Magnetic properties of polymerized C60_{60} with Fe

We provide evidence that high-pressure high-temperature (2.5 GPa and 1040 K) treatment of mixtures of iron with fullerene powders leads to the complete transformation of iron into iron carbide Fe$_3$C. The comparison of the magnetic properties (Curie temperature and magnetic moment) of the here studied samples and those for the ferromagnetic polymer Rh-C$_{60}$ indicates that the main ferromagnetic signal reported in those samples is due to Fe$_3$C and not related to the ferromagnetism of carbon as originally interpreted. Taking into account the results obtained in this study the original paper on ``Magnetic carbon" (Nature {\bf 413}, 716 (2001)) was recently retracted.Comment: 5 Figures, 4 page

BLENDING PEDAGOGY AND DIGITAL TECHNOLOGY TO TRANSFORM EDUCATIONAL ENVIRONMENT

This article shows efficacy of competences-oriented education model, representing effectiveness of pedagogy technology and digital tools blending in transforming education while using tutor’s support. In correspondence to contemporary requirements and education system special features, connection between digital education tools and tutor technology contributing to students’ key competences development is determined. The paper contributes to the field by summarizing some theoretical issues and offering implementation suggestions for effectively integrating digital technologies into teaching and learning. The use of digital technologies in educational activities opens up new opportunities, adequate methods for dissemination and management of digital information, development of necessary competencies on the basis of digital literacy, ensuring equitable access for all who wish to obtain necessary knowledge and decision-making skills, ensuring demand for school graduates in the world labor market in situation of digital economy. Innovative technologies become a problem adding difficulties to students’ burden. Tutor becomes an intermediary between students and digital technologies to promote students’ active learning practices; there are not so many students who can appreciate digital learning practices and get the most of it. The role of tutoring in digital literacy promotion is hard to overestimate. Tutor support is a pedagogical activity in individualization of education aimed at identifying and developing students’ educational motives and interests. To form students’ key competencies in education system, it is necessary to supplement traditional education with tools of digital educational technologies, new trends in pedagogies such as tutoring, which is becoming an integral part of modern learning process

Spin-transfer mechanism of ferromagnetism in polymerized fullerenes: AbinitioAb initio calculations

A mechanism of the high temperature ferromagnetism in polymerized fullerenes is suggested. It is assumed that some of the C$_{60}$ molecules in the crystal become magnetically active due to spin and charge transfer from the paramagnetic impurities (atoms or groups), such as hydrogen, fluorine, hydroxyl group OH, amino group NH$_2$, or methyl group CH$_3$, dispersed in the fullerene matrix. The exchange interaction between the spins localized on the magnetically active fullerenes is evaluated using \textit{ab initio} calculations. The nearest neighbour and next nearest neighbour exchange interaction is found to be in the range $0.1\div 0.3$ eV, that is, high enough to account for the room temperature ferromagnetism.Comment: typos corrected, 8 pages, 3 figures, LaTe

Neka zapažanja o etnojezičkoj situaciji u dvojezičnim makedonsko-albanskim selima u regionu Prespa: fenomen Arvati

This paper provides an analysis of the language situation in the villages of the multi-ethnic Prespa region (Republic of Macedonia): Krani and Arvati. The language situation in these villages appears to be especially noteworthy in juxtaposition with the general language situations in Republic of Macedonia. Interestingly, the local bilingualism has no religion restrictions, so Orthodox Macedonians master Albanian language, which is unusual for other Macedonian regions. The most significant features of the Prespa language situation are the following: 1) a relatively high degree of linguistic competence of Macedonian informants in the Albanian language; 2) the young age of second language acquisition; 3) the use of the Albanian language as a primary means of communication within the village; 4) the absence of code-mixing in the narrative

ACS imaging of 25 galaxies in nearby groups and in the field

We present HST/ACS images and color-magnitude diagrams for 25 nearby galaxies with radial velocities V_LG < 500 km/s. Distances are determined based on the luminosities of stars at the tip of the red giant branch that range from 2 Mpc to 12 Mpc. Two of the galaxies, NGC 4163 and IC 4662, are found to be the nearest known representatives of blue compact dwarf (BCD) objects. Using high-quality data on distances and radial velocities of 110 nearby field galaxies, we derive their mean Hubble ratio to be 68 km/(s Mpc) with standard deviation of 15 km/(s Mpc). Peculiar velocities of most of the galaxies, V_pec = V_LG - 68 D, follow a Gaussian distribution with sigma_v = 63 km/s, but with a tail towards high negative values. Our data displays the known correlation between peculiar velocity and galaxy elevation above the Local Supercluster plane. The small observed fraction of galaxies with high peculiar velocities, V_pec < -500 km/s, may be understood as objects associated with nearby groups (Coma I, Eridanus) outside the Local volume.Comment: 17 pages, 8 figures, accepted to A

Kramers-Kronig constrained variational analysis of optical spectra

A universal method of extraction of the complex dielectric function $\epsilon(\omega)=\epsilon_{1}(\omega)+i\epsilon_{2}(\omega)$ from experimentally accessible optical quantities is developed. The central idea is that $\epsilon_{2}(\omega)$ is parameterized independently at each node of a properly chosen anchor frequency mesh, while $\epsilon_{1}(\omega)$ is dynamically coupled to $\epsilon_{2}(\omega)$ by the Kramers-Kronig (KK) transformation. This approach can be regarded as a limiting case of the multi-oscillator fitting of spectra, when the number of oscillators is of the order of the number of experimental points. In the case of the normal-incidence reflectivity from a semi-infinite isotropic sample the new method gives essentially the same result as the conventional KK transformation of reflectivity. In contrast to the conventional approaches, the proposed technique is applicable, without readaptation, to virtually all types of linear-response optical measurements, or arbitrary combinations of measurements, such as reflectivity, transmission, ellipsometry {\it etc.}, done on different types of samples, including thin films and anisotropic crystals.Comment: 10 pages, 7 figure