Ecología, construcción e innovación: Una alerta al cambio

The environmental damage caused to the planet is largely due to the pollution left behind by the misuse of debris, a large ecological footprint, the deforestation of important spaces due to the need to build, and bad practices within civil engineering. It is known that this problem is worldwide, but the most appropriate in our context and analysis is to focus on Colombia. A secondary objective of this article is to raise awareness and provide possible solutions to a problem as extensive and complicated as pollution. At the end of reading the article, it will be shown that this problem does not only affect a few people but the country in general.El daño ambiental provocado al planeta se produce en gran medida por la contaminación que deja la mala utilización de escombros, una gran huella ecológica, la deforestación de espacios importantes por la necesidad de construir, y las malas prácticas dentro de la ingeniería civil. Se sabe que esta problemática es a nivel mundial, pero lo más adecuado en nuestro contexto y análisis es centrarse en Colombia. Un objetivo secundario de este artículo es la concientización, y dar unas posibles soluciones a un problema tan extenso y tan complicado como lo es la contaminación. Al finalizar de leer el artículo se mostrará que esta problemática no afecta solo a unos cuantos sino al país en general

Synthesis of geopolymers from alkaline activation of gold mining wastes

Resumen Este trabajo presenta los resultados preliminares relacionados con el desarrollo de polímeros inorgánicos (geopolímeros) a partir de la activación alcalina de residuos de la minería de oro. La caracterización mineralógica y fisicoquímica de estos residuos de minería de oro muestra su gran potencial como fuente de precursores geopoliméricos como una alternativa razonable para el desarrollo de aglutinantes activados alcalinamente amigables con el medio ambiente. El proceso de geopolimerización es un camino viable para transformar estos residuos en materiales con alta resistencia mecánica, alta inercia química y alta durabilidad en el tiempo, dando valor agregado a los subproductos de la actividad minera. Abstract This paper reports preliminary results related to the development of inorganic polymers (geopolymers) from alkaliactivation of gold mining wastes. Mineralogical and physicochemical characterization of these gold mining wastes shows their significant potential as geopolymeric source precursors as a reasonable alternative to the development of alkali-activated friendly environmental binders. Geopolymerization process is a viable way to transform these residues in materials with high mechanical strength, high chemical inertness and high durability over time, giving add value to the by-products of the mining industry

Is keV ion induced pattern formation on Si(001) caused by metal impurities?

We present ion beam erosion experiments performed in ultra high vacuum using a differentially pumped ion source and taking care that the ion beam hits the Si(001) sample only. Under these conditions no ion beam patterns form on Si for angles below 45 degrees with respect to the global surface normal using 2 keV Kr ions and fluences of 2 x 10^22 ions/m^2. In fact, the ion beam induces a smoothening of preformed patterns. Simultaneous sputter deposition of stainless steel in this angular range creates a variety of patterns, similar to those previously ascribed to clean ion beam induced destabilization of the surface profile. Only for grazing incidence with incident angles between 60 degrees and 83 degrees pronounced ion beam patterns form. It appears that the angular dependent stability of Si(001) against pattern formation under clean ion beam erosion conditions is related to the angular dependence of the sputtering yield, and not primarily to a curvature dependent yield as invoked frequently in continuum theory models.Comment: 15 pages, 7 figures. This is an author-created, un-copyedited version of an article published in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from i

Modelo predictivo del índice de anisotropía del semicoque a partir de las propiedades de los carbones de la Cordillera Oriental de Colombia

This study developed a theoretical model for the determination of the Coke Anisotropy Quotient (CAQ) of semi-coke from the properties of its precursor coal. This is an useful parameter to define the resistance and reactivity of semi-coke in the blast furnace. For 36 semi-coke samples, a textural analysis was performed alongside a fluidity test to determine the real CAQ. The main textures observed were: isotropic and circular for high volatile bituminous coals (HVB); lenticular and fine ribbons for the medium volatile bituminous coals (MVB); and medium and thick ribbons for the low volatile bituminous coals (LVB). The CAQ varied in a range from 1 to 11. A principal component analysis (PCA) and multiple regression allowed to discriminated the importance of certain coal properties, in determining the CAQ to be recognized and to estimate parameters of the mathematical model. The statistical analysis suggested that CAQ can be best predicted from the fluidity, volatile matter, and Ro of the parent coals. The veracity of this model result was then tested using a second dataset from Poland. This work optimizes the usefulness of standard datasets in the prediction of CAQ's offering a means of quality control that could be implemented in Colombian coke production.En esta investigación se desarrolló un modelo teórico para la determinación del Cociente de Anisotropía del Coque (CAQ) del semicoque a partir de las propiedades de su carbón precursor. El CAQ permite definir la resistencia y la reactividad del semicoque en el alto horno. Usando material residual de las pruebas de fluidez se realizó un análisis textural para determinar el CAQ real sobre 36 muestras de semicoque. Las principales texturas observadas para los carbones bituminosos fueron: isotrópicas y circulares para los de alta volatilidad (HVB); cintas lenticulares y finas para los de media volatilidad (MVB); y cintas medias y gruesas para los de baja volatilidad (LVB). El CAQ varió en un rango de 1 a 11. Análisis de componentes principales (PCA) y regresión múltiple permitieron reconocer la importancia de ciertas propiedades del carbón para determinar el CAQ. El análisis estadístico sugirió que el CAQ puede predecirse mejor a partir de la fluidez,la materia volátil y el Ro de los carbones precursores. Este modelo fue validado a través de la comparación con datos reales de carbones de Polonia. Este trabajo proporciona un medio de control de calidad que podríaimplementarse en la producción de coque colombiano.&nbsp

The use of an industrial mineral waste as catalyst in the hydroconversion of dibenzylether and a colombian subbituminous coal

Un residuo mineral industrial, proveniente de la producción de sulfato de aluminio, se utilizó como precursor para la preparación de un catalizador de bajo costo, activo en reacciones de hidroconversión de dibenciléter, como compuesto modelo de las uniones C-O en el carbón, y de un carbón subbtituminoso colombiano. El residuo mineral y un óxido de hierro comercial (material de referencia) se sometieron a un proceso de sulfuración con el propósito de generar un sulfuro de hierro tipo pirrotita (Fe1-xS), el cual es la fase activa del hierro en reacciones de hidroconversión. Los sólidos se caracterizaron por difracción de rayos X, fluorescencia de rayos X, espectroscopía Raman y microscopía electrónica de barrido. Las pruebas de actividad catalítica, con el compuesto modelo y el carbón, se realizaron a 5 MPa H2, a temperaturas entre 240 °C y 400 °C y tiempos de reacción de 0,5 h y 1 h. Los resultados mostraron que el residuo mineral industrial fue más activo que el material de referencia y que presentó alta actividad hacia la ruptura de los enlaces C-O en el dibenciléter, siendo estos los enlaces responsables del ensamble de asfaltenos y preasfaltenos en la estructura molecular del carbón. Adicionalmente, la conversión del carbón incrementó significativamente en presencia del residuo mineral sulfurado alcanzando un valor de 83,9 %, valor 1,8 veces mayor que para la reacción sin catalizador, evidenciando el potencial del residuo mineral para ser usado como catalizador en la hidroconversión del carbón, debido a su buena actividad y bajo costo.An industrial mineral waste produced in the aluminum sulphate industry was selected as a low cost catalyst precursor. This material has been active in dibenzylether hydroconversion, as a model compound of C-O linkages in coal. Besides, it was used in the hydroconversion of a colombian subbituminous coal. The mineral waste and a commercial iron oxide (as reference material) were sulfided in order to produce iron sulfide, pyrrhotite type (Fe1-xS), which is the active phase in hydroconversion reactions. The solids were characterized by X-ray fluorescence, X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Catalytic tests with the model compound and coal were carried out at 5 MPa of H2, temperatures between 240 °C and 400 °C and reaction times were 0.5 h or 1 h. The results showed a higher activity of the industrial mineral waste compared with the reference material in the dibenzylether C-O bond cleavage. These kind of bonds are responsible for asphalthenes and preasphalthenes assembly in the molecular coal structure. In addition, coal conversion in presence of catalysts was 83.9 %, this value was 1.8 times higher than conversion without catalyst. Results show the potential of the industrial mineral waste to be used as catalyst in the hydroconversion of coal due to its good activity and low cost

Utilización de un residuo mineral industrial como catalizador en la hidroconversión de dibenciléter y de un carbón subbituminoso colombiano

An industrial mineral waste produced in the aluminum sulphate industry was selected as a low cost catalyst precursor. This material has been active in dibenzylether hydroconversion, as a model compound of C-O linkages in coal. Besides, it was used in the hydroconversion of a colombian subbituminous coal. The mineral waste and a commercial iron oxide (as reference material) were sulfided in order to produce iron sulfide, pyrrhotite type (Fe1-xS), which is the active phase in hydroconversion reactions. The solids were characterized by X-ray fluorescence, X-ray diffraction, Raman spectroscopy and scanning electron microscopy. Catalytic tests with the model compound and coal were carried out at 5 MPa of H2, temperatures between 240 °C and 400 °C and reaction times were 0.5 h or 1 h. The results showed a higher activity of the industrial mineral waste compared with the reference material in the dibenzylether C-O bond cleavage. These kind of bonds are responsible for asphalthenes and preasphalthenes assembly in the molecular coal structure. In addition, coal conversion in presence of catalysts was 83.9 %, this value was 1.8 times higher than conversion without catalyst. Results show the potential of the industrial mineral waste to be used as catalyst in the hydroconversion of coal due to its good activity and low cost.Un residuo mineral industrial, proveniente de la producción de sulfato de aluminio, se utilizó como precursor para la preparación de un catalizador de bajo costo, activo en reacciones de hidroconversión de dibenciléter, como compuesto modelo de las uniones C-O en el carbón, y de un carbón subbtituminoso colombiano. El residuo mineral y un óxido de hierro comercial (material de referencia) se sometieron a un proceso de sulfuración con el propósito de generar un sulfuro de hierro tipo pirrotita (Fe1-xS), el cual es la fase activa del hierro en reacciones de hidroconversión. Los sólidos se caracterizaron por difracción de rayos X, fluorescencia de rayos X, espectroscopía Raman y microscopía electrónica de barrido. Las pruebas de actividad catalítica, con el compuesto modelo y el carbón, se realizaron a 5 MPa H2, a temperaturas entre 240 °C y 400 °C y tiempos de reacción de 0,5 h y 1 h. Los resultados mostraron que el residuo mineral industrial fue más activo que el material de referencia y que presentó alta actividad hacia la ruptura de los enlaces C-O en el dibenciléter, siendo estos los enlaces responsables del ensamble de asfaltenos y preasfaltenos en la estructura molecular del carbón. Adicionalmente, la conversión del carbón incrementó significativamente en presencia del residuo mineral sulfurado alcanzando un valor de 83,9 %, valor 1,8 veces mayor que para la reacción sin catalizador, evidenciando el potencial del residuo mineral para ser usado como catalizador en la hidroconversión del carbón, debido a su buena actividad y bajo costo

DOT tomography of the solar atmosphere. IV. Magnetic patches in internetwork areas

We use G-band and Ca II H image sequences from the Dutch Open Telescope (DOT) to study magnetic elements that appear as bright points in internetwork parts of the quiet solar photosphere and chromosphere. We find that many of these bright points appear recurrently with varying intensity and horizontal motion within longer-lived magnetic patches. We develop an algorithm for detection of the patches and find that all patches identified last much longer than the granulation. The patches outline cell patterns on mesogranular scales, indicating that magnetic flux tubes are advected by granular flows to mesogranular boundaries. Statistical analysis of the emergence and disappearance of the patches points to an average patch lifetime as long as 530+-50 min (about nine hours), which suggests that the magnetic elements constituting strong internetwork fields are not generated by a local turbulent dynamo.Comment: 8 pages, 6 figure

Interplay between PFBC-associated SLC20A2 and XPR1 phosphate transporters requires inositol polyphosphates for control of cellular phosphate homeostasis

Solute carrier family 20 member 2 (SLC20A2) and xenotropic and polytropic retrovirus receptor 1 (XPR1) are transporters with phosphate uptake and efflux functions, respectively. Both are associated with primary familial brain calcification (PFBC), a genetic disease characterized by cerebral calcium-phosphate deposition and associated with neuropsychiatric symptoms. The association of the two transporters in the same disease suggests that they jointly regulate phosphate fluxes and cellular homeostasis, but direct evidence is missing. Here, we found that cross-talk between SLC20A2 and XPR1 regulates phosphate homeostasis and identify XPR1 as a key inositol polyphosphate (IP)-dependent regulator of this process. We found that overexpression of wildtype SLC20A2 increases phosphate uptake as expected, but also unexpectedly increases phosphate efflux, whereas PFBC-associated SLC20A2 variants did not. Conversely, SLC20A2 depletion decreased phosphate uptake only slightly, most likely compensated for by the related SLC20A1 transporter, but strongly decreased XPR1-mediated phosphate efflux. The SLC20A2-XPR1 axis maintained constant intracellular phosphate and ATP levels, which both increased in XPR1-KO cells. Elevated ATP is a hallmark of altered inositol pyrophosphate (PP-IP) synthesis, and basal ATP levels were restored after phosphate efflux rescue with wildtype XPR1, but not with XPR1 harboring a mutated PP-IP-binding pocket. Accordingly, inositol hexakisphosphate kinase 1-2 (IP6K1-2) gene inactivation or IP6K inhibitor treatment abolished XPR1-mediated phosphate efflux regulation and homeostasis. Our findings unveil an SLC20A2-XPR1 interplay that depends on IPs such as PP-IPs and controls cellular phosphate homeostasis via the efflux route, and that alteration of this interplay likely contributes to PFBC