Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcina...Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcination of kaolinitic clays has been investigated as a sustainable alternative.This technique involves the rapid heating of clays,enabling their use as supplementary cementitious materials.The primary objective of this study was to modify the color of calcined clay in various atmospheres(oxidizing,inert,and reducing)to achieve a grayish tone similar to commercial cement while preserving its reactive properties.The experimental procedure employed a tubular reactor with precise control of gas flows(atmospheric air,nitrogen,and a carbon monoxide–nitrogen mixture).Physicochemical characterization of the raw clay was conducted before calcination,with analyses repeated on the calcined clays following experimentation.Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue,attributed to the oxidation of iron in hematite.The Clay exhibited a pinkish tone in an inert atmosphere,while calcination in a reducing atmosphere yielded the desired grayish color.Regarding pozzolanic activity,clays calcined in oxidizing and inert atmospheres displayed robust strength,ranging from 82%to 87%.Calcination in a reducing atmosphere resulted in slightly lower strength,around 74%,likely due to the clay’s chemical composition and the calcination process,which affects compound formation and material reactivity.展开更多
The present work aims to investigate the effect of heating temperature(400,600 and 800°C)and inoculating elements(Ca,Ca-Ba,Ca-RE)on oxidation behavior of ductile irons containing 5.25%Si and 4.8%Si-2.3%Mo in dry ...The present work aims to investigate the effect of heating temperature(400,600 and 800°C)and inoculating elements(Ca,Ca-Ba,Ca-RE)on oxidation behavior of ductile irons containing 5.25%Si and 4.8%Si-2.3%Mo in dry air and combustion gas containing water vapour(natural gas burning).The oxidation is influenced by the gas atmosphere type,the iron alloying system,and the inoculating elements depending on the heating temperature.The weight gain increases from 0.001%-0.1%(400°C)to 0.05%-0.70%(600°C)and up to 0.10%-2.15%(800°C).No particular effects of the considered influencing factors are found when heating at 400°C,while at 600°C,mainly the oxidation gas atmosphere type shows a visible influence.At the highest heating temperature of 800°C,a limited increase of the weight gain is found for dry air atmosphere(up to 0.25%),but it drastically increases for combustion atmospheres(0.65%-2.15%).The water vapour presence in the combustion atmosphere is an important oxidising factor at 600-800°C.The alloying system appears to influence the oxidation behavior mainly at a heating temperature of 800°C in the combustion atmosphere,as evidenced by the lower weight gain in 5.25%silicon cast iron.Positive effects of inoculating elements increase with the heating temperature,with Ca and Ba-FeSi inoculation generally showing better performance.Irons inoculated with CaRE-FeSi exhibit a higher degree of oxidation.These results are in good relationship with the previous reported data:Ca-Ba-inoculation system appears to be better than simple Ca for improving the graphite parameters,while RE-bearing inoculant negatively affects the compactness degree of graphite particles in high-Si ductile irons.As the lower compactness degree is typical for graphite nodules in high-Si ductile irons,which negatively affects the oxidation resistance,it is necessary to employ specific metallurgical treatments to improve nodule quality.Inoculation,in particular,is a potential method to achieve this improvement.展开更多
In an era of scene-based consumption,the essence of operating a bookstore lies in accepting and enabling the bookstore to play its role as a cultural medium for browsing and appreciating books,which in turn fosters th...In an era of scene-based consumption,the essence of operating a bookstore lies in accepting and enabling the bookstore to play its role as a cultural medium for browsing and appreciating books,which in turn fosters the development of a distinctive bookstore culture.This new type of consumption context has led to an evolution in the book-reading culture in physical bookstores that is characterized by a shift from a paradigm of passive reading to one where the emphasis is on interactive viewing.This transition has laid the foundation for the creation of cultural atmospheres in bookstores,and it highlights the visual interactions that now exist between readers and books as well as with other related cultural industries.The dominant and fundamental logic behind this process is symbiosis,experience,aesthetics,immersion,and creativity.However,when a form of culture that focuses on consumption-oriented browsing begins to overshadow knowledge acquisition during the process of book reading,the cultural essence of bookstores is likely to be diminished.Therefore,the cultural essence within the scene-based consumption context should be enhanced by creating innovative viewing activities that showcase the cultural and emotional implications inherent in the scene itself,and thus help to align the identity of the bookstore with its in-situ cultural space.展开更多
The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray spectroscopy （EDS...The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction（XRD）. The effects of brazing atmospheres on the as-brazed NiCr brazing alloy composite structures and interracial microstructure are studied between diamond grits and brazing alloy. Results show that： （1） There are different composite structures of as-brazed NiCr brazing alloy under different oxygen partial pressures in vacuum and argon gas. B203 exists on the surface of the brazed samples under argon gas furnace brazing. It indicates that oxygen plays an important role in the resultants of as-brazed NiCr brazing alloy during the brazing process. （2） There are different interfacial microstructures in different brazing atmospheres, but the main reaction product is chromium carbides. The chromium carbides in argon gas furnace brazing grow in a disordered form, but those in vacuum furnace brazing grow radiated. And the scale of grains in argon gas is smaller than those in vacuum.展开更多
BaCe0.45Zr0.45M0.1O3-δ （M=Y, In） and BaCe0.9Y0.1O3-δ were prepared through the conventional solid state reaction route. The chemical stability was investigated in hydrogen, carbon dioxide, and boiling water. Cryst...BaCe0.45Zr0.45M0.1O3-δ （M=Y, In） and BaCe0.9Y0.1O3-δ were prepared through the conventional solid state reaction route. The chemical stability was investigated in hydrogen, carbon dioxide, and boiling water. Crystalline phase and microsa-ucture of the proton conductor before and after stability test were measured with X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. The results showed that all materials were quite stable in H2 atmosphere. In CO2 atmosphere, BaCe0.45Zr0.45M0.1O3-δ（M=Y, In） were relatively stable, while Bafe0.9Y0.1O3-δ decomposed. In boiling water, BaCe0.9Y0.1O3-δ was quickly decomposed into Ba（OH）2 and corresponding oxide. BaCe0.45Zr0.45M0.1O3-δ slightly reacted with boiling water and some amorphous phases were formed. However, BaCe0.45Zr0.45In0.1O3-δ was observed to exhibit better stability than BaCe0.45Zr0.45Y0.1O3-δ in water. The experimental results were interpreted in terms of thermodynamic data and tolerance factor.展开更多
So far,it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation.Herein,the influence of the different atmospheres pretreatment(oxidative and reductive)on gold ...So far,it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation.Herein,the influence of the different atmospheres pretreatment(oxidative and reductive)on gold state of Au/La-CeOx(1 wt%gold loading)catalyst during CO oxidation was studied.The changes of Au species were monitored by combined in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS)and X-ray photoelectron spectroscopy(XPS).For the sample pretreated with oxidative atmosphere,the data show that the initial Au^(3+)is transformed to Au^(δ+)(0<δ<1)during CO oxidation,which is a key step to lead to higher reactivity.For the sample after reductive atmosphere pretreatment,Au^(δ+)is mixed with a small amount of Au^(0)which can be converted to Au^(δ+)with the increase of temperature in reaction.Meanwhile,the sample always maintains high activity during the reaction.Therefore,the Au®+obtained by reductive pretreatment is more active than the Au^(3+)obtained by oxidative treatment in catalyzing CO oxidation.展开更多
Regenerated MgO-CaO brick samples containing 80wt%, 70wt%, and 60wt% MgO were prepared using spent MgO-CaO bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K for 2 ...Regenerated MgO-CaO brick samples containing 80wt%, 70wt%, and 60wt% MgO were prepared using spent MgO-CaO bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K for 2 h under an air atmosphere and under an isolating system. The microstructure, mechanical properties at room temperature, and hydration resistance of the regenerated samples were measured and compared. The results indicated that the isolating sintering generated a strongly reducing atmosphere as a result of the incomplete combustion of paraffin, and the partial oxygen pressure was approximately 6.68 × 10^-7 Pa. The properties of the regenerated bricks sintered under air conditions were all higher than those of the bricks sintered under a reducing atmosphere. The deterioration of the bricks was a result of MgO reduction and a decrease in the amount of liquid phase formed during sintering under a reducing atmosphere.展开更多
A new way to measure the departure from thermodynamic equilibrium is proposed based on the departure factor which evaluates the deviation from a Boltzmann level distribution, used by Short and Hauschildt （2005） and ...A new way to measure the departure from thermodynamic equilibrium is proposed based on the departure factor which evaluates the deviation from a Boltzmann level distribution, used by Short and Hauschildt （2005） and others. The way is based on an explicit relationship describing the departure factor as a function of line to continuum source, dynamic temperature and line photon frequency, under three assumptions that the scattering can be neglected, the background continuum can be treated as a Planck function, and finally the complete redistribution can be true. It has the advantage that the departure can be very conveniently evaluated from the spectral analysis with only the radiative transfer involved. Some physical insights are recovered for some extreme cases. Some example calculations of the departure are presented for the quiet Sun, faint solar flare and strong solar flare for the generally used solar chromospheric lines： Hα, Hβ, CaII H, K and triplet. It is revealed that in the case of solar flares, the departure is less than thermodynamic equilibrium along the larger depth range than in the quiet sun due to chromospheric condensation. It becomes hard to distinguish the departures for the different lines of the same atom or ion. It is expected that this investigation can be constructive for studying stellar atmospheres in cases where the three assumptions are close to reality.展开更多
Raney-Copper(R-Cu)catalyst was prepared and its sintering behaviour in atmospheres at teperature 300℃-600℃ was detected by methods of SSA,PSD,XRD and SEM.It was found that sintering of R-Cu started from much lower t...Raney-Copper(R-Cu)catalyst was prepared and its sintering behaviour in atmospheres at teperature 300℃-600℃ was detected by methods of SSA,PSD,XRD and SEM.It was found that sintering of R-Cu started from much lower temperature than the melting point of copper.Changes both on the surface and in the body phase were discovered.There is a rule in the extent of sintering for R-Cu in different atmospheres which is related to the adsorption of the particular gases molecules on the surface of the catalyst.Dynamical equations of the surface decrease is established and the mechanism of sintering is discussed.Calculations of quantum mechanics give the similar results.展开更多
The effects of atmospheres and precursors on MnOx/TiO2 catalysts were studied, which were prepared by the impregnation method and tested for their NOx conversion activity in ammonia selective catalytic reduction （NH3...The effects of atmospheres and precursors on MnOx/TiO2 catalysts were studied, which were prepared by the impregnation method and tested for their NOx conversion activity in ammonia selective catalytic reduction （NH3-SCR） reactions. Results showed that the manganese carbonate （MC） precursor caused mainly Mn2O3, while the manganese nitrate （MN） precursor resulted primarily in MnO2 and the manganese sulfate （MS） precursor was unchanged. The manganese acetate （MA） precursor leaded obtaining a mixture of Mn2O3 and Mn304. NOn conversion decreased in the following order： MA/TiO2 〉 MC/TiO2 〉 MN/TiO2 〉 MS/TiO2 〉 P25, with a calcination temperature of 773 K in air. Catalysts that were prepared by MA and calcined in oxygen performed strong interaction between Ti and Mn, while MnTiO3 was observed. Compared to the catalysts calcined in nitrogen, those calcined in oxygen had larger diameter and smaller surface area and pore. Catalysts that were prepared by MA and calcined in nitrogen tended to gain higher denitration rates than those in air, since they could be prepared with significant specific surface areas. NO., conversion decreased with calcination atmospheres： Nitrogen〉 Air〉 Oxygen. Meanwhile, amorphous Mn2O3 turned into crystalline Mn2O3, when the temperatures increased from 673 to 873 K.展开更多
In this study,water-dispersible graphitic carbon nitride(g-C_(3)N_(4))photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C_(3)N_(4) that was polymerized thermally in different...In this study,water-dispersible graphitic carbon nitride(g-C_(3)N_(4))photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C_(3)N_(4) that was polymerized thermally in different calcination atmospheres such as air,CO_(2),and N_(2).The different calcination atmospheres directly influenced the physicochemical and optical properties of both bulk and water-dispersible g-C_(3)N_(4),changing the photocatalytic degradation behavior of methylene blue(MB)and tetracycline hydrochloride(TCHCl)for water-dispersible g-C_(3)N_(4).The bubble-burst process in the thermal polymerization of thiourea produced defective edges containing C=O groups that preferred substituting the C-NHx groups over bulk g-C_(3)N_(4).In the oxygen-free N_(2) atmosphere among the different calcination atmospheres,more C=O functional groups were generated on the defective edges of bulk g-C_(3)N_(4),resulting in the highest N vacancy of the tri-s-triazine structure.During the successive chemical oxidation,S-or O-containing functional groups were introduced onto water-dispersible g-C_(3)N_(4).The water-dispersible g-C_(3)N_(4) photocatalyst from the oxygen-free N_(2) atmosphere(NTw)contained the most O-and S-functional groups on the g-C_(3)N_(4) surface.Consequently,NTw exhibited the highest photocatalytic activity in the MB and TC-HCl photodegradation because of its slowest recombination process,which was ascribed to the unique surface properties of NTw such as abundant functional groups on the defective edges and N-deficient property.展开更多
The microstructure of coke has an important influence on its thermal properties.The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation.The results showed that the isotr...The microstructure of coke has an important influence on its thermal properties.The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation.The results showed that the isotropic components had a more vigorous reaction than the anisotropic components,and the solution loss reaction of the fine-grained mosaic structure was faster than that of the coarse-grained mosaic structure under the CO2 and H2O atmospheres.The coarse-grained mosaic structure and the flowing structure had a relatively higher anti-erosion ability in the CO2 atmosphere than in the H2O atmosphere,and there was no distinct difference in the solution loss of the isotropic structure under the CO2 and H2O atmospheres.The electron probe microanalysis showed that the Al-Si-Fe compounds in the carbon matrix had positive influence on the solution loss reaction of the anisotropic structure.The iron compounds were able to destroy the pore walls of coke and accelerate the solution loss rate of coke.展开更多
The catalytic activity and durability of Rh/ZrO2 catalyst were investigated compared with Rh/Al2O3 catalyst under diverse aging atmospheres, including lean, rich and lean–rich cyclic aging atmospheres, to simulate th...The catalytic activity and durability of Rh/ZrO2 catalyst were investigated compared with Rh/Al2O3 catalyst under diverse aging atmospheres, including lean, rich and lean–rich cyclic aging atmospheres, to simulate the real working conditions of three-way catalyst.Oxidation states and microstructures of rhodium species were investigated to correlate with the catalytic performance of the catalysts. The catalytic performance and durability of the Rh catalyst under diverse aging atmospheres were drastically enhanced by ZrO2 support. ZrO2 support was confirmed to be able to effectively inhibit rhodium sintering even under diverse aging conditions. It can also successfully keep Rh species in an active low-valence state on the surface of the catalyst. The superiority of ZrO2 support compared to Al2O3 was verified by the Rh-based monolith catalyst.展开更多
The changes in physiological characteristics, quality and storability of the sweet cherry (Pru-mus avium L. cv. Hongdeng) stored in controlled atmospheres (CA), in modified atmosphere packages (MAP) and in air (CK) we...The changes in physiological characteristics, quality and storability of the sweet cherry (Pru-mus avium L. cv. Hongdeng) stored in controlled atmospheres (CA), in modified atmosphere packages (MAP) and in air (CK) were investigated in this paper. The results showed that CA and MAP treatments significantly inhibited fruit rot and flesh browning, kept firmness and fruit color, reduced ethylene and ethanol content in pulp, slowed down the increase of polyphenol oxidase (PPO) and peroxidase (POD) activity and malondialdehyde (MDA) content in comparison with CK. Meanwhile, CA treatments showed a better benefit of reducing ethylene and ethanol contents, inhibiting PPO and POD activities, declining rot rate and browning index compared to MAP. The fruit could be stored in CA conditions for 60 days without any off-flavor. The sweet cherries kept in CA with 5% O2 + 10% CO2 showed a better storability than that in CA with 5% O2 + 5% CO2.展开更多
Ru-based catalysts modified in different atmospheres by plasma technology were prepared to catalyze the acetylene hydrochlorination reaction.The(Ru/AC)-N_(2)(AC = activated carbon)catalyst yielded by the plasma modifi...Ru-based catalysts modified in different atmospheres by plasma technology were prepared to catalyze the acetylene hydrochlorination reaction.The(Ru/AC)-N_(2)(AC = activated carbon)catalyst yielded by the plasma modification of Ru/AC catalyst in N2 atmosphere exhibits the best catalytic performance with a stable C_(2)H_(2) conversion of 87.2%;a relative increase of 27.1%in C2H2 conversion was achieved compared with that of the untreated Ru/AC catalyst.The results of the analysis revealed that the modification produced a mutual effect between the generated function groups on carrier AC and the active components, which can disperse and yield more active species in the fresh catalysts.These are benefits of enhancing the activity of the catalysts.Moreover, the modification can restrain coke formation and inhibit the loss of active species in the reaction, as well as strengthen the adsorption ability of reactants on the catalysts.These are benefits of improving the catalysts’ performance.展开更多
The quality of Yi＇an gas coal before and after low temperature upgrading under either a N2 or H2 atmosphere was examined by thermogravimetric and infrared analyses. The effect of upgrading on the prepared coke qualit...The quality of Yi＇an gas coal before and after low temperature upgrading under either a N2 or H2 atmosphere was examined by thermogravimetric and infrared analyses. The effect of upgrading on the prepared coke quality was analyzed. The results show that the carboxyl and phenolic hydroxyls in the coal molecular structure are removed after upgrading by low temperature pyrolysis under either N2 or Hz atmospheres. This improves coal caking properties to a certain extent. The upgrading effect under a Hz atmosphere is remarkably better than the effect observed after upgrading under N2. Compared to coke obtained from raw coal, the compressiveand micro-strength of the cokes obtained from upgraded coal are greatly improved. The effect on coke reactivity with CO2 is not significant. The best upgrading temperature for Yi＇an gas coal under either a N2 or H2 atmosphere is 250 or 275 ℃ respectively.展开更多
The line formation process in stellar magnetized atmospheres is studied by observing the wavelength- dependence of Stokes contribution functions. The influence of magnetic field on the escape line photon distribution...The line formation process in stellar magnetized atmospheres is studied by observing the wavelength- dependence of Stokes contribution functions. The influence of magnetic field on the escape line photon distribution and line absorption is obtained by comparing with the null magnetic field case. Two models airs adopted. One assumes limited distributions of both the line absorption and magnetic field where a hypothetical magneto-sensitive line is formed. The other is a model atmosphere of sunspot umbra in which MgI 5172.7 forms. It is found that the magnetic field influences the formation region of Stokes I at wavelengths sufficient close to the Zeeman splitting points ±△ H. The formation regions at wavelengths far away from the Zeeman splitting points generally show a non-magnetic behaviour. Further, if the line core is split by the Zeeman effect, the line formation core introduced in the previous paper disappears. On the other hand, Stokes Q, U, V at each wavelength within the line form in the same layers where both the line absorption and magnetic field are present in the models accepted for the lines used. When the line absorption and magnetic field ubiquitously exist, the formation regions of the T peaks or valleys of Stokes Q, U and those of σ of Stokes V generally cover the widest depth range. It is pointed out that such a study is instructive in the explanation of solar polarized filtergrams. It can tell us at each observation point where the received line photons of wavelengths within the bandpass come from and where their polarization states are formed or give us the distributions of these photons as well as their polarization intensities. Thus a three-dimensional image can be constructed for a morphologic study of the observed area from serial filtergrams.展开更多
Vertical profiles of seasonally varying pressure, temperature, water vapor, and trace gases （O3, N2O, CO, CH4）, representing atmospheric conditions up to a height of 100 km over the East Asia region （30°-50...Vertical profiles of seasonally varying pressure, temperature, water vapor, and trace gases （O3, N2O, CO, CH4）, representing atmospheric conditions up to a height of 100 km over the East Asia region （30°-50°N, 110°-150°E） were constructed by using various observation data, model outputs of atmospheric thermodynamic parameters, and gaseous concentrations. Optical characteristics of the obtained East Asia reference atmospheres were compared with those from typical midlatitude summer and winter atmospheres. It was noted that, in the water vapor field, there are major differences between the two model atmospheres during the summer. The resultant impact during the summer of water vapor difference on incoming solar fluxes at the surface and emitted terrestrial fluxes at the top of the atmosphere are 14.3 W m^-2 and 6.5 W m^-2, respectively. On the other hand, the winter difference between East Asian and midlatitude atmospheres appears to be insignificant. Reference atmospheres for the spring and fall are also available. Utilizing the constructed atmospheric profiles as inputs to the radiative transfer model, it is expected that the constructed seasonally varying reference atmospheres can facilitate better descriptions of optical properties in East Asia.展开更多
Geological and astronomical observations on the‘‘lava world’’of the rocky planet,with additional theoretical interpretation of Moon’s crustal formation,bring up to the occurrence of the magma ocean and lava ponds...Geological and astronomical observations on the‘‘lava world’’of the rocky planet,with additional theoretical interpretation of Moon’s crustal formation,bring up to the occurrence of the magma ocean and lava ponds,which inherits accretion energy of rocky planetesimal and evolves with subsequent energy releases.Hemispherical or global oceans of silicate melt could be a widespread lava phase after rocky planet accretion as well as large impact and could persist on planets on orbits around other stars for various time scales.The processes of magma ocean formation and solidification change the phases,cause element segregations,and strongly affect the earliest compositional differentiation and volatile content of the terrestrial planets.They form the starting point for cooling to mildly habitable conditions and for the onset of thermally driven solid-state mantle convection.The formation and crystallization of magma oceans also influence the assembly of a core,the origin of a crust,initiation of tectonics,and formation of an atmosphere.It is inevitable to investigate the magma ocean dynamics of such an early period of Earth evolution.This review focuses on the internal dynamics of magma oceans after planetesimal accretion and planetary formation including turbulence,particle motion,and solid-state convection,which determine the associated processes of cooling,crystallization,and convection of magma ocean.Geochemical differentiation is discussed correspondingly.The thermodynamics of equilibration between a magma ocean and an overlying,outgassed atmosphere is also discussed,highlighting the need for more data on volatile solubility in silicate melts.The effect of coupling between magma ocean and solid-state mantle convection is also discussed.展开更多
Atmospheric escape is a key process controlling the long term evolution of planets. Radiative cooling competes for energy against atmospheric escape in planetary upper atmospheres. In this work, we use a population ba...Atmospheric escape is a key process controlling the long term evolution of planets. Radiative cooling competes for energy against atmospheric escape in planetary upper atmospheres. In this work, we use a population balance method and a Monte Carlo model to calculate the previously ignored emissions of metals(C, N, O and their ions) and compare them with radiative recombination of H II and Ly-α emission of H I, which are the most efficient cooling mechanisms currently recognized in the upper atmospheres of hot Jupiters.The results show that the emissions of C, N, O and their ions are strong non-linear functions of environmental parameters(temperature,density, etc.) and are likely to be efficient cooling mechanisms in the upper atmospheres of close-in exoplanets.展开更多
基金financial support for the research and for the publication costs of the articlesupported by Santa Catarina State Research Support Foundation(FAPESC)National Council for Scientific and Technological Development(CNPq no 302903/2023-2).
文摘Cement production,while essential for global infrastructure,contributes significantly to carbon dioxide emissions,accounting for approximately 7%of total emissions.To mitigate these environmental impacts,flash calcination of kaolinitic clays has been investigated as a sustainable alternative.This technique involves the rapid heating of clays,enabling their use as supplementary cementitious materials.The primary objective of this study was to modify the color of calcined clay in various atmospheres(oxidizing,inert,and reducing)to achieve a grayish tone similar to commercial cement while preserving its reactive properties.The experimental procedure employed a tubular reactor with precise control of gas flows(atmospheric air,nitrogen,and a carbon monoxide–nitrogen mixture).Physicochemical characterization of the raw clay was conducted before calcination,with analyses repeated on the calcined clays following experimentation.Results indicated that clay calcined in an oxidizing atmosphere acquired a reddish hue,attributed to the oxidation of iron in hematite.The Clay exhibited a pinkish tone in an inert atmosphere,while calcination in a reducing atmosphere yielded the desired grayish color.Regarding pozzolanic activity,clays calcined in oxidizing and inert atmospheres displayed robust strength,ranging from 82%to 87%.Calcination in a reducing atmosphere resulted in slightly lower strength,around 74%,likely due to the clay’s chemical composition and the calcination process,which affects compound formation and material reactivity.
基金supported by a grant from National Program for Research of the National Association of Technical Universities-GNAC ARUT 2023.
文摘The present work aims to investigate the effect of heating temperature(400,600 and 800°C)and inoculating elements(Ca,Ca-Ba,Ca-RE)on oxidation behavior of ductile irons containing 5.25%Si and 4.8%Si-2.3%Mo in dry air and combustion gas containing water vapour(natural gas burning).The oxidation is influenced by the gas atmosphere type,the iron alloying system,and the inoculating elements depending on the heating temperature.The weight gain increases from 0.001%-0.1%(400°C)to 0.05%-0.70%(600°C)and up to 0.10%-2.15%(800°C).No particular effects of the considered influencing factors are found when heating at 400°C,while at 600°C,mainly the oxidation gas atmosphere type shows a visible influence.At the highest heating temperature of 800°C,a limited increase of the weight gain is found for dry air atmosphere(up to 0.25%),but it drastically increases for combustion atmospheres(0.65%-2.15%).The water vapour presence in the combustion atmosphere is an important oxidising factor at 600-800°C.The alloying system appears to influence the oxidation behavior mainly at a heating temperature of 800°C in the combustion atmosphere,as evidenced by the lower weight gain in 5.25%silicon cast iron.Positive effects of inoculating elements increase with the heating temperature,with Ca and Ba-FeSi inoculation generally showing better performance.Irons inoculated with CaRE-FeSi exhibit a higher degree of oxidation.These results are in good relationship with the previous reported data:Ca-Ba-inoculation system appears to be better than simple Ca for improving the graphite parameters,while RE-bearing inoculant negatively affects the compactness degree of graphite particles in high-Si ductile irons.As the lower compactness degree is typical for graphite nodules in high-Si ductile irons,which negatively affects the oxidation resistance,it is necessary to employ specific metallurgical treatments to improve nodule quality.Inoculation,in particular,is a potential method to achieve this improvement.
基金supported by the Zhijiang Youth Special Project entitled“Cross-Cultural Examination of National Identity and Discourse Formation in Chinese Short Video Content” (Project No.:24ZJQN026Y)a philosophy and social sciences project funded by Zhejiang province。
文摘In an era of scene-based consumption,the essence of operating a bookstore lies in accepting and enabling the bookstore to play its role as a cultural medium for browsing and appreciating books,which in turn fosters the development of a distinctive bookstore culture.This new type of consumption context has led to an evolution in the book-reading culture in physical bookstores that is characterized by a shift from a paradigm of passive reading to one where the emphasis is on interactive viewing.This transition has laid the foundation for the creation of cultural atmospheres in bookstores,and it highlights the visual interactions that now exist between readers and books as well as with other related cultural industries.The dominant and fundamental logic behind this process is symbiosis,experience,aesthetics,immersion,and creativity.However,when a form of culture that focuses on consumption-oriented browsing begins to overshadow knowledge acquisition during the process of book reading,the cultural essence of bookstores is likely to be diminished.Therefore,the cultural essence within the scene-based consumption context should be enhanced by creating innovative viewing activities that showcase the cultural and emotional implications inherent in the scene itself,and thus help to align the identity of the bookstore with its in-situ cultural space.
基金Supported by the National Natural Science Foundation of China(50475040)the Aeronautical Science Foundation of China(2005ZH52060)the Natural Science Foundation of Jiangsu Province(BK2006723)~~
文摘The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction（XRD）. The effects of brazing atmospheres on the as-brazed NiCr brazing alloy composite structures and interracial microstructure are studied between diamond grits and brazing alloy. Results show that： （1） There are different composite structures of as-brazed NiCr brazing alloy under different oxygen partial pressures in vacuum and argon gas. B203 exists on the surface of the brazed samples under argon gas furnace brazing. It indicates that oxygen plays an important role in the resultants of as-brazed NiCr brazing alloy during the brazing process. （2） There are different interfacial microstructures in different brazing atmospheres, but the main reaction product is chromium carbides. The chromium carbides in argon gas furnace brazing grow in a disordered form, but those in vacuum furnace brazing grow radiated. And the scale of grains in argon gas is smaller than those in vacuum.
基金the National Natural Science Foundation of China (50772030, 50572024)
文摘BaCe0.45Zr0.45M0.1O3-δ （M=Y, In） and BaCe0.9Y0.1O3-δ were prepared through the conventional solid state reaction route. The chemical stability was investigated in hydrogen, carbon dioxide, and boiling water. Crystalline phase and microsa-ucture of the proton conductor before and after stability test were measured with X-ray diffraction （XRD） and scanning electron microscopy （SEM）, respectively. The results showed that all materials were quite stable in H2 atmosphere. In CO2 atmosphere, BaCe0.45Zr0.45M0.1O3-δ（M=Y, In） were relatively stable, while Bafe0.9Y0.1O3-δ decomposed. In boiling water, BaCe0.9Y0.1O3-δ was quickly decomposed into Ba（OH）2 and corresponding oxide. BaCe0.45Zr0.45M0.1O3-δ slightly reacted with boiling water and some amorphous phases were formed. However, BaCe0.45Zr0.45In0.1O3-δ was observed to exhibit better stability than BaCe0.45Zr0.45Y0.1O3-δ in water. The experimental results were interpreted in terms of thermodynamic data and tolerance factor.
基金Project supported by the Excellent Young Scientists Fund from the National Science Foundation of China(NSFC)(21622106)other projects from the NSFC(21771117,21805167).
文摘So far,it is still a controversial issue which status of gold species is a better active site for catalyzing CO oxidation.Herein,the influence of the different atmospheres pretreatment(oxidative and reductive)on gold state of Au/La-CeOx(1 wt%gold loading)catalyst during CO oxidation was studied.The changes of Au species were monitored by combined in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS)and X-ray photoelectron spectroscopy(XPS).For the sample pretreated with oxidative atmosphere,the data show that the initial Au^(3+)is transformed to Au^(δ+)(0<δ<1)during CO oxidation,which is a key step to lead to higher reactivity.For the sample after reductive atmosphere pretreatment,Au^(δ+)is mixed with a small amount of Au^(0)which can be converted to Au^(δ+)with the increase of temperature in reaction.Meanwhile,the sample always maintains high activity during the reaction.Therefore,the Au®+obtained by reductive pretreatment is more active than the Au^(3+)obtained by oxidative treatment in catalyzing CO oxidation.
基金financially supported by the National Natural Science Foundation of China (Nos. 51372019, 51074009, and 50874013)the National Science and Technology Supporting Program (No. 2011BAB03B02)
文摘Regenerated MgO-CaO brick samples containing 80wt%, 70wt%, and 60wt% MgO were prepared using spent MgO-CaO bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K for 2 h under an air atmosphere and under an isolating system. The microstructure, mechanical properties at room temperature, and hydration resistance of the regenerated samples were measured and compared. The results indicated that the isolating sintering generated a strongly reducing atmosphere as a result of the incomplete combustion of paraffin, and the partial oxygen pressure was approximately 6.68 × 10^-7 Pa. The properties of the regenerated bricks sintered under air conditions were all higher than those of the bricks sintered under a reducing atmosphere. The deterioration of the bricks was a result of MgO reduction and a decrease in the amount of liquid phase formed during sintering under a reducing atmosphere.
基金Supported by the National Natural Science Foundation of Chinasponsored by the National Natural Science Foundation of China(No. 10673031) as well as the National Basic Research Program of China (973) under grant num-ber G2006CB806301.
文摘A new way to measure the departure from thermodynamic equilibrium is proposed based on the departure factor which evaluates the deviation from a Boltzmann level distribution, used by Short and Hauschildt （2005） and others. The way is based on an explicit relationship describing the departure factor as a function of line to continuum source, dynamic temperature and line photon frequency, under three assumptions that the scattering can be neglected, the background continuum can be treated as a Planck function, and finally the complete redistribution can be true. It has the advantage that the departure can be very conveniently evaluated from the spectral analysis with only the radiative transfer involved. Some physical insights are recovered for some extreme cases. Some example calculations of the departure are presented for the quiet Sun, faint solar flare and strong solar flare for the generally used solar chromospheric lines： Hα, Hβ, CaII H, K and triplet. It is revealed that in the case of solar flares, the departure is less than thermodynamic equilibrium along the larger depth range than in the quiet sun due to chromospheric condensation. It becomes hard to distinguish the departures for the different lines of the same atom or ion. It is expected that this investigation can be constructive for studying stellar atmospheres in cases where the three assumptions are close to reality.
文摘Raney-Copper(R-Cu)catalyst was prepared and its sintering behaviour in atmospheres at teperature 300℃-600℃ was detected by methods of SSA,PSD,XRD and SEM.It was found that sintering of R-Cu started from much lower temperature than the melting point of copper.Changes both on the surface and in the body phase were discovered.There is a rule in the extent of sintering for R-Cu in different atmospheres which is related to the adsorption of the particular gases molecules on the surface of the catalyst.Dynamical equations of the surface decrease is established and the mechanism of sintering is discussed.Calculations of quantum mechanics give the similar results.
基金Funded by the National "Twelfth Five-Year" Plan for Science&Technology Support of China(No.2011BAE29B02))
文摘The effects of atmospheres and precursors on MnOx/TiO2 catalysts were studied, which were prepared by the impregnation method and tested for their NOx conversion activity in ammonia selective catalytic reduction （NH3-SCR） reactions. Results showed that the manganese carbonate （MC） precursor caused mainly Mn2O3, while the manganese nitrate （MN） precursor resulted primarily in MnO2 and the manganese sulfate （MS） precursor was unchanged. The manganese acetate （MA） precursor leaded obtaining a mixture of Mn2O3 and Mn304. NOn conversion decreased in the following order： MA/TiO2 〉 MC/TiO2 〉 MN/TiO2 〉 MS/TiO2 〉 P25, with a calcination temperature of 773 K in air. Catalysts that were prepared by MA and calcined in oxygen performed strong interaction between Ti and Mn, while MnTiO3 was observed. Compared to the catalysts calcined in nitrogen, those calcined in oxygen had larger diameter and smaller surface area and pore. Catalysts that were prepared by MA and calcined in nitrogen tended to gain higher denitration rates than those in air, since they could be prepared with significant specific surface areas. NO., conversion decreased with calcination atmospheres： Nitrogen〉 Air〉 Oxygen. Meanwhile, amorphous Mn2O3 turned into crystalline Mn2O3, when the temperatures increased from 673 to 873 K.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Nos.2020R1A4A4079954 and 2021R1A2B5B01001448)。
文摘In this study,water-dispersible graphitic carbon nitride(g-C_(3)N_(4))photocatalysts were successively prepared through the chemically oxidative etching of bulk g-C_(3)N_(4) that was polymerized thermally in different calcination atmospheres such as air,CO_(2),and N_(2).The different calcination atmospheres directly influenced the physicochemical and optical properties of both bulk and water-dispersible g-C_(3)N_(4),changing the photocatalytic degradation behavior of methylene blue(MB)and tetracycline hydrochloride(TCHCl)for water-dispersible g-C_(3)N_(4).The bubble-burst process in the thermal polymerization of thiourea produced defective edges containing C=O groups that preferred substituting the C-NHx groups over bulk g-C_(3)N_(4).In the oxygen-free N_(2) atmosphere among the different calcination atmospheres,more C=O functional groups were generated on the defective edges of bulk g-C_(3)N_(4),resulting in the highest N vacancy of the tri-s-triazine structure.During the successive chemical oxidation,S-or O-containing functional groups were introduced onto water-dispersible g-C_(3)N_(4).The water-dispersible g-C_(3)N_(4) photocatalyst from the oxygen-free N_(2) atmosphere(NTw)contained the most O-and S-functional groups on the g-C_(3)N_(4) surface.Consequently,NTw exhibited the highest photocatalytic activity in the MB and TC-HCl photodegradation because of its slowest recombination process,which was ascribed to the unique surface properties of NTw such as abundant functional groups on the defective edges and N-deficient property.
基金This study was conducted with financial support from the National Natural Science Foundation of China(No.51574023).
文摘The microstructure of coke has an important influence on its thermal properties.The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation.The results showed that the isotropic components had a more vigorous reaction than the anisotropic components,and the solution loss reaction of the fine-grained mosaic structure was faster than that of the coarse-grained mosaic structure under the CO2 and H2O atmospheres.The coarse-grained mosaic structure and the flowing structure had a relatively higher anti-erosion ability in the CO2 atmosphere than in the H2O atmosphere,and there was no distinct difference in the solution loss of the isotropic structure under the CO2 and H2O atmospheres.The electron probe microanalysis showed that the Al-Si-Fe compounds in the carbon matrix had positive influence on the solution loss reaction of the anisotropic structure.The iron compounds were able to destroy the pore walls of coke and accelerate the solution loss rate of coke.
基金supported by the National Natural Science Foundation of China(No.51202116)the Ministry of Science and Technology of China(No.2015AA034603)
文摘The catalytic activity and durability of Rh/ZrO2 catalyst were investigated compared with Rh/Al2O3 catalyst under diverse aging atmospheres, including lean, rich and lean–rich cyclic aging atmospheres, to simulate the real working conditions of three-way catalyst.Oxidation states and microstructures of rhodium species were investigated to correlate with the catalytic performance of the catalysts. The catalytic performance and durability of the Rh catalyst under diverse aging atmospheres were drastically enhanced by ZrO2 support. ZrO2 support was confirmed to be able to effectively inhibit rhodium sintering even under diverse aging conditions. It can also successfully keep Rh species in an active low-valence state on the surface of the catalyst. The superiority of ZrO2 support compared to Al2O3 was verified by the Rh-based monolith catalyst.
基金supported by the Ninth Fiveyear Key Project from State Department of Science and Technology(99-010-01-03)the Young Scientist Knowledge Innovation Project of the Chinese Academy of Sciences.
文摘The changes in physiological characteristics, quality and storability of the sweet cherry (Pru-mus avium L. cv. Hongdeng) stored in controlled atmospheres (CA), in modified atmosphere packages (MAP) and in air (CK) were investigated in this paper. The results showed that CA and MAP treatments significantly inhibited fruit rot and flesh browning, kept firmness and fruit color, reduced ethylene and ethanol content in pulp, slowed down the increase of polyphenol oxidase (PPO) and peroxidase (POD) activity and malondialdehyde (MDA) content in comparison with CK. Meanwhile, CA treatments showed a better benefit of reducing ethylene and ethanol contents, inhibiting PPO and POD activities, declining rot rate and browning index compared to MAP. The fruit could be stored in CA conditions for 60 days without any off-flavor. The sweet cherries kept in CA with 5% O2 + 10% CO2 showed a better storability than that in CA with 5% O2 + 5% CO2.
基金supported by National Natural Science Foundation of China (Nos.21706167 and 21776179)Fok Ying Tung Education Foundation (161108)+2 种基金the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT_15R46)Yangtze River Scholar Research Project of Shihezi University (No.CJXZ201601)the Start-Up Foundation for Young Scientists of Shihezi University (RCZX201507)
文摘Ru-based catalysts modified in different atmospheres by plasma technology were prepared to catalyze the acetylene hydrochlorination reaction.The(Ru/AC)-N_(2)(AC = activated carbon)catalyst yielded by the plasma modification of Ru/AC catalyst in N2 atmosphere exhibits the best catalytic performance with a stable C_(2)H_(2) conversion of 87.2%;a relative increase of 27.1%in C2H2 conversion was achieved compared with that of the untreated Ru/AC catalyst.The results of the analysis revealed that the modification produced a mutual effect between the generated function groups on carrier AC and the active components, which can disperse and yield more active species in the fresh catalysts.These are benefits of enhancing the activity of the catalysts.Moreover, the modification can restrain coke formation and inhibit the loss of active species in the reaction, as well as strengthen the adsorption ability of reactants on the catalysts.These are benefits of improving the catalysts’ performance.
文摘The quality of Yi＇an gas coal before and after low temperature upgrading under either a N2 or H2 atmosphere was examined by thermogravimetric and infrared analyses. The effect of upgrading on the prepared coke quality was analyzed. The results show that the carboxyl and phenolic hydroxyls in the coal molecular structure are removed after upgrading by low temperature pyrolysis under either N2 or Hz atmospheres. This improves coal caking properties to a certain extent. The upgrading effect under a Hz atmosphere is remarkably better than the effect observed after upgrading under N2. Compared to coke obtained from raw coal, the compressiveand micro-strength of the cokes obtained from upgraded coal are greatly improved. The effect on coke reactivity with CO2 is not significant. The best upgrading temperature for Yi＇an gas coal under either a N2 or H2 atmosphere is 250 or 275 ℃ respectively.
文摘The line formation process in stellar magnetized atmospheres is studied by observing the wavelength- dependence of Stokes contribution functions. The influence of magnetic field on the escape line photon distribution and line absorption is obtained by comparing with the null magnetic field case. Two models airs adopted. One assumes limited distributions of both the line absorption and magnetic field where a hypothetical magneto-sensitive line is formed. The other is a model atmosphere of sunspot umbra in which MgI 5172.7 forms. It is found that the magnetic field influences the formation region of Stokes I at wavelengths sufficient close to the Zeeman splitting points ±△ H. The formation regions at wavelengths far away from the Zeeman splitting points generally show a non-magnetic behaviour. Further, if the line core is split by the Zeeman effect, the line formation core introduced in the previous paper disappears. On the other hand, Stokes Q, U, V at each wavelength within the line form in the same layers where both the line absorption and magnetic field are present in the models accepted for the lines used. When the line absorption and magnetic field ubiquitously exist, the formation regions of the T peaks or valleys of Stokes Q, U and those of σ of Stokes V generally cover the widest depth range. It is pointed out that such a study is instructive in the explanation of solar polarized filtergrams. It can tell us at each observation point where the received line photons of wavelengths within the bandpass come from and where their polarization states are formed or give us the distributions of these photons as well as their polarization intensities. Thus a three-dimensional image can be constructed for a morphologic study of the observed area from serial filtergrams.
文摘Vertical profiles of seasonally varying pressure, temperature, water vapor, and trace gases （O3, N2O, CO, CH4）, representing atmospheric conditions up to a height of 100 km over the East Asia region （30°-50°N, 110°-150°E） were constructed by using various observation data, model outputs of atmospheric thermodynamic parameters, and gaseous concentrations. Optical characteristics of the obtained East Asia reference atmospheres were compared with those from typical midlatitude summer and winter atmospheres. It was noted that, in the water vapor field, there are major differences between the two model atmospheres during the summer. The resultant impact during the summer of water vapor difference on incoming solar fluxes at the surface and emitted terrestrial fluxes at the top of the atmosphere are 14.3 W m^-2 and 6.5 W m^-2, respectively. On the other hand, the winter difference between East Asian and midlatitude atmospheres appears to be insignificant. Reference atmospheres for the spring and fall are also available. Utilizing the constructed atmospheric profiles as inputs to the radiative transfer model, it is expected that the constructed seasonally varying reference atmospheres can facilitate better descriptions of optical properties in East Asia.
基金the B-type Strategic Priority Program of the Chinese Academy of Sciences,CNSA D020205 and Grant No.XDB18010104the support from a CSH fellowship at Universitat Bernthe support from the Beijing Innovation Project。
文摘Geological and astronomical observations on the‘‘lava world’’of the rocky planet,with additional theoretical interpretation of Moon’s crustal formation,bring up to the occurrence of the magma ocean and lava ponds,which inherits accretion energy of rocky planetesimal and evolves with subsequent energy releases.Hemispherical or global oceans of silicate melt could be a widespread lava phase after rocky planet accretion as well as large impact and could persist on planets on orbits around other stars for various time scales.The processes of magma ocean formation and solidification change the phases,cause element segregations,and strongly affect the earliest compositional differentiation and volatile content of the terrestrial planets.They form the starting point for cooling to mildly habitable conditions and for the onset of thermally driven solid-state mantle convection.The formation and crystallization of magma oceans also influence the assembly of a core,the origin of a crust,initiation of tectonics,and formation of an atmosphere.It is inevitable to investigate the magma ocean dynamics of such an early period of Earth evolution.This review focuses on the internal dynamics of magma oceans after planetesimal accretion and planetary formation including turbulence,particle motion,and solid-state convection,which determine the associated processes of cooling,crystallization,and convection of magma ocean.Geochemical differentiation is discussed correspondingly.The thermodynamics of equilibration between a magma ocean and an overlying,outgassed atmosphere is also discussed,highlighting the need for more data on volatile solubility in silicate melts.The effect of coupling between magma ocean and solid-state mantle convection is also discussed.
基金supported by the National Natural Science Foundation of China (11661161014)Tsinghua University Initiative Science Research Program (523001028)
文摘Atmospheric escape is a key process controlling the long term evolution of planets. Radiative cooling competes for energy against atmospheric escape in planetary upper atmospheres. In this work, we use a population balance method and a Monte Carlo model to calculate the previously ignored emissions of metals(C, N, O and their ions) and compare them with radiative recombination of H II and Ly-α emission of H I, which are the most efficient cooling mechanisms currently recognized in the upper atmospheres of hot Jupiters.The results show that the emissions of C, N, O and their ions are strong non-linear functions of environmental parameters(temperature,density, etc.) and are likely to be efficient cooling mechanisms in the upper atmospheres of close-in exoplanets.
