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The synthesis of silver nanoparticles (AgNPs) using natural extracts is a process that has already been studied due to their excellent antimicrobial activity. However, in most cases, it has been found that the preparation of these nanoparticles leads to the formation of silver chloride (AgCl) as an undesirable side product, which is difficult to remove. In this paper, the AgNPs were prepared using the extract of the sugar industry waste, sugar cane bagasse, as a reducing and capping agent, by a soxhlet extraction system. It was observed that varying the pH of the reaction medium it was possible to avoid the formation of AgCl and in addition, the pH has an important role in controlling the particle size and dispersion. Uv–vis absorption, FTIR, DRX, SEM, TEM and DLS techniques were used to characterize these particles. In addition, a good antimicrobial activity was observed when AgNPs were used against Escherichia coli, Pseudomonas aeruginosa (both Gram negative bacteria) and Staphylococcus aureus (Gram positive bacteria), obtaining better results with the Gram negative.

Cobalt ferrite nanoparticles were synthetized by co-precipitation technique from nitrate precursors. X-ray diffraction confirms the formation of the spinel ferrite. SEM and HRTEM micrographs corroborate the formation of agglomerated nanoparticles of 8–35 nm size range with 21.7 nm average size. The broad size distribution and considerable agglomeration of the particles hamper the superparamagnetic state of the sample, provoking a weak coercivity at room temperature. In contrast to several other magnetic nanostructures, the ZFC-FC curves of cobalt-ferrite nanoparticles revealed an unusually large magnetostriction, evidenced by larger values of magnetization in their ZFC curves than the FC curves in the measured temperature range 20–375 K. The behavior could be reversed on applying high magnetic fields. However, the maximum of ZFC curve reduces on increasing the applied magnetic field.

Square-shaped macropores produced by electrochemical anodization of n- and p-type Si wafers have been used as centers of nucleation to crystallize VO 2 and ZnO. Substrate roughness dependent formation of different morphologies is revealed in the form of squared particles, spheres, bars and ribbons in the case of VO 2 and hexagonal piles and spheres in the case of ZnO, have been observed.The presence of nano-/micro-metric crystals was studied through field emission scanning electron microscopy and energy dispersive X-ray spectroscopy mapping. Crystal structure of metal oxides was confirmed by micro-Raman spectroscopy. The growth of the different morphologies has been explained in terms of the surface free energy of a bare Si/SiO 2 substrate and its modification originated from the roughness of the surface and of the walls of the porous substrates. This energy plays a crucial role on the minimization of the required energy to induce heterogeneous nucleation and crystal growth. Present work strengthens and provides an experimental evidence of roughness dependent metal oxide crystal growth with well-defined habits from pore corners and rough sides of the pore walls, similar to already reported protein crystals.

TiO2is one of the most widely studied oxide materials for applications related to photocatalytic processes. It has been reported that TiO2combined with CdS produces an improvement in the photocatalytic efficiency. This work focuses on the obtainment of TiO2, CdS and TiO2-CdSin situthin films by the sol-gel/dip coating method. After deposition on glass, each film was calcined at 300oC in an argon atmospherefor 30 min. The films were characterized by SEM, UV-Vis, XRD and micro-Raman. The TiO2-CdS film showed greater photocatalyticactivity than the CdS film in the photodecomposition of methylene blue illuminated with UV light. The XRD analysis shows no definedcrystal structure of the thin films.