Coraquetzali Magdaleno López

La industria avícola representa una de las actividades pecuarias más relevantes económicamente en México, sin embargo, genera grandes volúmenes de residuos, entre ellos las plumas. Debido a su alto contenido de queratina, representan una excelente alternativa para su valorización. Este estudio tuvo como objetivo extraer y caracterizar queratina de plumas de pollo mediante un proceso optimizado de hidrólisis alcalina asistida por ultrasonido. Se empleó un diseño de superficie de respuesta con tres factores: temperatura (30, 52.5 y 75 °C), tiempo de sonicación (60, 105 y 150 min) y concentración de NaOH (1, 3.5 y 6 %). Las condiciones óptimas fueron 75 °C, 150 min y 3.5 % de NaOH, alcanzando 3.28 mg de proteína hidrolizada/mL. La temperatura fue el factor más influyente en la extracción. El análisis por SDS-PAGE mostró fragmentos de 5–25 kDa, característicos de queratina hidrolizada, mientras que el análisis por HPLC identificó 16 aminoácidos, siendo glicina, serina y alanina los más abundantes. El análisis in silico reveló péptidos con potencial actividad biológica como inhibidores de la Dipeptidil Peptidasa IV y de la Enzima Convertidora de la Angiotensina. En conjunto, estos resultados demuestran el potencial de los métodos alternativos de extracción para la revalorización sostenible de los desechos avícolas.

Los contaminantes emergentes constituyen un problema ambiental relevante debido a su presencia creciente en matrices acuáticas y a la limitada regulación para su monitoreo en México. Por ello, el objetivo de esta revisión sistemática fue analizar estudios realizados principalmente en México entre 2010 y 2025 sobre la detección y cuantificación de estos compuestos en agua. Para ello, se revisó literatura científica relacionada con contaminantes farmacéuticos, productos de cuidado personal, plaguicidas, disruptores endocrinos y otros compuestos de interés ambiental. Los resultados muestran que las técnicas más empleadas son la cromatografía líquida acoplada a espectrometría de masas en tándem (LC-MS/MS), la cromatografía de gases acoplada a espectrometría de masas en tándem (GC-MS/MS) y la espectrometría de masas de alta resolución (HRMS). Asimismo, la extracción en fase sólida (SPE) y la microextracción en fase sólida (SPME) destacan como métodos de preconcentración. Sin embargo, se identificó una marcada disparidad metodológica entre regiones e instituciones, lo que limita la comparabilidad de los datos. Por lo tanto, se requiere estandarizar protocolos analíticos, fortalecer redes de colaboración y actualizar la normativa mexicana para mejorar la vigilancia ambiental y la gestión de riesgos.

The effects of key variables on weak-acid-dissociable (WAD) and free cyanide oxidation by ozone injection in gold mine pulp were studied at laboratory scale to find an alternative cyanide treatment. A fractional factorial analysis of five process variables (O₃/O₂ flow, reaction time, NH₄HSO₃ concentration, temperature, and pH) informed a 60-run experimental matrix, in a 1 L cylindrical reactor, with the process variables controlled during the ozone injection. The findings may inform future strategies for safer cyanide management in gold mining processes. Free cyanide is the most toxic form of cyanide. Its oxidation increases with higher O₃/O₂ concentrations, longer exposure time, and higher pH. Maintaining a pH above 7 is crucial. Lower pH values favor the dissociation of cyanide into its toxic, free form. WAD cyanide oxidation depends mainly on the O₃/O₂ concentration, exposure time, and NH₄HSO₃ concentration. Increasing O₃/O₂ and time enhanced both WAD and free cyanide oxidation, while NH₄HSO₃ concentration affected oxidation rates differently. The results show that free cyanide was significantly more oxidized (84.1413%) than WAD cyanide (67.2423%). Controlling the WAD cyanide process yields excellent free cyanide oxidation. This represents ongoing improvement at an industrial scale. This approach quantifies the extent to which process variables affect the WAD and free cyanide oxidation under controlled conditions, thereby greatly reducing environmental impact.

Las nanopartículas de óxidos metálicos se encuentran entre los nanomateriales más utilizados en diversos sectores, como la medicina, la agricultura, la industria alimentaria y los dispositivos electrónicos, debido a sus propiedades funcionales, como gran área superficial, estabilidad química y actividad antimicrobiana. Sin embargo, su creciente producción y uso han incrementado su liberación al medio ambiente, especialmente en ecosistemas acuáticos. Diversos estudios han demostrado que estas NPs pueden inducir efectos tóxicos en organismos acuáticos afectando el equilibrio ecológico. La toxicidad depende de factores como el tipo de óxido metálico, el tamaño de las NPs, la carga superficial y su comportamiento en medios acuosos. En esta revisión se analizan las características fisicoquímicas de las nanopartículas de dióxido de titanio (NPs TiO2), de óxido de zinc (NPs ZnO) y de óxido de cobre (NPs CuO). La revisión resume los mecanismos de acción y la toxicidad asociada con estas NPs con el objetivo de proporcionar una visión general sobre su impacto ecológico y los desafíos actuales en su evaluación y regulación.

This work proposes for the first time protecting–reflecting on both sides of plated mirrors and a solution to polycarbonate surface vulnerability to weathering and scratching using tungsten disulfide (WS₂) by mechanical polishing. The ability of the dynamic chemical plating (DCP) technique to deposit Ag films at the nanometer scale on a polycarbonate (PC) substrate and its characteristics to be metallized is also shown. These deposits hold significant promise for concentrated solar power (CSP) applications. Complementarily, the application of WS₂ as a reflective film for CSP by mechanical polishing on smooth polycarbonate surfaces is both novel and practical. This technique is innovative and scalable without needing reactants or electrical potential, making it highly applicable in real-world scenarios, including, potentially, on-site maintenance. The effects of surface morphology and adhesion, and the reflectivity parameters of the silver metallic surfaces were investigated. Wettability was investigated because it is important for polymeric surfaces in the activation and metal deposition immediately after redox reactions. The flame technique improved wettability by modifying the surface with carbonyl and carboxyl functional groups, with PC among the few industrial polymers that resisted such a part of the process. The change in the chemical composition, roughness, and wettability of the surfaces effectively improved the adhesion between the Ag film and the PC substrate. However, it did not significantly affect the adhesion between PC and WS₂ and showed its possible implementation as a first surface mirror. Overall, this work provides a scalable, innovative method for improving the durability and reflectivity of polycarbonate-based mirrors, with significant implications for CSP applications.

Aims: This work uses the MACE method to synthesize SiNWs- NiNPs/NiONPs to degrade organic pollutants by photocatalysis. Background: Photocatalytic degradation has been applied as an attractive solution to remove several organic pollutants. Heterostructured nanomaterials have become an interesting platform for investigation. Metal-assisted chemical etching (MACE) stands out as a promising technique because it is simple, low cost, and fast. Objective: Attain the degradation of methyl orange (MO) in the presence of silicon nanowires (SiNWs) in heterojunction with Nickel/Nickel Oxide nanoparticles (NiNPs-NiONPs). Methods: SiNWs were synthesized by metal (Ag) assisted chemical etching (MACE) of monocrystalline silicon wafers. NiNPs were non-electrolytically deposited on the SiNWs (electroless method). The morphology of the SiNWs- NiNPs/NiONPs was observed by SEM. Results: Heterogeneous photocatalytic degradation of methyl orange (C14H14N3NaO3S) in an aqueous solution at a concentration of 20 ppm had an efficiency of 66.5% after 180 min under UV irradiation. The MO degradation percentage was determined using UV-visible spectrophotometry. Conclusion: The SiNWs-NiNPs/NiONPs were obtained composed mainly of Si covered by SiO2 decorated on the tips with Ni (II) in the form of NiO and a small amount of nickel metal. The removal efficiency obtained at 180 min of light exposure was 66.5%. After the photocatalysis tests, further oxidation of the NiNPS into NiONPS, was attributed to the reactive oxygen species in the aqueous medium based on the changes of the oxygen and Ni2p3/2 peaks by XPS. Other: Through XPS, the oxidation state of the SiNWs- NiNPs/NiONPs was analyzed.

AISI 304 SS has good corrosion resistance in a variety of environments but does not have good resistance to wear. Aggressive marine environments require materials that can withstand both the biocorrosion and the wear associated with the impact of waves, ocean currents and suspended particles. Oxy-nitriding of stainless steels can be used to increase their hardness and wear resistance. The conventional oxy-nitriding process is lengthy, and the temperature involved can affect the corrosion resistance of the material. To mitigate these problems, it was decided to study an oxy-nitriding process in plasma electrolytic conditions, using aqueous solutions of 20, 30 and 40 wt% urea. The results showed that all the concentrations evaluated gave lower levels of wear than untreated stainless steel. However, considering the amount of urea used and the environmental emissions from the waste generated, a concentration of 20% by weight of urea in the electrolyte is considered sufficient to increase up to three times the wear resistance of stainless steel. XRD, XPS and microscopy analyses showed that, in the main, the outermost layer of the steel surface treated by electrolytic plasma has a morphology of small craters of chromium and iron oxy-nitrides. A nitrogen diffusion layer was also seen below the oxy-nitrided layer.

Geopolymers have been mainly utilized as structural materials; their chemical structure and morphologies have been explored for their potential as a high-performance material in emerging applications. Geopolymer composites reinforced with materials based on agro-waste are attracting interest in engineering applications due to their easy processing, low cost, low density, and high strength-to-weight ratio. This investigation pursues an experimental methodology that consists of a scheme to make composites with a geopolymer matrix and agro-waste (rice husk, barley, and coffee) as aggregate material, that can be applied in various fields of construction. The study was intended to determine the influence of adding various agro-wastes on the mechanical properties of the geopolymer. According to the respective ASTM standards, the materials obtained were prepared and analyzed to determine their compressive strength, flexural strength, hardness and scanning electron microscopy (SEM)-determined characteristics. The results revealed that, for the compression tests, the composites formed by a sol-gel matrix and barley husk showed a better yield, obtaining the highest value of 3.5 N/mm². Concerning hardness testing, the composites with a geopolymer matrix and coffee husks obtained higher values compared to the other composites. For the flexural tests, the compounds with the sol-gel/fly ash matrix obtained the highest yield stress value, which was 5.25 MPa with an elastic modulus of 7.59 GPa. The results of the microstructural analysis showed good husk-matrix interaction, together with failure mechanisms. The conformation of such waste-based compounds may enable them to replace natural wood in some applications, such as in the finishing of interiors of homes, during the final stages in the construction of buildings, or in the decoration of inhabited houses, as well as in finishing in the manufacture of furniture.

The lifetime of mirrors in outdoor conditions is crucial in the correct operation of any concentrating solar power (CSP) installation. In this work, the corrosion behavior of two types of metallized surfaces was studied. The first was made of a flexible polymer having a deposited reflective silver metallic film. The second was made of the same surface type with a dielectric SiO₂ protection coating by an atmospheric pressure plasma jet. Polycarbonate sheets were used as substrates on which metallic silver was deposited by the Dynamic Chemical Deposit technique. This electroless technique allowed producing the mirror finishing under environmental conditions by sequentially spraying; as aerosols projected towards the substrate surface, the activation and reducing-oxidizing solutions with rinsing after each one. The silver coatings were about 100 nm thick. Environmental and accelerated weathering degradation and salt and sulfide fogs were carried out. XPS analyses show that the corrosion products formed were Ag₂S, AgCl, and Ag₂O. It was observed that the tarnishing was initiated locally by the formation of Ag₂S columns as eruptions on the surface. Subsequently, the ions diffused through the protective layer and into the silver reflective layer, chemically reacting with the silver. The main atmospheric agents were H₂S, chloride particles, and HCl. High reflectance was initially obtained of about 95%. The obtained results suggest mechanisms for the degradation of exposed silver surfaces to moisturized atmospheres with corrosive compounds.