RÉSUMÉ
Objective To investigate the effects of high-risk human papillomavirus 16 E6 protein(HPV16 E6 protein)on invasion and migration of cervical cancer SiHa cells via regulating the expression of expression miR-23a.Methods Tissue samples from 100 patients with cervical cancer HPV-negative,100 HPV-positive patients,and 100 paracancerous normal tissues were collected;cervical cancer SiHa cells were divided into blank group,E6 overexpression group,negative transfection group,and E6 + miR-23a mimics group.The expression of miR-23a and HPV16 E6 mRNA were detected by qRT-PCR;MTT assay was used to detect the cell proliferation inhibition rate;flow cytometry to detect the apoptosis;Transwell chamber assay to detect cell invasion,and scratch test to detect the ability of cell migration.The expression of HPV16 E6,apoptosis related proteins(Caspase-3,Bax,Bcl-2),and migration related proteins(MMP-2,MMP-9)was detected by WB.Results The expression level of miR-23a was decreased in cervical cancer tissues,and that was lower in HPV positive cervical cancer tissues.Overexpression of E6 decreased the expression level of miR-23a,cell proliferation inhibition rate,apoptosis rate,Caspase-3 and Bax protein expression,and increased the expression of Bcl-2 protein,scratch healing rate,inva-sion cell number,MMP-2,MMP-9 protein expression(P<0.05);miR-23a mimics reversed the effects of E6 overexpression on the above indicators.Conclusion HPV16 E6 promotes the invasion and migration of cervical cancer cells,which may be related to the regulation of miR-23a expression.
RÉSUMÉ
A cold sprayed Al coating on S355 structural steel was processed using a laser remelting (LR). The surface and cross-section morphologies, chemical compositions, and phases of as-obtained Al coating before and after LR were analyzed using a scanning electronic microscope (SEM), energy dispersive spectrometer (EDS), and X-ray diffractometer (XRD), respectively, and their hardness was measured using a micro-hardness tester. The friction-wear behaviors of Al coating before and after LR in 3.5% NaCl solution were conducted to simulate the sand and gravel scouring on its surface in seawater, the effects of wear loads and speeds on the tribological properties of Al coating were analyzed, and the wear mechanisms under different wear loads and speeds were also discussed. The results show that the Al coating after LR is primarily composed of an Al phase and its hardness is 104.66 HV, increasing 54.70 HV than the cold sprayed Al coating. The average coefficient of friction (COF) of cold sprayed Al coating at the wear load of 0.5, 1.0 and 1.5 N is 0.285, 0.239, and 0.435, respectively, while that after LR is 0.243, 0.227, and 0.327, respectively, decreased by 14.73%, 5.02% and 24.83% compared to the cold sprayed Al coating. The wear rate of cold sprayed Al coating at the wear load of 0.5, 1.0 and 1.5 N is 1.60 × 10-4, 2.36 × 10-4, and 2.40 × 10-4 mm³/m·N, respectively, while that after LR is 1.59 × 10-4, 1.70 × 10-4, and 1.94 × 10-4 mm³/m·N, respectively, decreased by 1%, 32%, and 23%, respectively, indicating that LR has high anti-friction performance. Under the wear load action of 1.0 N, the average COF of laser remelted Al coating at the wear speeds of 300, 400 and 500 times/min is 0.294, 0.279, and 0.239, respectively, and the corresponding wear rate is 1.06 × 10-4, 1.24 × 10-4, and 1.70 × 10-4 mm³/m·N, respectively. The wear mechanism of cold sprayed Al coating is primarily corrosion wear at the loads of 0.5 and 1.0 N, and that at the load of 1.5 N is abrasive wear and fatigue wear; while that after LR is abrasive wear and fatigue wear, with no corrosion wear, showing that LR improves its corrosion and wear resistance.
RÉSUMÉ
Cr-Ni coatings with the mass ratios of 17% Cr-83% Ni, 20% Cr-80% Ni and 24% Cr-76% Ni were fabricated on H13 hot work mould steel using a laser cladding (LC). The surface-interface morphologies, chemical elements, surface roughness and phase composition of the obtained Cr-Ni coatings were analysed using a scanning electron microscope (SEM), energy disperse spectroscopy (EDS), atomic force microscope (AFM) and X-ray diffractometer (XRD), respectively. The friction-wear properties and wear rates of Cr-Ni coatings with the different mass ratios of Cr and Ni at 600 °C were investigated, and the worn morphologies and wear mechanism of Cr-Ni coatings were analysed. The results show that the phases of Cr-Ni coatings with mass ratios of 17% Cr-83% Ni, 20% Cr-80% Ni and 24% Cr-76% Ni are composed of Cr + Ni single-phases and their compounds at the different stoichiometry, the porosities on the Cr-Ni coatings increase with the Cr content increasing. The average coefficient of friction (COF) of 17% Cr-83% Ni, 20% Cr-80% Ni and 24% Cr-76% coatings are 1.10, 0.33 and 0.87, respectively, in which the average COF of 20% Cr-80% Ni coating is the lowest, exhibiting the better anti-friction performance. The wear rate of 17% Cr-83% Ni, 20% Cr-80% Ni and 24% Cr-76% Ni coatings is 4.533 × 10-6, 5.433 × 10-6, and 1.761 × 10-6 N-1·s-1, respectively, showing the wear resistance of Cr-Ni coatings at a high temperature increases with the Cr content, in which the wear rate is 24% Cr-76% Ni coating with the better reducing wear. The wear mechanism of 17% Cr-83% Ni and 20% Cr-80% Ni and 24% Cr-76% coatings at 600 °C is primarily adhesive wear, and that of 24% Cr-76% coating is also accompanied by oxidative wear.