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排序方式: 共有492条查询结果,搜索用时 15 毫秒
81.
Alessio Crescitelli Armando Ricciardi Marco Consales Emanuela Esposito Carmine Granata Vincenzo Galdi Antonello Cutolo Andrea Cusano 《Advanced functional materials》2012,22(20):4389-4398
The first evidence of out‐of‐plane resonances in hybrid metallo‐dielectric quasi‐crystal (QC) nanostructures composed of metal‐backed aperiodically patterned low‐contrast dielectric layers is reported. Via experimental measurements and full‐wave numerical simulations, these resonant phenomena are characterized with specific reference to the Ammann‐Beenker (quasi‐ periodic, octagonal) tiling lattice geometry and the underlying physics is investigated. In particular, it is shown that, by comparison with standard periodic structures, a moderately richer spectrum of resonant modes may be excited, due to the easier achievement of phase‐matching conditions endowed by its denser Bragg spectrum. Such modes are characterized by a distinctive plasmonic or photonic behavior, discriminated by their field distribution and dependence on the metal film thickness. Moreover, the response is accurately predicted via computationally affordable periodic‐approximant‐based numerical modeling. The enhanced capability of QCs to control number, spectral position, and mode distribution of hybrid resonances may be exploited in a variety of possible applications. To assess this aspect, label‐free biosensing is studied via characterization of the surface sensitivity of the proposed structures with respect to local refractive index changes. Moreover, it is also shown that the resonance‐engineering capabilities of QC nanostructures may be effectively exploited in order to enhance the absorption efficiency of thin‐film solar cells. 相似文献
82.
Prof. Silvia Rivara Dr. Daniele Pala Dr. Alessio Lodola Prof. Marco Mor Dr. Valeria Lucini Dr. Silvana Dugnani Prof. Francesco Scaglione Dr. Annalida Bedini Dr. Simone Lucarini Prof. Giorgio Tarzia Prof. Gilberto Spadoni 《ChemMedChem》2012,7(11):1954-1964
The design of compounds selective for the MT1 melatonin receptor is still a challenging task owing to the limited knowledge of the structural features conferring selectivity for the MT1 subtype, and only few selective compounds have been reported so far. N‐(Anilinoalkyl)amides are a versatile class of melatonin receptor ligands that include nonselective MT1/MT2 agonists and MT2‐selective antagonists. We synthesized a new series of N‐(anilinoalkyl)amides bearing 3‐arylalkyloxy or 3‐alkyloxy substituents at the aniline ring, looking for new potent and MT1‐selective ligands. To evaluate the effect of substituent size and shape on binding affinity and intrinsic activity, both flexible and conformationally constrained derivatives were prepared. The phenylbutyloxy substituent gave the best result, providing the partial agonist 4 a , which was endowed with high MT1 binding affinity (pKi=8.93) and 78‐fold selectivity for the MT1 receptor. To investigate the molecular basis for agonist recognition, and to explain the role of the 3‐arylalkyloxy substituent, we built a homology model of the MT1 receptor based on the β2 adrenergic receptor crystal structure in its activated state. A binding mode for MT1 agonists is proposed, as well as a hypothesis regarding the receptor structural features responsible for MT1 selectivity of compounds with lipophilic arylalkyloxy substituents. 相似文献
83.
Alessio Torrielli Federica Tubino Giovanni Solari 《Journal of Wind Engineering & Industrial Aerodynamics》2010,98(8-9):417-428
Gust buffeting of structures is analyzed by Double Modal Transformation, a method consisting in the joint transformation into principal components of structural displacements (modal analysis) and of wind loading (proper orthogonal decomposition). It commonly occurs that modal truncation applies to both the series of structural and loading modes; besides, many loading modes are almost orthogonal respect the dominant structural modes, so they do not contribute to structural response. This set of conditions allows the introduction of an effective action, defined as the loading process reconstructed retaining only those loading modes that excite the structure. This paper discusses this method and the related concepts by analyzing a set of simple ideal structures in closed form; this approach allows the formulation of general criteria aimed at defining the effective wind action as a function of non-dimensional structural and wind parameters. The numerical analysis of a real structure confirms the tendencies pointed out by the analytical solutions. 相似文献
84.
Antonella Gori Cecilia Brunetti Luana Beatriz dos Santos Nascimento Giovanni Marino Lucia Guidi Francesco Ferrini Mauro Centritto Alessio Fini Massimiliano Tattini 《International journal of molecular sciences》2021,22(15)
Carotenoids and phenylpropanoids play a dual role of limiting and countering photooxidative stress. We hypothesize that their “antioxidant” function is prominent in plants exposed to summer drought, when climatic conditions exacerbate the light stress. To test this, we conducted a field study on Phillyrea latifolia, a Mediterranean evergreen shrub, carrying out daily physiological and biochemical analyses in spring and summer. We also investigated the functional role of the major phenylpropanoids in different leaf tissues. Summer leaves underwent the most severe drought stress concomitantly with a reduction in radiation use efficiency upon being exposed to intense photooxidative stress, particularly during the central hours of the day. In parallel, a significant daily variation in both carotenoids and phenylpropanoids was observed. Our data suggest that the morning-to-midday increase in zeaxanthin derived from the hydroxylation of ß-carotene to sustain non-photochemical quenching and limit lipid peroxidation in thylakoid membranes. We observed substantial spring-to-summer and morning-to-midday increases in quercetin and luteolin derivatives, mostly in the leaf mesophyll. These findings highlight their importance as antioxidants, countering the drought-induced photooxidative stress. We concluded that seasonal and daily changes in photosynthetic and non-photosynthetic pigments may allow P. latifolia leaves to avoid irreversible photodamage and to cope successfully with the Mediterranean harsh climate. 相似文献
85.
Alessio Frassoldati Pratyush Sharma Alberto Cuoci Tiziano Faravelli Eliseo Ranzi 《Applied Thermal Engineering》2010,30(4):376-383
MILD combustion is a recent development in the combustion of hydrocarbon fuels which promises high efficiencies and low NOx emissions. In this paper we analyze the mathematical and numerical modeling of a Jet in Hot Coflow (JHC) burner, which is designed to emulate a moderate and intense low oxygen dilution (MILD) combustion regime [1]. This paper initially discusses the effects of several modeling strategies on the prediction of the JHC flame structure using the CFD code FLUENT 6.3.26. Effects of various turbulence models and their boundary conditions have been studied. Moreover, the detailed kinetic mechanism adopted in the CFD simulations is successfully validated in the conditions of interest using recent literature data [2] on the effect of nitrogen dilution on the flame speeds of several CH4/H2/air lean mixtures. One of the aims of this paper is also to describe a methodology for computing pollutant formation in steady turbulent flows to verify its applicability to the MILD combustion regime. CFD results are post-processed for calculating the NOx using a numerical tool called Kinetic Post Processor (KPP). The modeling results agree with the experimental results [1] and support the proposed approach as a useful tool for optimizing the design of new burners also in the MILD combustion regime. 相似文献
86.
The erosion process at a bridge abutment may be affected by the flow constriction when the abutment occupies a significant part of the flume width. We devised a specific experimental campaign to investigate the effect of the obstruction ratio (i.e., the ratio between the abutment length and the channel width) on the erosion depth: we performed homogeneous series of clear-water scour experiments in each of which the obstruction ratio was the only parameter that varied. The experimental results are presented in light of a dimensionless framework. It was found that the effect of the obstruction ratio on the time development of local scour depth may not be large; nevertheless, significant effect can be observed, even for relatively small values of the parameter during the earliest phases. The latter are important, for example, for the step-by-step modeling of the erosion development under unsteady flow conditions. We propose a simple equation to quantify the scour enhancement due to the flow constriction in clear-water abutment scour. 相似文献
87.
Effect of short carbon fibers and MWCNTs on microwave absorbing properties of polyester composites containing nickel-coated carbon fibers 总被引:1,自引:0,他引:1
Igor Maria De Rosa Adrian Dinescu Fabrizio Sarasini Maria Sabrina Sarto Alessio Tamburrano 《Composites Science and Technology》2010
Multiphase composite materials filled with multiwall carbon nanotubes (MWCNTs), short nickel-coated carbon fibers and millimeter-long carbon fibers with various weight fractions and compositions are developed and used for the design of wide-band thin radar-absorbing screens. The effective complex permittivity of several composite samples is measured in the frequency range from 8 GHz to 18 GHz. The obtained results show that the addition of the MWCNTs into the mixture allows tuning the EM properties of the composite filled with the short nickel-coated fibers. Numerical simulations are also performed in order to design new radar-absorbing shields. Single-layer and bi-layer thin dielectric Salisbury screens are designed to exhibit minimum reflection coefficient at 10 GHz and at 15 GHz, and maximum bandwidth at −10 dB. It results that the total thickness of the screen can be reduced below 2 mm by using a lossy sheet made with the composite filled with MWCNTs and nickel-coated carbon fibers, whereas the bandwidth at −10 dB can exceed 6 GHz in a bi-layer structure. 相似文献
88.
Electrically conductive fabrics were produced by deposition of a thin film of doped polypyrrole on the surface of cotton fibres. In situ oxidative chemical polymerisation were carried out in aqueous solutions of pyrrole, oxidant and doping agents, at room temperature. Polypyrrole-coated fibres were characterized by Light Microscopy, SEM, EDX, FTIR and TGA. Moreover, fabric samples were also evaluated for moisture regain, electrical resistivity, heat generation and antibacterial activity. PPy alters the combustion process of cellulose fibres that maintain the fibrous shape after heating in air. Moreover, it seems that PPy is really an antibacterial agent, apart from the oxidant or dopant used. The results highlight potential applications as technical textiles with antistatic (low electrical resistance), heat generation, hygroscopy, antibacterial and high temperature resistance properties. 相似文献
89.
Stefano Farris Carlo Alessio Cozzolino Laura Introzzi Luciano Piergiovanni 《Packaging Technology and Science》2009,22(6):359-369
This paper presents the results of an investigation through the design of experiment technique regarding the influence of temperature, dwell time and bar pressure on the heat seal strength of oriented polypropylene films coated with a gelatin‐based thin layer. This chemometric approach allowed achieving a thorough understanding of the effect of each independent factor on the two different responses (maximum force and strain energy) considered in this work as a measure of the strength necessary to break the bond across the sealed interface. Surprisingly, the factor affecting both responses the most was the bar pressure rather than the sealing temperature. Moreover, whereas the bar pressure negatively affected the seal strength of coated polypropylene films, the sealing temperature had a positive effect. Dwell time did not have any significant influence as a main factor, while influencing negatively the seal strength as an interaction term (i.e. time × pressure), together with the further interaction temperature × pressure. The mathematical models obtained for the two responses provided different results in terms of fitting capability (R2) and prediction ability (Q2). In particular, for the maximum force response, R2 and Q2 were equal to 0.571 and 0.405, respectively, whereas the model supporting the strain energy response gave R2 = 0.932 and Q2 = 0.937, highlighting that for quantifying the seal strength, the energy necessary to break a seal is a better measure than the maximum force. The highest seal strength values obtained during this work were of 0.6615 N and 19.6 N·mm for maximum force and strain energy, respectively. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
90.