Mexican Institute of Petroleum

Zero-valent trigonal selenium nanoparticles (SeNPs) were potentiostatically formed at room temperature (298 K) on the surface of a glassy carbon electrode (GCE) from SeO₂ dissolved in ethaline, a deep eutectic solvent composed of choline chloride and ethylene glycol. The mechanisms and kinetics of SeNP electrochemical nucleation and growth on GCE were investigated using both potentiodynamic and potentiostatic techniques. From cyclic voltammetry, the equilibrium potential (Eeq) of the Se(IV)/Se(0) redox couple, the exchange current density (j0), and the charge transfer coefficient (α) for the faradaic reaction Se(IV)ethaline + 4e−GCE/Se(0) $$\rightleftarrows$$ Se(s) were determined to be Eeq = 96 mV vs. Ag QRE, j0 = (1.2 ± 0.1) µA·cm⁻², and α = 0.4 ± 0.1. Analysis of the experimental potentiostatic current density transients (j–t plots) recorded at various overpotentials revealed that the SeNP electrodeposition mechanism involves three consecutive processes: (i) Adsorption and double-layer charging, (ii) Multiple 3D nucleation and diffusion-controlled growth of SeNPs, and (iii) Residual water reduction on the growing SeNP surfaces (2H2ODES + 2e− (Se) $$\rightleftarrows$$ H2(g) + 2OH− (DES)). The applied theoretical model enabled deconvolution of the total j–t response into these individual contributions, allowing for extraction of key kinetic parameters, including the SeNP nucleation frequency (A), the number density of active nucleation sites (N0), and the diffusion coefficient of Se(IV) in ethaline, DSe(IV) (298 K) = (4.91 ± 0.04) x 10− 9 cm2s− 1. Furthermore, from the dependence of A on overpotential, beside j0 and α, additional thermodynamic parameters were determined: the surface energy (σ), the critical nucleus size (nc), and the Gibbs free energy for the formation of the critical nucleus (ΔG(nc)) across the range of applied overpotentials. SEM analysis revealed the formation of smooth, quasi-spherical SeNPs with an average diameter of (118 ± 26) nm, uniformly distributed across the GCE surface. High-resolution XPS spectra recorded in the Se 3d region confirmed the presence of selenium in its zero-valent state. The Raman spectrum displays characteristic signals at 236 and 141 cm⁻¹, indicating that the predominant allotropic form of selenium in the nanoparticles is trigonal Se. Additionally, the optical band gap of the electrodeposited film was estimated using UV–Vis spectroscopy and the Kubelka–Munk method. A band gap of 1.7 eV was obtained, which is consistent with previously reported values for trigonal Se nanoparticles.

Las obstrucciones en ductos petroleros representan un desafío crítico para la operación continua y eficiente del transporte de hidrocarburos. Entre las principales causas se encuentran las biopelículas: comunidades microbianas que se adhieren a las paredes internas de las tuberías y que, con el tiempo, pueden evolucionar hacia estructuras obstructivas. Este artículo explora cómo la simulación de dinámica de fluidos computacional (CFD) permite modelar el crecimiento, la interacción con el flujo y el eventual colapso estructural de dichas biopelículas. Se presenta una descripción de los fundamentos físicos, matemáticos y computacionales utilizados en la modelación, así como de los parámetros relevantes que afectan la estabilidad de la biopelícula como medio poroso. Además, se discute la importancia de anticipar estos fenómenos desde una perspectiva operativa, mediante el uso de simulaciones numéricas como herramientas predictivas. La integración de estos modelos en esquemas de mantenimiento inteligente puede optimizar significativamente las estrategias de prevención de obstrucciones en sistemas de transporte de crudo.

• 2 derivatives were obtained from Quercetin via laccase catalysis • DFT calculations elucidate a supramolecular pair for quercetin • Derivative characterization by theoretical and experimental correlation • Supramolecular structure exhibits greater antioxidant activity than individual ones Phenolic compounds display notable biological activities, including antioxidant, antiproliferative, and anti-inflammatory effects. Among them, quercetin and caffeic acid stand out as promising candidates for pharmaceutical and nutraceutical applications. Nevertheless, their poor water solubility and chemical instability significantly limit their practical use. Previous studies have shown that enzymatic polymerization can enhance the solubility of phenolic compounds; however, the underlying reaction mechanisms and interactions remain only partially understood. In this work, Trametes versicolor laccase was employed to catalyze the modification of quercetin and caffeic acid, leading to the generation of five reaction products, including three supramolecular structures. Spectroscopic (UV-Vis, FT-IR, and ¹H-NMR) and UHPLC-MS analyses confirmed the nature of these products, while molecular modeling provided further structural insights that supported the experimental evidence of supramolecular assembly. Additionally, the antioxidant activity of the reaction products was evaluated to compare it with that of the individual compounds, highlighting the relevance of these structures in biological activities. To our knowledge, this is the first report describing the formation of supramolecular assemblies between quercetin derivatives and caffeic acid mediated by fungal laccase. These findings not only contribute to a deeper mechanistic understanding of phenolic biotransformation but also demonstrate the potential of laccase-catalyzed reactions to generate bioactive supramolecular structures with enhanced properties, thereby opening new opportunities for their application in food, pharmaceutical, and biotechnological fields.

Abstract We present the first micromagnetic simulations for sub‐micron monoclinic 4C pyrrhotite (), a common mineral in rocks and sediments and an important mineral in paleomagnetic studies. Previous experimental studies on the magnetic properties of pyrrhotite had limited control over granulometry and focused primarily on larger, micron‐scale grain sizes. We model particles here with a hexagonal prismatic habit and uniaxial and triaxial basal plane anisotropy in the 5 nm to range. Single domain (SD) structures remain the lowest energy state for particles up to ≈2 μm in size, although it is possible to nucleate multidomain (MD) states in particles as small as 100 nm. MD structures consist of domains aligned within the basal plane separated by Néel walls, often with internal Néel lines; no vortex states are observed. In hysteresis and first‐order reversal curve simulations, sub‐micron pyrrhotite particle magnetizations switch coherently, giving rise to uniaxial‐SD signatures within the basal (001) plane; triaxial switching is not observed because the field step used in our models is too large to visualize the expected signals. Estimated relaxation times predict that hexagonal monoclinic pyrrhotite prisms have a ≈15 nm superparamagnetic threshold size and are geologically stable at sizes above≈20 nm. We find generally good agreement between experimental data and numerical predictions that assume uniaxial basal plane anisotropy, although there is little grain‐size overlap between the two data types, and questions remain regarding the accuracy of experimentally observed material parameters for pyrrhotite.

This study aimed to characterize ovarian follicular dynamics and to describe the ultrasonographic features of early to after-gestation in mares under extensive field conditions. A total of 100 clinically healthy Spanish-type mares, averaging 8 ± 0.7 years of age and 500 ± 50 kg in body weight, were monitored over a 730-day period in three rural locations in Tamaulipas, Mexico. Transrectal ultrasonography was performed daily across a full estrous cycle (~21 days) to assess follicular development in non-pregnant mares. For mares confirmed pregnant 15 days post-mating, five ultrasound evaluations were conducted between days 15 and 150 of gestation. A total of 500 follicular and 500 gestational ultrasonographic images were obtained. Follicles were classified into three groups by diameter: 8–20 mm (n = 250; 50.0%), 21–30 mm (n = 150; 30.0%), and 32–45 mm (n = 100; 20.0%), with mean diameters of 13.7 mm, 25.4 mm, and 39.7 mm, respectively. The mean number of follicles per mare was 5.0, reflecting typical follicular activity during one estrous cycle under tropical field conditions. Gestational scans were distributed as follows: days 15–28 (n = 167; 33.4%; mean age: 21.9 d), days 30–45 (n = 166; 33.2%; mean age: 38.8 d), and days 50–150 (n = 167; 33.4%; mean age: 75.1 d). Key gestational features, such as the embryonic vesicle, heartbeat, and fetal skeleton, were documented per stage. In conclusion, structured ultrasonographic benchmarks for assessing follicular and gestational stages in mares were provided, offering practical tools for reproductive monitoring in field conditions.

Antimicrobial photodynamic inactivation (aPDI) is an emerging alternative for reducing microbial loads in complex matrices such as wastewater. In this work, a porphyrin-dendrimer conjugate (Pf-Ds-G2.0) was synthesized, structurally characterized and evaluated as a photosensitizer under visible light. Pf-Ds-G2.0 generated singlet oxygen with a quantum yield of 0.35 and exhibited light-dependent antimicrobial activity in real wastewater samples. Under visible-light irradiation, Pf-Ds-G2.0 produced moderate reductions in microbial biomass (~ 20% microbial reduction after 6min irradiation), supported by both OD and CFU measurements, while dark controls showed no inhibition. Partial regrowth was observed at longer irradiation times, likely due to oxygen depletion and the heterogeneous nature of the microbial community. These findings demonstrate the potential of dendritic porphyrins for wastewater aPDI and highlight the need for further optimization of irradiation conditions, oxygen availability and sensitizer formulation to achieve more sustained inactivation in complex systems.