Metal oxides as support for constructing precious metal single-atom catalysts hold great promise for a wide range of industrial applications,but achieving a high-loading of thermally stable metal single atoms on such ...Metal oxides as support for constructing precious metal single-atom catalysts hold great promise for a wide range of industrial applications,but achieving a high-loading of thermally stable metal single atoms on such supports has been challenging.Herein,we report an innovative strategy for the fabrication of high-density single-atoms(Rh,Ru,Pd)catalysts on CaAl-layered double hydroxides(CaAl-LDH)via isomorphous substitution.The Rh species have occupied Ca^(2+)vacancies within CaAl-LDH laminate by ion-exchange,facilitating a substantial loading of isolated Rh single-atoms.Such catalysts displayed superior performance in the selective hydrogenation to quinoline,pivotal for liquid organic hydrogen storage,and the universality for the hydrogenation of N-heterocyclic aromatic hydrocarbons was also verified.Combining the experimental results and density functional theory calculations,the pathway of quinoline hydrogenation over Rh1CaAl-LDH was proposed.This synthetic strategy marks a significant advancement in the field of single-atom catalysts,expanding their horizons in green chemical processes.展开更多
The substitutions of Ti, Fe and Zr into zeolite Y in the aqueous solutions of (NH4)2TiF6, (NH4)3ZrF7 and (NH4)3FeF6 were systematically Investigated. It was found that Ai atoms in the framework can be replaced by some...The substitutions of Ti, Fe and Zr into zeolite Y in the aqueous solutions of (NH4)2TiF6, (NH4)3ZrF7 and (NH4)3FeF6 were systematically Investigated. It was found that Ai atoms in the framework can be replaced by some metallic elements and the extent of substitution depends on the M/A1 ratio of the solution. The maximum allowable M/A1 ratio of the aqueous solution Is related with the radius of the M atom and the stability constant of the MFnm- complex. The substituted zeolite samples with crystallinity greater than 80% were characterized by means of XRD, IR, DTA, TPR and NH3-TPD measurements. The incorporation of Ti, Fe and Zr into the zeolite leads to an increase in the unit cell parameter, a lowering of thermal stability and a red shift of the asymmetric stretching frequency. The extent of these changes is apparently related with the ionic radius of the metallic element and the degree of substitution. The results of various characterization methods show that the het-eroatoms are readily Introduced into the zeolite framework by this preparation method. It was also observed that the substitution of heteroatoms may strengthen or weaken the surface acidity of zeolite Y.展开更多
In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some...In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some of the substituting cations, e.g. Cr3+, V3+ and Mn2+, improve the catalytic activity of magnetite in heterogeneous Fenton reaction through the enhancement of hydroxyl radical OH production and the pollutant adsorption.展开更多
The multiple endothermic peaks without observable recrystallization phenomenon of isomorphous poly(3-hydroxybutyrate-co-3-hydroxyvalerate)[P(HB-co-HV)]with the middle HV content of 19.4 mol%and 28.7 mol%were confirmed...The multiple endothermic peaks without observable recrystallization phenomenon of isomorphous poly(3-hydroxybutyrate-co-3-hydroxyvalerate)[P(HB-co-HV)]with the middle HV content of 19.4 mol%and 28.7 mol%were confirmed by differential scanning calorimetry(DSC),and the evolutions of crystal structure and lamellar morphology in the heating and melting process were tracked by in situ synchrotron wide angle X-ray diffraction(WAXD)and small angle X-ray scattering(SAXS)techniques.The emergence of asymmetric features of both the diffraction peaks and scattering curves indicates the coexistence of different lamellar crystals with varied unit cell parameters.Based on the in situ WAXD and SAXS measurements,we calculated the evolutions of the unit cell parameters a and b as well as the long period and lamellar thickness upon heating.The comparative analysis of WAXD and SAXS data confirms that the multiple endothermic peaks of P(HB-co-19.4%HV)and P(HB-co-28.7%HV)result from the melting of different lamellae rather than the melting/recrystallization.The thinner,unstable uniform lamellae with HV counits total inclusion melt first and the thicker,stable sandwich lamellae with HV counits partial inclusion melt last.In addition,the large second melting peak in P(H B-co-19.4%HV),differing from that of samples with HV content of 28.7 mol%and 36.2 mol%,is due to the unique state of HV content leading to a transition of sandwich lamellae to uniform lamellae.The present study establishes the relationship between the different lamellae structure and multiple melting behaviors of isomorphous copolymer.展开更多
An aluminium-substituted framework gallophosphate with occluded triethylamine was synthesized hydrothermally. 27Al MAS NMR spectroscopy indicates that only the tetrahedral coordinated gallium atoms in the gallophospha...An aluminium-substituted framework gallophosphate with occluded triethylamine was synthesized hydrothermally. 27Al MAS NMR spectroscopy indicates that only the tetrahedral coordinated gallium atoms in the gallophosphate are substituted by aluminium atoms. The substitution leads to an evident decrease in cell volume of the crystal. The differences between the original gallophosphate and the aluminium-substituted one are also found for the IR spectrum and the thermal property.展开更多
We analyze existence and uniqueness of solutions for perturbations of a Jensen functional inequality in several variables.Applications in connection with asymptotic behaviors of isomorphisms,derivations and n-Jordan d...We analyze existence and uniqueness of solutions for perturbations of a Jensen functional inequality in several variables.Applications in connection with asymptotic behaviors of isomorphisms,derivations and n-Jordan derivations on Banach algebras are also provided.The results of this paper correct and improve the main results of[12,16,22,23]and improve the corresponding results in[2,9,27],but under weaker assumptions.展开更多
Isomorphic substitution of ferric ion(Fe~(3+))by aluminum ion(Al~(3+))in iron(hydro)oxides is ubiquitous in natural environments.Aluminum substitution inevitably leads to changes in the microstructures,physicochemical...Isomorphic substitution of ferric ion(Fe~(3+))by aluminum ion(Al~(3+))in iron(hydro)oxides is ubiquitous in natural environments.Aluminum substitution inevitably leads to changes in the microstructures,physicochemical properties,and surface reactions of iron(hydro)oxides,which may have great impacts on the sequestration of nutrients and contaminants in soils and aquatic environments.Over the past decades,the structural properties and surface reactivity of Al-substituted iron(hydro)oxides have been intensively studied.Iron(hydro)oxides in various structural forms and with different Al substitution amounts present high application potentials in addressing environmental issues.A timely summary of the structural properties and interfacial reactions of the most common and representative Al-substituted iron(hydro)oxides is of significance.Herein,the effects of Al substitution on the structural properties and surface activities of iron(hydro)oxides were clarified according to the microstructure,crystal facets,surface site type and density,interfacial reaction mechanisms,and modeling parameters of iron(hydro)oxides.This review systematically elucidates how Al substitution affects the structural properties and surface reactions of iron(hydro)oxides,including the well crystallized goethite and hematite and the poorly crystallized ferrihydrite,providing theoretical guidance for further exploration of the mineralogical characteristics and environmental geochemical behaviors of iron(hydro)oxides.展开更多
In open quantum systems,the Liouvillian gap characterizes the relaxation time toward the steady state.However,accurately computing this quantity is notoriously difficult due to the exponential growth of the Hilbert sp...In open quantum systems,the Liouvillian gap characterizes the relaxation time toward the steady state.However,accurately computing this quantity is notoriously difficult due to the exponential growth of the Hilbert space and the non-Hermitian nature of the Liouvillian superoperator.In this work,we propose a variational quantum algorithm for efficiently estimating the Liouvillian gap.By utilizing the Choi-Jamio lkowski isomorphism,we reformulate the problem as finding the first excitation energy of an effective non-Hermitian Hamiltonian.Our method employs variance minimization with an orthogonality constraint to locate the first excited state and adopts a two-stage optimization scheme to enhance convergence.Moreover,to address scenarios with degenerate steady states,we introduce an iterative energy-offset scanning technique.Numerical simulations on the dissipative XXZ model confirm the accuracy and robustness of our algorithm across a range of system sizes and dissipation strengths.These results demonstrate the promise of variational quantum algorithms for simulating open quantum many-body systems on near-term quantum hardware.展开更多
Let M and N be two factor von Neumann algebras that their dimensions are large than 1,η≠-1 a non zero complex number and Φa(not necessary linear)bijection between two factor von Neumann algebras satisfying Φ(I)=I....Let M and N be two factor von Neumann algebras that their dimensions are large than 1,η≠-1 a non zero complex number and Φa(not necessary linear)bijection between two factor von Neumann algebras satisfying Φ(I)=I.For all A,B∈M,define by A■B=AB+BA the Jordan product of A and B,A·_(η)B=AB+ηBA^(*)the Jordan η-*-product of A and B,respectively.Let Φ and Φ^(-1)preserve the mixed Jordan triple η-*-products.It is proved that Φ is a linear *-isomorphism if η is not real and Φ is the sum of a linear *-isomorphism and a conjugate linear *-isomorphism if η is real.展开更多
KTiOPO-4(KTP) crystal is a nonlinear optical material with superior properties. The KTP structure, point group mm2, is typified by the chemical form {K++}〔Ti 4+〕O(P 5+)O-4, where the curly brackets indicate nine or ...KTiOPO-4(KTP) crystal is a nonlinear optical material with superior properties. The KTP structure, point group mm2, is typified by the chemical form {K++}〔Ti 4+〕O(P 5+)O-4, where the curly brackets indicate nine or eightfold coordination, the square brackets sixfold octahedral coordination and the parentheses fourfold tetrahedral coordination. Different isovalent and aliovalent substitutions in a given structure is quite interesting. The KTP-type structure is extremely accommodating with respect to partial or complete isomorphous substitution which may be especially significant in optical devices such as waveguides. A monographic review of the structure-property relationship of KTP isomorphous substitution is briefly and precisely presented. It is shown that the properties of KTP are very sensitive to its structure. Among the composition, structure and properties of KTP-type crystal, the structure is the core because it is a link between the composition and properties.展开更多
The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite wa...The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity（WHSV） of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.展开更多
The article is devoted to proving the inconsistency of set theory arising from the existence of strange trees. All steps of the proof rely on common informal set-theoretic reasoning, but they take into account the pro...The article is devoted to proving the inconsistency of set theory arising from the existence of strange trees. All steps of the proof rely on common informal set-theoretic reasoning, but they take into account the prohibitions that were introduced into axiomatic set theories in order to overcome the difficulties encountered by the naive Cantor set theory. Therefore, in fact, the article is about proving the inconsistency of existing axiomatic set theories, in particular, the ZFC theory.展开更多
The article is devoted to completing the proof of the inconsistency of set theory. In this article and in the two preceding ones, all steps of the proof are based on generally accepted informal set-theoretic reasoning...The article is devoted to completing the proof of the inconsistency of set theory. In this article and in the two preceding ones, all steps of the proof are based on generally accepted informal set-theoretic reasoning, but consider the prohibitions that were included in axiomatic set theories in order to overcome the difficulties encountered by the naive Cantor set theory. Therefore, in fact, the articles are about proving the inconsistency of existing axiomatic set theories, in particular, the ZFC theory.展开更多
Nanosized Ga-containing ZSM-5 zeolites were prepared via isomorphous substitution and impregnation followed by characterized using various techniques. The catalytic performance of the zeolites for the aromatization of...Nanosized Ga-containing ZSM-5 zeolites were prepared via isomorphous substitution and impregnation followed by characterized using various techniques. The catalytic performance of the zeolites for the aromatization of 1-hexene was investigated. The results indicate that isomorphous substitution promotes the incorporation of Ga heteroatoms into the framework along with the formation of extra-framework GaO;species（[GaO;]a） that have stronger interactions with the negative potential of the framework. In addition, based on the Py-IR results and catalytic performance, the [GaO;]aspecies with stronger Lewis acid sites produced a better synergism with moderate Br?nsted acid sites and thus improved the selectivity to aromatic compounds. However, the impregnation results in the formation of Ga;O;phase and small amounts of GaO;species that are mainly located on the external surface（[GaO;];）, which contribute to weaker Lewis acid sites due to weaker interactions with the zeolite framework. During 1-hexene aromatization, the nanosized Ga isomorphously substituted ZSM-5 zeolite samples（Gax-NZ5） exhibited better catalytic performance compared to the impregnated samples, and the highest aromatic yield（i.e.,65.4 wt%） was achieved over the Ga4.2-NZ5 sample, which contained with the highest Ga content.展开更多
In order to improve the accuracy and integrality of mining data records from the web, the concepts of isomorphic page and directory page and three algorithms are proposed. An isomorphic web page is a set of web pages ...In order to improve the accuracy and integrality of mining data records from the web, the concepts of isomorphic page and directory page and three algorithms are proposed. An isomorphic web page is a set of web pages that have uniform structure, only differing in main information. A web page which contains many links that link to isomorphic web pages is called a directory page. Algorithm 1 can find directory web pages in a web using adjacent links similar analysis method. It first sorts the link, and then counts the links in each directory. If the count is greater than a given valve then finds the similar sub-page links in the directory and gives the results. A function for an isomorphic web page judgment is also proposed. Algorithm 2 can mine data records from an isomorphic page using a noise information filter. It is based on the fact that the noise information is the same in two isomorphic pages, only the main information is different. Algorithm 3 can mine data records from an entire website using the technology of spider. The experiment shows that the proposed algorithms can mine data records more intactly than the existing algorithms. Mining data records from isomorphic pages is an efficient method.展开更多
The linear operations of the equivalent classes of crossed modules of Lie color algebras are studied. The set of the equivalent classes of crossed modules is proved to be a vector space, which is isomorphic with the h...The linear operations of the equivalent classes of crossed modules of Lie color algebras are studied. The set of the equivalent classes of crossed modules is proved to be a vector space, which is isomorphic with the homogeneous components of degree zero of the third cohomology group of Lie color algebras. As an application of this theory, the crossed modules of Witt type Lie color algebras is described, and the result is proved that there is only one equivalent class of the crossed modules of Witt type Lie color algebras when the abelian group Г is equal to Г＋. Finally, for a Witt type Lie color algebra, the classification of its crossed modules is obtained by the isomorphism between the third cohomology group and the crossed modules.展开更多
In this paper, the character matrix x n is studied, fast construction method of matrix X 2m is provided. And it is proved that the lower bound estimate of the number of an Latin squares matrix D[X m] is2m(2m)!+...In this paper, the character matrix x n is studied, fast construction method of matrix X 2m is provided. And it is proved that the lower bound estimate of the number of an Latin squares matrix D[X m] is2m(2m)!+∑mi=2[(2m)!] 2∏ij=1K j!∏rj=1b j!.展开更多
To achieve de novo protein structure determination of challenging cases, multi-wavelength anomalous diffraction(MAD) and multiple isomorphous replacement(MIR) phasing can be powerful tools to obtain low-resolution ini...To achieve de novo protein structure determination of challenging cases, multi-wavelength anomalous diffraction(MAD) and multiple isomorphous replacement(MIR) phasing can be powerful tools to obtain low-resolution initial phases from heavy-atom derivative datasets, then phase extension is needed against high-resolution data to obtain accurate structures.In this context, we propose a direct-methods procedure here that could improve the initial low-resolution MAD/MIR phase quality.And accordingly, an automated process for extending initial phases to high resolution is also described.These two procedures are both implanted in the newly released IPCAS pipeline.Three cases are used to perform the test, including one set of 4.17 ? MAD data from a membrane protein and two sets of MAD/MIR data with derivatives truncated down to 6.80 ? and 6.90 ?, respectively.All the results have shown that the initial phases generated from the direct-methods procedure are better than that from the conventional MAD/MIR methods.The automated phase extensions for the latter two cases starting from 6.80 ? to 3.00 ? and 6.90 ? to 2.80 ? are proved to be successful, leading to complete models.This may provide convenient and reliable tools for phase improvement and phase extension in difficult low-resolution tasks.展开更多
Solvothermal reaction of lanthanide（Ⅲ） salts with fluorescein （2-（6-hydroxy3-oxo-3H-xanthen-9-yl）benzoic acid） led to a series of new coordination polymers {[Ln（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·...Solvothermal reaction of lanthanide（Ⅲ） salts with fluorescein （2-（6-hydroxy3-oxo-3H-xanthen-9-yl）benzoic acid） led to a series of new coordination polymers {[Ln（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·DMF} n （Ln=Er,Eu,Gd,Tb,Tm,Yb）.The PXRD patterns of the complexes indicate they are isomorphous.The structure of complex {[Er（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·DMF} n has been determined by single-crystal X-ray diffraction,revealing a 2D framework in which DMF molecules were filled between the layers.The crystal structure belongs to the triclinic system,space group P1,with a=12.107（4）,b=12.232（4）,c=13.273（4）,α=68.005（7）,β=88.024（11）,γ=77.451（8）°,V=1776.7（9） 3,Z=2,D c=1.720 g/cm 3,μ=2.434 mm-1,F（000）=918,R int=0.0584,T=293（2） K,the final R=0.0621 and wR=0.1501.展开更多
A sufficient condition is given to assert that a continuous mapping between Rm and Rn has a zero. The constructive proof of the result is based upon continuation methods and supplies the existence of a path leading to...A sufficient condition is given to assert that a continuous mapping between Rm and Rn has a zero. The constructive proof of the result is based upon continuation methods and supplies the existence of a path leading to the zero point.展开更多
文摘Metal oxides as support for constructing precious metal single-atom catalysts hold great promise for a wide range of industrial applications,but achieving a high-loading of thermally stable metal single atoms on such supports has been challenging.Herein,we report an innovative strategy for the fabrication of high-density single-atoms(Rh,Ru,Pd)catalysts on CaAl-layered double hydroxides(CaAl-LDH)via isomorphous substitution.The Rh species have occupied Ca^(2+)vacancies within CaAl-LDH laminate by ion-exchange,facilitating a substantial loading of isolated Rh single-atoms.Such catalysts displayed superior performance in the selective hydrogenation to quinoline,pivotal for liquid organic hydrogen storage,and the universality for the hydrogenation of N-heterocyclic aromatic hydrocarbons was also verified.Combining the experimental results and density functional theory calculations,the pathway of quinoline hydrogenation over Rh1CaAl-LDH was proposed.This synthetic strategy marks a significant advancement in the field of single-atom catalysts,expanding their horizons in green chemical processes.
文摘The substitutions of Ti, Fe and Zr into zeolite Y in the aqueous solutions of (NH4)2TiF6, (NH4)3ZrF7 and (NH4)3FeF6 were systematically Investigated. It was found that Ai atoms in the framework can be replaced by some metallic elements and the extent of substitution depends on the M/A1 ratio of the solution. The maximum allowable M/A1 ratio of the aqueous solution Is related with the radius of the M atom and the stability constant of the MFnm- complex. The substituted zeolite samples with crystallinity greater than 80% were characterized by means of XRD, IR, DTA, TPR and NH3-TPD measurements. The incorporation of Ti, Fe and Zr into the zeolite leads to an increase in the unit cell parameter, a lowering of thermal stability and a red shift of the asymmetric stretching frequency. The extent of these changes is apparently related with the ionic radius of the metallic element and the degree of substitution. The results of various characterization methods show that the het-eroatoms are readily Introduced into the zeolite framework by this preparation method. It was also observed that the substitution of heteroatoms may strengthen or weaken the surface acidity of zeolite Y.
文摘In nature, iron cations in magnetite are usually isomorphically substituted by divalent (Co, Ni, Zn, Cu, Mn, etc.), trivalent (Al, V, Cr, etc.) and tetravalent (Ti) cations while maintaining the spinel structure. Some of the substituting cations, e.g. Cr3+, V3+ and Mn2+, improve the catalytic activity of magnetite in heterogeneous Fenton reaction through the enhancement of hydroxyl radical OH production and the pollutant adsorption.
基金the National Natural Science Foundation of China(Nos.51973097 and 51773101).
文摘The multiple endothermic peaks without observable recrystallization phenomenon of isomorphous poly(3-hydroxybutyrate-co-3-hydroxyvalerate)[P(HB-co-HV)]with the middle HV content of 19.4 mol%and 28.7 mol%were confirmed by differential scanning calorimetry(DSC),and the evolutions of crystal structure and lamellar morphology in the heating and melting process were tracked by in situ synchrotron wide angle X-ray diffraction(WAXD)and small angle X-ray scattering(SAXS)techniques.The emergence of asymmetric features of both the diffraction peaks and scattering curves indicates the coexistence of different lamellar crystals with varied unit cell parameters.Based on the in situ WAXD and SAXS measurements,we calculated the evolutions of the unit cell parameters a and b as well as the long period and lamellar thickness upon heating.The comparative analysis of WAXD and SAXS data confirms that the multiple endothermic peaks of P(HB-co-19.4%HV)and P(HB-co-28.7%HV)result from the melting of different lamellae rather than the melting/recrystallization.The thinner,unstable uniform lamellae with HV counits total inclusion melt first and the thicker,stable sandwich lamellae with HV counits partial inclusion melt last.In addition,the large second melting peak in P(H B-co-19.4%HV),differing from that of samples with HV content of 28.7 mol%and 36.2 mol%,is due to the unique state of HV content leading to a transition of sandwich lamellae to uniform lamellae.The present study establishes the relationship between the different lamellae structure and multiple melting behaviors of isomorphous copolymer.
基金Supported by the National Natural Science Foundation of China
文摘An aluminium-substituted framework gallophosphate with occluded triethylamine was synthesized hydrothermally. 27Al MAS NMR spectroscopy indicates that only the tetrahedral coordinated gallium atoms in the gallophosphate are substituted by aluminium atoms. The substitution leads to an evident decrease in cell volume of the crystal. The differences between the original gallophosphate and the aluminium-substituted one are also found for the IR spectrum and the thermal property.
文摘We analyze existence and uniqueness of solutions for perturbations of a Jensen functional inequality in several variables.Applications in connection with asymptotic behaviors of isomorphisms,derivations and n-Jordan derivations on Banach algebras are also provided.The results of this paper correct and improve the main results of[12,16,22,23]and improve the corresponding results in[2,9,27],but under weaker assumptions.
基金financially supported by the National Natural Science Foundation of China(Nos.42207352,42007020,and 42007015)the Natural Science Fund for Excellent Young Scholars of Hainan Province,China(No.324YXQN421)。
文摘Isomorphic substitution of ferric ion(Fe~(3+))by aluminum ion(Al~(3+))in iron(hydro)oxides is ubiquitous in natural environments.Aluminum substitution inevitably leads to changes in the microstructures,physicochemical properties,and surface reactions of iron(hydro)oxides,which may have great impacts on the sequestration of nutrients and contaminants in soils and aquatic environments.Over the past decades,the structural properties and surface reactivity of Al-substituted iron(hydro)oxides have been intensively studied.Iron(hydro)oxides in various structural forms and with different Al substitution amounts present high application potentials in addressing environmental issues.A timely summary of the structural properties and interfacial reactions of the most common and representative Al-substituted iron(hydro)oxides is of significance.Herein,the effects of Al substitution on the structural properties and surface activities of iron(hydro)oxides were clarified according to the microstructure,crystal facets,surface site type and density,interfacial reaction mechanisms,and modeling parameters of iron(hydro)oxides.This review systematically elucidates how Al substitution affects the structural properties and surface reactions of iron(hydro)oxides,including the well crystallized goethite and hematite and the poorly crystallized ferrihydrite,providing theoretical guidance for further exploration of the mineralogical characteristics and environmental geochemical behaviors of iron(hydro)oxides.
基金supported by the National Natural Science Foundation of China(Grant Nos.12375013 and 12275090)the Guangdong Basic and Applied Basic Research Fund(Grant No.2023A1515011460)Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2200001)。
文摘In open quantum systems,the Liouvillian gap characterizes the relaxation time toward the steady state.However,accurately computing this quantity is notoriously difficult due to the exponential growth of the Hilbert space and the non-Hermitian nature of the Liouvillian superoperator.In this work,we propose a variational quantum algorithm for efficiently estimating the Liouvillian gap.By utilizing the Choi-Jamio lkowski isomorphism,we reformulate the problem as finding the first excitation energy of an effective non-Hermitian Hamiltonian.Our method employs variance minimization with an orthogonality constraint to locate the first excited state and adopts a two-stage optimization scheme to enhance convergence.Moreover,to address scenarios with degenerate steady states,we introduce an iterative energy-offset scanning technique.Numerical simulations on the dissipative XXZ model confirm the accuracy and robustness of our algorithm across a range of system sizes and dissipation strengths.These results demonstrate the promise of variational quantum algorithms for simulating open quantum many-body systems on near-term quantum hardware.
文摘Let M and N be two factor von Neumann algebras that their dimensions are large than 1,η≠-1 a non zero complex number and Φa(not necessary linear)bijection between two factor von Neumann algebras satisfying Φ(I)=I.For all A,B∈M,define by A■B=AB+BA the Jordan product of A and B,A·_(η)B=AB+ηBA^(*)the Jordan η-*-product of A and B,respectively.Let Φ and Φ^(-1)preserve the mixed Jordan triple η-*-products.It is proved that Φ is a linear *-isomorphism if η is not real and Φ is the sum of a linear *-isomorphism and a conjugate linear *-isomorphism if η is real.
文摘KTiOPO-4(KTP) crystal is a nonlinear optical material with superior properties. The KTP structure, point group mm2, is typified by the chemical form {K++}〔Ti 4+〕O(P 5+)O-4, where the curly brackets indicate nine or eightfold coordination, the square brackets sixfold octahedral coordination and the parentheses fourfold tetrahedral coordination. Different isovalent and aliovalent substitutions in a given structure is quite interesting. The KTP-type structure is extremely accommodating with respect to partial or complete isomorphous substitution which may be especially significant in optical devices such as waveguides. A monographic review of the structure-property relationship of KTP isomorphous substitution is briefly and precisely presented. It is shown that the properties of KTP are very sensitive to its structure. Among the composition, structure and properties of KTP-type crystal, the structure is the core because it is a link between the composition and properties.
基金Project(21276067)supported by the National Natural Science Foundation of China
文摘The promoting effect of introducing Zn into nano-ZSM-5 zeolites by conventional impregnation method and isomorphous substitution on the performance of 1-hexene aromatization was investigated. The nano-ZSM-5 zeolite was synthesized by a seed-induced method without organic templates. The Zn-modified nano-ZSM-5 zeolite catalysts, xZ n/HNZ5 and y Zn/Al-HNZ5, were prepared by the conventional impregnation method and isomorphous substitution, respectively. The structure, chemical composition and acidity of the catalysts were characterized by XRD, XRF, N2 adsorption, SEM, NH3-TPD and Py-IR, while the catalytic properties were evaluated at 480 °C and a weight hourly space velocity（WHSV） of 2.0 h-1 in the aromatization procedure of 1-hexene. Compared with xZ n/HNZ5, y Zn/Al-HNZ5 exhibited smaller particles and higher dispersion of Zn species, which led to greater intergranular mesopore and homogeneous acidity distribution. Experimental results indicated that the synergy effect between the Brnsted and Lewis acid sites of the isomorphously substituted nano-ZSM-5 zeolites could significantly increase aromatics yield and improve catalytic stability in the 1-hexene aromatization.
文摘The article is devoted to proving the inconsistency of set theory arising from the existence of strange trees. All steps of the proof rely on common informal set-theoretic reasoning, but they take into account the prohibitions that were introduced into axiomatic set theories in order to overcome the difficulties encountered by the naive Cantor set theory. Therefore, in fact, the article is about proving the inconsistency of existing axiomatic set theories, in particular, the ZFC theory.
文摘The article is devoted to completing the proof of the inconsistency of set theory. In this article and in the two preceding ones, all steps of the proof are based on generally accepted informal set-theoretic reasoning, but consider the prohibitions that were included in axiomatic set theories in order to overcome the difficulties encountered by the naive Cantor set theory. Therefore, in fact, the articles are about proving the inconsistency of existing axiomatic set theories, in particular, the ZFC theory.
基金supported by the National Natural Science Foundation of China(Nos.21276067 and 21676074)Programs of International S&T cooperation(No.2014DFR41110)
文摘Nanosized Ga-containing ZSM-5 zeolites were prepared via isomorphous substitution and impregnation followed by characterized using various techniques. The catalytic performance of the zeolites for the aromatization of 1-hexene was investigated. The results indicate that isomorphous substitution promotes the incorporation of Ga heteroatoms into the framework along with the formation of extra-framework GaO;species（[GaO;]a） that have stronger interactions with the negative potential of the framework. In addition, based on the Py-IR results and catalytic performance, the [GaO;]aspecies with stronger Lewis acid sites produced a better synergism with moderate Br?nsted acid sites and thus improved the selectivity to aromatic compounds. However, the impregnation results in the formation of Ga;O;phase and small amounts of GaO;species that are mainly located on the external surface（[GaO;];）, which contribute to weaker Lewis acid sites due to weaker interactions with the zeolite framework. During 1-hexene aromatization, the nanosized Ga isomorphously substituted ZSM-5 zeolite samples（Gax-NZ5） exhibited better catalytic performance compared to the impregnated samples, and the highest aromatic yield（i.e.,65.4 wt%） was achieved over the Ga4.2-NZ5 sample, which contained with the highest Ga content.
文摘In order to improve the accuracy and integrality of mining data records from the web, the concepts of isomorphic page and directory page and three algorithms are proposed. An isomorphic web page is a set of web pages that have uniform structure, only differing in main information. A web page which contains many links that link to isomorphic web pages is called a directory page. Algorithm 1 can find directory web pages in a web using adjacent links similar analysis method. It first sorts the link, and then counts the links in each directory. If the count is greater than a given valve then finds the similar sub-page links in the directory and gives the results. A function for an isomorphic web page judgment is also proposed. Algorithm 2 can mine data records from an isomorphic page using a noise information filter. It is based on the fact that the noise information is the same in two isomorphic pages, only the main information is different. Algorithm 3 can mine data records from an entire website using the technology of spider. The experiment shows that the proposed algorithms can mine data records more intactly than the existing algorithms. Mining data records from isomorphic pages is an efficient method.
基金The Natural Science Foundation of Jiangsu Province(No.BK2012736)the Natural Science Foundation of Chuzhou University(No.2010kj006Z)
文摘The linear operations of the equivalent classes of crossed modules of Lie color algebras are studied. The set of the equivalent classes of crossed modules is proved to be a vector space, which is isomorphic with the homogeneous components of degree zero of the third cohomology group of Lie color algebras. As an application of this theory, the crossed modules of Witt type Lie color algebras is described, and the result is proved that there is only one equivalent class of the crossed modules of Witt type Lie color algebras when the abelian group Г is equal to Г＋. Finally, for a Witt type Lie color algebra, the classification of its crossed modules is obtained by the isomorphism between the third cohomology group and the crossed modules.
文摘In this paper, the character matrix x n is studied, fast construction method of matrix X 2m is provided. And it is proved that the lower bound estimate of the number of an Latin squares matrix D[X m] is2m(2m)!+∑mi=2[(2m)!] 2∏ij=1K j!∏rj=1b j!.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB911100)of the Ministry of Science and Technology of China
文摘To achieve de novo protein structure determination of challenging cases, multi-wavelength anomalous diffraction(MAD) and multiple isomorphous replacement(MIR) phasing can be powerful tools to obtain low-resolution initial phases from heavy-atom derivative datasets, then phase extension is needed against high-resolution data to obtain accurate structures.In this context, we propose a direct-methods procedure here that could improve the initial low-resolution MAD/MIR phase quality.And accordingly, an automated process for extending initial phases to high resolution is also described.These two procedures are both implanted in the newly released IPCAS pipeline.Three cases are used to perform the test, including one set of 4.17 ? MAD data from a membrane protein and two sets of MAD/MIR data with derivatives truncated down to 6.80 ? and 6.90 ?, respectively.All the results have shown that the initial phases generated from the direct-methods procedure are better than that from the conventional MAD/MIR methods.The automated phase extensions for the latter two cases starting from 6.80 ? to 3.00 ? and 6.90 ? to 2.80 ? are proved to be successful, leading to complete models.This may provide convenient and reliable tools for phase improvement and phase extension in difficult low-resolution tasks.
基金supported by the National Natural Science Foundation of China (20733003,20871114 and 20801055)the Science Foundation of CAS (KJCX2-YW-M05 and KJCX2-YW-H20)of Fujian Province (2009HZ0006-1,2006L2005)
文摘Solvothermal reaction of lanthanide（Ⅲ） salts with fluorescein （2-（6-hydroxy3-oxo-3H-xanthen-9-yl）benzoic acid） led to a series of new coordination polymers {[Ln（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·DMF} n （Ln=Er,Eu,Gd,Tb,Tm,Yb）.The PXRD patterns of the complexes indicate they are isomorphous.The structure of complex {[Er（C 20 H 11 O 5）（C 20 H 10 O 5）（H 2 O）]·DMF} n has been determined by single-crystal X-ray diffraction,revealing a 2D framework in which DMF molecules were filled between the layers.The crystal structure belongs to the triclinic system,space group P1,with a=12.107（4）,b=12.232（4）,c=13.273（4）,α=68.005（7）,β=88.024（11）,γ=77.451（8）°,V=1776.7（9） 3,Z=2,D c=1.720 g/cm 3,μ=2.434 mm-1,F（000）=918,R int=0.0584,T=293（2） K,the final R=0.0621 and wR=0.1501.
基金This work is partially supported by D.G.E.S. PB 96-1338-CO2-01 and the Junta de Andalucla.
文摘A sufficient condition is given to assert that a continuous mapping between Rm and Rn has a zero. The constructive proof of the result is based upon continuation methods and supplies the existence of a path leading to the zero point.
