Effect of Peroxiredoxin 1 on the biological function of airway epithelial cells and epithelial-mesenchymal transition

Peroxiredoxin 1(PRDX1)participates in tumor cell proliferation,apoptosis,migration,invasion,and the epithelial-to-mesenchymal transition(EMT).This study aimed to investigate the effect of PRDX1 on the EMT of airway epithelial cells stimulated with lipopolysaccharide(LPS)and transforming growth factor-beta 1(TGF-β1).PRDX1 overexpression significantly increased the proliferation and migration of human bronchial epithelial(BEAS-2B)cells,reduced cell apoptosis(p<0.01),and induced EMT and collagen deposition by upregulating the expression of the matrix metallopeptidase(MMP)2,MMP9,α-smooth muscle actin(α-SMA),N-cadherin,vimentin and twist proteins and inhibiting E-cadherin expression(p<0.05).PRDX1 overexpression promoted TGF-β1-mediated inhibition of cell proliferation and migration and significantly enhanced the TGF-β1-induced EMT and collagen synthesis(p<0.05).Knockdown of PRDX1 inhibited cell proliferation,migration,EMT,and collagen synthesis(p<0.01),reversed LPS-mediated inhibition of cell proliferation and migration,and significantly suppressed LPS-induced EMT and collagen synthesis(p<0.01).The result indicating that PRDX1 may be involved in LPS/TGF-1-induced EMT and collagen synthesis in human bronchial epithelial cells.

Effect of functional groups on tribological properties of lubricants and mechanism investigation

Nine organic compounds were utilized as model lubricants to investigate the impact of functional groups on tribological performances.Nonanoic Acid with carboxyl showed the best lubrication properties,and fluid film and tribofilm were coexistent in its friction test,bringing a low friction coefficient and wear rate.In addition,the lubricant with low friction coefficient corresponded to high adsorption energy in density functional theory(DFT)calculations.And the lubricant forming adsorption film with large surface energy displayed small wear rate in friction test.Moreover,adsorption energies positively correlated surface energies.Based on the experimental results,the action mechanism of functional groups on tribological properties of lubricants was proposed.Various functional groups make lubricant molecules show different adsorption energies and surface energies.Lubricant molecules with high adsorption energy are more likely to adsorb on substrates and form a vertical monolayer,which can maintain a regular molecular brush structure during friction and bring a low friction coefficient.And lubricant molecules with high surface energy may be more prone having tribochemical reactions during friction and forming protective tribofilm,which leads to a low wear rate.

Hydrophobic, mechanical, and tribological properties of fluorine incorporated hydrogenated fullerene-like carbon films

Fluorine-incorporated hydrogenated fullerene-like nanostructure amorphous carbon films(F-FLC)were synthesized by employing the direct current plasma enhanced chemical vapor deposition(dc-PECVD)technique using a mixture of methane(CH4),tetra-fluoromethane(CF4),and hydrogen(H2)as the working gases.The effect of the fluorine content on the bonding structure,surface roughness,hydrophobic,mechanical,and tribological properties of the films was systematically investigated using Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),Raman analysis,atomic force microscope(AFM),contact angle goniometer,nano-indenter,and reciprocating ball-on-disc tester,respectively.The fluorine content in the films increased from 0 to 2.1 at.%as the CF4 gas flow ratio increased from 0 to 3 sccm,and incorporated fluorine atoms existed in the form of C-FX(X=1,2,3)bonds in the film.The fullerene nanostructure embedded in the hydrogenated amorphous carbon films was confirmed by Raman analysis.The water contact angle was significantly increased because of fluorine doping,which indicates that the hydrophobicity of the carbon films could be adjusted to some extent by the fluorine doping.The hardness and elastic modulus of the films remained relatively high(22 GPa)as the fluorine content increased.Furthermore,the friction coefficient of the carbon films was significantly reduced and the wear resistance was enhanced by fluorine doping.

Adhesion and friction performance of DLC/rubber:The influence of plasma pretreatment

Diamond-like carbon(DLC)films are deposited on rubber surfaces to protect the rubber components,and surface pretreatment of the rubber substrates prior to the film deposition can improve the adhesion between the DLC films and the rubber.Thus,the principal purpose of this work concentrates on determining the effects of argon(Ar),oxygen(O_(2)),nitrogen(N_(2)),and hydrogen(H_(2))plasma pretreatments on the adhesion and friction performance of the DLC films deposited on rubber(DLC/rubber).The results indicated that the Ar plasma pretreatment promoted the formation of a compact layer on the rubber surface.By contrast,massive fillers were exposed on the rubber surface after oxygen or nitrogen plasma pretreatments.Moreover,the typical micrometer-scale patches divided by random cracks were observed on the surface of DLC/rubber,except for the sample pretreated with oxygen plasma.The adhesion of DLC/rubber was found to strengthen with the removal of weak boundary layers and the generation of free radicals on the rubber surface after plasma pretreatment.The tribo-tests revealed that DLC/rubber with O_(2),N_(2),and H_(2) plasma pretreatments cannot achieve optimal friction performance.Significantly,DLC/rubber with Ar plasma pretreatment exhibited a low and stable friction coefficient of 0.19 and superior wear resistance,which was correlated to the high adhesion,good load-bearing of the rubber surface,and the approximate sine function of the surface profile of the DLC film.