Monitoring the dynamics of soil salinization is of great importance for agricultural production.This study selected Yucheng County,a typical county on the Huang-Huai-Hai Plain(HHHP)of China,as the study area and evalu...Monitoring the dynamics of soil salinization is of great importance for agricultural production.This study selected Yucheng County,a typical county on the Huang-Huai-Hai Plain(HHHP)of China,as the study area and evaluated the spatial and temporal variation of soil salinization.Three methods,consisting of principal component analysis(PCA)transformation,tasseled cap(TC)transformation,and optimal band combination(OBC),were used to extract information from an early Landsat multispectral scanner(MSS)image from 1984,and their advantages were compared.In addition,OBC was used on a thematic mapper(TM)image from 2009.An iteratively self-organizing data analysis algorithm was used together with prior knowledge of likely classifications to interpret the MSS and TM images for data classification.Finally,a transfer matrix method was used to assess the spatial and temporal variability of soil salinization and analyze the driving factors of soil salinization.Compared to PCA transformation and OBC,TC transformation was a more effective method for extracting soil salinization information from the MSS sensor.The results indicate that a soil area of approximately 298 km^2was affected by salinity in 1984 in Yucheng County,of which 5.40%,11.96%,and 12.75%were classified as being subject to slight,moderate,and severe salinization,respectively.In 2009,the saline area was reduced to only 146 km^2,of which 10.70%and 3.75%were characterized by slight to moderate salinization and no severe salinization,respectively.The saline land decreased at an average rate of 6 km^2per year.This decrease was probably a result of lower groundwater depth,increased organic fertilizer or crop straw in soil,changed land use type,and increased vegetation coverage.展开更多
Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing...Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.展开更多
In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data be...In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data benchmark(HIS)has garnered the most attention due to its practicality and effectiveness.However,existing CPM reviews usually focus on the theoretical benchmark,and there is a lack of an in-depth review that thoroughly explores HIS-based methods.In this article,a comprehensive overview of HIS-based CPM is provided.First,we provide a novel static-dynamic perspective on data-level manifestations of control performance underlying typical controller capacities including regulation and servo:static and dynamic properties.The static property portrays time-independent variability in system output,and the dynamic property describes temporal behavior driven by closed-loop feedback.Accordingly,existing HIS-based CPM approaches and their intrinsic motivations are classified and analyzed from these two perspectives.Specifically,two mainstream solutions for CPM methods are summarized,including static analysis and dynamic analysis,which match data-driven techniques with actual controlling behavior.Furthermore,this paper also points out various opportunities and challenges faced in CPM for modern industry and provides promising directions in the context of artificial intelligence for inspiring future research.展开更多
systematic verification and validation(V&V)of our previously proposed momentum source wave generation method is performed.Some settings of previous numerical wave tanks(NWTs)of regular and irregular waves have bee...systematic verification and validation(V&V)of our previously proposed momentum source wave generation method is performed.Some settings of previous numerical wave tanks(NWTs)of regular and irregular waves have been optimized.The H2-5 V&V method involving five mesh sizes with mesh refinement ratio being 1.225 is used to verify the NWT of regular waves,in which the wave height and mass conservation are mainly considered based on a Lv3(H s=0.75 m)and a Lv6(H s=5 m)regular wave.Additionally,eight different sea states are chosen to validate the wave height,mass conservation and wave frequency of regular waves.Regarding the NWT of irregular waves,five different sea states with significant wave heights ranging from 0.09 m to 12.5 m are selected to validate the statistical characteristics of irregular waves,including the profile of the wave spectrum,peak frequency and significant wave height.Results show that the verification errors for Lv3 and Lv6 regular wave on the most refined grid are−0.018 and−0.35 for wave height,respectively,and−0.14 and for−0.17 mass conservation,respectively.The uncertainty estimation analysis shows that the numerical error could be partially balanced out by the modelling error to achieve a smaller validation error by adjusting the mesh size elaborately.And the validation errors of the wave height,mass conservation and dominant frequency of regular waves under different sea states are no more than 7%,8% and 2%,respectively.For a Lv3(H_(s)=0.75 m)and a Lv6(H_(s)=5 m)regular wave,simulations are validated on the wave height in wave development section for safety factors FS≈1 and FS≈0.5-1,respectively.Regarding irregular waves,the validation errors of the significant wave height and peak frequency are both lower than 2%.展开更多
Numerical simulations were conducted on a 10-blade Sevik rotor ingesting wake downstream of two turbulence-generating grids.These simulations were based on implicit large-eddy simulation(ILES)and the boundary data imm...Numerical simulations were conducted on a 10-blade Sevik rotor ingesting wake downstream of two turbulence-generating grids.These simulations were based on implicit large-eddy simulation(ILES)and the boundary data immersion method(BDIM)for compressible flows,which were solved using a fully self-programmed Fortran code.Results show that the predicted thrust spectrum aligns closely with the experimental measurements.In addition,it captures the thrust dipole directivity of the noise around the rotating propeller due to random pressure pulsations on the blades,as well as the flow structures simultaneously.Furthermore,the differences in the statistical characteristics,flow structures,and low-frequency broadband thrust spectra due to different turbulence levels were investigated.This analysis indicates that the interaction between the upstream,which is characterized by a lower turbulence level and a higher turbulent length of scale,and the rotating propeller results in a lower amplitude in force spectra and a slight increase in the scale of tip vortices.展开更多
In this article,we revisit an article,which specifically focuses on the utilization of exosomes derived from human bone marrow mesenchymal stem cells(MSCs)for targeted delivery of gemcitabine in pancreatic cancer trea...In this article,we revisit an article,which specifically focuses on the utilization of exosomes derived from human bone marrow mesenchymal stem cells(MSCs)for targeted delivery of gemcitabine in pancreatic cancer treatment.The experimental results demonstrated that the exosome-based drug delivery system derived from MSCs significantly augmented apoptosis in pancreatic cancer cells.The biocompatibility,targeting specificity,and low immunogenicity of exosomes render them as optimal carriers for drug delivery,enabling precise administration of therapeutics to diseased tissues while mitigating adverse effects,thereby achieving targeted treatment of cancer cells and significantly enhancing anti-tumor efficacy.However,the clinical application of exosome drug delivery platforms in oncology still presents challenges,necessitating further optimization to ensure their stability and efficacy.This study focuses on elucidating the advantages of exosomes as a drug delivery platform,exploring the utilization of MSC-derived exosomes in oncology therapy,and discussing their potential and future directions in cancer treatment.展开更多
The structural modulation of metal-based heterostructure plays a vital role in achieving enhanced performances for highly efficient electrocatalysis.Here we design submonolayered Ru-modified Pd mesoporous nanosheets(P...The structural modulation of metal-based heterostructure plays a vital role in achieving enhanced performances for highly efficient electrocatalysis.Here we design submonolayered Ru-modified Pd mesoporous nanosheets(Pd-Ru MNSs)with the exposure of both Pd and Ru active sites as well as the high atomic utilization of two-dimensional structure.The obtained Pd-Ru MNSs can act as a highly efficient multifunctional catalyst for hydrogen evolution reaction(HER)and alcohol oxidation reactions including ethylene glycol oxidation(EGOR)and ethanol oxidation(EOR),offering new opportunities towards the alcohol oxidation assisted hydrogen production.Specifically,Pd-Ru MNSs demonstrate excellent HER performance in alkaline electrolyte,requiring an overpotential of only 16mV to reach 10mAcm^(−2),significantly outperforming Pd mesoporous nanosheets and commercial catalysts.Density functional theory calculations reveal that the Ru sites in Pd-Ru MNSs could facilitate the water adsorption,accelerate the water dissociation,and optimize the hydrogen desorption,leading to the superior HER activity.Pd-Ru MNSs also exhibit high mass activities of 11.19 A mg^(−1)Pd for EGOR and 8.84 A mg^(−1)Pd for EOR,which is 7.8 and 9.6 times than that of commercial Pd/C,respectively.The EGOR reaction pathway over Pd-Ru MNSs was further investigated by using in situ Fourier-transform infrared spectroscopy.展开更多
BACKGROUND Depression significantly threatens human health.Purinergic receptors are reported to be associated with depression.However,there is no bibliometric research in this field have been published.AIM To provide ...BACKGROUND Depression significantly threatens human health.Purinergic receptors are reported to be associated with depression.However,there is no bibliometric research in this field have been published.AIM To provide some reference for the further research in the field of purinergic receptors and depression utilizing bibliometric analysis.METHODS Relevant researches were retrieved from the Web of Science Core Collection database.The period of the search was from January 1,2003 to December 31,2023.The CiteSpace(6.2.R7)and VOSviewer(1.6.19)were applied to identify the main contributors of countries,authors,institutions,references and journals.Besides,we evaluate keywords to assess the hotspots and trends over the previous 2 decades.RESULTS Totally,247 articles were identified,showing an increasing trend over time.The most productive country,institution,and journal in this field are China,Harvard University,and Biological Psychiatry,respectively.Liang SD and Rodrigues,Ana Lucia S were the most prolific authors.Burnstock G ranked first among the cited authors.The cooperation among countries and disciplines is crucial.The P2X7 receptor provides promising prospects for treating depression and further studies are warranted to validate the scope and significance of depression therapeutic strategies.CONCLUSION This study provides an overview of the worldwide research status and future trends in purinergic receptors and depression.P2X7 receptor is considered an appropriate target for the treatment of depression,as well as neurological diseases.It is implied that based on purinergic system,the future prospects for interventions aimed at depression treatment are promising,showing the way for both augmentation strategies and new drug treatments in the context of the pharmacology of depression.展开更多
Branch identification technology is a key technology to achieve automated pruning of fruit tree branches, and one of its technical bottlenecks lies in the stitching of branch images. To this end, we propose a set of b...Branch identification technology is a key technology to achieve automated pruning of fruit tree branches, and one of its technical bottlenecks lies in the stitching of branch images. To this end, we propose a set of branch image stitching technology algorithms. The algorithm is based on the grey-scale prime centroid method to determine the detection feature points, and uses the coordinate transformation matrix H of the corresponding points of the image to carry out the image geometric transformation, and realises the feature matching through sample comparison and classification methods. The experimental results show that the matched point images are more correct and less time-consuming.展开更多
Aiming at the shortcomings of the existing automatic colony counter, a set of algorithms based on the principle of image chromatic aberration to achieve colony identification is proposed, and a colony identification d...Aiming at the shortcomings of the existing automatic colony counter, a set of algorithms based on the principle of image chromatic aberration to achieve colony identification is proposed, and a colony identification device is developed on this basis. The colony identification method is mainly based on the fact that different kinds of colonies and different concentrations of the same kind of colonies have different light-absorbing characteristics, and the judgement of colony types and concentrations is achieved through the method of image processing. The main features of the developed colony recognition equipment are high working efficiency, short recognition and detection time, and the potential of mixed recognition ability of multiple colonies. Therefore, the identification method and equipment have good application and promotion value in agriculture, food, medicine and other industries.展开更多
The automated picking technology of tea is an important part of the development of smart agriculture, which affects the development of the tea industry to a certain extent. Tea leaf recognition and robotic tea picking...The automated picking technology of tea is an important part of the development of smart agriculture, which affects the development of the tea industry to a certain extent. Tea leaf recognition and robotic tea picking end-effector are the key technologies for automated tea picking. This paper proposes a set of algorithms for tea leaf differentiation and recognition based on the principle of colour difference. And on the basis of this algorithm, a tea picking end-effector is designed. The experiments show that the designed tea picking end-effector has good recognition ability and high tea picking speed.展开更多
The dynamic stall problem for blades is related to the general performance of wind turbines,where a varying flow field is introduced with a rapid change of the effective angle of attack (AOA).The objective of this wor...The dynamic stall problem for blades is related to the general performance of wind turbines,where a varying flow field is introduced with a rapid change of the effective angle of attack (AOA).The objective of this work is to study the aerodynamic performance of a sinusoidally oscillating NACA0012 airfoil.The coupled k-ω Menter's shear stress transport (SST) turbulence model and γ-Reθ transition model were used for turbulence closure.Lagrangian coherent structures (LCS) were utilized to analyze the dynamic behavior of the flow structures.The computational results were supported by the experiments.The results indicated that this numerical method can well describe the dynamic stall process.For the case with reduced frequency K =0.1,the lift and drag coefficients increase constantly with increasing angle prior to dynamic stall.When the AOA reaches the stall angle,the lift and drag coefficients decline suddenly due to the interplay between the first leading-and trailing-edge vortex.With further increase of the AOA,both the lift and drag coefficients experience a secondary rise and fall process because of formation and shedding of the secondary vortex.The results also reveal that the dynamic behavior of the flow structures can be effectively identified using the finite-time Lyapunov exponent (FTLE) field.The influence of the reduced frequency on the flow structures and energy extraction efficiency in the dynamic stall process is further discussed.When the reduced frequency increases,the dynamic stall is delayed and the total energy extraction efficiency is enhanced.With K =0.05,the amplitude of the dynamic coefficients fluctuates more significantly in the poststall process than in the case of K =0.1.展开更多
Over-fertilization has caused significant phosphorus(P)accumulation in Chinese greenhouse vegetable production(GVP)soils.This study,for the first time,quantified profile P accumulation directly from soil P measurement...Over-fertilization has caused significant phosphorus(P)accumulation in Chinese greenhouse vegetable production(GVP)soils.This study,for the first time,quantified profile P accumulation directly from soil P measurements,as well as subsoil P immobilization,in three alkaline coarse-textured GVP soil profiles with 5(S5),15(S15),and 30(S30)years of cultivation in Tongshan,Southeast China.For each profile,soil samples were collected at depths of 0-10(topsoil),10-20,20-40,40-60,60-80,and 80-100 cm.Phosphorus accumulation was estimated from the difference in P contents between topsoil and parent material(60-100 cm subsoil).Phosphorus mobility was assessed from measurements of water-soluble P concentration(P_(Sol)).Finally,P sorption isotherms were produced using a batch sorption experiment and fitted using a modified Langmuir model.High total P contents of 1980(S5),3190(S15),and 2330(S30)mg kg^(-1) were measured in the topsoils versus lower total P content of approximately 600 mg kg^(-1) in the 80-100 cm subsoils.Likewise,topsoil PSol values were very high,varying from 6.4 to 17.0 mg L^(-1).The estimated annual P accumulations in the topsoils were 397(S5),212(S15),and 78(S30)kg ha^(-1) year^(-1).Sorption isotherms demonstrated the dominance of P desorption in highly P-saturated topsoils,whereas the amount of adsorbed P increased in the 80-100 cm subsoils with slightly larger P adsorption capacity.The total P adsorption capacity of the 80-100 cm subsoils at a solution P concentration of0.5 mg L^(-1) was 15.7(S5),8.7(S15),and 6.5(S30)kg ha^(-1),demonstrating that subsoils were unable to secure P concentrations in leaching water below 0.5 mg L^(-1) because of their insufficient P-binding capacity.展开更多
Pepsinogen,secreted from the gastric mucosa,is the precursor of pepsin.It is categorized as pepsinogen 1 and pepsinogen 2 based on its immunogenicity.The pepsinogen content that can enter the blood circulation through...Pepsinogen,secreted from the gastric mucosa,is the precursor of pepsin.It is categorized as pepsinogen 1 and pepsinogen 2 based on its immunogenicity.The pepsinogen content that can enter the blood circulation through the capillaries of the gastric mucosa is approximately 1%and remains stable all the time.The pepsinogen content in serum will change with the pathological changes of gastric mucosa.Therefore,the level of pepsinogen in serum can play a role in serologic biopsy to reflect the function and morphology of different regions of gastric mucosa and serve as an indicator of gastric disease.This study conducts relevant research on serum pepsinogen 1,pepsinogen 2,and the ratio of pepsinogen 1 to pepsinogen 2,and reviews their important value in clinical diagnosis of Helicobacter pylori infection,gastric ulcer,and even gastric carcinoma,providing ideas for other researchers.展开更多
The objective of this paper is to address the transient flow structures around a pitching hydrofoil by com- bining physical and numerical studies. In order to predict the dynamic behavior of the flow structure effecti...The objective of this paper is to address the transient flow structures around a pitching hydrofoil by com- bining physical and numerical studies. In order to predict the dynamic behavior of the flow structure effectively, the Lagrangian coherent structures （LCS） defined by the ridges of the finite-time Lyapunov exponent （FTLE） are utilized under the framework of Navier-Stokes flow computations. In the numerical simulations, the k-w shear stress trans- port （SST） turbulence model, coupled with a two-equation F-Reo transition model, is used for the turbulence closure. Results are presented for a NACA66 hydrofoil undergoing slowly and rapidly pitching motions from 0° to 15° then back to 0° at a moderate Reynolds number Re = 7.5 × 105. The results reveal that the transient flow structures can be observed by the LCS method. For the slowly pitching case, it consists of five stages： quasi-steady and laminar, transition from laminar to turbulent, vortex development, large-scale vortex shedding, and reverting to laminar. The observation of LCS and Lagrangian particle tracers elucidates that the trailing edge vortex is nearly attached and stable during the vortex development stage and the interaction between the leading and trailing edge vortex caused by the adverse pres- sure gradient forces the vortexes to shed downstream during the large-scale vortex shedding stage, which corresponds to obvious fluctuations of the hydrodynamic response. For the rapidly pitching case, the inflection is hardly to be observed and the stall is delayed. The vortex formation, interaction, and shedding occurred once instead of being repeated three times, which is responsible for just one fluctuation in the hydrody- namic characteristics. The numerical results also show that the FTLE field has the potential to identify the transient flows, and the LCS can represent the divergence extent of infinite neighboring particles and capture the interface of the vortex region.展开更多
Cavitation–structure interaction has become one of the major issues for most engineering applications. The present work reviews recent progress made toward developing experimental and numerical investigation for unst...Cavitation–structure interaction has become one of the major issues for most engineering applications. The present work reviews recent progress made toward developing experimental and numerical investigation for unsteady turbulent cavitating flow and cavitation–structure interaction. The goal of our overall efforts is to（1） summarize the progress made in the experimental and numerical modeling and approaches for unsteady cavitating flow and cavitation–structure interaction,（2） discuss the global multiphase structures for different cavitation regimes, with special emphasis on the unsteady development of cloud cavitation and corresponding cavitating flow-induced vibrations,with a high-speed visualization system and a structural vibration measurement system, as well as a simultaneous sampling system,（3） improve the understanding of the hydroelastic response in cavitating flows via combined physical and numerical analysis, with particular emphasis on the interaction between unsteady cavitation development and structural deformations. Issues including unsteady cavitating flow structures and cavitation–structure interaction mechanism are discussed.展开更多
Considering that we still do not fully understand the behavior of air pockets trapped in rainstorm systems and water flow changes inside pipes,the study of actual geysers presents many challenges.In this study,three-d...Considering that we still do not fully understand the behavior of air pockets trapped in rainstorm systems and water flow changes inside pipes,the study of actual geysers presents many challenges.In this study,three-dimensional numerical models were developed to investigate the mechanisms of geyser events triggered by rapid filling flows at different scales.The results showed that,in the first stage of the water–air mixture of the prototype model,a large amount of air was released quickly,and the subsequent overflow lasted for a more extended period.The transport capacity of the downstream pipe,as a critical factor,significantly influenced the water–air interaction of the geyser.Restricting the outlet area and increasing the outlet pressure simultaneously resulted in a stronger geyser.The equivalent density of the water–air mixture increased as the scale decreased during the geyser event.展开更多
A local vortical cavitation（LVC） model for the computation of unsteady cavitation is proposed.The model is derived from the Rayleigh–Plesset equations,and takes into account the relations between the cavitation bub...A local vortical cavitation（LVC） model for the computation of unsteady cavitation is proposed.The model is derived from the Rayleigh–Plesset equations,and takes into account the relations between the cavitation bubble radius and local vortical effects.Calculations of unsteady cloud cavitating fows around a Clark-Y hydrofoil are performed to assess the predictive capability of the LVC model using well-documented experimental data.Compared with the conventional Zwart＇s model,better agreement is observed between the predictions of the LVC model and experimental data,including measurements of time-averaged fl w structures,instantaneous cavity shapes and the frequency of the cloud cavity shedding process.Based on the predictions of the LVC model,it is demonstrated that the evaporation process largely concentrates in the core region of the leading edge vorticity in accordance with the growth in the attached cavity,and the condensation process concentrates in the core region of the trailing edge vorticity,which corresponds to the spread of the rear component of the attached cavity.When the attached cavity breaks up and moves downstream,the condensation area fully transports to the wake region,which is in accordance with the dissipation of the detached cavity.Furthermore,using vorticity transport equations,we also fin that the periodic formation,breakup,and shedding of the sheet/cloud cavities,along with the associated baroclinic torque,are important mechanisms for vorticity production and modification When the attached cavity grows,the liquid–vapour interface that moves towards the trailing edge enhances the vorticity in the attached cav-ity closure region.As the re-entrant jet moves upstream,the wavy/bubbly cavity interface enhances the vorticity near the trailing edge.At the end of the cycle,the break-up of the stable attached cavity is the main reason for the vorticity enhancement near the suction surface.展开更多
基金This research was supported by the National Natural Science Foundation of China(No.41601211)the Open Fund of the State Key Laboratory of Soil and Sustainable Agriculture,China(No.Y20160007)+1 种基金the Special Fund for Agro-scientific Research in the Public Interest,China(No.200903001-01)the Talent Fund of Qingdao Agricultural University,China(No.1114344).
文摘Monitoring the dynamics of soil salinization is of great importance for agricultural production.This study selected Yucheng County,a typical county on the Huang-Huai-Hai Plain(HHHP)of China,as the study area and evaluated the spatial and temporal variation of soil salinization.Three methods,consisting of principal component analysis(PCA)transformation,tasseled cap(TC)transformation,and optimal band combination(OBC),were used to extract information from an early Landsat multispectral scanner(MSS)image from 1984,and their advantages were compared.In addition,OBC was used on a thematic mapper(TM)image from 2009.An iteratively self-organizing data analysis algorithm was used together with prior knowledge of likely classifications to interpret the MSS and TM images for data classification.Finally,a transfer matrix method was used to assess the spatial and temporal variability of soil salinization and analyze the driving factors of soil salinization.Compared to PCA transformation and OBC,TC transformation was a more effective method for extracting soil salinization information from the MSS sensor.The results indicate that a soil area of approximately 298 km^2was affected by salinity in 1984 in Yucheng County,of which 5.40%,11.96%,and 12.75%were classified as being subject to slight,moderate,and severe salinization,respectively.In 2009,the saline area was reduced to only 146 km^2,of which 10.70%and 3.75%were characterized by slight to moderate salinization and no severe salinization,respectively.The saline land decreased at an average rate of 6 km^2per year.This decrease was probably a result of lower groundwater depth,increased organic fertilizer or crop straw in soil,changed land use type,and increased vegetation coverage.
基金funded by the Science and Technology Plan for the Belt and Road Innovation Cooperation Project of Jiangsu Province,China(No.BZ2023003)the National Key Research and Development Program of China(No.2021YFD1500202)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA28010100)the“14th Five-Year Plan”Self-Deployment Project of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSAS2418)the National Natural Science Foundation of China(No.42107334)。
文摘Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.
基金supported in part by the National Natural Science Foundation of China(62125306)Zhejiang Key Research and Development Project(2024C01163)the State Key Laboratory of Industrial Control Technology,China(ICT2024A06)
文摘In recent decades,control performance monitoring(CPM)has experienced remarkable progress in research and industrial applications.While CPM research has been investigated using various benchmarks,the historical data benchmark(HIS)has garnered the most attention due to its practicality and effectiveness.However,existing CPM reviews usually focus on the theoretical benchmark,and there is a lack of an in-depth review that thoroughly explores HIS-based methods.In this article,a comprehensive overview of HIS-based CPM is provided.First,we provide a novel static-dynamic perspective on data-level manifestations of control performance underlying typical controller capacities including regulation and servo:static and dynamic properties.The static property portrays time-independent variability in system output,and the dynamic property describes temporal behavior driven by closed-loop feedback.Accordingly,existing HIS-based CPM approaches and their intrinsic motivations are classified and analyzed from these two perspectives.Specifically,two mainstream solutions for CPM methods are summarized,including static analysis and dynamic analysis,which match data-driven techniques with actual controlling behavior.Furthermore,this paper also points out various opportunities and challenges faced in CPM for modern industry and provides promising directions in the context of artificial intelligence for inspiring future research.
基金supported by the National Key R&D Program of China(Grant No.2022YFB3303500).
文摘systematic verification and validation(V&V)of our previously proposed momentum source wave generation method is performed.Some settings of previous numerical wave tanks(NWTs)of regular and irregular waves have been optimized.The H2-5 V&V method involving five mesh sizes with mesh refinement ratio being 1.225 is used to verify the NWT of regular waves,in which the wave height and mass conservation are mainly considered based on a Lv3(H s=0.75 m)and a Lv6(H s=5 m)regular wave.Additionally,eight different sea states are chosen to validate the wave height,mass conservation and wave frequency of regular waves.Regarding the NWT of irregular waves,five different sea states with significant wave heights ranging from 0.09 m to 12.5 m are selected to validate the statistical characteristics of irregular waves,including the profile of the wave spectrum,peak frequency and significant wave height.Results show that the verification errors for Lv3 and Lv6 regular wave on the most refined grid are−0.018 and−0.35 for wave height,respectively,and−0.14 and for−0.17 mass conservation,respectively.The uncertainty estimation analysis shows that the numerical error could be partially balanced out by the modelling error to achieve a smaller validation error by adjusting the mesh size elaborately.And the validation errors of the wave height,mass conservation and dominant frequency of regular waves under different sea states are no more than 7%,8% and 2%,respectively.For a Lv3(H_(s)=0.75 m)and a Lv6(H_(s)=5 m)regular wave,simulations are validated on the wave height in wave development section for safety factors FS≈1 and FS≈0.5-1,respectively.Regarding irregular waves,the validation errors of the significant wave height and peak frequency are both lower than 2%.
基金Supported by the National Key R&D Program of China(2022YFB3303500).
文摘Numerical simulations were conducted on a 10-blade Sevik rotor ingesting wake downstream of two turbulence-generating grids.These simulations were based on implicit large-eddy simulation(ILES)and the boundary data immersion method(BDIM)for compressible flows,which were solved using a fully self-programmed Fortran code.Results show that the predicted thrust spectrum aligns closely with the experimental measurements.In addition,it captures the thrust dipole directivity of the noise around the rotating propeller due to random pressure pulsations on the blades,as well as the flow structures simultaneously.Furthermore,the differences in the statistical characteristics,flow structures,and low-frequency broadband thrust spectra due to different turbulence levels were investigated.This analysis indicates that the interaction between the upstream,which is characterized by a lower turbulence level and a higher turbulent length of scale,and the rotating propeller results in a lower amplitude in force spectra and a slight increase in the scale of tip vortices.
基金Natural Science Foundation of Zhejiang Province,No.LQ23H050005Zhejiang Medical and Health Science and Technology Project,No.2023KY615+2 种基金Scientific Research Project of Zhejiang Provincial Education Department,No.Y202250731 and No.Y202353130the China Students’Innovation and Entrepreneurship Training Program,No.202310338044China Postdoctoral Science Foundation,No.2022M721720.
文摘In this article,we revisit an article,which specifically focuses on the utilization of exosomes derived from human bone marrow mesenchymal stem cells(MSCs)for targeted delivery of gemcitabine in pancreatic cancer treatment.The experimental results demonstrated that the exosome-based drug delivery system derived from MSCs significantly augmented apoptosis in pancreatic cancer cells.The biocompatibility,targeting specificity,and low immunogenicity of exosomes render them as optimal carriers for drug delivery,enabling precise administration of therapeutics to diseased tissues while mitigating adverse effects,thereby achieving targeted treatment of cancer cells and significantly enhancing anti-tumor efficacy.However,the clinical application of exosome drug delivery platforms in oncology still presents challenges,necessitating further optimization to ensure their stability and efficacy.This study focuses on elucidating the advantages of exosomes as a drug delivery platform,exploring the utilization of MSC-derived exosomes in oncology therapy,and discussing their potential and future directions in cancer treatment.
基金financial support from the National Natural Science Foundation of China(No.52471219)the Fundamental Research Funds for the Central Universities(No.00007838)+5 种基金financial support from the National Natural Science Foundation of China(No.52471220 and U2441264)the Guangdong Basic and Applied Basic Research Foundation(No.2022A1515140051)financial support from the National Natural Science Foundation of China(No.92163209)Beijing Natural Science Foundation(No.JQ22004)financial support from the National Natural Science Foundation of China(No.52476146)Guangdong Basic and Applied Basic Research Foundation(2023A1515140059,2025A1515011255).
文摘The structural modulation of metal-based heterostructure plays a vital role in achieving enhanced performances for highly efficient electrocatalysis.Here we design submonolayered Ru-modified Pd mesoporous nanosheets(Pd-Ru MNSs)with the exposure of both Pd and Ru active sites as well as the high atomic utilization of two-dimensional structure.The obtained Pd-Ru MNSs can act as a highly efficient multifunctional catalyst for hydrogen evolution reaction(HER)and alcohol oxidation reactions including ethylene glycol oxidation(EGOR)and ethanol oxidation(EOR),offering new opportunities towards the alcohol oxidation assisted hydrogen production.Specifically,Pd-Ru MNSs demonstrate excellent HER performance in alkaline electrolyte,requiring an overpotential of only 16mV to reach 10mAcm^(−2),significantly outperforming Pd mesoporous nanosheets and commercial catalysts.Density functional theory calculations reveal that the Ru sites in Pd-Ru MNSs could facilitate the water adsorption,accelerate the water dissociation,and optimize the hydrogen desorption,leading to the superior HER activity.Pd-Ru MNSs also exhibit high mass activities of 11.19 A mg^(−1)Pd for EGOR and 8.84 A mg^(−1)Pd for EOR,which is 7.8 and 9.6 times than that of commercial Pd/C,respectively.The EGOR reaction pathway over Pd-Ru MNSs was further investigated by using in situ Fourier-transform infrared spectroscopy.
基金Supported by the National Key Research and Development Program of China,No.2019YFC1709703Jiangxi Provincial Science and Technology Department,No.20212BAG70037+1 种基金Jiangxi Provincial Education Department Science Program,No.GJJ201259Jiangxi Provincial Administration of Traditional Chinese Medicine,No.2021B324.
文摘BACKGROUND Depression significantly threatens human health.Purinergic receptors are reported to be associated with depression.However,there is no bibliometric research in this field have been published.AIM To provide some reference for the further research in the field of purinergic receptors and depression utilizing bibliometric analysis.METHODS Relevant researches were retrieved from the Web of Science Core Collection database.The period of the search was from January 1,2003 to December 31,2023.The CiteSpace(6.2.R7)and VOSviewer(1.6.19)were applied to identify the main contributors of countries,authors,institutions,references and journals.Besides,we evaluate keywords to assess the hotspots and trends over the previous 2 decades.RESULTS Totally,247 articles were identified,showing an increasing trend over time.The most productive country,institution,and journal in this field are China,Harvard University,and Biological Psychiatry,respectively.Liang SD and Rodrigues,Ana Lucia S were the most prolific authors.Burnstock G ranked first among the cited authors.The cooperation among countries and disciplines is crucial.The P2X7 receptor provides promising prospects for treating depression and further studies are warranted to validate the scope and significance of depression therapeutic strategies.CONCLUSION This study provides an overview of the worldwide research status and future trends in purinergic receptors and depression.P2X7 receptor is considered an appropriate target for the treatment of depression,as well as neurological diseases.It is implied that based on purinergic system,the future prospects for interventions aimed at depression treatment are promising,showing the way for both augmentation strategies and new drug treatments in the context of the pharmacology of depression.
文摘Branch identification technology is a key technology to achieve automated pruning of fruit tree branches, and one of its technical bottlenecks lies in the stitching of branch images. To this end, we propose a set of branch image stitching technology algorithms. The algorithm is based on the grey-scale prime centroid method to determine the detection feature points, and uses the coordinate transformation matrix H of the corresponding points of the image to carry out the image geometric transformation, and realises the feature matching through sample comparison and classification methods. The experimental results show that the matched point images are more correct and less time-consuming.
文摘Aiming at the shortcomings of the existing automatic colony counter, a set of algorithms based on the principle of image chromatic aberration to achieve colony identification is proposed, and a colony identification device is developed on this basis. The colony identification method is mainly based on the fact that different kinds of colonies and different concentrations of the same kind of colonies have different light-absorbing characteristics, and the judgement of colony types and concentrations is achieved through the method of image processing. The main features of the developed colony recognition equipment are high working efficiency, short recognition and detection time, and the potential of mixed recognition ability of multiple colonies. Therefore, the identification method and equipment have good application and promotion value in agriculture, food, medicine and other industries.
文摘The automated picking technology of tea is an important part of the development of smart agriculture, which affects the development of the tea industry to a certain extent. Tea leaf recognition and robotic tea picking end-effector are the key technologies for automated tea picking. This paper proposes a set of algorithms for tea leaf differentiation and recognition based on the principle of colour difference. And on the basis of this algorithm, a tea picking end-effector is designed. The experiments show that the designed tea picking end-effector has good recognition ability and high tea picking speed.
基金the National Postdoctoral Program for Innovative Talents(Grant BX201700126)the China Postdoctoral Science Foundation(Grant 2017M620043)+1 种基金the National Natural Science Foundation of China(Grants 51679005 and 91752105)the National Natural Science Foundation of Beijing(Grant 3172029).
文摘The dynamic stall problem for blades is related to the general performance of wind turbines,where a varying flow field is introduced with a rapid change of the effective angle of attack (AOA).The objective of this work is to study the aerodynamic performance of a sinusoidally oscillating NACA0012 airfoil.The coupled k-ω Menter's shear stress transport (SST) turbulence model and γ-Reθ transition model were used for turbulence closure.Lagrangian coherent structures (LCS) were utilized to analyze the dynamic behavior of the flow structures.The computational results were supported by the experiments.The results indicated that this numerical method can well describe the dynamic stall process.For the case with reduced frequency K =0.1,the lift and drag coefficients increase constantly with increasing angle prior to dynamic stall.When the AOA reaches the stall angle,the lift and drag coefficients decline suddenly due to the interplay between the first leading-and trailing-edge vortex.With further increase of the AOA,both the lift and drag coefficients experience a secondary rise and fall process because of formation and shedding of the secondary vortex.The results also reveal that the dynamic behavior of the flow structures can be effectively identified using the finite-time Lyapunov exponent (FTLE) field.The influence of the reduced frequency on the flow structures and energy extraction efficiency in the dynamic stall process is further discussed.When the reduced frequency increases,the dynamic stall is delayed and the total energy extraction efficiency is enhanced.With K =0.05,the amplitude of the dynamic coefficients fluctuates more significantly in the poststall process than in the case of K =0.1.
基金the financial support from the Sino-Danish Center for Education and Research(SDC)the financial support of the Special Research Foundation of the Public Natural Resource Management Department from the Ministry of Environmental Protection of China(No.201409044)the National Natural Science Foundation of China(No.41473073)。
文摘Over-fertilization has caused significant phosphorus(P)accumulation in Chinese greenhouse vegetable production(GVP)soils.This study,for the first time,quantified profile P accumulation directly from soil P measurements,as well as subsoil P immobilization,in three alkaline coarse-textured GVP soil profiles with 5(S5),15(S15),and 30(S30)years of cultivation in Tongshan,Southeast China.For each profile,soil samples were collected at depths of 0-10(topsoil),10-20,20-40,40-60,60-80,and 80-100 cm.Phosphorus accumulation was estimated from the difference in P contents between topsoil and parent material(60-100 cm subsoil).Phosphorus mobility was assessed from measurements of water-soluble P concentration(P_(Sol)).Finally,P sorption isotherms were produced using a batch sorption experiment and fitted using a modified Langmuir model.High total P contents of 1980(S5),3190(S15),and 2330(S30)mg kg^(-1) were measured in the topsoils versus lower total P content of approximately 600 mg kg^(-1) in the 80-100 cm subsoils.Likewise,topsoil PSol values were very high,varying from 6.4 to 17.0 mg L^(-1).The estimated annual P accumulations in the topsoils were 397(S5),212(S15),and 78(S30)kg ha^(-1) year^(-1).Sorption isotherms demonstrated the dominance of P desorption in highly P-saturated topsoils,whereas the amount of adsorbed P increased in the 80-100 cm subsoils with slightly larger P adsorption capacity.The total P adsorption capacity of the 80-100 cm subsoils at a solution P concentration of0.5 mg L^(-1) was 15.7(S5),8.7(S15),and 6.5(S30)kg ha^(-1),demonstrating that subsoils were unable to secure P concentrations in leaching water below 0.5 mg L^(-1) because of their insufficient P-binding capacity.
基金Supported by the National Natural Science Foundation of China,No.82172336“Pioneer”and“Leading Goose”R&D Program of Zhejiang,No.2022C03118 and No.2023C03075+1 种基金Natural Science Foundation of Zhejiang Province,No.LQ23H050005Scientific Research Project of Zhejiang Provincial Education Department,No.Y202250731.
文摘Pepsinogen,secreted from the gastric mucosa,is the precursor of pepsin.It is categorized as pepsinogen 1 and pepsinogen 2 based on its immunogenicity.The pepsinogen content that can enter the blood circulation through the capillaries of the gastric mucosa is approximately 1%and remains stable all the time.The pepsinogen content in serum will change with the pathological changes of gastric mucosa.Therefore,the level of pepsinogen in serum can play a role in serologic biopsy to reflect the function and morphology of different regions of gastric mucosa and serve as an indicator of gastric disease.This study conducts relevant research on serum pepsinogen 1,pepsinogen 2,and the ratio of pepsinogen 1 to pepsinogen 2,and reviews their important value in clinical diagnosis of Helicobacter pylori infection,gastric ulcer,and even gastric carcinoma,providing ideas for other researchers.
基金project was supported by the National Natural Science Foundation of China (Grants 51306020, 11172040)the Natural Science Foundation of Beijing (Grant 3144034)the Excellent Young Scholars Research Fund of Beijing Institute of Technology
文摘The objective of this paper is to address the transient flow structures around a pitching hydrofoil by com- bining physical and numerical studies. In order to predict the dynamic behavior of the flow structure effectively, the Lagrangian coherent structures （LCS） defined by the ridges of the finite-time Lyapunov exponent （FTLE） are utilized under the framework of Navier-Stokes flow computations. In the numerical simulations, the k-w shear stress trans- port （SST） turbulence model, coupled with a two-equation F-Reo transition model, is used for the turbulence closure. Results are presented for a NACA66 hydrofoil undergoing slowly and rapidly pitching motions from 0° to 15° then back to 0° at a moderate Reynolds number Re = 7.5 × 105. The results reveal that the transient flow structures can be observed by the LCS method. For the slowly pitching case, it consists of five stages： quasi-steady and laminar, transition from laminar to turbulent, vortex development, large-scale vortex shedding, and reverting to laminar. The observation of LCS and Lagrangian particle tracers elucidates that the trailing edge vortex is nearly attached and stable during the vortex development stage and the interaction between the leading and trailing edge vortex caused by the adverse pres- sure gradient forces the vortexes to shed downstream during the large-scale vortex shedding stage, which corresponds to obvious fluctuations of the hydrodynamic response. For the rapidly pitching case, the inflection is hardly to be observed and the stall is delayed. The vortex formation, interaction, and shedding occurred once instead of being repeated three times, which is responsible for just one fluctuation in the hydrody- namic characteristics. The numerical results also show that the FTLE field has the potential to identify the transient flows, and the LCS can represent the divergence extent of infinite neighboring particles and capture the interface of the vortex region.
基金supported by the National Natural Science Foundation of China (Grant 51679005)the Natural Science Foundation of Beijing Municipality (Grant 3172029)the Ph.D. Programs Foundation of Ministry of Education of China (Grant 20131101120014)
文摘Cavitation–structure interaction has become one of the major issues for most engineering applications. The present work reviews recent progress made toward developing experimental and numerical investigation for unsteady turbulent cavitating flow and cavitation–structure interaction. The goal of our overall efforts is to（1） summarize the progress made in the experimental and numerical modeling and approaches for unsteady cavitating flow and cavitation–structure interaction,（2） discuss the global multiphase structures for different cavitation regimes, with special emphasis on the unsteady development of cloud cavitation and corresponding cavitating flow-induced vibrations,with a high-speed visualization system and a structural vibration measurement system, as well as a simultaneous sampling system,（3） improve the understanding of the hydroelastic response in cavitating flows via combined physical and numerical analysis, with particular emphasis on the interaction between unsteady cavitation development and structural deformations. Issues including unsteady cavitating flow structures and cavitation–structure interaction mechanism are discussed.
基金supported by the National Key Laboratory of Water Disaster Prevention(Grant No.2021492011)the Natural Science Foundation of Zhejiang Province(Grant No.LQ22E090002).
文摘Considering that we still do not fully understand the behavior of air pockets trapped in rainstorm systems and water flow changes inside pipes,the study of actual geysers presents many challenges.In this study,three-dimensional numerical models were developed to investigate the mechanisms of geyser events triggered by rapid filling flows at different scales.The results showed that,in the first stage of the water–air mixture of the prototype model,a large amount of air was released quickly,and the subsequent overflow lasted for a more extended period.The transport capacity of the downstream pipe,as a critical factor,significantly influenced the water–air interaction of the geyser.Restricting the outlet area and increasing the outlet pressure simultaneously resulted in a stronger geyser.The equivalent density of the water–air mixture increased as the scale decreased during the geyser event.
基金supported by the National Natural Science Foundation of China (Grants 11172040,51239005)
文摘A local vortical cavitation（LVC） model for the computation of unsteady cavitation is proposed.The model is derived from the Rayleigh–Plesset equations,and takes into account the relations between the cavitation bubble radius and local vortical effects.Calculations of unsteady cloud cavitating fows around a Clark-Y hydrofoil are performed to assess the predictive capability of the LVC model using well-documented experimental data.Compared with the conventional Zwart＇s model,better agreement is observed between the predictions of the LVC model and experimental data,including measurements of time-averaged fl w structures,instantaneous cavity shapes and the frequency of the cloud cavity shedding process.Based on the predictions of the LVC model,it is demonstrated that the evaporation process largely concentrates in the core region of the leading edge vorticity in accordance with the growth in the attached cavity,and the condensation process concentrates in the core region of the trailing edge vorticity,which corresponds to the spread of the rear component of the attached cavity.When the attached cavity breaks up and moves downstream,the condensation area fully transports to the wake region,which is in accordance with the dissipation of the detached cavity.Furthermore,using vorticity transport equations,we also fin that the periodic formation,breakup,and shedding of the sheet/cloud cavities,along with the associated baroclinic torque,are important mechanisms for vorticity production and modification When the attached cavity grows,the liquid–vapour interface that moves towards the trailing edge enhances the vorticity in the attached cav-ity closure region.As the re-entrant jet moves upstream,the wavy/bubbly cavity interface enhances the vorticity near the trailing edge.At the end of the cycle,the break-up of the stable attached cavity is the main reason for the vorticity enhancement near the suction surface.
