1,238 research outputs found
The correlation of processes of crystallization and changes of free electron density amorphous alloy powder Co80Ni20
Great attention is being given today to investigations on the capabilities and structural changes of amorphous and nanocrystal materials. Structural changes of the amorphous cobalt and nickel alloy powder obtained by electrochemical deposition were investigated in this paper. The crystallization process, as determined by the DSC method, occurred in two steps. The temperature dependence of electrical resistively and magnetic susceptibility in isothermal and non-isothermal conditions within the temperature range of room temperature to 700ºC was determined for the powder samples pressed under pressure of 800 MPa. The X-ray structural examinations results correlate with those of the DSC analysis and the electrical resistively measuring
A study of the low-lying singlet and triplet electronic states of chlorophyll A and B
Chlorophylls have been extensively investigated both experimentally and
theoretically owing to the fact that they are essential for photosynthesis.
We have studied two forms of chlorophyll, chlorophyll a and chlorophyll b, by
means of density functional theory. Optimization of S0, S1 and T1 states was
performed with the B3-LYP functional. The computed fluorescence lifetimes
show good agreement with the available experimental data. The electronic
adiabatic energies of S1 and T1 states are 2.09/2.12 and 1.19/1.29 eV for
chlorophyll a and chlorophyll b respectively. We discussed the implications
of this results on the triplet formation. Also, the calculated vertical
ionization potentials shows good agreement with the experimental results.
[Projekat Ministarstva nauke Reoublike Srbije, br. 172040
Isothermal sintering of BZT ceramics
Starting mixtures of BaCO3 •ZnO and Ti02 were mechanically activated for 0,5, 10,20.40 and 80 minutes in a planetary ball mill. The powders obtained were sintered isothermally to temperatures between 1000 and 1300 °C. The phase composition of powders and sintered samples were followed by X-ray analyses. Also, the changes in microstructures were detected using SEM
Modification of the structural and optical properties of commercial ZnO powder by mechanical activation
Mechanical activation was used as a method for modification of the structural and optical properties of commercial ZnO powder. For this purpose zinc oxide powder was mechanically treated by grinding in a high-energy vibro-mill in a continual regime in air up to 300 minutes. Starting and modified ZnO samples were characterized using XRD, BET and TEM measurements. Optical properties of these samples were investigated by Raman and photoluminescence (PL) spectroscopy. The color of commercial ZnO powder was white while mechanically activated ZnO powder was dark yellow, indicating the presence of nonstoichiometry. In the Raman spectra of non-activated sample Raman modes of bulk ZnO were observed, while the spectra of modified samples point out structural and stoichiometric changes. The PL spectra of modified samples excited by 325 and 442 nm lines of a He-Cd laser show great difference with respect to the spectra of the original sample. This study confirms that change in the defect structure of the ZnO crystal lattice introduced by mechanical activation affects the optical properties of this material
A phenomenological analysis of sintering kinetics from the viewpoint of activated volume
The sintering kinetics of real systems has been viewed as a process of transport of activated volume. Activated volume is a parameter that can be used to describe mass transport during the sintering process. It defines the movement of point defects and dislocations during the sintering process. A phenomenological equation has been defined using this parameter, which can be applied to analyze kinetics of the sintering process. It has been applied to analyze the sintering process of several disperse systems. Values obtained for parameters of the equation have also been analyzed
Crosstalk between dietary patterns, obesity and nonalcoholic fatty liver disease
The prevalence of nonalcoholic fatty liver disease (NAFLD) is rising worldwide, paralleling the epidemic of obesity. The liver is a key organ for the metabolism of proteins, fats and carbohydrates. Various types of fats and carbohydrates in isocaloric diets differently influence fat accumulation in the liver parenchyma. Therefore, nutrition can manage hepatic and cardiometabolic complications of NAFLD. Even moderately reduced caloric intake, which leads to a weight loss of 5%-10% of initial body weight, is effective in improving liver steatosis and surrogate markers of liver disease status. Among dietary patterns, the Mediterranean diet mostly prevents the onset of NAFLD. Furthermore, this diet is also the most recommended for the treatment of NAFLD patients. However, clinical trials based on the dietary interventions in NAFLD patients are sparse. Since there are only a few studies examining dietary interventions in clinically advanced stages of NAFLD, such as active and fibrotic steatohepatitis, the optimal diet for patients in these stages of the disease must still be determined. In this narrative review, we aimed to critically summarize the associations between different dietary patterns, obesity and prevention/risk for NAFLD, to describe specific dietary interventions’ impacts on liver steatosis in adults with NAFLD and to provide an updated overview of dietary recommendations that clinicians potentially need to apply in their daily practice
Izgradnja novih ribnjačkih kapaciteta u podunavlju (SAP Vojvodina i SR Srbija) gledana u svetlu ekonomskih problema slatkovodnog ribarstva u SR Hrvatskoj
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