It has been an established practice to estimate the Θ-temperature of a polymer solution from thedisappearance of the interchain interactions (A_2 = 0) Recently, in studies of the temperature dependence ofthe chain co...It has been an established practice to estimate the Θ-temperature of a polymer solution from thedisappearance of the interchain interactions (A_2 = 0) Recently, in studies of the temperature dependence ofthe chain conformation in solution, we found that the change of the chain conformation clearly underwentthree different stages which could be viewed as the 'gas'. 'liquid' and 'solid' states in terms of the freedomof the 'blobs' on the chain. The transition temperature between the first and second stages corresponds nicelyto the Θ-temperature determined by the conventional method. It reveals, for the first time, that the Θ-temperature can be deduced from the conformation change of a single polymer chain in solution, which isimportant not only in conception, but also in practice.展开更多
Using the secondary spinel standard, the authors have precisely measured theFe^(3+)/SIGMA Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, andestimated the oxygen fugacities recorded by...Using the secondary spinel standard, the authors have precisely measured theFe^(3+)/SIGMA Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, andestimated the oxygen fugacities recorded by 63 mantle xenoliths through olivine-orthopyroxene-spineloxygen barometry. The results indicate that the oxygen fugacities of the lithospheric mantle ineastern China are higher in the south than in the north. Among them, the oxygen fugacity of theNorth China craton lithospheric mantle is the lowest, similar to that of the oceanic mantle, whilethat of Northeast and South China are the same as that of the global continental mantle. Thevariations of mantle redox state in eastern China are mainly controlled by the C-O-H fluids derivedfrom the asthenospheric mantle. According to the mantle oxidation state, it can be concluded thatthe C-O-H fluids in the lithospheric mantle of eastern China consist mainly of CO_2 and minor H_2O,but CH_4-rich fluids should come from the asthenosphere where the oxidation state is lower.展开更多
The reaction between Laccase and o methoxyphenol have been studied by LKB 2107 batch microcalorimetry system. Thermodynamic parameters Δ rH m , Δ G 0 , Δ G ≠ T ,) and kinetic parameters ( K m,k...The reaction between Laccase and o methoxyphenol have been studied by LKB 2107 batch microcalorimetry system. Thermodynamic parameters Δ rH m , Δ G 0 , Δ G ≠ T ,) and kinetic parameters ( K m,k 2 ) have been determined. The process of the reaction has been analyzed from changes in energy by using the transition state theory. Two methods for enhancing catalytic power of Laccase are proposed. The results shown that formation of an enzyme substrate complex is“anticatalytic”. The enter and sole source of catalytic power is the stabilization of transition state; reactant state interactions are by nature inhibitory and only waste catalytic power.展开更多
olid state reactions of o-aminobenzoic acid (HOAB) with Cu (OAc)_2·H_2O,Cu(HCOO)_2 · 4H_2O, anhydrous Cu (OAc)_2 and Cu (HCOO)_2 at room or close toroom temperature have been investigated. The product Cu(OAB...olid state reactions of o-aminobenzoic acid (HOAB) with Cu (OAc)_2·H_2O,Cu(HCOO)_2 · 4H_2O, anhydrous Cu (OAc)_2 and Cu (HCOO)_2 at room or close toroom temperature have been investigated. The product Cu(OAB)_2 with a high yieldwas synthesized very conveniently compared witb the solution phase method. Thekinetic behavior was studied by means of the isothermal electrical conductivity mea-surement. The reactivity was found to decrease in the order : Cu(OAc)_2· H_2O>Cu(OAc)_2>Cu (HCOO)_2 ·4H_2O>Cu (HCOO)_2, which was attributable to the crystalstructures of the copper salts.展开更多
We study the two-dimensional weak-coupling Frohlich polaron in a completely anisotropic quantum dot in a perpendicular magnetic field. By performing a unitary transformation, we first transform the Hamiltonian into a ...We study the two-dimensional weak-coupling Frohlich polaron in a completely anisotropic quantum dot in a perpendicular magnetic field. By performing a unitary transformation, we first transform the Hamiltonian into a new one which describes an anisotropic harmonic oscillator with new mass and trapping frequencies interacting with the same phonon bath but with different interaction form and strength. Then employing the second-order Rayleigh–Schrodinger perturbation theory, we obtain the polaron correction to the ground-state energy. The magnetic field and anisotropic effects on the polaron correction to the ground-state energy are discussed.展开更多
The Fe(OH) 3 precursor was prepared by solid-state reaction with Fe(NO 3 ) 3 ·9H 2 O,NaOH and dispersed poly-ethylene glycol at low heating temperature(25℃).Synthesis of iron oxide(γ-Fe 2 O 3 )nanoparticle was ...The Fe(OH) 3 precursor was prepared by solid-state reaction with Fe(NO 3 ) 3 ·9H 2 O,NaOH and dispersed poly-ethylene glycol at low heating temperature(25℃).Synthesis of iron oxide(γ-Fe 2 O 3 )nanoparticle was achieved by thermal decomposition of Fe(OH) 3 ·xH 2 O precursor.The nanoparticle was characterized by TG-DTA,X-ray diffra-ction,TEM etc.The results showed that the nanoparticle was composed ofγ-Fe 2 O 3 and was a better absorber for electromagnetic wave within the low frequency band.展开更多
基金The support of the National Distinguished Young Investigator Fund(1996,29625410)is gratefully acknowledged
文摘It has been an established practice to estimate the Θ-temperature of a polymer solution from thedisappearance of the interchain interactions (A_2 = 0) Recently, in studies of the temperature dependence ofthe chain conformation in solution, we found that the change of the chain conformation clearly underwentthree different stages which could be viewed as the 'gas'. 'liquid' and 'solid' states in terms of the freedomof the 'blobs' on the chain. The transition temperature between the first and second stages corresponds nicelyto the Θ-temperature determined by the conventional method. It reveals, for the first time, that the Θ-temperature can be deduced from the conformation change of a single polymer chain in solution, which isimportant not only in conception, but also in practice.
基金the Nationa1 Natural Science Foundation(Grant No.49673185)the Ministry of Science and Technology of China(Grant No.95-Pre-39).
文摘Using the secondary spinel standard, the authors have precisely measured theFe^(3+)/SIGMA Fe values of spinels in mantle xenoliths from Cenozoic basalts in eastern China, andestimated the oxygen fugacities recorded by 63 mantle xenoliths through olivine-orthopyroxene-spineloxygen barometry. The results indicate that the oxygen fugacities of the lithospheric mantle ineastern China are higher in the south than in the north. Among them, the oxygen fugacity of theNorth China craton lithospheric mantle is the lowest, similar to that of the oceanic mantle, whilethat of Northeast and South China are the same as that of the global continental mantle. Thevariations of mantle redox state in eastern China are mainly controlled by the C-O-H fluids derivedfrom the asthenospheric mantle. According to the mantle oxidation state, it can be concluded thatthe C-O-H fluids in the lithospheric mantle of eastern China consist mainly of CO_2 and minor H_2O,but CH_4-rich fluids should come from the asthenosphere where the oxidation state is lower.
文摘The reaction between Laccase and o methoxyphenol have been studied by LKB 2107 batch microcalorimetry system. Thermodynamic parameters Δ rH m , Δ G 0 , Δ G ≠ T ,) and kinetic parameters ( K m,k 2 ) have been determined. The process of the reaction has been analyzed from changes in energy by using the transition state theory. Two methods for enhancing catalytic power of Laccase are proposed. The results shown that formation of an enzyme substrate complex is“anticatalytic”. The enter and sole source of catalytic power is the stabilization of transition state; reactant state interactions are by nature inhibitory and only waste catalytic power.
文摘olid state reactions of o-aminobenzoic acid (HOAB) with Cu (OAc)_2·H_2O,Cu(HCOO)_2 · 4H_2O, anhydrous Cu (OAc)_2 and Cu (HCOO)_2 at room or close toroom temperature have been investigated. The product Cu(OAB)_2 with a high yieldwas synthesized very conveniently compared witb the solution phase method. Thekinetic behavior was studied by means of the isothermal electrical conductivity mea-surement. The reactivity was found to decrease in the order : Cu(OAc)_2· H_2O>Cu(OAc)_2>Cu (HCOO)_2 ·4H_2O>Cu (HCOO)_2, which was attributable to the crystalstructures of the copper salts.
基金Project supported by the National Natural Science Foundation of China(Grant No.11375090)the K.C.Wong Magna Foundation in Ningbo University,China
文摘We study the two-dimensional weak-coupling Frohlich polaron in a completely anisotropic quantum dot in a perpendicular magnetic field. By performing a unitary transformation, we first transform the Hamiltonian into a new one which describes an anisotropic harmonic oscillator with new mass and trapping frequencies interacting with the same phonon bath but with different interaction form and strength. Then employing the second-order Rayleigh–Schrodinger perturbation theory, we obtain the polaron correction to the ground-state energy. The magnetic field and anisotropic effects on the polaron correction to the ground-state energy are discussed.
文摘The Fe(OH) 3 precursor was prepared by solid-state reaction with Fe(NO 3 ) 3 ·9H 2 O,NaOH and dispersed poly-ethylene glycol at low heating temperature(25℃).Synthesis of iron oxide(γ-Fe 2 O 3 )nanoparticle was achieved by thermal decomposition of Fe(OH) 3 ·xH 2 O precursor.The nanoparticle was characterized by TG-DTA,X-ray diffra-ction,TEM etc.The results showed that the nanoparticle was composed ofγ-Fe 2 O 3 and was a better absorber for electromagnetic wave within the low frequency band.
