In view of the shortage of using traditional methods to monitor chlorophyll content, hyperspectral technology was used to estimate the chlorophyll content of grape leaves rapidly, accurately and non-destructively. Bas...In view of the shortage of using traditional methods to monitor chlorophyll content, hyperspectral technology was used to estimate the chlorophyll content of grape leaves rapidly, accurately and non-destructively. Based on the data of hyperspectral reflectivity and SPAD value of grape leaves collected from Wanjishan grape planting base in Tai an, the correlations of SPAD value with the original spectral reflectivity of grape leaves and its first derivative were analyzed to select sensitive bands, and an estimation model of chlorophyll content in grape leaves based on hyperspectral reflectivity was established. The best model was SPAD = 59.352＋ 44 836.313 R 601 .展开更多
Developing low-cost,efficient,and stable non-precious-metal electrocatalysts with controlled crystal structure,morphology and compositions are highly desirable for hydrogen and oxygen evolution reactions.Herein,a seri...Developing low-cost,efficient,and stable non-precious-metal electrocatalysts with controlled crystal structure,morphology and compositions are highly desirable for hydrogen and oxygen evolution reactions.Herein,a series of phosphorus-doped Fe_(7)S_(8)nanowires integrated within carbon(P-Fe_(7)S_(8)@C)are rationally synthesized via a one-step phosphorization of one-dimensional(1D)Fe-based organicinorganic nanowires.The as-obtained P-Fe_(7)S_(8)@C catalysts with modified electronic configurations present typical porous structure,providing plentiful active sites for rapid reaction kinetics.Density functional calculations demonstrate that the doping Fe_(7)S_(8)with P can effectively enhance the electron density of Fe_(7)S_(8)around the Fermi level and weaken the Fe-H bonding,leading to the decrease of adsorption free energy barrier on active sites.As a result,the optimal catalyst of P-Fe_(7)S_(8)-600@C exhibits a relatively low overpotential of 136 mV for hydrogen evolution reaction(HER)to reach the current density of 10 mA/cm^(2),and a significantly low overpotential of 210 mV for oxygen evolution reaction(OER)at 20 mA/cm^(2)in alkaline media.The work presented here may pave the way to design and synthesis of other prominent Fe-based catalysts for water splitting via electronic regulation.展开更多
Biological experiments clarify that p53-Mdm2 module is the core of tumor network and p53 oscillation plays an important role in determining the tumor cell fate.In this paper,we investigate the effect of time delay on ...Biological experiments clarify that p53-Mdm2 module is the core of tumor network and p53 oscillation plays an important role in determining the tumor cell fate.In this paper,we investigate the effect of time delay on the oscillatory behavior induced by Hopf bifurcation in p53-Mdm2 system.First,the stability of the unique positive equilibriurm point and the existence of Hopf bifurcation are investigated by using the time delay as the bifurcation parameter and by applying the bifurcation theory.Second,the explicit criteria determining the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are developed based on the normal form theory and the center manifold theorem.In addition,the combination of numerical simulation results and theoretical calculation results indicates that time delays in p53-Mdm2 system are critical for p53 oscillations.The results may help us to better understand the biological functions of p53 pathway and provide clues for treatment of cancer.展开更多
基金Supported by Innovation Engineering Project of Shandong Academy of Agricultural Sciences(CXGC2017B04)Major Research and Development Plan Program of Shandong Province,China(2016CYJS03A01-1)National Research and Development Program of China(2017YFD0301004)
文摘In view of the shortage of using traditional methods to monitor chlorophyll content, hyperspectral technology was used to estimate the chlorophyll content of grape leaves rapidly, accurately and non-destructively. Based on the data of hyperspectral reflectivity and SPAD value of grape leaves collected from Wanjishan grape planting base in Tai an, the correlations of SPAD value with the original spectral reflectivity of grape leaves and its first derivative were analyzed to select sensitive bands, and an estimation model of chlorophyll content in grape leaves based on hyperspectral reflectivity was established. The best model was SPAD = 59.352＋ 44 836.313 R 601 .
基金the National Natural Science Foundation of China(Nos.21601120 and 21805181)the Science and Technology Commission of Shanghai Municipality(Nos.17ZR1410500 and 19ZR1418100)+1 种基金the High Performance Computing Center of Shanghai UniversityShanghai Engineering Research Center of Intelligent Computing System(No.19DZ2252600)for providing the computing resources and technical support。
文摘Developing low-cost,efficient,and stable non-precious-metal electrocatalysts with controlled crystal structure,morphology and compositions are highly desirable for hydrogen and oxygen evolution reactions.Herein,a series of phosphorus-doped Fe_(7)S_(8)nanowires integrated within carbon(P-Fe_(7)S_(8)@C)are rationally synthesized via a one-step phosphorization of one-dimensional(1D)Fe-based organicinorganic nanowires.The as-obtained P-Fe_(7)S_(8)@C catalysts with modified electronic configurations present typical porous structure,providing plentiful active sites for rapid reaction kinetics.Density functional calculations demonstrate that the doping Fe_(7)S_(8)with P can effectively enhance the electron density of Fe_(7)S_(8)around the Fermi level and weaken the Fe-H bonding,leading to the decrease of adsorption free energy barrier on active sites.As a result,the optimal catalyst of P-Fe_(7)S_(8)-600@C exhibits a relatively low overpotential of 136 mV for hydrogen evolution reaction(HER)to reach the current density of 10 mA/cm^(2),and a significantly low overpotential of 210 mV for oxygen evolution reaction(OER)at 20 mA/cm^(2)in alkaline media.The work presented here may pave the way to design and synthesis of other prominent Fe-based catalysts for water splitting via electronic regulation.
基金The authors express gratitude to the anony imnous referee for his/her helpful Sug-gestions and the partial supports of the National Natural Science Foundations of China(Grants Nos.11762022,11562021 and 11572278)the youth academic and technical leaders of Yunnan Province(No.2019HB015).
文摘Biological experiments clarify that p53-Mdm2 module is the core of tumor network and p53 oscillation plays an important role in determining the tumor cell fate.In this paper,we investigate the effect of time delay on the oscillatory behavior induced by Hopf bifurcation in p53-Mdm2 system.First,the stability of the unique positive equilibriurm point and the existence of Hopf bifurcation are investigated by using the time delay as the bifurcation parameter and by applying the bifurcation theory.Second,the explicit criteria determining the direction of Hopf bifurcation and the stability of bifurcating periodic solutions are developed based on the normal form theory and the center manifold theorem.In addition,the combination of numerical simulation results and theoretical calculation results indicates that time delays in p53-Mdm2 system are critical for p53 oscillations.The results may help us to better understand the biological functions of p53 pathway and provide clues for treatment of cancer.
