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Numerical investigation on the startup performance of high-temperature heat pipes for heat pipe cooled reactor application

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Nuclear Science and Techniques 2021年第10期32卷 143-155页

作者： Yu-Chuan Guo Zi-lin Su ze-guang li Kan Wang Department of Engineering Physics Tsinghua UniversityBeijing 100084China

A suitable model for high-temperature heat pipe startup is a prerequisite to realizing the numerical simula-tion for the heat pipe cooled reactor startup from the cold *** is required that this model not only describes the transient behavior during the startup period,but also reduces the computing resources of the heat pipe cooled reactor simulation in the simplest *** this study,a simplified model that integrates the two-zone and network models is *** this model,vapor flow in the vapor space,evaporation,and condensation in the vapor–liquid interface are decoupled with heat conduction to achieve a fast calculation of the transient characteristics of the heat *** experimental system for a high-temperature heat pipe was developed to validate the proposed model.A potassium heat pipe was utilized as the experimental *** experiments were performed with differ-ent heating *** with the experimental results,the accuracy of the proposed model was ***,the proposed model can predict the vapor flow,pressure drop,and temperature drop in the vapor *** indicated by the analysis results,the essential requirements for successful startup are also *** heat pipe cannot achieve a successful startup until the heating power satisfies these *** the discussions indicate the capability of the proposed model for the simulation of a high-temperature heat pipe startup from the frozen state;hence,can act as a basic tool for the heat pipe cooled reactor simulation.

关键词： High-temperature heat pipe Startup Two-zone model Network model

Hybrid windowed networks for on-the-fly Doppler broadening in RMC code

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Nuclear Science and Techniques 2021年第6期32卷 70-82页

作者： Tian-Yi Huang ze-guang li Kan Wang Xiao-Yu Guo Jin-Gang liang Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084China Department of Engineering Physics Tsinghua UniversityBeijing 100084China

On-the-fly Doppler broadening of cross sections is important in Monte Carlo simulations,particularly in Monte Carlo neutronics-thermal hydraulics coupling *** such as Target Motion Sampling(TMS)and windowed multipole as well as a method based on regression models have been developed to solve this ***,these methods have limitations such as the need for a cross section in an ACE format at a given temperature or a limited application energy *** this study,a new on-the-fly Doppler broadening method based on a Back Propagation(BP)neural network,called hybrid windowed networks(HWN),is proposed to resolve the resonance energy *** the HWN method,the resolved resonance energy range is divided into windows to guarantee an even distribution of resonance *** networks with specially designed structures and training parameters are trained to evaluate the cross section at a base temperature and the broadening *** HWN method is implemented in the Reactor Monte Carlo(RMC)code,and the microscopic cross sections and macroscopic results are *** results show that the HWN method can reduce the memory requirement for cross-sectional data by approximately 65%;moreover,it can generate keff,power distribution,and energy spectrum results with acceptable accuracy and a limited increase in the calculation *** feasibility and effectiveness of the proposed HWN method are thus demonstrated.

关键词： Monte Carlo method Reactor Monte Carlo(RMC) On-the-fly Doppler broadening BP network

Mesh‑free semi‑quantitative variance underestimation elimination method in Monte Caro algorithm

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Nuclear Science and Techniques 2023年第1期34卷 157-171页

作者： Peng‑Fei Shen Xiao‑Dong Huo ze‑guang li zeng Shao Hai‑Feng Yang Peng Zhang Kan Wang Department of Engineering Physics Tsinghua UniversityBeijing 100084China China Nuclear Power Engineering Corporation Beijing 100840China

The inter-cycle correlation of fission source distributions(FSDs)in the Monte Carlo power iteration process results in variance underestimation of tallied physical quantities,especially in large local *** study provides a mesh-free semiquantitative variance underestimation elimination method to obtain a credible confidence interval for the tallied *** method comprises two procedures:Estimation and *** FSD inter-cycle correlation length is estimated in the Estimation procedure using the Sliced Wasserstein distance *** batch method was then used in the elimination *** FSD inter-cycle correlation length was proved to be the optimum batch length to eliminate the variance underestimation *** exemplified this method using the OECD sphere array model and 3D PWR BEAVRS *** results showed that the average variance underestimation ratios of local tallies declined from 37 to 87%to within±5%in these models.

关键词： Monte Carlo algorithm Power iteration process Inter-cycle correlation Variance underestimation Sliced Wasserstein distance

Emerging progress:photochemical transformation of nitroso compounds

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Science China Chemistry 2025年第1期68卷 118-133页

作者： ze-Le Chen Qiang-Qiang li Armido Studer Jun Xuan Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials School of Chemistry&Chemical EngineeringAnhui UniversityHefei 230601China Organisch-Chemisches Institut Universitat MünsterMunster 48149Germany

Nitroso compounds have emerged as highly valuable reaction partners or reagents in organic synthesis due to their rich *** versatile profile of these compounds allows them to function as electrophiles,nucleophiles,diradicals,and radical acceptors in diverse *** recent years,notable progress has been made in harnessing photochemical reactions with nitroso compounds to prepare N,O-containing structures using mild and eco-friendly *** nitroso compounds like nitrosoarenes,acyloxy nitroso compounds,N-nitrosoamines and nitrites have received significant attention for their ability to introduce NO moieties into complex molecules that are otherwise difficult to *** this review,we provide an overview of the recent advancements in the visible light-induced conversion of nitroso compounds,with particular emphasis on their role as bifunctional reagents and acceptors of radicals,carbenes and nitrenes.

关键词： nitroso compounds photochemistry radical reaction carbene transformation nitrosoarenes

Selenate oxyanion-intercalated NiFeOOH for stable water oxidation via lattice oxygen oxidation mechanism

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Journal of Energy Chemistry 2025年第2期101卷 676-684页

作者： Yijie Zhang Weiyi Zhang Xiaowen Zhang Jinping li guang liu Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization College of Chemical Engineering and Technology Taiyuan University of Technology Shanxi Research Institute of Huai Rou Laboratory

Transition metal-based compounds can serve as pre-catalysts to obtain genuine oxygen evolution reaction（OER） electrocatalysts in the form of oxyhydroxides through electrochemical ***,the role and existence form of leached oxygen anions are still ***,we selected iron selenite-wrapped hydrated nickel molybdate（denoted as NiMoO/FeSeO） as a pre-catalyst to study the oxyanion *** is surprising to find that SeO2-exists in the catalyst in the form of intercalation,which is different from previous studies that suggest that anions are doped with residual elements after electrochemical activation,or adsorbed on the catalyst *** experiment and theoretical calculations show that the existence of SeO42-intercalation effectively adjusts the electronic structure of NiFeOOH,promotes intramolecular electron transfer and O-O release,and thus lowers the reaction energy *** expected,the synthesized NiFeOOH-SeO only needs 202 and 285 mV to attain 100 and 1000 mA cm-2in 1 M ***,the anion exchange membrane water electrolyzer（AEMWE） consisting of NiFeOOHSeO anode and Pt/C cathode can reach 1 A cm-2at 1.70 V and no significant attenuation within 300 *** findings provide insights into the mechanism,by which the intercalated oxyanions enhance the OER performance of NiFeOOH,thereby facilitating large-scale hydrogen production through AEMWE.

关键词： Anion exchange membrane electrolyzer Industrial current densities Lattice oxygen oxidation Oxyanion intercalation Water splitting

First observation results of Macao Science Satellite-1 on lightning-induced electron precipitation

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Science China Earth Sciences 2025年第1期68卷 1-10页

作者： Yongping WANG Yixin SUN Qiugang ZONG Gaopeng LU Xudong GU ze-Jun HU Bin li Key Laboratory for Polar Science Ministry of Natural ResourcesPolar Research Institute of ChinaShanghai 200136China Institute of Space Physics and Applied Technology Peking UniversityBeijing 100871China State Key Laboratory of Lunar and Planetary Science Macao University of Science and TechnologyMacao 999078China School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China School of Electronic Information Wuhan UniversityWuhan 430072China

The Medium-energy Electron Spectrometers(MES)is a space-borne instrument onboard Macao Science Satellite-1(MSS-1)dedicated to monitoring the typical charged particle radiation characteristics in the satellite orbit and the process of their occurrence and development,including short bursts of lightning-induced electron precipitation(LEP).This paper presents the first results of the LEP measurements by the MSS-1.47 LEP events are identified with the routine operation for 3 months since satellite launch,all within the range of 1.5lightning discharges are definitively geo-located for these LEP *** LEP events occur withinlightning and consist of 40–300 keV electrons.A preliminary observation result indicates that,with medium-energy electron detectors,MSS-1can present in-situ observations of large regions of enhanced background precipitation and reveal their fine spatiotemporal characteristics and spectral *** collaborative VLF ground-based measurements at the Great Wall Station,Antarctica also have a good correspondence with LEP measurements of *** observations also imply that lightning activity has a modulation effect on the energetic electron energy-spatial structure.

关键词： lightning-induced electron precipitation Inner radiation belts Energetic electrons Macao Science Satellite-1

Synthesis of intermetallic PtCo fuel cell catalysts from bimetallic core@shell structured nanoparticles

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Journal of Energy Chemistry 2025年第2期101卷 1-6页

作者： Le Zhang Lei Tong Shuai li Chang-Song Ma Kun-ze Xue Hai-Wei liang Hefei National Research Center for Physical Sciences at the Microscale Department of Chemistry University of Science and Technology of China

The high activity and stability of intermetallic PtCo nanocatalysts toward oxygen reduction reaction make them a top candidate as low-Pt cathode catalysts in proton exchange membrane fuel cells（PEMFCs）.However,forming intermetallic structures typically requires high-temperature annealing,posing a challenge for achieving well-size control and highly ordered *** we report the design and synthesis of bimetallic co re@shell structured precursors for affording high-performance intermetallic PtCo *** fabrication of the core@shell precursor involves using a molecular ligand containing both sulfur and oxygen donors to selectively bind with Pt colloidal nanoparticles as the core and chelate Co ions as the *** high-temperature annealing,the ligand transforms into carbon coatings around alloy nanoparticles,preventing particle sintering;meanwhile,Co ions in the shell can easily diffuse into the Pt core,which helps to increase the thermodynamic driving force for forming intermetallic *** benefits enable us to obtain the catalyst with finely dispersed nanoparticles（～3.5 nm）and a high ordering degree of 72%.With 0.1 mgPt/cm2cathode loading,the catalyst delivers superior performance and durability in PEMFCs,showing an initial mass activity of 0.56 A/mgPt,an initial power density of 1.05 W/cm2at 0.67 V（H2-air）,and a voltage loss of 26 mV at 0.8 A/cm2after the accelerated durability test.

关键词： Bimetallic structure Fuel cells Intermetallic PtCo Oxygen reduction reaction

Systematic review of amyloid-beta clearance proteins from the brain to the periphery:implications for Alzheimer's disease diagnosis and therapeutic targets

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Neural Regeneration Research 2025年第12期20卷 3574-3590页

作者： Letian Huang Mingyue liu ze li Bing li Jiahe Wang Ke Zhang Department of Oncology Shengjing Hospital of China Medical UniversityShenyangLiaoning ProvinceChina Department of Developmental Cell Biology Key Laboratory of Cell BiologyMinistry of Public HealthChina Medical UniversityShenyangLiaoning ProvinceChina Department of Family Medicine Shengjing Hospital of China Medical UniversityShenyangLiaoning ProvinceChina

Amyloid-beta clearance plays a key role in the pathogenesis of Alzheimer's disease.H oweve r,the variation in functional proteins involved in amyloid-beta clearance and their correlation with amyloid-beta levels remain unclea *** this study,we conducted meta-analyses and a systematic review using studies from the PubMed,Embase,Web of Science,and Cochrane library databases,including journal articles published from inception to J une 30,*** inclusion criteria included studies comparing the levels of functional proteins associated with amyloid-beta clearance in the blood,cere b rospinal fluid,and brain of healthy controls,patients with mild cognitive impairment,and patients with Alzheimer's ***,we analyzed the correlation between these functional proteins and amyloid-beta levels in patients with Alzheimer's *** methodological quality of the studies was assessed via the Newcastle-Ottawa *** to heterogeneity,we utilized either a fixed-effect or random-effect model to assess the 95%confidence interval(CI)of the standard mean difference(SMD)among healthy controls,patients with mild cognitive impairment,and patients with Alzheimer's *** findings revealed significant alterations in the levels of insulin-degrading enzymes,neprilysin,matrix metalloproteinase-9,cathepsin D,receptor for advanced glycation end products,and P-glycoprotein in the brains of patients with Alzheimer's disease,patients with mild cognitive impairment,and healthy *** cerebrospinal fluid,the levels of triggering receptor expressed on myeloid cells 2 and ubiquitin C-terminal hydrolase L1 are altered,whereas the levels of TREM2,CD40,CD40L,CD14,CD22,cathepsin D,cystatin C,andα2 M in peripheral blood ***,TREM2 and cathepsin D showed changes in both brain(SMD=0.31,95%CI:0.16-0.47,P<0.001,I^(2)=78.4%;SMD=1.24,95%CI:0.01-2.48,P=0.048,I^(2)=90.1%)and peripheral blood(SMD=1.01,95%CI:0.35-1.66,P=0.003,I^(2)=96.5%;SMD=7.55,95%CI:3.92-11.18,P<0.001,I^(

关键词： Alzheimer’s disease amyloid-β blood‒brain barrier cerebrospinal fluid diagnostic biomarker meta-analysis mild cognitive impairment peripheral blood systematic review therapeutic targets

Experimental study on the buckling of composite cylinders with reinforced circular hole under hydrostatic pressure

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Defence Technology(防务技术) 2025年第2期44卷 231-247页

作者： Zhun li Xinhu Zhang Kechun Shen Jing liu Jian Zhang guang Pan School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Northwest Institute of Mechanical and Electrical Engineering Xianyang 712099China Jiangsu University of Science and Technology Zhenjiang 212003China

In this paper,a type of reinforcing structure for composite shell with single and through hole is *** experimental tests for the composite shells without hole,with single hole and reinforced structure,with through hole and reinforced structure subjected to hydrostatic pressure were carried out by the designed experimental test *** mechanical responses of the composite shells under hydrostatic pressure are obtained by the high-speed camera and strain *** results show that the entire deformation process of the shell can be divided into three:uniform compression,"buckling mode formation"and ***"buckling mode formation"process is captured and reported for the first *** the composite shell with single hole,the proposed reinforcing structure has a significant reinforcement effect on the shell and the buckling capacity of the shell is not weaker than the complete composite *** the composite shell with through hole,sealing effect can be achieved by the proposed reinforcing structure,but the buckling capacity of the shell after reinforcement can only reach 77%of the original buckling capacity.

关键词： Composite cylindrical shell Circular hole Reinforcing structure Buckling Hydrostatic pressure