Examinando por Materia "interferometry"

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    Contributions of intermolecular bonding and lubrication to the mechanical behavior of a natural armor
    (ELSEVIER SCI LTD, 2020-01-01) Jiang, H.; Ghods, S.; Weller, E.; Waddell, S.; Ossa, E.A.; Yang, F.; Arola, D.; Jiang, H.; Ghods, S.; Weller, E.; Waddell, S.; Ossa, E.A.; Yang, F.; Arola, D.; Universidad EAFIT. Departamento de Ingeniería de Producción; Materiales de Ingeniería
    Among many dermal armors, fish scales have become a source of inspiration in the pursuit of “next-generation” structural materials. Although fish scales function in a hydrated environment, the role of water and intermolecular hydrogen bonding to their unique structural behavior has not been elucidated. Water molecules reside within and adjacent to the interpeptide locations of the collagen fibrils of the elasmodine and provide lubrication to the protein molecules during deformation. We evaluated the contributions of this lubrication and the intermolecular bonding to the mechanical behavior of elasmodine scales from the Black Carp (Mylopharyngodon piceus). Scales were exposed to polar solvents, followed by axial loading to failure and the deformation mechanisms were characterized via optical mechanics. Displacement of intermolecular water molecules by liquid polar solvents caused significant (p = 0.05) increases in stiffness, strength and toughness of the scales. Removal of this lubrication decreased the capacity for non-linear deformation and toughness, which results from the increased resistance to fibril rotations and sliding caused by molecular friction. The intermolecular lubrication is a key component of the “protecto-flexibility” of scales and these natural armors as a system; it can serve as an important component of biomimetic-driven designs for flexible armor systems. Statement of Significance: The natural armor of fish has become a topic of substantial scientific interest. Hydration is important to these materials as water molecules reside within the interpeptide locations of the collagen fibrils of the elasmodine and provide lubrication to the protein molecules during deformation. We explored the opportunity for tuning the mechanical behavior of scales as a model for next-generation engineering materials by adjusting the extent of hydrogen bonding with polar solvents and the corresponding interpeptide molecular lubrication. Removal of this lubrication decreased the capacity for non-linear deformation and toughness due to an increase in resistance to fibril rotations and sliding as imparted by molecular friction. We show that intermolecular lubrication is a key component of the “protecto-flexibility” of natural armors and it is an essential element of biomimetic approaches to develop flexible armor systems. © 2020 Acta Materialia Inc.
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    Lab-made accessible full-field optical coherence tomography imaging system
    (Sociedad Espanola de Optica, 2019-09-01) Cuartas-Velez, Carlos; Ruiz-Lopera, Sebastian; Uribe-Patarroyo, Nestor; Restrepo, Rene; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    In this work, an easy to understand optical system was developed for the study of the medical imaging technique optical coherence tomography (OCT). This technique allows volumetric reconstruction of inhomogeneous, non-transparent and scattering samples such as biological tissues. The implementation was based on using non-specialized components for OCT under the scheme of a Michelson interferometer with a CCD camera to capture the interference patterns in a configuration known as full field OCT (FFOCT). Our system, explained in detail, was designed using components commonly found in most optical labs because our focus is to provide an accessible experimental setup for understanding the basics of OCT. The developed system possesses an axial resolution of 1.74 mu m and a lateral resolution of 4.5 mu m. With the described system, tomograms of two samples were obtained: a metal coin and an ex-vivo insect wing of the blattodea family.