| 1. |
- Gopalakrishnan, Shyam, et al.
(författare)
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The population genomic legacy of the second plague pandemic
- 2022
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Ingår i: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 32:21, s. 4743-4751.e6
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Tidskriftsartikel (refereegranskat)abstract
- Human populations have been shaped by catastrophes that may have left long-lasting signatures in their genomes. One notable example is the second plague pandemic that entered Europe in ca. 1,347 CE and repeatedly returned for over 300 years, with typical village and town mortality estimated at 10%–40%.1 It is assumed that this high mortality affected the gene pools of these populations. First, local population crashes reduced genetic diversity. Second, a change in frequency is expected for sequence variants that may have affected survival or susceptibility to the etiologic agent (Yersinia pestis).2 Third, mass mortality might alter the local gene pools through its impact on subsequent migration patterns. We explored these factors using the Norwegian city of Trondheim as a model, by sequencing 54 genomes spanning three time periods: (1) prior to the plague striking Trondheim in 1,349 CE, (2) the 17th–19th century, and (3) the present. We find that the pandemic period shaped the gene pool by reducing long distance immigration, in particular from the British Isles, and inducing a bottleneck that reduced genetic diversity. Although we also observe an excess of large FST values at multiple loci in the genome, these are shaped by reference biases introduced by mapping our relatively low genome coverage degraded DNA to the reference genome. This implies that attempts to detect selection using ancient DNA (aDNA) datasets that vary by read length and depth of sequencing coverage may be particularly challenging until methods have been developed to account for the impact of differential reference bias on test statistics.
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| 2. |
- Liu, Hang, et al.
(författare)
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Investigation of Nd3+ incorporation in Ce-rhabdophane : Insight from structural flexibility and occupation mechanism
- 2022
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Ingår i: Journal of The American Ceramic Society. - : John Wiley & Sons. - 0002-7820 .- 1551-2916. ; 105:7, s. 4974-4985
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Tidskriftsartikel (refereegranskat)abstract
- LnPO(4)center dot 0.667H(2)O rhabdophane has been considered as a potential material for the precipitation of actinides from radioactive waste liquid, owing to its outstanding characteristics of high actinide bearing and easy synthesis in acid solutions. However, a comprehensive understanding of the actinide occupation and the precipitation response of rhabdophane to remove actinides has yet to be established. In this study, the effect of ions concentration and pH values on the detailed precipitation reaction of CexNd1-xPO4 center dot 0.667H(2)O rhabdophane in acid solutions are systematically investigated. Some specific issues such as structural distortion and flexibility, and occupation mechanism are discussed by combining with experiments and density functional theory (DFT) calculation. The results reveal that ions concentration and pH values have a significant impact on the crystallization nucleation step before 12 h. The obtained removal rate of Nd3+ is more than 99% in pH 1-5 solutions with the ions concentration of 0.05-0.1 mol/L. Moreover, incorporating Nd in CePO4 center dot 0.667H(2)O rhabdophane will easily result in the lattice distortion in b-axis. DFT calculation and X-ray photoelectron spectroscopy (XPS) results reveal that Nd is preferentially incorporated in nonhydrated site to form a weaker binding energy of NdO8 polyhedron.
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| 3. |
- Ye, Mingliang, et al.
(författare)
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Preparation and properties of situ-sintered SiC ceramics aided by ZnO-Al2O3-CaO
- 2022
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Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 890
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Tidskriftsartikel (refereegranskat)abstract
- The safe treatment and disposal of radioactive graphite waste is becoming an important issue worldwide. The objective of this paper is to prepare the SiC-ZAC (ZAC: ZnO-Al2O3-CaO) composite ceramic for immobilizing radioactive graphite, where ZAC is as sintering additives. The effects of the sintering system and ZAC content on the phase compositions, microstructure, and properties of SiC-ZAC composite ceramic are studied by XRD, SEM-EDS, TEM-EDS, linear shrinkage, Vickers hardness, and thermal conductivity. By vacuum hot pressing sintering at 1600 degrees C for 1 h, the results show that the S-35-160 0 (65 wt% SiC, 10.5 wt% ZnO, 15.72 wt% Al2O3, 8.78 wt% CaO) sample is the potentially applicable formula composition due to its better performance, in which the Vickers hardness and the thermal conductivity are 165.2 HV10, 14.6 W m(-1) k(-1) respectively, and the normalized elemental mass loss of Si, Al and Ca are 0.0064-0.0108 g/m(2), 21.4784-24.7837 g/m(2), 56.9108-67.5637 g/m(2) after 42 days at pH = 5/7/9 solution, respectively. Importantly, ZAC sintering additives can form the bond phases of CaAl4O7, CaAl2O4, Ca3Al2(OH)(12), and Ca2Al2SiO7 under relatively low temperatures to reduce the sintering temperature for SiC ceramics. Meanwhile, the existing form of the Zn element is revealed: one part of the Zn forms glass phase, and the other part volatilized by carbothermic reduction.
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| 4. |
- Zhao, Xiaofeng, et al.
(författare)
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Exploring the relationship between Ln leaching and Ln-O binding energy in monazite (Nd, Sm, Eu)
- 2022
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Ingår i: Journal of The American Ceramic Society. - : John Wiley & Sons. - 0002-7820 .- 1551-2916. ; 105:1, s. 553-563
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the chemical durability of waste forms is important for the long-term deep geological disposal of actinides. However, in-depth investigations on the leaching mechanism of monazite ceramic waste forms remain to be poorly understand. Inspired by the degradation process of Ce-monazite controlled by the fracture of Ce-O bond of (010) surface under the action of permeable water molecules, the relationship between Ln leaching and Ln-O binding energy in LnPO(4) (Ln = Nd, Sm, Eu) monazites is investigated by combining dissolution experiments and first-principles calculations. The dissolution experiments are performed in 0.001 mol/L HCl solutions at 363 K. Before and after leaching, the phase compositions of specimens are carefully investigated by refined XRD and GIXRD, and the results confirm that the dissolved phases in contact with the leachate are LnPO(4) monazite. Some specific issues are discussed in detail by first-principles calculations, such as the bond length, charge transfer, electron localization function, and chemical bond properties. Moreover, the boundary conditions of crystal-growing of LnPO(4) monazite are investigated to define the chemical potential that is used to calculate the defect formation energy (Ef) of Ln vacancy in (010) surface. Importantly, the Ef results show the difficulty order of forming a vacancy defect of Ln on (010) surface is Eu > Sm > Nd, which is consistent with the leaching stability of Ln in LnPO(4) (Ln = Nd, Sm, Eu) monazite.
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