The sediment content of the Yellow River is resulted from the interactions of natural, economic, and social factors, so it includes some evolutive information of the Yellow River Basin system. Sediment contents from 1...The sediment content of the Yellow River is resulted from the interactions of natural, economic, and social factors, so it includes some evolutive information of the Yellow River Basin system. Sediment contents from 1952 to 2007 on Toudaoguai, Tongguan, Huayuankou and Lijin sections along the river are chosen as the study time series, and correlation dimensions （D2）, Kolmogorov entropies （K2）, and Hurst indexes （H） of the time series were calculated. Correlation dimensions on Toudaoguai, Tongguan, Huayuankou, and Lijin sections are 3.24, 5.69, 6.57 and 7.34 respectively, and the Kolmogorov entropies are 0.13, 0.37, 0.40 and 0.38 respectively, which indicates that the systems controlled by different sections along the Yellow River are chaotic systems and the chaotic degrees increase gradually from the upper to lower section. The average predictable period of the sediment contents is 8 years on Toudaoguai section and 3 years on the other sections with the reciprocals of the Kolmogorov entropies. The more obvious the chaotic degree is, the shorter the average predictable period is. Hurst indexes on the sections are above 0.5, with the maximum of 0.86 on Tongguan section and the minimum of 0.68 on Toudaoguai section, which indicates that the time series have persistent trends in the average predictable period. Eight state variables and two control parameters are necessary to construct the dynamic model of the Yellow River Basin system.展开更多
El Niño-Southern Oscillation(ENSO)affects the changes in ocean physical elements in Taiwan Strait(TWS)primarily by regulating the strength of the East Asian Winter Monsoon(EAWM)and the intrusion of the Kuroshio.A...El Niño-Southern Oscillation(ENSO)affects the changes in ocean physical elements in Taiwan Strait(TWS)primarily by regulating the strength of the East Asian Winter Monsoon(EAWM)and the intrusion of the Kuroshio.Additionally,the fluctuating impact between nutrient-poor seawater with high dissolved inorganic carbon(DIC)that infiltrates owing to the Kuroshio during El Niño phases and nutrient-rich seawater with low DIC from the South China Sea(SCS)carried by the EAWM during La Niña phases determines the nutrient content in TWS,thereby sculpting appropriate or unsuitable biochemical environment.In this study,based on high-resolution sea-surface partial pressure of carbon dioxide(pCO_(2))data,we investigate the relationship between pCO_(2)level of TWS and ENSO events in winter.The physical mechanisms affecting the anomalous distribution of pCO_(2)level during ENSO are also explored.Stepwise regression was employed to identify the optimal influencing factors for modeling pCO_(2).Results indicate a significant positive correlation between Niño3.4 index and pCO_(2),which is significantly influenced by factors such as sea-surface temperature(SST),chlorophyll-a(Chl a),and DIC.These are related to the anomalously strong Kuroshio intrusion and weaker EAWM during El Niño years.It brings a large amount of high SST water with low nutrient concentration and high DIC,which is detrimental to CO_(2)dissolution and phytoplankton growth over the TWS,leading to an increase in pCO_(2).Conversely,pCO_(2)level is significantly low under the influence of SCS seawater during La Niña years.Based on the characterization of the pCO_(2)level response to ENSO,the carbon balance at TWS can be explored.展开更多
By integrating photocatalytic H_(2)O_(2) production with furfuryl alcohol(FAL)oxidation,this coupled process establishes an atom-economical pathway for sustainable chemical synthesis,simultaneously achieving energy st...By integrating photocatalytic H_(2)O_(2) production with furfuryl alcohol(FAL)oxidation,this coupled process establishes an atom-economical pathway for sustainable chemical synthesis,simultaneously achieving energy storage and biomass valorization.This study introduces a meticulously engineered MOF@MOF hierarchical photocatalytic architecture,specifically the PCN-134@MOF-525(PM-X series)composite,designed for synergistic catalysis of these processes.By strategically integrating two distinct MOF materials,we circumvent the limitations of single-component systems,such as facile charge carrier recombination,and establish a redox dualactive site catalytic system.This rational design transcends simple additivity,yielding emergent catalytic behaviors driven by precise control over interfacial electric fields and dynamic structural modulation.The resultant hierarchical organization enhances light harvesting,promotes efficient charge separation,and accelerates charge transfer kinetics.Mechanistic insights,derived from photoelectrochemical,spectroscopic,and in-situ IR analyses,reveal a synergistic interplay that suppresses electron-hole recombination and spatially segregates redox processes.PM-3 demonstrates a significant enhancement in catalytic efficiency(the highest value reported),exhibiting a 4.5-fold increase in both H_(2)O_(2) production and FAL oxidation rates compared to the individual MOF components,achieving near-quantitative FAL conversion and exceptional selectivity.This work provides a potent design blueprint,emphasizing interfacial engineering and structural synergy for unprecedented efficiency and selectivity in sustainable chemical transformations.展开更多
Anion exchange membrane electrolysis (AEMWE) is currently a promising technology to produce hydrogen from water. Developing the highly intrinsic activity of electrodes is extremely important. In this paper, nitrogen v...Anion exchange membrane electrolysis (AEMWE) is currently a promising technology to produce hydrogen from water. Developing the highly intrinsic activity of electrodes is extremely important. In this paper, nitrogen vacancies-rich cobalt nitride (Co_(4)N-VN) is used as the anode catalyst of the urea oxidation reaction (UOR) and its loading Pt (Pt@Co_(4)N-VN) acted as the cathode of hydrogen evolution reaction (HER). The introduction of N-vacancies gained the electron-deficient Co_(4)N more favorable for the UOR process. Meanwhile, the electron transfer between the Co_(4)N-VN carrier and Pt can enhance the intrinsic HER activity of loaded Pt. Specifically, in the 0.33 M urea and 1.0 M KOH electrolyte, the UOR potential of CO_(4)N-VN is only 1.58 V at the current density of 300.0 mA cm^(-2), which is much lower than that of Co_(4) N and Co_(3)O_(4). At the same time, the HER overpotential at 1.0 M KOH and 300.0 mA cm^(-2) is only 120.0 mV, lower than 20 wt% Pt/C. By measuring the bode phase diagram, the presence of N-vacancies can accelerate the electron transfer rate of catalysts to improve the UOR and HER electrocatalytic activity. The overall water-splitting device featuring Pt@Co_(4)N-VN||Co_(4)N-VN electrodes achieves a voltage of 2.99 V at a current density of 300.0 mA cm^(-2).展开更多
There is a need for more focus in understanding the economic benefits of Climate-Smart Agriculture(CSA)interventions,particularly in sub-Saharan Africa,where extreme climate events are significantly affecting agricult...There is a need for more focus in understanding the economic benefits of Climate-Smart Agriculture(CSA)interventions,particularly in sub-Saharan Africa,where extreme climate events are significantly affecting agriculture and rural livelihoods.This study used the Net Present Value(NPV),Internal Rate of Return(IRR),Benefit-Cost Ratio(BCR),and payback period to evaluate the economic viability of the adopted CSA interventions in the three villages(Doggoh,Jeffiri,and Wulling)of the dryland farming systems of northern Ghana,where CSA interventions were mostly practiced.Data were collected from 161 farm households by the questionnaire survey.The results showed that CSA interventions including livestock-crop integration,mixed cropping,crop rotation,nutrient integration,and tie ridging enhanced crop yield and the household income of smallholder farmers.The five CSA interventions selected by smallholders were in the following order of priority:livestock-crop integration(BCR=2.87),mixed cropping(BCR=2.54),crop rotation(BCR=2.24),nutrient integration(BCR=1.98),and tie ridging(BCR=1.42).Results further showed that livestock-crop integration was the most profitable CSA intervention even under a pessimistic assumption with a long payback period of 5.00 a.Moreover,this study indicated that the implementation of CSA interventions,on average,was relatively profitable and had a nominal financial risk for smallholder farmers.Understanding the economic viability of CSA interventions will help in decision-making process toward selecting the right CSA interventions for resilience development.展开更多
基金National Natural Science Foundation of China, No.40601105 Key Project of Science and Technology of Henan Province, No.0721021500
文摘The sediment content of the Yellow River is resulted from the interactions of natural, economic, and social factors, so it includes some evolutive information of the Yellow River Basin system. Sediment contents from 1952 to 2007 on Toudaoguai, Tongguan, Huayuankou and Lijin sections along the river are chosen as the study time series, and correlation dimensions （D2）, Kolmogorov entropies （K2）, and Hurst indexes （H） of the time series were calculated. Correlation dimensions on Toudaoguai, Tongguan, Huayuankou, and Lijin sections are 3.24, 5.69, 6.57 and 7.34 respectively, and the Kolmogorov entropies are 0.13, 0.37, 0.40 and 0.38 respectively, which indicates that the systems controlled by different sections along the Yellow River are chaotic systems and the chaotic degrees increase gradually from the upper to lower section. The average predictable period of the sediment contents is 8 years on Toudaoguai section and 3 years on the other sections with the reciprocals of the Kolmogorov entropies. The more obvious the chaotic degree is, the shorter the average predictable period is. Hurst indexes on the sections are above 0.5, with the maximum of 0.86 on Tongguan section and the minimum of 0.68 on Toudaoguai section, which indicates that the time series have persistent trends in the average predictable period. Eight state variables and two control parameters are necessary to construct the dynamic model of the Yellow River Basin system.
基金The Key R&D Project of Zhejiang Province under contract No.2023C03120the General Scientific Research Project of Zhejiang Province under contract No.Y202353957the National Natural Science Foundation of China under contract No.42106017.
文摘El Niño-Southern Oscillation(ENSO)affects the changes in ocean physical elements in Taiwan Strait(TWS)primarily by regulating the strength of the East Asian Winter Monsoon(EAWM)and the intrusion of the Kuroshio.Additionally,the fluctuating impact between nutrient-poor seawater with high dissolved inorganic carbon(DIC)that infiltrates owing to the Kuroshio during El Niño phases and nutrient-rich seawater with low DIC from the South China Sea(SCS)carried by the EAWM during La Niña phases determines the nutrient content in TWS,thereby sculpting appropriate or unsuitable biochemical environment.In this study,based on high-resolution sea-surface partial pressure of carbon dioxide(pCO_(2))data,we investigate the relationship between pCO_(2)level of TWS and ENSO events in winter.The physical mechanisms affecting the anomalous distribution of pCO_(2)level during ENSO are also explored.Stepwise regression was employed to identify the optimal influencing factors for modeling pCO_(2).Results indicate a significant positive correlation between Niño3.4 index and pCO_(2),which is significantly influenced by factors such as sea-surface temperature(SST),chlorophyll-a(Chl a),and DIC.These are related to the anomalously strong Kuroshio intrusion and weaker EAWM during El Niño years.It brings a large amount of high SST water with low nutrient concentration and high DIC,which is detrimental to CO_(2)dissolution and phytoplankton growth over the TWS,leading to an increase in pCO_(2).Conversely,pCO_(2)level is significantly low under the influence of SCS seawater during La Niña years.Based on the characterization of the pCO_(2)level response to ENSO,the carbon balance at TWS can be explored.
基金supported by National Natural Science Foundation of China(22378219)Project ZR2023QB173 supported by Shandong Provincial Natural Science Foundation and Postdoctoral Application Project of Qingdao(QHBSH20230102024)Prof.H.Tang gratefully acknowledges financial support from Taishan Youth Scholar Program of Shandong Province.
文摘By integrating photocatalytic H_(2)O_(2) production with furfuryl alcohol(FAL)oxidation,this coupled process establishes an atom-economical pathway for sustainable chemical synthesis,simultaneously achieving energy storage and biomass valorization.This study introduces a meticulously engineered MOF@MOF hierarchical photocatalytic architecture,specifically the PCN-134@MOF-525(PM-X series)composite,designed for synergistic catalysis of these processes.By strategically integrating two distinct MOF materials,we circumvent the limitations of single-component systems,such as facile charge carrier recombination,and establish a redox dualactive site catalytic system.This rational design transcends simple additivity,yielding emergent catalytic behaviors driven by precise control over interfacial electric fields and dynamic structural modulation.The resultant hierarchical organization enhances light harvesting,promotes efficient charge separation,and accelerates charge transfer kinetics.Mechanistic insights,derived from photoelectrochemical,spectroscopic,and in-situ IR analyses,reveal a synergistic interplay that suppresses electron-hole recombination and spatially segregates redox processes.PM-3 demonstrates a significant enhancement in catalytic efficiency(the highest value reported),exhibiting a 4.5-fold increase in both H_(2)O_(2) production and FAL oxidation rates compared to the individual MOF components,achieving near-quantitative FAL conversion and exceptional selectivity.This work provides a potent design blueprint,emphasizing interfacial engineering and structural synergy for unprecedented efficiency and selectivity in sustainable chemical transformations.
基金supported by the National Natural Science Foundation of China(Nos.52302272 and 52377026)the Taishan Scholars Program(Nos.tsqn202211124 and tsqn202103057)+4 种基金the Natural Science Foundation of Shandong Province(Nos.ZR2022QB023 and ZR2024ME046)the Qingchuang Talents Induction Program of Shandong Higher Education Insti-tution(Research and Innovation Team of Marine Polysaccharides Fibers-based Energy Materials)the Key Innovative Research Team of New Energy Materials and Devices(No.BBXYKYTDxjZD01)the University Natural Science Research Project of Anhui Province(No.2022AH010101)the State Key Laboratory of Bio-Fibers and Eco-Textiles,Qingdao University(Nos.ZKT10 and GZRC202006).
文摘Anion exchange membrane electrolysis (AEMWE) is currently a promising technology to produce hydrogen from water. Developing the highly intrinsic activity of electrodes is extremely important. In this paper, nitrogen vacancies-rich cobalt nitride (Co_(4)N-VN) is used as the anode catalyst of the urea oxidation reaction (UOR) and its loading Pt (Pt@Co_(4)N-VN) acted as the cathode of hydrogen evolution reaction (HER). The introduction of N-vacancies gained the electron-deficient Co_(4)N more favorable for the UOR process. Meanwhile, the electron transfer between the Co_(4)N-VN carrier and Pt can enhance the intrinsic HER activity of loaded Pt. Specifically, in the 0.33 M urea and 1.0 M KOH electrolyte, the UOR potential of CO_(4)N-VN is only 1.58 V at the current density of 300.0 mA cm^(-2), which is much lower than that of Co_(4) N and Co_(3)O_(4). At the same time, the HER overpotential at 1.0 M KOH and 300.0 mA cm^(-2) is only 120.0 mV, lower than 20 wt% Pt/C. By measuring the bode phase diagram, the presence of N-vacancies can accelerate the electron transfer rate of catalysts to improve the UOR and HER electrocatalytic activity. The overall water-splitting device featuring Pt@Co_(4)N-VN||Co_(4)N-VN electrodes achieves a voltage of 2.99 V at a current density of 300.0 mA cm^(-2).
文摘There is a need for more focus in understanding the economic benefits of Climate-Smart Agriculture(CSA)interventions,particularly in sub-Saharan Africa,where extreme climate events are significantly affecting agriculture and rural livelihoods.This study used the Net Present Value(NPV),Internal Rate of Return(IRR),Benefit-Cost Ratio(BCR),and payback period to evaluate the economic viability of the adopted CSA interventions in the three villages(Doggoh,Jeffiri,and Wulling)of the dryland farming systems of northern Ghana,where CSA interventions were mostly practiced.Data were collected from 161 farm households by the questionnaire survey.The results showed that CSA interventions including livestock-crop integration,mixed cropping,crop rotation,nutrient integration,and tie ridging enhanced crop yield and the household income of smallholder farmers.The five CSA interventions selected by smallholders were in the following order of priority:livestock-crop integration(BCR=2.87),mixed cropping(BCR=2.54),crop rotation(BCR=2.24),nutrient integration(BCR=1.98),and tie ridging(BCR=1.42).Results further showed that livestock-crop integration was the most profitable CSA intervention even under a pessimistic assumption with a long payback period of 5.00 a.Moreover,this study indicated that the implementation of CSA interventions,on average,was relatively profitable and had a nominal financial risk for smallholder farmers.Understanding the economic viability of CSA interventions will help in decision-making process toward selecting the right CSA interventions for resilience development.
