The deformation behavior of the as-extruded Mg-Y-Ni alloys with different volume fraction of long period stacking ordered(LPSO)phase during tension and compression was investigated by in-situ synchrotron diffraction.T...The deformation behavior of the as-extruded Mg-Y-Ni alloys with different volume fraction of long period stacking ordered(LPSO)phase during tension and compression was investigated by in-situ synchrotron diffraction.The micro-yielding,macro-yielding,tension-compression asymmetry and strain hardening behavior of the alloys were explored by combining with deformation mechanisms.The micro-yielding is dominated by basal slip of dynamic recrystallized(DRXed)grains in tension,while it is dominated by extension twinning of non-dynamic recrystallized(non-DRXed)grains in compression.At macro-yielding,the non-DRXed grains are still elastic deformed in tension and the basal slip of DRXed grains in compression are activated.Meanwhile,the LPSO phase still retains elastic deformation,but can bear more load,so the higher the volume fraction of hard LPSO phase,the higher the tensile/compressive macro-yield strength of the alloys.Benefiting from the low volume fraction of the non-DRXed grains and the delay effect of LPSO andγphases on extension twinning,the as-extruded alloys exhibit excellent tension-compression symmetry.When the volume fraction of LPSO phase reaches∼50%,tension-compression asymmetry is reversed,which is due to the fact that the LPSO phase is stronger in compression than in tension.The tensile strain hardening behavior is dominated by dislocation slip,while the dominate mechanism for compressive strain hardening changes from twinning in theα-Mg grains to kinking of the LPSO phase with increasing volume fraction of LPSO phase.The activation of kinking leads to the constant compressive strain hardening rate of∼2500 MPa,which is significantly higher than the tensile strain hardening rate.展开更多
Delayed γ-ray spectroscopy of^(185)Au was studied at the Argonne Gas-Filled Analyzer.A new isomer at an excitation energy of 1504.2(4) keV with a half-life of 630(80) ns was identified via γ-γ coincidence analysis,...Delayed γ-ray spectroscopy of^(185)Au was studied at the Argonne Gas-Filled Analyzer.A new isomer at an excitation energy of 1504.2(4) keV with a half-life of 630(80) ns was identified via γ-γ coincidence analysis,decaying via a 294.8(3) keV transition.Based on Weisskopf estimates,the multipolarity of the 295 keV transition is assigned to be E1,M1,E2,or M2.Possible configurations for this new isomer are discussed based on configurationconstrained potential energy surface calculations.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
The functionalities of hydrogel-based smart materials are highly related to the electrostatic interactions and molecular polarization associated with the polymer networks and encapsulated water droplets,and therefore ...The functionalities of hydrogel-based smart materials are highly related to the electrostatic interactions and molecular polarization associated with the polymer networks and encapsulated water droplets,and therefore the dielectric responses of the polarizable molecules in the polymer,water,and polymer-water interfaces are particularly attractive,where the properties of polymer-water interfacial molecules remain elusive.Different from extensive dielectric relaxation spectroscopy studies on polymer hydrogel solutions,in this work we investigate the dielectric response of chitosan hydrogels below the water solidifying point(ice-hydrogels)so that the contribution of chitosan-water interfacial molecules can be isolated.It is revealed that the chitosan-water interfacial polarizable molecules have slow dielectric relaxation but large polarization compared with the chitosan chains and water molecules,and the dielectric relaxations beyond~10^(4)Hz are substantially weak.The thermal activation energy of the dielectric relaxation for these interfacial polarizable molecules can be as large as 0.93 eV,i.e.89.73 kJ/mol.The present work provides a platform for characterizing the polymer-water electrostatic interactions and interfacial polarizable molecules,informative to understand the microstructure-property relationships of chitosan-based hydrogel materials.展开更多
基金supported by National Natural Science Foundation of China(no.U21A2047,no.51971076 and no.52001069).
文摘The deformation behavior of the as-extruded Mg-Y-Ni alloys with different volume fraction of long period stacking ordered(LPSO)phase during tension and compression was investigated by in-situ synchrotron diffraction.The micro-yielding,macro-yielding,tension-compression asymmetry and strain hardening behavior of the alloys were explored by combining with deformation mechanisms.The micro-yielding is dominated by basal slip of dynamic recrystallized(DRXed)grains in tension,while it is dominated by extension twinning of non-dynamic recrystallized(non-DRXed)grains in compression.At macro-yielding,the non-DRXed grains are still elastic deformed in tension and the basal slip of DRXed grains in compression are activated.Meanwhile,the LPSO phase still retains elastic deformation,but can bear more load,so the higher the volume fraction of hard LPSO phase,the higher the tensile/compressive macro-yield strength of the alloys.Benefiting from the low volume fraction of the non-DRXed grains and the delay effect of LPSO andγphases on extension twinning,the as-extruded alloys exhibit excellent tension-compression symmetry.When the volume fraction of LPSO phase reaches∼50%,tension-compression asymmetry is reversed,which is due to the fact that the LPSO phase is stronger in compression than in tension.The tensile strain hardening behavior is dominated by dislocation slip,while the dominate mechanism for compressive strain hardening changes from twinning in theα-Mg grains to kinking of the LPSO phase with increasing volume fraction of LPSO phase.The activation of kinking leads to the constant compressive strain hardening rate of∼2500 MPa,which is significantly higher than the tensile strain hardening rate.
基金Supported by the National Natural Science Foundation of China (12405140, 12135004, 11961141004, U2032138, 12275369)the Natural Science Foundation of Gansu Province, China (24JRRA033)+4 种基金financial support from the STFCfunded by the Chinese Academy of Sciences President's International Fellowship Initiative (2020VMA0017)Supported by the U.S. Department of Energy, Office of Nuclear Physics, (DE-AC02-06CH11357, DE-FG02-94ER41041 (UNC), DE-FG02-97ER41033 (TUNL))supported by the Slovak Research and Development Agency (APVV-22-0282)Slovak Grant Agency VEGA (1/0019/25)。
文摘Delayed γ-ray spectroscopy of^(185)Au was studied at the Argonne Gas-Filled Analyzer.A new isomer at an excitation energy of 1504.2(4) keV with a half-life of 630(80) ns was identified via γ-γ coincidence analysis,decaying via a 294.8(3) keV transition.Based on Weisskopf estimates,the multipolarity of the 295 keV transition is assigned to be E1,M1,E2,or M2.Possible configurations for this new isomer are discussed based on configurationconstrained potential energy surface calculations.
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This work was financially supported from the National Key Research Program of China(Grant Nos.2016YFA0300101 and 2015CB654602)the National Natural Science Foundation of China(Grant Nos.51431006 and 51721001).
文摘The functionalities of hydrogel-based smart materials are highly related to the electrostatic interactions and molecular polarization associated with the polymer networks and encapsulated water droplets,and therefore the dielectric responses of the polarizable molecules in the polymer,water,and polymer-water interfaces are particularly attractive,where the properties of polymer-water interfacial molecules remain elusive.Different from extensive dielectric relaxation spectroscopy studies on polymer hydrogel solutions,in this work we investigate the dielectric response of chitosan hydrogels below the water solidifying point(ice-hydrogels)so that the contribution of chitosan-water interfacial molecules can be isolated.It is revealed that the chitosan-water interfacial polarizable molecules have slow dielectric relaxation but large polarization compared with the chitosan chains and water molecules,and the dielectric relaxations beyond~10^(4)Hz are substantially weak.The thermal activation energy of the dielectric relaxation for these interfacial polarizable molecules can be as large as 0.93 eV,i.e.89.73 kJ/mol.The present work provides a platform for characterizing the polymer-water electrostatic interactions and interfacial polarizable molecules,informative to understand the microstructure-property relationships of chitosan-based hydrogel materials.
