2,930 research outputs found
Pharmacological efficacy of an inhibitor of arginase-2 KUD975 with L-NAME-induced endothelial dysfunction
The study of endotelio- and cardioprotective activity of finished dosage forms - tablets, film-coated, containing 10 mg of phenolic nature KUD-975, was shown a statistically significant decrease in blood pressure and the coefficient of endothelial dysfunction on the background of simulation L-NAME-induced pathology. In the group of animals treated with KUD975 found a statistically significant increase in the concentrations of stable metabolites of nitric oxide, which in addition to the normalization of vasodilation says about endothelioprotektive action of the compounds studie
The variation of the magnetic field of the Ap star HD~50169 over its 29 year rotation period
Context. The Ap stars that rotate extremely slowly, with periods of decades
to centuries, represent one of the keys to the understanding of the processes
leading to the differentiation of stellar rotation.
Aims. We characterise the variations of the magnetic field of the Ap star HD
50169 and derive constraints about its structure.
Methods. We combine published measurements of the mean longitudinal field
of HD 50169 with new determinations of this field moment from circular
spectropolarimetry obtained at the 6-m telescope BTA of the Special
Astrophysical Observatory of the Russian Academy of Sciences. For the mean
magnetic field modulus , literature data are complemented by the analysis of
ESO spectra, both newly acquired and from the archive. Radial velocities are
also obtained from these spectra.
Results. We present the first determination of the rotation period of HD
50169, Prot = (29.04+/-0.82) y. HD 50169 is currently the longest-period Ap
star for which magnetic field measurements have been obtained over more than a
full cycle. The variation curves of both and have a significant degree
of anharmonicity, and there is a definite phase shift between their respective
extrema. We confirm that HD 50169 is a wide spectroscopic binary, refine its
orbital elements, and suggest that the secondary is probably a dwarf star of
spectral type M.
Conclusions. The shapes and mutual phase shifts of the derived magnetic
variation curves unquestionably indicate that the magnetic field of HD 50169 is
not symmetric about an axis passing through its centre. Overall, HD 50169
appears similar to the bulk of the long-period Ap stars.Comment: 10 pages, 3 figures, accepted for publication in A&
HD 178892 - a cool Ap star with extremely strong magnetic field
We report a discovery of the Zeeman resolved spectral lines, corresponding to
the extremely large magnetic field modulus =17.5 kG, in the cool Ap star HD
178892. The mean longitudinal field of this star reaches 7.5 kG, and its
rotational modulation implies the strength of the dipolar magnetic component
Bp>=23 kG. We have revised rotation period of the star using the All Sky
Automated Survey photometry and determined P=8.2478 d. Rotation phases of the
magnetic and photometric maxima of the star coincide with each other. We
obtained Geneva photometric observation of HD 178892 and estimated
Teff=7700+/-250 K using photometry and the hydrogen Balmer lines. Preliminary
abundance analysis reveals abundance pattern typical of rapidly oscillating Ap
stars.Comment: Accepted by Astronomy & Astrophysics; 4 pages, 4 figure
Influence of Al on the structure and in vitro behavior of hydroxyapatite nanopowders
Nanopowders of aluminum-substituted (0-20 mol %) hydroxyapatite (HA) with the average size of 40-60 nm were synthesized by the precipitation method from nitrate solutions. A series of samples were studied by various analytical tools to elucidate the peculiarities of al introductio
Influence of ripening in mother solution on characteristics of magnesium-substituted calcium phosphate powders
Effect of ripening in the mother liquor on the degree of crystallinity and dispersity of mixed powders of calcium and magnesium phosphates is studied as a function of magnesium content with the elemental composition such that (Ca + Mg)/P = 2. Ripening is found to have a positive effect on crystallinity of the apatite phase of powders. Nanocrystals with lowered tendency to aggregation are formed during the ripening period, which affords the powders with specific surface area as high as 80 m2/g. The morphology of the constituent particles depends on the magnesium content. Crystallization processes are essentially completed by the 21st day of ripenin
Raman fingerprints of ultrasmall nanodiamonds produced from adamantane
The synthesis of ultrasmall (2-5 nm) nanodiamonds purely from adamantane at
pressure of 12 GPa is reported. Their structural features have been studied by
Raman spectroscopy. The unusual vibration band containing a number of
pronounced maxima at about 1147, 1245, 1344, and 1456 cm-1 was detected in
Raman spectra. The band is confidently identified with the bending vibrational
modes of CHx groups terminating the nanodiamonds surface. Excessively intense
mode at 1344 cm-1 is explained by its coupling with the 1328 cm-1 diamond
phonons. The Raman band found is proposed to be used for express recognition of
ultrasmall nanodiamonds produced from adamantane and other hydrocarbons with a
high hydrogen content. Moreover, polarized CH bonds on a diamond surface are
sensitive to environmental conditions. This opens up opportunities for using
the diamond produced from adamantane as ultrasmall nanosensors in biology,
chemistry, and medicineComment: 12 pages, 6 figure
HD 965: An extremely peculiar A star with an extremely long rotation period
Context. One of the keys to understanding the origin of the Ap stars and
their significance in the general context of stellar astrophysics is the
consideration of the most extreme properties displayed by some of them. In that
context, HD 965 is particularly interesting, as it combines some of the most
pronounced chemical peculiarities with one of the longest rotation periods
known.
Aims. We characterise the variations of the magnetic field of the Ap star HD
965 and derive constraints about its structure.
Methods. We combine published measurements of the mean longitudinal field
of HD 965 with new determinations of this field moment from circular
spectropolarimetry obtained at the 6-m telescope BTA of the Special
Astrophysical Observatory of the Russian Academy of Sciences. For the mean
magnetic field modulus , literature data are complemented by the analysis of
ESO archive spectra.
Results. We present the first determination of the rotation period of HD 965,
P = (16.5+/-0.5) y. HD 965 is only the third Ap star with a period longer than
10 years for which magnetic field measurements have been obtained over more
than a full cycle. The variation curve of is well approximated by a cosine
wave. does not show any significant variation. The observed behaviour of
these field moments is well represented by a simple model consisting of the
superposition of collinear dipole, quadrupole and octupole. The distribution of
neodymium over the surface of HD 965 is highly non-uniform. The element appears
concentrated around the magnetic poles, especially the negative one.
Conclusions. The shape of the longitudinal magnetic variation curve of HD 965
indicates that its magnetic field is essentially symmetric about an axis
passing through the centre of the star. Overall, as far as its magnetic field
is concerned, HD 965 appears similar to the bulk of the long-period Ap stars.Comment: 7 pages, 4 figures, accepted for publication in Astronomy &
Astrophysics. arXiv admin note: text overlap with arXiv:1902.0586
Aspects of a0-f0 mixing in the reaction pn->da0
Some aspects of a0-f0 mixing effects in the reaction
with perpendicular polarized proton beam are discussed. An angular--asymmetry
parameter is defined to study those effects. It is shown that, for energies
close to the production threshold, the angular--asymmetry parameter is proportional to the a0-f0 mixing amplitude for arbitrary polar and
azimuthal angles and of the outgoing meson. This
statement is also valid for arbitrary energies, but then only at polar angles
and . The mass dependence of the differential cross
section in the reaction in the
presence of \mix mixing is also discussed.Comment: 17 pages, 3 Figure
Spectral and localization properties of the Dirichlet wave guide with two concentric Neumann discs
Bound states of the Hamiltonian describing a quantum particle living on three
dimensional straight strip of width are investigated. We impose the Neumann
boundary condition on the two concentric windows of the radii and
located on the opposite walls and the Dirichlet boundary condition on the
remaining part of the boundary of the strip. We prove that such a system
exhibits discrete eigenvalues below the essential spectrum for any .
When and tend to the infinity, the asymptotic of the eigenvalue is
derived. A comparative analysis with the one-window case reveals that due to
the additional possibility of the regulating energy spectrum the anticrossing
structure builds up as a function of the inner radius with its sharpness
increasing for the larger outer radius. Mathematical and physical
interpretation of the obtained results is presented; namely, it is derived that
the anticrossings are accompanied by the drastic changes of the wave function
localization. Parallels are drawn to the other structures exhibiting similar
phenomena; in particular, it is proved that, contrary to the two-dimensional
geometry, at the critical Neumann radii true bound states exist.Comment: 25 pages, 7 figure
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