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Avaliação da anomalia da teoria de nucleação clássica em vidros silicatos
(Universidade Federal de São Carlos, 2021-07-13) Ramírez Acosta, María Helena; Zanotto, Edgar Dutra; https://lattes.cnpq.br/1055167132036400; https://lattes.cnpq.br/7314093467530639
Under some conditions, the Classical Nucleation Theory (CNT) provides a good description of the temperature dependence of the experimental homogeneous nucleation rates in supercooled liquids. Allegedly, however, it strongly overestimates the experimental nucleation rates below the temperature of maximum nucleation (𝑇_max ~ 𝑇_𝑔, glass transition temperature), configuring the so-called nucleation anomaly. This apparent discrepancy has been associated with some hypothesis related to thermodynamic and diffusional parameters. However, a definitive explanation about the origin of this issue is still open, since some of the hypotheses raised cannot explain it, while others are limited to theoretical analysis without experimental verification. In this thesis, we evaluate the alternative hypothesis that the CNT anomaly can be due to an experimental artifact, which leads to the underestimation of the experimental nucleation rates below 𝑇_𝑔. This hypothesis is based on the fact that the CNT is only valid when the analyzed system reaches a stationary regime. To validate or refute this hypothesis, Li2Si2O5, and BaSi2O5 glasses were chosen as model systems. The study was conducted through the implementation of heat treatments above and below the 𝑇_𝑔 of these glasses. In particular, the heat treatments below 𝑇_𝑔 were considerable extended and examined by a steady-state criterion. Also, viscosity and growth rates were used as alternative proxies for the nucleation diffusion coefficient. Additionally, the possible influence on the nucleation rates of factors as the chemical homogeneity, water content, and thermal history of the glasses were evaluated. The results not only validate the proposed hypothesis, but also offer new experimental evidence supporting recent studies that suggest the interdependence between the structural relaxation and the nucleation process, as the fundamental origin of the alleged CNT anomaly.
Epidemiology, biodiversity, and technological trajectories in the Brazilian Amazon: from malaria to Covid-19
(Universidade Federal de São Carlos, 2021-07-13) Codeço, Cláudia Torres; Dal'Asta, Ana Paula; Rorato, Ana Claudia ; Lana, Raquel Martins; Neves, Tatiana Campos; Andreazzi, Cecilia Siliansky de; Barbosa, Milton; Escada, Maria Isabel Sobral; Fernandes, Danilo Araujo; Rodrigues, Danuzia Lima; Reis, Izabel Cristina dos; Silva-Nunes, Mônica da; Gontijo, Alexandre Bahia; Coelho, Flávio Codeço; Monteiro, Antonio Miguel Vieira; https://lattes.cnpq.br/1929576902623348; https://lattes.cnpq.br/9035132783411687; https://lattes.cnpq.br/7344032911778389; https://lattes.cnpq.br/2518752229392005; https://lattes.cnpq.br/1070312160270046; https://lattes.cnpq.br/2839366380149639; https://lattes.cnpq.br/7353853900519992; https://lattes.cnpq.br/5912024067464378; https://lattes.cnpq.br/5180108615629613; https://lattes.cnpq.br/0309050626285266; https://lattes.cnpq.br/8407302694962257; https://lattes.cnpq.br/9947670889009026; https://lattes.cnpq.br/2973777145524104
The Amazon biome is under severe threat due to increasing deforestation rates and loss of biodiversity and ecosystem services while sustaining a high burden of neglected tropical diseases. Approximately two thirds of this biome are located within Brazilian territory. There, socio-economic and environmental landscape transformations are linked to the regional agrarian economy dynamics, which has developed into six techno-productive trajectories (TTs). These TTs are the product of the historical interaction between Peasant and Farmer and Rancher practices, technologies and rationalities. This article investigates the distribution of the dominant Brazilian Amazon TTs and their association with environmental degradation and vulnerability to neglected tropical diseases. The goal is to provide a framework for the joint debate of the local economic, environmental and health dimensions. We calculated the dominant TT for each municipality in 2017. Peasant trajectories (TT1, TT2, and TT3) are dominant in ca. fifty percent of the Amazon territory, mostly concentrated in areas covered by continuous forest where malaria is an important morbidity and mortality cause. Cattle raising trajectories are associated with higher deforestation rates. Meanwhile, Farmer and Rancher economies are becoming dominant trajectories, comprising large scale cattle and grain production. These trajectories are associated with rapid biodiversity loss and a high prevalence of neglected tropical diseases, such as leishmaniasis, Aedes-borne diseases and Chagas disease. Overall, these results defy simplistic views that the dominant development trajectory for the Amazon will optimize economic, health and environmental indicators. This approach lays the groundwork for a more integrated narrative consistent with the economic history of the Brazilian Amazon