This study aims to develop an accurate and robust machine learning model to predict the carbonation depth of fly ash concrete,overcoming the limitations of traditional predictive methods.Five ensemble-based models,suc...This study aims to develop an accurate and robust machine learning model to predict the carbonation depth of fly ash concrete,overcoming the limitations of traditional predictive methods.Five ensemble-based models,such as adaptive boosting(AdaBoost),categorical boosting(CatBoost),gradient boosting regressor(GBR),hist gradient boosting regressor(HistGBR),and extreme gradient boosting(XGBoost),were developed and optimized using 729 high-quality dataset points incorporating seven input parameters,including cement,CO_(2),exposure time,water-binder ratio,fly ash,curing time,and compressive strength.Several performance evaluation metrics were used to compare the models.The GBR model emerged as the best-performing model,based on high coefficient of determination(R^(2))values and balanced error metrics across both validation and testing datasets.While all models performed exceptionally well on the training data,GBR demonstrated superior generalization capability,with R^(2) values of 0.9438 on the validation set and 0.9310 on the testing set.Furthermore,its low mean squared error(MSE),root mean square error(RMSE),mean absolute error(MAE),and median absolute error(MdAE)confirmed its robustness and accuracy.Moreover,shapley additive explanations(SHAP)analysis enhanced the interpretability of predictions,highlighting the curing time and exposure time as the most critical drivers of carbonation depth.展开更多
Unmanned Aerial Vehicles(UAVs)in Flying Ad-Hoc Networks(FANETs)are widely used in both civilian and military fields,but they face severe security,trust,and privacy vulnerabilities due to their high mobility,dynamic to...Unmanned Aerial Vehicles(UAVs)in Flying Ad-Hoc Networks(FANETs)are widely used in both civilian and military fields,but they face severe security,trust,and privacy vulnerabilities due to their high mobility,dynamic topology,and open wireless channels.Existing security protocols for Mobile Ad-Hoc Networks(MANETs)cannot be directly applied to FANETs,as FANETs require lightweight,high real-time performance,and strong anonymity.The current FANETs security protocol cannot simultaneously meet the requirements of strong anonymity,high security,and low overhead in high dynamic and resource-constrained scenarios.To address these challenges,this paper proposes an Anonymous Authentication and Key Exchange Protocol(AAKE-OWA)for UAVs in FANETs based on OneWay Accumulators(OWA).During the UAV registration phase,the Key Management Center(KMC)generates an identity ticket for each UAV using OWA and transmits it securely to the UAV’s on-board tamper-proof module.In the key exchange phase,UAVs generate temporary authentication tickets with random numbers and compute the same session key leveraging the quasi-commutativity of OWA.For mutual anonymous authentication,UAVs encrypt random numbers with the session key and verify identities by comparing computed values with authentication values.Formal analysis using the Scyther tool confirms that the protocol resists identity spoofing,man-in-the-middle,and replay attacks.Through Burrows Abadi Needham(BAN)logic proof,it achieves mutual anonymity,prevents simulation and physical capture attacks,and ensures secure connectivity of 1.Experimental comparisons with existing protocols prove that the AAKE-OWA protocol has lower computational overhead,communication overhead,and storage overhead,making it more suitable for resource-constrained FANET scenarios.Performance comparison experiments show that,compared with other schemes,this scheme only requires 8 one-way accumulator operations and 4 symmetric encryption/decryption operations,with a total computational overhead as low as 2.3504 ms,a communication overhead of merely 1216 bits,and a storage overhead of 768 bits.We have achieved a reduction in computational costs from 6.3%to 90.3%,communication costs from 5.0%to 69.1%,and overall storage costs from 33%to 68%compared to existing solutions.It can meet the performance requirements of lightweight,real-time,and anonymity for unmanned aerial vehicles(UAVs)networks.展开更多
Recycling rare earth elements(REEs)from waste is necessary for an environmentally sustainable reuse and wastewater management approach.Na-A zeolite was synthesized from coal fly ash(CFA)and applied for Ce^(3+)adsorpti...Recycling rare earth elements(REEs)from waste is necessary for an environmentally sustainable reuse and wastewater management approach.Na-A zeolite was synthesized from coal fly ash(CFA)and applied for Ce^(3+)adsorption.Fourier transform infrared(FTIR)spectra show peaks at 790,500 and 467 cm^(-1),which are bond vibrations of Si-O-Si,Si with Al-O and Si-O-.The surface area is 15.88 m^(2)/g,with a pore size of 2.14 nm.SEM images show a cubic shape,which indicates the formation of zeolite.Field emission and energy disperse spectroscopy(EDS)shows the formation of Si,Al,Na,and O.Na-A zeolite was applied for Ce^(3+)adsorption.The optimum conditions for Ce^(3+)adsorption are 50 ppm concentration,360 min,and pH 6.The maximum adsorption capacity is 176.49 mg/g.Based on the results,it is found that the adsorption of Ce^(3+)by Na-A zeolite is pseudo-second-order.The desorption test using HNO_(3) is more effective than using HCl and H_(2)SO_(4).A desorption efficiency of 97.22%is obtained at 4 cycles.Adsorption test using real sample wastewater demonstrates an adsorption efficiency of 83.35%.展开更多
Teacher–student relationships play a vital role in improving college students’academic performance and the quality of higher education.However,empirical studies with substantial data-driven insights remain limited.T...Teacher–student relationships play a vital role in improving college students’academic performance and the quality of higher education.However,empirical studies with substantial data-driven insights remain limited.To address this gap,this study collected 3278 questionnaires from seven universities across four provinces in China to analyze the key factors affecting college students’academic performance.A machine learning framework,CQFOA-KELM,was developed by enhancing the Fruit Fly Optimization Algorithm(FOA)with Covariance Matrix Adaptation Evolution Strategy(CMAES)and Quadratic Approximation(QA).CQFOA significantly improved population diversity and was validated on the IEEE CEC2017 benchmark functions.The CQFOA-KELM model achieved an accuracy of 98.15%and a sensitivity of 98.53%in predicting college students’academic performance.Additionally,it effectively identified the key factors influencing academic performance through the feature selection process.展开更多
Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly as...Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly ash paste.We conducted mechanical tests and numerical simulations to understand the evolution of microstructure,and used environmental scanning electron microscopy(ESEM)and energy dispersive spectroscopy(EDS)techniques to analyze the microenvironments of the samples.The mechanical properties of fly ash paste under different activation conditions and the changes in the microstructure and composition were investigated.The results revealed that under conditions of low NaOH content(1%-3%),the strength of the sample increased significantly.When the content exceeded 4%,the rate of increase in strength decreased.Based on the results,the optimal NaOH content was identified,which was about 4%.A good activation effect,especially for short-term activation(3-7 d),was achieved using TEA under high doping conditions.The activation effect was poor for long-term strength after 28 days.The CaO content did not significantly affect the degree of activation achieved.The maximum effect was exerted when the content of CaO was 2%.The virtual cement and concrete testing laboratory(VCCTL)was used to simulate the hydration process,and the results revealed that the use of the three types of activators accelerated the formation of Ca(OH)_(2) in the system.The activators also corroded the surface of the fly ash particles,resulting in a pozzolanic reaction.The active substances in fly ash were released efficiently,and hydration was realized.The pores were filled with hydration products,and the microstructure changed to form a new frame of paste filling that helped improve the strength of fly ash paste.展开更多
In order to study the characteristics of pure fly ash-based geopolymer concrete(PFGC)conveniently,we used a machine learning method that can quantify the perception of characteristics to predict its compressive streng...In order to study the characteristics of pure fly ash-based geopolymer concrete(PFGC)conveniently,we used a machine learning method that can quantify the perception of characteristics to predict its compressive strength.In this study,505 groups of data were collected,and a new database of compressive strength of PFGC was constructed.In order to establish an accurate prediction model of compressive strength,five different types of machine learning networks were used for comparative analysis.The five machine learning models all showed good compressive strength prediction performance on PFGC.Among them,R2,MSE,RMSE and MAE of decision tree model(DT)are 0.99,1.58,1.25,and 0.25,respectively.While R2,MSE,RMSE and MAE of random forest model(RF)are 0.97,5.17,2.27 and 1.38,respectively.The two models have high prediction accuracy and outstanding generalization ability.In order to enhance the interpretability of model decision-making,we used importance ranking to obtain the perception of machine learning model to 13 variables.These 13 variables include chemical composition of fly ash(SiO_(2)/Al_(2)O_(3),Si/Al),the ratio of alkaline liquid to the binder,curing temperature,curing durations inside oven,fly ash dosage,fine aggregate dosage,coarse aggregate dosage,extra water dosage and sodium hydroxide dosage.Curing temperature,specimen ages and curing durations inside oven have the greatest influence on the prediction results,indicating that curing conditions have more prominent influence on the compressive strength of PFGC than ordinary Portland cement concrete.The importance of curing conditions of PFGC even exceeds that of the concrete mix proportion,due to the low reactivity of pure fly ash.展开更多
In order to adjust some properties of cement grout or concrete,some mineral admixtures are usually added in the preparation.Admixtures can reduce the cement consumption and save the cost,and also adjust the workabilit...In order to adjust some properties of cement grout or concrete,some mineral admixtures are usually added in the preparation.Admixtures can reduce the cement consumption and save the cost,and also adjust the workability of the material,improve the strength and durability of the cement stone,or reduce hydration heat of the composite cement.At present,the content of fly ash or slag is generally less than 50%among the composite cementitious materials that have been studied more,but there is little research on composite cementitious materials with large mineral admixture.In this paper,XRD,SEM,and adiabatic temperature rise tests were used to discuss hydration products and mechanism of composite cement grout with 90%content of fly ash and slag.The results show that the hydration of the composite cement grout is an alkali-activated hydration reaction,and the hydration products are mainly amorphous substances such as hydrated calcium silicate or hydrated calcium aluminate gel.The hydration reaction temperature rise is much lower than that of ordinary cement grout,and the time of the temperature peak is significantly delayed.展开更多
Microwave-curing and mechanical grinding of fly ash have both beenadopted as effective methods for improving the early-age strength of alkali-activated fly ash(AAFA)binders.This study combined these two approaches by ...Microwave-curing and mechanical grinding of fly ash have both beenadopted as effective methods for improving the early-age strength of alkali-activated fly ash(AAFA)binders.This study combined these two approaches by synthesizing AAFA using original,medium-fine,and ultrafine fly ash as precursors,and then specimens were cured with a five-stage temperature-controlled microwave.The compressive strength results indicate that the original AAFA develops the highest strength initially during microwave-curing,reaching 28 MPa at stage 2.Medium-fine AAFA exhibits the highest strength of 60 MPa when cured to stage 4-I,which is 26%higher than the peak strength of original AAFA.It is attributed to the significant rise in their specific surface area,which accelerates the dissolution of Si and Al from the precursor and facilitates the subsequent formation of N-A-S-H gels.Additionally,nanoscale zeolite crystals formed as secondary products fill the tiny gaps between amorphous products,thereby significantly improving their microstructure.In contrast,ultrafine fly ash,primarily composed of fragmented particles,necessitated a substantial amount of water,which adversely affects the absorption efficiency for microwave of AAFA specimens.Thus,ultrafine AAFA specimens consistently exhibit the lowest compressive strength.Specifically,at the end of curing,the compressive strength of these three specimens with microwave-curing is approximately 32%,59%,and 172%higher than that of the steam-cured sample,respectively.These findings demonstrate the compatibility of microwave-curing and fly ash refinement in enhancing the early compressive strength development of AAFA.展开更多
Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was c...Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was conducted among 60 mango farmers in 7 districts in Sierra Leone between June and August, 2022, to assess their perceptions regarding fruit fly pest status and the current management options adopted for the control of this pest. Semi-structured questions designed in an open and closed-ended fashion were used for the study. The majority (83%) of the farmers were already aware of the fruit fly problem in the country with 62% perceiving it to be very severe. The majority (60%) of farmers, however, demonstrated poor knowledge of identifying fruit fly species, especially Bactrocera dorsalis, Ceratitis capitata, and Ceratitis cosyra. Farmers were more conversant about the direct damage symptoms to host fruits and the economic impact of fruit flies. A total of 32% of growers took no action to control fruit flies on their farms. Sixty-nine percent (69%) of the farmers adopted cultural control measures, like practicing prompt harvesting, collection and disposal of infested fruits, and weeding to maintain better sanitary conditions on their farms. Recommended fruit fly management strategies such as the use of botanicals and resistant varieties were either unknown or inaccessible to growers. A total of 52% applied chemicals that were not recommended for the control of fruit flies without considering their environmental and health risks. It is important to train fruit growers to improve their capabilities for fruit fly management through extension agents that are appropriate for helping them acquire basic knowledge of fruit fly pests and their management.展开更多
This study was part of the framework that contributed not only to the improvement of thermal comfort in housing but also to the decarbonization of the construction and building materials industry. For this purpose, te...This study was part of the framework that contributed not only to the improvement of thermal comfort in housing but also to the decarbonization of the construction and building materials industry. For this purpose, terracotta brick seems to meet these needs. Thus, the objective of this work was to evaluate the influence of the incorporation of coal fly ash from a thermal power plant on the physical and mechanical properties of fired bricks from grey clay in the Thicky area of Senegal. The coal fly ash was incorporated into the raw clay material in proportions of 0, 5, 10, and 15 % by weight. These two raw materials were first characterized by X-ray fluorescence spectroscopy (XRF). The XRF analyses showed that the most abundant oxides in clay were SiO2 (55.034%) and Fe2O3 (10.155%). In coal fly ash, SiO2 (38.574%) is predominant. The ash also contained Al2O3 (7.717%) and alicano-earthy melting oxides such as CaO (9.271%) and MgO (7.298%) etc. These melting oxides were necessary to facilitate the formation of the liquid phase when baking platelets. The latter, when burned at a temperature of 880°C, were characterized by determining the number of physico-mechanical parameters, such as linear shrinkage during cooking, water absorption, fire loss and compressive strength. A Hierarchical Ascending Classification of these different parameters was performed and three classes were obtained. Class 1 with better compressive strength (6.358 MPa), was in sample A (5%). Class 2 consisted of sample D (reference) and had a higher plasticity index (28.51%) and water absorption rate (11.19%). Finally, class 3, which included samples B (10%) and C (15%), had very high shrinkage and fire losses compared to other platelets. These results highlighted the possibility of using up to 5% of the coal fly ash in the production of new fired bricks with good performance.展开更多
Municipal solid waste incineration fly ash(MSWI)is considered as one of the hazardous wastes and requires to be well disposed to reduce the contaminant to the environment.Reference to the production of coal fly ash(FA...Municipal solid waste incineration fly ash(MSWI)is considered as one of the hazardous wastes and requires to be well disposed to reduce the contaminant to the environment.Reference to the production of coal fly ash(FA)bricks,MSWI and FA were utilized to prepare autoclaved MSWI-FA block samples.Ultrasonic-assisted hydrothermal synthesis technology was used for production to explore the effect of ultrasonic pre-treatment.Compressive strength,dry density,and water absorption tests were conducted to determine the optimal ultrasonic parameters.Ultrasonic pre-treating mechanisms were investigated by SEM,FT-IR,particle size analysis,and BET.Furthermore,the micro-analyses of block samples were conducted.The heavy metal leaching concentration was studied to assess the environmental safety.The experimental results show that the ultrasonic pre-treating time,water bath temperature,and ultrasonic power of 3 h,30℃,and 840 W are the optimal,under which the compressive strength,dry density,and water absorption were 8.14 MPa,1417.48 kg/m^(3),and 0.38,respectively.It is shown that ultrasound destroys the surface structure of raw materials and smaller FA particles embed into MSWI.The particle size distribution of pre-treated raw materials mixture is wider and total pore volume is decreased by 6.3%.During hydrothermal processing,more Al-substituted tobermorite crystals are generated,which is the main source of higher strength and smaller pore volume of prepared block samples.The solidification/stabilization rates of Cu,Pb,and Zn increased by 30.77%,4.76%,and 35.29%,respectively.This study shows a feasible way to utilize MSWI as raw material for construction.展开更多
On September 12,2023,in a reply letter to Jeffrey Greene,Chairman of the Sino-American Aviation Heritage Foundation,and Flying Tigers veterans Harry Moyer and Mel McMullen,President Xi Jinping noted,"In the past,...On September 12,2023,in a reply letter to Jeffrey Greene,Chairman of the Sino-American Aviation Heritage Foundation,and Flying Tigers veterans Harry Moyer and Mel McMullen,President Xi Jinping noted,"In the past,our two peoples fought the Japanese fascists together,and forged a deep friendship that stood the test of blood and fre."展开更多
The fabrication of highly flame-retardant polyamide 6(PA6)composites is of great significance for expanding their practical applications.Herein,a new flame-retardant system(ADP/FA)was developed by combining aluminum d...The fabrication of highly flame-retardant polyamide 6(PA6)composites is of great significance for expanding their practical applications.Herein,a new flame-retardant system(ADP/FA)was developed by combining aluminum diethylphosphinate(ADP)with excellent flame retardancy and fly ash(FA),an economical and environmentally friendly industrial waste.Due to the synergistic flame-retardant effect of ADP/FA in the condensed phase and gas phase,the PA6 composite containing only 11 wt%of ADP/FA(mass ratio 93:7)obtained vertical burning(UL-94)tests V-0 rating with a limiting oxygen index(LOI)of 30.9%.To obtain the same flame-retardant level of PA6/ADP/FA-3,the loading amount of ADP alone was required 14 wt%.Compared with the PA6/ADP,the introduction of FA not only reduced the amount of flame retardant added but also inhibited the formation of molten droplets during combustion,greatly enhancing the fire safety of the PA6 composites.The flame-retardant performance of the ADP/FA system is superior to that of most current ADP-based synergistic strategies.In the meantime,the introduction of FA also significantly reduced the high smoke release caused by ADP flame retardant.The peak smoke production rate(pSPR)of the PA6 composite,from 0.221 m2⋅s-1(PA6/ADP)to 0.116 m2⋅s-1,represents a 47.5%decrease.This work provides a feasible solution for fabricating PA6 composites with excellent flame retardancy.展开更多
The widespread occurrence of carbapenem-resistant organisms has garnered significant public attention.Arthro-pods,including flies,are important vectors of multidrug-resistant bacteria.In this study,we reported the sim...The widespread occurrence of carbapenem-resistant organisms has garnered significant public attention.Arthro-pods,including flies,are important vectors of multidrug-resistant bacteria.In this study,we reported the simultane-ous carriage of four carbapenem-resistant isolates from different species,namely,Escherichia coli(E.coli),Providencia manganoxydans(P.manganoxydan),Myroides odoratimimus(M.odoratimimus)and Proteus mirabilis(P.mirabilis),from a single fly in China.These isolates were characterized through antimicrobial susceptibility testing,conjuga-tion assays,whole-genome sequencing,and bioinformatics analysis.M.odoratimimus showed intrinsic resistance to carbapenems.The mechanisms of carbapenem resistance in E.coli,P.manganoxydans,and P.mirabilis were due to the production of NDM-5,NDM-1 and NDM-1,respectively.Genetic context of the bla_(NDM) genes in these three isolates varied.The bla_(NDM-5) gene in E.coli was located on an IncHI2/HI2A multidrug-resistant plasmid,which was con-jugatively transferable.The bla_(NDM-1) gene in P.mirabilis resided on the pPM14-NDM_123k-like nonconjugative plasmid.The bla_(NDM-1) gene in P.manganoxydans was found in a nonconjugatively transferable,multidrug-resistant region.The results of this study enhance our understanding of the dissemination of carbapenem-resistant organisms and sug-gest the need for a more comprehensive approach to antibiotic resistance research encompassing humans,animals,and the environment.展开更多
The effects of isocyanate(IA)incorporation on the toughness and volume stability of AAFS were systematically investigated.Various IA dosages were introduced into AAFS,and their influence on mechanical properties,micro...The effects of isocyanate(IA)incorporation on the toughness and volume stability of AAFS were systematically investigated.Various IA dosages were introduced into AAFS,and their influence on mechanical properties,microstructure,and shrinkage behavior was evaluated.The experimental results indicate that,with the incorporation of 5%IA,the 28-day compressive strength reaches 48.6 MPa,the 56-day drying shrinkage decreases by 35.91%,and minimal cracking is observed in the ring test.Microstructural analyses using SEM,XRD,and FTIR reveal that IA reacts with water to form urethane and biuret,which crosslinks into a durable network structure.This network fills pores,reducing internal stresses and improving both toughness and volume stability.These findings offer new insights into optimizing alkali-activated materials for construction applications and provide a potential pathway for the development of more durable and stable geopolymers.展开更多
The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil im...The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.展开更多
Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant ...Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant strategic importance.In recent years,extensive research has been conducted on the mechanisms,optimization,and applications of FA-based road engineering materials.This review focuses on FA-based road engineering material systems,synthesizing previous studies from three perspectives:cement concrete pavement materials,asphalt mixture pavement materials,and stabilized soil road materials.The findings reveal that FA significantly enhances road material performance through its pozzolanic activity,micro-nano filling effects,and interfacial strengthening.In cement concrete systems,the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification.Integrating particle size optimization,nano-modification,and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems.For asphalt mixtures,leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion,while alkali activation further extends its application scope.In stabilized soil systems,FA enhances soil integrity by forming cementitious networks,with structural reinforcement achievable through alkali activation and composite stabilization.However,current research still faces unresolved challenges.These include elemental imbalances and performance limitations in single-FA-based road engineering materials,insufficient high-value applications of FA carbon sequestration technology in road materials,lack of systematic frameworks for environmental risk assessments of FA-based road systems,and constrained application scenarios for FA in road engineering.Future research should focus on innovating activation technologies to enhance the reactivity of FA,co-utilizing multi-source solid wastes,researching carbon sequestration technologies for FA-based road engineering materials,establishing environmental monitoring and evaluation systems,and promoting the application of FA in subgrade filling.The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction,supporting sustainable,lowcarbon,and high-quality development in road engineering.展开更多
Phenolic foam(PF)has attracted growing attention in plugging areas due to its lightweight,flame retardancy and high fillability,yet its friable character and high reaction temperature severely weaken its potentials to...Phenolic foam(PF)has attracted growing attention in plugging areas due to its lightweight,flame retardancy and high fillability,yet its friable character and high reaction temperature severely weaken its potentials toward practical coal mining applications.Herein,a novel phenolic composite material filled with modified fly ash(MFA)geopolymer has been proposed to address the above issues.By modifying fly ash(FA)particles with siloxanes,robust interfacial bonding between the organic PF polymer and inorganic geopolymer network has been established,which enables modulation of their micro-morphologies to optimize their macro performances.The foam structure of PF evolves from an open-cell to a closed-cell morphology with the incorporation of MFA,leading to a decreased pulverization ratio(41%)while enhanced mechanical properties(15%).Compared with neat PF,the composite exhibits faster gelation dynamics during curing,with a maximum reaction temperature as low as only 40°C.PF/MFA composite show high reliability against gas leakage during a laboratory designed coal mine plugging test.Furthermore,the formation of a silica hybrid char layer with higher graphitization degree and a multiple continuous closed-cell structure following the combustion of PF/MFA effectively inhibits the release of combustible volatiles and toxic gases.It is provided that this strategy of geopolymer filled polymer cross-linking networks with tunable morphology opens up an avenue for advanced mining phenolic filling materials.展开更多
Background Black soldier fly larvae meal(BSFLM)stands out as a promising nutritional resource due to its rich bioactive substances and favorable protein profile.Nonetheless,its potential to mitigate coccidia infection...Background Black soldier fly larvae meal(BSFLM)stands out as a promising nutritional resource due to its rich bioactive substances and favorable protein profile.Nonetheless,its potential to mitigate coccidia infection in broilers remains uncertain.This study aimed to evaluate the impact of partially defatted BSFLM(pBSFLM)on growth performance,nutrient utilization,and intestinal health,focusing on morphology,immunology,and cecal fermentation in coccidia-infected broilers.Methods Over the initial 13 d,480 newly-hatched Cobb 500 male birds were allocated to three diets with increasing pBSFLM concentrations(0,60,or 120 g/kg).At d 13 post hatching,chicks within each dietary group were further allotted to non-challenge or challenge subsets,generating six treatments in a 3×2 factorial arrangement.Challenged birds were orally administered oocysts of E.maxima,E.acervulina,and E.tenella(25,000:125,000:25,000).Results During the infection phase(d 13 to 19),linear interactions between Eimeria and pBSFLM were observed in gain to feed ratio(G:F)(P<0.05)and cecal interferon-γ(IFN-γ,P<0.05),with a tendency in cecal acetate concentration(P=0.06).A quadratic interaction was observed in crypt depth(CD,P<0.05).Incremental pBSFLM inclusion negatively affected G:F,CD,IFN-γ,and acetate productions in the ceca under coccidia challenge.Conversely in nonchallenged birds,the impact of pBSFLM varied from neutral(e.g.G:F)to potentially advantageous(e.g.acetate).Challenged birds exhibited decreased(P<0.01)BW,BW gain,feed intake(FI),and the apparent ileal digestibility and total tract nutrient utilization of DM,gross energy,and nitrogen(N).Eimeria challenge reduced(P<0.01)serum carotenoid concentrations,decreased the villus height to crypt depth ratio(VH:CD,P<0.01),and increased concentrations of branched-chain fatty acids,specifically isobutyrate(P=0.059)and isovalerate(P<0.05)in the cecum.Dietary pBSFLM addition linearly reduced(P<0.05)BW,FI,and N utilization.Tendencies(P<0.06)were observed where pBSFLM linearly decreased VH:CD and reduced goblet cell density.Conclusions Increasing pBSFLM supplementation,particularly at 12%,adversely affected growth,ileal morphology,cecal acetate production,and downregulated key cytokine expression in response to coccidia infection.展开更多
文摘This study aims to develop an accurate and robust machine learning model to predict the carbonation depth of fly ash concrete,overcoming the limitations of traditional predictive methods.Five ensemble-based models,such as adaptive boosting(AdaBoost),categorical boosting(CatBoost),gradient boosting regressor(GBR),hist gradient boosting regressor(HistGBR),and extreme gradient boosting(XGBoost),were developed and optimized using 729 high-quality dataset points incorporating seven input parameters,including cement,CO_(2),exposure time,water-binder ratio,fly ash,curing time,and compressive strength.Several performance evaluation metrics were used to compare the models.The GBR model emerged as the best-performing model,based on high coefficient of determination(R^(2))values and balanced error metrics across both validation and testing datasets.While all models performed exceptionally well on the training data,GBR demonstrated superior generalization capability,with R^(2) values of 0.9438 on the validation set and 0.9310 on the testing set.Furthermore,its low mean squared error(MSE),root mean square error(RMSE),mean absolute error(MAE),and median absolute error(MdAE)confirmed its robustness and accuracy.Moreover,shapley additive explanations(SHAP)analysis enhanced the interpretability of predictions,highlighting the curing time and exposure time as the most critical drivers of carbonation depth.
基金supported in part by National Natural Science Foundation of China(under Grant 61902163)the Jiangsu“Qing Lan Project”,Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Major Research Project:23KJA520007)Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.SJCX25_1303).
文摘Unmanned Aerial Vehicles(UAVs)in Flying Ad-Hoc Networks(FANETs)are widely used in both civilian and military fields,but they face severe security,trust,and privacy vulnerabilities due to their high mobility,dynamic topology,and open wireless channels.Existing security protocols for Mobile Ad-Hoc Networks(MANETs)cannot be directly applied to FANETs,as FANETs require lightweight,high real-time performance,and strong anonymity.The current FANETs security protocol cannot simultaneously meet the requirements of strong anonymity,high security,and low overhead in high dynamic and resource-constrained scenarios.To address these challenges,this paper proposes an Anonymous Authentication and Key Exchange Protocol(AAKE-OWA)for UAVs in FANETs based on OneWay Accumulators(OWA).During the UAV registration phase,the Key Management Center(KMC)generates an identity ticket for each UAV using OWA and transmits it securely to the UAV’s on-board tamper-proof module.In the key exchange phase,UAVs generate temporary authentication tickets with random numbers and compute the same session key leveraging the quasi-commutativity of OWA.For mutual anonymous authentication,UAVs encrypt random numbers with the session key and verify identities by comparing computed values with authentication values.Formal analysis using the Scyther tool confirms that the protocol resists identity spoofing,man-in-the-middle,and replay attacks.Through Burrows Abadi Needham(BAN)logic proof,it achieves mutual anonymity,prevents simulation and physical capture attacks,and ensures secure connectivity of 1.Experimental comparisons with existing protocols prove that the AAKE-OWA protocol has lower computational overhead,communication overhead,and storage overhead,making it more suitable for resource-constrained FANET scenarios.Performance comparison experiments show that,compared with other schemes,this scheme only requires 8 one-way accumulator operations and 4 symmetric encryption/decryption operations,with a total computational overhead as low as 2.3504 ms,a communication overhead of merely 1216 bits,and a storage overhead of 768 bits.We have achieved a reduction in computational costs from 6.3%to 90.3%,communication costs from 5.0%to 69.1%,and overall storage costs from 33%to 68%compared to existing solutions.It can meet the performance requirements of lightweight,real-time,and anonymity for unmanned aerial vehicles(UAVs)networks.
基金Project supported by Rumah Program 2023 and Net Zero Emission Program(1507/Ⅱ.7/HK.01.00/6/2023)a research facility from the National Research and Innovation Agency of Republic of Indonesia。
文摘Recycling rare earth elements(REEs)from waste is necessary for an environmentally sustainable reuse and wastewater management approach.Na-A zeolite was synthesized from coal fly ash(CFA)and applied for Ce^(3+)adsorption.Fourier transform infrared(FTIR)spectra show peaks at 790,500 and 467 cm^(-1),which are bond vibrations of Si-O-Si,Si with Al-O and Si-O-.The surface area is 15.88 m^(2)/g,with a pore size of 2.14 nm.SEM images show a cubic shape,which indicates the formation of zeolite.Field emission and energy disperse spectroscopy(EDS)shows the formation of Si,Al,Na,and O.Na-A zeolite was applied for Ce^(3+)adsorption.The optimum conditions for Ce^(3+)adsorption are 50 ppm concentration,360 min,and pH 6.The maximum adsorption capacity is 176.49 mg/g.Based on the results,it is found that the adsorption of Ce^(3+)by Na-A zeolite is pseudo-second-order.The desorption test using HNO_(3) is more effective than using HCl and H_(2)SO_(4).A desorption efficiency of 97.22%is obtained at 4 cycles.Adsorption test using real sample wastewater demonstrates an adsorption efficiency of 83.35%.
文摘Teacher–student relationships play a vital role in improving college students’academic performance and the quality of higher education.However,empirical studies with substantial data-driven insights remain limited.To address this gap,this study collected 3278 questionnaires from seven universities across four provinces in China to analyze the key factors affecting college students’academic performance.A machine learning framework,CQFOA-KELM,was developed by enhancing the Fruit Fly Optimization Algorithm(FOA)with Covariance Matrix Adaptation Evolution Strategy(CMAES)and Quadratic Approximation(QA).CQFOA significantly improved population diversity and was validated on the IEEE CEC2017 benchmark functions.The CQFOA-KELM model achieved an accuracy of 98.15%and a sensitivity of 98.53%in predicting college students’academic performance.Additionally,it effectively identified the key factors influencing academic performance through the feature selection process.
基金Supported by Yunnan Major Scientific and Technological Projects(No.202403AA080001)National Natural Science Foundation of China(No.52074137)Yunnan Fundamental Research Projects(No.202201AT070151)。
文摘Three types of activators such as sodium hydroxide,calcium oxide and triethanolamine(TEA)are used to establish different activation environments to address the problems associated with the process of activating fly ash paste.We conducted mechanical tests and numerical simulations to understand the evolution of microstructure,and used environmental scanning electron microscopy(ESEM)and energy dispersive spectroscopy(EDS)techniques to analyze the microenvironments of the samples.The mechanical properties of fly ash paste under different activation conditions and the changes in the microstructure and composition were investigated.The results revealed that under conditions of low NaOH content(1%-3%),the strength of the sample increased significantly.When the content exceeded 4%,the rate of increase in strength decreased.Based on the results,the optimal NaOH content was identified,which was about 4%.A good activation effect,especially for short-term activation(3-7 d),was achieved using TEA under high doping conditions.The activation effect was poor for long-term strength after 28 days.The CaO content did not significantly affect the degree of activation achieved.The maximum effect was exerted when the content of CaO was 2%.The virtual cement and concrete testing laboratory(VCCTL)was used to simulate the hydration process,and the results revealed that the use of the three types of activators accelerated the formation of Ca(OH)_(2) in the system.The activators also corroded the surface of the fly ash particles,resulting in a pozzolanic reaction.The active substances in fly ash were released efficiently,and hydration was realized.The pores were filled with hydration products,and the microstructure changed to form a new frame of paste filling that helped improve the strength of fly ash paste.
基金Funded by the Natural Science Foundation of China(No.52109168)。
文摘In order to study the characteristics of pure fly ash-based geopolymer concrete(PFGC)conveniently,we used a machine learning method that can quantify the perception of characteristics to predict its compressive strength.In this study,505 groups of data were collected,and a new database of compressive strength of PFGC was constructed.In order to establish an accurate prediction model of compressive strength,five different types of machine learning networks were used for comparative analysis.The five machine learning models all showed good compressive strength prediction performance on PFGC.Among them,R2,MSE,RMSE and MAE of decision tree model(DT)are 0.99,1.58,1.25,and 0.25,respectively.While R2,MSE,RMSE and MAE of random forest model(RF)are 0.97,5.17,2.27 and 1.38,respectively.The two models have high prediction accuracy and outstanding generalization ability.In order to enhance the interpretability of model decision-making,we used importance ranking to obtain the perception of machine learning model to 13 variables.These 13 variables include chemical composition of fly ash(SiO_(2)/Al_(2)O_(3),Si/Al),the ratio of alkaline liquid to the binder,curing temperature,curing durations inside oven,fly ash dosage,fine aggregate dosage,coarse aggregate dosage,extra water dosage and sodium hydroxide dosage.Curing temperature,specimen ages and curing durations inside oven have the greatest influence on the prediction results,indicating that curing conditions have more prominent influence on the compressive strength of PFGC than ordinary Portland cement concrete.The importance of curing conditions of PFGC even exceeds that of the concrete mix proportion,due to the low reactivity of pure fly ash.
文摘In order to adjust some properties of cement grout or concrete,some mineral admixtures are usually added in the preparation.Admixtures can reduce the cement consumption and save the cost,and also adjust the workability of the material,improve the strength and durability of the cement stone,or reduce hydration heat of the composite cement.At present,the content of fly ash or slag is generally less than 50%among the composite cementitious materials that have been studied more,but there is little research on composite cementitious materials with large mineral admixture.In this paper,XRD,SEM,and adiabatic temperature rise tests were used to discuss hydration products and mechanism of composite cement grout with 90%content of fly ash and slag.The results show that the hydration of the composite cement grout is an alkali-activated hydration reaction,and the hydration products are mainly amorphous substances such as hydrated calcium silicate or hydrated calcium aluminate gel.The hydration reaction temperature rise is much lower than that of ordinary cement grout,and the time of the temperature peak is significantly delayed.
文摘Microwave-curing and mechanical grinding of fly ash have both beenadopted as effective methods for improving the early-age strength of alkali-activated fly ash(AAFA)binders.This study combined these two approaches by synthesizing AAFA using original,medium-fine,and ultrafine fly ash as precursors,and then specimens were cured with a five-stage temperature-controlled microwave.The compressive strength results indicate that the original AAFA develops the highest strength initially during microwave-curing,reaching 28 MPa at stage 2.Medium-fine AAFA exhibits the highest strength of 60 MPa when cured to stage 4-I,which is 26%higher than the peak strength of original AAFA.It is attributed to the significant rise in their specific surface area,which accelerates the dissolution of Si and Al from the precursor and facilitates the subsequent formation of N-A-S-H gels.Additionally,nanoscale zeolite crystals formed as secondary products fill the tiny gaps between amorphous products,thereby significantly improving their microstructure.In contrast,ultrafine fly ash,primarily composed of fragmented particles,necessitated a substantial amount of water,which adversely affects the absorption efficiency for microwave of AAFA specimens.Thus,ultrafine AAFA specimens consistently exhibit the lowest compressive strength.Specifically,at the end of curing,the compressive strength of these three specimens with microwave-curing is approximately 32%,59%,and 172%higher than that of the steam-cured sample,respectively.These findings demonstrate the compatibility of microwave-curing and fly ash refinement in enhancing the early compressive strength development of AAFA.
文摘Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was conducted among 60 mango farmers in 7 districts in Sierra Leone between June and August, 2022, to assess their perceptions regarding fruit fly pest status and the current management options adopted for the control of this pest. Semi-structured questions designed in an open and closed-ended fashion were used for the study. The majority (83%) of the farmers were already aware of the fruit fly problem in the country with 62% perceiving it to be very severe. The majority (60%) of farmers, however, demonstrated poor knowledge of identifying fruit fly species, especially Bactrocera dorsalis, Ceratitis capitata, and Ceratitis cosyra. Farmers were more conversant about the direct damage symptoms to host fruits and the economic impact of fruit flies. A total of 32% of growers took no action to control fruit flies on their farms. Sixty-nine percent (69%) of the farmers adopted cultural control measures, like practicing prompt harvesting, collection and disposal of infested fruits, and weeding to maintain better sanitary conditions on their farms. Recommended fruit fly management strategies such as the use of botanicals and resistant varieties were either unknown or inaccessible to growers. A total of 52% applied chemicals that were not recommended for the control of fruit flies without considering their environmental and health risks. It is important to train fruit growers to improve their capabilities for fruit fly management through extension agents that are appropriate for helping them acquire basic knowledge of fruit fly pests and their management.
文摘This study was part of the framework that contributed not only to the improvement of thermal comfort in housing but also to the decarbonization of the construction and building materials industry. For this purpose, terracotta brick seems to meet these needs. Thus, the objective of this work was to evaluate the influence of the incorporation of coal fly ash from a thermal power plant on the physical and mechanical properties of fired bricks from grey clay in the Thicky area of Senegal. The coal fly ash was incorporated into the raw clay material in proportions of 0, 5, 10, and 15 % by weight. These two raw materials were first characterized by X-ray fluorescence spectroscopy (XRF). The XRF analyses showed that the most abundant oxides in clay were SiO2 (55.034%) and Fe2O3 (10.155%). In coal fly ash, SiO2 (38.574%) is predominant. The ash also contained Al2O3 (7.717%) and alicano-earthy melting oxides such as CaO (9.271%) and MgO (7.298%) etc. These melting oxides were necessary to facilitate the formation of the liquid phase when baking platelets. The latter, when burned at a temperature of 880°C, were characterized by determining the number of physico-mechanical parameters, such as linear shrinkage during cooking, water absorption, fire loss and compressive strength. A Hierarchical Ascending Classification of these different parameters was performed and three classes were obtained. Class 1 with better compressive strength (6.358 MPa), was in sample A (5%). Class 2 consisted of sample D (reference) and had a higher plasticity index (28.51%) and water absorption rate (11.19%). Finally, class 3, which included samples B (10%) and C (15%), had very high shrinkage and fire losses compared to other platelets. These results highlighted the possibility of using up to 5% of the coal fly ash in the production of new fired bricks with good performance.
基金Funded by the National Natural Science Foundation of China(No.52178241)the National Key Research and Development Program of China during the Fourteenth Five-Year Plan Period(No.2021YFB3802001)+1 种基金the Shanghai Science and Technology Innovation Action Plan(No.23D21201401)the Key Research and Development of the Shaanxi Province of China(No.2022GY-163)。
文摘Municipal solid waste incineration fly ash(MSWI)is considered as one of the hazardous wastes and requires to be well disposed to reduce the contaminant to the environment.Reference to the production of coal fly ash(FA)bricks,MSWI and FA were utilized to prepare autoclaved MSWI-FA block samples.Ultrasonic-assisted hydrothermal synthesis technology was used for production to explore the effect of ultrasonic pre-treatment.Compressive strength,dry density,and water absorption tests were conducted to determine the optimal ultrasonic parameters.Ultrasonic pre-treating mechanisms were investigated by SEM,FT-IR,particle size analysis,and BET.Furthermore,the micro-analyses of block samples were conducted.The heavy metal leaching concentration was studied to assess the environmental safety.The experimental results show that the ultrasonic pre-treating time,water bath temperature,and ultrasonic power of 3 h,30℃,and 840 W are the optimal,under which the compressive strength,dry density,and water absorption were 8.14 MPa,1417.48 kg/m^(3),and 0.38,respectively.It is shown that ultrasound destroys the surface structure of raw materials and smaller FA particles embed into MSWI.The particle size distribution of pre-treated raw materials mixture is wider and total pore volume is decreased by 6.3%.During hydrothermal processing,more Al-substituted tobermorite crystals are generated,which is the main source of higher strength and smaller pore volume of prepared block samples.The solidification/stabilization rates of Cu,Pb,and Zn increased by 30.77%,4.76%,and 35.29%,respectively.This study shows a feasible way to utilize MSWI as raw material for construction.
文摘On September 12,2023,in a reply letter to Jeffrey Greene,Chairman of the Sino-American Aviation Heritage Foundation,and Flying Tigers veterans Harry Moyer and Mel McMullen,President Xi Jinping noted,"In the past,our two peoples fought the Japanese fascists together,and forged a deep friendship that stood the test of blood and fre."
基金financially supported by the Natural Science Foundation of China(52173069)the Key Research and Development Projects in Heilongjiang Province(2024ZXDXA29)+1 种基金the Natural Science Foundation of Heilongjiang Province(LH2024B004)the Fundamental Research Funds for the Central Universities(ZHLJZR241700006).
文摘The fabrication of highly flame-retardant polyamide 6(PA6)composites is of great significance for expanding their practical applications.Herein,a new flame-retardant system(ADP/FA)was developed by combining aluminum diethylphosphinate(ADP)with excellent flame retardancy and fly ash(FA),an economical and environmentally friendly industrial waste.Due to the synergistic flame-retardant effect of ADP/FA in the condensed phase and gas phase,the PA6 composite containing only 11 wt%of ADP/FA(mass ratio 93:7)obtained vertical burning(UL-94)tests V-0 rating with a limiting oxygen index(LOI)of 30.9%.To obtain the same flame-retardant level of PA6/ADP/FA-3,the loading amount of ADP alone was required 14 wt%.Compared with the PA6/ADP,the introduction of FA not only reduced the amount of flame retardant added but also inhibited the formation of molten droplets during combustion,greatly enhancing the fire safety of the PA6 composites.The flame-retardant performance of the ADP/FA system is superior to that of most current ADP-based synergistic strategies.In the meantime,the introduction of FA also significantly reduced the high smoke release caused by ADP flame retardant.The peak smoke production rate(pSPR)of the PA6 composite,from 0.221 m2⋅s-1(PA6/ADP)to 0.116 m2⋅s-1,represents a 47.5%decrease.This work provides a feasible solution for fabricating PA6 composites with excellent flame retardancy.
基金funded by the National Natural Science Foundation of China(Grant No.32300156)the Natural Science Foundation of Jiangsu Province(Grant No.BK20220493).
文摘The widespread occurrence of carbapenem-resistant organisms has garnered significant public attention.Arthro-pods,including flies,are important vectors of multidrug-resistant bacteria.In this study,we reported the simultane-ous carriage of four carbapenem-resistant isolates from different species,namely,Escherichia coli(E.coli),Providencia manganoxydans(P.manganoxydan),Myroides odoratimimus(M.odoratimimus)and Proteus mirabilis(P.mirabilis),from a single fly in China.These isolates were characterized through antimicrobial susceptibility testing,conjuga-tion assays,whole-genome sequencing,and bioinformatics analysis.M.odoratimimus showed intrinsic resistance to carbapenems.The mechanisms of carbapenem resistance in E.coli,P.manganoxydans,and P.mirabilis were due to the production of NDM-5,NDM-1 and NDM-1,respectively.Genetic context of the bla_(NDM) genes in these three isolates varied.The bla_(NDM-5) gene in E.coli was located on an IncHI2/HI2A multidrug-resistant plasmid,which was con-jugatively transferable.The bla_(NDM-1) gene in P.mirabilis resided on the pPM14-NDM_123k-like nonconjugative plasmid.The bla_(NDM-1) gene in P.manganoxydans was found in a nonconjugatively transferable,multidrug-resistant region.The results of this study enhance our understanding of the dissemination of carbapenem-resistant organisms and sug-gest the need for a more comprehensive approach to antibiotic resistance research encompassing humans,animals,and the environment.
基金Funded by the National Key R&D Program of China(No.2022YFC3803400)。
文摘The effects of isocyanate(IA)incorporation on the toughness and volume stability of AAFS were systematically investigated.Various IA dosages were introduced into AAFS,and their influence on mechanical properties,microstructure,and shrinkage behavior was evaluated.The experimental results indicate that,with the incorporation of 5%IA,the 28-day compressive strength reaches 48.6 MPa,the 56-day drying shrinkage decreases by 35.91%,and minimal cracking is observed in the ring test.Microstructural analyses using SEM,XRD,and FTIR reveal that IA reacts with water to form urethane and biuret,which crosslinks into a durable network structure.This network fills pores,reducing internal stresses and improving both toughness and volume stability.These findings offer new insights into optimizing alkali-activated materials for construction applications and provide a potential pathway for the development of more durable and stable geopolymers.
基金supported by the Polish National Science Center(Grant No.2022/06/X/ST10/00320)received by Witold Tisler.
文摘The present study investigates the engineering properties of submerged organic silt(orSi)stabilized with F-class fly ash(FA),with and without the addition of an activator(CaO).The utilization of F-class FA for soil improvement is an important aspect of sustainable and environmentally-conscious geotechnical engineering when marginal usage of lime and concrete is of great interest to engineers and societies.Currently,discussion is predominantly focused on the positive aspects of using the F-class FA,with a paucity of emphasis on the negative aspects.To explore these features more thoroughly,a series of strength and compressibility tests was conducted.The sample preparation and curing methodology were chosen to replicate the in situ conditions where soil is surcharged and submerged in water.It was found that the incorporation of F-class FA without an activator reduces the undrained shear strength of submerged orSi by about 20%–25%and permanently prevents any thixotropic strength restoration.An increase in undrained shear strength is observed when lime(3%–6%)is added to the soil–FA mixture or when only lime(in the same amount of 3%–6%)is used.Consequently,F-class FA can be successfully used as a filler for slurries with minimum lime content in soil mixing methods.The F-class FA(with or without an activator)shifts the so-called“creep delay”in time,consequently reducing the total creep settlements.The shift of“creep delay”is more considerable for orSi stabilized with lime or with FA and lime as an activator,than for orSi stabilized with pure F-class FA.
基金supported by the following grants:Research on Key Technologies and Large-Scale Application of Resource Utilization of Industrial Solid Waste in Expressways(No.202300196)Science and Technology Development Plan Project of the Silk Road Economic Belt Innovation-Driven Development Pilot Zone and Wuchangshi National Independent Innovation Demonstration Zone(No.2023LQ03002)Research Initiation Program for High-Level Talents Introduced on a FullTime Basis in Ningxia,China(No.2024BEH04052).
文摘Fly ash(FA),a major solid waste from coal-fired industries,represents a critical pathway for the green disposal of bulk solid waste and the low-carbon construction of transportation infrastructure,holding significant strategic importance.In recent years,extensive research has been conducted on the mechanisms,optimization,and applications of FA-based road engineering materials.This review focuses on FA-based road engineering material systems,synthesizing previous studies from three perspectives:cement concrete pavement materials,asphalt mixture pavement materials,and stabilized soil road materials.The findings reveal that FA significantly enhances road material performance through its pozzolanic activity,micro-nano filling effects,and interfacial strengthening.In cement concrete systems,the synergistic interaction of pozzolanic reactions and microsphere filling achieves microstructural densification.Integrating particle size optimization,nano-modification,and alkali activation techniques can overcome the mechanical strength and durability limitations of traditional FA systems.For asphalt mixtures,leveraging FA’s porous adsorption characteristics and chemical bonding effects optimizes the asphalt-aggregate interface adhesion,while alkali activation further extends its application scope.In stabilized soil systems,FA enhances soil integrity by forming cementitious networks,with structural reinforcement achievable through alkali activation and composite stabilization.However,current research still faces unresolved challenges.These include elemental imbalances and performance limitations in single-FA-based road engineering materials,insufficient high-value applications of FA carbon sequestration technology in road materials,lack of systematic frameworks for environmental risk assessments of FA-based road systems,and constrained application scenarios for FA in road engineering.Future research should focus on innovating activation technologies to enhance the reactivity of FA,co-utilizing multi-source solid wastes,researching carbon sequestration technologies for FA-based road engineering materials,establishing environmental monitoring and evaluation systems,and promoting the application of FA in subgrade filling.The conclusions provide comprehensive insights for industrial solid waste recycling and low-carbon road construction,supporting sustainable,lowcarbon,and high-quality development in road engineering.
基金supported by the National Natural Science Foundation of China(No.U22A20151)Taiyuan Major Science and Technology Project in 2021.
文摘Phenolic foam(PF)has attracted growing attention in plugging areas due to its lightweight,flame retardancy and high fillability,yet its friable character and high reaction temperature severely weaken its potentials toward practical coal mining applications.Herein,a novel phenolic composite material filled with modified fly ash(MFA)geopolymer has been proposed to address the above issues.By modifying fly ash(FA)particles with siloxanes,robust interfacial bonding between the organic PF polymer and inorganic geopolymer network has been established,which enables modulation of their micro-morphologies to optimize their macro performances.The foam structure of PF evolves from an open-cell to a closed-cell morphology with the incorporation of MFA,leading to a decreased pulverization ratio(41%)while enhanced mechanical properties(15%).Compared with neat PF,the composite exhibits faster gelation dynamics during curing,with a maximum reaction temperature as low as only 40°C.PF/MFA composite show high reliability against gas leakage during a laboratory designed coal mine plugging test.Furthermore,the formation of a silica hybrid char layer with higher graphitization degree and a multiple continuous closed-cell structure following the combustion of PF/MFA effectively inhibits the release of combustible volatiles and toxic gases.It is provided that this strategy of geopolymer filled polymer cross-linking networks with tunable morphology opens up an avenue for advanced mining phenolic filling materials.
文摘Background Black soldier fly larvae meal(BSFLM)stands out as a promising nutritional resource due to its rich bioactive substances and favorable protein profile.Nonetheless,its potential to mitigate coccidia infection in broilers remains uncertain.This study aimed to evaluate the impact of partially defatted BSFLM(pBSFLM)on growth performance,nutrient utilization,and intestinal health,focusing on morphology,immunology,and cecal fermentation in coccidia-infected broilers.Methods Over the initial 13 d,480 newly-hatched Cobb 500 male birds were allocated to three diets with increasing pBSFLM concentrations(0,60,or 120 g/kg).At d 13 post hatching,chicks within each dietary group were further allotted to non-challenge or challenge subsets,generating six treatments in a 3×2 factorial arrangement.Challenged birds were orally administered oocysts of E.maxima,E.acervulina,and E.tenella(25,000:125,000:25,000).Results During the infection phase(d 13 to 19),linear interactions between Eimeria and pBSFLM were observed in gain to feed ratio(G:F)(P<0.05)and cecal interferon-γ(IFN-γ,P<0.05),with a tendency in cecal acetate concentration(P=0.06).A quadratic interaction was observed in crypt depth(CD,P<0.05).Incremental pBSFLM inclusion negatively affected G:F,CD,IFN-γ,and acetate productions in the ceca under coccidia challenge.Conversely in nonchallenged birds,the impact of pBSFLM varied from neutral(e.g.G:F)to potentially advantageous(e.g.acetate).Challenged birds exhibited decreased(P<0.01)BW,BW gain,feed intake(FI),and the apparent ileal digestibility and total tract nutrient utilization of DM,gross energy,and nitrogen(N).Eimeria challenge reduced(P<0.01)serum carotenoid concentrations,decreased the villus height to crypt depth ratio(VH:CD,P<0.01),and increased concentrations of branched-chain fatty acids,specifically isobutyrate(P=0.059)and isovalerate(P<0.05)in the cecum.Dietary pBSFLM addition linearly reduced(P<0.05)BW,FI,and N utilization.Tendencies(P<0.06)were observed where pBSFLM linearly decreased VH:CD and reduced goblet cell density.Conclusions Increasing pBSFLM supplementation,particularly at 12%,adversely affected growth,ileal morphology,cecal acetate production,and downregulated key cytokine expression in response to coccidia infection.
