Correction to: Assessment of natural radioactivity in coals and coal combustion residues from a coal-based thermoelectric plant in Bangladesh: implications for radiological health hazards.

The original version of this article unfortunately contained an error in eq. 1. The denominator Ɛ of Eq. (1) was missing.

Assessment of natural radioactivity in coals and coal combustion residues from a coal-based thermoelectric plant in Bangladesh: implications for radiological health hazards.

To study the level of radioactivity concentrations from a coal-based power plant (Barapukuria, Bangladesh) and to estimate the associated radiological hazards, coal and associated combustion residuals from the power plant were analyzed by gamma-ray spectrometry with high-purity germanium (HPGe) detector. The results reveal that the mean radioactivity (Bq kg-1) concentrations in feed coal samples are 66.5 ± 24.2, 41.7 ± 18.2, 62.5 ± 26.3, and 232.4 ± 227.2 for U-238, Ra-226, Th-232, and K-40, respectively, while in coal combustion residuals (CCRs), they are 206.3 ± 72.4, 140.5 ± 28.4, 201.7 ± 44.7, and 232.5 ± 43.8, respectively. With the exception of K-40, all the determined natural radionuclides are considerably higher in the investigated feed coal and associated combustion residues as compared with the world soil and world coal mean activities. On the average, CCRs contains 3.10-3.37 times more natural radionuclides than the feed coal, except for K-40. The radioactivity of fly ash and bottom ash is fractionated, and ratio ranges from 1.40 to 1.57. The mean values of the radiological hazard indices in the coal and their associated residuals are 153.1 and 446.8 Bq kg-1 for radium equivalent activity, 0.41 and 1.21 for the external hazard index, 70 and 200.1 nGy h-1 for the absorbed gamma dose rate, 0.09 and 0.25 mSv year-1 for the annual effective dose rate, and 3.0 × 10-4 and 8.6 × 10-4 Sv-1 for the excess lifetime cancer risk, respectively, most of which exceed the UNSCEAR-recommended respective threshold limits. The outcome of this study suggests a potential radiological threat to the environment as well as to the health of occupational workers and nearby inhabitants from the examined samples.

Computational chemical analysis of Eu(iii) and Am(iii) complexes with pnictogen-donor ligands using DFT calculations.

We demonstrated density functional calculations of Eu(iii) and Am(iii) complexes with pnictogen-donor (X) ligands, (CH3)2X-CH2-CH2-X(CH3)2 (X = N, P, As and Sb). We investigated the optimized structures of the complexes and the Gibbs energy differences in the complex formation reactions. The results indicated that the N- and P-donor ligands exhibit Am(iii) ion selectivity over Eu(iii) ions; especially, the P-donor ligand showed the highest selectivity. The tendency of the Am(iii)/Eu(iii) selectivity by the pnictogen-donor ligands was found to be comparable to that of the soft acid classification in the hard and soft acids and bases rule. Mulliken's spin population analysis indicated that the bonding properties between the metal ion and the pnictogen atoms correlated with the Am(iii)/Eu(iii) selectivity. In particular, the participation of f-orbital electrons of the metal ion in the covalency was indicated to play an important role in the selectivity.

Bonding Study on the Chemical Separation of Am(III) from Eu(III) by S-, N-, and O-Donor Ligands by Means of All-Electron ZORA-DFT Calculation.

We performed a theoretical investigation for the selectivity of Eu(III)/Am(III) ions depending on the donor atoms by means of all-electron ZORA-DFT calculation. We estimated their selectivity as the relative stability in the complex formation reaction. The B2PLYP functional reproduced the experimental selectivity in which S- and N-donor ligands favor Am(III) ion, but O-donor ligand favors Eu(III) ion. Mulliken's bond overlap population analysis revealed that the contribution of the f orbital to the bonding was small or zero for Eu complex, whereas it was large for Am complex. The bonding nature of the f orbital for Am ion was the bonding type to S- and N-donor ligands, while it was the antibonding type to O-donor ligand. It was suggested that the difference in the bonding nature between the f orbital in the metal and the donor atoms determines the selectivity of Eu(III)/Am(III) by donor ligands.

Benchmark study of the Mössbauer isomer shifts of Eu and Np complexes by relativistic DFT calculations for understanding the bonding nature of f-block compounds.

We have performed benchmark investigations into the bonding properties in lanthanide and actinide complexes to quantitatively estimate the covalency of f-block compounds. Three different density functionals including BP86 (pure-GGA), B3LYP (hybrid-GGA) and B2PLYP (double hybrid-GGA) were employed for all-electron self-consistent field calculations compensated by the scalar-relativistic zero-order regular approximation (ZORA) Hamiltonian with a relativistically contracted all-electron basis set. Ten Eu and ten Np complexes were employed as benchmark sets for the calculation of Mössbauer parameters for (151)Eu and (237)Np compounds. As a result of the linear fitting between the calculated electron densities at the nucleus (ρ) and the experimental isomer shifts (δ(exp)), the calculations performed using the all-electron ZORA-B2PLYP level reproduced a change of electron density at the Mössbauer nucleus for both Eu and Np complexes with high correlation coefficients (R(2) > 0.90). Mulliken's population analyses indicated that the BP86 and B3LYP methods overestimated the covalency of both Eu and Np complexes due to the smaller amount of the exact Hartree-Fock exchange admixture included in BP86 and B3PLYP compared to that in the B2PLYP functional. By comparing Mulliken's electronic structure analyses with the experimental isomer shifts, we found that Mulliken's spin population values were good parameters to quantitatively estimate the bonding natures of Eu and Np complexes.

First successful ionization of Lr (Z = 103) by a surface-ionization technique.

We have developed a surface ionization ion-source as part of the JAEA-ISOL (Isotope Separator On-Line) setup, which is coupled to a He/CdI2 gas-jet transport system to determine the first ionization potential of the heaviest actinide lawrencium (Lr, Z = 103). The new ion-source is an improved version of the previous source that provided good ionization efficiencies for lanthanides. An additional filament was newly installed to give better control over its operation. We report, here, on the development of the new gas-jet coupled surface ion-source and on the first successful ionization and mass separation of 27-s (256)Lr produced in the (249)Cf + (11)B reaction.