http://hdl.handle.net/10584/5598 2026-04-16T14:22:00Z http://hdl.handle.net/10584/13969 Taxonomic and functional diversity and ecosystem services provided by dung beetles (scarabaeidae: scarabaeinae): in a landscape in San Jacinto – Bolívar, Colombia Rangel Acosta, Jorge Luis The conservation of tropical forests requires effective measures grounded in an understanding of their diversity and the spatiotemporal dynamics of their communities. To provide useful insights toward this goal, this study used dung beetles as an indicator group to assess how seasonality and habitat modification influence taxonomic and functional diversity, as well as community structure, in a landscape located in San Jacinto, Bolívar (Colombia). Dung beetle communities were sampled across six habitat types (temporary crops, avocado plantations, pasture, secondary forest, forest edge and forest fragments) over the course of one year, encompassing three climatic periods: two wet seasons and one dry season. Taxonomic diversity, abundance, and biomass decreased progressively from the first wet season to the dry season and from forest to more disturbed habitats. Contrary to expectations, functional diversity did not show a clear response to these factors and in some cases remained high in open areas, suggesting that communities may retain functional resilience even in taxonomically simplified habitats. These results emphasize the critical role of forest fragments as biodiversity reservoirs, especially during unfavorable climatic periods. In addition, agroforestry systems such as avocado plantations and regenerating secondary forests showed potential to maintain functionally diverse communities and to facilitate connectivity in fragmented landscapes. 2025-01-01T00:00:00Z http://hdl.handle.net/10584/13873 Análisis geoquímico de la distribución y especiación de mercurio y otros metales pesados en la Ciénaga de Ayapel, Córdoba Olmos Castro, Sharon Dayana Este estudio evaluó la movilidad, distribución y especiación del mercurio (Hg) y otros metales pesados (Pb, Cd, Cr, As, Zn y Cu) en el Complejo Cenagoso de Ayapel durante época seca (marzo de 2024) y húmeda (octubre de 2024), mediante análisis de agua y sedimentos (ICP-MS, DRX, FT-IR), caracterización textural y modelación geoquímica con PHREEQC. En agua superficial, las concentraciones se mantuvieron por debajo de los valores guía de la OMS; sin embargo, el Hg alcanzó 0,001 mg/L en época seca en Escobillas, indicando mayor disponibilidad en estiaje. En época húmeda, Hg, Pb, Cr y Cu disminuyeron notablemente por dilución y mayor oxigenación. El sistema presentó pH ligeramente alcalino y mayor conductividad, TDS y alcalinidad en época seca. En sedimentos, el Hg superó los criterios del CCME en todos los puntos, especialmente en Casco y Escobillas, confirmando al sedimento como principal reservorio, mientras que el Pb permaneció generalmente bajo sus umbrales. La mineralogía estuvo dominada por cuarzo y feldespatos, con óxidos de Fe; el FT-IR evidenció arcillas y materia orgánica como sitios activos de sorción. La fracción fina predominó en época seca, aumentando la retención. La modelación mostró predominio de complejos inorgánicos y sobresaturación de óxidos de Fe, que controlan la adsorción. Las isotermas indican alta afinidad inicial del Hg(II) y una barrera geoquímica eficiente, vulnerable a cambios estacionales. 2025-01-20T00:00:00Z http://hdl.handle.net/10584/13864 Developing of a machine learning force field for sodium-rich silicate systems: a framework for future boron isotope fractionation modelling Patrón Muñoz, Paola Andrea Magma is a mixture of solids, liquids, and volatiles formed by the partial melting of rocks within the Earth’s crust and mantle. Its solid fraction consists mainly of silica minerals such as olivine, pyroxene, amphibole, micas, feldspar, and quartz. The liquid fraction (melt) is composed of mobile ions of the major elements abundant in the Earth’s crust, including Si, O, Al, K, Ca, Na, Fe, and Mg. In addition, magmas contain a volatile phase dominated by gaseous components, primarily water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2), which strongly influence the physical and chemical evolution of magmatic systems (McDonough and Sun, 1995; Lutgens and Tarbuck, 2015; De Hoog and Savov, 2018). When a silica melt is enriched in boron, it forms borosilicate melt, which can crystal lize into minerals such as tourmaline, containing up to 3 wt% of boron (MacGregor et al., 2013).These melts are geochemically significant because boron behaves as a fluid-mobile and isotopically fractionating element during magmatic differentia tion, crystallization and metasomatism (White, 2015; Sharp, 2017; De Hoog and Savov, 2018). This mobility stems from its nature as a moderately incompatible element, which preferentially partitions into melts and volatiles during processes like magmatic differentiation, crystallization and metasomatism (Sharp, 2017). Therefore, boron is a key element for understanding geological processes and has two isotopes 10B and 11B with average relative abundances of 20% and 80%, respectively, which differ by nearly 10% in relative mass (White, 2015; De Hoog and Savov, 2018). This large mass difference makes boron isotopes powerful tracers for geological processes as crustal recycling, mantle evolution and hy drothermal alteration. The isotopic partition of boron is sensitive to parameters such as temperature, pH, and mineral coordination environment, allowing its use as a geothermometer and proxy for magmatic and fluid evolution (Lutgens and Tarbuck, 2015; White, 2015). Boron also plays an important role in industrial and technological material (Bultman et al., 2010; Huang et al., 2021). Its combination with oxygen forms borosilicate glass characterized by low thermal expansion and high chemical stability, making it important for laboratory applications. For exam ple, Pyrex is a company that manufactures laboratory glassware and kitchenware made from borosilicate glasses due to their exceptional thermal resistance and durability (Ren et al., 2017). In the field of electronics, boron serves as a crucial p-type dopant in silicon that is used in transistors and solar cells (Bultman et al., 2010; Ng and Sze, 2007). In addition, borosilicate glasses possess excellent optical transparency and refractive stability, which make them ideal for optical fibers, precision lenses, and display technologies (Belokoneva, 2005; Mutailipu et al., 2020; Huang et al., 2021). 2025-01-01T00:00:00Z http://hdl.handle.net/10584/13859 In vitro/ex vivo fungicide potential of submicron-emulsions prepared from some essential oils of promising plants from colombian Caribbean Region against colletotrichum gloeosporioides and fusarium oxysporum, main damage-causing phytopathogens in yam crops (Dioscorea spp.) in the department of Sucre Castillo Contreras, Osnaider José; Muñoz Acevedo, Amner Yam (Dioscorea spp.) is a key crop of considerable economic and nutritional importance in the rural areas of the Colombian Caribbean, where it provides both a source of food and an alternative livelihood for smalland medium-scale farmers. In 2020, Colombia produced over 420000 tons of yam, of which more than 90% originated from the departments of Bolívar, Córdoba, and Sucre, while ca. 11500 tons were exported to the United States, Central America, the Caribbean, and Europe. Despite its economic significance, yam production in this region has experienced a yield decline of ca. 7.3%, driven by limitations in agronomic practices, adverse weather, restricted access to inputs, and increasing phytosanitary pressures. Among the main constraints are diseases caused by phytopathogenic fungi such as Fusarium oxysporum and Colletotrichum gloeosporioides, responsible for vascular wilt, tuber rot, and anthracnose, which compromise plant physiology, reduce tuber yield and quality, and impose substantial economic burdens on farmers. Traditional disease management relies heavily on synthetic fungicides, particularly benomyl, a broad-spectrum benzimidazole-carbamate fungicide. While effective, benomyl presents significant environmental and health concerns, including aquatic toxicity, soil biota disruption, and potential neurotoxic effects in humans, highlighting the urgent need for safer, sustainable alternatives. In this context, plants and their secondary metabolites [e.g., essential oils (EOs)] emerge as a promising resource for the phytopathogen control (e.g., F. oxysporum and C. gloeosporioides) due to their proven biological potential. Thus, Colombia, being a country with a wealth of plant biodiversity, would offer an abundant source of secondary metabolites (phenols, terpenoids, etc.), many of which have demonstrated potent antifungal activity. Despite these advantages, direct application of EOs in field conditions is often limited by their hydrophobicity, chemical instability, and high volatility, which reduce their bioavailability and efficacy. Advances in formulation technologies (encapsulation and emulsification), particularly at submicron levels, offer a solution to these limitations. For example, emulsions, such as colloidal systems, can be prepared as nano- or mini-emulsions, with droplet sizes ranging from a few nanometers to several hundred nanometers, using high- or low-energy techniques, including ultrasonication. These formulations enhance EO solubility in water, improve chemical stability, and increase biological activity, enabling more effective field application. In addition, the incorporation of other components into the emulsions such as mediumchain triglycerides (MCTs), can prevent destabilizing phenomena like Ostwald ripening and coalescence, prolonging the functional lifespan of EO emulsions while probably maintaining antifungal effectiveness at the same time. This doctorate research focused on the in vitro and/or ex vivo antifungal potential of EOs and their submicron emulsions against F. oxysporum and/or C. gloeosporioides isolated from yam tubers, with the aim to provide a sustainable alternative for the management of fungal disease in yam crops. The study encompassed: (i) chemical characterization of EOs via GC-FID/MS; (ii) evaluation of in vitro antifungal activity through disk diffusion and broth microdilution assays; (iii) optimization and preparation of submicron-emulsions, with or without MCT, using response surface methodology; (iv) assessment of cytotoxicity on human erythrocytes; (v) multivariate statistical analysis to correlate chemical composition and biological activity; and (vi) ex vivo validation on yam tubers for some emulsions. By integrating natural product chemistry, advanced formulation techniques, and rigorous biological assessment, this work seeks to develop environmentally safe, effective, and practical strategies to mitigate fungal diseases in yam, supporting both agricultural productivity and ecological sustainability. 2025-01-01T00:00:00Z