A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are...A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.展开更多
Recently,the issue of bacterial resistance has gotten worse because of the overuse of antibiotics.The newborn superbacteria,such as vancomycin-resistant bacteria,were hard to kill,inspiring researchers to find new way...Recently,the issue of bacterial resistance has gotten worse because of the overuse of antibiotics.The newborn superbacteria,such as vancomycin-resistant bacteria,were hard to kill,inspiring researchers to find new ways to kill the bacteria efficiently.TiO_(2) was used as an efficient photocatalyst for water split-ting and pollutant degradation.However,the weak efficiency limited the application to solve the drug-resistance problem.Consequently,the incorpora-tion of low-cost 0D carbon quantum dots(CQDs)and 2D graphene oxide(GO)was pursued to amplify the visible light absorption capabilities of TiO_(2) and thereby elevate its photocatalytic activity.After forming the heterogeneous interface of CQDs and TiO_(2),CQDs converted part of visible light into wave-length less than 400 nm using the up-conversion property.The modification of CQDs enabled electrons to be easily transferred from the conduction band of CQDs to the conduction band of TiO_(2).Meanwhile,GO can act as an electron acceptor,reduce the recombination efficiency of holes and electrons,and transfer the photogenerated electrons in the redox reaction in the heterogeneous interface.Because of the excellent absorption of GO,TiO_(2)/CQDs/GO reached 57.8℃after 20 min irradiation under 1.5 times sunlight,which provided a prerequisite for photodynamic antibacterial therapy/photothermal antibacterial therapy synergistic antibacterial potential.TiO_(2)/CQDs/GO possessed an anti-bacterial efficiency as high as 99.3%toward Staphylococcus aureus which has a bright future in disinfection in vivo and medical devices as well as water sterilization.展开更多
A TiO2 nanofilm was prepared on the surface of AZ31 magnesium alloy with controllable thickness through atomic layer deposition(ALD) technique, which can adjust the corrosion behaviors of AZ31 Mg alloy.Compared with t...A TiO2 nanofilm was prepared on the surface of AZ31 magnesium alloy with controllable thickness through atomic layer deposition(ALD) technique, which can adjust the corrosion behaviors of AZ31 Mg alloy.Compared with the untreated Mg alloys, corrosion current densities(icorr)can decline by 58% in the 200-cycles TiO2-covered Mg alloy and further decline by up to 74% with the thickness of nanofilm up to 63 nm(400 cycles).The subsequent modification with a cross-linked conversion layer of 3-aminopropyltriethoxysilane(APTES) by a dipping method can produce a compact silane coating on TiO2 nanofilm, which can seal pinholes of TiO2 nanofilm and serve as a barrier to further adjust the corrosion behavior of the substrate.The icorrcan decline about two orders of magnitude in the TiO2/silane composite coating.Making the adjustable corrosion rate come true, which can be attributed to the precise control on the thickness of metal oxide nanofilm and additional protection from the compact silane coating.In vitro study discloses that the TiO2/silane hybrid coating shows higher expression of alkaline phosphatase(ALP)and can promote cellular adhesion and proliferation with better cytocompatibility than untreated Mg alloy.展开更多
Because of the impressive evolution of the drugresistant bacteria,the development of efficient,antibioticfree agent is in great urgency.Herein,an efficient antibacterial agent,CuS@HKUST-polydopamine(PDA),was exquisite...Because of the impressive evolution of the drugresistant bacteria,the development of efficient,antibioticfree agent is in great urgency.Herein,an efficient antibacterial agent,CuS@HKUST-polydopamine(PDA),was exquisitely designed,where the Cu-based metal-organic framework(MOF)—HKUST nanoparticles served as the porous frame,and the CuS was synthesized within the structure of the MOF through the process of in situ sulfuration,followed with polydopamine(PDA)covering the nanoparticles.The structure of the HKUST preventing the aggregation of the CuS nanoparticles,which improved their photothermal and photocatalytic properties.After covering with PDA,the nanoparticles’abilities to produce heat and free radicals were further enhanced.This was because that the PDA itself could transform light into heat,which not only benefited the photothermal property,but also improved the photocatalytic property of the nanoparticles by accelerating the charge mobility.Moreover,the PDA could also transfer the photo-induced electrons fast and thus prevented the recombination of the photo-generated electron–hole pairs,which resulted in the enhanced ability to produce free radicals.As a result,under light irradiation,the antibacterial efficiency of the CuS@HKUST-PDA against Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)could reach 99.77%and 99.57%.Hence,the synthesized CuS@HKUST-PDA can be promising for anti-infection and sterilization application without using antibiotics.展开更多
Controlling the corrosion rate is critical for practical applications of Mg-based alloys. In this work, we constructed a protective coating of hybrid polycaprolactone(H-PCL)/indocyanine green(ICG) on AZ31 Mg alloy,who...Controlling the corrosion rate is critical for practical applications of Mg-based alloys. In this work, we constructed a protective coating of hybrid polycaprolactone(H-PCL)/indocyanine green(ICG) on AZ31 Mg alloy,whose degradation rate was controlled by 808-nm nearinfrared(NIR) light irradiation. The corrosion behaviors of H-PCL/ICG coated Mg alloys were systematically investigated by potentiodynamic polarization tests, electrochemical impedance spectroscopy(EIS) and hydrogen evolution experiments. The results disclosed that the H-PCL/ICG composite coating could effectively protect Mg alloy from corroding without NIR light irradiation. In contrast, under 808-nm NIR light irradiation, the corrosion resistance of this composite coating was decreased significantly, i.e., the corrosion current density(i_(corr))increasedfrom(8.81 ± 1.068) 9 10^(-8) to(1.22 ± 0.545) 9 10^(-6) A·cm^(-2). This is because the component of ICG in the coating was excited to produce heat locally, which triggered the glass transition temperature(T_(g)) of H-PCL in the coating, resulting in the motion of the molecular chain segment. Consequently, the electrolytes penetrated the coating and corroded the Mg substrate. In vitro biological experiment indicated that the synthesized coating exhibited good cytocompatibility.Hence, these findings will provide a new strategy for designing novel photoresponsive coatings to remotely adjust the degradation rate of biodegradable metals for biomedical applications.展开更多
基金Supported by the Fundamental Research Funds in Heilongjiang Provincial Universities of China under Grant No 135209312
文摘A two-dimensional self-consistent fluid model is employed to investigate radio-frequency process parameters on the plasma properties in Ar microdischarges. The neutral gas density and temperature balance equations are taken into account. We mainly investigate the effect of the electrode gap on the spatial distribution of the electron density and electron temperature profiles, due to a mode transition from the regime（secondary electrons emission is responsible for the significant ionization） to the regime（sheath oscillations and bulk electrons are responsible for sustaining discharge） induced by a sudden decrease of electron density and electron temperature.The pressure, radio-frequency sources frequency and voltage effects on the electron density are also elaborately investigated.
基金supported by the China National Funds for Distinguished Young Scientists(No.51925104)the National Natural Science Foundation of China(NSFC)(No.52173251)+3 种基金NSFC-Guangdong Province Joint Program(Key program No.U21A2084)Yanzhao Young Scientist Project(No.C2023202018)Beijing Natural Science Foundation(No.7232338)the Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.226Z1303G).
文摘Recently,the issue of bacterial resistance has gotten worse because of the overuse of antibiotics.The newborn superbacteria,such as vancomycin-resistant bacteria,were hard to kill,inspiring researchers to find new ways to kill the bacteria efficiently.TiO_(2) was used as an efficient photocatalyst for water split-ting and pollutant degradation.However,the weak efficiency limited the application to solve the drug-resistance problem.Consequently,the incorpora-tion of low-cost 0D carbon quantum dots(CQDs)and 2D graphene oxide(GO)was pursued to amplify the visible light absorption capabilities of TiO_(2) and thereby elevate its photocatalytic activity.After forming the heterogeneous interface of CQDs and TiO_(2),CQDs converted part of visible light into wave-length less than 400 nm using the up-conversion property.The modification of CQDs enabled electrons to be easily transferred from the conduction band of CQDs to the conduction band of TiO_(2).Meanwhile,GO can act as an electron acceptor,reduce the recombination efficiency of holes and electrons,and transfer the photogenerated electrons in the redox reaction in the heterogeneous interface.Because of the excellent absorption of GO,TiO_(2)/CQDs/GO reached 57.8℃after 20 min irradiation under 1.5 times sunlight,which provided a prerequisite for photodynamic antibacterial therapy/photothermal antibacterial therapy synergistic antibacterial potential.TiO_(2)/CQDs/GO possessed an anti-bacterial efficiency as high as 99.3%toward Staphylococcus aureus which has a bright future in disinfection in vivo and medical devices as well as water sterilization.
基金financially supported by the Natural Science Fund of Hubei Province (No.2018CFA064)the National Natural Science Foundation of China (NSFC) (Nos.51671081 and 51422102)+4 种基金the National Key Research and Development Program of China (No.2016YFC1100600, sub-project 2016YFC1100604)the Hong Kong Research Grants Council (RGC) General Research Funds (GRF) (Nos.11301215, 11205617 and 17214516)RGC/NSFC (N_HKU725-16)the Hong Kong Innovation and Technology Commission (ITC) (Nos.ITS/287/17 and GHX/002/14SZ)the Health and Medical Research Fund (No.03142446)
文摘A TiO2 nanofilm was prepared on the surface of AZ31 magnesium alloy with controllable thickness through atomic layer deposition(ALD) technique, which can adjust the corrosion behaviors of AZ31 Mg alloy.Compared with the untreated Mg alloys, corrosion current densities(icorr)can decline by 58% in the 200-cycles TiO2-covered Mg alloy and further decline by up to 74% with the thickness of nanofilm up to 63 nm(400 cycles).The subsequent modification with a cross-linked conversion layer of 3-aminopropyltriethoxysilane(APTES) by a dipping method can produce a compact silane coating on TiO2 nanofilm, which can seal pinholes of TiO2 nanofilm and serve as a barrier to further adjust the corrosion behavior of the substrate.The icorrcan decline about two orders of magnitude in the TiO2/silane composite coating.Making the adjustable corrosion rate come true, which can be attributed to the precise control on the thickness of metal oxide nanofilm and additional protection from the compact silane coating.In vitro study discloses that the TiO2/silane hybrid coating shows higher expression of alkaline phosphatase(ALP)and can promote cellular adhesion and proliferation with better cytocompatibility than untreated Mg alloy.
基金This work was financially supported by Jilin Provincial Science and Technology Project(No.YDZJ202101-ZYTS054)the National Science Fund for Distinguished Young Scholars(No.51925104)the National Natural Science Foundation of China(No.51871162).
文摘Because of the impressive evolution of the drugresistant bacteria,the development of efficient,antibioticfree agent is in great urgency.Herein,an efficient antibacterial agent,CuS@HKUST-polydopamine(PDA),was exquisitely designed,where the Cu-based metal-organic framework(MOF)—HKUST nanoparticles served as the porous frame,and the CuS was synthesized within the structure of the MOF through the process of in situ sulfuration,followed with polydopamine(PDA)covering the nanoparticles.The structure of the HKUST preventing the aggregation of the CuS nanoparticles,which improved their photothermal and photocatalytic properties.After covering with PDA,the nanoparticles’abilities to produce heat and free radicals were further enhanced.This was because that the PDA itself could transform light into heat,which not only benefited the photothermal property,but also improved the photocatalytic property of the nanoparticles by accelerating the charge mobility.Moreover,the PDA could also transfer the photo-induced electrons fast and thus prevented the recombination of the photo-generated electron–hole pairs,which resulted in the enhanced ability to produce free radicals.As a result,under light irradiation,the antibacterial efficiency of the CuS@HKUST-PDA against Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)could reach 99.77%and 99.57%.Hence,the synthesized CuS@HKUST-PDA can be promising for anti-infection and sterilization application without using antibiotics.
基金jointly supported by the Natural Science Fund of Hubei Province(No.2018CFA064)the National Natural Science Foundation of China(Nos.51871162 and 51671081)+3 种基金the National Science Fund for Distinguished Young Scholars(No.51925104)the Key Program of National Natural Science Foundation of China(No.51631007)Hong Kong ITC(Nos.ITS/287/17 and GHX/002/14SZ)the Health and Medical Research Fund(No.03142446)。
文摘Controlling the corrosion rate is critical for practical applications of Mg-based alloys. In this work, we constructed a protective coating of hybrid polycaprolactone(H-PCL)/indocyanine green(ICG) on AZ31 Mg alloy,whose degradation rate was controlled by 808-nm nearinfrared(NIR) light irradiation. The corrosion behaviors of H-PCL/ICG coated Mg alloys were systematically investigated by potentiodynamic polarization tests, electrochemical impedance spectroscopy(EIS) and hydrogen evolution experiments. The results disclosed that the H-PCL/ICG composite coating could effectively protect Mg alloy from corroding without NIR light irradiation. In contrast, under 808-nm NIR light irradiation, the corrosion resistance of this composite coating was decreased significantly, i.e., the corrosion current density(i_(corr))increasedfrom(8.81 ± 1.068) 9 10^(-8) to(1.22 ± 0.545) 9 10^(-6) A·cm^(-2). This is because the component of ICG in the coating was excited to produce heat locally, which triggered the glass transition temperature(T_(g)) of H-PCL in the coating, resulting in the motion of the molecular chain segment. Consequently, the electrolytes penetrated the coating and corroded the Mg substrate. In vitro biological experiment indicated that the synthesized coating exhibited good cytocompatibility.Hence, these findings will provide a new strategy for designing novel photoresponsive coatings to remotely adjust the degradation rate of biodegradable metals for biomedical applications.
