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This study presents a comprehensive life cycle assessment of the production of biofuels from microalgae by hydrothermal liquefaction, focusing on the valorization of CO2 emitted by the cement industry, which represents about 8% of global anthropogenic emissions. The results demonstrate that hydrothermal liquefaction is a promising option for producing biofuels and highlight the importance of understanding its environmental impact in order to ensure its sustainability. OpenLCA 2.6 software was used to analyze the greenhouse gas (GHG) emissions associated with the process, and it was found that it can capture 3.91 kg of CO2 per kg of biofuel produced compared to 0.286 kg of CO2 per kg of fuel emitted by petrochemical diesel. This article also discusses the financial potential of the technology through the reduction in capital costs due to the elimination of taxes and tariffs under the current policies in Colombia, including the benefits of carbon credits, and finds that the classification of these processes as environmental facilitates their implementation at the industrial level. In conclusion, the capital investment can be reduced by about 15% with an estimated MUSD 165, and the project would be profitable, producing around 850 barrels/day of biofuel under a medium scenario with a carbon bond price of 5 USD/ton CO2, capturing an estimated 20% of the CO2 emitted at the Cementos Argos plant in Cartagena, Colombia.

The alarming levels of carbon dioxide (CO2) are an environmental problem that affects the economic growth of the world. CO2 emissions represent penalties and restrictions due to the high carbon footprint. Therefore, sustainable strategies are required to reduce the negative impact that occurs. Among the potential systems for CO2 capture are microalgae. These are defined as photosynthetic microorganisms that use CO2 and sunlight to obtain oxygen (O2) and generate value-added products such as biofuels, among others. Despite the advantages that microalgae may present, there are still technical–economic challenges that limit industrial-scale commercialization and the use of biomass in the production of added-value compounds. Therefore, this study reviews the current state of research on CO2 capture with microalgae, for which bibliometric analysis was used to establish the trends of the subject in terms of scientometric parameters. Technological advances in the use of microalgal biomass were also identified. Additionally, it was possible to establish the different cooperation networks between countries, which showed interactions in the search to reduce CO2 concentrations through microalgae.

This research aims to propose management strategies to mitigate eutrophication caused by inefficient wastewater treatment plants in Colombia. The information analyzed was provided by environmental authorities such as IDEAM, CORANTIOQUIA, and CORNARE in Antioquia, where the average concentrations of phosphorus in wastewater from municipal, livestock, and industrial activities are 5.1, 30.6, and 29.1 mg P/L. The total nitrogen concentrations are 77, 143, and 121 mg N/L, respectively, surpassing the limit concentrations stated by the European Union, the United States, and Mexico, among others, while Colombia has not established its own limits. Including limitations for nutrient concentrations will align Colombia with the 2050 Sustainable Development Goals (SDGs), where microalgae species like Chlorella or Scenedesmus could be used in wastewater treatment systems for municipalities and industries. These microalgae can capture organic matter, nutrients, and greenhouse emissions and reduce the concentrations observed in natural water. They could also be an alternative for capturing heavy metals and some pollutants of emerging concern. In addition to the ecological and social benefits, the algal biomass could be valorized by transforming it into biological products such as fuels, fertilizers, and pigments when micropollutants are not present, reducing operational costs for treatment systems.

Many tropical bird species have restricted elevational distributions, potentially limited by how environmental conditions affect physiological processes. While some studies have examined adult physiology across elevations, relatively little attention has been given to the structure and function of eggshells despite their critical role in regulating gas exchange during the vulnerable embryonic stage. At high elevations, dry air is expected to increase water loss from the egg, and natural selection may favor lower gas conductance to reduce desiccation risk. Structural variation in eggshells, such as increased shell thickness or reduced pore size and density, could serve as a mechanism to regulate gas diffusion. To test for adaptive variation in eggshell traits along elevational gradients, we measured water vapor conductance and used scanning electron microscopy (SEM) to examine eggshell structure in 197 bird species from the Andes. We found that water vapor conductance declined at high elevations across avian communities. However, structural changes in eggshells varied among bird families and did not vary in a predictable way with elevation, suggesting no relationship or divergent adaptive responses to shared selective pressures, particularly in shell thickness, pore density, and pore size. We propose that examining functional and structural eggshell traits can offer insight into species’ elevational limits and inform predictions about their responses to climate change. Along mountain slopes, changes in humidity, air pressure, and temperature can affect physiological processes and constrain where species can live. As a result, plants and animals are often adapted to the specific conditions of their environments. These patterns have been widely studied across organisms, including birds, where researchers have examined metabolic rates and insulating features such as adult plumage. However, less is known about an even more vulnerable stage of life – when individuals cannot move, and development has only just begun. During embryonic development within an egg, a bird depends on a delicate balance with the external environment. Even small environmental changes can disrupt this balance by altering gas exchange through microscopic pores in the eggshell. Oxygen must diffuse inward, while carbon dioxide and water vapor diffuse outward. At high elevations, maintaining this balance becomes more challenging because dry air increases the risk of excessive water loss. Studying eggshell adaptations can provide refined insights into how environmental conditions during the nesting period may constrain species distributions. Ocampo et al. asked whether birds in tropical mountains cope with environmental challenges during nesting by adjusting gas exchange through the eggshell, particularly by reducing water loss at high elevations. They then investigated the mechanisms underlying these adjustments by examining variation in eggshell microstructure across many species, including traits such as thickness and porosity. First, the researchers documented several nests and eggs not previously described by science, particularly from species inhabiting remote regions of the Amazon and the Andes. By examining egg physiology along elevational gradients, they found that high-elevation species lose water at slower rates than lowland species, likely as an adaptation to reduce the risk of desiccation. These findings support the idea that egg physiology may constrain species distributions. They also identified microstructural variation in eggshells across lineages, although further work is needed to clarify the patterns and their functional significance. Overall, the study of Ocampo et al. highlights the importance of considering all life stages when evaluating physiological responses to climate change. Studies of species’ natural history remain essential and, when combined with hypothesis-driven evolutionary ecology, provide a powerful framework for understanding species distributions and improving predictions of their responses to environmental change. These findings may inform ecologists and physiologists, as well as conservation practitioners, land managers, policymakers, and researchers developing bioinspired materials. Realizing these benefits will require translating findings into predictive models and management strategies, alongside further advancing our understanding of eggshell structure.

In this paper we show the way to apply some and analytical and numerical techniques in order to solve the forced Van der Pol oscillator. We illustrate the obtained results with examples. A comparison with Runge–Kutta numerical method is made in order to see the accuracy of the approximated analytical solution.

The Northern Andes, acting both as barrier and corridor, exert strong influence in Neotropical biodiversity. Still, the diversification of foothill taxa inhabiting ecotonal zones between lowland rainforest and montane environments in this region remains poorly understood. We investigated the evolutionary history of Eutoxeres aquila, a hermit hummingbird distributed across Central America, the Chocó, and both Andean slopes. Using mitochondrial DNA (ND2 and cytb), morphometrics, resistance surface analyses, and ecological niche models, we examined the potential roles of topography, connectivity, and climatic oscillations in shaping lineage divergence. Phylogenetic analyses of 59 individuals of Eutoxeres aquila revealed two major clades: 1) an eastern clade (eastern Andean slope–upper Magdalena valley + mid Magdalena valley–Tamá), and 2) a western clade (western slope–N Central cordillera + Panama). Divergence from E. condamini occurred 4.3 million years ago (Mya), while crown E. aquila diversification began 0.9 Mya, coinciding with Pleistocene climate cycles. The Panama lineage diverged from the western slope–N Central cordillera 0.4 Mya, suggesting post‐Isthmus dispersal. Morphometric analyses of 69 museum specimens showed significant bill shape differentiation among regions, broadly consistent with genetic structure. Genetic distances among individuals were weakly correlated with both resistance and geographic (Euclidean) distances. Ecological niche projections indicated expanded connectivity during the mid‐Holocene and LGM, but contraction and fragmentation during the LIG, with downward elevational shifts during colder periods (LGM and mid‐Holocene) and upward shifts during warmer conditions (LIG and present). These models also revealed that 227 500 km2 of long‐term climatic stability areas concentrated mostly in Amazonia and the Chocó. These results highlight recurrent isolation and reconnection of mountain environments as key drivers of foothill diversification and emphasize the importance of ecotonal taxa for understanding Andean evolutionary processes.

Microalgae have been characterized as an effective raw material for obtaining bioproducts from a biorefinery approach. However, production costs limit the large-scale production of microalgae, which makes these processes uncompetitive in the market. Therefore, in the present work, different agricultural fertilizers were evaluated as low-cost culture media for microalgae growth and the use of the biomass for biocrude production. The tests were carried out in three phases: phase I, Laboratory scale 1 L Erlenmeyer (Boeco, Hamburg, Germany) and phase II–III Pilot scale with cylindrical photobioreactors (PBRs) (Atb services S.A.S, Medellin, Colombia) with a capacity of 20 L. In phase I, four commercial fertilizers Crecilizer® (C), Florilizer® (F) (Fertilizer, Bogota, Colombia), AcuaLeaf Macros® (Ma), and AcuaLeaf Micros® (Mi) (Deacua, Medellin, Colombia) were tested separately and in combination (C + Ma, F + M, and Ma + Mi). The most effective treatments (C and F) in phase I were chosen for scale-up during phase II. In phase III, the concentration of the best treatment from phase II was increased. The biomass obtained from the best phase III treatment showed a cultivation medium cost 50% lower than the biomass obtained using Bold’s Basal Medium (BBM). Following each treatment, the harvested biomass was processed via hydrothermal liquefaction (HTL) to yield biocrude. The reduction in culture medium cost contributed to an estimated 40% decrease in the relative biocrude yield cost.

The study of avian nesting biology in North America and Europe has a long history, resulting in an expansive and information-rich literature. In contrast, the tropics have been relatively neglected and, in most ways, we are still at the frontier of exploration. Data about basic nest descriptions and natural history information are still lacking for many Neotropical species; standardization of data collection methods is needed for comparative analyses. Hence, our goals are: (1) motivate a new generation of Neotropical naturalists to collect nesting data by providing basic tips on how to find nests and collect basic data, (2) provide guidelines on how to use and analyze basic data, (3) highlight the importance of collections, (4) describe modern monitoring techniques, and (5) suggest how these data can be used to fill important gaps concerning the breeding biology of tropical birds. Understanding avian nesting biology and the biotic and abiotic factors that influence nesting success is crucial for a better understanding of bird population dynamics and breeding strategies at the community level, and can form the basis for the development of sound conservation measures. El estudio de la biología de anidación de aves en America del Norte y Europa tiene una larga historia, lo que ha resultado en una literatura extensa y rica en información. Por el contrario, los trópicos han sido relativamente poco estudiados y, en la mayoría de los casos, todavía estamos en la frontera de la exploración. Todavía faltan datos sobre descripciones básicas de nidos e información de historia natural para muchas especies neotropicales, ademas necesitamos estandarizar las metodologías y recolección de datos para los análisis comparativos. Por lo tanto, nuestros objetivos son: (1) motivar a una nueva generacion de naturalistas neotropicales a recopilar datos de anidacion proporcionando consejos basicos sobre cómo encontrar nidos y colectar datos básicos, (2) proporcionar pautas sobre cómo usar y analizar datos básicos, (3) resaltar la importancia de las colecciones biológicas, (4) describir las tecnicas modernas de monitoreo, y (5) sugerir cómo se pueden utilizar estos datos para llenar vacíos importantes en la biologia reproductiva de las aves tropicales. Comprender la biología reproductiva de las aves y los factores bióticos y abioticos que influencian el éxito de la anidación es crucial para comprender mejor la dinámica de las poblaciones de aves, las estrategias de reproducción a nivel de comunidad y puede formar la base para el desarrollo de medidas de conservación sólidas.

In this note we present a new special function that behaves like the error function and we provide an approximated accurate closed form for its CDF in terms of both Chèbyshev polynomials of the first kind and the error function. Also we provide its series representation using Padé approximant. We show a convincing numerical evidence about an accuracy of 10-6 for the approximants in the sense of the quadratic mean norm. A similar approach may be applied to other probability distributions, for example, Maxwell–Boltzmann distribution and normal distribution, such that we show its application using both of those distributions.