The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large de...The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large deformation during the LCR process and to minimize the thickness of the slab in bending segments,the maximum theoretical reduction amount and the corresponding reduction scheme for the LCR process must be determined.With SPA-H weathering steel as a specific research steel grade,the distributions of tem-perature and deformation fields of a slab with the LCR process were analyzed using a three-dimensional thermal-mechanical finite ele-ment model.High-temperature tensile tests were designed to determine the critical strain of corner crack propagation and intermediate crack initiation with various strain rates and temperatures,and a prediction model of the critical strain for two typical cracks,combining the effects of strain rate and temperature,was proposed by incorporating the Zener-Hollomon parameter.The crack risks with different LCR schemes were calculated using the crack risk prediction model,and the maximum theoretical reduction amount for the SPA-H slab with a transverse section of 145 mm×1600 mm was 41.8 mm,with corresponding reduction amounts for Segment 0 to Segment 4 of 15.8,7.3,6.5,6.4,and 5.8 mm,respectively.展开更多
To recover the valuable elements in Bayan Obo tailings,Fe-Si bath smelting reduction was adopted to separate and enrich rare earth elements(REE),niobium and titanium from the REE-Nb-Ti-containing slag.The reduction re...To recover the valuable elements in Bayan Obo tailings,Fe-Si bath smelting reduction was adopted to separate and enrich rare earth elements(REE),niobium and titanium from the REE-Nb-Ti-containing slag.The reduction reaction process of the Fe-Si bath and the migration behavior of valuable elements in the solidification and crystallization process of silicothermic reduction tailings were investigated,and a treatment method for efficiently separating and enriching REE,Nb and Ti was explored.Thermodynamic analysis indicated that at 1600℃,with a 6 wt.%addition of Si as the reducing agent,the niobium oxide in the REE-Nb-Ti-containing slag could be selectively reduced to metallic Nb.In the Fe-Si bath reduction process,the Nb mass fraction in the metal phase increased with prolonged reaction time,peaking at 2.77%,while the Ti mass fraction consistently stayed below 0.12%.Lowering the w(CaO)/w(SiO_(2))enhanced the migration of Nb from slag to metal phase and reduced the Ti impurities.During solidification and crystallization,a significant quantity of perovskite precipitated from reduction tailings,with the REE dissolving into this perovskite.By adjusting the w(CaO)/w(SiO_(2))in tailings to 1.2-1.9 and maintaining a temperature of 1100℃for 4 h,the perovskite area fraction in the final slag could exceed 37%.Finally,a method was proposed to separate and enrich valuable elements in REE-Nb-Ti-containing slags via Fe-Si bath smelting reduction and crystallization control.展开更多
Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from...Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from a Chinese steel plant was studied in the gas mixtures of CO and N_(2).The results showed the reduction process is divided into two stages.The reduction in the initial stage(time t≤40 min)is cooperatively controlled by internal diffusion and interface chemical reactions with the activation energy of 30.19 and 16.67 kJ/mol,respectively.The controlling step of the reduction in the final stage(t>40 min)is internal diffusion with the activation energy of 34.60 kJ/mol.The reduction process can be described by two equations obtained from kinetic calculations.The reduction degree can be predicted under different temperatures and time,and the predicted results showed an excellent correlation with the experimental results.The reduction mechanisms were confirmed by the analysis of the scanning electron microscope equipped with an energy dispersive spectrometer and optical microscope.展开更多
Electrochemical nitrate reduction(eNO_(3)RR)and nitric oxide reduction(eNORR)to ammonia have emerged as promising and sustainable alternatives to the traditional Haber-Bosch method for ammonia production,particularly ...Electrochemical nitrate reduction(eNO_(3)RR)and nitric oxide reduction(eNORR)to ammonia have emerged as promising and sustainable alternatives to the traditional Haber-Bosch method for ammonia production,particularly within the recently proposed reverse artificial nitrogen cycle route:N_(2)→NO_(x)→NH_(3).Notably,experimental studies have demonstrated that eNORR exhibits superior performance over eNO_(3)RR on Cu6Sn5 catalysts.However,the fundamental mechanisms underlying this difference remain poorly understood.Herein,we performed systematic theoretical calculations to explore the reaction pathways,electronic structure effects,and potential-dependent Faradic efficiency associated with ammonia production via these two distinct electrochemical pathways(eNORR and eNO_(3)RR)on Cu6Sn5.By implementing an advanced‘adaptive electric field controlled constant potential(EFC-CP)’methodology combined with microkinetic modeling,we successfully reproduced the experimental observations and identified the key factors affecting ammonia production in both reaction pathways.It was found that eNORR outperforms eNO_(3)RR because it circumvents the ^(*)NO_(2) dissociation and ^(*)NO_(2) desorption steps,leading to distinct surface coverage of key intermediates between the two pathways.Furthermore,the reaction rates were found to exhibit a pronounced dependence on the surface coverage of ^(*)NO in eNORR and ^(*)NO_(2) in eNO_(3)RR.Specifically,the facile desorption of ^(*)NO_(2) on the Cu6Sn5 surface in eNO_(3)RR limits the attainable surface coverage of ^(*)NO,thereby impeding its performance.In contrast,the eNORR can maintain a high surface coverage of adsorbed ^(*)NO species,contributing to its enhanced ammonia production performance.These fundamental insights provide valuable guidance for the rational design of catalysts and the optimization of reaction routes,facilitating the development of more efficient,sustainable,and scalable techniques for ammonia production.展开更多
Long-bone fractures are common complaints in orthopedic surgery.In recent years,significant progress has been made in robot-assisted fracture-reduction techniques.As a key medical device for diverse fracture morpholog...Long-bone fractures are common complaints in orthopedic surgery.In recent years,significant progress has been made in robot-assisted fracture-reduction techniques.As a key medical device for diverse fracture morphologies and sites,the design of the reduction robot has a profound impact on the reduction outcomes.However,existing reduction robots have practical limitations and cannot simultaneously satisfy clinical requirements in terms of workspace,force/torque,and structural stiffness.To overcome these problems,we first analyze the potential placement areas and performance requirements of reduction robots according to clinical application scenarios.Subsequently,a 3UPS/S-3P hybrid configuration with decoupled rotational and translational degrees of freedom(DOFs)is proposed,and a kinematic model is derived to achieve the motion characteristics of the remote center of motion(RCM).Furthermore,the structural design of a hybrid reduction robot with an integrated distal clamp and proximal fixator was completed,and a mechanical prototype was constructed.The results of the performance evaluations and static analysis demonstrate that the proposed reduction robot has acceptable workspace,force,and torque performance and excellent structural stiffness.Two clinical case simulations further demonstrated the clinical feasibility of the robot.Finally,preliminary experiments on bone models demonstrated the potential effectiveness of the proposed reduction robot in lower-limb fracture reduction.展开更多
To explain the influence mechanism of MgO on the consolidation and reduction characteristics of roasted iron pellets,the properties and structure of pellets were investigated from multi-dimensions.It indicated that th...To explain the influence mechanism of MgO on the consolidation and reduction characteristics of roasted iron pellets,the properties and structure of pellets were investigated from multi-dimensions.It indicated that the MgO addition decreased the reduction swelling index(RSI)and reduction degree of pellets in both CO and H_(2)atmospheres.During the stepwise reduction process of Fe2O3→Fe3O4→FeO,the reduction behaviour of pellets in CO and H_(2)was similar,while the reduction rate of pellets in H_(2)atmosphere was almost twice as high as that in CO atmosphere.During the stepwise reduction process of FeO→Fe,the RSI of pellets showed a logarithmic increase in CO atmosphere and a linear decrease in H_(2)atmosphere.As investigated by first-principles calculations,C and Fe mainly formed chemical bonds,and the CO reduction process released energy,promoting the formation of iron whiskers.However,H and Fe produced weak physical adsorption,and the H_(2)reduction process was endothermic,inhibiting the generation of iron whiskers.With Mg2+doping in FexO,the nucleation region of iron whiskers expanded in CO reduction process,and the morphology of iron whiskers transformed from“slender”to“stocky,”reducing RSI of the pellets.展开更多
Microwave pre-oxidation and biomass reduction were adopted to enhance the separation of titanium and iron in vanadium-titanium magnetite.The effects of microwave pre-oxidation temperature and time,as well as biomass r...Microwave pre-oxidation and biomass reduction were adopted to enhance the separation of titanium and iron in vanadium-titanium magnetite.The effects of microwave pre-oxidation temperature and time,as well as biomass reduction temperature and time,were investigated.The results showed that the average particle size of vanadium-titanium magnetite decreased,and the specific surface area increased with the increase in pre-oxidation temperature and time.The reaction pathway(Fe_(3-x)TixO_(4)→Fe_(2-x)TixO_(3)→Fe_(2)TiO_(5))was proved in microwave pre-oxidation process.The results of biomass reduction roasting showed that biomass reduction could effectively reduce ferric oxide to metallic iron while Ti was enriched in a solid solution of magnesium anosovite,which was beneficial to the subsequent grinding and acid leaching separation.The combined process of microwave pre-oxidation and biomass reduction achieved a high separation efficiency of titanium and iron in vanadium-titanium magnetite without forming complex titanium minerals.The titanium grade in the vanadium-titanium-rich material was 32.10%,and the recovery rate was 91.51%.The iron grade in the iron concentrate(metallic iron)was 90.90%,the recovery rate was 93.47%,and metallization rate was 93.87%.展开更多
This paper investigates the macroscopic and microscopic characteristics of viscosity reduction and quality improvement of heavy oil in a supercritical water environment through laboratory experiments and testing.The e...This paper investigates the macroscopic and microscopic characteristics of viscosity reduction and quality improvement of heavy oil in a supercritical water environment through laboratory experiments and testing.The effect of three reaction parameters,i.e.reaction temperature,reaction time and oil-water ratio,is analyzed on the product and their correlation with viscosity.The results show that the flow state of heavy oil is significantly improved with a viscosity reduction of 99.4%in average after the reaction in the supercritical water.Excessively high reaction temperature leads to a higher content of resins and asphaltenes,with significantly increasing production of coke.The optimal temperature ranges in 380–420℃.Prolonged reaction time could continuously increase the yield of light oil,but it will also results in the growth of resins and asphaltenes,with the optimal reaction time of 150 min.Reducing the oil-water ratio helps improve the diffusion environment within the reaction system and reduce the content of resins and asphaltenes,but it will increase the cost of heavy oil treatment.An oil-water ratio of 1︰2 is considered as optimum to balance the quality improvement,viscosity reduction and reaction economics.The correlation of the three reaction parameters relative to the oil sample viscosity is ranked as temperature,time and oil-water ratio.Among the four fractions of heavy oil,the viscosity is dominated by asphaltene content,followed by aromatic content and less affected by resins and saturates contents.展开更多
The electrochemical conversion of nitrate,a widespread water pollutant,into valuable ammonia represents a green and decentralized approach to ammonia synthesis.However,the sluggish multielectronproton coupling path an...The electrochemical conversion of nitrate,a widespread water pollutant,into valuable ammonia represents a green and decentralized approach to ammonia synthesis.However,the sluggish multielectronproton coupling path and the low reactive species(nitrate and proton)concentration at the catalyst interface inhibit the efficiency of ammonia production from nitrate reduction reaction(NitRR).Herein,we introduce a novel iron-based tandem catalyst encapsulated by reduced graphene oxide(denoted as Fe-rGO),with a superior ammonia production rate of 47.815 mg h^(-1)mg_(ca)^(t-1)and a high Faraday efficiency(FE)of 96.51%at an applied potential of-0.5 V.It also delivers a robust stability with FE above90%under a current density of 250 mA cm^(-2)for 50 h.In situ X-ray absorption spectroscopy reveals that the FeO_(x)is dynamically translated to Fe~0 site concurrently with the enhancement of the NH_(3)production rate,suggesting the Fe^(0) site as hydrogenation active center.The asymmetric distribution of surface charges of rGO not only enriches nitrate ions at the catalytic interface and promotes the hydrogenation process in NitRR,but also protects the iron species and ensures their stability during electrolysis.The Zn-NO_(3)^(-)battery demonstrates an impressive FE of 88.6%,highlighting its exceptional potential for practical applications.展开更多
The selective reduction of carbon dioxide(CO_(2))into high-value-added chemicals is one of the most effective means to solve the current energy and environmental problems,which could realize the utilization of CO_(2) ...The selective reduction of carbon dioxide(CO_(2))into high-value-added chemicals is one of the most effective means to solve the current energy and environmental problems,which could realize the utilization of CO_(2) and promote the balance of the carbon cycle.Formate is one of the most economical and practical products of all the electrochemical CO_(2) reduction products.Among the many metal-based electrocatalysts that can convert CO_(2) into formate,Sn-based catalysts have received a lot of attention because of their low-cost,non-toxic characteristics and high selectivity for formate.In this article,the most recent development of Sn-based electrocatalysts is comprehensively summarized by giving examples,which are mainly divided into monometallic Sn,alloyed Sn,Sn-based compounds and Sn composite catalysts.Finally,the current performance enhancement strategies and future directions of the field are summarized.展开更多
The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansio...The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansion of strip samples was measured using a linear dilatometer during the staged reduction process at a temperature of 900℃.The existence states of MgO in hematite,magnetite,and wüstite were investigated through thermodynamic calculations.The magnetite strip samples were subjected to oxidizing roasting at 1250℃ for 30 min to produce hematite strip samples.The strip samples with 0.49,1.49,2.49,and 3.49 wt.%MgO were analyzed for length change.It was observed that the sample with 2.49 wt.%MgO exhibited the least significant length change.The lengths of the samples with the initial length being 20 mm before reduction changed during the reduction stages of Fe_(2)O_(3)→Fe_(3)O_(4),Fe_(3)O_(4)→FeO,and FeO→Fe were 615,−25,and−378μm,respectively.The volume expansion of hematite to magnetite was primarily attributed to the crystal transformation.During the reduction stage from wüstite to metallic iron,a substantial contraction occurred,while the slag phase was able to retain its original basic shape.The enclosed areas,as indicated by the expansion change curves of the samples with 0.49,1.49,2.49,and 3.49 wt.%MgO,were measured at 3.76×10^(6),3.23×10^(6),3.05×10^(6),and 3.17×10^(6)μm s,respectively.展开更多
The experiment explored the Fe_(2)O_(3) reduction process with H_(2)/CO mixed gas and confirmed a promoting effect from CO when its volume proportion in mixed gas is 20% at 850℃.The ReaxFF molecular dynamics(MD)simul...The experiment explored the Fe_(2)O_(3) reduction process with H_(2)/CO mixed gas and confirmed a promoting effect from CO when its volume proportion in mixed gas is 20% at 850℃.The ReaxFF molecular dynamics(MD)simulation method was used to observe the reduction process and provide an atomic-level explanation.The accuracy of the parameters used in the simulation was verified by the density functional theory(DFT)calculation.The simulation shows that the initial reduction rate of H_(2) is much faster than that of CO(from 800 to 950℃).As the reduction proceeds,cementite,obtained after CO participates in the reduction at 850℃,will appear on the iron surface.Due to the active properties of C atoms in cementite,they are easy to further react with the O atoms in Fe_(2)O_(3).The generation of internal CO may destroy the dense structure of the surface layer,thereby affecting the overall reduction swelling of Fe_(2)O_(3).However,excess CO is detrimental to the reaction rate,mainly because of the poor thermodynamic conditions of CO in the temperature range and the molecular diffusion capacity is not as good as that of H_(2).Furthermore,the surface structures obtained after H_(2) and CO reduction have been compared,and it was found that the structure obtained by CO reduction has a larger surface area,thus promoting the sub sequent reaction of H_(2).展开更多
Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can in...Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can influence the permeability of burden due to the fine particle size of dust,which results in incomplete reduction reactions during the smelting process.In this paper,silicomanganese dust,graphite powder,and other additives were pressed to form carbon-containing dust briquettes,and the self-reduction process of the dust briquettes was investigated through the isothermal thermogravimetric method with different carbon–oxygen (C/O) molar ratios,contents of fluxing agents,and reduction temperatures.Various reduction kinetic models for dust briquettes at different temperatures were established.The results show that the reaction fraction of the dust briquettes was about 90%at a C/O molar ratio of 1.2 with optimal reduction efficiency.The addition of CaF_(2)contributed to the decrease in the melting point and viscosity of dust briquettes,which increased their reduction rate.As the reduction temperature increased,the reduction rate of dust briquettes increased.The reduction reaction rate of dust briquettes was controlled through gas-phase diffusion.Meanwhile,their reduction process was analyzed kinetically,with the reaction time of 5 min as the dividing line.The apparent activation energies for the two diffusion stages were 56.10 and 100.52 kJ/mol,respectively.The kinetic equations are expressed as[1-(1-f)^(1/3)]^(2)=0.69e^(-56100/(RT))t and [1-(1-f)^(1/3)]^(2)=2.06e^(-100520/(RT))t.展开更多
Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-prot...Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.展开更多
In response to the new mechanism of direct vortex melting reduction of vanadium–titanium magnetite,the reaction control mechanism and the migration regularity of valuable components in the process of direct melting r...In response to the new mechanism of direct vortex melting reduction of vanadium–titanium magnetite,the reaction control mechanism and the migration regularity of valuable components in the process of direct melting reduction were investigated using kinetic empirical equation by fitting and combining with X-ray diffraction,X-ray fluorescence,scanning electron microscopy,energy-dispersive spectrometry,and optical microscopy.The results show that iron reduction is controlled by the mass transfer process of(FeOx)in the slag,while vanadium reduction is controlled by both the mass transfer of(VOx)in the slag and the mass transfer of[V]in the molten iron,and the slag–metal interfacial reaction is the only pathway for vanadium reduction.The reduction of iron and vanadium is an obvious first-order reaction,with activation energy of 101.6051 and 197.416 kJ mol^(−1),respectively.Increasing the vortex rate and reaction temperature is beneficial to improving the reaction rate and reduction efficiency.The mineral phase variation of iron and vanadium in the slag during the reduction process is Fe_(2)O_(3)→Fe_(3)O_(4)/FeV_(2)O_(4)→FeTiO_(3) and FeV_(2)O_(4)→MgV_(2)O_(5);titanium in slag is mainly in the form of Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)and CaTiO_(3).As the reaction time went on,the molar ratio(nTi/nMg)in Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)and the Ti2O_(3) content in the slag gradually went up,while the area proportion of Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)went up and then down,and the porosity of the slag and the grain size of Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)got smaller.展开更多
A novel bidirectional tuned rolling mass damper(Bi-TRMD)device is proposed,and its dynamic character-istics and vibration reduction performance are investigated.The device achieves the performance goal of bidirectiona...A novel bidirectional tuned rolling mass damper(Bi-TRMD)device is proposed,and its dynamic character-istics and vibration reduction performance are investigated.The device achieves the performance goal of bidirectional vibration reduction for a tuned rolling mass damper with a single concave structure.First,the Bi-TRMD device is introduced,and its three-dimensional(3D)mechanical model is established.The motion equations of the model are de-rived using the Gibbs-Appell equation,and a trajectory pre-diction method for the sphere and structure within the model is developed.This method demonstrates that the rolling motion of the sphere around orthogonal axes is nearly indepen-dent within a limited range,enabling the simplification of the 3D model into a two-dimensional(2D)model.The accuracy of this simplification is validated through case analysis.The vibration reduction parameters are optimized using the 2D model and Den Hartog theory,leading to the derivation of mathematical expressions for the optimal frequency ratio and damping ratio.Subsequently,the bidirectional vi-bration reduction performance of the Bi-TRMD is analyzed.The results show that under white noise excitation,the Bi-TRMD achieves a bidirectional peak acceleration reduction rate that is 9.92%and 7.79%higher than that of translational tuned mass dampers(TMD)with the same mass.These findings demonstrate that the proposed Bi-TRMD ef-fectively achieves two-directional vibration reduction with a single concave structure,offering superior vibration reduction performance.展开更多
Electrochemical CO_(2) reduction reaction(CO_(2)RR),driven by renewable energy,offers a promising solution to mitigate increasing CO_(2) emissions and establish a carbon-neutral cycle.Copper is a highly selective and ...Electrochemical CO_(2) reduction reaction(CO_(2)RR),driven by renewable energy,offers a promising solution to mitigate increasing CO_(2) emissions and establish a carbon-neutral cycle.Copper is a highly selective and active catalyst for CO_(2)RR but suffers from structural reconstruction challenges.Hybrid organic/inorganic materials address these issues by offering customizable compositions and interfaces.Recently,Buonsanti’s team developed hybrid Cu@AlOx nanocrystals with tunable alumina shells via a colloidal atomic layer deposition approach,achieving stable and selective methane production during CO_(2)RR.Mechanistic studies reveal that the alumina shell stabilizes oxidized copper species through Cu^(2+)-O-Al motifs coordinated with AlO_(4) Lewis acid sites,reducing copper dissolution and structural reconstruction.This study provides key insights into the mechanism underlying stabilization,highlighting the critical role of Lewis acidity in preserving the structural integrity of the catalyst.This highlight review aims to inspire the development of other high-performance and stable catalysts through colloidal atomic layer deposition strategies.展开更多
Exploiting non-precious metal catalysts with excellent oxygen reduction reaction(ORR)performance for energy devices is paramount essential for the green and sustainable society development.Herein,low-cost,high-perform...Exploiting non-precious metal catalysts with excellent oxygen reduction reaction(ORR)performance for energy devices is paramount essential for the green and sustainable society development.Herein,low-cost,high-performance biomass-derived ORR catalysts with an asymmetric Fe-N_(3)P configuration was prepared by a simple pyrolysis-etching technique,where carboxymethyl cellulose(CMC)was used as the carbon source,urea and 1,10-phenanthroline iron complex(FePhen)as additives,and Na_(3)PO_(4)as the phosphorus dopant and a pore-forming agent.The CMC-derived FeNPC catalyst displayed a large specific area(BET:1235 m^(2)g^(-1))with atomically dispersed Fe-N_(3)P active sites,which exhibited superior ORR activity and stability in alkaline solution(E_(1/2)=0.90 V vs.RHE)and Zn-air batteries(P_(max)=149 mW cm^(-2))to commercial Pt/C catalyst(E_(1/2)=0.87 V,P_(max)=118 mW cm^(-2))under similar experimental conditions.This work provides a feasible and costeffective route toward highly efficient ORR catalysts and their application to Zn-air batteries for energy conversion.展开更多
Photocatalytic conversion of CO_(2) is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development.Nowadays,polymeric carbon nitride(PCN)has gained widespread application in CO_(2)...Photocatalytic conversion of CO_(2) is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development.Nowadays,polymeric carbon nitride(PCN)has gained widespread application in CO_(2) solar reduction due to its excellent visible light response,suitable conduction band position,and good cost-effectiveness.However,the amorphous nature and low conductivity of PCN limit its photocatalytic efficiency by leading to low carrier concentrations and facile electron–hole recombination during photocatalysis.Addressing this bottleneck,in this study,potassium-doped PCN(KPCN)/copper(Ⅱ)-complexed bipyridine hydroxyquinoline carboxylic acid(Cu(Ⅱ)(bpy)(H_(2)hqc))composite catalysts were synthesized through a multistep microwave heating process.In the composite,the formation of an S-scheme junction facilitates the enrichment of more negative electrons on the conduction band of KPCN via intermolecular electron–hole recombination between Cu(Ⅱ)(bpy)(H_(2)hqc)(CuPyQc)and KPCN,thereby promoting efficient photoreduction of CO_(2) to CO.Microwave heating enhances the amidation reaction between these two components,achieving the immobilization of homogeneous molecular catalysts and forming amidation chemical bonds that serve as key channels for the S-scheme charge transfer.This work not only presents a new PCN-based catalytic system for CO_(2) reduction applications,but also offers a novel microwave-practical approach for immobilizing homogeneous catalysts.展开更多
Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This ...Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).展开更多
基金supported by the National Natural Science Foundation of China(No.52474355)the Liaoning Province Science and Technology Plan Joint Program(Key Research and Development Program Project),China(Nos.2022JH25/10200003 and 2023JH2/101800058).
文摘The application of liquid core reduction(LCR)technology in thin slab continuous casting can refine the internal microstruc-tures of slabs and improve their production efficiency.To avoid crack risks caused by large deformation during the LCR process and to minimize the thickness of the slab in bending segments,the maximum theoretical reduction amount and the corresponding reduction scheme for the LCR process must be determined.With SPA-H weathering steel as a specific research steel grade,the distributions of tem-perature and deformation fields of a slab with the LCR process were analyzed using a three-dimensional thermal-mechanical finite ele-ment model.High-temperature tensile tests were designed to determine the critical strain of corner crack propagation and intermediate crack initiation with various strain rates and temperatures,and a prediction model of the critical strain for two typical cracks,combining the effects of strain rate and temperature,was proposed by incorporating the Zener-Hollomon parameter.The crack risks with different LCR schemes were calculated using the crack risk prediction model,and the maximum theoretical reduction amount for the SPA-H slab with a transverse section of 145 mm×1600 mm was 41.8 mm,with corresponding reduction amounts for Segment 0 to Segment 4 of 15.8,7.3,6.5,6.4,and 5.8 mm,respectively.
基金supported by the National Key R&D Program of China(No.2021YFC2901200)National Natural Science Foundation of China(Nos.52174383 and 52374412)Liaoning Provincial Natural Science Foundation of China(No.2022-YQ-09).
文摘To recover the valuable elements in Bayan Obo tailings,Fe-Si bath smelting reduction was adopted to separate and enrich rare earth elements(REE),niobium and titanium from the REE-Nb-Ti-containing slag.The reduction reaction process of the Fe-Si bath and the migration behavior of valuable elements in the solidification and crystallization process of silicothermic reduction tailings were investigated,and a treatment method for efficiently separating and enriching REE,Nb and Ti was explored.Thermodynamic analysis indicated that at 1600℃,with a 6 wt.%addition of Si as the reducing agent,the niobium oxide in the REE-Nb-Ti-containing slag could be selectively reduced to metallic Nb.In the Fe-Si bath reduction process,the Nb mass fraction in the metal phase increased with prolonged reaction time,peaking at 2.77%,while the Ti mass fraction consistently stayed below 0.12%.Lowering the w(CaO)/w(SiO_(2))enhanced the migration of Nb from slag to metal phase and reduced the Ti impurities.During solidification and crystallization,a significant quantity of perovskite precipitated from reduction tailings,with the REE dissolving into this perovskite.By adjusting the w(CaO)/w(SiO_(2))in tailings to 1.2-1.9 and maintaining a temperature of 1100℃for 4 h,the perovskite area fraction in the final slag could exceed 37%.Finally,a method was proposed to separate and enrich valuable elements in REE-Nb-Ti-containing slags via Fe-Si bath smelting reduction and crystallization control.
基金support from the National Natural Science Foundation of China(No.52174300)Natural Science Foundation of Chongqing,China(Nos.cstc2020jcyj-msxmX0583 and cstc2021jcyj-msxmX1004)+1 种基金Chongqing Talent Plan Project(No.cstc2021ycjh-bgzxm0211)Chongqing Doctoral"Through Train"Project(No.sl202100000343).T。
文摘Iron ore pellets,as one of the main charges of blast furnaces,have a greater impact on the CO_(2)emission reduction and stable operation of blast furnaces.The isothermal reduction behavior of the pellets obtained from a Chinese steel plant was studied in the gas mixtures of CO and N_(2).The results showed the reduction process is divided into two stages.The reduction in the initial stage(time t≤40 min)is cooperatively controlled by internal diffusion and interface chemical reactions with the activation energy of 30.19 and 16.67 kJ/mol,respectively.The controlling step of the reduction in the final stage(t>40 min)is internal diffusion with the activation energy of 34.60 kJ/mol.The reduction process can be described by two equations obtained from kinetic calculations.The reduction degree can be predicted under different temperatures and time,and the predicted results showed an excellent correlation with the experimental results.The reduction mechanisms were confirmed by the analysis of the scanning electron microscope equipped with an energy dispersive spectrometer and optical microscope.
文摘Electrochemical nitrate reduction(eNO_(3)RR)and nitric oxide reduction(eNORR)to ammonia have emerged as promising and sustainable alternatives to the traditional Haber-Bosch method for ammonia production,particularly within the recently proposed reverse artificial nitrogen cycle route:N_(2)→NO_(x)→NH_(3).Notably,experimental studies have demonstrated that eNORR exhibits superior performance over eNO_(3)RR on Cu6Sn5 catalysts.However,the fundamental mechanisms underlying this difference remain poorly understood.Herein,we performed systematic theoretical calculations to explore the reaction pathways,electronic structure effects,and potential-dependent Faradic efficiency associated with ammonia production via these two distinct electrochemical pathways(eNORR and eNO_(3)RR)on Cu6Sn5.By implementing an advanced‘adaptive electric field controlled constant potential(EFC-CP)’methodology combined with microkinetic modeling,we successfully reproduced the experimental observations and identified the key factors affecting ammonia production in both reaction pathways.It was found that eNORR outperforms eNO_(3)RR because it circumvents the ^(*)NO_(2) dissociation and ^(*)NO_(2) desorption steps,leading to distinct surface coverage of key intermediates between the two pathways.Furthermore,the reaction rates were found to exhibit a pronounced dependence on the surface coverage of ^(*)NO in eNORR and ^(*)NO_(2) in eNO_(3)RR.Specifically,the facile desorption of ^(*)NO_(2) on the Cu6Sn5 surface in eNO_(3)RR limits the attainable surface coverage of ^(*)NO,thereby impeding its performance.In contrast,the eNORR can maintain a high surface coverage of adsorbed ^(*)NO species,contributing to its enhanced ammonia production performance.These fundamental insights provide valuable guidance for the rational design of catalysts and the optimization of reaction routes,facilitating the development of more efficient,sustainable,and scalable techniques for ammonia production.
基金Supported by National Natural Science Foundation of China(Grant Nos.52405001,52175001,62373010,82472537)China Postdoctoral Science Foundation(Grant No.2024M760166)+2 种基金Postdoctoral Fellowship Program of CPSF(Grant No.GZC20230186)Shenzhen Municipal Science,Technology,and Innovation Commission(Grant No.SGDX20220530111005036)Beijing Natural Science Foundation(Grant Nos.3222002,3232004,L222061).
文摘Long-bone fractures are common complaints in orthopedic surgery.In recent years,significant progress has been made in robot-assisted fracture-reduction techniques.As a key medical device for diverse fracture morphologies and sites,the design of the reduction robot has a profound impact on the reduction outcomes.However,existing reduction robots have practical limitations and cannot simultaneously satisfy clinical requirements in terms of workspace,force/torque,and structural stiffness.To overcome these problems,we first analyze the potential placement areas and performance requirements of reduction robots according to clinical application scenarios.Subsequently,a 3UPS/S-3P hybrid configuration with decoupled rotational and translational degrees of freedom(DOFs)is proposed,and a kinematic model is derived to achieve the motion characteristics of the remote center of motion(RCM).Furthermore,the structural design of a hybrid reduction robot with an integrated distal clamp and proximal fixator was completed,and a mechanical prototype was constructed.The results of the performance evaluations and static analysis demonstrate that the proposed reduction robot has acceptable workspace,force,and torque performance and excellent structural stiffness.Two clinical case simulations further demonstrated the clinical feasibility of the robot.Finally,preliminary experiments on bone models demonstrated the potential effectiveness of the proposed reduction robot in lower-limb fracture reduction.
基金support from the National Natural Science Foundation of China(52174290).
文摘To explain the influence mechanism of MgO on the consolidation and reduction characteristics of roasted iron pellets,the properties and structure of pellets were investigated from multi-dimensions.It indicated that the MgO addition decreased the reduction swelling index(RSI)and reduction degree of pellets in both CO and H_(2)atmospheres.During the stepwise reduction process of Fe2O3→Fe3O4→FeO,the reduction behaviour of pellets in CO and H_(2)was similar,while the reduction rate of pellets in H_(2)atmosphere was almost twice as high as that in CO atmosphere.During the stepwise reduction process of FeO→Fe,the RSI of pellets showed a logarithmic increase in CO atmosphere and a linear decrease in H_(2)atmosphere.As investigated by first-principles calculations,C and Fe mainly formed chemical bonds,and the CO reduction process released energy,promoting the formation of iron whiskers.However,H and Fe produced weak physical adsorption,and the H_(2)reduction process was endothermic,inhibiting the generation of iron whiskers.With Mg2+doping in FexO,the nucleation region of iron whiskers expanded in CO reduction process,and the morphology of iron whiskers transformed from“slender”to“stocky,”reducing RSI of the pellets.
基金This work was financially supported by the Hunan Province Key Research and Development Project(2023SK2079)and“Xiaohe”Young Talent Innovation Project in Changsha in 2023.
文摘Microwave pre-oxidation and biomass reduction were adopted to enhance the separation of titanium and iron in vanadium-titanium magnetite.The effects of microwave pre-oxidation temperature and time,as well as biomass reduction temperature and time,were investigated.The results showed that the average particle size of vanadium-titanium magnetite decreased,and the specific surface area increased with the increase in pre-oxidation temperature and time.The reaction pathway(Fe_(3-x)TixO_(4)→Fe_(2-x)TixO_(3)→Fe_(2)TiO_(5))was proved in microwave pre-oxidation process.The results of biomass reduction roasting showed that biomass reduction could effectively reduce ferric oxide to metallic iron while Ti was enriched in a solid solution of magnesium anosovite,which was beneficial to the subsequent grinding and acid leaching separation.The combined process of microwave pre-oxidation and biomass reduction achieved a high separation efficiency of titanium and iron in vanadium-titanium magnetite without forming complex titanium minerals.The titanium grade in the vanadium-titanium-rich material was 32.10%,and the recovery rate was 91.51%.The iron grade in the iron concentrate(metallic iron)was 90.90%,the recovery rate was 93.47%,and metallization rate was 93.87%.
基金Supported by the Foundation for Innovative Research Groups of National Natural Science Foundation of China(52421002)General Program of National Natural Science Foundation of China(52474016).
文摘This paper investigates the macroscopic and microscopic characteristics of viscosity reduction and quality improvement of heavy oil in a supercritical water environment through laboratory experiments and testing.The effect of three reaction parameters,i.e.reaction temperature,reaction time and oil-water ratio,is analyzed on the product and their correlation with viscosity.The results show that the flow state of heavy oil is significantly improved with a viscosity reduction of 99.4%in average after the reaction in the supercritical water.Excessively high reaction temperature leads to a higher content of resins and asphaltenes,with significantly increasing production of coke.The optimal temperature ranges in 380–420℃.Prolonged reaction time could continuously increase the yield of light oil,but it will also results in the growth of resins and asphaltenes,with the optimal reaction time of 150 min.Reducing the oil-water ratio helps improve the diffusion environment within the reaction system and reduce the content of resins and asphaltenes,but it will increase the cost of heavy oil treatment.An oil-water ratio of 1︰2 is considered as optimum to balance the quality improvement,viscosity reduction and reaction economics.The correlation of the three reaction parameters relative to the oil sample viscosity is ranked as temperature,time and oil-water ratio.Among the four fractions of heavy oil,the viscosity is dominated by asphaltene content,followed by aromatic content and less affected by resins and saturates contents.
基金supported by the National Natural Science Foundation of China(12205300(H.S.),12405377(M.H.L))the Postdoctoral Science Foundation of China(2024M763694(M.H.L))+3 种基金the Natural Science Foundation of Hunan Province(2024JJ4027(H.S.))the Postdoctoral Fellowship Program of CPSF under Grant Number GZB20240859(M.H.L)financial support from the Hunan Normal University Program(grant05311204666)financial support from the 2024 Large Instrument Testing Open Fund of Hunan Normal University(24CSY033,24CSY086)。
文摘The electrochemical conversion of nitrate,a widespread water pollutant,into valuable ammonia represents a green and decentralized approach to ammonia synthesis.However,the sluggish multielectronproton coupling path and the low reactive species(nitrate and proton)concentration at the catalyst interface inhibit the efficiency of ammonia production from nitrate reduction reaction(NitRR).Herein,we introduce a novel iron-based tandem catalyst encapsulated by reduced graphene oxide(denoted as Fe-rGO),with a superior ammonia production rate of 47.815 mg h^(-1)mg_(ca)^(t-1)and a high Faraday efficiency(FE)of 96.51%at an applied potential of-0.5 V.It also delivers a robust stability with FE above90%under a current density of 250 mA cm^(-2)for 50 h.In situ X-ray absorption spectroscopy reveals that the FeO_(x)is dynamically translated to Fe~0 site concurrently with the enhancement of the NH_(3)production rate,suggesting the Fe^(0) site as hydrogenation active center.The asymmetric distribution of surface charges of rGO not only enriches nitrate ions at the catalytic interface and promotes the hydrogenation process in NitRR,but also protects the iron species and ensures their stability during electrolysis.The Zn-NO_(3)^(-)battery demonstrates an impressive FE of 88.6%,highlighting its exceptional potential for practical applications.
基金Project(52204378)supported by the National Natural Science Foundation of China。
文摘The selective reduction of carbon dioxide(CO_(2))into high-value-added chemicals is one of the most effective means to solve the current energy and environmental problems,which could realize the utilization of CO_(2) and promote the balance of the carbon cycle.Formate is one of the most economical and practical products of all the electrochemical CO_(2) reduction products.Among the many metal-based electrocatalysts that can convert CO_(2) into formate,Sn-based catalysts have received a lot of attention because of their low-cost,non-toxic characteristics and high selectivity for formate.In this article,the most recent development of Sn-based electrocatalysts is comprehensively summarized by giving examples,which are mainly divided into monometallic Sn,alloyed Sn,Sn-based compounds and Sn composite catalysts.Finally,the current performance enhancement strategies and future directions of the field are summarized.
基金support from the 2023 Basic Research Foundation Project for Universities in the Inner Mongolia Autonomous Region(Grant No.2023RCTD006)the National Natural Science Foundation of China(Grant No.51864041,51664044).
文摘The significant effect of MgO in inhibiting the reduction swelling of iron ore pellets has been widely recognized.The swelling behaviors of pellets during the stepwise reduction by CO were assessed.The linear expansion of strip samples was measured using a linear dilatometer during the staged reduction process at a temperature of 900℃.The existence states of MgO in hematite,magnetite,and wüstite were investigated through thermodynamic calculations.The magnetite strip samples were subjected to oxidizing roasting at 1250℃ for 30 min to produce hematite strip samples.The strip samples with 0.49,1.49,2.49,and 3.49 wt.%MgO were analyzed for length change.It was observed that the sample with 2.49 wt.%MgO exhibited the least significant length change.The lengths of the samples with the initial length being 20 mm before reduction changed during the reduction stages of Fe_(2)O_(3)→Fe_(3)O_(4),Fe_(3)O_(4)→FeO,and FeO→Fe were 615,−25,and−378μm,respectively.The volume expansion of hematite to magnetite was primarily attributed to the crystal transformation.During the reduction stage from wüstite to metallic iron,a substantial contraction occurred,while the slag phase was able to retain its original basic shape.The enclosed areas,as indicated by the expansion change curves of the samples with 0.49,1.49,2.49,and 3.49 wt.%MgO,were measured at 3.76×10^(6),3.23×10^(6),3.05×10^(6),and 3.17×10^(6)μm s,respectively.
基金financial support from the National Natural Science Foundation of China(Nos.52204335 and 52374319)the National Nature Science Foundation of China(No.52174291)the Central Universities Foundation of China(No.06500170)。
文摘The experiment explored the Fe_(2)O_(3) reduction process with H_(2)/CO mixed gas and confirmed a promoting effect from CO when its volume proportion in mixed gas is 20% at 850℃.The ReaxFF molecular dynamics(MD)simulation method was used to observe the reduction process and provide an atomic-level explanation.The accuracy of the parameters used in the simulation was verified by the density functional theory(DFT)calculation.The simulation shows that the initial reduction rate of H_(2) is much faster than that of CO(from 800 to 950℃).As the reduction proceeds,cementite,obtained after CO participates in the reduction at 850℃,will appear on the iron surface.Due to the active properties of C atoms in cementite,they are easy to further react with the O atoms in Fe_(2)O_(3).The generation of internal CO may destroy the dense structure of the surface layer,thereby affecting the overall reduction swelling of Fe_(2)O_(3).However,excess CO is detrimental to the reaction rate,mainly because of the poor thermodynamic conditions of CO in the temperature range and the molecular diffusion capacity is not as good as that of H_(2).Furthermore,the surface structures obtained after H_(2) and CO reduction have been compared,and it was found that the structure obtained by CO reduction has a larger surface area,thus promoting the sub sequent reaction of H_(2).
基金financially supported by the Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking (No. KF-20-3)Shandong Postdoctoral Science Foundation, China (No. SDCX-ZG-202301014)。
文摘Silicomanganese dust contains large amounts of valuables,such as Si and Mn,which can be used as raw materials for the smelting of silicomanganese.However,the direct addition of dust to the submerged arc furnace can influence the permeability of burden due to the fine particle size of dust,which results in incomplete reduction reactions during the smelting process.In this paper,silicomanganese dust,graphite powder,and other additives were pressed to form carbon-containing dust briquettes,and the self-reduction process of the dust briquettes was investigated through the isothermal thermogravimetric method with different carbon–oxygen (C/O) molar ratios,contents of fluxing agents,and reduction temperatures.Various reduction kinetic models for dust briquettes at different temperatures were established.The results show that the reaction fraction of the dust briquettes was about 90%at a C/O molar ratio of 1.2 with optimal reduction efficiency.The addition of CaF_(2)contributed to the decrease in the melting point and viscosity of dust briquettes,which increased their reduction rate.As the reduction temperature increased,the reduction rate of dust briquettes increased.The reduction reaction rate of dust briquettes was controlled through gas-phase diffusion.Meanwhile,their reduction process was analyzed kinetically,with the reaction time of 5 min as the dividing line.The apparent activation energies for the two diffusion stages were 56.10 and 100.52 kJ/mol,respectively.The kinetic equations are expressed as[1-(1-f)^(1/3)]^(2)=0.69e^(-56100/(RT))t and [1-(1-f)^(1/3)]^(2)=2.06e^(-100520/(RT))t.
文摘Hydrogen evolution reaction(HER)is unavoidable in many electrochemical synthesis systems,such as CO_(2)reduction,N2reduction,and H_(2)O_(2)synthesis.It makes those electrochemical reactions with multiple electron-proton transfers more complex when determining kinetics and mass transfer information.Understanding how HER competes with other electrochemical reduction reactions is crucial for both fundamental studies and system performance improvements.In this study,we employed the oxygen reduction reaction(ORR)as a model reaction to investigate HER competition on a polycrystalline-Au surface,using a rotating ring and disk electrode.It’s proved that water molecules serve as the proton source for ORR in alkaline,neutral,and even acidic electrolytes,and a 4-electron process can be achieved when the overpotential is sufficiently high.The competition from H⁺reduction becomes noticeable at the H⁺concentration higher than 2 mmol L^(–1)and intensi-fies as the H^(+)concentration increases.Based on the electrochemical results,we obtained an equivalent circuit diagram for the ORR system with competition from the H+reduction reaction,showing that these reactions occur in parallel and compete with each other.Electrochemical impedance spectroscopy measurements further confirm this argument.Additionally,we discover that the contribution of H+mass transfer to the total H^(+)reduction current is significant and comparable to the kinetic current.We believe this work will deepen our understanding of HER and its competition in electrochemical reduction systems.
基金supported by the National Natural Science Foundation of China(U1908225)the Fundamental Research Funds for Central Universities(N2225012 and N232405-06).
文摘In response to the new mechanism of direct vortex melting reduction of vanadium–titanium magnetite,the reaction control mechanism and the migration regularity of valuable components in the process of direct melting reduction were investigated using kinetic empirical equation by fitting and combining with X-ray diffraction,X-ray fluorescence,scanning electron microscopy,energy-dispersive spectrometry,and optical microscopy.The results show that iron reduction is controlled by the mass transfer process of(FeOx)in the slag,while vanadium reduction is controlled by both the mass transfer of(VOx)in the slag and the mass transfer of[V]in the molten iron,and the slag–metal interfacial reaction is the only pathway for vanadium reduction.The reduction of iron and vanadium is an obvious first-order reaction,with activation energy of 101.6051 and 197.416 kJ mol^(−1),respectively.Increasing the vortex rate and reaction temperature is beneficial to improving the reaction rate and reduction efficiency.The mineral phase variation of iron and vanadium in the slag during the reduction process is Fe_(2)O_(3)→Fe_(3)O_(4)/FeV_(2)O_(4)→FeTiO_(3) and FeV_(2)O_(4)→MgV_(2)O_(5);titanium in slag is mainly in the form of Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)and CaTiO_(3).As the reaction time went on,the molar ratio(nTi/nMg)in Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)and the Ti2O_(3) content in the slag gradually went up,while the area proportion of Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)went up and then down,and the porosity of the slag and the grain size of Mg_(x)Ti_(3−x)O_(5)(0≤x≤1)got smaller.
基金The National Key Research and Development Pro-gram of China(No.2022YFC3801201)the National Natural Science Foundation of China(No.51921006,52478505)+1 种基金the Natural Science Foundation of Guangdong Province(No.2022A1515010403)Shenzhen Collaborative Innovation Project(No.CJGJZD20220517142401002).
文摘A novel bidirectional tuned rolling mass damper(Bi-TRMD)device is proposed,and its dynamic character-istics and vibration reduction performance are investigated.The device achieves the performance goal of bidirectional vibration reduction for a tuned rolling mass damper with a single concave structure.First,the Bi-TRMD device is introduced,and its three-dimensional(3D)mechanical model is established.The motion equations of the model are de-rived using the Gibbs-Appell equation,and a trajectory pre-diction method for the sphere and structure within the model is developed.This method demonstrates that the rolling motion of the sphere around orthogonal axes is nearly indepen-dent within a limited range,enabling the simplification of the 3D model into a two-dimensional(2D)model.The accuracy of this simplification is validated through case analysis.The vibration reduction parameters are optimized using the 2D model and Den Hartog theory,leading to the derivation of mathematical expressions for the optimal frequency ratio and damping ratio.Subsequently,the bidirectional vi-bration reduction performance of the Bi-TRMD is analyzed.The results show that under white noise excitation,the Bi-TRMD achieves a bidirectional peak acceleration reduction rate that is 9.92%and 7.79%higher than that of translational tuned mass dampers(TMD)with the same mass.These findings demonstrate that the proposed Bi-TRMD ef-fectively achieves two-directional vibration reduction with a single concave structure,offering superior vibration reduction performance.
基金supported by the National Natural Science Foundation of China(No.22101289)Hundred Talents Programs in Chinese Academy of Science,and the Ningbo S&T Innovation 2025 Major Special Program(No.2022Z205).
文摘Electrochemical CO_(2) reduction reaction(CO_(2)RR),driven by renewable energy,offers a promising solution to mitigate increasing CO_(2) emissions and establish a carbon-neutral cycle.Copper is a highly selective and active catalyst for CO_(2)RR but suffers from structural reconstruction challenges.Hybrid organic/inorganic materials address these issues by offering customizable compositions and interfaces.Recently,Buonsanti’s team developed hybrid Cu@AlOx nanocrystals with tunable alumina shells via a colloidal atomic layer deposition approach,achieving stable and selective methane production during CO_(2)RR.Mechanistic studies reveal that the alumina shell stabilizes oxidized copper species through Cu^(2+)-O-Al motifs coordinated with AlO_(4) Lewis acid sites,reducing copper dissolution and structural reconstruction.This study provides key insights into the mechanism underlying stabilization,highlighting the critical role of Lewis acidity in preserving the structural integrity of the catalyst.This highlight review aims to inspire the development of other high-performance and stable catalysts through colloidal atomic layer deposition strategies.
基金supported by the National Natural Science Foundation of China(No.21571062)the Program for Professor of Special Appointment(Eastern Scholar)at the Shanghai Institutions of Higher Learning to JGL,and the Fundamental Research Funds for the Central Universities(No.222201717003)。
文摘Exploiting non-precious metal catalysts with excellent oxygen reduction reaction(ORR)performance for energy devices is paramount essential for the green and sustainable society development.Herein,low-cost,high-performance biomass-derived ORR catalysts with an asymmetric Fe-N_(3)P configuration was prepared by a simple pyrolysis-etching technique,where carboxymethyl cellulose(CMC)was used as the carbon source,urea and 1,10-phenanthroline iron complex(FePhen)as additives,and Na_(3)PO_(4)as the phosphorus dopant and a pore-forming agent.The CMC-derived FeNPC catalyst displayed a large specific area(BET:1235 m^(2)g^(-1))with atomically dispersed Fe-N_(3)P active sites,which exhibited superior ORR activity and stability in alkaline solution(E_(1/2)=0.90 V vs.RHE)and Zn-air batteries(P_(max)=149 mW cm^(-2))to commercial Pt/C catalyst(E_(1/2)=0.87 V,P_(max)=118 mW cm^(-2))under similar experimental conditions.This work provides a feasible and costeffective route toward highly efficient ORR catalysts and their application to Zn-air batteries for energy conversion.
基金supported by the National Natural Science Foundation of China(Nos.22106105 and 22201180)the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-E00015)+2 种基金Shanghai Science and Technology Innovation Program(No.21DZ1206300)the Central Local Science and Technology Development Guidance Fund(No.YDZX20213100003002)Shanghai Science and Technology Commission Program(No.20060502200).
文摘Photocatalytic conversion of CO_(2) is pivotal for mitigating the global greenhouse effect and fostering sustainable energy development.Nowadays,polymeric carbon nitride(PCN)has gained widespread application in CO_(2) solar reduction due to its excellent visible light response,suitable conduction band position,and good cost-effectiveness.However,the amorphous nature and low conductivity of PCN limit its photocatalytic efficiency by leading to low carrier concentrations and facile electron–hole recombination during photocatalysis.Addressing this bottleneck,in this study,potassium-doped PCN(KPCN)/copper(Ⅱ)-complexed bipyridine hydroxyquinoline carboxylic acid(Cu(Ⅱ)(bpy)(H_(2)hqc))composite catalysts were synthesized through a multistep microwave heating process.In the composite,the formation of an S-scheme junction facilitates the enrichment of more negative electrons on the conduction band of KPCN via intermolecular electron–hole recombination between Cu(Ⅱ)(bpy)(H_(2)hqc)(CuPyQc)and KPCN,thereby promoting efficient photoreduction of CO_(2) to CO.Microwave heating enhances the amidation reaction between these two components,achieving the immobilization of homogeneous molecular catalysts and forming amidation chemical bonds that serve as key channels for the S-scheme charge transfer.This work not only presents a new PCN-based catalytic system for CO_(2) reduction applications,but also offers a novel microwave-practical approach for immobilizing homogeneous catalysts.
基金supported by the National Natural Science Foundation of China(No.41977029).
文摘Mining and tailings deposition can cause serious heavy metal(loids)pollution to the surrounding soil environment.Soil microorganisms adapt their metabolism to such conditions,driving alterations in soil function.This study aims to elucidate the response patterns of nitrogen-cycling microorganisms under long-term heavy metal(loids)exposure.The results showed that the diversity and abundance of nitrogen-cyclingmicroorganisms showed negative feedback to heavy metal(loids)concentrations.Denitrifying microorganisms were shown to be the dominant microorganisms with over 60%of relative abundance and a complex community structure including 27 phyla.Further,the key bacterial species in the denitrification process were calculated using a random forest model,where the top three key species(Pseudomonas stutzei,Sphingobium japonicum and Leifsonia rubra)were found to play a prominent role in nitrite reduction.Functional gene analysis and qPCR revealed that nirK,which is involved in nitrite reduction,significantly accumulated in the most metal-rich soil with the increase of absolute abundance of 63.86%.The experimental results confirmed that the activity of nitrite reductase(Nir)encoded by nirK in the soil was increased at high concentrations of heavy metal(loids).Partial least squares-path model identified three potential modes of nitrite reduction processes being stimulated by heavy metal(loids),the most prominent of which contributed to enhanced nirK abundance and soil Nir activity through positive stimulation of key species.The results provide new insights and preliminary evidence on the stimulation of nitrite reduction processes by heavy metal(loids).
