A colony of macro-fossils Akouemma hemisphaeria has been described in the Paleoproterozoic sedimentary basin of Okondja, Gabon. These fossils are classified into two groups according to their spheroidal or elongated f...A colony of macro-fossils Akouemma hemisphaeria has been described in the Paleoproterozoic sedimentary basin of Okondja, Gabon. These fossils are classified into two groups according to their spheroidal or elongated forms. The spheroidal shapes are similar, have a tripartite structure with two hemispheres and a median disc and gradually pass to the elongated forms. These elongated forms have a pronounced bipartite tendency to two “hemispheres” separated by a median surface, and often have several ovoid “pieces” attached. The elongated specimens show both lateral growth marks and signs of fission. Growth marks are characterized by unidirectional homogeneous side elongations and lateral bud-like protuberances. The signs of fission are marked by circular furrows perpendicular to the direction of elongation, called “constriction furrows” with varying depths depending on the degree of fission of the specimen and internal vertical “division planes”. All of these ovoid and elongated specimens have undergone significant initial deformations due mainly to mutual lateral compressions in tabular beds. The Akouemma hemisphaeria macro-organisms, which were primitive probably sessile organisms, lived on the seafloor. They provide the oldest known record of macro-organisms on Earth having vegetative growth and asexual reproduction by budding, lateral elongation and fission. Their mutual lateral deformations would result from their growth.展开更多
The computed tomography was applied to setting STIM(Scanning Transmission Ion Microscopy) projections recorded at the Fudan Ion Beam Laboratory.In this work,in order to visualize the three-dimensional mass density dis...The computed tomography was applied to setting STIM(Scanning Transmission Ion Microscopy) projections recorded at the Fudan Ion Beam Laboratory.In this work,in order to visualize the three-dimensional mass density distribution in several specimens,example for a test structure of hollow gold cyliner was presented together with a detailed description of the developed system,including data reconstruction code(Tomorebuild 2) and image display software(AMIRA).Future development will allow the particle induced X-ray emission tomography for elemental analysis of micrometer-sized samples.展开更多
The study of exotic decay modes of nuclei near the proton drip line is pivotal for nuclear-structure physics inunderstanding the role of isospin impurity in the states of outermost imbalance of the proton and neutron ...The study of exotic decay modes of nuclei near the proton drip line is pivotal for nuclear-structure physics inunderstanding the role of isospin impurity in the states of outermost imbalance of the proton and neutron numberswith respect to stable nuclei. In recent years, advancements in experimental technique permit us to reveal thestructure of these nuclei by researching -delayed one- and two-proton radioactivity[1]. The -delayed three-protondecay had even been discovered, see Ref. [2]. The mechanism of a -delayed decay involves rst a decay, withthe highest probability for a superallowed decay to the isobaric analogue state (IAS), followed by a proton ormulti-particle emission. This second-stage proton (or multi-particle) emission from the high-lying IAS is isospin-forbidden, while decay from Gamow-Teller populated states may proceed according to the isospin-symmetry limit.A precisely measured exotic decay scheme and branching ratios (BRs) for an isospin-forbidden and/or allowedparticle emission provide a stringent test and constraint for a microscopic approach that takes into account ofisospin non-conservation (INC) consistently in all considered physics processes, i.e., decay, proton emission andelectromagnetic de-excitation.展开更多
Electron energy levels and positron states have been calculated for cadmium and zinc chalcogenide compounds within the pseudo-potential approach and the independent particle model.Furthermore,the present contribution ...Electron energy levels and positron states have been calculated for cadmium and zinc chalcogenide compounds within the pseudo-potential approach and the independent particle model.Furthermore,the present contribution deals with the electron and positron chemical potentials allowing the calculation of the positron affinity to different materials of interest and hetero-structures formed by these materials.Besides,we here determine the positron diffusion constant by means of the positron deformation potential.An attempt has been made to scale positron affinity and diffusion constant with the lattice constant and the band gap energy,respectively.Such scaling is found to be not possible.The information gathered by the present study is of prime importance for a better understanding of positron trapping at interfaces and precipitates and should be useful in slow positron beam experiments.展开更多
Recently, we have constructed a new set of isospin non-conserving (INC) shell-model Hamiltonians as a combinationof isospin conserving (IC) Hamiltonian, Coulomb interaction and effective isospin-symmetry breaking forc...Recently, we have constructed a new set of isospin non-conserving (INC) shell-model Hamiltonians as a combinationof isospin conserving (IC) Hamiltonian, Coulomb interaction and effective isospin-symmetry breaking forcesof nuclear origin[1]. The advantage is that Coulomb effects are taken into account with great care, thus the new ap-Fig. 1 (color online) The comparison of resonant rates of23Al(p;)24Si calculated by IC and INC Hamiltonians. TheINC Hamiltonians of OB+USD, OB+USDA, OB+USDBwere constructed in Ref. [5]; whereas (cd-USD), (cd-USDA),(cd-USDB) are INC Hamiltonians in Ref. [1]. USD, USDA,USDB are IC Hamiltonians in Ref. [6].proach allows one to describe more accurately and topredict unknown nuclear level schemes and decay modes.Since the approximate isospin-symmetry becomes broken,a realistic amount of isospin-mixing in nuclearstates is thus introduced. Among numerous applicationsto the structure of proton-rich nuclei, we usedthe new Hamiltonian to calculate resonant reaction andnon-resonant reaction (direct capture) rates of radiativeproton-capture reactions important for astrophysical rpprocess.展开更多
We have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet[Marquès et al.,Phys.Plasmas 28,023103(2021)].In a continuation of this nu...We have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet[Marquès et al.,Phys.Plasmas 28,023103(2021)].In a continuation of this numerical work,we study experimentally the influence of the tailoring on proton acceleration driven by a high-intensity picosecond laser in three cases:without tailoring,by tailoring only the entrance side of the picosecond laser,and by tailoring both sides of the gas jet.Without tailoring,the acceleration is transverse to the laser axis,with a low-energy exponential spectrum,produced by Coulomb explosion.When the front side of the gas jet is tailored,a forward acceleration appears,which is significantly enhanced when both the front and back sides of the plasma are tailored.This forward acceleration produces higher-energy protons,with a peaked spectrum,and is in good agreement with the mechanism of collisionless shock acceleration(CSA).The spatiotemporal evolution of the plasma profile is characterized by optical shadowgraphy of a probe beam.The refraction and absorption of this beam are simulated by post-processing 3D hydrodynamic simulations of the plasma tailoring.Comparison with the experimental results allows estimation of the thickness and near-critical density of the plasma slab produced by tailoring both sides of the gas jet.These parameters are in good agreement with those required for CSA.展开更多
Metallurgical wastewaters contain high concentrations of sulfate,up to 15 g L^(-1).Sulfate-reducing bioreactors are employed to treat these wastewaters,reducing sulfates to sulfides which subsequently coprecipitate me...Metallurgical wastewaters contain high concentrations of sulfate,up to 15 g L^(-1).Sulfate-reducing bioreactors are employed to treat these wastewaters,reducing sulfates to sulfides which subsequently coprecipitate metals.Sulfate loading and reduction rates are typically restricted by the total H2S concentration.Sulfide stripping,sulfide precipitation and dilution are the main strategies employed to minimize inhibition by H2S,but can be adversely compromised by suboptimal sulfate reduction,clogging and additional energy costs.Here,metallurgical wastewater was treated for over 250 days using two hydrogenotrophic granular activated carbon expanded bed bioreactors without additional removal of sulfides.H2S toxicity was minimized by operating at pH 8±0.15,resulting in an average sulfate removal of 7.08±0.08 g L^(-1),sulfide concentrations of 2.1±0.2 g L^(-1) and peaks up to 2.3±0.2 g L^(-1).A sulfate reduction rate of 20.6±0.9 g L^(-1)d^(-1) was achieved,with maxima up to 27.2 g L^(-1)d^(-1),which is among the highest reported considering a literature review of 39 studies.The rates reported here are 6e8 times higher than those reported for other reactors without active sulfide removal and the only reported for expanded bed sulfate-reducing bioreactors using H2.By increasing the influent sulfate concentration and maintaining high sulfide concentrations,sulfate reducers were promoted while fermenters and methanogens were suppressed.Industrial wastewater containing 4.4 g L^(-1) sulfate,0.036 g L^(-1) nitrate and various metals(As,Fe,Tl,Zn,Ni,Sb,Co and Cd)was successfully treated with all metal(loid)s,nitrates and sulfates removed below discharge limits.展开更多
The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neut...The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.展开更多
文摘A colony of macro-fossils Akouemma hemisphaeria has been described in the Paleoproterozoic sedimentary basin of Okondja, Gabon. These fossils are classified into two groups according to their spheroidal or elongated forms. The spheroidal shapes are similar, have a tripartite structure with two hemispheres and a median disc and gradually pass to the elongated forms. These elongated forms have a pronounced bipartite tendency to two “hemispheres” separated by a median surface, and often have several ovoid “pieces” attached. The elongated specimens show both lateral growth marks and signs of fission. Growth marks are characterized by unidirectional homogeneous side elongations and lateral bud-like protuberances. The signs of fission are marked by circular furrows perpendicular to the direction of elongation, called “constriction furrows” with varying depths depending on the degree of fission of the specimen and internal vertical “division planes”. All of these ovoid and elongated specimens have undergone significant initial deformations due mainly to mutual lateral compressions in tabular beds. The Akouemma hemisphaeria macro-organisms, which were primitive probably sessile organisms, lived on the seafloor. They provide the oldest known record of macro-organisms on Earth having vegetative growth and asexual reproduction by budding, lateral elongation and fission. Their mutual lateral deformations would result from their growth.
基金Supported by Chinese National Science Foundation under the Grant(No.10975034)
文摘The computed tomography was applied to setting STIM(Scanning Transmission Ion Microscopy) projections recorded at the Fudan Ion Beam Laboratory.In this work,in order to visualize the three-dimensional mass density distribution in several specimens,example for a test structure of hollow gold cyliner was presented together with a detailed description of the developed system,including data reconstruction code(Tomorebuild 2) and image display software(AMIRA).Future development will allow the particle induced X-ray emission tomography for elemental analysis of micrometer-sized samples.
文摘The study of exotic decay modes of nuclei near the proton drip line is pivotal for nuclear-structure physics inunderstanding the role of isospin impurity in the states of outermost imbalance of the proton and neutron numberswith respect to stable nuclei. In recent years, advancements in experimental technique permit us to reveal thestructure of these nuclei by researching -delayed one- and two-proton radioactivity[1]. The -delayed three-protondecay had even been discovered, see Ref. [2]. The mechanism of a -delayed decay involves rst a decay, withthe highest probability for a superallowed decay to the isobaric analogue state (IAS), followed by a proton ormulti-particle emission. This second-stage proton (or multi-particle) emission from the high-lying IAS is isospin-forbidden, while decay from Gamow-Teller populated states may proceed according to the isospin-symmetry limit.A precisely measured exotic decay scheme and branching ratios (BRs) for an isospin-forbidden and/or allowedparticle emission provide a stringent test and constraint for a microscopic approach that takes into account ofisospin non-conservation (INC) consistently in all considered physics processes, i.e., decay, proton emission andelectromagnetic de-excitation.
文摘Electron energy levels and positron states have been calculated for cadmium and zinc chalcogenide compounds within the pseudo-potential approach and the independent particle model.Furthermore,the present contribution deals with the electron and positron chemical potentials allowing the calculation of the positron affinity to different materials of interest and hetero-structures formed by these materials.Besides,we here determine the positron diffusion constant by means of the positron deformation potential.An attempt has been made to scale positron affinity and diffusion constant with the lattice constant and the band gap energy,respectively.Such scaling is found to be not possible.The information gathered by the present study is of prime importance for a better understanding of positron trapping at interfaces and precipitates and should be useful in slow positron beam experiments.
文摘Recently, we have constructed a new set of isospin non-conserving (INC) shell-model Hamiltonians as a combinationof isospin conserving (IC) Hamiltonian, Coulomb interaction and effective isospin-symmetry breaking forcesof nuclear origin[1]. The advantage is that Coulomb effects are taken into account with great care, thus the new ap-Fig. 1 (color online) The comparison of resonant rates of23Al(p;)24Si calculated by IC and INC Hamiltonians. TheINC Hamiltonians of OB+USD, OB+USDA, OB+USDBwere constructed in Ref. [5]; whereas (cd-USD), (cd-USDA),(cd-USDB) are INC Hamiltonians in Ref. [1]. USD, USDA,USDB are IC Hamiltonians in Ref. [6].proach allows one to describe more accurately and topredict unknown nuclear level schemes and decay modes.Since the approximate isospin-symmetry becomes broken,a realistic amount of isospin-mixing in nuclearstates is thus introduced. Among numerous applicationsto the structure of proton-rich nuclei, we usedthe new Hamiltonian to calculate resonant reaction andnon-resonant reaction (direct capture) rates of radiativeproton-capture reactions important for astrophysical rpprocess.
基金funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No.871124 Laserlab-Europeby Grant No.ANR-17-CE30-0026-Pinnacle from the Agence Nationale de la Recherche.
文摘We have recently proposed a new technique of plasma tailoring by laser-driven hydrodynamic shockwaves generated on both sides of a gas jet[Marquès et al.,Phys.Plasmas 28,023103(2021)].In a continuation of this numerical work,we study experimentally the influence of the tailoring on proton acceleration driven by a high-intensity picosecond laser in three cases:without tailoring,by tailoring only the entrance side of the picosecond laser,and by tailoring both sides of the gas jet.Without tailoring,the acceleration is transverse to the laser axis,with a low-energy exponential spectrum,produced by Coulomb explosion.When the front side of the gas jet is tailored,a forward acceleration appears,which is significantly enhanced when both the front and back sides of the plasma are tailored.This forward acceleration produces higher-energy protons,with a peaked spectrum,and is in good agreement with the mechanism of collisionless shock acceleration(CSA).The spatiotemporal evolution of the plasma profile is characterized by optical shadowgraphy of a probe beam.The refraction and absorption of this beam are simulated by post-processing 3D hydrodynamic simulations of the plasma tailoring.Comparison with the experimental results allows estimation of the thickness and near-critical density of the plasma slab produced by tailoring both sides of the gas jet.These parameters are in good agreement with those required for CSA.
基金This research was supported by Flanders Innovation&Entrepreneurship(VLAIO,HBC.217.000)the Research&Development Umicore Group.JVL is supported by Ghent University Bijzonder Onderzoeksfonds(BOF)BOF.GOA.2015.0002.01 and BOF15/GOA/006,while KF is supported by BOF/PDO/2020/0020+1 种基金KR is supported by a BOF GOA grant(BOF19/GOA/026)LB is supported by Ghent University Bijzonder Onderzoeksfonds BOF20/PDO/025.
文摘Metallurgical wastewaters contain high concentrations of sulfate,up to 15 g L^(-1).Sulfate-reducing bioreactors are employed to treat these wastewaters,reducing sulfates to sulfides which subsequently coprecipitate metals.Sulfate loading and reduction rates are typically restricted by the total H2S concentration.Sulfide stripping,sulfide precipitation and dilution are the main strategies employed to minimize inhibition by H2S,but can be adversely compromised by suboptimal sulfate reduction,clogging and additional energy costs.Here,metallurgical wastewater was treated for over 250 days using two hydrogenotrophic granular activated carbon expanded bed bioreactors without additional removal of sulfides.H2S toxicity was minimized by operating at pH 8±0.15,resulting in an average sulfate removal of 7.08±0.08 g L^(-1),sulfide concentrations of 2.1±0.2 g L^(-1) and peaks up to 2.3±0.2 g L^(-1).A sulfate reduction rate of 20.6±0.9 g L^(-1)d^(-1) was achieved,with maxima up to 27.2 g L^(-1)d^(-1),which is among the highest reported considering a literature review of 39 studies.The rates reported here are 6e8 times higher than those reported for other reactors without active sulfide removal and the only reported for expanded bed sulfate-reducing bioreactors using H2.By increasing the influent sulfate concentration and maintaining high sulfide concentrations,sulfate reducers were promoted while fermenters and methanogens were suppressed.Industrial wastewater containing 4.4 g L^(-1) sulfate,0.036 g L^(-1) nitrate and various metals(As,Fe,Tl,Zn,Ni,Sb,Co and Cd)was successfully treated with all metal(loid)s,nitrates and sulfates removed below discharge limits.
基金This work was supported by the Chinese Academy of Sciences,the National Key R&D Program of China,the CAS Center for Excellence in Particle Physics,the Joint Large Scale Scientific Facility Funds of the NSFC and CAS,Wuyi University,and the Tsung-Dao Lee Instiute of Shanghai Jiao Tong University in China,the In stiut National de Physique Nucleaire et de Physique de Particules(IN2P3)in France,the Istituto Nazionale di Fisica Nucleare(INFN)in Italy,the Fond de la Recherche Scintifique(F.R.S-FNRS)and FWO under the"Excellence of Science-EOS"in Belgium,the Conselho Nacional de Desenvolvimento Cientificoce Tecnologico in Brazil,the Agencia Nacional de Investigacion y Desrrollo in Chile,the Charles University Research Centre and the Ministry of Education,Youth,and Sports in Czech Republic,the Deutsche Forschungsgemeinschaft(DFG),the Helmholtz Association,and the Cluster of Exellence PRISMA+in Germany,the Joint Institute of Nuclear Research(JINR),Lomonosov Moscow State University,and Russian Foundation for Basic Research(RFBR)in Russia,the MOST and MOE in Taiwan,the Chu-lalongkorm University and Suranaree University of Technology in Thailand,and the University of aliformia at Irvine in USA.
文摘The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.
