Complex population genetic and demographic history of the Salangid, Neosalanx taihuensis, based on cytochrome b sequences

<p>Abstract</p> <p>Background</p> <p>The Salangid icefish <it>Neosalanx taihuensis </it>(Salangidae) is an economically important fish, which is endemic to China, restricted to large freshwater systems (e.g. lakes, large rivers and estuaries) and typically exhibit low vagility. The continuous distribution ranges from the temperate region of the Huai and Yellow River basins to the subtropical region of the Pearl River basin. This wide ranging distribution makes the species an ideal model for the study of palaeoclimatic effects on population genetic structure and phylogeography. Here, we aim to analyze population genetic differentiation within and between river basins and demographic history in order to understand how this species responded to severe climatic oscillations, decline of the sea levels during the Pleistocene ice ages and tectonic activity.</p> <p>Results</p> <p>We obtained the complete mtDNA cytochrome <it>b </it>sequences (1141 bp) of 354 individuals from 13 populations in the Pearl River, the Yangze River and the Huai River basin. Thirty-six haplotypes were detected. Haplotype frequency distributions were strongly skewed, with most haplotypes (n = 24) represented only in single samples each and thus restricted to a single population. The most common haplotype (H36) was found in 49.15% of all individuals. Analysis of molecular variance (AMOVA) revealed a random pattern in the distribution of genetic diversity, which is inconsistent with contemporary hydrological structure. Significant levels of genetic subdivision were detected among populations within basins rather than between the three basins. Demographic analysis revealed that the population size in the Pearl River basin has remained relatively constant whereas the populations in the Yangze River and the Huai River basins expanded about 221 and 190 kyr ago, respectively, with the majority of mutations occurring after the last glacial maximum (LGM).</p> <p>Conclusion</p> <p>The observed complex genetic pattern of <it>N. taihuensis </it>is coherent with a scenario of multiple unrelated founding events by long-distance colonization and dispersal combined with contiguous population expansion and locally restricted gene flow. We also found that this species was likely severely impacted by past glaciations. More favourable climate and the formation of large suitable habitations together facilitated population expansion after the late Quaternary (especially the LGM). We proposed that all populations should be managed and conserved separately, especially for habitat protection.</p

Karriere-Handbuch

We design and synthesize four fused-ring electron acceptors based on 6,6,12,12-tetrakis(4-hexylphenyl)- indacenobis(dithieno[3,2-b;2′,3′-d]thiophene) as the electron- rich unit and 1,1-dicyanomethylene-3-indanones with 0− 2 fluorine substituents as the electron-deficient units. These four molecules exhibit broad (550−850 nm) and strong absorption with high extinction coefficients of (2.1−2.5) × 105 M−1 cm−1. Fluorine substitution downshifts the LUMO energy level, red-shifts the absorption spectrum, and enhances electron mobility. The polymer solar cells based on the fluorinated electron acceptors exhibit power conversion efficiencies as high as 11.5%, much higher than that of their nonfluorinated counterpart (7.7%). We investigate the effects of the fluorine atom number and position on electronic properties, charge transport, film morphology, and photovoltaic properties

Single-Junction Binary-Blend Nonfullerene Polymer Solar Cells with 12.1% Efficiency

A new fluorinated nonfullerene acceptor, ITIC-Th1, has been designed and synthesized by introducing fluorine (F) atoms onto the end-capping group 1,1-dicyanomethylene-3-indanone (IC). On the one hand, incorporation of F would improve intramolecular interaction, enhance the push–pull effect between the donor unit indacenodithieno[3,2-b]thiophene and the acceptor unit IC due to electron-withdrawing effect of F, and finally adjust energy levels and reduce bandgap, which is beneficial to light harvesting and enhancing short-circuit current density (JSC). On the other hand, incorporation of F would improve intermolecular interactions through C-F···S, C-F···H, and C-F···π noncovalent interactions and enhance electron mobility, which is beneficial to enhancing JSC and fill factor. Indeed, the results show that fluorinated ITIC-Th1 exhibits redshifted absorption, smaller optical bandgap, and higher electron mobility than the nonfluorinated ITIC-Th. Furthermore, nonfullerene organic solar cells (OSCs) based on fluorinated ITIC-Th1 electron acceptor and a wide-bandgap polymer donor FTAZ based on benzodithiophene and benzotriazole exhibit power conversion efficiency (PCE) as high as 12.1%, significantly higher than that of nonfluorinated ITIC-Th (8.88%). The PCE of 12.1% is the highest in fullerene and nonfullerene-based single-junction binary-blend OSCs. Moreover, the OSCs based on FTAZ:ITIC-Th1 show much better efficiency and better stability than the control devices based on FTAZ:PC71BM (PCE = 5.22%)

Baiji genomes reveal low genetic variability and new insights into secondary aquatic adaptations

The baiji, or Yangtze River dolphin (Lipotes vexillifer), is a flagship species for the conservation of aquatic animals and ecosystems in the Yangtze River of China; however, this species has now been recognized as functionally extinct. Here we report a high-quality draft genome and three re-sequenced genomes of L. vexillifer using Illumina short-read sequencing technology. Comparative genomic analyses reveal that cetaceans have a slow molecular clock and molecular adaptations to their aquatic lifestyle. We also find a significantly lower number of heterozygous single nucleotide polymorphisms in the baiji compared to all other mammalian genomes reported thus far. A reconstruction of the demographic history of the baiji indicates that a bottleneck occurred near the end of the last deglaciation, a time coinciding with a rapid decrease in temperature and the rise of eustatic sea level

Kinematic calibration of a 6-DOF hybrid robot by considering multicollinearity in the identification Jacobian

This paper presents a systematic approach for the kinematic calibration of a 6-DOF hybrid polishing robot. It concentrates particularly on dealing with ill-conditioning that arises from multicollinearity in the identification Jacobian as a consequence of limited pose measurements. A linearized error model is formulated, using screw theory, by considering all possible source errors at the joint/link level. Calibration is based upon pose error measurements captured using a laser tracker when the polishing head undergoes pure translation within the task workspace. A two-step procedure for error parameter estimation and pose error compensation is then proposed: (1) coarse estimation and compensation of the encoder offsets using linear least squares; and (2) fine estimation of the whole set of identifiable error parameters using a Liu estimation and subsequent modification of the NC trajectory dataset of the polishing head. Both simulations and experiments on a prototype machine show that the overall standard deviation of the error parameters identified by Liu estimator is much less than that estimated by linear least squares, confirming its greater robustness in the presence of measurement uncertainty. The proposed approach results in satisfactory pose accuracy of the polishing head throughout the entire task workspace

In-Situ AlN Induced Valence State Variation of V in Vanadium Oxide Films Investigated by XPS

Vanadium oxide (VOx) thin films with and without in situ AlN layer were grown on single crystal sapphire substrates by pulsed laser deposition (PLD) with V2O5 target. The significant structure and morphology transforms resulted from the insertion of in-situ AlN layer were observed by X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM). To interpret the mechanism behind these phenomena, the valence state variation of vanadium (V) in VOx films induced by in-situ AlN layer was investigated by X-ray photoelectron spectroscopy (XPS) analyses. The results indicated that the valence state of V become more complicated and VOx films with the mixed V valence state of V5+,V4+and V3+ were obtained due to the introduction of AlN interfacial stress layer. Our achievements will be helpful for understanding the physical mechanism behind the exotic characteristics of VOx films induced by stress layer

Emerging Approaches in Enhancing the Efficiency and Stability in Non-Fullerene Organic Solar Cells

The past three years have witnessed rapid growth in the field of organic solar cells (OSCs) based on non-fullerene acceptors (NFAs), with intensive efforts being devoted to material development, device engineering, and understanding of device physics. The power conversion efficiency of single-junction OSCs has now reached high values of over 18%. The boost in efficiency results from a combination of promising features in NFA OSCs, including efficient charge generation, good charge transport, and small voltage losses. In addition to efficiency, stability, which is another critical parameter for the commercialization of NFA OSCs, has also been investigated. This review summarizes recent advances in the field, highlights approaches for enhancing the efficiency and stability of NFA OSCs, and discusses possible strategies for further advances of NFA OSCs.Funding Agencies|National Natural Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [21704021, 21805288]; European Commission Marie Skodowska-Curie action [843872]; Stiftelsen for Strategisk Forskning through a Future Research Leader program [FFL18-0322]; Swedish Research Council VRSwedish Research Council [2016-06146, 2018-05484, 2018-06048]; Swedish Energy AgencySwedish Energy Agency [43691-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009-00971]</p