Avaliação de argamassas colantes por reometria rotacional

As argamassas colantes são produtos constituídos por areia natural ou artificial, ligantes (cimento) e aditivos químicos que cumprem uma função de adesivo para assentamento de revestimentos em pisos e paredes. Atualmente, a avaliação em campo sobre a mistura do produto é efetuada de forma empírica. O aplicador (pedreiro) determina, por meios de aspectos sensoriais, a facilidade ou a dificuldade de mistura, classificando a argamassa em pesada, leve, macia, de fácil ou de difícil mistura, etc. Porém, essas descrições são subjetivas e é difícil de mensurar quantitativamente a aplicabilidade do produto, além do que induzem a erros de avaliação, pois cada aplicador pode ter uma percepção diferente. O propósito deste trabalho foi medir, através da reometria rotacional, duas composições para avaliar o comportamento de mistura e reológico de forma quantitativa. Foram utilizadas duas argamassas colantes de mercado do tipo ACI (Argamassa Colante do Tipo I) e ACIII (Argamassa Colante do Tipo III), as quais foram submetidas a ensaios de reometria rotacional, variando-se o teor de água. Os resultados desta pesquisa demonstram que o tempo de mistura de 150 s é eficiente e suficiente para homogeneizar e estabilizar as argamassas testadas, e que a argamassa do tipo ACI apresenta maior dificuldade de mistura e resulta em uma suspensão com maior viscosidade e tensão de escoamento do que a argamassa ACIII. Este estudo mostra a aplicação e os resultados inéditos de reometria rotacional para avaliação do comportamento reológico de argamassas colantes. Essa transferência do conhecimento visa ampliar os horizontes sobre os comportamentos dos materiais de construção civil para melhorar o desempenho de aplicação e avaliação da argamassa no estado fresco

Autoantibodies against type I IFNs in patients with critical influenza pneumonia

In an international cohort of 279 patients with hypoxemic influenza pneumonia, we identified 13 patients (4.6%) with autoantibodies neutralizing IFN-alpha and/or -omega, which were previously reported to underlie 15% cases of life-threatening COVID-19 pneumonia and one third of severe adverse reactions to live-attenuated yellow fever vaccine. Autoantibodies neutralizing type I interferons (IFNs) can underlie critical COVID-19 pneumonia and yellow fever vaccine disease. We report here on 13 patients harboring autoantibodies neutralizing IFN-alpha 2 alone (five patients) or with IFN-omega (eight patients) from a cohort of 279 patients (4.7%) aged 6-73 yr with critical influenza pneumonia. Nine and four patients had antibodies neutralizing high and low concentrations, respectively, of IFN-alpha 2, and six and two patients had antibodies neutralizing high and low concentrations, respectively, of IFN-omega. The patients' autoantibodies increased influenza A virus replication in both A549 cells and reconstituted human airway epithelia. The prevalence of these antibodies was significantly higher than that in the general population for patients 70 yr of age (3.1 vs. 4.4%, P = 0.68). The risk of critical influenza was highest in patients with antibodies neutralizing high concentrations of both IFN-alpha 2 and IFN-omega (OR = 11.7, P = 1.3 x 10(-5)), especially those <70 yr old (OR = 139.9, P = 3.1 x 10(-10)). We also identified 10 patients in additional influenza patient cohorts. Autoantibodies neutralizing type I IFNs account for similar to 5% of cases of life-threatening influenza pneumonia in patients <70 yr old

CONCEPTION AND VALIDATION OF A REFLUX LARYNGITIS MODEL INNEWBORN LAMBS

Background: Daily clinical observations and a recent study (D Vermeylen et al., 2004) suggest that reflux laryngitis (RL) is involved in apneas/ bradycardias of the newborn. The aim of this study is to develop and tovalidate a unique RL model in newborn lambs to test the assumption that a RL provokesan increase in apneas/ bradycardias/ desaturations observed within thelaryngeal chemoreflexes induced by the contact of a liquid with the larynx. Methods: A surgical instrumentation was performed on the first day of life, which included the insertion of a transcutaneous esophageal catheter in order to allow instillation of a gastric juice surrogate (HCl +pepsin at pH 2) directly on the larynx. The 2 ml-instillations were made 3 times per day for 6 consecutive days. At day 9-10 laryngeal chemoreflexes were induced during sleep. The larynx was removed at the time of necropsy to grade inflammation by a histological study. Results: Lambs in which a RL was induced (n = 4) presented characteristic signs of RL: cough, weak bleat, reduction in weight gain. Preliminary histological analyses showed a characteristic laryngeal inflammation. Preliminary results showing that apneas and oxygen desaturations seem more prominent in RL lambs than controls provided further validation ofour RL model. Conclusion: The ovine model developed in this study presents theclinical and histological characteristics of RL observed in newborns. Preliminary results suggesting that a RL increases apneas/bradycardias/desaturations when a liquid is in contact with laryngealmucosa in the newborn must be confirmed. Supported by: CIHR, FRSQ, Foundation of stars

Comparison of linear and non-linear heart rate variability indices between preterm infants at their theoretical term age and full term newborns

International audienceHeart rate variability (HRV) enables non-invasive evaluation of cardiac autonomic activity. Preterm infants are known to have altered HRV characteristics that remain even when reaching their term age. Little is known about non-linear HRV measures between full term and preterm babies close to their theoretical full term. In this study, we calculated sample entropy, shape-describing parameters (skewness and kurtosis) and detrended fluctuation analysis coefficients α1 and α2 from RR time series of 16 very preterm babies (37 weeks, “FT group”) infants. Compared to the FT group, smaller values of sample entropy and lower values of α1 were found in the PT group. No difference in α2, kurtosis, or skewness was found. This indicates decrease in overall complexity of HR dynamics in the PT group. When various HRV indices, that included also non-linear indices, were projected to the principal component analysis space obtained from the FT group, a good separation between the PT and FT groups was found. The study was limited by a small sample but the results were in line with literature. The combinations of several HRV parameters can be of interest for future studies on the degree of ANS maturity. © Springer Nature Singapore Pte Ltd. 2018

Esophageal perforation in eosinophilic esophagitis: five cases in children

Background and study aims  Eosinophilic esophagitis (EoE) is a chronic immune disease with increasing incidence. It is clinically defined by symptoms of esophageal dysfunction and histologically by eosinophilic polynuclear cell infiltration of the esophageal mucosa. Symptoms are not specific and include gastroesophageal reflux disease (GERD), dysphagia, vomiting or dietary blockages. Chronic inflammation of the mucosa may lead to narrowing of the esophageal lumen responsible for impactions. Extraction procedures can be complicated by dissection and perforation. Rare spontaneous ruptures of the esophagus known as Boerhaave syndrome are also possible. We report five cases of esophageal perforation in children with EoE, three with spontaneous rupture and two after an endoscopic procedure. The evolution was favorable under medical treatment