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Controlled Nanocutting of Graphene

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Nano Research 2008年第2期1卷 116-122页

作者： Lijie Ci Zhiping Xu Lili Wang Wei Gao feng Ding kevin f.kelly Boris I.Yakobson Pulickel M.Ajayan Department of Mechanical Engineering&Materials Science Rice UniversityHouston TX 77005USA Department of Electrical and Computer Engineering Rice UniversityHouston TX 77005USA

Rapid progress in graphene-based applications is calling for new processing techniques for creating graphene components with different shapes,sizes,and edge *** we report a controlled cutting process for graphene sheets,using nickel nanoparticles as a knife that cuts with nanoscale *** cutting proceeds via catalytic hydrogenation of the graphene lattice,and can generate graphene pieces with specifi c zigzag or armchair *** size of the nanoparticle dictates the edge structure that is produced during the *** cutting occurs along straight lines and along symmetry lines,defined by angles of 60ºor 120º,and is defl ected at free edges or defects,allowing practical control of graphene nano-engineering.

关键词： Graphene nano-engineering electronics catalytic hydrogenation

Artificial light at night(ALAN) pollution alters bat lunar chronobiology:insights from broad-scale long-term acoustic monitoring

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Ecological Processes 2024年第01期13卷 176-187页

作者： Han Li Pauline Allen Saige Boris Samantha Lagrama Jade Lyons Christina Mills Pauline Moussi Casey Nichols Carter Tacosik Mc Kenzie Tsaousis Nyzaya Livingston Wilson John f.Grider kevin A.Parker Matina C.Kalcounis-Rueppell Department of Biology University of Nebraska Omaha Department of Biology University of North Carolina Greensboro Colorado Parks and Wild-life Parker Ecology LLC Department of Biological Sciences University of Alberta

Background The timing of behavior and habitat use of nocturnal animals can be influenced by the lunar cycle in nature. The prevalence of artificial light at night(ALAN) has been recognized as a source of environmental pol-lution. The interaction between ALAN and the lunar cycle on bat behavior is important for understanding anthro-pogenic effects on bats. We utilized a decade(2012–2022) of acoustic monitoring data collected in North Carolina, United States, to investigate the relationship between bat activity, lunar cycle, and light pollution. We examined whether the amount of lunar illumination affected species-specific nightly activity and whether hourly bat activity patterns varied between nights with different moon phases. We further investigated if the relationship between bat activity and the lunar cycle might be altered by light *** We found that seven bat species showed activity variation across nights in relation to the amount of moon illumination when ALAN was absent. In general, bats were less active on full moon nights compared to new moon nights. Light pollution interacted with the bat–lunar relationship in five of the seven species, masking the effect of the lunar cycle. We identified delayed bat activity patterns on nights with a full or waxing moon in seven species, and light pollution altered that pattern in four species. Overall, ALAN was associated with decreased bat activity inde-pendent of lunar cycle *** Our study demonstrated that at a broad spatial scale, ALAN negatively affected many North American temperate bat species and altered their lunar chronobiology. As light pollution is spreading to historically dark areas and habitats, ALAN might couple with other threats, such as the white-nose syndrome or climate change, to cause cascading damage in the environment that depends on ecosystem services such as pest control provided by bats. We argue that further research and conservation actions are needed to mitigate

关键词： Artificial light at night ALAN Bats Chiroptera Chronobiology Light pollution Lunar cycle Moonlight

Numerical Study of Semidiscrete Penalty Approach for Stabilizing Boussinesq System with Localized feedback Control

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Annals of Applied Mathematics 2024年第2期40卷 191-218页

作者： Mejdi Azaiez kevin Le Balc'h Universite de Bordeaux Bordeaux-INPI2M UMR5295F-33400TalenceFrance Inria Sorbonne UniversiteUniversite de ParisCNRSLaboratoire Jacques-Louis LionsParisFrance

We investigate the numerical approximation for stabilizing the semidiscrete linearized Boussinesq system around an unstable stationary *** is attained through internal feedback controls applied to the velocity and temperature equations,localized within an arbitrary open *** study follows the framework presented in[14],considering the continuous linearized Boussinesq *** primary objective is to explore the penalizationbased approximation of the free divergence condition in the semidiscrete case and provide a numerical validation of these results in a two-dimensional setting.

关键词： Boussinesq system penalty method stabilization feedback control

Multinuclear MR and MRI study of lithium-ion cells using a variable field magnet and a fixed frequency Rf probe

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Magnetic Resonance Letters 2024年第1期4卷 10-20页

作者： Andrés Ramírez Aguilera florin Marica kevin J.Sanders Md Al Raihan C.Adam Dyker Gillian R.Goward Bruce *** UNB MRI Centre Department of PhysicsUniversity of New BrunswickFrederictonNew BrunswickE3B 5A3Canada Department of Chemistry McMaster UniversityHamiltonOntarioL8S 4L8Canada Department of Chemistry University of New BrunswickFrederictonNew BrunswickE3B 5A3Canada

An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)f,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(Rf)probe was employed in the *** magnetic field was changed to set the resonance frequency of each nucleus to the fixed Rf probe frequency of 33.7 *** cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were *** cell was pristine,and one was charged to a cell voltage of 4.2 *** results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion *** methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.

关键词： Multinuclear MR/MRI Variable field magnet Lithium-ion battery Parallel-plate rf probe

Interfacial engineering through lead binding using crown ethers in perovskite solar cells

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Journal of Energy Chemistry 2024年第5期92卷 263-270页

作者： Sun-Ju Kim YeonJu Kim Ramesh Kumar Chitumalla Gayoung Ham Thanh-Danh Nguyen Joonkyung Jang Hyojung Cha Jovana Milić Jun-Ho Yum kevin Sivula Ji-Youn Seo Department of Nano fusion Technology Pusan National UniversityBusan 46241Republic of Korea Laboratory for Molecular Engineering of Optoelectronic Nanomaterials Institute of Chemical Sciences and EngineeringÉcole Polytechnique Fédérale de Lausanne(EPFL)1015 LausanneSwitzerland Department of Energy Convergence and Climate Change Kyungpook National UniversityDaegu 41566Republic of Korea Department of Hydrogen and Renewable Energy Kyungpook National UniversityDaegu 41566Republic of Korea Adolphe Merkle Institute University of FribourgCH-1700 FribourgSwitzerland

In the domain of perovskite solar cells(PSCs),the imperative to reconcile impressive photovoltaic performance with lead-related issue and environmental stability has driven innovative *** study pioneers an approach that not only rectifies lead leakage but also places paramount importance on the attainment of rigorous interfacial *** ethers,notably benzo-18-crown-6-ether(B18C6),were strategically integrated at the perovskite-hole transport material *** ethers exhibit a dual role:efficiently sequestering and immobilizing Pb^(2+)ions through host-guest complexation and simultaneously establishing a robust interfacial passivation *** crown ether candidates,guided by density functional theory(DfT)calculations,demonstrated proficiency in binding Pb2+ions and optimizing interfacial *** devices incorporating these materials achieved exceptional power conversion efficiency(PCE),notably 21.7%for B18C6,underscoring their efficacy in lead binding and interfacial *** techniques,including time-of-flight secondary ion mass spectrometry(Tof-SIMS),ultraviolet photoelectron spectroscopy(UPS),time-resolved photoluminescence(TRPL),and transient absorption spectroscopy(TAS),unequivocally affirmed Pb^(2+)ion capture and suppression of non-radiative ***,these PSCs maintained efficiency even after enduring 300 h of exposure to 85%relative *** research underscores the transformative potential of crown ethers,simultaneously addressing lead binding and stringent interfacial passivation for sustainable PSCs poised to commercialize and advance renewable energy applications.

关键词： Perovskite solar cells Interfacial passivation Crown ether materials Stability

Dynamics of self-hybridized exciton–polaritons in 2D halide perovskites

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Light(Science & Applications) 2024年第1期13卷 13-22页

作者： Surendra B.Anantharaman Jason Lynch Christopher E.Stevens Christopher Munley Chentao Li Jin Hou Hao Zhang Andrew Torma Thomas Darlington francis Coen kevin Li Arka Majumdar PJames Schuck Aditya Mohite Hayk Harutyunyan Joshua R.Hendrickson Deep Jariwala Department of Electrical and Systems Engineering University of PennsylvaniaPhiladelphiaPA19104USA KBR Inc. BeavercreekOH45431USA Air force Research Laboratory Sensors DirectorateWright-Patterson Air Force BaseOH45433USA Department of Physics University of WashingtonSeattleWA98195USA Department of Physics Emory UniversityAtlantaGA30322USA Department of Chemical and Biomolecular Engineering Rice UniversityHoustonTX77005USA Department of Materials Science and Nanoengineering Rice UniversityHoustonTX77005USA Applied Physics Program Smalley‐Curl InstituteRice UniversityHoustonTX77005USA Department of Mechanical Engineering Columbia UniversityNew YorkNY10027USA Department of Electrical and Computer Engineering University of WashingtonSeattleWA98195USA

Excitons,bound electron–hole pairs,in two-dimensional hybrid organic inorganic perovskites(2D HOIPs)are capable of forming hybrid light-matter states known as exciton-polaritons(E–Ps)when the excitonic medium is confined in an optical *** the case of 2D HOIPs,they can self-hybridize into E–Ps at specific thicknesses of the HOIP crystals that form a resonant optical cavity with the ***,the fundamental properties of these self-hybridized E–Ps in 2D HOIPs,including their role in ultrafast energy and/or charge transfer at interfaces,remain ***,we demonstrate that>0.5µm thick 2D HOIP crystals on Au substrates are capable of supporting multiple-orders of self-hybridized E–P *** E–Ps have high Q factors(>100)and modulate the optical dispersion for the crystal to enhance sub-gap absorption and *** varying excitation energy and ultrafast measurements,we also confirm energy transfer from higher energy E–Ps to lower energy E–***,we also demonstrate that E–Ps are capable of charge transport and transfer at *** findings provide new insights into charge and energy transfer in E–Ps opening new opportunities towards their manipulation for polaritonic devices.

关键词： charge polar excitation

Prediction of Weyl semimetal and antiferromagnetic topological insulator phases in Bi_(2)MnSe_(4)

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npj Computational Materials 2019年第1期5卷 867-873页

作者： Sugata Chowdhury kevin f.Garrity francesca Tavazza Materials Measurement Laboratory National Institute for Standards and TechnologyGaithersburgMD 20899USA

Three-dimensional materials with strong spin–orbit coupling and magnetic interactions represent an opportunity to realize a variety of rare and potentially useful topological phases with broken time-reversal *** this work,we use first principles calculations to show that the recently synthesized material Bi_(2)MnSe_(4) displays a combination of spin–orbit-induced band inversion,also observed in non-magnetic topological insulator Bi2PbSe4,with magnetic interactions,leading to several topological *** bulk form,the ferromagnetic phase of Bi_(2)MnSe_(4) has symmetry protected band crossings at the fermi level,leading to either a nodal line or Weyl semimetal,depending on the direction of the *** to the combination of time reversal symmetry plus a partial translation,the ground state layered antiferromagnetic phase is instead an antiferromagnetic topological *** surface of this phase intrinsically breaks time-reversal symmetry,allowing the observation of the half-integer quantum anomalous Hall ***,we show that in thin film form,for sufficiently thick slabs,Bi_(2)MnSe_(4) becomes a Chern insulator with a band gap of up to 58 *** combination of properties in a stoichiometric magnetic material makes Bi_(2)MnSe_(4) an excellent candidate for displaying robust topological behavior.

关键词： topological insulator symmetry

Controlling light with light using coherent metadevices: all-optical transistor, summator and invertor

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Light(Science & Applications) 2015年第1期4卷 360-366页

作者： Xu fang kevin f MacDonald Nikolay I Zheludev Optoelectronics Research Centre&Centre for Photonic Metamaterials University of Southampton SO171BJUK Centre for Disruptive Photonic Technologies TPINanyang Technological UniversitySingapore 637371Singapore

Although vast amounts of information are conveyed by photons in optical fibers,the majority of data processing is performed electronically,creating the infamous‘information bottleneck’and consuming energy at an increasingly unsustainable *** potential for photonic devices to directly manipulate light remains unfulfilled due largely to a lack of materials with strong,fast optical *** this paper,we show that small-signal amplifier,summator and invertor functions for optical signals may be realized using a four-port device that exploits the coherent interaction of beams on a planar plasmonic metamaterial,assuming no intrinsic *** redistribution of energy among ports can provide nonlinear input-output signal dependencies and may be coherently controlled at very low intensity levels,with multi-THz bandwidth and without introducing signal distortion,thereby presenting powerful opportunities for novel optical data processing architectures,complexity oracles and the locally coherent networks that are becoming part of the mainstream telecommunications agenda.

关键词： all-optical data processing coherent control photonic metamaterials

Investigation on the effectiveness of pretreatment in stormwater management technologies

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Journal of Environmental Sciences 2014年第9期26卷 1824-1830页

作者： Marla C.Maniquiz-Redillas franz kevin f.Geronimo Lee-Hyung Kim Dept.of Civil and Environmental Engineering Kongju National UniversityCheonanChungnamdoSouth Korea

The effectiveness of presettling basins as component of stormwater best management practice （BMP） technologies was investigated. Storm event monitoring and sediment collection were conducted from May 2009 to November 2012 on the presettling basins of the three BMP technologies designed to capture and treat stormwater runoff from highly impervious roads and parking lots. Data on captured runoff and sediment, total suspended solids （TSS） loadings, rainfall and runoff rate, sediment accumulation rate, as well as particle distribution and pollutant concentrations of sediment were gathered and analyzed along with the physical design characteristics of the presettling basins such as surface area and storage volume. Regression models were generated to determine significant relationships between design parameters. Results revealed that the storage volume ratio （ratio of storage volume of presettling basin to BMP） was an important parameter in designing the presettling basin of the BMP. for practicality, optimizing the design of the presetfling basin means that the storage volume ratio should be determined based on the desired captured amount of runoff and sediment from runoff to limit the frequency of maintenance caused by the accumulation of sediment. It was recommended that pretreatment of runoff should be employed when the site in which the BMP is to be sited has high TSS loading and runoff rate, and is subjected to high intensity rainfall.

关键词： Best management practicePresettling basinPretreatmentSedimentStormwater runoff