Authors:Eveline De Robertis, Gabriela F. Moreira, Raigna A. Silva, and Carlos A. Achete
Quality control of fuel-related properties of biodiesel, such as thermal stability, is needed to obtain consistent engine performance by fuel users, since biodiesel is susceptible to auto-oxidation when exposed to air, light, and temperature during storage. In this work two pure standard reference materials of biodiesels produced from soy oil and animal feedstocks were studied. Differential scanning calorimetry and thermogravimetry measurements were performed and the analysis of the results revealed small temperature variations in the thermal events among the two standards, these differences are due mainly to their chemical composition, been highly influenced by the amounts of unsaturated esters.
Authors:Kelly C. Teixeira, Gabriela F. Moreira, Welber G. Quirino, Cristiano Legnani, Raigna A. Silva, Marco Cremona, Hermi F. Brito, and Carlos A. Achete
The improvement of operational lifetime and efficiency of organic light-emitting devices has stimulated many studies focused on the mechanisms responsible for their degradation. Such instabilities can be induced by several factors such as (i) current flow and heating, (ii) chemical reactions, (iii) self-conversion of the charge transporting molecules to cation, anion, and/or radical species. This work aims at investigating the thermal stability of rare-earth based tetrakis beta-diketonates complexes like M[Eu(dbm)4] (M = Li+, TMPip+, and Morf+) through TG technique coupled with FTIR. Preliminary results show that Li[Eu(dbm)4]·4H2O complex presents no degradation in its structure until 300 °C. However, evidences of rapid thermal degradation of the other two compounds have been found at temperatures lower than 100 °C, implying that these complexes could be degraded during the thermal deposition process at relatively high temperatures.
Authors:Igor Rabelo de França, Daniela Meneses-Santos, Gabriela Virginia Moreira, Fábio Bessa Lima, Carla Roberta de Oliveira Carvalho, and Anderson Carlos Marçal
Background and aims
The treatment with glucocorticoids may induce molecular changes in the level and/or degree of phosphorylation of proteins located downstream of the insulin receptor/insulin-like growth factor receptor (IR/IGF1R) in many tissues. However, few studies have investigated the intracellular insulin pathway in the masseter muscle. Therefore, this study aimed to analyze the IR/IGF1R signaling pathway in the masseter muscle of rats treated with dexamethasone.
Materials and methods
Male Wistar rats were divided into two groups: control group (intraperitoneally injected with 0.9% NaCl solution) and dexamethasone group [intraperitoneally injected with 1 mg/kg (bw) dexamethasone solution] for 10 consecutive days. Sections of the masseter muscle were removed at time zero and after the infusion of regular insulin into the portal vein.
Dexamethasone administration induces body weight loss without changing masseter muscle weight and reduces the expression of total IR and PI3K proteins; total levels of IRS1, Akt, and ERK1 remain unchanged between groups. The degree of phosphorylation/activity of IRS1 after insulin stimulus increased only in the control group; degree of phosphorylation of Akt increased in both groups, but this increase was attenuated in the dexamethasone group.
Discussion and conclusion
The degree of phosphorylation/activity in the masseter muscle is different from that in other muscle territories.