Nuevos aceros inoxidables dúplex fabricados por vía pulvimetalúrgica mediante sinterización asistida por campo eléctrico

El principal objetivo de este trabajo de investigación es determinar la viabilidad de los aceros inoxidables dúplex procesados por vía pulvimetalúrgica utilizando una técnica de sinterización asistida por campo eléctrico (Field-Assisted Sintering Technique, FAST). Mediante esta técnica de menor activación térmica y mayor velocidad de calentamiento y enfriamiento, se podría evitar la formación de fases frágiles. Se estimará la competitividad de estos nuevos aceros inoxidables dúplex en el mercado actual de los aceros. Por otro lado, se ha conseguido limitar con éxito el espesor de una zona de interdifusión entre las fases ferríticas y austeníticas, de la cual hay información en la literatura para el caso de aceros inoxidables dúplex sinterizados de manera tradicional y con contenidos en austenita superiores al 50 % en peso. Esta tercera fase es el resultado de la difusión durante un tiempo limitado de elementos de aleación, entre los que se encuentran principalmente el Ni y el Cr. Por lo tanto, en este proyecto se diseñan tres aceros inoxidables dúplex usando como materia prima dos polvos atomizados en gas, uno inoxidable austenítico (316L) y otro ferrítico (430L). Con el fin de incrementar la tenacidad y la resistencia a corrosión de estos aceros, la cantidad de austenita es siempre superior a 70 % en peso. Por consiguiente, se mezclan los polvos en una túrbula con el siguiente diseño de composición (% en peso): - Dúplex 1: 70 % AISI 316L – 30 % AISI 430L. - Dúplex 2: 80 % AISI 316L – 20 % AISI 430L. - Dúplex 3: 90 % AISI 316L – 10 % AISI 430L. Para evaluar viabilidad de los tres aceros inoxidables dúplex sinterizados por una técnica FAST, se consolidan los mismos por compactación asistida por campo eléctrico, que es una técnica basada en la aplicación simultánea de corriente alterna y presión para calentar las muestras por efecto Joule. Los aceros consolidados se analizan microestructuralmente y composicionalmente mediante Microscopía Electrónica de Barrido (MEB) unido al Análisis de Energía Dispersiva por rayos X. Además, se determinan sus propiedades mecánicas por nanoindentación y ensayos de tracción. Los resultados evidencian que se obtiene una densidad casi total, con una estructura homogénea y una baja porosidad. Estas características microestructurales conducen a unas magníficas propiedades mecánicas, en particular en el Dúplex 1, con un 70 % de porcentaje en peso de austenita.The main objective of this research is to determine the viability of processing duplex stainless steels (DSS) by a powder metallurgy (PM) route, including the use of a Field-Assisted Sintering Technique (FAST). The use of this technique , in which lower thermal activation values and higher cooling rates than in traditional PM techniques are involved, may lead to the suppression of the brittle phases. The competitiveness of these novel DSS, with respect to those being currently commercialised in the market, will be estimated. Furthermore, the thickness of an interface located between the ferrite and the austenite phases, which was reported in the literature in the case of DSS sintered by traditional ways and with an austenitic content superior to 50 wt. %, is successfully limited in the present work. This phase is the result of a limitation in the time available for the diffusion of the alloying elements, mainly Ni and Cr, which are the principal contributors to the existence of this third phase. Thus, in this investigation three new DSS are designed using commercial gas atomised austenitic (AISI 316L) and ferritic (430L) stainless steel powders as raw materials. In order to increase the toughness and the corrosion resistance of DSS, the quantity of austenite introduced is always higher than 70 wt. %. Therefore, the powders were mixed in a turbula mixer following the next designed compositions (in wt. %): - Duplex 1: 70 % AISI 316L – 30 % AISI 430L. - Duplex 2: 80 % AISI 316L – 20 % AISI 430L. - Duplex 3: 90 % AISI 316L – 10 % AISI 430L. To assess the viability of sintering these duplex stainless steels by a FAST technique, the consolidation is performed by Field-Assisted Hot Pressing, which is a technique based on the simultaneous application of an alternating current and a pressure to heat the sample by a Joule effect. The FAHP-DSS are microstructurally and compositionally analysed by Scanning Electron Microscopy (SEM) coupled to Energy Dispersive X-ray analysis (EDX). Moreover, their mechanical properties are determined by nanoindentation and tensile tests. The results highlight that almost full-density consolidated samples are obtained, with homogenous microstructure and low porosity. These microstructural characteristics lead to outstanding mechanical properties, in particular in the case of the Duplex 1, with 70 wt. % of austenitic phase.Ingeniería Industria

Analysis of the interface and mechanical properties of field-assisted sintered duplex stainless steels

The development of duplex stainless steels produced by powder metallurgy represents an interesting alternative to conventional fabrication routes, since typical routes imply a strict control of composition and temperature during the processing path in order to avoid undesirable brittle phases. This work proposes a sintering route, designated as field-assisted hot pressing technique, in which an alternating current is applied to consolidate duplex stainless steels with different initial austenite percentages, always higher than ferrite. In all the cases, a thin and hard planar interface composed by two different microconstituents is generated between austenite and ferrite, growing inside the ferritic phase. The good mechanical properties achieved by these field-assisted sintered duplex stainless steels, in terms of nanohardness, elastic modulus, yield strength, ultimate tensile stress and ductility, establish these steels as promising candidates to be introduced in the market.This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. The authors wish to express their gratitude to Dr. M.A. Monclús and Dr. M. Castillo-Rodríguez for their experimental and technical suppor

Healthcare workers hospitalized due to COVID-19 have no higher risk of death than general population. Data from the Spanish SEMI-COVID-19 Registry

Aim To determine whether healthcare workers (HCW) hospitalized in Spain due to COVID-19 have a worse prognosis than non-healthcare workers (NHCW). Methods Observational cohort study based on the SEMI-COVID-19 Registry, a nationwide registry that collects sociodemographic, clinical, laboratory, and treatment data on patients hospitalised with COVID-19 in Spain. Patients aged 20-65 years were selected. A multivariate logistic regression model was performed to identify factors associated with mortality. Results As of 22 May 2020, 4393 patients were included, of whom 419 (9.5%) were HCW. Median (interquartile range) age of HCW was 52 (15) years and 62.4% were women. Prevalence of comorbidities and severe radiological findings upon admission were less frequent in HCW. There were no difference in need of respiratory support and admission to intensive care unit, but occurrence of sepsis and in-hospital mortality was lower in HCW (1.7% vs. 3.9%; p = 0.024 and 0.7% vs. 4.8%; p<0.001 respectively). Age, male sex and comorbidity, were independently associated with higher in-hospital mortality and healthcare working with lower mortality (OR 0.211, 95%CI 0.067-0.667, p = 0.008). 30-days survival was higher in HCW (0.968 vs. 0.851 p<0.001). Conclusions Hospitalized COVID-19 HCW had fewer comorbidities and a better prognosis than NHCW. Our results suggest that professional exposure to COVID-19 in HCW does not carry more clinical severity nor mortality

XVII International Congress of Control Electronics and Telecommunications: "Advanced Science, Technology and Innovation to move towards a new socio-technical system: Sustainable Social Transformation"

Contenido: Approach to the diagnostic of cesarean birth using bio-inspired models. ; Design of a tool in a virtual reality environment to manipulate anatomical models. ; The effect of COVID-19 restrictions on the electricity price forecasting models. ; Depression prevention through artificial intelligence. ; State of the art in Prototypes as complements to the learning of the Colombian Sign Language (LSC). ; A computational proposal for gene expression deterministic analysis in associated disorders to depression and anxiety. ; Evaluation of postural stability from the predictability of the measurement of the center of pressure. ; Psychophysiological Analysis of Sound Stimuli.; Delphi method for the identification of relevant variables in the development of low-power photovoltaic solar projects. ; Socioeconomic impact of a refrigerator powered by a photovoltaic system in La Guajira. ; Energy Efficiency: characteristics that allow the reduction of greenhouse gases in. ; Possibilities for the implementation of a bioreactor from organic waste. ; Energy Potential with Small Hydroelectric Power Plants in Non- interconnected Zones of Colombia. ; Energy Potential in Photovoltaic Solar Solutions in Non-Interconnected Areas of Colombia. ; Photovoltaic system, towards the energy transition from home. ; Blockchain model to increase the transparency of public sector processes. ; Intelligent agricultural irrigation prescription system based on sensor networks and crop modeling. ; Design and implementation of a digital modulation classification system using intelligent algorithms. ; A mobile application proposal to minimize intermediation during agricultural process distribution of products in supply chain. ; Accompanying strategy for the social appropriation of new technologies in vulnerable agricultural communities: case in communities producing Gulupas fruits (Passiflora edulis Sims). ; Predictive model of transparency as an indicator of Public Policies. ; Smart system for recognition of ripening level in blackberry fruits. ; Project-based learning as an alternative methodology for technological education in electronics. ; Design and construction of an automated system for N. ; Four bar mechanisms (FBM) and their Software-Based applications: a reviewFT aquaponic culture of Red Carp and Crespa Lettuce. ; Intelligent search implementation for the construction of states of the art: a python application. ; Indoor and Outdoor propagation models on 5G environments: state of the art. ;The electronic detection of offenders (DOO) in the District Secretary of mobility of Bogotá: a step forward in the configuration of the concept of digital citizenship in Colombia. ; Monitoring through ICT of Mobility: technological collaborative feature to incorporate IoT in a Smart City. ; Characterization model of asphalt mixtures using digital image processing. ; Review: identification of diseases and/or pests in fruit trees through image processing techniques and artificial intelligence. ; VRS applicated to Nasa Yuwe language. ; Application of Pix2Pix for edge reconstruction in images. ; Brushless DC Motor Control System for Active Myoelectric Prosthesis. ; Implementation of a Water Conductivity Measuring System. ; 2 DOF robot programmed with MatLab® (guide and Peter Corke) and Arduino uno for writing alphabetical characters. ; Simulator of the behavior of the center of mass in a quadruped robot. ; Biomimetic prototype for flapping movement of batsContent: Contenido: Approach to the diagnostic of cesarean birth using bio-inspired models. ; Design of a tool in a virtual reality environment to manipulate anatomical models. ; The effect of COVID-19 restrictions on the electricity price forecasting models. ; Depression prevention through artificial intelligence. ; State of the art in Prototypes as complements to the learning of the Colombian Sign Language (LSC). ; A computational proposal for gene expression deterministic analysis in associated disorders to depression and anxiety. ; Evaluation of postural stability from the predictability of the measurement of the center of pressure. ; Psychophysiological Analysis of Sound Stimuli.; Delphi method for the identification of relevant variables in the development of low-power photovoltaic solar projects. ; Socioeconomic impact of a refrigerator powered by a photovoltaic system in La Guajira. ; Energy Efficiency: characteristics that allow the reduction of greenhouse gases in. ; Possibilities for the implementation of a bioreactor from organic waste. ; Energy Potential with Small Hydroelectric Power Plants in Non- interconnected Zones of Colombia. ; Energy Potential in Photovoltaic Solar Solutions in Non-Interconnected Areas of Colombia. ; Photovoltaic system, towards the energy transition from home. ; Blockchain model to increase the transparency of public sector processes. ; Intelligent agricultural irrigation prescription system based on sensor networks and crop modeling. ; Design and implementation of a digital modulation classification system using intelligent algorithms. ; A mobile application proposal to minimize intermediation during agricultural process distribution of products in supply chain. ; Accompanying strategy for the social appropriation of new technologies in vulnerable agricultural communities: case in communities producing Gulupas fruits (Passiflora edulis Sims). ; Predictive model of transparency as an indicator of Public Policies. ; Smart system for recognition of ripening level in blackberry fruits. ; Project-based learning as an alternative methodology for technological education in electronics. ; Design and construction of an automated system for N. ; Four bar mechanisms (FBM) and their Software-Based applications: a reviewFT aquaponic culture of Red Carp and Crespa Lettuce. ; Intelligent search implementation for the construction of states of the art: a python application. ; Indoor and Outdoor propagation models on 5G environments: state of the art. ;The electronic detection of offenders (DOO) in the District Secretary of mobility of Bogotá: a step forward in the configuration of the concept of digital citizenship in Colombia. ; Monitoring through ICT of Mobility: technological collaborative feature to incorporate IoT in a Smart City. ; Characterization model of asphalt mixtures using digital image processing. ; Review: identification of diseases and/or pests in fruit trees through image processing techniques and artificial intelligence. ; VRS applicated to Nasa Yuwe language. ; Application of Pix2Pix for edge reconstruction in images. ; Brushless DC Motor Control System for Active Myoelectric Prosthesis. ; Implementation of a Water Conductivity Measuring System. ; 2 DOF robot programmed with MatLab® (guide and Peter Corke) and Arduino uno for writing alphabetical characters. ; Simulator of the behavior of the center of mass in a quadruped robot. ; Biomimetic prototype for flapping movement of bat