Study of ratio of tritium concentration in plants water to tritium concentration in air moisture for chronic atmospheric release of tritium

AbstractSpecific activity models (SA) are often used to estimate tritium concentration in the plants for chronic-release of atmospheric HTO in some regulatory models by some countries and commissions. In such models, a major assumption is that the value of specific activity of tritium of tritium oxide in vegetation to the specific activity of tritium of tritium oxide in air moisture is maintained at a constant ratio (R). The value of R is an important factor in determining tritium concentration and dose from chronic atmospheric release. But the value of R recommended is different from different models. Concentrations of tritium in plants will be have huge difference in plants because of the difference of the value of R, and this in turn would result in difference of ingestion dose via food chain. Some studies suggested that a site-specific distribution of R should be developed in suing a specific activity model. In this study, distribution of R is established for the Qinshan NPP Base. The environmental monitoring data of tritium concentration in five type plants (rapeseed, tea, cabbage, radish and rice) and air at three sampling points (Xiajiawan, Qinlian and Ganpu) around Qinshan NPP Base(QNNP) over a 4 years period as the basis for analysis, and the tritium ratio(R) between plant water and air moisture were determined. The results showed the average value of R of five plants were 0.103, 0.687, 1.055, 0.695 and 0.183 respectively. These values of R are mostly consistent with the law presented by foreign literature, only the value of R for cabbage is greater than the value of R for foliage vegetation presented by foreign reports. This is partly attributable to the difference of experimental conditions. The concentration of HTO of vegetations around QNNP could be assessed using the values of R recommended by this report for chronic release of atmospheric HTO

Comment on “A study on tetrahedron-based inhomogeneous Monte-Carlo optical simulation”

The Monte Carlo (MC) method is a popular approach to modeling photon propagation inside general turbid media, such as human tissue. Progress had been made in the past year with the independent proposals of two mesh-based Monte Carlo methods employing ray-tracing techniques. Both methods have shown improvements in accuracy and efficiency in modeling complex domains. A recent paper by Shen and Wang [Biomed. Opt. Express 2, 44 (2011)] reported preliminary results towards the cross-validation of the two mesh-based MC algorithms and software implementations, showing a 3–6 fold speed difference between the two software packages. In this comment, we share our views on unbiased software comparisons and discuss additional issues such as the use of pre-computed data, interpolation strategies, impact of compiler settings, use of Russian roulette, memory cost and potential pitfalls in measuring algorithm performance. Despite key differences between the two algorithms in handling of non-tetrahedral meshes, we found that they share similar structure and performance for tetrahedral meshes. A significant fraction of the observed speed differences in the mentioned article was the result of inconsistent use of compilers and libraries

Carbon Dioxide Improves Phosphorus Nutrition by Facilitating the Remobilization of Phosphorus From the Shoot Cell Wall in Rice (Oryza sativa)

Phosphorus (P) starvation leads to increased reutilization of cell wall P in rice (Oryza sativa). Carbon dioxide (CO2) is involved not only in plant growth and development but also in the response to abiotic stresses. However, it remains unclear whether CO2 affects the reutilization of cell wall P in rice when subjected to P deficiency. In the present study, elevated CO2 (600 μl·L−1) significantly increased the soluble P content in shoots when compared with ambient CO2 (400 μl·L−1). This positive effect was accompanied by an increase of pectin content, as well as an increase of pectin methylesterase (PME) activity, which results in P release from the shoot cell wall, making it available for plant growth. P deficiency significantly induced the expression of phosphate transporter genes (OsPT2, OsPT6, and OsPT8) and decreased the P content in the xylem sap, but elevated CO2 had no further effect, indicating that the increased soluble P content observed in shoots under elevated CO2 is attributable to the reutilization of shoot cell wall P. Elevated CO2 further increased the P deficiency-induced ethylene production in the shoots, and the addition of the ethylene precursor 1-amino-cyclopropane-1-carboxylic acid (ACC) mimicked this effect, while the addition of the ethylene inhibitor aminoethoxyvinylglycine (AVG) abolished this effect. These results further support the role of ethylene in the alleviation of P deficiency under elevated CO2. Taken together, our results indicate that the improvement of P nutrition in rice by elevated CO2 is mediated by increasing the shoot cell wall pectin content and PME activity, possibly via the ethylene signaling pathway

N-(4-hydroxyphenyl) retinamide inhibits migration of renal carcinoma cells and promotes autophagy via MAPK p38 pathway

Purpose: To investigate the effect of N-(4-hydroxyphenyl) retinamide (4HPR) on autophagy and migration of renal carcinoma cells.Methods: Renal cancer cell lines were treated with various concentrations of 4HPR. Proliferation of the cells was studied using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltrazolium bromide (MTT), while apoptosis and cell cycle arrest were determined by flow cytometry.Results: Treatment of RCCs with 30 μM 4HPR caused significant inhibition of viability. In 786-O and OS-RC-2 cell lines, 4HPR reduced colony formation by 39 and 43 %, respectively. In addition, 4HPR increased the percentage of 786-O cells in G1 phase from 58.79 ± 3.43 to 71.68 ± 4.47 % (p < 0.05). It also decreased the percentage of cells in the S-phase from 21.98 ± 2.78 to 09.17 ± 1.43 %, and enhanced the activation of p38 and JNK in 786-O cells at 48 h. Western blot assay showed that the activation of p38 and JNK by 4HPR was inhibited on pre-treatment with SB203580 (inhibitor of p38) and SP600125 (inhibitor of JNK), respectively. Reduction of 786-O cell viability by 4HPR treatment was also significantly inhibited by pre-treatment with sp203580 and sp600125 (p < 0.05). Furthermore, the inhibitors also reversed the effect of 4HPR on the expressions of Bax and Bcl-2 in 786-O cells.Conclusion: These results indicate that 4HPR inhibits the growth of renal cancer cells via activation of MAPK signalling pathway. Thus, 4HPR is a potential drug target for management of renal cancer.Keywords: Retinamide, Renal cancer, Autophagy, MAPK signalling, Cell proliferation, N-terminal kinas

Superconductivity at 22.3 K in SrFe2-xIrxAs2

By substituting the Fe with the 5d-transition metal Ir in SrFe2As2, we have successfully synthesized the superconductor SrFe2-xIrxAs2 with Tc = 22.3 K at x = 0.5. X-ray diffraction indicates that the material has formed the ThCr2Si2-type structure with a space group I4/mmm. The temperature dependence of resistivity and dc magnetization both reveal sharp superconducting transitions at around 22 K. An estimate on the diamagnetization signal reveals a high Meissner shielding volume. Interestingly, the normal state resistivity exhibits a roughly linear behavior up to 300 K. The superconducting transitions at different magnetic fields were also measured yielding a slope of -dHc2/dT = 3.8 T/K near Tc. Using the Werthamer-Helfand-Hohenberg (WHH) formula, the upper critical field at zero K is found to be about 58 T. Counting the possible number of electrons doped into the system in SrFe2-xIrxAs2, we argue that the superconductivity in the Ir-doped system is different from the Co-doped case, which should add more ingredients to the underlying physics of the iron pnictide superconductors.Comment: 4 pages, 4 figure

Superconductivity at 41.0 K in the F-doped LaFeAsO1-xFx

Here we report the superconductivity in the LaFeAsO1-xFx system prepared by high pressure synthesis. The highest onset superconducting transition temperature (Tc) in this La-based system is 41.0 K with the nominal composition of LaFeAsO1-xFx (x = 0.6), which is higher than that reported previously by ambient pressure synthesis. The increase of Tc can be attributed to the further shrinkage of crystal lattice that causes the stronger chemical pressure on the Fe-As plane, which is induced by the increased F-doping level under high pressure synthesis

High pressure study on LaFeAsO with different Tc

We report studies on pressure dependence of superconducting transition temperature (Tc) of LaFeAsO, LaFeAs(O0.5F0.5) and LaFeAs(O0.89F0.11) samples. In-situ resistance measurements under high pressure showed that the Tc of these three compounds increases with pressure initially, reaches a maximum value and then decreases with further increasing pressure, although the Tc at ambient pressure are different. The onset Tc of LaFeAsO is ~50 K at 1.5 GPa, which is the highest record in La-based oxypnicited system. The significant change in Tc induced by pressure is attributed to the orbital degeneracy and the electron density of state at the Fermi level.Comment: 13 pages, 4 figure