Lithium-sulfur(Li-S)chemistry reaction opens a new battery era with high energy density;meanwhile,multiple electrons migration leads to the complex phase transition of sulfur species.To manipulate the binding strength...Lithium-sulfur(Li-S)chemistry reaction opens a new battery era with high energy density;meanwhile,multiple electrons migration leads to the complex phase transition of sulfur species.To manipulate the binding strength of multiple key intermediates more efficiently,the bimetallic TiVC MXene is utilized to realize multi-dimensional catalysis.Based on the macroscopic three-dimensional(3D)structure using two-dimensional(2D)MXene architecture,electron conductivity and sulfur utilization are improved.Microscopically,Ti-V catalytic systems regulate multiple reaction intermediates through intermetallic synergies customized surface properties and atomic scale coordination,thereby improving electronic and ionic conductivity.In-situ Raman spectroscopy and electrochemical analysis show that the conversion rate of polysulfides was accelerated during the charge-discharge process.The Ti-V interaction exhibits unique catalytic activity and regulates multiple continuous processes of sulfur species phase transformation,which are essential for the excellent energy performance of Li-S batteries.This study not only clarifies the catalytic mechanism of Ti-V at different dimensions but also proposes a promising strategy for the design of advanced catalytic systems in energy storage technology.展开更多
Green and environmentally friendly electrocatalytic nitrogen(N_(2))fixation to synthesize ammonia(NH3)is recognized as an effective method to replace the traditional Haber-Bosch process.However,the difficulties in N_(...Green and environmentally friendly electrocatalytic nitrogen(N_(2))fixation to synthesize ammonia(NH3)is recognized as an effective method to replace the traditional Haber-Bosch process.However,the difficulties in N_(2) adsorption and fracture of hard N≡N bond still remain major challenges in electrocatalytic N_(2) reduction reactions(NRR).From the perspectives of enhancing N_(2) adsorption and providing more catalytic sites,two-dimensional(2D)FeS_(2) nanosheets and three-dimensional(3D)metal organic framework-derived ZnS embedded within N-doped carbon polyhedras are grown on the carbon cloth(CC)template in this work.Thus,a composite NRR catalyst with multi-dimensional structures,which is signed as FeS_(2)/ZnS-NC@CC,is obtained for using over a wide pH range.The uniform distribution of hollow ZnS-NC frameworks and FeS_(2) nanosheets on the surface of CC largely increase the N_(2) enrichment efficiency and offer more active sites,while the CC skeleton acts as an independent conductive substrate and S-doping helps promote the fracture of N≡N bond during the NRR reaction.As a result,the FeS_(2)/ZnS-NC@CC electrode achieves a high Faraday efficiency of 46.84%and NH3 yield of 58.52μg h^(−1) mg^(−1) at-0.5 V vs.Ag/AgCl in 0.1 M KOH.Furthermore,the FeS_(2)/ZnS-NC@CC electrode displays excellent NRR catalytic activity in acidic and neutral electrolytes as well,which outperforms most previously reported electrocatalysts including noble metals.Therefore,this work provides a new way for the design of multi-dimensional electrocatalysts with excellent electrocatalytic efficiency and stability for NRR applications.展开更多
Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'...Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.展开更多
In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented...In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented product FGPA-G 2-H on Aβ25-35-induced PC 12 cells were explored.The structure of GPA-G 2-H was determined by means of zeta potential analysis,FTIR,HPLC,XRD,GC-MS and NMR.The backbone of GPA-G 2-H was mainly composed of→4)-α-D-Glcp-(1→with branches substituted at O-3.Notably,GPA-G 2-H was degraded by intestinal microbiota in vitro with total sugar content and pH value decreasing,and short-chain fatty acids(SCFAs)increasing.Moreover,GPA-G 2-H significantly promoted the proliferation of Lactobacillus,Muribaculaceae and Weissella,thereby making positive alterations in intestinal microbiota composition.Additionally,FGPA-G 2-H activated the Nrf 2/HO-1 signaling pathway,enhanced HO-1,NQO 1,SOD and GSH-Px,while inhabited Keap 1,MDA and LDH,which alleviated Aβ-induced oxidative stress in PC 12 cells.These provide a solid theoretical basis for the further development of ginseng polysaccharides as functional food and antioxidant drugs.展开更多
To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content ...To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.展开更多
Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,...Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.展开更多
Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is p...Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.展开更多
Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled t...Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.展开更多
Aqueous zinc-ion batteries(AZIBs)have garnered considerable attention as promising post-lithium energy storage technologies owing to their intrinsic safety,cost-effectiveness,and competitive gravimetric energy density...Aqueous zinc-ion batteries(AZIBs)have garnered considerable attention as promising post-lithium energy storage technologies owing to their intrinsic safety,cost-effectiveness,and competitive gravimetric energy density.However,their practical commercialization is hindered by critical challenges on the anode side,including dendrite growth and parasitic reactions at the anode/electrolyte interface.Recent studies highlight that rational electrolyte structure engineering offers an effective route to mitigate these issues and strengthen the electrochemical performance of the zinc metal anode.In this review,we systematically summarize state-of-the-art strategies for electrolyte optimization,with a particular focus on the zinc salts regulation,electrolyte additives,and the construction of novel electrolytes,while elucidating the underlying design principles.We further discuss the key structure–property relationships governing electrolyte behavior to provide guidance for the development of next-generation electrolytes.Finally,future perspectives on advanced electrolyte design are proposed.This review aims to serve as a comprehensive reference for researchers exploring high-performance electrolyte engineering in AZIBs.展开更多
Porous carbon microspheres are widely regarded as a superior CO_(2) adsorbent due to their exceptional efficiency and affordability.However,better adsorption performance is very attractive for porous carbon microspher...Porous carbon microspheres are widely regarded as a superior CO_(2) adsorbent due to their exceptional efficiency and affordability.However,better adsorption performance is very attractive for porous carbon microspheres.And modification of the pore structure is one of the effective strategies.In this study,multi-cavity mesoporous carbon microspheres were successfully synthesized by the synergistic method of soft and hard templates,during which a phenolic resin with superior thermal stability was employed as the carbon precursor and a mixture of silica sol and F108 as the mesoporous template.Carbon microspheres with multi-cavity mesoporous structures were prepared,and all the samples showed highly even mesopores,with diameters around 12 nm.The diameter of these microspheres decreased from 396.8 nm to about 182.5 nm with the increase of silica sol.After CO_(2) activation,these novel carbon microspheres(APCF0.5-S1.75)demonstrated high specific surface area(983.3 m^(2)/g)and remarkable CO_(2) uptake of 4.93 mmol/g at 0℃ and1 bar.This could be attributed to the unique multi-cavity structure,which offers uniform mesoporous pore channels,minimal CO_(2) transport of and a greater number of active sites for CO_(2) adsorption.展开更多
Two CoⅡ-based complexes,{[Co(dps)_(2)(N_(3))_(2)]·H_(2)O}_n(1)and[Co(dps)_(2)(N_(3))_(2)]_n(2),show a 1D chain and a 3D network,respectively.The central CoⅡions in the complexes have the same coordination envir...Two CoⅡ-based complexes,{[Co(dps)_(2)(N_(3))_(2)]·H_(2)O}_n(1)and[Co(dps)_(2)(N_(3))_(2)]_n(2),show a 1D chain and a 3D network,respectively.The central CoⅡions in the complexes have the same coordination environment with the[Co(dps)_(4)(N_(3))_(2)]unit.Although the differences in crystal parameters are nearly negligible,their magnetic properties are very different.AC susceptibility data show that 1 behaves as a typical field-induced single-ion magnet(SIM)with the out-of-phase(χ_(M)”)signals,while 2 shows ac signals ofχ_(M)”without peaks even under applied dc filed within our measurement window.Far-IR magneto-spectra(FIRMS)show strong spin-phonon couplings at 0 T in 2,likely making the magnetic relaxation in 2 fast,while the couplings are negligible in 1.Small spin-phonon coupling in 1 likely leads to slower magnetic relaxation,making 1 a SIM.The difference in the properties is due to the structural rigidity of 2 in its 3D network,leading to stronger spin-phonon coupling.Combined high-field EPR(HF-EPR)and FIRMS studies give spin-Hamiltonian parameters,including D=64.0(9)cm^(-1),|E|=15.7(2)cm^(-1)for 1 and D=80.0(2)cm^(-1),|E|=19.0(1)cm^(-1)for 2.展开更多
Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and v...Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and viable quantum algorithms for simulating large-scale materials are still limited.We propose and implement random-state quantum algorithms to calculate electronic-structure properties of real materials.Using a random state circuit on a small number of qubits,we employ real-time evolution with first-order Trotter decomposition and Hadamard test to obtain electronic density of states,and we develop a modified quantum phase estimation algorithm to calculate real-space local density of states via direct quantum measurements.Furthermore,we validate these algorithms by numerically computing the density of states and spatial distributions of electronic states in graphene,twisted bilayer graphene quasicrystals,and fractal lattices,covering system sizes from hundreds to thousands of atoms.Our results manifest that the random-state quantum algorithms provide a general and qubit-efficient route to scalable simulations of electronic properties in large-scale periodic and aperiodic materials.展开更多
When evaluating the seismic safety and reliability of complex engineering structures,it is a critical problem to reasonably consider the randomness and multi-dimensional nature of ground motions.To this end,a proposed...When evaluating the seismic safety and reliability of complex engineering structures,it is a critical problem to reasonably consider the randomness and multi-dimensional nature of ground motions.To this end,a proposed modeling strategy of multi-dimensional stochastic earthquakes is addressed in this study.This improved seismic model has several merits that enable it to better provide seismic analyses of structures.Specifically,at first,the ground motion model is compatible with the design response spectrum.Secondly,the evolutionary power spectrum involved in the model and the design response spectrum are constructed accordingly with sufficient consideration of the correlation between different seismic components.Thirdly,the random function-based dimension-reduction representation is applied,by which seismic modeling is established,with three elementary random variables.Numerical simulations of multi-dimensional stochastic ground motions in a specific design scenario indicate the effectiveness of the proposed modeling strategy.Moreover,the multi-dimensional seismic response and the global reliability of a high-rise frame-core tube structure is discussed in detail to further illustrate the engineering applicability of the proposed method.The analytical investigations demonstrate that the suggested stochastic model of multi-dimensional ground motion is available for accurate seismic response analysis and dynamic reliability assessment of complex engineering structures for performance-based seismic resistance design.展开更多
The simulation of hypersonic flows with fully unstructured(tetrahedral)grids has severe problems with respect to the prediction of stagnation region heating,due to the random face orientation without alignment to the ...The simulation of hypersonic flows with fully unstructured(tetrahedral)grids has severe problems with respect to the prediction of stagnation region heating,due to the random face orientation without alignment to the bow shock.To improve the accuracy of aero-heating predictions,three multi-dimensional approaches on unstructured grids are coupled in our Reynolds-averaged Navier-Stokes(RANS)solver,including multi-dimensional upwind flux reconstruction(MUP),multi-dimensional limiter(MLP-u2)and multi-dimensional gradient reconstruction(MLR).The coupled multi-dimensional RANS solver is validated by several typical verification and validation(V&V)cases,including hypersonic flows over a cylinder,a blunt biconic,and a double-ellipsoid,with commonly used prism/tetrahedral hybrid grids.Finally,the coupled multi-dimensional solver is applied to simulating the heat flux distribution over a 3D engineering configuration,i.e.a Hermes-like space shuttle model.The obtained numerical results are compared with experimental data.The predicted results demonstrate that the coupled multi-dimensional approach has a good prediction capability on aerodynamic heating over a wide range of complex engineering configurations.展开更多
In this article, we get non-selfsimilar elementary waves of the conservation laws in another kind of view, which is different from the usual self-similar transformation. The solution has different global structure. Th...In this article, we get non-selfsimilar elementary waves of the conservation laws in another kind of view, which is different from the usual self-similar transformation. The solution has different global structure. This article is divided into three parts. The first part is introduction. In the second part, we discuss non-selfsimilar elementary waves and their interactions of a class of twodimensional conservation laws. In this case, we consider the case that the initial discontinuity is parabola with u＋ 〉 0, while explicit non-selfsirnilar rarefaction wave can be obtained. In the second part, we consider the solution structure of case u＋ 〈 0. The new solution structures are obtained by the interactions between different elementary waves, and will continue to interact with other states. Global solutions would be very different from the situation of one dimension.展开更多
Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers fro...Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers from dendrite problems.Functional carbon materials(FCMs)have demonstrated their great potential in suppressing metal dendrites benefitting from the multiple merits such as chemical tunability and capability of multi-dimensional structure assembly.Here,we initiate a review to present the recent progress in employing FCMs to deal with dendrite problems.It focuses on the surface chemistry and multi-dimensional carbon material engineering,which systematically overcomes the problems through diverse methods,such as reinforcing desolvation,improving interface compatibility,homogenizing electric field,buffering volume expansion and lattice mismatch.In addition,we also refine the long-standing debate about whether surface defects in FCMs are beneficial to suppress the metal dendrites or not,especially in the non-aqueous electrolyte regime.Finally,the remaining challenges for utilizing FCMs to suppress metal dendrites and the possible solutions are proposed to guide the future development.展开更多
A new kind of multi-dimensional WC-10Co4Cr coating which is composed of nano,submicron,micron WC grains and CoCr alloy,was developed by high velocity oxy-fuel(HVOF)spraying.Porosity,microhardness,fracture toughness an...A new kind of multi-dimensional WC-10Co4Cr coating which is composed of nano,submicron,micron WC grains and CoCr alloy,was developed by high velocity oxy-fuel(HVOF)spraying.Porosity,microhardness,fracture toughness and cavitation erosion resistance of the multi-dimensional coating were investigated in comparison with the bimodal and nanostructured WC?10Co4Cr coatings.Moreover,the cavitation erosion behavior and mechanism of the multi-dimensional coating were explored.Results show that HVOF sprayed multi-dimensional WC-10Co4Cr coating possesses low porosity(≤0.32%)and high fracture toughness without obvious nano WC decarburization during spraying.Furthermore,it is discovered that the multi-dimensional WC-10Co4Cr coating exhibits the best cavitation erosion resistance which is enhanced by approximately 28%and 34%,respectively,compared with the nanostructured and bimodal coatings in fresh water.The superior cavitation resistance of multi-dimensional WC-10Co4Cr coating may originate from the unique micro?nano structure and excellent properties,which can effectively obstruct the formation and propagation of cavitation erosion cracks.展开更多
For the two-dimensional(2D)scalar conservation law,when the initial data contain two different constant states and the initial discontinuous curve is a general curve,then complex structures of wave interactions will b...For the two-dimensional(2D)scalar conservation law,when the initial data contain two different constant states and the initial discontinuous curve is a general curve,then complex structures of wave interactions will be generated.In this paper,by proposing and investigating the plus envelope,the minus envelope,and the mixed envelope of 2D non-selfsimilar rarefaction wave surfaces,we obtain and the prove the new structures and classifications of interactions between the 2D non-selfsimilar shock wave and the rarefaction wave.For the cases of the plus envelope and the minus envelope,we get and prove the necessary and sufficient criterion to judge these two envelopes and correspondingly get more general new structures of 2D solutions.展开更多
Currently,the Al_(2)O_(3)content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%,making it challenging to overcome this limitation.Unlike most studies that concentrated on...Currently,the Al_(2)O_(3)content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%,making it challenging to overcome this limitation.Unlike most studies that concentrated on managing the MgO/Al_(2)O_(3)ratio or basicity,this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO-MgO-Al_(2)O_(3)-SiO_(2)slag system,providing theoretical guidance and data to facilitate the application of high-alumina ores.The results revealed that the viscosity first decreased and then increased with higher MgO substitution,reaching a minimum at 15mol%MgO concentration.Fourier transform infrared spectroscopy(FTIR)results found that the depths of the troughs representing[SiO_(4)]tetrahedra,[AlO_(4)]tetrahedra,and Si-O-Al bending became progressively deeper with increased MgO substitution.Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the X_(Q^(3))/X_(Q^(2))(X_(Q^(i))is the molar fraction of Q^(i) unit,and i is the number of bridging oxygens in a[SiO_(4)]tetrahedral unit)ratio increased from 2.30 and 1.02 to 2.52 and 2.14,respectively,indicating a progressive polymerization of the silicate structure.X-ray photoelectron spectroscopy(XPS)results highlighted that non-bridging oxygen content decreased from 77.97mol% to 63.41mol% with increasing MgO concentration,whereas bridging oxygen and free oxygen contents increased.Structural analysis demonstrated a gradual increase in the polymerization degree of the tetrahedral structure with the increase in MgO substitution.However,bond strength is another important factor affecting the slag viscosity.The occurrence of a viscosity minimum can be attributed to the complex evolution of bond strengths of non-bridging oxygens generated during depolymerization of the[SiO_(4)]and[AlO_(4)]tetrahedral structures by CaO and MgO.展开更多
Recently,multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials.Nevertheless,excessive stack and agglomeration for low-dimension carbon nanomaterials inducing imped...Recently,multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials.Nevertheless,excessive stack and agglomeration for low-dimension carbon nanomaterials inducing impedance mismatch are significant challenges.Herein,the delicate“3D helix-2D sheet-1D fiber-0D dot”hierarchical aerogels have been successfully synthesized,for the first time,by sequential processes of hydrothermal self-assembly and in-situ chemical vapor deposition method.Particularly,the graphene sheets are uniformly intercalated by 3D helical carbon nanocoils,which give a feasible solution to the mentioned problem and endows the as-obtained aerogel with abundant porous structures and better dielectric properties.Moreover,by adjusting the content of 0D core-shell structured particles and the parameters for growth of the 1D carbon nanofibers,tunable electromagnetic properties and excellent impedance matching are achieved,which plays a vital role in the microwave absorption performance.As expected,the optimized aerogels harvest excellent performance,including broad effective bandwidth and strong reflection loss at low filling ratio and thin thickness.This work gives valuable guidance and inspiration for the design of hierarchical materials comprised of dimensional gradient structures,which holds great application potential for electromagnetic wave attenuation.展开更多
基金the financial support provided by the National Natural Science Foundation of China(No.51932005)the Liaoning Revitalization Talents Program(No.XLYC1807175)+1 种基金the Development Plan of Science and Technology of Jilin Province,China(YDZJ202301ZYTS280)the Natural Science Foundation of Jilin Province(YDZJ202401316ZYTS)。
文摘Lithium-sulfur(Li-S)chemistry reaction opens a new battery era with high energy density;meanwhile,multiple electrons migration leads to the complex phase transition of sulfur species.To manipulate the binding strength of multiple key intermediates more efficiently,the bimetallic TiVC MXene is utilized to realize multi-dimensional catalysis.Based on the macroscopic three-dimensional(3D)structure using two-dimensional(2D)MXene architecture,electron conductivity and sulfur utilization are improved.Microscopically,Ti-V catalytic systems regulate multiple reaction intermediates through intermetallic synergies customized surface properties and atomic scale coordination,thereby improving electronic and ionic conductivity.In-situ Raman spectroscopy and electrochemical analysis show that the conversion rate of polysulfides was accelerated during the charge-discharge process.The Ti-V interaction exhibits unique catalytic activity and regulates multiple continuous processes of sulfur species phase transformation,which are essential for the excellent energy performance of Li-S batteries.This study not only clarifies the catalytic mechanism of Ti-V at different dimensions but also proposes a promising strategy for the design of advanced catalytic systems in energy storage technology.
基金support from the Natural Science Foundation of Shanghai(20ZR1401400,18ZR1401600)Shanghai Scientific and Technological Innovation Project(18JC1410600).
文摘Green and environmentally friendly electrocatalytic nitrogen(N_(2))fixation to synthesize ammonia(NH3)is recognized as an effective method to replace the traditional Haber-Bosch process.However,the difficulties in N_(2) adsorption and fracture of hard N≡N bond still remain major challenges in electrocatalytic N_(2) reduction reactions(NRR).From the perspectives of enhancing N_(2) adsorption and providing more catalytic sites,two-dimensional(2D)FeS_(2) nanosheets and three-dimensional(3D)metal organic framework-derived ZnS embedded within N-doped carbon polyhedras are grown on the carbon cloth(CC)template in this work.Thus,a composite NRR catalyst with multi-dimensional structures,which is signed as FeS_(2)/ZnS-NC@CC,is obtained for using over a wide pH range.The uniform distribution of hollow ZnS-NC frameworks and FeS_(2) nanosheets on the surface of CC largely increase the N_(2) enrichment efficiency and offer more active sites,while the CC skeleton acts as an independent conductive substrate and S-doping helps promote the fracture of N≡N bond during the NRR reaction.As a result,the FeS_(2)/ZnS-NC@CC electrode achieves a high Faraday efficiency of 46.84%and NH3 yield of 58.52μg h^(−1) mg^(−1) at-0.5 V vs.Ag/AgCl in 0.1 M KOH.Furthermore,the FeS_(2)/ZnS-NC@CC electrode displays excellent NRR catalytic activity in acidic and neutral electrolytes as well,which outperforms most previously reported electrocatalysts including noble metals.Therefore,this work provides a new way for the design of multi-dimensional electrocatalysts with excellent electrocatalytic efficiency and stability for NRR applications.
文摘Six new lanthanide complexes:[Ln(3,4-DEOBA)3(4,4'-DM-2,2'-bipy)]2·2C_(2)H_(5)OH,[Ln=Dy(1),Eu(2),Tb(3),Sm(4),Ho(5),Gd(6);3,4-DEOBA-=3,4-diethoxybenzoate,4,4'-DM-2,2'-bipy=4,4'-dimethyl-2,2'-bipyridine]were successfully synthesized by the volatilization of the solution at room temperature.The crystal structures of six complexes were determined by single-crystal X-ray diffraction technology.The results showed that the complexes all have a binuclear structure,and the structures contain free ethanol molecules.Moreover,the coordination number of the central metal of each structural unit is eight.Adjacent structural units interact with each other through hydrogen bonds and further expand to form 1D chain-like and 2D planar structures.After conducting a systematic study on the luminescence properties of complexes 1-4,their emission and excitation spectra were obtained.Experimental results indicated that the fluorescence lifetimes of complexes 2 and 3 were 0.807 and 0.845 ms,respectively.The emission spectral data of complexes 1-4 were imported into the CIE chromaticity coordinate system,and their corre sponding luminescent regions cover the yellow light,red light,green light,and orange-red light bands,respectively.Within the temperature range of 299.15-1300 K,the thermal decomposition processes of the six complexes were comprehensively analyzed by using TG-DSC/FTIR/MS technology.The hypothesis of the gradual loss of ligand groups during the decomposition process was verified by detecting the escaped gas,3D infrared spectroscopy,and ion fragment information detected by mass spectrometry.The specific decomposition path is as follows:firstly,free ethanol molecules and neutral ligands are removed,and finally,acidic ligands are released;the final product is the corresponding metal oxide.CCDC:2430420,1;2430422,2;2430419,3;2430424,4;2430421,5;2430423,6.
基金Supported by the National Key Research and Development Program of Traditional Chinese Medicine Modernization Project,China(No.2023YFC3504000)the Science and Technology Development Project of Jilin Province,China(No.20240404043ZP)the Science and Technology Innovation Cooperation Project of Changchun Science and Technology Bureau and Chinese Academy of Sciences,China(No.23SH14)。
文摘In this study,a novel polysaccharide GPA-G 2-H was derived from ginseng.Furthermore,the coherent study of its structural characteristics,fermented characteristics in vitro,as well as antioxidant mechanism of fermented product FGPA-G 2-H on Aβ25-35-induced PC 12 cells were explored.The structure of GPA-G 2-H was determined by means of zeta potential analysis,FTIR,HPLC,XRD,GC-MS and NMR.The backbone of GPA-G 2-H was mainly composed of→4)-α-D-Glcp-(1→with branches substituted at O-3.Notably,GPA-G 2-H was degraded by intestinal microbiota in vitro with total sugar content and pH value decreasing,and short-chain fatty acids(SCFAs)increasing.Moreover,GPA-G 2-H significantly promoted the proliferation of Lactobacillus,Muribaculaceae and Weissella,thereby making positive alterations in intestinal microbiota composition.Additionally,FGPA-G 2-H activated the Nrf 2/HO-1 signaling pathway,enhanced HO-1,NQO 1,SOD and GSH-Px,while inhabited Keap 1,MDA and LDH,which alleviated Aβ-induced oxidative stress in PC 12 cells.These provide a solid theoretical basis for the further development of ginseng polysaccharides as functional food and antioxidant drugs.
基金Supported by the Science and Technology Cooperation and Exchange special project of Cooperation of Shanxi Province(202404041101014)the Fundamental Research Program of Shanxi Province(202403021212333)+3 种基金the Joint Funds of the National Natural Science Foundation of China(U24A20555)the Lvliang Key R&D of University-Local Cooperation(2023XDHZ10)the Initiation Fund for Doctoral Research of Taiyuan University of Science and Technology(20242026)the Outstanding Doctor Funding Award of Shanxi Province(20242080).
文摘To elucidate the effect of calcite-regulated activated carbon(AC)structure on low-temperature denitrification performance of SCR catalysts,this work prepared a series of Mn-Ce/De-AC-xCaCO_(3)(x is the calcite content in coal)catalysts were prepared by the incipient wetness impregnation method,followed by acid washing to remove calcium-containing minerals.Comprehensive characterization and low-temperature denitrification tests revealed that calcite-induced structural modulation of coal-derived AC significantly enhances catalytic activity.Specifically,NO conversion increased from 88.3%of Mn-Ce/De-AC to 91.7%of Mn-Ce/De-AC-1CaCO_(3)(210℃).The improved SCR denitrification activity results from the enhancement of physicochemical properties including higher Mn^(4+)content and Ce^(4+)/Ce^(3+)ratio,an abundance of chemisorbed oxygen and acidic sites,which could strengthen the SCR reaction pathways(richer NH_(3)activated species and bidentate nitrate active species).Therefore,NO removal is enhanced.
基金supported by the National Key Research and Development Program of China(2024YFA1612900)the National Natural Science Foundation of China(Grant No.52103365 and No.12375270)the Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2021ZT09L227).
文摘Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.
基金supported by National Natural Science Foundation of China(No.52025055 and 52275571)Basic Research Operation Fund of China(No.xzy012024024).
文摘Tilted metasurface nanostructures,with excellent physical properties and enormous application potential,pose an urgent need for manufacturing methods.Here,electric-field-driven generative-nanoimprinting technique is proposed.The electric field applied between the template and the substrate drives the contact,tilting,filling,and holding processes.By accurately controlling the introduced included angle between the flexible template and the substrate,tilted nanostructures with a controllable angle are imprinted onto the substrate,although they are vertical on the template.By flexibly adjusting the electric field intensity and the included angle,large-area uniform-tilted,gradient-tilted,and high-angle-tilted nanostructures are fabricated.In contrast to traditional replication,the morphology of the nanoimprinting structure is extended to customized control.This work provides a cost-effective,efficient,and versatile technology for the fabrication of various large-area tilted metasurface structures.As an illustration,a tilted nanograting with a high coupling efficiency is fabricated and integrated into augmented reality displays,demonstrating superior imaging quality.
基金supported by the Research Project on Strengthening the Construction of an Important Ecological Security Barrier in Northern China by Higher Education Institutions in the Inner Mongolia Autonomous Region(STAQZX202313)the Inner Mongolia Autonomous Region Education Science‘14th Five-Year Plan’2024 Annual Research Project(NGJGH2024635).
文摘Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.
基金supported by the Natural Science Foundation of China(Nos.52125202,52202100,and U24A2065)the Natural Science Foundation of Jiangsu Province(BK20243016)Fundamental Research Funds for the Central Universities,China Postdoctoral Science Foundation(No.2024T171166).
文摘Aqueous zinc-ion batteries(AZIBs)have garnered considerable attention as promising post-lithium energy storage technologies owing to their intrinsic safety,cost-effectiveness,and competitive gravimetric energy density.However,their practical commercialization is hindered by critical challenges on the anode side,including dendrite growth and parasitic reactions at the anode/electrolyte interface.Recent studies highlight that rational electrolyte structure engineering offers an effective route to mitigate these issues and strengthen the electrochemical performance of the zinc metal anode.In this review,we systematically summarize state-of-the-art strategies for electrolyte optimization,with a particular focus on the zinc salts regulation,electrolyte additives,and the construction of novel electrolytes,while elucidating the underlying design principles.We further discuss the key structure–property relationships governing electrolyte behavior to provide guidance for the development of next-generation electrolytes.Finally,future perspectives on advanced electrolyte design are proposed.This review aims to serve as a comprehensive reference for researchers exploring high-performance electrolyte engineering in AZIBs.
基金supported by the National Key R&D Program of China(No.2021YFB3501102).
文摘Porous carbon microspheres are widely regarded as a superior CO_(2) adsorbent due to their exceptional efficiency and affordability.However,better adsorption performance is very attractive for porous carbon microspheres.And modification of the pore structure is one of the effective strategies.In this study,multi-cavity mesoporous carbon microspheres were successfully synthesized by the synergistic method of soft and hard templates,during which a phenolic resin with superior thermal stability was employed as the carbon precursor and a mixture of silica sol and F108 as the mesoporous template.Carbon microspheres with multi-cavity mesoporous structures were prepared,and all the samples showed highly even mesopores,with diameters around 12 nm.The diameter of these microspheres decreased from 396.8 nm to about 182.5 nm with the increase of silica sol.After CO_(2) activation,these novel carbon microspheres(APCF0.5-S1.75)demonstrated high specific surface area(983.3 m^(2)/g)and remarkable CO_(2) uptake of 4.93 mmol/g at 0℃ and1 bar.This could be attributed to the unique multi-cavity structure,which offers uniform mesoporous pore channels,minimal CO_(2) transport of and a greater number of active sites for CO_(2) adsorption.
基金supported by the National Key Research and Development Program of China(No.2021YFA1600304)Joint Fund for Regional Innovation and Development(No.U20A2073)+4 种基金National Natural Science Foundation of China(Nos.22373048,21973038,61904119 and 22105089)Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(No.20212BCD42018)US National Science Foundation(NSF,No.CHE-2055499)the Interdisciplinary program of Wuhan National High Magnetic Field Center(No.WHMFC202133)the support of the NSF Research Traineeship Program(No.DGE-2152168)。
文摘Two CoⅡ-based complexes,{[Co(dps)_(2)(N_(3))_(2)]·H_(2)O}_n(1)and[Co(dps)_(2)(N_(3))_(2)]_n(2),show a 1D chain and a 3D network,respectively.The central CoⅡions in the complexes have the same coordination environment with the[Co(dps)_(4)(N_(3))_(2)]unit.Although the differences in crystal parameters are nearly negligible,their magnetic properties are very different.AC susceptibility data show that 1 behaves as a typical field-induced single-ion magnet(SIM)with the out-of-phase(χ_(M)”)signals,while 2 shows ac signals ofχ_(M)”without peaks even under applied dc filed within our measurement window.Far-IR magneto-spectra(FIRMS)show strong spin-phonon couplings at 0 T in 2,likely making the magnetic relaxation in 2 fast,while the couplings are negligible in 1.Small spin-phonon coupling in 1 likely leads to slower magnetic relaxation,making 1 a SIM.The difference in the properties is due to the structural rigidity of 2 in its 3D network,leading to stronger spin-phonon coupling.Combined high-field EPR(HF-EPR)and FIRMS studies give spin-Hamiltonian parameters,including D=64.0(9)cm^(-1),|E|=15.7(2)cm^(-1)for 1 and D=80.0(2)cm^(-1),|E|=19.0(1)cm^(-1)for 2.
基金supported by the Major Project for the Integration of ScienceEducation and Industry (Grant No.2025ZDZX02)。
文摘Classical computation of electronic properties in large-scale materials remains challenging.Quantum computation has the potential to offer advantages in memory footprint and computational scaling.However,general and viable quantum algorithms for simulating large-scale materials are still limited.We propose and implement random-state quantum algorithms to calculate electronic-structure properties of real materials.Using a random state circuit on a small number of qubits,we employ real-time evolution with first-order Trotter decomposition and Hadamard test to obtain electronic density of states,and we develop a modified quantum phase estimation algorithm to calculate real-space local density of states via direct quantum measurements.Furthermore,we validate these algorithms by numerically computing the density of states and spatial distributions of electronic states in graphene,twisted bilayer graphene quasicrystals,and fractal lattices,covering system sizes from hundreds to thousands of atoms.Our results manifest that the random-state quantum algorithms provide a general and qubit-efficient route to scalable simulations of electronic properties in large-scale periodic and aperiodic materials.
基金National Natural Science Foundation of China under Grant Nos.51978543,52108444,and 51778343Plan of Outstanding Young and Middle-aged Scientific and Technological Innovation Team in the Universities of Hubei Province with Project No.T2020010Natural Science Foundation of Hebei Province under Grant No.E2021512001。
文摘When evaluating the seismic safety and reliability of complex engineering structures,it is a critical problem to reasonably consider the randomness and multi-dimensional nature of ground motions.To this end,a proposed modeling strategy of multi-dimensional stochastic earthquakes is addressed in this study.This improved seismic model has several merits that enable it to better provide seismic analyses of structures.Specifically,at first,the ground motion model is compatible with the design response spectrum.Secondly,the evolutionary power spectrum involved in the model and the design response spectrum are constructed accordingly with sufficient consideration of the correlation between different seismic components.Thirdly,the random function-based dimension-reduction representation is applied,by which seismic modeling is established,with three elementary random variables.Numerical simulations of multi-dimensional stochastic ground motions in a specific design scenario indicate the effectiveness of the proposed modeling strategy.Moreover,the multi-dimensional seismic response and the global reliability of a high-rise frame-core tube structure is discussed in detail to further illustrate the engineering applicability of the proposed method.The analytical investigations demonstrate that the suggested stochastic model of multi-dimensional ground motion is available for accurate seismic response analysis and dynamic reliability assessment of complex engineering structures for performance-based seismic resistance design.
基金the National Key Research&Development Program of China(2016YFB020071)the National Natural Science Foundation of China(Grants 11532016 and 11702315).
文摘The simulation of hypersonic flows with fully unstructured(tetrahedral)grids has severe problems with respect to the prediction of stagnation region heating,due to the random face orientation without alignment to the bow shock.To improve the accuracy of aero-heating predictions,three multi-dimensional approaches on unstructured grids are coupled in our Reynolds-averaged Navier-Stokes(RANS)solver,including multi-dimensional upwind flux reconstruction(MUP),multi-dimensional limiter(MLP-u2)and multi-dimensional gradient reconstruction(MLR).The coupled multi-dimensional RANS solver is validated by several typical verification and validation(V&V)cases,including hypersonic flows over a cylinder,a blunt biconic,and a double-ellipsoid,with commonly used prism/tetrahedral hybrid grids.Finally,the coupled multi-dimensional solver is applied to simulating the heat flux distribution over a 3D engineering configuration,i.e.a Hermes-like space shuttle model.The obtained numerical results are compared with experimental data.The predicted results demonstrate that the coupled multi-dimensional approach has a good prediction capability on aerodynamic heating over a wide range of complex engineering configurations.
基金Sponsored by the National Natural Science Foundation of China (10671116,10871199, and 10001023)Hou Yingdong Fellowship (81004), The China Scholarship Council, Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry, Natural Science Foundation of Guangdong (06027210 and 000804)Natural Science Foundation of Guangdong Education Bureau (200030)
文摘In this article, we get non-selfsimilar elementary waves of the conservation laws in another kind of view, which is different from the usual self-similar transformation. The solution has different global structure. This article is divided into three parts. The first part is introduction. In the second part, we discuss non-selfsimilar elementary waves and their interactions of a class of twodimensional conservation laws. In this case, we consider the case that the initial discontinuity is parabola with u＋ 〉 0, while explicit non-selfsirnilar rarefaction wave can be obtained. In the second part, we consider the solution structure of case u＋ 〈 0. The new solution structures are obtained by the interactions between different elementary waves, and will continue to interact with other states. Global solutions would be very different from the situation of one dimension.
基金supported by the Fundamental Research Funds for the Central Universities,China(buctrc202029,buctrc202129)the Beijing Nova Program(Z211100002121093)。
文摘Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers from dendrite problems.Functional carbon materials(FCMs)have demonstrated their great potential in suppressing metal dendrites benefitting from the multiple merits such as chemical tunability and capability of multi-dimensional structure assembly.Here,we initiate a review to present the recent progress in employing FCMs to deal with dendrite problems.It focuses on the surface chemistry and multi-dimensional carbon material engineering,which systematically overcomes the problems through diverse methods,such as reinforcing desolvation,improving interface compatibility,homogenizing electric field,buffering volume expansion and lattice mismatch.In addition,we also refine the long-standing debate about whether surface defects in FCMs are beneficial to suppress the metal dendrites or not,especially in the non-aqueous electrolyte regime.Finally,the remaining challenges for utilizing FCMs to suppress metal dendrites and the possible solutions are proposed to guide the future development.
基金Projects(51422507,51379168)supported by the National Natural Science Foundation of China
文摘A new kind of multi-dimensional WC-10Co4Cr coating which is composed of nano,submicron,micron WC grains and CoCr alloy,was developed by high velocity oxy-fuel(HVOF)spraying.Porosity,microhardness,fracture toughness and cavitation erosion resistance of the multi-dimensional coating were investigated in comparison with the bimodal and nanostructured WC?10Co4Cr coatings.Moreover,the cavitation erosion behavior and mechanism of the multi-dimensional coating were explored.Results show that HVOF sprayed multi-dimensional WC-10Co4Cr coating possesses low porosity(≤0.32%)and high fracture toughness without obvious nano WC decarburization during spraying.Furthermore,it is discovered that the multi-dimensional WC-10Co4Cr coating exhibits the best cavitation erosion resistance which is enhanced by approximately 28%and 34%,respectively,compared with the nanostructured and bimodal coatings in fresh water.The superior cavitation resistance of multi-dimensional WC-10Co4Cr coating may originate from the unique micro?nano structure and excellent properties,which can effectively obstruct the formation and propagation of cavitation erosion cracks.
基金supported in part by the NSFC(Grant No.11471332)The research of Gao-wei Cao was supported in part by the NSFC(Grant No.11701551).
文摘For the two-dimensional(2D)scalar conservation law,when the initial data contain two different constant states and the initial discontinuous curve is a general curve,then complex structures of wave interactions will be generated.In this paper,by proposing and investigating the plus envelope,the minus envelope,and the mixed envelope of 2D non-selfsimilar rarefaction wave surfaces,we obtain and the prove the new structures and classifications of interactions between the 2D non-selfsimilar shock wave and the rarefaction wave.For the cases of the plus envelope and the minus envelope,we get and prove the necessary and sufficient criterion to judge these two envelopes and correspondingly get more general new structures of 2D solutions.
基金financially supported by the National Natural Science Foundation of China(Nos.52425408 and 52304345)the Fundamental Research Funds for the Central Universities,China(No.2023CDJXY-016)the Postdoctoral Science Foundation of Chongqing(No.CSTB2023NSCQ-BHX0174)。
文摘Currently,the Al_(2)O_(3)content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%,making it challenging to overcome this limitation.Unlike most studies that concentrated on managing the MgO/Al_(2)O_(3)ratio or basicity,this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO-MgO-Al_(2)O_(3)-SiO_(2)slag system,providing theoretical guidance and data to facilitate the application of high-alumina ores.The results revealed that the viscosity first decreased and then increased with higher MgO substitution,reaching a minimum at 15mol%MgO concentration.Fourier transform infrared spectroscopy(FTIR)results found that the depths of the troughs representing[SiO_(4)]tetrahedra,[AlO_(4)]tetrahedra,and Si-O-Al bending became progressively deeper with increased MgO substitution.Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the X_(Q^(3))/X_(Q^(2))(X_(Q^(i))is the molar fraction of Q^(i) unit,and i is the number of bridging oxygens in a[SiO_(4)]tetrahedral unit)ratio increased from 2.30 and 1.02 to 2.52 and 2.14,respectively,indicating a progressive polymerization of the silicate structure.X-ray photoelectron spectroscopy(XPS)results highlighted that non-bridging oxygen content decreased from 77.97mol% to 63.41mol% with increasing MgO concentration,whereas bridging oxygen and free oxygen contents increased.Structural analysis demonstrated a gradual increase in the polymerization degree of the tetrahedral structure with the increase in MgO substitution.However,bond strength is another important factor affecting the slag viscosity.The occurrence of a viscosity minimum can be attributed to the complex evolution of bond strengths of non-bridging oxygens generated during depolymerization of the[SiO_(4)]and[AlO_(4)]tetrahedral structures by CaO and MgO.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51972039,51803018,and 51661145025)LiaoNing Revitalization Talents Program(No.XLYC1902122).
文摘Recently,multilevel structural carbon aerogels are deemed as attractive candidates for microwave absorbing materials.Nevertheless,excessive stack and agglomeration for low-dimension carbon nanomaterials inducing impedance mismatch are significant challenges.Herein,the delicate“3D helix-2D sheet-1D fiber-0D dot”hierarchical aerogels have been successfully synthesized,for the first time,by sequential processes of hydrothermal self-assembly and in-situ chemical vapor deposition method.Particularly,the graphene sheets are uniformly intercalated by 3D helical carbon nanocoils,which give a feasible solution to the mentioned problem and endows the as-obtained aerogel with abundant porous structures and better dielectric properties.Moreover,by adjusting the content of 0D core-shell structured particles and the parameters for growth of the 1D carbon nanofibers,tunable electromagnetic properties and excellent impedance matching are achieved,which plays a vital role in the microwave absorption performance.As expected,the optimized aerogels harvest excellent performance,including broad effective bandwidth and strong reflection loss at low filling ratio and thin thickness.This work gives valuable guidance and inspiration for the design of hierarchical materials comprised of dimensional gradient structures,which holds great application potential for electromagnetic wave attenuation.
