Modeling and simulation of an industrial adsorption process of dehydration of natural gas in 4A molecular sieves: Effect of adsorbent aging

Adsorption in molecular sieves is the number one choice for the dehydration of natural gas in offshore platforms. Many phenomenological and mathematical approaches have been used to describe this unit operation. However, the effect of aging on the operation performance, and consequently the adequacy of these models to describe operational field conditions, has been seldom assessed. This work presents the simulation of an industrial unit of natural gas dehydration with 4A molecular sieves in different cycle numbers using a phenomenological model. First, the most adequate equilibrium isotherm to describe experimental data of pure compound adsorption (viz., the dual-site Langmuir isotherm) was determined. Second, momentum, mass, and energy transfer equations were implemented, and the modeling of literature adsorption data was used to verify the adequacy of the developed equations. Finally, an industrial dehydration unit was modeled using the same approach, and calculated breakthrough times were compared to field data. In conclusion, the premature aging of molecular sieves in industrial operation appears as a defining factor in equipment performance

Alternativas tecnológicas para la elaboración y la conservación de productos panificados

329 págs.-- 1ª ed.-- Córdoba (Argentina): Universidad Nacional de Córdoba, 2009.Índice: 1. Masas congeladas / Pablo Daniel Ribotta, Pedro de Alcântara Pessoa Filho, Carmen Cecilia Tadini.- 2. Productos precocidos congelados y refrigerados / Cristina Molina Rosell, Concha Collar.- 3. Utilización de microondas en panificación / Manuel Gómez Pallarés, Bonastre Oliete Mayorga.- 4. Elaboración de productos de panificación especialmente formulados / Manuel Gómez Pallarés, Carmen Cecilia Tadini, Gabriela Teresa Pérez.- 5. Procesos alternativos de nixtamalización del maíz y productos derivados / Eduardo San Martín–Martínez, Ruth Pedroza–Islas, Dora Luz Villagómez–Zavala, Fernando Martínez-Bustos.- 6. Procesos de obtencion de harina de maíz no–nixtamalizada y sus usos / Elevina Pérez Sira, Lilliam Sívoli, Romel Guzmán.- 7. Efecto de la formulación sobre la conservación de los productos de panificación / Concha Collar, Alberto Edel León, Cristina Molina Rosell.- 8. Materiales de envases y sistemas de envasado de productos de panificación / Abel Guarda, María José Galotto, Márcia Arocha Gularte.- 9. Aplicación de biopolímeros formadores de película en productos de panificación / Jesus Alberto Quezada Gallo, Rubén Moreno Terrazas Casildo, Ruth Pedroza Islas, Patricia Lappe–Oliveras.El pan es un alimento que se consume desde épocas remotas y que forma parte de la dieta tradicional de una vasta población localizada en América, Europa, Medio Oriente e India. Su formulación incluye tres componentes básicos: harina, agua y sal. La harina de trigo es la más utilizada, aunque también se emplean harinas provenientes de otros cereales como maíz, arroz, cebada y centeno. Con el correr del tiempo y en las diferentes regiones se han ido introduciendo en esta formulación diversos componentes y formas de procesamiento, lo que ha dado origen a un sinnúmero de productos.Dichos productos responden a las exigencias del consumidor, las que han ido variando con el correr del tiempo. Desde hace ya varios años no sólo se reclaman adecuadas propiedades nutricionales sino que se exigen alimentos de alta calidad, mínimamente procesados, libres de aditivos, seguros desde el punto de vista microbiológico y que posean beneficios para la salud.Los adelantos producidos en la Ciencia y la Tecnología de Alimentos han facilitado el paulatino conocimiento de un sistema sumamente complejo como es la matriz panaria. Esto ha permitido mejorar las propiedades y calidad del pan, a la vez que la introdución en forma paralela de nuevos equipos y tecnología de procesamiento han conducido a la obtención de nuevos productos.Este libro es producto de la Acción 106AC0301 – "Obtención de productos de panificación para necesidades específicas" – PANXTODOS, la cual es patrocinada por el Programa Iberoamericano de Ciencia y Tecnología para el Desarrollo (CYTED).Peer reviewe

Risk of adverse outcomes in offspring with RT-PCR confirmed prenatal Zika virus exposure: an individual participant data meta-analysis of 13 cohorts in the Zika Brazilian Cohorts ConsortiumResearch in context

Summary: Background: Knowledge regarding the risks associated with Zika virus (ZIKV) infections in pregnancy has relied on individual studies with relatively small sample sizes and variable risk estimates of adverse outcomes, or on surveillance or routinely collected data. Using data from the Zika Brazilian Cohorts Consortium, this study aims, to estimate the risk of adverse outcomes among offspring of women with RT-PCR-confirmed ZIKV infection during pregnancy and to explore heterogeneity between studies. Methods: We performed an individual participant data meta-analysis of the offspring of 1548 pregnant women from 13 studies, using one and two-stage meta-analyses to estimate the absolute risks. Findings: Of the 1548 ZIKV-exposed pregnancies, the risk of miscarriage was 0.9%, while the risk of stillbirth was 0.3%. Among the pregnancies with liveborn children, the risk of prematurity was 10,5%, the risk of low birth weight was 7.7, and the risk of small for gestational age (SGA) was 16.2%. For other abnormalities, the absolute risks were: 2.6% for microcephaly at birth or first evaluation, 4.0% for microcephaly at any time during follow-up, 7.9% for neuroimaging abnormalities, 18.7% for functional neurological abnormalities, 4.0% for ophthalmic abnormalities, 6.4% for auditory abnormalities, 0.6% for arthrogryposis, and 1.5% for dysphagia. This risk was similar in all sites studied and in different socioeconomic conditions, indicating that there are not likely to be other factors modifying this association. Interpretation: This study based on prospectively collected data generates the most robust evidence to date on the risks of congenital ZIKV infections over the early life course. Overall, approximately one-third of liveborn children with prenatal ZIKV exposure presented with at least one abnormality compatible with congenital infection, while the risk to present with at least two abnormalities in combination was less than 1.0%. Funding: National Council for Scientific and Technological Development - Brazil (Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq); Wellcome Trust and the United Kingdom's Department for International Development; European Union's Horizon 2020 research and innovation program; Medical Research Council on behalf of the Newton Fund and Wellcome Trust; National Institutes of Health/National Institute of Allergy and Infectious Diseases; Foundation Christophe et Rodolphe Mérieux; Coordination for the improvement of Higher Education Personnel (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Capes); Ministry of Health of Brazil; Brazilian Department of Science and Technology; Foundation of Research Support of the State of São Paulo (Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP); Foundation of Research Support of the State of Rio de Janeiro (Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro – FAPERJ); Foundation of Support for Research and Scientific and Technological Development of Maranhão; Evandro Chagas Institute/Brazilian Ministry of Health (Instituto Evandro Chagas/Ministério da Saúde); Foundation of Research Support of the State of Goiás (Fundação de Amparo à Pesquisa do Estado de Goiás – FAPEG); Foundation of Research Support of the State of Rio Grande do Sul (Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul – FAPERGS); Foundation to Support Teaching, Research and Assistance at Hospital das Clínicas, Faculty of Medicine of Ribeirão Preto (Fundação de Apoio ao Ensino, Pesquisa e Assistência do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto); São Paulo State Department of Health (Secretaria de Saúde do Estado de São Paulo); Support Foundation of Pernambuco Science and Technology (Fundação de Amparo à Ciência e Tecnologia de Pernambuco – FACEPE)