The reactive crystallization process of dexamethasone sodium phosphate was investigated in a continuous mixed-suspension, mixed-product-removal(MSMPR) crystallizer. Analyzing experimental data, it was found that the g...The reactive crystallization process of dexamethasone sodium phosphate was investigated in a continuous mixed-suspension, mixed-product-removal(MSMPR) crystallizer. Analyzing experimental data, it was found that the growth of product crystal was size-dependent. The Bransom, CR, ASL, M J2 and M J3 size-dependent growth models were discussed in details. Using experimental steady state population density data of dexamethasone sodium phosphate, parameters of five size-dependent growth models were determined by the method of non-linear least-squares. By comparison of experimental population density and linear growth rate data with those obtained from the five size-dependent growth models, it was found that the MJ3 model predicts the growth more accurately than do the other four models. Based on the theory of population balance, the crystal nucleation and growth rate equations of dexamethasone sodium phosphate were determined by non-linear regression method. The effects of different operation parameters such as supersaturation, magma density and temperature on the quality of product crystal were also discussed, and the optimal operation conditions were derived.展开更多
Crystal morphology is known to be of great importance to the end-use properties of crystal products, and to affect down-stream processing such as filtration and drying. However, it has been previously regarded as too ...Crystal morphology is known to be of great importance to the end-use properties of crystal products, and to affect down-stream processing such as filtration and drying. However, it has been previously regarded as too challenging to achieve automatic closed-loop control. Previous work has focused on controlling the crystal size distribution, where the size of a crystal is often defined as the diameter of a sphere that has the same volume as the crystal. This paper reviews the new advances in morphological population balance models for modelling and simulating the crystal shape distribution （CShD）, measuring and estimating crystal facet growth kinetics, and two- and three-dimensional imaging for on-line characterisation of the crystal morphology and CShD. A framework is presented that integrates the various components to achieve the ultimate objective of model-based closed-loop control of the CShD. The knowledge gaps and challenges that require further research are also identified.展开更多
We calculate structural, electronic properties and chemical bonding of borate Li4CaB2O6 under high pressure by means of the local density-functional pseudopotential approach. The equilibrium lattice constants, density...We calculate structural, electronic properties and chemical bonding of borate Li4CaB2O6 under high pressure by means of the local density-functional pseudopotential approach. The equilibrium lattice constants, density of states, Mulliken population, bond lengths, bond angles as well as the pressure dependence of the band gap are presented. Analysis of the simulated high pressure band structure suggests that borate Li4CaB2O6 can be used as the semi-conductor optical material. Based on the Mulliken population analysis, it is found that the electron transfer of the Li atom is very different from that of other atoms in the studied range of high pressures. The charge populations of the Li atom decrease with the pressure up to 60 GPa, then increase with the pressure.展开更多
To study the extraction difficulty of lithium ions from various crystal planes of Li2 TiO3, according to the first principle, four representative crystal surfaces of Li2TiO3（precursor）,（-133）,（-206）,（002） and...To study the extraction difficulty of lithium ions from various crystal planes of Li2 TiO3, according to the first principle, four representative crystal surfaces of Li2TiO3（precursor）,（-133）,（-206）,（002） and（-131）, were selected to establish a model and to calculate the surface energy, bond length and population using Materials Studio 5.5（MS 5.5）. The results demonstrate that there is no direct relationship between the surface energy and the order of disappearance of the four diffraction peaks when lithium titanate is treated with hydrochloric acid, instead, the difficulty of Li~＋ extraction from various crystal faces corresponds to the Li-O bond strength. Lithium ion is easy to remove from（-133） and（-206） due to the relatively weak Li-O bond strength. In contrast, Li＋ extraction requires a longer time for（002） and（-131）.展开更多
文摘The reactive crystallization process of dexamethasone sodium phosphate was investigated in a continuous mixed-suspension, mixed-product-removal(MSMPR) crystallizer. Analyzing experimental data, it was found that the growth of product crystal was size-dependent. The Bransom, CR, ASL, M J2 and M J3 size-dependent growth models were discussed in details. Using experimental steady state population density data of dexamethasone sodium phosphate, parameters of five size-dependent growth models were determined by the method of non-linear least-squares. By comparison of experimental population density and linear growth rate data with those obtained from the five size-dependent growth models, it was found that the MJ3 model predicts the growth more accurately than do the other four models. Based on the theory of population balance, the crystal nucleation and growth rate equations of dexamethasone sodium phosphate were determined by non-linear regression method. The effects of different operation parameters such as supersaturation, magma density and temperature on the quality of product crystal were also discussed, and the optimal operation conditions were derived.
基金Financial support from the following projects and organisa- tions are acknowledged： the China One Thousand Talent Scheme, the National Natural Science Foundation of China （NNSFC） under its Major Research Scheme of Meso-scale Mechanism and Control in Multi-phase Reaction Processes （project reference： 91434126）, the Natural Science Foundation of Guangdong Province （project reference： 2014A030313228）, the UK Engineering and Physical Sciences Research Council （EPSRC） for the projects of Shape （EP/C009541） and StereoVision （EP/E045707）, and the Technology Strategy Board （TSB） for the project of High Value Manufacturing CGM （TP/BD059E）.
文摘Crystal morphology is known to be of great importance to the end-use properties of crystal products, and to affect down-stream processing such as filtration and drying. However, it has been previously regarded as too challenging to achieve automatic closed-loop control. Previous work has focused on controlling the crystal size distribution, where the size of a crystal is often defined as the diameter of a sphere that has the same volume as the crystal. This paper reviews the new advances in morphological population balance models for modelling and simulating the crystal shape distribution （CShD）, measuring and estimating crystal facet growth kinetics, and two- and three-dimensional imaging for on-line characterisation of the crystal morphology and CShD. A framework is presented that integrates the various components to achieve the ultimate objective of model-based closed-loop control of the CShD. The knowledge gaps and challenges that require further research are also identified.
基金Supported by the National Natural Science Foundation of China under Grant No 10676025.
文摘We calculate structural, electronic properties and chemical bonding of borate Li4CaB2O6 under high pressure by means of the local density-functional pseudopotential approach. The equilibrium lattice constants, density of states, Mulliken population, bond lengths, bond angles as well as the pressure dependence of the band gap are presented. Analysis of the simulated high pressure band structure suggests that borate Li4CaB2O6 can be used as the semi-conductor optical material. Based on the Mulliken population analysis, it is found that the electron transfer of the Li atom is very different from that of other atoms in the studied range of high pressures. The charge populations of the Li atom decrease with the pressure up to 60 GPa, then increase with the pressure.
基金Funded partly by the Key Project of Natural Science of Sichuan Provincial Education Department(No.16ZA0309)the Doctoral Research Start-up Funding(No.15B16)
文摘To study the extraction difficulty of lithium ions from various crystal planes of Li2 TiO3, according to the first principle, four representative crystal surfaces of Li2TiO3（precursor）,（-133）,（-206）,（002） and（-131）, were selected to establish a model and to calculate the surface energy, bond length and population using Materials Studio 5.5（MS 5.5）. The results demonstrate that there is no direct relationship between the surface energy and the order of disappearance of the four diffraction peaks when lithium titanate is treated with hydrochloric acid, instead, the difficulty of Li~＋ extraction from various crystal faces corresponds to the Li-O bond strength. Lithium ion is easy to remove from（-133） and（-206） due to the relatively weak Li-O bond strength. In contrast, Li＋ extraction requires a longer time for（002） and（-131）.
