Electrochemical CO_(2)conversion into value-added chemicals is a promising technology to solve the greenhouse effect and recycle chemical energy.However,the electrochemical CO_(2)reduction reaction(e-CO_(2)RR)is serio...Electrochemical CO_(2)conversion into value-added chemicals is a promising technology to solve the greenhouse effect and recycle chemical energy.However,the electrochemical CO_(2)reduction reaction(e-CO_(2)RR)is seriously compromised by weak CO_(2)adsorption and a rough CO_(2)activation process based on the chemical inertness of the CO_(2)molecule and the formed fragile metal–C/O bond.In this paper,we designed and fabricated Au particles embedded in ZrO_(2).The configuration of Au particles being of positive charge and ZrO_(2)with negative charge is induced and generated by metal–support interactions(MSIs).As a result,Au/ZrO_(2)@C presents a big difference in the CO_(2)conversion compared with the known work,affording a formate yield of 112.5μmol·cm^(−2)·h^(−1)at−1.1 V vs.reversible hydrogen electrode(RHE),and a max formate Faradaic efficiency of up to 94.1%at−0.9 V vs.RHE.This superior performance was attributed to the activated Au–ZrO_(2)interface to form the Au^(δ+)species.Both insitu Fourier transform infrared(FTIR)spectroscopy and theoretical calculations show that the MSIs configuration can be inclined to the*OCO intermediate generation on Au^(δ+)species activating CO_(2)molecules and then accelerate the formation of the*OCHO intermediate in e-CO_(2)RR,thereby favoring the CO_(2)conversion to formate.展开更多
In this study, a nonlinear model is presented for analysis of damage-cracking behavior in arch dams during strong earthquakes using different seismic input mechanisms. The nonlinear system includes a plastic-damage mo...In this study, a nonlinear model is presented for analysis of damage-cracking behavior in arch dams during strong earthquakes using different seismic input mechanisms. The nonlinear system includes a plastic-damage model for cyclic loading of concrete considering strain softening and a contact boundary model of contraction joint opening. Two different earthquake input mechanisms are used for comparison, including massless foundation input model and viscous-spring boundary model considering radiation damping due to infinite canyon. The results demonstrate that effects of seismic input mechanism and radiation damping on nonlinear response and damage-cracking of the dam are significant. Compared with the results of using massless foundation input model, the damage-cracking region and contraction joint opening are substantially reduced when using viscous-spring boundary model to take into account radiation damping. However, if the damping ratio of the dam is artificially increased to about 10%―15% for massless foundation input model, the joint opening and damage-cracking of the dam are comparable to the results obtained from the viscous-spring boundary model.展开更多
Drought is a major abiotic stress that limits plant growth and development.Adaptive mechanisms have evolved to mitigate drought stress,including the capacity to adjust water loss rate and to modify the morphology and ...Drought is a major abiotic stress that limits plant growth and development.Adaptive mechanisms have evolved to mitigate drought stress,including the capacity to adjust water loss rate and to modify the morphology and structure of the epidermis.Here,we show that the expression of CmNF-YB8,encoding a nuclear factor Y(NF-Y)B-type subunit,is lower under drought conditions in chrysanthemum(Chrysanthemum morifolium).Transgenicchrysanthemumlinesinwhich transcript levels of CmNF-YB8 were reduced by RNA interference(CmNF-YB8-RNAi)exhibited enhanced drought resistance relative to control lines,whereas lines overexpressing CmNF-YB8(CmNF-YB8-OX)were less tolerant to drought.Compared to wild type(WT),CmNF-YB8-RNAi plants showed reduced stomatal opening and a thicker epidermal cuticle that correlated with their water loss rate.We also identified genes involved in stomatal adjustment(CBLinteracting protein kinase 6,CmCIPK6)and cuticle biosynthesis(CmSHN3)that are more highly expressed in CmNF-YB8-RNAi lines than in WT,CmCIPK6 being a direct downstream target of CmNF-YB8.Virus-induced gene silencing of CmCIPK6 or CmSHN3 in the CmNFYB8-RNAi background abolished the effects of CmNF-YB8-RNAi on stomatal closure and cuticle deposition,respectively.CmNF-YB8 thus regulates CmCIPK6 and CmSHN3 expression to alter stomatal movement and cuticle thickness in the leaf epidermis,thereby affecting drought resistance.展开更多
A facile multi-component process for the synthesis of perfluoroalkylated quinolizine derivatives was achieved using various arylidenemalononitriles, pyridine, and methyl perfluoroalk-2-ynoates as starting materials. M...A facile multi-component process for the synthesis of perfluoroalkylated quinolizine derivatives was achieved using various arylidenemalononitriles, pyridine, and methyl perfluoroalk-2-ynoates as starting materials. Moderate yields were obtained under mild condition. The structures of perfluoroalkylated quinolizine derivatives were char- acterized by means of IH NMR, 13C NMR, 19F NMR, IR, LRMS and HRMS. Furthermore, the reaction mechanism was proposed.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB3500100)the National Natural Science Foundation of China(No.21805122)Industrial Support Plan Project of Colleges and Universities in Gansu Province(No.2021CYZC19).
文摘Electrochemical CO_(2)conversion into value-added chemicals is a promising technology to solve the greenhouse effect and recycle chemical energy.However,the electrochemical CO_(2)reduction reaction(e-CO_(2)RR)is seriously compromised by weak CO_(2)adsorption and a rough CO_(2)activation process based on the chemical inertness of the CO_(2)molecule and the formed fragile metal–C/O bond.In this paper,we designed and fabricated Au particles embedded in ZrO_(2).The configuration of Au particles being of positive charge and ZrO_(2)with negative charge is induced and generated by metal–support interactions(MSIs).As a result,Au/ZrO_(2)@C presents a big difference in the CO_(2)conversion compared with the known work,affording a formate yield of 112.5μmol·cm^(−2)·h^(−1)at−1.1 V vs.reversible hydrogen electrode(RHE),and a max formate Faradaic efficiency of up to 94.1%at−0.9 V vs.RHE.This superior performance was attributed to the activated Au–ZrO_(2)interface to form the Au^(δ+)species.Both insitu Fourier transform infrared(FTIR)spectroscopy and theoretical calculations show that the MSIs configuration can be inclined to the*OCO intermediate generation on Au^(δ+)species activating CO_(2)molecules and then accelerate the formation of the*OCHO intermediate in e-CO_(2)RR,thereby favoring the CO_(2)conversion to formate.
基金Supported by the National Natural Science Foundation of China (Grant Nos.90510018,90715041)the National Basic Research Program of China ("973") (Grant No.2002CB412709)
文摘In this study, a nonlinear model is presented for analysis of damage-cracking behavior in arch dams during strong earthquakes using different seismic input mechanisms. The nonlinear system includes a plastic-damage model for cyclic loading of concrete considering strain softening and a contact boundary model of contraction joint opening. Two different earthquake input mechanisms are used for comparison, including massless foundation input model and viscous-spring boundary model considering radiation damping due to infinite canyon. The results demonstrate that effects of seismic input mechanism and radiation damping on nonlinear response and damage-cracking of the dam are significant. Compared with the results of using massless foundation input model, the damage-cracking region and contraction joint opening are substantially reduced when using viscous-spring boundary model to take into account radiation damping. However, if the damping ratio of the dam is artificially increased to about 10%―15% for massless foundation input model, the joint opening and damage-cracking of the dam are comparable to the results obtained from the viscous-spring boundary model.
基金supported by the National Key Research and Development Program(2018YFD1000400)the National Natural Science Foundation of China(31572157 and31171990)+1 种基金the Beijing Municipal Science and Technology Project(Z191100008519007)the Construction of Beijing Science and Technology Innovation and Service Capacity in Top Subjects(CEFF-PXM2019_014207_000032)。
文摘Drought is a major abiotic stress that limits plant growth and development.Adaptive mechanisms have evolved to mitigate drought stress,including the capacity to adjust water loss rate and to modify the morphology and structure of the epidermis.Here,we show that the expression of CmNF-YB8,encoding a nuclear factor Y(NF-Y)B-type subunit,is lower under drought conditions in chrysanthemum(Chrysanthemum morifolium).Transgenicchrysanthemumlinesinwhich transcript levels of CmNF-YB8 were reduced by RNA interference(CmNF-YB8-RNAi)exhibited enhanced drought resistance relative to control lines,whereas lines overexpressing CmNF-YB8(CmNF-YB8-OX)were less tolerant to drought.Compared to wild type(WT),CmNF-YB8-RNAi plants showed reduced stomatal opening and a thicker epidermal cuticle that correlated with their water loss rate.We also identified genes involved in stomatal adjustment(CBLinteracting protein kinase 6,CmCIPK6)and cuticle biosynthesis(CmSHN3)that are more highly expressed in CmNF-YB8-RNAi lines than in WT,CmCIPK6 being a direct downstream target of CmNF-YB8.Virus-induced gene silencing of CmCIPK6 or CmSHN3 in the CmNFYB8-RNAi background abolished the effects of CmNF-YB8-RNAi on stomatal closure and cuticle deposition,respectively.CmNF-YB8 thus regulates CmCIPK6 and CmSHN3 expression to alter stomatal movement and cuticle thickness in the leaf epidermis,thereby affecting drought resistance.
文摘A facile multi-component process for the synthesis of perfluoroalkylated quinolizine derivatives was achieved using various arylidenemalononitriles, pyridine, and methyl perfluoroalk-2-ynoates as starting materials. Moderate yields were obtained under mild condition. The structures of perfluoroalkylated quinolizine derivatives were char- acterized by means of IH NMR, 13C NMR, 19F NMR, IR, LRMS and HRMS. Furthermore, the reaction mechanism was proposed.
