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Synthesis and self-association of dibenzothiophene derivatives for simulation of hydrogen bonding interaction in asphaltenes

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Petroleum Science 2015年第3期12卷 501-508页

作者： Ying-Hui Bian shao-tang xu Le-Chun Song Yu-Lu Zhou Li-Jun Zhu Yu-Zhi Xiang Dao-Hong Xia State Key Laboratory of Heavy Oil Processing College of Chemical EngineeringChina University of Petroleum (East China)

The dibenzothiophene derivatives, namely 2-（dibenzothiophene-2-carbonyl）benzoic acid and 2-（diben- zothiophene-2-carbonyl）alkyl benzoate, were synthesized and characterized by nuclear magnetic resonance （1H NMR）, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and elemental analysis. The self- association behavior of these dibenzothiophene derivatives in CH2C12 and CH3CN was investigated using UV-visible absorption spectroscopy, fourier transform infrared spec- troscopy, and atomic force microscopy. It was found that the carboxylic acid exhibited a strong self-association trend in CH2C12 solution at a concentration of about 5 × 10^-7 M. Hydrogen bonding of carboxyl in the dibenzoth- iophene derivatives was confirmed to be the main driving force for the formation of the carboxylic acid aggregates.

关键词： Dibenzothiophene derivatives Association Hydrogen bonding Simulation Asphaltenes

Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

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Defence Technology（防务技术） 2024年第2期32卷 644-654页

作者： Yabei xu Jiankun shao Wei Wang Shengliang xu Dongping Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Science and Technology on Aerospace Chemical Power Laboratory Hubei Institute of Aerospace ChemotechnologyXiangyang 441003China

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical ***,the impact of the above coupling on thermal hazard assessment is not considered in the literature *** this work,nitroguanidine(NQ)and 1,3,5-trinitro-1,3,5-triazine(RDX)are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical *** linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal *** thermal decomposition curves are decoupled by advanced thermokinetics *** thermal decomposition and kinetic parameters before and after decoupling are *** results of TG experiment show that both NQ and RDX began to lose mass during the endothermic *** endothermic melting and exothermic decomposition of NQ and RDX are coupled within this *** coupling effect has different degrees of influence on its initial decomposition temperature and safety *** with the parameters in the coupling state,the initial decomposition temperature and adiabatic induction period after decoupling *** self-accelerating decomposition temperature increases,and internal thermal runaway time *** the thermal hazard assessment of chemical materials with coupling effects,the calculated parameters after decoupling should be taken as an important safety index。

关键词： Calorimetric technologies Kinetics Thermal hazard Phase transformation Thermal decomposition

High-efficiency prediction method for helicopter global/ground noise based on near-field acoustic holography

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Chinese Journal of Aeronautics 2024年第7期37卷 271-284页

作者： Mengxue shao Yang LU Xice xu Jiaxin LU National Key Laboratory of Helicopter Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Noise reduction program design is an effective approach that relies on efficient noise prediction for reducing ground noise during *** existing noise prediction methods have the limitations of being computationally expensive or only applicable to *** this paper,a High-Efficiency Prediction Method(HEPM)for helicopter global/ground noise based on near-field acoustic holography is *** HEPM can predict the global noise based on acoustic modal analysis and has the advantages of high prediction accuracy and low time *** process is given as follows:firstly,the rotor noise on the holographic surface in the specified flight is obtained by simulations or ***,the global noise model,which maps time-domain noise to acoustic modes,is established based on near-field acoustic holography and Fourier acoustic analysis ***,combined with acoustic modal amplitude,the model established enables efficiently predicting the global/ground noise in the corresponding flight *** verify the accuracy of the prediction method,a simulation study is conducted in hovering and forward flight states using a model helicopter with a 2-meter rotor and Rotor Body Interaction(ROBIN)*** comparison of HEPM with numerical results shows that the average prediction errors of the global and ground noise are less than 0.3 dB and 0.2 dB,*** a region containing 100000 observers,the computation time of the HEPM is only one-fifth of that of the acoustic hemisphere method,demonstrating the rapidity of the proposed method.

关键词： Helicopter Rotor noise prediction Noise abatement procedure design Acoustic modal analysis Near-field acoustic holography

Influences of Co-Flow and Counter-Flow Modes of Reactant Flow Arrangement on a PEMFC at Start-Up

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Computer Modeling in Engineering & Sciences 2024年第5期139卷 1337-1356页

作者： Qianqian shao Min Wang Nuo xu School of Petroleum Engineering Guangdong University of Petrochemical TechnologyMaoming525000China Mechanics Division Beijing Computational Science Research CenterBeijing100193China

To investigate the influences of co-flowand counter-flowmodes of reactant flowarrangement on a proton exchange membrane fuel cell(PEMFC)during start-up,unsteady physical and mathematical models fully coupling the flow,heat,and electrochemical reactions in a PEMFC are *** continuity equation and momentum equation are solved by handling pressure-velocity coupling using the SIMPLE *** electrochemical reaction rates in the catalyst layers(CLs)of the cathode and anode are calculated using the Butler-Volmer *** multiphase mixture model describes the multiphase transport process of gas mixtures and liquid water in the fuel *** validation,the influences of co-flow and counter-flow modes on the PEMFC performance are investigated,including the evolution of the current density,flow field,temperature field,and reactant concentration field during start-up,as well as the steady distribution of the current density,reactant concentration,andmembrane water content when the start-up ***-flow and counter-flow modes influence the current density distribution and temperature *** the one hand,the co-flow mode accelerates the start-up process of the PEMFC and leads to a more evenly distributed current density than the counter-flow *** the other hand,the temperature difference between the inlet and outlet sections of the cell is up to 10.1℃ under the co-flow mode,much larger than the 5.0℃ observed in the counter-flow ***,the counter-flowmode results in a more evenly distributed temperature and a lower maximum temperature than the co-flow ***,in the flow field design of a PEMFC,the reactant flow arrangements can be considered to weigh between better heat management and higher current density distribution of the cell.

关键词： PEMFC full coupling model Butler-Volmer equation multiphase mixture model co-flow mode counter-flow mode

Tighter sum uncertainty relations via(α,β,γ)weighted Wigner–Yanase–Dyson skew information

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Communications in Theoretical Physics 2024年第3期76卷 91-99页

作者： Cong xu Zhaoqi Wu shao-Ming Fei School of Mathematical Sciences Capital Normal UniversityBeijing 100048China Department of Mathematics Nanchang UniversityNanchang 330031China Max-Planck-Institute for Mathematics in the Sciences 04103 LeipzigGermany

We establish tighter uncertainty relations for arbitrary finite observables via(α,β,γ)weighted Wigner–Yanase–Dyson((α,β,γ)WWYD)skew *** results are also applicable to the(α,γ)weighted Wigner–Yanase–Dyson((α,γ)WWYD)skew information and the weighted Wigner–Yanase–Dyson(WWYD)skew *** also present tighter lower bounds for quantum channels and unitary channels via(α,β,γ)modified weighted Wigner–Yanase–Dyson((α,β,γ)MWWYD)skew *** examples are provided to illustrate the tightness of our uncertainty relations.

关键词： quantum channels (α,β,γ)WWYD skew information (α,β,γ)MWWYD skew information uncertainty relations

Study on force chain evolution of rice straw with different length during vibrational compression

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Particuology 2024年第2期85卷 310-322页

作者： Han tang Wenlong xu Guixuan Zhu Changsu xu Jinwu Wang College of Engineering Northeast Agricultural UniversityHarbin150030China

This paper explores the mechanism of force chain evolution and voidage change under vibrational and non-vibrational compression conditions of rice straw of different *** were used to explore the force chain evolution and voidage variation mechanism under different *** re-sults show that under non-vibrational compression,the strong force chain passes from top to bottom in vertical direction and from center to periphery in tangential *** vibrational compression,the force chain passes from top and bottom to center in vertical direction and the force chain evolves from outer ring to interior and exterior in tangential *** number of strong chains,voidage and standard deviation of the mean pressure under vibratory compression are lower than the values under non-vibratory *** promotes stress transfer and enhancement,velocity enhancement and density *** study analyzes the mechanical properties of different lengths straw during vibrational and non-vibrational compression from a detailed viewpoint.

关键词： Straw compression Voidage Discrete element method Mechanical properties Force chain transmission

A novel predictor of unsustained return of spontaneous circulation in cardiac arrest patients through a combination of capnography and pulse oximetry: a multicenter observational study

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World Journal of Emergency Medicine 2024年第1期15卷 16-22页

作者： Jing Yang Hanqi tang Shihuan shao Feng xu Yangyang Fu Shengyong xu Chen Li Yan Li Yang Liu Joseph Harold Walline Huadong Zhu Yuguo Chen xuezhong Yu Jun xu Emergency Department State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalChinese Academy of Medical Science and Peking Union Medical CollegeBeijing 100730China Emergency Department Peking University People’s HospitalBeijing 100044China Department of Emergency and Chest Pain Center Shandong Provincial Clinical Research Center for Emergency and Critical Care MedicineKey Laboratory of Emergency and Critical Care Medicine of Shandong ProvinceQilu Hospital of Shandong UniversityJinan 250012China Emergency Department Beijing Jishuitan HospitalBeijing 100035China Emergency Department Tianjin Medical University General HospitalTianjin 300052China Department of Emergency Medicine Penn State Health Milton S.Hershey Medical Center and Penn State College of MedicineHershey 17033USA

BACKGROUND:Unsustained return of spontaneous circulation(ROSC)is a critical barrier to survival in cardiac arrest *** study examined whether end-tidal carbon dioxide(ETCO_(2))and pulse oximetry photoplethysmogram(POP)parameters can be used to identify unsustained ***:We conducted a multicenter observational prospective cohort study of consecutive patients with cardiac arrest from 2013 to ***’general information,ETCO_(2),and POP parameters were collected and statistically ***:The included 105 ROSC episodes(from 80 cardiac arrest patients)comprised 51 sustained ROSC episodes and 54 unsustained ROSC *** 24-hour survival rate was significantly higher in the sustained ROSC group than in the unsustained ROSC group(29.2%vs.9.4%,P<0.05).The logistic regression analysis showed that the difference between after and before ROSC in ETCO_(2)(ΔETCO_(2))and the difference between after and before ROCS in area under the curve of POP(ΔAUCp)were independently associated with sustained ROSC(odds ratio[OR]=0.931,95%confi dence interval[95%CI]0.881-0.984,P=0.011 and OR=0.998,95%CI 0.997-0.999,P<0.001).The area under the receiver operating characteristic curve ofΔETCO_(2),ΔAUCp,and the combination of both to predict unsustained ROSC were 0.752(95%CI 0.660-0.844),0.883(95%CI 0.818-0.948),and 0.902(95%CI 0.842-0.962),***:Patients with unsustained ROSC have a poor *** combination ofΔETCO_(2) andΔAUCp showed signifi cant predictive value for unsustained ROSC.

关键词： Return of spontaneous circulation Pulse oximetry photoplethysmogram End-tidal carbon dioxide Cardiac arrest Cardiopulmonary resuscitation

The unique spontaneous polarization property and application of ferroelectric materials in photocatalysis

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Nano Research 2024年第5期17卷 3571-3585页

作者： Jinghua An Chang xu Lu Li Bo tang College of Chemistry Chemical Engineering and Materials ScienceKey Laboratory of Molecular and Nano ProbesMinistry of EducationCollaborative Innovation Center of Functionalized Probes for Chemical Imaging in University of ShandongInstitute of Molecular and Nano ScienceShandong Normal UniversityJinan 250014China Laoshan Laboratory 168 Wenhai Middle RdAoshanwei JimoQingdao 266237China

The unique spontaneous polarization property of ferroelectric material makes it to be a special catalyst in *** spontaneous polarization property can induce the formation of built-in electric field,which can improve the separation of photoelectrons and holes to affect photocatalytic *** internal electric field induced by spontaneous polarization can be influenced by multiple factors such as the morphology,the concentration of defect,the type of doped heteroatoms,as well as the composition of ***,the preparation method,pretreating temperature,the strength of prepolarized external electric field of ferroelectric-based photocatalysts as well as the strength of external mechanical force or external magnetic field in photocatalytic reactions can influence the photocatalytic effectivity via influencing spontaneous polarization-induced internal electric ***,it is urgently to unveil the mystery of structure-activity relationships for ferroelectric materials-based photocatalysts,which is usually *** this in mind,this review was provided for the role of various complex influencing factors on ferroelectric materials-based photocatalysis based on the latest advancement in the fields of new energy development,environmental *** the beginning,the basic structure and properties of ferroelectric material are ***,popular synthesis methods of ferroelectric-based photocatalysts are *** that,two main mechanisms of ferroelectric photocatalysis are *** research progress of ferroelectric photocatalysis is then given emphatically according to the classification of photocatalytic ***,the problems existing nowadays and the challenges facing in the future on the application of ferroelectric materials-based photocatalysts are outlined in the summary and outlook section.

关键词： spontaneous polarization photocatalysis ferroelectric separation of electrons and holes

Numerical study on the cavity dynamics for vertical water entries of twin spheres

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Defence Technology（防务技术） 2024年第2期32卷 459-472页

作者： xu Wang xujian Lyu Ruisheng Sun Dongdong tang School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing210094China Shanghai Institute of Spacecraft Equipment Shanghai200240China

In this study, a three dimensional(3D) numerical model of six-degrees-of-freedom(6DOF) is applied to simulate the water entries of twin spheres side-by-side at different lateral distances and time *** turbulence structure is described using the shear-stress transport k-ω(SST k-ω) model, and the volume of fluid(VOF) method is used to track the complex air-liquid interface. The motion of spheres during water entry is simulated using an independent overset grid. The numerical model is verified by comparing the cavity evolution results from simulations and experiments. Numerical results reveal that the time interval between the twin water entries evidently affects cavity expansion and contraction behaviors in the radial direction. However, this influence is significantly weakened by increasing the lateral distance between the two spheres. In synchronous water entries, pressure is reduced on the midline of two cavities during surface closure, which is directly related to the cavity volume. The evolution of vortexes inside the two cavities is analyzed using a velocity vector field, which is affected by the lateral distance and time interval of water entries.

关键词： Twin water entries Side-by-side Cavity Numerical simulation