Large-scale components of steel and aluminum alloys(Fe-Al)with high bonding strength are highly needed from space exploration to the fabrication of transportation systems.The formation of detrimental intermetallic com...Large-scale components of steel and aluminum alloys(Fe-Al)with high bonding strength are highly needed from space exploration to the fabrication of transportation systems.The formation of detrimental intermetallic compounds at the Al-Fe interface has limited the application range of the Fe-Al components.The modified friction stir additive manufacturing was developed for fabricating large-scale Fe-Al compo-nents with homogenously distributed interfacial amorphous layers rather than detrimental intermetallic compounds.The interfacial amorphous layers comprised an Mg-O rich amorphous layer<20 nm in thick-ness and an Al-Fe-Si amorphous layer<120 nm in thickness.The interfacial amorphous layers exhibited high thermal stability and did not change even after the post-processing heat treatment of heating at 500℃ for 20 min and aging at 170℃ for 7 h.The tensile strengths of the Fe-Al tensile specimens were increased from 160 to 250 MPa after the application of the post-processing heat treatment.The fracture occurred in the aluminum alloys instead of at the dissimilar metal interface,demonstrating that high bonding strength at the Al-Fe interface was enabled by the formation of homogenously distributed interfacial amorphous layers.展开更多
Theδ-Cancrid meteoroid stream forms four active meteor showers which are observable on the Earth annually during January–February and August–September.The stream's definite parent comet has not been established...Theδ-Cancrid meteoroid stream forms four active meteor showers which are observable on the Earth annually during January–February and August–September.The stream's definite parent comet has not been established.We performed a search for near-Earth asteroids(NEAs)associated with this stream.We have followed the backward evolution of the orbital elements of a sample of NEAs and found their orbits at the Earth-crossing positions.Using these orbits,we calculated the theoretical parameters of meteor showers associated with the considered NEAs.We carried out our search for observable active showers that match theoretically predicted ones with published data,and the result turned out that the predicted meteor showers of 13 NEAs were identified with the active showers produced by theδ-Cancrid meteoroid stream.The comet-like orbits of NEAs and established association with active meteor showers indicate their common cometary origin.The NEAs considered are moving within the stream and likely represent the dormant remnants of a parent comet of theδ-Cancrid asteroid-meteoroid complex that disintegrated more than 12 thousand years ago.展开更多
The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on20...The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.展开更多
The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ri...The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ring in Lanzhou.The new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 keV.When compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)keV.The excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field theory.The mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.展开更多
Although fine equiaxed structure benefits both strength and ductility in titanium alloys,it is often considered incompatible with high toughness,for its insufficient ability to deflect propagating cracks compared to c...Although fine equiaxed structure benefits both strength and ductility in titanium alloys,it is often considered incompatible with high toughness,for its insufficient ability to deflect propagating cracks compared to coarse lamellar structure.This work reports an excellent combination of standard Charpy impact toughness(∼100 J)and yield strength(∼820 MPa)in a powder metallurgy titanium alloy with fine equiaxed structure(∼1.5μm),wherein the β matrix exists as equiaxed nodules and fine ligaments for globularization of α grains.The impact curve divided with the“compliance changing rate”(CCR)method indicates that the energy consumed by crack propagation is dominant(∼82%)during the impact process.Fractographic and structural examinations indicate that multiple micro-voids nucleation near boundaries between fine β ligaments and α grains mitigates local stress concentration,and that coordinated deformation between equiaxed β nodules and α grains hinders crack propagation,which together enable the excellent combination of yield strength and impact toughness.Our work provides a new pathway for designing impact-resistant titanium alloys.展开更多
Few-layer molybdenum disulfide（MoS2） is emerging as a promising quasi-two-dimensional material for photonics and optoelectronics, further extending the library of suitable layered nanomaterials with exceptional opti...Few-layer molybdenum disulfide（MoS2） is emerging as a promising quasi-two-dimensional material for photonics and optoelectronics, further extending the library of suitable layered nanomaterials with exceptional optical properties for use in saturable absorber devices that enable short-pulse generation in laser systems. In this work, we catalog and review the nonlinear optical properties of few-layer MoS2, summarize recent progress in processing and integration into saturable absorber devices, and comment on the current status and future perspectives of MoS2-based pulsed lasers.展开更多
基金supported by the National Natu-ral Science Foundation of China(Nos.52375396,52034005,and 51975553)the Liaoning Provincial Department of Science and Technology(No.2023JH2/101300149)+4 种基金the Shenyang Science and Technology Bureau(No.22-315-6-03)and Institute of Metal Re-search,Chinese Academy of Sciences(No.2023-ZD02-01)the Liaoning Province Excellent Youth Foundation(No.2021-YQ-01)the Program of the Youth Innovation Promotion Association of the Chi-nese Academy of Sciences(No.Y2021061)the Bintech-IMR R&D Program(No.GYY-JSBU-2022-002).
文摘Large-scale components of steel and aluminum alloys(Fe-Al)with high bonding strength are highly needed from space exploration to the fabrication of transportation systems.The formation of detrimental intermetallic compounds at the Al-Fe interface has limited the application range of the Fe-Al components.The modified friction stir additive manufacturing was developed for fabricating large-scale Fe-Al compo-nents with homogenously distributed interfacial amorphous layers rather than detrimental intermetallic compounds.The interfacial amorphous layers comprised an Mg-O rich amorphous layer<20 nm in thick-ness and an Al-Fe-Si amorphous layer<120 nm in thickness.The interfacial amorphous layers exhibited high thermal stability and did not change even after the post-processing heat treatment of heating at 500℃ for 20 min and aging at 170℃ for 7 h.The tensile strengths of the Fe-Al tensile specimens were increased from 160 to 250 MPa after the application of the post-processing heat treatment.The fracture occurred in the aluminum alloys instead of at the dissimilar metal interface,demonstrating that high bonding strength at the Al-Fe interface was enabled by the formation of homogenously distributed interfacial amorphous layers.
基金the support from the National Key R&D Intergovernmental Cooperation Program(2023YFE0102300/2022YFE0133700)the Regional Collaborative Innovation Project of Xinjiang(2022E01013)+1 种基金the National Natural Science Foundation of China(12173078)the“Belt and Road”Innovative Talent Exchange Program(DL2023046004)。
文摘Theδ-Cancrid meteoroid stream forms four active meteor showers which are observable on the Earth annually during January–February and August–September.The stream's definite parent comet has not been established.We performed a search for near-Earth asteroids(NEAs)associated with this stream.We have followed the backward evolution of the orbital elements of a sample of NEAs and found their orbits at the Earth-crossing positions.Using these orbits,we calculated the theoretical parameters of meteor showers associated with the considered NEAs.We carried out our search for observable active showers that match theoretically predicted ones with published data,and the result turned out that the predicted meteor showers of 13 NEAs were identified with the active showers produced by theδ-Cancrid meteoroid stream.The comet-like orbits of NEAs and established association with active meteor showers indicate their common cometary origin.The NEAs considered are moving within the stream and likely represent the dormant remnants of a parent comet of theδ-Cancrid asteroid-meteoroid complex that disintegrated more than 12 thousand years ago.
基金supported by the Einstein Probe project,a mission in the Strategic Priority Program on Space Science of CAS(grant Nos.XDA15310000,XDA15052100)in part been supported by the European Union’s Horizon 2020 Program under the AHEAD2020 project(grant No.871158).
文摘The Lobster Eye Imager for Astronomy(LEIA),a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe mission,was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on2022 July 27.In this paper,we introduce the design and on-ground test results of the LEIA instrument.Using stateof-the-art Micro-Pore Optics(MPO),a wide field of view of 346 square degrees(18.6°×18.6°)of the X-ray imager is realized.An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons,and four large-format complementary metal-oxide semiconductor(CMOS)sensors,each of size 6 cm×6 cm,are used as the focal plane detectors.The instrument has an angular resolution of 4’-8’(in terms of FWHM)for the central focal spot of the point-spread function,and an effective area of 2-3 cm^(2) at 1 keV in essentially all the directions within the field of view.The detection passband is 0.5-4 keV in soft X-rays and the sensitivity is2-3×10^(-11) erg s^(-1) cm^(-2)(about 1 milliCrab)with a 1000 s observation.The total weight of LEIA is 56 kg and the power is 85 W.The satellite,with a design lifetime of 2 yr,operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes.LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation,and by optimizing the working setups of the instrumental parameters.In addition,LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band,albeit with limited useful observing time available.
基金Supported in part by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB34000000)the CAS Project for Young Scientists in Basic Research (YSBR-002)+4 种基金the National Nature Science Foundation of China (12135017,12121005,11975280,12105333,12205340,12322507,12305126,12305151)the Gansu Natural Science Foundation (22JR5RA123,23JRRA614)the National Key R&D Program of China (2021YFA1601500)Support from the Youth Innovation Promotion Association of Chinese Academy of Sciences (2021419,2022423)support from Young Scholar of Regional Development,CAS ([2023]15).
文摘The ground-state mass excess of the T_(z)=−2 drip-line nucleus ^(22)Al is measured for the first time as 18103(10)keV using the newly-developed Bρ-defined isochronous mass spectrometry method at the cooler storage ring in Lanzhou.The new mass excess value allowed us to determine the excitation energies of the two low-lying 1+states in ^(22)Al with significantly reduced uncertainties of 51 keV.When compared to the analogue states in its mirror nucleus ^(22)F,the mirror energy differences of the two 1^(+)states in the ^(22)Al-^(22)F mirror pair are determined to be−625(51)keV and−330(51)keV.The excitation energies and mirror energy differences are used to test the state-of-the-art ab initio valence-space in-medium similarity renormalization group calculations with four sets of interactions derived from the chiral effective field theory.The mechanism leading to the large mirror energy differences is investigated and attributed to the occupation of theπs_(1/2) orbital.
基金financially supported by the National Natural Science Foundation of China(No.52371156).
文摘Although fine equiaxed structure benefits both strength and ductility in titanium alloys,it is often considered incompatible with high toughness,for its insufficient ability to deflect propagating cracks compared to coarse lamellar structure.This work reports an excellent combination of standard Charpy impact toughness(∼100 J)and yield strength(∼820 MPa)in a powder metallurgy titanium alloy with fine equiaxed structure(∼1.5μm),wherein the β matrix exists as equiaxed nodules and fine ligaments for globularization of α grains.The impact curve divided with the“compliance changing rate”(CCR)method indicates that the energy consumed by crack propagation is dominant(∼82%)during the impact process.Fractographic and structural examinations indicate that multiple micro-voids nucleation near boundaries between fine β ligaments and α grains mitigates local stress concentration,and that coordinated deformation between equiaxed β nodules and α grains hinders crack propagation,which together enable the excellent combination of yield strength and impact toughness.Our work provides a new pathway for designing impact-resistant titanium alloys.
基金support from the Royal Academy of Engineering (RAEng)
文摘Few-layer molybdenum disulfide（MoS2） is emerging as a promising quasi-two-dimensional material for photonics and optoelectronics, further extending the library of suitable layered nanomaterials with exceptional optical properties for use in saturable absorber devices that enable short-pulse generation in laser systems. In this work, we catalog and review the nonlinear optical properties of few-layer MoS2, summarize recent progress in processing and integration into saturable absorber devices, and comment on the current status and future perspectives of MoS2-based pulsed lasers.
