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Nonlinear dielectric optomechanical metamaterials

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Light(Science & Applications) 2013年第1期2卷 85-89页

作者： Jianfa Zhang kevin f macdonald Nikolay I Zheludev Optoelectronics Research Centre&Centre for Photonic Metamaterials University of SouthamptonSO171BJUK Centre for Disruptive Photonic Technologies Nanyang Technological UniversitySingapore 637371

We introduce a dielectric photonic metamaterial presenting a giant nonlinear optical response driven by resonant optomechanical *** inherently free of Joule losses,it exhibits optical bistability at intensity levels of less than 0.2 mW mm22 and,furthermore,manifests nonlinear asymmetric transmission with a forward:backward optical extinction ratio of more than 30 dB.

关键词： Metamaterial optical bistability optomechanical

Controlling light-with-light without nonlinearity

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Light(Science & Applications) 2012年第1期1卷 87-91页

作者： Jianfa Zhang kevin f macdonald Nikolay I Zheludev Optoelectronics Research Centre&Centre for Photonic Metamaterials University of SouthamptonSouthamptonHampshire SO171BJUK

According to the fundamental Huygens superposition principle,light beams traveling in a linear medium will pass though one another without mutual ***,the field of photonics is based on the premise that controlling light signals with light requires intense laser fields to facilitate beam interactions in nonlinear media,where the superposition principle can be *** we challenge this wisdom and demonstrate that two coherent beams of light of arbitrarily low intensity can interact on a metamaterial layer of nanoscale thickness in such a way that one beam modulates the intensity of the *** show that the interference of beams can eliminate the plasmonic Joule losses of light energy in the metamaterial or,in contrast,can lead to almost total absorption of *** of this phenomenon may lie in ultrafast all-optical pulse-recovery devices,coherence filters and terahertz-bandwidth light-by-light modulators.

关键词： all-optical metamaterial plasmonic

Sodium and water perturbations in patients who had an acute stroke:clinical relevance and management strategies for the neurologist

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Stroke & Vascular Neurology 2022年第3期7卷 258-266页

作者： kevin C J Yuen Valerie Sharf Elizabeth Smith Minhwan Kim Alissya S M Yuen Paul R macdonald Departments of Neuroendocrinology and Neurosurgery Barrow Neurological InstitutePhoenixArizonaUSA University of Arizona College of Medicine and Creighton School of Medicine PhoenixArizonaUSA Department of Neurology Barrow Neurological InstitutePhoenixArizonaUSA Midwestern University GlendaleIllinoisUSA Creighton University School of Medicine PhoenixArizonaUSA University of California Davis DavisCaliforniaUSA

Sodium and water perturbations,manifesting as hyponatraemia and hypernatraemia,are common in patients who had an acute stroke,and are associated with worse outcomes and increased *** non-stroke related causes of sodium and water perturbations in these patients include underlying comorbidities and concomitant ***,hospitalised patients who had an acute stroke may receive excessive intravenous hypotonic solutions,have poor fluid intake due to impaired neurocognition and consciousness,may develop sepsis or are administered drugs(eg,mannitol);factors that can further alter serum sodium *** and water perturbations can also be exacerbated by the development of endocrine consequences after an acute stroke,including secondary adrenal insufficiency,syndrome of inappropriate antidiuretic hormone secretion and diabetes ***,COVID-19 infection has been reported to increase the risk of development of sodium and water perturbations that may further worsen the outcomes of patients who had an acute *** there are currently no accepted consensus guidelines on the management of sodium and water perturbations in patients who had an acute stroke,we conducted a systematic review of the literature published in English and in peer-reviewed journals between January 2000 and December 2020,according to PRISMA guidelines,to assess on the current knowledge and clinical practices of this *** this review,we discuss the signs and symptoms of hyponatraemia and hypernatraemia,the pathogenesis of hyponatraemia and hypernatraemia,their clinical relevance,and we provide our recommendations for effective treatment strategies for the neurologist in the management of sodium and water perturbations in commonly encountered aetiologies of patients who had an acute stroke.

关键词： patients impaired consequences

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

Inflammasome links traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease

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Neural Regeneration Research 2025年第6期20卷 1644-1664页

作者： Gabriela Seplovich Yazan Bouchi Juan Pablo de Rivero Vaccari Jennifer C.Munoz Pareja Andrew Reisner Laura Blackwell Yehia Mechref kevin K.Wang J.Adrian Tyndall Binu Tharakan firas Kobeissy Department of Surgery Morehouse School of MedicineAtlantaGAUSA Department of Neurobiology Center for NeurotraumaMultiomics&Biomarkers(CNMB)Neuroscience InstituteMorehouse School of MedicineAtlantaGAUSA Department of Neurological Surgery and the Miami Project to Cure Paralysis University of Miami Miller School of MedicineMiamiFLUSA Division of Pediatric Critical Care Department of PediatricsUniversity of Miami Miller School of MedicineMiamiFLUSA Department of Pediatrics Emory UniversityAtlantaGAUSA Department of Neurosurgery Children’s Healthcare of AtlantaAtlantaGAUSA Department of Chemistry and Biochemistry Texas Tech UniversityLubbockTXUSA Morehouse School of Medicine AtlantaGAUSA

Traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease are three distinct neurological disorders that share common pathophysiological mechanisms involving neuroinflammation. One sequela of neuroinflammation includes the pathologic hyperphosphorylation of tau protein, an endogenous microtubule-associated protein that protects the integrity of neuronal cytoskeletons. Tau hyperphosphorylation results in protein misfolding and subsequent accumulation of tau tangles forming neurotoxic aggregates. These misfolded proteins are characteristic of traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease and can lead to downstream neuroinflammatory processes, including assembly and activation of the inflammasome complex. Inflammasomes refer to a family of multimeric protein units that, upon activation, release a cascade of signaling molecules resulting in caspase-induced cell death and inflammation mediated by the release of interleukin-1β cytokine. One specific inflammasome, the NOD-like receptor protein 3, has been proposed to be a key regulator of tau phosphorylation where it has been shown that prolonged NOD-like receptor protein 3 activation acts as a causal factor in pathological tau accumulation and spreading. This review begins by describing the epidemiology and pathophysiology of traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease. Next, we highlight neuroinflammation as an overriding theme and discuss the role of the NOD-like receptor protein 3 inflammasome in the formation of tau deposits and how such tauopathic entities spread throughout the brain. We then propose a novel framework linking traumatic brain injury, chronic traumatic encephalopathy, and Alzheimer's disease as inflammasomedependent pathologies that exist along a temporal continuum. finally, we discuss potential therapeutic targets that may intercept this pathway and ultimately minimize long-term neurological decline.

关键词： Alzheimer's disease caspase-1 chronic traumatic encephalopathy inflammasomes neurodegeneration neuroinflammation NLRP1 NLRP3 pyroptosis tauopathy traumatic brain injury

A thermodynamic perspective on electrode poisoning in solid oxide fuel cells

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1449-1455页

作者： kevin Huang Department of Mechanical Engineering University of South CarolinaColumbiaUSA

A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell(SOfC)technology is the insuf-ficient stack lifespan caused by a variety of degradation mechanisms,which are associated with cell components and chemical *** components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions,whereas the latter regards impurities in feedstocks of oxidant(air)and reductant(fuel).This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in *** discussion focuses on using thermodynamic ana-lysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr,CO_(2),H_(2)O,and SO_(2) and in the anode by species such as S(or H_(2)S),SiO_(2),and P_(2)(or PH_(3)).The author hopes the presented fundamental insights can provide a theoretical foundation for search-ing for better technical solutions to address the critical degradation challenges.

关键词： impurities air fuel reaction activity

Mixed ion and electron transport theory and application in solid oxide conductors

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International Journal of Minerals,Metallurgy and Materials 2022年第4期29卷 870-875页

作者： kevin Huang Department of Mechanical engineering University of South CarolinaColumbiaSC 292201USA

Mixed ions and electron conductors(MIECs)are an important family of electrocatalysts for electrochemical devices,such as reversible solid oxide cells,rechargeable metal-air batteries,and oxygen transport *** ionic and electronic transports in these materials play a key role in electrocatalytic *** in-depth fundamental understanding of the transport phenomena is critically needed to develop better *** this brief review,we introduced generic ionic and electronic transport theory based on irreversible thermodynamics and applied it to practical oxide-based materials with oxygen vacancies and electrons/holes as the predominant *** oxide systems,namely CeO_(2)-based and La CrO_(3)-based materials,are selected as case studies to illustrate the utility of the transport theory in predicting oxygen partial pressure distribution across MIECs,electrochemical electronic/ionic leakage currents,and the effects of external load current on the leakage currents.

关键词： irreversible thermodynamics diffusivity charge neutrality electrochemical potential electrostatic potential

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

Cooperative interactions between nano-antennas in a high-Q cavity for unidirectional light sources

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Light(Science & Applications) 2019年第1期8卷 82-95页

作者： kevin G.Cognee Hugo M.Doeleman Philippe Lalanne A.f.Koenderink Center for Nanophotonics AMOLFScience Park 1041098 XG AmsterdamThe Netherlands LP2N Institut d’Optique Graduate SchoolCNRSUniversity of Bordeaux33400 TalenceFrance Van der Waals-Zeeman Institute University of AmsterdamScience Park 9041090 GL AmsterdamThe Netherlands

We analyse the resonant mode structure and local density of states in high-Q hybrid plasmonic-photonic resonators composed of dielectric microdisks hybridized with pairs of plasmon antennas that are systematically swept in position through the cavity *** the one hand,this system is a classical realization of the cooperative resonant dipole–dipole interaction through a cavity mode,as is evident through predicted and measured resonance linewidths and *** the same time,our work introduces the notion of‘phased array’antenna physics into plasmonic-photonic *** predict that one may construct large local density of states(LDOS)enhancements exceeding those given by a single antenna,which are‘chiral’in the sense of correlating with the unidirectional injection of fluorescence into the *** report an experiment probing the resonances of silicon nitride microdisks decorated with aluminium antenna *** directly confirm the predicted cooperative effects of the coupled dipole antennas as a function of the antenna spacing on the hybrid mode quality factors and resonance conditions.

关键词： antenna antennas cavity