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Friction 2024年第5期12卷 1042-1056页

作者： Anastasiya A.YAKOVENKO Irina G.GORYACHEVA Ishlinsky institute for problems in Mechanics RAS Moscow119526Russia

The contact of a rigid body with nominally flat rough surface and an elastic half-space is considered.To solve the contact problem,the Greenwood-Williamson statistical model and the localization principle are used.The developed contact model allows us to investigate the surface approach and the real contact area with taking into account the asperities interaction.It is shown that the mutual influence of asperities changes not only contact characteristics at the macroscale,but also the contact pressure distribution at the microscale.As follows from the results,the inclusion in the contact model of the effect of the mutual influence of asperities is especially significant for studying the real contact area,as well as the contact characteristics at high applied loads.The results calculated according to the proposed approach are in a good agreement with the experimentally observed effects,i.e.,the real contact area saturation and the additional compliance exhaustion.

关键词： surface roughness elasticity Greenwood-Williamson model localization principle asperity interaction

Active and passive modulation of solar light transmittance in a uniquely multifunctional dual-band single molecule for smart window applications

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Journal of Energy Chemistry 2024年第1期88卷 293-305,I0007页

作者： Pooja V.Chavan Pramod V.Rathod Joohyung Lee Sergei V.Kostjuk Hern Kim Department of Energy Science and Technology Environmental Waste Recycle InstituteMyongji UniversityYonginGyeonggi-do 17058Republic of Korea Department of Chemical Engineering Myongji UniversityYonginGyeonggi-do 17058Republic of Korea Research institute for physical Chemical problems of the Belarusian State University MinskBelarus

Functional materials may change color by heat and electricity separately or simultaneously in smart windows.These materials have not only demonstrated remarkable potential in the modulation of solar radiation but are also leading to the development of indoor environments that are more comfortable and conducive to improving individuals'quality of life.Unfortunately,dual-responsive materials have not received ample research attention due to economic and technological challenges.As a consequence,the broader utilization of smart windows faces hindrances.To address this new generational multistimulus responsive chromic materials,our group has adopted a developmental strategy to create a poly(NIPAM)n-HV as a switchable material by anchoring active viologen(HV)onto a phase-changing poly(NIPAM)n-based smart material for better utility and activity.These constructed smart windows facilitate individualistic reversible switching,from a highly transparent state to an opaque state(thermochromic)and a red state(electrochromic),as well as facilitate a simultaneous dual-stimuli response reversible switching from a clear transparent state to a fully opaque(thermochromic)and orange(electrochromic)states.Absolute privacy can be attained in smart windows designed for exclusive settings by achieving zero transmittance.Each unique chromic mode operates independently and modulates visible and near-infrared(NIR)light in a distinct manner.Hence,these smart windows with thermal and electric dual-stimuli responsiveness demonstrate remarkable heat regulation capabilities,rendering them highly attractive for applications in building facades,energy harvesting,privacy protection,and color display.

关键词： Smart windows Thermochromism Electrochromism Energy saving Dual-responsive material

Convection and Stratification of Temperature and Concentration

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Fluid Dynamics & Materials Processing 2024年第6期20卷 1351-1364页

作者： Alexey Fedyushkin Laboratory of Complex Fluid Mechanics Ishlinsky Institute for Problems in Mechanics RASMoscow119526Russia

This study is devoted to an analysis of natural convection and the emergence of delamination in an incompressible fluid encapsulated in a closed region heated from the side.Weak,medium and intensive modes of stationary laminar thermal and thermo-concentration convection are considered.It is shown that nonlinear flow features can radically change the flow structure and characteristics of heat and mass transfer.Moreover,the temperature and concentration segregation in the center of the square region display a non-monotonic dependence on the Grashof number(flow intensity).The formation of a nonstationary periodic structure of thermal convection in boundary layers and in the core of a convective flow in the closed region is also examined.Details of the formation of countercurrents inside the region with the direction opposite to the main convective flow are given.Finally,the influence of vertical and horizontal vibrations on oscillatory convection is analyzed in detail.

关键词： Natural convection stratification segregation numerical simulation vibrations

HIFs in hypoxic regulation of the extracellular matrix:focus on little-known player HIF-3

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BIOCELL 2024年第5期48卷 677-692页

作者： ALEKSANDRA GORNOSTAEVA LUDMILA BURAVKOVA MARGARITA LOBANOVA ELENA ANDREEVA institute of Biomedical problems of the Russian Academy of Sciences Khoroshevskoye Shosse 76AMoscow123007Russia

The structural and associated molecules of the extracellular matrix(ECM)complex is an important component of the local milieu of cells,both for maintaining their functions and homeostasis.It is a dynamic structure that is finely tuned to changes in the microenvironment.One of these factors is hypoxia,which can arise in tissues due to physiological or pathological effects.As a result of the hypoxic effect,the properties of the ECM are significantly modified,stiffness increases,the balance between degradation and synthesis of structural proteins shifts,and the deposition of biologically active mediators’changes.Hypoxia-inducible factors(HIFs)contribute significantly to the modification of the properties of the ECM under hypoxia.Among the three HIF isoforms,HIF-1 is the most studied,with numerous identified target genes encoding proteins that participate in all matrisome compartments.Much less is known about HIF-2 and HIF-3.In the context of the effects of hypoxia on the matrisome,HIF-3 isoform is of particular interest.Unlike the first two isoforms,transiently expressed during the first hours of hypoxia,HIF-3 is activated after around 24 h of exposure to hypoxia and persists for a longer period.In addition,its transcription is more pronounced under hypoxia than are HIFs 1 and 2.HIF-3,rather than the first two isoforms,is possibly responsible for the changes that occur in matrisome during prolonged hypoxic conditions.This review attempts to summarize the available data on the involvement of HIF-3 in the matrisome modification under hypoxia.

关键词： Hypoxia Hypoxia-inducible factors Matrisome

Pulsed THz radiation under ultrafast optical discharge of vacuum photodiode

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Frontiers of Optoelectronics 2024年第2期17卷 99-112页

作者： Aleksandr Ushakov Kseniia Mamaeva Leonid Seleznev Georgy Rizaev Vladimir Bukin Timophey Dolmatov Pavel Chizhov Vladimir Bagdasarov Sergey Garnov Prokhorov General Physics institute of the Russian Academy of Sciences Moscow 119991Russia physical institute Russian Academy of SciencesMoscow 119991Russia Moscow institute of Physics and Technology Dolgoprudny 141700Russia Russian institute for Scientific and Technical Information Moscow 125190Russia

In this paper,we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a vacuum photodiode.We use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kV/cm external electric field for the photo-emitted electron acceleration.Measurements of terahertz pulses energy as a function of emitted charge density,incidence angle of optical radiation and applied electric field have been provided.Spectral and polarization characteristics of generated terahertz pulses have also been studied.The proposed semi-analytical model and simulations in COMSOL Multiphysics prove the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.

关键词： Electron emission Vacuum photodiode Ultrafast excitation Terahertz

Surface modification by ligand growth strategy for dense copper bismuth film as photocathode to enhance hydrogen production activity

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Frontiers in Energy 2024年第1期18卷 89-100页

作者： Zhouzhou WANG Qingwei WU Jieming WANG Ying YU institute of Nanoscience and Nanotechnology College of Physical Science and TechnologyCentral China Normal UniversityWuhan 430079China

Hydrogen production from photoelectrochemical(PEC)water splitting has been regarded as a promising way to utilize renewable and endless solar energy.However,semiconductor film grown on photoelectrode suffers from numerous challenges,leading to the poor PEC performance.Herein,a straightforward sol-gel method with the ligand-induced growth strategy was employed to obtain dense and homogeneous copper bismuthate photocathodes for PEC hydrogen evolution reaction.By various characterizations,it was found that the nucleation and surface growth of CuBi_(2)O_(4)layer induced by 2-methoxyethanol ligand(2-CuBi_(2)O_(4))demonstrated a decent crystallinity and coverage,as well as a large grain size and a low oxygen vacancy concentration,leading to the good ability of light absorption and carrier migration.Consequently,under simulated sunlight irradiation(AM1.5G,100 mW/cm^(2)),the 2-CuBi_(2)O_(4)photocathode achieved an enhanced photocurrent density of−1.34 mA·cm^(−2)at 0.4 V versus the reversible hydrogen electrode and a promising applied bias photon-to-current efficiency of 0.586%.This surface modification by ligand growth strategy will shed light on the future design of advanced photoelectrodes for PEC water splitting.

关键词： copper bismuthate photocathode ligand growth strategy dense film PEC

Needs and challenges of optical atmospheric monitoring on the background of carbon neutrality in China

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Frontiers of Environmental Science & Engineering 2024年第6期18卷 49-62页

作者： Wenqing Liu Chengzhi Xing Anhui institute of Optics and Fine Mechanics Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 23001China

The achievement of the targets of coordinated control of PM2.5 and O3 and the carbon peaking and carbon neutrality depend on the development of pollution and greenhouse gas monitoring technologies.Optical monitoring technology,based on its technical characteristics of high scalability,high sensitivity and wide-targets detection,has obvious advantages in pollution/greenhouse gases monitoring and has become an important direction in the development of environmental monitoring technology.At present,a system of environmental optical monitoring technology with differential optical absorption spectroscopy(DOAS),cavity ring-down spectroscopy(CRDS),light detection and ranging(LIDAR),laser heterodyne spectroscopy(LHS),tunable diode laser absorption spectroscopy(TDLAS),fourier transform infrared spectroscopy(FTIR)and fluorescence assay by gas expansion(FAGE)as the main body has been established.However,with the promotion of“reduction of pollution and carbon emissions”strategy,there have been significant changes in the sources of pollution/greenhouse gases,emission components and emission concentrations,which have put forward new and higher requirements for the development of monitoring technologies.In the future,we should pay more attention to the development of new optical monitoring techniques and the construction of stereoscopic monitoring system,the interdisciplinarity(among mathematics,physics,chemistry and biology,etc.),and the monitoring of greenhouse gases and research on atmospheric chemistry.

关键词： Pollution Greenhouse gas Optical atmospheric monitoring Needs and challenges

Nanofluidic memristor based on the elastic deformation of nanopores with nanoparticle adsorption

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National Science Review 2024年第4期11卷 46-54页

作者： Xi Zhou Yuanyuan Zong Yongchang Wang Miao Sun Deli Shi Wei Wang Guanghua Du Yanbo Xie Department of Chemistry and Chemical Engineering Northwestern Polytechnical University School of physical Science and Technology Northwestern Polytechnical University School of Aeronautics and institute of Extreme Mechanics Northwestern Polytechnical University institute of Modern Physics Chinese Academy of Sciences

The memristor is the building block of neuromorphic computing. We report a new type of nanofluidic memristor based on the principle of elastic strain on polymer nanopores. With nanoparticles absorbed at the wall of a single conical polymer nanopore, we find a pinched hysteresis of the current within a scanning frequency range of 0.01–0.1 Hz, switching to a diode below 0.01 Hz and a resistor above 0.1 Hz. We attribute the current hysteresis to the elastic strain at the tip side of the nanopore, caused by electrical force on the particles adsorbed at the inner wall surface. Our simulation and analytical equations match well with experimental results, with a phase diagram for predicting the system transitions. We demonstrate the plasticity of our nanofluidic memristor to be similar to a biological synapse. Our findings pave a new way for ionic neuromorphic computing using nanofluidic memristors.

关键词： nanofluidics memristor neurocomputing elastic deformation

Cobalt-nanoparticle catalysts derived from zeolitic imidazolate framework@MXene composites for efficient oxidative self-coupling of benzylamines

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Frontiers of Chemical Science and Engineering 2024年第1期18卷 95-106页

作者： Jie Chen Mingyuan Jian Deqiong Xie Kecan Dou Deli Chen Weidong Zhu Fumin Zhang Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Institute of Physical ChemistryZhejiang Normal UniversityJinhua 321004China

In this study,we synthesize a catalyst comprising cobalt nanoparticles supported on MXene by pyrolyzing a composite in a N2 environment.Specifically,the composite comprises a bimetallic Zn/Co zeolitic imidazole framework grown in situ on the outer surface of MXene.The catalytic efficiency of the catalyst is tested for the self-coupling of 4-methoxybenzylamine to produce value-added imine,where atmospheric oxygen(1 atm)is used as the oxidant.Based on the results,the catalyst displayed impressive catalytic activity,achieving 95.4%yield of the desired imine at 383 K for 8 h.Furthermore,the catalyst showed recyclability and tolerance toward benzylamine substrates with various functional groups.The outstanding performance of the catalyst is primarily attributed to the synergetic catalytic effect between the cobalt nanoparticles and MXene support,while also benefiting from the three-dimensional porous structure.Additionally,a preliminary investigation of potential reaction mechanisms is conducted.

关键词： MXene sacrificial template oxidative self-coupling Co nanoparticles imine

Shifting the Paradigm:A Fresh Look at physical Activity Frequency and Its Impact on Mental Health,Life Satisfaction,and Self-Rated Health in Adolescents

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International Journal of Mental Health Promotion 2024年第2期26卷 83-92页

作者： Wenjie Li Yucheng Gao Guoqing Liu Rongkai Hao Meijie Zhang Xiaotian Li Country School of Recreation and Community Sport Capital University of Physical Education and SportsBeijing100191China institute of physical Education and Training Capital University of Physical Education and SportsBeijing100191China

As adolescent mental health problems are becoming a more serious issue globally,this paper explores the relationship of physical activity in adolescents and its frequency on mental health as well as examines the mediating effects of life satisfaction and self-rated health in order to provide a reference for the promotion of mental health in adolescents.A sample of 3578 Chinese high school students completed questionnaires assessing their mental health,physical activity frequency,life satisfaction,and self-rated health.The mean SCL-90 value for adolescents was found to be 1.629%,and 24.73%of adolescents had varying degrees of mental health issue.Increased physical activity frequency is positively associated with improved mental health(pphysical activity frequency and mental health.Specifically,low-frequency physical activity had the most pronounced mediating effect on mental health through life satisfaction,while high-frequency physical activity exerted the most significant mediating effect on mental health through self-rated health.These findings underscore the importance of promoting physical activity among adolescents and highlight the distinct pathways through which physical activity frequency can influence mental health outcomes.Further research is needed to explore these relationships in diverse populations and settings,as well as to develop targeted intervention.

关键词： Adolescents physical activity mental health life satisfaction self-rated health