Cerium-promoted silica supported copper chromite catalyst was synthesized from acid hydrolysis of sodium silicate by sol-gel method.The catalyst was characterized by Brunauer-Emmett-Teller(BET)method,field-emission sc...Cerium-promoted silica supported copper chromite catalyst was synthesized from acid hydrolysis of sodium silicate by sol-gel method.The catalyst was characterized by Brunauer-Emmett-Teller(BET)method,field-emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH3-temperature programmed desorption(NH3-TPD)and pyridine adsorbed Fourier transform infrared spectroscopy(Py-FTIR).Among cerium doped catalysts,5 wt%of Ce promoted copper chromite supported by 40 wt%of silica(SiCuCr40-Ce5)shows the largest BET surface area.XRD analysis of the reduced form of the catalyst shows both CeO_(2)/Ce_(2)O_(3) redox system and CuO/Cu_(2)O/Cu redox system.Py-FTIR shows the maximum number of Lewis acid sites for SiCuCr40-Ce5 than others.The highest acetol selectivity with analytical reagent(AR)grade glycerol conversion is observed for SiCuCr40-Ce5 at 200℃for 3 h in a batch reactor at atmospheric pressure.Cerium promotion lowers the reaction te mperature with enhanced glycerol conve rsion and increased acetol selectivity.Though the above catalyst shows higher conversion for laboratory reagent(LR)grade glycerol but it reduces acetol selectivity.The addition of glucose into the LR grade glycerol further reduces glycerol conversion and decreases the acetol selectivity to zero.This may be due to the presence of iron as impurity in LR grade glycerol.XRD analysis of spent catalyst shows the absence of redox catalytic system and the pore volume reduces identified by BET analysis.Raman analysis of the spent catalyst shows graphite-like carbon deposition in the spent catalvst.展开更多
A representation for the velocity and pressure fields in three-dimensional Stokes flow was presented in terms of a biharmonic function A and a harmonic function B.This representation was used to establish a general th...A representation for the velocity and pressure fields in three-dimensional Stokes flow was presented in terms of a biharmonic function A and a harmonic function B.This representation was used to establish a general theorem for the calculation of Stokes flow due to fundamental singularities in a region bounded by a stationary no-slip plane boundary.Collins's theorem for axisymmetric Stokes flow before a rigid plane follows as a special case of the theorem.A few illustrative examples are given to show its usefulness.展开更多
A general theorem for the Stokes flow over a plane boundary with mixed stick-slip boundary conditions is established. This is done by using a representation for the velocity and pressure fields in the three-dimensiona...A general theorem for the Stokes flow over a plane boundary with mixed stick-slip boundary conditions is established. This is done by using a representation for the velocity and pressure fields in the three-dimensional Stokes flow in terms of a biharmonic function and a harmonic function. The earlier theorem for the Stokes flow due to fundamental singularities before a no-slip plane boundary is shown to be a special case of the present theorem. Furthermore, in terms of the Stokes stream function, a corollary of the theorem is also derived, providing a solution to the problem of the axisymmetric Stokes flow along a rigid plane with stick-slip boundary conditions. The formulae for the drag and torque exerted by the fluid on the boundary are established. An illustrative example is given.展开更多
Following the bioautographic te-chnique, 24 lysine producing microor-ganisms have been isolated from amongthe 263 hydrocarbon utilisers. Morphological, cultural and biochemicalcharacters of two promising isolates,have...Following the bioautographic te-chnique, 24 lysine producing microor-ganisms have been isolated from amongthe 263 hydrocarbon utilisers. Morphological, cultural and biochemicalcharacters of two promising isolates,have been studied. One of them iden-tified as Arthrobacter globiformis andthe other as Micrococcus varians, pro-duce 3.4 and 2.6 g lysine per litreof medium.展开更多
Hollow needle array-based tissue nanotransfection(TNT)presents an in vivo transfection approach that directly translocate exogeneous genes to target tissues by using electric pulses.In this work,the gene delivery proc...Hollow needle array-based tissue nanotransfection(TNT)presents an in vivo transfection approach that directly translocate exogeneous genes to target tissues by using electric pulses.In this work,the gene delivery process of TNT was simulated and experimentally validated.We adopted the asymptotic method and cell-array-based model to investigate the electroporation behaviors of cells within the skin structure.The distribution of nonuniform electric field across the skin results in various electroporation behavior for each cell.Cells underneath the hollow microchannels of the needle exhibited the highest total pore numbers compared to others due to the stronger localized electric field.The percentage of electroporated cells within the skin structure,with pore radius over 10 nm,increases from 25%to 82%as the applied voltage increases from 100 to 150 V/mm.Furthermore,the gene delivery behavior across the skin tissue was investigated through the multilayer-stack-based model.The delivery distance increased nonlinearly as the applied voltage and pulse number increased,which mainly depends on the diffusion characteristics and electric conductivity of each layer.It was also found that the skin is required to be exfoliated prior to the TNT procedure to enhance the delivery depth.This work provides the foundation for transition from the study of murine skin to translation use in large animals and human settings.展开更多
文摘Cerium-promoted silica supported copper chromite catalyst was synthesized from acid hydrolysis of sodium silicate by sol-gel method.The catalyst was characterized by Brunauer-Emmett-Teller(BET)method,field-emission scanning electron microscopy(FESEM),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH3-temperature programmed desorption(NH3-TPD)and pyridine adsorbed Fourier transform infrared spectroscopy(Py-FTIR).Among cerium doped catalysts,5 wt%of Ce promoted copper chromite supported by 40 wt%of silica(SiCuCr40-Ce5)shows the largest BET surface area.XRD analysis of the reduced form of the catalyst shows both CeO_(2)/Ce_(2)O_(3) redox system and CuO/Cu_(2)O/Cu redox system.Py-FTIR shows the maximum number of Lewis acid sites for SiCuCr40-Ce5 than others.The highest acetol selectivity with analytical reagent(AR)grade glycerol conversion is observed for SiCuCr40-Ce5 at 200℃for 3 h in a batch reactor at atmospheric pressure.Cerium promotion lowers the reaction te mperature with enhanced glycerol conve rsion and increased acetol selectivity.Though the above catalyst shows higher conversion for laboratory reagent(LR)grade glycerol but it reduces acetol selectivity.The addition of glucose into the LR grade glycerol further reduces glycerol conversion and decreases the acetol selectivity to zero.This may be due to the presence of iron as impurity in LR grade glycerol.XRD analysis of spent catalyst shows the absence of redox catalytic system and the pore volume reduces identified by BET analysis.Raman analysis of the spent catalyst shows graphite-like carbon deposition in the spent catalvst.
文摘A representation for the velocity and pressure fields in three-dimensional Stokes flow was presented in terms of a biharmonic function A and a harmonic function B.This representation was used to establish a general theorem for the calculation of Stokes flow due to fundamental singularities in a region bounded by a stationary no-slip plane boundary.Collins's theorem for axisymmetric Stokes flow before a rigid plane follows as a special case of the theorem.A few illustrative examples are given to show its usefulness.
文摘A general theorem for the Stokes flow over a plane boundary with mixed stick-slip boundary conditions is established. This is done by using a representation for the velocity and pressure fields in the three-dimensional Stokes flow in terms of a biharmonic function and a harmonic function. The earlier theorem for the Stokes flow due to fundamental singularities before a no-slip plane boundary is shown to be a special case of the present theorem. Furthermore, in terms of the Stokes stream function, a corollary of the theorem is also derived, providing a solution to the problem of the axisymmetric Stokes flow along a rigid plane with stick-slip boundary conditions. The formulae for the drag and torque exerted by the fluid on the boundary are established. An illustrative example is given.
文摘Following the bioautographic te-chnique, 24 lysine producing microor-ganisms have been isolated from amongthe 263 hydrocarbon utilisers. Morphological, cultural and biochemicalcharacters of two promising isolates,have been studied. One of them iden-tified as Arthrobacter globiformis andthe other as Micrococcus varians, pro-duce 3.4 and 2.6 g lysine per litreof medium.
基金This work was supported in part by National Institutes of Health(NIH)grant(No.DK128845)Department of Defense grant(Nos.W81XWH-21-1-0097,W81XWH-21-1-0033,and W81XWH-20-1-251)to C.K.S,NIH grant(No.GM143572)to Y.X,and NIH grant(No.DK129592)to S.G.
文摘Hollow needle array-based tissue nanotransfection(TNT)presents an in vivo transfection approach that directly translocate exogeneous genes to target tissues by using electric pulses.In this work,the gene delivery process of TNT was simulated and experimentally validated.We adopted the asymptotic method and cell-array-based model to investigate the electroporation behaviors of cells within the skin structure.The distribution of nonuniform electric field across the skin results in various electroporation behavior for each cell.Cells underneath the hollow microchannels of the needle exhibited the highest total pore numbers compared to others due to the stronger localized electric field.The percentage of electroporated cells within the skin structure,with pore radius over 10 nm,increases from 25%to 82%as the applied voltage increases from 100 to 150 V/mm.Furthermore,the gene delivery behavior across the skin tissue was investigated through the multilayer-stack-based model.The delivery distance increased nonlinearly as the applied voltage and pulse number increased,which mainly depends on the diffusion characteristics and electric conductivity of each layer.It was also found that the skin is required to be exfoliated prior to the TNT procedure to enhance the delivery depth.This work provides the foundation for transition from the study of murine skin to translation use in large animals and human settings.
