195 research outputs found
Spatial regularity of the young stellar population in the ring of NGC 6217
The relative contribution of various physical processes to the spatial and
temporal distribution of molecular clouds and star-forming regions in the disks
of galaxies has not been fully studied. The spatial regularity in the
distribution of the young stellar population in spiral and ring structures is a
good test to study this contribution. We investigate photometric properties of
the ring and spiral arms in the barred spiral galaxy NGC 6217 based on analysis
of GALEX ultraviolet, optical UBVRI and Halpha surface photometry data. The
ring in the galaxy is located near the corotation area. A spatial regularity in
the distribution of the young stellar population along the galaxy ring was
found. The characteristic scale of spacing is about 700 pc. At the same time,
we did not find a similar regularity in the distribution of the young stellar
population along the spiral arms of NGC 6217. The spatial regularity in
concentration of young stellar groupings along spiral arms is a quite rare
phenomenon, and it has never been found before in galactic rings.Comment: 5 pages, 5 figures, 2 tables. Accepted for publication in A&A Letters
(v2 is the final version
Foam Metals High-Temperature Electrical Characteristics’ Investigation
In the work presented we have carried out experimental investigations of high- temperature electrophysical
properties of foam metals. We have obtained data of foam nickel and foam copper resistivity
and temperature coefficients of resistance (TCR) versus their plane deformation degree within the
temperature range from 100 to 950 ºС
Medium-Dependent Antibacterial Properties and Bacterial Filtration Ability of Reduced Graphene Oxide
Toxicity of reduced graphene oxide (rGO) has been a topic of multiple studies and was shown to depend on a variety of characteristics of rGO and biological objects of interest. In this paper, we demonstrate that when studying the same dispersions of rGO and fluorescent Escherichia coli (E. coli) bacteria, the outcome of nanotoxicity experiments also depends on the type of culture medium. We show that rGO inhibits the growth of bacteria in a nutrition medium but shows little effect on the behavior of E. coli in a physiological saline solution. The observed effects of rGO on E. coli in different media could be at least partially rationalized through the adsorption of bacteria and nutrients on the dispersed rGO sheets, which is likely mediated via hydrogen bonding. We also found that the interaction between rGO and E. coli is medium-dependent, and in physiological saline solutions they form stable flocculate structures that were not observed in nutrition media. Furthermore, the aggregation of rGO and E. coli in saline media was observed regardless of whether the bacteria were alive or dead. Filtration of the aggregate suspensions led to nearly complete removal of bacteria from filtered liquids, which highlights the potential of rGO for the filtration and separation of biological contaminants, regardless of whether they include live or dead microorganisms
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