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In-situ measurement via the flow-through method and numerical simulations for radon exhalation during measurements of the radon exhalation rate

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Nuclear Science and Techniques 2024年第7期35卷 192-207页

作者： Ming Xia Yong-Jun Ye Shan-Wei Shang Ting Yu dai-jia.chen School of Resources Environment and Safety Engineering University of South ChinaHengyang421001China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South ChinaHengyang421001China

Small-scale measurements of the radon exhalation rate using the flow-through and closed-loop methods were conducted on the surface of a uranium tailing pond to better understand the differences between the two *** abnormal radon exhalation behavior was observed,leading to computational fluid dynamics(CFD)-based simulations in which dynamic radon migration in a porous medium and accumulation chamber was *** on the in-situ experimental and numerical simulation results,variations in the radon exhalation rate subject to permeability,flow rate,and insertion depth were quantified and *** in-situ radon exhalation rates measured using the flow-through method were higher than those measured using the closed-loop method,which could be explained by the negative pressure difference between the inside and outside of the chamber during the *** consistency of the variations in the radon exhalation rate between the experiments and simulations suggests the reliability of CFD-based techniques in obtaining the dynamic evolution of transient radon exhalation rates for diffusion and convection at the porous medium-air *** synergistic effects of the three factors(insertion depth,flow rate,and permeability)on the negative pressure difference and measured exhalation rate were quantified,and multivariate regression models were established,with positive correlations in most cases;the exhalation rate decreased with increasing insertion depth at a permeability of 1×10^(−11) m^(2).CFD-based simulations can provide theoretical guidance for improving the flow-through method and thus achieve accurate measurements.

关键词： Radon exhalation Flow-through Numerical simulation Accumulation chamber Multivariate regression

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Even-odd layer-dependent multiferroic in freestanding rare-earth orthorhombic perovskite

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 151-157页

作者： Shaowen Xu Fanhao jia Ning dai School of Physics and Optoelectronic Engineering Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Department of Physics College of ScienceHangzhou Dianzi UniversityHangzhou 310018China State Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghai 200083China

Freestanding oxide perovskites possess strong interlayer coupling between adjacent atomic layers,thus exerting a determinative effect on the magnetism and ferroelectricity of these atomic-scale ***,we propose an effective strategy to manipulate magnetism and ferroelectricity in freestanding rare-earth orthorhombic perovskite via modulation of layer *** performing first-principles calculations,an even-odd oscillation is demonstrated in few-layer GdAlO_(3)perovskite(GAP).Specifically,odd-layer systems with charged atomic layers are ferromagnetic polar metals,while even-layer systems are antiferromagnetic ferroelectric *** thickness-dependent magnetic phase transition originates from carrier doping,as rationalized by the Stoner ***,we demonstrate the promotion of in-plane ferroelectricity via the concurrent application of two distinct antiferrodistortive displacements,each driven by formation and breaking of *** multiferroic phases may emerge in other transition metal oxide perovskites supporting multiple valence states,e.g.,few-layer Gd MO_(3)(M=V,Cr,Mn,and Ni).This work puts forward a strategy for layer thickness engineering of magnetism and ferroelectricity in 2D oxide perovskite multiferroic materials.

关键词： few-layer rare-earth perovskite multiferroicity size effect first principles calculations

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Near-field wideband beam training for ELAA with uniform circular array

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Science China(Information Sciences) 2024年第6期67卷 370-383页

作者： Yuhao chen Linglong dai Department of Electronic Engineering Tsinghua UniversityBeijing National Research Center for Information Science and Technology (BNRist)

Extremely large-scale antenna array(ELAA) at millimeter wave(mmWave) and Terahertz(THz)band has been considered a key technology for combating high attenuation in high-frequency bands in future6G communications. Uniform circular arrays(UCAs) have attracted much attention because of their ability to provide flat beamforming gain at all angles. To realize efficient beamforming, beam training is widely used to acquire channel state information. However, with a large antenna number, the beam training overhead in ELAA systems becomes overwhelming. Moreover, with a large bandwidth, the beam defocus effect severely degrades beam training accuracy. To address these issues, this paper proposes a frequency-dependent focusing(FDF)-based beam training scheme to realize effective beam training in near-field wideband ELAA systems with UCA. Specifically, we first analyze the FDF property of UCA, where signals at different subcarriers can simultaneously focus on different distances. Then, by exploiting the FDF property to search different distances using different subcarriers simultaneously, we design a hierarchical codebook and propose an FDFbased beam training scheme. To reveal the effectiveness of the proposed scheme, we compare its necessary beam training overhead with that of existing schemes. Finally, the simulation results demonstrate that the proposed scheme can achieve accurate beam training in near-field wideband UCA systems with a low beam training overhead.

关键词： extremely large-scale antenna array (ELAA) uniform circular array (UCA) near-field wideband beam training

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Grain refinement of 5A06 aluminum alloy welds caused by tungsten inert gas welding arc characteristics under Ar-He alternating gas supply conditions:a coupled method of water-cooled copper plate test/numerical simulation

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Journal of Iron and Steel Research International 2024年第3期31卷 767-777页

作者： Hong-bin dai jian Miao jia-xin Lin School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040HeilongjiangChina

The welding arc,as a carrier for the conversion of electrical energy to thermal energy,has a direct impact on the quality of welding by its properties and *** the tungsten inert gas(TIG)welding process under the condition of Ar-He alternating gas supply,the arc is alternately converted between Ar arc and He arc with an alternating gas supply cycle,which has obvious arc change *** FLUENT software was used to numerically simulate the characteristics of the TIG arc under the condition of alternating gas supply,and the arc temperature field,arc pressure,electric potential and current density distribution under the condition of alternating gas supply were *** with the real-time data of arc pressure measured by the water-cooled copper plate with holes,it is proved that the TIG arc has obvious dynamic characteristics under the condition of Ar-He alternating gas *** unique dynamic TIG arc acts on the 5A06 aluminum alloy weld,causing the molten pool to stir,resulting in uniform microstructure and grain refinement at the weld,and thereby improving the mechanical properties of the welded joint.

关键词： Alternating gas supply Grain refinement Numerical simulation Tungsten argon arc morphology Microstructure Mechanical property

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A self-cleaning window for high-efficiency photodegradation of indoor formaldehyde

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Chinese Chemical Letters 2024年第9期35卷 340-345页

作者： Changzhu Huang Wei dai Shimao Deng Yixin Tian Xiaolin Liu jia Lin Hong chen Department of Physics Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric PowerShanghai University of Electric PowerShanghai 200090China Shenzhen Key Laboratory of Interfacial Science and Engineering of Materials State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution ControlGuangdong Provincial Key Laboratory of Soil and Groundwater Pollution ControlSchool of Environmental Science and EngineeringSouthern University of Science and TechnologyShenzhen 518055China Eastern Institute for Advanced Study Eastern Institute of TechnologyNingbo 315200China

Formaldehyde(HCHO)as an indoor air pollutant released by new furniture and decorative materials is of great *** a self-cleaning device to remove HCHO is an ideal way to improve indoor air *** this study,a self-cleaning window with a multilayered structure constructed from fluorinedoped tin oxide/bismuth tungstate/resorcinol-formaldehyde resin(FTO/Bi_(2)WO_(6)/RF)has been fabricated,which is capable of degrading HCHO in natural indoor *** as-fabricated device could utilize the natural room light and promote the generation and transfer of the photocatalytic carriers in Bi_(2)WO_(6),which subsequently delivers a good catalytic oxygen reduction efficiency in RF to produce hydrogen peroxide(H_(2)O_(2)).The as-synthesized H_(2)O_(2)could further split into hydroxyl radicals(•OH),then oxide the HCHO molecules in the *** present study demonstrates a novel and efficient strategy to fabricate a transparent multifunctional window for self-cleaning indoor gaseous pollutants,the concept is of great importance to be expanded in a broad range of indoor furniture for in-house air pollution control.

关键词： Bismuth tungstate Resorcinol-formaldehyde Photocatalysis Hydrogen peroxide HCHO degradation

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Characterization of a New HIV-1 Circulating Recombinant Form CRF142_BC—Yunnan,China,2015 and 2021

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China CDC weekly 2024年第42期6卷 1080-1085页

作者： Min chen Huichao chen Shouxiong Lei Jie dai Yanling Ma Manhong jia Yunnan Provincial Key Laboratory of Public Health and Biosafety&Health Laboratory Center Yunnan Center for Disease Control and PreventionKunming CityYunnan ProvinceChina Institute for AIDS/STD Control and Prevention Yunnan Center for Disease Control and PreventionKunming CityYunnan ProvinceChina Division for AIDS/STD Control and Prevention Zhaotong Center for Disease Control and PreventionZhaotong CityYunnan ProvinceChina Yunnan Provincial Key Laboratory of Public Health and Biosafety&Institute for AIDS/STD Control and Prevention Yunnan Center for Disease Control and PreventionKunming CityYunnan ProvinceChina

What is already known about this topic?Recombinant strains dominate the human immunodeficiency virus 1(HIV-1)epidemic in *** Province was the first region in China to report HIV-1 infections in *** long-term HIV-1 epidemic led to the generation of various recombinant *** the 47 circulating recombinant forms(CRFs)reported in China,more than 20 were first identified in Yunnan *** is added by this report?This study reported a previously unrecognized HIV-1 CRF(CRF142_BC)characterized by the insertion of four short subtype B fragments into the subtype C ***142_BC was estimated to have emerged in the mid-1990s,close to the time of the emergence of most known CRF_BCs in *** are the implications for public health practice?The discovery of new CRFs will provide a basis for HIV-1 molecular tracing and intervention *** addition,HIV-1 recombination can alter viral biological *** study of HIV-1 gene variants needs to be intensified.

关键词： properties. China. intensified

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Stereoselective synthesis of substituted 1,3-dienes from propargylic esters: electrophilic-metal or redox catalysis?

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Science China Chemistry 2024年第5期67卷 1384-1396页

作者： Mengfu dai Liangliang Song Liang-An chen jiangsu Collaborative Innovation Center of Biomedical Functional Materials Jiangsu Key Laboratory of New Power BatteriesSchool of Chemistry and Materials ScienceNanjing Normal UniversityNanjing 210023China jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China

1,3-Diene architectures are not only widely present in natural products, pharmaceuticals, and functional organic materials but also serve as versatile building blocks to furnish important functionalized molecules in synthetic chemistry due to conjugated repeating C=C units. Accordingly, various strategies to access substituted 1,3-dienes in a stereoselective manner have been developed. However, chemo-, regio-and stereoselective synthesis of highly substituted 1,3-dienes still remains elusive and challenging. Readily available propargylic esters have emerged as an appealing class of synthetic intermediates for accessing functionalized 1,3-dienes, especially challenging tri-or tetrasubstituted variants, via transition-metal catalysis, including electrophilic metal and redox neutral catalysis. This review, for the first time, systematically highlights recent advances in transitionmetal catalyzed synthesis of substituted 1,3-dienes from propargylic esters, discusses the mechanisms and synthetic utilities, and gives the remaining challenges and potential opportunities in this field.

关键词： 1 3-diene propargylic ester Lewis acid redox catalysis transition metal

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Adipokinetic hormone signaling regulates adult dehydration resistance in the migratory locust

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Journal of Integrative Agriculture 2024年第9期23卷 3104-3117页

作者： Xianliang Huang dai Shi Kai Deng Shuzhen jia Ding Ding Li Hou Bing chen College of Life Sciences Hebei UniversityBaoding 071002China Hebei Basic Science Center for Biotic Interaction Hebei UniversityBaoding 071002China State Key Laboratory of Integrated Management of Pest Insects and Rodents Institute of ZoologyChinese Academy of SciencesBeijing 100101China

Drought events have become more severe under climate change,and this can pose a major threat to the survival of various *** molecular mechanisms involved in dehydration resistance are not well ***,adults of the migratory locust,Locusta migratoria,were subjected to food-mediated dehydration,and adipokinetic hormone(AKH)signaling was found to play a key role in regulating dehydration ***,dehydration shortened the lifespan,increased the body weight loss,and reduced the water loss rate in adult *** transcriptome profiles revealed variations in tissue-specific gene expression between dehydration-resistant locusts and normal ***,dehydration selection and exposure induced prominent expression of AKH genes in the retrocerebral complex of adult ***,individual knockdown of AKH1,AKH2,or AKH receptor(AKHR)accelerated water loss and shortened the lifespan of adult locusts under dehydration conditions,and trehalose supplementation ameliorated the negative effects caused by interference with AKH or *** findings demonstrated that AKH/AKHR signaling-dependent trehalose metabolism plays a crucial role in regulating locust dehydration resistance and thus provide novel insights into the regulatory mechanism underlying drought resistance.

关键词： adipokinetic hormone adipokinetic hormone receptor trehalose dehydration resistance Locusta migratoria

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Preparation of single atom catalysts for high sensitive gas sensing

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International Journal of Extreme Manufacturing 2024年第3期6卷 216-248页

作者： Xinxin He Ping Guo Xuyang An Yuyang Li jiatai chen Xingyu Zhang Lifeng Wang Mingjin dai Chaoliang Tan jia Zhang Key Laboratory of Microsystems and Microstructure Manufacturing Ministry of EducationHarbin Institute of TechnologyHarbin 150080People’s Republic of China Institute for Frontier Materials Deakin UniversityWaurn Ponds CampusLocked Bag 20000Victoria 3220Australia School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore 639798Singapore Department of Electrical and Electronic Engineering The University of Hong KongPokfulam RoadHong Kong Special Administrative Region of China 999077People’s Republic of China Chongqing Research Institute Harbin Institute of TechnologyChongqing 401120People’s Republic of China

Single atom catalysts(SACs)have garnered significant attention in the field of catalysis over the past decade due to their exceptional atom utilization efficiency and distinct physical and chemical *** the semiconductor-based electrical gas sensor,the core is the catalysis process of target gas molecules on the sensitive *** this context,the SACs offer great potential for highly sensitive and selective gas sensing,however,only some of the bubbles come to the *** facilitate practical applications,we present a comprehensive review of the preparation strategies for SACs,with a focus on overcoming the challenges of aggregation and low *** research efforts have been devoted to investigating the gas sensing mechanism,exploring sensitive materials,optimizing device structures,and refining signal post-processing ***,the challenges and future perspectives on the SACs based gas sensing are presented.

关键词： single atom catalysts preparation sensing mechanism gas sensing

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The Influence of the Sun and Moon on the Observation of Very High Energy Gamma-ray Sources Using EAS Arrays

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Research in Astronomy and Astrophysics 2024年第6期24卷 245-252页

作者： Tao Wen Songzhan chen Benzhong dai School of Physics and Astronomy Yunnan UniversityKunming 650091China Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Tianfu Cosmic Ray Research Center Chengdu 610000China

With great advance of ground-based extensive air shower arrays,such as LHAASO and HAWC,many very high energy(VHE)gamma-ray sources have been discovered and are being monitored regardless of the day and the ***,the Sun and Moon would have some impacts on the observation of gamma-ray sources,which have not been taken into account in previous *** this paper,the influence of the Sun and Moon on the observation of very high energy gamma-ray sources when they are near the line of sight of the Sun or Moon is *** tracks of all the known VHE sources are scanned and several VHE sources are found to be very close to the line of sight of the Sun or Moon during some *** absorption of very high energy gamma rays by sunlight is estimated with detailed method and some useful conclusions are *** main influence is the block of the Sun and Moon on gamma rays and the shadow on the cosmic ray *** influence is investigated considering the detector angular resolution and some strategies on data analysis are proposed to avoid the underestimation of the gamma-ray emission.

关键词： astroparticle physics Sun:general methods:observational Sun:UV radiation

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