In view of the volume instability of steel slag aggregate leading to the quality problem of expansion damage in asphalt road construction,the 4.75-9.5 mm steel slag particles were treated by autoclaved carbonation tec...In view of the volume instability of steel slag aggregate leading to the quality problem of expansion damage in asphalt road construction,the 4.75-9.5 mm steel slag particles were treated by autoclaved carbonation technology,and the effects of the carbonation system(temperature and time)on the autoclaved pulverization rate,f-CaO content,and the relationship between them for the carbonated steel slag were investigated.In addition,the microstructure of the carbonated steel slag was analyzed by X-ray diffractometer(XRD),scanning electron microscope and energy dispersive spectrometer(SEM-EDS),metallographic microscope and X-ray fluorescence imaging spectrometer(XRF).The experimental results indicate that,under the initial CO_(2)pressure of 1.0 MPa,increasing the carbonation temperature leads to the increase in the crystal plane spacing of Ca(OH)_(2)that was generated by the hydration of minerals in steel slag,and promotes the transformation of carbonated CaCO_(3)from the orthorhombic system to the hexagonal system,resulting in the increase of the crystal planes spacing of them,meantime,accelerates the decomposition of RO phases and also the outward migration of Ca^(2+),Fe^(2+),and Mn^(2+)ions to cover and coat on the Si^(4+),Al^(3+)ions,and impels the formation of hydroxides such as Fe(OH)_(3)and the formation of carbonates such as Ca(Mg)CO_(3),FeCO_(3)and MnCO_(3).Carbonation at the temperature of 90℃for 3 h can reach the center of 4.75-9.5 mm steel slag particles.Meanwhile,the increase of temperature can promote the mineral reaction in steel slag,resulting in the fuzzy interface between mineral phases,increase of burrs,dispersion,crossover,reduction of grain size,and rearrangement of mineral particles.展开更多
Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed.The surface properties and structure of birnessite change with the changes in external environmental condition...Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed.The surface properties and structure of birnessite change with the changes in external environmental conditions,which also affects the fate of heavy metals.Clarifying the effect and mechanism of the birnessite phase transition process on heavy metals is the key to taking effective measures to prevent and control heavy metal pollution.Therefore,the four transformation pathways of birnessite are summarized first in this review.Second,the relationship between transformation pathways and environmental conditions is proposed.These relevant environmental conditions include abiotic(e.g.,co-existing ions,pH,oxygen pressure,temperature,electric field,light,aging,pressure)and biotic factors(e.g.,microorganisms,biomolecules).The phase transformation is achieved by the key intermediate of Mn(Ⅲ)through interlayer-condensation,folding,neutralizationdisproportionation,and dissolution-recrystallization mechanisms.The AOS(average oxidation state)of Mn and interlayer spacing are closely correlated with the phase transformation of birnessite.Last but not least,the mechanisms of heavy metals immobilization in the transformation process of birnessite are summed up.They involve isomorphous substitution,redox,complexation,hydration/dehydration,etc.The transformation of birnessite and its implication on heavy metals will be helpful for understanding and predicting the behavior of heavy metals and the crucial phase of manganese oxides/hydroxides in natural and engineered environments.展开更多
The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has...The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has been employed as a coating agent.The SEM micrographs revealed distinct features of both pure AN and NC,contrasting with the irregular granular surface topography of the coated AN particles,demonstrating the adherence of NC on the AN surface.Structural analysis via infrared spectroscopy(IR)demonstrated a successful association of AN and NC,with slight shifts observed in IR bands indicating interfacial interactions.Powder X-ray Diffraction(PXRD)analysis further elucidated the structural changes induced by the coating process,revealing that the NC coating altered the crystallization pattern of its pure form.Thermal analysis demonstrates distinct profiles for pure and coated AN,for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6℃,and 36%,respectively.Furthermore,the presence of NC coating alters the intermolecular forces within the composite system,leading to a reduction in melting enthalpy of coated AN by~39%compared to pure AN.The thermal decomposition analysis shows a two-step thermolysis process for coated AN,with a significant increase in the released heat by about 78%accompanied by an increase in the activation barrier of NC and AN thermolysis,demonstrating a stabilized reactivity of the AN-NC particles.These findings highlight the synergistic effect of NC coating on AN particles,which contributed to a structural and reactive stabilization of both AN and NC,proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.展开更多
Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of time.However,before...Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of time.However,before the formation of stable rust layers,weathering steel is prone to liquid rust sagging and spattering,leading to environmental pollution and city appearance concerns.These factors limit the application and development of weathering steel.In this study,a rapid and environmentally friendly method was de-veloped by introducing alloying elements,specifically investigating the role of Sn in the rapid stabilization of rust layers in marine atmo-spheric environments.The rust layer formed on weathering low-alloy steel exposed to prolonged outdoor conditions and laboratory im-mersion experiments was explored using electron probe micro-analyzer(EPMA),micro-Raman,X-ray photoelectron spectroscopy(XPS),and electrochemical measurements.Results showed an optimal synergistic effect between Sn and Cr,which facilitated the accelerated densification of the rust layer.This beneficial effect enhanced the capability of the rust layer to resist Cl^(-)erosion and improved the protec-tion performance of the rust layer.展开更多
Although perovskite solar cells(PSCs) demonstrate outstanding power conversion efficiency(PCE), their practical applications are still limited by stability issues caused by various problems such as poor crystal qualit...Although perovskite solar cells(PSCs) demonstrate outstanding power conversion efficiency(PCE), their practical applications are still limited by stability issues caused by various problems such as poor crystal quality triggered structural instability. Herein, to address the structural instability of perovskites, we introduced a polymer additive, poly-L-lysine hydrobromide(PLL), into the perovskite precursor to promote perovskite crystal growth, thereby constructing a stable crystal structure. The results show that the introduction of PLL modulates the colloidal aggregation state in the precursor solution, provides longer time for growth of perovskite and successfully realizes the formation of large-sized perovskite films with high crystallinity. More importantly, owing to its hydrophobic long-chain structure and the widespread distribution of C=O and NH on the chain, PLL firmly locks the perovskite crystals, enhancing their structural stability while blocking the intrusion of external factors such as water molecules, significantly enhances the overall stability of the device. The results show that the PLL-based PSC has negligible hysteresis and its PCE is improved from 22.20% to 23.66%. while the PLL-modified perovskite films and devices demonstrate excellent thermal and environmental stability. These findings highlight PLL as a promising additive for optimizing perovskite crystallization, offering guidance for fabricating efficient and stable photovoltaic devices.展开更多
In the context of the digital transformation of vocational education,a quality evaluation index system has been constructed.Based on a questionnaire survey conducted among higher vocational colleges and enterprises in...In the context of the digital transformation of vocational education,a quality evaluation index system has been constructed.Based on a questionnaire survey conducted among higher vocational colleges and enterprises in Hainan Province,it has been found that the quality of vocational education generally depends on the talent training program and professional construction at the macro level.At the meso level,the teacher level and teaching environment are critical,while at the micro level,the evaluation of talent training quality cannot be underestimated.Strategies for quality improvement in vocational education are proposed from the perspectives of talent training programs,major construction,teacher development,teaching environment,and talent training quality,all under the lens of digital transformation.展开更多
Agrobacterium tumefaciens-mediated transformation has been widely adopted for plant genetic engineering and the study of gene function(Krenek et al.,2015).This method is prevalent in the genetic transformation of herb...Agrobacterium tumefaciens-mediated transformation has been widely adopted for plant genetic engineering and the study of gene function(Krenek et al.,2015).This method is prevalent in the genetic transformation of herbaceous plants,with notable applications in species such as Arabidopsis(Yin et al.,2024),soybean(Zhang et al.,2024),rice(Zhang et al.,2020),and Chinese cabbage(Li et al.,2021).However,its application in fruit trees is limited.This is primarily due to their long growth cycles and lack of rapid,efficient,and stable transgenic systems,which severely hinders foundational research involving plant genetic transformation(Mei et al.,2024).Furthermore,for subtropical fruit trees,the presence of recalcitrant seeds adds an extra layer of difficulty to genetic transformation(Umarani et al.,2015),as most methods rely on seed germination as a basis for transformation.展开更多
Theβsolidifiedγ-TiAl alloy holds important application value in the aerospace industry,while its com-plex phase compositions and geometric structures pose challenges to its microstructure control during the thermal-...Theβsolidifiedγ-TiAl alloy holds important application value in the aerospace industry,while its com-plex phase compositions and geometric structures pose challenges to its microstructure control during the thermal-mechanical process.The microstructure evolution of Ti-43Al-4Nb-1Mo-0.2B alloy at 1200℃/0.01 s−1 was investigated to clarify the coupling role of dynamic recrystallization(DRX)and phase transformation.The results revealed that the rate of DRX inα2+γlamellar colonies was comparatively slower than that inβo+γmixed structure,instead being accompanied by intense lamellar kinking and rotation.The initiation and development rates of DRX inα2,βo,andγphases decreased sequentially.The asynchronous DRX of the various geometric structures and phase compositions resulted in the un-even deformed microstructure,and the dynamic softening induced by lamellar kinking and rotation was replaced by strengthened DRX as strain increased.Additionally,the blockyα2 phase and the terminals ofα2 lamellae were the preferential DRX sites owing to the abundant activated slip systems.Theα2→βo transformation within lamellar colonies facilitated DRX and fragment ofα2 lamellae,while theα2→γtransformation promoted the decomposition ofα2 lamellae and DRX ofγlamellae.Moreover,the var-iedβo+γmixed structures underwent complicated evolution:(1)Theγ→βo transformation occurred at boundaries of lamellar colonies,followed by simultaneous DRX ofγlamellar terminals and neighboringβo phase;(2)DRX occurred earlier within the band-likeβo phase,with the delayed DRX in enclosedγphase;(3)DRX within theβo synapses and neighboringγphase was accelerated owing to generation of elastic stress field;(4)Dispersedβo particles triggered particle stimulated nucleation(PSN)ofγphase.Eventually,atomic diffusion along crystal defects inβo andγphases caused fracture of band-likeβo phase and formation of massiveβo particles,impeding grain boundary migration and hindering DRXed grain growth ofγphase.展开更多
Objectives:Cold-acclimated organisms accumulate low molecular weight organic solutes such as sugar alcohols and soluble sugars.This study aimed to compare the efficacy of five sugar alcohols and 14 soluble sugars in s...Objectives:Cold-acclimated organisms accumulate low molecular weight organic solutes such as sugar alcohols and soluble sugars.This study aimed to compare the efficacy of five sugar alcohols and 14 soluble sugars in stabilizing proteins under freezing,freeze-drying,and air-drying stresses.Materials and methods:Glucose-6-Phosphate Dehydrogenase(G6PD)was used as the model protein.G6PD solutions with or without sugar alcohols and or sugars were subjected to freezing,freeze-drying,and air-drying stresses.The recovery of G6PD activity was measured to evaluate the protective efficacy of these compounds.Results:Without stabilizers,freezing G6PD at-20℃ or-80℃ reduced enzyme activity by around 24%,while freeze-drying or air-drying reduced activity by 90%-95%.Among the five sugar alcohols tested,pinitol,quebrachitol and sorbitol stabilized G6PD,whereas mannitol and myo-inositol destabilized it.Among 14 soluble sugars,trehalose and raffinose showed slightly lower enzyme recovery after repeated freeze-thaw cycles at-20℃.Most soluble sugars(except arabinose and xylose)protected G6PD during freeze-drying,with di-,tri-,and oligosaccharides generally outperforming monosaccharides.During air-drying,lactose was ineffective,while arabinose,galactose,and xylose were detrimental.Conclusion:The study highlights the diverse mechanisms of sugar alcohols and sugars in protein stabilization under stress,offering insights for formulating stable protein-and cell-based drugs.展开更多
The transformation from multibody models to lumped-parameter models is a crucial aspect of vehicle dynamics research.The velocity transformation method is adopted in this research,and the suspension multibody model is...The transformation from multibody models to lumped-parameter models is a crucial aspect of vehicle dynamics research.The velocity transformation method is adopted in this research,and the suspension multibody model is described using only one degree of freedom.It is found that the equivalent mass of the system is time-dependent during the simulation process,as observed in numerical simulations.Further symbolic calculations are conducted to derive the analytical form of the equivalent mass,and the results show that once the static parameters are determined,the equivalent mass of the suspension system is determined solely by the vertical position of the suspension upright,which reveals the kinematics characteristic of the equivalent mass of the suspension system.It is found that the equivalent mass experiences smaller changes when the suspension is compressed from the middle position,but larger changes when the suspension is extended.Furthermore,by comparing the multibody model,the lumped-parameter model with static mass,and the proposed lumped-parameter model considering the kinematics characteristic of the equivalent unsprung mass,the proposed model produces simulation results that more closely match the original multibody model than the model with static mass.The improvements in accuracy can be up to 20%under certain evaluation metrics.展开更多
This study investigates the innovative reuse of sewage sludge with eco-friendly alkaline solutes to improve clayey soil without conventional cementitious binders.The unconfined compressive strength(UCS)was the main cr...This study investigates the innovative reuse of sewage sludge with eco-friendly alkaline solutes to improve clayey soil without conventional cementitious binders.The unconfined compressive strength(UCS)was the main criterion to assess the quality and effectiveness of the proposed solutions,as this test was performed to measure the strength of the stabilized clay by varying binders’dosages and curing times.Moreover,the direct shear test(DST)was used to investigate the Mohr-Coulomb parameters of the treated soil.Microstructure observations of the natural and treated soil were conducted using scanning electron microscope(SEM),energy-dispersive spectroscopy(EDS),and FTIR.Furthermore,toxicity characteristic leaching procedure(TCLP)tests were performed on the treated soil to investigate the leachability of metals.According to the results,using 2.5%of sewage sludge activated by NaOH and Na_(2)SiO_(3)increases the UCS values from 176 kPa to 1.46 MPa after 7 d and 56 d of curing,respectively.The results of the DST indicate that sewage sludge as a precursor increases cohesion and enhances frictional resistance,thereby improving the Mohr-Coulomb parameters of the stabilized soil.The SEM micrographs show that alkali-activated sewage sludge increases the integrity and reduces the cavity volumes in the stabilized soil.Moreover,TCLP tests revealed that the solubility of metals in the treated soil alkaliactivated by sewage sludge significantly decreased.This study suggests that using sewage sludge can replace cement and lime in ground improvement,improve the circular economy,and reduce the carbon footprint of construction projects.展开更多
This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that ...This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.展开更多
The effects of plasma screening on the ^(1)P^(o) resonance states of H-and He below the n=3 and n=4 thresholds of the respective subsystemsare investigated using the stabilization method and correlated exponential wav...The effects of plasma screening on the ^(1)P^(o) resonance states of H-and He below the n=3 and n=4 thresholds of the respective subsystemsare investigated using the stabilization method and correlated exponential wave functions.Two plasma mediums,namely,the Debye plasma and quantum plasma environments are considered.The screened Coulomb potential(SCP)obtained from Debye-Hückel model is used to represent Debye plasma environments and the exponential cosine screened Coulomb potential(ECSCP)obtained from a modified Debye-Hückel model is used to represent quantum plasma environments.The resonance parameters(resonance positions and widths)are presented in terms of the screening parameters.展开更多
In this paper we use Böcklund transformation to construct soliton solutions for a coupled KdV system.This system was first proposed by Wang in 2010.First we generalize the well-known Bäcklund transformation ...In this paper we use Böcklund transformation to construct soliton solutions for a coupled KdV system.This system was first proposed by Wang in 2010.First we generalize the well-known Bäcklund transformation for the KdV equation to such coupled KdV system.Then from a trivial seed solution,we construct soliton solutions.We also give a nonlinear superposition formula,which allows us to generate multi-soliton solutions.展开更多
Hydrogen-based mineral phase transformation(HMPT)technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores.However,further research is needed to clarify ...Hydrogen-based mineral phase transformation(HMPT)technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores.However,further research is needed to clarify the phase composition and floatability of rare earths obtained after HMPT owing to the associated phase transformations.This study explored the mineralogical characteristics and separation behavior of rare earths in HMPT-treated iron tailings.Process mineralogy studies conducted via BGRIMM process mineralogy analysis and X-ray diffraction revealed that the main valuable minerals in the tailings included rare-earth oxides(9.15wt%),monazite(5.31wt%),and fluorite(23.52wt%).The study also examined the impact of mineral liberation and gangue mineral intergrowth on flotation performance.Flotation tests achieved a rare-earth oxide(REO)grade of 74.12wt% with a recovery of 34.17% in open-circuit flotation,whereas closed-circuit flotation resulted in a REO grade of 60.27wt% with a recovery of 73%.Transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy revealed that monazite remained stable during the HMPT process,while bastnaesite was transformed into Ce_(7)O_(12)and CeF_(3),leading to increased collector consumption.Nonetheless,the HMPT process did not significantly affect the flotation performance of rare earths.The enrichment of fluorite in the tailings highlighted its further recovery potential.The integration of HMPT with magnetic separation and flotation presents an efficient strategy for recovering rare earths,iron,and fluorite from Bayan Obo ores.展开更多
With the continuous expansion and increasing complexity of power system scales,the binary classifica-tion for transient stability assessment in power systems can no longer meet the safety requirements of power system ...With the continuous expansion and increasing complexity of power system scales,the binary classifica-tion for transient stability assessment in power systems can no longer meet the safety requirements of power system control and regulation.Therefore,this paper proposes a multi-class transient stability assessment model based on an improved Transformer.The model is designed with a dual-tower encoder structure:one encoder focuses on the time dependency of data,while the other focuses on the dynamic correlations between variables.Feature extraction is conducted from both time and variable perspectives to ensure the completeness of the feature extraction process,thereby enhancing the accuracy of multi-class evaluation in power systems.Additionally,this paper introduces a hybrid sampling strategy based on sample boundaries,which addresses the issue of sample imbalance by increasing the number of boundary samples in the minority class and reducing the number of non-boundary samples in the majority class.Considering the frequent changes in power grid topology or operation modes,this paper proposes a two-stage updating scheme based on self-supervised learning:In the first stage,self-supervised learning is employed to mine the structural information from unlabeled data in the target domain,enhancing the model’s generalization capability in new scenarios.In the second stage,a sample screening mechanism is used to select key samples,which are labeled through long-term simulation techniques for fine-tuning the model parameters.This allows for rapid model updates without relying on many labeled samples.This paper’s proposed model and update scheme have been simulated and verified on two node systems,the IEEE New England 10-machine 39-bus system and the IEEE 47-machine 140-bus system,demonstrating their effectiveness and reliability.展开更多
How to describe the austenite reverse transformation(ART)has always been considered as a key problem of controlling microstructures and mechanical properties in high-strength steels.So far,numerous studies have been c...How to describe the austenite reverse transformation(ART)has always been considered as a key problem of controlling microstructures and mechanical properties in high-strength steels.So far,numerous studies have been conducted,unfortunately,without fully considering diffusion of elements,interface migration,and interaction between trans-interface diffusion and interface migration,as well as synergy of thermodynamic and kinetic for interfacial migration.A more flexible modeling for the ART is herein developed using thermodynamic extremal principle,where the concept of trans-interface diffusion in two steps,i.e.,from the parent phase to the interface and from the interface to the product phase,as well as the Gibbs energy balance approach,was introduced to predict the behavior of interface migration and element trans-interface diffusion within the migrating interface.Subsequently,the thermodynamic driving force ΔG and the effective kinetic energy barrier Q_(eff) for the ART were also analytically performed,as well as a unified expression for so-called generalized stability(GS).It is demonstrated that the higher driving force in the ART generally results in the increased yield strength,while the larger GS tends to yield improved uniform elongation,thus forming a correspondence between the thermo-kinetics trade-off and the strength-ductility trade-off.Applying a proposed criterion of high ΔG-high GS,the present model can be adopted to design the ART,which will produce the austenite microstructure with high strength and high plasticity,as evidenced by the current experiments.展开更多
The efforts Xiamen has made in ecological protection over the last 20 years have helped it become a beautiful and clean city.TWENTY years ago,I had the opportunity to travel to the city of Xiamen in southeastern China...The efforts Xiamen has made in ecological protection over the last 20 years have helped it become a beautiful and clean city.TWENTY years ago,I had the opportunity to travel to the city of Xiamen in southeastern China’s Fujian Province.Unfortunately,due to the fact that I was in a rush,I did not have the chance to see the whole city.My memory of Xiamen was its pleasant climate and unforgettable beauty-I knew if I ever got the opportunity,I would revisit this place.Twenty years went by until I was able to return to this city again.After emerging from the airport,I realized that I had grown older,while Xiamen was becoming increasingly youthful and vibrant.What exactly had given this city such vitality?展开更多
BACKGROUND Malignant transformation(MT)of mature cystic teratoma(MCT)has a poor prognosis,especially in advanced cases.Concurrent chemoradiotherapy(CCRT)has an inhibitory effect on MT.CASE SUMMARY Herein,we present a ...BACKGROUND Malignant transformation(MT)of mature cystic teratoma(MCT)has a poor prognosis,especially in advanced cases.Concurrent chemoradiotherapy(CCRT)has an inhibitory effect on MT.CASE SUMMARY Herein,we present a case in which CCRT had a reduction effect preoperatively.A 73-year-old woman with pyelonephritis was referred to our hospital.Computed tomography revealed right hydronephrosis and a 6-cm pelvic mass.Endoscopic ultrasound-guided fine-needle biopsy(EUS-FNB)revealed squamous cell carci-noma.The patient was diagnosed with MT of MCT.Due to her poor general con-dition and renal malfunction,we selected CCRT,expecting fewer adverse effects.After CCRT,her performance status improved,and the tumor size was reduced;surgery was performed.Five months postoperatively,the patient developed dis-semination and lymph node metastases.Palliative chemotherapy was ineffective.She died 18 months after treatment initiation.CONCLUSION EUS-FNB was useful in the diagnosis of MT of MCT;CCRT suppressed the disea-se and improved quality of life.展开更多
Dear Editor,This letter is concerned with stability analysis and stabilization design for sampled-data based load frequency control(LFC) systems via a data-driven method. By describing the dynamic behavior of LFC syst...Dear Editor,This letter is concerned with stability analysis and stabilization design for sampled-data based load frequency control(LFC) systems via a data-driven method. By describing the dynamic behavior of LFC systems based on a data-based representation, a stability criterion is derived to obtain the admissible maximum sampling interval(MSI) for a given controller and a design condition of the PI-type controller is further developed to meet the required MSI. Finally, the effectiveness of the proposed methods is verified by a case study.展开更多
基金Funded by the Natural Science Foundation of Hebei Province(No.E2020209010)the Science and Technology Plan Project of Tangshan(No.19150225E)the Key R&D Projects of North China University of Science and Technology(No.ZD-ST-202301)。
文摘In view of the volume instability of steel slag aggregate leading to the quality problem of expansion damage in asphalt road construction,the 4.75-9.5 mm steel slag particles were treated by autoclaved carbonation technology,and the effects of the carbonation system(temperature and time)on the autoclaved pulverization rate,f-CaO content,and the relationship between them for the carbonated steel slag were investigated.In addition,the microstructure of the carbonated steel slag was analyzed by X-ray diffractometer(XRD),scanning electron microscope and energy dispersive spectrometer(SEM-EDS),metallographic microscope and X-ray fluorescence imaging spectrometer(XRF).The experimental results indicate that,under the initial CO_(2)pressure of 1.0 MPa,increasing the carbonation temperature leads to the increase in the crystal plane spacing of Ca(OH)_(2)that was generated by the hydration of minerals in steel slag,and promotes the transformation of carbonated CaCO_(3)from the orthorhombic system to the hexagonal system,resulting in the increase of the crystal planes spacing of them,meantime,accelerates the decomposition of RO phases and also the outward migration of Ca^(2+),Fe^(2+),and Mn^(2+)ions to cover and coat on the Si^(4+),Al^(3+)ions,and impels the formation of hydroxides such as Fe(OH)_(3)and the formation of carbonates such as Ca(Mg)CO_(3),FeCO_(3)and MnCO_(3).Carbonation at the temperature of 90℃for 3 h can reach the center of 4.75-9.5 mm steel slag particles.Meanwhile,the increase of temperature can promote the mineral reaction in steel slag,resulting in the fuzzy interface between mineral phases,increase of burrs,dispersion,crossover,reduction of grain size,and rearrangement of mineral particles.
基金supported by the National Natural Science Foundation of China(Nos.51974379,52274414)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+2 种基金the Project of National Science Fund for Excellent Young Scholars of China(No.52022111)the National Key R&D Program of China(No.2022YFD1700101)the Huxiang Youth Talent Support Program(No.2020RC3012)。
文摘Birnessite is ubiquitous in the natural environment where heavy metals are retained and easily transformed.The surface properties and structure of birnessite change with the changes in external environmental conditions,which also affects the fate of heavy metals.Clarifying the effect and mechanism of the birnessite phase transition process on heavy metals is the key to taking effective measures to prevent and control heavy metal pollution.Therefore,the four transformation pathways of birnessite are summarized first in this review.Second,the relationship between transformation pathways and environmental conditions is proposed.These relevant environmental conditions include abiotic(e.g.,co-existing ions,pH,oxygen pressure,temperature,electric field,light,aging,pressure)and biotic factors(e.g.,microorganisms,biomolecules).The phase transformation is achieved by the key intermediate of Mn(Ⅲ)through interlayer-condensation,folding,neutralizationdisproportionation,and dissolution-recrystallization mechanisms.The AOS(average oxidation state)of Mn and interlayer spacing are closely correlated with the phase transformation of birnessite.Last but not least,the mechanisms of heavy metals immobilization in the transformation process of birnessite are summed up.They involve isomorphous substitution,redox,complexation,hydration/dehydration,etc.The transformation of birnessite and its implication on heavy metals will be helpful for understanding and predicting the behavior of heavy metals and the crucial phase of manganese oxides/hydroxides in natural and engineered environments.
文摘The present work aims to stabilize the room temperature allotropic transition of ammonium nitrate(AN)particles utilizing a microencapsulation technique,which involves solvent/non-solvent in which nitrocellulose(NC)has been employed as a coating agent.The SEM micrographs revealed distinct features of both pure AN and NC,contrasting with the irregular granular surface topography of the coated AN particles,demonstrating the adherence of NC on the AN surface.Structural analysis via infrared spectroscopy(IR)demonstrated a successful association of AN and NC,with slight shifts observed in IR bands indicating interfacial interactions.Powder X-ray Diffraction(PXRD)analysis further elucidated the structural changes induced by the coating process,revealing that the NC coating altered the crystallization pattern of its pure form.Thermal analysis demonstrates distinct profiles for pure and coated AN,for which the coated sample exhibits a temperature increase and an enthalpy decrease of the room temperature allotropic transition by 6℃,and 36%,respectively.Furthermore,the presence of NC coating alters the intermolecular forces within the composite system,leading to a reduction in melting enthalpy of coated AN by~39%compared to pure AN.The thermal decomposition analysis shows a two-step thermolysis process for coated AN,with a significant increase in the released heat by about 78%accompanied by an increase in the activation barrier of NC and AN thermolysis,demonstrating a stabilized reactivity of the AN-NC particles.These findings highlight the synergistic effect of NC coating on AN particles,which contributed to a structural and reactive stabilization of both AN and NC,proving the potential application of NC-coated AN as a strategically advantageous oxidizer in composite solid propellant formulations.
基金support of the National Natural Science Foundation of China(No.52171063).
文摘Weathering steel exhibits excellent corrosion resistance and is widely used in bridges,towers,railways,highways,and other engineering projects that are exposed to the atmosphere for long periods of time.However,before the formation of stable rust layers,weathering steel is prone to liquid rust sagging and spattering,leading to environmental pollution and city appearance concerns.These factors limit the application and development of weathering steel.In this study,a rapid and environmentally friendly method was de-veloped by introducing alloying elements,specifically investigating the role of Sn in the rapid stabilization of rust layers in marine atmo-spheric environments.The rust layer formed on weathering low-alloy steel exposed to prolonged outdoor conditions and laboratory im-mersion experiments was explored using electron probe micro-analyzer(EPMA),micro-Raman,X-ray photoelectron spectroscopy(XPS),and electrochemical measurements.Results showed an optimal synergistic effect between Sn and Cr,which facilitated the accelerated densification of the rust layer.This beneficial effect enhanced the capability of the rust layer to resist Cl^(-)erosion and improved the protec-tion performance of the rust layer.
基金the financial support from the National Key R&D Program of China (No. 2021YFB3800102)the National Natural Science Foundation of China (Nos. 52102196 and 52302324)CASHIPS Director's Fund (Nos. YZJJ-GGZX-2022-01 and YZJJ202304-CX)。
文摘Although perovskite solar cells(PSCs) demonstrate outstanding power conversion efficiency(PCE), their practical applications are still limited by stability issues caused by various problems such as poor crystal quality triggered structural instability. Herein, to address the structural instability of perovskites, we introduced a polymer additive, poly-L-lysine hydrobromide(PLL), into the perovskite precursor to promote perovskite crystal growth, thereby constructing a stable crystal structure. The results show that the introduction of PLL modulates the colloidal aggregation state in the precursor solution, provides longer time for growth of perovskite and successfully realizes the formation of large-sized perovskite films with high crystallinity. More importantly, owing to its hydrophobic long-chain structure and the widespread distribution of C=O and NH on the chain, PLL firmly locks the perovskite crystals, enhancing their structural stability while blocking the intrusion of external factors such as water molecules, significantly enhances the overall stability of the device. The results show that the PLL-based PSC has negligible hysteresis and its PCE is improved from 22.20% to 23.66%. while the PLL-modified perovskite films and devices demonstrate excellent thermal and environmental stability. These findings highlight PLL as a promising additive for optimizing perovskite crystallization, offering guidance for fabricating efficient and stable photovoltaic devices.
文摘In the context of the digital transformation of vocational education,a quality evaluation index system has been constructed.Based on a questionnaire survey conducted among higher vocational colleges and enterprises in Hainan Province,it has been found that the quality of vocational education generally depends on the talent training program and professional construction at the macro level.At the meso level,the teacher level and teaching environment are critical,while at the micro level,the evaluation of talent training quality cannot be underestimated.Strategies for quality improvement in vocational education are proposed from the perspectives of talent training programs,major construction,teacher development,teaching environment,and talent training quality,all under the lens of digital transformation.
基金funded by the Key-Area Research and Development Program of Guangdong Province(Grant No.2022B0202070002)the Guangxi Science and Technology Major Program(Grant No.GuikeAA23023007-2)+1 种基金the Guangdong Province Modern Agricultural Industry Technology System Innovation Team Construction Project(2024CXTD19)Guangdong Basic and Applied Basic Research Foundation(Grant No.2023A1515010303)。
文摘Agrobacterium tumefaciens-mediated transformation has been widely adopted for plant genetic engineering and the study of gene function(Krenek et al.,2015).This method is prevalent in the genetic transformation of herbaceous plants,with notable applications in species such as Arabidopsis(Yin et al.,2024),soybean(Zhang et al.,2024),rice(Zhang et al.,2020),and Chinese cabbage(Li et al.,2021).However,its application in fruit trees is limited.This is primarily due to their long growth cycles and lack of rapid,efficient,and stable transgenic systems,which severely hinders foundational research involving plant genetic transformation(Mei et al.,2024).Furthermore,for subtropical fruit trees,the presence of recalcitrant seeds adds an extra layer of difficulty to genetic transformation(Umarani et al.,2015),as most methods rely on seed germination as a basis for transformation.
基金financially supported by the National Key Re-search and Development Program of China(No.2021YFB3702604)the National Natural Science Foundation of China(No.52174377)+1 种基金the Chongqing Natural Science Foundation Project(No.CSTB2023NSCQ-MSX0824)This work was also supported by the Shaanxi Materials Analysis&Research Center and the Analytical&Testing Center of NPU.
文摘Theβsolidifiedγ-TiAl alloy holds important application value in the aerospace industry,while its com-plex phase compositions and geometric structures pose challenges to its microstructure control during the thermal-mechanical process.The microstructure evolution of Ti-43Al-4Nb-1Mo-0.2B alloy at 1200℃/0.01 s−1 was investigated to clarify the coupling role of dynamic recrystallization(DRX)and phase transformation.The results revealed that the rate of DRX inα2+γlamellar colonies was comparatively slower than that inβo+γmixed structure,instead being accompanied by intense lamellar kinking and rotation.The initiation and development rates of DRX inα2,βo,andγphases decreased sequentially.The asynchronous DRX of the various geometric structures and phase compositions resulted in the un-even deformed microstructure,and the dynamic softening induced by lamellar kinking and rotation was replaced by strengthened DRX as strain increased.Additionally,the blockyα2 phase and the terminals ofα2 lamellae were the preferential DRX sites owing to the abundant activated slip systems.Theα2→βo transformation within lamellar colonies facilitated DRX and fragment ofα2 lamellae,while theα2→γtransformation promoted the decomposition ofα2 lamellae and DRX ofγlamellae.Moreover,the var-iedβo+γmixed structures underwent complicated evolution:(1)Theγ→βo transformation occurred at boundaries of lamellar colonies,followed by simultaneous DRX ofγlamellar terminals and neighboringβo phase;(2)DRX occurred earlier within the band-likeβo phase,with the delayed DRX in enclosedγphase;(3)DRX within theβo synapses and neighboringγphase was accelerated owing to generation of elastic stress field;(4)Dispersedβo particles triggered particle stimulated nucleation(PSN)ofγphase.Eventually,atomic diffusion along crystal defects inβo andγphases caused fracture of band-likeβo phase and formation of massiveβo particles,impeding grain boundary migration and hindering DRXed grain growth ofγphase.
基金supported by a research grant from the National University of Singapore to WQS(RP-3960366)a collaborative research grant from Sichuan Zhongke Organ Co.Ltd(Chengdu,China).
文摘Objectives:Cold-acclimated organisms accumulate low molecular weight organic solutes such as sugar alcohols and soluble sugars.This study aimed to compare the efficacy of five sugar alcohols and 14 soluble sugars in stabilizing proteins under freezing,freeze-drying,and air-drying stresses.Materials and methods:Glucose-6-Phosphate Dehydrogenase(G6PD)was used as the model protein.G6PD solutions with or without sugar alcohols and or sugars were subjected to freezing,freeze-drying,and air-drying stresses.The recovery of G6PD activity was measured to evaluate the protective efficacy of these compounds.Results:Without stabilizers,freezing G6PD at-20℃ or-80℃ reduced enzyme activity by around 24%,while freeze-drying or air-drying reduced activity by 90%-95%.Among the five sugar alcohols tested,pinitol,quebrachitol and sorbitol stabilized G6PD,whereas mannitol and myo-inositol destabilized it.Among 14 soluble sugars,trehalose and raffinose showed slightly lower enzyme recovery after repeated freeze-thaw cycles at-20℃.Most soluble sugars(except arabinose and xylose)protected G6PD during freeze-drying,with di-,tri-,and oligosaccharides generally outperforming monosaccharides.During air-drying,lactose was ineffective,while arabinose,galactose,and xylose were detrimental.Conclusion:The study highlights the diverse mechanisms of sugar alcohols and sugars in protein stabilization under stress,offering insights for formulating stable protein-and cell-based drugs.
基金This work was supported by the National Natural Science Foundation of China(Grant No.12272141)The financial support is gratefully acknowledged.
文摘The transformation from multibody models to lumped-parameter models is a crucial aspect of vehicle dynamics research.The velocity transformation method is adopted in this research,and the suspension multibody model is described using only one degree of freedom.It is found that the equivalent mass of the system is time-dependent during the simulation process,as observed in numerical simulations.Further symbolic calculations are conducted to derive the analytical form of the equivalent mass,and the results show that once the static parameters are determined,the equivalent mass of the suspension system is determined solely by the vertical position of the suspension upright,which reveals the kinematics characteristic of the equivalent mass of the suspension system.It is found that the equivalent mass experiences smaller changes when the suspension is compressed from the middle position,but larger changes when the suspension is extended.Furthermore,by comparing the multibody model,the lumped-parameter model with static mass,and the proposed lumped-parameter model considering the kinematics characteristic of the equivalent unsprung mass,the proposed model produces simulation results that more closely match the original multibody model than the model with static mass.The improvements in accuracy can be up to 20%under certain evaluation metrics.
文摘This study investigates the innovative reuse of sewage sludge with eco-friendly alkaline solutes to improve clayey soil without conventional cementitious binders.The unconfined compressive strength(UCS)was the main criterion to assess the quality and effectiveness of the proposed solutions,as this test was performed to measure the strength of the stabilized clay by varying binders’dosages and curing times.Moreover,the direct shear test(DST)was used to investigate the Mohr-Coulomb parameters of the treated soil.Microstructure observations of the natural and treated soil were conducted using scanning electron microscope(SEM),energy-dispersive spectroscopy(EDS),and FTIR.Furthermore,toxicity characteristic leaching procedure(TCLP)tests were performed on the treated soil to investigate the leachability of metals.According to the results,using 2.5%of sewage sludge activated by NaOH and Na_(2)SiO_(3)increases the UCS values from 176 kPa to 1.46 MPa after 7 d and 56 d of curing,respectively.The results of the DST indicate that sewage sludge as a precursor increases cohesion and enhances frictional resistance,thereby improving the Mohr-Coulomb parameters of the stabilized soil.The SEM micrographs show that alkali-activated sewage sludge increases the integrity and reduces the cavity volumes in the stabilized soil.Moreover,TCLP tests revealed that the solubility of metals in the treated soil alkaliactivated by sewage sludge significantly decreased.This study suggests that using sewage sludge can replace cement and lime in ground improvement,improve the circular economy,and reduce the carbon footprint of construction projects.
基金supported by the National Natural Science Foundation of China(No.52271089)the financial support from the C hina Postdoctoral Science Foundation(No.2023M732192)。
文摘This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic analyses.The results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without Co.Moreover,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6.The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair.Furthermore,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair.These findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.
基金Supported by the Natural Science Foundation of Heilongjiang Province(LH2024A025)。
文摘The effects of plasma screening on the ^(1)P^(o) resonance states of H-and He below the n=3 and n=4 thresholds of the respective subsystemsare investigated using the stabilization method and correlated exponential wave functions.Two plasma mediums,namely,the Debye plasma and quantum plasma environments are considered.The screened Coulomb potential(SCP)obtained from Debye-Hückel model is used to represent Debye plasma environments and the exponential cosine screened Coulomb potential(ECSCP)obtained from a modified Debye-Hückel model is used to represent quantum plasma environments.The resonance parameters(resonance positions and widths)are presented in terms of the screening parameters.
基金Supported by the Jiangsu Higher School Undergraduate Innovation and Entrepreneurship Training Program(202311117078Y)。
文摘In this paper we use Böcklund transformation to construct soliton solutions for a coupled KdV system.This system was first proposed by Wang in 2010.First we generalize the well-known Bäcklund transformation for the KdV equation to such coupled KdV system.Then from a trivial seed solution,we construct soliton solutions.We also give a nonlinear superposition formula,which allows us to generate multi-soliton solutions.
基金the financial support received from the Key Program of National Natural Science Foundation of China(No.52130406)the National Key R&D Program of China(Nos.2021YFC2901000 and 2022YFC2905800)+1 种基金the General Program of National Natural Science Foundation of China(No.52274253)Natural Science Foundation Innovation Group Project of Hubei Province,China(No.2023AFA044)。
文摘Hydrogen-based mineral phase transformation(HMPT)technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores.However,further research is needed to clarify the phase composition and floatability of rare earths obtained after HMPT owing to the associated phase transformations.This study explored the mineralogical characteristics and separation behavior of rare earths in HMPT-treated iron tailings.Process mineralogy studies conducted via BGRIMM process mineralogy analysis and X-ray diffraction revealed that the main valuable minerals in the tailings included rare-earth oxides(9.15wt%),monazite(5.31wt%),and fluorite(23.52wt%).The study also examined the impact of mineral liberation and gangue mineral intergrowth on flotation performance.Flotation tests achieved a rare-earth oxide(REO)grade of 74.12wt% with a recovery of 34.17% in open-circuit flotation,whereas closed-circuit flotation resulted in a REO grade of 60.27wt% with a recovery of 73%.Transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy revealed that monazite remained stable during the HMPT process,while bastnaesite was transformed into Ce_(7)O_(12)and CeF_(3),leading to increased collector consumption.Nonetheless,the HMPT process did not significantly affect the flotation performance of rare earths.The enrichment of fluorite in the tailings highlighted its further recovery potential.The integration of HMPT with magnetic separation and flotation presents an efficient strategy for recovering rare earths,iron,and fluorite from Bayan Obo ores.
基金the National Natural Science Foundation of China(5227-7084).
文摘With the continuous expansion and increasing complexity of power system scales,the binary classifica-tion for transient stability assessment in power systems can no longer meet the safety requirements of power system control and regulation.Therefore,this paper proposes a multi-class transient stability assessment model based on an improved Transformer.The model is designed with a dual-tower encoder structure:one encoder focuses on the time dependency of data,while the other focuses on the dynamic correlations between variables.Feature extraction is conducted from both time and variable perspectives to ensure the completeness of the feature extraction process,thereby enhancing the accuracy of multi-class evaluation in power systems.Additionally,this paper introduces a hybrid sampling strategy based on sample boundaries,which addresses the issue of sample imbalance by increasing the number of boundary samples in the minority class and reducing the number of non-boundary samples in the majority class.Considering the frequent changes in power grid topology or operation modes,this paper proposes a two-stage updating scheme based on self-supervised learning:In the first stage,self-supervised learning is employed to mine the structural information from unlabeled data in the target domain,enhancing the model’s generalization capability in new scenarios.In the second stage,a sample screening mechanism is used to select key samples,which are labeled through long-term simulation techniques for fine-tuning the model parameters.This allows for rapid model updates without relying on many labeled samples.This paper’s proposed model and update scheme have been simulated and verified on two node systems,the IEEE New England 10-machine 39-bus system and the IEEE 47-machine 140-bus system,demonstrating their effectiveness and reliability.
基金supported by the National Natural Science Foundation of China(Nos.52130110,52271116,52431002)the Fundamental Research Funds for the Central Universities(No.D5000220052)the Aeronautical Science Foundation of China(2023Z053053003).
文摘How to describe the austenite reverse transformation(ART)has always been considered as a key problem of controlling microstructures and mechanical properties in high-strength steels.So far,numerous studies have been conducted,unfortunately,without fully considering diffusion of elements,interface migration,and interaction between trans-interface diffusion and interface migration,as well as synergy of thermodynamic and kinetic for interfacial migration.A more flexible modeling for the ART is herein developed using thermodynamic extremal principle,where the concept of trans-interface diffusion in two steps,i.e.,from the parent phase to the interface and from the interface to the product phase,as well as the Gibbs energy balance approach,was introduced to predict the behavior of interface migration and element trans-interface diffusion within the migrating interface.Subsequently,the thermodynamic driving force ΔG and the effective kinetic energy barrier Q_(eff) for the ART were also analytically performed,as well as a unified expression for so-called generalized stability(GS).It is demonstrated that the higher driving force in the ART generally results in the increased yield strength,while the larger GS tends to yield improved uniform elongation,thus forming a correspondence between the thermo-kinetics trade-off and the strength-ductility trade-off.Applying a proposed criterion of high ΔG-high GS,the present model can be adopted to design the ART,which will produce the austenite microstructure with high strength and high plasticity,as evidenced by the current experiments.
文摘The efforts Xiamen has made in ecological protection over the last 20 years have helped it become a beautiful and clean city.TWENTY years ago,I had the opportunity to travel to the city of Xiamen in southeastern China’s Fujian Province.Unfortunately,due to the fact that I was in a rush,I did not have the chance to see the whole city.My memory of Xiamen was its pleasant climate and unforgettable beauty-I knew if I ever got the opportunity,I would revisit this place.Twenty years went by until I was able to return to this city again.After emerging from the airport,I realized that I had grown older,while Xiamen was becoming increasingly youthful and vibrant.What exactly had given this city such vitality?
文摘BACKGROUND Malignant transformation(MT)of mature cystic teratoma(MCT)has a poor prognosis,especially in advanced cases.Concurrent chemoradiotherapy(CCRT)has an inhibitory effect on MT.CASE SUMMARY Herein,we present a case in which CCRT had a reduction effect preoperatively.A 73-year-old woman with pyelonephritis was referred to our hospital.Computed tomography revealed right hydronephrosis and a 6-cm pelvic mass.Endoscopic ultrasound-guided fine-needle biopsy(EUS-FNB)revealed squamous cell carci-noma.The patient was diagnosed with MT of MCT.Due to her poor general con-dition and renal malfunction,we selected CCRT,expecting fewer adverse effects.After CCRT,her performance status improved,and the tumor size was reduced;surgery was performed.Five months postoperatively,the patient developed dis-semination and lymph node metastases.Palliative chemotherapy was ineffective.She died 18 months after treatment initiation.CONCLUSION EUS-FNB was useful in the diagnosis of MT of MCT;CCRT suppressed the disea-se and improved quality of life.
基金supported in part by the National Natural Science Foundation of China(62373337,62373333)the 111 Project(B17040)State Key Laboratory of Advanced Electromagnetic Technology(2024KF002)
文摘Dear Editor,This letter is concerned with stability analysis and stabilization design for sampled-data based load frequency control(LFC) systems via a data-driven method. By describing the dynamic behavior of LFC systems based on a data-based representation, a stability criterion is derived to obtain the admissible maximum sampling interval(MSI) for a given controller and a design condition of the PI-type controller is further developed to meet the required MSI. Finally, the effectiveness of the proposed methods is verified by a case study.
