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Tuning of frictional properties in torsional contact by means of disk grading

Friction 2022年第5期10卷 787-802页

作者： Gianluca COSTAGLIOLA Federico BOSIA Nicola M PUGNO Civil Engineering Institute Ecole Polytechmique Federale de LausamneLausanne 1015Switzerland Department ofApplied Science and Technology Politecnico di TorinoCorso Duca degli Abruzzi 24Torino 10129Italy Laboratory for BioinspiredBionicNanoMeta Materials&MechanicsDepartment of CivilEnvironmental and Mechanical EngineeringUniversity of TrentoTrento 38123Italy School of Engineering and Materials Science Queen Mary University of LondonLondon EI 4NSUK

The contact of two surfaces in relative rotating motion occurs in many practical applications,from mechanical devices to human joints,displaying an intriguing interplay of effects at the onset of sliding due to the axisymmetric stress *** and numerical models have been developed for some typical configurations,but work remains to be done to understand how to modify the emergent friction properties in this *** this paper,we extend the two-dimensional(2D)spring-block model to investigate friction between surfaces in torsional *** investigate how the model describes the behavior of an elastic surface slowly rotating over a rigid substrate,comparing results with analytical calculations based on energy *** show that an appropriate grading of the tribological properties of the surface can be used to avoid a non-uniform transition to sliding due to the axisymmetric configuration.

关键词： friction torsion numerical simulations grading

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Shear instability in heterogeneous nanolayered Cu/Zr composites

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Journal of materials science & Technology 2022年第10期105卷 81-91页

作者： Jianjun Li Feng Qin Dingshun Yan Wenjun Lu Jiahao Yao School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ultrastrong nanolayered metallic composites are usually subjected to low ductility due to plastic instability during *** we investigated the shear instability of a newly designed heterogeneous nanolayered Cu/Zr composites by *** heterogeneity in size was generated by inserting a few thin Cu-Zr bilayers with an individual layer thickness of 2.5-10 nm into the interface region of the Cu/Zr layered composites with an individual layer thickness of 100 *** microindentation tests showed that multiple shear bands appeared in the heterogeneous composite with one bilayer,whereas only a single shear band was formed in that with two or three *** importantly,the layer strain in the multi-shear band region is much smaller than that in the single-shear band *** example,the strain of the 100 nm layers within the shear band in the composite with one 10 nm bilayer could reach as low as 2.8,which was less than half of that in the composite with three 10 nm bilayers,i.e.,*** fndings demonstrated that strain delocalization can be achieved through shear band multiplication if an appropriate number of thin bilayers were used as interlayers in the 100 nm Cu/Zr ***,compared with the homogeneous composite with an individual layer thickness of 100 nm and the bimodal composite which is composed of alternating one 100 nm Cu-Zr bilayer and two 10 nm CuZr bilayers,the heterogeneous composite with one bilayer displayed a higher strength(2.15 GPa)and a favorable resistance to strain localization.

关键词： Nanolayered metallic composites Sputtering Microindentation Shear band Strain delocalization

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Synergistic Tuning of Nickel Cobalt Selenide@Nickel Telluride Core-Shell Heteroarchitectures for Boosting Overall Urea Electrooxidation and Electrochemical Supercapattery

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Energy & Environmental materials 2024年第1期7卷 301-312页

作者： Diab Khalafallah Weibo Huang Mingjia Zhi Zhanglian Hong State Key Laboratory of Silicon Material School of Materials Science and EngineeringZhejiang University38 Zheda RoadHangzhou 310027China Mechanical Design and Materials Department Faculty of Energy EngineeringAswan UniversityP.O.Box 81521AswanEgypt

Herein,we demonstrate the synthesis of bifunctional nickel cobalt selenide@nickel telluride(Ni_(x)Co_(12-x)Se@NiTe)core-shell heterostructures via an electrodeposition approach for overall urea electrolysis and *** 3D vertically orientated NiTe dendritic frameworks induce the homogeneous nucleation of 2D Ni_(x)Co_(12-x)Se nanosheet arrays along similar crystal directions and bring a strong interfacial binding between the integrated active *** particular,the optimized Ni_(6)Co_(6)Se@NiTe with an interface coupling effect works in concert to tune the intrinsic *** only needs a low overpotential of 1.33 V to yield a current density of 10 mA cm^(-2)for alkaline urea ***,the full urea catalysis driven only by Ni_(6)Co_(6)Se@NiTe achieves 10 mA cm^(-2)at a potential of 1.38 V and can approach a constant level of the current response for 40 ***,the integrated Ni_(6)Co_(6)Se@NiTe electrode delivers an enhanced specific capacity(223 mA h g^(-1)at 1 A g^(-1))with a high cycling ***,a hybrid asymmetric supercapacitor(HASC)device based on Ni_(6)Co_(6)Se@NiTe exhibits a favorable rate capability and reaches a high energy density of 67.7 Wh kg^(-1)and a power density of 724.8 W kg^(-1)with an exceptional capacity retention of 92.4%after sequential 12000 cycles at 5 A g^(-1).

关键词： bifunctional Ni_(x)Co_(12-x)Se@NiTe core-shell electrodeposition heterointerfaces supercapacitors UOR

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Hydrogen bonded polymer complex thin films for highly stretchable gas barriers

RSC Applied Polymers

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RSC Applied Polymers 2024年第3期2卷 356-364页

作者： Fisher, Sarah G. Chiang, Hsu-Cheng Iverson, Ethan T. Chang, Edward Grunlan, Jaime C. Department of Chemistry Texas A&M University College Station 77843 TX United States Department of Mechanical Engineering Texas A&M University College Station 77843 TX United States Department of Materials Science & Engineering Texas A&M University College Station 77843 TX United States

Clay-containing polyelectrolyte complexes have been investigated as simple and effective gas barrier coatings for a variety of substrates. Some applications for barrier coatings, such as stretchable electronics, require films that exhibit high extensibility as well as low oxygen transmission rate. This combination of properties is difficult to achieve, as barrier tends to go hand-in-hand with film density. In this work, a stretchable thin film with low oxygen transmission rate (OTR) was prepared through the addition of montmorillonite (MMT) clay into a hydrogen bonded complex of poly(ethylene oxide) (PEO) and poly(acrylic acid) (PAA). Interpolymer hydrogen bonding and MMT clay distribution were found to improve with an increasing ratio of PEO to PAA in the complex, leading to the creation of a highly stretchable coating with a high gas barrier. This elastomeric system, deposited in three steps on 760 μm thick natural rubber, reduces the OTR by two orders of magnitude with a thickness of 1.8 μm. This film maintains a >90% reduction in OTR even after it is subjected to 50% strain. This is believed to be the first gas barrier coating deposited as a buffer-cured, hydrogen bonded polymer complex. © 2024 RSC.

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Electrical Conductivity and Electrochemical Performance of Pr Doped Ceria

Electrical Conductivity and Electrochemical Performance of P...

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243rd ECS Meeting

作者： Dubey, Pawan Kumar Hong, Junsung Lee, Kevin X. Belko, Seraphim Aphale, Ashish Anisur, M.A. Reisert, Michael Singh, Prabhakar Department of Materials Science and Engineering University of Connecticut StorrsCT06269 United States Department of Mechanical Engineering Kennesaw State University MariettaGA30060 United States

ISBN: (纸本)9781607685395

PCO (Praseodymium Cerium Oxide) solid solution (0-50% PrOx) has been prepared by the conventional solid-state ceramic processing route using CeO2 and PrOx powders in the desired stoichiometry and sintering at 1500°C in air. Synthesized powder has been characterized for phase chemistry and lattice structure. Electrochemical characteristics of the synthesized powder has been examined using electrochemical impedance spectroscopy. The observed increase in the electrical conductivity of PCO are associated with increased concentration of oxygen vacancies created by the replacement of Ce4+ ions with Pr+3 ions. The addition of PrOx also lowered the polarization and ohmic losses. © The Electrochemical Society.

关键词： Sintering

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Achieving Near-Intrinsic Exciton Linewidth at Room Temperature in Monolayer WS2 Coupled with a Mie Resonator

Achieving Near-Intrinsic Exciton Linewidth at Room Temperatu...

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CLEO: science and Innovations, S and I 2022

作者： Fang, Jie Yao, Kan Zheng, Yuebing Materials Science & Engineering Program Texas Materials Institute The University of Texas at Austin AustinTX78712 United States Walker Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States

ISBN: (纸本)9781557528209

Strong multiparticle interactions at room temperature (RT) lead to broadened homogeneous exciton linewidths in 2D semiconductors, degrading the quality of excitonic mode and emission. By coupling a Mie resonator with monolayer WS2, we achieve narrowed linewidths at RT, approaching the theoretical limit at 0 Kelvin. © Optica Publishing Group 2022, © 2022 The Author(s)

关键词： Linewidth

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Atomistic dynamics of disconnection-mediated grain boundary plasticity:A case study of gold nanocrystals

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Journal of materials science & Technology 2022年第30期125卷 182-191页

作者： Qi Zhu Haofei Zhou Yingbin Chen Guang Cao Chuang Deng Ze Zhang Jiangwei Wang Center of Electron Microscopy and State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China Wenzhou Key Laboratory of Novel Optoelectronic and Nano Materials Institute of WenzhouZhejiang UniversityWenzhou 325006China Center for X-Mechanics Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China Department of Mechanical Engineering University of ManitobaWinnipegMB R3T 5V6Canada

Grain boundary(GB)mediated deformation is a vital contributor to the plasticity of polycrystalline materials,where the disconnection model has become a widely recognized approach to depict the GB ***,experimental understanding of the atomistic disconnection dynamics remains *** this case study of gold nanocrystals,atomistic disconnection dynamics governing the shear-coupled migration of flat GBs have been systematically investigated via in situ transmission electron microscopy nanomechanical testing supported by molecular dynamics ***,the site-dependent nucleation,shear-driven propagation,and diverse interactions associated with distinct GB disconnections are systematically elucidated and quantitatively ***,the disconnection-mediated GB plasticity proves to prevail among different tilt and mixed GBs in ***,a conceptual map of disconnection-mediated GB dynamics is established,which would furnish a unified understanding of GB plasticity in metallic materials.

关键词： Grain boundaries(GBs) Disconnection dynamics Plastic deformation In situ transmission electron microscopy(TEM) Metallic materials

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Electrochemical hydrogen-storage capacity of graphene can achieve a carbon-hydrogen atomic ratio of 1:1

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science China Chemistry 2022年第2期65卷 318-321页

作者： Quanfeng He Lanping Zeng Lianhuan Han Juan Peng Matthew M.Sartin Yuan-Zhi Tan Dongping Zhan Zhong-Qun Tian State Key Laboratory of Physical Chemistry of Solid Surfaces Fujian Science&Technology Innovation Laboratory for Energy Materials of ChinaEngineering Research Center of Electrochemical Technologies of Ministry of EducationGraphene Industry and Engineering Research InstituteDepartment of ChemistryCollege of Chemistry and Chemical EngineeringDepartment of Mechanical and Electrical EngineeringSchool of Aerospace EngineeringXiamen UniversityXiamen 361005China Department of Chemistry College of Chemistry and Chemical EngineeringNingxia UniversityYinchuan 750021China

As a promising hydrogen-storage material,graphene is expected to have a theoretical capacity of 7.7 wt%,which means a carbon-hydrogen atomic ratio of 1:***,it has not been demonstrated yet by experiment,and the aim of the *** of Energy is to achieve 5.5 wt%in *** designed a spatially-confined electrochemical system and found that the storage capacity of hydrogen adatoms on single layer graphene(SLG)is as high as 7.3 wt%,which indicates a carbon-hydrogen atomic ratio of 1:1 by considering the sp^(3) defects of ***,SLG was deposited on a large-area polycrystalline platinum(Pt)foil by chemical vapor deposition(CVD);then,a micropipette with reference electrode,counter electrode and electrolyte solution inside was impacted on the SLG/Pt foil(the working electrode)to construct the spatially-confined electrochemical *** SLG-uncovered Pt atoms act as the catalytic sites to convert protons(H^(+))to hydrogen adatoms(H_(ad)),which then spill over and are chemically adsorbed on SLG through surface diffusion during the cathodic *** the electrode processes are reversible,the H_(ad) amount can be measured by the anodic stripping *** is the first experimental evidence for the theoretically expected hydrogen-storage capacity on graphene at ambient environment,especially by using H+rather than hydrogen gas(H_(2))as the hydrogen source,which is of significance for the practical utilization of hydrogen energy.

关键词： graphene hydrogen storage surface electrochemistry adsorption desorption spillover surface diffusion

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Lessons Learned from Experimental Tests concerning Liquid Hydrogen Releases 33

Lessons Learned from Experimental Tests concerning Liquid Hy...

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Hazards 33 Process Safety Conference

作者： Tamburini, Federica Ustolin, Federico Salzano, Ernesto Cozzani, Valerio Paltrinieri, Nicola Department of Civil Chemical Environmental and Materials Engineering Alma Mater Studiorum University of Bologna Bologna40131 Italy Department of Mechanical and Industrial Engineering NTNU Norwegian University of Science and Technology Trondheim7034 Norway

In recent years, the adoption of liquid hydrogen (LH2) in industrial and transport applications is becoming increasingly widespread. The high volumetric energy density of LH2 compared to gaseous or compressed hydrogen allows for efficient storage of the fuel. In particular, LH2 is gaining success in the maritime sector because it allows to reduce carbon emissions with respect to fossil fuels and increase the quantity of hydrogen stocked on board. However, the implementation of such emerging technology is still an open issue in terms of safety. Actually, LH2 shares many of the characteristics of liquified natural gas (LNG), both with respect to chemical and physical properties, and to loss of containment scenarios. Therefore, as there is historical evidence of localized explosions (e.g., rapid phase transition (RPT)) in the case of LNG spills on water, the occurrence of severe consequences when LH2 is released onto water must be investigated. In this respect, several large-scale experiments have been performed to analyse the potential consequences of accidental releases of LH2 in or over water. Specifically, more than 80 single spill events have been carried out at release rates of approximately 0.25 kg/s, 0.50 kg/s, and 0.80 kg/s either above or below the water surface with different orientations. The results showed that the RPT phenomenon was not observed. However, the ignition of the released gas cloud with a blast wave overpressure and heat radiation to the surrounding environment was detected. The unexpected ignition of the flammable cloud is not a well-understood event. Few theories have been proposed to explain the reason behind this phenomenon, but, to date, uncertainty is still present. Based on these considerations, in the present paper, the data collected from the experimental campaign have been considered to investigate the relevance of the outcomes in view of their possible use in real applications. A comparison between the experimental set-up and operat

关键词： Fossil fuels

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Design and fabrication of universal resolution targets for microsphere-assisted microscopy 31

Design and fabrication of universal resolution targets for m...

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Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXXI 2024

作者： Abbasian, Vahid Awan, Kashif Masud Darafsheh, Arash Department of Radiation Oncology Washington University School of Medicine in St. Louis St. LouisMO63110 United States Imaging Science Program McKelvey School of Engineering Washington University in St. Louis St. LouisMO63130 United States Institute of Materials Science and Engineering Washington University St. LouisMO63130 United States Department of Mechanical Engineering and Materials Science Washington University in St. Louis St. LouisMO63130 United States

ISBN: (纸本)9781510669550

Determining the achieved spatial resolution in microsphere-assisted microscopy (MAM) has remained an important and challenging task. While fluorescent-based microscopies use fluorescent nano-beads to determine the point spread function (PSF), such a method is not practical in label-free super-resolution techniques. In some previous studies, objects with certain features have been imaged and those feature sizes have been reported as the resolution;however, determining the resolution in that way is not consistent with the definition of resolution based on point sources. Furthermore, the imaging characteristics in MAM may depend on specimen-specific properties, such as materials and substrate. In this study, we propose a robust and objective technique to address these issues. We fabricate arrays of nano-pillars varying in diameter and periodicity, ranging from 50 to 1000 nm. These pillars consist of a 20 nm Ag layer with a 2 nm Cr adhesion layer, deposited on a silicon substrate. The role of specimen-specific properties can be investigated by considering different materials. Fabrication involves the bilayer PMMA resist lift-off process, ensuring accurate deposition of nanometer-scale features to serve as sub-diffraction-limited targets in optical super-resolution microscopy. A deconvolution method that provides a robust platform for resolution measurement was used. By deconvolving the object profile, obtained from scanning electron microscopy, from the image profile, the PSF of the system is determined. Our proposed technique offers a reliable and standardized approach for quantifying resolution, magnification, and field-of-view in MAM or any other label-free microscopy technique, enabling accurate and objective comparison across different novel microscopy techniques. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

关键词： Microspheres

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