Vibrational properties of alpha- and sigma-phase Fe-Cr alloy

Experimental investigation as well as theoretical calculations, of the Fe-partial phonon density-of-states (DOS) for nominally Fe_52.5Cr_47.5 alloy having (a) alpha- and (b) sigma-phase structure were carried out. The former at sector 3-ID of the Advanced Photon Source, using the method of nuclear resonant inelastic X-ray scattering, and the latter with the direct method [K. Parlinski et al., Phys. Rev. Lett. {78, 4063 (1997)]. The characteristic features of phonon DOS, which differentiate one phase from the other, were revealed and successfully reproduced by the theory. Various data pertinent to the dynamics such as Lamb-Mossbauer factor, f, kinetic energy per atom, E_k, and the mean force constant, D, were directly derived from the experiment and the theoretical calculations, while vibrational specific heat at constant volume, C_V, and vibrational entropy, S were calculated using the Fe-partial DOS. Using the values of f and C_V, we determined values for Debye temperatures, T_D. An excellent agreement for some quantities derived from experiment and first-principles theory, like C_V and quite good one for others like D and S was obtained.Comment: 4 pages, 3 figure

To realisation of chromatic polynomial calculation algorithm

We calculate chromatic polynomial of an undirected graph using the fundamental reduction theorem and reducing to complete graphs. We also find the chromatic number using the chromatic polynomial. The C++ program was created, the result is obtained in the form of falling factorials and afterwards by the powers of x, the applications of chromatic polynomial are given

Ionosphere-plasmasphere response to geomagnetic storms studied with the RMI-Dourbes comprehensive database

Presented is a review of the ionospheric storm research carried out at the Royal Meteorological Institute (RMI)of Belgium.The studies are based on the opportunities offered by the long-term measurements and the accumulated comprehensive database managed by the RMI Geophysics Centre at Dourbes (4.6 °E,50.1 °N).Reported are case studies of major storms,and also results in developing forecasting and density reconstruction methods

Attosecond streaking of photoelectron emission from disordered solids

Attosecond streaking of photoelectrons emitted by extreme ultraviolet light has begun to reveal how electrons behave during their transport within simple crystalline solids. Many sample types within nanoplasmonics, thin-film physics, and semiconductor physics, however, do not have a simple single crystal structure. The electron dynamics which underpin the optical response of plasmonic nanostructures and wide-bandgap semiconductors happen on an attosecond timescale. Measuring these dynamics using attosecond streaking will enable such systems to be specially tailored for applications in areas such as ultrafast opto-electronics. We show that streaking can be extended to this very general type of sample by presenting streaking measurements on an amorphous film of the wide-bandgap semiconductor tungsten trioxide, and on polycrystalline gold, a material that forms the basis of many nanoplasmonic devices. Our measurements reveal the near-field temporal structure at the sample surface, and photoelectron wavepacket temporal broadening consistent with a spread of electron transport times to the surface

The Role of Euroregions as A Factor of Spatial Integration and Regional Development—The Focus on The Selected Border Area

The political changes that affected the European area in the second half of the 20th century conditioned the development of European countries on the principle of Euroregions, as interesting creations of neighboring countries. Formed along the political borders of neighboring countries, Euroregions today play a significant role in the enlargement process of the European Union. At the end of the 20th century, the formation of Euroregions covered the area of the Western Balkans as well. In Podrinje, the border area of Serbia and Bosnia and Herzegovina, the formed Euroregions have the goal of reviving and revitalizing rural areas. Tourism, as the most important economic activity, is integrated into the basis of the rural development of these areas. The subject of the research is related to the analysis of the development degree of border rural areas, under the influence of tourism. The research problem is focused on the rural areas of “Serbian” Podrinje. Accordingly, the aim of this paper is to determine the change and burden of rural border area due to the development of tourism, using the indicator of tourist operation (I.T.O.) and the tourist function indices to measure the degree of the development of a destination. The results of the research indicate that three types of tourist destinations have been developed in the studied area: destinations with almost non-existent tourist activity (< 4), with small-scale tourist activity (4– 10), and developed and eminently tourist destinations (40–100). The obtained results indicate that 83.3% of the destinations in "Serbian" Podrinje are destinations with almost non-existent tourist activity. These are the destinations where the development of tourism does not affect the transformation of space, but the original and preserved environment is promoted as a tourist attraction. © 2021, Geographical Institute "Jovan Cviji" of the Serbian Academy of Sciences and Arts. All rights reserved.This work was supported by the Serbian Ministry of Education, Science, and Technological Development (Contract No. 451-03-9/2021-14/200172)

Ab initio and nuclear inelastic scattering studies of Fe3_3Si/GaAs heterostructures

The structure and dynamical properties of the Fe$_3$Si/GaAs(001) interface are investigated by density functional theory and nuclear inelastic scattering measurements. The stability of four different atomic configurations of the Fe$_3$Si/GaAs multilayers is analyzed by calculating the formation energies and phonon dispersion curves. The differences in charge density, magnetization, and electronic density of states between the configurations are examined. Our calculations unveil that magnetic moments of the Fe atoms tend to align in a plane parallel to the interface, along the [110] direction of the Fe$_3$Si crystallographic unit cell. In some configurations, the spin polarization of interface layers is larger than that of bulk Fe$_3$Si. The effect of the interface on element-specific and layer-resolved phonon density of states is discussed. The Fe-partial phonon density of states measured for the Fe$_3$Si layer thickness of three monolayers is compared with theoretical results obtained for each interface atomic configuration. The best agreement is found for one of the configurations with a mixed Fe-Si interface layer, which reproduces the anomalous enhancement of the phonon density of states below 10 meVComment: 14 pages, 9 figures, 4 table