261 research outputs found
Fano collective resonance as complex mode in a two-dimensional planar metasurface of plasmonic nanoparticles
Fano collective resonance as complex mode in a two dimensional planar metasurface of plasmonic nanoparticles
Fano resonances are features in transmissivity/reflectivity/absorption that
owe their origin to the interaction between a bright resonance and a dark
(i.e., sub-radiant) narrower resonance, and may emerge in the optical
properties of planar two-dimensional (2D) periodic arrays (metasurfaces) of
plasmonic nanoparticles. In this Letter, we provide a thorough assessment of
their nature for the general case of normal and oblique plane wave incidence,
highlighting when a Fano resonance is affected by the mutual coupling in an
array and its capability to support free modal solutions. We analyze the
representative case of a metasurface of plasmonic nanoshells at ultraviolet
frequencies and compute its absorption under TE- and TM-polarized, oblique
plane-wave incidence. In particular, we find that plasmonic metasurfaces
display two distinct types of resonances observable as absorption peaks: one is
related to the Mie, dipolar resonance of each nanoparticle; the other is due to
the forced excitation of free modes with small attenuation constant, usually
found at oblique incidence. The latter is thus an array-induced collective Fano
resonance. This realization opens up to manifold flexible designs at optical
frequencies mixing individual and collective resonances. We explain the
physical origin of such Fano resonances using the modal analysis, which allows
to calculate the free modes with complex wavenumber supported by the
metasurface. We define equivalent array dipolar polarizabilities that are
directly related to the absorption physics at oblique incidence and show a
direct dependence between array modal phase and attenuation constant and Fano
resonances. We thus provide a more complete picture of Fano resonances that may
lead to the design of filters, energy-harvesting devices, photodetectors, and
sensors at ultraviolet frequencies.Comment: 6 pages, 5 figure
Second harmonic double resonance cones in dispersive hyperbolic metamaterials
We study the formation of second harmonic double-resonance cones in
hyperbolic metamaterials. An electric dipole on the surface of the structure
induces second harmonic light to propagate into two distinct volume
plasmon-polariton channels: A signal that propagates within its own peculiar
resonance cone; and a phase-locked signal that is trapped under the pump's
resonance cone. Metamaterial dispersion and birefringence induce a large
angular divergence between the two volume plasmon-polaritons, making these
structures ideal for subwavelength second and higher harmonic imaging
microscopy
Gain assisted harmonic generation in near-zero permittivity metamaterials made of plasmonic nanoshells
Expanded Total Equivalent Warming Impact analysis on experimental standalone fresh-food refrigerator
The stand-alone refrigerators for fresh food storage represent a large part of supermarket refrigeration equip-ment. In these devices, the usage of refrigerants with low Global Warming Potential allows the mitigation of the direct emissions due to refrigerant leakages. In contrast, the indirect emissions in these components are highly dependent on the refrigerant charge, leakage, and equivalent emission factors related to the electricity pro-duction mix. The most used index to evaluate the environmental impact of refrigerators is the Total Equivalent Warming Impact. Despite that this index presents limits on the fixed evaluation of many parameters such as refrigerant charge, electricity consumption and, electricity emission factor. Otherwise in this study, an accurate evaluation of refrigerators emissions has been realised by using the innovative Expanded Total Equivalent Warming Impact method to an experimental stand-alone refrigerator by using a dynamic approach to evaluate direct and indirect contributions. The environmental analysis considers four different refrigerants and four different countries of location. The results show that the indirect emissions due to electricity consumption cover the highest share of emissions. In addition, the operating years affected by low refrigerant charges are respon-sible for emissions by greater than 25% compared to other ones. The hourly equivalent emissions due to elec-tricity consumption in countries characterized by an electricity generation mix mainly based on renewable and/ or nuclear plants show an indirect environmental impact up to 5 times lower than countries with a natural gas -based electricity production mix. The study also defines new strategies to reduce the environmental impact of the stand-alone refrigerator such as the use of photovoltaic systems combined with this technology or earlier maintenance processes that could determine an equivalent emission saving of up to 38%
MULTI-ROTOR WAKE INTERACTION CHARACTERIZATION
The paper presents part of the experimental activities carried out in the GARTEUR Action Group HC/AG-26 to
study the acoustic and aerodynamic characteristics of small rotor configurations, including the influence of the
rotor-rotor interactions. Two rotors equipped with two-bladed propellers with a diameter of D=165.1mm were
used at two different rotating speeds of 8025 RPM and 10120 RPM and different geometry configurations.
Isolated rotor and coaxial configurations in hover conditions were assessed. The rotor slipstream
characterization, in terms of aerodynamic loads, flow field velocity and acoustics emissions, was performed
using a six-component load cell, Particle Image Velocimetry and microphone array measurements. The effect
of the rotor support/fairing on the performance of the isolated rotor was investigated together with the rotorrotor interaction for the coaxial configuration at two rotor distances of Δz = 0.5R and Δz = 1.0 R. The results
indicated an effect of the support/fairing on the propeller performance, a loss of thrust of the lower rotor and a
higher noise emission for the coaxial configuration characterized by the larger rotor distance. The turbulent
kinetic energy and the meandering of the blade tip vortices sustained the acoustics results
Metallo-Dielectric Multilayer Structure for Lactose Malabsorption Diagnosis through H2 Breath Test
A metallo-dielectric multilayer structure is proposed as a novel approach to
the analysis of lactose malabsorption. When lactose intolerance occurs, the
bacterial overgrowth in the intestine causes an increased spontaneous emission
of H2 in the human breath. By monitoring the changes in the optical properties
of a multilayer palladium-polymeric structure, one is able to detect the
patient's disease and the level of lactose malabsorption with high sensitivity
and rapid response
Monitoring multiple myeloma by idiotype-specific peptide binders of tumor-derived exosomes.
Abstract Tumor-derived exosomes (TDEs) play a pivotal role in tumor establishment and progression, and are emerging biomarkers for tumor diagnosis in personalized medicine. To date, there is a lack of efficient technology platforms for exosome isolation and characterization. Multiple myeloma (MM) is an incurable B-cell malignancy due to the rapid development of drug-resistance. MM-released exosomes express the immunoglobulin B-cell receptor (Ig-BCR) of the tumor B-cells, which can be targeted by Idiotype-binding peptides (Id-peptides). In this study, we analyzed the production of MM-released exosomes in the murine 5T33MM multiple myeloma model as biomarkers of tumor growth. To this end, we selected Id-peptides by screening a phage display library using as bait the Ig-BCR expressed by 5T33MM cells. By FACS, the FITC-conjugated Id-peptides detected the MM-released exosomes in the serum of 5T33MM-engrafted mice, levels of which are correlated with tumor progression at an earlier time point compared to serum paraprotein. These results indicate that Id-peptide-based recognition of MM-released exosomes may represent a very sensitive diagnostic approach for clinical evaluation of disease progression
Evidence of shared epitopic reactivity among independent B-cell clones in chronic lymphocytic leukemia patients
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