Tidal fluctuations of Hangzhou Bay produce progressive pressure waves in adjacent field fractured aquifers, as the pressure waves propagate, groundwater levels and hydraulic gradients continuously fluctuate. The effec...Tidal fluctuations of Hangzhou Bay produce progressive pressure waves in adjacent field fractured aquifers, as the pressure waves propagate, groundwater levels and hydraulic gradients continuously fluctuate. The effect of tidal fluctuations on groundwater flow can be determined using the mean hydraulic gradient that can be calculated by comparing mean ground and surface water elevations.Tidal fluctuation is shown to affect the piezometer readings taken in a nearshore fractured aquifer around the nuclear power engineering field. Continuous monitoring of a network of seven piezometers provided relations between the tidal cycle and the piezometer readings. The relations can be expressed in times of a time and amplitude scaling factor. The time lag and the tidal efficiency factor and wavelength are calculated using these parameters. It provides significant scientific basis to prevent tide and groundwater for the nuclear power engineering construction and safety run of nuclear power station in the future.展开更多
After World War II,the choice of the plutonium bomb as the technology roadmap for the first French atomic bomb was not a military issue,but rather one guided by civilian nuclear technology policy.After consideration o...After World War II,the choice of the plutonium bomb as the technology roadmap for the first French atomic bomb was not a military issue,but rather one guided by civilian nuclear technology policy.After consideration of the amount of uranium to be mined,technical reserves,and the financial situation,the civilian nuclear energy project of the Commissariatàl’énergie Atomique(CEA)was based on plutonium and natural uranium as the fissile materials,which indirectly provided enough plutonium for the future development of a nuclear weapon.When the Fourth Republic decided to develop the atomic bomb,a“Common Core”was established with the CEA,a public institution,as the lead,assisted by the military.Faced by the US embargo of nuclear weapons technology,the co-existence of civilian and military branches and their collaboration to some degree in the CEA not only made it a civilian-military complex,but also facilitated breakthroughs in the core technologies of implosion,the plutonium core,the tamper,and the neutron source.The success of the first French nuclear weapons test on February 13,1960,announced that France was on its way to becoming self-reliant in the military use of nuclear science.展开更多
The magnesium has some excellent properties such as ligh quality, high specific strength and stiffness, high damp and reeoverd easily compared with steel, aluminium, engineering plastic. So the application and exploit...The magnesium has some excellent properties such as ligh quality, high specific strength and stiffness, high damp and reeoverd easily compared with steel, aluminium, engineering plastic. So the application and exploitation of magnesium arose extensive attention of the public.展开更多
Confined low dimensional charges with high density such as two-dimensional electron gas(2 DEG)at interfaces and charged domain walls in ferroelectrics show great potential to serve as functional elements in future nan...Confined low dimensional charges with high density such as two-dimensional electron gas(2 DEG)at interfaces and charged domain walls in ferroelectrics show great potential to serve as functional elements in future nanoelectronics.However,stabilization and control of low dimensional charges is challenging,as they are usually subject to enormous depolarization fields.Here,we demonstrate a method to fabricate tunable charged interfaces with~77°,86°and 94°head-to-head polarization configurations in multiferroic Bi Fe O_(3) thin films by grain boundary engineering.The adjacent grains are cohesively bonded and the boundary is about 1 nm in width and devoid of any amorphous region.Remarkably,the polarization remains almost unchanged near the grain boundaries,indicating the polarization charges are well compensated,i.e.,there should be two-dimensional charge gas confined at grain boundaries.Adjusting the tilt angle of the grain boundaries enables tuning the angle of polarization configurations from 71°to 109°,which in turn allows the control of charge density at the grain boundaries.This general and feasible method opens new doors for the application of charged interfaces in next generation nanoelectronics.展开更多
Electronic regulation of two-dimensional(2 D)transition metal dichalcogenides(TMDCs)is a crucial step towards next-generation optoelectronics and electronics.Here,we demonstrate controllable and selective-area defect ...Electronic regulation of two-dimensional(2 D)transition metal dichalcogenides(TMDCs)is a crucial step towards next-generation optoelectronics and electronics.Here,we demonstrate controllable and selective-area defect engineering in 2D molybdenum disulfide(MoS_(2))using a focused ion beam with a low-energy gallium ion(Ga^(+))source.We find that the surface defects of MoS_(2)can be tuned by the precise control of ion energy and dose.Furthermore,the fieldeffect transistors based on the monolayer MoS_(2)show a significant threshold voltage modulation over 70 V after Ga+irradiation.First-principles calculations reveal that the Ga impurities in the monolayer MoS_(2)introduce a defect state near the Fermi level,leading to a shallow acceptor level of 0.25 eV above the valence band maximum.This defect engineering strategy enables direct writing of complex pattern at the atomic length scale in a controlled and facile manner,tailoring the electronic properties of 2D TMDCs for novel devices.展开更多
文摘Tidal fluctuations of Hangzhou Bay produce progressive pressure waves in adjacent field fractured aquifers, as the pressure waves propagate, groundwater levels and hydraulic gradients continuously fluctuate. The effect of tidal fluctuations on groundwater flow can be determined using the mean hydraulic gradient that can be calculated by comparing mean ground and surface water elevations.Tidal fluctuation is shown to affect the piezometer readings taken in a nearshore fractured aquifer around the nuclear power engineering field. Continuous monitoring of a network of seven piezometers provided relations between the tidal cycle and the piezometer readings. The relations can be expressed in times of a time and amplitude scaling factor. The time lag and the tidal efficiency factor and wavelength are calculated using these parameters. It provides significant scientific basis to prevent tide and groundwater for the nuclear power engineering construction and safety run of nuclear power station in the future.
基金a phase study of a key project of the Fourteenth Five-Year Plan of the Institute for the History of Natural Sciences,Chinese Academy of Sciences:“A Comparative Study of the Sino-Foreign History of Scientific and Technological Innovation:The Road to Scientific and Technological Self-Reliance and Self-Improvement”(中外科技创新史比较研究——科技自立自强之路)(E2291J01)
文摘After World War II,the choice of the plutonium bomb as the technology roadmap for the first French atomic bomb was not a military issue,but rather one guided by civilian nuclear technology policy.After consideration of the amount of uranium to be mined,technical reserves,and the financial situation,the civilian nuclear energy project of the Commissariatàl’énergie Atomique(CEA)was based on plutonium and natural uranium as the fissile materials,which indirectly provided enough plutonium for the future development of a nuclear weapon.When the Fourth Republic decided to develop the atomic bomb,a“Common Core”was established with the CEA,a public institution,as the lead,assisted by the military.Faced by the US embargo of nuclear weapons technology,the co-existence of civilian and military branches and their collaboration to some degree in the CEA not only made it a civilian-military complex,but also facilitated breakthroughs in the core technologies of implosion,the plutonium core,the tamper,and the neutron source.The success of the first French nuclear weapons test on February 13,1960,announced that France was on its way to becoming self-reliant in the military use of nuclear science.
文摘The magnesium has some excellent properties such as ligh quality, high specific strength and stiffness, high damp and reeoverd easily compared with steel, aluminium, engineering plastic. So the application and exploitation of magnesium arose extensive attention of the public.
基金supported by the National Basic Research Program of China(2016YFA0300804)the National Natural Science Foundation of China(51672007 and 11974023)+6 种基金Key Area R&D Program of Guangdong Province(2018B010109009)the Key R&D Program of Guangdong Province(2018B030327001)National Equipment Program of China(ZDYZ2015-1)the‘‘2011 Program”Peking-Tsinghua-IOP Collaborative Innovation Centre for Quantum Mattersupported by the National Basic Research Program of China(2016YFA0301004)the National Natural Science Foundation of China(51872155,52025024)the Beijing Advanced Innovation Center for Future Chip(ICFC)。
文摘Confined low dimensional charges with high density such as two-dimensional electron gas(2 DEG)at interfaces and charged domain walls in ferroelectrics show great potential to serve as functional elements in future nanoelectronics.However,stabilization and control of low dimensional charges is challenging,as they are usually subject to enormous depolarization fields.Here,we demonstrate a method to fabricate tunable charged interfaces with~77°,86°and 94°head-to-head polarization configurations in multiferroic Bi Fe O_(3) thin films by grain boundary engineering.The adjacent grains are cohesively bonded and the boundary is about 1 nm in width and devoid of any amorphous region.Remarkably,the polarization remains almost unchanged near the grain boundaries,indicating the polarization charges are well compensated,i.e.,there should be two-dimensional charge gas confined at grain boundaries.Adjusting the tilt angle of the grain boundaries enables tuning the angle of polarization configurations from 71°to 109°,which in turn allows the control of charge density at the grain boundaries.This general and feasible method opens new doors for the application of charged interfaces in next generation nanoelectronics.
基金supported by Fujian Minjiang Distinguished Scholar Programthe Department of Science and Technology of Fujian Province(2020J01704 and 2019L3008)the Scientific Research Foundation from Jimei University(ZP2020066 and ZP2020065)。
文摘Electronic regulation of two-dimensional(2 D)transition metal dichalcogenides(TMDCs)is a crucial step towards next-generation optoelectronics and electronics.Here,we demonstrate controllable and selective-area defect engineering in 2D molybdenum disulfide(MoS_(2))using a focused ion beam with a low-energy gallium ion(Ga^(+))source.We find that the surface defects of MoS_(2)can be tuned by the precise control of ion energy and dose.Furthermore,the fieldeffect transistors based on the monolayer MoS_(2)show a significant threshold voltage modulation over 70 V after Ga+irradiation.First-principles calculations reveal that the Ga impurities in the monolayer MoS_(2)introduce a defect state near the Fermi level,leading to a shallow acceptor level of 0.25 eV above the valence band maximum.This defect engineering strategy enables direct writing of complex pattern at the atomic length scale in a controlled and facile manner,tailoring the electronic properties of 2D TMDCs for novel devices.
