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

ENHANCED DIELECTRIC PROPERTIES IN LA MODIFIED BARIUM TITANATE CERAMICS

Donor/acceptor (La/Mn) doped BaTiO3 ceramics, sintered at different temperatures, were studied regarding their microstructure and dielectric properties as well as the dielectric response in a ferroelectric/paraelectric regime. The concentrations of La3+ as donor, ranging from 0.1 to 5.0 at% were used for doping, while a content of Mn4+ as acceptor was at 0.05 at% in all samples. The sintering temperature of codoped samples were 1290°and 1350°C.A reduction in grain size and fine-grained microstructure with average grain size from 0.5 to 2.0 mm was observed in low doped samples, whereas the abnormal growth of individual grains took place in the 2 at% and 5 at% La doped specimens. The dielectric properties of these samples were investigated as a function of frequency (100Hz – 20 kHz) and temperature (20-180°C). The measured results suggested that both the dielectric constants of the ceramics (er at room temperature and ermaxat the Curie temperature) decreased as the concentration of La3+ increased.The dielectric permittivity was in the range of 944 to 3200. For samples doped with 0.1 at% La and sintered at 1350°C, the highest dielectric constant value at room temperature (er= 3200) and Curie temperature (er= 5000) were measured. For all measured samples the dissipation factor was less than 0.09. With an increase in La contents, dielectric measurements exhibited shift in the Curie temperature (Tc) towards the low temperature.Using the Curie-Weiss and the modified Curie-Weiss law, Curie's constant C was calculated as well as the parameterg, which describes the deviation from the linear dependence er of T above the phase transformation temperature. The calculated values for g  ranged from 1.01 to 1.43. These values indicate a sharp phase transformation in low-doped and diffuse phase transformation in highly La doped samples. The phase transition was reflected in the values of C that started to decrease with increasing dopant content

Analiza proteina u semenu pšenice (Triticum aestivum L.)

The protein in seed of wheat play a major role in determining the quality of wheat. The aim is to study the variability of the composition of the gene alleles of gliadins, and the glutenin content, total protein content and dry gluten in bread wheat genotypes. For this study were used seed of bread wheat genotypes grown in two years with different weather conditions. The results showed differences between varieties according to the composition of gliadin and glutenin, and according to the obtained values for the content of protein and gluten content. At the three Glu-1 loci were identified nine alleles, while at the three Gli-1 loci 13 alleles and at the three Gli-2 loci were identified 16 alleles. Composition of identified alleles was different in the wheat genotypes, and composition of glutenin alleles was specific for seven genotypes while three genotypes (G-3539/03, Poljana and G-3602/03) possessed the same allele (b, c, d). The protein and gluten content is varied depending on the genotype and environmental factors, The genotypes G-3602/03 had the lowest contents of protein 11,6% and gluten 10.018, while G-3539/03 had the highest content of protein 15.00% and dry gluten 14.086% in both years of experiment. Varying the content and composition of proteins is correlated with the properties of wheat quality.Proteini u semenu pšenice imaju glavnu ulogu u formiranju kvaliteta pšenice. Cilj rada je izučavanje varijabilnosti kompozicije genskih alela za glijadine i glutenine, sadržaja ukupnih proteina i sadržaja suvog glutena kod genotipova hlebne pšenice. Za ovo izučavanje je korišćeno seme 10 genotipova hlebne pšenice gajene u dve godine sa različitim vremenskim uslovima. Rezultati istraživanja su pokazali razlike izmedju sorti prema kompoziciji glijadina i glutenina, kao i prema dobijenim vrednostima za sadržaj proteina i sadržaj glutena. Na tri lokusa za visokomolekularne glutenine (Glu-1) je identifikovano devet alela, a na šest lokusa za glijadine je identifikovano ukupno 29 alela i to 13 alela na tri lokusa Gli-1 i 16 alela na tri lokusa Gli-2. Sastav glijadinskih alela je bio različit kod izučavanih genotipova pšenice, dok je sastav gluteninskih alela bio isti (b, c, d) kod tri genotipa (G-3539/03, Poljana i G-3602/03) a kod ostalih sedam sorti je bio različit. Sadržaj proteina je varirao zavisno od genotipa i od godine eksperimenta i to od 11,60% (G-3602/03 u prvoj godini) do 15,00% (G-3539/03 u drugoj godini). Sadržaj suvog glutena je varirao od 10,018% (G-3602/03 u prvoj godini) do 14,0860% (G-3539/03 u drugoj godini istraživanja). Kod izučavanih genotipova pšenice je ustanovljena heterogenost Glu-A1 lokusa (kod G-3908/03) i Glu-B1 lokusa (G-3602/03), kao i heterogenost Gli-A1 lokusa (G-3504/03 i G-3532/03), Gli-D1 lokusa (G-3908/03) i Gli-A2 lokusa (G-3908/03 i Žitnica). Kompozicija alela je bila ista u obe godine kod svih 10 genotipova, a sadržaj proteina i glutena je varirao, čije vrednosti su bile veće u drugoj godini eksperimenta

Fractal Nature Complex Correction an Inductivity

The microstructures properties predicting are based on their materials characteristics. In ceramic materials, regarding higher miniaturization and integrations, the structure analysis is very important. The main contribution of this research is related to relation between perovscites ceramics electronic properties, especially BaTiO3 and NZT-ceramics and structural characteristics. We applied advanced analysis, based on fractal nature and introduced complex fractal correction in defining the very important electromagnetic parameter inductivity (L). The samples consolidation includes both, powder pressing (cold sintering) and hot sintering. The fractal characterization performs very important role from powders up to the final structures, through which exists structure influence on electro-physical and other ceramic properties. We report the experimental results of BaTiO3 and NZT-ceramics processing. Also, this is the first time that we apply complex fractal correction (influence of grains and pore surface and as well as particles Brownian motion) on fundamental thermodynamic temperature in Currie-Weiss law. This application includes the influence of Housdorff dimension (DH) from the microstructure images and connect fractal corrections in Currie-Weiss law, for relative dielectric constant ϵr and magnetic permeability μr. Through ϵr and μr, on this way, for the first time in this scientific area, we present direct relation to inductivity. This complex relation opens quit new advance understanding in structures and parameters in area of ferroelectic-magnetic applications in telecommunications, by introducing the fractals.acceptedVersionPeer reviewe

Mechanisms of protective effects of moderate alcohol consumption on the cardiovascular system

Consumption of alcoholic beverages has been known in many cultures since the ancient civilizations, so harmful consequences of excessive alcohol intake have been well explained. Many epidemiological studies confirmed lower morbidity and mortality rates of cardiovascular diseases in persons who drink alcohol "moderately" (1-2 drinks a day), independently of the kind of alcoholic beverage. This paper presents the review of molecular mechanisms that are believed to explain cardioprotective effect of moderate drinking-alcohol effects on lipoproteins, endothelial cells, blood clot formation and dissolution, as well as genetic and gender variances modifying the relation. A simple recommendation regarding the increase of alcohol consumption cannot be made on population level. The professionals must therefore concentrate on other preventive methods in order to reduce other significant risk factors of cardiovascular diseases

Distance based topological indices on multiwall carbon nanotubes samples obtained by electrolysis in molten salts

The interest for the intensive studies and methods of structural characterization of multiwall carbon nanotubes (MWCNTs) to date has resulted in many valuable contributions and an amazingly wide application area. This paper offers an approach that combines several techniques. It is the first direct application of the graph theory upon nanotubical structures obtained by electrolysis in molten salts using non-stationary current regimes. The spectroscopic data enables studying the diameters and performing an (n,m) assignment of nanotube samples. Using the graph representation and the chirality of the studied samples, different distance based topological indices (Wiener, Balaban, Sum-Balaban, and Gutman indices) have been evaluated in order to enable further prediction of index-related properties of the molecules

Revision of bank vole Clethrionomys glareolus (Schreber, 1780) (Mammalia, Rodentia) distribution in Serbia and Montenegro

The present article represents a complete review of all published data (with corrections) on bank vole Clethrionomys glareolus distribution in Serbia and Montenegro. On the other hand, data of 63 unpublished records stored in the period from 1956 to 1983 in the Mammal Study Collection of the Natural History Museum, Belgrade had not been processed until now. In the period from 1992 to 2004, 29 new findings were recorded, 12 of them outside the currently known area of distribution. New data reveal a wider distribution of bank vole than was known until now, completing and partly modifying previous knowledge about this rodent's bionomy and ecology in Serbia and Montenegro. The occurrence of bank vole in the Prokletije Mountains, Kosovo and Metohija represents its highest known altitude in Europe (2500 m). On the basis of these new data and observations, we can conclude that bank vole is continuously present in small and linear fragments of autochthonous woodlands on plains and hills, and that there are no large discontinuities in its distribution in Serbia and Montenegro, as was assumed earlier. In efforts to preserve overall biological diversity, the example of the bank vole underlines the need to intensify protection and management of woodlands especially remaining fragments of forests on plains and in hills.U ovom radu daje se kompletan pregled i ispravka do sada objavljenih podataka o rasprostranjenju Clethrionomys glareolus u Srbiji i Crnoj Gori. S druge strane, podaci o 63 nova nalaza deponovani su od 1956. do 1983. godine u Studijskoj zbirci sisara Prirodnjačkog muzeja u Beogradu i do sada nisu obrađivani. U periodu od 1992. do 2004. godine zabeleženo je 29 novih nalaza od čega 12 van do sada poznatog areala. Novi podaci govore o širem rasprostranjenju riđe voluharice nego što je to do sada bilo poznato upotpunjujući i donekle modifikujući dosadašnja saznanja o bionomiji i ekologiji ovog glodara u Srbiji i Crnoj Gori. Nalazište na Prokletijama Kosovo i Metohija, nalazi se na najvećoj nadmorskoj visini u Evropi, 2500 m. Na osnovu novih podataka i opservacija zaključuje se da je riđa voluharica kontinuirano prisutna u malim i linearnim fragmentima autohtonih šuma u nizijama i pobrđu, kao i da u arealu ove vrste u Srbiji i Crnoj Gori ne postoje veliki diskontinuiteti kako je ranije pretpostavljano. U cilju očuvanja ukupne biološke raznovrsnosti, primer riđe voluharice ukazuje na potre- bu intenziviranja zaštite i očuvanja šumskih staništa, a naročito preostalih malih i/ili linearnih fragmenata nizijskih šuma i šuma u pobrđu.Grants #1525, #1864, and #156

Cardiovascular effects of environmental noise: Research in Serbia

Research on the cardiovascular effects of noise in Serbia started in the year 2002, including experimental studies on humans and epidemiological studies on the adult and children population of Belgrade and Pancevo. Experimental exposure to noise [L eq = 89 dB (A)] had a hypodynamic effect, significantly lowering the cardiac index, cardiac work, and pump performance (P 45 dB (A)] and quiet areas [(L night , 8h ≤ 45 dB (A)] were 23.6% and 17.5%, respectively. The adjusted odds ratio (OR) for hypertension of the exposed group was 1.58 (95% CI = 1.03 - 2.42, P = 0.038), where men living in quiet streets were taken as a reference category. Associations between road traffic noise and blood pressure were also investigated in 328 preschool children in Belgrade. The systolic blood pressure was significantly higher among children from noisy residences and kindergartens, compared to children from both quiet environments (97.30 ± 8.15 and 92.33 ± 8.64 mmHg, respectively, P < 0.01). As a continuation of the study on preschool children, investigations were also carried out on 856 school children, aged between seven and eleven years, in Belgrade. It was found that systolic pressure was significantly higher among children from noisy schools and quiet residences, compared to children from both quiet environments (102.1 ± 9,3 and 100.4 ± 10.4 mmHg, respectively, P < 0.01)

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