Non-Thermal Atmospheric Plasma:Can it Be Taken as a Common Solution for the Surface Treatment of Dental Materials?

This study aimed to evaluate the surface roughness and wetting properties of various dental prosthetic materials after different durations of non-thermal atmospheric plasma（NTAP）treatment.One hundred and sixty discs of titanium（Ti）（n：40）,cobalt chromium（Co-Cr）（n：40）,yttrium stabilized tetragonal zirconia polycrystals（Y-TZP）（n：40）and polymethylmethacrylate（PMMA）（n：40）materials were machined and smoothed with silicon carbide papers.The surface roughness was evaluated in a control group and in groups with different plasma exposure times [1-3-5 s].The average surface roughness（Ra）and contact angle（CA）measurements were recorded via an atomic force microscope（AFM）and tensiometer,respectively.Surface changes were examined with a scanning electron microscope（SEM）.Data were analyzed with two-way analysis of variance（ANOVA）and the Tukey HSD test α=0.05）.According to the results,the NTAP surface treatment significantly affected the roughness and wettability properties（P 〈 0.05）.SEM images reveal that more grooves were present in the NTAP groups.With an increase in the NTAP application time,an apparent increment was observed for Ra,except in the PMMA group,and a remarkable reduction in CA was observed in all groups.It is concluded that the NTAP technology could enhance the roughening and wetting performance of various dental materials.

Effects of internal factors on surface wettability of corn stalk rind

Corn stalk is one of heterogeneous materials with anisotropy and variability.As the rind of corn stalk consists of rich lignin and cellulose similar to wood properties,and possessing high mechanical strength,then can be used as raw material of stalk artificial board and paper.The corn stalk rind has significant differences in fiber morphology,chemical composition and mechanical properties at different heights.Nano-SiO2 composite material contained in the epidermis of corn stalk rind is not conducive to exert adhesive into a board.To study board-making technology by intact corn stalk rind,the wettability of corn stalk rind at different sampling heights is necessary to be analyzed by keeping or removing the epidermis.To analyze the surface wettability difference,the contact angle with water,element compositions and the chemical compositions of corn stalk rind at different sampling heights were studied before and after removal of epidermis.A Fourier transform infrared(FTIR)analysis was performed.The results showed that the removal of the epidermis could significantly improve the hydrophilicity of corn stalk rind.Before removal of the epidermis,the varying contents of elements including C and Si dominate the surface wettability differences at different sampling heights of corn stalk.With an increase in the sampling height,the mass fraction of C increases while that of Si decreases,which result in increasing hydrophilicity.After removal of the epidermis,the surface wettability of corn stalk rind is mainly determined by the mass fraction of hemicellulose,and the higher the sampling height,the larger the mass fraction of hemicellulose resulting in the increase of hydrophilicity.

A thin transition film formed by plasma exposure contributes to the germanium surface hydrophilicity

Plasma treatment and 10% NH_4OH solution rinsing were performed on a germanium（Ge） surface.It was found that the Ge surface hydrophilicity after O_2 and Ar plasma exposure was stronger than that of samples subjected to N_2 plasma exposure. This is because the thin Ge Ox film formed on Ge by O_2 or Ar plasma is more hydrophilic than Ge Ox Ny formed by N_2 plasma treatment. A flat（RMS 〈 0：5 nm） Ge surface with high hydrophilicity（contact angle smaller than 3°） was achieved by O_2 plasma treatment, showing its promising application in Ge low-temperature direct wafer bonding.