). The surface structure of sterilized polyurethane film was observed by SEM and compared to that of the unsterilized film. Also, the in vitro interaction of fibroblast L929 cells and sterilized polyurethane film was evaluated. Results showed no signs of cell toxicity.

Thin film thermopiles are widely used as small size sensors, in particular to sense infra-red thermal radiations. In this paper a method for designing and fabrication of thin films Bi-Cu thermopiles in linear array of 8 and 11 elements in series and mono-layer is introduced. Also, fabrication of Bi-Sb and Bi-Cu thin film thermopiles, which are used as IR radiation sensors, made in multilayer form with 100 series junctions in circular shape are presented. The samples are fabricated on a PCB board with double-sided copper laminated as a substrate. The results of our measurements show that the output voltage produced due to temperature difference between junctions, is very sensitive and linear to temperature difference

Separation of thallium isotopes (203Tl , 205Tl ) have been carried out by a 180o electromagnetic isotope separator. Thallium iodide as the charge material is used in a graphite crucible of calutron ion source. Under the pressure of 1 × 10-5 torr, thallium ions are extracted, accelerated and focused by the electrical lenses. The ions then traverse the main vacuum tank in circular paths, entering the magnetic field of 2547 Gauss and finally reach the collector. A number of chemical procedures have been employed for recovery and purification of the collected ions from the copper pockets. The final isotopic products have been characterized by a x-ray diffractometer, inductively coupled plasma-atomic emission spectrometer (ICP-AES) and a mass spectrometer. High pure thallium trioxide (Tl203 ) with 95.91% isotopic abundance for 203Tl has been confirmed.

Design, modeling and simulation of fluidized bed risers and reactors depend strongly on the knowledge, operational and hydrodynamic characteristics. In this study effort has been made to describe fluidization phenomenon and its application in fluidized beds is briefly explained. The bubble fluidized bed reactors will be introduced and the computerized calculation needed for simulating of a fluidized bed riser with 0.3m diameter and 5m height will be given. The effect of bed height on the bubble diameter and mass transfer area is calculated and the results are discussed. Operational conditions of the bed, type and characteristics of the catalyst, has been selected so as to suit the production of Maleic Anhydride from the n-Butane oxidation.

Coal tar pitch has a complex chemical structure. Determination of α; , β ,y fractions, is one of the methods to get information about its properties. In graphite fabrication it plays a role as a binder for coke particles. During the thermal treatment it carbonizes and changes to a secondary coke. This has considerable affects on the graphite properties. In this paper, determination of α , β, y and α1 fraction in three different types of pitches have been carried out. Graphite specimens have been fabricated by using these pitches and anisotropy coke in laboratory scale. The graphite properties have been compared with the nuclear grade graphite prototype. The comparison of the results showed that the density and compression strength are appreciable while the anisotropy factor of properties is about one. The linear thermal expansion in graphite from Iranian pitch had a better result, where it stands in the nuclear range of usage. As a result, our studies showed that the graphite properties are affected by properties of pitch fractions, where it can be used as a proper sample for the graphite fabrication

Lithogeochemical data (Cu, Mo, Fe, Co, Zn, Pb and S) for 293 surface samples in an area of lkm2 in the Daralu porphyry copper area were statisticaly analyzed. In order to identify the anomalous values from the background values, three statistical methods, namely, correlation coefficient, krigging, and principal component methods were used. The results obtained in this study indicate that copper mineralization is mainly confined to a granodiorite unit, and to a less extent to a rhyolite unit; but the highest correlation is related to the sericitic alteration.