Obtaining an electrocorticograms(ECoG)signal requires an invasive procedure in which brain activity is recorded from the cortical surface.In contrast,obtaining electroencephalograms(EEG)recordings requires the non-inv...Obtaining an electrocorticograms(ECoG)signal requires an invasive procedure in which brain activity is recorded from the cortical surface.In contrast,obtaining electroencephalograms(EEG)recordings requires the non-invasive procedure of recording the brain activity from the scalp surface,which allows EEG recordings to be performed more easily on healthy humans.In this work,a technique previously used to study spatial-temporal patterns of brain activity on animal ECoG was adapted for use on EEG.The main issues are centered on solving the problems introduced by the increment on the interelectrode distance and the procedure to detect stable frames.The results showed that spatial patterns of beta and gamma activity can also be extracted from the EEG signal by using stable frames as time markers for feature extraction.This adapted technique makes it possible to take advantage of the cognitive and phenomenological awareness of a normal healthy subject.展开更多
Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised Z...Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised ZnO. ZnO is thermodynamically stable up to 300GPa and zinc peroxide （Zn02, space group Pa3） is metastable under lower pressure. Insulating I4/mcm-Zn02 is thermodynamically stable between 128.3-300 GPa. Insulated metastable P3121-Zn02, controlling the pressure range of 51.5-128.3 GPa, has a wide band gap compared to the Pa3-Zn02 and I4/mem-Zn02. Phonon and elastic constant calculations conclude the dynamical and mechanical stability for the explored thermodynamically stable or metastable structures.展开更多
1 Introduction Salt lakes are widely distributed in the world,and salt lakes in China are mainly located in the area of the Qinghai-Xizang(Tibet),and the Autonomous Regions of Xinjiang and Inner Mongolia.There are mor...1 Introduction Salt lakes are widely distributed in the world,and salt lakes in China are mainly located in the area of the Qinghai-Xizang(Tibet),and the Autonomous Regions of Xinjiang and Inner Mongolia.There are more than 700salt lakes,each with an area larger than 1 km2,in the展开更多
Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase ...Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase to BCC phase with the increase of Al content.The stable phase of FeCoNiCrCu0.5Alx high-entropy alloys will transform from FCC phase to FCC＋BCC duplex phases when x value increases from 0.5 to 1.5.The hardness of BCC phase is higher than that of FCC phase,and the corrosion resistance of BCC phase is better than FCC phase in chlorine ion and acid medium.High hardness and good corrosion resistance can be obtained in as-cast FeCoNiCrCu0.5Al1.0 alloy.展开更多
Doping is critical for inducing ferroelectricity in hafnia films,yet the underlying mechanisms remain debated.Here,through first-principles studies,we elucidate the pivotal role played by the complex phase transition ...Doping is critical for inducing ferroelectricity in hafnia films,yet the underlying mechanisms remain debated.Here,through first-principles studies,we elucidate the pivotal role played by the complex phase transition mechanisms under carrier doping in understanding the origin of hafnia ferroelectricity.Specifically,electron doping orchestrates a metastable polar phase to stable antipolar phase transformation,driven by strong screening effects and weakened nonpolar covalent bonds,making n-type dopants rare.Conversely,weak screening effect and enhanced polar covalent bonding strengthen robust ferroelectricity,enabling significant ground-state phase transitions from the monoclinic to the polar orthorhombic phase and finally to the cubic phase under hole doping,a phenomenon prevalent in hafnia-based films doped with p-type dopants.Furthermore,this holeenhanced polar distortion also results in an inverse size effect in hafnia ferroelectric films,unlike perovskite ferroelectrics.Our findings offer new insights into the preparation of robust hafnia-based ferroelectric films through doping or interface engineering.展开更多
The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model. It is found that with the balance between pondermotive forc...The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model. It is found that with the balance between pondermotive force and electrostatic force, highly quasi-monoenergetic proton beam can be generated by Phase Stable Acceleration (PSA) process. As in conventional accelerators, ion will be accelerated and bunched up in the longitudinal direction at the same time.展开更多
基金supported by the National Natural Science Foundation of China(Nos.60421002 and 60874098)the National High-Tech Research and Development Program(863)of China(No.2007AA042103)
文摘Obtaining an electrocorticograms(ECoG)signal requires an invasive procedure in which brain activity is recorded from the cortical surface.In contrast,obtaining electroencephalograms(EEG)recordings requires the non-invasive procedure of recording the brain activity from the scalp surface,which allows EEG recordings to be performed more easily on healthy humans.In this work,a technique previously used to study spatial-temporal patterns of brain activity on animal ECoG was adapted for use on EEG.The main issues are centered on solving the problems introduced by the increment on the interelectrode distance and the procedure to detect stable frames.The results showed that spatial patterns of beta and gamma activity can also be extracted from the EEG signal by using stable frames as time markers for feature extraction.This adapted technique makes it possible to take advantage of the cognitive and phenomenological awareness of a normal healthy subject.
基金Supported by the National Natural Science Foundation of China under Grant No 11347007the Qing Lan Project+1 种基金the Colleges and Universities in Jiangsu Province Natural Science Research Project under Grant No 14KJB460013the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Variable-composition evolutionary structure searches are used to explore stable stoichiometries for the Zn-O system below 300 GPa. Our results confirm the previous structural phase transition sequence of pressurised ZnO. ZnO is thermodynamically stable up to 300GPa and zinc peroxide （Zn02, space group Pa3） is metastable under lower pressure. Insulating I4/mcm-Zn02 is thermodynamically stable between 128.3-300 GPa. Insulated metastable P3121-Zn02, controlling the pressure range of 51.5-128.3 GPa, has a wide band gap compared to the Pa3-Zn02 and I4/mem-Zn02. Phonon and elastic constant calculations conclude the dynamical and mechanical stability for the explored thermodynamically stable or metastable structures.
基金Financial support from the State Key Program of NNSFC (20836009)the NNSFCs (Grants 21106136, 21276194 and 21306136)
文摘1 Introduction Salt lakes are widely distributed in the world,and salt lakes in China are mainly located in the area of the Qinghai-Xizang(Tibet),and the Autonomous Regions of Xinjiang and Inner Mongolia.There are more than 700salt lakes,each with an area larger than 1 km2,in the
基金Project(NCET-11-0127) supported by the Program for New Century Excellent Talents in University,ChinaProject supported by the Fundamental Research Funds for the Central Universities,China
文摘Effects of Al content and heat treatment on the structure,hardness and electrochemical properties of FeCoNiCrCu0.5Alx high-entropy alloys were investigated.The phase structure of as-cast alloys evolves from FCC phase to BCC phase with the increase of Al content.The stable phase of FeCoNiCrCu0.5Alx high-entropy alloys will transform from FCC phase to FCC＋BCC duplex phases when x value increases from 0.5 to 1.5.The hardness of BCC phase is higher than that of FCC phase,and the corrosion resistance of BCC phase is better than FCC phase in chlorine ion and acid medium.High hardness and good corrosion resistance can be obtained in as-cast FeCoNiCrCu0.5Al1.0 alloy.
基金supported by financial support from the National Natural Science Foundation of China(Grant Nos.92164108 and U23A20322,51971188,51471139)the National Key Research and Development Program of China(2023YFF0719600)+4 种基金Hunan Provincial Natural Science Foundation(Grant Nos.2023JJ50009 and 2023JJ30599)the Guangdong Provincial Key Laboratory Program from the Department of Science and Technology of Guangdong Province(2021B1212040001)the Outstanding Youth Science Foundation of Hunan Province,China(Grant No.2021JJ20041)the Key Project of Scientific Research Fund of Hunan Provincial Education Department(Grant No.23A0150)the Chongqing Municipal Education Commission Science and Technology Research Program Youth Project(KJQN202101423).
文摘Doping is critical for inducing ferroelectricity in hafnia films,yet the underlying mechanisms remain debated.Here,through first-principles studies,we elucidate the pivotal role played by the complex phase transition mechanisms under carrier doping in understanding the origin of hafnia ferroelectricity.Specifically,electron doping orchestrates a metastable polar phase to stable antipolar phase transformation,driven by strong screening effects and weakened nonpolar covalent bonds,making n-type dopants rare.Conversely,weak screening effect and enhanced polar covalent bonding strengthen robust ferroelectricity,enabling significant ground-state phase transitions from the monoclinic to the polar orthorhombic phase and finally to the cubic phase under hole doping,a phenomenon prevalent in hafnia-based films doped with p-type dopants.Furthermore,this holeenhanced polar distortion also results in an inverse size effect in hafnia ferroelectric films,unlike perovskite ferroelectrics.Our findings offer new insights into the preparation of robust hafnia-based ferroelectric films through doping or interface engineering.
基金Supported by NSFC (10855001, 10674175, 60621063)National High-Tech ICF Committee
文摘The interaction of ultrashort intense circularly polarized laser with ultra thin overdense foil is studied by particle-in-cell simulation and analytic model. It is found that with the balance between pondermotive force and electrostatic force, highly quasi-monoenergetic proton beam can be generated by Phase Stable Acceleration (PSA) process. As in conventional accelerators, ion will be accelerated and bunched up in the longitudinal direction at the same time.
