Nitrogen doping has significant effects on the photocatalytic performance of ceria(CeO_(2)),and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies(OVs)is of great significance for...Nitrogen doping has significant effects on the photocatalytic performance of ceria(CeO_(2)),and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies(OVs)is of great significance for further investigation,and the specifically exposed crystal faces of CeO_(2)may have an impact on the performance of nitrogen doped CeO_(2).Herein,nitrogen-doped CeO_(2)with different morphologies and exposed crystal faces was prepared,and its performances in the photocatalytic degradation of tetracycline(TC)or hydrogen production via water splitting were evaluated.Density functional theory(DFT)was used to simulate the band structures,density of states,and oxygen defect properties of different CeO_(2)structures.It was found that nitrogen doping and OVs synergistically promoted the catalytic activity of nitrogen-doped CeO_(2).In addition,the exposed crystal faces of CeO_(2)have significant effects on the introduction of nitrogen and the ease of OV generation,as well as the synergistic effect of nitrogen doping with OVs.Among them,the rod-like nitrogen-doped CeO_(2)with exposed(110)face(R-CeO_(2)-NH_(3))showed a photocatalytic degradation ratio of 73.59%for TC and hydrogen production of 156.89μmol/g,outperforming other prepared photocatalysts.展开更多
Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine(TEA).Semiconductor tin oxide(SnO_(2))is one of the most widely used sensing materials for metal oxide g...Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine(TEA).Semiconductor tin oxide(SnO_(2))is one of the most widely used sensing materials for metal oxide gas sensors.In recent years,a lot of binary ternary compound researches have been carried out.In this paper,five different SnO_(2) samples were synthesized by simple synthesis method to understand the internal relationship and obtain different gas sensing characteristics.Based on the low temperature nitrogen adsorption tests and the atomic arrangement model,it can be inferred that different exposed surfaces play a key role in TEA sensing properties.In addition,the TEA sensing activity relationship of SnO_(2) exposed crystal faces is proposed as listed:(200)>(101)>(110).展开更多
This paper describes the effect of the in situ hydrolysis of 2-cyanopyridine and its derivatives on the synthesis of dimethyl carbonate（DMC） from CO2 and methanol over CeO2.2-Cyanopyridine.with the highest electroni...This paper describes the effect of the in situ hydrolysis of 2-cyanopyridine and its derivatives on the synthesis of dimethyl carbonate（DMC） from CO2 and methanol over CeO2.2-Cyanopyridine.with the highest electronic charge number of the carbon in the cyanogroup,is the most effective agent to accelerate the desired reaction by a decrease of water.CeO2（110） planes are active for the hydrolysis of 2-cyanopyridine,further enhancing the DMC formation by in situ removal of water effectively.The DMC yield is improved drastically up to 378.5 mmol g cat^-1 from 12.8 mmol g cat^-1 with the in situ hydrolysis of 2-cyanopyridine over rod-CeO2（1 1 0） catalyst.展开更多
With regard to green chemistry and sustainable development,the fixation of CO_(2) into epoxides to form cyclic carbonates is an attractive and promising pathway for CO_(2) utilization.Metal oxides,renowned as promisin...With regard to green chemistry and sustainable development,the fixation of CO_(2) into epoxides to form cyclic carbonates is an attractive and promising pathway for CO_(2) utilization.Metal oxides,renowned as promising eco-friendly catalysts for industrial production,are often undervalued in terms of their impact on the CO_(2)addition reaction.In this work,we successfully developed ZnO nanoplates with(002)surfaces and ZnO nanorods with(100)surfaces via morphology-oriented regulation to explore the effect of crystal faces on CO_(2) cycloaddition.The quantitative data obtained from electron paramagnetic resonance spectroscopy indicated that the concentration of oxygen vacancies on the ZnO nanoplate surfaces was more than twice that on the ZnO nanorod surfaces.Density functional theory calculations suggested that the(002)surfaces have lower adsorption energies for CO_(2) and epichlorohydrin than the(100)surfaces.As a result,the yield of cyclochloropropene carbonate on the ZnO nanoplates(64.7%)was much greater than that on the ZnO nanorods(42.3%).Further evaluation of the reused catalysts revealed that the decrease in the oxygen vacancy concentration was the primary factor contributing to the decrease in catalytic performance.Based on these findings,a possible catalytic mechanism for CO_(2) cycloaddition with epichlorohydrin was proposed.This work provides a new idea for the controllable preparation of high-performance ZnO catalysts for the synthesis of cyclic carbonates from CO_(2) and epoxides.展开更多
Although atom configuration in crystals is precisely known thanks to imaging techniques, there is no experimental way to know the exact location of bonds or charges. Many different representations have been proposed, ...Although atom configuration in crystals is precisely known thanks to imaging techniques, there is no experimental way to know the exact location of bonds or charges. Many different representations have been proposed, yet no theory to unify conceptions. The present paper describes methods to derive bonds and charge location in double-face-centered cubic crystals with 4 and 6 atoms per unit cell using two novel rules introduced in earlier works: the even-odd and the isoelectronicity rules. Both of these rules were previously applied to ions, molecules and some solids, and the even-odd rule was also tested on two covalent crystal structures: centered-cubic and single-face-centered cubic crystals. In the present study, the diamond-like structure was subjected to the isoelectronicity rule in order to derive Zinc-blende structures. Rock-salt-like crystals were derived from each other using both rules. These structures represent together more than 230 different crystals. Findings for these structures are threefold: both rules describe a very sure method to obtain valid single covalent-bonded structures;single covalent structures can be used in every case instead of the classical ionic model;covalent bonds and charges positions do not have any relation with the valence number given in the periodic table.展开更多
A crystal is a highly organized arrangement of atoms in a solid, wherein a unit cell is periodically repeated to form the crystal pattern. A unit cell is composed of atoms that are connected to some of their first nei...A crystal is a highly organized arrangement of atoms in a solid, wherein a unit cell is periodically repeated to form the crystal pattern. A unit cell is composed of atoms that are connected to some of their first neighbors by chemical bonds. A recent rule, entitled the even-odd rule, introduced a new way to calculate the number of covalent bonds around an atom. It states that around an uncharged atom, the number of bonds and the number of electrons have the same parity. In the case of a charged atom on the contrary, both numbers have different parity. The aim of the present paper is to challenge the even-odd rule on chemical bonds in well-known crystal structures. According to the rule, atoms are supposed to be bonded exclusively through single-covalent bonds. A distinctive criterion, only applicable to crystals, states that atoms cannot build more than 8 chemical bonds, as opposed to the classical model, where each atom in a crystal is connected to every first neighbor without limitation. Electrical charges can be assigned to specific atoms in order to compensate for extra or missing bonds. More specifically the article considers di-atomic body-centered-cubic, tetra-atomic and dodeca-atomic single-face-centered-cubic crystals. In body-centered crystals, atoms are interconnected by 8 covalent bonds. In face-centered crystal, the unit cell contains 4 or 12 atoms. For di-element crystals, the total number of bonds for both elements is found to be identical. The neutrality of the unit cell is obtained with an opposite charge on the nearest or second-nearest neighbor. To conclude, the even-odd rule is applicable to a wide number of compounds in known cubic structures and the number of chemical bonds per atom is not related to the valence of the elements in the periodic table.展开更多
The stability of the shapes of crystal growth face and dissolution face in a two-dimensional mathematical model of crystal growth from solution under microgravity is studied. It is proved that the stable shapes of cry...The stability of the shapes of crystal growth face and dissolution face in a two-dimensional mathematical model of crystal growth from solution under microgravity is studied. It is proved that the stable shapes of crystal growth face and dissolution face do exist, which are suitably shaped curves with their upper parts inclined backward properly.The stable shapes of crystal growth faces and dissolution faces are calculated for various values of parameters, Ra, Pr and Sc. It is shown that the stronger the convection relative to the diffusion in solution is, the more backward the upperparts of the stable crystal growth face and dissolution face are inclined. The orientation and the shape of dissolution face hardly affect the stable shape of crystal growth face and vice versa.展开更多
A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with ...A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with the modes and intensities of dislocation interactions between slip systems active in the crystal; and,hence,may be predicted by the location of its tensile axis in the crystallographic triangle.This model has successfully explained the different behaviours of double-slip crystals and multi-slip behaviours of some crystals with orientations usually con- sidered as single-slip ones.展开更多
Four kinds of calcium oxalate monohydrate(COM)crystals with the size of(1.5±0.4),(3.5±0.5),(5.5±0.5)and(9.5±1)μm respectively were synthesized by changing reaction temperature,solvent,additive and...Four kinds of calcium oxalate monohydrate(COM)crystals with the size of(1.5±0.4),(3.5±0.5),(5.5±0.5)and(9.5±1)μm respectively were synthesized by changing reaction temperature,solvent,additive and stirring speed.Their physiochemical properties were comparatively investigated.It is beneficial to obtain crystal with small size by adding additive Na3Cit,increasing stirring speed,reducing reaction temperature or decreasing dielectric constant of the solvent.The results of X-ray diffraction revealed that all these crystals are single-phase COM crystals.With the increase of crystal size from 1 to 9μm,COM crystals changed from rough blunt round to smooth thin sheet,the(101)crystal face of COM with high charge density increased,and both the charge density and the absolute value ofζpotential on crystal surface increased,leading an increase of the stability of crystal suspension.The cytotoxicity of these COM crystals to human kidney proximal tubular epithelial(HK-2)cells is negatively correlated with the crystal size.展开更多
In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmiss...In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmission electron microscopy(HRTEM)results show that CeO_(2)-to exposes composite{100}and{111}facets,while CeO_(2)cubic(CeO_(2)-c)and CeO_(2)octahedral(CeO_(2)-o)only expose single crystal facets of{100}plane and{111}plane,respectively.Interestingly,this CeO_(2)-to photocatalyst exhibits remarkable photooxidation performance of gaseous acetaldehyde(CH_(3)CHO)degradation,in which CO_(2)generation value reaches 1.78 and 7.97-times greater than that of CeO_(2)-c and CeO_(2)-o,respectively.In addition,the active species trapping experiment signifies that superoxide(·O_(2)^(-))and holes(h^(+))are the main reactive substances during the CH_(3)CHO degradation process,and the electron paramagnetic resonance(EPR)spectra indicates that the former is the major contributor.Notably,the electron transfer mechanism between CeO_(2)-to{100}and{111}facets and the surface oxygen adsorption ability are revealed via density functional theory(DFT)calculations.It is also confirmed that{100}facets are more conducive to the absorption of acetaldehyde than{111}facets.Finally,a reasonable mechanism for improved photocatalytic CH_(3)CHO degradation on CeO_(2)-to is proposed based on relevant experiments and DFT calculations.This study demonstrates that the systematic development of surface homojunction structured photocatalysts can efficiently increase the degradation activity for volatile organic compounds(VOCs).It also offers additional direction for optimizing the photocatalytic activity of other ceriumbased photocatalysts.展开更多
The magnesium alloy grew in a fashion of cellular crystals during the process of unidirectional solidification, and the {0001} crystal face orientation in the cast ingot of the magnesium alloy was studied. The theoret...The magnesium alloy grew in a fashion of cellular crystals during the process of unidirectional solidification, and the {0001} crystal face orientation in the cast ingot of the magnesium alloy was studied. The theoretical model and methodology were set up, and a cor-responding experiment was carried out to verify the theoretical analysis results. The experimental results indicate that the {0001} crystal face of magnesium crystals parallels to the width direction for the thin-plate cast ingot when the magnesium grows in a manner of cellular crystals. The separation angle between the {0001} crystal face of magnesium crystals and the vertical axis line of the cast ingot is about 62° for the circular column cast ingot, which distributes in cone-type. The theoretical analysis results are basically in agreement with the experimental ones of previous literatures and this paper.展开更多
Zinc acetate is used as a raw material to synthesize the desired ZnO in hot solvent by controlling the amount of citric acid(CA)added.Notably,the amount of CA added has a significant relationship with the control of t...Zinc acetate is used as a raw material to synthesize the desired ZnO in hot solvent by controlling the amount of citric acid(CA)added.Notably,the amount of CA added has a significant relationship with the control of the morphology of ZnO.Spherical ZnO wrapped in nanosheets is synthesized through the secondary crystallization of Zn^(2+).The optical properties of the ZnO sample are tested through the degradation of organic pollutants.Notably,the photocatalytic properties of ZnO vary with the different amounts of CA added.Exposure of the active crystal face increases the photocatalytic activity of ZnO.In addition,the number of defects on the surface of the ZnO sample increases because of its large specific surface area,thus changing the bandgap of ZnO.Therefore,the resulting sample can respond under visible light.展开更多
To study the extraction difficulty of lithium ions from various crystal planes of Li2 TiO3, according to the first principle, four representative crystal surfaces of Li2TiO3（precursor）,（-133）,（-206）,（002） and...To study the extraction difficulty of lithium ions from various crystal planes of Li2 TiO3, according to the first principle, four representative crystal surfaces of Li2TiO3（precursor）,（-133）,（-206）,（002） and（-131）, were selected to establish a model and to calculate the surface energy, bond length and population using Materials Studio 5.5（MS 5.5）. The results demonstrate that there is no direct relationship between the surface energy and the order of disappearance of the four diffraction peaks when lithium titanate is treated with hydrochloric acid, instead, the difficulty of Li~＋ extraction from various crystal faces corresponds to the Li-O bond strength. Lithium ion is easy to remove from（-133） and（-206） due to the relatively weak Li-O bond strength. In contrast, Li＋ extraction requires a longer time for（002） and（-131）.展开更多
The crystal plasticity was implemented in the finite element method(FEM) software ABAQUS through the user subroutine UMAT. By means of discretizing the space at the grain level with the Voronoi diagram method, a polyc...The crystal plasticity was implemented in the finite element method(FEM) software ABAQUS through the user subroutine UMAT. By means of discretizing the space at the grain level with the Voronoi diagram method, a polycrystal model was built and used in the FEM analysis. The initial orientation of each grain was generated based on the orientation distribution function(ODF). The developed model was successfully applied in simulation of polycrystalline aluminium samples deformed by the tensile tests. The theoretical strain—stress relation was in good agreement with the experimental result. The simulation results show that the grain size has significant effect on the deformation behavior. The initial plastic deformation usually occurs at grain boundaries, and multiple slip often results in an enhanced local hardening at grain boundaries.展开更多
Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nice single crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single...Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nice single crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single crystals are dirty due to intermolecular heterogeneity The crystal morphology changes with crystallization temperatures. Lozenge, truncated lozenge, hexagonal, rounded and elongated crystal morphologies have been found at much lower crystallization temperature than in linear polyethylene. The electron diffraction shows there is a possibility that the single crystals may have hexagonal packing in a crystallization temperature range. The lateral habits of single crystal are discussed based on roughening theories.展开更多
基金Project(52164025)supported by the National Natural Science Foundation of ChinaProject([2020]1Y219)supported by the Basic Research Program from the Science&Technology Department of Guizhou Province,China+2 种基金Project([2019]30)supported by the Training Project from Guizhou University,ChinaProject([2023]04)supported by the Guizhou University Innovation Talent Team Project,ChinaProject([2022]041)supported by the Natural Science Research Project of Guizhou Provincial Department of Education,China。
文摘Nitrogen doping has significant effects on the photocatalytic performance of ceria(CeO_(2)),and the possible synergistic effect with the inevitably introduced abundant oxygen vacancies(OVs)is of great significance for further investigation,and the specifically exposed crystal faces of CeO_(2)may have an impact on the performance of nitrogen doped CeO_(2).Herein,nitrogen-doped CeO_(2)with different morphologies and exposed crystal faces was prepared,and its performances in the photocatalytic degradation of tetracycline(TC)or hydrogen production via water splitting were evaluated.Density functional theory(DFT)was used to simulate the band structures,density of states,and oxygen defect properties of different CeO_(2)structures.It was found that nitrogen doping and OVs synergistically promoted the catalytic activity of nitrogen-doped CeO_(2).In addition,the exposed crystal faces of CeO_(2)have significant effects on the introduction of nitrogen and the ease of OV generation,as well as the synergistic effect of nitrogen doping with OVs.Among them,the rod-like nitrogen-doped CeO_(2)with exposed(110)face(R-CeO_(2)-NH_(3))showed a photocatalytic degradation ratio of 73.59%for TC and hydrogen production of 156.89μmol/g,outperforming other prepared photocatalysts.
基金financially supported by Shandong Provincial Key R&D Plan Program(No.2017GGX10135)Shandong Provincial Science Foundation(No.ZR2018LF013)。
文摘Demand for simple and effective gas sensing sensors is growing rapidly due to the growing threat of triethylamine(TEA).Semiconductor tin oxide(SnO_(2))is one of the most widely used sensing materials for metal oxide gas sensors.In recent years,a lot of binary ternary compound researches have been carried out.In this paper,five different SnO_(2) samples were synthesized by simple synthesis method to understand the internal relationship and obtain different gas sensing characteristics.Based on the low temperature nitrogen adsorption tests and the atomic arrangement model,it can be inferred that different exposed surfaces play a key role in TEA sensing properties.In addition,the TEA sensing activity relationship of SnO_(2) exposed crystal faces is proposed as listed:(200)>(101)>(110).
基金Financial support by Natural Science Foundation of China (NSFC,Nos.21176179,U1462122)the Program for New Century Excellent Talents in University(No.NCET-13-0411) is gratefully acknowledged
文摘This paper describes the effect of the in situ hydrolysis of 2-cyanopyridine and its derivatives on the synthesis of dimethyl carbonate（DMC） from CO2 and methanol over CeO2.2-Cyanopyridine.with the highest electronic charge number of the carbon in the cyanogroup,is the most effective agent to accelerate the desired reaction by a decrease of water.CeO2（110） planes are active for the hydrolysis of 2-cyanopyridine,further enhancing the DMC formation by in situ removal of water effectively.The DMC yield is improved drastically up to 378.5 mmol g cat^-1 from 12.8 mmol g cat^-1 with the in situ hydrolysis of 2-cyanopyridine over rod-CeO2（1 1 0） catalyst.
基金This work was supported by the National Natural Science Foundation of China(Grant No.22008177)the Natural Science Foundation of Inner Mongolia(Grant Nos.2023MS02004+2 种基金2023MS02011)the Foundation of Inner Mongolia Education Department(Grant No.JY20220266)and the Program for Young Talents of Science and Technology of Inner Mongolia(Grant No.NJYT23040).
文摘With regard to green chemistry and sustainable development,the fixation of CO_(2) into epoxides to form cyclic carbonates is an attractive and promising pathway for CO_(2) utilization.Metal oxides,renowned as promising eco-friendly catalysts for industrial production,are often undervalued in terms of their impact on the CO_(2)addition reaction.In this work,we successfully developed ZnO nanoplates with(002)surfaces and ZnO nanorods with(100)surfaces via morphology-oriented regulation to explore the effect of crystal faces on CO_(2) cycloaddition.The quantitative data obtained from electron paramagnetic resonance spectroscopy indicated that the concentration of oxygen vacancies on the ZnO nanoplate surfaces was more than twice that on the ZnO nanorod surfaces.Density functional theory calculations suggested that the(002)surfaces have lower adsorption energies for CO_(2) and epichlorohydrin than the(100)surfaces.As a result,the yield of cyclochloropropene carbonate on the ZnO nanoplates(64.7%)was much greater than that on the ZnO nanorods(42.3%).Further evaluation of the reused catalysts revealed that the decrease in the oxygen vacancy concentration was the primary factor contributing to the decrease in catalytic performance.Based on these findings,a possible catalytic mechanism for CO_(2) cycloaddition with epichlorohydrin was proposed.This work provides a new idea for the controllable preparation of high-performance ZnO catalysts for the synthesis of cyclic carbonates from CO_(2) and epoxides.
文摘Although atom configuration in crystals is precisely known thanks to imaging techniques, there is no experimental way to know the exact location of bonds or charges. Many different representations have been proposed, yet no theory to unify conceptions. The present paper describes methods to derive bonds and charge location in double-face-centered cubic crystals with 4 and 6 atoms per unit cell using two novel rules introduced in earlier works: the even-odd and the isoelectronicity rules. Both of these rules were previously applied to ions, molecules and some solids, and the even-odd rule was also tested on two covalent crystal structures: centered-cubic and single-face-centered cubic crystals. In the present study, the diamond-like structure was subjected to the isoelectronicity rule in order to derive Zinc-blende structures. Rock-salt-like crystals were derived from each other using both rules. These structures represent together more than 230 different crystals. Findings for these structures are threefold: both rules describe a very sure method to obtain valid single covalent-bonded structures;single covalent structures can be used in every case instead of the classical ionic model;covalent bonds and charges positions do not have any relation with the valence number given in the periodic table.
文摘A crystal is a highly organized arrangement of atoms in a solid, wherein a unit cell is periodically repeated to form the crystal pattern. A unit cell is composed of atoms that are connected to some of their first neighbors by chemical bonds. A recent rule, entitled the even-odd rule, introduced a new way to calculate the number of covalent bonds around an atom. It states that around an uncharged atom, the number of bonds and the number of electrons have the same parity. In the case of a charged atom on the contrary, both numbers have different parity. The aim of the present paper is to challenge the even-odd rule on chemical bonds in well-known crystal structures. According to the rule, atoms are supposed to be bonded exclusively through single-covalent bonds. A distinctive criterion, only applicable to crystals, states that atoms cannot build more than 8 chemical bonds, as opposed to the classical model, where each atom in a crystal is connected to every first neighbor without limitation. Electrical charges can be assigned to specific atoms in order to compensate for extra or missing bonds. More specifically the article considers di-atomic body-centered-cubic, tetra-atomic and dodeca-atomic single-face-centered-cubic crystals. In body-centered crystals, atoms are interconnected by 8 covalent bonds. In face-centered crystal, the unit cell contains 4 or 12 atoms. For di-element crystals, the total number of bonds for both elements is found to be identical. The neutrality of the unit cell is obtained with an opposite charge on the nearest or second-nearest neighbor. To conclude, the even-odd rule is applicable to a wide number of compounds in known cubic structures and the number of chemical bonds per atom is not related to the valence of the elements in the periodic table.
文摘The stability of the shapes of crystal growth face and dissolution face in a two-dimensional mathematical model of crystal growth from solution under microgravity is studied. It is proved that the stable shapes of crystal growth face and dissolution face do exist, which are suitably shaped curves with their upper parts inclined backward properly.The stable shapes of crystal growth faces and dissolution faces are calculated for various values of parameters, Ra, Pr and Sc. It is shown that the stronger the convection relative to the diffusion in solution is, the more backward the upperparts of the stable crystal growth face and dissolution face are inclined. The orientation and the shape of dissolution face hardly affect the stable shape of crystal growth face and vice versa.
文摘A dislocation interaction model has been proposed for cyclic deformation of fcc crystals.Ac- cording to this model,cyclic stress-strain responses and saturation dislocation structures of a crystal are associated with the modes and intensities of dislocation interactions between slip systems active in the crystal; and,hence,may be predicted by the location of its tensile axis in the crystallographic triangle.This model has successfully explained the different behaviours of double-slip crystals and multi-slip behaviours of some crystals with orientations usually con- sidered as single-slip ones.
文摘Four kinds of calcium oxalate monohydrate(COM)crystals with the size of(1.5±0.4),(3.5±0.5),(5.5±0.5)and(9.5±1)μm respectively were synthesized by changing reaction temperature,solvent,additive and stirring speed.Their physiochemical properties were comparatively investigated.It is beneficial to obtain crystal with small size by adding additive Na3Cit,increasing stirring speed,reducing reaction temperature or decreasing dielectric constant of the solvent.The results of X-ray diffraction revealed that all these crystals are single-phase COM crystals.With the increase of crystal size from 1 to 9μm,COM crystals changed from rough blunt round to smooth thin sheet,the(101)crystal face of COM with high charge density increased,and both the charge density and the absolute value ofζpotential on crystal surface increased,leading an increase of the stability of crystal suspension.The cytotoxicity of these COM crystals to human kidney proximal tubular epithelial(HK-2)cells is negatively correlated with the crystal size.
基金supported by the National Natural Science Foundation of China(Nos.21805191 and 22205084)Project funded by China Postdoctoral Science Foundation(No.2023M741039)+3 种基金Project funded by National&Local Joint Engineering Research Center for Mineral Salt Deep Utilization(SF202303)Project Funded by Yangzhou University(137013308),Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010982)Shenzhen Stable Support Project(No.20200812122947002),the Innovative Science and Technology Platform Project of Cooperation between Yangzhou City and Yangzhou UniversityPostgraduate Research&Practice Innovation Program of Jiangsu Province(Yangzhou University,No.XKYCX20_014)。
文摘In this study,the truncated octahedral CeO_(2)(CeO_(2)-to)with special morphology was prepared by the solvothermal method with oleic acid(OA)and oleamine(OM)as the morphology-directing agents.High-resolution transmission electron microscopy(HRTEM)results show that CeO_(2)-to exposes composite{100}and{111}facets,while CeO_(2)cubic(CeO_(2)-c)and CeO_(2)octahedral(CeO_(2)-o)only expose single crystal facets of{100}plane and{111}plane,respectively.Interestingly,this CeO_(2)-to photocatalyst exhibits remarkable photooxidation performance of gaseous acetaldehyde(CH_(3)CHO)degradation,in which CO_(2)generation value reaches 1.78 and 7.97-times greater than that of CeO_(2)-c and CeO_(2)-o,respectively.In addition,the active species trapping experiment signifies that superoxide(·O_(2)^(-))and holes(h^(+))are the main reactive substances during the CH_(3)CHO degradation process,and the electron paramagnetic resonance(EPR)spectra indicates that the former is the major contributor.Notably,the electron transfer mechanism between CeO_(2)-to{100}and{111}facets and the surface oxygen adsorption ability are revealed via density functional theory(DFT)calculations.It is also confirmed that{100}facets are more conducive to the absorption of acetaldehyde than{111}facets.Finally,a reasonable mechanism for improved photocatalytic CH_(3)CHO degradation on CeO_(2)-to is proposed based on relevant experiments and DFT calculations.This study demonstrates that the systematic development of surface homojunction structured photocatalysts can efficiently increase the degradation activity for volatile organic compounds(VOCs).It also offers additional direction for optimizing the photocatalytic activity of other ceriumbased photocatalysts.
基金supported by the Outstanding Innovation Team in Colleges and Universities of the Education Department of Liaoning Province, China (No.2007T078)Liaoning Natural Science Foundation (No.20092197)
文摘The magnesium alloy grew in a fashion of cellular crystals during the process of unidirectional solidification, and the {0001} crystal face orientation in the cast ingot of the magnesium alloy was studied. The theoretical model and methodology were set up, and a cor-responding experiment was carried out to verify the theoretical analysis results. The experimental results indicate that the {0001} crystal face of magnesium crystals parallels to the width direction for the thin-plate cast ingot when the magnesium grows in a manner of cellular crystals. The separation angle between the {0001} crystal face of magnesium crystals and the vertical axis line of the cast ingot is about 62° for the circular column cast ingot, which distributes in cone-type. The theoretical analysis results are basically in agreement with the experimental ones of previous literatures and this paper.
基金the National Natural Science Foundation of China(No.51602164)the Key Research Project of Shandong Province,China(No.2017GGX40121)+1 种基金the Young Doctor Cooperative Fund Project(No.2019BSHZ005)the Scientific Research Innovation Team in Colleges and Universities of Shandong Province,China.
文摘Zinc acetate is used as a raw material to synthesize the desired ZnO in hot solvent by controlling the amount of citric acid(CA)added.Notably,the amount of CA added has a significant relationship with the control of the morphology of ZnO.Spherical ZnO wrapped in nanosheets is synthesized through the secondary crystallization of Zn^(2+).The optical properties of the ZnO sample are tested through the degradation of organic pollutants.Notably,the photocatalytic properties of ZnO vary with the different amounts of CA added.Exposure of the active crystal face increases the photocatalytic activity of ZnO.In addition,the number of defects on the surface of the ZnO sample increases because of its large specific surface area,thus changing the bandgap of ZnO.Therefore,the resulting sample can respond under visible light.
基金Funded partly by the Key Project of Natural Science of Sichuan Provincial Education Department(No.16ZA0309)the Doctoral Research Start-up Funding(No.15B16)
文摘To study the extraction difficulty of lithium ions from various crystal planes of Li2 TiO3, according to the first principle, four representative crystal surfaces of Li2TiO3（precursor）,（-133）,（-206）,（002） and（-131）, were selected to establish a model and to calculate the surface energy, bond length and population using Materials Studio 5.5（MS 5.5）. The results demonstrate that there is no direct relationship between the surface energy and the order of disappearance of the four diffraction peaks when lithium titanate is treated with hydrochloric acid, instead, the difficulty of Li~＋ extraction from various crystal faces corresponds to the Li-O bond strength. Lithium ion is easy to remove from（-133） and（-206） due to the relatively weak Li-O bond strength. In contrast, Li＋ extraction requires a longer time for（002） and（-131）.
文摘The crystal plasticity was implemented in the finite element method(FEM) software ABAQUS through the user subroutine UMAT. By means of discretizing the space at the grain level with the Voronoi diagram method, a polycrystal model was built and used in the FEM analysis. The initial orientation of each grain was generated based on the orientation distribution function(ODF). The developed model was successfully applied in simulation of polycrystalline aluminium samples deformed by the tensile tests. The theoretical strain—stress relation was in good agreement with the experimental result. The simulation results show that the grain size has significant effect on the deformation behavior. The initial plastic deformation usually occurs at grain boundaries, and multiple slip often results in an enhanced local hardening at grain boundaries.
基金This work was jointly supported by National Natural Science Foundation of China and a Grant-in-Aid for Scientific Research from the Ministry of Education of China.
文摘Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nice single crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single crystals are dirty due to intermolecular heterogeneity The crystal morphology changes with crystallization temperatures. Lozenge, truncated lozenge, hexagonal, rounded and elongated crystal morphologies have been found at much lower crystallization temperature than in linear polyethylene. The electron diffraction shows there is a possibility that the single crystals may have hexagonal packing in a crystallization temperature range. The lateral habits of single crystal are discussed based on roughening theories.
