Heavy landing of Charybdis smithii and need for proper utilization

Heavy landings of Charybdis smithii during the January to March, 2020 was documented in Mangalore fisheries harbour. These crabs were the part of trawl discards as geo-coded in situ data collection on trawl discards showed that C. smithii was available along Karnataka coast during August to December and in May as pelagic or semi-pelagic shoals from a depth range of more than 100 m. Landing of this species in Fisheries Harbours was generally rare since there was very limited market demand for these crab

Magnetic metamaterials in the blue range using aluminum nanostructures

We report an experimental and theoretical study of the optical properties of two-dimensional arrays of aluminum nanoparticle in-tandem pairs. Plasmon resonances and effective optical constants of these structures are investigated and strong magnetic response as well as negative permeability are observed down to 400 nm wavelength. Theoretical calculations based on the finite-difference time-domain method are performed for various particle dimensions and lattice parameters, and are found to be in good agreement with the experimental results. The results show that metamaterials operating across the whole visible wavelength range are feasible.Comment: 3 pages, 4 figure

Epitope-Based Immunoinformatics and Molecular Docking Studies of Nucleocapsid Protein and Ovarian Tumor Domain of Crimean–Congo Hemorrhagic Fever Virus

Crimean–Congo hemorrhagic fever virus (CCHFV), the fatal human pathogen is transmitted to humans by tick bite, or exposure to infected blood or tissues of infected livestock. The CCHFV genome consists of three RNA segments namely, S, M, and L. The unusual large viral L protein has an ovarian tumor (OTU) protease domain located in the N terminus. It is likely that the protein may be autoproteolytically cleaved to generate the active virus L polymerase with additional functions. Identification of the epitope regions of the virus is important for the diagnosis, phylogeny studies, and drug discovery. Early diagnosis and treatment of CCHF infection is critical to the survival of patients and the control of the disease. In this study, we undertook different in silico approaches using molecular docking and immunoinformatics tools to predict epitopes which can be helpful for vaccine designing. Small molecule ligands against OTU domain and protein–protein interaction between a viral and a host protein have been studied using docking tools

Linear and nonlinear plasmonic effects in asymmetric nanostructures

The invention of modern nanofabrication tools like electron beam lithography has enabled us to create increasingly complex nanostructures to study the confinement of different entities such as electrons, photons, fluxons, etc. Our group at the KU Leuven has a long tradition on the study of confinement and manipulation of fluxons in superconductors using nano and micro structures. Particular attention has been paid to asymmetric and periodic systems which permit one to rectify and guide fluxons. In this thesis we explore how the lessons learned in nanostructured superconductivity in controlling the motion of fluxons can be mapped or extended to other physical systems beyond the superconductivity domain. Surface plasmons are collective charge oscillations at the interface between a metallic structure and a dielectric medium. When light impinges onto a metallic surface, charge oscillations induced by the electric field of the light screens it from entering. This collective excitation combining an electromagnetic wave with oscillating charges can be, to some extent, controlled by nanostructuring the metallic surface. In a nanoparticle this collective excitation of the conduction electron is localized for it is confined in a finite volume of the metallic nanostructure and is accompanied by resonantly enhanced polarizabilities. At these resonance frequencies the nanoparticle strongly scatters and absorbs light. Excitation of localized plasmon resonance is also accompanied by nanoscale localization and enhancement of electromagnetic (EM) field. This localization generates strong current hotspots in the nanoparticle and through ohmic losses rapidly convert EM field in to thermal energy. By carefully designing the metal nanoparticle one could exploit these collective oscillation and their properties in building sensors, antennas, metamaterials, optical nanochips, solar cells and for medical applications to name a few.One of the growing fields in plasmonics is the study of its application in the field of biology. The localized plasmon resonances interaction with biomolecules and other cells have led to building novel sensors to understand molecular level biological processes, sensitive labels for immunoassays, nano-bioreactors and even in the development in treatment of cancer through photothermal therapy. There have also been recent studies that reported enhanced growth of photosynthetic microorganisms like cyanobacteria and microalgae assisted by enhanced back scattering due to localized surface plasmon resonances. We wanted to further investigate in this interdisciplinary field combining plasmonics and biology. We have started the study in this thesis first by understanding the physics behind the motion of self-motile microorganism E. coli. E. coli is a prokaryotic model organism and one of the most studied in the field of biology for its role as a model organism to create recombinant DNA. Normally these microorganisms act independently with some set of rules defined by the biology of the organisms and the laws of hydrodynamics. It is very helpful though to make them act collectively to better control their motion in a microfluidic environment which acts as a stepping stone in building optofluidic devices and bring together the field of plasmonics and the study of motile organisms. In this thesis we will also explore asymmetric micro structures in microfluidic environment which act like ratchets and can nudge the microorganism one way or another. We have also extended our study to human spermatozoa, which biologically functions a completely different role from E. coli but the physics behind their motions are very similar. This also opens a whole new door in understanding some aspects of human biology and shows the universality of our approach. In this thesis we will explore the above mentioned phenomena. By using geometrical asymmetry we exploit collective motion of plasmons for building refractive index sensors and by exploiting the accompanying thermal energy to image the current flow in the nanoparticle. We also try to bridge the study of plasmonics and self-motile microorganism first by trying to understand the physics behind their motion then by trying to control their motion in a microfluidic environment through geometrical asymmetry.status: publishe

Disposable Plasmonics: Rapid and Inexpensive Large Area Patterning of Plasmonic Structures with CO₂ Laser Annealing

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.langmuir.9b02253We present a method of direct patterning of plasmonic nanofeatures on glass that is fast, scalable, tunable, and accessible to a wide range of users-a unique combination in the context of current nanofabrication options for plasmonic devices. These benefits are made possible by the localized heating and subsequent annealing of thin metal films using infrared light from a commercial CO2 laser system. This approach results in patterning times of 30 mm(2)/min with an average cost of $0.10/mm(2). Colloidal Au nanoparticles with diameters between 15 and 40 nm can be formed on glass surfaces with x-y patterning resolutions of ∼180 μm. While the higher resolution provided by lithography is essential in many applications, in cases where the spatial patterning resolution threshold is lower, commercial CO2 laser processing can be 30-fold faster and 400-fold less expensive.This work was supported through a Strategic Grant from the Natural Science and Engineering Research Council of Canada (NSERC), the University of Toronto Connaught Global Challenges Program in Bio-Inspired Ideas for Sustainable Energy, the University of Toronto McLean Senior Fellowship (DS), the Vanier Canada Graduate Scholarship (MO), and on-going support from the NSERC Discovery Grant Program. Infrastructure support was provided from the Canada Foundation for Innovation

Disposable Plasmonics: Rapid and Inexpensive Large Area Patterning of Plasmonic Structures with CO₂ Laser Annealing

We present a method of direct patterning of plasmonic nanofeatures on glass that is fast, scalable, tunable, and accessible to a wide range of usersa unique combination in the context of current nanofabrication options for plasmonic devices. These benefits are made possible by the localized heating and subsequent annealing of thin metal films using infrared light from a commercial CO₂ laser system. This approach results in patterning times of 30 mm²/min with an average cost of $0.10/mm². Colloidal Au nanoparticles with diameters between 15 and 40 nm can be formed on glass surfaces with <i>x</i>–<i>y</i> patterning resolutions of ∼180 μm. While the higher resolution provided by lithography is essential in many applications, in cases where the spatial patterning resolution threshold is lower, commercial CO₂ laser processing can be 30-fold faster and 400-fold less expensive

Light-matter interactions mediated by nanoscale confinement in plasmonic resonators

Plasmonic resonators are nanosized metallic antennas that convert electromagnetic waves at optical frequencies into localized fields, providing an effective route to couple photons in and out of nanoscale volumes. This unique ability makes these nanostructures excellent tools to study and manipulate light-matter interaction at the nanoscale. The strong coupling of a plasmonic resonator to light, resulting in optical cross-sections of more than 10 times the particle’s physical size, is driven by collective oscillations of the conduction electrons in the metal – the so-called surface plasmon resonances. In the first part of this presentation, we will discuss how plasmonic resonances influence the second harmonic generation (SHG) from different resonator geometries. Linear optical properties examined by reflection spectroscopy, aperture scanning near-field optical microscopy (aperture-SNOM), and finite difference time domain (FDTD) simulations reveal the supported plasmonic modes and their field and current distributions [1,2]. These results are then compared with SHG microscopy measurements [3-5]. Luminescent Ag nanoclusters have been extensively studied recently for a variety of applications, such as bio-nanolabels, UV-driven white light generation for luminescent lamps, flexible screen monitors, and down-conversion of solar spectrum for enhanced solar cells. Bulk oxyfluoride glasses can embed such small Ag nanoclusters [6]. However, an extra heat treatment below the glass transition temperature of these glasses results in condensation of the Ag nanoclusters into Ag nanoparticles larger than 1 nm. In the second part of the talk, we will discuss how the surface plasmon modes in these nanoparticles mediate the luminescence of the Ag doped oxyfluoride glass [7].status: publishe

Light-matter interactions mediated by nanoscale confinement in plasmonic resonators

Plasmonic resonators are nanosized metallic antennas that convert electromagnetic waves at optical frequencies into localized fields, providing an effective route to couple photons in and out of nanoscale volumes. This unique ability makes these nanostructures excellent tools to study and manipulate light-matter interaction at the nanoscale. The strong coupling of a plasmonic resonator to light, resulting in optical cross-sections of more than 10 times the particle-s physical size, is driven by collective oscillations of the conduction electrons in the metal - the so-called surface plasmon resonances.2 page(s

Volumetric method of moments and conceptual multilevel building blocks for nanotopologies

Based on the relationship between charge dimensionality and singular field behavior, it is proven that in a volumetric description of a volume current carrying topology, half rooftops of different binary hierarchical level are allowed without introducing numerical difficulties. This opens the possibility to use a very efficient multi-level hierarchical meshing scheme in a Volumetric Method of Moments (MoM) algorithm. The new meshing scheme is validated by numerical calculations and experiments. It paves the way towards a much more efficient use of MoM in the description of arbitrarily shaped nano-structures at IR and optical frequencies