The microstructure formation and grains refinement of two Mg-based alloys,i.e.AZ31 and AZ91D,were reported using an electromagnetic vibration(EMV) technique.These two alloys were solidified at various vibration freque...The microstructure formation and grains refinement of two Mg-based alloys,i.e.AZ31 and AZ91D,were reported using an electromagnetic vibration(EMV) technique.These two alloys were solidified at various vibration frequencies and the microstructures were observed.The average size of grains was quantitatively measured as a function of vibration frequencies. Moreover,the grain size distribution was outlined versus number fraction.A novel model was proposed to account for the microstructure formation and grain refinement when considering the significant difference of the electrical resistivity properties of the solid and the liquid during EMV processing in the semisolid state.The remarkable difference originates uncoupled movement between the mobile solid and the sluggish liquid,which can activate melt flow.The microstructure evolution can be well explained when the fluid flow intensity versus vibration frequency is taken into account.Moreover,the influence of the static magnetic field on texture formation is also considered,which plays an important role at higher vibration frequencies.展开更多
A rolling with cone-shaped roll, the diameter of which continuously varies along the axial direction, has been proposed as a new shear rolling for controlling the texture of an aluminum alloy sheet. In this study, var...A rolling with cone-shaped roll, the diameter of which continuously varies along the axial direction, has been proposed as a new shear rolling for controlling the texture of an aluminum alloy sheet. In this study, variations in the texture and Lankford value of a 1070 aluminum sheet rolled by the cone-shaped roll were investigated. Rolling with the cone-shaped roll was found to impose intense shear strain at the edges of the specimen, specifically near the surface. The shear directions in the left and right portions of the specimen were opposite to each other. The surface and middle layer of the specimen rolled by the cone-shaped roll and the reference specimen were characterized by a shear texture and typical recrystallization texture components, respectively. Notably, the specimen rolled by the cone-shaped roll exhibited smaller texture intensity than the reference specimen, especially at the surface, and the shear texture-components were observed at relatively deeper positions. As a result of Lankford value measurements, the specimen rolled with the cone-shape roll exhibited a smaller planar anisotropy than the reference specimen and an average Lankford value close to unity, which are likely due to the texture modifications introduced during rolling with the cone-shaped roll.展开更多
Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of t...Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research was to study two northern California wild-land fires: Butte Humboldt Complex and Butte Lightning Complex of 2008 and assessment of vegetation recovery after the fires via ground based measurements and utilization of Landsat 5 imagery and analysis software to assess landscape change. Multi-temporal and burn severity dynamics and assessment through satellite imagery were used to visually ascertain levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Normalized Burn Ratio (NBR) and delta NBR (DNBR) data allowed for quantitative analysis of burn severity levels. DNBR results indicate low severity and low re-growth for Butte Humboldt Complex “burned center” subplots. In contrast, DNBR values for Butte Lightning Complex “burned center” subplots indicated low-moderate burn severity levels.展开更多
Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we p...Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we propose a facile thermal-induced phase-segregation strategy to simultaneously master material operando strain and reconstruction effects for enhanced oxygen-evolving reaction(OER).Specifically,self-assembled and controllable layered LiCoO_(2)phase and Co_(3)O_(4)spinel can be generated from pristine Li2Co_(2)O_(4)spinel via Li and O volatilization under different temperatures,realizing controllable proportions of two phases by calcination temperature.Combined operando and ex-situ characterizations reveal that obvious tensile strain along(003)plane appears on layered LixCoO_(2)phase during OER,while low-valence Co_(3)O_(4)phase transforms into high-valence CoOOHx,realizing simultaneous operando strain and reconstruction effects.Further experimental and computational investigations demonstrate that both strained LixCoO_(2)phase and reconstructed CoOOHxcompound contribute to the beneficial adsorption of important OH-reactants,while respective roles in activity and stability are uncovered by exploring their latticeoxygen participation mechanism.This work not only reveals material operando strain effects during OER,but also inaugurates a new thermal-induced phase-segregation strategy to artificially master material operando strain and reconstruction effects,which will enlighten rational material design for many potential reactions and applications.展开更多
With a rising energy demand and anabatic environmental crisis arising from the fast growth in human population and society economics,numerous efforts have been devoted to explore and design plentiful multifunctional m...With a rising energy demand and anabatic environmental crisis arising from the fast growth in human population and society economics,numerous efforts have been devoted to explore and design plentiful multifunctional materials for meeting highefficiency energy transfer processes,which happen in various developed energy conversion and storage systems.As a special kind of multi-metal oxides,perovskite with attractive physical and chemical properties,is becoming a rapidly rising star on the horizon of high-performance catalytic materials with substantial research behaviors worldwide.The porous nanostructure in targeted catalysts is favorable to the catalytic activity and thus improves the overall efficiency of these energy-related installations.In this review paper,recent advances made in the porous perovskite nanostructures for catalyzing several anodic or cathodic reactions in fuel cells and metal-air batteries are comprehensively summarized.Plenty of general preparation methods employed to attain porous perovskite-type oxides are provided,followed by a further discussion about the influence of various strategies on structures and catalytic properties of the porous perovskites.Furthermore,deep insights gathered in the future development of porous perovskite-based materials for energy conversion and storage technologies are also provided.展开更多
Zinc-air batteries(ZABs)are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions(ORR/OER).Herein,the bifunctional catalyst consisting of MXene...Zinc-air batteries(ZABs)are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions(ORR/OER).Herein,the bifunctional catalyst consisting of MXene and metal compounds has been constructed via a controllable strategy.For demonstration,a 3D MXene framework with anchored heterostructure CoNi/CoNiP and nitrogen-doped carbon(NC)called H-CNP@M is constructed by metal-ion inducement and phosphorization.The bimetal-semiconductor heterostructure greatly enhances the catalytic performance.The H-CNP@M exhibits superior activities to-Ward ORR(E_(i/2)=0.833V)and OER(η_(10)=294 mV).Both aqueous and all-solid-state ZAB assembled with H-CNP@M demonstrate superior performance(peak power density of 166.5 mW/cm^(2)in aqueous case).This work provides a facile and general strategy to prepare MXene-supported bimetallic heterostructure for high-performance electrochemical energy devices.展开更多
Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7...Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.展开更多
Development of noble-metal-free materials with remarkable electrocatalytic water-splitting performance in acidic or neutral media has sparked considerable attention in recent years.Herein,we review the latest research...Development of noble-metal-free materials with remarkable electrocatalytic water-splitting performance in acidic or neutral media has sparked considerable attention in recent years.Herein,we review the latest research on design and fabrication of precious-metal-free catalytic materials for overall water electrolysis in non-alkaline environment,especially highlighting several optimizing approaches to enhance the catalytic behavior and to realize effective bifunctional electrocatalysts.All these involved noble-metal-free electrocatalysts are classified into transition-metal oxides(TMOs),transition-metal nitrides(TMNs),transition-metal carbides(TMCs),transition-metal phosphides(TMPs),transition-metal chalcogenides,metal complexes,and metal-free carbons,as shown in the main part.Besides,the paper also offers an introduction of the fundamental electrochemistry of water splitting before entering the subject,as well as a prospective discussion on mechanism understanding,novel catalysts fabrication,and standardized performance measurements/evaluation in the last section.展开更多
This paper explores approaches concerning complex forest planning challenges, such as restoration after large-scale disturbances and under climate change. It introduces a new framework that integrates qualitative scen...This paper explores approaches concerning complex forest planning challenges, such as restoration after large-scale disturbances and under climate change. It introduces a new framework that integrates qualitative scenario planning with quantitative multi-criteria decision analysis. This framework allows stakeholders without background in forestry to express their preferences as a set of scenarios that are further assessed for specific forest management goals and activities using multi-criteria models. The assessment of the modelled scenarios created a common understanding for the stakeholders and experts to compare trade-offs between several management options and needed policy choices. The framework was applied in the case study of forest restoration following insect disturbance in British Columbia, Canada. The framework enabled structured stakeholder groups’ interactions such as industry, business associations, local and regional governments, and non-governmental organizations to identify potential restoration options. Different community futures were envisioned by two scenarios: one resembling current conditions and standard practices, while another promoting diversification of the forestry sector. The results indicated that each of the scenarios leads to different consequences for the community measured by levels of economic benefits, total harvest volumes and harvest flows over time. The results also show that the developed framework linking scenarios and multi-criteria decision analyses proved crucial to broaden the discussion on relevant species mixes and management practices, and their implications for the community and policy development.展开更多
Objectives: More than a year after its introduction, COVID-19 vaccination coverage was low in the Togolese population and little data were available on its benefits for hospitalized patients. This study aimed to descr...Objectives: More than a year after its introduction, COVID-19 vaccination coverage was low in the Togolese population and little data were available on its benefits for hospitalized patients. This study aimed to describe the impact of COVID-19 vaccination on the prognosis of hospitalized patients. Methods: This was a retrospective cohort study of patients admitted to the Centre Hospitalier Régional Lomé Commune (Togo) between June 1, 2021 and May 31, 2022. Primary outcomes (admission to the intensive care unit and death) were presented with frequency and proportion. Mortality rates were presented by sociodemographic and clinical characteristics and compared by appropriate statistical tests. Factors associated with inpatient death were described by performing a Cox proportional hazard regression. Results: A total of 604 patients were hospitalized (50.0% women). The mean age was 54.03 ±17.1 years. Only 55 patients were fully vaccinated (9.1%). ICU admission was significantly more frequent in unvaccinated patients than in vaccinated ones (63.0% vs. 38.2%;p Conclusion: COVID-19 vaccination had a significant benefit for patients with COVID-19 infection in terms of reducing the risk of death. Based on real-world data from sub-Saharan Africa, this information can help optimize the benefit of COVID-19 vaccination by raising community awareness and increasing vaccine coverage while reducing hesitancy.展开更多
With the rapid development of aviation industry and its increasing impact on the global climate change,the contributions of carbon emissions frominternational flights are attracting more and more attention worldwide.T...With the rapid development of aviation industry and its increasing impact on the global climate change,the contributions of carbon emissions frominternational flights are attracting more and more attention worldwide.This study,taking Macao as the aviation hub,established the cross-border aviation carbon emission evaluation model to explore dynamic carbon emissions and net-zero path of international flights.The aviation hubmainly covers 58 routes and five types of civil aircraft from 12 countries or regions during 2000-2022.The results show that the aviation transportation in Macao emitted about 1.44 million tons CO_(2)eq in 2019,which is high 3.6 times that of 2000.The COVID-19 has led to a rapid decline in aviation carbon emissions in a short period of time,carbon emissions in 2020 decreased by 80%compared to 2019.In terms of cumulative carbon emissions from 2000 to 2019,the A321 and A320 Airbus contribute to 80%of carbon emissions.And the Chinese mainland(37%)and Taiwan(29%)are the main sources of emissions.In 2000-2019,the proportion of carbon emissions from China(including Taiwan and Hong Kong)decrease from 91%to 53%,while the contribution from Southeast Asia(from 5% to 26%),Japan and South Korea(from 2% to 19%)keep the growth trends.In the optimal scenario(B3C3),net zero emissions of cross-border aviation in Macao can be not achieved,and there is still only by removing 0.3 million tons CO_(2)eq.Emission reduction technology and new energy usage are priorities for the aviation emission reduction.展开更多
The intensification of climate change action has made air conditioners a key target for emission reductions.This study examines the factors influencing residents’willingness to buy(WTB)and willingness to pay(WTP)for ...The intensification of climate change action has made air conditioners a key target for emission reductions.This study examines the factors influencing residents’willingness to buy(WTB)and willingness to pay(WTP)for green air conditioners across six cities in the Pearl River Delta(PRD)region,aiming to understand consumer behavior and inform targeted market strategies.Using a novel Contingent Valuation Method(CVM),this study surveyed 1732 residents through online and face-to-face interviews.Binary logistic and ordered logistic regression analyses identified key factors affecting WTB and WTP,including gender,income,education,knowledge of green air conditioners,and confidence in their emission reduction potential.However,the study reveals significant regional disparities in WTP and payment amounts through the Kruskal-Wallis H and Mann-Whitney U tests.The results also highlight Shenzhen has significant difference and highest payment value than other cities.These findings provide valuable insights into regional disparities and common factors in green consumption,offering guidance for market strategies and policy development aimed at promoting green air conditioners.展开更多
Rainfall infiltration is one of the most important driving factors of geological hazards, ecological environment problems, and engineering accidents. Understanding the principle of soil wetting during rainfall infiltr...Rainfall infiltration is one of the most important driving factors of geological hazards, ecological environment problems, and engineering accidents. Understanding the principle of soil wetting during rainfall infiltration and its influence on soil mechanical properties is crucial for preventing geological hazards. In this study, micro-penetration tests coupled with moisture monitoring were performed to investigate the infiltration process during wetting through the measured change in mechanical characteristics. Results show that penetration resistance increases in the deep layer gradually. With increasing infiltration time,the wetting front keeps moving downward, and its range becomes wider. A slight increase of the penetration resistance in the shallow layer(d ≤ 17.5 mm) is observed. However, the penetration resistance in the middle layer(22.5 mm ≤ d ≤ 32.5 mm) decreases firstly before a slight increase. In the deep layer(d ≥ 37.5 mm), the penetration resistance decreases continuously during infiltration. Based on the measured water content profile during infiltration, it is found that the evolution of soil mechanical characteristics is fully responsible by the infiltration-induced re-distribution of water content along depth. Generally, the penetration resistance decreases exponentially with increasing water content in the soil. When the water content is low, wetting can weaken soil strength significantly, whereas this effect diminishes when the moisture surpasses a certain threshold. The results highlight that the penetration curves and water content profile show close inter-dependency and consistency, which verifies the feasibility of using micro-penetration to investigate rainfall infiltration and wetting process in surface soil layer or laboratory small-scale soil samples. This method enables fast, versatile and high-resolution measurements of infiltration process and moisture distribution in soil.展开更多
Lake area is an important indicator for climate change and its relationship with climatic factors is critical for understanding the mechanisms that control lake level changes. In this study, lake area changes and thei...Lake area is an important indicator for climate change and its relationship with climatic factors is critical for understanding the mechanisms that control lake level changes. In this study, lake area changes and their rela- tions to precipitation were investigated using multi-temporal Landsat Thermatic Mapper （TM） and Enhanced Thermatic Mapper plus （ETM＋） images collected from 10 different regions of Mongolia since the late 1980s. A lin- ear-regression analysis was applied to examine the relationship between precipitation and lake area change for each region and across different regions of Mongolia. The relationships were interpreted in terms of regional climate regime and hydromorphological characteristics. A total of 165 lakes with areas greater than 10 hm2 were identified from the Landsat images, which were aggregated for each region to estimate the regional lake area. Temporal lake area variability was larger in the Gobi regions, where small lakes are densely distributed. The regression analyses indicated that the regional patterns of precipitation-driven lake area changes varied considerably （R2=0.028-0.950）, depending on regional climate regime and hydromorphological characteristics. Generally, the lake area change in the hot-and-dry Gobi regions showed higher correlations with precipitation change. The precedent two-month pre- cipitation was the best determining factor of lake area change across Mongolia. Our results indicate the usefulness of regression analysis based on satellite-derived multi-temporal lake area data to identify regions where factors other than precipitation might play important roles in determining lake area change.展开更多
The effect of the cooling slope on the structure of Zr-based metallic glass matrix composites was investigated by changing the cooling slope.The synthesis of bulk metallic glass composites was made by a process combin...The effect of the cooling slope on the structure of Zr-based metallic glass matrix composites was investigated by changing the cooling slope.The synthesis of bulk metallic glass composites was made by a process combining cooling slope casting and Cu mold casting for Zr66.4Nb6.4Cu10.5Ni8.7Al8 alloys.The results show that the semisolid slurry which consists of the spheroidal or rosette-type BCC crystals and the liquid phase which forms metallic glass phase can be formed by the cooling slope process in this alloy system.However,the semisolid slurry cannot reach to the mold.It is considered that higher viscosity of the liquid phase which forms metallic glass phase causes this result.Thus,parameters of the cooling slope have to be examined further.展开更多
Thermal management in solid oxide fuel cells(SOFC)is a critical issue due to non-uniform electrochemical reactions and convective fl ows within the cells.Therefore,a 2D mathematical model is established herein to inve...Thermal management in solid oxide fuel cells(SOFC)is a critical issue due to non-uniform electrochemical reactions and convective fl ows within the cells.Therefore,a 2D mathematical model is established herein to investigate the thermal responses of a tubular methanol-fueled SOFC.Results show that unlike the low-temperature condition of 873 K,where the peak temperature gradient occurs at the cell center,it appears near the fuel inlet at 1073 K because of the rapid temperature rise induced by the elevated current density.Despite the large heat convection capacity,excessive air could not eff ectively eliminate the harmful temperature gradient caused by the large current density.Thus,optimal control of the current density by properly selecting the operating potential could generate a local thermal neutral state.Interestingly,the maximum axial temperature gradient could be reduced by about 18%at 973 K and 20%at 1073 K when the air with a 5 K higher temperature is supplied.Additionally,despite the higher electrochemical performance observed,the cell with a counter-fl ow arrange-ment featured by a larger hot area and higher maximum temperature gradients is not preferable for a ceramic SOFC system considering thermal durability.Overall,this study could provide insightful thermal information for the operating condition selection,structure design,and stability assessment of realistic SOFCs combined with their internal reforming process.展开更多
Urban sustainability assessment is an effective method for objectively presenting the current state of sustainable urban development and diagnosing sustainability-related issues.As the global community intensifies its...Urban sustainability assessment is an effective method for objectively presenting the current state of sustainable urban development and diagnosing sustainability-related issues.As the global community intensifies its efforts to implement the sustainable development goals(SDGs),the demand for assessing progress in urban sustainable development has increased.This has led to the emergence of numerous indicator systems with varying scales and themes published by different entities.Cities participating in these evaluations often encounter difficulties in matching indicators or the absence of certain indicators.In this context,urban decision makers and planners urgently need to identify substitute indicators that can express the semantic meaning of the original indicators and consider the availability of indicators for participating cities.Hence,this study explores the relationships of substitution between indicators and constructs a collection of substitute indicators to serve as a reference for sustainable urban development assessment.Specifically,building on a review of international and Chinese indicators related to urban sustainability assessment,this study employs natural semantic analysis methods based on the Word2Vec model and cosine similarity algorithm to calculate the similarity between indicators related to sustainable urban development.The results show that the Skip-gram algorithm with a word vector dimensionality of 600 has the best performance in terms of calculating the similarity between sustainable urban development assessment indicators.The findings provide valuable insights into selecting substitute indicators for future sustainable urban development assessment,particularly in China.展开更多
Droughts have serious and widespread impacts on crop production with substantial economic losses. The frequency and severity of drought events may increase in the future due to climate change. We have developed three ...Droughts have serious and widespread impacts on crop production with substantial economic losses. The frequency and severity of drought events may increase in the future due to climate change. We have developed three meteorological drought scenarios for Austria in the period 2008-2040. The scenarios are defined based on a dry day index which is combined with bootstrapping from an observed daily weather dataset of the period 1975-2007. The severity of long-term drought scenarios is characterized by lower annual and seasonal precipitation amounts as well as more significant temperature increases compared to the observations. The long-term impacts of the drought scenarios on Austrian crop production have been analyzed with the biophysical process model EPIC (Environmental Policy Integrated Climate). Our simulation outputs show that—for areas with historical mean annual precipitation sums below 850 mm— already slight increases in dryness result in significantly lower crop yields i.e. depending on the drought severity, between 0.6% and 0.9% decreases in mean annual dry matter crop yields per 1.0% decrease in mean annual precipitation sums. The EPIC results of more severe droughts show that spring and summer precipitation may become a limiting factor in crop production even in regions with historical abundant precipitation.展开更多
文摘The microstructure formation and grains refinement of two Mg-based alloys,i.e.AZ31 and AZ91D,were reported using an electromagnetic vibration(EMV) technique.These two alloys were solidified at various vibration frequencies and the microstructures were observed.The average size of grains was quantitatively measured as a function of vibration frequencies. Moreover,the grain size distribution was outlined versus number fraction.A novel model was proposed to account for the microstructure formation and grain refinement when considering the significant difference of the electrical resistivity properties of the solid and the liquid during EMV processing in the semisolid state.The remarkable difference originates uncoupled movement between the mobile solid and the sluggish liquid,which can activate melt flow.The microstructure evolution can be well explained when the fluid flow intensity versus vibration frequency is taken into account.Moreover,the influence of the static magnetic field on texture formation is also considered,which plays an important role at higher vibration frequencies.
基金Japan Aluminum Association for the financial aid extended to this study
文摘A rolling with cone-shaped roll, the diameter of which continuously varies along the axial direction, has been proposed as a new shear rolling for controlling the texture of an aluminum alloy sheet. In this study, variations in the texture and Lankford value of a 1070 aluminum sheet rolled by the cone-shaped roll were investigated. Rolling with the cone-shaped roll was found to impose intense shear strain at the edges of the specimen, specifically near the surface. The shear directions in the left and right portions of the specimen were opposite to each other. The surface and middle layer of the specimen rolled by the cone-shaped roll and the reference specimen were characterized by a shear texture and typical recrystallization texture components, respectively. Notably, the specimen rolled by the cone-shaped roll exhibited smaller texture intensity than the reference specimen, especially at the surface, and the shear texture-components were observed at relatively deeper positions. As a result of Lankford value measurements, the specimen rolled with the cone-shape roll exhibited a smaller planar anisotropy than the reference specimen and an average Lankford value close to unity, which are likely due to the texture modifications introduced during rolling with the cone-shaped roll.
文摘Wild-land fires are a dynamic and destructive force in natural ecosystems. In recent decades, fire disturbances have increased concerns and awareness over significant economic loss and landscape change. The focus of this research was to study two northern California wild-land fires: Butte Humboldt Complex and Butte Lightning Complex of 2008 and assessment of vegetation recovery after the fires via ground based measurements and utilization of Landsat 5 imagery and analysis software to assess landscape change. Multi-temporal and burn severity dynamics and assessment through satellite imagery were used to visually ascertain levels of landscape change, under two temporal scales. Visual interpretation indicated noticeable levels of landscape change and relevant insight into the magnitude and impact of both wild-land fires. Normalized Burn Ratio (NBR) and delta NBR (DNBR) data allowed for quantitative analysis of burn severity levels. DNBR results indicate low severity and low re-growth for Butte Humboldt Complex “burned center” subplots. In contrast, DNBR values for Butte Lightning Complex “burned center” subplots indicated low-moderate burn severity levels.
基金funded by the Australian Research Council Discovery Projects(DP160104835,Z.Shao)the Guangdong Basic and Applied Basic Research Foundation(2023A1515012878,D.Guan)+1 种基金the PolyU Distinguished Postdoctoral Fellowship Scheme(1-YWBU,D.Guan)the support from the Max Planck-POSTECH-Hsinchu Center for Complex Phase Materials。
文摘Material strain and reconstruction effects are critical for catalysis reactions,but current insights into operando strain effects during reaction and means to master catalyst reconstruction are still lacking.Here,we propose a facile thermal-induced phase-segregation strategy to simultaneously master material operando strain and reconstruction effects for enhanced oxygen-evolving reaction(OER).Specifically,self-assembled and controllable layered LiCoO_(2)phase and Co_(3)O_(4)spinel can be generated from pristine Li2Co_(2)O_(4)spinel via Li and O volatilization under different temperatures,realizing controllable proportions of two phases by calcination temperature.Combined operando and ex-situ characterizations reveal that obvious tensile strain along(003)plane appears on layered LixCoO_(2)phase during OER,while low-valence Co_(3)O_(4)phase transforms into high-valence CoOOHx,realizing simultaneous operando strain and reconstruction effects.Further experimental and computational investigations demonstrate that both strained LixCoO_(2)phase and reconstructed CoOOHxcompound contribute to the beneficial adsorption of important OH-reactants,while respective roles in activity and stability are uncovered by exploring their latticeoxygen participation mechanism.This work not only reveals material operando strain effects during OER,but also inaugurates a new thermal-induced phase-segregation strategy to artificially master material operando strain and reconstruction effects,which will enlighten rational material design for many potential reactions and applications.
基金the funding support(Project Number.PolyU 152214/17E)from Research Grant Council,University Grants Committee,Hong Kong SARthe financial support from National Nature Science Foundation of China under contract No.21878158the National Key Research and Development Program of China under contract No.2018YFB0905402
文摘With a rising energy demand and anabatic environmental crisis arising from the fast growth in human population and society economics,numerous efforts have been devoted to explore and design plentiful multifunctional materials for meeting highefficiency energy transfer processes,which happen in various developed energy conversion and storage systems.As a special kind of multi-metal oxides,perovskite with attractive physical and chemical properties,is becoming a rapidly rising star on the horizon of high-performance catalytic materials with substantial research behaviors worldwide.The porous nanostructure in targeted catalysts is favorable to the catalytic activity and thus improves the overall efficiency of these energy-related installations.In this review paper,recent advances made in the porous perovskite nanostructures for catalyzing several anodic or cathodic reactions in fuel cells and metal-air batteries are comprehensively summarized.Plenty of general preparation methods employed to attain porous perovskite-type oxides are provided,followed by a further discussion about the influence of various strategies on structures and catalytic properties of the porous perovskites.Furthermore,deep insights gathered in the future development of porous perovskite-based materials for energy conversion and storage technologies are also provided.
基金supported by Natural Science Foundation of Jiangsu Province(No.BK20200406)National Natural Science Foundation of China(Nos.51731004,22075263,52002366)+2 种基金National Key R&D Program of China(No.2021YFA1501502)the Fundamental Research Funds for the Central Universities(No.WK2060000039)the Collaborative Research Fund(No.C5031-20G)from Research Grant Council,University Grants Committee,Hong Kong SAR,and Project of Strategic Importance Program of The Hong Kong Polytechnic University(No.P0035168).
文摘Zinc-air batteries(ZABs)are regarded as promising next-generation energy storage devices but limited by their sluggish oxygen reduction/evolution reactions(ORR/OER).Herein,the bifunctional catalyst consisting of MXene and metal compounds has been constructed via a controllable strategy.For demonstration,a 3D MXene framework with anchored heterostructure CoNi/CoNiP and nitrogen-doped carbon(NC)called H-CNP@M is constructed by metal-ion inducement and phosphorization.The bimetal-semiconductor heterostructure greatly enhances the catalytic performance.The H-CNP@M exhibits superior activities to-Ward ORR(E_(i/2)=0.833V)and OER(η_(10)=294 mV).Both aqueous and all-solid-state ZAB assembled with H-CNP@M demonstrate superior performance(peak power density of 166.5 mW/cm^(2)in aqueous case).This work provides a facile and general strategy to prepare MXene-supported bimetallic heterostructure for high-performance electrochemical energy devices.
基金supported by the Research Grants Council,University Grants Committee,Hong Kong SAR(Project Number:N_PolyU552/20)supported by the National Nature Science Foundation of China(22209138)Guangdong Basic and Applied Basic Research Foundation(2021A1515110464).
文摘Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.
基金M.Ni thanks the funding support(Project Number:PolyU 152214/17E and PolyU 152064/18E)from Research Grant Council,University Grants Committee,Hong Kong SAR。
文摘Development of noble-metal-free materials with remarkable electrocatalytic water-splitting performance in acidic or neutral media has sparked considerable attention in recent years.Herein,we review the latest research on design and fabrication of precious-metal-free catalytic materials for overall water electrolysis in non-alkaline environment,especially highlighting several optimizing approaches to enhance the catalytic behavior and to realize effective bifunctional electrocatalysts.All these involved noble-metal-free electrocatalysts are classified into transition-metal oxides(TMOs),transition-metal nitrides(TMNs),transition-metal carbides(TMCs),transition-metal phosphides(TMPs),transition-metal chalcogenides,metal complexes,and metal-free carbons,as shown in the main part.Besides,the paper also offers an introduction of the fundamental electrochemistry of water splitting before entering the subject,as well as a prospective discussion on mechanism understanding,novel catalysts fabrication,and standardized performance measurements/evaluation in the last section.
文摘This paper explores approaches concerning complex forest planning challenges, such as restoration after large-scale disturbances and under climate change. It introduces a new framework that integrates qualitative scenario planning with quantitative multi-criteria decision analysis. This framework allows stakeholders without background in forestry to express their preferences as a set of scenarios that are further assessed for specific forest management goals and activities using multi-criteria models. The assessment of the modelled scenarios created a common understanding for the stakeholders and experts to compare trade-offs between several management options and needed policy choices. The framework was applied in the case study of forest restoration following insect disturbance in British Columbia, Canada. The framework enabled structured stakeholder groups’ interactions such as industry, business associations, local and regional governments, and non-governmental organizations to identify potential restoration options. Different community futures were envisioned by two scenarios: one resembling current conditions and standard practices, while another promoting diversification of the forestry sector. The results indicated that each of the scenarios leads to different consequences for the community measured by levels of economic benefits, total harvest volumes and harvest flows over time. The results also show that the developed framework linking scenarios and multi-criteria decision analyses proved crucial to broaden the discussion on relevant species mixes and management practices, and their implications for the community and policy development.
文摘Objectives: More than a year after its introduction, COVID-19 vaccination coverage was low in the Togolese population and little data were available on its benefits for hospitalized patients. This study aimed to describe the impact of COVID-19 vaccination on the prognosis of hospitalized patients. Methods: This was a retrospective cohort study of patients admitted to the Centre Hospitalier Régional Lomé Commune (Togo) between June 1, 2021 and May 31, 2022. Primary outcomes (admission to the intensive care unit and death) were presented with frequency and proportion. Mortality rates were presented by sociodemographic and clinical characteristics and compared by appropriate statistical tests. Factors associated with inpatient death were described by performing a Cox proportional hazard regression. Results: A total of 604 patients were hospitalized (50.0% women). The mean age was 54.03 ±17.1 years. Only 55 patients were fully vaccinated (9.1%). ICU admission was significantly more frequent in unvaccinated patients than in vaccinated ones (63.0% vs. 38.2%;p Conclusion: COVID-19 vaccination had a significant benefit for patients with COVID-19 infection in terms of reducing the risk of death. Based on real-world data from sub-Saharan Africa, this information can help optimize the benefit of COVID-19 vaccination by raising community awareness and increasing vaccine coverage while reducing hesitancy.
基金supported by the Science and Technology Development Fund,Macao SAR,China(Nos.0033/2022/AFJ and 0011/2023/AMJ)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515012017).
文摘With the rapid development of aviation industry and its increasing impact on the global climate change,the contributions of carbon emissions frominternational flights are attracting more and more attention worldwide.This study,taking Macao as the aviation hub,established the cross-border aviation carbon emission evaluation model to explore dynamic carbon emissions and net-zero path of international flights.The aviation hubmainly covers 58 routes and five types of civil aircraft from 12 countries or regions during 2000-2022.The results show that the aviation transportation in Macao emitted about 1.44 million tons CO_(2)eq in 2019,which is high 3.6 times that of 2000.The COVID-19 has led to a rapid decline in aviation carbon emissions in a short period of time,carbon emissions in 2020 decreased by 80%compared to 2019.In terms of cumulative carbon emissions from 2000 to 2019,the A321 and A320 Airbus contribute to 80%of carbon emissions.And the Chinese mainland(37%)and Taiwan(29%)are the main sources of emissions.In 2000-2019,the proportion of carbon emissions from China(including Taiwan and Hong Kong)decrease from 91%to 53%,while the contribution from Southeast Asia(from 5% to 26%),Japan and South Korea(from 2% to 19%)keep the growth trends.In the optimal scenario(B3C3),net zero emissions of cross-border aviation in Macao can be not achieved,and there is still only by removing 0.3 million tons CO_(2)eq.Emission reduction technology and new energy usage are priorities for the aviation emission reduction.
基金funded by the Science and Technology Development Fund,Macao SAR,China(Nos.0033/2022/AFJ,0011/2023/AMJ,and 001/2022/NIF)the Guangdong Basic and Applied Basic Research Foundation,China(Nos.2023A1515012017).
文摘The intensification of climate change action has made air conditioners a key target for emission reductions.This study examines the factors influencing residents’willingness to buy(WTB)and willingness to pay(WTP)for green air conditioners across six cities in the Pearl River Delta(PRD)region,aiming to understand consumer behavior and inform targeted market strategies.Using a novel Contingent Valuation Method(CVM),this study surveyed 1732 residents through online and face-to-face interviews.Binary logistic and ordered logistic regression analyses identified key factors affecting WTB and WTP,including gender,income,education,knowledge of green air conditioners,and confidence in their emission reduction potential.However,the study reveals significant regional disparities in WTP and payment amounts through the Kruskal-Wallis H and Mann-Whitney U tests.The results also highlight Shenzhen has significant difference and highest payment value than other cities.These findings provide valuable insights into regional disparities and common factors in green consumption,offering guidance for market strategies and policy development aimed at promoting green air conditioners.
基金supported by the National Key Research and Development Program of China (Grant No. 2020YFC1808101)National Natural Science Foundation of China (Grant No. 41925012)+1 种基金Natural Science Foundation of Jiangsu Province (Grant No.BK20211087)the Fundamental Research Funds for the Central Universities。
文摘Rainfall infiltration is one of the most important driving factors of geological hazards, ecological environment problems, and engineering accidents. Understanding the principle of soil wetting during rainfall infiltration and its influence on soil mechanical properties is crucial for preventing geological hazards. In this study, micro-penetration tests coupled with moisture monitoring were performed to investigate the infiltration process during wetting through the measured change in mechanical characteristics. Results show that penetration resistance increases in the deep layer gradually. With increasing infiltration time,the wetting front keeps moving downward, and its range becomes wider. A slight increase of the penetration resistance in the shallow layer(d ≤ 17.5 mm) is observed. However, the penetration resistance in the middle layer(22.5 mm ≤ d ≤ 32.5 mm) decreases firstly before a slight increase. In the deep layer(d ≥ 37.5 mm), the penetration resistance decreases continuously during infiltration. Based on the measured water content profile during infiltration, it is found that the evolution of soil mechanical characteristics is fully responsible by the infiltration-induced re-distribution of water content along depth. Generally, the penetration resistance decreases exponentially with increasing water content in the soil. When the water content is low, wetting can weaken soil strength significantly, whereas this effect diminishes when the moisture surpasses a certain threshold. The results highlight that the penetration curves and water content profile show close inter-dependency and consistency, which verifies the feasibility of using micro-penetration to investigate rainfall infiltration and wetting process in surface soil layer or laboratory small-scale soil samples. This method enables fast, versatile and high-resolution measurements of infiltration process and moisture distribution in soil.
基金supported by research grants from Korea Forest Service (S211212L06301)from National Research Foundation of Korea (NRF-2013R1A1A4A01008632)supported by Kangwon National University (C1009843-01-01)
文摘Lake area is an important indicator for climate change and its relationship with climatic factors is critical for understanding the mechanisms that control lake level changes. In this study, lake area changes and their rela- tions to precipitation were investigated using multi-temporal Landsat Thermatic Mapper （TM） and Enhanced Thermatic Mapper plus （ETM＋） images collected from 10 different regions of Mongolia since the late 1980s. A lin- ear-regression analysis was applied to examine the relationship between precipitation and lake area change for each region and across different regions of Mongolia. The relationships were interpreted in terms of regional climate regime and hydromorphological characteristics. A total of 165 lakes with areas greater than 10 hm2 were identified from the Landsat images, which were aggregated for each region to estimate the regional lake area. Temporal lake area variability was larger in the Gobi regions, where small lakes are densely distributed. The regression analyses indicated that the regional patterns of precipitation-driven lake area changes varied considerably （R2=0.028-0.950）, depending on regional climate regime and hydromorphological characteristics. Generally, the lake area change in the hot-and-dry Gobi regions showed higher correlations with precipitation change. The precedent two-month pre- cipitation was the best determining factor of lake area change across Mongolia. Our results indicate the usefulness of regression analysis based on satellite-derived multi-temporal lake area data to identify regions where factors other than precipitation might play important roles in determining lake area change.
文摘The effect of the cooling slope on the structure of Zr-based metallic glass matrix composites was investigated by changing the cooling slope.The synthesis of bulk metallic glass composites was made by a process combining cooling slope casting and Cu mold casting for Zr66.4Nb6.4Cu10.5Ni8.7Al8 alloys.The results show that the semisolid slurry which consists of the spheroidal or rosette-type BCC crystals and the liquid phase which forms metallic glass phase can be formed by the cooling slope process in this alloy system.However,the semisolid slurry cannot reach to the mold.It is considered that higher viscosity of the liquid phase which forms metallic glass phase causes this result.Thus,parameters of the cooling slope have to be examined further.
基金by the Project of Strategic Importance Funding Scheme from The Hong Kong China Polytechnic University(No.P0035168)the National Natural Science Foundation of China(No.51806241).
文摘Thermal management in solid oxide fuel cells(SOFC)is a critical issue due to non-uniform electrochemical reactions and convective fl ows within the cells.Therefore,a 2D mathematical model is established herein to investigate the thermal responses of a tubular methanol-fueled SOFC.Results show that unlike the low-temperature condition of 873 K,where the peak temperature gradient occurs at the cell center,it appears near the fuel inlet at 1073 K because of the rapid temperature rise induced by the elevated current density.Despite the large heat convection capacity,excessive air could not eff ectively eliminate the harmful temperature gradient caused by the large current density.Thus,optimal control of the current density by properly selecting the operating potential could generate a local thermal neutral state.Interestingly,the maximum axial temperature gradient could be reduced by about 18%at 973 K and 20%at 1073 K when the air with a 5 K higher temperature is supplied.Additionally,despite the higher electrochemical performance observed,the cell with a counter-fl ow arrange-ment featured by a larger hot area and higher maximum temperature gradients is not preferable for a ceramic SOFC system considering thermal durability.Overall,this study could provide insightful thermal information for the operating condition selection,structure design,and stability assessment of realistic SOFCs combined with their internal reforming process.
基金supported by the National Key Research and Development Program of China under the theme“Key technologies for urban sustainable development evaluation and decision-making support” [Grant No.2022YFC3802900]the Guangxi Key Research and Development Program [Grant No.Guike AB21220057].
文摘Urban sustainability assessment is an effective method for objectively presenting the current state of sustainable urban development and diagnosing sustainability-related issues.As the global community intensifies its efforts to implement the sustainable development goals(SDGs),the demand for assessing progress in urban sustainable development has increased.This has led to the emergence of numerous indicator systems with varying scales and themes published by different entities.Cities participating in these evaluations often encounter difficulties in matching indicators or the absence of certain indicators.In this context,urban decision makers and planners urgently need to identify substitute indicators that can express the semantic meaning of the original indicators and consider the availability of indicators for participating cities.Hence,this study explores the relationships of substitution between indicators and constructs a collection of substitute indicators to serve as a reference for sustainable urban development assessment.Specifically,building on a review of international and Chinese indicators related to urban sustainability assessment,this study employs natural semantic analysis methods based on the Word2Vec model and cosine similarity algorithm to calculate the similarity between indicators related to sustainable urban development.The results show that the Skip-gram algorithm with a word vector dimensionality of 600 has the best performance in terms of calculating the similarity between sustainable urban development assessment indicators.The findings provide valuable insights into selecting substitute indicators for future sustainable urban development assessment,particularly in China.
文摘Droughts have serious and widespread impacts on crop production with substantial economic losses. The frequency and severity of drought events may increase in the future due to climate change. We have developed three meteorological drought scenarios for Austria in the period 2008-2040. The scenarios are defined based on a dry day index which is combined with bootstrapping from an observed daily weather dataset of the period 1975-2007. The severity of long-term drought scenarios is characterized by lower annual and seasonal precipitation amounts as well as more significant temperature increases compared to the observations. The long-term impacts of the drought scenarios on Austrian crop production have been analyzed with the biophysical process model EPIC (Environmental Policy Integrated Climate). Our simulation outputs show that—for areas with historical mean annual precipitation sums below 850 mm— already slight increases in dryness result in significantly lower crop yields i.e. depending on the drought severity, between 0.6% and 0.9% decreases in mean annual dry matter crop yields per 1.0% decrease in mean annual precipitation sums. The EPIC results of more severe droughts show that spring and summer precipitation may become a limiting factor in crop production even in regions with historical abundant precipitation.
