Defects in cast-in-situ piles have an adverse impact on load transfer at the pile‒soil interface and pile bearing capacity. In recent years, thermal integrity profiling (TIP) has been developed to measure temperature ...Defects in cast-in-situ piles have an adverse impact on load transfer at the pile‒soil interface and pile bearing capacity. In recent years, thermal integrity profiling (TIP) has been developed to measure temperature profiles of cast-in-situ piles, enabling the detection of structural defects or anomalies at the early stage of construction. However, using this integrity testing method to evaluate potential defects in cast-in-situ piles requires a comprehensive understanding of the mechanism of hydration heat transfer from piles to surrounding soils. In this study, small-scale model tests were conducted in laboratory to investigate the performance of TIP in detecting pile integrity. Fiber-optic distributed temperature sensing (DTS) technology was used to monitor detailed temperature variations along model piles in sand. Additionally, sensors were installed in sand to measure water content and matric suction. An interpretation method against available DTS-based thermal profiles was proposed to reveal the potential defective regions. It shows that the temperature difference between normal and defective piles is more obvious in wet sand. In addition, there is a critical zone of water migration in sand due to the water absorption behavior of cement and temperature transfer-induced water migration in the early-age concrete setting. These findings could provide important insight into the improvement of the TIP testing method for field applications.展开更多
By modifying friction to the desired level,the application of friction modifiers(FMs)has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion c...By modifying friction to the desired level,the application of friction modifiers(FMs)has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion conditions and mitigating wheel/rail interface deterioration,energy consumption,vibration and noise.Understanding the effectiveness of FMs in wheel–rail dynamic interactions is crucial to their proper applications in practice,which has,however,not been well explained.This study experimentally investigates the effects of two types of top-of-rail FM,i.e.FM-A and FM-B,and their application dosages on wheel–rail dynamic interactions with a range of angles of attack(AoAs)using an innovative well-controlled V-track test rig.The tested FMs have been used to provide intermediate friction for wear and noise reduction.The effectiveness of the FMs is assessed in terms of the wheel–rail adhesion characteristics and friction rolling induced axle box acceleration(ABA).This study provides the following new insights into the study of FM:the applications of the tested FMs can both reduce the wheel–rail adhesion level and change the negative friction characteristic to positive;stick–slip can be generated in the V-Track and eliminated by FM-A but intensified by FM-B,depending on the dosage of the FMs applied;the negative friction characteristic is not a must for stick–slip;the increase in ABA with AoA is insignificant until stick–slip occurs and the ABA can thus be influenced by the applications of FM.展开更多
H9N2 subtype avian influenza virus(AIV)is an influenza A virus that is widely spread throughout Asia,where it jeopardizes the poultry industry and provides genetic material for emerging human pathogens.To better under...H9N2 subtype avian influenza virus(AIV)is an influenza A virus that is widely spread throughout Asia,where it jeopardizes the poultry industry and provides genetic material for emerging human pathogens.To better understand the epidemicity and genetics of H9 subtype AIVs,we conducted active surveillance in live poultry markets(LPMs)in Hubei Province from 2013 to 2017.A total of 4798 samples were collected from apparent healthy poultry and environment.Realtime RT-PCR revealed that the positivity rate of influenza A was 26.6%(1275/4798),of which the H9 subtype accounted for 50.3%(641/1275)of the positive samples.Of the 132 H9N2 viral strains isolated,48 representative strains were subjected to evolutionary analysis and genotyping.Phylogenetic analysis revealed that all H9N2 viral genes had 91.1%–100%nucleotide homology,clustered with genotype 57,and had high homology with human H9N2 viruses isolated from2013 to 2017 in China.Using a nucleotide divergence cutoff of 95%,we identified ten distinct H9N2 genotypes that continued to change over time.Molecular analysis demonstrated that six H9N2 isolates had additional potential glycosylation sites at position 218 in the hemagglutinin protein,and all isolates had I155 T and Q226 L mutations.Moreover,44 strains had A558 V mutations in the PB2 protein and four had E627 V mutations,along with H9N2 human infection strains A/Beijing/1/2016 and A/Beijing/1/2017.These results emphasize that the H9N2 influenza virus in Hubei continues to mutate and undergo mammalian adaptation changes,indicating the necessity of strengthening the surveillance of the AIV H9N2 subtype in LPMs.展开更多
Long term ground movements above a tunnel may continue to increase with time after tunnelling in clayey soils as the tunnellinginduced excess pore water pressures dissipate,whilst the changing earth pressure acting on...Long term ground movements above a tunnel may continue to increase with time after tunnelling in clayey soils as the tunnellinginduced excess pore water pressures dissipate,whilst the changing earth pressure acting on the tunnel leads to further tunnel deformation during consolidation.Furthermore the tunnel itself introduces new drainage conditions;that is,depending on the drainage condition of the tunnel lining,the effective stresses around the tunnel change with time,inducing further soil consolidation.A seepage rate from low permeability clayey soil is often very small and the groundwater seeping into the tunnel can evaporate quickly.Although a tunnel may look impermeable because the surface looks dry,it is possible that the tunnel drainage conditions are actually permeable.This paper summarises the investigation of soil-tunnel consolidation interaction,particularly focusing on ground surface movements and tunnel lining deformation in the interest of engineering concerns.Analysis results show that tunnel lining permittivity relative to the permeability of the surrounding ground plays an important role on both long-term ground movements as well as tunnel lining behaviour.The findings published in literature are reviewed step by step starting from a single tunnel,twin tunnels to complex cross passage structures.The mechanisms of tunnelling-induced soil consolidation for these structures are identified and,where applicable,possible engineering methodologies to assess the magnitude of long-term ground surface settlements and tunnel lining loads are proposed.展开更多
Hydrogels are three-dimensional(3D)crosslinked hydrophilic polymer networks that have garnered tremendous interests in many fields,including water treatment,energy storage,and regenerative medicine.However,conventiona...Hydrogels are three-dimensional(3D)crosslinked hydrophilic polymer networks that have garnered tremendous interests in many fields,including water treatment,energy storage,and regenerative medicine.However,conventional synthetic polymer hydrogels have poor biocompatibility.In this context,polysaccharides,a class of renewable natural materials with biocompatible and biodegradable properties,have been utilized as building blocks to yield polysaccharide-based hydrogels through physical and/or chemical crosslinking of polysaccharides via a variety of monomers or ions.These polysaccharide-derived hydrogels exhibit peculiar physicochemical properties and excellent mechanical properties due to their unique structures and abundant functional groups.This review focuses on recent advances in synthesis and applications of polysaccharide-based hydrogels by capitalizing on a set of biocompatible and biodegradable polysaccharides(i.e.,cellulose,alginate,chitosan,and cyclodextrins[CDs]).First,we introduce the design and synthesis principles for crafting polysaccharide-based hydrogels.Second,polysaccharidebased hydrogels that are interconnected via various crosslinking strategies(e.g.,physical crosslinking,chemical crosslinking,and double networking)are summarized.In particular,the introduction of noncovalent and/or dynamic covalent interactions imparts polysaccharide-based hydrogels with a myriad of intriguing performances(e.g.,stimuli–response and self-recovery).Third,the diverse applications of polysaccharide-based hydrogels in self-healing,sensory,supercapacitor,battery,drug delivery,wound healing,tissues engineering,and bioimaging fields are discussed.Finally,the perspectives of polysaccharide-based hydrogels that promote their future design to enable new functions and applications are outlined.展开更多
基金The authors grate fully acknowledge the financial support provided by the National Natural Science Foundation of China(Grant Nos.42225702 and 42077235)the Open Research Project Program of the State Key Laboratory of Internet of Things for Smart City(University of Macao),China(Grant No.SKUoTSC(UM)-2021-2023/0RP/GA10/2022).
文摘Defects in cast-in-situ piles have an adverse impact on load transfer at the pile‒soil interface and pile bearing capacity. In recent years, thermal integrity profiling (TIP) has been developed to measure temperature profiles of cast-in-situ piles, enabling the detection of structural defects or anomalies at the early stage of construction. However, using this integrity testing method to evaluate potential defects in cast-in-situ piles requires a comprehensive understanding of the mechanism of hydration heat transfer from piles to surrounding soils. In this study, small-scale model tests were conducted in laboratory to investigate the performance of TIP in detecting pile integrity. Fiber-optic distributed temperature sensing (DTS) technology was used to monitor detailed temperature variations along model piles in sand. Additionally, sensors were installed in sand to measure water content and matric suction. An interpretation method against available DTS-based thermal profiles was proposed to reveal the potential defective regions. It shows that the temperature difference between normal and defective piles is more obvious in wet sand. In addition, there is a critical zone of water migration in sand due to the water absorption behavior of cement and temperature transfer-induced water migration in the early-age concrete setting. These findings could provide important insight into the improvement of the TIP testing method for field applications.
基金supported by European Union’s Horizon 2020 research and innovation programme in the project In2Track2 under Grant agreement No. 826255
文摘By modifying friction to the desired level,the application of friction modifiers(FMs)has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion conditions and mitigating wheel/rail interface deterioration,energy consumption,vibration and noise.Understanding the effectiveness of FMs in wheel–rail dynamic interactions is crucial to their proper applications in practice,which has,however,not been well explained.This study experimentally investigates the effects of two types of top-of-rail FM,i.e.FM-A and FM-B,and their application dosages on wheel–rail dynamic interactions with a range of angles of attack(AoAs)using an innovative well-controlled V-track test rig.The tested FMs have been used to provide intermediate friction for wear and noise reduction.The effectiveness of the FMs is assessed in terms of the wheel–rail adhesion characteristics and friction rolling induced axle box acceleration(ABA).This study provides the following new insights into the study of FM:the applications of the tested FMs can both reduce the wheel–rail adhesion level and change the negative friction characteristic to positive;stick–slip can be generated in the V-Track and eliminated by FM-A but intensified by FM-B,depending on the dosage of the FMs applied;the negative friction characteristic is not a must for stick–slip;the increase in ABA with AoA is insignificant until stick–slip occurs and the ABA can thus be influenced by the applications of FM.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFD0500800 to ZL)。
文摘H9N2 subtype avian influenza virus(AIV)is an influenza A virus that is widely spread throughout Asia,where it jeopardizes the poultry industry and provides genetic material for emerging human pathogens.To better understand the epidemicity and genetics of H9 subtype AIVs,we conducted active surveillance in live poultry markets(LPMs)in Hubei Province from 2013 to 2017.A total of 4798 samples were collected from apparent healthy poultry and environment.Realtime RT-PCR revealed that the positivity rate of influenza A was 26.6%(1275/4798),of which the H9 subtype accounted for 50.3%(641/1275)of the positive samples.Of the 132 H9N2 viral strains isolated,48 representative strains were subjected to evolutionary analysis and genotyping.Phylogenetic analysis revealed that all H9N2 viral genes had 91.1%–100%nucleotide homology,clustered with genotype 57,and had high homology with human H9N2 viruses isolated from2013 to 2017 in China.Using a nucleotide divergence cutoff of 95%,we identified ten distinct H9N2 genotypes that continued to change over time.Molecular analysis demonstrated that six H9N2 isolates had additional potential glycosylation sites at position 218 in the hemagglutinin protein,and all isolates had I155 T and Q226 L mutations.Moreover,44 strains had A558 V mutations in the PB2 protein and four had E627 V mutations,along with H9N2 human infection strains A/Beijing/1/2016 and A/Beijing/1/2017.These results emphasize that the H9N2 influenza virus in Hubei continues to mutate and undergo mammalian adaptation changes,indicating the necessity of strengthening the surveillance of the AIV H9N2 subtype in LPMs.
基金This work was supported by National Natural Science Foundation of China(No.51508403)by National Natural Science Foundation of China(No.51608539).
文摘Long term ground movements above a tunnel may continue to increase with time after tunnelling in clayey soils as the tunnellinginduced excess pore water pressures dissipate,whilst the changing earth pressure acting on the tunnel leads to further tunnel deformation during consolidation.Furthermore the tunnel itself introduces new drainage conditions;that is,depending on the drainage condition of the tunnel lining,the effective stresses around the tunnel change with time,inducing further soil consolidation.A seepage rate from low permeability clayey soil is often very small and the groundwater seeping into the tunnel can evaporate quickly.Although a tunnel may look impermeable because the surface looks dry,it is possible that the tunnel drainage conditions are actually permeable.This paper summarises the investigation of soil-tunnel consolidation interaction,particularly focusing on ground surface movements and tunnel lining deformation in the interest of engineering concerns.Analysis results show that tunnel lining permittivity relative to the permeability of the surrounding ground plays an important role on both long-term ground movements as well as tunnel lining behaviour.The findings published in literature are reviewed step by step starting from a single tunnel,twin tunnels to complex cross passage structures.The mechanisms of tunnelling-induced soil consolidation for these structures are identified and,where applicable,possible engineering methodologies to assess the magnitude of long-term ground surface settlements and tunnel lining loads are proposed.
基金supported by the Air Force Office of Scientific Research(FA9550-19-1-0317)the NSF(DMR 1903990,and Chemistry 1903957).
文摘Hydrogels are three-dimensional(3D)crosslinked hydrophilic polymer networks that have garnered tremendous interests in many fields,including water treatment,energy storage,and regenerative medicine.However,conventional synthetic polymer hydrogels have poor biocompatibility.In this context,polysaccharides,a class of renewable natural materials with biocompatible and biodegradable properties,have been utilized as building blocks to yield polysaccharide-based hydrogels through physical and/or chemical crosslinking of polysaccharides via a variety of monomers or ions.These polysaccharide-derived hydrogels exhibit peculiar physicochemical properties and excellent mechanical properties due to their unique structures and abundant functional groups.This review focuses on recent advances in synthesis and applications of polysaccharide-based hydrogels by capitalizing on a set of biocompatible and biodegradable polysaccharides(i.e.,cellulose,alginate,chitosan,and cyclodextrins[CDs]).First,we introduce the design and synthesis principles for crafting polysaccharide-based hydrogels.Second,polysaccharidebased hydrogels that are interconnected via various crosslinking strategies(e.g.,physical crosslinking,chemical crosslinking,and double networking)are summarized.In particular,the introduction of noncovalent and/or dynamic covalent interactions imparts polysaccharide-based hydrogels with a myriad of intriguing performances(e.g.,stimuli–response and self-recovery).Third,the diverse applications of polysaccharide-based hydrogels in self-healing,sensory,supercapacitor,battery,drug delivery,wound healing,tissues engineering,and bioimaging fields are discussed.Finally,the perspectives of polysaccharide-based hydrogels that promote their future design to enable new functions and applications are outlined.
