The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the Ca...The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics.展开更多
The aim of this work was to develop, optimize and characterize a silymarin-laden polyvinylpyrrolidone(PVP)-polyethylene glycol(PEG) polymeric composite to resolve low aqueous solubility and dissolution rate problem of...The aim of this work was to develop, optimize and characterize a silymarin-laden polyvinylpyrrolidone(PVP)-polyethylene glycol(PEG) polymeric composite to resolve low aqueous solubility and dissolution rate problem of the drug. A number of silymarin-laden polymeric formulations were fabricated with different quantities of PVP K-30 and PEG 6000 by the solvent-evaporation method. The effect of PVP K-30 and PEG 6000 on the aqueous solubility and dissolution rate was investigated. The optimized formulation and its constituents were characterized using powder X-ray diffraction(PXRD), differential scanning calorimetry(DSC), scanning electron microscopy(SEM) and Fourier transform infrared spectroscopy(FTIR) techniques. Both the PEG 6000 and PVP K-30 positively affected the aqueous solubility and dissolution rate of the drug. In particular, a formulation consisting of silymarin, PVP K-30 and PEG 6000(0.25/1.5/1.5, w/w/w) furnished the highest solubility(24.3972.95 mg/mL) and an excellent dissolution profile( $100% in 40 min). The solubility enhancement with this formulation was $ 1150-fold as compared to plain silymarin powder. Moreover, all the constituents existed in the amorphous state in this silymarin-laden PVP-PEG polymeric composite. Accordingly, this formulation might be a promising tool to administer silymarin with an enhanced effect via the oral route.展开更多
Aim To study the effect of complexation with hydroxylpmpyl-β-cycledextrin (HP-β-CD) on the solubility, dissolution rate and chemical stability of pmstaglandin E1 (PGE1), thereby providing a basis for preparing a sta...Aim To study the effect of complexation with hydroxylpmpyl-β-cycledextrin (HP-β-CD) on the solubility, dissolution rate and chemical stability of pmstaglandin E1 (PGE1), thereby providing a basis for preparing a stable solid or aqueous preparation of PGF1 formulated with HP-β-CD. Methods The effect of HP-β-CD on the solubility of PGF1 was studied by phase solubility method. The formation of inclusion complexes of PGE1 with HP-β-CD in the aqueous solution was confirmed by UV spectra, circular dichroism spectroscopy, and that in the solid state by IR spectra and X-ray diffractometry. An solid inclusion complex of PGF1 with HP-β-CD was prepared by lyophilization. The dissolution rate and stability of the inclusion complex were determined and compared with those of PGE1 alone. Meanwhile, the stability of PGF1 aqueous solutions in the presence of HP-β-CD was studied under different pH conditions. Results The solubility of PGF1 increased linearly with increasing HP-β-CD concentration in various pH buffered solutions, showing typical AL-type phase solubility diagrams. The stability and dissolution rate of the solid inclusion complex of PGE1 were significantly increased, compared with those of pure PGE1 . The stability of PGEI in HP-β-CD solutions was also obviously improved under acidic and basic conditions, but the stabilizing effect was absent under neutral conditions. Conclulsions The solubility, dissolution rate and chemical stability of PGE1 are markedly improved by complexation with HP-β-CD. It is quite possible to prepare a stable PGE1 inclusion complex-containing solid dosage forms, but almost impossible to obtain a stable aqueous preparation of PGE1 formulated with HP-β-CD.展开更多
Carbamazepine(CBZ)is an anticonvulsant with very low water solubility,presenting as a white crystalline powder with poor mechanical properties and is hard to bend.To enhance CBZ's physicochemical properties,such a...Carbamazepine(CBZ)is an anticonvulsant with very low water solubility,presenting as a white crystalline powder with poor mechanical properties and is hard to bend.To enhance CBZ's physicochemical properties,such as water solubility and mechanical properties,we selected six cocrystal coformers(CCFs):nicotinamide(NIC),benzamide(BZM),salicylic acid(SCA),fumaric acid(FMA),trimesic acid(TMA),and hesperetin(HPE).Six CBZ cocrystals were successfully prepared using the solution method.Fourier transform infrared spectroscopy(FT-IR),powder X-ray diffraction(PXRD),differential scanning calorimetry(DSC),and single crystal X-ray diffraction(SCXRD)were used to characterize the crystal structures and gain comprehensive insights into the six cocrystals.The mechanical,fluorescence,and solubility properties of the six cocrystals were tested.The results reveal that most of the prepared cocrystals exhibit improved water solubility and mechanical properties when compared to CBZ.Among them,the dissolution rate of cocrystals excluded from CBZ-HPE has increased by an average of 3 or 4 times compared to CBZ,while CBZ-HPE exhibits superior mechanical properties.Moreover,all six cocrystals possess better fluorescence performance than CBZ.We thoroughly evaluated the mechanical properties of the cocrystals through both experimental and theoretical approaches.This work provides a new direction for studying drug cocrystals to improve the physicochemical properties of drugs.展开更多
The calcite dissolution rates at 50-250 ℃ and 20 MPa in deionized water with flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. Equilibrium concen...The calcite dissolution rates at 50-250 ℃ and 20 MPa in deionized water with flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. Equilibrium concentration (Ceq) of calcite dissolution in deionized water at 20 MPa was determined using dissolution data according to the iterative method presented by Jeschke and Dreybrodt. The equilibrium concentrations at 50, 100, 150, 200 and 250 ℃ are 1.84×10^-4, 2.23×10^-4, 2.25×10^-4, 2.31×10^-4 and 2.24×10^-4 mol/L, respectively. The Ceq increases first and then decreases with temperature varying from 50 to 250 ℃ at 20 MPa, and the same variation trend occurs at 10 MPa with lower values. The maximum value (or extremum) of Ceq would increase with temperature at constant pressures. The dissolution reaction of calcite in this experiment is approaching the calcite equilibrium, and the reaction order doesn't keep a constant at different temperatures, which could imply that a change of the reac- tion mechanism was occurring. The Arrhenius equation shouldn't be used to calculate apparent activation energy using rate constant data at different temperatures when the reaction order or reaction mechanism changed.展开更多
Research on karst processes is important for the determination of their carbon sink potential,as is research into terrestrial ecosystems in karst areas.Solutional denudation rates of soils from three karst spring wate...Research on karst processes is important for the determination of their carbon sink potential,as is research into terrestrial ecosystems in karst areas.Solutional denudation rates of soils from three karst spring watersheds supporting different land uses were studied.Solution rates showed a distinct pattern based on land use,with a generally higher rate being recorded in forest use soil.The mean values for tablet dissolution from the cultivated land,shrublands,secondary forest,grassland and primary forest were 4.02,7.0,40.0,20.0,63.5 t km-2 a-1 respectively.Changes in vegetation patterns could improve the size of karst carbon sinks;for example,in this study the carbon sink was 3 times higher in primary forest than in secondary forest soil and 9 times higher than under shrubland,equating to an increase from 5.71-7.02 to 24.86-26.17 t km-2 a-1 from cultivated land or shrub to secondary forest and to primary forest,respectively.展开更多
Determination of dissolution rate of alumina is one of the classical problems in aluminum electrolysis.A novel method which can measure the dissolution rate of alumina was presented.Effect of factors on dissolution ra...Determination of dissolution rate of alumina is one of the classical problems in aluminum electrolysis.A novel method which can measure the dissolution rate of alumina was presented.Effect of factors on dissolution rate of alumina was studied intuitively and roundly using transparent quartz electrobath and image analysis techniques.Images about dissolution process of alumina were taken at an interval of fixed time from transparent quartz electrobath of double rooms.Gabor wavelet transforms were used for extracting and describing the texture features of each image.After subsampling several times,the dissolution rate of alumina was computed using these texture features in local neighborhood of samples.Regression equation of the dissolution rate of alumina was obtained using these dissolution rates.Experiments show that the regression equation of the dissolution rate of alumina is y=-0.000 5x3+0.024 0x2-0.287 3x+ 1.276 7 for Na3AlF6-AlF3-Al2O3-CaF2-LiF-MgF2 system at 920 °C.展开更多
基金supported by the National Natural Science Foundation of China(52272022)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(2019ZYYD076)the Innovation and Entrepreneurship Fund of Wuhan University of Science and Technology(D202202171045002669).
文摘The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics.
文摘The aim of this work was to develop, optimize and characterize a silymarin-laden polyvinylpyrrolidone(PVP)-polyethylene glycol(PEG) polymeric composite to resolve low aqueous solubility and dissolution rate problem of the drug. A number of silymarin-laden polymeric formulations were fabricated with different quantities of PVP K-30 and PEG 6000 by the solvent-evaporation method. The effect of PVP K-30 and PEG 6000 on the aqueous solubility and dissolution rate was investigated. The optimized formulation and its constituents were characterized using powder X-ray diffraction(PXRD), differential scanning calorimetry(DSC), scanning electron microscopy(SEM) and Fourier transform infrared spectroscopy(FTIR) techniques. Both the PEG 6000 and PVP K-30 positively affected the aqueous solubility and dissolution rate of the drug. In particular, a formulation consisting of silymarin, PVP K-30 and PEG 6000(0.25/1.5/1.5, w/w/w) furnished the highest solubility(24.3972.95 mg/mL) and an excellent dissolution profile( $100% in 40 min). The solubility enhancement with this formulation was $ 1150-fold as compared to plain silymarin powder. Moreover, all the constituents existed in the amorphous state in this silymarin-laden PVP-PEG polymeric composite. Accordingly, this formulation might be a promising tool to administer silymarin with an enhanced effect via the oral route.
文摘Aim To study the effect of complexation with hydroxylpmpyl-β-cycledextrin (HP-β-CD) on the solubility, dissolution rate and chemical stability of pmstaglandin E1 (PGE1), thereby providing a basis for preparing a stable solid or aqueous preparation of PGF1 formulated with HP-β-CD. Methods The effect of HP-β-CD on the solubility of PGF1 was studied by phase solubility method. The formation of inclusion complexes of PGE1 with HP-β-CD in the aqueous solution was confirmed by UV spectra, circular dichroism spectroscopy, and that in the solid state by IR spectra and X-ray diffractometry. An solid inclusion complex of PGF1 with HP-β-CD was prepared by lyophilization. The dissolution rate and stability of the inclusion complex were determined and compared with those of PGE1 alone. Meanwhile, the stability of PGF1 aqueous solutions in the presence of HP-β-CD was studied under different pH conditions. Results The solubility of PGF1 increased linearly with increasing HP-β-CD concentration in various pH buffered solutions, showing typical AL-type phase solubility diagrams. The stability and dissolution rate of the solid inclusion complex of PGE1 were significantly increased, compared with those of pure PGE1 . The stability of PGEI in HP-β-CD solutions was also obviously improved under acidic and basic conditions, but the stabilizing effect was absent under neutral conditions. Conclulsions The solubility, dissolution rate and chemical stability of PGE1 are markedly improved by complexation with HP-β-CD. It is quite possible to prepare a stable PGE1 inclusion complex-containing solid dosage forms, but almost impossible to obtain a stable aqueous preparation of PGE1 formulated with HP-β-CD.
基金National Natural Science Foundation of China(grant No.22068002 and 22178054)Training plan for academic and technical leaders of major disciplines in Jiangxi Province-Youth Talent Project(grant No.20212BCj23001)+1 种基金Jiangxi Provincial Natural Science Foundation(grant No.20224ACB213007,20212ACB203002,and 20232BBH80015)Jiangxi Province Key Laboratory of Synthetic Chemistry(grant No.JXSC202209).
文摘Carbamazepine(CBZ)is an anticonvulsant with very low water solubility,presenting as a white crystalline powder with poor mechanical properties and is hard to bend.To enhance CBZ's physicochemical properties,such as water solubility and mechanical properties,we selected six cocrystal coformers(CCFs):nicotinamide(NIC),benzamide(BZM),salicylic acid(SCA),fumaric acid(FMA),trimesic acid(TMA),and hesperetin(HPE).Six CBZ cocrystals were successfully prepared using the solution method.Fourier transform infrared spectroscopy(FT-IR),powder X-ray diffraction(PXRD),differential scanning calorimetry(DSC),and single crystal X-ray diffraction(SCXRD)were used to characterize the crystal structures and gain comprehensive insights into the six cocrystals.The mechanical,fluorescence,and solubility properties of the six cocrystals were tested.The results reveal that most of the prepared cocrystals exhibit improved water solubility and mechanical properties when compared to CBZ.Among them,the dissolution rate of cocrystals excluded from CBZ-HPE has increased by an average of 3 or 4 times compared to CBZ,while CBZ-HPE exhibits superior mechanical properties.Moreover,all six cocrystals possess better fluorescence performance than CBZ.We thoroughly evaluated the mechanical properties of the cocrystals through both experimental and theoretical approaches.This work provides a new direction for studying drug cocrystals to improve the physicochemical properties of drugs.
基金supported by the National Basic Research Program of China (973 Program) (No. 2009CB421006)the State Key Laboratory of Geological Processes and Mineral Resources (No. GPMR200843)
文摘The calcite dissolution rates at 50-250 ℃ and 20 MPa in deionized water with flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. Equilibrium concentration (Ceq) of calcite dissolution in deionized water at 20 MPa was determined using dissolution data according to the iterative method presented by Jeschke and Dreybrodt. The equilibrium concentrations at 50, 100, 150, 200 and 250 ℃ are 1.84×10^-4, 2.23×10^-4, 2.25×10^-4, 2.31×10^-4 and 2.24×10^-4 mol/L, respectively. The Ceq increases first and then decreases with temperature varying from 50 to 250 ℃ at 20 MPa, and the same variation trend occurs at 10 MPa with lower values. The maximum value (or extremum) of Ceq would increase with temperature at constant pressures. The dissolution reaction of calcite in this experiment is approaching the calcite equilibrium, and the reaction order doesn't keep a constant at different temperatures, which could imply that a change of the reac- tion mechanism was occurring. The Arrhenius equation shouldn't be used to calculate apparent activation energy using rate constant data at different temperatures when the reaction order or reaction mechanism changed.
基金supported by the National Natural Science Foundation of China (40772164)the Special Fund for Public Benefit Scientific Research of Ministry of Land and Resources of China (201111022)the China Geological Survey Project (1212010911062 and water-2010030701)
文摘Research on karst processes is important for the determination of their carbon sink potential,as is research into terrestrial ecosystems in karst areas.Solutional denudation rates of soils from three karst spring watersheds supporting different land uses were studied.Solution rates showed a distinct pattern based on land use,with a generally higher rate being recorded in forest use soil.The mean values for tablet dissolution from the cultivated land,shrublands,secondary forest,grassland and primary forest were 4.02,7.0,40.0,20.0,63.5 t km-2 a-1 respectively.Changes in vegetation patterns could improve the size of karst carbon sinks;for example,in this study the carbon sink was 3 times higher in primary forest than in secondary forest soil and 9 times higher than under shrubland,equating to an increase from 5.71-7.02 to 24.86-26.17 t km-2 a-1 from cultivated land or shrub to secondary forest and to primary forest,respectively.
基金Projects(51101104,51072121) supported by the National Natural Science Foundation of ChinaProject(LS2010109) supported by the Key Laboratory Foundation of Liaoning Province,China
文摘Determination of dissolution rate of alumina is one of the classical problems in aluminum electrolysis.A novel method which can measure the dissolution rate of alumina was presented.Effect of factors on dissolution rate of alumina was studied intuitively and roundly using transparent quartz electrobath and image analysis techniques.Images about dissolution process of alumina were taken at an interval of fixed time from transparent quartz electrobath of double rooms.Gabor wavelet transforms were used for extracting and describing the texture features of each image.After subsampling several times,the dissolution rate of alumina was computed using these texture features in local neighborhood of samples.Regression equation of the dissolution rate of alumina was obtained using these dissolution rates.Experiments show that the regression equation of the dissolution rate of alumina is y=-0.000 5x3+0.024 0x2-0.287 3x+ 1.276 7 for Na3AlF6-AlF3-Al2O3-CaF2-LiF-MgF2 system at 920 °C.