Ferroelectric nanoparticles, due to their high non-linear optical response, are of considerable practical interest for their use as nanoprobes for the study of biological materials by multiphoton microscopy methods. To prevent toxic effects, it is necessary to modify the surface using biocompatible polymers. Here we report the results of the study on the effect of surface modification of BaTiO3 nanoparticles with hydrolyzed chitosan obtained from shrimp exoskeletons (Penaeus vannamei). It was found that increasing of the hydrolyzed chitosan concentration in the solution during surface modification from 1 to 3% leads to a significant reduction in nanoparticle agglomeration, while the intensity of the second harmonic generation changes insignificantly.
Graphical abstract
In this work we studied the microfibers of a textile (T-shirt) of the Chimú culture. This culture developed on the northern coast of Peru. To determine the raw material and structural quality of the microfibers, the results of the Chimú textile were compared with the corresponding results for the microfibers of cotton from the northern coast of Peru (native cotton). Scanning electron microscopy images revealed that the Chimú textile yarns are composed of a set of interwoven microfibers. Energy dispersive X-ray spectroscopy and pulsed laser-induced plasma spectroscopy techniques allowed the identification of characteristic cellulose atoms in the microfibers of Chimú textile and native cotton. Only for the Chimú textile, these spectroscopic techniques allowed the identification of atoms corresponding to natural dyes and powder residues. Attenuated total reflection Fourier transform infrared spectroscopy identified the same molecular bonds for the microfibers of Chimú textile and native cotton. For the microfibers of Chimú textile and native cotton, the X-ray diffractograms showed peaks characteristic of the cellulose Iβ polymorphism of of monoclinic P21 structure. The raw material of the Chimú textile is cotton and the microfibers of this material show significant structural stability.
RESUMEN El presente trabajo reporta el efecto de la concentración (0,60-0,98 µM) de ácido ascórbico sobre la razón de aspecto (RA) de nanorods de oro con bandas de plasmón longitudinal (PL) en el infrarrojo cercano (958 – 1085 nm), crecidos por ruta química mediado por semillas. Como agente precursor se usó ácido cloroáurico tri-hidratado (HAuCl4.3H2O) obtenido a partir de oro metálico de alta pureza (99.99%) disuelto agua regia. Como agentes surfactantes fueron utilizados cloruro de bencildimetilhexadecilamonio (BDAC) y bromuro de cetiltrimetilamonio (CTAB) a una razón molar de 0,75 (BDAC/CTAB). Imágenes por microscopia electrónica de barrido implementado con un detector de electrones transmitidos y los espectros de absorción, revelaron que la RA se alcanza un máximo de 7,3 y una banda de PL de 1085 nm para una concentración crítica de ácido ascórbico de 0,75 µM, equivalente a una razón molar de AA/Au3+ de 1,5. Mayor incremento de ácido ascórbico hasta 0,98 µM, la RA disminuye hasta 6 y consecuentemente, su banda de PL disminuye hasta 958 nm.
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