Catalytic Decomposition of n-C-7 Asphaltenes Using Tungsten Oxides-Functionalized SiO2 Nanoparticles in Steam/Air Atmospheres

A wide range of technologies are being developed to increase oil recovery, reserves, and perform in situ upgrading of heavy crude oils. In this study, supported tungsten oxide nanoparticles were synthesized, characterized, and evaluated for adsorption and catalytic performance during wet in situ combustion (6% of steam in the air, in volumetric fraction) of n-C-7 asphaltenes. Silica nanoparticles of 30 nm in diameter were synthesized using a sol-gel methodology and functionalized with tungsten oxides, using three different concentrations and calcination temperatures: 1%, 3%, 5% (mass fraction), and 350 degrees C, 450 degrees C, and 650 degrees C, respectively. Equilibrium batch adsorption experiments were carried out at 25 celcius with model solutions of n-C-7 asphaltenes diluted in toluene at concentrations from 100 mg center dot L-1 to 2000 mg center dot L-1, and catalytic wet in situ combustion of adsorbed heavy fractions was carried out by thermogravimetric analysis coupled to FT-IR. The results showed improvements of asphaltenes decomposition by the action of the tungsten oxide nanoparticles due to the reduction in the decomposition temperature of the asphaltenes up to 120 degrees C in comparison with the system in the absence of WOX nanoparticles. Those synthesis parameters, such as temperature and impregnation dosage, play an important role in the adsorptive and catalytic activity of the materials, due to the different WOX-support interactions as were found through XPS. The mixture released during the catalyzed asphaltene decomposition in the wet air atmosphere reveals an increase in light hydrocarbons, methane, and hydrogen content. Hydrogen production was prioritized between 300 and 400 degrees C where, similarly, the reduction of CO, CH4, and the increase in CO2 content, associated with water-gas shift, and methane reforming reactions occur, respectively. The results show that these catalysts can be used either for in situ upgrading of crude oil, or any application where heavy fractions must be transformed

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

Catalytic Decomposition of n-C7 Asphaltenes Using Tungsten Oxides–Functionalized SiO2 Nanoparticles in Steam/Air Atmospheres

A wide range of technologies are being developed to increase oil recovery, reserves, and perform in situ upgrading of heavy crude oils. In this study, supported tungsten oxide nanoparticles were synthesized, characterized, and evaluated for adsorption and catalytic performance during wet in situ combustion (6% of steam in the air, in volumetric fraction) of n-C7 asphaltenes. Silica nanoparticles of 30 nm in diameter were synthesized using a sol–gel methodology and functionalized with tungsten oxides, using three different concentrations and calcination temperatures: 1%, 3%, 5% (mass fraction), and 350 °C, 450 °C, and 650 °C, respectively. Equilibrium batch adsorption experiments were carried out at 25 ℃ with model solutions of n-C7 asphaltenes diluted in toluene at concentrations from 100 mg·L−1 to 2000 mg·L−1, and catalytic wet in situ combustion of adsorbed heavy fractions was carried out by thermogravimetric analysis coupled to FT-IR. The results showed improvements of asphaltenes decomposition by the action of the tungsten oxide nanoparticles due to the reduction in the decomposition temperature of the asphaltenes up to 120 °C in comparison with the system in the absence of WOX nanoparticles. Those synthesis parameters, such as temperature and impregnation dosage, play an important role in the adsorptive and catalytic activity of the materials, due to the different WOX–support interactions as were found through XPS. The mixture released during the catalyzed asphaltene decomposition in the wet air atmosphere reveals an increase in light hydrocarbons, methane, and hydrogen content. Hydrogen production was prioritized between 300 and 400 °C where, similarly, the reduction of CO, CH4, and the increase in CO2 content, associated with water–gas shift, and methane reforming reactions occur, respectively. The results show that these catalysts can be used either for in situ upgrading of crude oil, or any application where heavy fractions must be transformed

Availability of over-the-counter antibiotics in Guatemalan corner stores.

Widespread availability of antibiotics without prescription potentially facilitates overuse and contributes to selection pressure for antimicrobial resistant bacteria. Prior to this study, anecdotal observations in Guatemala identified corner stores as primary antibiotic dispensaries, where people purchase antibiotics without prescriptions. We carried out a cross sectional study to document the number and types of antibiotics available in corner stores, in four study areas in Guatemala. A total of 443 corner stores were surveyed, of which 295 (67%) sold antibiotics. The most commonly available antibiotics were amoxicillin, found in 246/295 (83%) stores, and tetracycline, found in 195/295 (66%) stores. Over the counter sales result from laissez-faire enforcement of antibiotic dispensing regulations in Guatemala combined with patient demand. This study serves as a baseline to document changes in the availability of antibiotics in informal establishments in light of new pharmacy regulations for antibiotic dispensing, which were adopted after this study was completed

Biodiversidad 2017. Estado y tendencias de la biodiversidad continental de Colombia

En la cuarta versión del Reporte, que corresponde al año 2017, es una obligación preguntarnos cuál ha sido y es el papel de esta publicación y si ha abarcado la diversidad de formas y conceptos que definen el estado y el futuro de la biodiversidad colombiana. Las temáticas que constituyen la columna vertebral de cada uno de los reportes anuales responden a temas de pertinencia, nivel de incidencia y actualidad desde cada uno de los diferentes niveles de organización de la biodiversidad y buscan responder las siguientes preguntas fundamentales: 1) ¿Cómo se encuentra la biodiversidad del país? 2)¿Qué factores, en dónde y en qué medida está siendo afectada? 3)¿Cuáles son las iniciativas que desde la sociedad civil o a nivel de políticas públicas buscan evitar esa pérdida? 4)¿Cuáles son las grandes oportunidades para mejorar su gestión y manejo? Si bien evaluar la incidencia que puede tener el Reporte sobre acciones de gestión no es tarea fácil, se debe reconocer la buena acogida que han tenido los textos, las ilustraciones y la cifras entre los distintos tipos de lectores y el papel fundamental que ha jugado el Reporte en comunicar información de altísima calidad sobre la biodiversidad colombiana en diferentes momentos coyunturales. En ese sentido esta publicación es cada vez más una herramienta de consulta y referencia que está abierta al público tanto en formato impreso como digital, y de la misma manera busca fortalecerse para continuar brindando información relevante para la toma de decisiones en materia ambiental.BogotáSubdirección de Investigacione

Consistent patterns of common species across tropical tree communities

International audienceAbstract Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations 1–6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories 7 , we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1–6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Consistent patterns of common species across tropical tree communities

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories , we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Consistent patterns of common species across tropical tree communities

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories , we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Consistent patterns of common species across tropical tree communities

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories , we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees