More and more researchers have paid attention to Taylor-Couette flow whose axial dimension is much larger than other dimensions.However,featured by the limited axial length of the bearing,its flow field and convective...More and more researchers have paid attention to Taylor-Couette flow whose axial dimension is much larger than other dimensions.However,featured by the limited axial length of the bearing,its flow field and convective heat transfer between the rotator and the stator are highly conglutinated with the leakage at the end of the clearance.An investigation was conducted on the flow field and convective heat transfer of small-scale Taylor-Couette flow induced by end leakage through means of numerical simulation and experimental measurement.The static pressure and temperature of the stator were captured by a micromanometer and a time-resolved infrared camera,respectively.Large Eddy Simulation(LES)was performed to reveal the instantaneous and mean flow field of the shearing flow.Results show that the flow field and convective heat transfer are tightly associated with the presence of end leakage.As approaching the end of the clearance,the flow is dominated by the axial flow induced by the end leakage,and then a series of Taylor vortices gradually distorts and tilts as moving downstream.Along the angular direction,the maximum and minimum static pressures take place near minimum clearance height,respectively.The static pressure along the angular direction and the axial velocity near the minimum clearance height as well as the Nusselt number increase with increases of the rotational Reynolds number and the eccentricity ratio while decreasing with an increase of the dimensionless clearance height.Both natural convection by buoyancy and forced convection by the shearing flow play a significant role in convective heat transfer.Compared with classic Taylor-Couette flow,the occurrence of leakage decreases the maximum static pressure while increasing the minimum static pressure.The formation and evolution of the Taylor vortex are dominated by the axial flow.展开更多
Recently,tissue engineering has developed into a powerful tool for repairing and reconstructing damaged tissues and organs.Tissue engineering scaffolds play a vital role in tissue engineering,as they not only provide ...Recently,tissue engineering has developed into a powerful tool for repairing and reconstructing damaged tissues and organs.Tissue engineering scaffolds play a vital role in tissue engineering,as they not only provide structural support for targeted cells but also serve as templates that guide tissue regeneration and control the tissue structure.Over the past few years,owing to unique physicochemical properties and excellent biocompatibility,various types of two-dimensional(2D)nanomaterials have been developed as candidates for the construction of tissue engineering scaffolds,enabling remarkable achievements in bone repair,wound healing,neural regeneration,and cardiac tissue engineering.These efforts have significantly advanced the development of tissue engineering.In this review,we summarize the latest advancements in the application of 2D nanomaterials in tissue engineering.First,each typical 2D nanomaterial is introduced briefly,followed by a detailed description of its applications in tissue engineering.Finally,the existing challenges and prospects for the future of the application of 2D nanomaterials in tissue engineering are discussed.展开更多
Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials.Nonetheless,it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalit...Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials.Nonetheless,it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalities that are needed for practical artificial skin applications,i.e.,to be biocompatible,strain-sensitive,ion-conductive,elastic and robust,anti-swelling,and anti-freezing.Here we present a such type of versatile hydrogel that is not only capable to deliver all the above-mentioned key functionalities but also highly stable.This novel hydrogel is constructed by introducing a gelatinous and amorphous multi-ionic biomineral(denoted as Mg-ACCP,containing Mg^(2+),Ca^(2+),CO_(3)^(2−),and PO_(4)^(3−))into the network of biocompatible polyvinyl alcohol(PVA)and sodium alginate(SA).The presence of Mg^(2+)and PO_(4)^(3−)in this hydrogel helps prohibit the crystallization of the biominerals,leading to significantly improved stability.The hydrogel thus obtained delivers excellent mechanical performance due to the chelation between the mineral ions and the organic matrix,and high sensitivity even to subtle pressure and strain applied,such as slight finger bending and gentle tapping.Furthermore,the novel hydrogel features high ionic conductivity,high resistance to swelling,and extraordinary anti-freezing property,holding great promise for applications in different practical scenarios,particularly in aqueous or cold environments.展开更多
Effective cancer treatment puts high demands for cancer theranostics.For cancer diagnostics,optical coherence tomography(OCT)technology(including photothermal optical coherence tomography(PT-OCT))has been widely inves...Effective cancer treatment puts high demands for cancer theranostics.For cancer diagnostics,optical coherence tomography(OCT)technology(including photothermal optical coherence tomography(PT-OCT))has been widely investigated since it induces changes in optical phase transitions in tissue through environmental changes(such as temperature change for PT-OCT).In this report,redox responsive nanoparticle encapsulating black phosphorus quantum dots was developed as a robust PT-OCT agent.Briefly,black phosphorus quantum dots(BPQDs)are incorporated into cysteine-based poly-(disulfide amide)(Cys-PDSA)to form stable and biodegradable nanoagent.The excellent photothermal feature allows BPQD/Cys-PDSA nanoparticles(NPs)as a novel contrast agent for high-resolution PT-OCT bioimaging.The Cys-PDSA can rapidly respond to glutathione and effectively release BPQDs and drugs in vitro and in vivo.And the obtained NPs exhibit excellent near-infrared(NIR)photothermal transduction efficiency and drug delivery capacity that can serve as novel therapeutic platform,with very low chemo drug dosage and side effects.Both of the polymer and BPQD are degradable,indicating this platform is a rare PT-OCT agent that is completely biodegradable.Overall,our research highlights a biodegradable and biocompatible black phosphorus-based nanoagent for both cancer diagnosis and therapy.展开更多
The dyotropic rearrangement of β-lactones is a neglected treasure in the family of multi-bond reactions and pericyclic reactions.Despite its appealing synthetic potential,the complicated migration selectivity greatly...The dyotropic rearrangement of β-lactones is a neglected treasure in the family of multi-bond reactions and pericyclic reactions.Despite its appealing synthetic potential,the complicated migration selectivity greatly limits its widespread application.In this work,we report the first systematic and comprehensive computational study on the dyotropic rearrangements of β-lactones.The use of the double-hybrid functional ensures the accuracy of results.On the basis of the present study and our previous work,five methods to control the reaction selectivity of dyotropic rearrangements of β-lactones have been summarized,providing valuable references for synthetic chemists to design and develop brand-new type dyotropic reactions.展开更多
基金The authors gratefully acknowledge the financial supports from the National Natural Science Foundation of China(Nos.51776097 and 52206091)the Aeronautical Science Foundation of China(No.201928052008)+1 种基金the Natural Science Foundation of Jiangsu Province,China(No.BK20210303)the Advanced Jet Propulsion Innovation,China(No.HKCX2022-01-001).
文摘More and more researchers have paid attention to Taylor-Couette flow whose axial dimension is much larger than other dimensions.However,featured by the limited axial length of the bearing,its flow field and convective heat transfer between the rotator and the stator are highly conglutinated with the leakage at the end of the clearance.An investigation was conducted on the flow field and convective heat transfer of small-scale Taylor-Couette flow induced by end leakage through means of numerical simulation and experimental measurement.The static pressure and temperature of the stator were captured by a micromanometer and a time-resolved infrared camera,respectively.Large Eddy Simulation(LES)was performed to reveal the instantaneous and mean flow field of the shearing flow.Results show that the flow field and convective heat transfer are tightly associated with the presence of end leakage.As approaching the end of the clearance,the flow is dominated by the axial flow induced by the end leakage,and then a series of Taylor vortices gradually distorts and tilts as moving downstream.Along the angular direction,the maximum and minimum static pressures take place near minimum clearance height,respectively.The static pressure along the angular direction and the axial velocity near the minimum clearance height as well as the Nusselt number increase with increases of the rotational Reynolds number and the eccentricity ratio while decreasing with an increase of the dimensionless clearance height.Both natural convection by buoyancy and forced convection by the shearing flow play a significant role in convective heat transfer.Compared with classic Taylor-Couette flow,the occurrence of leakage decreases the maximum static pressure while increasing the minimum static pressure.The formation and evolution of the Taylor vortex are dominated by the axial flow.
基金This work was supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2018ZX10301402)General Program of National Natural Science Foundation of China(No.51973243)+3 种基金Guangdong Innovative and Entrepreneurial Research Team Program(No.2016ZT06S029)General Program of Guangdong Natural Science Foundation(No.2020A1515010983)Science and Technology Planning Project of Shenzhen(Nos.JCYJ20170307141438157 and JCYJ20190807155801657)the Fundamental Research Funds for the Central Universities(No.191gzd35).
文摘Recently,tissue engineering has developed into a powerful tool for repairing and reconstructing damaged tissues and organs.Tissue engineering scaffolds play a vital role in tissue engineering,as they not only provide structural support for targeted cells but also serve as templates that guide tissue regeneration and control the tissue structure.Over the past few years,owing to unique physicochemical properties and excellent biocompatibility,various types of two-dimensional(2D)nanomaterials have been developed as candidates for the construction of tissue engineering scaffolds,enabling remarkable achievements in bone repair,wound healing,neural regeneration,and cardiac tissue engineering.These efforts have significantly advanced the development of tissue engineering.In this review,we summarize the latest advancements in the application of 2D nanomaterials in tissue engineering.First,each typical 2D nanomaterial is introduced briefly,followed by a detailed description of its applications in tissue engineering.Finally,the existing challenges and prospects for the future of the application of 2D nanomaterials in tissue engineering are discussed.
基金supported by Shenzhen-Hong Kong Science and Technology Innovation Cooperation Zone Shenzhen Park Project:HZQB-KCZYB-2020030Health@InnoHK(Hong Kong Centre for Cerebro-cardiovascular Health Engineering(COCHE),Innovation and Technology Commission,the Government of the Hong Kong Special Administrative Region of the People’s Republic of China,the Innovation and Technology Commission of HKSAR through Hong Kong Branch of National Precious Metals Material Engineering Research Center(NPMM),the City University of Hong Kong(No.7005077).
文摘Mineral hydrogels have caught a lot of attention for their strong competency as artificial skin-like materials.Nonetheless,it remains a great difficulty in fulfilling in one hydrogel system a range of key functionalities that are needed for practical artificial skin applications,i.e.,to be biocompatible,strain-sensitive,ion-conductive,elastic and robust,anti-swelling,and anti-freezing.Here we present a such type of versatile hydrogel that is not only capable to deliver all the above-mentioned key functionalities but also highly stable.This novel hydrogel is constructed by introducing a gelatinous and amorphous multi-ionic biomineral(denoted as Mg-ACCP,containing Mg^(2+),Ca^(2+),CO_(3)^(2−),and PO_(4)^(3−))into the network of biocompatible polyvinyl alcohol(PVA)and sodium alginate(SA).The presence of Mg^(2+)and PO_(4)^(3−)in this hydrogel helps prohibit the crystallization of the biominerals,leading to significantly improved stability.The hydrogel thus obtained delivers excellent mechanical performance due to the chelation between the mineral ions and the organic matrix,and high sensitivity even to subtle pressure and strain applied,such as slight finger bending and gentle tapping.Furthermore,the novel hydrogel features high ionic conductivity,high resistance to swelling,and extraordinary anti-freezing property,holding great promise for applications in different practical scenarios,particularly in aqueous or cold environments.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(2018ZX10301402)International Cooperation and Exchange of the National Natural Science Foundation of China(51820105004)+3 种基金Science and Technology Program of Guangzhou(2019050001)National Natural Science Foundation of China(51973243,11874021 and 61675072)China Postdoctoral Science Foundation(2019M663246)Guangdong Innovative and Entrepreneurial Re-search Team Program(2013S086 , 2016ZT06S029).
文摘Effective cancer treatment puts high demands for cancer theranostics.For cancer diagnostics,optical coherence tomography(OCT)technology(including photothermal optical coherence tomography(PT-OCT))has been widely investigated since it induces changes in optical phase transitions in tissue through environmental changes(such as temperature change for PT-OCT).In this report,redox responsive nanoparticle encapsulating black phosphorus quantum dots was developed as a robust PT-OCT agent.Briefly,black phosphorus quantum dots(BPQDs)are incorporated into cysteine-based poly-(disulfide amide)(Cys-PDSA)to form stable and biodegradable nanoagent.The excellent photothermal feature allows BPQD/Cys-PDSA nanoparticles(NPs)as a novel contrast agent for high-resolution PT-OCT bioimaging.The Cys-PDSA can rapidly respond to glutathione and effectively release BPQDs and drugs in vitro and in vivo.And the obtained NPs exhibit excellent near-infrared(NIR)photothermal transduction efficiency and drug delivery capacity that can serve as novel therapeutic platform,with very low chemo drug dosage and side effects.Both of the polymer and BPQD are degradable,indicating this platform is a rare PT-OCT agent that is completely biodegradable.Overall,our research highlights a biodegradable and biocompatible black phosphorus-based nanoagent for both cancer diagnosis and therapy.
基金the financial support from the National Natural Science Foundation of China(21772109 and 21971140)the Beijing Natural Science Foundation(M21011)the Tsinghua-Peking University Center for Life Sciences(No.61020100120).
文摘The dyotropic rearrangement of β-lactones is a neglected treasure in the family of multi-bond reactions and pericyclic reactions.Despite its appealing synthetic potential,the complicated migration selectivity greatly limits its widespread application.In this work,we report the first systematic and comprehensive computational study on the dyotropic rearrangements of β-lactones.The use of the double-hybrid functional ensures the accuracy of results.On the basis of the present study and our previous work,five methods to control the reaction selectivity of dyotropic rearrangements of β-lactones have been summarized,providing valuable references for synthetic chemists to design and develop brand-new type dyotropic reactions.