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Reynolds-number scaling analysis on lift generation of a flapping and passive rotating wing with an inhomogeneous mass distribution

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Chinese Journal of Aeronautics 2024年第2期37卷 259-269页

作者： Suyang QIN Haotian HANG Yang XIANG hong liu J.C.Wu center for aerodynamics school of aeronautics and astronauticsshanghai jiao tong universityshanghai 200240china

Insects usually fly by passively rotating wings,which has been applied to the design of flapping-wing Micro-Air Vehicles(MAVs)to reduce mechanical *** this paper,a robotic passive rotating-wing model is designed to investigate wing kinematics and lift generation,which are measured by a high-speed camera and a force transducer,*** addition,flow fields are measured using the Particle Image Velocimetry(PIV).Experimental results demonstrate that passive rotating motion has a coordinative relationship with actively stroking *** the stroke amplitude or frequency increases,the rotating amplitude is *** characterize the active stroking motion,a driving Reynolds number Redrivingis defined,which varies from 68 to 366 in this *** the gravity center of the wing towards trailing ed ge induces the increase of additional torque M,which decreases the wing rotating amplitude and promotes the advance of wing *** find that the timing of wing rotation is gradually delayed and the mean lift coefficient C^(-)_(L)monotonously decreases as *** increasing the additional torque M,C^(-)_(L)is slightly improved and approaches to the lift coefficient of a real fruit fly at driving Re approximately equal to *** instantaneous lifts combined with the vortical structures further demonstrate that the lift generation associated with wing rotation is mainly attributed to the growth of the LeadingEdge Vortex(LEV)and the passive wake capture *** wake capture is influenced by LEV,reversal stroke motion and wing additional torque together,which can only maintain the lift at a high level for a considerable *** high-lift generation mechanisms of flapping and passive rotating flight could shed light on the simplified design of MAVs and the improvement of their aerodynamic performance.

关键词： Flapping flight Unsteady lift Passive rotation Vortex flow Leading-edge vortex

STRUCTURE OF MOLECULAR COMPOUND CRYSTAL A2B(A =1, 6, 7, 8,-TETRA-PHENYL （3, 4-BENZO）BICYCLO[4, 2, 0]OCTA-7-ENE, B=CIS, CIS-1,2,3,4,-TETRAPHENYLBUTADIENE)

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Chinese Journal of Structural Chemistry 1993年第5期 383-386页

作者： Huan Zhen-Wei Yao Xin-Kan Wang Ru-Ji Wang hong-gen liu Wei-Guo Department of Chemistry and Central Laboratory, Nankai University, Tianjin, 300071

C100H78, (A: C36H28, B: C28H22) Mr = 1279. 74, monoclinic, P21/a, a=17. 282(3), b=10. 669(4), c= 19, 927(3) A , β =102. 99(1)°,V = 3580. 1(2) A3, Z=2, μ(MoKα) = 0. 623cm-1, F(000) = 1356, Dc=1. 187g/cm3, room temperature. The final R=0. 084, Rw = 0. 086 for 1255 independent observed reflections (I≥3σ(I)). Owing to the existence of 1,6,7, 8-Tetraphenyl (3,4-benzo)-bicyclo[4, 2, 0]octa-7-ene(A) , cis, cts-1, 2, 3, 4-Tetraphenylbutadiene (B) in A2B can take the different conformation from the one in the pure B crystal. The reason of the formation of this molecular compound crystal is put forward.

关键词： Crystal Structure Molecular Compound A2B Type

In situ protonation in a locally flexible porous coordination polymer for enhancing proton-carrier loading and proton conductivity

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Science China Chemistry 2024年第10期67卷 3432-3437页

作者： Xianzhe Wei Jincheng liu Yan Su Weitao Wang Guixiang Wang gen Zhang Ping Wang Cheng Gu State Key Laboratory of Luminescent Materials and Devices Institute of Polymer Optoelectronic Materials and DevicesSouth China University of TechnologyGuangzhou 510640China College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China Key Laboratory for Soft Chemistry and Functional Materials of Ministry of Education School of Chemistry and Chemical EngineeringNanjing University of Science and TechnologyNanjing 210094China

Designing efficient proton-conductive materials is crucial in fuel ***,it remains a substantial challenge because of the issues in proton mobility,proton-carrier amount,and orientation of proton host ***,we report an in-situ protonation strategy to produce a locally flexible porous coordination polymer(PCP)to enhance the proton-carrier loading and proton *** local dipole flipping of the ligand allows effective proton exchange with low activation energy,promoting interpore proton transport through the pore apertures and pore *** protonation induces substantial charges to the frameworks and enhances the interaction with proton carriers,thereby increasing the loading of the proton *** this design strategy,the resulting PCP exhibits enhanced phosphoric acid loading and extraordinary proton conductivities under both aqueous and anhydrous conditions compared to its isoreticular analog that features rigidity without proton-exchange *** work provides a new avenue for designing proton-conductive materials that combine structural dynamics with performance merits.

关键词： porous coordination polymers in-situ protonation local flexibility proton-exchange mechanism proton conduction

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Influence of meteorological factors on open biomass burning at a background site in Northeast China

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Journal of Environmental Sciences 2024年第4期138卷 1-9页

作者： Yulong Wang Linlin Liang Wanyun Xu Chang liu hongbing Cheng Yusi liu gen Zhang Xiaobin Xu Dajiang Yu Peng Wang Qingli Song Jiumeng liu Yuan Cheng State Key Laboratory of Urban Water Resource and Environment School of EnvironmentHarbin Institute of TechnologyHarbin 150090China State Key Laboratory of Severe Weather&Key Laboratory for Atmospheric Chemistry Chinese Academy of Meteorological SciencesBeijing 100081China Longfengshan Regional Background Station China Meteorological AdministrationHeilongjiang 150200China Heilongjiang Climate Center Heilongjiang 150030China

Biomass burning(BB)is a very important emission source that significantly adversely impacts regional air *** produces a large number of primary organic aerosol(POA)and black carbon(BC).Besides,BB also provides many precursors for secondary organic aerosol(SOA)*** this work,the ratio of levoglucosan(LG)to organic carbon(OC)and the fire hotspots map was used to identify the open biomass burning(OBB)events,which occurred in two representative episodes,October 13 to November 30,2020,and April1 to April 30,*** ratio of organic aerosol(OA)to reconstructed PM_(2.5)concentration(PM_(2.5)^(*))increased with the increase of LG/*** LG/OC ratio is higher than 0.03,the highest OA/PM_(2.5)^(*)ratio can reach 80%,which means the contribution of OBB to OA is *** to the ratio of LG to K^(+),LG to mannosan(MN)and the regional characteristics of Longfengshan,it can be determined that the crop residuals are the main *** occurrence of OBB coincides with farmers’preferred choices,i.e.,burning biomass in“bright weather”.The“bright weather”refers to the meteorological conditions with high temperature,low humidity,and without *** factors indirectly affect regional biomass combustion pollution by influencing farmers’active choices.

关键词： Air pollution Biomass burning Meteorological factors Organic trace Agricultural fires

Effects of orientation on the fatigue crack growth behaviors of the ZK60 magnesium alloy in air and PBS

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Journal of Magnesium and Alloys 2024年第1期12卷 281-294页

作者： Jiaqi Hu Zheng liu Zuoliang Ning hong Gao School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Chemical Process Safety and Equipment Technology Tianjin 300072China

Strong anisotropic corrosion and mechanical properties caused by specimen orientations greatly limit the applications of wrought magnesium *** investigate the influences of specimen orientation,the corrosion tests and(corrosion)fatigue crack growth tests were *** rolled and transverse surfaces of the materials show distinct corrosion rate differences in the stable corrosion stage,but the truth is the opposite for the initial stage of *** air,specimen orientations have a significant influence on the plastic deformation mechanisms near the crack tip,which results in different fatigue fracture surfaces and cracking *** with R-T specimens,N-T specimens show a slower fatigue crack growth(FCG)rate in air,which can be attributed to crack closure effects and deformation twinning near the crack *** corrosion environment will not significantly change the main plastic deformation mechanisms for the same type of ***,the FCG rate in phosphate buffer saline(PBS)is one order of magnitude higher than that in air,which is caused by the combined effects of hydrogen-induced cracking and anodic *** to the similar corrosion rates at crack tips,the specimens with different orientations display close FCG rates in PBS.

关键词： Magnesium alloy Orientation Corrosion Fatigue crack growth

Navigating the complex terrain of hepatitis B virus reactivation in the era of Bruton tyrosine kinase inhibitors

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World Journal of Gastroenterology 2024年第21期30卷 2748-2750页

作者： Wei-Nung liu Ming-Shen Dai Felicia Lin gen-Min Lin Department of Medicine Tri-Service General HospitalTaipei 114Taiwan Division of Hematology/Oncology Department of Internal MedicineNational Defense Medical CenterTaipei 114Taiwan Community Care Minnesota OncologyMinneapolisMN 55404United States Department of Medicine Hualien Armed Forces General HospitalHualien City 970Taiwan

In this editorial,we offer a summary of the risk associated with hepatitis B reactivation(HBVr)in the setting of both solid and hematologic malignancies treated with Bruton tyrosine kinase(BTK)inhibitors,with insights derived from current ***,we emphasize the critical need for a framework regarding robust risk evaluation in patients undergoing such *** framework is essential for identifying those at increased risk of HBVr,enabling healthcare providers to implement proactive measures to prevent reactivation and ensure the safe administration of BTK inhibitor therapy.

关键词： Hepatitis B virus reactivation Bruton tyrosine kinase inhibitors Hematologic malignancies Solid tumors Prophylaxis guidelines

Construction of Optimal Mixed-Level Uniform Designs

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Journal of Systems Science & Complexity 2024年第2期37卷 841-862页

作者： CHATTERJEE Kashinath liu Min-Qian QIN hong YANG liuqing Department of Population Health Sciences Division of Biostatistics and Data ScienceAugusta UniversityGA 30912USA NITFID LPMC&KLMDASRSchool of Statistics and Data ScienceNankai UniversityTianjin 300071China School of Statistics and Mathematics Zhongnan University of Economics and LawWuhan 430073China

The theory of uniform design has received increasing interest because of its wide application in the field of computer *** generalized discrete discrepancy is proposed to evaluate the uniformity of the mixed-level factorial *** this paper,the authors give a lower bound of the generalized discrete discrepancy and provide some construction methods of optimal mixed-level uniform designs which can achieve this lower *** methods are all deterministic construction methods which can avoid the complexity of stochastic *** saturated mixed-level uniform designs and supersaturated mixed-level uniform designs can be obtained with these ***,the resulting designs are also χ^(2)-optimal and minimum moment aberration designs.

关键词： generalized discrete discrepancy Hadamard matrix mixed-level design orthogonal array supersaturated design

Enhanced Grain Refining Effect of Mg–Zr Master Alloy on Magnesium Alloys via a Synergistic Strategy Involving Heterogeneous Nucleation and Solute‑Driven Growth Restriction

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1354-1366页

作者： Gang Zeng hong liu Jing‑Peng Xiong Jian‑Long Li Yong liu Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province School of Advanced ManufacturingNanchang UniversityNanchang 330031China

Zirconium(Zr)emerges as the most effective grain refiner for magnesium(Mg)alloys incorporating ***,Zr is introduced in the form of an Mg–Zr master ***,within Mg–Zr master alloys,Zr predominantly exists in a particle form,which tends to aggregate due to attractive van der Waals *** clustered Zr is prone to settling,thereby reducing its refining impact on Mg *** this work,a combined pretreatment process for Mg–Zr master alloys was proposed,encompassing the introduction of a physical field to intervene the agglomeration of particle Zr and the employ of high-temperature dissolution and peritectic reactions to promote the solid solution of *** results demonstrate that the particle Zr within the pretreated Mg–Zr master alloy is effectively dispersed and refined,and greater solute Zr levels can be *** subsequent grain refinement ability was studied on a typical Mg–6Zn–0.6Zr(wt%)*** outcome highlights that an improvement in the grain refinement efficacy(32.4%)of Mg–Zr master alloys was obtained with a holding time of 60 *** pretreated Mg–Zr master alloy significantly augments the efficiency of grain refinement for Mg alloys through a synergistic strategy involving heterogeneous nucleation and solute-driven growth *** crucial factor in achieving effective grain refinement of Zr in Mg alloys lies in regulating the presence and morphology of Zr in the Mg–Zr master alloy,distinguishing between particle Zr and solute *** study introduces a novel method for developing more efficient Mg–Zr refiners.

关键词： Magnesium alloy Mg-Zr master alloy Grain refinement Heterogeneous nucleation Solute-driven growth restriction Synergistic strategy

Accelerating H^(*)desorption of hollow Mo_(2)C nanoreactor via in-situ grown carbon dots for electrocatalytic hydrogen evolution

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Journal of Energy Chemistry 2024年第9期96卷 464-471页

作者： Mengmeng liu Yuanyuan Jiang Zhuwei Cao Lulu liu hong Chen Sheng Ye School of Materials and Chemistry Anhui Agricultural UniversityHefei 230036AnhuiChina

Molybdenum carbide(Mo_(2)C)is a promising non-noble metal electrocatalyst with electronic structures similar to Pt for hydrogen evolution reaction(HER).However,strong H^(*)adsorption at the Mo sites hinders the improvement of HER ***,we synthesized monodisperse hollow Mo_(2)C nanoreactors,in which the carbon dots(CD)were in situ formed onto the surface of Mo_(2)C through carburization *** to finite element simulation and analysis,the CD@Mo_(2)C possesses better mesoscale diffusion properties than Mo_(2)C *** optimized CD@Mo_(2)C nanoreactor demonstrates superior HER performance in alkaline electrolyte with a low overpotential of 57 mV at 10 mA cm^(−2),which is better than most Mo_(2)C-based ***,CD@Mo_(2)C exhibits excellent electrochemical stability during 240 h,confirmed by operando Raman and X-ray diffraction(XRD).Density functional theory(DFT)calculations show that carbon dots cause the d-band center of CD@Mo_(2)C to shift away from Fermi level,promoting water dissociation and the desorption of H^(*).This study provides a reasonable strategy towards high-activity Mo-based HER eletrocatalysts by modulating the strength of Mo–H bonds.

关键词： Mo_(2)C nanoreactor Carbon dots H^(*)desorption Electrocatalytic hydrogen evolution