We read with great interest Deng et al.’s study 1 comparing sextant(6-core)and 12-core systematic biopsy in theMRI-targeted era,which valuably challenges the“more cores=higher accuracy”dogma by proposing a precisio...We read with great interest Deng et al.’s study 1 comparing sextant(6-core)and 12-core systematic biopsy in theMRI-targeted era,which valuably challenges the“more cores=higher accuracy”dogma by proposing a precision sampling strategy based on prostate cancer’s spatial distribution,aligning with personalized diagnosis trends.展开更多
The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,t...The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,the InSight lander collected long-term marsquake data,which improved the Martian interior structure model.B ased on the preliminary analysis of marsquake data,Mars has a molten liquid core with a radius of around 1700 km.As the Martian core has a smaller density and lower temperature than pure iron at corresponding pressure and temperature conditions,some light elements are introduced to reduce the density and liquidus temperature.With various methods for seismic analysis,in-situ high-pressure and high-temperature experiments,and first-principal calculations,the Martian core composition and evolution models have been updated in the past few years.Here,we review those studies on the light elements in the Martian core from four aspects including(1)high-temperature and high-pressure experiments,(2)marsquake data,(3)mineral physics model with molecular dynamics simulations and(4)cosmochemistry investigation.We discussed the effect of different light elements on the Martian core s density,sound velocity and liquidus temperature.Moreover,the review examines the varieties,abundances and forms of light elements in the Martian core.展开更多
Portable ratiometric fluorescent platforms have emerged as promising tools for multifarious detection,yet remain unexplored for point-of-care monitoring doxorubicin(DOX),one of clinically antineoplastic drugs.To this ...Portable ratiometric fluorescent platforms have emerged as promising tools for multifarious detection,yet remain unexplored for point-of-care monitoring doxorubicin(DOX),one of clinically antineoplastic drugs.To this end,we herein develop a portable self-calibrating platform namely carbon dots(C-dots)-embedded hydrogel sensors with a smartphone-assisted high-throughput imaging device,for DOX sensing.The prepared green-emitting(λ_(em)=508 nm)and negatively-charged C-dots(−11.40±1.21 mV),which have sufficient spectral overlap with the absorption band of DOX(∼500 nm),can strongly bind with positively-charged DOX molecules by electrostatic attraction effects.As a result,DOX molecules are selectively and rapid(20 s)determined with a detection limit of 10.26 nmol/L via Förster resonance energy transfer processes,demonstrating a remarkably chromatic shift from green to red.Further integrated with a 3D-printed smartphone-assisted device,the platform enabled high-throughput quantification,achieving recoveries of 96.40%-101.85%in human urine/serum(RSDs<2.94%,n=3).Notably,the dual linear detection ranges of the platform align with the reported clinical DOX concentrations in urine and plasma(0-4 h post-administration),validating their capability for direct quantification of DOX in clinical samples without special pre-treatment processes.By virtue of attractive analytical performances and robust feasibility,this platform bridges laboratory precision and point-of-care testing needs,offering promising potential for personalized chemotherapy and multiplexed analyte screening.展开更多
[Objectives]To investigate the clinical efficacy of core stability training combined with conventional rehabilitation in the functional recovery of patients suffering from chronic low back pain.[Methods]A randomized c...[Objectives]To investigate the clinical efficacy of core stability training combined with conventional rehabilitation in the functional recovery of patients suffering from chronic low back pain.[Methods]A randomized controlled trial design was employed in this study.Ninety patients with chronic low back pain were recruited and randomly assigned to either a control group(n=45),which received conventional rehabilitation,or an experimental group(n=45),which received conventional rehabilitation combined with core stability training.Both groups underwent treatment for 6 weeks.Assessments were conducted using the visual analogue scale(VAS),Oswestry disability index(ODI),and finger-to-floor test prior to treatment,6 weeks following treatment,and during the follow-up period,respectively.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups in terms of general information and various baseline measurements(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups demonstrated significant improvements in VAS scores,ODI scores,and lumbar anteflexion range of motion compared to baseline measurements(P<0.05).Notably,the magnitude of improvement in the experimental group exceeded that of the control group,with this inter-group difference reaching statistical significance(P<0.05).No serious adverse reactions were reported during the treatment process.[Conclusions]Core stability training combined with conventional rehabilitation can significantly enhance the alleviation of pain and functional impairments in patients suffering from chronic low back pain.This approach holds valuable implications for the optimization of rehabilitation treatment protocols.展开更多
As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing pl...As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing planetary habitability and the search for extraterrestrial life.The integrated measurement of N_(2)and argon(Ar)isotopes by using noble gas mass spectrometry represents a state-of-the-art technique for such investigations.To support the growing demands of planetary science research in China,we have developed a high-efficiency,high-precision method for the integrated analysis of N_(2)and Ar isotopes.This was achieved by enhancing gas extraction and purification systems and integrating them with a static noble gas mass spectrometer.This method enables integrated N_(2)-Ar isotope measurements on submilligram samples,significantly improving sample utilization and reducing the impact of sample heterogeneity on volatile analysis.The system integrates CO_(2)laser heating,a modular two-stage Zr-Al getter pump,and a CuO furnace-based purification process,effectively reducing background levels(N_(2)blank as low as 0.35×10^(−6)cubic centimeters at standard temperature and pressure[ccSTP]).Analytical precision is ensured through calibration with atmospheric air and CO corrections.To validate the reliability of the method,we performed N_(2)-Ar isotope analyses on the Allende carbonaceous chondrite,one of the most extensively studied meteorites internationally.The measured N_(2)concentrations range from 19.2 to 29.8 ppm,withδ15N values between−44.8‰and−33.0‰.Concentrations of 40Ar,36Ar,and 38Ar are(12.5-21.1)×10^(−6)ccSTP/g,(90.9-150.3)×10^(−9)ccSTP/g,and(19.2-30.7)×10^(−9)ccSTP/g,respectively.These values correspond to cosmic-ray exposure ages of 4.5-5.7 Ma,consistent with previous reports.Step-heating experiments further reveal distinct release patterns of N and Ar isotopes,as well as their associations with specific mineral phases in the meteorite.In summary,the combined N_(2)-Ar isotopic system offers significant advantages for tracing volatile sources in extraterrestrial materials and will provide essential analytical support for upcoming Chinese planetary missions,such as Tianwen-2.展开更多
Graph Neural Networks(GNNs),as a deep learning framework specifically designed for graph-structured data,have achieved deep representation learning of graph data through message passing mechanisms and have become a co...Graph Neural Networks(GNNs),as a deep learning framework specifically designed for graph-structured data,have achieved deep representation learning of graph data through message passing mechanisms and have become a core technology in the field of graph analysis.However,current reviews on GNN models are mainly focused on smaller domains,and there is a lack of systematic reviews on the classification and applications of GNN models.This review systematically synthesizes the three canonical branches of GNN,Graph Convolutional Network(GCN),Graph Attention Network(GAT),and Graph Sampling Aggregation Network(GraphSAGE),and analyzes their integration pathways from both structural and feature perspectives.Drawing on representative studies,we identify three major integration patterns:cascaded fusion,where heterogeneous modules such as Convolutional Neural Network(CNN),Long Short-Term Memory(LSTM),and GraphSAGE are sequentially combined for hierarchical feature learning;parallel fusion,where multi-branch architectures jointly encode complementary graph features;and feature-level fusion,which employs concatenation,weighted summation,or attention-based gating to adaptively merge multi-source embeddings.Through these patterns,integrated GNNs achieve enhanced expressiveness,robustness,and scalability across domains including transportation,biomedicine,and cybersecurity.展开更多
Nutrient release from the dredged and undredged sediments in Lake Kasumigaura were simulated under the laboratory control conditions with large-size core samples. It was found that phosphate and ammonia release fluxes...Nutrient release from the dredged and undredged sediments in Lake Kasumigaura were simulated under the laboratory control conditions with large-size core samples. It was found that phosphate and ammonia release fluxes are less in aerobic than those in anaerobic. In different simulated dredged depth, the phosphate release showed large divergence in the anaerobic than in the aerobic. There was a larger accumulated release of phosphate and ammonia at actual dredged (St. B) than the undredged (St. A) in anaerobic condition. This showed that the sludge-dredging was effective of controlling phosphorus and nitrogen release. A preliminary assessment is drawn from the experiments that the sludge-dredging work in Tsuchiura Bay of Lake Kasumigaura can reduce about 15. 9% of phospbate and 56. 2% of anunonia release from the sediments respectively.展开更多
An on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry method for the analysis of perfluoroalkyl substances（PFASs） in water samples was developed.The optimal analytical con...An on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry method for the analysis of perfluoroalkyl substances（PFASs） in water samples was developed.The optimal analytical conditions were obtained through the optimization of the extraction efficiency of online solid phase extraction column,sample loading rate and loading volume,and the concentration of ammonium acetate in mobile phase.Under the optimal condition,the analytical method displayed good linearity（r^2〉0.99） for 12 PFASs（C5-C14 perfluoroalkyl carboxylic acids and C6/C8 perfluoroalkyl sulfonic acids） over a concentration range of 0.5-100 ng/L.The limits of quantitation for samples were between 0.025 ng/L and 0.5 ng/L and the relative standard deviations（RSD） of five consecutive analyses were less than 10%for 1 ng/L standard solution.Satisfactory results were obtained using this analytical method for the analysis of perfluoroalkyl substances in Antarctic ice core samples.The recoveries of all perfluoroalkyl substances were in a range of 73%-117%when the samples were spiked with standards at the concentrations of 2.5 ng/L and 25 ng/L.展开更多
Dust phenomenon is one of the biggest environmental problems in arid and semiarid regions. In these areas, lakes and wetlands are natural dust traps and core sampling method can be an appropriate way to assess the phe...Dust phenomenon is one of the biggest environmental problems in arid and semiarid regions. In these areas, lakes and wetlands are natural dust traps and core sampling method can be an appropriate way to assess the phenomenon of the dust. Therefore, the purpose of this study is the study of frequency and characteristics of dust sediments in core samples from Hashilan wetlands, Kermanshah. Four intact core samples were taken from different parts of the Hashilan wetland in Kermanshah. Physical, chemical and micromorphological analysis were done. Also clay mineralogy was performed using X-ray analysis (XRD) and shape of particles was photographed by scanning electron microscope (SEM). Considering that four samples had been taken from different parts of the wetland, the quantitative differences in dust amount are likely due to the location of the samples. The results of XRD and thin sections show that the dominant mineralogical composition of dust particles was clay minerals, quartz and calcite. SEM results for core sample 1 revealed that most particles had the size between 2 to 50 mm which ranged from fine silt to coarse silt. Considering the similarities between SEM images for core sample 1 and those from Kermanshah dust measurement station, it could be said that fine rounded particles detected at top 30 cm of core samples had Aeolian origin. These findings were in accordance with the results from dust measurement and weather station of Kermanshah about increased dust activities in the study area over past 10 years.展开更多
Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression an...Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.展开更多
The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large de...The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large deformation during the LCR process and to minimize the thickness of the slab in bending segments,the maximum theoretical reduction amount and the corresponding reduction scheme for the LCR process must be determined.With SPA-H weathering steel as a specific research steel grade,the distributions of tem-perature and deformation fields of a slab with the LCR process were analyzed using a three-dimensional thermal-mechanical finite ele-ment model.High-temperature tensile tests were designed to determine the critical strain of corner crack propagation and intermediate crack initiation with various strain rates and temperatures,and a prediction model of the critical strain for two typical cracks,combining the effects of strain rate and temperature,was proposed by incorporating the Zener-Hollomon parameter.The crack risks with different LCR schemes were calculated using the crack risk prediction model,and the maximum theoretical reduction amount for the SPA-H slab with a transverse section of 145 mm×1600 mm was 41.8 mm,with corresponding reduction amounts for Segment 0 to Segment 4 of 15.8,7.3,6.5,6.4,and 5.8 mm,respectively.展开更多
Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of...Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.展开更多
For the first time,the linear and nonlinear vibrations of composite rectangular sandwich plates with various geometric patterns of lattice core have been analytically examined in this work.The plate comprises a lattic...For the first time,the linear and nonlinear vibrations of composite rectangular sandwich plates with various geometric patterns of lattice core have been analytically examined in this work.The plate comprises a lattice core located in the middle and several homogeneous orthotropic layers that are symmetrical relative to it.For this purpose,the partial differential equations of motion have been derived based on the first-order shear deformation theory,employing Hamilton’s principle and Von Kármán’s nonlinear displacement-strain relations.Then,the nonlinear partial differential equations of the plate are converted into a time-dependent nonlinear ordinary differential equation(Duffing equation)by applying the Galerkin method.From the solution of this equation,the natural frequencies are extracted.Then,to calculate the non-linear frequencies of the plate,the non-linear equation of the plate has been solved analytically using the method of multiple scales.Finally,the effect of some critical parameters of the system,such as the thickness,height,and different angles of the stiffeners on the linear and nonlinear frequencies,has been analyzed in detail.To confirmthe solution method,the results of this research have been compared with the reported results in the literature and finite elements in ABAQUS,and a perfect match is observed.The results reveal that the geometry and configuration of core ribs strongly affect the natural frequencies of the plate.展开更多
在现有的工业系统中,利用无监督算法进行工业场景的结构异常检测是一种非常重要的手段。针对现有无监督异常检测模型对离群正常特征的低敏特性,提出一种基于PatchCore改进的无监督异常检测模型。首先,引入无监督聚类算法对其核心特征集...在现有的工业系统中,利用无监督算法进行工业场景的结构异常检测是一种非常重要的手段。针对现有无监督异常检测模型对离群正常特征的低敏特性,提出一种基于PatchCore改进的无监督异常检测模型。首先,引入无监督聚类算法对其核心特征集进行聚类采样,以降低算法对离群的正常特征的敏感度。其次,以余弦相似度作为度量标准,仅考虑特征向量方向的相似性,从而消除正常特征向量内异常值导致欧式距离异常的影响。最后,在MVTec LOCO AD和MVTec AD数据集上分别进行验证。实验结果表明,改进的PatchCore模型在MVTec LOCO AD和MVTec AD数据集上的图像级AUROC和像素级AUROC得分分别达到0.876和0.860,与PatchCore模型相比,分别提升了5.1%和3.7%。展开更多
Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experime...Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing,digital core technology,and theoretical modelling.Two CRL types with contrasting mesostructures were characterized across three scales.Macroscopically,CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa,respectively.Mesoscopically,CRL-I featured small-scale highly interconnected pores,whilst CRL-II developed larger stratified pores with diminished connectivity.Microscopically,both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties.A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes,revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II.Furthermore,a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior.These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.展开更多
Core power is a key parameter of nuclear reactor.Traditionally,the proportional-integralderivative(PID)controllers are used to control the core power.Fractional-order PID(FOPID)controller represents the cutting edge i...Core power is a key parameter of nuclear reactor.Traditionally,the proportional-integralderivative(PID)controllers are used to control the core power.Fractional-order PID(FOPID)controller represents the cutting edge in core power control research.In comparing with the integer-order models,fractional-order models describe the variation of core power more accurately,thus provide a comprehensive and realistic depiction for the power and state changes of reactor core.However,current fractional-order controllers cannot adjust their parameters dynamically to response the environmental changes or demands.In this paper,we aim at the stable control and dynamic responsiveness of core power.Based on the strong selflearning ability of artificial neural network(ANN),we propose a composite controller combining the ANN and FOPID controller.The FOPID controller is firstly designed and a back propagation neural network(BPNN)is then utilized to optimize the parameters of FOPID.It is shown by simulation that the composite controller enables the real-time parameter tuning via ANN and retains the advantage of FOPID controller.展开更多
文摘We read with great interest Deng et al.’s study 1 comparing sextant(6-core)and 12-core systematic biopsy in theMRI-targeted era,which valuably challenges the“more cores=higher accuracy”dogma by proposing a precision sampling strategy based on prostate cancer’s spatial distribution,aligning with personalized diagnosis trends.
基金financially supported by the National Natural Science Foundation of China(grant no.42120104005)Guizhou Provincial 2021 Science and Technology Subsidies(grant no.GZ2021SIG)+1 种基金Guizhou Provincial Science and Technology Projects(grant nos.ZK[2024]087GCC[2023]060)。
文摘The Martian core mainly contains iron,nickel and some light elements.However,controversies remain about the structure and chemical composition of the Martian core due to a lack of samples and marsquake data.Recently,the InSight lander collected long-term marsquake data,which improved the Martian interior structure model.B ased on the preliminary analysis of marsquake data,Mars has a molten liquid core with a radius of around 1700 km.As the Martian core has a smaller density and lower temperature than pure iron at corresponding pressure and temperature conditions,some light elements are introduced to reduce the density and liquidus temperature.With various methods for seismic analysis,in-situ high-pressure and high-temperature experiments,and first-principal calculations,the Martian core composition and evolution models have been updated in the past few years.Here,we review those studies on the light elements in the Martian core from four aspects including(1)high-temperature and high-pressure experiments,(2)marsquake data,(3)mineral physics model with molecular dynamics simulations and(4)cosmochemistry investigation.We discussed the effect of different light elements on the Martian core s density,sound velocity and liquidus temperature.Moreover,the review examines the varieties,abundances and forms of light elements in the Martian core.
基金supported by the National NaturalScience Foundation of China(No.22274001)the Key Project of Natural Science Research of the Education Department of Anhui Province(No.2022AH051032)the Excellent Research and Innovation Team of Universities in Anhui Province(No.2024AH010016).
文摘Portable ratiometric fluorescent platforms have emerged as promising tools for multifarious detection,yet remain unexplored for point-of-care monitoring doxorubicin(DOX),one of clinically antineoplastic drugs.To this end,we herein develop a portable self-calibrating platform namely carbon dots(C-dots)-embedded hydrogel sensors with a smartphone-assisted high-throughput imaging device,for DOX sensing.The prepared green-emitting(λ_(em)=508 nm)and negatively-charged C-dots(−11.40±1.21 mV),which have sufficient spectral overlap with the absorption band of DOX(∼500 nm),can strongly bind with positively-charged DOX molecules by electrostatic attraction effects.As a result,DOX molecules are selectively and rapid(20 s)determined with a detection limit of 10.26 nmol/L via Förster resonance energy transfer processes,demonstrating a remarkably chromatic shift from green to red.Further integrated with a 3D-printed smartphone-assisted device,the platform enabled high-throughput quantification,achieving recoveries of 96.40%-101.85%in human urine/serum(RSDs<2.94%,n=3).Notably,the dual linear detection ranges of the platform align with the reported clinical DOX concentrations in urine and plasma(0-4 h post-administration),validating their capability for direct quantification of DOX in clinical samples without special pre-treatment processes.By virtue of attractive analytical performances and robust feasibility,this platform bridges laboratory precision and point-of-care testing needs,offering promising potential for personalized chemotherapy and multiplexed analyte screening.
文摘[Objectives]To investigate the clinical efficacy of core stability training combined with conventional rehabilitation in the functional recovery of patients suffering from chronic low back pain.[Methods]A randomized controlled trial design was employed in this study.Ninety patients with chronic low back pain were recruited and randomly assigned to either a control group(n=45),which received conventional rehabilitation,or an experimental group(n=45),which received conventional rehabilitation combined with core stability training.Both groups underwent treatment for 6 weeks.Assessments were conducted using the visual analogue scale(VAS),Oswestry disability index(ODI),and finger-to-floor test prior to treatment,6 weeks following treatment,and during the follow-up period,respectively.[Results]Prior to treatment,no statistically significant differences were observed between the two patient groups in terms of general information and various baseline measurements(P>0.05).Following 6 weeks of treatment and throughout the follow-up period,both groups demonstrated significant improvements in VAS scores,ODI scores,and lumbar anteflexion range of motion compared to baseline measurements(P<0.05).Notably,the magnitude of improvement in the experimental group exceeded that of the control group,with this inter-group difference reaching statistical significance(P<0.05).No serious adverse reactions were reported during the treatment process.[Conclusions]Core stability training combined with conventional rehabilitation can significantly enhance the alleviation of pain and functional impairments in patients suffering from chronic low back pain.This approach holds valuable implications for the optimization of rehabilitation treatment protocols.
基金supported by the Bureau of Frontier Sciences and Basic Research,Chinese Academy of Sciences(Grant No.QYJ-2025-0103)the National Natural Science Foundation of China(Grant Nos.42441834,42241105,42441825,and 42203048)the Key Research Program of the Institute of Geology and Geophysics,Chinese Academy of Sciences(Grant No.IGGCAS-202401).
文摘As one of the major volatile components in extraterrestrial materials,nitrogen(N_(2))isotopes serve not only as tracers for the formation and evolution of the solar system,but also play a critical role in assessing planetary habitability and the search for extraterrestrial life.The integrated measurement of N_(2)and argon(Ar)isotopes by using noble gas mass spectrometry represents a state-of-the-art technique for such investigations.To support the growing demands of planetary science research in China,we have developed a high-efficiency,high-precision method for the integrated analysis of N_(2)and Ar isotopes.This was achieved by enhancing gas extraction and purification systems and integrating them with a static noble gas mass spectrometer.This method enables integrated N_(2)-Ar isotope measurements on submilligram samples,significantly improving sample utilization and reducing the impact of sample heterogeneity on volatile analysis.The system integrates CO_(2)laser heating,a modular two-stage Zr-Al getter pump,and a CuO furnace-based purification process,effectively reducing background levels(N_(2)blank as low as 0.35×10^(−6)cubic centimeters at standard temperature and pressure[ccSTP]).Analytical precision is ensured through calibration with atmospheric air and CO corrections.To validate the reliability of the method,we performed N_(2)-Ar isotope analyses on the Allende carbonaceous chondrite,one of the most extensively studied meteorites internationally.The measured N_(2)concentrations range from 19.2 to 29.8 ppm,withδ15N values between−44.8‰and−33.0‰.Concentrations of 40Ar,36Ar,and 38Ar are(12.5-21.1)×10^(−6)ccSTP/g,(90.9-150.3)×10^(−9)ccSTP/g,and(19.2-30.7)×10^(−9)ccSTP/g,respectively.These values correspond to cosmic-ray exposure ages of 4.5-5.7 Ma,consistent with previous reports.Step-heating experiments further reveal distinct release patterns of N and Ar isotopes,as well as their associations with specific mineral phases in the meteorite.In summary,the combined N_(2)-Ar isotopic system offers significant advantages for tracing volatile sources in extraterrestrial materials and will provide essential analytical support for upcoming Chinese planetary missions,such as Tianwen-2.
基金funded by Guangzhou Huashang University(2024HSZD01,HS2023JYSZH01).
文摘Graph Neural Networks(GNNs),as a deep learning framework specifically designed for graph-structured data,have achieved deep representation learning of graph data through message passing mechanisms and have become a core technology in the field of graph analysis.However,current reviews on GNN models are mainly focused on smaller domains,and there is a lack of systematic reviews on the classification and applications of GNN models.This review systematically synthesizes the three canonical branches of GNN,Graph Convolutional Network(GCN),Graph Attention Network(GAT),and Graph Sampling Aggregation Network(GraphSAGE),and analyzes their integration pathways from both structural and feature perspectives.Drawing on representative studies,we identify three major integration patterns:cascaded fusion,where heterogeneous modules such as Convolutional Neural Network(CNN),Long Short-Term Memory(LSTM),and GraphSAGE are sequentially combined for hierarchical feature learning;parallel fusion,where multi-branch architectures jointly encode complementary graph features;and feature-level fusion,which employs concatenation,weighted summation,or attention-based gating to adaptively merge multi-source embeddings.Through these patterns,integrated GNNs achieve enhanced expressiveness,robustness,and scalability across domains including transportation,biomedicine,and cybersecurity.
文摘Nutrient release from the dredged and undredged sediments in Lake Kasumigaura were simulated under the laboratory control conditions with large-size core samples. It was found that phosphate and ammonia release fluxes are less in aerobic than those in anaerobic. In different simulated dredged depth, the phosphate release showed large divergence in the anaerobic than in the aerobic. There was a larger accumulated release of phosphate and ammonia at actual dredged (St. B) than the undredged (St. A) in anaerobic condition. This showed that the sludge-dredging was effective of controlling phosphorus and nitrogen release. A preliminary assessment is drawn from the experiments that the sludge-dredging work in Tsuchiura Bay of Lake Kasumigaura can reduce about 15. 9% of phospbate and 56. 2% of anunonia release from the sediments respectively.
基金supported by the National Natural Science Foundation of China(Nos.21377145,21321004)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB01020300)
文摘An on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry method for the analysis of perfluoroalkyl substances（PFASs） in water samples was developed.The optimal analytical conditions were obtained through the optimization of the extraction efficiency of online solid phase extraction column,sample loading rate and loading volume,and the concentration of ammonium acetate in mobile phase.Under the optimal condition,the analytical method displayed good linearity（r^2〉0.99） for 12 PFASs（C5-C14 perfluoroalkyl carboxylic acids and C6/C8 perfluoroalkyl sulfonic acids） over a concentration range of 0.5-100 ng/L.The limits of quantitation for samples were between 0.025 ng/L and 0.5 ng/L and the relative standard deviations（RSD） of five consecutive analyses were less than 10%for 1 ng/L standard solution.Satisfactory results were obtained using this analytical method for the analysis of perfluoroalkyl substances in Antarctic ice core samples.The recoveries of all perfluoroalkyl substances were in a range of 73%-117%when the samples were spiked with standards at the concentrations of 2.5 ng/L and 25 ng/L.
文摘Dust phenomenon is one of the biggest environmental problems in arid and semiarid regions. In these areas, lakes and wetlands are natural dust traps and core sampling method can be an appropriate way to assess the phenomenon of the dust. Therefore, the purpose of this study is the study of frequency and characteristics of dust sediments in core samples from Hashilan wetlands, Kermanshah. Four intact core samples were taken from different parts of the Hashilan wetland in Kermanshah. Physical, chemical and micromorphological analysis were done. Also clay mineralogy was performed using X-ray analysis (XRD) and shape of particles was photographed by scanning electron microscope (SEM). Considering that four samples had been taken from different parts of the wetland, the quantitative differences in dust amount are likely due to the location of the samples. The results of XRD and thin sections show that the dominant mineralogical composition of dust particles was clay minerals, quartz and calcite. SEM results for core sample 1 revealed that most particles had the size between 2 to 50 mm which ranged from fine silt to coarse silt. Considering the similarities between SEM images for core sample 1 and those from Kermanshah dust measurement station, it could be said that fine rounded particles detected at top 30 cm of core samples had Aeolian origin. These findings were in accordance with the results from dust measurement and weather station of Kermanshah about increased dust activities in the study area over past 10 years.
基金financially supported by the National Natural Science Foundation of China(Nos.42272153 and 42472195)the Research Fund of PetroChina Tarim Oilfield Company(No.671023060003)the Research Fund of China National Petroleum Corporation Limited(No.2023ZZ16YJ04).
文摘Deep tight reservoirs exhibit complex stress and seepage fields due to varying pore structures,thus the seepage characteristics are significant for enhancing oil production.This study conducted triaxial compression and permeability tests to investigate the mechanical and seepage properties of tight sandstone.A digital core of tight sandstone was built using Computed Tomography(CT)scanning,which was divided into matrix and pore phases by a pore equivalent diameter threshold.A fluid-solid coupling model was established to investigate the seepage characteristics at micro-scale.The results showed that increasing the confining pressure decreased porosity,permeability,and flow velocity,with the pore phase becoming the dominant seepage channel.Cracks and large pores closed first under increasing pressure,resulted in a steep drop in permeability.However,permeability slightly decreased under high confining pressure,which followed a first-order exponential function.Flow velocity increased with seepage pressure.And the damage mainly occurred in stress-concentration regions under low seepage pressure.Seepage behavior followed linear Darcy flow,the damage emerged at seepage entrances under high pressure,which decreased rock elastic modulus and significantly increased permeability.
基金supported by the National Natural Science Foundation of China(No.52474355)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project),China(Nos.2022JH25/10200003 and 2023JH2/101800058).
文摘The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large deformation during the LCR process and to minimize the thickness of the slab in bending segments,the maximum theoretical reduction amount and the corresponding reduction scheme for the LCR process must be determined.With SPA-H weathering steel as a specific research steel grade,the distributions of tem-perature and deformation fields of a slab with the LCR process were analyzed using a three-dimensional thermal-mechanical finite ele-ment model.High-temperature tensile tests were designed to determine the critical strain of corner crack propagation and intermediate crack initiation with various strain rates and temperatures,and a prediction model of the critical strain for two typical cracks,combining the effects of strain rate and temperature,was proposed by incorporating the Zener-Hollomon parameter.The crack risks with different LCR schemes were calculated using the crack risk prediction model,and the maximum theoretical reduction amount for the SPA-H slab with a transverse section of 145 mm×1600 mm was 41.8 mm,with corresponding reduction amounts for Segment 0 to Segment 4 of 15.8,7.3,6.5,6.4,and 5.8 mm,respectively.
基金supported by the National Natural Science Foundation of China(12072136).
文摘Research on the mechanical–electrical properties is crucial for designing and preparing high-temperature superconducting(HTS)cables.Various winding core structures can influence the mechanical–electrical behavior of cables,but the impact of alterations in the winding core structure on the mechanical–electrical behavior of superconducting cables remains unclear.This paper presents a 3D finite element model to predict the performance of three cables with different core structures when subjected to transverse compression and axial tension.The three cables analyzed are CORC(conductor-on-round-core),CORT(conductor-on-round-tube),and HFRC(conductor-on-spiral-tube).A parametric analysis is carried out by varying the core diameter and inner-to-outer diameter ratio.Results indicate that the CORT cable demonstrates better performance in transverse compression compared to the CORC cable,aligning with experimental data.Among the three cables,the HFRC cables exhibit the weakest resistance to transverse deformation.However,the HFRC cable demonstrates superior tensile deformation resistance compared to the CORT cable,provided that the transverse compression properties are maintained.Finite element results also show that the optimum inner-to-outer diameter ratios for achieving the best transverse compression performance are approximately 0.8 for CORT cables and 0.6 for HFRC cables.Meanwhile,the study explores the effect of structural changes in HTS cable winding cores on their electromagnetic properties.It recommends utilizing small tape gaps,lower frequencies,and spiral core construction to minimize eddy losses.The findings presented in this paper offer valuable insights for the commercialization and practical manufacturing of HTS cables.
文摘For the first time,the linear and nonlinear vibrations of composite rectangular sandwich plates with various geometric patterns of lattice core have been analytically examined in this work.The plate comprises a lattice core located in the middle and several homogeneous orthotropic layers that are symmetrical relative to it.For this purpose,the partial differential equations of motion have been derived based on the first-order shear deformation theory,employing Hamilton’s principle and Von Kármán’s nonlinear displacement-strain relations.Then,the nonlinear partial differential equations of the plate are converted into a time-dependent nonlinear ordinary differential equation(Duffing equation)by applying the Galerkin method.From the solution of this equation,the natural frequencies are extracted.Then,to calculate the non-linear frequencies of the plate,the non-linear equation of the plate has been solved analytically using the method of multiple scales.Finally,the effect of some critical parameters of the system,such as the thickness,height,and different angles of the stiffeners on the linear and nonlinear frequencies,has been analyzed in detail.To confirmthe solution method,the results of this research have been compared with the reported results in the literature and finite elements in ABAQUS,and a perfect match is observed.The results reveal that the geometry and configuration of core ribs strongly affect the natural frequencies of the plate.
文摘在现有的工业系统中,利用无监督算法进行工业场景的结构异常检测是一种非常重要的手段。针对现有无监督异常检测模型对离群正常特征的低敏特性,提出一种基于PatchCore改进的无监督异常检测模型。首先,引入无监督聚类算法对其核心特征集进行聚类采样,以降低算法对离群的正常特征的敏感度。其次,以余弦相似度作为度量标准,仅考虑特征向量方向的相似性,从而消除正常特征向量内异常值导致欧式距离异常的影响。最后,在MVTec LOCO AD和MVTec AD数据集上分别进行验证。实验结果表明,改进的PatchCore模型在MVTec LOCO AD和MVTec AD数据集上的图像级AUROC和像素级AUROC得分分别达到0.876和0.860,与PatchCore模型相比,分别提升了5.1%和3.7%。
基金National Key Research and Development Program of China (No.2021YFC3100800)the National Natural Science Foundation of China (Nos.42407235 and 42271026)+1 种基金the Project of Sanya Yazhou Bay Science and Technology City (No.SCKJ-JYRC-2023-54)supported by the Hefei advanced computing center
文摘Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing,digital core technology,and theoretical modelling.Two CRL types with contrasting mesostructures were characterized across three scales.Macroscopically,CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa,respectively.Mesoscopically,CRL-I featured small-scale highly interconnected pores,whilst CRL-II developed larger stratified pores with diminished connectivity.Microscopically,both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties.A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes,revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II.Furthermore,a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior.These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.
文摘Core power is a key parameter of nuclear reactor.Traditionally,the proportional-integralderivative(PID)controllers are used to control the core power.Fractional-order PID(FOPID)controller represents the cutting edge in core power control research.In comparing with the integer-order models,fractional-order models describe the variation of core power more accurately,thus provide a comprehensive and realistic depiction for the power and state changes of reactor core.However,current fractional-order controllers cannot adjust their parameters dynamically to response the environmental changes or demands.In this paper,we aim at the stable control and dynamic responsiveness of core power.Based on the strong selflearning ability of artificial neural network(ANN),we propose a composite controller combining the ANN and FOPID controller.The FOPID controller is firstly designed and a back propagation neural network(BPNN)is then utilized to optimize the parameters of FOPID.It is shown by simulation that the composite controller enables the real-time parameter tuning via ANN and retains the advantage of FOPID controller.
