We report an efficient and economical way for mass production of large-scale graphene films with high quality and uniformity.By using the designed scrolled copper-graphite structure,a continuous graphene film with typ...We report an efficient and economical way for mass production of large-scale graphene films with high quality and uniformity.By using the designed scrolled copper-graphite structure,a continuous graphene film with typical area of 200×39 cm^2 could be obtained in 15 min,and the production rate of the graphene film and space utilization rate of the CVD reactor can reach 520 cm 2⋅min−1 and 0.38 cm−1⋅min−1,respectively.Our method provides a guidance for the industrial production of graphene films,and may also accelerate its large-scale applications.展开更多
Probability-based diagnostic imaging(PDI)is one of the most well-known damage identification methods using guided waves.It is usually applied to diagnose damage in plates.The previous studies were dependent on the cer...Probability-based diagnostic imaging(PDI)is one of the most well-known damage identification methods using guided waves.It is usually applied to diagnose damage in plates.The previous studies were dependent on the certain damage index(DI)which is always calculated from the guided wave signals.In conventional methods,DI is simply defined by comparing the real-time data with the baseline data as reference.However,the baseline signal is easily affected by varying environmental conditions of structures.In this paper,a reference-free diagnostic imaging method is developed to avoid the influence of environmental factors,such as temperature and load conditions.The DI is defined based on the mode conversion of multi-mode guided waves with realtime signals without baseline signals.To improve the accuracy of diagnosis,two terms are included in the reference-free DI.One is called energy DI,which is defined based on the feature of signal energy.The other is called correlation DI and is defined based on the correlation coefficient.Then the PDI algorithm can be carried out instantaneously according to the reference-free DI.The real-time signals which are used to calculate DI are collected by the piezoelectric lead zirconate titanate(PZT)transducers placed on both sides of a plate.The numerical simulations by the finite element(FE)method on aluminum plates with PZT arrays are performed to validate the effectiveness of the reference-free damage diagnostic imaging.The approach is validated by two different arrays:a circle network and a square network.The results of diagnostic imaging are demonstrated and discussed in this paper.Furthermore,the advantage of reference-free DI is investigated by comparing the accuracy of defined reference-free DI and energy DI.展开更多
Improving the emission performance of colloidal quantum dots(QDs)is of paramount importance for their applications on light-emitting diodes(LEDs),displays and lasers.A highly promising approach is to tune the carrier ...Improving the emission performance of colloidal quantum dots(QDs)is of paramount importance for their applications on light-emitting diodes(LEDs),displays and lasers.A highly promising approach is to tune the carrier recombination channels and lifetime by exploiting the energy transfer process.However,to achieve this precise emission optimization,quantitative modulation on energy transfer efficiency is highly desirable but still challenging.Here,we demonstrate a convenient approach to realize tunable energy transfer efficiency by forming QDs mixture with controllable donor/acceptor(D/A)ratio.With the mixing ratio ranging from 16/1 to 1/16,the energy transfer efficiency could be effectively tuned from near zero to~70%.For the high mixing ratio of 16/1,acceptors obtain adequate energy supplied by closely surrounding donors,leading to~2.4-fold PL enhancement.While for the low mixing ratio,the ultrafast and efficient energy extraction process directly suppresses the multi-exciton and Auger recombination in the donor,bringing about a higher threshold.The facile modulation of emission performance by controllably designed mixing ratio and quantitatively tunable energy transfer efficiency will facilitate QD-based optoelectronic and photovoltaic applications.展开更多
Airborne particulate matter(PM)has been the leading contributor to air pollution,posing a substantial risk to human health,and effective filtration technologies are required.Two-dimensional(2D)materials,such as graphe...Airborne particulate matter(PM)has been the leading contributor to air pollution,posing a substantial risk to human health,and effective filtration technologies are required.Two-dimensional(2D)materials,such as graphene,graphitic carbon nitride(g-C3N4),molybdenum disulfide(MoS2),and MXenes have emerged in recent years for PM filtration due to their exception-ally large specific surface area and unique electrical properties.Here,the most extensively used 2D materials for PM filtration followed by a summary of their fabrication methods and corresponding morphologies were introduced.Among them,the coating is the most cost-effective technique for achieving large-scale and quick fabrication.Electrospinning can effectively enhance filtration efficiency and reduce pressure drop by upgrading electrostatic force and lowering the fiber diameter.The initial and long-term performance of 2D-material-based filters was summarized.Among all 2D materials,GO is the most studied and shows the best performance by upgrading the dipole–dipole and electrostatic interaction between filters and PM.Future study is expected to explore various 2D materials beyond GO,to evaluate filtration efficiency for submicron PM at m/s level air velocity,and to extend the service life for potential applications.展开更多
Depending on the production process,copper(Cu)foils can be classified into two types,i.e.,rolled copper(r-Cu)foils and electrolytic copper(e-Cu)foils.Owing to their high electrical conductivity and ductility at low co...Depending on the production process,copper(Cu)foils can be classified into two types,i.e.,rolled copper(r-Cu)foils and electrolytic copper(e-Cu)foils.Owing to their high electrical conductivity and ductility at low cost,e-Cu foils are employed extensively in modern industries and account for more than 98%of the Cu foil market share.However,industrial e-Cu foils have never been single-crystallized due to their high density of grain boundaries,various grain orientations and vast impurities originating from the electrochemical deposition process.Here,we report a methodology of transforming industrial e-Cu foils into single crystals by facet copy from a single-crystal template.Different facets of both low and high indices are successfully produced,and the thickness of the single crystal can reach 500μm.Crystallographic characterizations directly recognized the single-crystal copy process,confirming the complete assimilation impact from the template.The obtained single-crystal e-Cu foils exhibit remarkably improved ductility(elongation-to-fracture of 105%vs.25%),fatigue performance(the average numbers of cycles to failure of 1600 vs.200)and electrical property(electrical conductivity of 102.6%of the international annealed copper standard(IACS)vs.98.5%)than original ones.This work opens up a new avenue for the preparation of single-crystal e-Cu foils and may expand their applications in high-speed,flexible,and wearable devices.展开更多
This study aimed to characterize the chemical composition of a new sulfated polysaccharide from the red alga Gracilaria chouae and evaluate its activation effects on RAW264.7 macrophages.It showed that the obtained G....This study aimed to characterize the chemical composition of a new sulfated polysaccharide from the red alga Gracilaria chouae and evaluate its activation effects on RAW264.7 macrophages.It showed that the obtained G.chouae polysaccharide(GCP-3A)was a sulfated acidic polysaccharide with a molecular weight of 11.87 kDa.展开更多
Atomic-layered hexagonal boron nitride(hBN)is expected to be the best two-dimensional(2D)anti-oxidation layer on metals for its incomparable impermeability,insulativity,and stability,as well as the progressive bottom-...Atomic-layered hexagonal boron nitride(hBN)is expected to be the best two-dimensional(2D)anti-oxidation layer on metals for its incomparable impermeability,insulativity,and stability,as well as the progressive bottom-up growth techniques to ensure fast coating on metal surface in large area.However,its real anti-oxidation ability in practice is found to be unsatisfactory and nonuniform,and the main obstacle to achieving ideal anti-oxidation performance lies in unclear anti-oxidation behavior at special interface between 2D hBN and three-dimensional(3D)metals.Herein,system of monolayer hBN grown on copper(Cu)foils with various lattice orientations was grown to investigate the anti-oxidation behavior of different interlayer configurations.By using structural characterizations together with analysis of topography,we surprisingly found that stronger interlayer coupling led to worse anti-oxidation performance owing to fast diffusion of O2 through higher hBN corrugations generated at the commensurate hBN/Cu(111)configuration.In view of this,we developed the approach of cyclic reannealing that can effectively flatten corrugations and steps,and therefore improve the anti-oxidation performance to a great extent.This work provides a more indepth understanding of anti-oxidation behavior of 2D materials grown on 3D metals,and a practical method to pave the way for its large-scale applications in future.展开更多
基金Supported by the Beijing Natural Science Foundation(Grant No.JQ19004)the Key R&D Program of Guangdong Province(Grant Nos.2019B010931001,2020B010189001,2018B010109009 and 2018B030327001)+9 种基金Bureau of Industry and Information Technology of Shenzhen(Graphene platform 201901161512)the National Natural Science Foundation of China(Grant Nos.51991340,51991342 and 51522201)the National Key R&D Program of China(Grant Nos.2016YFA0300903 and 2016YFA0300804)the Beijing Excellent Talents Training Support(Grant No.2017000026833ZK11)the Beijing Municipal Science&Technology Commission(Grant No.Z191100007219005)the Beijing Graphene Innovation Program(Z181100004818003)the Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06D348)the Science,Technology and Innovation Commission of Shenzhen Municipality(Grant No.KYTDPT20181011104202253)the National Postdoctoral Program for Innovative Talents(Grant No.BX20190016)China Postdoctoral Science Foundation(Grant Nos.2019M660280 and 2019M660281).
文摘We report an efficient and economical way for mass production of large-scale graphene films with high quality and uniformity.By using the designed scrolled copper-graphite structure,a continuous graphene film with typical area of 200×39 cm^2 could be obtained in 15 min,and the production rate of the graphene film and space utilization rate of the CVD reactor can reach 520 cm 2⋅min−1 and 0.38 cm−1⋅min−1,respectively.Our method provides a guidance for the industrial production of graphene films,and may also accelerate its large-scale applications.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2016YFF0203002)the National Natural Science Foundation of China(Grant No.11702051)+1 种基金China Post-doctoral Science Foundation(Grant No.2017M610176)the Fundamental Research Funds for the Central Universities(DUT16ZD214).
文摘Probability-based diagnostic imaging(PDI)is one of the most well-known damage identification methods using guided waves.It is usually applied to diagnose damage in plates.The previous studies were dependent on the certain damage index(DI)which is always calculated from the guided wave signals.In conventional methods,DI is simply defined by comparing the real-time data with the baseline data as reference.However,the baseline signal is easily affected by varying environmental conditions of structures.In this paper,a reference-free diagnostic imaging method is developed to avoid the influence of environmental factors,such as temperature and load conditions.The DI is defined based on the mode conversion of multi-mode guided waves with realtime signals without baseline signals.To improve the accuracy of diagnosis,two terms are included in the reference-free DI.One is called energy DI,which is defined based on the feature of signal energy.The other is called correlation DI and is defined based on the correlation coefficient.Then the PDI algorithm can be carried out instantaneously according to the reference-free DI.The real-time signals which are used to calculate DI are collected by the piezoelectric lead zirconate titanate(PZT)transducers placed on both sides of a plate.The numerical simulations by the finite element(FE)method on aluminum plates with PZT arrays are performed to validate the effectiveness of the reference-free damage diagnostic imaging.The approach is validated by two different arrays:a circle network and a square network.The results of diagnostic imaging are demonstrated and discussed in this paper.Furthermore,the advantage of reference-free DI is investigated by comparing the accuracy of defined reference-free DI and energy DI.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52025023,51991342,52021006,11888101,and 61922028)the Key R&D Program of Guangdong Province,China(Grant Nos.2020B010189001,2019B010931001,and 2018B030327001)+3 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB33000000)Beijing Natural Science Foundation,China(Grant No.JQ19004)the Pearl River Talent Recruitment Program of Guangdong Province,China(Grant No.2019ZT08C321)China Postdoctoral Science Foundation(Grant No.2021T140022)。
文摘Improving the emission performance of colloidal quantum dots(QDs)is of paramount importance for their applications on light-emitting diodes(LEDs),displays and lasers.A highly promising approach is to tune the carrier recombination channels and lifetime by exploiting the energy transfer process.However,to achieve this precise emission optimization,quantitative modulation on energy transfer efficiency is highly desirable but still challenging.Here,we demonstrate a convenient approach to realize tunable energy transfer efficiency by forming QDs mixture with controllable donor/acceptor(D/A)ratio.With the mixing ratio ranging from 16/1 to 1/16,the energy transfer efficiency could be effectively tuned from near zero to~70%.For the high mixing ratio of 16/1,acceptors obtain adequate energy supplied by closely surrounding donors,leading to~2.4-fold PL enhancement.While for the low mixing ratio,the ultrafast and efficient energy extraction process directly suppresses the multi-exciton and Auger recombination in the donor,bringing about a higher threshold.The facile modulation of emission performance by controllably designed mixing ratio and quantitatively tunable energy transfer efficiency will facilitate QD-based optoelectronic and photovoltaic applications.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030002)the Key R&D Program of Guangdong Province(2020B010189001,2019B010931001 and 2018B030327001)+1 种基金the National Natural Science Foundation of China(52025023,51991342,52021006,92163206,11888101,51972069)the Science and Technology Projects in Guangzhou(202102010470).
文摘Airborne particulate matter(PM)has been the leading contributor to air pollution,posing a substantial risk to human health,and effective filtration technologies are required.Two-dimensional(2D)materials,such as graphene,graphitic carbon nitride(g-C3N4),molybdenum disulfide(MoS2),and MXenes have emerged in recent years for PM filtration due to their exception-ally large specific surface area and unique electrical properties.Here,the most extensively used 2D materials for PM filtration followed by a summary of their fabrication methods and corresponding morphologies were introduced.Among them,the coating is the most cost-effective technique for achieving large-scale and quick fabrication.Electrospinning can effectively enhance filtration efficiency and reduce pressure drop by upgrading electrostatic force and lowering the fiber diameter.The initial and long-term performance of 2D-material-based filters was summarized.Among all 2D materials,GO is the most studied and shows the best performance by upgrading the dipole–dipole and electrostatic interaction between filters and PM.Future study is expected to explore various 2D materials beyond GO,to evaluate filtration efficiency for submicron PM at m/s level air velocity,and to extend the service life for potential applications.
基金financially supported by Guangdong Major Project of Basic and Applied Basic Research(No.2021B0301030002)the National Natural Science Foundation of China(No.52025023)the Key R&D Program of Guangdong Province(No.2020B010189001).
文摘Depending on the production process,copper(Cu)foils can be classified into two types,i.e.,rolled copper(r-Cu)foils and electrolytic copper(e-Cu)foils.Owing to their high electrical conductivity and ductility at low cost,e-Cu foils are employed extensively in modern industries and account for more than 98%of the Cu foil market share.However,industrial e-Cu foils have never been single-crystallized due to their high density of grain boundaries,various grain orientations and vast impurities originating from the electrochemical deposition process.Here,we report a methodology of transforming industrial e-Cu foils into single crystals by facet copy from a single-crystal template.Different facets of both low and high indices are successfully produced,and the thickness of the single crystal can reach 500μm.Crystallographic characterizations directly recognized the single-crystal copy process,confirming the complete assimilation impact from the template.The obtained single-crystal e-Cu foils exhibit remarkably improved ductility(elongation-to-fracture of 105%vs.25%),fatigue performance(the average numbers of cycles to failure of 1600 vs.200)and electrical property(electrical conductivity of 102.6%of the international annealed copper standard(IACS)vs.98.5%)than original ones.This work opens up a new avenue for the preparation of single-crystal e-Cu foils and may expand their applications in high-speed,flexible,and wearable devices.
基金This work was supported by the National Natural Science Foundation of China(No.81572989)the International Academic Cooperation of Science and Technology Committee of Shanghai,China(No.18430721100).
文摘This study aimed to characterize the chemical composition of a new sulfated polysaccharide from the red alga Gracilaria chouae and evaluate its activation effects on RAW264.7 macrophages.It showed that the obtained G.chouae polysaccharide(GCP-3A)was a sulfated acidic polysaccharide with a molecular weight of 11.87 kDa.
基金the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030002)the National Natural Science Foundation of China(Nos.52025023,51991342,52021006,11888101,12025203,and 12104493)+7 种基金the Key Research&Development Program of Guangdong Province(Nos.2020B010189001,2019B010931001,and 2018B030327001)the Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB33000000 and XDB33030200)Beijing Natural Science Foundation(No.JQ19004)Natural Science Foundation of Jiangsu Province(No.BK20170426)the Initiative Program of State Key Laboratory of Tribology(No.SKLT2019B02)the National Key R&D Program of China(No.2018YFA0703700)Program from Chinese Academy of Sciences(No.E0K5231B11)the Pearl River Talent Recruitment Program of Guangdong Province(No.2019ZT08C321)。
文摘Atomic-layered hexagonal boron nitride(hBN)is expected to be the best two-dimensional(2D)anti-oxidation layer on metals for its incomparable impermeability,insulativity,and stability,as well as the progressive bottom-up growth techniques to ensure fast coating on metal surface in large area.However,its real anti-oxidation ability in practice is found to be unsatisfactory and nonuniform,and the main obstacle to achieving ideal anti-oxidation performance lies in unclear anti-oxidation behavior at special interface between 2D hBN and three-dimensional(3D)metals.Herein,system of monolayer hBN grown on copper(Cu)foils with various lattice orientations was grown to investigate the anti-oxidation behavior of different interlayer configurations.By using structural characterizations together with analysis of topography,we surprisingly found that stronger interlayer coupling led to worse anti-oxidation performance owing to fast diffusion of O2 through higher hBN corrugations generated at the commensurate hBN/Cu(111)configuration.In view of this,we developed the approach of cyclic reannealing that can effectively flatten corrugations and steps,and therefore improve the anti-oxidation performance to a great extent.This work provides a more indepth understanding of anti-oxidation behavior of 2D materials grown on 3D metals,and a practical method to pave the way for its large-scale applications in future.
