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
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 ...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 5x^3＋0.024 0x^2-0.287 3x＋ 1.276 7 for Na3AIF6-AIF3-Al2O3-CaF2-LiF- MgF2 system at 920 ℃.展开更多
Aim To study the effect of complexation with hydroxylpropyl-β-cyclodextrin(HP-β-CD) on the solubility, dissolution rate and chemical stability of prostaglandin E_1 (PGE_1) ,thereby providing a basis for preparing a ...Aim To study the effect of complexation with hydroxylpropyl-β-cyclodextrin(HP-β-CD) on the solubility, dissolution rate and chemical stability of prostaglandin E_1 (PGE_1) ,thereby providing a basis for preparing a stable solid or aqueous preparation of PGE_1 formulatedwith HP-β-CD. Methods The effect of HP-β-CD on the solubility of PGE_1 was studied by phasesolubility method. The formation of inclusion complexes of PGE_1 with HP-β-CD in the aqueoussolution was confirmed by UV spectra, circular dichroism spectroscopy, and that in the solid stateby IR spectra and X-ray diffractome-try. An solid inclusion complex of PGE_1 with HP-β-CD wasprepared by lyophilization. The dissolution rate and stability of the inclusion complex weredetermined and compared with those of PGE_1 alone. Meanwhile, the stability of PGE_1 aqueoussolutions in the presence of HP-β-CD was studied under different pH conditions. Results Thesolubility of PGE_1 increased linearly with increasing HP-β-CD concentration in various pH bufferedsolutions, showing typical A_L-type phase solubility diagrams. The stability and dissolution rateof the solid inclusion complex of PGE_1 were significantly increased, compared with those of purePGE_1 . The stability of PGE_1 in HP-β-CD solutions was also obviously improved under acidic andbasic conditions, but the stabilizing effect was absent under neutral conditions. Conclusions Thesolubility,dissolution rate and chemical stability of PGE_1 are markedly improved by complexationwith HP-β-CD: It is quite possible to prepare a stable PGE_1 inclusion complex-containing soliddosage forms, but almost impossible to obtain a stable aqueous preparation of PGE_1 formulated withHP-β-CD.展开更多
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 effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolutio...The effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolution rate in hydrophilic surfactants such as tween 80 and sodium lauryl sulfate （SLS）. Differential scanning calorimetry （DSC） and Fourier transform infrared spectroscopy （FT-IR） indicated the existence of both form Ⅰ and Ⅱ ofprednisolone in SLS treated crystals. The FT-IR results also showed that, only form Ⅱ could be detected in prednisolone crystals without surfactant and prednisolone form Ⅲ was produced in tween 80 treated crystals. These results were also confirmed by X-ray （XRD） diffraction and scanning electron microscopy （SEM）. In general, the results indicated that the presence of hydrophilic surfactants could generate forms Ⅱ and Ⅲ of the crystals. These forms would give rlse to the increase of prednisolone＇s dissolution rate owing to their physicochemical instability and more hydrophilic property in comparison with stable polymorph of form Ⅰ.展开更多
Feldspar minerals are widely present in clastic reservoirs of hydrocarbon-bearing basins,where they undergo significant dissolution during burial processes.The dissolution kinetics and evolutionary trends of feldspar ...Feldspar minerals are widely present in clastic reservoirs of hydrocarbon-bearing basins,where they undergo significant dissolution during burial processes.The dissolution kinetics and evolutionary trends of feldspar under burial conditions are critical for the formation of secondary porosity and the evolution of reservoir spaces.The feldspar dissolution process is frequently associated with the precipitation and transformation of complex authigenic minerals,making it challenging to accurately determine dissolution rates under near-equilibrium conditions.This study performed experimental simulations of feldspar(K-feldspar and albite)dissolution under conditions ranging from far-from-equilibrium to near-equilibrium,with varying temperatures and pCO_(2).Under near-equilibrium conditions,scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),and laser confocal microscopy were employed to achieve accurate quantification of the dissolution volume of feldspar samples.The dissolution rates of feldspar under near-equilibrium conditions,along with the factors influencing these rates,were systematically investigated.The results indicate that the dissolution rates of K-feldspar under near-equilibrium conditions at temperatures and pCO_(2)levels of 80℃/1 bar,120℃/4.2 bar,and 160℃/17.9 bar are 2.16695×10^(15)–8.040×10^(15),4.49288×10^(15)–1.480×10^(14),and 6.17462×10^(15)–2.496×10^(14)mol cm^(-2)s^(-1),respectively.Under the same near-equilibrium conditions,the dissolution rates of albite are 2.93294×10^(15)–1.365×10^(14),5.54499×10^(15)–2.170×10^(14),and 9.42841×10^(15)–3.074×10^(14)mol cm^(-2)s^(-1),respectively.The dissolution rates of feldspar under near-equilibrium conditions are significantly lower(1.5–2orders of magnitude at high temperatures)than those under far-equilibrium conditions.Furthermore,as the temperature increases by a gradient of 40℃,the dissolution rate only increases by only 1.5 times,which is substantially lower than the rate increase observed under far-equilibrium conditions.The discrepancy between feldspar dissolution rates under far-equilibrium conditions(L-TST)and near-equilibrium conditions increases with rising temperature.Under identical experimental conditions,the dissolution rate of albite under near-equilibrium conditions is higher than that of K-feldspar.The precipitation and transformation of secondary minerals regulate feldspar dissolution under near-equilibrium conditions by altering ion concentrations in the solution.The p H of the solution also plays a significant role in controlling feldspar dissolution under near-equilibrium conditions.This study establishes a method for quantitatively analyzing mineral dissolution using the surface morphological features of dissolved and undissolved segments of polished feldspar samples.This method avoids relying on changes in ion concentrations in the reaction solution,making it more reasonable and widely applicable.Moreover,the results provide valuable insights into feldspar dissolution kinetics under burial conditions within closed systems,enabling a more accurate assessment of the contribution of feldspar dissolution to pore formation in reservoirs.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
Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-...Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-80 specifications：35mL/L 85% H3PO4＋20g/L CrO3 at 38℃.Influence of oxalic acid concentration,bath temperature and anodic current density on dissolution rate and coating ratio was examined,when the sulphuric acid concentration was maintained at 160g/L.It was found that chemically resistant and compact oxide layers were produced under low operational temperature （5℃） and high current densities （3A/dm^2）.A beneficial effect was observed concerning the addition of oxalic acid （18g/L）.The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy （SEM）,atomic force microscopy （AFM） and glow-discharge optical emission spectroscopy （GDOES）.展开更多
In order to clarify the dynamic process of feldspar dissolution-precipitation and explore the formation mechanism of secondary porosity,six batch reactor experiments were conducted at 200℃and pH=7 measured at room te...In order to clarify the dynamic process of feldspar dissolution-precipitation and explore the formation mechanism of secondary porosity,six batch reactor experiments were conducted at 200℃and pH=7 measured at room temperature.Temporal evolution of fluid chemistry was analyzed with an inductively coupled plasma optical emission spectrometer(ICP-OES).Solid reaction products were retrieved from six batch experiments terminated after 36,180,276,415,766 and 1008 h.Scanning electron microscopy(SEM)revealed dissolution features and significant secondary mineral adhered on the feldspar surface.The process of feldspar dissolution-precipitation proceeded slowly and full equilibrium was not achieved after 1008 h.Saturation indices suggested that the albite and K-feldspar dissolution occurred throughout the experiments.The average dissolution rates for albite and K-feldspar were 2.28×10^-10 and 8.51×10^-11 mol m^-2 s^-1,respectively.Based on the experimental data,the reaction process of alkaline feldspar was simulated and the secondary porosity had increased 0.3%after the experiment.展开更多
The dissolution performance of black aluminum dross(BAD)in cryolite electrolyte is key to its recovery by molten salt electrolysis.The stable operation of the electrolyzer depends mainly on the rapid dissolution of BA...The dissolution performance of black aluminum dross(BAD)in cryolite electrolyte is key to its recovery by molten salt electrolysis.The stable operation of the electrolyzer depends mainly on the rapid dissolution of BAD in Na_(3)AlF_(6)-AlF_(3)-Al_(2)O_(3)electrolyte system.In this paper,the dissolution performance and behavior of BAD and its main components in the cryolite system were studied,and the saturation solubility of aluminum nitride in this system was determined.The dissolution performance of BAD in cryolite electrolyte before and after denitration was compared,and the effects of temperature,cryolite ratio,and the doping ratio of BAD and alumina on the dissolution rate were investigated.The obtained results showed that aluminum nitride was the main factor affecting the dissolution performance of BAD in the electrolyte.Aluminum nitride was partly converted toα-Al_(2)O_(3)after addition to the electrolyte,and the convertedα-Al_(2)O_(3)was partially dissolved in the cryolite electrolyte,while the remaining precipitated and accumulated at the bottom with aluminum nitride.Aluminum nitride was almost insoluble in the cryolite electrolyte,with 0.0022%solubility.A higher proportion ofα-Al_(2)O_(3)in BAD was negatively influenced its solubility in the cryolite electrolyte.The dissolution rate of BAD in cryolite electrolytes was effectively improved by mixing BAD withγ-Al_(2)O_(3).展开更多
The dissolution behavior of delta ferrites in martensitic heat-resistant steel was studied.And the reason why the dissolution rate of delta ferrites decreased with dissolution time was discussed.The experimental resul...The dissolution behavior of delta ferrites in martensitic heat-resistant steel was studied.And the reason why the dissolution rate of delta ferrites decreased with dissolution time was discussed.The experimental results show that the chemical compositions of delta ferrites negligibly change with dissolution time.The decrease of dissolution rate of delta ferrites with dissolution time should be attributed to the change of shape and distribution of delta ferrites.The shape of delta ferrites tends to transfer from polygon to sphere with dissolution time,causing the decrease of specific surface area of delta ferrites.The distribution position of delta ferrites tends to transfer from boundaries of austenite grains to interior of austenite grains with dissolution time,decreasing the diffusion coefficient of alloy atoms.Both them decrease the dissolution rate of delta ferrites.展开更多
Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium ...Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.展开更多
Dissolution kinetics of sodium carbonate is investigated with the image analysis method at the approach of single particle.The dissolution experiments are carried out in an aqueous solution under a series of controlle...Dissolution kinetics of sodium carbonate is investigated with the image analysis method at the approach of single particle.The dissolution experiments are carried out in an aqueous solution under a series of controlled temperature and p H.The selected sodium carbonate particles are all spherical with the same mass and diameter.The dissolution process is quantified with the measurement of particle diameter from dissolution images.The concentration of dissolved sodium carbonate in solvent is calculated with the measured diameter of particle.Both surface reaction model and mass transport model are implemented to determine the dissolution mechanism and quantify the dissolution rate constant at each experimental condition.According to the fitting results with both two models,it is clarified that the dissolution process at the increasing temperature is controlled by the mass transport of dissolved sodium carbonate travelling from particle surface into solvent.The dissolution process at the increasing pH is controlled by the chemical reaction on particle surface.Furthermore,the dissolution rate constant for each single spherical sodium carbonate particle is quantified and the results show that the dissolution rate constant of single spherical sodium carbonate increases significantly with the rising of temperature,but decreases with the increasing of pH conversely.展开更多
Irbesartan(IBS)is a tetrazole derivative and antihypertensive drug that has two interconvertible structures,1H-and 2H-tautomers.The difference between them lies in the protonation of the tetrazole ring.In the solid-st...Irbesartan(IBS)is a tetrazole derivative and antihypertensive drug that has two interconvertible structures,1H-and 2H-tautomers.The difference between them lies in the protonation of the tetrazole ring.In the solid-state,both tautomers can be isolated as crystal forms A(1H-tautomer)and B(2H-tautomer).Studies have reported that IBS is a polymorphic system and its forms A and B are related monotropically.These reports indicate form B as the most stable and less soluble form.Therefore,the goal of this contribution is to demonstrate through a complete solid-state characterization,thermodynamic study and dissolution properties that the IBS forms are desmotropes that are not related monotropically.However,the intention is also to call attention to the importance of conducting strict chemical and in solid-state quality controls on the IBS raw materials.Hence,powder X-ray diffraction(PXRD)and Raman spectroscopy(RS)at ambient and non-ambient conditions,differential scanning calorimetry(DSC),hot stage microscopy(HSM),Fourier transform infrared(FT-IR)and scanning electron microscopy(SEM)techniques were applied.Furthermore,intrinsic dissolution rate(IDR)and structural stability studies at 98%relative humidity(RH),25℃and 40℃were conducted as well.The results show that in fact,form A is approximately four-fold more soluble than form B.In addition,both IBS forms are stable at ambient conditions.Nevertheless,structural and/or chemical instability was observed in form B at 40℃and 98%RH.IBS has been confirmed as a desmotropic system rather than a polymorphic one.Consequently,forms A and B are not related monotropically.展开更多
Carbon dissolution from four types of metallurgical cokes and graphite was investigated by using immersion rods in a resistance furnace to clarify the influence of factors governing the rate of carbon dissolution from...Carbon dissolution from four types of metallurgical cokes and graphite was investigated by using immersion rods in a resistance furnace to clarify the influence of factors governing the rate of carbon dissolution from carbonaceous materials into Fe-Mn melts at 1550℃.The factors studied were the nmicrostructure of carbonaceous materials,roughness,porosity and the wettability between carbonaceous materials and the melt.Carbon/metal in terface was characterised by sea nning electron microscopy accompanied with energy-dispersive X-ray spectrometry to investigate the form at io n of an ash layer.The results showed that coke E had the highest dissolution rate.Surface roughness and porosity of the carbonaceous materials seemed to be dominant factors affecting the dissolution rates.Further,crystallite size did not have a significant effect on the dissolution rates.Solid/liquid wettability seemed to affect the initial stage of dissolution reaction.The dissolution mechanism was found to be both mass transfer and interfacial reactions.展开更多
Inclusion complexation between ibuprofen (IBF) and βcyclodextrin (βCD) was investigated. Phase solubility studies of the complexation suggested the formation of a 1:3 complex and a 2:3 complex between IBF and βCD a...Inclusion complexation between ibuprofen (IBF) and βcyclodextrin (βCD) was investigated. Phase solubility studies of the complexation suggested the formation of a 1:3 complex and a 2:3 complex between IBF and βCD at room temperature (23℃) and at 37℃ respectively. Solid inclusion complexes were prepared by the homogeneous coprecipitation method. Scanning electron microscopy, differential scanning calorimetry, IR spectroscopy, and Xray diffractometry were used for the characterization and evaluation of the complexes. The solubility and dissolution rate of the complexes formed were found to have improved considerably over that of the physical mixture and the drug alone, indicating that βcyclodextrin played an important role in the solubilization of ibuprofen.展开更多
To validate the feasibility of using near-infrared(NIR)spectroscopy for real-time monitoring of multiple active pharmaceutical ingredients dissolution,this study focused on Guizhi Fuling capsules and tablets.The NIR s...To validate the feasibility of using near-infrared(NIR)spectroscopy for real-time monitoring of multiple active pharmaceutical ingredients dissolution,this study focused on Guizhi Fuling capsules and tablets.The NIR spectroscopy fiber probe was inserted into the dissolution apparatus and connected to a Fourier transform near-infrared spectrometer(FT-NIR)to capture spectral data.During the dissolution tests,dissolution behavior curves for seven components,gallic acid(GA),alibiflorin(ALI),paeoniflorin(PF),paeonol(PAE),amygdalin(AMY),cinnamaldehyde(CL),and cinnamic acid(CA)in the capsules,were obtained by sampling from the dissolution cups at specific time intervals.Linear regression was applied to models corrected using various pre-process techniques with the partial least squares(PLS)algorithm.Additionally,an artificial neural network(ANN),a nonlinear regression algorithm,was utilized to explore the complex relationship between spectra and multicomponent dissolution.Ultimately,the ANN model achieved a lower prediction mean square error(RMSEP)and relative error compared to the PLS model,with significantly higher correlation coefficient(Rp)for the validation set.The highest Rpvalue reached 0.8825.The paired t-test results also indicated no significant difference between predicted and measured values.Furthermore,the ANN model demonstrated the best predictive performance in the tablet experiments,achieving an Rpof 0.8134.The findings indicate that real-time monitoring of multicomponent drug dissolution using NIR spectroscopy combined with chemometric methods is feasible,offering a promising new direction to replace traditional dissolution testing.展开更多
AThe wastewater source of 4# tailing pond in Dexing copper mine consists of alkaline flotation pulp and acid mine drainage （AMD） from the nearby opencast mine. Therefore, the heavy metals in tailing ore are very lik...AThe wastewater source of 4# tailing pond in Dexing copper mine consists of alkaline flotation pulp and acid mine drainage （AMD） from the nearby opencast mine. Therefore, the heavy metals in tailing ore are very likely to be released due to acidification from AMD. The leaching behaviors ofZn, Cu, Fe and Mn in mine tailings from Dexing copper mine were investigated by a series of laboratory batch experiments. The effectcs ofpH, temperature, particle size and contact time on the leachability of such heavy metals were examined. It was evident that Zn, Cu, Fe and Mn were major heavy metals in the tailings while gangue minerals like quartz were major constituents in examined tailings. The tailing dissolution reaction was controlled by the acid, whose kinetics could be expressed according to the heterogeneous reaction models and explained by a shrinking core model with the surface chemical reaction as the rate-controlling step. The leachability of all metals examined depended on pH and contact time. The batch studies indicated that the maximum leaching ratios ofZn, Cu, Fe and Mn at pH 2.0 were 5.4%, 5.8%, l 1.1% and 34.1%, respectively. The dissolubility of all metals examined was positively correlated to the temperatures. The particle size would not change dissolution tendency of those heavy metals, but decrease the concentrations of leached heavy metals.展开更多
The objective of this study was to prepare and characterize paclitaxel-polyvinylpyrrolidone （PTX-PVP） solid dispersions with the intention of improving its solubility and dissolution properties. The PTX-PVP solid di...The objective of this study was to prepare and characterize paclitaxel-polyvinylpyrrolidone （PTX-PVP） solid dispersions with the intention of improving its solubility and dissolution properties. The PTX-PVP solid dispersion systems were prepared by solvent method. The release rate ofpaclitaxel was determined from dissolution studies and the physicochemical properties of solid dispersion were investigated by differential scanning calorimetry （DSC）, powder X-ray diffraction （PXRD） and scanning electron microscopy （SEM）. The cytotoxicities ofpaclitaxel in solid dispersion to the SKOV-3 cells were assayed by a SRB staining method. The results showed that the solubility and dissolution rate of paclitaxel were significantly improved in solid dispersion system compared with that of the pure drug and physical mixture. The results of DSC and PXRD showed that the paclitaxel in solid dispersion was amorphous form. No paclitaxel crystals in the solid dispersions was found during SEM analysis. Cytotoxicity study suggested that the inhibitory rates of PTX-PVP solid dispersion to SKOV-3 cells were higher than that of pure paclitaxel. The solubility and dissolution of paclitaxel were improved by solid dispersion technique. In vitro cytotoxicity of paclitaxel in solid dispersion was higher than that of pure drug.展开更多
Aim The objective of this study was to prepare and characterize quercetin-polyvinylpyrrolidone （Qurc-PVP） solid dispersion with the intention of improving its dissolution properties, Methods Qurc-PVP sclid dispersio...Aim The objective of this study was to prepare and characterize quercetin-polyvinylpyrrolidone （Qurc-PVP） solid dispersion with the intention of improving its dissolution properties, Methods Qurc-PVP sclid dispersion was prepared by solvent method. The release rate of quercetin was determined from dissolution studies and the physicochemical properties of solid dispersion were investigated by differential scanning calorimetry （DSC）, infrared spectroscopy （IR）, powder X-ray diffraction （PXRD） and scanning electron microscopy （SEM）. Results The results showed that the dissolution rate of quercetin was significantly improved by solid dispersion compared to that of the pure drug and physical mixture, Solubility studies revealed a markedly increase in the solubility of quercetin. The results of DSC and PXRD showed that the quercetin in solid dispersion was amorphous form. From SEM analysis, there was no quercetin crystal observed in the solid dispersions. Conclusion The solubility and dissolution of quercetin were improved by solid dispersion technique.展开更多
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 5x^3＋0.024 0x^2-0.287 3x＋ 1.276 7 for Na3AIF6-AIF3-Al2O3-CaF2-LiF- MgF2 system at 920 ℃.
文摘Aim To study the effect of complexation with hydroxylpropyl-β-cyclodextrin(HP-β-CD) on the solubility, dissolution rate and chemical stability of prostaglandin E_1 (PGE_1) ,thereby providing a basis for preparing a stable solid or aqueous preparation of PGE_1 formulatedwith HP-β-CD. Methods The effect of HP-β-CD on the solubility of PGE_1 was studied by phasesolubility method. The formation of inclusion complexes of PGE_1 with HP-β-CD in the aqueoussolution was confirmed by UV spectra, circular dichroism spectroscopy, and that in the solid stateby IR spectra and X-ray diffractome-try. An solid inclusion complex of PGE_1 with HP-β-CD wasprepared by lyophilization. The dissolution rate and stability of the inclusion complex weredetermined and compared with those of PGE_1 alone. Meanwhile, the stability of PGE_1 aqueoussolutions in the presence of HP-β-CD was studied under different pH conditions. Results Thesolubility of PGE_1 increased linearly with increasing HP-β-CD concentration in various pH bufferedsolutions, showing typical A_L-type phase solubility diagrams. The stability and dissolution rateof the solid inclusion complex of PGE_1 were significantly increased, compared with those of purePGE_1 . The stability of PGE_1 in HP-β-CD solutions was also obviously improved under acidic andbasic conditions, but the stabilizing effect was absent under neutral conditions. Conclusions Thesolubility,dissolution rate and chemical stability of PGE_1 are markedly improved by complexationwith HP-β-CD: It is quite possible to prepare a stable PGE_1 inclusion complex-containing soliddosage forms, but almost impossible to obtain a stable aqueous preparation of PGE_1 formulated withHP-β-CD.
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 effects of re-crystallization of prednisolone as a poorly water-soluble drug in aqueous surfactant solutions on its dissolution rate were investigated. A significant enhancement was observed for crystal dissolution rate in hydrophilic surfactants such as tween 80 and sodium lauryl sulfate （SLS）. Differential scanning calorimetry （DSC） and Fourier transform infrared spectroscopy （FT-IR） indicated the existence of both form Ⅰ and Ⅱ ofprednisolone in SLS treated crystals. The FT-IR results also showed that, only form Ⅱ could be detected in prednisolone crystals without surfactant and prednisolone form Ⅲ was produced in tween 80 treated crystals. These results were also confirmed by X-ray （XRD） diffraction and scanning electron microscopy （SEM）. In general, the results indicated that the presence of hydrophilic surfactants could generate forms Ⅱ and Ⅲ of the crystals. These forms would give rlse to the increase of prednisolone＇s dissolution rate owing to their physicochemical instability and more hydrophilic property in comparison with stable polymorph of form Ⅰ.
基金supported by the National Natural Science Foundation of China(Grant Nos.42222208,42488101)。
文摘Feldspar minerals are widely present in clastic reservoirs of hydrocarbon-bearing basins,where they undergo significant dissolution during burial processes.The dissolution kinetics and evolutionary trends of feldspar under burial conditions are critical for the formation of secondary porosity and the evolution of reservoir spaces.The feldspar dissolution process is frequently associated with the precipitation and transformation of complex authigenic minerals,making it challenging to accurately determine dissolution rates under near-equilibrium conditions.This study performed experimental simulations of feldspar(K-feldspar and albite)dissolution under conditions ranging from far-from-equilibrium to near-equilibrium,with varying temperatures and pCO_(2).Under near-equilibrium conditions,scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),and laser confocal microscopy were employed to achieve accurate quantification of the dissolution volume of feldspar samples.The dissolution rates of feldspar under near-equilibrium conditions,along with the factors influencing these rates,were systematically investigated.The results indicate that the dissolution rates of K-feldspar under near-equilibrium conditions at temperatures and pCO_(2)levels of 80℃/1 bar,120℃/4.2 bar,and 160℃/17.9 bar are 2.16695×10^(15)–8.040×10^(15),4.49288×10^(15)–1.480×10^(14),and 6.17462×10^(15)–2.496×10^(14)mol cm^(-2)s^(-1),respectively.Under the same near-equilibrium conditions,the dissolution rates of albite are 2.93294×10^(15)–1.365×10^(14),5.54499×10^(15)–2.170×10^(14),and 9.42841×10^(15)–3.074×10^(14)mol cm^(-2)s^(-1),respectively.The dissolution rates of feldspar under near-equilibrium conditions are significantly lower(1.5–2orders of magnitude at high temperatures)than those under far-equilibrium conditions.Furthermore,as the temperature increases by a gradient of 40℃,the dissolution rate only increases by only 1.5 times,which is substantially lower than the rate increase observed under far-equilibrium conditions.The discrepancy between feldspar dissolution rates under far-equilibrium conditions(L-TST)and near-equilibrium conditions increases with rising temperature.Under identical experimental conditions,the dissolution rate of albite under near-equilibrium conditions is higher than that of K-feldspar.The precipitation and transformation of secondary minerals regulate feldspar dissolution under near-equilibrium conditions by altering ion concentrations in the solution.The p H of the solution also plays a significant role in controlling feldspar dissolution under near-equilibrium conditions.This study establishes a method for quantitatively analyzing mineral dissolution using the surface morphological features of dissolved and undissolved segments of polished feldspar samples.This method avoids relying on changes in ion concentrations in the reaction solution,making it more reasonable and widely applicable.Moreover,the results provide valuable insights into feldspar dissolution kinetics under burial conditions within closed systems,enabling a more accurate assessment of the contribution of feldspar dissolution to pore formation in reservoirs.
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.
文摘Chemically resistant anodic oxide layers were formed on pure aluminum substrates in oxalic acid-sulphuric acid bath.Acid dissolution tests of the obtained anodic layers were achieved in accordance with the ASTM B 680-80 specifications：35mL/L 85% H3PO4＋20g/L CrO3 at 38℃.Influence of oxalic acid concentration,bath temperature and anodic current density on dissolution rate and coating ratio was examined,when the sulphuric acid concentration was maintained at 160g/L.It was found that chemically resistant and compact oxide layers were produced under low operational temperature （5℃） and high current densities （3A/dm^2）.A beneficial effect was observed concerning the addition of oxalic acid （18g/L）.The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy （SEM）,atomic force microscopy （AFM） and glow-discharge optical emission spectroscopy （GDOES）.
基金supported by the National Science and Technology Major Project ‘‘Bohai Bay Basin deep oil and gas geology and reserves increasing direction’’ (No. 2016ZX05006007)the National Natural Fund (Youth) ‘‘Relationship between rich feldspar sandstone reservoirs in feldspar alteration and pyrolysis of hydrocarbons’’ (41602138)
文摘In order to clarify the dynamic process of feldspar dissolution-precipitation and explore the formation mechanism of secondary porosity,six batch reactor experiments were conducted at 200℃and pH=7 measured at room temperature.Temporal evolution of fluid chemistry was analyzed with an inductively coupled plasma optical emission spectrometer(ICP-OES).Solid reaction products were retrieved from six batch experiments terminated after 36,180,276,415,766 and 1008 h.Scanning electron microscopy(SEM)revealed dissolution features and significant secondary mineral adhered on the feldspar surface.The process of feldspar dissolution-precipitation proceeded slowly and full equilibrium was not achieved after 1008 h.Saturation indices suggested that the albite and K-feldspar dissolution occurred throughout the experiments.The average dissolution rates for albite and K-feldspar were 2.28×10^-10 and 8.51×10^-11 mol m^-2 s^-1,respectively.Based on the experimental data,the reaction process of alkaline feldspar was simulated and the secondary porosity had increased 0.3%after the experiment.
基金financially supported by the National Key Research and Development Program of China(No.2019YFC1908403)the National Research Foundation from the government of the Republic of Korea(Nos.2022K1A3A1A20014496 and 2022R1F1A1074707)。
文摘The dissolution performance of black aluminum dross(BAD)in cryolite electrolyte is key to its recovery by molten salt electrolysis.The stable operation of the electrolyzer depends mainly on the rapid dissolution of BAD in Na_(3)AlF_(6)-AlF_(3)-Al_(2)O_(3)electrolyte system.In this paper,the dissolution performance and behavior of BAD and its main components in the cryolite system were studied,and the saturation solubility of aluminum nitride in this system was determined.The dissolution performance of BAD in cryolite electrolyte before and after denitration was compared,and the effects of temperature,cryolite ratio,and the doping ratio of BAD and alumina on the dissolution rate were investigated.The obtained results showed that aluminum nitride was the main factor affecting the dissolution performance of BAD in the electrolyte.Aluminum nitride was partly converted toα-Al_(2)O_(3)after addition to the electrolyte,and the convertedα-Al_(2)O_(3)was partially dissolved in the cryolite electrolyte,while the remaining precipitated and accumulated at the bottom with aluminum nitride.Aluminum nitride was almost insoluble in the cryolite electrolyte,with 0.0022%solubility.A higher proportion ofα-Al_(2)O_(3)in BAD was negatively influenced its solubility in the cryolite electrolyte.The dissolution rate of BAD in cryolite electrolytes was effectively improved by mixing BAD withγ-Al_(2)O_(3).
基金Funded by the National Natural Science Foundation of China(No.51701100)the China Postdoctoral Science Foundation(No.2020T130552)the Science and Technology Support Plan for Youth Innovation of Colleges in Shandong Province。
文摘The dissolution behavior of delta ferrites in martensitic heat-resistant steel was studied.And the reason why the dissolution rate of delta ferrites decreased with dissolution time was discussed.The experimental results show that the chemical compositions of delta ferrites negligibly change with dissolution time.The decrease of dissolution rate of delta ferrites with dissolution time should be attributed to the change of shape and distribution of delta ferrites.The shape of delta ferrites tends to transfer from polygon to sphere with dissolution time,causing the decrease of specific surface area of delta ferrites.The distribution position of delta ferrites tends to transfer from boundaries of austenite grains to interior of austenite grains with dissolution time,decreasing the diffusion coefficient of alloy atoms.Both them decrease the dissolution rate of delta ferrites.
基金the Institute of Particle and Science Engineering,University of Leeds and Procter & Gamble Newcastle Innovation Centre(UK) for partially funding the project
文摘Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.
基金the Institute of Particle and Science Engineering,University of Leeds and Procter&Gamble Newcastle Innovation Centre(UK)for partially funding the project
文摘Dissolution kinetics of sodium carbonate is investigated with the image analysis method at the approach of single particle.The dissolution experiments are carried out in an aqueous solution under a series of controlled temperature and p H.The selected sodium carbonate particles are all spherical with the same mass and diameter.The dissolution process is quantified with the measurement of particle diameter from dissolution images.The concentration of dissolved sodium carbonate in solvent is calculated with the measured diameter of particle.Both surface reaction model and mass transport model are implemented to determine the dissolution mechanism and quantify the dissolution rate constant at each experimental condition.According to the fitting results with both two models,it is clarified that the dissolution process at the increasing temperature is controlled by the mass transport of dissolved sodium carbonate travelling from particle surface into solvent.The dissolution process at the increasing pH is controlled by the chemical reaction on particle surface.Furthermore,the dissolution rate constant for each single spherical sodium carbonate particle is quantified and the results show that the dissolution rate constant of single spherical sodium carbonate increases significantly with the rising of temperature,but decreases with the increasing of pH conversely.
基金financial support of FEES-CONARE(Ref 115B5662)the University of Costa Rica(UCR)+1 种基金the Costa Rica Institute of Technology(TEC)the National Laboratory of Nanotechnology(LANOTEC)
文摘Irbesartan(IBS)is a tetrazole derivative and antihypertensive drug that has two interconvertible structures,1H-and 2H-tautomers.The difference between them lies in the protonation of the tetrazole ring.In the solid-state,both tautomers can be isolated as crystal forms A(1H-tautomer)and B(2H-tautomer).Studies have reported that IBS is a polymorphic system and its forms A and B are related monotropically.These reports indicate form B as the most stable and less soluble form.Therefore,the goal of this contribution is to demonstrate through a complete solid-state characterization,thermodynamic study and dissolution properties that the IBS forms are desmotropes that are not related monotropically.However,the intention is also to call attention to the importance of conducting strict chemical and in solid-state quality controls on the IBS raw materials.Hence,powder X-ray diffraction(PXRD)and Raman spectroscopy(RS)at ambient and non-ambient conditions,differential scanning calorimetry(DSC),hot stage microscopy(HSM),Fourier transform infrared(FT-IR)and scanning electron microscopy(SEM)techniques were applied.Furthermore,intrinsic dissolution rate(IDR)and structural stability studies at 98%relative humidity(RH),25℃and 40℃were conducted as well.The results show that in fact,form A is approximately four-fold more soluble than form B.In addition,both IBS forms are stable at ambient conditions.Nevertheless,structural and/or chemical instability was observed in form B at 40℃and 98%RH.IBS has been confirmed as a desmotropic system rather than a polymorphic one.Consequently,forms A and B are not related monotropically.
基金funded by Department of Materials Science and Engineering of Norwegian University of Science and Technology(NTNU)in cooperation with the SFI Metal production(NRC 237738).
文摘Carbon dissolution from four types of metallurgical cokes and graphite was investigated by using immersion rods in a resistance furnace to clarify the influence of factors governing the rate of carbon dissolution from carbonaceous materials into Fe-Mn melts at 1550℃.The factors studied were the nmicrostructure of carbonaceous materials,roughness,porosity and the wettability between carbonaceous materials and the melt.Carbon/metal in terface was characterised by sea nning electron microscopy accompanied with energy-dispersive X-ray spectrometry to investigate the form at io n of an ash layer.The results showed that coke E had the highest dissolution rate.Surface roughness and porosity of the carbonaceous materials seemed to be dominant factors affecting the dissolution rates.Further,crystallite size did not have a significant effect on the dissolution rates.Solid/liquid wettability seemed to affect the initial stage of dissolution reaction.The dissolution mechanism was found to be both mass transfer and interfacial reactions.
文摘Inclusion complexation between ibuprofen (IBF) and βcyclodextrin (βCD) was investigated. Phase solubility studies of the complexation suggested the formation of a 1:3 complex and a 2:3 complex between IBF and βCD at room temperature (23℃) and at 37℃ respectively. Solid inclusion complexes were prepared by the homogeneous coprecipitation method. Scanning electron microscopy, differential scanning calorimetry, IR spectroscopy, and Xray diffractometry were used for the characterization and evaluation of the complexes. The solubility and dissolution rate of the complexes formed were found to have improved considerably over that of the physical mixture and the drug alone, indicating that βcyclodextrin played an important role in the solubilization of ibuprofen.
基金support of the Open Fund from the State Key Laboratory of New-tech for Chinese Medicine Pharmaceutical Process(SKL2020Z0203)Science and Technology Project of Haihe Laboratory of Modern Chinese Medicine(22HHZYSS00004)the 14th University Student Science and Technology Innovation Fund of Tianjin University of Traditional Chinese Medicine(KJ12)。
文摘To validate the feasibility of using near-infrared(NIR)spectroscopy for real-time monitoring of multiple active pharmaceutical ingredients dissolution,this study focused on Guizhi Fuling capsules and tablets.The NIR spectroscopy fiber probe was inserted into the dissolution apparatus and connected to a Fourier transform near-infrared spectrometer(FT-NIR)to capture spectral data.During the dissolution tests,dissolution behavior curves for seven components,gallic acid(GA),alibiflorin(ALI),paeoniflorin(PF),paeonol(PAE),amygdalin(AMY),cinnamaldehyde(CL),and cinnamic acid(CA)in the capsules,were obtained by sampling from the dissolution cups at specific time intervals.Linear regression was applied to models corrected using various pre-process techniques with the partial least squares(PLS)algorithm.Additionally,an artificial neural network(ANN),a nonlinear regression algorithm,was utilized to explore the complex relationship between spectra and multicomponent dissolution.Ultimately,the ANN model achieved a lower prediction mean square error(RMSEP)and relative error compared to the PLS model,with significantly higher correlation coefficient(Rp)for the validation set.The highest Rpvalue reached 0.8825.The paired t-test results also indicated no significant difference between predicted and measured values.Furthermore,the ANN model demonstrated the best predictive performance in the tablet experiments,achieving an Rpof 0.8134.The findings indicate that real-time monitoring of multicomponent drug dissolution using NIR spectroscopy combined with chemometric methods is feasible,offering a promising new direction to replace traditional dissolution testing.
基金Projects(41073060,21007009)supported by the National Natural Science Foundation of China"Chen Guang" project(10CG34)supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation,ChinaProjects(20100075120010,20100075110010)supported by Research Fund for the Doctoral Program of Higher Education of China
文摘AThe wastewater source of 4# tailing pond in Dexing copper mine consists of alkaline flotation pulp and acid mine drainage （AMD） from the nearby opencast mine. Therefore, the heavy metals in tailing ore are very likely to be released due to acidification from AMD. The leaching behaviors ofZn, Cu, Fe and Mn in mine tailings from Dexing copper mine were investigated by a series of laboratory batch experiments. The effectcs ofpH, temperature, particle size and contact time on the leachability of such heavy metals were examined. It was evident that Zn, Cu, Fe and Mn were major heavy metals in the tailings while gangue minerals like quartz were major constituents in examined tailings. The tailing dissolution reaction was controlled by the acid, whose kinetics could be expressed according to the heterogeneous reaction models and explained by a shrinking core model with the surface chemical reaction as the rate-controlling step. The leachability of all metals examined depended on pH and contact time. The batch studies indicated that the maximum leaching ratios ofZn, Cu, Fe and Mn at pH 2.0 were 5.4%, 5.8%, l 1.1% and 34.1%, respectively. The dissolubility of all metals examined was positively correlated to the temperatures. The particle size would not change dissolution tendency of those heavy metals, but decrease the concentrations of leached heavy metals.
文摘The objective of this study was to prepare and characterize paclitaxel-polyvinylpyrrolidone （PTX-PVP） solid dispersions with the intention of improving its solubility and dissolution properties. The PTX-PVP solid dispersion systems were prepared by solvent method. The release rate ofpaclitaxel was determined from dissolution studies and the physicochemical properties of solid dispersion were investigated by differential scanning calorimetry （DSC）, powder X-ray diffraction （PXRD） and scanning electron microscopy （SEM）. The cytotoxicities ofpaclitaxel in solid dispersion to the SKOV-3 cells were assayed by a SRB staining method. The results showed that the solubility and dissolution rate of paclitaxel were significantly improved in solid dispersion system compared with that of the pure drug and physical mixture. The results of DSC and PXRD showed that the paclitaxel in solid dispersion was amorphous form. No paclitaxel crystals in the solid dispersions was found during SEM analysis. Cytotoxicity study suggested that the inhibitory rates of PTX-PVP solid dispersion to SKOV-3 cells were higher than that of pure paclitaxel. The solubility and dissolution of paclitaxel were improved by solid dispersion technique. In vitro cytotoxicity of paclitaxel in solid dispersion was higher than that of pure drug.
文摘Aim The objective of this study was to prepare and characterize quercetin-polyvinylpyrrolidone （Qurc-PVP） solid dispersion with the intention of improving its dissolution properties, Methods Qurc-PVP sclid dispersion was prepared by solvent method. The release rate of quercetin was determined from dissolution studies and the physicochemical properties of solid dispersion were investigated by differential scanning calorimetry （DSC）, infrared spectroscopy （IR）, powder X-ray diffraction （PXRD） and scanning electron microscopy （SEM）. Results The results showed that the dissolution rate of quercetin was significantly improved by solid dispersion compared to that of the pure drug and physical mixture, Solubility studies revealed a markedly increase in the solubility of quercetin. The results of DSC and PXRD showed that the quercetin in solid dispersion was amorphous form. From SEM analysis, there was no quercetin crystal observed in the solid dispersions. Conclusion The solubility and dissolution of quercetin were improved by solid dispersion technique.
