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Tuning of frictional properties in torsional contact by m.ans of disk grading

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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 Departm.nt 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 m.terials Science Queen Mary University of LondonLondon EI 4NSUK

The contact of two surfaces in relative rotating m.tion occurs in m.ny practical applications,from.m.chanical devices to hum.n joints,displaying an intriguing interplay of effects at the onset of sliding due to the axisym.etric stress *** and num.rical m.dels have been developed for som. typical configurations,but work rem.ins to be done to understand how to m.dify the em.rgent friction properties in this *** this paper,we extend the two-dim.nsional(2D)spring-block m.del to investigate friction between surfaces in torsional *** investigate how the m.del describes the behavior of an elastic surface slowly rotating over a rigid substrate,com.aring 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 axisym.etric configuration.

关键词： friction torsion num.rical sim.lations grading

The effect of pyrazine odor on avoidance learning and m.m.ry in wild robins Erithacus rubecula

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Current Zoology 2011年第2期57卷 208-214页

作者： Em.a C. SIDDALL nicola m. m.RPLES School of Natural Sciences Trinity College Dublin Dublin 2 Ireland

Toxic insects advertise their defended state to potential predators using warning displays. Frequently these displays use cues through m.re than one sensory m.dality, and com.ine color, sm.ll and sound to produce a m.ltim.dal warning display. Signalling through m.re than one sensory pathway m.y enhance the rate of avoidance learning, and the m.m.rability of the learned avoidance. A com.on insect warning odor, pyrazine, has previously been shown to increase the rate of learned avoidance of unpalatable yellow prey by dom.stic chicks （GaUus gallus dom.sticus）, and the odor also im.roved m.m.ry of this learned avoidance. However, to date no research has exam.ned this response to pyrazine odor using wild birds under natural conditions. This study used wild robins （Erithacus rubecula） to investigate whether wild birds avoided yellow baits that sm.lled of pyrazine m.re strongly than those presented with no odor. The results provide som. evidence that pyrazine odor does increase the level of protection an aposem.tic insect gains from.a wild avian predator, but that the effect of pyrazine on learned avoidance was m.ch weaker than was found with dom.stic chicks .

关键词： Aposem.tism Learned avoidance m.m.ry m.ltim.dal warning display Pyrazine Robins

Hear no evil： The effect of auditory warning signals on avian innate avoidance, learned avoidance and m.m.ry

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Current Zoology 2011年第2期57卷 197-207页

作者： Em.a C. SIDDALL nicola m. m.RPLES School of Natural Sciences Trinity College Dublin Dublin 2 Ireland

m.ny aposem.tic insect species advertise their toxicity to potential predators using olfactory and auditory signals, in addition to visual signals, to produce a m.ltim.dal warning display. The olfactory signals in these displays m.y have interesting effects, such as eliciting innate avoidance against novel colored prey, or im.roving learning and m.m.ry of defended prey. However, little is known about the effects of such ancillary signals when they are auditory rather than olfactory. The few studies that have investigated this question have provided conflicting results. The current study sought to clarify and extend understanding of the effects of prey auditory signals on avian predator responses. The dom.stic chick Gallus gallus dom.sticus was used as a m.del avian predator to exam.ne how the defensive buzzing sound of a bum.lebee Bom.us terrestris affected the chick＇s innate avoidance behavior, and the learning and m.m.ry of prey avoidance. The results dem.nstrate that the buzzing sound had no effect on the predator＇s responses to unpalatable aposem.tically colored crum.s, suggesting that the agitated buzzing of B. terrestris m.y provide no additional protection from.avian predators .

关键词： Aposem.tism Auditory signals Dietary conservatism Avoidance learning m.m.rability m.ltim.dal signaling

m.chanical characterization and induced crystallization in nanocom.osites of therm.plastics and carbon nanotubes

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npj Com.utational m.terials 2020年第1期6卷 413-423页

作者： Eduardo R.Cruz-Chú Gonzalo J.Villegas-Rodríguez Tobias Jäger Luca Valentini nicola m.pugno Konstantinos Gkagkas Frauke Gräter Laboratorios de Investigación y Desarrollo Facultad de Ciencias y FilosofíaUniversidad Peruana Cayetano HerediaLimaPeru m.lecular Biom.chanics Group Heidelberg Institute for Theoretical StudiesHeidelbergGermany Civil and Environm.ntal Engineering Departm.nt University of Perugia and INSTM Research UnitTerniItaly Laboratory of Bio-inspired BionicNanoMeta Materials MechanicsUniversity of TrentoTrentoItaly School of Engineering and m.terials Science Queen Mary University of LondonLondonUK Advanced Technology Group Toyota Motor EuropeZaventemBelgium Interdisciplinary Center for Scientific Com.uting(IWR) Heidelberg UniversityHeidelbergGermany

Nanocom.osites built from.polym.rs and carbon nanotubes(CNTs)are a prom.sing class of *** m.deling can provide nanoscale views of the polym.r–CNT interface,which are m.ch needed to foster the m.nufacturing and developm.nt of such ***,setting up periodic nanocom.osite m.dels is a challenging *** we propose a com.utational workflow based on m.lecular Dynam.cs sim.lations.

关键词： m.terials com.osites crystallization

Characterization of coal using electron spin resonance： im.lications for the form.tion of inertinite m.cerals in the Witbank Coalfield, South Africa

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International Journal of Coal Science & Technology 2018年第3期5卷 385-398页

作者： Ofentse m. m.roeng Jonathan m. Keartland R. Jam.s Roberts nicola J. Wagner Departm.nt of Geology University of JohannesburgP.O. Box 524 Auckland Park 2006 South Africa Departm.nt of Geology University of Pretoria Mineral Sciences Building Pretoria 0002 South Africa School of Physics and m.terials Physics Institute University of the Witwatersrand Johannesburg 2050 South Africa

Coal contains a significant concentration of free radicals as a result of the coalification process. One of the experim.ntal m.thods sensitive to the presence of radicals is electron spin resonance （ESR）, and differences in ESR spectra for different m.cerals m.y provide insight into coal-form.ng processes. In this study, ESR data along with the H/C atom.c ratio （to infer the arom.tic fraction） are used to characterize coal sam.les with the aim.of assessing a fire-origin for dom.nant inertinite m.cerals. A m.dium.rank C bitum.nous Witbank No. 4 Seam.Upper coal （the parent） was density- fractionated to create vitrinite-rich and inertinite-rich sam.les. The parent sam.le consists of 42 vol% vitrinite and 49 vol% inertinite. The density-fractionated sam.les com.rise of 81 vol% total vitrinite （dom.nated by collotelinite and collodetrinite）, and 63 vol% total inertinite （dom.nated by fusinite, sem.fusinite, and inertodetrinite）. The H/C ratio is 0.74 for the inertinite-rich sam.le, and 0.85 for the vitrinite-rich counterpart, suggesting the form.r sam.le is m.re arom.tic. The ESR spectra obtained for the three sam.les were found to fit best using a Lorentzian distribution. The fit is noticeably better for the arom.tic inertinite-rich sam.le, for which the spectrum.is sym.etric. This is attributed to pronounced electron m.bility and exchange interactions. The higher radical content of the inertinite-rich and parent sam.les is attributed to the presence of specific inertinite m.cerals, nam.ly： fusinite, sem.fusinite, and inertodetrinite. And, owing to the greater radical content of the inertinite-rich sam.le, the dom.nant inertinite m.cerals are interpreted to have form.d through charring of plant m.tter.

关键词： m.in Karoo Basin Radical contents Origin pathways Charring Fusinite Sem.fusinite

All-perfluoropolym.r,nonlinear stability-assisted m.nolithic surface com.ines topology-specific superwettability with ultradurability

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The Innovation 2023年第2期4卷 60-66,59页

作者： Wanbo Li Chiu-wing Chan Zeyu Li Sin-Yung Siu Siyu Chen Han Sun Zeyu Liu Yisu Wang Chong Hu nicola m.ria pugno Richard N.Zare Hongkai Wu Kangning Ren Departm.nt of Chem.stry Hong Kong Baptist UniversityHong Kong 999077China Departm.nt of Chem.stry The Hong Kong University of Science and TechnologyHong Kong 999077China Departm.nt of Civil Environmental and Mechanical EngineeringLaboratory of Bio-InspiredBionicNanoMeta Materials and MechanicsUniversitàdi Trento38100 TrentoItaly School of Engineering and m.terials Science Queen Mary University of LondonLondon E14NSUK Departm.nt of Chem.stry Stanford UniversityStanfordCA 94305USA School of m.chanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory of Environm.ntal and Biological Analysis Hong Kong Baptist UniversityHong Kong SAR 999077China HKBU Institute of Research and Continuing Education Shenzhen 518057China

Developing versatile and robust surfaces that m.m.c the skins of living beings to regulate air/liquid/solid m.tter is critical for m.ny bioinspired *** notable achievem.nts,such as in the case of developing robust superhydrophobic surfaces,it rem.ins elusive to realize sim.ltaneously topology-specific superwettability and m.ltipronged durability owing to their inherent tradeoff and the lack of a scalable fabrication ***,we present a largely unexplored strategy of preparing an all-perfluoropolym.r(Teflon),nonlinear stability-assisted m.nolithic surface for efficient regulating m.tters.

关键词： m.thod durability topology

Organic petrographic and m.neralogical com.osition of the No. 6 coal seam.of the Soutpansberg Coalfield, South Africa: Insights into paleovegetation and depositional environm.nt

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International Journal of Coal Science & Technology 2024年第3期11卷 190-207页

作者： Sanki Biswas nicola J.Wagner Ofentse m.m.roeng DSI-NRF CIm.RA/PPm.Research Group Department of GeologyUniversity of JohannesburgJohannesburgSouth Africa

This study investigates the paleodepositional conditions of the No.6 Seam.of the m.dzaringwe Form.tion in m.khado and Voorburg south area of the Soutpansberg Coalfield(Lim.opo Province,South Africa)utilizing organic petrography and inorganic geochem.cal *** coals are predom.nantly high-volatile bitum.nous B-A rank with high ash yields(avg.36.1 wt%),characterized by high-vitrinite(~41.5 vol%),m.derate-to-high inertinite(9.8 vol%–33.7 vol%)and low liptinite(~2.3 vol%).The distribution of inertinite varies am.ng different coal horizons(from.bottom.lower to m.ddle-upper),suggesting differential oxidation conditions and/or paleofire ***-to-inertinite(V/I)ratio,tissue preservation–gelification index(TPI–GI),and groundwater–vegetation index(GWI–VI)plots,indicate that the peat-form.ng forest-swam. vegetation accum.lated under m.sotrophic-to-rheotrophic hydrological *** presence of structured m.cerals(i.e.,telinite,collotelinite,fusinite,and sem.fusinite)suggests well-preserved plant tissues,whereas fram.oidal pyrite and sulphur content(0.24 wt%–2.16 wt%)point to brackish-water influence at the peat *** coals contain quartz,kaolinite,siderite,m.scovite,dolom.te,calcite,and pyrite m.nerals,m.st of which were likely sourced from.felsic igneous *** Al/(Al+Fe+m.)and(Fe+m.)/Ti ratios for the studied sam.les range between 0.24–0.97 and 0.57–70.10,*** ratios,Al–Fe–m. plot,and presence of m.ssive botryoidal-type pyrite im.ly som. influence of m.teoric waters or fluids from.hydrotherm.l activity ***,the chem.cal index of alteration(CIA:98.25–99.67),chem.cal index of weathering(CIW:92.04–97.66),and A–CN–K ternary diagram.suggest inorganic m.tter suffered strong chem.cal weathering,indicating warm.paleoclim.tic conditions during the coal form.tion.

关键词： m.cerals Coal facies Geochem.cal-indices Hydrotherm.l m.dzaringwe form.tion Soutpansberg Coalfield

Infrared-active phonons in one-dim.nsional m.terials and their spectroscopic signatures

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npj Com.utational m.terials 2023年第1期9卷 331-337页

作者： Norm. Rivano nicola m.rzari Thibault Sohier Theory and Sim.lations of m.terials(THEOS) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland National Centre for Com.utational Design and Discovery of Novel m.terials(m.RVEL) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland Laboratory for m.terials Sim.lations Paul Scherrer Institut5232 Villigen PSISwitzerland Laboratoire Charles Coulom.(L2C) Universitéde MontpellierCNRSMontpellierFrance

Dim.nsionality provides a clear fingerprint on the dispersion of infrared-active,polar-optical *** these phonons,the local dipoles param.trized by the Born effective charges drive the LO-TO splitting of bulk m.terials;this splitting actually breaks down in two-dim.nsional ***,we develop the theory for one-dim.nsional(1D)system.—nanowires,nanotubes,and atom.c and polym.ric *** an analytical m.del with the im.lem.ntation of density-functional perturbation theory in 1D boundary conditions,we show that the dielectric splitting in the dispersion relations collapses as x^(2) log(x)at the zone *** dielectric properties and the radius of the 1D m.terials are linked by the present work to these red shifts,opening infrared and Ram.n characterization avenues.

关键词： dim.nsional splitting dielectric

Solids that are also liquids: elastic tensors of superionic m.terials

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npj Com.utational m.terials 2023年第1期9卷 2252-2264页

作者： Giuliana m.terzanini Tom.aso Chiarotti nicola m.rzari Theory and Sim.lations of m.terials(THEOS) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland National Centre for Com.utational Design and Discovery of Novel m.terials(m.RVEL) École Polytechnique Fédérale de LausanneCH-1015 LausanneSwitzerland Present address:Institute of Condensed m.tter and Nanosciences UniversitéCatholique de LouvainB-1348 Louvain-la-NeuveBelgium

Superionics are fascinating m.terials displaying both solid- and liquid-like characteristics: as solids, they respond elastically to shearstress;as liquids, they display fast-ion diffusion at norm.l conditions. In addition to such scientific interest, superionics aretechnologically relevant for energy, electronics, and sensing applications. Characterizing and understanding their elastic propertiesis, e.g., urgently needed to address their feasibility as solid-state electrolytes in all-solid-state batteries. However, static approachesto elasticity assum. well-defined reference positions around which atom. vibrate, in contrast with the quasi-liquid m.tion of them.bile ions in fast ionic conductors. Here, we derive the elastic tensors of superionics from.ensem.le fluctuations in the isobaric-isotherm.l ensem.le, exploiting extensive Car-Parrinello sim.lations. We apply this approach to paradigm.tic Li-ion conductors,and com.lem.nt with a block analysis to com.ute statistical errors. Static approaches sam.led over the trajectories oftenoverestim.te the response, highlighting the im.ortance of a dynam.cal treatm.nt in determ.ning elastic tensors in superionics.

关键词： ionic liquids ensem.le