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Conformation and Counterion Distribution of Polyelectrolyte in Solution as Viewed from Dielectric Approach

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Chinese Journal of Polymer science 2024年第9期42卷 1278-1301,I0005页

作者： Kong-Shuang Zhao College of Chemistry Beijing Normal UniversityBeijing 100875China

Polyelectrolyte solutions are more variable than uncharged macromolecule due to electrical interaction between charged molecules and surrounding ***,the subject of polyelectrolyte solutions has attracted a wide range of interests in both basic and applied research,and has also been extensively ***,the understanding of the molecular dynamics and conformation of polyelectrolytes in solution remains to be deepened,and universal consensus on some key issues have not been *** methods have contributed to solving the above problems in different ways,including dielectric relaxation spectroscopy(DRS).In this perspective,we briefly reviewed the history of dielectric spectroscopic research on polyelectrolyte solution,with emphasis on summarizing our *** particular,we expound the characteristics of DRS and its ability to obtain the internal information of the system of ***,we evaluate the advantages and limitations of the dielectric method and discussed future prospects of this field.

关键词： Polyelectrolyte Dielectric relaxation spectroscopy Chain conformation Thermosensitive microgel PNIPAM microgel Spherical polyelectrolyte brushes

Dynamic characteristics and application of dual throat fluidic thrust vectoring nozzle

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Chinese Journal of Aeronautics 2024年第9期37卷 85-99页

作者： Buxian XU Dongping HU Lihao FENG Fluid Mechanics Key Laboratory of Ministry of Education Beihang UniversityBeijing 100191China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Dongfang Electric Corporation Dongfang Turbine Co.LTDDeyang 618000China

Thrust vectoring technology plays an important role in improving the maneuverability of *** order to overcome the disadvantages of mechanical thrust vectoring nozzles,such as complications of structure and significant increases in weight and cost,fluidic thrust vectoring noz-zles are *** Throat fluidic thrust vectoring Nozzle(DTN)has received wide attention due to its excellent thrust vectoring efficiency and minimal thrust *** this study,three-dimensional unsteady numerical simulations of a single axisymmetric DTN are conducted first to analyze its dynamic *** the pitch and yaw control characteristics of DTN equipped on a flying-wing aircraft are *** is found that the dynamic response will experience three stages:rapid-deflecting stage,oscillating stage,and steady stage.A complete recirculation zone forms at the end of the rapid-deflecting stage,which pushes the primary flow to attach to the wall opposite the secondary ***,the exhaust flow is *** terms of DTN's appli-cation,the DTN equipped on the flying-wing aircraft is capable of providing effective pitch and yaw moments at all angles of attack and Mach *** addition,continuous pitch and yaw moments can be obtained by adjusting the secondary mass flow *** control moment is gen-erated due to the asymmetrical pressure distribution of nozzle surface,which is mainly contributed by the pressure decrease on the secondary injection ***,the DTN equipped on the flying-wing aircraft has a relatively high thrust vectoring efficiency of around 5°/%and a thrust coefficient of around 0.95 when nozzle pressure ratio equals *** results provide an important theoretical basis for the practical application of DTN.

关键词： Dual throat nozzle Dynamic response charac-teristic Flowcontrol Flying-wing aircraft

Minimum mass-entransy dissipation profile for one-way isothermal diffusive mass-transfer process with mass-resistance and massleakage

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science china(Technological sciences) 2024年第8期67卷 2427-2435页

作者： CHEN LinGen XIA ShaoJun Institute of Thermal science and Power Engineering Wuhan Institute of TechnologyWuhan 430205China School of Mechanical Electrical EngineeringWuhan Institute of TechnologyWuhan 430205China School of Power Engineering Naval University of EngineeringWuhan 430033China

As a new concept,mass-entransy is one of the twins in the core of entransy *** can describe mass-transfer ability for masstransfer processes(MTPes),just as thermal-entransy for describing heat-transfer ***,mass-entransy dissipation can be utilized to evaluate the loss of mass-transfer *** mass-entransy dissipation(MMED) is utilized to optimize one-way isothermal diffusive MTPes with mass-leakage and mass-transfer law(g ∝ Δ(c),where c means concentration).For a given net amount of mass-transferred key components at the low-concentration side,optimality-condition for the MMED of isothermal diffusive MTPes is obtained by using the *** of the amount of mass-transferred and mass-leakage on optimal results are analyzed,and the obtained optimization profiles are compared with those for MTP profiles of constant-concentration-difference(c_1-c_2=const) and constant-concentration-ratio(c_1/c_2=const).The product of square of key-component-concentration(KCC) difference between high-and low-concentration sides and inert component concentration at high-concentration side for the MMED of the MTP with no mass-leakage is a constant,and the optimal relationship of the KCCs between high-and low-concentration sides with mass-leakage is significantly different from the *** mass-leakage is relatively small,the MTP with c_1-c_2=const strategy is superior to that with c_1/c_2=const strategy,and the latter is superior to the former with an increase in mass-leakage.A combination of mass-entransy concept,finite-time thermodynamics,and averaged-optimization-method is a meaningful tool for optimizing MTPes.

关键词： diffusive mass-transfer-law mass-leakage one-way isothermal mass-transfer minimum mass-entransy dissipation finite-time thermodynamics averaged-optimization-method

A new portable open-path instrument for ambient NH_(3) and on-road emission measurements

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Journal of Environmental sciences 2024年第2期136卷 606-614页

作者： Wenhao Dai Shanshan Wang Sanbao Zhang Jian Zhu Chuanqi Gu Zhibin Sun Ruibin Xue Bin Zhou Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3) Department of Environmental Science and EngineeringFudan UniversityShanghai 200438China Institute of Eco-Chongming(IEC) Shanghai 202162China Institute of Atmospheric sciences Fudan UniversityShanghai 200433China

Increased attentions to vehicle emission of NH_(3)have been paid since it is generally regarded as an important source in urban ***,we developed a movable instrument based on Differential Optical Absorption Spectroscopy(DOAS)principle for detecting on-road NH_(3),which can avoid the losses in the sampling process attributed to the non-sampling *** this mobile DOAS,the temporal resolution,detection limit and relative error for NH_(3)were 1 min,2.29 ppbv and 4.57%±2.44%,*** employed to the on-road measurements along the arterial highway in Shanghai,the spatial distributions of NH_(3)and NO were obtained,and their dependence of traffic and road conditions were *** slopes of linear regression between NH_(3)and NO were 0.40,0.02 and 0.07 on the Middle Ring Road,Outer Ring Road and Chongming Island Ring *** indicates that light gasoline vehicles(LGVs)were found to be the main contributor to NH_(3)emissions,while heavy-duty diesel vehicles(HDVs)mainly emitted *** on the measured NH_(3)in the tunnel,the mileagebased NH_(3)emission factor per vehicle was estimated to be 17.9±6.3 mg/*** reported open-path instrument can be broadly used in on-road pollutant monitoring or vehicle emissions,and the measurements can reveal the real situation of emission characteristics,even find the abnormal operations of vehicle catalyst system.

关键词： Ammonia Traffic emissions DOAS Emission factor Mobile measurements

Experimental investigation of junction growth of rough contacts using X-ray computed tomography

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Friction 2024年第11期12卷 2519-2531页

作者： Runliang WANG Jianhua LIU Bo LIU Duo JIA Xiaoyu DING School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China AECC Shenyang Engine Research Institution Shenyang 110000China

The real contact area(RCA)of randomly rough contacts has received a great deal of attention because it correlates strongly with friction,lubrication,sealing,and *** have revealed that the RCA associated with deterministic normal squeezing loads increases when tangential loads are also applied,in a phenomenon called junction ***,experimental investigations of the junction growth of randomly rough contacts are ***,we used X-ray computed tomography(CT)to measure junction growth when two aluminum alloy surfaces were in contact.A high-resolution experimental setup was used to apply loads and observe contact behaviors at a resolution of 4μ*** RCA and average contact gaps were computed using a three-dimensional(3D)geometric model constructed from gray CT images using the Otsu thresholding *** results showed that the RCA increased as the normal load *** RCA increased by 22.67%after a tangential load was applied(junction growth),and the average gap decreased by 14.01%after a tangential load was ***,X-ray CT accurately measured the junction growth as a novel quantitative method.

关键词： three-dimensional(3D)contact analyses real contact area(RCA),junction growth X-ray computed tomography(CT) assembly interfaces

Martensitic transformation pathways and crystallographic orientation relationships in steel

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Journal of Materials science & Technology 2024年第7期174卷 74-84页

作者： Tian-Wei Liu Xiao-Lei Wu State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering science University of Chinese Academy of SciencesBeijing 100049China

Martensite is one of the most important structures determining the ability to tailor the performance of steel and several other engineering *** previous studies,the face-centered cubic(FCC)to hexag-onal close-packed(HCP)(or body-centered cubic(BCC))martensitic transformation and the FCC to body-centered tetragonal(BCT)(or BCC)martensitic transformation during deformation and quenching were widely investigated;these transformations usually improve the plasticity and strength of steel,*** this work,detailed transmission electron microscopy(TEM)observations and electron diffraction pattern analyses of the BCT and BCC twins are performed along the[110],[131],and[¯153]zone *** transformation of BCT twins into BCC twins along the[131]zone axis is also analyzed through in situ heating during the TEM *** high-resolution TEM observations of mutually perpendicular BCT variants are consistent with the atomic arrangement obtained for the quenching pathway during the martensitic *** addition,different orientation relationships between austenite and marten-site are explained in terms of the atomic migration occurring during the deformation pathway and the quenching pathway of the martensitic transformation.

关键词： Body-centered tetragonal twin Martensitic transformation Steel Transmission electron microscopy Orientation relationship

Nano-flower spherical SnS2 combined with a special lithium storage mechanism as a multifunctional separator for lithium-sulfur batteries contributes to ultra-high initial discharge specific capacity

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science china(Technological sciences) 2024年第2期67卷 509-519页

作者： LIU HuaZhong XIONG YaPing HUANG MouZhi CHEN ZongMin YANG Xiao ZHANG Ze YANG ZhenYu CAI JianXin School of Chemistry&Chemical Engineering Nanchang UniversityNanchang 330031China

The critical factors that limit the electrochemical performance of lithium-sulfur(Li-S)batteries are mainly the“shuttle effect”of polysulfides and the slow redox reaction between lithium polysulfides(LiPSs).Herein,a nano-sphere-type material selfassembled from tin disulfide nanosheets is designed and applied to the Li-S cell separator in this *** SnS_(2)@PP modified separator not only acts as a dual restriction for LiPSs by chemisorption and physical *** the same time,it improves the catalytic activity of the redox reaction between *** SnS_(2)has extremely high electrochemical ***,a portion of the lithium ions can be inserted into SnS_(2)to form Li_(x)SnS_(2)and contribute to the capacity during the first discharge of the *** addition,Li_(x)SnS_(2)possesses a high degree of stability,and it does not undergo further de-alloying reactions even at the high potential of the Li-S *** benefit is that the steady-state Li_(x)SnS_(2)acts as a lithium-containing *** can form special Li^(+)channels on the surface of the separator,thus greatly improving the efficiency of Li+*** results showed that the SnS_(2)@PP-based cell exhibited extremely high initial discharge specific capacity(1477 m Ah g^(-1)at 0.1 C)and excellent rate performance(631 m Ah g^(-1)at 5 C).Even after 1000 cycles at 2 C,the cell exhibited a low decay rate of 0.06%per cycle on *** addition,the superior electrochemical performance was obtained even with a high sulfur loading of 5.1 mg cm^(-2)and low electrolyte of E/S=8μL mg^(-1).

关键词： Li-S batteries modified separators polysulfides catalytic conversion high electrochemical activity

Kinetic and mechanism of the reaction between Cl and several mono-methyl branched alkanes

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Journal of Environmental sciences 2024年第1期135卷 474-482页

作者： Yan Chen Weigang Wang Junling Li Li Zhou Bo Shi Cici Fan Ke Wang Hao Zhang Hong Li Maofa Ge State Key Laboratory for Structural Chemistry of Unstable and Stable Species Beijing National Laboratory for Molecular Sciences(BNLMS)CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of sciences Beijing 100049China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China national Engineering Research Center for Flue Gas Desulfurization Department of Environmental Science and EngineeringSichuan UniversityChengdu 610065China College of Chemistry and Materials science Hebei Normal UniversityShijiazhuang 050024China

Branched alkanes are ubiquitous in the troposphere and play an important role in the chemical *** this work,the rate constants and products for the reaction of Cl atoms with 3-methylhexane and 2-methylheptane were measured at room temperature(298±0.2K)and atmospheric pressure using a conventional relative rate *** rate constants of 3-methylhexane and 2-methylheptane in units of cm~3/(mol·sec)are(3.09±0.31)×10^(-10)and(3.67±0.40)×10^(-10),***,the corresponding atmospheric lifetime of the studied branched alkanes with Cl was 6.92-89.90 hours and 5.82-75.69 hours,*** estimated atmospheric lifetimes indicated that the reaction with Cl atoms could be the most important atmospheric degradation pathway for 3-methylhexane *** gas-phase products of the reactions were identified and quantified,and particle-phase products were also *** atmosphere oxidation mechanism of Cl atoms with 3-methylhexane and 2-methylheptane is *** SOA yields of 3-methylhexane and 2-methylheptane from the reaction of Cl atoms were determined to be7.96%±0.89%and 13.35%±1.50%***,the results reveal that the primary loss process of branched alkanes is the reaction with Cl atoms,which impacts its degradation on a regional scale.

关键词： 3-Methylhexane 2-Methylheptane Chlorine atoms Kinetics Mechanism

Inhibiting Voltage Decay in Li-Rich Layered Oxide Cathode:From O3-Type to O2-Type Structural Design

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Nano-Micro Letters 2024年第12期16卷 81-102页

作者： Guohua Zhang Xiaohui Wen Yuheng Gao Renyuan Zhang Yunhui Huang Institute of New Energy for Vehicles Shanghai Key Laboratory for R&D and Application of Metallic Functional MaterialsSchool of Materials Science and EngineeringTongji UniversityShanghai 201804People’s Republic of China Contemporary Amperex Technology Co. LtdNingde 352100People’s Republic of China State Key Laboratory of Material Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074HubeiPeople’s Republic of China

Li-rich layered oxide(LRLO)cathodes have been regarded as promising candidates for next-generation Li-ion batteries due to their exceptionally high energy density,which combines cationic and anionic redox ***,continuous voltage decay during cycling remains the primary obstacle for practical applications,which has yet to be fundamentally *** is widely acknowledged that voltage decay originates from the irreversible migration of transition metal ions,which usually further exacerbates structural evolution and aggravates the irreversible oxygen redox ***,constructing O2-type structure has been considered one of the most promising approaches for inhibiting voltage *** this review,the relationship between voltage decay and structural evolution is systematically *** to suppress voltage decay are systematically ***,the design of O2-type structure and the corresponding mechanism of suppressing voltage decay are comprehensively ***,the reported O2-type LRLO cathodes still exhibit partially disordered structure with extended ***,the factors that may cause the irreversible transition metal migrations in O2-type LRLO materials are also explored,while the perspectives and challenges for designing high-performance O2-type LRLO cathodes without voltage decay are proposed.

关键词： Lithium-ion batteries Li-rich layered oxide Voltage decay Migration of transition metal ions O2-type structural design