1,720,966 research outputs found
Catalytic effect of boric acid in CO2 absorption
No full textAs a consequence of the accelerated industrial growth, the problem involved in the treatment of gases emitted into the atmosphere by the industrial sector, especially carbon dioxide, takes on greater relevance. Therefore, the development and exploration of new technologies for the capture of CO2 must always be under investigation. This study employed a pilot-scale absorption unit to investigate the capacity of the absorption of carbon dioxide using an aqueous solution of sodium hydroxide and boric acid as catalyst. The evaluated parameters included two different concentrations of absorbent, operating temperature, and the kinetic effect due to the presence of boric acid. The results showed that when the concentration of the absorbent was increased, the removal of CO2 is highly favored. Also, the kinetic effect was favored when the operating temperature was stepped up, and the presence of boric acid improves the CO2 kinetic rate.Como consecuencia del acelerado crecimiento industrial, el problema relacionado con el tratamiento de los gases emitidos a la atmósfera por el sector industrial, especialmente el dióxido de carbono, adquiere una mayor relevancia. Por lo tanto, el desarrollo y la exploración de nuevas tecnologías para la captura de CO₂ deben estar siempre bajo investigación. Este estudio empleó una unidad de absorción a escala piloto para investigar la capacidad de absorción de dióxido de carbono utilizando una solución acuosa de hidróxido de sodio y ácido bórico como catalizador. Los parámetros evaluados incluyeron dos diferentes concentraciones del absorbente, la temperatura de operación y el efecto cinético debido a la presencia de ácido bórico. Los resultados mostraron que, cuando se incrementó la concentración del absorbente, la eliminación de CO₂ se vio altamente favorecida. Asimismo, el efecto cinético fue favorecido cuando se aumentó la temperatura de operación, y la presencia de ácido bórico mejora la velocidad cinética del CO₂.PregradoINGENIERO(A) EN QUIMIC
Acidogenic fermentation for the production of volatile fatty acids from cassava sour starch extraction process wastewater
No full textCassava and its processed products, such as sour starch, form the economic backbone of various communities in Colombia. However, their production generates effluents with high organic loads, cyanide concentrations, and acidic pH levels, leading to significant deterioration of receiving wáter sources. If these discharges are not properly treated beforehand, bodies of water may become unsuitable for human consumption, fishing, or recreation. Previous research indicates that this type of wastewater can be treated through anaerobic digestion, yielding methane as the primary product. However, studies also suggest that the volatile fatty acids produced during the acidogenic phase of anaerobic digestion, known as acidogenic fermentation, have valuable applications in various chemical and biological processes. This doctoral thesis begins with an introduction to the environmental issues caused by effluents from sour starch extraction from cassava, along with an analysis of previous research and emerging trends in its treatment. It also outlines the challenges that motivated this study and led to the establishment of three specific objectives (Chapter 1). Next, acidogenic fermentation and volatile fatty acid production are examined as alternatives for wastewater treatment through a bibliometric análisis of existing scientific literature (Chapter 2). This analysis identified key operational variables, which were evaluated at the laboratory scale for the substrate of interest. The individual and interactive effects of fermentation time and pH (Chapter 3), as well as the substrate-microorganism relationship and temperature (Chapter 4), were examined. Additionally, recognizing the importance of modeling in complementing experimental trials and enhancing the understanding of biological processes, a kinetic study was conducted on the acidogenic fermentation of wastewater from cassava processing. This study identified the models that best fit soluble organic matter consumption and volatile fatty acid production (Chapter 5). Finally, this thesis synthesizes the results and outlines perspectives for future research in the field (Chapter 6).La yuca y los productos derivados de su procesamiento, como el almidón agrio, se han convertido en la base de la economía de diversas poblaciones en Colombia. Sin embargo, su producción genera efluentes potencialmente contaminantes debido a la elevada carga orgánica, las concentraciones de cianuro y el pH ácido, lo que provoca un deterioro significativo de las fuentes hídricas receptoras. Si estos vertimientos no reciben un tratamiento previo, los cuerpos de agua pueden quedar inhabilitados para otros usos, como el consumo humano, la pesca o la recreación. Investigaciones previas han demostrado que este tipo de agua residual puede tratarse mediante digestión anaerobia, obteniéndose metano como principal producto. No obstante, otros estudios han evidenciado que los ácidos grasos volátiles generados en la fase acidogénica de la digestión anaerobia, conocida como fermentación acidogénica, pueden tener aplicaciones valiosas en diversos procesos químicos y biológicos. Esta tesis doctoral inicia con una introducción a la problemática ambiental generada por los efluentes de la extracción de almidón agrio a partir de la yuca, así como un análisis de antecedentes y nuevas tendencias en su tratamiento. Además, se presentan los desafíos que justificaron el desarrollo de este trabajo y permitieron el planteamiento de tres objetivos específicos (Capítulo 1). Posteriormente, se explora la fermentación acidogénica y la producción de ácidos grasos volátiles como alternativa para el tratamiento del agua residual, a través de un análisis bibliométrico de la literatura científica existente (Capítulo 2). Como resultado de este análisis, se identificaron variables operacionales clave del proceso, las cuales fueron evaluadas a escala de laboratorio para el sustrato de interés. En este contexto, se analizaron los efectos individuales e interactivos del tiempo de fermentación y el pH (Capítulo 3), así como la relación sustrato-microorganismo y la temperatura (Capítulo 4). Adicionalmente, considerando la importancia de la modelación para complementar los ensayos experimentales y mejorar la comprensión de los procesos biológicos, se realizó un estudio cinético de la fermentación acidogénica del agua residual generada en el procesamiento de la yuca. En este estudio, se identificaron los modelos que mejor se ajustan al consumo de materia orgánica soluble y a la producción de ácidos grasos volátiles (Capítulo 5). Finalmente, esta tesis presenta una síntesis de los resultados obtenidos y plantea algunas perspectivas para futuras investigaciones en este campo (Capítulo 6).DoctoradoDOCTOR(A) EN INGENIERÍA - ÉNFASIS INGENIERÍA SANITARIA Y AMBIENTA
Conceptos básicos de análisis de fluxes metabólicos
No full textMetabolism represents the biological level that is most related to the phenotypes of the cell and, alterations or reprogramming of this can (i) affect the production of primary or secondary metabolites in microorganisms of biotechnological interest, (ii) favor or not the inhibition of growth in pathogenic organisms and (iii) developing metabolic disorders such as obesity or diabetes, among others. The study of metabolism, redesign, and redirection of metabolic fluxes has become an important area of research (also known as Metabolic Engineering), as it has allowed the development and design of improved biological processes, the identification of therapeutic targets, the design of therapeutic strategies to cure metabolic disorders and the identification of biomarkers in cancer, among others. Currently, the development of computational methodologies is allowing to study the cell metabolism under different environmental conditions and directing experiments with the model's predictions. The purpose of this review is to highlight the importance of metabolic flux analysis as a general methodology to study metabolic reprogramming in different organisms of biotechnological, medical, and therapeutic interest. This work condenses the theoretical bases and key concepts to understand the analysis of metabolic fluxes, which will be a fundamental input for those who are entering to the world of systems biology or related areas.El metabolismo representa el nivel biológico que más se relaciona con los fenotipos de la célula y, las alteraciones o reprogramaciones de éste pueden, entre otras, (i) afectar la producción de metabolitos primarios o secundarios en microorganismos de interés biotecnológico, (ii) favorecer o no la inhibición del crecimiento en organismos patógenos y (iii) desarrollar desórdenes metabólicos como la obesidad o la diabetes. Es por ello, que el estudio del metabolismo, el rediseño, y el redireccionamiento de fluxes metabólicos se ha convertido en un área importante de investigación (también conocida como Ingeniería Metabólica), ya que ha permitido el desarrollo y diseño de procesos biológicos mejorados, la identificación de blancos terapéuticos, el diseño de estrategias terapéuticas para curar desordenes metabólicos y la identificación de biomarcadores en cáncer, entre otros. Actualmente, se han desarrollado metodologías computacionales que permiten estudiar el metabolismo celular a diferentes condiciones medioambientales, dirigiendo la experimentación con las predicciones del modelo. El propósito de esta revisión es resaltar la importancia del análisis de fluxes metabólicos como una metodología general para estudiar la reprogramación metabólica en distintos organismos de interés biotecnológico, médico, y terapéutico. Este trabajo condensa las bases teóricas y los conceptos claves para entender el análisis de fluxes metabólicos, lo cual será un insumo fundamental para aquellos que se están adentrando al mundo de la biología de sistemas o áreas afines
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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