Abstract:Significance The semiconductor industry,as a pillar of the national economy and a strategic cornerstone,is facing new develop-ment opportunities with breakthroughs in third-generation semiconductor technologies.In this process,chip manufacturing pro-cesses and the material supply chain have become the keys to promote industry progress.Refractory metal targets,such as tung-sten(W)and molybdenum(Mo),are indispensable for the manufacturing of semiconductor integrated circuits due to their excellent physical and chemical properties.These materials,prepared as functional thin films through sputtering,are widely applied in several key areas of electronic information industries.However,a significant challenge lies in the low utilization rates of high-purity sputtering targets,typically below 30％for planar targets and under 70％for rotating targets.Consequently,recy-cling and reusing spent targets after sputtering not only have considerable economic benefits but also contribute significantly to environmental protection. Progress This study reviews the current application status of refractory metal targets in the semiconductor industry,analyzes their preparation processes,and predicts future development trends.Refractory metal sputtering targets are generally produced using two major methods:melting technologies and powder metallurgy.Melting technologies such as electron beam melting and arc melting are commonly used for tantalum(Ta)and niobium(Nb)targets,while tungsten(W)and molybdenum(Mo)targets are predominantly prepared through powder metallurgy.Especially for alloys with significant differences in density and melting points,powder metallurgy ensures the uniformity of the target's structure and composition.Methods such as hot pressing(including vacuum and inert gas),hot isostatic pressing,cold isostatic pressing,and spark plasma sintering are commonly used to achieve full densification.Moreover,this study analyzes in detail the influence of key factors such as density,purity,grain size,and crystal orientation on target properties.The use of high-purity powder raw materials is crucial,as impurities can degrade electrical and optical properties,impacting device performance.Current technologies for preparing high-purity refrac-tory metal powders mainly include physical-chemical methods,plasma spheroidization,atomization,and plasma rotating elec-trode methods,with atomization emerging as the mainstream process.This study also explored the recycling and remanufactur-ing technologies for waste targets.High-purity target recovery primarily involves electron beam vacuum remelting or converting spent targets into high-purity powder.However,these methods could increase cost and lead to material loss.In addition,during converting,impurities may be introduced,potentially compromising the purity of remanufactured targets.Compared to the recy-cling process,remanufacturing process,which involves filling etched area with the same material without soldering has minimal material loss,lower costs,and better preservation of target properties.Spark plasma sintering,as an efficient sintering and bonding technique,has been successfully applied in the remanufacturing process of targets such as W,Mo,W-10％Ti,W-30％Si,and Mo-10％Nb. Conclusions and prospects The development of refractory metal targets is expected to focus on the following key areas:1)High purity and high uniformity:As integrated circuit feature sizes shrink,the demand for higher purity and uniformity in targets increases.2)Large size and high flatness:To meet the requirements for processing large-sized silicon wafers,improving the size and surface flatness of targets is crucial.3)Innovation of preparation technology:Continuous improvement and innovation of preparation technologies,such as powder metallurgy,hot pressing,spark plasma sintering,and spray melting,will improve target performance and reduce manufacturing costs.4)Recycling and remanufacturing:Adapting to increasingly strict environ-mental regulations and maximizing cost-effectiveness make recycling and remanufacturing key industry priorities.With growing investments from domestic enterprises and research institutes,China will make great progress in the research and preparation of high-purity refractory metal targets.With these advancements,China will reduce its dependence on imported targets,increase the market share of domestic target materials,and bolster China's electronic materials industry to rival and surpass the levels of developed countries.

Abstract:Objective Raw soil has low strength and poor durability,but it offers advantages such as recyclability,good thermal perfor-mance,and ease of construction.The strength and durability of raw soil can be improved through chemical modification by active materials such as cement,gypsum,lime,and fly ash.The strength of raw soil can be improved through physical modification by recycled aggregates made from crushed and screened waste concrete,bricks,etc.Therefore,to fully utilize raw soil in modem construction industry,lime and fly ash are needed to blend into recycled aggregate-raw soil composite to improve durability. Methods The mass fractions of raw soil,recycled fine aggregates,and recycled coarse aggregates were set at 60％,10％,and 30％,respectively.The mass of water was set to 14％of the total mass of the three raw materials.After mixing the three raw materials,water was added to produce the initial specimen of recycled aggregate-raw soil composite.Chemical modification was carried out by adding different dosages of lime and fly ash,with lime mass fractions set at 6％,7％,7％,8％,and 8％,and fly ash mass fractions set at 12％,12％,13％,13％,and 14％,respectively.Through water resistance,erosion,wet-dry cycling,and freeze-thaw cycling tests,the water resistance,erosion resistance,wet-dry cycling resistance,and freeze-thaw resistance of the recycled aggregate-raw soil composite were analyzed.X-ray diffraction and scanning electron microscopy were used to characterize the hydration products and microstructure of the recycled aggregate-raw soil composite. Results and Discussion With the increase in lime and fly ash dosage,the softening coefficient of the specimens increased,and the water resistance was gradually enhanced.When the lime mass fraction was 8％and the fly ash mass fraction was 14％,the recycled aggregate-raw soil composite specimen exhibited the highest softening coefficient and the best water resistance.Its erosion resistance was significantly improved with an erosion resistance time of up to 60 minutes.The specimen had the smallest mass loss rate.After 15 wet-dry cycles,both the mass loss rate and compressive strength loss rate were at their minimum values,showing the best resistance to wet-dry cycles.After 25 freeze-thaw cycles,the mass loss rate of the specimen was less than 5％and the compressive strength loss rate was less than 25％,demonstrating the best freeze-thaw resistance of the recycled aggregate-raw soil composite specimen. Conclusion The alkaline effect of lime activates the reactive substances(SiO2,Al2O3)in the raw soil,fly ash,and recycled micro powder,participating in the hydration reactions to generate C-S-H gel,C-A-S-H gel,Ca(OH)2 crystals,and calcium vanadate crystals.These hydration products fill the cracks and pores within the recycled aggregate-raw soil composite,enhanc-ing the adhesion between the particles and improving the durability of the recycled aggregate-raw soil composite.

Abstract:Significance Concrete,a dominant construction material,often fails to achieve its designed service life and mechanical strength due to its inherent brittleness,high porosity,and susceptibility to various environmental stressors such as freeze-thaw cycles,chemical attacks,and moisture ingress.These constraints have driven continuous research on improving its durability and per-formance.Among various modification techniques,the incorporation of polymers into cement-based materials has emerged as a promising solution.Polymers,serving as organic additives,can significantly enhance concrete's flexibility,bonding proper-ties,and resistance to cracking and degradation.The potential of polymers to improve the mechanical behavior and durability of concrete has attracted increasing interest from both scientific and engineering communities.Polymer-modified concrete systems are being explored for a wide range of applications,including infrastructure development,road and bridge construction,marine structures,and the rehabilitation and repair of aging facilities.A comprehensive understanding of how polymers affect the rheol-ogy,strength development,and long-term performance of concrete is essential for optimizing their use and maximizing their potential in sustainable construction. Progress This paper comprehensively reviews the classification,preparation,and performance characteristics of concrete-polymer composites.It begins by categorizing polymer-concrete systems into four major types:polymer concrete(PC),polymer-impregnated concrete(PIC),polymer-modified concrete(PMC),and newly developed polymer-based composites.Each type exhibits unique features in terms of composition,preparation methods,and applications.For instance,PC is a composite where polymer resin entirely replaces traditional cement as the binder,achieving superior strength and chemical resistance.PIC involves the impregnation of hardened concrete with monomers that are then polymerized,enhancing impermeability and durabil-ity.PMC,the most widely used in practical applications,combines polymers with conventional cement paste to improve the overall performance at a relatively low cost.Furthermore,the paper examines how polymers influence workability,hydration behavior,mechanical properties,and durability. Conclusions and Prospects Research findings indicate that both PC and PIC systems provide exceptional mechanical and dura-bility performance.However,their widespread adoption is hindered by challenges such as elevated material costs,energy-intensive curing requirements,and complex fabrication techniques.In comparison,PMC offers a more viable solution for real-world applications due to its ease of implementation and cost-effectiveness.In addition to traditional systems,this review explores the potential of next-generation concrete-polymer composites.These encompass in-situ polymerized systems that achieve high strength but face challenges in reaction control,fiber-reinforced polymer composites that offer excellent toughness but are susceptible to fiber dispersion and dosage,and sustainable alternatives like waste plastic or rubber-modified concrete,which provide environmental benefits but are constrained by limitations in structural performance.Future research should priori-tize addressing the interfacial interactions between polymers and cement hydrates,a critical factor influencing the composite's overall behavior.Moreover,innovation in eco-friendly and recyclable polymer materials is essential for advancing green and sus-tainable construction.Through interdisciplinary approaches that integrate material science,chemistry,and structural engineer-ing,concrete-polymer composites can be further developed to meet the evolving demands of contemporary infrastructure.

Abstract:Significance As an important raw material for additive manufacturing(AM),the quality of metal powder is one of the key fac-tors influencing final product performance.With the rapid development of AM technologies,the demand for high-quality and cost-effective powders has significantly increased.The atomization method,which directly transforms molten metal into powder,is particularly suitable for AM applications.This review introduces the research progress of three typical atomization technolo-gies:gas atomization,plasma rotating electrode process(PREP),and ultrasonic atomization(UA).While gas atomization and PREP have achieved large-scale powder production,UA stands out as the most promising powder preparation technique due to its high powder quality and low production cost. Progress The rising demands for powder quality and cost-efficiency in AM have promoted the development of atomization tech-niques.Research on gas atomization mainly focuses on optimizing the structure of the atomization nozzle and clarifying the impact of key atomization parameters on powder yield and quality.For PREP,three mechanisms of powder formation have been clarified,and the effects of key factors such as equipment layout and rod speed on powder yield and morphology have been estab-lished.Additionally,researchers have explored methods to increase the rod rotational speed and prevent powder contamination.With its high process controllability and low powder preparation cost,UA has attracted significant attention.Various types of UA devices have been developed based on the fundamental principles of UA,although the hourly powder yield remains lower compared to the other two techniques. Conclusions and Prospects Developing atomization technologies for metal powders and upgrading equipment and processes to achieve efficient and low-cost production of high-quality metal powders is a key direction for the future development of atomiza-tion methods.This paper reviews the research progress of three atomization technologies:gas atomization,PREP,and UA.The conclusions are as follows:1)A low yield of fine powders and a high content of defective powders are the primary issues faced by gas atomization.Optimizing the structure of the atomizer to enhance gas kinetic energy efficiency and adjusting the airflow struc-ture within the atomization chamber to avoid the formation of defective powders are crucial for improving powder quality and reducing production costs.2)Consistently increasing the rotational speed of the electrode rod and optimizing the performance of the heat source,material supply,and chamber structure are key to PREP development.3)UA has significant development potential,but its underlying atomization mechanism is more complex.How to optimize equipment and processes to increase pow-der yield is a bottleneck issue that needs to be addressed.

Abstract:Significance In lunar exploration projects,understanding the interactions between lunar probes and lunar soil is essential.This necessitates a thorough investigation into the mechanical properties and constitutive relations of lunar soil.To gain a clearer understanding of these properties and the interactions between soil particles,this paper reviews and summarizes the research progress in the mechanical properties of lunar soil simulants through experimental studies and discrete element method(DEM)simulations.It aims to provide a reference for a deeper understanding of the mechanical and constitutive characteristics of lunar soil,as well as to analyze numerous mechanical problems encountered in lunar exploration. Progress Due to the high-vacuum and low-gravity environment on the moon,lunar soil differs greatly from earth's soil and exhibits unique physical and mechanical properties.However,given the scarcity of real lunar soil samples,lunar soil simulants with similar properties are utilized as substitutes.This paper focuses on the experimental and DEM simulation studies of various lunar soil simulants with different physical properties,examining factors such as tensile strength,shear strength,bearing capac-ity,soil-tool and wheel-soil interactions,and landing impact response.Furthermore,it evaluates the mechanical constitutive models for lunar soil simulants established based on these experiments and DEM simulations.Currently,there is limited research on the dynamic deformation characteristics of lunar soil simulants under vacuum and low-stress conditions,as well as on the damage caused by the failure of glassy cement in the soil.Therefore,conducting systematic and in-depth research on the dynamic deformation and damage evolution of lunar soil simulants is crucial.Understanding their dynamic deformation and dam-age evolution under vacuum and low-stress conditions and establishing a dynamic damage constitutive model for lunar soil under such environments are significant for accurately describing its mechanical properties. Conclusions and Prospects The paper points out the main issues in current research on the mechanical properties of lunar soil through experiments,DEM simulations,and constitutive models.1)Experimental studies mainly focus on the static properties of lunar soil simulants,lacking research on dynamic properties under low-gravity and vacuum environments.This is insufficient for the dynamic data required for large-scale lunar sampling and lunar base construction.2)DEM simulations of the dynamic perfor-mance of lunar soil simulants are rare,and the models often lack the unique structure of glassy cement in real lunar soil and the particle cohesion it causes,making it difficult to accurately reflect the dynamic deformation characteristics of the glassy cement under low-gravity and vacuum environments.3)Most constitutive models are based on existing experimental data of lunar soil simulants under conventional static stress,with almost no dynamic damage constitutive models that consider the deformation mechanisms of lunar soil under low dynamic stress and vacuum environments.Thus,it fails to accurately describe the dynamic performance of lunar soil.Therefore,future research should focus more on the dynamic performance of lunar soil simulants.In addition,for constitutive models,efforts should be made to develop microscopic damage constitutive models based on the defor-mation and damage mechanisms of lunar soil simulants,as well as dynamic constitutive models that integrate machine learning with physical information such as deformation and damage.This will enable a systematic analysis of the dynamic performance of lunar soil simulants and lay a theoretical foundation for addressing related mechanical problems in lunar exploration projects.

Abstract:Significance Advanced oxidation technology has garnered significant scientific and technological interest due to its excellent physical,mechanical,and chemical properties,making it highly promising for applications in water and air pollution treatment.Specifically,photocatalysis and persulfate activation catalysis stand out as highly effective methods for addressing environmental challenges,such as heavy metal ion removal,organic wastewater purification,and degradation of harmful airborne organic com-pounds.These techniques are widely recognized for their simplicity,high efficiency,and cost-effectiveness.However,despite these advantages,limitations remain,such as easy aggregation and instability of catalysts,which hinders the optimization of oxi-dation processes,driving the exploration of alternative catalytic materials.Among all the candidates,diatomite-based compos-ites have emerged as a popular choice for catalyst substrates.Derived from natural minerals,diatomite composites demonstrate excellent stability,high specific surface area,and superior chemical activity,making them a research hotspot in organic waste-water treatment over the past decade.These properties also position them as a transformative solution for enhancing the effi-ciency and sustainability of water treatment processes. Progress In photocatalysis and persulfate activation,various modification methods have been employed to optimize the structure and properties of diatomite composite catalysts.In photocatalysis,diatomite composites typically incorporate bismuth-based semiconductors,TiO2,graphitic carbon nitride(g-C3N4),and metal compounds,synergistically enhancing photocatalytic per-formance.In persulfate activation,diatomite composites primarily serve as a support for metal bases,including cobalt(Co),iron(Fe),manganese(Mn),and cerium(Ce).As a photocatalytic material,diatomite forms an adsorption-photocatalytic col-laborative system,providing abundant active sites,enhancing light absorption,and improving photocatalytic efficiency by inhib-iting electron-hole recombination.As a carrier for bimetallic persulfate activation,diatomite synergizes with various transition metals,preventing metal ion agglomeration and leaching.Its unique interconnected porous structure and oxygen vacancies ensure low charge transport resistance,while creating numerous exposed edges and sharp corners.This structural arrangement significantly expands the material's accessible spaces and increases the number of active edge sites.Additionally,its open diffu-sion channels and abundant hydroxyl groups reduce the migration distance of reactive oxygen species(ROS),enhancing organic pollutant degradation efficiency.Diatomite composites exhibit remarkable degradation performance for various organic pollut-ants,including dyes,pesticides,antibiotics,and endocrine disruptors,achieving degradation rates of over 80％.Moreover,these composites demonstrate excellent recyclability and stability,making them highly suitable for practical applications.Their unique properties also facilitate their separation and recovery from treated water,ensuring sustainability and cost-effectiveness. Conclusions and Prospects Over the past decade,significant progress has been made in diatomite composite catalytic materi-als,unlocking new applications.The incorporation of organic compounds,semiconductors,and metals into diatomite has improved its catalytic efficacy.Future research should focus on exploring synergistic effects in complex catalytic systems,refin-ing diatomite modification methods,optimizing their structure and performance,and leveraging multi-system cooperation pro-cesses.Integrating these composites with other environmental treatment technologies is also crucial.Although laboratory results are promising,maintaining high efficiency in actual applications with complex and variable water environments requires further studies.Moreover,exploring scalable and high-yield preparation methods for industrial production and application remains a key research focus.

Abstract:Significance Hydrogen energy is widely regarded as a promising clean and renewable energy source,but its practical applica-tion is hindered by challenges in efficient and secure storage.Among various hydrogen storage materials,MXene,a type of two-dimensional material,has attracted significant attention due to its adjustable surface chemical properties,structural flexibility,and high specific surface area.This study reviews both theoretical and experimental research on MXene materials for hydrogen storage and explores the factors influencing their storage performance. Progress This paper first examines theoretical studies on hydrogen storage in single-layer and multi-layer MXene structures.Early theoretical research by Hu et al.(2013)used density functional theory(DFT)calculations to evaluate the hydrogen stor-age potential of Ti2C,revealing a hydrogen storage capacity of up to 8.6％under environmental conditions,meeting the target set by the US Department of Energy.In 2020,a study introduced a high-throughput screening method to identify promising hydrogen storage materials among two-dimensional nanostructures,pinpointing six ideal candidates,including C-based and B-based structures,with theoretical hydrogen weight densities exceeding 5.5％.This method highlights the importance of balanc-ing adsorption energy,thermodynamic stability,and electronic properties for effective hydrogen capture.A first-principles study in 2024 systematically analyzed how mixed and uniform surface functional groups affect the hydrogen adsorption and stor-age capacity of single-layer Ti3C2Tx.The study investigated various surface functional groups,including O,OH,F,and H,both individually and in combination,and evaluated their effects on hydrogen adsorption energy and capacity.Emphasis was placed on the role of transition metal elements and surface functional groups in optimizing hydrogen adsorption.Another study in 2024 utilized first-principles calculations to investigate the hydrogen adsorption behavior in multi-layer MXenes,with a focus on the effects of interlayer spacing and transition metal elements.The results indicated that interlayer spacing played a crucial role in regulating hydrogen adsorption behavior:a narrower spacing enhanced the adsorption of hydrogen molecules through Kubas-type interactions,while an expanded spacing facilitated the chemical adsorption of hydrogen atoms.At room temperature and 60 bar,multi-layer Ti2C exhibited a hydrogen storage capacity as high as 8.8％,with strong physical adsorption contributing to its excellent performance.These findings highlight the potential of interlayer spacing manipulation in optimizing hydrogen storage and release kinetics.Experimental studies have further demonstrated the potential of MXene for hydrogen storage under low liq-uid nitrogen temperatures and near-room-temperature conditions.A research report in 2024 indicated that multi-layer Ti3C2Txachieved an excellent hydrogen storage capacity of approximately 10.47％at 77 K and 25 bar.Additionally,Shui et al.(2012)prepared partially etched multilayer Ti2CTx,which achieved 8.8％hydrogen absorption at 60 bar near room tempera-ture.The high hydrogen storage capacity was attributed to the unique nano-pump effect promoted by the fluorine surface groups and a narrow interlayer spacing of approximately 7 Å. Conclusions and Prospects Although theoretical studies have predicted various MXene materials with high hydrogen storage potential,only a limited number have been experimentally investigated.There is an urgent need for extensive experimental research to validate and identify MXene materials with excellent hydrogen storage capacities.Combining experimental studies with advanced computational approaches,such as machine learning and high-throughput screening,can accelerate the discov-ery process.Additionally,these techniques offer deeper insights into the relationship between material composition,structure,and storage performance,contributing to a better understanding of MXene hydrogen storage mechanisms.Although the theoreti-cal composition of MXene is well understood,the synthesis process often introduces defects within the layers and on the surface,along with grafted functional groups.Previous studies show that defects and functional groups significantly affect the hydrogen storage capacity of MXene by altering the interaction between hydrogen molecules and MXene surfaces-either enhancing or inhibiting storage performance.Therefore,developing techniques to precisely control and tailor these defects and functional groups is essential for optimizing the hydrogen storage performance of MXene.One key advantage of multi-layer MXene is its ability to store substantial amounts of hydrogen at near-ambient temperatures.Compared to single-layer MXene,the hydrogen storage mechanism in multi-layer MXene is more complex,with interlayer spacing emerging as a key factor.Adjusting the inter-layer spacing directly affects hydrogen adsorption energy,diffusion rate,and hydrogen storage kinetics.Controlling the inter-layer spacing is a crucial strategy for enhancing the hydrogen storage performance of multi-layer MXene.Future research should prioritize developing precise methods for adjusting interlayer spacing,whether through chemical modification or external factors such as pressure and temperature.By optimizing the interlayer spacing,the hydrogen storage density and cycling stability of MXene can be significantly improved,making it highly viable for practical applications.Additionally,further studies are neces-sary to investigate the interactions between interlayer spacing and surface functional groups to understand how these factors col-lectively contribute to the overall hydrogen storage performance of multi-layer MXene.

Abstract:Objective Metal matrix dispersion nuclear fuel elements have garnered widespread attention worldwide.Currently,the metal matrix dispersion fuel elements in use are U-Mo alloy powders or U3Si2 core particles uniformly dispersed within an aluminum(Al)matrix.These fuel elements exhibit favorable thermal conductivity,and the dispersed nature of the fuel allows for efficient heat removal and a higher uranium concentration compared to conventional fuel types.However,in the highly irradiated environ-ment within a reactor,the interface between the fuel core and the external Al matrix is prone to expansion,leading to void forma-tion.This study aims to deposit a uniform Al coating on nuclear fuel particles via the fluidized bed-chemical vapor deposition(FB-CVD)method to enhance the compatibility between the particles and the external Al matrix. Methods Spherical zirconia particles with a diameter of 500 μm were used to simulate uranium dioxide particles.Irregular tung-sten carbide(WC)particles,sized between 50-100 μm,were utilized as the core to simulate irregular U3Si2 cores.The Al coat-ing was prepared using an FB-CVD device with a conical fluidization tube,ensuring uniform coating by moving the particles like a fountain.In the experimental setup,triisobutylaluminum(TIBA)served as the precursor,placed in an evaporation tank out-side the equipment.The TIBA vapor was transported to the fluidized bed by carrier gas,and the Al coating was deposited on par-ticles through the high-temperature decomposition of TIBA.During the experiment,particle fluidization and the precursor depo-sition rate were regulated by adjusting the deposition temperature and carrier gas flow rate,while the precursor transport rate was controlled by modifying its evaporation temperature and carrier gas rate.The effects of various process parameters on the growth of Al coating were studied. Results and Discussion A uniform and durable aluminum coating was achieved by optimizing the precursor carrier gas velocity,reaction temperature,and precursor evaporation temperature.The coated particles showed a metallic luster,with no adhesion between them,indicating good fluidity during the coating process without stagnation in any specific region.A uniform and intact Al coating free from cracking,protrusions,or delamination was formed,and it was well-bonded with the matrix particles.Energy dispersive spectroscopy(EDS)analysis revealed that Al was the main component of the coating,with a growth rate of approximately 2.6 μm/h.Additionally,by co-fluidizing zirconia particles with irregular WC particles,a uniform Al coating on the surface of the irregular particles was realized as the irregular WC particles were driven to form a uniform flow pattern. Conclusion A uniform and dense Al coating was successfully deposited on the surfaces of the spherical zirconia particles and irregular WC particles using TIBA as the precursor via the FB-CVD method.The conclusions are:1)An Al coating preparation system was designed,and stable transport of the TIBA precursor was successfully realized.A stable and durable Al coating was achieved through process parameter optimization.2)The relationship between the growth rate of Al coating and process param-eters was verified.The deposition rate of the Al coating increased with higher reaction temperatures and precursor transport vol-umes,but excessive increases led to undesirable deposition in other areas of the equipment.3)The growth rate of the Al coating was about 2.6 μm/h,and the prepared Al coating exhibited uniform thickness with interior pores.Also,the coating was tightly bonded to the core without gaps or delamination.4)A uniform Al coating on the surface of irregular particles was achieved through the co-fluidization process.

Abstract:Objective To address the growing demands for excitation-free optical temperature sensing in modern engineering and anti-counterfeiting technologies,it is crucial to improve the persistent luminescence and optical temperature-sensing performance of near-infrared(NIR)long persistent luminescence phosphors,broadening their application scenarios. Methods The ZnGa2-x(Mg-Zr)xO4:Cr3+(ZGMZC,x=0-0.2)NIR long persistent luminescence phosphors were synthesized via a high-temperature solid-state method by co-doping Mg2+and Zr4+into ZnGa2O4:Cr3+.A systematic analysis was conducted to investigate the effects of different Mg2+-Zr4+doping amounts on the phase structure,luminescence,and persistent luminescence performance of the ZnGa2O4system.Moreover,the material's potential for temperature sensing under natural light excitation was explored. Results and Discussion The maximum doping amount of Mg2+-Zr4+was 10％.An increase in Mg2+-Zr4+doping content was obser-ved to enlarge the grain size while progressively widening the band gap.After high-temperature calcination,the samples exhib-ited strong capability for visible light absorption.The Mg2+-Zr4+doping facilitated the formation of anti-site defects,thereby increasing defects in the matrix.Consequently,the R-line emission and its Stokes and anti-Stokes phonon sidebands(PSB)gradually weakened in the emitted light,while the N-line emission gradually strengthened.However,excessive doping enhanced energy transfer between Cr3+and defects,which promoted more non-radiative transitions,causing energy loss and weakened luminescence.Furthermore,as the Mg2+-Zr4+doping amount rose,the sample's persistent luminescence initially increased and then decreased,with the x=0.05 sample exhibiting the optimal luminescence performance.Under dark conditions,the NIR per-sistent luminescence of the phosphors was enhanced with increasing temperature. Conclusion The persistent luminescence performance of NIR phosphors is significantly enhanced through Mg2+-Zr4+co-doping.The synthesized materials exhibit temperature-dependent long persistent luminescence characteristics,which can be effectively charged under natural light and subsequently emit NIR light.The properties indicate their potential as natural light rechargeable materials for optical temperature sensing.

Abstract:Objective To prepare ternary geopolymers with excellent mechanical properties and eco-friendly characteristics,this study used metakaolin,fly ash,and coal gangue as raw materials and a phosphate solution as the activator.The simplex centroid design method(SCDM)was used to optimize the dosage ratios of metakaolin,fly ash,and coal gangue. Methods The activity indices of three raw materials,i.e.,metakaolin,fly ash,and coal gangue,were evaluated.Preliminary optimization of their dosage ratios was conducted using SCDM,and the control,single-doped,and co-doped group samples were prepared.The influence of raw material dosage ratios on the mechanical properties,flowability,and pore structure of the samples was analyzed.The mechanism of hydration product formation in ternary geopolymers was revealed through microscopic morphology analysis.The optimal dosage ratios of the three raw materials for preparing ternary geopolymers were determined. Results and Discussion At a curing age of 28 days,the activity indices of metakaolin,fly ash,and coal gangue were measured as 104.2％,85.2％,and 51.1％,respectively.The incorporation of coal gangue resulted in varying degrees of decreases in compressive strength and fluidity of ternary geopolymers,while its effect on flexural strength was negligible.In contrast,the addition of fly ash effectively improved the fluidity and mitigated compressive strength reduction caused by coal gangue.Most co-doped group samples exhibited superior compressive strength and fluidity compared to the control and single-doped group samples.The pore structure analysis revealed that the control group samples primarily contained air pores with a limited number of small capillary pores and gel pores,showing a relatively dense structure.The single-doped group samples exhibited a higher proportion of small capillary pores and air pores.Although the co-doped group samples were still dominated by small capillary pores and air pores,the porosity of small capillary pores was increased to varying degrees,and the number of air pores was reduced compared to single-doped group,indicating an improved pore structure.The phosphate activator was observed to react with precursor materials such as metakaolin and fly ash through geopolymerization,forming amorphous gels,including phospho-aluminate gels[—Al—O—P—]n and aluminosilicate hydrate gels[—Si—O—Al—O—P—]n.These gels greatly enhanced the mechanical properties of geopolymers.To achieve a balance between mechanical properties,fluidity,and economic efficiency,at a curing age of 28 days,the compressive and flexural strengths of ternary geopolymers were set to be no less than 60％of the control group.Under the condition of compressive strength is equal or more than 45.0 MPa,flexural strength is equal or more than 5.8 MPa,and fluidity is more than 180 mm,the optimal mass fractions of each raw material in the optimized dosage were determined as follows:metakaolin 74％～83％,fly ash 3％～15％,and coal gangue 15％～27％. Conclusion Using SCDM,the optimal dosage of raw materials in ternary geopolymer mortar is achieved,striking a balance between mechanical properties,workability,and cost-effectiveness while contributing to environmental sustainability.

Abstract:Objective Sodium oxalate is a representative recalcitrant organic pollutant.To enhance its degradation performance,a hierarchi-cally porous ceria-based copper catalyst is synthesized.The study investigated its catalytic ozonation mechanism,aiming to optimize ozone(O3)mass transfer efficiency thereby accelerating O3 decomposition into reactive oxygen species. Methods A ceria-based copper catalyst was synthesized via spray-drying technique and salt-templated synthesis method,using NaCl as a salt template and phenolic resin(PF)as a shaping agent.Various samples were obtained by varying the NaCl and PF addition amounts under identical processing conditions.The micro-morphologies of all samples were characterized through X-ray diffraction(XRD)patterns,scanning electron microscopy(SEM)images,pore size distribution curves,and X-ray photoelectron spectroscopy(XPS)spectra.The degradation performance of various ceria-based copper catalyst samples for sodium oxalate in an aqueous solution was investigated,and the sample with the optimal degradation performance was identified.Using 5,5-dimethyl-1-pyrroline N-oxide(DMPO)as a trapping agent for hydroxyl radicals,the primary reactive species in the solution were detected by electron spin resonance(ESR).The cycling stability of the optimal catalyst was studied through four repeated degradation experiments.Furthermore,the catalytic ozonation mechanism of the ceria-based copper catalysts was explored. Results and Discussion Micro-morphological characterization of various samples indicated that catalyst particle size significantly increased with higher NaCl mass,whereas PF addition exhibited minimal influence on particle size.However,PF dosage substantially affected pore structure and specific surface area.Without PF addition,the salt template and metal oxides within the particles were insufficiently encapsulated,resulting in structural collapse after washing.Conversely,excessive PF led to an overly thick coating layer that impeded pore formation.With a NaCl-to-PF mass ratio of 1∶1,the prepared sample Cu@CeO2-NaCl-PF exhibited an average particle size of approximately 35.3 nm,mesopore size of 5 nm-45 nm,and macro-pore size of 3 000 nm-5 000 nm.The specific surface area,mesopore volume,macropore volume,and total pore volume reached 52.15 m2/g,0.240 mL/g,4.778 mL/g,and 5.115 mL/g,respectively.The mass fractions of Cu0-Cu+and Ce3+were 67.1％and 18.7％,respectively.The sample Cu@CeO2-NaCl-PF demonstrated enhanced catalytic performance due to its larger specific surface area,multi-scale hierarchical porous structure,highly dispersed Cu active sites,and abundant low-valent metal ions.These structural advantages collectively promoted the gas-liquid-solid three-phase mass transfer,facilitating O3 enrichment on the catalyst surface while significantly accelerating the conversion rate.At a degradation time of 45 min,complete degradation(100％)of oxalate was achieved by sample Cu@CeO2-NaCl-PF.After the fourth cycle at a degradation time of 60 min,it main-tained 95％degradation efficiency,with the residual concentrations of copper ions(comprising Cu0-Cu+and Cu2+)in the solu-tion measured at 0.23 mg/L,0.27 mg/L,0.34 mg/L,and 0.37 mg/L sequentially across cycles,demonstrating exceptional recyclability at low leaching concentrations.Upon the addition of 1 mmol/L tert-butanol as a masking agent for hydroxyl radicals in the solution,the oxalate degradation rate of Cu@CeO2-NaCl-PF at 60 min was reduced to 10％,confirming hydroxyl radicals as the primary reactive oxygen species responsible for oxalate degradation.In contrast,when 1 mmol/L CCl4 was added as a masking agent for superoxide anions in the solution,its degradation rate exhibited only marginal reduction,indicating that super-oxide anions were not directly involved in oxalate degradation.The sample Cu@CeO2-NaCl-PF was demonstrated to accelerate O3 decomposition,generating hydroxyl radicals. Conclusion The catalyst Cu@CeO2-NaCl-PF is characterized by a relatively large specific surface area,a multi-scale hierarchi-cal porous structure,highly dispersed Cu active sites,and abundant low-valent metal ions.These features collectively enhance the gas-liquid-solid three-phase mass transfer and promote ozone enrichment on the catalyst surface,thus accelerating O3 conversion efficiency.The catalyst Cu@CeO2-NaCl-PF exhibits excellent cycling stability and remarkable capability in facilitat-ing O3 decomposition,generating hydroxyl radicals.

Abstract:Significance With the rapid development of global industrialization,energy scarcity and environmental pollution have become urgent problems.The pursuit of green and sustainable energy and technologies is key to solving these issues.Solar energy,as an ideal green energy source,holds immense potential for development.In 1911,the concept of"photocatalysis"first appeared when ZnO irradiation was found to bleach Prussian blue pigment.In 1972,the use of Pt as the counter electrode and TiO2 as an anode under UV irradiation effectively promoted water splitting for hydrogen production,marking a milestone in photocatalysisre-search.In recent years,to achieve carbon peaking and carbon neutrality goals while reducing greenhouse gas emissions,photoc-atalytic technology has been introduced into thermal catalysis processes to give full play to the synergistic effects of both processes,thereby improving overall catalyticperformance.Photothermal catalysis combines the high selectivity of photocatalysis with the thermal driving force.This synergistic approach improves the reaction rate and selectivity,offering an effective approach to address the high energy consumption and emission associated with traditional thermal catalysis and low efficiency of conventio-nal photocatalysis.As a rapidly emerging field,photothermal catalysis holds great potential for advancing green and sustainable development. Progress Photothermal catalysis mainly includes semiconductor catalysis and plasmonic metal catalysis.In semiconductor-based photothermal catalysis,a semiconductor serves as the main catalyst,with a metal co-catalyst facilitating electron transfer.When incident light energy exceeds the band gap of the semiconductor,electrons transition from the ground state to the excited state.Through effective separation and transfer,these electrons migrate to the co-catalyst,driving reduction or oxidation reactions.In plasmonic metal catalysis,when the incident light energy surpasses the natural frequency of electrons on the metal surface,hot electrons and local electric fields are generated.The reaction mechanism of photothermal catalysis is more complicated.It invol-ves photo-induced thermal effects,where photoreactions and thermoreactions share the same reaction mechanism,and photo-excited hot electron dynamics,where multiple oscillatory and relaxation effects of hot electrons influence reactant conversion.Also,hot electrons can be injected into the antibonding orbitals of adsorbed reactant molecules,which in turn promotes their act-ivation.Due to these complexities,the interplay between light and heat in photothermal catalytic systems remains to be explored.Kinetic analysis provides valuable insights into these mechanisms.By identifying adsorbed species on catalyst surfaces,confirm-ing rate determining step(RDS),and assessing the role of light,kinetic tools help elucidate reaction pathways.Pressure-depe-ndent experiments further reveal the reaction orders of reactants,intermediates,and products,offering insights into reaction progression and surface species abundance.Specifically,kinetic studies demonstrate that the introduction of light facilitates the transformation of major surface-adsorbed species.The contribution of light to catalytic activity can also be estimated through act-ivation energy measurements,and kinetic isotope effect(KIE)testing plays an important role in confirming RDS and reaction mechanisms. Conclusions and Prospects Under the background of carbon peaking and carbon neutrality,photothermal catalysis has demonst-rated increasingly significant research value in reducing energy consumption and addressing environmental pollution.It exhibits unique advantages in enhancing catalytic reaction performance.However,the reaction dynamics of photothermal catalysis are highly complex,and the interaction between light and thermal energy is not a simple superposition of their individual effects.The mechanism by which these two forms of energy influence reaction pathways remains unclear and requires further investigation.Despite these uncertainties,kinetic studies have provided valuable insights into the role of light in photothermal catalysis.By analyzing reaction orders,researchers have assessed the adsorption states of species on the catalyst surface.The contribution of light has been quantified through activation energy measurements,while RDS have been identified using KIE.The evolution of reactant molecules on the catalyst surface during photothermal reactions can be tracked kinetically,providing valuable insights into potential reaction pathways.This approach is crucial for understanding the mechanisms of photo-thermal catalysis and plays a crucial role in optimizing catalyst design for improved efficiency and stability.

Abstract:Objective To improve the performance of natural graphite raw materials and expand their application scope,a composite molten salt purification method is employed to purify the natural graphite raw materials,and the process parameters are optimized,aiming to improve production efficiency while reducing energy consumption and production costs. Methods The components of the natural graphite raw materials were analyzed.High-purity graphite was prepared at room temperature using a dilute hydrochloric acid leaching method,with NaOH,Na2CO3,Li2B4O7,Na2B4O7,and Li2CO3 serving as the molten salt components.The effects of inorganic salt types,composite molten salt formulations,calcination temperatures,and the mass of natural graphite raw materials on the purity of purified graphite were studied.Moreover,a comparative analysis of the microscopic morphologies of the natural graphite raw materials and the purified graphite was performed. Results and Discussion After two rounds of optimization experiments,NaOH,Na2CO3,and Na2B4O7 were selected as the formu-lation components of the composite molten salt.When the mass fraction of natural graphite raw material was 95.77％and the mass was set at 4 g,the respective masses of NaOH,Na2CO3,and Na2B4O7 were optimized to 1.0,0.5,and 1.0 g,with a calcination temperature of 700 ℃.Under these conditions,the mass fraction of purified graphite reached as high as 99.965％,with a mass ratio of NaOH to graphite of 1:5.5,and a composite molten salt to graphite mass ratio of 2.5:4.These parameters achieved an optimal balance between the equipment performance,production efficiency,and processing costs.The characteris-tic peaks in the X-ray diffraction(XRD)patterns of the purified graphite were highly consistent with the(002),(004),(100),and(110)crystal planes referenced in the graphite standard PDF card(PDF#41-1487),indicating that the composite molten salt method effectively removed impurities while preserving its crystalline structure.The purified graphite particles still maintained their ellipsoidal morphology,though with significantly diminished white substances on the particle surface and notably smoother surfaces,demonstrating the efficacy of the purification process in impurity elimination. Conclusion The composite molten salt method synergistically enhances the reaction with minerals by leveraging the advantages of individual salt components,effectively reducing alkali consumption while improving graphite purity.In terms of industrial production,this method simplifies the operational procedures,and its efficient alkali treatment process significantly reduces the difficulty of the subsequent acid treatment process.

Abstract:Significance In recent years,powder forming,a pivotal technique in near-net-shape manufacturing,has developed rapidly,impacting fields such as powder metallurgy,pharmaceuticals,and ceramic materials.This technique simplifies complex compo-nent processing,reduces material and energy consumption,and facilitates recycling of metallic wastes.In powder forming,the uniform distribution and loose density of powder during die filling are crucial to achieving a homogeneous microstructure in the final product.Any flaws such as the uneven distribution or inconsistencies in the powder cannot be corrected in later compres-sion steps.Thus,optimizing die filling processes and exploring their mechanisms have become a research focus to enhance prod-uct quality,reduce costs,advance material systems,accelerate green manufacturing,and broaden technological applications. Progress Given the diverse properties of powder materials and production requirements,die filling methods have become highly versatile.Selecting the appropriate die filling method(categorized as linear,suction,rotary,and forced feeding)is crucial for cost control,quality enhancement,and efficiency improvement.Each method offers unique strengths.Linear die filling is simple,cost-effective,and space-efficient.Suction die filling ensures superior uniformity and efficiency,especially for com-plex molds and powders of low-fluidity,minimizing the impact of material properties.Rotary die filling is well-suited for batch and continuous layered structures.Forced feeding die filling,with precise control,enhances powder fluidity and mixing.Mate-rial properties significantly influence uniformity and loose density in linear and rotary methods,while suction and forced feeding alleviate these constraints by improving powder fluidity.Additionally,environmental factors,including air,humidity,and static electricity,also exert complex effects on the filling process.However,the mechanisms underlying are yet to be fully explored,highlighting the need for rigorous environmental monitoring during operations. Conclusions and Prospects Linear die filling,as a traditional and widely used method,is well-suited for single-filling molding requirements of powder materials such as ceramics and cemented carbides,although its uniformity is constrained by multiple fac-tors,limiting its application in high-precision scenarios.Suction die filling,with optimized aspiration components,effectively reduces the interference of air resistance,thereby significantly enhancing filling efficiency,loose density,and uniformity.Although it allows for varying process parameters,further coordination and control among these parameters are still required to address the challenges posed by diverse powder material properties.Rotary die filling is effective in continuous operations,par-ticularly for small molds in medium-to-low-speed tablet presses,but its dependence on powder fluidity hinders its broader appli-cability.Forced feeding die filling,with optimized structure and paddle rotation,demonstrates immense potential in achieving high efficiency and uniformity,but at a higher cost.The following aspects need to be further studied:1)Leveraging forced feed-ing to enhance the uniformity of die filling,combining with suction mechanisms to improve filling density,and developing low-cost,high-precision,and widely applicable die filling processes.2)Introducing innovative applications of rotary and suction die filling methods into powder metallurgy,and developing a new suction-rotary die filling method to achieve uniform powder dis-tribution,high densification,and high efficiency.These approaches are instrumental in improving the process and equipment standards of China's powder metallurgy industry.3)Conducting a comprehensive and in-depth systematic investigation of key factors affecting die filling,especially the influences of environmental factors,such as air,humidity,and static electricity,as these factors vary with powder material characteristics.4)Based on the comprehensive analysis of die filling uniformity and den-sity,combined with the commonalities between die filling and powder laying processes,providing a more scientific reference and improvement strategies for the optimization of powder laying process in additive manufacturing.

Abstract:Objective To build electronic industrial cleanrooms that comply with the ISO Class 6 cleanliness standards while reducing energy consumption,this study focuses on optimizing non-unidirectional airflow ventilation schemes in electronic industrial cleanrooms. Methods For the non-unidirectional airflow organization in a cleanroom utilizing a make-up air unit-fan filter unit-dry cooling coil(MAU-FFU-DCC)ventilation system,computational fluid dynamics(CFD)simulations were conducted to evaluate four ventilation schemes.These schemes varied in air supply velocities and return air configurations,such as single-side or double-side returns,all operating under an upper-supply and side-return airflow pattern.A three-dimensional geometric model and a mathematical model of the cleanroom were established,and their reliability was verified.A systematic evaluation was conducted on the distribution characteristics of temperature and pressure fields of non-unidirectional airflow organization and the potential occurrence of upward airflow recirculation across different ventilation schemes.Three performance indices,temperature inhomo-geneity coefficient,thermal ventilation efficiency,and air age,were used to identify the optimal ventilation scheme that meets the ISO Class 6 cleanliness standards. Results and Discussion In the four ventilation schemes(S1,S2,S3,and S4),the average temperatures in the cleanroom were recorded as 22.04 ℃,21.95 ℃,21.98 ℃,and 21.80 ℃,respectively,all of which met the regulatory requirements for tem-perature.All four ventilation systems maintained a positive pressure environment.Compared to schemes S2 and S4 with an air supply velocity of 0.35 m/s,S,and S3with an air supply velocity of 0.30 m/s had lower air supply volumes and lower airflow pressure in the airflow patterns.Under the same supply velocities,no significant difference in pressure distribution was observed between the single-side return and double-side return configurations within the cleanroom.In single-side return schemes,eddies formed due to airflow collisions with walls on the non-outlet side,whereas in double-side return systems,the air was smoothly exhausted from both sides,reducing eddy phenomena.The average airflow deflection angles measured for S1,S2,S3,and S4 were 82.4°,83.5°,82.1°,and 83.2° respectively,all of which were below 90°.This indicated there was no upward return airflow in any of these schemes,thus meeting the cleanroom standards.The temperature non-uniformity coefficients for S1,S2,S3,and S4were calculated as 0.012,0.013,0.026,and 0.023,respectively,suggesting relatively uniform temperature distributions within the cleanroom.The thermal ventilation efficiency for these schemes reached 0.95,0.96,1.09,and 1.13,respectively.For the single-side return schemes,the efficiency was below 1,showing that the outlet temperatures were lower than those in the working zone.This resulted in insufficient heat exchange and energy waste.Conversely,in the double-side return schemes,the efficiency exceeded 1.0,with outlet temperatures higher than those in the working zone.This suggested more waste heat was absorbed before exhaust,leading to higher energy utilization efficiency and better economic viability.When the air supply velocities were 0.30 m/s and 0.35 m/s,the mean air ages for the single-side return schemes(S,and S2)were 75 s and 60 s,respectively,while those for the double-side return schemes(S3 and S4)were 60 s and 35 s,respectively.The mean air ages in S2,S3,and S4 met the regulatory standards and decreased with increasing air supply velocity.Notably,S3 required less air supply than S4,offering greater energy savings.Overall,the double-side return scheme with an air supply velocity of 0.3 m/s was found to be optimal.It delivered a cost-effective production environment that satisfied national cleanliness standards. Conclusion All four ventilation schemes demonstrate no upward airflow phenomena and meet the temperature and positive pres-sure requirements of the cleanroom.Among them,the double-side return scheme with an air supply velocity of 0.3 m/s is the most optimal one.It has a smaller air supply volume,conserves energy,and provides a cost-effective production environment that adheres to national cleanliness standards.

Abstract:Objective During the simulation design process of rod-pin sand mills,the study considers the distinct characteristics of gas and liquid phases by incorporating air phase dynamics into the simulation model to establish a gas-liquid-solid three-phase coupled simulation framework.This approach enables a more accurate representation of actual operating conditions,enhancing the accu-racy and reliability of numerical predictions. Methods A systematic methodology was developed for this simulation study.The discrete element method(DEM)and computa-tional fluid dynamics(CFD)were employed to model the solid and fluid phases,respectively.The volume of fluid(VOF)method was incorporated to distinguish between the liquid phase and gas phase within the fluid domain.By analyzing the govern-ing equations for solid-phase motion and fluid-phase dynamics,the gas-liquid interface tracking method and the coupled compu-tation framework were established,and a simulation workflow was developed.The accuracy of the CFD-DEM-VOF three-phase coupled model was evaluated through numerical simulations of single-particle water entry and particle swarm water entry.Rigor-ous verification procedures were implemented.Then,simulation parameters were configured,and computational meshes were generated,alongside grid independence analysis.The validated model was applied to simulate the operational conditions of a rod-pin sand mill.Finally,the simulated results,including slurry flow rate,total particle kinetic energy,and particle velocity distributions,were analyzed and compared with experimental data to validate the model's predictive capability. Results and Discussion In the single-particle water entry simulation,when the dynamic viscosity coefficients of water were 4×10-5,2×10-4,8×10-4,and 2×10-3 Pa·s(corresponding to Reynolds numbers of 107,11.34,1.09,and 0.20,respectively),the time required for particle velocity to stabilize was 0.054 6,0.047 6,0.032 2,and 0.028 0 s,respectively.The time required for the particle velocity to stabilize decreased as the dynamic viscosity coefficient of water increased.The simulation results from the CFD-DEM-VOF three-phase coupling model showed good agreement with the theoretical calculations based on Stokes' law.In the particle swarm water entry simulation,the relative error between the simulated and theoretical values of the liquid surface rise heights was 1.37％,demonstrating the volume conservation capability of the CFD-DEM-VOF three-phase coupling model.The tangential velocity of tetrahedral mesh first increased and then decreased with radial distance,reaching its maximum at a radial distance of 8 mm.When the edge length of the tetrahedral mesh for the rod-pin was less than 2 mm and that for the grinding barrel was less than 2.5 mm,the relative error of tangential velocity of the tetrahedral mesh was 3.23％,meet-ing the accuracy requirements for grid independence while maintaining a reasonable computational load.As the rod-pin rota-tional speed increased,the fluid velocity,total particle kinetic energy,and average particle velocity also increased.For each rotational speed,the CFD-DEM-VOF three-phase coupled model exhibited closer agreement between the simulated and experi-mental values for fluid velocity,total particle kinetic energy,and average particle velocity compared to single-fluid-phase,single-solid-phase,or solid-liquid two-phase models.At rotational speeds ranging from 1 400 r/min to 2 200 r/min,the relative error between the simulated and experimental values for fluid velocity in the CFD-DEM-VOF three-phase coupled model was minimized to 0.25％,representing the closest agreement between simulation and experimental results.At rotational speeds rang-ing from 1 400 r/min to 2 200 r/min,the maximum relative error for total particle kinetic energy was 1％,further validating the model's predictive capability. Conclusion Compared to using single-fluid or solid-phase models or solid-liquid two-phase models,the CFD-DEM-VOF three-phase coupled model demonstrates significantly enhanced computational accuracy and precision in designing rod-pin sand mills,with superior simulation performance.

Abstract:Objective To investigate the effects of phosphoric acid(H3PO4)-modified triethanolamine(TEA)on the mechanical properties and impermeability of cement mortar,with the aim of addressing the performance limitations of conventional TEA in cement-based systems. Methods H3PO4 was used as a modifying agent and modified TEA was synthesized by reacting H3PO4 with TEA at molar ratios of 0.8,1.0,and 1.2.The mechanical properties and impermeability of cement mortar were evaluated by measuring compres-sive strength,drying shrinkage,and chloride ion permeability after incorporating the modified TEA.The effects of modified TEA on the hydration products and microstructure of the cement matrix were analyzed using X-ray diffraction(XRD)and scan-ning electron microscopy(SEM).A semi-quantitative analysis of hydration product content was performed using Jade9 soft-ware,and mercury intrusion porosimetry(MIP)was employed to examine changes in pore structure. Results and Discussion Compared to the control group,all types of modified TEA improved the 3-day and 28-day flexural and compressive strengths of the cement mortar.The strengths exhibited a trend of first increasing and then decreasing with increas-ing dosage.For flexural strength,the optimal dosage was identified as 0.02％for all modifiers.At this dosage,the modifier syn-thesized at an H3PO4:TEA molar ratio of 1 exhibited the greatest improvement(15.7％increase at 3 days,7.5％at 28 days),followed by the modifier at a ratio of 0.8(11.0％at 3 days and 4.6％at 28 days),and then the modifier at a ratio of 1.2(9.2％at 3 days and 5.4％at 28 days).For compressive strength,the optimal dosage shifted to 0.04％.The modifier synthesized at an H3PO4:TEA molar ratio of 0.8 showed the most significant enhancement(21.4％increase at 3 days and 13.4％at 28 days),fol-lowed by the ratio 1 modifier(16.9％at 3 days and 8.5％at 28 days),and then the ratio 1.2 modifier(15.0％at 3 days and 7.4％at 28 days).Notably,the modifier with an H3PO4:TEA molar ratio of 0.8 achieved the highest strength values at its opti-mal dosage,effectively mitigating the long-term strength decline typically observed with unmodified TEA.All modified TEA sig-nificantly reduced chloride ion permeability.The modifier synthesized at an H3PO4:TEA molar ratio of 0.8 again showed the most pronounced effect.For this modifier,the chloride ion permeability first decreased and then increased with increasing dos-age,reaching its minimum value(25.3％reduction compared to the control)at a dosage of 0.04％.The modifiers at molar ratios of 1 and 1.2 also reduced permeability by 17.9％and 15.6％,respectively,at the same dosage.When the dosage exceeded 0.06％,the permeability of the modifiers at ratios 1 and 1.2 continued to decrease gradually.Compared to the con-trol,the incorporation of modified TEA reduced drying shrinkage at various ages,though shrinkage still increased over time.The modifier synthesized at an H3PO4:TEA molar ratio of 0.8 resulted in the lowest shrinkage,with a 12.1％reduction at a dos-age of 0.04％.The modifiers at molar ratios of 1 and 1.2 reduced shrinkage by 10.6％and 3.2％,respectively,at the same 0.04％dosage.This reduction in shrinkage was associated with a decrease in capillary porosity.XRD analysis confirmed that modified TEA did not produce new hydration products.However,semi-quantitative analysis of 28 days samples revealed that the modifier synthesized at an H3PO4:TEA molar ratio of 0.8 increased the contents of hydration products(monosulfate,ettring-ite,and calcium hydroxide)and reduced the contents of unhydrated clinker minerals compared to the control.Early-age(3 days)XRD patterns showed higher peak intensities of AFt and Ca(OH)2 in samples containing the 0.8-ratio modifier,indicat-ing accelerated hydration of both C3A and C3S.SEM micrographs illustrated microstructural refinement induced by the modifier synthesized with ratio of 0.8.At 3 days,the sample exhibited a denser structure with interwoven C-S-H gel,AFt,and embed-ded Ca(OH)2 crystals filling the pores,in contrast to the relatively loose and porous structure of the control.At 28 days,the sample displayed a tightly packed microstructure with minimal visible pores,in stark contrast to that of the control group.MIP analysis showed that the modifier synthesized at an H3PO4:TEA molar ratio of 0.8 significantly improved the pore structure at 0.04％dosage,total porosity was reduced by 15.9％,and average pore diameter was reduced by 21.5％.Crucially,the propor-tions of harmful pores(50～200 nm)and larger harmful pores(＞200 nm)decreased,while the proportions of less harmful pores(20～50 nm)and harmless pores(＜20 nm)increased.Similar improvements,though less pronounced,were also observed for modifiers synthesized at molar ratios of 1 and 1.2.This refinement in pore structure directly contributed to the enhancements in strength and impermeability. Conclusion The addition of H3PO4-modified TEA enhances the degree of cement hydration,promotes the growth of hydration products,regulates the morphology of hydration products,improves structural density,optimizes the pore structure,and ulti-mately increases the strength and impermeability of the cement mortar.

Abstract:Significance This paper explores the application and development of chemical agent-assisted vacuum preloading in sludge dewatering treatment.It aims to optimize chemical agent selection and dosage to enhance sludge dewatering efficiency,improve soil consolidation,and reduce treatment costs. Progress Sludge composition and microstructure are comprehensively reviewed in the study.Sludge is a complex mixture of organic pollutants,viruses,inorganic minerals,microplastics,and heavy metals,and it is characterized by a stable flocculent structure.Based on the mechanical properties of sludge from landfills in Shanghai and Shenzhen,the variation patterns of sludge parameters were analyzed,including organic matter content,particle size distribution,water content,permeability coefficient,compressibility,and strength.The organic matter content ranges from 20.1％to 52.2％,with an average value of 45％.The water content varies from 190％to 630％,with an average of 500％.The permeability coefficient is within the range of 0.52×10-8 to 1.7×10-8 cm/s.These data demonstrate that sludge is characterized by high water content and poor permeability.The water in sludge exists in the states of free water,capillary water,and bound water.Common dewatering methods include centrifugal dewatering,filter-press dewatering,electrokinetic dewatering,and thermal dewatering,with the dewatering efficiency increas-ing from the former to the latter.Vacuum preloading,adapted from silt foundation reinforcement,was initially studied in 1957 by Chinese researchers and has been widely adopted since 1995.During the drainage process when using this method,soil par-ticles migrate directionally and uniformly towards the drainage board.Clay particles accumulate around the drainage board,forming a clogging layer that impairs drainage.To address these limitations,chemical agents are introduced to sludge treatment.To promote particle aggregation and enlarge sludge particle size,inorganic and organic flocculants are commonly employed.Oxi-dants such as Fenton's reagent are utilized to break down extracellular polymeric substances(EPS)and release bound water,thereby enhancing drainage volume.Alkaline materials are used to facilitate chemical modification and promote particle agglom-eration.The aggregation of particles can effectively reduce directional migration towards the drain and improve the localized arrangement of particles near the drainage board,thus relieving the clogging problem of vacuum preloading. Conclusions and Prospects Flocculants are broadly categorized into inorganic and organic types,each with distinct advantages and limitations.Inorganic flocculants,though relatively cost-effective,require higher dosages and may pose greater environmen-tal risks.Specifically,metal-based flocculants may cause secondary heavy metal pollution.In contrast,organic flocculants achieve superior performance with smaller dosages.Current research primarily focuses on the combined application of inorganic and organic flocculants to leverage the strengths of both.The aggregation of particles by flocculants and the release of free water from sludge by oxidants enhance the permeability of sludge and increase the total drainage volume.Compared to conventional vacuum preloading,chemical agent-assisted vacuum preloading demonstrates marked advantages,including shorter construc-tion periods,lower energy consumption,and improved dewatering effect,as evidenced by key indicators like water content,shear strength,and settlement efficiency.The optimal dosages of chemical agents vary depending on sludge types and the initial water content.In practical projects,the selection and dosage of agents should be optimized based on the specific characteristics of the sludge.At present,chemical agents still pose environmental risks.Future efforts should focus on integrating various types of chemicals to develop efficient,green,and eco-friendly agents.Additionally,it is essential to explore intelligent sludge treat-ment technologies and equipment to further advance the development and application of chemical agent-assisted vacuum preload-ing in sludge dewatering.

Abstract:Objective The study aims to investigate the heat and mass transfer characteristics of fluidized bed drying under pulsating airflow and to regulate the drying process of non-spherical wet particles. Methods Numerical simulations were conducted to study the fluidized bed drying process of non-spherical wet particles.The computational fluid dynamics-discrete element method(CFD-DEM)was employed to characterize the gas-particle flow and mass/heat transfer behaviors.To achieve an accurate characterization of non-spherical wet particles,a flow-heat/mass transfer model was developed considering the variations in inter-particle liquid bridge forces.In this model,the equivalent radius at the contact position was used in place of the particle radius when calculating liquid bridge forces.Liquid migration during particle collisions was also incorporated,along with the influence of liquid bridges on heat transfer and variations in gas-phase water vapor concentration during drying.The evolution of heat and mass transfer for non-spherical wet particles in a spouted bed dryer was studied,and the influence of sinusoidal and rectangular wave-shaped pulsating airflows on fluidized bed drying behavior was analyzed. Results and Discussion The proposed model was validated against experimental data.The results showed that,as drying pro-gressed,the liquid content of particles gradually decreased and particle agglomeration weakened.Compared to non-pulsating airflow,pulsating airflow significantly increased the drying rate,resulting in a smaller drying dead zone.Under rectangular wave-shaped pulsating airflow,particles in the annular region were difficult to fluidize,leading to a larger dead zone compared to sinusoidal waveform.The total pressure drop under the rectangular wave-shaped pulsating airflow was lower than that under sinusoidal wave-shaped pulsating airflow.As drying continued,more particles participated in fluidization under sinusoidal wave-shaped pulsating airflow,whereas the rectangular wave-shaped pulsating airflow showed no significant improvement in flu-idization.Compared to sinusoidal wave-shaped pulsating airflow,rectangular wave-shaped pulsating airflow exhibited a slower particle heating rate,and in the later stage of drying,a larger standard deviation of particle temperature in the bed indicated rela-tively weaker and more heterogeneous heat transfer between gas and particles.In contrast,sinusoidal wave-shaped pulsating air-flow demonstrated higher heat transfer efficiency,with a more uniform temporal and spatial distribution of gas-particle heat trans-fer.Rectangular wave-shaped pulsation exhibited lower heat transfer via liquid bridges and wet particle contact.Notably,dry particle contact conduction emerged earlier in the spouted bed under rectangular wave-shaped pulsating airflow,indicating pre-mature complete drying of some non-spherical wet particles.The drying rate and its standard deviation evolved differently over time under pulsating airflows of different waveforms.Specifically,the drying rate under rectangular wave-shaped pulsating air-flow declined earlier due to insufficient gas-particle contact for certain particles in the later drying stage,which reduced the over-all drying rate in the bed. Conclusion The introduction of pulsating airflow improves flow behavior in the spouted bed dryer to a certain extent,reduces fluidization dead zones in the annular region,accelerates the drying process,and improves the drying uniformity.During par-ticle heat transfer,wet particle contact heat conduction plays a dominant role.As drying progresses,the volume of liquid bridges decreases continuously,thereby weakening heat conduction.Compared to sinusoidal wave-shaped pulsating airflow,rectangular wave-shaped pulsed airflow causes some particles to dry completely at an earlier stage.In contrast,sinusoidal wave-shaped pulsating airflow more effectively enhances the fluidized drying of non-spherical wet particles,improving both heat and mass transfer efficiency and overall drying uniformity.

Abstract:Significance The rising concentrations of greenhouse gases have intensified global warming,posing a significant challenge to human society.Carbon sequestration and utilization within the building materials sector are crucial for achieving China's dual carbon goals.CO2 mineralization and sequestration are vital components of carbon emission reduction technologies,with CO2foam concrete(CFC)demonstrating substantial potential for large-scale CO2 sequestration.With the implementation of national energy conservation and emission reduction policies,CFC,as an energy-efficient and environmentally friendly mate-rial,offers advantages such as lightweight properties,fire resistance,and thermal insulation.Consequently,it is poised to play a significant role in construction,municipal infrastructure,tunnels,bridges,and related fields.Furthermore,the comprehen-sive utilization of coal-based solid waste and power plant flue gas CO2 is essential for coal-based power enterprises to achieve green,low-carbon,and circular development.This approach facilitates the resource utilization of coal-based solid waste,CO2 mineralization and storage from power plants,mine water recycling,and underground filling for disaster management. Progress 1)Ordinary Portland cement is rarely used in CFC production.Instead,solid waste serves as a partial replacement for cementitious materials,representing a key development direction.The combination of CO2-soluble surfactants and nanoparticles is the preferred approach for CFC blowing agents.Currently,pre-foaming is the most widely employed preparation process for CFC.2)CO2 mineralization is a primary factor influencing the stability of CFC foam.The mineralization process encompasses the stages of mixing CO2 with concrete,foaming,and concrete hardening.The growth mechanism of CO2 bubbles is complex and warrants investigation using simulation,visualization,and other technical methods.3)Within the CFC system,CO2 preferen-tially reacts with the hydration product Ca(OH)2.The resultant products adhere to the surfaces of both Ca(OH)2 and C3S,lead-ing to a gradual weakening of carbonization and hydration.Simultaneously,C2S participates in the carbonation reaction,with mineralization directly causing a significant number of CO2 foam ruptures,thereby diminishing the foaming effect.4)The car-bon sequestration potential of CFC is substantial,primarily manifested in the carbonation and carbon sequestration of the con-crete skeleton,as well as the carbon storage within bubble pores.Among these factors,the carbonation and carbon sequestra-tion of the concrete skeleton play a predominant role.Utilizing solid waste materials,such as waste concrete powder,fly ash,and slag,as substitutes for cementitious materials is crucial to reducing the environmental impact of CFC production.Further-more,industrial waste gases from power generation and metallurgy should serve as the primary sources of CO2. Conclusions and Prospects The future development directions of CFC are outlined as follows:1)The incorporation of industrial solid waste into CFC production represents a significant strategy for enhancing its economic viability.CFC demonstrates poten-tial for large-scale CO2 storage.However,energy consumption and economic efficiency remain unresolved issues.Fly ash,slag,coal gangue,and steel slag are commonly used as admixtures in CFC formulations.These materials not only enhance the performance of foam concrete but also address solid waste management challenges.Additionally,they improve the economic value of CFC while facilitating its widespread adoption.2)CO2 derived from industrial processes such as power generation and metallurgy should be considered as primary foaming gas sources for CFC.Currently,CO2is obtained through high-value chemi-cal reagents or compressed gas,resulting in elevated economic costs that hinder the promotion and application of CFC technol-ogy.In contrast,thermal power plants and metallurgical industries generate abundant CO2 emissions,often treating these emis-sions as pollutants.Consequently,integrating CFC production into such industrial sites offers both economic and environmental advantages.3)Research on CFC should prioritize improving its carbon sequestration capacity and foam stability.The current mineralization rate of CO2in concrete is relatively low due to limitations in CO2 diffusion,which primarily occurs within the sur-face and shallow layers of concrete.Implementing three-dimensional curing methods can address this issue by promoting deeper CO2 penetration and enhancing foam retention.Further studies should focus on understanding CFC's cellular structure,carbon sequestration mechanisms,and modification techniques at a microscopic level to optimize its performance.