H 2PtCl 6 was coordinated with the carboxyl-terminated G4.5PAMAM dendrimer molecules (PAMAMC) in aqueous solution,followed by reduction using NaBH 4 as reducer,and formed Pt-PAMAMC hybrid nano-particles.The stable mul...H 2PtCl 6 was coordinated with the carboxyl-terminated G4.5PAMAM dendrimer molecules (PAMAMC) in aqueous solution,followed by reduction using NaBH 4 as reducer,and formed Pt-PAMAMC hybrid nano-particles.The stable multilayer films were obtained by fabricating diazo resin(DR) with these hybrid nanoparticles (Pt-PAMAMC) and PAMAMC,respectively.The films were subsequently irradiated under UV-light.It was found that the films from Pt-PAMAMC as polyanions exhibit stable frictional responses under the applied load,and the lubricative property of the films from Pt-PAMAMC hybrid nanoparticles is obviously superior to that of the films from dendrimer without platinum inside.展开更多
To improve the performance and reliability of microelectromechanical system＇s devices, it is necessary to understand the effect of friction which exists in the majority of microelectromechanical systems （MEMS） with...To improve the performance and reliability of microelectromechanical system＇s devices, it is necessary to understand the effect of friction which exists in the majority of microelectromechanical systems （MEMS） with a large ratio of surface area to their volume. The model of electrostatic tangential force of the shuttle in laterally driven comb microresonator is established based on the rule of energy conservation. The effects of microscale, surface roughness, applied voltage, and micro asperities or dents or holes formed in fabrication are investigated, and the electrostatic resistance between two charged moving plates is analyzed. The analytic results are coincident well with those of ANSYS simulation. It is found that the electrostatic resistance becomes high as the increase of the ratio of the shuttle width to the gap between moving plates and the relative surface roughness or the increment of the applied voltage.展开更多
TiB2 thin film was deposited by laser-arc deposition method on the surface of single crystalline Silicon. The morphology, composition, structure and microtribological properties of the film were studied by using XPS, ...TiB2 thin film was deposited by laser-arc deposition method on the surface of single crystalline Silicon. The morphology, composition, structure and microtribological properties of the film were studied by using XPS, XRD and atomic force/friction force microscope (AFM/FFM). The results show that TiB2 (100) preferred growth on the Si(100) substrate, TiB2(001) preferred growth on the Si(111) substrate. The TiB2 thin film was composed of TiB2 and a smali amount of TiO2. The friction coefficient of TiB2 film on substrates Si (100) and Si(111) in microtribological process were 0.087 and 0.073, respectively. TiB2 thin film displayed distinct ability of anti-scratch and wear-resistance.展开更多
In this study,the protective effects of two food hydrocolloids,Xanthan gum and Arabic gum,on dental erosion are investigated from the perspective of the nanomechanical properties and microtribological behavior of acid...In this study,the protective effects of two food hydrocolloids,Xanthan gum and Arabic gum,on dental erosion are investigated from the perspective of the nanomechanical properties and microtribological behavior of acid-eroded enamel.Enamel specimens prepared from extracted human teeth were immersed in citric acid solution(CAS),CAS with 0.03%w/v Xanthan gum and CAS with 0.03%w/v Arabic gum,respectively,for 10 min to obtain three groups of eroded specimens.The nanomechanical properties and microtribological behavior of enamel were examined using nano-indentation/scratch techniques.The results show that compared with Arabic gum,Xanthan gum inhibits enamel surface demineralization and acid permeation more effectively because of a more uniform and denser adsorption on the surface of the enamel.The impairment of the nanomechanical and microtribological properties of the enamel surface by acid erosion is mitigated more significantly by adding trace amounts of Xanthan gum than Arabic gum.In summary,adding trace food hydrocolloids reduces enamel surface demineralization and inhibits acid permeation to mitigate the influence of erosion on the mechanical and tribological properties of enamel.The adsorption state of food hydrocolloids is the determining factor in the permeability of acid agents into the enamel and plays a significant role in preventing dental erosion.展开更多
文摘H 2PtCl 6 was coordinated with the carboxyl-terminated G4.5PAMAM dendrimer molecules (PAMAMC) in aqueous solution,followed by reduction using NaBH 4 as reducer,and formed Pt-PAMAMC hybrid nano-particles.The stable multilayer films were obtained by fabricating diazo resin(DR) with these hybrid nanoparticles (Pt-PAMAMC) and PAMAMC,respectively.The films were subsequently irradiated under UV-light.It was found that the films from Pt-PAMAMC as polyanions exhibit stable frictional responses under the applied load,and the lubricative property of the films from Pt-PAMAMC hybrid nanoparticles is obviously superior to that of the films from dendrimer without platinum inside.
基金National Natural Science Foundation of China(No.50135040)Science Foundation of Shanghai Municipality Education Commission through the Key Discipline Program(No.970104).
文摘To improve the performance and reliability of microelectromechanical system＇s devices, it is necessary to understand the effect of friction which exists in the majority of microelectromechanical systems （MEMS） with a large ratio of surface area to their volume. The model of electrostatic tangential force of the shuttle in laterally driven comb microresonator is established based on the rule of energy conservation. The effects of microscale, surface roughness, applied voltage, and micro asperities or dents or holes formed in fabrication are investigated, and the electrostatic resistance between two charged moving plates is analyzed. The analytic results are coincident well with those of ANSYS simulation. It is found that the electrostatic resistance becomes high as the increase of the ratio of the shuttle width to the gap between moving plates and the relative surface roughness or the increment of the applied voltage.
基金This work was supported by the National Natural Science Foundation of China(Grant No.50135040).
文摘TiB2 thin film was deposited by laser-arc deposition method on the surface of single crystalline Silicon. The morphology, composition, structure and microtribological properties of the film were studied by using XPS, XRD and atomic force/friction force microscope (AFM/FFM). The results show that TiB2 (100) preferred growth on the Si(100) substrate, TiB2(001) preferred growth on the Si(111) substrate. The TiB2 thin film was composed of TiB2 and a smali amount of TiO2. The friction coefficient of TiB2 film on substrates Si (100) and Si(111) in microtribological process were 0.087 and 0.073, respectively. TiB2 thin film displayed distinct ability of anti-scratch and wear-resistance.
基金This work was supported by the National Natural Science Foundation of China(Nos.51535010 and 51305366)the Fundamental Research Funds for the Central Universities(No.2682018QY01).
文摘In this study,the protective effects of two food hydrocolloids,Xanthan gum and Arabic gum,on dental erosion are investigated from the perspective of the nanomechanical properties and microtribological behavior of acid-eroded enamel.Enamel specimens prepared from extracted human teeth were immersed in citric acid solution(CAS),CAS with 0.03%w/v Xanthan gum and CAS with 0.03%w/v Arabic gum,respectively,for 10 min to obtain three groups of eroded specimens.The nanomechanical properties and microtribological behavior of enamel were examined using nano-indentation/scratch techniques.The results show that compared with Arabic gum,Xanthan gum inhibits enamel surface demineralization and acid permeation more effectively because of a more uniform and denser adsorption on the surface of the enamel.The impairment of the nanomechanical and microtribological properties of the enamel surface by acid erosion is mitigated more significantly by adding trace amounts of Xanthan gum than Arabic gum.In summary,adding trace food hydrocolloids reduces enamel surface demineralization and inhibits acid permeation to mitigate the influence of erosion on the mechanical and tribological properties of enamel.The adsorption state of food hydrocolloids is the determining factor in the permeability of acid agents into the enamel and plays a significant role in preventing dental erosion.
