Search results for "Application"
showing 10 items of 5559 documents
Indoor Fast Neutron Generator for Biophysical and Electronic Applications
2018
This study focuses the attention on an indoor fast neutron generator for biophysical and electronic applications. More specifically, the findings obtained by several simulations with the MCNP Monte Carlo code, necessary for the realization of a shield for indoor measurements, are presented. Furthermore, an evaluation of the neutron spectrum modification caused by the shielding is reported. Fast neutron generators are a valid and interesting available source of neutrons, increasingly employed in a wide range of research fields, such as science and engineering. The employed portable pulsed neutron source is a MP320 Thermo Scientific neutron generator, able to generate 2.5 MeV neutrons with a …
Theoretical investigations of nitrogen doping on Co 3 O 4 for water dissociation catalytically activity
2018
We report the results of theoretical investigations of nitrogen doping on Co 3 O 4 (100) bulk by means of the plane-wave periodic density functional theory (DFT) calculations combined with the Hubbard-U approach and statistical thermodynamics.Using accurate DFT+U calculations, we have shown that bulk Co ions denote charges in value 0.017 - 0.57e. For further water adsorption process studies was selected structures with most changes in charges in Co ions: (3) structure for n = 25%, (2) structure forn = 12.5% and structure for (1) structure.
Optical-sectioning microscopy by patterned illumination
2010
We propose a very simple method for the flexible production of 1D structured illumination for high resolution 3D microscopy. Specifically, we propose the insertion of a Fresnel biprism after a monochromatic point source for producing a pair of twin, fully coherent, virtual point sources. The resulting interference fringes are projected into the 3D sample and, by simply varying the distance between the biprism and the point source, one can tune the period of the fringes, while keeping their contrast, in a very versatile and efficient way.
Acoustic properties of nanoscale oxide heterostructures probed by UV Raman spectroscopy
2007
We study high quality molecular-beam epitaxy grown BaTiO3/SrTiO3 superlat-tices using ultraviolet Raman spectroscopy. In the low energy spectral region, acoustic phonon doublets are observed. These are due to the artificial superlattice periodicity and consequent folding of the acoustic phonon dispersion. From the study of samples with different BaTiO3/SrTiO3 layer thicknesses the effective sound velocities within each of the layers are obtained.
Presentation of the DSIP method for study of recrystallization process in subsurface zone induced by sandblasting
2011
In the paper we demonstrate the application of the positron annihilation experimental technique based on the scan of the positron implantation profile for observation of the recrystallization process in the subsurface zone (SZ). The SZ was created in the copper sample whose surface was exposed to a sandblasting treatment and then annealed at different temperatures. Application of 68Ge/68Ga positron source allows us to scan the depth of c.a. 150 μm. It was found that recrystallization goes faster close to the surface than in deeper regions. The complete rebuilding of the microstructure takes place at temperature of 600 °C. Some changes in the defect structure begin at temperature of 300 °C.
Transition levels of acceptor impurities in ZnO crystals by DFT-LCAO calculations
2018
This research was partly supported by the Kazakhstan Science Project № AP05134367«Synthesis of nanocrystals in track templates of SiO2/Si for sensory, nano-and optoelectronic applications» and Latvian Super Cluster (LASC), installed in the Institute of Solid State Physics (ISSP) of the University of Latvia. Authors are indebted to D. Gryaznov, A. Popov and A. Dauletbekova for stimulating discussions.
Devitrification of the Kob-Andersen glass former: Competition with the locally favored structure
2018
Abstract Supercooled liquids are kinetically trapped materials in which the transition to a thermodynamically more stable state with long-range order is strongly suppressed. To assess the glass-forming abilities of a liquid empirical rules exist, but a comprehensive microscopic picture of devitrification is still missing. Here we study the crystallization of a popular model glass former, the binary Kob-Andersen mixture, in small systems. We perform trajectory sampling employing the population of the locally favored structure as order parameter. While for large population a dynamical phase transition has been reported, here we show that biasing towards a small population of locally favored s…
On damping characteristics of frictional hysteresis in pre-sliding range
2016
Frictional hysteresis at relative motion in the pre-sliding range is considered. This effect is characterized by an elasto-plastic interaction, and that on the micro-scale, between two rubbing surfaces in contact that gives rise to nonlinear friction force. The pre-sliding friction force yields hysteresis in displacement. In this study, the damping characteristics of frictional hysteresis are analyzed. It is worth noting that we exclude the viscous damping mechanisms and focus on the pure hysteresis damping to be accounted in the friction modeling. The general properties of pre-sliding friction hysteresis are demonstrated and then compared with the limit case of discontinuous Coulomb fricti…
The luminescence properties of ZnO nanopowders
2007
Pure and Al3+ doped ZnO nanopowders were studied by means of time-resolved luminescence spectroscopy. The powders were synthesized by hydrothermal and plasma methods. These powders were used as a raw material for vaporization-condensation process inside the Solar reactor. The commercially available ZnO nanopowder was studied for a comparison. Exciton to defect band luminescence intensity ratio was estimated in different types of ZnO nanopowders. It was found that nanopowders with whiskers morphology show superlinear luminescence intensity depending on excitation density. The observed effect depends on the average nanoparticle size and on the powder morphology.
Comparison of effects on crustaceans: carbon nanoparticles and molybdenum compounds nanowires
2013
Carbon nanomaterials (CNM) and molybdenum compound nanostructures are materials with various applications yet little is known regarding the toxicity of these nanoparticles in pristine form in aquatic environment. Daphnia magna standard acute toxicity test (EN ISO 6341:1996; freshwater) and Artemia salina standard acute toxicity test (ArtoxKit standard method; 15 ppt saltwater) were applied to assess the toxicity of non-modified CNM and molybdenum compound nanowires in water. It has been observed that CNM are more toxic in freshwater suspensions and somewhat more toxic than the tested molybdenum compound nanowires.