RESUMEN
Within the modern aquaculture goals, the present study aimed to couple sustainable aquafeed formulation and culturing systems. Two experimental diets characterized by 3 and 20% of fish meal replacement with full-fat spirulina-enriched black soldier fly (Hermetia illucens) prepupae meal (HPM3 and HPM20, respectively) were tested on European seabass (Dicentrarchus labrax) juveniles during a 90-day feeding trial performed in aquaponic systems. The experimental diets ensured 100% survival and proper zootechnical performance. No behavioral alterations were evidenced in fish. Histological and molecular analyses did not reveal structural alterations and signs of inflammation at the intestinal level, highlighting the beneficial role on gut health of bioactive molecules typical of HPM or derived from the enriching procedure of insects' growth substrate with spirulina. Considering the quality traits, the tested experimental diets did not negatively alter the fillet's fatty acid profile and did not compromise the fillet's physical features. In addition, the results highlighted a possible role of spirulina-enriched HPM in preserving the fillet from lipid oxidation. Taken together, these results corroborate the use of sustainable ingredients (spirulina-enriched HPM) in aquaponic systems for euryhaline fish rearing.
RESUMEN
We report on the direct observation of backscattering induced by sidewall roughness in high-index-contrast optical waveguides based on total internal reflection. Our results demonstrate that backscattering is one of the most severe limiting factors in state-of-the art silicon on insulator nanowires employed in densely integrated photonics. We also derive the general relationship between backscattering and geometrical and optical parameters of the waveguide. Further, the role of roughness in polarization rotation and coupling with higher-order modes is pointed out.
RESUMEN
We report the first (to our knowledge) experimental observation of resonant cavity-enhanced photosensitivity in As(2)S(3) chalcogenide glass film at 1550 nm telecommunication wavelength. The measured photosensitivity threshold is <0.1 GW/cm(2), and a photoinduced refractive index increase as large as 0.016 is observed. The photosensitive process is athermal; further, we confirm the absence of two-photon absorption in As(2)S(3), suggesting that defect absorption accounts for the energy transfer from photons to glass network. Besides its potential application for reconfigurable photonics circuit, such photosensitivity is also an important design consideration for nonlinear optical devices using chalcogenide glasses.
RESUMEN
We present a technological approach to the realization of channeled optical waveguides, starting from reactively sputtered tellurite glass thin films, grown on silica-coated 4" Si wafers. In particular, optical lithographic process and etching recipes have been developed to overcome the solubility of TeO(2) films in aqueous solutions, and to process them into high-index contrast structures with minimized post-etch roughness. Optical tests on preliminary rib waveguide geometries feature 6.3 dB/cm propagation loss for fundamental TE mode at lambda = 1.5 microm.