Alumina-yttrium aluminum garnet (YAG)-zirconia composites are often produced by the melt solidification method. In the present study, we investigated the fabrication of α-Al2O3/Y3Al5O12 (YAG)/ZrO2 ...composite by Spark Plasma Sintering (SPS) of powders synthesized by Pechini’s sol-gel method. The ternary composites with homogenous microstructure and high density were produced by SPS at 1300 °C for 15 min. The addition of ZrO2 promoted the sintering of composites, resulting in a higher density and, in turn, higher hardness. A change in the indentation fracture behavior as the result of ZrO2 addition was observed.
The preparation of binary aluminate glass microspheres by flame synthesis of powder precursors, and their subsequent sintering under mechanical pressure in a viscous flow regime and in the ...temperature interval between the glass transition temperature Tg and the onset of crystallisation temperature Tx was investigated. The flame synthesis yielded microspheres with diameters between 10 and 40 micron: seven compositions in the pseudo binary system Al2O3-Y3Al5O12 (YAG) were prepared. Except for the eutectic composition, all other compositions were partially crystalline, consisting of amorphous yttrium aluminate matrix containing YAG and alpha-Al2O3 as the main crystalline phases. The presence of crystalline phases was due to insufficient melting of the precursor powder in the flame and could be partially eliminated by re-melting. The results of DTA indicated a tendency of the prepared glasses to crystallisation, with a narrow interval of 50 C between the Tg and Tx. The sintering of microspheres under applied mechanical pressure of 30 MPa resulted in white non-transparent glasses with residual porosity P = 0.12, and increased content of crystalline phases as the result of secondary crystallisation of glasses during sintering. 7 refs.
The Bi and Ni-doped gehlenite glasses were prepared by flame synthesis. The concentration of Bi and Ni was 0.0, 0.5 and 3.0 mol. %. Scanning electron microscopy (SEM) confirmed that spherical ...particles which did not contain any formations indicating the presence of crystalline phases were prepared by the flame synthesis. The amorphous nature of the prepared systems was also confirmed by the results of X-ray diffraction analysis. Both the Ni and Bi-doped gehlenite glass microspheres exhibited complex magnetic properties.
Bi-doped calcium aluminosilicate glass materials (CAS), with the concentration of Bi 3+ ions 0.5, 1.0 and 3.0 mol %, were prepared by conventional melting. The basic properties and thermal behavior ...were studied by X-ray diffraction (XRD), He-pycnometry, X_Ray Fluorescence (XRF) and differential thermal analysis (DTA). XRD analysis showed the presence of crystalline gehlenite traces in samples with the highest Bi content. Crystallization of gehlenite in all prepared samples and crystallization of Bi 2 O 3 in case of samples with 1 and 3 mol.% Bi 3+ content was observed by a combination of DTA and XRD analysis. The increasing ability to crystallize was correlated with the increasing Bi content in the samples.
Undoped and Ni-doped gehlenite glass microspheres were prepared by a combination of solid-state reaction followed by the flame synthesis in methane-oxygen flame. The prepared glass microspheres were ...characterized from the point of view of surface morphology, phase composition, and magnetic properties by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Quantum Design SQUID magnetometer. The prepared glass microspheres were X-ray amorphous. The amorphous character of glass microspheres was further verified by SEM microscopy. The undoped and Ni-doped gehlenite glass microspheres show a complex magnetic behaviour that is a function of the temperature, the magnetic field, and concentration of Ni 2+ ions.
Sea buckthorn (Hippophae rhamnoides L.) is described by various beneficial effects as it contains several bioactive substances characterized by antioxidant effects. These effects are closely related ...to the reduction of oxidative stress that is involved in the development of the disease. One such diseases is Diabetes mellitus, the prevalence of which is growing and is associated primarily with diet, lack of exercise and/or genetics. This study intends to examine the effects of sea buckthorn and metformin on body weight, water and feed intake, glycaemia, insulinemia, sorbitol accumulation and cataract development in Zucker diabetic fatty rats, which represent an animal model of type 2 Diabetes mellitus, as well as to characterize the individual content of bioactive substances and the antioxidant activity of sea buckthorn. Particular concentrations were applied (500 and 1000 mg.kg−1 body weight of sea buckthorn, and combinations with 150 mg.kg−1 body weight of metformin) by gastric gavage. The total antioxidant capacity and bioactive compounds were determined by spectrophotometric analysis. The best results of the study showed suppression of hyperglycaemia, water intake, decreased sorbitol levels in the lens of the eyes after sea buckthorn treatment. Determination of bioactive compounds showed significantly higher values in dry berries when compared to fresh berries of sea buckthorn and high total antioxidant capacity. Our results represent an interest in sea buckthorn and its potential use in the treatment of Diabetes mellitus as well as other experimental studies.
•Sea buckthorn has a positive effect diabetic symptoms in ZDF rats.•ZDF rats are suitable animal model to investigate diabetic complications.•Sea buckthorn affected glucose, insulin, water intake and sorbitol levels.•Sea buckthorn is a rich source of bioactive substances with increased antioxidant activity.
Cornelian cherry (Cornus mas L.) was in the past frequently used in Slovak Republic; meanwhile fell into oblivion despite the fact that it is known as antidiabetic supplement. However, there is no ...research investigated its effect on animal model of Diabetes mellitus (DM) 2 type as it is Zucker diabetic fatty (ZDF) rats. Thus, the aim of this study was to determine the effect of C. mas fruit given orally on the development of DM symptoms in ZDF rats. In the experiment male ZDF rats (fa/fa) and their age-matched non-diabetic lean controls (fa/+) were used aged 12 weeks. Male ZDF rats were administered C. mas in two doses (500 and 1000 mg/kg body weight) using a gastric gavage for 10 weeks. One group of diabetic animals served as positive control and received only distilled water. We found significant decrease of glucose level after oral administration of C. mas in dose of 1000 mg/kg bw in pre-diabetic state of animals (until 7th week of the experiment) and significant restriction of water intake in both C. mas groups against the diabetic control. We presume that the higher dose of Cornelian cherry could be beneficial and helpful in prevention of diabetic symptoms when consumed regularly in young animals.
•Cornelian cherry (Cornus mas L.) was traditional plant used in Slovak Republic,•C. mas given regularly was capable to temporally improve the typical symptoms of diabetes in young animals,•the higher dose of C. mas could be beneficial and helpful in prevention of diabetic symptoms.
Targeting long-term diabetic complications, as well as inflammatory pathologies, aldose reductase inhibitors (ARIs) have been gaining attention over the years. In the present work, in order to ...address the poor membrane permeation of previously reported ARIs, derivatives of N-phenylpyrrole, bearing groups with putative pKa⩾7.4, were synthesized and evaluated for aldose reductase inhibitory activity. The 2-fluorophenol group proved the most promising moiety, and further modifications were explored. The most active compound (31), identified as a submicromolar inhibitor (IC50=0.443μM), was also selective against the homologous enzyme aldehyde reductase. Cross-docking revealed that 31 displays a peculiar interaction network that may be responsible for high affinity. Physicochemical profiling of 31 showed a pKa of 7.64, rendering it less than 50% ionized in the physiological pH range, with potentially favorable membrane permeation. The latter was supported from the successful inhibition of sorbitol formation in rat lenses and the ability to permeate rat jejunum.
