Misorientations across boundary planes in a sintered NdFeB permanent magnet.

From the perspective of crystallography, there exist crystals as well as boundary planes in NdFeB permanent magnets and accordingly, there should exist orientation textures of Nd2Fe14B crystals and orientation texture of boundary planes. This work therefore aims to study the misorientations across boundary planes in a sintered NdFeB permanent magnet. As an interdisciplinary study, serial stereological methods are developed to extract more structural information from the material and as the result, spreading wetting and penetration of Nd-Rich phases to the Nd2Fe14B phase are quantificationally characterized. The entire boundaries are sorted into Nd2Fe14B/Nd2Fe14B grain boundaries (N/N boundaries) and Nd2Fe14B/(thin-layer-like)Nd-Rich phase boundaries (N/R boundaries). 31°/[0 0 1] and 60°/[0 0 1] twist boundaries are preferred among N/N boundaries, while 31°/[0 0 1] and 72°/[0 0 1] misorientations are preferred among N/R boundaries. The structural features of these misorientations are elaborated via the Five Parameter Analysis (FPA) method. The potential correlations between the grain boundary plane distributions (GBPDs) and magnetic properties are then discussed regarding how the anisotropic features at boundary locations impact coercivity, domain and remanence.

Genetic polymorphisms of 16 X-STR loci in the Hani population from Southwest China.

X chromosomal short tandem repeats (X-STRs) have the characteristics of both autosomal and uniparental genetic markers and have been shown to be particularly useful in forensic casework. However, relevant research or reports have not focused on X-STRs in the Hani population. To investigate the genetic variation and forensic efficiency of 16 X-STR loci in the Hani ethnic minority, we calculated the allele frequencies and forensic parameters of 451 (116 males and 335 females) unrelated healthy Hani individuals from Yunnan Province, Southwest China. All these loci are highly polymorphic in Hani individuals in Yunnan Province except DXS6800. The combined power of discrimination in males (PDM) and power of discrimination in females (PDF) were found to be 0.999 999 998 433 993 and 0.999 999 999 999 998, respectively. Furthermore, a population genetic structure investigation between the Yunnan Hani population and another 18 populations was performed using a principal component analysis, multidimensional scaling plot and neighbouring-joining phylogenetic tree and the findings illustrated that neighbouring populations and different nationalities in the same area appeared to have a closer evolutionary relationship. This study provides the first batch of X chromosome genetic polymorphism data of the Hani population in Yunnan Province, Southwest China and enriches the reference database of the Chinese minority population.Key pointsThis is the first study of X-STR in the Hani population.We calculated the allele frequencies and forensic parameters of 451 unrelated healthy Hani individuals from Yunnan Province, Southwest China.All these loci are highly polymorphic in Hani individuals in Yunnan Province except DXS6800.The genetic relationship between the Hani and other 18 nationalities was analyzed.This study provides the first batch of X chromosome genetic polymorphism data of the Hani population in Yunnan Province, Southwest China and enriches the reference database of the Chinese minority population.

Forensic genetic polymorphisms of 16 X-STR loci in the Yunnan Miao population and their relationship to other Chinese groups.

Allele frequencies for 16 X-chromosomal STR (X-STR) loci were obtained from a sample set of 440 unrelated Yunnan Miao individuals in China. A total of 117 alleles were observed in this group, with allele frequencies ranging from 0.0016 to 0.7565. The most informative marker for the studied population was DXS10134, with a polymorphism information content (PIC) of 0.8499, and the least polymorphic locus was DXS6810 (PIC = 0.3071). The power of discrimination (PD) varied from 0.4046 (DXS6800) to 0.8642 (DXS10134) in males and from 0.6188 (DXS6800) to 0.9673 (DXS10134) in females. The combined PDM and PDF were 0.999999989975990 and 0.999999999999949, respectively. The combined MECD and MECT were 0.999983301904059 and 0.999999915883733, respectively. Furthermore, population genetic structure investigation between the Yunnan Miao and 20 other populations using principal component analysis (PCA), multidimensional scaling plot (MDS), and neighboring-joining (NJ) phylogenetic tree analyses illustrated significant genetic difference between the Yunnan Miao and the other populations. This study is the first to provide X chromosome genetic polymorphism data of the Miao population in Yunnan Province and can be used as a supplementary reference to enrich the national database.

EBSD Investigation of the Microtexture of Weld Metal and Base Metal in Laser Welded Al⁻Li Alloys.

Autogenous laser welding of 5A90 Al⁻Li alloy sheets in a butt-joint configuration was carried out in this study. The microstructure characteristics of the weld metal and base metal in the horizontal surface and the transverse section of the welded joints were examined quantitatively using electron back scattered diffraction (EBSD) technique. The results show that the weld metal in the horizontal surface and the transverse section exhibits similar grain structural features including the grain orientations, grain shapes, and grain sizes, whereas distinct differences in the texture intensity and misorientation distributions are observed. However, the base metal in the horizontal surface and the transverse section of the joints reveals the obvious different texture characteristics in terms of the grain orientation, grain morphology, predominate texture ingredients, distribution intensities of textures, and grain boundary misorientation distribution, resulting in the diversity of the microhardness in the base metal and the softening of the weld metal. However, the degree of the drop in the hardness of the weld metal is highly correlated to the microtexture developed in the base metal.

Grain boundary plane distribution and its potential correlation with magnetic properties in hexagonal RCo5 permanent magnets.

Grain boundary plane distributions (GBPDs) are demonstrated to be spatially inhomogeneous in RCo5 permanent magnets. The potential effect of GBPDs on magnetic properties is proposed from major performance considerations, and approaches to exactly differentiate the boundary population are introduced. The crystallographic texture in permanent magnets should cover not only the texture of the crystals, but also the texture between crystals, which is helpful to advance the present understanding of the relationship between textures and properties in permanent magnets.

Characterization and analysis of the aspect ratio of carbide grains in WC-Co composites.

To study the aspect ratio distribution of carbide grains in WC-Co composites, two novel approaches, namely grain shape ellipse calculation and five parameter analysis (FPA) methods, are reported in this work. According to grain shape ellipse calculation, carbide grains that have a grain shape aspect ratio of 0.62 demarcate the more anisotropic grains with a larger size and the less anisotropic grains with a smaller size. Moreover, these grains remained predominantly populous under different cases of structural parameters and processing factors. According to five parameter analysis, the interface area aspect ratio can be derived from the relative area of prevalent (0001) basal planes and (10-10) prismatic planes, and can then be set relevance with the measured mechanical properties. The present work therefore offers new alternatives to establish the connection between the aspect ratio measurement and the property optimization of WC-Co composites.

Genetic polymorphisms of 24 Y-STR loci in Hani ethnic minority from Yunnan Province, Southwest China.

In the present study, 24 Y-chromosomal short tandem repeat (Y-STR) loci were analyzed in 250 unrelated Hani male individuals from Lvchun county, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, Southwest China. The gene diversity of the 24 Y-STR loci in the studied Hani group ranged from 0.2683 (DYS437) to 0.8837 (DYS447). According to haplotypic analysis of the 24 Y-STR loci, 204 different haplotypes were obtained, 174 of which were unique. The haplotype diversity and discrimination capacity in Hani group were 0.9977 and 0.8160 at 24 STR loci, respectively. Six single non-fraction off-ladder alleles were observed at DYS447 in 103 samples, in addition to the alleles 19 to 28 included in the allelic ladder, alleles 13, 14, 15, 16, 17, and 18 were also observed at DYS447. One intermediate allele 20.2 was observed in one individual at DYS527a/b. We analyzed interpopulation differentiations by making comparisons between Yunnan Hani group and other 17 groups. The results of pairwise genetic distances, multidimensional scaling plot, and neighbor-joining tree at the same set of 17 Y-filer loci indicated that Yunnan Hani group had the closer genetic relationships with Yunnan Han group. The present results may provide useful information for paternal lineages in forensic cases and can also increase our understanding of the genetic relationships between Hani and other groups.

Population genetic data for 17 autosomal STR markers in the Hani population from China.

The Hani is a local minority in the southwestern part of China. To establish a database of ethnic short tandem repeats (STRs), 17 autosomal STRs in the Hani ethnic group were investigated. A total of 706 unrelated individuals from three Hani settlements were genotyped using the PowerPlex 18D System. Allele frequency data and forensic parameters were evaluated. The genetic relationship among the Hani and 11 related populations was assessed.