A direct white-light metal-organic framework (MOF), [AgL](n) x nH(2)O (1, L = 4-cyanobenzoate), obtained by the reaction of deprotonated 4-cyanobenzoic acid and AgNO(3) in water, was found to exhibit tunable yellow-to-white photoluminescence by variation of excitation light. Interestingly, the close pure white emission of 1 has CIE-1931 chromaticity coordinates of (0.33, 0.34) when excited by 349-nm UV light, which is compatible to the light output of the deep UV LED.
Aim We aimed to examine the phylogeographical structure and demographic history of domestic and wild yaks (Bos grunniens) based on a wide range of samples and complete mitochondrial genomic sequences.
Location The Qinghai‐Tibetan Plateau (QTP) of western China.
Methods All available D‐loop sequences for 405 domesticated yaks and 47 wild yaks were examined, including new sequences from 96 domestic and 34 wild yaks. We further sequenced the complete mitochondrial genomes of 48 domesticated and 21 wild yaks. Phylogeographical analyses were performed using the mitochondrial D‐loop and the total genome datasets.
Results We recovered a total of 123 haplotypes based on the D‐loop sequences in wild and domestic yaks. Phylogenetic analyses of this dataset and the mitochondrial genome data suggested three well‐supported and divergent lineages. Two lineages with six D‐loop haplogroups were recovered for all morphological breeds of domestic yaks across their distributions in the QTP, while one more lineage and more endemic haplogroups or haplotypes were found for wild yaks. Based on the mitochondrial genome data, the divergences of the three lineages were estimated to have occurred around 420,000 and 580,000 years ago, consistent with the geological records of two large glaciation events experienced in the QTP.
Main conclusions There are distinct phylogeographical differences between wild and domestic yaks. However, there is no apparent geographical correlation between identified haplogroups and distributions of domestic yaks. Three differentiated lineages of yaks probably evolved allopatrically in different regions during the Pleistocene glaciation events, then reunited into a single gene pool during post‐glacial population expansion and migrations before the start of the domestication of yaks in the Holocene.
A big challenge for nonlinear optical (NLO) materials is the application in high power lasers, which needs the simultaneous occurrence of large second harmonic generation (SHG) and high laser induced damage threshold (LIDT). Herein we report the preparation of a new Ga2Se3 phase, which shows the SHG intensities of around 2.3 times and the LIDT of around 16.7 times those of AgGaS2 (AGS), respectively. In addition, its IR transparent window ca. 0.59–25 μm is also significantly wider than that of AGS (ca. 0.48–≈11.4 μm). The occurrence of the strong SHG responses and good phase‐matching indicate that the structure of the new Ga2Se3 phase can only be non‐centrosymmetric and have a lower symmetry than the cubic γ‐phase. The observed excellent SHG and phase‐matching properties are consistent with our diffraction experiments and can be well explained by using the orthorhombic models obtained through our high throughput simulations.
Wild yaks roaming in the high-altitude Qinghai-Tibetan plateau have to maintain high metabolic efficiency. However, domestic yaks do not require such high efficiency because of their limited activity. Hence, domestication may have caused the relaxation of selective constraints on the yak mitochondrial genome because mitochondrial mutations are extremely sensitive to energy-related selective pressures. We have tested this hypothesis by analyzing the mitochondrial genomes of 51 domestic yaks and 21 wild yaks. The results show that the ratio of nonsynonymous/synonymous substitutions in mitochondrial protein-coding genes is significantly higher in domestic yak lineages than those of wild yaks. This genetic difference suggests that the relaxation of selective constraints following the domestication in addition to bottlenecks has allowed faster accumulation of nonsilent substitutions in the yak mitochondrial genome, despite its short domestication history.
Four new quaternary isostructural rare-earth thiosilicates, ZnY(6)Si(2)S(14) (1), Al(0.50)Dy(3)(Si(0.50)Al(0.50))S(7) (2), Al(0.38)Dy(3)(Si(0.85)Al(0.15))S(7) (3), and Al(0.33)Sm(3)SiS(7) (4), crystallized in the chiral and polar space group P6(3), have been prepared by a facile synthetic routine. Compounds 1-3 show strong second harmonic generation effects at 2.1 um with the intensities of 1, 2, and 3 being about 2, 2, and 1 times that of KTP (KTiOPO(4)), respectively. The calculated band structure of 1 implies that the optical absorptions of BLn(6)M(2)Q(14) and ALn(3)MQ(7) family compounds are mainly ascribed to the charge transitions from Q-p to Ln-4f (4d for Y) states. Compounds 2-4 exhibit antiferromagnetic-like interactions.
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