In this study,Mg-based composites,by the addition of ZnO,Ca_(2)ZnSi_(2)O_(7),Ca_(2)MgSi_(2)O_(7),and CaSiO_(3)as bioactive agents,were fabricated using friction stir processing.The microstructure and in vitro assessme...In this study,Mg-based composites,by the addition of ZnO,Ca_(2)ZnSi_(2)O_(7),Ca_(2)MgSi_(2)O_(7),and CaSiO_(3)as bioactive agents,were fabricated using friction stir processing.The microstructure and in vitro assessment of bioactivity,biodegradation rate,and corrosion behavior of the resultant composites were investigated in simulated body fluid(SBF).The results showed that during the immersion of composites in SBF for 28 d,due to the release of Ca^(2+)and PO_(4)^(3-)ions,hydroxyapatite(HA)crystals with cauliflower shaped morphology were deposited on the surface of composites,confirming good bioactivity of composites.In addition,due to the uniform distribution of bioceramic powders throughout Mg matrix,grain refinement of the Mg matrix,and uniform redistribution of secondary phase particles,the polarization resistance increased,and the biodegradation rate of composites significantly reduced compared to monolithic Mg matrix.The polarization corrosion resistance of Mg-ZnO increased from 0.216 to 2.499 kΩ/cm^(2)compared to monolithic Mg alloy.Additionally,Mg-ZnO composite with the weight loss of 0.0217 g after 28 d immersion showed lower weight loss compared to other samples with increasing immersion time.Moreover,Mg-ZnO composite with the biodegradation rate of 37.71 mm/a exhibited lower biodegradation rate compared to other samples with increasing immersion time.展开更多
Diallyl disulfide was synthesized by phase transfer catalyst （PTC） during microwave irradiation. The effects of different factors, such as the power of microwave irradiation, the time of microwave irradiation, PTC r...Diallyl disulfide was synthesized by phase transfer catalyst （PTC） during microwave irradiation. The effects of different factors, such as the power of microwave irradiation, the time of microwave irradiation, PTC reagents amount and the mole ratio of reactants, on the yield of product were investigated. The structure of diallyl disulfide was characterized by infrared spectra, mass spectra and ^1 H nuclear magnetic resonance. The bioactivity of diallyl disulfide was evaluated by cell viability assay on HepG2 hepatoma cells. The results show that the optimal reaction conditions are as follows： tetrabutylammonium bromide（TBAB） selected as a PTC, the mass ratio of TBAB to sodium disulfide of 0.021 ： 1, the power of irradiation of 195 W, the reaction time of 12 rain, and the mole ratio of sodium disulfide to allyl chloride of 0.65 ： 1. The yield of diallyl disulfide is 82.2%. The synthetical diallyl disulfide appears to be cytotoxic to HepG2 heoatoma cells in a dose-dependent manner.展开更多
Essential oil （EO） of Nigeria-grown Lippia adoensis leaf was analyzed using gas chromatography mass spectrometry （GCMS） and its fumigant and repellent properties against Callosobruchus maculatus were evaluated. Si...Essential oil （EO） of Nigeria-grown Lippia adoensis leaf was analyzed using gas chromatography mass spectrometry （GCMS） and its fumigant and repellent properties against Callosobruchus maculatus were evaluated. Sixteen compounds predominated by monoterpenes were identified. The major compounds were Eucalyptol （28.36%）, α-Terpineol （25.99%）, γ-Terpinene （15.24%）, α-Pinene （5.08%）, 1H-Cyclopropa[a]naphthalene （4.25%） and 1, 3, 6, 10-Dodeeatetraene （3.74%）. Percentage mortality due to fumigant toxicity was dose- and exposure period-dependent. One hour after treatment （HAT）, application of L. adoensis leaf EO at 107 μL· L^-1 air caused significantly （p〈0.05） higher mortality （50.00%） than 0.00% mortality observed at 0-53 μL· L^-1 air, but not significantly （p〉0.05） different from 22.50% observed in 80 μL· L^-1 air. At 3 HAT, application ofL. adoensis EO at 80 μL· L^-1 air caused significantly higher mortality （90.00 %） than mortality observed at 0 μL· L^-1 air. At 6 HAT, application of L. adoensis EO at 53-107 μL· L^-1 air caused significantly higher mortality （100.00 %） than that was observed in the control. The same trend was observed at 12 HAT where 100 % mortality observed in 27-107 μL· L^-1 air was significantly greater than 13.33 % observed in the control. At 3 HAT, percentage repellence was significantly （p〈0.05） affected by doses. Application of EO at 10-30 μL· cm^2 caused class V repellence （86.67%-100%） compared with the control which caused class I repellence （0-20%）.展开更多
文摘In this study,Mg-based composites,by the addition of ZnO,Ca_(2)ZnSi_(2)O_(7),Ca_(2)MgSi_(2)O_(7),and CaSiO_(3)as bioactive agents,were fabricated using friction stir processing.The microstructure and in vitro assessment of bioactivity,biodegradation rate,and corrosion behavior of the resultant composites were investigated in simulated body fluid(SBF).The results showed that during the immersion of composites in SBF for 28 d,due to the release of Ca^(2+)and PO_(4)^(3-)ions,hydroxyapatite(HA)crystals with cauliflower shaped morphology were deposited on the surface of composites,confirming good bioactivity of composites.In addition,due to the uniform distribution of bioceramic powders throughout Mg matrix,grain refinement of the Mg matrix,and uniform redistribution of secondary phase particles,the polarization resistance increased,and the biodegradation rate of composites significantly reduced compared to monolithic Mg matrix.The polarization corrosion resistance of Mg-ZnO increased from 0.216 to 2.499 kΩ/cm^(2)compared to monolithic Mg alloy.Additionally,Mg-ZnO composite with the weight loss of 0.0217 g after 28 d immersion showed lower weight loss compared to other samples with increasing immersion time.Moreover,Mg-ZnO composite with the biodegradation rate of 37.71 mm/a exhibited lower biodegradation rate compared to other samples with increasing immersion time.
基金Project (C03050205) supported by the National Natural Science Foundation of China
文摘Diallyl disulfide was synthesized by phase transfer catalyst （PTC） during microwave irradiation. The effects of different factors, such as the power of microwave irradiation, the time of microwave irradiation, PTC reagents amount and the mole ratio of reactants, on the yield of product were investigated. The structure of diallyl disulfide was characterized by infrared spectra, mass spectra and ^1 H nuclear magnetic resonance. The bioactivity of diallyl disulfide was evaluated by cell viability assay on HepG2 hepatoma cells. The results show that the optimal reaction conditions are as follows： tetrabutylammonium bromide（TBAB） selected as a PTC, the mass ratio of TBAB to sodium disulfide of 0.021 ： 1, the power of irradiation of 195 W, the reaction time of 12 rain, and the mole ratio of sodium disulfide to allyl chloride of 0.65 ： 1. The yield of diallyl disulfide is 82.2%. The synthetical diallyl disulfide appears to be cytotoxic to HepG2 heoatoma cells in a dose-dependent manner.
基金Supported by the Senate of Ladoke Akintola University of Technology(LAUTECH)Ogbomoso,Nigeria Under the University Senate Research(LAU/SRG/13/045)
文摘Essential oil （EO） of Nigeria-grown Lippia adoensis leaf was analyzed using gas chromatography mass spectrometry （GCMS） and its fumigant and repellent properties against Callosobruchus maculatus were evaluated. Sixteen compounds predominated by monoterpenes were identified. The major compounds were Eucalyptol （28.36%）, α-Terpineol （25.99%）, γ-Terpinene （15.24%）, α-Pinene （5.08%）, 1H-Cyclopropa[a]naphthalene （4.25%） and 1, 3, 6, 10-Dodeeatetraene （3.74%）. Percentage mortality due to fumigant toxicity was dose- and exposure period-dependent. One hour after treatment （HAT）, application of L. adoensis leaf EO at 107 μL· L^-1 air caused significantly （p〈0.05） higher mortality （50.00%） than 0.00% mortality observed at 0-53 μL· L^-1 air, but not significantly （p〉0.05） different from 22.50% observed in 80 μL· L^-1 air. At 3 HAT, application ofL. adoensis EO at 80 μL· L^-1 air caused significantly higher mortality （90.00 %） than mortality observed at 0 μL· L^-1 air. At 6 HAT, application of L. adoensis EO at 53-107 μL· L^-1 air caused significantly higher mortality （100.00 %） than that was observed in the control. The same trend was observed at 12 HAT where 100 % mortality observed in 27-107 μL· L^-1 air was significantly greater than 13.33 % observed in the control. At 3 HAT, percentage repellence was significantly （p〈0.05） affected by doses. Application of EO at 10-30 μL· cm^2 caused class V repellence （86.67%-100%） compared with the control which caused class I repellence （0-20%）.
