The origin of Tibetans remains one of the most contentious puzzles in history, anthropology, and genetics. Analyses of deeply sequenced (30×-60×) genomes of 38 Tibetan highlanders and 39 Han Chinese lowlanders, together with available data on archaic and modern humans, allow us to comprehensively characterize the ancestral makeup of Tibetans and uncover their origins. Non-modern human sequences compose ∼6% of the Tibetan gene pool and form unique haplotypes in some genomic regions, where Denisovan-like, Neanderthal-like, ancient-Siberian-like, and unknown ancestries are entangled and elevated. The shared ancestry of Tibetan-enriched sequences dates back to ∼62,000-38,000 years ago, predating the Last Glacial Maximum (LGM) and representing early colonization of the plateau. Nonetheless, most of the Tibetan gene pool is of modern human origin and diverged from that of Han Chinese ∼15,000 to ∼9,000 years ago, which can be largely attributed to post-LGM arrivals. Analysis of ∼200 contemporary populations showed that Tibetans share ancestry with populations from East Asia (∼82%), Central Asia and Siberia (∼11%), South Asia (∼6%), and western Eurasia and Oceania (∼1%). Our results support that Tibetans arose from a mixture of multiple ancestral gene pools but that their origins are much more complicated and ancient than previously suspected. We provide compelling evidence of the co-existence of Paleolithic and Neolithic ancestries in the Tibetan gene pool, indicating a genetic continuity between pre-historical highland-foragers and present-day Tibetans. In particular, highly differentiated sequences harbored in highlanders' genomes were most likely inherited from pre-LGM settlers of multiple ancestral origins (SUNDer) and maintained in high frequency by natural selection.

The failure mechanism of graphite/LiNi 0.5 Mn 1.5 O 4 cells cycled at 25 • C and 55 • C have been analyzed by electrochemical methods and ex-situ surface analysis of the electrodes. Graphite /LiNi 0.5 Mn 1.5 O 4 cells cycle well at 25 • C, but have rapid capacity fade upon cycling at 55 • C. Independent electrochemical analysis of anodes and cathodes extracted from cells cycled at 55 • C suggest that both electrodes have significant capacity loss, although the cathode capacity can be recovered with longer charging times. Ex-situ surface analysis of the cathode with SEM reveals that the bulk cathode particles and the cathode laminate are retained while XPS confirms the presence of a cathode electrolyte interface composed of the decomposition products of the electrolyte. Ex-situ analysis of the anode reveals a thick anode solid electrolyte interphase (SEI), anode delamination, and the presence of Mn. The results suggest that both the anode and the cathode contribute to performance loss in graphite/LiNi 0.5 Mn 1.5 O 4 cells.

BackgroundHan Chinese, Japanese and Korean, the three major ethnic groups of East Asia, share many similarities in appearance, language and culture etc., but their genetic relationships, divergence times and subsequent genetic exchanges have not been well studied.ResultsWe conducted a genome-wide study and evaluated the population structure of 182 Han Chinese, 90 Japanese and 100 Korean individuals, together with the data of 630 individuals representing 8 populations wordwide. Our analyses revealed that Han Chinese, Japanese and Korean populations have distinct genetic makeup and can be well distinguished based on either the genome wide data or a panel of ancestry informative markers (AIMs). Their genetic structure corresponds well to their geographical distributions, indicating geographical isolation played a critical role in driving population differentiation in East Asia. The most recent common ancestor of the three populations was dated back to 3000 ~ 3600 years ago. Our analyses also revealed substantial admixture within the three populations which occurred subsequent to initial splits, and distinct gene introgression from surrounding populations, of which northern ancestral component is dominant.ConclusionsThese estimations and findings facilitate to understanding population history and mechanism of human genetic diversity in East Asia, and have implications for both evolutionary and medical studies.Electronic supplementary materialThe online version of this article (10.1186/s41065-018-0057-5) contains supplementary material, which is available to authorized users.

Electrochemical impedance spectra (EIS) of Li+ insertion in spinel Li x Mn2O4 (0 ≤ x ≤ 1) were obtained by using a powder microelectrode. A new equivalent circuit, distinguishing the kinetic properties of Li+ insertion in Li x Mn2O4 at a lithium-rich state (0.5 ≤ x ≤ 1) from a lithium-depleted state (0 ≤ x < 0.5), is proposed to simulate the experimental EIS. The fitting results are in good agreement with the experimental results, and parameters for the kinetic process of Li+ insertion in Li x Mn2O4 at different Li+ inserted states can be obtained with the proposed equivalent circuits as well as the modified Voigt−FMG equivalent circuit proposed by Aurbach et al. At the lithium-depleted state, Li+ ions diffuse rapidly and then occupy the available Li+ insertion sites in the Li x Mn2O4 lattice. Thus, the diffusion process and occupation process occur successively at the lithium-depleted state, and this process can be well-simulated with the modified Voigt−FMG equivalent circuit, in which Warburg impedance and occupation capacitance are in series. At the lithium-rich state, however, the diffusion speed of the Li+ ions decreases due to the repulsive effect from the inserted Li+ ions. The diffusion of Li+ ions in the lattice takes place at the same time of the occupation of Li+ ions because the inserted Li+ ions have to hop and occupy their nearest neighbor vacant sites and vacate their sites for the incoming Li+ ions. Thus, the diffusion process and occupation process occur simultaneously, and Warburg impedance and occupation capacitance should be in parallel. The change of kinetic parameters of Li+ insertion in Li x Mn2O4 with potential and the influence of immersion time for Li x Mn2O4 in the electrolyte on the kinetic parameters are discussed in detail.

The Uyghur people residing in Xinjiang, a territory located in the far west of China and crossed by the Silk Road, are a key ethnic group for understanding the history of human dispersion in Eurasia. Here we assessed the genetic structure and ancestry of 951 Xinjiang's Uyghurs (XJU) representing 14 geographical subpopulations. We observed a southwest and northeast differentiation within XJU, which was likely shaped jointly by the Tianshan Mountains, which traverses from east to west as a natural barrier, and gene flow from both east and west directions. In XJU, we identified four major ancestral components that were potentially derived from two earlier admixed groups: one from the West, harboring European (25-37%) and South Asian ancestries (12-20%), and the other from the East, with Siberian (15-17%) and East Asian (29-47%) ancestries. By using a newly developed method, MultiWaver, the complex admixture history of XJU was modeled as a two-wave admixture. An ancient wave was dated back to ∼3,750 years ago (ya), which is much earlier than that estimated by previous studies, but fits within the range of dating of mummies that exhibited European features that were discovered in the Tarim basin, which is situated in southern Xinjiang (4,000-2,000 ya); a more recent wave occurred around 750 ya, which is in agreement with the estimate from a recent study using other methods. We unveiled a more complex scenario of ancestral origins and admixture history in XJU than previously reported, which further suggests Bronze Age massive migrations in Eurasia and East-West contacts across the Silk Road.

The cycling performance of Li/LiNi 0.5 Mn 1.5 O 4 cells with 1.0 M LiPF 6 in ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (3:7) with and without added dimethyl methylphosphonate (DMMP) (0.5-1.0%) was investigated. Addition of DMMP resulted in improved capacity retention during cycling to high voltage (4.9 V vs Li). Ex-situ surface analysis of LiNi 0.5 Mn 1.5 O 4 electrodes after cycling via Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Infrared (IR) spectroscopy suggest that addition of DMMP inhibits electrolyte decomposition on the surface of the cathode. Addition of DMMP also inhibits the dissolution of Mn from LiNi 0.5 Mn 1.5 O 4 particles stored in electrolyte at 85 • C.

Resonance Raman (RR) spectra of a series of water-soluble copper(I1) porphyrins mixed with DNA and synthetic oligonucleotides were measured by using CW and pulsed laser excitation. In CW excitation (406.7 and 441.6 nm), all the porphyrins mixed with these nucleic acids exhibit porphyrin core vibrations near 1570 and 1368 cm-I. Upon pulsed laser excitation (416 and 436 nm), some porphyrins mixed with nucleic acids containing ATAT sites exhibit extra bands at 1550 and 1346 cm-I, which originate in the transient exciplex formulated as Cu(porphyrin)*+(AT)-. Under proper experimental conditions, the populations of the ground-state porphyrins and the corresponding exciplexes become nearly equal. In the case of GC/CG intercalating porphyrins, this result suggests that some of these porphyrins are translocated from GC/CG to ATAT sites upon electronic excitation by pulsed laser. Three experiments were carried out, which supported the concept of translocation: (1) A typical GC/CG intercalator, Cu(TMpy-P4), was mixed with a 32-mer containing 26 possible GC/CG intercalation sites and only one ATAT site at the molar ratio of one porphyrin per two duplexes. Under these conditions, most of the porphyrins in their electronic ground states are expected to be intercalated at GC/CG sites. Yet, this solution exhibits a RR spectrum in which the exciplex bands are slightly stronger than the ground-state bands.(2) After Cu(TMpy-P4) was mixed with the 32-mer as in (l), a well-known AT site binder, Co(TMpy-P4), was added to the solution to block any unoccupied ATAT sites. Analysis of the pulsed laser RR spectrum of this solution reveals that at least 32% of the total porphyrin has been translocated from the GC/CG to an ATAT site. (3) The pulsed laser RR spectrum of Cu(TMpy-P4)-DNA at -85 *C indicates that the intensities of the exciplex bands have decreased markedly relative to those at room temperature. This observation suggests that some degree of molecular rearrangement is required to form the exciplex. Finally, the time scale of such translocatioin has been estimated and the biological significance of exciplex formation discussed. Observations have also been made regarding the enhanced photodegradation of DNA caused by this exciplex.

Tibetan high-altitude adaptation (HAA) has been studied extensively, and many candidate genes have been reported. Subsequent efforts targeting HAA functional variants, however, have not been that successful (e.g., no functional variant has been suggested for the top candidate HAA gene, EPAS1). With WinXPCNVer, a method developed in this study, we detected in microarray data a Tibetan-enriched deletion (TED) carried by 90% of Tibetans; 50% were homozygous for the deletion, whereas only 3% carried the TED and 0% carried the homozygous deletion in 2,792 worldwide samples (p < 10(-15)). We employed long PCR and Sanger sequencing technologies to determine the exact copy number and breakpoints of the TED in 70 additional Tibetan and 182 diverse samples. The TED had identical boundaries (chr2: 46,694,276-46,697,683; hg19) and was 80 kb downstream of EPAS1. Notably, the TED was in strong linkage disequilibrium (LD; r(2) = 0.8) with EPAS1 variants associated with reduced blood concentrations of hemoglobin. It was also in complete LD with the 5-SNP motif, which was suspected to be introgressed from Denisovans, but the deletion itself was absent from the Denisovan sequence. Correspondingly, we detected that footprints of positive selection for the TED occurred 12,803 (95% confidence interval = 12,075-14,725) years ago. We further whole-genome deep sequenced (>60×) seven Tibetans and verified the TED but failed to identify any other copy-number variations with comparable patterns, giving this TED top priority for further study. We speculate that the specific patterns of the TED resulted from its own functionality in HAA of Tibetans or LD with a functional variant of EPAS1.