The travel time of rock compressional waves is an essential parameter used for estimating important rock properties,such as porosity,permeability,and lithology.Current methods,like wireline logging tests,provide broad...The travel time of rock compressional waves is an essential parameter used for estimating important rock properties,such as porosity,permeability,and lithology.Current methods,like wireline logging tests,provide broad measurements but lack finer resolution.Laboratory-based rock core measurements offer higher resolution but are resource-intensive.Conventionally,wireline logging and rock core measurements have been used independently.This study introduces a novel approach that integrates both data sources.The method leverages the detailed features from limited core data to enhance the resolution of wireline logging data.By combining machine learning with random field theory,the method allows for probabilistic predictions in regions with sparse data sampling.In this framework,12 parameters from wireline tests are used to predict trends in rock core data.The residuals are modeled using random field theory.The outcomes are high-resolution predictions that combine both the predicted trend and the probabilistic realizations of the residual.By utilizing unconditional and conditional random field theories,this method enables unconditional and conditional simulations of the underlying high-resolution rock compressional wave travel time profile and provides uncertainty estimates.This integrated approach optimizes the use of existing core and logging data.Its applicability is confirmed in an oil project in West China.展开更多
Material composition and structural design are important factors influencing the electromagnetic wave(EMW)absorption performance of materials.To alleviate the impedance mismatch attributed to the high dielectric const...Material composition and structural design are important factors influencing the electromagnetic wave(EMW)absorption performance of materials.To alleviate the impedance mismatch attributed to the high dielectric constant of Ti_(3)C_(2)T_(x)MXene,we have successfully synthesized core‐shell structured SiO_(2)@MXene@MoS_(2)nanospheres.This architecture,comprising SiO_(2) as the core,MXene as the intermediate layer,and MoS_(2) as the outer shell,is achieved through an electrostatic self‐assembly method combined with a hydrothermal process.This complex core‐shell structure not only provides a variety of loss mechanisms that effectively dissipate electromagnetic energy but also prevents self‐aggregation of MXene and MoS_(2) nanosheets.Notably,the synergistic combination of SiO_(2) and MoS_(2) with highly conductive MXene enables the suitable dielectric constant of the composites,ensuring optimal impedance matching.Therefore,the core‐shell structured SiO_(2)@MXene@MoS_(2) nanospheres exhibit excellent EMW absorption performance,featuring a remarkable minimum reflection loss(RL_(min))of−52.11 dB(2.4 mm).It is noteworthy that these nanospheres achieve an ultra‐wide effective absorption bandwidth(EAB)of 6.72 GHz.This work provides a novel approach for designing and synthesizing high‐performance EMW absorbers characterized by“wide bandwidth and strong reflection loss.”展开更多
Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability...Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability,resulting in distorted resource assessments.The development of in situ temperaturepreserved coring(ITP-Coring)technology for deep reservoir rock is urgent,and thermal insulation materials are key.Therefore,hollow glass microsphere/epoxy resin thermal insulation materials(HGM/EP materials)were proposed as thermal insulation materials.The materials properties under coupled hightemperature and high-pressure(HTHP)conditions were tested.The results indicated that high pressures led to HGM destruction and that the materials water absorption significantly increased;additionally,increasing temperature accelerated the process.High temperatures directly caused the thermal conductivity of the materials to increase;additionally,the thermal conduction and convection of water caused by high pressures led to an exponential increase in the thermal conductivity.High temperatures weakened the matrix,and high pressures destroyed the HGM,which resulted in a decrease in the tensile mechanical properties of the materials.The materials entered the high elastic state at 150℃,and the mechanical properties were weakened more obviously,while the pressure led to a significant effect when the water absorption was above 10%.Meanwhile,the tensile strength/strain were 13.62 MPa/1.3%and 6.09 MPa/0.86%at 100℃ and 100 MPa,respectively,which meet the application requirements of the self-designed coring device.Finally,K46-f40 and K46-f50 HGM/EP materials were proven to be suitable for ITP-Coring under coupled conditions below 100℃ and 100 MPa.To further improve the materials properties,the interface layer and EP matrix should be optimized.The results can provide references for the optimization and engineering application of materials and thus technical support for deep oil and gas resource development.展开更多
Remarkable progress has characterized the field of electrocatalysis in recent decades,driven in part by an enhanced comprehension of catalyst structures and mechanisms at the nanoscale.Atomically precise metal nanoclu...Remarkable progress has characterized the field of electrocatalysis in recent decades,driven in part by an enhanced comprehension of catalyst structures and mechanisms at the nanoscale.Atomically precise metal nanoclusters,serving as exemplary models,significantly expand the range of accessible structures through diverse cores and ligands,creating an exceptional platform for the investigation of catalytic reactions.Notably,ligand‐protected Au nanoclusters(NCs)with precisely defined core numbers offer a distinct advantage in elucidating the correlation between their specific structures and the reaction mechanisms in electrocatalysis.The strategic modulation of the fine microstructures of Au NCs presents crucial opportunities for tailoring their electrocatalytic performance across various reactions.This review delves into the profound structural effects of Au NC cores and ligands in electrocatalysis,elucidating their underlying mechanisms.A detailed exploration of the fundamentals of Au NCs,considering core and ligand structures,follows.Subsequently,the interaction between the core and ligand structures of Au NCs and their impact on electrocatalytic performance in diverse reactions are examined.Concluding the discourse,challenges and personal prospects are presented to guide the rational design of efficient electrocatalysts and advance electrocatalytic reactions.展开更多
Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures,flexibility,and attractive appearance.However,the inability of controlling and regulati...Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures,flexibility,and attractive appearance.However,the inability of controlling and regulating vibrations and destroying them afterward is a challenge to scientists.In this paper,the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms.A five-layer sandwich doubly curved micro-composite shell,comprising two piezoelectric layers for the sensor and actuator,is modeled by the fourth-order shear deformation theory.The core(honeycomb,truss,and corrugated)is analyzed for the bearing of transverse shear forces.The results show that the honeycomb core has a greater effect on the vibrations.When the parameters related to the core and the weight percentage of graphene increase,the frequency increases.The uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency increases.Furthermore,without taking into account the piezoelectric layers,the third-order shear deformation theory(TSDT)and fourth-order shear deformation theory(FOSDT)align closely.However,when the piezoelectric layers are incorporated,these two theories diverge significantly,with the frequencies in the FOSDT being lower than those in the TSDT.展开更多
An innovative multi-layer composite explosion containment vessel(CECV)utilizing a sliding steel platealuminum honeycomb-fiber cloth sandwich is put forward to improve the anti-explosion capacity of a conventional sing...An innovative multi-layer composite explosion containment vessel(CECV)utilizing a sliding steel platealuminum honeycomb-fiber cloth sandwich is put forward to improve the anti-explosion capacity of a conventional single-layer explosion containment vessel(SECV).Firstly,a series of experiments and finite element(FE)simulations of internal explosions are implemented to understand the basic anti-explosion characteristics of a SECV and the rationality of the computational models and methods is verified by the comparison between the experimental results and simulation results.Based on this,the CECV is designed in detail and a variety of FE simulations are carried out to investigate effects of the sandwich structure,the explosive quantity and the laying mode of the fiber cloth on anti-explosion performance and dynamic response of the CECV under internal explosions.Simulation results indicate that the end cover is the critical position for both the SECV and CECV.The maximum pressure of the explosion shock wave and the maximum strain of the CECV can be extremely declined compared to those of the SECV.As a result,the explosive quantity the CECV can sustain is up to 20 times of that the SECV can sustain.Besides,as the explosive quantity increases,the internal pressure of the CECV keeps growing and the plastic deformation and failure of the sandwich structure become more and more severe,yielding plastic strain of the CECV in addition to elastic strain.The results also reveal that the laying angles of the fiber cloth's five layers have an impact on the anti-explosion performance of the CECV.For example,the CECV with fiber cloth layered in 0°/45°/90°/45°/0°mode has the optimal anti-capacity,compared to 0°/0°/0°/0°/0°and 0°/30°/60°/30°/0°modes.Overall,owing to remarkable anti-explosion capacity,this CECV can be regarded as a promising candidate for explosion resistance.展开更多
Phenazine-based non-fullerene acceptors(NFAs)have demonstrated great potential in improving the power conversion efficiency(PCE)of organic solar cells(OSCs).Halogenation is known to be an effective strategy for increa...Phenazine-based non-fullerene acceptors(NFAs)have demonstrated great potential in improving the power conversion efficiency(PCE)of organic solar cells(OSCs).Halogenation is known to be an effective strategy for increasing optical absorption,refining energy levels,and improving molecular packing in organic semiconductors.Herein,a series of NFAs(Pz IC-4H,Pz IC-4F,Pz IC-4Cl,Pz IC-2Br)with phenazine as the central core and with/without halogen-substituted(dicyanomethylidene)-indan-1-one(IC)as the electron-accepting end group were synthesized,and the effect of end group matched phenazine central unit on the photovoltaic performance was systematically studied.Synergetic photophysical and morphological analyses revealed that the PM6:Pz IC-4F blend involves efficient exciton dissociation,higher charge collection and transfer rates,better crystallinity,and optimal phase separation.Therefore,OSCs based on PM6:Pz IC-4F as the active layer exhibited a PCE of 16.48%with an open circuit voltage(Voc)and energy loss of 0.880 V and 0.53 e V,respectively.Accordingly,this work demonstrated a promising approach by designing phenazine-based NFAs for achieving high-performance OSCs.展开更多
A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established ...A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established by the third-order shear deformation theory(TSDT),and then combined with the fluid-structure coupling conditions,and the sound insulation is solved.The theoretical results are validated by COMSOL simulation results,and the effects of the structural parameter on the sound insulation are analyzed.Finally,the standard genetic algorithm is adopted to optimize the sound insulation of the sandwich plate.展开更多
Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic development.Thirty-three samples ...Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic development.Thirty-three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic minerals.These samples included gneisses rocks,monzogranite,and metavolcano-sedimentary rocks for both the Thalbah and Bayda groups.Using the Rf/j and Fry methods,the axial ratios(XZ)range about 2.20 to 7.10 and 1.90 to 9.10,respectively.For various rock units,the strain measurements show moderate to highly deformation.Most of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain(X).The short axes(Z)based to be subvertical foliation related with a subhorizontal foliation.The results demonstrate that contacts generated at semi-brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic units.It concluded that nappe generation in orogens results from pure shear deformation.展开更多
A new hydrothermal field(Tianshi)was discovered on the rift valley wall through plume anomaly surveys and geological work conducted in 2012 and 2018 between 2°35′N and 2°43′N of the slow-spreading Carlsber...A new hydrothermal field(Tianshi)was discovered on the rift valley wall through plume anomaly surveys and geological work conducted in 2012 and 2018 between 2°35′N and 2°43′N of the slow-spreading Carlsberg Ridge(CR).Here,the results of two expeditions conducted to detect and characterize the new hydrothermal field are reported.Mineralogical and geochemical data,as well as 14 C ages of a sediment core collected near the field are presented to reveal the hydrothermal history.Results show that the Tianshi field is a basalt-hosted hydrothermal system.Geochemical data of the sediments collected near the field indicate a strong hydrothermal contribution,and hydrothermal Fe and Cu fluxes range from 30 to 155 mg/(cm^(2)·ka)and 0.59 to 11.49 mg/(cm^(2)·ka),respectively.Temporal variations in the fluxes of hydrothermal Fe indicate that there have been at least three amplified hydrothermal venting events(H 1,H 2,and H 3)in the Tianshi field over the last 35.2 ka,in 28.6-35.2 ka BP,22.0-27.6 ka BP,and 1.2-11.4 ka BP,respectively.Hydrothermal event H 2 was driven by an increased magmatic production associated with sea level fall during the Last Glacial Maximum,while event H 3 was promoted by tectonic activity associated with a rapid sea level rise.This study further verified the role of sea level change in modulating hydrothermal activity on mid-ocean ridges.展开更多
Here,a nonhydrostatic alternative scheme(NAS)is proposed for the grey zone where the nonhydrostatic impact on the atmosphere is evident but not large enough to justify the necessity to include an implicit nonhydrostat...Here,a nonhydrostatic alternative scheme(NAS)is proposed for the grey zone where the nonhydrostatic impact on the atmosphere is evident but not large enough to justify the necessity to include an implicit nonhydrostatic solver in an atmospheric dynamical core.The NAS is designed to replace this solver,which can be incorporated into any hydrostatic models so that existing well-developed hydrostatic models can effectively serve for a longer time.Recent advances in machine learning(ML)provide a potential tool for capturing the main complicated nonlinear-nonhydrostatic relationship.In this study,an ML approach called a neural network(NN)was adopted to select leading input features and develop the NAS.The NNs were trained and evaluated with 12-day simulation results of dry baroclinic-wave tests by the Weather Research and Forecasting(WRF)model.The forward time difference of the nonhydrostatic tendency was used as the target variable,and the five selected features were the nonhydrostatic tendency at the last time step,and four hydrostatic variables at the current step including geopotential height,pressure in two different forms,and potential temperature,respectively.Finally,a practical NAS was developed with these features and trained layer by layer at a 20-km horizontal resolution,which can accurately reproduce the temporal variation and vertical distribution of the nonhydrostatic tendency.Corrected by the NN-based NAS,the improved hydrostatic solver at different horizontal resolutions can run stably for at least one month and effectively reduce most of the nonhydrostatic errors in terms of system bias,anomaly root-mean-square error,and the error of the wave spatial pattern,which proves the feasibility and superiority of this scheme.展开更多
Purpose:The collaboration relationships between innovation actors at a geographic level may be considered as grouping two separate layers,the domestic and the foreign.At the level of each layer,the relationships and t...Purpose:The collaboration relationships between innovation actors at a geographic level may be considered as grouping two separate layers,the domestic and the foreign.At the level of each layer,the relationships and the actors involved constitute a Triple Helix game.The paper distinguished three levels of analysis:the global grouping together all actors,the domestic grouping together domestic actors,and the foreign related to only actors from partner countries.Design/methodology/approach:Bibliographic records data from the Web of Science for South Korea and West Africa breakdown per innovation actors and distinguishing domestic and international collaboration are analyzed with game theory.The core,the Shapley value,and the nucleolus are computed at the three levels to measure the synergy between actors.Findings:The synergy operates more in South Korea than in West Africa;the government is more present in West Africa than in South Korea;domestic actors create more synergy in South Korea,but foreign more in West Africa;South Korea can consume all the foreign synergy,which is not the case of West Africa.Research limitations:Research data are limited to publication records;techniques and methods used may be extended to other research outputs.Practical implications:West African governments should increase their investment in science,technology,and innovation to benefit more from the synergy their innovation actors contributed at the foreign level.However,the results of the current study may not be sufficient to prove that greater investment will yield benefits from foreign synergies.Originality/value:This paper uses game theory to assess innovation systems by computing the contribution of foreign actors to knowledge production at an area level.It proposes an indicator to this end.展开更多
Geological exploration cores obtained from shale gas wells several kilometers deep often show different height-diameter ratios(H/D)because of complex geological conditions(core disking or developed fractures),which ma...Geological exploration cores obtained from shale gas wells several kilometers deep often show different height-diameter ratios(H/D)because of complex geological conditions(core disking or developed fractures),which makes further standard specimen preparation for mechanical evaluation of reservoirs difficult.In multi-cluster hydraulic fracturing,shale reservoirs between planes of hydraulic fractures with different lengths could be simplified to have different H/D ratios.Discovering the effect of H/D on the mechanical characteristics of shale specimens with different bedding orientations will support mechanical evaluation tests of reservoirs based on disked geological cores and help to optimize multicluster fracturing programs.In this study,we performed uniaxial compression tests and acoustic emission(AE)monitoring on cylindrical Longmaxi shale specimens under five bedding orientations and four H/D ratios.The experimental results showed that both the H/D-dependent mechanical properties and AE parameters demonstrated significant anisotropy.Increasing H/D did not change the uniaxial compressive strength(UCS)evolution versus bedding orientation,demonstrating a V-shaped relationship,but enhanced the curve shape.The stress level of crack damage for the specimens significantly increased with increasing H/D,excluding the specimens with a bedding orientation of 0°.With increasing H/D,the cumulative AE counts of the specimens with each bedding orientation tended to exhibit a stepped jump against the loading time.The proportion of low-average-frequency AE signals(below 100 kHz)in specimens with bedding orientations of 45°and 60°increased to over 70%by increasing H/D,but it only increased to 40%in specimens with bedding orientations of 0°,30°,and 90°.Finally,an empirical model that can reveal the effect of H/D on anisotropic UCS of shale reservoir was proposed,the anisotropic proportion of tensile and shear failure cracks in specimens under four H/D ratios was classified based on the AE data,and the effect of H/D on the anisotropic crack growth of specimens was discussed.展开更多
The characteristics of the blue core phenomenon observed in a divergent magnetic field helicon plasma are investigated using two different helical antennas, namely right-handed and lefthanded helical antennas. The mod...The characteristics of the blue core phenomenon observed in a divergent magnetic field helicon plasma are investigated using two different helical antennas, namely right-handed and lefthanded helical antennas. The mode transition, discharge image, spatial profiles of plasma density and electron temperature are diagnosed using a Langmuir probe, a Nikon D90 camera,an intensified charge-coupled device camera and an optical emission spectrometer, respectively.The results demonstrated that the blue core phenomenon appeared in the upstream region of the discharge tube at a fixed magnetic field under both helical antennas. However, it is more likely to appear in a right-handed helical antenna, in which the plasma density and ionization rate of the helicon plasma are higher. The spatial profiles of the plasma density and electron temperature are also different in both axial and radial directions for these two kinds of helical antenna. The wavelength calculated based on the dispersion relation of the bounded whistler wave is consistent with the order of magnitude of plasma length. It is proved that the helicon plasma is part of the wave mode discharge mechanism.展开更多
The efficient pyrolysis and conversion of organic matter in organic-rich shale,as well as the effective recovery of pyrolysis shale oil and gas,play a vital role in alleviating energy pressure.The state of carbon diox...The efficient pyrolysis and conversion of organic matter in organic-rich shale,as well as the effective recovery of pyrolysis shale oil and gas,play a vital role in alleviating energy pressure.The state of carbon dioxide(CO_(2))in the pyrolysis environment of shale reservoirs is the supercritical state.Its unique supercritical fluid properties not only effectively heat organic matter,displace pyrolysis products and change shale pore structure,but also achieve carbon storage to a certain extent.Shale samples were made into powder and three sizes of cores,and nitrogen(N_(2))and supercritical carbon dioxide(ScCO_(2))pyrolysis experiments were performed at different final pyrolysis temperatures.The properties and mineral characteristics of the pyrolysis products were studied based on gas chromatography analysis,Xray diffraction tests,and mass spectrometry analysis.Besides,the pore structure characteristics at different regions of cores before and after pyrolysis were analyzed using N_(2) adsorption tests to clarify the impact of fracturing degree on the pyrolysis effect.The results indicate that the optimal pyrolysis temperature of Longkou shale is about 430℃.Compared with N_(2),the oil yield of ScCO_(2) pyrolysis is higher.The pyrolysis oil obtained by ScCO_(2) extraction has more intermediate fractions and higher relative molecular weight.The ScCO_(2) can effectively improve the pore diameter of shale and its effect is better than that of N_(2).The micropores are produced in shale after pyrolysis,and the macropores only are generated in ScCO_(2) pyrolysis environments with temperatures greater than 430℃.The pore structure has different development characteristics at different pyrolysis temperatures,which are mainly affected by the pressure holding of volatile matter and products blocking.Compared to the surface of the core,the pore development effect inside the core is better.With the decrease in core size,the pore diameter,specific surface area,and pore volume of cores all increase after pyrolysis.展开更多
The gut microbiota plays a pivotal role in the maintenance of health for amphibians,and it has been fully recognized,but the effectiveness of various influencing factors has not yet been fully clarified.Although this ...The gut microbiota plays a pivotal role in the maintenance of health for amphibians,and it has been fully recognized,but the effectiveness of various influencing factors has not yet been fully clarified.Although this association should be considered while the amphibian order Caudata is facing a severe situation of population decline and extinction,there is little understanding of the association between diets and the diversity of gut microbiota in the amphibian order Caudata.Here,we conducted an extensive analysis of the gut microbiota of Cynops orientalis fed different diets using functional prediction and 16S rRNA amplicon sequencing techniques.First,we found that wild individuals had greater gut microbial diversity and richness in comparison to captive individuals.Second,we identified the bacterial taxa associated with diets and observed differences in the relative abundance of gut microbiota among people on various diets.Finally,we have a predictive comprehension of the selection and adaptative significance of shared core ASVs in the gut microbiota in maintaining the healthy survival of C.orientalis in a large-scale spatiotemporal map.Our study emphasizes how diets alter the gut microbiota of Caudata and offers fresh perspectives on the conservation and captive management of species in Caudata.展开更多
Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems ...Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems that must be resolved.To this end,a drug carrier incorporating natural magnetic cores in a zeolite framework was developed and applied to the loading of curcumin in ethanol solutions.In this system,curcumin is encapsulated in a zeolite Na(ZNA)magnetic core–shell structure(Fe@Si/ZNA),which can be easily synthesized using an in situ method.Synthesis of Fe_(3)O_(4) nanoparticles was carried out from natural materials using a co-precipitation method.Analysis of the prepared magnetic core–shell structures and composites was carried out using vibrating-sample magnetometery,Fourier transform infrared spectroscopy,transmission electron microscopy,and x-ray diffraction.The cumulative loading of curcumin in the ZNA composite with 9%nanoparticles was found to reach 90.70%with a relatively long half-life of 32.49 min.Stability tests of curcumin loading in the composite showed that adding magnetic particles to the zeolite framework also increased the stability of the composite structure.Adsorption kinetics and isotherm studies also found that the system follows the pseudo-second-order and Langmuir isotherm models.展开更多
基金the Australian Government through the Australian Research Council's Discovery Projects funding scheme(Project DP190101592)the National Natural Science Foundation of China(Grant Nos.41972280 and 52179103).
文摘The travel time of rock compressional waves is an essential parameter used for estimating important rock properties,such as porosity,permeability,and lithology.Current methods,like wireline logging tests,provide broad measurements but lack finer resolution.Laboratory-based rock core measurements offer higher resolution but are resource-intensive.Conventionally,wireline logging and rock core measurements have been used independently.This study introduces a novel approach that integrates both data sources.The method leverages the detailed features from limited core data to enhance the resolution of wireline logging data.By combining machine learning with random field theory,the method allows for probabilistic predictions in regions with sparse data sampling.In this framework,12 parameters from wireline tests are used to predict trends in rock core data.The residuals are modeled using random field theory.The outcomes are high-resolution predictions that combine both the predicted trend and the probabilistic realizations of the residual.By utilizing unconditional and conditional random field theories,this method enables unconditional and conditional simulations of the underlying high-resolution rock compressional wave travel time profile and provides uncertainty estimates.This integrated approach optimizes the use of existing core and logging data.Its applicability is confirmed in an oil project in West China.
基金Joint Fund of Research and Development Program of Henan Province,Grant/Award Number:222301420002National Natural Science Foundation of China,Grant/Award Number:U21A2064Scientific and Technological Innovation Talents in Colleges and Universities in Henan Province,Grant/Award Number:22HASTIT001。
文摘Material composition and structural design are important factors influencing the electromagnetic wave(EMW)absorption performance of materials.To alleviate the impedance mismatch attributed to the high dielectric constant of Ti_(3)C_(2)T_(x)MXene,we have successfully synthesized core‐shell structured SiO_(2)@MXene@MoS_(2)nanospheres.This architecture,comprising SiO_(2) as the core,MXene as the intermediate layer,and MoS_(2) as the outer shell,is achieved through an electrostatic self‐assembly method combined with a hydrothermal process.This complex core‐shell structure not only provides a variety of loss mechanisms that effectively dissipate electromagnetic energy but also prevents self‐aggregation of MXene and MoS_(2) nanosheets.Notably,the synergistic combination of SiO_(2) and MoS_(2) with highly conductive MXene enables the suitable dielectric constant of the composites,ensuring optimal impedance matching.Therefore,the core‐shell structured SiO_(2)@MXene@MoS_(2) nanospheres exhibit excellent EMW absorption performance,featuring a remarkable minimum reflection loss(RL_(min))of−52.11 dB(2.4 mm).It is noteworthy that these nanospheres achieve an ultra‐wide effective absorption bandwidth(EAB)of 6.72 GHz.This work provides a novel approach for designing and synthesizing high‐performance EMW absorbers characterized by“wide bandwidth and strong reflection loss.”
基金supported by the Sichuan Science and Technology Program (Grant Nos.2023NSFSC0004,2023NSFSC0790)the National Natural Science Foundation of China (Grant Nos.51827901,52304033)the Sichuan University Postdoctoral Fund (Grant No.2024SCU12093)。
文摘Deep oil and gas reservoirs are under high-temperature conditions,but traditional coring methods do not consider temperature-preserved measures and ignore the influence of temperature on rock porosity and permeability,resulting in distorted resource assessments.The development of in situ temperaturepreserved coring(ITP-Coring)technology for deep reservoir rock is urgent,and thermal insulation materials are key.Therefore,hollow glass microsphere/epoxy resin thermal insulation materials(HGM/EP materials)were proposed as thermal insulation materials.The materials properties under coupled hightemperature and high-pressure(HTHP)conditions were tested.The results indicated that high pressures led to HGM destruction and that the materials water absorption significantly increased;additionally,increasing temperature accelerated the process.High temperatures directly caused the thermal conductivity of the materials to increase;additionally,the thermal conduction and convection of water caused by high pressures led to an exponential increase in the thermal conductivity.High temperatures weakened the matrix,and high pressures destroyed the HGM,which resulted in a decrease in the tensile mechanical properties of the materials.The materials entered the high elastic state at 150℃,and the mechanical properties were weakened more obviously,while the pressure led to a significant effect when the water absorption was above 10%.Meanwhile,the tensile strength/strain were 13.62 MPa/1.3%and 6.09 MPa/0.86%at 100℃ and 100 MPa,respectively,which meet the application requirements of the self-designed coring device.Finally,K46-f40 and K46-f50 HGM/EP materials were proven to be suitable for ITP-Coring under coupled conditions below 100℃ and 100 MPa.To further improve the materials properties,the interface layer and EP matrix should be optimized.The results can provide references for the optimization and engineering application of materials and thus technical support for deep oil and gas resource development.
基金Guangzhou Key R&D Program/Plan Unveiled Flagship Project,Grant/Award Number:20220602JBGS02Guangzhou Basic and Applied Basic Research Project,Grant/Award Number:202201011449+3 种基金Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technology,Grant/Award Numbers:FC202220,FC202216Guangdong Basic and Applied Basic Research Foundation,Grant/Award Numbers:2021A1515010167,2022A1515011196National Natural Science Foundation of China,Grant/Award Numbers:21975292,21978331,22068008,52101186Training Program of the Major Research Plan of the National Natural Science Foundation of China,Grant/Award Number:92061124。
文摘Remarkable progress has characterized the field of electrocatalysis in recent decades,driven in part by an enhanced comprehension of catalyst structures and mechanisms at the nanoscale.Atomically precise metal nanoclusters,serving as exemplary models,significantly expand the range of accessible structures through diverse cores and ligands,creating an exceptional platform for the investigation of catalytic reactions.Notably,ligand‐protected Au nanoclusters(NCs)with precisely defined core numbers offer a distinct advantage in elucidating the correlation between their specific structures and the reaction mechanisms in electrocatalysis.The strategic modulation of the fine microstructures of Au NCs presents crucial opportunities for tailoring their electrocatalytic performance across various reactions.This review delves into the profound structural effects of Au NC cores and ligands in electrocatalysis,elucidating their underlying mechanisms.A detailed exploration of the fundamentals of Au NCs,considering core and ligand structures,follows.Subsequently,the interaction between the core and ligand structures of Au NCs and their impact on electrocatalytic performance in diverse reactions are examined.Concluding the discourse,challenges and personal prospects are presented to guide the rational design of efficient electrocatalysts and advance electrocatalytic reactions.
基金the Iranian Nanotechnology Development Committee for their financial supportUniversity of Kashan for supporting this work by Grant No. 1223097/10the micro and nanomechanics laboratory by Grant No. 14022023/5
文摘Curved shells are increasingly utilized in applied engineering due to their shared characteristics with other sandwich structures,flexibility,and attractive appearance.However,the inability of controlling and regulating vibrations and destroying them afterward is a challenge to scientists.In this paper,the curve shell equations and a linear quadratic regulator are adopted for the state feedback design to manage the structure vibrations in state space forms.A five-layer sandwich doubly curved micro-composite shell,comprising two piezoelectric layers for the sensor and actuator,is modeled by the fourth-order shear deformation theory.The core(honeycomb,truss,and corrugated)is analyzed for the bearing of transverse shear forces.The results show that the honeycomb core has a greater effect on the vibrations.When the parameters related to the core and the weight percentage of graphene increase,the frequency increases.The uniform distribution of graphene platelets results in the lowest natural frequency while the natural frequency increases.Furthermore,without taking into account the piezoelectric layers,the third-order shear deformation theory(TSDT)and fourth-order shear deformation theory(FOSDT)align closely.However,when the piezoelectric layers are incorporated,these two theories diverge significantly,with the frequencies in the FOSDT being lower than those in the TSDT.
基金supported by the National Natural Science Foundation of China (Grant No.11902157)Natural Science Foundation of Jiangsu Province (Grant No.BK20180417)the Scientific and Technological Innovation Project of Army Engineering Univeristy of PLA (Grant No.KYGYZXJK150025)。
文摘An innovative multi-layer composite explosion containment vessel(CECV)utilizing a sliding steel platealuminum honeycomb-fiber cloth sandwich is put forward to improve the anti-explosion capacity of a conventional single-layer explosion containment vessel(SECV).Firstly,a series of experiments and finite element(FE)simulations of internal explosions are implemented to understand the basic anti-explosion characteristics of a SECV and the rationality of the computational models and methods is verified by the comparison between the experimental results and simulation results.Based on this,the CECV is designed in detail and a variety of FE simulations are carried out to investigate effects of the sandwich structure,the explosive quantity and the laying mode of the fiber cloth on anti-explosion performance and dynamic response of the CECV under internal explosions.Simulation results indicate that the end cover is the critical position for both the SECV and CECV.The maximum pressure of the explosion shock wave and the maximum strain of the CECV can be extremely declined compared to those of the SECV.As a result,the explosive quantity the CECV can sustain is up to 20 times of that the SECV can sustain.Besides,as the explosive quantity increases,the internal pressure of the CECV keeps growing and the plastic deformation and failure of the sandwich structure become more and more severe,yielding plastic strain of the CECV in addition to elastic strain.The results also reveal that the laying angles of the fiber cloth's five layers have an impact on the anti-explosion performance of the CECV.For example,the CECV with fiber cloth layered in 0°/45°/90°/45°/0°mode has the optimal anti-capacity,compared to 0°/0°/0°/0°/0°and 0°/30°/60°/30°/0°modes.Overall,owing to remarkable anti-explosion capacity,this CECV can be regarded as a promising candidate for explosion resistance.
基金financially supported by the National Natural Science Foundation of China (22279152,U21A20331)the National Science Fund for Distinguished Young Scholars (21925506)+1 种基金the Ningbo key scientific and technological project (2022Z117)the Ningbo Natural Science Foundation (2021J192)。
文摘Phenazine-based non-fullerene acceptors(NFAs)have demonstrated great potential in improving the power conversion efficiency(PCE)of organic solar cells(OSCs).Halogenation is known to be an effective strategy for increasing optical absorption,refining energy levels,and improving molecular packing in organic semiconductors.Herein,a series of NFAs(Pz IC-4H,Pz IC-4F,Pz IC-4Cl,Pz IC-2Br)with phenazine as the central core and with/without halogen-substituted(dicyanomethylidene)-indan-1-one(IC)as the electron-accepting end group were synthesized,and the effect of end group matched phenazine central unit on the photovoltaic performance was systematically studied.Synergetic photophysical and morphological analyses revealed that the PM6:Pz IC-4F blend involves efficient exciton dissociation,higher charge collection and transfer rates,better crystallinity,and optimal phase separation.Therefore,OSCs based on PM6:Pz IC-4F as the active layer exhibited a PCE of 16.48%with an open circuit voltage(Voc)and energy loss of 0.880 V and 0.53 e V,respectively.Accordingly,this work demonstrated a promising approach by designing phenazine-based NFAs for achieving high-performance OSCs.
基金Project supported by the National Natural Science Foundation of China (Nos. 12172339 and 11732005)the Beijing Natural Science Foundation of China (No. 1222006)。
文摘A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed,and its sound insulation and optimization are investigated.First,the motion governing equation of the sandwich plate is established by the third-order shear deformation theory(TSDT),and then combined with the fluid-structure coupling conditions,and the sound insulation is solved.The theoretical results are validated by COMSOL simulation results,and the effects of the structural parameter on the sound insulation are analyzed.Finally,the standard genetic algorithm is adopted to optimize the sound insulation of the sandwich plate.
基金supported and funded by the Researchers Supporting Project(Project No.RSPD2024R781),King Saud University,Riyadh,Saudi Arabia。
文摘Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic development.Thirty-three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic minerals.These samples included gneisses rocks,monzogranite,and metavolcano-sedimentary rocks for both the Thalbah and Bayda groups.Using the Rf/j and Fry methods,the axial ratios(XZ)range about 2.20 to 7.10 and 1.90 to 9.10,respectively.For various rock units,the strain measurements show moderate to highly deformation.Most of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain(X).The short axes(Z)based to be subvertical foliation related with a subhorizontal foliation.The results demonstrate that contacts generated at semi-brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic units.It concluded that nappe generation in orogens results from pure shear deformation.
基金Supported by the National Natural Science Foundation of China(No.41976075)the National Key Research and Development Program of China(No.2021YFF0501302)+1 种基金the Fundamental Research Funds for National Non-profit Institute Grant(No.JG 2103)the China Ocean Mineral Resources R&D Association Project(No.DY135-S 2-1-03)。
文摘A new hydrothermal field(Tianshi)was discovered on the rift valley wall through plume anomaly surveys and geological work conducted in 2012 and 2018 between 2°35′N and 2°43′N of the slow-spreading Carlsberg Ridge(CR).Here,the results of two expeditions conducted to detect and characterize the new hydrothermal field are reported.Mineralogical and geochemical data,as well as 14 C ages of a sediment core collected near the field are presented to reveal the hydrothermal history.Results show that the Tianshi field is a basalt-hosted hydrothermal system.Geochemical data of the sediments collected near the field indicate a strong hydrothermal contribution,and hydrothermal Fe and Cu fluxes range from 30 to 155 mg/(cm^(2)·ka)and 0.59 to 11.49 mg/(cm^(2)·ka),respectively.Temporal variations in the fluxes of hydrothermal Fe indicate that there have been at least three amplified hydrothermal venting events(H 1,H 2,and H 3)in the Tianshi field over the last 35.2 ka,in 28.6-35.2 ka BP,22.0-27.6 ka BP,and 1.2-11.4 ka BP,respectively.Hydrothermal event H 2 was driven by an increased magmatic production associated with sea level fall during the Last Glacial Maximum,while event H 3 was promoted by tectonic activity associated with a rapid sea level rise.This study further verified the role of sea level change in modulating hydrothermal activity on mid-ocean ridges.
基金supported by the National Science Foundation of China(Grant No.42230606)。
文摘Here,a nonhydrostatic alternative scheme(NAS)is proposed for the grey zone where the nonhydrostatic impact on the atmosphere is evident but not large enough to justify the necessity to include an implicit nonhydrostatic solver in an atmospheric dynamical core.The NAS is designed to replace this solver,which can be incorporated into any hydrostatic models so that existing well-developed hydrostatic models can effectively serve for a longer time.Recent advances in machine learning(ML)provide a potential tool for capturing the main complicated nonlinear-nonhydrostatic relationship.In this study,an ML approach called a neural network(NN)was adopted to select leading input features and develop the NAS.The NNs were trained and evaluated with 12-day simulation results of dry baroclinic-wave tests by the Weather Research and Forecasting(WRF)model.The forward time difference of the nonhydrostatic tendency was used as the target variable,and the five selected features were the nonhydrostatic tendency at the last time step,and four hydrostatic variables at the current step including geopotential height,pressure in two different forms,and potential temperature,respectively.Finally,a practical NAS was developed with these features and trained layer by layer at a 20-km horizontal resolution,which can accurately reproduce the temporal variation and vertical distribution of the nonhydrostatic tendency.Corrected by the NN-based NAS,the improved hydrostatic solver at different horizontal resolutions can run stably for at least one month and effectively reduce most of the nonhydrostatic errors in terms of system bias,anomaly root-mean-square error,and the error of the wave spatial pattern,which proves the feasibility and superiority of this scheme.
文摘Purpose:The collaboration relationships between innovation actors at a geographic level may be considered as grouping two separate layers,the domestic and the foreign.At the level of each layer,the relationships and the actors involved constitute a Triple Helix game.The paper distinguished three levels of analysis:the global grouping together all actors,the domestic grouping together domestic actors,and the foreign related to only actors from partner countries.Design/methodology/approach:Bibliographic records data from the Web of Science for South Korea and West Africa breakdown per innovation actors and distinguishing domestic and international collaboration are analyzed with game theory.The core,the Shapley value,and the nucleolus are computed at the three levels to measure the synergy between actors.Findings:The synergy operates more in South Korea than in West Africa;the government is more present in West Africa than in South Korea;domestic actors create more synergy in South Korea,but foreign more in West Africa;South Korea can consume all the foreign synergy,which is not the case of West Africa.Research limitations:Research data are limited to publication records;techniques and methods used may be extended to other research outputs.Practical implications:West African governments should increase their investment in science,technology,and innovation to benefit more from the synergy their innovation actors contributed at the foreign level.However,the results of the current study may not be sufficient to prove that greater investment will yield benefits from foreign synergies.Originality/value:This paper uses game theory to assess innovation systems by computing the contribution of foreign actors to knowledge production at an area level.It proposes an indicator to this end.
基金funded by the National Natural Science Foundation of China(Grant Nos.51927808,52174098 and 52374151).
文摘Geological exploration cores obtained from shale gas wells several kilometers deep often show different height-diameter ratios(H/D)because of complex geological conditions(core disking or developed fractures),which makes further standard specimen preparation for mechanical evaluation of reservoirs difficult.In multi-cluster hydraulic fracturing,shale reservoirs between planes of hydraulic fractures with different lengths could be simplified to have different H/D ratios.Discovering the effect of H/D on the mechanical characteristics of shale specimens with different bedding orientations will support mechanical evaluation tests of reservoirs based on disked geological cores and help to optimize multicluster fracturing programs.In this study,we performed uniaxial compression tests and acoustic emission(AE)monitoring on cylindrical Longmaxi shale specimens under five bedding orientations and four H/D ratios.The experimental results showed that both the H/D-dependent mechanical properties and AE parameters demonstrated significant anisotropy.Increasing H/D did not change the uniaxial compressive strength(UCS)evolution versus bedding orientation,demonstrating a V-shaped relationship,but enhanced the curve shape.The stress level of crack damage for the specimens significantly increased with increasing H/D,excluding the specimens with a bedding orientation of 0°.With increasing H/D,the cumulative AE counts of the specimens with each bedding orientation tended to exhibit a stepped jump against the loading time.The proportion of low-average-frequency AE signals(below 100 kHz)in specimens with bedding orientations of 45°and 60°increased to over 70%by increasing H/D,but it only increased to 40%in specimens with bedding orientations of 0°,30°,and 90°.Finally,an empirical model that can reveal the effect of H/D on anisotropic UCS of shale reservoir was proposed,the anisotropic proportion of tensile and shear failure cracks in specimens under four H/D ratios was classified based on the AE data,and the effect of H/D on the anisotropic crack growth of specimens was discussed.
基金supported by the Beijing Municipal Natural Science Foundation (No. 1242015)Discipline Construction of Material Science and Engineering (Nos. 21090122014 and 21090123007)。
文摘The characteristics of the blue core phenomenon observed in a divergent magnetic field helicon plasma are investigated using two different helical antennas, namely right-handed and lefthanded helical antennas. The mode transition, discharge image, spatial profiles of plasma density and electron temperature are diagnosed using a Langmuir probe, a Nikon D90 camera,an intensified charge-coupled device camera and an optical emission spectrometer, respectively.The results demonstrated that the blue core phenomenon appeared in the upstream region of the discharge tube at a fixed magnetic field under both helical antennas. However, it is more likely to appear in a right-handed helical antenna, in which the plasma density and ionization rate of the helicon plasma are higher. The spatial profiles of the plasma density and electron temperature are also different in both axial and radial directions for these two kinds of helical antenna. The wavelength calculated based on the dispersion relation of the bounded whistler wave is consistent with the order of magnitude of plasma length. It is proved that the helicon plasma is part of the wave mode discharge mechanism.
基金supported by the National Natural Science Foundation of China (Nos.U22B6004,51974341)State Key Laboratory of Deep Oil and Gas (No.SKLDOG2024-ZYTS-14)the Fundamental Research Funds for the Central Universities (No.20CX06070A)。
文摘The efficient pyrolysis and conversion of organic matter in organic-rich shale,as well as the effective recovery of pyrolysis shale oil and gas,play a vital role in alleviating energy pressure.The state of carbon dioxide(CO_(2))in the pyrolysis environment of shale reservoirs is the supercritical state.Its unique supercritical fluid properties not only effectively heat organic matter,displace pyrolysis products and change shale pore structure,but also achieve carbon storage to a certain extent.Shale samples were made into powder and three sizes of cores,and nitrogen(N_(2))and supercritical carbon dioxide(ScCO_(2))pyrolysis experiments were performed at different final pyrolysis temperatures.The properties and mineral characteristics of the pyrolysis products were studied based on gas chromatography analysis,Xray diffraction tests,and mass spectrometry analysis.Besides,the pore structure characteristics at different regions of cores before and after pyrolysis were analyzed using N_(2) adsorption tests to clarify the impact of fracturing degree on the pyrolysis effect.The results indicate that the optimal pyrolysis temperature of Longkou shale is about 430℃.Compared with N_(2),the oil yield of ScCO_(2) pyrolysis is higher.The pyrolysis oil obtained by ScCO_(2) extraction has more intermediate fractions and higher relative molecular weight.The ScCO_(2) can effectively improve the pore diameter of shale and its effect is better than that of N_(2).The micropores are produced in shale after pyrolysis,and the macropores only are generated in ScCO_(2) pyrolysis environments with temperatures greater than 430℃.The pore structure has different development characteristics at different pyrolysis temperatures,which are mainly affected by the pressure holding of volatile matter and products blocking.Compared to the surface of the core,the pore development effect inside the core is better.With the decrease in core size,the pore diameter,specific surface area,and pore volume of cores all increase after pyrolysis.
基金funded by the National Natural Science Foundation of China(31901120 and 31700320)China Postdoctoral Science Foundation(2022M723135)+2 种基金Beijing Natural Science Foundation(5192016)Anhui Provincial Key Laboratory of the Conservation and Exploitation of Biological Resources(swzy202006)Innovation and Entrepreneurship Training Program for college students of Anhui Normal University.
文摘The gut microbiota plays a pivotal role in the maintenance of health for amphibians,and it has been fully recognized,but the effectiveness of various influencing factors has not yet been fully clarified.Although this association should be considered while the amphibian order Caudata is facing a severe situation of population decline and extinction,there is little understanding of the association between diets and the diversity of gut microbiota in the amphibian order Caudata.Here,we conducted an extensive analysis of the gut microbiota of Cynops orientalis fed different diets using functional prediction and 16S rRNA amplicon sequencing techniques.First,we found that wild individuals had greater gut microbial diversity and richness in comparison to captive individuals.Second,we identified the bacterial taxa associated with diets and observed differences in the relative abundance of gut microbiota among people on various diets.Finally,we have a predictive comprehension of the selection and adaptative significance of shared core ASVs in the gut microbiota in maintaining the healthy survival of C.orientalis in a large-scale spatiotemporal map.Our study emphasizes how diets alter the gut microbiota of Caudata and offers fresh perspectives on the conservation and captive management of species in Caudata.
基金funding from the Ministry of Education,Culture,Research,and Technology,Indonesia,through the PDKN Research Grant with Contract No.041/E5/PG.02.00.PL/2023.
文摘Curcumin is a natural polyphenol that is used in various traditional medicines.However,its inherent properties,such as its rapid degradation and metabolism,low bioavailability,and short half-life,are serious problems that must be resolved.To this end,a drug carrier incorporating natural magnetic cores in a zeolite framework was developed and applied to the loading of curcumin in ethanol solutions.In this system,curcumin is encapsulated in a zeolite Na(ZNA)magnetic core–shell structure(Fe@Si/ZNA),which can be easily synthesized using an in situ method.Synthesis of Fe_(3)O_(4) nanoparticles was carried out from natural materials using a co-precipitation method.Analysis of the prepared magnetic core–shell structures and composites was carried out using vibrating-sample magnetometery,Fourier transform infrared spectroscopy,transmission electron microscopy,and x-ray diffraction.The cumulative loading of curcumin in the ZNA composite with 9%nanoparticles was found to reach 90.70%with a relatively long half-life of 32.49 min.Stability tests of curcumin loading in the composite showed that adding magnetic particles to the zeolite framework also increased the stability of the composite structure.Adsorption kinetics and isotherm studies also found that the system follows the pseudo-second-order and Langmuir isotherm models.