The increasing global concern regarding plastic pollution has prompted the research into the consequences of microplastics(MPs)on aquatic ecosystems.Fairy shrimp Branchinella kugenumaensis are freshwater planktonic or...The increasing global concern regarding plastic pollution has prompted the research into the consequences of microplastics(MPs)on aquatic ecosystems.Fairy shrimp Branchinella kugenumaensis are freshwater planktonic organisms that have existed for 250 million years.This study aimed to uncover the harmful effects of MPs,with a particular focus on their size variations(0.1,1,and 5μm),on the fairy shrimp.We focused on how MPs could significantly affect the survival and growth of fairy shrimp.Notably,larger MPs,especially those measuring 5μm,caused higher mortality rates and hindered the growth compared to smaller ones.The impact of MPs continued even subsequent to depuration in clean water.The accumulation of MPs within the intestines of fairy shrimp resulted in intestinal blockages,disrupted excretory functions,and harmed intestinal epithelial cells.Examinations at the histological,cellular,and molecular levels showed that exposure to MPs triggered necroptosis in intestinal cells,accompanied by alterations in pathways related to transcription,translation,digestion,energy metabolism,and neurological functions.Furthermore,the effects of MPs on gene expression and pathways varied based on particle size,with larger MPs having a more significant effect and causing a strong response in xenobiotic biodegradation and metabolism pathways.We suggest that the increasing severity of MPs pollution could pose a significant threat to the survival of fairy shrimp.This study provided vital insights into the complex relationship between microplastics and aquatic organisms,and highlighted the urgent need to address the potential devastating impact of plastic pollution on freshwater ecosystems.Additionally,due to their rapid growth,strong reproductive capacity,sensitivity,and ease of cultivation,fairy shrimp hold the potential candidate to serve as a model organism for studying the effects of MPs and other pollutants on freshwater ecosystems.展开更多
Magnetic resonance imaging(MRI)plays an important role in precision medicine that is hampered by the lack of contrast agents with high efficiency and the ability to translate diagnostic accuracy into therapeutic inter...Magnetic resonance imaging(MRI)plays an important role in precision medicine that is hampered by the lack of contrast agents with high efficiency and the ability to translate diagnostic accuracy into therapeutic intervention.Herein,we demonstrate a DNA-based MRI probe that overcomes previous single-mode enhancement and provides a mechanism of action for aggregationinduced dual-modal MRI signal enhancement.A facile method is developed to produce aggregated T_(1)/T_(2)dual-modal NaGdF_(4):Dy@PDA-DNA(PDA=polydopamine)MRI probes.When aggregated,this probe can further amplify MRI signal intensity and exhibit improved geometrical and positional stability in vivo.The performance of the NaGdF_(4):Dy@PDA-DNA MRI probe toward MRI-guided preoperative planning and visualization-guided surgery is verified using an orthotopic tumor-bearing mouse model.The result shows that the rapid metabolism of the degraded probe leads to the mitigation of long-term toxic effects.Therefore,the developed high-performance MRI probe is of great significance for enhancing MRI diagnostic accuracy into precision medical therapeutic interventions.展开更多
0 INTRODUCTION China's external dependence on oil and gas remains high,making the independent exploration and development of oil and gas resources crucial for ensuring national energy security and the sustainable ...0 INTRODUCTION China's external dependence on oil and gas remains high,making the independent exploration and development of oil and gas resources crucial for ensuring national energy security and the sustainable development of the economy and society.In 2023,China continued to step up its efforts in offshore oil and gas exploration and development,with offshore crude oil production surpassing 62 million tons,accounting for about 70%of the national increase in crude oil production.Deepening offshore oil and gas exploration and development is of great significance for guaranteeing national energy security.展开更多
Carbon Fiber Reinforced Polymer(CFRP)composites are widely used in aircraft structures,because of their superior mechanical and lightweight properties.CFRP composites are often exposed to hygrothermal environments in ...Carbon Fiber Reinforced Polymer(CFRP)composites are widely used in aircraft structures,because of their superior mechanical and lightweight properties.CFRP composites are often exposed to hygrothermal environments in service.Temperature and moisture can affect the material properties of composites.In order to make clear the moisture diffusion behavior and the properties degradation of composites,the TG800/E207 composite laminates with four stacking sequences[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sare designed and manufactured.Moisture absorption tests are carried out at 80℃,90%RH.It is shown that the moisture absorption curves of composite laminates present a three-stage.A modified Fickian model was proposed to capture the diffusion behavior of TG800/E207 composite laminates.The relationships among the non-Fickian parameters,the environmental parameters and the stacking sequences of CFRP were correlated and compared.Results showed that the modified Fickian curve is sensitive to the diffusivity of Stage Ⅰ and Stage Ⅱ.Compared with unaged specimens,the maximum tensile stress for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 14.94%,28.15%,11.96%,and 26.36%,respectively.The strains at failure for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 55.38%,62.65%,46.41%,and31.71%,respectively.The elastic modulus for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sincreased by 90.93%,94.57%,49.22%,and 8.22%,respectively.[90]16sample has the minimum saturated moisture content and the maximum strength degeneration.展开更多
1.Introduction Due to the severe toxicity of heavy metal ions,human health and eco-system are threatened even at ultra-low concentrations[1].Specially,Pb^(2+)arouses more significant concern as its bio-accumulation se...1.Introduction Due to the severe toxicity of heavy metal ions,human health and eco-system are threatened even at ultra-low concentrations[1].Specially,Pb^(2+)arouses more significant concern as its bio-accumulation seriously affects brain development,reproductive systems,and cardiovascular function,consequently resulting in an irreversible damage.According to World Health Organization(WHO),the maximum allowable Pb^(2+)con-centration on the surface water should be<0.01 mg/L.Thus,consid-ering such deleterious and carcinogenic effects,the Pb^(2+)amount should be monitored to guarantee the water environment safety.Conventional methods always need complicate pretreatment.展开更多
Two-speed automatic transmission is one solution to increase the economic efficiency and dynamic performance of battery electric vehicles(BEV).Hydraulic control unit(HCU)is a key component in automatic transmissions,w...Two-speed automatic transmission is one solution to increase the economic efficiency and dynamic performance of battery electric vehicles(BEV).Hydraulic control unit(HCU)is a key component in automatic transmissions,which determines the quality of shifting directly.Based on the structural scheme and shift logic of a two-speed dedicated electric vehicles transmission(2DET)with two wet clutches,we designs a 2DET hydraulic control unit composed of three subsystems:pressure regulating and flow control system,shift operated and control system and cooling and lubrication system.The results of the experiments,including the valve body bench test,transmission bench test and vehicle test,show that the design of hydraulic control unit meets the requirements.展开更多
Theranostic nanoprobes can potentially integrate imaging and therapeutic capabilities into a single platform,offering a new personalized cancer diagnostic tool.However,there is a growing concern that their clinical ap...Theranostic nanoprobes can potentially integrate imaging and therapeutic capabilities into a single platform,offering a new personalized cancer diagnostic tool.However,there is a growing concern that their clinical application is not safe,particularly due to metal-containing elements,such as the gadolinium used in magnetic resonance imaging(MRI).We demonstrate for the first time that the photothermal melting of the DNA duplex helix was a reliable and versatile strategy that enables the on-demand degradation of the gadolinium-containing MRI reporter gene from polydopamine(PDA)-based theranostic nanoprobes.The combination of chemotherapy(doxorubicin)and photothermal therapy,which leads to the enhanced anti-tumor effect.In vivo MRI tracking reveals that renal filtration was able to rapidly clear the free gadolinium-containing MRI reporter from the mice body.This results in a decrease in the long-term toxic effect of theranostic MRI nanoprobes.Our findings may pave the way to address toxicity issues of the theranostic nanoprobes.展开更多
Antibacterial nanoagents with broad-spectrum antibacterial activities have emerged as an evolution of antibiotics.However,their bacteria-capturing capability and bacteria-killing efficiency remain insufficient for com...Antibacterial nanoagents with broad-spectrum antibacterial activities have emerged as an evolution of antibiotics.However,their bacteria-capturing capability and bacteria-killing efficiency remain insufficient for commercial implementation.Inspired by the hunting behavior of spiders,here,a novel spiderweb-like nanoagent based on silver-adenine nanowires is designed to achieve high-efficiency capture and killing of bacteria.By virtue of the initiative bacteriacapturing functionality,this spiderweb-like nanoagent could effectively attract and trap bacteria through electrostatic interaction and its reticular morphology feature.Furthermore,its synergetic antibacterial mechanism combining physical membranolysis with reactive oxygen species(ROS)release allows such nanoagent to harvest a promoted bactericidal activity.Importantly,the woundplast employing the spiderweblike nanoagent exhibits a superior antibacterial efficacy against drug-resistant Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus compared with commercially available woundplasts.This work may pave a new way for rational design of new generation bactericidal agents facing the future super-bacteria booming.展开更多
A high-speed motor in a drive system causes several challenges to the reliability of the mechanical parts of electric vehicles and leads to issues with noise,vibration and harshness(NVH).Thus,a two-speed powershift tr...A high-speed motor in a drive system causes several challenges to the reliability of the mechanical parts of electric vehicles and leads to issues with noise,vibration and harshness(NVH).Thus,a two-speed powershift transmission is considered an effective way to improve the dynamic,economic and comfort performance of electric vehicles.A newly designed dual-pump hydraulic control system for a two-speed powershift transmission with two wet clutches is presented,in which the mechani-cal oil pump is linearly affected by the vehicle speed and the electric oil pump is controllable.By integrating the dynamic model of the hydraulic system into one of the powertrains with a two-speed transmission,a co-simulation dynamic model is proposed.To satisfy the flow and pressure demand of the hydraulic system,a dual-pump control strategy is presented,in which the electric oil pump is controlled by the mechanical oil pump following the minimum energy consumption principle.The World Light Vehicle Test Procedure(WLTP)cycle simulation results show that the energy consumption of the proposed hydraulic system can be reduced by 58.2%compared to the previous single-pump system developed by the authors with a constant main-line pressure control strategy.On the basis,the best configuration of the two pumps can further reduce the energy consumption of the hydraulic system by 23.2%compared to that of two-oil pumps with preset displacement.展开更多
Seismic events have limited time duration,vary with space/traveltime and interact with the local subsurface medium during propagation.Partitioning is a valu-able strategy for nonstationary seismic data analysis,proces...Seismic events have limited time duration,vary with space/traveltime and interact with the local subsurface medium during propagation.Partitioning is a valu-able strategy for nonstationary seismic data analysis,processing and wave propagation.It has the potential for sparse data representation,flexible data operation and highly accurate local wave propagation.Various local transforms are powerful tools for seismic data segmentation and representation.In this paper,a detailed description of a multi-dimensional local harmonic transformed domain wave propagation and imaging method is given.Using a tensor product of a Local Exponential Frame(LEF)vector as the time-frequency atom(a drumbeat)and a Local Cosine Basis(LCB)function as the space-wavenumber atom(a beamlet),we construct a time-frequency-space-wavenumber local atom-dreamlet,which is a combination of drumbeat and beamlet.The dreamlet atoms have limited spatial extension and temporal duration and constitute a complete set of frames,termed as dreamlet frames,to decompose and represent the wavefield.The dreamlet transform first partitions the wavefields using time-space supporting functions and then the data in each time-space blocks is repre-sented by local harmonic bases.The transformed wavefield is downward-continued by the dreamlet propagator,which is the dreamlet atom evolution weightings deduced from the phase-shift one-way propagator.The dreamlet imaging method is formulated with a local background propagator for large-scale medium propagation and com-bined with a local phase-screen correction for small-scale perturbations.The features of dreamlet migration and imaging include sparse seismic data representation,accurate wave propagation and the flexibility of localized time operations during migration.Numerical tests using Sigsbee 2A synthetic data set and real marine seismic data demonstrate the validity and accuracy of this method.With time-domain localization being involved,the dreamlet method can also be applied effectively to target-oriented migration and imaging.展开更多
X-ray computed tomography(CT)imaging plays an essential role in disease diagnosis due to its noninvasive,painless mode and superior penetration depth.However,the resolution of the soft tissue and minor lesions remains...X-ray computed tomography(CT)imaging plays an essential role in disease diagnosis due to its noninvasive,painless mode and superior penetration depth.However,the resolution of the soft tissue and minor lesions remains limited.And the disadvantages of conventional contrast agents,such as their inefficient targeting capability,poor biocompatibility,and short circulation times,are considered intractable in clinical use.To overcome these“Gordian knots,”nanoparticles(NPs)for CT imaging have been developed.The advantages of NPs are their exceptionally high sensitivity to X-ray,better imaging performance in vivos and even therapeutic effects.In particular,based on various designs,NP contrast agents composed of different materials integrate multiple imaging modalities,make up for the inadequacy of a single imaging type,and thus provide more accurate information for diagnosis.This review focuses on NPs for X-ray CT imaging and their multifunctional designs.Some perspectives of crucial problems and prospective challenges are also discussed.展开更多
During the highly infectious pandemic of coronavirus disease 2019(COVID-19),artificial intelligence(AI)has provided support in addressing challenges and accelerating achievements in controlling this public health cris...During the highly infectious pandemic of coronavirus disease 2019(COVID-19),artificial intelligence(AI)has provided support in addressing challenges and accelerating achievements in controlling this public health crisis.It has been applied in fields varying from outbreak forecasting to patient management and drug/vaccine development.In this paper,we specifically review the current status of AI-based approaches for patient management.Limitations and challenges still exist,and further needs are highlighted.展开更多
基金Supported by the National Natural Science Foundation of China(Nos.32371704,32373178)。
文摘The increasing global concern regarding plastic pollution has prompted the research into the consequences of microplastics(MPs)on aquatic ecosystems.Fairy shrimp Branchinella kugenumaensis are freshwater planktonic organisms that have existed for 250 million years.This study aimed to uncover the harmful effects of MPs,with a particular focus on their size variations(0.1,1,and 5μm),on the fairy shrimp.We focused on how MPs could significantly affect the survival and growth of fairy shrimp.Notably,larger MPs,especially those measuring 5μm,caused higher mortality rates and hindered the growth compared to smaller ones.The impact of MPs continued even subsequent to depuration in clean water.The accumulation of MPs within the intestines of fairy shrimp resulted in intestinal blockages,disrupted excretory functions,and harmed intestinal epithelial cells.Examinations at the histological,cellular,and molecular levels showed that exposure to MPs triggered necroptosis in intestinal cells,accompanied by alterations in pathways related to transcription,translation,digestion,energy metabolism,and neurological functions.Furthermore,the effects of MPs on gene expression and pathways varied based on particle size,with larger MPs having a more significant effect and causing a strong response in xenobiotic biodegradation and metabolism pathways.We suggest that the increasing severity of MPs pollution could pose a significant threat to the survival of fairy shrimp.This study provided vital insights into the complex relationship between microplastics and aquatic organisms,and highlighted the urgent need to address the potential devastating impact of plastic pollution on freshwater ecosystems.Additionally,due to their rapid growth,strong reproductive capacity,sensitivity,and ease of cultivation,fairy shrimp hold the potential candidate to serve as a model organism for studying the effects of MPs and other pollutants on freshwater ecosystems.
基金supported by the National Natural Science Foundation of China(22134006,21721003,22204161,U2241287)the Natural Science Foundation of Shandong Province(ZR2020MB063)the Program of Science and Technology Development Plan of Jilin Province(20230101039JC)。
文摘Magnetic resonance imaging(MRI)plays an important role in precision medicine that is hampered by the lack of contrast agents with high efficiency and the ability to translate diagnostic accuracy into therapeutic intervention.Herein,we demonstrate a DNA-based MRI probe that overcomes previous single-mode enhancement and provides a mechanism of action for aggregationinduced dual-modal MRI signal enhancement.A facile method is developed to produce aggregated T_(1)/T_(2)dual-modal NaGdF_(4):Dy@PDA-DNA(PDA=polydopamine)MRI probes.When aggregated,this probe can further amplify MRI signal intensity and exhibit improved geometrical and positional stability in vivo.The performance of the NaGdF_(4):Dy@PDA-DNA MRI probe toward MRI-guided preoperative planning and visualization-guided surgery is verified using an orthotopic tumor-bearing mouse model.The result shows that the rapid metabolism of the degraded probe leads to the mitigation of long-term toxic effects.Therefore,the developed high-performance MRI probe is of great significance for enhancing MRI diagnostic accuracy into precision medical therapeutic interventions.
基金supported by the National Science and Technology Major Project(No.2016ZX05024)the Project of Strategic Research and Consulting Projects of the Chinese Academy of Engineering(No.2022-XBZD-08-01)。
文摘0 INTRODUCTION China's external dependence on oil and gas remains high,making the independent exploration and development of oil and gas resources crucial for ensuring national energy security and the sustainable development of the economy and society.In 2023,China continued to step up its efforts in offshore oil and gas exploration and development,with offshore crude oil production surpassing 62 million tons,accounting for about 70%of the national increase in crude oil production.Deepening offshore oil and gas exploration and development is of great significance for guaranteeing national energy security.
基金financially supported by the National Natural Science Foundation of China(Nos.91860128,12032018,and 52061135101)。
文摘Carbon Fiber Reinforced Polymer(CFRP)composites are widely used in aircraft structures,because of their superior mechanical and lightweight properties.CFRP composites are often exposed to hygrothermal environments in service.Temperature and moisture can affect the material properties of composites.In order to make clear the moisture diffusion behavior and the properties degradation of composites,the TG800/E207 composite laminates with four stacking sequences[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sare designed and manufactured.Moisture absorption tests are carried out at 80℃,90%RH.It is shown that the moisture absorption curves of composite laminates present a three-stage.A modified Fickian model was proposed to capture the diffusion behavior of TG800/E207 composite laminates.The relationships among the non-Fickian parameters,the environmental parameters and the stacking sequences of CFRP were correlated and compared.Results showed that the modified Fickian curve is sensitive to the diffusivity of Stage Ⅰ and Stage Ⅱ.Compared with unaged specimens,the maximum tensile stress for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 14.94%,28.15%,11.96%,and 26.36%,respectively.The strains at failure for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sdecreased by 55.38%,62.65%,46.41%,and31.71%,respectively.The elastic modulus for[0]16,[90]16,[±45]4s,and[(+45/0/0/-45)s]sincreased by 90.93%,94.57%,49.22%,and 8.22%,respectively.[90]16sample has the minimum saturated moisture content and the maximum strength degeneration.
基金supported by grants from the Major Program of the National Natural Science Foundation of China(No.21590813)the National Natural Science Foundation of China(No.22006039,52100128,22122807)+4 种基金the Key Project of the National Ministry of Science and Technology(No.2016YFCU204204)the Natural Science Foundation of Shandong Province(No.ZR2020QB141)the Natural Science Foundation of Shanghai(No.21ZR1425700)the China Postdoctoral Science Foundation(No.2019M661412)supported by Supercomputing Center of Dalian University of Technology.
文摘1.Introduction Due to the severe toxicity of heavy metal ions,human health and eco-system are threatened even at ultra-low concentrations[1].Specially,Pb^(2+)arouses more significant concern as its bio-accumulation seriously affects brain development,reproductive systems,and cardiovascular function,consequently resulting in an irreversible damage.According to World Health Organization(WHO),the maximum allowable Pb^(2+)con-centration on the surface water should be<0.01 mg/L.Thus,consid-ering such deleterious and carcinogenic effects,the Pb^(2+)amount should be monitored to guarantee the water environment safety.Conventional methods always need complicate pretreatment.
基金the National Natural Science Foundation of China(No.51405010)Beijing Key Laboratory for High-efficient Power Transmission and System Control of New Energy Resource Vehicles.
文摘Two-speed automatic transmission is one solution to increase the economic efficiency and dynamic performance of battery electric vehicles(BEV).Hydraulic control unit(HCU)is a key component in automatic transmissions,which determines the quality of shifting directly.Based on the structural scheme and shift logic of a two-speed dedicated electric vehicles transmission(2DET)with two wet clutches,we designs a 2DET hydraulic control unit composed of three subsystems:pressure regulating and flow control system,shift operated and control system and cooling and lubrication system.The results of the experiments,including the valve body bench test,transmission bench test and vehicle test,show that the design of hydraulic control unit meets the requirements.
基金supported by the National Natural Science Foundation of China(21635007 and 21605137)the National Key Research and Development Program of China(2016YFA0203200)+2 种基金Natural Science Foundation of Shandong Province(2018GGX102030)Taishan Scholar Program of Shandong Province(ts201511027)K.C.Wong Education Foundation。
文摘Theranostic nanoprobes can potentially integrate imaging and therapeutic capabilities into a single platform,offering a new personalized cancer diagnostic tool.However,there is a growing concern that their clinical application is not safe,particularly due to metal-containing elements,such as the gadolinium used in magnetic resonance imaging(MRI).We demonstrate for the first time that the photothermal melting of the DNA duplex helix was a reliable and versatile strategy that enables the on-demand degradation of the gadolinium-containing MRI reporter gene from polydopamine(PDA)-based theranostic nanoprobes.The combination of chemotherapy(doxorubicin)and photothermal therapy,which leads to the enhanced anti-tumor effect.In vivo MRI tracking reveals that renal filtration was able to rapidly clear the free gadolinium-containing MRI reporter from the mice body.This results in a decrease in the long-term toxic effect of theranostic MRI nanoprobes.Our findings may pave the way to address toxicity issues of the theranostic nanoprobes.
基金supported by the National Natural Science Foundation of China(21703230,21635007 and 21721003)K.C.Wong Education Foundation。
文摘Antibacterial nanoagents with broad-spectrum antibacterial activities have emerged as an evolution of antibiotics.However,their bacteria-capturing capability and bacteria-killing efficiency remain insufficient for commercial implementation.Inspired by the hunting behavior of spiders,here,a novel spiderweb-like nanoagent based on silver-adenine nanowires is designed to achieve high-efficiency capture and killing of bacteria.By virtue of the initiative bacteriacapturing functionality,this spiderweb-like nanoagent could effectively attract and trap bacteria through electrostatic interaction and its reticular morphology feature.Furthermore,its synergetic antibacterial mechanism combining physical membranolysis with reactive oxygen species(ROS)release allows such nanoagent to harvest a promoted bactericidal activity.Importantly,the woundplast employing the spiderweblike nanoagent exhibits a superior antibacterial efficacy against drug-resistant Gram-negative Escherichia coli and Gram-positive methicillin-resistant Staphylococcus aureus compared with commercially available woundplasts.This work may pave a new way for rational design of new generation bactericidal agents facing the future super-bacteria booming.
基金This work is financially supported by National Natural Science Foundation of China(Grant Number:52072018)Key Science and Technology Innovation Project of Shandong Province(Grant Number:2020CXG011004)+1 种基金2025 Science and Technology Innovation Program of Ningbo(Grant Number:2020Z026)The authors also acknowledge the support of Beijing Key Laboratory for High-efficient Power Transmission and System Control of New Energy Resource Vehicle and the support of the Fundamental Research Funds for the Central Universities。
文摘A high-speed motor in a drive system causes several challenges to the reliability of the mechanical parts of electric vehicles and leads to issues with noise,vibration and harshness(NVH).Thus,a two-speed powershift transmission is considered an effective way to improve the dynamic,economic and comfort performance of electric vehicles.A newly designed dual-pump hydraulic control system for a two-speed powershift transmission with two wet clutches is presented,in which the mechani-cal oil pump is linearly affected by the vehicle speed and the electric oil pump is controllable.By integrating the dynamic model of the hydraulic system into one of the powertrains with a two-speed transmission,a co-simulation dynamic model is proposed.To satisfy the flow and pressure demand of the hydraulic system,a dual-pump control strategy is presented,in which the electric oil pump is controlled by the mechanical oil pump following the minimum energy consumption principle.The World Light Vehicle Test Procedure(WLTP)cycle simulation results show that the energy consumption of the proposed hydraulic system can be reduced by 58.2%compared to the previous single-pump system developed by the authors with a constant main-line pressure control strategy.On the basis,the best configuration of the two pumps can further reduce the energy consumption of the hydraulic system by 23.2%compared to that of two-oil pumps with preset displacement.
基金supported by the National Natural Science Foundation of China(41604106,41674123,11871392)the Fundamental Research Funds for the Center Universities(xjj2018260)+1 种基金the China Postdoctoral Foundation(2016M600780)WTOPI(Wavelet Transform On Propagation and Imaging for seismic exploration)Project at University of California,Santa Cruz.
文摘Seismic events have limited time duration,vary with space/traveltime and interact with the local subsurface medium during propagation.Partitioning is a valu-able strategy for nonstationary seismic data analysis,processing and wave propagation.It has the potential for sparse data representation,flexible data operation and highly accurate local wave propagation.Various local transforms are powerful tools for seismic data segmentation and representation.In this paper,a detailed description of a multi-dimensional local harmonic transformed domain wave propagation and imaging method is given.Using a tensor product of a Local Exponential Frame(LEF)vector as the time-frequency atom(a drumbeat)and a Local Cosine Basis(LCB)function as the space-wavenumber atom(a beamlet),we construct a time-frequency-space-wavenumber local atom-dreamlet,which is a combination of drumbeat and beamlet.The dreamlet atoms have limited spatial extension and temporal duration and constitute a complete set of frames,termed as dreamlet frames,to decompose and represent the wavefield.The dreamlet transform first partitions the wavefields using time-space supporting functions and then the data in each time-space blocks is repre-sented by local harmonic bases.The transformed wavefield is downward-continued by the dreamlet propagator,which is the dreamlet atom evolution weightings deduced from the phase-shift one-way propagator.The dreamlet imaging method is formulated with a local background propagator for large-scale medium propagation and com-bined with a local phase-screen correction for small-scale perturbations.The features of dreamlet migration and imaging include sparse seismic data representation,accurate wave propagation and the flexibility of localized time operations during migration.Numerical tests using Sigsbee 2A synthetic data set and real marine seismic data demonstrate the validity and accuracy of this method.With time-domain localization being involved,the dreamlet method can also be applied effectively to target-oriented migration and imaging.
基金The authors gratefully acknowledge the financial support received from the National Natural Science Foundation of China(nos.21721003 and 21635007)and the K.C.Wong Education Foundation.
文摘X-ray computed tomography(CT)imaging plays an essential role in disease diagnosis due to its noninvasive,painless mode and superior penetration depth.However,the resolution of the soft tissue and minor lesions remains limited.And the disadvantages of conventional contrast agents,such as their inefficient targeting capability,poor biocompatibility,and short circulation times,are considered intractable in clinical use.To overcome these“Gordian knots,”nanoparticles(NPs)for CT imaging have been developed.The advantages of NPs are their exceptionally high sensitivity to X-ray,better imaging performance in vivos and even therapeutic effects.In particular,based on various designs,NP contrast agents composed of different materials integrate multiple imaging modalities,make up for the inadequacy of a single imaging type,and thus provide more accurate information for diagnosis.This review focuses on NPs for X-ray CT imaging and their multifunctional designs.Some perspectives of crucial problems and prospective challenges are also discussed.
基金This research was funded by National Key Research and Development Program of China(Grant No.2020YFC0845500).
文摘During the highly infectious pandemic of coronavirus disease 2019(COVID-19),artificial intelligence(AI)has provided support in addressing challenges and accelerating achievements in controlling this public health crisis.It has been applied in fields varying from outbreak forecasting to patient management and drug/vaccine development.In this paper,we specifically review the current status of AI-based approaches for patient management.Limitations and challenges still exist,and further needs are highlighted.