DIELECTRIC PROPERTIES OF La/Mn CODOPED BARIUM TITANATE CERAMICS

La/Mn codoped BaTiO3 ceramics with different La2O3 content, ranging from 0.3 to 1.0 at% La, together with undoped BaTiO3,were investigated regarding their microstructure and dielectric properties. The content of MnO2 kept constant at 0.01 at% Mn in all investigated samples. La/Mn codoped and undoped BaTiO3 were obtained by a modified Pechini method and sintered in air at 13000C for two hours.The homogeneous and completely fine-grained microstructure with average grain size from 0.3 to 1mm was observed in samples doped with 0.3 at% La. In high doped samples, apart from the fine grained matrix, the appearance of local area with secondary abnormal grains was observed.The dielectric permittivity and dissipation factor were investigated as a function of frequency and temperature. Dielectric permittivity of doped BaTiO3 was in the range of 3945 to 12846 and decreases with increase of additive content. The highest value of dielectric constant at room temperature (er= 12846) and the greatest change at Curie temperature (er= 17738) were measured in 0.3at% La doped samples. Dissipation factor was range from 0.07 to 0.62 for all investigated samples. The Curie constant (C) and Curie-Weiss temperature (T0) together with critical exponent of nonlinearity (g) were calculated using a Curie-Weiss and modified Curie-Weiss law. The Curie constant increase with increasing dopant content and the highest values were measured in 1.0 La doped samples.  The obtained values of g is in the range from 1.04 to 1.53 and pointed out the sharp phase transformation from ferroelectric to paraelectric phase at Curie temperature

Electrical characteristics of Er doped BaTiO3 ceramics

In this study, the electrical resistivity (ρ) and PTC effect of Er doped BaTiO3 ceramics are investigated. The concentrations of Er2O3 in the doped samples vary from 0.01 to 1.0 at% Er. The samples are prepared by the conventional solid state reaction, and sintered at 1320° and 1350°C in air atmosphere for 4 hours. The SEM analysis shows that all of measured samples are characterized by polygonal grains. The uniform and homogeneous microstructure with grain sizes from 20 to 45μm is the main characteristic of the low doped samples (0.01 and 0.1 at% Er). For the samples doped with the higher dopant concentration (0.5 and 1.0 at%) the average grains sizes have been ranged from 5 to 10 μm. The electrical resistivity is measured in the temperature range from 25°C to 170°C, at frequencies 1 kHz, 10 kHz and 100 kHz. The electrical resistivity values, measured at frequency of 1 kHz and room temperature, have been ranged from 1.62•104 Ωcm to 4.24∙104 Ωcm, for samples sintered at 1320°C and from 1.43•104 Ωcm to 1.94∙104 Ωcm, for samples sintered at 1350°C. A nearly flat and stable electrical resistivity-temperature response is characteristic for all samples at the temperature range from 25°C to 120°C. Above this temperature, the electrical resistivity increases rapidly. At 170°C the value of electrical resistivity is ranged 9.84•104 Ωcm -1.62•105 Ωcm, for Tsin=1320°C, and 6.11•104 Ωcm 1.32•105 Ωcm, for Tsin=1350°C. The electrical resistivity decreases with concentration increment up to 0.5 at%, while above 0.5 at% it increases. Also, with increasing frequency, ρ decreases for a few orders of magnitude. [172057: Directed synthesis, structure and properties of multifunctional materials

Effects of female gonadal hormones and LPS on depressive-like behavior in rats

Considerable evidence shows an association of depression with the immune system and emphasizes the importance of gender in the etiology of the disease and the response to inflammatory stimuli. We examined the influence of immune-challenged systems on depressive-like behavior in female rats in the context of gonadal hormones. We used a neuroinflammatory model of depression elicited by lipopolysaccharide (LPS) administration on naive and ovariectomized (OVX) female rats, and examined the effects of estradiol (E2) and/or progesterone (P4) replacement therapy on animal behavior, as assessed by the forced swimming test (FST). We found that LPS and OVX increase immobility in the FST, while LPS also decreased body weight in naive female rats. Further, even though P4 application alone showed beneficial effects on the behavioral profile (it reduced immobility and increased climbing), supplementation of both hormones (E2 and P4) together to OVX rats failed to do so. When OVX rats were exposed to LPS-induced immune challenge, neither hormone individually nor their combination had any effect on immobility, however, their joint supplementation increased climbing behavior. In conclusion, our study confirmed that both LPS and OVX induced depressive-like behavior in female rats. Furthermore, our results potentiate P4 supplementation in relieving the depressive-like symptomatology in OVX rats, most likely through fine-tuning of different neurotransmitter systems. In the context of an activated immune system, the application of E2 and/or P4 does not provide any advantageous effects on depressive-like behavior

Early onset of abdominal venous thrombosis in a newborn with homozygous type II heparin-binding site antithrombin deficiency

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Genotype phenotype correlation in a pediatric population with antithrombin deficiency

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Distinct modifications of hippocampal glucocorticoid receptor phosphorylation and FKBPs by lipopolysaccharide in depressive female and male rats

Inflammation plays a critical role in pathogenesis of depression and can affect the hypothalamic-pituitary-adrenal axis activity. Accordingly, in this study we investigated the role of hippocampal glucocorticoid receptor in mediating the effects of inflammation on behaviour of female and male Wistar rats. We studied the effects of lipopolysaccharide on the levels of glucocorticoid receptors and its co-chaperones FK506 binding protein 52 and FK506 binding protein 51, the levels of glucocorticoid receptor phospho-isoforms, pGR-232 and pGR-246, and glucocorticoid receptor up-stream kinases. In order to assess transcriptional activity of glucocorticoid receptor, we measured mRNA levels of several glucocorticoid receptor-regulated genes. We demonstrated that lipopolysaccharide induced depressive-like behaviour and elevated serum corticosterone in both sexes. However, it affected glucocorticoid receptor signalling in the nucleus of females and males differently-in females it elevated levels of glucocorticoid receptors, pGR-246 and FK506 binding protein 52, while in males it decreased levels of glucocorticoid receptor, both co-chaperons and pGR-246. Alterations in pGR-246 were associated with alterations of c-Jun N-terminal kinases. Altered nuclear levels of total glucocorticoid receptors and pGR-246 were accompanied by sex-specific reduction in brain-derived neurotrophic factor and cyclooxygenase-2 mRNA and sex-unspecific reduction in the expression of p11 and glucocorticoid receptor genes. These alterations may ultimately affect different glucocorticoid receptor-associated processes involved in depressive-like behaviour in males and females

Accumulation of Cytoplasmic Glucocorticoid Receptor Is Related to Elevation of FKBP5 in Lymphocytes of Depressed Patients

We have previously shown that patients with the major depressive disorder (MDD) exhibited elevated phosphorylation of the lymphocyte glucocorticoid receptor (GR) at serine 226 (S226). Here, we further analyse potential alterations of GR signalization in lymphocytes of MDD patients, i.e. the cytoplasmic/nuclear distribution of GR, levels of FK506-binding protein 5 (FKBP5) and glucocorticoid-induced leucine zipper (GILZ). The FKBP5 acts as an important regulator of GR activation, by decreasing ligand binding and impeding translocation of the receptor to the nucleus, while GILZ mediates glucocorticoid anti-inflammatory effects. Our result showed that the depressed patients had significantly higher GR levels in the cytoplasm compared to controls, which was accompanied by higher FKBP5 levels. Linear regression model demonstrated significantly higher correlation between FKBP5 and cytoplasmic GR than the presence of MDD itself or phosphorylation of nuclear GR at S226. There were no differences in the levels of GILZ isoforms. Therefore, the results suggest that accumulation of the GR in cytoplasm is related to the elevation of FKBP5, adding one more step in understanding altered GR signalling in lymphocytes, and potentially brain tissue, of MDD patients