The hydrogenation of levulinic acid(LA)to c-valerolactone(GVL)by using water as solvent is a crucial process in the production of fine chemicals from biomass.An ultrathin carbon layer coating CoRu bimetallic catalyst ...The hydrogenation of levulinic acid(LA)to c-valerolactone(GVL)by using water as solvent is a crucial process in the production of fine chemicals from biomass.An ultrathin carbon layer coating CoRu bimetallic catalyst supported on silica(CoRu@C/SiO2)is prepared by using tannis-ligated cobalt-ruthenium complex on silica as precursors,and applied for catalyzed synthesis of GVL from LA.Because of the synergistic effect between cobalt and ruthenium,the addition of small amounts of Ru to Co catalysts can increase the catalytic activity in the aqueous hydrogenation of LA.The ultrathin carbon layer covered on the CoRu bimetallic catalyst can greatly reduce the leaching of active metals.The CoRu@C/SiO2 catalyst achieves high stability and is reused up to 5 runs without significant loss of performance in aqueous hydrogenation of levulinic acid.展开更多
Biochip is essentially a bio-microarray device that can perform hundreds or thousands of simultaneous biochemical reactions.[1, 2] It offers the researchers a new way for large-scale genomic, proteomic and functional ...Biochip is essentially a bio-microarray device that can perform hundreds or thousands of simultaneous biochemical reactions.[1, 2] It offers the researchers a new way for large-scale genomic, proteomic and functional genomic analyses. The biochips also enable people to quickly screen large numbers of biological analyses for many different purposes, from disease diagnosis to detection of bioterrorism chemical agents.[3]展开更多
Plague has caused the death of hundreds of millions of people throughout the human history.Today this disease is again re-emerging and hence is again becoming an increasing threat to human health in several parts of t...Plague has caused the death of hundreds of millions of people throughout the human history.Today this disease is again re-emerging and hence is again becoming an increasing threat to human health in several parts of the world.However,impacts of global climate variation(e.g.El Nino and Southern Oscillation[ENSO])and global warming on plagues are largely unknown.Using cross-spectral analysis and cross-wavelet analysis,we have analyzed the relationship between increase rate of human plague in China during 1871–2003 and the following climate factors(as measured by the Southern Oscillation Index[SOI],Sea Surface Temperature of east Pacific equator[SST]and air Temperature of the Northern Hemisphere[NHT]).We found in the frequency domain that increase rate of human plague was closely associated with SOI and SST.Cross-spectral analysis reveals that significant coherencies between increase rate of human plague and ENSO were found over short periods(2–3 years),medium periods(6–7 years)and long periods(11–12 years,30–40 years).Cross-wavelet analysis reveals that increase rate of human plague oscillates in phase with SOI,but in anti-phase with SST over periods of 2–4 years and approximately 8 years(6–10 years).These results indicate that ENSO-driven climate variation may be important for occurrences of human plague in China.However,there is a need for a further analysis of the underlying mechanism between human plague in China and ENSO.展开更多
Aims To explore whether the trade-off between seed and vegetative reproductive modes is flexible in environments with different amounts of available resources to maintain optimal behaviors.Methods A transition matrix ...Aims To explore whether the trade-off between seed and vegetative reproductive modes is flexible in environments with different amounts of available resources to maintain optimal behaviors.Methods A transition matrix model was established to determine the optimal trade-off between seed and vegetative reproduction in resources–variable habitats.Important Findings The model predicts that plants allocate more resources to seed reproduction when available resources are scarce.With increasing resources,more vegetative propagules are produced.However,if resources keep increasing to a harmful level,plants would switch to seeds again.展开更多
Stretchable strain sensor detects a wide range of strain variation and is therefore a key component in various applications.Unlike traditional ones made of elastomers doped with conductive components or fabricated wit...Stretchable strain sensor detects a wide range of strain variation and is therefore a key component in various applications.Unlike traditional ones made of elastomers doped with conductive components or fabricated with liquid conductors,ionically conductive hydrogel-based strain sensors remain conductive under large deformations and are biocompatible.However,dehydration is a challenging issue for the latter.Researchers have developed hydrogel-elastomer-based strain sensors where an elastomer matrix encapsulates a hydrogel circuit to prevent its dehydration.However,the reported multistep approaches are generally time-consuming.Our group recently reported a multimaterial 3D printing approach that enables fast fabrication of such sensors,yet requires a self-built digital-light-processing-based multimaterial 3D printer.Here,we report a simple projection lithography method to fabricate hydrogel-elastomer-based stretchable strain sensors within 5 minutes.This method only requires a UV projector/lamp with photomasks;the chemicals are commercially available;the protocols for preparing the polymer precursors are friendly to users without chemistry background.Moreover,the manufacturing flexibility allows users to readily pattern the sensor circuit and attach the sensor to a 3D printed soft pneumatic actuator to enable strain sensing on the latter.The proposed approach paves a simple and versatile way to fabricate hydrogel-elastomer-based stretchable strain sensors and flexible electronic devices.展开更多
Metal-semiconductor ohmic contacts are required to reduce the energy dissipation for two-dimensional (2D) electronic devices, and phase engineering of 2D transition-metal dichalcogenides (TMDCs) is a promising approac...Metal-semiconductor ohmic contacts are required to reduce the energy dissipation for two-dimensional (2D) electronic devices, and phase engineering of 2D transition-metal dichalcogenides (TMDCs) is a promising approach for building ohmic contacts. Here, 2D in-plane 1T′-2H MoTe2 homojunctions were prepared by direct epitaxy via vapor deposition. The interface properties of in-plane 1T′-2H MoTe2 homojunction were investigated in detail by combining experiments, calculations and theories. The ohmic contact properties of 1T′-2H MoTe2 homojunction were proved according to Kelvin force probe microscopy and density functional theory calculations. The charge carriers robust transport in in-plane 1T′-2H MoTe2 homojunction without Fermi-level pinning can be well described by Poisson equation and band alignment. These results indicate that phase engineering of 2D TMDCs is promising to construct ohmic contacts for device applications.展开更多
Evolutionary game theory has extensively investigated situations in which several gamesare competing against each other at the same time,but the model only assumes sym-metric interactions in homogeneous environments.N...Evolutionary game theory has extensively investigated situations in which several gamesare competing against each other at the same time,but the model only assumes sym-metric interactions in homogeneous environments.Now,the population is consideredin heterogeneous environments,individuals in the population occupy a different qualityof patches,and individual fitness depends not only on the interaction between individ-uals,but also on the quality of the environment.Here,by establishing a mathemati-cal framework,we analyze the natural selection between two strategies and two gamesin heterogeneous environments.Furthermore,we analyze the natural selection of Pris-oner's Dilemma and Hawk-Dove games theoretically to demonstrate the dynamics ofcooperators and defectors in their choice of environment and their respective games.Asexpected,the distribution of games and strategies changes with time.Based on differentinitial population compositions,we also discuss the invasion problem of games from dif-ferent perspectives.To one's surprise,we can find that good quality patches attract allindividuals;the long-term dynamics in invariant rich environments is the same as thedynamics of symmetric interactions in homogeneous environments.展开更多
A rapid and cost-effective method for fabricating mini lens arrays is proposed. The lenses are made of silicone oil droplets and filled inside a polydimethylsiloxane(PDMS) elastomer. The lens arrays of different initi...A rapid and cost-effective method for fabricating mini lens arrays is proposed. The lenses are made of silicone oil droplets and filled inside a polydimethylsiloxane(PDMS) elastomer. The lens arrays of different initial focal lengths and apertures can be fabricated by using the droplets of different volumes. Due to good elastic behavior of PDMS, the droplet lenses can be flexibly deformed, and the focal length and numerical aperture can be tuned by applying an external force on the PDMS elastomer. Furthermore, an apparatus for focal length tuning is designed and employed in the imaging system.展开更多
基金supported by the National Natural Science Foundation of China(21908197)Natural Science Foundation of Zhejiang Province(LY17B030010)。
文摘The hydrogenation of levulinic acid(LA)to c-valerolactone(GVL)by using water as solvent is a crucial process in the production of fine chemicals from biomass.An ultrathin carbon layer coating CoRu bimetallic catalyst supported on silica(CoRu@C/SiO2)is prepared by using tannis-ligated cobalt-ruthenium complex on silica as precursors,and applied for catalyzed synthesis of GVL from LA.Because of the synergistic effect between cobalt and ruthenium,the addition of small amounts of Ru to Co catalysts can increase the catalytic activity in the aqueous hydrogenation of LA.The ultrathin carbon layer covered on the CoRu bimetallic catalyst can greatly reduce the leaching of active metals.The CoRu@C/SiO2 catalyst achieves high stability and is reused up to 5 runs without significant loss of performance in aqueous hydrogenation of levulinic acid.
文摘Biochip is essentially a bio-microarray device that can perform hundreds or thousands of simultaneous biochemical reactions.[1, 2] It offers the researchers a new way for large-scale genomic, proteomic and functional genomic analyses. The biochips also enable people to quickly screen large numbers of biological analyses for many different purposes, from disease diagnosis to detection of bioterrorism chemical agents.[3]
基金an Albert Einstein Professorship to N.C.Stenseth,a cooperation grant(GJHZ0701-7)supported by the Chinese Academy of Sciences.
文摘Plague has caused the death of hundreds of millions of people throughout the human history.Today this disease is again re-emerging and hence is again becoming an increasing threat to human health in several parts of the world.However,impacts of global climate variation(e.g.El Nino and Southern Oscillation[ENSO])and global warming on plagues are largely unknown.Using cross-spectral analysis and cross-wavelet analysis,we have analyzed the relationship between increase rate of human plague in China during 1871–2003 and the following climate factors(as measured by the Southern Oscillation Index[SOI],Sea Surface Temperature of east Pacific equator[SST]and air Temperature of the Northern Hemisphere[NHT]).We found in the frequency domain that increase rate of human plague was closely associated with SOI and SST.Cross-spectral analysis reveals that significant coherencies between increase rate of human plague and ENSO were found over short periods(2–3 years),medium periods(6–7 years)and long periods(11–12 years,30–40 years).Cross-wavelet analysis reveals that increase rate of human plague oscillates in phase with SOI,but in anti-phase with SST over periods of 2–4 years and approximately 8 years(6–10 years).These results indicate that ENSO-driven climate variation may be important for occurrences of human plague in China.However,there is a need for a further analysis of the underlying mechanism between human plague in China and ENSO.
基金National Basic Research Program(2007CB108904-4)Knowledge Innovation Project of the Chinese Academy of Sciences(KZCX2-YW-415).
文摘Aims To explore whether the trade-off between seed and vegetative reproductive modes is flexible in environments with different amounts of available resources to maintain optimal behaviors.Methods A transition matrix model was established to determine the optimal trade-off between seed and vegetative reproduction in resources–variable habitats.Important Findings The model predicts that plants allocate more resources to seed reproduction when available resources are scarce.With increasing resources,more vegetative propagules are produced.However,if resources keep increasing to a harmful level,plants would switch to seeds again.
基金This work was supported by the National Key Research and Development Program of China[NO.2020YFB1312900]the Science,Technology and Innovation Commission of Shenzhen Municipality[ZDSYS20200811143601004]+1 种基金the Agency for Science,Technology and Research(A*STAR,Singapore)AME Programmatic Funding Scheme[A18A1b0045]the SUTD Digital Manufacturing and Design Center(DManD).
文摘Stretchable strain sensor detects a wide range of strain variation and is therefore a key component in various applications.Unlike traditional ones made of elastomers doped with conductive components or fabricated with liquid conductors,ionically conductive hydrogel-based strain sensors remain conductive under large deformations and are biocompatible.However,dehydration is a challenging issue for the latter.Researchers have developed hydrogel-elastomer-based strain sensors where an elastomer matrix encapsulates a hydrogel circuit to prevent its dehydration.However,the reported multistep approaches are generally time-consuming.Our group recently reported a multimaterial 3D printing approach that enables fast fabrication of such sensors,yet requires a self-built digital-light-processing-based multimaterial 3D printer.Here,we report a simple projection lithography method to fabricate hydrogel-elastomer-based stretchable strain sensors within 5 minutes.This method only requires a UV projector/lamp with photomasks;the chemicals are commercially available;the protocols for preparing the polymer precursors are friendly to users without chemistry background.Moreover,the manufacturing flexibility allows users to readily pattern the sensor circuit and attach the sensor to a 3D printed soft pneumatic actuator to enable strain sensing on the latter.The proposed approach paves a simple and versatile way to fabricate hydrogel-elastomer-based stretchable strain sensors and flexible electronic devices.
基金This work was supported by the Grants from National Natural Science Foundation of China(No.11874316)Scientific Research Fund of Hunan Provincial Education Department(No.18A059)+2 种基金the Hunan Provincial Innovation Foundation for Postgraduate(No.CX2018B321)the Project of Xiangtan Science and Technology Bureau(No.CXY-ZD20172002)Innovative Research Team in University(No.IRT 17R91).
文摘Metal-semiconductor ohmic contacts are required to reduce the energy dissipation for two-dimensional (2D) electronic devices, and phase engineering of 2D transition-metal dichalcogenides (TMDCs) is a promising approach for building ohmic contacts. Here, 2D in-plane 1T′-2H MoTe2 homojunctions were prepared by direct epitaxy via vapor deposition. The interface properties of in-plane 1T′-2H MoTe2 homojunction were investigated in detail by combining experiments, calculations and theories. The ohmic contact properties of 1T′-2H MoTe2 homojunction were proved according to Kelvin force probe microscopy and density functional theory calculations. The charge carriers robust transport in in-plane 1T′-2H MoTe2 homojunction without Fermi-level pinning can be well described by Poisson equation and band alignment. These results indicate that phase engineering of 2D TMDCs is promising to construct ohmic contacts for device applications.
基金This work was supported by the Research Fund for the Taishan Scholar Project of Shandong Province of China and Shandong Provincial Natural Science Foundationof China(No.ZR2019MAO03).
文摘Evolutionary game theory has extensively investigated situations in which several gamesare competing against each other at the same time,but the model only assumes sym-metric interactions in homogeneous environments.Now,the population is consideredin heterogeneous environments,individuals in the population occupy a different qualityof patches,and individual fitness depends not only on the interaction between individ-uals,but also on the quality of the environment.Here,by establishing a mathemati-cal framework,we analyze the natural selection between two strategies and two gamesin heterogeneous environments.Furthermore,we analyze the natural selection of Pris-oner's Dilemma and Hawk-Dove games theoretically to demonstrate the dynamics ofcooperators and defectors in their choice of environment and their respective games.Asexpected,the distribution of games and strategies changes with time.Based on differentinitial population compositions,we also discuss the invasion problem of games from dif-ferent perspectives.To one's surprise,we can find that good quality patches attract allindividuals;the long-term dynamics in invariant rich environments is the same as thedynamics of symmetric interactions in homogeneous environments.
基金supported by the National Key Research and Development Program of China(No.2016YFD0500603)the National Natural Science Foundation of China(Nos.61601292 and 61775140)the Shanghai Science and Technology Commission(Nos.17060502500 and 17JC1400601)
文摘A rapid and cost-effective method for fabricating mini lens arrays is proposed. The lenses are made of silicone oil droplets and filled inside a polydimethylsiloxane(PDMS) elastomer. The lens arrays of different initial focal lengths and apertures can be fabricated by using the droplets of different volumes. Due to good elastic behavior of PDMS, the droplet lenses can be flexibly deformed, and the focal length and numerical aperture can be tuned by applying an external force on the PDMS elastomer. Furthermore, an apparatus for focal length tuning is designed and employed in the imaging system.
基金This research was supported by the National Natural Science Foundation of China （No. 30870397） and the State Key Laboratory of Vegetation and Environmental Change.
