AVALIAÇÃO DE TENACIDADE À FRATURA DA LIGA ALUMÍNIO 7075-T651 ATRAVÉS DO PARÂMETRO CTOD, PARA IDENTIFICAÇÃO DE APLICAÇÕES DE ALTA RESPONSABILIDADE

Atualmente, a busca pela prevenção de erros vem se demonstrando cada vez mais necessária. Com isso, quando há fabricação de elementos mecânicos com o intuito de suportar situações adversas em serviço deve haver cuidados quanto a tenacidade à fratura da peça. A tenacidade à fratura de um material corresponde a sua capacidade de absorver energia quando submetido a tensões que possam ocasionar sua fratura. A ocorrência de fraturas está ligada a diversos fatores, sendo um dos mais comuns o fenômeno da fadiga. Dentre as propriedades mecânicas analisadas em metais, o valor equivalente a tenacidade torna-se útil para estabelecer um limite de segurança onde não há risco da ocorrência de rupturas. A Mecânica da Fratura fornece métodos para a obtenção desses valores por meio de dois eixos de estudo inseridos em sua área de conhecimento, sendo eles a Mecânica da Fratura Linear Elástica (MFLE) e a Mecânica da Fratura Elasto-plástica (MFEP). O presente projeto tem como objetivo obter e analisar o valor da propriedade mecânica em questão da liga de alumínio 7075 T651 utilizando o parâmetro CTOD, esse parâmetro baseia se na medição do início da propagação da trinca do material, baseado na sua concentração de tensões, cálculo desenvolvido pela MFEP. Após a obtenção das características mecânicas e metalúrgicas do material, são confeccionados os corpos de provas que são submetidos aos ensaios de tração, flexão por três pontos e fadiga respectivamente, cujo os valores fornecidos são utilizados para o desenvolvimento da equação. O arranjo produtivo local (APL) é caracterizado principalmente pela presença de indústrias do ramo metal-mecânico, desenvolver a análise proposta contribui para expandir e aprimorar a qualificação dos materiais utilizados em seus maquinários, aumentando a produtividade e reduzindo a suscetibilidade a ocorrência de falhas e possíveis prejuízos. Devido a pandemia que se instaurou e todos os empecilhos que ela impôs, osensaios bem como a resolução do cálculo do método CTOD, não foram possíveis de se concluírem

ABC-SPH risk score for in-hospital mortality in COVID-19 patients : development, external validation and comparison with other available scores

The majority of available scores to assess mortality risk of coronavirus disease 2019 (COVID-19) patients in the emergency department have high risk of bias. Therefore, this cohort aimed to develop and validate a score at hospital admission for predicting in-hospital mortality in COVID-19 patients and to compare this score with other existing ones. Consecutive patients (≥ 18 years) with confirmed COVID-19 admitted to the participating hospitals were included. Logistic regression analysis was performed to develop a prediction model for in-hospital mortality, based on the 3978 patients admitted between March-July, 2020. The model was validated in the 1054 patients admitted during August-September, as well as in an external cohort of 474 Spanish patients. Median (25-75th percentile) age of the model-derivation cohort was 60 (48-72) years, and in-hospital mortality was 20.3%. The validation cohorts had similar age distribution and in-hospital mortality. Seven significant variables were included in the risk score: age, blood urea nitrogen, number of comorbidities, C-reactive protein, SpO/FiO ratio, platelet count, and heart rate. The model had high discriminatory value (AUROC 0.844, 95% CI 0.829-0.859), which was confirmed in the Brazilian (0.859 [95% CI 0.833-0.885]) and Spanish (0.894 [95% CI 0.870-0.919]) validation cohorts, and displayed better discrimination ability than other existing scores. It is implemented in a freely available online risk calculator (https://abc2sph.com/). An easy-to-use rapid scoring system based on characteristics of COVID-19 patients commonly available at hospital presentation was designed and validated for early stratification of in-hospital mortality risk of patients with COVID-19

ABC₂-SPH risk score for in-hospital mortality in COVID-19 patients

Objectives: The majority of available scores to assess mortality risk of coronavirus disease 2019 (COVID-19) patients in the emergency department have high risk of bias. Therefore, this cohort aimed to develop and validate a score at hospital admission for predicting in-hospital mortality in COVID-19 patients and to compare this score with other existing ones. Methods: Consecutive patients (≥ 18 years) with confirmed COVID-19 admitted to the participating hospitals were included. Logistic regression analysis was performed to develop a prediction model for in-hospital mortality, based on the 3978 patients admitted between March–July, 2020. The model was validated in the 1054 patients admitted during August–September, as well as in an external cohort of 474 Spanish patients. Results: Median (25–75th percentile) age of the model-derivation cohort was 60 (48–72) years, and in-hospital mortality was 20.3%. The validation cohorts had similar age distribution and in-hospital mortality. Seven significant variables were included in the risk score: age, blood urea nitrogen, number of comorbidities, C-reactive protein, SpO2/FiO2 ratio, platelet count, and heart rate. The model had high discriminatory value (AUROC 0.844, 95% CI 0.829–0.859), which was confirmed in the Brazilian (0.859 [95% CI 0.833–0.885]) and Spanish (0.894 [95% CI 0.870–0.919]) validation cohorts, and displayed better discrimination ability than other existing scores. It is implemented in a freely available online risk calculator (https://abc2sph.com/). Conclusions: An easy-to-use rapid scoring system based on characteristics of COVID-19 patients commonly available at hospital presentation was designed and validated for early stratification of in-hospital mortality risk of patients with COVID-19.</p