| 1. |
- Ukleev, V., et al.
(författare)
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Morphology and magnetic properties of nanocomposite magnetic multilayers [(Co(4)oFe(40)B(2)O)(34)(SiO2)(66)]/[C](47)
- 2016
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier BV. - 0022-3093 .- 1873-4812. ; 432, s. 499-504
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Tidskriftsartikel (refereegranskat)abstract
- We report on the investigation of morphology, magnetic and conductive properties of the mutilayered nanostructures [(Co40Fe40B20)(34)(SiO2)(66)]/[C](47) consisting of the contacting magnetic (Co Fe-40 (40) B (20)) (34)(SiO2)(66) nanocomposite and amorphous semiconductor carbon C layers. It is shown by Grazing-Incidence Small-Angle X-ray Scattering method that the ordering and the size of nanoparticles in the magnetic layers do not change profoundly with increasing of carbon layer thickness. Meanwhile, the electrical conductance and the magnetic properties are significantly varied: resistance of the samples changes by four orders of magnitude and superparamagnetic blocking temperature changes from 15 K to 7 K with the increment of carbon layer thickness h(c) from 0.4 nm to 1.8 nm. We assume that the formation of the homogeneous semiconductor interlayer leads to modification of the metal-insulator growth process that drives the changes in the magnetic and conductive properties.
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| 2. |
- Vandaele, Ann Carine, et al.
(författare)
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Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter
- 2019
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Ingår i: Nature. - : Springer. - 1476-4687 .- 1476-4687 .- 0028-0836. ; 568:7753, s. 521-525
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Global dust storms on Mars are rare1,2 but can affect the Martian atmosphere for several months. They can cause changes in atmospheric dynamics and inflation of the atmosphere3, primarily owing to solar heating of the dust3. In turn, changes in atmospheric dynamics can affect the distribution of atmospheric water vapour, with potential implications for the atmospheric photochemistry and climate on Mars4. Recent observations of the water vapour abundance in the Martian atmosphere during dust storm conditions revealed a high-altitude increase in atmospheric water vapour that was more pronounced at high northern latitudes5,6, as well as a decrease in the water column at low latitudes7,8. Here we present concurrent, high-resolution measurements of dust, water and semiheavy water (HDO) at the onset of a global dust storm, obtained by the NOMAD and ACS instruments onboard the ExoMars Trace Gas Orbiter. We report the vertical distribution of the HDO/H2O ratio (D/H) from the planetary boundary layer up to an altitude of 80 kilometres. Our findings suggest that before the onset of the dust storm, HDO abundances were reduced to levels below detectability at altitudes above 40 kilometres. This decrease in HDO coincided with the presence of water-ice clouds. During the storm, an increase in the abundance of H2O and HDO was observed at altitudes between 40 and 80 kilometres. We propose that these increased abundances may be the result of warmer temperatures during the dust storm causing stronger atmospheric circulation and preventing ice cloud formation, which may confine water vapour to lower altitudes through gravitational fall and subsequent sublimation of ice crystals3. The observed changes in H2O and HDO abundance occurred within a few days during the development of the dust storm, suggesting a fast impact of dust storms on the Martian atmosphere.
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| 3. |
- Frolova, Natalia L., et al.
(författare)
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Runoff fluctuations in the Selenga River Basin
- 2017
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Ingår i: Regional Environmental Change. - : Springer Science and Business Media LLC. - 1436-3798 .- 1436-378X. ; 17:7, s. 1965-1976
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Tidskriftsartikel (refereegranskat)abstract
- The Selenga River has historically provided 50% of the total freshwater water input to the Lake Baikal, transporting substances and pollutants that can considerably impact the unique lake ecosystem. In the context of on-going regional to global change, we here aim at identifying and understanding mechanisms behind spatial and temporal variability and trends in the flow of the Selenga River and its tributaries, based on hydrological and meteorological station data (since the 1930s), remote sensing, and statistical analyses. Results show that the flow of the Selenga River exhibits cycles with phases of high flows lasting 12 to 17 years and phases of low flows that historically lasted for about 7 years. However, despite an asynchronous behavior between right-bank tributaries and left-bank tributaries, the flow of the Selenga River near its delta at Lake Baikal has now been low (30% below the 1934-1975 average) for as long as 20 years, due to reduced input from precipitation, particularly during the summer season. Observed decreases in annual maximum hourly flows and decreases in annual minimum 30-day flows are consistent with increasing activation of the groundwater system due to thawing permafrost, and higher winter temperatures that support increased winter flows by preventing rivers to freeze from top to bottom. These recent and relatively large changes have implications for regional water planning and management, including the planned large-scale hydropower expansion in the upper part of the Selenga River Basin.
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