SummaryWarm-temperate evergreen (WTE) forest represents the typical vegetation type of subtropical China, but how its component species responded to past environmental change remains largely unknown. Here, we reconstruct the evolutionary history of Tetrastigma hemsleyanum, an herbaceous climber restricted to the WTE forest.Twenty populations were genotyped using chloroplast DNA sequences and nuclear microsatellite loci to assess population structure and diversity, supplemented by phylogenetic dating, ancestral area reconstructions and ecological niche modeling (ENM) of the species distributions during the Last Glacial Maximum (LGM) and at present.Lineages in Southwest vs Central-South-East China diverged through climate/tectonicinduced vicariance of an ancestral southern range during the early Pliocene. Long-term stability in the Southwest contrasts with latitudinal range shifts in the Central-South-East region during the early-to-mid-Pleistocene. Genetic and ENM data strongly suggest refugial persistence in situ at the LGM.Pre-Quaternary environmental changes appear to have had a persistent influence on the population genetic structure of this subtropical WTE forest species. Our findings suggest relative demographic stability of this biome in China over the last glacial-interglacial cycle, in contrast with palaeobiome reconstructions showing that this forest biome retreated to areas of today's tropical South China during the LGM.
Aiming at the shortcomings of traditional research method of materials mechanics performance of concrete, this paper presents a new method to test the mechanical properties of concrete material layer body--the relative method. It focuses on the use of relative principle, testing dynamic elastic modulus of concrete damage layer subjected to single salt freezing cyclic, and draw a gradient damage curve of concrete, and then study the damage process of the concrete under the effect of salt solution and the freeze-thaw cycle synergetic factors. The method provides a new way to test body layer mechanical performance of concrete material which the traditional methods can not be directly solved.
Selecting lactam 2,6-pyridinedicarboxamide (PDCA) as the ligand and 1,4-butanediol as chain extender, we prepare polyurea polyurethane PDCA-PU; then, introduction of rare earth ion Eu3+ and small molecule ligands 1,10-phenanthroline (phen), synthesized binary and ternary polyurethane composite containing Eu3+, and comparing the fluorescence properties of the material. We investigated the thermal stability and luminescence properties of hybrids and found that the ternary hybrid materials exhibit better thermal stability and stronger emission intensity.
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