Efectividad de las puzolanas naturales para reducir la expansión álcali-agregado

En esta investigación se caracterizaron tres diferentes materiales puzolánicos naturales de origen ígneo. Se investigó la relación existente entre las características físico-químicas particulares de cada material y su capacidad para disminuir la expansión deletérea producida por la reacción álcali-agregado. Para determinar la efectividad en la reducción de la expansión, se fabricaron barras de morteros que contenían agregado reactivo y, como material cementante, cemento portland ordinario y puzolana natural. Las barras se sometieron a condiciones extremas de exposición y se midieron sus cambios longitudinales producto de la reacción expansiva. Los resultados indican que las puzolanas naturales reducen en más de 40% la expansión de la reacción álcali-agregado en relación a morteros que sólo contiene cemento portland ordinario como material cementante

Propiedades de pastas de cementos modificados con residuos industriales

Pastas fueron elaboradas reemplazando cemento portland ordinario por caliza de bagazo de agave, ceniza volante, nano-SiO2 geotérmica y humo de sílice. Las pastas fueron curadas a 20ºC y 100% de humedad hasta 28 días. Se les evaluó la resistencia a la compresión, resistencia a la penetración de iones cloruro, porosidad y microestructura. Tras la evaluación, los resultados revelaron que las pastas reemplazadas mostraron una matriz más compacta y menos porosa, valores de resistencia a la compresión de hasta un 45% más, valores de paso de carga de hasta 57% menos, en comparación con las pastas de referencia

Effect of the Microstructures Formed in Cements Modified by Limestone Agave Bagasse Ash, Fly Ash, Geothermal Nano-SiO2 Waste and Silica Fume on Chloride Ion Penetration Resistance

In the present work, pastes were fabricated replacing the ordinary portland cement (OPC) by 0, 1.67, 2.5 and 5 wt% of limestone from agave bagasse ash (ABA), fly ash (FA), geothermal nano-SiO2 waste (GNW) and silica fume (SF), using 1.5 wt% of superplasticizer based in carboxylate and a water/binder ratio of 0.45. After fabrication, the pastes were cured at 20ºC and a humidity content of 100% for up to 28 days. The compressive strength, chloride penetration, porosity and microstructural evolution properties were evaluated. The results obtained from the test suggests that the mechanical, electrochemical, physical and microstructural properties resulting from the cured specimens were enhanced, when compared to the cements obtained with pastes composed by 100% of OPC. It was found that the ABA pastes improved by ~15% to ~25% their mechanical resistance, compared with the values obtained for 100% OPC and 5% FA respectively. Additionally, the pastes containing 2.5% of ABA and 2.5% of GNW, showed an increase of 35% in the values of mechanical resistance in comparison to the 100% OPC. It is also worth mentioning that a the pastes experienced a higher densification value, mainly due to the addition of GNW, which promotes the development of a matrix with reduced porosity when compared with values measured at 100% OPC. The chlorine ion penetration ratio had also low values giving an ion penetration resistance around 57 % less. These results revealed that geothermal nano-SiO2 waste (GNW) and limestone of agave bagasse ash (ABA) could be considered as a potentially suitable material for making pastes, mortars and concrete for industrial applications, which will contribute positively to the reduction of the CO2 emissions into the atmosphere, as well as decrease the environmental impact generated at the disposal zones

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study

Background: In 2020, ACIE Appy study showed that COVID-19 pandemic heavily affected the management of patients with acute appendicitis (AA) worldwide, with an increased rate of non-operative management (NOM) strategies and a trend toward open surgery due to concern of virus transmission by laparoscopy and controversial recommendations on this issue. The aim of this study was to survey again the same group of surgeons to assess if any difference in management attitudes of AA had occurred in the later stages of the outbreak. Methods: From August 15 to September 30, 2021, an online questionnaire was sent to all 709 participants of the ACIE Appy study. The questionnaire included questions on personal protective equipment (PPE), local policies and screening for SARS-CoV-2 infection, NOM, surgical approach and disease presentations in 2021. The results were compared with the results from the previous study. Results: A total of 476 answers were collected (response rate 67.1%). Screening policies were significatively improved with most patients screened regardless of symptoms (89.5% vs. 37.4%) with PCR and antigenic test as the preferred test (74.1% vs. 26.3%). More patients tested positive before surgery and commercial systems were the preferred ones to filter smoke plumes during laparoscopy. Laparoscopic appendicectomy was the first option in the treatment of AA, with a declined use of NOM. Conclusion: Management of AA has improved in the last waves of pandemic. Increased evidence regarding SARS-COV-2 infection along with a timely healthcare systems response has been translated into tailored attitudes and a better care for patients with AA worldwide

Technique d'extraction électrochimique des chlorures (contribution a la connaissance de son domaine d'efficacité)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Réalcalinisation électrochimique des bétons armés carbonatés (une alternative de prévention contre la corrosion)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Anales de Edafología y Agrobiología Tomo 43 Número 3-4

Suelos. Variación de la penetrabilidad en suelos del ·altiplano de Pasto, Colombia, por Luis Guevara, B.; Hernan Rojas, G. y Lucio Legarda, B.-- Adsorción de diazinon por montmorillonita. l.-Efecto del Catión de cambio, por G. Dios Cancela, S. González García y M. Martín Aguilar.—.Adsorción de diazinon por montmorillonita. H.-Efecto del pretratamiento térmico de las muestras, por S. González García, G. Dios Cancela y M. Martín Aguilar.-- Síntesis y caracterización de sustancias húmicas a partir de una novolaca y una resina hidroquinona-formaldehido. l.-Bases y síntesis, por Octavio Carpena Artes, Vicente Galvan Fernández y José Luis Valdés Fernández.-- Síntesis y caracterización de sustancias húmicas a partir de una novolaca y una resina hidroquinona-formaldehido. II. Caracterización, por Octavio Carpena Artes, Vicente Galuán López y José Luis Valdés Fernández.-- Influencia del factor antrópico en la evolución de los suelos desarrollados sobre cuarcitas en el clima xérico, por García Fernández, l. y Simón Torres, M.-- Estudio cinético de la actividad fosfatásica en unidades reales y estructurales de agregación del suelo, por Rojo Cámara, M. a J., Busto Núñez, Ma D. y González Carcedo, S.-- Optimización de un método para la determinación de la actividad asparraginásica en muestras de suelo, por García Melus, M. a C. y González, S.-- Modulación microbiana de la ureasa en suelos, por González Carcedo, S. y Fuente Marcos, M. A.-- Distribución de la actividad ureásica en las unidades de estructura del suelo. I. Efecto del fraccionamiento, por Pérez Mateos, M. y González Carcedo, S.-- Estudio genético de suelos del Puerto del Pon ton (León), por Hoyos de Castro, A.; Hernando Massanet, I.: Palomar Ga Villamil y M. L. Gómez Gomez, A.-- Caracterización y génesis de los suelos sobre esquistos de las Marinas (La Coruña), por B. M. Silua Hermo; E. García-Rodeja, Gayoso; F. Macias Vázquez.-- Estudio de ácidos húmicos de tipo P. Distribución de los pigmentos verdes en las diferentes fracciones húmicas del suelo, por Almendros, G. y Dorado, E.—Fertilidad del Suelo. Efecto de la Acidez del suelo sobre el crecimiento y nutrición del trebol violeta en el año siguiente al de la siembra, por J. Arines y R. Fábregas.-- Aplicación del análisis en componentes principales al estudio de las aguas de riego de la Vega Alta del Segura, por Bolarín, M. C.; Muñoz, F.; Romero, M. y Guillen, M. G.—Nutrición y Fisilogía Vegetal. Morfogénesis en secciones de plántulas de castaño cultivadas "in vitro" por San José, M. C. y Vieitez, E.-- Solubilización de los fosfatos BI y tricálcico por Bacillus Cereus. Ensayos "in vitro", por Fernández Herrera, M. Carpena Artes, O. y Cadahía López, C.-- Variación de la relación H/T en el trevol violeta, por Arines, J. Fábregas, R. y Sainz, M.O. Jesús.-- Análisis de la medida de la actividad nitrogenasa (Reducción de Acetileno) para la selección de razas efectivas de Rhizobium, por Eulogio J. Bedmar, Eustoquio Martínez-Molina y José Olivares.-- Dinámica, equilibrios o índices de .los macro y micronutrientes en plantas de Tilia Platypi)yllos Scop., por M. Guzmán y L. Romero.—Ecología. Micorrizas vesículo-arbusculares en praderas de Galicia, por Ma Jesús Sainz; R. Fábregas y J. Arines.—Trabajos recapitulativos. Avances recientes en el estudio de la micorrizas V-A. l.-Formación, funcionamiento y efectos en nutrición vegetal, por J. M. Barea, C. Azcón-Aguilar y B. Roldán-Fajardo.-- Notas.-- BibliografíaPeer reviewe

Evolving trends in the management of acute appendicitis during COVID-19 waves. The ACIE appy II study (vol 46, pg 2021, 2022)

N/

Global attitudes in the management of acute appendicitis during COVID-19 pandemic: ACIE Appy Study

Background: Surgical strategies are being adapted to face the COVID-19 pandemic. Recommendations on the management of acute appendicitis have been based on expert opinion, but very little evidence is available. This study addressed that dearth with a snapshot of worldwide approaches to appendicitis. Methods: The Association of Italian Surgeons in Europe designed an online survey to assess the current attitude of surgeons globally regarding the management of patients with acute appendicitis during the pandemic. Questions were divided into baseline information, hospital organization and screening, personal protective equipment, management and surgical approach, and patient presentation before versus during the pandemic. Results: Of 744 answers, 709 (from 66 countries) were complete and were included in the analysis. Most hospitals were treating both patients with and those without COVID. There was variation in screening indications and modality used, with chest X-ray plus molecular testing (PCR) being the commonest (19\ub78 per cent). Conservative management of complicated and uncomplicated appendicitis was used by 6\ub76 and 2\ub74 per cent respectively before, but 23\ub77 and 5\ub73 per cent, during the pandemic (both P < 0\ub7001). One-third changed their approach from laparoscopic to open surgery owing to the popular (but evidence-lacking) advice from expert groups during the initial phase of the pandemic. No agreement on how to filter surgical smoke plume during laparoscopy was identified. There was an overall reduction in the number of patients admitted with appendicitis and one-third felt that patients who did present had more severe appendicitis than they usually observe. Conclusion: Conservative management of mild appendicitis has been possible during the pandemic. The fact that some surgeons switched to open appendicectomy may reflect the poor guidelines that emanated in the early phase of SARS-CoV-2