Lots of field investigations have proven that layer-crack structure usually appears during the excavation process of deep rock or coal mass.To provide experimental data for studying the formation mechanism of layer-cr...Lots of field investigations have proven that layer-crack structure usually appears during the excavation process of deep rock or coal mass.To provide experimental data for studying the formation mechanism of layer-crack structure,this study researches the influence of lateral pressure on the mechanical behavior of different rock types.Four rock types have been tested and the formation mechanism of macro-fracture surface is analyzed.Results indicate that the brittleness and burst proneness of rock or coal material are stronger than that of gypsum material due to the different mineral compositions and structures.When the lateral pressure is less than 10%uniaxial strength,the peak stress and elastic modulus increase with the increase of lateral pressure;but when the lateral pressure is larger than 10%uniaxial strength,the two parameters decrease slightly or keep steady.This is because when the lateral pressure reaches a certain value,local failure will be formed during the process of applying lateral pressure.Under the condition of low lateral pressure,the failure of the specimen is dominated by the tensile mechanism;under the condition of relatively high lateral pressure,the area of the specimen close to the free surface is tensile splitting failure,and the area far from the free surface is shear failure.展开更多
Ionic liquids(ILs)have the advantages of low cost,eco-friendliness,abundant heteroatoms,excellent solubility,and coordinated ability with metal ions.These features make ILs a suitable precursor for fabricating metal s...Ionic liquids(ILs)have the advantages of low cost,eco-friendliness,abundant heteroatoms,excellent solubility,and coordinated ability with metal ions.These features make ILs a suitable precursor for fabricating metal singleatom catalysts(SACs).Herein,we prepared various metal single atoms anchored on ultrathin N-doped nanosheets(denoted as Cu_(1)/NC,Fe_(1)/NC,Co_(1)/NC,Ni_(1)/NC,and Pd_(1)/NC)by direct pyrolysis using ILs and g-C_(3)N_(4)nanosheets as templates.Taking benzene oxidation to phenol with H_(2)O_(2)as a model reaction to evaluate their catalytic performance and potential applications,Cu_(1)/NC calcined at 1000℃(denoted as Cu1/NC-1000)exhibits the highest activity with a turnover frequency of about 200 h^(-1)in the first 1 h at 60℃,which is better than that of most metal SACs reported in the literature.High benzene conversion of 82% with high phenol selectivity of 96% and excellent recyclability were achieved using the Cu_(1)/NC-1000 catalyst.This study provides an efficient general strategy for fabricating SACs using ILs for catalytic applications.展开更多
A duplex-phase Zr-2.5Nb alloy was treated by pulsed laser, followed by careful microstructural characterization using field emission gun scanning electron microscope and attached electron backscatter diffraction. Bene...A duplex-phase Zr-2.5Nb alloy was treated by pulsed laser, followed by careful microstructural characterization using field emission gun scanning electron microscope and attached electron backscatter diffraction. Beneath the modification zones with common uniform α-plate structures(UPS), a layer of unreported bimodal α-plate structures(BPS) featured by coarse(submicron)plates forming multiple cores surrounded by dense fine(nanoscale) plates was found. Presence of such BPS is attributed to non-equilibrium thermodynamic conditions induced by the pulsed laser treatments. Limited diffusion of Nb due to the short pulse during laser heating allows β phases with distinctly different Nb contents to be presented: Nb-enriched prior β films and Nb-depleted β phases, transforming into the fine and the coarse plates during cooling, respectively. Orientation analyses show that both types of plates in the BPS are aroused essentially from a single β orientation, suggesting epitaxial growth of the Nb-depletedβ phases from the preexisting β films.展开更多
基金Project(51904165)supported by the National Natural Science Foundation of ChinaProject(ZR2019QEE026)supported by the Shandong Provincial Natural Science Foundation,ChinaProject(ZR2019ZD13)supported by the Major Program of Shandong Provincial Natural Science Foundation,China。
文摘Lots of field investigations have proven that layer-crack structure usually appears during the excavation process of deep rock or coal mass.To provide experimental data for studying the formation mechanism of layer-crack structure,this study researches the influence of lateral pressure on the mechanical behavior of different rock types.Four rock types have been tested and the formation mechanism of macro-fracture surface is analyzed.Results indicate that the brittleness and burst proneness of rock or coal material are stronger than that of gypsum material due to the different mineral compositions and structures.When the lateral pressure is less than 10%uniaxial strength,the peak stress and elastic modulus increase with the increase of lateral pressure;but when the lateral pressure is larger than 10%uniaxial strength,the two parameters decrease slightly or keep steady.This is because when the lateral pressure reaches a certain value,local failure will be formed during the process of applying lateral pressure.Under the condition of low lateral pressure,the failure of the specimen is dominated by the tensile mechanism;under the condition of relatively high lateral pressure,the area of the specimen close to the free surface is tensile splitting failure,and the area far from the free surface is shear failure.
基金the financial support from the National Key R&D Program of China(2018YFA0208504 and 2018YFA0703503)the National Natural Science Foundation of China(21932006)the Youth Innovation Promotion Association of CAS(2017049).
文摘Ionic liquids(ILs)have the advantages of low cost,eco-friendliness,abundant heteroatoms,excellent solubility,and coordinated ability with metal ions.These features make ILs a suitable precursor for fabricating metal singleatom catalysts(SACs).Herein,we prepared various metal single atoms anchored on ultrathin N-doped nanosheets(denoted as Cu_(1)/NC,Fe_(1)/NC,Co_(1)/NC,Ni_(1)/NC,and Pd_(1)/NC)by direct pyrolysis using ILs and g-C_(3)N_(4)nanosheets as templates.Taking benzene oxidation to phenol with H_(2)O_(2)as a model reaction to evaluate their catalytic performance and potential applications,Cu_(1)/NC calcined at 1000℃(denoted as Cu1/NC-1000)exhibits the highest activity with a turnover frequency of about 200 h^(-1)in the first 1 h at 60℃,which is better than that of most metal SACs reported in the literature.High benzene conversion of 82% with high phenol selectivity of 96% and excellent recyclability were achieved using the Cu_(1)/NC-1000 catalyst.This study provides an efficient general strategy for fabricating SACs using ILs for catalytic applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.51401040&51401039)the Scientific and Technological Research Program of Chongqing Municipal Education Commission(Grant No.KJ1500901)+1 种基金the Natural Science Foundation of Hebei Province of China(Grant No.E2015203250)the Young Teachers Program of Yanshan University(Grant No.14LGA005)
文摘A duplex-phase Zr-2.5Nb alloy was treated by pulsed laser, followed by careful microstructural characterization using field emission gun scanning electron microscope and attached electron backscatter diffraction. Beneath the modification zones with common uniform α-plate structures(UPS), a layer of unreported bimodal α-plate structures(BPS) featured by coarse(submicron)plates forming multiple cores surrounded by dense fine(nanoscale) plates was found. Presence of such BPS is attributed to non-equilibrium thermodynamic conditions induced by the pulsed laser treatments. Limited diffusion of Nb due to the short pulse during laser heating allows β phases with distinctly different Nb contents to be presented: Nb-enriched prior β films and Nb-depleted β phases, transforming into the fine and the coarse plates during cooling, respectively. Orientation analyses show that both types of plates in the BPS are aroused essentially from a single β orientation, suggesting epitaxial growth of the Nb-depletedβ phases from the preexisting β films.
