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Numerical simulations for radon migration and exhalation behavior during measuring radon exhalation rate with closed-loop method

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Nuclear Science and Techniques 2024年第1期35卷 81-95页

作者： Ming Xia Yong-Jun ye Shu-Yuan Liu School of Resources Environment and Safety Engineering University of South ChinaHengyang 421001China Key Discipline Laboratory for National Defense for Biotechnology in Uranium Mining and Hydrometallurgy University of South ChinaHengyang 421001China

Accurate measurements of the radon exhalation rate help identify and evaluate radon risk regions in the *** these measurement methods,the closed-loop method is frequently ***,traditional experiments are insufficient or cannot analyze the radon migration and exhalation patterns at the gas–solid interface in the accumulation *** CFD-based technique was applied to predict the radon concentration distribution in a limited space,allowing radon accumulation and exhalation inside the chamber intuitively and *** this study,three radon exhalation rates were defined,and two structural ventilation tubes were designed for the *** consistency of the simulated results with the variation in the radon exhalation rate in a previous experiment or analytical solution was *** effects of the vent tube structure and flow rate on the radon uniformity in the chamber;permeability,insertion depth,and flow rate on the radon exhalation rate and the effective diffusion coefficient on back-diffusion were *** on the results,increasing the inser-tion depth from 1 to 5 cm decreased the effective decay constant by 19.55%,whereas the curve-fitted radon exhalation rate decreased(lower than the initial value)as the deviation from the initial value increased by approximately 7%.Increasing the effective diffusion coefficient from 2.77×10^(-7) to 7.77×10^(-6) m^(2) s^(-1) made the deviation expand from 2.14 to 15.96%.The conclusion is that an increased insertion depth helps reduce leakage in the chamber,subject to notable back-diffusion,and that the closed-loop method is reasonably used for porous media with a low effective diffusion coefficient in view of the back-diffusion *** CFD-based simulation is expected to provide guidance for the optimization of the radon exhalation rate measurement method and,thus,the accurate measurement of the radon exhalation rate.

关键词： Radon exhalation Numerical simulation Accumulation chamber

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Rotor cross-tilt optimization for yaw control improvement of multi-rotor eVTOL aircraft

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Chinese Journal of Aeronautics 2024年第3期37卷 153-167页

作者： Xufei YAN ye YUAN Yanqin ZHAO Renliang CHEN Zhejiang Lab Hangzhou 311100China Department of Aerospace Engineering Swansea UniversitySwanseaWales SA28PPUK National Key Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Manned multi-rotor electric Vertical Takeoff and Landing(eVTOL)aircraft is prone to actuator saturation due to its weak yaw control *** address this inherent problem,a rotor cross-tilt configuration is applied in this paper,with an optimization method proposed to improve the overall control efficiency of the ***,a flight dynamics model of a 500-kg manned multi-rotor eVTOL aircraft is *** accuracy of the co-axial rotor model is verified using a single arm test bench,and the accuracy of the flight dynamics model is verified by the flight test ***,an optimization method is designed based on the flight dynamics model to calculate an optimal rotor cross-tilt mounting angle,which not only improves the yaw control efficiency,but also basically maintains the efficiency of other control *** ideal rotor cross-tilt mounting angle for the prototype is determined by comprehensively considering the optimal results with different payloads,forward flight speeds,and rotor mounting angle ***,the feasibility of the rotor cross-tilt mounting angle is proved by analyzing the control derivatives of the flight dynamics model,the test data of a ground three Degree-of-Freedom(3DOF)platform,and the actual flight data of the *** results show that a fixed rotor cross-tilt mounting angle can achieve ideal yaw control effectiveness,improving yaw angle tracking and hold ability,increasing endurance time,and achieving good yaw control performance with different payloads and forward speeds.

关键词： Multi-rotor eVTOL Control efficiency Flight dynamics model Cross-tilt optimization Endurance time

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Eigenfrequency analysis of bridges using a smartphone and a novel low-cost accelerometer prototype

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Frontiers of Structural and Civil Engineering 2024年第2期18卷 202-215页

作者： Seyedmilad KOMARIZADEHASL ye XIA Mahyad KOMARY Fidel LOZANO Department of Civil and Environment Engineering Universitat Politècnica de CatalunyaBarcelona 08034Spain Department of Bridge Engineering Tongji UniversityShanghai 200092China Department of Civil Engineering Universidad de Castilla-La ManchaCiudad Real 13071Spain

Researchers are paying increasing attention to the development of low-cost and microcontroller-based accelerometers,in order to make structural health monitoring feasible for conventional bridges with limited monitoring *** with the low-cost sensor development,the use of the embedded accelerometers of smartphones for eigenfrequency analysis of bridges is becoming popular in the civil engineering *** paper,for the first time in the literature,studies these two promising technologies by comparing the noise density and eigenfrequency analysis of a self-developed,validated and calibrated low-cost Internet of things based accelerometer LARA(low cost adaptable reliable accelerometer)with those of a state of the art smartphone(iPhone XR).The eigenfrequency analysis of a footbridge in San Sebastian,Spain,showed that the embedded accelerometer of the iPhone XR can measure the natural frequencies of the under study bridge.

关键词： smartphone modal analysis eigenfrequency analysis low-cost accelerometers Arduino Raspberry Internet of things

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Modeling and analysis of air combustion and steam regeneration in methanol to olefins processes

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Chinese Journal of Chemical Engineering 2024年第2期66卷 94-103页

作者： Jinqiang Liang Danzhu Liu Shuliang Xu Mao ye Department of Chemical Physics University of Science and Technology of ChinaHefei 230026China National Engineering Research Center of Lower-Carbon Catalysis Technology Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116021China University of Chinese Academy of Sciences Beijing 100049China

Light olefins is the incredibly important materials in chemical *** to olefins(MTO),which provides a non-oil route for light olefins production,received considerable attention in the past ***,the catalyst deactivation is an inevitable feature in MTO processes,and regeneration,therefore,is one of the key steps in industrial MTO *** the MTO catalyst is regenerated by removing the deposited coke via air combustion,which unavoidably transforms coke into carbon dioxide and reduces the carbon utilization *** study shows that the coke species over MTO catalyst can be regenerated via steam,which can promote the light olefins yield as the deactivated coke species can be essentially transferred to industrially useful synthesis gas,is a promising pathway for further MTO processes *** this work,we modelled and analyzed these two MTO regeneration methods in terms of carbon utilization efficiency and technology *** shown,the steam regeneration could achieve a carbon utilization efficiency of 84.31%,compared to 74.74%for air combustion *** MTO processes using steam regeneration can essentially achieve the near-zero carbon *** addition,light olefins production of the MTO processes using steam regeneration is 12.81%higher than that using air combustion *** this regard,steam regeneration could be considered as a potential yet promising regeneration method for further MTO processes,showing not only great environmental benefits but also competitive economic performance.

关键词： Model Methanol to olefins Regeneration Greenhouse gas Processes simulation

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Estimation of surface geometry on combustion characteristics of AP/HTPB propellant under rapid depressurization

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Defence Technology（防务技术） 2024年第3期33卷 546-558页

作者： Kaixuan Chen Zhenwei ye Xiaochun Xue Yonggang Yu School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina School of Science Hangzhou Dianzi UniversityHangzhou 310018ZhejiangChina

The 2D sandwich model serves as a potent tool in exploring the influence of surface geometry on the combustion attributes of Ammonium perchlorate/Hydroxyl-terminated polybutadiene(AP/HTPB)propellant under rapid pressure *** thickness of the sandwich propellant is derived from slicing the 3D random particle packing,an approach that enables a more effective examination of the micro-flame *** analysis of the predicted burning characteristics has been performed with experimental *** findings demonstrate a reasonable agreement,thereby validating the precision and soundness of the *** on the typical rapid depressurization environment of solid rocket motor(initial combustion pressure is 3 MPa and the maximum depressurization rate is 1000 MPa/s).A-type(a flatter surface),B-type(AP recesses from the combustion surface),and C-type(AP protrudes from the combustion surface)propellant combustion processes are numerically *** comparison of the evolution of gas-phase flame between 0.1 and 1 ms,it is discerned that the flame strength and form created by the three sandwich models differ significantly at the beginning stage of depressurization,with the flame structures gradually becoming harmonized over *** are drawn by comparison extinction times:the surface geometry plays a pivotal role in the combustion process,with AP protrusion favoring combustion the most.

关键词： AP/HTPB propellant BDP model Rapid pressure decay Burning surface geometry

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Effect of Sintering Temperature on the Microstructure and Mechanical Properties of Nanocrystalline Cemented Carbide

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 664-672页

作者：陈先富刘颖 ye Jinwen WANG Lu School of Materials Science and Engineering Sichuan UniversityChengdu 610065China Key Laboratory of Advanced Special Ma-terial&Technology Ministry of EducationChengdu 610065China

WC-Co nanocrystalline nitrogen-containing cemented carbides were prepared by vacuum sintering and low pressure *** sintering processes of Cr_(2)(C,N)doped nano WC-Co powders were studied by using thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC).The effect of sintering temperature on the microstructure and mechanical properties of nanocrystalline cemented carbide was studied by scanning electron microscope(SEM),high resolution transmission electron microscope(HRTEM)and mechanical property *** results showed that the nano WC grains began to grow in the solid phase sintering stage.A high-performance nano-nitrogen-containing cemented carbide with uniform microstructure and good interfacial bonding can be obtained by increasing the sintering temperature to 1380℃.It has a transverse rupture strength(TRS)of 5057 MPa and a hardness of 1956 HV30.

关键词： nano nitrogen cemented carbide sintering temperature microstructure mechanical properties

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Boeravinone B ameliorates allergic nasal inflammation by modulating the GATA-3/T-bet signaling pathway in a mouse model of allergic rhinitis

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Asian Pacific Journal of Tropical Biomedicine 2024年第6期14卷 245-252页

作者： Ben ye Ji-Zhe Wang Department of Otorhinolaryngology Second Hospital of Dalian Medical UniversityDalian116000China Department of Otorhinolaryngology Shandong Provincial Hospital Affiliated to Shandong First Medical UniversityJinan250000China

Objective:To evaluate the anti-allergic effect of boeravinone B against ovalbumin-induced allergic rhinitis in mice and explore its possible ***:For the induction of allergic rhinitis,mice were intraperitoneally sensitized and intranasally challenged with ovalbumin,as well as orally received various concentrations of boeravinone *** mucosal inflammation,and the levels of nitric oxide,β-hexosaminidase,IFN-γ,LTC-4,myeloperoxidase,Nrf2,HO-1,GATA-3,ROR-γ,T-bet,antioxidant parameters,and allergen-specific cytokines were ***:Boeravinone B markedly reduced ovalbumin-induced increase in the number of episodes of nasal sneezing,rubbing,and discharge,as well as the levels of IgE,IgG1,andβ-hexosaminidase(Pyeloperoxidase,oxide-nitrosative stress,and the levels of IL-1β,IL-4,IL-5,IL-6,IL-13,IL-17,tumor necrosis factor-α,GATA-3,and ROR-γwhile enhancing the level of ***:Boeravinone B is a potential therapeutic agent for allergic rhinitis by modulating various inflammatory mediators and immune responses.

关键词： Allergic reaction Boeravinone B Oxidative stress Inflammation Ovalbumin

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Hematopoietic aging:Cellular,molecular,and related mechanisms

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Chinese Medical Journal 2024年第11期137卷 1303-1312页

作者： Li ye Chuan Tian ye Li Hang Pan Jinxiu Hu Liping Shu Xinghua Pan The Stem Cells and Immune Cells Biomedical Techniques Integrated Engineering Laboratory of State and Regions Cell Therapy Technology Transfer Medical Key Laboratory of Yunnan ProvinceKunming Key Laboratory of Stem Cell and Regenerative MedicineBasic Medical Laboratory920th Hospital of Joint Logistics Support ForcePLAKunmingYunnan 650032China Department of Immunology of School of Basic Medicine of Guizhou Medical University National and Local Joint Engineering Laboratory of Cell Engineering Biomedical TechnologyKey Laboratory of Regenerative Medicine of Guizhou ProvinceState Key Laboratory of Efficacy and Utilization of Medicinal Plants Co-constructed by Province and MinistryKey Laboratory of Translational Research of Adult Stem Cell of Chinese Academy of Medical SciencesGuiyangGuizhou 550025China

Aging is accompanied by significant inhibition of hematopoietic and immune system function and disruption of bone marrow ***-related alterations in the inflammatory response,immunity,and stem cell niches are at the root of hematopoietic *** the molecular mechanisms underlying hematopoietic and bone marrow aging can aid the clinical treatment of aging-related *** particular,it is unknown how the niche reprograms hematopoietic stem cells(HSCs)in an age-dependent manner to maintain normal hematopoiesis in elderly ***,specific inhibitors and blood exchange methods have been shown to reshape the hematopoietic niche and reverse hematopoietic ***,we present the latest scientific discoveries related to hematopoietic aging and hematopoietic system rejuvenation,discuss the relationships between hematopoietic niche aging and HSC aging,and describe related studies on stem cell-mediated regulation of hematopoietic aging,aiming to provide new ideas for further study.

关键词： Stem cells Hematopoietic stem cell Niche Hematopoietic aging

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Effect of dissolved-oxygen on the flotation behavior of pyrite at high altitude area

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2148-2158页

作者： Yan Miao Guangke ye Guofan Zhang School of Minerals Processing and Bio-engineering Central South UniversityChangsha 410083China

With the continuous development of mineral resources to high altitude areas,the study of sulfide ore flotation in unconvention-al systems has been *** is a consensus that moderate oxidation of sulfide ore is beneficial to flotation,but the specific suit-able dissolved oxygen value is inconclusive,and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high *** this paper,we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N_(2)/O_(2) and dissolved oxygen under atmospheric conditions.X-ray photoelectron spec-troscopy(XPS),atomic force microscope(AFM),Fourier transform infrared spectrometer(FT-IR),UV-vis spectrophotometer,zeta po-tential,and contact angle measurements were used to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude(4600 m dissolved oxygen(DO)=4.0 mg/L).The results of pure mineral flotation indicated that the high altitude and low dissolved oxy-gen environment is favorable for pyrite *** angle measurements and XPS analysis showed that the high altitude atmosphere nslows down the oxidation of pyrite surface,facilitates S_(n)^(2-)/S^(0) production and enhances surface *** calcula-tions and zeta potential analysis showed that the influence of atmosphere on the form of pyrite adsorption is small,and the different atmo-spheric conditions are consistent with dixanthogen electrochemical adsorption,with lower Zeta potential under high altitude atmosphere and significant potential shift after sodium isobutyl xanthate(SIBX)*** results of FT-IR,UV-vis,and AFM analysis showed that SIBX adsorbed more on the surface of pyrite under high altitude atmosphere and adsorbed on the surface in a mesh structure com-posed of column/*** results of the experimental study revealed the reasons for the easy flotation of s

关键词： high altitude dissolved-oxygen pyrite flotation oxidation

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Complicated target recognition by archaeal box C/D guide RNAs

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Science China(Life Sciences) 2024年第4期67卷 631-644页

作者： Jiayin Wang Songlin Wu Keqiong ye Key Laboratory of RNA Science and Engineering CAS Center for Excellence in BiomacromoleculesInstitute of BiophysicsChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Box C/D RNAs guide the site-specific formation of 2′-O-methylated nucleotides(Nm)of RNAs in eukaryotes and *** C/D RNAs have been profiled in several archaea,their targets have not been experimentally ***,we mapped Nm in r RNAs,t RNAs,and abundant small RNAs(s RNAs)and profiled C/D RNAs in the crenarchaeon Sulfolobus *** targets of C/D RNAs were assigned by analysis of base-pairing interactions,in vitro modification assays,and gene deletion experiments,revealing a complicated landscape of C/D RNA-target interactions.C/D RNAs widely use dual antisense elements to target adjacent sites in r RNAs,enhancing modification at weakly bound *** consecutive sites can be guided with the same antisense element upstream of box D or D′,a phenomenon known as doublespecificity that is exclusive to internal box D′in eukaryotic C/D *** C/D RNAs guide modification at a single non-canonical *** study reveals the global landscape of RNA-guided 2′-O-methylation in an archaeon and unexpected targeting rules employed by C/D RNA.

关键词： C/D RNA 2′-O-methylation archaea guide RNA RNA modification

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