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Cerium-144 (144Ce), as a long-lived β emitter radioisotope (Eβavg = 82.25 keV, T1/2 = 284.9 d), is a potentially promising radionuclide to be used in various medical and industrial applications. In this paper, an optimized process for the separation of 144Ce from fission products is reported. Following the MCNPX calculation results, an equivalent solution was experimentally prepared that is similar to the waste solution of local 99Mo production via the fission method. For analyzing the steps of the radiochemical process, the suitable radioisotope tracers created from the activation method and were added to the simulated waste solution. The oxidation/reduction potential of Ce3+/Ce4+ together with extraction chromatography was exploited to achieve high yields of more than 70% and a reasonable radionuclidic purity of 97% and radiochemical purity of more 99% of radiocerium. [ABSTRACT FROM AUTHOR]

Radio immunotherapy is one of the most important and effective therapies for B-cell non Hoddgkin’s lymphoma treatment. Today, anti CD-20 antibodies labeled with beta emitter radionuclides are used in radio immunotherapy. Various radionuclides for labeling anti CD-20 antibodies have been studied and developed for the treatment and diagnosis of malignancies. This paper describes the preparation, bio-distribution and absorbed dose rate of 111In, 90Y, 177Lu, and 153Sm labeled anti CD-20 antibodies (rituximab) in human organs, after injection to rats. The macro cyclic bifunctional chelating agent, N-succinimidyl-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA-NHS) for conjugation to antibody, was used to prepare DOTA-rituximab. The conjugates were purified by molecular filtration, the average number of DOTA conjugated per mAb was calculated and total concentration was determined by spectrophotometric method. Radio-labeling was performed at 40 °C for 24 hours. After the quality control studies, the final radioactive solution was injected intravenously into rats through their tail vein. The tissue uptakes of each injection were measured. Then we calculated S values for 177Lu and 153Sm by using specific absorbed fractions and data used in the manner of radio-labeled analysis and dosimetry for humans. The absorbed dose rate of each organ was calculated in the specific time by medical internal radiation dose method with linear approximation in the activity measurements.

In this study, optimized preparation, quality control, cell assessments and biostribution of 188Re-HYNIC-PSMA in normal rats and tumor bearing mice are studied. Optimized conditions for radiolabeling were evaluated and radiochemical purity (> 99%) was investigated using ITLC and HPLC methods. 188Re-HYNIC-PSMA was stable both in PBS (4 °C) and in human serum (37 °C) even after 48 h. The results showed the complex was cleared from the blood very fast via urinary track. This new radiolabeled compound has a high potential to be considered as an agent for the treatment of patients with PSMA expressing tumors however more biological studies are still needed. [ABSTRACT FROM AUTHOR]

Molybdenum-99 and some other fission products such as promethium-147 are formed by the fission of 235U. Applying an efficient separation approach, the 147Pm can be isolated. The production of 147Pm as a by-product of previously optimized conditions for fission molybdenum-99 process is precisely evaluated. Considering the numerous radionuclides with various half-lives accompanying the 147Pm as impurities, a precise time window can be determined to perform an efficient separation process. The fission products activity calculations, using MCNPX and ORIGEN2.1 computer codes, were performed to achieve such a proper time window. Here, it is shown that 300 days after the end of bombardment (EOB), the radioactivity of the other radionuclides is reduced to 1% of 147Pm radioactivity. The chemical process needed to separate the remaining radionuclides is then explained in detail. [ABSTRACT FROM AUTHOR]

Tea plantations cover an area of ca. 31,000 ha in the Central North of Iran. This area, after clearing the original forests more than 50 years ago, became exposed to severe soil erosion. The objective of this study was to assess long-term soil erosion rates in tea farms and to evaluate their soil conservation effect at a whole-of-catchment scale. No previous information on direct measurements of soil erosion in this mountainous tea agro-ecosystem of Northern Iran is available. Point-based estimates of net erosion have been obtained using the 137Cs technique and these results were compared with estimates using the RUSLE model. Calculations of soil erosion rates from 137Cs inventories, based on the Mass Balance Model II, revealed that 1.3 mm year−1 and 1.45 mm year−1 of soils were lost from the two sub-catchments A1 and A2, into which the catchment can be divided. The annual net erosion rate of the entire catchment was 17.06 t ha−1 year−1 which is consistent with the rate of 20.4 t ha−1 year−1 obtained by the RUSLE model of at the same scale. This study suggests adopting soil conservation practices to control soil erosion, especially after deforestation and periodic pruning of tea bushes. Sustainable land-use plans are then necessary for tea farms of Iran to protect soil resources and to reduce the off-site impacts of land degradation (mainly siltation) on the reservoirs and coastal area. [ABSTRACT FROM AUTHOR]

In this study, a possible therapeutic agent was developed owning to attractive characteristic of 166Dy/166Ho in-vivo generator and tumor targeting of 5,10,15,20-tetrakis(phenyl)porphyrin (TPP). ITLC of the final formulation indicated RCP more than 97%, and excellent stability in room temperature and presence of human serum was obtained for 48 h. No daughter radionuclide recoil was observed. Biodistribution data showed the rapid excretion from urinary tract, and less extends from liver. Due to the advantages of in-vivo generators like high dose delivery in target tissue with less damage to normal ones and the obtained suitable results of radiolabeling of 166Dy/166Ho-TPP, a possible agent as a fascinating tumor-targeting was suggested. [ABSTRACT FROM AUTHOR]