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Geometrical transition properties of vortex cavitation and associated flow-choking characteristics in poppet valves

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第6期25卷 455-469页

作者： Liang LU Zhongdong LIANG Yuming LIU Zhipeng WANG Shohei ryu School of Mechanical Engineering Tongji UniversityShanghai 201804China Frontiers Science Center for Intelligent Autonomous Systems Tongji UniversityShanghai 201210China Technical Research Laboratory Hitachi Construction Machinery Co.Ltd.Tsuchiura 300-0013Japan

Poppet valves have become increasingly significant in ensuring precise digital flow rate and pressure control in hydraulic systems,necessitating a more profound understanding of the geometrical properties of cavitation in them,as well as associated flow-choking *** a comparative analysis with experimentally observed cavity images,we found that large eddy simulation(LES)turbulence modeling effectively replicates the geometrical properties of cavitation in these *** analysis demonstrated that cavitation is generated from vortices that result from the interaction between the notch contracta flow and the surrounding fluid *** in the internal or external vena contracta conditions result in fixed or discrete cavities,and the length-to-diameter ratio serves as a measure of the transition between internal and external vena contracta flow *** study establishes a threshold length-to-diameter ratio of approximately 2 for the tested poppet *** specifically,in notch structures with a smaller valve opening,longer sealing length,and smaller throttling angle(corresponding to a larger length-to-diameter ratio),the liquid-to-vapor transfer process is more evident than that in the reverse direction.A long-standing vapor cavity becomes fixed inside the notch,leading to a more pronounced flow-choking *** contrast,for structures with a smaller length-to-diameter ratio,the cavitation process for discrete vapor cavities is more complete,ensuring fluid flow continuity and significantly reducing the occurrence of the flow-choking phenomenon.

关键词： Poppet valves Vena contracta Vortex flow Vapor cavity Flow-choking

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Air-stable,all-dry transferred ReS_(2)/Gase heterostructure-based NO_(2)gas sensor

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Journal of Materials Science & Technology 2024年第1期168卷 79-87页

作者： A.Venkatesan Hyeyoon ryu Anupom Devnath Hyungyu Yoo seunghyun Lee Department of Electronic Engineering Kyung Hee UniversityYongin-Si 17104South Korea Department of Electronics and Information Convergence Engineering Kyung Hee UniversityYongin-Si 17104South Korea

Two-dimensional(2D)materials have gained considerable attention in chemical sensing owing to their naturally high surface-to-volume ***,the poor response time and incomplete recovery re-strict their application in practical,high performance gas *** this work,we fabricated air-stable ReS_(2)/Gase heterostructure-based NO_(2)gas sensors with excellent gas sensing response,recovery,selectiv-ity and a low limit of detection(LOD)toward nitrogen dioxide(NO_(2)).The ReS_(2)/Gase heterostructure was prepared via mechanical exfoliation and an all-dry transfer *** the sensing measurements,temperature-dependant transport measurements were carried *** Schottky Barrier Height(SBH)of the ReS_(2)/Gase heterostructure was calculated and the corresponding transport mechanisms were *** fabricated gas sensors showed a significant response enhancement with full reversibility to-ward ppm-level NO_(2)(response of∼17%at 3 ppm,a LOD of∼556 ppb)at an operating temperature of(33°C).In particular,the total response and recovery time of the ReS_(2)/Gase was revealed to be less than 4 min(∼38 s and∼174 s,respectively)for the 250 ppm concentration,which is one of the best response and recovery time toward ppm-level NO_(2).The excellent sensing performances and recovery characteris-tics of the ReS_(2)/Gase structure are attributed to its efficient charge separation,unique interlayer coupling and desirable band *** atomically thin,ultrasensitive gas sensor that operates at room tem-perature is a strong technological contender to conventional metal oxide gas sensors,which often require elevated temperatures.

关键词： 2D materials All-dry transfer Gas sensor Van der Waals heterostructure ReS_(2)/Gase Gas sensing response Transition metal dichalcogenide

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Recent progress and future directions of the research on nanoplastic-induced neurotoxicity

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Neural Regeneration Research 2024年第2期19卷 331-335页

作者： seung-Woo Han Jinhee Choi Kwon-Yul ryu Department of Life Science University of SeoulSeoulSouth Korea School of Environmental Engineering University of SeoulSeoulSouth Korea

Many types of plastic products,including polystyrene,have long been used in commercial and industrial *** and nanoplastics,plastic particles derived from these plastic products,are emerging as environmental pollutants that can pose health risks to a wide variety of living organisms,including ***,it is not well understood how microplastics and nanoplastics affect cellular functions and induce stress *** can be exposed to polystyrene-microplastics and polystyrene-nanoplastics through ingestion,inhalation,or skin *** ingested plastics are excreted from the body,but inhaled plastics may accumulate in the lungs and can even reach the brain via the nose-to-brain ***-sized polystyrene-nanoplastics can enter cells by endocytosis,accumulate in the cytoplasm,and cause various cellular stresses,such as inflammation with increased pro-inflammatory cytokine production,oxidative stress with generation of reactive oxygen species,and mitochondrial *** induce autophagy activation and autophagosome formation,but autophagic flux may be impaired due to lysosomal *** permanently exposed to polystyrene-nanoplastics,they can be removed from cells by exocytosis and subsequently restore cellular ***,neurons are very susceptible to this type of stress,thus even acute exposure can lead to neurodegeneration without *** review focuses specifically on recent advances in research on polystyrene-nanoplastic-induced cytotoxicity and ***,in this review,based on mechanistic studies of polystyrene-nanoplastics at the cellular level other than neurons,future directions for overcoming the negative effects of polystyrene-nanoplastics on neurons were suggested.

关键词： autophagy cellular stress cytotoxicity endocytosis exocytosis inflammation microplastics nanoplastics neurotoxicity oxidative stress polystyrene

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The association between C-reactive protein to albumin ratio and 6-month neurological outcome in patients with in-hospital cardiac arrest

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World Journal of Emergency Medicine 2024年第3期15卷 223-228页

作者： Ji Ho Lee Dong Hun Lee Byung Kook Lee seok Jin ryu Department of Emergency Medicine Chonnam National University HospitalGwangju 61469Republic of Korea Department of Emergency Medicine Chonnam National University Medical SchoolGwangju 61469Republic of Korea

The global incidence rates of in-hospital cardiac arrest(IHCA)range from1.2 to 9.0 per1,000 hospitalized patients,as per the National Cardiac Arrest Database.[1] While IHCAs tend to exhibit superior 30-day survival rates relative to out-of-hospital cardiac arrests (OHCA) due to situational advantages,such as immediate access to medical personnel and treatments.

关键词： patients cardiac IHC

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On von Neumann Regularity of Commutators

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Algebra Colloquium 2024年第2期31卷 181-198页

作者： Nam Kyun Kim Tai Keun Kwak Yang Lee Sung Ju ryu Nanqing Ding School of Basic Sciences Hanbat National UniversityDaejeon 34158Korea Department of Data Science Daejin UniversityPocheon 11159Korea Department of Mathematics Yanbian UniversityYanjiJilin 133002China Institute for Applied Mathematics and Optics Hanbat National University Daejeon 34158Korea Department of Mathematics Pusan National UniversityBusan 46241Korea 不详

We study the structure of rings which satisfy the von Neumann regularity of commutators,and call a ring R C-regularif ab-ba ∈(ab-ba)R(ab-ba)for all a,b in *** a C-regular ring R,we prove J(R[X])=N^(*)(R[X])=N^(*)(R)[X]=W(R)[X]■Z(R[X]),where J(A),N^(*)(A),W(A),Z(A)are the Jacobson radical,upper nilradical,Wedderburn radical,and center of a given ring A,respectively,and A[X]denotes the polynomial ring with a set X of commuting indeterminates over A;we also prove that R is semiprime if and only if the right(left)singular ideal of R is *** provide methods to construct C-regular rings which are neither commutative nor von Neumann regular,from any given ***,for a C-regular ring R,the following are proved to be equivalent:(i)R is Abelian;(ii)every prime factor ring of R is a duo domain;(ii)R is quasi-duo;and(iv)R/W(R)is reduced.

关键词： C-regular ring commutator regular ring commutative ring radical singular ideal

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Applying heteroatom co-doped carbon nanotube for manifesting high performance in the electrochemical reduction of aqueous nitrogen oxide by gold nanoparticles

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Nano Research 2024年第3期17卷 1151-1164页

作者： Jane Chung Haibo Yin Rong Wang Yunlong Wang Junyang Zhang Yue Peng Joung Woo Han seongyun ryu Junhua Li State Key Joint Laboratory of Environment Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing 100084China EHS Research Center Samsung Electronics Co.Ltd.Gyeonggi-do 18448Republic of Korea

Electrochemical NO-to-NH_(3) under ambient conditions could be a viable alternative having advantages in terms of energy consumption and exhaust gas recycling of NO,replacing a traditional ammonia synthesis method of the Haber–Bosch *** synthesizing boron(B-)and nitrogen(N-)co-doped carbon nanotube(CNT)based gold(Au)catalysts,B-dopants elevate the conductivity of carbon nanotube by sp2 hybridization on graphene and implant B–N domains within the graphene layer,and result in facilitating the embedding amount of Au accompanied by high dispersibility with low particle *** density functional theory(DFT)calculations elucidate that the electron cloud transmitted from B-dopant to the active site of Au induces the Lewis acidic site,and the O-distal pathway occurs following a spontaneous *** of the electron-deficient B-doping area accompanied by N-defects and B–O edges retains the major valence state of Au as Au^(δ+),and suppresses hydrogen evolution reaction(HER)by repulsing the hindrance of H*.This record exhibits the highest faradaic efficiency(FE)of 94.7%,and NH_(3) yield rate of 1877.4μg·h^(-1)·mg_(cat)^(-1),which is the optimal yield over energy consumption in the field of the ambient reduction of aqueous NO.

关键词： boron heteroatom nitrogen defect gold nanoparticles valence states of gold electrochemical NO-to-NH3

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Intracellular zinc signaling via Kruppel-like transcription factor 6 promotes HuD expression in pancreatic β cell

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Genes & Diseases 2024年第4期11卷 24-27页

作者： se.ngho Cha Chongtae Kim Myeongwoo Jung seungyeon ryu Sukyoung Han Wook Kim Eun Kyung Lee Department of Biochemistry Department of Biomedicine&Health SciencesCollege of MedicineThe Catholic University of KoreaSeoul 06591South Korea Catholic Institute for Visual Science College of MedicineThe Catholic University of KoreaSeoul 06591South Korea Department of Molecular Science&Technology Ajou UniversitySuwon 16499South Korea

Dysfunction of pancreaticβcells caused by zinc deficiency is related to the pathogenesis of diabetes.1 Impaired zinc homeostasis in diabetes is associated with reduced zinc transporters.2 Down-regulation of HuD,an es... 详细信息

关键词： βcell homeostasis zinc

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Tetradentate Pt(Ⅱ)complex as a singlet exciton sensitizing host for highly efficient green fluorescent organic light-emitting diodes

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Science China Materials 2024年第8期67卷 2618-2627页

作者： Unhyeok Jo seung Chan Kim Chan Hee ryu Kang Mun Lee Jae-Min Kim Jun Yeob Lee School of Chemical Engineering Sungkyunkwan University2066Seobu-roJangan-guSuwon-siGyeonggi-do 16419Republic of Korea Department of Chemistry Institute for Molecular Science and Fusion TechnologyKangwon National UniversityChuncheonGangwon 24341Republic of Korea Department of Advanced Materials Engineering Chung-Ang University4726Seodong-daeroDaedeok-myeonAnseong-siGyeonggi-do 17546Republic of Korea SKKU Advanced Institute of Nano Technology Sungkyunkwan University2066Seobu-roJangan-guSuwonGyeonggi 16419Republic of Korea SKKU Institute of Energy Science and Technology Sungkyunkwan University2066Seobu-roJangan-guSuwonGyeonggi 16419Republic of Korea

Efficient green fluorescent organic light-emitting diodes were designed with a phosphorescent metal complex as a singlet exciton sensitizing host(seSH)for achieving high efficiency and low efficiency roll-off through exciton and polaron *** Pt(Ⅱ)complex(Pt-Trz)possessing a tetradentate ligand with a bulky blocking group not only suppresses the severe formation of excimer or dimer itself but also transfers radiative excitons to fluorescent dopant *** seSH assisted fluorescence(seSHF)device with Pt-Trz as the host exhibits the maximum external quantum efficiency of 13.3%and a lower efficiency roll-off compared with exciplex host device which is a general approach for harvesting triplet *** exciton dynamics modeling unravels that the seSHF device effectively utilizes triplet excitons in the host by intersystem crossing and resonance energy transfer from the triplet state of the host to the singlet state of the terminal *** quenching rates of the seSHF device are reduced by 11 times for triplet-triplet annihilation and 1.8 times for tripletpolaron annihilation compared with the exciplex device,which demonstrates that Pt-Trz could be a platform to be used as an efficient host for fluorophores.

关键词： singlet annihilation polaron

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Helping People and Changing the World with CS

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计算机教育 2024年第3期 17-19页

作者： Sukyoung ryu School of Computing Korea Advanced Institute of Science and Technology291 Daehak-roYuseong-gu Daejeon 34141Korea

What should academic institutions be doing in order to benefit students,the community at large,and society in the new era?Particularly,as computing is impacting all aspects of human society,it also brings many challenges and opportunities for the academic departments of computer *** of these challenges include the increasing impact of software on society,issues involving privacy and data abuse,and ethical issues concerning *** addressing these challenges,the Korea Advanced Institute of Science and Technology(KAIST)leverages its position as an educator in order to train the future computing workforce to be more aware of these *** achieve this goal,KAIST mainly adopts three strategies:Combining science&technology and humanities together;putting academy and industry together;training software experts while making them understand people and the world.

关键词： Computing KAIST Privacy and data abuse Ethical issues

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锥阀漩涡空化几何形态变迁与流量饱和特性（英文）

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第6期 455-469页

作者：陆亮梁中栋刘禹明王志鹏 Shohei ryu 同济大学机械与能源工程学院同济大学教育部自主智能无人系统前沿科学中心日立建机株式会社技术研究实验室

目的：伴随数字阀在流体控制中日益体现的高端品质，锥阀作为数字阀的主要阀芯结构，其空化与流量饱和问题日益受到重视。本文借助实验与仿真手段，旨在揭示漩涡空化成形机理及其伴随孔口长径比形态变迁的物理规律，以及大尺度空化对流... 详细信息

目的：伴随数字阀在流体控制中日益体现的高端品质，锥阀作为数字阀的主要阀芯结构，其空化与流量饱和问题日益受到重视。本文借助实验与仿真手段，旨在揭示漩涡空化成形机理及其伴随孔口长径比形态变迁的物理规律，以及大尺度空化对流量饱和的影响特性，为高品质锥阀结构设计提供基础依据。创新点：1.应用流束收缩理论定义锥阀固定型与离散型空化的漩涡成型机理与形态变迁规律；2.使用大涡模拟合理复现空化形态并揭示空化对流量饱和的影响规律。方法：1.通过可视化实验，获得锥阀空化的几何形态，并验证数值模型的合理性；2.通过数值计算，研究空化形态随锥阀结构的变化规律；3.利用阀口开度、密封长度和阀芯半锥角三个参数定义长径比无量纲指标，衡量空化形态与流量饱和特性的变化规律。结论：1.锥阀阀口流束内外收缩性质的不同，导致阀口内部固定漩涡与阀口下游离散漩涡的差异，进而形成固定漩涡空化和离散漩涡空化的形态区别。2.使用阀口开度、密封长度和阀芯半锥角定义阀口等效长径比，可用于评价空化几何形态的变迁规律。3.固定漩涡空化对流量饱和的影响程度较大；离散漩涡空化因完整的溃灭过程而对流量饱和影响较小。

关键词：锥阀流束收缩漩涡流动蒸汽空穴流量饱和

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