Hydrogen energy,as the ultimate clean energy,effectively avoids the greenhouse effect.Chemical looping hydrogen production(CLHP),a versatile energy conversion and production technology,has garnered extensive attention...Hydrogen energy,as the ultimate clean energy,effectively avoids the greenhouse effect.Chemical looping hydrogen production(CLHP),a versatile energy conversion and production technology,has garnered extensive attention.CLHP demands redox catalysts with high oxygen capacity,regulatable reactivity,and structural integrity even under harsh operational conditions.Currently,sintering,agglomeration,and inactivation of redox catalysts during cyclic lattice oxygen release and restoration are challenging,hindering the wide industrialization of the chemical looping(CL)process.Moreover,the precise control of activity and reaction rate of the redox catalysts to flexibly accommodate the demands of various reaction substrates remains unclear.This paper introduces the design of a nano-scaled redox catalyst featuring a unique core-shell structure.By precisely controlling the shell thickness,a series of hierarchical Fe_(2)O_(3)@SiO_(2)redox catalysts were successfully synthesized.Building on this achievement,an in-depth investigation was conducted into the impact of the thickness and spatial structure of the inert support on the stability and mass transfer rate of the redox catalyst,aiming to achieve a perfect balance between these two factors during the CLHP process.A thin shell(70 nm)exhibits excellent cyclic stability,maintaining consistent performance in 30 consecutive redox cycles,while a thicker shell(200 nm)undergoes rapid deactivation due to the formation of a substantial amount of iron silicate.In-situ transmission electron microscopy(TEM)reveals that the SiO_(2)shell effectively restricts the agglomeration of Fe_(2)O_(3).The unique core-shell structure and controllable shell thickness offer novel insights into the flexible design of efficient and durable hierarchical redox catalysts with spatial structure.展开更多
The current healthcare system in Hong Kong is experiencing pressure due to constrained resources,with dramatic increases in inpatient services queue lengths,dissatisfaction with the working environment,unacceptable wo...The current healthcare system in Hong Kong is experiencing pressure due to constrained resources,with dramatic increases in inpatient services queue lengths,dissatisfaction with the working environment,unacceptable workforce arrangements and high turnover rate of hospital staff.To maintain the robustness of the healthcare system and a sustainable inpatients flow,the Food and Health Bureau launched a public-private partnership programme to utilise the resources of the public and private hospitals.This research investigates the potential for extension of the programme and further enhancing the sustainability of the long-term inpatient services under a mixed public-private healthcare policy via system dynamic modelling.The findings show that an increase of human resources in public hospitals does not substantially improve inpatient flow rate performance.Further,the results from the system dynamic approach provide insights into the expansion of the service areas of the programme and suggest increasing the number of referrals to private hospitals.展开更多
基金financial support from the National Natural Science Foundation of China(52076209,22179027,22469006)the Foundation and Applied Foundation Research of Guangdong Province(2022B1515020045)the Heilongjiang Key Research and Development Project of China(JD22A026)。
文摘Hydrogen energy,as the ultimate clean energy,effectively avoids the greenhouse effect.Chemical looping hydrogen production(CLHP),a versatile energy conversion and production technology,has garnered extensive attention.CLHP demands redox catalysts with high oxygen capacity,regulatable reactivity,and structural integrity even under harsh operational conditions.Currently,sintering,agglomeration,and inactivation of redox catalysts during cyclic lattice oxygen release and restoration are challenging,hindering the wide industrialization of the chemical looping(CL)process.Moreover,the precise control of activity and reaction rate of the redox catalysts to flexibly accommodate the demands of various reaction substrates remains unclear.This paper introduces the design of a nano-scaled redox catalyst featuring a unique core-shell structure.By precisely controlling the shell thickness,a series of hierarchical Fe_(2)O_(3)@SiO_(2)redox catalysts were successfully synthesized.Building on this achievement,an in-depth investigation was conducted into the impact of the thickness and spatial structure of the inert support on the stability and mass transfer rate of the redox catalyst,aiming to achieve a perfect balance between these two factors during the CLHP process.A thin shell(70 nm)exhibits excellent cyclic stability,maintaining consistent performance in 30 consecutive redox cycles,while a thicker shell(200 nm)undergoes rapid deactivation due to the formation of a substantial amount of iron silicate.In-situ transmission electron microscopy(TEM)reveals that the SiO_(2)shell effectively restricts the agglomeration of Fe_(2)O_(3).The unique core-shell structure and controllable shell thickness offer novel insights into the flexible design of efficient and durable hierarchical redox catalysts with spatial structure.
基金Research Committee and the Department of Industrial and Systems Engineering of the Hong Kong Polytechnic University for supporting this project(G-UA7X).
文摘The current healthcare system in Hong Kong is experiencing pressure due to constrained resources,with dramatic increases in inpatient services queue lengths,dissatisfaction with the working environment,unacceptable workforce arrangements and high turnover rate of hospital staff.To maintain the robustness of the healthcare system and a sustainable inpatients flow,the Food and Health Bureau launched a public-private partnership programme to utilise the resources of the public and private hospitals.This research investigates the potential for extension of the programme and further enhancing the sustainability of the long-term inpatient services under a mixed public-private healthcare policy via system dynamic modelling.The findings show that an increase of human resources in public hospitals does not substantially improve inpatient flow rate performance.Further,the results from the system dynamic approach provide insights into the expansion of the service areas of the programme and suggest increasing the number of referrals to private hospitals.
