Ismael Enrique Piñeres Ariza

The accumulation of shipwrecked wood in coastal ecosystems represents an important environmental challenge due to its effects on coastal dynamics, ecosystem functioning, and waste management. The valorization of this lignocellulosic residue through thermochemical conversion offers a sustainable alternative for transforming an underutilized biomass into value-added products. This study evaluated the potential of biochar produced from shipwrecked wood collected in the Punta Roca sector, municipality of Puerto Colombia (Atlántico), as an organic soil amendment. The methodology included the physicochemical characterization of the biochar, as well as analysis of its specific surface area (BET), morphology (SEM), and elemental composition (EDAX). Among the most relevant physicochemical results, the biochar exhibited an organic matter content of 87.85%, an alkaline pH of 10.29, and low moisture content (9.21%), suggesting stability and the capacity to modify soil acidity. Regarding specific surface area, the BET area increased significantly from 0.77 m²/g in untreated wood to 61.61 m²/g in the biochar, indicating a notable enhancement in adsorption capacity. Porosity analysis revealed a decrease in pore size, which may favor the retention of nutrients and water. Elemental composition analysis revealed a high carbon content (82.65%) and oxygen content (15.32%), accompanied by trace amounts of elements such as Na, Mg, Si, Cl, K, and Ca. These results confirm that biochar derived from shipwrecked wood possesses physicochemical characteristics suitable for application as an organic amendment in agricultural soils. Overall, these findings demonstrate that biochar derived from shipwrecked wood is a promising alternative not only as an organic soil amendment but also as a strategy for coastal waste valorization, the promotion of circular economy principles, and the development of more sustainable agricultural systems.

Currently, reported estimates indicate that there are 1.03 million annual cases of leptospirosis, with 58,900 deaths worldwide. The Pan American Health Organization (PAHO) in 2022 indicates that the febrile symptoms of leptospirosis are similar to other diseases such as influenza and dengue, among other diseases. Therefore, an early and accurate diagnosis of leptospirosis is essential for adequate and rapid treatment. In this study, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy combined with multivariate analysis techniques was employed to classify between healthy controls and leptospirosis positive samples. Spectra from 113 dried blood plasma samples from patients (n = 43 leptospirosis, and n = 80 controls) were analyzed by linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and support vector machine (SVM), combined with genetic algorithm (GA), successive projections algorithm (SPA), and principal component analysis (PCA) for feature selection/extraction. The GA-LDA model showed good sensitivity at 85.71% and specificity at 100% to discriminate both classes. Cross-validation was also performed, with the Venetian blinds method, showing the GA-LDA-CV model with better results in percentage sensitivity (76%), specificity (91%), precision (83%) and acurracy (86%), F-score (0.828), and AUC (0.835), when compared with the results of the preliminary GA-LDA model, and it is possible to rule out the possibility of overfitting of the preliminary GA-LDA model. Suggesting that combined ATR-FTIR spectroscopy with multivariate analysis has great potential to detect biochemical variations produced by the Leptospira pathogen in the blood of infected patients. These findings emerge as a new potential tool for improving leptospirosis diagnosis in the future using a rapid, low-cost, and minimally invasive methodology.

After tooth extraction, bone levels in the alveoli decrease. Using a bone substitute can help minimize this bone loss. The substitute can be sourced from a human or animal donor or synthetically prepared. In this study, we aimed to address the following PICOS question: In patients needing dental alveolar preservation for implant placement, how does alveolar preservation using a bovine hydroxyapatite bone xenograft with collagen compare to a xenograft without collagen in terms of changes in alveolar height and width, bone density, and the characteristics of the bone tissue observed in biopsies taken at 6 months? We evaluated two xenograft-type bone substitutes for preserving post-extraction dental sockets using tomography and microscopy to answer that question. A total of 18 dental alveoli were studied: 11 preserved with a xenograft composed of apatite (InterOss) and 7 with a xenograft composed of apatite–collagen (InterOss Collagen). Tomographic controls were performed at 1 and 6 months, and microscopic studies were performed on 13 samples. The biopsies were examined with scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). A Multivariate Analysis of Variance (MANOVA) was conducted in the statistical analysis, revealing a significant increase in bone density over time (p = 0.04). Specifically, bone density increased from an average of 526.14 HU at 30 days to 721.96 HU at 60 days in collagen-free samples. However, no statistically significant differences in height or width were found between groups. The MANOVA results indicated that the overall model had a low predictive ability for height, width, and density variables (R-squared values were low), likely due to sample size limitations and the complexity of bone tissue dynamics. On the other hand, FTIR analysis revealed the presence of phosphate groups, carbonates, and amides I, II, and III, indicative of inorganic (hydroxyapatite) and organic (type I collagen) materials in the xenografts. TGA and DSC showed high thermal stability, with minimal mass loss below 150 °C. Finally, both xenografts were influential in alveolar bone regeneration after extraction without significant differences. The trend of increasing collagen density suggests an effect that requires further investigation. However, it is recommended that the sample size be increased to enhance the validity of the results.

By means of a thermogravimetric analysis coupled with mass spectroscopy, the catalytic effect of ferrous sulfate on the pyrolysis of African Palm husk (APH) was studied. Thermogravimetric data were adjusted to the distributed activation energy model (DAEM) with four pseudo-components. Ferrous sulfate had a strong influence on the decomposition parameters of the second and fourth pseudo-components of the DAEM, which are identified as hemicellulose and lignin, respectively. The profiles of the signal intensity curves for the selected m/z ratios were successfully modeled using the kinetic parameters obtained by adjusting the thermogravimetric data. It was found that ferrous sulfate promotes the formation of fragments of m/z = 64, 95, and 96, corresponding to molecules, such as SO₂, hydrocarbon ions of general formula [C_nH_2n‑3]⁺, and furfural, respectively. Mediante el análisis termogravimétrico acoplado a espectroscopía de masas, se estudió el efecto catalítico del sulfato ferroso sobre pirólisis del cuesco de Palma Africana (APH). Los datos termogravimétricos se ajustaron al modelo de energía de activación distribuida (DAEM, por sus siglas en inglés) con cuatro pseudocomponentes. El sulfato ferroso tuvo una fuerte influencia en los parámetros de descomposición del segundo y cuarto pseudocomponente del DAEM, que se identifican como hemicelulosa y lignina respectivamente. Los perfiles de las curvas de intensidad de la señal para las relaciones m/z seleccionadas se modelaron con éxito utilizando los parámetros cinéticos obtenidos del ajuste de los datos termogravimétricos. Se encontró que el sulfato ferroso promueve la formación de fragmentos de m/z = 64, 95 y 96, que corresponden a moléculas como SO₂, iones hidrocarburos de fórmula general [C_nH_2n-3]⁺ y furfural respectivamente.

Introducción: El uso de especies exóticas como materias primas en biorrefinerías puede impulsar el desarrollo sostenible de regiones como la Amazonía; sin embargo, se considera pertinente generar más estudios experimentales previos, que permitan evaluar su potencialidad técnica, aplicada en este caso específicamente con la cáscara de Copoazú. Objetivo: El objetivo de este artículo es determinar la cinética de gasificación del carbonizado resultado de la pirólisis de la cáscara de Copoazú. Metodología: En este trabajo se utilizó el análisis termogravimétrico acoplado a espectroscopía de masas (TGMS), para establecer la distribución de los productos de la gasificación y la cinética de la descomposición del carbonizado, subproducto de la pirólisis de las cáscaras de copoazú. La materia prima fue caracterizada por FTIR y se utilizaron tres velocidades de calentamiento diferentes para el proceso termoquímico. Resultados: Los parámetros cinéticos del proceso de gasificación se obtuvieron ajustando los datos experimentales con tres modelos diferentes, obteniéndose un buen ajuste al modelo DAEM con tres conjuntos de reacciones. Conclusiones: Los datos obtenidos pueden utilizarse para modelar las reacciones de gasificación del carbonizado de esta materia prima. La cinética de producción de la mayoría de las moléculas que se detectaron con una abundancia relativa alta se pudo relacionar con las reacciones de descomposición térmica del carbonizado de la cáscara de Copoazú, de acuerdo con el modelo DAEM.

Using simultaneous thermogravimetrical analysis coupled with mass spectroscopy, the pyrolysis of African palm husk, using several heat rates and programs was performed. Seven relations of mass/charge were followed of the evolved gas of the pyrolysis process, fitting the kinetics and the mass spectroscopy signals to the distributed activation energy model (DAEM) with different numbers of pseudo-components. Fitting with four pseudo-components proved to be the best for modeling the thermal degradation process. Kinetic parameters were not affected by the heating rate or program employed, which agrees with other reports for similar biomass. Methane, methanol formaldehyde, furfural were successfully fitted to the DAEM model, nevertheless CO2 and NO2 were not able to be represented by this model due to its production in secondary reactions in gaseous phase.

Recurriendo al uso de la técnica análisis termogravimétrico, se estudió el efecto del sulfato de zinc y del sulfato férrico en el proceso de pirólisis de la lignina a tres velocidades de calentamiento. Se encontró que la pirólisis de la lignina pura se afecta muy poco con el cambio de las velocidad de calentamiento entre 10 y 100 °C/min, lo cual es inesperado por la naturaleza cinética de la pirólisis. La cinética de pirólisis de este componente de la biomasa fue estudiada teniendo en cuenta tres métodos de ajuste: el método diferencial con modelo de orden de reacción n, el método isoconversional y el modelo de distribución de energías de activación, DAEM. Los mejores ajustes, que permitieron calcular parámetros cinéticos aceptables, fueron obtenidos usando el último método. Los resultados evidencian la influencia de los catalizadores y de la velocidad de calentamiento en los procesos de pirólisis de la lignina en presencia de los sulfatos de estudio, que se confirma con la obtención de diferentes parámetros cinéticos. En términos generales, los sulfatos de zinc y férrico retardan el proceso de pirólisis de la lignina. Los resultados sugieren que los sulfatos de zinc y férrico cambian el mecanismo cinético de la pirólisis de la lignina.