Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force ...Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.展开更多
As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of ai...As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of aircraft structures. The assessment of electromagnetic SE for Slotted Composite Structures(SCSs) is particularly challenging due to their complex geometries and there remains a lack of suitable models for accurately predicting the SE performance of these intricate configurations. To address this issue, this paper introduces SCS-Net, a Deep Neural Network (DNN) method designed to accurately predict the SE of SCS. This method considers the impacts of various structural parameters, material properties and incident wave parameters on the SE of SCSs. In order to better model the SCS, an improved Nicolson-Ross-Weir (NRW) method is introduced in this paper to provide an equivalent flat structure for the SCS and to calculate the electromagnetic parameters of the equivalent structure. Additionally, the prediction of SE via DNNs is limited by insufficient test data, which hinders support for large-sample training. To address the issue of limited measured data, this paper develops a Measurement-Computation Fusion (MCF) dataset construction method. The predictions based on the simulation results show that the proposed method maintains an error of less than 0.07 dB within the 8–10 GHz frequency range. Furthermore, a new loss function based on the weighted L1-norm is established to improve the prediction accuracy for these parameters. Compared with traditional loss functions, the new loss function reduces the maximum prediction error for equivalent electromagnetic parameters by 47%. This method significantly improves the prediction accuracy of SCS-Net for measured data, with a maximum improvement of 23.88%. These findings demonstrate that the proposed method enables precise SE prediction and design for composite structures while reducing the number of test samples needed.展开更多
This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silic...This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.展开更多
Materials engineering plays a key role in the field of electrochemical energy storage,and considerable efforts have been made in recent years to fulfill the future requirements of electrochemical energy storage using ...Materials engineering plays a key role in the field of electrochemical energy storage,and considerable efforts have been made in recent years to fulfill the future requirements of electrochemical energy storage using novel functional electrode materials.Materials with hollow structures are of particular interests due to their low density,large specific surface area and high porosity,making them promising candidates for energy conversion and storage.The Kirkendall effect has been widely applied for the synthesis of nanoscale hollow structures,which involves an unbalanced counter diffusion through a reaction interface.Herein,the recent progress on the use of the nanoscale Kirkendall effect to synthesize hollow nanostructures,including nanoparticles,one-dimensional(1-D),two-dimensional(2-D),and three-dimensional(3-D)nanostructures,and their potential applications in energy storage devices are summarized and discussed.And prospects is made for the future development of this research field.展开更多
A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).Th...A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).The results revealed that Ho_(2)CoMnO_(6) crystallizes in a monoclinic structure with the P2_(1)/n space group.In contrast,the other compounds HoRCoMnO_(6)(R=Gd,Eu,or Nd) exhibit an orthorhombic structure with the Pnma space group.As a result,the average crystallite size also changes as a function of rare-earth element doping.This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements.The Curie temperature T_C,for example,increases from 80 to 118℃ with the ionic radii of rare earths increasing.Furthermore,the study of the magnetocaloric effect(MCE) shows that the maximum of the entropy variation(-ΔS_(M)^(max)) increases from 4.97 to 6.06 J/(kg·K) under a magnetic field of 5 T with substitution by rare-earth ions.To examine the efficiency of MCE materials,the relative cooling power(RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd.The mean entropy variation with tempe rature(TEC) was also studied.Due to their significant magnetocaloric performance,HoRCoMnO_(6)(noted as HRCMO) compounds(with R=Ho,Gd,Eu or Nd) could be good candidates for low-temperature magnetic cooling applications.展开更多
In 2018,Baige,Xizang,witnessed two consecutive large-scale landslides,causing significant damage and drawing widespread attention.From March 2011 to February 2018,the Baige landslide exhibited a 50-m displacement with...In 2018,Baige,Xizang,witnessed two consecutive large-scale landslides,causing significant damage and drawing widespread attention.From March 2011 to February 2018,the Baige landslide exhibited a 50-m displacement without complete failure,culminating in a collapse in October 2018.The mechanisms behind its resistance to failure despite substantial deformation and the influence of the complex geo-structure within the tectonic mélange belt remain unclear.To address these questions,this study utilized a multidisciplinary approach,integrating on-site geological field mapping,surface deformation monitoring,multielectrode resistivity method,and deep displacement analysis.The aim was to evaluate the impact of the intricate geo-structure within the tectonic mélange belt on the Baige landslide events.Findings reveal that the landslide's geo-structure consists of structurally fractured,mesh-like rock masses,including heterogeneous lenticular rock masses and intermittent brittle shear zones distributed around the lens-shaped rock masses.The study underscores that the inhomogeneous and weakly deformed lenticular rock masses function as natural locked segments,governing the stability of the Baige landslide.Specifically,the relatively intact and hard granodiorite porphyry play a crucial role in locking the landslide's deformation.Deep displacement analysis indicates that the brittle shear zones act as the sliding surfaces.The progressive destruction of the locked segments and the gradual penetration of brittle shear zones,driven by gravitational potential energy,contribute to the landslide occurrence.This research provides critical insights into the formation mechanisms of large-scale landslides within tectonic mélange belts.展开更多
Exploring carbon emission effects based on the evolution of residents’ dietary structure to achieve the carbon neutrality goal and mitigate climate change is an important task.This study took China as the research ob...Exploring carbon emission effects based on the evolution of residents’ dietary structure to achieve the carbon neutrality goal and mitigate climate change is an important task.This study took China as the research object(data excluding Hong Kong,Macao and Taiwan) and used the carbon emission coefficient method to quantitatively measure the food carbon emissions from 1987–2020,then analyzed the carbon emission effects under the evolution of dietary structure.The results showed that during the study period,the Chinese dietary structure gradually changed to a high-carbon consumption pattern.The dietary structure of urban residents developed to a balanced one,while that of rural residents developed to a high-quality one.During the study period,the per capita food carbon emissions and total food consumption of Chinese showed an increasing trend.The per capita food carbon emissions of residents in urban and rural showed an overall upward trend.The total food carbon emissions in urban increased significantly,while that in rural increased first and then decreased.The influence of beef and mutton on carbon emissions is the highest in dietary structure.Compared with the balanced dietary pattern,the food carbon emissions of Chinese residents had not yet reached the peak,but were evolving to a high-carbon consumption pattern.展开更多
The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high deman...The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its application.To achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution process.Microstructural evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension tests.The findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing seam.The effects of grain size,such as pinning and splitting,are amplified at higher brazing temperatures.Additionally,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture mode.The fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack path.Therefore,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.展开更多
The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which i...The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which is mathematically expressed as Meff = （（σ1-σ3） L.sin 2α sin α）/2, where σ1-σ3 represents the yield strength of the related rock, L is a unit length and a is the angle between σ1 and deformation bands. This criterion demonstrates that the maximum value appears at angles of ±54.7° to σ1 and there is a slight difference in the moment in the range of 55°±10°. The range covers the whole observations available from nature and experiments. Its major implications include： （1） it can be used to determine the stress state when the related deformation features formed; （2） it provides a new approach to determine the Wk of the related ductile shear zone if only the ratio of the vorticity and strain rate remains fixed; （3） It can be used to explain （a） the obtuse angle in the contraction direction of conjugate kink-bands and extensional crenulation cleavages, （b） formation of low-angle normal faults and high-angle reverse faults, （c） lozenge ductile shear zones in basement terranes, （d） some crocodile structures in seismic profiles and （e） detachment folds in foreland basins.展开更多
In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X...In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM).We analyzed their lipidlowering properties in vitro(water holding,oil holding swelling cholesterol and sodium cholate binding capacitises)and the hypolipidemic effects in mice.The results showed that tremella dietary fibers presented the infrared absorption spectrum characteristics of polysaccharides and the characteristic diffraction peaks of cellulose type I.SEM results indicated that the surface of insoluble dietary fiber(IDF)was porous,while the soluble dietary fiber(SDF)was relatively compact and spongy.IDF exhibited significantly higher water holding,oil holding,and swelling binding capacities than the corresponding SDF.However,SDF exhibited significantly higher viscosity than IDF.The results showed tremella dietary fibers were significant in swelling,water holding and oil holding,cholesterol and bile acids.In vivo experiment results in mice indicated that SDF has the best effect on hyperlipidemia mice than IDF and total dietary fiber(TDF).SDF showed that the total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)contents dropped by 28.33%,18.65%,and 48.97%,respectively,while high density lipoprotein cholesterol(HDL-C)content increased by 43.80%.Compared with the high-fat control(HCM)group,the arteriosclerosis index(AI)and liver index(LI)of the SDF group mice showed significant differences,indicating that SDF has a good auxiliary effect of lowering blood lipids.The administration of tremella fibers improved the lipid metabolism disorderly situation of hyperlipidemia mice.These results provide a reference for further research and rational development of T.fuciformis.展开更多
A water-soluble polysaccharide,designated BFP-3,was isolated from Bangia fuscopurpurea by hot water extraction,anion-exchange,and size-exclusion chromatography and tested to determine its antitumor activity.The struct...A water-soluble polysaccharide,designated BFP-3,was isolated from Bangia fuscopurpurea by hot water extraction,anion-exchange,and size-exclusion chromatography and tested to determine its antitumor activity.The structural characteristics of BFP-3 were investigated by chemical and spectroscopic methods,including partial acid hydrolysis,methylation analysis,one-and two-dimensional nuclear magnetic resonance,and gas chromatography-mass spectrometry.The results showed that BFP-3 was mainly comprised of rhamnose,arabinose,mannose,glucose,and galactose.Moreover,the weight-average molecular weight of BFP-3 was estimated to be approximately 333 kDa.The backbone of BFP-3 was primarily composed of repeating 5-α-l-Araf-1→(4-α-d-Glcp-1)_(4)→4,6-β-d-Manp-1 units,and the side chains consisted of repeatingβ-d-Galp-1→(4-β-d-Galp-1)_(4)→4,6-β-d-Galp-1→3,4-α-l-Rhap,β-l-Arap-1→(3-β-d-Galp-1)_(3),andβ-l-Arap-1 units.Counting Kit-8 assays revealed that BFP-3 significantly inhibited the proliferation of A2780,COC1,SKOV3,HO-8910,and OVCAR3 ovarian cancer cells in vitro,indicating that BFP-3 could have potential applications in the treatment of ovarian cancer.展开更多
Ions or molecules are said to be isoelectronic if they are composed of different elements but have the same number of electrons, the same number of covalent bonds and the same structure. This criterion is unfortunatel...Ions or molecules are said to be isoelectronic if they are composed of different elements but have the same number of electrons, the same number of covalent bonds and the same structure. This criterion is unfortunately not sufficient to ensure that a chemical structure is a valid chemical compound. In a previous article, a procedure has been described to draw 2D valid structural formulas: the even-odd rule. This rule has been applied first to single-bonded molecules then to single-charged single-bonded ions. It covers hypovalent, hypervalent or classic Lewis’ octet compounds. The funding principle of the even-odd rule is that each atom of the compound possesses an outer-shell filled only with pairs of electrons. The application of this rule guarantees validity of any single-covalent-bond chemical structure. In the present paper, this even-odd rule and its electron-pair criterion are checked for coherence with an effective-valence isoelectronic rule using numerous known compounds having single-covalent-bond connections. The test addresses Lewis’ octet ions or molecules as well as hypovalent and hypervalent compounds. The article concludes that the even-odd rule and the effective-valence isoelectronicity rule are coherent for known single-covalent-bond chemical compounds.展开更多
We designed a clamping device to study lateral photovoltaic effect (LPE) in Ni-SiO_(2)-Si structure with bias due to the appropriate barrier height.The LPE has a prominent sensitivity and linearity with 532 nm wavelen...We designed a clamping device to study lateral photovoltaic effect (LPE) in Ni-SiO_(2)-Si structure with bias due to the appropriate barrier height.The LPE has a prominent sensitivity and linearity with 532 nm wavelength laser.The transient response time is 450μs and the relaxation time is 2 250μs in the Ni-SiO_(2)-Si structure without bias.The LPE sensitivity has a significant improvement with bias.The transient response time is 6μs and the relaxion time is 47μs with-7 V bias,not only improving the LPE sensitivity,but also increasing the response speed with bias.The research shows that the Schottky barrier structure can improve the sensitivity and linearity of LPE with bias effectively,and thus it can be used in position sensitive sensors.展开更多
The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to atte...The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier.Our results show that the ideal strengths of C_(4)N_(4)under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28,respectively.The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C_(4)N_(4).The orderly bond-rearranging behaviors under the weak tensile loading path along the[100]direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition.The present results enrich the knowledge of the structure and electronic properties of C_(4)N_(4)under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.展开更多
Understanding the properties of nuclei near the double magic nucleus^(40)Ca is crucial for both nuclear theory and experiments.In this study,Ca isotopes were investigated using an extended pairing-plus-quadrupole mode...Understanding the properties of nuclei near the double magic nucleus^(40)Ca is crucial for both nuclear theory and experiments.In this study,Ca isotopes were investigated using an extended pairing-plus-quadrupole model with monopole corrections.The negative-parity states of^(44)Ca were coupled with the intruder orbital g_(9/2)at 4 MeV.The values of E_(4+)/E_(2+)agree well with experimental trend from^(42)Ca to^(50)Ca,considering monopole effects between νf_(7/2)and νp_(3/2)(νf_(5/2)).This monopole effect,determined from data of^(48)Ca and^(50)Ca,supports the proposed new nuclear magic number N=34 by predicting a high-energy 2^(+)state in^(54)Ca.展开更多
Structural colors originated from Mie scattering of dielectric spheres can be regulated by the coupling effect between them and substrates.Here a rapid visual identification method of silver ornaments was proposed by ...Structural colors originated from Mie scattering of dielectric spheres can be regulated by the coupling effect between them and substrates.Here a rapid visual identification method of silver ornaments was proposed by the coupling effect of Zn O spheres with them.Both simulation and experimental results proved that,by coupling with different metal substrates,the Mie resonance scattering peaks of ZnO spheres with dimeter of 700 nm showed different degrees of redshift,which lead to different structural color appeared when ZnO spheres deposited on different metal surfaces with a similar appearance.A red structural color was displayed on the surface of the real silver ornament and a yellow-green structural color was shown on the surface of the cupronickel ornament.This method is quite simple and low-cost because it only needs to spray the dispersion of ZnO spheres on the ornament surface.Due to the mild chemical properties of the ZnO,covering and erasing ZnO spheres on the surface of silver would not corrode the silver ornament.Finally,an atomizer method was used for portable and daily testing.This work opens new perspectives on the visual identification of silver.展开更多
Organic–inorganic lead halide perovskites(LHPs) have attracted great interest owing to their outstanding optoelectronic properties.Typically,the underlying electronic structure would determinate the physical properti...Organic–inorganic lead halide perovskites(LHPs) have attracted great interest owing to their outstanding optoelectronic properties.Typically,the underlying electronic structure would determinate the physical properties of materials.But as for now,limited studies have been done to reveal the underlying electronic structure of this material system,comparing to the huge amount of investigations on the material synthesis.The effective mass of the valance band is one of the most important physical parameters which plays a dominant role in charge transport and photovoltaic phenomena.In pristine CsPbBr_(3),the Fr?hlich polarons associated with the Pb–Br stretching modes are proposed to be responsible for the effective mass renormalization.In this regard,it would be very interesting to explore the electronic structure in doped LHPs.Here,we report high-resolution angle-resolved photoemission spectroscopy(ARPES) studies on both pristine and Cl-doped CsPbBr_(3).The experimental band dispersions are extracted from ARPES spectra along both ■ and ■ high symmetry directions.DFT calculations are performed and directly compared with the ARPES data.Our results have revealed the band structure of Cl-doped CsPbBr_(3) for the first time,which have also unveiled the effective mass renormalization in the Cl-doped CsPbBr_(3) compound.Doping dependent measurements indicate that the chlorine doping could moderately tune the renormalization strength.These results will help understand the physical properties of LHPs as a function of doping.展开更多
Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capit...Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capital and the social capital structure.The results show the following:first,social capital can expand the household income gap,and the effect of this index on the household income gap is 7.54%.Second,the indexes of the social capital dimension can expand the household income gap,and the structural effects of the household income gap on social networks,social trust,and social participation are 3.17%,3.64%,and 0.65%,respectively.Third,no dimension of the path is the same as the effect on the household income gap.展开更多
2-（2,3-Dihydroxpropyliminomethyl）6-methoxyphenol（H3L）, trimethylacetic acid（Hpiv）, Gd（NO3）3·6 H2O and Co（NO3）2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2（L...2-（2,3-Dihydroxpropyliminomethyl）6-methoxyphenol（H3L）, trimethylacetic acid（Hpiv）, Gd（NO3）3·6 H2O and Co（NO3）2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2（L）2（μ3-OH）2（piv）6]·2 Hpiv·2 CH3OH（1）. X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798（6）, b = 12.0877（5）, c = 15.0367（7） ?, α = 67.320（4）°, β = 81.583（4）°, γ = 75.201（4）°, V =1939.62（18） ?3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ（I）. In magnetization study, heterometallic 1 exhibits magnetocaloric effect（MCE） of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.展开更多
The size of pores or the grille spacing of water–sediment separation structures directly affects their regulation effect on the debris flow performance.A suitable pore size or grille spacing can effectively improve t...The size of pores or the grille spacing of water–sediment separation structures directly affects their regulation effect on the debris flow performance.A suitable pore size or grille spacing can effectively improve the water–sediment separation ability of the structure.The new funnel-type grating water–sediment separation structure(FGWSS)combines vertical and horizontal structures and provides a satisfactory water–sediment separation effect.However,the regulation effect of the grille spacing of the structure on the debris flow performance has not been studied.The regulation effect of the structure grille spacing on the debris flow performance is studied through a flume test,and the optimal structure grille spacing is obtained.An empirical equation of the relationship between the relative grille spacing of the structure and the sediment separation rate is established.Finally,the influence of the water–sediment separation structure on the regulation effect of debris flows is examined from two aspects:external factors(properties of debris flows)and internal factors(structural factors).The experimental results show that the gradation characteristics of solid particles in debris flows constitute a key factor affecting the regulation effect of the structure on the debris flow performance.The optimum grille spacing of the FGWSS matches the particle size corresponding to the material distribution curves d85~d90 of the debris flow.The total separation rate of debris flow particles is related to the grille spacing of the structure and the content of coarse and fine particles in the debris flow.展开更多
基金The National Natural Science Foundation of China(No.52222804,U21A20154).
文摘Past investigations of the hydrodynamic forces on vertical columns have generally been based on rigid structure assumptions.The effects of structural flexibility and geometry characteristics on the hydrodynamic force distribution are not well understood.In this study,fluid-structure interaction models are developed for numerical analyses.This modeling technique is verified with an experimental test in the literature using both circular and rectangular cross-sections.A series of material elasticities that present structural properties ranging from rigid to flexible is then used to conduct analyses.This finding indicates that an increase in structural flexibility can decrease the impact force to some extent,but this effect is limited.A concrete bridge pier with fluid flow impact can be considered rigid when it is fixed at the bottom.After that,the effects of the initial downstream water height and the width of water tank on the hydrodynamic force are thoroughly investigated.The results demonstrate that the increase in the downstream water height with a constant upstream water height corresponds to a decreased force.Moreover,the vertical column results in a blockage effect on the fluid flow.The greater the blockage effect,the higher the hydrodynamic force.The blockage effect from the vertical column can be neglected when the tank width is greater than eight times the structural cross-section diameter.
基金supported by the National Natural Science Foundation of China(Nos.62101020 and 62141405)the Special Scientific Research Project of Civil Aircraft,China(No.MJZ5-2N22).
文摘As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of aircraft structures. The assessment of electromagnetic SE for Slotted Composite Structures(SCSs) is particularly challenging due to their complex geometries and there remains a lack of suitable models for accurately predicting the SE performance of these intricate configurations. To address this issue, this paper introduces SCS-Net, a Deep Neural Network (DNN) method designed to accurately predict the SE of SCS. This method considers the impacts of various structural parameters, material properties and incident wave parameters on the SE of SCSs. In order to better model the SCS, an improved Nicolson-Ross-Weir (NRW) method is introduced in this paper to provide an equivalent flat structure for the SCS and to calculate the electromagnetic parameters of the equivalent structure. Additionally, the prediction of SE via DNNs is limited by insufficient test data, which hinders support for large-sample training. To address the issue of limited measured data, this paper develops a Measurement-Computation Fusion (MCF) dataset construction method. The predictions based on the simulation results show that the proposed method maintains an error of less than 0.07 dB within the 8–10 GHz frequency range. Furthermore, a new loss function based on the weighted L1-norm is established to improve the prediction accuracy for these parameters. Compared with traditional loss functions, the new loss function reduces the maximum prediction error for equivalent electromagnetic parameters by 47%. This method significantly improves the prediction accuracy of SCS-Net for measured data, with a maximum improvement of 23.88%. These findings demonstrate that the proposed method enables precise SE prediction and design for composite structures while reducing the number of test samples needed.
基金the financial support of the National Natural Science Foundation of China(NSFC,No.12074093)。
文摘This study presents a novel approach to enhance silicon anode performance through barium titanate(BTO)incorporation,with the establishment of a force-electric coupling model.By introducing piezoelectric BTO into silicon matrices,we successfully improved both the mechanical stability and electrochemical kinetics of the anode.The developed force-electric coupling model explains how BTO mitigates stress accumulation during lithiation while optimizing the kinetics of Li^(+)and electron transfer.Experimental verification and multiphysical simulation indicate that Si@BTO effectively eliminates structural degradation during the cycling process and significantly reduces the charge transfer resistance.The force-electric coupling mechanism further facilitates stable solid electrolyte interphase(SEI)formation.When paired with LiFePO_(4)cathodes,Si@BTO maintains 76% capacity retention after 500 cycles at a 10 C rate.This work establishes a basic force-electric coupling model framework and offers insights into the development of advanced silicon anode batteries with exceptional performance.
文摘Materials engineering plays a key role in the field of electrochemical energy storage,and considerable efforts have been made in recent years to fulfill the future requirements of electrochemical energy storage using novel functional electrode materials.Materials with hollow structures are of particular interests due to their low density,large specific surface area and high porosity,making them promising candidates for energy conversion and storage.The Kirkendall effect has been widely applied for the synthesis of nanoscale hollow structures,which involves an unbalanced counter diffusion through a reaction interface.Herein,the recent progress on the use of the nanoscale Kirkendall effect to synthesize hollow nanostructures,including nanoparticles,one-dimensional(1-D),two-dimensional(2-D),and three-dimensional(3-D)nanostructures,and their potential applications in energy storage devices are summarized and discussed.And prospects is made for the future development of this research field.
文摘A conventional solid-state process was used to synthesize the double perovskite materials HoRCoMnO_(6)(R=Ho,Gd,Eu,Nd).The structural properties of the compounds were investigated using X-ray powder diffraction(XRD).The results revealed that Ho_(2)CoMnO_(6) crystallizes in a monoclinic structure with the P2_(1)/n space group.In contrast,the other compounds HoRCoMnO_(6)(R=Gd,Eu,or Nd) exhibit an orthorhombic structure with the Pnma space group.As a result,the average crystallite size also changes as a function of rare-earth element doping.This investigation reveals that the magnetic properties of the compounds studied are significantly dependent on the doping elements.The Curie temperature T_C,for example,increases from 80 to 118℃ with the ionic radii of rare earths increasing.Furthermore,the study of the magnetocaloric effect(MCE) shows that the maximum of the entropy variation(-ΔS_(M)^(max)) increases from 4.97 to 6.06 J/(kg·K) under a magnetic field of 5 T with substitution by rare-earth ions.To examine the efficiency of MCE materials,the relative cooling power(RCP) was evaluated and is found to increase with increment of rare-earth radius till 406.69 J/kg for Nd.The mean entropy variation with tempe rature(TEC) was also studied.Due to their significant magnetocaloric performance,HoRCoMnO_(6)(noted as HRCMO) compounds(with R=Ho,Gd,Eu or Nd) could be good candidates for low-temperature magnetic cooling applications.
基金supported by the National Major Scientific Instruments and Equipment Development Projects of China(No.41827808)the Major Program of the National Natural Science Foundation of China(No.42090055)Supported by Science and Technology Projects of Xizang Autonomous Region,China(No.XZ202402ZD0001)。
文摘In 2018,Baige,Xizang,witnessed two consecutive large-scale landslides,causing significant damage and drawing widespread attention.From March 2011 to February 2018,the Baige landslide exhibited a 50-m displacement without complete failure,culminating in a collapse in October 2018.The mechanisms behind its resistance to failure despite substantial deformation and the influence of the complex geo-structure within the tectonic mélange belt remain unclear.To address these questions,this study utilized a multidisciplinary approach,integrating on-site geological field mapping,surface deformation monitoring,multielectrode resistivity method,and deep displacement analysis.The aim was to evaluate the impact of the intricate geo-structure within the tectonic mélange belt on the Baige landslide events.Findings reveal that the landslide's geo-structure consists of structurally fractured,mesh-like rock masses,including heterogeneous lenticular rock masses and intermittent brittle shear zones distributed around the lens-shaped rock masses.The study underscores that the inhomogeneous and weakly deformed lenticular rock masses function as natural locked segments,governing the stability of the Baige landslide.Specifically,the relatively intact and hard granodiorite porphyry play a crucial role in locking the landslide's deformation.Deep displacement analysis indicates that the brittle shear zones act as the sliding surfaces.The progressive destruction of the locked segments and the gradual penetration of brittle shear zones,driven by gravitational potential energy,contribute to the landslide occurrence.This research provides critical insights into the formation mechanisms of large-scale landslides within tectonic mélange belts.
基金Under the auspices of National Natural Science Foundation of China(No.42171230)。
文摘Exploring carbon emission effects based on the evolution of residents’ dietary structure to achieve the carbon neutrality goal and mitigate climate change is an important task.This study took China as the research object(data excluding Hong Kong,Macao and Taiwan) and used the carbon emission coefficient method to quantitatively measure the food carbon emissions from 1987–2020,then analyzed the carbon emission effects under the evolution of dietary structure.The results showed that during the study period,the Chinese dietary structure gradually changed to a high-carbon consumption pattern.The dietary structure of urban residents developed to a balanced one,while that of rural residents developed to a high-quality one.During the study period,the per capita food carbon emissions and total food consumption of Chinese showed an increasing trend.The per capita food carbon emissions of residents in urban and rural showed an overall upward trend.The total food carbon emissions in urban increased significantly,while that in rural increased first and then decreased.The influence of beef and mutton on carbon emissions is the highest in dietary structure.Compared with the balanced dietary pattern,the food carbon emissions of Chinese residents had not yet reached the peak,but were evolving to a high-carbon consumption pattern.
基金co-supported by the National Natural Science Foundation of China(No.52105316)the National Natural Foundation of Jiangxi,China(No.2021BAB214046)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.501LKQB2022107021)Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(No.YESS20200397)。
文摘The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its application.To achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution process.Microstructural evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension tests.The findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing seam.The effects of grain size,such as pinning and splitting,are amplified at higher brazing temperatures.Additionally,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture mode.The fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack path.Therefore,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.
基金This work is financed by the grants of the National Natural Science Foundation of China （Grant No 40272084, 40472101 and 40572123）.
文摘The MohroCoulomb criterion has been widely used to explain formation of fractures. However, it fails to explain large strain deformation that widely occurs in nature. There is presently a new theory, the MEMC, which is mathematically expressed as Meff = （（σ1-σ3） L.sin 2α sin α）/2, where σ1-σ3 represents the yield strength of the related rock, L is a unit length and a is the angle between σ1 and deformation bands. This criterion demonstrates that the maximum value appears at angles of ±54.7° to σ1 and there is a slight difference in the moment in the range of 55°±10°. The range covers the whole observations available from nature and experiments. Its major implications include： （1） it can be used to determine the stress state when the related deformation features formed; （2） it provides a new approach to determine the Wk of the related ductile shear zone if only the ratio of the vorticity and strain rate remains fixed; （3） It can be used to explain （a） the obtuse angle in the contraction direction of conjugate kink-bands and extensional crenulation cleavages, （b） formation of low-angle normal faults and high-angle reverse faults, （c） lozenge ductile shear zones in basement terranes, （d） some crocodile structures in seismic profiles and （e） detachment folds in foreland basins.
基金financially supported by the Key Projects of the National Research and Development Program of China(2018YFD0400204)。
文摘In this study,Tremella fuciformis residues as raw material,dietary fibers from tremella were prepared by multiple enzymes.The structure of dietary fibers from tremella was studied by Fourier transform infrared(FTIR),X-ray diffraction analysis(XRD)and scanning electron microscopy(SEM).We analyzed their lipidlowering properties in vitro(water holding,oil holding swelling cholesterol and sodium cholate binding capacitises)and the hypolipidemic effects in mice.The results showed that tremella dietary fibers presented the infrared absorption spectrum characteristics of polysaccharides and the characteristic diffraction peaks of cellulose type I.SEM results indicated that the surface of insoluble dietary fiber(IDF)was porous,while the soluble dietary fiber(SDF)was relatively compact and spongy.IDF exhibited significantly higher water holding,oil holding,and swelling binding capacities than the corresponding SDF.However,SDF exhibited significantly higher viscosity than IDF.The results showed tremella dietary fibers were significant in swelling,water holding and oil holding,cholesterol and bile acids.In vivo experiment results in mice indicated that SDF has the best effect on hyperlipidemia mice than IDF and total dietary fiber(TDF).SDF showed that the total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)contents dropped by 28.33%,18.65%,and 48.97%,respectively,while high density lipoprotein cholesterol(HDL-C)content increased by 43.80%.Compared with the high-fat control(HCM)group,the arteriosclerosis index(AI)and liver index(LI)of the SDF group mice showed significant differences,indicating that SDF has a good auxiliary effect of lowering blood lipids.The administration of tremella fibers improved the lipid metabolism disorderly situation of hyperlipidemia mice.These results provide a reference for further research and rational development of T.fuciformis.
基金the Science and Technology Project of Xiamen Medical College(K2016-36).
文摘A water-soluble polysaccharide,designated BFP-3,was isolated from Bangia fuscopurpurea by hot water extraction,anion-exchange,and size-exclusion chromatography and tested to determine its antitumor activity.The structural characteristics of BFP-3 were investigated by chemical and spectroscopic methods,including partial acid hydrolysis,methylation analysis,one-and two-dimensional nuclear magnetic resonance,and gas chromatography-mass spectrometry.The results showed that BFP-3 was mainly comprised of rhamnose,arabinose,mannose,glucose,and galactose.Moreover,the weight-average molecular weight of BFP-3 was estimated to be approximately 333 kDa.The backbone of BFP-3 was primarily composed of repeating 5-α-l-Araf-1→(4-α-d-Glcp-1)_(4)→4,6-β-d-Manp-1 units,and the side chains consisted of repeatingβ-d-Galp-1→(4-β-d-Galp-1)_(4)→4,6-β-d-Galp-1→3,4-α-l-Rhap,β-l-Arap-1→(3-β-d-Galp-1)_(3),andβ-l-Arap-1 units.Counting Kit-8 assays revealed that BFP-3 significantly inhibited the proliferation of A2780,COC1,SKOV3,HO-8910,and OVCAR3 ovarian cancer cells in vitro,indicating that BFP-3 could have potential applications in the treatment of ovarian cancer.
文摘Ions or molecules are said to be isoelectronic if they are composed of different elements but have the same number of electrons, the same number of covalent bonds and the same structure. This criterion is unfortunately not sufficient to ensure that a chemical structure is a valid chemical compound. In a previous article, a procedure has been described to draw 2D valid structural formulas: the even-odd rule. This rule has been applied first to single-bonded molecules then to single-charged single-bonded ions. It covers hypovalent, hypervalent or classic Lewis’ octet compounds. The funding principle of the even-odd rule is that each atom of the compound possesses an outer-shell filled only with pairs of electrons. The application of this rule guarantees validity of any single-covalent-bond chemical structure. In the present paper, this even-odd rule and its electron-pair criterion are checked for coherence with an effective-valence isoelectronic rule using numerous known compounds having single-covalent-bond connections. The test addresses Lewis’ octet ions or molecules as well as hypovalent and hypervalent compounds. The article concludes that the even-odd rule and the effective-valence isoelectronicity rule are coherent for known single-covalent-bond chemical compounds.
文摘We designed a clamping device to study lateral photovoltaic effect (LPE) in Ni-SiO_(2)-Si structure with bias due to the appropriate barrier height.The LPE has a prominent sensitivity and linearity with 532 nm wavelength laser.The transient response time is 450μs and the relaxation time is 2 250μs in the Ni-SiO_(2)-Si structure without bias.The LPE sensitivity has a significant improvement with bias.The transient response time is 6μs and the relaxion time is 47μs with-7 V bias,not only improving the LPE sensitivity,but also increasing the response speed with bias.The research shows that the Schottky barrier structure can improve the sensitivity and linearity of LPE with bias effectively,and thus it can be used in position sensitive sensors.
基金Project support by the National Natural Science Foundation of China(Grant Nos.11704044 and 12074140)。
文摘The first-principles calculations are performed to examine structural,mechanical,and electronic properties at large strain for a monolayer C_(4)N_(4),which has been predicted as an anchoring promising material to attenuate shuttle effect in Li–S batteries stemming from its large absorption energy and low diffusion energy barrier.Our results show that the ideal strengths of C_(4)N_(4)under tension and pure shear deformation conditions reach 13.9 GPa and 12.5 GPa when the strains are 0.07 and 0.28,respectively.The folded five-membered rings and diverse bonding modes between carbon and nitrogen atoms enhance the ability to resist plastic deformation of C_(4)N_(4).The orderly bond-rearranging behaviors under the weak tensile loading path along the[100]direction cause the impressive semiconductor–metal transition and inverse semiconductor–metal transition.The present results enrich the knowledge of the structure and electronic properties of C_(4)N_(4)under deformations and shed light on exploring other two-dimensional materials under diverse loading conditions.
基金supported by the National Natural Science Foundation of China(Nos.12175199,U2267205,12475124)the ZSTU intramural grant(22062267-Y)。
文摘Understanding the properties of nuclei near the double magic nucleus^(40)Ca is crucial for both nuclear theory and experiments.In this study,Ca isotopes were investigated using an extended pairing-plus-quadrupole model with monopole corrections.The negative-parity states of^(44)Ca were coupled with the intruder orbital g_(9/2)at 4 MeV.The values of E_(4+)/E_(2+)agree well with experimental trend from^(42)Ca to^(50)Ca,considering monopole effects between νf_(7/2)and νp_(3/2)(νf_(5/2)).This monopole effect,determined from data of^(48)Ca and^(50)Ca,supports the proposed new nuclear magic number N=34 by predicting a high-energy 2^(+)state in^(54)Ca.
基金supported by the National Natural Science Foundation of China(Nos.22178047 and 21878042)the Dalian Science and Technology Innovation Fund(No.2020JJ26GX046)the Fundamental Research Funds for the Central Universities(Nos.DUT22LAB610 and DUT2022TB10)。
文摘Structural colors originated from Mie scattering of dielectric spheres can be regulated by the coupling effect between them and substrates.Here a rapid visual identification method of silver ornaments was proposed by the coupling effect of Zn O spheres with them.Both simulation and experimental results proved that,by coupling with different metal substrates,the Mie resonance scattering peaks of ZnO spheres with dimeter of 700 nm showed different degrees of redshift,which lead to different structural color appeared when ZnO spheres deposited on different metal surfaces with a similar appearance.A red structural color was displayed on the surface of the real silver ornament and a yellow-green structural color was shown on the surface of the cupronickel ornament.This method is quite simple and low-cost because it only needs to spray the dispersion of ZnO spheres on the ornament surface.Due to the mild chemical properties of the ZnO,covering and erasing ZnO spheres on the surface of silver would not corrode the silver ornament.Finally,an atomizer method was used for portable and daily testing.This work opens new perspectives on the visual identification of silver.
基金Project supported by the International Partnership Program of the Chinese Academy of Sciences(Grant No.123GJHZ2022035MI)the Fundamental Research Funds for the Central Universities(Grant Nos.WK3510000015 and WK3510000012)。
文摘Organic–inorganic lead halide perovskites(LHPs) have attracted great interest owing to their outstanding optoelectronic properties.Typically,the underlying electronic structure would determinate the physical properties of materials.But as for now,limited studies have been done to reveal the underlying electronic structure of this material system,comparing to the huge amount of investigations on the material synthesis.The effective mass of the valance band is one of the most important physical parameters which plays a dominant role in charge transport and photovoltaic phenomena.In pristine CsPbBr_(3),the Fr?hlich polarons associated with the Pb–Br stretching modes are proposed to be responsible for the effective mass renormalization.In this regard,it would be very interesting to explore the electronic structure in doped LHPs.Here,we report high-resolution angle-resolved photoemission spectroscopy(ARPES) studies on both pristine and Cl-doped CsPbBr_(3).The experimental band dispersions are extracted from ARPES spectra along both ■ and ■ high symmetry directions.DFT calculations are performed and directly compared with the ARPES data.Our results have revealed the band structure of Cl-doped CsPbBr_(3) for the first time,which have also unveiled the effective mass renormalization in the Cl-doped CsPbBr_(3) compound.Doping dependent measurements indicate that the chlorine doping could moderately tune the renormalization strength.These results will help understand the physical properties of LHPs as a function of doping.
基金supported by the Natural Science Foundation of China(grant No.71173174)
文摘Based on the survey data of typical villages in Shaanxi Province,China,the effect of social capital on the income gap of farmers' households was analyzed using the Shapley value of the total amount of social capital and the social capital structure.The results show the following:first,social capital can expand the household income gap,and the effect of this index on the household income gap is 7.54%.Second,the indexes of the social capital dimension can expand the household income gap,and the structural effects of the household income gap on social networks,social trust,and social participation are 3.17%,3.64%,and 0.65%,respectively.Third,no dimension of the path is the same as the effect on the household income gap.
基金supported by the National Natural Science Foundation of China(No.21771043,51572050 and 21601038)Guangxi Natural Science Foundation(No.2015GXNSFDA139007 and 2016GXNSFAA380085)Guangxi Key Laboratory of Electrochemical and Magnetochemical Functional Materials(EMFM20162107)
文摘2-（2,3-Dihydroxpropyliminomethyl）6-methoxyphenol（H3L）, trimethylacetic acid（Hpiv）, Gd（NO3）3·6 H2O and Co（NO3）2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2（L）2（μ3-OH）2（piv）6]·2 Hpiv·2 CH3OH（1）. X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798（6）, b = 12.0877（5）, c = 15.0367（7） ?, α = 67.320（4）°, β = 81.583（4）°, γ = 75.201（4）°, V =1939.62（18） ?3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ（I）. In magnetization study, heterometallic 1 exhibits magnetocaloric effect（MCE） of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.
基金supported by the National Natural Science Foundation of China(Grant Nos.42027806 and 42041006)。
文摘The size of pores or the grille spacing of water–sediment separation structures directly affects their regulation effect on the debris flow performance.A suitable pore size or grille spacing can effectively improve the water–sediment separation ability of the structure.The new funnel-type grating water–sediment separation structure(FGWSS)combines vertical and horizontal structures and provides a satisfactory water–sediment separation effect.However,the regulation effect of the grille spacing of the structure on the debris flow performance has not been studied.The regulation effect of the structure grille spacing on the debris flow performance is studied through a flume test,and the optimal structure grille spacing is obtained.An empirical equation of the relationship between the relative grille spacing of the structure and the sediment separation rate is established.Finally,the influence of the water–sediment separation structure on the regulation effect of debris flows is examined from two aspects:external factors(properties of debris flows)and internal factors(structural factors).The experimental results show that the gradation characteristics of solid particles in debris flows constitute a key factor affecting the regulation effect of the structure on the debris flow performance.The optimum grille spacing of the FGWSS matches the particle size corresponding to the material distribution curves d85~d90 of the debris flow.The total separation rate of debris flow particles is related to the grille spacing of the structure and the content of coarse and fine particles in the debris flow.
