A detector for fast neutrons based on a 10 × 10 cm^2 triple gas electron multiplier （GEM） device is developed and tested. A neutron converter, which is a high density polyethylene （HDPE） layer, is combined wi...A detector for fast neutrons based on a 10 × 10 cm^2 triple gas electron multiplier （GEM） device is developed and tested. A neutron converter, which is a high density polyethylene （HDPE） layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics （IMP） at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium （DT, 14 MeV）, deuterium-deuterium （DD, 2.45 MeV）, and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton （GEM material）, and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented.展开更多
Laparoscopic liver resection （LLR） for hepatocellular carcinoma （HCC） is increasing in this era of minimal invasive liver surgery. LLR for HCC is currently known to be a safer procedure than it was before because ...Laparoscopic liver resection （LLR） for hepatocellular carcinoma （HCC） is increasing in this era of minimal invasive liver surgery. LLR for HCC is currently known to be a safer procedure than it was before because of technical advances and improvement in postoperative patient management and remains the first-line treatment for HCC in compensated cirrhosis in many centers. We have the chance of analyzing the paper about the comparison between Middle Eastern and Western experience for LLR as treatment of HCC.展开更多
This study evaluates the performance of polymer fire-retardant and extinguishing gels through experimental comparisons with traditional foam extinguishing agents and water.The findings indicate that polymer fire-retar...This study evaluates the performance of polymer fire-retardant and extinguishing gels through experimental comparisons with traditional foam extinguishing agents and water.The findings indicate that polymer fire-retardant and extinguishing gels exhibit significant advantages over conventional water and foam in terms of fire suppression and prevention of re-ignition.Based on these results,the fire retardant mechanisms of the polymer gel are hypothesized.展开更多
We conduct a systematic investigation of the role of Hubbard U corrections in electronic structure calculations of two-dimensional(2D)materials containing 3d transition metals.Specifically,we use density functional th...We conduct a systematic investigation of the role of Hubbard U corrections in electronic structure calculations of two-dimensional(2D)materials containing 3d transition metals.Specifically,we use density functional theory(DFT)with the PBE and PBE+U approximations to calculate the crystal structure,band gaps,and magnetic parameters of 638 monolayers.Based on a comprehensive comparison to experiments we first establish that the inclusion of the U correction worsens the accuracy for the lattice constants.Consequently,PBE structures are used for subsequent property evaluations.The band gaps show a significant dependence on U.In particular,for 134(21%)of the materials the U parameter induces a metal-to-insulator transition.For the magnetic materials we calculate the magnetic moment,magnetic exchange coupling,and magnetic anisotropy parameters.In contrast to the band gaps,the size of the magnetic moments shows only weak dependence on U.Both the exchange energies and magnetic anisotropy parameters are systematically reduced by theU correction.On this basis we conclude that the Hubbard U correction will lead to lower predicted Curie temperatures in 2D materials.All the calculated properties are available in the Computational 2D Materials Database(C2DB).展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11135002,11305232 and 11175076the Foundation of China Spallation Neutron Source:Study and Development of the High-performance and Low-angle Detector
文摘A detector for fast neutrons based on a 10 × 10 cm^2 triple gas electron multiplier （GEM） device is developed and tested. A neutron converter, which is a high density polyethylene （HDPE） layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics （IMP） at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium （DT, 14 MeV）, deuterium-deuterium （DD, 2.45 MeV）, and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton （GEM material）, and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented.
文摘Laparoscopic liver resection （LLR） for hepatocellular carcinoma （HCC） is increasing in this era of minimal invasive liver surgery. LLR for HCC is currently known to be a safer procedure than it was before because of technical advances and improvement in postoperative patient management and remains the first-line treatment for HCC in compensated cirrhosis in many centers. We have the chance of analyzing the paper about the comparison between Middle Eastern and Western experience for LLR as treatment of HCC.
基金Supported by Central Finance Forestry Science and Technology Promotion Demonstration Project(H[2023]TG31).
文摘This study evaluates the performance of polymer fire-retardant and extinguishing gels through experimental comparisons with traditional foam extinguishing agents and water.The findings indicate that polymer fire-retardant and extinguishing gels exhibit significant advantages over conventional water and foam in terms of fire suppression and prevention of re-ignition.Based on these results,the fire retardant mechanisms of the polymer gel are hypothesized.
基金the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation programme Grant No.773122(LIMA)and Grant agreement No.951786(NOMAD CoE)A high-performance computing infrastructure for data-driven research on sustainable energy materials,Grant no.NNF22OC0078009.K.S.T.is a Villum Investigator supported by VILLUM FONDEN(grant no.37789).
文摘We conduct a systematic investigation of the role of Hubbard U corrections in electronic structure calculations of two-dimensional(2D)materials containing 3d transition metals.Specifically,we use density functional theory(DFT)with the PBE and PBE+U approximations to calculate the crystal structure,band gaps,and magnetic parameters of 638 monolayers.Based on a comprehensive comparison to experiments we first establish that the inclusion of the U correction worsens the accuracy for the lattice constants.Consequently,PBE structures are used for subsequent property evaluations.The band gaps show a significant dependence on U.In particular,for 134(21%)of the materials the U parameter induces a metal-to-insulator transition.For the magnetic materials we calculate the magnetic moment,magnetic exchange coupling,and magnetic anisotropy parameters.In contrast to the band gaps,the size of the magnetic moments shows only weak dependence on U.Both the exchange energies and magnetic anisotropy parameters are systematically reduced by theU correction.On this basis we conclude that the Hubbard U correction will lead to lower predicted Curie temperatures in 2D materials.All the calculated properties are available in the Computational 2D Materials Database(C2DB).
