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Design and high-power testing of offline conditioning cavity for CiADS RFQ high-power coupler

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Nuclear Science and Techniques 2024年第9期35卷 18-27页

作者： Ruo-Xu Wang Yuan He Long-Bo Shi Chen-Xing Li Zong-Heng Xue Tian-Cai Jiang Xian-Bo Xu Lie-Peng Sun Zhou-Li Zhang Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Lanzhou University Lanzhou 730000China

To validate the design rationality of the power coupler for the RFQ cavity and minimize cavity contamination,we designed a low-loss offline conditioning cavity and conducted high-power *** offline cavity features two coupling ports and two tuners,operating at a frequency of 162.5 MHz with a tuning range of 3.2 *** the installation angle of the coupling ring and the insertion depth of the tuner helps minimize cavity *** performed electromagnetic structural and multiphysics simulations,revealing a minimal theoretical power loss of 4.3%.However,when the cavity frequency varied by110 kHz,theoretical power losses increased to10%,necessitating constant tuner adjustments during *** simulations indicated that increased cavity temperature did not affect frequency *** completion of the offline high-power conditioning platform,we measured the transmission performance,revealing a power loss of 6.3%,exceeding the theoretical *** utilized efficient automatic range scanning and standing wave resonant *** fully condition the power coupler,a 15°phase difference between two standing wave points in the condition-ing system was ***,the maximum continuous wave power surpassed 20 kW,exceeding the expected target.

关键词： RFQ cavity Power coupler Offline conditioning Resonant cavity

Chalcogenide Ovonic Threshold Switching Selector

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Nano-Micro Letters 2024年第5期16卷 1-40页

作者： Zihao Zhao Sergiu Clima Daniele Garbin Robin Degraeve Geoffrey Pourtois Zhitang Song Min Zhu National Key Laboratory of Materials for Integrated Circuits Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050People’s Republic of China University of chinese academy of sciences Beijing 100029People’s Republic of China IMEC Kapedreef 75LeuvenBelgium

Today’s explosion of data urgently requires memory technologies capable of storing large volumes of data in shorter time frames,a feat unattain-able with Flash or *** Optane,commonly referred to as three-dimensional phase change memory,stands out as one of the most promising *** Optane with cross-point architecture is constructed through layering a storage element and a selector known as the ovonic threshold switch(OTS).The OTS device,which employs chalcogenide film,has thereby gathered increased attention in recent *** this paper,we begin by providing a brief introduction to the discovery process of the OTS ***,we summarize the key elec-trical parameters of OTS devices and delve into recent explorations of OTS materials,which are categorized as Se-based,Te-based,and S-based material ***,we discuss various models for the OTS switching mechanism,including field-induced nucleation model,as well as several carrier injection ***,we review the progress and innovations in OTS mechanism ***,we highlight the successful application of OTS devices in three-dimensional high-density memory and offer insights into their promising performance and extensive prospects in emerging applications,such as self-selecting memory and neuromorphic computing.

关键词： Non-volatile memory Ovonic threshold switch(OTS) Chalcogenide Selector

New record of the feather star Palaeocomatella hiwia(Echinodermata:Crinoidea:Comatulida)from Zhenbei Seamount in South China Sea:new insights into the taxonomic position of Palaeocomatella

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Journal of Oceanology and Limnology 2024年第1期42卷 244-251页

作者： Shao’e SUN Zijie MEI Zhongli SHA Jing WANG Nansheng CHEN Department of Marine Organism Taxonomy and Phylogeny Institute of OceanologyChinese Academy of SciencesQingdao 266071China CAS Key Laboratory of Marine Ecology and Environmental sciences Institute of OceanologyChinese Academy of SciencesQingdao 266071China Laoshan Laboratory Qingdao 266237China Shandong Province Key Laboratory of Experimental Marine Biology Institute of OceanologyChinese Academy of SciencesQingdao 266071China Center for Ocean Mega-Science Chinese Academy of SciencesQingdao 266071China University of chinese academy of sciences Beijing 100049China

One specimen belonging to the family Comatellinae was collected from the Zhenbei Seamount(332.5–478.2 m)in the South China Sea in July *** on the morphological characters,the specimen was identified as Palaeocomatella hiwia McKnight,*** is first recorded from China Sea and redescribed in *** specimen differs from the original description from New Zealand for never showing syzygy at br4+5 or br5+6 on interior and br1+2 on exterior ***,it is much conform to the redescription to specimens from Indonesia,with only differences in position of the second syzygy and distalmost pinnule *** is deposited in the Institute of Oceanology,chinese academy of *** analyses based on the mitochondrial c oxidase subunit I(COI)and 16S rRNA genes indicated that *** was nested within the tribe Phanogeniini and clustered with Aphanocomaster ***,*** showed same morphological features in terms of mouth placement,comb location,and number of comb teeth rows as other genera of ***,we suggest that the genus Palaeocomatella should be put in the tribe Phanogeniini.

关键词： new record Palaeocomatella hiwia McKnight 1977 South China Sea phylogenetic relationship taxonomy

Recent Advances in Mechanistic Understanding of Metal-Free Carbon Thermocatalysis and Electrocatalysis with Model Molecules

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Nano-Micro Letters 2024年第7期16卷 74-97页

作者： Wei Guo Linhui Yu Ling Tang Yan Wan Yangming Lin CAS Key Laboratory of Design and Assembly of Functional Nanostructures Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002People’s Republic of China Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen 361021People’s Republic of China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002People’s Republic of China Institute of Urban Environment Chinese Academy of SciencesXiamen 361021People’s Republic of China

Metal-free carbon,as the most representative heterogeneous metal-free catalysts,have received considerable interests in electro-and thermo-catalytic reac-tions due to their impressive performance and *** the past decade,well-designed carbon catalysts with tunable structures and heteroatom groups coupled with various characterization techniques have proposed numerous reaction ***,active sites,key intermediate species,precise structure-activity relationships and dynamic evolution processes of carbon catalysts are still rife with controversies due to the monotony and limitation of used experimental *** this Review,we sum-marize the extensive efforts on model catalysts since the 2000s,particularly in the past decade,to overcome the influences of material and structure limitations in metal-free carbon *** both nanomolecule model and bulk model,the real contribution of each alien species,defect and edge configuration to a series of fundamentally important reactions,such as thermocatalytic reactions,electrocatalytic reactions,were systematically *** with in situ techniques,isotope labeling and size control,the detailed reaction mechanisms,the precise 2D structure-activity relationships and the rate-determining steps were revealed at a molecular ***,the outlook of model carbon catalysis has also been proposed in this work.

关键词： Metal-free carbon catalysts Model catalyst Electrocatalysis Active site Reaction mechanisms

Stereoselective recognition of morphine enantiomers by μ-opioid receptor

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National Science Review 2024年第3期11卷 183-191页

作者： Yibo Wang Van A.Ngo Xiaohui Wang Laboratory of Chemical Biology Changchun Institute of Applied ChemistryChinese Academy of Sciences Advanced Computing for Life sciences and Engineering Group Science Engagement Section National Center for Computational Sciences Oak Ridge National Lab School of Applied Chemistry and Engineering University of Science and Technology of China Beijing National Laboratory for Molecular sciences

Stereospecific recognition of chiral molecules plays a crucial role in biological systems. The μ-opioid receptor（MOR） exhibits binding affinity towards（-）-morphine, a well-established gold standard in pain management, while it shows minimal binding affinity for the（+）-morphine enantiomer, resulting in a lack of analgesic activity. Understanding how MOR stereoselectively recognizes morphine enantiomers has remained a puzzle in neuroscience and pharmacology for over half-a-century due to the lack of direct observation techniques. To unravel this mystery, we constructed the binding and unbinding processes of morphine enantiomers with MOR via molecular dynamics simulations to investigate the thermodynamics and kinetics governing MOR's stereoselective recognition of morphine enantiomers. Our findings reveal that the binding of（-）-morphine stabilizes MOR in its activated state, exhibiting a deep energy well and a prolonged residence time. In contrast,（+）-morphine fails to sustain the activation state of ***, the results suggest that specific residues, namely D1142.50and D1473.32, are deprotonated in the active state of MOR bound to（-）-morphine. This work highlights that the selectivity in molecular recognition goes beyond binding affinities, extending into the realm of residence time.

关键词： stereoselective recognition thermodynamics and kinetics residence time morphine enantiomers μ-opioid receptor

Fe-N-C core-shell catalysts with single low-spin Fe(Ⅱ)-N_(4)species for oxygen reduction reaction and high-performance proton exchange membrane fuel cells

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Journal of Energy Chemistry 2024年第6期93卷 538-546,I0013页

作者： Yan Wan Linhui Yu Bingxin Yang Caihong Li Chen Fang Wei Guo Fang-Xing Xiao Yangming Lin Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of SciencesXiamen 361021FujianChina CAS Key Laboratory of Urban Pollutant Conversion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021FujianChina Fujian Institute of Research on the Structure of Matter Chinese Academy of SciencesFuzhou 350002FujianChina College of Materials Science and Engineering Fuzhou UniversityNew CampusMinhou 350108FujianChina College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350117FujianChina

Fe-N-doped carbon materials(Fe-N-C)are promising candidates for oxygen reduction reaction(ORR)relative to Pt-based catalysts in proton exchange membrane fuel cells(PEMFCs).However,the intrinsic contributions of Fe-N_(4)moiety with different chemical/spin states(e.g.D1,D2,D3)to ORR are unclear since various states coexist *** the present work,Fe-N-C core-shell nanocatalyst with single lowspin Fe(Ⅱ)-N_(4)species(D1)is synthesized and identified with ex-situ ultralow temperature Mossbauer spectroscopy(T=1.6 K)that could essentially differentiate various Fe-N_(4)states and invisible Fe-O *** quantifying with CO-pulse chemisorption,site density and turnover frequency of Fe-N-C catalysts reach 2.4×10^(-9)site g^(-1)and 23 e site~(-1)s^(-1)during the ORR,***-wave potential(0.915V_(RHE))of the Fe-N-C catalyst is more positive(approximately 54 mV)than that of Pt/***,we observe that the performance of PEMFCs on Fe-N-C almost achieves the 2025 target of the US Department of Energy by demonstrating a current density of 1.037 A cm^(-2)combined with the peak power density of 0,685 W cm^(-2),suggesting the critical role of Fe(Ⅱ)-N_(4)site(D1).After 500 h of running,PEMFCs still deliver a power density of 1.26 W cm^(-2)at 1.0 bar H_(2)-O_(2),An unexpected rate-determining step is figured out by isotopic labelling experiment and theoretical *** work not only offers valuable insights regarding the intrinsic contribution of Fe-N_(4)with a single spin state to alkaline/acidic ORR,but also provides great opportunities for developing high-performance stable PEMFCs.

关键词： Fuel cells Oxygen reduction reaction Non-platinum group metals(PGMs) Isotopic labelling Active site TOF

Twisted Phosphors that Violate Kasha's Exciton Model in Organic Systems

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chinese Journal of Chemistry 2024年第11期42卷 1237-1246页

作者： Boyi Fu Guangming Wang Jiuyang Li Junbo Li Xun Li Xiaoya Zhao Shuhui Ding Guoping Yan Qianqian Yan Kaka Zhang School of Materials Science and Engineering Wuhan Institute of TechnologyWuhanHubei430205 China Key Laboratory of Synthetic and Self-Assembly Chemistry for Organic Functional Molecules Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences345 Lingling RoadShanghai200032 China

Kasha's exciton model proposes that T1 energy levels of organic compounds are insensitive to molecular aggregation and microenvironment change because of negligible small transition dipole moments of T1 *** model holds true in most organic systems till *** we report the fabrication of twisted organic phosphors with intramolecular charge transfer characters and flexible molecular *** doped into different organic matrices,the twisted phosphor adopts different conformation,exhibits distinct phosphorescence colors and T1 energy levels,which violates Kasha's exciton model in organic *** that the change of phosphorescence colors and maxima can be readily distinguished by human eyes and conventional instrument,the twisted phosphors would be exploited as a new type of molecular probe,which would exhibit potential application in optical sensing and stimuli-responsive systems.

关键词： Afterglow Twisted phosphor Triplet excited state Room-temperature phosphorescence Luminescence Spin-orbit coupling

Particles attrition of binary mixtures in the coal-fueled chemical looping system based on fluidized bed

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Particuology 2024年第3期86卷 281-290页

作者： Heyu Li Zhe Sun Yan Cao Guangzhou Institute of Energy Conversion Chinese Academy of SciencesGuangzhou 510640China University of chinese academy of sciences Bejing 100049China CAS Key Laboratory of Renewable Energy Guangzhou 510640China Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development Guangzhou 510640China College of Chemistry and Chemical Engineering Anhui UniversityHefei230601China

In this work,a reactive air jet attrition device with auto-recording and collection of elutriated fines was *** established insights into the physiochemical interaction and further correlated attrition behaviors between char and oxygen carriers under various operation *** attrition rate increased by over 110% upon the introduced CO_(2),which brought in the significant effect of thermo-chemical stress,similarly in effects of the increased char addition ratio and the decreased sizes of char or hematite in different *** the char-hematite co-attrition process,the elutriated carbon loss of char with poor mechanical strength was found to be over 10%,while the reactive iron loss of hematite was found to be 6.3%,and was enriched in elutriated *** reaction-derived thermochemical stress and the collision-derived mechanical stress jointly controls the particle attrition during the cyclic transformation of oxygen carrier particles in coal-fueled chemical looping fluidization,especially sig-nificant in its reduction stage.

关键词： Attrition Binary species Chemical looping Oxygen carrier CO_(2)capture

Learning Sequential and Structural Dependencies Between Nucleotides for RNA N6-Methyladenosine Site Identification

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IEEE/CAA Journal of Automatica Sinica 2024年第10期11卷 2123-2134页

作者： Guodong Li Bowei Zhao Xiaorui Su Dongxu Li Yue Yang Zhi Zeng Lun Hu Xinjiang Technical Institute of Physics and Chemistry Chinese Academy of ScienceUrumqi 830011China College of Computer Xi’an Jiaotong UniversityXi’an 710049China IEEE

N6-methyladenosine(m6A)is an important RNA methylation modification involved in regulating diverse biological processes across multiple ***,the identification of m6A modification sites provides valuable insight into the biological mechanisms of complex diseases at the post-transcriptional *** a variety of identification algorithms have been proposed recently,most of them capture the features of m6A modification sites by focusing on the sequential dependencies of nucleotides at different positions in RNA sequences,while ignoring the structural dependencies of nucleotides in their threedimensional *** overcome this issue,we propose a cross-species end-to-end deep learning model,namely CR-NSSD,which conduct a cross-domain representation learning process integrating nucleotide structural and sequential dependencies for RNA m6A site ***,CR-NSSD first obtains the pre-coded representations of RNA sequences by incorporating the position information into single-nucleotide states with chaos game representation *** then constructs a crossdomain reconstruction encoder to learn the sequential and structural dependencies between *** minimizing the reconstruction and binary cross-entropy losses,CR-NSSD is trained to complete the task of m6A site *** experiments have demonstrated the promising performance of CR-NSSD by comparing it with several state-of-the-art m6A identification ***,the results of cross-species prediction indicate that the integration of sequential and structural dependencies allows CR-NSSD to capture general features of m6A modification sites among different species,thus improving the accuracy of cross-species identification.

关键词： Cross-domain reconstruction cross-species prediction N6-methyladenosine(m6A)modification site RNA sequence sequential and structural dependencies