Thermosets based on direct curing of multifunctional monomers offer processing flexibility that thermoplastics cannot provide.However,this type of thermoset is typically amorphous since it is difficult to meet the str...Thermosets based on direct curing of multifunctional monomers offer processing flexibility that thermoplastics cannot provide.However,this type of thermoset is typically amorphous since it is difficult to meet the stringent requirement of long-range molecular regularity for crystallization.However,we report here a crystallizable poly(thiourethane)thermoset synthesized directly from the curing of low-viscosity liquid precursors that does not employ any solvent.Its crystalline nature results in superior toughness,comparable to commercial high-density polyethylene,in sharp contrast to the brittleness of the typical,rigid,glassy thermoset materials.Beyond that,the network polymer exhibits shape-memory behavior in which the crystalline transition is utilized for temporary shape fixing/recovery whereas the dynamic thiourethane bonds can be activated for bond exchange as a mechanism for complex shape manipulation.Materials with these combined features represent attractive options for demanding engineering applications due to their high performance and multifunctinality.展开更多
The interface properties in two-dimensional(2D)layered materials and their van der Waals(vdW)homo-/heterostructures are of importance in both uncovering novel physical phenomena and optimizing device performance.Despi...The interface properties in two-dimensional(2D)layered materials and their van der Waals(vdW)homo-/heterostructures are of importance in both uncovering novel physical phenomena and optimizing device performance.Despite considerable research interest and enthusiasm direct toward the interlayer coupling in 2D homo-and heterostructures,there is limited research on the coupling at the 2D layered material-substrate interface.This limitation is due to the challenges in achieving direct detection.Currently,the coupling mechanisms at the 2D layered material-substrate interface is ambiguous,which needs greater attention.In this study,we have systematically investigated the interface coupling between monolayer WS_(2)and its supported substrates using high-temperature and high-vacuum in-situ Raman spectroscopy through monitoring the low-frequency Raman mode of monolayer WS_(2).Our findings reveal that both interfacial spacing and strain can significantly affect the coupling strength between the monolayer WS_(2)and the supported substrate.More notably,we found that the strategic introduction of appropriate interfacial strain can effectively enhance the interface coupling.Consequently,we have succeeded in achieving effective regulation of the sample-substrate coupling via a convenient way of controlling the cooling process during annealing.Our findings contribute to a deeper understanding of the coupling correlation between 2D layered materials and substrates,which is of great significance for the design and optimization of high-performance devices based on 2D layered semiconductors.展开更多
SARS-CoV-2,the causative agent for COVID-19,infect human mainly via respiratory tract,which is heavily inhabited by local microbiota.However,the interaction between SARS-CoV-2 and nasopharyngeal microbiota,and the ass...SARS-CoV-2,the causative agent for COVID-19,infect human mainly via respiratory tract,which is heavily inhabited by local microbiota.However,the interaction between SARS-CoV-2 and nasopharyngeal microbiota,and the association with metabolome has not been well characterized.Here,metabolomic analysis of blood,urine,and nasopharyngeal swabs from a group of COVID-19 and non-COVID-19 patients,and metagenomic analysis of pharyngeal samples were used to identify the key features of COVID-19.Results showed lactic acid,L-proline,and chlorogenic acid methyl ester(CME)were significantly reduced in the sera of COVID-19 patients compared with non-COVID-19 ones.Nasopharyngeal commensal bacteria including Gemella morbillorum,Gemella haemolysans and Leptotrichia hofstadii were notably depleted in the pharynges of COVID-19 patients,while Prevotella histicola,Streptococcus sanguinis,and Veillonella dispar were relatively increased.The abundance of G.haemolysans and L.hofstadii were significantly positively associated with serum CME,which might be an anti-SARS-CoV-2 bacterial metabolite.This study provides important information to explore the linkage between nasopharyngeal microbiota and disease susceptibility.The findings were based on a very limited number of patients enrolled in this study;a larger size of cohort will be appreciated for further investigation.展开更多
The state-of-the-art triboelectric nanogenerators(TENGs)are constructed with synthetic polymers,curtailing their application prospects and relevance in sustainable technologies.The economically viable transformation a...The state-of-the-art triboelectric nanogenerators(TENGs)are constructed with synthetic polymers,curtailing their application prospects and relevance in sustainable technologies.The economically viable transformation and engineering of naturally abundant materials into efficient TENGs for mechanical energy harvesting is meaningful not only for fundamental scientific exploration,but also for addressing societal needs.Being an abundant natural biopolymer,chitosan enables exciting opportunity for low-cost,biodegradable TENG applications.However,the electrical outputs of chitosan-based TENGs are low compared with the devices built with synthetic polymers.Here,we explore the facile molecular surface engineering in chitosan to significantly boost the performance of chitosan-based TENG for enabling the practical applications,for example,self-powered car speed sensor.The molecular surface engineering offers a potentially promising scheme for designing and implementing high-performance biopolymer-based TENGs for selfpowered nanosystems in sustainable technologies.We further explore for the first time the feasibility of data mining approaches to analyze and learn the acquired triboelectric signals from the car speed sensors and predict the relationship between the triboelectric signals and car speed values.展开更多
基金supported by the National Natural Science Foundation of China(grant nos.52322307,52033009,22275162,and 52003232).
文摘Thermosets based on direct curing of multifunctional monomers offer processing flexibility that thermoplastics cannot provide.However,this type of thermoset is typically amorphous since it is difficult to meet the stringent requirement of long-range molecular regularity for crystallization.However,we report here a crystallizable poly(thiourethane)thermoset synthesized directly from the curing of low-viscosity liquid precursors that does not employ any solvent.Its crystalline nature results in superior toughness,comparable to commercial high-density polyethylene,in sharp contrast to the brittleness of the typical,rigid,glassy thermoset materials.Beyond that,the network polymer exhibits shape-memory behavior in which the crystalline transition is utilized for temporary shape fixing/recovery whereas the dynamic thiourethane bonds can be activated for bond exchange as a mechanism for complex shape manipulation.Materials with these combined features represent attractive options for demanding engineering applications due to their high performance and multifunctinality.
基金supported by the National Key R&D Program of China(2018YFA0703700)the National Natural Science Foundation of China(62374037)+1 种基金Shanghai Municipal Natural Science Foundation(20ZR1403200)the National Young 1000 Talent Plan of China。
文摘The interface properties in two-dimensional(2D)layered materials and their van der Waals(vdW)homo-/heterostructures are of importance in both uncovering novel physical phenomena and optimizing device performance.Despite considerable research interest and enthusiasm direct toward the interlayer coupling in 2D homo-and heterostructures,there is limited research on the coupling at the 2D layered material-substrate interface.This limitation is due to the challenges in achieving direct detection.Currently,the coupling mechanisms at the 2D layered material-substrate interface is ambiguous,which needs greater attention.In this study,we have systematically investigated the interface coupling between monolayer WS_(2)and its supported substrates using high-temperature and high-vacuum in-situ Raman spectroscopy through monitoring the low-frequency Raman mode of monolayer WS_(2).Our findings reveal that both interfacial spacing and strain can significantly affect the coupling strength between the monolayer WS_(2)and the supported substrate.More notably,we found that the strategic introduction of appropriate interfacial strain can effectively enhance the interface coupling.Consequently,we have succeeded in achieving effective regulation of the sample-substrate coupling via a convenient way of controlling the cooling process during annealing.Our findings contribute to a deeper understanding of the coupling correlation between 2D layered materials and substrates,which is of great significance for the design and optimization of high-performance devices based on 2D layered semiconductors.
基金supported by National Science and Technology Major Project(2018ZX10302204)Shenzhen Science and Technology Program(Grant No.KQTD20200820145822023)+3 种基金Emergency special program for 2019-nCov of Guangdong province science and technology project(2020B111105001)Guangzhou science and technology project(202008040003)Clinical Research Foundation of the third Affiliated Hospital of Sun Yat-sen University(YHJH201904)National Natural Science Foundation of China(Grant No.31900056).
文摘SARS-CoV-2,the causative agent for COVID-19,infect human mainly via respiratory tract,which is heavily inhabited by local microbiota.However,the interaction between SARS-CoV-2 and nasopharyngeal microbiota,and the association with metabolome has not been well characterized.Here,metabolomic analysis of blood,urine,and nasopharyngeal swabs from a group of COVID-19 and non-COVID-19 patients,and metagenomic analysis of pharyngeal samples were used to identify the key features of COVID-19.Results showed lactic acid,L-proline,and chlorogenic acid methyl ester(CME)were significantly reduced in the sera of COVID-19 patients compared with non-COVID-19 ones.Nasopharyngeal commensal bacteria including Gemella morbillorum,Gemella haemolysans and Leptotrichia hofstadii were notably depleted in the pharynges of COVID-19 patients,while Prevotella histicola,Streptococcus sanguinis,and Veillonella dispar were relatively increased.The abundance of G.haemolysans and L.hofstadii were significantly positively associated with serum CME,which might be an anti-SARS-CoV-2 bacterial metabolite.This study provides important information to explore the linkage between nasopharyngeal microbiota and disease susceptibility.The findings were based on a very limited number of patients enrolled in this study;a larger size of cohort will be appreciated for further investigation.
基金W.Z.W.acknowledge the College of Engineering and School of Industrial Engineering at Purdue University for the startup support and the Ravi and Eleanor Talwar Rising Star Assistant Professorship.The support provided by the China Scholarship Council(CSC)during a visit of Chenxiang Ma to Purdue University is acknowledged.
文摘The state-of-the-art triboelectric nanogenerators(TENGs)are constructed with synthetic polymers,curtailing their application prospects and relevance in sustainable technologies.The economically viable transformation and engineering of naturally abundant materials into efficient TENGs for mechanical energy harvesting is meaningful not only for fundamental scientific exploration,but also for addressing societal needs.Being an abundant natural biopolymer,chitosan enables exciting opportunity for low-cost,biodegradable TENG applications.However,the electrical outputs of chitosan-based TENGs are low compared with the devices built with synthetic polymers.Here,we explore the facile molecular surface engineering in chitosan to significantly boost the performance of chitosan-based TENG for enabling the practical applications,for example,self-powered car speed sensor.The molecular surface engineering offers a potentially promising scheme for designing and implementing high-performance biopolymer-based TENGs for selfpowered nanosystems in sustainable technologies.We further explore for the first time the feasibility of data mining approaches to analyze and learn the acquired triboelectric signals from the car speed sensors and predict the relationship between the triboelectric signals and car speed values.
