Search results for "surface"
showing 10 items of 9345 documents
Perfluoroalkylated amphiphilic MUC1 glycopeptide antigens as tools for cancer immunotherapy.
2010
The synthesis of perfluoroalkylated glycopeptide antigens and their specific binding to anti-MUC1 mouse antibodies is reported.
What we learn about bipolar disorder from large-scale neuroimaging
2020
Abstract MRI‐derived brain measures offer a link between genes, the environment and behavior and have been widely studied in bipolar disorder (BD). However, many neuroimaging studies of BD have been underpowered, leading to varied results and uncertainty regarding effects. The Enhancing Neuro Imaging Genetics through Meta‐Analysis (ENIGMA) Bipolar Disorder Working Group was formed in 2012 to empower discoveries, generate consensus findings and inform future hypothesis‐driven studies of BD. Through this effort, over 150 researchers from 20 countries and 55 institutions pool data and resources to produce the largest neuroimaging studies of BD ever conducted. The ENIGMA Bipolar Disorder Workin…
Decomposition Process of Carboxylate MOF HKUST-1 Unveiled at the Atomic Scale Level
2016
HKUST-1 is a metal-organic framework (MOF) which plays a significant role both in applicative and basic fields of research, thanks to its outstanding properties of adsorption and catalysis but also because it is a reference material for the study of many general properties of MOFs. Its metallic group comprises a pair of Cu2+ ions chelated by four carboxylate bridges, forming a structure known as paddle-wheel unit, which is the heart of the material. However, previous studies have well established that the paddle-wheel is incline to hydrolysis. In fact, the prolonged exposure of the material to moisture promotes the hydrolysis of Cu-O bonds in the paddle-wheels, so breaking the crystalline n…
Second order nonlinear optics in AlGaAs metasurfaces
2023
Recently, nonlinear optics at the nanoscale level has emerged as a promising branch of nanophotonics. In this work, we focus our attention on Aluminum Gallium Arsenide (AlGaAs) nanoantennas and metasurfaces for efficient and controlled second harmonic photon emission. After a brief introduction concerning the main studies in this field, we present the latest results achieved in AlGaAs platforms both in the lossless and absorption regimes.
Silicon metasurfaces with tunable electromagnetic resonances for nonlinear optical conversion
2021
Dielectric metasurfaces sustain electromagnetic modes which can be exploited to enhance nonlinear frequency-conversion processes such as third-harmonic generation. In this work we employ electron-beam lithography to fabricate silicon metasurfaces supporting electromagnetic resonances with different quality factors (Q), ruled by the geometry. This allows to investigate the trade-off between resonant enhancement and matching the spectral bandwidth of the ultrafast excitation source. Both experiments and simulations indicate that higher values of Q do not a priori bring about a stronger third-harmonic generation, which correlates to the spectral overlap between the metasurface resonance and th…
Fundamental limits for transmission modulation in VO2 metasurfaces
2022
The interest in dynamic modulation of light by ultra-thin materials exhibiting insulator–metal phase transition, such as VO 2 , has rapidly grown due to the myriad industrial applications, including smart windows and optical limiters. However, for applications in the telecommunication spectral band, the light modulation through a thin VO 2 film is low due to the presence of strong material loss. Here, we demonstrate tailored nanostructuring of VO 2 to dramatically enhance its transmission modulation, reaching a value as high as 0.73, which is 2 times larger than the previous modulation achieved. The resulting designs, including free-topology optimization, demonstrate the fundamental limit i…
Manipulating Light with Tunable Nanoantennas and Metasurfaces
2022
The extensive progress in nanofabrication techniques enabled innovative methods for molding light at the nanoscale. Subwavelength structured optical elements and, in general, metasurfaces and metamaterials achieved promising results in several research areas, such as holography, microscopy, sensing and nonlinear optics. Still, a demanding challenge is represented by the development of innovative devices with reconfigurable optical properties. Here, we review recent achievements in the field of tunable metasurface. After a brief general introduction about metasurfaces, we will discuss two different mechanisms to implement tunable properties of optical elements at the nanoscale. In particular…
Uniformization of two-dimensional metric surfaces
2014
We establish uniformization results for metric spaces that are homeomorphic to the Euclidean plane or sphere and have locally finite Hausdorff 2-measure. Applying the geometric definition of quasiconformality, we give a necessary and sufficient condition for such spaces to be QC equivalent to the Euclidean plane, disk, or sphere. Moreover, we show that if such a QC parametrization exists, then the dilatation can be bounded by 2. As an application, we show that the Euclidean upper bound for measures of balls is a sufficient condition for the existence of a 2-QC parametrization. This result gives a new approach to the Bonk-Kleiner theorem on parametrizations of Ahlfors 2-regular spheres by qu…
Nodular cast iron fatigue lifetime in cyclic plane bending
2012
The fatigue behavior of a component is strongly dependent on the material and its surface condition. Therefore, the manner in which the surface is prepared during component manufacturing (surface roughness, residual stresses etc.) has a decisive role in dictating the initiation time for fatigue cracks. The fatigue behavior of the same material, a nodular cast iron, with three different surface conditions (fine ground, sand blast and as-cast) has been investigated under cyclic plane bending. The results show differences in fatigue strength, which are associated with the surface conditions. The characteristics of the surface layers of the different test specimens were examined by metallograph…
Microwave response of bulk MgB2 samples of different granularity
2006
The microwave response of three high-density bulk MgB2 samples has been investigated in the linear and nonlinear regimes. The three samples, characterized by different mean size of grains, have been obtained by reactive infiltration of liquid Mg in powdered B preforms. The linear response has been studied by measuring the microwave surface impedance; the nonlinear response by detecting the power radiated by the sample at the second-harmonic frequency of the driving field. Our results suggest that bulk MgB2 prepared by the liquid Mg infiltration technique is particularly promising for manufacturing resonant cavities operating at microwave frequencies.