Protoporphyrin Ⅸ(PPⅨ), a basic porphyrin system found in nature, all “porphyrin-type”tetrapyrroles with a biological function are biosynthetically derived thereof. PPⅨ is a metalloprosthetic group of numerous pro...Protoporphyrin Ⅸ(PPⅨ), a basic porphyrin system found in nature, all “porphyrin-type”tetrapyrroles with a biological function are biosynthetically derived thereof. PPⅨ is a metalloprosthetic group of numerous proteins involved in diverse metabolic and respiratory processes across all domains of life, and is thus considered essential for respiring organisms. Determining the biotic and abiotic factors that influence marine microbial growth and community structure is critical for understanding global biogeochemical cycles. Here,we present vertical profiles of intracellular PPⅨ and four derivative products(Chlorophylla/b and Pheophytin-a/b) from two coastal sediment cores, alongside ancillary geochemical and 16S rRNA microbial community data. Our findings indicated that PPⅨ is present in the natural sediment environment and displays a decreasing trend with depth, revealing a significant positive correlation with both organic matter and microbial abundance. Cooccurrence networks revealed that the environmental distribution of PPⅨ was positively correlated with the microbial porphyrin producer(high genetic completeness), but negatively correlated with auxotrophs(absence or low genetic completeness). It emphasized the critical role of PPⅨ as a biological molecule involved in key physiological processes. These results suggest that PPⅨ is a prominent component of the shared extracellular metabolite pool, especially in anoxic marine sediments where it exists at physiologically relevant concentrations for microbial metabolism. This study highlighted the significance of PPⅨ in microbial ecology and its potential impact on biogeochemical cycles in marine sedimentary environments.展开更多
China’s lakes are plagued by cadmium(Cd)pollution.Dissolved organic matter(DOM)significantly regulates Cd(II)transport properties at the sediment-water interface.Understanding the effects of different DOM components ...China’s lakes are plagued by cadmium(Cd)pollution.Dissolved organic matter(DOM)significantly regulates Cd(II)transport properties at the sediment-water interface.Understanding the effects of different DOM components on the transportation properties of Cd(II)at the sediment-water interface is essential.In this study,typical DOM from different sources was selected to study Cd(II)mobility at the sediment-water interface.Results showed that terrestrial-derived DOM(fulvic acids,FA)and autochthonous-derived DOM(α-amylase,B1)inhibit Cd(II)sequestration by sediments(42.5%and 5.8%,respectively),while anthropogenic-derived DOM(sodium dodecyl benzene sulfonate,SDBS)increased the Cd(II)adsorption capacity by sediments by 2.8%.Fluorescence quenching coupling with parallel factor analysis(EEM-PARAFAC)was used to characterize different DOM components.The results showed that FA contains three kinds of components(C1,C3:protein-like components,C2:humic-like components);SDBS contains two kinds of components(C1,C2:protein-like components);B1 contains three kinds of components(C1,C2:protein-like components,C3:humic-like components).Three complex reaction modelswere used to characterize the ability of Cd(II)complex with DOM,and it was found that the humic-like component could hardly be complex with Cd(II).Accordingly,humic-like components compete for Cd(II)adsorption sites on the sediment surface and inhibit Cd(II)adsorption fromsediments.Fourier transform infrared spectroscopy(FTIR)of the sediment surface before and after Cd(II)addition was analyzed and proved the competitive adsorption theory.This study provides a better understanding of the Cd(II)mobilization behavior at the sediment-water interface and indicates that the input of humic-like DOM will increase the bioavailability of Cd.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
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
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
Fine-grained sediments are widely distributed and constitute the most abundant component in sedi-mentary systems,thus the research on their genesis and distribution is of great significance.In recent years,fine-graine...Fine-grained sediments are widely distributed and constitute the most abundant component in sedi-mentary systems,thus the research on their genesis and distribution is of great significance.In recent years,fine-grained sediment gravity-flows(FGSGF)have been recognized as an important transportation and depositional mechanism for accumulating thick successions of fine-grained sediments.Through a comprehensive review and synthesis of global research on FGSGF deposition,the characteristics,depositional mechanisms,and distribution patterns of fine-grained sediment gravity-flow deposits(FGSGFD)are discussed,and future research prospects are clarified.In addition to the traditionally recognized low-density turbidity current and muddy debris flow,wave-enhanced gravity flow,low-density muddy hyperpycnal flow,and hypopycnal plumes can all form widely distributed FGSGFD.At the same time,the evolution of FGSGF during transportation can result in transitional and hybrid gravity-flow deposits.The combination of multiple triggering mechanisms promotes the widespread develop-ment of FGSGFD,without temporal and spatial limitations.Different types and concentrations of clay minerals,organic matters,and organo-clay complexes are the keys to controlling the flow transformation of FGSGF from low-concentration turbidity currents to high-concentration muddy debris flows.Further study is needed on the interaction mechanism of FGSGF caused by different initiations,the evolution of FGSGF with the effect of organic-inorganic synergy,and the controlling factors of the distribution pat-terns of FGSGFD.The study of FGSGFD can shed some new light on the formation of widely developed thin-bedded siltstones within shales.At the same time,these insights may broaden the exploration scope of shale oil and gas,which have important geological significances for unconventional shale oil and gas.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
Sediment particles,as one of the key components of drip irrigation technology,significantly affect the service life of emitters and restrict the popularization of drip irrigation technology.Hence,two types of patch dr...Sediment particles,as one of the key components of drip irrigation technology,significantly affect the service life of emitters and restrict the popularization of drip irrigation technology.Hence,two types of patch drip irrigation emitters,focusing on the anti-clogging performance through the experiment,were investigated.The dynamic variations in the clogging characteristics of emitters,specifically were subjected to statistical analysis.The movement mechanism of emitter clogging and discharging sediment was studied.The effects of emitter structure and position factors on emitter clogging were analyzed.The results show that the pressure-compensated emitter exhibits superior anti-clogging perfor-mance,with a service life that is 227.8%greater than that of the labyrinth channel emitter.A single structural factor cannot completely evaluate the anti-clogging performance of emitters.All factors causing emitter clogging should be considered comprehensively.Emitters contain sensitive sediment prone to clogging,however,significant blockage occurs primarily when the sediment content is elevated.The discharge of sediment,denoted as V90,from the emitter is affected by the accumulative effect of clogged sediment.These results may offer valuable insights for the application and advancement of drip irrigation technology.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
This study evaluates the dynamics of trace metals impacts on the ecosystems of the Bartlett Pond, a small shallow wetland pond located in Laredo, Texas by analyzing sediment samples taken from four quadrants of the po...This study evaluates the dynamics of trace metals impacts on the ecosystems of the Bartlett Pond, a small shallow wetland pond located in Laredo, Texas by analyzing sediment samples taken from four quadrants of the pond. The concentrations of trace elements in sediment samples are highest for iron (Fe), followed by chromium (Cr), then lead (Pb), with lower concentration of antimony (Sb), cobalt (Co), arsenic (As), cadmium (Cd), and the lowest concentration being thallium (Tl) within Bartlett Pond. The sediment quality of the pond is acceptable for organisms and the environment as trace element concentrations (e.g. As, Cd, Cr, and Pb) are within the probable effect concentration (PEC) of National Ocean and Atmospheric Administration (NOAA) guidelines although the PEC values for Co, Fe, Sb and Tl are not given. Bivariate and multivariate correlation analysis shows that most trace elements exhibit a strong positive correlation among them indicating the same anthropogenic sources and biogeochemical processes control these trace elements concentrations within the pond. We provided a comprehensive snapshot of trace element concentrations in sediments through descriptive analysis, laying the foundation for future environmental risk assessments. Correlation analysis of eight trace elements helped identify relationships, offering insights into pollution sources and potential health impacts. Additionally, univariate and multivariate predictive analyses generated numerous models, extending beyond the interpretation of partial and full regression coefficients. We also included graphical analyses of trace element variations, which are critical for understanding environmental processes and geochemical patterns. These findings advance our understanding about trace metals dynamics in sediments and may be a valuable reference for ecosystems and environmental management of different landscapes.展开更多
Under the background of global climate change, anthropogenic processes have profoundly altered the sources and transport mechanisms of coastal sediments. While previous research has primarily focused on large river de...Under the background of global climate change, anthropogenic processes have profoundly altered the sources and transport mechanisms of coastal sediments. While previous research has primarily focused on large river delta coasts,the responses of the widely distributed small bays dominated by ocean dynamics, has received comparatively less attention. To address this gap, this study examines the Weihai Bay, located in the northeast of Shandong Peninsula,China. By integrating total organic carbon isotope tracers(δ~(13)C and C/N) with sediment transport modeling, we systematically analyze the spatiotemporal patterns of surface sediment grain size inside and outside the bay, along with their responses to natural and human-induced drivers. Our findings reveal that the sedimentary environment of Weihai Bay is governed by the combined effects of tidal currents, ocean currents, wave activity, and sediment supply. Tidal dynamics dominate the hydrodynamic conditions within the bay, while ocean currents predominate offshore. Surface sediments in the bay are primarily composed of silt, originating from sediments carried by the Yellow Sea Warm Current. These sediments enter the bay through the southern bay mouth under tidal forcing, are redistributed counterclockwise by residual tidal currents, and eventually exit via the northern bay mouth. Coarser sediments in specific areas are primarily controlled by strong wave action and terrestrial inputs. Between 1988 and 2023, Weihai Bay sediments have undergone a noticeable coarsening trend, primarily driven by anthropogenic modifications to sediment supply and hydrodynamic regimes. Coastal reclamation, shoreline modification, and infrastructure development have intensified coarse-grained terrestrial sediment input. Concurrently, shoreline advancement has reduced wave dissipation, enhancing nearshore hydrodynamics and accelerating sediment coarsening. This study highlights the sensitivity of small bay sedimentary environments to anthropogenic forcing, advancing our understanding of the coupled human-marine sediment system and providing a scientific basis for coastal sediment evolution under the dual influences of climate change and human activity.展开更多
Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly im...Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly improved optoelectronic performance.In this work,we studied the effect of introducing halogen precursors on the structure of classical PbS nanocrystals(NCs)during the synthesis process and realized the preparation of PbS/Pb_(3)S_(2)X_(2) core/shell structure for the first time.The core/shell structure can effectively improve their optical properties.Furthermore,our approach enables the synthesis of Pb_(3)S_(2)Br_(2) that had not yet been reported.Our results not only provide valuable insights into the heterogeneous integration of PbYX and PbY materials to elevate material properties but also provide an effective method for further expanding the preparation of PbYX material systems.展开更多
Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,a...Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,and reservoir characteristics of shale oil of fine-grained sediment deposition in continental freshwater lacustrine basins,with a focus on the Chang 7_(3) sub-member of Triassic Yanchang Formation.The research integrates a variety of exploration data,including field outcrops,drilling,logging,core samples,geochemical analyses,and flume simulation.The study indicates that:(1)The paleoenvironment of the Chang 7_(3) deposition is characterized by a warm and humid climate,frequent monsoon events,and a large water depth of freshwater lacustrine basin.The paleogeomorphology exhibits an asymmetrical pattern,with steep slopes in the southwest and gentle slopes in the northeast,which can be subdivided into microgeomorphological units,including depressions and ridges in lakebed,as well as ancient channels.(2)The Chang 7_(3) sub-member is characterized by a diverse array of fine-grained sediments,including very fine sandstone,siltstone,mudstone and tuff.These sediments are primarily distributed in thin interbedded and laminated arrangements vertically.The overall grain size of the sandstone predominantly falls below 62.5μm,with individual layer thicknesses of 0.05–0.64 m.The deposits contain intact plant fragments and display various sedimentary structure,such as wavy bedding,inverse-to-normal grading sequence,and climbing ripple bedding,which indicating a depositional origin associated with density flows.(3)Flume simulation experiments have successfully replicated the transport processes and sedimentary characteristics associated with density flows.The initial phase is characterized by a density-velocity differential,resulting in a thicker,coarser sediment layer at the flow front,while the upper layers are thinner and finer in grain size.During the mid-phase,sliding water effects cause the fluid front to rise and facilitate rapid forward transport.This process generates multiple“new fronts”,enabling the long-distance transport of fine-grained sandstones,such as siltstone and argillaceous siltstone,into the center of the lake basin.(4)A sedimentary model primarily controlled by hyperpynal flows was established for the southwestern part of the basin,highlighting that the frequent occurrence of flood events and the steep slope topography in this area are primary controlling factors for the development of hyperpynal flows.(5)Sandstone and mudstone in the Chang 7_(3) sub-member exhibit micro-and nano-scale pore-throat systems,shale oil is present in various lithologies,while the content of movable oil varies considerably,with sandstone exhibiting the highest content of movable oil.(6)The fine-grained sediment complexes formed by multiple episodes of sandstones and mudstones associated with density flow in the Chang 7_(3) formation exhibit characteristics of“overall oil-bearing with differential storage capacity”.The combination of mudstone with low total organic carbon content(TOC)and siltstone is identified as the most favorable exploration target at present.展开更多
The pore structures of the Majiagou Formation in the Ordos Basin are complex,featuring micro-and nano-scale intra-crystalline and inter-crystalline pores that significantly impact hydrocarbon storage and flow.Precisel...The pore structures of the Majiagou Formation in the Ordos Basin are complex,featuring micro-and nano-scale intra-crystalline and inter-crystalline pores that significantly impact hydrocarbon storage and flow.Precisely characterizing the rock internal structures is crucial for reservoir exploration and development.However,it is difficult to accurately characterize the pore structure of rock using traditional imaging methods to meet the simulation requirements.In this context,this study focuses on high-resolution 3D digital core reconstruction using the SliceGAN model.Specifically,the Modular Automated Processing System(MAPS)image and Quanti-tative Evaluation of Minerals by Scanning Electron Microscopy(QEMSCAN)image were combined to divide MAPS into three categories:pore,dolomite,and calcite.Then,through the SliceGAN algorithm,the 3D digital core was reconstructed.To evaluate the reconstruction,the auto-correlation function,two-point probability function,porosity,mineral content,and specific surface area were employed.The results show that the SliceGAN can effectively capture the micro-features in the core,and the internal structure of the generated core was consistent with that of the original core.This study provided a new sight for reconstructing cores with complex pore structures and strong heterogeneity and innovatively supports tight carbonate reservoir characterization and evaluation.展开更多
Organic phosphorus(OP)constitutes an important fraction of total phosphorus in lake sediments,with its mobility being influenced by mineralization and transformation of organic carbon(OC).OP and OC co-exist in various...Organic phosphorus(OP)constitutes an important fraction of total phosphorus in lake sediments,with its mobility being influenced by mineralization and transformation of organic carbon(OC).OP and OC co-exist in various forms in the environment,thus a thorough investigation on the impact of OC fractions on the release of OP in sediments should be comprehensively carried out.This study determined the chemical forms of OP and OC in the sediments over four seasons in Lake Taihu and found temporal and spatial variations in their concentrations.The concentration of total OP and total OC ranged from 133 to 348 mg/kg and 4.77 to 21.19 mg/kg,respectively.Correlation between chemical fractions of OP and OC also revealed that Na OH-extracted OP,and fulvic acid-bound and humic acid-bound OP were positively correlated with humic-OC and hot hydrolysis-OC.These results suggest that the algal-derived OC degradation and mineralization may enhance OP mineralization,converting stable or moderately active OP into active forms or inorganic phosphorus under cyanobacterial bloom.This study provides insight and guiding support for investigating the impact of organic matter components on the transformation of OP after cyanobacterial degradation in eutrophic lakes.展开更多
BACKGROUND Pain in the back or pelvis or fear of back pain may affect the timing or cocontraction of the core muscles.In both static and dynamic movements,the Sahrmann core stability test provides an assessment of cor...BACKGROUND Pain in the back or pelvis or fear of back pain may affect the timing or cocontraction of the core muscles.In both static and dynamic movements,the Sahrmann core stability test provides an assessment of core muscle activation and a person's ability to stabilize the lumbopelvic complex.Preparatory cues and images can be used to increase the activation of these muscles.To attain optimal movement patterns,it will be necessary to determine what cueing will give the most effective results for core stability.AIM To investigate the effects of external and internal cues on core muscle activation during the Sahrmann five-level core stability test.METHODS Total 68 participants(21.83±3.47 years)were randomly allocated to an external(n=35)or internal cue group(n=33).Participants performed the Sahrmann fivelevel core stability test without a cue as baseline and the five-level stability exercises with an internal or external cue.External cue group received a pressure biofeedback unit(PBU),and the internal cue group received an audio cue.A Delsys Trigno^(TM)surface electromyography unit was used for muscle activation from the rectus abdominis,external oblique,and transverse abdominis/internal oblique muscles.RESULTS Linear mixed effects model analysis showed that cueing had a significant effect on core muscle activation(P=0.001);however,there was no significant difference between cue types(internal or external)(P=0.130).CONCLUSION Both external and internal cueing have significant effects on core muscle activation during the Sahrmann five-level core stability test and the PBU does not create higher muscle activation than internal cueing.展开更多
基金supported by the Doctoral Research Initiation Fund Project of Hebei Normal University(No.L2025B19)PhD Fellowship of the State Key Laboratory of Marine Environmental Science at Xiamen University.
文摘Protoporphyrin Ⅸ(PPⅨ), a basic porphyrin system found in nature, all “porphyrin-type”tetrapyrroles with a biological function are biosynthetically derived thereof. PPⅨ is a metalloprosthetic group of numerous proteins involved in diverse metabolic and respiratory processes across all domains of life, and is thus considered essential for respiring organisms. Determining the biotic and abiotic factors that influence marine microbial growth and community structure is critical for understanding global biogeochemical cycles. Here,we present vertical profiles of intracellular PPⅨ and four derivative products(Chlorophylla/b and Pheophytin-a/b) from two coastal sediment cores, alongside ancillary geochemical and 16S rRNA microbial community data. Our findings indicated that PPⅨ is present in the natural sediment environment and displays a decreasing trend with depth, revealing a significant positive correlation with both organic matter and microbial abundance. Cooccurrence networks revealed that the environmental distribution of PPⅨ was positively correlated with the microbial porphyrin producer(high genetic completeness), but negatively correlated with auxotrophs(absence or low genetic completeness). It emphasized the critical role of PPⅨ as a biological molecule involved in key physiological processes. These results suggest that PPⅨ is a prominent component of the shared extracellular metabolite pool, especially in anoxic marine sediments where it exists at physiologically relevant concentrations for microbial metabolism. This study highlighted the significance of PPⅨ in microbial ecology and its potential impact on biogeochemical cycles in marine sedimentary environments.
基金supported by the National Natural Science Foundation of China(Nos.42307524,and 51879103).
文摘China’s lakes are plagued by cadmium(Cd)pollution.Dissolved organic matter(DOM)significantly regulates Cd(II)transport properties at the sediment-water interface.Understanding the effects of different DOM components on the transportation properties of Cd(II)at the sediment-water interface is essential.In this study,typical DOM from different sources was selected to study Cd(II)mobility at the sediment-water interface.Results showed that terrestrial-derived DOM(fulvic acids,FA)and autochthonous-derived DOM(α-amylase,B1)inhibit Cd(II)sequestration by sediments(42.5%and 5.8%,respectively),while anthropogenic-derived DOM(sodium dodecyl benzene sulfonate,SDBS)increased the Cd(II)adsorption capacity by sediments by 2.8%.Fluorescence quenching coupling with parallel factor analysis(EEM-PARAFAC)was used to characterize different DOM components.The results showed that FA contains three kinds of components(C1,C3:protein-like components,C2:humic-like components);SDBS contains two kinds of components(C1,C2:protein-like components);B1 contains three kinds of components(C1,C2:protein-like components,C3:humic-like components).Three complex reaction modelswere used to characterize the ability of Cd(II)complex with DOM,and it was found that the humic-like component could hardly be complex with Cd(II).Accordingly,humic-like components compete for Cd(II)adsorption sites on the sediment surface and inhibit Cd(II)adsorption fromsediments.Fourier transform infrared spectroscopy(FTIR)of the sediment surface before and after Cd(II)addition was analyzed and proved the competitive adsorption theory.This study provides a better understanding of the Cd(II)mobilization behavior at the sediment-water interface and indicates that the input of humic-like DOM will increase the bioavailability of Cd.
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(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.
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 National Natural Science Foundation of China(Grant Nos.42072126,42372139)the Natural Science Foundation of Sichuan Province(Grant Nos.2022NSFSC0990).
文摘Fine-grained sediments are widely distributed and constitute the most abundant component in sedi-mentary systems,thus the research on their genesis and distribution is of great significance.In recent years,fine-grained sediment gravity-flows(FGSGF)have been recognized as an important transportation and depositional mechanism for accumulating thick successions of fine-grained sediments.Through a comprehensive review and synthesis of global research on FGSGF deposition,the characteristics,depositional mechanisms,and distribution patterns of fine-grained sediment gravity-flow deposits(FGSGFD)are discussed,and future research prospects are clarified.In addition to the traditionally recognized low-density turbidity current and muddy debris flow,wave-enhanced gravity flow,low-density muddy hyperpycnal flow,and hypopycnal plumes can all form widely distributed FGSGFD.At the same time,the evolution of FGSGF during transportation can result in transitional and hybrid gravity-flow deposits.The combination of multiple triggering mechanisms promotes the widespread develop-ment of FGSGFD,without temporal and spatial limitations.Different types and concentrations of clay minerals,organic matters,and organo-clay complexes are the keys to controlling the flow transformation of FGSGF from low-concentration turbidity currents to high-concentration muddy debris flows.Further study is needed on the interaction mechanism of FGSGF caused by different initiations,the evolution of FGSGF with the effect of organic-inorganic synergy,and the controlling factors of the distribution pat-terns of FGSGFD.The study of FGSGFD can shed some new light on the formation of widely developed thin-bedded siltstones within shales.At the same time,these insights may broaden the exploration scope of shale oil and gas,which have important geological significances for unconventional shale oil and gas.
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.
基金National Natural Science Foundation of China(52269011,52469008)。
文摘Sediment particles,as one of the key components of drip irrigation technology,significantly affect the service life of emitters and restrict the popularization of drip irrigation technology.Hence,two types of patch drip irrigation emitters,focusing on the anti-clogging performance through the experiment,were investigated.The dynamic variations in the clogging characteristics of emitters,specifically were subjected to statistical analysis.The movement mechanism of emitter clogging and discharging sediment was studied.The effects of emitter structure and position factors on emitter clogging were analyzed.The results show that the pressure-compensated emitter exhibits superior anti-clogging perfor-mance,with a service life that is 227.8%greater than that of the labyrinth channel emitter.A single structural factor cannot completely evaluate the anti-clogging performance of emitters.All factors causing emitter clogging should be considered comprehensively.Emitters contain sensitive sediment prone to clogging,however,significant blockage occurs primarily when the sediment content is elevated.The discharge of sediment,denoted as V90,from the emitter is affected by the accumulative effect of clogged sediment.These results may offer valuable insights for the application and advancement of drip irrigation technology.
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.
文摘This study evaluates the dynamics of trace metals impacts on the ecosystems of the Bartlett Pond, a small shallow wetland pond located in Laredo, Texas by analyzing sediment samples taken from four quadrants of the pond. The concentrations of trace elements in sediment samples are highest for iron (Fe), followed by chromium (Cr), then lead (Pb), with lower concentration of antimony (Sb), cobalt (Co), arsenic (As), cadmium (Cd), and the lowest concentration being thallium (Tl) within Bartlett Pond. The sediment quality of the pond is acceptable for organisms and the environment as trace element concentrations (e.g. As, Cd, Cr, and Pb) are within the probable effect concentration (PEC) of National Ocean and Atmospheric Administration (NOAA) guidelines although the PEC values for Co, Fe, Sb and Tl are not given. Bivariate and multivariate correlation analysis shows that most trace elements exhibit a strong positive correlation among them indicating the same anthropogenic sources and biogeochemical processes control these trace elements concentrations within the pond. We provided a comprehensive snapshot of trace element concentrations in sediments through descriptive analysis, laying the foundation for future environmental risk assessments. Correlation analysis of eight trace elements helped identify relationships, offering insights into pollution sources and potential health impacts. Additionally, univariate and multivariate predictive analyses generated numerous models, extending beyond the interpretation of partial and full regression coefficients. We also included graphical analyses of trace element variations, which are critical for understanding environmental processes and geochemical patterns. These findings advance our understanding about trace metals dynamics in sediments and may be a valuable reference for ecosystems and environmental management of different landscapes.
基金The Fund of National Archaeological Talent Promotion Program of China under contract No.2024-269“2024 Shandong Weihai Underwater Archaeological Survey” program by National Center for Archaeology under contract No. 20243160A0965+2 种基金Fujian Provincial Science and Technology Planning Projects under contract No. 2022L3001Provincial Natural Science Foundation of Fujian under contract No. 2023J01020MEL Internal Program of Xiamen University under contract No. MELRI2303。
文摘Under the background of global climate change, anthropogenic processes have profoundly altered the sources and transport mechanisms of coastal sediments. While previous research has primarily focused on large river delta coasts,the responses of the widely distributed small bays dominated by ocean dynamics, has received comparatively less attention. To address this gap, this study examines the Weihai Bay, located in the northeast of Shandong Peninsula,China. By integrating total organic carbon isotope tracers(δ~(13)C and C/N) with sediment transport modeling, we systematically analyze the spatiotemporal patterns of surface sediment grain size inside and outside the bay, along with their responses to natural and human-induced drivers. Our findings reveal that the sedimentary environment of Weihai Bay is governed by the combined effects of tidal currents, ocean currents, wave activity, and sediment supply. Tidal dynamics dominate the hydrodynamic conditions within the bay, while ocean currents predominate offshore. Surface sediments in the bay are primarily composed of silt, originating from sediments carried by the Yellow Sea Warm Current. These sediments enter the bay through the southern bay mouth under tidal forcing, are redistributed counterclockwise by residual tidal currents, and eventually exit via the northern bay mouth. Coarser sediments in specific areas are primarily controlled by strong wave action and terrestrial inputs. Between 1988 and 2023, Weihai Bay sediments have undergone a noticeable coarsening trend, primarily driven by anthropogenic modifications to sediment supply and hydrodynamic regimes. Coastal reclamation, shoreline modification, and infrastructure development have intensified coarse-grained terrestrial sediment input. Concurrently, shoreline advancement has reduced wave dissipation, enhancing nearshore hydrodynamics and accelerating sediment coarsening. This study highlights the sensitivity of small bay sedimentary environments to anthropogenic forcing, advancing our understanding of the coupled human-marine sediment system and providing a scientific basis for coastal sediment evolution under the dual influences of climate change and human activity.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0110300)the National Natural Science Foundation of China(Grant Nos.52372215,92163114,and 52202274)+5 种基金the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20230504)the Special Fund for the"Dual Carbon"Science and Technology Innovation of Jiangsu province(Industrial Prospect and Key Technology Research program)(Grant Nos.BE2022023 and BE2022021)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant No.21KJA430004)Gusu Innovation and Entre preneurship Leading Talent Program(Grant No.ZXL2022451)the China Postdoctoral Science Foundation(Grant No.2023M732523)supported by Suzhou Key Laboratory of Functional Nano&Soft Materials,Collaborative Innovation Center of Suzhou Nano Science&Technology,the 111 Project.
文摘Lead chalcohalides(PbYX,X=Cl,Br,I;Y=S,Se)is an extension of the classic Pb chalcogenides(PbY).Constructing the heterogeneous integration with PbYX and PbY material systems makes it possible to achieve significantly improved optoelectronic performance.In this work,we studied the effect of introducing halogen precursors on the structure of classical PbS nanocrystals(NCs)during the synthesis process and realized the preparation of PbS/Pb_(3)S_(2)X_(2) core/shell structure for the first time.The core/shell structure can effectively improve their optical properties.Furthermore,our approach enables the synthesis of Pb_(3)S_(2)Br_(2) that had not yet been reported.Our results not only provide valuable insights into the heterogeneous integration of PbYX and PbY materials to elevate material properties but also provide an effective method for further expanding the preparation of PbYX material systems.
基金Supported by the CNPC Major Science and Technology Project(2021DJ1806).
文摘Based on recent advancements in shale oil exploration within the Ordos Basin,this study presents a comprehensive investigation of the paleoenvironment,lithofacies assemblages and distribution,depositional mechanisms,and reservoir characteristics of shale oil of fine-grained sediment deposition in continental freshwater lacustrine basins,with a focus on the Chang 7_(3) sub-member of Triassic Yanchang Formation.The research integrates a variety of exploration data,including field outcrops,drilling,logging,core samples,geochemical analyses,and flume simulation.The study indicates that:(1)The paleoenvironment of the Chang 7_(3) deposition is characterized by a warm and humid climate,frequent monsoon events,and a large water depth of freshwater lacustrine basin.The paleogeomorphology exhibits an asymmetrical pattern,with steep slopes in the southwest and gentle slopes in the northeast,which can be subdivided into microgeomorphological units,including depressions and ridges in lakebed,as well as ancient channels.(2)The Chang 7_(3) sub-member is characterized by a diverse array of fine-grained sediments,including very fine sandstone,siltstone,mudstone and tuff.These sediments are primarily distributed in thin interbedded and laminated arrangements vertically.The overall grain size of the sandstone predominantly falls below 62.5μm,with individual layer thicknesses of 0.05–0.64 m.The deposits contain intact plant fragments and display various sedimentary structure,such as wavy bedding,inverse-to-normal grading sequence,and climbing ripple bedding,which indicating a depositional origin associated with density flows.(3)Flume simulation experiments have successfully replicated the transport processes and sedimentary characteristics associated with density flows.The initial phase is characterized by a density-velocity differential,resulting in a thicker,coarser sediment layer at the flow front,while the upper layers are thinner and finer in grain size.During the mid-phase,sliding water effects cause the fluid front to rise and facilitate rapid forward transport.This process generates multiple“new fronts”,enabling the long-distance transport of fine-grained sandstones,such as siltstone and argillaceous siltstone,into the center of the lake basin.(4)A sedimentary model primarily controlled by hyperpynal flows was established for the southwestern part of the basin,highlighting that the frequent occurrence of flood events and the steep slope topography in this area are primary controlling factors for the development of hyperpynal flows.(5)Sandstone and mudstone in the Chang 7_(3) sub-member exhibit micro-and nano-scale pore-throat systems,shale oil is present in various lithologies,while the content of movable oil varies considerably,with sandstone exhibiting the highest content of movable oil.(6)The fine-grained sediment complexes formed by multiple episodes of sandstones and mudstones associated with density flow in the Chang 7_(3) formation exhibit characteristics of“overall oil-bearing with differential storage capacity”.The combination of mudstone with low total organic carbon content(TOC)and siltstone is identified as the most favorable exploration target at present.
基金financially supported by the open fund of Key Lab-oratory of Exploration Technologies for Oil and Gas Resources(Yangtze University),Ministry of Education,NO PI2023-03the open foundation of the National Engineering Laboratory for Exploration and Develop-ment of Low-Permeability Oil&Gas Fields and the National Natural Science Foundation of China(No.42474159).
文摘The pore structures of the Majiagou Formation in the Ordos Basin are complex,featuring micro-and nano-scale intra-crystalline and inter-crystalline pores that significantly impact hydrocarbon storage and flow.Precisely characterizing the rock internal structures is crucial for reservoir exploration and development.However,it is difficult to accurately characterize the pore structure of rock using traditional imaging methods to meet the simulation requirements.In this context,this study focuses on high-resolution 3D digital core reconstruction using the SliceGAN model.Specifically,the Modular Automated Processing System(MAPS)image and Quanti-tative Evaluation of Minerals by Scanning Electron Microscopy(QEMSCAN)image were combined to divide MAPS into three categories:pore,dolomite,and calcite.Then,through the SliceGAN algorithm,the 3D digital core was reconstructed.To evaluate the reconstruction,the auto-correlation function,two-point probability function,porosity,mineral content,and specific surface area were employed.The results show that the SliceGAN can effectively capture the micro-features in the core,and the internal structure of the generated core was consistent with that of the original core.This study provided a new sight for reconstructing cores with complex pore structures and strong heterogeneity and innovatively supports tight carbonate reservoir characterization and evaluation.
基金supported by the Project of Ecological and Environmental Protection Integration Research Institute in Yangtze River Delta(No.ZX2023SZY118)the Special Basic Research Service for the Central Level Public Welfare Research Institute(No.GYZX230409)+1 种基金the National Natural Science Foundation of China(No.42407557)the Belt and Road Special Foundation of the National Key Laboratory of Water Disaster Prevention,China(No.2023491611)。
文摘Organic phosphorus(OP)constitutes an important fraction of total phosphorus in lake sediments,with its mobility being influenced by mineralization and transformation of organic carbon(OC).OP and OC co-exist in various forms in the environment,thus a thorough investigation on the impact of OC fractions on the release of OP in sediments should be comprehensively carried out.This study determined the chemical forms of OP and OC in the sediments over four seasons in Lake Taihu and found temporal and spatial variations in their concentrations.The concentration of total OP and total OC ranged from 133 to 348 mg/kg and 4.77 to 21.19 mg/kg,respectively.Correlation between chemical fractions of OP and OC also revealed that Na OH-extracted OP,and fulvic acid-bound and humic acid-bound OP were positively correlated with humic-OC and hot hydrolysis-OC.These results suggest that the algal-derived OC degradation and mineralization may enhance OP mineralization,converting stable or moderately active OP into active forms or inorganic phosphorus under cyanobacterial bloom.This study provides insight and guiding support for investigating the impact of organic matter components on the transformation of OP after cyanobacterial degradation in eutrophic lakes.
文摘BACKGROUND Pain in the back or pelvis or fear of back pain may affect the timing or cocontraction of the core muscles.In both static and dynamic movements,the Sahrmann core stability test provides an assessment of core muscle activation and a person's ability to stabilize the lumbopelvic complex.Preparatory cues and images can be used to increase the activation of these muscles.To attain optimal movement patterns,it will be necessary to determine what cueing will give the most effective results for core stability.AIM To investigate the effects of external and internal cues on core muscle activation during the Sahrmann five-level core stability test.METHODS Total 68 participants(21.83±3.47 years)were randomly allocated to an external(n=35)or internal cue group(n=33).Participants performed the Sahrmann fivelevel core stability test without a cue as baseline and the five-level stability exercises with an internal or external cue.External cue group received a pressure biofeedback unit(PBU),and the internal cue group received an audio cue.A Delsys Trigno^(TM)surface electromyography unit was used for muscle activation from the rectus abdominis,external oblique,and transverse abdominis/internal oblique muscles.RESULTS Linear mixed effects model analysis showed that cueing had a significant effect on core muscle activation(P=0.001);however,there was no significant difference between cue types(internal or external)(P=0.130).CONCLUSION Both external and internal cueing have significant effects on core muscle activation during the Sahrmann five-level core stability test and the PBU does not create higher muscle activation than internal cueing.
