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Spatiotemporal evolution of wildfire activity during the PaleoceneEocene Thermal Maximum in China

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Science China Earth Sciences 2025年

作者： Xueting WANG Zuoling CHEN Linlin CUI Xu WANG State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences College of Earth and Planetary Sciences Institute of Geology and Geophysics Chinese Academy of Sciences

The Paleocene-Eocene Thermal Maximum（PETM） was the most prominent warming event in the Cenozoic and serves as a geological analog for the current global warming driven by anthropogenic CO2emissions from burning fossil *** a primary disruptor of Earth's ecosystems, wildfire activity affects the balance of ecosystems, the global carbon cycle, and climate change. Therefore, studying the evolution and driving mechanisms of wildfires during the PETM is essential for predicting wildfire activity under global warming scenarios and for understanding the carbon cycle in the context of wildfire disturbances. Current research on wildfires during the PETM has mainly focused on the Northern Hemisphere, particularly Europe and North America, whereas studies on Chinese mainland remain limited. In this study, we analyzed black carbon（BC）concentration and carbon isotope(δ13C) in the Beigou section of the Nanyang Basin and the Xilutian section of the Fushun Basin to reconstruct the spatiotemporal evolution of wildfires in arid/semi-arid and humid zones. We integrated these findings with those of previous studies on the paleoclimate of the research area to elucidate the driving mechanisms behind wildfire occurrences. Our results indicate that wildfire activity weakened at the onset of the PETM, with the negative carbon isotope period characterized by low wildfire activity, except for a brief resurgence in the Nanyang Basin. During the recovery phase of the PETM, wildfire activity gradually increased, returning to the pre-PETM levels. The prolonged low wildfire state was likely caused by extremely high temperatures and precipitation as well as the resulting vegetation succession. During the PETM recovery phase, increased wildfire activity transformed “short-term carbon sinks” of the biological-atmospheric carbon cycle into “long-term carbon sinks” through the burial of BC. This process of carbon sink conversion may have acted as a negative feedback mechanism, contributing to carbo

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Effects of mesoscale gravity waves on sporadic E simulated by a one-dimensional dynamic model

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Earth and Planetary Physics 2025年第1期9卷 1-9页

作者： Xu Zhou ZeZhong Li XinAn Yue LiBo Liu Key Laboratory of Earth and Planetary Physics/Heilongjiang Mohe National Geophysical Observatory/Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences(CAS)Beijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China cas Center for Excellence in Comparative Planetology/cas Key Laboratory of Geospace Environment/Mengcheng National Geophysical Observatory University of Science and Technology of ChinaHefei 230026China

In addition to being driven by tidal winds,the sporadic E(Es)layers are modulated by gravity waves(GWs),although the effects are not yet comprehensively *** this article,we discuss the effects of mesoscale GWs on the Es layers determined by using a newly developed model,MISE-1D(one-dimensional Model of Ionospheric Sporadic E),with low numerical dissipation and high *** by the wind fields resolved by the high-resolution version of the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension(WACCM-X),the MISE-1D simulation revealed that GWs significantly influence the evolution of the Es layer above 100 km but have a very limited effect at lower *** effects of GWs are diverse and complex,generally including the generation of fluctuating wavelike structures on the Es layer with frequencies similar to those of the *** mesoscale GWs can also cause increases in the density of Es layers,or they can disperse or diffuse the Es layers and increase their *** addition,the presence of GWs is a key factor in sustaining the Es layers in some cases.

关键词： sporadic E ion tidal layer gravity waves numerical simulation

All-optical neuromorphic devices: materials, working mechanism,and applications

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Science China Chemistry 2025年

作者： Song Wang Hao Chen Hui Huang College of Materials Science and Opto-Electronic Technology Center of Materials Science and Optoelectronics Engineering CAS Center for Excellence in Topological Quantum Computation CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences College of Chemistry and Molecular Engineering Peking University

Traditional von Neumann computing, with physical separation of memory and processing units, cannot satisfy the development of artificial intelligence and cloud computing. Neuromorphic computing, inspired by the human brain, has drawn much ***-optical neuromorphic (AON) devices employ optical signals as information carriers and leverage the neuromorphic functions to implement fast operation speed, low energy consumption, and high bandwidth of neuromorphic computing. Here, we discuss the recent progress in AON devices, including materials, device performance, working mechanisms, and applications. Moreover,the advantages and limitations of AON are presented and discussed. Finally, the perspective of AON devices points out the future research direction of neuromorphic computing.

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Operando and reversible manipulation of Pt electrocatalytic properties through its substrate phase transition

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Science China Chemistry 2025年

作者： Hongfei Liu Yi Xie Changzheng Wu Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Key Laboratory of Precision and Intelligent Chemistry School of Chemistry and Materials ScienceCollaborative Innovation Center of Chemistry for Energy Materials (iChEM)and CAS Center for Excellence in NanoscienceUniversity of Science and Technology of China Institute of Energy Hefei Comprehensive National Science Center

The lattice strain is considered critical for determining the catalytic activity of metal catalysts such as Pt. However, the dynamic manipulation of Pt lattice strain under reaction conditions to directly examine its catalytic effect has not been achieved. In this study, we realized the reversible manipulation of Pt electrocatalytic properties under electrochemical conditions by tuning the Pt lattice strain with the temperature-controlled Martensite-Austenite phase transition of the shape memory NiTi alloy *** enabled establishing a straightforward relationship between the strain-induced electronic structure transformation and electrocatalytic activity leaping. The binding strength between Pt and surface oxygen species was confirmed as the critical factor that dominated the hydrogen evolution and the oxygen reduction activities. In contrast, the oxygen evolution activity was barely affected by NiTi substrate phase transition.

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Tangled but ordered human mitochondrial tRNA maturation

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Science China Life Sciences 2025年

作者： Shi-Ying Yao Xiao-Long Zhou Key Laboratory of RNA Innovation Science and Engineering CAS Center for Excellence in Molecular Cell Science Shanghai Institute of Biochemistry and Cell Biology Chinese Academy of Sciences University of Chinese Academy of Sciences Key Laboratory of Systems Health Science of Zhejiang Province School of Life Science Hangzhou Institute for Advanced Study University of Chinese Academy of Sciences

Mitochondria are cellular organelles that originate from an endosymbiotic bacterial ancestor and are primarily responsible for ATP generation via oxidative phosphorylation (OXPHOS). OXPHOS is conducted by five mitochondrial respiratory complexes in the inner mitochondrial membrane. Human mitochondria possess a distinct genome, a small, circular, doublestranded DNA (mtDNA) of 16,569 base pairs.

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Comparative analysis of empirical and deep learning models for ionospheric sporadic E layer prediction

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Earth and Planetary Physics 2025年第1期9卷 10-19页

作者： BingKun Yu PengHao Tian XiangHui Xue Christopher JScott HaiLun Ye JianFei Wu Wen Yi TingDi Chen XianKang Dou Institute of Deep Space Sciences Deep Space Exploration LaboratoryHefei 230088China cas Key Laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China Department of Meteorology University of ReadingReading RG66BBUK

Sporadic E(Es)layers in the ionosphere are characterized by intense plasma irregularities in the E region at altitudes of 90-130 *** they can significantly influence radio communications and navigation systems,accurate forecasting of Es layers is crucial for ensuring the precision and dependability of navigation satellite *** this study,we present Es predictions made by an empirical model and by a deep learning model,and analyze their differences comprehensively by comparing the model predictions to satellite RO measurements and ground-based ionosonde *** deep learning model exhibited significantly better performance,as indicated by its high coefficient of correlation(r=0.87)with RO observations and predictions,than did the empirical model(r=0.53).This study highlights the importance of integrating artificial intelligence technology into ionosphere modelling generally,and into predicting Es layer occurrences and characteristics,in particular.

关键词： ionospheric sporadic E layer radio occultation ionosondes numerical model deep learning model artificial intelligence

Populating ^(229m)Th via two-photon electronic bridge mechanism

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Nuclear Science and Techniques 2021年第6期32卷 45-53页

作者： Neng-Qiang Cai Guo-Qiang Zhang Chang-Bo Fu Yu-Gang Ma Shanghai Tech University Shanghai 201210China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Shanghai Advanced research Institute Chinese Academy of SciencesShanghai 201210China Key Laboratory of Nuclear Physics and Ion-beam Application(MOE) Institute of Modern PhysicsFudan UniversityShanghai 200433China

The isomer ^(229m)Th is the most promising candidate for clocks based on the nuclear transition because it has the lowest excitation energy of only 8.10±0.17 *** experiments and theories have focused on methods of triggering the transition between the ground state and isomeric state,among which the electronic bridge(EB)is one of the most *** this paper,we propose a new electronic bridge mechanism via two-photon excitation based on quantum optics for a two-level nuclear quantum *** long-lived 7 s1/2 electronic shell state of^(229m)Th^(3+),with a lifetime of approximately 0.6 s,is chosen as the initial state and the atomic shells(7 s-10 s)could be achieved as virtual states in a two-photon *** the virtual states return to the initial state 7 s1/2,there is a chance of triggering the nucleus 229Th^(3+),to its isomeric state ^(229m)Th ^(3+),via *** lasers at moderate intensity((10^(10)-10^(14))W/m^(2)),with photon energies near the optical range,are expected to populate the isomer at a saturated rate of approximately 10^(9) s^(-1),which is much higher than that due to other *** believe that this twophoton EB scheme can help in the development of nuclear clocks and deserves verification via a series of experiments with ordinary lasers in laboratories.

关键词： Electronic bridge ^(229)mTh Nuclear clocks Two-photon excitation

A buffer overflow detection and defense method based on RiSC-V instruction set extension

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Cybersecurity 2024年第2期7卷 28-43页

作者： Chang Liu Yan-Jun Wu Jing-Zheng Wu Chen Zhao Intelligent Software research Center Institute of SoftwareChinese Academy of SciencesBejingChina University of Chinese Academy of Sciences BeijingChina State Key Laboratory of Computer Science Institute of SoftwareChinese Academy of SciencesBeijingChina

Buffer overflow poses a serious threat to the memory security of modern operating *** overwrites the con-tents of other memory areas by breaking through the buffer capacity limit,destroys the system execution environ-ment,and provides implementation space for various system attacks such as program control flow *** makes it a wide range of harms.A variety of security technologies have been proposed to deal with system security problems including buffer *** example,No eXecute(NX for short)is a memory management technology commonly used in Harvard *** can refuse the execution of code which residing in a specific memory,and can effectively suppress the abnormal impact of buffer overflow on control ***,in recent years,it has also been used in the field of system security,deriving a series of solutions based on NX technology,such as ExecShield,DEP,StackGuard,***,these security solutions often rely too much on the processor archi-tecture so that the protection coverage is insufficient and the accuracy is *** in the emerging system architecture field represented by RiSC-V,there is still a lack of effective solutions for buffer overflow *** the continuous rapid development of the system architecture,it is urgent to develop defense methods that are applicable to different system application environments and oriented to all executable memory spaces to meet the needs of system security ***,we propose BOP,A new system memory security design method based on RISC-V extended instructions,to build a RISC-V buffer overflow detection and defense system and deal with the buffer overflow threat in *** to this method,NX technology can be combined with program control flow analysis,and Nx bit mechanism can be used to manage the executability of memory space,so as to achieve a more granular detection and defense of buffer overflow attacks that may occur in RISC-V system

关键词： RISc-V Operating system security Buffer overflow Control flow hijacking Nx bit Xibop

Carbon isotope and environmental changes in lakes in arid Northwest China

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Science China Earth Sciences 2019年第8期62卷 1193-1206页

作者： Weiguo LIU Xiangzhong LI Zheng WANG Huangye WANG Hu LIU Bo ZHANG Huan ZHANG Institute of Earth Environment CASState Key Laboratory of Loess and Quaternary GeologyXi’an 710061China University of Chinese Academy of Sciences Beijing 100049China

The stable carbon isotope composition(δ13 C) of lacustrine sediments, which can record changes in past environmental conditions such as the C4/C3 terrestrial vegetation composition, has been widely used for the reconstruction of terrestrial ecosystems and global climate changes. It has also been widely used in paleolimnological studies in arid northwestern China. In recent years, however, an increasing number of studies have enriched the environmental significance reflected by the stable carbon isotope geochemistry of lakes;therefore, the interpretation of lake δ13 C variations in paleoenvironmental reconstructions should be carefully evaluated from various aspects. In this paper, previous studies from the past several decades on the lacustrineδ13 C variations in arid northwestern China were reviewed, and the possible mechanisms of the δ13 C variations were *** study will provide a reference for the application of carbon isotope geochemistry in paleoenvironmental reconstructions.

关键词： Carbon isotope Lake Arid region of northwestern China Total organic carbon Organic biomarkers