In this research, the bio-oxidative capacity of three acidophilic bacterial strains (Acidithiobacillus thiooxidans, Leptospirillum ferriphilum, and an unidentified native consortium) are analyzed through the dissolution of cyanicidal species in a polymetallic sulfide mineral mainly composed of pyrite, quartz, sphalerite, and chalcocite. The main objective is the reduction in the amount of sodium cyanide used for the recovery of Au and Ag for the improvement of economic and environmental benefits in the processing of these minerals. Additionally, through a 2³ factorial experimental design, the effect of pH and pulp density (%) on bio-oxidation is evaluated. The results reveal that the bio-oxidation process of the mineral sulfide concentrate has been favored at low pH values and pulp density, favoring Cu species above all dissolution, which form stable complexes with cyanide, leading to excessive cyanide consumption. Therefore, at pH = 1.0 and pulp density of 10%, the catalytic activity of Acidithiobacillus thiooxidans achieves 73.30% Cu, 19.92% Pb, 57.37% Zn, and 25.17% Fe dissolution at the flask level and 83.18% Cu, 12.18% Pb, 55.36% Zn, and 40.98% Fe dissolution at the bioreactor level, allowing the dissolution of 89.5% and 80.4% of Au and Ag, respectively.

Hemp is a material with multiple uses, one of them being construction; making bricks with this material represents a viable alternative to replacing hand-made bricks and thus avoiding the emission of polluting gases in the firing process. The general objective was to evaluate hemp fiber formulations for the compressive strength of an ecological brick versus handmade clay bricks, physically and mechanically characterizing the different formulations that allow for better compressive strength by adding nopal mucilage. In the methodology, compression tests were carried out following the guidelines of NMX-C-036-ONNCCE-2013, for the absorption tests NMX-C-037-ONNCCE-2013; in addition, specific heat and pH tests were carried out, the results obtained show that the hemp formulations have a higher resistance to compression, in terms of pH, the results were 14.82, considered basic, which results in good cohesion between the materials, and finally the specific heat was low between 0.14 and 0.18 MJ/kg, which makes it a good insulator as it conducts very little heat. In conclusion, hemp bricks proved to be a viable alternative to replace traditional clay bricks, not only because they have better characteristics, but also because of the environmental benefits they offer.

This study evaluated the effects of nitrogen source, temperature, and agitation on fermentation performance and volatile compound formation in an agave juice-based beverage fermented with Saccharomyces cerevisiae. Agave juice contained a high concentration of reducing sugars (156.69 g/L), representing 83.16% of the total sugars, predominantly fructose, and a low assimilable nitrogen concentration (0.069 g/L), indicating nitrogen limitation. Fermentation assays were performed at 18 and 28 °C under static or agitated (100 rpm) conditions, with inorganic or organic nitrogen supplementation. At 28 °C, organic nitrogen supplementation under static conditions increased ethanol production to 72.26 g/L. At 18 °C, fermentation kinetics were markedly slower, but nitrogen supplementation increased ethanol production from 34.25 g/L in the control to 59.89 g/L with inorganic nitrogen, indicating that nitrogen supplementation had a greater relative effect under low-temperature fermentation. Volatile profiling revealed that under static fermentation at 18 °C, organic nitrogen supplementation increased the relative abundance of higher alcohols, particularly 2-phenylethanol, whereas ester formation varied according to both nitrogen source and fermentation temperature. Overall, nitrogen source, agitation and temperature strongly affected both fermentation efficiency and volatile formation, supporting the design of controlled processes to improve aromatic complexity and performance in agave-based fermented beverages.