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Publikacije (45045)

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N. Atodiresei, Jens Brede, P. Lazic, V. Caciuc, G. Hoffmann, R. Wiesendanger, S. Blügel

By means of ab initio calculations and spin-polarized scanning tunneling microscopy experiments the creation of a complex energy dependent magnetic structure with a tailored spin-polarized interface is demonstrated. We show this novel effect by adsorbing organic molecules containing π(p(z)) electrons onto a magnetic surface. The hybridization of the out-of-plane p(z) atomic-type orbitals with the d states of the metal leads to the inversion of the spin polarization at the organic site due to a p(z)-d Zener exchange-type mechanism. As a key result, we demonstrate the possibility to selectively and efficiently inject spin-up and spin-down electrons from a ferromagnetic-organic interface, an effect which can be exploited in future spintronic devices.

Jens Brede, N. Atodiresei, S. Kuck, P. Lazic, V. Caciuc, Y. Morikawa, G. Hoffmann, S. Blügel et al.

We investigate the spin- and energy-dependent tunneling through a single organic molecule (CoPc) adsorbed on a ferromagnetic Fe thin film, spatially resolved by low-temperature spin-polarized scanning tunneling microscopy. Interestingly, the metal ion as well as the organic ligand show a significant spin dependence of tunneling current flow. State-of-the-art ab initio calculations including also van der Waals interactions reveal a strong hybridization of molecular orbitals and substrate 3d states. The molecule is anionic due to a transfer of one electron, resulting in a nonmagnetic (S=0) state. Nevertheless, tunneling through the molecule exhibits a pronounced spin dependence due to spin-split molecule-surface hybrid states.

V. Sesar, I. Mišković, T. Šijak

The application of intelligent controllers such as neural networks and fuzzy controllers in technical systems is increasing. The main reason for this lies in the fact that intelligent controllers do not require knowing the exact mathematical model parameters of the controlled process. On the other hand, a great downside to this type of control is that stability cannot be proved. Technical systems often exhibit nonlinear behaviour which can be described with elementary nonlinear elements such as hysteresis and/or dead zones. This paper presents the use of the describing function as a means of analysis of systems with neural networks and dominant nonlinearities. The equivalent describing function can then be used for stability analysis using, for example, the Popov criterion.

D. Gadžo, Mirha Djikić, T. Gavrić, P. Štrekelj

The aim of this study was to compare the tannin concentration of young common and tartary buckwheat plants. Tannins are a group of polyphenols, formed as secondary metabolites in plants. Tannins are known as antioxidants and have chemoprotective potential. They occur in many fruits and drinks, such as tea, beer, wine and juices, making them significant in human nutrition. Concentration of tannins was high in upper leaves of tartary buckwheat and in young plants of common buckwheat cv. Bosanka. There are interesting differences between tannin concentration in Bosanka young plants and tartary and Darja buckwheat young plants.

R. Veličković-Radovanović, J. Petrović, B. Kodela, S. Janković

The mortality rate from cardiovascular diseases is high in Serbia. Analysis of antihypertensive drugs utilization is the basis for assessment of cardiovascular pharmacotherapy appropriateness. The aim of this study was to analyze the trend in antihypertensive drugs utilization among outpatients in Niš region, South Serbia compared to some Nordic countries (Norvay, Sweden) and Australia as well as to analyze trends in educational and drug promotion activities directed to primary healthcare workers within the same region. Using the ATC/DDD methodology, we analyzed the utilization of antihypertensive drugs dispensed on prescription in the Nis region over the 2003–2007 period. The study was retrospective, based on data obtained from Central City Pharmacy Nis. Educational and drug promotion activities were noted from the records of Medical Faculty, University of Nis, and from the records of local branches of pharmaceutical companies active in Serbia. Wilcoxon’s test was used in order to calculate the statistical significance of difference. A significant increase of 79.8% (153.8/ 276.6 DDD/inhabitants/day) in antihypertensive drug consumption was observed in the same period. This analysis showed there were substantial increases in the use of diuretics (134.7%), ACE inhibitors (79.5%) and calcium channel blockers (116.1%), especially amlodipin (241.2%). During the observed period, annual numbers of educational activities and of pharmaceutical sales representatives employed within the region increased for almost one fourth. This analysis pointed to a significant increase in the use of antihypertensive drugs in the Nis region, which was matched with increase in educational and drug promotion activities within the region, so that in 2006–2007 total consumption was approximate to some referential countries (Norvay, Sweden).

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