Depleted shergottites record unique information about the primary composition and differentiation of the mantle of Mars.Their petrology,geochemistry,and cosmic ray exposure and crystallization ages suggest that most o...Depleted shergottites record unique information about the primary composition and differentiation of the mantle of Mars.Their petrology,geochemistry,and cosmic ray exposure and crystallization ages suggest that most of them were excavated by a single young impact in the Amazonian-aged lava flows of the Tharsis and Elysium volcanic provinces.However,the difficulties of deriving consistent model ages for individual craters and inadequate evaluation of 3-7 km craters capable of ejecting martian meteorites have not been settled.Here we perform detailed geological investigations and crater statistics in patches of impact melt deposits for potential source craters of depleted shergottites with D>3 km,especially those in the Tharsis and Elysium volcanic provinces.By excluding the effect of heterogeneous textures across ejecta deposits,which hinder straightforward extraction of superposed production populations,our systematically updated model ages reveal that Chakpar crater at the northern flank of Ascraeus Mons is the best-fit candidate.The local context of this crater permits establishing a link between the meteorites and specific lava flows.The long-lived volcanic center here may experience an eruption and/or local deposition hiatus for about 1.8 billion years,and abundant subsurface water existed when the impact occurred at about 1.1 million years.展开更多
A sensitive room-temperature metal-semiconductor-metal(MSM)structure is fabricated on high-resistivity silicon substrates(ρ>4000 Ω·cm)for terahertz(THz)detection by utilizing the photoconductive effect.When ...A sensitive room-temperature metal-semiconductor-metal(MSM)structure is fabricated on high-resistivity silicon substrates(ρ>4000 Ω·cm)for terahertz(THz)detection by utilizing the photoconductive effect.When radiation is absorbed by the nitrogen-rich niobium nitride,the number of free electrons and electrical conductivity increase.The detector without an attached antenna boasts a voltage responsivity of 7058 V/W at a frequency of 310 GHz as well as small noise density of 3.5 nV/Hz^(0.5) for a noise equivalent power of about 0.5 pW/Hz^(0.5).The device fabricated by the standard silicon processing technology has large potential in high-sensitivity THz remote sensing,communication,and materials detection.展开更多
The tunable propagation properties of 3D Dirac semimetal(DSM)-supported dielectric-loaded surface plasmons structures have been investigated in the THz regime,including the influences of the Fermi level of 3D DSM laye...The tunable propagation properties of 3D Dirac semimetal(DSM)-supported dielectric-loaded surface plasmons structures have been investigated in the THz regime,including the influences of the Fermi level of 3D DSM layer,the fiber shape and operation frequencies.The results indicate that the shape of dielectric fiber affects the hybrid mode significantly,on the condition that if ax(the semi-minor axis length of the dielectric semi-ellipse)is relatively small,the fiber shows good mode confinement and low loss simultaneously,and the figure of merit reaches more than 200.The propagation property can be manipulated in a wide range by changing the Fermi level of 3D DSM,e.g.if the Fermi level varies in the range of 0.05 eV–0.15 eV,the propagation length changes in the range of 9.073×10^(3)–2.715×10^(4)μm,and the corresponding modulation depth is 66.5%.These results are very helpful to understand the tunable mechanisms of the 3D DSM plasmonic devices,such as switchers,modulators,and sensors.展开更多
Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Rama...Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure∼13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.展开更多
Green's relations and generalized Green's relations play a fundamental role in the study of semigroups.GV-semigroups are the generalizations of completely regular semigroups in the range of π-regular semigrou...Green's relations and generalized Green's relations play a fundamental role in the study of semigroups.GV-semigroups are the generalizations of completely regular semigroups in the range of π-regular semigroups.In this paper,Green's relations and generalized Green's relations on GV-semigroups are considered by the structure of GV-semigroups.D=j and D C D* on GV-semigroups will be proved.展开更多
基金funded by the National Natural Science Foundation of China(Grant Nos.42241108,423B2205,42273040,62227901)the Strategic Priority Research Program of Chinese Academy of Science(Grant No.XDB41000000)。
文摘Depleted shergottites record unique information about the primary composition and differentiation of the mantle of Mars.Their petrology,geochemistry,and cosmic ray exposure and crystallization ages suggest that most of them were excavated by a single young impact in the Amazonian-aged lava flows of the Tharsis and Elysium volcanic provinces.However,the difficulties of deriving consistent model ages for individual craters and inadequate evaluation of 3-7 km craters capable of ejecting martian meteorites have not been settled.Here we perform detailed geological investigations and crater statistics in patches of impact melt deposits for potential source craters of depleted shergottites with D>3 km,especially those in the Tharsis and Elysium volcanic provinces.By excluding the effect of heterogeneous textures across ejecta deposits,which hinder straightforward extraction of superposed production populations,our systematically updated model ages reveal that Chakpar crater at the northern flank of Ascraeus Mons is the best-fit candidate.The local context of this crater permits establishing a link between the meteorites and specific lava flows.The long-lived volcanic center here may experience an eruption and/or local deposition hiatus for about 1.8 billion years,and abundant subsurface water existed when the impact occurred at about 1.1 million years.
基金supported by the Innovation Program for Quantum Science and Technology(No.2021ZD0303401)the Program of Shanghai Academic Research Leader (No.22XD1422100)the National Natural Science Foundation of China(Nos.12141303,12073018 and U1931205)。
文摘A sensitive room-temperature metal-semiconductor-metal(MSM)structure is fabricated on high-resistivity silicon substrates(ρ>4000 Ω·cm)for terahertz(THz)detection by utilizing the photoconductive effect.When radiation is absorbed by the nitrogen-rich niobium nitride,the number of free electrons and electrical conductivity increase.The detector without an attached antenna boasts a voltage responsivity of 7058 V/W at a frequency of 310 GHz as well as small noise density of 3.5 nV/Hz^(0.5) for a noise equivalent power of about 0.5 pW/Hz^(0.5).The device fabricated by the standard silicon processing technology has large potential in high-sensitivity THz remote sensing,communication,and materials detection.
基金the Natural Science Foundation of Shanghai under Grant Nos.21ZR1446500Shanghai Local College Capacity Building Project under Grant No.22010503300 and 21010503200+4 种基金the Research Funding of Shanghai Normal University under Grant No.SK202240National Natural Science Foundation of China under Grant Nos.61674106,12073018,U1931205the Funding of Shanghai Municipal Education Commission under Grant No 2019-01-07-00-02-E00032the Funding of Shanghai Municipality Science and Technology Commission under Grant No 19590746000,20070502400,YDZX20203100002498Student Research Project of Shanghai Normal University(undergraduate)under Grant No.22LKY022.
文摘The tunable propagation properties of 3D Dirac semimetal(DSM)-supported dielectric-loaded surface plasmons structures have been investigated in the THz regime,including the influences of the Fermi level of 3D DSM layer,the fiber shape and operation frequencies.The results indicate that the shape of dielectric fiber affects the hybrid mode significantly,on the condition that if ax(the semi-minor axis length of the dielectric semi-ellipse)is relatively small,the fiber shows good mode confinement and low loss simultaneously,and the figure of merit reaches more than 200.The propagation property can be manipulated in a wide range by changing the Fermi level of 3D DSM,e.g.if the Fermi level varies in the range of 0.05 eV–0.15 eV,the propagation length changes in the range of 9.073×10^(3)–2.715×10^(4)μm,and the corresponding modulation depth is 66.5%.These results are very helpful to understand the tunable mechanisms of the 3D DSM plasmonic devices,such as switchers,modulators,and sensors.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11674231,11974250,and 51772192)the Science and Technology Commission of Shanghai Municipality(Grant Nos.17070502700 and 19070502800)the Shenzhen Development and Reform Commission Foundation for Shenzhen Engineering Research Center for Frontier Materials Synthesis at High Pressures.
文摘Pressure evolution of local structure and vibrational dynamics of the perovskite-type relaxor ferroelectric single crystal of 0.935(Na0.5Bi0.5)TiO3-0.065BaTiO3(NBT-6.5BT)is systematically investigated via in situ Raman spectroscopy.The pressure dependence of phonon modes up to 30GPa reveals two characteristic pressures:one is at around 4.6GPa which corresponds to the rhombohedral-to-tetragonal phase transition,showing that the pressure strongly suppresses the coupling between the off-centered A-and B-site cations;the other structural transition involving the oxygen octahedral tilt and vibration occurs at pressure∼13–15GPa with certain degree of order-disorder transition,evidenced by the abnormal changes of intensity and FWHM in Raman spectrum.
基金Leading Academic Discipline Project of SHNU,China (No.DZL803)Innovation Project of Shanghai Education Committee,China(No.12YZ081)+2 种基金General Scientific Research Project of SHNU,China (No.SK201121)National Natural Science Foundation of China(No.11001046)Fundamental Research Fundation for the Central Universities,China (No.11D10904)
文摘Green's relations and generalized Green's relations play a fundamental role in the study of semigroups.GV-semigroups are the generalizations of completely regular semigroups in the range of π-regular semigroups.In this paper,Green's relations and generalized Green's relations on GV-semigroups are considered by the structure of GV-semigroups.D=j and D C D* on GV-semigroups will be proved.
