With the high-quality requirements for cephalexin monohydrate,developing a robust and practical crystallization process to produce cephalexin monohydrate with good crystal habit,appropriate aspect ratio and high bulk ...With the high-quality requirements for cephalexin monohydrate,developing a robust and practical crystallization process to produce cephalexin monohydrate with good crystal habit,appropriate aspect ratio and high bulk density as well as suitable flowability is urgently needed.This research has explored the influence of ultrasound on crystallization of cephalexin monohydrate in terms of nucleation mechanism and crystal habit control.The results of metastable zone width and induction time measurement showed the presence of ultrasound irradiation can narrow the metastable zone and shorten induction time.Cavitation phenomena generated by ultrasound were used to qualitatively explain the mechanism of ultrasound promoting nucleation of cephalexin monohydrate.Furthermore,on the basis of classical nucleation theory and induction time data,a series of nucleation-related parameters(such as crystalliquid interfacial tension,radius of the critical nucleus and etc.)were calculated and showed a decreasing trend under ultrasound irradiation.The diffusion coefficient of the studied system was also determined to increase by 72.73%under ultrasound.The changes in these parameters have quantitatively confirmed the mechanism of ultrasound influence on the nucleation process.In further,the calculated surface entropy factor has confirmed that the growth of cephalexin monohydrate follows continuous growth mechanism under the research conditions of this work.Through the exploration of crystallization conditions,it is found that suitable ultrasonic treatment,seeding,supersaturation control and removal of fine crystals are conducive to improving the quality of cephalexin monohydrate product.Optimizing the crystallization process coupled continuous ultrasound irradiation with fine-crystal dissolution policy has achieved the controllable production of monodisperse cephalexin monohydrate crystal with good performance.展开更多
BaY2F8 crystals had a relatively low symmetry, and its XRD data showed that those strong diffractions occured in a narrow angle range, so it was difficult to orientate the single crystals of BaYEFs. In this paper, bas...BaY2F8 crystals had a relatively low symmetry, and its XRD data showed that those strong diffractions occured in a narrow angle range, so it was difficult to orientate the single crystals of BaYEFs. In this paper, based on the structure characteristics and XRD data, the crystal habit of BaY2F8 was analyzed. The strong bond in crystal structure of BaYEF8 was Y-FE-Y, which stretched to the shape of chain along the direction of [001]. And this was an advantaged direction for the crystal growth. The steady shapes of BaY2F8 were composed of rhombic prism { 130} and {021 }. The crystal showed an axial habit in the direction of [001]. The analysis of the crystal slice obtained by temperature gradient technique verified the above conclusion. The BaY2F8 crystal was grown by compulsive methods such as Czochralski method.展开更多
The effects of solvent and impurity on the crystal habit of 11α-hydroxy-16α,17α-epoxyprogesterone (HEP)grown from solution were studied by scanning electron microscope.Long prismatic crystals were produced when HEP...The effects of solvent and impurity on the crystal habit of 11α-hydroxy-16α,17α-epoxyprogesterone (HEP)grown from solution were studied by scanning electron microscope.Long prismatic crystals were produced when HEP was crystallized from pure acetone and N,N-dimethylformamide,while blocky crystals were produced from pure chloroform by cooling crystallization.One kind of isomorphic impurity,16α,17α-epoxyprogesterone(EP) was selected to examine its effect on the HEP crystal habit.When the content of EP in the mother liquor is very high(55.45%,solvent free basis),the habit of produced HEP crystals was greatly modified from prismatic to octa-hedral.The differential scanning calorimetry and X-ray powder diffraction analyses showed that the change of crystal habit was originated from the crystal structure modification.展开更多
The preparation of X-zeolite powder was investigated in hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microsc...The preparation of X-zeolite powder was investigated in hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microscope and infrared ray. The results show that X-zeolite powder with uniform granularity and intact crystal shape can be obtained in hydrothermal system of acid-treated stellerite KG-*5CD*2KG-*9NaOHKG-*5CD*2KG-*9NaAl(OH)4KG-*5CD*2KG-*9H2O; the crystallite size is in the range of 2CD*23μm. The best reaction time of hydrothermal preparation is 6h. The formation phases of X-zeolite crystal are as follows: dissolution of feedstocks → formation of [SiO4] 4- and [AlO4] 5- tetrahedron, many-membered ring, β cage → formation of crystal nucleus and nano-particle → aggregation growth of nano-particle → coalescence growth of crystallite. The crystal habits of X-zeolite are intimately related with crystallization orientation of β cage in crystal and with its coupling stability on every crystal face family.展开更多
Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately co...Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately control the solid form and crystal habit of triphenylmethanol(Ph_(3)COH). This advanced technique separates the primary mixing of solutions from crystal formation(nucleation and growth) by introducing the microfluidic device, avoiding clogging in microchannels to obtain high-quality crystals. The results show that we can achieve controllable preparation of pure 2Ph_(3)COH·DMSO(DMSO solvate), pure Ph_(3)COH(form β), and mixed crystals with different mass ratios. Moreover, the microscale can prompt the DMSO solvate to grow into hexagonal sheet-like and bulk crystals. We can regulate the aspect ratio of hexagonal sheet-like crystals in binary solvents and control the crystal habit of the form β to transition between long needle-like shapes and short hexagonal prisms in DMF-H_(2)O. Meanwhile, we revealed that the solvent ratio, the antisolvent flow rate, and the initial concentration of Ph_(3)COH are the main factors affecting the solid form selectivity and morphology transition. Such a novel method would be considered as a promising technique to be extended to screen and control key crystallization parameters of other substances.展开更多
By means of constant control speed cooling crystallization,the influences of four additives,including lead chloride,cadmium chloride,sodium salicylate,and quaternary ammonium salt,on the crystal habit of KCl were inve...By means of constant control speed cooling crystallization,the influences of four additives,including lead chloride,cadmium chloride,sodium salicylate,and quaternary ammonium salt,on the crystal habit of KCl were investigated.The results show that the crystal habit of KCl is cube without additives,the crystal habit of KCl is ellipsoid-like in the presence of Pb^(2+),the crystal habit of KCl is strip in the presence of Cd^(2+),and the crystal habit of KCl is cavate cube in the presence of sodium salicylate.Xray diffractometry analysis reveals that these additives can change the crystal habit of KCl but not its crystal structure.展开更多
6-aminopenicillanic acid (6-APA) crystals obtained under different physical and chemical conditions of the solutions may present different habits. The habits of diamond-shaped plates are desirable compared with other ...6-aminopenicillanic acid (6-APA) crystals obtained under different physical and chemical conditions of the solutions may present different habits. The habits of diamond-shaped plates are desirable compared with other habits of 6-APA crystals. To obtain ideal 6-APA crystals, the effects of the mixed solvents and additives on 6-APA crystal habits were investigated. Ethanol or acetone was used as the organic solvent, and impurities existing in the 6-APA purification process were used as the additives. 6-APA growth habits were changed when the concentrations of ethanol, acetone or phenyl acetic acid were increased to exceed their critical concentration. The observed results show that the dominant face on 6-APA crystals was identified to be {020}, but the overall habit was controlled by the relative growth rates of the {101} and {002} faces. Crystal growth rates and habits can be appreciably changed by specific adsorption of additives on crystal faces.In some cases solvent molecules can act in a similar way and may be regarded as bulk additives. The effects of additives and organic solvents on 6-APA crystal habits were the results of adsorption effect, which fitted the experimental results quite well.展开更多
A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symme...A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a self-consistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects(such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.展开更多
Batch crystallization in acidic aqueous solution of cephalexin was conducted by reactive crystallization with or without seeding. Supersaturation was generated by mixing ammonia and acidic aqueous solution of cephalex...Batch crystallization in acidic aqueous solution of cephalexin was conducted by reactive crystallization with or without seeding. Supersaturation was generated by mixing ammonia and acidic aqueous solution of cephalexin and controlled by solution feeding rate and seeding conditions. UV and Morphologi G3 were used to measure supersaturation and aspect ratio. Experimental results demonstrated that burst nucleation occurred and the products were needle-like at high supersaturation;meanwhile, the products were plate-like and had high aspect ratio at low supersaturation. Analysis of the measured supersaturation profi les and corresponding aspect ratio explained the mechanisms governing the aspect ratio. The optimized operating parameters were also proposed (seeding supersaturation is equal to 1.3, seed mass ratio 8% and feeding rate 368 μL/min).展开更多
The growth habit of the basic magnesium oxysulfate whisker was investigated based on the theoreticalmodelof anion coordination polyhedron growth units.It is found that typicalbasic magnesium oxysulfate whisker growth ...The growth habit of the basic magnesium oxysulfate whisker was investigated based on the theoreticalmodelof anion coordination polyhedron growth units.It is found that typicalbasic magnesium oxysulfate whisker growth is consistent with anion tetrahedralcoordination incorporation rules.The growth units of basic magnesium oxysulfate whiskers are [Mg-(OH)_4]^(2-) and HSO_4^-.[Mg-(OH)_4]^(2-) is the favorable growth unit and whisker growth is in the direction of the [Mg-(OH)_4]^(2-) combination.A plurality of [Mg-(OH)_4]^(2-) s combine and become a larger dimensionalgrowth unit in a one-dimensionaldirection.Then HSO_4^- and larger dimensionalgrowth units connect as basic magnesium sulfate whiskers,according to the structuralcharacteristics of the basic magnesium sulfate whisker,which can guide the synthesis of magnesium hydroxide whisker.展开更多
基金the financial support of National Natural Science Foundation of China(22078238)Special Project for the Transformation of Major Scientific and Technology Achievements of Hebei Province(19042822Z).
文摘With the high-quality requirements for cephalexin monohydrate,developing a robust and practical crystallization process to produce cephalexin monohydrate with good crystal habit,appropriate aspect ratio and high bulk density as well as suitable flowability is urgently needed.This research has explored the influence of ultrasound on crystallization of cephalexin monohydrate in terms of nucleation mechanism and crystal habit control.The results of metastable zone width and induction time measurement showed the presence of ultrasound irradiation can narrow the metastable zone and shorten induction time.Cavitation phenomena generated by ultrasound were used to qualitatively explain the mechanism of ultrasound promoting nucleation of cephalexin monohydrate.Furthermore,on the basis of classical nucleation theory and induction time data,a series of nucleation-related parameters(such as crystalliquid interfacial tension,radius of the critical nucleus and etc.)were calculated and showed a decreasing trend under ultrasound irradiation.The diffusion coefficient of the studied system was also determined to increase by 72.73%under ultrasound.The changes in these parameters have quantitatively confirmed the mechanism of ultrasound influence on the nucleation process.In further,the calculated surface entropy factor has confirmed that the growth of cephalexin monohydrate follows continuous growth mechanism under the research conditions of this work.Through the exploration of crystallization conditions,it is found that suitable ultrasonic treatment,seeding,supersaturation control and removal of fine crystals are conducive to improving the quality of cephalexin monohydrate product.Optimizing the crystallization process coupled continuous ultrasound irradiation with fine-crystal dissolution policy has achieved the controllable production of monodisperse cephalexin monohydrate crystal with good performance.
基金the Natural Science Foundation of Tianjin, China (07JCZDJC00600, 07JCYBJC06000)
文摘BaY2F8 crystals had a relatively low symmetry, and its XRD data showed that those strong diffractions occured in a narrow angle range, so it was difficult to orientate the single crystals of BaYEFs. In this paper, based on the structure characteristics and XRD data, the crystal habit of BaY2F8 was analyzed. The strong bond in crystal structure of BaYEF8 was Y-FE-Y, which stretched to the shape of chain along the direction of [001]. And this was an advantaged direction for the crystal growth. The steady shapes of BaY2F8 were composed of rhombic prism { 130} and {021 }. The crystal showed an axial habit in the direction of [001]. The analysis of the crystal slice obtained by temperature gradient technique verified the above conclusion. The BaY2F8 crystal was grown by compulsive methods such as Czochralski method.
文摘The effects of solvent and impurity on the crystal habit of 11α-hydroxy-16α,17α-epoxyprogesterone (HEP)grown from solution were studied by scanning electron microscope.Long prismatic crystals were produced when HEP was crystallized from pure acetone and N,N-dimethylformamide,while blocky crystals were produced from pure chloroform by cooling crystallization.One kind of isomorphic impurity,16α,17α-epoxyprogesterone(EP) was selected to examine its effect on the HEP crystal habit.When the content of EP in the mother liquor is very high(55.45%,solvent free basis),the habit of produced HEP crystals was greatly modified from prismatic to octa-hedral.The differential scanning calorimetry and X-ray powder diffraction analyses showed that the change of crystal habit was originated from the crystal structure modification.
文摘The preparation of X-zeolite powder was investigated in hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microscope and infrared ray. The results show that X-zeolite powder with uniform granularity and intact crystal shape can be obtained in hydrothermal system of acid-treated stellerite KG-*5CD*2KG-*9NaOHKG-*5CD*2KG-*9NaAl(OH)4KG-*5CD*2KG-*9H2O; the crystallite size is in the range of 2CD*23μm. The best reaction time of hydrothermal preparation is 6h. The formation phases of X-zeolite crystal are as follows: dissolution of feedstocks → formation of [SiO4] 4- and [AlO4] 5- tetrahedron, many-membered ring, β cage → formation of crystal nucleus and nano-particle → aggregation growth of nano-particle → coalescence growth of crystallite. The crystal habits of X-zeolite are intimately related with crystallization orientation of β cage in crystal and with its coupling stability on every crystal face family.
基金supported by the National Natural Science Foundation of China (No.22278128)。
文摘Crystal habit and crystal form are critical elements in determining product properties and functions. In this work, we developed a microfluidic antisolvent crystallization technique to rapidly screen and accurately control the solid form and crystal habit of triphenylmethanol(Ph_(3)COH). This advanced technique separates the primary mixing of solutions from crystal formation(nucleation and growth) by introducing the microfluidic device, avoiding clogging in microchannels to obtain high-quality crystals. The results show that we can achieve controllable preparation of pure 2Ph_(3)COH·DMSO(DMSO solvate), pure Ph_(3)COH(form β), and mixed crystals with different mass ratios. Moreover, the microscale can prompt the DMSO solvate to grow into hexagonal sheet-like and bulk crystals. We can regulate the aspect ratio of hexagonal sheet-like crystals in binary solvents and control the crystal habit of the form β to transition between long needle-like shapes and short hexagonal prisms in DMF-H_(2)O. Meanwhile, we revealed that the solvent ratio, the antisolvent flow rate, and the initial concentration of Ph_(3)COH are the main factors affecting the solid form selectivity and morphology transition. Such a novel method would be considered as a promising technique to be extended to screen and control key crystallization parameters of other substances.
基金supported by the National Key Technology R&D Program in the 11th Five-Year Plan of China(2006BAB03A10)the guiding projects of Scientific and Technological Research and Development of Hebei Province of China(07215184).
文摘By means of constant control speed cooling crystallization,the influences of four additives,including lead chloride,cadmium chloride,sodium salicylate,and quaternary ammonium salt,on the crystal habit of KCl were investigated.The results show that the crystal habit of KCl is cube without additives,the crystal habit of KCl is ellipsoid-like in the presence of Pb^(2+),the crystal habit of KCl is strip in the presence of Cd^(2+),and the crystal habit of KCl is cavate cube in the presence of sodium salicylate.Xray diffractometry analysis reveals that these additives can change the crystal habit of KCl but not its crystal structure.
文摘6-aminopenicillanic acid (6-APA) crystals obtained under different physical and chemical conditions of the solutions may present different habits. The habits of diamond-shaped plates are desirable compared with other habits of 6-APA crystals. To obtain ideal 6-APA crystals, the effects of the mixed solvents and additives on 6-APA crystal habits were investigated. Ethanol or acetone was used as the organic solvent, and impurities existing in the 6-APA purification process were used as the additives. 6-APA growth habits were changed when the concentrations of ethanol, acetone or phenyl acetic acid were increased to exceed their critical concentration. The observed results show that the dominant face on 6-APA crystals was identified to be {020}, but the overall habit was controlled by the relative growth rates of the {101} and {002} faces. Crystal growth rates and habits can be appreciably changed by specific adsorption of additives on crystal faces.In some cases solvent molecules can act in a similar way and may be regarded as bulk additives. The effects of additives and organic solvents on 6-APA crystal habits were the results of adsorption effect, which fitted the experimental results quite well.
基金Supported by EPSRC,the UK Research Council(No. GRIR 6 5 787)
文摘A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a self-consistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects(such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.
基金supported by the Major National Science and Technology Projects (No. 2017ZX07402003)Major National Scientifi c Instrument Development Project (No. 21527812)
文摘Batch crystallization in acidic aqueous solution of cephalexin was conducted by reactive crystallization with or without seeding. Supersaturation was generated by mixing ammonia and acidic aqueous solution of cephalexin and controlled by solution feeding rate and seeding conditions. UV and Morphologi G3 were used to measure supersaturation and aspect ratio. Experimental results demonstrated that burst nucleation occurred and the products were needle-like at high supersaturation;meanwhile, the products were plate-like and had high aspect ratio at low supersaturation. Analysis of the measured supersaturation profi les and corresponding aspect ratio explained the mechanisms governing the aspect ratio. The optimized operating parameters were also proposed (seeding supersaturation is equal to 1.3, seed mass ratio 8% and feeding rate 368 μL/min).
基金Funded by the National Natural Science Foundation of China(No.51272207)
文摘The growth habit of the basic magnesium oxysulfate whisker was investigated based on the theoreticalmodelof anion coordination polyhedron growth units.It is found that typicalbasic magnesium oxysulfate whisker growth is consistent with anion tetrahedralcoordination incorporation rules.The growth units of basic magnesium oxysulfate whiskers are [Mg-(OH)_4]^(2-) and HSO_4^-.[Mg-(OH)_4]^(2-) is the favorable growth unit and whisker growth is in the direction of the [Mg-(OH)_4]^(2-) combination.A plurality of [Mg-(OH)_4]^(2-) s combine and become a larger dimensionalgrowth unit in a one-dimensionaldirection.Then HSO_4^- and larger dimensionalgrowth units connect as basic magnesium sulfate whiskers,according to the structuralcharacteristics of the basic magnesium sulfate whisker,which can guide the synthesis of magnesium hydroxide whisker.