RESUMEN

In the absence of externally applied mechanical loading, it would seem counterintuitive that a solid particle sitting on the surface of another solid could not only sink into the latter, but also continue its rigid-body motion towards the interior, reaching a depth as distant as thousands of times the particle diameter. Here, we demonstrate such a case using in situ microscopic as well as bulk experiments, in which diamond nanoparticles ~100 nm in size move into iron up to millimeter depth, at a temperature about half of the melting point of iron. Each diamond nanoparticle is nudged as a whole, in a displacive motion towards the iron interior, due to a local stress induced by the accumulation of iron atoms diffusing around the particle via a short and easy interfacial channel. Our discovery underscores an unusual mass transport mode in solids, in addition to the familiar diffusion of individual atoms.

RESUMEN

OBJECTIVE: SLC7A11 plays a crucial role in ferroptosis and is upregulated in oral squamous cell carcinoma (OSCC) samples. This study mainly aimed to elucidate the association of SLC7A11 with ferroptosis in OSCC and analyze its upstream regulatory mechanism. DESIGN: The expression of SLC7A11 in OSCC and paracancerous tissues was detected. After administration of different concentrations of erastin to OSCC cells, cell viability was examined by MTT, and changes in GSH, MDA and Fe2+ concentrations were determined. Then, mitochondrial changes were examined by transmission electron microscopy. Bioinformatics analysis was performed to predict the upstream regulatory miRNA of SLC7A11, and the interaction between miR-26a and SLC7A11 was confirmed by a dual luciferase reporter gene. The effect of miR-26a mimics on ferroptosis resistance was also examined. RESULTS: SLC7A11 expression was upregulated in both OSCC patients and cells, with high SLC7A11 expression levels in SCC-9 cells with an IC50 = 69.75 µM for erastin and low SLC7A11 expression levels in SCC-4 cells with an IC50 = 8.463 µM for erastin. SCC-9 exhibited a higher level of ferroptosis resistance than SCC-4. miR-26a-5p expression was downregulated in both OSCC patients and cells. A dual luciferase reporter assay confirmed that miR-26a-5p targets binding to the SLC7A11 3'UTR. Transfection of the miR-26a mimic significantly inhibited the viability of OSCC cells and promoted erastin-induced cellular ferroptosis. Transfection of miR-26a inhibitor gave the opposite result. Overexpression of SLC7A11 significantly reversed miR-26a mimic ferroptosis induction. CONCLUSION: miR-26a-5p can exert OSCC inhibitory effects by regulating SLC7A11 and promote ferroptosis in OSCC cells by inhibiting SLC7A11.

Asunto(s)

Carcinoma de Células Escamosas , Ferroptosis , Neoplasias de Cabeza y Cuello , MicroARNs , Neoplasias de la Boca , Humanos , Carcinoma de Células Escamosas/patología , Carcinoma de Células Escamosas de Cabeza y Cuello , Neoplasias de la Boca/patología , MicroARNs/genética , MicroARNs/metabolismo , Línea Celular Tumoral , Luciferasas/metabolismo , Proliferación Celular/genética , Sistema de Transporte de Aminoácidos y+/genética

RESUMEN

In situ bending tests of amorphous Si nanowires (a-Si NWs) found different elastic behavior depending on whether they were straight or curved to begin with. The axially straight NWs exhibit pure elastic deformation; however, the axially curved NWs exhibit obvious anelastic behavior when they are bent in the direction of original curvature. On the basis of STEM-EELS analysis, we propose that the underlying mechanism for this anelastic behavior is a bond-switching assisted redistribution of the nonuniform density (structure) in the curved NWs under the inhomogeneous stress field. This mechanism was further supported by the fact that the originally straight a-Si NWs also display similar anelasticity with the as-grown curved NWs after focused ion beam irradiation that can cause nonuniform structure distribution. As compared to what has been reported in other 1D materials, the anelasticity of a-Si NWs can be tuned by modifying their morphology, controlling the loading direction, or irradiating them via ion beam. Our findings suggest that a-Si NWs could be a promising material in the nanoscale damping systems, especially the semiconductor nanodevices.