稀土元素钐(Samarium,Sm)及其合金在永磁材料领域应用广泛,但其高昂的提取成本与繁琐的制备工艺严重制约发展,亟需开发新型制备方法。本研究旨在阐明Sm_(2)O_(3)、ZnO及Sm_(2)O_(3)-ZnO复合氧化物在CaCl_(2)-NaCl熔盐中的电化学行为,为...稀土元素钐(Samarium,Sm)及其合金在永磁材料领域应用广泛,但其高昂的提取成本与繁琐的制备工艺严重制约发展,亟需开发新型制备方法。本研究旨在阐明Sm_(2)O_(3)、ZnO及Sm_(2)O_(3)-ZnO复合氧化物在CaCl_(2)-NaCl熔盐中的电化学行为,为制备Sm-Zn合金提供理论依据。本文采用熔盐电脱氧法,在CaCl_(2)-NaCl熔盐体系中构建三电极系统,通过循环伏安法(Cyclic Voltammetry,CV)和方波伏安法(Square Wave Voltammetry,SWV)对Sm_(2)O_(3)、ZnO及Sm_(2)O_(3)-ZnO三种金属氧化物的电化学行为进行研究分析。研究结果表明:Sm_(2)O_(3)还原为金属Sm的还原电位约为-1.80 V vs.Ag/Ag^(+),直接电脱氧效率较低;ZnO转化为金属Zn的还原电位约为-0.75 V vs.Ag/Ag^(+);Sm_(2)O_(3)-ZnO混合物在-1.13 V vs.Ag/Ag^(+)左右被还原为SmZn12,在约-1.56 V vs.Ag/Ag^(+)处被还原形成Sm_(2)Zn_(17)合金。不同电解条件下的产物分析结果显示,相比-1.70 V vs.Ag/Ag^(+),在-2.30 V vs.Ag/Ag^(+)、923 K条件下对Sm_(2)O_(3)-ZnO进行20 h恒电位电解时Sm_(2)O_(3)-ZnO能完全转化为SmZn12和Sm_(2)Zn_(17)合金。本研究为稀土金属氧化物熔盐电解制备稀土金属及其合金提供了重要的电化学机制信息与工艺优化路径选择。展开更多
Numerical thermodynamic models are proposed for the quaternary fluid system H_(2)O-CO_(2)-NaCl-CaCl_(2)and its ternary subsystems H_(2)O-NaCl-CaCl_(2),H_(2)O-CO_(2)-NaCl,and H_(2)O-CO_(2)-CaCl_(2).The models are valid...Numerical thermodynamic models are proposed for the quaternary fluid system H_(2)O-CO_(2)-NaCl-CaCl_(2)and its ternary subsystems H_(2)O-NaCl-CaCl_(2),H_(2)O-CO_(2)-NaCl,and H_(2)O-CO_(2)-CaCl_(2).The models are valid for temperatures from 150℃to 350℃,pressures from 0.2 to 1.4 kbar,and for arbitrary concentrations of salts.The latter feature is inherited from the earlier developed models of binary systems H_(2)O-NaCl and H_(2)O-CaCl_(2).All the models are formulated in terms of the Gibbs free energy.The entropy term in the equation for the Gibbs free energy of mixing is introduced in a general form,based on the number of different ways of arranging particles in the system that lead to the same total energy.The parameters of the energy terms corresponding to the interactions of particles in binary and ternary subsystems are obtained by fitting published experimental data.The concentrations of salts in the gas phase are simulated based on the salt evaporation free energy.Our model,also available as a computer code,makes it possible to predict the physicochemical properties of fluids involved in hydrothermal processes in the upper crust:the phase state of the system(homogeneous or two-phase fluid),activities of the components,densities,and compositions of the(coexisting)fluid phases.The model offers a numerical tool for analyzing fluid inclusion data and better understanding of metamorphic and metasomatic processes in the upper crust.Fluids at studied P-T conditions play a decisive role in the formation of hydrothermal ore deposits,including most of the world's gold deposits.展开更多
In Saharan climates,greenhouses face extreme diurnal temperature fluctuations that generate thermal stress,reduce crop productivity,and hinder sustainable agricultural practices.Passive thermal storage using Phase Cha...In Saharan climates,greenhouses face extreme diurnal temperature fluctuations that generate thermal stress,reduce crop productivity,and hinder sustainable agricultural practices.Passive thermal storage using Phase Change Materials(PCM)is a promising solution to stabilize microclimatic conditions.This study aims to evaluate experimentally and numerically the effectiveness of PCM integration for moderating greenhouse temperature fluctuations under Saharan climatic conditions.Two identical greenhouse prototypes were constructed in Ghardaia,Algeria:a reference greenhouse and a PCM-integrated greenhouse using calcium chloride hexahydrate(CaCl_(2)⋅6H_(2)O).Thermal performance was assessed during a five-day experimental period(7–11May 2025)under severe ambient conditions.To complement this,a Nonlinear Auto-Regressive with eXogenous inputs(NARX)neural network model was developed and trained using a larger dataset(7–25 May 2025)to predict greenhouse thermal dynamics.The PCM greenhouse reduced peak daytime air temperature by an average of 8.14℃and decreased the diurnal temperature amplitude by 53.6%compared to the reference greenhouse.The NARX model achieved high predictive accuracy(R^(2)=0.990,RMSE=0.425℃,MAE=0.223℃,MBE=0.008℃),capturing both sensible and latent heat transfer mechanisms,including PCM melting and solidification.The combined experimental and predictive modeling results confirm the potential of PCM integration as an effective passive thermal regulation strategy for greenhouses in arid regions.This approach enhances microclimatic stability,improves energy efficiency,and supports the sustainability of protected agriculture under extreme climatic conditions.展开更多
(以酸枣(Ziziphus acidojujuba C.Y.Cheng et M.J.Liu)水培实生幼苗为试材,研究了CaCl_(2)对NaCl胁迫下其根、茎、叶中抗坏血酸—谷胱甘肽循环(AsA-GSH)的影响。结果表明:与对照(日本园试配方营养液)相比,NaCl处理下根和叶中AsA含量升高...(以酸枣(Ziziphus acidojujuba C.Y.Cheng et M.J.Liu)水培实生幼苗为试材,研究了CaCl_(2)对NaCl胁迫下其根、茎、叶中抗坏血酸—谷胱甘肽循环(AsA-GSH)的影响。结果表明:与对照(日本园试配方营养液)相比,NaCl处理下根和叶中AsA含量升高,MDHAR活性升高,APX活性下降;根、茎、叶中GSH含量升高。NaCl+CaCl_(2)处理与NaC处理相比,根和茎中AsA含量进一步升高,叶中AsA含量下降,叶中APX下降,根中MDHAR活性进一步升高,茎和叶中DHAR活性升高;根和叶中GSH含量下降。外源CaCl_(2)可能通过提高酸枣实生苗根、茎和叶中AsA再生关键酶MDHAR和DHAR活性,促进根和茎中AsA的再生与生物合成,从而提高根、茎清除过量H_(2)O_(2)的能力,缓解NaCl胁迫对酸枣幼苗根和茎部的伤害。)展开更多
文摘稀土元素钐(Samarium,Sm)及其合金在永磁材料领域应用广泛,但其高昂的提取成本与繁琐的制备工艺严重制约发展,亟需开发新型制备方法。本研究旨在阐明Sm_(2)O_(3)、ZnO及Sm_(2)O_(3)-ZnO复合氧化物在CaCl_(2)-NaCl熔盐中的电化学行为,为制备Sm-Zn合金提供理论依据。本文采用熔盐电脱氧法,在CaCl_(2)-NaCl熔盐体系中构建三电极系统,通过循环伏安法(Cyclic Voltammetry,CV)和方波伏安法(Square Wave Voltammetry,SWV)对Sm_(2)O_(3)、ZnO及Sm_(2)O_(3)-ZnO三种金属氧化物的电化学行为进行研究分析。研究结果表明:Sm_(2)O_(3)还原为金属Sm的还原电位约为-1.80 V vs.Ag/Ag^(+),直接电脱氧效率较低;ZnO转化为金属Zn的还原电位约为-0.75 V vs.Ag/Ag^(+);Sm_(2)O_(3)-ZnO混合物在-1.13 V vs.Ag/Ag^(+)左右被还原为SmZn12,在约-1.56 V vs.Ag/Ag^(+)处被还原形成Sm_(2)Zn_(17)合金。不同电解条件下的产物分析结果显示,相比-1.70 V vs.Ag/Ag^(+),在-2.30 V vs.Ag/Ag^(+)、923 K条件下对Sm_(2)O_(3)-ZnO进行20 h恒电位电解时Sm_(2)O_(3)-ZnO能完全转化为SmZn12和Sm_(2)Zn_(17)合金。本研究为稀土金属氧化物熔盐电解制备稀土金属及其合金提供了重要的电化学机制信息与工艺优化路径选择。
基金the Research Program of the IPGG RAS FMUW-2021-0002.
文摘Numerical thermodynamic models are proposed for the quaternary fluid system H_(2)O-CO_(2)-NaCl-CaCl_(2)and its ternary subsystems H_(2)O-NaCl-CaCl_(2),H_(2)O-CO_(2)-NaCl,and H_(2)O-CO_(2)-CaCl_(2).The models are valid for temperatures from 150℃to 350℃,pressures from 0.2 to 1.4 kbar,and for arbitrary concentrations of salts.The latter feature is inherited from the earlier developed models of binary systems H_(2)O-NaCl and H_(2)O-CaCl_(2).All the models are formulated in terms of the Gibbs free energy.The entropy term in the equation for the Gibbs free energy of mixing is introduced in a general form,based on the number of different ways of arranging particles in the system that lead to the same total energy.The parameters of the energy terms corresponding to the interactions of particles in binary and ternary subsystems are obtained by fitting published experimental data.The concentrations of salts in the gas phase are simulated based on the salt evaporation free energy.Our model,also available as a computer code,makes it possible to predict the physicochemical properties of fluids involved in hydrothermal processes in the upper crust:the phase state of the system(homogeneous or two-phase fluid),activities of the components,densities,and compositions of the(coexisting)fluid phases.The model offers a numerical tool for analyzing fluid inclusion data and better understanding of metamorphic and metasomatic processes in the upper crust.Fluids at studied P-T conditions play a decisive role in the formation of hydrothermal ore deposits,including most of the world's gold deposits.
文摘In Saharan climates,greenhouses face extreme diurnal temperature fluctuations that generate thermal stress,reduce crop productivity,and hinder sustainable agricultural practices.Passive thermal storage using Phase Change Materials(PCM)is a promising solution to stabilize microclimatic conditions.This study aims to evaluate experimentally and numerically the effectiveness of PCM integration for moderating greenhouse temperature fluctuations under Saharan climatic conditions.Two identical greenhouse prototypes were constructed in Ghardaia,Algeria:a reference greenhouse and a PCM-integrated greenhouse using calcium chloride hexahydrate(CaCl_(2)⋅6H_(2)O).Thermal performance was assessed during a five-day experimental period(7–11May 2025)under severe ambient conditions.To complement this,a Nonlinear Auto-Regressive with eXogenous inputs(NARX)neural network model was developed and trained using a larger dataset(7–25 May 2025)to predict greenhouse thermal dynamics.The PCM greenhouse reduced peak daytime air temperature by an average of 8.14℃and decreased the diurnal temperature amplitude by 53.6%compared to the reference greenhouse.The NARX model achieved high predictive accuracy(R^(2)=0.990,RMSE=0.425℃,MAE=0.223℃,MBE=0.008℃),capturing both sensible and latent heat transfer mechanisms,including PCM melting and solidification.The combined experimental and predictive modeling results confirm the potential of PCM integration as an effective passive thermal regulation strategy for greenhouses in arid regions.This approach enhances microclimatic stability,improves energy efficiency,and supports the sustainability of protected agriculture under extreme climatic conditions.
文摘(以酸枣(Ziziphus acidojujuba C.Y.Cheng et M.J.Liu)水培实生幼苗为试材,研究了CaCl_(2)对NaCl胁迫下其根、茎、叶中抗坏血酸—谷胱甘肽循环(AsA-GSH)的影响。结果表明:与对照(日本园试配方营养液)相比,NaCl处理下根和叶中AsA含量升高,MDHAR活性升高,APX活性下降;根、茎、叶中GSH含量升高。NaCl+CaCl_(2)处理与NaC处理相比,根和茎中AsA含量进一步升高,叶中AsA含量下降,叶中APX下降,根中MDHAR活性进一步升高,茎和叶中DHAR活性升高;根和叶中GSH含量下降。外源CaCl_(2)可能通过提高酸枣实生苗根、茎和叶中AsA再生关键酶MDHAR和DHAR活性,促进根和茎中AsA的再生与生物合成,从而提高根、茎清除过量H_(2)O_(2)的能力,缓解NaCl胁迫对酸枣幼苗根和茎部的伤害。)
