The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe...The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe force microscopy(SKPFM)and computational methods.Results showed that the corrosion resistance of Mg-8Li-3Al alloy in NaCl solution was effectively improved with SDS.The SEM and SKPFM results confirmed a dense,200 nm-thick SDS-adsorbed layer had formed on the alloy surface.The separation energy ΔE_(gap) and adsorption energy E_(ads) of SDS on the Mg surface were calculated by density functional theory and molecular dynamics simulations,respectively.And the corrosion inhibition mechanism was hypothesized and described.展开更多
Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To ...Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To be applied more widely, active metasurface devices are highly desired. Here, a tunable terahertz meta-lens whose focal length is able to be electrically tuned by ～4.45λ is demonstrated experimentally. The lens consists of a metallic metasurface and a monolayer graphene. Due to the dependence of the abrupt phase change of the metasurface on the graphene chemical potential, which can be modulated using an applied gate voltage, the focal length is changed from 10.46 to 12.24 mm when the gate voltage increases from 0 to 2.0 V. Experimental results are in good agreement with the theoretical hypothesis. This type of electrically controlled meta-lens could widen the application of terahertz technology.展开更多
Sterol C24-methyltransferase(SMT) plays multiple important roles in plant growth and development. SMT1, which belongs to the family of transferases and transforms cycloartenol into 24-methylene cycloartenol, is involv...Sterol C24-methyltransferase(SMT) plays multiple important roles in plant growth and development. SMT1, which belongs to the family of transferases and transforms cycloartenol into 24-methylene cycloartenol, is involved in the biosynthesis of 24-methyl sterols. Here, we report the cloning and characterization of a cDNA encoding a sterol C24-methyltransferase from Tripterygium wilfordii(Tw SMT1). Tw SMT1(Gen Bank access number KU885950) is a 1530 bp cDNA with a 1041 bp open reading frame predicted to encode a 346-amino acid, 38.62 k Da protein. The polypeptide encoded by the SMT1 cDNA was expressed and purified as a recombinant protein from Escherichia coli(E. coli) and showed SMT activity. The expression of Tw SMT1 was highly up-regulated in T. wilfordii cell suspension cultures treated with methyl jasmonate(Me JA). Tissue expression pattern analysis showed higher expression in the phellem layer compared to the other four organs(leaf, stem, xylem and phloem), which is about ten times that of the lowest expression in leaf. The results are meaningful for the study of sterolbiosynthesis of T. wilfordii and will further lay the foundations for the research in regulating both the content of other main compounds and growth and development of T. wilfordii.展开更多
The Hα imaging spectrograph(HIS) is the scientific payload of the first solar space mission, the Chinese Hα solar explorer(CHASE), supported by the China National Space Administration(CNSA). The CHASE/HIS achieves, ...The Hα imaging spectrograph(HIS) is the scientific payload of the first solar space mission, the Chinese Hα solar explorer(CHASE), supported by the China National Space Administration(CNSA). The CHASE/HIS achieves, for the first time in space, Hα spectroscopic observations with high spectral and temporal resolutions. Separate channels for the raster scanning mode(RSM) and continuum imaging mode(CIM) are integrated into one, and a highly integrated design is achieved through multiple folding of the optical path and ultra-light miniaturized components. The design of HIS implements a number of key technologies such as high-precision scanning of the optical field of view(FOV), high-precision integrated manufacturing inspection, a large-tolerance pre-filter window, and full-link solar radiation calibration. The HIS instrument has a pixel spectral resolution of 0.024 ? and can complete a full-Sun scanning within 46 s.展开更多
of main observation and conclusion Paraffin,as an excellent phase change material(PCM),is limited by the leakage problem and low thermal conductivity.In this research,a novel paraffin/neopentyl glycol dimethacrylate/b...of main observation and conclusion Paraffin,as an excellent phase change material(PCM),is limited by the leakage problem and low thermal conductivity.In this research,a novel paraffin/neopentyl glycol dimethacrylate/boron nitride(paraffin/NPGDMA/BN)composite PCM was successfully prepared via a physical mixing process.NPGDMA in paraffin/NPGDMA/BN composite PCM was cured by UV light under the action of photo initiator,which can improve the shape stability to avoid the leakage of paraffin in the process of phase change.By comparing the leakage rate,latent heat,and thermal conductivity,the optimal mass ratio of paraffin and NPGDMA was selected to be 7:3.It was showed that the presence of 5 wt%BN led to increasing in thermal conductivity by up to 59%.The microstructure of the composite PCMs was characterized by SEM,FTIR,and XRD.The composite PCMs can be processed into a variety of shapes by using molds.The paraffin/NPGDMA/BN composite PCM exhibited a significantly improved shape stability and large phase change enthalpy of 123.0 J/g.The leakage rate of paraffin/NPGDMA/BN was much improved after being soaked with petroleum ether.展开更多
基金the financial support by the National Natural Science Foundation of China(51961026)the Interdisciplinary Innovation Fund of Nanchang University(Project No.2019-9166-27060003)。
文摘The corrosion inhibition behavior of Mg-8Li-3Al alloy in NaCl solution with sodium dodecyl sulfate(SDS)was investigated by hydrogen analysis,scanning electron microscopy(SEM),electrochemical test,scanning Kelvin probe force microscopy(SKPFM)and computational methods.Results showed that the corrosion resistance of Mg-8Li-3Al alloy in NaCl solution was effectively improved with SDS.The SEM and SKPFM results confirmed a dense,200 nm-thick SDS-adsorbed layer had formed on the alloy surface.The separation energy ΔE_(gap) and adsorption energy E_(ads) of SDS on the Mg surface were calculated by density functional theory and molecular dynamics simulations,respectively.And the corrosion inhibition mechanism was hypothesized and described.
基金National Key R&D Program of China(2017YFB1002900)973 Program of China(2013CBA01702)+1 种基金National Natural Science Foundation of China(NSFC)(11404224,1174243,11774246,61405012,61420106014)Excellent Young Scholars Research Fund of Beijing Institute of Technology(BIT)
文摘Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To be applied more widely, active metasurface devices are highly desired. Here, a tunable terahertz meta-lens whose focal length is able to be electrically tuned by ～4.45λ is demonstrated experimentally. The lens consists of a metallic metasurface and a monolayer graphene. Due to the dependence of the abrupt phase change of the metasurface on the graphene chemical potential, which can be modulated using an applied gate voltage, the focal length is changed from 10.46 to 12.24 mm when the gate voltage increases from 0 to 2.0 V. Experimental results are in good agreement with the theoretical hypothesis. This type of electrically controlled meta-lens could widen the application of terahertz technology.
基金supported by the National Natural Science Foundation of China (81422053 and 81373906 to Wei Gao and 81325023 to Luqi Huang)the Support Project of High-level Teachers in Beijing Municipal Universities in the Period of 13th Five-year Plan (CIT&TCD20170324 to Wei Gao)the Key project at Central Government Level: The Ability Establishment of Sustainable Use for Valuable Chinese Medicine Resources (2060302 to Luqi Huang)
文摘Sterol C24-methyltransferase(SMT) plays multiple important roles in plant growth and development. SMT1, which belongs to the family of transferases and transforms cycloartenol into 24-methylene cycloartenol, is involved in the biosynthesis of 24-methyl sterols. Here, we report the cloning and characterization of a cDNA encoding a sterol C24-methyltransferase from Tripterygium wilfordii(Tw SMT1). Tw SMT1(Gen Bank access number KU885950) is a 1530 bp cDNA with a 1041 bp open reading frame predicted to encode a 346-amino acid, 38.62 k Da protein. The polypeptide encoded by the SMT1 cDNA was expressed and purified as a recombinant protein from Escherichia coli(E. coli) and showed SMT activity. The expression of Tw SMT1 was highly up-regulated in T. wilfordii cell suspension cultures treated with methyl jasmonate(Me JA). Tissue expression pattern analysis showed higher expression in the phellem layer compared to the other four organs(leaf, stem, xylem and phloem), which is about ten times that of the lowest expression in leaf. The results are meaningful for the study of sterolbiosynthesis of T. wilfordii and will further lay the foundations for the research in regulating both the content of other main compounds and growth and development of T. wilfordii.
基金supported by the China National Space Administration(CNSA)。
文摘The Hα imaging spectrograph(HIS) is the scientific payload of the first solar space mission, the Chinese Hα solar explorer(CHASE), supported by the China National Space Administration(CNSA). The CHASE/HIS achieves, for the first time in space, Hα spectroscopic observations with high spectral and temporal resolutions. Separate channels for the raster scanning mode(RSM) and continuum imaging mode(CIM) are integrated into one, and a highly integrated design is achieved through multiple folding of the optical path and ultra-light miniaturized components. The design of HIS implements a number of key technologies such as high-precision scanning of the optical field of view(FOV), high-precision integrated manufacturing inspection, a large-tolerance pre-filter window, and full-link solar radiation calibration. The HIS instrument has a pixel spectral resolution of 0.024 ? and can complete a full-Sun scanning within 46 s.
基金This work was funded by the Foundation of the EducationDepartment of Liaoning Province(UC201916 and LFW201901)The authors are very grateful to other people for their participation in this work.
文摘of main observation and conclusion Paraffin,as an excellent phase change material(PCM),is limited by the leakage problem and low thermal conductivity.In this research,a novel paraffin/neopentyl glycol dimethacrylate/boron nitride(paraffin/NPGDMA/BN)composite PCM was successfully prepared via a physical mixing process.NPGDMA in paraffin/NPGDMA/BN composite PCM was cured by UV light under the action of photo initiator,which can improve the shape stability to avoid the leakage of paraffin in the process of phase change.By comparing the leakage rate,latent heat,and thermal conductivity,the optimal mass ratio of paraffin and NPGDMA was selected to be 7:3.It was showed that the presence of 5 wt%BN led to increasing in thermal conductivity by up to 59%.The microstructure of the composite PCMs was characterized by SEM,FTIR,and XRD.The composite PCMs can be processed into a variety of shapes by using molds.The paraffin/NPGDMA/BN composite PCM exhibited a significantly improved shape stability and large phase change enthalpy of 123.0 J/g.The leakage rate of paraffin/NPGDMA/BN was much improved after being soaked with petroleum ether.
