Aseguramiento de la calidad como oportunidad de mejora en los laboratorios de investigación

Since the end of the 19th century, when the first research laboratories were created in Colombia, and at the beginning of the 20th century, with the creation of the first scientific societies, a way of working in research began to develop that was replicated and extended for decades to different parts of the country. In this way of working, there was little collaboration with other centers, either due to communication problems, lack of cooperation in some areas, or simply for the protection of information.  Desde finales del siglo XIX, cuando se crearon los primeros laboratorios de investigación en Colombia, y a principios del siglo XX, con la creación de las primeras sociedades científicas, se empezó a gestar una forma de trabajo en investigación que se fue replicando y extendiendo durante décadas a diferentes lugares del país. En esta forma de trabajo existía una baja colaboración con otros centros, ya fuera por problemas de comunicación, falta de cooperación en algunas áreas o, simplemente, por protección de la información

Caracterización morfológica del SARS-CoV-2 mediante microscopía electrónica

This paper reviews the available literature on the morphological characterization of the SARS-CoV-2 virus by electron microscopy. It presents the most relevant technical aspects for the preparation of samples used by various authors in the field because the details related to said preparation are decisive to obtain the images. In addition, it addresses biosecurity-related factors. Finally, the main morphological characteristics of the virus are described based on the images found in the literature. The morphology of the virus is characterized by a crown-like shape on its surface. Such crowns are composed of spikes and other proteins, forming layers on the surface that are used to penetrate and bind to host cells through the cell membrane.En este trabajo se realizó una revisión sobre la caracterización morfológica del virus SARS-CoV-2 mediante microscopía electrónica. Se presenta una revisión sobre los aspectos técnicos más relevantes para la preparación de las muestras usadas por varios autores en la literatura. En los detalles finos de la preparación radica el éxito en la obtención de las imágenes. Además, se presentan los detalles relacionados con la bioseguridad. Finalmente, se realiza una descripción de las principales características morfológicas del virus a partir de las imágenes disponibles en la literatura. La morfología del virus se caracteriza por la forma tipo corona en su superficie. La corona está formada por espigas y otras proteínas que forman una capa en la superficie, la cuales se utilizan para unir y penetrar sus células huésped a través de la membrana celular

Preparación y caracterización de carbón activado a partir de torta de higuerilla

Biomass residues have been used to produce activated carbons. On this process, the activation method and the raw composition determine the properties as porosity and surface area of the charcoal. After the extraction of castor oil, there is a solid byproduct (cake) of low added value, which was used in the production of activated carbon to add value to this waste. For this purpose two traditional methods were used, first, physical activation using as activating agents steam, CO2 and mixture of both, and additionally chemical activation using K2CO3 as the activating agent. Some activated carbons were characterized using N2 adsorption isotherms, BET surface areas varied between 255.98 (m2/g) and 1218.43 (m2/g). By SEM and EDS analysis was possible to observe that materials obtained by the two types of activation are principally amorphous and morphological characteristics of the carbon obtained by physical activation are very different from those obtained by chemical activation. Finally, through impregnation of inorganic phases of Ni and Mo was revealed that the high dispersion characteristics, these carbonaceous materials will have potential to be used as catalyst support.Los residuos de biomasa han sido usados para la producción de carbones activados, en este proceso, el método para obtenerlos y la materia prima determinan propiedades como la porosidad y área superficial del carbón. Tras la extracción del aceite de higuerilla se genera un subproducto sólido (torta) de difícil salida, que fue usado en la producción de carbón activado, en busca de la valorización de este residuo sólido. Para tal fin se emplearon dos métodos tradicionales. En primer lugar, activación física usando como agentes activantes vapor de agua, CO2 y una mezcla de estos gases, adicionalmente se realizó activación química usando K2CO3 como agente activante. Algunos de los carbones obtenidos fueron caracterizados usando isotermas de adsorción/desorción de N2 donde se lograron áreas superficiales BET entre 255,98 (m2/g) y 1218,43 (m2/g), del análisis por SEM y EDS se encontró que los materiales obtenidos por ambos tipos de activación son principalmente amorfos y que las características morfológicas de los carbones obtenidos mediante activación física son muy diferentes de los obtenidos por activación química. Finalmente, a través de impregnación con sales de Ni y Mo se evidenció que por características como la alta dispersión obtenida, estos materiales carbonosos presentan un potencial para ser usados como soporte catalítico

Modification of ASTM B107 AZ31 alloy with TiO2 particles using the dip-coating method

Introduction− Magnesium alloys have been known for its bio-compatible characteristics and tissue restoration properties. On the other hand, TiO2 has been found to decrease the corrosion rates of the magnesium alloys.Objective−In this work, the dip-coating technique was used to coat the magnesium alloy with TiO2 particles in order to evalu-ate its corrosion resistance.Methodology−The particles were analyzed by Scanning Elec-tron Microscopy (SEM) and visual inspection. Additionally, hy-drogen evolution tests were performed to understand the effect of adding TiO2 in corrosion rates of Mg-alloys.Results− The results showed the positive effect of TiO2 in the improvement of the ASTM B107 AZ31B Mg alloys corro-sion by an indirect measurement through hydrogen evolution tests. The bare ASTM B107 AZ31B showed a corrosion 29 times faster compared to the coated alloy. The thickness of the coatings obtained using the dip-coating method is thin-ner than 20 nm. Conclusions−TiO2 particles were aggregated on the surface of the ASTM B107 AZ31B alloy with a controlled speed. SEM images have shown the improvement of the coating when the H2O concentration in the sol increased. Another important parameter is the withdrawal speed during the dip-coat process which was found to be better at a speed of 3mm/min. Hydrogen evolution in the acid solution showed that coated ASTM B107 AZ31B has less hydrogen production during the corrosion test. The dip-coating technique can also be used to coat polypropyl-ene discs entirely.Introducción− Las aleaciones de magnesio son conocidas por sus ca-racterísticas biocompatibles y propiedades de restauración de tejidos; por otro lado, se ha encontrado que el TiO2 disminuye las velocidades de corrosión de las aleaciones de magnesio.Objetivo− En este trabajo, la técnica de recubrimiento por inmersión se usó para recubrir una aleación de magnesio con partículas de TiO2 y evaluar su comportamiento a corrosión.Metodología− Las partículas se analizaron por microscopía electrónica de barrido (SEM) e inspección visual. Además, se realizaron pruebas de evolución de hidrógeno para comprender el efecto de la adición de TiO2en la velocidad de corrosión de la aleación de Mg.Resultados− Los resultados mostraron el efecto positivo de TiO2 en la mejora de la corrosión de aleaciones de ASTM B107 AZ31B Mg mediante una medición indirecta a través de pruebas de evolución de hidrógeno. La aleación ASTM B107 AZ31B sin recubrimiento muestra una corro-sión 29 veces más rápida en comparación con la aleación recubierta. El espesor obtenido mediante el método de recubrimiento por inmersión es inferior a 20 nm. Conclusiones− Las partículas de TiO2 se agregaron en la superficie de la aleación ASTM B107 AZ31B con una velocidad controlada. Las imáge-nes SEM mostraron la mejora del recubrimiento cuando aumenta la con-centración de H2O en el sol. Otro parámetro importante es la velocidad de extracción durante el proceso de recubrimiento por inmersión, que resultó ser mejor a una velocidad de 3 mm/min. La evolución del hidró-geno en la solución mostró que la aleación ASTM B107 AZ31B recubierta reportó menos producción de hidrógeno durante la prueba de corrosión. La técnica de recubrimiento por inmersión puede realizarse en polipro-pileno y, finalmente, obtener una superficie completamente recubierta

Evaluación de propiedades mecánicas de compuestos manufacturados a partir de contenedores de Tetra Pak® reciclados

Context: Tetra Pak® is a common material used for the production of food containers. Currently, those containers are recycled by physical separation of the cellulose fibers through a hydro pulped process, but sometimes separating the individual components is not economically viable. This work evaluates an al­ternative process to obtain composites from recycled Tetra Pak®. Methodology: Tetra Pak® used containers were co­llected and cut into small pieces at the laboratory. Then, the containers were hot-pressed to obtain sheets in a manual hydraulic press by using different confi­gurations. Samples were cut, and their tensile stren­gth was evaluated (ASTM D3039). Failure analysis of samples was carried out by FE-SEM to identify issues related to processing and to understand the differen­ces in mechanical properties. Results: The results showed that the lowest tensile strength was 9.5 MPa (type I sample) and the highest tensile strength was 37.4 MPa (type III sample). Conclusions: The results of mechanical tests show that this material can be used for non-structural purposes in the building industry. Failure analysis shows that fiber pull-out and delamination are the most impor­tant failure mechanisms in type I samples. For type III sample, failure was produced by a sequence of intralaminar fracturesContexto: Tetra Pak® es un material común que se uti­liza para recipientes de alimentos. Actualmente, esos contenedores se reciclan mediante la separación físi­ca de las fibras de celulosa a través de un proceso de hidropulpeado, pero a veces no es económicamente viable separar los componentes individuales. En este trabajo, se evaluó un proceso alternativo para obtener materiales compuestos de Tetra Pak® reciclado. Metodología: Inicialmente, los contenedores de Tetra Pak® usados se recolectaron y cortaron en trozos pe­queños en el laboratorio. Después, los contenedores se prensaron en caliente para obtener laminados en una prensa hidráulica manual utilizando diferentes configuraciones. Después de obtener los materiales compuestos, se cortaron las muestras y se evaluó su resistencia a la tracción (ASTM D3039). El análisis de fallas de las muestras fue realizado por FE-SEM para identificar problemas relacionados con el pro­cesamiento y para comprender las diferencias en las propiedades mecánicas. Resultados: Los resultados mostraron que la menor resistencia a la tracción era de 9,5 MPa (muestras de tipo I). La mayor resistencia a la tracción fue de 37,4 MPa para muestras de tipo III. Conclusiones: Los resultados de las pruebas mecá­nicas permitieron concluir que el material se puede utilizar para fines no estructurales en la industria de la construcción. El análisis de fallas mostró que el desprendimiento de la fibra es el mecanismo más im­portante en las muestras de tipo I. Para las muestras de tipo III, la fractura se produjo por una secuencia de fallas interlaminares

Bimetallic PtSn/C catalysts obtained via SOMC/M for glycerol steam reforming

A detailed study on the preparation of bimetallic PtSn/C catalysts using surfacecontrolled synthesis methods, and on their catalytic performance in the glycerol steam reforming reaction has been carried out. In order to obtain these well-defined bimetallic phases, techniques derived from Surface Organometallic Chemistry of Metals (SOMC/M) were used. The preparation process involved the reaction between an organometallic compound ((C4H9)4Sn) and a supported transition metal (Pt) in a H2 atmosphere. Catalysts with Sn/Pt atomic ratios of 0.2, 0.3, 0.5, and 0.7 were obtained, and characterized using several techniques: ICP, H2 chemisorption, TEM and XPS. These systems were tested in the glycerol steam reforming varying the reaction conditions (glycerol concentration and reaction temperature). The best performance was observed for the catalysts with the lowest tin contents (PtSn0.2/C and PtSn0.3/C). It was observed that the presence of tin increased the catalysts’ stability when working under more severe reaction conditions.Centro de Investigación y Desarrollo en Ciencias Aplicada

Green synthesis of polypyrrole-supported metal catalysts: application to nitrate removal in water

Pt and Pt/Sn catalysts supported on polypyrrole (PPy) have been prepared using Ar plasma to reduce the metal precursors dispersed on the polymer. The PPy support was synthesized by chemical polymerization of pyrrole with FeCl3·6H2O, this leading to the conducting form of the polymer (conductimetric measurements). The Ar plasma treatment produced a partial reduction of platinum ions, anchored as platinum chloro-complexes to the PPy chain, into metallic platinum. A homogeneous distribution of Pt and Sn nanoparticles was observed by TEM. Activity of the PPy-supported catalysts was evaluated in the reduction of aqueous nitrate with H2 at room temperature. Nitrate concentration in water below the maximum acceptable level of 50 mg L−1 was achieved with all catalysts. However, considering not only efficiency in nitrate reduction, but also minimized concentrations of undesired nitrite and ammonium, the monometallic Pt catalyst seems to be the most promising one.Financial support from Generalitat Valenciana, Spain (PROMETEO/2009/002 – FEDER and PROMETEOII/2014/004) is gratefully acknowledged. Support by PEst-C/EQB/LA0020/2013, financed by FEDER through COMPETE – Programa Operacional Factores de Competitividade, and by FCT – Fundação para a Ciência e a Tecnologia; NORTE-07-0162-FEDER-000050, financed by QREN, ON2 and FEDER is acknowledged by LCM group. O. S. G. P. Soares acknowledges the grant received from FCT (SFRH/BPD/97689/2013)

Characterization of airborne particulate matter and its toxic and proarrhythmic effects: A case study in Aburrá Valley, Colombia

Particle matter (PM) is a complex mixture of particles suspended in the air, mainly caused by fuel combustion from vehicles and industry, and has been related to pulmonary and cardiovascular diseases. The Metropolitan Area of Aburrá Valley in Colombia is the second most populous urban agglomeration in the country and the third densest in the world, composed of ten municipalities. Examining the physicochemical properties of PM is crucial in comprehending its composition and its effects on human health, as it varies based on the socioeconomic dynamics specific to each city. This study characterized the PM collected from the north, south, and central zones to evaluate its chemical composition and morphology. Different elements such as silicon, carbon, aluminum, potassium, calcium, sodium, iron, magnesium, and copper and the presence of unburned fuel, motor oil, and silicon fibers were identified. In vitro and in silico studies were conducted to evaluate the toxicity of the PM, and it was found that the PM collected from the central zone had the greatest impact on cell viability and caused DNA damage. The in silico study demonstrated that PM has concentration-dependent proarrhythmic effects, reflected in an action potential duration shortening and an increased number of reentries, which may contribute to the development of cardiac arrhythmias. Overall, the results suggest that the size and chemical composition of ambient PM can induce toxicity and play an important role in the generation of arrhythmiasThis work was supported by the Ministerio de Ciencia Tecnología e Innovación (MINCIENCIAS) from Colombia, through grant No. 120677757994 and by the Dirección General de Política Científica de la Generalitat Valenciana PROMETEO/2020/043. The work of Palacio was supported by the “Programa de excelencia doctoral del Bicentenario 2019” of MINCIENCIAS. The work of Durango-Giraldo and Zapata-Hernandez was supported by the “Convocatoria para el fortalecimiento de proyectos en ejecución de CTeI en ciencias de la salud con talento joven e impacto regional” of MINCIENCIASPostprint (published version

Atrial proarrhythmic effect of lead as one of the PM10 metal components of air pollution. An in-silico study

[EN] Particulate matter (PM) is considered the most severe environmental pollution problem due to its serious effects on human health associated with an increased risk of cardiovascular morbidity and mortality. In this work, a physicochemical characterization of PM10 from the city of Medellin was developed. The results evince that lead (Pb) is one of the most abundant elements since it is present in all analyzed samples. Therefore, Pb was chosen to perform an in-silico study to assess its effects on atrial arrhythmias generation. For this purpose, we developed a model representing the Pb2+ blocking effect on the L-type calcium channel. This formulation was incorporated in a human atrial cell mathematical model and in 2D and 3D models of human atria. The simulations showed a proarrhythmic effect at high Pb2+ concentrations, through shortening of action potential duration inducing the generation of reentrant activity and atrial flutter. The results contribute to the knowledge about the cardiac physiopathological processes, triggered by lead as one of the main PM10 metal components of air pollution, that yields the generation of arrhythmias.This work was supported by Ministerio de Ciencia, Tecnologi a e Innovacion MINCIENCIAS from Colombia, through grant No. 120677757994; and by the Direccion General de Politica Cientifica de la Generalitat Valenciana PROMETEO/2020/043.Palacio, LC.; Pachajoa, DC.; Durango-Giraldo, G.; Zapata-Hernández, C.; Ugarte, JP.; Saiz Rodríguez, FJ.; Buitrago-Sierra, R.... (2021). Atrial proarrhythmic effect of lead as one of the PM10 metal components of air pollution. An in-silico study. PLoS ONE. 16(10):1-17. https://doi.org/10.1371/journal.pone.0258313S117161