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Aim: This study aimed to evaluate the miR-223-5p expression in patients with spinal cord injury (SCI) and to determine its role in the pathogenesis of SCI. Methods: The serum miR-223-5p levels were analyzed using quantitative real-time polymerase chain reaction. The diagnostic accuracy of miR-223-5p was evaluated using the receiving operating characteristic curves. LPS-induced PC12 cells were established as an in vitro inflammatory cell model. Cell apoptosis, inflammation and oxidative stress were examined. The SCI rat model was constructed to evaluate the effects of miR-223-5p on inflammatory response and motor function in rats. Results: MiR-223-5p expression was upregulated in SCI patients. MiR-223-5p expression in the complete SCI group was significantly higher than that in incomplete SCI group. ROC analysis showed that miR-223-5p can distinguish SCI patients from healthy volunteers. In vitro experiments demonstrated that LPS upregulated apoptosis and inflammation in PC12 cells. Treatment with miR-223-5p inhibitor alleviated the changes in LPS-induced PC12 cells. Inhibition of miR-223-5p can alleviate the activation of inflammatory response and the effects of SCI on the motor function in rats. Conclusions: MiR-223-5p is a potential diagnostic marker for SCI, and it can promote the SCI progression by regulating nerve cell survival, inflammation, and oxidative stress. [ABSTRACT FROM AUTHOR]

For fiber-reinforced composites, the anisotropy and the tension-compression asymmetry have very important influence on fatigue performance. The quasi-static and fatigue mechanical behavior of plain weave laminates of carbon/polymer composites were experimentally investigated in this paper. The quasi-static and stress-controlled fatigue tests were carried out on the servo-hydraulic material testing machine. Fracture failure surfaces were observed in micro-mechanism with scanning electron microscopy. A phenomenological and nonlinear constant life diagram (CLD) model was developed based on quasi-static strength andS–Ncurve data-sets of different stress ratios. The relationship between six parameters of the proposed model and the failure cycles was studied. The fatigue experimental results showed that the fatigue failure type changed from tensile mode to compressive mode at nearby stress ratioR = −0.2. A satisfactory agreement between the predicted value of cycle life and experimental data was observed. The results indicated that the fatigue performance was adequately described by the BasquinS–Nformulation and proposed CLD. [ABSTRACT FROM PUBLISHER]

Woven composite has been increasingly employed in engineering applications undergoing complex loading conditions. For effective use of composite materials, it is essential to fully understand the mechanical behaviour of composite at different strain rates. In the present study, both in-plane tensile and compressive mechanical properties of a carbon/glass hybrid plain weave composite were experimentally investigated over the strain rate range from 0.001 to 1000 s−1. High strain rate tests were carried out using Split Hopkinson Pressure and Split Tensile Bar apparatuses, respectively. Experiments were performed at the axial direction of 0° and 90°, and the off-axial direction of 45° considering the tension/compression asymmetry and anisotropy characteristic. The results indicated that the in-plane mechanical performance was strain rate sensitive under both tensile and compressive loadings. Highly direction-dependent and tension/compression asymmetric characteristic was observed under quasi-static and high strain rate loadings. The elastic modulus showed no strain rate sensitivity for the 0° axial tension. However, for other loading conditions, the elastic modulus was enhanced by 1.7–7.2 times under high strain rate loading. The strength was increased by 1.2–2.5 times at 1000 s−1compared with that under quasi-static loading for different loading directions. For higher strain rate sensitivity under compression than tension, the asymmetry was less obvious with the increase of strain rate. Two phenomenological models were proposed to quantitatively fit the relationship between the strength property and strain rate, which showed great consistency between the experimental and fitted results. [ABSTRACT FROM AUTHOR]