The mixed linear model has been widely used in genome-wide association studies (GWAS), but its application to multi-locus GWAS analysis has not been explored and assessed. Here, we implemented a fast multi-locus random-SNP-effect EMMA (FASTmrEMMA) model for GWAS. The model is built on random single nucleotide polymorphism (SNP) effects and a new algorithm. This algorithm whitens the covariance matrix of the polygenic matrix K and environmental noise, and specifies the number of nonzero eigenvalues as one. The model first chooses all putative quantitative trait nucleotides (QTNs) with ≤ 0.005 P-values and then includes them in a multi-locus model for true QTN detection. Owing to the multi-locus feature, the Bonferroni correction is replaced by a less stringent selection criterion. Results from analyses of both simulated and real data showed that FASTmrEMMA is more powerful in QTN detection and model fit, has less bias in QTN effect estimation and requires a less running time than existing single- and multi-locus methods, such as empirical Bayes, settlement of mixed linear model under progressively exclusive relationship (SUPER), efficient mixed model association (EMMA), compressed MLM (CMLM) and enriched CMLM (ECMLM). FASTmrEMMA provides an alternative for multi-locus GWAS.

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The POB/PTFE composites were prepared by blending-cold pressing-sintering-hot pressing method. Influence of POB content on mechanical and tribological properties of the composites was investigated. Worn surfaces were analyzed by scanning electron microscope (SEM). The results indicated that ball indentation hardness and compressive strength of POB/PTFE increase with increasing POB content in composites. Tensile strength, elongation and impact strength of POB/PTFE decrease with increasing POB content in composites. Friction coefficient of composites increases compared to PTFE. Wear resistance of POB/PTFE composites was improved with filling POB. The POB/PTFE composite incorporating 20% POB has best comprehensive mechanical properties. Wear mechanism of PTFE are abrasive wear. Wear mechanism of POB/PTFE composites mainly are fatigue wear and flaking.