Bubble and Dew Point Calculations in Multicomponent and Multireactive Mixtures

Bubble and dew point calculations are useful in chemical engineering and play an important role in the study of separation equipments for non-reactive and reactive mixtures. To the best of the authors’s knowledge, few methods have been proposed for these calculations in systems with several chemical reactions. The objective of this paper is to introduce new conditions for performing bubble and dew point calculations in reactive mixtures. We have developed these conditions based on the application of transformed variables of Ung and Doherty (1995). Using these transformed variables, the solution space is restricted to compositions that are already at chemical equilibrium and by consequence the problem dimension is also reduced. The reliability and efficiency of three equation-solving methods are tested and compared using our equilibrium conditions: a) a simultaneous equation-solving approach using Newton method (SESN), b) an equation-decoupling approach using successive substitution method (EDSS) and c) an optimization approach using the stochastic optimization method Simulated Annealing(OSA). Our results indicated that even for simple reactive systems, bubble and dew point calculations are challenging for classical equation-solving methods and require robust strategies. We conclude that OSA and EDSS methods are reliable to locate bubble and dew points in reactive systems. EDSS is more efficient than OSA; however, OSA does not need initial guesses and is more suitable for difficult problems

Gibbs Energy Minimization Using Simulated Annealing for Two-phase Equilibrium Calculations in Reactive Systems

Phase equilibrium calculations in systems subject to chemical reactions are involved in the design, synthesis and optimization of reactive separation processes. Until now, several methods have been developed to perform simultaneously physical and chemical equilibrium calculations. However, published methods may face numerical difficulties such as variable initialization dependence, divergence and convergence to trivial solutions or unstable equilibrium states. Besides, these methods generally use conventional composition variables and reactions extents as unknowns which directly affect the numerical implementation, reliability and efficiency of solving strategies. The objective of this work is to introduce and test an alternative approach to perform Gibbs energy minimization in phase equilibrium problems for reactive systems. Specifically, we have employed the transformed composition variables of Ung and Doherty and the stochastic optimization method Simulated Annealing for two-phase equilibrium calculations in reacting systems. Performance of this strategy has been tested using several benchmark problems and results show that proposed approach is generally suitable for the global minimization of transformed Gibbs energy in reactive systems with two-phase equilibrium

Solubility of CO2 in three cellulose-dissolving ionic liquids

The solubility of CO2 in three cellulose-dissolving ionic liquids (1-ethyl-3-methylimidazolium diethylphosphate, [Emim][DEP], 1-allyl-3-methylimidazolium chloride, [Amim][Cl], and 1-butyl-3-methylimidazolium chloride, [Bmim][Cl]) at temperatures within 298 and 356 K and pressures up to 6.5 MPa was determined using a Van Ness-type apparatus (static isochoric). It was demonstrated that this device can work in isothermal and isoplethal modes, being the latter faster and more precise. Moreover, it was possible to determine CO2 solubilities in metastable liquid [Bmim][Cl]. Experimental data were modeled using the Extended Henry's law correlation and the group contribution equation of state. New parameters for the binary interaction of CO2 with ionic liquid groups were calculated.Fil: Pérez, Eduardo. Universidad de Valladolid; EspañaFil: de Pablo, Laura. Universidad de Valladolid; EspañaFil: Segovia, J. Juan. Universidad de Valladolid; EspañaFil: Moreau, Alejandro. Universidad de Valladolid; EspañaFil: Sánchez, Francisco Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química; ArgentinaFil: Bermejo, María Dolores. Universidad de Valladolid; Españ

Diffusive and Arrestedlike Dynamics in Currency Exchange Markets

This work studies the symmetry between colloidal dynamics and the dynamics of the Euro–U.S. dollar currency exchange market (EURUSD). We consider the EURUSD price in the time range between 2001 and 2015, where we find significant qualitative symmetry between fluctuation distributions from this market and the ones belonging to colloidal particles in supercooled or arrested states. In particular, we find that models used for arrested physical systems are suitable for describing the EURUSD fluctuation distributions. Whereas the corresponding mean-squared price displacement (MSPD) to the EURUSD is diffusive for all years, when focusing in selected time frames within a day, we find a two-step MSPD when the New York Stock Exchange market closes, comparable to the dynamics in supercooled systems. This is corroborated by looking at the price correlation functions and non-Gaussian parameters and can be described by the theoretical model. We discuss the origin and implications of this analogy

Wear behaviour of WC plasma sprayed coatings wi th micro and nanostructured powders

El objetivo de este trabajo es estudiar el comportamiento a desgaste de distintos recubrimientos de WC sobre acero inoxidable mediante proyección por plasma atmosférico. Se proyectan dos tipos de polvos comerciales con base cobalto (12 %) y níquel (10 %), con el objeto de analizar la influencia de la matriz e incluso del espesor del recubrimiento. Los recubrimientos obtenidos se caracterizan microestructuralmente por microscopía electrónica de barrido y difracción de rayos X. La caracterización tribológica de los recubrimientos se realiza mediante ensayos pin-on-disc contra bolas cerámicas de alúmina (2.400 HV) y nitruro de silicio (1.600 HV), sin lubricación, obteniéndose las tasas de desgaste y la evolución del coeficiente de rozamiento. Las pistas de desgaste y los residuos generados se caracterizaron mediante Microscopía Electrónica de Barrido, MEB. Los resultados muestran diferentes mecanismos de desgaste en cada par de material ensayado en función de la matriz y de la naturaleza de la bola empleada en el ensayo, encontrándose mayores tasas de desgaste con bola de nitruro de silicio. En una segunda fase, se obtienen recubrimientos, con dos polvos base cobalto cuyos tamaños de partícula son micrométrico y nanométrico, respectivamente, con el objetivo de estudiar la influencia del tamaño de partícula inicial sobre las propiedades a desgaste del recubrimiento. Los resultados obtenidos ponen de manifiesto una mayor resistencia al desgaste de los recubrimientos obtenidos con polvos nanoestructurados, bajo condiciones de carga elevadas, mientras que para cargas bajas ambos recubrimientos presentan un comportamiento similar a pesar de las diferencias microestructurales apreciadasThe aim of the present work is the study of wear behaviour of different WC coatings deposited on stainless steel substrate by means of atmospheric plasma spraying (APS). Two types of WC commercial powders, with different metal binder (12% Cobalt and 10% Nickel) have been deposited in order to analyse the influence of the metal matrix and thickness of the coating in tribological properties.The microstructure of the depositions was characterized using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). On the other hand, tribology characterization of the coatings was made by pin-on-disk wear tests against alumina (2400HV) and silicon nitride (1600HV) ceramic balls, without lubrication. Wear rates and friction coefficient evolution have been calculated. Finally, wear tracks and wear debris have been analysed with the help of SEM.The results of each pair of tested materials show different mechanisms of wear related to the nature of the ball that has been used, obtaining higher wear rates with silicone nitride ball..In a second phase of the study, in order to examine the influence of the initial particle size on the wear properties of the coatings, cobalt based coatings have been analysed with different initial particle size (micrometric and nanometric particles).Results show that nanostructured coatings have higher wear resistance than microstrutured ones for high loads. However for low loads, behaviour is similar in spite of the microstructural differences appreciate

Inherently Safer Design and Optimization of Intensified Separation Processes for Furfural Production

Currently furfural production has been the subject of increased interest because it is a biobased chemical able to compete with fossil-based chemicals. Furfural is characterized by flammability, explosion, and toxicity properties. Improper handling and process design can lead to catastrophic accidents. Hence it is of most importance to use inherent safety concepts during the design stage. This work is the first to present several new downstream separation processes for furfural purification, which are designed using an optimization approach that simultaneously considers safety criteria in addition to the total annual cost and the eco-indicator 99. The proposed schemes include thermally coupled configuration, thermodynamic equivalent configuration, dividing-wall column, and a heat integrated configuration. These are compared with the traditional separation process of furfural known as the Quaker Oats Process. The results show that because of a large amount of water present in the feed, similar values are obtained for total annual cost and eco-indicator 99 in all cases. Moreover, the topology of the processes has an important role in the safety criteria. The thermodynamic equivalent configuration resulted as the safest alternative with a 40% reduction of the inherent risk with respect to the Quaker Oats Process, and thus it is the safest option to purify furfural

Culture-free genome-wide locus sequence typing (GLST) provides new perspectives on Trypanosoma cruzi dispersal and infection complexity

El análisis del polimorfismo genético es una poderosa herramienta para la vigilancia epidemiológica y investigar. Sin embargo, la inferencia poderosa de la variación genética del patógeno es a menudo restringido por el acceso limitado al ADN objetivo representativo, especialmente en el estudio de especies parásitas obligadas para las cuales el cultivo ex vivo requiere muchos recursos o es propenso a sesgos. Los métodos modernos de captura de secuencias permiten analizar directamente la variación genética de los patógenos del material del huésped/vector, pero a menudo son demasiado complejos y costosos para entornos de escasos recursos donde prevalecen las enfermedades infecciosas. Este estudio propone un método sencillo y rentable Herramienta de tipificación de secuencias de locus de todo el genoma (GLST) basada en la amplificación paralela masiva de puntos críticos de información en todo el genoma del patógeno objetivo. el multiplexado La reacción en cadena de la polimerasa amplifica cientos de objetivos genéticos diferentes definidos por el usuario en un único tubo de reacción y la posterior limpieza basada en gel de agarosa y código de barras completan la preparación de la biblioteca por menos de 4 USD por muestra. Nuestro estudio genera un modelo flexible Flujo de trabajo de diseño de panel de imprimación GLST para Trypanosoma cruzi, el agente parásito de Chagas enfermedad. Aplicamos con éxito nuestro panel GLST de 203 objetivos a extractos nómicos metagénicos directos y sin cultivo de vectores triatominos que contienen un mínimo de 3,69 pg/μl de ADN de T. cruzi y elaborar más sobre el rendimiento del método mediante la secuenciación de bibliotecas GLST de T. cruzi clones de referencia que representan unidades de tipificación discretas (DTU) TcI, TcIII, TcIV, TcV y TcVI. Los 780 sitios SNP que identificamos en el conjunto de muestras distinguen parásitos de forma repetitiva infectar vectores simpátricos y detectar correlaciones entre distancias genéticas y geográficas a escala regional (< 150 km), así como continental. Los marcadores también separan claramente TcI, TcIII, TcIV y TcV + TcVI y parecen distinguir infecciones multiclonales dentro de TcI. Discutimos las ventajas, limitaciones y perspectivas de nuestro método a través de un espectro de la investigación epidemiológica.Analysis of genetic polymorphism is a powerful tool for epidemiological surveillance and research. Powerful inference from pathogen genetic variation, however, is often restrained by limited access to representative target DNA, especially in the study of obli gate parasitic species for which ex vivo culture is resource-intensive or bias-prone. Mod ern sequence capture methods enable pathogen genetic variation to be analyzed directly from host/vector material but are often too complex and expensive for resource-poor set tings where infectious diseases prevail. This study proposes a simple, cost-effective ‘genome-wide locus sequence typing’ (GLST) tool based on massive parallel amplifica tion of information hotspots throughout the target pathogen genome. The multiplexed polymerase chain reaction amplifies hundreds of different, user-defined genetic targets in a single reaction tube, and subsequent agarose gel-based clean-up and barcoding com pletes library preparation at under 4 USD per sample. Our study generates a flexible GLST primer panel design workflow for Trypanosoma cruzi, the parasitic agent of Chagas disease. We successfully apply our 203-target GLST panel to direct, culture-free metage nomic extracts from triatomine vectors containing a minimum of 3.69 pg/μl T. cruzi DNA and further elaborate on method performance by sequencing GLST libraries from T. cruzi reference clones representing discrete typing units (DTUs) TcI, TcIII, TcIV, TcV and TcVI. The 780 SNP sites we identify in the sample set repeatably distinguish parasites infecting sympatric vectors and detect correlations between genetic and geographic dis tances at regional (< 150 km) as well as continental scales. The markers also clearly sep arate TcI, TcIII, TcIV and TcV + TcVI and appear to distinguish multiclonal infections within TcI. We discuss the advantages, limitations and prospects of our method across a spectrum of epidemiological research

Morbilidades del neurodesarrollo asociadas con el nacimiento pretérmino con peso ≤1500 gramos entre 1993 y 2011 en España: estudio de una muestra de 1200 casos

Objetivos: el parto muy prematuro puede originar discapacidades en múltiples dominios del desarrollo. Este artículo describe las morbilidades del neurodesarrollo que, según sus progenitores, presenta una muestra de 1202 niños/as nacidos/as con ≤1500 gramos entre 1993 y 2011 en España y destaca algunas de las variables que influyen en ellas. Métodos: encuesta multi-método realizada entre abril 2013 y junio 2014 con soporte CATI y CAWI. Previamente, se realizó un extenso trabajo de campo cualitativo. Resultados: el 44,2 % de la muestra presenta morbilidades ( 1,78 morbilidades por niño). Las más prevalentes son los trastornos del aprendizaje (34,4 % de los casos) y el trastorno por déficit de atención e hiperactividad (31,5 %). En este período, se produce un incremento relativo de morbilidades temporales frente a permanentes. Conclusiones: el porcentaje total de niños con morbilidades disminuye moderadamente entre 1993 y 2011. Las variables biológicas y médicas explicarían mejor que las familiares la presencia de morbilidades en esta población

Características clínicas del estado epiléptico en niños de un hospital de tercer nivel de Lima.

Status Epilepticus (SE) in children exhibits high levels of morbidity and mortality and has been poorly studied in Perú. Objective: To describe the frequency and clinical characteristics of children with Status Epilepticus treated at Cayetano Heredia Hospital in Lima. Material and Methods: Retrospective and observational study, case series type, in children under 14 years of age, with Status Epilepticus treated between January and December of 2021. Results: SE was recorded in 28.8% of children with epileptic seizures seen during 2021. Twenty-three children presenting 46 SEs were included. The median age was 2 years, the majority (73,9%) being males, with diagnosis of epilepsy or brain malformation (21.7%) and treated in the pediatric emergency (91%). The predominant semiological pattern was of generalized motor type (52.2%), with remote symptomatic etiology (73.9%), and EEG recorded in a 63% of all cases, mainly reported as normal (75,9%). The median duration was 22 minutes of total resolution, 7 minutes, and of partial resolution, 2 minutes. Midazolam was used as the first line of treatment (78%), and phenytoin as the second line (85%). Conclusions: SE was a frequent condition observed in children throughout the year 2021. Most affected children were male, the predominant etiology was remote symptomatic, and the most common semiological type was the generalized motor. The children were treated according to international management guidelines. A systematic epidemiological surveillance approach is highly encouraged.El estado epiléptico (EE) en niños exhibe altos niveles de morbi-mortalidad y ha sido poco estudiado en el Perú. Objetivo: Describir la frecuencia y características clínicas de niños con estado epiléptico, atendidos en el Hospital Cayetano Heredia de Lima. Material y métodos: Estudio retrospectivo y observacional, tipo serie de casos de niños menores de 14 años con diagnóstico de estado epiléptico, atendidos entre enero y diciembre de 2021. Resultados: Se registró EE en un 28,8% de todos los niños atendidos por crisis epilépticas durante el año 2021. Se incluyeron 23 niños que presentaron 46 EE, varones (73,9%), con una mediana de la edad de 2 años, diagnóstico subyacente de epilepsia o malformación cerebral (21,7%), atendidos en emergencia pediátrica (91%). El tipo semiológico predominante fue el EE motor generalizado (52,2%), con etiología sintomática remota (87%) y EEG registrado en un 63% de los casos, predominantemente de tipo normal (75,9%). La mediana de duración fue de 22 minutos, de resolución total, 7 minutos y resolución parcial, 2 minutos. Se empleó midazolam (78%) como primera línea de tratamiento y fenitoína (85%), como segunda línea. Conclusiones: El EE en niños fue una emergencia prevalente durante el año 2021. La mayoría fueron varones, cuya etiología predominante fue sintomática remota y el tipo semiológico más común fue el motor generalizado. Los niños fueron atendidos de acuerdo con las guías internacionales de manejo. Se insiste en la necesidad de un sistemático afronte de vigilancia epidemiológica