Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a...Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a specific habit plane owing to the constraint of free-energy minimization of the system.Herein,in an aged ultralight Mg-Li-Zn alloy,we confirmed that the precipitates dominated by C15 Laves structure could form in a variety of habit planes,to generate three forms of strengthening-phases,i.e.,precipitate-rod,precipitate-lath,and precipitate-plate.Among which,the precipitate-plates are on basal plane as usually but precipitate-rods/laths are on non-basal plane,and such non-basal precipitates would transform into the basal(Mg,Li)Zn_(2)Laves structure with prolonged aging.These findings are interesting to understand the precipitation behaviors of multi-domain Laves structures in hexagonal close-packed crystals,and expected to provide a guidance for designing ultralight high-strength Mg-Li based alloys via precipitation hardening on the non-basal planes.展开更多
To prevent the thawing of ice-rich permafrost,it is suggested that gas should be transported in a chilled state(below the freezing temperature)in pipelines buried in permafrost.However,frost heave occurs when water mi...To prevent the thawing of ice-rich permafrost,it is suggested that gas should be transported in a chilled state(below the freezing temperature)in pipelines buried in permafrost.However,frost heave occurs when water migrates towards the chilled pipeline and ice lenses grow underneath the pipe.This might endanger the integrity of the pipeline and the environment as well.Therefore,innovative frost heave mitigation measures are required when designing the pipeline,especially those sections in discontinuous permafrost or near the compressor stations.The ground temperature field in response to the operation of a proposed chilled gas pipeline traversing permafrost regions in Alaska was simulated by a pipe-soil thermal interaction geothermal model.Frost heave mitigation measures,including insulation around the pipe,flat slab insulation under the pipe,and heating cables combined with slab insulation,were evaluated for chilled pipeline operation in seasonally varying ambient temperatures.The numerical results show that the minimum temperature of the observation point at 2.5 m below the pipe bottom increases by 17%,29%,and 48%when the thermal conductivity of the outer insulation layer is 0.1,0.05,and 0.02 W/(m K),respectively.For flat slab insulation,the thermal field is less sensitive to varying slab thicknesses than to varying thermal conductivity,implying the thermal conductivity,not the thickness,is the crucial factor.Additionally,the heat flow could be redirected from vertical to horizontal by flat slab insulation.The electrical heating cables could be regarded as a new heat source to balance the heat removal rate of the soil around the chilled pipe.The minimum temperature of the observation point at 1.1 m below the bottom of the pipe increases from-15.2℃to-3.0,1.5,and 7.5℃,corresponding to the heating cable power of 20,30,and 40 W,respectively,with the power of 30 W deemed appropriate for the study case.It is concluded that heating cables in combination with insulation slabs could be adopted to regulate the temperature field around the chilled pipeline efficiently and economically.The advantages of this combination include redirecting the heat flow and eliminating frost in the soil underlying the pipe.These approaches could be considered for applications in gas pipeline projects in arctic and alpine/high-plateau permafrost regions.展开更多
Single-atom photocatalysts(SAPCs)have attracted great interests due to their remarkable atom utilization efficiency,excellent activity,and selectivity,yet no application in synchronous biorefinery and water splitting....Single-atom photocatalysts(SAPCs)have attracted great interests due to their remarkable atom utilization efficiency,excellent activity,and selectivity,yet no application in synchronous biorefinery and water splitting.Here,efficient SAPCs based on atomically dispersed Zn atoms on carbon nitride(named Zn-mCN)were produced.Experiments verified that Zn-mCN has widened adsorption range of visible-light and lowered ability of electron-hole recombination,leading to excellent photocatalytic redox activity for synchronous biorefinery and water splitting to co-produce lactic acid(selectivity up to 91.0%)and hydrogen(-15898.8μmolg^(-1)h^(-1)).This system has excellent universality for small-molecule monosaccharides and macromolecular xylan.Poisoning experiments showed that h^(+),1O2,·O_(2)-and·OH can promote the simultaneous production of lactic acid and hydrogen.This work realized full utilization of whole redox reaction and provided a novel strategy for efficient and concomitant production of hydrogen and value-added chemicals from biomass-derived feedstocks aqueous solutions.展开更多
The droplet deposition is a key index to evaluate the quality of unmanned aerial vehicle(UAV)spraying.The detection of the droplet deposition is time-consuming and costly,therefore,it is difficult to achieve large-sca...The droplet deposition is a key index to evaluate the quality of unmanned aerial vehicle(UAV)spraying.The detection of the droplet deposition is time-consuming and costly,therefore,it is difficult to achieve large-scale and rapid acquisition in the field.To solve the above problems,a droplet deposition acquisition system(DDAS)was developed.It was composed of the multiple sensors,processing units,remote server database and Android-based software.A droplet deposition prediction model based on field experimental data was established by using a one-dimensional convolutional neural network(1D-CNN)algorithm,and the effects of different inputs on the prediction ability of the model were analyzed.The results showed that adding temperature and humidity data to the inputs can achieve higher prediction accuracy than only using UAV spraying operation parameters and wind speed data as the inputs to the model.In addition,the prediction accuracy of the 1D-CNN model was the highest when compared with other models such as back propagation neural network,multiple correlation vector machine,and multiple linear regression.The 1D-CNN model was embedded into the DDAS,and the evaluation experiments were carried out in the field.The correlation analysis was conducted between two datasets of the droplet deposition obtained by the DDAS and water sensitive paper(WSP),respectively.The R2 was 0.924,and the RMSE was 0.026μL/cm2.It is proved that the droplet deposition values obtained by the DDAS and WSP have high consistency,and the DDAS developed can provide an auxiliary solution for the intelligent evaluation of UAV spraying quality.展开更多
Residual magnetic error remains after standard levelling process.The weak non-geological effect,manifesting itself as streaky noise along flight lines,creates a challenge for airborne geophysical data processing and i...Residual magnetic error remains after standard levelling process.The weak non-geological effect,manifesting itself as streaky noise along flight lines,creates a challenge for airborne geophysical data processing and interpretation.Microleveling is the process to eliminate this residual noise and is now a standard areogeophysical data processing step.In this paper,we propose a two-step procedure for single aerogeophysical data microleveling:a deep convolutional network is first adopted as approximator to map the original data into a low-level part with nature geological structures and a corrugated residual which still contains high-level detail geological structures;second,the mixture of Gaussian robust principal component analysis(MoG-RPCA)is then used to separate the weak energy fine structures from the residual.The final microleveling result is the addition of low-level structures from deep convolutional network and fine structures from MoG-RPCA.The deep convolutional network does not need dataset for training and the handcrafted network serves as prior(deep image prior)to capture the low-level nature geological structures in the areogeophysical data.Experiments on synthetic data and field data demonstrate that the combination of deep convolutional network and MoG-RPCA is an effective framework for single areogeophysical data microleveling.展开更多
To solve the problem of lacking scientific guidance in aerial pesticide application,this study introduced an adaptive spraying decision system(ASDS)for Unmanned Aerial Vehicle(UAV)spraying to guide the operators of pl...To solve the problem of lacking scientific guidance in aerial pesticide application,this study introduced an adaptive spraying decision system(ASDS)for Unmanned Aerial Vehicle(UAV)spraying to guide the operators of plant protection UAVs to set reasonable spraying parameters under complicated environment.The minimum applied volume rate,proper spraying velocity,spraying height,and initial droplet size were recommended by the ASDS.The key factor of the decision system is the decision model of reinforcement learning based on the actor-critic neural network.In specific,the field experimental data were used to train the critic and actor networks,which made the model adaptive to optimize the output of spraying parameters.Compared with the conventional spraying parameters,the spraying parameters recommended by the ASDS had a positive impact on wheat parcels.The decision results of the ASDS showed that the spraying volume rate was lower in the blocks with a small leaf area index.In addition,the spraying volume rate for the whole parcel was reduced by 14%.After UAV spraying,the uniformity of the droplet deposition in the ASDS parcel was better than that in the conventional parcel.Moreover,the penetrability of the droplets and the control efficacy for the brown wheat mite Petrobia latens(Muller)were similar in the two parcels.The ASDS can recommend the optimal spraying parameters to minimize pesticide application.展开更多
Extracellular vesicles(EVs)are nanoscale substances produced by most cells,which were not fully understood in the early years.However,with the development of advanced techniques,researchers have discovered that EVs pl...Extracellular vesicles(EVs)are nanoscale substances produced by most cells,which were not fully understood in the early years.However,with the development of advanced techniques,researchers have discovered that EVs play an essential role in information exchange and signal transduction between cells.Nowadays,EVs are being used,modified,and developed as a natural drug carrier in various medical fields because of their high biocompatibility and natural affinity with the source body.Many studies have shown that multiple sources of EVs have been modified and utilized in cancer therapy to improve patients’treatment windows and effectively prolong patient survival.In this paper,we review the advances in the treatment of cancer based on EVs.We summarize the types of EVs loading therapy,the modes of drug loading and the latest therapeutic applications of multiple modes combined with EVs in cancer treatment.We conclude with a discussion of the current status,challenges,and prospects of EVs as a tool for tumor therapy.展开更多
基金the National Natural Science Foundation of China(Grant No.51525101,No.51971053,No.52101129)the Project of Promoting Talents in Liaoning Province(No.XLYC1808038)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.N2002018)the Project funded by China Postdoctoral Science Foundation(2020M670774)。
文摘Precipitation habits plays a decisive role in strengthening materials,especially for Mg alloys the non-basal plane precipitation is necessary but very limited.Generally,the precipitates would nucleate and grow up in a specific habit plane owing to the constraint of free-energy minimization of the system.Herein,in an aged ultralight Mg-Li-Zn alloy,we confirmed that the precipitates dominated by C15 Laves structure could form in a variety of habit planes,to generate three forms of strengthening-phases,i.e.,precipitate-rod,precipitate-lath,and precipitate-plate.Among which,the precipitate-plates are on basal plane as usually but precipitate-rods/laths are on non-basal plane,and such non-basal precipitates would transform into the basal(Mg,Li)Zn_(2)Laves structure with prolonged aging.These findings are interesting to understand the precipitation behaviors of multi-domain Laves structures in hexagonal close-packed crystals,and expected to provide a guidance for designing ultralight high-strength Mg-Li based alloys via precipitation hardening on the non-basal planes.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20100103).
文摘To prevent the thawing of ice-rich permafrost,it is suggested that gas should be transported in a chilled state(below the freezing temperature)in pipelines buried in permafrost.However,frost heave occurs when water migrates towards the chilled pipeline and ice lenses grow underneath the pipe.This might endanger the integrity of the pipeline and the environment as well.Therefore,innovative frost heave mitigation measures are required when designing the pipeline,especially those sections in discontinuous permafrost or near the compressor stations.The ground temperature field in response to the operation of a proposed chilled gas pipeline traversing permafrost regions in Alaska was simulated by a pipe-soil thermal interaction geothermal model.Frost heave mitigation measures,including insulation around the pipe,flat slab insulation under the pipe,and heating cables combined with slab insulation,were evaluated for chilled pipeline operation in seasonally varying ambient temperatures.The numerical results show that the minimum temperature of the observation point at 2.5 m below the pipe bottom increases by 17%,29%,and 48%when the thermal conductivity of the outer insulation layer is 0.1,0.05,and 0.02 W/(m K),respectively.For flat slab insulation,the thermal field is less sensitive to varying slab thicknesses than to varying thermal conductivity,implying the thermal conductivity,not the thickness,is the crucial factor.Additionally,the heat flow could be redirected from vertical to horizontal by flat slab insulation.The electrical heating cables could be regarded as a new heat source to balance the heat removal rate of the soil around the chilled pipe.The minimum temperature of the observation point at 1.1 m below the bottom of the pipe increases from-15.2℃to-3.0,1.5,and 7.5℃,corresponding to the heating cable power of 20,30,and 40 W,respectively,with the power of 30 W deemed appropriate for the study case.It is concluded that heating cables in combination with insulation slabs could be adopted to regulate the temperature field around the chilled pipeline efficiently and economically.The advantages of this combination include redirecting the heat flow and eliminating frost in the soil underlying the pipe.These approaches could be considered for applications in gas pipeline projects in arctic and alpine/high-plateau permafrost regions.
基金supported by the National Natural Science Foundation of China(No.22008018)China Postdoctoral Science Foundation(No.2020M670716)+5 种基金the Natural Science Foundation of Liaoning Province,China(No.2020-MS-272)the Foundation of Guangxi Key Laboratory of Clean Pulp&Papermaking and Pollution Control,College of Light Industry and Food Engineering,Guangxi University(No.2021KF08)Dalian City Outstanding Talent Project(No.2019RD13)the Start-up Fund for Doctoral Research of Dalian Polytechnic University(No.2020–07)the Foundation of State Key Laboratory of Biobased Material and Green Papermaking,Qilu University of Technology,Shandong Academy of Sciences(No.KF201914)the Foundation of Key Laboratory of State Forestry and Grassland Administration for Plant Fiber Functional Materials(No.2020KFJJ06).
文摘Single-atom photocatalysts(SAPCs)have attracted great interests due to their remarkable atom utilization efficiency,excellent activity,and selectivity,yet no application in synchronous biorefinery and water splitting.Here,efficient SAPCs based on atomically dispersed Zn atoms on carbon nitride(named Zn-mCN)were produced.Experiments verified that Zn-mCN has widened adsorption range of visible-light and lowered ability of electron-hole recombination,leading to excellent photocatalytic redox activity for synchronous biorefinery and water splitting to co-produce lactic acid(selectivity up to 91.0%)and hydrogen(-15898.8μmolg^(-1)h^(-1)).This system has excellent universality for small-molecule monosaccharides and macromolecular xylan.Poisoning experiments showed that h^(+),1O2,·O_(2)-and·OH can promote the simultaneous production of lactic acid and hydrogen.This work realized full utilization of whole redox reaction and provided a novel strategy for efficient and concomitant production of hydrogen and value-added chemicals from biomass-derived feedstocks aqueous solutions.
基金the National Key Research and Development Program of China(2019YFE0125500).
文摘The droplet deposition is a key index to evaluate the quality of unmanned aerial vehicle(UAV)spraying.The detection of the droplet deposition is time-consuming and costly,therefore,it is difficult to achieve large-scale and rapid acquisition in the field.To solve the above problems,a droplet deposition acquisition system(DDAS)was developed.It was composed of the multiple sensors,processing units,remote server database and Android-based software.A droplet deposition prediction model based on field experimental data was established by using a one-dimensional convolutional neural network(1D-CNN)algorithm,and the effects of different inputs on the prediction ability of the model were analyzed.The results showed that adding temperature and humidity data to the inputs can achieve higher prediction accuracy than only using UAV spraying operation parameters and wind speed data as the inputs to the model.In addition,the prediction accuracy of the 1D-CNN model was the highest when compared with other models such as back propagation neural network,multiple correlation vector machine,and multiple linear regression.The 1D-CNN model was embedded into the DDAS,and the evaluation experiments were carried out in the field.The correlation analysis was conducted between two datasets of the droplet deposition obtained by the DDAS and water sensitive paper(WSP),respectively.The R2 was 0.924,and the RMSE was 0.026μL/cm2.It is proved that the droplet deposition values obtained by the DDAS and WSP have high consistency,and the DDAS developed can provide an auxiliary solution for the intelligent evaluation of UAV spraying quality.
文摘Residual magnetic error remains after standard levelling process.The weak non-geological effect,manifesting itself as streaky noise along flight lines,creates a challenge for airborne geophysical data processing and interpretation.Microleveling is the process to eliminate this residual noise and is now a standard areogeophysical data processing step.In this paper,we propose a two-step procedure for single aerogeophysical data microleveling:a deep convolutional network is first adopted as approximator to map the original data into a low-level part with nature geological structures and a corrugated residual which still contains high-level detail geological structures;second,the mixture of Gaussian robust principal component analysis(MoG-RPCA)is then used to separate the weak energy fine structures from the residual.The final microleveling result is the addition of low-level structures from deep convolutional network and fine structures from MoG-RPCA.The deep convolutional network does not need dataset for training and the handcrafted network serves as prior(deep image prior)to capture the low-level nature geological structures in the areogeophysical data.Experiments on synthetic data and field data demonstrate that the combination of deep convolutional network and MoG-RPCA is an effective framework for single areogeophysical data microleveling.
基金This study was financially supported by the Chinese National Key Research and Development Plan(Grant No.2019YFE0125500).
文摘To solve the problem of lacking scientific guidance in aerial pesticide application,this study introduced an adaptive spraying decision system(ASDS)for Unmanned Aerial Vehicle(UAV)spraying to guide the operators of plant protection UAVs to set reasonable spraying parameters under complicated environment.The minimum applied volume rate,proper spraying velocity,spraying height,and initial droplet size were recommended by the ASDS.The key factor of the decision system is the decision model of reinforcement learning based on the actor-critic neural network.In specific,the field experimental data were used to train the critic and actor networks,which made the model adaptive to optimize the output of spraying parameters.Compared with the conventional spraying parameters,the spraying parameters recommended by the ASDS had a positive impact on wheat parcels.The decision results of the ASDS showed that the spraying volume rate was lower in the blocks with a small leaf area index.In addition,the spraying volume rate for the whole parcel was reduced by 14%.After UAV spraying,the uniformity of the droplet deposition in the ASDS parcel was better than that in the conventional parcel.Moreover,the penetrability of the droplets and the control efficacy for the brown wheat mite Petrobia latens(Muller)were similar in the two parcels.The ASDS can recommend the optimal spraying parameters to minimize pesticide application.
基金National Key Research and Development Program of China(2022YFE132800)National Natural Science Foundation of China(82101184)+2 种基金Shenzhen Science and Technology Program(JCYJ20210324102809024 and RCBS20210609103713045)Guangdong Basic and Applied Basic Research Foundation(2020A1515110780)Special Foundation for Basic Research Program of Higher Education Institutions of Henan Province(22ZX005).
文摘Extracellular vesicles(EVs)are nanoscale substances produced by most cells,which were not fully understood in the early years.However,with the development of advanced techniques,researchers have discovered that EVs play an essential role in information exchange and signal transduction between cells.Nowadays,EVs are being used,modified,and developed as a natural drug carrier in various medical fields because of their high biocompatibility and natural affinity with the source body.Many studies have shown that multiple sources of EVs have been modified and utilized in cancer therapy to improve patients’treatment windows and effectively prolong patient survival.In this paper,we review the advances in the treatment of cancer based on EVs.We summarize the types of EVs loading therapy,the modes of drug loading and the latest therapeutic applications of multiple modes combined with EVs in cancer treatment.We conclude with a discussion of the current status,challenges,and prospects of EVs as a tool for tumor therapy.
