1,720,973 research outputs found
Large-Area Plasmonics on Self-Organized Wrinkled Nanopatterns
No full textThe focus of my PhD project consisted in the development of self-organized, large area, industrially scalable physical methods based on wrinkling instabilities to nanopattern and functionalize tunable plasmonic polymeric polydimetilsyloxane (PDMS) and solid-state glass surfaces, both transparent, non-toxic and cheap materials, for applications of significant technological interest in photonics and bio-sensing
Free-standing plasmonic nanoarrays for leaky optical waveguiding and sensing
Full text linkFlat optics nanogratings supported on thin free-standing membranes offer the opportunity to combine narrowband waveguided modes and Rayleigh anomalies for sensitive and tunable biosensing. At the surface of high-refractive index Si3N4 membranes we engineered lithographic nanogratings based on plasmonic nanostripes, demonstrating the excitation of sharp waveguided modes and lattice resonances. We achieved fine tuning of these optical modes over a broadband Visible and Near-Infrared spectrum, in full agreement with numerical calculations. This possibility allowed us to select sharp waveguided modes supporting strong near-field amplification, extending for hundreds of nanometres out of the grating and enabling versatile biosensing applications. We demonstrate the potential of this flat-optics platform by devising a proof-of-concept nanofluidic refractive index sensor exploiting the long-range waveguided mode operating at the sub-picoliter scale. This free-standing device configuration, that could be further engineered at the nanoscale, highlights the strong potential of flat-optics nanoarrays in optofluidics and nanofluidic biosensing. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreemen
Large-area flexible nanostripe electrodes featuring plasmon hybridization engineering
No full textMultifunctional flexible Au electrodes based on one-dimensional (1D) arrays of plasmonic gratings are nanofabricated over large areas with an engineered variant of laser interference lithography optimized for low-cost transparent templates. Au nanostripe (NS) arrays achieve sheet resistance in the order of 20 Ohm/square on large areas (∼ cm2) and are characterized by a strong and dichroic plasmonic response which can be easily tuned across the visible (VIS) to near-infrared (NIR) spectral range by tailoring their cross-sectional morphology. Stacking vertically a second nanostripe, separated by a nanometer scale dielectric gap, we form near-field coupled Au/SiO2/Au dimers which feature hybridization of their localized plasmon resonances, strong local field-enhancements and a redshift of the resonance towards the NIR range. The possibility to combine excellent transport properties and optical transparency on the same plasmonic metasurface template is appealing in applications where low-energy photon management is mandatory like e.g., in plasmon enhanced spectroscopies or in photon harvesting for ultrathin photovoltaic devices. The remarkable lateral order of the plasmonic NS gratings provides an additional degree of freedom for tailoring the optical response of the multifunctional electrodes via the excitation of surface lattice resonances, a Fano-like coupling between the broad localised plasmonic resonances and the collective sharp Rayleigh modes
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Infrared Plasmonics via Self-Organized Anisotropic Wrinkling of Au/PDMS Nanoarrays
No full textPolydimethylsiloxane
(PDMS) templates are nanopatterned over large
areas to form uniaxial wrinkles by air plasma treatment on prestretched
samples. Ripple-like structures with tunable height/width aspect ratio
are so achieved. The anisotropic uniaxial PDMS modulations represent
an ideal platform for the confinement of plasmonic nanowire (NW) arrays
by grazing angle Au thermal deposition. This self-organized fabrication
method is suitable to be scaled to the industrial level as a single
step maskless process. The flexible NW arrays show monodisperse width
distribution and exhibit strongly dichroic optical properties. Localized
surface plasmon resonances (LSPR) of dipolar and multipolar character
are excited when light is linearly polarized orthogonally to the NW
major axis. The LSPR wavelength can be easily tuned across a remarkably
large spectral range from 600 to 1200 nm by engineering the NW width
and the PDMS ripple morphology. The PDMS/Au NW nanocomposite material
also shows relevant performance as a transparent flexible electrode
with sheet resistance on the order of 15 Ω/sq, a figure of merit
which is competitive with the best transparent conductive oxides
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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