Roughness-induced emission from ocean surfaces is one of the main issues that affects the retrieval accuracy of sea surface salinity remote sensing.In previous studies,the correction of roughness effect mainly depende...Roughness-induced emission from ocean surfaces is one of the main issues that affects the retrieval accuracy of sea surface salinity remote sensing.In previous studies,the correction of roughness effect mainly depended on wind speeds retrieved from scatterometers or those provided by other means,which necessitates a high requirement for accuracy and synchronicity of wind-speed measurements.The aim of this study is to develop a novel roughness correction model of ocean emissivity for the salinity retrieval application.The combined active/passive observations of normalized radar cross-sections(NRCSs)and emissivities from ocean surfaces given by the L-band Aquarius/SAC-D mission,and the auxiliary wind directions collocated from the National Centers for Environmental Prediction(NCEP)dataset are used for model development.The model is validated against the observations and the Aquarius standard algorithms of roughness-induced emissivity correction.Comparisons between model computations and measurements indicate that the model has better accuracy in computing wind-induced brightness temperature in the upwind/downwind directions or for the surfaces with smaller NRCSs,which can be better than 0.3 K.However,for crosswind directions and larger NRCSs,the model accuracy is relatively low.A model using HH-polarized NRCSs yields better accuracy than that using VV-polarized ones.For a fair comparison to the Aquarius standard algorithms using wind speeds retrieved from multi-source data,the maximum likelihood estimation is employed to produce results combining our model calculations and those using other sources.Numerical simulations show that combined results basically have higher accuracy than the standard algorithms.展开更多
Surge active control can expand the stable operating range of the compressor.However,the difficulty of flow measurement,dynamic uncertainty disturbance,actuator delay characteristics,hard constraints of control variab...Surge active control can expand the stable operating range of the compressor.However,the difficulty of flow measurement,dynamic uncertainty disturbance,actuator delay characteristics,hard constraints of control variable,and system security measures have not been fully considered in the existing active control system,which significantly hinders its engineering application.Therefore,a nonlinear model predictive surge active control method is first presented based on flow estimator designed by using a continuous-time Kalman filter for dealing with the hard constraint of control variable and the impact of actuator delay of compression system with dynamic uncertainty.Then,a high-safety active/surge passive hybrid control strategy is designed,dominated by the surge active control and supplemented by the surge passive control,to ensure the compression system’s safe and stable operation.Lastly,the simulation results suggest that the flow estimator accurately estimates the compressor flow.When considering the delay impact of the actuators and sensors and measurement noise on the system,the proposed method exhibits stronger robustness than the existing meth-ods.The active/surge passive hybrid control strategy can successfully ensure the compression system’s safe and stable operation.This paper is of high practical significance for the engineering application of future compressor surge active control technologies.展开更多
This article provides a comprehensive review of various approaches to targeted drug delivery for liver cancer, an area of significant need due to the limited effectiveness of current treatments. The article begins by ...This article provides a comprehensive review of various approaches to targeted drug delivery for liver cancer, an area of significant need due to the limited effectiveness of current treatments. The article begins by highlighting the role of the liver in metabolism and discusses the high mortality associated with hepatocellular carcinoma (HCC). The shortcomings of traditional chemotherapy, such as multidrug resistance and off-target effects, necessitate the exploration of novel therapeutic strategies, with a focus on targeted approaches. The review details both passive and active targeting strategies. Passive targeting leverages the enhanced permeability and retention (EPR) effect and unique features of the tumor microenvironment, while active targeting employs specific ligands, such as peptides, antibodies, and proteins, to bind to overexpressed receptors on liver and tumor cells. The article further details many examples of active targeting using the asialoglycoprotein receptor (ASGPR), glycyrrhetinic acid (GA), transferrin receptor (TfR), and folate receptor (FR) on hepatocytes and tumor cells, demonstrating that there has been significant research effort put into this field. The importance of non-parenchymal cells in the liver is also discussed, and the article examines methods of targeting Kupffer cells, sinusoidal endothelial cells, and hepatic stellate cells for therapeutic benefit. The review goes on to cover the emerging field of subcellular targeting, including specific strategies to target the nucleus, mitochondria, and the endoplasmic reticulum/Golgi apparatus, noting that although there has been some progress, further research is needed in this area. The text finishes with a summary which acknowledges that while targeted therapies, including enzyme-activated prodrugs, such as Pradefovir, and other novel methods for drug delivery have shown significant promise, challenges remain in translating these therapies into clinical use due to limitations in understanding the sequential transport and the mechanisms of action. Ultimately, the article emphasizes the need for in-depth research to fully realize the potential of precision cancer therapies for liver cancer.展开更多
Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these...Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.展开更多
Corrosion activities and related accidents are significant issues for marine facilities,leading to considerable economic losses.Waterborne epoxy(EP)coating has been seen as one of the optimal options for corrosion pro...Corrosion activities and related accidents are significant issues for marine facilities,leading to considerable economic losses.Waterborne epoxy(EP)coating has been seen as one of the optimal options for corrosion protection due to its stable properties and eco-friendliness(0 g/L volatile organic compounds).Nevertheless,several intrinsic deficiencies require improvement,such as fragile mechanical properties and defects(macro and micro),resulting in the continuous deterioration of comprehensive coating performances.In this work,a novel nanocomposite coating with mechanical enhancement,intelligent self-reporting,and active protection is fabricated by integrating the functionalized and compatible graphene oxide/cerium based metal-organic framework multiscale structure(GO-CeMOF-P/M).Notably,the homogenous dispersion of GO-CeMOF-P/M and its chemical interaction with the polymer matrix effectively reduces the defects resulting from solution volatilizing and enhances the compactness,which boosts the tensile strength(32.1 MPa/8.5%)and dry adhesion force(5.8 MPa)of the coating.Additionally,the controllable responsiveness and release of multiscale nanocomposite within external environments endow intelligent active protection and self-reporting characteristics for the GO-CeMOF-P/M-EP coating,making it especially suitable for a variety of practical marine applications.Furthermore,following immersion of 80 d in the aggressive environment,Zf=0.01 Hz value of GO-CeMOF-P/M-EP coating is 1.2×10^(10)Ωcm^(2),which is 164.4 times larger than that of EP coating(7.3×10^(7)Ωcm^(2)),demonstrating remarkably strengthened anti-corrosion ability.Consequently,by offering an intriguing design strategy,the current work anticipates addressing the inherent deficiencies of EP coating and facilitating its practicality and feasibility in real sea environments.展开更多
Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink...Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions.展开更多
Passive seismic data contain large amounts of low-frequency information. To effectively extract and compensate active seismic data that lack low frequencies, we propose a multitaper spectral reconstruction method base...Passive seismic data contain large amounts of low-frequency information. To effectively extract and compensate active seismic data that lack low frequencies, we propose a multitaper spectral reconstruction method based on multiple sinusoidal tapers and derive equations for multisource and multitrace conditions. Compared to conventional cross correlation and deconvolution reconstruction methods, the proposed method can more accurately reconstruct the relative amplitude of recordings. Multidomain iterative denoising improves the SNR of retrieved data. By analyzing the spectral characteristics of passive data before and after reconstruction, we found that the data are expressed more clearly after reconstruction and denoising. To compensate for the low-frequency information in active data using passive seismic data, we match the power spectrum, supplement it, and then smooth it in the frequency domain. Finally, we use numerical simulation to verify the proposed method and conduct prestack depth migration using data after low-frequency compensation. The proposed power-matching method adds the losing low frequency information in the active seismic data using the low-frequency information of passive- source seismic data. The imaging of compensated data gives a more detailed information of deep structures.展开更多
Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors c...Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors consume less power,but lack the capability to resolve static stimuli.Here,we address this issue by utilizing the unique polarization chemistry of conjugated polymers for the first time and propose a new type of bioinspired,passive,and bio-friendly tactile sensors for resolving both static and dynamic stimuli.Specifically,to emulate the polarization process of natural sensory cells,conjugated polymers(including poly(3,4-ethylenedioxythiophen e):poly(styrenesulfonate),polyaniline,or polypyrrole)are controllably polarized into two opposite states to create artificial potential differences.The controllable and reversible polarization process of the conjugated polymers is fully in situ characterized.Then,a micro-structured ionic electrolyte is employed to imitate the natural ion channels and to encode external touch stimulations into the variation in potential difference outputs.Compared with the currently existing tactile sensing devices,the developed tactile sensors feature distinct characteristics including fully organic composition,high sensitivity(up to 773 mV N^(−1)),ultralow power consumption(nW),as well as superior bio-friendliness.As demonstrations,both single point tactile perception(surface texture perception and material property perception)and two-dimensional tactile recognitions(shape or profile perception)with high accuracy are successfully realized using self-defined machine learning algorithms.This tactile sensing concept innovation based on the polarization chemistry of conjugated polymers opens up a new path to create robotic tactile sensors and prosthetic electronic skins.展开更多
In clinical practice,antibiotics have historically been utilized for the treatment of pathogenic bacteria.However,the gradual emergence of antibiotic resistance among bacterial strains has posed a significant challeng...In clinical practice,antibiotics have historically been utilized for the treatment of pathogenic bacteria.However,the gradual emergence of antibiotic resistance among bacterial strains has posed a significant challenge to this approach.In 2022,Escherichia coli,a Gram-negative bacterium renowned for its widespread pathogenicity and high virulence,emerged as the predominant pathogenic bacterium in China.The rapid emergence of antibiotic-resistant E.coli strains has rendered antibiotics insufficient to fight E.coli infections.Traditional Chinese medicine(TCM)has made remarkable contributions to the health of Chinese people for thousands of years,and its significant therapeutic effects have been proven in clinical practice.In this paper,we provide a comprehensive review of the advances and mechanisms of TCM and its active ingredients against antibiotic-resistant E.coli infections.First of all,this review introduces the classification,antibiotic resistance characteristics and mechanisms of E.coli.Then,the TCM formulas and extracts are listed along with their active ingredients against E.coli,including extraction solution,minimum inhibitory concentration(MIC),and the antibacterial mechanisms.In addition,there is growing evidence supporting the synergistic therapeutic strategy of combining TCM with antibiotics for the treatment of antibiotic-resistant E.coli infections,and we provide a summary of this evidence and its underlying mechanisms.In conclusion,we present a comprehensive review of TCM and highlight its potential and advantages in the prevention and treatment of E.coli infections.We hold the opinion that TCM will play an important role in global health,pharmaceutical development,and livestock farming in the future.展开更多
Gallium nitride(GaN)single crystal with prominent electron mobility and heat resistance have great potential in the high temperature integrate electric power systems.However,the sluggish charge storage kinetics and in...Gallium nitride(GaN)single crystal with prominent electron mobility and heat resistance have great potential in the high temperature integrate electric power systems.However,the sluggish charge storage kinetics and inadequate energy densities are bottlenecks to its practical application.Herein,the self-supported GaN/Mn_(3)O_(4) integrated electrode is developed for both energy harvesting and storage under the high temperature environment.The experimental and theoretical calculations results reveal that such integrated structures with Mn-N heterointerface bring abundant active sites and reconstruct low-energy barrier channels for efficient charge transferring,reasonably optimizing the ions adsorption ability and strengthening the structural stability.Consequently,the assembled GaN based supercapacitors deliver the power density of 34.0 mW cm^(-2) with capacitance retention of 81.3%after 10000 cycles at 130℃.This work innovatively correlates the centimeter scale GaN single crystal with ideal theoretical capacity Mn_(3)O_(4) and provides an effective avenue for the follow-up energy storage applications of the wide bandgap semiconductor.展开更多
We conduct optical-tweezers experiments to investigate the average potential energies of passive plates harmonically trapped in bacterial suspensions.Our results show that the mean potential energies along both the ma...We conduct optical-tweezers experiments to investigate the average potential energies of passive plates harmonically trapped in bacterial suspensions.Our results show that the mean potential energies along both the major and minor axes increase with bacterial concentration but decrease with trap stiffness.Notably,the average potential energy along the major axis consistently exceeds that along the minor axis.This discrepancy from equilibrium systems is primarily attributed to the distinct bacterial flow fields and direct bacterium–plate collisions near the major and minor axes,as evidenced by the higher orientational order around the plate along the major compared to the minor axis,despite identical bacterial densities in these regions.Our findings highlight the critical role of hydrodynamic interactions in determining the potential energy of passive objects immersed in an active bath.展开更多
Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical...Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology.展开更多
Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it m...Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal aging.This work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging extent.For comparison,the H-BEA support was aged under the same conditions.Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3)temperature programmed reduction(NH_(3)-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and acidity.The HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce species.Based on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.展开更多
Considering the uncertainty of grid connection of electric vehicle charging stations and the uncertainty of new energy and residential electricity load,a spatio-temporal decoupling strategy of dynamic reactive power o...Considering the uncertainty of grid connection of electric vehicle charging stations and the uncertainty of new energy and residential electricity load,a spatio-temporal decoupling strategy of dynamic reactive power optimization based on clustering-local relaxation-correction is proposed.Firstly,the k-medoids clustering algorithm is used to divide the reduced power scene into periods.Then,the discrete variables and continuous variables are optimized in the same period of time.Finally,the number of input groups of parallel capacitor banks(CB)in multiple periods is fixed,and then the secondary static reactive power optimization correction is carried out by using the continuous reactive power output device based on the static reactive power compensation device(SVC),the new energy grid-connected inverter,and the electric vehicle charging station.According to the characteristics of the model,a hybrid optimization algorithm with a cross-feedback mechanism is used to solve different types of variables,and an improved artificial hummingbird algorithm based on tent chaotic mapping and adaptive mutation is proposed to improve the solution efficiency.The simulation results show that the proposed decoupling strategy can obtain satisfactory optimization resultswhile strictly guaranteeing the dynamic constraints of discrete variables,and the hybrid algorithm can effectively solve the mixed integer nonlinear optimization problem.展开更多
Cu/ZnO-based catalysts are widely employed for methanol synthesis via CO_(2) hydrogenation.The preparation procedure is sensitive to the particle size and interfacial structure,which are considered as potential active...Cu/ZnO-based catalysts are widely employed for methanol synthesis via CO_(2) hydrogenation.The preparation procedure is sensitive to the particle size and interfacial structure,which are considered as potential active centers influencing the rate of both methanol and CO formation.The particle size and the interaction between Cu and the support materials are influenced by the coprecipitation conditions,let alone that the mechanistic divergence remains unclear.In this work,a series of Cu/ZnO/ZrO_(2) catalysts were prepared via co-precipitation at different pH value and systematically characterized.The structure has been correlated with kinetic results to establish the structure-performance relationship.Kinetic analysis demonstrates that methanol synthesis follows a single-site Langmuir-Hinshelwood(L-H)mechanism,i.e.,Cu serves as the active site where CO_(2) and H_(2) competitively adsorb and react to form methanol.In contrast,CO formation proceeds via a dual-site L-H mechanism,where CO_(2) adsorbs onto ZnO and H_(2) onto Cu,with the reaction occurring at the Cu/ZnO interface.Therefore,for the direct formation of methanol,solely reducing the particle size of Cu would not be beneficial.展开更多
A novel method is developed by utilizing the fractional frequency based multirange rulers to precisely position the passive inter-modulation(PIM)sources within radio frequency(RF)cables.The proposed method employs a s...A novel method is developed by utilizing the fractional frequency based multirange rulers to precisely position the passive inter-modulation(PIM)sources within radio frequency(RF)cables.The proposed method employs a set of fractional frequencies to create multiple measuring rulers with different metric ranges to determine the values of the tens,ones,tenths,and hundredths digits of the distance.Among these rulers,the one with the lowest frequency determines the maximum metric range,while the one with the highest frequency decides the highest achievable accuracy of the position system.For all rulers,the metric accuracy is uniquely determined by the phase accuracy of the detected PIM signals.With the all-phase Fourier transform method,the phases of the PIM signals at all fractional frequencies maintain almost the same accuracy,approximately 1°(about 1/360 wavelength in the positioning accuracy)at the signal-to-noise ratio(SNR)of 10 d B.Numerical simulations verify the effectiveness of the proposed method,improving the positioning accuracy of the cable PIM up to a millimeter level with the highest fractional frequency operating at 200 MHz.展开更多
This paper investigates how to achieve integrated sensing and communication(ISAC)based on a cell-free radio access network(CF-RAN)architecture with a minimum footprint of communication resources.We propose a new passi...This paper investigates how to achieve integrated sensing and communication(ISAC)based on a cell-free radio access network(CF-RAN)architecture with a minimum footprint of communication resources.We propose a new passive sensing scheme.The scheme is based on the radio frequency(RF)fingerprint learning of the RF radio unit(RRU)to build an RF fingerprint library of RRUs.The source RRU is identified by comparing the RF fingerprints carried by the signal at the receiver side.The receiver extracts the channel parameters from the signal and estimates the channel environment,thus locating the reflectors in the environment.The proposed scheme can effectively solve the problem of interference between signals in the same time-frequency domain but in different spatial domains when multiple RRUs jointly serve users in CF-RAN architecture.Simulation results show that the proposed passive ISAC scheme can effectively detect reflector location information in the environment without degrading the communication performance.展开更多
In the last decade,the study of pressure in active matter has attracted growing attention due to its fundamental relevance to nonequilibrium statistical physics.Active matter systems are composed of particles that con...In the last decade,the study of pressure in active matter has attracted growing attention due to its fundamental relevance to nonequilibrium statistical physics.Active matter systems are composed of particles that consume energy to sustain persistent motion,which are inherently far from equilibrium.These particles can exhibit complex behaviors,including motility-induced phase separation,clustering,and anomalous stress distributions,motivating the introduction of active swim stress and swim pressure.Unlike in passive fluids,pressure in active systems emerges from momentum flux originating from swim force rather than equilibrium conservative interactions,offering a distinct perspective for understanding their mechanical response.Simple models of active Brownian particles(ABPs)have been employed in theoretical and simulation studies across both dilute and dense regimes,revealing that pressure is a state function and exhibits a nontrivial dependence on density.Together with nonequilibrium statistical concepts such as effective temperature and effective adhesion,pressure offers important insight for understanding behaviors in active matter such as sedimentation equilibrium and motility induced phase separation.Extensions of ABP models beyond their simplest form have underscored the fragility of the pressure-based equation of state,which can break down under factors such as density-dependent velocity,torque,complex boundary geometries and interactions.Building on these developments,this review provides a comprehensive survey of theoretical and experimental advances,with particular emphasis on the microscopic origins of active pressure and the mechanisms underlying the breakdown of the equation of state.展开更多
Polygonati Rhizoma,a functional food and a traditional Chinese medicine broadly used in China and several Southeast Asia countries,possesses effective health-promoting activities.Prepared from 3 plants in Polygonatum ...Polygonati Rhizoma,a functional food and a traditional Chinese medicine broadly used in China and several Southeast Asia countries,possesses effective health-promoting activities.Prepared from 3 plants in Polygonatum genus(Polygonatum kingianum,Polygonatum sibiricum,and Polygonatum cyrtonema),Polygonati Rhizoma has drawn increasing attention due to its remarkable immune-enhancing and metabolic regulatory activities in recent years.In this review,we summarized the updated research of chemical constituents and biological activities of Polygonati Rhizoma,especially the metabolic regulation,immunomodulatory effects,and anti-fatigue activities,aiming to provide a comprehensive understanding,broaden the usage and promote more in-depth exploration of Polygonati Rhizoma as a functional food.展开更多
基金The National Key R&D Program of China under contract Nos 2018YFA0605403 and 2016YFB0500204the Hainan Provincial Natural Science Foundation of China under contract No.418QN301the National Natural Science Foundation of China under contract No.41801238。
文摘Roughness-induced emission from ocean surfaces is one of the main issues that affects the retrieval accuracy of sea surface salinity remote sensing.In previous studies,the correction of roughness effect mainly depended on wind speeds retrieved from scatterometers or those provided by other means,which necessitates a high requirement for accuracy and synchronicity of wind-speed measurements.The aim of this study is to develop a novel roughness correction model of ocean emissivity for the salinity retrieval application.The combined active/passive observations of normalized radar cross-sections(NRCSs)and emissivities from ocean surfaces given by the L-band Aquarius/SAC-D mission,and the auxiliary wind directions collocated from the National Centers for Environmental Prediction(NCEP)dataset are used for model development.The model is validated against the observations and the Aquarius standard algorithms of roughness-induced emissivity correction.Comparisons between model computations and measurements indicate that the model has better accuracy in computing wind-induced brightness temperature in the upwind/downwind directions or for the surfaces with smaller NRCSs,which can be better than 0.3 K.However,for crosswind directions and larger NRCSs,the model accuracy is relatively low.A model using HH-polarized NRCSs yields better accuracy than that using VV-polarized ones.For a fair comparison to the Aquarius standard algorithms using wind speeds retrieved from multi-source data,the maximum likelihood estimation is employed to produce results combining our model calculations and those using other sources.Numerical simulations show that combined results basically have higher accuracy than the standard algorithms.
基金supported by the National Natural Science Foundation of China(Nos.51906103,52176009).
文摘Surge active control can expand the stable operating range of the compressor.However,the difficulty of flow measurement,dynamic uncertainty disturbance,actuator delay characteristics,hard constraints of control variable,and system security measures have not been fully considered in the existing active control system,which significantly hinders its engineering application.Therefore,a nonlinear model predictive surge active control method is first presented based on flow estimator designed by using a continuous-time Kalman filter for dealing with the hard constraint of control variable and the impact of actuator delay of compression system with dynamic uncertainty.Then,a high-safety active/surge passive hybrid control strategy is designed,dominated by the surge active control and supplemented by the surge passive control,to ensure the compression system’s safe and stable operation.Lastly,the simulation results suggest that the flow estimator accurately estimates the compressor flow.When considering the delay impact of the actuators and sensors and measurement noise on the system,the proposed method exhibits stronger robustness than the existing meth-ods.The active/surge passive hybrid control strategy can successfully ensure the compression system’s safe and stable operation.This paper is of high practical significance for the engineering application of future compressor surge active control technologies.
文摘This article provides a comprehensive review of various approaches to targeted drug delivery for liver cancer, an area of significant need due to the limited effectiveness of current treatments. The article begins by highlighting the role of the liver in metabolism and discusses the high mortality associated with hepatocellular carcinoma (HCC). The shortcomings of traditional chemotherapy, such as multidrug resistance and off-target effects, necessitate the exploration of novel therapeutic strategies, with a focus on targeted approaches. The review details both passive and active targeting strategies. Passive targeting leverages the enhanced permeability and retention (EPR) effect and unique features of the tumor microenvironment, while active targeting employs specific ligands, such as peptides, antibodies, and proteins, to bind to overexpressed receptors on liver and tumor cells. The article further details many examples of active targeting using the asialoglycoprotein receptor (ASGPR), glycyrrhetinic acid (GA), transferrin receptor (TfR), and folate receptor (FR) on hepatocytes and tumor cells, demonstrating that there has been significant research effort put into this field. The importance of non-parenchymal cells in the liver is also discussed, and the article examines methods of targeting Kupffer cells, sinusoidal endothelial cells, and hepatic stellate cells for therapeutic benefit. The review goes on to cover the emerging field of subcellular targeting, including specific strategies to target the nucleus, mitochondria, and the endoplasmic reticulum/Golgi apparatus, noting that although there has been some progress, further research is needed in this area. The text finishes with a summary which acknowledges that while targeted therapies, including enzyme-activated prodrugs, such as Pradefovir, and other novel methods for drug delivery have shown significant promise, challenges remain in translating these therapies into clinical use due to limitations in understanding the sequential transport and the mechanisms of action. Ultimately, the article emphasizes the need for in-depth research to fully realize the potential of precision cancer therapies for liver cancer.
基金supported by the Fundamental Research Funds for Central Public Welfare Research Institute,No.2020CZ-5(to WS and GS)the National Natural Science Foundation of China,No.31970970(to JSR)Fundamental Research Funds for the Central Universities,No.YWF-23-YG-QB-010(to JSR)。
文摘Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury level.However,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface electromyography.In this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord injury.Eleven patients with chronic complete thoracic spinal cord injury were recruited.Surface electromyography data from eight major leg muscles were acquired and compared before and after the passive activity protocol.The results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of activation.Although the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically significant.These findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.
基金financially supported by the National Natural Science Foundation of China(Nos.52371088,52071347,and U20A20233)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515240007)Shenzhen Science and Technology Program(No.KJZD20230923114819041).
文摘Corrosion activities and related accidents are significant issues for marine facilities,leading to considerable economic losses.Waterborne epoxy(EP)coating has been seen as one of the optimal options for corrosion protection due to its stable properties and eco-friendliness(0 g/L volatile organic compounds).Nevertheless,several intrinsic deficiencies require improvement,such as fragile mechanical properties and defects(macro and micro),resulting in the continuous deterioration of comprehensive coating performances.In this work,a novel nanocomposite coating with mechanical enhancement,intelligent self-reporting,and active protection is fabricated by integrating the functionalized and compatible graphene oxide/cerium based metal-organic framework multiscale structure(GO-CeMOF-P/M).Notably,the homogenous dispersion of GO-CeMOF-P/M and its chemical interaction with the polymer matrix effectively reduces the defects resulting from solution volatilizing and enhances the compactness,which boosts the tensile strength(32.1 MPa/8.5%)and dry adhesion force(5.8 MPa)of the coating.Additionally,the controllable responsiveness and release of multiscale nanocomposite within external environments endow intelligent active protection and self-reporting characteristics for the GO-CeMOF-P/M-EP coating,making it especially suitable for a variety of practical marine applications.Furthermore,following immersion of 80 d in the aggressive environment,Zf=0.01 Hz value of GO-CeMOF-P/M-EP coating is 1.2×10^(10)Ωcm^(2),which is 164.4 times larger than that of EP coating(7.3×10^(7)Ωcm^(2)),demonstrating remarkably strengthened anti-corrosion ability.Consequently,by offering an intriguing design strategy,the current work anticipates addressing the inherent deficiencies of EP coating and facilitating its practicality and feasibility in real sea environments.
文摘Integrated sensing and communication(ISAC) is considered an effective technique to solve spectrum congestion in the future. In this paper, we consider a hybrid reconfigurable intelligent surface(RIS)-assisted downlink ISAC system that simultaneously serves multiple single-antenna communication users and senses multiple targets. Hybrid RIS differs from fully passive RIS in that it is composed of both active and passive elements, with the active elements having the effect of amplifying the signal in addition to phase-shifting. We maximize the achievable sum rate of communication users by collaboratively improving the beamforming matrix at the dual function base station(DFBS) and the phase-shifting matrix of the hybrid RIS, subject to the transmit power constraint at the DFBS, the signal-to-interference-plus-noise-ratio(SINR) constraint of the radar echo signal and the RIS constraint are satisfied at the same time. The builtin RIS-assisted ISAC design problem model is significantly non-convex due to the fractional objective function of this optimization problem and the coupling of the optimization variables in the objective function and constraints. As a result, we provide an effective alternating optimization approach based on fractional programming(FP) with block coordinate descent(BCD)to solve the optimization variables. Results from simulations show that the hybrid RIS-assisted ISAC system outperforms the other benchmark solutions.
基金sponsored by the Natural Science Foundation of China(No.41374115)National High Technology Research and Development Program of China(863 project)(No.2014AA06A605)
文摘Passive seismic data contain large amounts of low-frequency information. To effectively extract and compensate active seismic data that lack low frequencies, we propose a multitaper spectral reconstruction method based on multiple sinusoidal tapers and derive equations for multisource and multitrace conditions. Compared to conventional cross correlation and deconvolution reconstruction methods, the proposed method can more accurately reconstruct the relative amplitude of recordings. Multidomain iterative denoising improves the SNR of retrieved data. By analyzing the spectral characteristics of passive data before and after reconstruction, we found that the data are expressed more clearly after reconstruction and denoising. To compensate for the low-frequency information in active data using passive seismic data, we match the power spectrum, supplement it, and then smooth it in the frequency domain. Finally, we use numerical simulation to verify the proposed method and conduct prestack depth migration using data after low-frequency compensation. The proposed power-matching method adds the losing low frequency information in the active seismic data using the low-frequency information of passive- source seismic data. The imaging of compensated data gives a more detailed information of deep structures.
基金financially supported by the Sichuan Science and Technology Program(2022YFS0025 and 2024YFFK0133)supported by the“Fundamental Research Funds for the Central Universities of China.”。
文摘Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots.Compared to active sensing devices,passive piezoelectric and triboelectric tactile sensors consume less power,but lack the capability to resolve static stimuli.Here,we address this issue by utilizing the unique polarization chemistry of conjugated polymers for the first time and propose a new type of bioinspired,passive,and bio-friendly tactile sensors for resolving both static and dynamic stimuli.Specifically,to emulate the polarization process of natural sensory cells,conjugated polymers(including poly(3,4-ethylenedioxythiophen e):poly(styrenesulfonate),polyaniline,or polypyrrole)are controllably polarized into two opposite states to create artificial potential differences.The controllable and reversible polarization process of the conjugated polymers is fully in situ characterized.Then,a micro-structured ionic electrolyte is employed to imitate the natural ion channels and to encode external touch stimulations into the variation in potential difference outputs.Compared with the currently existing tactile sensing devices,the developed tactile sensors feature distinct characteristics including fully organic composition,high sensitivity(up to 773 mV N^(−1)),ultralow power consumption(nW),as well as superior bio-friendliness.As demonstrations,both single point tactile perception(surface texture perception and material property perception)and two-dimensional tactile recognitions(shape or profile perception)with high accuracy are successfully realized using self-defined machine learning algorithms.This tactile sensing concept innovation based on the polarization chemistry of conjugated polymers opens up a new path to create robotic tactile sensors and prosthetic electronic skins.
基金supported by the Fundamental Research Funds for the Central Public Welfare Research Institutes,China(Grant Nos.:ZZ16-YQ-037,JIPY2023003,and JJPY2022022)China Academy of Chinese Medical Sciences(CACMS)Innovation Fund(Grant No.:CI2021A00601).
文摘In clinical practice,antibiotics have historically been utilized for the treatment of pathogenic bacteria.However,the gradual emergence of antibiotic resistance among bacterial strains has posed a significant challenge to this approach.In 2022,Escherichia coli,a Gram-negative bacterium renowned for its widespread pathogenicity and high virulence,emerged as the predominant pathogenic bacterium in China.The rapid emergence of antibiotic-resistant E.coli strains has rendered antibiotics insufficient to fight E.coli infections.Traditional Chinese medicine(TCM)has made remarkable contributions to the health of Chinese people for thousands of years,and its significant therapeutic effects have been proven in clinical practice.In this paper,we provide a comprehensive review of the advances and mechanisms of TCM and its active ingredients against antibiotic-resistant E.coli infections.First of all,this review introduces the classification,antibiotic resistance characteristics and mechanisms of E.coli.Then,the TCM formulas and extracts are listed along with their active ingredients against E.coli,including extraction solution,minimum inhibitory concentration(MIC),and the antibacterial mechanisms.In addition,there is growing evidence supporting the synergistic therapeutic strategy of combining TCM with antibiotics for the treatment of antibiotic-resistant E.coli infections,and we provide a summary of this evidence and its underlying mechanisms.In conclusion,we present a comprehensive review of TCM and highlight its potential and advantages in the prevention and treatment of E.coli infections.We hold the opinion that TCM will play an important role in global health,pharmaceutical development,and livestock farming in the future.
基金supported by NSFC(Grant No.52202265,52302004,52472010,62434010)the Taishan Scholars Program of Shandong Province(tsqn202306330)+1 种基金Shenzhen Science and Technology Program(JCYJ20230807094009018)Xiaomi Young Talents Program(2023XM06).
文摘Gallium nitride(GaN)single crystal with prominent electron mobility and heat resistance have great potential in the high temperature integrate electric power systems.However,the sluggish charge storage kinetics and inadequate energy densities are bottlenecks to its practical application.Herein,the self-supported GaN/Mn_(3)O_(4) integrated electrode is developed for both energy harvesting and storage under the high temperature environment.The experimental and theoretical calculations results reveal that such integrated structures with Mn-N heterointerface bring abundant active sites and reconstruct low-energy barrier channels for efficient charge transferring,reasonably optimizing the ions adsorption ability and strengthening the structural stability.Consequently,the assembled GaN based supercapacitors deliver the power density of 34.0 mW cm^(-2) with capacitance retention of 81.3%after 10000 cycles at 130℃.This work innovatively correlates the centimeter scale GaN single crystal with ideal theoretical capacity Mn_(3)O_(4) and provides an effective avenue for the follow-up energy storage applications of the wide bandgap semiconductor.
基金supports of the National Natural Science Foundation of China(Grant Nos.12304245,12374205,12475031,and 12364029)the Science Foundation of China University of Petroleum,Beijing(Grant Nos.2462023YJRC031 and 2462024BJRC010)+4 种基金the National Key Laboratory of Petroleum Resources and Engineering(Grant No.PRE/DX-2407)the Natural Science Foundation of Shandong Province(Grant No.ZR2024YQ017)the Young Elite Scientist Sponsorship Program by BAST(Grant No.BYESS2023300)the Beijing Institute of Technology Research Fund Program for Young ScholarsThis work was also supported by Beijing National Laboratory for Condensed Matter Physics(Grant Nos.2023BNLCMPKF014 and 2024BNLCMPKF009).
文摘We conduct optical-tweezers experiments to investigate the average potential energies of passive plates harmonically trapped in bacterial suspensions.Our results show that the mean potential energies along both the major and minor axes increase with bacterial concentration but decrease with trap stiffness.Notably,the average potential energy along the major axis consistently exceeds that along the minor axis.This discrepancy from equilibrium systems is primarily attributed to the distinct bacterial flow fields and direct bacterium–plate collisions near the major and minor axes,as evidenced by the higher orientational order around the plate along the major compared to the minor axis,despite identical bacterial densities in these regions.Our findings highlight the critical role of hydrodynamic interactions in determining the potential energy of passive objects immersed in an active bath.
基金supported by the National Natural Science Foundation of China(Nos.52177059 and 52407064).
文摘Permanent magnet synchronous motor based electro-mechanical actuation servo drives have widespread applications in the aviation field,such as unmanned aerial vehicle electric servos,electric cabin doors,and mechanical arms.The performance of the servo drive,which encompasses the response to the torque,efficiency,control bandwidth and the steady-state positioning accuracy,significantly influences the performance of the aviation actuation.Consequently,enhancing the control bandwidth and refining the positioning accuracy of aviation electro-mechanical actuation servo drives have emerged as a focal point of research.This paper investigates the multi-source disturbances present in aviation electro-mechanical actuation servo systems and summarizes recent research on high-performance servo control methods based on active disturbance rejection control(ADRC).We present a comprehensive overview of the research status pertaining to servo control architecture,strategies for suppressing disturbances in the current loop,and ADRC-based strategies for the position loop.We delineate the research challenges and difficulties encountered by aviation electro-mechanical actuation servo drive control technology.
基金supported the National Key R&D Program of China(2021YFB3503200)the Innovative Research Groups of the National Natural Science Foundation of China(51921004)+1 种基金Young Elite Scientists Sponsorship Program by CAST(2021QNRC001)the Key R&D Project of Shandong Province(2021CXGC010703,2022CXGC020311)。
文摘Ce/BEA has the potential to be applied as a novel passive NO_(x)absorber(PNA)in the after-treatment of vehicles due to its considerable NO_(x)storage capacity.However,as a vehicle exhaust after-treatment material,it must withstand the test of long-term hydrothermal aging.This work examined the deactivation mechanism of Ce/BEA during hydrothermal aging.3.0 wt%Ce/BEA was prepared using the ionexchange method,and then subjected to hydrothermal treatment at 650℃with 10%H_(2)O for 1-12 h to obtain samples with different aging extent.For comparison,the H-BEA support was aged under the same conditions.Brunauer-Emmett-Teller(BET)method,X-ray diffraction(XRD),NH_(3)temperature programmed reduction(NH_(3)-TPD),^(27)Al MAS nuclear magnetic resonance(^(27)Al MAS NMR),H_(2)temperature programmed reduction(H_(2)-TPR),and high resolution-transmission electron microscopy(HR-TEM)were performed to characterize the changes in PNA performance,structure,Ce species,and acidity.The HR-TEM and H_(2)-TPR results show that CeO_(x)particles appear after hydrothermal aging,which results from the detachment and aggregation of active Ce species.Based on the^(27)Al MAS NMR results,we conclude that BEA zeolite dealumination leads to the loss of acidic sites and the transformation of active Ce species on the acidic sites into the less active CeO_(x).This is the primary reason for the hydrothermal aging deactivation of Ce/BEA.
基金funded by the“Research and Application Project of Collaborative Optimization Control Technology for Distribution Station Area for High Proportion Distributed PV Consumption(4000-202318079A-1-1-ZN)”of the Headquarters of the State Grid Corporation.
文摘Considering the uncertainty of grid connection of electric vehicle charging stations and the uncertainty of new energy and residential electricity load,a spatio-temporal decoupling strategy of dynamic reactive power optimization based on clustering-local relaxation-correction is proposed.Firstly,the k-medoids clustering algorithm is used to divide the reduced power scene into periods.Then,the discrete variables and continuous variables are optimized in the same period of time.Finally,the number of input groups of parallel capacitor banks(CB)in multiple periods is fixed,and then the secondary static reactive power optimization correction is carried out by using the continuous reactive power output device based on the static reactive power compensation device(SVC),the new energy grid-connected inverter,and the electric vehicle charging station.According to the characteristics of the model,a hybrid optimization algorithm with a cross-feedback mechanism is used to solve different types of variables,and an improved artificial hummingbird algorithm based on tent chaotic mapping and adaptive mutation is proposed to improve the solution efficiency.The simulation results show that the proposed decoupling strategy can obtain satisfactory optimization resultswhile strictly guaranteeing the dynamic constraints of discrete variables,and the hybrid algorithm can effectively solve the mixed integer nonlinear optimization problem.
基金supported by Research Grant from China Petroleum and Chemical Corp。
文摘Cu/ZnO-based catalysts are widely employed for methanol synthesis via CO_(2) hydrogenation.The preparation procedure is sensitive to the particle size and interfacial structure,which are considered as potential active centers influencing the rate of both methanol and CO formation.The particle size and the interaction between Cu and the support materials are influenced by the coprecipitation conditions,let alone that the mechanistic divergence remains unclear.In this work,a series of Cu/ZnO/ZrO_(2) catalysts were prepared via co-precipitation at different pH value and systematically characterized.The structure has been correlated with kinetic results to establish the structure-performance relationship.Kinetic analysis demonstrates that methanol synthesis follows a single-site Langmuir-Hinshelwood(L-H)mechanism,i.e.,Cu serves as the active site where CO_(2) and H_(2) competitively adsorb and react to form methanol.In contrast,CO formation proceeds via a dual-site L-H mechanism,where CO_(2) adsorbs onto ZnO and H_(2) onto Cu,with the reaction occurring at the Cu/ZnO interface.Therefore,for the direct formation of methanol,solely reducing the particle size of Cu would not be beneficial.
文摘A novel method is developed by utilizing the fractional frequency based multirange rulers to precisely position the passive inter-modulation(PIM)sources within radio frequency(RF)cables.The proposed method employs a set of fractional frequencies to create multiple measuring rulers with different metric ranges to determine the values of the tens,ones,tenths,and hundredths digits of the distance.Among these rulers,the one with the lowest frequency determines the maximum metric range,while the one with the highest frequency decides the highest achievable accuracy of the position system.For all rulers,the metric accuracy is uniquely determined by the phase accuracy of the detected PIM signals.With the all-phase Fourier transform method,the phases of the PIM signals at all fractional frequencies maintain almost the same accuracy,approximately 1°(about 1/360 wavelength in the positioning accuracy)at the signal-to-noise ratio(SNR)of 10 d B.Numerical simulations verify the effectiveness of the proposed method,improving the positioning accuracy of the cable PIM up to a millimeter level with the highest fractional frequency operating at 200 MHz.
基金supported in part by the National Key Research and Development Program under Grant(2021YFB2900300)by the National Natural Science Foundation of China(NSFC)under Grants 61971127,61871122by the Southeast University-China Mobile Research Institute Joint Innovation Center,and by the Major Key Project of PCL(PCL2021A01-2).
文摘This paper investigates how to achieve integrated sensing and communication(ISAC)based on a cell-free radio access network(CF-RAN)architecture with a minimum footprint of communication resources.We propose a new passive sensing scheme.The scheme is based on the radio frequency(RF)fingerprint learning of the RF radio unit(RRU)to build an RF fingerprint library of RRUs.The source RRU is identified by comparing the RF fingerprints carried by the signal at the receiver side.The receiver extracts the channel parameters from the signal and estimates the channel environment,thus locating the reflectors in the environment.The proposed scheme can effectively solve the problem of interference between signals in the same time-frequency domain but in different spatial domains when multiple RRUs jointly serve users in CF-RAN architecture.Simulation results show that the proposed passive ISAC scheme can effectively detect reflector location information in the environment without degrading the communication performance.
基金financial support from the General Program of the National Natural Science Foundation of China(Grant No.12474195)the Key Project of Guangdong Provincial Department of Education(Grant No.2023ZDZX3021)the Natural Science Foundation of Guangdong Province(Grant No.2024A1515011343)。
文摘In the last decade,the study of pressure in active matter has attracted growing attention due to its fundamental relevance to nonequilibrium statistical physics.Active matter systems are composed of particles that consume energy to sustain persistent motion,which are inherently far from equilibrium.These particles can exhibit complex behaviors,including motility-induced phase separation,clustering,and anomalous stress distributions,motivating the introduction of active swim stress and swim pressure.Unlike in passive fluids,pressure in active systems emerges from momentum flux originating from swim force rather than equilibrium conservative interactions,offering a distinct perspective for understanding their mechanical response.Simple models of active Brownian particles(ABPs)have been employed in theoretical and simulation studies across both dilute and dense regimes,revealing that pressure is a state function and exhibits a nontrivial dependence on density.Together with nonequilibrium statistical concepts such as effective temperature and effective adhesion,pressure offers important insight for understanding behaviors in active matter such as sedimentation equilibrium and motility induced phase separation.Extensions of ABP models beyond their simplest form have underscored the fragility of the pressure-based equation of state,which can break down under factors such as density-dependent velocity,torque,complex boundary geometries and interactions.Building on these developments,this review provides a comprehensive survey of theoretical and experimental advances,with particular emphasis on the microscopic origins of active pressure and the mechanisms underlying the breakdown of the equation of state.
基金funded by Scientific and Technological Research Project and Technology Innovation Platform Project of Huibei Provincial Department of Science and Technology(2025AFD345 and 2024CSA071)grant from Huanggang Science and Technology Bureau(ZDZX20240008)。
文摘Polygonati Rhizoma,a functional food and a traditional Chinese medicine broadly used in China and several Southeast Asia countries,possesses effective health-promoting activities.Prepared from 3 plants in Polygonatum genus(Polygonatum kingianum,Polygonatum sibiricum,and Polygonatum cyrtonema),Polygonati Rhizoma has drawn increasing attention due to its remarkable immune-enhancing and metabolic regulatory activities in recent years.In this review,we summarized the updated research of chemical constituents and biological activities of Polygonati Rhizoma,especially the metabolic regulation,immunomodulatory effects,and anti-fatigue activities,aiming to provide a comprehensive understanding,broaden the usage and promote more in-depth exploration of Polygonati Rhizoma as a functional food.
