Ronaldo Herrera-Urbina

Self-alignment of silver nanoparticles in highly ordered 2D arrays.

We have synthesized silver nanoparticles in the non-polar phase of non-aqueous microemulsions. The nanocrystals have been grown by reducing silver ions in the microemulsion cylindrical micelles formed by the reducing agent (ethylene glycol). By a careful deposit of the microemulsion phase on a substrate, the micelles align in a hexagonal geometry, thus forming a 2D array of parallel strings of individual silver nanoparticles on the substrate. The microemulsions are the ternary system of anionic surfactant, non-polar solvent (isooctane), and solvent polar (ethylene glycol); the size of synthesized nanoparticles is about 7 nm and they are monodisperse. The study of the microstructure was realized by transmission electron microscopy, high-resolution technique transmission electron microscopy (HR-TEM), and Fourier processing using the software Digital Micrograph for the determination of the crystalline structure of the HR-TEM images of the nanocrystals; chemical composition was determined using the energy-dispersive X-ray spectroscopy. Addition technique polarizing light microscopy allowed the observation of the hexagonal phase of the system. This method of synthesis and self-alignment could be useful for the preparation of patterned materials at the nanometer scale.

Physicochemical properties of wheat gluten proteins modified by protease from sierra (Scomberomorus sierra) fish.

The effect of semi-purified trypsin on the physicochemical properties of durum and bread wheat flour and gluten protein fractions was evaluated. Trypsin was partially isolated from sierra (Scomberomorus sierra) guts extracts by affinity chromatography. Treatment with enzyme caused hydrolysis of 1.16–1.40% in both durum and bread wheat gluten and gluten fractions. The effect of hydrolysis on the isoelectric point was more evident in durum that bread wheat gluten. Addition of the trypsin-like enzyme at three different concentrations induced a decrease in the gluten index. The dough consistency fell after 1.5 h of incubation. It was possible to modify wheat flour proteins by varying S. sierra trypsin-like enzyme concentration and incubation time, depending on the wheat species.

CO2 adsorption on agricultural biomass combustion ashes

Carbon capture and storage has become an alternative means of confronting global warming. Further research and development into adequate and low-cost materials is required for CO2 adsorption technologies.Samples of fly ash, bottom ash and their respective pellets, produced from wheat bran combustion, were characterized and tested to assess their capacity for CO2 adsorption at different temperatures. Neither the ashes nor their pellets were subject to prior thermochemical activation.The bottom ash sample and its pellets showed a higher adsorption capacity for the majority of the temperatures studied. The pelletized bottom ash reached the maximum adsorption capacity (0,07 mmol CO2/g), followed by the non-pelletized bottom ash (0,06 mmol CO2/g); both at an adsorption temperature of 25°C.CO2 adsorption of bottom ash, from the combustion of wheat bran (agricultural biomass), by a physical adsorption mechanism was demonstrated whereas with the fly ash sample, CO2 adsorption by both physical and chemical adsorption mechanisms was identified.