A novel β-cyclodextrin(β-CD)derivative bearing diethanolamine moiety was synthesized by a convenient method with 63% yield,and the new host compound was characterized by (13)~C-NMR,FT-IR spectra etc,
Two coordination polymers with 1,4-benzenedicarboxylic acid（H2BDC） ligand, namely, [Tb3（BDC）（4.5）（H2O）（DMF）2]n （1） and [Tb2（BDC）3（H2O）2（DMF）2]n（2）, have been synthesized and characterized. Both com...Two coordination polymers with 1,4-benzenedicarboxylic acid（H2BDC） ligand, namely, [Tb3（BDC）（4.5）（H2O）（DMF）2]n （1） and [Tb2（BDC）3（H2O）2（DMF）2]n（2）, have been synthesized and characterized. Both compounds crystallize in the triclinic system, space group P1. For compound 1, a = 10.8528（5）, b = 12.2516（5）, c = 16.9031（7） A, α = 104.462（1）, β = 93.659（1）, γ = 101.404（1）°, V = 2118.1（2） A^3, Z = 2, C（42）H（34）N2O（21）Tb3, Mr = 1379.47, Dc = 2.163 g/cm^3, μ = 5.045 mm^-1, F（000） = 1326, the final R = 0.0212 and wR = 0.0570 for 8592 observed reflections with I 〉 2σ（I）. For compound 2, a = 8.547（1）, b = 10.170（1）, c = 11.192（1）A？, α = 65.531（1）, β = 71.886（1）, γ = 78.796（1）°, V = 839.2（2） A^3, Z = 1, C（30）H（30）N2O（16）Tb2, Mr = 992.40, Dc = 1.964 g/cm^3, μ = 4.257 mm^-1, F（000） = 482, the final R = 0.0220 and wR = 0.0649 for 3626 observed reflections with I 〉 2σ（I）. The compounds exhibit different structural topologies depending on the nature of templating agents in the reactions though the templating agents are not incorporated in the final solids. Compound 1 exhibits a three-dimensional（3D） framework based on the rod-shaped terbium-carboxylate building blocks constructed from linear trinuclear Tb3 units. Compound 2 has a 3D framework containing two interpenetrating pcu topological networks based on the 6-connected dinuclear Tb2 secondary building units. Photoluminescence studies show both compounds exhibit typical Tb（Ⅲ） luminescence emissions. An efficient ligand-to-Tb（Ⅲ） energy transfer is observed in the emission spectra for both compounds.展开更多
The structural properties, heats of formation, elastic properties, and electronic structures of four compositions of binary A1-Li intermetallics, A13Li, A1Li, A12Li3, and A14Li9, are ana- lyzed in detail by using dens...The structural properties, heats of formation, elastic properties, and electronic structures of four compositions of binary A1-Li intermetallics, A13Li, A1Li, A12Li3, and A14Li9, are ana- lyzed in detail by using density functional theory. The calculated formation heats indicate a strong chemical interaction between A1 and Li for all the A1-Li intermetallics. In partic- ular, in the Li-rich A1-Li compounds, the thermodynamic stability of intermetallics linearly decreases with increasing concentration of.Li. According to the computational single crystal elastic constants, all the four A1-Li intermetallic compounds considered here are mechani- cally stable. The polycrystalline elastic modulus and Poisson＇s ratio have been deduced by using Voigt, Reuss, and Hill approximations, and the calculated ratios of bulk modulus to shear modulus indicate that the four compositions of binary A1-Li intermetallics are brittle materials. With the increase of Li concentration, the bulk modulus of A1-Li intermetallics decreases in a linear manner.展开更多
Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when...Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic （IEM） transition above Tc becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg·K as the field changes from 0 to 5T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.展开更多
Magnetic properties and structures in La1-zPrz(Fe0.895–xCoxSi0.105)13 (x=0.07, 0.08; z=0, 0.2, 0.4) compounds were investigated. When Pr and Co substituted for La and Fe, the Curie temperature of the compounds was ad...Magnetic properties and structures in La1-zPrz(Fe0.895–xCoxSi0.105)13 (x=0.07, 0.08; z=0, 0.2, 0.4) compounds were investigated. When Pr and Co substituted for La and Fe, the Curie temperature of the compounds was adjusted to around room temperature. The magnetic phase transition was driven from first-order to second-order due to Co substitution. As a second-order phase transition material, the MCE of La0.6Pr0.4(Fe0.825Co0.07Si0.105)13, whose relative cooling power was 175 J/kg under a field change of 2 T, ...展开更多
Over-expression of glutathione S-transferase(GST)can promote Cisplatin resistance in hepatocellular carcinoma(HCC)treatment.Hence,inhibiting GST is an attractive strategy to improve Cisplatin sensitivity in HCC therap...Over-expression of glutathione S-transferase(GST)can promote Cisplatin resistance in hepatocellular carcinoma(HCC)treatment.Hence,inhibiting GST is an attractive strategy to improve Cisplatin sensitivity in HCC therapy.Although several synthesized GST inhibitors have been developed,the side effects and narrow spectrum for anticancer seriously limit their clinical application.Considering the abundance of natural compounds with anticancer activity,this study developed a rapid fluorescence technique to screen“green”natural GST inhibitors with high specificity.The fluorescence assay demonstrated that schisanlactone B(hereafter abbreviated as C1)isolated from Xue tong significantly down-regulated GST levels in Cisplatin-resistant HCC cells in vitro and in vivo.Importantly,C1 can selectively kill HCC cells from normal liver cells,effectively improving the therapeutic effect of Cisplatin on HCC mice by downregulating GST expression.Considering the high GST levels in HCC patients,this compound demonstrated the high potential for sensitizing HCC therapy in clinical practice by down-regulating GST levels.展开更多
The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orth...The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orthorhombic structure with space group of Cmcm and Z = 4. There are four kinds of nonequivalent 4c crystal positions in EuTrGaa-r unit cell, which are occupied by 4Eu, 4GaⅠ, 4（GaⅡ, T） and 4GaⅢ, respectively. EuTrGa3-r ex- hibits the complex magnetic states in low-temperature regime, with the three-, two- and one-antiferromagnetic transitions occurring for T=Ir, T=Rh and T=Pd, respectively. It might be due to the Kondo effect： a localized antiferromagnetic interaction of the isolated impurity spins with the surrounding conduction electrons at low-temperature regime.展开更多
The hydrogen absorption of the LaFe（10.9）-Co（0.8）Si（1.3） compound under constant 1.01 × 10-5 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie tempe...The hydrogen absorption of the LaFe（10.9）-Co（0.8）Si（1.3） compound under constant 1.01 × 10-5 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie temperature, phase transition and magnetic property were investigated by X-ray diffraction（XRD）, differential scanning calorimeter（DSC） and superconducting quantum interference device,respectively. The hydrides of LaFe（10.9）Co（0.8）Si（1.3） crystallize into NaZn（13）-type structural phase after hydrogen absorption at temperature from 548 to 623 K. Lower hydrogen absorption temperature is of no advantage for pure 1：13 phase formation in a flow H2 atmosphere. The Curie temperature（TC） of LaFe（10.9）Co（0.8）Si（1.3） compound increases by70 K or more after hydrogen absorption. For LaFe（10.9）-Co（0.8）Si（1.3）H（1.8） compound, the maximum magnetic entropy change and the relative cooling power under a magnetic field change of 0-2 T are 6.1 J·kg^-1·K^-1 and 170 J·kg^-1,respectively. Large refrigerant capacity, low hysteresis loss and wide temperature span of magnetic entropy change peak make it a competitive practical candidate for magnetic refrigerant.展开更多
Here we report the fabrication and superconductivity of the iron-based arsenic oxide SmO1-xFxFeAs compound. X-ray diffraction （XRD） results prove that the lattice parameters a and c decrease systematically with incr...Here we report the fabrication and superconductivity of the iron-based arsenic oxide SmO1-xFxFeAs compound. X-ray diffraction （XRD） results prove that the lattice parameters a and c decrease systematically with increasing x in between 0〈x≤0.35, but when x〉0.35 the a and c increase with the decrease of x in the SmO1-xFxFeAs. The critical temperature （To） increases with increasing x in between 0.15≤x≤0.3, while x〉0.3 the Tc decreases with the increase ofx. It is found that at x=0.3 SmO0.7F0.3FeAs has the highest onset resistivity transition temperature of 55.5 K. The critical current density （Jc） value at 10 K for the obtained SmO0.TF0.3FeAs is 1.3×10^5 A/cm^2 （0 T）. Meanwhile one can estimates Hc2（0） from the slope of the Hc2（T） curve at T=-Tc （Hc2 is the upper critical field）, and for the 90% normal-state resistivity （Pn） criterion （Tc=55 K）, Hc2（0） is determined to be -253 T.展开更多
The first synthesis and structural characterization by X-ray crystallography of racemic 2,2＇-dihydroxy-[1,1＇]binaphthalenyl-3,3＇-bis-hydroxamic acids were reported.The com-pound（C28H30N4O8,Mr = 550.56） crystalliz...The first synthesis and structural characterization by X-ray crystallography of racemic 2,2＇-dihydroxy-[1,1＇]binaphthalenyl-3,3＇-bis-hydroxamic acids were reported.The com-pound（C28H30N4O8,Mr = 550.56） crystallizes in orthorhombic system,Fdd2 space group with a = 13.055（3）,b = 34.871（7）,c = 12.570（3） ,V = 5722（2） 3,Z = 8,Dc = 1.278 g/cm3,λ = 0.71073 ,μ（MoKα） = 0.095 mm-1,F（000） = 2320,S = 1.021,R = 0.0349 and wR = 0.0802 for 1757 observed reflections with I 〉 2σ（I）.The N-H and O atom are involved in two-dimensional intermolecular hydrogen bond nets,which further stabilize the structure.展开更多
The possible geometries of Fe(HCN)n (n = 1~6) compounds were studied by using + DFT/UB3LYP/6-31G(2df) method. The structure and ground state ...The possible geometries of Fe(HCN)n (n = 1~6) compounds were studied by using + DFT/UB3LYP/6-31G(2df) method. The structure and ground state of each fragmental ion are C∞v (4Σ+ or Σ ), D∞h (4Σg ), D3 (4A1 ), C2 or Td or C3v (4A1), and D3 (4A1 ) or C4 ( A1 ) sequentially 6 + + ′ ′ ′ 2 ′ h v h v with n = 1～5. For the compound Fe(HCN)6 , the possible geometry was not obtained. The + sequential incremental interaction energy (–?(?E)), dissociation energy (?D0), enthalpy (–?(?H)) and Gibbs free energy (–?(?G)), and frequencies for HCN-Fe(HCN)n + -1 were also calculated, and the results are all in good agreement with the experiments. The bond length of Fe–N is lengthened with the increase of cluster size, and the strength of Fe+–N coordination bond varies nonmon- tonically as increasing the number of ligands. The Fe+–N bond of Fe(HCN)2 is the strongest in all + compounds.展开更多
The electrical conductivity and Hall effect for T1GaSeS crystals have been investigated over a wide temperature range. The crystals we used are grown by a modified Bridgman technique and possess p-type conductivity. T...The electrical conductivity and Hall effect for T1GaSeS crystals have been investigated over a wide temperature range. The crystals we used are grown by a modified Bridgman technique and possess p-type conductivity. The energy gap has been found to be 1.63 eV, whereas the ionization energy is 0.25 eV. The variations of the Hall mobility as well as the carrier concentration with temperature have been investigated. The scattering mechanisms of the carder are checked over the whole investigated temperature range. Furthermore, the diffusion coefficient, relaxation time, and diffusion length of holes are estimated.展开更多
The stability of the coordination compounds of the first transition series metal ions(Mn(Ⅱ),Co(Ⅱ),Ni(Ⅱ),Cu(Ⅱ)and Zn(Ⅱ))with 2-mercaptopyridine-1- oxide is reported.A coordination compound CoL_2 is synthesized and...The stability of the coordination compounds of the first transition series metal ions(Mn(Ⅱ),Co(Ⅱ),Ni(Ⅱ),Cu(Ⅱ)and Zn(Ⅱ))with 2-mercaptopyridine-1- oxide is reported.A coordination compound CoL_2 is synthesized and characterized for the first time.展开更多
Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all ...Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm content.Magnetic measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.展开更多
Mono-substituted heterocyclic ketene aminals are formed by the reaction of 1-methyl-2-methylthio-imidazoline with active methylene compounds containinq an acetyl or benzoyl group by the elimination of both a methylthi...Mono-substituted heterocyclic ketene aminals are formed by the reaction of 1-methyl-2-methylthio-imidazoline with active methylene compounds containinq an acetyl or benzoyl group by the elimination of both a methylthio and an acyl group.This is resulted by the secondary reactio of the produced methanethiol to attack the more active carbonyl group.展开更多
The phases and magnetocaloric effect in the alloys (Gd1-xErx)5Si1.8Ge2.2 with x=0, 0.1, 0.2 and 0.3 were investigated by X-ray diffraction analysis and magnetization measurement. The samples were single phase with the...The phases and magnetocaloric effect in the alloys (Gd1-xErx)5Si1.8Ge2.2 with x=0, 0.1, 0.2 and 0.3 were investigated by X-ray diffraction analysis and magnetization measurement. The samples were single phase with the monoclinic Gd5Si2Ge2-type structure. With the increase of Er content, the Curie temperature (Tc) decreased obviously from 253 K of the alloy with x=0 to 114 K with x=0.3. The maximum magnetic entropy changed in the samples of (Gd1-xErx)5Si1.8Ge2.2 with x=0.0, 0.1, 0.2 and 0.3 were 6.88, 8.32, 9.59 and 10.24 J·kg-1·K-1 respectively in the applied field change of 0～2.0 T.展开更多
In this work, while applying a new and novel (G'/G)-expansion version technique, we identify four families of the traveling wave solutions to the (1 + 1)-dimensional compound KdVB equation. The exact solutions are...In this work, while applying a new and novel (G'/G)-expansion version technique, we identify four families of the traveling wave solutions to the (1 + 1)-dimensional compound KdVB equation. The exact solutions are derived, in terms of hyperbolic, trigonometric and rational functions, involving various parameters. When the parameters are tuned to special values, both solitary, and periodic wave models are distinguished. State of the art symbolic algebra graphical representations and dynamical interpretations of the obtained solutions physics are provided and discussed. This in turn ends up revealing salient solutions features and demonstrating the used method efficiency.展开更多
文摘A novel β-cyclodextrin(β-CD)derivative bearing diethanolamine moiety was synthesized by a convenient method with 63% yield,and the new host compound was characterized by (13)~C-NMR,FT-IR spectra etc,
基金Supported by the NNSFC(21361011)the Provincial Natural Science Foundation of Jiangxi(20151BAB203002)+1 种基金the Project of Education Department of Jiangxi Province(GJJ14235)the Open Project Program of Key Laboratory of Functional Small Organic Molecule,Ministry of Education,Jiangxi Normal University(KLFS-KF-201412)
文摘Two coordination polymers with 1,4-benzenedicarboxylic acid（H2BDC） ligand, namely, [Tb3（BDC）（4.5）（H2O）（DMF）2]n （1） and [Tb2（BDC）3（H2O）2（DMF）2]n（2）, have been synthesized and characterized. Both compounds crystallize in the triclinic system, space group P1. For compound 1, a = 10.8528（5）, b = 12.2516（5）, c = 16.9031（7） A, α = 104.462（1）, β = 93.659（1）, γ = 101.404（1）°, V = 2118.1（2） A^3, Z = 2, C（42）H（34）N2O（21）Tb3, Mr = 1379.47, Dc = 2.163 g/cm^3, μ = 5.045 mm^-1, F（000） = 1326, the final R = 0.0212 and wR = 0.0570 for 8592 observed reflections with I 〉 2σ（I）. For compound 2, a = 8.547（1）, b = 10.170（1）, c = 11.192（1）A？, α = 65.531（1）, β = 71.886（1）, γ = 78.796（1）°, V = 839.2（2） A^3, Z = 1, C（30）H（30）N2O（16）Tb2, Mr = 992.40, Dc = 1.964 g/cm^3, μ = 4.257 mm^-1, F（000） = 482, the final R = 0.0220 and wR = 0.0649 for 3626 observed reflections with I 〉 2σ（I）. The compounds exhibit different structural topologies depending on the nature of templating agents in the reactions though the templating agents are not incorporated in the final solids. Compound 1 exhibits a three-dimensional（3D） framework based on the rod-shaped terbium-carboxylate building blocks constructed from linear trinuclear Tb3 units. Compound 2 has a 3D framework containing two interpenetrating pcu topological networks based on the 6-connected dinuclear Tb2 secondary building units. Photoluminescence studies show both compounds exhibit typical Tb（Ⅲ） luminescence emissions. An efficient ligand-to-Tb（Ⅲ） energy transfer is observed in the emission spectra for both compounds.
文摘The structural properties, heats of formation, elastic properties, and electronic structures of four compositions of binary A1-Li intermetallics, A13Li, A1Li, A12Li3, and A14Li9, are ana- lyzed in detail by using density functional theory. The calculated formation heats indicate a strong chemical interaction between A1 and Li for all the A1-Li intermetallics. In partic- ular, in the Li-rich A1-Li compounds, the thermodynamic stability of intermetallics linearly decreases with increasing concentration of.Li. According to the computational single crystal elastic constants, all the four A1-Li intermetallic compounds considered here are mechani- cally stable. The polycrystalline elastic modulus and Poisson＇s ratio have been deduced by using Voigt, Reuss, and Hill approximations, and the calculated ratios of bulk modulus to shear modulus indicate that the four compositions of binary A1-Li intermetallics are brittle materials. With the increase of Li concentration, the bulk modulus of A1-Li intermetallics decreases in a linear manner.
基金Project supported by the National Natural Science Foundation of China （Grant No 50571112）, the National Basic Reseaxch Program of China （Grant No 2006CB601101） and the Program of Chinese Academy of Sciences （Grant No KJCX2-YW-W02）.
文摘Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic （IEM） transition above Tc becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg·K as the field changes from 0 to 5T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.
基金Project supported by the National Basic Research Program of China (2006CB601101)the National High Technology Research and Development Program of China (2007AA03Z440)the National Natural Science Foundation of China (50731007)
文摘Magnetic properties and structures in La1-zPrz(Fe0.895–xCoxSi0.105)13 (x=0.07, 0.08; z=0, 0.2, 0.4) compounds were investigated. When Pr and Co substituted for La and Fe, the Curie temperature of the compounds was adjusted to around room temperature. The magnetic phase transition was driven from first-order to second-order due to Co substitution. As a second-order phase transition material, the MCE of La0.6Pr0.4(Fe0.825Co0.07Si0.105)13, whose relative cooling power was 175 J/kg under a field change of 2 T, ...
基金supported by the National Natural Science Foundation of China(Grant Nos.:82003931,82204766 and 81374062)the Outstanding Youth Foundation of Hunan Provincial Education Department of China(Grant No.:20B445)+3 种基金the Hunan Youth Science and Technology Innovation Talents Project,China(Grant No.:2021RC3100)the Chinese Postdoctoral Science foundation(Grant No.:2021M690974)Changjiang Scholars Program in Ministry Education,People's Republic of China(Program No.:T2019133)the Scientific Research Project of Hunan Provincial Education Department(Project No.:21B0394).
文摘Over-expression of glutathione S-transferase(GST)can promote Cisplatin resistance in hepatocellular carcinoma(HCC)treatment.Hence,inhibiting GST is an attractive strategy to improve Cisplatin sensitivity in HCC therapy.Although several synthesized GST inhibitors have been developed,the side effects and narrow spectrum for anticancer seriously limit their clinical application.Considering the abundance of natural compounds with anticancer activity,this study developed a rapid fluorescence technique to screen“green”natural GST inhibitors with high specificity.The fluorescence assay demonstrated that schisanlactone B(hereafter abbreviated as C1)isolated from Xue tong significantly down-regulated GST levels in Cisplatin-resistant HCC cells in vitro and in vivo.Importantly,C1 can selectively kill HCC cells from normal liver cells,effectively improving the therapeutic effect of Cisplatin on HCC mice by downregulating GST expression.Considering the high GST levels in HCC patients,this compound demonstrated the high potential for sensitizing HCC therapy in clinical practice by down-regulating GST levels.
基金Supported by the National Natural Science Foundation of China under Grant No 11274110
文摘The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orthorhombic structure with space group of Cmcm and Z = 4. There are four kinds of nonequivalent 4c crystal positions in EuTrGaa-r unit cell, which are occupied by 4Eu, 4GaⅠ, 4（GaⅡ, T） and 4GaⅢ, respectively. EuTrGa3-r ex- hibits the complex magnetic states in low-temperature regime, with the three-, two- and one-antiferromagnetic transitions occurring for T=Ir, T=Rh and T=Pd, respectively. It might be due to the Kondo effect： a localized antiferromagnetic interaction of the isolated impurity spins with the surrounding conduction electrons at low-temperature regime.
基金financially supported by the Tianjin Research Program of Application Foundation and Advanced Technology (No.14JCQNJC04000)the National Key Research and Development Program of China (No.2017YFB0702700)the Hebei Provincial Education Department Project (No.ZD2017066)
文摘The hydrogen absorption of the LaFe（10.9）-Co（0.8）Si（1.3） compound under constant 1.01 × 10-5 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie temperature, phase transition and magnetic property were investigated by X-ray diffraction（XRD）, differential scanning calorimeter（DSC） and superconducting quantum interference device,respectively. The hydrides of LaFe（10.9）Co（0.8）Si（1.3） crystallize into NaZn（13）-type structural phase after hydrogen absorption at temperature from 548 to 623 K. Lower hydrogen absorption temperature is of no advantage for pure 1：13 phase formation in a flow H2 atmosphere. The Curie temperature（TC） of LaFe（10.9）Co（0.8）Si（1.3） compound increases by70 K or more after hydrogen absorption. For LaFe（10.9）-Co（0.8）Si（1.3）H（1.8） compound, the maximum magnetic entropy change and the relative cooling power under a magnetic field change of 0-2 T are 6.1 J·kg^-1·K^-1 and 170 J·kg^-1,respectively. Large refrigerant capacity, low hysteresis loss and wide temperature span of magnetic entropy change peak make it a competitive practical candidate for magnetic refrigerant.
基金supported by the National Basic Research Program of China (No. 2006CB601005)the National High Technology Research and Development Program of China (No. 2009AA032401)+1 种基金the National Natural Science Foundation of China (Nos. 50771003 and 50802004)Beijing Municipal Natural Science Foundation (No.2092006)
文摘Here we report the fabrication and superconductivity of the iron-based arsenic oxide SmO1-xFxFeAs compound. X-ray diffraction （XRD） results prove that the lattice parameters a and c decrease systematically with increasing x in between 0〈x≤0.35, but when x〉0.35 the a and c increase with the decrease of x in the SmO1-xFxFeAs. The critical temperature （To） increases with increasing x in between 0.15≤x≤0.3, while x〉0.3 the Tc decreases with the increase ofx. It is found that at x=0.3 SmO0.7F0.3FeAs has the highest onset resistivity transition temperature of 55.5 K. The critical current density （Jc） value at 10 K for the obtained SmO0.TF0.3FeAs is 1.3×10^5 A/cm^2 （0 T）. Meanwhile one can estimates Hc2（0） from the slope of the Hc2（T） curve at T=-Tc （Hc2 is the upper critical field）, and for the 90% normal-state resistivity （Pn） criterion （Tc=55 K）, Hc2（0） is determined to be -253 T.
基金Supported by the National Natural Science Foundation of China (No. 20971029)Natural Science Foundation of Guangxi Province (No. 2010GXNSFD013018 and 2010GXNSFF013001)
文摘The first synthesis and structural characterization by X-ray crystallography of racemic 2,2＇-dihydroxy-[1,1＇]binaphthalenyl-3,3＇-bis-hydroxamic acids were reported.The com-pound（C28H30N4O8,Mr = 550.56） crystallizes in orthorhombic system,Fdd2 space group with a = 13.055（3）,b = 34.871（7）,c = 12.570（3） ,V = 5722（2） 3,Z = 8,Dc = 1.278 g/cm3,λ = 0.71073 ,μ（MoKα） = 0.095 mm-1,F（000） = 2320,S = 1.021,R = 0.0349 and wR = 0.0802 for 1757 observed reflections with I 〉 2σ（I）.The N-H and O atom are involved in two-dimensional intermolecular hydrogen bond nets,which further stabilize the structure.
基金This research was supported by the National Natural Science Foundation of China (20273013 20303002)+1 种基金 the Key Foundation of Fujian Province (K02012) the Foundation of State Key Laboratory of Structural Chemistry (020051) and of Fuzhou University
文摘The possible geometries of Fe(HCN)n (n = 1~6) compounds were studied by using + DFT/UB3LYP/6-31G(2df) method. The structure and ground state of each fragmental ion are C∞v (4Σ+ or Σ ), D∞h (4Σg ), D3 (4A1 ), C2 or Td or C3v (4A1), and D3 (4A1 ) or C4 ( A1 ) sequentially 6 + + ′ ′ ′ 2 ′ h v h v with n = 1～5. For the compound Fe(HCN)6 , the possible geometry was not obtained. The + sequential incremental interaction energy (–?(?E)), dissociation energy (?D0), enthalpy (–?(?H)) and Gibbs free energy (–?(?G)), and frequencies for HCN-Fe(HCN)n + -1 were also calculated, and the results are all in good agreement with the experiments. The bond length of Fe–N is lengthened with the increase of cluster size, and the strength of Fe+–N coordination bond varies nonmon- tonically as increasing the number of ligands. The Fe+–N bond of Fe(HCN)2 is the strongest in all + compounds.
文摘The electrical conductivity and Hall effect for T1GaSeS crystals have been investigated over a wide temperature range. The crystals we used are grown by a modified Bridgman technique and possess p-type conductivity. The energy gap has been found to be 1.63 eV, whereas the ionization energy is 0.25 eV. The variations of the Hall mobility as well as the carrier concentration with temperature have been investigated. The scattering mechanisms of the carder are checked over the whole investigated temperature range. Furthermore, the diffusion coefficient, relaxation time, and diffusion length of holes are estimated.
文摘The stability of the coordination compounds of the first transition series metal ions(Mn(Ⅱ),Co(Ⅱ),Ni(Ⅱ),Cu(Ⅱ)and Zn(Ⅱ))with 2-mercaptopyridine-1- oxide is reported.A coordination compound CoL_2 is synthesized and characterized for the first time.
基金financially supported by the State Key Development Program of Basic Research of China (No. 2010CB934600)State Key Laboratory of Advanced Metals and Materials (No. 2011-ZD02)the Project of Construction of Innovative Teams and Teacher Career Development for Universities and Colleges under Beijing Municipality (No. 009000543113507)
文摘Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm content.Magnetic measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.
文摘Mono-substituted heterocyclic ketene aminals are formed by the reaction of 1-methyl-2-methylthio-imidazoline with active methylene compounds containinq an acetyl or benzoyl group by the elimination of both a methylthio and an acyl group.This is resulted by the secondary reactio of the produced methanethiol to attack the more active carbonyl group.
基金Project supported by the Natural Science Foundation of Guangxi ,China (0249012)
文摘The phases and magnetocaloric effect in the alloys (Gd1-xErx)5Si1.8Ge2.2 with x=0, 0.1, 0.2 and 0.3 were investigated by X-ray diffraction analysis and magnetization measurement. The samples were single phase with the monoclinic Gd5Si2Ge2-type structure. With the increase of Er content, the Curie temperature (Tc) decreased obviously from 253 K of the alloy with x=0 to 114 K with x=0.3. The maximum magnetic entropy changed in the samples of (Gd1-xErx)5Si1.8Ge2.2 with x=0.0, 0.1, 0.2 and 0.3 were 6.88, 8.32, 9.59 and 10.24 J·kg-1·K-1 respectively in the applied field change of 0～2.0 T.
文摘In this work, while applying a new and novel (G'/G)-expansion version technique, we identify four families of the traveling wave solutions to the (1 + 1)-dimensional compound KdVB equation. The exact solutions are derived, in terms of hyperbolic, trigonometric and rational functions, involving various parameters. When the parameters are tuned to special values, both solitary, and periodic wave models are distinguished. State of the art symbolic algebra graphical representations and dynamical interpretations of the obtained solutions physics are provided and discussed. This in turn ends up revealing salient solutions features and demonstrating the used method efficiency.
