Transplantation of vasculogenic progenitor cells (VPC) improves neovascularization after ischemia. However, patients with type 2 diabetes mellitus show a reduced VPC number and impaired functional activity. Previously, we demonstrated that p38 kinase inhibition prevents the negative effects of glucose on VPC number by increasing proliferation and differentiation towards the endothelial lineage in vitro. Moreover, the functional capacity of progenitor cells is reduced in a mouse model of metabolic syndrome including type 2 diabetes (Lepr^db) in vivo. The aim of this study was to elucidate the underlying signalling mechanisms in vitro and in vivo. Therefore, we performed DNA-protein binding arrays in the bone marrow of mice with metabolic syndrome, in blood-derived progenitor cells of diabetic patients as well as in VPC ex vivo treated with high levels of glucose. The transcriptional activation of ETS transcription factors was increased in all samples analyzed. Downregulation of ETS1 expression by siRNA abrogated the reduction of VPC number induced by high-glucose treatment. In addition, we observed a concomitant suppression of the non-endothelial ETS-target genes matrix metalloproteinase 9 (MMP9) and CD115 upon short term lentiviral delivery of ETS-specific shRNAs. Long term inhibition of ETS expression by lentiviral infection increased the number of cells with the endothelial markers CD144 and CD105. These data demonstrate that diabetes leads to dysregulated activation of ETS, which blocks the functional activity of progenitor cells and their commitment towards the endothelial cell lineage.

The tribological performance of the friction pair between the rotor and finger feet is a crucial index affecting the service life of finger seals. In recent years, the surface texture has attracted a considerable number of researchers owing to its extraordinary potential in improving antifriction and wear resistance. This paper, inspired by snakeskins, introduces three texture forms (e.g., diamond, ellipse, and hexagon) into the rotor. The effects on finger-sealing performance are analyzed by considering finger seals’ varied working conditions. First, a numerical model of textured finger seals under hydrodynamic lubrication is established based on the Reynolds equation. Then, the sealing performance analysis of textured finger seals is performed considering varied working conditions given rotation speed, pressure difference, seal clearance, and working temperature. The numerical results show that: (1) the textured domain produces a noticeable hydrodynamic pressure effect and cavitation, which effectively improves the bearing capacity of the fluid film; (2) the higher the rotation speed or the lower the inlet/outlet pressure difference, the stronger the dynamic pressure effect of textured finger seals and the better the antifriction and wear resistance; (3) for good antifriction and wear resistance of a textured finger seal, the seal clearance should be as shallow as possible (≤10 μm), and the working temperature should be as low as possible (≤120 °C); and (4) the ellipse texture has a higher average dimensionless pressure and a lower friction coefficient, which is superior to diamond and hexagon ones in terms of friction and wear performance.

In recent years, surface textures have been found with extraordinary potential to improve lubrication of friction pairs, reduce viscosity, and improve wear resistance. To study the effects of surface textures in the finger sealing, as inspired by the snakeskin, four texture forms with different layouts are presented in this paper and comprehensive performance analysis is carried out under the condition of hydrodynamic lubrication. First, a numerical model of finger seals with surface textures under hydrodynamic lubrication is proposed based on the Reynolds equation. Then, finger seal performance analysis is carried out considering different texture surfaces in terms of forms, layouts, and geometric parameters. The results show that: (1) When the texture profile is consistent with the direction of rotor motion, it is beneficial to create better hydrodynamic pressure and improve sealing performance; (2) To achieve good friction and wear resistance of a textured finger seal, the texture depth should be as shallow as possible (<25 μ m); (3) When the texture depth is equal to the seal clearance, the average dimensionless pressure reaches the greatest with smallest friction coefficient; (4) With the increase of the texture density, the average dimensionless pressure increases rapidly first and then gradually flattens, while the friction coefficient performs oppositely. Given the manufacturing economy, the suitable texture density is around 20% ∼ 40%.

The extraction of impulsive signatures from a vibration signal is vital for fault diagnosis of rolling element bearings, which are always whelmed by noise, especially in the early stage of defect development. Aiming at the weak defect diagnosis, kurtosis of Teager energy operator (KTEO) spectrum is employed to indicate the fault information capacity of a spectrum, and considering the accumulative effect of a singular component, accumulative kurtosis of TEO (AKTEO) is firstly proposed to determine the proper signal reconstructed order during vibration signal processing using singular value decomposition (SVD). Then, a vibration processing scheme named SVD‐AKTEO is designed where an iteration is employed to reflect an accumulative singular effect by kurtosis of TEO spectrum. Finally, the fault diagnosis results can be extracted from the TEO spectrum output by SVD‐AKTEO. Simulation data and real data from a run‐to‐failure experiment of a rolling bearing are adopted to validate the efficiency, and comparative analysis demonstrates the feasibility to detect the early defect of the rolling bearing.

Since the last decade, the non-contact finger seal (NCFS) has attracted an increasing number of researchers due to its inherent flexibility and non-contact features, which can significantly improve the service life and reduce the leakage rate of the finger seals. In this paper, to enhance the NCFS sealing performance, lifting pads with twenty (20) different herringbone groove surface topographies are proposed based on the uniform design method. Numerical analysis is carried out based on the two-way fluid-structure interaction (FSI) method to better mimic the actual working conditions. The analysis of results using statistical tools reveals that the herringbone groove topographies placed on the bottom surface of low-pressure lifting pads can significantly improve the load-carrying capacity and sealing performance. In addition, the correlation analysis of the sealing performance and geometric parameters of the herringbone groove demonstrate that reducing the groove width or increasing the groove internal angle can improve the lifting and leakage capacities. Finally, the optimal herringbone groove and general structure (no groove) are comparatively analysed under variable working conditions, and the results show that the former has much better sealing performance.