We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumpt...We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.展开更多
In ordinary differential equations, structural stability of hyperbolic fixed points is a classical result, but the proof of this result in [2] has same small mistake. In this paper,we will correct the above mistake by...In ordinary differential equations, structural stability of hyperbolic fixed points is a classical result, but the proof of this result in [2] has same small mistake. In this paper,we will correct the above mistake by using the Hartman theorem and its idea.展开更多
The reliable functioning of ion channels should be closely related to their structural stability. The selectivity filter in the KcsA potassium channel possesses four stable ion binding sites that can coordinate nearly...The reliable functioning of ion channels should be closely related to their structural stability. The selectivity filter in the KcsA potassium channel possesses four stable ion binding sites that can coordinate nearly fully dehydrated ions, whereas only two of such binding sites exist in the non-selective NaK channel, and none of them is found in the NavAb sodium channel. Here we show that the stability of the selectivity filters in these tetrameric cation channels is inversely correlated with the number of stable binding sites by extensive molecular dynamics simulations. While the presence of coordinated ions is crucial for the selectivity filters of the KcsA and NaK channels to stabilize the conformations in their crystal structures, the selectivity filter of the NavAb channel shows higher stability, independent of the presence of ions. We further show that the distinct repulsive electrostatic interactions between negatively charged oxygen atoms in the selectivity filter which form the stable binding sites are responsible for the different stability of these cation channels. The hydrogen bonding networks between residues in the selectivity filter and its adjacent pore helix also play an important role in maintaining stability. Together, these results provide important mechanistic insights into the structural stability of the selectivity filters in typical cation channels.展开更多
Degradation of the physical quality of the soil is a common problem encountered in agrosystems, particularly in the case of open field cropping systems in the northern areas of Côte d’Ivoire. Thus, the struc...Degradation of the physical quality of the soil is a common problem encountered in agrosystems, particularly in the case of open field cropping systems in the northern areas of Côte d’Ivoire. Thus, the structural stability of the soil, which is a good indicator of the sensitivity to threshing and to water erosion in relation to the accumulation of organic matter, was evaluated in two types of soil (Ferralsol and Cambisol) in cashew orchards, in two villages (Mahana and Sanankoro) producing cashew nuts, located the Department of Touba in the North West of Côte d’Ivoire. The objective of this study is to develop new technical routes that are better suited to further promote the sequestration of organic carbon in the soil. Soil samples were taken from open soil profiles at the two chosen sites to allow laboratory analyzes. The results indicate that the surface horizon of Cambisol (site 1) is more stable (Is = 0.78) than that of Ferralsol (site 2;Is = 1.08) with nevertheless relatively small thicknesses of horizons. The median horizons and those of depth, indicate a mediocre stability (Is vary from 1.03 to 1.62). In terms of the quantity of organic carbon, the estimated values vary from 1.96 to 4.53 t⋅ha−1 for Cambisol (site 1) and from 1.44 to 3.46 t⋅ha−1 for Ferralsol (site 2). These values remain relatively low especially at the level of the median horizons and those located in depths. Statistical tests have shown a very highly significant and negative association between the structural stability of soils and the amount of organic carbon in the different horizons. The relationship implies that organic carbon plays an important role in the structural stability of soil horizons under cashew tree orchards.展开更多
Metallo-supramolecular architectures that are constructed by coordination-driven self-assembly have received tremendous attention on account of their diverse yet molecular-level precise structures and broad applicatio...Metallo-supramolecular architectures that are constructed by coordination-driven self-assembly have received tremendous attention on account of their diverse yet molecular-level precise structures and broad applications.Of particular,metal cations and counter anions are fundamentally important in terms of self-assembly,characterization and property;however,their effects on the structural stabilities of metallo-supramolecular architectures have seldom been investigated.To address this issue,herein,a series of octahedral metallo-cages that are capable of tolerating with five metal cations(Pd^(2+),Cu^(2+),Ni^(2+),Co^(2+)and Zn^(2+)),and five counter anions(ClO_(4)^(–),OTf^(–),BF_(4)^(–),NTf_(2)^(–)and NO_(3)^(–))are constructed by the coordination-driven self-assembly of a well-designed tritopic isoquinoline-based ligand with corresponding metal salts.Structural stability studies show that metal cations and counter anions play a critical role in the stability of the resulting cages depending on their coordination abilities and stacking manners.This work provides deep insights in the ever-diversifying field of metallo-supramolecular chemistry,and will enable us to design more sophisticated assembled structure with desired function.展开更多
Two-dimensional nanomaterials(2DNMs)have attracted significant research interest due to their outstanding structural properties,which include unique electrical nanostructures,large surface areas,and high surface react...Two-dimensional nanomaterials(2DNMs)have attracted significant research interest due to their outstanding structural properties,which include unique electrical nanostructures,large surface areas,and high surface reactivity.These adaptable materials have outstanding physicochemical characteristics,making them useful in a variety of applications such as gas-sensing,electronics,energy storage,and catalysis.Extensive research has been conducted in the pursuit of high performance room-temperature(RT)gas sensors with good selectivity,high sensitivity,long-term stability,and rapid response/recovery kinetics.Metal oxides,transition metal chalcogenides,MXenes,graphene,phosphorene,and boron nitride have all been discovered as 2DNMs with strong potential for gas sensors.This review presents an in-depth analysis of current advances in 2DNM research.It includes synthetic techniques,structural stabilities,gas-sensing mechanisms,critical performance parameters,and factors influencing gas-sensing capabilities of 2DNMs.Furthermore,the present study emphasizes structural engineering and optimization methodologies that improve gas-sensing performance.It also highlights current challenges and outlines future research directions in the domain of tailoring 2DNMs for advanced RT gas sensors.This systematically designed comprehensive review article aims to provide readers with profound insights into gas detection,thereby inspiring the generation of innovative ideas to develop cutting-edge 2DNMs-based gas sensors.展开更多
Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution co...Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution content,P element completely enters into the lattice,forms[PO_(4)]tetrahedrons and partially replaces[SiO_(4)]tetrahedrons,which is confirmed by X-ray diffraction and X-ray photoelectron spectroscope measurements.Phosphorus substitution helps to suppress the change of coordination number of Mn and stabilize the material structure to some extent,obtaining better electrochemical performance in the early cycle.With the increase of P content,parts of P element exist in Li_(3)PO_(4)which distributes uniformly and co-exists with active substance.Electrochemical tests prove that existing Li_(3)PO_(4)has positive impacts on cycle and rate performance,and the lithium ion diffusion coefficient increases by about 14 times than pristine sample.Under the synergistic effects of phosphate substation and proper Li_(3)PO_(4),Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C shows enhanced electrochemical performances.展开更多
The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative format...The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.展开更多
Hybrid organic-inorganic perovskites are currently considered the most promising next-generation photovoltaic material.However,poor stability,arising from structural degradation under exposure to moisture,heat,and str...Hybrid organic-inorganic perovskites are currently considered the most promising next-generation photovoltaic material.However,poor stability,arising from structural degradation under exposure to moisture,heat,and strong current,remains a critical challenge for their device applications.Using ab initio nonadiabatic molecular dynamics,we demonstrate that methylamine fragments deriving from the dissociation of the methylammonium cation can undermine structural stability,produce deep hole traps,and decrease charge carrier lifetimes by 1-3 orders of magnitude.Both stability and charge lifetime can be restored by methylamine passivation with chlorines,which withdraw electrons from the lone electron pair of methylamine and bring the trap levels down into the valence band.The charge lifetime of the passivated system is even longer than that of the pristine perovskite.The simulations reveal the detailed microscopic mechanism underlying deterioration of perovskite performance due to molecular defects,and demonstrate an effective defect passivation strategy to obtain highly efficient and stable perovskite solar cells.展开更多
In this paper,we establish the stable results for a system of simultaneous general-ized vector quasi-equilibrium problems(SSGVQEP)by using its bounded rationality model.Under the abstract frame,a unified well-posednes...In this paper,we establish the stable results for a system of simultaneous general-ized vector quasi-equilibrium problems(SSGVQEP)by using its bounded rationality model.Under the abstract frame,a unified well-posedness on Hadamard types and Tikhonov types well-posedness for SSGVQEP is introduced.Moreover,sufficient condition for the well-posedness of SSGVQEP is given.Finally,we prove that the majority(in Baire category sense)of SSGVQEP is structural stability.展开更多
Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the...Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the formation energy,excess volume,dislocations and melting behaviors of GBs in CuFe alloys.It is illustrated that Fe solute affects the structural stability of Cu GBs substantially,the formation energy of GBs is reduced,but the thickness and melting point of GBs are increased,that is,the structural stability of Cu GBs is significantly improved owing to the Fe solutes.A strong scaling law exists between the formation energy,excess volume,thickness and melting point of GBs.Therefore,Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.展开更多
Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculate...Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculated lattice parameters were in good agreement with the experimental and literature values.The calculated heats of formation and cohesive energies shown that MgCu_(2)has the strongest alloying ability and structural stability.The elastic constants of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were calculated,the bulk moduli,shear moduli,Young's moduli and Poisson's ratio were derived.The calculated results shown that MgCu_(2),Mg_(2)Ca and MgZn_(2)are all ductile phases.Among the three phases,MgCu_(2)has the strongest stiffness and the plasticity of MgZn_(2)phase is the best.The density of states(DOS),Mulliken electron occupation number and charge density difference of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were discussed to analyze the mechanism of structural stability and mechanical properties.展开更多
The present paper continues the topic of our recent paper in the same journal,aiming to show the role of structural stability in financial modeling.In the context of financial market modeling,structural stability mean...The present paper continues the topic of our recent paper in the same journal,aiming to show the role of structural stability in financial modeling.In the context of financial market modeling,structural stability means that a specific“no-arbitrage”property is unaffected by small(with respect to the Pompeiu–Hausdorff metric)perturbations of the model’s dynamics.We formulate,based on our economic interpretation,a new requirement concerning“no arbitrage”properties,which we call the“uncertainty principle”.This principle in the case of no-trading constraints is equivalent to structural stability.We demonstrate that structural stability is essential for a correct model approximation(which is used in our numerical method for superhedging price computation).We also show that structural stability is important for the continuity of superhedging prices and discuss the sufficient conditions for this continuity.展开更多
A new structural configuration with better impact stability for increasing energy absorbing efficiency is found.Based on finite element analysis,deformation modes of double-hat structure under axial impact loading are...A new structural configuration with better impact stability for increasing energy absorbing efficiency is found.Based on finite element analysis,deformation modes of double-hat structure under axial impact loading are categorized to find the main reasons that affect deformation stability.It is revealed that,in a double-hat structure,the location of the flanges is highly related to the deformation mode and energy absorbing efficiency.Moving the flanges away from their traditional mid-location may result in more regular and stable deformation mode and achieve higher energy absorbing efficiency.The flange offset value needs to be controlled within a certain range,otherwise,the double-hat structure would tend to deform like a top-hat structure and the energy absorbing efficiency could be compromised.These findings and analyses lead to a new structural design configuration-asymmetric flange locations-for enhancing the deformation mode stability in double-hat structures.展开更多
SrLi_(2)Ti_(6)O_(14)(SLTO)coated with different amount of ZrO_(2)was successfully prepared.The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity.Furthermo...SrLi_(2)Ti_(6)O_(14)(SLTO)coated with different amount of ZrO_(2)was successfully prepared.The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity.Furthermore,ZrO_(2)coating not only enhances the structural stability of the materials but also facilitates the diffusion of lithium through the SEI film.As a result,the redox polarization was reduced,and the reversibility of the electrochemical reaction was enhanced.Particularly,SLTO-ZrO_(2)-2 sample delivers a high initial lithiation capacity of 283.6 mA h g^(-1),and the values maintain at 251.7,228.0,207.4,175.3,and 147.7 mA h g^(-1)at the current densities of 0.13,0.26,0.54,1.31,and 2.62 A g^(-1),respectively.Our experiment also confirmed that SLTO materials coated with ZrO_(2)are suitable for high power density applications,and the lithiation specific energy efficiency of SLTO-ZrO_(2)-2 is 200%as high as that of pure SLTO at a power density of 1257 W kg^(-1).展开更多
The strict definition and logical description of the concept of structure stability and failure are presented. The criterion of structure stability is developed based on plastic complementary energy and its variation....The strict definition and logical description of the concept of structure stability and failure are presented. The criterion of structure stability is developed based on plastic complementary energy and its variation. It is presented that the principle of minimum plastic complementary energy is the combination of structure equilibrium, coordination condition of deformation and constitutive relationship. Based on the above arguments, the deformation reinforcement theory is developed. The structure global stability can be described by the relationship between the global degree of safety of structure and the plastic complementary energy. Correspondingly, the new idea is used in the evaluations of global stability, anchorage force of dam-toe, fracture of dam-heel and treatment of faults of high arch dams in China. The results show that the deformation reinforcement theory provides a uniform and practical theoretical framework and a valuable solution for the analysis of global stability, dam-heel cracking, dam-toe anchorage and reinforcement of faults of high arch dams and their foundations.展开更多
Co-free Li-rich layered oxide cathodes have drawn much attention owing to their low cost and high energy density.Nevertheless,anion oxidation of oxygen leads to oxygen peroxidation during the first charging process,wh...Co-free Li-rich layered oxide cathodes have drawn much attention owing to their low cost and high energy density.Nevertheless,anion oxidation of oxygen leads to oxygen peroxidation during the first charging process,which leads to co-migration of transition metal ions and oxygen vacancies,causing structural instability.In this work,we propose a pre-activation strategy driven by chemical impregnation to modulate the chemical state of surface lattice oxygen,thus regulating the structural and electrochemical properties of the cathodes.In-situ X-ray diffraction confirms that materials based on activated oxygen configuration have higher structural stability.More importantly,this novel efficient strategy endows the cathodes having a lower surface charge transfer barrier and higher Li+transfer kinetics characteristic and ameliorates its inherent issues.The optimized cathode exhibits excellent electrochemical performance:after 300 cycles,high capacity(from 238 m Ah g^(-1)to 193 m Ah g^(-1)at 1 C)and low voltage attenuation(168 mV)are obtained.Overall,this modulated surface lattice oxygen strategy improves the electrochemical activity and structural stability,providing an innovative idea to obtain high-capacity Co-free Li-rich cathodes for next-generation Li-ion batteries.展开更多
The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coh...The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coherent feature. Its orientation relationship is (020)γ／／(220)TiC, [001]γ||[001]TiC. During the aging at 1473 K, the TiC/γ interface may dissolve in matrix and lamellar M23C6 compound may precipitate from γ-matrix.展开更多
Silicon(Si)anode has been considered a promising candidate due to its remarkable theoretical capacity but it was plagued by severe pulverization because of the inherent huge volume variation.Enhancing electrode stabil...Silicon(Si)anode has been considered a promising candidate due to its remarkable theoretical capacity but it was plagued by severe pulverization because of the inherent huge volume variation.Enhancing electrode stability is an effective approach to improve electrochemical performance.Herein,a stable Si anode was established by an innovative construction of the bonding between conductive agents and active materials/binders.As a result,the strong interaction of electrode components not only effectively alleviates the volume expansion of Si but also achieves a stable interface by generating the beneficial solid electrolyte interphase(SEI)composition.Attributed to the deliberate scheme of the electrode,the Si anode exhibits sterling electrochemical performance.Besides,the device of the electrode is not only effective for other binders but also for other anode materials with high volume variation,thus shedding light on the rational design of electrodes for high-energy-density lithium-ion batteries.展开更多
基金National Natural Science Foundation of China (No. 10602028)Student Research Train Program of BeiHang University
文摘We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.
文摘In ordinary differential equations, structural stability of hyperbolic fixed points is a classical result, but the proof of this result in [2] has same small mistake. In this paper,we will correct the above mistake by using the Hartman theorem and its idea.
文摘The reliable functioning of ion channels should be closely related to their structural stability. The selectivity filter in the KcsA potassium channel possesses four stable ion binding sites that can coordinate nearly fully dehydrated ions, whereas only two of such binding sites exist in the non-selective NaK channel, and none of them is found in the NavAb sodium channel. Here we show that the stability of the selectivity filters in these tetrameric cation channels is inversely correlated with the number of stable binding sites by extensive molecular dynamics simulations. While the presence of coordinated ions is crucial for the selectivity filters of the KcsA and NaK channels to stabilize the conformations in their crystal structures, the selectivity filter of the NavAb channel shows higher stability, independent of the presence of ions. We further show that the distinct repulsive electrostatic interactions between negatively charged oxygen atoms in the selectivity filter which form the stable binding sites are responsible for the different stability of these cation channels. The hydrogen bonding networks between residues in the selectivity filter and its adjacent pore helix also play an important role in maintaining stability. Together, these results provide important mechanistic insights into the structural stability of the selectivity filters in typical cation channels.
文摘Degradation of the physical quality of the soil is a common problem encountered in agrosystems, particularly in the case of open field cropping systems in the northern areas of Côte d’Ivoire. Thus, the structural stability of the soil, which is a good indicator of the sensitivity to threshing and to water erosion in relation to the accumulation of organic matter, was evaluated in two types of soil (Ferralsol and Cambisol) in cashew orchards, in two villages (Mahana and Sanankoro) producing cashew nuts, located the Department of Touba in the North West of Côte d’Ivoire. The objective of this study is to develop new technical routes that are better suited to further promote the sequestration of organic carbon in the soil. Soil samples were taken from open soil profiles at the two chosen sites to allow laboratory analyzes. The results indicate that the surface horizon of Cambisol (site 1) is more stable (Is = 0.78) than that of Ferralsol (site 2;Is = 1.08) with nevertheless relatively small thicknesses of horizons. The median horizons and those of depth, indicate a mediocre stability (Is vary from 1.03 to 1.62). In terms of the quantity of organic carbon, the estimated values vary from 1.96 to 4.53 t⋅ha−1 for Cambisol (site 1) and from 1.44 to 3.46 t⋅ha−1 for Ferralsol (site 2). These values remain relatively low especially at the level of the median horizons and those located in depths. Statistical tests have shown a very highly significant and negative association between the structural stability of soils and the amount of organic carbon in the different horizons. The relationship implies that organic carbon plays an important role in the structural stability of soil horizons under cashew tree orchards.
基金This work was supported by the National Natural Science Foundation of China(22125106,22101181 and 22101184)the Guangdong Province"Pearl River Talents Plan"Innovative and Entrepreneurial Teams Project(2021ZT09C289)the Developmental Fund for Science and Technology of Shenzhen(RCJC20200714114556036).
文摘Metallo-supramolecular architectures that are constructed by coordination-driven self-assembly have received tremendous attention on account of their diverse yet molecular-level precise structures and broad applications.Of particular,metal cations and counter anions are fundamentally important in terms of self-assembly,characterization and property;however,their effects on the structural stabilities of metallo-supramolecular architectures have seldom been investigated.To address this issue,herein,a series of octahedral metallo-cages that are capable of tolerating with five metal cations(Pd^(2+),Cu^(2+),Ni^(2+),Co^(2+)and Zn^(2+)),and five counter anions(ClO_(4)^(–),OTf^(–),BF_(4)^(–),NTf_(2)^(–)and NO_(3)^(–))are constructed by the coordination-driven self-assembly of a well-designed tritopic isoquinoline-based ligand with corresponding metal salts.Structural stability studies show that metal cations and counter anions play a critical role in the stability of the resulting cages depending on their coordination abilities and stacking manners.This work provides deep insights in the ever-diversifying field of metallo-supramolecular chemistry,and will enable us to design more sophisticated assembled structure with desired function.
基金This work was supported by the National Natural Science Foundation of China(Nos.52172069 and 51950410596)the Key R&D Plan of Jiangsu Province(No.BE2019094)+1 种基金Qing Lan Project of Jiangsu Province(No.[2016]15)Innovation/Entrepreneurship Program of Jiangsu Province(No.JSSCTD202146).
文摘Two-dimensional nanomaterials(2DNMs)have attracted significant research interest due to their outstanding structural properties,which include unique electrical nanostructures,large surface areas,and high surface reactivity.These adaptable materials have outstanding physicochemical characteristics,making them useful in a variety of applications such as gas-sensing,electronics,energy storage,and catalysis.Extensive research has been conducted in the pursuit of high performance room-temperature(RT)gas sensors with good selectivity,high sensitivity,long-term stability,and rapid response/recovery kinetics.Metal oxides,transition metal chalcogenides,MXenes,graphene,phosphorene,and boron nitride have all been discovered as 2DNMs with strong potential for gas sensors.This review presents an in-depth analysis of current advances in 2DNM research.It includes synthetic techniques,structural stabilities,gas-sensing mechanisms,critical performance parameters,and factors influencing gas-sensing capabilities of 2DNMs.Furthermore,the present study emphasizes structural engineering and optimization methodologies that improve gas-sensing performance.It also highlights current challenges and outlines future research directions in the domain of tailoring 2DNMs for advanced RT gas sensors.This systematically designed comprehensive review article aims to provide readers with profound insights into gas detection,thereby inspiring the generation of innovative ideas to develop cutting-edge 2DNMs-based gas sensors.
基金This work was supported by the National Natural Science Foundation of China(No.51372136)the NSFC-Guangdong united fund(U1401246).
文摘Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution content,P element completely enters into the lattice,forms[PO_(4)]tetrahedrons and partially replaces[SiO_(4)]tetrahedrons,which is confirmed by X-ray diffraction and X-ray photoelectron spectroscope measurements.Phosphorus substitution helps to suppress the change of coordination number of Mn and stabilize the material structure to some extent,obtaining better electrochemical performance in the early cycle.With the increase of P content,parts of P element exist in Li_(3)PO_(4)which distributes uniformly and co-exists with active substance.Electrochemical tests prove that existing Li_(3)PO_(4)has positive impacts on cycle and rate performance,and the lithium ion diffusion coefficient increases by about 14 times than pristine sample.Under the synergistic effects of phosphate substation and proper Li_(3)PO_(4),Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C shows enhanced electrochemical performances.
基金the National Natural Science Foundation of China(No.50571035)the National High Technology Research and Development Project(863) of China(No.2006AA032528)
文摘The energetic and electronic structures of precipitates on the Cu-rich side of Cu-Ni-Si alloys were investigated by using the first-principle calculations based on plane-wave pseudopotential method.The negative formation heats and the cohesive energies of these precipitates were estimated with electronic structure calculations, and their structural stability was also analyzed.The results show thatδ-Ni2Si,γ-Ni5Si2 andβ-Ni3Si precipitates all have great alloying ability and structural stability,which,after comparing their density of states （DOS）,is found attributed to the pseudogap effect near the Fermi level（Ef）and strong hybridization between the Ni-3d and Si-3p states.Compared with the other two precipitates,theδ-Ni2Si precipitate has the greatest structural stability,which is resulted from its lower DOS at Ef and the main bonding peaks slightly moving to the low energy region.
基金This work was supported by the Beijing Natural Science Foundation(No.2212031)the National Natural Science Foundation of China(Nos.21973006,51861135101,and 21520102005)R.L.acknowledges the financial support by the Recruitment Program of Global Youth Experts of China and the Beijing Normal University Startup.O.V.P.acknowledges the support of the US Department of Energy(No.DE-SC0014429).
文摘Hybrid organic-inorganic perovskites are currently considered the most promising next-generation photovoltaic material.However,poor stability,arising from structural degradation under exposure to moisture,heat,and strong current,remains a critical challenge for their device applications.Using ab initio nonadiabatic molecular dynamics,we demonstrate that methylamine fragments deriving from the dissociation of the methylammonium cation can undermine structural stability,produce deep hole traps,and decrease charge carrier lifetimes by 1-3 orders of magnitude.Both stability and charge lifetime can be restored by methylamine passivation with chlorines,which withdraw electrons from the lone electron pair of methylamine and bring the trap levels down into the valence band.The charge lifetime of the passivated system is even longer than that of the pristine perovskite.The simulations reveal the detailed microscopic mechanism underlying deterioration of perovskite performance due to molecular defects,and demonstrate an effective defect passivation strategy to obtain highly efficient and stable perovskite solar cells.
基金This research was supported by the National Natural Science Foundation of China(Nos.11761023 and 11561013)Support Plan for Science and Technology Top-notch Talents of Guizhou Higher Education Institutions(No.2017[081])+1 种基金Natural Science Foundation of Guizhou Normal College(No.2017BS009)Natural Science Foundation of Guizhou Province(Nos.[2017]5788,LH[2017]7723 and[2016]5609).
文摘In this paper,we establish the stable results for a system of simultaneous general-ized vector quasi-equilibrium problems(SSGVQEP)by using its bounded rationality model.Under the abstract frame,a unified well-posedness on Hadamard types and Tikhonov types well-posedness for SSGVQEP is introduced.Moreover,sufficient condition for the well-posedness of SSGVQEP is given.Finally,we prove that the majority(in Baire category sense)of SSGVQEP is structural stability.
基金supported by National Key Research and Development Program of China(No.2021YFB3400800)National Natural Science Foundation of China(Grant No.52271136,51901177)Natural Science Foundation of Shaanxi Province(No.2021JC-06,2019TD-020).
文摘Grain boundaries(GBs)play a crucial role on the structural stability and mechanical properties of Cu and its alloys.In this work,molecular dynamics(MD)simulations are employed to study the effects of Fe solutes on the formation energy,excess volume,dislocations and melting behaviors of GBs in CuFe alloys.It is illustrated that Fe solute affects the structural stability of Cu GBs substantially,the formation energy of GBs is reduced,but the thickness and melting point of GBs are increased,that is,the structural stability of Cu GBs is significantly improved owing to the Fe solutes.A strong scaling law exists between the formation energy,excess volume,thickness and melting point of GBs.Therefore,Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.
基金This work is supported by National Key Technology Research and Development Program of Ministry of Science and Technology of China(2011BAE22B00)Program for Liaoning Innovative Research Team in University.
文摘Electronic structure and elastic properties of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were investigated by means of first-principles calculations from CASTEP program based on density functional theory(DFT).The calculated lattice parameters were in good agreement with the experimental and literature values.The calculated heats of formation and cohesive energies shown that MgCu_(2)has the strongest alloying ability and structural stability.The elastic constants of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were calculated,the bulk moduli,shear moduli,Young's moduli and Poisson's ratio were derived.The calculated results shown that MgCu_(2),Mg_(2)Ca and MgZn_(2)are all ductile phases.Among the three phases,MgCu_(2)has the strongest stiffness and the plasticity of MgZn_(2)phase is the best.The density of states(DOS),Mulliken electron occupation number and charge density difference of MgCu_(2),Mg_(2)Ca and MgZn_(2)phases were discussed to analyze the mechanism of structural stability and mechanical properties.
文摘The present paper continues the topic of our recent paper in the same journal,aiming to show the role of structural stability in financial modeling.In the context of financial market modeling,structural stability means that a specific“no-arbitrage”property is unaffected by small(with respect to the Pompeiu–Hausdorff metric)perturbations of the model’s dynamics.We formulate,based on our economic interpretation,a new requirement concerning“no arbitrage”properties,which we call the“uncertainty principle”.This principle in the case of no-trading constraints is equivalent to structural stability.We demonstrate that structural stability is essential for a correct model approximation(which is used in our numerical method for superhedging price computation).We also show that structural stability is important for the continuity of superhedging prices and discuss the sufficient conditions for this continuity.
基金Supported by US-China CERC on Clean Vehicle Consortium,the Ministry of Science and Technology of China(2010DFA72760)
文摘A new structural configuration with better impact stability for increasing energy absorbing efficiency is found.Based on finite element analysis,deformation modes of double-hat structure under axial impact loading are categorized to find the main reasons that affect deformation stability.It is revealed that,in a double-hat structure,the location of the flanges is highly related to the deformation mode and energy absorbing efficiency.Moving the flanges away from their traditional mid-location may result in more regular and stable deformation mode and achieve higher energy absorbing efficiency.The flange offset value needs to be controlled within a certain range,otherwise,the double-hat structure would tend to deform like a top-hat structure and the energy absorbing efficiency could be compromised.These findings and analyses lead to a new structural design configuration-asymmetric flange locations-for enhancing the deformation mode stability in double-hat structures.
基金financially supported by the National Natural Science Foundation of China(nos.21773060,51774002,and 21601054)Fundamental Research Funds for the Central Universities(no.N182304014)+1 种基金Youth Innovation Team Project of Science and technology of Heilongjiang University(2018-KYYWF-1593)Young Scholar Project of the Long Jiang Scholars Program(Q201818)
文摘SrLi_(2)Ti_(6)O_(14)(SLTO)coated with different amount of ZrO_(2)was successfully prepared.The as-obtained composites are stacked by a series of particles with a pure phase structure and a good crystallinity.Furthermore,ZrO_(2)coating not only enhances the structural stability of the materials but also facilitates the diffusion of lithium through the SEI film.As a result,the redox polarization was reduced,and the reversibility of the electrochemical reaction was enhanced.Particularly,SLTO-ZrO_(2)-2 sample delivers a high initial lithiation capacity of 283.6 mA h g^(-1),and the values maintain at 251.7,228.0,207.4,175.3,and 147.7 mA h g^(-1)at the current densities of 0.13,0.26,0.54,1.31,and 2.62 A g^(-1),respectively.Our experiment also confirmed that SLTO materials coated with ZrO_(2)are suitable for high power density applications,and the lithiation specific energy efficiency of SLTO-ZrO_(2)-2 is 200%as high as that of pure SLTO at a power density of 1257 W kg^(-1).
基金Supported by the China National Funds for Distinguished Young Scientists (50925931)the Special Funds for Major State Basic Research Projects (2009CB724604)
文摘The strict definition and logical description of the concept of structure stability and failure are presented. The criterion of structure stability is developed based on plastic complementary energy and its variation. It is presented that the principle of minimum plastic complementary energy is the combination of structure equilibrium, coordination condition of deformation and constitutive relationship. Based on the above arguments, the deformation reinforcement theory is developed. The structure global stability can be described by the relationship between the global degree of safety of structure and the plastic complementary energy. Correspondingly, the new idea is used in the evaluations of global stability, anchorage force of dam-toe, fracture of dam-heel and treatment of faults of high arch dams in China. The results show that the deformation reinforcement theory provides a uniform and practical theoretical framework and a valuable solution for the analysis of global stability, dam-heel cracking, dam-toe anchorage and reinforcement of faults of high arch dams and their foundations.
基金the National Natural Science Foundation of China(51902072 and 22075062)the Heilongjiang Touyan Team(HITTY-20190033)+2 种基金the Heilongjiang Province“hundred million”project science and technology major special projects(2019ZX09A02)the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Technology No.2020DX11)the Fundamental Research Funds for the Central Universities(FRFCU5710051922)。
文摘Co-free Li-rich layered oxide cathodes have drawn much attention owing to their low cost and high energy density.Nevertheless,anion oxidation of oxygen leads to oxygen peroxidation during the first charging process,which leads to co-migration of transition metal ions and oxygen vacancies,causing structural instability.In this work,we propose a pre-activation strategy driven by chemical impregnation to modulate the chemical state of surface lattice oxygen,thus regulating the structural and electrochemical properties of the cathodes.In-situ X-ray diffraction confirms that materials based on activated oxygen configuration have higher structural stability.More importantly,this novel efficient strategy endows the cathodes having a lower surface charge transfer barrier and higher Li+transfer kinetics characteristic and ameliorates its inherent issues.The optimized cathode exhibits excellent electrochemical performance:after 300 cycles,high capacity(from 238 m Ah g^(-1)to 193 m Ah g^(-1)at 1 C)and low voltage attenuation(168 mV)are obtained.Overall,this modulated surface lattice oxygen strategy improves the electrochemical activity and structural stability,providing an innovative idea to obtain high-capacity Co-free Li-rich cathodes for next-generation Li-ion batteries.
文摘The morphology. orientation relationship and stability of TiC/γ interface in Fe-Cr-Ni base composite synthesized with a liquid state in-situ process have been studied. The TiC/γ interface in as-cast sample is of coherent feature. Its orientation relationship is (020)γ／／(220)TiC, [001]γ||[001]TiC. During the aging at 1473 K, the TiC/γ interface may dissolve in matrix and lamellar M23C6 compound may precipitate from γ-matrix.
基金the National Natural Science Foundation of China(51874108,52164036,52264046)the Guizhou High Level and Innovative Talents Projects([2022]009-1)+1 种基金the Guizhou Science and Technology Planning Project([2020]5021)the Natural Science Research Project of Guizhou Provincial Department of Education([2022]041)。
文摘Silicon(Si)anode has been considered a promising candidate due to its remarkable theoretical capacity but it was plagued by severe pulverization because of the inherent huge volume variation.Enhancing electrode stability is an effective approach to improve electrochemical performance.Herein,a stable Si anode was established by an innovative construction of the bonding between conductive agents and active materials/binders.As a result,the strong interaction of electrode components not only effectively alleviates the volume expansion of Si but also achieves a stable interface by generating the beneficial solid electrolyte interphase(SEI)composition.Attributed to the deliberate scheme of the electrode,the Si anode exhibits sterling electrochemical performance.Besides,the device of the electrode is not only effective for other binders but also for other anode materials with high volume variation,thus shedding light on the rational design of electrodes for high-energy-density lithium-ion batteries.
