NaA zeolite membranes were prepared by secondary growth method on the outer surface of α-Al2O3 hollow fiber supports. Vacuum seeding method was used for planting zeolite seeds on the support surfaces. Hydrothermal cr...NaA zeolite membranes were prepared by secondary growth method on the outer surface of α-Al2O3 hollow fiber supports. Vacuum seeding method was used for planting zeolite seeds on the support surfaces. Hydrothermal crystallization was then carried out in a synthesis solution with molar ratio of Al2O3：SiO2：Na2O：H2O = 1：2：2：120 at 100 ℃ for 4 h. Effects of seeding conditions on preparation of hollow fiber NaA zeolite membranes were extensively investigated. Moreover, hollow fiber membrane modules with packing membrane areas of ca. 0.1 and 0.2 m2 were fabricated to separate ethanol/water mixture. It is found that the thickness of seed layer is obviously affected by seed suspension concentration, coating time and vacuum degree. Close-packing seed layer is required to obtain high-quality membranes. The optimized seeding conditions （seed suspension mass concentration of 0.5%-0.7% coating time of 5 s and vacuum degree of 10 kPa） lead to dense NaA zeolite layer with a thickness of 6-8 gin. Typically, an as-synthesized hollow fiber NaA zeolite membrane exhibits good pervaporation performance with a permeation flux of 7.02 kg· m^- 2· h^- 1 and separation factor 〉 10000 for sepa- ration of 90%; （by mass） ethanol/water mixture at 75 ℃ High reproducibility has been achieved for batch-scale production of hollow fiber NaA zeolite membranes by the hydrothermal synthesis approach.展开更多
The grain boundaries and interface properties in the active layers of perovskite solar cells(PSCs)are important factors affecting the performances of the devices.In this work,a simple and fast concomitant annealing pr...The grain boundaries and interface properties in the active layers of perovskite solar cells(PSCs)are important factors affecting the performances of the devices.In this work,a simple and fast concomitant annealing process is established by inducing the secondary growth of the grains using the anti-solvent o-dichlorobenzene(o-PhCl2)or chlorobenzene(PhCl)to suppress the volatilization of solvent molecules during the FA0.80MA0.15Cs0.05Pb(I0.85Br0.15)3(FA,CH5N2+,formamidine;MA,CH3NH3+,methylamine)film annealing procedure.The effects of anti-solvent molecules on the phase transformation,grain boundary fusion and morphology evolution of perovskite films are systematically investigated by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results indicate that anti-solvent molecules can inhibit solvent evaporation in the active layers and promote crystallite dissolution and ordered secondary growth along the surfaces of large grains.That can promote the formation of large grains and the passivation of surface defects,and can be favorable for the separation and transportation of photocarriers in the active layer.Consequently,the power conversion efficiency(PCE)of PSCs can be effectively improved,with a PCE of 20.72%being achieved by a secondary growth perovskite film optimized with o-PhCl2.Moreover,the efficiency remains at 85%of its initial value after 2400 h of treatment in a natural indoor environment with a relative humidity of 45±5%.展开更多
We investigate a generalized form of the Boussinesq equation, relevant for nerve pulse propagation in biological membranes. The generalized conditional symmetry （GCS） method is applied in order to obtain the conditi...We investigate a generalized form of the Boussinesq equation, relevant for nerve pulse propagation in biological membranes. The generalized conditional symmetry （GCS） method is applied in order to obtain the conditions that enable the equation to admit a special class of second-order GCSs. For the case of quadratic nonlinearities, we outline a new class of invariant solutions.展开更多
基金Supported by the National Basic Research Program of China(2009CB623403)the National Natural Science Foundation of China(21176117,21222602)+3 种基金the Key Project of Chinese Ministry of Education(212060)the Outstanding Young Fund of Jiangsu Province(BK2012040)the"Six Top Talents"of Jiangsu Province,the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(09KJA530002)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘NaA zeolite membranes were prepared by secondary growth method on the outer surface of α-Al2O3 hollow fiber supports. Vacuum seeding method was used for planting zeolite seeds on the support surfaces. Hydrothermal crystallization was then carried out in a synthesis solution with molar ratio of Al2O3：SiO2：Na2O：H2O = 1：2：2：120 at 100 ℃ for 4 h. Effects of seeding conditions on preparation of hollow fiber NaA zeolite membranes were extensively investigated. Moreover, hollow fiber membrane modules with packing membrane areas of ca. 0.1 and 0.2 m2 were fabricated to separate ethanol/water mixture. It is found that the thickness of seed layer is obviously affected by seed suspension concentration, coating time and vacuum degree. Close-packing seed layer is required to obtain high-quality membranes. The optimized seeding conditions （seed suspension mass concentration of 0.5%-0.7% coating time of 5 s and vacuum degree of 10 kPa） lead to dense NaA zeolite layer with a thickness of 6-8 gin. Typically, an as-synthesized hollow fiber NaA zeolite membrane exhibits good pervaporation performance with a permeation flux of 7.02 kg· m^- 2· h^- 1 and separation factor 〉 10000 for sepa- ration of 90%; （by mass） ethanol/water mixture at 75 ℃ High reproducibility has been achieved for batch-scale production of hollow fiber NaA zeolite membranes by the hydrothermal synthesis approach.
基金the National Natural Science Foundation of China(21676188)the Science and Technology Plan Project of Tianjin(19ZXNCGX00020)the National Key R&D Program of China(2016YFB0401303)。
文摘The grain boundaries and interface properties in the active layers of perovskite solar cells(PSCs)are important factors affecting the performances of the devices.In this work,a simple and fast concomitant annealing process is established by inducing the secondary growth of the grains using the anti-solvent o-dichlorobenzene(o-PhCl2)or chlorobenzene(PhCl)to suppress the volatilization of solvent molecules during the FA0.80MA0.15Cs0.05Pb(I0.85Br0.15)3(FA,CH5N2+,formamidine;MA,CH3NH3+,methylamine)film annealing procedure.The effects of anti-solvent molecules on the phase transformation,grain boundary fusion and morphology evolution of perovskite films are systematically investigated by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results indicate that anti-solvent molecules can inhibit solvent evaporation in the active layers and promote crystallite dissolution and ordered secondary growth along the surfaces of large grains.That can promote the formation of large grains and the passivation of surface defects,and can be favorable for the separation and transportation of photocarriers in the active layer.Consequently,the power conversion efficiency(PCE)of PSCs can be effectively improved,with a PCE of 20.72%being achieved by a secondary growth perovskite film optimized with o-PhCl2.Moreover,the efficiency remains at 85%of its initial value after 2400 h of treatment in a natural indoor environment with a relative humidity of 45±5%.
文摘We investigate a generalized form of the Boussinesq equation, relevant for nerve pulse propagation in biological membranes. The generalized conditional symmetry （GCS） method is applied in order to obtain the conditions that enable the equation to admit a special class of second-order GCSs. For the case of quadratic nonlinearities, we outline a new class of invariant solutions.
