The low intrinsic activity of Fenton catalytic site and high demand for light-energy input inhibit the organic-pollution control efficiency of photo-Fenton process.Here,through structural design with density functiona...The low intrinsic activity of Fenton catalytic site and high demand for light-energy input inhibit the organic-pollution control efficiency of photo-Fenton process.Here,through structural design with density functional theory(DFT)calculations,Ce is predicted to enable the construction of coordinatively unsaturated metal centers(CUCs)in Prussian blue analogue(PBA),which can strongly adsorb H_(2)O_(2)and donate sufficient electrons for directly splitting the O-O bond to produceOH.Using a substitution-co-assembly strategy,binary Ce-Fe PBA is then prepared,which rapidly degrades sulfamethoxazole with the pseudo-first-order kinetic rate constant exceeding reported values by 1-2 orders of magnitude.Meanwhile,the photogenerated electrons reduce Fe(Ⅲ)and Ce(Ⅳ)to promote the metal valence cycle in CUCs and make sulfamethoxazole degradation efficiency only lose 6.04%in 5 runs.Overall,by introducing rare earth metals into transition metal-organic frameworks,this work guides the whole process for highly active CUCs from design and construction to mechanism exploration with DFT calculations,enabling ultrafast and stable photo-Fenton catalysis.展开更多
In highly dynamic and heterogeneous vehicular communication networks,it is challenging to efficiently utilize network resources and ensure demanding performance requirements of safetyrelated applications.This paper in...In highly dynamic and heterogeneous vehicular communication networks,it is challenging to efficiently utilize network resources and ensure demanding performance requirements of safetyrelated applications.This paper investigates machinelearning-assisted transmission design in a typical multi-user vehicle-to-vehicle(V2V)communication scenario.The transmission process proceeds sequentially along the discrete time steps,where several source nodes intend to deliver multiple different types of messages to their respective destinations within the same spectrum.Due to rapid movement of vehicles,real-time acquirement of channel knowledge and central coordination of all transmission actions are in general hard to realize.We consider applying multi-agent deep reinforcement learning(MADRL)to handle this issue.By transforming the transmission design problem into a stochastic game,a multi-agent proximal policy optimization(MAPPO)algorithm under a centralized training and decentralized execution framework is proposed such that each source decides its own transmission message type,power level,and data rate,based on local observations of the environment and feedback,to maximize its energy efficiency.Via simulations we show that our method achieves better performance over conventional methods.展开更多
To effectively improve the poor engineering properties of loess and enhance its seismic performance,the industrial by-product lignin is used as a modified material.Based on lots of dynamic triaxial tests,the dynamic e...To effectively improve the poor engineering properties of loess and enhance its seismic performance,the industrial by-product lignin is used as a modified material.Based on lots of dynamic triaxial tests,the dynamic elastic modulus and damping ratio of lignin-modified loess were tested.The effects of lignin content on the dynamic elastic modulus and damping ratio of lignin-modified loess were analyzed.Combined with scanning electron microscopy(SEM)and X-ray diffraction(XRD),the microscopic mechanism of lignin to improve the dynamic properties of loess was studied.The results show that lignin can effectively modify the dynamic deformation of loess under dynamic load.Under the same dynamic stress condition,the dynamic strain of lignin-modified loess is smaller than compacted loess.The dynamic elastic modulus of modified loess with different lignin content are quite different,but both decrease with the increase of dynamic strain.And the dynamic elastic modulus of modified loess is greater than compacted loess.The maximum dynamic elastic modulus of modified loess with a lignin content of 1%are significantly greater than others.Under the same dynamic strain condition,the damping ratio of lignin-modified loess is smaller than compacted loess.Lignin can effectively fill loess pores and cement loess particles.Compared with compacted loess,no new mineral components are generated in the lignin-modified loess.The optimum lignin content of dynamics characteristic of modified loess is present,and the optimum lignin content is 1%.展开更多
Heavy metals usually exist stably as the species of organic complexes in high-salinity wastewater.Therefore,their effective removal is challenging,especially when the initial p H is neutral.Herein,a novel nitrogen dop...Heavy metals usually exist stably as the species of organic complexes in high-salinity wastewater.Therefore,their effective removal is challenging,especially when the initial p H is neutral.Herein,a novel nitrogen doped biomass-based composite(N-CMCS)was synthesized to remove the complexed heavy metal of Cr(Ⅲ)-carboxyl.The maximum adsorption capacity of Cr(Ⅲ)-Citrate(Cr-Cit)by N-CMCS under neutral p H(7.0)and high-salinity(200 mmol/L NaCl)condition was up to 2.50 mmol/g.And the removal performance remained stable after 6 times of regeneration.Combined with species and characterizations analysis,electrostatic attraction and hydrogen bonding were the main mechanisms for N-CMCS to remove Cr(Ⅲ)-carboxyl complexes.Dynamic adsorption indicated N-CMCS column could treat about 1300BV simulated wastewater and 350 BV actual wastewater with the concentration of effluent lower than1.0 mg/L.Furthermore,N-CMCS could remove a variety of complexed heavy metal ions under neutral p H,indicating the great potential in practical application.展开更多
Non-precious metal single-atom catalysts(NPM-SACs)with unique electronic structures and coordination environments have gained much attention in electrocatalysis owing to their low cost,high atomic utilization,and high...Non-precious metal single-atom catalysts(NPM-SACs)with unique electronic structures and coordination environments have gained much attention in electrocatalysis owing to their low cost,high atomic utilization,and high performance.NPM-SACs on carbon support(NPM-SACs/CS)are promising because of the carbon substrate with a large surface area,excellent electrical conductivity,and high chemical stability.This review provides an overview of recent developments in NPM-SACs/CS for the electrocatalytic field.First,the state-of-the-art synthesis methods and advanced characterization techniques of NPM-SACs/CS are discussed in detail.Then,the structural adjustment strategy of NPM-SACs/CS for optimizing electrocatalytic performance is introduced concisely.Furthermore,we provide a comprehensive summary of recent advances in developing NPM-SACs/CS for important electrochemical reactions,including carbon dioxide reduction reaction,hydrogen evolution reaction,oxygen evolution reaction,oxygen reduction reaction,and nitrogen reduction reaction.In the end,the existing challenges and future opportunities of NPM-SACs/CS in the electrocatalytic field are highlighted.展开更多
Per- and polyfluoroalkyl substances (PFAS) pose serious human health and environmental risks due to their persistence and toxicity. Among the available PFAS remediation options, the electrochemical approach is promisi...Per- and polyfluoroalkyl substances (PFAS) pose serious human health and environmental risks due to their persistence and toxicity. Among the available PFAS remediation options, the electrochemical approach is promising with better control. In this review, recent advances in the decontamination of PFAS from water using several state-of-the-art electrochemical strategies, including electro-oxidation, electro-adsorption, and electro-coagulation, were systematically reviewed. We aimed to elucidate their design principles, underlying working mechanisms, and the effects of operation factors (e.g., solution pH, applied voltage, and reactor configuration). The recent developments of innovative electrochemical systems and novel electrode materials were highlighted. In addition, the development of coupled processes that could overcome the shortcomings of low efficiency and high energy consumption of conventional electrochemical systems was also emphasized. This review identified several major knowledge gaps and challenges in the scalability and adaptability of efficient electrochemical systems for PFAS remediation. Materials science and system design developments are forging a path toward sustainable treatment of PFAS-contaminated water through electrochemical technologies.展开更多
The influences of dewatered sludge blending ratio in coal on flammability index (C) and combustion characteristic index (S) and release of sulfur dioxide (SO2), nitrogen oxide (NOx), carbon monoxide (CO) and...The influences of dewatered sludge blending ratio in coal on flammability index (C) and combustion characteristic index (S) and release of sulfur dioxide (SO2), nitrogen oxide (NOx), carbon monoxide (CO) and heavy metals (Hg, As, Cd, Pb and Cr) were studied. The impact on combustion characteristics could be ignored if less than 20% of dewatered sludge was added in coal. Besides, emission pattern experiments of NOx, SO2, CO and heavy metals were carried out in a high-temperature tubular furnace. Results showed that the conversion rate of NOx and total emission of SO2 reduced with the increase of sludge adding ratio, and a better effect of fixing sulfur could be obtained when the blending ratio reached 30%. Concentrations and distributions of five types of heavy metals in different residues (bottom ash and fly ash) as well as in flue gas were analyzed. It was shown that the characteristics of coal and sludge, as well as the volatilization of heavy metals had a great influence on the distribution of heavy metals.展开更多
Global climate change,growing population,and environmental pollution underscore the need for a greater focus on providing advanced water treatment technologies.Although electrochemical basedprocesses are becoming prom...Global climate change,growing population,and environmental pollution underscore the need for a greater focus on providing advanced water treatment technologies.Although electrochemical basedprocesses are becoming promising solutions,they still face challenges owing to mass transport and upscaling which hinder the exploitation of this technology.Electrode design and reactor configuration are key factors for achieving operational improvements.The electroactive membrane has proven to be a breakthrough technology integrating electrochemistry and membrane separation with an enhanced mass transport by convection.In this review article,we discuss recent progress in environmental applications of electroactive membranes with particular focus on those composed of carbon nanotubes(CNT)due to their intriguing physicochemical prope rties.Their applications in degradation of refractory contaminants,detoxification and sequestration of toxic heavy metal ions,and membrane fouling alleviations are systematically reviewed.We then discuss the existing limitations and opportunities for future research.The development of advanced electroactive systems depends on interdisciplinary collaborations in the areas of materials,electrochemistry,membrane development,and environmental sciences.展开更多
A large proportion of Internet of Things (loT) applications are internally publish/subscribe in nature, and traditional architecture cannot support them efficiently and flexibly. In essence, supporting efficient pub...A large proportion of Internet of Things (loT) applications are internally publish/subscribe in nature, and traditional architecture cannot support them efficiently and flexibly. In essence, supporting efficient publish/subscribe systems requires data-oriented naming and efficient multicast. Since deployment of native IP-based multicast has failed, overlay-based multicast has become the practical choice. Since load balancing between heterogeneous nodes is an important issue, designing an optimal load balancing overlay net- work for publish/subscribe systems is a necessary endeavor. This study focuses on the optimal load balancing overlay design problem for topic-based publish/subscribe systems in a heterogeneous environment (in terms of node processing power, bandwidth, and reachability). The Minimum Idle Degree (MID) model is introduced to capture the heterogeneity of overlay nodes. Based on the MID model, new node load measures are defined that can accommodate heterogeneous server capacities and capture the node load in publish/subscribe systems more accurately than traditional measures. A new optimization problem, Maximum Minimum Idle Degree Topic-Connected Overlay (MMID-TCO), is established. This problem is NP-complete and a constant approximation algorithm does not exist for this problem (unless P=NP). Based on MID metrics, the Maximum Minimum Idle Degree Overlay Design Algorithm (MMID-ODA), which has polynomial time is introduced. To improve performance, an approach that breaks down the problem into several small-scale problems by exploiting the potential inherent disjoint characteristic in the subscription table is presented. Simulation results show that the proposed algorithm is able to achieve better load balance than MinMax-ODA in a heterogeneous environment.展开更多
As the essential technology of human-robotics interactive wearable devices,the robotic knee prosthesis can provide above-knee amputations with functional knee compensations to realize their physical and psychological ...As the essential technology of human-robotics interactive wearable devices,the robotic knee prosthesis can provide above-knee amputations with functional knee compensations to realize their physical and psychological social regression.With the development of mechanical and mechatronic science and technology,the fully active knee prosthesis that can provide subjects with actuating torques has demonstrated a better wearing performance in slope walking and stair ascent when compared with the passive and the semi-active ones.Additionally,with intelligent human-robotics control strategies and algorithms,the wearing effect of the knee prosthesis has been greatly enhanced in terms of stance stability and swing mobility.Therefore,to help readers to obtain an overview of recent progress in robotic knee prosthesis,this paper systematically categorized knee prostheses according to their integrated functions and introduced related research in the past ten years(2010−2020)regarding(1)mechanical design,including uniaxial,four-bar,and multi-bar knee structures,(2)actuating technology,including rigid and elastic actuation,and(3)control method,including mode identification,motion prediction,and automatic control.Quantitative and qualitative analysis and comparison of robotic knee prosthesis-related techniques are conducted.The development trends are concluded as follows:(1)bionic and lightweight structures with better mechanical performance,(2)bionic elastic actuation with energy-saving effect,(3)artificial intelligence-based bionic prosthetic control.Besides,challenges and innovative insights of customized lightweight bionic knee joint structure,highly efficient compact bionic actuation,and personalized daily multi-mode gait adaptation are also discussed in-depth to facilitate the future development of the robotic knee prosthesis.展开更多
A self-synthesized bi-pyridine chelating resin(PAPY)could separate Cu(Ⅱ)/Ni(Ⅱ)/Fe(Ⅱ)sequentially from strong-acidic pickling wastewater by a two-stage p H-adjusted process,in which Cu(Ⅱ),Ni(Ⅱ),and Fe(Ⅱ)were succ...A self-synthesized bi-pyridine chelating resin(PAPY)could separate Cu(Ⅱ)/Ni(Ⅱ)/Fe(Ⅱ)sequentially from strong-acidic pickling wastewater by a two-stage p H-adjusted process,in which Cu(Ⅱ),Ni(Ⅱ),and Fe(Ⅱ)were successively preferred by PAPY.In the first stage(p H 1.0),the separation factor of Cu(Ⅱ)over Ni(Ⅱ)reached 61.43 in Cu(Ⅱ)-Ni(Ⅱ)-Fe(Ⅱ)systems.In the second stage(p H 2.0),the separation factor of Ni(Ⅱ)over Fe(Ⅱ)reached 92.82 in Ni(Ⅱ)-Fe(Ⅱ)systems.Emphasis was placed on the selective separation of Cu(Ⅱ)and Ni(Ⅱ)in the first-stage.The adsorption amounts of Cu(Ⅱ)onto PAPY were 1.2 mmol/g in the first stage,while those of Ni(Ⅱ)and Fe(Ⅱ)were lower than 0.3 mmol/g.Cu(Ⅱ)adsorption was hardly affected by Ni(Ⅱ)with the presence of dense Fe(Ⅱ),but Cu(Ⅱ)inhibited Ni(Ⅱ)adsorption strongly.Part of preloaded Ni(Ⅱ)could be replaced by Cu(Ⅱ)based on the replacement effect.Compared with the absence of Fe(Ⅱ),dense Fe(Ⅱ)could obviously enhance the separation of Cu(Ⅱ)-Ni(Ⅱ).More than 95.0%of Cu(Ⅱ)could be removed in the former 240 BV(BV for bed volume of the adsorbent)in the fixed-bed adsorption column process with the flow rate of 2.5 BV/h.As proved by X-ray photoelectron spectrometry(XPS)and density functional theory(DFT)analyses,Cu(Ⅱ)exerted a much stronger deprotonation and chelation ability toward PAPY than Ni(Ⅱ)and Fe(Ⅱ).Thus,the work shows a great potential in the separation and purification of heavy metal resources from strong-acidic pickling wastewaters.展开更多
An efficient and profitable separation process was proposed to prepare 5N (the purity of the metal solution reaches 99.999%) high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performanc...An efficient and profitable separation process was proposed to prepare 5N (the purity of the metal solution reaches 99.999%) high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions, was explored quantitatively. The maximum adsorption capacity for copper was 2.286 mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing 5N-level high-purity nickel solutions, which was further verified using the 800 BV (bed volume) effluent in the column dynamic process. According to the cost-benefit analysis, purification contributed to a profit of approximately 60,000 USD per cycle, and the investment return period was less than 1/3 years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms, implying a coordination ratio of approximately 1:1.展开更多
Jishou Municipal Center for Disease Control and Prevention(Jishou CDC)received a phone call at 7:30 a.m.on April 24,2020 from Xiangxi Tujia and Miao Autonomous Prefectural CDC(Xiangxi CDC)that avian influenza A/H9N2 v...Jishou Municipal Center for Disease Control and Prevention(Jishou CDC)received a phone call at 7:30 a.m.on April 24,2020 from Xiangxi Tujia and Miao Autonomous Prefectural CDC(Xiangxi CDC)that avian influenza A/H9N2 virus was detected by quantitative reverse transcription-polymerase chain reaction(RT-PCR)from the throat swab sample of an influenza-like illness in an outpatient in the Xiangxi Traditional Chinese Medicine Hospital.展开更多
Lean Blow Out(LBO)poses a significant safety hazard when occurring in aero-engines.Understanding the lower stability limits of gas turbine combustors and the characteristics of spray flame close to LBO are imperative ...Lean Blow Out(LBO)poses a significant safety hazard when occurring in aero-engines.Understanding the lower stability limits of gas turbine combustors and the characteristics of spray flame close to LBO are imperative for safe operation.The objective of this work is to evaluate the effects of fuel decreasing rates and pressure drops of the injector on LBO performances in a multiswirl staged combustor equipped with an airblast injector.A set of hardware and control system was developed to realize a user-defined fuel supply law.High-speed imaging was applied to record complete LBO processes under the conditions of linear fuel reduction and stable airflow.Partical Image Velocimetry(PIV)and Planar Mie(PMie)scattering were used to acquire the flow fields and spray fields under non-reacting conditions.Experimental results have shown that LBO limits extend to leaner conditions as the pressure drop of the injector increases.With an increase of the fuel decreasing rate,the exhaust temperature before flame extinction increases,and the LBO Fuel-to-Air-Ratio(FAR)decreases.The time evolution of the integral CH*intensity conforms to a linear function during the LBO process.Proper Orthogonal Decomposition(POD)was used to analyze the dynamic characteristics of lean-burn flames.Under different fuel decreasing rates and pressure drops of the injector,flames close to LBO present similar modal spatial distributions,alternately appearing axial,radial,high-order axial,and high-order radial oscillations.展开更多
A facile approach was successfully employed to prepare Fe_(2)O_(3)/Co_(3)O_(4)nanosheet arrays on nickel foams(Fe_(2)O_(3)/Co_(3)O_(4)@NF),which owned such advantages as narrow band gap energies and high separation ra...A facile approach was successfully employed to prepare Fe_(2)O_(3)/Co_(3)O_(4)nanosheet arrays on nickel foams(Fe_(2)O_(3)/Co_(3)O_(4)@NF),which owned such advantages as narrow band gap energies and high separation rate of photoexcited electron-hole pairs.The combination of Fe_(2)O_(3)and Co_(3)O_(4)dramatically enhanced the photocatalytic activity towards sulfamethoxazole(SMZ)degradation,with the highest catalytic efficiency of k=0.0538 min^(−1),which was much higher than that of Fe_(2)O_(3)@NF(0.0098 min^(−1))and Co_(3)O_(4)@NF(0.0094 min^(−1)).The introduction of Ni foam could not only act as the support to anchor photocatalyst,but also work as the electron mediator to promote the transition of electron-hole pairs.Reactive species trapping experiments combined with electron paramagnetic resonance analysis confirmed^(·)O^(-)_(2)−was primarily responsible for SMZ degradation.Furthermore,Fe_(2)O_(3)/Co_(3)O_(4)@NF was effective and almost unaffected by inorganic cations and anions in aqueous solution.This study could provide a facile and promising path for the construction of self-supported metal oxide-based heterojunction with high efficiency and strong stability.展开更多
Environmental risks posed by discharge of the emerging contaminant antimony(Sb) into water bodies have raised global concerns recently.The toxicity of Sb has been shown to be species-dependent,with Sb(Ⅲ) demonstratin...Environmental risks posed by discharge of the emerging contaminant antimony(Sb) into water bodies have raised global concerns recently.The toxicity of Sb has been shown to be species-dependent,with Sb(Ⅲ) demonstrating much greater toxicity than Sb(V).Here,we proposed an electrochemical filtration system to achieve rapid detoxification of Sb(Ⅲ) via a non-radical pathway.The key to this technology was an electroactive carbon nanotube filter functionalized with nanoscale Ti-Ce binary oxide.Under an electric field,in situ generated H_(2) O_(2) could react with the Ti-Ce binary oxide to produce hydroperoxide complexes,which enabled an efficient transformation of Sb(Ⅲ) to the less toxic Sb(V)(τ<2 s) at neutral pH.The impact of important operational parameters was assessed and optimized,and system efficacy could be maintained over a wide pH range and long-term operation.An optimum detoxification efficiency of> 90% was achieved using lake water spiked with Sb(Ⅲ) at 500 μg/L.The results showed that Ti/Ce-hydroperoxo surface complexes were the dominant species responsible for the non-radical oxidation of Sb(Ⅲ) based on extensive experimental evidences and advanced characterizations.This study provides a robust and effective strategy for the detoxification of water containing Sb(Ⅲ) and other similar heavy metal ions by integrating state-of-the-art advanced oxidation processes,electrochemistry and nano-filtration technology.展开更多
基金supported by the National Natural Science Foundation of China(No.22072064,51522805,51908273,and 22176086)the State Key Laboratory of Pollution Control and Resource Reuse(PCRR-ZZ-202106)Start-Up Funds for Jiangsu Distinguished Professor.
文摘The low intrinsic activity of Fenton catalytic site and high demand for light-energy input inhibit the organic-pollution control efficiency of photo-Fenton process.Here,through structural design with density functional theory(DFT)calculations,Ce is predicted to enable the construction of coordinatively unsaturated metal centers(CUCs)in Prussian blue analogue(PBA),which can strongly adsorb H_(2)O_(2)and donate sufficient electrons for directly splitting the O-O bond to produceOH.Using a substitution-co-assembly strategy,binary Ce-Fe PBA is then prepared,which rapidly degrades sulfamethoxazole with the pseudo-first-order kinetic rate constant exceeding reported values by 1-2 orders of magnitude.Meanwhile,the photogenerated electrons reduce Fe(Ⅲ)and Ce(Ⅳ)to promote the metal valence cycle in CUCs and make sulfamethoxazole degradation efficiency only lose 6.04%in 5 runs.Overall,by introducing rare earth metals into transition metal-organic frameworks,this work guides the whole process for highly active CUCs from design and construction to mechanism exploration with DFT calculations,enabling ultrafast and stable photo-Fenton catalysis.
基金supported in part by the National Natural Science Foundation of China(62171322,62006173)the 2021-2023 China-Serbia Inter-Governmental S&T Cooperation Project(No.6)+1 种基金support of the Sino-German Center of Intelligent Systems,Tongji University。
文摘In highly dynamic and heterogeneous vehicular communication networks,it is challenging to efficiently utilize network resources and ensure demanding performance requirements of safetyrelated applications.This paper investigates machinelearning-assisted transmission design in a typical multi-user vehicle-to-vehicle(V2V)communication scenario.The transmission process proceeds sequentially along the discrete time steps,where several source nodes intend to deliver multiple different types of messages to their respective destinations within the same spectrum.Due to rapid movement of vehicles,real-time acquirement of channel knowledge and central coordination of all transmission actions are in general hard to realize.We consider applying multi-agent deep reinforcement learning(MADRL)to handle this issue.By transforming the transmission design problem into a stochastic game,a multi-agent proximal policy optimization(MAPPO)algorithm under a centralized training and decentralized execution framework is proposed such that each source decides its own transmission message type,power level,and data rate,based on local observations of the environment and feedback,to maximize its energy efficiency.Via simulations we show that our method achieves better performance over conventional methods.
基金This study was supported in part by the Funding of Science for Earthquake Resilience(Grant Nos.XH20057,XH21034,XH21036Y)the National Natural Science Foundation of China(Nos.51778590,51408567)+1 种基金the grant of the Fundamental Research Funding for the Institute of Earthquake Forecasting,China Earthquake Administration(Grant Nos.2018IESLZ06,2016IESLZ01)the Science and Technology Projects Funding for Lanzhou City(Grant No.2018-1-123).
文摘To effectively improve the poor engineering properties of loess and enhance its seismic performance,the industrial by-product lignin is used as a modified material.Based on lots of dynamic triaxial tests,the dynamic elastic modulus and damping ratio of lignin-modified loess were tested.The effects of lignin content on the dynamic elastic modulus and damping ratio of lignin-modified loess were analyzed.Combined with scanning electron microscopy(SEM)and X-ray diffraction(XRD),the microscopic mechanism of lignin to improve the dynamic properties of loess was studied.The results show that lignin can effectively modify the dynamic deformation of loess under dynamic load.Under the same dynamic stress condition,the dynamic strain of lignin-modified loess is smaller than compacted loess.The dynamic elastic modulus of modified loess with different lignin content are quite different,but both decrease with the increase of dynamic strain.And the dynamic elastic modulus of modified loess is greater than compacted loess.The maximum dynamic elastic modulus of modified loess with a lignin content of 1%are significantly greater than others.Under the same dynamic strain condition,the damping ratio of lignin-modified loess is smaller than compacted loess.Lignin can effectively fill loess pores and cement loess particles.Compared with compacted loess,no new mineral components are generated in the lignin-modified loess.The optimum lignin content of dynamics characteristic of modified loess is present,and the optimum lignin content is 1%.
基金the support provided by the National Natural Science Foundation of China(No.51522805)。
文摘Heavy metals usually exist stably as the species of organic complexes in high-salinity wastewater.Therefore,their effective removal is challenging,especially when the initial p H is neutral.Herein,a novel nitrogen doped biomass-based composite(N-CMCS)was synthesized to remove the complexed heavy metal of Cr(Ⅲ)-carboxyl.The maximum adsorption capacity of Cr(Ⅲ)-Citrate(Cr-Cit)by N-CMCS under neutral p H(7.0)and high-salinity(200 mmol/L NaCl)condition was up to 2.50 mmol/g.And the removal performance remained stable after 6 times of regeneration.Combined with species and characterizations analysis,electrostatic attraction and hydrogen bonding were the main mechanisms for N-CMCS to remove Cr(Ⅲ)-carboxyl complexes.Dynamic adsorption indicated N-CMCS column could treat about 1300BV simulated wastewater and 350 BV actual wastewater with the concentration of effluent lower than1.0 mg/L.Furthermore,N-CMCS could remove a variety of complexed heavy metal ions under neutral p H,indicating the great potential in practical application.
基金support from the China Postdoctoral Science Foundation(2022M711553).Y.W.would like to acknowledge the support from the National Natural Science Foundation of China(22171132)the Innovation Fund from Nanjing University(020514913419)+5 种基金the Program for Innovative Talents and Entrepreneurs in Jiangsu(020513006012 and 020513006014),and the National Key R&D Program of China(2002YFB3607000).W.Z.would like to acknowledge the support from the National Natural Science Foundation of China(22176086)Natural Science Foundation of Jiangsu Province(BK20210189)State Key Laboratory of Pollution Control and Resource Reuse(PCRR-ZZ-202106)the Fundamental Research Funds for the Central Universities(021114380183,021114380189 and 021114380199)the Research Funds from the Nanjing Science and Technology Innovation Project for Chinese Scholars Studying Abroad(13006003)the Research Funds from Frontiers Science Center for Critical Earth Material Cycling of Nanjing University,and Research Funds for Jiangsu Distinguished Professor.Y.L.would like to thank the support from the Washington State University startup fund.
文摘Non-precious metal single-atom catalysts(NPM-SACs)with unique electronic structures and coordination environments have gained much attention in electrocatalysis owing to their low cost,high atomic utilization,and high performance.NPM-SACs on carbon support(NPM-SACs/CS)are promising because of the carbon substrate with a large surface area,excellent electrical conductivity,and high chemical stability.This review provides an overview of recent developments in NPM-SACs/CS for the electrocatalytic field.First,the state-of-the-art synthesis methods and advanced characterization techniques of NPM-SACs/CS are discussed in detail.Then,the structural adjustment strategy of NPM-SACs/CS for optimizing electrocatalytic performance is introduced concisely.Furthermore,we provide a comprehensive summary of recent advances in developing NPM-SACs/CS for important electrochemical reactions,including carbon dioxide reduction reaction,hydrogen evolution reaction,oxygen evolution reaction,oxygen reduction reaction,and nitrogen reduction reaction.In the end,the existing challenges and future opportunities of NPM-SACs/CS in the electrocatalytic field are highlighted.
基金supported by the National Natural Science Foundation of China(No.52170068 and U21A20161)the Open Project of State Key Laboratory of Urban Water Resource and Environment,Harbin Institute of Technology(No.QAK202108).
文摘Per- and polyfluoroalkyl substances (PFAS) pose serious human health and environmental risks due to their persistence and toxicity. Among the available PFAS remediation options, the electrochemical approach is promising with better control. In this review, recent advances in the decontamination of PFAS from water using several state-of-the-art electrochemical strategies, including electro-oxidation, electro-adsorption, and electro-coagulation, were systematically reviewed. We aimed to elucidate their design principles, underlying working mechanisms, and the effects of operation factors (e.g., solution pH, applied voltage, and reactor configuration). The recent developments of innovative electrochemical systems and novel electrode materials were highlighted. In addition, the development of coupled processes that could overcome the shortcomings of low efficiency and high energy consumption of conventional electrochemical systems was also emphasized. This review identified several major knowledge gaps and challenges in the scalability and adaptability of efficient electrochemical systems for PFAS remediation. Materials science and system design developments are forging a path toward sustainable treatment of PFAS-contaminated water through electrochemical technologies.
文摘The influences of dewatered sludge blending ratio in coal on flammability index (C) and combustion characteristic index (S) and release of sulfur dioxide (SO2), nitrogen oxide (NOx), carbon monoxide (CO) and heavy metals (Hg, As, Cd, Pb and Cr) were studied. The impact on combustion characteristics could be ignored if less than 20% of dewatered sludge was added in coal. Besides, emission pattern experiments of NOx, SO2, CO and heavy metals were carried out in a high-temperature tubular furnace. Results showed that the conversion rate of NOx and total emission of SO2 reduced with the increase of sludge adding ratio, and a better effect of fixing sulfur could be obtained when the blending ratio reached 30%. Concentrations and distributions of five types of heavy metals in different residues (bottom ash and fly ash) as well as in flue gas were analyzed. It was shown that the characteristics of coal and sludge, as well as the volatilization of heavy metals had a great influence on the distribution of heavy metals.
基金the Natural Science Foundation of Shanghai,China(No.18ZR1401000)the Shanghai Pujiang Program(No.18PJ1400400)Donghua University for the start-up grant(No.113-07-005710)。
文摘Global climate change,growing population,and environmental pollution underscore the need for a greater focus on providing advanced water treatment technologies.Although electrochemical basedprocesses are becoming promising solutions,they still face challenges owing to mass transport and upscaling which hinder the exploitation of this technology.Electrode design and reactor configuration are key factors for achieving operational improvements.The electroactive membrane has proven to be a breakthrough technology integrating electrochemistry and membrane separation with an enhanced mass transport by convection.In this review article,we discuss recent progress in environmental applications of electroactive membranes with particular focus on those composed of carbon nanotubes(CNT)due to their intriguing physicochemical prope rties.Their applications in degradation of refractory contaminants,detoxification and sequestration of toxic heavy metal ions,and membrane fouling alleviations are systematically reviewed.We then discuss the existing limitations and opportunities for future research.The development of advanced electroactive systems depends on interdisciplinary collaborations in the areas of materials,electrochemistry,membrane development,and environmental sciences.
基金Supported by the National Key Basic Research and Development (973) Program of China (No. 2011CB302700)the National Natural Science Foundation of China (Nos. 61171102,61132001, and 61001118)
文摘A large proportion of Internet of Things (loT) applications are internally publish/subscribe in nature, and traditional architecture cannot support them efficiently and flexibly. In essence, supporting efficient publish/subscribe systems requires data-oriented naming and efficient multicast. Since deployment of native IP-based multicast has failed, overlay-based multicast has become the practical choice. Since load balancing between heterogeneous nodes is an important issue, designing an optimal load balancing overlay net- work for publish/subscribe systems is a necessary endeavor. This study focuses on the optimal load balancing overlay design problem for topic-based publish/subscribe systems in a heterogeneous environment (in terms of node processing power, bandwidth, and reachability). The Minimum Idle Degree (MID) model is introduced to capture the heterogeneity of overlay nodes. Based on the MID model, new node load measures are defined that can accommodate heterogeneous server capacities and capture the node load in publish/subscribe systems more accurately than traditional measures. A new optimization problem, Maximum Minimum Idle Degree Topic-Connected Overlay (MMID-TCO), is established. This problem is NP-complete and a constant approximation algorithm does not exist for this problem (unless P=NP). Based on MID metrics, the Maximum Minimum Idle Degree Overlay Design Algorithm (MMID-ODA), which has polynomial time is introduced. To improve performance, an approach that breaks down the problem into several small-scale problems by exploiting the potential inherent disjoint characteristic in the subscription table is presented. Simulation results show that the proposed algorithm is able to achieve better load balance than MinMax-ODA in a heterogeneous environment.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.62003060,51975070 and 62033001)the National Key Research and Development Program of China under Grant 2020YFB1313000.
文摘As the essential technology of human-robotics interactive wearable devices,the robotic knee prosthesis can provide above-knee amputations with functional knee compensations to realize their physical and psychological social regression.With the development of mechanical and mechatronic science and technology,the fully active knee prosthesis that can provide subjects with actuating torques has demonstrated a better wearing performance in slope walking and stair ascent when compared with the passive and the semi-active ones.Additionally,with intelligent human-robotics control strategies and algorithms,the wearing effect of the knee prosthesis has been greatly enhanced in terms of stance stability and swing mobility.Therefore,to help readers to obtain an overview of recent progress in robotic knee prosthesis,this paper systematically categorized knee prostheses according to their integrated functions and introduced related research in the past ten years(2010−2020)regarding(1)mechanical design,including uniaxial,four-bar,and multi-bar knee structures,(2)actuating technology,including rigid and elastic actuation,and(3)control method,including mode identification,motion prediction,and automatic control.Quantitative and qualitative analysis and comparison of robotic knee prosthesis-related techniques are conducted.The development trends are concluded as follows:(1)bionic and lightweight structures with better mechanical performance,(2)bionic elastic actuation with energy-saving effect,(3)artificial intelligence-based bionic prosthetic control.Besides,challenges and innovative insights of customized lightweight bionic knee joint structure,highly efficient compact bionic actuation,and personalized daily multi-mode gait adaptation are also discussed in-depth to facilitate the future development of the robotic knee prosthesis.
基金supported by the National Natural Science Foundation of China(Nos.51878334,51522805)the Natural Science Foundation of Jiangsu Province,China(No.BK20170647)。
文摘A self-synthesized bi-pyridine chelating resin(PAPY)could separate Cu(Ⅱ)/Ni(Ⅱ)/Fe(Ⅱ)sequentially from strong-acidic pickling wastewater by a two-stage p H-adjusted process,in which Cu(Ⅱ),Ni(Ⅱ),and Fe(Ⅱ)were successively preferred by PAPY.In the first stage(p H 1.0),the separation factor of Cu(Ⅱ)over Ni(Ⅱ)reached 61.43 in Cu(Ⅱ)-Ni(Ⅱ)-Fe(Ⅱ)systems.In the second stage(p H 2.0),the separation factor of Ni(Ⅱ)over Fe(Ⅱ)reached 92.82 in Ni(Ⅱ)-Fe(Ⅱ)systems.Emphasis was placed on the selective separation of Cu(Ⅱ)and Ni(Ⅱ)in the first-stage.The adsorption amounts of Cu(Ⅱ)onto PAPY were 1.2 mmol/g in the first stage,while those of Ni(Ⅱ)and Fe(Ⅱ)were lower than 0.3 mmol/g.Cu(Ⅱ)adsorption was hardly affected by Ni(Ⅱ)with the presence of dense Fe(Ⅱ),but Cu(Ⅱ)inhibited Ni(Ⅱ)adsorption strongly.Part of preloaded Ni(Ⅱ)could be replaced by Cu(Ⅱ)based on the replacement effect.Compared with the absence of Fe(Ⅱ),dense Fe(Ⅱ)could obviously enhance the separation of Cu(Ⅱ)-Ni(Ⅱ).More than 95.0%of Cu(Ⅱ)could be removed in the former 240 BV(BV for bed volume of the adsorbent)in the fixed-bed adsorption column process with the flow rate of 2.5 BV/h.As proved by X-ray photoelectron spectrometry(XPS)and density functional theory(DFT)analyses,Cu(Ⅱ)exerted a much stronger deprotonation and chelation ability toward PAPY than Ni(Ⅱ)and Fe(Ⅱ).Thus,the work shows a great potential in the separation and purification of heavy metal resources from strong-acidic pickling wastewaters.
基金generous support provided by the National Natural Science Foundation of China (Nos. 51378253 and 51522805)the Discipline Crossing Foundation of Nanjing University
文摘An efficient and profitable separation process was proposed to prepare 5N (the purity of the metal solution reaches 99.999%) high-purity nickel from 3N nickel-solutions using Purolite S984. The adsorption performance of this superior resin, especially its selectivity for metal ions, was explored quantitatively. The maximum adsorption capacity for copper was 2.286 mmol/g calculated by the Langmuir model, which was twice as large as that for nickel. In the binary systems, the adsorption capacity for nickel was decreased by 45%, indicating direct competition for the active sites. The infinite separation factor for copper versus nickel exceeded 300, revealing the feasibility of preparing 5N-level high-purity nickel solutions, which was further verified using the 800 BV (bed volume) effluent in the column dynamic process. According to the cost-benefit analysis, purification contributed to a profit of approximately 60,000 USD per cycle, and the investment return period was less than 1/3 years. Density functional theory analysis confirmed that four nitrogen atoms would be involved in the coordination complex and thus a structure involving two five-membered rings could be achieved. The X-ray photoelectron spectra confirmed the involvement of nitrogen atoms, implying a coordination ratio of approximately 1:1.
基金We thank the colleagues from the Chinese National Influenza Center,who isolated and sequenced the full genome of A/Hunan/11173/2020(H9N2).
文摘Jishou Municipal Center for Disease Control and Prevention(Jishou CDC)received a phone call at 7:30 a.m.on April 24,2020 from Xiangxi Tujia and Miao Autonomous Prefectural CDC(Xiangxi CDC)that avian influenza A/H9N2 virus was detected by quantitative reverse transcription-polymerase chain reaction(RT-PCR)from the throat swab sample of an influenza-like illness in an outpatient in the Xiangxi Traditional Chinese Medicine Hospital.
基金supported by National Science and Technology Major Project (Nos. 2017-Ⅲ-0007-0032 and J2019-Ⅲ-00020045)
文摘Lean Blow Out(LBO)poses a significant safety hazard when occurring in aero-engines.Understanding the lower stability limits of gas turbine combustors and the characteristics of spray flame close to LBO are imperative for safe operation.The objective of this work is to evaluate the effects of fuel decreasing rates and pressure drops of the injector on LBO performances in a multiswirl staged combustor equipped with an airblast injector.A set of hardware and control system was developed to realize a user-defined fuel supply law.High-speed imaging was applied to record complete LBO processes under the conditions of linear fuel reduction and stable airflow.Partical Image Velocimetry(PIV)and Planar Mie(PMie)scattering were used to acquire the flow fields and spray fields under non-reacting conditions.Experimental results have shown that LBO limits extend to leaner conditions as the pressure drop of the injector increases.With an increase of the fuel decreasing rate,the exhaust temperature before flame extinction increases,and the LBO Fuel-to-Air-Ratio(FAR)decreases.The time evolution of the integral CH*intensity conforms to a linear function during the LBO process.Proper Orthogonal Decomposition(POD)was used to analyze the dynamic characteristics of lean-burn flames.Under different fuel decreasing rates and pressure drops of the injector,flames close to LBO present similar modal spatial distributions,alternately appearing axial,radial,high-order axial,and high-order radial oscillations.
基金the support of Postdoctoral Science Foundation of Jiangsu Province(No.2020Z299)China Postdoctoral Science Foundation(No.2020M671443).
文摘A facile approach was successfully employed to prepare Fe_(2)O_(3)/Co_(3)O_(4)nanosheet arrays on nickel foams(Fe_(2)O_(3)/Co_(3)O_(4)@NF),which owned such advantages as narrow band gap energies and high separation rate of photoexcited electron-hole pairs.The combination of Fe_(2)O_(3)and Co_(3)O_(4)dramatically enhanced the photocatalytic activity towards sulfamethoxazole(SMZ)degradation,with the highest catalytic efficiency of k=0.0538 min^(−1),which was much higher than that of Fe_(2)O_(3)@NF(0.0098 min^(−1))and Co_(3)O_(4)@NF(0.0094 min^(−1)).The introduction of Ni foam could not only act as the support to anchor photocatalyst,but also work as the electron mediator to promote the transition of electron-hole pairs.Reactive species trapping experiments combined with electron paramagnetic resonance analysis confirmed^(·)O^(-)_(2)−was primarily responsible for SMZ degradation.Furthermore,Fe_(2)O_(3)/Co_(3)O_(4)@NF was effective and almost unaffected by inorganic cations and anions in aqueous solution.This study could provide a facile and promising path for the construction of self-supported metal oxide-based heterojunction with high efficiency and strong stability.
基金supported by the Natural Science Foundation of Shanghai,China (No.18ZR1401000)。
文摘Environmental risks posed by discharge of the emerging contaminant antimony(Sb) into water bodies have raised global concerns recently.The toxicity of Sb has been shown to be species-dependent,with Sb(Ⅲ) demonstrating much greater toxicity than Sb(V).Here,we proposed an electrochemical filtration system to achieve rapid detoxification of Sb(Ⅲ) via a non-radical pathway.The key to this technology was an electroactive carbon nanotube filter functionalized with nanoscale Ti-Ce binary oxide.Under an electric field,in situ generated H_(2) O_(2) could react with the Ti-Ce binary oxide to produce hydroperoxide complexes,which enabled an efficient transformation of Sb(Ⅲ) to the less toxic Sb(V)(τ<2 s) at neutral pH.The impact of important operational parameters was assessed and optimized,and system efficacy could be maintained over a wide pH range and long-term operation.An optimum detoxification efficiency of> 90% was achieved using lake water spiked with Sb(Ⅲ) at 500 μg/L.The results showed that Ti/Ce-hydroperoxo surface complexes were the dominant species responsible for the non-radical oxidation of Sb(Ⅲ) based on extensive experimental evidences and advanced characterizations.This study provides a robust and effective strategy for the detoxification of water containing Sb(Ⅲ) and other similar heavy metal ions by integrating state-of-the-art advanced oxidation processes,electrochemistry and nano-filtration technology.