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[en] In this paper, electronic structure and the total energy of the URh3 compound in AuCu3 (cubic) and Ni3Sn (hexagonal) type structures have been calculated as a function of reduced volume to compare their structural stability at very high pressures and understand the bonding nature of the f electron states
[en] We calculate optical properties of water along the principal Hugoniot curve from ambient conditions up to temperatures of 130 000 K with density functional theory (DFT) and the Kubo-Greenwood formula. The effect of the exchange correlation functional is examined by comparing the generalized gradient approximation with a hybrid functional that contains Fock exchange. We find noticeable but moderate differences between the respective results which decrease rapidly above 80 000 K. The reflectivity along the principal Hugoniot is calculated and a good qualitative but fair quantitative agreement with available experimental data is found. Our results are of general relevance for calculations of optical properties with DFT at zero and elevated temperature.
[en] Complete text of publication follows. In this work the quantum pseudopotential for pair interaction of particles was considered, which takes into account the diffraction effects due to the uncertainty principle and the coupling between symmetry and diffraction effects in two-component plasma (the region of temperatures 104K < T < 108K and densities 1021 cm-3 < n ≤ 1024 cm-3). Numerically the exact values of the Slater sum based on the method which was presented in work  were calculated. Interpolation formula for the pseudopotential which takes into account the effect of diffraction and many particle quantum effects and is based on the exact numerical values of the Slater sum was founded. The interpolation formula at condition ∞→T has the following form: Φ/T→∞ = eαeβ / r (1 - exp[-r/λαβ]), that corresponds to the Deutsch potential. For higher densities the pseudopotential which does not depend on density was considered. The results are in good agreement with similar data in , but diverge from data of the ion-electron pair's interaction given in . This fact is explained by the different choices of the wave function. In works [5-7] quantum effects which effective potential takes into account were considered.
[en] Stark widths of the singly ionized gallium lines for several triplets and singlets in the visible spectral region are calculated using a modified semi-empirical method (MSEM). Results are given at electron density Ne=1017 cm-3 and at electron temperature ranging from 5000 to 40 000 K. The comparison of our MSEM calculated data with both experimental and semi-classical method (SCM) calculated data, available in the literature, shows good agreement for the triplet lines. But, for the singlet lines, there are no data for comparison
[en] Ellerman bombs (EBs) are small brightening events in the solar lower atmosphere. By their original definition, the main characteristic of EBs is the two emission bumps in both wings of chromospheric lines, such as H α and Ca II 8542 Å lines. Up to now, most authors have found that the temperature increase of EBs around the temperature minimum region is in the range of 600–3000 K. However, with recent IRIS observations, some authors proposed that the temperature increase of EBs could be more than 10 000 K. Using non-LTE semi-empirical modeling, we investigate the line profiles, continuum emission and radiative losses for EB models with different temperature increases, and compare them with observations. Our result indicates that if the EB maximum temperature reaches more than 10 000 K around the temperature minimum region, then the resulting H α and Ca II 8542 Å line profiles and the continuum emission would be much stronger than those of EB observations. Moreover, due to the high radiative losses, a high temperature EB would have a very short lifetime, which is not compatible with observations. Thus, our study does not support the proposal that EB temperatures are higher than 10 000 K. (letters)
[en] The obtained results indicated that physico-chemical and nutritional changes in UHT processed buffalo skimmed milk were more pronounced at 45 deg. C than 25 deg. C and 10 deg. C. Duration of storage adversely affected the chemical and nutritional quality of processed milk. A slight decrease in pH, total ash and lactose contents, was observed, whereas acidity was increased on the mentioned storage conditions. Total nitrogen and casein nitrogen contents gradually decreased during storage, whereas non-casein nitrogen (NCN) and non-protein nitrogen (NPN) increased to a great extent in samples stored at higher temperatures. A significant increase in hydroxyl methyl furfural (HMF) values occurred in UHT processed buffalo skim milk at 25 deg. C and 45 deg. C after of 90 days storage. Storage at high temperature (45 deg. C) caused undesirable effects on sensory properties, general quality characteristics and acceptability of UHT buffalo skimmed milk. (author)
[en] It has been known for over 50 years that the outer atmosphere of the Sun, the so-called corona, has a temperature of 106 K (∼0.1 keV) yet the exact reasons for this are still being debated. The magnetic field that pervades the corona is certainly the source of the heating, but the question is whether the field energy is dissipated via numerous, small, random reconnections (known as 'nanoflares', i.e. small energy releases of about 1016 J) or the damping of magnetohydrodynamic (MHD) waves propagating up from the Sun's surface layers (the photosphere). Some new evidence from the SOHO and Yohkoh spacecraft, with instruments on board which image the Sun in the extreme ultraviolet and soft x-rays, are shedding new light on the problem - it appears that the energy spectrum of small flare-like phenomena may be such that nanoflares are sufficiently numerous to supply the corona's energy requirements. However, these new findings do not preclude the possibility of MHD wave motions also supplying significant amounts of energy. Theory suggests very short period (<1 s) MHD waves are implicated in the heating process if so. Searches during total solar eclipses for modulations of the white-light coronal intensity that may result are being made with increasingly sophisticated equipment. Some very fast imaging systems are now available, and a description is given of a charge-coupled device camera experiment conducted successfully during the recent total solar eclipse visible in Europe. (author)
[en] We report the detection of Ne VIII in an intervening multiphase absorption line system at z = 0.32566 in the Far Ultraviolet Spectroscopic Explorer spectrum of the quasar 3C 263 (zem = 0.646). The Ne VIII λ770 A detection has a 3.9σ significance. At the same velocity, we also find absorption lines from C IV, O III, O IV, and N IV. The line parameter measurements yield log [N(Ne VIII) cm-2] = 13.98+0.10-0.13 and b = 49.8 ± 5.5 km s-1. We find that the ionization mechanism in the gas phase giving rise to the Ne VIII absorption is inconsistent with photoionization. The absorber has a multiphase structure, with the intermediate ions produced in cool photoionized gas and the Ne VIII most likely in a warm collisionally ionized medium in the temperature range (0.5-1.0) x 106 K. This is the second ever detection of an intervening Ne VIII absorption system. Its properties resemble the previous Ne VIII absorber reported by Savage and colleagues. Direct observations of H I and O VI are needed to better constrain the physical conditions in the collisionally ionized gas phase of this absorber.
[en] The heat radiation due to laser-induced heating of local inhomogeneities in borate glass was investigated experimentally. When borate glass is excited by a Q-switched YAG:Nd3+ laser, the heat radiation is reliably detectable without glass damage. The optical properties of the anti-Stokes emission investigated are described on the basis of a simple spherical-particle model. There is agreement between the experimental and calculated data. The local temperature is estimated to be about 10 000-15 000 K. (author)