The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate （OT） as th...The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate （OT） as the dispersant at a dispersant/fiber mass ratio of 0.15：1, dispersing for 30 min at a water/solid mass ratio of 20：1. The prepared nanofibers were characterized with X-ray diffraction （XRD）, scanning electron microscope （SEM）, and transmission electron microscope （TEM）. It is shown that the prepared single brucite nanofiber is around 30 nm in diameter and the talus of the nonsingle brucite nanofibers is about 50-150 nm in diameter. Natural brucite mineral fibers were treated by the dispersion method to obtain nanomaterials. These fibers have significant advantages over artificial nanofibers both in yield and in cost.展开更多
Fibrous bmcite has very unique structure and physical properties. Brucite fibers were exfoliated into single nanofibers by using dioctyl sodium sulfosuccinate （AOT） as a dispersant through mechanical agitation and u...Fibrous bmcite has very unique structure and physical properties. Brucite fibers were exfoliated into single nanofibers by using dioctyl sodium sulfosuccinate （AOT） as a dispersant through mechanical agitation and ultrasonic dispersion; and then, the nanofibers were modified by stearic acid and （3-aminopropyl）triethoxysilane （y-APS） compound modification agent. The nanofibers were characterized by using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR）, and thermal gravimetric analysis. It is found that AOT has good effect on the dispersion. The single fiber has a consis- tent morphology, and fibrous bmcite is dispersed and modified without destroying the crystal structure. Infrared and thermal analysis shows that the surface modification of fibrous brucite is achieved by forming chemical bonds between the coupling agent and magnesium hydroxide.展开更多
Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most inte...Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most interesting result is the temperature dependence of the line broadenings at T <400 K, with the negative velocity line always more broadened than the positive one. A possible explanation of these systematic broadenings is the presence of a small magnetic perturbation in brucite.展开更多
The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of ma...The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharprise of the adsorption amount of Pb^(2+) on brucite. The synergism of buffering and adsorptioncapacities of brucite is responsible for the removal of Pb^(2+) from the aqueous solution. Thecoexistence of Cu^(2+) with Pb^(2+) causes a decrease of their adsorption on brucite due to acompetition for surface sites and brucite exhibits a higher adsorption capacity for Pb^(2+) than forCu^(2+). The percentage adsorption of Pb^(2+) on brucite could reach 96.38 percent, 97.20 percentand 94.09 percent respectively with the initial pH of the suspension pH_i = 1.76 (initial Pb^(2+)concentration [Pb^(2+)]_i = 20 mumol/L), 1.82 ([Pb^(2+)]_i = 100 mumol/L) and 1.84 ([Pb^(2+)]_i =500 mumol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^(2+)removal from polluted acidic water.展开更多
Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of steari...Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of stearic acid on fibrous brucite and the induced changes in surface properties were studied by using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,infrared spectroscopy（IR）,Raman spectroscopy and thermo-gravimetric analysis（TGA）.XRD analysis indicates that the modification of fibrous brucite with stearic acid does not cause any changes in the structure of fibrous brucite mineral.Spectroscopy and thermal analysis show that the surfactant molecules are not only directly adsorbed on the surface of the mineral,but also chemisorbed on mineral surface by forming chemical bonds between the modifier and magnesium hydroxide.展开更多
Hydrous minerals within the subducting oceanic slab are important hosts for water.Clarification of the stability field of hydrous minerals helps to understand transport and distribution of water from the surface to th...Hydrous minerals within the subducting oceanic slab are important hosts for water.Clarification of the stability field of hydrous minerals helps to understand transport and distribution of water from the surface to the Earth’s interior.We investigated the stability of brucite,a prototype of hydrous minerals,by means of electrical conductivity measurements in both open and closed systems at 3 GPa and temperatures up to 1300 K.Dramatic increase of conductivity in association with characteristic impedance spectra suggests that partial dehydration of single-crystal brucite in the open system with a low water fugacity occurs at 950 K,which is about 300 K lower than those previously defined by phase equilibrium experiments in the closed system.By contrast,brucite completely dehydrates at 1300 K in the closed system,consistent with previous studies.Partial dehydration may generate a highly defective structure but does not lead to the breakdown of brucite to periclase and water immediately.Water activity plays a key role in the stability of hydrous minerals.Low water activity(a H_(2)O)caused by the high wetting behavior of the subducted oceanic slab at the transition zone depth may cause the partial dehydration of the dense hydrous magnesium silicates(DHMSs),which significantly reduces the temperature stability of DHMS(this mechanism has been confirmed by previous study on super hydrous phase B).As a result,the transition zone may serve as a‘dead zone’for DHMSs,and most water will be stored in wadsleyite and ringwoodite in the transition zone.展开更多
A Fe-containing mesoporous silica has been synthesized at room temperature using alkylamine as templating surfactant; XRD, IR, ESR and Si-29 MAS NMR spectra provided evidence of the presence of framework and non-frame...A Fe-containing mesoporous silica has been synthesized at room temperature using alkylamine as templating surfactant; XRD, IR, ESR and Si-29 MAS NMR spectra provided evidence of the presence of framework and non-framework iron(III) in Fe-HMS material.展开更多
Background Our previous studies demonstrated that divalent organic iron(Fe)proteinate sources with higher complexation or chelation strengths as expressed by the greater quotient of formation(Qf)values displayed highe...Background Our previous studies demonstrated that divalent organic iron(Fe)proteinate sources with higher complexation or chelation strengths as expressed by the greater quotient of formation(Qf)values displayed higher Fe bioavailabilities for broilers.Sodium iron ethylenediaminetetraacetate(NaFeEDTA)is a trivalent organic Fe source with the strongest chelating ligand EDTA.However,the bioavailability of Fe when administered as NaFeEDTA in broilers and other agricultural animals remains untested.Herein,the chemical characteristics of 12 NaFeEDTA products were determined.Of these,one feed grade NaFeEDTA(Qf=2.07×10^(8)),one food grade NaFeEDTA(Qf=3.31×10^(8)),and one Fe proteinate with an extremely strong chelation strength(Fe-Prot ES,Qf value=8,590)were selected.Their bioavailabilities relative to Fe sulfate(FeSO_(4)·7H_(2)O)for broilers fed with a conventional corn-soybean meal diet were evaluated during d 1 to 21 by investigating the effects of the above Fe sources and added Fe levels on the growth performance,hematological indices,Fe contents,activities and gene expressions of Fe-containing enzymes in various tissues of broilers.Results NaFeEDTA sources varied greatly in their chemical characteristics.Plasma Fe concentration(PI),transferrin saturation(TS),liver Fe content,succinate dehydrogenase(SDH)activities in liver,heart,and kidney,catalase(CAT)activity in liver,and SDH mRNA expressions in liver and kidney increased linearly(P<0.05)with increasing levels of Fe supplementation.However,differences among Fe sources were detected(P<0.05)only for PI,liver Fe content,CAT activity in liver,SDH activities in heart and kidney,and SDH mRNA expressions in liver and kidney.Based on slope ratios from multiple linear regressions of the above indices on daily dietary analyzed Fe intake,the average bioavailabilities of Fe-Prot ES,feed grade NaFeEDTA,and food grade NaFeEDTA relative to the inorganic FeSO_(4)·7H_(2)O(100%)for broilers were 139%,155%,and 166%,respectively.Conclusions The bioavailabilities of organic Fe sources relative to FeSO_(4)·7H_(2)O were closely related to their Qf values,and NaFeEDTA sources with higher Qf values showed higher Fe bioavailabilities for broilers fed with a conventional corn-soybean meal diet.展开更多
Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period ...Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period were 64±38 and 89±49μg/m~3,respectively,and NO_(2)and particulate matter were high compared with most other regions of China.The Fecontaining particles were divided into seven categories with different mass spectra,sources and aging characteristics.The highest contribution was from Fe mixed with carbonaceous components(Fe-C,23.1%)particles.Fe was more mixed with sulfate than nitrate and therefore the contribution of Fe mixed with sulfate(Fe-S,20.7%)particles was higher than that of Fe mixed with nitrate(Fe-N,12.5%)particles.The contributions from Fe-containing particles related to primary combustion were high in the small particle size range,whereas aged Fecontaining particles and dust-related particles were mostly found in the coarse particle size range.The air masses mainly originated from the west and east of Chengdu,and the corresponding PM_(2.5)concentrations were 79±36 and 55±36μg/m~3,respectively.The west and east air masses showed stronger contributions of Fe-containing particles related to biomass burning(Fe-B)and fossil fuel combustion(Fe-C and Fe-S)particles,respectively.The southwest area contributed the most Fe-containing particles.Future assessments of the effects of Fe-containing particles during heavy pollution period should pay more attention to Fe-C and Fe-S particles.Emission-reduction of Fe-containing particles should consider both local emissions and short-distance transmission from the surrounding areas.展开更多
Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semicond...Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.展开更多
Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ignored.Gd_(2)Zr_(2)O_(7)TBCs are famous...Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ignored.Gd_(2)Zr_(2)O_(7)TBCs are famous for their excellent CMAS resistance.In this study,the characteristics of Fe-containing environmental sediments(CMAS-Fe)and their corrosiveness to Gd_(2)Zr_(2)O_(7)coatings were investigated.Four types of CMAS-Fe glass with different Fe contents were fabricated.Their melting points were measured to be 1322–1344℃,and the high-temperature viscosity showed a decreasing trend with increasing Fe contents.The corrosion behavior of four types of CMAS-Fe to Gd_(2)Zr_(2)O_(7)coatings at 1350℃was investigated.At the initial corrosion stage(0.1 h),anorthite was precipitated in CMAS-Fe with a high Ca:Si ratio,while Fe-garnet was formed in the melt with the highest Fe content.Prolonging the corrosion time resulted in the formation of a reaction layer,which exhibited an interpenetrating network composed of Gd-oxyapatite,ZrO_(2),and residual CMAS-Fe.Some spinel was precipitated within the reaction layer.After 1 h or even longer time,the reaction layers tended to be stable and compact,which had comparable hardness and fracture toughness to those of Gd_(2)Zr_(2)O_(7)coatings.Under the cyclic CMAS-Fe attack,the residual CMAS-Fe in the interpenetrating network provided a pathway for the redeposited CMAS-Fe infiltration,resulting in the continuous growth of the reaction layer.As a result,the Gd_(2)Zr_(2)O_(7)coatings had a large consumption in the thickness,degrading the coating performance.Therefore,the Gd_(2)Zr_(2)O_(7)coatings exhibit unsatisfactory corrosion resistance to CMAS-Fe attack.展开更多
To achieve efficient flotation separation of brucite and calcite,flotation separation experiments were conducted on two minerals using dodecylamine(DDA)as the collector and potassium dihydrogen phosphate(PDP)as the re...To achieve efficient flotation separation of brucite and calcite,flotation separation experiments were conducted on two minerals using dodecylamine(DDA)as the collector and potassium dihydrogen phosphate(PDP)as the regulator.The action mechanism of DDA and PDP was explored through contact angle measurement,zeta potential detection,solution chemistry calculation,FTIR analysis,and XPS detection.The flotation results showed that when DDA dosage was 35 mg/L and PDP dosage was 40 mg/L,the maximum floating difference between brucite and calcite was 79.81%,and the selectivity separation index was 6.46.The detection analysis showed that the main dissolved component HPO_(4)^(2−)of PDP is selectively strongly adsorbed on the Ca site on the surface of calcite,promoting the adsorption of the main dissolved component RNH_(3)^(+)of DDA on calcite surface,while brucite is basically not affected by PDP.Therefore,PDP is an effective regulator for the reverse flotation separation of brucite and calcite in DDA system.展开更多
基金This study was financially supported by the National High-Tech Research and Development Program of China (No.2003AA302610)
文摘The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate （OT） as the dispersant at a dispersant/fiber mass ratio of 0.15：1, dispersing for 30 min at a water/solid mass ratio of 20：1. The prepared nanofibers were characterized with X-ray diffraction （XRD）, scanning electron microscope （SEM）, and transmission electron microscope （TEM）. It is shown that the prepared single brucite nanofiber is around 30 nm in diameter and the talus of the nonsingle brucite nanofibers is about 50-150 nm in diameter. Natural brucite mineral fibers were treated by the dispersion method to obtain nanomaterials. These fibers have significant advantages over artificial nanofibers both in yield and in cost.
基金financially supported by the National Natural Science Foundation of China(Nos.51274015 and 40972027)
文摘Fibrous bmcite has very unique structure and physical properties. Brucite fibers were exfoliated into single nanofibers by using dioctyl sodium sulfosuccinate （AOT） as a dispersant through mechanical agitation and ultrasonic dispersion; and then, the nanofibers were modified by stearic acid and （3-aminopropyl）triethoxysilane （y-APS） compound modification agent. The nanofibers were characterized by using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR）, and thermal gravimetric analysis. It is found that AOT has good effect on the dispersion. The single fiber has a consis- tent morphology, and fibrous bmcite is dispersed and modified without destroying the crystal structure. Infrared and thermal analysis shows that the surface modification of fibrous brucite is achieved by forming chemical bonds between the coupling agent and magnesium hydroxide.
文摘Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most interesting result is the temperature dependence of the line broadenings at T <400 K, with the negative velocity line always more broadened than the positive one. A possible explanation of these systematic broadenings is the presence of a small magnetic perturbation in brucite.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50272008)Talent Training Program of Beijing (No. 2003A09)
文摘The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharprise of the adsorption amount of Pb^(2+) on brucite. The synergism of buffering and adsorptioncapacities of brucite is responsible for the removal of Pb^(2+) from the aqueous solution. Thecoexistence of Cu^(2+) with Pb^(2+) causes a decrease of their adsorption on brucite due to acompetition for surface sites and brucite exhibits a higher adsorption capacity for Pb^(2+) than forCu^(2+). The percentage adsorption of Pb^(2+) on brucite could reach 96.38 percent, 97.20 percentand 94.09 percent respectively with the initial pH of the suspension pH_i = 1.76 (initial Pb^(2+)concentration [Pb^(2+)]_i = 20 mumol/L), 1.82 ([Pb^(2+)]_i = 100 mumol/L) and 1.84 ([Pb^(2+)]_i =500 mumol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^(2+)removal from polluted acidic water.
基金Funded by National Natural Science Foundation of China(No.51274015)
文摘Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of stearic acid on fibrous brucite and the induced changes in surface properties were studied by using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,infrared spectroscopy（IR）,Raman spectroscopy and thermo-gravimetric analysis（TGA）.XRD analysis indicates that the modification of fibrous brucite with stearic acid does not cause any changes in the structure of fibrous brucite mineral.Spectroscopy and thermal analysis show that the surfactant molecules are not only directly adsorbed on the surface of the mineral,but also chemisorbed on mineral surface by forming chemical bonds between the modifier and magnesium hydroxide.
基金supported by CAS“Light of West China”program(Y9CR026 to X.G.)the National Natural Science Foundation of China(442072051)supported by the Ministry of Education,Culture,Sports,Science,and Technology of the Japanese Government,Grant Numbers,15H05827 and 17H01155 to T.Y.
文摘Hydrous minerals within the subducting oceanic slab are important hosts for water.Clarification of the stability field of hydrous minerals helps to understand transport and distribution of water from the surface to the Earth’s interior.We investigated the stability of brucite,a prototype of hydrous minerals,by means of electrical conductivity measurements in both open and closed systems at 3 GPa and temperatures up to 1300 K.Dramatic increase of conductivity in association with characteristic impedance spectra suggests that partial dehydration of single-crystal brucite in the open system with a low water fugacity occurs at 950 K,which is about 300 K lower than those previously defined by phase equilibrium experiments in the closed system.By contrast,brucite completely dehydrates at 1300 K in the closed system,consistent with previous studies.Partial dehydration may generate a highly defective structure but does not lead to the breakdown of brucite to periclase and water immediately.Water activity plays a key role in the stability of hydrous minerals.Low water activity(a H_(2)O)caused by the high wetting behavior of the subducted oceanic slab at the transition zone depth may cause the partial dehydration of the dense hydrous magnesium silicates(DHMSs),which significantly reduces the temperature stability of DHMS(this mechanism has been confirmed by previous study on super hydrous phase B).As a result,the transition zone may serve as a‘dead zone’for DHMSs,and most water will be stored in wadsleyite and ringwoodite in the transition zone.
文摘A Fe-containing mesoporous silica has been synthesized at room temperature using alkylamine as templating surfactant; XRD, IR, ESR and Si-29 MAS NMR spectra provided evidence of the presence of framework and non-framework iron(III) in Fe-HMS material.
基金funded by Jiangsu Shuang Chuang Tuan Dui program (JSSCTD202147)Jiangsu Shuang Chuang Ren Cai program (JSSCRC2021541)+1 种基金Young Elite Scientists Sponsorship Program by CAST (2022QNRC001)the Initiation Funds of Yangzhou University for Distinguished Scientists
文摘Background Our previous studies demonstrated that divalent organic iron(Fe)proteinate sources with higher complexation or chelation strengths as expressed by the greater quotient of formation(Qf)values displayed higher Fe bioavailabilities for broilers.Sodium iron ethylenediaminetetraacetate(NaFeEDTA)is a trivalent organic Fe source with the strongest chelating ligand EDTA.However,the bioavailability of Fe when administered as NaFeEDTA in broilers and other agricultural animals remains untested.Herein,the chemical characteristics of 12 NaFeEDTA products were determined.Of these,one feed grade NaFeEDTA(Qf=2.07×10^(8)),one food grade NaFeEDTA(Qf=3.31×10^(8)),and one Fe proteinate with an extremely strong chelation strength(Fe-Prot ES,Qf value=8,590)were selected.Their bioavailabilities relative to Fe sulfate(FeSO_(4)·7H_(2)O)for broilers fed with a conventional corn-soybean meal diet were evaluated during d 1 to 21 by investigating the effects of the above Fe sources and added Fe levels on the growth performance,hematological indices,Fe contents,activities and gene expressions of Fe-containing enzymes in various tissues of broilers.Results NaFeEDTA sources varied greatly in their chemical characteristics.Plasma Fe concentration(PI),transferrin saturation(TS),liver Fe content,succinate dehydrogenase(SDH)activities in liver,heart,and kidney,catalase(CAT)activity in liver,and SDH mRNA expressions in liver and kidney increased linearly(P<0.05)with increasing levels of Fe supplementation.However,differences among Fe sources were detected(P<0.05)only for PI,liver Fe content,CAT activity in liver,SDH activities in heart and kidney,and SDH mRNA expressions in liver and kidney.Based on slope ratios from multiple linear regressions of the above indices on daily dietary analyzed Fe intake,the average bioavailabilities of Fe-Prot ES,feed grade NaFeEDTA,and food grade NaFeEDTA relative to the inorganic FeSO_(4)·7H_(2)O(100%)for broilers were 139%,155%,and 166%,respectively.Conclusions The bioavailabilities of organic Fe sources relative to FeSO_(4)·7H_(2)O were closely related to their Qf values,and NaFeEDTA sources with higher Qf values showed higher Fe bioavailabilities for broilers fed with a conventional corn-soybean meal diet.
基金supported by the Scientific Research Project (No.17ZB0484)of Sichuan Provincial Department of EducationScientific Research Project (No.2021ZKQN004)of Southwest Medical University+1 种基金National Natural Science Foundation of China (No.41805095)Sichuan Science and Technology Program (No.2019YFS0476)。
文摘Single-particle aerosol mass spectrometry was used to study the characteristics of Fecontaining particles during winter in Chengdu,southwest China.The mass concentrations of PM_(2.5)and PM_(10)during the study period were 64±38 and 89±49μg/m~3,respectively,and NO_(2)and particulate matter were high compared with most other regions of China.The Fecontaining particles were divided into seven categories with different mass spectra,sources and aging characteristics.The highest contribution was from Fe mixed with carbonaceous components(Fe-C,23.1%)particles.Fe was more mixed with sulfate than nitrate and therefore the contribution of Fe mixed with sulfate(Fe-S,20.7%)particles was higher than that of Fe mixed with nitrate(Fe-N,12.5%)particles.The contributions from Fe-containing particles related to primary combustion were high in the small particle size range,whereas aged Fecontaining particles and dust-related particles were mostly found in the coarse particle size range.The air masses mainly originated from the west and east of Chengdu,and the corresponding PM_(2.5)concentrations were 79±36 and 55±36μg/m~3,respectively.The west and east air masses showed stronger contributions of Fe-containing particles related to biomass burning(Fe-B)and fossil fuel combustion(Fe-C and Fe-S)particles,respectively.The southwest area contributed the most Fe-containing particles.Future assessments of the effects of Fe-containing particles during heavy pollution period should pay more attention to Fe-C and Fe-S particles.Emission-reduction of Fe-containing particles should consider both local emissions and short-distance transmission from the surrounding areas.
基金financially supported by the National Key Research and Development Program of China (No.2021YFA0718900)the National Natural Science Foundation of China (No.62074014)the Xiaomi Scholar project。
文摘Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.
基金the National Natural Science Foundation of China(Grant No.52272070)National Science and Technology Major Project(Grant No.J2022-VI-0009-0040).
文摘Environmental sediments mainly consisting of CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS)corrosion are a serious threat to thermal barrier coatings(TBCs),in which Fe element is usually ignored.Gd_(2)Zr_(2)O_(7)TBCs are famous for their excellent CMAS resistance.In this study,the characteristics of Fe-containing environmental sediments(CMAS-Fe)and their corrosiveness to Gd_(2)Zr_(2)O_(7)coatings were investigated.Four types of CMAS-Fe glass with different Fe contents were fabricated.Their melting points were measured to be 1322–1344℃,and the high-temperature viscosity showed a decreasing trend with increasing Fe contents.The corrosion behavior of four types of CMAS-Fe to Gd_(2)Zr_(2)O_(7)coatings at 1350℃was investigated.At the initial corrosion stage(0.1 h),anorthite was precipitated in CMAS-Fe with a high Ca:Si ratio,while Fe-garnet was formed in the melt with the highest Fe content.Prolonging the corrosion time resulted in the formation of a reaction layer,which exhibited an interpenetrating network composed of Gd-oxyapatite,ZrO_(2),and residual CMAS-Fe.Some spinel was precipitated within the reaction layer.After 1 h or even longer time,the reaction layers tended to be stable and compact,which had comparable hardness and fracture toughness to those of Gd_(2)Zr_(2)O_(7)coatings.Under the cyclic CMAS-Fe attack,the residual CMAS-Fe in the interpenetrating network provided a pathway for the redeposited CMAS-Fe infiltration,resulting in the continuous growth of the reaction layer.As a result,the Gd_(2)Zr_(2)O_(7)coatings had a large consumption in the thickness,degrading the coating performance.Therefore,the Gd_(2)Zr_(2)O_(7)coatings exhibit unsatisfactory corrosion resistance to CMAS-Fe attack.
基金the General Program of the National Natural Science Foundation of China(Nos.51974064,52174239)the National Key R&D Program of China(No.2021YFC2902400)the Outstanding Postdoctoral Program of Jiangsu Province,China(No.2022ZB521).
文摘To achieve efficient flotation separation of brucite and calcite,flotation separation experiments were conducted on two minerals using dodecylamine(DDA)as the collector and potassium dihydrogen phosphate(PDP)as the regulator.The action mechanism of DDA and PDP was explored through contact angle measurement,zeta potential detection,solution chemistry calculation,FTIR analysis,and XPS detection.The flotation results showed that when DDA dosage was 35 mg/L and PDP dosage was 40 mg/L,the maximum floating difference between brucite and calcite was 79.81%,and the selectivity separation index was 6.46.The detection analysis showed that the main dissolved component HPO_(4)^(2−)of PDP is selectively strongly adsorbed on the Ca site on the surface of calcite,promoting the adsorption of the main dissolved component RNH_(3)^(+)of DDA on calcite surface,while brucite is basically not affected by PDP.Therefore,PDP is an effective regulator for the reverse flotation separation of brucite and calcite in DDA system.
