Estimation of atmospheric environmental radiation capacity in an isotope industrial park / 中国辐射卫生

Objective To study and estimate the public dose constraint and the atmospheric radiation capacity of an isotope industrial park, and to provide a basis for management of radioactive effluent discharge in isotope industrial parks. Methods We collected the natural environment data, meteorological data, and population distribution and dietary data as well as the source terms of radioactive airborne effluents of an isotope industrial park. The public dose constraint value of the isotope industrial park was determined based on the natural environmental radiation hazard level. The atmospheric environmental radiation capacity of the industrial park was estimated by the all-pathways method. Results The public dose constraint value of the industrial park was 0.2 mSv/a. At the end of industrial park planning, the maximum individual effective dose to the public caused by airborne effluent discharge was 1.07×10−6 Sv/a, which accounted for 0.54% of the public dose constraint value. The proportions of discharges of airborne radionuclides to respective environmental radiation capacities ranged from 0.04% to 4.34%. Conclusion The determined public dose constraint value of the isotope industrial park can be used as the total radiation capacity of the regional atmospheric environment to constrain the discharge of radioactive effluents. The environmental radiation capacity of each radionuclide can be estimated by the all-pathways method considering the comprehensive impact of radionuclide discharges, which is suitable for the control and management of isotope production enterprises in industrial parks.

Radiation dose estimation and protective measure discussion of 241Am-Be neutron source logging / 中国辐射卫生

Objective To investigate the radiation dose to operators in the process of 241Am-Be neutron source logging, and discuss neutron source management and protective measures for operators in well logging. Methods Through on-site observation and measurement of 241Am-Be neutron source logging in a company, we obtained the surface γ dose rate and neutron dose rate of the neutron source, as well as the operating time and distance of various processes including source taking, transfer, and loading, calculated the radiation dose to operators in various processes, and analyzed the source and proportion of the personal effective dose to operators. Results The effective doses of neutron irradiation and γ irradiation were 94.17 μSv and 2.72 μSv, respectively, for the combined processes of source tank inspection, transfer, and detection; 36.66 μSv and 24.08 μSv, respectively, for source loading and unloading; and 130.83 μSv and 26.80 μSv, respectively, for the whole neutron source logging process. The total annual effective dose of neutron source logging was 15.78 mSv, as estimated by logging 100 times per year. Conclusion In the process of 241Am-Be neutron source logging in the company, the effective dose to operators mainly arises from neutron irradiation. Therefore, it is necessary to strengthen neutron source management and take effective protective measures against neutron radiation.

Discussion of radiation shielding optimization for proton cyclotron therapy system plants / 中国辐射卫生

Objective To explore the radiation shielding optimization plan for a medical proton cyclotron developing and commissioning building at various commissioning stages. Methods According to the maximum source termsat different commissioning stages, we used the empirical formula to estimate the instantaneous dose rate at the point of interest outside the shield of the building, and optimized the building’s shielding ateach commissioning stage. Results When adding 1.0 m mobile concrete shielding blocks (“blocks” below) each to wall 3 and wall 4 at the cyclotron commissioning stage, 1.0 m blocks to wall 4 and 1.25 m blocks to wall 5 at the beam transport line commissioning stage, and 1.0 m blocks to wall 9 and 0.4 m blocks to the ceiling at the simulated treatment room commissioning stage, the dose rates at the points of interest outside the shield could meet the dose rate limit requirements. Conclusion The application of mobile concrete shielding blocks not only meets the shielding requirements, but also has economical and space-saving advantages, conforming to the principle of shielding optimization. This can be an approach to the optimization of radiation shielding for high-energy particle accelerators or similar scientific projects.

Radiation effects on residents caused by comprehensive utilization of slag in building materials / 中国辐射卫生

Objective This study intends to analyze the radioactivity level of slag and its building materials, estimate the effective dose of the residents caused by the comprehensive utilization of slag in building materials, and provide basis for rational utilization of slag. Methods Data of slag production and its comprehensive utilization in building materials, radioactive level investigation and detection of slag and building materials in different periods and regions were collected from 2005 to 2016. Using the room model of concrete structure and the model of calculating equilibrium equivalent radon concentration with the specific activity of 226Ra in indoor building materials, the external and internal radiation doses of residents caused by comprehensive utilization of slag for building materials were estimated respectively, and then the annual additional effective dose and collective dose of residents were estimated. Results The contents of 226Ra and 232Th in the slag were relatively high, while the contents of 40K were relatively low. The radionuclide content in slag cement decreased significantly. The annual additional effective doses of slag used in concrete and cement mixture relative to ordinary cement were 0.40 mSv·a−1 and 0.20 mSv·a−1 respectively. The annual additional collective dose and 50-year collective dose caused by slag used in building materials were 3.87 × 103～1.84 × 104 man·Sv and 1.94 × 105～9.20 × 105 man·Sv respectively. Conclusion The comprehensive utilization of slag in building materials increases the additional effective dose of residents, so the use of some slag in building materials needs to be paid more attention to. In addition, the influence of comprehensive utilization of slag in building materials, such as the way, the amount of slag and the amount of building materials, on the annual additional effective dose of residents caused should also be paid attention to.

Identification and characterization of rice OsCIPK10 gene / 生物工程学报

The preliminary role of calcineurin B-like protein-interacting protein kinases (CIPKs) in stress response is defined but the exact function of OsCIPK10 gene in rice stress response and its expression pattern yet unclear. In this study we explored the possible functions of OsCIPK10 gene by reverse genetics approaches and also revealed its expression pattern by GUS staining. From the preliminary study of this gene we presumed its function to assist plant to resist stress but over-expressed OsCIPK10 rice transgenic lines showed no significant phenotypic differences from the wild type either under high salt or low potassium conditions, however the gene knockdown plants using inverted repeat strategy presented meaningful healthy plants compared to wild type under the stress of salt. Further we checked the expression profile under high salt and low potassium conditions in wild type and found that OsCIPK10 decreases under high salt and increases on low potassium conditions. So we speculate that OsCIPK10 is actually going to function in response to high salt and low potassium stress. We also explored the expression pattern of this gene using Gus staining and found that gene expresses in all plant tissues, the only exception observed was its higher expression in the vascular tissues.

Analysis of rice OsPLD3 and OsPLD4 genes and promoters / 生物工程学报

Phospholipase Ds (PLDs) exist in many plants. PLDs catalyse the hydrolysis of phospholipids (e.g. phosphatidylcholine) in cell membrane into phosphatidic acid (PA) and polar free heads (e.g. choline). Two PLD members from rice, OsPLD3 and OsPLD4, were studied by reverse genetics approaches. The results showed that the promoters of OsPLD3 and OsPLD4 could drive the expression of the reporter gene in various tissues of the rice flower organs at different levels. The expression of both genes was induced by wounding and methyl jasmonate (MeJA), but with different intensity at different time intervals. No prominent phenotypes were observed by RNA interference with the gene-specific artificial miRNAs or over-expression of the target genes in rice plants, implying the functional redundancy among different members of the rice PLD family.

Cloning and function analysis of the rice small GTP-binding protein gene OsPra2 / 生物工程学报

Gene expression in rice roots under nutritional stress was studied using micro array techniques. The results showed that when re-supplied with sufficient amounts of nutrition after nutrition stress, the expression of OsPra2 (a small G protein which is homologous with Pea Pra2 protein) decreased in the plants root tissue. The cDNA sequence of the OsPra2 gene and its promoter, which is about 1 kb upstream of the translation origin point, was obtained using RT-PCR and PCR approaches. The OsPra2 protein contains four conserved GTP/GDP binding domains and specific domain of Rab small G protein family. The expression of OsPra2 and GST fusion protein in onion epidermal cells showed that OsPra2 protein was localized in the membrane and nucleus of the cell. The fusion expression of OsPra2 promoter and GUS reporter gene in transgenic rice suggested that the OsPra2 promoter allowed GUS expression in coleoptiles and roots. Compared with wild type rice, OsPra2 over expressed transgenic rice showed an obvious dwarf phenotype which resembles the BR deficient rice.