Production of hydrogen(H2) and oxygen(O2) through electrocatalytic water splitting is one of the sustainable,green and pivotal ways to accomplish the ever-increasing demands for renewable energy sources,but remains a ...Production of hydrogen(H2) and oxygen(O2) through electrocatalytic water splitting is one of the sustainable,green and pivotal ways to accomplish the ever-increasing demands for renewable energy sources,but remains a big challenge because of the uphill reaction during overall water splitting.Herein,we develop high-performance non-noble metal electrocatalysts for pH-universal water splitting,based on nickel/vanadium boride(NiVB) nanoparticles/reduced graphene oxide(rGO) hybrid(NiVB/rGO)through a facile chemical reduction approach under ambient condition.By virtue of more exposure to surface active sites,superior electron transfer capability and strong electronic coupling,the asprepared NiVB/rGO heterostructure needs pretty low overpotentials of 267 and 151 mV to deliver a current density of 10 mA cm^(-2) for oxygen evolution reaction(OER) and hydrogen evolution reaction(HER)respectively,with the corresponding Tafel slope of 44 and 88 mV dec^(-1) in 1.0 M KOH.Moreover,the NiVB/rGO electrocatalysts display a promising performance in a wide-pH conditions that require low overpotential of 310,353 and 489 mV to drive a current density of 10 mA cm^(-2) for OER under 0.5 M KOH,0.05 M H2SO4 and 1.0 M phosphate buffer solution(PBS) respectively,confirming the excellent electrocata lytic performance among state-of-the-art Ni-based electrocatalysts for overall water splitting.Therefore,the interfacial tuning based on incorporation of active heterostructure may pave a new route to develop bifunctional,cost-effective and efficient electrocatalyst systems for water splitting and H2 production.展开更多
The root system plays an important role in the growth and development of blueberry.The aim of this study was to assess the impacts of different fertilizers on the root growth and root–yield relationship of blueberry ...The root system plays an important role in the growth and development of blueberry.The aim of this study was to assess the impacts of different fertilizers on the root growth and root–yield relationship of blueberry to provide insight into the regulation of root growth and fruit yield by fertilizing from the perspective of the root system.Rabbiteye blueberry variety‘Britewell’as the test material,and six fertilizers,including BF,OR,CF,SF,HF,and RT were used in single-factor fertilization experiments to analyze the effects of different fertilizer treatments on the root morphology,root distribution,and fruit yield of blueberry.Fertilization overall increased the root length density and root surface area in most soil layers,and the RT treatment significantly increased the total root length density and total root surface area 98.6%and 98.5%,respectively,compared with a control lacking fertilizer.In addition,the effect of fertilization on the blueberry root system was mainly observed in the 0–20 cm layer.Fruit yield was positively correlated with total root length density and total root surface area,and negatively correlated with average root diameter.In summary,the SF and RT treatments increased the morphological indexes of the root system,particularly in the shallow soil layers,leading to an increase in blueberry fruit yield.展开更多
To evaluate the effects of nitrogen(N)and irrigation coupling on the soil N distribution,plant N utilization,and fruit yield of rabbiteye blueberries(Vaccinium virgatum),a field experiment was designed using two facto...To evaluate the effects of nitrogen(N)and irrigation coupling on the soil N distribution,plant N utilization,and fruit yield of rabbiteye blueberries(Vaccinium virgatum),a field experiment was designed using two factors(water and fertilizer application)with four levels of irrigation and three levels of fertilization,and a control.Under the different water and fertilizer combinations,N primarily accumulated in the leaves.Irrigation and N application within appropriate ranges(pure N≤29 g/plant and irrigation volume≤2.5 L/plant)significantly improved the blueberry fruit yield.Increases in water and N within these ranges promoted the effective accumulation of N in various organs and the absorption and utilization of N in the plants,which ultimately promoted blueberry yield.With increased N application rate,the nitrate N content of the 0–20 cm and 20–50 cm soil layers increased.With increased irrigation volume,the nitrate N content of the 0–20 cm soil layer decreased,while the nitrate content in the 20–50 cm soil layer increased.Low N and moderate water treatments resulted in high fruit yields and reduced nitrate N retention in the soil.Under these conditions,the economic input-output ratio was high and the soil N accumulation was low,and thus the economic and ecological benefits were maximized.展开更多
In this paper we study one-dimensional Fisher-Kolmogorov equation with density dependent non-linear diffusion. We choose the diffusion as a function of cell density such that it is high in highly cell populated areas ...In this paper we study one-dimensional Fisher-Kolmogorov equation with density dependent non-linear diffusion. We choose the diffusion as a function of cell density such that it is high in highly cell populated areas and it is small in the regions of fewer cells. The Fisher equation with non-linear diffusion is known as modified Fisher equation. We study the travelling wave solution of modified Fisher equation and find the approximation of minimum wave speed analytically, by using the eigenvalues of the stationary states, and numerically by using COMSOL (a commercial finite element solver). The results reveal that the minimum wave speed depends on the parameter values involved in the model. We observe that when diffusion is moderately non-linear, the eigenvalue method correctly predicts the minimum wave speed in our numerical calculations, but when diffusion is strongly non-linear the eigenvalues method gives the wrong answer.展开更多
Tissue engineering is a preeminent field which aims to regenerate or repair the functions of devastated or damaged organs or tissues due to some accident, disease or age related degeneration. This field provides immen...Tissue engineering is a preeminent field which aims to regenerate or repair the functions of devastated or damaged organs or tissues due to some accident, disease or age related degeneration. This field provides immense help in saving lives of thousands of patients. Tissues or organs are engineered within the patient’s body or in a laboratory, which is later implanted in the patient’s body. The important challenges for tissue engineers are: appropriate nutrients supply and optimum cell density with uniform distribution of cells in a final construct. Mathematical modeling is the best tool in order to understand the mechanism of cell proliferation and nutrient supply in a bioreactor. Mathematical models not only help to analyze potentially useful results but also enlighten the way of further research. In this work, a simple mathematical model of diffusive nutrient transport and non-linear cell proliferation in a bioreactor is developed. A cell seeded porous scaffold is kept in a bioreactor with a fixed nutrient supply. We model the consumption and transport of nutrients by reaction-diffusion equation and cell proliferation by Fisher Kolmogorove equation. Nutrient delivery to the cell seeded scaffold is purely due to diffusion. The model is solved numerically by commercial finite element solver COMSOL. The results show that all types of constructs, if nutrient supply depends on diffusion, will produce cell proliferated regions near nutrient supply. The results are presented for uniform and non-uniform initial cell seeding strategies. It is also observed that cell proliferation is insensitive to the initial seeding strategy.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.21771021,21822501,21720303,and 22061130206)the Beijing Municipal Natural Science Foundation(JQ20003)+5 种基金the Newton Advanced Fellowship award(NAF\R1\201285)the Fok Ying-Tong Education Foundation(Grant No.171008)the Beijing Nova Program(Grant No.xx2018115)the State Key Laboratory of Rare Earth Resources UtilizationChangchun Institute of Applied Chemistry,CAS(RERU2019005)the Fundamental Research Funds for the Central Universities and the Measurements Fund of Beijing Normal University。
文摘Production of hydrogen(H2) and oxygen(O2) through electrocatalytic water splitting is one of the sustainable,green and pivotal ways to accomplish the ever-increasing demands for renewable energy sources,but remains a big challenge because of the uphill reaction during overall water splitting.Herein,we develop high-performance non-noble metal electrocatalysts for pH-universal water splitting,based on nickel/vanadium boride(NiVB) nanoparticles/reduced graphene oxide(rGO) hybrid(NiVB/rGO)through a facile chemical reduction approach under ambient condition.By virtue of more exposure to surface active sites,superior electron transfer capability and strong electronic coupling,the asprepared NiVB/rGO heterostructure needs pretty low overpotentials of 267 and 151 mV to deliver a current density of 10 mA cm^(-2) for oxygen evolution reaction(OER) and hydrogen evolution reaction(HER)respectively,with the corresponding Tafel slope of 44 and 88 mV dec^(-1) in 1.0 M KOH.Moreover,the NiVB/rGO electrocatalysts display a promising performance in a wide-pH conditions that require low overpotential of 310,353 and 489 mV to drive a current density of 10 mA cm^(-2) for OER under 0.5 M KOH,0.05 M H2SO4 and 1.0 M phosphate buffer solution(PBS) respectively,confirming the excellent electrocata lytic performance among state-of-the-art Ni-based electrocatalysts for overall water splitting.Therefore,the interfacial tuning based on incorporation of active heterostructure may pave a new route to develop bifunctional,cost-effective and efficient electrocatalyst systems for water splitting and H2 production.
基金the National Natural Science Foundation of China,Grant No.“31760205”.
文摘The root system plays an important role in the growth and development of blueberry.The aim of this study was to assess the impacts of different fertilizers on the root growth and root–yield relationship of blueberry to provide insight into the regulation of root growth and fruit yield by fertilizing from the perspective of the root system.Rabbiteye blueberry variety‘Britewell’as the test material,and six fertilizers,including BF,OR,CF,SF,HF,and RT were used in single-factor fertilization experiments to analyze the effects of different fertilizer treatments on the root morphology,root distribution,and fruit yield of blueberry.Fertilization overall increased the root length density and root surface area in most soil layers,and the RT treatment significantly increased the total root length density and total root surface area 98.6%and 98.5%,respectively,compared with a control lacking fertilizer.In addition,the effect of fertilization on the blueberry root system was mainly observed in the 0–20 cm layer.Fruit yield was positively correlated with total root length density and total root surface area,and negatively correlated with average root diameter.In summary,the SF and RT treatments increased the morphological indexes of the root system,particularly in the shallow soil layers,leading to an increase in blueberry fruit yield.
基金funded by the National Natural Science Foundation of China(NSFC 31260192)the Major Projects in Guizhou Province(SY[2015]6032-2)。
文摘To evaluate the effects of nitrogen(N)and irrigation coupling on the soil N distribution,plant N utilization,and fruit yield of rabbiteye blueberries(Vaccinium virgatum),a field experiment was designed using two factors(water and fertilizer application)with four levels of irrigation and three levels of fertilization,and a control.Under the different water and fertilizer combinations,N primarily accumulated in the leaves.Irrigation and N application within appropriate ranges(pure N≤29 g/plant and irrigation volume≤2.5 L/plant)significantly improved the blueberry fruit yield.Increases in water and N within these ranges promoted the effective accumulation of N in various organs and the absorption and utilization of N in the plants,which ultimately promoted blueberry yield.With increased N application rate,the nitrate N content of the 0–20 cm and 20–50 cm soil layers increased.With increased irrigation volume,the nitrate N content of the 0–20 cm soil layer decreased,while the nitrate content in the 20–50 cm soil layer increased.Low N and moderate water treatments resulted in high fruit yields and reduced nitrate N retention in the soil.Under these conditions,the economic input-output ratio was high and the soil N accumulation was low,and thus the economic and ecological benefits were maximized.
文摘In this paper we study one-dimensional Fisher-Kolmogorov equation with density dependent non-linear diffusion. We choose the diffusion as a function of cell density such that it is high in highly cell populated areas and it is small in the regions of fewer cells. The Fisher equation with non-linear diffusion is known as modified Fisher equation. We study the travelling wave solution of modified Fisher equation and find the approximation of minimum wave speed analytically, by using the eigenvalues of the stationary states, and numerically by using COMSOL (a commercial finite element solver). The results reveal that the minimum wave speed depends on the parameter values involved in the model. We observe that when diffusion is moderately non-linear, the eigenvalue method correctly predicts the minimum wave speed in our numerical calculations, but when diffusion is strongly non-linear the eigenvalues method gives the wrong answer.
文摘Tissue engineering is a preeminent field which aims to regenerate or repair the functions of devastated or damaged organs or tissues due to some accident, disease or age related degeneration. This field provides immense help in saving lives of thousands of patients. Tissues or organs are engineered within the patient’s body or in a laboratory, which is later implanted in the patient’s body. The important challenges for tissue engineers are: appropriate nutrients supply and optimum cell density with uniform distribution of cells in a final construct. Mathematical modeling is the best tool in order to understand the mechanism of cell proliferation and nutrient supply in a bioreactor. Mathematical models not only help to analyze potentially useful results but also enlighten the way of further research. In this work, a simple mathematical model of diffusive nutrient transport and non-linear cell proliferation in a bioreactor is developed. A cell seeded porous scaffold is kept in a bioreactor with a fixed nutrient supply. We model the consumption and transport of nutrients by reaction-diffusion equation and cell proliferation by Fisher Kolmogorove equation. Nutrient delivery to the cell seeded scaffold is purely due to diffusion. The model is solved numerically by commercial finite element solver COMSOL. The results show that all types of constructs, if nutrient supply depends on diffusion, will produce cell proliferated regions near nutrient supply. The results are presented for uniform and non-uniform initial cell seeding strategies. It is also observed that cell proliferation is insensitive to the initial seeding strategy.
