Surfactant-modified CeO_(2)@TiO_(2) core-shell nanostructure catalysts were prepared by coprecipitation with the addition of sodium dodecyl sulfonate(SDS),and their catalytic oxidation of dichloromethane(DCM) was stud...Surfactant-modified CeO_(2)@TiO_(2) core-shell nanostructure catalysts were prepared by coprecipitation with the addition of sodium dodecyl sulfonate(SDS),and their catalytic oxidation of dichloromethane(DCM) was studied.A 90% DCM conversion efficiency is obtained at 300℃ with the CeO_(2)@TiO_(2)SDS catalyst,and its catalytic stability in the 55 h test period is better than that of Ce/TiO_(2) and CeO_(2)@TiO_(2).Based on the characterization of CeO_(2)@TiO_(2)SDS,the dispersion of active components is promoted due to the inhibition of crystal growth with the introduction of SDS.The improvement of surface acidity and redox capacity is beneficial to the enhancement of catalytic activity.The higher adsorbed oxygen content on the surface of the CeO_(2)@TiO_(2)SDS catalyst is responsible for the better catalytic stability.Generally,a novel method was developed to design catalytic oxidation catalysts for the treatment of chlorinated volatile organic compounds in future applications.展开更多
The interaction between free surface flow and structure is investigated using a new level set immersed boundary method.The incorporation of an improved immersed boundary method with a free surface capture scheme imple...The interaction between free surface flow and structure is investigated using a new level set immersed boundary method.The incorporation of an improved immersed boundary method with a free surface capture scheme implemented in a Navier-Stokes solver allows the interaction between fluid flow with free surface and moving body/bodies of almost arbitrary shape to be modelled.A new algorithm is proposed to locate exact forcing points near solid boundaries,which provides an accurate numerical solution.The discretized linear system of the Poisson pressure equation is solved using the Generalized Minimum Residual(GMRES)method with incomplete LU preconditioning.Uniform flow past a cylinder at Reynolds number Re=100 is modelled using the present model and results agree well with the experiment and numerical data in the literature.Water exit and entry of a cylinder at the prescribed velocity is also investigated.The predicted slamming coefficient is in good agreement with experimental data and previous numerical simulations using a ComFlow model.The vertical slamming force and pressure distribution for the free falling wedge is also studied by the present model and comparisons with available theoretical solutions and experimental data are made.展开更多
MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs with regulatory functions. Traditionally, miRNAs are thought to play a negative regulatory role in the cytoplasm by binding to the YUTR of target genes to...MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs with regulatory functions. Traditionally, miRNAs are thought to play a negative regulatory role in the cytoplasm by binding to the YUTR of target genes to degrade mRNA or inhibit translation. However, it remains a challenge to interpret the potential function of many miRNAs located in the nucleus. Recently, we reported a new type of miRNAs present in the nucleus, which can activate gene expres- sion by binding to the enhancer, and named them nuclear activating miRNAs (NamiRNAs). The discovery of NamiRNAs showcases a complementary regulatory mechanism of miRNA, demon- strating their differential roles in the nucleus and cytoplasm. Here, we reviewed miRNAs in nucleus to better understand the function of NamiRNAs in their interactions with the enhancers. Accord- ingly, we propose a NamiRNA--enhancer-target gene activation network model to better under- stand the crosstalk between NamiRNAs and enhancers in regulating gene transcription. Moreover, we hypothesize that NamiRNAs may be involved in cell identity or cell fate determina- tion during development, although further study is needed to elucidate the underlying mechanisms in detail.展开更多
A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene.To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts,a series of different Si/Al ZSM...A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene.To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts,a series of different Si/Al ZSM-5 zeolites and catalysts doped with Na were synthesized.The experimental results show that 0.71 wt%Na+can inhibit active growth,generate more active small crystal grains,and promote improvement of the catalytic activity by the grain boundary segregation block mechanism,and the catalyst with 0.71 wt%of Na shows toluene conversion of 90 vol%at 250℃.Over 0.71 wt%of Na+content will neutralize the acid centre of the catalyst,lowering the specific surface area of the catalyst and resulting in a gradual decrease in the catalytic activity.展开更多
We present a three dimensional preconditioned implicit free-surface capture scheme on tetrahedral grids.The current scheme improves our recently reported method[10]in several aspects.Specifically,we modified the origi...We present a three dimensional preconditioned implicit free-surface capture scheme on tetrahedral grids.The current scheme improves our recently reported method[10]in several aspects.Specifically,we modified the original eigensystem by applying a preconditioning matrix so that the new eigensystem is virtually independent of density ratio,which is typically large for practical two-phase problems.Further,we replaced the explicit multi-stage Runge-Kutta method by a fully implicit Euler integration scheme for the Navier-Stokes(NS)solver and the Volume of Fluids(VOF)equation is now solved with a second order Crank-Nicolson implicit scheme to reduce the numerical diffusion effect.The preconditioned restarted GeneralizedMinimal RESidual method(GMRES)is then employed to solve the resulting linear system.The validation studies show that with these modifications,the method has improved stability and accuracy when dealing with large density ratio two-phase problems.展开更多
基金Project supported by the Science and Technology Department of Jiangsu Province (BE2016769)the Natural Science Foundation of Jiangsu Province (BK20171466 and BK20180718)。
文摘Surfactant-modified CeO_(2)@TiO_(2) core-shell nanostructure catalysts were prepared by coprecipitation with the addition of sodium dodecyl sulfonate(SDS),and their catalytic oxidation of dichloromethane(DCM) was studied.A 90% DCM conversion efficiency is obtained at 300℃ with the CeO_(2)@TiO_(2)SDS catalyst,and its catalytic stability in the 55 h test period is better than that of Ce/TiO_(2) and CeO_(2)@TiO_(2).Based on the characterization of CeO_(2)@TiO_(2)SDS,the dispersion of active components is promoted due to the inhibition of crystal growth with the introduction of SDS.The improvement of surface acidity and redox capacity is beneficial to the enhancement of catalytic activity.The higher adsorbed oxygen content on the surface of the CeO_(2)@TiO_(2)SDS catalyst is responsible for the better catalytic stability.Generally,a novel method was developed to design catalytic oxidation catalysts for the treatment of chlorinated volatile organic compounds in future applications.
基金the support of the South West of England Regional Development Agency in funding this project through Peninsular Research Institute for Marine Renewable Energy(http://www.primare.org/).
文摘The interaction between free surface flow and structure is investigated using a new level set immersed boundary method.The incorporation of an improved immersed boundary method with a free surface capture scheme implemented in a Navier-Stokes solver allows the interaction between fluid flow with free surface and moving body/bodies of almost arbitrary shape to be modelled.A new algorithm is proposed to locate exact forcing points near solid boundaries,which provides an accurate numerical solution.The discretized linear system of the Poisson pressure equation is solved using the Generalized Minimum Residual(GMRES)method with incomplete LU preconditioning.Uniform flow past a cylinder at Reynolds number Re=100 is modelled using the present model and results agree well with the experiment and numerical data in the literature.Water exit and entry of a cylinder at the prescribed velocity is also investigated.The predicted slamming coefficient is in good agreement with experimental data and previous numerical simulations using a ComFlow model.The vertical slamming force and pressure distribution for the free falling wedge is also studied by the present model and comparisons with available theoretical solutions and experimental data are made.
基金supported by the National Natural Science Foundation of China (Grant No. 31671308)the Ministry of Science and Technology of China (Grant No. 2016YFC0900300)
文摘MicroRNAs (miRNAs) are a class of endogenous non-coding RNAs with regulatory functions. Traditionally, miRNAs are thought to play a negative regulatory role in the cytoplasm by binding to the YUTR of target genes to degrade mRNA or inhibit translation. However, it remains a challenge to interpret the potential function of many miRNAs located in the nucleus. Recently, we reported a new type of miRNAs present in the nucleus, which can activate gene expres- sion by binding to the enhancer, and named them nuclear activating miRNAs (NamiRNAs). The discovery of NamiRNAs showcases a complementary regulatory mechanism of miRNA, demon- strating their differential roles in the nucleus and cytoplasm. Here, we reviewed miRNAs in nucleus to better understand the function of NamiRNAs in their interactions with the enhancers. Accord- ingly, we propose a NamiRNA--enhancer-target gene activation network model to better under- stand the crosstalk between NamiRNAs and enhancers in regulating gene transcription. Moreover, we hypothesize that NamiRNAs may be involved in cell identity or cell fate determina- tion during development, although further study is needed to elucidate the underlying mechanisms in detail.
基金Project supported by Science and Technology Department of Jiangsu Province(BE2016769).
文摘A CoCe/ZSM-5 catalyst was prepared by ultrasonic-assisted impregnation for the catalytic combustion of toluene.To study the effect of Na+on catalytic performance of CoCe/ZSM-5 catalysts,a series of different Si/Al ZSM-5 zeolites and catalysts doped with Na were synthesized.The experimental results show that 0.71 wt%Na+can inhibit active growth,generate more active small crystal grains,and promote improvement of the catalytic activity by the grain boundary segregation block mechanism,and the catalyst with 0.71 wt%of Na shows toluene conversion of 90 vol%at 250℃.Over 0.71 wt%of Na+content will neutralize the acid centre of the catalyst,lowering the specific surface area of the catalyst and resulting in a gradual decrease in the catalytic activity.
基金supported by the Flood Risk from Extreme Events(FREE)Programme of the UK Natural Environment Research Council(NERC)(NE/E0002129/1)coordinated and monitored by Professor Chris Collier and Paul Hardaker.We thank Dr.Zhengyi Wang and Dr.Qun Zhao for helpful discussions.The numerical calculations have been carried out on the HPC facility at the University of Plymouth.
文摘We present a three dimensional preconditioned implicit free-surface capture scheme on tetrahedral grids.The current scheme improves our recently reported method[10]in several aspects.Specifically,we modified the original eigensystem by applying a preconditioning matrix so that the new eigensystem is virtually independent of density ratio,which is typically large for practical two-phase problems.Further,we replaced the explicit multi-stage Runge-Kutta method by a fully implicit Euler integration scheme for the Navier-Stokes(NS)solver and the Volume of Fluids(VOF)equation is now solved with a second order Crank-Nicolson implicit scheme to reduce the numerical diffusion effect.The preconditioned restarted GeneralizedMinimal RESidual method(GMRES)is then employed to solve the resulting linear system.The validation studies show that with these modifications,the method has improved stability and accuracy when dealing with large density ratio two-phase problems.