Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sin...Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite(F)structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore(P)and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m^(-1)K^(-1)at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients(TECs)of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3×10^(-6)K^(-1) in temperature range between 200-1200℃.展开更多
Linalool,a major component of aromatic plant essential oils,has an antibacterial effect against Hafnia alvei,which can induce food spoilage.In this study,we aimed to investigate the antibacterial effect and mechanism ...Linalool,a major component of aromatic plant essential oils,has an antibacterial effect against Hafnia alvei,which can induce food spoilage.In this study,we aimed to investigate the antibacterial effect and mechanism of linalool against H.alvei.Linalool treatment resulted in excessive reactive oxygen species(ROS)accumulation,which resulted in destruction of the cell membrane.According to the field emission scanning electron microscopy(FESEM)and flow cytometry(FCM)results,it was confirmed that the membrane structure of H.alvei was destroyed.Moreover,metabolomics analysis showed that there were 64 and 73 differentially expressed metabolites screened by mass spectrometry in positive and negative ion modes,respectively,suggesting that nucleic acid metabolism,the respiratory chain and energy metabolism were negatively affected by linalool.Biochemical validation confirmed that the activities of malate dehydrogenase(MDH),and succinate dehydrogenase(SDH)and respiratory metabolism were reduced after linalool treatment.It was therefore concluded that the cell membrane was damaged,nucleic acid metabolism was disturbed,and energy metabolism was reduced by inhibition of the respiratory chain and tricarboxylic acid(TCA)cycle.These results revealed the antibacterial mechanism of linalool against H.alvei,and support the use of linalool as a potential natural preservative to control H.alvei.展开更多
基金supported financially by the National Natural Science Foundation of China(Nos.U1537212,51971013,51590894and 51425102)the National Key Research and Development Program of China(No.2016YFB0300901)。
文摘Rare earth oxides doped hafnia ceramics,with a formula of Hf0.76LnxY0.24-xO1.88(Ln=Gd,Yb,Gd+Yb or La+Yb),were prepared by solid state sintering at 1500℃.The effects of the rare earth oxides on the microstructures,sintering resistance,and thermo-physical properties of the doped hafnia ceramics were investigated.Results show that the Gd-Y,Yb-Y or Gd-Yb-Y co-doped hafnia ceramics remain the same defect fluorite(F)structure,while the La-Yb-Y co-doped hafnia revealing coexistence of pyrochlore(P)and fluorite structures.Yb-Y co-doped samples exhibited much better sintering resistance compared with Gd-Y and Gd-Yb-Y co-doped samples.The coexistence of P and F phases is beneficial to improved sintering capability.The thermal conductivities of the Gd-Y,Yb-Y and Gd-Yb-Y doped samples are relatively lower(1.4-1.7 W m^(-1)K^(-1)at 1200℃),but for the La-Yb-Y co-doped samples,the thermal conductivity increases dramatically with temperature due to increased thermal radiation at high-temperature.The average thermal expansion coefficients(TECs)of the Gd-Y,Yb-Y and Gd-Yb-Y co-doped samples are as high as10.3×10^(-6)K^(-1) in temperature range between 200-1200℃.
基金the National Natural Science Foundation of China(No.32160591)for financial support.
文摘Linalool,a major component of aromatic plant essential oils,has an antibacterial effect against Hafnia alvei,which can induce food spoilage.In this study,we aimed to investigate the antibacterial effect and mechanism of linalool against H.alvei.Linalool treatment resulted in excessive reactive oxygen species(ROS)accumulation,which resulted in destruction of the cell membrane.According to the field emission scanning electron microscopy(FESEM)and flow cytometry(FCM)results,it was confirmed that the membrane structure of H.alvei was destroyed.Moreover,metabolomics analysis showed that there were 64 and 73 differentially expressed metabolites screened by mass spectrometry in positive and negative ion modes,respectively,suggesting that nucleic acid metabolism,the respiratory chain and energy metabolism were negatively affected by linalool.Biochemical validation confirmed that the activities of malate dehydrogenase(MDH),and succinate dehydrogenase(SDH)and respiratory metabolism were reduced after linalool treatment.It was therefore concluded that the cell membrane was damaged,nucleic acid metabolism was disturbed,and energy metabolism was reduced by inhibition of the respiratory chain and tricarboxylic acid(TCA)cycle.These results revealed the antibacterial mechanism of linalool against H.alvei,and support the use of linalool as a potential natural preservative to control H.alvei.
