Zero thermal expansion materials are important for the practical applications due to their shape stability as changing temperature.The reported concept of average atomic volume is an available method to hunt new zero ...Zero thermal expansion materials are important for the practical applications due to their shape stability as changing temperature.The reported concept of average atomic volume is an available method to hunt new zero thermal expansion materials.Here,according to this concept,a tetragonal tungstate Cs_(2)W_(3)O_(10)with zero expansion has been found.There is no structure phase transition as increasing temperature from 150 K to 573 K.The coefficient of thermal expansion of axes and volume areαa=0.0074×10^(-6)K^(-1),αc=1.63×10^(-6)K^(-1),andαV=1.60×10^(-6)K^(-1),respectively,in the temperature range of 150~573 K.The temperature-and pressure-dependent Raman spectra reveal that the vibrations of WO6octahedra libration modes with positive total anharmonicity and W-O-W bending mode with negative Grüneisen parameter are possibly the origin of zero thermal expansion in Cs_(2)W_(3)O_(10).展开更多
Copolymers which are synthesized by oligomers or homopolymers have quasi-one-dimen sional structures. A tight-binding model was suggested to study the organic quantum-well properties of triblock copolymers xPA/nPPP/yP...Copolymers which are synthesized by oligomers or homopolymers have quasi-one-dimen sional structures. A tight-binding model was suggested to study the organic quantum-well properties of triblock copolymers xPA/nPPP/yPA and xPPP/nPA/yPPP consisting of polyacetylene (PA) and poly(p-phenylene) (PPP). It was found that the electronic density in the lowest conductive state ( LU MO) could be tuned by the ratios of homopolymers and interfacial coupling. The spontaneous quantum tunneling effects will occur in triblock copolymer xPA/nPPP/yPA with the increasing interfacial cou pling.展开更多
Negative thermal expansion(NTE)of materials is an intriguing phenomenon challenging the concept of traditional lattice dynamics and of importance for a variety of applications.Progresses in this field develop markedly...Negative thermal expansion(NTE)of materials is an intriguing phenomenon challenging the concept of traditional lattice dynamics and of importance for a variety of applications.Progresses in this field develop markedly and update continuously our knowledge on the NTE behavior of materials.In this article,we review the most recent understandings on the underlying mechanisms(anharmonic phonon vibration,magnetovolume effect,ferroelectrorestriction and charge transfer)of thermal shrinkage and the development of NTE materials under each mechanism from both the theoretical and experimental aspects.Besides the low frequency optical phonons which are usually accepted as the origins of NTE in framework structures,NTE driven by acoustic phonons and the interplay between anisotropic elasticity and phonons are stressed.Based on the data documented,some problems affecting applications of NTE materials are discussed and strategies for discovering and design novel framework structured NET materials are also presented.展开更多
The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health.Prevention of bacteria spread by the construction of an antibacterial surface takes...The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health.Prevention of bacteria spread by the construction of an antibacterial surface takes precedence over post-infection treatment.Herein,we demonstrate an effective antibacterial surface with strong wear resistance by constructing cationic engineered nanodiamonds(C-NDs).The C-NDs with positive surface potentials interact effectively with bacteria through electrostatic interactions,where the C-NDs act on the phospholipid bilayer and lead to bacterial membrane collapse and rupture through hydrogen bonding and residual surface oxygen-containing reactive groups.In this case,bactericidal rate of 99.99%and bacterial biofilm inhibition rate of more than 80%can be achieved with the C-NDs concentration of 1 mg/mL.In addition,the C-NDs show outstanding antibacterial stability,retaining over 87%of the antibacterial effect after stimulation by adverse environments of heat,acid,and external abrasion.Therefore,an antibacterial surface with high wear resistance obtained by integrating C-NDs with commercial plastics has been demonstrated.The antibacterial surface with a mass fraction of 1 wt.%C-NDs improved abrasion resistance by 3981 times,with 99%killing of adherent bacteria.This work provides an effective strategy for highly efficient antibacterial wear-resistant surface,showing great practical applications in public health environments.展开更多
Humidity sensors with high sensitivity,rapid response,and facile fabrication process for contactless sensing applications have received considerable attention in recent years.Herein,humidity sensors based on hexagonal...Humidity sensors with high sensitivity,rapid response,and facile fabrication process for contactless sensing applications have received considerable attention in recent years.Herein,humidity sensors based on hexagonal boron nitride(h-BN)nanosheets that are synthesized by a facile ultrasonic process have been fabricated,which display an ultrahigh sensitivity of 28,384%at 85%relative humidity(RH),rapid response/recovery time(3.0/5.5 s),and long-term stability in a wide humidity detection range(11%-85%RH),superior to most of the reported humidity sensors.The high sensitivity can be ascribed to the massive hydrophilic functional groups absorbed on the h-BN nanosheet surface.Benefiting from the high humidity sensing performances,contactless Morse code messaging and human writing and speech recognition have been demonstrated.This work demonstrates the great potential of the high-performance h-BN nanosheet-based humidity sensors for future contactless sensing devices.展开更多
基金supported by the National Natural Science Foundation of China(Nos.22071221,21905252)Natural Science Foundation of Henan Province(Nos.212300410086,222301420040 and 222300420325)。
文摘Zero thermal expansion materials are important for the practical applications due to their shape stability as changing temperature.The reported concept of average atomic volume is an available method to hunt new zero thermal expansion materials.Here,according to this concept,a tetragonal tungstate Cs_(2)W_(3)O_(10)with zero expansion has been found.There is no structure phase transition as increasing temperature from 150 K to 573 K.The coefficient of thermal expansion of axes and volume areαa=0.0074×10^(-6)K^(-1),αc=1.63×10^(-6)K^(-1),andαV=1.60×10^(-6)K^(-1),respectively,in the temperature range of 150~573 K.The temperature-and pressure-dependent Raman spectra reveal that the vibrations of WO6octahedra libration modes with positive total anharmonicity and W-O-W bending mode with negative Grüneisen parameter are possibly the origin of zero thermal expansion in Cs_(2)W_(3)O_(10).
基金This work was supported by the National Natural Science Foundation of China ( Grant Nos. 10074040 and 59871024).
文摘Copolymers which are synthesized by oligomers or homopolymers have quasi-one-dimen sional structures. A tight-binding model was suggested to study the organic quantum-well properties of triblock copolymers xPA/nPPP/yPA and xPPP/nPA/yPPP consisting of polyacetylene (PA) and poly(p-phenylene) (PPP). It was found that the electronic density in the lowest conductive state ( LU MO) could be tuned by the ratios of homopolymers and interfacial coupling. The spontaneous quantum tunneling effects will occur in triblock copolymer xPA/nPPP/yPA with the increasing interfacial cou pling.
基金This work was supported by the National Natural Science Foundation of China(Nos.11874328,11774078,and 21905252)China Postdoctoral Science Foundation(No.2019M652558).
文摘Negative thermal expansion(NTE)of materials is an intriguing phenomenon challenging the concept of traditional lattice dynamics and of importance for a variety of applications.Progresses in this field develop markedly and update continuously our knowledge on the NTE behavior of materials.In this article,we review the most recent understandings on the underlying mechanisms(anharmonic phonon vibration,magnetovolume effect,ferroelectrorestriction and charge transfer)of thermal shrinkage and the development of NTE materials under each mechanism from both the theoretical and experimental aspects.Besides the low frequency optical phonons which are usually accepted as the origins of NTE in framework structures,NTE driven by acoustic phonons and the interplay between anisotropic elasticity and phonons are stressed.Based on the data documented,some problems affecting applications of NTE materials are discussed and strategies for discovering and design novel framework structured NET materials are also presented.
基金The authors acknowledge the National Natural Science Foundation of China(Nos.12274378,62075198 and U21A2070)Outstanding Youth Foundation of Henan(No.222300420087)for financial support of this work.
文摘The spread of diseases caused by bacterial adhesion and immobilization in public places constitutes a serious threat to public health.Prevention of bacteria spread by the construction of an antibacterial surface takes precedence over post-infection treatment.Herein,we demonstrate an effective antibacterial surface with strong wear resistance by constructing cationic engineered nanodiamonds(C-NDs).The C-NDs with positive surface potentials interact effectively with bacteria through electrostatic interactions,where the C-NDs act on the phospholipid bilayer and lead to bacterial membrane collapse and rupture through hydrogen bonding and residual surface oxygen-containing reactive groups.In this case,bactericidal rate of 99.99%and bacterial biofilm inhibition rate of more than 80%can be achieved with the C-NDs concentration of 1 mg/mL.In addition,the C-NDs show outstanding antibacterial stability,retaining over 87%of the antibacterial effect after stimulation by adverse environments of heat,acid,and external abrasion.Therefore,an antibacterial surface with high wear resistance obtained by integrating C-NDs with commercial plastics has been demonstrated.The antibacterial surface with a mass fraction of 1 wt.%C-NDs improved abrasion resistance by 3981 times,with 99%killing of adherent bacteria.This work provides an effective strategy for highly efficient antibacterial wear-resistant surface,showing great practical applications in public health environments.
基金This work was supported by the National Natural Science Foundation of China(Nos.12174348,U21A2070,and 62027816)the Young Elite Scientists Sponsorship Program by CAST(No.2021QNRC001)+1 种基金the Natural Science Foundation of Henan Province(No.212300410410)the China Postdoctoral Science Foundation(Nos.2018M630830 and 2019T120631).
文摘Humidity sensors with high sensitivity,rapid response,and facile fabrication process for contactless sensing applications have received considerable attention in recent years.Herein,humidity sensors based on hexagonal boron nitride(h-BN)nanosheets that are synthesized by a facile ultrasonic process have been fabricated,which display an ultrahigh sensitivity of 28,384%at 85%relative humidity(RH),rapid response/recovery time(3.0/5.5 s),and long-term stability in a wide humidity detection range(11%-85%RH),superior to most of the reported humidity sensors.The high sensitivity can be ascribed to the massive hydrophilic functional groups absorbed on the h-BN nanosheet surface.Benefiting from the high humidity sensing performances,contactless Morse code messaging and human writing and speech recognition have been demonstrated.This work demonstrates the great potential of the high-performance h-BN nanosheet-based humidity sensors for future contactless sensing devices.
