No abstract

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.

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.