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In this study, the response surface experiment of the turning combined with ball burnishing was carried out. The surface topography of turning and ball burnishing was observed and analyzed. The characteristics of the surface roughness profile curve corresponding to surface topography were analyzed, and the stress concentration factor of the profile curve was calculated. The distribution characteristics of residual stress in the surface layer were revealed, and a distribution model was proposed. Nondominated sorting genetic algorithm-II was used to optimize the surface residual stress and surface residual stress in the axial direction. Additionally, the microstructure under optimized burnishing parameters was observed and analyzed. The results show that only turning marks can be observed after burnishing, and the stress concentration factor decreases significantly. A spoon-shaped distributed residual compressive stress layer is formed after burnishing, and the proposed model can effectively predict the distribution of residual stress along the depth. The optimal burnishing parameters are 18 MPa, 0.05 mm/r, 600 r/min, and 2 for the burnishing force, burnishing feed, burnishing speed, and number of passes. Moreover, under the optimized parameters, the second α phase (αs) was deflected obviously, and the grains close to the surface are refined and the mean grain size is 11.31 μm. [ABSTRACT FROM AUTHOR]

The material properties of the surface layer caused by deep rolling are closely related to the degree of strain hardening. It is of great significance to establish the prediction model of strain distribution to realize the surface strain control and improve the service performance of deep rolling parts. In this study, the analytical models of elastic-plastic strain based on the Hertz contact theory were established by two different methods. The accuracy of the analytical prediction model of elastic-plastic strain was examined by deep rolling simulation. Then, the influence of deep rolling parameters, such as rolling force, the ball diameter, and material on the elastic-plastic strain along the depth was studied and validated by the microhardness profiles along the depth. The results indicate that the analytical model established by the first method is more accurate, and the error between maximum elastic-plastic strain obtained by the first method and finite element (FE) simulation is 12.6%. The elastic-plastic strain along the depth increases with the increasing rolling force and decreases with the increasing ball diameter, and its effective depth increases with the increasing rolling force. The tungsten carbide ball generates more elastic-plastic strain than balls of the other two materials (silicon nitride and steel). In addition, the elastic-plastic strain profiles are in accordance with the change of microhardness along the depth. In a word, the model can be used to predict the strain distribution along the depth induced by deep rolling. [ABSTRACT FROM AUTHOR]

To clarify the effects of deep rolling parameters on residual stress, two-dimensional and three-dimensional finite element models were developed using the Chaboche hardening model. Both two-dimensional and three-dimensional simulation results were compared with experimental results. The three-dimensional model is more accurate, especially the 90° cut-out model. The maximum errors in the longitudinal and circumferential directions of 90° cut-out are 8.9% and 15.6%, respectively. Compared to 20 MPa, a rolling pressure of 38 MPa results in larger and deeper compressive residual stress in both directions, but lower surface residual stress in the circumferential direction. Compared to 30% overlap, 60% overlap produces larger compressive residual stress in the near surface region in the longitudinal direction and deeper residual stress with lower maximum compressive residual stress in the circumferential direction. The friction coefficient only slightly affects residual stress in the circumferential direction; increasing the rolling speed induces higher near surface residual stress in the circumferential direction. Compared to the HG6 tool, the HG8 tool generates decreasing surface residual stresses and deeper residual stress in both directions. Compared to one pass, two passes significantly increase the residual stress in circumferential direction, but only slightly increase the residual stress in the longitudinal direction. [ABSTRACT FROM AUTHOR]

Long noncoding RNAs (lncRNAs) regulate metabolic tissue development and function, including adipogenesis. However, little is known about the function and profile of lncRNAs in intramuscular preadipocyte differentiation in chicken. Here, we identified lncRNAs in chicken intramuscular preadipocytes at different differentiation stages using RNA sequencing. A total of 1,311,382,604 clean reads and 25,435 lncRNAs were obtained from 12 samples. In total, 7,433 differentially expressed genes (4,698 lncRNAs and 2,735 mRNAs) were identified by pairwise comparison. These 7,433 differentially expressed genes were grouped into 11 clusters based on their expression patterns by K-means clustering. Using Weighted Gene Coexpression Network Analysis, we identified four stage-specific modules positively related to I0, I2, I4, and I6 stages and two stage-specific modules negatively related to I0 and I2 stages, respectively. Many well-known and novel pathways associated with intramuscular preadipocyte differentiation were identified. We also identified hub genes in each stage-specific module and visualized them in Cytoscape. Our analysis revealed many highly-connected genes, including XLOC_058593, BMP3, MYOD1, and LAMP3. This study provides a valuable resource for chicken lncRNA study and improves our understanding of the biology of preadipocyte differentiation in chicken. [ABSTRACT FROM AUTHOR]

Newcastle disease (ND) and avian infectious bronchitis (IB) are contagious diseases of chickens. To identify genes associated with antibody levels against ND and IB, a genome-wide association study was performed using specific-locus amplified fragment sequencing (SLAF-seq) technology in Jinghai yellow chickens. This determined six single-nucleotide polymorphisms (SNPs) that were associated with antibody levels against Newcastle disease virus (NDV): rsZ2494661, rsZ2494710, rs1211307701, rs1211307711, rs1218289310 and rs420701988. Of these, rsZ2494661 and rsZ2494710 reached the 5 % Bonferroni genome-wide significance level (5.5E-07) and they were both 134.7 kb downstream of the SETBP1 gene. The remaining four SNPs had 'suggestive' genome-wide significance levels (1.1E-05) and they were within or near the Plexin B1, LRRN1 and PDGFC genes. IB had two SNPs associated with antibody levels: rs149988433 and rs16170823; both reached chromosome-wide significance levels and they were near the USP7 and TRIM27 genes, respectively. Bioinformatics, GO annotation and pathway analysis indicated that five of these genes ( Plexin B1, TRIM27, PDGFC, SETBP1 and USP7) may be important for the generation of protective antibodies against NDV and infectious bronchitis virus (IBV). This paves the way for further research on host immune responses against NDV. [ABSTRACT FROM AUTHOR]

The objective of this study was to analyze possible associations between single nucleotide polymorphisms (SNPs) in the Myf5 gene with chicken growth and reproductive traits. SNPs in Myf5 of the Jinghai yellow chicken were detected by the polymerase chain reaction single-strand conformation polymorphism method and the haplotypes were analyzed. Eight SNPs were identified in the exons of Myf5. Nine haplotypes were established in a group of 379 Jinghai yellow chickens. In terms of growth traits, least square analysis showed that haplotype H1H5 had significant effects on weight at weeks 8 and 12 ( P < 0.05). Haplotype H2H6 had significant effects on weight at weeks 12 and 14 ( P < 0.05). For reproductive traits, H1H5 had higher body weight for the first egg than H1H4 and H2H4 ( P < 0.05), and H1H3 ( P < 0.01). H1H3 had a poor performance in average egg weight at 300 days. On the other hand, H1H3 had an advantage in egg number at 300 days. The results showed that SNPs of Myf5 have certain effects on growth and reproductive traits in Jinghai yellow chickens, which can be used in marker-assisted selection to accelerate chicken genetic progress. [ABSTRACT FROM AUTHOR]