Određivanje Štarkovog pomaka i stope jonizacije atomskih sistema sa jednim i sa dva aktivna elektrona u spoljašnjem električnom polju metodom kompleksne rotacije

The subject of this Doctoral Dissertation is the study of atomic systems in external static electric field, which can be described using models with one or two active electrons. The main aim of the dissertation is determination of the Stark shift of the lowest state and the ionization rate (or the electron detachment rate in the case of ions) depending on the field strength. The calculations are performed using the complex rotation (scaling) method with the expansion of trial wave functions in the basis of Coulomb Sturmians. The sistems analyzed here are the hydrogen atom, alkali-metal atoms (lithium, sodium, potassium, rubidium, cesium, francium), helium atom, and the hydrogen negative ion. For alkali-metal atoms several types of pseudopotential are used, while the two-electron systems are studied by applying the exact two-electron description as well as single-electron approximations. A good agreement with the results of other authors, who used similar (numerical) methods, and with the formulas of standard theoretical description in the case of weak field, is obtained. An important result is also an analysis of applicability of the methods and models used for the considered system

Aerosol Route as a Versatile Method for the Processing of Hierarchically Organized Hybrid Nano Particles

Hierarchical structures, which refers to the materials that have more than one length scale, organized as the assemblage of primary units with high surface-to-volume ratio, play an important role in advanced materials design. Especially, the building of complex hierarchical structures exhibiting the hybrid organic-inorganic interfaces might be of special importance for the creation of advanced nanostructured materials having either improved or novel characteristics that bridges various scientific areas for the future diverse technological applications in catalysis, optics, energy, life science etc. Applying the bottom-up building blocks approaches, it is possible to create the hierarchical structures in a controlled manner having different morphologies, starting from aqueous, organic or colloidal precursor solutions. Among the diversity of the “bottom-up” chemical approaches, synthesis through dispersion phase (aerosol) enables generation of ultrafine, either single or complex structures with controlled stoichiometry, chemical and phase content. The opportunities of the hot wall aerosol processing, provided by high heating and cooling rates, short residence time and high surface reaction, refers to the synthesis of spherical three-dimensional (3D), hierarchically organized nanostructured particles with uniformly distributed components and phases. The particles composite inner structure, representing an assembly of nanosized primary particles, opens the possibility for particle surface modification and functionalization emphasizing their application in photovoltaics, energy transfer and bioimaging. This versatile technique has been used for the successful synthesis of hierarchically organized submicronic titanium (IV) oxide or Y2O3 up-conversion phosphor particles having the diverse levels of structural, morphological and functional complexity explored by means of appropriate selection of different precursor solutions, either true or colloid, surface modification and proper selection of rare-earth based dopants

Uticaj metoda oplodnje genotipa, pola i tipa rođenja na porast jagnjadi

Estrus synchronization methods was use to control the reproductive traits of sheep, as well as bringing more females at the same stage of estrus and ovulation. According to the points mentioned above, the aim of the present study was to investigate and compare mating method and influence of fixed factors on birth and weaning weight of lambs. Statistical analysis showed that exist difference in the body weights between genotypes of lambs. In the first group, the difference in weight of lambs at birth, regardless of mating method was not significant (P> 0.05), while in the second group, the difference was slightly significant (P (lt) 0.05). As for the birth type, sex and within the same genotype, there was a statistical significance (P (lt) 0.05) between singles obtained naturally, between the triplets obtained naturally and between triplets received hormonal method. All the differences between body weight at 30 days (mating method, sex and birth type under the same genotype) were statistically significant (P (lt) 0.05).The determined differences in the body weights at 60 days (sex, mating method and type of birth under the same genotype) were statistically significant (P (lt) 0.05). The results showed that the differences (mating method, sex and type of birth under the same genotype) were statistically significant (P (lt) 0.05), except in between body weight at 90 days in twins among two genotypes obtained by natural method, which were not statistically significant (P> 0.05).Metod sinhronizacije estrusa se koristi da kontroliše reproduktivne osobine ovaca. Cilj ovog rada bio je da se ispita i uporedi način parenja i uticaj osnovnih fiksnih faktora na masu jagnjadi. Statistička analiza je pokazala da je razlika telesne mase između grupa jagnjadi na rođenju bila statistički značajna. U prvoj grupi, razlika u masi jagnjadi na rođenju, zavisno od načina oplodnje nije bila značajna (P> 0,05), dok je u drugoj grupi, razlika statistički značajna (P (lt) 0,05). Što se tiče tipa rođenja, a u okviru istog genotipa, postoji statistička značajnost (P (lt) 0,05) između jedinaca dobijenih prirodno, između prirodno dobijenih trojki i između trojke dobijenih hormonskim metodom. Sve razlike između masa tela muških grla sa 30 dana (načinu oplodnje, tipa rođenja i u okviru istog genotipa) su statistički značajne (P (lt) 0,05). Utvrđene razlike u telesnoj masi sa 60 dana su takođe statistički značajne (P (lt) 0,05). Rezultati su pokazali da su razlike između genotipova pod uticajem fiksnih faktora statistički značajne (P (lt) 0,05), osim između telesne mase sa 90 dana kod blizanaca (P> 0,05)

Influence of printing parameters on the eligibility of plane-strain fracture toughness results for PLA polymer

The majority of manufacturers of polymer filaments for FDM technology rely their datasheets only on tensile tests, so their documentation usually lacks any data concerning fracture mechanics parameters. Having in mind the importance of fracture mechanics parameters in material design and application e.g., plane-strain fracture toughness, and the fact that it can be measured using only standard tensile grips, or three-point bending test fixture on a regular tensile testing machine, this practice offers vital information for AM components carrying the load. Anyhow, it is not always a simple task to satisfy all requirements of the standard for plane-strain fracture toughness assessment of plastic materials (ASTM D5045-14), as in the case of FDM technology due to many printing parameters that not only influence fracture toughness results, but also can question the eligibility of test results if crack propagation deviates from the expected path or if the specimens don't meet the size criterion necessary for achieving the plane-strain condition. These problems are tackled in this research on PLA polymer, a material widely used in FDM technology. For this research SENB specimens are prepared according to ASTM D5045-14 standard and tested on tensile testing machine using three-point bending test fixtur

Antiproliferative effects of some medicinal plants on HeLa cells

Medicinal plants maintain the health and vitality of individuals, and also have potential curative effect on various diseases, including cancer. In this study were investigated the antiproliferative effects of water extracts of previously obtained ethanolic dry extracts of three different medicinal plants (Echinacea angustifolia, Salvia officinalis and Melissa officinalis) on cell lines derived from human cervix adenocarcinoma (HeLa cells). The best cytotoxic activity (IC50 = 43.52 μg/ml) on HeLa cell lines was exhibited by Echinacea angustifolia. The extract of Salvia officinalis also showed a good cytotoxic activity against HeLa cell lines; the IC50 value was 70.41 μg/ml. Melissa officinalis manifested a slightly weaker cytotoxic activity and an IC50 value of 122.22 μg/ml. [Projekat Ministarstva nauke Republike Srbije, br. 34021 i br. 175011

Two-band superconductors: Hidden criticality deep in the superconducting state

We show that two-band superconductors harbor hidden criticality deep in the superconducting state, stemming from the critical temperature of the weaker band taken as an independent system. For sufficiently small interband coupling $\gamma$ the coherence length of the weaker band exhibits a remarkable deviation from the conventional monotonic increase with temperature, namely, a pronounced peak close to the hidden critical point. The magnitude of the peak scales proportionally to \gamma^(-\mu), with the Landau critical exponent \mu = 1/3, the same as found for the mean-field critical behavior with respect to the source field in ferromagnets and ferroelectrics. Here reported hidden criticality of multi-band superconductors can be experimentally observed by, e.g., imaging of the variations of the vortex core in a broader temperature range. Similar effects are expected for the superconducting multilayers.Comment: 6 pages, 2 figures, Supplementary material included. Accepted for publication in PR

Influence of frequency offset on the reception of OFDM/QPSK signal using MBDD algorithm

In this paper we present the basic characteristics of Orthogonal Frequency Division Multiplex (OFDM) systems with quadrature phase shift keying (QPSK) modulation and multi-bit differential detection (MBDD). In the simulation environment designed for this purpose, we analyze the effects of frequency offset on the performances of OFDM digital communications. We also analyze the influence of OFDM system parameters on system performances for various values of frequency offset, number of bits for multi-bit detection and the number of subcarriers. We have shown the advantages and disadvantages of using MBDD in the OFDM systems