Calculation of Volume Fractions of In Situ TiB and Residual Stress Distributions in Functionally Graded Composite of Ti–TiB–TiB2

Ti matrix composite with a polylaminate structure was successfully fabricated via spark plasma sintering (SPS) process. A temperature gradient field (TGF) was obtained during the sintering to form functionally graded material (FGM) in a vacuum under 40 MPa for 5 min. The actual volume fractions of TiB in the matrix were calculated based on the X-ray diffraction pattern. The target volume fractions of TiB were 0%, 20%, 40%, 60%, 80% and 100%. The calculated TiB volume fractions were slightly higher than the target volume fractions in layers 2–4 and lower than the target volume fractions in layers 5–6 and the deviations in layers 4 and 5 were less than 5% of the target volume. Based on the elastic axial symmetry model, the residual stress distributions in the Ti matrix composite with a polylaminate structure were simulated, indicating a relatively low thermal residual stress in the FGM

Genomic insight into the population admixture history of Tungusic-speaking Manchu people in Northeast China

Manchu is the third-largest ethnic minority in China and has the largest population size among the Tungusic-speaking groups. However, the genetic origin and admixture history of the Manchu people are far from clear due to the sparse sampling and a limited number of markers genotyped. Here, we provided the first batch of genome-wide data of genotyping approximate 700,000 single-nucleotide polymorphisms (SNPs) in 93 Manchu individuals collected from northeast China. We merged the newly generated data with data of publicly available modern and ancient East Asians to comprehensively characterize the genetic diversity and fine-scale population structure, as well as explore the genetic origin and admixture history of northern Chinese Manchus. We applied both descriptive methods of ADMIXTURE, fineSTRUCTURE, F ST , TreeMix, identity by decedent (IBD), principal component analysis (PCA), and qualitative f-statistics (f 3, f 4, qpAdm, and qpWave). We found that Liaoning Manchus have a close genetic relationship and significant admixture signal with northern Han Chinese, which is in line with the cluster patterns in the haplotype-based results. Additionally, the qpAdm-based admixture models showed that modern Manchu people were formed as major ancestry related to Yellow River farmers and minor ancestry linked to ancient populations from Amur River Bain, or others. In summary, the northeastern Chinese Manchu people in Liaoning were an exception to the coherent genetic structure of Tungusic-speaking populations, probably due to the large-scale population migrations and genetic admixtures in the past few hundred years.Published versionThis study was supported by grants from the National Natural Science Foundation of China (No. 31571233), the scientific research project from the Education Department of Liaoning Province (No. JYTJCZR2020074), the Nanqiang Outstanding Young Talents Program of Xiamen University (X2123302), the Fundamental Research Funds for the Central Universities (ZK1144), the Major Project of the National Social Science Foundation of China (20&ZD248), and European Research Council (ERC) grant (ERC-2019-ADG-883700-TRAM)

Low Light Stress Increases Chalkiness by Disturbing Starch Synthesis and Grain Filling of Rice

Low light stress increases the chalkiness of rice; however, this effect has not been fully characterized. In this study, we demonstrated that low light resulted in markedly decreased activity of ADP-glucose pyrophosphorylase in the grains and those of sucrose synthase and soluble starch synthase in the early period of grain filling. Furthermore, low light also resulted in decreased activities of granule-bound starch synthase and starch branching enzyme in the late period of grain filling. Therefore, the maximum and mean grain filling rates were reduced but the time to reach the maximum grain filling rates and effective grain filling period were increased by low light. Thus, it significantly decreased the grain weight at the maximum grain filling rate and grain weight and retarded the endosperm growth and development, leading to a loose arrangement of the amyloplasts and an increase in the chalkiness of the rice grains. Compared to the grains at the top panicle part, low light led to a greater decrease in the grain weight at the maximum grain filling rate and time to reach the grain weight at the maximum grain filling rate at the bottom panicle part, which contributed to an increase in chalkiness by increasing the rates of different chalky types at the bottom panicle part. In conclusion, low light disturbed starch synthesis in grains, thereby impeding the grain filling progress and increasing chalkiness, particularly for grains at the bottom panicle part