26Al/10Be Age of Peking Man

The chronological position of Peking Man, or Homo erectus pekinensis, has long been pursued, but has remained problematic due to lack of a suitable dating method^1-7^. Here we report cosmogenic ^26^Al/ ^10^Be burial dating of quartz sediments and artifacts from the lower strata of Zhoukoudian Locality 1 where the remains of early members of the Peking Man family were discovered. This study marks the first radioisotopic dating of any early hominin site in China beyond the range of mass spectrometric U-series dating. The weighted mean of six meaningful measurements, 0.75 +/-; 0.09 (0.11) Ma (million years), provides the best age estimate for lower cultural Layers ^7-10^. Together with previously reported U-series^3^ and paleomagnetic^4^ data, as well as sedimentological considerations^8, 9^ these layers may be further correlated to S6-S7 in Chinese loess stratigraphy or marine isotope stages 17-18, in the range of ~0.68-0.75 Ma. These ages are substantially older than previously supposed and may imply hominin presence in northern China throughout early Middle Pleistocene climate cycles

Design and compressive behavior of controllable irregular porous scaffolds: based on Veronoi-tessellation and for additive manufacturing

Adjustment of the mechanical properties (apparent elastic modulus and compressive strength) in porous scaffolds is important for artificial implants and bone tissue engineering. In this study, a top-down design method based on Voronoi-Tessellation was proposed. This method was successful in obtaining the porous structures with specified and functionally graded porosity. The porous specimens were prepared by selective laser melting technology. Quasi-static compressive tests were conducted as well. The experiment results revealed that the mechanical properties were affected by both porosity and irregularity. The irregularity coefficient proposed in this study can achieve good accommodation and balance of “irregularity” and “controllability”. The method proposed in this study provides an efficient approach for the bionic design and topological optimization of scaffolds

Stability analysis and numerical simulation of foundation in old goaf under building load

This study comprehensively analyzes the safety and stability of old goaf under construction engineering based on specific projects using a variety of research methods. The Beijing Mentougou mining area is used as the research background. The methods of field investigation, laboratory testing, engineering drilling, geophysical exploration, theoretical calculation, and numerical simulation are combined to quantitatively analyze the stability of the foundation and ground buildings in old goaf. The influence depth of the building load and height of the caving crack zone are calculated using the “three-zone theory” to judge if the goaf is at risk of activation. Further simulation is conducted using two types of finite element analysis software, which increases the reliability of the numerical analysis. The results demonstrate that uneven subsidence of approximately 100 mm occurs in the buildings and ground surface, and subsidence of approximately 50 mm occurs in the goaf roof. It is also proven that goaf affects the stability of the surrounding rock and building foundation. Finally, a goaf treatment scheme is proposed. The treatment effect is found to be remarkable through field tests and numerical simulations, ensuring the safety and stability of a building foundation. The combination of theoretical calculation and numerical simulation can effectively evaluate the safety and stability of the project under load, and has a strong promotion and application value. The research results meet the needs of engineering practice, and provide a great reference value for the rational utilization of the land above the old goaf in the Mentougou district of Beijing and similar mining cities, which has a good theoretical significance and application prospect

Impact of intestinal microbiota on metabolic toxicity and potential detoxification of amygdalin

Amygdalin (Amy) is metabolized into cyanide in vivo, which may lead to fatal poisoning after oral administration. The defense mechanisms against toxic cyanide have not yet been adequately studied. In this study, comparative toxicokinetics study of Amy was performed in normal and pseudo germ-free rats. The efficiency of cyanide release was significant higher in normal group when given a single oral dose of 440 mg/kg (50% median lethal dose). Thiocyanate, the detoxification metabolite, was firstly detected in feces, caecum, and intestinal microbiota incubation enzymic system. The results suggest intestinal microbiota is involved in bidirectional regulation of toxicity and detoxification of Amy. We further identified the species related to cyanogenesis of Amy with metagenomic sequencing, such as Bifidobacterium pseudolongum, Marvinbryantia formatexigens, and Bacteroides fragilis. Functional analysis of microbiota reveals the detoxification potential of intestinal microbiota for cyanide. Sulfurtransferase superfamily, such as rhodanese, considered as main detoxification enzymes for cyanide, are largely found in Coriobacteriaceae bacterium, Butyricicoccus porcorum, Akkermansia muciniphila, etc. Besides, cyanoamino acid metabolism pathway dominated by Escherichia coli may contribute to the detoxification metabolism of cyanide. In summary, intestinal microbiota may be the first line of defense against the toxicity induced by Amy

Intrachromosomal Looping Is Required for Activation of Endogenous Pluripotency Genes during Reprogramming

SummaryGeneration of induced pluripotent stem cells (iPSCs) by defined factors is an extremely inefficient process, because there is a strong epigenetic block preventing cells from achieving pluripotency. Here we report that virally expressed factors bound to the promoters of their target genes to the same extent in both iPSCs and unreprogrammed cells (URCs). However, expression of endogenous pluripotentcy genes was observed only in iPSCs. Comparison of local chromatin structure of the OCT4 locus revealed that there was a cohesin-complex-mediated intrachromosomal loop that juxtaposes a downstream enhancer to the gene’s promoter, enabling activation of endogenous stemness genes. None of these long-range interactions were observed in URCs. Knockdown of the cohesin-complex gene SMC1 by RNAi abolished the intrachromosomal interaction and affected pluripotency. These findings highlight the importance of the SMC1-orchestrated intrachromosomal loop as a critical epigenetic barrier to the induction of pluripotency

Transcriptomic Analysis Comparing Tumor-Associated Neutrophils with Granulocytic Myeloid-Derived Suppressor Cells and Normal Neutrophils

The role of myeloid cells in supporting cancer growth is well established. Most work has focused on myeloid-derived suppressor cells (MDSC) that accumulate in tumor-bearing animals, but tumor-associated neutrophils (TAN) are also known to be capable of augmenting tumor growth. However, little is known about their evolution, phenotype, and relationship to naïve neutrophils (NN) and to the granulocytic fraction of MDSC (G-MDSC)

: Chronological position of modern Homo sapiens sites in China based on U-series dating

International audienceThe origin and evolution of modern Homo sapiens has been the subject of an intensive debate between exponents of two competing hypotheses, multiregional origins and “recent out of Africa”. This paper presents a synthesis of the chronological studies on seven hominid sites in China based on the U-series dating, five of them of intercalated speleothem calcites and other two of fossil materials. The results show that modern humans were present in China about 100ka ago, much earlier than previously estimated, and that the so-called “temporal gap” of human presence in China between 40 and 100ka is most probably nothing but an artifact caused by systematic errors of the dating methods. Further multidisciplinary studies on hominid sites in China may provide important evidence for resolving the hotly debated issues concerning the origin of modern humans.L'origine et l'évolution de l'Homme moderne a été le sujet d'un débat intensif entre les partisans de deux hypothèses concurrentes, le développement multirégional et l'émergence africaine unique. L'article présenté ici donne une synthèse des études chronologiques de sept sites en Chine, basées sur la datation par la méthode U-Th de formations de spéléothèmes intercalées pour cinq d'entre eux et de matériels fossiles pour les deux autres. Les résultats montrent que les Hommes modernes étaient présents en Chine il y a 100ka environ, beaucoup plus tôt que ce qui avait été estimé auparavant, et que la prétendue « lacune temporelle » de la présence de l'Homme en Chine entre 40 et 100ka n'est plus probablement qu'un artefact causé par des erreurs systématiques des méthodes de datation. Davantage d'études multidisciplinaires sur les sites à hominidés en Chine devraient fournir des évidences importantes pour la résolution des questions vivement débattues concernant l'origine des Hommes modernes

U-series dating of speleothem samples from guanyindong cave at qianxi county, Guizhou province

Guanyindong Cave, situated at Qianxi County in Guizhou Province, with an abundance of paleolithic artifacts and of fossil remains, is considered as one of the most important paleolithic sites in South China. The Ailuropoda-Stegodon fauna of Group B deposits was assumed to be formed in early Middle Pleistocene judging mainly by the existence of Tertiary survivals, and Group A deposits without Tertiary survivals in Middle Pleistocene. The biostratigraphic conclusion contradicts sharply with the results of U-series dating of fossil hones which give an age range of 57-115 ka for all the artifact and fossil containing layers. Based on the U-series dating of speleothem samples, the Group A deposits of this site should be younger than 40 ka, the 3rd layer of Group B younger than 50 ka, and 4-8 layers of Group B between 50 and 240 ka. If the stratigraphic study may prove the uniformity of Group B deposits, the age of 4-8 lavers may be further narrowed to 100-190 ka. The results of this paper do not support the biostratigraphic relative age, but confirm that the lower part of Group B belongs to a late period of Middle Pleistocene, being the latest fossil record of Gomphotheriidae. This site may represent the cultural evolution traversing the lower, middle and upper paleolithic periods in South China