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The TiC/Ni composites with different CeO2 or CeO2@Ni content are fabricated by pressureless reactive sintering, and the CeO2@Ni particles are prepared by electroless plating technique. The results show that the continuous Ni layer is prepared on CeO2 particles, leading to the decrease of contact angle between CeO2 and Ni from about 116° to 65°. The relative density of composites with 1 wt% CeO2 increases from 85.79% to 96.45% by Ni layer on CeO2 particles. The CeO2 or CeO2@Ni particles exhibit no obvious influence on the microstructure of composites, and Ce atoms of CeO2 diffuse into TiC particles during the reactive sintering process. The mass gain of composite decreases from 7.4709 to 4.9075 mg cm−2 by addition of 1 wt% CeO2@Ni. The Ce‐doped in NiO and TiO2 would restrict the inward diffusion of O atoms and outward diffusion of Ni atoms, resulting in the improvement of oxidation resistance of composite. With the increase of CeO2@Ni content from 0 to 1 wt%, the surface specific resistance of composite decreases from 3.16 to 0.56 Ω cm2 at 800 °C due to the thinner oxide scale and lower bandgap of TiO2 by Ce doping. [ABSTRACT FROM AUTHOR]

Background: Oral submucous fibrosis (OSF) is associated with malignant disorders. DNA methyltransferase 3A (DNMT3A) is a DNA methylesterase reported to be upregulated in multiple organs and shown to inhibit fibrosis. However, the detailed effect of DNMT3A on OSF remains unclear. Methods: To mimic OSF in vitro, oral fibroblasts were exposed to arecoline and molecular biological experiments were performed to detect the function of DNMT3A in OSF. Results: We found that von Hippel–Lindau (VHL) was downregulated and highly methylated in OSF. Arecoline remarkably increased the viability, invasiveness, and migration of oral fibroblasts, but upregulation of VHL partially reversed these effects. DNMT3A induces DNA hypermethylation in the VHL promoter, and VHL markedly inhibits the level of tenascin‐C (TNC) by inducing the ubiquitination of TNC. TNC reversed the inhibitory effect of VHL upregulation on the differentiation of oral fibroblasts into myofibroblasts. Conclusion: DNMT3A induces OSF by promoting methylation of the VHL promoter. Hence, our study provides novel insights into the discovery of novel strategies that can be employed against OSF. [ABSTRACT FROM AUTHOR]

In seismic tomography practices the Earth's surface is sometimes assumed to be either spherical or flat for convenience in forward modelling calculations. The effect of irregular surface topography on seismic wave propagation is thus ignored, resulting in biases in the phases and amplitudes of synthetic seismograms, which contribute to the residuals that are mapped into velocity structures in tomography inversions. In this study, we conduct a series of inversion experiments based on the adjoint waveform tomography method to quantitatively assess the topography effect on waveform-based inversion results. We first employ models with simplified topography to better highlight and quantify the topography effect. Results show that when topography effect is ignored in the forward modelling, it is mapped into velocity perturbations, leading to spurious velocity anomalies in tomography models. The strength of the spurious velocity anomaly is quasi-linearly related to locally averaged topography gradient. Our inversion experiments demonstrate that in places of strong topography variation, such as the Longmenshan Fault Zone region where the 2008 M w 7.9 Wenchuan earthquake occurred, topography effect can lead to spurious relative velocity anomalies of up to 10 per cent, which cannot be ignored in waveform-based tomography inversions. [ABSTRACT FROM AUTHOR]

The short-distance coal seam group refers to the coal seams which has obvious mining influence on the adjacent coal seam during mining process. In the process of short-distance coal seam mining, there are a large number of cracks around the stope due to the mining stress, resulting in serious air leakage and high risk of spontaneous combustion. To mining the working face under the condition of overlying close goaf in Xutuan Coal Mine in Huaibei Mining area, the distribution of spontaneous combustion dangerous area in goaf was studied systematically with the help of engineering test, laboratory research and numerical simulation. Results show that a "Γ" distribution of high oxygen concentration area was found above the roadway of the goaf due to the effect of air leakage and coal seam space, the high spontaneous combustion risk area is close to the return airway. A three-dimensional distribution of the high spontaneous combustion risk area was formed in the composite goaf after mining in the lower coal seam face, the spontaneous combustion risk of the upper position is higher than that of the lower position. Besides, based on the pyrolysis-room temperature oxidation experiments of coal sample, it is considered that the inert environment and high temperature promote the production of active groups in coal and thus enhanced the oxidation ability of coal, mechanism of spontaneous combustion of residual coal in the overlying goaf was further revealed. Accordingly, the comprehensive fire prevention and fire extinguishing measures of nitrogen injection, leakage plugging and inhibitor injection are put forward. With the method of numerical simulation, it was found that nitrogen injection at the position of 50 m in the goaf can effectively reduce the spontaneous combustion risk in the compound goaf, and the injection of TEMPO inhibitor was put forward based on the secondary oxidation characteristics of residual coal. The research conclusion can provide theoretical guidance for the fire prevention technology of coal seam mining in the overlying close goaf. [ABSTRACT FROM AUTHOR]