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For the purpose of adjusting the calculation of the contact pattern of real hypoid gears, the double third-power spline surface is used for fitting tooth surfaces of pinions and gears accurately according to the measurement results of the gear surface. Based on the two-dimension golden section method for increasing the density of gear grid mesh points, the contact analysis algorithm for discrete real gear surface is established to carry out the contact information of real gear surface and adjust parameters of contact patterns, which is applied for adjusting of machining-tool settings conveniently. In the end, a hypoid gear pair of automobile driving axles is used to verify the feasibility and correctness of the proposed algorithm by rolling tests, which shows that the contact pattern by discrete tooth contact analysis is consistent with the real rolling test.

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]

Mycoplasma synoviae (MS) is an important avian pathogen that has brought substantial economic losses to the global poultry industry. Fast and accurate diagnosis is one of the critical factors for the control of MS infection. This study established a simple, rapid and visual detection method for MS using a recombinase-aided amplification (RAA) combined with a lateral flow dipstick (LFD). The reaction temperature and time of the RAA-LFD assay were optimized after selecting the primers and probe, and the specificity and sensitivity rates were analyzed. The results showed that RAA could amplify the target gene in 20 min at a constant temperature of 38°C, and the amplification products could be visualized by LFD within 5 min. There was no cross-reaction with Mycoplasma gallisepticum (MG), Pasteurella multocida ( P. multocida ), Escherichia coli ( E. coli ), Newcastle disease virus (NDV), infectious bursal disease virus (IBDV), infectious bronchitis virus (IBV), and avian reovirus (ARV). Furthermore, the RAA-LFD assay exhibited high sensitivity with a detection limit of 10 copies/μL. A total of 128 clinical samples with suspected infection of MS were tested by RAA-LFD, PCR, and real-time fluorescence quantitative PCR (RFQ-PCR). The coincidence rate of the detection results was 95.3% between RAA-LFD and PCR, and 98.4% between RAA-LFD and RFQ-PCR. These results suggested that the RAA-LFD method established in the present study was easy to use and was associated with strong specificity and high sensitivity. This method was very suitable for the rapid detection of MS in clinical practice. [ABSTRACT FROM AUTHOR]