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OBJECTIVE: The purpose of this study was to investigate role of inhibition of microRNA- 34a (miR-34a) in neural damage and repair after spinal cord injury, and to explore the underlying mechanism. MATERIALS AND METHODS: In BV2 microglia, we conducted classical activation using lipopolysaccharide (LPS) and pre-treatment using miR-34a mimics. The expressions of miR-34a, Notch 1, and Jagged 1 were detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). Moreover, the protein expressions of inflammatory microglia markers were evaluated by Western blotting. In vivo, SCI model was successfully established in rats. Subsequently, the expression levels of miR-34a, Notch 1, and Jagged 1 levels within 1 week were measured by qRT-PCR. Meanwhile, protein expressions of inflammatory mediators were determined by enzyme- linked immunosorbent assay (ELISA) assay. Immunofluorescence was conducted to display the activation degree of microglia and residual neural structure. Furthermore, locomotor function recovery was estimated using BBB rating scale. RESULTS: Compared with the only LPS-activated group, pre-treatment of miR-34a mimics significantly decreased the expressions of Notch 1 and Jagged 1. Similarly, the protein expressions of CD11b and iNOS were significantly down-regulated. In vivo, the levels of Notch 1 and Jagged 1 within 1 week increased significantly, while miR-34a was negatively regulated following spinal cord injury (SCI). Furthermore, the contents of interleukin-1 beta (IL-1ß) and IL- 6 were reduced with the treatment of miR-34a mimics when compared with SCI group. With the treatment of miR-34a, the number of inflammatory microglia decreased significantly, and the remaining neural structure was similarly improved. In addition, locomotor function recovery of hindlimbs in rats was significantly ameliorated after the administration of miR-34a mimics. CONCLUSIONS: Increase of miR-34a suppresses neuronal apoptosis and alleviates microglia inflammation by negatively targeting the Notch pathway, thereby improving neural recovery and locomotor function. [ABSTRACT FROM AUTHOR]

In order to improve the lifespan of electrodes used for spot-welding galvanised steel plates, electrodes coated with TiB2-TiC composite were studied. Scanning electron microscope and X-ray diffraction were employed to analyse the failure process of TiB2-TiC composite-coated electrodes when they were used for spot-welding galvanised steel plates. The analysis results show that the influence of mechanical force and welding heat, along with other factors, could lead to the generation of cracks in the originally complete TiB2-TiC composite coating. The developed cracks weave into a mesh, which enhances the extent of alloying between the TiB2-TiC composite-coated electrode and the zinc coating of the galvanised steel plate. Because of the influence of local alloying, the coatings tend to peel off in pieces, resulting in a higher level of alloying and the final failure of TiB2-TiC composite-coated electrodes. Failure of TiB2-TiC composite-coated electrodes is the result of both alloying and plastic deformation. [ABSTRACT FROM AUTHOR]

Single tracks of selective laser melted FeAl intermetallics were studied in this paper in order to manufacture a perfect part. The morphology evolution of single tracks with the variation in laser scanning speed was analysed, and the bottom heating of substrate or premelted layer was proposed to obtain a better flattening degree of molten FeAl droplets. Reasonable mechanisms for morphology evolution were provided. It is revealed that with increasing the laser scanning speed, the surface tension gradient plays an important role in morphology evolution, while the bottom heating of substrate or premelted layer can counteract the contraction effect of FeAl particles induced by laser scanning speed. [ABSTRACT FROM AUTHOR]