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Short tandem repeats (STRs) located on the Y chromosome with the properties of male-specific inheritance and haploidy are widely used in forensics to analyze paternal genealogies and match male trace donors to evidence. Besides, Y-chromosomal haplotypes play an important role in providing breathtaking insights into population genetic history. However, the genetic diversity and forensic characteristics of Y-STRs in Guizhou main ethnic groups (Hans, Miaos and Bouyeis) remain uncharacterized. Here, we obtained Y-chromosomal 23-marker haplotypes in three Guizhou populations and submitted the first batch of Y-STR haplotype data to the YHRD. The HD in the aforementioned three populations are 0.99990, 0.99983, and 0.99979, respectively, and DC values are 0.9902, 0.9908, and 0.97959, respectively. Subsequently, genetic differentiation between our newly studied populations and reference groups along ethnic/administrative divisions, as well as national/continental boundaries were investigated via AMOVA, MDS, and phylogenetic relationship reconstruction. Significant genetic differentiations from our subjects and other groups are identified in ethnically, linguistically and geographically diverse populations, including most prominently Tibetans and Uyghurs among 30 mainland Chinese populations, Taiwanese groups and others among 58 Asian populations, as well as African groups and others among 89 worldwide populations. Qiannan Bouyei has a close genetic relationship with Guangxi Zhuang, and Zunyi Han and Qiandongnan Miao have close genetic affinity with Hunan Han and Guizhou Shui, respectively. Collectively, this new-generation Y-STR amplification system can be used as a supplementary tool in forensic identification and male parentage testing and even pedigree search.

For precision mechanical systems, different distribution characteristics of geometric form errors usually lead to different assembly contact states, and in turn, different assembly errors are formed, due to the propagation and accumulation of geometric form errors. Statistically, a batch of part machined by the same precision process possesses the identical distribution characteristics of geometric form errors. It is of great importance to improve assembly accuracy and productivity if the statistic distribution characteristics of geometric form errors can be understood. To solve the problem, two methods of modeling geometric form errors for single parts based on linear combination of basis shapes and modeling statistic geometric form errors for a batch of parts machined by the same process on the basis of principal component analysis are proposed in this article. Besides that, evaluating indicators of model accuracy are also proposed. The results of the case study imply that the two methods can model geometric form errors of single parts and statistically model geometric form errors of a batch of parts, effectively and reliably.

In order to improve the spinnability and develop a potential application of konjac glucomannan (KGM), KGM grafted with styrene (St)/butyl acrylate (BA) (KGM-g-St/BA) was prepared via free-radical polymerization in this study. Subsequently, fibers of KGM-g-St/BA and core/shell poly(caprolactone) (PCL)/KGM-g-St/BA fibers were respectively obtained by electrospinning technique. The properties of KGM-g-St/BA copolymer and fibers were characterized by FTIR, TG, SEM, FE-SEM and TEM. The hydrophobic property of KGM dramatically increased after grafting modification. KGM-g-St/BA graft copolymer fiber film and core/shell fiber film have a good hydrophobic property.

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