An ecosystem-based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamic and sediment model. As both phosphorus and...An ecosystem-based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamic and sediment model. As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both there nutrient cycles each using five variables, namely, dissolved inorganic nutri- ent, detritic organic matter, benthic matter, phytoplankton and zooplankton.展开更多
The classical 1-D vertical advection-diffusion model was improved in this work. The main advantages of the improved model over the previous one are: 1) The applicable condition of the 1-D model is made clear in the im...The classical 1-D vertical advection-diffusion model was improved in this work. The main advantages of the improved model over the previous one are: 1) The applicable condition of the 1-D model is made clear in the improved model, in that it is substantively applicable only to a vertical domain on which two end-member water masses are mixing. 2) The substitution of parameter f(z) in the equation of the classical 1-D model with end-member fraction f 1z makes the model more precisely and easily solved. 3) All the terms in the improved model equation have specific physical meanings, which makes the model easily understood. Practical application of the improved model to predict the vertical profiles of dissolved oxygen and micronutrients in abyssal ocean water of the North Pacific proved that the improvement of the 1-D advection-diffusion model is successful and practicable.展开更多
Rational design of highly active transition-metal phosphides for electrocatalyzing overall water splitting in a wide pH range assisted by first-principle calculations can efficiently save the developing cost and hence...Rational design of highly active transition-metal phosphides for electrocatalyzing overall water splitting in a wide pH range assisted by first-principle calculations can efficiently save the developing cost and hence is quite attractive.Under the guidance of density-functional theory(DFT)calculations that the introduction of dopants(Fe,Mn,and Ni)into CoP could promote the hydrogen evolution reaction(HER)performances,a series of binder-free CoM_(x)P/carbon cloth(CC;M=Fe,Mn,and Ni;x=0,0.05,0.2,0.5,and 1)were fabricated.Both experimental measurements and DFT calculations confirm the electronic modulation of dopants.DFT calculations further reveal that the modulated electronic structure promotes the electronic conductivity,favors the adsorption of key species,and consequently promotes the electrochemical performances.As predicted,the bimetallic phosphides demonstrate excellent HER performances in alkaline,acidic,and alkaline simulated seawater solutions and also deliver excellent oxygen evolution reaction(OER)performances,overwhelming the commercial RuO_(2).Benefiting from the modulated electronic structure and the hierarchical structure with massive CoFe0.05P zero-dimensional(0D)quantum dots anchored on two-dimensional(2D)N-doped porous carbon,CoFe0.05P delivered the best HER in four kinds of electrolytes(ƞ10 of 73 mV in an alkaline simulated seawater solution)and OER in two kinds of electrolytes(ƞ10 of 264 mV in an alkaline solution)with excellent stability of 45 h in the alkaline solution.The assembled CoFe0.05P/CC//CoFe0.05P/CC with the electrodes folded by 180°can still maintain a low cell potential of 1.62 V at 10 mA·cm^(−2).This work proves the feasibility of the reported rational design strategy of developing efficient electrocatalysts for overall water splitting in a wide pH range.展开更多
Ferromagnetism in undoped and cobalt-doped high-k HfO2 films was investigated. No ferromagnetism was observed in stoichiometric HfO2 films, but we observed weak ferromagnetism in highly oxygen-deficient HfO2 films. Un...Ferromagnetism in undoped and cobalt-doped high-k HfO2 films was investigated. No ferromagnetism was observed in stoichiometric HfO2 films, but we observed weak ferromagnetism in highly oxygen-deficient HfO2 films. Undoped and cobalt doped films were treated by alternate annealing in vacuum and oxygen atmospheres. From the experiments, both the lack of oxygen vacancies and the increase of oxygen species in bulk （e.g. interstitial oxygen） will degrade the magnetic ordering. Additionally, it is believed that cobalt doping has no obvious relationship with the observed intrinsic do magnetism.展开更多
基金The present study was supported by the Pearl River Estuary Pollution Project funded by the Hong Kong Government/Hong Kong Jock
文摘An ecosystem-based water quality model was designed to estimate the biochemical reaction of nutrient and dissolved oxygen in conjunction with a three-dimensional hydrodynamic and sediment model. As both phosphorus and nitrogen successively limit phytoplankton growth in many estuaries, the model simulates both there nutrient cycles each using five variables, namely, dissolved inorganic nutri- ent, detritic organic matter, benthic matter, phytoplankton and zooplankton.
文摘The classical 1-D vertical advection-diffusion model was improved in this work. The main advantages of the improved model over the previous one are: 1) The applicable condition of the 1-D model is made clear in the improved model, in that it is substantively applicable only to a vertical domain on which two end-member water masses are mixing. 2) The substitution of parameter f(z) in the equation of the classical 1-D model with end-member fraction f 1z makes the model more precisely and easily solved. 3) All the terms in the improved model equation have specific physical meanings, which makes the model easily understood. Practical application of the improved model to predict the vertical profiles of dissolved oxygen and micronutrients in abyssal ocean water of the North Pacific proved that the improvement of the 1-D advection-diffusion model is successful and practicable.
基金supported by the National Key Research and Development Program of China(No.2019YFB1311605)the National Natural Science Foundation of China(No.21703137)the Shanghai Sailing Program(No.20YF1416100).
文摘Rational design of highly active transition-metal phosphides for electrocatalyzing overall water splitting in a wide pH range assisted by first-principle calculations can efficiently save the developing cost and hence is quite attractive.Under the guidance of density-functional theory(DFT)calculations that the introduction of dopants(Fe,Mn,and Ni)into CoP could promote the hydrogen evolution reaction(HER)performances,a series of binder-free CoM_(x)P/carbon cloth(CC;M=Fe,Mn,and Ni;x=0,0.05,0.2,0.5,and 1)were fabricated.Both experimental measurements and DFT calculations confirm the electronic modulation of dopants.DFT calculations further reveal that the modulated electronic structure promotes the electronic conductivity,favors the adsorption of key species,and consequently promotes the electrochemical performances.As predicted,the bimetallic phosphides demonstrate excellent HER performances in alkaline,acidic,and alkaline simulated seawater solutions and also deliver excellent oxygen evolution reaction(OER)performances,overwhelming the commercial RuO_(2).Benefiting from the modulated electronic structure and the hierarchical structure with massive CoFe0.05P zero-dimensional(0D)quantum dots anchored on two-dimensional(2D)N-doped porous carbon,CoFe0.05P delivered the best HER in four kinds of electrolytes(ƞ10 of 73 mV in an alkaline simulated seawater solution)and OER in two kinds of electrolytes(ƞ10 of 264 mV in an alkaline solution)with excellent stability of 45 h in the alkaline solution.The assembled CoFe0.05P/CC//CoFe0.05P/CC with the electrodes folded by 180°can still maintain a low cell potential of 1.62 V at 10 mA·cm^(−2).This work proves the feasibility of the reported rational design strategy of developing efficient electrocatalysts for overall water splitting in a wide pH range.
基金supported by the Postdoctoral Science Foundation of China(No.20080431176)the Special Fund for Postdoctoral Innovative Project of Shandong Province(No.200702027)the Doctoral Fund of Ministry of Education of China(No.200804221006)
文摘Ferromagnetism in undoped and cobalt-doped high-k HfO2 films was investigated. No ferromagnetism was observed in stoichiometric HfO2 films, but we observed weak ferromagnetism in highly oxygen-deficient HfO2 films. Undoped and cobalt doped films were treated by alternate annealing in vacuum and oxygen atmospheres. From the experiments, both the lack of oxygen vacancies and the increase of oxygen species in bulk （e.g. interstitial oxygen） will degrade the magnetic ordering. Additionally, it is believed that cobalt doping has no obvious relationship with the observed intrinsic do magnetism.
