Nano-scale CuF_(2) with superior electrochemical activity was successfully prepared by a mixed solvent co-precipitation method.The SEM and TEM analyses demonstrated that the methanol concentration had a pronounced eff...Nano-scale CuF_(2) with superior electrochemical activity was successfully prepared by a mixed solvent co-precipitation method.The SEM and TEM analyses demonstrated that the methanol concentration had a pronounced effect on both the particle size and the extent of agglomeration.With the increase in methanol content,the particle size and agglomeration of CuF_(2) decreased first and then increased.When the volume ratio of methanol to deionized water was 1:1,the CuF_(2) particles exhibited the smallest size and the lowest degree of agglomeration.CuF_(2) synthesized with 50%methanol exhibited superior electrochemical performances with a voltage plateau above 3 V and a 1st discharge capacity of 525.8 mAh·g^(-1) at 0.01 C due to the synergistic influence of the particle size and dispersion.The analysis results using electrochemical impedance spectroscopy(EIS)and constant current intermittent titration technique(GITT)affirmed the addition of methanol was beneficial for promoting Li+diffusion and accelerating electrochemical reaction kinetics of CuF_(2).展开更多
The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereeva...The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.展开更多
A Pt-Rh three-way catalyst（M-DS） supported on CeO_2-ZrO_2-La_2O_3-Nd_2O_3 and its analogous supported catalyst（DS） were developed via a modified double-solvent method and conventional double-solvent method, respec...A Pt-Rh three-way catalyst（M-DS） supported on CeO_2-ZrO_2-La_2O_3-Nd_2O_3 and its analogous supported catalyst（DS） were developed via a modified double-solvent method and conventional double-solvent method, respectively. The as-prepared catalysts were characterized by N_2 adsorption-desorption, X-ray diffraction（XRD）, CO-chemisorption, X-ray photoelectron spectroscopy（XPS） and hydrogen temperature-programmed reduction（H_2-TPR）. The preformed Pt nanoparticles generated using ethanol as a reducing agent on M-DS presented enhanced Pt dispersion regardless of aging treatment as confirmed by XRD and CO-chemisorption measurements. The textural properties and reduction ability of M-DS were maintained to a large extent after aging treatment. This result was consistent with those of the N_2 adsorption-desorption and H_2-TPR, respectively. Meanwhile, the XPS analysis demonstrated that higher Pt^0 species and larger Ce^（3＋） concentration could be obtained for M-DS. In the conversion of a simulated compressed natural gas（CNG） vehicle exhaust, both fresh and aged M-DS showed a significant enhancement in the activity and N_2-selectivity. Particularly, the complete conversion temperature（T_（90）） of CH_4 over the aged M-DS catalyst was 65 oC lower than that over the aged catalyst by conventional double-solvent method.展开更多
The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using ...The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using aluminum tri-sec-butoxide and zirconium n-propoxide as precursors. Ethanol (EtOH), isopropanol (iPrOH) and isobutanol (iBuOH) were used as solvents. The Al2O3-ZrO2 powders were characterized by nitrogen physisorption (SBET), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Prepared oxides calcined at 700℃ showed high specific surface area (200 - 240 m2/g). Obtained results suggest that the homogeneity of the mixed oxides is favored by using a water addition rate of 0.06 and 0.10 mL/min with ethanol as solvent.展开更多
An O / W emulsion non-solvent addition method was used to prepare ethyleellulose (EC) microcapsules of water soluble pharmaceutical (theophylline). The solvent and non-solvent reagents used in this work were toluene a...An O / W emulsion non-solvent addition method was used to prepare ethyleellulose (EC) microcapsules of water soluble pharmaceutical (theophylline). The solvent and non-solvent reagents used in this work were toluene and cyclohexane. The effects of polymer concentration, core wall ratio and particle size on the kinetics as well as the dissolution rate of the drug were investigated. The results show that the dissolution rate increases with the increasing of polymer concentration and core wall ratio. The release of microcapsules prepared with different procedures can be selectively profiled with first order and Higuchi matrix kinetic models.展开更多
In this study we used the deep eutectic solvents (ionic liquids) to investigate the reaction between copper (II) with ethylene diamine (en). Two of the existing methods for analyzing spectrophotometric measurements ha...In this study we used the deep eutectic solvents (ionic liquids) to investigate the reaction between copper (II) with ethylene diamine (en). Two of the existing methods for analyzing spectrophotometric measurements have been applied for establishing, the stoichiometry and whenever possible, the stability constants of the chelates formed. The method of continuous variations was necessary to determine first whether, the metal ion and the ligand ethylene diamine form one or more than one chelate, when more than one chelate formed, the results obtained depend on the wavelength and for meaningful conclusions the wavelengths were carefully selected. The empirical formulae of the chelates were further substantiated by the molar ratio method. The effect of time and temperature on the formation and stability of these chelates in solution is also studied. The stability constants, K1 and K2 for the copper (II) chelates were calculated, though reliable, and are comparable to literature values.展开更多
文摘Nano-scale CuF_(2) with superior electrochemical activity was successfully prepared by a mixed solvent co-precipitation method.The SEM and TEM analyses demonstrated that the methanol concentration had a pronounced effect on both the particle size and the extent of agglomeration.With the increase in methanol content,the particle size and agglomeration of CuF_(2) decreased first and then increased.When the volume ratio of methanol to deionized water was 1:1,the CuF_(2) particles exhibited the smallest size and the lowest degree of agglomeration.CuF_(2) synthesized with 50%methanol exhibited superior electrochemical performances with a voltage plateau above 3 V and a 1st discharge capacity of 525.8 mAh·g^(-1) at 0.01 C due to the synergistic influence of the particle size and dispersion.The analysis results using electrochemical impedance spectroscopy(EIS)and constant current intermittent titration technique(GITT)affirmed the addition of methanol was beneficial for promoting Li+diffusion and accelerating electrochemical reaction kinetics of CuF_(2).
基金Project ( 2001AA218011) supported by the National High Technology Development "863" Program of China
文摘The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.
基金supported by the National Key Research and Development Program of China(2016YFC0204902)
文摘A Pt-Rh three-way catalyst（M-DS） supported on CeO_2-ZrO_2-La_2O_3-Nd_2O_3 and its analogous supported catalyst（DS） were developed via a modified double-solvent method and conventional double-solvent method, respectively. The as-prepared catalysts were characterized by N_2 adsorption-desorption, X-ray diffraction（XRD）, CO-chemisorption, X-ray photoelectron spectroscopy（XPS） and hydrogen temperature-programmed reduction（H_2-TPR）. The preformed Pt nanoparticles generated using ethanol as a reducing agent on M-DS presented enhanced Pt dispersion regardless of aging treatment as confirmed by XRD and CO-chemisorption measurements. The textural properties and reduction ability of M-DS were maintained to a large extent after aging treatment. This result was consistent with those of the N_2 adsorption-desorption and H_2-TPR, respectively. Meanwhile, the XPS analysis demonstrated that higher Pt^0 species and larger Ce^（3＋） concentration could be obtained for M-DS. In the conversion of a simulated compressed natural gas（CNG） vehicle exhaust, both fresh and aged M-DS showed a significant enhancement in the activity and N_2-selectivity. Particularly, the complete conversion temperature（T_（90）） of CH_4 over the aged M-DS catalyst was 65 oC lower than that over the aged catalyst by conventional double-solvent method.
文摘The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using aluminum tri-sec-butoxide and zirconium n-propoxide as precursors. Ethanol (EtOH), isopropanol (iPrOH) and isobutanol (iBuOH) were used as solvents. The Al2O3-ZrO2 powders were characterized by nitrogen physisorption (SBET), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Prepared oxides calcined at 700℃ showed high specific surface area (200 - 240 m2/g). Obtained results suggest that the homogeneity of the mixed oxides is favored by using a water addition rate of 0.06 and 0.10 mL/min with ethanol as solvent.
文摘An O / W emulsion non-solvent addition method was used to prepare ethyleellulose (EC) microcapsules of water soluble pharmaceutical (theophylline). The solvent and non-solvent reagents used in this work were toluene and cyclohexane. The effects of polymer concentration, core wall ratio and particle size on the kinetics as well as the dissolution rate of the drug were investigated. The results show that the dissolution rate increases with the increasing of polymer concentration and core wall ratio. The release of microcapsules prepared with different procedures can be selectively profiled with first order and Higuchi matrix kinetic models.
文摘In this study we used the deep eutectic solvents (ionic liquids) to investigate the reaction between copper (II) with ethylene diamine (en). Two of the existing methods for analyzing spectrophotometric measurements have been applied for establishing, the stoichiometry and whenever possible, the stability constants of the chelates formed. The method of continuous variations was necessary to determine first whether, the metal ion and the ligand ethylene diamine form one or more than one chelate, when more than one chelate formed, the results obtained depend on the wavelength and for meaningful conclusions the wavelengths were carefully selected. The empirical formulae of the chelates were further substantiated by the molar ratio method. The effect of time and temperature on the formation and stability of these chelates in solution is also studied. The stability constants, K1 and K2 for the copper (II) chelates were calculated, though reliable, and are comparable to literature values.
