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Macro-superlubricity in sputtered MoS_(2)-based films by decreasing edge pinning effect

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Friction 2024年第1期12卷 52-63页

作者： Chunmeng DONG Dong JIANG Yanlong FU Desheng WANG Qinqin WANG Lijun WENG Ming HU Xiaoming GAO Jiayi SUN state Key Laboratory of solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

To date,MoS_(2) can only be achieved at *** pinning effect caused by structure defects is the most obvious barrier to expand the size of structural superlubricity to ***,we plan to pin edge planes of MoS_(2) with nanospheres,and then the incommensurate structure can be formed between adjacent rolling nanoparticles to reduce *** sputtered MoS_(2) film was prepared by the physical vapor deposition(PVD)in *** enough Cu_(2)O nanospheres(~40 nm)were generated in situ at the edge plane of MoS_(2) layers by liquid phase *** incommensurate structure(mismatch angle(θ)=8°)caused by MoS_(2) layers was formed before *** friction coefficient of the films(5 N,1,000 r/min)was~6.0×10^(−3) at the *** friction,MoS_(2) layers pinned on numerous of Cu_(2)O nanoparticles reduced its edge pinning effect and decreased ***,much more incommensurate was formed,developing macro-superlubricity.

关键词： sputtered MoS_(2)film Cu_(2)O nanospheres edge pinning effect macro-superlubricity

Balancing the Quantum Speed Limit and Instantaneous Energy Cost in Adiabatic Quantum Evolution

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Chinese physics Letters 2024年第4期41卷 7-12页

作者：徐建文张宇佳郑文蔡浩阳周浩宇李先科廖绪东张钰李邵雄兰栋谭新生于扬 National Laboratory of solid state Microstructures School of PhysicsNanjing UniversityNanjing 210093China Shishan Laboratory Suzhou Campus of Nanjing UniversitySuzhou 215163China Hefei National Laboratory Hefei 230088China

Adiabatic time-optimal quantum controls are extensively used in quantum technologies to break the constraints imposed by short coherence ***,practically it is crucial to consider the trade-off between the quantum evolution speed and instantaneous energy cost of process because of the constraints in the available control ***,we experimentally show that using a transmon qubit that,even in the presence of vanishing energy gaps,it is possible to reach a highly time-optimal adiabatic quantum driving at low energy cost in the whole evolution *** validates the recently derived general solution of the quantum Zermelo navigation problem,paving the way for energy-efficient quantum control which is usually overlooked in conventional speed-up schemes,including the well-known counter-diabatic *** designing the control Hamiltonian based on the quantum speed limit bound quantified by the changing rate of phase in the interaction picture,we reveal the relationship between the quantum speed limit and instantaneous energy ***,we demonstrate fast and high-fidelity quantum adiabatic processes by employing energy-efficient driving strengths,indicating a promising strategy for expanding the applications of time-optimal quantum controls in superconducting quantum circuits.

关键词： process quantum adiabatic

On the Features of Thermal Convection in a Compressible Gas

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Fluid Dynamics & Materials Processing 2024年第5期20卷 957-974页

作者： Igor B.Palymskiy physics department Siberian State University of Telecommunications and Information SciencesNovosibirsk City630102Russia physics department Siberian State University of Geosystems and TechnologiesNovosibirsk City630108Russia

The fully nonlinear equations of gas dynamics are solved in the framework of a numerical approach in order to study the stability of the steady mode of Rayleigh-Bénard convection in compressible,viscous and heat-conducting gases encapsulated in containers with no-slip boundaries and isothermal top and bottom *** initial linear temperature profile is assumed.A map of the possible convective modes is presented assuming the height of the region and the value of the temperature gradient as influential *** a relatively small height,isobaric convection is found to take place,which is taken over by an adiabatic mode when the height exceeds the critical value,or by a super-adiabatic mode in case of a relatively high temperature *** the adiabatic mode,convective flow develops due to adiabatic processes given a stable initial *** analytic formula for the critical height of the region is derived taking into account and neglecting the dependence of the gas viscosity on the ***,an analytic formula is obtained for the upper boundary of the region of applicability of the Boussinesq approximation for incompressible *** models for compressible gases are relevant to practical situations such as the study of convective flows in spatially extended gas mixtures when dealing with safety issues related to hydrocarbons stored in gas stations.A dangerous situation arises when the tank is almost empty but some hydrocarbon is left at the bottom of the *** the presence of convective flows,the vaporized fuel is mixed with the oxidizer(air)forming a gas-vapor ***,if the volumetric concentration of fuel vapor(hydrocarbon)is in the interval between the lower and upper concentration limits of ignition,then the gas-vapor mixture becomes explosive and any accidental spark is sufficient to cause an emergency.

关键词： Rayleigh-Bénard convection gas stable stratification unstable stratification temperature gradient

Embedded Majorana islands

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Science China(physics,Mechanics & Astronomy) 2024年第9期67卷 154-164页

作者： Jin-Xing Hou Alex Weststrom Rui Wang Wen-Li Yang Jian Li Institute of Modern physics Northwest UniversityXi’an 710127China department of physics School of ScienceWestlake UniversityHangzhou 310030China Shaanxi Key Laboratory for Theoretical physics Frontiers Xi’an 710127China Institute of Natural Sciences Westlake Institute for Advanced StudyHangzhou 310024China National Laboratory of solid state Microstructures and department of physics Nanjing UniversityNanjing 210093China Collaborative Innovation Center for Advanced Microstructures Nanjing 210093China Peng Huanwu Center for Fundamental Theory Xi’an 710127China

Mesoscopic superconducting islands hosting Majorana zero modes(MZMs),or Majorana islands in short,offer a prototype of topological *** this work we investigate theoretically the model of a generic Majorana island tunneling-coupled to a singlepiece metallic substrate,hence an embedded Majorana *** show the crucial consequences of an interplay between the topological ground states nonlocally addressed by the MZMs and the metallic bath with coherent electron propagation:on the one hand,the topological degeneracy on the Majorana island can be preserved,by virtue of the particle-hole symmetry,despite the apparent bath-induced coupling between MZMs;on the other hand,the electronic interference in the metallic bath may lead to profound alterations to the renormalization group behavior of the hybrid system towards low energy/temperature compared with conventional Kondo *** work serves to establish the model of embedded Majorana islands as an experimentally relevant and theoretically intriguing problem particularly in the direction of topological quantum computation.

关键词： topological quantum computation Majorana zero modes topological qubit mesoscopic superconductor topological Kondo effect

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Classification and spectrum optimization method of grease based on infrared spectrum

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Friction 2024年第6期12卷 1154-1164页

作者： Xin FENG Yanqiu XIA Peiyuan XIE Xiaohe LI School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijing 102206China state Key Laboratory of solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

The infrared(IR)absorption spectral data of 63 kinds of lubricating greases containing six different types of thickeners were obtained using the IR *** Kohonen neural network algorithm was used to identify the type of the lubricating *** results show that this machine learning method can effectively eliminate the interference fringes in the IR spectrum,and complete the feature selection and dimensionality reduction of the high-dimensional spectral *** 63 kinds of greases exhibit spatial clustering under certain IR spectrum recognition spectral bands,which are linked to characteristic peaks of lubricating greases and improve the recognition accuracy of these *** model achieved recognition accuracy of 100.00%,96.08%,94.87%,100.00%,and 87.50%for polyurea grease,calcium sulfonate composite grease,aluminum(Al)-based grease,bentonite grease,and lithium-based grease,*** on the different IR absorption spectrum bands produced by each kind of lubricating grease,the three-dimensional spatial distribution map of the lubricating grease drawn also verifies the accuracy of classification while recognizing the *** paper demonstrates fast recognition speed and high accuracy,proving that the Kohonen neural network algorithm has an efficient recognition ability for identifying the types of the lubricating grease.

关键词： grease infrared(IR)spectroscopy layered Kohonen network species recognition spectrum band optimization

Analysis of cerium substitution in Co-Sr based spinel ferrites for high frequency application

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Journal of Rare Earths 2024年第9期42卷 1755-1763,I0005页

作者： Laura Khudaysh Inas A.Ahmed Syeda Rabia Ejaz Sajjad Ahmad Khan Yasir A.Haleem Mohamed M.Ibrahim Mahmood Ali Hafiz Muhammad Tahir Farid Zeinhom M.El-Bahy department of physics Faculty of ScienceJazan UniversityJazan45142Saudi Arabia department of Chemistry Faculty of ScienceKing Khalid UniversityAbha62224Saudi Arabia department of physics The Government Sadiq College Women UniversityBahawalpur63100Pakistan Institute of physics Khwaja Fareed University of Engineering and Information TechnologyRahim Yar Khan64200Pakistan department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Centre of Excellence in solid state physics University of the PunjabLahorePakistan department of physics Government CollegeTaunsa Sharif32200Pakistan department of Chemistry Faculty of ScienceAl-Azhar UniversityNasr City11884CairoEgypt

Spinel ferrites exhibit exceptional magnetic properties,making them a distinctive class of magnetic *** sol-gel technique was utilized for the synthesis of spinel ferrites with the chemical formula Co_(0.6)Sr_(0.4)Ce_(x)Fe_(2-x)O_(4). Following that,a comprehensive X-ray diffraction analysis unveiled the crystalline cubic structure of the synthesized *** the utilization of the M-H loop approach,the ferromagnetic attributes of ferrites were assessed,and the assimilation of rare earth elements led to substantial enhancements in saturation magnetization,remanence,and *** ferrites with a high concentration of rare earth elements have improved direct current resistivity and activation *** logarithm of a material's resistance increased from 5.29 to 8.12 Ω·cm as cerium is *** a change in the amount of cerium,the activation energy goes up from 0.19 to *** changing the frequency from 5.5 to 9.5 GHz,the dielectric characteristics were *** the frequency goes up,the dielectric constant goes *** ferrites that have been made better in every way can be used in high-frequency applications.

关键词： Activation energy DC electrical resistance Remanence magnetization Cobalt strontium spinel ferrites High frequency application Rare earths

Micelle-directed self-assembly of single-crystal-like mesoporous stoichiometric oxides for high-performance lithium storage

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National Science Review 2024年第4期11卷 195-205页

作者： Yanhua Wan Changyao Wang Xingmiao Zhang Yang Yin Mengmeng Liu Bing Ma Linlin Duan Yuzhu Ma Wei Zhang Changlin Zheng Dongliang Chao Fei Wang Yongyao Xia Wei Li department of Chemistry Laboratory of Advanced Materials Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials State Key Laboratory of Molecular Engineering of Polymers College of Chemistry and Materials ScienceFudan University state Key Laboratory of Surface physics and department of physics Fudan University

Due to their uncontrollable assembly and crystallization process,the synthesis of mesoporous metal oxide single crystals remains a formidable ***,we report the synthesis of single-crystal-like mesoporous Li2TiSiO5by using soft micelles as *** key lies in the atomic-scale self-assembly and step-crystallization processes,which ensure the formation of single-crystal-like mesoporous Li2TiSiO5microparticles via an oriented attachment growth mechanism under the confinement of an in-situ formed carbon *** mesoporous Li2TiSiO5anode achieves a superior rate capability(148 mAh g-1at5.0 A g-1) and outstanding long-term cycling stability(138 mAh g-1after 3000 cycles at 2.0 A g-1) for lithium storage as a result of the ultrafast Li+diffusion caused by penetrating mesochannels and nanosized crystal frameworks（5-10 nm）.In comparison,bulk Li2TiSiO5exhibits poor rate capability and cycle performance due to micron-scale diffusion *** method is very simple and reproducible,heralding a new way of designing and synthesizing mesoporous single crystals with controllable frameworks and chemical functionalities.

关键词： mesoporous materials micelles single-crystal-like Li2TiSiO5 lithium-ion batteries

Achieving a remarkable low-temperature tensile ductility in a high-strength tungsten alloy

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Tungsten 2024年第1期6卷 150-161页

作者： Xiang Cheng Zhuo-Ming Xie Xue-Feng Xie Long-Fei Zeng Rui Liu Jun-Feng Yang Xue-Bang Wu Xian-Ping Wang Chang-Song Liu Qiang-Feng Fang Key Laboratory of Materials physics Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China University of Science and Technology of China Hefei 230026China Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou 341000China

Hot-swaging yields a high ultimate tensile strength of 712 MPa but a limited tensile ductility with the total elongation of3.6%at a testing temperature of 200℃in a representative W-0.5wt.%ZrC *** this work,the evolution of Vickers microhardness with annealing temperatures is investigated in detail,which contributes to a rough index chart to guide the search for an optimized post-annealing *** the post-annealing around 1300℃,an outstanding tensile ductility at200℃,including a uniform elongation of 14%and a total elongation of~25%,has been achieved without the sacrifice of its *** evolution of dislocations and grain structures with the annealing temperatures accessed through backscattered scanning electron microscope and transmission electron microscope analysis reveals that the improved low-temperature tensile ductility has resulted from the reduction of residual dislocations and dislocation tanglement via the static recovery,which provides more room to accommodate dislocations,and hence stronger strain hardening ability and tensile ductility.

关键词： Tungsten Low-temperature ductility Annealing Dislocations

In-situ formation of nitrogen doped microporous carbon nanospheres derived from polystyrene as lubricant additives for anti-wear and friction reduction

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Friction 2024年第3期12卷 439-451页

作者： Yixin WANG Qi LU Huijie XIE Shujuan LIU Qian YE Feng ZHOU Weimin LIU state Key Laboratory of solidification Processing Center of Advanced Lubrication and Seal MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China state Key Laboratory of solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

This study presents a nitrogen-doped microporous carbon nanospheres(N@MCNs)prepared by a facile polymerization–carbonization process using low-cost *** N element in situ introduces polystyrene(PS)nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent,and then carbonization obtains N@*** as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric *** friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc *** results showed that N@MCNs exhibit superb reduction performance of friction and *** the addition of N@MCNs was 0.06 wt%,the friction coefficient of PAO-10 decreased from 0.188 to 0.105,and the wear volume reduced by 94.4%.The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%,*** carrying capacity of load was rocketed from 100 to 400 N *** the analysis of the lubrication mechanism,the result manifested that the prepared N@MCNs enter clearance of the friction pair,transform the sliding friction into the mixed friction of sliding and rolling,and repair the contact surface through the repair ***,the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides,which can avert direct contact with the matrix and improve the tribological *** experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing *** preparing method can be ulteriorly expanded to multi-element co-permeable *** and boron co-doped carbon nanospheres(B,N@MCNs)were prepared by mixed carbonization of N-enriched PS and boric acid,and exhibited high load carrying capacity and good tribolog

关键词： lubricant additives hypercrosslinked polystyrene carbon nanospheres friction reduction anti-wear