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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

We studied the effect of the repetition rate of laser pulses (RRLP) in the range from 1–10 Hz in the production of silver nanoparticles (Ag-NPs) by laser ablation in ethanol. Laser pulses with a duration of 7 ns, a wavelength of 1064 nm and an energy of 60 mJ were used to ablate a 99.99% pure silver target immersed in 10 ml of ethanol. Transmittance analysis and atomic absorption spectroscopy were used to study the silver concentration in the colloidal solutions. The ablation process was studied by measuring the transmission of the laser pulses through the colloid. It is shown that for a fixed number of laser pulses (NLP) the ablation efficiency, in terms of the ablated silver mass per laser pulse, increases with the RRLP. This result contradicts what had previously been established in the literature.

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.

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The effect of magnetic field of 0.3 T on the concentration, distribution of sizes in suspension and zeta potential of colloidal gold and colloidal silver nanoparticles, obtained by considering the pulsed laser ablation in double distilled water was studied. The magnetic field was transverse to the direction of incidence of the laser radiation and parallel to the surface of a submerged target. An Nd: YAG laser was used (1064 nm in wavelength, 10 ns in duration, repetition rate of 10 Hz and 37 mJ of energy) to ablate targets. The colloids were characterized by inductively coupled plasma optical emission spectroscopy, ultraviolet-visible spectroscopy, dynamic light scattering and zeta potential. Concentration analysis suggested that applying magnetic field of 0.3 T during nanoparticle synthesis leads to higher concentration. Applying magnetic field led to an eleven percent increase in the concentration of the colloid with gold nanoparticles and a five percent increase in the concentration of the colloidal silver nanoparticles. The absorption spectra suggested the presence of spherical nanoparticles. When analyzing the effect of the magnetic field on the hydrodynamic size distribution of the nanoparticles and the zeta potential of the colloids, no significant changes were evidenced. The magnetic confinement of the plasma induced by laser ablation caused changes in the characteristics of the colloids.

Coloides con nanopartículas esféricas de plata fueron obtenidos por la técnica de ablación con láser pulsado en líquidos. Los parámetros del láser para la síntesis fueron: longitud de onda de 1064 nm, duración de pulso láser de 10 ns, energía por pulso de 15.7 mJ, 2400, 3600 y 4800 pulsos láser. La radiación láser infrarroja fue enfocada por una lente convergente sobre la superficie de un blanco de plata sumergido en agua desionizada. Para la síntesis de los coloides se utilizó el modo de disparo manual de láser. Cada coloide sintetizado (muestra referencia) fue post irradiado con el mismo láser considerado para la síntesis, pero con energía incidente de 8.3 mJ. Para la post irradiación se consideró una razón de repetición de 10 Hz y diferentes números de pulsos. Durante la post irradiación, el rompimiento óptico del coloide se produjo a mitad de altura del mismo. La caracterización de los coloides se realizó con las técnicas de espectroscopia ultravioleta-visible y microscopia electrónica de barrido. Las curvas para el máximo de absorción y la integral del espectro de absorción en el intervalo correspondiente al infrarrojo cercano (desde 600 nm a 800 nm) sugieren que conforme se incrementó el número de pulsos láser considerados para la post irradiación de una muestra referencia, se presentó: ablación y fragmentación denanopartículas hasta un tamaño crítico, agregación, aglomeración y sedimentación de nanopartículas. Se encontró una dependencia entre las propiedades ópticas de nanopartículas de plata con las condiciones de síntesis y post irradiación de coloides con láser pulsado y enfocado.

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