Silver-loaded MnO_2 nanomaterials（Ag/MnO_2）,including Ag/α-MnO_2,Ag/β-MnO_2,Ag/γ-MnO_2and Ag/δ-MnO_2 nanorods,were prepared with hydrothermal and impregnation methods.The bactericidal activities of four types of...Silver-loaded MnO_2 nanomaterials（Ag/MnO_2）,including Ag/α-MnO_2,Ag/β-MnO_2,Ag/γ-MnO_2and Ag/δ-MnO_2 nanorods,were prepared with hydrothermal and impregnation methods.The bactericidal activities of four types of Ag/MnO_2 nanomaterials against Escherichia coli were investigated and an inactivation mechanism involving Ag~＋ and reactive oxygen species（ROS）was also proposed.The bactericidal activities of Ag/MnO_2 depended on the MnO_2 crystal phase.Among these nanomaterials,Ag/β^-MnO_2 showed the highest bactericidal activity.There was a 6-log decrease in E.coli survival number after treatment with Ag/β^-MnO_2 for120 min.The results of 5,5-dimethyl-l-pyrroline-N-oxide spin-trapping measurements by electron spin resonance indicate OH and O_2^- formation with addition of Ag/β-MnO_2,Ag/γ-MnO_2 or Ag/δ-MnO_2.The strongest peak of OH appeared for Ag/β-MnO_2,while no OH or ·O_2^-signal was found over Ag/α-MnO_2.Through analysis of electron spin resonance（ESR） and Ag＋elution results,it could be deduced that the toxicity of Ag~＋ eluted from Ag/MnO_2 nanomaterials and ROS played the main roles during the bactericidal process.Silver showed the highest dispersion on the surface of β-MnO_2,which promoted ROS formation and the increase of bactericidal activity.Experimental results also indicated that Ag/MnO_2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane.展开更多
In order to measure the rotation angle error of the worm and gear mechanisms in the atmospheric dispersion corrector( ADC),a novel measurement system based on the autocollimator is designed in this paper.Based on the ...In order to measure the rotation angle error of the worm and gear mechanisms in the atmospheric dispersion corrector( ADC),a novel measurement system based on the autocollimator is designed in this paper.Based on the position relations between the shaft and spot converged by rays of autocollimator,the rotation angle can be calculated quickly and conveniently using a brief algorithm. An optical wedge is introduced to the measurement system for suppressing the awful measuring error caused by the axial wobbly error. The measurement system can measure the shaft rotation angle at any rotation position,which is the novel usage of the two-dimensional autocollimator. Its optical layout is very simple. Only an optical wedge and two plane mirrors are needed besides the autocollimator. The measurement accuracy of the proposed method is less than±0.5 arcmin. In the measurement of two worms and gears mechanisms in ADC,the rotation angle error are±0.05° and ±0.07° respectively,which all satisfies the design demand( ±0.1°). The proposed measurement system can be also suits for some engineering fields.展开更多
A foundation of the modern technology that uses single-crystal silicon has been the growth of highquality single-crystal Si ingots with diameters up to 12 inches or larger. For many applications of graphene, large-are...A foundation of the modern technology that uses single-crystal silicon has been the growth of highquality single-crystal Si ingots with diameters up to 12 inches or larger. For many applications of graphene, large-area high-quality(ideally of single-crystal) material will be enabling. Since the first growth on copper foil a decade ago, inch-sized single-crystal graphene has been achieved. We present here the growth, in 20 min, of a graphene film of(5 ×50) cm^2 dimension with >99% ultra-highly oriented grains.This growth was achieved by:(1) synthesis of metre-sized single-crystal Cu(1 1 1) foil as substrate;(2)epitaxial growth of graphene islands on the Cu(1 1 1) surface;(3) seamless merging of such graphene islands into a graphene film with high single crystallinity and(4) the ultrafast growth of graphene film.These achievements were realized by a temperature-gradient-driven annealing technique to produce single-crystal Cu(1 1 1) from industrial polycrystalline Cu foil and the marvellous effects of a continuous oxygen supply from an adjacent oxide. The as-synthesized graphene film, with very few misoriented grains(if any), has a mobility up to ~23,000 cm^2 V^(-1)s^(-1)at 4 K and room temperature sheet resistance of ~230 Ω/□. It is very likely that this approach can be scaled up to achieve exceptionally large and high-quality graphene films with single crystallinity, and thus realize various industrial-level applications at a low cost.展开更多
The detection mission of gravitational waves in space is that the accuracy of the long-baseline intersatellite laser interferometry on the million-kilometer order needs to reach the order of 8 pm/Hz.Among all noise so...The detection mission of gravitational waves in space is that the accuracy of the long-baseline intersatellite laser interferometry on the million-kilometer order needs to reach the order of 8 pm/Hz.Among all noise sources that affect the interferometry accuracy,tilt-to-length(TTL)coupling noise is the second largest source of noise after shot noise.This paper focuses on studying the contribution of TTL coupling noise of the telescope system in the intersatellite scientific interferometer.By referring to the laser interferometer space antenna(LISA)’s noise budget,TTL coupling noise is required to be within±25μm/rad(±300μrad).Therefore,this paper focuses on studying both the mechanism of TTL coupling noise due to the noise sources of the telescope and the method of suppressing the TTL noise,which can lay a foundation for noise distribution and the development of engineering prototypes in subsequent tasks.展开更多
The performance of an optical system with sensitive line-of-sight(LOS)is influenced by rotational vibration.In view of this,a design methodology is proposed for a passive vibration isolation system in an optical syste...The performance of an optical system with sensitive line-of-sight(LOS)is influenced by rotational vibration.In view of this,a design methodology is proposed for a passive vibration isolation system in an optical system with sensitive LOS.Rotational vibration is attributed to two sources:transmitted from the mounting base and generated by modal coupling.Therefore,the elimination of the rotational vibration caused by coupling becomes an important part of the design of the isolation system.Additionally,the decoupling conditions of the system can be obtained.When the system is totally decoupled,the vibration on each degree of freedom(DOF)can be analyzed independently.Therefore,the stiffness and damping coefficient on each DOF could be obtained by limiting the vibration transmissibility,in accordance to actual requirements.The design of a vibration isolation system must be restricted by the size and shape of the payload and the installation space,and the layout constrains are thus also discussed.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51208497)the National High Technology Research and Development Program of China(No.2012AA062702)International S&T Cooperation Program of China(2013DFM90110)
文摘Silver-loaded MnO_2 nanomaterials（Ag/MnO_2）,including Ag/α-MnO_2,Ag/β-MnO_2,Ag/γ-MnO_2and Ag/δ-MnO_2 nanorods,were prepared with hydrothermal and impregnation methods.The bactericidal activities of four types of Ag/MnO_2 nanomaterials against Escherichia coli were investigated and an inactivation mechanism involving Ag~＋ and reactive oxygen species（ROS）was also proposed.The bactericidal activities of Ag/MnO_2 depended on the MnO_2 crystal phase.Among these nanomaterials,Ag/β^-MnO_2 showed the highest bactericidal activity.There was a 6-log decrease in E.coli survival number after treatment with Ag/β^-MnO_2 for120 min.The results of 5,5-dimethyl-l-pyrroline-N-oxide spin-trapping measurements by electron spin resonance indicate OH and O_2^- formation with addition of Ag/β-MnO_2,Ag/γ-MnO_2 or Ag/δ-MnO_2.The strongest peak of OH appeared for Ag/β-MnO_2,while no OH or ·O_2^-signal was found over Ag/α-MnO_2.Through analysis of electron spin resonance（ESR） and Ag＋elution results,it could be deduced that the toxicity of Ag~＋ eluted from Ag/MnO_2 nanomaterials and ROS played the main roles during the bactericidal process.Silver showed the highest dispersion on the surface of β-MnO_2,which promoted ROS formation and the increase of bactericidal activity.Experimental results also indicated that Ag/MnO_2 induced the production of intracellular ROS and disruption of the cell wall and cell membrane.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.11174274,11174279,61205021 and 11204299)
文摘In order to measure the rotation angle error of the worm and gear mechanisms in the atmospheric dispersion corrector( ADC),a novel measurement system based on the autocollimator is designed in this paper.Based on the position relations between the shaft and spot converged by rays of autocollimator,the rotation angle can be calculated quickly and conveniently using a brief algorithm. An optical wedge is introduced to the measurement system for suppressing the awful measuring error caused by the axial wobbly error. The measurement system can measure the shaft rotation angle at any rotation position,which is the novel usage of the two-dimensional autocollimator. Its optical layout is very simple. Only an optical wedge and two plane mirrors are needed besides the autocollimator. The measurement accuracy of the proposed method is less than±0.5 arcmin. In the measurement of two worms and gears mechanisms in ADC,the rotation angle error are±0.05° and ±0.07° respectively,which all satisfies the design demand( ±0.1°). The proposed measurement system can be also suits for some engineering fields.
基金supported by National Key R&D Program of China (2016YFA0300903, 2016YFA0300802, 2014CB932500 and 2016YFA0200101)National Natural Science Foundation of China (51522201, 11474006, 11327902, 11234001, 21525310, 91433102 and 21573186)+1 种基金Postdoctoral Innovative Personnel Support Program (BX201700014)National Program for Thousand Young Talents of China and the Institute for Basic Science (IBS-R019-D1) of Korea
文摘A foundation of the modern technology that uses single-crystal silicon has been the growth of highquality single-crystal Si ingots with diameters up to 12 inches or larger. For many applications of graphene, large-area high-quality(ideally of single-crystal) material will be enabling. Since the first growth on copper foil a decade ago, inch-sized single-crystal graphene has been achieved. We present here the growth, in 20 min, of a graphene film of(5 ×50) cm^2 dimension with >99% ultra-highly oriented grains.This growth was achieved by:(1) synthesis of metre-sized single-crystal Cu(1 1 1) foil as substrate;(2)epitaxial growth of graphene islands on the Cu(1 1 1) surface;(3) seamless merging of such graphene islands into a graphene film with high single crystallinity and(4) the ultrafast growth of graphene film.These achievements were realized by a temperature-gradient-driven annealing technique to produce single-crystal Cu(1 1 1) from industrial polycrystalline Cu foil and the marvellous effects of a continuous oxygen supply from an adjacent oxide. The as-synthesized graphene film, with very few misoriented grains(if any), has a mobility up to ~23,000 cm^2 V^(-1)s^(-1)at 4 K and room temperature sheet resistance of ~230 Ω/□. It is very likely that this approach can be scaled up to achieve exceptionally large and high-quality graphene films with single crystallinity, and thus realize various industrial-level applications at a low cost.
基金This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA15020000).
文摘The detection mission of gravitational waves in space is that the accuracy of the long-baseline intersatellite laser interferometry on the million-kilometer order needs to reach the order of 8 pm/Hz.Among all noise sources that affect the interferometry accuracy,tilt-to-length(TTL)coupling noise is the second largest source of noise after shot noise.This paper focuses on studying the contribution of TTL coupling noise of the telescope system in the intersatellite scientific interferometer.By referring to the laser interferometer space antenna(LISA)’s noise budget,TTL coupling noise is required to be within±25μm/rad(±300μrad).Therefore,this paper focuses on studying both the mechanism of TTL coupling noise due to the noise sources of the telescope and the method of suppressing the TTL noise,which can lay a foundation for noise distribution and the development of engineering prototypes in subsequent tasks.
基金This work was supported by the Strategic Priority Research Program of the Chinese Academy of Science(Grant No.XDA1502070404)the Projects of Science Technology Development Plan of Jilin Province(Grant No.20190302102GX).
文摘The performance of an optical system with sensitive line-of-sight(LOS)is influenced by rotational vibration.In view of this,a design methodology is proposed for a passive vibration isolation system in an optical system with sensitive LOS.Rotational vibration is attributed to two sources:transmitted from the mounting base and generated by modal coupling.Therefore,the elimination of the rotational vibration caused by coupling becomes an important part of the design of the isolation system.Additionally,the decoupling conditions of the system can be obtained.When the system is totally decoupled,the vibration on each degree of freedom(DOF)can be analyzed independently.Therefore,the stiffness and damping coefficient on each DOF could be obtained by limiting the vibration transmissibility,in accordance to actual requirements.The design of a vibration isolation system must be restricted by the size and shape of the payload and the installation space,and the layout constrains are thus also discussed.
