The effect of Zr doping in Ni 3Al and B doping in Co 3Ti intermetallics on the sensitivity to moisture induced environmental embrittlement and on the hydrogen diffusivity was investigated. The results show that both B...The effect of Zr doping in Ni 3Al and B doping in Co 3Ti intermetallics on the sensitivity to moisture induced environmental embrittlement and on the hydrogen diffusivity was investigated. The results show that both B in Co 3Ti and Zr in Ni 3Al do not reduce the hydrogen diffusivity along the grain boundaries, therefore can not suppress the moisture induced environmental embrittlement. The above mentioned behavior of Zr in Ni 3Al and B in Co 3Ti is attributed to the fact that Zr and B are not segregated on the grain boundaries.展开更多
Micro-sized（1030.3±178.4 nm） and nano-sized（50.4±8.0 nm） Fe3O4 particles have been fabricated through hydrogen thermal reduction of α-Fe2O3 particles synthesized by means of a hydrothermal process.The m...Micro-sized（1030.3±178.4 nm） and nano-sized（50.4±8.0 nm） Fe3O4 particles have been fabricated through hydrogen thermal reduction of α-Fe2O3 particles synthesized by means of a hydrothermal process.The morphology and microstructure of the micro-sized and the nano-sized Fe3O4 particles were characterized by X-ray diffraction,field-emission gun scanning electron microscopy,transmission electron microscopy and highresolution electron microscopy.The micro-sized Fe3O4 particles exhibit porous structure,while the nano-sized Fe3O4 particles are solid structure.Their electrochemical performance was also evaluated.The nano-sized solid Fe3O4 particles exhibit gradual capacity fading with initial discharge capacity of 1083.1 mAhg-1 and reversible capacity retention of 32.6% over 50 cycles.Interestingly,the micro-sized porous Fe3O4 particles display very stable capacity-cycling behavior,with initial discharge capacity of 887.5 mAhg-1 and charge capacity of 684.4 mAhg-1 at the 50th cycle.Therefore,77.1% of the reversible capacity can be maintained over 50 cycles.The micro-sized porous Fe3O4 particles with facile synthesis,good cycling performance and high capacity retention are promising candidate as anode materials for high energy-density lithium-ion batteries.展开更多
The establishment of a possible connection between neutrino emission and gravitational-wave(GW)bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge.In t...The establishment of a possible connection between neutrino emission and gravitational-wave(GW)bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge.In the Daya Bay experiment,using the data collected from December 2011 to August 2017,a search was per-formed for electron-antineutrino signals that coincided with detected GW events,including GW150914,GW151012,GW151226,GW170104,GW170608,GW 170814,and GW 170817.We used three time windows of±10,±500,and±1000 s relative to the occurrence of the GW events and a neutrino energy range of 1.8 to 100 MeV to search for correlated neutrino candidates.The detected electron-antineutrino candidates were consistent with the expected background rates for all the three time windows.Assuming monochromatic spectra,we found upper limits(90%confidence level)of the electron-antineutrino fluence of(1.13-2.44)×10^(11)cm^(-2)at 5 MeV to 8.0×10^(7)cm^(-2)at 100 MeV for the three time w indows.Under the assumption of a Fermi-Dirac spectrum,the upper limits were found to be(5.4-7.0)×10^(9)cm^(2)for the three time windows.展开更多
The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by ...The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2%precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.展开更多
The surface reaction of Co 3Ti alloys (with and without Fe) with water vapor was investigated by using Auger electron spectroscopy (AES). The results showed that the rate of the surface reaction is much lower in Co 21...The surface reaction of Co 3Ti alloys (with and without Fe) with water vapor was investigated by using Auger electron spectroscopy (AES). The results showed that the rate of the surface reaction is much lower in Co 21 5Ti 3Fe alloy as compared with Co 3Ti (Co 23Ti) alloy. The surface reaction of Co 21 5Ti 3Fe alloy with water vapor saturates at exposure of 2×10 -3 Pa·s, but it does not saturate even at 0 1 Pa·s exposure for Co 3Ti alloy without Fe. The results also indicated that the kinetic of the surface reaction of Co 21 5Ti 3Fe with water vapor is much smaller than that of Co 3Ti at the same exposure. All the above results illustrate that the suppression of environmental embrittlement by addition of Fe to Co 3Ti alloy is attributed to its reduction of the surface reaction kinetics with water vapor.展开更多
文摘The effect of Zr doping in Ni 3Al and B doping in Co 3Ti intermetallics on the sensitivity to moisture induced environmental embrittlement and on the hydrogen diffusivity was investigated. The results show that both B in Co 3Ti and Zr in Ni 3Al do not reduce the hydrogen diffusivity along the grain boundaries, therefore can not suppress the moisture induced environmental embrittlement. The above mentioned behavior of Zr in Ni 3Al and B in Co 3Ti is attributed to the fact that Zr and B are not segregated on the grain boundaries.
基金supported by the National Natural Science Foundation of China (Grand No. 50872032)the financial support from the Hundred Talents Program of the Chinese Academy of Sciencesthe National Basic Research Program of China(Grant No. 2010CB631006)
文摘Micro-sized（1030.3±178.4 nm） and nano-sized（50.4±8.0 nm） Fe3O4 particles have been fabricated through hydrogen thermal reduction of α-Fe2O3 particles synthesized by means of a hydrothermal process.The morphology and microstructure of the micro-sized and the nano-sized Fe3O4 particles were characterized by X-ray diffraction,field-emission gun scanning electron microscopy,transmission electron microscopy and highresolution electron microscopy.The micro-sized Fe3O4 particles exhibit porous structure,while the nano-sized Fe3O4 particles are solid structure.Their electrochemical performance was also evaluated.The nano-sized solid Fe3O4 particles exhibit gradual capacity fading with initial discharge capacity of 1083.1 mAhg-1 and reversible capacity retention of 32.6% over 50 cycles.Interestingly,the micro-sized porous Fe3O4 particles display very stable capacity-cycling behavior,with initial discharge capacity of 887.5 mAhg-1 and charge capacity of 684.4 mAhg-1 at the 50th cycle.Therefore,77.1% of the reversible capacity can be maintained over 50 cycles.The micro-sized porous Fe3O4 particles with facile synthesis,good cycling performance and high capacity retention are promising candidate as anode materials for high energy-density lithium-ion batteries.
基金Daya Bay is supported in part by the Ministry of Science and Technology o f China, the U.S. Department o f Energy, the Chinese Academy of Sciences, the CASCenter for Excellence in Particle Physics, the National Natural Science Foundation of China, the Guangdong provincial government, the Shenzhen municipal government,the China General Nuclear Power Group, Key Laboratory of Particle and Radiation Imaging (Tsinghua University), the Ministry of Education, Key Laboratory ofParticle Physics and Particle Irradiation (Shandong University), the Ministry o f Education, Shanghai Laboratory for Particle Physics and Cosmology, the ResearchGrants Council o f the Hong Kong Special Administrative Region of China, the University Development Fund of the University of Hong Kong, the MOE program forResearch of Excellence at National Taiwan University, National Chiao-Tung University, NSC fund support from Taiwan, the U.S. National Science Foundation, the AlfredP. Sloan Foundation, the Ministry o f Education, Youth, and Sports of the Czech Republic, the Charles University GAUK (284317), the Joint Institute o f NuclearResearch in Dubna, Russia, the National Commission of Scientific and Technological Research of Chile, and the Tsinghua University Initiative Scientific Research Program.
文摘The establishment of a possible connection between neutrino emission and gravitational-wave(GW)bursts is important to our understanding of the physical processes that occur when black holes or neutron stars merge.In the Daya Bay experiment,using the data collected from December 2011 to August 2017,a search was per-formed for electron-antineutrino signals that coincided with detected GW events,including GW150914,GW151012,GW151226,GW170104,GW170608,GW 170814,and GW 170817.We used three time windows of±10,±500,and±1000 s relative to the occurrence of the GW events and a neutrino energy range of 1.8 to 100 MeV to search for correlated neutrino candidates.The detected electron-antineutrino candidates were consistent with the expected background rates for all the three time windows.Assuming monochromatic spectra,we found upper limits(90%confidence level)of the electron-antineutrino fluence of(1.13-2.44)×10^(11)cm^(-2)at 5 MeV to 8.0×10^(7)cm^(-2)at 100 MeV for the three time w indows.Under the assumption of a Fermi-Dirac spectrum,the upper limits were found to be(5.4-7.0)×10^(9)cm^(2)for the three time windows.
基金Supported in part by the Ministry of Science and Technology of Chinathe U.S.Department of Energy,the Chinese Academy of Sciences,the CAS Center for Excellence in Particle Physics,the National Natural Science Foundation of China+3 种基金the Guangdong provincial governmentthe Shenzhen municipal government,the China General Nuclear Power Group,the Research Grants Council of the Hong Kong Special Administrative Region of China,the Ministry of Education in TWthe U.S.National Science Foundation,the Ministry of Education,Youth,and Sports of the Czech Republic,the Charles University Research Centre UNCE,the Joint Institute of Nuclear Research in Dubna,Russiathe National Commission of Scientific and Technological Research of Chile。
文摘The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era.The positron energy spectrum of 3.5 million antineutrino inverse beta decay reactions observed by the Daya Bay experiment,in combination with the fission rates of fissile isotopes in the reactor,is used to extract the positron energy spectra resulting from the fission of specific isotopes.This information can be used to produce a precise,data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay.The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method.Consistent results are obtained with other unfolding methods.A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated.Given the reactor fission fractions,the technique can predict the energy spectrum to a 2%precision.In addition,we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.
文摘The surface reaction of Co 3Ti alloys (with and without Fe) with water vapor was investigated by using Auger electron spectroscopy (AES). The results showed that the rate of the surface reaction is much lower in Co 21 5Ti 3Fe alloy as compared with Co 3Ti (Co 23Ti) alloy. The surface reaction of Co 21 5Ti 3Fe alloy with water vapor saturates at exposure of 2×10 -3 Pa·s, but it does not saturate even at 0 1 Pa·s exposure for Co 3Ti alloy without Fe. The results also indicated that the kinetic of the surface reaction of Co 21 5Ti 3Fe with water vapor is much smaller than that of Co 3Ti at the same exposure. All the above results illustrate that the suppression of environmental embrittlement by addition of Fe to Co 3Ti alloy is attributed to its reduction of the surface reaction kinetics with water vapor.
