Dust emission from high latitude cirrus clouds

In order to study dust emission from grains in the interstellar medium, the infrared properties were analyzed in a number of isolated high latitude dust clouds which contain no dominant internal heating sources. The clouds are spatially resolved, have a simple geometry, and are mapped in the IRAS bands at 12, 25, 60, and 100 microns. For a number of these clouds, extinction data (A sub B) were obtained from starcounts. A large part (30 to 50 percent) of the infrared radiation of the clouds in the IRAS wavelength range of 8 to 130 micron is emitted in the short wavelength bands at 12 and 25 micron. The 60/100 micron ratios for the integrated fluxes of the clouds have a typical value of 0.19 + or - 0.05

Dynamical correlations in electronic transport through a system of coupled quantum dots

Current auto- and cross-correlations are studied in a system of two capacitively coupled quantum dots. We are interested in a role of Coulomb interaction in dynamical correlations, which occur outside the Coulomb blockade region (for high bias). After decomposition of the current correlation functions into contributions between individual tunneling events, we can show which of them are relevant and lead to sub-/supper-Poissonian shot noise and negative/positive cross-correlations. The results are differentiated for a weak and strong inter-dot coupling. Interesting results are for the strong coupling case when electron transfer in one of the channel is strongly correlated with charge drag in the second channel. We show that cross-correlations are non-monotonic functions of bias voltage and they are in general negative (except some cases with asymmetric tunnel resistances). This is effect of local potential fluctuations correlated by Coulomb interaction, which mimics the Pauli exclusion principle

Ultra-fast current aided sintering of high coercive magnetic powders and composites

The paper refers to pulverization and sintering of the (Fe80Nb6B14)0.88Tb0.12 high coercive alloy. The powder was sintered using the ultra-fast current aided method. It turned out that too long discharge time leads to appearing of a soft magnetic phase and simultaneously, decrease in coercivity of the compacted powder. Nevertheless, it was possible to establish preference technology parameters, preserving magnetic hardness of the alloy. As a final test, an impact of Co-powder addition on magnetic properties was studied. The introduced soft magnetic phase (about 20 wt. %) caused about 30% increase of magnetic remanence, which is a result of direct exchange interactions between the two phases

Discovery and quantitative spectral analysis of an Ofpe/WN9 (WN11) star in the Sculptor spiral galaxy NGC 300

We have discovered an Ofpe/WN9 (WN11 following Smith et al.) star in the Sculptor spiral galaxy NGC 300, the first object of this class found outside the Local Group, during a recent spectroscopic survey of blue supergiant stars obtained at the ESO VLT. The light curve over a five-month period in late 1999 displays a variability at the 0.1 mag level. The intermediate resolution spectra (3800-7200 A) show a very close resemblance to the Galactic LBV AG Car during minimum. We have performed a detailed non-LTE analysis of the stellar spectrum, and have derived a chemical abundance pattern which includes H, He, C, N, O, Al, Si and Fe, in addition to the stellar and wind parameters. The derived stellar properties and the He and N surface enrichments are consistent with those of other Local Group WN11 stars in the literature, suggesting a similar quiescent or post-LBV evolutionary status.Comment: 9 pages, 4 figures, 2 tables. Accepted for publication in the Astrophysical Journal Letter

Типовая учебная программа по учебной дисциплине для специальности: 1-23 01 08 Журналистика (по направлениям), направление специальности 1-23 01 08-02 Журналистика (аудиовизуальная)

Enhancement of soft magnetic properties in the selected group of amorphous alloys was examined by different experimental methods. It was shown that permeability for annealed samples (at Ta for 1 h; 300 K < Ta < 900 K) plotted vs. Ta shows a maximum at which is 700, 725, 725, and 750 K for Fe82Nb2B14Y2, Fe82Nb2B14Gd2, Fe82Nb2B14Tb2 and Fe82Nb2B14Dy2 alloy, respectively. For samples after the optimization annealing permeability is at least 10 times higher than in the as-quenched state. The optimized microstructure is free of iron nanograins and corresponds to so-called relaxed amorphous phase

First <i>In Situ</i> Terrestrial Osbornite (TiN) in the Pyrometamorphic Hatrurim Complex, Israel

AbstractOsbornite (TiN) is extremely rare in nature (commonly found in enstatite meteorites) and has not yet been identified correctly to form naturally in terrestrial settings. Due to its thermodynamic stability and thermal shock resistance, TiN has wide industrial applications, mainly as coatings. However, as the melting temperature of TiN is very high (~3000°С), coatings are produced at much lower temperatures via physical or chemical vapor deposition. Also, anthropogenic analogues of osbornite are often observed in pyrometallurgical slags. Therefore, it is critical to distinguish between anthropogenic and naturally occurring osbornite. A detailed petrographic study was undertaken on in situ osbornite found within unusual gehlenite-bearing breccias from wadi Zohar, Negev Desert of the pyrometamorphic Hatrurim Complex. The Hatrurim Complex, which extends through Israel, Palestine, and Jordan within the Dead Sea Rift zone, mainly comprises larnite, gehlenite, and spurrite rocks. Osbornite, in close association with iron phosphides, barringerite, and schreibersite, occurs at contacts between gehlenite, paralava, and calcinated clasts of host sedimentary rocks. Based on investigation of pseudowollastonite and Fe-P series phases, osbornite is formed at low pressure, extremely high temperatures (~1200-1500°С), and reduced conditions, following pyrolysis of organic matter contained in the sedimentary protolith. This is the first identification of in situ osbornite in terrestrial rocks and indicates that high-temperature and highly reduced conditions, which are common for meteorites, may occur at/near the Earth’s surface as a result of sustained pyrometamorphism in particular settings. Our findings also provide relevant data and criteria for comparing osbornite occurrences elsewhere and ultimately evaluating their origins

Atomic and electronic structure of graphene oxide/Cu interface

The results of X-ray photoemission (XPS) and valence bands spectroscopy, optically stimulated electron emission (OSEE) measurements and density functional theory based modeling of graphene oxide (GO) placed on Cu via an electrophoretic deposition (EPD) are reported. The comparison of XPS spectra of EPD prepared GO/Cu composites with those of as prepared GO, strongly reduced GO, pure and oxidized copper demonstrate the partial (until C/O ratio about two) removal of oxygen-containing functional groups from GO simultaneously with the formation of copper oxide-like layers over the metallic substrate. OSEE measurements evidence the presence of copper oxide phase in the systems simultaneously with the absence of contributions from GO with corresponding energy gap. All measurements demonstrate the similarity of the results for different thickness of GO cover of the copper surface. Theoretical modeling demonstrates favorability of migration of oxygen-containing functional groups from GO to the copper substrate only for the case of C/O ratio below two and formation of Cu-O-C bonds between substrate and GO simultaneously with the vanishing of the energy gap in GO layer. Basing on results of experimental measurements and theoretical calculations we suggest the model of atomic structure for Cu/GO interface as Cu/CuO/GO with C/O ratio in gapless GO about two.Comment: 22 pages, 14 figures, accepted to Thin Solid Films journa