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Estudo da curvatura central das placas cerâmicas para revestimentos : a influência da fusibilidade e coeficiente de expansão térmica da camada de engobe nas curvaturas desenvolvidas durante e após a queima
(Universidade Federal de São Carlos, 2017-09-05) Rodrigues, Bruno Caio; Melchiades, Fábio Gomes; https://lattes.cnpq.br/4469106561041487; Boschi, Anselmo Ortega; https://lattes.cnpq.br/3259846931278607; https://lattes.cnpq.br/2656329333127220
Most ceramic tiles have a slip layer and this has a significant influence on the characteristics of the ceramic tiles. In contrast to this reality, the specialized literature on engobes is sparse and superficial. It is known, from experience, that the engobe layer influences the texture of the glazed ceramic tile surface, the curvature of the tiles, the appearance of pathologies such as the water stain, etc. In this context, the objective of the present work was to contribute to a better understanding of the role of the engobe in the ceramic tiles. For this, the influence of the fusibility variation and coefficient of thermal expansion of different engobes on the development of the central curvature of the tiles during and after burning was studied. Four engobes with different coefficients of thermal expansion and different fissures were developed. To determine the fusibility of the engobes, a heating optical microscope was used and a contact dilatometer was used to determine the coefficients of thermal expansion of the engobes and the substrate. In order to evaluate the influence of the differences in the coefficients of thermal expansion and fusibility of the engobes in the development of the central curvature of the tiles the optical fleximeter of heating was used. With the results, it was possible to perceive that the more refractory the engobe in relation to the substrate will be the development of the convex curvature and the more the flux the greater the development of the concave curvature, and the greater the probability of this accompanying the behavior of the substrate until the beginning of the cooling due to the creep mechanism provided by the volume and viscosity of the liquid phases formed during burning. In cooling, the higher the coefficient of thermal expansion of the engobe in relation to the substrate, the greater the development of concave curvature and the smaller the greater the development of the convex curvature.
Estudo do efeito do estresse crônico sobre a função cardiovascular em ratas normotensas e espontaneamente hipertensas (SHR)
(Universidade Federal de São Carlos, 2017-09-05) Vieira, Jonas Oliveira; Crestani, Carlos Cesar; https://lattes.cnpq.br/1117432571971568; https://lattes.cnpq.br/1849706158705351
The aim of the present study was to investigate the physiological and somatic changes, with emphasis on the analysis of effects on cardiovascular function, induced by exposure to chronic stress in normotensive male and female rats. We also investigated the possible vulnerability of spontaneously hypertensive females rats (SHR) to physiological and somatic effects induced by stress protocols. The animals were exposed to 10 days protocols of repeated restraint stress (RRS) and chronic variable stress (CVS) protocols. We observed that control females presented basal HR values higher than males, and this effect was related to higher cardiac sympathetic activity and lower cardiac parasympathetic activity, when compared to males. In addition, both RRS and CVS caused HR increase in males, in which it was related to an increase in cardiac sympathetic activity. However, only RRS increased basal HR in females, in which it was also accompanied by an increase in cardiac sympathetic activity. Both RRS and CVS increased plasma corticosterone levels in females. We observed that both stress protocols decreased body weight gain only in males. In addition, CVS caused adrenal hypertrophy in males. Both RRS and CVS reduced the reflex bradycardia response triggered by increased blood pressure in males. In addition, CVS increased the reflex tachycardiac response triggered by decreases of blood pressure in males. Neither of the chronic stress protocols influenced baroreflex activity in females. Regarding the blood pressure response to vasoactive agents, we observed that the pressor response due to the intravenous administration of phenylephrine was not altered by neither of the chronic stress protocols in both genders. The response of acetylcholine was reduced only by CVS in males and increased by both stress protocols in females. The RRS also increased the SNP response in males, but in females both protocols decreased the response to SNP. As expected, we observed that SHR females had higher baseline blood pressure values than normotensive females. RRS caused an increase in basal heart rate in both normotensive and SHR female rats, in which it was related to an increase in cardiac sympathetic activity. Both chronic stress protocols increased baseline plasma corticosterone levels and reduced body weight gain in both SHR and normotensive females. In addition, CVS and RRS caused hypertrophy of the adrenal glands in normotensive rats and increased thymus weight in SHR rats. In summary, concerning to the influence of sexual dimorphisms, the results indicate that, regardless of the type of stress, males are vulnerable to somatic effects and on body weight, while females appear to be more susceptible to the effects of chronic stress on baseline HPA axis activity. In addition, present findings indicate that females are selectively vulnerable to cardiovascular and autonomic changes evoked by homotypic stressors, whereas homotypic and heterotypic stressors similarly affect cardiovascular function and autonomic activity in males. Regarding an influence of hypertension, the findings did not indicate differences in cardiovascular, somatic and neuroendocrine responses induced by stress protocols in normotensive and SHR female rats.
Efeito do extrato bruto da cianobactéria Radiocystis fernandoi em pacu (Piaractus mesopotamicus, Holmberg, 1887)
(Universidade Federal de São Carlos, 2017-09-05) Tavares, Driele; Fernandes, Marisa Narciso; https://lattes.cnpq.br/3021357484136942; https://lattes.cnpq.br/7521276162651566
Increasing levels of eutrophication in aquatic environments favors the appearance and proliferation of cyanobacteria that can produce toxic compounds and exhibit varying levels of toxicity. Microcystins (MCs) are hepatotoxins that can be produced by different species of cyanobacteria, but which can affect other organs. The objective of the present study was to investigate whether the crude extract of Radiocystis fernandoi strain R28, which contains MC-RR and MC-YR variants and small amounts of other oligopeptides, may present fish toxicity (Piaractus mesopotamicus), compromising the osmoregulatory processes in gills and kidneys, as well as liver function. P. mesopotamicus were injected intraperitoneally (ip) with 100 μg of MC-LR equivalent per kg-1 body weight using 0.5 ml of saline solution (NaCl 0.9%) as vehicle and the gills, kidneys and liver were analyzed 6 and 24 hours after injection using biochemical and morphological biomarkers. The respective controls for each time were i.p. injected with 0.5 mL of saline solution. The gills showed no changes in PP1 and PP2A phosphatase proteins and in the kidneys there was inhibition 6 h after injection. A change in ionic balance occurred. In the gills, Na/K-ATPase (NKA) activity increased after 3 h, decreased after 6 h and did not change after 24 h, the activities of H-ATPase (HA) and carbonic anhydrase (CA) were not altered; there was no change in these enzymes. Chloride cells (CC) decreased 3 h after crude extract injection and showed a tendency to increase in the lamellae after 6 and 24 hours. Several histopathologies such as cell hypertrophy, partial lamella fusion, and lamellar epithelial dislocation and disruption were observed in the gills, but no changes occurred in the kidneys. The histopathological and enzymatic changes in the gills after the injection of crude extract of R. fernandoi and the alteration of Na+plasma show that the substances present in the extract influence the ionic homeostasis in fish. Changes in hepatic and cellular architecture, hyperemia, cellular hypertrophy, cellular atrophy, nuclear alterations and, after 24 hours, the increase of intracellular inclusions together with pycnotic nuclei may be indicative of the inhibition of PP1 and PP2A in the liver of cell death. In addition, alterations in plasma levels of alanine aminotransferases (ALT), aspartate aminotransferases (AST), acid phosphatase (ACP) and alkaline phosphatase (ALP) of liver function as well as changes in bilirubin levels indicate impairment and damage to hepatocyte structure . In conclusion, the results suggest that the crude extract of the R. fernandoi cyanobacteria can compromise the osmoregulatory processes with the alteration of the NKA and chloride cells with consequent alteration in the plasma concentration of ions and present hepatic toxicity compromising the function of the liver and being able to affect the health and survival of fish.