Conceção e ensaio experimental de pilares com capitéis

A presente dissertação tem como objetivo o estudo do comportamento de pilares prismáticos de granito com capitéis nas extremidades, no que se refere às vantagens e desvantagens quando sujeitos a compressão axial. Em [4] foram estudados provetes semelhantes aos do presente estudo, mas sem capitel, tendo-se verificado em ensaios experimentais que a rotura se iniciou quase sempre na secção de aplicação de carga. Com a introdução de um elemento de transição, na zona de aplicação do carregamento, conseguiu-se que essa zona deixasse de ser condicionante para a rotura do provete. Através da recolha bibliográfica efetuada constatou-se que são diversos os casos em que se faz recurso ao capitel como elemento de remate, desempenhando um papel estrutural importante nos pilares, nomeadamente de minas e de pontes, independente dos aspetos estéticos. Através de uma análise numérica foram estudados diversos modelos de capitel, tendo-se chegado a geometrias com maior probabilidade de propiciar melhores resultados experimentais quando o pilar é sujeito a esforços de compressão axial. A realização da análise numérica foi fundamental para excluir a hipótese de ensaio dos modelos menos adequados ao problema em causa. Verificou-se que nos modelos em que a secção de aplicação de carga era maior do que a secção do pilar, ocorreu uma concentração de tensões de compressão na interface pilar-capitel, sendo essa concentração maior nos modelos com capitel paralelepipédico. Também se concluiu que as chapas de aço que ficam em contacto com os topos do provete durante o ensaio experimental devem ter a mesma dimensão do provete, a fim de evitar a concentração de tensões de compressão nas arestas do capitel. O ensaio experimental permitiu, por comparação dos valores de tensão média de rotura dos provetes com capitel com os provetes de referência (sem capitel), verificar que nos provetes em que o capitel possui uma secção de aplicação da carga maior do que a secção do pilar a resistência do provete aumenta. Verificou-se que o grupo de provetes mais resistentes foi o que possuía capitel de faces planas com inclinação de 20%. A análise experimental permitiu concluir que o elemento de transição “capitel” proporciona um aumento da resistência global do provete quando sujeito a forças de compressão axial. Conclui-se ainda que o capitel faz com que a secção de aplicação de carga não seja condicionante no processo de rotura do provete.This thesis aims to study the behavior of prismatic granite columns with capitals in the extremities, when subjected to axial compression. Test samples similar to those of this study were already investigated in [4], but without capital, and it was found in experimental studies that the rupture zone almost always started in the load application section. With the introduction of a transition element in the zone of load application, it was found that those end zones were not conditioning the strength of the specimens. Through a bibliographic review, it was found that there are several cases in which the use of capitals in the top or bottom of columns plays an important structural role, namely in mine and bridge pillars, regardless of aesthetic aspects. Through a numerical analysis, many capital models were studied, aiming to find most favorable geometries for capitals to provide better experimental results when the pillar is subjected to axial compressive forces. The realization of the numerical analysis was essential to exclude the hypothesis of testing models less suitable to the problem. It was found that the models in which the load application section was larger than the section of the pillar, a concentration of compressive stresses occurred at the interface pillar-capital, being this concentration higher in models with parallelepiped capital. It was also found that steel sheets which are in contact with the tops of the capitals during the test must have the same stone size in order to avoid concentration of compressive stresses at the edges of capital. The laboratory tests allowed the comparison of the average strength of specimens with capital and reference specimens (without capital). It could be verified that the breaking load increased for specimens with a load application section greater than the column section. It was found that the group of more resistant specimens was the one of capitals with plane inclined faces with a slope of 20%. Experimental analysis confirmed that the transition element “capital” provides increased overall strength of the columns when subjected to axial compression forces. It could be also conclude that the capital has influence in the rupture modus, in which the load application section is not conditioning the global specimen strength

A fossil in a metamorphic rock! Is it possible, teacher?

RERUMO: Partindo da problematização – Podemos encontrar fósseis em rochas metamórficas? – construiu-se uma aprendizagem baseada na resolução de problemas (ABRP) que pretende desafiar os alunos de “Ciências Naturais” (7.º ano) e de “Biologia e Geologia” (10.º/11.º anos) a utilizarem metodologias de trabalho similares às metodologias de investigação dos cientistas. Selecionaram-se os conteúdos temáticos fósseis e metamorfismo, desenhou-se o cenário geológico, planificaram-se e construíram-se, em formato digital, todos os recursos didático-pedagógicos necessários à implementação da ABRP, nomeadamente: guião do professor; PowerPoint e vídeo de apresentação da ABRP e cenário geológico, e a App “Fósseis em rochas metamórficas”. Os recursos didático-pedagógicos foram validados por especialistas de Geologia e de Educação e disponibilizados na plataforma Google Sites, com a designação “Rochas metamórficas”. Com esta ABRP pretende-se a corresponsabilização pessoal de participação/empenho, a valorização de processos e produtos do trabalho interpares, o desenvolvimento cognitivo, procedimental e afetivo e despertar o interesse dos alunos pelas ciências.ABSTRACT: From the question – Can we find fossils in metamorphic rocks? – problem-based learning (PBL) was implemented, aiming to challenge “Natural Sciences” (7th grade) and “Biology and Geology” (10th/11th grade) students to use methodologies similar to the scientific process. The thematic contents fossils and metamorphism were selected, the geological scenario was designed, and all the didactic and pedagogical resources needed for the implementation of the PBL were planned and constructed in digital format, namely: teacher's guide; PowerPoint and video presentation of the PBL and geological scenario, and the App "Fossils in metamorphic rocks" for the students. The didactic-pedagogical resources were validated by Geology and Education experts and made available on Google Sites platform, entitled "Metamorphic rocks". The purpose of this PBL is the personal co-responsibility of participation/performance, the valorisation of processes and products of peer work, the cognitive, procedural and affective development, and to awaken students' interest in science.info:eu-repo/semantics/publishedVersio

Fossils in metamorphic rocks from Coimbra University’s Krantz collection: historical resource and scientific capital for Geology teaching

RESUMO: Aquisição de coleções geológicas para o Museu de História Natural da Universidade de Coimbra, especialmente incidente no final do século XIX, remonta à reforma pombalina (1772). Após décadas de uso intenso no ensino prático, muitos destes acervos encontram-se nos reservados do museu, incluindo uma extensa coleção de rochas do comptoir alemão Krantz, posterior a 1885. Esta inclui 470 amostras de mão de rochas metamórficas europeias, das quais 34 com fósseis de plantas e invertebrados do paleozoico da Alemanha (19), República Checa (7), Dinamarca (4), entre outros países. Contém pteridófitas (61,8%), graptólitos (23,5%), bivalves (5,9%), crinoides (2,9%), crustáceos (2,9%) e um “falso fóssil”. Este conjunto valoriza a coleção histórica de rochas, relacionando sedimentogénese, fossilização e metamorfismo, conteúdos temáticos dos programas de Ciências Naturais lecionados no ensino básico e secundário de Portugal. No seu todo, constitui um importante capital científico e didático, merecendo valorização e divulgação, particularmente, através da comunicação digital.ABSTRACT: The acquisition of geological collections for the Natural History Museum of the University of Coimbra, particularly incident in the late 19th century, dates back to the pombaline reform (1772). After decades of intense use in practical teaching, many collections are now in the museum reserves, including a large set of metamorphic rocks bought from the German comptoir Krantz, after 1885. It includes 470 hand-samples of European metamorphic rocks, of which 34 with fossils of plants and invertebrates from the Palaeozoic of Germany (19), Czech Republic (7) and Denmark (4), among other countries. It contains pteridophytes (61.8%), graptolites (23.5%), bivalves (5.9%), crinoids (2.9%), crustaceans (2.9%) and a “Pseudofossils”. Its presence values the historical rock collection, relating sedimentogenesis, fossilization and metamorphism, themes of Natural Sciences taught in middle and high school. As a whole, the collection constitutes an important scientific and didactic capital that deserves to be preserved and disseminated, particularly, through digital communication.info:eu-repo/semantics/publishedVersio

Efficacy and safety of sparsentan versus irbesartan in patients with IgA nephropathy (PROTECT): 2-year results from a randomised, active-controlled, phase 3 trial

BackgroundSparsentan, a novel, non-immunosuppressive, single-molecule, dual endothelin angiotensin receptor antagonist, significantly reduced proteinuria versus irbesartan, an angiotensin II receptor blocker, at 36 weeks (primary endpoint) in patients with immunoglobulin A nephropathy in the phase 3 PROTECT trial's previously reported interim analysis. Here, we report kidney function and outcomes over 110 weeks from the double-blind final analysis.MethodsPROTECT, a double-blind, randomised, active-controlled, phase 3 study, was done across 134 clinical practice sites in 18 countries throughout the Americas, Asia, and Europe. Patients aged 18 years or older with biopsy-proven primary IgA nephropathy and proteinuria of at least 1·0 g per day despite maximised renin–angiotensin system inhibition for at least 12 weeks were randomly assigned (1:1) to receive sparsentan (target dose 400 mg oral sparsentan once daily) or irbesartan (target dose 300 mg oral irbesartan once daily) based on a permuted-block randomisation method. The primary endpoint was proteinuria change between treatment groups at 36 weeks. Secondary endpoints included rate of change (slope) of the estimated glomerular filtration rate (eGFR), changes in proteinuria, a composite of kidney failure (confirmed 40% eGFR reduction, end-stage kidney disease, or all-cause mortality), and safety and tolerability up to 110 weeks from randomisation. Secondary efficacy outcomes were assessed in the full analysis set and safety was assessed in the safety set, both of which were defined as all patients who were randomly assigned and received at least one dose of randomly assigned study drug. This trial is registered with ClinicalTrials.gov, NCT03762850.FindingsBetween Dec 20, 2018, and May 26, 2021, 203 patients were randomly assigned to the sparsentan group and 203 to the irbesartan group. One patient from each group did not receive the study drug and was excluded from the efficacy and safety analyses (282 [70%] of 404 included patients were male and 272 [67%] were White) . Patients in the sparsentan group had a slower rate of eGFR decline than those in the irbesartan group. eGFR chronic 2-year slope (weeks 6–110) was −2·7 mL/min per 1·73 m2 per year versus −3·8 mL/min per 1·73 m2 per year (difference 1·1 mL/min per 1·73 m2 per year, 95% CI 0·1 to 2·1; p=0·037); total 2-year slope (day 1–week 110) was −2·9 mL/min per 1·73 m2 per year versus −3·9 mL/min per 1·73 m2 per year (difference 1·0 mL/min per 1·73 m2 per year, 95% CI −0·03 to 1·94; p=0·058). The significant reduction in proteinuria at 36 weeks with sparsentan was maintained throughout the study period; at 110 weeks, proteinuria, as determined by the change from baseline in urine protein-to-creatinine ratio, was 40% lower in the sparsentan group than in the irbesartan group (−42·8%, 95% CI −49·8 to −35·0, with sparsentan versus −4·4%, −15·8 to 8·7, with irbesartan; geometric least-squares mean ratio 0·60, 95% CI 0·50 to 0·72). The composite kidney failure endpoint was reached by 18 (9%) of 202 patients in the sparsentan group versus 26 (13%) of 202 patients in the irbesartan group (relative risk 0·7, 95% CI 0·4 to 1·2). Treatment-emergent adverse events were well balanced between sparsentan and irbesartan, with no new safety signals.InterpretationOver 110 weeks, treatment with sparsentan versus maximally titrated irbesartan in patients with IgA nephropathy resulted in significant reductions in proteinuria and preservation of kidney function

Sparsentan in patients with IgA nephropathy: a prespecified interim analysis from a randomised, double-blind, active-controlled clinical trial

Background: Sparsentan is a novel, non-immunosuppressive, single-molecule, dual endothelin and angiotensin receptor antagonist being examined in an ongoing phase 3 trial in adults with IgA nephropathy. We report the prespecified interim analysis of the primary proteinuria efficacy endpoint, and safety. Methods: PROTECT is an international, randomised, double-blind, active-controlled study, being conducted in 134 clinical practice sites in 18 countries. The study examines sparsentan versus irbesartan in adults (aged ≥18 years) with biopsy-proven IgA nephropathy and proteinuria of 1·0 g/day or higher despite maximised renin-angiotensin system inhibitor treatment for at least 12 weeks. Participants were randomly assigned in a 1:1 ratio to receive sparsentan 400 mg once daily or irbesartan 300 mg once daily, stratified by estimated glomerular filtration rate at screening (30 to 1·75 g/day). The primary efficacy endpoint was change from baseline to week 36 in urine protein-creatinine ratio based on a 24-h urine sample, assessed using mixed model repeated measures. Treatment-emergent adverse events (TEAEs) were safety endpoints. All endpoints were examined in all participants who received at least one dose of randomised treatment. The study is ongoing and is registered with ClinicalTrials.gov, NCT03762850. Findings: Between Dec 20, 2018, and May 26, 2021, 404 participants were randomly assigned to sparsentan (n=202) or irbesartan (n=202) and received treatment. At week 36, the geometric least squares mean percent change from baseline in urine protein-creatinine ratio was statistically significantly greater in the sparsentan group (-49·8%) than the irbesartan group (-15·1%), resulting in a between-group relative reduction of 41% (least squares mean ratio=0·59; 95% CI 0·51-0·69; p<0·0001). TEAEs with sparsentan were similar to irbesartan. There were no cases of severe oedema, heart failure, hepatotoxicity, or oedema-related discontinuations. Bodyweight changes from baseline were not different between the sparsentan and irbesartan groups. Interpretation: Once-daily treatment with sparsentan produced meaningful reduction in proteinuria compared with irbesartan in adults with IgA nephropathy. Safety of sparsentan was similar to irbesartan. Future analyses after completion of the 2-year double-blind period will show whether these beneficial effects translate into a long-term nephroprotective potential of sparsentan. Funding: Travere Therapeutics

Efficacy and safety of sparsentan versus irbesartan in patients with IgA nephropathy (PROTECT): 2-year results from a randomised, active-controlled, phase 3 trial

Background Sparsentan, a novel, non-immunosuppressive, single-molecule, dual endothelin angiotensin receptor antagonist, significantly reduced proteinuria versus irbesartan, an angiotensin II receptor blocker, at 36 weeks (primary endpoint) in patients with immunoglobulin A nephropathy in the phase 3 PROTECT trial's previously reported interim analysis. Here, we report kidney function and outcomes over 110 weeks from the double-blind final analysis. Methods PROTECT, a double-blind, randomised, active-controlled, phase 3 study, was done across 134 clinical practice sites in 18 countries throughout the Americas, Asia, and Europe. Patients aged 18 years or older with biopsy-proven primary IgA nephropathy and proteinuria of at least 1·0 g per day despite maximised renin–angiotensin system inhibition for at least 12 weeks were randomly assigned (1:1) to receive sparsentan (target dose 400 mg oral sparsentan once daily) or irbesartan (target dose 300 mg oral irbesartan once daily) based on a permuted-block randomisation method. The primary endpoint was proteinuria change between treatment groups at 36 weeks. Secondary endpoints included rate of change (slope) of the estimated glomerular filtration rate (eGFR), changes in proteinuria, a composite of kidney failure (confirmed 40% eGFR reduction, end-stage kidney disease, or all-cause mortality), and safety and tolerability up to 110 weeks from randomisation. Secondary efficacy outcomes were assessed in the full analysis set and safety was assessed in the safety set, both of which were defined as all patients who were randomly assigned and received at least one dose of randomly assigned study drug. This trial is registered with ClinicalTrials.gov, NCT03762850. Findings Between Dec 20, 2018, and May 26, 2021, 203 patients were randomly assigned to the sparsentan group and 203 to the irbesartan group. One patient from each group did not receive the study drug and was excluded from the efficacy and safety analyses (282 [70%] of 404 included patients were male and 272 [67%] were White) . Patients in the sparsentan group had a slower rate of eGFR decline than those in the irbesartan group. eGFR chronic 2-year slope (weeks 6–110) was −2·7 mL/min per 1·73 m2 per year versus −3·8 mL/min per 1·73 m2 per year (difference 1·1 mL/min per 1·73 m2 per year, 95% CI 0·1 to 2·1; p=0·037); total 2-year slope (day 1–week 110) was −2·9 mL/min per 1·73 m2 per year versus −3·9 mL/min per 1·73 m2 per year (difference 1·0 mL/min per 1·73 m2 per year, 95% CI −0·03 to 1·94; p=0·058). The significant reduction in proteinuria at 36 weeks with sparsentan was maintained throughout the study period; at 110 weeks, proteinuria, as determined by the change from baseline in urine protein-to-creatinine ratio, was 40% lower in the sparsentan group than in the irbesartan group (−42·8%, 95% CI −49·8 to −35·0, with sparsentan versus −4·4%, −15·8 to 8·7, with irbesartan; geometric least-squares mean ratio 0·60, 95% CI 0·50 to 0·72). The composite kidney failure endpoint was reached by 18 (9%) of 202 patients in the sparsentan group versus 26 (13%) of 202 patients in the irbesartan group (relative risk 0·7, 95% CI 0·4 to 1·2). Treatment-emergent adverse events were well balanced between sparsentan and irbesartan, with no new safety signals. Interpretation Over 110 weeks, treatment with sparsentan versus maximally titrated irbesartan in patients with IgA nephropathy resulted in significant reductions in proteinuria and preservation of kidney function.</p