| 1. |
- Feng, Shaohong, et al.
(author)
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Dense sampling of bird diversity increases power of comparative genomics
- 2020
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 587:7833
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Journal article (peer-reviewed)abstract
- Whole-genome sequencing projects are increasingly populating the tree of life and characterizing biodiversity(1-4). Sparse taxon sampling has previously been proposed to confound phylogenetic inference(5), and captures only a fraction of the genomic diversity. Here we report a substantial step towards the dense representation of avian phylogenetic and molecular diversity, by analysing 363 genomes from 92.4% of bird families-including 267 newly sequenced genomes produced for phase II of the Bird 10,000 Genomes (B10K) Project. We use this comparative genome dataset in combination with a pipeline that leverages a reference-free whole-genome alignment to identify orthologous regions in greater numbers than has previously been possible and to recognize genomic novelties in particular bird lineages. The densely sampled alignment provides a single-base-pair map of selection, has more than doubled the fraction of bases that are confidently predicted to be under conservation and reveals extensive patterns of weak selection in predominantly non-coding DNA. Our results demonstrate that increasing the diversity of genomes used in comparative studies can reveal more shared and lineage-specific variation, and improve the investigation of genomic characteristics. We anticipate that this genomic resource will offer new perspectives on evolutionary processes in cross-species comparative analyses and assist in efforts to conserve species. A dataset of the genomes of 363 species from the Bird 10,000 Genomes Project shows increased power to detect shared and lineage-specific variation, demonstrating the importance of phylogenetically diverse taxon sampling in whole-genome sequencing.
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| 2. |
- Chen, Xin, et al.
(author)
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Two-Dimensional Square-A(2)B (A = Cu, Ag, Au, and B = S, Se) : Auxetic Semiconductors with High Carrier Mobilities and Unusually Low Lattice Thermal Conductivities
- 2020
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In: The Journal of Physical Chemistry Letters. - : AMER CHEMICAL SOC. - 1948-7185. ; 11:8, s. 2925-2933
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Journal article (peer-reviewed)abstract
- Using evolutionary structure search combined with ab initio theory, we investigate the electronic, thermal, and mechanical properties of two-dimensional (2D) A(2)B (A = Cu, Ag, Au, and B = S, Se) auxetic semiconductors. Two types of structures are found to have low energy, namely, s(I/II)-A(2)B, which have direct bandgaps in the range 1.09-2.60 eV and high electron mobilities. Among these semiconductors, Cu2B and Ag2B have light holes with 2 orders of magnitude larger mobility than the heavy holes, up to 9.51 X 10(4)cm(2) v(-1) s(-1) , giving the possibility of achieving highly anisotropic hole transport with the application of a uniaxial strain. Due to the ionic bonding nature, s-A(2)B structures have unusually low lattice thermal conductivities down to 1.5 W m(-1) K-1 at 300 K, which are quite promising for new generation thermoelectric devices. Besides, s-A(2)B structures show extraordinary flexibility with ultralow Young's moduli (down to 20 N/m), which are lower than most previously reported 2D materials. Moreover, under strain along the diagonal direction, five of the structures have in-plane negative Poisson's ratios.
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| 3. |
- Ivanov, Sergey, et al.
(author)
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Partial cation ordering, relaxor ferroelectricity, and ferrimagnetism in Pb(Fe1-xYbx)(2/3)W1/3O3 solid solutions
- 2020
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In: Journal of Applied Physics. - : AMER INST PHYSICS. - 0021-8979 .- 1089-7550. ; 128:13
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Journal article (peer-reviewed)abstract
- The structural, magnetic, and dielectric properties of ceramic samples of Yb-doped PbFe2/3W1/3O3 have been investigated by a variety of methods including x-ray powder diffraction, magnetometry, and dielectric spectroscopy. In addition, theoretical investigations were made using first-principles density functional calculations. All the doped samples Pb(Fe1-xYbx)(2/3)W1/3O3 (PFYWO) (0.1 <= x <= 0.5) were found to crystallize in an ordered cubic ( F m 3 m ) structure with partial ordering in the B-perovskite sites. Observed changes in the cationic order were accompanied by differences in the dielectric and magnetic responses of the system. While pure PbFe2/3W1/3O3 is antiferromagnetic, the doped Pb(Fe1-xYbx)(2/3)W1/3O3 PFYWO samples display excess moments and ferrimagnetic-like behavior, associated with differences in B ' and B '' site occupancies of the magnetic Fe3+ cations. The magnetic transition temperature of the ferrimagnetic phase is found to decrease with increasing Yb content, from T-N similar to 350K of the undoped sample down to 137K for x=0.5. All PFYWO compounds display a ferroelectric relaxor behavior akin to that of PbFe2/3W1/3O3, albeit our results show significant changes of the frequency and temperature dependence of the dielectric properties. The changes of the properties of PFYWO with increasing Yb substitution can be explained by the changes in the cation size/charge mismatch and the size difference of the two ordered positions.
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| 4. |
- Tang, Xiaopeng, et al.
(author)
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Run-to-Run Control for Active Balancing of Lithium Iron Phosphate Battery Packs
- 2020
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In: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 35:2, s. 1499-1512
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Journal article (peer-reviewed)abstract
- © 1986-2012 IEEE. Lithium iron phosphate battery packs are widely employed for energy storage in electrified vehicles and power grids. However, their flat voltage curves rendering the weakly observable state of charge are a critical stumbling block for charge equalization management. This paper focuses on the real-time active balancing of series-connected lithium iron phosphate batteries. In the absence of accurate in situ state information in the voltage plateau, a balancing current ratio (BCR) based algorithm is proposed for battery balancing. Then, BCR-based and voltage-based algorithms are fused, responsible for the balancing task within and beyond the voltage plateau, respectively. The balancing process is formulated as a batch-based run-to-run control problem, as the first time in the research area of battery management. The control algorithm acts in two timescales, including timewise control within each batch run and batchwise control at the end of each batch. Hardware-in-the-loop experiments demonstrate that the proposed balancing algorithm is able to release 97.1% of the theoretical capacity and can improve the capacity utilization by 5.7% from its benchmarking algorithm. Furthermore, the proposed algorithm can be coded in C language with the binary code in 118 328 bytes only and, thus, is readily implementable in real time.
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