LiMn_(0.5)Fe_(0.5)PO_(4) has attracted great interest due to its good electrochemical performance and higher operating voltages.This has led to a greater than 30 percent higher energy density than for commercial Li Fe...LiMn_(0.5)Fe_(0.5)PO_(4) has attracted great interest due to its good electrochemical performance and higher operating voltages.This has led to a greater than 30 percent higher energy density than for commercial Li Fe PO4 olivine cathodes.Understanding the phase transition behaviors and kinetics of this material will help researchers to design and develop next generation cathodes for Li-ion batteries.In this study,we investigated non-equilibrium phase transition behaviors in a LiMn_(0.5)Fe_(0.5)PO_(4) cathode material during charge–discharge processes by varying current rates(C-rates)using synchrotron in-situ X-ray techniques.These methods included wide angle X-ray scattering(in-situ WAXS)and X-ray absorption spectroscopy(in-situ XAS).The WAXS spectra indicate that the phase transition of LiMn_(0.5)Fe_(0.5)PO_(4) material at slow C-rates is induced by a two-phase reaction.In contrast,at a high C-rate(5 C),the formation of an intermediate phase upon discharge is clearly observed.Concurrently,the oxidation numbers of the redox reactions of Fe^(2+)/Fe^(3+)and Mn^(2+)/Mn^(3+)were evaluated using in-situ XAS.This combination of synchrotron in-situ X-ray techniques gives clear insights into the non-equilibrium phase transition behavior of a LiMn_(0.5)Fe_(0.5)PO_(4) cathode material.This new understanding will be useful for further developments of this highly promising cathode material for practical commercialization.展开更多
Manganese-doped zinc silicate powder samples were prepared successfully by solution combustion process,and their photoluminescence were investigated in ultraviolet region. The single-phase of Zn_(2- x )SiO_4: x Mn (0...Manganese-doped zinc silicate powder samples were prepared successfully by solution combustion process,and their photoluminescence were investigated in ultraviolet region. The single-phase of Zn_(2- x )SiO_4: x Mn (0≤ x ≤0.10,willemite) was obtained by combustion synthesis at 600 ℃ for afew minutes,then heat treated at above 900 ℃ for 4 h. In the excitation spectra of Zn_(2- x )SiO_4: x Mn (0< x ≤0.10),the strongest broad band at about 254 nm is observed and assigned to (() 6A_1)→(() 4T_1) transition of Mn (2+) monitoring at 525 nm emission. At about 525 nm,the intense broad band emission is observed under 254 nm excitation in Zn_(2- x )SiO_4: x Mn (0< x ≤0.10). This broad band is attributed to (() 4T_1)→(() 6A_1) transition of Mn (2+). The results indicate that photoluminescence efficiency,the location of the strongest excitation or emission band,and the optimum concentration of activator depend on starting materials,combustion temperatures,the dosage of fuels,and the size of powder samples etc..展开更多
A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under th...A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under the influence of tidal currents, wind driven currents, and turbulent eddies is simulated by the PLUME RW dispersion model developed by HR Wallingford. The weathering processes in the model represent physical and chemical changes of soil slicks with time, and comprise mechanical spreading, dispersion, evaporation and emulsification. Shoreline stranding is determined approximately using a capacity method for different shoreline types. This paper presents details of the model, and describe the results of various sensitivity tests. The model is suitable for oil spill contingency planning.展开更多
In this paper, the capacity titration technique （CT technique） was developed on basis of the RPG （ratio of potentio-charge capacity to galvano-charge capacity） method to continuously determine the solid diffusion ...In this paper, the capacity titration technique （CT technique） was developed on basis of the RPG （ratio of potentio-charge capacity to galvano-charge capacity） method to continuously determine the solid diffusion coefficient D of the intercalary species within insertion-host materials with a small voltage region. The linear equations of D vs. q （value of ratio of the potentio-charge capacity to the galvano-charge capacity） were given in different range of q. By the CT technique,the Li^＋ solid diffusion coefficients D within LiMn2O4 at different voltages were determined. The results showed that the values of D varied from 3.447×10^-9 cm^2/s to 7.60×10^-11 cm^2/s in the voltage range of charge from 3.3V to 4.3V as a function of voltage with “W” shape.展开更多
[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea ext...[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea extract in cigarettes was studied.[Results]①In the experimental range,the best sensory evaluation effect of formula oolong tea extract was obtained with extraction conditions of 70%ethanol as extraction solvent,extraction time h,extraction temperature 25℃,and ultrasonic frequency 80 kHz,and follow-up low-temperature concentration,low-temperature sedimentation and low-temperature centrifugation.②The effects of different centrifugal speeds on the quality of formula oolong tea extract were explored.The formula oolong tea extract obtained under the conditions of 3000 r/min and centrifugal time of 10 min showed the best evaluation effect with soft and delicate smoke,rich smoke fragrance,good comfort and refreshing mouthfeel.③The effective aroma components in the formula oolong tea extract were qualitatively analyzed by GC-MS.[Conclusions]This study provides high-quality raw materials and a theoretical basis for the research of independent flavor blending in cigarette industry enterprises.展开更多
基金the Science Achievement Scholarship of Thailand(SAST)for financial supportpartially supported by the Institute of Nanomaterials Research and Innovation for Energy(IN-RIE)+1 种基金the Research and Graduate Studies,Khon Kaen University(KKU)Synchrotron Light Research Institute(SLRI),Thailand。
文摘LiMn_(0.5)Fe_(0.5)PO_(4) has attracted great interest due to its good electrochemical performance and higher operating voltages.This has led to a greater than 30 percent higher energy density than for commercial Li Fe PO4 olivine cathodes.Understanding the phase transition behaviors and kinetics of this material will help researchers to design and develop next generation cathodes for Li-ion batteries.In this study,we investigated non-equilibrium phase transition behaviors in a LiMn_(0.5)Fe_(0.5)PO_(4) cathode material during charge–discharge processes by varying current rates(C-rates)using synchrotron in-situ X-ray techniques.These methods included wide angle X-ray scattering(in-situ WAXS)and X-ray absorption spectroscopy(in-situ XAS).The WAXS spectra indicate that the phase transition of LiMn_(0.5)Fe_(0.5)PO_(4) material at slow C-rates is induced by a two-phase reaction.In contrast,at a high C-rate(5 C),the formation of an intermediate phase upon discharge is clearly observed.Concurrently,the oxidation numbers of the redox reactions of Fe^(2+)/Fe^(3+)and Mn^(2+)/Mn^(3+)were evaluated using in-situ XAS.This combination of synchrotron in-situ X-ray techniques gives clear insights into the non-equilibrium phase transition behavior of a LiMn_(0.5)Fe_(0.5)PO_(4) cathode material.This new understanding will be useful for further developments of this highly promising cathode material for practical commercialization.
文摘Manganese-doped zinc silicate powder samples were prepared successfully by solution combustion process,and their photoluminescence were investigated in ultraviolet region. The single-phase of Zn_(2- x )SiO_4: x Mn (0≤ x ≤0.10,willemite) was obtained by combustion synthesis at 600 ℃ for afew minutes,then heat treated at above 900 ℃ for 4 h. In the excitation spectra of Zn_(2- x )SiO_4: x Mn (0< x ≤0.10),the strongest broad band at about 254 nm is observed and assigned to (() 6A_1)→(() 4T_1) transition of Mn (2+) monitoring at 525 nm emission. At about 525 nm,the intense broad band emission is observed under 254 nm excitation in Zn_(2- x )SiO_4: x Mn (0< x ≤0.10). This broad band is attributed to (() 4T_1)→(() 6A_1) transition of Mn (2+). The results indicate that photoluminescence efficiency,the location of the strongest excitation or emission band,and the optimum concentration of activator depend on starting materials,combustion temperatures,the dosage of fuels,and the size of powder samples etc..
文摘A numerical model has been developed to simulate the transport and fate of oil spilled at sea. The model combines the transport and fate processes of spilled oil with the random walk technique. Oil movement under the influence of tidal currents, wind driven currents, and turbulent eddies is simulated by the PLUME RW dispersion model developed by HR Wallingford. The weathering processes in the model represent physical and chemical changes of soil slicks with time, and comprise mechanical spreading, dispersion, evaporation and emulsification. Shoreline stranding is determined approximately using a capacity method for different shoreline types. This paper presents details of the model, and describe the results of various sensitivity tests. The model is suitable for oil spill contingency planning.
基金This work was supported by NNSF of China(No.20406024)the Postdoctoral Science Foundation of Central South University(No.76600).
文摘In this paper, the capacity titration technique （CT technique） was developed on basis of the RPG （ratio of potentio-charge capacity to galvano-charge capacity） method to continuously determine the solid diffusion coefficient D of the intercalary species within insertion-host materials with a small voltage region. The linear equations of D vs. q （value of ratio of the potentio-charge capacity to the galvano-charge capacity） were given in different range of q. By the CT technique,the Li^＋ solid diffusion coefficients D within LiMn2O4 at different voltages were determined. The results showed that the values of D varied from 3.447×10^-9 cm^2/s to 7.60×10^-11 cm^2/s in the voltage range of charge from 3.3V to 4.3V as a function of voltage with “W” shape.
文摘[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea extract in cigarettes was studied.[Results]①In the experimental range,the best sensory evaluation effect of formula oolong tea extract was obtained with extraction conditions of 70%ethanol as extraction solvent,extraction time h,extraction temperature 25℃,and ultrasonic frequency 80 kHz,and follow-up low-temperature concentration,low-temperature sedimentation and low-temperature centrifugation.②The effects of different centrifugal speeds on the quality of formula oolong tea extract were explored.The formula oolong tea extract obtained under the conditions of 3000 r/min and centrifugal time of 10 min showed the best evaluation effect with soft and delicate smoke,rich smoke fragrance,good comfort and refreshing mouthfeel.③The effective aroma components in the formula oolong tea extract were qualitatively analyzed by GC-MS.[Conclusions]This study provides high-quality raw materials and a theoretical basis for the research of independent flavor blending in cigarette industry enterprises.
