bluuebunny/crossref_metadata_2025 huggingface dataset:
Catálisis en Colombia: estado actual y oportunidades para el futuro
Authors: Henao.L Juan D. , Montes de Correa Consuelo
Published: July 2024

En este artículo se hace una revisión del estado actual de la catálisis en Colom­bia. Se empieza con una reseña sobre las tendencias mundiales en aspectos relacionados con la química y el medio ambiente, mostrando cómo dichas tendencias han influido en la investigación sobre Catálisis que se realiza en Colombia. Luego se plantean algunos retos que surgen de las necesidades de la industria nacional resaltando una serie de oportunidades, previamente iden­tificadas, para el desarrollo de tecnologías catalíticas con base en la gran can­tidad de recursos naturales disponibles en nuestro país.
Síntesis y caracterización de los catalizadores Fe-ZeO2 y Cu-ZrO2
Authors: Castro Liliana Patricia , Montes de Correa Consuelo
Published: July 2024

Se comparan algunas características fisicoquímicas de los xerogeles que con­tienen Cu o Fe soportados en circonia. Se usaron ácido sulfúrico o hidróxido de amonio como catalizadores de hidrólisis durante la etapa de gelación. Los materiales sulfatados cristalizaron principalmente en la fase tetragonal, exhi­bieron mayor área superficial y presentaron mayor número de sitios ácidos que los catalizadores preparados en medio básico. La adición de los precurso­res de hierro y cobre en el gel de síntesis durante la preparación de la circonia sulfatada, condujo a una mayor estabilización de las especies sulfato en dicho soporte, especialmente bajo condiciones oxidantes.
Posibilidades de innovación en la industrial de procesos químicos en Colombia
Authors: Tapias-García Heberto , Monsalve-Meléndez Xiomara , Quintero-Posada Álvaro
Published: July 2024

El artículo señala posibilidades de innovación en materias primas, procesos, productos, unidades de transformación (operaciones unitarias y reactores), así como en prácticas de organización, gestión y de relaciones en la industria de procesos químicos en Colombia. El universo de oportunidades sugerido nace del análisis de tendencias, retos y problemas identificados de la evolu­ción histórica de este sector industrial en los ámbitos mundial y local, y de la necesidad de superar el proceso de desindustrialización del país corno resulta­do de la apertura y globalización de la economía.
Síntesis y caracterización de un nuevo material tipo fosfato de cobre
Authors: Sierra Germán , Echavarría Adriana , Palacio Luz Amparo , Saldarriaga Carlos
Published: July 2024

Un nuevo fosfato de cobre, con fórmula CuPO4H.0,5H2O, fue sintetizado usando el método hidrotérmico a bajas temperaturas y caracterizado mediante difracción de rayos X de polvos, análisis termogravimétrico y análisis químico. El patrón de rayos X se indizó dando como resultado una celda monoclínica con grupo espacial P21/c y parámetros de celda: a= 10,6524(2), b = 8,4730(2), c = 9, 2204(2) A, β= 92,43(0)  ͦy posee un volumen de 831,47 A3.El análisis termogravimétrico muestra pérdida de peso total del 25,5% entre 70 y 580  ͦC. Un estudio de estabilidad térmica mostró que el sólido no es estable por encima de los 200  ͦC y provoca cambios estructurales significativos.
Descripción de varios métodos y aplicaciones de la radiolocalización a servicios para usuarios móviles
Authors: Flórez-Serna Luis Alberto , Obando-Cadavid Sergio Román
Published: July 2024

La tecnología inalámbrica ha abierto un nuevo mundo, dando a los usuarios móviles la libertad para tener conocimiento y comunicarse a voluntad con otros usuarios. Las nuevas plataformas de tecnología han evolucionado para unir a los usuarios en una gran comunidad móvil que comparte amistad, infor­mación e intereses comunes. Esta tendencia en la evolución esta ligada al aumento del uso móvil y son excelentes noticias para los operadores móviles quienes prevén hacer los servicios basados en la posición su prioridad. La tecnología geoespacial ha sumado una nueva dimensión a la experiencia móvil y el advenimiento de los servicios basados en la posición ha extendido estas libertades. Los sistemas basados en la posición serán la piedra angular de la Internet móvil, y el tiempo y el lugar serán valores añadidos a la infomtación pedida. Este documento contiene información necesaria para comprender el funcio­namiento de los nuevos servicios que se ven venir con las mejoras en implementación que se están haciendo en las redes celulares del mundo, ade­más posee una descripción de que son los servicios basados en la radiolocalización, un poco de historia, cómo funcionan, de qué se sirven para operar, sus principales características y una mirada hacia el futuro de qué nuevos servicios se pueden sumar a los ya existentes.
Sistemas CAD basados en el conocimiento
Authors: Bello-Pérez Rafael
Published: July 2024

En este artículo se presenta un análisis del diseño asistido por computadoras (Computer-Aided Design, CAD) que incluye los beneficios del empleo de la computación en el diseño y los modelos del proceso de diseño para sistemas CAD. Luego se analiza la conveniencia de introducir las técnicas de inteligen­cia artificial al desarrollar un sistema CAD y se relacionan métodos de solución de problemas de la lA aplicables en el desarrollo de sistemas CAD basados en el conocimiento.
Retos en la aplicabilidad de la norma colombiana sobre el control de dioxinas y furanos en incineradores
Authors: Aristizabal-Zuluaga Beatriz , González-García Jairo , Montes de Correa Consuelo
Published: July 2024

Los incineradores de desechos hospitalarios, municipales y hornos crematorios se han identificado como los principales generadores de dioxinas y furanos. Colombia no ha sido ajena a esta problemática. Recientemente, el Ministerio del Medio Ambiente estableció las pautas para regular las emisiones de incineradores de residuos sólidos y líquidos. La forma más directa de conocer el estado actual y la eficiencia de los sistemas de control que se implementen para cumplir con las normas es mediante el análisis de estas sustancias. Los análisis de dioxinas y furanos en muestras de cenizas de un incinerador de residuos hospitalarios de la ciudad de Medellín ilustran la metodología analítica establecida por organismos internacionales para la detección y cuantificación de dioxinas y furanos. Dado que los costos implicados en dichos análisis son demasiado altos, se requieren estrategias que faciliten el cumplimiento de la norma.
Destilería diversificada de alcohol
Authors: Rodriguez-R. Pedro A. , Lombardi Gerardo , Corsini Romeu , Pérez-Ones Osney
Published: July 2024

Se presenta el proceso tecnológico y la evaluación de la factibilidad económi­ca y emergética de una destilería diversificada de alcohol (DDA) proyectada para operar como agroindustria. El proyecto está concebido bajo la concep­ción de máxima eficiencia termodinámica y productiva, calidad ambiental y social, con lo que se da respuesta a los conceptos de desarrollo sostenible y producción más limpia. Se emplean el control biológico de plagas y procesos regenerativos y reciclables, ton significativos resultados económicos y ecológicos. El proyecto tiene en cuenta las normas internacionales de preser­vación ambiental, pues destina el 20% de sus áreas para este fin.
Incremento de productividad por recuperación de calor en gases de chimenea de un horno de cubilote
Authors: Mejía Hector Daniel , Silva Claudia , Aristizábal Ricardo
Published: July 2024

Sobre la base de la primera ley de la termodinámica se realiza el balance de calor para dos cubilotes típicos y para el cubilote de la Universidad de Antioquia, en este último, antes y después de ser instalado y puesto a punto el sistema de recuperación de calor, que opera con dos regeneradores de lecho empacado. Con los resultados obtenidos en el prototipo eco-eficiente se demuestran las ventajas de trabajar un cubilote con sistemas que recuperen calor de los gases de chimenea, resaltando en este caso, el incremento en la productividad (52,4%) y en la temperatura del metal de salida (7,3%), además del cumplimiento de las normas ambientales vigentes en Colombia. Se destaca la necesidad de recupe­rar el calor de los gases de salida en todos los equipos donde se usan sistemas de combustión.
La ingeniería de materiales de la Universidad de Antioquia y la competitividad de las empresas
Authors: Valencia-Giraldo Asdrúbal
Published: July 2024

Se parte de las definiciones básicas de lo que es un material, sus diversos tipos, sus propiedades -químicas, físicas, mecánicas y dimensionales-y sus posibilidades en tecnología e ingeniería. Se informa sobre lo que es la ingeniería de materiales y el quehacer de estos ingenieros. Se explica la impor­tancia de las ingenierías de materiales y metalúrgica en la competitividad de las empresas y se ilustra con el papel que han desempeñado las de la Universidad de Antioquia.
Protección de materiales estructurales mediante pinturas intumescentes: una lucha desigual contral el fuego
Authors: Castaño Juan , Chico Belén , De la Fuente Daniel , Morcillo Manuel
Published: July 2024

Los incendios constituyen un problema de gran magnitud para las sociedades y sus sectores productivos, pues ocasionan grandes pérdidas humanas, mate­riales directas e indirectas, de dificil evaluación. Una manera de afrontar este fenómeno, desde el punto de vista ingenieril, tiene que ver con la prevención. En este sentido, las pinturas intumescentes constituyen un desarrollo impor­tante y en continua evolución. Estas pinturas tienen la capacidad de proteger contra el fuego diversos mate­riales estructurales, entre los cuales se destaca el acero. Al contacto con el fuego, tienen la capacidad de hincharse hasta un espesor doscientas veces mayor que el original, formando una capa esponjosa que aísla térmicamente el acero. Esto puede significar un retraso en su colapso estructural, lo que puede implicar reducción en la siniestralidad del incendio. En este trabajo se presen­tan las principales características de este tipo de pinturas y se describen los lineamientos generales de un proyecto europeo que se lleva a cabo en la actua­lidad para evaluar su degradación en diferentes atmósferas y la influencia de la misma en sus propiedades de intumescencia.
Óptimo económico de máquinas y equipos Parte II. El modelo matemático
Authors: Poveda-Ramos Gabriel
Published: July 2024

Este artículo presenta un estudio desde el punto de vista matemático (algebraico y del análisis) de cierta clase de problema de la economía y la tecnología industrial, que se refieren a la compra o construcción, y operación de máqui­nas e instalaciones (bienes de capital, en general), que exigen una inversión financiera inicial, que se van a operar por algunos meses o aflos, en forma continuada, y que luego, finalmente, van a ser retirados para revenderlos como bienes usados o para desecharlos como materiales sin valor. Uno de los asun­tos clave en la ingeniería industrial es determinar desde el principio, con algu­na certidumbre, cuánto tiempo se va a mantener la máquina o instalación en uso. Esta determinación es necesaria para adoptar de manera racional y ópti­ma varias decisiones importantes, como por ejemplo: a qué oficios se le asig­na, qué productos o servicios va a entregar, qué régimen de mantenimiento se le va a aplicar, cómo se va a depreciar y otras diversas que son importantes y muy relevantes en la de empresa industrial. Entre otras novedades estamos introduciendo la noción de "dimensión física" de magnitudes financieras y económicas.
Hidrodecloración catalítica de diclorometano sobre Pd o Ni soportados en r-alúmina sol-gel
Authors: Aristizábal Beatriz , Martínez Leidy Marcela , Montes de Correa Consuelo
Published: July 2024

Se sintetizaron varios catalizadores cargados con paladio o níquel, soportados en y-alúmina preparada por el método sol-gel y se caracterizaron por difracción de rayos X, análisis elemental, adsorción de nitrógeno, TPR y TGA. Los catalizadores resultantes se evaluaron en la hidrodecloración catalítica de diclorometano al estudiar el efecto de varios parámetros: método de síntesis, condiciones de pretratamiento, temperatura de reacción, relación hidrógeno/organoclorado y tiempo de saturación. Bajo las condiciones estudiadas, los catalizadores impregnados exhibieron mayor actividad que los cogelados y la calcinación en flujo de He favoreció la actividad en comparación con la calci­nación en condiciones estáticas. La actividad de los catalizadores aumentó con la temperatura y con la relación H2/CH2Cl2. El tiempo en que el catalizador se dejó en contacto con la mezcla reactiva antes de iniciar la reacción (tiempo de saturación) influyó significativamente en su actividad. En general, se observó disminución de la actividad catalítica con el tiempo de saturación. Aunque el soporte y-alúmina sol-gel también fue activo para la reacción, indudablemente el Pd y Ni promueven la hidrodecloración.
Producción de frío a partir de campor magnéticos. Parte I: Conceptos básicos
Authors: Velásquez Juan Esteban , Chejne Farid , Hill Alan
Published: July 2024

El empleo de campos magnéticos para la generación de frío se está abriendo paso como una alternativa muy eficiente dentro de las técnicas de refrigera­ción. Esta tecnología se fundamenta en el cambio de entropía que experimen­tan algunos materiales magnéticos o superconductores cuando se someten a campos magnéticos fuertes. El trabajo se presenta en dos partes: en la prime­ra, se describe el fenómeno magnetocalórico, se compara el ciclo de refrige­ración convencional con el ciclo de refrigeración magnética, se presentan las ventajas y desventajas de esta técnica y por último, se describen las aplica­ciones más relevantes. En la segunda parte se presentará un análisis ter­modinámico de un refrigerador magnético.
Modelación de la renovación de la carga en motores cuatro tiempos. Una revisión
Authors: Agudelo John Ramiro , Sánchez Carlos , Valencia Alejandro
Published: July 2024

Este articulo presenta una revisión bibliográfica sobre las modelaciones mate­máticas para el proceso de renovación de la carga en motores de combustión interna alternativos (MCIA) de cuatro tiempos, el cual se constituye en una herramienta básica para lograr minimizar el trabajo que el motor realiza sobre los flujos entrante y saliente, ya que los elementos fisicos propios de la admi­sión y del escape son los responsables de la eficiencia del proceso y, con ello, de la potencia obtenible. La renovación de la carga se aborda por medio de modelos de flujo de aire, los cuales se clasifican, en su orden de complejidad y precisión, en cuasiestacionarios, de llenado y vaciado, y de acción de ondas (MAO). En la actualidad el interés se centra en los fenómenos transitorios y tridimensionales, aunque en la literatura predomina el análisis estable de preferencia unidimensional. De esta manera puede conocerse acertadamente la influencia de cada uno de los elementos fisicos que componen el sistema de renovación de la carga. Las técnicas de diferencias finitas son las más usadas para solucionar los sistemas de ecuaciones resultantes. Lo anterior está soportado en una sólida herramienta computacional que permite, cada vez más, que los ingenieros no tengan que ocuparse del manejo matemático y convergencia de los modelos, lo cual hasta hace unos años fue incluso abordado gráficamente.
Física e industria en Colombia
Authors: Poveda-Ramos Gabriel
Published: July 2024

Este artículo indica numerosos temas que son de importancia e interés en las industrias colombianas y cuyo tratamiento requiere conocimientos que son propios de los físicos. Por tanto propende a que en la preparación universita­ria de estos profesionales se les den conocimientos y experiencias adecuados para actuar eficazmente en muchas áreas industriales donde pueden llegar a ser muy útiles; y a que los empresarios industriales entiendan la importancia de la ciencia fisica avanzada en la vida de sus empresas.
Evaluation of total suspended particles (TSP) and respirable particles (PM10) in the zone of Guayabal, Medellín, Colombia, 2000
Authors: Gómez Alfredo , Henao Enrique , Molina Eliana , Molina Francisco
Published: July 2024

In this work total suspended particles (TSP) and breathable particles matter (PM10) were determined, in Guayabal sector-Medellín (Colombia), over 5 months in the year 2000.
The TSP daily average concentration was 113 µg/m3 , being lower than the daily norm value for Colombia (400 µg/m3). Nevertheless, the concentrations tended to be higher than annual norm of 100 µg/m3 . The PM10 daily concentrations, with an average of 74 µg/m3, were never higher than daily norm of 150 µg/m3, established by the Environmental Protection Agency of the United States (US EPA). But they tend to be higher than annual norm (50 µ/m3).
It was possible to obtain 101 TSP and PM10 data couples daily, which permitted to make a correlation little explored in Colombia, with results of R2 = 0,91. This permits an important economy in future studies, because, by measuring TSP it is possible to estimate with high reliability the PM10 value. The PM10/ TSP ratio showed an average of 0,62, indicating an important participation of Breathable Particles Matter with respect to Total Suspended Particles.
Biosorption of Fe, Al and Mn of acid drainage from coal mine using brown seaweed sargassum sp. in continuous process
Authors: Díaz Andrea , Arias John , Gelves Genaro , Maldonado Alfonso , Laverde Dionisio , Pedraza Julio , Escalante Humberto
Published: July 2024

The acid mine drainage (AMD) are leaches as result of a coal minning running, it have low pH and high concentrations of heavy metals that convert them in strong polluter; with the purpose of reduce its concentration, a continuous biosorption system was designed by removing heavy metals from drainages using a cheap biosorbent material. The brown seaweed was pre-treatment with solutions 0,1 N of NaOH, Ca(OH)2, NaCl, CaCl2, Na2SO4 y H2SO4 for to study the effect on biosorption process; the removal percentage were determined, which are better than 80% with the exception of pre-treatment with H2SO4 who cancel the algae sorption capacity. The seaweed was packed in plastic mesh and polyester tulle in the shape of a rectangular prism; there isn’t effect on the biosorption process by using this packets. The continuous biosorption process was studied in two units of operation: a packed-bed flow-through sorption column and an horizontal vessel like a canal with baffles, which treated adequately 3,5 and 4,7 l of AMD respectively, using in each one of them 100 g of algae. The burning of algae was studied like an alternative for the problem of handling of residual algae. The ashes kept the metals removed from AMD, furthermore keep stable too by the attack of solutions of different pH.
Solvent and ligand effects on α-pinene epoxidation with Methyltrioxorhenium/hydrogen peroxide system (MTO/H2 O2 )
Authors: Gonazález R. Lina María , Villa de P. Aída Luz , Gelbard Georges , Montes de Correa Consuelo
Published: July 2024

Several ligands were studied as co-catalysts for α-pinene epoxidation with MTO/H2O2. Pyridine is an efficient co-catalyst with dichlorometane, tetrahydrofuran or ethyl acetate. However, large amounts of pyridine are required. In contrast, with relatively small amounts of the Aromox surfactant, high activity and selectivity to α-pinene epoxide are obtained. The latter system has the additional advantage of requiring no chlorinated solvents which are environmentally less friendly.
Modelling of the coating process on surgical instrumentation with hard chromiun
Authors: Ruiz Jairo , Parra Carlos Mario , Bustamante Carlos Mario , Vélez Elkin , Rivera Luis Alfonso
Published: July 2024

This paper presents a statistical model useful in discribing the behavior of stainless steel surgical needle holders, with a hard cromium coating, in relation to time of exposure, flow density and tempeture variables. It is adjusted by a second order rotational compound experimental design. The proposed model accounts for 75% of the total of the observed responses and due to the complexity of the process involved, it is considered as very satisfactory.
Influence of the activation growth methods and electric potential sweep rate on the morphology and electrical properties of polyaniline films
Authors: Alzate Restrepo Vanesa , Vasco Calle Diego Andrés , González Ocampo Javier
Published: July 2024

The effect of the potential sweep rate and some growth activation methods on the morphology and conductivity of electropolymerized polyaniline was evaluated; these properties were studied via scanning electron microscopy (SEM) and faradaic impedance. At potential sweep rates higher than150 mV/s the films suffered important changes on their growth voltamograms and on their morphological properties. As concerns the growth activation methods, it was found that the potentiostatic step and broader potential scans form open morphology films, while those activated with a slower scan showed a compact morphology. It was found a close relationship between morphology, capacitance and conductivity. Also, films with branched structure showed higher conductivity and capacitance.
Welding repairing of cracks in cast iron covers
Authors: Ramos Morales Félix , Díaz Cedré Eduardo Manuel , Pozo Morejón Juan Alberto , Velásquez Pérez Enrique , Maza Sánchez Alexis Aurelio , García Manresa Ómar , Duffus Scott Alejandro
Published: July 2024

The welding repair technology of a cast iron cover of a drying cylinder from a paper mill is presented. The results of the base metal characterization are shown; possible reasons that originated the appearance of cracks in previous reparation are discussed; the undertaken decisions are explained in order to guide the process of a cover repair.
Magnetic refrigeration: analysis located electron model
Authors: Hoyos Quintero John Jairo , Velásquez Juan Esteban , Chejne Janna Farid , Hill Betancourt Alan Francis
Published: July 2024

Magnetic refrigeration is a technology with great commercial potential. Energy consumption and environmental impact associated with this technology are lower than those from conventional refrigeration systems. This paper presents the main aspects of the theory of the magnetocaloric effect. In addition, the application of the located electron model to magnetic refrigeration is analyzed. The model permits just a qualitative description of the behaviour of magnetocaloric effect in the vicinity of the magnetic transformation temperature.
Timing logic analyzer implemented in reprogrammable digital architecture
Authors: Duque Pérez Eugenio Antonio , Aedo Cobo José Édinson , Correa Julián , Ramírez Orozco Alexis Alberto , Nieto Londoño Rubén Darío , Torres Camilo , Bernal Noreña Álvaro
Published: July 2024

The conception, design, simulation, and implementation of a timing logic analyzer implemented on a reprogrammable digital architecture are described in this paper. The system was specified in VHDL [1] and implemented in a platform based on a FPGA (Field Programmable Gate Array) Spartan II. This methodology for analyzer implementation, allows obtaining a flexible, economic an efficient system in regards to processing capacity, since its modular characteristics make possible, through the use several of the developed subsystems, to scale the system when necessary.
Computational modelling and simulation using geographical information systems (GIS) with system dynamics applied to epidemiological phenomena
Authors: Castro Castro Carlos Arturo , Londoño Ciro Libardo Antonio , Valdés Quintero Juan Carlos
Published: July 2024

In this paper, advances of the research project “Computational modelling and simulation using Geographical Information Systems (GIS) with system dynamics applied to epidemiological phenomena” are presented. Specifically, a model to describe the critical factors in the propagation of epidemics is introduced. The model integrates the most common mathematical models used in epidemiology (SIR, SIRS, SIS) with georeferencing and simulation using different computational techniques. Pondered weight techniques are employed in the solution of a case study (asthma epidemics in New York).
Distributed network multi agent security system. Net-Mass
Authors: Horfan Álvarez Daniel , Mark Bailey Andrew , Gómez Blandón Lucas Adrián
Published: July 2024

Network security is one of the weakest and most sensitive areas within an organization, because it requires different strategies to protect vulnerable points as well as the coordination and distribution of efforts in order to encompass all the possible forms and points of computer attacks. In this article a distributed multiagent system is proposed as a tool to protect security in networks with different operating systems and which consequently are susceptible to diverse attacks. The system proposed is composed of heterogeneous autonomous agents with different characteristics in terms of their strategies of intruder detection and protection of primary network systems. It is planned that these agents will base their decisions on the application of different artificial intelligence techniques, such as expert system heuristics, evolutionary algorithms, and neural networks.
Impact of digital television in Colombia
Authors: Acosta Osorio Miller , Moreno Mogollón Jaime Alberto , Monclou Salcedo Álex Alberto
Published: July 2024

El problema fundamental de la señal análoga de televisión consiste en que para mejorar la imagen se requiere más ancho de banda, pues para transmitir una imagen análoga de TV, cada píxel debe estar incluido en la señal. En este trabajo se hace un análisis de la televisión digital (DTV).
Para facilitar la compresión de todo el sistema DTV, se siguió un orden lógico y secuencial de todo el proceso, desde la digitalización de la señal hasta su emisión, teniendo en cuenta que se busca transmitir varios programas de televisión digital sobre un solo canal de RF. Así mismo, se estudió el proceso de recepción considerando los estándares disponibles y se realizó un análisis sobre la situación colombiana.
Analysis of the relevant parameters for the design and optimization of a radiant tube
Authors: Amell Arrieta Andrés , Copete López Henry , Gómez Juan Pablo
Published: July 2024

The need for adopting the latest technological tendencies in combustion appliances, which have potential applications in the national industry, gives rise to an interest in studying the parameters of design, optimization and characterization of new thermal systems. A method for the analysis of heat transfer processes involving radiant tubes is presented in this article. Some hypotheses used in the development of the model considered helpful for the characterization of the most influencing parameters involved in the model are presented. The model attempts to serve as a guide during the design phase in industrial applications, and to be an adequate tool for the selection of a combustion system with radiant tube.
A comparative study of two rapid tooling technologies; Coproinmold – Selective Laser Sintering
Authors: Coba Salcedo Milton , Serres Moliner Esther
Published: July 2024

Rapid tooling (RT) is the technology that implements rapid prototyping (RP) techniques in the fabrication of tools and molds, especially for injection of plastics. Recently, RT has gained importance to the point that it is already considered to be a viable alternative to the methods of conventional machining. Two important techniques of RT are compared in this paper. This comparison is based on experimental data on the surface texture, dimensional quality, life cycle, costs and time of development of the tooling.
Nopol synthesis from β-pinene and turpentine oil over Sn-MCM-41
Authors: Alarcón Durango Edwin Alexis , Villa Correa Aída Luz , Montes de Correa Consuelo
Published: July 2024

Nopol was obtained by the Prins condensation of β-pinene and paraformaldehyde over Sn-MCM-41. The catalyst was synthesized by chemical vapor deposition using a Sn salt over MCM-41. Reactions were carried out using either high purity β-pinene or turpentine oil as a starting material. The effect of catalyst Sn loading, temperature, type of solvent, catalyst amount, and reaction time on nopol selectivity was studied. Catalyst samples were characterized by XRD, IR, UV-VIS, elemental analysis and BET surface area. Low Sn loaded Sn-MCM-41 yields near 100% nopol with high purity β-pinene; whereas using turpentine as β-pinene source, nopol selectivities up to 93% were attained for equimolar ratios of reactants.
Liquid-liquid extraction of barium with DEPHA: chemical equilibrium
Authors: Duperly Yaruro Gladis , Laverde Cataño Dionisio Antonio , Escalante Hernández Humberto
Published: July 2024

The objective of this work was to evaluate a liquid - liquid extraction process to separate barium in aqueous phase by means of an organic phase consisting of DEPHA (bis-2-ethylhexyl phosphate) in kerosene and isopropyl alcohol as modifying agent. Different variables were studied: a) metal concentration in the liquid phase, b) pH of the solution, c) concentration of the organic carrier and d) ratio of the organic to aqueous phase volume. A recovery efficiency of 89.5% was obtained using an organic solution based on DEPHA, 30% (V/V) and isopropyl alcohol, 30% (V/V) as selective extraction medium. The extraction of barium occurs at pH 11. A solution containing 100 mg/L of BaCl2.2H2O was used as aqueous phase. The chemical equilibrium present in the system was described and the parameter KqE = 0.338 was obtained. This parameter is useful for establishing the viability of the industrial barium separation process in the aqueous phase.
The temperature of compacting and energy influence in dynamics properties of an asphalt mixture
Authors: Reyes Ortiz Óscar Javier , Camacho Tauta Javier Fernando , Reyes Lizcano Fredy Alberto
Published: July 2024

The temperature of asphalt mixtures varies significantly from the plant production to in-situ formation of the pavement structure, especially during the compacting process. Temperature differences from point to point generate segregation, mi- crofissures, and, especially, changes in the mechanical and dynamic properties of the mixture. In this laboratory study the effect of the temperature during the compacting process on the dynamic module, density, stability and flow of an asphalt mixture with gradation 0/10 and asphalt with penetration 60/70 was determined. When the compacting process was conducted at 100 and 150 oC reductions of: around 30%, 5% and 50% were obtained for dynamic module, density and stability, respectively.
The induction generator with two triphases windings in stator
Authors: Müller Valentin
Published: July 2024

This paper shows the performance of an induction generator with two triphases windings in stator, and the choice of a suitable angle between the two windings in stator for getting a proper tension according to the value of the consumer connected at the generator terminals.
Pyrometer at low radiation for measuring the forehead skin temperature
Authors: Pezzotti Gianni , Coppa Paolo , Liberati Fabrizio
Published: July 2024

This paper presents the results of the design, construction, calibration and tests of a low radiation pyrometer for temperature measurement of the human body. The instrument is based on a low cost thermopile as detector and an optical system. It is specially designed to measure the forehead temperature of a person. It is useful in applications like: Measurement of temperature of people in the airports (to prevent contamination with contagious diseases infection) or applications in medicine as continuous monitoring of the temperature of patients in intensive care units at hospitals. The instrument has been calibrated using an on-purpose-built black body and its precision is of 0.19 °C.
The nitrogen/phosphorus and the succession of phytoplankton in two lakes located in the alluvial prairie of main river in Germany
Authors: Aguirre Néstor , Werding Bernd , Palacio Jaime
Published: July 2024

Variation in seasonal nitrogen/phosphorus ratio and phytoplankton community succession were compared between March and November 1997 in a lake directly connected to the Main River and in another lake without direct connection. Results showed a massive growth of Cyanophyta during summer in association with low N/P ratios (10-5:1), whereas Crysophyta and Chlorophyta abundance was accompanied by high N/P ratios (50-20:1). Evidences suggest that composition and structure of the phytoplankton community are related to phosphorus and nitrogen availability, and also contributes to the appearance of new phytoplanktonic species. However phytoplanktonic community succession were more correlated with the dominance degree of some species.
Editorial
Authors: Universidad de Antioquia Revista Facultad de Ingeniería
Published: July 2024

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Production of a coal-based activated material from anthracite and its potential applications in hydrometallurgy
Authors: Estupiñán Hugo Armando , Vásquez Quintero Custodio , Pulido Jorge Enrique
Published: July 2024

Activated carbon was obtained from an anthracite mineral (96,6 wt % of fixed carbon) from the Páramo del Almorzadero (town of Cerrito, Santander). The anthracite was activated in two stages: firstly, a chemical activation with acids was used for increasing the reactivity of the external surface and facilitating the access to the internal surface of the coal. Secondly, a physical activation at temperature of 800 oC, 1.000 oC and 1.200 oC with CO2 was conducted. The effect of the operating conditions during the activation process on the activity of the coal was evaluated, and the optimum conditions to achieve a product with the better characteristics, i.e., a specific surface of 107,4 m2/g, were obtained. The potential of this activated coal in hydrometallurgy (specifically in recovery of gold) was evaluated. A gold adsorption capacity of 6,6 kg/ton of activated coal was obtained.
Potential applications of portland cement on bone tissue engineering. Phase I: biocompatibility studies–calcium hydroxide effects
Authors: Gallego Daniel , López Luis Ernesto , Hansford Derek , Klemas Jonas
Published: July 2024

There is an increasing and unfulfilled demand of bone substitutes with optimal mechanical and biological properties. Based on the excellent mechanical and structural properties of Portland Cement, a biocompatibility exploratory study of this material was proposed. Plain substrates were fabricated with Gray Type I Portland Cement under different conditions (Neutralized-SN, Carbonated-SC, not neutralized-SnN), which were then used to conduct a Direct Contact Assay with CHO and HOS cells for 24h. The substrates were characterized by SEM, and phenolphthalein assays to determine the pH value, while the cell culture assays were evaluated by Phase Contrast Microscopy. The results show that SnN had the highest pH value (> 12,0), followed by SN, and finally by SC (≈ 7,4); it was also observed that the cytotoxicity of the substrates diminished in proportion to the pH value. It is proposed that the cytotoxicity of Portland Cement is caused by the Ca(OH)2 formed during the hydration of this material. Thus, by lowering the amount of Ca(OH)2, either by carbonation or neutralization, the biocompatibility of the material is positively affected.
Preparation, characterization and evaluation of MgO for flameless combustion of natural gas
Authors: Gómez Macías Elías , Jaramillo Alejandro , Múnera John , Sánchez Mauricio
Published: July 2024

A MgO catalyst was prepared by aqueous dispersion of commercial magnesium oxide followed by drying and calcination to obtain a thermally-stabilized material. Fresh and used solid samples were characterized by XRD, BET surface area, and SEM-EPMA, which revealed a MgO matrix with periclase structure containing CaO on the surface. Catalytic activity tests were conducted in a fixed-bed reactor packed with MgO particles. Natural gas – air mixtures fed to the reactor were maintained below the LFL. Different flow rates and inlet temperatures were evaluated, and CH 4, CO2 and CO concentrations in the effluent stream were measured with a NDIR analyzer. The temperature required to achieve total methane conversion was increased as the flow rate of the reacting mixture increased. A low-cost, thermally-stable catalytic combustion system aimed at highly-efficient combustion of natural gas can be developed based on the results of this study. Moreover, this system would eliminate problems related with stability, security and environmental effects inherent to conventional thermal combustion processes.
Catalytic effect of LeachWell 60X® and Pb+2, S-2 ions in electrochemical cyanidation of gold from sulfured minerals
Authors: Mendoza Villabona Olger Giovani , Pedraza Rosa Julio Elías
Published: July 2024

Extraction of gold from sulfur minerals by cyanidation is a difficult process. The effect of a catalyst (LeachWell 60X® LW) and Pb2+, as well as the inhibiting effect of S2-, on the performance of the extraction of gold by cyanation was studied. The anodic oxidation of gold and the cathodic reduction of oxygen, both under conventional cyanidation (1.000 p. p. m. of CN- and a oxygen-deficient environment, 5,2 p. p. m.) and “enhanced” cyanidation (25.000 p. p. m. of CN- and oxygensaturated environment, 24 p. p. m.) were studied by linear- and cyclic-scan potentiodynamic methods. Results indicate that Pb2+ and LW display similar behavior, and confirm a significant inhibiting effect of S-2 even at low concentrations (0,5 – 10 p. p. m.). The significant increase in the overall dissolution rate was attributed mainly to the increase in the rate of oxygen reduction.
Study of blends from recycled polymer for properties improvement
Authors: Gallego Kelly , López Betty Lucy , Gartner Carmiña
Published: July 2024

Polypropylene (PP) presents low impact resistance at low temperatures and easily undergoes thermal degradation. On the other hand, polyethylene terephtalate (PET) is very hygroscopic. One way to overcome these weaknesses is to blend both polymers trying to reach a good interaction through the insertion of polar functional groups within the PP backbone chain. In this study, recycled PP was grafted with maleic anhydride (AM), and the insertion was quantified by measuring carbonyl index with a Fourier Transform Infrared Spectrophotometer (FTIR). Rheometer blends were prepared using recycled PP (grafted and ungrafted) with recycled PET and their compatibility was analyzed using scanning electron microscopy (SEM) and differential scanning calorimeter (DSC). Other properties such as hardness and water absorption were also measured. It was concluded that grafting recycled PP made it more compatible with recycled PET.
The importance of RID and P Vs h curves on indentation studies of TiN films deposited onto M2 and 304L steels
Authors: Meza J. M. , Devia A. , Vélez J. M.
Published: July 2024

A hardness study of TiN films onto M2 and 304L steels applied by PAPVD was conducted in this work. Instrumented indentation and hardness equipments allow to asses this property. Crack patterns produced during these tests were correlated with this information. In addition, from the P-h/t (Load-displacement/film’s thickness) plots, called Relative Indenter Displacement plots, and P-h plots important information was obtained about the capacity of these systems for supporting load. Both graphics showed to be of great importance for understanding the mechanical response of these systems to indentation.
TiAlN films on ASTM A36 steel for sputtering reactive process RF
Authors: Quesada Franz , Mariño Álvaro
Published: July 2024

TiAlN films were deposited on ASTM A36 steel by RF reactive sputtering process using a TiAl (60/40%) target. Films were sputtered at two different relative pressures, 0,05 and 0,1, keeping constant the Argon pressure. The films were deposited on samples with different pretreatments: as received material, hardened and quenched, plasma-nitrided, and with initial coatings of Ti and TiN. Film deposition was conducted at 230°C. The TiAlN films showed composition Ti0.4Al0.6N with preferred orientation (200). The best properties of hardness, corrosion resistance, and wear resistance were observed at a relative pressure of 0,1 and best adherence at a relative pressure of 0,05. The highest was 2500 HK.
Fatigue behaviour of a glass coating on Ti6AL4V for biomedical applications
Authors: Pavón Juan José , Jiménez-Piqué E. , Anglada M. , Saiz E. , Tomsia A. P.
Published: July 2024

The fixation of bone replacement implants to the hosting tissue can be improved if the implants have a bioactive surface that can precipitate hydroxyapatite in vivo. Titanium alloys, despite their desirable mechanical and nontoxic properties, are not bioactive and, therefore, do not bond directly to the bone. One of the ways to change a bioinert metallic surface is to coat it with a bioactive material. This work presents the evaluation of the fatigue behaviour by Hertzian (spherical) indentation of a glass coating on Ti6Al4V. This coating belongs to the SiO2-CaO-MgO-Na2OK2O- P2O5 system and, despite it can be used for corrosion protection, it has been specifically designed to be used as the inner layer of a bioactive bilayer coating with an outer layer of lower SiO2 content to ensure bioactivity. Hertzian monotonic tests allowed to obtain a damage sequence starting with three brittle damage events (ring, cone and radial cracking) followed by coating delamination associated to the plastic deformation of the substrate. The first brittle damage, ring cracking, was used as criteria for the evaluation of the stress-corrosion and cyclic loading cracking behaviour in air and in distilled water environments. Results showed sensitivity of the coating to degradation under both static and cyclic loadings which was considerably larger in distilled water due to the corrosion susceptibility of this glass. Delamination damage was also sensitive to Hertzian cyclic loading showing two different mechanisms depending of the maximum
Methodology for the evaluation of antifouling paints performance in static conditions
Authors: Echeverría Félix , Castaño Juan G. , Aguirre Néstor , Valderrama Ana C. , Peña Juan D. , Herrera Liz , Giudice Carlos , Morales Alfredo
Published: July 2024

Biofouling is an important aspect to consider in the protection of a structure submerged in sea water. In fact, besides causing deterioration of the entire protective system (e. g., corrosion protection), biofouling increases roughness and weight in ships and other structures therefore affecting their operation. Antifouling paints, having the capacity to exclude the marine organisms that tend to adhere to the surface, have been developed in order to mitigate these adverse effects. In order to formulate and evaluate a potential paint it is necessary to have knowledge of the marine environment, and to be able to conduct both laboratory and field tests so representative and applicable results are obtained. The recommended steps to follow in such a study are described in this paper. The methodology proposed has been recently developed and applied with promising results.
Assesment of thermodynamic adhesion work on AISI 4140 steel plates and rolling bearing liners with anaerobic adhesives
Authors: García Germán , Casanova Herley , Araque Pedronel , Toro Alejandro
Published: July 2024

The thermodynamic adhesion work of AISI 4140 flat plates and AISI 52100 steels in contact with two commercial anaerobic adhesives was evaluated by measuring the advancing and receding contact angles in an immersion-emersion tensiometer. The polar and non-polar adhesive components were calculated by the van Oss method for all the adhesive-metal pairs tested. The effect of the application of a primer on the metal surface was also considered. The results showed that application of the primer nada significant effect on the wettability of adhesives, although the adhesion work remained practically unchanged with respect to the pure adhesive-metal joints. On the other hand, major differences on the response of the two commercial were observed between the two commercial adhesives studied, mainly as a consequence of their chemical composition and rheological properties.
Simulation of melting process and net diagrams for the Cupola Furnace of the University of Antioquia
Authors: Aristizábal Sierra Ricardo Emilio
Published: July 2024

The best values of the adjustable parameters of the AFS Cupola Model for modeling the cupola furnace of University of Antioquia were obtained form experimental data. Generalized net diagrams were simulated and developed for this unit. Profiles of temperature, gas phase concentrations and carbon content in the metal were obtained. The net diagrams include the basic generalized net diagram, with ambient temperature blasting and without oxygen enrichment. In addition, the behavior of production and temperature of metal at the tap hole under preheated blasting and oxygen enrichment was analyzed. This analysis allowed us to demonstrate the advantages of working under those conditions. The value of the parameters used to adjust the software was in agreement with their inherent physical meaning. Moreover, the software predictions (E.G, profiles and the diagram) agree with the experimental observations. The possibility to build net diagrams for other cupola with the same procedure highlighted.
1-Butanol dehydration as catalytic test to determine acidity of solid acids
Authors: Pérez Oliveros Jaime Olmedo , Molina García Bibiana del Carmen
Published: July 2024

Catalytic dehydration of 1-Butanol was used as a test reaction to determine the nature of acid sites on several samples: undoped and doped sulfated-zirconia (dopants: Ce, W, or Sb), ZSM-5, Al-MCM-41 and permutite (amorphous aluminosilicate). Acid strength for each sample was ranked according to its catalytic activity. Catalysts exhibiting similar activity can be compared by the isomer ratios: cis-butene/trans-butene (CB/TB), 1-butene/trans-butene (1B/TB), and isobutene/ trans-butene (IB/TB). It was found that the activity of the sulfated-zirconia was directly proportional to the sulfate content. Interestingly, Al-MCM-41 exhibits similar acidity to the best sulfated-zirconia sample.
Laboratory studies of the degradation of chlorpyrifos pesticide in soils supplemented by the fungus phanerochaete chrysosporium
Authors: Lopera Mesa Margarita María , Peñuela Mesa Gustavo Antonio , Domínguez Gual María Carolina , Mejía Zapata Gloria María
Published: July 2024

Degradation of the insecticide chlorpyrifos was investigated in sterilized soil samples supplemented by the white rot basidiomycete Phanerochaete chrysosporium. Degradation rates were measured during 21-day incubation at pesticide concentrations of 0,95, 5,3, and 9,4 µg/g. Phanerochaete chrysosporium showed ability to biodegrade the insecticide in values of 96,3%, 82,4% and 62,2%, respectively, followed by rapid degradation at low initial concentration of chlorpyrifos.
Total suspended particles (TSP) and breathable particles (PM10) in Aburra Valley, Colombia
Authors: Saldarriaga Molina Julio César , Echeverri Londoño Carlos Alberto , Molina Pérez Francisco José
Published: July 2024

In the Aburra’s valley, nor-western region of Colombia, inhabited by 3 million people, crossed by 400,000 vehicles; with the presence of establishments of industrial sectors: textile, foods and metal-mechanical; The concentrations of total suspended particles (PST) and breathable particles (PM10), were evaluated, during the period: December of 2000 to June of 2001. The determinations of PST and PM10, were performed in ten stations, distributed of north to the south, covering urban and rural zones with the municipalities of: Girardota, Bello, Medellín, Itagüí, Sabaneta and Caldas. When analyzing relation PM10/PST, was that the best statistical correlations are located in the zones center and the south of the valley. In addition the increasing tendency in relation PM10/PST was observed, from 0.527 for the rural station Girardota (North), to 0.813 in the urban station Caldas (South). This gradient in relation PM10/PST apparently this related to the wind regime that predominates in the Valley of Aburrá with direction the northsouth, which causes that the fine particles migrate of north to the south, increasing relation PM10/PST in the same direction.