The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-...The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-heterostructured nanoporous CoFe/CoFe_(2)O_(4) and CeO_(2−x),in situ grown on nickel foam(NF),holds great promise as a high-efficient bifunctional electrocatalyst(named R-CoFe/Ce/NF)for water splitting.Experimental characterization verifies surface reconstruction from CoFe alloy/oxide to highly active CoFeOOH during in situ electrochemical polarization.By virtues of three-dimensional nanoporous architecture and abundant electroactive CoFeOOH/CeO_(2−x) heterostructure interfaces,the R-CoFe/Ce/NF electrode achieves low overpotentials for oxygen evolution(η_(10)=227 mV;η_(500)=450 mV)and hydrogen evolution(η_(10)=35 mV;η_(408)=560 mV)reactions with high normalized electrochemical active surface areas,respectively.Additionally,the alkaline full water splitting electrolyzer of R-CoFe/Ce/NF||R-CoFe/Ce/NF achieves a current density of 50 mA·cm^(−2) only at 1.75 V;the decline of activity is satisfactory after 100-h durability test at 300 mA·cm^(−2).Density functional theory also demonstrates that the electron can transfer from CeO_(2−x) by virtue of O atom to CoFeOOH at CoFeOOH/CeO_(2−x) heterointerfaces and enhancing the adsorption of reactant,thus optimizing electronic structure and Gibbs free energies for the improvement of the activity for water splitting.展开更多
By adopting stochastic density functional theory(SDFT)and mixed stochastic-deterministic density functional theory(MDFT)methods,we perform first-principles calculations to predict the shock Hugoniot curves of boron(pr...By adopting stochastic density functional theory(SDFT)and mixed stochastic-deterministic density functional theory(MDFT)methods,we perform first-principles calculations to predict the shock Hugoniot curves of boron(pressure P=7.9×10^(3)-1.6×10^(6) GPa and temperature T=25-2800 eV),silicon(P=2.6×10^(3)-7.9×10^(5) GPa and T=21.5-1393 eV),and aluminum(P=5.2×10^(3)-9.0×10^(5) GPa and T=25-1393 eV)over wide ranges of pressure and temperature.In particular,we systematically investigate the impact of different cutoff radii in norm-conserving pseudopotentials on the calculated properties at elevated temperatures,such as pressure,ionization energy,and equation of state.By comparing the SDFT and MDFT results with those of other first-principles methods,such as extended first-principles molecular dynamics and path integral Monte Carlo methods,we find that the SDFT and MDFT methods show satisfactory precision,which advances our understanding of first-principles methods when applied to studies of matter at extremely high pressures and temperatures.展开更多
Bioprinting of cell-laden hydrogels is a rapidly growing field in tissue engineering.The advent of digital light processing(DLP)three-dimensional(3D)bioprinting technique has revolutionized the fabrication of complex ...Bioprinting of cell-laden hydrogels is a rapidly growing field in tissue engineering.The advent of digital light processing(DLP)three-dimensional(3D)bioprinting technique has revolutionized the fabrication of complex 3D structures.By adjusting light exposure,it becomes possible to control the mechanical properties of the structure,a critical factor in modulating cell activities.To better mimic cell densities in real tissues,recent progress has been made in achieving high-cell-density(HCD)printing with high resolution.However,regulating the stiffness in HCD constructs remains challenging.The large volume of cells greatly affects the light-based DLP bioprinting by causing light absorption,reflection,and scattering.Here,we introduce a neural network-based machine learning technique to predict the stiffness of cell-laden hydrogel scaffolds.Using comprehensive mechanical testing data from 3D bioprinted samples,the model was trained to deliver accurate predictions.To address the demand of working with precious and costly cell types,we employed various methods to ensure the generalizability of the model,even with limited datasets.We demonstrated a transfer learning method to achieve good performance for a precious cell type with a reduced amount of data.The chosen method outperformed many other machine learning techniques,offering a reliable and efficient solution for stiffness prediction in cell-laden scaffolds.This breakthrough paves the way for the next generation of precision bioprinting and more customized tissue engineering.展开更多
To address the issues of unknown target size,blurred edges,background interference and low contrast in infrared small target detection,this paper proposes a method based on density peaks searching and weighted multi-f...To address the issues of unknown target size,blurred edges,background interference and low contrast in infrared small target detection,this paper proposes a method based on density peaks searching and weighted multi-feature local difference.Firstly,an improved high-boost filter is used for preprocessing to eliminate background clutter and high-brightness interference,thereby increasing the probability of capturing real targets in the density peak search.Secondly,a triple-layer window is used to extract features from the area surrounding candidate targets,addressing the uncertainty of small target sizes.By calculating multi-feature local differences between the triple-layer windows,the problems of blurred target edges and low contrast are resolved.To balance the contribution of different features,intra-class distance is used to calculate weights,achieving weighted fusion of multi-feature local differences to obtain the weighted multi-feature local differences of candidate targets.The real targets are then extracted using the interquartile range.Experiments on datasets such as SIRST and IRSTD-IK show that the proposed method is suitable for various complex types and demonstrates good robustness and detection performance.展开更多
Electrically assisted forming(EAF)is a reliable method of reducing the deformation resistance of metallic materials and enhancing their formability.In this study,the mechanical properties and microstructure of Al_(0.5...Electrically assisted forming(EAF)is a reliable method of reducing the deformation resistance of metallic materials and enhancing their formability.In this study,the mechanical properties and microstructure of Al_(0.5)CoCrFeNi high-entropy alloy(HEA)under electrically assisted compression(EAC)were investigated.The results showed that the flow stress decreased with increasing current density in the EAC.Specifically,the flow curves exhibited S-shaped softening at a higher current density,which was dominated by the non-uniform distribution of the Joule heating temperature during EAC.When the flow stress was fixed at 500 MPa and 80 A·mm^(−2),compressible deformation amounts of 63.7%were observed at a strain rate of 1 s−1,indicating full compression of Al_(0.5)CoCrFeNi HEA at low-stress levels.Based on the microstructure,the flowability of Al_(0.5)CoCrFeNi HEA was improved during EAC,and the flow direction shifted from 45°to the horizontal direction.The current density,which influences the Joule heating temperature and strain rate,synergistically affects the stacking fault energy(SFE)and critical resolved shear stress(CRSS),which affect the tendency for twinning behavior.Thererfore,deformation nanoscale twins(DTs)were observed,indicating a shift in the deformation mechanisms from dislocation slip domination to a mixed pattern of dislocation slip and twinning.This study confirmed the deformability of Al_(0.5)CoCrFeNi HEA during EAC and provided an experimental foundation and theoretical support for the formation of HEAs.展开更多
The large current density of electrochemical CO_(2)reduction towards industrial application is challenging.Herein,without strong acid and reductant,the synthesized BiVO_(4)with abundant oxygen vacancies(Ovs)exhibited ...The large current density of electrochemical CO_(2)reduction towards industrial application is challenging.Herein,without strong acid and reductant,the synthesized BiVO_(4)with abundant oxygen vacancies(Ovs)exhibited a high formate Faradaic efficiency(FE)of 97.45%(-0.9 V)and a large partial current density of-45.82 mA/cm^(2)(-1.2 V).The good performance benefits from the reconstruction of BiVO_(4)to generate active metal Bi sites,which results in the electron redistribution to boost the OCHO∗formation.In flow cells,near industrial current density of 183.94 mA/cm^(2)was achieved,with the FE of formate above 95%from 20mA/cm^(2)to 180mA/cm^(2).Our work provides a facily synthesized BiVO_(4)precatalyst for CO_(2)electroreduction.展开更多
AIM:To assess the variations in photoreceptor cell packing density(PCPD)across the retina among young healthy individuals with emmetropia,low and moderate myopia.METHODS:High-resolution adaptive optics scanning laser ...AIM:To assess the variations in photoreceptor cell packing density(PCPD)across the retina among young healthy individuals with emmetropia,low and moderate myopia.METHODS:High-resolution adaptive optics scanning laser ophthalmoscopy(AOSLO)systems were utilized for retinal imaging with a large sampling window of 700μm×700μm.The study cohort included 14 emmetropic[spherical equivalent(SE)ranged+0.5 to-0.5 D],15 low myopic(SE ranged-0.5 to-3 D)and 21 moderate myopic(SE ranged-3 to-6 D)healthy young adults.Photoreceptors at 3°temporal,6°superior and inferior 6°were captured.Statistical analysis was then performed to obtain PCPD and cell spacing.RESULTS:The average age of participants was 22.54±2.86(ranged 20–30y)with no difference among 3 groups.At 3°temporal,the emmetropic group exhibited the highest PCPD of 15186.16±2050.54 cells/mm^(2),while the low and moderate myopic groups had PCPD of 14009.15±1073.01 and 13466.92±1121.71 cells/mm2,respectively.At 3°temporal,the emmetropic group also had the smallest cell spacing at 6.66±0.26 mm,compared to 6.85±0.26 and 6.91±0.28 mm for the low and moderate myopic groups,respectively.Compared to the emmetropic group,at 3°temporal,the myopic groups showed significantly reduced PCPD(low myopia:P=0.032;moderate myopia:P=0.001).At 6°inferior,the moderate myopic group exhibited a significant decrease in PCPD(P=0.013),while at 6°superior,there were no significant statistical differences in PCPD for the low and moderate myopic groups(P>0.05).In comparison to the emmetropic group,only the moderate myopic group showed significantly increased cell spacing at all three positions(temporal 3°:P=0.011,superior 6°:P=0.046,inferior 6°:P=0.013).Correlation analysis revealed a positive correlation between PCPD and axial length changes(P<0.05).CONCLUSION:Reduced PCPD and increased cell spacing strongly correlated with refractive error in mild to moderate myopic eyes,especially at 6°inferior to the fovea and the decreased PCPD in the macular region of myopic patients may be associated with increased axial lengthinduced retinal stretching.展开更多
In this study,a novel cost-effective methodology was developed to enhance the gas barrier properties and permselectivity of unfilled natural rubber(NR)/polybutadiene rubber(BR)composites through the construction of a ...In this study,a novel cost-effective methodology was developed to enhance the gas barrier properties and permselectivity of unfilled natural rubber(NR)/polybutadiene rubber(BR)composites through the construction of a heterogeneous structure using pre-vulcanized powder rubber to replace traditional fillers.The matrix material is composed of a blend of NR and BR,which is widely used in tire manufacturing.By incorporating pre-vulcanized trans-1,4-poly(isoprene-co-butadiene)(TBIR)rubber powder(pVTPR)with different cross-linking densities and contents,significant improvements in the gas barrier properties and CO_(2)permselectivity of the NR/BR/pVTPR composites were observed.The results indicated that compared to NR/BR/TBIR composites prepared through direct blending of NR,BR,and TBIR,the NR/BR/pVTPR composites exhibited markedly superior gas barrier properties.Increasing the cross-linking density of pVTPR resulted in progressive enhancement of the gas barrier properties of the NR/BR/pVTPR composite.For example,the addition of 20 phr pVTPR with a cross-linking density of 346 mol/m^(3)resulted in a 79%improvement in the oxygen barrier property of NR/BR/pVTPR compared to NR/BR,achieving a value of 5.47×10^(-14)cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1).Similarly,the nitrogen barrier property improved by 76%compared to NR/BR,reaching 2.4×10^(-14)cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1),which is 28%higher than the conventional inner liner material brominated butyl rubber(BIIR,PN2=3.32×10^(-14)cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1)).Owing to its low cost,exceptional gas barrier properties,superior adhesion to various tire components,and co-vulcanization capabilities,the NR/BR/pVTPR composite has emerged as a promising alternative to butyl rubber in the inner liner of tires.Furthermore,by fine-tuning the cross-linking density of pVTPR,the high-gas-barrier NR/BR/pVTPR composites also demonstrated remarkable CO_(2)permselectivity,with a CO_(2)/N2 selectivity of 61.4 and a CO_(2)/O_(2)selectivity of 26.12.This innovation provides a novel strategy for CO_(2)capture and separation,with potential applications in future environmental and industrial processes.The multifunctional NR/BR/pVTPR composite,with its superior gas barrier properties and CO_(2)permselectivity,is expected to contribute to the development of safer,greener,and more cost-effective transportation solutions.展开更多
Lithium plating/stripping occurs at the a node/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase(SEI).The dua...Lithium plating/stripping occurs at the a node/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase(SEI).The dual continuous rapid transport of interfacial electron/ion is required for homogeneous Li deposition.Herein,we propose a strategy to improve the Li metal anode performance by rationally regulating the interfacial electron density and Li ion transport through the SEI film.This key technique involves decreasing the interfacial oxygen density of biomass-derived carbon host by regulating the arrangement of the celluloses precursor fibrils.The higher specific surface area and lower interfacial oxygen density decrease the local current density and ensure the formation of thin and even SEI film,which stabilized Li^(+)transfer through the Li/electrolyte interface.Moreover,the improved graphitization and the interconnected conducting network enhance the surface electronegativity of carbon and enable uninterruptible electron conduction.The result is continuous and rapid coupled interfacial electron/ion transport at the anode/electrolyte reaction interface,which facilitates uniform Li deposition and improves Li anode performance.The Li/C anode shows a high initial Coulombic efficiency of 98%and a long-term lifespan of over 150cycles at a practical low N/P(negative-to-positive)ratio of 1.44 in full cells.展开更多
The authors regret Acknowledgements Firstly,the authors wish to acknowledge the academic support from Ruhr University Bochum during the first author's(Xiao Yan)research stay from 2018.11 to 2020.10,including the s...The authors regret Acknowledgements Firstly,the authors wish to acknowledge the academic support from Ruhr University Bochum during the first author's(Xiao Yan)research stay from 2018.11 to 2020.10,including the soft code implement and debug support from Vladislav Gudzulic and academic advising from Günther Meschke.展开更多
The development of modern agriculture requires the reduction of water and chemical N fertilizer inputs.Increasing the planting density can maintain higher yields,but also consumes more of these restrictive resources.H...The development of modern agriculture requires the reduction of water and chemical N fertilizer inputs.Increasing the planting density can maintain higher yields,but also consumes more of these restrictive resources.However,whether an increased maize density can compensate for the negative effects of reduced water and N supply on grain yield and N uptake in the arid irrigated areas remains unknown.This study is part of a long-term positioning trial that started in 2016.A split-split plot field experiment of maize was implemented in the arid irrigated area of northwestern China in 2020 to 2021.The treatments included two irrigation levels:local conventional irrigation reduced by 20%(W1,3,240 m^(3)ha^(-1))and local conventional irrigation(W2,4,050 m^(3)ha^(-1));two N application rates:local conventional N reduced by 25%(N1,270 kg ha^(-1))and local conventional N(360 kg ha^(-1));and three planting densities:local conventional density(D1,75,000 plants ha^(-1)),density increased by 30%(D2,97,500 plants ha-1),and density increased by 60%(D3,120,000 plants ha^(-1)).Our results showed that the grain yield and aboveground N accumulation of maize were lower under the reduced water and N inputs,but increasing the maize density by 30% can compensate for the reductions of grain yield and aboveground N accumulation caused by the reduced water and N supply.When water was reduced while the N application rate remained unchanged,increasing the planting density by 30% enhanced grain yield by 13.9% and aboveground N accumulation by 15.3%.Under reduced water and N inputs,increasing the maize density by 30% enhanced N uptake efficiency and N partial factor productivity,and it also compensated for the N harvest index and N metabolic related enzyme activities.Compared with W2N2D1,the N uptake efficiency and N partial factor productivity increased by 28.6 and 17.6%under W1N1D2.W1N2D2 had 8.4% higher N uptake efficiency and 13.9% higher N partial factor productivity than W2N2D1.W1N2D2 improved urease activity and nitrate reductase activity by 5.4% at the R2(blister)stage and 19.6% at the V6(6th leaf)stage,and increased net income and the benefit:cost ratio by 22.1 and 16.7%,respectively.W1N1D2 and W1N2D2 reduced the nitrate nitrogen and ammoniacal nitrogen contents at the R6 stage in the 40-100 cm soil layer,compared with W2N2D1.In summary,increasing the planting density by 30% can compensate for the loss of grain yield and aboveground N accumulation under reduced water and N inputs.Meanwhile,increasing the maize density by 30% improved grain yield and aboveground N accumulation when water was reduced by 20% while the N application rate remained constant in arid irrigation areas.展开更多
To investigate the effect of saturation on the storage-dissipation properties and failure characteristics of red sandstone,as well as the energy mechanism of rockburst prevention by water,a series of uniaxial compress...To investigate the effect of saturation on the storage-dissipation properties and failure characteristics of red sandstone,as well as the energy mechanism of rockburst prevention by water,a series of uniaxial compression and uniaxial loading–unloading tests were conducted under five saturation levels.The effect of saturation on the mechanical properties and elastic energy density was analyzed,and a method for obtaining peak energy density was proposed.The effect of saturation on the energy evolution was examined,and the energy mechanism of water in preventing rockburst was revealed.The results indicate that an increase in saturation of red sandstone decreases the input energy density,elastic energy density,dissipated energy density,peak strength and peak strain;the compaction phase of the stress–strain curve becomes shorter;the failure mode transitions from X-conjugate oblique shear to single oblique shear;the variation in the debris ejection trajectory is as follows:radiation→X-ray→oblique upward parabola→horizontal parabola→oblique downward parabola;the degree of failure intensity and fragmentation is decreased gradually.Elastic energy density is interconnected with both saturation and stress but independent of the loading path.Saturation exhibits a dual effect on the energy storage property,i.e.,increasing saturation increases the energy storage efficiency and reduces the energy storage capacity.The ratio of peak elastic energy density to peak input energy density remains constant irrespective of saturation levels.Water prevents rockburst by decreasing the energy storage capacity of surrounding rock,alleviating the stress of surrounding rock to reduce energy storage,and elevating the energy release threshold of high-energy surrounding rock.The findings of this study contribute to understanding the effect of water on rock failure from an energy perspective,as well as provide theoretical guidance for rockburst prevention by water in deep tunnels.展开更多
Na_(3)V_(2)(PO_(4))_(3)(NVP)is gifted with fast Na^(+)conductive NASICON structure.But it still suffers from low electronic conductivity and inadequate energy density.Herein,a high-entropy modification strategy is rea...Na_(3)V_(2)(PO_(4))_(3)(NVP)is gifted with fast Na^(+)conductive NASICON structure.But it still suffers from low electronic conductivity and inadequate energy density.Herein,a high-entropy modification strategy is realized by doping V^(3+)site with Ga^(3+)/Cr^(3+)/Al^(3+)/Fe^(3+)/In^(3+)simultaneously(i.e.Na_(3)V_(2-x)(GaCrAlFeIn)_x(PO_(4))_(3);x=0,0.04,0.06,and 0.08)to stimulate the V^(5+)■V^(2+)reversible multi-electron redox.Such configuration high-entropy can effectively suppress the structural collapse,enhance the redox reversibility in high working voltage(4.0 V),and optimize the electronic induced effect.The in-situ X-ray powder diffraction and in-situ electrochemical impedance spectroscopy tests efficaciously confirm the robust structu ral recovery and far lower polarization throughout an entire charge-discharge cycle during 1.6-4.3 V,respectively.Moreover,the density functional theory calculations clarify the stronger metallicity of high-entropy electrode than the bare that is derived from the more mobile free electrons surrounding the vicinity of Fermi level.By grace of high-entropy design and multi-electron transfer reactions,the optimal Na_(3)V_(1.7)(GaCrAlFeIn)_(0.06)(PO_(4))_(3)can exhibit perfect cycling/rate performances(90.97%@5000 cycles@30 C;112 mA h g^(-1)@10 C and 109 mA h g^(-1)@30 C,2.0-4.3 V).Furthermore,it can supply ultra-high185 mA h g^(-1)capacity with fa ntastic energy density(522 W h kg^(-1))in half-cells(1.4-4.3 V),and competitive capacity(121 mA h g^(-1))as well as energy density(402 W h kg^(-1))in full-cells(1.6-4.1 V),demonstrating enormous application potential for sodium-ion batteries.展开更多
As primary degradation products of phthalate esters,phthalate monoesters(MPEs)have been widely detected in various aquatic environments and drawn growing toxicological concerns.Hydrolysis kinetics that is of importanc...As primary degradation products of phthalate esters,phthalate monoesters(MPEs)have been widely detected in various aquatic environments and drawn growing toxicological concerns.Hydrolysis kinetics that is of importance for assessing environmental persistence of chemicals remain elusive for MPEs.Herein,kinetics of base-catalyzed and neutral hydrolysis for 18 MPEs with different leaving groups was investigated by density functional theory calculation.Results indicate that MPEs with leaving groups having p Kaof<10 prefer dissociative transition states.MPEs are more persistent than their parents,and their hydrolysis half-lives were calculated to vary from 3.4 min to 79.2 years(p H=7–9).A quantitative structure-activity relationship model was developed for predicting the hydrolysis kinetics parameters.It was found that p Kaof the leaving groups and electronegativity of the MPEs are key factors determining the hydrolysis kinetics.This work may lay a theoretical foundation for better understanding the chemical process that governs MPE persistence in aquatic environments.展开更多
The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly co...The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors,yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability.Here,for the first time,an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate PPy-reduced graphene oxide/poly(vinylidene difluoride-cohexafluoropropylene)(PVDF-HFP)(PPy-rGO/PH)electrodes with controllable polymerization behavior and exceptional areal mass loading.The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition,achieving an impressive mass loading of 185.6 mg cm^(-2)(particularly 79.2 mg cm^(-2)for polypyrrole)and a superior areal capacitance of 25.2 F cm^(-2)at 2 mA cm^(-2)for a 12-layer electrode.In agreement with theses appealing features,an unprecedented areal energy density of 1.47 mW h cm^(-2)for a symmetrical device is registered,a rarely achieved value for other PPy/rGO-based supercapacitors.This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.展开更多
Density order is usually a consequence of the competition between long-range and short-range interactions.Here we report a density ordered superfluid emergent from a homogeneous Mott insulator due to the competition b...Density order is usually a consequence of the competition between long-range and short-range interactions.Here we report a density ordered superfluid emergent from a homogeneous Mott insulator due to the competition between frustrations and local interactions.This transition is found in a Bose–Hubbard model on a frustrated triangle lattice with an extra pairing term.Furthermore,we find a quantum phase transition between two different density ordered superfluids,which is beyond the Landau–Ginzburg(LG)paradigm.A U(1)symmetry is emergent at the critical point,while the symmetry in each density ordered superfluid is Z_(2)×Z_(3).We call the transition a‘shamrock transition’,due to its degenerate ground state in the parameter space being a shamrock-like curve rather than a circle in an LG-type transition.Effective low energy theories are established for the two transitions mentioned above and we find their resemblance and differences with clock models.展开更多
Fe-N-C catalysts are widely considered as promising non-precious-metal candidates for electrocatalytic oxygen reduction reaction(ORR),Yet despite their high catalytic activity through rational modulation,challenges re...Fe-N-C catalysts are widely considered as promising non-precious-metal candidates for electrocatalytic oxygen reduction reaction(ORR),Yet despite their high catalytic activity through rational modulation,challenges remain in their low site density and unsatisfactory mass transfer structure.Herein,we present a structural engineering approach employing a soft-template coating strategy to fabricate a hollow and hierarchically porous N-doped carbon framework anchored with atomically dispersed Fe sites(FeNCh) as an efficient ORR catalyst.The combination of hierarchical porosity and high exterior surface area is proven crucial for exposing more active sites,which gives rise to a remarkable ORR performance with a half-wave potential of 0.902 V in 0.1 m KOH and 0.814 V in 0.1 m HClO_(4),significantly outperforming its counterpart with solid structure and dominance of micropores(FeNC-s).The mass transfer property is revealed by in-situ electrochemical impedance spectroscopy(EIS) measurement.The distribution of relaxation time(DRT) analysis is further introduced to deconvolve the kinetic and mass transport processes,which demonstrates an alleviated mass transport resistance for FeNC-h,validating the effectiveness of structural engineering.This work not only provides an effective structural engineering approach but also contributes to the comprehensive mass transfer evaluation on advanced electrocatalyst for energy conversion applications.展开更多
A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies t...A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz condition.As a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s output.In this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic variables.Since pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is proposed.Furthermore,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output uncertainty.Based on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased estimation.Finally,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction method.The effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.展开更多
Dense cropping increases crop yield but intensifies resource competition,which reduces single plant yield and limits potential yield growth.Optimizing canopy spacing could enhance resource utilization,support crop mor...Dense cropping increases crop yield but intensifies resource competition,which reduces single plant yield and limits potential yield growth.Optimizing canopy spacing could enhance resource utilization,support crop morphological development and increase yield.Here,a three-year study was performed to verify the feasibility of adjusting row spacing to further enhance yield in densely planted soybeans.Of three row-spacing configurations(40-40,20-40,and 20-60 cm)and two planting densities(normal 180,000 plants ha 1 and high 270,000 plants ha 1).The differences in canopy structure,plant morphological development,photosynthetic capacity and their impact on yield were analyzed.Row spacing configurations have a significant effect on canopy transmittance(CT).The 20-60 cm row spacing configuration increased CT and creates a favorable canopy light environment,in which plant height is reduced,while branching is promoted.This approach reduces plant competition,optimizes the developments of leaf area per plant,specific leaf area,leaf area development rate,leaf area duration and photosynthetic physiological indices(F_(v)/F_(m),ETR,P_(n)).The significant increase of 11.9%-34.2%in canopy apparent photosynthesis(CAP)is attributed to the significant optimization of plant growth and photosynthetic physiology through CT,an important contributing factor to yield increases.The yield in the 20-60 cm treatment is 4.0%higher than in equidistant planting under normal planting density,but 5.9%under high density,primarily driven by CAP and pod number.These findings suggest that suitable row spacing configurations optimize the light environment for plants,promote source-sink transformation in soybeans,and further improve yield.In practice,a 20-60 cm row spacing configuration could be employed for high-density soybean planting to achieve a more substantial yield gain.展开更多
基金sponsored by the National Natural Science Foundation of China(Nos.5210125 and 52375422)the Science Research Project of Hebei Education Department(No.BJK2023058)the Natural Science Foundation of Hebei Province(Nos.E2020208069,B2020208083 and E202320801).
文摘The stability and electrocatalytic efficiency of transition metal oxides for water splitting is determined by geometric and electronic structure,especially under high current densities.Herein,a newly designed lamella-heterostructured nanoporous CoFe/CoFe_(2)O_(4) and CeO_(2−x),in situ grown on nickel foam(NF),holds great promise as a high-efficient bifunctional electrocatalyst(named R-CoFe/Ce/NF)for water splitting.Experimental characterization verifies surface reconstruction from CoFe alloy/oxide to highly active CoFeOOH during in situ electrochemical polarization.By virtues of three-dimensional nanoporous architecture and abundant electroactive CoFeOOH/CeO_(2−x) heterostructure interfaces,the R-CoFe/Ce/NF electrode achieves low overpotentials for oxygen evolution(η_(10)=227 mV;η_(500)=450 mV)and hydrogen evolution(η_(10)=35 mV;η_(408)=560 mV)reactions with high normalized electrochemical active surface areas,respectively.Additionally,the alkaline full water splitting electrolyzer of R-CoFe/Ce/NF||R-CoFe/Ce/NF achieves a current density of 50 mA·cm^(−2) only at 1.75 V;the decline of activity is satisfactory after 100-h durability test at 300 mA·cm^(−2).Density functional theory also demonstrates that the electron can transfer from CeO_(2−x) by virtue of O atom to CoFeOOH at CoFeOOH/CeO_(2−x) heterointerfaces and enhancing the adsorption of reactant,thus optimizing electronic structure and Gibbs free energies for the improvement of the activity for water splitting.
基金supported by the National Key R&D Program of China under Grant No.2025YFB3003603the National Natural Science Foundation of China under Grant Nos.12135002 and 12105209.
文摘By adopting stochastic density functional theory(SDFT)and mixed stochastic-deterministic density functional theory(MDFT)methods,we perform first-principles calculations to predict the shock Hugoniot curves of boron(pressure P=7.9×10^(3)-1.6×10^(6) GPa and temperature T=25-2800 eV),silicon(P=2.6×10^(3)-7.9×10^(5) GPa and T=21.5-1393 eV),and aluminum(P=5.2×10^(3)-9.0×10^(5) GPa and T=25-1393 eV)over wide ranges of pressure and temperature.In particular,we systematically investigate the impact of different cutoff radii in norm-conserving pseudopotentials on the calculated properties at elevated temperatures,such as pressure,ionization energy,and equation of state.By comparing the SDFT and MDFT results with those of other first-principles methods,such as extended first-principles molecular dynamics and path integral Monte Carlo methods,we find that the SDFT and MDFT methods show satisfactory precision,which advances our understanding of first-principles methods when applied to studies of matter at extremely high pressures and temperatures.
基金supported in part by the National Institutes of Health(Nos.R01HD112026 and R21ES034455)National Science Foundation(NSF,Nos.2135720 and 2223669)performed at San Diego Nanotechnology Infrastructure(SDNI)of UCSD,a member of the National Nanotechnology Coordinated Infrastructure(NNCI),which is supported by NSF(Grant No.ECCS-2025752).
文摘Bioprinting of cell-laden hydrogels is a rapidly growing field in tissue engineering.The advent of digital light processing(DLP)three-dimensional(3D)bioprinting technique has revolutionized the fabrication of complex 3D structures.By adjusting light exposure,it becomes possible to control the mechanical properties of the structure,a critical factor in modulating cell activities.To better mimic cell densities in real tissues,recent progress has been made in achieving high-cell-density(HCD)printing with high resolution.However,regulating the stiffness in HCD constructs remains challenging.The large volume of cells greatly affects the light-based DLP bioprinting by causing light absorption,reflection,and scattering.Here,we introduce a neural network-based machine learning technique to predict the stiffness of cell-laden hydrogel scaffolds.Using comprehensive mechanical testing data from 3D bioprinted samples,the model was trained to deliver accurate predictions.To address the demand of working with precious and costly cell types,we employed various methods to ensure the generalizability of the model,even with limited datasets.We demonstrated a transfer learning method to achieve good performance for a precious cell type with a reduced amount of data.The chosen method outperformed many other machine learning techniques,offering a reliable and efficient solution for stiffness prediction in cell-laden scaffolds.This breakthrough paves the way for the next generation of precision bioprinting and more customized tissue engineering.
基金supported by the National Natural Science Foundation of China (No.52205548)。
文摘To address the issues of unknown target size,blurred edges,background interference and low contrast in infrared small target detection,this paper proposes a method based on density peaks searching and weighted multi-feature local difference.Firstly,an improved high-boost filter is used for preprocessing to eliminate background clutter and high-brightness interference,thereby increasing the probability of capturing real targets in the density peak search.Secondly,a triple-layer window is used to extract features from the area surrounding candidate targets,addressing the uncertainty of small target sizes.By calculating multi-feature local differences between the triple-layer windows,the problems of blurred target edges and low contrast are resolved.To balance the contribution of different features,intra-class distance is used to calculate weights,achieving weighted fusion of multi-feature local differences to obtain the weighted multi-feature local differences of candidate targets.The real targets are then extracted using the interquartile range.Experiments on datasets such as SIRST and IRSTD-IK show that the proposed method is suitable for various complex types and demonstrates good robustness and detection performance.
基金supported by the National Natural Science Foundation of China(Nos.52305349,52305423 and 51635005)CGN-HIT Advanced Nuclear and New Energy Research Institute(No.CGN-HIT202305).
文摘Electrically assisted forming(EAF)is a reliable method of reducing the deformation resistance of metallic materials and enhancing their formability.In this study,the mechanical properties and microstructure of Al_(0.5)CoCrFeNi high-entropy alloy(HEA)under electrically assisted compression(EAC)were investigated.The results showed that the flow stress decreased with increasing current density in the EAC.Specifically,the flow curves exhibited S-shaped softening at a higher current density,which was dominated by the non-uniform distribution of the Joule heating temperature during EAC.When the flow stress was fixed at 500 MPa and 80 A·mm^(−2),compressible deformation amounts of 63.7%were observed at a strain rate of 1 s−1,indicating full compression of Al_(0.5)CoCrFeNi HEA at low-stress levels.Based on the microstructure,the flowability of Al_(0.5)CoCrFeNi HEA was improved during EAC,and the flow direction shifted from 45°to the horizontal direction.The current density,which influences the Joule heating temperature and strain rate,synergistically affects the stacking fault energy(SFE)and critical resolved shear stress(CRSS),which affect the tendency for twinning behavior.Thererfore,deformation nanoscale twins(DTs)were observed,indicating a shift in the deformation mechanisms from dislocation slip domination to a mixed pattern of dislocation slip and twinning.This study confirmed the deformability of Al_(0.5)CoCrFeNi HEA during EAC and provided an experimental foundation and theoretical support for the formation of HEAs.
基金financially supported by the Fundamental Research Funds for the Central Universities of Central South University(No.2022ZZTS0579).
文摘The large current density of electrochemical CO_(2)reduction towards industrial application is challenging.Herein,without strong acid and reductant,the synthesized BiVO_(4)with abundant oxygen vacancies(Ovs)exhibited a high formate Faradaic efficiency(FE)of 97.45%(-0.9 V)and a large partial current density of-45.82 mA/cm^(2)(-1.2 V).The good performance benefits from the reconstruction of BiVO_(4)to generate active metal Bi sites,which results in the electron redistribution to boost the OCHO∗formation.In flow cells,near industrial current density of 183.94 mA/cm^(2)was achieved,with the FE of formate above 95%from 20mA/cm^(2)to 180mA/cm^(2).Our work provides a facily synthesized BiVO_(4)precatalyst for CO_(2)electroreduction.
基金Supported by National Natural Science Foundation of China(No.82271107).
文摘AIM:To assess the variations in photoreceptor cell packing density(PCPD)across the retina among young healthy individuals with emmetropia,low and moderate myopia.METHODS:High-resolution adaptive optics scanning laser ophthalmoscopy(AOSLO)systems were utilized for retinal imaging with a large sampling window of 700μm×700μm.The study cohort included 14 emmetropic[spherical equivalent(SE)ranged+0.5 to-0.5 D],15 low myopic(SE ranged-0.5 to-3 D)and 21 moderate myopic(SE ranged-3 to-6 D)healthy young adults.Photoreceptors at 3°temporal,6°superior and inferior 6°were captured.Statistical analysis was then performed to obtain PCPD and cell spacing.RESULTS:The average age of participants was 22.54±2.86(ranged 20–30y)with no difference among 3 groups.At 3°temporal,the emmetropic group exhibited the highest PCPD of 15186.16±2050.54 cells/mm^(2),while the low and moderate myopic groups had PCPD of 14009.15±1073.01 and 13466.92±1121.71 cells/mm2,respectively.At 3°temporal,the emmetropic group also had the smallest cell spacing at 6.66±0.26 mm,compared to 6.85±0.26 and 6.91±0.28 mm for the low and moderate myopic groups,respectively.Compared to the emmetropic group,at 3°temporal,the myopic groups showed significantly reduced PCPD(low myopia:P=0.032;moderate myopia:P=0.001).At 6°inferior,the moderate myopic group exhibited a significant decrease in PCPD(P=0.013),while at 6°superior,there were no significant statistical differences in PCPD for the low and moderate myopic groups(P>0.05).In comparison to the emmetropic group,only the moderate myopic group showed significantly increased cell spacing at all three positions(temporal 3°:P=0.011,superior 6°:P=0.046,inferior 6°:P=0.013).Correlation analysis revealed a positive correlation between PCPD and axial length changes(P<0.05).CONCLUSION:Reduced PCPD and increased cell spacing strongly correlated with refractive error in mild to moderate myopic eyes,especially at 6°inferior to the fovea and the decreased PCPD in the macular region of myopic patients may be associated with increased axial lengthinduced retinal stretching.
基金supported by the National Key Research and Development Program of China (No. 2022YFB3704700(2022YFB3704702))the National Natural Science Foundation of China (No. 52473096)+1 种基金Major Scientific and Technological Innovation Project of Shandong Province (No. 2021CXGC010901)Taishan Scholar Program
文摘In this study,a novel cost-effective methodology was developed to enhance the gas barrier properties and permselectivity of unfilled natural rubber(NR)/polybutadiene rubber(BR)composites through the construction of a heterogeneous structure using pre-vulcanized powder rubber to replace traditional fillers.The matrix material is composed of a blend of NR and BR,which is widely used in tire manufacturing.By incorporating pre-vulcanized trans-1,4-poly(isoprene-co-butadiene)(TBIR)rubber powder(pVTPR)with different cross-linking densities and contents,significant improvements in the gas barrier properties and CO_(2)permselectivity of the NR/BR/pVTPR composites were observed.The results indicated that compared to NR/BR/TBIR composites prepared through direct blending of NR,BR,and TBIR,the NR/BR/pVTPR composites exhibited markedly superior gas barrier properties.Increasing the cross-linking density of pVTPR resulted in progressive enhancement of the gas barrier properties of the NR/BR/pVTPR composite.For example,the addition of 20 phr pVTPR with a cross-linking density of 346 mol/m^(3)resulted in a 79%improvement in the oxygen barrier property of NR/BR/pVTPR compared to NR/BR,achieving a value of 5.47×10^(-14)cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1).Similarly,the nitrogen barrier property improved by 76%compared to NR/BR,reaching 2.4×10^(-14)cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1),which is 28%higher than the conventional inner liner material brominated butyl rubber(BIIR,PN2=3.32×10^(-14)cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1)).Owing to its low cost,exceptional gas barrier properties,superior adhesion to various tire components,and co-vulcanization capabilities,the NR/BR/pVTPR composite has emerged as a promising alternative to butyl rubber in the inner liner of tires.Furthermore,by fine-tuning the cross-linking density of pVTPR,the high-gas-barrier NR/BR/pVTPR composites also demonstrated remarkable CO_(2)permselectivity,with a CO_(2)/N2 selectivity of 61.4 and a CO_(2)/O_(2)selectivity of 26.12.This innovation provides a novel strategy for CO_(2)capture and separation,with potential applications in future environmental and industrial processes.The multifunctional NR/BR/pVTPR composite,with its superior gas barrier properties and CO_(2)permselectivity,is expected to contribute to the development of safer,greener,and more cost-effective transportation solutions.
基金supported by the National Natural Science Foundation of China(21975091,22122902,and 52272208)the Fundamental Research Fund for the Central Universities of China(2662023LXPY001 and 2662021JC004).
文摘Lithium plating/stripping occurs at the a node/electrolyte interface which involves the flow of electrons from the current collector and the migration of lithium ions from the solid-electrolyte interphase(SEI).The dual continuous rapid transport of interfacial electron/ion is required for homogeneous Li deposition.Herein,we propose a strategy to improve the Li metal anode performance by rationally regulating the interfacial electron density and Li ion transport through the SEI film.This key technique involves decreasing the interfacial oxygen density of biomass-derived carbon host by regulating the arrangement of the celluloses precursor fibrils.The higher specific surface area and lower interfacial oxygen density decrease the local current density and ensure the formation of thin and even SEI film,which stabilized Li^(+)transfer through the Li/electrolyte interface.Moreover,the improved graphitization and the interconnected conducting network enhance the surface electronegativity of carbon and enable uninterruptible electron conduction.The result is continuous and rapid coupled interfacial electron/ion transport at the anode/electrolyte reaction interface,which facilitates uniform Li deposition and improves Li anode performance.The Li/C anode shows a high initial Coulombic efficiency of 98%and a long-term lifespan of over 150cycles at a practical low N/P(negative-to-positive)ratio of 1.44 in full cells.
文摘The authors regret Acknowledgements Firstly,the authors wish to acknowledge the academic support from Ruhr University Bochum during the first author's(Xiao Yan)research stay from 2018.11 to 2020.10,including the soft code implement and debug support from Vladislav Gudzulic and academic advising from Günther Meschke.
基金financial support of the National Natural Science Foundation of China(U21A20218 and 32101857)the‘Double First-Class’Key Scientific Research Project of Education Department in Gansu Province,China(GSSYLXM-02)+1 种基金the Fuxi Young Talents Fund of Gansu Agricultural University,China(Gaufx03Y10)the“Innovation Star”Program of Graduate Students in 2023 of Gansu Province,China(2023CXZX681)。
文摘The development of modern agriculture requires the reduction of water and chemical N fertilizer inputs.Increasing the planting density can maintain higher yields,but also consumes more of these restrictive resources.However,whether an increased maize density can compensate for the negative effects of reduced water and N supply on grain yield and N uptake in the arid irrigated areas remains unknown.This study is part of a long-term positioning trial that started in 2016.A split-split plot field experiment of maize was implemented in the arid irrigated area of northwestern China in 2020 to 2021.The treatments included two irrigation levels:local conventional irrigation reduced by 20%(W1,3,240 m^(3)ha^(-1))and local conventional irrigation(W2,4,050 m^(3)ha^(-1));two N application rates:local conventional N reduced by 25%(N1,270 kg ha^(-1))and local conventional N(360 kg ha^(-1));and three planting densities:local conventional density(D1,75,000 plants ha^(-1)),density increased by 30%(D2,97,500 plants ha-1),and density increased by 60%(D3,120,000 plants ha^(-1)).Our results showed that the grain yield and aboveground N accumulation of maize were lower under the reduced water and N inputs,but increasing the maize density by 30% can compensate for the reductions of grain yield and aboveground N accumulation caused by the reduced water and N supply.When water was reduced while the N application rate remained unchanged,increasing the planting density by 30% enhanced grain yield by 13.9% and aboveground N accumulation by 15.3%.Under reduced water and N inputs,increasing the maize density by 30% enhanced N uptake efficiency and N partial factor productivity,and it also compensated for the N harvest index and N metabolic related enzyme activities.Compared with W2N2D1,the N uptake efficiency and N partial factor productivity increased by 28.6 and 17.6%under W1N1D2.W1N2D2 had 8.4% higher N uptake efficiency and 13.9% higher N partial factor productivity than W2N2D1.W1N2D2 improved urease activity and nitrate reductase activity by 5.4% at the R2(blister)stage and 19.6% at the V6(6th leaf)stage,and increased net income and the benefit:cost ratio by 22.1 and 16.7%,respectively.W1N1D2 and W1N2D2 reduced the nitrate nitrogen and ammoniacal nitrogen contents at the R6 stage in the 40-100 cm soil layer,compared with W2N2D1.In summary,increasing the planting density by 30% can compensate for the loss of grain yield and aboveground N accumulation under reduced water and N inputs.Meanwhile,increasing the maize density by 30% improved grain yield and aboveground N accumulation when water was reduced by 20% while the N application rate remained constant in arid irrigation areas.
基金supported by the National Natural Science Foundation of China(52104133,52304227)the Natural Science Foundation of Hunan Province(2021JJ40465,2023JJ40548)the Opening Foundation of the State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines(SKLMRDPC20KF03).
文摘To investigate the effect of saturation on the storage-dissipation properties and failure characteristics of red sandstone,as well as the energy mechanism of rockburst prevention by water,a series of uniaxial compression and uniaxial loading–unloading tests were conducted under five saturation levels.The effect of saturation on the mechanical properties and elastic energy density was analyzed,and a method for obtaining peak energy density was proposed.The effect of saturation on the energy evolution was examined,and the energy mechanism of water in preventing rockburst was revealed.The results indicate that an increase in saturation of red sandstone decreases the input energy density,elastic energy density,dissipated energy density,peak strength and peak strain;the compaction phase of the stress–strain curve becomes shorter;the failure mode transitions from X-conjugate oblique shear to single oblique shear;the variation in the debris ejection trajectory is as follows:radiation→X-ray→oblique upward parabola→horizontal parabola→oblique downward parabola;the degree of failure intensity and fragmentation is decreased gradually.Elastic energy density is interconnected with both saturation and stress but independent of the loading path.Saturation exhibits a dual effect on the energy storage property,i.e.,increasing saturation increases the energy storage efficiency and reduces the energy storage capacity.The ratio of peak elastic energy density to peak input energy density remains constant irrespective of saturation levels.Water prevents rockburst by decreasing the energy storage capacity of surrounding rock,alleviating the stress of surrounding rock to reduce energy storage,and elevating the energy release threshold of high-energy surrounding rock.The findings of this study contribute to understanding the effect of water on rock failure from an energy perspective,as well as provide theoretical guidance for rockburst prevention by water in deep tunnels.
基金financially supported by the National Key Research and Development Program of China (2022YFA1505700,2019YFA0210403)the National Natural Science Foundation of China (52102216)+1 种基金the Natural Science Foundation of Fujian Province (2022J01625,2022-S-002)the Innovation Training Program for College Students (202310394020,cxxl-2023097,cxxl-2024131,cxxl-2024136)。
文摘Na_(3)V_(2)(PO_(4))_(3)(NVP)is gifted with fast Na^(+)conductive NASICON structure.But it still suffers from low electronic conductivity and inadequate energy density.Herein,a high-entropy modification strategy is realized by doping V^(3+)site with Ga^(3+)/Cr^(3+)/Al^(3+)/Fe^(3+)/In^(3+)simultaneously(i.e.Na_(3)V_(2-x)(GaCrAlFeIn)_x(PO_(4))_(3);x=0,0.04,0.06,and 0.08)to stimulate the V^(5+)■V^(2+)reversible multi-electron redox.Such configuration high-entropy can effectively suppress the structural collapse,enhance the redox reversibility in high working voltage(4.0 V),and optimize the electronic induced effect.The in-situ X-ray powder diffraction and in-situ electrochemical impedance spectroscopy tests efficaciously confirm the robust structu ral recovery and far lower polarization throughout an entire charge-discharge cycle during 1.6-4.3 V,respectively.Moreover,the density functional theory calculations clarify the stronger metallicity of high-entropy electrode than the bare that is derived from the more mobile free electrons surrounding the vicinity of Fermi level.By grace of high-entropy design and multi-electron transfer reactions,the optimal Na_(3)V_(1.7)(GaCrAlFeIn)_(0.06)(PO_(4))_(3)can exhibit perfect cycling/rate performances(90.97%@5000 cycles@30 C;112 mA h g^(-1)@10 C and 109 mA h g^(-1)@30 C,2.0-4.3 V).Furthermore,it can supply ultra-high185 mA h g^(-1)capacity with fa ntastic energy density(522 W h kg^(-1))in half-cells(1.4-4.3 V),and competitive capacity(121 mA h g^(-1))as well as energy density(402 W h kg^(-1))in full-cells(1.6-4.1 V),demonstrating enormous application potential for sodium-ion batteries.
基金supported by the National Natural Science Foundation of China (No.22136001)the National Key R&D Program of China (No.2022YFC3902100)+2 种基金the Key R&D Program of Hebei Province (No.21374001D)the Supercomputing Center of Dalian University of Technologythe National Supercomputer Center in Tianjin。
文摘As primary degradation products of phthalate esters,phthalate monoesters(MPEs)have been widely detected in various aquatic environments and drawn growing toxicological concerns.Hydrolysis kinetics that is of importance for assessing environmental persistence of chemicals remain elusive for MPEs.Herein,kinetics of base-catalyzed and neutral hydrolysis for 18 MPEs with different leaving groups was investigated by density functional theory calculation.Results indicate that MPEs with leaving groups having p Kaof<10 prefer dissociative transition states.MPEs are more persistent than their parents,and their hydrolysis half-lives were calculated to vary from 3.4 min to 79.2 years(p H=7–9).A quantitative structure-activity relationship model was developed for predicting the hydrolysis kinetics parameters.It was found that p Kaof the leaving groups and electronegativity of the MPEs are key factors determining the hydrolysis kinetics.This work may lay a theoretical foundation for better understanding the chemical process that governs MPE persistence in aquatic environments.
基金financially supported by the National Natural Science Foundation of China(No.51933007,No.52373047,No.52302106)the Sichuan Youth Science and Technology Innovation Research Team Project(No.2022JDTD0012)+2 种基金the Program for Featured Directions of Engineering Multidisciplines of Sichuan University(No.2020SCUNG203)the Natural Science Foundation of Sichuan Province(No.2023NSFSC0418)the Program for State Key Laboratory of Polymer Materials Engineering(No.sklpme2022-3-10)。
文摘The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors,yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability.Here,for the first time,an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate PPy-reduced graphene oxide/poly(vinylidene difluoride-cohexafluoropropylene)(PVDF-HFP)(PPy-rGO/PH)electrodes with controllable polymerization behavior and exceptional areal mass loading.The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition,achieving an impressive mass loading of 185.6 mg cm^(-2)(particularly 79.2 mg cm^(-2)for polypyrrole)and a superior areal capacitance of 25.2 F cm^(-2)at 2 mA cm^(-2)for a 12-layer electrode.In agreement with theses appealing features,an unprecedented areal energy density of 1.47 mW h cm^(-2)for a symmetrical device is registered,a rarely achieved value for other PPy/rGO-based supercapacitors.This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.
基金supported by the Beijing Natural Science Foundation(Z180013)(YC)National Natural Science Foundation of China(NSFC)under Grant No.12174358(YC)and No.11734010(YC and CW)MOST Grant No.2016YFA0301600(CW)。
文摘Density order is usually a consequence of the competition between long-range and short-range interactions.Here we report a density ordered superfluid emergent from a homogeneous Mott insulator due to the competition between frustrations and local interactions.This transition is found in a Bose–Hubbard model on a frustrated triangle lattice with an extra pairing term.Furthermore,we find a quantum phase transition between two different density ordered superfluids,which is beyond the Landau–Ginzburg(LG)paradigm.A U(1)symmetry is emergent at the critical point,while the symmetry in each density ordered superfluid is Z_(2)×Z_(3).We call the transition a‘shamrock transition’,due to its degenerate ground state in the parameter space being a shamrock-like curve rather than a circle in an LG-type transition.Effective low energy theories are established for the two transitions mentioned above and we find their resemblance and differences with clock models.
基金National Natural Science Foundation of China (Nos. 22078242 and U20A20153)Applied Basic Research Program of Yunnan Province (Nos. 202101BE070001-032 and 202101BH070002)。
文摘Fe-N-C catalysts are widely considered as promising non-precious-metal candidates for electrocatalytic oxygen reduction reaction(ORR),Yet despite their high catalytic activity through rational modulation,challenges remain in their low site density and unsatisfactory mass transfer structure.Herein,we present a structural engineering approach employing a soft-template coating strategy to fabricate a hollow and hierarchically porous N-doped carbon framework anchored with atomically dispersed Fe sites(FeNCh) as an efficient ORR catalyst.The combination of hierarchical porosity and high exterior surface area is proven crucial for exposing more active sites,which gives rise to a remarkable ORR performance with a half-wave potential of 0.902 V in 0.1 m KOH and 0.814 V in 0.1 m HClO_(4),significantly outperforming its counterpart with solid structure and dominance of micropores(FeNC-s).The mass transfer property is revealed by in-situ electrochemical impedance spectroscopy(EIS) measurement.The distribution of relaxation time(DRT) analysis is further introduced to deconvolve the kinetic and mass transport processes,which demonstrates an alleviated mass transport resistance for FeNC-h,validating the effectiveness of structural engineering.This work not only provides an effective structural engineering approach but also contributes to the comprehensive mass transfer evaluation on advanced electrocatalyst for energy conversion applications.
文摘A prediction framework based on the evolution of pattern motion probability density is proposed for the output prediction and estimation problem of non-Newtonian mechanical systems,assuming that the system satisfies the generalized Lipschitz condition.As a complex nonlinear system primarily governed by statistical laws rather than Newtonian mechanics,the output of non-Newtonian mechanics systems is difficult to describe through deterministic variables such as state variables,which poses difficulties in predicting and estimating the system’s output.In this article,the temporal variation of the system is described by constructing pattern category variables,which are non-deterministic variables.Since pattern category variables have statistical attributes but not operational attributes,operational attributes are assigned to them by posterior probability density,and a method for analyzing their motion laws using probability density evolution is proposed.Furthermore,a data-driven form of pattern motion probabilistic density evolution prediction method is designed by combining pseudo partial derivative(PPD),achieving prediction of the probability density satisfying the system’s output uncertainty.Based on this,the final prediction estimation of the system’s output value is realized by minimum variance unbiased estimation.Finally,a corresponding PPD estimation algorithm is designed using an extended state observer(ESO)to estimate the parameters to be estimated in the proposed prediction method.The effectiveness of the parameter estimation algorithm and prediction method is demonstrated through theoretical analysis,and the accuracy of the algorithm is verified by two numerical simulation examples.
基金supported by the Biological Breeding-National Science and Technology Major Project(2023ZD0403305)National Natural Science Foundation of China(32101845)+1 种基金the National Key Research and Development Program of China(2023YFE0105000)the China Agriculture Research System(CARS-04).
文摘Dense cropping increases crop yield but intensifies resource competition,which reduces single plant yield and limits potential yield growth.Optimizing canopy spacing could enhance resource utilization,support crop morphological development and increase yield.Here,a three-year study was performed to verify the feasibility of adjusting row spacing to further enhance yield in densely planted soybeans.Of three row-spacing configurations(40-40,20-40,and 20-60 cm)and two planting densities(normal 180,000 plants ha 1 and high 270,000 plants ha 1).The differences in canopy structure,plant morphological development,photosynthetic capacity and their impact on yield were analyzed.Row spacing configurations have a significant effect on canopy transmittance(CT).The 20-60 cm row spacing configuration increased CT and creates a favorable canopy light environment,in which plant height is reduced,while branching is promoted.This approach reduces plant competition,optimizes the developments of leaf area per plant,specific leaf area,leaf area development rate,leaf area duration and photosynthetic physiological indices(F_(v)/F_(m),ETR,P_(n)).The significant increase of 11.9%-34.2%in canopy apparent photosynthesis(CAP)is attributed to the significant optimization of plant growth and photosynthetic physiology through CT,an important contributing factor to yield increases.The yield in the 20-60 cm treatment is 4.0%higher than in equidistant planting under normal planting density,but 5.9%under high density,primarily driven by CAP and pod number.These findings suggest that suitable row spacing configurations optimize the light environment for plants,promote source-sink transformation in soybeans,and further improve yield.In practice,a 20-60 cm row spacing configuration could be employed for high-density soybean planting to achieve a more substantial yield gain.
