The single crystal of two-electron heteropoly blue with Si as the heteroatom and α-Keggin structure K_2H_4SiMo(Ⅴ)_2Mo(Ⅵ)_(10)O_(40)·12H_2O was obtained by electrolytic reduction. It crystallizes in a triclinic...The single crystal of two-electron heteropoly blue with Si as the heteroatom and α-Keggin structure K_2H_4SiMo(Ⅴ)_2Mo(Ⅵ)_(10)O_(40)·12H_2O was obtained by electrolytic reduction. It crystallizes in a triclinic system with space group P , Mr=2117.73, a= 13.702(4), b=14.107(3), c=14.184(2) ; α=119.27(1), β=93.14(2), ;γ=110. 3(2)°, V=2154.29~3, Z=2, F(000)=1999, μ=36.39cm^(-1), Dc=3.26 g/cm^3. Final R factor is 0.0515. Mo(Ⅴ) is situated in two different edge-shared Mo_3O_(13) groups. The heteropoly blue was characterized by IR, UV, polarography, X-ray photoelectron spectra and ESR. All the results show that the structure of the heteropoly anion with Keggin structure remains unchanged basically in the process of reduction.展开更多
Some K_2NiF_4-type oxides(A_2BO_4) exhibited good catalytic activity for oxidative coupling of methane to form ethane and ethylene. The C_2 selectivity was well correlated with A-site ion when B-site was Ti^(4+) ion.
The title compound 1β-hydroxydigitoxigenin（1） was isolated from the ethanol extract of the roots of Streptocaulon juventas. The crystal structure of 1, C23H34O5·H2O, was determined by Synchrotron X-ray diffrac...The title compound 1β-hydroxydigitoxigenin（1） was isolated from the ethanol extract of the roots of Streptocaulon juventas. The crystal structure of 1, C23H34O5·H2O, was determined by Synchrotron X-ray diffraction analysis due to small crystal size（0.14 mm × 0.04 mm × 0.01 mm）. The crystal belongs to monoclinic, space group P21, with a = 7.6624（15）, b= 13.460（3）, c = 10.370（2） A, b = 92.40（3）°, V = 1068.6（4）A^3, Z = 2, Mr = 406.50, Dx = 1.263 g/cm^3, λ（synchrotron） = 1.2399 A, μ（synchrotron 1.23990） = 0.333 cm^-1, F（000） = 550, S = 1.059, R = 0.0625 and wR = 0.1687 for 4247 unique reflections, of which 3687 were observed（I 〉 2σ（I））. The asymmetric unit contains one independent molecule of 1 and one water molecule which are connected through hydrogen bonds. The conformation of 1 in crystalline state is in good agreement with the solution structure in methanol as indicated by ^1H-NMR analysis. The absolute configuration of 1 could be assigned by referring to the known configuration of the lactone ring at C（17b）. In the solid state, intermolecular hydrogen bonds involving carbonyl group in the lactone moiety and the hydroxyl groups in the steroid moiety ester linked adjacent molecules into a three-dimensional network. Compound 1 showed significant inhibition on Na^＋/K^＋-ATPase with an IC50 of 2.46 mM, which is stronger thiocarbonylbufalin but weaker than a close analog digitoxigenin, suggesting that a lactone ring is important and the substitution of a hydroxyl group at C（1） is not favored for the inhibition of Na^＋/K^＋-ATPase.展开更多
For the first time, DySrA104 of K2NiF4-type structure was synthesized. The parameters of DySrA104 ele- mentary unit cell are determined as follows： a = 0.368 （4） nm, c = 1.229 （2） nm, V = 0.166 （4） nm3. The res...For the first time, DySrA104 of K2NiF4-type structure was synthesized. The parameters of DySrA104 ele- mentary unit cell are determined as follows： a = 0.368 （4） nm, c = 1.229 （2） nm, V = 0.166 （4） nm3. The research of the complex aluminates ZnSrA104 （Ln = Nd, Gd, Dy） solid-state process demonstrated the change of the formation mecha- nism among LnSrA104 （Ln = Nd, Gd, Dy） series from DySrA104 oxide. The performed analysis provided a possibility to realize why chemists couldn＇t get DySrA104 for a long period of time.展开更多
K_6CrNb_(15)O_(42)crystallizes in the hexagonal system with a=9.126(3)A,c=12.068(3)A,V= 870.4(5)A^3,and space group P6_2/mcm,Z=1.The structure was solved using direct method and Fourier Techniques.Of the 829 unique re...K_6CrNb_(15)O_(42)crystallizes in the hexagonal system with a=9.126(3)A,c=12.068(3)A,V= 870.4(5)A^3,and space group P6_2/mcm,Z=1.The structure was solved using direct method and Fourier Techniques.Of the 829 unique reflections measured by counter techniques,448 with I≥3σ(I) were used in the least-squares refinement of the model to R=0.034(R_w=0.044).The structure of KoCrNb_(15)O_(42)may be described as consisting of corner-shared and edge-shared octahedra,the ring units composed of six octahedra of Nb(1)are corner-shared one another along the c-axis to form hexagonal column octahedra chains which are connected by K^+ and octahedra of Nb(2).展开更多
This paper studies the properties of Nambu-Poisson geometry from the(n-l,k)-Dirac structure on a smooth manifold M.Firstly,we examine the automorphism group and infinitesimal on higher order Courant algebroid,to prove...This paper studies the properties of Nambu-Poisson geometry from the(n-l,k)-Dirac structure on a smooth manifold M.Firstly,we examine the automorphism group and infinitesimal on higher order Courant algebroid,to prove the integrability of infinitesimal Courant automorphism.Under the transversal smooth morphismΦ:N-→M and anchor mapping of M on(n-1,k)-Dirac structure,it's holds that the pullback(n-1,k)-Dirac structure on M turns out an(n-1,k)-Dirac structure on N.Then,given that the graph of Nambu-Poisson structure takes the form of(n-1,n-2)-Dirac structure,it follows that the single parameter variety of Nambu-Poisson structure is related to one variety closed n-symplectic form under gauge transformation.WhenΦ:N-→M is taken as the immersion mapping of(n-1)-cosymplectic submanifold,the pullback Nambu-Poisson structure on M turns out the Nambu-Poisson structure on N.Finally,we discuss the(n-1,O)-Dirac structure on M can be integrated into a problem of(n-1)-presymplectic groupoid.Under the mapping II:M-→M/H,the corresponding(n-1,O)-Dirac structure is F and E respectively.If E can be integrated into(n-1)-presymplectic groupoid(g,2),then there exists the only,such that the corresponding integral of F is(n-1)-presymplectic groupoid(g,).展开更多
One of the major challenges to develop "intermediate temperature" solid oxide fuel cells is finding a novel cathode material, which can meet the following requirements: (1) high electronic conductivity; (2) ...One of the major challenges to develop "intermediate temperature" solid oxide fuel cells is finding a novel cathode material, which can meet the following requirements: (1) high electronic conductivity; (2) chemical compatibility with the electrolyte; (3) a matched thermal expansion coefficient (TEC); (4) stability in a wide range of oxygen partial pressure; and (5) high catalytic activity for the oxygen reduction reaction (ORR). In this short review, a survey of these requirements for K2NiF4-type material with the formula Ln2MO4, Ln = La, Pr, Nd, Sm; M = Ni, Cu, Fe, Co, Mn, is presented. The composition-dependent TEC, electrical conductivity and oxygen transport property are considered. The Ln2MO4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes. The complete fuel cells integrated with Ln2MO4 materials as cathodes show promising results. Furthermore, these materials are considered as cathodes of protonic ceramic fuel cell (PCFC), and/or anodes of high temperature steam electrolysis (HTSE). First results show excellent performances. The versatility of these Ln2MO4 materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry.展开更多
A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO...A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO2 tolerance,and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied.The results show that higher Ca contents in the material lead to the formation of CaCO3.A constant oxygen permeation flux of about 0.63 mL·min−1·cm−2 at 1173 K through a 0.65 mm thick membrane was measured for(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ,using either helium or pure CO2 as sweep gas.Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration.The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature.In addition,this membrane did not deteriorate in a high-energy CO2 plasma.The present work demonstrates that this(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δmembrane is a promising chemically robust candidate for oxygen separation applications.展开更多
文摘The single crystal of two-electron heteropoly blue with Si as the heteroatom and α-Keggin structure K_2H_4SiMo(Ⅴ)_2Mo(Ⅵ)_(10)O_(40)·12H_2O was obtained by electrolytic reduction. It crystallizes in a triclinic system with space group P , Mr=2117.73, a= 13.702(4), b=14.107(3), c=14.184(2) ; α=119.27(1), β=93.14(2), ;γ=110. 3(2)°, V=2154.29~3, Z=2, F(000)=1999, μ=36.39cm^(-1), Dc=3.26 g/cm^3. Final R factor is 0.0515. Mo(Ⅴ) is situated in two different edge-shared Mo_3O_(13) groups. The heteropoly blue was characterized by IR, UV, polarography, X-ray photoelectron spectra and ESR. All the results show that the structure of the heteropoly anion with Keggin structure remains unchanged basically in the process of reduction.
基金Subject supported by the National Natural Science Foundation of China
文摘Some K_2NiF_4-type oxides(A_2BO_4) exhibited good catalytic activity for oxidative coupling of methane to form ethane and ethylene. The C_2 selectivity was well correlated with A-site ion when B-site was Ti^(4+) ion.
基金supported by the National Natural Science Foundation of China(No.81373956,81274064 and 81573315)the Fundamental Research Funds for the Central Universities(2015ZD010)the Priority Academic Program Development of Jiangsu Higher Education Institutions and Guangzhou Industry-University Collaborative Innovation Major Projects(201508030016)
文摘The title compound 1β-hydroxydigitoxigenin（1） was isolated from the ethanol extract of the roots of Streptocaulon juventas. The crystal structure of 1, C23H34O5·H2O, was determined by Synchrotron X-ray diffraction analysis due to small crystal size（0.14 mm × 0.04 mm × 0.01 mm）. The crystal belongs to monoclinic, space group P21, with a = 7.6624（15）, b= 13.460（3）, c = 10.370（2） A, b = 92.40（3）°, V = 1068.6（4）A^3, Z = 2, Mr = 406.50, Dx = 1.263 g/cm^3, λ（synchrotron） = 1.2399 A, μ（synchrotron 1.23990） = 0.333 cm^-1, F（000） = 550, S = 1.059, R = 0.0625 and wR = 0.1687 for 4247 unique reflections, of which 3687 were observed（I 〉 2σ（I））. The asymmetric unit contains one independent molecule of 1 and one water molecule which are connected through hydrogen bonds. The conformation of 1 in crystalline state is in good agreement with the solution structure in methanol as indicated by ^1H-NMR analysis. The absolute configuration of 1 could be assigned by referring to the known configuration of the lactone ring at C（17b）. In the solid state, intermolecular hydrogen bonds involving carbonyl group in the lactone moiety and the hydroxyl groups in the steroid moiety ester linked adjacent molecules into a three-dimensional network. Compound 1 showed significant inhibition on Na^＋/K^＋-ATPase with an IC50 of 2.46 mM, which is stronger thiocarbonylbufalin but weaker than a close analog digitoxigenin, suggesting that a lactone ring is important and the substitution of a hydroxyl group at C（1） is not favored for the inhibition of Na^＋/K^＋-ATPase.
文摘For the first time, DySrA104 of K2NiF4-type structure was synthesized. The parameters of DySrA104 ele- mentary unit cell are determined as follows： a = 0.368 （4） nm, c = 1.229 （2） nm, V = 0.166 （4） nm3. The research of the complex aluminates ZnSrA104 （Ln = Nd, Gd, Dy） solid-state process demonstrated the change of the formation mecha- nism among LnSrA104 （Ln = Nd, Gd, Dy） series from DySrA104 oxide. The performed analysis provided a possibility to realize why chemists couldn＇t get DySrA104 for a long period of time.
文摘K_6CrNb_(15)O_(42)crystallizes in the hexagonal system with a=9.126(3)A,c=12.068(3)A,V= 870.4(5)A^3,and space group P6_2/mcm,Z=1.The structure was solved using direct method and Fourier Techniques.Of the 829 unique reflections measured by counter techniques,448 with I≥3σ(I) were used in the least-squares refinement of the model to R=0.034(R_w=0.044).The structure of KoCrNb_(15)O_(42)may be described as consisting of corner-shared and edge-shared octahedra,the ring units composed of six octahedra of Nb(1)are corner-shared one another along the c-axis to form hexagonal column octahedra chains which are connected by K^+ and octahedra of Nb(2).
文摘This paper studies the properties of Nambu-Poisson geometry from the(n-l,k)-Dirac structure on a smooth manifold M.Firstly,we examine the automorphism group and infinitesimal on higher order Courant algebroid,to prove the integrability of infinitesimal Courant automorphism.Under the transversal smooth morphismΦ:N-→M and anchor mapping of M on(n-1,k)-Dirac structure,it's holds that the pullback(n-1,k)-Dirac structure on M turns out an(n-1,k)-Dirac structure on N.Then,given that the graph of Nambu-Poisson structure takes the form of(n-1,n-2)-Dirac structure,it follows that the single parameter variety of Nambu-Poisson structure is related to one variety closed n-symplectic form under gauge transformation.WhenΦ:N-→M is taken as the immersion mapping of(n-1)-cosymplectic submanifold,the pullback Nambu-Poisson structure on M turns out the Nambu-Poisson structure on N.Finally,we discuss the(n-1,O)-Dirac structure on M can be integrated into a problem of(n-1)-presymplectic groupoid.Under the mapping II:M-→M/H,the corresponding(n-1,O)-Dirac structure is F and E respectively.If E can be integrated into(n-1)-presymplectic groupoid(g,2),then there exists the only,such that the corresponding integral of F is(n-1)-presymplectic groupoid(g,).
基金supported by the National Natural Science Foundation of China (51072048)Research Project of New Century Excellent Talents in University (NCET-06-0349)Heilongjiang Educational Department (GZ09A204, 1152G027, 11531274 & 11531285)
文摘One of the major challenges to develop "intermediate temperature" solid oxide fuel cells is finding a novel cathode material, which can meet the following requirements: (1) high electronic conductivity; (2) chemical compatibility with the electrolyte; (3) a matched thermal expansion coefficient (TEC); (4) stability in a wide range of oxygen partial pressure; and (5) high catalytic activity for the oxygen reduction reaction (ORR). In this short review, a survey of these requirements for K2NiF4-type material with the formula Ln2MO4, Ln = La, Pr, Nd, Sm; M = Ni, Cu, Fe, Co, Mn, is presented. The composition-dependent TEC, electrical conductivity and oxygen transport property are considered. The Ln2MO4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes. The complete fuel cells integrated with Ln2MO4 materials as cathodes show promising results. Furthermore, these materials are considered as cathodes of protonic ceramic fuel cell (PCFC), and/or anodes of high temperature steam electrolysis (HTSE). First results show excellent performances. The versatility of these Ln2MO4 materials is explained on the basis of structural features and the ability to accommodate oxygen non-stoichiometry.
基金This work is part of the project “Plasma-induced CO2-conversion”(PiCK,project number:03SFK2S3B)and financially supported by the German Federal Ministry of Education and Research in the framework of the“Kopemikus projects for the Energiewende”.The authors are thankfUl to B.Sc.Laura Steinle(University of Stuttgart)for her assistance during the CO stability tests,and Christine Stefani and Prof.Dr.Robert Dinnebier(Max Planck Institute for Solid State Research,Stuttgart)for the in situ PXRD measurements,respectively.G.C.thanks Frank Hack and Dr.Angelika Veziridis for their kind support during experiments and discussions.
文摘A series of novel dense mixed conducting ceramic membranes based on K2NiF4-type(La1-xCax)2(Ni0.75Cu0.25)O4+δwas successfully prepared through a sol-gel route.Their chemical compatibility,oxygen permeability,CO and CO2 tolerance,and long-term CO2 resistance regarding phase composition and crystal structure at different atmospheres were studied.The results show that higher Ca contents in the material lead to the formation of CaCO3.A constant oxygen permeation flux of about 0.63 mL·min−1·cm−2 at 1173 K through a 0.65 mm thick membrane was measured for(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δ,using either helium or pure CO2 as sweep gas.Steady oxygen fluxes with no sign of deterioration of this membrane were observed with increasing CO2 concentration.The membrane showed excellent chemical stability towards CO2 for more than 1360 h and phase stability in presence of CO for 4 h at high temperature.In addition,this membrane did not deteriorate in a high-energy CO2 plasma.The present work demonstrates that this(La0.9Ca0.1)2(Ni0.75Cu0.25)O4+δmembrane is a promising chemically robust candidate for oxygen separation applications.
