75 research outputs found
Experimental Study into the Processes Running in Hydraulic Packer upon Pipeless Water Lifting from Wells by Means of Electrical Submersible Pump
Surface spin magnetism controls the polarized exciton emission from CdSe nanoplatelets
The surface of nominally diamagnetic colloidal CdSe nanoplatelets can
demonstrate paramagnetism owing to the uncompensated spins of dangling bonds
(DBSs). We reveal that by optical spectroscopy in high magnetic fields up to 15
Tesla using the exciton spin as probe of the surface magnetism. The strongly
nonlinear magnetic field dependence of the circular polarization of the exciton
emission is determined by the DBS and exciton spin polarization as well as by
the spin-dependent recombination of dark excitons. The sign of the exciton-DBS
exchange interaction can be adjusted by the nanoplatelet growth conditions
An Assessment of Policy Measures to Support Russia's Real Economy
"This paper presents the results of an analytical project on the design and approbation of methodology for assessing and monitoring the measures taken by the government of the Russian Federation in response to the recent worldwide fiscal crisis. The paper is based on our analysis of about 100 measures initiated between October 2008 and March 2009 to support Russia's real economy. Within the scope of this analysis, we singled out the main beneficiaries according to industry and enterprise scale, and estimated the effects of the measures during the crisis and recovery phases. The paper also describes the major risks the Russian government will face as a result of implementing the aforementioned measures
and identifies the key problems and inconsistencies of the anti-crisis programme." (author's abstract
Electron and hole g-factors and spin dynamics of negatively charged excitons in CdSe/CdS colloidal nanoplatelets with thick shells
We address spin properties and spin dynamics of carriers and charged excitons
in CdSe/CdS colloidal nanoplatelets with thick shells. Magneto-optical studies
are performed by time-resolved and polarization-resolved photoluminescence,
spin-flip Raman scattering and picosecond pump-probe Faraday rotation in
magnetic fields up to 30 T. We show that at low temperatures the nanoplatelets
are negatively charged so that their photoluminescence is dominated by
radiative recombination of negatively charged excitons (trions). Electron
g-factor of 1.68 is measured and heavy-hole g-factor varying with increasing
magnetic field from -0.4 to -0.7 is evaluated. Hole g-factors for
two-dimensional structures are calculated for various hole confining potentials
for cubic- and wurtzite lattice in CdSe core. These calculations are extended
for various quantum dots and nanoplatelets based on II-VI semiconductors. We
developed a magneto-optical technique for the quantitative evaluation of the
nanoplatelets orientation in ensemble
Addressing the exciton fine structure in colloidal nanocrystals: the case of CdSe nanoplatelets
We study the band-edge exciton fine structure and in particular its
bright-dark splitting in colloidal semiconductor nanocrystals by four different
optical methods based on fluorescence line narrowing and time-resolved
measurements at various temperatures down to 2 K. We demonstrate that all these
methods provide consistent splitting values and discuss their advances and
limitations. Colloidal CdSe nanoplatelets with thicknesses of 3, 4 and 5
monolayers are chosen for experimental demonstrations. The bright-dark
splitting of excitons varies from 3.2 to 6.0 meV and is inversely proportional
to the nanoplatelet thickness. Good agreement between experimental and
theoretically calculated size dependence of the bright-dark exciton slitting is
achieved. The recombination rates of the bright and dark excitons and the
bright to dark relaxation rate are measured by time-resolved techniques
Lepidoptera of South Ossetia (Northern Transcaucasia). Part II. Cossidae, Limacodidae, Erebidae (Lymantriinae, Arctiinae, Syntominae, Notodontinae), Lasiocampidae, Lemoniidae, Saturniidae, Sphingidae, Drepanidae and Cimeliidae
In the third part of the publication, we present the faunal list of nine families of the Macrolepidoptera of South Ossetia, including 4 species of Cossidae, 2 species of Limacodidae, 40 species of Erebidae, 15 species of Sphingidae, 6 species of Lasiocampidae, 1 species of Saturniidae and Lemoniidae, 5 species of Drepanidae and 1 species of Cimeliidae. Fifty nine species are reported for South Ossetia for the first time
Stimulation of processes of self-propagating high temperature synthesis in system Ti+Al at low temperatures by influence of [gamma]-quanta
In the present work, the influence of the irradiation with gamma-quanta 60Со upon the structural and phase state of the components of the mechanically activated powder composition of Ti+Al is investigated. The phase composition, structural parameters, and crystallinity are examined by means of X-ray diffractometry. It is found out that the irradiation with gamma-quanta changes the structure of the mechanically activated powder composition. The higher irradiation dose, the higher the structure crystallinity of both components with no change in phase state. At the same time, the parameters of Ti and Al crystal lattices approach to the initial parameters observed before the mechanical activation. The irradiation with gammaquanta leads to decrease of internal stresses in the mechanically activated powder composition while nanocrystallinity of the structure remains unchanged. Using of powder compositions exposed to the irradiation with gamma-quanta for the SH-synthesis helps to increase speed of the reaction, decrease the peak firing temperature and improve homogeneity, as well as the main phase of the produced material is TiAl
Chronicles of nature calendar, a long-term and large-scale multitaxon database on phenology
We present an extensive, large-scale, long-term and multitaxon database on phenological and climatic variation, involving 506,186 observation dates acquired in 471 localities in Russian Federation, Ukraine, Uzbekistan, Belarus and Kyrgyzstan. The data cover the period 1890-2018, with 96% of the data being from 1960 onwards. The database is rich in plants, birds and climatic events, but also includes insects, amphibians, reptiles and fungi. The database includes multiple events per species, such as the onset days of leaf unfolding and leaf fall for plants, and the days for first spring and last autumn occurrences for birds. The data were acquired using standardized methods by permanent staff of national parks and nature reserves (87% of the data) and members of a phenological observation network (13% of the data). The database is valuable for exploring how species respond in their phenology to climate change. Large-scale analyses of spatial variation in phenological response can help to better predict the consequences of species and community responses to climate change.Peer reviewe
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