Fernando Salas-Martínez

The presence of pharmaceutical compounds in aquatic systems represents a growing concern due to their persistence and potential adverse effects on ecosystems and human health. In this study, activated carbon obtained from Hordeum vulgare residues was developed and evaluated for the removal of paracetamol from aqueous solutions. The adsorbents were prepared through carbonization followed by physical activation with CO₂ at 800 °C. Their textural and chemical properties were characterized using BET, FTIR, SEM-EDX, and Boehm titration. The activation process significantly increased the surface area (up to 520 m² g⁻¹) and promoted the formation of a micro-mesoporous structure. Adsorption experiments were conducted at pH values of 5–7 and temperatures of 30–40 °C, using an adsorbent dosage of 1 g L⁻¹ and initial concentrations ranging from 100 to 500 mg L⁻¹. The highest experimental adsorption capacity (Qe) (363.84 mg g⁻¹) was obtained at pH 5 and 40 °C, with a removal efficiency of 68.81%. This value exceeded the adsorption capacity reported for activated carbon derived from jatoba fruits and Merck activated carbon by 8.81% and 21.91%, respectively. Nevertheless, neither pH (p = 0.629) nor temperature (p = 0.681) exerted a statistically significant effect on adsorption capacity. The equilibrium data were better fitted by the Freundlich model (R² > 0.93), indicating a heterogeneous surface and multilayer adsorption. These results demonstrate that activated carbon derived from Hordeum vulgare is an efficient and sustainable adsorbent for the removal of emerging contaminants from water, highlighting its potential for biomass valorization.

Phosphorus (P) accumulation in intensively agricultural soils represents a growing environmental concern due to its potential mobilization and contribution to eutrophication. This study investigated the mechanisms controlling P availability and redistribution in agricultural soils from the Elota–Piaxtla Irrigation District (northwestern Mexico) during cropping and non-cropping periods. Soil P fractions were determined using the Hedley sequential extraction method and related to soil physicochemical properties through a correlation analysis. During the cropping period, P in Fe/Al hydroxides dominated (45–67% of total P), indicating strong adsorption and fixation in fine-textured soils. In contrast, the non-cropping period showed a significant increase in organic P in humic substances (up to 55%), suggesting enhanced biological transformation and residue recycling. Labile P fractions decreased from 60% to 44% of total P between sampling periods, while moderately labile fractions increased, indicating seasonal redistribution of P pools. Statistical analysis revealed that P dynamics were primarily governed by mineralogical characteristics and organic matter transformations rather than by individual soil properties. The accumulation of moderately labile and organic P fractions during fallow periods highlights a latent environmental risk, particularly in irrigated systems prone to runoff and erosion. These findings emphasize the need for fraction-based nutrient management strategies that integrate both agronomic efficiency and environmental protection in intensive agricultural soil.

Coffee plantations are highly vulnerable to climatic factors. In this regard, the vulnerability of coffee agroecosystems to extreme hydrometeorological events has been underexplored. This research proposes a method to assess coffee plantations’ vulnerability to five phenomena that have led to disaster declarations in the municipalities where they are cultivated: extreme rainfall, tropical cyclones, floods, snow and low temperatures, and drought. This study considered coffee production, local climate information, hydrometeorological records, and environmental protection actions, spanning 22 years in the eastern state of Veracruz, Mexico. All data were normalized and evaluated for three production values: harvested area ratio, yield, and volume. The Exposition accounted for the number of events, correlating production data with phenomena to assess sensitivity, while the adaptive capacity was assessed by considering environmental protection actions. The results indicated that the most frequent phenomena were extreme rainfall, followed by tropical cyclones, snow and low temperatures, droughts, and floods. However, tropical cyclones accounted for the highest number of vulnerabilities, and drought caused the highest level of vulnerabilities. Snow and cold temperatures reduced vulnerabilities, and floods have non-statistical effects. In general, coffee agroecosystems have a low vulnerability index (6.21 on a scale of 15) due to their location within the local forest.

Acetaminophen, more commonly known as paracetamol (APAP), is one of the most widely used analgesics and antipyretic drugs worldwide. Its presence in the environment poses a risk to the organisms it comes into contact with, which is why it has been classified as an emerging contaminant. Given its adverse effects and continuous discharge into water bodies, it is necessary to study efficient, environmentally sustainable processes for its complete removal. Denitrification is a biological process that has been studied for the biodegradation of recalcitrant compounds and certain pharmaceuticals such as 17β-estradiol and ampicillin, transforming them into harmless products such as N₂ and HCO₃⁻. In the present study, the biodegradation of 6 mg L⁻¹ of APAP-C was evaluated through a denitrifying process. Batch experiments were conducted, achieving acetaminophen (APAP) removal efficiencies (E_APAP-C) of 83.3 ± 0.86% and nitrate removal efficiencies (E_N-NO3⁻) of 100%. The substrates were predominantly converted into HCO₃⁻ and N₂, with yields greater than 0.9, while intermediates such as NO₂⁻ were observed only transiently during the reaction. At the end of the experimental period, no secondary metabolites were detected, indicating that intermediates did not accumulate to quantifiable levels.

En este artículo se presenta una aplicación educativa interactiva para el aprendizaje de un corpus de palabras de la lengua indígena náhuatl, haciendo uso de redes neuronales con memoria a largo y corto plazo (LSTM). El objetivo de la aplicación basada en redes neuronales es el desarrollo de un traductor náhuatl–español, con el fin de preservar y promover la lengua indígena. La aplicación ofrece una herramienta educativa accesible y moderna, utilizando tecnologías innovadoras como las redes neuronales para facilitar la comprensión y traducción de palabras, así como la difusión de aspectos históricos y culturales asociados con la lengua náhuatl. El corpus de palabras incluye saludos, integrantes de la familia, frutas, animales y partes del cuerpo, los cuales conforman una base de datos capaz de ser traducida en la aplicación. Una vez aprendidas, las palabras del corpus pueden aplicarse y utilizarse en el desarrollo de diversos juegos. La interfaz de usuario fue diseñada para ser intuitiva y atractiva, ofreciendo contenidos que van desde información histórica hasta juegos como un memorama y el juego del ahorcado. Para la evaluación del aprendizaje, se aplicaron instrumentos que permitieron medir el conocimiento inicial del lenguaje náhuatl (pretest) y el conocimiento adquirido al final de las actividades (postest). Asimismo, se evaluaron la efectividad de la aplicación y la experiencia del usuario mediante una escala de usabilidad percibida, así como la ergonomía del sistema. Finalmente, la aplicación fue puesta a prueba con alumnos de primaria, quienes aprendieron de manera constructiva e interactiva el corpus de palabras mediante los juegos mencionados.

In recent years, the recording of fish with vertebral malformations has attracted growing interest worldwide, as these malformations may be associated with exposure to xenobiotics. This study aimed to determine the presence and concentrations of pesticide residues (organochlorines and organophosphates) in coastal fish in Nayarit, Mexico, and to assess their potential association with vertebral malformations. From November 2013 to September 2021, 32 fish, with visible malformations were conveniently collected, an equal number of healthy specimens per species was selected for comparative analysis. The fish exhibited vertebral malformations of the following types: kyphosis, lordosis, and scoliosis in 9, 8 and 6 species, respectively, while the total number of malformations was higher across the sampled organisms. Furthermore, pesticide residues were detected in both healthy and malformed fish using gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). The samples analyzed contained at least one pesticide, with the group of healthy fish showing greater diversity of organochlorine compounds. The most frequent of these were p,p’-DDE, followed by p,p’-DDT (41%), p,p’-DDD (25%), and endrin (25%). The species C. raredonae and A. seemanni exhibited the greatest number of pesticides. The pesticides observed in malformed fish samples were p,p’-DDE (100%), p,p’-DDD (97%), p,p’-DDT (97%), endrin (50%), and BHC delta (31%). Chlorpyrifos was present (56% and 100% in healthy and malformed fish), with the highest frequency observed in A. seemanni and B. panamensis. The highest concentrations were observed in the DDT group. An association was also observed between vertebral malformations and concentrations of p,p’-DDE and chlorpyrifos in the species C. raredonae and A. guatemalensis. Multivariate analysis revealed a clear separation between malformed and healthy fish based on contaminant profiles.

La enseñanza de la tabla periódica presenta retos debido a su carácter abstracto y memorístico, lo que reduce la motivación de los estudiantes. Este artículo describe el desarrollo de una aplicación de realidad virtual que transforma la tabla periódica tradicional en un entorno tridimensional interactivo, diseñada en Unity y estructurada bajo la Metodología para el Desarrollo de Espacios Educativos de Realidad Virtual (MEDEERV). El proyecto se encuentra en fase piloto, centrada en el diseño y modelado del entorno, lo que permitió construir una representación inmersiva con elementos interactivos y paneles informativos. A través de una encuesta aplicada a estudiantes y docentes de la Universidad Autónoma del Estado de Hidalgo, de las licenciaturas en Ciencias Computacionales y licenciatura en Química, se identificó un alto interés en el uso de la realidad virtual para la enseñanza de la química y una percepción positiva respecto a la pertinencia de la herramienta. No obstante, una limitación de este estudio radica en que aún no se han realizado pruebas de usabilidad y funcionalidad completas, por lo que los resultados deben considerarse preliminares. Este trabajo contribuye a sentar las bases para futuras investigaciones que integren validaciones experimentales más robustas y evalúen el impacto de la herramienta en la comprensión y motivación de los estudiantes.

Soils are the largest terrestrial carbon (C) reservoirs and play a key role in regulating the global C cycle and supporting essential ecosystem services. Soil C sequestration is a viable strategy to reduce atmospheric CO₂ concentrations and mitigate climate change. This study quantified soil C fractions and litter C stocks across five vegetation types in El Chico National Park, Hidalgo, Mexico (2015.55 ha): pine–oak, oyamel–oak, cedar, oyamel–Tlaxcal, and oyamel forests, all occurring under comparable climatic and edaphic conditions. Soil organic matter (SOM) was quantified as the organic fraction originating from decomposed plant and animal residues. No statistically significant differences (p > 0.05) were found among vegetation types for organic matter, total C, oxidizable C, or recalcitrant (non-oxidizable) C, indicating relative homogeneity across strata. Significant differences (p < 0.05) were detected in organo-mineral C (Cp) and poorly oxidizable C (Cdox), with oyamel–Tlaxcal and oyamel forests showing the highest values, respectively, suggesting enhanced potential for C stabilization and turnover. Oyamel forests stored 32.94% of total soil organic C and contributed disproportionately to park-wide C stocks given their dominance (85.6% of the total area). Leaf litter contained on average 6.60 Mg C ha⁻¹, representing 13,302.63 Mg C and 48,836.8 Mg CO₂ across the park. When integrated with soil C to 60 cm depth, total C and CO₂ stocks reached 643,474.26 Mg and 2,361,566.66 Mg, respectively. These findings highlight the critical role of oyamel forests as the main carbon sink in the park and reinforce the importance of conserving these ecosystems as a nature-based solution for climate change mitigation.

El proceso Foto-Fenton es una alternativa prometedora para la eliminación de contaminantes orgánicos en agua residual, no obstante, está limitado a un pH de trabajo de 3-4. Por ello, se han estudiado metales de transición como el Mn que no limiten el desempeño del proceso. El objetivo del presente trabajo consistió en evaluar el proceso foto-Fenton con Mn (II) para la degradación de contaminantes en agua residual. Se realizaron ensayos Mn (10 - 100 mg L-1) y H2O2 (150 - 600 mg L-1) con relaciones Fe/Mn de 0.2, 0.5, 0.7 y 1, y agua residual al 10, 20, 40, 60, 80 y 100 %. Se logró eliminar la mayor cantidad de contaminantes del agua residual en ensayos con 50 mg L-1 de Mn2+ y 600 mg L-1 de H2O2. En los ensayos con Fe/Mn igual a 0.7, se obtuvieron las mayores degradaciones de contaminantes. El ion Mn2+ actuó como co-catalizador en el sistema foto-Fenton, mejorando el mecanismo clásico con Fe2+.

The concentration of air pollutants could be affected by climate change in industrial park zones in Hidalgo state, Mexico (IPHSs). The goals of this work were: (a) to describe the aerosols’ behavior (PM₁₀ and PM_2.5) and air pollutants (SO₂, NO₂, O₃, and CO) in the IPHSs and (b) determine the climate variable behavior regarding the presence in IPHSs. The methodology consisted of structuring the time series of climate variables and air pollutants in six analysis regions. Afterwards, an annual average calculation, a count of days exceeding the allowed limits set by the official Mexican norms, an analysis of annual behavior by season, the Sen slope calculation, and correlation among variables were performed. Results demonstrated that Zone 2 is the most polluted, exceeding the allowed limits in the annual average (PM₁₀ > 36 μg/m³, PM_2.5 > 10 μg/m³, and NO₂ > 0.021 ppm) and having more than 1000, 96, and 11 days where the daily limit was exceeded in PM₁₀, PM_2.5, and SO₂, respectively. The minimum concentrations of the pollutants were observed during the summer–autumn seasons, coinciding with the highest precipitation. Regarding the correlations, the pollutants are negatively and statistically significantly correlated with precipitation (ranging from −0.81 to −0.43); meanwhile, the maximum temperature (ranging from +0.41 to +0.51) and evaporation (ranging from +0.39 to +0.54) are positively and statistically significantly correlated. In conclusion, the results could suggest that the presence of pollutants in the atmosphere may be influenced by the behavior of nearby regional climatic conditions in the IPHSs.